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Sample records for induced luminescence characterisation

  1. Spectrometer for cluster ion beam induced luminescence

    SciTech Connect

    Ryuto, H. Sakata, A.; Takeuchi, M.; Takaoka, G. H.; Musumeci, F.

    2015-02-15

    A spectrometer to detect the ultra-weak luminescence originated by the collision of cluster ions on the surfaces of solid materials was constructed. This spectrometer consists of 11 photomultipliers with band-pass interference filters that can detect the luminescence within the wavelength ranging from 300 to 700 nm and of a photomultiplier without filter. The calibration of the detection system was performed using the photons emitted from a strontium aluminate fluorescent tape and from a high temperature tungsten filament. Preliminary measurements show the ability of this spectrometer to detect the cluster ion beam induced luminescence.

  2. Mechanically induced residual stresses: Modelling and characterisation

    NASA Astrophysics Data System (ADS)

    Stranart, Jean-Claude E.

    Accurate characterisation of residual stress represents a major challenge to the engineering community. This is because it is difficult to validate the measurement and the accuracy is doubtful. It is with this in mind that the current research program concerning the characterisation of mechanically induced residual stresses was undertaken. Specifically, the cold expansion of fastener holes and the shot peening treatment of aerospace alloys, aluminium 7075 and titanium Ti-6Al-4V, are considered. The objective of this study is to characterise residual stresses resulting from cold working using three powerful techniques. These are: (i) theoretical using three dimensional non-linear finite element modelling, (ii) semi-destructive using a modified incremental hole drilling technique and (iii) nondestructive using a newly developed guided wave method supplemented by traditional C-scan measurements. The three dimensional finite element results of both simultaneous and sequential cold expansion of two fastener holes revealed the importance of the separation distance, the expansion level and the loading history upon the development and growth of the plastic zone and unloading residual stresses. It further showed that the commonly adopted two dimensional finite element models are inaccurate and incapable of predicting these residual stresses. Similarly, the dynamic elasto-plastic finite element studies of shot peening showed that the depth of the compressed layer, surface and sub-surface residual stresses are significantly influenced by the shot characteristics. Furthermore, the results reveal that the separation distance between two simultaneously impacting shots governs the plastic zone development and its growth. In the semi-destructive incremental hole drilling technique, the accuracy of the newly developed calibration coefficients and measurement techniques were verified with a known stress field and the method was used to measure peening residual stresses. Unlike

  3. Photoacoustic effect induced by negative luminescence device

    NASA Astrophysics Data System (ADS)

    Kuusela, T.; Peura, J.; Matveev, B. A.; Remennyy, M. A.; Stus', N. M.

    2010-07-01

    The cantilever enhanced photoacoustic trace gas detection technique has been combined with mid-infrared light emitting diodes (LEDs) producing significant negative luminescence at a reverse bias. In contrast to normal positive photoacoustic phenomenon the negative luminescence of the LED creates wavelength specific cooling of the gas under study and pressure drop in the photoacoustic sample cell, which can be detected by a cantilever microphone. In experiments a LED operating at 5.5 μm wavelength range was used to detect acetone vapor.

  4. Dehydration-induced luminescence in clay minerals

    NASA Technical Reports Server (NTRS)

    Coyne, L. M.; Lahav, N.; Lawless, J. G.

    1981-01-01

    Reports of triboluminescent phenomena in organic crystalline materials prompted a search for related processes in clay minerals. The reported extensive mechanical distortion produced on freezing and drying of montmorillonite was particularly interesting because of studies of condensation reactions in a wet/dry cycled reaction sequence. The discovery of an unusual luminescent process in several clay minerals is reported and its characteristics are described.

  5. Ion beam induced luminescence analysis of painting pigments

    NASA Astrophysics Data System (ADS)

    Quaranta, A.; Salomon, J.; Dran, J. C.; Tonezzer, M.; Della Mea, G.

    2007-01-01

    Ion beam induced luminescence (IBIL) has been exploited for the first time in the analysis of inorganic painting pigments. The elemental constituents of the different compounds have been determined by particle induced X-ray emission (PIXE). The acquisition time of each spectrum ranges from 100 ms to a few seconds, depending on the luminescence intensity. The luminescence features are fingerprints of the different compounds, thus identifying the provenience of pigments of the same nominal composition. Organic varnish layers do not affect the IBIL features, allowing the identification of pigments, like lapis-lazuli, whose identification with PIXE is hindered by the varnish. IBIL proved to be a technique complementary to PIXE in the archeometry and cultural heritage analysis fields.

  6. Ion beam induced luminescence: Relevance to radiation induced bystander effects

    NASA Astrophysics Data System (ADS)

    Ahmad, S. B.; McNeill, F. E.; Byun, S. H.; Prestwich, W. V.; Seymour, C.; Mothersill, C. E.

    2012-10-01

    The aim of this work is quantify the light emitted as a result of charged particle interaction in materials which may be of relevance to radiation induced "bystander effects" studies. We have developed a system which employs single photon counting to measure the light emitted from samples irradiated under vacuum by a charged particle beam. The system uses a fast photomultiplier tube with a peak cathode response at 420 nm. It has been tested in a proof-of-principle experiment using polystyrene targets. Light output, as a result of irradiation, was measured. The luminescence yield appears to have a non-linear behavior with the incident ion fluence: it rises exponentially to an asymptotic value. The target was irradiated with beam energies varying from 1 to 2 MeV and showed saturation at or before an incident fluence rate of 3 × 1013 H+/cm2 s. The average saturation value for the photon output was found to be 40 × 106 cps. Some measurements were performed using filters to study the emission at specific wavelengths. In the case of filtered light measurements, the photon output was found to saturate at 28 × 103, 10 × 106, and 35 × 106 cps for wavelengths of 280 ± 5 nm, 320 ± 5 nm and 340 ± 5 nm respectively. The light output reaches a maximum value because of damage induced in the polymer. Our measurements indicate a "damage cross section" of the order of 10-14 cm2. The average radiant intensity was found to increase at wavelengths of 280 and 320 nm when the proton energy was increased. This was not found to occur at 340 nm. In conclusion, the light emission at specific wavelengths was found to depend upon the incident proton fluence and the proton energy. The wavelengths of the emitted light measured in this study have significance for the understanding of radiation induced bystander effects.

  7. Characterization of dehydration-induced luminescence of kaolinite

    NASA Technical Reports Server (NTRS)

    Lahav, N.; Coyne, L.; Lawless, J. G.

    1985-01-01

    The dehydration-induced luminescence of a colloidal kaolinite is investigated experimentally, with particular attention given to the effect of various treatments on the luminescence characteristics. It is found that the total photon count of the emitted light is linearly related to the film thickness up to a thickness of 30 microns; mechanical stress in the form of grinding increases the photon output and produces extensive changes in the emission kinetics. A direct check of the emission wavelength dependence (by using color filters) indicates that roughly 75 percent of the emission occurs in the wavelength range below 410 nm. It is also found that incorporation of fluorescent molecules into the kaolinite paste increases the photon output and may indicate the transfer of ultraviolet photons to the fluorescent probe.

  8. Characterisation, degradation and regeneration of luminescent Ag29 clusters in solution.

    PubMed

    van der Linden, Marte; Barendregt, Arjan; van Bunningen, Arnoldus J; Chin, Patrick T K; Thies-Weesie, Dominique; de Groot, Frank M F; Meijerink, Andries

    2016-12-01

    Luminescent Ag clusters are prepared with lipoic acid (LA) as the ligand. Using a combination of mass spectrometry, optical spectroscopy and analytical ultracentrifugation, the clusters are found to be highly monodisperse with mass 5.6 kDa. We assign the chemical composition [Ag29(LA)12](3-) to the clusters, where LA likely binds in a bidentate fashion. The Ag29 clusters show slow degradation, retaining their deep red emission for at least 18 months if stored in the dark. Purification or exposure to light results in faster degradation. No other cluster species are observed during the degradation process. Once degraded, the clusters could easily be regenerated using NaBH4, which is not usually observed for thiolate-capped Ag clusters.

  9. Synthesis, characterisation, optical and luminescence properties of CoAl{sub 2}O{sub 4}

    SciTech Connect

    Agilandeswari, K.; Kumar, A. Ruban

    2015-06-24

    Solid state method has been used as an efficient method to synthesize blue pigment CoAl{sub 2}O{sub 4} at a temperature of 800°C. The products were characterized by powder X-ray diffraction (XRD), Fourier transformer infrared spectroscopy (FTIR), UV-Visible diffuse reflectance spectroscopy (DRS) and luminescent spectroscopy. X-ray diffraction pattern confirmed the formation of single phase CoAl{sub 2}O{sub 4}. Optical properties of CoAl{sub 2}O{sub 4} ceramic shows an energy band gap in the range of 3.10eV. The emission spectra of spinel CoAl{sub 2}O{sub 4} in the visible region confirmed the presence of tetrahedral coordinated Co{sup 2+} ions.

  10. Spectrographic studies: Electron induced luminescence in optical materials

    NASA Technical Reports Server (NTRS)

    Romanko, J.; Miles, J. K.; Cheever, P. R.

    1971-01-01

    The spectral luminescence induced in UV grade sapphire, MgF2 and LiF2, three fused silicas, and three Corning glasses, by 1/2, 1, 2, and 3 MeV electrons was recorded. In the wavelength range from the LiF UV cutoff to the near visible, a plane-grating spectrograph with photographic recording at resolutions of 0.8 and 1.6 nm was utilized. Qualitative results based on relative density tracings of seven of the nine materials obtained from preliminary plates are given.

  11. Space-radiation-induced Photon Luminescence of the Moon

    NASA Technical Reports Server (NTRS)

    Wilson, Thomas; Lee, Kerry

    2008-01-01

    We report on the results of a study of the photon luminescence of the Moon induced by Galactic Cosmic Rays (GCRs) and space radiation from the Sun, using the Monte Carlo program FLUKA. The model of the lunar surface is taken to be the chemical composition of soils found at various landing sites during the Apollo and Luna programs, averaged over all such sites to define a generic regolith for the present analysis. This then becomes the target that is bombarded by Galactic Cosmic Rays (GCRs) and Solar Energetic Particles (SEPs) above 1 keV in FLUKA to determine the photon fluence albedo produced by the Moon's surface when there is no sunlight and Earthshine. This is to be distinguished from the gamma-ray spectrum produced by the radioactive decay of radiogenic constituents lying in the surface and interior of the Moon. From the photon fluence we derive the spectrum which can be utilized to examine existing lunar spectral data and to design orbiting instrumentation for measuring various components of the space-radiation-induced photon luminescence present on the Moon.

  12. A thermo-responsive supramolecular organogel: dual luminescence properties and luminescence conversion induced by Cd(2+).

    PubMed

    Ma, Xinxian; Zhang, Jinjin; Tang, Ning; Wu, Jincai

    2014-12-14

    A simple dual luminescent acylhydrazone-functionalized benzimidazole derivative (L) was blended with ethylene glycol affording a thermo-responsive green-light-emitting supramolecular gel (G-gel). This G-gel can convert to a blue-light-emitting gel (B-gel) by strongly increasing the luminescence of the benzimidazole moiety upon addition of one equivalent of Cd(2+).

  13. GCR-Induced Photon Luminescence of the Moon

    NASA Technical Reports Server (NTRS)

    Lee, K. T.; Wilson, T. L.

    2008-01-01

    It is shown that the Moon has a ubiquitous photon luminescence induced by Galactic cosmic-rays (GCRs), using the Monte Carlo particle-physics program FLUKA. Both the fluence and the flux of the radiation can be determined by this method, but only the fluence will be presented here. This is in addition to thermal radiation emitted due to the Moon s internal temperature and radioactivity. This study is a follow-up to an earlier discussion [1] that addressed several misconceptions regarding Moonshine in the Earth-Moon system (Figure 1) and predicted this effect. There also exists a related x-ray fluorescence induced by solar energetic particles (SEPs, <350 MeV) and solar photons at lower x-ray energies, although this latter fluorescence was studied on Apollo 15 and 16 [2- 5], Lunar Prospector [6], and even EGRET [7].

  14. First measurements of laser-accelerated proton induced luminescence

    SciTech Connect

    Floquet, V.; Ceccotti, T.; Dobosz Dufrenoy, S.; Bonnaud, G.; Monot, P.; Martin, Ph.; Gremillet, L.

    2012-09-15

    We present our first results about laser-accelerated proton induced luminescence in solids. In the first part, we describe the optimization of the proton source as a function of the target thickness as well as the laser pulse duration and energy. Due to the ultra high contrast ratio of our laser beam, we succeeded in using targets ranging from the micron scale down to nanometers thickness. The two optimal thicknesses we put in evidence are in good agreement with numerical simulations. Laser pulse duration shows a small influence on proton maximum energy, whereas the latter turns out to vary almost linearly as a function of laser energy. Thanks to this optimisation work, we have been able to acquire images of the proton energy deposition in a solid scintillator.

  15. In situ variations of carrier decay and proton induced luminescence characteristics in polycrystalline CdS

    SciTech Connect

    Gaubas, E. Ceponis, T.; Jasiunas, A.; Kalesinskas, V.; Meskauskaite, D.; Pavlov, J.; Tamulaitis, G.; Tekorius, A.; Brytavskyi, I.; Kovalevskij, V.; Remeikis, V.

    2014-06-28

    Evolution of the microwave-probed photoconductivity transients and of the proton induced luminescence has simultaneously been examined in polycrystalline CdS layers evaporated in vacuum during exposure to a 1.6 MeV proton beam. The decrease of the intensity of luminescence peaked at 510 and 709 nm wavelengths and of values of the effective carrier lifetime has been correlated in dependence of proton irradiation fluence. The defect introduction rate has been evaluated by the comparative analysis of the laser and proton beam induced luminescence. The difference of a carrier pair generation mechanism inherent for light and for a proton beam has been revealed.

  16. Room-temperature luminescence from kaolin induced by organic amines

    NASA Technical Reports Server (NTRS)

    Coyne, L. M.; Kloepping, R.; Pollack, G.

    1984-01-01

    Several new, room-temperature luminescent phenomena, resulting from the interaction of kaolin and various amino compounds, have been observed. The emission of light from kaolin pastes (treated with quinoline, pyridine, hydrazine, monoethanolamine, n-butylamine, and piperidine) was shown to decay monotonically over a period of hours to days. More light was released by a given amino compound after it was dried and purified. Hydrazine, in addition to the monotonically decaying photon release, produces delayed pulses of light with peak emission wavelength of 365 nm which last between several hours and several days. These photon bursts are acutely sensitive to the initial dryness of the hydrazine, both in the number of bursts and the integrated photon output. The amount of light and the capacity of the kaolin to produce the delayed burst appeared to be strongly dependent on preliminary heating and on gamma-irradiation, analogous to the dehydration-induced light pulse previously reported from the Ames Research Center. A small, delayed burst of photons occurred when piperidine and n-butylamine were removed by evaporation into an H2SO4 reservoir.

  17. Characterisation of estuarine intertidal macroalgae by laser-induced fluorescence

    NASA Astrophysics Data System (ADS)

    Gameiro, Carla; Utkin, Andrei B.; Cartaxana, Paulo

    2015-12-01

    The article reports the application of laser-induced fluorescence (LIF) for the assessment of macroalgae communities of estuarine intertidal areas. The method was applied for the characterisation of fifteen intertidal macroalgae species of the Tagus estuary, Portugal, and adjacent coastal area. Three bands characterised the LIF spectra of red macroalgae with emission maxima in the ranges 577-583 nm, 621-642 nm and 705-731 nm. Green and brown macroalgae showed one emission maximum in the red region (687-690 nm) and/or one in the far-red region (726-732 nm). Characteristics of LIF emission spectra were determined by differences in the main fluorescing pigments: phycoerythrin, phycocyanin and chlorophyll a (Chl a). In the green and brown macroalgae groups, the relative significance of the two emission maxima seems to be related to the thickness of the photosynthetic layer. In thick macroalgae, like Codium tomentosum or Fucus vesiculosus, the contribution of the far-red emission fluorescence peak was more significant, most probably due to re-absorption of the emitted red Chl a fluorescence within the dense photosynthetic layer. Similarly, an increase in the number of layers of the thin-blade green macroalgae Ulva rigida caused a shift to longer wavelengths of the red emission maximum and the development of a fluorescence peak at the far-red region. Water loss from Ulva's algal tissue also led to a decrease in the red/far-red Chl fluorescence ratio (F685/F735), indicating an increase in the density of chloroplasts in the shrinking macroalgal tissue during low tide exposure.

  18. Luminescence modulations of rhenium tricarbonyl complexes induced by structural variations.

    PubMed

    Bertrand, Hélène C; Clède, Sylvain; Guillot, Régis; Lambert, François; Policar, Clotilde

    2014-06-16

    Octahedral d(6) low-spin Re(I) tricarbonyl complexes are of considerable interest as noninvasive imaging probes and have been deeply studied owing to their biological stability, low toxicity, large Stokes shifts, and long luminescence lifetimes. We reported recently the bimodal IR and luminescence imaging of a Re(I) tricarbonyl complex with a Pyta ligand (4-(2-pyridyl)-1,2,3-triazole) in cells and labeled such metal-carbonyl complexes SCoMPIs for single-core multimodal probes for imaging. Re(I) tricarbonyl complexes have unique photophysical properties allowing for their unequivocal detection in cells but also present some weaknesses such as a very low luminescence quantum yield in aqueous medium. Further optimizations would thus be desirable. We therefore developed new Re(I) tricarbonyl complexes prepared from different ancillary ligands. Complexes with benzothiadiazole-triazole ligands show interesting luminescent quantum yields in acetonitrile and may constitute valuable luminescent metal complexes in organic media. A series of complexes with bidentate 1-(2-quinolinyl)-1,2,3-triazole (Taquin) and 1-(2-pyridyl)-1,2,3-triazole (Tapy) ligands bearing various 4-substituted alkyl side chains has been designed and synthesized with efficient procedures. Their photophysical properties have been characterized in acetonitrile and in a H2O/DMSO (98/2) mixture and compared with those of the parent Quinta- and Pyta-based complexes. Tapy complexes bearing long alkyl chains show impressive enhancement of their luminescent properties relative to the parent Pyta complex. Theoretical calculations have been performed to further characterize this new class of rhenium tricarbonyl complexes. Preliminary cellular imaging studies in MDA-MB231 breast cancer cells reveal a strong increase in the luminescence signal in cells incubated with the Tapy complex substituted with a C12 alkyl chain. This study points out the interesting potential of the Tapy ligand in coordination chemistry

  19. Characterization of dehydration-induced luminescence of kaolinite.

    PubMed

    Lahav, N; Coyne, L; Lawless, J G

    1985-01-01

    Dehydration-induced luminescence (DIL), the emission of light from a clay paste upon dehydration, was characterized experimentally for a colloidal kaolinite. The relationship between total photon count of the emitted light and film thickness is linear up to a thickness of 30 micrometers. The photon emission was obtained over a critical range of water contents (25-60%) of the oven-dry clay, and the kinetics of photon emission was presumed to be closely associated with the kinetics of film dehydration. Whether drying proceeded throughout the bulk or via a moving front was undetermined, but in either mode it was preceded by the formation of a thin dry film at the interface with the atmosphere. Grinding of the kaolinite for several minutes by mortar and pestle before paste preparations resulted in an overall increase of photon emission compared to unground kaolinite and in the formation of more than one emission peak, as well as a prolongation of the light emission. This effect on the kinetics of light emittance was observed for about two months after the application of the mechanical stress and suggests a means of detecting the mechanical stress history of a clay. An estimate was made of the spectral characteristics of the emitted light using optical filters and by incorporating tryptophan and salicylic acid into the kaolinite paste where they acted as fluorescent probes. The latter technique shifted the frequency of the light emitted by the kaolinite from the ultraviolet to the visible range where it was less effectively reabsorbed. The first method showed that the wavelengths of 97% of the emitted light was <460 nm and that 75% of the light had wavelengths < 410 nm. The second method showed that the total intensity of DIL increased in the presence of fluorescence molecules, suggesting that the emittance was in the ultraviolet range.

  20. The influence of the crystal structure on aggregation-induced luminescence of derivatives of aminobenzoic acid

    NASA Astrophysics Data System (ADS)

    Nosova, D. A.; Zarochentseva, E. P.; Vysotskaya, S. O.; Klemesheva, N. A.; Korotkov, V. I.

    2014-12-01

    The luminescence of three derivatives of 2-(phenylamino)-benzoic acid (N-phenylanthranilic, mefenamic, and niflumic acids) in benzene solution, in the polycrystalline state, and in the hexamethylbenzene matrix is studied. In the crystalline state, these compounds exhibit intense aggregation-induced luminescence. An increase in luminescence is also observed in the impurity crystal. The hexamethylbenzene crystal lattice restricts the mobility of molecules, thus ensuring the rigidity of the molecular structure of acids, which decreases the efficiency of nonradiative electron energy degradation. The main reason for the increase in the luminescence intensity in the case of fixation in a crystalline matrix is the formation of intramolecular hydrogen bonds and dimers of acid molecules.

  1. Characterisation of the luminescence properties of BAM:Eu2+ particles as a tracer for thermographic particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Fond, Benoit; Abram, Christopher; Beyrau, Frank

    2015-12-01

    Thermographic phosphor particles are seeded into the flow as tracers for simultaneous temperature and velocity measurements in fluids. Several studies using different phosphors as gas-phase tracers have been published in recent years. However, little is known about their emission characteristics when they are dispersed as individual particles in the fluid. In this paper, the luminescence properties of BAM:Eu2+ particles, a phosphor with favourable characteristics (short luminescence lifetime, blue emission spectrum, high quantum efficiency), are thoroughly investigated in the gas phase. Using a recently developed particle-counting tool, the emission intensity per particle is measured over a wide range of conditions, including for various temperatures from 300 to 920 K, in air and in pure nitrogen. The luminescence emission per particle is shown to drop with temperature, but to be insensitive to the seeding density and to the oxygen content over the tested range. Together with a spectroscopic study, and a statistical error analysis, these results are used to predict the temperature precision of the technique under various conditions for different filter combinations and to assess the current upper temperature limit of this phosphor for practical applications. Potential additional sources of uncertainty are also investigated, including cross-dependencies of the measured intensity ratio on the seeding density, excitation fluence and oxygen partial pressure in the gas phase. Only a weak dependence on the laser fluence is observed, while the measured intensity ratio is shown to be insensitive to both seeding density and the oxygen volume fraction. Finally, the saturation behaviour of the phosphorescence emission is examined, through theoretical considerations and measurements performed with different excitation schemes in an attempt to increase signal levels. In conclusion, this paper confirms that BAM:Eu2+ is a very suitable tracer for measurements in turbulent flows

  2. Changes in ultraweak luminescence from living fish induced by three chemicals

    SciTech Connect

    Wang Yingyan; Li Da ); Ma Yuqin; Li Shenxun; Zhang Yujing; Song Xueling )

    1991-03-01

    Ultraweak luminescence is a ubiquitous phenomenon in biological systems, which differs from bioluminescence of luciferin-luciferase. This low-intensity emission is inherently associated with the following important process such as oxidative metabolism, cell division, carcinogenesis, photosynthesis, and cell death. In general, ultraweak luminescence may be classified as two kinds, namely spontaneous and induced. Zebra fish is a recommended specimen for toxicity and toxicological test. The purpose of this, the changes before and after the treatment with three chemicals: uranium oxides, sodium azide or cyclophosphamide and their correlations between the dose and effect.

  3. Radiation-induced luminescence in magnesium aluminate spinel crystals and ceramics

    NASA Astrophysics Data System (ADS)

    Gritsyna, V. T.; Kazarinov, Yu. G.; Kobyakov, V. A.; Reimanis, I. E.

    2006-09-01

    Radioluminescence (RL) and thermoluminescence (TL) in spinel crystals and ceramics were investigated to elucidate the radiation-induced electronic processes in single crystals grown by Verneuil and Czochralski methods as well as transparent and translucent ceramics. Both RL and TL spectra demonstrate a UV-band related to electron-hole recombination luminescence at intrinsic defects; green and red luminescence are identified with emission of Mn 2+- and Cr 3+-ions, respectively. The kinetics of growth of different RL luminescence bands depending on dose at the prolonged X-irradiation shows the competitive character of charge and energy transfer between defects and impurity ions. The dependence of RL intensity on the temperature of the sample was measured in the range of 300-750 K and compared with TL for different emission bands. The variety of maxima in the temperature dependence of RL and in the glow curves of TL measured for different luminescence bands in spinels of different origins and crystalline forms is used to show that charge carrier traps and luminescence centers are not isolated defects but are complexes of defects and impurities. The formation, structure and properties of these complexes depend on the processing conditions.

  4. Fast reconstruction of a bounded ultrasonic beam using acoustically induced piezo-luminescence

    SciTech Connect

    Kersemans, Mathias Lammens, Nicolas; Degrieck, Joris; Van Paepegem, Wim; Smet, Philippe F.

    2015-12-07

    We report on the conversion of ultrasound into light by the process of piezo-luminescence in epoxy with embedded BaSi{sub 2}O{sub 2}N{sub 2}:Eu as active component. We exploit this acoustically induced piezo-luminescence to visualize several cross-sectional slices of the radiation field of an ultrasonic piston transducer (f = 3.3 MHz) in both the near-field and the far-field. Simply combining multiple slices then leads to a fast representation of the 3D spatial radiation field. We have confronted the luminescent results with both scanning hydrophone experiments and digital acoustic holography results, and obtained a good correlation between the different approaches.

  5. Fast reconstruction of a bounded ultrasonic beam using acoustically induced piezo-luminescence

    NASA Astrophysics Data System (ADS)

    Kersemans, Mathias; Smet, Philippe F.; Lammens, Nicolas; Degrieck, Joris; Van Paepegem, Wim

    2015-12-01

    We report on the conversion of ultrasound into light by the process of piezo-luminescence in epoxy with embedded BaSi2O2N2:Eu as active component. We exploit this acoustically induced piezo-luminescence to visualize several cross-sectional slices of the radiation field of an ultrasonic piston transducer (f = 3.3 MHz) in both the near-field and the far-field. Simply combining multiple slices then leads to a fast representation of the 3D spatial radiation field. We have confronted the luminescent results with both scanning hydrophone experiments and digital acoustic holography results, and obtained a good correlation between the different approaches.

  6. Ion beam induced luminescence (IBIL) system for imaging of radiation induced changes in materials

    NASA Astrophysics Data System (ADS)

    Marković, N.; Siketić, Z.; Cosic, D.; Jung, H. K.; Lee, N. H.; Han, W.-T.; Jakšić, M.

    2015-01-01

    The progress of construction on the new IBIL (ion beam induced luminescence) spectrometer installed at the ion microprobe facility of the Ruđer Bošković Institute (RBI) is reported. The IBIL system can be used with beams from either 6.0 MV Tandem Van de Graaff or 1.0 MV Tandetron accelerators. Components of the new apparatus and current experimental set-up are described in detail. Measurements with the new IBIL system were performed using a 2 MeV proton microbeam on three sets of samples. This paper gives a summary of the IBIL arrangement capabilities for various problems, emphasising the potential of this technique for radiation damage studies. Due to the relatively good sensitivity of the IBIL spectrometer, integration into the conventional ion beam analysis (IBA) microbeam setup is shown to be possible.

  7. Radiation-induced luminescence in DNA: Evidence for long-range electron migration

    SciTech Connect

    Al-Kazwini, A.T.; Adams, G.E.; O`Neill, P.; Naylor, M.A.; Fielden, E.M.

    1994-06-01

    The radiation-induced {open_quotes}in-pulse{close_quotes} luminescence emission from solid DNA containing either metronidazole or a highly electron-affinic 5-nitrofuran in the range 3-2000 (w:w) base pairs per additive molecule has been investigated in vacuo at 293 K using electron pulses of energy below 260 keV. The luminescence intensity at 450 nm from DNA decreases with increasing content of the additive in the sample and approaches a limiting level at high concentrations of the additives. At these higher concentrations the limiting value represents about 50% of that observed from DNA alone. It is shown that the efficiency of the additives in reducing the luminescence intensity is dependent upon their redox potential E{sub 7}{sup 1}; this dependence is consistent with these additives acting as electron receptors. It is concluded that the ability of the electron acceptors to reduce the luminescence is related to the electron affinity of E{sub 7}{sup 1} of the acceptors and electron migration distances of at least 300 base pairs are proposed. 30 refs., 2 figs., 1 tab.

  8. Phonon-Induced Dephasing of Excitons in Semiconductor Quantum Dots: Multiple Exciton Generation, Fission, and Luminescence

    NASA Astrophysics Data System (ADS)

    Madrid, Angeline; Kim, Hyeon-Deuk; Habenicht, Bradley; Prezhdo, Oleg

    2010-03-01

    Phonon-induced dephasing processes that govern optical line widths, multiple exciton (ME) generation (MEG), and ME fission (MEF) in semiconductor quantum dots (QDs) are investigated by ab initio molecular dynamics simulation. Using Si QDs as an example, we propose that MEF occurs by phonon-induced dephasing and, for the first time, estimate its time scale to be 100 fs. In contrast, luminescence and MEG dephasing times are all sub-10 fs. Generally, dephasing is faster for higher-energy and higher-order excitons and increased temperatures. MEF is slow because it is facilitated only by low-frequency acoustic modes. Luminescence and MEG couple to both acoustic and optical modes of the QD, as well as ligand vibrations. The detailed atomistic simulation of the dephasing processes advances understanding of exciton dynamics in QDs and other nanoscale materials.

  9. Laser stimulated plasma-induced luminescence for on-air material analysis

    NASA Astrophysics Data System (ADS)

    Veltri, S.; Barberio, M.; Liberatore, C.; Scisciò, M.; Laramée, A.; Palumbo, L.; Legaré, F.; Antici, P.

    2017-01-01

    In this work, we present a method for performing analysis of the chemical composition and optical properties of materials using In-Air Plasma-Induced Luminescence. This is achieved by interaction of a focused high-energy laser with air, an interaction that produces a sub-millimetric plasma. The energetic electrons generated and accelerated in the plasma at energies higher than 5 keV reach the target surface of the sample to be analyzed, causing luminescence emission and plasmonic resonance. Each material is characterized by different chemical and optical properties that can be determined with the above-described technique. As such, our method allows obtaining an exact analysis of the sample, covering surfaces in the range of tens of mm2, in only a few minutes. We show that the acquired information with our method is identical to what obtained with more sophisticated methods, such as SEM-cathodoluminescence and photoluminescence.

  10. Removing Noises Induced by Gamma Radiation in Cerenkov Luminescence Imaging Using a Temporal Median Filter

    PubMed Central

    Li, Yang; Zhan, Yonghua; Kang, Fei; Wang, Jing

    2016-01-01

    Cerenkov luminescence imaging (CLI) can provide information of medical radionuclides used in nuclear imaging based on Cerenkov radiation, which makes it possible for optical means to image clinical radionuclide labeled probes. However, the exceptionally weak Cerenkov luminescence (CL) from Cerenkov radiation is susceptible to lots of impulse noises introduced by high energy gamma rays generating from the decays of radionuclides. In this work, a temporal median filter is proposed to remove this kind of impulse noises. Unlike traditional CLI collecting a single CL image with long exposure time and smoothing it using median filter, the proposed method captures a temporal sequence of CL images with shorter exposure time and employs a temporal median filter to smooth a temporal sequence of pixels. Results of in vivo experiments demonstrated that the proposed temporal median method can effectively remove random pulse noises induced by gamma radiation and achieve a robust CLI image. PMID:27648450

  11. Induced circularly polarized luminescence arising from anion or protein binding to racemic emissive lanthanide complexes

    NASA Astrophysics Data System (ADS)

    Carr, Rachel; Puckrin, Robert; McMahon, Brian K.; Pal, Robert; Parker, David; Pålsson, Lars-Olof

    2014-06-01

    A circularly polarized luminescence (CPL) spectrometer has been built and used to study the binding interaction of lactate and four different proteins with racemic EuIII and TbIII complexes in aqueous solution. Lactate binding gives rise to strong induced CPL spectra, and the observed emission dissymmetry factors vary linearly with enantiomeric composition. Particularly strong induced TbIII CPL also characterizes the binding interaction of alpha-1-acid glycoprotein with a dissociation constant, Kd, of 2.5 μM.

  12. An Ideal System for Analysis and Interpretation of Ion Beam Induced Luminescence

    NASA Astrophysics Data System (ADS)

    Townsend, P. D.; Crespillo, M. L.

    Luminescence is produced during ion beam implantation or ion-solid interaction for most insulators, and contains rich information. Surprisingly, the information extracted is often far from optimum. Rather than summarizing literature work, the focus here is to design an optimized and feasible target chamber that could offer far more information than what has currently been obtained. Such an improved and multi-probe approach opens a range of options to simultaneously record luminescence spectra generated by the ion beam, explore transient and excited state signals via probes of secondary excitation methods (such as ionisation or photo-stimulation). In addition, one may monitor optical absorption, reflectivity and lifetime dependent features, plus stress and polarization factors. A particularly valuable addition to conventional measurements is to have the ability to modulate both the ion beam and the probes. These features allow separation of transient lifetimes, as well as sensing intermediate steps in the defect formation and/or relaxation, and growth of new phases and nanoparticle inclusions. While luminescence methods are the most sensitive probes of defect and imperfection sites in optically active materials, less work has been performed at controlled low and high temperatures. Measurement with controlled cooling or heating of the samples is effective to reveal phase transitions (both of host and inclusions). Furthermore, simultaneous excitations (e.g. ions and photons) at different temperatures may lead to different end-phase or stale structure under extreme ionization conditions and enable fabrication of unique material structures. References to the existing literature will underline that the overall benefits of studying ion beam induced luminescence can be far more fruitful than that has normally been considered.

  13. Pressure-induced luminescence quenching of terbium-coped oxide sulfides

    SciTech Connect

    Gleason, J.K.; Offen, H.W. ); Turley, W.D. )

    1993-03-03

    The photoluminescence of Tb[sup 3+]- and Eu[sup 3+]-doped rare earth oxide sulfides has been studied as a function of pressure. The luminescence intensity and lifetime of the [sup 5]D[sub 3] level of Tb[sup 3+] is quenched by pressure as a result of the pressure-induced red shift of the interconfigurational 4f[sup 7]5d band, in agreement with the energy gap law of radiationless transitions. 33 refs., 7 figs.

  14. GCR-induced Photon Luminescence of the Moon: The Moon as a CR Detector

    NASA Technical Reports Server (NTRS)

    Wilson, Thomas L.; Lee, Kerry; Andersen, Vic

    2007-01-01

    We report on the results of a preliminary study of the GCR-induced photon luminescence of the Moon using the Monte Carlo program FLUKA. The model of the lunar surface is taken to be the chemical composition of soils found at various landing sites during the Apollo and Luna programs, averaged over all such sites to define a generic regolith for the present analysis. This then becomes the target that is bombarded by Galactic Cosmic Rays (GCRs) in FLUKA to determine the photon fluence when there is no sunshine or Earthshine. From the photon fluence we derive the energy spectrum which can be utilized to design an orbiting optical instrument for measuring the GCR-induced luminescence. This is to be distinguished from the gamma-ray spectrum produced by the radioactive decay of its radiogenic constituents lying in the surface and interior. Also, we investigate transient optical flashes from high-energy CRs impacting the lunar surface (boulders and regolith). The goal is to determine to what extent the Moon could be used as a rudimentary CR detector. Meteor impacts on the Moon have been observed for centuries to generate such flashes, so why not CRs?

  15. Sensitive detection of PDT-induced cell damages with luminescent oxygen nanosensors

    NASA Astrophysics Data System (ADS)

    Ma, Hong-Ru; Peng, Hong-shang; You, Fang-tian; Ping, Jian-tao; Zhou, Chao; Guo, Lan-ying

    2016-09-01

    In this work luminescent nanosensors specifically created for intracellular oxygen (ic-O2) were utilized to assess photodynamic therapy (PDT) -induced cell damages. Firstly, ic-O2 was demonstrated to be consumed much faster than extracellular O2 with respective O2 nanosensors. Using the ic-O2 nanosensors, PDT-treated cells with different degree of impairment were then resolved according to the oxygen consumption rate (OCR). The evolving trend of cytotoxicity derived from OCRs was in agreement with cell viability obtained from 3-(4,5-cimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Moreover, the direct damage of PDT on cell mitochondria was successfully detected by monitoring respiration instantly after PDT treatment, which is actually beyond the scope of MTT assay. These results suggest that fluorescence sensing of ic-O2-associated cell respiration is promising and even may become a standardized method, complementary to MTT assay, to evaluate PDT-induced cytotoxicity.

  16. Synthesis, Aggregation Induced Emission and Mechanochromic Luminescence of New β-Diketone Derivatives Bearing Tetraphenylene Moieties.

    PubMed

    Shi, Haijie; Liu, Rui; Zhu, Senqiang; Gong, Qiqi; Shi, Hong; Zhu, Xiaolin; Zhu, Hongjun

    2016-11-01

    A series of β-diketone derivatives bearing tetraphenylene (TPE) moieties were synthesized and characterized. Their photophysical properties were investigated systematically via spectroscopic and theoretical methods. All compounds exhibit broad absorption bands between 300 and 450 nm, which are assigned to the (1)π-π* transition of the conjugated system mixed intramolecular charge-transfer (ICT) transitions. Meanwhile, the emission of these compounds in solution at room temperature (λ em = 458 ~ 509 nm) can be attributed to the (1)π,π*/(1)ICT state. Introduction of freely rotatable TPE to conventional β-diketone luminophors quenches their light emissions in the solutions, but endows these molecules with aggregation-induced emission (AIE) characteristics in the condensed phase due to the restriction of intramolecular rotation. The spectroscopic studies and theoretical calculations indicate that the photophysical properties of these β-diketone derivatives can be tuned by the appended substituents, which would be useful for rational design of AIE compounds with high solid state luminescence performance. Furthermore, these AIE-active compounds exhibited distinct piezofluorochromic properties and switched reversibly upon grinding-fuming. Their photophysical properties have been investigated with the aim to provide a basis for elucidating the structure-property correlations and developing new multi-stimuli responsive luminescent materials.

  17. Time Evolution of Radiation-Induced Luminescence in Terbium-Doped Silicate Glass

    NASA Technical Reports Server (NTRS)

    West, Michael S.; Winfree, William P.

    1996-01-01

    A study was made on two commercially available terbium-doped silicate glasses. There is an increased interest in silicate glasses doped with rare-earth ions for use in high-energy particle detection and radiographic applications. These glasses are of interest due to the fact that they can be formed into small fiber sensors; a property that can be used to increase the spatial resolution of a detection system. Following absorption of radiation, the terbium ions become excited and then emit photons via 4f-4f electronic transitions as they relax back to the ground state. The lifetime of these transitions is on the order of milliseconds. A longer decay component lasting on the order of minutes has also been observed. While radiative transitions in the 4f shell of rare-earth ions are generally well understood by the Judd-Olfelt theory, the pr'esence of a longer luminescence decay component is not. Experimental evidence that the long decay component is due, in part, to the thermal release of trapped charge carriers will be presented. In addition, a theoretical model describing the time evolution of the radiation-induced luminescence will be presented.

  18. Molecular characterisation of camptothecin-induced mutations at the hprt locus in Chinese hamster cells.

    PubMed

    Balestrieri, E; Zanier, R; Degrassi, F

    2001-05-09

    The capacity of the topoisomerase I inhibitor camptothecin (CPT) to induce single locus mutations at the hypoxanthine-guanine phosphoribosyltransferase (hprt) gene and the DNA changes underlying induced mutations were analysed in Chinese hamster ovary cells. Camptothecin treatments increased hprt mutations up to 50-fold over the spontaneous levels at highly cytotoxic doses. Genomic DNA was isolated from 6-thioguanine resistant clones and subjected to multiplex PCR to screen for gross alterations in the gene structure. The molecular analysis revealed that deletion mutants represented 80% of the analysed clones, including total hprt deletion, multiple and single exon deletions. Furthermore, a fraction of the analysed clones showed deletions of more than one exon that were characterised by the absence of non-contiguous exons. These data show that single locus mutations induced by camptothecin are characterised by large deletions or complex rearrangements rather than single base substitutions and suggest that the recombinational repair of camptothecin-induced strand breaks at replication fork may be involved in the generations of these alterations at the chromatin structure level.

  19. Radiation Induced Enhancement of Hydrogen Influence on Luminescent Properties of nc-Si/SiO2 Structures

    NASA Astrophysics Data System (ADS)

    Lisovskyy, Igor; Voitovych, Mariia; Litovchenko, Volodymyr; Voitovych, Vasyl; Nasieka, Iurii; Bratus, Viktor

    2016-12-01

    Using photo-luminescence, infrared spectroscopy, and electron spin resonance technique, the silicon dioxide films with embedded silicon nanocrystals (nc-Si/SiO2 structures) have been investigated after γ-irradiation with the dose 2 × 107 rad and subsequent annealing at 450 °C in hydrogen ambient. For the first time, it was shown that such a radiation-thermal treatment results in significant increase of the luminescence intensity, in a red shift of the photoluminescence spectra, and in disappearance of the electron-spin resonance signal related to silicon broken bonds. This effect has been explained by passivation of silicon broken bonds at the nc-Si-SiO2 interface with hydrogen and by generation of new luminescence centers, these centers being created at elevated temperatures due to transformation of radiation-induced defects.

  20. Multistimuli-Responsive Luminescence of Naphthalazine Based on Aggregation-Induced Emission

    PubMed Central

    Yao, Xiang; Ru, Jia-Xi; Xu, Cong; Liu, Ya-Ming; Dou, Wei; Tang, Xiao-Liang; Zhang, Guo-Lin; Liu, Wei-Sheng

    2015-01-01

    Stimuli-responsive luminescent materials, which are dependent on changes in physical molecular packing modes, have attracted more and more interest over the past ten years. In this study, 2,2-dihydroxy-1,1-naphthalazine was synthesized and shown to exhibit different fluorescence emission in solution and solid states with characteristic aggregation-induced emission (AIE) properties. A remarkable change in the fluorescence of 2,2-dihydroxy-1,1-naphthalazine occurred upon mechanical grinding, heating, or exposure to solvents. According to the characterization by solid-state fluorescence spectroscopy, X-ray crystallography, differential scanning calorimetry, and X-ray powder diffraction, the fluorescence change could be attributed to transitions between two structurally different polymorphs. These significant properties could also give 2,2-dihydroxy-1,1-naphthalazine more potential applications as a multifunctional material. PMID:26478843

  1. Laser-induced breakdown spectrometry in jewellery industry. Part II: quantitative characterisation of goldfilled interface.

    PubMed

    Jurado-López, A; Luque de Castro, M D

    2003-02-06

    A new application of laser-induced breakdown spectrometry (LIBS) and multivariate data analysis, namely partial least-squares regression (PLS) in the jewellery industry is reported. The method was designed for the quantitative characterisation of the interface of goldfilled, a material widely used in costume jewellery fabrication, by monitoring the emission lines of the elements present in the sample, while subjecting the piece to a number of laser pulses. The method also provides quantitative information about the composition of a given layer of the material of a special interest at the interface in order to know the existence of diffusion phenomena.

  2. ZnO Luminescence and scintillation studied via photoexcitation, X-ray excitation, and gamma-induced positron spectroscopy

    NASA Astrophysics Data System (ADS)

    Ji, J.; Colosimo, A. M.; Anwand, W.; Boatner, L. A.; Wagner, A.; Stepanov, P. S.; Trinh, T. T.; Liedke, M. O.; Krause-Rehberg, R.; Cowan, T. E.; Selim, F. A.

    2016-08-01

    The luminescence and scintillation properties of ZnO single crystals were studied by photoluminescence and X-ray-induced luminescence (XRIL) techniques. XRIL allowed a direct comparison to be made between the near-band emission (NBE) and trap emissions providing insight into the carrier recombination efficiency in the ZnO crystals. It also provided bulk luminescence measurements that were not affected by surface states. The origin of a green emission, the dominant trap emission in ZnO, was then investigated by gamma-induced positron spectroscopy (GIPS) - a unique defect spectroscopy method that enables positron lifetime measurements to be made for a sample without contributions from positron annihilation in the source materials. The measurements showed a single positron decay curve with a 175 ps lifetime component that was attributed to Zn vacancies passivated by hydrogen. Both oxygen vacancies and hydrogen-decorated Zn vacancies were suggested to contribute to the green emission. By combining scintillation measurements with XRIL, the fast scintillation in ZnO crystals was found to be strongly correlated with the ratio between the defect luminescence and NBE. This study reports the first application of GIPS to semiconductors, and it reveals the great benefits of the XRIL technique for the study of emission and scintillation properties of materials.

  3. ZnO Luminescence and scintillation studied via photoexcitation, X-ray excitation, and gamma-induced positron spectroscopy

    PubMed Central

    Ji, J.; Colosimo, A. M.; Anwand, W.; Boatner, L. A.; Wagner, A.; Stepanov, P. S.; Trinh, T. T.; Liedke, M. O.; Krause-Rehberg, R.; Cowan, T. E.; Selim, F. A.

    2016-01-01

    The luminescence and scintillation properties of ZnO single crystals were studied by photoluminescence and X-ray-induced luminescence (XRIL) techniques. XRIL allowed a direct comparison to be made between the near-band emission (NBE) and trap emissions providing insight into the carrier recombination efficiency in the ZnO crystals. It also provided bulk luminescence measurements that were not affected by surface states. The origin of a green emission, the dominant trap emission in ZnO, was then investigated by gamma-induced positron spectroscopy (GIPS) - a unique defect spectroscopy method that enables positron lifetime measurements to be made for a sample without contributions from positron annihilation in the source materials. The measurements showed a single positron decay curve with a 175 ps lifetime component that was attributed to Zn vacancies passivated by hydrogen. Both oxygen vacancies and hydrogen-decorated Zn vacancies were suggested to contribute to the green emission. By combining scintillation measurements with XRIL, the fast scintillation in ZnO crystals was found to be strongly correlated with the ratio between the defect luminescence and NBE. This study reports the first application of GIPS to semiconductors, and it reveals the great benefits of the XRIL technique for the study of emission and scintillation properties of materials. PMID:27550235

  4. ZnO Luminescence and scintillation studied via photoexcitation, X-ray excitation, and gamma-induced positron spectroscopy.

    PubMed

    Ji, J; Colosimo, A M; Anwand, W; Boatner, L A; Wagner, A; Stepanov, P S; Trinh, T T; Liedke, M O; Krause-Rehberg, R; Cowan, T E; Selim, F A

    2016-08-23

    The luminescence and scintillation properties of ZnO single crystals were studied by photoluminescence and X-ray-induced luminescence (XRIL) techniques. XRIL allowed a direct comparison to be made between the near-band emission (NBE) and trap emissions providing insight into the carrier recombination efficiency in the ZnO crystals. It also provided bulk luminescence measurements that were not affected by surface states. The origin of a green emission, the dominant trap emission in ZnO, was then investigated by gamma-induced positron spectroscopy (GIPS) - a unique defect spectroscopy method that enables positron lifetime measurements to be made for a sample without contributions from positron annihilation in the source materials. The measurements showed a single positron decay curve with a 175 ps lifetime component that was attributed to Zn vacancies passivated by hydrogen. Both oxygen vacancies and hydrogen-decorated Zn vacancies were suggested to contribute to the green emission. By combining scintillation measurements with XRIL, the fast scintillation in ZnO crystals was found to be strongly correlated with the ratio between the defect luminescence and NBE. This study reports the first application of GIPS to semiconductors, and it reveals the great benefits of the XRIL technique for the study of emission and scintillation properties of materials.

  5. Ligand Induced Circular Dichroism and Circularly Polarized Luminescence in CdSe Quantum Dots

    PubMed Central

    Tohgha, Urice; Deol, Kirandeep K.; Porter, Ashlin G.; Bartko, Samuel G.; Choi, Jung Kyu; Leonard, Brian M.; Varga, Krisztina; Kubelka, Jan; Muller, Gilles; Balaz, Milan

    2014-01-01

    Chiral thiol capping ligands L- and D-cysteines induced modular chiroptical properties in achiral cadmium selenide quantum dots (CdSe QDs). Cys-CdSe prepared from achiral oleic acid capped CdSe by post-synthetic ligand exchange displayed size-dependent electronic circular dichroism (CD) and circularly polarized luminescence (CPL). Opposite CPL signals were measured for the CdSe QDs capped with D- and L-cysteine. The CD profile and CD anisotropy varied with size of CdSe nanocrystals with largest anisotropy observed for CdSe nanoparticles of 4.4 nm. Magic angle spinning solid state NMR (MAS ssNMR) experiments suggested bidentate interaction between cysteine and the surface of CdSe. Density functional theory (DFT) calculations verified that attachment of L- and D-cysteine to the surface of model (CdSe)13 nanoclusters induces measurable opposite CD signals for the exitonic band of the nanocluster. The chirality was induced by the hybridization of highest occupied CdSe molecular orbitals with those of the chiral ligand. PMID:24200288

  6. X-ray irradiation-induced formation of luminescent silver clusters in nanoporous matrices.

    PubMed

    Coutino-Gonzalez, Eduardo; Grandjean, Didier; Roeffaers, Maarten; Kvashnina, Kristina; Fron, Eduard; Dieu, Bjorn; De Cremer, Gert; Lievens, Peter; Sels, Bert; Hofkens, Johan

    2014-02-09

    We report the formation of luminescent silver clusters in zeolites by a fast, highly accurate, and controlled activation of silver ions entrapped in sodalite cages of LTA and FAU zeolites using high-brilliance soft X-rays. The activated luminescent samples were investigated by employing a combination of stationary and time-resolved spectroscopic techniques.

  7. Transient luminescence induced by electrical refilling of charge carrier traps of dislocation network at hydrophilically bonded Si wafers interface

    SciTech Connect

    Bondarenko, Anton; Vyvenko, Oleg

    2014-02-21

    Dislocation network (DN) at hydrophilically bonded Si wafers interface is placed in space charge region (SCR) of a Schottky diode at a depth of about 150 nm from Schottky electrode for simultaneous investigation of its electrical and luminescent properties. Our recently proposed pulsed traps refilling enhanced luminescence (Pulsed-TREL) technique based on the effect of transient luminescence induced by refilling of charge carrier traps with electrical pulses is further developed and used as a tool to establish DN energy levels responsible for D1 band of dislocation-related luminescence in Si (DRL). In present work we do theoretical analysis and simulation of traps refilling kinetics dependence on refilling pulse magnitude (Vp) in two levels model: shallow and deep. The influence of initial charge state of deep level on shallow level occupation-Vp dependence is discussed. Characteristic features predicted by simulations are used for Pulsed-TREL experimental results interpretation. We conclude that only shallow (∼0.1 eV from conduction and valence band) energetic levels in the band gap participate in D1 DRL.

  8. Quantum Interference between Energy Absorption Processes of Molecular Exciton and Interface Plasmons on Luminescence Induced by Scanning Tunneling Microscopy

    NASA Astrophysics Data System (ADS)

    Miwa, Kuniyuki; Imasa, Hiroshi; Sakaue, Mamoru; Kasai, Hideaki; Kim, Yousoo

    2015-03-01

    Luminescence induced by the tunneling current of a scanning tunneling microscope (STM) from molecule-covered metal surfaces is attributed to radiative decays of molecules and interface plasmons localized near the tip-substrate gap region. Since the dynamics of molecule and interface plasmons strongly influence each other, the interplay between these dynamics gives rise to peculiar phenomena originating from quantum many-body effects. In this study, we develop the effective model of the system and investigate the luminescence properties using the nonequilibrium Green's function method. The results show that, in addition to the dynamics of molecule, energy reabsorption by interface plasmons have a critical role in determining the luminescence spectral profile of interface plasmons. The additional peak structure arises owing to the interference between these energy absorption processes. Origin of prominent peak and dip structures observed in recent experiments are identified by the developed theory. The details of the interference effects on the luminescence properties will be discussed. This work was supported by JSPS KAKENHI Grant Number 26886013.

  9. Delayed luminescence to monitor programmed cell death induced by berberine on thyroid cancer cells

    NASA Astrophysics Data System (ADS)

    Scordino, Agata; Campisi, Agata; Grasso, Rosaria; Bonfanti, Roberta; Gulino, Marisa; Iauk, Liliana; Parenti, Rosalba; Musumeci, Francesco

    2014-11-01

    Correlation between apoptosis and UVA-induced ultraweak photon emission delayed luminescence (DL) from tumor thyroid cell lines was investigated. In particular, the effects of berberine, an alkaloid that has been reported to have anticancer activities, on two cancer cell lines were studied. The FTC-133 and 8305C cell lines, as representative of follicular and anaplastic thyroid human cancer, respectively, were chosen. The results show that berberine is able to arrest cell cycle and activate apoptotic pathway as shown in both cell lines by deoxyribonucleic acid fragmentation, caspase-3 cleavage, p53 and p27 protein overexpression. In parallel, changes in DL spectral components after berberine treatment support the hypothesis that DL from human cells originates mainly from mitochondria, since berberine acts especially at the mitochondrial level. The decrease of DL blue component for both cell lines could be related to the decrease of intra-mitochondrial nicotinamide adenine dinucleotide and may be a hallmark of induced apoptosis. In contrast, the response in the red spectral range is different for the two cell lines and may be ascribed to a different iron homeostasis.

  10. NIR femtosecond laser induced hyper-Rayleigh scattering and luminescence from silver nanoprisms.

    PubMed

    Jain, Beena; Srivastava, Arvind Kumar; Uppal, Abha; Gupta, Pradeep Kumar; Das, Kaustuv

    2010-09-01

    The nonlinear response of silver nanoprisms (edge length 40 +/- 5 nm and thickness 4.5 +/- 0.5 nm) was studied by exciting with NIR femtosecond pulses (780-880 nm). These nanostructures were observed to generate hyper-Rayleigh scattering (HRS) and broadband luminescence. While HRS showed the expected second order power dependence, the luminescence was observed to follow a third order excitation power dependence. Both HRS and luminescence were observed to be dipolar in nature. The first hyperpolarizability of the nanoprisms was found to be an order of magnitude higher than approximately 15 nm sized nanospheres.

  11. Insights on proximity effect and multiphoton induced luminescence from gold nanospheres in far field optical microscopy

    SciTech Connect

    Borglin, Johan; Guldbrand, Stina; Evenbratt, Hanne; Kirejev, Vladimir; Ericson, Marica B.; Grönbeck, Henrik

    2015-12-07

    Gold nanoparticles can be visualized in far-field multiphoton laser-scanning microscopy (MPM) based on the phenomena of multiphoton induced luminescence (MIL). This is of interest for biomedical applications, e.g., for cancer diagnostics, as MPM allows for working in the near-infrared (NIR) optical window of tissue. It is well known that the aggregation of particles causes a redshift of the plasmon resonance, but its implications for MIL applying far-field MPM should be further exploited. Here, we explore MIL from 10 nm gold nanospheres that are chemically deposited on glass substrates in controlled coverage gradients using MPM operating in NIR range. The substrates enable studies of MIL as a function of inter-particle distance and clustering. It was shown that MIL was only detected from areas on the substrates where the particle spacing was less than one particle diameter, or where the particles have aggregated. The results are interpreted in the context that the underlying physical phenomenon of MIL is a sequential two-photon absorption process, where the first event is driven by the plasmon resonance. It is evident that gold nanospheres in this size range have to be closely spaced or clustered to exhibit detectable MIL using far-field MPM operating in the NIR region.

  12. Hard X-ray-induced optical luminescence via biomolecule-directed metal clusters.

    PubMed

    Osakada, Yasuko; Pratx, Guillem; Sun, Conroy; Sakamoto, Masanori; Ahmad, Moiz; Volotskova, Olga; Ong, Qunxiang; Teranishi, Toshiharu; Harada, Yoshie; Xing, Lei; Cui, Bianxiao

    2014-04-07

    Here, we demonstrate that biomolecule-directed metal clusters are applicable in the study of hard X-ray excited optical luminescence, promising a new direction in the development of novel X-ray-activated imaging probes.

  13. Persistent luminescence induced by near infra-red photostimulation in chromium-doped zinc gallate for in vivo optical imaging

    NASA Astrophysics Data System (ADS)

    Sharma, Suchinder K.; Gourier, Didier; Teston, Eliott; Scherman, Daniel; Richard, Cyrille; Viana, Bruno

    2017-01-01

    The analysis of the optical spectroscopy of the Cr3+ doped spinel was initiated by Prof. Georges Boulon more than twenty years ago. More recently persistent luminescence nanoparticles of Cr doped zinc gallate have found interest for in vivo imaging of small animals. Here we evaluated near infra-red (NIR) excitation (or NIR photostimulation) via photo-transfer mechanism as an additional tool for in vivo optical imaging. Investigation of the persistent luminescence induced by NIR photostimulation is studied after either a primary UV (band-to-band excitation) or visible irradiation (direct Cr 3d-3d excitation). UV or visible pre-excited ZnGa2O4:Cr (ZGO:Cr) nanoparticles are kept active during several days thanks to deep traps (with depths 1 eV-1.2 eV) observed in these samples which can be probed through thermally stimulated luminescence (TSL) technique showing glow curve maximums at 470 K and 530 K upon visible light excitation. These deep traps are stable at room temperature but can be emptied by NIR light photostimulation. Experiments were carried out to study the photostimulation induced trapping-detrapping in the ZGO:Cr phosphor. Photostimulation was also tested in vivo for small animal optical imaging to offer new perspectives and modalities.

  14. Defects in sodalite-group minerals determined from X-ray-induced luminescence

    NASA Astrophysics Data System (ADS)

    Finch, Adrian A.; Friis, Henrik; Maghrabi, Mufeed

    2016-07-01

    The luminescence spectra of a suite of natural sodium framework silicates including four different sodalite variants and tugtupite have been collected during X-ray irradiation as a function of temperature between 20 and 673 K. The origin of the emission bands observed in these samples is attributed to F-centres (360 nm), paramagnetic oxygen defects (400 and 450 nm), S2 - ions (620 nm) and tetrahedral Fe3+ (730 nm). Luminescence in the yellow (550 nm) is tentatively attributed to Mn2+, and red luminescence in Cr-rich pink sodalite is possibly from Cr3+ activation. Sudden reduction in luminescence intensities of emission centres was observed for all minerals in the 60-120 K range. Since it is common to all the sodalite-group minerals, we infer it is a feature of the aluminosilicate framework. Sodalite luminescence has responses from substitutions on the framework (e.g. paramagnetic oxygen defects, Fe3+) which give sodalite properties akin to other framework silicates such as feldspar and quartz. However, the presence of the sodalite cage containing anions (such as F-centres, S2 - ions) imparts additional properties akin to alkali halides. The possibility of coupling between Fe3+ and S2 - is discussed. The overall luminescence behaviour of sodalite group can be understood in terms of competition between these centre types.

  15. Luminescence decay of porous silicon

    NASA Astrophysics Data System (ADS)

    Chen, X.; Uttamchandani, D.; Sander, D.; O'Donnell, K. P.

    1993-04-01

    The luminescence decay pattern of porous silicon samples prepared by electrochemical etching is characterised experimentally by a non-exponential profile, a strong dependence on temperature and an absence of spectral diffusion. We describe this luminescence as carrier-dopping-assisted recombination. Following the correlation function approach to non-dispersive transport developed by Scher and co-workers [Physics Today 41 (1991) 26], we suggest a simple derivation of analytical functions which accurately describes the anomalous luminescence decay of porous silicon, and show that this model includes exponential and Kohlrausch [Pogg. Ann. Phys. 119 (1863) 352] (stretched-exponential) relaxations as special cases.

  16. Osteogenic, stem cell and molecular characterisation of the human induced membrane from extremity bone defects

    PubMed Central

    Ode, G.; Hoelscher, G.; Ingram, J.; Bethea, S.; Bosse, M. J.

    2016-01-01

    Objectives The biomembrane (induced membrane) formed around polymethylmethacrylate (PMMA) spacers has value in clinical applications for bone defect reconstruction. Few studies have evaluated its cellular, molecular or stem cell features. Our objective was to characterise induced membrane morphology, molecular features and osteogenic stem cell characteristics. Methods Following Institutional Review Board approval, biomembrane specimens were obtained from 12 patient surgeries for management of segmental bony defects (mean patient age 40.7 years, standard deviation 14.4). Biomembranes from nine tibias and three femurs were processed for morphologic, molecular or stem cell analyses. Gene expression was determined using the Affymetrix GeneChip Operating Software (GCOS). Molecular analyses compared biomembrane gene expression patterns with a mineralising osteoblast culture, and gene expression in specimens with longer spacer duration (> 12 weeks) with specimens with shorter durations. Statistical analyses used the unpaired student t-test (two tailed; p < 0.05 was considered significant). Results Average PMMA spacer in vivo time was 11.9 weeks (six to 18). Trabecular bone was present in 33.3% of the biomembrane specimens; bone presence did not correlate with spacer duration. Biomembrane morphology showed high vascularity and collagen content and positive staining for the key bone forming regulators, bone morphogenetic protein 2 (BMP2) and runt-related transcription factor 2 (RUNX2). Positive differentiation of cultured biomembrane cells for osteogenesis was found in cells from patients with PMMA present for six to 17 weeks. Stem cell differentiation showed greater variability in pluripotency for osteogenic potential (70.0%) compared with chondrogenic or adipogenic potentials (100% and 90.0%, respectively). Significant upregulation of BMP2 and 6, numerous collagens, and bone gla protein was present in biomembrane compared with the cultured cell line. Biomembranes with

  17. Luminescence sensitivity changes in natural quartz induced by high temperature annealing: a high frequency EPR and OSL study

    NASA Astrophysics Data System (ADS)

    Poolton, N. R. J.; Smith, G. M.; Riedi, P. C.; Bulur, E.; Bøtter-Jensen, L.; Murray, A. S.; Adrian, M.

    2000-04-01

    Quartz undergoes very significant luminescence sensitivity changes after high temperature annealing (0-1200 °C), with particular enhancement occurring between the phase transition temperatures 573 and 870 °C. In order to understand why this occurs, high frequency electron paramagnetic resonance (EPR), operating at 90 GHz, has been used to monitor the structure and population of defects in natural sedimentary quartz, following annealing and icons/Journals/Common/gamma" ALT="gamma" ALIGN="TOP"/> -irradiation. The results are compared with the optically stimulated luminescence (OSL) data of the same samples. It is shown that: (i) the structure and population of the dominant [AlO4 ]0 recombination centres are largely unaffected by the annealing process; (ii) the oxygen vacancy E´ centres are destroyed when annealed at temperatures between the phase transitions and; (iii) the numbers of both [TiO4 /H+ ]0 and [TiO4 /Li+ ]0 donors increase between 400 and 700 °C. Photo-EPR spectra are presented, providing evidence that both the Ti associated donors and Al acceptors are directly involved in the OSL process. The heat-induced changes in the population of these EPR defects is mirrored in part by the change in the luminescence sensitivity of several OSL components. Evidence is also presented suggesting that E´ may act as non-radiative centres competing in the OSL process.

  18. Nitrite ion-induced fluorescence quenching of luminescent BSA-Au(25) nanoclusters: mechanism and application.

    PubMed

    Unnikrishnan, Binesh; Wei, Shih-Chun; Chiu, Wei-Jane; Cang, Jinshun; Hsu, Pang-Hung; Huang, Chih-Ching

    2014-05-07

    Fluorescence quenching is an interesting phenomenon which is highly useful in developing fluorescence based sensors. A thorough understanding of the fluorescence quenching mechanism is essential to develop efficient sensors. In this work, we investigate different aspects governing the nitrite ion-induced fluorescence quenching of luminescent bovine serum albumin stabilized gold nanoclusters (BSA-Au NCs) and their application for detection of nitrite in urine. The probable events leading to photoluminescence (PL) quenching by nitrite ions were discussed on the basis of the results obtained from ultraviolet-visible (UV-Vis) absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), fluorescence measurements, circular dichroism (CD) spectroscopy, zeta potential and dynamic light scattering (DLS) studies. These studies suggested that PL quenching mainly occurred through the oxidation of Au(0) atoms to Au(i) atoms in the core of BSA-Au NCs mediated by nitrite ions. The interference caused by certain species such as Hg(2+), Cu(2+), CN(-), S(2-), glutathione, cysteine, etc. during the nitrite determination by fluorescence quenching was eliminated by using masking agents and optimising the conditions. Based on these findings we proposed a BSA-Au NC-modified membrane based sensor which would be more convenient for the real life applications such as nitrite detection in urine samples. The BSA-Au NC-modified nitrocellulose membrane (NCM) enabled the detection of nitrite at a level as low as 100 nM in aqueous solutions. This Au NC-based paper probe was validated to exhibit good performance for nitrite analysis in environmental water and urine samples, which makes it useful in practical applications.

  19. Characterisation of antibody responses in pigs induced by recombinant oncosphere antigens from Taenia solium.

    PubMed

    Jayashi, César M; Gonzalez, Armando E; Castillo Neyra, Ricardo; Kyngdon, Craig T; Gauci, Charles G; Lightowlers, Marshall W

    2012-12-14

    Recombinant antigens cloned from the oncosphere life cycle stage of the cestode parasite Taenia solium (T. solium) have been proven to be effective as vaccines for protecting pigs against infections with T. solium. Previous studies have defined three different host protective oncosphere antigens, TSOL18, TSOL16 and TSOL45. In this study, we evaluated the potential for combining the antigens TSOL16 and TSOL18 as a practical vaccine. Firstly, in a laboratory trial, we compared the immunogenicity of the combined antigens (TSOL16/18) versus the immunogenicity of the antigens separately. Secondly, in a field trial, we tested the ability of the TSOL16/18 vaccine to induce detectable antibody responses in animals living under environmental stress and traditionally reared in areas where T. solium cysticercosis is endemic; and finally, we characterised the immune response of the study population. Pigs of 8-16 weeks of age were vaccinated with 200 μg each of TSOL16 and TSOL18, plus 5mg of Quil-A. Specific total IgG, IgG(1) and IgG(2) antibody responses induced by TSOL16 and TSOL18 were determined with ELISA. The immunogenicity of both antigens was retained in the combined TSOL16/18 vaccine. The combined vaccine TSOL16/18 induced detectable specific anti-TSOL18 antibody responses in 100% (113/113) and specific anti-TSOL16 in 99% (112/113) of the vaccinated animals measured at 2 weeks following the booster vaccination. From the two IgG antibody subtypes analysed we found there was stronger response to IgG(2).

  20. Generation of cavitation luminescence by laser-induced exothermic chemical reaction

    SciTech Connect

    Jung Park, Han; Diebold, Gerald J.

    2013-08-14

    Absorption of high power laser radiation by aqueous carbon suspensions is known to result in the formation of highly compressed bubbles of hydrogen and carbon monoxide through the endothermic carbon-steam reaction. The bubbles expand rapidly, overreaching their equilibrium diameter, and then collapse tens to hundreds of microseconds after formation to give a flash of radiation. Here we report on the effects of laser-initiated exothermic chemical reaction on cavitation luminescence. Experiments with hydrogen peroxide added to colloidal carbon suspensions show that both the time of the light flash following the laser pulse and the intensity of luminescence increase with hydrogen peroxide concentration, indicating that large, highly energetic gas bubbles are produced. Additional experiments with colloidal carbon suspensions show the effects of high pressure on the luminescent intensity and its time of appearance following firing of the laser.

  1. Precursor Luminescence near the Collapse of Laser-Induced Bubbles in Alkali-Salt Solutions

    PubMed Central

    Chu, Han-Ching; Vo, Sonny; Williams, Gary A.

    2014-01-01

    A precursor luminescence pulse consisting of atomic line emission is observed as much as 150 nanoseconds prior to the collapse point of laser-created bubbles in alkali-metal solutions. The timing of the emission from neutral Na, Li, and K atoms is strongly dependent on the salt concentration, which appears to result from resonant radiation trapping by the alkali atoms in the bubble. The alkali emission ends at the onset of the blackbody luminescence pulse at the bubble collapse point, and the duration of the blackbody pulse is found to be reduced by up to 30% as the alkali-salt concentration is increased. PMID:19519032

  2. Towards the differentiation of non-treated and treated corundum minerals by ion-beam-induced luminescence and other complementary techniques.

    PubMed

    Calvo del Castillo, H; Deprez, N; Dupuis, T; Mathis, F; Deneckere, A; Vandenabeele, P; Calderón, T; Strivay, D

    2009-06-01

    Differentiation of treated and non-treated gemstones is a chief concern for major jewellery import companies. Low-quality corundum specimens coming from Asia appear to be often treated with heat, BeO or flux in order to enhance their properties as precious minerals. A set of corundum samples, rubies and sapphires from different origins, both treated and non-treated has been analysed at the Centre Européen d'Archéométrie, with ion-beam-induced luminescence (IBIL) and other complementary techniques such as Raman, proton-induced X-ray emission (PIXE), and proton-induced gamma-ray emission (PIGE). IBIL, also known as ionoluminescence, has been used before to detect impurities or defects inside synthetic materials and natural minerals; its use for the discrimination of gemstone simulants or synthetic analogues has been elsewhere discussed (Cavenago-Bignami Moneta, Gemología, Tomo I Piedras preciosas, perlas, corales, marfil. Ediciones Omega, Barcelona, 1991). PIXE has been frequently applied in the archaeometric field for material characterisation and provenance studies of minerals (Hughes, Ruby & sapphire. RWH Publishing, Fallbrook, 1997; Calvo del Castillo et al., Anal Bioanal Chem 387:869-878, 2007; Calligaro et al., NIM-B 189:320-327, 2002) and PIGE complements the elemental analysis by detecting light elements in these materials such as-and lighter than-sodium that cannot be identified with the PIXE technique (Sanchez et al., NIM-B 130:682-686, 1997; Emmett et al., Gems Gemology 39:84-135, 2003). The micro-Raman technique has also been used complementarily to ion beam analysis techniques for mineral characterisation (Novak et al., Appl Surf Sci 231-232:917-920, 2004). The aim of this study is to provide new means for systematic analysis of corundum gemstone-quality mineral, alternative to the traditional gemmologic methods; for this purpose, a Spanish jewellery import company supplied us with a number of natural corundum samples coming from different places

  3. A high-content platform to characterise human induced pluripotent stem cell lines

    PubMed Central

    Leha, Andreas; Moens, Nathalie; Meleckyte, Ruta; Culley, Oliver J.; Gervasio, Mia K.; Kerz, Maximilian; Reimer, Andreas; Cain, Stuart A.; Streeter, Ian; Folarin, Amos; Stegle, Oliver; Kielty, Cay M.; Durbin, Richard; Watt, Fiona M.; Danovi, Davide

    2016-01-01

    Induced pluripotent stem cells (iPSCs) provide invaluable opportunities for future cell therapies as well as for studying human development, modelling diseases and discovering therapeutics. In order to realise the potential of iPSCs, it is crucial to comprehensively characterise cells generated from large cohorts of healthy and diseased individuals. The human iPSC initiative (HipSci) is assessing a large panel of cell lines to define cell phenotypes, dissect inter- and intra-line and donor variability and identify its key determinant components. Here we report the establishment of a high-content platform for phenotypic analysis of human iPSC lines. In the described assay, cells are dissociated and seeded as single cells onto 96-well plates coated with fibronectin at three different concentrations. This method allows assessment of cell number, proliferation, morphology and intercellular adhesion. Altogether, our strategy delivers robust quantification of phenotypic diversity within complex cell populations facilitating future identification of the genetic, biological and technical determinants of variance. Approaches such as the one described can be used to benchmark iPSCs from multiple donors and create novel platforms that can readily be tailored for disease modelling and drug discovery. PMID:26608109

  4. A high-content platform to characterise human induced pluripotent stem cell lines.

    PubMed

    Leha, Andreas; Moens, Nathalie; Meleckyte, Ruta; Culley, Oliver J; Gervasio, Mia K; Kerz, Maximilian; Reimer, Andreas; Cain, Stuart A; Streeter, Ian; Folarin, Amos; Stegle, Oliver; Kielty, Cay M; Durbin, Richard; Watt, Fiona M; Danovi, Davide

    2016-03-01

    Induced pluripotent stem cells (iPSCs) provide invaluable opportunities for future cell therapies as well as for studying human development, modelling diseases and discovering therapeutics. In order to realise the potential of iPSCs, it is crucial to comprehensively characterise cells generated from large cohorts of healthy and diseased individuals. The human iPSC initiative (HipSci) is assessing a large panel of cell lines to define cell phenotypes, dissect inter- and intra-line and donor variability and identify its key determinant components. Here we report the establishment of a high-content platform for phenotypic analysis of human iPSC lines. In the described assay, cells are dissociated and seeded as single cells onto 96-well plates coated with fibronectin at three different concentrations. This method allows assessment of cell number, proliferation, morphology and intercellular adhesion. Altogether, our strategy delivers robust quantification of phenotypic diversity within complex cell populations facilitating future identification of the genetic, biological and technical determinants of variance. Approaches such as the one described can be used to benchmark iPSCs from multiple donors and create novel platforms that can readily be tailored for disease modelling and drug discovery.

  5. In situ formation and characterisation of singly ionised atomic europium in rare gas matrices—Luminescence spectroscopy and MP2 calculations

    SciTech Connect

    Byrne, Owen; Davis, Barry; McCaffrey, John G.

    2015-02-07

    Irradiation of atomic europium isolated in the solid rare gases, with low intensity laser excitation of the y{sup 8}P←a{sup 8}S resonance transition at ca. 465 nm, is found to produce singly charged europium cations (Eu{sup +}) in large amounts in xenon and in smaller amounts in argon. Confirmation of the formation of matrix-isolated Eu{sup +} is obtained from characteristic absorption bands in the UV and in the visible spectral regions. The luminescence produced with excitation of the cation bands is presented in greatest detail for Eu/Xe and assigned. Excitation of the 4f{sup 7}({sup 8}S{sub 7/2})6p{sub 3/2} absorption bands of Eu{sup +} between 390 and 410 nm produces emission which is quite distinct from that resulting from excitation of the 4f{sup 7}({sup 8}S{sub 7/2})6p{sub 1/2} absorption (430 to 450 nm) features. The latter consists of narrow, resolved emission bands with Stokes shifts ten times smaller than the former. The observed spectral differences are discussed in relation to the different spatial symmetries of the p{sub 3/2} and p{sub 1/2} orbitals in these j-j coupled (7/2, 3/2){sub J} and the (7/2, 1/2){sub J} levels. Møller-Plesset calculations are conducted to obtain the molecular parameters of the neutral Eu-RG and cationic Eu{sup +}-RG diatomics (RG = Ar, Kr, Xe). From the short bond lengths and the strong binding energies obtained for the Eu{sup +}-RG species, these values suggest the isolation of the ion in small, possibly interstitial sites especially in xenon. In contrast, but consistent with previous work [O. Byrne and J. G. McCaffrey, J. Chem. Phys. 134, 124501 (2011)], the interaction potentials calculated herein for the Eu-RG diatomics suggest that the neutral Eu atom occupies tetra-vacancy (tv) and hexa-vacancy (hv) sites in the solid rare gas hosts. Possible reasons for the facile production of Eu{sup +} in the solid rare gases are discussed. The mechanism proposed is that atomic europium is also acting as an electron acceptor

  6. Luminescence nanothermometry

    NASA Astrophysics Data System (ADS)

    Jaque, Daniel; Vetrone, Fiorenzo

    2012-07-01

    The current status of luminescence nanothermometry is reviewed in detail. Based on the main parameters of luminescence including intensity, bandwidth, bandshape, polarization, spectral shift and lifetime, we initially describe and compare the different classes of luminescence nanothermometry. Subsequently, the various luminescent materials used in each case are discussed and the mechanisms at the root of the luminescence thermal sensitivity are described. The most important results obtained in each case are summarized and the advantages and disadvantages of these approaches are discussed.The current status of luminescence nanothermometry is reviewed in detail. Based on the main parameters of luminescence including intensity, bandwidth, bandshape, polarization, spectral shift and lifetime, we initially describe and compare the different classes of luminescence nanothermometry. Subsequently, the various luminescent materials used in each case are discussed and the mechanisms at the root of the luminescence thermal sensitivity are described. The most important results obtained in each case are summarized and the advantages and disadvantages of these approaches are discussed. This work was supported by the Universidad Autónoma de Madrid and Comunidad Autónoma de Madrid (Project S2009/MAT-1756), by the Spanish Ministerio de Educacion y Ciencia (MAT2010-16161) and by Caja Madrid Foundation.

  7. Coordination-Induced Syntheses of Two Hybrid Framework Iodides: A Thermochromic Luminescent Thermometer.

    PubMed

    Zhang, Ren-Chun; Wang, Jun-Jie; Zhang, Jing-Chao; Wang, Meng-Qi; Sun, Min; Ding, Feng; Zhang, Dao-Jun; An, Yong-Lin

    2016-08-01

    Two new 3D hybrid framework iodides, Hmta[(Hmta)Ag4I4] (1; Hmta = hexamethylenetetramine) and [(Hmta)2Ag8I6]I2 (2), have been synthesized under solvothermal conditions. Compound 1 consists of a neutral 3D framework built up from alternation of the tetrahedral Ag4I4 unit and Hmta with dia-b topology. Compound 2 features a 3D cationic framework with flu topology, constructed by cationic [Ag8I6](2+) units linked with Hmta. Tetrahedral Hmta plays crucial structure-directing roles in the formation of these 3D frameworks with high symmetry. The temperature-dependent photoluminescent measurement reveals luminescent thermochromism of the compounds, the emission maximum of which shows a gradual blue shift with increasing temperature. The results indicate that 1 is a promising wavelength- and intensity-dependent luminescent thermometer applicable in two different temperature ranges.

  8. Preliminary results on time-resolved ion beam induced luminescence applied to the provenance study of lapis lazuli

    NASA Astrophysics Data System (ADS)

    Czelusniak, C.; Palla, L.; Massi, M.; Carraresi, L.; Giuntini, L.; Re, A.; Lo Giudice, A.; Pratesi, G.; Mazzinghi, A.; Ruberto, C.; Castelli, L.; Fedi, M. E.; Liccioli, L.; Gueli, A.; Mandò, P. A.; Taccetti, F.

    2016-03-01

    This work will present preliminary results concerning the use of time-resolved ion beam induced luminescence applied to provenance studies of lapis lazuli. Measurements were performed at the pulsed beam facility at LABEC laboratory in Florence. Lapis lazuli is a semi-precious gemstone, used as ornament since the early civilizations that can be found in few places on Earth. The importance of this work lies in understanding the origin of various samples of lapis lazuli, from which it may be possible to gain insight into trade routes from ancient times. The samples studied in this work originated from Chile, Afghanistan, Tajikistan, Myanmar, and Siberia. The stones were irradiated with 3 MeV protons and the resulting luminescence was detected by a photomultiplier tube, whose output was acquired using a sampling digitizer VME module (CAEN/V1720). Wavelength discrimination was performed at 430 nm utilizing a range of beam currents. The results showed that, by changing the beam current intensity, one can study different features of lapis lazuli, and this may aid in distinguishing lapis lazuli from different provenances.

  9. In situ ion-beam-induced luminescence analysis for evaluating a micrometer-scale radio-photoluminescence glass dosimeter

    NASA Astrophysics Data System (ADS)

    Kawabata, Shunsuke; Kada, Wataru; Parajuli, Raj Kumar; Matsubara, Yoshinori; Sakai, Makoto; Miura, Kenta; Satoh, Takahiro; Koka, Masashi; Yamada, Naoto; Kamiya, Tomihiro; Hanaizumi, Osamu

    2016-06-01

    Micrometer-scale responses of radio-photoluminescence (RPL) glass dosimeters to focused ionized particle radiation were evaluated by combining ion-beam-induced luminescence (IBIL) and proton beam writing (PBW) using a 3 MeV focused proton microbeam. RPL phosphate glass dosimeters doped with ionic Ag or Cu activators at concentrations of 0.2 and 0.1% were fabricated, and their scintillation intensities were evaluated by IBIL spectroscopy under a PBW micropatterning condition. Compared with the Ag-doped dosimeter, the Cu-doped dosimeter was more tolerant of the radiation, while the peak intensity of its luminescence was lower, under the precise dose control of the proton microprobe. Proton-irradiated areas were successfully recorded using these dosimeters and their RPL centers were visualized under 375 nm ultraviolet light. The reproduction of the irradiated region by post-RPL imaging suggests that precise estimation of irradiation dose using microdosimeters can be accomplished by optimizing RPL glass dosimeters for various proton microprobe applications in organic material analysis and in micrometer-scale material modifications.

  10. Plasmon-induced enhancement of yellow-red luminescence in InGaN/Au nanocomposites

    SciTech Connect

    Belyaev, K. G. Usikova, A. A.; Jmerik, V. N.; Kop’ev, P. S.; Ivanov, S. V.; Toropov, A. A.; Brunkov, P. N.

    2015-02-15

    A significant (by up to a factor of 7) increase in the internal quantum efficiency of luminescence is achieved at room temperature in semiconductor-metal-insulator hybrid structures fabricated by the successive deposition of gold and Si{sub 3}N{sub 4} over an array of InGaN nanoblocks, grown by molecular-beam epitaxy. The observed effect can be accounted for by the resonant interaction of excitons localized in InGaN nanoblocks with localized surface-plasmon modes in gold intrusions embedded into InGaN and Si{sub 3}N{sub 4}.

  11. Charge trapping induced by plasma in alumina electrode surface investigated by thermoluminescence and optically stimulated luminescence

    SciTech Connect

    Ambrico, P. F.; Ambrico, M.; Schiavulli, L.; Ligonzo, T.; Augelli, V.

    2009-02-02

    The plasma of a dielectric barrier discharge can fill traps in the alumina that cover the electrode. Trap energies and lifetimes are estimated by thermoluminescence and optically stimulated luminescence. Comparison with similar results for traps created by other radiation sources clarifies the mechanisms regulating this effect. Alumina's trap energies are approximately 1 eV, and the traps remain active for several days after plasma exposure. These results could be important to keep dielectric barrier discharge plasmas uniform since a trapped charge can be an electron reservoir.

  12. Zn vacancy induced green luminescence on non-polar surfaces in ZnO nanostructures

    PubMed Central

    Fabbri, F.; Villani, M.; Catellani, A.; Calzolari, A.; Cicero, G.; Calestani, D.; Calestani, G.; Zappettini, A.; Dierre, B.; Sekiguchi, T.; Salviati, G.

    2014-01-01

    Although generally ascribed to the presence of defects, an ultimate assignment of the different contributions to the emission spectrum in terms of surface states and deep levels in ZnO nanostructures is still lacking. In this work we unambiguously give first evidence that zinc vacancies at the (1010) nonpolar surfaces are responsible for the green luminescence of ZnO nanostructures. The result is obtained by performing an exhaustive comparison between spatially resolved cathodoluminescence spectroscopy and imaging and ab initio simulations. Our findings are crucial to control undesired recombinations in nanostructured devices. PMID:24894901

  13. On second harmonic generation and multiphoton-absorption induced luminescence from laser-reshaped silver nanoparticles embedded in glass.

    PubMed

    Zolotovskaya, S A; Tyrk, M A; Stalmashonak, A; Gillespie, W A; Abdolvand, A

    2016-10-28

    Spherical silver nanoparticles (NPs) of 30 nm diameter embedded in soda-lime glass were uniformly reshaped (elongated) after irradiation by a linearly polarised 250 fs pulsed laser operating within the NPs' surface plasmon resonance band. We observed second harmonic generation (SHG) and multiphoton-absorption-induced luminescence (MAIL) in the embedded laser-reshaped NPs upon picosecond (10 ps) pulsed laser excitation at 1064 nm. A complementary study of SHG and MAIL was conducted in soda-lime glass containing embedded, mechanically-reshaped silver NPs of a similar elongation ratio (aspect ratio) to the laser-reshaped NPs. This supports the notion that the observed difference in SHG and MAIL in the studied nanocomposite systems is due to the shape modification mechanism. The discrete dipole approximation method was used to assess the absorption and scattering cross-sections of the reshaped NPs with different elongation ratios.

  14. Efficient light harvesting of a luminescent solar concentrator using excitation energy transfer from an aggregation-induced emitter.

    PubMed

    Banal, James L; Ghiggino, Kenneth P; Wong, Wallace W H

    2014-12-14

    The compromise between light absorption and reabsorption losses limits the potential light conversion efficiency of luminescent solar concentrators (LSCs). Current approaches do not fully address both issues. By using the excitation energy transfer (EET) strategy with a donor chromophore that exhibits aggregation-induced emission (AIE) behaviour, it is shown that both transmission and reabsorption losses can be minimized in a LSC device achieving high light collection and concentration efficiencies. The light harvesting performance of the LSC developed has been characterized using fluorescence quantum yield measurements and Monte Carlo ray tracing simulations. Comparative incident photon conversion efficiency and short-circuit current data based on the LSC coupled to a silicon solar cell provide additional evidence for improved performance.

  15. Ligand Induced Anionic Cuprous Cyanide Framework for Cupric Ion Turn on Luminescence Sensing and Photocatalytic Degradation of Organic Dyes.

    PubMed

    Xu, Xiao-Yan; Chen, Qiu-Cheng; Yu, Ya-Dong; Huang, Xiao-Chun

    2016-01-04

    A new microporous luminescent coordination polymer [(CH3)2NH2]·[Cu2(CN)3] (1) with channels occupied by dimethylamine cations was synthesized due to the inducing effect of 2-(2'-pyridyl)imidazole. Complex 1 exhibits bright-green emission in the solid state, and its emission intensity would be significantly enhanced, especially by DMAc and cupric ion after immersing the as-synthesized crystals of 1 into common organic solvents or methanol solutions of various metal ions. In addition, 1 exhibits photocatalytic activity for the degradation of RhB and MB under natural light and is stable during the photocatalysis process. Thus, 1 can act as a multifunctional material for selectively sensing of Cu(2+) and effectively photocatalytic degradation of dyes.

  16. Ag7+ ion induced modification of morphology, optical and luminescence behaviour of charge compensated CaMoO4 nanophosphor

    NASA Astrophysics Data System (ADS)

    Dutta, S.; Som, S.; Kunti, A. K.; Sharma, S. K.; Kumar, Vijay; Swart, H. C.; Visser, H. G.

    2016-10-01

    The present paper reports on the swift heavy ion (SHI) induced structural, optical and luminescence properties of CaMoO4:Dy3+/K+ nanophosphor synthesized via hydrothermal route. Herein 100 MeV Ag7+ ion beam was used varying fluence from 1 × 1011 to 1 × 1013 ions/cm2. The depth profile of the Ag7+ ions was estimated using SRIM code. XRD and FESEM results revealed the loss of crystallinity and reduction in particle size after SHI irradiations. The XPS technique confirmed the stability of oxidation states of the elements. Reflectance spectra exhibited a red shift in the absorption band, followed by a decrease in band gap. Decrease in the intensity of the photoluminescence peaks without any change in band positions was also obtained after ion irradiation. The thermoluminescence (TL) characteristics were discussed in detail, and the trapping parameter was calculated. The results were compared on the grounds of linear energy transfer of the irradiated ions.

  17. On second harmonic generation and multiphoton-absorption induced luminescence from laser-reshaped silver nanoparticles embedded in glass

    NASA Astrophysics Data System (ADS)

    Zolotovskaya, S. A.; Tyrk, M. A.; Stalmashonak, A.; Gillespie, W. A.; Abdolvand, A.

    2016-10-01

    Spherical silver nanoparticles (NPs) of 30 nm diameter embedded in soda-lime glass were uniformly reshaped (elongated) after irradiation by a linearly polarised 250 fs pulsed laser operating within the NPs’ surface plasmon resonance band. We observed second harmonic generation (SHG) and multiphoton-absorption-induced luminescence (MAIL) in the embedded laser-reshaped NPs upon picosecond (10 ps) pulsed laser excitation at 1064 nm. A complementary study of SHG and MAIL was conducted in soda-lime glass containing embedded, mechanically-reshaped silver NPs of a similar elongation ratio (aspect ratio) to the laser-reshaped NPs. This supports the notion that the observed difference in SHG and MAIL in the studied nanocomposite systems is due to the shape modification mechanism. The discrete dipole approximation method was used to assess the absorption and scattering cross-sections of the reshaped NPs with different elongation ratios.

  18. Phonon-induced pure-dephasing of luminescence, multiple exciton generation, and fission in silicon clusters

    NASA Astrophysics Data System (ADS)

    Liu, Jin; Neukirch, Amanda J.; Prezhdo, Oleg V.

    2013-10-01

    The size and temperature dependence of the pure-dephasing processes involved in luminescence, multiple exciton generation (MEG), and multiple exciton fission (MEF) are investigated for Sin clusters (n = 5-10, 15) using ab initio molecular dynamics and optical response function theory. The cluster bandgaps correlate with two types of binding energy, indicating that bandgaps can be used to characterize cluster stability. Ranging from 5 to 100 fs, the dephasing times are found to be longest for MEF and shortest for MEG, with luminescence falling in the middle range. Generally, the dephasing is fast, if the orbitals supporting the pair of states involved in the superpositions differ in energy, atomic localization, and number of nodes. The dephasing accelerates with temperature, because more phonon modes are activated, and lower frequency acoustic modes are able to explore the anhamonic part of the potential energy surface. The temperature dependence is stronger for larger clusters, since they possess a wider range of low-frequency anharmonic modes. Our research indicates that rapid dephasing in Si clusters favors generation of independent charge carriers from single and multiple excitons, making the clusters a promising material for photon energy conversion. The simulations of the dephasing processes reported in this work assist in understanding of the exciton evolution pathways in inorganic semiconductor clusters and other nanoscale materials.

  19. Quantum vortices and thermally induced luminescence of nitrogen nanoclusters immersed in liquid helium

    NASA Astrophysics Data System (ADS)

    Meraki, A.; McColgan, P. T.; Rentzepis, P. M.; Li, R. Z.; Lee, D. M.; Khmelenko, V. V.

    2017-03-01

    We performed investigations of ensembles of molecular nitrogen nanoclusters, containing stabilized nitrogen atoms, immersed in liquid helium by electron spin resonance and optical spectroscopy. We observed thermoluminescence of nitrogen atoms and molecules via increasing temperature from 1.25 to 4.4 K. Two thermoluminescence maxima were observed, one in superfluid helium (HeII) at T ˜1.9 K and another in normal helium (HeI) at T ˜3.2 K . We explain appearance of luminescence in HeII by chemical reactions of nitrogen atoms on surfaces of nanoclusters which might be initiated by quantum vortices. Thermoluminescence in HeI occurs due to the process of nanocluster association resulting in thermal explosions of a small fraction of nanoclusters. This research might open new possibilities for studying a broad range of chemical reactions initiated by quantum vortices in HeII.

  20. Bimetallic Au2 Cu6 Nanoclusters: Strong Luminescence Induced by the Aggregation of Copper(I) Complexes with Gold(0) Species.

    PubMed

    Kang, Xi; Wang, Shuxin; Song, Yongbo; Jin, Shan; Sun, Guodong; Yu, Haizhu; Zhu, Manzhou

    2016-03-07

    The concept of aggregation-induced emission (AIE) has been exploited to render non-luminescent Cu(I) SR complexes strongly luminescent. The Cu(I) SR complexes underwent controlled aggregation with Au(0) . Unlike previous AIE methods, our strategy does not require insoluble solutions or cations. X-ray crystallography validated the structure of this highly fluorescent nanocluster: Six thiolated Cu atoms are aggregated by two Au atoms (Au2 Cu6 nanoclusters). The quantum yield of this nanocluster is 11.7 %. DFT calculations imply that the fluorescence originates from ligand (aryl groups on the phosphine) to metal (Cu(I) ) charge transfer (LMCT). Furthermore, the aggregation is affected by the restriction of intramolecular rotation (RIR), and the high rigidity of the outer ligands enhances the fluorescence of the Au2 Cu6 nanoclusters. This study thus presents a novel strategy for enhancing the luminescence of metal nanoclusters (by the aggregation of active metal complexes with inert metal atoms), and also provides fundamental insights into the controllable synthesis of highly luminescent metal nanoclusters.

  1. Novel applications of diagnostic x-rays in activating photo-agents through x-ray induced visible luminescence from rare-earth particles: an in vitro study

    NASA Astrophysics Data System (ADS)

    Abliz, Erkinay; Collins, Joshua E.; Friedberg, Joseph S.; Kumar, Ajith; Bell, Howard; Waynant, Ronald W.; Tata, Darrell B.

    2010-02-01

    Photodynamic agents such as Photofrin II (Photo II) utilized in photodynamic therapy (PDT) possess a remarkable property to become preferentially retained within the tumor's micro-environment. Upon the photo-agent's activation through visible light photon absorption, the agents exert their cellular cytotoxicity through type II and type I mechanistic pathways through extensive generation of reactive oxygen species (ROS): singlet oxygen 1O2, superoxide anion O2 -, and hydrogen peroxide H2O2, within the intratumoral environment. Unfortunately, due to shallow visible light penetration depth (~2mm to 5mm) in tissues, the PDT strategy currently has largely been restricted to the treatments of surface tumors, such as the melanomas. Additional invasive strategies through optical fibers are currently utilized in getting the visible light into the intended deep seated targets within the body for PDT. In this communication, we report on a novel strategy in utilizing "soft" energy diagnostic X-rays to indirectly activate Photo II through X-ray induced luminescence from Gadolinium oxysulfide (20 micron dimension) particles doped with Terbium: Gd2O2S:Tb. X-ray induced visible luminescence from Gd2O2S:Tb particles was spectroscopically characterized and the ROS production levels from clinically relevant concentration (10 μg/ml) of Photo II was quantified through changes in the Vitamin C absorbance. ROS kinetics through X-ray induced luminescence was found to be similar to the ROS kinetics from red He-Ne laser exposures used in the clinics. Taken together, in-vitro findings herein provide the basis for future studies in determining the safety and efficacy of this non-invasive X-ray induced luminescence strategy in activating photo-agent in deep seated tumors.

  2. Luminescent Poly(vinyl alcohol)/Carbon Quantum Dots Composites with Tunable Water-Induced Shape Memory Behavior in Different pH and Temperature Environments.

    PubMed

    Yang, Guanghui; Wan, Xuejuan; Liu, Yijin; Li, Rui; Su, Yikun; Zeng, Xierong; Tang, Jiaoning

    2016-12-21

    Luminescent water-induced shape memory polymer (SMP) composites with tunable shape recovery rate are developed by blending poly(vinyl alcohol) (PVA) and carbon quantum dots (CQDs). The oxygen and active hydrogen-rich CQDs can serve as extra physical cross-linking points in PVA via strong hydrogen bonding interaction, which largely improves the shape memory performances of PVA. At room temperature, water can successfully actuate the shape recovery of deformed PVA/CQDs composite. It is demonstrated that this water-induced shape recovery is mainly attributed to the plasticizing effect of water and its competitive hydrogen bonding. Furthermore, a quantitative bending test suggests that the shape recovery time of this water-induced SMP is tunable by altering the environmental pH value and temperature, and a relatively large shape recovery time window (from 20 to 200 s) can be achieved. In addition, the introduction of CQDs endows the PVA/CQDs SMP composites with excellent luminescent property, which makes the shape change of SMP visible under UV light. It should be noted that the mild stimulus condition and tunable shape recovery performances make the luminescent visible PVA/CQDs SMP feasible for diverse biological applications in smart medical devices, stimuli-responsive drug-release, and intelligent sensors in vivo and in vitro.

  3. X-ray induced luminescence properties of (Y,Eu)AlO3 single crystals

    NASA Astrophysics Data System (ADS)

    Kuro, Tomoaki; Nakauchi, Daisuke; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki

    2017-02-01

    We investigated photoluminescence, scintillation and dosimeter properties of (Y1-x Eux)AlO3 (x = 0.001, 0.5 and 1) single crystals (hereafter denoted as Eu:YAP for x = 0.001, EYAP for x = 0.5 and EAP for x = 1). The samples were prepared by the Floating Zone method. In photoluminescence (PL), we observed a broad emission around 300-400 nm due to host under excitation of 280 nm, and emissions due to the 4f state transitions of Eu3+ appeared around 590 nm and 615 nm. Scintillation spectra also show emission peaks around 590 and 615 nm due to the 4f state transitions of Eu3+ in all the samples. In addition, emissions around 300-400 nm due to YAP host and around 550-700 nm due to 5d-4f transitions of Eu2+ appeared in Eu:YAP. The PL and scintillation decay time profiles consisted of several exponential decay components. The fast (ns) component group was possibly due to host emission, and especially Eu:YAP demonstrated a very fast PL decay time of 16 ns. The intermediate (μs) component group was due to the 5d-4f transitions of Eu2+. The slow (ms) component group was ascribed to the 4f state transitions of Eu3+ ion. The Eu:YAP sample showed intense thermally-stimulated luminescence (TSL) with peaks at 46, 155, 255 and 443 °C. The intensity was much higher than those of EAP and EYAP. In particular, the peak at 254 °C, which showed the highest intensity, was due to doping with Eu. The TSL dose response function showed a good linearity (R2 > 0.99) over a wide dose range from 0.1 mGy to 100 mGy for Eu:YAP, which showed the highest sensitivity among the present samples.

  4. Facile preparation and biological imaging of luminescent polymeric nanoprobes with aggregation-induced emission characteristics through Michael addition reaction.

    PubMed

    Lv, Qiulan; Wang, Ke; Xu, Dazhuang; Liu, Meiying; Wan, Qing; Huang, Hongye; Liang, Shangdong; Zhang, Xiaoyong; Wei, Yen

    2016-09-01

    Water dispersion aggregation-induced emission (AIE) dyes based nanomaterials have recently attracted increasing attention in the biomedical fields because of their unique optical properties, outstanding performance as imaging and therapeutic agents. The methods to conjugate hydrophilic polymers with AIE dyes to solve the hydrophobic nature of AIE dyes and makeS them widely used in biomedicine, which have been extensively explored and paid great effort previously. Although great advance has been made in the fabrication and biomedical applications of AIE-active polymeric nanoprobes, facile and efficient strategies for fabrication of biodegradable AIE-active nanoprobes are still high desirable. In this work, amphiphilic biodegradable fluorescent organic nanoparticles (PLL-TPE-O-E FONs) have been fabricated for the first time by conjugation of AIE dye tetraphenylethene acrylate (TPE-O-E) with Poly-l-Lysine (PLL) through a facile one-step Michael addition reaction, which was carried out under rather mild conditions, included air atmosphere, near room temperature and absent of metal catalysts or hazardous reagents. Due to the unique AIE properties, these amphiphilic copolymers tend to self-assemble into high luminescent water dispersible nanoparticles with size range from 400 to 600nm. Laser scanning microscope and cytotoxicity results revealed that PLL-TPE-O-E FONs can be internalized into cytoplasm with negative cytotoxicity, which implied that PLL-TPE-O-E FONs are promising for biological applications.

  5. Characterising the Geomorphic Response of a Tropical Mega-River to an Extreme, Cyclone Induced, Flood Event.

    NASA Astrophysics Data System (ADS)

    Hackney, C. R.; Leyland, J.; Darby, S. E.; Parsons, D. R.; Aalto, R. E.; Nicholas, A. P.; Best, J.

    2014-12-01

    Extreme events have the ability to induce extensive geomorphic change in fluvial systems as a result of elevated discharge levels, increased sediment transport capacity and associated changes in sheer stresses along channel boundaries. Understanding how rapid rises in water levels change flow structures and channel boundary roughness is key to understanding the relative significance of large events in terms of driving local and system wide geomorphic change. However, capturing the fluvial process dynamics in operation during such events is technically and logistically difficult, especially in the world's largest rivers. During September 2013, on the peak of the monsoon, a series of tropical cyclones induced a large flood event within the Mekong basin. At the peak of the flood wave, discharge measured ~60000 m3/s; the 11th largest flood on record. Pre and post event high resolution topographic surveys of parts of the bed and bank were captured using a combination of contiguous multibeam echo sounding (MBES) and terrestrial laser scanning (TLS) during the event. Simultaneously detailed measurements of cross sectional and near bank flow structure were acquired using an acoustic Doppler current profiler (aDcp). Together, these unique datasets can be used to characterise and assess the geomorphic impact of a cyclone induced extreme flood event on the Mekong. We show how flow structures in the near bank region evolve with stage during the extreme event and how the associated geomorphic response is modulated by the distinctive process dynamics of a mega-river.

  6. Identification and characterisation of human apoptosis inducing proteins using cell-based transfection microarrays and expression analysis

    PubMed Central

    Palmer, Ella L; Miller, Andrew D; Freeman, Tom C

    2006-01-01

    Background Cell-based microarrays were first described by Ziauddin and Sabatini in 2001 as a powerful new approach for performing high throughput screens of gene function. An important application of cell-based microarrays is in screening for proteins that modulate gene networks. To this end, cells are grown over the surface of arrays of RNAi or expression reagents. Cells growing in the immediate vicinity of the arrayed reagents are transfected and the arrays can then be scanned for cells showing localised changes in function. Here we describe the construction of a large-scale microarray using expression plasmids containing human genes, its use in screening for genes that induce apoptosis when over-expressed and the characterisation of a number of these genes by following the transcriptional response of cell cultures during their induction of apoptosis. Results High-density cell-based arrays were successfully fabricated using 1,959 un-tagged open reading frames (ORFs) taken from the Mammalian Gene Collection (MGC) in mammalian expression vectors. The arrays were then used to screen for genes inducing apoptosis in Human Embryonic Kidney (HEK293T) cells. Using this approach, 10 genes were clearly identified and confirmed to induce apoptosis. Some of these genes have previously been linked to apoptosis, others not. The mechanism of action of three of the 10 genes were then characterised further by following the transcriptional events associated with apoptosis induction using expression profiling microarrays. This data demonstrates a clear pro-apoptotic transcriptional response in cells undergoing apoptosis and also suggests the use of common apoptotic pathways regardless of the nature of the over-expressed protein triggering cell death. Conclusion This study reports the design and use of the first truly large-scale cell-based microarrays for over-expression studies. Ten genes were confirmed to induce apoptosis, some of which were not previously known to possess this

  7. Structural and optical effects induced by gamma irradiation on NdPO{sub 4}: X-ray diffraction, spectroscopic and luminescence study

    SciTech Connect

    Sadhasivam, S.; Rajesh, N.P.

    2016-02-15

    Highlights: • Inorganic NdPO{sub 4} crystal was grown first time using potassium polyphosphate (K{sub 6}P{sub 4}O{sub 13}) flux. • NdPO{sub 4} crystal is insoluble in water, non-hygroscopic and high radiation resistance favoring for actinides host. • Actinide immobilization can be made at 1273 K. • High yield of 1061 nm photon emission. - Abstract: Rare earth orthophosphate (NdPO{sub 4}) monazite single crystals were grown using high temperature flux growth method employing K{sub 6}P{sub 4}O{sub 13} (K{sub 6}) as molten solvent. Their structural parameters were studied using single crystal X-ray diffraction (XRD) method. The grown crystals were examined by SEM and EDX techniques for their homogeniousity and inclusion in the crystals. The influence of gamma irradiation in structural and optical absorption properties were studied by the powder XRD, FTIR and reflectance spectroscopy. The effect of gamma irradiation on luminescence properties was recorded. No significant structural change is observed up to 150 kGy gamma dose. The gamma ray induced charge trap in the crystal was saturated to 40 kGy dose. The luminescence intensity decreases with an increase in the irradiation. The emission of luminescence intensity stabilizes above 40 kGy gamma dose.

  8. Near-IR luminescence and field-induced single molecule magnet of four salen-type ytterbium complexes.

    PubMed

    Liu, Tian-Qi; Yan, Peng-Fei; Luan, Fang; Li, Yu-Xin; Sun, Jing-Wen; Chen, Chuan; Yang, Fan; Chen, Han; Zou, Xiao-Yan; Li, Guang-Ming

    2015-01-05

    A series of rigid hexadentate salen-type (H2L) ytterbium complexes, namely, [Yb2L3(CH3OH)]·3CH3CN (1), [Yb2LL'L″(CH3OH)(H2O)2](ClO4)2·CH3OH·H2O (2), [Yb2L(OAc)4(CH3OH)2]·2CH3OH (3), and {[Yb2L(OAc)4]·3H2O}n (4) (H2L = N,N'-bis(2-oxy-3-methoxybenzylidene)-1,2-phenylenediamine, HL' = 2-(2'-hydroxy-3'-methyloxy-phenyl)benzimidazole and HL" = 3-methoxysalicylaldehyde) have been synthesized by reactions of H2L with multifarious Yb(3+) salts. X-ray crystallographic analyses demonstrate that complex 1 is of a triple-decker sandwich-type Yb2L3 structure with a ratio of H2L/Yb = 3:2, 2 and 3 possess the unique Yb2 core with a ratio of H2L/Yb = 2:2 and 1:2, respectively, 4 exhibits one dimensional coordination polymers in which the polymeric structures are formed by acetate (OAc(-)) groups. All complexes 1-4 exhibit near-IR luminescence, which can be rationalized on the basis of the disparate structural effects. The magnetic analysis unveils that all complexes 1-4 are of field-induced single-molecule magnet behavior with the energy barriers (Ueff/kB) of 14.5, 2.0, 9.5, and 2.4 K at 3 kOe direct current fields, respectively.

  9. Ion beam induced charge characterisation of a silicon microdosimeter using a heavy ion microprobe

    NASA Astrophysics Data System (ADS)

    Cornelius, Iwan; Siegele, Rainer; Rosenfeld, Anatoly B.; Cohen, David D.

    2002-05-01

    An ion beam induced charge (IBIC) facility has been added to the existing capabilities of the ANSTO heavy ion microprobe and the results of the first measurements are presented. Silicon on insulator (SOI) diode arrays with microscopic junction sizes have recently been proposed as microdosimeters for hadron therapy. A 20 MeV carbon beam was used to perform IBIC imaging of a 10 μm thick SOI device.

  10. Characterisation of Immune and Neuroinflammatory Changes Associated with Chemotherapy-Induced Peripheral Neuropathy.

    PubMed

    Makker, Preet G S; Duffy, Samuel S; Lees, Justin G; Perera, Chamini J; Tonkin, Ryan S; Butovsky, Oleg; Park, Susanna B; Goldstein, David; Moalem-Taylor, Gila

    2017-01-01

    Chemotherapy-induced peripheral neuropathy (CIPN) and associated neuropathic pain is a debilitating adverse effect of cancer treatment. Current understanding of the mechanisms underpinning CIPN is limited and there are no effective treatment strategies. In this study, we treated male C57BL/6J mice with 4 cycles of either Paclitaxel (PTX) or Oxaliplatin (OXA) over a week and tested pain hypersensitivity and changes in peripheral immune responses and neuroinflammation on days 7 and 13 post 1st injection. We found that both PTX and OXA caused significant mechanical allodynia. In the periphery, PTX and OXA significantly increased circulating CD4+ and CD8+ T-cell populations. OXA caused a significant increase in the percentage of interleukin-4+ lymphocytes in the spleen and significant down-regulation of regulatory T (T-reg) cells in the inguinal lymph nodes. However, conditional depletion of T-reg cells in OXA-treated transgenic DEREG mice had no additional effect on pain sensitivity. Furthermore, there was no leukocyte infiltration into the nervous system of OXA- or PTX-treated mice. In the peripheral nervous system, PTX induced expression of the neuronal injury marker activating transcription factor-3 in IB4+ and NF200+ sensory neurons as well as an increase in the chemokines CCL2 and CCL3 in the lumbar dorsal root ganglion. In the central nervous system, PTX induced significant astrocyte activation in the spinal cord dorsal horn, and both PTX and OXA caused reduction of P2ry12+ homeostatic microglia, with no measurable changes in IBA-1+ microglia/macrophages in the dorsal and ventral horns. We also found that PTX induced up-regulation of several inflammatory cytokines and chemokines (TNF-α, IFN-γ, CCL11, CCL4, CCL3, IL-12p70 and GM-CSF) in the spinal cord. Overall, these findings suggest that PTX and OXA cause distinct pathological changes in the periphery and nervous system, which may contribute to chemotherapy-induced neuropathic pain.

  11. Characterisation of Immune and Neuroinflammatory Changes Associated with Chemotherapy-Induced Peripheral Neuropathy

    PubMed Central

    Makker, Preet G. S.; Duffy, Samuel S.; Lees, Justin G.; Perera, Chamini J.; Tonkin, Ryan S.; Butovsky, Oleg; Park, Susanna B.; Goldstein, David

    2017-01-01

    Chemotherapy-induced peripheral neuropathy (CIPN) and associated neuropathic pain is a debilitating adverse effect of cancer treatment. Current understanding of the mechanisms underpinning CIPN is limited and there are no effective treatment strategies. In this study, we treated male C57BL/6J mice with 4 cycles of either Paclitaxel (PTX) or Oxaliplatin (OXA) over a week and tested pain hypersensitivity and changes in peripheral immune responses and neuroinflammation on days 7 and 13 post 1st injection. We found that both PTX and OXA caused significant mechanical allodynia. In the periphery, PTX and OXA significantly increased circulating CD4+ and CD8+ T-cell populations. OXA caused a significant increase in the percentage of interleukin-4+ lymphocytes in the spleen and significant down-regulation of regulatory T (T-reg) cells in the inguinal lymph nodes. However, conditional depletion of T-reg cells in OXA-treated transgenic DEREG mice had no additional effect on pain sensitivity. Furthermore, there was no leukocyte infiltration into the nervous system of OXA- or PTX-treated mice. In the peripheral nervous system, PTX induced expression of the neuronal injury marker activating transcription factor-3 in IB4+ and NF200+ sensory neurons as well as an increase in the chemokines CCL2 and CCL3 in the lumbar dorsal root ganglion. In the central nervous system, PTX induced significant astrocyte activation in the spinal cord dorsal horn, and both PTX and OXA caused reduction of P2ry12+ homeostatic microglia, with no measurable changes in IBA-1+ microglia/macrophages in the dorsal and ventral horns. We also found that PTX induced up-regulation of several inflammatory cytokines and chemokines (TNF-α, IFN-γ, CCL11, CCL4, CCL3, IL-12p70 and GM-CSF) in the spinal cord. Overall, these findings suggest that PTX and OXA cause distinct pathological changes in the periphery and nervous system, which may contribute to chemotherapy-induced neuropathic pain. PMID:28125674

  12. Luminescent probe in the study of surfactant-induced structural changes in serum albumin in human blood plasma

    NASA Astrophysics Data System (ADS)

    Melnikov, A. G.; Pravdin, A. B.; Kochubey, V. I.; Melnikov, G. V.

    2005-06-01

    The luminescence-kinetic technique of the monitoring of structural changes in albumins of human blood plasma that uses a luminescent probe-eosin is proposed. Phosphorescence of eosin bound to the globular proteins of blood plasma-albumins was recorded at room temperature. It is found that under the action of sodium dodecylsulfate on the albumins the rate constant of eosin phosphorescence decay grows and the intensity of eosin phosphorescence decreases. It is assumed that these changes are connected with the denaturing of blood plasma albumins by sodium dodecylsulfate.

  13. Pharmacological characterisation of capsaicin-induced relaxations in human and porcine isolated arteries

    PubMed Central

    Gupta, Saurabh; Lozano-Cuenca, Jair; Villalón, Carlos M.; de Vries, René; Garrelds, Ingrid M.; Avezaat, Cees J. J.; van Kats, Jorge P.; Saxena, Pramod R.

    2007-01-01

    Capsaicin, a pungent constituent from red chilli peppers, activates sensory nerve fibres via transient receptor potential vanilloid receptors type 1 (TRPV1) to release neuropeptides like calcitonin gene-related peptide (CGRP) and substance P. Capsaicin-sensitive nerves are widely distributed in human and porcine vasculature. In this study, we examined the mechanism of capsaicin-induced relaxations, with special emphasis on the role of CGRP, using various pharmacological tools. Segments of human and porcine proximal and distal coronary arteries, as well as cranial arteries, were mounted in organ baths. Concentration response curves to capsaicin were constructed in the absence or presence of the CGRP receptor antagonist olcegepant (BIBN4096BS, 1 μM), the neurokinin NK1 receptor antagonist L-733060 (0.5 μM), the voltage-sensitive calcium channel blocker ruthenium red (100 μM), the TRPV1 receptor antagonist capsazepine (5 μM), the nitric oxide synthetase inhibitor Nω-nitro-l-arginine methyl ester HCl (l-NAME; 100 μM), the gap junction blocker 18α-glycyrrhetinic acid (10 μM), as well as the RhoA kinase inhibitor Y-27632 (1 μM). Further, we also used the K+ channel inhibitors 4-aminopyridine (1 mM), charybdotoxin (0.5 μM) + apamin (0.1 μM) and iberiotoxin (0.5 μM) + apamin (0.1 μM). The role of the endothelium was assessed by endothelial denudation in distal coronary artery segments. In distal coronary artery segments, we also measured levels of cyclic adenosine monophosphate (cAMP) after exposure to capsaicin, and in human segments, we also assessed the amount of CGRP released in the organ bath fluid after exposure to capsaicin. Capsaicin evoked concentration-dependent relaxant responses in precontracted arteries, but none of the above-mentioned inhibitors did affect these relaxations. There was no increase in the cAMP levels after exposure to capsaicin, unlike after (exogenously administered) α-CGRP. Interestingly, there were

  14. Structural characterisation of algae Costaria costata fucoidan and its effects on CCl₄-induced liver injury.

    PubMed

    Wang, Qiukuan; Song, Yuefan; He, Yunhai; Ren, Dandan; Kow, Felicia; Qiao, Zhiyong; Liu, Shu; Yu, Xingju

    2014-07-17

    Fucoidan is a well-known natural product that is commonly found in brown algae and shows a variety of activities, including immunomodulation, antioxidation, and the combat of carcinogens. The fucoidan fractions of Costaria costata, a brown algae introduced from Japan and cultured in northern China, were studied. The fucoidan fractions were extracted, separated, and purified using a combinatorial procedure consisting of enzymolysis, ethanol precipitation, and DEAE and size-exclusion chromatographies. The fundamental characteristics of the four enriched fucoidan fractions (F1-F4), such as their sulphate content and monosaccharide composition, were investigated. FTIR and NMR spectroscopy were employed to further elucidate the structural features of the four fractions. It was found that the F1-F4 fractions all showed oxidative activity against hydroxyl radicals. The bioactive effects of the fucoidan fractions on CCl4-induced liver injury suggest their potential use as ingredients for functional foods or pharmaceuticals.

  15. Heat induced transformation of fossil mastodon ivory into turquoise 'odontolite'. Structural and elemental characterisation

    NASA Astrophysics Data System (ADS)

    Reiche, I.; Vignaud, C.; Menu, M.

    2000-10-01

    The present work deals with the structural and elemental analysis of turquoise mineral imitations as 'odontolite' or bone turquoise by transmission electron microscopy (TEM), scanning electron microscopy (SEM-EDX) and particle induced X-ray and γ-ray emission (PIXE-PIGE). The aim of the work is to evidence the former deliberate transformation of fossilised ivory by man in order to transform them into semi-precious stones. We show that the crystal structure of 'odontolite' artefacts consisting of fluorapatite (Ca 5(PO 4) 3F) corresponds to that of heated fossil mastodon ivory (12-15 million years old). Metallic traces detected by PIXE-PIGE in these 'odontolites' are discussed in order to explain their role for coloration. Other more greenish turquoise imitations have a bone-like structure and composition, and carbonate-hydroxylapatite. The presence of copper salts at the surface is responsible for their green coloration.

  16. Molecular Characterisation, Evolution and Expression of Hypoxia-Inducible Factor in Aurelia sp.1

    PubMed Central

    Wang, Guoshan; Yu, Zhigang; Zhen, Yu; Mi, Tiezhu; Shi, Yan; Wang, Jianyan; Wang, Minxiao; Sun, Song

    2014-01-01

    The maintenance of physiological oxygen homeostasis is mediated by hypoxia-inducible factor (HIF), a key transcriptional factor of the PHD-HIF system in all metazoans. However, the molecular evolutionary origin of this central physiological regulatory system is not well characterized. As the earliest eumetazoans, Cnidarians can be served as an interesting model for exploring the HIF system from an evolutionary perspective. We identified the complete cDNA sequence of HIF-1α (ASHIF) from the Aurelia sp.1, and the predicted HIF-1α protein (pASHIF) was comprised of 674 amino acids originating from 2,025 bp nucleotides. A Pairwise comparison revealed that pASHIF not only possessed conserved basic helix-loop-helix (bHLH) and Per-Arnt-Sim (PAS) domains but also contained the oxygen dependent degradation (ODD) and the C-terminal transactivation domains (C-TAD), the key domains for hypoxia regulation. As indicated by sequence analysis, the ASHIF gene contains 8 exons interrupted by 7 introns. Western blot analysis indicated that pASHIF that existed in the polyps and medusa of Aurelia. sp.1 was more stable for a hypoxic response than normoxia. PMID:24926666

  17. Characterisation of TiO 2 deposited by photo-induced chemical vapour deposition

    NASA Astrophysics Data System (ADS)

    Kaliwoh, Never; Zhang, Jun-Ying; Boyd, Ian W.

    2002-01-01

    We report the deposition of thin TiO 2 films on crystalline Si and quartz by photo-induced chemical vapour deposition (CVD) using UV excimer lamps employing a dielectric barrier discharge in krypton chloride (KrCl ∗) to provide intense narrow band radiation at λ=222 nm. The precursor used was titanium isopropoxide (TTIP). Films from around 20-510 nm in thickness with refractive indices from 2.20 to 2.54 were grown at temperatures between 50 and 350 °C. The higher refractive index values compare favourably with the value of 2.58 recorded for the bulk material. The measured deposition rate was around 50 nm/min at 350 °C. Fourier transform infrared spectroscopy (FTIR) revealed the presence of TiO 2 through the observation of a Ti-O absorption peak and the absence of OH in films deposited at 250-350 °C indicated relatively good quality films. The phase of films deposited at 200-350 °C was anatase as determined by X-ray diffraction.

  18. Characterisation of stochastically-induced climate jumps to other histories paced by the astronomical forcing.

    NASA Astrophysics Data System (ADS)

    De Saedeleer, B.

    2012-04-01

    The mystery of ice ages induced by a varying incoming solar radiation has drawn ceaseless attention for several decades. A pleiad of paleoclimatic models has been developed in order to have a try at catching the underlying climate dynamics, and their validity is challenged by comparison with typical milestones in paleoclimatic records. In several published works, the astronomical forcing synchronises the climate to a unique climatic attracting trajectory representing the ice volume evolution. Other studies, though, reported multistability, i.e. the fact that several climatic attracting trajectories could coexist for some given set of parameters, in a deterministic framework. More importantly, it has been illustrated that additional disturbances may cause some 'jumps' from one trajectory to other ones in the climatic history over the last millions years of the Pleistocene. These stochastic effects hence indirectly affect the timing of the glacial inceptions and terminations. The jumping mechanism is closely linked to the widely spread hypothesis that the glacial-interglacial cycles could be primarily triggered by random internal climate variability. A conjecture has recently been made that these externally triggered jumps are the most likely when the temporary desynchronisation (positive largest local Lyapunov exponent) due to the loss of local stability coalesces with the weakening of the global stability due to the proximity to the basin boundary. No proof of this conjecture has however been provided sofar; it is precisely the aim of the present research to assess the conditions for such a jump to occur. We uncover the details of the underlying mechanisms by providing a systematic numerical study of the conditions under which these jumps are likely to occur. Extensive Monte Carlo experiments are performed in order to show that the jumps occur preferentially at specific times or locations in the phase space, for a given level of noise. We show how the most critical

  19. Condensation and salt-induced decondensation of DNA upon incorporation of a V-shaped luminescent [Ru2(bpy)4(mbpibH2)](4+).

    PubMed

    Gan, Gui-Lian; Chao, Hui; Cai, Xue-Ping; Jiang, Zhen-Shen; Li, Hong

    2013-12-01

    This paper first reports on the condensation of DNA to a tightly packed state induced by a V-shaped di-ruthenium(II) complex [Ru2(bpy)4(mbpibH2)]Cl4 (bpy=2,2'-bipyridine and mbpibH2=1,3-bis([1,10]phenanthroline[5,6-d]imidazol-2-yl)benzene), which binds to the groove of herring sperm DNA (hsDNA) with the binding constant of 2.0×10(7)M(-1) (0.05M NaCl, pH7.2). The di-Ru(II) complex is found to induce the condensation of both hsDNA to long chain-like particle clusters and originally circular plasmid pBR322 DNA to particulate structure under neutral conditions. More interestingly, the presence of NaCl has a significant impact on the condensation and decondensation of DNA upon incorporation of [Ru2(bpy)4(mbpibH2)](4+), representing tunable luminescence characteristics by NaCl. High salt concentration facilitates the decondensation of DNA-[Ru2(bpy)4(mbpibH2)](4+) adducts. The results from this study offer an effective method to control the condensation and decondensation of DNA upon incorporation of luminescent concentrators.

  20. Strong thermo-induced single and two-photon green luminescence in self-organized peptide microtubes.

    PubMed

    Semin, S; van Etteger, A; Cattaneo, L; Amdursky, N; Kulyuk, L; Lavrov, S; Sigov, A; Mishina, E; Rosenman, G; Rasing, Th

    2015-03-01

    Diphenylalanine peptide nano- and microtubes formed by self-assembly demonstrate strongly enhanced and tunable single-photon and two-photon luminescence in the visible range, which appears after heat- or laser treatment of these self-organized peptide microtubes. This process significantly extends the functionality of these microstructures and can trigger a new interest in the optical properties of structures based on short peptides.

  1. Piezochromic luminescence behaviors of two new benzothiazole-enamido boron difluoride complexes: intra- and inter-molecular effects induced by hydrostatic compression.

    PubMed

    Wang, Xiaoqing; Liu, Qingsong; Yan, Hui; Liu, Zhipeng; Yao, Mingguang; Zhang, Qingfu; Gong, Shuwen; He, Weijiang

    2015-05-01

    Two new propeller-shaped benzothiazole-enamide boron difluoride complexes exhibiting piezochromic luminescence upon mechanical grinding or hydrostatic compression were prepared. The two analogues displayed the red shift in luminescence under high pressure, while compound 2 with ICT effects showed a more sensitive piezochromic response at low pressure (<1.5 GPa). The different piezochromic luminescence behaviors of these compounds were investigated.

  2. Specific chiral sensing of amino acids using induced circularly polarized luminescence of bis(diimine)dicarboxylic acid europium(III) complexes.

    PubMed

    Okutani, Kazuhiro; Nozaki, Koichi; Iwamura, Munetaka

    2014-06-02

    The circularly polarized luminescence (CPL) from [Eu(pda)2](-) (pda = 1,10-phenanthroline-2,9-dicarboxylic acid) and [Eu(bda)2](-) (bda = 2,2'-bipyridine-6,6'-dicarboxylic acid) in aqueous solutions containing various amino acids was investigated. The europium(III) complexes exhibited bright-red luminescence assignable to the f-f transition of the Eu(III) ion when irradiated with UV light. Although the luminescence was not circularly polarized in the solid state or in aqueous solutions, in accordance with the achiral crystal structure, the complexes exhibited detectable induced CPL (iCPL) in aqueous solutions containing chiral amino acids. In the presence of L-pyrrolidonecarboxylic acid, both [Eu(pda)2](-) and [Eu(bda)2](-) showed similar iCPL intensity (glum ∼ 0.03 for the (5)D0 → (7)F1 transition at 1 mol·dm(-3) of the amino acid). On the other hand, in the presence of L-histidine or L-arginine, [Eu(pda)2](-) exhibited intense CPL (glum ∼ 0.08 for the (5)D0 → (7)F1 transition at 0.10 mol·dm(-3) of the amino acid), whereas quite weak CPL was observed for [Eu(bda)2](-) under the same conditions (glum < 0.01). On the basis of analysis of the iCPL intensities in the presence of 12 amino acids, [Eu(pda)2](-) was found to be a good chiral CPL probe with high sensitivity (about 10(-2) mol·dm(-3)) and high selectivity for L-histidine at pH 3 and for L-arginine at pH 7. The mechanism of iCPL was evaluated by analysis of the fine structures in the luminescence spectra and the amino acid concentration dependence of glum. For the [Eu(pda)2](-)-histidine/arginine systems, the europium(III) complexes possess coordination structures similar to that in the crystal with slight distortion to form a chiral structure due to specific interaction with two zwitterionic amino acids. This mechanism was in stark contrast to that of the europium(III) complex-pyrrolidonecarboxylic acid system in which one amino acid coordinates to the Eu(III) ion to yield an achiral coordination

  3. Limitations and design considerations for donor-acceptor systems in luminescent solar concentrators: the effect of coupling-induced red-edge absorption

    NASA Astrophysics Data System (ADS)

    MacQueen, Rowan W.; Tayebjee, Murad J. Y.; Webb, James E. A.; Falber, Alexander; Thordarson, Pall; Schmidt, Timothy W.

    2016-06-01

    Luminescent solar concentrators (LSCs) use luminescence and waveguiding to concentrate photons within thin dielectric slabs for use in photovoltaic, lighting, and photobioreactor applications. Donor-acceptor systems of organic chromophores are widely used in LSCs to broaden the sunlight absorption range and attempt to reduce loss-inducing reabsorption by the emitting chromophore. We use raytrace simulations across a large parameter space to model the performance of LSCs containing two novel donor-acceptor trimers based on the perylene moiety. We find that under certain conditions, trimers outperform single-dye LSCs as expected. However, at higher concentrations, a slight increase in red-edge absorption by the trimers increases reabsorption and has a deleterious effect on LSC performance. This underscores the large effect that even small changes in the red edge can have, and may discourage the use of donor-acceptor schemes with high interchromophore coupling that promotes red-edge absorption. Finally, we show that for a LSC-PV pair, selecting a PV cell that is well-matched with the LSC emission spectrum has a large effect on the flux gain of the system, and that the systems studied here are well-matched to emerging PV technologies.

  4. The influence of radiation-induced defects on thermoluminescence and optically stimulated luminescence of α-Al2O3:C

    NASA Astrophysics Data System (ADS)

    Nyirenda, A. N.; Chithambo, M. L.

    2017-04-01

    It is known that when α-Al2O3:C is exposed to excessive amounts of ionising radiation, defects are induced within its matrix. We report the influence of radiation-induced defects on the thermoluminescence (TL) and optically stimulated luminescence (OSL) measured from α-Al2O3:C after irradiation to 1000 Gy. These radiation-induced defects are thermally unstable in the region 450-650 °C and result in TL peaks in this range when the TL is measured at 1 °C/s. Heating a sample to 700 °C obliterates the radiation-induced defects, that is, the TL peaks corresponding to the radiation induced defects are no longer observed in the subsequent TL measurements when moderate irradiation doses below 10 Gy are used. The charge traps associated with these radiation-induced defects are more stable than the dosimetric trap when the sample is exposed to either sunlight or 470-nm blue light from LEDs. TL glow curves measured following the defect-inducing irradiation produce a dosimetric peak that is broader and positioned at a higher temperature than observed in glow curves obtained before the heavy irradiation. In addition, sample sensitization/desensitization occurs due to the presence of these radiation-induced defects. Furthermore, both the activation energy and the kinetic order of the dosimetric peak evaluated when the radiation-induced defects are present in the sample are significantly lower in value than those obtained when these defects are absent. The radiation-induced defects also affect the shape and total light sum of the OSL signal as well as the position and width of the resultant residual phototransferred thermoluminescence main peak.

  5. Coherent detection of THz waves based on THz-induced time-resolved luminescence quenching in bulk gallium arsenide.

    PubMed

    Chu, Zheng; Liu, Jinsong; Wang, Kejia

    2012-05-01

    A kind of photoluminescence quenching, in which the time-resolved photoluminescence is modulated by a THz pulse, has been theoretically investigated by performing the ensemble Monte Carlo method in bulk gallium arsenide (GaAs) at room temperature. The quenching ratio could reach up to 50% under a strong THz field (100  kV/cm). The range in which luminescence quenching is linearly proportional to the THz field could be over 60  kV/cm. On the basis of these results, a principle for THz modulation and coherent detection is proposed.

  6. Features of laser-induced luminescence and photoconductivity of layered Cu3In5S9 crystals

    NASA Astrophysics Data System (ADS)

    Guseinov, A. G.; Kyazym-zade, A. G.; Salmanov, V. M.; Mamedov, R. M.; Salmanova, A. A.; Gasanova, L. G.; Mahammadov, A. Z.

    2016-12-01

    Luminescence and photoconductivity of layered Cu3In5S9 crystals at high levels of optical excitation are studied experimentally. A pulsed nanosecond Nd:YAG laser with built-in second and third harmonic generators to generate 1064-, 532-, and 355-nm radiation is used as a light source. It is found that the photoluminescence spectra exhibit two emission bands due to zone-acceptor level and impurity donor-impurity acceptor transitions. It is shown that the photoconductivity in Cu3In5S9 is monopolar. The waveform of the photoconductivity consists of fast and slow components associated with two channels of recombination.

  7. Luminescence induced by dehydration of kaolin - Association with electron-spin-active centers and with surface activity for dehydration-polymerization of glycine

    NASA Technical Reports Server (NTRS)

    Coyne, L.; Hovatter, W.; Sweeney, M.

    1983-01-01

    Experimental data concerning emission of light upon dehydration as a function of preheating and pre-gamma-irradiation are correlated with reported studies of electron-spin resonance (ESR) activity after similar pretreatments. The effect of these pretreatments on the kaolin-promoted incorporation of glycine into peptide oligomers in a wet/cold, hot/dry fluctuating environment is compared to their effect on the ESR and luminescent signals. The existence of spectroscopically active centers appears to be loosely anticorrelated with reaction yield; these yields are increased by increasing the overall energy content of the material. It is concluded that some part of the chemical yield is produced by a mechanism involving intrinsic, excited electronic states of the clay crystal lattice. These states may be derived from thermally, interfacially, and/or mechanically induced charge reorganization within interspersed energy levels in the band structure of the material.

  8. A luminescent nisin biosensor

    NASA Astrophysics Data System (ADS)

    Immonen, Nina; Karp, Matti

    2006-02-01

    Nisin is a lantibiotic, an antibacterial peptide produced by certain Lactococcus lactis strains that kills or inhibits the growth of other bacteria. Nisin is widely used as a food preservative, and its long-time use suggests that it can be generally regarded as safe. We have developed a method for determining the amount of nisin in food samples that is based on luminescent biosensor bacteria. Bacterial luciferase operon luxABCDE was inserted into plasmid pNZ8048, and the construct was transformed by electroporation into Lc. lactis strain NZ9800, whose ability to produce nisin has been erased by deletion of the gene nisA. The operon luxABCDE has been modified to be functional in gram-positive bacteria to confer a bioluminescent phenotype without the requirement of adding an exogenous substrate. In the plasmid pNZ8048, the operon was placed under control of the nisin-inducible nisA promoter. The chromosomal nisRK genes of Lc. lactis NZ9800 allow it to sense nisin in the environment and relay this signal via signal transduction proteins NisK and NisR to initiate transcription from nisA promoter. In the case of our sensor bacteria, this leads to production of luciferase and, thus, luminescence that can be directly measured from living bacteria. Luminescence can be detected as early as within minutes of induction. The nisin assay described here provides a detection limit in the sub-picogram level per ml, and a linear area between 1 - 1000 pg/ml. The sensitivity of this assay exceeds the performance of all previously published methods.

  9. Screening for wound-induced oxylipins in Arabidopsis thaliana by differential HPLC-APCI/MS profiling of crude leaf extracts and subsequent characterisation by capillary-scale NMR.

    PubMed

    Thiocone, Aly; Farmer, Edward E; Wolfender, Jean-Luc

    2008-01-01

    A simple non-targeted differential HPLC-APCI/MS approach has been developed in order to survey metabolome modifications that occur in the leaves of Arabidopsis thaliana following wound-induced stress. The wound-induced accumulation of metabolites, particularly oxylipins, was evaluated by HPLC-MS analysis of crude leaf extracts. A generic, rapid and reproducible pressure liquid extraction procedure was developed for the analysis of restricted leaf samples without the need for specific sample preparation. The presence of various oxylipins was determined by head-to-head comparison of the HPLC-MS data, filtered with a component detection algorithm, and automatically compared with the aid of software searching for small differences in similar HPLC-MS profiles. Repeatability was verified in several specimens belonging to different series. Wound-inducible jasmonates were efficiently highlighted by this non-targeted approach without the need for complex sample preparation as is the case for the 'oxylipin signature' procedure based on GC-MS. Furthermore this HPLC-MS screening technique allowed the isolation of induced compounds for further characterisation by capillary-scale NMR (CapNMR) after HPLC scale-up. In this paper, the screening method is described and applied to illustrate its potential for monitoring polar and non-polar stress-induced constituents as well as its use in combination with CapNMR for the structural assignment of wound-induced compounds of interest.

  10. Photon Luminescence of the Moon

    NASA Technical Reports Server (NTRS)

    Wilson, T.L.; Lee, K.T.

    2009-01-01

    Luminescence is typically described as light emitted by objects at low temperatures, induced by chemical reactions, electrical energy, atomic interactions, or acoustical and mechanical stress. An example is photoluminescence created when photons (electromagnetic radiation) strike a substance and are absorbed, resulting in the emission of a resonant fluorescent or phosphorescent albedo. In planetary science, there exists X-ray fluorescence induced by sunlight absorbed by a regolith a property used to measure some of the chemical composition of the Moon s surface during the Apollo program. However, there exists an equally important phenomenon in planetary science which will be designated here as photon luminescence. It is not conventional photoluminescence because the incoming radiation that strikes the planetary surface is not photons but rather cosmic rays (CRs). Nevertheless, the result is the same: the generation of a photon albedo. In particular, Galactic CRs (GCRs) and solar energetic particles (SEPs) both induce a photon albedo that radiates from the surface of the Moon. Other particle albedos are generated as well, most of which are hazardous (e.g. neutrons). The photon luminescence or albedo of the lunar surface induced by GCRs and SEPs will be derived here, demonstrating that the Moon literally glows in the dark (when there is no sunlight or Earthshine). This extends earlier work on the same subject [1-4]. A side-by-side comparison of these two albedos and related mitigation measures will also be discussed.

  11. Photosensitizer fluorescence and singlet oxygen luminescence as dosimetric predictors of topical 5-aminolevulinic acid photodynamic therapy induced clinical erythema.

    PubMed

    Mallidi, Srivalleesha; Anbil, Sriram; Lee, Seonkyung; Manstein, Dieter; Elrington, Stefan; Kositratna, Garuna; Schoenfeld, David; Pogue, Brian; Davis, Steven J; Hasan, Tayyaba

    2014-02-01

    The need for patient-specific photodynamic therapy (PDT) in dermatologic and oncologic applications has triggered several studies that explore the utility of surrogate parameters as predictive reporters of treatment outcome. Although photosensitizer (PS) fluorescence, a widely used parameter, can be viewed as emission from several fluorescent states of the PS (e.g., minimally aggregated and monomeric), we suggest that singlet oxygen luminescence (SOL) indicates only the active PS component responsible for the PDT. Here, the ability of discrete PS fluorescence-based metrics (absolute and percent PS photobleaching and PS re-accumulation post-PDT) to predict the clinical phototoxic response (erythema) resulting from 5-aminolevulinic acid PDT was compared with discrete SOL (DSOL)-based metrics (DSOL counts pre-PDT and change in DSOL counts pre/post-PDT) in healthy human skin. Receiver operating characteristic curve (ROC) analyses demonstrated that absolute fluorescence photobleaching metric (AFPM) exhibited the highest area under the curve (AUC) of all tested parameters, including DSOL based metrics. The combination of dose-metrics did not yield better AUC than AFPM alone. Although sophisticated real-time SOL measurements may improve the clinical utility of SOL-based dosimetry, discrete PS fluorescence-based metrics are easy to implement, and our results suggest that AFPM may sufficiently predict the PDT outcomes and identify treatment nonresponders with high specificity in clinical contexts.

  12. Photosensitizer fluorescence and singlet oxygen luminescence as dosimetric predictors of topical 5-aminolevulinic acid photodynamic therapy induced clinical erythema

    PubMed Central

    Mallidi, Srivalleesha; Anbil, Sriram; Lee, Seonkyung; Manstein, Dieter; Elrington, Stefan; Kositratna, Garuna; Schoenfeld, David; Pogue, Brian; Davis, Steven J.; Hasan, Tayyaba

    2014-01-01

    Abstract. The need for patient-specific photodynamic therapy (PDT) in dermatologic and oncologic applications has triggered several studies that explore the utility of surrogate parameters as predictive reporters of treatment outcome. Although photosensitizer (PS) fluorescence, a widely used parameter, can be viewed as emission from several fluorescent states of the PS (e.g., minimally aggregated and monomeric), we suggest that singlet oxygen luminescence (SOL) indicates only the active PS component responsible for the PDT. Here, the ability of discrete PS fluorescence-based metrics (absolute and percent PS photobleaching and PS re-accumulation post-PDT) to predict the clinical phototoxic response (erythema) resulting from 5-aminolevulinic acid PDT was compared with discrete SOL (DSOL)-based metrics (DSOL counts pre-PDT and change in DSOL counts pre/post-PDT) in healthy human skin. Receiver operating characteristic curve (ROC) analyses demonstrated that absolute fluorescence photobleaching metric (AFPM) exhibited the highest area under the curve (AUC) of all tested parameters, including DSOL based metrics. The combination of dose-metrics did not yield better AUC than AFPM alone. Although sophisticated real-time SOL measurements may improve the clinical utility of SOL-based dosimetry, discrete PS fluorescence-based metrics are easy to implement, and our results suggest that AFPM may sufficiently predict the PDT outcomes and identify treatment nonresponders with high specificity in clinical contexts. PMID:24503639

  13. Electron beam induced green luminescence and degradation study of CaS:Ce nanocrystalline phosphors for FED applications

    NASA Astrophysics Data System (ADS)

    Kumar, Vinay; Mishra, Varun; Biggs, M. M.; Nagpure, I. M.; Ntwaeaborwa, O. M.; Terblans, J. J.; Swart, H. C.

    2010-01-01

    Green luminescence and degradation of Ce 3+ doped CaS nanocrystalline phosphors were studied with a 2 keV, 10 μA electron beam in an O 2 environment. The nanophosphors were synthesized by the co-precipitation method. The samples were characterized using X-ray diffraction, Transmission electron microscopy, Scanning electron microscopy/electron dispersive X-ray spectroscopy and Photoluminescence (PL) spectroscopy. Cubic CaS with an average particle size of 42 ± 2 nm was obtained. PL emission was observed at 507 nm and a shoulder at 560 nm with an excitation wavelength of 460 nm. Auger electron spectroscopy and Cathodoluminescence (CL) were used to monitor the changes in the surface composition of the CaS:Ce 3+ nanocrystalline phosphors during electron bombardment in an O 2 environment. The effect of different oxygen pressures ranging from 1 × 10 -8 to 1 × 10 -6 Torr on the CL intensity was also investigated. A CaSO 4 layer was observed on the surface after the electron beam degradation. The CL intensity was found to decrease up to 30% of its original intensity at 1 × 10 -6 Torr oxygen pressure after an electron dose of 50 C/cm 2. The formation of oxygen defects during electron bombardment may also be responsible for the decrease in CL intensity.

  14. Laser-induced reduction of a dye characterised by a high triplet-state yield and dissolved in a polymer

    SciTech Connect

    Sizykh, A G; Tarakanova, E A; Tatarinova, L L

    2000-01-31

    An investigation was made of the photoreduction kinetics of a dye in a solid polymer solution under the influence of laser radiation corresponding to the band of the first singlet - singlet transition. Participation of higher triplet states was considered in a model of the photoreduction of a dye characterised by a high intersystem crossing yield. An analytic solution was obtained for a system of kinetic equations. This solution takes into account the difference between the photoprocess rates. It is shown that a linear dependence of the effective dye-photoreduction rate on the laser radiation intensity can serve as a test of the participation of higher triplet states in the reaction. A comparison of the theoretical and experimental results obtained in the present study is used to determine the ratio of the photoreduction and deactivation rate constants of the higher triplet state of eosin K. (interaction of laser radiation with matter. laser plasma)

  15. Luminescence studies on electron and structural states in dielectrics under irradiation

    NASA Astrophysics Data System (ADS)

    Plaksin, O. A.; Stepanov, V. A.; Stepanov, P. A.; Chernov, V. M.; Skuratov, V. A.

    1996-10-01

    Spectra of radiation-induced luminescence (RIL) and photoluminescence (PL) of Al 2O 3 and BeAl 2O 4:Cr 3- single crystals and BN ceramics have been obtained. In Al 2O 3 under 8 MeV proton irradiation, the recharging of defects causing RIL has been shown to occur in the track vicinity of 10 -6 cm size. After neutron irradiation, an essentially non-equilibrium distribution of Cr 3+ impurities over structurally distinguishable sites in the crystal lattice of BeAl 2O 4 was registered by PL spectroscopy. An effective temperature characterising this distribution under neutron irradiation exceeds the melting point of the material. The RIL and PL of BN were caused by colour centres on grain boundaries. Radiation-induced structural transformations in BN ceramics under neutron and 26.7 MeV Ne ion irradiation principally occur on the grain boundaries but not in the bulk of grains.

  16. Defect-Related Luminescent Hydroxyapatite-Enhanced Osteogenic Differentiation of Bone Mesenchymal Stem Cells Via an ATP-Induced cAMP/PKA Pathway.

    PubMed

    Wang, Chao; Liu, Dandan; Zhang, Cuimiao; Sun, Jiadong; Feng, Weipei; Liang, Xing-Jie; Wang, Shuxiang; Zhang, Jinchao

    2016-05-11

    Novel defect-related hydroxyapatite (DHAP), which combines the advantages of HAP and defect-related luminescence, has the potential application in tissue engineering and biomedical area, because of its excellent capability of monitoring the osteogenic differentiation and material biodegradation. Although the extracellular mechanism of DHAP minerals and PO4(3-) functioning in osteogenic differentiation has been widely studied, the intracellular molecular mechanism through which PO4(3-) mediates osteogenesis of bone mesenchymal stem cells (BMSCs) is not clear. We examined a previously unknown molecular mechanism through which PO4(3-) promoted osteogenesis of BMSCs with an emphasis on adenosine-triphosphate (ATP)-induced cAMP/PKA pathway. Our studies showed that DHAP could be uptaken into lysosome, in which PO4(3-) was released from DHAP, because of the acid environment of lysosome. The released PO4(3-) interacted with ADP to form ATP, and then degraded into adenosine, an ATP metabolite, which interacted with A2b adenosine receptor to activate the cAMP/PKA pathway, resulting in the high expression of osteogenesis-related genes, such as Runx2, BMP-2, and OCN. These findings first revealed the function of ATP-metabolism in bone physiological homeostasis, which may be developed to cure bone metabolic diseases.

  17. Bifunctional Zn(II)Ln(III) dinuclear complexes combining field induced SMM behavior and luminescence: enhanced NIR lanthanide emission by 9-anthracene carboxylate bridging ligands.

    PubMed

    Palacios, María A; Titos-Padilla, Silvia; Ruiz, José; Herrera, Juan Manuel; Pope, Simon J A; Brechin, Euan K; Colacio, Enrique

    2014-02-03

    There were new dinuclear Zn(II)-Ln(III) complexes of general formulas [Zn(μ-L)(μ-OAc)Ln(NO3)2] (Ln(III) = Tb (1), Dy (2), Er (3), and Yb (4)), [Zn(μ-L)(μ-NO3)Er(NO3)2] (5), [Zn(H2O)(μ-L)Nd(NO3)3]·2CH3OH (6), [Zn(μ-L)(μ-9-An)Ln(NO3)2]·2CH3CN (Ln(III) = Tb (7), Dy (8), Er (9), Yb(10)), [Zn(μ-L)(μ-9-An)Yb(9-An)(NO3)3]·3CH3CN (11), [Zn(μ-L)(μ-9-An)Nd(9-An)(NO3)3]·2CH3CN·3H2O (12), and [Zn(μ-L)(μ-9-An)Nd(CH3OH)2(NO3)]ClO4·2CH3OH (13) prepared from the reaction of the compartmental ligand N,N',N″-trimethyl-N,N″-bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylenetriamine (H2L), with ZnX2·nH2O (X = NO3(-) or OAc(-)) salts, Ln(NO3)3·nH2O, and, in some instances, 9-anthracenecarboxylate anion (9-An). In all these complexes, the Zn(II) ions invariably occupy the internal N3O2 site whereas the Ln(III) ions show preference for the O4 external site, giving rise to a Zn(μ-diphenoxo)Ln bridging fragment. Depending on the Zn(II) salt and solvent used in the reaction, a third bridge can connect the Zn(II) and Ln(III) metal ions, giving rise to triple-bridged diphenoxoacetate in complexes 1-4, diphenoxonitrate in complex 5, and diphenoxo(9-anthracenecarboxylate) in complexes 8-13. Dy(III) and Er(III) complexes 2, 8 and 3, 5, respectively, exhibit field induced single molecule magnet (SMM) behavior, with Ueff values ranging from 11.7 (3) to 41(2) K. Additionally, the solid-state photophysical properties of these complexes are presented showing that ligand L(2-) is able to sensitize Tb(III)- and Dy(III)-based luminescence in the visible region through an energy transfer process (antenna effect). The efficiency of this process is much lower when NIR emitters such as Er(III), Nd(III), and Yb(III) are considered. When the luminophore 9-anthracene carboxylate is incorporated into these complexes, the NIR luminescence is enhanced which proves the efficiency of this bridging ligand to act as antenna group. Complexes 2, 3, 5, and 8 can be considered as dual materials

  18. Dependence of sonochemical luminescence on various sound fields

    PubMed

    Yanagida; Masubuchi; Minagawa; Takimoto; Ogata; Koyama

    2000-03-01

    To understand the effect of the sound field on sonochemical luminescence, the exact sound pressure must be determined in each field. In this study it was determined by the Shlieren method, which measures the sound pressure without mixing the sound fields. We compared the efficiency of the sonochemical luminescence in three different ways: changing the diameter of the transducer, combining two transducers to obtain crossed propagating directions and surrounding the sound field by a glass cylinder. In the last case cylinders with various sizes were studied. We found that (i) at the same sound pressure, the larger transducer induces stronger luminescence per unit volume, (ii) driving two transducers produces stronger luminescence than the sum of each transducer and (iii) a glass cylinder surrounding the sound field induces stronger luminescence.

  19. A cell-based, multiparametric sensor approach characterises drug-induced cytotoxicity in human liver HepG2 cells.

    PubMed

    Seeland, Swen; Török, Michael; Kettiger, Helene; Treiber, Alexander; Hafner, Mathias; Huwyler, Jörg

    2013-04-01

    Drug-induced toxicity is of considerable concern in drug discovery and development, placing emphasis on the need for predictive in vitro technologies that identify potential cytotoxic side effects of drugs. A label-free, real-time, multiparametric cytosensor system has therefore been established for in vitro assessment of drug-induced toxicity. The system is based on monitoring cellular oxygen consumption, acidification and impedance of human hepatocarcinoma-derived HepG2 cells. The read-out derived from the multiparametric cytosensor system has been optimised and permits sensitive, reliable, and simultaneous recording of cell physiological signals, such as metabolic activity, cellular respiration and morphological changes and cell adhesion upon exposure to a drug. Analysis of eight prototypic reference drugs revealed distinct patterns of drug-induced physiological signals. Effects proved to be rigidly concentration-dependent. Based on signal patterns and reversibility of the observed effects, compounds could be classified based as triggering mechanisms of respiratory or metabolic stress or conditions leading to cell death (necrosis-like and apoptosis-like). A test-flag-risk mitigation strategy is proposed to address potential risks for drug-induced cytotoxicity.

  20. Size/morphology induced tunable luminescence in upconversion crystals: ultra-strong single-band emission and underlying mechanisms

    NASA Astrophysics Data System (ADS)

    Wang, Zhaofeng; Zeng, Songshan; Yu, Jingfang; Ji, Xiaoming; Zeng, Huidan; Xin, Shuangyu; Wang, Yuhua; Sun, Luyi

    2015-05-01

    In this work, we present a two-step method to controllably synthesize novel and highly efficient upconversion materials, Lu5O4F7:Er3+,Yb3+ nano/micro-crystals, and investigate their size/morphology induced tunable upconversion properties. In addition to the common phenomenon aroused by a surface quenching effect, direct experimental evidence for the regulation of phonon modes is obtained in nanoparticles. The findings in this work advance the existing mechanisms for the general explanation of size/morphology induced upconversion features. Because of the adjustment of phonon energy and density as well as the surface quenching effect, the biocompatible Lu5O4F7:Er3+,Yb3+ nanoparticles exhibit an ultra-strong single-band red upconversion, rendering them promising for biomedical applications.In this work, we present a two-step method to controllably synthesize novel and highly efficient upconversion materials, Lu5O4F7:Er3+,Yb3+ nano/micro-crystals, and investigate their size/morphology induced tunable upconversion properties. In addition to the common phenomenon aroused by a surface quenching effect, direct experimental evidence for the regulation of phonon modes is obtained in nanoparticles. The findings in this work advance the existing mechanisms for the general explanation of size/morphology induced upconversion features. Because of the adjustment of phonon energy and density as well as the surface quenching effect, the biocompatible Lu5O4F7:Er3+,Yb3+ nanoparticles exhibit an ultra-strong single-band red upconversion, rendering them promising for biomedical applications. Electronic supplementary information (ESI) available: Crystal structure analysis, UV-Vis absorption spectra, SEM micrographs, surface micro-structure investigation, biocompatibility of Lu5O4F7: Er3+, Yb3+, as well as morphology and upconversion properties of the control sample NaYF4: Er3+, Yb3+. See DOI: 10.1039/c5nr01008j

  1. Argon-ion-induced formation of nanoporous GaSb layer: Microstructure, infrared luminescence, and vibrational properties

    SciTech Connect

    Datta, D. P.; Som, T.; Kanjilal, A.; Satpati, B.; Das, T. D.; Kanjilal, D.

    2014-07-21

    Room temperature implantation of 60 keV Ar{sup +}-ions in GaSb to the fluences of 7 × 10{sup 16} to 3 × 10{sup 18} ions cm{sup −2} is carried out at two incidence angles, viz 0° and 60°, leading to formation of a nanoporous layer. As the ion fluence increases, patches grow on the porous layer under normal ion implantation, whereas the porous layer gradually becomes embedded under a rough top surface for oblique incidence of ions. Grazing incidence x-ray diffraction and cross-sectional transmission electron microscopy studies reveal the existence of nanocrystallites embedded in the ion-beam amorphized GaSb matrix up to the highest fluence used in our experiment. Oxidation of the nanoporous layers becomes obvious from x-ray photoelectron spectroscopy and Raman mapping. The correlation of ion-beam induced structural modification with photoluminescence signals in the infrared region has further been studied, showing defect induced emission of additional peaks near the band edge of GaSb.

  2. Advanced synchronous luminescence system

    DOEpatents

    Vo-Dinh, Tuan

    1997-01-01

    A method and apparatus for determining the condition of tissue or otherwise making chemical identifications includes exposing the sample to a light source, and using a synchronous luminescence system to produce a spectrum that can be analyzed for tissue condition.

  3. Luminescent aryl-group eleven metal complexes.

    PubMed

    López-de-Luzuriaga, José M; Monge, Miguel; Olmos, M Elena

    2017-02-14

    Among the coinage metal complexes displaying luminescent properties, those bearing C-donor aryl ligands have an increasing part in the chemistry of these metals. These types of ligands confer a high kinetic and thermodynamic stability on the complexes, but they can also be involved in the photoluminescent behaviour of the complexes. The development of new aryl-containing complexes of group eleven metals, the study of their photoluminescent properties and their related properties and applications are discussed in this perspective. Among these, luminescent gold(i) and gold(iii) compounds are being intensively used for the development of new properties with potential applications such as, for instance, electroluminescence, triboluminescence, mechanochromism, aggregated induced emissions, quenching, luminescent liquid crystals, low molecular weight gelators and photocatalysts, among others.

  4. Structured luminescence conversion layer

    DOEpatents

    Berben, Dirk; Antoniadis, Homer; Jermann, Frank; Krummacher, Benjamin Claus; Von Malm, Norwin; Zachau, Martin

    2012-12-11

    An apparatus device such as a light source is disclosed which has an OLED device and a structured luminescence conversion layer deposited on the substrate or transparent electrode of said OLED device and on the exterior of said OLED device. The structured luminescence conversion layer contains regions such as color-changing and non-color-changing regions with particular shapes arranged in a particular pattern.

  5. Swift heavy ion induced structural and luminescence characterization of Y₂O₃:Eu³⁺ phosphor: a comparative study.

    PubMed

    Som, S; Sharma, S K; Lochab, S P

    2014-08-01

    We report a comparative study on structural and thermoluminescence modifications of Y2O3:Eu(3+) phosphor induced by 150 MeV Ni(7+), 120 MeV Ag(9+) and 110 MeV Au(8+) swift heavy ions (SHI) in the fluence range 1 × 10(11) to 1 × 10(13) ions/cm(2). X-Ray diffraction and transition electron microscopy studies confirm the loss of crystallinity of the phosphors after ion irradiation, which is greater in the case of Au ion irradiation. Structural refinement using the Rietveld method yields the various structural parameters of ion-irradiated phosphors. Thermoluminescence glow curves of ion-irradiated phosphors show a small shift in the position of the peaks, along with an increase in intensity with ion fluence. Stopping range of ions in Matter (SRIM) calculations were performed to correlate the change in thermoluminescence properties of various ion-irradiated phosphors. It shows that the defects created by 110 MeV Au(8+) ions are greater in number. Trapping parameters of ion-irradiated phosphors were calculated from thermoluminescence data using various glow curve analysis methods.

  6. Molecular characterisation of murine acute myeloid leukaemia induced by 56Fe ion and 137Cs gamma ray irradiation

    PubMed Central

    Bacher, Jeffery W.

    2013-01-01

    Exposure to sparsely ionising gamma- or X-ray irradiation is known to increase the risk of leukaemia in humans. However, heavy ion radiotherapy and extended space exploration will expose humans to densely ionising high linear energy transfer (LET) radiation for which there is currently no understanding of leukaemia risk. Murine models have implicated chromosomal deletion that includes the hematopoietic transcription factor gene, PU.1 (Sfpi1), and point mutation of the second PU.1 allele as the primary cause of low-LET radiation-induced murine acute myeloid leukaemia (rAML). Using array comparative genomic hybridisation, fluorescence in situ hybridisation and high resolution melt analysis, we have confirmed that biallelic PU.1 mutations are common in low-LET rAML, occurring in 88% of samples. Biallelic PU.1 mutations were also detected in the majority of high-LET rAML samples. Microsatellite instability was identified in 42% of all rAML samples, and 89% of samples carried increased microsatellite mutant frequencies at the single-cell level, indicative of ongoing instability. Instability was also observed cytogenetically as a 2-fold increase in chromatid-type aberrations. These data highlight the similarities in molecular characteristics of high-LET and low-LET rAML and confirm the presence of ongoing chromosomal and microsatellite instability in murine rAML. PMID:22987027

  7. Characterisation of SalRAB a salicylic acid inducible positively regulated efflux system of Rhizobium leguminosarum bv viciae 3841.

    PubMed

    Tett, Adrian J; Karunakaran, Ramakrishnan; Poole, Philip S

    2014-01-01

    Salicylic acid is an important signalling molecule in plant-microbe defence and symbiosis. We analysed the transcriptional responses of the nitrogen fixing plant symbiont, Rhizobium leguminosarum bv viciae 3841 to salicylic acid. Two MFS-type multicomponent efflux systems were induced in response to salicylic acid, rmrAB and the hitherto undescribed system salRAB. Based on sequence similarity salA and salB encode a membrane fusion and inner membrane protein respectively. salAB are positively regulated by the LysR regulator SalR. Disruption of salA significantly increased the sensitivity of the mutant to salicylic acid, while disruption of rmrA did not. A salA/rmrA double mutation did not have increased sensitivity relative to the salA mutant. Pea plants nodulated by salA or rmrA strains did not have altered nodule number or nitrogen fixation rates, consistent with weak expression of salA in the rhizosphere and in nodule bacteria. However, BLAST analysis revealed seventeen putative efflux systems in Rlv3841 and several of these were highly differentially expressed during rhizosphere colonisation, host infection and bacteroid differentiation. This suggests they have an integral role in symbiosis with host plants.

  8. Characterisation of spatial neglect induced by unilateral 6-OHDA lesions on a choice reaction time task in rats.

    PubMed

    Heuer, Andreas; Dunnett, Stephen B

    2013-01-15

    Unilateral dopamine depletion and excitotoxic lesions of the striatum have been shown to induce a contralateral neglect when rats have to respond in a choice reaction time setting. Whereas, in a lateralised setting when response options are to either side of the animal's head all contralateral responding is impaired, testing animals only on one side of the head per day but with a near and far response option, rats are able to correctly respond to contralateral stimuli, but rather bias their responses towards the near hole. Here, we further investigated the nature of the contralateral neglect in egocentric space coding in more detail. Firstly, we tested the effects of near-complete unilateral dopamine depletion on this type of task. Secondly, previous observations suggested that lesioned rats shifted their response strategy which resulted in a response bias towards the most proximal location in contralateral space. In order to "encourage" dopamine depleted rats to respond to the neglected response location we implemented an error correction procedure to the task. Near-complete unilateral dopamine depletion, via 6-hydroxydopamine infusions into the medial forebrain bundle of female Lister Hood rats, resulted in a reduction of usable trials, a near hole bias when animals were tested on the side contralateral to the lesion, as well as increased reaction and movement time latencies. The introduction of an error-correction procedure had no effect on the animals' response bias towards the near contralateral location. Probe trials showed that the bias is most likely the result of responses being misdirected when in a choice situation. The findings further highlight the role of dopamine and an intact striatum to code responses into egocentrically defined space.

  9. In-air broad beam ionoluminescence microscopy as a tool for rocks and stone artworks characterisation.

    PubMed

    Lo Giudice, Alessandro; Re, Alessandro; Angelici, Debora; Calusi, Silvia; Gelli, Nicla; Giuntini, Lorenzo; Massi, Mirko; Pratesi, Giovanni

    2012-07-01

    Broad beam ionoluminescence (IL) microscopy is a promising technique for the non-destructive characterisation of rocks and stone objects. Luminescence imaging by means of broad ion beams has been sporadically used by other authors but, to our knowledge, its potential has not yet been fully investigated, neither in geological science nor in other fields. The in-air broad beam IL microscope was developed and installed at the INFN-LABEC external microbeam in Florence. Similar to the cathodoluminescence (CL) microscope, the apparatus exploits a CCD colour camera collecting images (few square millimetres wide, with ~10-μm spatial resolution) of the luminescence emitted by the sample hit by a defocused megaelectron volt (MeV) proton beam. The main differences with the well-established and widespread CL are the possibility of working in air (no sampling or conductive coatings required) and the possibility of combining the analysis with microbeam analysis, such as, for example, μ-IL and μ-PIXE (particle-induced X-ray emission). To show the potential of the technique, IL images of thin sections of lapis lazuli are compared with those obtained by means of an in-vacuum cold CL. An application to the study of stone artworks is also reported. This technique and apparatus will provide a valuable help for interdisciplinary applications, e.g. in geological sciences and in the cultural heritage field.

  10. The mensuration of delayed luminescence on ginseng

    NASA Astrophysics Data System (ADS)

    Xiang, Fenghua; Bai, Hua; Tang, Guoqing

    2008-12-01

    In this paper, the delayed luminescence of ginseng produced from two different areas was determined with the self built bioluminescence detecting system. And the attenuation curve of bioluminescence of the experimental samples were studied, before and after the samples extracted by 58% alcohol. We primarily gave out the parameters describing emitting characteristic. Using the method of optic induced bioluminescence, we also determined the weak luminescence emitting from the ginseng tuber, and find the intensity and decay time having obvious difference from skin and core, with these data we can distinguish the producing area and feature of the ginseng. In the experiment, the light-induce luminescence of the sample was menstruated, which has been infused by water and 58% alcohol; the difference between two kinds of samples which were infused and not infused has been delivered. In order to investigate the effect of excitation-light spectrum component to delayed luminescence of ginseng, a light filter witch allow a wavelength scope of 225nm~420nm pass through was installed between the light source and sample, keeping other work condition unchanged, the bioluminescence was also determined. For investigating the effect of extracting to emitting, the absorption spectrum of above samples ware studied, and the time-sequence of absorption spectrum was obtained. Based on the data obtained from our experiment, we analyzed the radiation mechanism of ginseng slice and tuber.

  11. Quantitative Luminescence Imaging System

    SciTech Connect

    Batishko, C.R.; Stahl, K.A.; Fecht, B.A.

    1992-12-31

    The goal of the MEASUREMENT OF CHEMILUMINESCENCE project is to develop and deliver a suite of imaging radiometric instruments for measuring spatial distributions of chemiluminescence. Envisioned deliverables include instruments working at the microscopic, macroscopic, and life-sized scales. Both laboratory and field portable instruments are envisioned. The project also includes development of phantoms as enclosures for the diazoluminomelanin (DALM) chemiluminescent chemistry. A suite of either phantoms in a variety of typical poses, or phantoms that could be adjusted to a variety of poses, is envisioned. These are to include small mammals (rats), mid-sized mammals (monkeys), and human body parts. A complete human phantom that can be posed is a long-term goal of the development. Taken together, the chemistry and instrumentation provide a means for imaging rf dosimetry based on chemiluminescence induced by the heat resulting from rf energy absorption. The first delivered instrument, the Quantitative Luminescence Imaging System (QLIS), resulted in a patent, and an R&D Magazine 1991 R&D 100 award, recognizing it as one of the 100 most significant technological developments of 1991. The current status of the project is that three systems have been delivered, several related studies have been conducted, two preliminary human hand phantoms have been delivered, system upgrades have been implemented, and calibrations have been maintained. Current development includes sensitivity improvements to the microscope-based system; extension of the large-scale (potentially life-sized targets) system to field portable applications; extension of the 2-D large-scale system to 3-D measurement; imminent delivery of a more refined human hand phantom and a rat phantom; rf, thermal and imaging subsystem integration; and continued calibration and upgrade support.

  12. Quantitative luminescence imaging system

    NASA Astrophysics Data System (ADS)

    Batishko, C. R.; Stahl, K. A.; Fecht, B. A.

    The goal of the Measurement of Chemiluminescence project is to develop and deliver a suite of imaging radiometric instruments for measuring spatial distributions of chemiluminescence. Envisioned deliverables include instruments working at the microscopic, macroscopic, and life-sized scales. Both laboratory and field portable instruments are envisioned. The project also includes development of phantoms as enclosures for the diazoluminomelanin (DALM) chemiluminescent chemistry. A suite of either phantoms in a variety of typical poses, or phantoms that could be adjusted to a variety of poses, is envisioned. These are to include small mammals (rats), mid-sized mammals (monkeys), and human body parts. A complete human phantom that can be posed is a long-term goal of the development. Taken together, the chemistry and instrumentation provide a means for imaging rf dosimetry based on chemiluminescence induced by the heat resulting from rf energy absorption. The first delivered instrument, the Quantitative Luminescence Imaging System (QLIS), resulted in a patent, and an R&D Magazine 1991 R&D 100 award, recognizing it as one of the 100 most significant technological developments of 1991. The current status of the project is that three systems have been delivered, several related studies have been conducted, two preliminary human hand phantoms have been delivered, system upgrades have been implemented, and calibrations have been maintained. Current development includes sensitivity improvements to the microscope-based system; extension of the large-scale (potentially life-sized targets) system to field portable applications; extension of the 2-D large-scale system to 3-D measurement; imminent delivery of a more refined human hand phantom and a rat phantom; rf, thermal and imaging subsystem integration; and continued calibration and upgrade support.

  13. Band-gap engineering by molecular mechanical strain-induced giant tuning of the luminescence in colloidal amorphous porous silicon nanostructures.

    PubMed

    Mughal, A; El Demellawi, J K; Chaieb, Sahraoui

    2014-12-14

    Nano-silicon is a nanostructured material in which quantum or spatial confinement is the origin of the material's luminescence. When nano-silicon is broken into colloidal crystalline nanoparticles, its luminescence can be tuned across the visible spectrum only when the sizes of the nanoparticles, which are obtained via painstaking filtration methods that are difficult to scale up because of low yield, vary. Bright and tunable colloidal amorphous porous silicon nanostructures have not yet been reported. In this letter, we report on a 100 nm modulation in the emission of freestanding colloidal amorphous porous silicon nanostructures via band-gap engineering. The mechanism responsible for this tunable modulation, which is independent of the size of the individual particles and their distribution, is the distortion of the molecular orbitals by a strained silicon-silicon bond angle. This mechanism is also responsible for the amorphous-to-crystalline transformation of silicon.

  14. Lunar luminescence measurements

    NASA Technical Reports Server (NTRS)

    Morgan, T. H.

    1983-01-01

    Spectra of lunar sites obtained in June 1983 have been analyzed for residual luminescence using the spectral line depth technique. The results or three sites each at three wavelengths are presented. The sites observed were Mare Crisium, Kepler, and Aristarchus. In each case, the value quoted was based not only on the strong Fraunhofer line in the spectral range covered but also on from 11 to 21 weaker lines within 80 A of the strongest feature. These data do not support previous observations. The values given do not indicate a greatly reddened spectrum, and the luminescence spectrum of the mare site is not significantly different from the two young crater sites. These observations cannot be adequately explained by thermal luminescence, theories of direct excitation are also unable to explain the strength of the flux.

  15. Bifunctional star-burst amorphous molecular materials for OLEDs: achieving highly efficient solid-state luminescence and carrier transport induced by spontaneous molecular orientation.

    PubMed

    Kim, Jun Yun; Yasuda, Takuma; Yang, Yu Seok; Adachi, Chihaya

    2013-05-21

    Bifunctional star-burst amorphous molecular materials displaying both efficient solid-state luminescence and high hole-transport properties are developed in this study. A high external electroluminescence quantum efficiency up to 5.9% is attained in OLEDs employing the developed amorphous materials. It is revealed that the spontaneous horizontal orientation of these light-emitting molecules in their molecular-condensed states leads to a remarkable enhancement of the electroluminescence efficiencies and carrier-transport properties.

  16. Magnetic and fluorescent Gd2O3:Yb(3+)/Ln(3+) nanoparticles for simultaneous upconversion luminescence/MR dual modal imaging and NIR-induced photodynamic therapy.

    PubMed

    Liu, Jun; Huang, Long; Tian, Xiumei; Chen, Xiaoming; Shao, Yuanzhi; Xie, Fukang; Chen, Dihu; Li, Li

    The development of upconversion nanoparticles (UCNs) for theranostics application is a new strategy toward the accurate diagnosis and efficient treatment of cancer. Here, magnetic and fluorescent lanthanide-doped gadolinium oxide (Gd2O3) UCNs with bright upconversion luminescence (UCL) and high longitudinal relaxivity (r1) are used for simultaneous magnetic resonance imaging (MRI)/UCL dual-modal imaging and photodynamic therapy (PDT). In vitro and in vivo MRI studies show that these products can serve as good MRI contrast agents. The bright upconversion luminescence of the products allows their use as fluorescence nanoprobes for live cells imaging. We also utilized the luminescence-emission capability of the UCNs for the activation of a photosensitizer to achieve significant PDT results. To the best of our knowledge, this study is the first use of lanthanide-doped Gd2O3 UCNs in a theranostics application. This investigation provides a useful platform for the development of Gd2O3-based UCNs for clinical diagnosis, treatment, and imaging-guided therapy of cancer.

  17. Magnetic and fluorescent Gd2O3:Yb3+/Ln3+ nanoparticles for simultaneous upconversion luminescence/MR dual modal imaging and NIR-induced photodynamic therapy

    PubMed Central

    Liu, Jun; Huang, Long; Tian, Xiumei; Chen, Xiaoming; Shao, Yuanzhi; Xie, Fukang; Chen, Dihu; Li, Li

    2017-01-01

    The development of upconversion nanoparticles (UCNs) for theranostics application is a new strategy toward the accurate diagnosis and efficient treatment of cancer. Here, magnetic and fluorescent lanthanide-doped gadolinium oxide (Gd2O3) UCNs with bright upconversion luminescence (UCL) and high longitudinal relaxivity (r1) are used for simultaneous magnetic resonance imaging (MRI)/UCL dual-modal imaging and photodynamic therapy (PDT). In vitro and in vivo MRI studies show that these products can serve as good MRI contrast agents. The bright upconversion luminescence of the products allows their use as fluorescence nanoprobes for live cells imaging. We also utilized the luminescence-emission capability of the UCNs for the activation of a photosensitizer to achieve significant PDT results. To the best of our knowledge, this study is the first use of lanthanide-doped Gd2O3 UCNs in a theranostics application. This investigation provides a useful platform for the development of Gd2O3-based UCNs for clinical diagnosis, treatment, and imaging-guided therapy of cancer. PMID:28031709

  18. Determination of uranium(VI) sorbed species in calcium silicate hydrate phases: a laser-induced luminescence spectroscopy and batch sorption study.

    PubMed

    Tits, Jan; Geipel, Gerhard; Macé, Nathalie; Eilzer, Manuela; Wieland, Erich

    2011-07-01

    Batch sorption experiments and time-resolved luminescence spectroscopy investigations were carried out to study the U(VI) speciation in calcium silicate hydrates for varying chemical conditions representing both fresh and altered cementitious environments. U(VI) uptake was found to be fast and sorption distribution ratios (R(d) values) were very high indicating strong uptake by the C-S-H phases. In addition a strong dependence of pH and solid composition (Ca:Si mol ratio) was observed. U(VI) luminescence spectroscopy investigations showed that the U(VI) solid speciation continuously changed over a period up to 6 months in contrast to the fast sorption kinetics observed in the batch sorption studies. Decay profile analysis combined with factor analysis of series of spectra of U(VI)-C-S-H suspensions, recorded with increasing delay times, revealed the presence of four luminescent U(VI) species in C-S-H suspensions, in agreement with the batch sorption data. Along with the aqueous UO(2)(OH)(4)(2-) species and a Ca-uranate precipitate, two different sorbed species were identified which are either bound to silanol groups on the surface or incorporated in the interlayer of the C-S-H structure.

  19. Structural changes and relaxations monitored by luminescence.

    PubMed

    Wang, Y; Yang, B; Townsend, P D

    2013-01-01

    Luminescence data have often been used to study imperfections and to characterize lattice distortions because the signals are sensitive to changes of structure and composition. Previous studies have included intentionally added probe ions such as rare earth ions to sense distortions in local crystal fields caused by modified structural environments. An under-exploited extension of this approach was to use luminescence to monitor crystalline phase changes. A current overview of this new and powerful technique shows that continuous scanning of the sample temperatures immediately offered at least three types of signatures for phase transitions. Because of high sensitivity, luminescence signals were equally responsive to structural changes from inclusions and nanoparticles. These coupled to the host material via long-range interactions and modified the host signals. Two frequently observed examples that are normally overlooked are from nanoparticle inclusions of water and CO2. Examples also indicated that phase transitions were detected in more diverse materials such as superconductors and fullerenes. Finally, luminescence studies have shown that in some crystalline examples, high dose ion implantation of surface layers could induce relaxations and/or structural changes of the entire underlying bulk material. This was an unexpected result and therefore such a possibility has not previously been explored. However, the implications for ion implication are significant and could be far more general than the examples mentioned here.

  20. CCD Luminescence Camera

    NASA Technical Reports Server (NTRS)

    Janesick, James R.; Elliott, Tom

    1987-01-01

    New diagnostic tool used to understand performance and failures of microelectronic devices. Microscope integrated to low-noise charge-coupled-device (CCD) camera to produce new instrument for analyzing performance and failures of microelectronics devices that emit infrared light during operation. CCD camera also used to indentify very clearly parts that have failed where luminescence typically found.

  1. Advanced synchronous luminescence system

    DOEpatents

    Vo-Dinh, T.

    1997-02-04

    A method and apparatus are disclosed for determining the condition of tissue or otherwise making chemical identifications includes exposing the sample to a light source, and using a synchronous luminescence system to produce a spectrum that can be analyzed for tissue condition. 14 figs.

  2. EPR and luminescence studies of the radiation induced Eu2+ centers in the EuAl3(BO3)4 single crystals

    NASA Astrophysics Data System (ADS)

    Prokhorov, A. A.; Chernush, L. F.; Babin, V.; Buryi, M.; Savchenko, D.; Lančok, J.; Nikl, M.; Prokhorov, A. D.

    2017-04-01

    We have studied the X-ray irradiated EuAl3(BO3)4 single crystals by means of luminescence and electron paramagnetic resonance (EPR) spectroscopy. It was found that the X-ray irradiation modifies the color of the EuAl3(BO3)4 crystal and leads to the formation of a stable Eu2+ centers from the Eu3+ centers located in a host matrix. Annealing of the crystal at 600 °C leads to the restoration of the original color and the disappearance of Eu2+ centers. The EPR and luminescence spectra of the Eu2+ ion were studied in a wide temperature range. The angular dependence of Eu2+ EPR spectra is described by an axial spin Hamiltonian characterized by the spin of S = 7/2 with the following parameters: gz = gx = 1.991 (1); b20 = -267,86 (16)*10-4cm-1; b40 = -4,20 (8)* 10-4cm-1; b60 = 0,37 (13)* 10-4cm-1; A (151) = 31,4 (3)* 10-4cm-1; A (153) = 13,9 (3)* 10-4cm-1. Based on the comparison of spin Hamiltonian parameters of Eu2+ and Gd3+ ions, it was concluded that Eu2+ ion located at the Eu3+ site in the EuAl3(BO3)4 crystal lattice. Within the framework of the superposition model, the distortions introduced to the local environment by the Eu2+ and Gd3+ ions were analyzed. In the luminescence spectra, the bands associated with the Eu2+ and Eu3+ ions are detected. The photoluminescence decay kinetics of Eu3+-related emission (614 nm) has a single-exponential character, whereas the Eu2+-related band (323 nm) possess more complicated decay kinetics behavior that may point to the Eu2+ excited state ionization and its delayed recombination.

  3. Control of luminescence from pygmy shark (Squaliolus aliae) photophores.

    PubMed

    Claes, Julien M; Ho, Hsuan-Ching; Mallefet, Jérôme

    2012-05-15

    The smalleye pygmy shark (Squaliolus aliae) is a dwarf pelagic shark from the Dalatiidae family that harbours thousands of tiny photophores. In this work, we studied the organisation and physiological control of these photogenic organs. Results show that they are mainly situated on the ventral side of the shark, forming a homogeneous ventral photogenic area that appears well suited for counterillumination, a well-known camouflage technique of pelagic organisms. Isolated ventral skin patches containing photophores did not respond to classical neurotransmitters and nitric oxide but produced light after melatonin (MT) application. Prolactin and α-melanocyte-stimulating hormone inhibited this hormonally induced luminescence as well as the spontaneous luminescence from the photogenic tissue. The action of MT seems to be mediated by binding to the MT(2) receptor subtype, as the MT(2) receptor agonist 4P-PDOT inhibited the luminescence induced by this hormone. Binding to this receptor probably decreases the intracellular cAMP concentration because forskolin inhibited spontaneous and MT-induced luminescence. In addition, a GABA inhibitory tonus seems to be present in the photogenic tissue as well, as GABA inhibited MT-induced luminescence and the application of bicuculline provoked luminescence from S. aliae photophores. Similarly to what has been found in Etmopteridae, the other luminous shark family, the main target of the luminescence control appears to be the melanophores covering the photocytes. Results suggest that bioluminescence first appeared in Dalatiidae when they adopted a pelagic style at the Cretaceous/Tertiary boundary, and was modified by Etmopteridae when they started to colonize deep-water niches and rely on this light for intraspecific behaviours.

  4. Quantitative luminescence imaging system

    DOEpatents

    Erwin, D.N.; Kiel, J.L.; Batishko, C.R.; Stahl, K.A.

    1990-08-14

    The QLIS images and quantifies low-level chemiluminescent reactions in an electromagnetic field. It is capable of real time nonperturbing measurement and simultaneous recording of many biochemical and chemical reactions such as luminescent immunoassays or enzyme assays. The system comprises image transfer optics, a low-light level digitizing camera with image intensifying microchannel plates, an image process or, and a control computer. The image transfer optics may be a fiber image guide with a bend, or a microscope, to take the light outside of the RF field. Output of the camera is transformed into a localized rate of cumulative digitalized data or enhanced video display or hard-copy images. The system may be used as a luminescent microdosimetry device for radiofrequency or microwave radiation, as a thermal dosimeter, or in the dosimetry of ultra-sound (sonoluminescence) or ionizing radiation. It provides a near-real-time system capable of measuring the extremely low light levels from luminescent reactions in electromagnetic fields in the areas of chemiluminescence assays and thermal microdosimetry, and is capable of near-real-time imaging of the sample to allow spatial distribution analysis of the reaction. It can be used to instrument three distinctly different irradiation configurations, comprising (1) RF waveguide irradiation of a small Petri-dish-shaped sample cell, (2) RF irradiation of samples in a microscope for the microscopic imaging and measurement, and (3) RF irradiation of small to human body-sized samples in an anechoic chamber. 22 figs.

  5. Quantitative luminescence imaging system

    DOEpatents

    Erwin, David N.; Kiel, Johnathan L.; Batishko, Charles R.; Stahl, Kurt A.

    1990-01-01

    The QLIS images and quantifies low-level chemiluminescent reactions in an electromagnetic field. It is capable of real time nonperturbing measurement and simultaneous recording of many biochemical and chemical reactions such as luminescent immunoassays or enzyme assays. The system comprises image transfer optics, a low-light level digitizing camera with image intensifying microchannel plates, an image process or, and a control computer. The image transfer optics may be a fiber image guide with a bend, or a microscope, to take the light outside of the RF field. Output of the camera is transformed into a localized rate of cumulative digitalized data or enhanced video display or hard-copy images. The system may be used as a luminescent microdosimetry device for radiofrequency or microwave radiation, as a thermal dosimeter, or in the dosimetry of ultra-sound (sonoluminescence) or ionizing radiation. It provides a near-real-time system capable of measuring the extremely low light levels from luminescent reactions in electromagnetic fields in the areas of chemiluminescence assays and thermal microdosimetry, and is capable of near-real-time imaging of the sample to allow spatial distribution analysis of the reaction. It can be used to instrument three distinctly different irradiation configurations, comprising (1) RF waveguide irradiation of a small Petri-dish-shaped sample cell, (2) RF irradiation of samples in a microscope for the microscopie imaging and measurement, and (3) RF irradiation of small to human body-sized samples in an anechoic chamber.

  6. Microstructural lines involving luminescence

    NASA Astrophysics Data System (ADS)

    Shimada, Kazuhiko

    2004-06-01

    Japanese National Printing Bureau has been focused upon the development of anti-copy lines for many years. The basic concept with regard to security measure lies in the merge of art and technology. On this basis, our originally developed anti-copy lines show flexibility to various security designs. Our newest anti-copy lines comprising from the Tri-Branched and Divided Lines shows clearer latent image effect compared to that of our other developed anti-copy lines. However, the anti-copy effect of security printing lines with microstructure is deteriorating due to the emergence of digital image techniques with higher resolution. In this situation, this paper introduces a new security measure comprising from luminescence and security printing lines with microstructure. It gives rise to a latent image effect under UV light due to the characteristic microstructure while visually same density. The principle advantage is that the combination of the anti-copy and luminescent feature strongly enhances its secure effect in documents. There is no necessity of two kinds of inks and any specially designed equipment to produce security documents with microstructural lines involving luminescence.

  7. An Introduction to Luminescence in Inorganic Solids.

    ERIC Educational Resources Information Center

    DeLuca, John A.

    1980-01-01

    Introduces luminescence by characterizing phosphors, describing phosphor phenomena, presenting a configurational coordinate model of characteristic luminescence, and describing some commercial applications of phosphors. (CS)

  8. Neutron dosimetry using optically stimulated luminescence

    NASA Astrophysics Data System (ADS)

    Miller, S. D.; Eschbach, P. A.

    1991-06-01

    The addition of thermoluminescent (TL) materials within hydrogenous matrices to detect neutron induced proton recoils for radiation dosimetry is a well known concept. Previous attempts to implement this technique have met with limited success, primarily due to the high temperatures required for TL readout and the low melting temperatures of hydrogen-rich plastics. Research in recent years PNL has produced a new Optically Stimulated Luminescence (OSL) technique known as the Cooled Optically Stimulated Luminescence (COSL) that offers, for the first time, the capability of performing extremely sensitive radiation dosimetry at low temperatures. In addition to its extreme sensitivity, the COSL technique offers multiple readout capability, limited fading in a one year period, and the capability of analyzing single grains within a hydrogenous matrix.

  9. Luminescence properties of Si-containing porous matrix–PbS nanoparticle systems

    SciTech Connect

    Tarasov, S. A. Aleksandrova, O. A.; Lamkin, I. A.; Maksimov, A. I.; Maraeva, E. V.; Mikhailov, I. I.; Moshnikov, V. A.; Musikhin, S. F.; Nalimova, S. S.; Permyakov, N. V.; Spivak, Yu. M.; Travkin, P. G.

    2015-12-15

    The luminescence properties of systems that contain lead-sulfide nanoparticles deposited onto substrates fabricated from porous silicon, oxidized porous silicon, and porous (tin-oxide)–(silicon-oxide) layers are studied. It is shown that the structure and composition of the matrix induce a strong effect on the luminescence spectra of colloidal quantum dots, defining their emission wavelength.

  10. Quantum confinement effect in 6H-SiC quantum dots observed via plasmon-exciton coupling-induced defect-luminescence quenching

    NASA Astrophysics Data System (ADS)

    Guo, Xiaoxiao; Zhang, Yumeng; Fan, Baolu; Fan, Jiyang

    2017-03-01

    The quantum confinement effect is one of the crucial physical effects that discriminate a quantum material from its bulk material. It remains a mystery why the 6H-SiC quantum dots (QDs) do not exhibit an obvious quantum confinement effect. We study the photoluminescence of the coupled colloidal system of SiC QDs and Ag nanoparticles. The experimental result in conjunction with the theoretical calculation reveals that there is strong coupling between the localized electron-hole pair in the SiC QD and the localized surface plasmon in the Ag nanoparticle. It results in resonance energy transfer between them and resultant quenching of the blue surface-defect luminescence of the SiC QDs, leading to uncovering of a hidden near-UV emission band. This study shows that this emission band originates from the interband transition of the 6H-SiC QDs and it exhibits a remarkable quantum confinement effect.

  11. B-site ordered double perovskite LaBa1-xSrxZnSbO6 (0 ≤ x ≤ 1): Sr(2+)-doping-induced symmetry evolution and structure-luminescence correlations.

    PubMed

    Jiang, Pengfei; Zhou, Zhengyang; Gao, Wenliang; Cong, Rihong; Yang, Tao

    2016-03-07

    The study of perovskites has been active for a long time. Here, we rationally designed and prepared a double perovskite, LaBaZnSbO6, by selecting Zn(2+) and Sb(5+) with large size and charge differences, and, indeed, complete B-site ordering can be achieved. Careful study using powder X-ray diffraction data pinpointed its space group to be I2/m, which has rarely been seen in double perovskites. Thereafter, an interesting observation of Sr(2+)-doping-induced symmetry evolution from I2/m to P21/n was confirmed in the complete solid solutions LaBa1-xSrxZnSbO6, where the tilting system also transferred from a(-)a(-)c(0) to a(-)a(-)c(+). The transition boundary is around x = 0.4. It can also be visualized by the variation of θ (defined as c/[(a + b)/2]), which is associated with the anisotropic shrinkage of the unit cell lattice and indeed shows a minimum at x = 0.4. Such a successive modulation of both the structural symmetry and the average La/Ba/Sr-O bond distances (revealed by Rietveld refinements) motivated us to study the Eu(3+) luminescence in La0.95Eu0.05Ba1-xSrxZnSbO6. Interestingly, the maximum of charge transfer absorption of Eu(3+) shows a precise changing tendency with the A-O bond distances along with the Sr(2+) doping, clearly revealing the structure-luminescence correlations.

  12. Probing structure-induced optical behavior in a new class of self-activated luminescent 0D/1D CaWO₄ metal oxide – CdSe nanocrystal composite heterostructures

    SciTech Connect

    Han, Jinkyu; McBean, Coray; Wang, Lei; Hoy, Jessica; Jaye, Cherno; Liu, Haiqing; Li, Zhuo-Qun; Sfeir, Matthew Y.; Fischer, Daniel A.; Taylor, Gordon T.; Misewich, James A.; Wong, Stanislaus S.

    2015-01-30

    In this report, we synthesize and characterize the structural and optical properties of novel heterostructures composed of (i) semiconducting nanocrystalline CdSe quantum dot (QDs) coupled with (ii) both one and zero-dimensional (1D and 0D) motifs of self-activated luminescence CaWO₄ metal oxides. Specifically, ~4 nm CdSe QDs have been anchored onto (i) high-aspect ratio 1D nanowires, measuring ~230 nm in diameter and ~3 μm in length, as well as onto (ii) crystalline 0D nanoparticles (possessing an average diameter of ~ 80 nm) of CaWO₄ through the mediation of 3-mercaptopropionic acid (MPA) as a connecting linker. Composite formation was confirmed by complementary electron microscopy and spectroscopy (i.e. IR and Raman) data. In terms of luminescent properties, our results show that our 1D and 0D heterostructures evince photoluminescence (PL) quenching and shortened PL lifetimes of CaWO₄ as compared with unbound CaWO₄. We propose that a photo-induced electron transfer process occurs from CaWO₄ to CdSe QDs, a scenario which has been confirmed by NEXAFS measurements and which highlights a decrease in the number of unoccupied orbitals in the conduction bands of CdSe QDs. By contrast, the PL signature and lifetimes of MPA-capped CdSe QDs within these heterostructures do not exhibit noticeable changes as compared with unbound MPA-capped CdSe QDs. The striking difference in optical behavior between CaWO₄ nanostructures and CdSe QDs within our heterostructures can be correlated with the relative positions of their conduction and valence energy band levels. In addition, the PL quenching behaviors for CaWO₄ within the heterostructure configuration were examined by systematically varying (i) the quantities and coverage densities of CdSe QDs as well as (ii) the intrinsic morphology (and by extension, the inherent crystallite size) of CaWO₄ itself.

  13. Strong Magnetic Field Characterisation

    DTIC Science & Technology

    2012-04-01

    coils were driven by a pulsed-power system to generate the fields. All the sources were characterised through a series of measurements and modelling... generated for the coils. Options for further investigation were provided. UNCLASSIFIED UNCLASSIFIED This...investigation. The desired field strength was based on assessments [1] from preliminary magnetohydrodynamic ( MHD ) modelling and while not achievable by

  14. Luminescent macrocyclic lanthanide complexes

    DOEpatents

    Raymond, Kenneth N [Berkeley, CA; Corneillie, Todd M [Campbell, CA; Xu, Jide [Berkeley, CA

    2012-05-08

    The present invention provides a novel class of macrocyclic compounds as well as complexes formed between a metal (e.g., lanthanide) ion and the compounds of the invention. Preferred complexes exhibit high stability as well as high quantum yields of lanthanide ion luminescence in aqueous media without the need for secondary activating agents. Preferred compounds incorporate hydroxy-isophthalamide moieties within their macrocyclic structure and are characterized by surprisingly low, non-specific binding to a variety of polypeptides such as antibodies and proteins as well as high kinetic stability. These characteristics distinguish them from known, open-structured ligands.

  15. Luminescent macrocyclic lanthanide complexes

    DOEpatents

    Raymond, Kenneth N; Corneillie, Todd M; Xu, Jide

    2014-05-20

    The present invention provides a novel class of macrocyclic compounds as well as complexes formed between a metal (e.g., lanthanide) ion and the compounds of the invention. Preferred complexes exhibit high stability as well as high quantum yields of lanthanide ion luminescence in aqueous media without the need for secondary activating agents. Preferred compounds incorporate hydroxy-isophthalamide moieties within their macrocyclic structure and are characterized by surprisingly low, non-specific binding to a variety of polypeptides such as antibodies and proteins as well as high kinetic stability. These characteristics distinguish them from known, open-structured ligands.

  16. Enhanced radiation detectors using luminescent materials

    DOEpatents

    Vardeny, Zeev V.; Jeglinski, Stefan A.; Lane, Paul A.

    2001-01-01

    A radiation detecting device comprising a radiation sensing element, and a layer of luminescent material to expand the range of wavelengths over which the sensing element can efficiently detect radiation. The luminescent material being selected to absorb radiation at selected wavelengths, causing the luminescent material to luminesce, and the luminescent radiation being detected by the sensing element. Radiation sensing elements include photodiodes (singly and in arrays), CCD arrays, IR detectors and photomultiplier tubes. Luminescent materials include polymers, oligomers, copolymers and porphyrines, Luminescent layers include thin films, thicker layers, and liquid polymers.

  17. The nature of unusual luminescence in natural calcite, CaCO3

    SciTech Connect

    Gaft, M.; Nagli, L.; Panczer, G.; Waychunas, G.; Porat, N.

    2008-11-01

    The unusual luminescence of particular varieties of natural pink calcite (CaCO{sub 3}) samples was studied by laser-induced time-resolved luminescence spectroscopy at different temperatures. The luminescence is characterized by intense blue emission under short-wave UV lamp excitation with an extremely long decay time, accompanied by pink-orange luminescence under long wave UV excitation. Our investigation included optical absorption, natural thermostimulated luminescence (NTL) and Laser-Induced Breakdown Spectroscopy (LIBS) studies. Two luminescence centers were detected: a narrow violet band, with {lambda}{sub max} = 412 nm, {Delta} = 45 nm, two decay components of {tau}{sub 1} = 5 ns and {tau}{sub 2} = 7.2 ms, accompanied by very long afterglow, and an orange emission band with {lambda}{sub max} = 595 nm, {Delta} = 90 nm and {tau} = 5 ns. Both luminescence centers are thermally unstable with the blue emission disappearing after heating at 500 C, and the orange emission disappearing after heating at different temperatures starting from 230 C, although sometimes it is stable up to 500 C in different samples. Both centers have spectral-kinetic properties very unusual for mineral luminescence, which in combination with extremely low impurity concentrations, prevent their identification with specific impurity related emission. The most likely explanation of these observations may be the presence of radiation-induced luminescence centers. The long violet afterglow is evidently connected with trapped charge carrier liberation, with their subsequent migration through the valence band and ultimate recombination with a radiation-induced center responsible for the unusual violet luminescence.

  18. Energy dependence measurement of small-type optically stimulated luminescence (OSL) dosimeter by means of characteristic X-rays induced with general diagnostic X-ray equipment.

    PubMed

    Takegami, Kazuki; Hayashi, Hiroaki; Okino, Hiroki; Kimoto, Natsumi; Maehata, Itsumi; Kanazawa, Yuki; Okazaki, Tohru; Hashizume, Takuya; Kobayashi, Ikuo

    2016-01-01

    For X-ray inspections by way of general X-ray equipment, it is important to measure an entrance-skin dose. Recently, a small optically stimulated luminescence (OSL) dosimeter was made commercially available by Landauer, Inc. The dosimeter does not interfere with the medical images; therefore, it is expected to be a convenient detector for measuring personal exposure doses. In an actual clinical situation, it is assumed that X-rays of different energies will be detected by a dosimeter. For evaluation of the exposure dose measured by a dosimeter, it is necessary to know the energy dependence of the dosimeter. Our aim in this study was to measure the energy dependence of the OSL dosimeter experimentally in the diagnostic X-ray region. Metal samples weighing several grams were irradiated and, in this way, characteristic X-rays having energies ranging from 8 to 85 keV were generated. Using these mono-energetic X-rays, the dosimeter was irradiated. Simultaneously, the fluence of the X-rays was determined with a CdTe detector. The energy-dependent efficiency of the dosimeter was derived from the measured value of the dosimeter and the fluence. Moreover, the energy-dependent efficiency was calculated by Monte-Carlo simulation. The efficiency obtained in the experiment was in good agreement with that of the simulation. In conclusion, our proposed method, in which characteristic X-rays are used, is valuable for measurement of the energy dependence of a small OSL dosimeter in the diagnostic X-ray region.

  19. Scanning tunneling luminescence of individual CdSe nanowires.

    PubMed

    Lutz, Theresa; Kabakchiev, Alexander; Dufaux, Thomas; Wolpert, Christian; Wang, Zhe; Burghard, Marko; Kuhnke, Klaus; Kern, Klaus

    2011-08-22

    The local luminescence properties of individual CdSe nanowires composed of segments of zinc blende and wurtzite crystal structures are investigated by low-temperature scanning tunneling luminescence spectroscopy. Light emission from the wires is achieved by the direct injection of holes and electrons, without the need for coupling to tip-induced plasmons in the underlying metal substrate. The photon energy is found to increase with decreasing wire diameter due to exciton confinement. The bulk bandgap extrapolated from the energy versus diameter dependence is consistent with photon emission from the zinc blende-type CdSe sections.

  20. Structural and luminescent properties of electron-irradiated silicon

    SciTech Connect

    Sobolev, N. A.; Loshachenko, A. S.; Aruev, P. N.; Kalyadin, A. E.; Shek, E. I.; Zabrodskiy, V. V.; Shtel'makh, K. F.; Vdovin, V. I.; Xiang, Luelue; Yang, Deren

    2014-02-21

    Structural defects induced by electron irradiation of p-Cz-Si wafers were identified. The influence of the annealing conditions in a chlorine-containing atmosphere on the structural and luminescent properties of the samples was examined. Light-emitting diodes based on electron-irradiated and high-temperature-annealed wafers were fabricated by a vapour-phase epitaxy technique and their luminescence properties were studied. A high-intensity dislocation-related D1 line was observed at 1.6 μm in the room-temperature electroluminescence spectrum.

  1. Luminescent hyperbolic metasurfaces.

    PubMed

    Smalley, J S T; Vallini, F; Montoya, S A; Ferrari, L; Shahin, S; Riley, C T; Kanté, B; Fullerton, E E; Liu, Z; Fainman, Y

    2017-01-09

    When engineered on scales much smaller than the operating wavelength, metal-semiconductor nanostructures exhibit properties unobtainable in nature. Namely, a uniaxial optical metamaterial described by a hyperbolic dispersion relation can simultaneously behave as a reflective metal and an absorptive or emissive semiconductor for electromagnetic waves with orthogonal linear polarization states. Using an unconventional multilayer architecture, we demonstrate luminescent hyperbolic metasurfaces, wherein distributed semiconducting quantum wells display extreme absorption and emission polarization anisotropy. Through normally incident micro-photoluminescence measurements, we observe absorption anisotropies greater than a factor of 10 and degree-of-linear polarization of emission >0.9. We observe the modification of emission spectra and, by incorporating wavelength-scale gratings, show a controlled reduction of polarization anisotropy. We verify hyperbolic dispersion with numerical simulations that model the metasurface as a composite nanoscale structure and according to the effective medium approximation. Finally, we experimentally demonstrate >350% emission intensity enhancement relative to the bare semiconducting quantum wells.

  2. Luminescent hyperbolic metasurfaces

    NASA Astrophysics Data System (ADS)

    Smalley, J. S. T.; Vallini, F.; Montoya, S. A.; Ferrari, L.; Shahin, S.; Riley, C. T.; Kanté, B.; Fullerton, E. E.; Liu, Z.; Fainman, Y.

    2017-01-01

    When engineered on scales much smaller than the operating wavelength, metal-semiconductor nanostructures exhibit properties unobtainable in nature. Namely, a uniaxial optical metamaterial described by a hyperbolic dispersion relation can simultaneously behave as a reflective metal and an absorptive or emissive semiconductor for electromagnetic waves with orthogonal linear polarization states. Using an unconventional multilayer architecture, we demonstrate luminescent hyperbolic metasurfaces, wherein distributed semiconducting quantum wells display extreme absorption and emission polarization anisotropy. Through normally incident micro-photoluminescence measurements, we observe absorption anisotropies greater than a factor of 10 and degree-of-linear polarization of emission >0.9. We observe the modification of emission spectra and, by incorporating wavelength-scale gratings, show a controlled reduction of polarization anisotropy. We verify hyperbolic dispersion with numerical simulations that model the metasurface as a composite nanoscale structure and according to the effective medium approximation. Finally, we experimentally demonstrate >350% emission intensity enhancement relative to the bare semiconducting quantum wells.

  3. Requirements for sulfur in cell density-independent induction of luminescence in Vibrio fischeri under nutrient-starved conditions.

    PubMed

    Tabei, Yosuke; Era, Mariko; Ogawa, Akane; Morita, Hiroshi

    2012-04-01

    Despite the universal requirement for sulfur in living organisms, it is not known whether the luminescence of Vibrio fischeri is sulfur-dependent and how sulfur affects the intensity of its luminescence. In this study, we investigated the requirement for sulfur in V. fischeri luminescence under nutrient-starved conditions. Full induction of V. fischeri luminescence required MgSO(4); in artificial seawater cultures that lacked sufficient MgSO(4), its luminescence was not fully induced. This induction of luminescence was not dependent on autoinduction because the cell density of V. fischeri did not reach the critical threshold concentration. In addition to MgSO(4), this cell density-independent luminescence was induced or maintained by nontoxic concentrations of l-cysteine, sulfate, sulfite, and thiosulfate. Moreover, the addition of N -3-oxo-hexanoyl homoserine lactone and N -octanoyl homoserine lactone, which are known autoinducers in V. fischeri, did not induce luminescence under these conditions. This result suggested that the underlying mechanism of luminescence may be different from the known autoinduction mechanism.

  4. Lanthanide-based luminescence biolabelling.

    PubMed

    Sy, Mohamadou; Nonat, Aline; Hildebrandt, Niko; Charbonnière, Loïc J

    2016-04-14

    Luminescent lanthanide complexes display unrivalled spectroscopic properties, which place them in a special category in the luminescent toolbox. Their long-lived line-like emission spectra are the cornerstones of numerous analytical applications ranging from ultrasensitive homogeneous fluoroimmunoassays to the study of molecular interactions in living cells with multiplexed microscopy. However, achieving such minor miracles is a result of years of synthetic efforts and spectroscopic studies to understand and gather all the necessary requirements for the labels to be efficient. This feature article intends to survey these criteria and to discuss some of the most important examples reported in the literature, before explaining in detail some of the applications of luminescent lanthanide labels to bioanalysis and luminescence microscopy. Finally, the emphasis will be put on some recent applications that hold great potential for future biosensing.

  5. Luminescent solar concentrators: Semiconductor solution

    NASA Astrophysics Data System (ADS)

    Debije, Michael

    2017-03-01

    Reabsorption losses have long been holding back the commercial viability of luminescent solar concentrators. Now, non-toxic silicon-based quantum dots with enhanced Stokes shift may enable the technology to enjoy practical implementation.

  6. Optically stimulated luminescence dosimetry with gypsum wallboard (drywall).

    PubMed

    Thompson, Jeroen W; Burdette, Kevin E; Inrig, Elizabeth L; Dewitt, Regina; Mistry, Rajesh; Rink, W Jack; Boreham, Douglas R

    2010-09-01

    Gypsum wallboard (drywall) represents an attractive target for retrospective dosimetry by optically stimulated luminescence (OSL) in the event of a radiological accident or malicious use of nuclear material. In this study, wallboard is shown to display a radiation-induced luminescence signal (RIS) as well as a natural background signal (NS), which is comparable in intensity to the RIS. Excitation and emission spectra show that maximum luminescence intensity is obtained for stimulation with blue light-emitting diodes (470 nm) and for detection in the ultraviolet region (290-370 nm). It is necessary to decrease the optical stimulation power dramatically in order to adequately separate the RIS from the interfering background signal. The necessary protocols are developed for accurately measuring the absorbed dose as low as 500 mGy and demonstrate that the RIS decays logarithmically with storage time, with complete erasure expected within 1-4 d.

  7. Luminescence flash and temperature determination of the bubble generated by underwater pulsed discharge

    NASA Astrophysics Data System (ADS)

    Zhang, Liancheng; Zhu, Xinlei; Yan, Hui; Huang, Yifan; Liu, Zhen; Yan, Keping

    2017-01-01

    An intense luminescence flash can be induced during the collapse phase of bubbles generated by pulsed discharge in water. To gain insight into this special phenomenon, we experimentally investigated the optical characteristics and luminescence temperature inside collapsing bubbles. The duration of the luminescence flash generated by pulsed discharge was around tens of microseconds, which was confirmed by high-speed recording and the photodiode output, and the inception time of the luminescence flash was approximately 32.5 μs before the bubble collapsed to its minimum size. The temperatures of the luminescence flash at discharge energies of 25 and 30 J/pulse calculated according to the two-line radiance ratio method were 6673 and 6728 K, respectively.

  8. An efficient ionoluminescence analysis of turquoise gemstone as a weakly luminescent mineral.

    PubMed

    Nikbakht, T; Kakuee, O; Lamehi-Rachti, M

    2017-05-15

    The unique ionization pattern of MeV-energy ion beam is applied for efficient luminescence analysis of a collection of natural turquoise samples. The considerable penetration depth of tens of micrometer and enhancement of energy deposition with depth, suggests ionoluminescence as an appropriate technique for studying weakly luminescent minerals. Herein, the luminescence induced in deeper parts of turquoise samples is extracted through their relatively transparent adjacent host stones. The resulting intense spectra reveal the vibrational structure of the broad green luminescence band of turquoise which probably originates from O2(-) centers. Moreover, owing to the applied ionoluminescence approach, red and blue luminescence bands of turquoise were observed which can be ascribed to Fe(3+) ions and UO2(2+) centers respectively. The elemental information of the samples is provided using micro-PIXE analysis technique.

  9. A double substitution induced Ca(Mg0.8, Al0.2)(Si1.8, Al0.2)O6:Eu(2+) phosphor for w-LEDs: synthesis, structure, and luminescence properties.

    PubMed

    Li, Yang; Liu, Wenjing; Wang, Xicheng; Zhu, Ge; Wang, Chuang; Wang, Yuhua

    2015-08-07

    A double substitution induced blue-emitting phosphor Ca(Mg0.8, Al0.2)(Si1.8, Al0.2)O6:Eu(2+) (CMAS:Eu(2+)) was successfully synthesized by a solid-state reaction process, and its structure and luminescence properties were investigated in detail. The crystal structure and chemical composition of the CMAS matrix were analyzed and determined based on Rietveld refinements and Energy Dispersive Spectroscopy (EDS). The composition-optimized CMAS:Eu(2+) exhibited a strong blue light, centered at 446 nm upon excitation at 365 nm with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.144, 0.113). Under 380 nm excitation, the PL emission intensity area of the optimized phosphor was found to be 46.95% of that of the commercial BaMgAl10O17:Eu(2+) (BAM:Eu(2+)) phosphor and the quantum efficiency of the phosphor is 41.32%. The temperature-dependent PL studies have been investigated which show the thermal stability of the CMAS:Eu(2+) phosphor compared with that of the CaMgSi2O6:Eu(2+) (CMS:Eu(2+)) phosphor.

  10. Probing structure-induced optical behavior in a new class of self-activated luminescent 0D/1D CaWO₄ metal oxide – CdSe nanocrystal composite heterostructures

    DOE PAGES

    Han, Jinkyu; McBean, Coray; Wang, Lei; ...

    2015-01-30

    In this report, we synthesize and characterize the structural and optical properties of novel heterostructures composed of (i) semiconducting nanocrystalline CdSe quantum dot (QDs) coupled with (ii) both one and zero-dimensional (1D and 0D) motifs of self-activated luminescence CaWO₄ metal oxides. Specifically, ~4 nm CdSe QDs have been anchored onto (i) high-aspect ratio 1D nanowires, measuring ~230 nm in diameter and ~3 μm in length, as well as onto (ii) crystalline 0D nanoparticles (possessing an average diameter of ~ 80 nm) of CaWO₄ through the mediation of 3-mercaptopropionic acid (MPA) as a connecting linker. Composite formation was confirmed by complementarymore » electron microscopy and spectroscopy (i.e. IR and Raman) data. In terms of luminescent properties, our results show that our 1D and 0D heterostructures evince photoluminescence (PL) quenching and shortened PL lifetimes of CaWO₄ as compared with unbound CaWO₄. We propose that a photo-induced electron transfer process occurs from CaWO₄ to CdSe QDs, a scenario which has been confirmed by NEXAFS measurements and which highlights a decrease in the number of unoccupied orbitals in the conduction bands of CdSe QDs. By contrast, the PL signature and lifetimes of MPA-capped CdSe QDs within these heterostructures do not exhibit noticeable changes as compared with unbound MPA-capped CdSe QDs. The striking difference in optical behavior between CaWO₄ nanostructures and CdSe QDs within our heterostructures can be correlated with the relative positions of their conduction and valence energy band levels. In addition, the PL quenching behaviors for CaWO₄ within the heterostructure configuration were examined by systematically varying (i) the quantities and coverage densities of CdSe QDs as well as (ii) the intrinsic morphology (and by extension, the inherent crystallite size) of CaWO₄ itself.« less

  11. Interactions between bicarbonate, potassium, and magnesium, and sulfur-dependent induction of luminescence in Vibrio fischeri.

    PubMed

    Tabei, Yosuke; Era, Mariko; Ogawa, Akane; Morita, Hiroshi

    2012-06-01

    In spite of its central importance in research efforts, the relationship between seawater compounds and bacterial luminescence has not previously been investigated in detail. Thus, in this study, we investigated the effect of cations (Na(+) , K(+) , NH(4) (+) , Mg(2+) , and Ca(2+) ) and anions (Cl(-) , HCO(3) (-) , CO(3) (2-) , and NO(3) (-) ) on the induction of both inorganic (sulfate, sulfite, and thiosulfate) and organic (L-cysteine and L-cystine) sulfur-dependent luminescence in Vibrio fischeri. We found that HCO(3) (-) (bicarbonate) and CO(3) (2-) (carbonate), in the form of various compounds, had a stimulatory effect on sulfur-dependent luminescence. The luminescence induced by bicarbonate was further promoted by the addition of magnesium. Potassium also increased sulfur-dependent luminescence when sulfate or thiosulfate was supplied as the sole sulfur source, but not when sulfite, L-cysteine, or L-cystine was supplied. The positive effect of potassium was accelerated by the addition of magnesium and/or calcium. Furthermore, the additional supply of magnesium improved the induction of sulfite- or L-cysteine-dependent luminescence, but not the l-cystine-dependent type. These results suggest that sulfur-dependent luminescence of V. fischeri under nutrient-starved conditions is mainly controlled by bicarbonate, carbonate, and potassium. In addition, our results indicate that an additional supply of magnesium is effective for increasing V. fischeri luminescence.

  12. Utilizing Nanofabrication to Construct Strong, Luminescent Materials

    SciTech Connect

    Chen, Wei; Huang, Gang; Lu, Hong B.; McCready, David E.; Joly, Alan G.; Bovin, Jan-Olov

    2006-05-28

    Luminescent materials have been utilized widely in applications from lighting to sensing. The new development of technologies based on luminescence properties requires the materials to have high luminescence efficiency and mechanical strength. In this article, we report the fabrication of luminescent materials possessing high mechanical strength by nanofabrication with polyvinyl alcohol used as a stabilizer or coupling agent. X-ray diffraction and high resolution transmission microscope observations reveal that the nanocomposite sample contains ZnS and ZnO nanoparticles as well as kozoite and sodium nitrate. The mechanical strength and hardness of these nanocomposite materials are higher than polycarbonate and some carbon nanotube reinforced nanocomposites. Strong luminescence is observed in the new nanocomposites and the luminescence intensity does not degrade following up to 30 minutes of X-ray irradiation. Our results indicate that nanofabrication may provide a good method to improve the mechanical strength of luminescent materials for some applications in which high strength luminescent materials are needed.

  13. Turning on the Light: Lessons from Luminescence

    ERIC Educational Resources Information Center

    O'Hara, Patricia B.; Engelson, Carol; St. Peter, Wayne

    2005-01-01

    Some of the processes by which light is emitted without a simultaneous change in temperature are discussed and is classified as luminescence or cold light. Luminescent processes include triboluminescence, fluorescence, phosphorescence, chemiluminescence, and bioluminescence.

  14. Method of measuring luminescence of a material

    SciTech Connect

    Miller, Steven D.

    2015-12-15

    A method of measuring luminescence of a material is disclosed. The method includes applying a light source to excite an exposed material. The method also includes amplifying an emission signal of the material. The method further includes measuring a luminescent emission at a fixed time window of about 10 picoseconds to about 10 nanoseconds. The luminescence may be radio photoluminescence (RPL) or optically stimulated luminescence (OSL).

  15. Direct probing of a polymer electrolyte/luminescent conjugated polymer mixed ionic/electronic conductor.

    PubMed

    Hu, Yufeng; Gao, Jun

    2009-12-30

    What will happen if one brings two metallic probes into direct contact with a polymer film and apply a voltage bias? We demonstrate that, for a mixed ionic/electronic conductor containing a luminescent conjugated polymer and a polymer electrolyte, it is possible to induce strong in situ electrochemical doping of the luminescent polymer and form a dynamic light-emitting p-n junction. Using time-lapse fluorescence imaging, we have visualized p- and n-doping of various shapes and shades, p-n junction electroluminescence, and the effects of voltage reversal. The direct probing technique offers great simplicity and versatility for studying luminescent mixed ionic/electronic conductors.

  16. Specificity of aequorin luminescence to calcium

    NASA Technical Reports Server (NTRS)

    Shimomura, O.; Johnson, F. H.

    1975-01-01

    The presence of Pb(++), Co(++), Cu(++), and Cd(++), each of which possesses a certain luminescence-triggering activity of aequorin, potentially interferes with the specificity of the aequorin luminescence response to Ca(++). Interference by the above cations can be eliminated, without influencing the sensitivity of the luminescence of aequorin to Ca(++), by adding 1 mM of sodium diethyldithiocarbamate.

  17. A luminescent nanocrystal stress gauge

    SciTech Connect

    Choi, Charina; Koski, Kristie; Olson, Andrew; Alivisatos, Paul

    2010-10-25

    Microscale mechanical forces can determine important outcomes ranging from the site of material fracture to stem cell fate. However, local stresses in a vast majority of systems cannot be measured due to the limitations of current techniques. In this work, we present the design and implementation of the CdSe/CdS core/shell tetrapod nanocrystal, a local stress sensor with bright luminescence readout. We calibrate the tetrapod luminescence response to stress, and use the luminescence signal to report the spatial distribution of local stresses in single polyester fibers under uniaxial strain. The bright stress-dependent emission of the tetrapod, its nanoscale size, and its colloidal nature provide a unique tool that may be incorporated into a variety of micromechanical systems including materials and biological samples to quantify local stresses with high spatial resolution.

  18. Decreasing luminescence lifetime of evaporating phosphorescent droplets

    NASA Astrophysics Data System (ADS)

    van der Voort, D. D.; Dam, N. J.; Sweep, A. M.; Kunnen, R. P. J.; van Heijst, G. J. F.; Clercx, H. J. H.; van de Water, W.

    2016-12-01

    Laser-induced phosphorescence has been used extensively to study spray dynamics. It is important to understand the influence of droplet evaporation in the interpretation of such measurements, as it increases luminescence quenching. By suspending a single evaporating n-heptane droplet in an acoustic levitator, the properties of lanthanide-complex europium-thenoyltrifluoroacetone-trioctylphosphine oxide (Eu-TTA-TOPO) phosphorescence are determined through high-speed imaging. A decrease was found in the measured phosphorescence decay coefficient (780 → 200 μs) with decreasing droplet volumes (10-9 → 10-11 m3) corresponding to increasing concentrations (10-4 → 10-2 M). This decrease continues up to the point of shell-formation at supersaturated concentrations. The diminished luminescence is shown not to be attributable to triplet-triplet annihilation, quenching between excited triplet-state molecules. Instead, the pure exponential decays found in the measurements show that a non-phosphorescent quencher, such as free TTA/TOPO, can be attributable to this decay. The concentration dependence of the phosphorescence lifetime can therefore be used as a diagnostic of evaporation in sprays.

  19. Influence of cations and anions on the induction of cell density-independent luminescence in Photorhabdus luminescens.

    PubMed

    Tabei, Yosuke; Ogawa, Akane; Era, Mariko; Ninomiya, Junko; Morita, Hiroshi

    2013-03-01

    Bioluminescence is emitted by various living organisms, including bacteria. While the induction mechanism in marine luminescent bacteria, such as Vibrio fischeri and V. harveyi, has been well characterized, this mechanism has not been studied in detail in the non-marine luminescent bacterium Photorhabdus luminescens. Therefore, we investigated the effect of cations and anions on the induction of luminescence by P. luminescens. Cultivation of cells in an inorganic salts solution (ISS) containing KCl, CaCl2 , MgCl2 , NaHCO3 , and MgSO4 resulted in a rapid increase in luminescence intensity. Moreover, the induction of luminescence in the ISS medium was not dependent on cell density, since cell densities remained unchanged during 48 h. Furthermore, we found that compounds containing K(+) , Mg(2+) , and HCO3(-) were necessary to induce cell density-independent luminescence. The intensity of luminescence per cell cultured in medium containing KCl, MgCl2 , and NaHCO3 was approximately 100-fold higher than that cultured in NB. In contrast, when cells actively grew in normal growth condition, the intensity of luminescence per cell was not increased even in the presence of K(+) , Mg(2+) , and HCO3(-) . Thus, these results suggest that the luminescence of P. luminescens is regulated by 2 independent cell density-dependent and -independent mechanisms.

  20. Luminescence in the fluoride-containing phosphate-based glasses: a possible origin of their high resistance to nanosecond pulse laser-induced damage.

    PubMed

    Wang, Pengfei; Lu, Min; Gao, Fei; Guo, Haitao; Xu, Yantao; Hou, Chaoqi; Zhou, Zhiwei; Peng, Bo

    2015-02-26

    Fusion power offers the prospect of an almost inexhaustible source of energy for future generations. It was reported that fusion fuel gains exceeding unity on the National Ignition Facility (NIF) were achieved, but so far great deal of scientific and engineering challenges have to be overcome for realizing fusion power generation. There is a bottleneck for color-separation gratings in NIF and other similar inertial confinement fusion (ICF) lasers. Here we show a series of high performance phosphate-based glasses that can transmit the third harmonic frequency (3ω) laser light with high efficiency meanwhile filter the fundamental (1ω) and the second harmonic frequency (2ω) laser lights through direct absorption, and especially they exhibit excellent damage threshold induced by nanosecond pulse laser compared with that of the fused silica used in NIF. Yellowish-orange fluorescence emits during the laser-material interaction process, and it can be tailored through regulating the glass structure. Study on its structural origin suggests that the fluorescence emission is a key factor that conduces to the high laser-induced damage resistance of these glasses. The results also indicated the feasibility of utilizing these high performance glasses in novel color separation optics, allowing novel design for the final optics assembly in ICF lasers.

  1. Luminescence in the fluoride-containing phosphate-based glasses: A possible origin of their high resistance to nanosecond pulse laser-induced damage

    NASA Astrophysics Data System (ADS)

    Wang, Pengfei; Lu, Min; Gao, Fei; Guo, Haitao; Xu, Yantao; Hou, Chaoqi; Zhou, Zhiwei; Peng, Bo

    2015-02-01

    Fusion power offers the prospect of an almost inexhaustible source of energy for future generations. It was reported that fusion fuel gains exceeding unity on the National Ignition Facility (NIF) were achieved, but so far great deal of scientific and engineering challenges have to be overcome for realizing fusion power generation. There is a bottleneck for color-separation gratings in NIF and other similar inertial confinement fusion (ICF) lasers. Here we show a series of high performance phosphate-based glasses that can transmit the third harmonic frequency (3ω) laser light with high efficiency meanwhile filter the fundamental (1ω) and the second harmonic frequency (2ω) laser lights through direct absorption, and especially they exhibit excellent damage threshold induced by nanosecond pulse laser compared with that of the fused silica used in NIF. Yellowish-orange fluorescence emits during the laser-material interaction process, and it can be tailored through regulating the glass structure. Study on its structural origin suggests that the fluorescence emission is a key factor that conduces to the high laser-induced damage resistance of these glasses. The results also indicated the feasibility of utilizing these high performance glasses in novel color separation optics, allowing novel design for the final optics assembly in ICF lasers.

  2. pH luminescence switching, dihydrogen phosphate sensing, and cellular uptake of a heterobimetallic ruthenium(II)-rhenium(I) complex.

    PubMed

    Zheng, Ze-Bao; Wu, Yong-Quan; Wang, Ke-Zhi; Li, Fuyou

    2014-02-28

    A new heterobimetallic ruthenium(II)-rhenium(I) complex of [Ru(bpy)2(HL)Re(CO)3Cl](ClO4)2·6H2O (RuHLRe) {bpy = 2,2'-bipyridine and HL = 2-(4-(2,6-di(pyridin-2-yl)pyridin-4-yl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline} was synthesised and characterised by elemental analysis, proton nuclear magnetic resonance spectroscopy, and mass spectrometry. The ground- and excited-state acid-base properties of RuHLRe were studied using UV-Vis absorption spectrophotometric and spectrofluorimetric titrations in a 100 : 1 (v/v) Britton-Robinson buffer-CH3CN solution combined with luminescence lifetime measurements. The complex exhibited two-step separate protonation-deprotonation processes in both the ground and excited states. The complex acted as pH-induced "off-on-off" luminescence switches (I(on)/I(off) = 31.0 and 14.6), with one of the switching actions being driven by pH variations over the physiological pH range (5.3-8.0). Importantly, cellular imaging and cytotoxicity experiments demonstrated that RuHLRe rapidly and selectively illuminated the membrane of HeLa cells over fixed cells and exhibited reduced cytotoxicity at the imaging concentration compared to the Re(I)-free parent Ru(II) complex. In addition, RuHLRe acted as an efficient "turn on" emission sensor for H2PO4(-) and "turn off" emission sensor for F(-) and OAc(-).

  3. Characterisation of gold catalysts.

    PubMed

    Villa, Alberto; Dimitratos, Nikolaos; Chan-Thaw, Carine E; Hammond, Ceri; Veith, Gabriel M; Wang, Di; Manzoli, Maela; Prati, Laura; Hutchings, Graham J

    2016-09-21

    Au-based catalysts have established a new important field of catalysis, revealing specific properties in terms of both high activity and selectivity for many reactions. However, the correlation between the morphology and the activity of the catalyst is not always clear although much effort has been addressed to this task. To some extent the problem relates to the complexity of the characterisation techniques that can be applied to Au catalyst and the broad range of ways in which they can be prepared. Indeed, in many reports only a few characterization techniques have been used to investigate the potential nature of the active sites. The aim of this review is to provide a critical description of the techniques that are most commonly used as well as the more advanced characterization techniques available for this task. The techniques that we discuss are (i) transmission electron microscopy methods, (ii) X-ray spectroscopy techniques, (iii) vibrational spectroscopy techniques and (iv) chemisorption methods. The description is coupled with developing an understanding of a number of preparation methods. In the final section the example of the supported AuPd alloy catalyst is discussed to show how the techniques can gain an understanding of an active oxidation catalyst.

  4. Luminescence in trilanthanumtrichlorotungstate (La 3WO 6Cl 3)

    NASA Astrophysics Data System (ADS)

    Blasse, G.; Dirksen, G. J.; Brixner, L. H.

    1983-03-01

    The luminescence properties of La 3WO 6Cl 3 are reported and discussed. The tungstate group occurs as a trigonal prismatic WO 6-6 complex. The blue luminescence is, for the greater part, quenched at room temperature. No energy migration occurs in this lattice. The decay times are discussed in terms of a simple molecular-orbital (MO) scheme. The luminescence of the following activating ions was studied: Mo 6+, Bi 3+, Eu 3+, Sm 3+, Ce 3+, and Tb 3+. The molybdate group produces a red emission with low efficiency. The Bi 3+ ion induces a narrow band emission with small Stokes shift. This is interpreted using a Bi 3+O 2-W 6+ charge-transfer state. Except for Ce 3+, the rare earth activators show luminescence, but the total transfer efficiency from tungstate to the rare-earth ions is low. This is not due to the one-step tungstate-rare-earth transfer (which is efficient), but to the localized nature of the tungstate excitation. The Eu 3+ charge-transfer band is at very low energies.

  5. Obesity-induced insulin resistance in human skeletal muscle is characterised by defective activation of p42/p44 MAP kinase.

    PubMed

    Ruiz-Alcaraz, Antonio J; Lipina, Christopher; Petrie, John R; Murphy, Michael J; Morris, Andrew D; Sutherland, Calum; Cuthbertson, Daniel J

    2013-01-01

    Insulin resistance (IR), an impaired cellular, tissue and whole body response to insulin, is a major pathophysiological defect of type 2 diabetes mellitus. Although IR is closely associated with obesity, the identity of the molecular defect(s) underlying obesity-induced IR in skeletal muscle remains controversial; reduced post-receptor signalling of the insulin receptor substrate 1 (IRS1) adaptor protein and downstream effectors such as protein kinase B (PKB) have previously been implicated. We examined expression and/or activation of a number of components of the insulin-signalling cascade in skeletal muscle of 22 healthy young men (with body mass index (BMI) range, 20-37 kg/m(2)). Whole body insulin sensitivity (M value) and body composition was determined by the hyperinsulinaemic (40 mU. min(-1).m(-2).), euglycaemic clamp and by dual energy X-ray absorptiometry (DEXA) respectively. Skeletal muscle (vastus lateralis) biopsies were taken before and after one hour of hyperinsulinaemia and the muscle insulin signalling proteins examined by western blot and immunoprecipitation assay. There was a strong inverse relationship between M-value and BMI. The most striking abnormality was significantly reduced insulin-induced activation of p42/44 MAP kinase, measured by specific assay, in the volunteers with poor insulin sensitivity. However, there was no relationship between individuals' BMI or M-value and protein expression/phosphorylation of IRS1, PKB, or p42/44 MAP kinase protein, under basal or hyperinsulinaemic conditions. In the few individuals with poor insulin sensitivity but preserved p42/44 MAP kinase activation, other signalling defects were evident. These findings implicate defective p42/44 MAP kinase signalling as a potential contributor to obesity-related IR in a non-diabetic population, although clearly multiple signalling defects underlie obesity associated IR.

  6. Synergic effects of tryptamine and octopamine on ophiuroid luminescence (Echinodermata).

    PubMed

    Vanderlinden, C; Mallefet, J

    2004-10-01

    In ophiuroids, bioluminescence is under nervous control. Previous studies have shown that acetylcholine is the main neurotransmitter triggering light emission in Amphipholis squamata and Amphiura filiformis. By contrast, none of the neurotransmitters tested so far induced luminescence in two other ophiuroid species, Ophiopsila aranea and Ophiopsila californica. The aim of this work was thus to investigate the putative involvement of two biogenic amines, tryptamine and octopamine, in light emission of three ophiuroid species. A. filiformis responds to both tryptamine and octopamine, mainly on its arm segments, while O. californica only responds to tryptamine stimulation. By contrast, tryptamine and octopamine do not seem to be involved in O. aranea luminescence control since none of these substances induced light emission in this species. The synergic effects of several other drugs with tryptamine and octopamine were also tested.

  7. In-situ luminescence monitoring of ion-induced damage evolution in SiO2 and Al2O3

    DOE PAGES

    Crespillo, Miguel L.; Graham, Joseph T.; Zhang, Yanwen; ...

    2015-12-17

    Real-time, in-situ ionoluminescence measurements provide information of evolution of emission bands with ion fluence, and thereby establish a correlation between point defect kinetics and phase stability. Using fast light ions (2 MeV H and 3.5 He MeV) and medium mass-high energy ions (8 MeV O, E=0.5 MeV/amu), scintillation materials of a-SiO2, crystalline quartz, and Al2O3 are comparatively investigated at room temperature with the aim of obtaining a further insight on the structural defects induced by ion irradiation and understand the role of electronic energy loss on the damage processes. For more energetic heavy ions, the electronic energy deposition pattern offersmore » higher rates of excitation deeper into the material and allows to evaluate the competing mechanisms between the radiative and non-radiative de-excitation processes. Irradiations with 8 MeV O ions have been selected corresponding to the electronic stopping regime, where the electronic stopping power is dominant, and above the critical amorphization threshold for quartz. Lastly, the usefulness of IBIL and its specific capabilities as a sensitive tool to investigate the material characterization and evaluation of radiation effects are demonstrated.« less

  8. The effect of viscosity, applied frequency and driven pressure on the laser induced bubble luminescence in water-sulfuric acid mixtures

    NASA Astrophysics Data System (ADS)

    Sadighi-Bonabi, Rasoul; Alijan Farzad Lahiji, Faezeh; Razeghi, Fatemeh

    2016-06-01

    Production and oscillation of sonoluminescence bubbles by laser pulse in the presence of acoustic field in water and different concentrations of sulfuric acid are investigated. In the presence of acoustic field, the laser causes variable speed of sound, surface tension and density; and the host liquid acts as a compressible one and strongly affects the bubble's dynamics equations. The effect of various concentrations of sulfuric acid as a host liquid on the oscillation of bubble radius, bubble wall velocity and bubble interior temperature is studied. Furthermore, the effect of applied frequency on LI-SCBL in the presence of the acoustic field is investigated and an optimum sound wave frequency for the bubble oscillation and bubble interior temperature in pure water and SA is introduced. Based on the modification of RP equation, by applying the optimum frequency, the results indicate that the maximum bubble radius for LI-SCBL in the presence of the acoustic field is increased up to 7 ×10-4 m as this article presents, which is more than 40% improvement. This amount results in interior temperature of more than three times, from almost 5000 K in the previous works to almost 16 000 K in the present report. This is very similar to the experimental measurements for bubble radius induced by laser. Furthermore, the effects of driving pressure amplitudes on the bubble radius, the bubble interior temperature and the bubble wall velocity in different host liquids and in optimum frequency are investigated.

  9. Electrical characterisation and predictive simulation of defects induced by keV Si{sup +} implantation in n-type Si

    SciTech Connect

    Nyamhere, C.; Cristiano, F.; Olivie, F.; Bedel-Pereira, E.; Essa, Z.; Bolze, D.; Yamamoto, Y.

    2013-05-14

    In this work, we focused on the analysis of implantation-induced defects, mainly small interstitial clusters (ICs) and {l_brace} 311{r_brace} defects introduced in n-type Si after ion implantation using deep level transient spectroscopy (DLTS). Silicon ions (at 160 keV or 190 keV) of fluences ranging from (0.1-8.0) Multiplication-Sign 10{sup 13} cm{sup -2} have been implanted into n-type Si and annealed at temperatures between 500 Degree-Sign C and 800 Degree-Sign C specifically to create small ICs or {l_brace} 311{r_brace} s rod-like defects. In samples dominated by small ICs, DLTS spectra show prominent deep levels at Ec - 0.24 eV and Ec - 0.54 eV. After increasing the fluence and temperature, i.e., reducing the number of small ICs and forming {l_brace} 311{r_brace} defects, the peak Ec - 0.54 eV is still dominant while other electron traps Ec - 0.26 eV and Ec - 0.46 eV are introduced. There were no observable deep levels in reference, non-implanted samples. The identity and origin of all these traps are interpreted in conjunction with recently developed predictive defect simulation models.

  10. Probing the nature of peripheral boryl groups within luminescent tellurophenes.

    PubMed

    Braun, Christina A; Zomerman, Derek; de Aguiar, Inara; Qi, Yanyu; Delgado, William Torres; Ferguson, Michael J; McDonald, Robert; de Souza, Gabriel L C; He, Gang; Brown, Alex; Rivard, Eric

    2017-02-01

    In this article our attempts to tune the color of luminescence within a new class of aggregation-induced emission (AIE) active tellurophenes is reported along with computational details that include spin-orbit coupling effects so as to better understand the nature of emission in the phosphorescent tellurophene (B-Te-6-B). Despite not meeting some of the initial synthetic targets, the emission within a borylated tellurophene can be altered with the addition of an N-heterocyclic carbene.

  11. Luminescence and related properties of nanocrystalline porous silicon

    NASA Astrophysics Data System (ADS)

    Koshida, N.

    This document is part of subvolume C3 'Optical Properties' of volume 34 'Semiconductor quantum structures' of Landolt-Börnstein, Group III, Condensed Matter, on the optical properties of quantum structures based on group IV semiconductors. It discusses luminescence and related properties of nanocrystalline porous silicon. Topics include an overview of nanostructured silicon, its fabrication technology, and properties of nanocrystalline porous silicon such as confinement effects, photoluminescence, electroluminesce, carrier charging effects, ballistic transport and emission, and thermally induced acoustic emission.

  12. Full-Color Tunable Circularly Polarized Luminescent Nanoassemblies of Achiral AIEgens in Confined Chiral Nanotubes.

    PubMed

    Han, Jianlei; You, Jing; Li, Xianggao; Duan, Pengfei; Liu, Minghua

    2017-03-10

    Circularly polarized luminescent (CPL) materials are currently attracting great interest. While a chiral building is usually necessary in order to obtain CPL materials, here, this study proposes a general approach for fabricating 1D circularly polarized luminescent nanoassemblies from achiral aromatic molecules or aggregation-induced emissive compounds (AIEgens). It is found that a C3 symmetric chiral gelator can individually form hexagonal nanotube structures and encapsulate the guest molecules. When achiral AIEgens are encapsulated into the confined nanotubes via organogelation, the AIEgens will emit circularly polarized luminescence. Further, the direction of the CPL could be controlled by the supramolecular chirality of the nanotube. Remarkably, the approach is universal and various kinds of the AIEgens can be doped to show such property, providing a full-color-tunable circularly polarized luminescence.

  13. The sensitized luminescence of manganese-activated calcite

    USGS Publications Warehouse

    Schulman, J.H.; Evans, L.W.; Ginther, R.J.; Murata, K.J.

    1947-01-01

    Synthetic manganese-activated calcites are shown to be practically inert to ultraviolet excitation in the range 2000-3500A, while they are luminescent under cathode-ray excitation. The incorporation of small amounts of an auxiliary impurity along with the manganese produces the strong response to ultraviolet radiation hitherto ascribed to CaCO3:Mn itself. Three such impurities have been studied: lead, thallium, and cerium. The first two induce excitation in the neighborhood of the mercury resonance line, while the cerium introduces a response principally to longer wave ultraviolet. The strong response to 2537A excitation shown by some natural calcites is likewise found to be due to the presence of lead along with the manganese, rather than to the manganese alone. The data do not warrant ascribing the longer wave-length ultraviolet-excited luminescence of all natural calcites to the action of an auxiliary impurity. The essential identity of the cathode-ray excited luminescence spectra of CaCO 3:Mn, CaCO3: (Pb+Mn), CaCO3:(Tl+Mn), and CaCO3:(Ce+Mn) with the 2537A-excited spectra of the latter three is evidence that the luminescent center in all cases is the manganese ion or the MnO6 group. It is shown that a "cascade" mechanism for the action of the auxiliary impurities, lead, thallium, and cerium, is incorrect; and that the phenomenon must be considered as a case of sensitized luminescence. Owing to the nature of cathode-ray excitation, the manganese activator can be excited by this agent even in the absence of a second impurity. For optical excitation, however, an absorption band for the ultraviolet must be established by building into the CaCO3:Mn a second impurity or "sensitizer.".

  14. Dating sediments using luminescence signals

    SciTech Connect

    Wintle, A. )

    1993-05-01

    Before siting a nuclear power station or a nuclear waste repository, it is necessary to establish that the area has been free of earthquake activity for a sufficient period of time. Evidence of past earthquake activity is often provided by faults in surface sediments. Age limits for fault formation can be set by obtaining the depositional ages of the sediment unit in which the fault was formed and the overlying sediment. A useful technique would be one that dating could be applied to the mineral grains that make up the sediments and that would give the time that has passed since the grains were blown or washed into position. Luminescence dating techniques, of which the most well known is thermo-luminescence (TL), provide such information. This approach has been successful in dating movement on the Wasatch Fault in Utah. A combination of TL and radiocarbon dates indicated that three faulting events had occurred within the past 5000 years. 2 refs., 1 fig.

  15. Apparatus for reducing solvent luminescence background emissions

    DOEpatents

    Affleck, Rhett L.; Ambrose, W. Patrick; Demas, James N.; Goodwin, Peter M.; Johnson, Mitchell E.; Keller, Richard A.; Petty, Jeffrey T.; Schecker, Jay A.; Wu, Ming

    1998-01-01

    The detectability of luminescent molecules in solution is enhanced by reducing the background luminescence due to impurity species also present in the solution. A light source that illuminates the solution acts to photolyze the impurities so that the impurities do not luminesce in the fluorescence band of the molecule of interest. Molecules of interest may be carried through the photolysis region in the solution or may be introduced into the solution after the photolysis region.

  16. Apparatus for reducing solvent luminescence background emissions

    DOEpatents

    Affleck, R.L.; Ambrose, W.P.; Demas, J.N.; Goodwin, P.M.; Johnson, M.E.; Keller, R.A.; Petty, J.T.; Schecker, J.A.; Wu, M.

    1998-11-10

    The detectability of luminescent molecules in solution is enhanced by reducing the background luminescence due to impurity species also present in the solution. A light source that illuminates the solution acts to photolyze the impurities so that the impurities do not luminesce in the fluorescence band of the molecule of interest. Molecules of interest may be carried through the photolysis region in the solution or may be introduced into the solution after the photolysis region. 6 figs.

  17. Material for a luminescent solar concentrator

    DOEpatents

    Andrews, L.J.

    1984-01-01

    A material for use in a luminescent solar concentrator, formed by ceramitizing the luminescent ion Cr/sup 3 +/ with a transparent ceramic glass containing mullite. The resultant material has tiny Cr/sup 3 +/-bearing crystallites dispersed uniformly through an amorphous glass. The invention combines the high luminescent efficiency of Cr/sup 3 +/ in the crystalline phase with the practical and economical advantages of glass technology.

  18. Luminescent barometry in wind tunnels

    NASA Technical Reports Server (NTRS)

    Kavandi, Janet; Callis, James; Gouterman, Martin; Khalil, Gamal; Wright, Daniel; Green, Edmond; Burns, David; Mclachlan, Blair

    1990-01-01

    A flexible and relatively inexpensive method and apparatus are described for continuous pressure mapping of aerodynamic surfaces using photoluminescence and imaging techniques. Platinum octaethylporphyrin (PtOEP) has a phosphorescence known to be quenched by oxygen. When dissolved in a silicone matrix, PtOEP may be distributed over a surface as a thin, uniform film. When the film is irradiated with ultraviolet light, the luminescence intensity provides a readily detectable, qualitative surface flow visualization. Moreover, since the luminescence intensity is found to be inversely proportional to the partial pressure of oxygen, a quantitative measure of pressure change may be obtained using a silicon target vidicon or a charge-coupled device video sensor to measure intensity. Luminescent images are captured by a commercial frame buffer board. Images taken in wind tunnels during airflow are ratioed to images taken under ambient 'wind-off' conditions. The resulting intensity ratio information is converted to pressure using calibration curves of I0/I vs p/p0, where I0 is the intensity at ambient pressure p0 and I is the intensity at any other pressure p.

  19. Luminescent detection of hydrazine and hydrazine derivatives

    DOEpatents

    Swager, Timothy M [Newton, MA; Thomas, III, Samuel W.

    2012-04-17

    The present invention generally relates to methods for modulating the optical properties of a luminescent polymer via interaction with a species (e.g., an analyte). In some cases, the present invention provides methods for determination of an analyte by monitoring a change in an optical signal of a luminescent polymer upon exposure to an analyte. Methods of the present invention may be useful for the vapor phase detection of analytes such as explosives and toxins. The present invention also provides methods for increasing the luminescence intensity of a polymer, such as a polymer that has been photobleached, by exposing the luminescent polymer to a species such as a reducing agent.

  20. Resonance-shifting luminescent solar concentrators

    DOEpatents

    Giebink, Noel Christopher; Wiederrecht, Gary P; Wasielewski, Michael R

    2014-09-23

    An optical system and method to overcome luminescent solar concentrator inefficiencies by resonance-shifting, in which sharply directed emission from a bi-layer cavity into a glass substrate returns to interact with the cavity off-resonance at each subsequent reflection, significantly reducing reabsorption loss en route to the edges. In one embodiment, the system comprises a luminescent solar concentrator comprising a transparent substrate, a luminescent film having a variable thickness; and a low refractive index layer disposed between the transparent substrate and the luminescent film.

  1. Luminescence properties of a Fibonacci photonic quasicrystal.

    PubMed

    Passias, V; Valappil, N V; Shi, Z; Deych, L; Lisyansky, A A; Menon, V M

    2009-04-13

    An active one-dimensional Fibonacci photonic quasi-crystal is realized via spin coating. Luminescence properties of an organic dye embedded in the quasi-crystal are studied experimentally and compared to theoretical simulations. The luminescence occurs via the pseudo-bandedge mode and follows the dispersion properties of the Fibonacci crystal. Time resolved luminescence measurement of the active structure shows faster spontaneous emission rate, indicating the effect of the large photon densities available at the bandedge due to the presence of critically localized states. The experimental results are in good agreement with the theoretical calculations for steady-state luminescence spectra.

  2. Energy Transfer and Luminescence in Manganese - Crystals.

    NASA Astrophysics Data System (ADS)

    Danko, Joseph John

    An investigation, directed toward an understanding of the concentration-dependent characteristics of the Mn -Mn energy transfer, has been carried out in RbMn(,x)Mg(,1 -x)F(,3) via a detailed luminescence study in the temperature range, 4-120K. The emission of RbMn(,x)Mg(,1-x)F(,3), down to a concentration of 40% Mn, consists of two distinct Mn bands which are featureless except in the case of the stoichiometric system. The dominant sharp-line structure of this latter system spans the spectral range, 5515-5960(ANGSTROM), and is found to exhibit multi-magnon characteristics. The emission bands of RbMn(,x)Mg(,1-x)F(,3) are attributed to phonon-assisted transitions from two impurity-induced Mn traps. The variations of spectra and of the decay patterns with temperature are used to model the deexcitation mechanism in RbMn(,x)Mg(,1-x)F(,3) and result in the determination of the rate of energy transfer to the shallow luminescence trap. This work is prefaced by an introduction to the theory of collective electronic and magnetic excitations and by a comprehensive review of the various electronic, magnetic and optical properties of stoichiometric Mn-based crystals. As a secondary research effort, the 10488(ANGSTROM) line of Nd in RbMnF(,3):Nd was studied as a function of temperature. The strength of such a line is a direct consequence of the ability of Mn to efficiently transfer its excitation to the Nd centers. The lineshift with change in temperature is due to the continual absorption and emission of virtual phonons; the thermal line broadening is due to a Raman scattering of phonons.

  3. Optical and luminescence studies of ZnMoO 4 using vacuum ultraviolet synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Mikhailik, V. B.; Kraus, H.; Wahl, D.; Ehrenberg, H.; Mykhaylyk, M. S.

    2006-06-01

    In this paper we present a characterisation of ZnMoO 4 using spectroscopic techniques. Reflection, luminescence and luminescence excitation spectra were measured over the temperature range 8-295 K using VUV synchrotron radiation. The emission spectrum of the crystal exhibits a broad band with a maximum around 1.95 eV at 80 K that is attributed to the radiative transitions within MO 42- oxyanion complex. An interpretation of the observed features of the electronic excitations in the crystal is given based on present knowledge of the electronic structure and emission properties of molybdate crystals. The results of this study suggest that ZnMoO 4 is a suitable candidate for further testing for implementation as a target material in cryogenic scintillation searches for rare events.

  4. Thumb Imprint Based Detection of Hyperbilirubinemia Using Luminescent Gold Nanoclusters

    PubMed Central

    Basu, Srestha; Sahoo, Amaresh Kumar; Paul, Anumita; Chattopadhyay, Arun

    2016-01-01

    Early and easy detection of diseases, using point-of-care and inexpensive devices, not only provides option for early treatment but also reduces the risk of propagation. Herein we report the fabrication of a robust film based luminescence indicator of bilirubin, which can indicate hyperbilirubinemia through the thumb imprint of the patient. The UV-light induced luminescence intensity of the film, made out of chitosan stabilised gold (Au) nanoclusters, which was effectively quenched in the presence of Cu2+ ions, recovered in the presence of bilirubin from skin or blood serum. Moreover, the sensitivity of detection of bilirubin was tuneable with the amount of Cu2+ added, thereby facilitating the detection of the desired concentration range of bilirubin. PMID:27976728

  5. Thumb Imprint Based Detection of Hyperbilirubinemia Using Luminescent Gold Nanoclusters

    NASA Astrophysics Data System (ADS)

    Basu, Srestha; Sahoo, Amaresh Kumar; Paul, Anumita; Chattopadhyay, Arun

    2016-12-01

    Early and easy detection of diseases, using point-of-care and inexpensive devices, not only provides option for early treatment but also reduces the risk of propagation. Herein we report the fabrication of a robust film based luminescence indicator of bilirubin, which can indicate hyperbilirubinemia through the thumb imprint of the patient. The UV-light induced luminescence intensity of the film, made out of chitosan stabilised gold (Au) nanoclusters, which was effectively quenched in the presence of Cu2+ ions, recovered in the presence of bilirubin from skin or blood serum. Moreover, the sensitivity of detection of bilirubin was tuneable with the amount of Cu2+ added, thereby facilitating the detection of the desired concentration range of bilirubin.

  6. Solid-state luminescence for the optical examination of archaeological glass beads

    NASA Astrophysics Data System (ADS)

    Zacharias, N.; Beltsios, K.; Oikonomou, A.; Karydas, A. G.; Bassiakos, Y.; Michael, C. T.; Zarkadas, Ch.

    2008-03-01

    The work pertains to the application of solid-state luminescence as a characterization tool for glassy ceramic cultural artefacts. An archaeological glass bead collection excavated at the city of Thebes, Greece and considered as unique in terms of typological variety and time span was examined with the application of luminescence techniques (thermoluminescence, optically stimulated luminescence). Additionally, X-rays fluorescence (XRF) was used to provide non-destructively the elemental concentration profile of the samples. The thermoluminescence signals following laboratory irradiation provided distinct groups of spectra types according to the color classification of the samples. For each sample, the signal sensitivity and growth were examined using both thermoluminescence and optically stimulated luminescence recording. The study provides evidence for the usefulness of the combined application of luminescence and non-destructive, XRF-based, elemental analysis for the characterization of glass assemblages. Finally, due to the satisfactory level of radiation-induced signal intensity, the work suggests the possibility of chronological estimation of ancient glass beads using luminescence dating protocols.

  7. Hexagonal boron nitride luminescence dependent on vacuum level and surrounding gases

    SciTech Connect

    Korsaks, V.

    2015-10-15

    Highlights: • 400 nm Luminescence of hBN powder is sensitive to surrounding vacuum or oxygen gas. • Decrease of hBN powder grain size improves its oxygen sensing properties. • hBN powder is proposed as prospective material for oxygen gas sensors. - Abstract: Gas sensing properties of hBN powder bulk and nanosize were studied. It was demonstrated that for hBN powders with grain sizes of 70 nm, 1 μm and 5 μm the native defect-induced luminescence observed at 400 nm under 265 nm light excitation and room temperature is sensitive to oxygen gas reducing luminescence intensity. The highest value of luminescence intensity is reached when sample is in vacuum. Results obtained allow conclusion that the hBN powder is prospective for sensing of oxygen gas. Some material properties such as dependence of luminescence intensity on vacuum level and pumping time, ratio of luminescence intensity when sample is in vacuum and gas, its dependence on material grain size were studied.

  8. Structural Organization of {pi} Conjugated Highly Luminescent Molecular Material

    SciTech Connect

    Toudic, B.; Limelette, P.; Le Gac, F.; Moreac, A.; Rabiller, P.; Froyer, G.

    2005-11-18

    We report on striking evidence for a room temperature structural phase instability in p-hexaphenyl, inducing a nonplanar conformation of the molecules. Solid state proton NMR and single crystal x-ray diffraction allow the analysis of the organization, the individual dynamics and the involved symmetry breaking. The analysis of Raman spectra above and below room temperature reveals a singular behavior suggesting a modification of the overlap between the electronic wave function induced by the nonplanarity. These results provide a new basis to answer fundamental issues related to molecular and electronic materials and, in particular, luminescent organic devices.

  9. Spectral Characterization of a Novel Luminescent Organogel

    ERIC Educational Resources Information Center

    Waguespack, Yan; White, Shawn R.

    2007-01-01

    The spectroscopic-based luminescence experiments were designed to expose the students to various concepts of single-triplet excited states, electron spin, vibrational relaxation, fluorescence-phosphorescence lifetimes and quenching. The students were able to learn about luminescence spectra of the gel and have the experience of synthesizing a…

  10. Luminescence of thermally altered human skeletal remains.

    PubMed

    Krap, Tristan; Nota, Kevin; Wilk, Leah S; van de Goot, Franklin R W; Ruijter, Jan M; Duijst, Wilma; Oostra, Roelof-Jan

    2017-02-23

    Literature on luminescent properties of thermally altered human remains is scarce and contradictory. Therefore, the luminescence of heated bone was systemically reinvestigated. A heating experiment was conducted on fresh human bone, in two different media, and cremated human remains were recovered from a modern crematory. Luminescence was excited with light sources within the range of 350 to 560 nm. The excitation light was filtered out by using different long pass filters, and the luminescence was analysed by means of a scoring method. The results show that temperature, duration and surrounding medium determine the observed emission intensity and bandwidth. It is concluded that the luminescent characteristic of bone can be useful for identifying thermally altered human remains in a difficult context as well as yield information on the perimortem and postmortem events.

  11. Luminescent gold nanoparticles for bioimaging

    NASA Astrophysics Data System (ADS)

    Zhou, Chen

    Inorganic nanoparticles (NPs) with tunable and diverse material properties hold great potential as contrast agents for better disease management. Over the past decades, luminescent gold nanoparticles (AuNPs) with intrinsic emissions ranging from the visible to the near infrared have been synthesized and emerge as a new class of fluorophores for bioimaging. This dissertation aims to fundamentally understand the structure-property relationships in luminescent AuNPs and apply them as contrast agents to address some critical challenges in bioimaging at both the in vitro and in vivo level. In Chapter 2, we described the synthesized ~20 nm polycrystalline AuNPs (pAuNPs), which successfully integrated and enhanced plasmonic and fluorescence properties into a single AuNP through the grain size effect. The combination of these properties in one NP enabled AuNPs to serve as a multimodal contrast agent for in vitro optical microscopic imaging, making it possible to develop correlative microscopic imaging techniques. In Chapters 3-5, we proposed a feasible approach to optimize the in vivo kinetics and clearance profile of nanoprobes for multimodality in vivo bioimaging applications by using straightforward surface chemistry with luminescent AuNPs as a model. Luminescent glutathione-coated AuNPs of ~2 nm were synthesized. Investigation of the biodistribution showed that these glutathione-coated AuNPs (GS-AuNPs) exhibit stealthiness to the reticuloendothelial system (RES) organs and efficient renal clearance, with only 3.7+/-1.9% and 0.3+/-0.1% accumulating in the liver and spleen, and over 65% of the injection dose cleared out via the urine within the first 72 hours. In addition, ~2.5 nm NIR-emitting radioactive glutathione-coated [198Au]AuNPs (GS-[198Au]AuNPs) were synthesized for further evaluation of the pharmacokinetic profile of GS-AuNPs and potential multimodal imaging. The results showed that the GS-[198Au]AuNPs behave like small-molecule contrast agents in

  12. Mechanically driven luminescence in a ZnS:Cu-PDMS composite

    NASA Astrophysics Data System (ADS)

    Sohn, Kee-Sun; Timilsina, Suman; Singh, Satendra Pal; Choi, Taekjib; Kim, Ji Sik

    2016-10-01

    The conventional mechanoluminescence (ML) mechanism of phosphors such as SrAl2O4:Eu and ZnS:Mn is known to utilize carrier trapping at shallow traps followed by stress (or strain)-induced detrapping, which leads to activator recombination in association with local piezoelectric fields. However, such a conventional ML mechanism was found to be invalid for the ZnS:Cu-embedded polydimethylsiloxane (PDMS) composite, due to the absence of luminescence with a rigid matrix and a negligibly small value of the piezoelectric coefficient (d33) of the composite. An alternative mechanism, namely, the triboelectricity-induced luminescence has been proposed for the mechanically driven luminescence of a ZnS:Cu-PDMS composite.

  13. BRITICE-CHRONO: Constraining retreat of the last British-Irish Ice Sheet using luminescence geochronometry

    NASA Astrophysics Data System (ADS)

    Duller, Geoff; Smedley, Rachel; Bateman, Mark; Medialdea, Alicia; Chiverrell, Richard; Fabel, Derek; Clark, Chris; Consortium, Britice-Chrono

    2016-04-01

    The BRITICE-CHRONO project funded by NERC is a multi-million pound consortium designed to use multiple geochronometers to constrain the rate of retreat of the major outlets of the last British-Irish Ice Sheet (BIIS) at the end of the last glacial cycle. Cosmogenic isotopes, radiocarbon and luminescence dating methods are being applied to materials sampled along lines of ice retreat. Luminescence dating for this project has targeted glaciofluvial sediments associated with ice retreat and over 150 samples from around the British Isles have been analysed in two laboratories. All samples have been analysed using small aliquot or single grain measurements of quartz optically stimulated luminescence (OSL). The resulting dose distributions have been modelled to obtain the depositional age. The major challenges in the application of quartz OSL can be grouped into two categories: signal characteristics and statistical characterisation of dose distributions. Samples have been collected over the entire British Isles and have very variable characteristics. Some samples give bright OSL signals, whilst in other areas the quartz is dim. A pervasive problem is the occurrence of grains which appear to be quartz but which are sensitive to infrared stimulation. Effective screening of these grains is essential to avoid dose underestimation. The second challenge has been estimating appropriate numerical parameters for application of minimum age models. Extensive dose recovery experiments have been undertaken to form the basis for estimates of overdispersion, and in some areas these show highly variable luminescence characteristics. The reproducibility of the analyses undertaken has been assessed through an intercomparison between the two luminescence laboratories and the results of this exercise will be discussed.

  14. Luminescence and radiation resistance of undoped NaI crystals

    SciTech Connect

    Shiran, N. Boiaryntseva, I.; Gektin, A.; Gridin, S.; Shlyakhturov, V.; Vasuykov, S.

    2014-11-15

    Highlights: • The performance of NaI scintillators depends on luminescence properties. • A criterion of crystals’ purity level is radiation colorability at room temperature. • The traces of the most dangerous impurities were detected. • Crucial role in efficiency of pure NaI scintillator play the crystal perfection. - Abstract: Undoped NaI single crystal is an excellent scintillator at low temperature. However, scintillation parameters of different quality crystals vary in a wide range, significantly exceeding measurement error. Experimental data demonstrate the features of luminescence, radiation induced coloration, and afterglow dependence on the quality of nominally pure crystals. It is found that defects level that allows to elucidate artefacts introduced by traces of harmful impurities corresponds to 3 × 10{sup 15} cm{sup −3} that significantly overhead accuracy of chemical and absorption analysis. It is shown that special raw material treatment before and during the single crystal growth allows to reach NaI purity level that avoids impurities influence to the basic luminescence data.

  15. Visible luminescence studies in the infrared multiphoton dissociation of 1,2-dichloro-1,1-difluoroethane

    NASA Astrophysics Data System (ADS)

    Pushpa, K. K.; Kumar, Awadesh; Naik, P. D.; Annaji Rao, K.; Parthasarathy, V.; Sarkar, S. K.; Mittal, J. P.

    1997-11-01

    A strong visible luminescence was observed in the CO 2 laser induced infrared multiphoton dissociation of 1,2-dichloro-1,1-difluoroethane. The emission observed between 350-750 nm is attributed to electronically excited carbene CF 2ClCH. The temporal profile of this luminescence was studied as a function of laser pulse duration, pulse energy, excitation frequency and substrate pressure. A suitable dissociation mechanism is presented considering various channels of IRMPD of this molecule.

  16. Uranocircite: luminescence and crystal structure

    SciTech Connect

    Matkovskiy, A.O.; Sidorenko, G.A.; Tarashchan, A.N.

    1981-01-01

    A study on the determination of the complex structure of the electron-vibration spectra and the elucidation of their relation to crystallochemical factors in uranocircite is presented. The work was performed on samples from zones of a single crystal of the same natural meta-uranocircite, differing in color, and also on other specimens from various Soviet and foreign deposits. Of the 15 meta-uranocircite specimens investigated, in 14 cases the luminescence spectra were homoypic and were a series of equidistant groups of lines of the fine structure; the spectral position of which was practically constant for all the specimens. The degree of hydration was found to have practically no influence on the luminescence of the meta-uranocircite. The investigation supports the supposition that there are marked differences in the structures of minerals of the uran-mica group, although in the authors' opinion, the mechanism itself of multi-center radiation is universal and manifested for all secondary uranium minerals. (JMT)

  17. Novel dental dynamic depth profilometric imaging using simultaneous frequency-domain infrared photothermal radiometry and laser luminescence

    NASA Astrophysics Data System (ADS)

    Nicolaides, Lena; Mandelis, Andreas

    2000-01-01

    A high-spatial-resolution dynamic experimental imaging setup, which can provide simultaneous measurements of laser- induced frequency-domain infrared photothermal radiometric and luminescence signals from defects in teeth, has been developed for the first time. The major findings of this work are: (1) radiometric images are complementary to (anticorrelated with) luminescence images, as a result of the nature of the two physical signal generation processes; (2) the radiometric amplitude exhibits much superior dynamic (signal resolution) range to luminescence in distinguishing between intact and cracked sub-surface structures in the enamel; (3) the radiometric signal (amplitude and phase) produces dental images with much better defect localization, delineation, and resolution; (4) radiometric images (amplitude and phase) at a fixed modulation frequency are depth profilometric, whereas luminescence images are not; and (5) luminescence frequency responses from enamel and hydroxyapatite exhibit two relaxation lifetimes, the longer of which (approximately ms) is common to all and is not sensitive to the defect state and overall quality of the enamel. Simultaneous radiometric and luminescence frequency scans for the purpose of depth profiling were performed and a quantitative theoretical two-lifetime rate model of dental luminescence was advanced.

  18. Luminescent spectroscopy of dry tailings urine

    NASA Astrophysics Data System (ADS)

    Bilyi, Olexander; Bordun, Oleg; Yarynovska, Ivanna

    2006-05-01

    In the work the results of research of luminescent spectrums by photo excitation in the interval of waves lengths 250 - 550 nm and ofluminescent spectrums by the nitric laser (337,1 mn) excitation ofdiy tailings urinaryby the temperature of 300 °K are represented. In the spectral interval of 400 - 800 nm a wide bar of luminescence, intensity of which depends on the type of excitation. was observed. It is set, that presence of salts with oxalate, urate and phosphatic compositions in urine results in the move of maximum of luniinescent spectrums in the long-wave region of spectrum and changes the intensity of luminescence. The possible mechanisms of the observed changes in the spectrums of luminescence of dry urine tailings are examined in the work. The model of recombrnational processes which describe the looked luminescent processes is offered. Possible explanations of the looked features in the spectrums of luminescence combine with luminescence of nanobiological complexes, inorganic salts, urea and natural proteins enter in composition of which.

  19. Thermomechanical characterisation of cellular rubber

    NASA Astrophysics Data System (ADS)

    Seibert, H.; Scheffer, T.; Diebels, S.

    2016-09-01

    This contribution discusses an experimental possibility to characterise a cellular rubber in terms of the influence of multiaxiality, rate dependency under environmental temperature and its behaviour under hydrostatic pressure. In this context, a mixed open and closed cell rubber based on an ethylene propylene diene monomer is investigated exemplarily. The present article intends to give a general idea of the characterisation method and the considerable effects of this special type of material. The main focus lies on the experimental procedure and the used testing devices in combination with the analysis methods such as true three-dimensional digital image correlation. The structural compressibility is taken into account by an approach for a material model using the Theory of Porous Media with additional temperature dependence.

  20. Characterisation of a track structure imaging detector.

    PubMed

    Casiraghi, M; Bashkirov, V A; Hurley, R F; Schulte, R W

    2015-09-01

    The spatial distribution of radiation-induced ionisations in sub-cellular structures plays an important role in the initial formation of radiation damage to biological tissues. Using the nanodosimetry approach, physical characteristics of the track structure can be measured and correlated to DNA damage. In this work, a novel nanodosimeter is presented, which detects positive ions produced by radiation interacting with a gas-sensitive volume in order to obtain a high resolution image of the radiation track structure. The characterisation of the detector prototype was performed and different configurations of the device were tested by varying the detector cathode material and the working gas. Preliminary results show that the ionisation cluster size distribution can be obtained with this approach. Further work is planned to improve the detector efficiency in order to register the complete three-dimensional track structure of ionising radiation.

  1. Characterisation of senescence-induced changes in light harvesting complex II and photosystem I complex of thylakoids of Cucumis sativus cotyledons: age induced association of LHCII with photosystem I.

    PubMed

    Prakash, Jogadhenu Syama Sundara; Baig, Masroor A; Bhagwat, Anil S; Mohanty, Prasanna

    2003-02-01

    Structure and function of chloroplasts are known to after during senescence. The senescence-induced specific changes in light harvesting antenna of photosystem II (PSII) and photosystem I (PSI) were investigated in Cucumis cotyledons. Purified light harvesting complex II (LHCII) and photosystem I complex were isolated from 6-day non-senescing and 27-day senescing Cucumis cotyledons. The chlorophyll a/b ratio of LHCII obtained from 6-day-old control cotyledons and their absorption, chlorophyll a fluorescence emission and the circular dichroism (CD) spectral properties were comparable to the LHCII preparations from other plants such as pea and spinach. The purified LHCII obtained from 27-day senescing cotyledons had a Chl a/b ratio of 1.25 instead of 1.2 as with 6-day LHCII and also exhibited significant changes in the visible CD spectrum compared to that of 6-day LHCII, indicating some specific alterations in the organisation of chlorophylls of LHCII. The light harvesting antenna of photosystems are likely to be altered due to aging. The room temperature absorption spectrum of LHCII obtained from 27-day senescing cotyledons showed changes in the peak positions. Similarly, comparison of 77K chlorophyll a fluorescence emission characteristics of LHCII preparation from senescing cotyledons with that of control showed a small shift in the peak position and the alteration in the emission profile, which is suggestive of possible changes in energy transfer within LHCII chlorophylls. Further, the salt induced aggregation of LHCII samples was lower, resulting in lower yields of LHCII from 27-day cotyledons than from normal cotyledons. Moreover, the PSI preparations of 6-day cotyledons showed Chl a/b ratios of 5 to 5.5, where as the PSI sample of 27-day cotyledons had a Chl a/b ratio of 2.9 suggesting LHCII association with PSI. The absorption, fluorescence emission and visible CD spectral measurements as well as the polypeptide profiles of 27-day cotyledon-PSI complexes

  2. Controlled growth, intense upconversion emissions and concentration induced luminescence switching of bifunctional Tm(3+) doped hexagonal NaYb0.55Gd0.45F4 nanorods.

    PubMed

    Qu, Xilong; Li, Yongchang; Yu, Suixi; Yang, Liwen

    2013-11-01

    Bifunctional hexagonal Tm(3+) doped NaYb0.55Gd0.45F4 nanorods with tunable size are prepared via in situ cation-exchange reaction using hydrothermal method. The measured field dependence of magnetization of the NaYb0.55Gd0.45F4 nanorods shows typical paramagnetic characteristics that can be ascribed to the non-interacting localized nature of the magnetic moment of rare-earth ions. When excited by a 980nm laser, these nanorods exhibit intense multi-color up-conversion (UC) emissions in infrared, red, blue and especially ultraviolet. In addition, luminescent switching between different UC emission wavelengths of 480nm and 450nm is observed by adjusting Tm(3+) doping concentration. Based on power-dependent spectral analyses, it is found that with the increase of Tm(3+) doping concentration, due to the suppressed saturation effect, the dominative UC process redistribute the populations at (1)G4 and (1)D2(Tm(3+)) states of Tm(3+) ion resulting in the above luminescent switching. Our results indicate that bifunctional hexagonal NaYb1-xGdxF4 nanocrystals have potential applications in miniaturized solid-state light sources, optical processing sensors and fluorescent biolabels.

  3. Controlled growth, intense upconversion emissions and concentration induced luminescence switching of bifunctional Tm3+ doped hexagonal NaYb0.55Gd0.45F4 nanorods

    NASA Astrophysics Data System (ADS)

    Qu, Xilong; Li, Yongchang; Yu, Suixi; Yang, Liwen

    2013-11-01

    Bifunctional hexagonal Tm3+ doped NaYb0.55Gd0.45F4 nanorods with tunable size are prepared via in situ cation-exchange reaction using hydrothermal method. The measured field dependence of magnetization of the NaYb0.55Gd0.45F4 nanorods shows typical paramagnetic characteristics that can be ascribed to the non-interacting localized nature of the magnetic moment of rare-earth ions. When excited by a 980 nm laser, these nanorods exhibit intense multi-color up-conversion (UC) emissions in infrared, red, blue and especially ultraviolet. In addition, luminescent switching between different UC emission wavelengths of 480 nm and 450 nm is observed by adjusting Tm3+ doping concentration. Based on power-dependent spectral analyses, it is found that with the increase of Tm3+ doping concentration, due to the suppressed saturation effect, the dominative UC process redistribute the populations at 1G4 and 1D2(Tm3+) states of Tm3+ ion resulting in the above luminescent switching. Our results indicate that bifunctional hexagonal NaYb1-xGdxF4 nanocrystals have potential applications in miniaturized solid-state light sources, optical processing sensors and fluorescent biolabels.

  4. Optical absorption and luminescence in neutron-irradiated, silica-based fibers

    SciTech Connect

    Cooke, D.W.; Farnum, E.H.; Clinard, F.W.

    1995-04-01

    The objectives of this work are to assess the effects of thermal annealing and photobleaching on the optical absorption of neutron-irradiated, silica fibers of the type proposed for use in ITER diagnostics, and to measure x-ray induced luminescence of unirradiated (virgin) and neutron-irradiated fibers.

  5. Circularly Polarized Luminescence from Helically Chiral N,N,O,O-Boron-Chelated Dipyrromethenes.

    PubMed

    Alnoman, Rua B; Rihn, Sandra; O'Connor, Daniel C; Black, Fiona A; Costello, Bernard; Waddell, Paul G; Clegg, William; Peacock, Robert D; Herrebout, Wouter; Knight, Julian G; Hall, Michael J

    2016-01-04

    Helically chiral N,N,O,O-boron chelated dipyrromethenes showed solution-phase circularly polarized luminescence (CPL) in the red region of the visible spectrum (λem (max) from 621 to 663 nm). The parent dipyrromethene is desymmetrised through O chelation of boron by the 3,5-ortho-phenolic substituents, inducing a helical chirality in the fluorophore. The combination of high luminescence dissymmetry factors (|glum | up to 4.7 ×10(-3) ) and fluorescence quantum yields (ΦF up to 0.73) gave exceptionally efficient circularly polarized red emission from these simple small organic fluorophores, enabling future application in CPL-based bioimaging.

  6. Luminescence in quantum-confined cadmium selenide nanocrystals and nanorods in external electric fields

    SciTech Connect

    Gurinovich, L. I. Lutich, A. A.; Stupak, A. P.; Prislopsky, S. Ya.; Rusakov, E. K.; Artemyev, M. V.; Gaponenko, S. V.; Demir, H. V.

    2009-08-15

    It is found that the absorption and luminescence spectra of CdSe nanocrystals and nanorods depend on the external electric field. It is shown that the external electric field quenches the P-polarized photoluminescence of CdSe nanorods to a degree higher than the degree of field-induced quenching of the S-polarized photoluminescence. It is established that the nanocrystals are more sensitive to the external electric field than the nanorods. The effect of the external electric field on the luminescence properties of the semiconductor nanorods is discussed.

  7. Cell probing by delayed luminescence

    NASA Astrophysics Data System (ADS)

    Musumeci, Francesco; Ballerini, Monica; Baroni, Giuliana; Costato, Michele; Ferraro, Lorenzo; Milani, Marziale; Scordino, Agata; Triglia, Antonio

    1999-05-01

    Delayed luminescence (D.L.) is a measure that provides important information on biological systems fields, structures and activities, by counting impinging and emitted photons. Many recent experimental works have shown the existence of a close connection, sometimes analytically expressed between the biological state of the system and D.L. parameters. Our investigations aim to show that D.L. is a workable analytical technique covering a large number of disciplinary fields, from agriculture to pollution control and from medical diagnostics to food quality control. The authors have conducted systematic research about D.L. from unicellular alga Acetabularia acetabulum to Saccharomyces cerevisiae yeast cultures and about more complex systems such as Soya seed (Glycine max, L.) and its dependence on sample preparation, history, intracellular signaling, metabolism and pollutant presence. We will discuss the most relevant results together with theoretical considerations on the basic interaction at work between biological systems and electromagnetic fields.

  8. Nanocrystals for luminescent solar concentrators.

    PubMed

    Bradshaw, Liam R; Knowles, Kathryn E; McDowall, Stephen; Gamelin, Daniel R

    2015-02-11

    Luminescent solar concentrators (LSCs) harvest sunlight over large areas and concentrate this energy onto photovoltaics or for other uses by transporting photons through macroscopic waveguides. Although attractive for lowering solar energy costs, LSCs remain severely limited by luminophore reabsorption losses. Here, we report a quantitative comparison of four types of nanocrystal (NC) phosphors recently proposed to minimize reabsorption in large-scale LSCs: two nanocrystal heterostructures and two doped nanocrystals. Experimental and numerical analyses both show that even the small core absorption of the leading NC heterostructures causes major reabsorption losses at relatively short transport lengths. Doped NCs outperform the heterostructures substantially in this critical property. A new LSC phosphor is introduced, nanocrystalline Cd(1-x)Cu(x)Se, that outperforms all other leading NCs by a significant margin in both small- and large-scale LSCs under full-spectrum conditions.

  9. Wireless Luminescence Integrated Sensors (WLIS)

    SciTech Connect

    Simpson, M.L.; Sayler, G.S.

    2003-11-10

    The goal of this project was the development of a family of wireless, single-chip, luminescence-sensing devices to solve a number of difficult distributed measurement problems in areas ranging from environmental monitoring and assessment to high-throughput screening of combinatorial chemistry libraries. These wireless luminescence integrated sensors (WLIS) consist of a microluminometer, wireless data transmitter, and RF power input circuit all realized in a standard integrated circuit (IC) process with genetically engineered, whole-cell, bioluminescent bioreporters encapsulated and deposited on the IC. The end product is a family of compact, low-power, rugged, low-cost sensors. As part of this program they developed an integrated photodiode/signal-processing scheme with an rms noise level of 175 electrons/second for a 13-minute integration time, and a quantum efficiency of 66% at the 490-nm bioluminescent wavelength. this performance provided a detection limit of < 1000 photons/second. Although sol-gel has previously been used to encapsulate yeast cells, the reaction conditions necessary for polymerization (primarily low pH) have beforehand proven too harsh for bacterial cell immobilizations. Utilizing sonication methods, they have were able to initiate polymerization under pH conditions conductive to cell survival. both a toluene bioreporter (Pseudomonas putida TVA8) and a naphthalene bioreporter (Pseudomonas fluorescens HK44) were successfully encapsulated in sol-gel and shown to produce a fairly significant bioluminescent response. In addition to the previously developed naphthalene- and toluene-sensitive bioreporters, they developed a yeast-based xenoestrogen reporter. This technology has been licensed by Micro Systems Technologies, a startup company in Dayton, Ohio for applications in environmental containments monitoring, and for detecting weapons of mass destruction (i.e. homeland security).

  10. Bismuth tri- and tetraarylcarboxylates: crystal structures, in situ X-ray diffraction, intermediates and luminescence.

    PubMed

    Feyand, Mark; Köppen, Milan; Friedrichs, Gernot; Stock, Norbert

    2013-09-09

    A systematic investigation of the systems Bi(3+)/carboxylic acid/HNO3 for the tri- and tetracarboxylic acids pyromellitic acid (H4Pyr), trimellitic acid (H3Tri) and trimesic acid (H3BTC) acid led to the discovery of five new bismuth carboxylates. Structural characterisation allowed the influence of the linker geometry and the Bi(3+):linker molar ratio in the starting solution on the crystal structure to be determined. The crystallisation of three selected compounds was investigated by in situ energy-dispersive X-ray diffraction. Three new crystalline intermediates were observed within minutes, and two of them could be isolated by quenching of the reaction mixture. Their crystal structures were determined from laboratory and synchrotron X-ray powder diffraction data and allowed a possible reaction pathway to be established. In depth characterisation of the luminescence properties of the three bismuth pyromellate compounds was carried out. Fluorescence and phosphorescence could be assigned to (mainly) ligand- and metal-based transitions. The polymorphs of Bi(HPyr) exhibit different luminescence properties, although their structures are very similar. Surprisingly, doping of the three host structures with Eu(3+) and Tb(3+) ions was only successful for one of the polymorphs.

  11. Characterisation

    DTIC Science & Technology

    2007-03-01

    an tu m Cl as sic al spintronics Functional Metrology at the Nanoscale Super - paramagnetism Continuous current Nanoscale electrical conductance...Functional Metrology at the Nanoscale Super - paramagnetism Continuous current Nanoscale electrical conductance qubits Rapidly increasing complexity...micro-roughness, recessed structure and complex surfaces such as super polished surfaces • analysis of, super finished-machined components, soft

  12. Calibration beads containing luminescent lanthanide ion complexes

    EPA Science Inventory

    The reliability of lanthanide luminescence measurements, by both flow cytometry and digital microscopy, will be enhanced by the availability of narrow-band emitting lanthanide calibration beads. These beads can also be used to characterize spectrographic instruments, including mi...

  13. [Effect of "Fit" dishwashing detergent from former Eastern Germany (GDR) on luminol luminescence].

    PubMed

    Heuser, Katrin; Oehmen, Martin; Nadine, Kühner; Benecke, Mark

    2006-01-01

    The forensic luminol test is used to screen large areas for the presence of blood. The heme-induced reduction of hydrogen peroxide is coupled to the oxidation of luminol resulting in luminescence. However, photographic documentation of the relatively weak and short-lived luminescence is difficult and luminol is now often replaced by other chemicals. In this study, we investigated reports from the Rostock police department that the addition of "Fit", a dishwashing detergent from former Eastern Germany, could both intensify and prolong the luminescence of luminol on blood stains. Even though this effect was reported only for the original composition of Fit but not the currently sold version, we found that both the old and the new version of Fit increase the brightness of the luminescence while decreasing its duration. This may be due to detergents in the dishwashing liquid, which permeabilize the plasma membrane of the erythrocytes, exposing the Fe3+ inside the cell and speeding up the entire reaction. We did not find any evidence of special ingredients in the old version of Fit that would cause both the increased brightness and prolonged duration of luminescence as reported by the Rostock PD.

  14. Three-dimensional, multiwavelength Monte Carlo simulations of dermally implantable luminescent sensors

    NASA Astrophysics Data System (ADS)

    Long, Ruiqi; McShane, Mike

    2010-03-01

    Dermally implanted luminescent sensors have been proposed for monitoring of tissue biochemistry, which has the potential to improve treatments for conditions such as diabetes and kidney failure. Effective in vivo monitoring via noninvasive transdermal measurement of emission from injected microparticles requires a matched optoelectronic system for excitation and collection of luminescence. We applied Monte Carlo modeling to predict the characteristics of output luminescence from microparticles in skin to facilitate hardware design. Three-dimensional, multiwavelength Monte Carlo simulations were used to determine the spatial and spectral distribution of the escaping luminescence for different implantation depths, excitation light source properties, particle characteristics, and particle packing density. Results indicate that the ratio of output emission to input excitation power ranged 10-3 to 10-6 for sensors at the upper and lower dermal boundaries, respectively, and 95% of the escaping emission photons induced by a 10-mm-diam excitation beam were confined within an 18-mm circle. Tightly packed sensor configurations yielded higher output intensity with fewer particles, even after luminophore concentration effects were removed. Most importantly, for the visible wavelengths studied, the ability to measure spectral changes in emission due to glucose changes was not significantly affected by absorption and scattering of tissue, which supports the potential to accurately track changes in luminescence of sensor implants that respond to the biochemistry of the skin.

  15. X-ray excited optical luminescence : Understanding the light emission properties of silicon based nanostructures.

    SciTech Connect

    Sham, T.K.; Rosenberg, R. A.; Univ. of Western Ontario

    2007-01-01

    The recent advances in the study of light emission from matter induced by synchrotron radiation: X-ray excited optical luminescence (XEOL) in the energy domain and time-resolved X-ray excited optical luminescence (TRXEOL) are described. The development of these element (absorption edge) selective, synchrotron X-ray photons in, optical photons out techniques with time gating coincide with advances in third-generation, insertion device based, synchrotron light sources. Electron bunches circulating in a storage ring emit very bright, widely energy tunable, short light pulses (<100 ps), which are used as the excitation source for investigation of light-emitting materials. Luminescence from silicon nanostructures (porous silicon, silicon nanowires, and Si-CdSe heterostructures) is used to illustrate the applicability of these techniques and their great potential in future applications.

  16. Photochromic Terbium Phosphonates with Photomodulated Luminescence and Metal Ion Sensitive Detection.

    PubMed

    Yang, Weiting; Tian, Hong-Rui; Li, Jian-Ping; Hui, Yuan-Feng; He, Xiang; Li, Jiyang; Dang, Song; Xie, Zhigang; Sun, Zhong-Ming

    2016-10-17

    Rational selection and modification of rare earth metal centers and photoactive organic linkers enables designable multiphotofunctionality to come to fruition in new hybrid coordination polymer materials. By using a viologen-functionalized diphosphonate linker, two terbium phosphonate compounds (Tb-1 and Tb-2) have been constructed, which display reversible photochromic reactions in response to UV light and soft X-ray irradiation. In addition, the photo-induced electron-transfer reaction can modulate the luminescent emission to thus realize photoluminescence switching behavior. Furthermore, both terbium phosphonates can serve as highly sensitive sensors to probe Cu(2+) in solution through their luminescence. Thus, they represent the first photochromic examples of lanthanide phosphonate-based materials with photomodulated luminescence and sensitive detection of metal ions.

  17. Spectral analysis of delayed luminescence as a tool to discriminate between normal and cancer skin cells

    NASA Astrophysics Data System (ADS)

    Musumeci, F.; Scordino, A.; Tudisco, S.; Privitera, S.; Applegate, L. A.; Niggli, H. J.

    2005-08-01

    Photobiological research in the last decades has shown the existence of Delayed Luminescence in biological tissue, which presents an excitation spectrum with a peak within the UVA region and can be detected with sophisticated photomultiplier systems. Based on these findings, a new and powerful tool able to measure the UV-A-laser-induced Delayed Luminescence emission of cultured cells was developed, with the intention to detect biophysical changes between carcinogenic and normal cells. Indeed noticeable differences have been found in the time resolved emission spectrum of delayed luminescence of cell cultures of human fibroblast and human melanoma. This new, powerful and non-invasive technique, in principle, could be applied in all fields of skin research, such as the investigation of skin abnormalities and to test the effect of products involved in regeneration, anti-aging and UV-light protection in order to prevent skin cancer.

  18. Label-Free Luminescent Mesoporous Silica Nanoparticles for Imaging and Drug Delivery

    PubMed Central

    Chen, Hongmin; Zhen, Zipeng; Tang, Wei; Todd, Trever; Chuang, Yen-Jun; Wang, Lianchun; Pan, Zhengwei; Xie, Jin

    2013-01-01

    We report herein a straightforward and label-free approach to prepare luminescent mesoporous silica nanoparticles. We found that calcination at 400 °C can grant mesoporous organosilica nanoparticles with strong fluorescence of great photo- and chemical stability. The luminescence is found to originate from the carbon dots generated from the calcination, rather than the defects in the silica matrix as was believed previously. The calcination does not impact the particles' abilities to load drugs and conjugate to biomolecules. In a proof-of-concept study, we demonstrated that doxorubicin (Dox) can be efficiently encapsulated into these fluorescent mesoporous silica nanoparticles. After coupled to c(RGDyK), the nanoconjugates can efficiently home to tumors through interactions with integrin αvβ3 overexpressed on the tumor vasculature. This calcination-induced luminescence is expected to find wide applications in silica-based drug delivery, nanoparticle coating, and immunofluorescence imaging. PMID:24052805

  19. Luminescent photobioreactor design for improved algal growth and photosynthetic pigment production through spectral conversion of light.

    PubMed

    Mohsenpour, Seyedeh Fatemeh; Willoughby, Nik

    2013-08-01

    Growth characteristics of two strains of microalgae in bubble column photobioreactors were investigated under different cultivation conditions. Chlorella vulgaris and Gloeothece membranacea were cultivated in luminescent acrylic photobioreactors at different seed culture densities. Luminescent acrylic photobioreactors in blue, green, yellow, orange, and red colours capable of spectral conversion of light were used. The results indicated that the red luminescent photobioreactor enhanced biomass production in both strains of microalgae while pigmentation was induced under different light colours. Green light promoted chlorophyll production in C. vulgaris however chlorophyll production in G. membranacea cultures was less influenced by the light condition or culture density. Phycobiliproteins were the dominant pigments in G. membranacea and red light favoured synthesis of these pigments.

  20. Automated Sample Deoxygenation for Improved Luminescence Measurements.

    DTIC Science & Technology

    1986-11-25

    fET-AY4 732 AUTOMATED SAMPLE DEOXYGENATION FOR IMPROVED LUMINESCENCE MEASUREMENTS U) EMORY UNIV RTLANTA GA DEPT OF CHEMISTRY M E ROLLIE ET AL 25 NOV... Deoxygenation for Improved Luminescence Measurements 12 PERSONAL AUTHOR(S) | ,Rollie, M.E.; Patonay, Gabor; and Warner, Isiah M. A .3a. TYPE OF REPORT...GROUP ISU*GRO P ,,,uminescence Spectroscopy; Fluorescence Analysis,* Room *f Temperature Phosphorescence; Deoxygenation ; Quenching ISTRACT (Continue on

  1. Luminescence conversion of blue light emitting diodes

    NASA Astrophysics Data System (ADS)

    Schlotter, P.; Schmidt, R.; Schneider, J.

    Using blue-emitting GaN/6HSiC chips as primary light sources, we have fabricated green, yellow, red and white emitting LEDs. The generation of mixed colors, as turquoise and magenta is also demonstrated. The underlying physical principle is that of luminescence down-conversion (Stokes shift), as typical for organic luminescent dye molecules. A white emitting LED, using an inorganic converter, Y3Al5O12:Ce3+( ), has also been realized.

  2. Uranyl fluoride luminescence in acidic aqueous solutions

    SciTech Connect

    Beitz, J.V.; Williams, C.W.

    1996-08-01

    Luminescence emission spectra and decay rates are reported for uranyl species in acidic aqueous solutions containing HF or added NaF. The longest luminescence lifetime, 0.269 {+-} 0.006 ms, was observed from uranyl in 1 M HF + 1 M HClO{sub 4} at 296 K and decreased with increasing temperature. Based on a luminescence dynamics model that assumes equilibrium among electronically excited uranyl fluoride species and free fluoride ion, this long lived uranyl luminescence in aqueous solution is attributed primarily to UO{sub 2}F{sub 2}. Studies on the effect of added LiNO{sub 3} or Na{sub 2}WO{sub 4}{center_dot}2H{sub 2}O showed relatively weak quenching of uranyl fluoride luminescence which suggests that high sensitivity determination of the UF{sub 6} content of WF{sub 6} gas should be feasible via uranyl luminescence analysis of hydrolyzed gas samples of impure WF{sub 6}.

  3. An activatable, polarity dependent, dual-luminescent imaging agent with a long luminescence lifetime.

    PubMed

    Rood, Marcus T M; Oikonomou, Maria; Buckle, Tessa; Raspe, Marcel; Urano, Yasuteru; Jalink, Kees; Velders, Aldrik H; van Leeuwen, Fijs W B

    2014-09-04

    In this proof-of-concept study, a new activatable imaging agent based on two luminophores and two different quenching mechanisms is reported. Both partial and total activation of the luminescence signal can be achieved, either in solution or in vitro. Bond cleavage makes the compound suitable for luminescence lifetime imaging.

  4. Materials characterisation with the associated particle technique

    SciTech Connect

    Perot, Bertrand; Carasco, Cedric; Deyglun, Clement; Eleon, Cyrille; Mariani, Alain; Ma, Jean-Luc

    2012-07-01

    Since the last past years, the Nuclear Measurement Laboratory of CEA Cadarache, France, together with Partners from European and National projects, has been studying the application of fast neutron interrogation with the Associated Particle Technique for material identification in different areas of homeland and maritime security, and for the characterisation of the materials constituting radioactive waste. Fast 14 MeV neutrons are produced from the H-3(H-2,n)alpha fusion reaction in a sealed tube neutron generator embedding an alpha detector. The alpha particle is used to tag neutron direction and emission time, thus allowing the electronic selection of neutron-induced gamma spectra in the voxels of interest. Gamma rays emitted by tagged neutron interactions on the present nuclei (C, O, N, Fe, Al, Si, Cl, etc.) are recorded with spectroscopic detectors and analysed to determine elemental proportions, thus allowing material identification. Investigations have been conducted for the detection of explosives, illicit drugs and contraband materials in cargo containers, for the inspection of objects lying on the sea floor suspected to contain explosives like mines, bombs, torpedoes, etc., for the recognition of an improvised chemical device, and for material identification in radioactive waste packages. Recently the detection of special nuclear materials is being investigated using time correlation analysis between induced fission particles, instead of gamma-ray spectroscopy. The paper presents an overview of these studies and last results. (authors)

  5. Extraction Methods in Soil Phosphorus Characterisation

    NASA Astrophysics Data System (ADS)

    Soinne, Helena

    2010-05-01

    Extraction methods are widely used to assess the bioavailability of P and to characterise soil P reserves. Even though new and more sophisticated methods to characterise soil P are constantly developed the use of extraction methods is not likely to be replaced because of the relatively simple analytical equipment needed for the analysis. However, the large variety of extractants, pre-treatments and sample preparation procedures complicate the comparison of published results. In order to improve our understanding of the behaviour and cycling of P in soil, it is important to know the role of extracted P in the soil P cycle. The knowledge of the factors affecting the analytical outcome is a prerequisite for justified interpretation of the results. In this study, the effect of sample pre-treatment and properties of the used extractant on extractable molybdate-reactive phosphorus (MRP) and molybdate-unreactive phosphorus (MUP) was studied. Furthermore, the effect of sample preparation procedures prior the analysis on measured MRP and MUP was studied. Two widely used sequential extraction procedures were compared on their ability to show management induced differences on soil P. These results revealed that pre-treatments changed soil properties and air-drying was found to affect soil P, particularly extractable MUP, thought to represent organic P, by disrupting organic matter. This was evidenced by an increase in the water-extractable small-sized (<0.2 µm) P that, at least partly, took place at the expense of the large-sized (>0.2 µm) P. In addition to the effects of sample pre-treatment, the results showed that extractable organic P was sensitive to the chemical nature of the used extractant and to the sample preparation procedures employed prior to P analysis, including centrifugation and filtering of soil suspensions. Filtering may remove a major proportion of extractable MUP; therefore filtering cannot be recommended in the characterisation of solubilised MUP

  6. Detecting Thermal Barrier Coating Delamination Using Visible and Near-Infrared Luminescence from Erbium-Doped Sublayers

    NASA Technical Reports Server (NTRS)

    Eldridge, J. I.; Bencic, T. J.; Martin, R. E.; Singh, J.; Wolfe, D. E.

    2007-01-01

    Nondestructive diagnostic tools are needed to monitor early stages of delamination progression in thermal barrier coatings (TBCs) because the risk of delamination induced coating failure will compromise engine performance and safety. Previous work has demonstrated that for TBCs composed of yttria-stabilized zirconia (YSZ), luminescence from a buried europium-doped sublayer can be utilized to identify the location of TBC delamination from the substantially higher luminescence intensity observed from the delaminated regions of the TBC. Luminescence measurements from buried europium-doped layers depend on sufficient transmittance of the 532 nm excitation and 606 nm emission wavelengths through the attenuating undoped YSZ overlayer to produce easily detected luminescence. In the present work, improved delamination indication is demonstrated using erbium-doped YSZ sublayers. For visible-wavelength luminescence, the erbium-doped sublayer offers the advantage of a very strong excitation peak at 517 nm that can be conveniently excited a 514 nm Ar ion laser. More importantly, the erbium-doped sublayer also produces near-infrared luminescence at 1550 nm that is effectively excited by a 980 nm laser diode. Both the 980 nm excitation and the 1550 nm emission are transmitted through the TBC with much less attenuation than visible wavelengths and therefore show great promise for delamination monitoring through thicker or more highly scattering TBCs. The application of this approach for both electron beam physical vapor deposited (EB-PVD) and plasma-sprayed TBCs is discussed.

  7. Luminescent tetrametallic complexes of ruthenium

    SciTech Connect

    Murphy, W.R. Jr.; Brewer, K.J.; Gettliffe, G.; Petersen, J.D. )

    1989-01-11

    Tetrametallic complexes constructed around the metal core Ru(dpp){sub 3}{sup 2+} (where dpp = 2,3-bis(2-pyridyl)pyrazine) have been prepared and characterized. The complexes, which have the general formula Ru((dpp)ML{sub 2}){sub 3}{sup n+}, where ML{sub 2} = Ru{sup II}(bpy){sub 2} (n = 8), Ru{sup II}(phen){sub 2} (n = 8), and Ru{sup II}(tpy)Cl (n = 5) and bpy = 2,2{prime}-bipyridine, phen = 1,10-phenanthroline, and tpy = 2,2{prime}:6{prime},2{double prime}-terpyridine, are prepared from the reaction of Ru(dpp){sub 3}{sup 2+} with ML{sub 2}Cl{sub 2} in ethanol/water. The tetrametallic complexes luminesce at room temperature in acetonitrile with emissions characteristic of a single ruthenium center with excited-state lifetimes in the 100-ns range. Electrochemically, the most facile reductions occur at the dpp ligand, and the lower energy oxidation is a single peak associated with the three peripheral ruthenium centers. 13 refs., 1 fig., 2 tabs.

  8. Development of a terbium complex-based luminescent probe for imaging endogenous hydrogen peroxide generation in plant tissues.

    PubMed

    Ye, Zhiqiang; Chen, Jinxue; Wang, Guilan; Yuan, Jingli

    2011-06-01

    A highly sensitive Tb(3+) complex-based luminescent probe, N,N,N(1),N(1)-[2,6-(3'-aminomethyl-1'-pyrazolyl)-4-(3'',4''-diaminophenoxy)methylene-pyridine] tetrakis(acetate)-Tb(3+) (BMTA-Tb(3+)), has been designed and synthesized for the recognition and detection of hydrogen peroxide (H(2)O(2)) in aqueous solutions. This probe is almost nonluminescent because the Tb(3+) luminescence is effectively quenched by the electron-rich moiety, diaminophenyl, on the basis of the photoinduced electron transfer (PET) mechanism. In the presence of peroxidase, the probe can react with H(2)O(2) to cause the cleavage of the diaminophenyl ether, which affords a highly luminescent Tb(3+) complex, N,N,N(1),N(1)-[2,6-bis(3'-aminomethyl-1'-pyrazolyl)-4-hydroxymethyl-pyridine] tetrakis(acetate)-Tb(3+) (BHTA-Tb(3+)), accompanied by a 39-fold increase in luminescence quantum yield with the increase of luminescence lifetime from 1.95 to 2.76 ms. The dose-dependent luminescence enhancement of the probe shows a good linearity with a detection limit of 3.7 nM for H(2)O(2), which is approximately 14-fold lower than those of the commonly used fluorescent probes. The probe was used for the time-resolved luminescence imaging detection of the oligosaccharide-induced H(2)O(2) generation in tobacco leaf epidermal tissues. On the basis of the probe, a background-free time-resolved luminescence imaging method for detecting H(2)O(2) in complicated biological systems was successfully established.

  9. Luminescence and ESR studies of relationships between O(-)-centres and structural iron in natural and synthetically hydrated kaolinites

    NASA Technical Reports Server (NTRS)

    Coyne, L. M.; Costanzo, P. M.; Theng, B. K.

    1989-01-01

    Luminescence, induced by dehydration and by wetting with hydrazine and unsymmetrically substituted hydrazine, and related ESR spectra have been observed from several kaolinites, synthetically hydrated kaolinites, and metahalloysites. The amine-wetting luminescence results suggest that intercalation, not a chemiluminescence reaction, is the luminescence trigger. Correlation between hydration-induced luminescence and g = 2 ESR signals associated with O(-)-centres in several natural halloysites, and concurrent diminution of the intensity of both these signal types as a function of aging in two 8.4 angstroms synthetically hydrated, kaolinites, confirm a previously-reported relationship between the luminescence induced by dehydration and in the presence of O(-)-centres (holes, i.e., electron vacancies) in the tetrahedral sheet. Furthermore, the ESR spectra of the 8.4 angstroms hydrate showed a concurrent change in the line shape of the g = 4 signal from a shape usually associated with structural Fe in an ordered kaolinite, to a simpler one typically observed in more disordered kaolinite, halloysite, and montmorillonite. Either structural Fe centres and the O(-)-centres interact, or both are subject to factors previously associated with degree of order. The results question the long-term stability of the 8.4 angstroms hydrate, although XRD does not indicate interlayer collapse over this period. Complex inter-relationships are shown between intercalation, stored energy, structural Fe, and the degree of hydration which may be reflected in catalytic as well as spectroscopic properties of the clays.

  10. Monitoring Temperatures of Tires Using Luminescent Materials

    NASA Technical Reports Server (NTRS)

    Bencic, Timothy J

    2006-01-01

    A method of noncontact, optical monitoring of the surface temperature of a tire has been devised to enable the use of local temperature rise as an indication of potential or impending failures. The method involves the use of temperature-sensitive paint (or filler): Temperature-sensitive luminescent dye molecules or other luminescent particles are incorporated into a thin, flexible material coating the tire surface of interest. (Alternatively, in principle, the luminescent material could be incorporated directly into the tire rubber, though this approach has not yet been tested.) The coated surface is illuminated with shorter-wavelength light to excite longer-wavelength luminescence, which is observed by use of a charge-coupled-device camera or a photodetector (see Figure 1). If temporally constant illumination is used, then the temperature can be deduced from the known temperature dependence of the intensity response of the luminescence. If pulsed illumination is used, then the temperature can be deduced from the known temperature dependence of the time or frequency response of the luminescence. If sinusoidally varying illumination is used, then the temperature can be deduced from the known temperature dependence of the phase response of the luminescence. Unlike a prior method of monitoring the temperature at a fixed spot on a tire by use of a thermocouple, this method is not restricted to one spot and can, therefore, yield information on the spatial distribution of temperature: in particular, it enables the discovery of newly forming hot spots where damage may be starting. Also unlike in the thermocouple method, the measurements in this method are not vulnerable to breakage of wires in repeated flexing of the tire. Moreover, unlike in another method in which infrared radiation is monitored as an indication of surface temperature, the luminescence measurements in this method are not significantly affected by changes in infrared emissivity. This method has been

  11. Highly sensitive nonlinear luminescent ceramics for volumetric and multilayer data carriers

    SciTech Connect

    Martynovich, E F; Dresvyanskiy, V P; Voitovich, A P; Bagayev, S N

    2015-10-31

    The interaction of optical ceramics based on wide-bandgap crystals with near-IR femtosecond laser radiation is studied experimentally. The formation of luminescent centres in LiF and MgF{sub 2} ceramics under the action of single laser pulses is considered. Two interaction regimes are used. In the regime of low-aperture focusing of laser radiation (800 nm, 30 fs, 0.3 mJ), multiple selffocusing and filamentation in the samples are observed. The luminescent centres are formed in thin channels induced by light filaments. The average effective self-focusing length is ∼100 μm; the formation of luminescent centres begins at this length and ceases at a wavelength of about 380 mm. The luminescent trace (spur) induced by a single laser filament was ∼30 μm long and 1.3 μm in diameter. The second regime of light interaction with the sample was based on high-aperture focusing with a simultaneous decrease in the laser pulse energy. This led to the formation of single pits with a diameter smaller than the optical diffraction limit. The luminescent centres induced by the laser radiation were aggregated colour centres. The mechanism of their creation included the highly-nonlinear generation of electron – hole pairs in the filamentation region, their recombination with the formation of anion excitons and the decay of excitons into Fresnel defects by the Lushchik – Vitol – Hersh – Pooley mechanism, as well as their recharging, migration and aggregation. (laser applications and other topics in quantum electronics)

  12. 21 CFR 73.2995 - Luminescent zinc sulfide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Luminescent zinc sulfide. 73.2995 Section 73.2995... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2995 Luminescent zinc sulfide. (a) Identity. The color additive luminescent zinc sulfide is zinc sulfide containing a copper activator....

  13. 21 CFR 73.2995 - Luminescent zinc sulfide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Luminescent zinc sulfide. 73.2995 Section 73.2995... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2995 Luminescent zinc sulfide. (a) Identity. The color additive luminescent zinc sulfide is zinc sulfide containing a copper activator....

  14. 21 CFR 73.2995 - Luminescent zinc sulfide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Luminescent zinc sulfide. 73.2995 Section 73.2995... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2995 Luminescent zinc sulfide. (a) Identity. The color additive luminescent zinc sulfide is zinc sulfide containing a copper activator....

  15. 21 CFR 73.2995 - Luminescent zinc sulfide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Luminescent zinc sulfide. 73.2995 Section 73.2995... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2995 Luminescent zinc sulfide. (a) Identity. The color additive luminescent zinc sulfide is zinc sulfide containing a copper activator....

  16. 21 CFR 73.2995 - Luminescent zinc sulfide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Luminescent zinc sulfide. 73.2995 Section 73.2995... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2995 Luminescent zinc sulfide. (a) Identity. The color additive luminescent zinc sulfide is zinc sulfide containing a copper activator....

  17. Effect of irradiation and thermal annealing on quartz materials luminescence

    NASA Astrophysics Data System (ADS)

    Korovkin, M. V.; Ananyeva, L. G.

    2017-01-01

    X-ray and gamma-quanta irradiation of radiation-resistant quartz materials including natural and synthetic quartz crystals and high-purity quartzite causes the luminescence in the ultraviolet range (365 nm), thermally stimulated luminescence and radiofrequency electromagnetic emission. Preliminary radiation and thermal annealing improves luminescence properties of quartz materials.

  18. Luminescence of europium (III) complexes for visualization

    NASA Astrophysics Data System (ADS)

    Kolontaeva, Olga A.; Pozharov, Mikhail V.; Korolovich, Vladimir F.; Khokhlova, Anastasia R.; Kirdyanova, Anna N.; Burmistrova, Natalia A.; Zakharova, Tamara V.; Goryacheva, Irina Y.

    2016-04-01

    With the purpose to develop bright non-toxic luminescent label for theranostic application we have studied complexation of lanthanide dipicolinates (2,6-pyridinedicarboxylates) by sodium alginate and effect of thermal exposure of synthesized micro-capsules on their luminescent properties. Synthesized micro-capsules are stable in acidic medium but dissolve at pH ~ 4 due to transformation of cationic europium dipicolinate complex to anionic. Luminescence studies have shown that emission spectra of europium(III)-alginate complexes (both chloride and dipicolinate) contain two intensive bands characteristic to Eu3+ ion (5D0 --> 7F1 (590 nm) and 5D0 --> 7F1 (612 nm)). We have also found that at 160ºC europium(III)- alginate micro-capsules decompose to black, soot-like substance, therefore, their thermal treatment must be performed in closed environment (i.e., sealed ampoules).

  19. Dual Luminescence Imaging for Two Phase Flow

    NASA Astrophysics Data System (ADS)

    Sakaue, Hirotaka; Morita, Katsuaki

    2016-11-01

    Dual luminescence imaging gives time-resolved information of fluid dynamic phenomena. It uses two luminescent probes; one is sensitive to the detecting medium and the other as a reference. It is a non-intrusive technique, and both luminescent outputs are captured by a high-speed color camera as color-filtered images. By taking a ratio of the two images at the same time frame, this imaging technique can give time-resolved information. It is suitable for a moving and free surface objects. It is also suitable for a measurement where a target is small to mount a conventional thermocouple and pressure probes. Some of the applications of this imaging are described in the presentation, such as icing and boiling phenomena.

  20. [Synthesis of reserve polyhydroxyalkanoates by luminescent bacteria].

    PubMed

    Boiandin, A N; Kalacheva, G S; Rodicheva, E K; Volova, T G

    2008-01-01

    The ability of marine luminescent bacteria to synthesize polyesters of hydroxycarboxylic acids (polyhydroxyalkanoates, PHA) as reserve macromolecules was studied. Twenty strains from the collection of the luminescent bacteria CCIBSO (WDSM839) of the Institute of Biophysics, Siberian Branch, Russian Academy of Sciences, assigned to different taxa (Photobacterium leiognathi, Ph. phosphoreum, Vibrio harveyi, and V. fischeri) were analyzed. The most productive strains were identified, and the conditions ensuring high polymer yields in batch culture (40-70% of the cell dry mass weight) were determined. The capacity of synthesizing two- and three-component polymers containing hydroxybutyric acid as the main monomer and hydroxyvaleric and hydroxyhexanoic acids was revealed in Ph. leiognathi and V. harveyi strains. The results allow luminescent microorganisms to be regarded as new producers of multicomponent polyhydroxyalkanoates.

  1. Spectral luminescence analysis of amniotic fluid

    NASA Astrophysics Data System (ADS)

    Slobozhanina, Ekaterina I.; Kozlova, Nataly M.; Kasko, Leonid P.; Mamontova, Marina V.; Chernitsky, Eugene A.

    1997-12-01

    It is shown that the amniotic fluid has intensive ultra-violet luminescence caused by proteins. Along with it amniotic fluid radiated in the field of 380 - 650 nm with maxima at 430 - 450 nm and 520 - 560 nm. The first peak of luminescence ((lambda) exc equals 350 nm; (lambda) em equals 430 - 440 nm) is caused (most probably) by the presence in amniotic fluid of some hormones, NADH2 and NADPH2. A more long-wave component ((lambda) exc equals 460 nm; (lambda) em equals 520 - 560 nm) is most likely connected with the presence in amniotic fluid pigments (bilirubin connected with protein and other). It is shown that intensity and maximum of ultra-violet luminescence spectra of amniotic fluid in normality and at pathology are identical. However both emission spectra and excitation spectra of long-wave ((lambda) greater than 450 nm) luminescence of amniotic fluid from pregnant women with such prenatal abnormal developments of a fetus as anencephaly and spina bifida are too long-wave region in comparison with the norm. Results of research testify that spectral luminescent analysis of amniotic fluid can be used for screening of malformations of the neural tube. It is very difficult for a practical obstetrician to reveal pregnant women with a high risk of congenital malformations of the fetus. Apart from ultrasonic examination, cytogenetic examination of amniotic fluid and defumination of concentrations of alpha-fetoprotein and acetylcholin-esterases in the amniotic fluid and blood plasma are the most widely used diagnostic approaches. However, biochemical and cytogenetic diagnostic methods are time-consuming. In the present work spectral luminescence properties of the amniotic fluid are investigated to determine spectral parameters that can be used to reveal pregnant women with a high risk of congenital malformations of their offsprings.

  2. Emissive Molecular Aggregates and Energy Migration in Luminescent Solar Concentrators.

    PubMed

    Banal, James L; Zhang, Bolong; Jones, David J; Ghiggino, Kenneth P; Wong, Wallace W H

    2017-01-17

    of chromophores exhibiting aggregation-induced emission (AIE) behavior are attractive candidates for LSC applications. Strategic application of AIE chromophores has led to the development of the first organic-based transparent solar concentrator that harvests UV light as well as the demonstration of reabsorption reduction by taking advantage of energy migration processes between chromophores. Further developments led us to the application of perylene diimides using an energy migration/energy transfer approach. To prevent concentration quenching, a molecularly insulated perylene diimide with bulky substituents attached to the imide positions was designed and synthesized. By combining the insulated perylene diimide with a commercial perylene dye as an energy donor-acceptor emitter pair, detrimental luminescence reabsorption was reduced while achieving a high chromophore concentration for efficient light absorption. This Account reviews and reinspects some of our recent work and the improvements in the field of LSCs.

  3. Menadione-catalyzed luminol luminescent assay as a novel evaluation method of ethanol tolerance in yeast cells.

    PubMed

    Yamashoji, Shiro

    2009-02-01

    In this study, ethanol inhibited the growth and glucose-induced proton release of yeast cells in a dose-dependent manner. On the other hand, ethanol tolerance of menadione-catalyzed luminol luminescence by yeast cells increased with increasing ethanol concentrations in the growth medium. The intracellular reduced-form nicotinamide adenine dinucleotide (NADH) concentration also increased with increasing ethanol concentrations in the medium and was enough to maintain constant menadione-catalyzed luminol luminescence. These facts suggest that the menadione-catalyzed luminol luminescent assay depending on a NADH:quinone reductase and NADH generation system is useful as a new evaluation assay for assessing the vitality of ethanol-stressed yeast cells, whereas the glucose-induced proton release assay is expected to be useful for the evaluation of cell growth under ethanol stress.

  4. Luminescence of apollo 11 lunar samples.

    PubMed

    Greenman, N N; Gross, H G

    1970-01-30

    Luminescence measurements were made of four lunar rocks, two terrestrial rocks (granite and gabbro), and one terrestrial mineral (willemite) by comparing the spectral curves with the curve of a barium sulfate standard. Efficiencies with 3000 angstrom excitation were < 6 x 10(-5) for the lunar samples, < 8 x 10(-5) for gabbro of very similar composition to the lunar samples, approximately 10(-4) for granite, and approximately 2 X 10(-2) for willemite. If these are typical values for other ultraviolet excitation wavelengths, the Apollo 11 site appears to contribute little to the observed lunar luminescence.

  5. Simultaneous Luminescence Pressure and Temperature Mapping

    NASA Technical Reports Server (NTRS)

    Buck, Gregory M. (Inventor)

    1998-01-01

    A simultaneous luminescence pressure and temperature mapping system is developed including improved dye application techniques for surface temperature and pressure measurements from 5 torr to 1000 torr with possible upgrade to from 0.5 torr to several atmospheres with improved camera resolution. Adsorbed perylene dye on slip-cast silica is pressure (oxygen) sensitive and reusable to relatively high temperatures (-150 C). Adsorbed luminescence has an approximately linear color shift with temperature, which can be used for independent temperature mapping and brightness pressure calibration with temperature.

  6. Simultaneous Luminescence Pressure and Temperature Mapping System

    NASA Technical Reports Server (NTRS)

    Buck, Gregory M. (Inventor)

    1995-01-01

    A simultaneous luminescence pressure and temperature mapping system is developed including improved dye application techniques for surface temperature and pressure measurements from 5 torr to 1000 torr with possible upgrade to from 0.5 torr to several atmospheres with improved camera resolution. Adsorbed perylene dye on slip-cast silica is pressure (oxygen) sensitive and reusable to relatively high temperatures (approximately 150 C). Adsorbed luminescence has an approximately linear color shift with temperature, which can be used for independent temperature mapping and brightness pressure calibration with temperature.

  7. Lanthanide luminescence for functional materials and bio-sciences.

    PubMed

    Eliseeva, Svetlana V; Bünzli, Jean-Claude G

    2010-01-01

    Recent startling interest for lanthanide luminescence is stimulated by the continuously expanding need for luminescent materials meeting the stringent requirements of telecommunication, lighting, electroluminescent devices, (bio-)analytical sensors and bio-imaging set-ups. This critical review describes the latest developments in (i) the sensitization of near-infrared luminescence, (ii) "soft" luminescent materials (liquid crystals, ionic liquids, ionogels), (iii) electroluminescent materials for organic light emitting diodes, with emphasis on white light generation, and (iv) applications in luminescent bio-sensing and bio-imaging based on time-resolved detection and multiphoton excitation (500 references).

  8. Fabrication of luminescent porous silicon with stain etches and evidence that luminescence originates in amorphous layers

    NASA Technical Reports Server (NTRS)

    Fathauer, R. W.; George, T.; Ksendzov, A.; Lin, T. L.; Pike, W. T.; Vasquez, R. P.; Wu, Z.-C.

    1992-01-01

    Simple immersion of Si in stain etches of HF:HNO3:H2O or NaNO2 in aqueous HF was used to produce films exhibiting luminescence in the visible similar to that of anodically-etched porous Si. All of the luminescent samples consist of amorphous porous Si in at least the near surface region. No evidence was found for small crystalline regions within these amorphous layers.

  9. Enhancing and quenching luminescence with gold nanoparticle films: the influence of substrate on the luminescent properties

    NASA Astrophysics Data System (ADS)

    José Guidelli, Eder; Ramos, Ana Paula; Baffa, Oswaldo

    2016-01-01

    Gold nanoparticle (AuNP) films were sputtered over glass and aluminum substrates to enhance optically stimulated luminescence (OSL), a luminescent technique employed for radiation detection, from x-ray irradiated NaCl nanocrystals. The AuNP films deposited over glass led to enhanced-OSL emission, whereas the AuNP films deposited on aluminum substrates quenched the OSL emission. The enhanced-OSL intensity is proportional to the optical density of the film's plasmon resonance band at the stimulation wavelength. For the case of the AuNP/aluminum films, the luminescence quenching diminishes, and OSL intensity partially recovers upon increasing the distance between the AuNPs and the aluminum substrates, and between the luminescent nanocrystals and the AuNP films. These results suggest that plasmonic interactions between the emitter nanocrystals, the localized surface plasmons (LSP) of the AuNPs, and the substrate are responsible for the OSL enhancement and quenching. In this sense, the substrate dictates whether LSP relaxation occurs by radiative or non-radiative transisitions, leading to enhanced or quenched OSL, respectively. Therefore, besides showing that AuNP films can enhance and/or tune the sensitivity of luminescent radiation detectors, and demonstrating OSL as a new technique to investigate mechanisms of plasmon-enhanced luminescence, these results bring insights on how substrates strongly modify the optical properties of AuNP films.

  10. Thermal and electron stimulated luminescence of natural bones, commercial hydroxyapatite and collagen.

    PubMed

    Roman-Lopez, J; Correcher, V; Garcia-Guinea, J; Rivera, T; Lozano, I B

    2014-01-01

    The luminescence (cathodoluminescence and thermoluminescence) properties of natural bones (Siberian mammoth and adult elephant), commercial hydroxyapatite and collagen were analyzed. Chemical analyses of the natural bones were determined using by Electron Probe Micro-Analysis (EMPA). Structural, molecular and thermal characteristics were determined by X-ray Diffraction (XRD), Raman spectroscopy and Differential Thermal and Thermogravimetric analysis (DTA-TG). Cathodoluminescence (CL) spectra of natural bones and collagen showed similar intense broad bands at 440 and 490 nm related to luminescence of the tetrahedral anion [Formula: see text] or structural defects. A weaker luminescence exhibited at 310 nm could be attributed to small amount of rare earth elements (REEs). Four luminescent bands at 378, 424, 468 and 576 nm were observed in the commercial hydroxyapatite (HAP). Both natural bones and collagen samples exhibited natural thermoluminescence (NTL) with well-defined glow curves whereas that the induced thermoluminescence (ITL) only appears in the samples of commercial hydroxyapatite and collagen. Additional explanations for the TL anomalous fading of apatite, as a crucial difficulty performing dosimetry and dating, are also considered.

  11. Acid synthesis of luminescent amine-functionalized or erbium-doped silica spheres for biological applications.

    PubMed

    Enrichi, Francesco; Trave, Enrico; Bersani, Marco

    2008-03-01

    In this work we discuss and investigate the morphological and optical properties of luminescent silica spheres which can have interesting applications in bioimaging and biosensing. The spheres are synthesized following an acid route by the hydrolysis and condensation of tetraethylortosilicate (TEOS) and can be functionalized by incorporation of aminopropyl-triethoxysilane (APTES) during the synthesis, inducing a significant luminescence that can be attributed to a recombination mechanism from localized organic defects related to -NH(2) groups. It is shown that the acid synthesis route produces very regular spherical particles, but their diameter vary in the range of 200-4,000 nm. The luminescence properties have been investigated and optimized by variation of the annealing temperature for the functionalized spheres, obtaining the most efficient PL emission after a thermal treatment of 1 h at 600 degrees C in air. Moreover, the possibility to introduce rare earths like erbium in the spheres was also studied and the corresponding Er(3) luminescence emission at 1.53 microm is reported in terms of intensity and lifetime, pointing out that erbium can be easily and efficiently incorporated during the acid synthesis giving high PL intensity with a good lifetime of 3.9 ms.

  12. Effects of hydrogen peroxide on light emission by various strains of marine luminescent bacteria.

    PubMed

    Katsev, Andrey M; Wegrzyn, Grzegorz; Szpilewska, Hanna

    2004-01-01

    Light-emitting bacteria are the most abundant and widespread luminescent organisms. Most species of such bacteria live in marine environments. However, until recently, biological role of bacterial luminescence remained unknown. Recent studies indicated that light produced in bacterial cells may stimulate DNA repair. Therefore, it is not surprising that agents that cause DNA damage induce expression of lux genes. Moreover, it was proposed previously that bacterial luciferases may be involved in detoxification of reactive oxygen species. Recently, this hypothesis was confirmed experimentally. Here we investigated effects of hydrogen peroxide on light emission by various strains of luminescent bacteria. We found that luminescence of strains with luciferase of fast kinetics of reaction decreased at considerably lower concentrations of H2O2 than that of strains with luciferase of the slow kinetics. The action (either direct or indirect) of luciferases as anti-oxidants seemed to be independent of activity of catalase, which was found to be different in various strains. Therefore, it seems that luciferases of the slow kinetics are more efficient in detoxification of reactive oxygen species than those of the fast kinetics.

  13. Luminescence from Erbium Oxide Grown on Silicon

    DTIC Science & Technology

    2002-01-01

    H9.14 Luminescence from erbium oxide grown on silicon E. Nogales’, B. Mrndez , J.Piqueras’, R.Plugaru2 , J. A. Garcfa3 and T. J. Tate4 ’ Universidad ... Complutense de Madrid, Dpto. Ffsica de Materiales, 28040 Madrid, Spain.2Inst. of Microtechnology, Bucharest, Romania.3Universidad del Pais Vasco, Dpto

  14. Modeling Light Propagation in Luminescent Media

    NASA Astrophysics Data System (ADS)

    Sahin, Derya

    This study presents physical, computational and analytical modeling approaches for light propagation in luminescent random media. Two different approaches are used, namely (i) a statistical approach: Monte-Carlo simulations for photon transport and (ii) a deterministic approach: radiative transport theory. Both approaches account accurately for the multiple absorption and reemission of light at different wavelengths and for anisotropic luminescence. The deterministic approach is a generalization of radiative transport theory for solving inelastic scattering problems in random media. We use the radiative transport theory to study light propagation in luminescent media. Based on this theory, we also study the optically thick medium. Using perturbation methods, a corrected diffusion approximation with asymptotically accurate boundary conditions and a boundary layer solution are derived. The accuracy and the efficacy of this approach is verified for a plane-parallel slab problem. In particular, we apply these two approaches (MC and radiative transport theory) to model light propagation in semiconductor-based luminescent solar concentrators (LSCs). The computational results for both approaches are compared with each other and found to agree. The results of this dissertation present practical and reliable techniques to use for solving forward/inverse inelastic scattering problems arising in various research areas such as optics, biomedical engineering, nuclear engineering, solar science and material science.

  15. Luminescence Originating in an Optical Fiber

    DTIC Science & Technology

    1988-10-28

    TIME COVERED /1 14. DATE OF REPORT (Year Month, Oay) S.PAGE COUNT Technical FROM TO_ _ 28 October 1988 12 16. SUPPLEMENTARY NOTATION Applied ... Spectroscopy 17. COSATI CODES18. SUB Eg.TERMS (Continue on reverse if necessary and identify by block number) FIED OUPU Optical Fibers, Luminescence, Sensors

  16. Increasing the luminescence of lanthanide complexes.

    PubMed

    Leif, Robert C; Vallarino, Lidia M; Becker, Margie C; Yang, Sean

    2006-08-01

    This review compares the chemical and physical properties of lanthanide ion complexes and of other narrow-emitting species that can be used as labels for cytometry. A series of luminescent lanthanide ion macrocyclic complexes, Quantum Dyes, which do not release or exchange their central lanthanide ion, do accept energy transfer from ligands, and are capable of covalent binding to macromolecules, including proteins and nucleic acids, is described and their properties are discussed. Two methods are described for increasing the luminescence intensity of lanthanide ion complexes, which intrinsically is not as high as that of standard fluorophores or quantum dots. One method consists of adding a complex of a second lanthanide ion in a micellar solution (columinescence); the other method produces dry preparations by evaporation of a homogeneous solution containing an added complex of a second lanthanide ion or an excess of an unbound antenna ligand. Both methods involve the Resonance Energy Transfer Enhanced Luminescence, RETEL, effect as the mechanism for the luminescence enhancement.

  17. Bright and multicolor luminescent colloidal Si nanocrystals prepared by pulsed laser irradiation in liquid

    SciTech Connect

    Nakamura, Toshihiro Watanabe, Kanta; Adachi, Sadao; Yuan, Ze

    2016-01-11

    We reported the preparation of bright and multicolor luminescent colloidal Si nanocrystal (Si-nc) by pulsed UV laser irradiation to porous Si (PSi) in an organic solvent. The different-luminescence-color (different-sized) colloidal Si-nc was produced by the pulsed laser-induced fragmentation of different-sized porous nanostructures. The colloidal Si-nc samples were found to have higher photoluminescence quantum efficiencies (20%–23%) than the PSi samples (1%–3%). The brighter emission of the colloidal Si-nc was attributed to an enhanced radiative band-to-band transition rate due to the presence of a surface organic layer formed by UV laser-induced hydrosilylation.

  18. Simultaneous Luminescence Pressure and Temperature Measurement System for Hypersonic Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Buck, Gregory M.

    1995-01-01

    Surface pressures and temperatures are determined from visible emission brightness and green-to-red color ratioing of induced luminescence from a ceramic surface with an organic dye coating. A ceramic-dye matrix of porous silica ceramic with an adsorbed dye is developed for high-temperature pressure sensitivity and stability (up to 150 C). Induced luminescence may be excited using a broad range of incident radiation from visible blue light (488-nm wavelength) to the near ultraviolet (365 nm). Ceramic research models and test samples are fabricated using net-form slip-casting and sintering techniques. Methods of preparation and effects of adsorption film thickness on measurement sensitivity are discussed. With the present 8-bit imaging system a 10% pressure measurement uncertainty from 50 to 760 torr is estimated, with an improvement to 5% from 3 to 1500 torr with a 12-bit imaging system.

  19. Simultaneous ion luminescence imaging and spectroscopy of individual aerosol particles with external proton or helium microbeams

    NASA Astrophysics Data System (ADS)

    Kada, Wataru; Satoh, Takahiro; Yokoyama, Akihito; Koka, Masashi; Kamiya, Tomihiro

    2014-08-01

    Simultaneous microscopic imaging and spectroscopy of individual aerosol particles were performed with an external microbeam. Visible luminescence induced by the external microbeam was successfully used as a probe to detect organic contaminants in the targets. Combined ion luminescence (IL)/particle-induced X-ray emission (PIXE) analysis of the aerosol targets revealed microscopic chemical and elemental composition distributions under ambient atmospheric conditions. The simple confocal micro-optics for the IL spectroscopy and microscopic imaging were sufficiently sensitive for detecting these molecules at sub-parts per million concentrations and at a wavelength resolution of less than 5 nm. The IL spectra were monitored to prevent severe damage to the samples. Furthermore, our IL system has the advantage that it is simple to add to a conventional micro-PIXE system.

  20. Quenching methods for background reduction in luminescence-based probe-target binding assays

    DOEpatents

    Cai, Hong; Goodwin, Peter M; Keller, Richard A.; Nolan, Rhiannon L.

    2007-04-10

    Background luminescence is reduced from a solution containing unbound luminescent probes, each having a first molecule that attaches to a target molecule and having an attached luminescent moiety, and luminescent probe/target adducts. Quenching capture reagent molecules are formed that are capable of forming an adduct with the unbound luminescent probes and having an attached quencher material effective to quench luminescence of the luminescent moiety. The quencher material of the capture reagent molecules is added to a solution of the luminescent probe/target adducts and binds in a proximity to the luminescent moiety of the unbound luminescent probes to quench luminescence from the luminescent moiety when the luminescent moiety is exposed to exciting illumination. The quencher capture reagent does not bind to probe molecules that are bound to target molecules and the probe/target adduct emission is not quenched.

  1. Laser-induced luminescence studies and crystal structure of the Europium(III) complex of 1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane. The link between phospate diester binding and catalysis by lanthanide(III) macrocyclic complexes

    SciTech Connect

    Amin, S.; Voss, D.A. Jr.; Lake, C.H.

    1995-06-07

    Solution and solid-state properties of the Eu(III) complex of the tetramide macrocyclic ligand TCMC (TCMC = 1,4,7,10-tetrakis(carbamoylmethyl)-1,4-7,10-tetraazacyclododecane) are investigated as part of an effort to develop lanthanide(III) macrocyclic catalysts. (Eu(TCMC)(H{sub 2}O))(CF{sub 3}SO{sub 3}){sub 3}{center_dot}2CH{sub 3}OH crystallizes in the centrosymmetric monoclinic space group. The structure was solved and refined to R=4.02% and R{sub w}=4.33% for 3510 reflections with F>6{omega}(F). (R=7.04%, R{sub w}=6.48% for all 5322 independent reflections). Four stereoisomers (two enantiomeric pairs) of the (Eu(TCMC)(H{sub 2}O)){sup 3+} cation appear in the crystal. The structure is disordered, containing two overlapping diastereomers that are interrelated by different conformations of the 1,4,7,10-tetraazacyclododecane ring defining the asymmetric unit. Two enantiomers are related to these by operations of the second king (i,n-glide). The nine-coordinate Eu(III) center has a 4:4:1 coordination geometry formed by the octadentate TCMC ligand and a single bound water molecule. The laser-induced luminescence excitation band of a single crystal of (Eu(TCMC)H{sub 2}O)(CF{sub 3}SO{sub 3}){sub 3}{center_dot}2CH{sub 3}OH resolves into two peaks, suggesting that each diastereomer gives rise to a separate excitation peak. Similarly, the luminescence excitation spectrum of a solution of (Eu(TCMC)){sup 3+} in water indicates that two species are present in solution. The {sup 31}P NMR resonance of diethyl phosphate is monitored at 18{+-}2{degrees}C, pH 7.4, upon addition of (Eu(TCMC)){sup 3+} as well as upon addition of several lanthanide(III) complexes that are catalysts for RNA cleavage. No binding of diethyl phosphate to (Eu(TCMC)){sup 3+} is observed. The hexadentate Schiff-base complex (La(L{sup 1})){sup 3+} binds to diethyl phosphate with a binding constant of 47.7{+-}0.5 M{sup -1}.

  2. Paper-based biodetection using luminescent nanoparticles.

    PubMed

    Ju, Qiang; Noor, M Omair; Krull, Ulrich J

    2016-05-10

    Point-of-care and in-field technologies for rapid, sensitive and selective detection of molecular biomarkers have attracted much interest. Rugged bioassay technology capable of fast detection of markers for pathogens and genetic diseases would in particular impact the quality of health care in the developing world, but would also make possible more extensive screening in developed countries to tackle problems such as those associated with water and food quality, and tracking of infectious organisms in hospitals and clinics. Literature trends indicate an increasing interest in the use of nanomaterials, and in particular luminescent nanoparticles, for assay development. These materials may offer attributes for development of assays and sensors that could achieve improvements in analytical figures of merit, and provide practical advantages in sensitivity and stability. There is opportunity for cost-efficiency and technical simplicity by implementation of luminescent nanomaterials as the basis for transduction technology, when combined with the use of paper substrates, and the ubiquitous availability of cell phone cameras and associated infrastructure for optical detection and transmission of results. Luminescent nanoparticles have been described for a broad range of bioanalytical targets including small molecules, oligonucleotides, peptides, proteins, saccharides and whole cells (e.g., cancer diagnostics). The luminescent nanomaterials that are described herein for paper-based bioassays include metal nanoparticles, quantum dots and lanthanide-doped nanocrystals. These nanomaterials often have broad and strong absorption and narrow emission bands that improve opportunity for multiplexed analysis, and can be designed to provide emission at wavelengths that are efficiently processed by conventional digital cameras. Luminescent nanoparticles can be embedded in paper substrates that are designed to direct fluid flow, and the resulting combination of technologies can offer

  3. Image analysis applied to luminescence microscopy

    NASA Astrophysics Data System (ADS)

    Maire, Eric; Lelievre-Berna, Eddy; Fafeur, Veronique; Vandenbunder, Bernard

    1998-04-01

    We have developed a novel approach to study luminescent light emission during migration of living cells by low-light imaging techniques. The equipment consists in an anti-vibration table with a hole for a direct output under the frame of an inverted microscope. The image is directly captured by an ultra low- light level photon-counting camera equipped with an image intensifier coupled by an optical fiber to a CCD sensor. This installation is dedicated to measure in a dynamic manner the effect of SF/HGF (Scatter Factor/Hepatocyte Growth Factor) both on activation of gene promoter elements and on cell motility. Epithelial cells were stably transfected with promoter elements containing Ets transcription factor-binding sites driving a luciferase reporter gene. Luminescent light emitted by individual cells was measured by image analysis. Images of luminescent spots were acquired with a high aperture objective and time exposure of 10 - 30 min in photon-counting mode. The sensitivity of the camera was adjusted to a high value which required the use of a segmentation algorithm dedicated to eliminate the background noise. Hence, image segmentation and treatments by mathematical morphology were particularly indicated in these experimental conditions. In order to estimate the orientation of cells during their migration, we used a dedicated skeleton algorithm applied to the oblong spots of variable intensities emitted by the cells. Kinetic changes of luminescent sources, distance and speed of migration were recorded and then correlated with cellular morphological changes for each spot. Our results highlight the usefulness of the mathematical morphology to quantify kinetic changes in luminescence microscopy.

  4. Roll Damping Characterisation Program: User Guide

    DTIC Science & Technology

    2014-06-01

    sallying test. The Defence Science and Technology Organisation (DSTO) have developed a software-based tool called the Roll Damping Characterisation...Murray Riding Maritime Division Murray obtained a Bachelor of Science (Honours) Degree from the

  5. Characterisation of nanomaterial hydrophobicity using engineered surfaces

    NASA Astrophysics Data System (ADS)

    Desmet, Cloé; Valsesia, Andrea; Oddo, Arianna; Ceccone, Giacomo; Spampinato, Valentina; Rossi, François; Colpo, Pascal

    2017-03-01

    Characterisation of engineered nanomaterials (NMs) is of outmost importance for the assessment of the potential risks arising from their extensive use. NMs display indeed a large variety of physico-chemical properties that drastically affect their interaction with biological systems. Among them, hydrophobicity is an important property that is nevertheless only slightly covered by the current physico-chemical characterisation techniques. In this work, we developed a method for the direct characterisation of NM hydrophobicity. The determination of the nanomaterial hydrophobic character is carried out by the direct measurement of the affinity of the NMs for different collectors. Each collector is an engineered surface designed in order to present specific surface charge and hydrophobicity degrees. Being thus characterised by a combination of surface energy components, the collectors enable the NM immobilisation with surface coverage in relation to their hydrophobicity. The experimental results are explained by using the extended DLVO theory, which takes into account the hydrophobic forces acting between NMs and collectors.

  6. Inhibition of Beta-Amyloid Fibrillation by Luminescent Iridium(III) Complex Probes.

    PubMed

    Lu, Lihua; Zhong, Hai-Jing; Wang, Modi; Ho, See-Lok; Li, Hung-Wing; Leung, Chung-Hang; Ma, Dik-Lung

    2015-09-30

    We report herein the application of kinetically inert luminescent iridium(III) complexes as dual inhibitors and probes of beta-amyloid fibrillogenesis. These iridium(III) complexes inhibited Aβ1-40 peptide aggregation in vitro, and protected against Aβ-induced cytotoxicity in neuronal cells. Furthermore, the complexes differentiated between the aggregated and unaggregated forms of Aβ1-40 peptide on the basis of their emission response.

  7. Inhibition of Beta-Amyloid Fibrillation by Luminescent Iridium(III) Complex Probes

    PubMed Central

    Lu, Lihua; Zhong, Hai-Jing; Wang, Modi; Ho, See-Lok; Li, Hung-Wing; Leung, Chung-Hang; Ma, Dik-Lung

    2015-01-01

    We report herein the application of kinetically inert luminescent iridium(III) complexes as dual inhibitors and probes of beta-amyloid fibrillogenesis. These iridium(III) complexes inhibited Aβ1–40 peptide aggregation in vitro, and protected against Aβ-induced cytotoxicity in neuronal cells. Furthermore, the complexes differentiated between the aggregated and unaggregated forms of Aβ1–40 peptide on the basis of their emission response. PMID:26419607

  8. Inhibition of Beta-Amyloid Fibrillation by Luminescent Iridium(III) Complex Probes

    NASA Astrophysics Data System (ADS)

    Lu, Lihua; Zhong, Hai-Jing; Wang, Modi; Ho, See-Lok; Li, Hung-Wing; Leung, Chung-Hang; Ma, Dik-Lung

    2015-09-01

    We report herein the application of kinetically inert luminescent iridium(III) complexes as dual inhibitors and probes of beta-amyloid fibrillogenesis. These iridium(III) complexes inhibited Aβ1-40 peptide aggregation in vitro, and protected against Aβ-induced cytotoxicity in neuronal cells. Furthermore, the complexes differentiated between the aggregated and unaggregated forms of Aβ1-40 peptide on the basis of their emission response.

  9. Luminescent liquid crystalline materials based on palladium(II) imine derivatives containing the 2-phenylpyridine core.

    PubMed

    Micutz, Marin; Iliş, Monica; Staicu, Teodora; Dumitraşcu, Florea; Pasuk, Iuliana; Molard, Yann; Roisnel, Thierry; Cîrcu, Viorel

    2014-01-21

    In this work we report our studies concerning the synthesis and characterisation of a series of imine derivatives that incorporate the 2-phenylpyridine (2-ppy) core. These derivatives were used in the cyclometalating reactions of platinum(II) or palladium(II) in order to prepare several complexes with liquid crystalline properties. Depending on the starting materials used as well as the solvents employed, different metal complexes were obtained, some of them showing both liquid crystalline behaviour and luminescence properties at room temperature. It was found that, even if there are two competing coordination sites, the cyclometalation process takes place always at the 2-ppy core with (for Pt) or without (for Pd) the imine bond cleavage. We successfully showed that it is possible to prepare emissive room temperature liquid crystalline materials based on double cyclopalladated heteroleptic complexes by varying the volume fraction of the long flexible alkyl tails on the ancillary benzoylthiourea (BTU) ligands.

  10. Luminescence and electrical properties of single ZnO/MgO core/shell nanowires

    SciTech Connect

    Grinblat, Gustavo; Comedi, David; Bern, Francis; Barzola-Quiquia, José; Esquinazi, Pablo; Tirado, Mónica

    2014-03-10

    To neutralise the influence of the surface of ZnO nanowires for photonics and optoelectronic applications, we have covered them with insulating MgO film and individually contacted them for electrical characterisation. We show that such a metal-insulator-semiconductor-type nanodevice exhibits a high diode ideality factor of 3.4 below 1 V. MgO shell passivates ZnO surface states and provides confining barriers to electrons and holes within the ZnO core, favouring excitonic ultraviolet radiative recombination, while suppressing defect-related luminescence in the visible and improving electrical conductivity. The results indicate the potential use of ZnO/MgO nanowires as a convenient building block for nano-optoelectronic devices.

  11. Tuning luminescence properties of silicon nanocrystals by lithium doping

    NASA Astrophysics Data System (ADS)

    Klimešová, E.; Kůsová, K.; Vacík, J.; Holý, V.; Pelant, I.

    2012-09-01

    Doping silicon nanocrystals (SiNCs) provides a new way to modify their luminescence properties and tailor them for a particular application. We prepared Li-doped SiNCs and characterized them by neutron depth profiling and x-ray diffraction. Our SiNC samples are doped with around 10-100 Li atoms per one nanocrystal and their lattice slightly expands after lithium insertion. We show that the photoluminescence (PL) properties of Li-doped SiNCs are distinctly modified compared to the undoped case. The PL maximum shifts to shorter wavelengths and the PL decay time decreases, both these features being favorable for applications in photonics. The spectral blue-shift is attributed to the tensile strain in SiNCs induced by doping with lithium.

  12. Luminescence and photoinduced absorption in ytterbium-doped optical fibres

    SciTech Connect

    Rybaltovsky, A A; Aleshkina, S S; Likhachev, M E; Bubnov, M M; Umnikov, A A; Yashkov, M V; Gur'yanov, Aleksei N; Dianov, Evgenii M

    2011-12-31

    Photochemical reactions induced in the glass network of an ytterbium-doped fibre core by IR laser pumping and UV irradiation have been investigated by analysing absorption and luminescence spectra. We have performed comparative studies of the photoinduced absorption and luminescence spectra of fibre preforms differing in core glass composition: Al{sub 2}O{sub 3} : SiO{sub 2}, Al{sub 2}O{sub 3} : Yb{sub 2}O{sub 3} : SiO{sub 2}, and P{sub 2}O{sub 5} : Yb{sub 2}O{sub 3} : SiO{sub 2}. The UV absorption spectra of unirradiated preform core samples show strong bands peaking at 5.1 and 6.5 eV, whose excitation plays a key role in photoinduced colour centre generation in the glass network. 'Direct' UV excitation of the 5.1- and 6.5-eV absorption bands at 244 and 193 nm leads to the reduction of some of the Yb{sup 3+} ions to Yb{sup 2+}. The photodarkening of ytterbium-doped fibres by IR pumping is shown to result from oxygen hole centre generation. A phenomenological model is proposed for the IR-pumping-induced photodarkening of ytterbium-doped fibres. The model predicts that colour centre generation in the core glass network and the associated absorption in the visible range result from a cooperative effect involving simultaneous excitation of a cluster composed of several closely spaced Yb{sup 3+} ions.

  13. Transmission electron microscopy characterisation of 0-D nanomaterials

    NASA Astrophysics Data System (ADS)

    Turner, Stuart Matthew

    When materials are scaled down to the nanometre level, a change in physical behaviour is frequently observed. In so-called 0-D nanomaterials (nanoparticles), these unique nanoscale properties are most abundant and are usually linked to either a change in (electronic) structure of the material or to the dominating influence of the particle surface at the nanometre scale. In this doctoral work the nanoscale properties of several nanoparticle systems have been studied using advanced transmission electron microscopy (TEM). Every material that was studied required for its solution a unique approach and a host of transmission electron microscopy techniques. The title of this doctoral work can be freely translated as "retrieving quantitatively the maximal and most accurate chemical, structural and morphological information from nanoparticles by advanced transmission electron microscopy, to uncover and explain their unique properties". Chapter 1 gives a brief general introduction to the world of nanomaterials and nanotechnology in general and more specifically to 0-D nanomaterials (nanoparticles). The unique properties and potential applications of these materials are described. The production of 0-D nanomaterials is not covered in this chapter, as this is an extremely broad field to cover in only a few pages. Instead, the production method for each of the materials is left to the detailed chapters that follow. In Chapter 2 the main transmission electron microscopy techniques used to characterise the materials in the further chapters are described together with the microscopes used to perform these techniques and their parameters of operation. Again, the sample-specific setups are listed in the detailed chapters that follow. Chapter 3 covers all work carried out on luminescent detonation nanodiamond powder for drug delivery and bio-medical imaging applications. Specific attention is paid to the morphology, surface chemistry and nitrogen incorporation of detonation

  14. Luminescent amino-functionalized or erbium-doped silica spheres for biological applications.

    PubMed

    Enrichi, Francesco

    2008-01-01

    This work presents the morphological and optical properties of luminescent silica spheres, discussing applications in bioimaging and biosensing. The spheres are obtained by the hydrolysis and condensation of tetraethylorthosilicate (TEOS) and can be synthesized by following either a basic or an acidic route. Luminescence emission is induced after incorporation of aminopropyltriethoxysilane (APTES) during synthesis or by introducing an optically active element, such as erbium, or other rare-earth elements. The luminescence properties of APTES-functionalized silica spheres have been investigated and optimized by varying the annealing temperature. On the other hand, erbium incorporation in silica spheres was also studied and the corresponding Er(3+) luminescence emission at 1.54 microm was evaluated for intensity and lifetime. The basic pH environment in the synthesis allows good control of the size of the spheres (approximately 200 nm in diameter), whereas the acidic route produces a wide dispersion in particle size (200-5000 nm). Both these approaches, however, can be followed to obtain an efficient photoluminescence (PL) emission for the APTES-functionalized silica spheres after 400-600 degrees C thermal treatment. If Er(NO(3))(3) is introduced in the basic solution, a rapid precipitation of Er(OH)(3) occurs, but erbium can be easily and efficiently incorporated in the acid-synthesized spheres, showing high PL intensity at 1.54 microm with lifetime of 3.9 ms. Finally, I discuss perspectives for the applications of these luminescent silica spheres, in particular as biological markers for bioimaging and biosensing.

  15. Semiconducting polymer encapsulated mesoporous silica particles with conjugated Europium complexes: toward enhanced luminescence under aqueous conditions.

    PubMed

    Zhang, Jixi; Prabhakar, Neeraj; Näreoja, Tuomas; Rosenholm, Jessica M

    2014-01-01

    Immobilization of lanthanide organic complexes in meso-organized hybrid materials for luminescence applications have attracted immense interest due to the possibility of controlled segregation at the nanoscopic level for novel optical properties. Aimed at enhancing the luminescence intensity and stability of the hybrid materials in aqueous media, we developed polyvinylpyrrolidone (PVP) stabilized, semiconducting polymer (poly(9-vinylcarbazole), PVK) encapsulated mesoporous silica hybrid particles grafted with Europium(III) complexes. Monosilylated β-diketonate ligands (1-(2-naphthoyl)-3,3,3-trifluoroacetonate, NTA) were first co-condensed in the mesoporous silica particles as pendent groups for bridging and anchoring the lanthanide complexes, resulting in particles with an mean diameter of ∼ 450 nm and a bimodal pore size distribution centered at 3.5 and 5.3 nm. PVK was encapsulated on the resulted particles by a solvent-induced surface precipitation process, in order to seal the mesopores and protect Europium ions from luminescence quenching by producing a hydrophobic environment. The obtained polymer encapsulated MSN-EuLC@PVK-PVP particles exhibit significantly higher intrinsic quantum yield (Φ(Ln) = 39%) and longer lifetime (τ(obs) = 0.51 ms), as compared with those without polymer encapsulation. Most importantly, a high luminescence stability was realized when MSN-EuLC@PVK-PVP particles were dispersed in various aqueous media, showing no noticeable quenching effect. The beneficial features and positive attributes of both mesoporous silica and semiconducting polymers as lanthanide-complex host were merged in a single hybrid carrier, opening up the possibility of using these hybrid luminescent materials under complex aqueous conditions such as biological/physiological environments.

  16. Turn-on persistent luminescence probe based on graphitic carbon nitride for imaging detection of biothiols in biological fluids.

    PubMed

    Tang, Yurong; Song, Hongjie; Su, Yingying; Lv, Yi

    2013-12-17

    Herein, we present a novel strategy based on a "turn-on" persistent luminescence imaging chemical system of graphitic carbon nitride for detecting biothiols in biological fluids. Graphitic carbon nitride (g-C3N4) as persistent luminescence probe is fabricated via a new procedure based on pyrolysis of guanidine hydrochloride under ambient atmospheric conditions. The prepared g-C3N4 nanosheets give intensively long-persistent luminescence that can avoid interference from biological media such as tissue autofluorescence and scattering light. The original persistent luminescence of g-C3N4 turns off due to the adsorption of silver ion (Ag(+)) onto g-C3N4 materials with an electron transfer process. The presence of biothiols induces the onset of persistent luminescence emission by interrupting the quenching interaction, thereby turning on the imaging probe. The approach exhibits high specificity and high sensitivity to biothiols with low detection limit for cysteine (Cys), homocysteine (Hcy), and glutathione (GSH) with 6.4, 8.1, and 9.6 nM, respectively. It is also successfully applied for imaging detection of biothiols in human urine, plasma, and cell lysates, demonstrating its great value of practical application in biological systems.

  17. Influence of charge transfer state on Eu3+ luminescence in LaAlO3, by high pressure spectroscopy

    NASA Astrophysics Data System (ADS)

    Behrendt, Mirosław; Mahlik, Sebastian; Grinberg, Marek; Stefańska, Dagmara; Dereń, Przemysław J.

    2017-01-01

    The contribution presents spectroscopic characterization of LaAlO3 doped with 0.5 mol %. Eu3+. We measured steady state luminescence, luminescence excitation spectra, as well as the time resolved spectra and luminescence kinetics. The experiments were performed at high hydrostatic pressure applied in diamond anvil cell (DAC) which was changed from ambient to 250 kbar. We found that for all pressures the emission from the 5D0 and 5D1 excited emitting state of Eu3+ was delayed in time after excitation pulse whilst emission from the 5D2 appear immediately after excitation. At pressure above 12 kbar the strong magnification of the luminescence lines related to the transitions from the 5D3 state which were very weak at ambient condition is observed. The emission decay of the 5D3 luminescence become slower when pressure is increased. All these effects are attributed to pressure-induced increase of the energy of the ground electronic configuration 4f6 of the Eu2+ with respect to the valence band edge which results in the charge transfer state, and 5D3 level crossing.

  18. Magnetic tuning of upconversion luminescence in Au/NaGdF4:Yb(3+)/Er(3+) nanocomposite.

    PubMed

    Dai, Gangtao; Zhong, Zhiqiang; Wu, Xiaofeng; Zhan, Shiping; Hu, Shigang; Hu, Pan; Hu, Junshan; Wu, Shaobing; Han, Junbo; Liu, Yunxin

    2017-04-18

    Lanthanide-doped upconversion nanoparticles (UCNPs) NaGdF4:Yb(3+)/Er(3+) have received increasing attention due to their unique optical-magnetic bifunctional properties. Here, we show that the luminescent intensity from NaGdF4:Yb(3+)/Er(3+) nanoparticles decreases monotonously with increasing the applied magnetic field from 0 to 37.1 T, while plasmon-enhanced upconversion luminescence in Au/NaGdF4:Yb(3+)/Er(3+) nanocomposite is independent of a magnetic field lower than 6 T. The surface plasmon resonances could compensate for the energetic mismatching between the excitation light and the energy-level gaps induced by magnetic field and enhance the radiative efficiency, which is the main factor for achieving this stable upconversion emission in this nanocomposite under a magnetic field not higher than 6 T. These findings provide a novel route for exploring the magnetic control of upconversion luminescence in lanthanide-doped bifunctional nanoparticles.

  19. Magnetic tuning of upconversion luminescence in Au/NaGdF4:Yb3+/Er3+ nanocomposite

    NASA Astrophysics Data System (ADS)

    Dai, Gangtao; Zhong, Zhiqiang; Wu, Xiaofeng; Zhan, Shiping; Hu, Shigang; Hu, Pan; Hu, Junshan; Wu, Shaobing; Han, Junbo; Liu, Yunxin

    2017-04-01

    Lanthanide-doped upconversion nanoparticles (UCNPs) NaGdF4:Yb3+/Er3+ have received increasing attention due to their unique optical-magnetic bifunctional properties. Here, we show that the luminescent intensity from NaGdF4:Yb3+/Er3+ nanoparticles decreases monotonously with increasing the applied magnetic field from 0 to 37.1 T, while plasmon-enhanced upconversion luminescence in Au/NaGdF4:Yb3+/Er3+ nanocomposite is independent of a magnetic field lower than 6 T. The surface plasmon resonances could compensate for the energetic mismatching between the excitation light and the energy-level gaps induced by magnetic field and enhance the radiative efficiency, which is the main factor for achieving this stable upconversion emission in this nanocomposite under a magnetic field not higher than 6 T. These findings provide a novel route for exploring the magnetic control of upconversion luminescence in lanthanide-doped bifunctional nanoparticles.

  20. Time-resolved synchrotron radiation excited optical luminescence: light-emission properties of silicon-based nanostructures.

    PubMed

    Sham, Tsun-Kong; Rosenberg, Richard A

    2007-12-21

    The recent advances in the study of light emission from matter induced by synchrotron radiation: X-ray excited optical luminescence (XEOL) in the energy domain and time-resolved X-ray excited optical luminescence (TRXEOL) are described. The development of these element (absorption edge) selective, synchrotron X-ray photons in, optical photons out techniques with time gating coincide with advances in third-generation, insertion device based, synchrotron light sources. Electron bunches circulating in a storage ring emit very bright, widely energy tunable, short light pulses (<100 ps), which are used as the excitation source for investigation of light-emitting materials. Luminescence from silicon nanostructures (porous silicon, silicon nanowires, and Si-CdSe heterostructures) is used to illustrate the applicability of these techniques and their great potential in future applications.

  1. Anti-Stokes shift luminescent materials for bio-applications.

    PubMed

    Zhu, Xingjun; Su, Qianqian; Feng, Wei; Li, Fuyou

    2017-02-20

    Anti-Stokes shift luminescence is a special optical process, which converts long-wavelength excitation to short-wavelength emission. This unique ability is especially helpful for bio-applications, because the longer-wavelength light source, usually referring to near infrared light, has a larger penetration depth offering a longer working distance for in vivo applications. The anti-Stokes shift luminescence signal can also be distinguished from the auto-fluorescence of biological tissues, thus reducing background interference during bioimaging. Herein, we summarize recent advances in anti-Stokes shift luminescent materials, including lanthanide and triplet-triplet-annihilation-based upconversion nanomaterials, and newly improved hot-band absorption-based luminescent materials. We focus on the synthetic strategies, optical optimization and biological applications as well as present comparative discussions on the luminescence mechanisms and characteristics of these three types of luminescent materials.

  2. Luminescence quenching of Dy3+ ions in lead bismuthate glasses

    NASA Astrophysics Data System (ADS)

    Pisarski, Wojciech A.; Pisarska, Joanna; Lisiecki, Radosław; Dominiak-Dzik, Grażyna; Ryba-Romanowski, Witold

    2012-04-01

    Luminescence of lead bismuthate glasses PbO-Bi2O3-Ga2O3 containing Dy3+ ions has been studied. Two overlapping luminescence bands corresponding to 3P1-1S0 transition of Bi3+ and 4F9/2 -6H13/2 transition of Dy3+ were detected under 480 nm excitation. Comparison of luminescence features for the system under study to those reported for dysprosium-doped lead borate glass PbO-B2O3-Ga2O3 indicates that the luminescence of Dy3+ is efficiently quenched by Bi3+ ions. Analysis of luminescence dynamics implies that the excitation energy transfer from Dy3+ to Bi3+ is nonradiative. The theoretical calculations using Inokuti-Hirayama model confirm strong luminescence of Dy3+ ions in lead bismuthate glasses.

  3. Luminescence properties of a nanoporous freshwater diatom.

    PubMed

    Goswami, Bondita; Choudhury, Amarjyoti; Buragohain, Alak K

    2012-01-01

    Freshwater diatom frustules show special optical properties. In this paper we observed luminescence properties of the freshwater diatom Cyclotella meneghiniana. To confirm the morphological properties we present scanning electron microscopy (SEM) images. X-ray diffraction (XRD) studies were carried out to visualize the structural properties of the frustules, confirming that silica present in diatom frustules crystallizes in an α-quartz structure. Study of the optical properties of the silica frustules of diatoms using ultra-violet-visible (UV-vis) spectroscopy and photoluminescence spectroscopy confirmed that the diatom C. meneghiniana shows luminescence in the blue region of the electromagnetic spectrum when irradiated with UV light. This property of diatoms can be exploited to obtain many applications in day-to-day life. Also, using time-resolved photoluminescence spectroscopy (TRPL) it was confirmed that this species of diatom shows bi-exponential decay.

  4. Luminescent lanthanide chelates and methods of use

    SciTech Connect

    Selvin, Paul R.; Hearst, John

    1997-01-01

    The invention provides lanthanide chelates capable of intense luminescence. The celates comprise a lanthanide chelator covalently joined to a coumarin-like or quinolone-like sensitizer. Exemplary sensitzers include 2- or 4-quinolones, 2- or 4-coumarins, or derivatives thereof e.g. carbostyril 124 (7-amino-4-methyl-2-quinolone), coumarin 120 (7-amino-4-methyl-2-coumarin), coumarin 124 (7-amino-4-(trifluoromethyl)-2-coumarin), aminomethyltrimethylpsoralen, etc. The chelates form high affinity complexes with lanthanides, such as terbium or europium, through chelator groups, such as DTPA. The chelates may be coupled to a wide variety of compounds to create specific labels, probes, diagnostic and/or therapeutic reagents, etc. The chelates find particular use in resonance energy transfer between chelate-lanthanide complexes and another luminescent agent, often a fluorescent non-metal based resonance energy acceptor. The methods provide useful information about the structure, conformation, relative location and/or interactions of macromolecules.

  5. Luminescence properties of silicon-cellulose nanocomposite

    NASA Astrophysics Data System (ADS)

    Pikulev, Vitaly; Loginova, Svetlana; Gurtov, Valery

    2012-07-01

    We have characterized the structure and luminescence properties for two-component material composed of nanocrystalline cellulose and nanocrystalline (less to 100 nm) silicon powder. An efficient and stable photoluminescence of nanocomposite, resistant to the influence of gas-phase oxidants, has been found. The obtained material has electret-like properties and demonstrates the possibility of multiple-recharging in an electric field near 5·103 V/cm at temperatures ranging from -70°C to 100°C. The presence of the electric field, as well as ozone or low-temperature plasma treatment, does not change the luminescence spectrum due to quantum size properties of silicon nanoparticles. We believe that these particles may appear in two states: both embedded in a cellulose matrix and in the form of mechanical mixture.

  6. Anomalous enhancement of nanodiamond luminescence upon heating

    NASA Astrophysics Data System (ADS)

    Khomich, A. A.; Kudryavtsev, O. S.; Dolenko, T. A.; Shiryaev, A. A.; Fisenko, A. V.; Konov, V. I.; Vlasov, I. I.

    2017-02-01

    Characteristic photoluminescence (PL) of nanodiamonds (ND) of different origin (detonation, HPHT, extracted from meteorite) was studied in situ at high temperatures in the range 20-450 °C. Luminescence was excited using 473 nm laser and recorded in the range 500-800 nm. In contrast to decrease of point defect PL in bulk diamond with temperature, we found that the ND luminescence related to ND surface defects increases almost an order of magnitude upon heating to 200-250 °C. The observed effect reveals that water adsorbed on ND surfaces efficiently quenches PL; water desorption on heating leads to dramatic increase of the radiative de-excitation.

  7. Method and apparatus for reducing solvent luminescence background emissions

    DOEpatents

    Affleck, Rhett L.; Ambrose, W. Patrick; Demas, James N.; Goodwin, Peter M.; Johnson, Mitchell E.; Keller, Richard A.; Petty, Jeffrey T.; Schecker, Jay A.; Wu, Ming

    1998-01-01

    The detectability of luminescent molecules in solution is enhanced by reducing the background luminescence due to impurity species also present in the solution. A light source that illuminates the solution acts to photolyze the impurities so that the impurities do not luminesce in the fluorescence band of the molecule of interest. Molecules of interest may be carried through the photolysis region in the solution or may be introduced into the solution after the photolysis region.

  8. Method and apparatus for reducing solvent luminescence background emissions

    DOEpatents

    Affleck, R.L.; Ambrose, W.P.; Demas, J.N.; Goodwin, P.M.; Johnson, M.E.; Keller, R.A.; Petty, J.T.; Schecker, J.A.; Wu, M.

    1998-10-27

    The detectability of luminescent molecules in solution is enhanced by reducing the background luminescence due to impurity species also present in the solution. A light source that illuminates the solution acts to photolyze the impurities so that the impurities do not luminesce in the fluorescence band of the molecule of interest. Molecules of interest may be carried through the photolysis region in the solution or may be introduced into the solution after the photolysis region. 6 figs.

  9. Thermally stimulated luminescence of urine salts

    NASA Astrophysics Data System (ADS)

    Bordun, O.; Drobchak, O.

    2008-05-01

    The thermally stimulated luminescence (TSL) of normal and pathological urine was studied. The presence of pathological salts leads to extinguishing of TSL intensity and to the appearance of additional stripes with maxima nearly 118 and 205K, except of characteristic stripes with the maxima nearly 173 and 260K. TSL stripes depend on urine constituents. The comparison of TSL intensity of normal and pathological urine is carried out and energies of thermal activation are determined for most intensive TSL stripes.

  10. Thermal History Using Microparticle Trap Luminescence

    DTIC Science & Technology

    2012-06-01

    RESULTS 4.1 4.2 4.3 4.4 4.5 4.6 4.7 Thermoluminescence Testing and Apparatus Samples Materials Synthesis Equipment Modeling the Effect of...Testing of Luminescent Particles in Explosions Pulsed Thermoluminescence 5. CONCLUSIONS HDTRA1-07-1 -0016 University of Minnesota (Twin Cities...arbitrary profiles. Among the successfu l concept demonstrations was one using Mg2Si04:Tb,Co particles with two thermoluminescent peaks heated over

  11. Luminescence of erbium ions in tellurite glasses

    SciTech Connect

    Savikin, Alexander P.; Grishin, Igor A.; Sharkov, Valery V.; Budruev, Andrei V.

    2013-11-15

    Optical characteristics of new generation of tellurite glasses having high stability against crystallization have been studied. As the initial reagents for the glasses synthesis on the base of tellurium oxide (TeO{sub 2}) there were used such oxides as WO{sub 3}, MoO{sub 3}, La{sub 2}O{sub 3}, Li{sub 2}CO{sub 3}, ZnO—Bi{sub 2}O{sub 2}CO{sub 3} and active components such as high purity Er{sub 2}O{sub 3}, Yb{sub 2}O{sub 3}, ErF{sub 3} and YbF{sub 3}. Intensities of luminescence at 1.53 µm of the erbium ions were determined after excitation at 975 nm. Experimental data obtained have shown the possibility to use the studied glasses doped by Er{sup 3+} and Yb{sup 3+} as active elements for fiber and integrated optics. - Graphical abstract: In contrast to the case of ZBLAN glass the TeO{sub 2}–WO{sub 3} (Er{sup 3+}) glass has bright intensity of luminescence at 1.53 µm for erbium ions that should be caused by excitation at 975 nm. Experimental data obtained have shown the possibility to use the studied glasses doped by Er{sup 3+} and Yb{sup 3+} as active elements for fiber and integrated optics. Display Omitted - Highlights: • We examined changes in growth of luminescence in doubly-doped tellurite glasses. • We found that luminescence grows in two orders by using Er{sup 3+} and Yb{sup 3+} at 1.53 μm. • We see possibility to use those glasses as active elements for integrated optics.

  12. Luminescent probes for optical in vivo imaging

    NASA Astrophysics Data System (ADS)

    Texier, Isabelle; Josserand, Veronique; Garanger, Elisabeth; Razkin, Jesus; Jin, Zhaohui; Dumy, Pascal; Favrot, Marie; Boturyn, Didier; Coll, Jean-Luc

    2005-04-01

    Going along with instrumental development for small animal fluorescence in vivo imaging, we are developing molecular fluorescent probes, especially for tumor targeting. Several criteria have to be taken into account for the optimization of the luminescent label. It should be adapted to the in vivo imaging optical conditions : red-shifted absorption and emission, limited overlap between absorption and emission for a good signal filtering, optimized luminescence quantum yield, limited photo-bleaching. Moreover, the whole probe should fulfill the biological requirements for in vivo labeling : adapted blood-time circulation, biological conditions compatibility, low toxicity. We here demonstrate the ability of the imaging fluorescence set-up developed in LETI to image the bio-distribution of molecular probes on short times after injection. Targeting with Cy5 labeled holo-transferrin of subcutaneous TS/Apc (angiogenic murine breast carcinoma model) or IGROV1 (human ovarian cancer) tumors was achieved. Differences in the kinetics of the protein uptake by the tumors were evidenced. IGROV1 internal metastatic nodes implanted in the peritoneal cavity could be detected in nude mice. However, targeted metastatic nodes in lung cancer could only be imaged after dissection of the mouse. These results validate our fluorescence imaging set-up and the use of Cy5 as a luminescent label. New fluorescent probes based on this dye and a molecular delivery template (the RAFT molecule) can thus be envisioned.

  13. Dislocation luminescence in GaN single crystals under nanoindentation

    PubMed Central

    2014-01-01

    This work presents an experimental study on the dislocation luminescence in GaN by nanoindentation, cathodoluminescence, and Raman. The dislocation luminescence peaking at 3.12 eV exhibits a series of special properties in the cathodoluminescence measurements, and it completely disappears after annealing at 500°C. Raman spectroscopy shows evidence for existence of vacancies in the indented region. A comprehensive investigation encompassing cathodoluminescence, Raman, and annealing experiments allow the assignment of dislocation luminescence to conduction-band-acceptor transition involving Ga vacancies. The nanoscale plasticity of GaN can be better understood by considering the dislocation luminescence mechanism. PMID:25593548

  14. Tuning luminescence and reducing reabsorption of CdSe quantum disks for luminescent solar concentrators

    NASA Astrophysics Data System (ADS)

    Lin, Huichuan; Xie, Peng; Liu, Yong; Zhou, Xiang; Li, Baojun

    2015-08-01

    Cadmium selenide (CdSe) quantum disks (QDs) have been synthesized for application in luminescent solar concentrators (LSCs). Luminescence tuning and reabsorption reduction of the QDs were achieved by controlling their size using a hot injection method. The overlap of the absorption and photoluminescence spectra of the as-prepared CdSe QDs was negligible. The as-prepared CdSe QDs were incorporated into polymethylmethacrylate without aggregation and luminescence quenching. The obtained highly transparent composites with non-affecting light-emitting properties were used as LSCs. The placement of a CdSe QDs doped LSC prototype (10 × 1 × 0.1 cm) on a Si-cell resulted in a 201% increase in the electrical power output of the Si-cell compared with that of the bare Si-cell.

  15. Optically Stimulated Luminescence (OSL) of dental enamel for retrospective assessment of radiation exposure

    PubMed Central

    Yukihara, E.G.; Mittani, J.; McKeever, S.W.S.; Simon, S.L.

    2009-01-01

    This paper briefly reviews the optically stimulated luminescence (OSL) properties of dental enamel and discusses the potential and challenges of OSL for filling the technology gap in biodosimetry required for medical triage following a radiological/nuclear accident or terrorist event. The OSL technique uses light to stimulate a radiation-induced luminescence signal from materials previously exposed to ionizing radiation. This luminescence originates from radiation-induced defects in insulating crystals and is proportional to the absorbed dose of ionizing radiation. In our research conducted to date, we focused on fundamental investigations of the OSL properties of dental enamel using extracted teeth and tabletop OSL readers. The objective was to obtain information to support the development of the necessary instrumentation for retrospective dosimetry using dental enamel in laboratory, or for in situ and non-invasive accident dosimetry using dental enamel in emergency triage. An OSL signal from human dental enamel was detected using blue, green, or IR stimulation. Blue/green stimulation associated with UV emission detection seems to be the most appropriate combination in the sense that there is no signal from un-irradiated samples and the shape of the OSL decay is clear. Improvements in the minimum detection level were achieved by incorporating an ellipsoidal mirror in the OSL system to maximize light collection. Other possibilities to improve the sensitivity and research steps necessary to establish the feasibility of the technique for retrospective assessment of radiation exposure are also discussed. PMID:19623269

  16. Optically Stimulated Luminescence (OSL) of dental enamel for retrospective assessment of radiation exposure.

    PubMed

    Yukihara, E G; Mittani, J; McKeever, S W S; Simon, S L

    2007-07-01

    This paper briefly reviews the optically stimulated luminescence (OSL) properties of dental enamel and discusses the potential and challenges of OSL for filling the technology gap in biodosimetry required for medical triage following a radiological/nuclear accident or terrorist event. The OSL technique uses light to stimulate a radiation-induced luminescence signal from materials previously exposed to ionizing radiation. This luminescence originates from radiation-induced defects in insulating crystals and is proportional to the absorbed dose of ionizing radiation. In our research conducted to date, we focused on fundamental investigations of the OSL properties of dental enamel using extracted teeth and tabletop OSL readers. The objective was to obtain information to support the development of the necessary instrumentation for retrospective dosimetry using dental enamel in laboratory, or for in situ and non-invasive accident dosimetry using dental enamel in emergency triage. An OSL signal from human dental enamel was detected using blue, green, or IR stimulation. Blue/green stimulation associated with UV emission detection seems to be the most appropriate combination in the sense that there is no signal from un-irradiated samples and the shape of the OSL decay is clear. Improvements in the minimum detection level were achieved by incorporating an ellipsoidal mirror in the OSL system to maximize light collection. Other possibilities to improve the sensitivity and research steps necessary to establish the feasibility of the technique for retrospective assessment of radiation exposure are also discussed.

  17. A new luminescence beam profile monitor for intense proton and heavy ion beams

    SciTech Connect

    Tsang,T.; Bellavia, S.; Connolly, R.; Gassner, D.; Makdisi, Y.; Russo, T.; Thieberger, P.; Trbojevic, D.; Zelenski, A.

    2008-10-01

    A new luminescence beam profile monitor is realized in the polarized hydrogen gas jet target at the Relativistic Heavy Ion Collider (RHIC) facility. In addition to the spin polarization of the proton beam being routinely measured by the hydrogen gas jet, the luminescence produced by beam-hydrogen excitation leads to a strong Balmer series lines emission. A selected hydrogen Balmer line is spectrally filtered and imaged to produce the transverse RHIC proton beam shape with unprecedented details on the RHIC beam profile. Alternatively, when the passage of the high energy RHIC gold ion beam excited only the residual gas molecules in the beam path, sufficient ion beam induced luminescence is produced and the transverse gold ion beam profile is obtained. The measured transverse beam sizes and the calculated emittances provide an independent confirmation of the RHIC beam characteristics and to verify the emittance conservation along the RHIC accelerator. This optical beam diagnostic technique by making use of the beam induced fluorescence from injected or residual gas offers a truly noninvasive particle beam characterization, and provides a visual observation of proton and heavy ion beams. Combined with a longitudinal bunch measurement system, a 3-dimensional spatial particle beam profile can be reconstructed tomographically.

  18. Luminescent AIE materials for high-performance sensing applications

    NASA Astrophysics Data System (ADS)

    Leung, Chris Wai Tung; Tang, Ben Zhong

    2014-10-01

    Luminescent materials have been widely applied in chemo- and bio-sensing applications because these luminescent materials offer high signal-to-background ratio, superior sensitivity and broad dynamic ranges in various detections. Conventional luminogens suffer from aggregation-caused quenching (ACQ) effect due to strong π-π stacking interaction upon aggregate formation of the luminogens with analytes. Such ACQ effect limits the scope of practical sensing applications. Luminogens with aggregation-induced emission (AIE) characteristics enjoy high emission efficiency in solid or aggregated state while they are non-emissive in solution. AIE luminogens (AIEgens) tackle the lethal problem of ACQ materials in the sensing applications. Siloles and tetraphenylethene (TPE) are archetypal AIE cores and possess advantages of facile synthesis and readily functionalization. AIEgens have been utilized to develop various fluorescent chemosensors. For example, hyperbranched AIE polymers with different topologies can be worked as turn-off explosive sensor with high sensitivity. The explosive detections can be done in solid film, which facilitates practical usage. The AIEgens can also be used as sensors for volatile organic compounds and metal ions through alternating fluorescence on/off mechanisms. Besides chemosensor, the AIEgens have been applied in the fields of biology. Water-soluble AIEgens have been developed for quantifying nucleic acids and proteins. They can serve as bioprobes for real-time monitoring and studying the kinetic of protein conformational changes, making them promising for diagnostic and therapeutic applications. These demonstrations significantly expand the scope of analysis applications of AIEgens and offer new strategies to the design of new fluorescent chemo- and bio-sensors.

  19. Circularly Polarized Luminescence from Helically Chiral N,N,O,O‐Boron‐Chelated Dipyrromethenes

    PubMed Central

    Alnoman, Rua B.; Rihn, Sandra; O'Connor, Daniel C.; Black, Fiona A.; Costello, Bernard; Waddell, Paul G.; Clegg, William; Peacock, Robert D.; Herrebout, Wouter

    2015-01-01

    Abstract Helically chiral N,N,O,O‐boron chelated dipyrromethenes showed solution‐phase circularly polarized luminescence (CPL) in the red region of the visible spectrum (λ em(max) from 621 to 663 nm). The parent dipyrromethene is desymmetrised through O chelation of boron by the 3,5‐ortho‐phenolic substituents, inducing a helical chirality in the fluorophore. The combination of high luminescence dissymmetry factors (|g lum| up to 4.7 ×10−3) and fluorescence quantum yields (Φ F up to 0.73) gave exceptionally efficient circularly polarized red emission from these simple small organic fluorophores, enabling future application in CPL‐based bioimaging. PMID:26555772

  20. Unusual method for phenolic hydroxyl bridged lanthanide CPs: syntheses, characterization, one and two photon luminescence.

    PubMed

    Zeng, Cheng-Hui; Zhao, Fu-Li; Yang, Yang-Yi; Xie, Ming-Yuan; Ding, Xue-Mei; Hou, De-Jian; Ng, Seik Weng

    2013-02-14

    A "basophilic method" for phenolic hydroxyl bridged lanthanide coordination polymers (CPs) was developed. With this method, eleven CPs with the general formula of [Ln(HL1)L1·H(2)O](n) (Ln = Tb (1), Nd (2), Eu (3), Gd (4), La (5), Er (6), Y (7), H(2)L1 = 4-methyl salicylic acid) and [Ln(HL2)L2·2MeOH](n) (Ln = Eu (8), Tb (9), Gd (10), La (11), H(2)L2 = 3-hydroxy-2-naphthoic acid) were synthesized based on two ligands, and five of them (1-4 and 8) were characterised by X-ray single crystal diffraction. The powder X-ray diffraction patterns (PXRD) of complexes showed that 1-7 are isostructural, 8-11 are isostructural. Furthermore, 1 was characterised by Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), differential thermal analysis (DTA), elemental analysis (EA), one and two photon luminescence were investigated in detail.

  1. Characterising insomnia: A graph spectral theory approach.

    PubMed

    Chaparro-Vargas, Ramiro; Ahmed, Beena; Penzel, Thomas; Cvetkovic, Dean

    2015-01-01

    This paper introduces a computational approach to characterise healthy controls and insomniacs based on graph spectral theory. Based upon expert-generated hypnograms of sleep onset periods, a network of sleep stages transitions is derived to compute four similarity distances amongst subjects' sleeping patterns. A subsequent statistical analysis is performed to differentiate the 16-subject healthy group from a 16-patient disordered cohort. Our findings demonstrated that the similarity distances based on eigenvalues determination, i.e. d1 and d4 were the most reliable and robust measures to characterise insomniacs, discriminating 93% and 87% of the affected population, respectively.

  2. Understanding the interaction between trivalent lanthanide ions and stereoregular polymethacrylates through luminescence, binding isotherms, NMR, and interaction with cetylpyridinium chloride.

    PubMed

    Kogej, Ksenija; Fonseca, Sofia M; Rovisco, José; Azenha, M Emília; Ramos, M Luísa; Seixas de Melo, J Sérgio; Burrows, Hugh D

    2013-11-26

    Complexation of isotactic, syndiotactic, and atactic poly(methacrylic acid), PMA, with trivalent lanthanide ions has been studied in water at a degree of neutralization 0.5. Metal ion binding is shown by quenching of cerium(III) fluorescence, enhancement of Tb(III) luminescence, and lanthanide-induced line broadening in the PMA (1)H NMR spectra. Comparison with lanthanide-acetate complexation suggests carboxylate binds in a bidentate fashion, while Ce(III) luminescence quenching suggests an ≈3:1 carboxylate:metal ion stoichiometry, corresponding to charge neutralization. The presence of both free and bound Ce(III) cations in PMA solutions is confirmed from luminescence decays. Studies of Tb(3+) luminescence lifetime in H2O and D2O solutions show complexation is accompanied by loss of 5-6 water molecules, indicating that each bidentate carboxylate replaces two coordinated water molecules. The behavior depends on pH and polyelectrolyte stereoregularity, and stronger binding is observed with isotactic polyelectrolyte. Binding of cetylpyridinium chloride, CPC, in these systems is studied by luminescence, NMR, and potentiometry. NMR and Tb(3+) luminescence lifetime studies show the strongest binding with the isotactic polymer. Binding of surfactant to poly(methacrylate) in the presence of lanthanides is noncooperative, i.e., it binds to the free sites; binding isotherms in the presence of lanthanides are shifted to higher free surfactant concentrations, compared with sodium ions, have lower slopes and show a clear two-step binding mechanism. While CPC readily replaces the Na(+) ions of poly(methacrylate) and binds very strongly (low critical association concentrations), exchange is much more difficult with the strongly bound trivalent lanthanide ions. Effects of tacticity are seen, with surfactant interacting most strongly with isotactic chains in the initial stages of binding, while in the final stages of binding the interaction is strongest with atactic poly(methacrylate).

  3. [Effect of salts on luminescence of natural and recombinant luminescent bacterial biosensors].

    PubMed

    Deriabin, D G; Aleshina, E S

    2008-01-01

    Effect of cations K+, Na+, Mg2+, and Ca2+ and anions SO4(2-), HCO3(-), and CO3(2-) on the luminescence intensity of the marine luminescent bacterium Photobacterium phorphoreum (Microbiosensor B-17 677f) and the recombinant strain Escherichia coli with cloned lux operon of P. leiognathi (Ekolyum-9). It is found that small concentrations of chlorides and sulfates of the cations studied had a concentration-dependent stimulatory effect on bacterial bioluminescence; as the concentration of agents increased, activation was succeeded by quenching. The strength of the inhibitory effect, which is characterized by EC50, decreased in the series Ca2+ > Na+ > Mg2+ > K+. Carbonates and hydrocarbonates had a pronounced inhibitory effect on the bioluminescence intensity, determined by an increase in pH. We showed that some types of highly mineralized water with a high hydrocarbonate content have a marked inhibitory effect on the luminescence intensity of microbial luminescent biosensors, mimicking the effect of chemical pollutants.

  4. Electroluminescent apparatus having a structured luminescence conversion layer

    DOEpatents

    Krummacher, Benjamin Claus

    2008-09-02

    An apparatus such as a light source is disclosed which has an OLED device and a structured luminescence conversion layer disposed on the substrate or transparent electrode of said OLED device and on the exterior of said OLED device. The structured luminescence conversion layer contains color-changing and non-color-changing regions arranged in a particular pattern.

  5. Measuring Carrier Lifetime in GaAs by Luminescence

    NASA Technical Reports Server (NTRS)

    Von Roos, O.

    1986-01-01

    Luminescence proposed as nondestructive technique for measuring Shockley-Read-Hall (SRH) recombination lifetime GaAs. Sample irradiated, and luminescence escapes through surface. Measurement requires no mechanical or electrical contact with sample. No ohmic contacts or p/n junctions needed. Sample not scrapped after tested.

  6. Wide-range thermochromic luminescence of organoboronium complexes.

    PubMed

    Chen, Xiaofeng; Zhang, Xuepeng; Zhang, Guoqing

    2015-01-04

    Alkyl-substituted tetra-coordinate organoboronium bisdiketone complexes exhibit dramatic luminescence thermochromism in organic solvents. In glass-forming alcohols, these complexes exhibit a reversible aqua blue to orange-red to greenish yellow luminescence emission colour change upon cooling.

  7. Ultrashort pulse laser microsurgery system with plasma luminescence feedback control

    SciTech Connect

    Kim, B.M.; Feit, M.D.; Rubenchik, A.M.; Gold, D.M.; Darrow, C.B.; Da Silva, L.B.

    1997-11-10

    Plasma luminescence spectroscopy was used for precise ablation of bone tissue during ultrashort pulse laser (USPL) micro-spinal surgery. Strong contrast of the luminescence spectra between bone marrow and spinal cord provided the real time feedback control so that only bone tissue can be selectively ablated while preserving the spinal cord.

  8. Luminescent Processes Elucidated by Simple Experiments on ZnS.

    ERIC Educational Resources Information Center

    Schwankner, R.; And Others

    1981-01-01

    Describes some impurity-related optical properties of semiconductors, with special emphasis on the luminescence of zinc sulfide (ZnS). Presents and interprets five experiments using a ZnS screen, ultraviolet lamp, transparent Dewar liquid nitrogen, and a helium/neon gas base. Includes application of luminescence measurements to archaeology. (SK)

  9. Method for altering the luminescence of a semiconductor

    DOEpatents

    Barbour, J. Charles; Dimos, Duane B.

    1999-01-01

    A method is described for altering the luminescence of a light emitting semiconductor (LES) device. In particular, a method is described whereby a silicon LES device can be selectively irradiated with a radiation source effective for altering the intensity of luminescence of the irradiated region.

  10. Doped luminescent materials and particle discrimination using same

    DOEpatents

    Doty, F. Patrick; Allendorf, Mark D; Feng, Patrick L

    2014-10-07

    Doped luminescent materials are provided for converting excited triplet states to radiative hybrid states. The doped materials may be used to conduct pulse shape discrimination (PSD) using luminescence generated by harvested excited triplet states. The doped materials may also be used to detect particles using spectral shape discrimination (SSD).

  11. Method for altering the luminescence of a semiconductor

    DOEpatents

    Barbour, J.C.; Dimos, D.B.

    1999-01-12

    A method is described for altering the luminescence of a light emitting semiconductor (LES) device. In particular, a method is described whereby a silicon LES device can be selectively irradiated with a radiation source effective for altering the intensity of luminescence of the irradiated region. 4 figs.

  12. Experimental observation of the luminescence flash at the collapse phase of a bubble produced by pulsed discharge in water

    NASA Astrophysics Data System (ADS)

    Huang, Yifan; Zhang, Liancheng; Chen, Jim; Zhu, Xinlei; Liu, Zhen; Yan, Keping

    2015-11-01

    This letter presents an experimental observation of luminescence flash at the collapse phase of an oscillating bubble produced by a pulsed discharge in water. According to the high speed records, the flash lasts around tens of microseconds, which is much longer than the lifetime of laser and ultrasound induced luminescence flashes in nanoseconds and picoseconds, respectively. The pulse width of temperature waveform and minimum radius calculated at the collapse phase also show that the thermodynamic and dynamic signatures of the bubbles in this work are much larger than those of ultrasound and laser induced bubbles both in time and space scales. However, the peak temperature at the point of collapse is close to the results of ultrasound and laser induced bubbles. This result provides another possibility for accurate emission spectrum measurement other than amplification of the emitted light, such as increasing laser energy or sound energy or substituting water with sulphuric acid.

  13. Experimental observation of the luminescence flash at the collapse phase of a bubble produced by pulsed discharge in water

    SciTech Connect

    Huang, Yifan; Zhang, Liancheng; Zhu, Xinlei; Liu, Zhen Yan, Keping; Chen, Jim

    2015-11-02

    This letter presents an experimental observation of luminescence flash at the collapse phase of an oscillating bubble produced by a pulsed discharge in water. According to the high speed records, the flash lasts around tens of microseconds, which is much longer than the lifetime of laser and ultrasound induced luminescence flashes in nanoseconds and picoseconds, respectively. The pulse width of temperature waveform and minimum radius calculated at the collapse phase also show that the thermodynamic and dynamic signatures of the bubbles in this work are much larger than those of ultrasound and laser induced bubbles both in time and space scales. However, the peak temperature at the point of collapse is close to the results of ultrasound and laser induced bubbles. This result provides another possibility for accurate emission spectrum measurement other than amplification of the emitted light, such as increasing laser energy or sound energy or substituting water with sulphuric acid.

  14. Low-temperature luminescence and thermoluminescence from BeO:Zn single crystals

    NASA Astrophysics Data System (ADS)

    Ogorodnikov, I. N.; Petrenko, M. D.; Ivanov, V. Yu.

    2016-12-01

    Low-temperature luminescence and thermoluminescence (TL) of BeO:Zn single crystals have been studied in the temperature range of 6-380 K and energy ranges of 1.2-6.5 eV (emission spectra) and 3.7-20 eV (luminescence excitation and reflection spectra). The introduction of zinc impurity ions (0.05 at. %) into BeO host lattice leads to the creation of both the trapped electron and hole centers: Zn+ and Zn2+ O-. These two new centers are responsible for two TL glow peaks at 307 and 145 K with activation energies of 0.96 and 0.40 eV, and two emission bands at 6.0 and 1.9-2.6 eV. The first emission band is attributed to radiative annihilation of the Zn-impurity bound excitons, and the second one is associated with the intracenter electronic transitions in the defect complex comprising zinc impurity ion. The 6.0 eV luminescence center can be excited at 9.6 eV, the low-energy tail of the BeO host absorption, but below the first excitonic maximum (10.45 eV). The 1.9-2.6 eV luminescence center can be excited at the BeO optical transparency band. Both emission bands in BeO:Zn appear in the X-ray induced luminescence spectra at T = 6 K. This indicates that not only these luminescence centers are excited during band-to-band transitions, but they participate in recombination processes as well. The low-temperature (T0 = 6 K) TL study of BeO:Zn single crystals was made for the first time. Analysis of the low-temperature TL glow curves allowed us not only to experimentally determine the energy characteristics of the Zn impurity states in BeO:Zn, but reveal an extremely strong influence of the isovalent zinc impurity on fluctuation rearrangement of BeO host lattice. Note, the fluctuation rearrangement of BeO host lattice, which occurs in the temperature range of self-trapped exciton transformation (80-180 K), was previously known only for undoped BeO and BeO crystals with heterovalent impurities [I. N. Ogorodnikov and A. V. Kruzhalov, Proc. SPIE 2967 (1997) 42].

  15. Ullage Tank Fuel-Air Mixture Characterisation

    DTIC Science & Technology

    2011-12-01

    5 1.3 SOLID-PHASE MICROEXTRACTION ........................................................................ 7 1.4...National Institute of Standards and Testing PDMS Polydimethylsiloxane RPM Revolutions per minute SPME Solid-Phase Microextraction VOC...Mayfield, 1996). The technique chosen to characterise the vapour was headspace solid-phase microextraction (SPME), interfaced with a gas

  16. ATCA characterisation of first BETA fields

    NASA Astrophysics Data System (ADS)

    Feain, Ilana; Johnston, Simon

    2011-04-01

    To fully characterise 2 30 square degree fields that will become the first science fields observed on BETA and at the same time to extract new science from the ATCA observations. The fields are centred on the Circinus galaxy and the Fornax cluster (and including Fornax A)

  17. ZnO:Cu nanorods with visible luminescence: copper induced defect levels and its luminescence dynamics

    NASA Astrophysics Data System (ADS)

    Raji, R.; Gopchandran, K. G.

    2017-02-01

    In this work, we report the synthesis of ZnO:Cu nanoparticles with rod-like morphology using co-precipitation method. X-ray diffraction analysis indicated that these ZnO:Cu nanoparticles has wurtzite structure with preferential growth along (1 0 1) crystal plane. The formation of additional defect levels in these particles on doping with Cu was investigated using Raman and fluorescence spectroscopy. The increase in intensity of E 1 (LO) mode observed at ~580 cm‑1 in the Raman spectra of ZnO:Cu nanoparticles, confirmed the formation of additional defect levels in these nanoparticles on doping with Cu. The doping concentration was evident in the intensity of the additional Raman mode observed at ~280 cm‑1 for the Cu doped nanoparticles. Photoluminescence spectra of Cu doped ZnO nanoparticles shows three visible emission peaks at 413, 435 and 531 nm along with a UV emission peak at 390 nm, whereas undoped ZnO nanoparticles showed only two peaks, at 389 and 582 nm. The shrinkage in band gap causing the emission of violet, blue and green colors on doping with Cu are attributed to the s-d and p-d exchange interactions between conduction band electrons of ZnO and localized d electrons of Cu ions, resulting in renormalization of band gap. The emission bands observed in these ZnO:Cu nanoparticles has been illustrated with a schematic energy level diagram.

  18. Visible luminescence of dysprosium ions in oxyhalide lead borate glasses.

    PubMed

    Pisarska, Joanna; Żur, Lidia; Pisarski, Wojciech A

    2011-08-15

    Visible luminescence of Dy(3+) ions in oxyhalide lead borate glasses was examined. Luminescence spectra show two intense bands at 480 nm and 573 nm due to (4)F(9/2)→(6)H(15/2) (blue) and (4)F(9/2)→(6)H(13/2) (yellow) transitions of Dy(3+). Luminescence decays from (4)F(9/2) state and yellow-to-blue luminescence intensity ratios (Y/B) were analysed with PbX(2) (X=F, Cl) content. An introduction of PbX(2) to the borate glass results in the increasing of (4)F(9/2) lifetime and the decreasing of yellow-to-blue luminescence intensity ratio, which is due to reduction of covalency between Dy(3+) and O(2-)/X(-) ions.

  19. Photostimulated luminescence properties of Eu2+ -doped barium aluminate phosphor.

    PubMed

    He, Quanlong; Qiu, Guangyu; Xu, Xuhui; Qiu, Jianbei; Yu, Xue

    2015-03-01

    An intense green photostimulated luminescence in BaAl2 O4 :Eu(2+) phosphor was prepared. The thermoluminescence results indicate that there are at least three types of traps (T1 , T2 , T3 ) with different trap depths in BaAl2 O4 :Eu(2+) phosphor according to the bands located at 327, 361 and 555 K, respectively, which are closely associated with the phosphor's long persistent luminescence and photostimulated luminescence properties. In addition, as a novel optical read-out form, a photostimulated persistent luminescence signal can be repeatedly obtained in BaAl2 O4 :Eu(2+) phosphor. This shows that re-trapping of the electron released from a deep trap plays an important role in photostimulated persistent luminescence.

  20. Evanescent wave excited luminescence from levitated quantum dot modified colloids.

    PubMed

    Everett, W Neil; Beckham, Richard E; Meissner, Kenith; Bevan, Michael A

    2007-08-14

    Evanescent wave excited luminescence of quantum dot modified polystyrene (QDPS) colloids is investigated to measure potential energy profiles of QDPS colloids electrostatically levitated above a planar glass surface. Luminescence is characterized for three different-sized PS colloids modified with three different-sized QDs using confocal microscopy, emission spectra, flow cytometry, and temporal measurements of levitated and deposited colloids. Colloid-surface potential energy profiles constructed from scattering and luminescence intensity data display excellent agreement with each other, theoretical predictions, and independently measured parameters. QDPS luminescence intensity is indirectly confirmed to have an exponential dependence on height similar to conventional colloidal evanescent wave scattering. Our findings indicate that evanescent wave excited QDPS luminescence could enable total internal reflection microscopy measurements of index-matched hard spheres, multiple specific biomolecular interactions via spectral multiplexing, enhanced morphology-dependent resonance modes, and integrated evanescent wave-video-confocal microscopy experiments not possible with scattering.

  1. Luminescence and white-light emitting luminescent sensor of tetrafluoroterephthalate-lanthanide metal-organic frameworks.

    PubMed

    Han, Yongqiang; Yan, Pengfei; Sun, Jingwen; An, Guanghui; Yao, Xu; Li, Yuxin; Li, Guangming

    2017-03-22

    Two types of sixteen complexes 1-16, namely, {[Ln(TFBDC)1.5(H2O)]·2H2O}n [Ln = Pr (1) and Nd (2)] and {[Ln(TFBDC)1.5(H2O)2]·H2O}n [Ln = Ce (3), Pr (4), Nd (5), Sm (6), Eu (7), Gd (8), Tb (9), Dy (10), Ho (11), Er (12), Yb (13) and Lu (14)], {[Dy0.281Eu0.719(TFBDC)1.5(H2O)2]·H2O}n (15) and {[Gd0.871Eu0.103Tb0.026(TFBDC)1.5(H2O)2]·H2O}n (16), were isolated by the reaction of LnCl3·6H2O with 2,3,5,6-tetrafluoroterephthalic acid (H2TFBDC). X-ray crystallographic analysis revealed that 1 and 2 exhibit 3D network structures and complexes 3-14 feature 2D network structures formed via three different coordination modes of the ligand. Luminescence spectra revealed that these complexes exhibit broad-spectrum luminescence from the visible to the near-infrared (NIR) region. Unexpectedly, complex 1 exhibits a unique NIR luminescence pattern and the longest lifetime among reported molecular praseodymium complexes. White-light emission was realized via three approaches using the single-component complex 6 (Sm), the two-component complex 15 (Eu and Dy) and the three-component complex 16 (Eu, Tb and Gd). Complex 9 exhibits high sensitivity and selectivity in its luminescence response to benzaldehyde, which provides a promising luminescent sensor for the detection of benzaldehyde.

  2. Mitochondrial respiratory complex I probed by delayed luminescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Baran, Irina; Ionescu, Diana; Privitera, Simona; Scordino, Agata; Mocanu, Maria Magdalena; Musumeci, Francesco; Grasso, Rosaria; Gulino, Marisa; Iftime, Adrian; Tofolean, Ioana Teodora; Garaiman, Alexandru; Goicea, Alexandru; Irimia, Ruxandra; Dimancea, Alexandru; Ganea, Constanta

    2013-12-01

    The role of mitochondrial complex I in ultraweak photon-induced delayed photon emission [delayed luminescence (DL)] of human leukemia Jurkat T cells was probed by using complex I targeting agents like rotenone, menadione, and quercetin. Rotenone, a complex I-specific inhibitor, dose-dependently increased the mitochondrial level of reduced nicotinamide adenine dinucleotide (NADH), decreased clonogenic survival, and induced apoptosis. A strong correlation was found between the mitochondrial levels of NADH and oxidized flavin mononucleotide (FMNox) in rotenone-, menadione- and quercetin-treated cells. Rotenone enhanced DL dose-dependently, whereas quercetin and menadione inhibited DL as well as NADH or FMNox. Collectively, the data suggest that DL of Jurkat cells originates mainly from mitochondrial complex I, which functions predominantly as a dimer and less frequently as a tetramer. In individual monomers, both pairs of pyridine nucleotide (NADH/reduced nicotinamide adenine dinucleotide phosphate) sites and flavin (FMN-a/FMN-b) sites appear to bind cooperatively their specific ligands. Enhancement of delayed red-light emission by rotenone suggests that the mean time for one-electron reduction of ubiquinone or FMN-a by the terminal Fe/S center (N2) is 20 or 284 μs, respectively. All these findings suggest that DL spectroscopy could be used as a reliable, sensitive, and robust technique to probe electron flow within complex I in situ.

  3. Spectroscopic characteristic of conical bubble luminescence

    NASA Astrophysics Data System (ADS)

    Chen, Qi-Dai; Fu, Li-Min; Ai, Xi-Cheng; Zhang, Jian-Ping; Wang, Long

    2005-04-01

    The conical bubble sonoluminescence (CBSL) from the collapse of the bubble was observed in an improved U-tube apparatus. The emitted light energy of a single CBSL flash was measured to be ~ 1.4mJ. The pulse width was about 100μs. The spectra of luminescence were continuum superimposed with the spectral bands from the excited-state C2, CN and CH. The CBSL provides a link between the light emission of the single-bubble and the multi-bubble sonoluminescence (SBSL and MBSL).

  4. Thermally stimulated luminescence of urine salts

    NASA Astrophysics Data System (ADS)

    Bordun, O. M.; Drobchak, O. Z.

    2007-07-01

    We investigated thermally stimulated luminescence (TSL) of urine salts in the normal state and with oxalate, urate, and phosphate salts. We found that the presence of pathological salts leads to a decrease of TSL intensity and to the appearance of additional TLS bands with maxima at 118 and 205 K in addition to the characteristic bands at 173 and 260 K. The TLS bands are related to the urine components. The TSL intensities of urine salts of different chemical composition are compared. The thermal activation energy of the strongest TSL bands is determined.

  5. Image registration for luminescent paint applications

    NASA Technical Reports Server (NTRS)

    Bell, James H.; Mclachlan, Blair G.

    1993-01-01

    The use of pressure sensitive luminescent paints is a viable technique for the measurement of surface pressure on wind tunnel models. This technique requires data reduction of images obtained under known as well as test conditions and spatial transformation of the images. A general transform which registers images to subpixel accuracy is presented and the general characteristics of transforms for image registration and their derivation are discussed. Image resection and its applications are described. The mapping of pressure data to the three dimensional model surface for small wind tunnel models to a spatial accuracy of 0.5 percent of the model length is demonstrated.

  6. Circularly Polarized Luminescence from Simple Organic Molecules.

    PubMed

    Sánchez-Carnerero, Esther M; Agarrabeitia, Antonia R; Moreno, Florencio; Maroto, Beatriz L; Muller, Gilles; Ortiz, María J; de la Moya, Santiago

    2015-09-21

    This article aims to show the identity of "circularly polarized luminescent active simple organic molecules" as a new concept in organic chemistry due to the potential interest of these molecules, as availed by the exponentially growing number of research articles related to them. In particular, it describes and highlights the interest and difficulty in developing chiral simple (small and non-aggregated) organic molecules able to emit left- or right-circularly polarized light efficiently, the efforts realized up to now to reach this challenging objective, and the most significant milestones achieved to date. General guidelines for the preparation of these interesting molecules are also presented.

  7. High pressure luminescence probes in polymers

    SciTech Connect

    Drickamer, H.G.

    1980-01-01

    High pressure luminescence has proved to be a very powerful tool for characterizing crystalline solids and liquids. Two problems involving glassy polymers are analyzed. In the first problem the excited states of azulene and its derivatives are used to probe intermolecular interactions in PMMA and PS. In the second problem the change in emission intensity with pressure from two excimer states of polyvinylcarbazole as a pure polymer and in dilute solution in polystyrene (PS), polymethylmethacrylate (PMMA) and polyisoliutylene (PIB) is studied. The relative emission from the two states depends strongly on the possibility for motion of polymer segments. The observations are related to the proximity to the glass transition.

  8. Eu(2+) luminescence in strontium aluminates.

    PubMed

    Dutczak, D; Jüstel, T; Ronda, C; Meijerink, A

    2015-06-21

    The luminescence properties of Eu(2+) doped strontium aluminates are reported and reviewed for a variety of aluminates, viz. SrAl12O19, SrAl4O7, Sr4Al14O25, SrAl2O4 and Sr3Al2O6. The aim of the research is to investigate the role of local coordination and covalency of the aluminate host lattice, related to the Sr/Al ratio, on the optical properties of the Eu(2+) ion. The UV and VUV excited luminescence spectra as well as luminescence decay curves were recorded to characterize the luminescence properties of the investigated aluminates. The emission of Eu(2+) ions varies over a wide spectral range, from ultraviolet (UV) to red, for the series of aluminates. The variation in emission color can be related to the crystal-field splitting of the 5d levels and the covalent interaction with the surrounding oxygen anions. In the least covalent material, viz. SrAl12O19:Eu(2+), narrow line emission due to the (6)P7/2-(8)S7/2 transition occurs at 4 K, indicating that the 4f(6)5d excited state is situated above the (6)P7/2(4f(7)) excited state around 360 nm. The most alkaline material, viz. Sr3Al2O6:Eu(2+) is the most covalent host and exhibits several d-f emission bands in the yellow to red spectral range due to the Eu(2+) ions located on different crystallographic Sr(2+) sites. The Eu(2+) emission spectra in the other aluminates confirm the trend that with increasing Sr/Al ratio the Eu(2+) emission shifts to longer wavelengths. Interesting differences are observed for the Eu(2+) from different crystallographic sites which cannot always be related with apparent differences in the first oxygen coordination sphere. The discussion gives insight into how in a similar class of materials, strontium aluminates, the emission color of Eu(2+) can be tuned over a wide spectral region.

  9. Luminescence studies of individual quantum dot photocatalysts.

    PubMed

    Amirav, Lilac; Alivisatos, A Paul

    2013-09-04

    Using far-field optical microscopy we report the first measurements of photoluminescence from single nanoparticle photocatalysts. Fluence-dependent luminescence is investigated from metal-semiconductor heterojunction quantum dot catalysts exposed to a variety of environments, ranging from gaseous argon to liquid water containing a selection of hole scavengers. The catalysts each exhibit characteristic nonlinear fluence dependence. From these structurally and environmentally sensitive trends, we disentangle the separate rate-determining steps in each particle across the very wide range of time scales, which follow the initial light absorption process. This information will significantly benefit the design of effective artificial photocatalytic systems for renewable direct solar-to-fuel energy conversion.

  10. Polyethylene terephthalate thin films; a luminescence study

    NASA Astrophysics Data System (ADS)

    Carmona-Téllez, S.; Alarcón-Flores, G.; Meza-Rocha, A.; Zaleta-Alejandre, E.; Aguilar-Futis, M.; Murrieta S, H.; Falcony, C.

    2015-04-01

    Polyethylene Terephthalate (PET) films doped with Rare Earths (RE3+) have been deposited on glass by spray pyrolysis technique at 240 °C, using recycled PET and (RE3+) chlorides as precursors. Cerium, terbium, dysprosium and europium were used as dopants materials, these dopants normally produce luminescent emissions at 450, 545, 573 and 612 nm respectively; the doped films also have light emissions at blue, green, yellow and red respectively. All RE3+ characteristic emissions were observed at naked eyes. Every deposited films show a high transmission in the visible range (close 80% T), films surfaces are pretty soft and homogeneous. Films thickness is around 3 μm.

  11. Optical Receiver Based On Luminescent Light Trapping

    NASA Technical Reports Server (NTRS)

    Perry, Joseph W.; Cole, Terry; Zewail, Ahmed H.

    1991-01-01

    Experiment demonstrates feasibility of optical-communication receiver based on luminescent light trapping. Light-gathering element plate of transparent material impregnated with laser dye. Light from distant laser transmitter falls on plate and absorbed by dye molecules, which become excited and reradiate. Reradiated light confined within plate by total internal reflection as it propagates toward edge of plate. Light arriving at edge escapes from plate and detected by small, high-speed, high-gain photomultiplier tubes or other photosensitive devices. Simple, inexpensive, and accepts light from almost any angle. Receiver of this configuration supports reception of data at rate of 13 MHz and higher.

  12. Research Update: Luminescence in lead halide perovskites

    NASA Astrophysics Data System (ADS)

    Srimath Kandada, Ajay Ram; Petrozza, Annamaria

    2016-09-01

    Efficiency and dynamics of radiative recombination of carriers are crucial figures of merit for optoelectronic materials. Following the recent success of lead halide perovskites in efficient photovoltaic and light emitting technologies, here we review some of the noted literature on the luminescence of this emerging class of materials. After outlining the theoretical formalism that is currently used to explain the carrier recombination dynamics, we review a few significant works which use photoluminescence as a tool to understand and optimize the operation of perovskite based optoelectronic devices.

  13. Single layer multi-color luminescent display

    NASA Technical Reports Server (NTRS)

    Robertson, James B. (Inventor)

    1991-01-01

    The invention is a multi-color luminescent display comprising an insulator substrate and a single layer of host material which may be a phosphor deposited thereon that hosts one or more differential impurities, therein forming a pattern of selected and distinctly colored phosphors such as blue, green, and red phosphors in a single layer of host material. Transparent electrical conductor means may be provided for subjecting selected portions of the pattern of colored phosphors to an electric field thereby forming a multi-color, single layer electroluminescent display.

  14. Chemically engineered persistent luminescence nanoprobes for bioimaging

    PubMed Central

    Lécuyer, Thomas; Teston, Eliott; Ramirez-Garcia, Gonzalo; Maldiney, Thomas; Viana, Bruno; Seguin, Johanne; Mignet, Nathalie; Scherman, Daniel; Richard, Cyrille

    2016-01-01

    Imaging nanoprobes are a group of nanosized agents developed for providing improved contrast for bioimaging. Among various imaging probes, optical sensors capable of following biological events or progresses at the cellular and molecular levels are actually actively developed for early detection, accurate diagnosis, and monitoring of the treatment of diseases. The optical activities of nanoprobes can be tuned on demand by chemists by engineering their composition, size and surface nature. This review will focus on researches devoted to the conception of nanoprobes with particular optical properties, called persistent luminescence, and their use as new powerful bioimaging agents in preclinical assays. PMID:27877248

  15. Development of novel edible luminescent nanoparticle sensors

    NASA Astrophysics Data System (ADS)

    Jalalian, Sanaz

    This project has developed a novel class of edible hydrocolloid food nanosensors which are doped with luminescent chromophores and investigated whether they can be used to provide information about the local food matrix - temperature, oxygen concentration, and the presence of food-borne pathogens. The luminescence properties of the probes such as phosphorescence and fluorescence provide the sensor sensitivity to the food properties. Hydrocolloid nanoparticles were made from gelatin and starch with diameters ranging from 50 to ˜200 nm and labeled with food grade luminescent probes. The chromophore was covalently and non-covalently attached to the nanoparticle and the photophysical properties of the probe in the food system were studied. Temperature sensors were developed by using the phosphorescence sensitivity of a chromophore to temperature. Experiments with two different probes, namely erythrosine B labeled gelatin nanoparticles and phloxine B labeled gelatin nanoparticles have demonstrated that both probes can be effectively used as temperature sensors in liquid and solid food. The Van't Hoff plots of ln(IDF/IP) versus 1/T vary monotonically over a relatively wide temperature range and thus provide a basis for estimating temperature from measurements of phosphorescence and delayed fluorescence. The tests indicated that the presence of some ingredients such as tannin and anthocyanins in the composition of the food may prohibit the use of gelatin nanoparticle probes due to precipitation of gelatin nanoparticles. The luminescence quenching of the probe by oxygen was used to develop a nanoparticle sensor for oxygen. The results of experiments on liquid and solid food samples indicate that erythrosine B labeled gelatin nanoparticles can be used as a probe to detect the presence or absence of oxygen in some liquid foods. Precise control of oxygen concentration in solutions will pose a challenge as has been observed in this study. The probe did not work as an

  16. Use of luminescent Leptospira interrogans for enumeration in biological assays.

    PubMed

    Murray, Gerald L; King, Amy M; Srikram, Amporn; Sermswan, Rasana W; Adler, Ben

    2010-06-01

    Rapid and reliable in vitro methods for the detection of pathogenic leptospires, such as Leptospira interrogans, are lacking. The present study investigated the use of luminescence to replace the existing enumeration techniques. Transposon TnSC189 was modified to incorporate the luxCDABE cassette from Photorhabdus luminescens and was used to construct luminescent Leptospira spp. There was a linear relationship between luminescence and cell number, with the theoretical detection limit being less than 10(4) leptospires. A comparison of enumeration by a standard method (counting by dark-field microscopy) and enumeration by luminescence was conducted with luminescent L. interrogans. There was a good correlation between the two methods of enumeration (R(2) = 0.766), although variation in the luminescence early and late in growth phase reduced the degree of correlation. To demonstrate the utility of luminescence as a viability and cell number reporter, in vitro assays, including MIC determination, an extracellular matrix binding experiment, and a complement killing experiment, were conducted. In each case, the results obtained by luminescence matched those obtained by traditional means with high correlations (binding assay R(2) = 0.916, complement killing assay R(2) = 0.988). A strain expressing the luxCDABE transposon retained virulence in the hamster model of infection. Despite some variation in luminescence as a result of the growth phase or the particular assay conditions, enumeration by luminescence was found to be a quick, reliable, and highly sensitive method for the in vitro detection of leptospires that has the potential to replace more time-consuming methods of enumeration.

  17. Photoluminescence and photostimulated luminescence of oxygen impurities in CsBr

    SciTech Connect

    Appleby, G. A.; Zimmermann, J.; Hesse, S.; Seggern, H. von

    2011-01-01

    Oxygen impurities have been detected in undoped CsBr by photoluminescence (PL) spectroscopy and their contribution to photostimulated luminescence (PSL) properties of powdered CsBr is discussed. When excited at 200 nm, PL is observed from CsBr which consists of three separate emission peaks. The intrinsic luminescence of CsBr at 379 nm is accompanied by two emission peaks at 395 and 460 nm which arise from oxygen impurities, the latter of which is also PSL active following x-irradiation. Sintering of CsBr with the reducing agent NH{sub 4}Br removes the oxygen impurities so that the 395 and 460 nm emissions are no longer detectable, and subsequently the PSL emission is significantly reduced. PSL storage time measurements of these materials show that oxygen impurities favorably increase both the PSL sensitivity and radiation induced charge-center stability in CsBr:Eu{sup 2+}. The oxygen impurities and their associated luminescence properties can be reintroduced to the CsBr matrix with a controlled concentration by doping with CsOH and then subsequently sintering the resultant CsBr:OH{sup -} with NH{sub 4}Br, which in this system reduces the OH{sup -} centers to O{sup 2-}.

  18. Order and disorder around Cr(3+) in chromium doped persistent luminescent AB2O4 spinels.

    PubMed

    Basavaraju, Neelima; Priolkar, Kaustubh R; Gourier, Didier; Bessière, Aurélie; Viana, Bruno

    2015-04-28

    The X-ray absorption near edge structure (XANES) spectroscopy technique is used to better understand the charging and decharging processes of the persistent luminescence in the Cr(3+)doped AB2O4 spinels (A = Zn, Mg and B = Ga and Al) with low photon energy excitation by visible light. Cr K edge XANES spectra have been simulated for different near neighbour environments around the Cr(3+) recombination centres and compared with the experimental curve. In the Cr(3+):ZnGa2O4 compound, the Cr(3+) local structure corresponds mostly to that of a normal spinel (∼70%), while the rest comprises of a distorted octahedral environment arising from cationic site inversion and a contribution from chromium clustering. This local structure is considerably different in Cr(3+):MgGa2O4 and Cr(3+):ZnAl2O4, where, for both cases, chromium clustering represents the main contribution. The strong correlation between the intensity of persistent luminescence and the percentage of Cr in clusters leads us to infer that the presence of Cr clusters is responsible for the decrease of the intensity of the visible light induced persistent luminescence in the Cr(3+) doped AB2O4 spinels.

  19. Directional Surface Plasmon Coupled Luminescence for Analytical Sensing Applications: Which Metal, What Wavelength, What Observation Angle?

    PubMed Central

    Aslan, Kadir; Geddes, Chris D.

    2009-01-01

    The ability of luminescent species in the near-field to both induce and couple to surface plasmons has been known for many years, with highly directional emission from films (Surface Plasmon Coupled Luminescence, SPCL) facilitating the development of sensitive near-field assay sensing platforms, to name but just one application. Because of the near-field nature of the effect, only luminescent species (fluorescence, chemiluminescence and phosphorescence) within a few hundred nanometers from the surface play a role in coupling, which in terms of biosensing, provides for limited penetration into optically dense media, such as in whole blood. Another attractive feature is the highly polarized and angular dependent emission which allows both fixed angle and wavelength dependent emission angles to be realized at high polarization ratios. In this paper, a generic procedure based on theoretical Fresnel calculations, which outlines the step-by-step selection of an appropriate metal for SPCL applications is presented. It is also shown that 11 different metals have differing properties in different spectral regions and offer either fixed angle or wavelength-dependent angular shifts in emission. In addition, it is shown that both chemiluminescence and phosphorescence can also be observed in a highly directional manner similar to coupled fluorescence. PMID:19601619

  20. In-situ luminescence monitoring of ion-induced damage evolution in SiO2 and Al2O3

    SciTech Connect

    Crespillo, Miguel L.; Graham, Joseph T.; Zhang, Yanwen; Weber, William J.

    2015-12-17

    Real-time, in-situ ionoluminescence measurements provide information of evolution of emission bands with ion fluence, and thereby establish a correlation between point defect kinetics and phase stability. Using fast light ions (2 MeV H and 3.5 He MeV) and medium mass-high energy ions (8 MeV O, E=0.5 MeV/amu), scintillation materials of a-SiO2, crystalline quartz, and Al2O3 are comparatively investigated at room temperature with the aim of obtaining a further insight on the structural defects induced by ion irradiation and understand the role of electronic energy loss on the damage processes. For more energetic heavy ions, the electronic energy deposition pattern offers higher rates of excitation deeper into the material and allows to evaluate the competing mechanisms between the radiative and non-radiative de-excitation processes. Irradiations with 8 MeV O ions have been selected corresponding to the electronic stopping regime, where the electronic stopping power is dominant, and above the critical amorphization threshold for quartz. Lastly, the usefulness of IBIL and its specific capabilities as a sensitive tool to investigate the material characterization and evaluation of radiation effects are demonstrated.

  1. Influence of lanthanide ion energy levels on luminescence of corresponding metalloporphyrins.

    PubMed

    Zhao, Huimin; Zang, Lixin; Guo, Chengshan

    2017-03-15

    Lanthanide (Ln) porphyrins exhibit diverse luminescence properties that have not been fully explained yet. A series of Ln ions (Ln ions = La(3+), Ce(3+), Pr(3+), Nd(3+), Sm(3+), Eu(3+), Gd(3+), Tb(3+), Dy(3+), Ho(3+), Er(3+), Tm(3+), Yb(3+), and Lu(3+)) were coordinated with hematoporphyrin monomethyl ether (HMME), and their luminescence properties and related differences were studied. Spectral analysis indicated that all Ln-HMMEs exhibit fluorescence emission. Gd- and Lu-HMMEs were the only lanthanide-HMMEs displaying strong molecular π-π room-temperature phosphorescence (RTP) with quantum yield ΦP > 10(-3). Tb(3+) can also induce RTP from HMME but ΦP of Tb-HMME is much smaller (ΦP ∼ 10(-4)). The observed luminescence property differences were analyzed in detail, focusing on the 4f energy levels of Ln ions. These levels mostly lie below the lowest singlet (S1) and triplet (T1) excited states of HMME, resulting in energy transfer from the T1 state in HMME to Ln ions and, therefore, in the absence of RTP from the corresponding metalloporphyrins. Gd(3+) and Lu(3+) are the only lanthanide ions not possessing such 4f energy levels, avoiding T1 quenching in Gd- and Lu-HMMEs. Although Tb(3+) has low-lying 4f energy levels, the corresponding transition from the ground state is partly forbidden, resulting in weak energy transfer from HMME to Tb(3+) that accounts for the low RTP quantum yield of the corresponding complex. Thus, our results indicate that the luminescence property differences of lanthanide porphyrins are due to the disparate energy levels of the Ln ions.

  2. Reverse lyotropic liquid crystals from europium nitrate and P123 with enhanced luminescence efficiency.

    PubMed

    Yi, Sijing; Li, Qintang; Liu, Hongguo; Chen, Xiao

    2014-10-02

    Fabrication of lyotropic aggregates containing the lanthanide ions is becoming a preferable way to prepare novel functional materials. Here, the lyotropic liquid crystals (LLCs) of reverse hexagonal, reverse bicontinuous cubic, and lamellar phases have been constructed in sequence directly from the mixtures of Eu(NO3)3·6H2O and Pluronic P123 amphiphilc block copolymer with increasing the salt proportion. Their phase types and structural characteristics were analyzed using polarized optical microscopy (POM) and small-angle X-ray scattering (SAXS) measurements. The driving forces of reverse LLC phase formation were investigated using Fourier-transformed infrared spectroscopy (FTIR) and rheological measurements. The hydrated europium salt was found to act not only as a solvent here, but also as the bridge to form hydrogen bonding between coordinated water molecules and PEO blocks, which played a key role in the reverse LLCs formation. Compared to those in aqueous solutions and solid state, the enhanced luminescence quantum yields and prolonged excited state lifetimes were observed in two europium containing reverse mesophases. The luminescence quenching effect of lanthanide ions was efficiently suppressed, probably due to the substitution of coordinated water molecules by oxyethyl groups of P123 and ordered phase structures of LLCs, where the coordinated europium ions were confined and isolated by PEO blocks. The optimum luminescence performance was then found to exist in the reverse hexagonal phase. The obtained results on such lanthanide-induced reverse LLCs should be referable for designing new luminescent soft materials construction to expand their application fields.

  3. X-ray luminescence based spectrometer for investigation of scintillation properties

    SciTech Connect

    Varney, C. R.; Khamehchi, M. A.; Ji, Jianfeng; Selim, F. A.

    2012-10-15

    A new x-ray luminescence based spectrometer was developed and installed to examine the scintillation properties of materials while revealing the origins of luminescence and investigating trapping defects. Measurements were performed on a number of undoped and Ce doped yttrium aluminum garnet crystals and various luminescence centers were characterized. The measured x-ray luminescence spectra provide information about the spectral range and the scintillation efficiency and linearity. The efficiency of charge-carriers production due to x ray, their energy transfer to the luminescence centers, and the efficiency of luminescence are all reflected in the efficiency of x-ray luminescence.

  4. Novel luminescent nanoparticles for DNA detection

    NASA Astrophysics Data System (ADS)

    Dong, Ling; Yang, Zhihua; Zhang, Yi; Zhu, Yanyu; Wang, Lun; Wang, Leyu

    2010-05-01

    Highly luminescent LaF 3:Ce 3+/Tb 3+ nanocrystals were successfully prepared and surface functionalized via Layer-by-Layer technology. These as-prepared nanocrystals are highly resistant to photobleaching and pretty dispersible in aqueous solution. Due to the efficient luminescence quenching of the nanocrystals by nucleic acids, a facile fluorescence quenching method was developed for the detection of trace amount of nucleic acids. Under optimal conditions, the fluorescence intensity was proportional to the DNA concentration over the range of 0.60-25.0 μg mL -1 for calf thymus DNA (ct-DNA) and 0.60-30.0 μg mL -1 for herring sperm DNA (hs-DNA), respectively. The corresponding detection limit is 0.21 μg mL -1 for ct-DNA and 0.31 μg mL -1 for hs-DNA, respectively. The results indicated that the reported method is simple and rapid with wide linear range. Also, the recovery and relative standard deviation of this method are reasonable and satisfactory.

  5. Luminescent ruthenium complexes for theranostic applications.

    PubMed

    Cardoso, Carolina R; Lima, Márcia V S; Cheleski, Juliana; Peterson, Erica J; Venâncio, Tiago; Farrell, Nicholas P; Carlos, Rose M

    2014-06-12

    The water-soluble and visible luminescent complexes cis-[Ru(L-L)2(L)2](2+) where L-L = 2,2-bipyridine and 1,10-phenanthroline and L= imidazole, 1-methylimidazole, and histamine have been synthesized and characterized by spectroscopic techniques. Spectroscopic (circular dichroism, saturation transfer difference NMR, and diffusion ordered spectroscopy NMR) and isothermal titration calorimetry studies indicate binding of cis-[Ru(phen)2(ImH)2](2+) and human serum albumin occurs via noncovalent interactions with K(b) = 9.8 × 10(4) mol(-1) L, ΔH = -11.5 ± 0.1 kcal mol(-1), and TΔS = -4.46 ± 0.3 kcal mol(-1). High uptake of the complex into HCT116 cells was detected by luminescent confocal microscopy. Cytotoxicity of cis-[Ru(phen)2(ImH)2](2+) against proliferation of HCT116p53(+/+) and HCT116p53(-/-) shows IC50 values of 0.1 and 0.7 μmol L(-1). Flow cytometry and western blot indicate RuphenImH mediates cell cycle arrest in the G1 phase in both cells and is more prominent in p53(+/+). The complex activates proapoptotic PARP in p53(-/-), but not in p53(+/+). A cytostatic mechanism based on quantification of the number of cells during the time period of incubation is suggested.

  6. Analysis of excitation mechanisms of Ho3+ upconversion luminescence in Ho3+:LiYbF4 (0.2 at %) crystal via photographs of its longitudinal cross sections and via spectral and kinetic characteristics

    NASA Astrophysics Data System (ADS)

    Kazakov, B. N.; Mikheev, A. V.; Goriev, O. G.; Korableva, S. L.; Semashko, V. V.

    2016-10-01

    The results of a complex analysis of the excitation mechanisms of the up conversion luminescence of Ho3+:LiYbF4 (0.2 at %) crystal are presented. The spatial distribution of the upconversion luminescence intensity is studied by the photographs of longitudinal cross sections at different positions of the laser beam waist with respect to the sample. The surface power density of the pump laser diode radiation (0.755 W, λ = 933 nm) was changed by focusing the beam (similar to Z-scanning). The dependences of the longitudinal luminescence cross sections, as well as of the spectral and kinetic characteristics of Ho3+ and Yb3+ luminescence, on the position of the laser beam waist are determined. It is found that there exist two different mechanisms of the population of the energy levels of Ho3+ ions from which green and red luminescence occur, namely, cooperative sensitization of luminescence and absorption of induced photon groups (JETP Letters, 102 (5), 279 (2015)). It is shown that the contributions of these mechanisms vary both in time and over the crystal volume. All the observed spatial, spectral, and temporal specific features of the upconversion luminescence of Ho3+:LiYbF4 (0.2 at %) crystal are qualitatively explained.

  7. Luminescent chiral lanthanide(III) complexes as potential molecular probes

    PubMed Central

    Muller, Gilles

    2009-01-01

    This perspective gives an introduction into the design of luminescent lanthanide(III)-containing complexes possessing chiral properties and used to probe biological materials. The first part briefly describes general principles, focusing on the optical aspect (i.e. lanthanide luminescence, sensitization processes) of the most emissive trivalent lanthanide ions, europium and terbium, incorporated into molecular luminescent edifices. This is followed by a short discussion on the importance of chirality in the biological and pharmaceutical fields. The second part is devoted to the assessment of the chiroptical spectroscopic tools available (typically circular dichroism and circularly polarized luminescence) and the strategies used to introduce a chiral feature into luminescent lanthanide(III) complexes (chiral structure resulting from a chiral arrangement of the ligand molecules surrounding the luminescent center or presence of chiral centers in the ligand molecules). Finally, the last part illustrates these fundamental principles with recent selected examples of such chiral luminescent lanthanide-based compounds used as potential probes of biomolecular substrates. PMID:19885510

  8. Persistent luminescence properties of SrMg2(PO4)2:Eu2+,Tb3+

    NASA Astrophysics Data System (ADS)

    Ju, Guifang; Hu, Yihua; Chen, Li; Wang, Xiaojuan; Hung, Lihua

    2014-03-01

    We investigate the persistent luminescence in europium-doped SrMg2(PO4)2 upon codoping with auxiliary terbium. Luminescence properties of the phosphors, including photoluminescence, luminescence decay and thermoluminescence, are systematically studied. SrMg2(PO4)2:Eu2+ shows only a weak persistent luminescence, and codoping with Tb3+ is necessary to obtain considerable persistent luminescence. An energy level scheme is constructed to convey reasonable trapping and detrapping processes in the material.

  9. Genomic location and characterisation of MIC genes in cattle.

    PubMed

    Birch, James; De Juan Sanjuan, Cristina; Guzman, Efrain; Ellis, Shirley A

    2008-08-01

    Major histocompatibility complex (MHC) class I chain-related (MIC) genes have been previously identified and characterised in human. They encode polymorphic class I-like molecules that are stress-inducible, and constitute one of the ligands of the activating natural killer cell receptor NKG2D. We have identified three MIC genes within the cattle genome, located close to three non-classical MHC class I genes. The genomic position relative to other genes is very similar to the arrangement reported in the pig MHC region. Analysis of MIC cDNA sequences derived from a range of cattle cell lines suggest there may be four MIC genes in total. We have investigated the presence of the genes in distinct and well-defined MHC haplotypes, and show that one gene is consistently present, while configuration of the other three genes appears variable.

  10. A predictive typology for characterising hydromorphology

    NASA Astrophysics Data System (ADS)

    Orr, H. G.; Large, A. R. G.; Newson, M. D.; Walsh, C. L.

    2008-08-01

    Whilst traditionally poorly quantified, the link between physical habitat and ecological response in rivers is widely recognised, and is currently rising up legislative and policy agendas. In Europe, this is reflected in the Water Framework Directive which dictates that 'hydromorphological' condition of water bodies should be capable of supporting 'Good Ecological Status'. Methods are developed that integrate river system hydrology, geomorphology and ecology (and the complex interplay between these three variables). Whilst hydrological and biological methods for characterisation are relatively well established, geomorphological methods are not. Effective characterisation of geomorphology (physical habitat) with full spatial coverage, at a range of scales, can be used to explore spatial interactions between habitat and biological data and potentially further our understanding of ecological response. Managers need to know what aspects of physical habitat and at which critical locations intervention will lead to greatest improvements in ecological condition. This requires information on hydromorphological character and condition. Existing applied approaches for capturing geomorphological data are highly dependent on intensive fieldwork, which is unlikely to be resourced at sufficiently extensive scales to meet management needs. This paper outlines a typology approach for characterising the physical template of rivers. It draws on a range of hydromorphological data to develop a framework for a channel typology; with data collation from secondary sources followed by targeted fieldwork to (i) assess to what extent individual channel types are characteristic of field conditions and (ii) to collect information on reach-scale variability within each type. Results suggest that characterisation of channel types based on stream power, floodplain width and stream order does result in a distinct set of channel types. Field survey subsequently found that these types had a

  11. Microstructural characterisation of nuclear grade graphite

    NASA Astrophysics Data System (ADS)

    Jones, A. N.; Hall, G. N.; Joyce, M.; Hodgkins, A.; Wen, K.; Marrow, T. J.; Marsden, B. J.

    2008-10-01

    Field emission and transmission electron microscopy are used to characterise the microstructure and morphology of baked carbon block and graphitized grades (from the same carbon block stock) of nuclear graphite. Quantitative analysis using Raman and energy dispersive spectroscopy (EDS) were used to investigate the decrease of crystallinity with graphitization and sample purity. Both baked carbon and graphitized nuclear graphites show no sensitivity of the Raman band shift to strain, consistent with strain accommodation by the porous structure.

  12. Characterisation of rollator use using inertial sensors.

    PubMed

    Cheng, Tsu-Jui; Kenney, Laurence; Amor, James David; Thies, Sibylle Brunhilde; Costamagna, Eleonora; James, Christopher; Holloway, Catherine

    2016-12-01

    The use of walking aids is prevalent among older people and people with mobility impairment. Rollators are designed to support outdoor mobility and require the user to negotiate curbs and slopes in the urban environment. Despite the prevalence of rollators, analysis of their use outside of controlled environments has received relatively little attention. This Letter reports on an initial study to characterise rollator movement. An inertial measurement unit (IMU) was used to measure the motion of the rollator and analytical approaches were developed to extract features characterising the rollator movement, properties of the surface and push events. The analytics were tested in two situations: first, a healthy participant used a rollator in a laboratory using a motion capture system to obtain ground truth. Second, the IMU was used to measure the movement of a rollator being used by a user with multiple sclerosis on a flat surface, cross-slope, up and down slopes and up and down a step. The results showed that surface inclination and distance travelled measured by the IMU have close approximation to the results from ground truth; therefore, demonstrating the potential for IMU-derived metrics to characterise rollator movement and user's pushing style in the outdoor environment.

  13. The characterisation of commercial lubricant formulations

    SciTech Connect

    Scrivens, J.; Yates, H.; Bunn, A.

    1995-12-31

    Modern lubricant formulations are complex mixtures of base esters, antiwear additives, corrosion inhibitors and other modifiers. Their characterisation poses a difficult analytical challenge. A major market for these products is in the replacement of traditional CFC based refrigerants by modern alternatives. Conventional lubricants such as mineral oil are incompatible with the new refrigerants. Soft ionisation mass spectrometry (CI, LSIMS and FID), coupled with tandem mass spectrometry where required, has been used in conjunction with GC-MS and NMR in order to characterise these formulations. Statistical analysis of the soft ionisation data has provided further information regarding the detailed composition of the complex esters. This combination of experimental approaches provides a powerful method for the characterisation of these materials. A number of different types of polyol are used in the manufacture of the base esters with tetra- and hexa-esters the most common. The acids used, in general, vary in carbon number and in isomeric distribution and this leads to considerable complexity in the product.

  14. Characterisation of rollator use using inertial sensors

    PubMed Central

    Kenney, Laurence; Amor, James David; Thies, Sibylle Brunhilde; Costamagna, Eleonora; James, Christopher; Holloway, Catherine

    2016-01-01

    The use of walking aids is prevalent among older people and people with mobility impairment. Rollators are designed to support outdoor mobility and require the user to negotiate curbs and slopes in the urban environment. Despite the prevalence of rollators, analysis of their use outside of controlled environments has received relatively little attention. This Letter reports on an initial study to characterise rollator movement. An inertial measurement unit (IMU) was used to measure the motion of the rollator and analytical approaches were developed to extract features characterising the rollator movement, properties of the surface and push events. The analytics were tested in two situations: first, a healthy participant used a rollator in a laboratory using a motion capture system to obtain ground truth. Second, the IMU was used to measure the movement of a rollator being used by a user with multiple sclerosis on a flat surface, cross-slope, up and down slopes and up and down a step. The results showed that surface inclination and distance travelled measured by the IMU have close approximation to the results from ground truth; therefore, demonstrating the potential for IMU-derived metrics to characterise rollator movement and user's pushing style in the outdoor environment. PMID:28008367

  15. Interference effects in luminescence studies of thin films.

    PubMed

    Holm, R T; McKnight, S W; Palik, E D; Lukosz, W

    1982-07-15

    Interference effects, including multiple-beam and wide-angle, associated with luminescence from within a thin film are described. A simple geometrical model is used to calculate the s- and p-polarized luminescent light assuming electric-dipole radiation. The luminescence exhibits fringes when measured both as a function of the film thickness and as a function of the wavelength of the light. In the latter case the fringes can also show a beating effect. The model is applied to several experimental examples of cathodoluminescence in SiO(2) and an example of photoluminescence in a-Si.

  16. Luminescence dating of the Wabar meteorite craters, Saudi Arabia

    USGS Publications Warehouse

    Prescott, J.R.; Robertson, G.B.; Shoemaker, C.; Shoemaker, E.M.; Wynn, J.

    2004-01-01

    Luminescence dating has been used to find the age of meteorite impact craters at Wabar (Al Hadida) in Saudi Arabia. The luminescence characteristics of the shocked material were determined. Using a variety of luminescence dating techniques applied to impactite formed by the meteorite, and to the underlying sand, the age is found to be 290 ± 38 years. A comparison is made with two possible historically recorded ages. An impact as young as this has implications for the assessment of hazards from the impact on Earth of small meteorites.

  17. Surface pressure measurement by oxygen quenching of luminescence

    NASA Technical Reports Server (NTRS)

    Gouterman, Martin P. (Inventor); Kavandi, Janet L. (Inventor); Gallery, Jean (Inventor); Callis, James B. (Inventor)

    1994-01-01

    Methods and compositions for measuring the pressure of an oxygen-containing gas on an aerodynamic surface, by oxygen-quenching of luminescence of molecular sensors is disclosed. Objects are coated with luminescent films containing a first sensor and at least one of two additional sensors, each of the sensors having luminescences that have different dependencies on temperature and oxygen pressure. Methods and compositions are also provided for improving pressure measurements (qualitative or quantitive) on surfaces coated with a film having one or more types of sensor.

  18. Surface pressure measurement by oxygen quenching of luminescence

    NASA Technical Reports Server (NTRS)

    Gouterman, Martin P. (Inventor); Kavandi, Janet L. (Inventor); Gallery, Jean (Inventor); Callis, James B. (Inventor)

    1993-01-01

    Methods and compositions for measuring the pressure of an oxygen-containing gas on an aerodynamic surface, by oxygen-quenching of luminescence of molecular sensors is disclosed. Objects are coated with luminescent films containing a first sensor and at least one of two additional sensors, each of the sensors having luminescences that have different dependencies on temperature and oxygen pressure. Methods and compositions are also provided for improving pressure measurements (qualitative or quantitive) on surfaces coated with a film having one or more types of sensor.

  19. Luminescence, electron paramagnetic resonance, and optical properties of lunar material.

    PubMed

    Geake, J E; Dollfus, A; Garlick, G F; Lamb, W; Walker, C; Steigmann, G A; Titulaer, C

    1970-01-30

    Dust samples have been found to luminesce weakly under proton excitation, but not under ultraviolet. Damage, recovery, and heating effects have been investigated. Chips of breccia show luminescence, from white inclusions only, under ultraviolet and protons. Some rock chips show general luminescence, mainly from plagioclase. No natural or excited thermoluminescence has been found for dust or chips. The electron paramagnetic resonance spectrum shows the same broad Fe(3+) dipole resonance for dust and for some chips; other chips show no response. The polarization characteristics of dust are found to be identical to those of the Sea of Tranquillity, independently of proton damage. Chips show characteristics unlike any part of the lunar surface.

  20. Ligand sensitized luminescence of uranyl by benzoic acid in acetonitrile medium: a new luminescent uranyl benzoate specie.

    PubMed

    Kumar, Satendra; Maji, S; Joseph, M; Sankaran, K

    2015-03-05

    Benzoic acid (BA) is shown to sensitize and enhance the luminescence of uranyl ion in acetonitrile medium. Luminescence spectra and especially UV-Vis spectroscopy studies reveal the formation of tri benzoate complex of uranyl i.e. [UO2(C6H5COO)3](-) which is highly luminescent. In particular, three sharp bands at 431, 443, 461nm of absorption spectra provides evidence for tri benzoate specie of uranyl in acetonitrile medium. The luminescence lifetime of uranyl in this complex is 68μs which is much more compared to the lifetime of uncomplexed uranyl (20μs) in acetonitrile medium. In contrary to aqueous medium where uranyl benzoate forms 1:1 and 1:2 species, spectroscopic data reveal formation of 1:3 complex in acetonitrile medium. Addition of water to acetonitrile results in decrease of luminescence intensity of this specie and the luminescence features implode at 20% (v/v) of water content. For the first time, to the best of our knowledge, the existence of [UO2(C6H5COO)3](-) specie in acetonitrile is reported. Mechanism of luminescence enhancement is discussed.

  1. A Leaf-Inspired Luminescent Solar Concentrator for Energy-Efficient Continuous-Flow Photochemistry.

    PubMed

    Cambié, Dario; Zhao, Fang; Hessel, Volker; Debije, Michael G; Noël, Timothy

    2017-01-19

    The use of solar light to promote chemical reactions holds significant potential with regard to sustainable energy solutions. While the number of visible light-induced transformations has increased significantly, the use of abundant solar light has been extremely limited. We report a leaf-inspired photomicroreactor that constitutes a merger between luminescent solar concentrators (LSCs) and flow photochemistry to enable green and efficient reactions powered by solar irradiation. This device based on fluorescent dye-doped polydimethylsiloxane collects sunlight, focuses the energy to a narrow wavelength region, and then transports that energy to embedded microchannels where the flowing reactants are converted.

  2. Optical absorption and luminescence studies of fast neutron-irradiated complex oxides for jewellery applications

    NASA Astrophysics Data System (ADS)

    Mironova-Ulmane, N.; Skvortsova, V.; Popov, A. I.

    2016-07-01

    We studied the optical absorption and luminescence of agate (SiO2), topaz (Al2[SiO4](F,OH)2), beryl (Be3Al2Si6O18), and prehnite (Ca2Al(AlSi3O10)(OH)2) doped with different concentrations of transition metal ions and exposed to fast neutron irradiation. The exchange interaction between the impurity ions and the defects arising under neutron irradiation causes additional absorption as well as bands' broadening in the crystals. These experimental results allow us to suggest the method for obtaining new radiation-defect induced jewellery colors of minerals due to neutron irradiation.

  3. Ti:Sapphire micro-structures by femtosecond laser inscription: Guiding and luminescence properties

    NASA Astrophysics Data System (ADS)

    Ren, Yingying; Jiao, Yang; Vázquez de Aldana, Javier R.; Chen, Feng

    2016-08-01

    We report on the fabrication of buried cladding waveguides with different diameters in a Ti:Sapphire crystal by femtosecond laser inscription. The propagation properties are studied, showing that the cladding waveguides could support near- to mid-infrared waveguiding at both TE and TM polarizations. Confocal micro-photoluminescence experiments reveal that the original fluorescence properties in the waveguide region are very well preserved, while it suffers from a strong quenching at the centers of laser induced filaments. Broadband waveguide fluorescence emissions with high efficiency are realized, indicating the application of the cladding waveguides in Ti:Sapphire as compact broadband luminescence sources in biomedical fields.

  4. Magnetic and luminescent properties of vanadium-doped ZnSe crystals

    NASA Astrophysics Data System (ADS)

    Radevici, Ivan; Nedeoglo, Natalia; Sushkevich, Konstantin; Huhtinen, Hannu; Nedeoglo, Dmitrii; Paturi, Petriina

    2016-12-01

    Magnetic and photoluminescence properties of vanadium-doped ZnSe crystals with impurity concentrations varied by changing the V amount in the source material from 0.03 to 0.30 at% are studied in 5-300 K temperature range. Investigation of magnetic properties shows that the studied concentrations of vanadium impurity that should not disturb crystal lattice are insignificant for observing ferromagnetic behaviour even at low temperatures. The contribution of V impurity to edge emission and its influence on infra-red emission are discussed. Similarities of magnetic and luminescent properties induced by vanadium and other transition metal impurities are discussed.

  5. Excitonic luminescence upconversion in a two-dimensional semiconductor

    DOE PAGES

    Jones, Aaron M.; Yu, Hongyi; Schaibley, John R.; ...

    2015-12-21

    Photon upconversion is an elementary light-matter interaction process in which an absorbed photon is re-emitted at higher frequency after extracting energy from the medium. Furthermore, this phenomenon lies at the heart of optical refrigeration in solids(1), where upconversion relies on anti-Stokes processes enabled either by rare-earth impurities(2) or exciton-phonon coupling(3). We demonstrate a luminescence upconversion process from a negatively charged exciton to a neutral exciton resonance in monolayer WSe2, producing spontaneous anti-Stokes emission with an energy gain of 30 meV. Polarization-resolved measurements find this process to be valley selective, unique to monolayer semiconductors(4). Since the charged exciton binding energy(5) closelymore » matches the 31 meV A(1)' optical phonon(6-9), we ascribe the spontaneous excitonic anti-Stokes to doubly resonant Raman scattering, where the incident and outgoing photons are in resonance with the charged and neutral excitons, respectively. Additionally, we resolve a charged exciton doublet with a 7 meV splitting, probably induced by exchange interactions, and show that anti-Stokes scattering is efficient only when exciting the doublet peak resonant with the phonon, further confirming the excitonic doubly resonant picture.« less

  6. Excitonic luminescence upconversion in a two-dimensional semiconductor

    SciTech Connect

    Jones, Aaron M.; Yu, Hongyi; Schaibley, John R.; Yan, Jiaqiang; Mandrus, David G.; Taniguchi, Takashi; Watanabe, Kenji; Dery, Hanan; Yao, Wang; Xu, Xiaodong

    2015-12-21

    Photon upconversion is an elementary light-matter interaction process in which an absorbed photon is re-emitted at higher frequency after extracting energy from the medium. Furthermore, this phenomenon lies at the heart of optical refrigeration in solids(1), where upconversion relies on anti-Stokes processes enabled either by rare-earth impurities(2) or exciton-phonon coupling(3). We demonstrate a luminescence upconversion process from a negatively charged exciton to a neutral exciton resonance in monolayer WSe2, producing spontaneous anti-Stokes emission with an energy gain of 30 meV. Polarization-resolved measurements find this process to be valley selective, unique to monolayer semiconductors(4). Since the charged exciton binding energy(5) closely matches the 31 meV A(1)' optical phonon(6-9), we ascribe the spontaneous excitonic anti-Stokes to doubly resonant Raman scattering, where the incident and outgoing photons are in resonance with the charged and neutral excitons, respectively. Additionally, we resolve a charged exciton doublet with a 7 meV splitting, probably induced by exchange interactions, and show that anti-Stokes scattering is efficient only when exciting the doublet peak resonant with the phonon, further confirming the excitonic doubly resonant picture.

  7. Emergency Optically Stimulated Luminescence Dosimetry Using Different Materials

    PubMed Central

    Sholom, S; DeWitt, R; Simon, SL; Bouville, A; McKeever, SWS

    2011-01-01

    Several materials were tested as possible individual emergency dosimeters using Optically Stimulated Luminescence (OSL) as means to assess the exposure. Materials investigated included human nails, business cards and plastic buttons. The OSL properties of these materials were studied in comparison with those of teeth. Most samples revealed OSL signals only after exposure to ionizing radiation; some samples of business cards, however, displayed a strong initial “native” signal (i.e. existing in the samples prior to irradiation). The sensitivity (minimum measurable dose) of the samples was found to vary significantly from sample to sample of the same material and was in the range from several tens of mGy to a few dozens of Gy. The dose response curves were linear for doses below 10 Gy. Fading of the OSL signals was estimated for different lenghts of times and found to be ~95%, 45%, 30% and 15% for samples of teeth, business cards, buttons and nails, respectively, following storage at room temperature in the dark for a period of 3 weeks after exposure. For samples stored under routine laboratory light, fading was much faster and the radiation-induced signals almost disappeared after a few hours of such illumination. It was concluded that the tested materials could be used in triage situations to detect and estimate the possible overexposure of individuals if the measurements can be performed soon enough after exposure. PMID:22125409

  8. The delayed luminescence spectroscopy as tool to investigate the cytotoxic effect on human cancer cells of drug-loaded nanostructured lipid carrier

    NASA Astrophysics Data System (ADS)

    Grasso, R.; Gulino, M.; Scordino, A.; Musumeci, F.; Campisi, A.; Bonfanti, R.; Carbone, C.; Puglisi, G.

    2016-05-01

    The first results concerning the possibility to use Delayed Luminescence spectroscopy to evaluate the in vitro induction of cytotoxic effects on human glioblastoma cells of nanostructured lipid carrier and drug-loaded nanostructured lipid carrier are showed in this contribution. We tested the effects of nanostructured lipid carrier, ferulic acid and ferulic acidloaded nanostructured lipid carrier on U-87MG cell line. The study seems to confirm the ability of Delayed Luminescence to be sensible indicator of alterations induced on functionality of the mitochondrial respiratory chain complex I in U-87MG cancer cells when treated with nanostructured lipid carriers.

  9. Luminescent solar concentrators utilizing stimulated emission.

    PubMed

    Kaysir, Md Rejvi; Fleming, Simon; MacQueen, Rowan W; Schmidt, Timothy W; Argyros, Alexander

    2016-03-21

    Luminescent solar concentrators (LSCs) are an emerging technology that aims primarily to reduce the cost of solar energy, with great potential for building integrated photovoltaic (PV) structures. However, realizing LSCs with commercially viable efficiency is currently hindered by reabsorption losses. Here, we introduce an approach to reducing reabsorption as well as improving directional emission in LSCs by using stimulated emission. Light from a seed laser (potentially an inexpensive laser diode) passes through the entire area of the LSC panel, modifying the emission spectrum of excited dye molecules such that it is spectrally narrower, at wavelengths that minimize reabsorption to allow net gain in the system, and directed towards a small PV cell. A mathematical model, taking into account thermodynamic considerations, of such a system is presented which identifies key parameters and allows evaluation in terms of net effective output power.

  10. Biosensing with Luminescent Semiconductor Quantum Dots

    PubMed Central

    Sapsford, Kim E.; Pons, Thomas; Medintz, Igor L.; Mattoussi, Hedi

    2006-01-01

    Luminescent semiconductor nanocrystals or quantum dots (QDs) are a recently developed class of nanomaterial whose unique photophysical properties are helping to create a new generation of robust fluorescent biosensors. QD properties of interest for biosensing include high quantum yields, broad absorption spectra coupled to narrow size-tunable photoluminescent emissions and exceptional resistance to both photobleaching and chemical degradation. In this review, we examine the progress in adapting QDs for several predominantly in vitro biosensing applications including use in immunoassays, as generalized probes, in nucleic acid detection and fluorescence resonance energy transfer (FRET) - based sensing. We also describe several important considerations when working with QDs mainly centered on the choice of material(s) and appropriate strategies for attaching biomolecules to the QDs.

  11. Luminescent solar concentrator improvement by stimulated emission

    NASA Astrophysics Data System (ADS)

    Kaysir, Md Rejvi; Fleming, Simon; MacQueen, Rowan W.; Schmidt, Timothy W.; Argyros, Alexander

    2015-12-01

    Luminescent solar concentrators (LSCs) offer the prospect of reducing the cost of solar energy, and are a promising candidate for building integrated photovoltaic (PV) structures. However, the realization of commercially viable efficiency of LSCs is currently hindered by reabsorption losses. In this work, a method is introduced for reducing reabsorption as well as improving directional emission in LSCs by using stimulated emission. Light from a seed laser (potentially an inexpensive laser diode) passes through the entire length of the LSC panel, modifying the emission spectrum of excited dye molecules such that it is spectrally narrower, at wavelengths that minimize reabsorption, and directed by the seed laser towards a small target PV cell. A mathematical model of such a system is presented which identifies different physical parameters responsible for the power conversion efficiency and gives the net effective output power.

  12. Towards an optoelectronic luminescent sensing device

    NASA Astrophysics Data System (ADS)

    Papkovsky, Dmitry B.; Ponomarev, Gely V.; Ogurtsov, Vladimir I.; Dvornikov, Alexey A.

    1994-02-01

    The new dye which has improved spectral characteristics synthesized on the basis of platinum complex of the porphyrin-like compound was studied with the view of its application to oxygen sensing. It resulted in a new solid-state oxygen-sensitive material with advanced working characteristics which is highly compatible with excitation with yellow LEDs. This new sensing material makes it possible to develop simple fiber-optoelectronic devices -- prototype oxygen sensors. One of the embodiments was constructed which utilizes powerful yellow LED as a light source, silicone photodiode as a photodetector, and has a fiber-optic output terminated with an active element (oxygen membrane). The electronic scheme of the device provides modulation of LED at a kilohertz range frequency and is capable of measuring specific luminescent signal. The system is now under improvement and optimization with emphasis to lifetime measurements performed by phase method.

  13. Irradiated Shellfish: Identification by Photostimulated Luminescence

    PubMed Central

    Di Schiavi, Maria Teresa; Falconi, Grazia; Verità, Francesca Della; Cavallina, Roberta

    2014-01-01

    The irradiation of food is a technology used in the industry to prevent the deterioration of foodstuff in some countries. The European Community legislation states that each Member State must carry out annual checks on the products during commercialisation. The Istituto Zooprofilattico Sperimentale delle regioni Lazio e Toscana (Rome, Italy) has developed and validated the screening method of photostimulated luminescence UNI EN 13751:2009 to identify irradiated shellfish. A total of 30 tests of shellfish samples, consisting of 22 certified as irradiated and 8 not-irradiated samples, were performed. The validation procedure was based on sensitivity and specificity; the compatibility between the screening method and the reference standard EN 13751:2009 was evaluated. Data were processed: 100% sensitivity and 100% specificity were obtained. Results obtained in our laboratory were perfectly compatible with the reference standard. For this reason, the method has been validated and proved to be suitable for its intended use. PMID:27800335

  14. Video luminescent barometry - The induction period

    NASA Technical Reports Server (NTRS)

    Uibel, Rory H.; Khalil, Gamal; Gouterman, Martin; Gallery, Jean; Callis, James B.

    1993-01-01

    Video monitoring of oxygen quenching of the photoluminescence of platinum octaethylporphyrin (PtOEP) in silicone polymer resin may be used to measure pressure distribution over an airfoil. A continuous increase of the luminescence intensity of PtOEP on exposure to the exciting light is known as the induction effect. The effect of several factors on PtOEP photoluminescence and the induction effect was investigated. The experimental apparatus is described and results are presented. It was observed that the relative induction amplitude and induction time increase at higher oxygen pressure and with thicker films. These observations may be explained if the singlet oxygen produced by oxygen quenching is consumed by the polymer and is therefore unavailable for further quenching. Researchers using this method for measuring pressure distribution on airfoil surfaces should be aware of the induction effect and its implications.

  15. Luminescence Rings in Quantum Well Structures

    NASA Astrophysics Data System (ADS)

    Denev, S.; Liu, Y.; Snoke, D.; Rapaport, R.; Chen, Gang; Simon, S.; Pfeiffer, L.; West, K.

    2004-03-01

    An unique ring-shaped luminescence pattern with size of hundreds of microns to millimeters has been observed in GaAs-based quantum well structures excited by weak laser light [1]. The ring persists up to high temperatures, and its size can be manipulated by the laser power, electric field, external stress or magnetic field. We give a detailed description of the effect and discuss various proposed explanations including an optical effect, diffusion and excitonic superfluidity. A realistic explanation based on a simple, nonlinear model of charge separation is proposed, and numerical results from the model are compared to the experiment. This work has been supported by the National Science Foundation under grant No. DMR-0102457 and by the Department of Energy under grant No. DE-FG0299ER45780 [1] D. Snoke, S. Denev, Y. Liu, L. Pfeiffer, and K. West, "Long-range Transport in Excitonic Dark States in Coupled Quantum Wells," Nature 418, 754 (2002).

  16. Developing luminescent silver nanodots for biological applications.

    PubMed

    Choi, Sungmoon; Dickson, Robert M; Yu, Junhua

    2012-03-07

    Though creation and characterization of water soluble luminescent silver nanodots were achieved only in the past decade, a large variety of emitters in diverse scaffolds have been reported. Photophysical properties approach those of semiconductor quantum dots, but relatively small sizes are retained. Because of these properties, silver nanodots are finding ever-expanding roles as probes and biolabels. In this critical review we revisit the studies on silver nanodots in inert environments and in aqueous solutions. The recent advances detailing their chemical and physical properties of silver nanodots are highlighted with an effort to decipher the relations between their chemical/photophysical properties and their structures. The primary results about their biological applications are discussed here as well, especially relating to their chemical and photophysical behaviours in biological environments (216 references).

  17. Luminescence of erbium ions in tellurite glasses

    NASA Astrophysics Data System (ADS)

    Savikin, Alexander P.; Grishin, Igor A.; Sharkov, Valery V.; Budruev, Andrei V.

    2013-11-01

    Optical characteristics of new generation of tellurite glasses having high stability against crystallization have been studied. As the initial reagents for the glasses synthesis on the base of tellurium oxide (TeO2) there were used such oxides as WO3, MoO3, La2O3, Li2CO3, ZnO—Bi2O2CO3 and active components such as high purity Er2O3, Yb2O3, ErF3 and YbF3. Intensities of luminescence at 1.53 µm of the erbium ions were determined after excitation at 975 nm. Experimental data obtained have shown the possibility to use the studied glasses doped by Er3+ and Yb3+ as active elements for fiber and integrated optics.

  18. Dynamics of polydots: Soft luminescent polymeric nanoparticles

    SciTech Connect

    Maskey, Sabina; Osti, Naresh C.; Grest, Gary S.; Perahia, Dvora

    2016-03-04

    The conformation and dynamics of luminescent polymers collapsed into nanoparticles or polydots were studied using fully atomistic molecular dynamics (MD) simulations, providing a first insight into their internal dynamics. Controlling the conformation and dynamics of confined polymers is essential for realization of the full potential of polydots in nanomedicine and biotechnology. Specifically, the shape and internal dynamics of polydots that consist of highly rigid dialkyl p-phenylene ethynylene (PPE) are probed as a function of temperature. At room temperature, the polydots are spherical without any correlations between the aromatic rings on the PPE backbone. With increasing temperature, they expand and become slightly aspherical; however, the polymers remain confined. The coherent dynamic structure factor reveals that the internal motion of the polymer backbone is arrested, and the side chains dominate the internal dynamics of the polydots. Lastly, these new soft nanoparticles retain their overall shape and dynamics over an extended temperature range, and their conformation is tunable via their degree of expansion.

  19. Luminescence nanocrystals for solar cell enhancement.

    PubMed

    Liu, Shu-Man; Chen, Wei; Wang, Zhan-Guo

    2010-03-01

    Semiconductor nanocrystals (NCs) prepared by wet-chemical routes have been proposed as an attractive candidate for fabrication of the third-generation thin-film solar cells due to their quantum confinement effects and excellent dispersion ability in polymer films. However, to date, a solar cell incorporating semiconductor NCs in the photoactive layer still has rather low efficiency due to the low carrier mobility of the non-continued NC phase and the possible radiative recombination in NCs. To avoid these disadvantages, NCs have been proposed and applied as a luminescent species in a passive photon converting layer to modify the solar spectrum before the light enters the photovoltaic device. Photon conversion processes, including up-conversion, down-conversion, and down-shifting, have been observed in various colloidal NC samples and have great potential to enhance photovoltaic performance when applied to the existing single-junction solar cells or narrow-band molecular-based devices.

  20. Detection of biological aerosols by luminescence techniques

    NASA Astrophysics Data System (ADS)

    Stopa, Peter J.; Tieman, Darlene; Coon, Phillip A.; Paterno, Dorothea A.; Milton, Maurice M.

    1999-12-01

    Luciferin-Luciferase (L-L) luminescence techniques were used to successfully measure adenosine triphosphate (ATP) (pg/ml) in concentrated aerosol samples containing either vegetative bacterial cells or spores. Aerosols were collected with wet and dry sampling devices. Evaluation for the presence of total bio-mass from bacterial and non-bacterial sources of ATP was achieved by suspending the collected aerosol samples in phosphate buffered saline (PBS), pipeting a 50-(mu) l aliquot of the PBS suspension into a FiltravetteTM, and then adding bacterial releasing agent (BRA). The sample was then reacted with L-L, and the resulting Relative Luminescence Units (RLU's), indicative of ATP from all sources, were measured. Bacterial cells were enumerated with the additional application of a wash with somatic cell releasing agent (SRA) to remove any interferences and non-bacterial sources of ATP prior to BRA application. This step removes interfering substances and non-bacterial sources of ATP. For spore analysis, an equi-volume sample of the PBS suspension was added to an equi-volume of trypticase soy broth (TSB), incubated at 37 C for 15 minutes, and processed using methods identical to bacterial cell analysis. Using these technique we were able to detect Bacillus subtilin variation niger, formerly known as Bacillus globigii (BG), in aerosol samples at concentrations greater than or equal to 105 colony forming units (CFU) per ml. Results of field and chamber trials show that one can detect the presence of bacterial and non-bacterial sources of ATP. One can also differentiate spore and vegetative bacterial cells. These techniques may be appropriate to situations where the measurement of bacterial aerosols is needed.

  1. Genetically engineered luminescent proteins in biosensing

    NASA Astrophysics Data System (ADS)

    Rowe, Laura; Ensor, Mark; Scott, Daniel; Deo, Sapna; Daunert, Sylvia

    2006-02-01

    Luminescent proteins originally isolated from marine or terrestrial organisms have played a key role in the development of several biosensing systems. These proteins have been used in a variety of applications including, immunoassays, binding assays, cell-based sensing, high throughput screening, optical imaging, etc. Among the luminescent proteins isolated, the bioluminescent protein aequorin has been one of the proteins at the forefront in terms of its use in a vast number of biosensing systems. In our laboratory, we have employed aequorin as a label in the development of highly sensitive assays through chemical and genetic modifications from single step analysis of physiologically important molecules in biological fluids. An important aspect of optimizing these assays for clinical use involves understanding the stability of the various aequorin variants that are available. To this end we have designed several stability studies involving three important aequorin mutants, Mutant S, Mutant 5, and Mutant 53. The cysteine free aequorin, Mutant S, has been the most ubiquitously used aequorin variant in our laboratory because of its increased stability and activity as compared to native aequorin. Mutant 5 and Mutant 53 contain a single cyteine residue at position 5 and 53 in the protein, respectively. Because of the presence of a single cysteine residue, Mutant 5 and Mutant 53 both can be site-specifically conjugated. This site specific conjugation capability gives Mutant 5 and Mutant 53 an advantage over native aequorin when developing assays. Additional studies optimizing the expression, purification, and charging of aequorin Mutant S were also performed. A thorough understanding of the efficient expression, purification, and storage of these aequorin mutants will allow for the more practical utilization of these mutants in the development of future biosensing systems.

  2. Topaz and Kyanite Luminescence Under High Pressure

    NASA Astrophysics Data System (ADS)

    O'Bannon, E. F., III; Williams, Q. C.

    2014-12-01

    The luminescence spectra of Cr3+ in heat-treated topaz Al2SiO4(OH,F)2 and natural kyanite Al2SiO5 were measured from 650 - 800 nm in a hydrostatic environment up to pressures of 15 GPa. The R1 and R2 peaks of topaz shift at average rates of 0.30 nm/GPa and 0.22 nm/GPa, respectively, implying that the deformation of the Cr3+ octahedra increases with pressure. Three peaks are fit under each R line of topaz at both room and high pressure, and these peaks are associated with different Al sites into which the Cr substitutes. The shift of the R lines in topaz under pressure is remarkably linear, which appears to be a general feature of many Cr3+-bearing oxides: the underlying cause of this linearity may lie in anharmonic coupling with lattice vibrations. In this context, we also characterize the frequency shifts of two vibronic peaks within topaz. The R1 and R2 peaks of kyanite shift at 0.37 nm/GPa and 0.88 nm/GPa respectively. Two peaks are fit under R1 and three peaks are fit under R2 of kyanite at both room and high pressure; this result is also consistent with three different Cr3+ sites in this material. The R lines in kyanite are notably optically anisotropic, depending strongly on crystallographic orientation: this is most strongly manifested in the R2 peak. The Cr3+ luminescence in these materials provides a sensitive probe of pressure-dependent shifts in the local geometry of the Al-sites in these materials, which are analyzed in the context of previous single-crystal x-ray diffraction measurements.

  3. Near-Infrared Quantum Cutting Long Persistent Luminescence

    NASA Astrophysics Data System (ADS)

    Zou, Zehua; Feng, Lin; Cao, Cheng; Zhang, Jiachi; Wang, Yuhua

    2016-05-01

    By combining the unique features of the quantum cutting luminescence and long persistent luminescence, we design a new concept called “near-infrared quantum cutting long persistent luminescence (NQPL)”, which makes it possible for us to obtain highly efficient (>100%) near-infrared long persistent luminescence in theory. Guided by the NQPL concept, we fabricate the first NQPL phosphor Ca2Ga2GeO7:Pr3+,Yb3+. It reveals that both the two-step energy transfer of model (I) and the one-step energy transfer of model (IV) occur in 3P0 levels of Pr3+. Although the actual efficiency is not sufficient for the practical application at this primitive stage, this discovery and the associated materials are still expected to have important implications for several fields such as crystalline Si solar cells and bio-medical imaging.

  4. Near-Infrared Quantum Cutting Long Persistent Luminescence

    PubMed Central

    Zou, Zehua; Feng, Lin; Cao, Cheng; Zhang, Jiachi; Wang, Yuhua

    2016-01-01

    By combining the unique features of the quantum cutting luminescence and long persistent luminescence, we design a new concept called “near-infrared quantum cutting long persistent luminescence (NQPL)”, which makes it possible for us to obtain highly efficient (>100%) near-infrared long persistent luminescence in theory. Guided by the NQPL concept, we fabricate the first NQPL phosphor Ca2Ga2GeO7:Pr3+,Yb3+. It reveals that both the two-step energy transfer of model (I) and the one-step energy transfer of model (IV) occur in 3P0 levels of Pr3+. Although the actual efficiency is not sufficient for the practical application at this primitive stage, this discovery and the associated materials are still expected to have important implications for several fields such as crystalline Si solar cells and bio-medical imaging. PMID:27143282

  5. Selective excitation of the yellow luminescence of GaN

    SciTech Connect

    Colton, J.S.; Yu, P.Y.; Teo, K.L.; Weber, E.R.; Grzegory, I.; Uchida, K.

    1999-07-01

    The yellow luminescence of n-type GaN has been studied with selective excitation using a combination of Ar ion and dye lasers. Narrower structures whose peak energies follow the excitation photon energy over the width of the yellow luminescence have been observed. Unlike the yellow luminescence excited by above band gap excitations, these fine structures exhibits thermal activated quenching behavior. We propose that these fine structures are due to emission occurring at complexes of shallow donors and deep acceptors which can be resonantly excited by photons with energies below the band gap. The activation energy deduced from their intensity is that for delocalization of electrons out of the complexes. Our results therefore suggest that there is more than one recombination channel (usually assumed to be due to distant donor-acceptor pairs) to the yellow luminescence in GaN.

  6. Luminescent coupling in planar opto-electronic devices

    SciTech Connect

    Wilkins, Matthew Valdivia, Christopher E.; Gabr, Ahmed M.; Hinzer, Karin; Masson, Denis; Fafard, Simon

    2015-10-14

    Effects of luminescent coupling are observed in monolithic 5 V, five-junction GaAs phototransducers. Power conversion efficiency was measured at 61.6% ± 3% under the continuous, monochromatic illumination for which they were designed. Modeling shows that photon recycling can account for up to 350 mV of photovoltage in these devices. Drift-diffusion based simulations including a luminescent coupling term in the continuity equation show a broadening of the internal quantum efficiency curve which agrees well with experimental measurements. Luminescent coupling is shown to expand the spectral bandwidth of the phototransducer by a factor of at least 3.5 for devices with three or more junctions, even in cases where multiple absorption/emission events are required to transfer excess carriers into the limiting junction. We present a detailed description of the novel luminescent coupling modeling technique used to predict these performance enhancements.

  7. Fundamental and applied aspects of luminescence of colloidal quantum dots

    NASA Astrophysics Data System (ADS)

    Razumov, V. F.

    2017-03-01

    The spectral luminescent characteristics of colloidal quantum dots as a new class of luminophores are discussed and state-of-the-art investigations, problems, and prospects for their applications are considered.

  8. Enhancing the efficiency of luminescent solar concentrators (LSCs)

    NASA Astrophysics Data System (ADS)

    Assadi, M. Khalaji; Hanaei, H.; Mohamed, Norani Muti; Saidur, R.; Bakhoda, Shokoufeh; Bashiri, Robabeh; Moayedfar, M.

    2016-09-01

    Recent developments in the endeavor to enhance the efficiency of luminescent solar concentrators (LSCs) are presented in this paper along with an analysis of LSC devices. In recent years, several experimental and numerical research works have been carried out to improve the performance of LSCs in different ways. LSCs date back to the 1970s and comprise an extremely interesting notion of solar cells for various reasons. First, LSCs are cost-competitive and function in diffuse light, and as such, it is not necessary to use expensive solar tracking devices. Second, luminescence facilitates the cells to gather only cold light, which results in higher PV efficiency. LSCs generally consist of transparent polymer sheets doped with luminescent species. The luminescent species absorb incident sunlight and emit it with high quantum efficiency, such that the emitted light is trapped in the sheet and travels to the edges where the solar cells can collect it.

  9. Can subglacial processes reset the luminescence of basal sediment?

    NASA Astrophysics Data System (ADS)

    Swift, Darrel; Bateman, Mark; Piotrowski, Jan

    2010-05-01

    Analysis of the natural luminescence of basal sediment from Haut Glacier d'Arolla, Switzerland (Swift et al., under revision) has revived speculation that erosion and/or sediment transport in the subglacial environment may constitute effective luminescence resetting mechanisms. The plausibility of these resetting mechanisms rests on the presumption that luminescence signals can be reset if sediment grains are exposed to sufficient stress. The ice-bedrock contact zone of active glacial systems and the shear zones of active fault systems have been cited as environments where shearing has the potential to reset luminescence; however, laboratory studies that have investigated the effects of shearing on luminescence have produced conflicting results. We present the first results from a laboratory-based project that aims to determine the efficacy of resetting in the subglacial environment by shearing sediment under conditions representative of the ice-bedrock contact zone of active glacial systems. Preliminary luminescence data will be shown from an initial experiment that aims to quantify the effect of shearing on the luminescence of quartz. Homogenous medium-sand was obtained for the experiment from relict dune systems that possess substantial natural luminescence (we anticipate that glacial sediments with a wider range of grain sizes will be used in later experiments). Shearing was conducted using a state-of-the-art ring-shear apparatus using an imposed normal stress of 50 kPa at a shearing rate of 1 mm per minute for a distance of ~ 1200 mm, with samples for luminescence analyses taken from the shearing zone at pre-defined intervals. It is anticipated that further experiments using a range of imposed normal stresses and further analyses of changes in the luminescence and surface microtexture of grains in specific grain-size fractions will elucidate and quantify the specific nature of the resetting mechanism. Swift, D.A., Sanderson, D.C.W., Nienow, P.W., Bingham, R

  10. Luminescence dates for the Paleoindian site of Pedra Pintada, Brazil

    NASA Astrophysics Data System (ADS)

    Michab, M.; Feathers, J. K.; Joron, J.-L.; Mercier, N.; Selo, M.; Valladas, H.; Valladas, G.; Reyss, J.-L.; Roosevelt, A. C.

    Dates are presented for the Paleoindian levels of Pedra Pintada cave in Brazil, based on the thermoluminescence (TL) and optically stimulated luminescence (OSL) study of ten specimens of heated siliceous stones and three of sand, respectively. Also discussed are the details of preliminary mineralogical, radiographic, and analytical work done on the lithic specimens in France and the OSL work done on the sediments in the US. The luminescence dates are in agreement with radiocarbon dates for the same strata.

  11. Influence of excitonic effects on luminescence quantum yield in silicon

    NASA Astrophysics Data System (ADS)

    Sachenko, A. V.; Kostylyov, V. P.; Vlasiuk, V. M.; Sokolovskyi, I. O.; Evstigneev, M.

    2017-03-01

    Nonradiative exciton lifetime in silicon is determined by comparison of the experimental and theoretical curves of bulk minority charge carriers lifetime on doping and excitation levels. This value is used to analyze the influence of excitonic effects on internal luminescence quantum yield at room temperature, taking into account both nonradiative and radiative exciton lifetimes. A range of Shockley-Hall-Reed lifetimes is found, where excitonic effects lead to an increase of internal luminescence quantum yield.

  12. Luminescence-based optical sensor systems for monitoring water parameters

    NASA Astrophysics Data System (ADS)

    Lobnik, Aleksandra; Turel, Matejka; Korent, Špela Mojca

    2007-06-01

    Lanthanide-sensitized luminescence is very attractive because the intramolecular energy transfers between the absorbing ligand and the luminescent ion results in strong narrow-band fluorescence with a large Stokes' shift and long decay times. We will report about several sensor systems based either on sol-gel materials or lanthanide chelates for monitoring and controlling water parameters, such as heavy metals, amines, phosphates.

  13. Luminescent properties of cadmium selenide quantum dots in fluorophosphate glasses

    NASA Astrophysics Data System (ADS)

    Lipatova, Zh. O.; Kolobkova, E. V.; Babkina, A. N.

    2016-11-01

    The optical properties of fluorophosphate glasses with CdSe quantum dots are studied. Secondary heat treatment at a temperature exceeding the glass transition temperature resulted in the formation of quantum dots with sizes of 3.7-6.2 nm. The influence of the semiconductor component concentration on the spectral-luminescent characteristics of glasses is shown. It is experimentally demonstrated that glasses with a lower CdSe concentration have a higher absolute luminescence quantum yield.

  14. Polarization Effects in the Luminescence of Cadmium Selenide Electrodes.

    DTIC Science & Technology

    1983-09-29

    UWIS/DC/TR-83/3 Polarization Effects in the Luminescence of Cadmium Selenide Electrodes by Holger H. Streckert, Hal Van Ryswyk, Richard N. Biagioni...the Luminescence of Cadmium Selenide Electrodes______________ S. PERFORMING ORG. REPORT NUMBER 7. AUT,4OR(e) S. CONTRACT OR GRANT NUMBER~q) Holger H...Continue an reverse aide if necieemy arid Identify, by block number) Cadmium selenide electrodes, photoluminescence, electroluminescence, polarized

  15. Lanthanide luminescence enhancements in porous silicon resonant microcavities.

    PubMed

    Jenie, S N Aisyiyah; Pace, Stephanie; Sciacca, Beniamino; Brooks, Robert D; Plush, Sally E; Voelcker, Nicolas H

    2014-08-13

    In this paper, the covalent immobilization and luminescence enhancement of a europium (Eu(III)) complex in a porous silicon (pSi) layer with a microcavity (pSiMC) structure are demonstrated. The alkyne-pendant arm of the Eu(III) complex was covalently immobilized on the azide-modified surface via ligand-assisted "click" chemistry. The design parameters of the microcavity were optimized to obtain an efficient luminescence-enhancing device. Luminescence enhancements by a factor of 9.5 and 3.0 were observed for Eu(III) complex bound inside the pSiMC as compared to a single layer and Bragg reflector of identical thickness, respectively, confirming the increased interaction between the immobilized molecules and the electric field in the spacer of the microcavity. When comparing pSiMCs with different resonance wavelength position, luminescence was enhanced when the resonance wavelength overlapped with the maximum emission wavelength of the Eu(III) complex at 614 nm, allowing for effective coupling between the confined light and the emitting molecules. The pSiMC also improved the spectral color purity of the Eu(III) complex luminescence. The ability of a pSiMC to act as an efficient Eu(III) luminescence enhancer, combined with the resulting sharp linelike emission, can be exploited for the development of ultrasensitive optical biosensors.

  16. Luminescent molecular rods - transition-metal alkynyl complexes.

    PubMed

    Yam, Vivian Wing-Wah; Wong, Keith Man-Chung

    2005-01-01

    A number of transition-metal complexes have been reported to exhibit rich luminescence, usually originating from phosphorescence. Such luminescence properties of the triplet excited state with a large Stoke's shift, long lifetime, high luminescence quantum yield as well as lower excitation energy, are envisaged to serve as an ideal candidate in the area of potential applications for chemosensors, dye-sensitized solar cells, flat panel displays, optics, new materials and biological sciences. Organic alkynes (poly-ynes), with extended or conjugatedπ-systems and rigid structure with linear geometry, have become a significant research area due to their novel electronic and physical properties and their potential applications in nanotechnology. Owing to the presence of unsaturated sp-hybridized carbon atoms, the alkynyl unit can serve as a versatile building block in the construction of alkynyl transition-metal complexes, not only throughσ-bonding but also viaπ-bonding interactions. By incorporation of linear alkynyl groups into luminescent transition-metal complexes, the alkynyl moiety with goodσ-donor,π-donor andπ-acceptor abilities is envisaged to tune or perturb the emission behaviors, including emission energy (color), intensity and lifetime by its role as an auxiliary ligand as well as to govern the emission origin from its direct involvement. This review summarizes recent efforts on the synthesis of luminescent rod-like alkynyl complexes with different classes of transition metals and details the effects of the introduction of alkynyl groups on the luminescence properties of the complexes.

  17. Flight testing of a luminescent surface pressure sensor

    NASA Technical Reports Server (NTRS)

    Mclachlan, B. G.; Bell, J. H.; Espina, J.; Gallery, J.; Gouterman, M.; Demandante, C. G. N.; Bjarke, L.

    1992-01-01

    NASA ARC has conducted flight tests of a new type of aerodynamic pressure sensor based on a luminescent surface coating. Flights were conducted at the NASA ARC-Dryden Flight Research Facility. The luminescent pressure sensor is based on a surface coating which, when illuminated with ultraviolet light, emits visible light with an intensity dependent on the local air pressure on the surface. This technique makes it possible to obtain pressure data over the entire surface of an aircraft, as opposed to conventional instrumentation, which can only make measurements at pre-selected points. The objective of the flight tests was to evaluate the effectiveness and practicality of a luminescent pressure sensor in the actual flight environment. A luminescent pressure sensor was installed on a fin, the Flight Test Fixture (FTF), that is attached to the underside of an F-104 aircraft. The response of one particular surface coating was evaluated at low supersonic Mach numbers (M = 1.0-1.6) in order to provide an initial estimate of the sensor's capabilities. This memo describes the test approach, the techniques used, and the pressure sensor's behavior under flight conditions. A direct comparison between data provided by the luminescent pressure sensor and that produced by conventional pressure instrumentation shows that the luminescent sensor can provide quantitative data under flight conditions. However, the test results also show that the sensor has a number of limitations which must be addressed if this technique is to prove useful in the flight environment.

  18. Instantaneous frequency based newborn EEG seizure characterisation

    NASA Astrophysics Data System (ADS)

    Mesbah, Mostefa; O'Toole, John M.; Colditz, Paul B.; Boashash, Boualem

    2012-12-01

    The electroencephalogram (EEG), used to noninvasively monitor brain activity, remains the most reliable tool in the diagnosis of neonatal seizures. Due to their nonstationary and multi-component nature, newborn EEG seizures are better represented in the joint time-frequency domain than in either the time domain or the frequency domain. Characterising newborn EEG seizure nonstationarities helps to better understand their time-varying nature and, therefore, allow developing efficient signal processing methods for both modelling and seizure detection and classification. In this article, we used the instantaneous frequency (IF) extracted from a time-frequency distribution to characterise newborn EEG seizures. We fitted four frequency modulated (FM) models to the extracted IFs, namely a linear FM, a piecewise-linear FM, a sinusoidal FM, and a hyperbolic FM. Using a database of 30-s EEG seizure epochs acquired from 35 newborns, we were able to show that, depending on EEG channel, the sinusoidal and piecewise-linear FM models best fitted 80-98% of seizure epochs. To further characterise the EEG seizures, we calculated the mean frequency and frequency span of the extracted IFs. We showed that in the majority of the cases (>95%), the mean frequency resides in the 0.6-3 Hz band with a frequency span of 0.2-1 Hz. In terms of the frequency of occurrence of the four seizure models, the statistical analysis showed that there is no significant difference( p = 0.332) between the two hemispheres. The results also indicate that there is no significant differences between the two hemispheres in terms of the mean frequency ( p = 0.186) and the frequency span ( p = 0.302).

  19. First principles characterisation of aluminium trifluoride catalysts

    NASA Astrophysics Data System (ADS)

    Bailey, C. L.; Mukhopadhyay, S.; Wander, A.; Searle, B. G.; Harrison, N. M.

    2008-06-01

    The recently discovered high surface area AlF3 catalyst is characterised with respect to surface composition and structure using calculations based on density functional theory. Under typical reaction conditions the surfaces are found to expose five fold coordinated Al reaction centres and to preferentially adsorb water. The acidic centres are probed using NH3 adsorption which binds strongly indicating strong Lewis acidity. The predicted temperature probed desorption spectrum has features from competing surfaces and features due to strong intermolecular interactions, which are used to interpret the observed spectrum.

  20. Isolation and characterisation of plant defensins from seeds of Asteraceae, Fabaceae, Hippocastanaceae and Saxifragaceae.

    PubMed

    Osborn, R W; De Samblanx, G W; Thevissen, K; Goderis, I; Torrekens, S; Van Leuven, F; Attenborough, S; Rees, S B; Broekaert, W F

    1995-07-17

    From seeds of Aesculus hippocastanum, Clitoria ternatea, Dahlia merckii and Heuchera sanguinea five antifungal proteins were isolated and shown to be homologous to plant defensins previously characterised from radish seeds and gamma-thionins from Poaceae seeds. Based on the spectrum of their antimicrobial activity and the morphological distortions they induce on fungi the peptides can be divided into two classes. The peptides did not inhibit any of three different alpha-amylases.

  1. [Conditions that influence bacterial luminescence in the presence of blood serum].

    PubMed

    Deriabin, D G; Poliakov, E G

    2005-01-01

    Conditions that influence the luminescence of natural and recombinant luminescent bacteria in the presence of blood serum were studied. In general, blood serum quenched the luminescence of the marine Photobacterium phosphoreum and the recombinant Escherichia coli strains harboring the luminescent system genes of Photobacterium leiognathi, but enhanced the luminescence of the soil bacterium Photorhabdus luminescens Zm1 and the recombinant E. coli strain harboring the lux operon of P. luminescens Zm1. The quenching effect of blood serum increased with its concentration and the time and temperature of incubation. The components of blood serum that determine the degree and specificity of its action on bacterial luminescence were identified.

  2. Luminescence of phosphorus containing oxide materials: Crystalline SiO2-P and 3P2O5ṡ7SiO2; CaOṡP2O5; SrOṡP2O5 glasses

    NASA Astrophysics Data System (ADS)

    Trukhin, A. N.; Smits, K.; Jansons, J.; Berzins, D.; Chikvaidze, G.; Griscom, D. L.

    2014-10-01

    Luminescence of phosphate glasses such as CaOṡP2O5 and SrOṡP2O5 is compared with that of phosphorus doped crystalline α-quartz and phosphosilicate glass with content 3P2O5ṡ7SiO2. Water & OH groups are found by IR spectra in these materials. The spectrum of luminescence contains many bands in the range 1.5 - 5.5 eV. The luminescence bands in UV range at 4.5-5 eV are similar in those materials. Decay duration in exponential approximation manifests a time constant about 37 ns. Also a component in μs range was detected. PL band of μs component is shifted to low energy with respect to that of ˜37 ns component. This shift is about 0.6 eV. It is explained as singlet-triplet splitting of excited state. Below 14 K increase of luminescence kinetics duration in μs range was observed and it was ascribed to zero magnetic field splitting of triplet excited state of the center. Yellow-red luminescence was induced by irradiation in phosphorus doped crystalline α-quartz, phosphosilicate glasses. The yellowl uminescence contains two bands at 600 and 740 nm. Their decay is similar under 193 nm laser and may be fitted with the first order fractal kinetics or stretched exponent. Thermally stimulated luminescence contains only band at 600 nm. The 248 nm laser excites luminescence at 740 nm according to intra center process with decay time constant about 4 ms at 9 K. Both type of luminescence UV and yellow were ascribed to different defects containing phosphorus. P-doped α-quartz sample heated to 550 co become opalescent. Ir spectra related to water & OH groups are changed. Photoluminescence intensity of all three bands, UV (250 nm), yellow (600 nm) and red (740 nm) strongly diminished and disappeared after heating to 660 C°. Radiation induced red luminescence of non-bridging oxygen luminescence center (NBO) appeared in crystal after heat treatment. We had observed a crystalline version of this center (l. Skuja et al, Nuclear Instruments and Methods in Physics Research B

  3. Luminescence dating of ancient Darhad basin, Mongolia

    NASA Astrophysics Data System (ADS)

    Cheul Kim, Jin; Yi, Sangheon; Lim, Jaesoo; Kim, Ju-Yong

    2016-04-01

    . Thus, age control on existing 14C ages from this site is limited, chronological interpretation based on the 14C ages is still incomplete in Hodon outcrop sediments. OSL (Optically Stimulated Luminescence) is an alternative method for dating to overcome the problems associated with 14C methods. OSL has been extensively used for dating arctic sediments (Thomas et al., 2006; more). Previous optical ages on Darhad paleolake sediments obtained using IRSL (Infrared-stimulated luminescence) on feldspars (Gillespie et al., 2008; Batbaatar et al., 2009). Feldspar has much brighter luminescence than quartz, while the OSL signal of feldspars bleaches at least one order of magnitude slower than the OSL signal of quartz (Godfrey-Smith et al., 1988; Huntly and Lamothe, 2001; Mauz and Bungenstock, 2007; Kim et al., 2012). In glaciofluvial, glaciolacustrine environments, inadequate bleaching of the OSL signal is known to be a potential problem of burial ages (Thomas et al., 2006). OSL dating of permafrost deposits may also involve uncertainty about the inhomogeneous radiation field surrounding the dosimeter and the absorption of ionizing energy alternately by water and ice in a not-constant pore volume (Haeberli et al., 2003). In this study, we test the applicability of quartz OSL dating for the uppermost paleolake sediments in the Hodon outcrop of the Darhad basin. The OSL results were systematically compared with additional radiocarbon ages from wood fragments to conclude the reliability of the OSL dates and to construct intensive chronology for Late-Pleistocene Darhad paleolake. To evaluate the time of recent expansion of the paleolake, the northern piedmont (Talyn outcrop) of the basin was dated by OSL.

  4. Measurement of solid-state optical refrigeration by two-band differential luminescence thermometry

    SciTech Connect

    Hehlen, Markus P; Epstein, Richard I; Patterson, Wendy M; Sheik - Bahae, Mansoor; Seletskiy, D V

    2009-01-01

    We present a non-contact spectroscopic teclmique for the measurement of laser-induced temperature changes in solids. Two-band differential luminescence thermometry (TBDLT) achieves a sensitivity of {approx}7 mK and enables precise measurement of the net quantum efficiency of optical refrigerator materials. TBDLT detects internal temperature changes by decoupling surface and bulk heating effects via time-resolved luminescence spectroscopy. Several Yb{sup 3+}-doped fluorozirconate (ZBLANI) glasses fabricated from precursors of varying purity and by different processes are analyzed in detail. A net quantum efficiency of 97.39% at 238 K (at a pump wavelength of 1020.5 nm) is found for a ZBLANI:1%Yb{sup 3+} laser-cooling sample produced from metal fluoride precursors that were purified by chelate-assisted solvent extraction and dried in hydrofluoric gas. In comparison, a ZBLANI:1%Yb{sup 3+} sample produced from commercial-grade metal fluoride precursors showed pronounced laser-induced heating that is indicative of a substantially higher impurity concentration. TBDLT enables rapid and sensitive benchmarking of laser-cooling materials and provides critical feedback to the development and optimization of high-performance optical cryocooler materials.

  5. The Luminescence and ESR of a Synthetic Emerald and the Natural Ones Mined from Santa Terezinha in Brazil

    NASA Astrophysics Data System (ADS)

    Ohkura, Hiroshi; Hashimoto, Hisashi; Mori, Yuzo; Chiba, Yoshinori; Isotani, Sadao

    1987-09-01

    Both the luminescence and ESR of a synthetic (KC-) emerald and a natural (ST-) type, mined from Santa Terezinha in Brazil, have been studied. The luminescence spectra of the impurity Cr3+ ions in both emeralds consist of two zerophonon lines followed by satellite bands. The satellite band of the ST-emerald shows huge intensity and broad width compared with that of the KC-emerald. The ESR of the Cr3+ ions in the ST-emerald is specific in the anisotropy of the g-factor and has a wider peak-to-peak value than the KC-emerald. We propose that these differences are caused by an interaction induced by the presence of a large number of impurity Fe3+ ions contained in the ST-emerald. The existence of Fe3+ and their concentrations were estimated by ESR.

  6. X-ray spectroscopy studies of nonradiative energy transfer processes in luminescent lanthanide materials

    NASA Astrophysics Data System (ADS)

    Pacold, Joseph I.

    having a strong charge-transfer character. A second primary result comes from an an x-ray excited optical luminescence (XEOL) study that demonstrates, for the first time, that the high flux of modern synchrotron light sources can induce high fractional populations of excited states in trivalent lanthanide phosphors. In this work we have identified the leading-order nonlinear-response mechanism by drawing on strong similarities between XEOL and cathodoluminescence. These results establish the groundwork for studies that would allow deeper inquiry into energy-transfer mechanisms through time-resolved x-ray pump/optical-probe spectroscopies, through time-resolved x-ray emission spectroscopy, or through quantifying of higher-order nonlinear effects at further-enhanced fractional excitation levels. The above scientific results are augmented by a supporting effort in instrumental methodology. This includes the development of high-efficiency x-ray emission spectrometers and their use in collaborations to study pressure-induced changes in f-electron physics and to characterize the intermediate states that occur after photoexcitation of the photosystem-II protein.

  7. Luminescence of some airborne plant materials

    NASA Astrophysics Data System (ADS)

    Satterwhite, Melvin B.

    1997-07-01

    The objective of this study was to describe the excitation- emission spectra of seed pubescence, pollen and spores, and senesced plant materials that could be carried in the air column. Reference samples were a mature green-colored corn leaf, green-, yellow- and brown-colored soybean leaves, cellulose, commercial grade cotton batting and a soil. Spectral luminescence signatures were collected over the 300 to 800 nanometer region using a scanning spectrofluorometer. The excitation-emission spectra were broadband emission centroids in the 400-nm to 600-nm spectrum. Emission maxima were associated with the 440-nm, 470-nm and 370-nm excitation bands and the 455-nm to 590-nm emission bands. The coma of milkweed, silkvine, cotton (raw), cottonwood seeds and yellow- colored pollen and spores were highly fluorescent. The pappus of thistles, dandelion and goat's beard seeds and newly senesced grass leaves and glumes had moderate to high fluorescence. Dark brown-colored mushroom spores and weathered, senesced plant materials had low fluorescence. The emission spectra resembled that of regent, microcrystalline cellulose although impurities incorporated within the plant materials altered their emission intensities from that of cellulose. Moderate to low emissions were from tan- to dark brown-colored materials, whereas the white-colored or light, tan-colored materials had high emissions.

  8. Gated Luminescence Imaging of Silicon Nanoparticles.

    PubMed

    Joo, Jinmyoung; Liu, Xiangyou; Kotamraju, Venkata Ramana; Ruoslahti, Erkki; Nam, Yoonkey; Sailor, Michael J

    2015-06-23

    The luminescence lifetime of nanocrystalline silicon is typically on the order of microseconds, significantly longer than the nanosecond lifetimes exhibited by fluorescent molecules naturally present in cells and tissues. Time-gated imaging, where the image is acquired at a time after termination of an excitation pulse, allows discrimination of a silicon nanoparticle probe from these endogenous signals. Because of the microsecond time scale for silicon emission, time-gated imaging is relatively simple to implement for this biocompatible and nontoxic probe. Here a time-gated system with ∼10 ns resolution is described, using an intensified CCD camera and pulsed LED or laser excitation sources. The method is demonstrated by tracking the fate of mesoporous silicon nanoparticles containing the tumor-targeting peptide iRGD, administered by retro-orbital injection into live mice. Imaging of such systemically administered nanoparticles in vivo is particularly challenging because of the low concentration of probe in the targeted tissues and relatively high background signals from tissue autofluorescence. Contrast improvements of >100-fold (relative to steady-state imaging) is demonstrated in the targeted tissues.

  9. Luminescent lanthanide complexes for advanced photonic applications

    NASA Astrophysics Data System (ADS)

    Puntus, Lada N.; Sergeeva, Elena V.; Antonov, Dmitrii Y.; Lyssenko, Konstantin A.; Kajzar, Francois

    2010-10-01

    The lanthanide compounds containing unsymmetrical β-diketone with [2.2]paracyclophane moiety in particular the europium complex with three [1-(4-[2.2]paracyclophanyl)]-3-phenylpropane-1,3-dione and 1,10-phenanthroline has been synthesized for the first time. The optical properties of [2.2]paracyclophane-derived ligands (symmetrical β-diketones and their respective N-phenylimines) as well as those of the europium complex were studied by UV-visible and luminescence spectroscopy. The diastereomers (racemic chiral, (R*,R*)- and achiral meso, (R,S)-) of the β-diketones and their respective N-phenylimines exhibit quite identical absorption spectra with intense broad band centered at 360 and 380 nm, respectively. The designed blue-emitting unsymmetrical β-diketone acts as a very efficient sensitizer of the EuIII emission and does so in the near-UV region. The introduction of [2.2]paracyclophane moiety in the β-diketones allows to expand the excitation wavelength of the lanthanide complex up to 500 nm and to obtain the relatively high overall quantum yield for the europium ion.

  10. Luminescent Solar Concentrators in the Algal Industry

    NASA Astrophysics Data System (ADS)

    Hellier, Katie; Corrado, Carley; Carter, Sue; Detweiler, Angela; Bebout, Leslie

    2013-03-01

    Today's industry for renewable energy sources and highly efficient energy management systems is rapidly increasing. Development of increased efficiency Luminescent Solar Concentrators (LSCs) has brought about new applications for commercial interests, including greenhouses for agricultural crops. This project is taking first steps to explore the potential of LSCs to enhance production and reduce costs for algae and cyanobacteria used in biofuels and nutraceuticals. This pilot phase uses LSC filtered light for algal growth trials in greenhouses and laboratory experiments, creating specific wavelength combinations to determine effects of discrete solar light regimes on algal growth and the reduction of heating and water loss in the system. Enhancing the optimal spectra for specific algae will not only increase production, but has the potential to lessen contamination of large scale production due to competition from other algae and bacteria. Providing LSC filtered light will reduce evaporation and heating in regions with limited water supply, while the increased energy output from photovoltaic cells will reduce costs of heating and mixing cultures, thus creating a more efficient and cost effective production system.

  11. Gated Luminescence Imaging of Silicon Nanoparticles

    PubMed Central

    Joo, Jinmyoung; Liu, Xiangyou; Kotamraju, Venkata Ramana; Ruoslahti, Erkki; Nam, Yoonkey; Sailor, Michael J.

    2016-01-01

    The luminescence lifetime of nanocrystalline silicon is typically on the order of microseconds, significantly longer than the nanosecond lifetimes exhibited by fluorescent molecules naturally present in cells and tissues. Time-gated imaging, where the image is acquired at a time after termination of an excitation pulse, allows discrimination of a silicon nanoparticle probe from these endogenous signals. Because of the microsecond time scale for silicon emission, time-gated imaging is relatively simple to implement for this biocompatible and nontoxic probe. Here a time-gated system with ~10 ns resolution is described, using an intensified CCD camera and pulsed LED or laser excitation sources. The method is demonstrated by tracking the fate of mesoporous silicon nanoparticles containing the tumor-targeting peptide iRGD, administered by retro-orbital injection into live mice. Imaging of such systemically administered nanoparticles in vivo is particularly challenging because of the low concentration of probe in the targeted tissues and relatively high background signals from tissue autofluorescence. Contrast improvements of >100-fold (relative to steady-state imaging) is demonstrated in the targeted tissues. PMID:26034817

  12. Grassy Silica Nanoribbons and Strong Blue Luminescence

    NASA Astrophysics Data System (ADS)

    Wang, Shengping; Xie, Shuang; Huang, Guowei; Guo, Hongxuan; Cho, Yujin; Chen, Jun; Fujita, Daisuke; Xu, Mingsheng

    2016-09-01

    Silicon dioxide (SiO2) is one of the key materials in many modern technological applications such as in metal oxide semiconductor transistors, photovoltaic solar cells, pollution removal, and biomedicine. We report the accidental discovery of free-standing grassy silica nanoribbons directly grown on SiO2/Si platform which is commonly used for field-effect transistors fabrication without other precursor. We investigate the formation mechanism of this novel silica nanostructure that has not been previously documented. The silica nanoribbons are flexible and can be manipulated by electron-beam. The silica nanoribbons exhibit strong blue emission at about 467 nm, together with UV and red emissions as investigated by cathodoluminescence technique. The origins of the luminescence are attributed to various defects in the silica nanoribbons; and the intensity change of the blue emission and green emission at about 550 nm is discussed in the frame of the defect density. Our study may lead to rational design of the new silica-based materials for a wide range of applications.

  13. Dynamics of polydots: Soft luminescent polymeric nanoparticles

    DOE PAGES

    Maskey, Sabina; Osti, Naresh C.; Grest, Gary S.; ...

    2016-03-04

    The conformation and dynamics of luminescent polymers collapsed into nanoparticles or polydots were studied using fully atomistic molecular dynamics (MD) simulations, providing a first insight into their internal dynamics. Controlling the conformation and dynamics of confined polymers is essential for realization of the full potential of polydots in nanomedicine and biotechnology. Specifically, the shape and internal dynamics of polydots that consist of highly rigid dialkyl p-phenylene ethynylene (PPE) are probed as a function of temperature. At room temperature, the polydots are spherical without any correlations between the aromatic rings on the PPE backbone. With increasing temperature, they expand and becomemore » slightly aspherical; however, the polymers remain confined. The coherent dynamic structure factor reveals that the internal motion of the polymer backbone is arrested, and the side chains dominate the internal dynamics of the polydots. Lastly, these new soft nanoparticles retain their overall shape and dynamics over an extended temperature range, and their conformation is tunable via their degree of expansion.« less

  14. Grassy Silica Nanoribbons and Strong Blue Luminescence

    PubMed Central

    Wang, Shengping; Xie, Shuang; Huang, Guowei; Guo, Hongxuan; Cho, Yujin; Chen, Jun; Fujita, Daisuke; Xu, Mingsheng

    2016-01-01

    Silicon dioxide (SiO2) is one of the key materials in many modern technological applications such as in metal oxide semiconductor transistors, photovoltaic solar cells, pollution removal, and biomedicine. We report the accidental discovery of free-standing grassy silica nanoribbons directly grown on SiO2/Si platform which is commonly used for field-effect transistors fabrication without other precursor. We investigate the formation mechanism of this novel silica nanostructure that has not been previously documented. The silica nanoribbons are flexible and can be manipulated by electron-beam. The silica nanoribbons exhibit strong blue emission at about 467 nm, together with UV and red emissions as investigated by cathodoluminescence technique. The origins of the luminescence are attributed to various defects in the silica nanoribbons; and the intensity change of the blue emission and green emission at about 550 nm is discussed in the frame of the defect density. Our study may lead to rational design of the new silica-based materials for a wide range of applications. PMID:27666663

  15. Luminescent Silica Nanoparticles for cancer diagnosis

    PubMed Central

    Montalti, Marco; Petrizza, Luca; Rampazzo, Enrico; Zaccheroni, Nelsi; Marchiò, Serena

    2015-01-01

    Fluorescence imaging techniques are becoming essential in preclinical investigations, and the research of suitable tools for in vivo measurements is gaining more and more importance and attention. Nanotechnology entered the field to try to find solutions for many limitation at the state of the art, and luminescent nanoparticles (NPs) are one of the most promising materials proposed for future diagnostic implementation. NPs constitute also a versatile platform that can allow facile multi-functionalization to perform multimodal imaging or theranostic (simultaneous diagnosis and therapy). In this contribution we have focussed our attention only on dye doped silica or silica-based NPs conjugated with targeting moieties to enable specific cancer cells imaging and differentiation, even if also a few non targeted systems have been cited and discussed for completeness. We have summarized common synthetic approaches to these materials and then surveyed the most recent imaging applications of silica-based nanoparticles in cancer. The field of theranostic is so important and stimulating that, even if it is not the central topic of this paper, we have included some significant examples. We have then concluded with short hints on systems already in clinical trials and examples of specific applications in children tumours. This review tries to describe and discuss, through focussed examples, the great potentialities of these materials in the medical field, with the aim to encourage further research to implement applications that are still rare. PMID:23458621

  16. A REVIEW OF APPLICATIONS OF LUMINESCENCE TO MONITORING OF CHEMICAL CONTAMINANTS IN THE ENVIRONMENT

    EPA Science Inventory

    The recent analytical literature on the application of luminescence techniques to the measurement of various classes of environmentally significant chemicals has been reviewed. Luminescent spectroscopy based methods are compared to other current techniques. Also, examples of rece...

  17. FLUORESCENCE CHARACTERIZATION OF IHSS HUMIC SUBSTANCES: TOTAL LUMINESCENCE SPECTRA WITH ABSORBANCE CORRECTION. (R822251)

    EPA Science Inventory

    Total luminescence spectroscopy was applied to the fluorescence characterization of humic substances obtained from the International Humic Substances Society (IHSS). Results show that total luminescence spectra, represented as excitation-emission matrices (EEMs), may be used to d...

  18. Characterising human atherosclerotic carotid plaque tissue composition and morphology using combined spectroscopic and imaging modalities

    PubMed Central

    2015-01-01

    Calcification is a marked pathological component in carotid artery plaque. Studies have suggested that calcification may induce regions of high stress concentrations therefore increasing the potential for rupture. However, the mechanical behaviour of the plaque under the influence of calcification is not fully understood. A method of accurately characterising the calcification coupled with the associated mechanical plaque properties is needed to better understand the impact of calcification on the mechanical behaviour of the plaque during minimally invasive treatments. This study proposes a comparison of biochemical and structural characterisation methods of the calcification in carotid plaque specimens to identify plaque mechanical behaviour. Biochemical analysis, by Fourier Transform Infrared (FTIR) spectroscopy, was used to identify the key components, including calcification, in each plaque sample. However, FTIR has a finite penetration depth which may limit the accuracy of the calcification measurement. Therefore, this FTIR analysis was coupled with the identification of the calcification inclusions located internally in the plaque specimen using micro x-ray computed tomography (μX-CT) which measures the calcification volume fraction (CVF) to total tissue content. The tissue characterisation processes were then applied to the mechanical material plaque properties acquired from experimental circumferential loading of human carotid plaque specimen for comparison of the methods. FTIR characterised the degree of plaque progression by identifying the functional groups associated with lipid, collagen and calcification in each specimen. This identified a negative relationship between stiffness and 'lipid to collagen' and 'calcification to collagen' ratios. However, μX-CT results suggest that CVF measurements relate to overall mechanical stiffness, while peak circumferential strength values may be dependent on specific calcification geometries. This study

  19. User guide for luminescence sampling in archaeological and geological contexts

    USGS Publications Warehouse

    Nelson, Michelle S.; Gray, Harrison J.; Johnson, Jack A.; Rittenour, Tammy M.; Feathers, James K.; Mahan, Shannon

    2015-01-01

    Luminescence dating provides a direct age estimate of the time of last exposure of quartz or feldspar minerals to light or heat and has been successfully applied to deposits, rock surfaces, and fired materials in a number of archaeological and geological settings. Sampling strategies are diverse and can be customized depending on local circumstances, although all sediment samples need to include a light-safe sample and material for dose-rate determination. The accuracy and precision of luminescence dating results are directly related to the type and quality of the material sampled and sample collection methods in the field. Selection of target material for dating should include considerations of adequacy of resetting of the luminescence signal (optical and thermal bleaching), the ability to characterize the radioactive environment surrounding the sample (dose rate), and the lack of evidence for post-depositional mixing (bioturbation in soils and sediment). Sample strategies for collection of samples from sedimentary settings and fired materials are discussed. This paper should be used as a guide for luminescence sampling and is meant to provide essential background information on how to properly collect samples and on the types of materials suitable for luminescence dating.

  20. Zero-reabsorption doped-nanocrystal luminescent solar concentrators.

    PubMed

    Erickson, Christian S; Bradshaw, Liam R; McDowall, Stephen; Gilbertson, John D; Gamelin, Daniel R; Patrick, David L

    2014-04-22

    Optical concentration can lower the cost of solar energy conversion by reducing photovoltaic cell area and increasing photovoltaic efficiency. Luminescent solar concentrators offer an attractive approach to combined spectral and spatial concentration of both specular and diffuse light without tracking, but they have been plagued by luminophore self-absorption losses when employed on practical size scales. Here, we introduce doped semiconductor nanocrystals as a new class of phosphors for use in luminescent solar concentrators. In proof-of-concept experiments, visibly transparent, ultraviolet-selective luminescent solar concentrators have been prepared using colloidal Mn(2+)-doped ZnSe nanocrystals that show no luminescence reabsorption. Optical quantum efficiencies of 37% are measured, yielding a maximum projected energy concentration of ∼6× and flux gain for a-Si photovoltaics of 15.6 in the large-area limit, for the first time bounded not by luminophore self-absorption but by the transparency of the waveguide itself. Future directions in the use of colloidal doped nanocrystals as robust, processable spectrum-shifting phosphors for luminescent solar concentration on the large scales required for practical application of this technology are discussed.

  1. Study of Luminescence Characteristics of Trivalent Terbium in Silicate Glass

    NASA Technical Reports Server (NTRS)

    West, Mike S.; Armagan, Guzin; Winfree, William P.

    1995-01-01

    An important use of silicate glasses doped with terbium oxide (Tb2O3) is their use as fiber optic sensors for high-resolution imaging applications requiring the detection of x-rays (e.g. tomography and radiography). The x-ray radiation is absorbed by the glass, producing electron-hole pairs (excitons). The excitons migrate through the glass matrix and then recombine, emitting characteristic Tb(3+) luminescence in the optical wavelength region. This emission is due to forbidden transitions of 4f electrons and therefore has a long decay time. Long decay time is undesirable when imaging transient events since it results in blurring in time of the images. It has been reported elsewhere that in crystals Tb(3+) ions can act both as luminescence centers and as fluorescence traps. These traps can capture excitons and delay their recombination. This delayed fluorescence is seen as a long lived, secondary component to the luminescence decay curve, or afterglow. Such a secondary decay component to the luminescence decay of Tb(3+) has been observed before in soda glass following pulsed optical excitation. In order to determine the conditions under which afterglow occurs, an understanding of the material's luminescent properties is required.

  2. Occurrence and Expression of Luminescence in Vibrio cholerae▿

    PubMed Central

    Grim, Christopher J.; Taviani, Elisa; Alam, Munirul; Huq, Anwar; Sack, R. Bradley; Colwell, Rita R.

    2008-01-01

    Several species of the genus Vibrio, including Vibrio cholerae, are bioluminescent or contain bioluminescent strains. Previous studies have reported that only 10% of V. cholerae strains are luminescent. Analysis of 224 isolates of non-O1/non-O139 V. cholerae collected from Chesapeake Bay, MD, revealed that 52% (116/224) were luminescent when an improved assay method was employed and 58% (130/224) of isolates harbored the luxA gene. In contrast, 334 non-O1/non-O139 V. cholerae strains isolated from two rural provinces in Bangladesh yielded only 21 (6.3%) luminescent and 35 (10.5%) luxA+ isolates. An additional 270 clinical and environmental isolates of V. cholerae serogroups O1 and O139 were tested, and none were luminescent or harbored luxA. These results indicate that bioluminescence may be a trait specific for non-O1/non-O139 V. cholerae strains that frequently occur in certain environments. Luminescence expression patterns of V. cholerae were also investigated, and isolates could be grouped based on expression level. Several strains with defective expression of the lux operon, including natural K variants, were identified. PMID:18065611

  3. Luminescent Colloidal Semiconductor Nanocrystals Containing Copper: Synthesis, Photophysics, and Applications.

    PubMed

    Knowles, Kathryn E; Hartstein, Kimberly H; Kilburn, Troy B; Marchioro, Arianna; Nelson, Heidi D; Whitham, Patrick J; Gamelin, Daniel R

    2016-09-28

    Copper-doped semiconductors are classic phosphor materials that have been used in a variety of applications for many decades. Colloidal copper-doped semiconductor nanocrystals have recently attracted a great deal of interest because they combine the solution processability and spectral tunability of colloidal nanocrystals with the unique photoluminescence properties of copper-doped semiconductor phosphors. Although ternary and quaternary semiconductors containing copper, such as CuInS2 and Cu2ZnSnS4, have been studied primarily in the context of their photovoltaic applications, when synthesized as colloidal nanocrystals, these materials have photoluminescence properties that are remarkably similar to those of copper-doped semiconductor nanocrystals. This review focuses on the luminescent properties of colloidal copper-doped, copper-based, and related copper-containing semiconductor nanocrystals. Fundamental investigations into the luminescence of copper-containing colloidal nanocrystals are reviewed in the context of the well-established luminescence mechanisms of bulk copper-doped semiconductors and copper(I) molecular coordination complexes. The use of colloidal copper-containing nanocrystals in applications that take advantage of their luminescent properties, such as bioimaging, solid-state lighting, and luminescent solar concentrators, is also discussed.

  4. Water-triggered luminescent "nano-bombs" based on supra-(carbon nanodots).

    PubMed

    Lou, Qing; Qu, Songnan; Jing, Pengtao; Ji, Wenyu; Li, Di; Cao, Junsheng; Zhang, Hong; Liu, Lei; Zhao, Jialong; Shen, Dezhen

    2015-02-25

    Novel luminescent "nano-bombs" based on a self-assembled system of carbon-nanodots, termed supra-CDs, are developed. The luminescence of these luminescent "nano-bombs" depends strongly on water contact; they show weak emission in toluene and decompose in contact with water, resulting in strong photoluminescence. Paper coated with these "nano-bombs" is successfully applied for water-jet printing of luminescence patterns and the mapping of human sweat-pore patterns.

  5. Crystal structures and optical properties of new quaternary strontium europium aluminate luminescent nanoribbons

    DOE PAGES

    Li, Xufan; Budai, John D.; Liu, Feng; ...

    2014-11-12

    We report the synthesis and characterizations of three series of quaternary strontium europium aluminate (Sr-Eu-Al-O; SEAO) luminescent nanoribbons that show blue, green, and yellow luminescence from localized Eu2+ luminescent centers. These three series of SEAO nanoribbons are: blue luminescent, tetragonal Sr1-xEuxAl6O10 (01-xEuxAl2O4 (01-xEuxAl2O4 (0

  6. Ferrous ion induced photon emission as a method to quantify oxidative stress in stored boar spermatozoa.

    PubMed

    Gogol, Piotr; Pieszka, Marek

    2008-01-01

    The aim of the study was to evaluate the effect of semen storage on ferrous ion induced luminescence of boar spermatozoa and to determine the relationship between parameters of this luminescence and lipid peroxidation as measured by malondialdehyde (MDA) contents. Boar semen samples were diluted in Biosolwens extender and stored for 12 days at 15 degrees C. Luminescence and MDA were measured directly after dilution (day 0) and at 6 and 12 days of semen storage. Luminescence was measured at 20 degrees C using a luminometer equipped with a cooled photomultiplier with a spectral response range from 370 to 620 nm. Emission was induced by adding FeSO4 solution (final concentration 0.05 mM). MDA content was measured by the HPLC method. The day of storage had a significant effect on some luminescence parameters and MDA content in spermatozoa. A significant correlation was observed between luminescence parameters and MDA concentration. The results of the study confirm that induced luminescence is strictly related to lipid peroxidation in spermatozoa that occur during boar semen storage. Parameters of luminescence treated as a holistic response of cells to oxidative stress can be useful for monitoring spermatozoa quality during semen preservation.

  7. Modal noise characterisation of a hybrid reformatter

    NASA Astrophysics Data System (ADS)

    Spaleniak, Izabela; MacLachlan, David G.; Gris-Sánchez, Itandehui; Choudhury, Debaditya; Harris, Robert J.; Arriola, Alexander; Allington-Smith, Jeremy R.; Birks, Timothy A.; Thomson, Robert R.

    2016-07-01

    This paper reports on the modal noise characterisation of a hybrid reformatter. The device consists of a multicore-fibre photonic lantern and an ultrafast laser-inscribed slit reformatter. It operates around 1550 nm and supports 92 modes. Photonic lanterns transform a multimode signal into an array of single-mode signals, and thus combine the high coupling efficiency of multimode fibres with the diffraction-limited performance of single-mode fibres. This paper presents experimental measurements of the device point spread function properties under different coupling conditions, and its throughput behaviour at high spectral resolution. The device demonstrates excellent scrambling but its point spread function is not completely stable. Mode field diameter and mode bary-centre position at the device output vary as the multicore fibre is agitated due to the fabrication imperfections.

  8. Physical and functional maps of the luminescence gene cluster in an autoinducer-deficient Vibrio fischeri strain isolated from a squid light organ.

    PubMed Central

    Gray, K M; Greenberg, E P

    1992-01-01

    Vibrio fischeri ES114 is an isolate representing the specific bacterial light organ symbiont of the squid Euprymna scolopes. An interesting feature of this strain of V. fischeri is that it is visibly luminous within the light organ of the squid host but is nonluminous when grown under standard laboratory conditions. Luminescence can be restored in laboratory culture, however, by the addition of autoinducer, a species-specific inducer of the V. fischeri luminescence (lux) genes. Most other isolates of V. fischeri produce autoinducer in sufficient quantities to induce luminescence in laboratory culture. We have cloned an 8.8-kb DNA fragment from V. fischeri ES114 that encodes all of the functions necessary for luminescence in Escherichia coli in the absence of exogenous autoinducer. This DNA contains both of the recognized V. fischeri lux regulatory genes, one of which (luxI) directs E. coli to synthesize autoinducer. The organization of the individual lux genes within this DNA fragment appears to be the same as that in the other strains of V. fischeri studied; the restriction map of the V. fischeri ES114 lux DNA has diverged substantially, however, from the largely conserved maps of V. fischeri MJ1 and ATCC 7744. Although E. coli containing the V. fischeri ES114 lux DNA synthesizes considerable amounts of autoinducer, V. fischeri ES114 synthesizes autoinducer only in small amounts, even when transcription of the lux genes, including luxI, is activated by the addition of exogenous autoinducer. Nonetheless, transconjugants of V. fischeri ES114 that contain multicopy plasmids bearing the ES114 lux genes synthesize sufficient autoinducer to induce luminescence. These results suggest that V. fischeri ES11r does not lack a functional luxl, nor is it deficient in the ability to synthesize metabolic precursors for autoinducer synthesis. PMID:1624432

  9. Neutron flux characterisation of the Pavia TRIGA Mark II research reactor for radiobiological and microdosimetric applications.

    PubMed

    Alloni, D; Prata, M; Salvini, A; Ottolenghi, A

    2015-09-01

    Nowadays the Pavia TRIGA reactor is available for national and international collaboration in various research fields. The TRIGA Mark II nuclear research reactor of the Pavia University offers different in- and out-core neutron irradiation channels, each characterised by different neutron spectra. In the last two years a campaign of measurements and simulations has been performed in order to guarantee a better characterisation of these different fluxes and to meet the demands of irradiations that require precise information on these spectra in particular for radiobiological and microdosimetric studies. Experimental data on neutron fluxes have been collected analysing and measuring the gamma activity induced in thin target foils of different materials irradiated in different TRIGA experimental channels. The data on the induced gamma activities have been processed with the SAND II deconvolution code and finally compared with the spectra obtained with Monte Carlo simulations. The comparison between simulated and measured spectra showed a good agreement allowing a more precise characterisation of the neutron spectra and a validation of the adopted method.

  10. Luminescence properties of Dy3+ doped lanthanum-calcium-silicaborate glass scintillator

    NASA Astrophysics Data System (ADS)

    Park, J. M.; Ha, D. H.; Lee, S. W.; Chanthima, N.; Ruangtaweep, Y.; Kaewkhao, J.

    2016-09-01

    In this research Dy3+-doped lanthanum-calcium-silicaborate glass scintillators, with the formula 25La2O3: 10CaO: 10SiO2: (55-x)B2O3: xDy2O3, were fabricated by using the melt-quenching technique. For the Dy3+ doping concentrations from 0.05 mol% to 0.5 mol% studied the luminescence properties of the Dy3+-doped glass scintillators with various radiation sources, such as X-ray, photo-, laser, and proton. To understand the absorption state, we measured the transmittance spectrum. Furthermore, X-ray, photo- and proton-induced emission spectra were measured to study the transition states of Dy3+-doped glass scintillators. The laser-induced emission spectra were measured at low temperatures in the range from 10 K to 300 K.

  11. Design and synthesis of a terbium(III) complex-based luminescence probe for time-gated luminescence detection of mercury(II) ions.

    PubMed

    Cui, Guanfeng; Ye, Zhiqiang; Zhang, Run; Wang, Guilan; Yuan, Jingli

    2012-01-01

    Time-gated luminescence detection technique using lanthanide complexes as luminescent probes is a useful and highly sensitive method. However, the effective application of this technique is limited by the lack of the target-responsive luminescent lanthanide complexes that can specifically recognize various analytes in aqueous solutions. In this work, a dual-functional ligand that can form a stable complex with Tb(3+) and specifically recognize Hg(2+) ions in aqueous solutions, N,N,N(1),N(1)-{[2,6-bis(3'-aminomethyl-1'-pyrazolyl)-4-[N,N-bis(3″,6″-dithiaoctyl)-aminomethyl]- pyridine]} tetrakis(acetic acid) (BBAPTA), has been designed and synthesized. The luminescence of its Tb(3+) complex is weak, but can be effectively enhanced upon reaction with Hg(2+) ions in aqueous solutions. The luminescence response investigations of BBAPTA-Tb(3+) to various metal ions indicate that the complex has a good luminescence sensing selectivity for Hg(2+) ions, but not for other metal ions. Thus a highly sensitive time-gated luminescence detection method for Hg(2+) ions was developed by using BBAPTA-Tb(3+) as a luminescent probe. The dose-dependent luminescence enhancement of the probe shows a good linearity with a detection limit of 17 nM for Hg(2+) ions. These results demonstrated the efficacy and advantages of the new Tb(3+) complex-based luminescence probe for the sensitive and selective detection of Hg(2+) ions.

  12. Ytterbium (III) Luminescence in m-Methylbenzoic Acid-Containing Compounds.

    PubMed

    Kalinovskaya, I V; Zadorozhnaya, A N

    2015-05-01

    Complex compounds of ytterbium(III) with m-methylbenzoic acid and nitrogen-containing ligands luminescent in near infrared range have been synthesized. Spectral luminescence characteristics of heteroligand compounds of ytterbium(III) have been investigated. It has been established that ytterbium (III) m-methylbenzoate with 1,10-phenanthroline is characterized by the highest luminescence intensity.

  13. Development of a novel europium complex-based luminescent probe for time-gated luminescence imaging of hypochlorous acid in living samples

    NASA Astrophysics Data System (ADS)

    Liu, Xiangli; Guo, Lianying; Song, Bo; Tang, Zhixin; Yuan, Jingli

    2017-03-01

    Luminescent lanthanide complexes are key reagents used in the time-gated luminescence bioassay technique, but functional lanthanide complexes that can act as luminescent probes for specifically responding to analytes are very limited. In this work, we designed and synthesized a novel Eu3+ complex-based luminescence probe for hypochlorous acid (HOCl), NPPTTA-Eu3+, by using terpyridine polyacid-Eu3+, dinitrophenyl, and hydrazine as luminophore, quencher and HOCl-recognizer moieties, respectively. In the absence of HOCl, the probe is non-luminescent due to the strong luminescence quenching of the dinitrophenyl group in the complex. However, upon reaction with HOCl, the dinitrophenyl moiety is rapidly cleaved from the probe, which affords a strongly luminescent Eu3+ complex CPTTA-Eu3+, accompanied by a ∼900-fold luminescence enhancement with a long luminescence lifetime of 1.41 ms. This unique luminescence response of NPPTTA-Eu3+ to HOCl allowed NPPTTA-Eu3+ to be conveniently used as a probe for highly selective and sensitive detection of HOCl under the time-gated luminescence mode. In addition, by loading NPPTTA-Eu3+ into RAW 264.7 macrophage cells and Daphnia magna, the generation of endogenous HOCl in RAW 264.7 cells and the uptake of exogenous HOCl by Daphnia magna were successfully imaged on a true-color time-gated luminescence microscope. The results demonstrated the practical applicability of NPPTTA-Eu3+ as an efficient probe for time-gated luminescence imaging of HOCl in living cells and organisms.

  14. Activatable Multifunctional Persistent Luminescence Nanoparticle/Copper Sulfide Nanoprobe for in Vivo Luminescence Imaging-Guided Photothermal Therapy.

    PubMed

    Chen, Li-Jian; Sun, Shao-Kai; Wang, Yong; Yang, Cheng-Xiong; Wu, Shu-Qi; Yan, Xiu-Ping

    2016-12-07

    Multifunctional nanoprobes that provide diagnosis and treatment features have attracted great interest in precision medicine. Near-infrared (NIR) persistent luminescence nanoparticles (PLNPs) are optimal materials due to no in situ excitation needed, deep tissue penetration, and high signal-to-noise ratio, while activatable optical probes can further enhance signal-to-noise ratio for the signal turn-on nature. Here, we show the design of an activatable multifunctional PLNP/copper sulfide (CuS)-based nanoprobe for luminescence imaging-guided photothermal therapy in vivo. Matrix metalloproteinases (MMPs)-specific peptide substrate (H2N-GPLGVRGC-SH) was used to connect PLNP and CuS to build a MMP activatable system. The nanoprobe not only possesses ultralow-background for in vivo luminescence imaging due to the absence of autofluorescence and optical activatable nature but also offers effective photothermal therapy from CuS nanoparticles. Further bioconjugation of c(RGDyK) enables the nanoprobe for cancer-targeted luminescence imaging-guided photothermal therapy. The good biocompatibility and the multiple functions of highly sensitive tumor-targeting luminescence imaging and effective photothermal therapy make the nanoprobe promising for theranostic application.

  15. Infrared luminescence for real time ionizing radiation detection

    NASA Astrophysics Data System (ADS)

    Veronese, Ivan; Mattia, Cristina De; Fasoli, Mauro; Chiodini, Norberto; Mones, Eleonora; Cantone, Marie Claire; Vedda, Anna

    2014-08-01

    Radio-luminescence (RL) optical fiber sensors enable a remote, punctual, and real time detection of ionizing radiation. However, the employment of such systems for monitoring extended radiation fields with energies above the Cerenkov threshold is still challenging, since a spurious luminescence, namely, the "stem effect," is also generated in the passive fiber portion exposed to radiation. Here, we present experimental measurements on Yb-doped silica optical fibers irradiated with photon fields of different energies and sizes. The results demonstrate that the RL of Yb3+, displaying a sharp emission line at about 975 nm, is free from any spectral superposition with the spurious luminescence. This aspect, in addition with the suitable linearity, reproducibility, and sensitivity properties of the Yb-doped fibers, paves the way to their use in applications where an efficient stem effect removal is required.

  16. Donor characterization in ZnO by thermally stimulated luminescence

    SciTech Connect

    Ji, jianfeng; Boatner, Lynn A; Selim, F. A.

    2014-01-01

    Low temperature thermo-luminescence (TL) was applied to measurements of the ionization energy of donors in ZnO. Three hydrogen-related donors were characterized with ionization energies of 36, 47 and 55 meV - values that are in complete agreement with previous reports. The donor types can be switched by relevant thermal treatments. These measurements also revealed the presence of two distinct sources for the green luminescence in ZnO. This work indicates that TL can be used to measure the donor energies in luminescent semiconductors. This approach can be particularly useful for thin-film investigations when the results of Hall-effect measurements are obscured by contributions from conductive interfaces or substrates.

  17. Applications of quantum dots with upconverting luminescence in bioimaging.

    PubMed

    Chen, Yunyun; Liang, Hong

    2014-06-05

    Quantum dots (QDs) have attracted great attention in recent years due to their promising applications in bioimaging. Compared with traditional ultraviolet excitation of QDs, near-infrared laser (NIR) excitation has many advantages, such as being less harmful, little blinking effects, zero autofluorescence and deep penetration in tissue. Composing QDs with upconverting properties is promising to enable NIR excitation. This article provides a review of QDs with upconverting luminescence and their applications in bioimaging. Based on the mechanisms of luminescence, discussion will be divided into four groups: nanoheterostructures/mixtures of QDs and upconverting nanoparticles, graphene quantum dots, lanthanide-doped QDs, and double QDs. The content includes synthetic routes, upconverting luminescence properties, and their applications in bioimaging.

  18. Luminescent metal nanoclusters: controlled synthesis and functional applications

    PubMed Central

    Sun, Hong-Tao; Sakka, Yoshio

    2014-01-01

    Luminescent metal nanoclusters that consist of only several, to tens of, metal atoms and which possess sizes comparable to the Fermi wavelength of electrons have recently attracted significant attention. This new class of luminescent materials not only provides the missing link between atomic and nanoparticle behaviors in metals but also they present abundant novel information for the development of new applicable material systems to meet urgent needs in many areas (such as ultrasensitive sensors for heavy metals, bioimaging, as well as information technology) mainly because of their attractive characteristics, including ultra-small size, good dispersibility, excellent biocompatibility and photostability. In this review, we summarize recent advances in the controlled synthesis and application of luminescent metal nanoclusters, with a particular emphasis on Pt, Mo, Bi and alloy clusters. We also speculate on their future and discuss potential developments for their use in sensors, bioimaging and energy harvesting and conversion. PMID:27877632

  19. Synthesis, characterization, and green luminescence in ZnO nanocages.

    PubMed

    Snure, Michael; Tiwari, Ashutosh

    2007-02-01

    In this paper, we report the synthesis, characterization and observation of green luminescence in ZnO nanocages. A novel low temperature solution-based technique has been developed for growing highly porous ZnO nano-cages from coarse ZnO precursor powders. Various samples, prepared in this study, were characterized using several different characterization tools such as X-ray diffraction, Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, Raman, Photoluminescence and Optical Transmission Spectroscopy. It has been shown that ZnO nanocages exhibit green luminescence, with PL data showing a broad green peak at 510 nm. The shift and broadening in the luminescence peaks are understood to arise because of the onset of deep level defects in the system.

  20. Luminescence sensitization of Tb(3+)-DNA complexes by Ag().

    PubMed

    Xu, Lijun; Zhou, Lu; Chen, Xing; Shen, Xiaoqiang; Wang, Jine; Zhang, Jianye; Pei, Renjun

    2017-03-03

    Terbium ions (Tb(3+)) with unique photophysical properties have been utilized to develop biosensors with low background and high sensitivity. In this study, the Ag(+)-sensitized luminescence of Tb(3+)-DNA complexes was uncovered. The luminescence of Tb(3+)-DNA complexes could be enhanced by more than 30 times in the presence of Ag(+), when Tb(3+) was bound with poly(G) and poly(T) whereas not with other homopolymers. This research confirmed that the sensitization resulted from the interaction of Ag(+) with certain bases involved in DNA, not just with the reported certain G-quadruplex sequence. The coordination of Ag(+) to guanine and thymine bases was expected to increase their rigidities, form Tb(3+)-DNA-Ag(+) ternary structures, and thus enhance energy transfer from guanine and thymine to Tb(3+). These findings benefit the development of sensitive luminescence probes for various nucleic acids-related targets.

  1. Remarkable luminescence properties of lanthanide complexes with asymmetric dodecahedron structures.

    PubMed

    Miyata, Kohei; Nakagawa, Tetsuya; Kawakami, Ryuhei; Kita, Yuki; Sugimoto, Katsufumi; Nakashima, Takuya; Harada, Takashi; Kawai, Tsuyoshi; Hasegawa, Yasuchika

    2011-01-10

    The distorted coordination structures and luminescence properties of novel lanthanide complexes with oxo-linked bidentate phosphane oxide ligands--4,5-bis(diphenylphosphoryl)-9,9-dimethylxanthene (xantpo), 4,5-bis(di-tert-butylphosphoryl)-9,9-dimethylxanthene (tBu-xantpo), and bis[(2-diphenylphosphoryl)phenyl] ether (dpepo)--and low-vibrational frequency hexafluoroacetylacetonato (hfa) ligands are reported. The lanthanide complexes exhibit characteristic square antiprism and trigonal dodecahedron structures with eight-coordinated oxygen atoms. The luminescence properties of these complexes are characterized by their emission quantum yields, emission lifetimes, and their radiative and nonradiative rate constants. Lanthanide complexes with dodecahedron structures offer markedly high emission quantum yields (Eu: 55-72 %, Sm: 2.4-5.0 % in [D(6)]acetone) due to enhancement of the electric dipole transition and suppression of vibrational relaxation. These remarkable luminescence properties are elucidated in terms of their distorted coordination structures.

  2. Luminescent complexes of terbium ion for molecular recognition of ibuprofen.

    PubMed

    Selivanova, Natalia; Vasilieva, Kristina; Galyametdinov, Yury

    2014-05-01

    The complexation behavior and luminescent properties of terbium (Tb(3+) ) complexes containing bi-dental ligands were studied: nitrogen - 1,10-phenanthroline, and oxygen - trifluoroacetylacetone as well as acetylacetone ligands with ibuprofen (Ibu; a non-steroidal anti-inflammatory drug). Aqueous and aqueous alcohol microheterogeneous solutions were used as media. The effects of solubilization by various micellar solutions, pH and ligand type on luminescent properties of Tb(3+) complexes were investigated. Sensitized luminescence of mixed ligand complex Tb(1,10-phenanthroline)-Ibu and dynamic quenching effect in complex Tb(trifluoroacetylacetone)3 -Ibu allow Ibu determination with the limit of detection 5.3 × 10(-8)  mol/L and 1.26 × 10(-6)  mol/L, respectively.

  3. Luminescence dating of Middle Stone Age deposits at Die Kelders.

    PubMed

    Feathers, J K; Bush, D A

    2000-01-01

    Luminescence dating of sediments has not been used extensively for dating Middle Stone Age deposits in South Africa, despite its potential for contributing to a poorly dated record. Such deposits at Die Kelders cave, on the southern South African coast, consist of narrow bands of occupation debris separated by thicker layers of aeolian sands containing much less evidence of occupation. Homogeneous, aeolian sediments are usually considered ideal for luminescence dating. Here we report luminescence analyses of five samples from these sands that demonstrate sufficient bleaching prior to burial to validate dating and that yield ages of about 60-70 ka, in agreement with other evidence from sedimentology, archaeology and electron spin resonance. Lack of significant differences in the ages suggests the deposits accumulated fairly rapidly during the early part of the Last Glaciation.

  4. Marine plants may polarize remote Fucus eggs via luminescence.

    PubMed

    Jaffe, Lionel F

    2005-01-01

    Fucus zygotes can be polarized by many environmental vectors. These include those created by pieces of all the intertidal marine plants tested. At distances of up to 5-10 mm away from such pieces, Fucus zygotes form their intitial outgrowths or germinate towards them. Earlier papers had inferred that this so-called 'thallus effect' is mediated by diffusing molecules. The present reinvestigation indicates that the thallus effect is exerted by influences that can go right through glass barriers. This indicates action via luminescence. This luminescence may come from bacteria growing in biofilms on the similar surfaces of these otherwise unrelated source plants. Moreover, this directive luminescence is inferred to lie at wavelengths in the red or longer and may take the form of more or less coherent biophotons.

  5. Luminescence from ZnS: Bulk vs nano

    NASA Astrophysics Data System (ADS)

    Mishra, R. K.; Kamal, Satya; Patel, D. K.; Rao, K. Ramachandra; Sudarsan, V.; Vatsa, R. K.

    2015-06-01

    Based on the detailed luminescence studies on bulk and nanoparticles of ZnS, it is inferred that the defect emission due to zinc (VZn) and sulfur (VS) vacancies in ZnS, significantly change in terms of line shape and peak position, when bulk form is converted to nanoparticles. From the XRD studies, this has been explained in terms of difference in the crystalline modifications of ZnS, namely the wurtzite and cubic forms. Copper doping in the sample quenches the luminescence and stabilize the cubic phase. Bright blue electro luminescence (efficiency of around 1.5 %) with CIE coordinates (0.18. 0.11) could be seen from bulk ZnS:Cu sample. Unlike this the nanoparticles did not give any emission due to the quenching of charge carriers/excitons. Lifetime values further supported these inferences.

  6. Infrared luminescence for real time ionizing radiation detection

    SciTech Connect

    Veronese, Ivan Mattia, Cristina De; Cantone, Marie Claire; Fasoli, Mauro; Chiodini, Norberto; Vedda, Anna; Mones, Eleonora

    2014-08-11

    Radio-luminescence (RL) optical fiber sensors enable a remote, punctual, and real time detection of ionizing radiation. However, the employment of such systems for monitoring extended radiation fields with energies above the Cerenkov threshold is still challenging, since a spurious luminescence, namely, the “stem effect,” is also generated in the passive fiber portion exposed to radiation. Here, we present experimental measurements on Yb-doped silica optical fibers irradiated with photon fields of different energies and sizes. The results demonstrate that the RL of Yb{sup 3+}, displaying a sharp emission line at about 975 nm, is free from any spectral superposition with the spurious luminescence. This aspect, in addition with the suitable linearity, reproducibility, and sensitivity properties of the Yb-doped fibers, paves the way to their use in applications where an efficient stem effect removal is required.

  7. Spectral and temporal luminescent properties of Eu(III) in humic substance solutions from different origins

    NASA Astrophysics Data System (ADS)

    Brevet, Julien; Claret, Francis; Reiller, Pascal E.

    2009-10-01

    Although a high heterogeneity of composition is awaited for humic substances, their complexation properties do not seem to greatly depend on their origins. The information on the difference in the structure of these complexes is scarce. To participate in the filling of this lack, a study of the spectral and temporal evolution of the Eu(III) luminescence implied in humic substance (HS) complexes is presented. Seven different extracts, namely Suwannee River fulvic acid (SRFA) and humic acid (SRHA), and Leonardite HA (LHA) from the International Humic Substances Society (USA), humic acid from Gorleben (GohyHA), and from the Kleiner Kranichsee bog (KFA, KHA) from Germany, and purified commercial Aldrich HA (PAHA), were made to contact with Eu(III). Eu(III)-HS time-resolved luminescence properties were compared with aqueous Eu 3+ at pH 5. Using an excitation wavelength of 394 nm, the typical bi-exponential luminescence decay for Eu(III)-HS complexes is common to all the samples. The components τ1 and τ2 are in the same order of magnitude for all the samples, i.e., 40 ≤ τ1 (μs) ≤ 60, and 145 ≤ τ2 (μs) ≤ 190, but significantly different. It is shown that different spectra are obtained from the different groups of samples. Terrestrial extract on the one hand, i.e. LHA/GohyHA, plus PAHA, and purely aquatic extracts on the other hand, i.e., SRFA/SRHA/KFA/KHA, induce inner coherent luminescent properties of Eu(III) within each group. The 5D 0 → 7F 2 transition exhibits the most striking differences. A slight blue shift is observed compared to aqueous Eu 3+ ( λmax = 615.4 nm), and the humic samples share almost the same λmax ≈ 614.5 nm. The main differences between the samples reside in a shoulder around λ ≈ 612.5 nm, modelled by a mixed Gaussian-Lorentzian band around λ ≈ 612 nm. SRFA shows the most intense shoulder with an intensity ratio of I612.5/ I614.7 = 1.1, KFA/KHA/SRHA share almost the same ratio I612.5/ I614.7 = 1.2-1.3, whilst the LHA

  8. Spectral and temporal luminescent properties of Eu(III) in humic substance solutions from different origins.

    PubMed

    Brevet, Julien; Claret, Francis; Reiller, Pascal E

    2009-10-01

    Although a high heterogeneity of composition is awaited for humic substances, their complexation properties do not seem to greatly depend on their origins. The information on the difference in the structure of these complexes is scarce. To participate in the filling of this lack, a study of the spectral and temporal evolution of the Eu(III) luminescence implied in humic substance (HS) complexes is presented. Seven different extracts, namely Suwannee River fulvic acid (SRFA) and humic acid (SRHA), and Leonardite HA (LHA) from the International Humic Substances Society (USA), humic acid from Gorleben (GohyHA), and from the Kleiner Kranichsee bog (KFA, KHA) from Germany, and purified commercial Aldrich HA (PAHA), were made to contact with Eu(III). Eu(III)-HS time-resolved luminescence properties were compared with aqueous Eu(3+) at pH 5. Using an excitation wavelength of 394 nm, the typical bi-exponential luminescence decay for Eu(III)-HS complexes is common to all the samples. The components tau(1) and tau(2) are in the same order of magnitude for all the samples, i.e., 40 induce inner coherent luminescent properties of Eu(III) within each group. The (5)D(0) --> (7)F(2) transition exhibits the most striking differences. A slight blue shift is observed compared to aqueous Eu(3+) (lambda(max) = 615.4 nm), and the humic samples share almost the same lambda(max) approximately 614.5 nm. The main differences between the samples reside in a shoulder around lambda approximately 612.5 nm, modelled by a mixed Gaussian-Lorentzian band around lambda approximately 612 nm. SRFA shows the most intense shoulder with an intensity ratio of I(612.5)/I(614.7) = 1.1, KFA

  9. Visible luminescence from triethanolamine-modified zinc oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Karak, N.; Barik, P.; Kundu, T. K.

    2013-06-01

    We report sol-gel synthesis of ZnO NPs in support of Triethanolamine (TEA) molecules. The particle sizes lie in the range of 23 nm - 43 nm. The blue-shift in absorption spectra for all powders is attributed to the quantum confinement effect. ZnO nanopowder annealed at higher temperature shows an enhanced visible luminescence. In comparison, ZnO specimens having large grain size which are prepared without using TEA do not show any emission with significant intensity. An energy band diagram of nanostructured ZnO specimens explains the luminescence results.

  10. Quartz Luminescence Applied in Palaeoenvironmental Reconstruction of a Dune

    NASA Astrophysics Data System (ADS)

    Przegietka, K. R.; Richter, D.; Chruscinska, A.; Oczkowski, H. L.; Lankauf, K. R.; Szmanda, J.; Luc, M.; Chudziak, W.

    2005-01-01

    Optically stimulated luminescence (OSL) and thermoluminescence (TL) dating were applied for studying the evolution of a dune at the archaeological site of Kaldus (Lower Vistula Valley, Poland), where excavation revealed a settlement sequence. The dating results are supported by investigations of optical bleaching characteristics of the dune quartz. The luminescence studies presented here are a part of a wider interdisciplinary project studying the dynamics of the local geomorphology and its relationship to human activity at the site from prehistoric times until early medieval ages.

  11. [Synthesis, characterization and NIR luminescence properties of erbium organic complexes].

    PubMed

    Wang, Huai-shan; Qian, Guo-dong; Wang, Min-quan; Luo, Yong-shi; Lin, Jiu-ling

    2005-03-01

    Several erbium organic complexes, hydrated erbium binary complexes with acetylacetone (AcAc) or dibenzoylmethane (DBM), erbium ternary complexes derived from 1,10-phenanthroline (Phen) with acetylacetone (AcAc), dibenzoylmethane (DBM) or trifluoroacetylacetone (TFA), were synthesized and identified by elemental analysis. The UV-Vis absorption and FTIR spectra measurements have been employed for all the erbium complexes. Near infrared (NIR) photoluminescence properties, such as luminescence intensity and effective bandwidth, of the erbium complexes were also studied. As a result, the erbium ternary complex with AcAc and Phen exhibits the most excellent luminescence properties among those investigated complexes.

  12. Luminescent properties of fluorophosphate glasses with molecular cadmium selenide clusters

    NASA Astrophysics Data System (ADS)

    Kolobkova, E. V.; Kukushkin, D. S.; Nikonorov, N. V.; Sidorov, A. I.; Shakhverdov, T. A.

    2015-02-01

    It is experimentally shown that, prior to the formation of CdSe quantum dots in fluorophosphate glasses with cadmium and selenium ions in the process of synthesis, subnanosized molecular clusters (CdSe) n are formed, which exhibit luminescence in the visible spectral region upon UV excitation. Heat treatment of the glasses increases the size of molecular clusters and makes their optical properties closer to the optical properties of CdSe semiconductor quantum dots. An increase in the sample temperature from 20 to 250°C leads to reversible thermal quenching of the luminescence.

  13. Luminescence and photoconductivity of high-purity cadmium selenide

    SciTech Connect

    Martynov, V.N.

    1995-10-01

    Slightly off-stoichlometric high-purity cadmium and zinc chalcogenides are used as high-efficiency sensors in various optoelectronic devices. The procedure for preparing high-purity chalcogenides was described elsewhere. Such materials (wurtzite-type structure, sp. gr. C{sup 4}{sub 6v}) exhibit exciton luminescence and the photoconductivity associated with the A-, B-, and C-excitonic series over a wide temperature range. In this work, we studied the luminescence and photoconductivity (PC) of cadmium selenide prepared as described.

  14. Luminescence and charge carrier trapping in YPO4:Bi

    NASA Astrophysics Data System (ADS)

    Awater, Roy H. P.; Niemeijer-Berghuijs, Louise C.; Dorenbos, Pieter

    2017-04-01

    YPO4 doped with Bi3+ and/or Tb3+ samples were prepared in air. X-ray excited luminescence measurements showed emission from isolated Bi3+ and Bi-pairs, and also emission from Bi2+ was observed. Based on the obtained spectroscopic data, the electron binding energies in the ground and excited states of Bi3+ and Bi2+ were placed inside the vacuum referred binding energy (VRBE) scheme, and this was used to explain the luminescence of bismuth doped YPO4. The VRBE scheme and additional thermoluminescence glow curves show that bismuth can act both as electron and as hole trap in YPO4.

  15. Luminescent properties of diamond single crystals of pyramidal shape

    NASA Astrophysics Data System (ADS)

    Alekseev, A. M.; Tuyakova, F. T.; Obraztsova, E. A.; Korostylev, E. V.; Klinov, D. V.; Prusakov, K. A.; Malykhin, S. A.; Ismagilov, R. R.; Obraztsov, A. N.

    2016-11-01

    The luminescence properties of needle-like crystals of diamond, obtained by selective oxidation of textured polycrystalline diamond films, are studied. Diamond films were grown by chemical vapor deposition from a methane-hydrogen mixture activated by a DC discharge. The spectra of photo- and cathodoluminescence and the spatial distribution of the intensity of radiation at different wavelengths are obtained for individual needle-like crystals. Based on the spectral characteristics, conclusions are made about the presence of optically active defects containing nitrogen and silicon impurities in their structure, as well as the significant effect of structural defects on their luminescence spectra.

  16. Optically- and thermally-stimulated luminescences of Ce-doped SiO2 glasses prepared by spark plasma sintering

    NASA Astrophysics Data System (ADS)

    Okada, Go; Kasap, Safa; Yanagida, Takayuki

    2016-11-01

    Rare-earth doped phosphors have been used in many applications including radiation measurements. In the latter applications, the radiation photons are converted to light so that we can indirectly detect the radiation using a conventional photodetector. In this work, we have prepared and characterized a Ce-doped SiO2 glass for dosimeter applications. Unlike conventional techniques such as sol-gel synthesis, the sample was prepared by spark plasma sintering. Although the PL emission seems to be only from the Ce3+ ions in the structure, due to the X-ray induced luminescence, we have also observed optically-stimulated luminescence (OSL), and thermally-stimulated luminescence (TSL), owing to a pair of silylenes and a set of dioxasilirane and silylene in addition to Ce3+. We have measured the detector response vs irradiation dose for both the OSL and TSL. The detector response in both cases is linear over the dose range from at least 1 mGy to 2 Gy. Particularly, the sensitivity of TSL is so high that it should be considered to be a good candidate for practical applications.

  17. Dental depth profilometry using simultaneous frequency-domain infrared photothermal radiometry and laser luminescence for the diagnosis of dental caries

    NASA Astrophysics Data System (ADS)

    Nicolaides, Lena; Garcia, Jose A.; Mandelis, Andreas; Abrams, Stephen H.

    2001-04-01

    Frequency-domain IR photothermal radiometry is introduced as a dynamic dental diagnostic tool and its main features are compared with modulated laser luminescence for quantifying sound and carious enamel or dentin. Dental caries found in the fissures or grooves of teeth is very difficult to diagnose or quantify with the present clinical techniques. Visual examination and dental radiographs do not detect the presence of decay until there has been significant carious destruction of the tooth. A high-spatial-resolution dynamic experimental imaging set-up, which can provide simultaneous measurements of laser-induced frequency-domain IR photothermal radiometric and luminescence signals form defects in teeth, was developed. Following optical absorption of laser photons, the new set-up can monitor simultaneously and independently the non-radiative conversion, and the radiative de-excitation in turbid media such as hard dental tissue. This work is intended to show the complementarity between modulated luminescence and photothermal frequency scans in detecting carious lesions in teeth. A sound extracted molar with a dentin-enamel interface was introduced to examine the depth profilometric abilities of the method. Occlusal surfaces of teeth with potential areas of demineralization or carious destruction in the fissures were examined and compared to the signals produced by the sound enamel establishing the depth profilometric abilities of the method. The significance to clinical dentistry lies in the potential of this technique to detect and monitor early carious lesions in the pits and fissures of teeth.

  18. Bright luminescence from pure DNA-curcumin–based phosphors for bio hybrid light-emitting diodes

    PubMed Central

    Reddy, M. Siva Pratap; Park, Chinho

    2016-01-01

    Recently, significant advances have occurred in the development of phosphors for bio hybrid light-emitting diodes (Bio-HLEDs), which have created brighter, metal-free, rare-earth phosphor-free, eco-friendly, and cost-competitive features for visible light emission. Here, we demonstrate an original approach using bioinspired phosphors in Bio-HLEDs based on natural deoxyribonucleic acid (DNA)-curcumin complexes with cetyltrimethylammonium (CTMA) in bio-crystalline form. The curcumin chromophore was bound to the DNA double helix structure as observed using field emission tunnelling electron microscopy (FE-TEM). Efficient luminescence occurred due to tightly bound curcumin chromophore to DNA duplex. Bio-HLED shows low luminous drop rate of 0.0551 s−1. Moreover, the solid bio-crystals confined the activating bright luminescence with a quantum yield of 62%, thereby overcoming aggregation-induced quenching effect. The results of this study herald the development of commercially viable large-scale hybrid light applications that are environmentally benign. PMID:27572113

  19. Excitation Dependent Phosphorous Property and New Model of the Structured Green Luminescence in ZnO.

    PubMed

    Ye, Honggang; Su, Zhicheng; Tang, Fei; Wang, Mingzheng; Chen, Guangde; Wang, Jian; Xu, Shijie

    2017-02-02

    The copper induced green luminescence (GL) with two sets of fine structures in ZnO crystal has been found for several decades (i.e., R. Dingle, Phys. Rev. Lett. 23, 579 (1969)), but the physical origin of the doublet still remains as an open question up to now. In this paper, we provide new insight into the mechanism of the structured GL band in terms of new experimental findings and theoretical calculations. It is found, for the first time, that the GL signal exhibits persistent afterglow for tens of minutes after the switch-off of below-band-gap excitation light but it cannot occur under above-band-gap excitation. Such a phosphorous property may be interpreted as de-trapping and feeding of electrons from a shallow trapping level via the conduction band to the Cu-related luminescence centers where the Cu(3+) ion is proposed to work as the final state of the GL emission. From first-principles calculation, such a Cu(3+) ion in wurtzite ZnO prefers a high spin 3d(8) state with two non-degenerated half-filled orbitals due to the Jahn-Teller effect, probably leading to the double structures in photoluminescence spectrum. Therefore, this model gives a comprehensively new understanding on the mechanism of the structured GL band in ZnO.

  20. Non-Destructive Micro-Chemical and Micro-Luminescence Characterization of Jadeite.

    PubMed

    Mitrani Viggiano, Alejandro; Ruvalcaba Sil, José Luis; Manrique Ortega, Mayra D; Corregidor Berdasco, Victoria

    2016-12-01

    Jadeite was greatly appreciated by pre-Hispanic cultures in Mesoamerica. Despite its importance, knowledge of its mining sources was lost after the Spanish conquest. In the 1950s the only confirmed jadeite deposits in Mesoamerica were found in the Motagua River Fault (MRF), Guatemala. The aim of this study is to present a methodology that is appropriate for the study of archeological jadeite objects using non-destructive spectroscopic and micro-ion beam analysis techniques. This methodology has been applied to perform mineral, elemental, and luminescence characterization of five jadeite samples from the MRF, with white, lilac, and green colors. Fourier-transformed infrared spectroscopy and X-ray diffraction analysis confirmed the presence of jadeite, albite, and omphacite as the main mineral phases in the samples. Elemental maps using particle-induced X-ray emission (PIXE) with a nuclear microprobe and elemental concentration analysis from individual mineral grains using micro-PIXE coupled with micro-ionoluminescence (IL) allowed the detection of minor feldspar, titanite, and grossular mineral contents. Distinctive features from the mineral, elemental, and luminescence characterization have been found that allow the identification of these five jadeite samples.

  1. Excitation Dependent Phosphorous Property and New Model of the Structured Green Luminescence in ZnO

    PubMed Central

    Ye, Honggang; Su, Zhicheng; Tang, Fei; Wang, Mingzheng; Chen, Guangde; Wang, Jian; Xu, Shijie

    2017-01-01

    The copper induced green luminescence (GL) with two sets of fine structures in ZnO crystal has been found for several decades (i.e., R. Dingle, Phys. Rev. Lett. 23, 579 (1969)), but the physical origin of the doublet still remains as an open question up to now. In this paper, we provide new insight into the mechanism of the structured GL band in terms of new experimental findings and theoretical calculations. It is found, for the first time, that the GL signal exhibits persistent afterglow for tens of minutes after the switch-off of below-band-gap excitation light but it cannot occur under above-band-gap excitation. Such a phosphorous property may be interpreted as de-trapping and feeding of electrons from a shallow trapping level via the conduction band to the Cu-related luminescence centers where the Cu3+ ion is proposed to work as the final state of the GL emission. From first-principles calculation, such a Cu3+ ion in wurtzite ZnO prefers a high spin 3d8 state with two non-degenerated half-filled orbitals due to the Jahn-Teller effect, probably leading to the double structures in photoluminescence spectrum. Therefore, this model gives a comprehensively new understanding on the mechanism of the structured GL band in ZnO. PMID:28150699

  2. Preparation and luminescence properties of ZnO:Ga - polystyrene composite scintillator.

    PubMed

    Burešová, Hana; Procházková, Lenka; Turtos, Rosana Martinez; Jarý, Vítězslav; Mihóková, Eva; Beitlerová, Alena; Pjatkan, Radek; Gundacker, Stefan; Auffray, Etiennette; Lecoq, Paul; Nikl, Martin; Čuba, Václav

    2016-07-11

    Highly luminescent ZnO:Ga-polystyrene composite (ZnO:Ga-PS) with ultrafast subnanosecond decay was prepared by homogeneous embedding the ZnO:Ga scintillating powder into the scintillating organic matrix. The powder was prepared by photo-induced precipitation with subsequent calcination in air and Ar/H2 atmospheres. The composite was subsequently prepared by mixing the ZnO:Ga powder into the polystyrene (10 wt% fraction of ZnO:Ga) and press compacted to the 1 mm thick pellet. Luminescent spectral and kinetic characteristics of ZnO:Ga were preserved. Radioluminescence spectra corresponded purely to the ZnO:Ga scintillating phase and emission of polystyrene at 300-350 nm was absent. These features suggest the presence of non-radiative energy transfer from polystyrene host towards the ZnO:Ga scintillating phase which is confirmed by the measurement of X-ray excited scintillation decay with picosecond time resolution. It shows an ultrafast rise time below the time resolution of the experiment (18 ps) and a single-exponential decay with the decay time around 500 ps.

  3. Bright luminescence from pure DNA-curcumin–based phosphors for bio hybrid light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Reddy, M. Siva Pratap; Park, Chinho

    2016-08-01

    Recently, significant advances have occurred in the development of phosphors for bio hybrid light-emitting diodes (Bio-HLEDs), which have created brighter, metal-free, rare-earth phosphor-free, eco-friendly, and cost-competitive features for visible light emission. Here, we demonstrate an original approach using bioinspired phosphors in Bio-HLEDs based on natural deoxyribonucleic acid (DNA)-curcumin complexes with cetyltrimethylammonium (CTMA) in bio-crystalline form. The curcumin chromophore was bound to the DNA double helix structure as observed using field emission tunnelling electron microscopy (FE-TEM). Efficient luminescence occurred due to tightly bound curcumin chromophore to DNA duplex. Bio-HLED shows low luminous drop rate of 0.0551 s‑1. Moreover, the solid bio-crystals confined the activating bright luminescence with a quantum yield of 62%, thereby overcoming aggregation-induced quenching effect. The results of this study herald the development of commercially viable large-scale hybrid light applications that are environmentally benign.

  4. Enhanced luminescence of Gd2O3:Eu3+ thin-film phosphors by Li doping

    NASA Astrophysics Data System (ADS)

    Yi, Soung-soo; Bae, Jong Seong; Shim, Kyoo Sung; Jeong, Jung Hyun; Park, Jung-Chul; Holloway, P. H.

    2004-01-01

    Gd2O3:Eu3+ and Li-doped Gd2O3:Eu3+ luminescent thin films have been grown on Al2O3 (0001) substrates using pulsed-laser deposition. The films grown under different deposition conditions show different microstructural and luminescent characteristics. Both cubic and monoclinic crystalline structures were observed in Gd2O3:Eu3+ films, but only the cubic crystalline structure was observed for Li-doped Gd2O3:Eu3+ films grown under certain condition. The photoluminescence (PL) brightness data obtained from Li-doped Gd2O3:Eu3+ films indicate that sapphire is a promising substrate for growth of high-quality Li-doped Gd2O3:Eu3+ thin-film red phosphor. In particular, incorporation of Li+ ions into the Gd2O3 lattice can induce a remarkable increase of PL. The highest emission intensity was observed with LiF-doped Gd1.84Li0.08Eu0.08O3, whose brightness was a factor of 2.3 larger than that from Gd2O3:Eu3+ films. This phosphor is promising for applications in flat-panel displays.

  5. Excitation Dependent Phosphorous Property and New Model of the Structured Green Luminescence in ZnO

    NASA Astrophysics Data System (ADS)

    Ye, Honggang; Su, Zhicheng; Tang, Fei; Wang, Mingzheng; Chen, Guangde; Wang, Jian; Xu, Shijie

    2017-02-01

    The copper induced green luminescence (GL) with two sets of fine structures in ZnO crystal has been found for several decades (i.e., R. Dingle, Phys. Rev. Lett. 23, 579 (1969)), but the physical origin of the doublet still remains as an open question up to now. In this paper, we provide new insight into the mechanism of the structured GL band in terms of new experimental findings and theoretical calculations. It is found, for the first time, that the GL signal exhibits persistent afterglow for tens of minutes after the switch-off of below-band-gap excitation light but it cannot occur under above-band-gap excitation. Such a phosphorous property may be interpreted as de-trapping and feeding of electrons from a shallow trapping level via the conduction band to the Cu-related luminescence centers where the Cu3+ ion is proposed to work as the final state of the GL emission. From first-principles calculation, such a Cu3+ ion in wurtzite ZnO prefers a high spin 3d8 state with two non-degenerated half-filled orbitals due to the Jahn-Teller effect, probably leading to the double structures in photoluminescence spectrum. Therefore, this model gives a comprehensively new understanding on the mechanism of the structured GL band in ZnO.

  6. Hyperbranched polyamine assisted synthesis of dual-luminescent gold composite with pH responsive character

    NASA Astrophysics Data System (ADS)

    Yuan, Zhiqin; Du, Yi; He, Yan

    2017-03-01

    We present a facile one-pot, two-step strategy to prepare water-soluble dual-luminescent gold nanodots (AuNDs) and few-atom gold nanocluster composites simultaneously by using high molecular weight and hyperbranched polyethyleneimine (hPEI) as the protection ligand and stabilization agent. It was found that in the presence of hPEI, Au(III) ion can be reduced to a metastable Au(I) charge state in aqueous solution. Subsequently, adding 11-mercaptoundonioic acid induces parallel pathways of restricted Au(I) assembly, leading to the formation of both red-emitting hPEI stabilized AuNDs and blue-emitting hPEI-protected Au8 nanoclusters. The intensity ratio between the blue and red species shows a sensitive and reversible response to the solution pH in the range 2–11 and the dual-luminescent gold composites can act as an effective and reversible pH indicator.

  7. A solid-state dedicated circularly polarized luminescence spectrophotometer: Development and application

    NASA Astrophysics Data System (ADS)

    Harada, Takunori; Hayakawa, Hiroshi; Watanabe, Masayuki; Takamoto, Makoto

    2016-07-01

    A new solid-state dedicated circularly polarized luminescence (CPL) instrument (CPL-200CD) was successfully developed for measuring true CPL spectra for optically anisotropic samples on the basis of the Stokes-Mueller matrix approach. Electric components newly installed in the CPL-200CD include a pulse motor-driven sample rotation holder and a 100 kHz lock-in amplifier to achieve the linearly polarized luminescence measurement, which is essential for obtaining the true CPL signal for optically anisotropic samples. An acquisition approach devised for solid-state CPL analysis reduces the measurement times for a data set by ca. 98% compared with the time required in our previous method. As a result, the developed approach is very effective for samples susceptible to light-induced degradation. The theory and implementation of the method are described, and examples of its application to a CPL sample with macroscopic anisotropies are provided. An important advantage of the developed instrument is its ability to obtain molecular information for both excited and ground states because circular dichroism measurements can be performed by switching the monochromatic light to white light without rearrangement of the sample.

  8. Radiation-induced nonlinear optical response of quartz fibers

    NASA Astrophysics Data System (ADS)

    Plaksin, O. A.

    2006-10-01

    The intensity of radiation-induced luminescence and transient optical losses in KU-1 (Russia) and K-3 (Japan) quartz glass optical tibers irradiated in a fast pulsed fission reactor (a pulse duration of 80 μs and a neutron flux up to 7 × 1016 cm 2 s 2) has been measured in the visible range. The intensity of the fast luminescence component nonlinearly depends on the neutron flux. The luminescence intensity and the transient optical losses depend on the probe light intensity. Suppression of radiation-induced luminescence is observed at wavelengths that are longer or shorter than the probe light wavelength. Light probing leads to an increase in transient optical losses and a more rapid recovery of transparency. A model of two photon fluxes is proposed to analyze the relationship of the effects of suppression of radiation-induced luminescence and the increase in optical losses upon light probing. The effect of suppression of radiation-induced luminescence can be used to control the optical properties of fibers in radiation fields.

  9. Characterising two-pathogen competition in spatially structured environments

    PubMed Central

    Poletto, Chiara; Meloni, Sandro; Van Metre, Ashleigh; Colizza, Vittoria; Moreno, Yamir; Vespignani, Alessandro

    2015-01-01

    Different pathogens spreading in the same host population often generate complex co-circulation dynamics because of the many possible interactions between the pathogens and the host immune system, the host life cycle, and the space structure of the population. Here we focus on the competition between two acute infections and we address the role of host mobility and cross-immunity in shaping possible dominance/co-dominance regimes. Host mobility is modelled as a network of traveling flows connecting nodes of a metapopulation, and the two-pathogen dynamics is simulated with a stochastic mechanistic approach. Results depict a complex scenario where, according to the relation among the epidemiological parameters of the two pathogens, mobility can either be non-influential for the competition dynamics or play a critical role in selecting the dominant pathogen. The characterisation of the parameter space can be explained in terms of the trade-off between pathogen's spreading velocity and its ability to diffuse in a sparse environment. Variations in the cross-immunity level induce a transition between presence and absence of competition. The present study disentangles the role of the relevant biological and ecological factors in the competition dynamics, and provides relevant insights into the spatial ecology of infectious diseases. PMID:25600088

  10. Proteomic techniques for characterisation of mesenchymal stem cell secretome.

    PubMed

    Kupcova Skalnikova, Helena

    2013-12-01

    Mesenchymal stem cells (MSCs) are multipotent cells with a substantial potential in human regenerative medicine due to their ability to migrate to sites of injury, capability to suppress immune response and accessibility in large amount from patient's own bone marrow or fat tissue. It has been increasingly observed that the transplanted MSCs did not necessarily engraft and differentiate at the site of injury but might exert their therapeutic effects through secreted trophic signals. The MSCs secrete a variety of autocrine/paracrine factors, called secretome, that support regenerative processes in the damaged tissue, induce angiogenesis, protect cells from apoptotic cell death and modulate immune system. The cell culture medium conditioned by MSCs or osteogenic, chondrogenic as well as adipogenic precursors derived from MSCs has become a subject of intensive proteomic profiling in the search for and identification of released factors and microvesicles that might be applicable in regenerative medicine. Jointly with the methods for MSC isolation, expansion and differentiation, proteomic analysis of MSC secretome was enabled recently mainly due to the extensive development in protein separation techniques, mass spectrometry, immunological methods and bioinformatics. This review describes proteomic techniques currently applied or prospectively applicable in MSC secretomics, with a particular focus on preparation of the secretome sample, protein/peptide separation, mass spectrometry and protein quantification techniques, analysis of posttranslational modifications, immunological techniques, isolation and characterisation of secreted vesicles and exosomes, analysis of cytokine-encoding mRNAs and bioinformatics.

  11. Microfluidic approaches for epithelial cell layer culture and characterisation

    PubMed Central

    Thuenauer, Roland; Rodriguez-Boulan, Enrique; Römer, Winfried

    2014-01-01

    In higher eukaryotes, epithelial cell layers line most body cavities and form selective barriers that regulate the exchange of solutes between compartments. In order to fulfil these functions, the cells assume a polarised architecture and maintain two distinct plasma membrane domains, the apical domain facing the lumen and the basolateral domain facing other cells and the extracellular matrix. Microfluidic biochips offer the unique opportunity to establish novel in vitro models of epithelia in which the in vivo microenvironment of epithelial cells is precisely reconstituted. In addition, analytical tools to monitor biologically relevant parameters can be directly integrated on-chip. In this review we summarise recently developed biochip designs for culturing epithelial cell layers. Since endothelial cell layers, which line blood vessels, have similar barrier functions and polar organisation as epithelial cell layers, we also discuss biochips for culturing endothelial cell layers. Furthermore, we review approaches to integrate tools to analyse and manipulate epithelia and endothelia in microfluidic biochips, including methods to perform electrical impedance spectroscopy, methods to detect substances undergoing trans-epithelial transport via fluorescence, spectrophotometry, and mass spectrometry, techniques to mechanically stimulate cells via stretching and fluid flow-induced shear stress, and methods to carry out high-resolution imaging of vesicular trafficking with light microscopy. Taken together, this versatile microfluidic toolbox enables novel experimental approaches to characterise epithelial monolayers. PMID:24668405

  12. Characterising two-pathogen competition in spatially structured environments

    NASA Astrophysics Data System (ADS)

    Poletto, Chiara; Meloni, Sandro; van Metre, Ashleigh; Colizza, Vittoria; Moreno, Yamir; Vespignani, Alessandro

    2015-01-01

    Different pathogens spreading in the same host population often generate complex co-circulation dynamics because of the many possible interactions between the pathogens and the host immune system, the host life cycle, and the space structure of the population. Here we focus on the competition between two acute infections and we address the role of host mobility and cross-immunity in shaping possible dominance/co-dominance regimes. Host mobility is modelled as a network of traveling flows connecting nodes of a metapopulation, and the two-pathogen dynamics is simulated with a stochastic mechanistic approach. Results depict a complex scenario where, according to the relation among the epidemiological parameters of the two pathogens, mobility can either be non-influential for the competition dynamics or play a critical role in selecting the dominant pathogen. The characterisation of the parameter space can be explained in terms of the trade-off between pathogen's spreading velocity and its ability to diffuse in a sparse environment. Variations in the cross-immunity level induce a transition between presence and absence of competition. The present study disentangles the role of the relevant biological and ecological factors in the competition dynamics, and provides relevant insights into the spatial ecology of infectious diseases.

  13. A luminescent coordination polymer based on a π-conjugated ligand: Syntheses, structure and luminescent property

    NASA Astrophysics Data System (ADS)

    Li, Dan-Yang; Xie, Hua; Yao, Xiao-Qiang; Ma, Heng-Chang; Lei, Zi-Qiang; Liu, Jia-Cheng

    2017-04-01

    A new cadmium coordination polymer [Cd(DPFE)(adip)0.5(NO3)]n (1) has been synthesized hydrothermally from the self-assembly of the Cd2+ ion with a new π-conjugated rigid ligand DPFE and the adipic acid, where DPFE = 2,7-di(pyridin-4-yl)-9H-fluorene and H2adip = adipic acid. The structure of 1 was full characterized by elemental analysis, FT-IR spectroscopy and single crystal X-ray diffraction. Structural analysis reveals compound 1 is a dinuclear Cd(II) based two-dimensional (4,4) layer and two kinds of strong intramolecular π-π stacking interactions exist between pyridyl rings and benzene rings. In addition, the thermogravimetric analysis and solid-state luminescent properties have also been investigated.

  14. A dual-emitting 4d-4f nanocrystalline metal-organic framework as a self-calibrating luminescent sensor for indoor formaldehyde pollution

    NASA Astrophysics Data System (ADS)

    Hao, Ji-Na; Yan, Bing

    2016-06-01

    A dual-emissive 4d-4f Ag(i)-Eu(iii) functionalized MOF nanocomposite was fabricated and utilized as a self-calibrating luminescent nanoprobe for detecting indoor formaldehyde (FA). The implantation of Ag+ ions can tune the dual-emissive characters of the material. FA can interact with the Ag+ ions and induce opposite luminescence behaviors of the two emitters in the singular molecular material, thus realizing its recognition. This nanoprobe for FA exhibits many merits, such as excellent selectivity, high sensitivity with a detection limit of 51 ppb, fast response, room-temperature testing ability, easy preparation and low cost. This is the first example of a MOF-implicated self-calibrated sensor for indoor FA detection.A dual-emissive 4d-4f Ag(i)-Eu(iii) functionalized MOF nanocomposite was fabricated and utilized as a self-calibrating luminescent nanoprobe for detecting indoor formaldehyde (FA). The implantation of Ag+ ions can tune the dual-emissive characters of the material. FA can interact with the Ag+ ions and induce opposite luminescence behaviors of the two emitters in the singular molecular material, thus realizing its recognition. This nanoprobe for FA exhibits many merits, such as excellent selectivity, high sensitivity with a detection limit of 51 ppb, fast response, room-temperature testing ability, easy preparation and low cost. This is the first example of a MOF-implicated self-calibrated sensor for indoor FA detection. Electronic supplementary information (ESI) available: Experimental procedure, N2 adsorption-desorption isotherms, IR spectra, EDX mappings, ICP data, luminescence data, PXRD patterns, UV-Vis spectra, and XPS spectra. See DOI: 10.1039/c6nr02446g

  15. Photoluminescence properties of green and red luminescence from natural and heat-treated sodalite

    NASA Astrophysics Data System (ADS)

    Kaiheriman, Muyasier; Maimaitinaisier, Alitunguli; Rehiman, Aziguli; Aierken Sidike

    2014-03-01

    The sodalite sample used in this investigation did not exhibit the characteristic orange-yellow luminescence due to the center, because there was no trace of sulfur impurity. The heat-treated samples exhibited green and red luminescence with maximum intensity at 496 and 687 nm, respectively, under 264 nm excitation at room temperature. Their luminescence intensities were extensively dependent on the treatment temperature. The green luminescence efficiency of the sample heat-treated at 900 °C was 6.5 times higher than that of unheated natural sodalite. At 8.5 K, the green luminescence showed a vibronic structure. After heating at 1,300 °C, the crystal structure of sodalite was transformed to NaAlSiO4 (carnegieite), and the intense red luminescence was exhibited in the NaAlSiO4 sample. The peak wavelength of the red luminescence shifted from 687 nm at 300 K to 726 nm at 8.5 K. The luminescence lifetimes of the green and red luminescence at room temperature were 2.1 and 5.1 ms, respectively. It was proposed that the origin of the green luminescence is Mn2+ replacing Na+, and that of the red luminescence is Fe3+ replacing Al3+ in sodalite or NaAlSiO4 (carnegieite).

  16. Monitoring Delamination of Thermal Barrier Coatings by Near-Infrared and Upconversion Luminescence Imaging

    NASA Technical Reports Server (NTRS)

    Eldridge, J. I.; Martin, R. E.; Singh, Jogender; Wolfe, Doug E.

    2008-01-01

    Previous work has demonstrated that TBC delamination can be monitored by incorporating a thin luminescent sublayer that produces greatly increased luminescence intensity from delaminated regions of the TBC. Initial efforts utilized visible-wavelength luminescence from either europium or erbium doped sublayers. This approach exhibited good sensitivity to delamination of electron-beam physical-vapor-deposited (EB-PVD) TBCs, but limited sensitivity to delamination of the more highly scattering plasma-sprayed TBCs due to stronger optical scattering and to interference by luminescence from rare-earth impurities. These difficulties have now been overcome by new strategies employing near-infrared (NIR) and upconversion luminescence imaging. NIR luminescence at 1550 nm was produced in an erbium plus ytterbium co-doped yttria-stabilized zirconia (YSZ) luminescent sublayer using 980-nm excitation. Compared to visible-wavelength luminescence, these NIR emission and excitation wavelengths are much more weakly scattered by the TBC and therefore show much improved depth-probing capabilities. In addition, two-photon upconversion luminescence excitation at 980 nm wavelength produces luminescence emission at 562 nm with near-zero fluorescence background and exceptional contrast for delamination indication. The ability to detect TBC delamination produced by Rockwell indentation and by furnace cycling is demonstrated for both EB-PVD and plasma-sprayed TBCs. The relative strengths of the NIR and upconversion luminescence methods for monitoring TBC delamination are discussed.

  17. Design and synthesis of a new terbium complex-based luminescent probe for time-resolved luminescence sensing of zinc ions.

    PubMed

    Ye, Zhiqiang; Xiao, Yunna; Song, Bo; Yuan, Jingli

    2014-09-01

    Luminescent probes/chemosensors based on lanthanide complexes have shown great potentials in various bioassays due to their unique long-lived luminescence property for eliminating short-lived autofluorescence with time-resolved detection mode. In this work, we designed and synthesized a new dual-chelating ligand {4'-[N,N-bis(2-picolyl)amino]methylene-2,2':6',2'-terpyridine-6,6'-diyl} bis(methylenenitrilo) tetrakis(acetic acid) (BPTTA), and investigated the performance of its Tb(3+) complex (BPTTA-Tb(3+)) for the time-resolved luminescence sensing of Zn(2+) ions in aqueous media. Weakly luminescent BPTTA-Tb(3+) can rapidly react with Zn(2+) ions to display remarkable luminescence enhancement with high sensitivity and selectivity, and such luminescence response can be realized repeatedly. Laudably, the dose-dependent luminescence enhancement shows a good linear response to the concentration of Zn(2+) ions with a detection limit of 4.1 nM. To examine the utility of the new probe for detecting intracellular Zn(2+) ions, the performance of BPTTA-Tb(3+) in the time-resolved luminescence imaging of Zn(2+) ions in living HeLa cells was investigated. The results demonstrated the applicability of BPTTA-Tb(3+) as a probe for the time-resolved luminescence sensing of intracellular Zn(2+) ions.

  18. Luminescent and thermochromic properties of tellurium(IV) halide complexes with cesium

    NASA Astrophysics Data System (ADS)

    Sedakova, T. V.; Mirochnik, A. G.

    2016-02-01

    The spectral-luminescent and thermochromic properties of complex compounds of the composition Cs2TeHal6 (Hal = Cl, Br, I) are studied. The interrelation between the geometric structure and spectral-luminescent properties is studied using the example on complex compounds of tellurium(IV) halides with cesium. The Stokes shift and the luminescence intensity of Te(IV) ions with island octahedral coordination are found to depend on the position of the A band in the luminescence excitation spectra, the diffuse reflection, and the energy of the luminescent 3 P 1 → 1 S 0 transition of the tellurium(IV) ion. The maximum luminescence intensity and the minimum Stokes shift at 77 and 300 K are observed for Cs2TeCl6. The geometrical and electronic factors responsible for luminescence intensification in Te(IV) complexes under study are analyzed.

  19. Luminescence of Eu ion in alumina prepared by plasma electrolytic oxidation

    NASA Astrophysics Data System (ADS)

    Smits, Krisjanis; Millers, Donats; Zolotarjovs, Aleksejs; Drunka, Reinis; Vanks, Martins

    2015-05-01

    Eu ion luminescence in aluminium oxide nanocrystals and layers prepared by plasma electrolytic oxidation (PEO) are investigated in this study. The Eu ion in PEO coatings has intense luminescence allowing such material to be used for preparation of various phosphor materials. In this study, Eu ion doped coatings were prepared with two methods: anodization and pulsed bipolar plasma electrolytic oxidation. Also, for comparative studies, alumina nanocrystals with the same amount of Eu ions were prepared using Sol Gel and molten salts methods. Obtained Eu-doped coatings were studied using luminescence methods. Typical Eu ion luminescence bands were observed, however intensity and spectral distribution differs drastically depending on preparation method and parameters used, therefore the Eu ion luminescence could be used as coating quality luminescent probe. Additionally, the possibility to incorporate the Eu ions in trivalent or divalent state exhibiting bright red and blue luminescence accordingly was demonstrated by using different oxidation parameters. Moreover, comparison measurements between powder samples and coatings were made.

  20. Characterising Cold Weather for the UK mainland

    NASA Astrophysics Data System (ADS)

    Fradley, Kate; Dacre, Helen; Ambaum, Maarten

    2016-04-01

    Excess Winter Mortality is a peak in the population's mortality rate during winter months and is correlated with low outdoor temperatures. Excess Winter Mortality has adverse impacts, including increased demand on health services. The management of resources for such increased demands maybe improved through incorporation of weather forecasting information to advanced warnings. For the UK, prolonged cold periods are associated with easterly advection, and high pressure systems. Characterisation of the synoptic conditions associated with cold periods is important to understand forecast performance. Principal Component Analysis has been used with mean sea level pressure from 35 years of ERA interim reanalysis to capture synoptic variability on a continuous scale. Cold events in the North and South of the UK mainland have been identified as having different synoptic variability using this method. Furthermore extending the Principal Component Analysis to investigate the skill of forecasts has identified systematic under prediction of some cold weather synoptic conditions. Ensemble forecasts are used to quantify the uncertainty associated with these cold weather synoptic conditions. This information maybe be used to improve the value of existing weather warnings.