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Sample records for fluorescent polarization tdx

  1. [THC-carbonic acid determination in serum with fluorescence polarization immunoassay (FPIA, TDX) and GCMS].

    Science.gov (United States)

    Schütz, H W

    1989-01-01

    The Urine-Immuno-Assay (Abbot, TDX) for Cannabis you may also use for the investigation of blood or serum. First the protein is precipitated by Metanol. The solvent is removed by a gentle stream of nitrogen and the solution reconstituted with Phosphat-Buffer. You may handle this solution like urine. Confirmation analysis is made by GCMS after extraction using C-18-extraction tubes and derivation with a proper reagent. Detection limit is about 10 ng/ml. You need only 0.3 ml Serum.

  2. Comparison of the fluorescent polarization (TDx and the enzymatic competitive (EMIT 2000 immune assays for the measurement of cyclosporin A blood concentration Comparação dos imuno-ensaios de fluorescência polarizada (TDx e enzimático competitivo (EMIT 2000 na dosagem da concentração de ciclosporina A no sangue total

    Directory of Open Access Journals (Sweden)

    Elias David-Neto

    2000-12-01

    Full Text Available Evaluation of Cyclosporin A (CyA blood concentration is imperative in solid organ transplantation in order to achieve maximal immunosuppression with the least side effects. We compared the results of whole blood concentrations of CyA in 50 blood samples simultaneously evaluated by the fluorescent polarization immune assay (TDx and the enzymatic competitive immune assay (EMIT 2000. There was a strong correlation between both kits for any range of CyA blood concentration (R=0.99, pA avaliação da concentração sanguínea de ciclosporina A (CyA é necessária em transplantes de órgãos sólidos para obter-se máxima imunosupressão e mínimos efeitos colaterais. Nós comparamos os resultados da concentração de CyA em 50 amostras sanguíneas analisadas pelos métodos dos imuno-ensaios de fluorescência polarizada (TDx e enzimático competitivo (EMIT 2000. Houve uma forte correlação entre ambos métodos para qualquer faixa de concentração de CyA (R=0.99, p<0.001. Os coeficientes de variação intra e interensaio foram menores que 4% para ambos os métodos. O custo para cada análise de CyA foi 50% menor para o EMIT em comparação com o TDx. Concluímos que a metodologia EMIT é tão acurada quanto a de TDx para dosar CyA em amostras sanguíneas. Além disso, a metodologia EMIT é mais prática para ser realizada e mais barata, sendo ainda possível adotá-la para dosagens de CyA em vários horários de um mesmo dia.

  3. Analytical accuracy of determinations of aminoglycoside concentrations by enzyme multiplied immunoassay, fluorescence polarization immunoassay, and radioimmunoassay in the presence of heparin.

    OpenAIRE

    O?Connell, M. E.; Heim, K L; Halstenson, C E; Matzke, G R

    1984-01-01

    The accuracy of gentamicin, netilmicin, and tobramycin concentration determinations by enzyme multiplied immunoassay technique (EMIT; Syva Corp., Palo Alto, Calif.), fluorescence polarization immunoassay (TDx; Abbott Diagnostics, Irving, Tex.), and radioimmunoassay were compared in the presence of 0 to 3,000 USP units of porcine heparin per ml. Gentamicin, netilmicin, and tobramycin concentrations determined by EMIT decreased by 10 and 50% in the presence of 75 and 1,000 USP units/ml, 2 and 5...

  4. Biological applications of confocal fluorescence polarization microscopy

    Science.gov (United States)

    Bigelow, Chad E.

    Fluorescence polarization microscopy is a powerful modality capable of sensing changes in the physical properties and local environment of fluorophores. In this thesis we present new applications for the technique in cancer diagnosis and treatment and explore the limits of the modality in scattering media. We describe modifications to our custom-built confocal fluorescence microscope that enable dual-color imaging, optical fiber-based confocal spectroscopy and fluorescence polarization imaging. Experiments are presented that indicate the performance of the instrument for all three modalities. The limits of confocal fluorescence polarization imaging in scattering media are explored and the microscope parameters necessary for accurate polarization images in this regime are determined. A Monte Carlo routine is developed to model the effect of scattering on images. Included in it are routines to track the polarization state of light using the Mueller-Stokes formalism and a model for fluorescence generation that includes sampling the excitation light polarization ellipse, Brownian motion of excited-state fluorophores in solution, and dipole fluorophore emission. Results from this model are compared to experiments performed on a fluorophore-embedded polymer rod in a turbid medium consisting of polystyrene microspheres in aqueous suspension. We demonstrate the utility of the fluorescence polarization imaging technique for removal of contaminating autofluorescence and for imaging photodynamic therapy drugs in cell monolayers. Images of cells expressing green fluorescent protein are extracted from contaminating fluorescein emission. The distribution of meta-tetrahydroxypheny1chlorin in an EMT6 cell monolayer is also presented. A new technique for imaging enzyme activity is presented that is based on observing changes in the anisotropy of fluorescently-labeled substrates. Proof-of-principle studies are performed in a model system consisting of fluorescently labeled bovine

  5. Comparison of a new serum topiramate immunoassay to fluorescence polarization immunoassay.

    Science.gov (United States)

    Snozek, Christine L H; Rollins, Lisa A; Peterson, Paul W; Langman, Loralie J

    2010-02-01

    Topiramate is a newer anticonvulsant used to treat epilepsy, migraines, bipolar disorder, posttraumatic stress, and other conditions. Serum topiramate concentrations are measured to determine optimal levels, address therapeutic failure or drug-drug interactions, and assess compliance. Two high-throughput assays for serum topiramate measurement were compared: the Seradyn fluorescence polarization immunoassay (FPIA) on an Abbott TDx/FLx instrument and a new immunoassay from ARK Diagnostics performed on an Olympus AU680 automated analyzer. Precision, linearity, limit of quantitation, carryover, spike recovery, and endogenous interferences were found to be acceptable for the ARK assay. These studies were complemented by comparison of 120 patient samples analyzed using both methods. The ARK immunoassay performed comparably to FPIA with minimal difference in serum topiramate concentrations within the therapeutic range (2.0-20 microg/mL). A slight systematic discordance was observed at higher concentrations (greater than 30 microg/mL) with ARK immunoassay results being on average 6% higher than FPIA. Thus, the ARK immunoassay appears to provide acceptable analytical performance and comparability to FPIA; furthermore, the assay is compatible with high-throughput autoanalyzers.

  6. DETERMINATION OF AMINOGLYCOSIDES IN FOOD BY FLUORESCENCE POLARIZATION IMMUNOASSAY

    OpenAIRE

    FARAFONOVA O.V.; Eremin, S. A.; ERMOLAEVA T.N.; VASILIEV S.V.

    2015-01-01

    The methodic for quantitative determination of aminoglycoside antibiotics (gentamicin, kanamycin, streptomycin, amikacin, neomycin) in food by polarization fluorescent immunoassay (FPIA) is developed. The size and structure influence of a fluorescent molecule on a fluorescence polarization degree is analyzed. Affinity constants of antibodies to compounds and tracers were estimated, optimized working concentration of tracers and antibodies that provide the maximum value of analytical signal. M...

  7. Fluorescence polarization imaging for delineating nonmelanoma skin cancers

    Science.gov (United States)

    Yaroslavsky, A. N.; Neel, V.; Anderson, R. R.

    2004-09-01

    We present a method for detecting nonmelanoma skin cancers using exogenous fluorescence polarization. We built an automated system that permits exogenous fluorescence polarization imaging. It includes a tunable linearly polarized monochromatic light source and a CCD camera equipped with a rotating linear polarizer and a filter to reject excitation light. Two fluorophores that are retained in tumors, toluidine blue and methylene blue, are employed. We demonstrate that fluorescence polarization imaging can be used for accurate delineation of nonmelanoma cancers. The results suggest that this optical technique may be suitable for real-time noninvasive demarcation of epithelial cancers.

  8. DETERMINATION OF AMINOGLYCOSIDES IN FOOD BY FLUORESCENCE POLARIZATION IMMUNOASSAY

    Directory of Open Access Journals (Sweden)

    FARAFONOVA O.V.

    2015-01-01

    Full Text Available The methodic for quantitative determination of aminoglycoside antibiotics (gentamicin, kanamycin, streptomycin, amikacin, neomycin in food by polarization fluorescent immunoassay (FPIA is developed. The size and structure influence of a fluorescent molecule on a fluorescence polarization degree is analyzed. Affinity constants of antibodies to compounds and tracers were estimated, optimized working concentration of tracers and antibodies that provide the maximum value of analytical signal. Methods were tested in the antibiotics identification in milk, eggs and chicken.

  9. Fluorescence Polarization Assays in Small Molecule Screening

    Science.gov (United States)

    Lea, Wendy A.; Simeonov, Anton

    2011-01-01

    Importance of the field Fluorescence polarization (FP) is a homogeneous method that allows rapid and quantitative analysis of diverse molecular interactions and enzyme activities. This technique has been widely utilized in clinical and biomedical settings, including the diagnosis of certain diseases and monitoring therapeutic drug levels in body fluids. Recent developments in the field has been symbolized by the facile adoption of FP in high-throughput screening (HTS) and small molecule drug discovery of an increasing range of target classes. Areas covered in this review The article provides a brief overview on the theoretical foundation of FP, followed by updates on recent advancements in its application for various drug target classes, including G-protein coupled receptors (GPCRs), enzymes and protein-protein interactions (PPIs). The strengths and weaknesses of this method, practical considerations in assay design, novel applications, and future directions are also discussed. What the reader will gain The reader will be informed of the most recent advancements and future directions of FP application to small molecule screening. Take home message In addition to its continued utilization in high-throughput screening, FP has expanded into new disease and target areas and has been marked by increased use of labeled small molecule ligands for receptor binding studies. PMID:22328899

  10. SIMULTANEOUS MEASUREMENT OF CIRCULAR DICHROISM AND FLUORESCENCE POLARIZATION ANISOTROPY.

    Energy Technology Data Exchange (ETDEWEB)

    SUTHERLAND,J.C.

    2002-01-19

    Circular dichroism and fluorescence polarization anisotropy are important tools for characterizing biomolecular systems. Both are used extensively in kinetic experiments involving stopped- or continuous flow systems as well as titrations and steady-state spectroscopy. This paper presents the theory for determining circular dichroism and fluorescence polarization anisotropy simultaneously, thus insuring the two parameters are recorded under exactly the same conditions and at exactly the same time in kinetic experiments. The approach to measuring circular dichroism is that used in almost all conventional dichrographs. Two arrangements for measuring fluorescence polarization anisotropy are described. One uses a single fluorescence detector and signal processing with a lock-in amplifier that is similar to the measurement of circular dichroism. The second approach uses classic ''T'' format detection optics, and thus can be used with conventional photon-counting detection electronics. Simple extensions permit the simultaneous measurement of the absorption and excitation intensity corrected fluorescence intensity.

  11. Hybrid fluorescent layer emitting polarized light

    Science.gov (United States)

    Mohammadimasoudi, Mohammad; Beeckman, Jeroen; Hens, Zeger; Neyts, Kristiaan

    2017-07-01

    Semiconductor nanorods have anisotropic absorption and emission properties. In this work a hybrid luminescent layer is produced based on a mixture of CdSe/CdS nanorods dispersed in a liquid crystal that is aligned by an electric field and polymerized by UV illumination. The film emits light with polarization ratio 0.6 (polarization contrast 4:1). Clusters of nanorods in liquid crystal can be avoided by applying an AC electric field with sufficient amplitude. This method can be made compatible with large-scale processing on flexible transparent substrates. Thin polarized light emitters can be used in LCD backlights or solar concentrators to increase the efficiency.

  12. Hybrid fluorescent layer emitting polarized light

    Directory of Open Access Journals (Sweden)

    Mohammad Mohammadimasoudi

    2017-07-01

    Full Text Available Semiconductor nanorods have anisotropic absorption and emission properties. In this work a hybrid luminescent layer is produced based on a mixture of CdSe/CdS nanorods dispersed in a liquid crystal that is aligned by an electric field and polymerized by UV illumination. The film emits light with polarization ratio 0.6 (polarization contrast 4:1. Clusters of nanorods in liquid crystal can be avoided by applying an AC electric field with sufficient amplitude. This method can be made compatible with large-scale processing on flexible transparent substrates. Thin polarized light emitters can be used in LCD backlights or solar concentrators to increase the efficiency.

  13. Polar plot representation of time-resolved fluorescence.

    Science.gov (United States)

    Eichorst, John Paul; Wen Teng, Kai; Clegg, Robert M

    2014-01-01

    Measuring changes in a molecule's fluorescence emission is a common technique to study complex biological systems such as cells and tissues. Although the steady-state fluorescence intensity is frequently used, measuring the average amount of time that a molecule spends in the excited state (the fluorescence lifetime) reveals more detailed information about its local environment. The lifetime is measured in the time domain by detecting directly the decay of fluorescence following excitation by short pulse of light. The lifetime can also be measured in the frequency domain by recording the phase and amplitude of oscillation in the emitted fluorescence of the sample in response to repetitively modulated excitation light. In either the time or frequency domain, the analysis of data to extract lifetimes can be computationally intensive. For example, a variety of iterative fitting algorithms already exist to determine lifetimes from samples that contain multiple fluorescing species. However, recently a method of analysis referred to as the polar plot (or phasor plot) is a graphical tool that projects the time-dependent features of the sample's fluorescence in either the time or frequency domain into the Cartesian plane to characterize the sample's lifetime. The coordinate transformations of the polar plot require only the raw data, and hence, there are no uncertainties from extensive corrections or time-consuming fitting in this analysis. In this chapter, the history and mathematical background of the polar plot will be presented along with examples that highlight how it can be used in both cuvette-based and imaging applications.

  14. Comparative evaluation of the Optimate and TDX analyzers using NCCLS guidelines.

    Science.gov (United States)

    George, H; Fisher, S J; DiMarzio, J M; Horton, C M; Kurtz, S R

    1985-12-01

    A comparative simultaneous evaluation of the Optimate and the TDX analyzers was performed according to guidelines proposed by the National Committee for Clinical Laboratory Standards. Statistically significant (P less than 0.05) better precision was demonstrated for the TDX analyzer with both commercial controls and patient pools. No statistically significant difference was found between the analyzers in terms of linearity, accuracy, and curve stability. Technologists judged the TDX to be superior in ease of start-up and shutdown procedures, loading and unloading, test changeover, time for a stat specimen, and time for an average run. In general, the TDX analyzer required less operator interaction for routine performance, but its consumable expenses were about 50% greater than those for the Optimate analyzer.

  15. Polarized fluorescence correlation spectroscopy of DNA-DAPI complexes

    OpenAIRE

    Barcellona, ML; Gammon, S; Hazlett, T.; Digman, MA; Gratton, E

    2004-01-01

    We discuss the use of fluorescence correlation spectroscopy for the measurement of relatively slow rotations of large macromolecules in solution or attached to other macromolecular structures. We present simulations and experimental results to illustrate the range of rotational correlation times and diffusion times that the technique can analyze. In particular, we examine various methods to analyze the polarization fluctuation data. We have found that by first constructing the polarization fu...

  16. Polarized fluorescence correlation spectroscopy of DNA-DAPI complexes.

    Science.gov (United States)

    Barcellona, Maria Luisa; Gammon, Seth; Hazlett, Theodore; Digman, Michelle A; Gratton, Enrico

    2004-11-01

    We discuss the use of fluorescence correlation spectroscopy for the measurement of relatively slow rotations of large macromolecules in solution or attached to other macromolecular structures. We present simulations and experimental results to illustrate the range of rotational correlation times and diffusion times that the technique can analyze. In particular, we examine various methods to analyze the polarization fluctuation data. We have found that by first constructing the polarization function and then calculating the autocorrelation function, we can obtain the rotational motion of the molecule with very little interference from the lateral diffusion of the macromolecule, as long as the rotational diffusion is significantly faster than the lateral diffusion. Surprisingly, for common fluorophores the autocorrelation of the polarization function is relatively unaffected by the photon statistics. In our instrument, two-photon excitation is used to define a small volume of illumination where a few molecules are present at any instant of time. The measurements of long DNA molecules labeled with the fluorescent probe DAPI show local rotational motions of the polymers in addition to translation motions of the entire polymer. For smaller molecules such as EGFP, the viscosity of the solution must be increased to bring the relaxation due to rotational motion into the measurable range. Overall, our results show that polarized fluorescence correlation spectroscopy can be used to detect fast and slow rotational motion in the time scale from microsecond to second, a range that cannot be easily reached by conventional fluorescence anisotropy decay methods.

  17. Comparative evaluation of digoxin concentrations determined by three assay systems: TDx, IMx and OPUS.

    Science.gov (United States)

    Kagawa, Yoshiyuki; Iwamoto, Takuya; Matsuda, Hiroaki; Mukohara, Rika; Sawada, Jun-ichi; Kojima, Michio

    2004-01-01

    Digoxin concentrations measured by three automated immunoassay systems, i.e. OPUS, TDx and IMx assays, were compared in order to evaluate precision and accuracy performance, and data compatibility. Coefficients of variation for all methods in within-run and between-run precision were less than 10% at weighed-in concentrations of 0.545, 1.090 and 2.180 ng/ml. The accuracy relative to the three weighed-in concentrations ranged from 97% to 123% for all methods. One hundred and three plasma samples from 60 patients receiving digoxin were used to evaluate the data compatibility. Digoxin concentrations measured by the three immunoassay systems correlated well with one another. These results suggest that there are few problems when switching between digoxin assay methods, and that IMx and OPUS are more useful than TDx because they do not require sample pretreatment. The digoxin concentrations of the plasma samples from one patient receiving both digoxin and potassium canrenoate were investigated as a case report. The digoxin concentrations measured by TDx and IMx became higher than those measured by OPUS after starting the combination treatment. In another patient suffering from bilirubinaemia, the digoxin concentrations measured by TDx or IMx were higher than those measured by OPUS. These results suggest that OPUS has a higher specificity for measuring the plasma digoxin concentrations compared with TDx or IMx.

  18. Fluorescence polarization studies of autoionization in CS2

    Science.gov (United States)

    Poliakoff, E. D.; Dehmer, J. L.; Parr, A. C.; Leroi, G. E.

    1987-03-01

    The fluorescence polarization spectrum of CS2(+) produced by photoionization of CS2 (using synchrotron radiation from the NBS SURF-II electron-storage ring) at excitation wavelengths 875-967 A is investigated experimentally, with a focus on autoionization features. The results of polarization measurements for the A2Pi-X2Pi transition are presented in graphs and compared with spectra simulated using the procedure of Poliakoff et al. (1982); qualitative agreement is obtained, but quantitative discrepancies are noted, especially on the low-wavelength side of the resonance. The spectral assignments of Ogawa and Chang (1970) for the autoionizing Rydberg states are confirmed.

  19. Ratiometric fluorescence imaging of cellular polarity: decrease in mitochondrial polarity in cancer cells.

    Science.gov (United States)

    Jiang, Na; Fan, Jiangli; Xu, Feng; Peng, Xiaojun; Mu, Huiying; Wang, Jingyun; Xiong, Xiaoqing

    2015-02-16

    Mitochondrial polarity strongly influences the intracellular transportation of proteins and interactions between biomacromolecules. The first fluorescent probe capable of the ratiometric imaging of mitochondrial polarity is reported. The probe, termed BOB, has two absorption maxima (λabs = 426 and 561 nm) and two emission maxima--a strong green emission (λem = 467 nm) and a weak red emission (642 nm in methanol)--when excited at 405 nm. However, only the green emission is markedly sensitive to polarity changes, thus providing a ratiometric fluorescence response with a good linear relationship in both extensive and narrow ranges of solution polarity. BOB possesses high specificity to mitochondria (Rr =0.96) that is independent of the mitochondrial membrane potential. The mitochondrial polarity in cancer cells was found to be lower than that of normal cells by ratiometric fluorescence imaging with BOB. The difference in mitochondrial polarity might be used to distinguish cancer cells from normal cells.

  20. Cross-reactivity of TDX and OPUS immunoassay systems for serum digoxin determination.

    Science.gov (United States)

    Okazaki, M; Tanigawara, Y; Kita, T; Komada, F; Okumura, K

    1997-12-01

    The properties of the widely used TDX Analyzer and recently developed OPUS Immunoassay System were compared using 403 serum specimens taken from patients who did or did not take digoxin. Of the 210 specimens from patients not treated with digoxin, a false- positive digoxin concentration was detected in 15 specimens (7%) by TDX and in only 2 specimens (1%) by OPUS because of the cross-reactivity with structurally similar drugs. Potassium canrenoate, digitoxin, deslanoside, and methyldigoxin exhibited marked concentration-dependent cross-reactivity in the TDX assay method, whereas deslanoside and methyldigoxin only showed cross-reactivity with the antibody used in the OPUS method. Although a poor correlation was observed between these two methods for the determination of 193 samples from patients treated with digoxin, the correlation was remarkably improved (r = 0.914) and the slope approximated unity when excluded the data from patients who were treated concurrently with the cross-reactive compounds. In routine TDM of digoxin, the authors experienced two cases in which cross-reactivity of the assay system caused a clinical problem. Concurrent administration of intravenous canrenoate apparently interfered with the digoxin assay by TDX, but this problem was solved by using the OPUS system. The authors found OPUS more useful for monitoring serum digoxin concentrations in patients because of its superior specificity.

  1. Studies on the metabolism and toxicological detection of the amphetamine-like anorectic mefenorex in human urine by gas chromatography-mass spectrometry and fluorescence polarization immunoassay.

    Science.gov (United States)

    Kraemer, T; Vernaleken, I; Maurer, H H

    1997-11-21

    Studies on the metabolism and on the toxicological analysis of mefenorex [R,S-N-(3-chloropropyl)-alpha-methylphenethylamine, MF] using gas chromatography-mass spectrometry (GC-MS) and fluorescence polarization immunoassay (FPIA) are described. The metabolites were identified in urine samples of volunteers by GC-MS. Besides MF, thirteen metabolites including amphetamine (AM) could be identified and three partially overlapping metabolic pathways could be postulated. For GC-MS detection, the systematic toxicological analysis procedure including acid hydrolysis, extraction at pH 8-9 and acetylation was suitable (detection limits 50 ng/ml for MF and 100 ng/ml for AM). Excretion studies showed, that only AM but neither MF nor its specific metabolites were detectable between 32 and 68 h after ingestion of 80 mg of MF. Therefore, misinterpretation can occur. The Abbott TDx FPIA amphetamine/methamphetamine II gave positive results up to 68 h. All the positive immunoassay results could be confirmed by the described GC-MS procedure.

  2. Studies on the metabolism and toxicological detection of the amphetamine-like anorectic fenproporex in human urine by gas chromatography-mass spectrometry and fluorescence polarization immunoassay.

    Science.gov (United States)

    Kraemer, T; Theis, G A; Weber, A A; Maurer, H H

    2000-01-28

    Studies on the metabolism and the toxicological analysis of fenproporex (R,S-3-[(1-phenyl-2-propyl)-amino]-propionitrile, FP) using GC-MS and fluorescence polarization immunoassay are described. The metabolites were identified in urine samples of volunteers by GC-MS after cleavage of conjugates, extraction and acetylation. Besides unchanged FP, fourteen metabolites, including amphetamine, could be identified. Two partially overlapping metabolic pathways could be postulated: ring degradation by one- and two-fold aromatic hydroxylation followed by methylation and side chain degradation by N-dealkylation to amphetamine (AM). A minor pathway leads via beta-hydroxylation of AM to norephedrine. For GC-MS detection, the systematic toxicological analysis procedure including acid hydrolysis, extraction at pH 8-9 and acetylation was suitable (detection limits 50 ng/ml for FP and 100 ng/ml for AM). Excretion studies showed, that only AM but neither FP nor its specific metabolites were detectable 30-60 h after ingestion of 20 mg of FP. Therefore, misinterpretation can occur. The Abbott TDx FPIA amphetamine/methamphetamine II gave positive results up to 58 h. All the positive immunoassay results could be confirmed by the described GC-MS procedure.

  3. Fluorescence polarization immunoassay for salinomycin based on monoclonal antibodies

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A fluorescence polarization immunoassay(FPIA) for the determination of salinomycin(SAL) was developed by using anti-SAL monoclonal antibodies(mAb).Fluorescein labeled SAL(tracer) was synthesized by the N-hydroxysuccinimide active ester method and purified using thin layer chromatography(TLC).The developed FPIA for SAL had a dynamic range from 0.60 to 2193 ng/mL with an IC50 value of 33.2 ng/mL and a detection limit(LOD) of 0.08 ng/mL.No significant cross-reactivities were observed with other drugs but 67.6% with narasin.

  4. Polarization properties of fluorescent BSA protected Au25 nanoclusters

    Science.gov (United States)

    Raut, Sangram; Chib, Rahul; Rich, Ryan; Shumilov, Dmytro; Gryczynski, Zygmunt; Gryczynski, Ignacy

    2013-03-01

    BSA protected gold nanoclusters (Au25) are attracting a great deal of attention due to their unique spectroscopic properties and possible use in biophysical applications. Although there are reports on synthetic strategies, spectroscopy and applications, little is known about their polarization behavior. In this study, we synthesized the BSA protected Au25 nanoclusters and studied their steady state and time resolved fluorescence properties including polarization behavior in different solvents: glycerol, propylene glycol and water. We demonstrated that the nanocluster absorption spectrum can be separated from the extinction spectrum by subtraction of Rayleigh scattering. The nanocluster absorption spectrum is well approximated by three Gaussian components. By a comparison of the emissions from BSA Au25 clusters and rhodamine B in water, we estimated the quantum yield of nanoclusters to be higher than 0.06. The fluorescence lifetime of BSA Au25 clusters is long and heterogeneous with an average value of 1.84 μs. In glycerol at -20 °C the anisotropy is high, reaching a value of 0.35. However, the excitation anisotropy strongly depends on the excitation wavelengths indicating a significant overlap of the different transition moments. The anisotropy decay in water reveals a correlation time below 0.2 μs. In propylene glycol the measured correlation time is longer and the initial anisotropy depends on the excitation wavelength. BSA Au25 clusters, due to long lifetime and high polarization, can potentially be used in studying large macromolecules such as protein complexes with large molecular weight.BSA protected gold nanoclusters (Au25) are attracting a great deal of attention due to their unique spectroscopic properties and possible use in biophysical applications. Although there are reports on synthetic strategies, spectroscopy and applications, little is known about their polarization behavior. In this study, we synthesized the BSA protected Au25 nanoclusters and

  5. Analysis of Septin Reorganization at Cytokinesis Using Polarized Fluorescence Microscopy

    Directory of Open Access Journals (Sweden)

    Molly McQuilken

    2017-05-01

    Full Text Available Septins are conserved filament-forming proteins that act in diverse cellular processes. They closely associate with membranes and, in some systems, components of the cytoskeleton. It is not well understood how filaments assemble into higher-order structures in vivo or how they are remodeled throughout the cell cycle. In the budding yeast S. cerevisiae, septins are found through most of the cell cycle in an hourglass organization at the mother-bud neck until cytokinesis when the collar splits into two rings that disassemble prior to the next cell cycle. Experiments using polarized fluorescence microscopy have suggested that septins are arranged in ordered, paired filaments in the hourglass and undergo a coordinated 90° reorientation during splitting at cytokinesis. This apparent reorganization could be due to two orthogonal populations of filaments disassembling and reassembling or being preferentially retained at cytokinesis. In support of this idea, we report a decrease in septin concentration at the mother-bud neck during cytokinesis consistent with other reports and the timing of the decrease depends on known septin regulators including the Gin4 kinase. We took a candidate-based approach to examine what factors control reorientation during splitting and used polarized fluorescence microscopy to screen mutant yeast strains deficient in septin interacting proteins. Using this method, we have linked known septin regulators to different aspects of the assembly, stability, and reorganization of septin assemblies. The data support that ring splitting requires Gin4 activity and an anillin-like protein Bud4, and normal accumulation of septins at the ring requires phosphorylation of Shs1. We found distinct regulatory requirements for septin organization in the hourglass compared to split rings. We propose that septin subpopulations can vary in their localization and assembly/disassembly behavior in a cell-cycle dependent manner at cytokinesis.

  6. Influence of trehalose 6,6'-diester (TDX) chain length on the physicochemical and immunopotentiating properties of DDA/TDX liposomes

    DEFF Research Database (Denmark)

    Kallerup, Rie Selchau; Madsen, Cecilie Maria; Schiøth, Mikkel Lohmann;

    2015-01-01

    Linking physicochemical characterization to functional properties is crucial for defining critical quality attributes during development of subunit vaccines toward optimal safety and efficacy profiles. We investigated how the trehalose 6,6'-diester (TDX) chain length influenced the physicochemical......, immunization of mice with the recombinant tuberculosis fusion antigen Ag85B-ESAT-6-Rv2660c (H56) and the physicochemically most optimal formulations (DDA/TDB, DDA/TDS and DDA/TDP) induced comparable T-cell responses. In conclusion, of the investigated TDB analogues, incorporation of 11mol% TDS or TDP into DDA...... liposomes resulted in an adjuvant system with the most favorable physicochemical properties and an immunological profile comparable to that of DDA/TDB....

  7. Polarization contrast in fluorescence scanning near-field optical microscopy in reflection

    NARCIS (Netherlands)

    Jalocha, A.; Hulst, van N.F.

    1995-01-01

    Polarization contrast is presented in fluorescence images of a Langmuir-Blodgett monolayer obtained with a scanning near-field optical microscope operated in reflection. A tapered optical fiber is used both to excite and to collect the fluorescence. The lateral resolution in the reflection fluoresce

  8. Field trial of the brucellosis fluorescence polarization assay.

    Science.gov (United States)

    Nielsen, K; Gall, D; Bermudez, R; Renteria, T; Moreno, F; Corral, A; Monroy, O; Monge, F; Smith, P; Widdison, J; Mardrueno, M; Calderon, N; Guerrero, R; Tinoco, R; Osuna, J; Kelly, W

    2002-01-01

    Fluorescence polarization assay (FPA) is a homogeneous technique which was applied to the serological diagnosis of bovine brucellosis. Because of its simplicity and because it may be performed very rapidly, it was an ideal test to adapt to field use. The FPA was used to test cattle on six dairy farms in Baja California, Mexico. Anticoagulated blood, serum, and milk were collected from each animal. The anticoagulated blood was tested immediately on the farm while serum and milk were tested subsequently in the laboratory. Cattle on one farm (n = 140) were thought not to be infected with Brucella abortus and the other farms were thought to have high prevalence of the infection. The whole blood FPA (FPA(bld)) did not detect antibody in any of the cattle on the first premise. This finding was confirmed using a number of other serological tests, including the buffered antigen plate agglutination test, the complement fixation test, the indirect and competitive enzyme immunoassays, and the FPA using serum and milk. Cattle on the other premises (n = 1122) were tested in a similar fashion. The sensitivity of the FPA(bld), relative to the serum FPA (considered the definitive test), was 99.1% and the relative specificity of the FPA(bld) was 99.6%. These results compared favourably with those obtained using the other serological tests.

  9. Diagnosis of bovine brucellosis using a homogeneous fluorescence polarization assay.

    Science.gov (United States)

    Nielsen, K; Gall, D; Lin, M; Massangill, C; Samartino, L; Perez, B; Coats, M; Hennager, S; Dajer, A; Nicoletti, P; Thomas, F

    1998-12-11

    To evaluate the fluorescence polarization assay (FPA) for the serological diagnosis of bovine brucellosis, 118 sera from cattle which were culture positive for Brucella abortus, 1751 sera from cattle from premises containing cattle infected with B. abortus, 1222 sera from cattle vaccinated with B. abortus strain 19 and 1199 sera from cattle with no evidence of brucellosis were tested in Argentina, Chile, Mexico and in the American states of Iowa, Missouri and Texas. Initial determination of serological positivity and negativity was based upon reactivity in currently used serological tests, consisting of a rapid screening test, the rose-bengal or the buffered plate antigen tests, followed by a second serological test, the complement fixation test. Sensitivity of the FPA (sera from culture positive animals) ranged from 87.5% to 100%. Serological positivity of cattle from infected premises ranged from 65.5% to 99.0% while the % negative cattle in herds without evidence of brucellosis was between 94.9 and 100%. Of B. abortus strain 19 vaccinated cattle which were positive in at least one in-use serological tests, 88.2% were negative in the FPA. In contrast, previous Canadian studies, sensitivity values were 99.0% and 100% and the specificity in both cases was 100%. This discrepancy was probably due to the use of less well characterized sera in the current study.

  10. Improving the fluorescence polarization method to evaluate the orientation of fluorescent systems adsorbed in ordered layered materials

    Energy Technology Data Exchange (ETDEWEB)

    Salleres, Sandra [Departamento de Quimica Fisica, Universidad del Pais Vasco UPV/EHU, Apartado 644, 48080 Bilbao (Spain); Arbeloa, Fernando Lopez, E-mail: fernando.lopezarbeloa@ehu.e [Departamento de Quimica Fisica, Universidad del Pais Vasco UPV/EHU, Apartado 644, 48080 Bilbao (Spain); Martinez, Virginia Martinez; Arbeloa, Teresa; Lopez Arbeloa, Inigo [Departamento de Quimica Fisica, Universidad del Pais Vasco UPV/EHU, Apartado 644, 48080 Bilbao (Spain)

    2009-11-15

    The fluorescence polarization method, recently developed for the evaluation of the preferential orientation of fluorescent dyes adsorbed in layered materials [F. Lopez Arbeloa, V. Martinez Martinez, J. Photochem. Photobiol. A: Chem. 181 (2006) 44], is readapted to improve its application. Fluorescence polarization was previously obtained by recording the emission intensity for two orthogonal orientations of the emission polarizer (i.e., the horizontal and vertical polarized light) after excitation with vertical or horizontal polarized light. In the method proposed in this work, samples are excited with unpolarized light, reducing the polarization effect of the excitation light scattering at those emission wavelengths close to the excitation wavelength. Moreover, the present method decreases the effect of the orientation of other non-fluorescent species present in the system, which are active in the excitation process. Consequently, the new method is more simple, precise and sensitive. It is applied to evaluate the orientation of rhodamine 6G dye adsorbed in ordered laponite clay films with low and moderated dye loadings.

  11. Effects of external fields, dimension and polarization on the resonance fluorescence of quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Vaseghi, B., E-mail: vaseghi@mail.yu.ac.ir; Razavi, S.M.

    2017-02-01

    In this paper simultaneous effects of external electric and magnetic fields, dimension and polarization on the resonance fluorescence spectrum and photon statistics of a spherical quantum dot with parabolic confinement are investigated. With special attention to the optical scattering processes resonance fluorescence spectrum and second-order correlation function are calculated and plotted for different external parameters. Our results show the occurrence of resonance fluorescence similar to atomic systems and considerable effects of external fields, quantum confinement and light polarization on the resonance fluorescence spectrum and second-order correlation function in the quantum dot systems. The existence of Mollow triplets and photon antibunching are strongly depend on these external agents.

  12. Effects of external fields, dimension and polarization on the resonance fluorescence of quantum dots

    Science.gov (United States)

    Vaseghi, B.; Razavi, S. M.

    2017-02-01

    In this paper simultaneous effects of external electric and magnetic fields, dimension and polarization on the resonance fluorescence spectrum and photon statistics of a spherical quantum dot with parabolic confinement are investigated. With special attention to the optical scattering processes resonance fluorescence spectrum and second-order correlation function are calculated and plotted for different external parameters. Our results show the occurrence of resonance fluorescence similar to atomic systems and considerable effects of external fields, quantum confinement and light polarization on the resonance fluorescence spectrum and second-order correlation function in the quantum dot systems. The existence of Mollow triplets and photon antibunching are strongly depend on these external agents.

  13. Fluorescence polarization competition assay: the range of resolvable inhibitor potency is limited by the affinity of the fluorescent ligand.

    Science.gov (United States)

    Huang, Xinyi

    2003-02-01

    For the development of fluorescence polarization (FP) competition assays, there is a widespread belief that tight-binding fluorescent ligands should be avoided to identify inhibitors of low or intermediate potency in the screening of small-molecule compound libraries. It is demonstrated herein that this statement is a misconception; in fact, the higher the affinity of the fluorescent ligand, the wider the range of inhibitor potency that can be resolved. An approximate estimate for the low end of inhibitor K(i) values that can be resolved is the K(d) value of the fluorescent ligand. Because FP competition assays are typically conducted under nonstoichiometric titration conditions, it is suggested that a fluorescent ligand of highest affinity that also has an adequate quantum yield to satisfy such conditions be selected.

  14. Probing Field-Induced Tissue Polarization Using Transillumination Fluorescent Imaging

    OpenAIRE

    Caldwell, Bryan J; Wellner, Marcel; Mitrea, Bogdan G.; PERTSOV, ARKADY M.; Zemlin, Christian W.

    2010-01-01

    Despite major successes of biophysical theories in predicting the effects of electrical shocks within the heart, recent optical mapping studies have revealed two major discrepancies between theory and experiment: 1), the presence of negative bulk polarization recorded during strong shocks; and 2), the unexpectedly small surface polarization under shock electrodes. There is little consensus as to whether these differences result from deficiencies of experimental techniques, artifacts of tissue...

  15. Fluorescence anisotropy excitation by polarization-shaped laser pulses after transmission through a kagome fiber

    Science.gov (United States)

    Otto, J.; Patas, A.; Althoff, J.; Lindinger, A.

    2016-08-01

    We report improved fluorescence contrast between dyes by two-photon excitation with polarization-shaped laser pulses after transmission through a kagome fiber utilizing the anisotropy of the dye molecules. Particularly phase- and polarization-tailored pulse shapes are employed for two-photon excited fluorescence of dyes in a liquid environment at the distal end of the kagome fiber. The distortions due to the optical fiber properties are precompensated in order to receive predefined polarization-shaped laser pulses after the kagome fiber. This enables to optimally excite one dye in one polarization direction and simultaneously the other dye in the other polarization direction. The presented method has a high potential for endoscopic applications due to the unique properties of kagome fibers for guiding ultrashort laser pulses.

  16. Spectrally resolved fluorescence lifetime imaging of Nile red for measurements of intracellular polarity

    Science.gov (United States)

    Levitt, James A.; Chung, Pei-Hua; Suhling, Klaus

    2015-09-01

    Spectrally resolved confocal microscopy and fluorescence lifetime imaging have been used to measure the polarity of lipid-rich regions in living HeLa cells stained with Nile red. The emission peak from the solvatochromic dye in lipid droplets is at a shorter wavelength than other, more polar, stained internal membranes, and this is indicative of a low polarity environment. We estimate that the dielectric constant, ɛ, is around 5 in lipid droplets and 25<ɛ<40 in other lipid-rich regions. Our spectrally resolved fluorescence lifetime imaging microscopy (FLIM) data show that intracellular Nile red exhibits complex, multiexponential fluorescence decays due to emission from a short lifetime locally excited state and a longer lifetime intramolecular charge transfer state. We measure an increase in the average fluorescence lifetime of the dye with increasing emission wavelength, as shown using phasor plots of the FLIM data. We also show using these phasor plots that the shortest lifetime decay components arise from lipid droplets. Thus, fluorescence lifetime is a viable contrast parameter for distinguishing lipid droplets from other stained lipid-rich regions. Finally, we discuss the FLIM of Nile red as a method for simultaneously mapping both polarity and relative viscosity based on fluorescence lifetime measurements.

  17. A rapid and sensitive method to detect mycobacterium tuberculosis DNA by fluorescence polarization

    Institute of Scientific and Technical Information of China (English)

    白玉杰; 赵锦荣; 薛丽; 刘爱翔; 张文红; 郭晏海; 闫小君

    2004-01-01

    Objective: To develop a new high sensitivity, rapid and simple mycobacterium tuberculosis DNA detection method using fluorescence polarization technology. Methods: In our asymmetric PCR protocol, 100 times mole of TB-R primer was added than in the usual symmetric PCR to get enough single strands PCR product. The probe TB-5'-TAMRA and PCR products were mixed in a tube and incubate for 5 - 15 min at 46 C. The polarization (mp) was measured using victor2Multilabel Plate Reader. Results: Asymmetric and symmetric PCR products were analyzed by the FP method. Asymmetric PCR products are detected more sensitively than symmetric ones. The polarization values of probe associated with asymmetric products were much higher than with symmetric products. Conclusion: This fluorescence polarization assay in conjunction with asymmetric PCR is a powerful and widely applicable method for the rapid and sensitive detection of micro-organisms in clinical laboratories.

  18. Characteristic spectral features of the polarized fluorescence of human breast cancer in the wavelet domain

    CERN Document Server

    Gharekhan, Anita H; Gupta, Sharad; Panigrahi, Prasanta K; Pradhan, Asima

    2012-01-01

    Wavelet transform of polarized fluorescence spectra of human breast tissues is found to localize spectral features that can reliably differentiate normal and malignant tissue types. The intensity differences of parallel and perpendicularly polarized fluorescence spectra are subjected to investigation, since the same is relatively free of the diffusive background. A number of parameters, capturing spectral variations and subtle changes in the diseased tissues in the visible wavelength regime, are clearly identifiable in the wavelet domain. These manifest both in the average low pass and high frequency high pass wavelet coefficients.

  19. Coexistence of Probe Conformations in Lipid Phases—A Polarized Fluorescence Microspectroscopy Study

    OpenAIRE

    Urbančič, Iztok; Ljubetič, Ajasja; Arsov, Zoran; Štrancar, Janez

    2013-01-01

    Several well-established fluorescence methods depend on environment-sensitive probes that report about molecular properties of their local environment. For reliable interpretation of experiments, careful characterization of probes’ behavior is required. In this study, bleaching-corrected polarized fluorescence microspectroscopy with nanometer spectral peak position resolution was applied to characterize conformations of two alkyl chain-labeled 7-nitro-2-1,3-benzoxadiazol-4-yl phospholipids in...

  20. Measurement of Three-Dimensional Dipole Orientation of a Single Fluorescent Nanoemitter by Emission Polarization Analysis

    OpenAIRE

    Lethiec, Clotilde; Laverdant, Julien; Vallon, Henri; Javaux, Clémentine; Dubertret, Benoît; Frigerio, Jean-Marc; Schwob, Catherine; Coolen, Laurent; Maître, Agnès

    2014-01-01

    International audience; We demonstrate theoretically and experimentally that the three-dimensional orientation of a single fluorescent nanoemitter can be determined by polarization analysis of the emitted light (while excitation polarization analysis provides only the in-plane orientation). The determination of the emitter orientation by polarimetry requires a theoretical description, including the objective numerical aperture, the 1D or 2D nature of the emitting dipole, and the environment c...

  1. Fluorescence anisotropy (polarization): from drug screening to precision medicine

    Science.gov (United States)

    Zhang, Hairong; Wu, Qian; Berezin, Mikhail Y.

    2016-01-01

    Introduction Fluorescence anisotropy (FA) is one of the major established methods accepted by industry and regulatory agencies for understanding the mechanisms of drug action and selecting drug candidates utilizing a high-throughput format. Areas covered This review covers the basics of FA and complementary methods, such as fluorescence lifetime anisotropy and their roles in the drug discovery process. The authors highlight the factors affecting FA readouts, fluorophore selection, and instrumentation. Furthermore, the authors describe the recent development of a successful, commercially valuable FA assay for Long QT syndrome drug toxicity to illustrate the role that FA can play in the early stages of drug discovery. Expert opinion Despite the success in drug discovery, the FA-based technique experiences competitive pressure from other homogeneous assays. That being said, FA is an established yet rapidly developing technique, recognized by academic institutions, the pharmaceutical industry, and regulatory agencies across the globe. The technical problems encountered in working with small molecules in homogeneous assays are largely solved, and new challenges come from more complex biological molecules and nanoparticles. With that, FA will remain one of the major work-horse techniques leading to precision (personalized) medicine. PMID:26289575

  2. Temperature dependence and polarization of fluorescence from Photosystem I in the cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Wittmershaus, B P; Woolf, V M; Vermaas, W F

    1992-02-01

    To determine the fluorescence properties of cyanobacterial Photosystem I (PS I) in relatively intact systems, fluorescence emission from 20 to 295 K and polarization at 77 K have been measured from phycobilisomes-less thylakoids of Synechocystis sp. PCC 6803 and a mutant strain lacking Photosystem II (PS II). At 295 K, the fluorescence maxima are 686 nm in the wild type from PS I and PS II and at 688 nm from PS I in the mutant. This emission is characteristic of bulk antenna chlorophylls (Chls). The 690-nm fluorescence component of PS I is temperature independent. For wild-type and mutant, 725-nm fluorescence increases by a factor of at least 40 from 295 to 20 K. We model this temperature dependence assuming a small number of Chls within PS I, emitting at 725 nm, with an energy level below that of the reaction center, P700. Their excitation transfer rate to P700 decreases with decreasing temperature increasing the yield of 725-nm fluorescence.Fluorescence excitation spectra of polarized emission from low-energy Chls were measured at 77 and 295 K on the mutant lacking PS II. At excitation wavelengths longer than 715 nm, 760-nm emission is highly polarized indicating either direct excitation of the emitting Chls with no participation in excitation transfer or total alignment of the chromophores. Fluorescence at 760 nm is unpolarized for excitation wavelengths shorter than 690 nm, inferring excitation transfer between Chls before 760-nm fluorescence occurs.Our measurements illustrate that: 1) a single group of low-energy Chls (F725) of the core-like PS I complex in cyanobacteria shows a strongly temperature-dependent fluorescence and, when directly excited, nearly complete fluorescence polarization, 2) these properties are not the result of detergent-induced artifacts as we are examining intact PS I within the thylakoid membrane of S. 6803, and 3) the activation energy for excitation transfer from F725 Chls to P700 is less than that of F735 Chls in green plants; F725

  3. New applications of fluorescence polarization for enzyme assays and in genomics

    Science.gov (United States)

    Nikiforov, Theo; Coffin, Jill; Jeong, Sang; Simeonov, Anton; Bi, Xiahui

    2001-05-01

    We have developed new, fluorescence polarization-based approaches for performing enzyme assays in homogeneous solutions and for detecting the hybridization of peptide nucleic acids to DNA targets. In the first method, fluorescein-labeled peptides serving as protein kinase sustrates are thiophosphorylated in the presence of the ATP analog ATPγS. A sulfer-reactive biotin derivative is then added to the mixture and allowed to react with the thiophosphorylated peptide. The formation of a fluorescein-labeled, biotinylated product can be detected by measuring the fluorescence polarization signal of fluorescein upon addition of streptavidin. In the second method, fluorescein-labeled peptides are subjected to enzymatic phosphorylation, desphosphorlation, or proteollytic cleavage by protein kinases, phosphatases, and proteases. The differential binding of the enzymatic substrates and products to cationic polymers such as polyaraginine can be conveniently measured by fluorescence polarization. Finally, we have discovered that the process of hybridization of peptide nucleic acid probes (PNAs) to their target DNA molecules can be followed by measuring the fluorescence polarization of a fluorophore attached to the PNA probes. These measurements can be done either in the presence or absence of polylysine in solution. Examples of the application of this method for single nucleotide polymorphism (SNP) typing are presented.

  4. Putting the pieces together: contribution of fluorescence polarization assays to small-molecule lead optimization

    Science.gov (United States)

    Keating, Susan M.; Marsters, Jim; Beresini, Maureen; Ladner, Carmen; Zioncheck, Kim; Clark, Kevin; Arellano, Fred; Bodary, Sarah

    2000-04-01

    Fluorescence polarization assays with both purified receptor and intact cells have been developed to assess potency and selectivity of antagonists of the interaction of the lymphocyte receptor, LFA-1, and its endothelial ligand, ICAM-1. Fluorescein isothiocyanate conjugated small molecule probes were optimized for use in binding assay with LFA-1 and a closely related receptor, MAC-1. In the assays, the antagonists compete with the fluorescent probe for binding to the receptor. This enables the determination of IC50 and consequently Ki values of the antagonists for each of the receptors. Routine use of polarization assay with tranfected cells, in addition to purified receptors, has become feasible with the availability of sensitive plate readers that are able to detect 1 nM fluorescent probe in 15 (mu) l sample volumes with good signal to noise. These measurements aid in the iterative synthesis of more potent and selective compounds.

  5. Femtosecond dynamics of the S2 and S1 fluorescence of ionic styryl dyes in polar solvents

    NARCIS (Netherlands)

    H. Wang; W. Rettig; A.I. Tolmachev; M. Glasbeek

    2004-01-01

    Femtosecond fluorescence upconversion and picosecond time-correlated single-photon counting fluorescence experiments for bridged and unbridged ionic styryl dye compounds in polar solvents are reported. The measured fluorescence transients reveal S2 S1 internal conversion (IC) with a typical time of

  6. Coexistence of probe conformations in lipid phases-a polarized fluorescence microspectroscopy study.

    Science.gov (United States)

    Urbančič, Iztok; Ljubetič, Ajasja; Arsov, Zoran; Strancar, Janez

    2013-08-20

    Several well-established fluorescence methods depend on environment-sensitive probes that report about molecular properties of their local environment. For reliable interpretation of experiments, careful characterization of probes' behavior is required. In this study, bleaching-corrected polarized fluorescence microspectroscopy with nanometer spectral peak position resolution was applied to characterize conformations of two alkyl chain-labeled 7-nitro-2-1,3-benzoxadiazol-4-yl phospholipids in three model membranes, representing the three main lipid phases. The combination of polarized and spectral detection revealed two main probe conformations with their preferential fluorophore dipole orientations roughly parallel and perpendicular to membrane normal. Their peak positions were separated by 2-6 nm because of different local polarities and depended on lipid environment. The relative populations of conformations, estimated by a numerical model, indicated a specific sensitivity of the two probes to molecular packing with cholesterol. The coexistence of probe conformations could be further exploited to investigate membrane organization below microscopy spatial resolution, such as lipid rafts. With the addition of polarized excitation or detection to any environment-sensitive fluorescence imaging technique, the conformational analysis can be directly applied to explore local membrane complexity.

  7. High-Contrast Fluorescence Microscopy for a Biomolecular Analysis Based on Polarization Techniques Using an Optical Interference Mirror Slide

    Directory of Open Access Journals (Sweden)

    Mitsuru Yasuda

    2014-12-01

    Full Text Available Fluorescence microscopy with an improved contrast for fluorescence images is developed using an optical interference mirror (OIM slide, which can enhance the fluorescence from a fluorophore as a result of the double interference of the excitation light and emission light. To improve the contrast of a fluorescence image using an OIM slide, a linearly-polarized excitation light was employed, and the fluorescence emission polarized perpendicular to the polarization of the excitation light was detected. The image contrast with this optical system was improved 110-fold for rhodamine B spotted on the OIM, in comparison with a glass slide using a general fluorescence microscopy optical system. Moreover, a 24-fold improvement of the image contrast was achieved for the detection of Cy3-labeled streptavidin bound to immobilize biotin.

  8. ARCHITECT与TDx测定环孢素A血药浓度相关性研究%Correlation between Whole Blood Cyclosporine Concentration Assayed by ARCHITECT and TDx

    Institute of Scientific and Technical Information of China (English)

    李朋梅; 刘晓; 张镭; 赵莉; 张相林

    2011-01-01

    目的 研究ARCHITECT与TDx两种方法测定环孢素A(CsA)血药浓度结果相关性.方法 利用ARCHITECT和TDx两种方法同时测定CsA血药浓度,以TDx测定值为X,ARCHITECT测定值为Y,进行线性回归,评价其相关性.结果 ARCHITECT测定值均比TDx低,pTDx/pARCHITECT为(1.29±0.22),两种方法的线性相关性较好,回归方程为Y=-26.26+0·993 9X(n=65,r=0.9665).结论 ARCHITECT测定CsA血药浓度结果较TDx偏低,两种方法相关性好,可以进行方法间切换.%OBJECTIVE To evaluate the correlation between the whole blood cyclosporine A (CsA) concentrations by ARCHITECT and TDx monoclonal assay. METHODS A total of 65 samples from renal allograft recipients were determined by ARCHITECT and TDx monoclonal analyzer simultaneously. Regression analyses were performed (ARCHITECT results as dependant, TDx as inde-pendant variable) for the evaluation of correlation. RESULTS ARCHITECT results were all lower than those from TDx. Pm/ Parchttect was (1.29 ±0.22). There existed good correlation with least-squares equation Y= -26.26 +0.993 9X(n =65,r =0.966 5). CONCLUSION There is good correlation between ARCHITECT and TDx assay results. ARCHITECT has achieved a definite improvement in specificity for the parent drug compared with TDx. It can be used for routine monitoring of CsA

  9. Fluorescence polarization of amniotic fluid to assess fetal lung maturity in high risk pregnancies

    Directory of Open Access Journals (Sweden)

    Tadeu Gantus Simão Stefano

    2006-06-01

    Full Text Available Objective: To assess the accuracy, sensitivity, specificity, and thepositive and negative predictive values of amniotic fluidfluorescence polarization for neonatal respiratory distresssyndrome in high risk pregnancies. Methods: A prospectivedescriptive study of 54 patients with high risk pregnancies. Fetallung maturity was assessed using amniotic fluid florescencepolarization obtained by amniocentesis up to 72 hours beforedelivery. Respiratory distress syndrome, stratified by gestationalage at birth, was the primary outcome analyzed. Amniotic fluidfluorescence polarization values equal to or over 50 mg/g (indicatingfetal lung maturity were considered as negative results. Results:The mean gestational age at birth was 35 weeks (SD 2.0.Respiratory distress syndrome was seen in 14 newborns(24%. Amniotic fluid fluorescence polarization had high sensitivity(86% and specificity (81%, with 14% false-negative and 19% falsepositiveresults. The positive predictive value was 60% and thenegative predictive value was 94%. The area under the ROC curveindicated the 50 mg/g albumin/surfactant ratio as the best cutoffpoint (85% sensitivity and 81% specificity. Conclusion: A negativevalue in amniotic fluid fluorescence polarization (results equal toor over 50 mg/g confirms lung maturity which translates into avery low risk of a newborn developing respiratory distresssyndrome in high risk pregnancies.

  10. Polarization-dependent responses of fluorescent indicators partitioned into myelinated axons

    Science.gov (United States)

    Micu, Ileana; Brideau, Craig; Stys, Peter K.

    2012-02-01

    Myelination, i.e. the wrapping of axons in multiple layers of lipid-rich membrane, is a unique phenomenon in the nervous systems of both vertebrates and invertebrates, that greatly increases the speed and efficiency of signal transmission. In turn, disruption of axo-myelinic integrity underlies disability in numerous clinical disorders. The dependence of myelin physiology on nanometric organization of its lamellae makes it difficult to accurately study this structure in the living state. We expected that fluorescent probes might become highly oriented when partitioned into the myelin sheath, and in turn, this anisotropy could be interrogated by controlling the polarization state of the exciting laser field used for 2-photon excited fluorescence (TPEF). Live ex vivo myelinated rodent axons were labeled with a series of lipohilic and hydrophilic fluorescenct probes, and TPEF images acquired while laser polarization was varied at the sample over a broad range of ellipticities and orientations of the major angle [see Brideau, Micu & Stys, abstract this meeting]. We found that most probes exhibited strong dependence on both the major angle of polarization, and perhaps more surprisingly, on ellipticity as well. Lipophilic vs. hydrophilic probes exhibited distinctly different behavior. We propose that polarization-dependent TPEF microscopy represents a powerful tool for probing the nanostructural architecture of both myelin and axonal cytoskeleton in a domain far below the resolution limit of visible light microscopy. By selecting probes with different sizes and physicochemical properties, distinct aspects of cellular nanoarchitecture can be accurately interrogated in real-time in living tissue.

  11. Calculating the contribution of different binding modes to Quinacrine - DNA complex formation from polarized fluorescence data

    CERN Document Server

    Voloshin, Igor; Karachevtsev, Victor; Zozulya, Victor

    2013-01-01

    Binding of acridine derivative quinacrine (QA) to chicken erythrocyte DNA was studied by methods of absorption and polarized fluorescent spectroscopy. Measurements were carried out in aqueous buffered solutions (pH 6.9) of different dye concentrations (QA concentration range from $10^{-6}$ till $10^{-4}$ M) and ionic strengths ($Na^{+}$ concentration rang from $10^{-3}$ till 0.15 M) in a wide range of phosphate-to-dye molar ratios ($P/D$). It is established that the minimum of fluorescent titration curve plotted as relative fluorescence intensity $vs$ $P/D$ is conditioned by the competition between the two types of QA binding to DNA which posses by different emission parameters: (i) intercalative one dominating under high $P/D$ values, and (ii) outside electrostatic binding dominating under low $P/D$ values, which is accompanied by the formation of non-fluorescent dye associates on the DNA backbone. Absorption and fluorescent characteristics of complexes formed were determined. The method of calculation of di...

  12. The spectral properties of (--epigallocatechin 3-O-gallate (EGCG fluorescence in different solvents: dependence on solvent polarity.

    Directory of Open Access Journals (Sweden)

    Vladislav Snitsarev

    Full Text Available (--Epigallocatechin 3-O-gallate (EGCG a molecule found in green tea and known for a plethora of bioactive properties is an inhibitor of heat shock protein 90 (HSP90, a protein of interest as a target for cancer and neuroprotection. Determination of the spectral properties of EGCG fluorescence in environments similar to those of binding sites found in proteins provides an important tool to directly study protein-EGCG interactions. The goal of this study is to examine the spectral properties of EGCG fluorescence in an aqueous buffer (AB at pH=7.0, acetonitrile (AN (a polar aprotic solvent, dimethylsulfoxide (DMSO (a polar aprotic solvent, and ethanol (EtOH (a polar protic solvent. We demonstrate that EGCG is a highly fluorescent molecule when excited at approximately 275 nm with emission maxima between 350 and 400 nm depending on solvent. Another smaller excitation peak was found when EGCG is excited at approximately 235 nm with maximum emission between 340 and 400 nm. We found that the fluorescence intensity (FI of EGCG in AB at pH=7.0 is significantly quenched, and that it is about 85 times higher in an aprotic solvent DMSO. The Stokes shifts of EGCG fluorescence were determined by solvent polarity. In addition, while the emission maxima of EGCG fluorescence in AB, DMSO, and EtOH follow the Lippert-Mataga equation, its fluorescence in AN points to non-specific solvent effects on EGCG fluorescence. We conclude that significant solvent-dependent changes in both fluorescence intensity and fluorescence emission shifts can be effectively used to distinguish EGCG in aqueous solutions from EGCG in environments of different polarity, and, thus, can be used to study specific EGCG binding to protein binding sites where the environment is often different from aqueous in terms of polarity.

  13. Lymphocyte fluorescence polarization measurements with the cellscan system: application to the SCM cancer test.

    Science.gov (United States)

    Deutsch, M; Ron, I; Weinreb, A; Tirosh, R; Chaitchik, S

    1996-02-01

    The SCM (Structuredness of Cytoplasmic Matrix) cancer test, a procedure based on detection of differences in lymphocyte activation between individuals with and without cancer, has remained controversial with inconsistent results reported by different authors. As originally described, the test includes two technically demanding steps, the first a lymphocyte separation procedure and the second a series of fluorescence polarization measurements. The Cellscan, a high-precision static cytometer system has been configured to perform the SCM test. The apparatus facilitates the polarization measurements and can analyze cells separated using simpler procedures than were originally described. Using methods and diagnostic criteria adapted for the Cellscan system, the SCM test correctly classified > 90% of patients with cancer and > 90% of individuals without cancer.

  14. Diagnosis of human breast cancer through wavelet transform of polarized fluorescence

    CERN Document Server

    Biswal, N C; Pradhan, A; Panigrahi, P K; Biswal, Nrusingh C.; Gupta, Sharad; Pradhan, Asima; Panigrahi, Prasanta K.

    2004-01-01

    Wavelet transform of polarized fluorescence spectroscopic data of human breast tissues is found to reliably differentiate normal and malignant tissue types and isolate characteristic biochemical signatures of cancerous tissues, which can possibly be used for diagnostic purpose. A number of parameters capturing spectral variations and subtle changes in the diseased tissues in the visible wavelength regime are clearly identifiable in the wavelet domain. These investigations, corroborated with tissue phantoms, indicate that the observed differences between malignant tumor and normal samples are primarily ascribable to the changes in concentration of porphyrin and density of cellular organelles present in tumors.

  15. Fluorescence Intensity and Polarization from Photodissociated H2, D2 and HD

    Science.gov (United States)

    Machacek, J. R.; Andrianarijaona, V. M.; Furst, J. E.; Gay, T. J.; Kilcoyne, A. L. D.; Landers, A. L.; McLaughlin, K. W.

    2009-05-01

    We have measured the intensity and linear polarization of Hα (n=3->n=2) 656.3 nm fluorescence resulting from H and D atoms created by photodissociation of H2, D2 and HD using linearly-polarized photons with energies ranging from 16.5 to 17.6 eV. Between the threshold for atomic n=3 production at 16.6 eV and the n=4 production threshold at 17.3 eV, the relative cross section and polarization data are free from cascade contributions due to higher-lying atomic states. The photon beam energy width used for this work was 3 meV. Comparison of relative intensities to previous measurements [1] show marked differences. However, the polarization is in qualitative agreement. [1] H. Frohlich et al., Z. Phys. D 34, 119 (1995). Support provided by the NSF (Grant PHY-0653379), DOE (LBNL/ALS) and ANSTO (Access to Major Research Facilities Programme).

  16. Identification of adiponectin receptor agonist utilizing a fluorescence polarization based high throughput assay.

    Directory of Open Access Journals (Sweden)

    Yiyi Sun

    Full Text Available Adiponectin, the adipose-derived hormone, plays an important role in the suppression of metabolic disorders that can result in type 2 diabetes, obesity, and atherosclerosis. It has been shown that up-regulation of adiponectin or adiponectin receptor has a number of therapeutic benefits. Given that it is hard to convert the full size adiponectin protein into a viable drug, adiponectin receptor agonists could be designed or identified using high-throughput screening. Here, we report on the development of a two-step screening process to identify adiponectin agonists. First step, we developed a high throughput screening assay based on fluorescence polarization to identify adiponectin ligands. The fluorescence polarization assay reported here could be adapted to screening against larger small molecular compound libraries. A natural product library containing 10,000 compounds was screened and 9 hits were selected for validation. These compounds have been taken for the second-step in vitro tests to confirm their agonistic activity. The most active adiponectin receptor 1 agonists are matairesinol, arctiin, (--arctigenin and gramine. The most active adiponectin receptor 2 agonists are parthenolide, taxifoliol, deoxyschizandrin, and syringin. These compounds may be useful drug candidates for hypoadiponectin related diseases.

  17. Automatic analyzer for highly polar carboxylic acids based on fluorescence derivatization-liquid chromatography.

    Science.gov (United States)

    Todoroki, Kenichiro; Nakano, Tatsuki; Ishii, Yasuhiro; Goto, Kanoko; Tomita, Ryoko; Fujioka, Toshihiro; Min, Jun Zhe; Inoue, Koichi; Toyo'oka, Toshimasa

    2015-03-01

    A sensitive, versatile, and reproducible automatic analyzer for highly polar carboxylic acids based on a fluorescence derivatization-liquid chromatography (LC) method was developed. In this method, carboxylic acids were automatically and fluorescently derivatized with 4-(N,N-dimethylaminosulfonyl)-7-piperazino-2,1,3-benzoxadiazole (DBD-PZ) in the presence of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride by adopting a pretreatment program installed in an LC autosampler. All of the DBD-PZ-carboxylic acid derivatives were separated on the ODS column within 30 min by gradient elution. The peak of DBD-PZ did not interfere with the separation and the quantification of all the acids with the exception of lactic acid. From the LC-MS/MS analysis, we confirmed that lactic acid was converted to an oxytriazinyl derivative, which was further modified with a dimethoxy triazine group of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM). We detected this oxytriazinyl derivative to quantify lactic acid. The detection limits (signal-to-noise ratio = 3) for the examined acids ranged from 0.19 to 1.1 µm, which correspond to 95-550 fmol per injection. The intra- and inter-day precisions of typical, highly polar carboxylic acids were all carboxylic acids in various samples, which included fruit juices, red wine and media from cultured tumor cells.

  18. Identification of Adiponectin Receptor Agonist Utilizing a Fluorescence Polarization Based High Throughput Assay

    Science.gov (United States)

    Sun, Yiyi; Zang, Zhihe; Zhong, Ling; Wu, Min; Su, Qing; Gao, Xiurong; Zan, Wang; Lin, Dong; Zhao, Yan; Zhang, Zhonglin

    2013-01-01

    Adiponectin, the adipose-derived hormone, plays an important role in the suppression of metabolic disorders that can result in type 2 diabetes, obesity, and atherosclerosis. It has been shown that up-regulation of adiponectin or adiponectin receptor has a number of therapeutic benefits. Given that it is hard to convert the full size adiponectin protein into a viable drug, adiponectin receptor agonists could be designed or identified using high-throughput screening. Here, we report on the development of a two-step screening process to identify adiponectin agonists. First step, we developed a high throughput screening assay based on fluorescence polarization to identify adiponectin ligands. The fluorescence polarization assay reported here could be adapted to screening against larger small molecular compound libraries. A natural product library containing 10,000 compounds was screened and 9 hits were selected for validation. These compounds have been taken for the second-step in vitro tests to confirm their agonistic activity. The most active adiponectin receptor 1 agonists are matairesinol, arctiin, (-)-arctigenin and gramine. The most active adiponectin receptor 2 agonists are parthenolide, taxifoliol, deoxyschizandrin, and syringin. These compounds may be useful drug candidates for hypoadiponectin related diseases. PMID:23691032

  19. Membrane order parameters for interdigitated lipid bilayers measured via polarized total-internal-reflection fluorescence microscopy.

    Science.gov (United States)

    Ngo, An T; Jakubek, Zygmunt J; Lu, Zhengfang; Joós, Béla; Morris, Catherine E; Johnston, Linda J

    2014-11-01

    Incorporating ethanol in lipid membranes leads to changes in bilayer structure, including the formation of an interdigitated phase. We have used polarized total-internal-reflection fluorescence microscopy (pTIRFM) to measure the order parameter for Texas Red DHPE incorporated in the ethanol-induced interdigitated phase (LβI) formed from ternary lipid mixtures comprising dioleoylphosphatidylcholine, cholesterol and egg sphingomyelin or dipalmitoylphosphatidylcholine. These lipid mixtures have 3 co-existing phases in the presence of ethanol: liquid-ordered, liquid-disordered and LβI. pTIRFM using Texas Red DHPE shows a reversal in fluorescence contrast between the LβI phase and the surrounding disordered phase with changes in the polarization angle. The contrast reversal is due to changes in the orientation of the dye, and provides a rapid method to identify the LβI phase. The measured order parameters for the LβI phase are consistent with a highly ordered membrane environment, similar to a gel phase. An acyl-chain labeled BODIPY-FL-PC was also tested for pTIRFM studies of ethanol-treated bilayers; however, this probe is less useful since the order parameters of the interdigitated phase are consistent with orientations that are close to random, either due to local membrane disorder or to a mixture of extended and looping conformations in which the fluorophore is localized in the polar headgroup region of the bilayer. In summary, we demonstrate that order parameter measurements via pTIRFM using Texas Red-DHPE can rapidly identify the interdigitated phase in supported bilayers. We anticipate that this technique will aid further research in the effects of alcohols and other additives on membranes.

  20. A new fluorescent squaraine probe for the measurement of membrane polarity.

    Science.gov (United States)

    Ioffe, Valeriya M; Gorbenko, Galyna P; Domanov, Yegor A; Tatarets, Anatoliy L; Patsenker, Leonid D; Terpetsching, Ewald A; Dyubko, Tatyana S

    2006-01-01

    The present study was undertaken to evaluate the sensitivity of newly synthesized squaraine dye 1 to the changes in lipid bilayer physical properties and compared it with the well-known dye 2. Partitioning of the dye 1 into lipid bilayer was found to be followed by significant increase of its fluorescence intensity and red-shift of emission maximum, while intensity of the dye 2 fluorescence increased only slightly on going from aqueous to lipidic environment. This suggests that dye 1 is more sensitive to the changes in membrane properties as compared to dye 2. Partition coefficients of the dye 1 have been determined for the model membranes composed of zwitterionic phospholipid phosphatidylcholine (PC) and its mixtures with positively charged detergent cetyltrimethylammonium bromide (CTAB), anionic phospholipid cardiolipin (CL), and sterol (Chol). The spectral responses of the dye 1 in different liposome media proved to correlate with the increase of bilayer polarity induced by Chol and CL or its decrease caused by CTAB. It was concluded that dye 1 can be used as fluorescent probe for examining membrane-related processes.

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

    Science.gov (United States)

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

    2016-06-01

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

  2. Measuring diffusion with polarization-modulation dual-focus fluorescence correlation spectroscopy.

    Science.gov (United States)

    Korlann, You; Dertinger, Thomas; Michalet, Xavier; Weiss, Shimon; Enderlein, Jörg

    2008-09-15

    We present a new technique, polarization-modulation dual-focus fluorescence correlation spectroscopy (pmFCS), based on the recently intro-duced dual-focus fluorescence correlation spectroscopy (2fFCS) to measure the absolute value of diffusion coefficients of fluorescent molecules at pico- to nanomolar concentrations. Analogous to 2fFCS, the new technique is robust against optical saturation in yielding correct values of the diffusion coefficient. This is in stark contrast to conventional FCS where optical saturation leads to an apparent decrease in the determined diffusion coefficient with increasing excitation power. However, compared to 2fFCS, the new technique is simpler to implement into a conventional confocal microscope setup and is compatible with cw-excitation, only needing as add-ons an electro-optical modulator and a differential interference contrast prism. With pmFCS, the measured diffusion coefficient (D) for Atto655 maleimide in water at 25?C is determined to be equal to (4.09 +/- 0.07) x 10(-6)cm(2)/s, in good agreement with the value of 4.04 x 10-6cm2/s as measured by 2fFCS.

  3. Interaction of alpha-lactalbumin with dimyristoyl phosphatidylcholine vesicles. II. A fluorescence polarization study.

    Science.gov (United States)

    Herreman, W; van Tornout, P; van Cauwelaert, F H; Hanssens, I

    1981-01-22

    The interaction of alpha-lactalbumin with dimyristoyl phosphatidylcholine vesicles was studied as a function of temperature, pH and the molar ratio of phospholipid to protein. The method consisted of measuring the fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene used as a probe embedded in the vesicles. After incubation of the protein with the phospholipid for 2 h at 23 degrees C, the polarization of the light emitted by this probe shifted to higher values; the shift was greater at acidic pH than at neutral pH. After incubation at 37 degrees C, no shift in polarization was found at pH 7, 6 and 5 while a strong increase occurred at pH 4. Lowering the temperature, after incubation at 37 degrees C, had little effect on the polarization at neutral pH. At pH 5, however, and in the transition range of the phospholipid, the polarization increased greatly. A kinetic study of the interaction carried out around the transition temperature of dimyristoyl phosphatidylcholine as a function of pH shows that the speed of complex formation between alpha-lactalbumin and the lipid increases from neutral to acidic pH. From the present results and in agreement with our earlier calorimetric and fluorescence data (Hanssens, I., Houthuys, C., Herreman, W. and van Cauwelaert, F.H. (1980) Biochim. Biophys, Acta 602, 539--557), it is concluded that at neutral pH the interaction mechanism is probably different from that at acidic pH. At neutral pH and at all temperatures, alpha-lactalbumin is mainly absorbed electrostatically to the outer surface of the vesicle with little or no influence on the transition temperature of the phospholipid. At this pH, only around the transition temperature is penetration possible. At pH 4, however, the protein is able to penetrate the vesicle at all temperatures and to interact hydrophobically with the phospholipid fatty acid chains. As a result of this interaction, the transition temperature is increased by about 4 degrees C. This different

  4. Communication: Angular momentum alignment and fluorescence polarization of alkali atoms photodetached from helium nanodroplets

    Energy Technology Data Exchange (ETDEWEB)

    Hernando, Alberto; Beswick, J. Alberto; Halberstadt, Nadine [LCAR-IRSAMC, Université Toulouse 3 - Paul Sabatier and CNRS, 31062 Toulouse (France)

    2013-12-14

    The theory of photofragments angular momentum polarization is applied to the photodetachment of an electronically excited alkali atom from a helium nanocluster (N = 200). The alignment of the electronic angular momentum of the bare excited alkali atoms produced is calculated quantum mechanically by solving the excited states coupled equations with potentials determined by density functional theory (DFT). Pronounced oscillations as a function of excitation energy are predicted for the case of Na@(He){sub 200}, in marked contrast with the absorption cross-section and angular distribution of the ejected atoms which are smooth functions of the energy. These oscillations are due to quantum interference between different coherently excited photodetachment pathways. Experimentally, these oscillations should be reflected in the fluorescence polarization and polarization-resolved photoelectron yield of the ejected atoms, which are proportional to the electronic angular momentum alignment. In addition, this result is much more general than the test case of NaHe{sub 200} studied here. It should be observable for larger droplets, for higher excited electronic states, and for other alkali as well as for alkali-earth atoms. Detection of these oscillations would show that the widely used pseudo-diatomic model can be valid beyond the prediction of absorption spectra and could help in interpreting parts of the dynamics, as already hinted by some experimental results on angular anisotropy of bare alkali fragments.

  5. Communication: angular momentum alignment and fluorescence polarization of alkali atoms photodetached from helium nanodroplets.

    Science.gov (United States)

    Hernando, Alberto; Beswick, J Alberto; Halberstadt, Nadine

    2013-12-14

    The theory of photofragments angular momentum polarization is applied to the photodetachment of an electronically excited alkali atom from a helium nanocluster (N = 200). The alignment of the electronic angular momentum of the bare excited alkali atoms produced is calculated quantum mechanically by solving the excited states coupled equations with potentials determined by density functional theory (DFT). Pronounced oscillations as a function of excitation energy are predicted for the case of Na@(He)200, in marked contrast with the absorption cross-section and angular distribution of the ejected atoms which are smooth functions of the energy. These oscillations are due to quantum interference between different coherently excited photodetachment pathways. Experimentally, these oscillations should be reflected in the fluorescence polarization and polarization-resolved photoelectron yield of the ejected atoms, which are proportional to the electronic angular momentum alignment. In addition, this result is much more general than the test case of NaHe200 studied here. It should be observable for larger droplets, for higher excited electronic states, and for other alkali as well as for alkali-earth atoms. Detection of these oscillations would show that the widely used pseudo-diatomic model can be valid beyond the prediction of absorption spectra and could help in interpreting parts of the dynamics, as already hinted by some experimental results on angular anisotropy of bare alkali fragments.

  6. Potential applications of near infrared auto-fluorescence spectral polarized imaging for assessment of food quality

    Science.gov (United States)

    Zhou, Kenneth J.; Chen, Jun

    2016-03-01

    The current growing of food industry for low production costs and high efficiency needs for maintenance of high-quality standards and assurance of food safety while avoiding liability issues. Quality and safety of food depend on physical (texture, color, tenderness etc.), chemical (fat content, moisture, protein content, pH, etc.), and biological (total bacterial count etc.) features. There is a need for a rapid (less than a few minutes) and accurate detection system in order to optimize quality and assure safety of food. However, the fluorescence ranges for known fluorophores are limited to ultraviolet emission bands, which are not in the tissue near infrared (NIR) "optical window". Biological tissues excited by far-red or NIR light would exhibit strong emission in spectral range of 650-1,100 nm although no characteristic peaks show the emission from which known fluorophores. The characteristics of the auto-fluorescence emission of different types of tissues were found to be different between different tissue components such as fat, high quality muscle food. In this paper, NIR auto-fluorescence emission from different types of muscle food and fat was measured. The differences of fluorescence intensities of the different types of muscle food and fat emissions were observed. These can be explained by the change of the microscopic structure of physical, chemical, and biological features in meat. The difference of emission intensities of fat and lean meat tissues was applied to monitor food quality and safety using spectral polarized imaging, which can be detect deep depth fat under the muscle food up to several centimeter.

  7. Long-wavelength fluorescence polarization immunoassay: determination of amikacin on solid surface and gliadins in solution.

    Science.gov (United States)

    Sánchez-Martínez, María Lourdes; Aguilar-Caballos, María Paz; Gómez-Hens, Agustina

    2007-10-01

    The versatility of the fluorescence polarization immunoassay (FPIA) is increased by using two long-wavelength labels, Nile Blue and a ruthenium(II) chelate. The first label has been used to study the potential of FPIA on a solid surface using dry reagent technology. The aminoglycoside antibiotic amikacin has been used as an analyte model, and the method has been applied to the analysis of serum samples. The second label has been used to show the practical application of FPIA to the determination of macromolecules, using gliadins as an analyte model, which have been determined in gluten-free food. Very low amounts of anti-amikacin antibodies and amikacin-Nile Blue tracer were immobilized onto nitrocellulose membranes, for the development of the amikacin method, and the consumption of reagents is lower than in conventional FPIA. Only the addition of the standard or sample extract at an adequate pH is required at the analysis time. The analyte displaces the tracer from the tracer-antibody immunocomplex, obtaining a decrease in the fluorescence polarization proportional to the analyte concentration. The gliadin-Ru(II) chelate tracer shows a relatively long lifetime, which allows the observation of differences in fluorescence polarization values between the tracer-antibody complex and the tracer alone. The dynamic range of the calibration graphs for both analytes is 0.5-10 microg mL-1 and the detection limits are 0.1 and 0.09 microg mL-1 for amikacin and gliadins, respectively. The study of the precision gave values of relative standard deviations lower than 5 and 1.5% for the amikacin and gliadin methods, respectively. Amikacin was determined in human serum samples using a previous deproteinization step with acetonitrile, obtaining recovery values in the range 83.4-122.8%. The gliadin method was applied to the analysis of gluten-free food samples by using a previous extraction step. The recovery study gave values between 94.3 and 105.0%.

  8. OPTIMIZATION OF LAMBLIASIS MICROSCOPIC DIAGNOSTICS BY THE METHOD OF POLARIZED FLUORESCENCE FOR PATIENTS WITH ROSACEA AND URTICARIAL

    Directory of Open Access Journals (Sweden)

    Maryana Kovalchuk

    2013-07-01

    Full Text Available Introduction: There is little information about diagnosis of concurrent lambliasis in patients with rosacea and urticaria. We used method of polarized fluorescence to diagnose liambliasis, taking into account belonging of macromolecular structures of unicellular parasites Giardia lamblia to the optically active substances with the properties of liquid crystals. Material and Methods: Lambliasis was diagnosed on the basis of feces parasitological research and duodenal contents by methods of light and optic microscopy and polarized fluorescence in 105 patients with rosacea and urticaria. Research results were processed by the method of variation statistics in the Statgraf program by using Student’s criterion. Results: Search results of lamblia in patients with rosacea and urticaria depended on the conditions of its holding, patients’ preparation and from the previously received basic therapy if it consisted absorbents. Due to the fact that the fluorescence polarization as a physical method does not require the use of any generally toxic, dye- fluorochromes, qualitative cyto fluorescent analysis of lamblia in greeting microdrugs enables to distinguish vegetative forms of cysts. Conclussions: Polarized fluorescence method allows optimize the microscopic diagnosis of lambliasis, increasing its sensitivity. Previous preparation for the laboratory examination of Giardia lamblia is needed for the best exposure of vermin for patients with rosacea and urticaria.

  9. Dynamics of bolaamphiphilic fluorescent polyenes in lipid bilayers from polarization emission spectroscopy.

    Science.gov (United States)

    Acuña, A Ulises; Amat-Guerri, Francisco; Quesada, Ernesto; Vélez, Marisela

    2006-06-20

    The rotational motions of the biamphiphilic polyenes (bolapolyenes) dimethyl all-(E)-octacosa-10,12,14,16,18-pentaenedioate (DE28:5) and dimethyl all-(E)-tetratriaconta-13,15,17,19,21-pentaenedioate (DE34:5), with head-to-head distances of 34 and 42A, respectively, have been examined by fluorescence anisotropy methods. The membrane-spanning bolapolyenes, which contain a central emitting pentaene group tethered to two methoxycarbonyl opposite polar heads by symmetric C(8) (DE28:5) and C(11) (DE34:5) polymethylene chains, were dispersed in lipid bilayers of DPPC or DMPC, and the stationary and picosecond-resolved emission was recorded as a function of temperature. In fluid-phase DMPC bilayers, three relaxation times could be determined, assigned to fast (0.2 and 2ns) single-bond isomerization processes localized on the alkyl chains, and to whole-molecule oscillations ( approximately 11ns), respectively. The anisotropy decay parameters were further analyzed in terms of a diffusive model for wobbling in a Gaussian ordering potential, to assess the anchoring effect of the symmetric polar heads. In this way, the average rotational diffusion constant of the bolapolyenes, D( perpendicular), could be estimated as 0.022-0.026rad(2) ns(-1) (DMPC bilayers, 35 degrees Celsius), a value that is only 1/3 of that corresponding to the related pentaene fatty acid spanning a single membrane monolayer. In contrast, the amplitude of the equilibrium orientational distribution (theta(half-cone) approximately 50 degrees ) is very similar for both the transmembrane and the single-headed polyenes. The reorientational oscillations of the central emitting group in the bolapolyenes necessarily would produce large-amplitude (2-5A) and very fast (ns) translational motions of the polar heads.

  10. A high throughout assay for human papillomavirus genotypes with fluorescence polarization

    Institute of Scientific and Technical Information of China (English)

    张菊; 闫小君; 孙建中; 陈中灿; 高艳娥; 白玉杰; 刘智广

    2003-01-01

    Objective To develop a simple, cheap, quick, accurate and practical method for a high throughout genotypes assay of human papillomavirus (HPV) DNA. Methods Crude DNA was extracted by a simplified proteinase K digesting method. HPV common conservative primers: GP5+/6+ system was used to amplify HPV DNA in 127 samples of condylomata acuminatum (CA) and cervical scrapes by PCR, then the PCR product was assayed using a template directing terminator incorporation (TDI) and genotypes were detected with fluorescence polarization (FP). Major HPVs type-specific probes (HPV6, 11, 16, 18, 31, 33, 35 and 58) designed by us were hybridized with the specific PCR products and a special fluorescent ddNTP terminator was directly added to the end of the probe under direction of specific PCR products. The results were measured with FP and compared with the results of the DNA sequence. Results Compared with the results of DNA sequencing, the results detected with fluorescence polarization were all correct. The proposed method could detect more than one type of HPV infection, but DNA sequencing method could not. The positive rate of HPV was 100% in 78 CA biopsies. Among them, there were 14 HPV double infections [HPV6B and 11 (9 cases), HPV11 and 16 (4), HPV11 and 18 (1)], 5 HPV triple infections [HPV6B,11 and 16 (4), HPV11,16 and 18 (1)], and one HPV quadruple infection (HPV6B, 11, 16 and 18). The positive rate of HPV was 77% in the 49 cervical scrapes. Six HPV double infections [HPV6B and 11 (2), HPV11 and 16 (1), HPV6B and 16 (1), HPV16 and 18 (1), HPV18 and 58 (1)], 3 HPV triple infections [HPV6B, 11 and 16 (2), HPV11,16 and 18 (1)] and one HPV quadruple infection (HPV6B,11,16 and 18) were detected in cervical cancer scrapes.Conclusions The proposed method allowed a high throughout, special, simple, rapid, automatic and economical detection of HPV-DNA genotyping without a use of labeling probes. It can detect multiple HPV genotype infection and will be and useful tool in HPV

  11. A fluorescence polarization based screening assay for identification of small molecule inhibitors of the PICK1 PDZ domain

    DEFF Research Database (Denmark)

    Thorsen, Thor S; Madsen, Kenneth L; Dyhring, Tino

    2011-01-01

    PDZ (PSD-95/Discs-large/ZO-1 homology) domains represent putative targets in several diseases including cancer, stroke, addiction and neuropathic pain. Here we describe the application of a simple and fast screening assay based on fluorescence polarization (FP) to identify inhibitors of the PDZ...

  12. A reusable and sensitive biosensor for total mercury in canned fish based on fluorescence polarization.

    Science.gov (United States)

    Shen, Tongfei; Yue, Qiaoli; Jiang, Xiuxiu; Wang, Lei; Xu, Shuling; Li, Haibo; Gu, Xiaohong; Zhang, Shuqiu; Liu, Jifeng

    2013-12-15

    In this work, we developed a sensitive and selective sensor technique for total mercury (Hg) detection in canned fish samples based on the fluorescence polarization (FP) method. The detection principle was that ssDNA containing thymine (T) bases was modified on magnetic nanoparticles (MNPs), which were used as enhancement probe. In the presence of Hg(2+), the ssDNA on MNPs can hybridize with the fluorophore labeled aptamer owing to the specific interaction between T bases and Hg(2+). The formation of thymine-Hg(2+)-thymine (T-Hg(2+)-T) complexes leads to the molar mass increase of fluorophore molecules, resulting in the enhancement of FP signal. The increase of FP was in a good linearity with the concentration of Hg(2+) in range of 2.0 nM-1.0 mM and the limit of detection was 0.49 nM (3.29 SB/m, according to the recent recommendation of IUPAC). Moreover, the proposed biosensor can be reused for 6 cycling times and was successfully applied in monitoring Hg(2+) in real samples.

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

    Science.gov (United States)

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

    1996-01-01

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

  14. DART: Recent Advances in Remote Sensing Data Modeling With Atmosphere, Polarization, and Chlorophyll Fluorescence

    Science.gov (United States)

    Gastellu-Etchegorry, Jean-Phil; Lauret, Nicolas; Yin, Tiangang; Landier, Lucas; Kallel, Abdelaziz; Malenovsky, Zbynek; Bitar, Ahmad Al; Aval, Josselin; Benhmida, Sahar; Qi, Jianbo; hide

    2017-01-01

    To better understand the life-essential cycles and processes of our planet and to further develop remote sensing (RS) technology, there is an increasing need for models that simulate the radiative budget (RB) and RS acquisitions of urban and natural landscapes using physical approaches and considering the three-dimensional (3-D) architecture of Earth surfaces. Discrete anisotropic radiative transfer (DART) is one of the most comprehensive physically based 3-D models of Earth-atmosphere radiative transfer, covering the spectral domain from ultraviolet to thermal infrared wavelengths. It simulates the optical 3-DRB and optical signals of proximal, aerial, and satellite imaging spectrometers and laser scanners, for any urban and/or natural landscapes and for any experimental and instrumental configurations. It is freely available for research and teaching activities. In this paper, we briefly introduce DART theory and present recent advances in simulated sensors (LiDAR and cameras with finite field of view) and modeling mechanisms (atmosphere, specular reflectance with polarization and chlorophyll fluorescence). A case study demonstrating a novel application of DART to investigate urban landscapes is also presented.

  15. Rapid and high throughput detection of HBV YMDD mutants with fluorescence polarization

    Institute of Scientific and Technical Information of China (English)

    Yui-Jie Bai; Jin-Rong Zhao; Guan-Ting Lv; Wen-Hong Zhang; Yan Wang; Xiao-Jun Yan

    2003-01-01

    AIM: To develop a simple and rapid detection of HBV gene variants and prediction of lamivudine-resistance in patients.METHODS: Initially, plasmids harboring the wild-type or mutant HBV DNA fragments were used in a model system.The technique was then applied to clinical samples for an analysis of YMDD mutations. The sera were extracted from chronic hepatitis patients who had received lamivudine treatment for more than one year. P region gene of HBV was amplified by polymerase chain reaction. The excess primers and dNTPs in PCR products were removed by cleaning-up reagents. Template-directed dye-terminator incorporation reaction was performed and R110 or TAMRA labeled acyclo-terminator was added on the 3' end of TDIprimer specifically. Fluorescence polarization value was measured with Victor 2 multilabel counter and the genotypes of HBV were analyzed.RESULTS: The YMDD genotypes in recombined positive plasmid and 56 serum samples of HBV infected patients were analyzed by using our TDI-FP method and the specificity and sensitivity were confirmed by DNA sequencing. Five of 56 serum samples showed YVDD phenotype (9%), including 1 YMDD and YVDD mixed infection. Four of 56 showed YIDD phenotype (7.1%).CONCLUSION: This is a simple, rapid, low cost and high throughput assay to detect HBV polymerase gene variants and suitable for large-scale screening and prediction of the lamivudine-resistance in clinical samples.

  16. Rapid screening of aflatoxin B1 in beer by fluorescence polarization immunoassay.

    Science.gov (United States)

    Beloglazova, N V; Eremin, S A

    2015-09-01

    This manuscript describes the development of a sensitive, fast and easily-performed fluorescence polarization immunoassay (FPIA) for the mycotoxin aflatoxin B1 (AFB1) in various beer samples, both lager and dark. The highest sensitivity was determined for six poly- and monoclonal antibodies selective towards aflatoxins. The sample pretreatment design was emphasized since beer samples are characterized by extremely diverse matrices. Herein, the choice of sorbent for effective removal of matrix interferences prior to analysis was crucial. The samples were diluted with a borate buffer solution containing 1% PEG 6000 and passed through the clean-up column packed with NH2-derivated silica. This sample pretreatment technique was perfectly suitable for the FPIA of lager beer samples, but for dark beer and ale it did not suffice. An artificial matrix was constructed to plot a calibration curve and quantify the results of the latter samples. The developed immunoassay was characterized by a limit of detection of 1 ng mL(-1). Apparent recovery values of 89-114% for lager and 80-125% for dark beer were established. The FPIA data for AFB1 was characterized by elevated linear regression coefficients, 0.9953 for spiked lager and 0.9895 for dark beer samples respectively.

  17. AcycloPrime: a novel method for SNP analysis using fluorescence polarization

    Science.gov (United States)

    Greene, Richard A.; DiMeo, James J.; Malone, Mary E.; Swartwout, Suzanne; Liu, Jianzhao; Buzby, Philip R.

    2002-06-01

    Single nucleotide polymorphisms (SNPs) are the most common type of genetic variation between individuals of a species and are therefore thought to be responsible for a large part of individual phenotypic variation. It has been estimated that a SNP may occur every 100-300 bases in the human genome. Research on human SNPs is expected to facilitate genetic mapping studies that may lead to a better understanding of the genetic basis for complex diseases and individual variation in drug metabolism. We have developed a novel assay for the identification of known SNPs using primer extension with the novel AcycloTerminators and a new thermostable polymerase, AcycloPol, in a homogeneous fluorescence polarization (FP) format. All assay steps can be performed in the same well of either a 384- or 96-well PCR-compatible microplate. FP provides several advantages, including simplicity and low reagent cost. The homogeneous assay format eliminates any need for separation or washing steps and is amenable to automation.

  18. Screening for Antifibrotic Compounds Using High Throughput System Based on Fluorescence Polarization

    Directory of Open Access Journals (Sweden)

    Branko Stefanovic

    2014-04-01

    Full Text Available Fibroproliferative diseases are one of the leading causes of death worldwide. They are characterized by reactive fibrosis caused by uncontrolled synthesis of type I collagen. There is no cure for fibrosis and development of therapeutics that can inhibit collagen synthesis is urgently needed. Collagen α1(I mRNA and α2(I mRNA encode for type I collagen and they have a unique 5' stem-loop structure in their 5' untranslated regions (5'SL. Collagen 5'SL binds protein LARP6 with high affinity and specificity. The interaction between LARP6 and the 5'SL is critical for biosynthesis of type I collagen and development of fibrosis in vivo. Therefore, this interaction represents is an ideal target to develop antifibrotic drugs. A high throughput system to screen for chemical compounds that can dissociate LARP6 from 5'SL has been developed. It is based on fluorescence polarization and can be adapted to screen for inhibitors of other protein-RNA interactions. Screening of 50,000 chemical compounds yielded a lead compound that can inhibit type I collagen synthesis at nanomolar concentrations. The development, characteristics, and critical appraisal of this assay are presented.

  19. Localization of hypericin-induced fluorescence after Hypericum perforatum polar fraction instillation in normal rat urinary bladder

    Science.gov (United States)

    Stavropoulos, Nikos E.; Skalkos, Dimitris; Tsimaris, Ioannis; Kalogeras, D.; Nseyo, Unyime O.; Batistatou, A.; Agnantis, N. J.

    2005-04-01

    The photodynamic action of the Hypericum perforatum L. extract, mainly its polar methanolic fraction (PMF) has recently been substantiated by our group. The herb contains a number of naphthodianthrones - photosensitizers mainly hypericin and pseudohypericin. The concentration of hypericins in PMF was found to be 1.37 %. The distribution of hypericins fluorescence in sections of normal rat bladder tissues after the intravesical instillation of the polar methanolic fraction of hypericum (PMF) was studied by the use of fluorescence microscopy. PMF was dissolved in normal saline containing 0.5 μg/ml concentration of hypericins, and was then instilled in rat bladder for 15, 30, 60 and 120 minutes respectively. PMF solutions were withdrawn, bladders were rinsed through the catheter with normal saline and rats were sacrificed. Bladders were then removed, cut open and immediately mounted in medium, and immersed in liquid nitrogen. Two consecutive 3-μm frozen sections were cut with a cryostat. The first section was examined by fluorescence microscopy and the second section was stained with hematoxylin and eosin. For fluorescence imaging the filter set used included a 535/50 nm bandpass excitation filter and a 610/75 nm emission filter. Fluorescence images were acquired and documented using photography. Fluorescene could be detected in bladder samples after only 15 minutes of instillation with the above described solution. The urothelium / muscle fluorescence ratio ranged from 5/1 to 11/1 in various sites of the samples examined. No fluorescence originating from the muscle could be detected. PMF should be further studied towards the direction of its use in photodynamic therapy.

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

    Science.gov (United States)

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

    2017-01-01

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

  1. Preparation and application of new fluorescein-labeled fumonisins B1 in fluorescence polarization analysis technique

    Science.gov (United States)

    Objective: To prepare a new fluorescent tracer against common mycotoxins such as fumonisin B1 in order to replace 6-(4,6-Dichlorotriazinyl) aminofluorescein (6-DTAF), an expensive marker, and to develop a technique for quick detection of fumonisin B1 based on the principle of fluorescence polarizati...

  2. Ultrafast polarized fluorescence measurements on monomeric and self-associated melittin

    NARCIS (Netherlands)

    Pandit, A.; Larsen, O.F.A.; Stokkum, van I.H.M.; Grondelle, van R.; Kraayenhof, R.; Amerongen, van H.

    2003-01-01

    The anisotropic and magic-angle fluorescence decay of the single tryptophan (Trp) residue of melittin, a bee venom peptide, was investigated by time-resolved fluorescence anisotropy using a streak camera setup. The peptide was dissolved either in distilled water or in Hepes/NaOH buffer containing lo

  3. Simultaneous determination of multiple (fluoro)quinolone antibiotics in food samples by a one-step fluorescence polarization immunoassay.

    Science.gov (United States)

    Mi, Tiejun; Wang, Zhanhui; Eremin, Sergei A; Shen, Jianzhong; Zhang, Suxia

    2013-10-02

    This paper describes a rapid one-step fluorescence polarization immunoassay (FPIA) for the simultaneous determination of multiple (fluoro)quinolone antibiotics (FQs) in food samples. Several fluorescent tracers were synthesized and evaluated in the FPIA method based on a broad-specificity of monoclonal antibodies toward FQs. The heterogeneous tracer, SAR-5-FAM, was considered as the optimal choice to prepare the immunocomplex single reagent, which allows a rapid and sensitive displacement reaction by addition of analytes. Optimized single-reagent FPIA exhibited broad cross-reactivities in the range of 7.8-172.2% with 16 FQs tested and was capable of determining most FQs at the level of maximum residue limits. Recoveries for spiked milk and chicken muscle samples were from 77.8 to 116%, with relative standard deviation lower than 17.4%. Therefore, this method could be applicable in routine screening analysis of multiple FQ residues in food samples.

  4. Fluorescence emission and polarization analyses for evaluating binding of ruthenium metalloglycocluster to lectin and tetanus toxin c-fragment

    Science.gov (United States)

    Okada, Tomoko; Minoura, Norihiko

    2010-02-01

    We have developed a fluorescent ruthenium metalloglycocluster as a powerful molecular probe for evaluating a binding event between carbohydrates and lectins by fluorescence emission (FE) and fluorescence polarization (FP) analysis. The fluorescent ruthenium metalloglycoclusters, [Ru(bpy-2Gal)3] and [Ru(bpy-2Glc)3], possess clustered galactose and glucose surrounding the ruthenium center. Changes in FE and FP of these metalloglycoclusters were measured by adding each lectin (Peanut agglutinin (PNA), Ricinus communis agglutinin 120 (RCA), Concanavalin A (ConA), or Wheat germ agglutinin (WGA)) or tetanus toxin c-fragment (TCF). Following the addition of PNA, the FE spectrum of [Ru(bpy- 2Gal)3] showed new emission peak and the FP value of [Ru(bpy-2Gal)3] increased. Similarly, the FE spectrum of [Ru(bpy-2Glc)3] showed new emission peak and the FP value increased following the addition of ConA. Since other combinations of the metalloglycoclusters and lectin caused little change, specific bindings of galactose to PNA and glucose to ConA were proved by the FE and FP measurement. From nonlinear least-squares fitting, dissociation constants (Kd) of [Ru(bpy-2Gal)3] to PNA was 6.1 μM, while the Kd values of [Ru(bpy)2(bpy-2Gal)] to PNA was ca. 10-4 M. Therefore, the clustered carbohydrates were proved to increase affinity to lectins. Furthermore, the FP measurements proved specific binding of [Ru(bpy-2Gal)3] to TCF.

  5. Resonance fluorescence of a two-level quantum emitter near a plasmonic nanoparticle: role of the near-field polarization

    Science.gov (United States)

    Vladimirova, Yu V.; Chubchev, E. D.; Zadkov, V. N.

    2017-02-01

    It is demonstrated that the interaction of a two-level quantum emitter (atom, molecule, etc) with a plasmonic nanoparticle (prolate nanospheroid) in an external laser field features either an essential increase (up to a few orders of magnitude) or reduction (up to a few times) of the total decay rate of the emitter in specific areas around the nanoparticle in contrast to its decay rate in a vacuum. It is also shown that the resonance fluorescence spectrum of the emitter in close proximity to a plasmonic nanoparticle is very sensitive to both the location of the emitter around the nanoparticle and to polarization of the near-field, which depends in turn on the polarization of the incident laser field. This can be used in engineering potential quantum optics experiments with quantum emitters in the near-field, as well as for 3D nanoscopy of the near-field by registering the resonance fluorescence spectra of quantum emitters scattered in the vicinity of a plasmonic nanoparticle.

  6. [Development and evaluation of a serological protocol of fluorescence polarization for the preliminary study of Brucella spp antibodies in humans].

    Science.gov (United States)

    Sánchez-Villalobos, Alfredo; Urdaneta-Fernández, Margelys; Rubio-Fuenmayor, Elí; Molero-Saras, Gladys; Luzardo-Charris, Carlos; Corona-Mengual, Carlos

    2011-03-01

    In order to show the development and scope of a serological analysis method based on fluorescence polarization assay (FPA) from a drop of blood obtained by the capillary technique, a Brucella antibody assay was performed on a group of 321 high-risk workers. The results were compared with data from the analysis of blood serum by FPA and a competitive enzyme immunoassay (ELISA-c). The number of concordance was 318 (99.06%), and discordant 3 (0.93%), which were negative in serum by fluorescence polarization (FPAs) and ELISA-c, but positive with capillary FPA (FPAc). The comparative results FPAc were: sensitivity 100%; specificity: 99.05%; positive predictive value 66.67%; negative predictive value 100.0%; false positive rate: 0.95%; false negative rate: 0%; accuracy: 98.0%; odds ratio: 203.00. The youden J for both FPA methods was 0.667. The identification was considered reliable and the correlation of both procedures, FPA and ELISA-c, was no statistically different (P > 0.05%), which allows to highly recommend the study implementation of human brucellosis with capillary blood as a preliminary method.

  7. Analysis of local polarity change around Cys34 in bovine serum albumin during N→B transition by a polarity-sensitive fluorescence probe

    Science.gov (United States)

    Wang, Xiaochun; Guo, Lihong; Ma, Huimin

    2009-09-01

    The change trend of the local environment of Cys34 domain in bovine serum albumin has been studied as a function of pH value by using thiol-specific and polarity-sensitive fluorescent probe 3-(4-chloro-6- p-maleimidylphenoxyl-1,3,5-triazinylamino)-7-dimethylamino-2-methyl-phenazine. The local polarity of the Cys34 domain is found to rise with the increase of pH values, and the corresponding dielectric constant is raised from 12.8 at pH 6.0 to 23.3 at pH 9.1. The result shows that the environment of the Cys34 domain is rather hydrophobic in normal state at pH 6.0 and becomes a little hydrophilic in the course of N→B transition, which may be attributed to the slight unfolding of the protein and thus the increasing of exposure of the previously relatively buried Cys34. In addition, the increased dielectric constant (23.3) is much lower than that (80.1) of water, suggesting that the unfolding of bovine serum albumin does not cause the full exposure of the Cys34 to the aqueous media during the transition.

  8. Synthetic Control of the Excited-State Dynamics and Circularly Polarized Luminescence of Fluorescent "Push-Pull" Tetrathia[9]helicenes.

    Science.gov (United States)

    Yamamoto, Yuki; Sakai, Hayato; Yuasa, Junpei; Araki, Yasuyuki; Wada, Takehiko; Sakanoue, Tomo; Takenobu, Taishi; Kawai, Tsuyoshi; Hasobe, Taku

    2016-03-14

    A series of fluorescent "push-pull" tetrathia[9]helicenes based on quinoxaline (acceptor) fused with tetrathia[9]helicene (donor) derivatives was synthesized for control of the excited-state dynamics and circularly polarized luminescence (CPL) properties. In this work, introduction of a quinoxaline onto the tetrathia[9]helicene skeleton induced the "push-pull" character, which was enhanced by further introduction of an electron-releasing Me2 N group or an electron-withdrawing NC group onto the quinoxaline unit (denoted as Me2 N-QTTH and NC-QTTH, respectively). These trends were successfully discussed in terms of by electrochemical measurements and density functional theory (DFT) calculations. As a consequence, significant enhancements in the fluorescence quantum yields (ΦFL ) were achieved. In particular, the maximum ΦFL of Me2 N-QTTH was 0.43 in benzene (NC-QTTH: ΦFL =0.30), which is more than 20 times larger than that of a pristine tetrathia[9]helicene (denoted as TTH; ΦFL =0.02). These enhancements were also explained by kinetic discussion of the excited-state dynamics such as fluorescence and intersystem crossing (ISC) pathways. Such significant enhancements of the ΦFL values thus enabled us to show the excellent CPL properties. The value of anisotropy factor gCPL (normalized difference in emission of right-handed and left-handed circularly polarized light) was estimated to be 3.0 × 10(-3) for NC-QTTH. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Directory of Open Access Journals (Sweden)

    Pretty Iain A

    2012-05-01

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

  10. Quantitative light fluorescence (QLF) and polarized white light (PWL) assessments of dental fluorosis in an epidemiological setting.

    Science.gov (United States)

    Pretty, Iain A; McGrady, Michael; Zakian, Christian; Ellwood, Roger P; Taylor, Andrew; Sharif, Mohammed Owaise; Iafolla, Timothy; Martinez-Mier, E Angeles; Srisilapanan, Patcharawan; Korwanich, Narumanas; Goodwin, Michaela; Dye, Bruce A

    2012-05-20

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

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

    Science.gov (United States)

    2012-01-01

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

  12. Fluorescence emission and polarization analyses for evaluating binding of ruthenium metalloglycoclusters to lectins and tetanus toxin C-fragment

    Science.gov (United States)

    Okada, Tomoko; Minoura, Norihiko

    2011-03-01

    We develop a fluorescent ruthenium metalloglycocluster for use as a powerful molecular probe in evaluating the binding between carbohydrates and lectins by fluorescence emission (FE) and fluorescence polarization (FP) analyses. Changes in the FE and FP of these metalloglycoclusters are measured following the addition of lectin [peanut agglutinin (PNA), Ricinus communis agglutinin 120, Concanavalin A (ConA), or wheat germ agglutinin] or tetanus toxin c-fragment (TCF). After the addition of PNA, the FE spectrum of [Ru(bpy-2Gal)3] shows a new emission peak and the FP value of [Ru(bpy-2Gal)3] increases. Similarly, the FE spectrum of [Ru(bpy-2Glc)3] shows a new emission peak and the FP value increases on addition of ConA. Because other combinations of metalloglycoclusters and lectins show little change, specific binding of galactose to PNA and that of glucose to ConA are confirmed by the FE and FP measurements. Resulting dissociation constants (Kd) prove that the metalloglycoclusters with highly clustered carbohydrates show higher affinity for the respective lectins than those with less clustered carbohydrates. Furthermore, specific binding of [Ru(bpy-2Gal)3] to TCF was confirmed by the FP measurement.

  13. Evaluation of Silver and Gold Nanoparticles on Polyester Fibers by Fluorescent Polarization Raman Spectra

    Directory of Open Access Journals (Sweden)

    V.M. Emelyanov

    2014-07-01

    Full Text Available The results of the validation of identification nanoparticle colloidal silver and gold on the polyester fibers on the background component of the Raman spectra in the control based on the polarization characteristics. The accuracy of identification of nanoparticles was evaluated by the joint probability of crossing normal scatter intensity distributions Raman spectrograms as silver nanoparticles and gold nanoparticles on polyester fibers, depending on the longitudinal and transverse polarization of the laser radiation on the entire range of wave numbers. Defined generalized parameter values common to distributions over the entire range for each wave numbers with the polarization of the laser and across the grain, and generalized reliability of the control and identification of nanoparticles of silver, gold for assessing the likelihood of the complete group of events. Set the sensitivity of detection reliability.

  14. Fluorescence polarization immunoassay using IgY antibodies for detection of valnemulin in swine tissue

    Science.gov (United States)

    Immunoglobulin Y (IgY) is derived from egg yolk and has been identified as a cheap and high-yield immunoreagent. The application of IgY in immunoassay for the detection of chemical contaminants in food samples has rarely been reported. In this work, we describe a rapid and sensitive fluorescence p...

  15. Structural Changes of Yellow Cameleon Domains Observed by Quantitative FRET Analysis and Polarized Fluorescence Correlation Spectroscopy

    NARCIS (Netherlands)

    Borst, J.W.; Laptenok, S.; Westphal, A.H.; Kühnemuth, R.; Hornen, H.; Visser, N.V.; Kalinin, S.; Aker, J.C.M.; Hoek, van A.; Seidel, C.A.M.; Visser, A.J.W.G.

    2008-01-01

    Förster resonance energy transfer (FRET) is a widely used method for monitoring interactions between or within biological macromolecules conjugated with suitable donor-acceptor pairs. Donor fluorescence lifetimes in absence and presence of acceptor molecules are often measured for the observation of

  16. Fluorescence confocal polarizing microscopy: Three-dimensional imaging of the director

    Indian Academy of Sciences (India)

    O D Lavrentovich

    2003-08-01

    Much of the modern understanding of orientational order in liquid crystals (LCs) is based on polarizing microscopy (PM). A PM image bears only two-dimensional (2D) information, integrating the 3D pattern of optical birefringence over the path of light. Recently, we proposed a technique to image 3D director patterns by fluorescence confocal polarizing microscopy (FCPM). The technique employs the property of LC to orient the fluorescent dye molecules of anisometric shape, added in small quantities to the LC. In LC, smooth director deformations do not alter mass density of the material. Thus the density of dye is also uniform across the sample, except, perhaps, near the surfaces or at the cores of topological defects. In polarized light, the measured fluorescence signal is determined by the spatial orientation of the molecules rather than by dye concentration (as in regular biological samples stained with tissue-specific dyes). The contrast is enhanced when both excitation and detection of fluorescence light are performed in polarized light. This short review describes the essence of FCPM technique and illustrates some of its applications, including imaging of Frederiks electric-field induced effect in a nematic LC and defects such as dislocations in cholesteric LCs.

  17. Monitoring changes in membrane polarity, membrane integrity, and intracellular ion concentrations in Streptococcus pneumoniae using fluorescent dyes.

    Science.gov (United States)

    Clementi, Emily A; Marks, Laura R; Roche-Håkansson, Hazeline; Håkansson, Anders P

    2014-02-17

    Membrane depolarization and ion fluxes are events that have been studied extensively in biological systems due to their ability to profoundly impact cellular functions, including energetics and signal transductions. While both fluorescent and electrophysiological methods, including electrode usage and patch-clamping, have been well developed for measuring these events in eukaryotic cells, methodology for measuring similar events in microorganisms have proven more challenging to develop given their small size in combination with the more complex outer surface of bacteria shielding the membrane. During our studies of death-initiation in Streptococcus pneumoniae (pneumococcus), we wanted to elucidate the role of membrane events, including changes in polarity, integrity, and intracellular ion concentrations. Searching the literature, we found that very few studies exist. Other investigators had monitored radioisotope uptake or equilibrium to measure ion fluxes and membrane potential and a limited number of studies, mostly in Gram-negative organisms, had seen some success using carbocyanine or oxonol fluorescent dyes to measure membrane potential, or loading bacteria with cell-permeant acetoxymethyl (AM) ester versions of ion-sensitive fluorescent indicator dyes. We therefore established and optimized protocols for measuring membrane potential, rupture, and ion-transport in the Gram-positive organism S. pneumoniae. We developed protocols using the bis-oxonol dye DiBAC4(3) and the cell-impermeant dye propidium iodide to measure membrane depolarization and rupture, respectively, as well as methods to optimally load the pneumococci with the AM esters of the ratiometric dyes Fura-2, PBFI, and BCECF to detect changes in intracellular concentrations of Ca(2+), K(+), and H(+), respectively, using a fluorescence-detection plate reader. These protocols are the first of their kind for the pneumococcus and the majority of these dyes have not been used in any other bacterial

  18. Investigation of β-lactam antibacterial drugs, β-lactamases, and penicillin-binding proteins with fluorescence polarization and anisotropy: a review

    Science.gov (United States)

    Shapiro, Adam B.

    2016-06-01

    This review covers the uses of fluorescence polarization and anisotropy for the investigation of bacterial penicillin binding proteins (PBPs), which are the targets of β-lactam antibacterial drugs (penicillins, cephalosporins, carbapenems, and monobactams), and of the β-lactamase enzymes that destroy these drugs and help to render bacterial pathogens resistant to them. Fluorescence polarization and anisotropy-based methods for quantitation of β-lactam drugs are also reviewed. A particular emphasis is on methods for quantitative measurement of the interactions of β-lactams and other inhibitors with PBPs and β-lactamases.

  19. Polarized fluorescence measurements of orientational order in a uniaxial liquid crystal

    DEFF Research Database (Denmark)

    Chapoy, L. Lawrence; DuPré, Donald B.

    1979-01-01

    The second and fourth orientational order parameters and , have been measured throughout the liquid crystalline phase of p-methoxybenzylidene-p[prime]-n-butylaniline (MBBA) using small quantities of a fluorescent probe. Complications of rotational Brownian motion and the intramolecular transfer...... of excitation energy were considered in the analysis. The results are in agreement with previous Raman measurements on the doped liquid crystal. The Journal of Chemical Physics is copyrighted by The American Institute of Physics....

  20. Determination of the Dipole Geometry of Fluorescent Nanoparticles Using Polarized Excitation and Emission Analysis.

    Science.gov (United States)

    Li, Jianan; Kwok, Ka-Cheung; Cheung, Nai-Ho

    2016-02-01

    We demonstrate that the geometries of the absorption dipole μab and emission dipole μem of nano-emitters such as quantum dots can be determined simultaneously by far-field polarimetry. The method involves plotting the emission polarization ratio against the absorption polarization ratio of single nano-emitters. Using Monte Carlo simulation, we show that these plots depend sensitively on the aspect ratio of the dipole shape. For example, the so-called 3D-2D dipole combination, that is, μab of radius ratio 1:1:1 and μem of ratio 1:1:0, would give rise to a vertical line plot. Polarization ratios of commercial cadmium selenide/zinc sulfide (CdSe/ZnS) quantum dots are measured and plotted. The empirical data points are best-fitted to yield μab of radius ratio 1:1:0.28 and μem of ratio 1:1:0.

  1. Improvement of inhibitor identification for heat shock protein 90α by utilizing a red-shifted fluorescence polarization probe.

    Science.gov (United States)

    Qian, Jie; Holskin, Beverly P; Theroff, Jay; Underiner, Ted; Meyer, Sheryl L; Angeles, Thelma S

    2012-08-01

    Heat shock protein-90 (HSP90) is an ATP-dependent molecular chaperone with intrinsic ATPase activity. HSP90 is required for the stability and function of client proteins, many of which are involved in oncogenesis. Thus, identification of HSP90 inhibitors would potentially lead to the discovery of cancer therapeutics. Here, we present a high-throughput screening campaign utilizing two geldanamycin (GM)-labeled probes in a fluorescence polarization (FP) assay. For the primary screen, a previously reported green BODIPY-labeled GM (GM-BODIPY) was used to evaluate a library collection of about 400,000 compounds. From this screen, 3058 compounds showed >30% inhibition. To distinguish true positives from compound interference, a confirmatory screen was deemed necessary. Accordingly, a red-shifted FP binding assay was developed using GM labeled with red BODIPY. This tool enabled reliable identification of promising HSP90α inhibitors.

  2. High-throughput 1,536-well fluorescence polarization assays for α(1-acid glycoprotein and human serum albumin binding.

    Directory of Open Access Journals (Sweden)

    Adam Yasgar

    Full Text Available Two major plasma proteins in humans are primarily responsible for drug binding, the α(1-acid-glycoprotein (AGP and human serum albumin (HSA. The availability of at least a semiquantitative high-throughput assay for assessment of protein binding is expected to aid in bridging the current gap between high-throughput screening and early lead discovery, where cell-based and biochemical assays are deployed routinely to test up to several million compounds rapidly, as opposed to the late-stage candidate drug profiling methods which test at most dozens of compounds at a time. Here, we describe the miniaturization of a pair of assays based on the binding- and displacement-induced changes in fluorescence polarization (FP of fluorescent small molecule probes known to specifically target the drug-binding sites of these two proteins. A robust and reproducible assay performance was achieved in ≤4 µL assay volume in 1,536-well format. The assays were tested against a validation set of 10 known protein binders, and the results compared favorably with data obtained using protein-coated beads with high-performance liquid chromatography analysis. The miniaturized assays were taken to a high-throughput level in a screen of the LOPAC(1280 collection of 1,280 pharmacologically active compounds. The adaptation of the AGP and HSA FP assays to a 1,536-well format should allow their use in early-stage profiling of large-size compound sets.

  3. Growth, polarized Raman and fluorescence properties of TbCa4O(BO3)3 single crystal

    Science.gov (United States)

    Yuan, Dongsheng; Gao, Zeliang; Jia, Zhitai; Shu, Jun; Li, Yang; Tao, Xutang

    2015-04-01

    A single crystal of TbCa4O(BO3)3 (TbCOB) with diameter of 35 mm and length of 80 mm has been successfully grown using the Czochralski (Cz) method. The polarized Raman spectra were studied to analyze the vibrational structure of TbCOB, especially the modes from [BO3]3- triangles that are responsible for the nonlinear optical generation. The fluorescence properties of the X-cut, Y-cut, and Z-cut non-centrosymmetric TbCOB crystals were measured for the first time, and both f-d and f-f transitions were identified according to the energy level diagram. Based on the non-radiative energy transfer process, TbCOB crystal shows the characteristic emission of Tb3+ corresponding to 5D4 → 7F6,5,4,3 transitions with the green light of 542 nm (5D4 → 7F5) being the most prominent group. Additionally, the lifetime decay indicates single exponential character for the excited wavelength at 378 nm, following the result of τ = 2.07 ms at room temperature. The long fluorescence lifetime and good spectra properties of TbCOB single crystal indicate its potential optical prospects.

  4. High-throughput fluorescence polarization assay for chemical library screening against anti-apoptotic Bcl-2 family member Bfl-1.

    Science.gov (United States)

    Zhai, Dayong; Godoi, Paulo; Sergienko, Eduard; Dahl, Russell; Chan, Xochella; Brown, Brock; Rascon, Justin; Hurder, Andrew; Su, Ying; Chung, Thomas D Y; Jin, Chaofang; Diaz, Paul; Reed, John C

    2012-03-01

    Overexpression of the anti-apoptotic Bcl-2 family proteins occurs commonly in human cancers. Bfl-1 is highly expressed in some types of malignant cells, contributing significantly to tumor cell survival and chemoresistance. Therefore, it would be desirable to have chemical antagonists of Bfl-1. To this end, we devised a fluorescence polarization assay (FPA) using Bfl-1 protein and fluorescein-conjugated Bid BH3 peptide, which was employed for high-throughput screening of chemical libraries. Approximately 66 000 compounds were screened for the ability to inhibit BH3 peptide binding to Bfl-1, yielding 14 reproducible hits with ≥50% displacement. After dose-response analysis and confirmation using a secondary assay based on time-resolved fluorescence resonance energy transfer (TR-FRET), two groups of Bfl-1-specific inhibitors were identified, including chloromaleimide and sulfonylpyrimidine series compounds. FPAs generated for each of the six anti-apoptotic Bcl-2 proteins demonstrated selective binding of both classes of compounds to Bfl-1. Analogs of the sulfonylpyrimidine series were synthesized and compared with the original hit for Bfl-1 binding by both FPAs and TR-FRET assays. The resulting structure-activity relation analysis led to the chemical probe compound CID-2980973 (ML042). Collectively, these findings demonstrate the feasibility of using the HTS assay for discovery of selective chemical inhibitors of Bfl-1.

  5. Amphetamine concentrations in human urine following single-dose administration of the calcium antagonist prenylamine-studies using fluorescence polarization immunoassay (FPIA) and GC-MS.

    Science.gov (United States)

    Kraemer, Thomas; Roditis, Susanne K; Peters, Frank T; Maurer, Hans H

    2003-03-01

    Prenylamine (R,S-N-(3,3-diphenylpropyl-methyl-2-phenethylamine), a World Health Organization class V calcium antagonist, is known to be metabolized to amphetamine. In this study, amphetamine concentrations after a single-dose administration of prenylamine were determined to check if they reached values that could be of analytical and/or pharmacological importance in clinical and forensic toxicology. Enantiomeric composition of amphetamine was also studied. Five volunteers received a single 120-mg oral dose of prenylamine. Urine samples were analyzed using the Abbott TDx immunoassay Amphetamine/Methamphetamine II and using our routine systematic toxicological analysis (STA) gas chromatography-mass spectrometry (GC-MS) procedure. For quantitation purposes, GC-MS was used in the selected-ion monitoring (SIM) mode (ions m/z 118, 122, 240, 244) after solid-phase extraction (Isolute Confirm HCX) and derivatization (heptafluorobutyric anhydride). Amphetamine-d5 was used as internal standard (IS). Chiral separation of the heptafluorobutyrated amphetamine enantiomers was achieved using an Astec Chiraldex G-PN column. The TDx results showed a great variability for the different volunteers. A urine sample of one volunteer showed results as high as 3200 ng/mL, whereas the urine samples of another volunteer never gave results greater than the TDx detection limit (100 ng/mL). Using the STA procedure, the presence of amphetamine could be confirmed in all urine samples with TDx results greater than the cutoff value (300 ng/mL). Using the GC-MS SIM method, amphetamine concentrations up to 1280 ng/mL were determined. Chiral analysis revealed that both enantiomers of amphetamine were present in the samples with a surplus of the S(+)-enantiomer in the early phase of excretion. Forensic implications are discussed.

  6. Single-molecule fluorescence polarization study of conformational change in archaeal group II chaperonin.

    Directory of Open Access Journals (Sweden)

    Ryo Iizuka

    Full Text Available Group II chaperonins found in archaea and in eukaryotic cytosol mediate protein folding without a GroES-like cofactor. The function of the cofactor is substituted by the helical protrusion at the tip of the apical domain, which forms a built-in lid on the central cavity. Although many studies on the change in lid conformation coupled to the binding and hydrolysis of nucleotides have been conducted, the molecular mechanism of lid closure remains poorly understood. Here, we performed a single-molecule polarization modulation to probe the rotation of the helical protrusion of a chaperonin from a hyperthermophilic archaeum, Thermococcus sp. strain KS-1. We detected approximately 35° rotation of the helical protrusion immediately after photorelease of ATP. The result suggests that the conformational change from the open lid to the closed lid state is responsible for the approximately 35° rotation of the helical protrusion.

  7. Solvents effect on the absorption and fluorescence spectra of 7-diethylamino-3-thenoylcoumarin: evaluation and correlation between solvatochromism and solvent polarity parameters.

    Science.gov (United States)

    Basavaraja, Jana; Inamdar, S R; Suresh Kumar, H M

    2015-02-25

    Effect of solvents of varying polarities on absorption and fluorescence spectra and dipole moment of laser dye: 7-diethylamino-3-thenoylcoumarin (DETC) has been investigated. A small band shift is obtained in the absorption spectra compared to emission spectra. The spectral shifts were correlated with Catalan's parameters using linear solvation energy relationship. It reveals that non-specific interaction measured by solvent polarity has more influence on absorption and solvent dipolarity contribution is significant in case of fluorescence. A bathochromic shift observed in absorption and emission spectra with increasing solvent polarity, which implied that the transition involved is π→π(∗). The solvatochromic correlations were used to estimate the excited state dipole moment using experimentally determined ground state dipole moment. The observed single-state excited state dipole moment is found to be greater than the ground state.

  8. Temperature-dependent fluorescence lifetime of a fluorescent polymeric thermometer, poly(N-isopropylacrylamide), labeled by polarity and hydrogen bonding sensitive 4-sulfamoyl-7-aminobenzofurazan.

    Science.gov (United States)

    Gota, Chie; Uchiyama, Seiichi; Yoshihara, Toshitada; Tobita, Seiji; Ohwada, Tomohiko

    2008-03-13

    Fluorescent molecular thermometers showing temperature-dependent fluorescence lifetimes enable thermal mapping of small spaces such as a microchannel and a living cell. We report the temperature-dependent fluorescence lifetimes of poly(NIPAM-co-DBD-AA), which is a random copolymer of N-isopropylacrylamide (NIPAM) and an environment-sensitive fluorescent monomer (DBD-AA) containing a 4-sulfamoyl-7-aminobenzofurazan structure. The average fluorescence lifetime of poly(NIPAM-co-DBD-AA) in aqueous solution increased from 4.22 to 14.1 ns with increasing temperature from 30 to 35 degrees C. This drastic change in fluorescence lifetime (27% increase per 1 degrees C) is the sharpest ever reported. Concentration independency, one of the advantages of fluorescence lifetime measurements, was seen in average fluorescence lifetime (13.7 +/- 0.18 ns) of poly(NIPAM-co-DBD-AA) at 33 degrees C over a wide concentration range (0.005-1 w/v%). With increasing temperature, polyNIPAM units in poly(NIPAM-co-DBD-AA) change their structure from an extended form to a globular form, providing apolar and aprotic environments to the fluorescent DBD-AA units. Consequently, the environment-sensitive DBD-AA units translate the local environmental changes into the extension of the fluorescence lifetime. This role of the DBD-AA units was revealed by a study of solvent effects on fluorescence lifetime of a model environment-sensitive fluorophore.

  9. Comprehensive binary interaction mapping of SH2 domains via fluorescence polarization reveals novel functional diversification of ErbB receptors.

    Directory of Open Access Journals (Sweden)

    Ronald J Hause

    Full Text Available First-generation interaction maps of Src homology 2 (SH2 domains with receptor tyrosine kinase (RTK phosphosites have previously been generated using protein microarray (PM technologies. Here, we developed a large-scale fluorescence polarization (FP methodology that was able to characterize interactions between SH2 domains and ErbB receptor phosphosites with higher fidelity and sensitivity than was previously achieved with PMs. We used the FP assay to query the interaction of synthetic phosphopeptides corresponding to 89 ErbB receptor intracellular tyrosine sites against 93 human SH2 domains and 2 phosphotyrosine binding (PTB domains. From 358,944 polarization measurements, the affinities for 1,405 unique biological interactions were determined, 83% of which are novel. In contrast to data from previous reports, our analyses suggested that ErbB2 was not more promiscuous than the other ErbB receptors. Our results showed that each receptor displays unique preferences in the affinity and location of recruited SH2 domains that may contribute to differences in downstream signaling potential. ErbB1 was enriched versus the other receptors for recruitment of domains from RAS GEFs whereas ErbB2 was enriched for recruitment of domains from tyrosine and phosphatidyl inositol phosphatases. ErbB3, the kinase inactive ErbB receptor family member, was predictably enriched for recruitment of domains from phosphatidyl inositol kinases and surprisingly, was enriched for recruitment of domains from tyrosine kinases, cytoskeletal regulatory proteins, and RHO GEFs but depleted for recruitment of domains from phosphatidyl inositol phosphatases. Many novel interactions were also observed with phosphopeptides corresponding to ErbB receptor tyrosines not previously reported to be phosphorylated by mass spectrometry, suggesting the existence of many biologically relevant RTK sites that may be phosphorylated but below the detection threshold of standard mass spectrometry

  10. 1,1-Dicyano-2-[6-(dimethylamino)naphthalen-2-yl] propene (DDNP): A solvent polarity and viscosity sensitive fluorophore for fluorescence microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Jacobson, A.; Hogenkamp, D.; Barrio, J.R. [UCLA, CA (United States); Petric, A.; Sinur, A. [Univ. of Ljubljana (Slovenia)

    1996-06-19

    1,1-Dicyano-2-[6-(dimethylamino)naphthalen-2-yl] propene (II, DDNP) has been synthesized as a fluorescent dye whose intramolecular rotational relaxation is solvent polarity and viscosity dependent. Its fluorescence emission ({lambda} max: 470-610 nm in hydrophobic and viscous environments) is in a very favorable region for its use with visible fluorescence microscopy, without interference from cell or tissue autofluorescence. Its fluorescence emission quantum yield in an aqueous environment is very low, allowing for facile differentiation between lipid or protein bound state and aqueous media. II crystallizes into two solid isoforms containing one (red crystals) and two conformers (yellow crystals), exhibiting differing spectral properties. X-ray crystal structures reveal a planar arrangement between dimethylamino and naphthalenyl moieties, with out-of-plane arrangements between the malononitrile and naphthalene ring found in each of the three conformers. 41 refs., 9 figs., 2 tabs.

  11. Trimodal color-fluorescence-polarization endoscopy aided by a tumor selective molecular probe accurately detects flat lesions in colitis-associated cancer

    Science.gov (United States)

    Charanya, Tauseef; York, Timothy; Bloch, Sharon; Sudlow, Gail; Liang, Kexian; Garcia, Missael; Akers, Walter J.; Rubin, Deborah; Gruev, Viktor; Achilefu, Samuel

    2014-12-01

    Colitis-associated cancer (CAC) arises from premalignant flat lesions of the colon, which are difficult to detect with current endoscopic screening approaches. We have developed a complementary fluorescence and polarization reporting strategy that combines the unique biochemical and physical properties of dysplasia and cancer for real-time detection of these lesions. Using azoxymethane-dextran sodium sulfate (AOM-DSS) treated mice, which recapitulates human CAC and dysplasia, we show that an octapeptide labeled with a near-infrared (NIR) fluorescent dye selectively identified all precancerous and cancerous lesions. A new thermoresponsive sol-gel formulation allowed topical application of the molecular probe during endoscopy. This method yielded high contrast-to-noise ratios (CNR) between adenomatous tumors (20.6±1.65) and flat lesions (12.1±1.03) and surrounding uninvolved colon tissue versus CNR of inflamed tissues (1.62±0.41). Incorporation of nanowire-filtered polarization imaging into NIR fluorescence endoscopy shows a high depolarization contrast in both adenomatous tumors and flat lesions in CAC, reflecting compromised structural integrity of these tissues. Together, the real-time polarization imaging provides real-time validation of suspicious colon tissue highlighted by molecular fluorescence endoscopy.

  12. Fluorescence Polarization Immunoassay Based on a New Monoclonal Antibody for the Detection of the Zearalenone Class of Mycotoxins in Maize.

    Science.gov (United States)

    Zhang, Xiya; Eremin, Sergei A; Wen, Kai; Yu, Xuezhi; Li, Chenglong; Ke, Yuebin; Jiang, Haiyang; Shen, Jianzhong; Wang, Zhanhui

    2017-03-15

    To develop a sensitive fluorescence polarization immunoassay (FPIA) for screening the zearalenone class of mycotoxins in maize, two new monoclonal antibodies with uniform affinity to the zearalenone class and four fluorescein-labeled tracers were prepared. After careful selection of appropriate tracer-antibody pairs in terms of sensitivity and specificity, a FPIA that could simultaneously detect the zearalenone class with similar sensitivity was developed. Under optimum conditions, the half maximal inhibitory concentrations of the FPIA in buffer were 1.89, 1.97, 2.43, 1.99, 2.27, and 2.44 μg/L for zearalenone, α-zearalenol, β-zearalenol, α-zearalanol, β-zearalanol, and zearalanone, respectively. The limit of detection of FPIA for the zearalenone class was around 12 μg/kg in maize, and the recoveries ranged from 84.6 to 113.8%, with coefficients of variation below 15.3% in spiked samples. Finally, the FPIA was applied for screening naturally contaminated maize samples, and the results indicated a good correlation with that of high-performance liquid chromatography-tandem mass spectrometry.

  13. Reversed-phase liquid chromatography coupled on-line to estrogen receptor bioaffinity detection based on fluorescence polarization.

    Science.gov (United States)

    Reinen, Jelle; Kool, Jeroen; Vermeulen, Nico P E

    2008-04-01

    We describe the development and validation of a high-resolution screening (HRS) platform which couples gradient reversed-phase high-performance liquid chromatography (RP-HPLC) on-line to estrogen receptor alpha (ERalpha) affinity detection using fluorescence polarization (FP). FP, which allows detection at high wavelengths, limits the occurrence of interference from the autofluorescence of test compounds in the bioassay. A fluorescein-labeled estradiol derivative (E2-F) was synthesized and a binding assay was optimized in platereader format. After subsequent optimization in flow-injection analysis (FIA) mode, the optimized parameters were translated to the on-line HRS bioassay. Proof of principle was demonstrated by separating a mixture of five compounds known to be estrogenic (17beta-estradiol, 17alpha-ethinylestradiol and the phytoestrogens coumestrol, coumarol and zearalenone), followed by post-column bioaffinity screening of the individual affinities for ERalpha. Using the HRS-based FP setup, we were able to screen affinities of off-line-generated metabolites of zearalenone for ERalpha. It is concluded that the on-line FP-based bioassay can be used to screen for the affinity of compounds without the disturbing occurrence of autofluorescence.

  14. Electrophoresis of polar fluorescent tracers through the nerve sheath labels neuronal populations for anatomical and functional imaging

    Science.gov (United States)

    Isaacson, Matthew D.; Hedwig, Berthold

    2017-01-01

    The delivery of tracers into populations of neurons is essential to visualize their anatomy and analyze their function. In some model systems genetically-targeted expression of fluorescent proteins is the method of choice; however, these genetic tools are not available for most organisms and alternative labeling methods are very limited. Here we describe a new method for neuronal labelling by electrophoretic dye delivery from a suction electrode directly through the neuronal sheath of nerves and ganglia in insects. Polar tracer molecules were delivered into the locust auditory nerve without destroying its function, simultaneously staining peripheral sensory structures and central axonal projections. Local neuron populations could be labelled directly through the surface of the brain, and in-vivo optical imaging of sound-evoked activity was achieved through the electrophoretic delivery of calcium indicators. The method provides a new tool for studying how stimuli are processed in peripheral and central sensory pathways and is a significant advance for the study of nervous systems in non-model organisms. PMID:28084413

  15. Simultaneous Determination of Fluorescein, Rhodamine 6G and Rhodamine B in Turbid Solution by Polarization Variable-Angle Synchronous Fluorescence Spectrometry

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Polarization variable-angle synchronous fluorescence spectrometry was proposed to determine samples in turbid solution. A mixture of fluorescein, rhodamine 6G and rhodamine B was used to evaluate the technique. The background caused by scattering light was decreased remarkably. The limits of detection were 0.6 ng/ml for fluorescein, 2.3 ng/ml for rhodamine 6G and 4.1 ng/ml for rhodamine B, respectively.

  16. A TiS2 nanosheet enhanced fluorescence polarization biosensor for ultra-sensitive detection of biomolecules

    Science.gov (United States)

    Li, Xiang; Ding, Xuelian; Li, Yongfang; Wang, Linsong; Fan, Jing

    2016-05-01

    Development of new strategies for the sensitive and selective detection of ultra-low concentrations of specific cancer markers is of great importance for assessing cancer therapeutics due to its crucial role in early clinical diagnoses and biomedical applications. In this work, we have developed two types of fluorescence polarization (FP) amplification assay strategies for the detection of biomolecules by using TiS2 as a FP enhancer and Zn2+-dependent self-hydrolyzing deoxyribozymes as catalysts to realize enzyme-catalyzed target-recycling signal amplification. One approach is based on the terminal protection of small-molecule-linked DNA, in which biomolecular binding to small molecules in DNA-small-molecule chimeras can protect the conjugated DNA from degradation by exonuclease I (Exo I); the other approach is based on the terminal protection of biomolecular bound aptamer DNA, in which biomolecules directly bound to the single strand aptamer DNA can protect the ssDNA from degradation by Exo I. We select folate receptor (FR) and thrombin (Tb) as model analytes to verify the current concept. It is shown that under optimized conditions, our strategies exhibit high sensitivity and selectivity for the quantification of FR and Tb with low detection limits (0.003 ng mL-1 and 0.01 pM, respectively). Additionally, this strategy is a simple ``mix and detect'' approach, and does not require any separation steps. This biosensor is also utilized in the analysis of real biological samples, the results agree well with those obtained by the enzyme-linked immunosorbent assay (ELISA).Development of new strategies for the sensitive and selective detection of ultra-low concentrations of specific cancer markers is of great importance for assessing cancer therapeutics due to its crucial role in early clinical diagnoses and biomedical applications. In this work, we have developed two types of fluorescence polarization (FP) amplification assay strategies for the detection of biomolecules

  17. [Fluorescence polarization used to investigate the cell membrane fluidity of Saccharomyces cerevisiae treated by pulsed electric field].

    Science.gov (United States)

    Zhang, Ying; Zeng, Xin-An; Wen, Qi-Biao; Li, Lin

    2008-01-01

    To know the lethal mechanism of microorganisms under pulsed electric field treatment, the relationship between the inactivation of Saccharomyces cerevisiae (CICC1308) cell and the permeability and fluidity changes of its cell membrane treated by pulsed electric field (0-25 kV x cm(-1), 0-266 ms) was investigated. With 1,6-diphenyl-1,3,5-hexatriene (DPH) used as a probe, the cell membrane fluidity of Saccharomyces cerevisiae treated by pulsed electric field was expressed by fluorescence polarization. Results showed that the cell membrane fluidity decreases when the electric flied strength is up to 5 kV x cm(-1), and decreases with the increase in electric field strength and treatment time. The plate counting method and ultraviolet spectrophotometer were used to determine the cell viability and to investigate the cell membrane permeability, respectively, treated by pulsed electric field. Results showed that the lethal ratio and the content of protein and nucleic acid leaked from intracellular plasma increased with the increase in the electric field strength and the extension of treatment time. Even in a quite lower electric field of 5 kV x cm(-1) with a tiny microorganism lethal level, the increase in UV absorption value and the decrease in fluidity were significant. It was demonstrated that the cell membrane fluidity decreases with the increase in lethal ratio and cell membrane permeability. The viscosity of cell membrane increases with the decrease in fluidity. These phenomena indicated that cell membrane is one of the most key sites during the pulsed electric field treatment, and the increased membrane permeability and the decreased cell membrane fluidity contribute to the cell death.

  18. Analysis of local structure of Arg10 domain in apo-α- lactalbumin with a polarity-sensitive arginine-specific fluorescent probe

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The polarity-sensitive fluorescent probe, 3-(4-chloro-6-p-glyoxalphenoxy-1,3,5-triazinylamino)-7- (dimethylamino)-2-methylphenazine, was used to analyze the local structure of apo-α-lactalbumin by detecting the polarity and conformational changes of the arginine residue (Arg10) domain. The polarity of the Arg10 domain in both native and heat-denatured apo-α-lactalbumin was determined, which corresponds to a dielectric constant of 16, and the hydrophobic core near the Arg10 was found to be conservative for heating. Meanwhile, the effect of Ca2+ binding on the conformational changes of the Arg10 domain was studied, revealing that the hydrophobic core near the Arg10 is insensitive to the binding of Ca2+.

  19. Comparison of fluorescence polarization assay with Rose Bengal (RB test and complement fixation tests for the diagnosis of buffalo (Bubalus bubalis brucellosis in a high-prevalence area

    Directory of Open Access Journals (Sweden)

    G. Iovane

    2010-02-01

    Full Text Available The fluorescence polarisation assay (FPA was evaluated for the serological diagnosis of bovine brucellosis in buffalo (Bubalus Bubalis in southern Italy. This assay uses O-polysaccharide prepared from Brucella Abortus lipopolysaccharide conjugated with fluorescein isothiocyanate as a tracer. It has many methodological advantages over older, more established tests and can be performed in short time. To measure the fluorescence polarization, a Tecan GENios Pro (Prionics fluorescence-polarization analyzer was used with the procedure described by Nielsen et al. 1996. A cut-off value of 117 millipolarization (mP units was used for testing 912 buffalo sera from Campania Region (526 positive sera and 386 negative sera according to the complement fixation test; CFT. All samples were tested with the Rose Bengal plate (RB. Sensitivity and specificity (Sn for RB were 84.0% and 87.8% and for FPA were 92.6% and 88.9 percent. The FPA gave a kappa coefficient of agreement with respect to CFT of 0.755, while RB (relative to the CFT gave coefficients of 0,715. Finally, ROC analysis suggested a cut-off value which did not agree with the one recommended in the test procedure for cow.

  20. Investigation of the Stability of the Ruthenium based Dye (N719) Utilizing the Polarization Properties of Dispersive Raman Modes and/or of the Fluorescent Emission

    DEFF Research Database (Denmark)

    Hassing, Søren; Jernshøj, Kit Drescher; Phuong, Nguyen

    2013-01-01

    Dye-sensitized solar cells (DSCs) offer intriguing new possibilities with the integration of these into, e.g., power generating windows or facade applications. For the DSCs to constitute a viable investment, the thermal appliance with respect to the working conditions typically encountered must...... be considered. One of the aspects governing the long-term thermal stability of the DSC is the dye stability and hence whether or not the dye is degraded upon heating or illumination. This emphasizes the need for a sensitive and nondestructive measuring technique with which it is possible to distinguish between...... for short) is possible by exploiting a combination of the polarization properties of the dispersive Raman modes with the small spectral change in the visible absorption spectrum and/or the difference in the polarization of the fluorescence related to the difference in molecular configuration. By measuring...

  1. Tip-enhanced fluorescence with radially polarized illumination for monitoring loop-mediated isothermal amplification on Hepatitis C virus cDNA

    Science.gov (United States)

    Wei, Shih-Chung; Chuang, Tsung-Liang; Wang, Da-Shin; Lu, Hui-Hsin; Gu, Frank X.; Sung, Kung-Bin; Lin, Chii-Wann

    2015-02-01

    A tip nanobiosensor for monitoring DNA replication was presented. The effects of excitation power and polarization on tip-enhanced fluorescence (TEF) were assessed with the tip immersed in fluorescein isothiocyanate solution first. The photon count rose on average fivefold with radially polarized illumination at 50 mW. We then used polymerase-functionalized tips for monitoring loop-mediated isothermal amplification on Hepatitis C virus cDNA. The amplicon-SYBR Green I complex was detected and compared to real-time loop-mediated isothermal amplification. The signals of the reaction using 4 and 0.004 ng/μl templates were detected 10 and 30 min earlier, respectively. The results showed the potential of TEF in developing a nanobiosensor for real-time DNA amplification.

  2. A fluorescence polarization assay to quantify biotin and biotin-binding proteins in whole plant extracts using Alexa-Fluor 594 biocytin.

    Science.gov (United States)

    Martin, Harry; Murray, Colleen; Christeller, John; McGhie, Tony

    2008-10-01

    A high-throughput fluorescence polarization assay has been developed for the detection of biotin and biotin-binding proteins in whole leaf extracts. Various groups are investigating the insecticidal properties of avidin and other biotin-binding proteins expressed in leaves of transgenic plants. The methods commonly used to quantify biotin and avidin in leaf extracts are enzyme-linked immunosorbent assay (ELISA) and Western blotting. Here we describe a homogeneous fluorescence polarization (FP) method that quantifies transgenic avidin in whole leaf extract by the simple addition of the fluorescent avidin ligand Alexa-Fluor 594 biocytin (AFB). The FP assay exploits the fact that AFB excites and emits in regions of the spectrum that are relatively free of background fluorescence in leaf extract. Transgenic leaf avidin can be quantified within 1-2 h by the FP method, in comparison with 1-2 days for ELISA and Western blotting. The FP method can also measure the amount of biotin in control leaves, not expressing avidin. Functional avidin levels of 1.54 microM (26.1 microg/g leaf tissue) were detected in tobacco leaves expressing vacuole-targeted avidin. Control leaves had biotin levels of around 0.74 microM (approximately 0.18 microg/g leaf tissue). Reagent costs are minimal: typically AFB is used at concentrations of 1-10 nM, avidin is used at 1-100 nM, and sample volumes are 20 microL in 384-well microplates.

  3. High-throughput screening for small-molecule inhibitors of LARG-stimulated RhoA nucleotide binding via a novel fluorescence polarization assay.

    Science.gov (United States)

    Evelyn, Chris R; Ferng, Timothy; Rojas, Rafael J; Larsen, Martha J; Sondek, John; Neubig, Richard R

    2009-02-01

    Guanine nucleotide exchange factors (GEFs) stimulate guanine nucleotide exchange and the subsequent activation of Rho-family proteins in response to extracellular stimuli acting upon cytokine, tyrosine kinase, adhesion, integrin, and G-protein-coupled receptors (GPCRs). Upon Rho activation, several downstream events occur, such as morphological and cytoskeletal changes, motility, growth, survival, and gene transcription. The leukemia-associated RhoGEF (LARG) is a member of the regulators of G-protein signaling homology domain (RH) family of GEFs originally identified as a result of chromosomal translocation in acute myeloid leukemia. Using a novel fluorescence polarization guanine nucleotide-binding assay using BODIPY-Texas Red-GTPgammaS (BODIPY-TR-GTPgammaS), the authors performed a 10,000-compound high-throughput screen for inhibitors of LARG-stimulated RhoA nucleotide binding. Five compounds identified from the high-throughput screen were confirmed in a nonfluorescent radioactive guanine nucleotide-binding assay measuring LARG-stimulated [( 35)S] GTPgammaS binding to RhoA, thus ruling out nonspecific fluorescent effects. All 5 compounds selectively inhibited LARG-stimulated RhoA [( 35)S] GTPgammaS binding but had little to no effect on RhoA or Galpha( o) [(35)S] GTPgammaS binding. Therefore, these 5 compounds should serve as promising starting points for the development of small-molecule inhibitors of LARG-mediated nucleotide exchange as both pharmacological tools and therapeutics. In addition, the fluorescence polarization guanine nucleotide-binding assay described here should serve as a useful approach for both high-throughput screening and general biological applications.

  4. An investigation into the role of macromolecules of different polarity as passivating agent on the physical, chemical and structural properties of fluorescent carbon nanodots

    Science.gov (United States)

    Alas, Melis Ozge; Genc, Rukan

    2017-05-01

    In this study, comparative evaluation of fluorescent carbon nanodots (C-Dots) prepared using carob molasses was reported by screening various biocompatible macromolecules as passivating agent (PA). Incorporation of PAs with different molecular weight, polarity, and chemical structure was examined, and compared with the polyethylene glycol (PEG, Mn = 10 kN) passivated and pristine C-Dots. Not only the fluorescence properties but also many other features including size, crystal structure, colloidal conductivity, resistance to photobleaching, quantum yield, and UV-modulated surface interaction of them with the reactive oxygen species (ROS) as well as ROS production were investigated. Photoluminescence (PL) capacity of C-Dots was found to be associated with the number of surface alkyl groups and polymeric hydrogen bounding present on the C-Dot surface (increased number is associated with decreased PL) while surface conductivity of C-Dots in water was proportional to the PL intensity. More importantly, C-Dots with relatively poorer fluorescent were investigated in various organic solvents (hexane, methanol, acetone, ethanol, dimethylformamide (DMF), and DMSO). As happens with the fluorescent dyes, their PL intensities were significantly enhanced (even for pristine C-Dots) depending on the solvent characteristics. All of the C-Dots synthesized were further evaluated by means of UV-induced generation of ROS and inhibition of ROS by using H2O2 as model. In contrary to other carbonaceous nanomaterials, they did not show any ROS generation, on the contrary, they showed ROS scavenging activity that can be modulated by UV-irradiation ( λ exc = 365 nm). PEG and alginate passivated C-Dots inhibited H2O2 activity at LC50 values below 10 mg/mL.

  5. Novel Alexa Fluor-488 labeled antagonist of the A(2A) adenosine receptor: Application to a fluorescence polarization-based receptor binding assay.

    Science.gov (United States)

    Kecskés, Miklós; Kumar, T Santhosh; Yoo, Lena; Gao, Zhan-Guo; Jacobson, Kenneth A

    2010-08-15

    Fluorescence polarization (FP) assay has many advantages over the traditional radioreceptor binding studies. We developed an A(2A) adenosine receptor (AR) FP assay using a newly synthesized fluorescent antagonist of the A(2A)AR (MRS5346), a pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-amine derivative conjugated to the fluorescent dye Alexa Fluor-488. MRS5346 displayed a K(i) value of 111+/-16nM in radioligand binding using [(3)H]CGS21680 and membranes prepared from HEK293 cells stably expressing the human A(2A)AR. In a cyclic AMP functional assay, MRS5346 was shown to be an A(2A)AR antagonist. MRS5346 did not show any effect on A(1) and A(3) ARs in binding or the A(2B)AR in a cyclic AMP assay at 10microM. Its suitability as a fluorescent tracer was indicated in an initial observation of an FP signal following A(2A)AR binding. The FP signal was optimal with 20nM MRS5346 and 150microg protein/mL HEK293 membranes. The association and dissociation kinetic parameters were readily determined using this FP assay. The K(d) value of MRS5346 calculated from kinetic parameters was 16.5+/-4.7nM. In FP competition binding experiments using MRS5346 as a tracer, K(i) values of known AR agonists and antagonists consistently agreed with K(i) values from radioligand binding. Thus, this FP assay, which eliminates using radioisotopes, appears to be appropriate for both routine receptor binding and high-throughput screening with respect to speed of analysis, displaceable signal and precision. The approach used in the present study could be generally applicable to other GPCRs.

  6. Alignment of Solutes in Stretched Polyethylene. Determination of the Five Second and Fourth Moments of the Orientation Distribution of 2-Fluoropyrene from Polarized Fluorescence

    DEFF Research Database (Denmark)

    Langkilde, Frans W.; Gisin, Markus; Thulstrup, Erik W.;

    1983-01-01

    Measurements of linear dichroism and of polarized fluorescence of 2-fluoropyrene (2-F-1) in stretched linear low-density polyethylene (LLDPE) at 77K have been used to evaluate the two independent second moments, 〈cos2 z〉 and 〈cos2 y〉, as well as the three independent fourth moments, 〈cos4 z〉, 〈cos4...... y〉, and 〈cos4 x〉, of the orientation distribution function. The results are used to discuss two previously proposed detailed models for the mechanism of the orientation of aromatics in stretched polyethylene. For pyrene (1) and 2-methylpyrene (2-Me-1), four of the five moments were obtained...... axis in the two compounds, respectively. This behavior is ascribed to a symmetry-lowering perturbation by the environment, related to the Ham effect....

  7. Portable ultrahigh-vacuum sample storage system for polarization-dependent total-reflection fluorescence x-ray absorption fine structure spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Yoshihide, E-mail: e0827@mosk.tytlabs.co.jp; Nishimura, Yusaku F.; Suzuki, Ryo; Beniya, Atsushi; Isomura, Noritake [Toyota Central R& D Labs., Inc., Yokomichi 41-1, Nagakute, Aichi 480-1192 (Japan); Uehara, Hiromitsu; Asakura, Kiyotaka; Takakusagi, Satoru [Catalysis Research Center, Hokkaido University, Kita 21-10, Sapporo, Hokkaido 001-0021 (Japan); Nimura, Tomoyuki [AVC Co., Ltd., Inada 1450-6, Hitachinaka, Ibaraki 312-0061 (Japan)

    2016-03-15

    A portable ultrahigh-vacuum sample storage system was designed and built to investigate the detailed geometric structures of mass-selected metal clusters on oxide substrates by polarization-dependent total-reflection fluorescence x-ray absorption fine structure spectroscopy (PTRF-XAFS). This ultrahigh-vacuum (UHV) sample storage system provides the handover of samples between two different sample manipulating systems. The sample storage system is adaptable for public transportation, facilitating experiments using air-sensitive samples in synchrotron radiation or other quantum beam facilities. The samples were transferred by the developed portable UHV transfer system via a public transportation at a distance over 400 km. The performance of the transfer system was demonstrated by a successful PTRF-XAFS study of Pt{sub 4} clusters deposited on a TiO{sub 2}(110) surface.

  8. Alignment of Ar{sup +} [{sup 3}P]4p{sup 2}P{sup 0}{sub 3/2} satellite state from the polarization analysis of fluorescent radiation after photoionization

    Energy Technology Data Exchange (ETDEWEB)

    Yenen, O.; McLaughlin, K.W.; Jaecks, D.H. [Univ. of Nebraska, Lincoln, NE (United States)] [and others

    1997-04-01

    The measurement of the polarization of radiation from satellite states of Ar{sup +} formed after the photoionization of Ar provides detailed information about the nature of doubly excited states, magnetic sublevel cross sections and partial wave ratios of the photo-ejected electrons. Since the formation of these satellite states is a weak process, it is necessary to use a high flux beam of incoming photons. In addition, in order to resolve the many narrow doubly excited Ar resonances, the incoming photons must have a high resolution. The characteristics of the beam line 9.0.1 of the Advanced Light Source fulfill these requirements. The authors determined the polarization of 4765 {Angstrom} fluorescence from the Ar{sup +} [{sup 3}P] 4p {sup 2}P{sub 3/2}{sup 0} satellite state formed after photoionization of Ar by photons from the 9.0.1 beam line of ALS in the 35.620-38.261 eV energy range using a resolution of approximately 12,700. This is accomplished by measuring the intensities of the fluorescent light polarized parallel (I{parallel}) and perpendicular (I{perpendicular}) to the polarization axis of the incident synchrotron radiation using a Sterling Optics 105MB polarizing filter. The optical system placed at 90{degrees} with respect to the polarization axis of the incident light had a narrow band interference filter ({delta}{lambda}=0.3 nm) to isolate the fluorescent radiation.

  9. Use of the Brucella melitensis native hapten to diagnose brucellosis in goats by a rapid, simple, and specific fluorescence polarization assay.

    Science.gov (United States)

    Ramírez-Pfeiffer, Carlos; Díaz-Aparicio, Efrén; Gomez-Flores, Ricardo; Rodríguez-Padilla, Cristina; Morales-Loredo, Alberto; Alvarez-Ojeda, Genoveva

    2008-06-01

    The performance of the fluorescence polarization assay (FPA) using the recently described Brucella melitensis native hapten and the Brucella abortus O-polysaccharide tracer was evaluated and compared with those of The World Organization for Animal Health tests related to indirect and competitive enzyme-linked immunosorbent assays as classification variables for goat sera obtained from a high-prevalence area where vaccination was performed; test series were also evaluated to increase the final specificity of the tests. Our results showed that the respective relative sensitivity and specificity were 99.7% and 32.5% for the rose Bengal test with a 3% cell concentration (RBT3), 92.8% and 68.8% for the rose Bengal test with 8% cell concentration (RBT8), 98.4% and 84.9% for the Canadian complement fixation test (CFT), 83.7% and 65.5% for the Mexican CFT, 98.4% and 81.0% for the buffered plate agglutination test (BPAT), and 78.1% and 89.3% for the fluorescence polarization assay (FPA). The use of the FPA as the secondary test significantly increased the final specificities of test combinations; the screening tests BPAT, RBT3, and RBT8 plus FPA resulted in 90%, 91.2%, and 91.3% final specificities, respectively, whereas for the combinations RBT3 plus Mexican CFT, RBT8 plus Mexican CFT, and BPAT plus Canadian CFT, the specificities were 65.5%, 63.2%, and 91.7%, respectively. The results suggested that the FPA may be routinely applied as an adaptable screening test for diagnosis of goat brucellosis, since its cutoff can be adjusted to improve its sensitivity or specificity, it is a rapid and simple test, it can be the test of choice when specificity is relevant or when an alternative confirmatory test is not available, and it is not affected by vaccination, thus reducing the number of goats wrongly slaughtered due to misdiagnosis.

  10. Effects of solvent polarity on the absorption and fluorescence spectra of chlorogenic acid and caffeic acid compounds: determination of the dipole moments.

    Science.gov (United States)

    Belay, Abebe; Libnedengel, Ermias; Kim, Hyung Kook; Hwang, Yoon-Hwae

    2016-02-01

    The effects of solvent polarity on absorption and fluorescence spectra of biologically active compounds (chlorogenic acid (CGA) and caffeic acids (CA)) have been investigated. In both spectra pronounced solvatochromic effects were observed with shift of emission peaks larger than the corresponding UV-vis electronic absorption spectra. From solvatochromic theory the ground and excited-state dipole moments were determined experimentally and theoretically. The differences between the excited and ground state dipole moment determined by Bakhshiev, Kawski-Chamma-Viallet and Reichardt equations are quite similar. The ground and excited-state dipole moments were determined by theoretical quantum chemical calculation using density function theory (DFT) method (Gaussian 09) and were also similar to the experimental results. The HOMO-LUMO energy band gaps for CGA and CFA were calculated and found to be 4.1119 and 1.8732 eV respectively. The results also indicated the CGA molecule is more stable than that of CFA. It was also observed that in both compounds the excited state possesses a higher dipole moment than that of the ground state. This confirms that the excited state of the hydroxycinnamic compounds is more polarized than that of the ground state and therefore is more sensitive to the solvent.

  11. A fluorescence polarization based screening assay for identification of small molecule inhibitors of the PICK1 PDZ domain

    DEFF Research Database (Denmark)

    Thorsen, Thor S; Madsen, Kenneth L; Dyhring, Tino

    2011-01-01

    domain in PICK1 (protein interacting with C kinase 1). We screened 43,380 compounds for their ability to inhibit binding of an Oregon Green labeled C-terminal dopamine transporter peptide (OrG-DAT C13) to purified PICK1 in solution. The assay was highly reliable with excellent screening assay parameters...... (Z'˜0.7 and Z˜0.6). Out of ~200 compounds that reduced FP to less than 80% of the control wells, six compounds were further characterized. The apparent affinities of the compounds were determined in FP competition binding experiments and ranged from ~5.0 µM to ~193 µM. Binding to the PICK1 PDZ domain...... was confirmed for five of the compounds (CSC-03, CSC-04, CSC-43, FSC-231 and FSC-240) in a non-fluorescence based assay by their ability to inhibit pull-down of PICK1 by a C-terminal DAT GST fusion protein. CSC-03 displayed the highest apparent affinity (5.0 µM) in the FP assay, and was according...

  12. Fluorescence polarization measures energy funneling in single light-harvesting antennas--LH2 vs conjugated polymers.

    Science.gov (United States)

    Camacho, Rafael; Tubasum, Sumera; Southall, June; Cogdell, Richard J; Sforazzini, Giuseppe; Anderson, Harry L; Pullerits, Tõnu; Scheblykin, Ivan G

    2015-10-19

    Numerous approaches have been proposed to mimic natural photosynthesis using artificial antenna systems, such as conjugated polymers (CPs), dendrimers, and J-aggregates. As a result, there is a need to characterize and compare the excitation energy transfer (EET) properties of various natural and artificial antennas. Here we experimentally show that EET in single antennas can be characterized by 2D polarization imaging using the single funnel approximation. This methodology addresses the ability of an individual antenna to transfer its absorbed energy towards a single pool of emissive states, using a single parameter called energy funneling efficiency (ε). We studied individual peripheral antennas of purple bacteria (LH2) and single CP chains of 20 nm length. As expected from a perfect antenna, LH2s showed funneling efficiencies close to unity. In contrast, CPs showed lower average funneling efficiencies, greatly varying from molecule to molecule. Cyclodextrin insulation of the conjugated backbone improves EET, increasing the fraction of CPs possessing ε = 1. Comparison between LH2s and CPs shows the importance of the protection systems and the protein scaffold of LH2, which keep the chromophores in functional form and at such geometrical arrangement that ensures excellent EET.

  13. Fluorescence polarization measures energy funneling in single light-harvesting antennas—LH2 vs conjugated polymers

    Science.gov (United States)

    Camacho, Rafael; Tubasum, Sumera; Southall, June; Cogdell, Richard J.; Sforazzini, Giuseppe; Anderson, Harry L.; Pullerits, Tõnu; Scheblykin, Ivan G.

    2015-01-01

    Numerous approaches have been proposed to mimic natural photosynthesis using artificial antenna systems, such as conjugated polymers (CPs), dendrimers, and J-aggregates. As a result, there is a need to characterize and compare the excitation energy transfer (EET) properties of various natural and artificial antennas. Here we experimentally show that EET in single antennas can be characterized by 2D polarization imaging using the single funnel approximation. This methodology addresses the ability of an individual antenna to transfer its absorbed energy towards a single pool of emissive states, using a single parameter called energy funneling efficiency (ε). We studied individual peripheral antennas of purple bacteria (LH2) and single CP chains of 20 nm length. As expected from a perfect antenna, LH2s showed funneling efficiencies close to unity. In contrast, CPs showed lower average funneling efficiencies, greatly varying from molecule to molecule. Cyclodextrin insulation of the conjugated backbone improves EET, increasing the fraction of CPs possessing ε = 1. Comparison between LH2s and CPs shows the importance of the protection systems and the protein scaffold of LH2, which keep the chromophores in functional form and at such geometrical arrangement that ensures excellent EET. PMID:26478272

  14. 异丙醇-水配合液的荧光偏振和时间分辨特性%Fluorescence Polarization and Time Resolved Characteristics of Isopropanol-water Mixture

    Institute of Scientific and Technical Information of China (English)

    韩彩芹; 段培同; 吴斌; 刘莹; 骆晓森; 倪晓武

    2011-01-01

    The polarization fluorescence spectra of isopropanol-water mixture excited by ultraviolet light was studied experimentally. The decay process of fluorescence intensity was detected at different center emission peaks. The curve was fitted by an exponential function and the processing data was obtained by deconvolution. Both the polarization degree and fluorescence lifetime were calculated, and mathematical characterization was performed for the fluorescence counts decay curves. The fluorescence emission and polarization characteristics were discussed. It is found that the isopropanol-water mixture excited by ultraviolet light obtains partially polarized fluorescence with certain molecular orientation. The polarization degree and anisotropy degree are 0.542 and 0.441, respectively. Induced by exciting light with wavelengths of 220 nm and 232 nm, the fluorescence lifetime of isopropanol-water mixture at peaks of 277, 284, 293,309 nm is about 17 ns. While the average fluorescence lifetime at peaks of 328 nm, 345 nm and 362 nm is around 21, 22, 16 ns, respectively. It is related with the molecular cluster structure relative stability of isopropanol-water mixture by the action of hydrogen bond. The research will contribute to the study of the molecular characteristic of isopropanol-water cluster.%研究了紫外光照射下异丙醇-水配合液的偏振荧光光谱,以及不同荧光峰处光子强度随时间的衰变过程,计算了偏振度并讨论了其偏振特性,测试了不同峰位对应的荧光寿命并分析了其荧光发射特性.结果表明,异丙醇-水配合液在紫外光激励下发射的荧光为具有确定分子取向的部分偏振光,偏振度和各向异性度分别为0.542和0.441.在波长为220 nm和232 nm的激发光照射下,荧光峰位于277,284,293,309 nm,对应寿命均约为17 ns.而328,345,362 nm荧光峰对应的平均寿命分别约为21,22,16 ns,这与氢键作用下异丙醇和水形成团簇结构的相对稳定性有关.

  15. Tungsten disulfide nanosheet and exonuclease III co-assisted amplification strategy for highly sensitive fluorescence polarization detection of DNA glycosylase activity

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jingjin; Ma, Yefei [Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources of Education Ministry, Guangxi Normal University, Guilin, 541004 (China); Kong, Rongmei [The Key Laboratory of Life-Organic Analysis, College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu, Shandong 273165 (China); Zhang, Liangliang, E-mail: liangzhang319@163.com [Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources of Education Ministry, Guangxi Normal University, Guilin, 541004 (China); Yang, Wen; Zhao, Shulin [Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources of Education Ministry, Guangxi Normal University, Guilin, 541004 (China)

    2015-08-05

    Herein, we introduced a tungsten disulfide (WS{sub 2}) nanosheet and exonuclease III (Exo III) co-assisted signal amplification strategy for highly sensitive fluorescent polarization (FP) assay of DNA glycosylase activity. Two DNA glycosylases, uracil-DNA glycosylase (UDG) and human 8-oxoG DNA glycosylase 1 (hOGG1), were tested. A hairpin-structured probe (HP) which contained damaged bases in the stem was used as the substrate. The removal of damaged bases from substrate by DNA glycosylase would lower the melting temperature of HP. The HP was then opened and hybridized with a FAM dye-labeled single strand DNA (DP), generating a duplex with a recessed 3′-terminal of DP. This design facilitated the Exo III-assisted amplification by repeating the hybridization and digestion of DP, liberating numerous FAM fluorophores which could not be adsorbed on WS{sub 2} nanosheet. Thus, the final system exhibited a small FP signal. However, in the absence of DNA glycosylases, no hybridization between DP and HP was occurred, hampering the hydrolysis of DP by Exo III. The intact DP was then adsorbed on the surface of WS{sub 2} nanosheet that greatly amplified the mass of the labeled-FAM fluorophore, resulting in a large FP value. With the co-assisted amplification strategy, the sensitivity was substantially improved. In addition, this method was applied to detect UDG activity in cell extracts. The study of the inhibition of UDG was also performed. Furthermore, this method is simple in design, easy in implementation, and selective, which holds potential applications in the DNA glycosylase related mechanism research and molecular diagnostics. - Highlights: • A fluorescence polarization strategy for DNA glycosylase activity detection was developed. • The present method was based on WS{sub 2} nanosheet and exonuclease III co-assisted signal amplification. • A high sensitivity and desirable selectivity were achieved. • This method provides a promising universal platform for DNA

  16. Detection of anatoxin-a and three analogs in Anabaena spp. cultures: new fluorescence polarization assay and toxin profile by LC-MS/MS.

    Science.gov (United States)

    Sanchez, Jon A; Otero, Paz; Alfonso, Amparo; Ramos, Vitor; Vasconcelos, Vitor; Aráoz, Romulo; Molgó, Jordi; Vieytes, Mercedes R; Botana, Luis M

    2014-01-24

    Anatoxin-a (ATX) is a potent neurotoxin produced by several species of Anabaena spp. Cyanobacteria blooms around the world have been increasing in recent years; therefore, it is urgent to develop sensitive techniques that unequivocally confirm the presence of these toxins in fresh water and cyanobacterial samples. In addition, the identification of different ATX analogues is essential to later determine its toxicity. In this paper we designed a fluorescent polarization (FP) method to detect ATXs in water samples. A nicotinic acetylcholine receptor (nAChR) labeled with a fluorescein derivative was used to develop this assay. Data showed a direct relationship between the amount of toxin in a sample and the changes in the polarization degree of the emitted light by the labeled nAChR, indicating an interaction between the two molecules. This method was used to measure the amount of ATX in three Anabaena spp. cultures. Results indicate that it is a good method to show ATXs presence in algal samples. In order to check the toxin profile of Anabaena cultures a LC-MS/MS method was also developed. Within this new method, ATX-a, retention time (RT) 5 min, and three other molecules with a mass m/z 180.1 eluting at 4.14 min, 5.90 min and 7.14 min with MS/MS spectra characteristic of ATX toxin group not previously identified were detected in the Anabaena spp. cultures. These ATX analogues may have an important role in the toxicity of the sample.

  17. Effectiveness of Rose Bengal test and fluorescence polarization assay in the diagnosis of Brucella spp. infections in free range cattle reared in endemic areas in Zambia.

    Science.gov (United States)

    Muma, J B; Lund, A; Nielsen, K; Matope, G; Munyeme, M; Mwacalimba, K; Skjerve, E

    2009-06-01

    The effectiveness of Rose Bengal test (RBT) and fluorescence polarization assay (FPA) in diagnosing cattle brucellosis in endemic areas was assessed and RBT and FPA test agreement was compared (n = 319). The sensitivity of RBT and FPA in detecting low Brucella titres were evaluated in paired sera (n = 34). A logistic regression model was constructed to predict cattle test result in FPA using RBT as the main predictor and incorporating bio-data and animal history. There was 79.3% agreement between the RBT and FPA (Kappa = 0.59; Std error = 0.05; p = 0.000) and a high correspondence between high RBT scores and positive FPA results suggesting that sera with high RBT score may not require confirmation with tests such as competitive-ELISA or CFT. High FPA cut-off points were more likely to miss animals with low antibody titres. The RBT had a reduced ability in detecting low antibody titres compared to the FPA. FPA test interpretation was improved if a priori information, such as sex and age was used. Under the challenging disease surveillance conditions prevailing in rural Africa, field-testing methods that are sensitive and specific; allow single animal contact, low technical skills in data interpretation are suitable.

  18. Toxicological detection of the designer drug 3,4-methylenedioxyethylamphetamine (MDE, "Eve") and its metabolites in urine by gas chromatography-mass spectrometry and fluorescence polarization immunoassay.

    Science.gov (United States)

    Ensslin, H K; Kovar, K A; Maurer, H H

    1996-08-30

    Studies are presented on the toxicological detection of the designer drug methylenedioxyethylamphetamine [MDE, rac-N-ethyl-(3,4-methylenedioxyphenyl)-propane-2-amine] in urine after a single oral dose of 140 mg of MDE by GC-MS and fluorescence polarization immunoassay (FPIA). After acid hydrolysis, extraction and acetylation MDE and its metabolites could be detected by mass chromatography with the selected ions m/z 72, 86, 114, 150, 162 and 164, followed by identification of the peaks underlying full mass spectra by computer library search. The following metabolites could be detected: unchanged MDE and 3,4-dihydroxyethylamphetamine (DHE) for 33-62 h, 3,4-methylenedioxyamphetamine (MDA) for 32-36 h and 4-hydroxy-3-methoxyethylamphetamine (HME) for 7-8 days. 3,4-Dihydroxyamphetamine (DHA), 4-hydroxy-3-methoxyamphetamine (HMA), piperonyl acetone, 3,4-dihydroxyphenyl acetone and 4-hydroxy-3-methoxyphenyl acetone could only be detected in trace amounts within the first few hours. The Abbott TD x FPIA assay amphetamine/metamphetamine II gave positive results in urine for 33-62 h. Therefore, positive immunoassay results could be confirmed by the GC-MS procedure which also allowed the differentiation of MDE and its homologues 3,4-methylenedioxymethamphetamine (MDMA) and MDA as well as other amphetamine derivatives interfering with the TD x assay. Furthermore, this GC-MS procedure allowed the simultaneous detection of most of the toxicologically relevant drugs.

  19. Improved performance of Brucella melitensis native hapten over Brucella abortus OPS tracer on goat antibody detection by the fluorescence polarization assay.

    Science.gov (United States)

    Ramírez-Pfeiffer, C; Díaz-Aparicio, E; Rodríguez-Padilla, C; Morales-Loredo, A; Alvarez-Ojeda, G; Gomez-Flores, R

    2008-06-15

    The current method for goat brucellosis diagnosis is based on the World Organization for Animal Health (OIE) using the screening card test (CT), with antigen at 8% (CT8) or 3% (CT3) of cell concentrations, and the confirmatory complement fixation test (CFT). However, these tests do not differentiate antibodies induced by vaccination from those derived from field infections by Brucella species or other bacterial agents; in places like Mexico, where the prevalence of brucellosis and the vaccination rates are high, there is a considerable percentage of false positive reactions that causes significant unnecessary slaughter of animals. Furthermore, results of the fluorescence polarization assay (FPA) using the Brucella abortus O-polysaccharide (OPS) tracer in goats are poorer than those with cattle. The present study was undertaken to investigate a tracer prepared from the native hapten (NH) of the Rev. 1 strain of Brucella melitensis to improve FPA performance on goat brucellosis diagnosis. Evaluation of 48 positive samples and 96 negative samples showed that the NH tracer was more accurate (pgoat sera samples selected by test series approved by the OIE (card test 3% and CFT). We demonstrated a new application for the NH lipopolysaccharide on detecting antibodies against Brucella using the FPA, which may yield faster results (minutes vs. 24-72h) than the immunodiagnosis assays frequently used in bovine brucellosis. In addition, NH tracer produces similar or better performance results than the conventional OPS tracer, using the FPA in goat sera samples.

  20. Polarized fluorescent emission in uniaxial liquid crystals. The effect of intramolecular energy transfer and rotational Brownian motion on measurements of the orientational distribution function

    DEFF Research Database (Denmark)

    Chapoy, Larry Lawrence; DuPré, Donald B.

    1978-01-01

    An expression is derived for the anisotropic fluorescent emission in uniaxial liquid crystals where fluorescent sites governed by an initial nonrandom distribution of orientations are subject to rotational Brownian motion. The possibility of nonparallelism of absorption and emission oscillators...

  1. Rapid screening and identification of dominant B cell epitopes of HBV surface antigen by quantum dot-based fluorescence polarization assay

    Science.gov (United States)

    Meng, Zhongji; Song, Ruihua; Chen, Yue; Zhu, Yang; Tian, Yanhui; Li, Ding; Cui, Daxiang

    2013-03-01

    A method for quickly screening and identifying dominant B cell epitopes was developed using hepatitis B virus (HBV) surface antigen as a target. Eleven amino acid fragments from HBV surface antigen were synthesized by 9-fluorenylmethoxy carbonyl solid-phase peptide synthesis strategy, and then CdTe quantum dots were used to label the N-terminals of all peptides. After optimizing the factors for fluorescence polarization (FP) immunoassay, the antigenicities of synthetic peptides were determined by analyzing the recognition and combination of peptides and standard antibody samples. The results of FP assays confirmed that 10 of 11 synthetic peptides have distinct antigenicities. In order to screen dominant antigenic peptides, the FP assays were carried out to investigate the antibodies against the 10 synthetic peptides of HBV surface antigen respectively in 159 samples of anti-HBV surface antigen-positive antiserum. The results showed that 3 of the 10 antigenic peptides may be immunodominant because the antibodies against them existed more widely among the samples and their antibody titers were higher than those of other peptides. Using three dominant antigenic peptides, 293 serum samples were detected for HBV infection by FP assays; the results showed that the antibody-positive ratio was 51.9% and the sensitivity and specificity were 84.3% and 98.2%, respectively. In conclusion, a quantum dot-based FP assay is a very simple, rapid, and convenient method for determining immunodominant antigenic peptides and has great potential in applications such as epitope mapping, vaccine designing, or clinical disease diagnosis in the future.

  2. Application of the fluorescence polarization assay for detection of caprine antibodies to Brucella melitensis in areas of high prevalence and widespread vaccination.

    Science.gov (United States)

    Ramírez-Pfeiffer, C; Nielsen, K; Smith, P; Marín-Ricalde, F; Rodríguez-Padilla, C; Gomez-Flores, R

    2007-03-01

    The screening Rose Bengal test (RBT), the buffered plate agglutination test (BPAT), and the confirmatory complement fixation test (CFT) are currently approved by the World Organization for Animal Health (OIE) for diagnosis of goat brucellosis. However, RBT (at 3% or 8% cell concentration) is known to be affected by vaccinal antibodies. In the present study, Mexican and Canadian OIE tests were compared with the fluorescence polarization assay (FPA), alone or in combination, using indirect and competitive enzyme-linked immunosorbent assays as classification variables for goat sera obtained from an area of high prevalence and widespread vaccination. The relative sensitivities and specificities were, respectively, 99.7% and 32.5% for RBT3, 92.8% and 68.8% for RBT8, 98.4% and 84.8% for Canadian CFT, 83.7% and 65.5% for Mexican CFT, and 78.1% and 89.3% for FPA. The use of FPA as the confirmatory test in combination with other tests significantly increased the final specificities of the screening tests alone; BPAT, RBT3, and RBT8 plus FPA resulted in final specificities of 90%, 91.2%, and 91.3%, respectively, whereas for the combinations RBT3 plus Mexican CFT, RBT8 plus Mexican CFT, and BPAT plus Canadian CFT, specificities were 65.5%, 63.2%, and 91.7%, respectively. We suggest that FPA may be routinely applied as an adaptable screening test for diagnosis of goat brucellosis and as a confirmatory test for screening test series. Some advantages of FPA are that its cutoff can be adjusted to improve its sensitivity or specificity, it is a low-cost and easy-to-perform test of choice when specificity is relevant or when an alternative confirmatory test is not available, and it is not affected by vaccination, thus reducing the number of misdiagnosed and killed goats.

  3. Comparison of fluorescence polarization assay with card and complement fixation tests for the diagnosis of goat brucellosis in a high-prevalence area.

    Science.gov (United States)

    Ramirez-Pfeiffer, C; Nielsen, K; Marin-Ricalde, F; Rodríguez-Padilla, C; Gomez-Flores, R

    2006-03-15

    An evaluation of fluorescence polarization assay (FPA) to detect antibodies against Brucella melitensis according to the Mexican Official Norm (NOM) was performed. In this study, a total of 2582 goat serum samples from a high-prevalence area in northeast Mexico where vaccination is applied, were used. Of these, 1094 were classified as NOM negatives (card test (CT) negatives or CT positives/complement fixation test (CFT) negatives) and 1488 as NOM positives (CT and CFT positives). The receiver operator characteristics (ROC) curve analysis was used to obtain the FPA sensitivity (83.5%), specificity (82.2%) and accuracy (88.2%) compared with NOM criteria, using a cut-off value of 89mP for positive samples. In addition, FPA produced 84.1% of negative results versus 65.7% of CT using 1094 CFT negative samples, which indicated that FPA performance was better than CT to detect negative samples or differentiate samples from vaccinated animals. Finally, FPA showed 95.8% sensitivity when using 702 negative non-vaccinated samples. Taken together, these results suggested that FPA might replace CT as a screening test for its better performance compared with CFT, its adjustable cut-off useful in different epidemiological situations, and for its reliability, ease of performance, comparable cost with CT regimen, and potential application in field and high-throughput laboratories. The use of FPA as screening test will help to reduce the percentage of goats wrongly slaughtered because of brucellosis misdiagnosis. More studies on FPA are required for its approval as diagnostic tool for goat brucellosis.

  4. Tungsten disulfide nanosheet and exonuclease III co-assisted amplification strategy for highly sensitive fluorescence polarization detection of DNA glycosylase activity.

    Science.gov (United States)

    Zhao, Jingjin; Ma, Yefei; Kong, Rongmei; Zhang, Liangliang; Yang, Wen; Zhao, Shulin

    2015-08-05

    Herein, we introduced a tungsten disulfide (WS2) nanosheet and exonuclease III (Exo III) co-assisted signal amplification strategy for highly sensitive fluorescent polarization (FP) assay of DNA glycosylase activity. Two DNA glycosylases, uracil-DNA glycosylase (UDG) and human 8-oxoG DNA glycosylase 1 (hOGG1), were tested. A hairpin-structured probe (HP) which contained damaged bases in the stem was used as the substrate. The removal of damaged bases from substrate by DNA glycosylase would lower the melting temperature of HP. The HP was then opened and hybridized with a FAM dye-labeled single strand DNA (DP), generating a duplex with a recessed 3'-terminal of DP. This design facilitated the Exo III-assisted amplification by repeating the hybridization and digestion of DP, liberating numerous FAM fluorophores which could not be adsorbed on WS2 nanosheet. Thus, the final system exhibited a small FP signal. However, in the absence of DNA glycosylases, no hybridization between DP and HP was occurred, hampering the hydrolysis of DP by Exo III. The intact DP was then adsorbed on the surface of WS2 nanosheet that greatly amplified the mass of the labeled-FAM fluorophore, resulting in a large FP value. With the co-assisted amplification strategy, the sensitivity was substantially improved. In addition, this method was applied to detect UDG activity in cell extracts. The study of the inhibition of UDG was also performed. Furthermore, this method is simple in design, easy in implementation, and selective, which holds potential applications in the DNA glycosylase related mechanism research and molecular diagnostics.

  5. Relationship between cyclosporine concentrations obtained using the Roche Cobas Integra and Abbott TDx monoclonal immunoassays in pre-dose and two hour post-dose blood samples from kidney transplant recipients.

    Science.gov (United States)

    Garrido, Manuel J; Hermida, Jesús; Tutor, J Carlos

    2002-12-01

    Current evidence suggests that cyclosporine (CsA) concentration in blood samples taken 2 hours after Neoral microemulsion (Novartis Pharmaceuticals; East Hanover, NJ) administration (C2) predicts clinical events in transplant patients better than the pre-dose (trough) concentration (C0). Similarly, previous findings have shown that the metabolites/CsA ratio is substantially lower in C2 than in C0 samples; however the between-monoclonal immunoassay differences for C2 samples have received little attention in the literature. In 56 C samples and 60 C samples from renal transplant patients, CsA levels were determined using the monoclonal fluorescence polarization immunoassay (mFPIA) from Abbott (Abbott Park, IL) and the homogeneous enzyme immunoassay technique (HEIT) from Roche Diagnostics (Basel, Switzerland). In both cases a high correlation coefficient between the results was obtained (r > or = 0.971), with a linear regression for C0 samples: mFPIA = 1.47 HEIT + 22.0 and for C2 samples: mFPIA = 1.11 HEIT + 71.96. The difference between the linear regression slopes was statistically significant (P < 0.001), and the mFPIA/HEIT ratio was significantly higher for C than for C samples (P < 0.001).

  6. Single-reagent Fluorescence Polarization Immunoassay for Melamine%三聚氰胺单试剂荧光偏振免疫分析法

    Institute of Scientific and Technical Information of China (English)

    王强; 黄启欣; 孙远明; 刘英菊; 徐振林; 雷红涛

    2013-01-01

    用三聚氰胺半抗原(MEL)与异硫氰酸荧光素乙二胺(EDF)反应合成了荧光示踪物MEL-EDF,示踪物与三聚氰胺抗体反应得到稳定的单试剂免疫复合物,考察了其结合动力学和置换动力学过程,建立了一种三聚氰胺单试剂荧光偏振免疫分析方法(SR-FPIA).该方法的检出限(LOD)为3.2 ng/mL,半抑制浓度(ICso)为157.1 ng/mL,检测范围(IC20 ~ IC80)为12.2~1012.4 ng/mL,能够满足国家标准和国际食品法典委员会(CAC)对于食品中三聚氰胺最高残留限量的检测要求.整个检测过程在15 min内完成,并且单试剂免疫复合物在4℃下至少可稳定保存30 d以上.本研究对开发三聚氰胺新型免疫检测方法具有重要意义.%Fluorescence-labeled melamine tracer ( MEL-EDF) was synthesized via the reaction of melamine hapten ( MEL ) with 1 - (2-aminoethyl) -3 - ( 3', 6' -dihydroxy-3 -oxo-3 H-spiro [ isobenzofuran-1,9' -xanthene ] -5 -yl) thiourea( EDF) . The tracer was then incubated with the antibody to prepare the single reagent immunocom-plex, and both the binding and displacement kinetics were evaluated to obtain the equilibration time. Finally, a single reagent fluorescence polarization immunoassay(SR-FPIA) was developed to measure melamine. The SR-FPIA method demonstrated a detection limit (LOD) of 3. 2 ng/mL, a 50% inhibition value (IC50 ) of 157. 1 ng/mL and a working range( IC20—IC80) of 12. 2—1012. 4 ng/mL. The results indicated the proposed method can meet the detection requirement for the maximum residue level of melamine set by Chinese government and Codex Alimentarius Commission( CAC). The detection could be finished within 15 min, and the obtained single reagent immunocomplex was stable for more than 30 days at 4 °C. This work will benefit to further development of SR-FPIA kit for melamine.

  7. Validation of a fluorescence polarization assay (FPA) performed in microplates and comparison with other tests used for diagnosing B. melitensis infection in sheep and goats.

    Science.gov (United States)

    Minas, A; Stournara, A; Minas, M; Stack, J; Petridou, E; Christodoulopoulos, G; Krikelis, V

    2007-03-30

    Fluorescence polarization assay (FPA) is a relatively new test for the serological diagnosis of Brucella spp. infection in animals. FPA, carried out in 96-well microplate format, was validated here for diagnosing B. melitensis infection in sheep and goats. This study included sera from 1933 sheep and goats, from animals reared in naturally infected flocks (verified by culture) and showing a positive reaction to two different tests conducted in parallel. In addition, 2154 sera originating from healthy sheep and goats, reared in areas where B. melitensis had never been isolated, were assayed. The optimum cut-off value offering the highest diagnostic sensitivity (DSn) and diagnostic specificity (DSp) was determined at 15 mP over the mean value of the buffer control used in each microplate as determined by receiver operating characteristic analysis. The DSn and DSp of the FPA for small ruminants carried out in microplates at this cut-off value were calculated to be 95.9% and 97.9% with 95% confidence intervals (95% CI) of 94.9-97.7% and 97.2-98.4%, respectively. The accuracy of the FPA, as expressed by determination of the area under the curve, was 0.991. Indirect ELISA and FPA tests offered the highest DSn when compared with the Rose Bengal test, the complement fixation test, the modified Rose Bengal test and competitive ELISA. The parallel or serial combination of FPA with indirect ELISA offers the highest DSn and DSp. As temperature can affect the results of the FPA, all reagents must be at the same temperature and the standard for comparison must always be read under the same conditions as the sera under test. FPA performed in microplates is a promising assay; the DSn and accuracy are better than those of the tests currently approved for diagnosing B. melitensis in small ruminants. Because of its simplicity, speed, and accuracy, this test can improve capacity for laboratory testing and the efficacy of an eradication program based on a test-and-slaughter policy.

  8. [Role of ultrasensitive TSH assay and ultrarapid total thyroxine assay in the thyroid studies].

    Science.gov (United States)

    Fragu, P; Comoy, E; Noël, M; Lounis, M; Patois, E; Parmentier, C

    1987-11-07

    The diagnostic value of high sensitivity thyrotrophin assay (HS-TSH) and that of ultra-short determination of total thyroxine (T4) by fluorescence polarization (T4-TDX) were evaluated in 284 patients (29 hyperthyroid, 137 euthyroid without treatment and 118 under substitutive therapy). After comparing the clinician's first impression with the results of these laboratory tests the proportion of correctly classified untreated euthyroid patients was the same with T4-TDX as with HS-TSH (90%). In contrast, this proportion in hyperthyroid patients was about twice as low with HS-TSH (23%) as with T4-TDX (42%). While HS-TSH gives a better diagnostic evaluation, T4-TDX is an excellent indicator of the degree of hyperthyroidism. In patients under suppressive therapy HS-TSH and T4-TDX provide a better evaluation of therapeutic effectiveness.

  9. Normalized polarization ratios for the analysis of cell polarity.

    Directory of Open Access Journals (Sweden)

    Raz Shimoni

    Full Text Available The quantification and analysis of molecular localization in living cells is increasingly important for elucidating biological pathways, and new methods are rapidly emerging. The quantification of cell polarity has generated much interest recently, and ratiometric analysis of fluorescence microscopy images provides one means to quantify cell polarity. However, detection of fluorescence, and the ratiometric measurement, is likely to be sensitive to acquisition settings and image processing parameters. Using imaging of EGFP-expressing cells and computer simulations of variations in fluorescence ratios, we characterized the dependence of ratiometric measurements on processing parameters. This analysis showed that image settings alter polarization measurements; and that clustered localization is more susceptible to artifacts than homogeneous localization. To correct for such inconsistencies, we developed and validated a method for choosing the most appropriate analysis settings, and for incorporating internal controls to ensure fidelity of polarity measurements. This approach is applicable to testing polarity in all cells where the axis of polarity is known.

  10. Polarized fluorescence in an electric field: steady state and transient values for the fourth moment of the orientation function at arbitrary fields.

    Science.gov (United States)

    Sokerov, S; Weill, G

    1979-07-01

    Steady state and time dependent expressions for the field dependence of the fourth moment of the orientation function at arbitrary fields, which are requested for the interpretation of polarisation of fluorescence in an electric field, have been obtained for permanent and induced dipole orientation. Some general features of the results and some problems connected with their application are pointed out.

  11. Research on Polarized Three-Dimensional Fluorescence Spectra of Milk Solution%湖泊水体三维荧光光谱的PARAFAC法在污染源解析中的应用

    Institute of Scientific and Technical Information of China (English)

    祝鹏; 华祖林; 李惠民

    2012-01-01

    Polarized three-dimensional fluorescence spectra of different kinds of milk were measured, including pure milk, milk with high calcium, and milk with high calcium but low fat produced by YiLi and MengNiu. It was found that the fluorescence intensity is stronger when excitation and emission polarizer orientation is parallel. The angle between excitation dipole and emission dipole of all kinds of milk equivalent chromophore was estimated by a simple model, indicating that they all less than 40? The angle for milk with high calcium but low fat is less than that of pure milk and milk with high calcium. And in the experiment, the polarized fluorescence intensity of milk with high calcium but low fat is significantly greater than the others, which fitted with the model estimation.%基于三维荧光光谱矩阵的 PARAFAC 模型中因子得分反映混合物各因子相对浓度和比例这一特征,将其应用到混合物源解析的研究.对于因子与来源物质光谱不一致的情况考虑将来源物质荧光矩阵和混合物荧光矩阵均作为模型三维数据矩阵的元素进行分析,推导出混合样品与源物质荧光矩阵之间的关系式.该关系式系数由因子得分组成,反映了混合样品各来源物贡献率的相对大小,能够作为来源物量化研究的参考指数.在湖泊污染物源解析的应用中,利用混合水样和污染源水样荧光光谱矩阵建立上述关系式,关系式各系数可作为湖泊水体污染源源解析研究的参考.

  12. Breaking the diffraction-limited resolution barrier in fiber-optical two-photon fluorescence endoscopy by an azimuthally-polarized beam.

    Science.gov (United States)

    Gu, Min; Kang, Hong; Li, Xiangping

    2014-01-10

    Although fiber-optical two-photon endoscopy has been recognized as a potential high-resolution diagnostic and therapeutic procedure in vivo, its resolution is limited by the optical diffraction nature to a few micrometers due to the low numerical aperture of an endoscopic objective. On the other hand, stimulated emission depletion (STED) achieved by a circularly-polarized vortex beam has been used to break the diffraction-limited resolution barrier in a bulky microscope. It has been a challenge to apply the STED principle to a fiber-optical two-photon endoscope as a circular polarization state cannot be maintained due to the birefringence of a fiber. Here, we demonstrate the first fiber-optical STED two-photon endoscope using an azimuthally-polarized beam directly generated from a double-clad fiber. As such, the diffraction-limited resolution barrier of fiber-optical two-photon endoscopy can be broken by a factor of three. Our new accomplishment has paved a robust way for high-resolution in vivo biomedical studies.

  13. Application of Partial Least Square (PLS) Analysis on Fluorescence Data of 8-Anilinonaphthalene-1-Sulfonic Acid, a Polarity Dye, for Monitoring Water Adulteration in Ethanol Fuel.

    Science.gov (United States)

    Kumar, Keshav; Mishra, Ashok Kumar

    2015-07-01

    Fluorescence characteristic of 8-anilinonaphthalene-1-sulfonic acid (ANS) in ethanol-water mixture in combination with partial least square (PLS) analysis was used to propose a simple and sensitive analytical procedure for monitoring the adulteration of ethanol by water. The proposed analytical procedure was found to be capable of detecting even small adulteration level of ethanol by water. The robustness of the procedure is evident from the statistical parameters such as square of correlation coefficient (R(2)), root mean square of calibration (RMSEC) and root mean square of prediction (RMSEP) that were found to be well with in the acceptable limits.

  14. Solvent effect on absorption and fluorescence spectra of three biologically active carboxamides (C1, C2 and C3). Estimation of ground and excited state dipole moment from solvatochromic method using solvent polarity parameters.

    Science.gov (United States)

    Patil, N R; Melavanki, R M; Kapatkar, S B; Ayachit, N H; Saravanan, J

    2011-05-01

    The absorption and fluorescence spectra of three Carboxamides namely (E)-2-(4-Chlorobenzylideneamino)-N-(2-chlorophenyl)-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxamide (C(1)), (E)-N-(3-Chlorophenyl)-2-(3, 4-dimethoxybenzylideneamino)-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxamide (C(2)) and (E)-N-(3-Chlorophenyl)-2-(3,4,5-trimethoxybenzylideneamino)-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxamide (C(3)) have been recorded at room temperature in solvents of different polarities using dielectric constant (ε) and refractive index (n). Experimental ground (μ(g)) and excited (μ(e)) state dipole moments are estimated by means of solvatochromic shift method and also the excited dipole moments are estimated in combination with ground state dipole moments. It was estimated that dipole moments of the excited state were higher than those of the ground state of all three molecules. Further, the changes in dipole moment (Δμ) were calculated both from solvatochromic shift method and on the basis of microscopic empirical solvent polarity parameter (E(N)(T)) and the values are compared.

  15. Single molecule investigations of DNA looping using the tethered particle method and translocation by acto-myosin using polarized total internal reflection fluorescence microscopy

    Science.gov (United States)

    Beausang, John F.

    Single molecule biophysics aims to understand biological processes by studying them at the single molecule level in real time. The proteins and nucleic acids under investigation typically exist in an aqueous environment within ˜ ten degrees of room temperature. These seemingly benign conditions are actually quite chaotic at the nanoscale, where single bio-molecules perform their function. As a result, sensitive experiments and statistical analyses are required to separate the weak single molecule signal from its background. Protein-DNA interactions were investigated by monitoring DNA looping events in tethered particle experiments. A new analysis technique, called the Diffusive hidden Markov method, was developed to extract kinetic rate constants from experimental data without any filtering of the raw data; a common step that improves the signal to noise ratio, but at the expense of lower time resolution. In the second system, translocation of the molecular motor myosin along its actin filament track was studied using polarized total internal reflection (polTIRF) microscopy, a technique that determines the orientation and wobble of a single fluorophore attached to the bio-molecule of interest. The range of resolvable angles was increased 4-fold to include a hemisphere of possible orientations. As a result, the handedness of actin filament twirling as it translocated along a myosin-coated surface was determined to be left-handed. The maximum time resolution of a polTIRF setup was increased 50-fold, in part by recording the arrival times and polarization state of single photons using a modified time-correlated single photon counting device. A new analysis, the Multiple Intensity Change Point algorithm, was developed to detect changes in molecular orientation and wobble using the raw time-stamped data with no user-defined bins or thresholds. The analysis objectively identified changes in the orientation of a bifunctional-rhodamine labeled calmodulin that was attached

  16. Fluorescence spectroscopy

    DEFF Research Database (Denmark)

    Bagatolli, Luis

    2016-01-01

    Fluorescence spectroscopy is a powerful experimental tool used by scientists from many disciplines. During the last decades there have been important developments on distinct fluorescence methods, particularly those related to the study of biological phenomena. This chapter discusses...

  17. Detection and Genotyping of Human Papillomavirus DNA in Cervical Cancer Tissues with Fluorescence Polarization%宫颈癌组织人乳头瘤病毒的荧光偏振基因分型

    Institute of Scientific and Technical Information of China (English)

    高艳娥; 张菊; 吴静; 陈中灿; 阎小君

    2003-01-01

    采用荧光偏振人乳头瘤病毒( human papillomavirus, HPV )分型新方法探讨了8种常见型别HPV在陕西宫颈癌患者中的流行情况. 首先, 用HPV GP5 +/GP6 +通用引物PCR扩增65例早期宫颈癌(Ⅱa期内)和72例慢性宫颈炎病变组织DNA粗提物, 继之将模板指导的末端延伸反应与荧光偏振检测技术结合(TDI-FP), 用GP5 +/GP6 +扩增区内的HPV 6、11、16、18、31、33、35和58型特异性探针与PCR产物杂交后, 荧光素标记的特异碱基(TAMRA-ddTTP 或R110-ddGTP)在GP5 +/GP6 +产物中相应的模板指导下, 掺入延伸至相应探针末端, 致使对应的TAMRA 或R110 FP值升高, 从而对扩增的HPV阳性产物进行HPV分型. 65例宫颈癌患者中检出HPV 57例, 阳性率87.69%, 72例慢性宫颈炎患者中检出HPV 28例, 阳性率38.89%, 两组间HPV阳性率有显著性差异. 宫颈癌与慢性宫颈炎患者中4种最常见的HPV型别分别是HPV 16 (45.6%)、HPV 18 (22.8%)、HPV 58 (17.5%)、HPV 31 (7.02%)和HPV 16 (35.7%)、HPV 11 (32.1%)、HPV 6 (21.4%)、HPV 18 (10.7%). 慢性宫颈炎患者中检出的HPV型别57.14%属高危型. HPV 16在两组中均最为多见. 中国陕西宫颈疾病患者中HPV 感染有其特点, 世界范围内少见的HPV 58在陕西宫颈癌与慢性宫颈炎患者中均较为多见, 在进行HPV新诊断方法及疫苗研制时应考虑到这种特点.%To evaluate the type-specific prevalence of eight common types of human papillomavirus (HPV) in patients with cervical cancer living in Shanxi, China, with fluorescence polarization detection, crude DNA extracted from 137 samples of early-stage cervical cancer (within stage IIa) and chronic cervicitis was subjected to HPV L1 consensus GP5 +/GP6 + system. Then, the HPV-positive products identified by GP5 +/GP6 + PCR were genotyped based on template-directed dye-terminator incorporation assay with fluorescence polarization detection (TDI-FP): the PCR products were respectively hybridized with designed

  18. Polarization developments

    Energy Technology Data Exchange (ETDEWEB)

    Prescott, C.Y.

    1993-07-01

    Recent developments in laser-driven photoemission sources of polarized electrons have made prospects for highly polarized electron beams in a future linear collider very promising. This talk discusses the experiences with the SLC polarized electron source, the recent progress with research into gallium arsenide and strained gallium arsenide as a photocathode material, and the suitability of these cathode materials for a future linear collider based on the parameters of the several linear collider designs that exist.

  19. Nine New Fluorescent Probes

    Science.gov (United States)

    Lin, Tsung-I.; Jovanovic, Misa V.; Dowben, Robert M.

    1989-06-01

    Absorption and fluorescence spectroscopic studies are reported here for nine new fluorescent probes recently synthesized in our laboratories: four pyrene derivatives with substituents of (i) 1,3-diacetoxy-6,8-dichlorosulfonyl, (ii) 1,3-dihydroxy-6,8-disodiumsulfonate, (iii) 1,3-disodiumsulfonate, and (iv) l-ethoxy-3,6,8-trisodiumsulfonate groups, and five [7-julolidino] coumarin derivatives with substituents of (v) 3-carboxylate-4-methyl, (vi) 3- methylcarboxylate, (vii) 3-acetate-4-methyl, (viii) 3-propionate-4-methyl, and (ix) 3-sulfonate-4-methyl groups. Pyrene compounds i and ii and coumarin compounds v and vi exhibit interesting absorbance and fluorescence properties: their absorption maxima are red shifted compared to the parent compound to the blue-green region, and the band width broadens considerably. All four blue-absorbing dyes fluoresce intensely in the green region, and the two pyrene compounds emit at such long wavelengths without formation of excimers. The fluorescence properties of these compounds are quite environment-sensitive: considerable spectral shifts and fluorescence intensity changes have been observed in the pH range from 3 to 10 and in a wide variety of polar and hydrophobic solvents with vastly different dielectric constants. The high extinction and fluorescence quantum yield of these probes make them ideal fluorescent labeling reagents for proteins, antibodies, nucleic acids, and cellular organelles. The pH and hydrophobicity-dependent fluorescence changes can be utilized as optical pH and/or hydrophobicity indicators for mapping environmental difference in various cellular components in a single cell. Since all nine probes absorb in the UV, but emit at different wavelengths in the visible, these two groups of compounds offer an advantage of utilizing a single monochromatic light source (e.g., a nitrogen laser) to achieve multi-wavelength detection for flow cytometry application. As a first step to explore potential application in

  20. Polarization, political

    NARCIS (Netherlands)

    M. Wojcieszak

    2015-01-01

    Polarization has been studied in three different forms: on a social, group, and individual level. This entry first focuses on the undisputed phenomenon of elite polarization (i.e., increasing adherence of policy positions among the elites) and also outlines different approaches to assessing mass pol

  1. Polar Codes

    Science.gov (United States)

    2014-12-01

    QPSK Gaussian channels . .......................................................................... 39 vi 1. INTRODUCTION Forward error correction (FEC...Capacity of BSC. 7 Figure 5. Capacity of AWGN channel . 8 4. INTRODUCTION TO POLAR CODES Polar codes were introduced by E. Arikan in [1]. This paper...Under authority of C. A. Wilgenbusch, Head ISR Division EXECUTIVE SUMMARY This report describes the results of the project “More reliable wireless

  2. Polarization holography

    DEFF Research Database (Denmark)

    Nikolova, L.; Ramanujam, P.S.

    Current research into holography is concerned with applications in optically storing, retrieving, and processing information. Polarization holography has many unique properties compared to conventional holography. It gives results in high efficiency, achromaticity, and special polarization...... properties. This books reviews the research carried out in this field over the last 15 years. The authors provide basic concepts in polarization and the propagation of light through anisotropic materials, before presenting a sound theoretical basis for polarization holography. The fabrication...... and characterization of azobenzene based materials, which remain the most efficient for the purpose, is described in detail. This is followed by a description of other materials that are used in polarization holography. An in-depth description of various applications, including display holography and optical storage...

  3. Polarization holography

    DEFF Research Database (Denmark)

    Nikolova, L.; Ramanujam, P.S.

    properties. This books reviews the research carried out in this field over the last 15 years. The authors provide basic concepts in polarization and the propagation of light through anisotropic materials, before presenting a sound theoretical basis for polarization holography. The fabrication......Current research into holography is concerned with applications in optically storing, retrieving, and processing information. Polarization holography has many unique properties compared to conventional holography. It gives results in high efficiency, achromaticity, and special polarization...... and characterization of azobenzene based materials, which remain the most efficient for the purpose, is described in detail. This is followed by a description of other materials that are used in polarization holography. An in-depth description of various applications, including display holography and optical storage...

  4. Fluorescence Studies of Selected 2-Alkylaminopyrimidines

    Directory of Open Access Journals (Sweden)

    B. K. Low

    2004-06-01

    Full Text Available The reactions of 2-chloropyrimidine with methylamine, ethylamine and piperidine gave the corresponding 2-N-methylamino-, 2-N-ethylamino- and 2N- piperidinopyrimidines, respectively. The fluorescence properties of these alkylamino derivatives in chloroform, ethyl acetate, carbon tetrachloride, acetone, ether, ethanol and methanol were studied. All the alkylamino derivatives showed the highest fluorescence intensity in polar protic solvents; thus 2-N-methylaminopyrimidine (highest fluorescence intensity at 377 nm when excited at 282 nm and 2-N-ethylaminopyrimidine (highest fluorescence intensity at 375 nm, when excited at 286 nm showed the highest fluorescence in methanol. In ethanol, 2-N-piperidinopyrimidine showed a fluorescence peak at 403 nm when excited at 360 nm and in chloroform it fluoresced at 392 nm when excited at 356 nm.

  5. 非对称PCR-FP技术同步检测HSV-1/-2、CMV和EBV%Simultaneous detection of four major human herpesviruses by asymmetric PCR-fluorescence polarization assay

    Institute of Scientific and Technical Information of China (English)

    张菊; 吴中亮; 李丁; 王香玲; 梁平; 郭宴海; 李宏伟; 颜真

    2009-01-01

    目的 应用非对称PCR-荧光偏振(FP)技术建立一种同步检测全血中4种主要疱疹病毒(单纯疱疹病毒1/2型,巨细胞病毒、EB病毒)的新方法.方法 以人疱疹病毒属通用引物行非对称PCR,扩增从179例样本中抽提的DNA.PCR扩增产物与特异性单纯疱疹病毒1/2型(HSV-1/2)、巨细胞病毒(CMV)和EB病毒(EBV)寡核苷酸探针混合物温育杂交,荧光偏振检测技术检测杂交液荧光偏振值,据荧光偏振值判断病毒感染类型,并以DNA序列测定结果为参照.结果 与DNA序列测定的阳性检测符合率为100%,但DNA序列测定检测均未检出多重混合感染.非对称PCR-FP方法对HSV-1/-2检测的灵敏度达到1.0×10~3拷贝/ml,时EBV和cMV检测的灵敏度达到2.0×10~3拷贝/ml.结论 本法对于4种主要疱疹病毒感染的筛查及预防、预后判断具重要价值.%Objective To establish a novel method to detect four major human herpesvirus simultaneously by fluorescence polarization (FP) assay based on asymmetric PCR. Methods A consensus primer system in human herpesvirus was used in an asymmetric PCR. The probes of herpes simplex virus types 1 and 2 (HSV-1/-2) ,cytomegalovirus (CMV) ,and Epstein-Barr virus (EBV) labeled with different fluorophores were hybridized respectively with target amplicons. The infection was determined by the increased FP value. The DNA extracted from 179 samples was subjected to FP and sequence assay to evaluate the feasibility of this method. Results The mini-mum detection level of FP assay was 10 genome copies for HSV -1/ -2 , 20 genome copies for both EBV and CMV. FP assay could detect co-infections more effectively than sequence assay. Conclusions A practical method was developed for the simultaneous detection of the four major human herpesviruses by FP assay based on an asymmetric PCR.

  6. Polarized photoluminescence from nematic and chiral- nematic liquid crystalline films

    Science.gov (United States)

    Conger, Brooke Morgan

    Polarization control is key to optoelectronics in terms of the processing and display of optical information. In principle, photonic or electronic excitation of anisotropic films should result in polarized light emission. Because of spontaneous molecular self-assembly, liquid crystals are ideal for the exploration of polarized luminescence. Although most studies on polarized luminescence have been based on liquid crystalline fluid films, solid films are preferred in view of morphological stability. Therefore, the theme of my thesis is the study of polarized luminescence from various fluorescent liquid crystal systems. From the fundamental perspective, a theory modeling the process of polarized photoluminescence was validated using fluorophore doped fluid liquid crystal films. To provide the morphological stability crucial to practical application, polarized fluorescence using vitrifiable and polymeric liquid crystals functionalized with fluorescent moieties was investigated. In addition, liquid crystalline π- conjugated polymers were synthesized and characterized as a new class of optical polymers. The effect of the emission source on achievable polarization from pyrene and carbazole systems was also elucidated. The main observations are as follows: (1) The observed degrees of polarization for all fluorescent liquid crystal systems were found to agree with the theories governing polarized fluorescence. (2) Low molar mass vitrifiable and polymeric liquid crystalline cyanoterphenyl and cyanotolane derivatives were found to yield moderate polarized fluorescence. Monomer emission was established as the decay pathway for the precursors and cyclohexane and polymethacrylate derivatives. (3) Ordered solid films from thiophene and p-phenylene π-conjugated polymers were found to induce significant degrees of polarized fluorescence. (4) Emission from glass-forming pyrenyl derivatives exhibited excimer emission in dilute solution and neat film, whereas in solid hosts it was

  7. Polarizing cues.

    Science.gov (United States)

    Nicholson, Stephen P

    2012-01-01

    People categorize themselves and others, creating ingroup and outgroup distinctions. In American politics, parties constitute the in- and outgroups, and party leaders hold sway in articulating party positions. A party leader's endorsement of a policy can be persuasive, inducing co-partisans to take the same position. In contrast, a party leader's endorsement may polarize opinion, inducing out-party identifiers to take a contrary position. Using survey experiments from the 2008 presidential election, I examine whether in- and out-party candidate cues—John McCain and Barack Obama—affected partisan opinion. The results indicate that in-party leader cues do not persuade but that out-party leader cues polarize. This finding holds in an experiment featuring President Bush in which his endorsement did not persuade Republicans but it polarized Democrats. Lastly, I compare the effect of party leader cues to party label cues. The results suggest that politicians, not parties, function as polarizing cues.

  8. Fluorescent microspheres

    Science.gov (United States)

    Rembaum, A.

    1978-01-01

    Latex particles with attached antibodies have potential biochemical and environmental applications. Human red blood cells and lymphocytes have been labeled with fluorescent microspheres by either direct or indirect immunological technique. Immunolatex spheres can also be used for detecting and localizing specific cell surface receptors. Hormones and toxins may also be bondable.

  9. Development and application of fluorescence polarization assay for high throughput screening of geldanamycin-Hsp90α binding%荧光偏振法建立格尔德霉素-Hsp90α结合高通量筛选模型及其应用

    Institute of Scientific and Technical Information of China (English)

    董飚; 陶佩珍; 李艳萍; 李玉环

    2011-01-01

    Objective:To establish a high throughput screening, fluorescence polarization assay of binding between Hsp90α and geldanamycin, to identify novel geldanamycin derivatives. Methods: The assay was based on the fluorescence polarization theory by using fluorescein isothiocyanate (FITC) labeled geldanamycin (GA) for binding to Hsp90α in homogeneous solution. Affinity of novel geldanamycin derivatives for Hsp90α was measured by competitive assay. Results:The fluorescence polarization assay for Hsp90 using a fluorescent GA ligand was successfully established, of which Z factor value reached 0. 641. Among the measured geldanamycin derivative samples, GA-APML and GA-AEPD caused inhibition effects on the binding of GA-Hsp90α with IC50 of 82.98 and 90. 06 nmol·L-1, respectively. Conclusion: The fluorescence polarization assay for GA-Hsp binding basically meets the standard required by high throughput screening experiments. The designed geldanamycin derivatives still have same affinity to Hsp90α as the geldanamycin itself, which shows it is feasible to modify the structure of geldanamycin at these sites.%目的:建立格尔德霉素(geldanamycin,GA)-Hsp90α结合高通量荧光偏振法筛选模型及应用此模型探查新的格尔德霉素衍生物.方法:本模型利用荧光偏振原理,在均相溶液中,以异硫氰酸荧光素(FITC)标记的格尔德霉素作为配基,与Hsp90α蛋白作用,采用荧光仪检测荧光偏振值.以竞争性结合方式评价新格尔德霉素衍生物对Hsp90α的亲和力,以期找出更好的格尔德霉素衍生物.结果:成功建立了荧光偏振原理的格尔德霉素-Hsp90α结合模型,其Z因子可达0.641.所测试的格尔德霉素衍生物样品中,GA-APML和GA-AEPD抑制GA-Hsp90α结合的IC50分别为82.98和90.06 nmol·L-1.结论:建立的格尔德霉素-Hsp90α结合荧光偏振法模型基本达到进行高通量实验所需的标准.所设计格尔德霉素衍生物仍具备与格尔德霉素相同的对Hsp90

  10. Polarized Campuses.

    Science.gov (United States)

    Parr, Susan Resneck

    1991-01-01

    On college campuses, the climate is polarized because of intolerance and discrimination, censorship, factionalism, and anger among students and faculty. As a result, the campus is in danger of becoming dominated by political issues and discouraging the exchange of ideas characteristic of a true liberal arts education. (MSE)

  11. Polar Diving

    Science.gov (United States)

    2006-01-01

    3 July 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layers exposed by erosion in a trough within the north polar residual cap of Mars, diving beneath a younger covering of polar materials. The layers have, since the Mariner 9 mission in 1972, been interpreted to be composed of a combination of dust and ice in unknown proportions. In this scene, a layer of solid carbon dioxide, which was deposited during the previous autumn and winter, blankets the trough as well as the adjacent terrain. Throughout northern spring, the carbon dioxide will be removed; by summer, the layers will be frost-free. Location near: 81.4oN, 352.2oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Spring

  12. Plasmonics Enhanced Smartphone Fluorescence Microscopy

    KAUST Repository

    Wei, Qingshan

    2017-05-12

    Smartphone fluorescence microscopy has various applications in point-of-care (POC) testing and diagnostics, ranging from e.g., quantification of immunoassays, detection of microorganisms, to sensing of viruses. An important need in smartphone-based microscopy and sensing techniques is to improve the detection sensitivity to enable quantification of extremely low concentrations of target molecules. Here, we demonstrate a general strategy to enhance the detection sensitivity of a smartphone-based fluorescence microscope by using surface-enhanced fluorescence (SEF) created by a thin metal-film. In this plasmonic design, the samples are placed on a silver-coated glass slide with a thin spacer, and excited by a laser-diode from the backside through a glass hemisphere, generating surface plasmon polaritons. We optimized this mobile SEF system by tuning the metal-film thickness, spacer distance, excitation angle and polarization, and achieved ~10-fold enhancement in fluorescence intensity compared to a bare glass substrate, which enabled us to image single fluorescent particles as small as 50 nm in diameter and single quantum-dots. Furthermore, we quantified the detection limit of this platform by using DNA origami-based brightness standards, demonstrating that ~80 fluorophores per diffraction-limited spot can be readily detected by our mobile microscope, which opens up new opportunities for POC diagnostics and sensing applications in resource-limited-settings.

  13. Polarized light microscopy: principles and practice.

    Science.gov (United States)

    Oldenbourg, Rudolf

    2013-11-01

    Polarized light microscopy provides unique opportunities for analyzing the molecular order in heterogeneous systems, such as living cells and tissues, without using exogenous dyes or labels. This article briefly discusses the theory of polarized light microscopy and elaborates on its practice using a traditional polarized light microscope and more specialized polarization microscopes such as the LC-PolScope, Oosight, or Abrio. The microscope components specific to analyzing the polarization of light, such as polarizer and compensator, are introduced, and quantitative techniques for measuring the birefringence of the specimen point by point using a traditional polarizing microscope are discussed. The new LC-PolScope greatly improves the analytic power of the technique, providing quantitative birefringence data simultaneously for every image point, thereby revealing molecular order with unprecedented sensitivity and at the highest resolution of the light microscope. Practical aspects discussed include the choice of optics, sample preparation, and combining polarized light with differential interference contrast and fluorescence microscopy. A glossary of polarization optical terms is also included to facilitate the discussion of observations made with a polarized light microscope.

  14. Some fluorescence properties of dimethylaminochalcone and its novel cyclic analogues

    Science.gov (United States)

    Tomečková, Vladimíra; Poškrobová, Martina; Štefanišinová, Miroslava; Perjési, Pál

    2009-12-01

    This paper demonstrates the basic character (polarity, solubility, colour, absorption and fluorescence quantum yield) of synthetic dimethylaminochalcone ( 1) and its cyclic analogues measured in toluene, chloroform, dimethylsulfoxide and ethanol, which have been studied by absorption and fluorescence spectroscopy. The biologically active dye 4'-dimethylaminochalcone ( 1b) and its less flexible analogues 4-dimethylaminoindanone ( 2b), -tetralone ( 3b), and -benzosuberone ( 4b) are lipophilic molecules that displayed the best solubility in toluene and chloroform. The highest fluorescence and quantum yields of compounds 1 and 2 have been obtained in DMSO and chloroform. Quenching effect of fluorescence compounds ( 1- 4) has been studied in the mixture of the most polar organic solvents DMSO and water. In the presence of water, fluorescence of compound 1 has been quenched the best from all studied chalcones and emission maxima of molecules 1- 4 have been shifted to the longer wavelengths. Quenching effect of fluorescence by water was in order 1 > 2 > 3 > 4.

  15. Anthracylmethyl Benzoazacrown Ether as Selective Fluorescence Sensors for Zn2+

    Institute of Scientific and Technical Information of China (English)

    Li Hua JIA; Xiang Feng GUO; Yuan Yuan LIU; Xu Hong QIAN

    2004-01-01

    A new benzoazacrown ether fluorescence sensor was synthesized with 9-anthrylmethyl chloride and benzoaza-15-crown-5 in CH3CN, which particularly shows a strong affinity for Zn2+. Its fluorescence quantum yield increase more than one order of magnitude and a red shift could be noticed when passing from the apolar to the polar solvent.

  16. An Empirical Algorithm for Wave Retrieval from Co-Polarization X-Band SAR Imagery

    Directory of Open Access Journals (Sweden)

    Weizeng Shao

    2017-07-01

    Full Text Available In this study, we proposed an empirical algorithm for significant wave height (SWH retrieval from TerraSAR-X/TanDEM (TS-X/TD-X X-band synthetic aperture radar (SAR co-polarization (vertical-vertical (VV and horizontal-horizontal (HH images. As the existing empirical algorithm at X-band, i.e., XWAVE, is applied for wave retrieval from HH-polarization TS-X/TD-X image, polarization ratio (PR has to be used for inverting wind speed, which is treated as an input in XWAVE. Wind speed encounters saturation in tropical cyclone. In our work, wind speed is replaced by normalized radar cross section (NRCS to avoiding using SAR-derived wind speed, which does not work in high winds, and the empirical algorithm can be conveniently implemented without converting NRCS in HH-polarization to NRCS in VV-polarization by using X-band PR. A total of 120 TS-X/TD-X images, 60 in VV-polarization and 60 in HH-polarization, with homogenous wave patterns, and the coincide significant wave height data from European Centre for Medium-Range Weather Forecasts (ECMWF reanalysis field at a 0.125° grid were collected as a dataset for tuning the algorithm. The range of SWH is from 0 to 7 m. We then applied the algorithm to 24 VV and 21 HH additional SAR images to extract SWH at locations of 30 National Oceanic and Atmospheric Administration (NOAA National Data Buoy Center (NDBC buoys. It is found that the algorithm performs well with a SWH stander deviation (STD of about 0.5 m for both VV and HH polarization TS-X/TD-X images. For large wave validation (SWH 6–7 m, we applied the empirical algorithm to a tropical cyclone Sandy TD-X image acquired in 2012, and obtained good result with a SWH STD of 0.3 m. We concluded that the proposed empirical algorithm works for wave retrieval from TS-X/TD-X image in co-polarization without external sea surface wind information.

  17. Polar Shapelets

    CERN Document Server

    Massey, R; Massey, Richard; Refregier, Alexandre

    2004-01-01

    The shapelets method for astronomical image analysis is based around the decomposition of localised objects into a series of orthogonal components with particularly convenient mathematical properties. We extend the "Cartesian shapelet" formalism from earlier work, and construct "polar shapelet" basis functions that separate an image into components with explicit rotational symmetries. This provides a more compact representation of typical galaxy shapes, and its physical interpretation is frequently more intuitive. Linear coordinate transformations can be simply expressed using this basis set, and shape measures (including object photometry, astrometry and galaxy morphology estimators) take a naturally elegant form. Particular attention is paid to the analysis of astronomical survey images, and we test shapelet techniques with real data from the Hubble Space Telescope. We present a practical method to automatically optimise the quality of an arbitrary shapelet decomposition in the presence of noise, pixellisat...

  18. Mueller matrix signature in advanced fluorescence microscopy imaging

    Science.gov (United States)

    Mazumder, Nirmal; Qiu, Jianjun; Kao, Fu-Jen; Diaspro, Alberto

    2017-02-01

    We have demonstrated the measurement and characterization of the polarization properties of a fluorescence signal using four-channel photon counting based Stokes-Mueller polarization microscopy. Thus, Lu-Chipman decomposition was applied to extract the critical polarization properties such as depolarization, linear retardance and the optical rotation of collagen type I fiber. We observed the spatial distribution of anisotropic and helical molecules of collagen from the reconstructed 2D Mueller images based on the fluorescence signal in a pixel-by-pixel manner.

  19. Polarization-correlated photon pairs from a single ion

    CERN Document Server

    Rohde, F; Piro, N; Almendros, M; Schuck, C; Dubin, F; Eschner, J

    2009-01-01

    In the fluorescence light of a single atom, the probability for emission of a photon with certain polarization depends on the polarization of the photon emitted immediately before it. Here correlations of such kind are investigated with a single trapped calcium ion by means of second order correlation functions. A theoretical model is developed and fitted to the experimental data, which show 91% probability for the emission of polarization-correlated photon pairs within 24 ns.

  20. Reconfigurable thz polarizer

    DEFF Research Database (Denmark)

    2016-01-01

    The present invention provides a polarizer. The polarizer comprises a first membrane having a first polarization region comprising a first plurality of membrane perforations; a second membrane having a second polarization region comprising a second plurality of membrane perforations; and a support...... with one or more membrane perforations in the second plurality of perforations in a direction normal to the first polarization region or normal to the second polarization region, resulting in corresponding one or more openings in said direction....

  1. Turn on Fluorescent Probes for Selective Targeting of Aldehydes

    Directory of Open Access Journals (Sweden)

    Ozlem Dilek

    2016-03-01

    Full Text Available Two different classes of fluorescent dyes were prepared as a turn off/on sensor system for aldehydes. Amino derivatives of a boron dipyrromethene (BDP fluorophore and a xanthene-derived fluorophore (rosamine were prepared. Model compounds of their product with an aldehyde were prepared using salicylaldehyde. Both amino boron dipyrromethene and rosamine derivatives are almost non-fluorescent in polar and apolar solvent. However, imine formation with salicylaldehyde on each fluorophore increases the fluorescence quantum yield by almost a factor of 10 (from 0.05 to 0.4. These fluorophores are therefore suitable candidates for development of fluorescence-based sensors for aldehydes.

  2. Protein conformation in solution by three-dimensional fluorescence spectrometry

    Institute of Scientific and Technical Information of China (English)

    鄢远; 许金钩; 陈国珍

    1996-01-01

    The conformations of bovine serum albumin (USA) and egg albumin (EA) in solution and their conformation changes under different conditions were studied by using three-dimensional fluorescence spectrometry (TDFS) such as three-dimensional fluorescence (TDF) spectra and three-dimensional fluorescence polarization (TDFP) spectra with tryptophan residues in protein molecules as an intrinsic fluorescent probe. The results show that the microenvironment of tryptophan residues of protein molecules in various solutions can be directly indicated and TDFS is an effective tool for studying protein conformation in solution. Meantime, some valuable results were obtained.

  3. Fluorescence of fullerene derivatives at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Lin, S.K.; Shiu, L.L.; Chien, K.M.; Luh, T.Y.; Lin, T.I. (National Taiwan Univ., Taipei (Taiwan, Province of China))

    1995-01-05

    The absorption and fluorescence spectral properties of fullerene (C[sub 60]) and its derivatives C[sub 60]C[sub 4]H[sub 6], C[sub 60]C[sub 5]H[sub 6], C[sub 60]CHCO[sub 2]Et, and C[sub 60]NCO[sub 2]Et at room temperature were investigated. Breaking the structural symmetry of C[sub 60] results in enhancing the fluorescence quantum yield 2-3-fold in some derivatives. Thus, the room temperature fluorescence of fullerene compounds could be detected more rapidly. New absorption bands and altered fluorescence spectra were observed in the derivatives. The Stokes' shifts of the derivatives are small, about 4-5 nm, compared to 68 nm for the parent compound. The time-resolved fluorescence decay study indicates that all four fullerene derivatives have a single fluorescence lifetime of ca. 1.2-1.4 as, which is about the same as that for C[sub 60] (ca. 1.3 ns). Aliphatic solvents have little influence on the absorption or fluorescence spectral profile except on the extinction coefficient whereas aromatic and polar solvents strongly interact with the fullerene derivatives, causing a peak broadening effect. 31 refs., 7 figs., 3 tabs.

  4. Polar and low polar solvents media effect on dipole moments of some diazo Sudan dyes.

    Science.gov (United States)

    Zakerhamidi, M S; Golghasemi Sorkhabi, Sh; Shamkhali, A N

    2014-06-05

    Absorption and fluorescence spectra of three Sudan dyes (SudanIII, SudanIV and Sudan black B) were recorded in various solvents with different polarity in the range of 300-800nm, at room temperature. The solvatochromic method was used to investigate dipole moments of these dyes in ground and excited states, in different media. The solvatochromic behavior of these substances and their solvent-solute interactions were analyzed via solvent polarity parameters. Obtained results express the effects of solvation on tautomerism and molecular configuration (geometry) of Sudan dyes in solvent media with different polarity. Furthermore, analyze of solvent-solute interactions and value of ground and excited states dipole moments suggests different forms of resonance structures for Sudan dyes in polar and low-polar solvents.

  5. Fundamentals of fluorescence and fluorescence microscopy.

    Science.gov (United States)

    Wolf, David E

    2013-01-01

    This chapter discusses the fundamental physics of fluorescence. The application of fluorescence to microscopy represents an important transition in the development of microscopy, particularly as it applies to biology. It enables quantitating the amounts of specific molecules within a cell, determining whether molecules are complexing on a molecular level, measuring changes in ionic concentrations within cells and organelles, and measuring molecular dynamics. This chapter also discusses the issues important to quantitative measurement of fluorescence and focuses on four of quantitative measurements of fluorescence--boxcar-gated detection, streak cameras, photon correlation, and phase modulation. Although quantitative measurement presents many pitfalls to the beginner, it also presents significant opportunities to one skilled in the art. This chapter also examines how fluorescence is measured in the steady state and time domain and how fluorescence is applied in the modern epifluorescence microscope.

  6. Optical modulator based on propagating surface plasmon coupled fluorescent thin film: proof-of-concept studies

    Science.gov (United States)

    Cao, Shuo-Hui; Wang, Zheng-Chuang; Weng, Yu-Hua; Xie, Kai-Xin; Chen, Min; Zhai, Yan-Yun; Li, Yao-Qun

    2017-06-01

    We demonstrate that the propagating surface plasmon coupled fluorescent thin film can be utilized as a fluorescence modulator to mimic multiple representative Boolean logic operations. Surface plasmon mediated fluorescence presents characteristic properties including directional and polarized emission, which hold the feasibility in creating a universal optical modulator. In this work, through constructing the thin layer with the specific thickness, surface plasmon mediated fluorescence can be modulated with an ON-OFF ratio by more than 5-fold, under a series of coupling configurations.

  7. Polarized Light in Astronomy.

    Science.gov (United States)

    King, D. J.

    1983-01-01

    The application of very sensitive electronic detecting devices during the last decade has revolutionized and revitalized the study of polarization in celestial objects. The nature of polarization, how polaroids work, interstellar polarization, dichroic filters, polarization by scattering, and modern polarimetry are among the topics discussed. (JN)

  8. Reviews in fluorescence 2010

    CERN Document Server

    Geddes, Chris D

    2011-01-01

    ""Reviews in Fluorescence 2010"", the seventh volume of the book serial from Springer, serves as a comprehensive collection of current trends and emerging hot topics in the field of fluorescence and closely related disciplines. It summarizes the year's progress in fluorescence and its applications, with authoritative analytical reviews specialized enough to be attractive to professional researchers, yet also appealing to the wider audience of scientists in related disciplines of fluorescence. ""Reviews in Fluorescence"" offers an essential reference material for any lab working in the fluoresc

  9. Principles of fluorescence techniques

    CERN Document Server

    2016-01-01

    Fluorescence techniques are being used and applied increasingly in academics and industry. The Principles of Fluorescence Techniques course will outline the basic concepts of fluorescence techniques and the successful utilization of the currently available commercial instrumentation. The course is designed for students who utilize fluorescence techniques and instrumentation and for researchers and industrial scientists who wish to deepen their knowledge of fluorescence applications. Key scientists in the field will deliver theoretical lectures. The lectures will be complemented by the direct utilization of steady-state and lifetime fluorescence instrumentation and confocal microscopy for FLIM and FRET applications provided by leading companies.

  10. Environment-sensitive fluorescent probe: a benzophosphole oxide with an electron-donating substituent.

    Science.gov (United States)

    Yamaguchi, Eriko; Wang, Chenguang; Fukazawa, Aiko; Taki, Masayasu; Sato, Yoshikatsu; Sasaki, Taeko; Ueda, Minako; Sasaki, Narie; Higashiyama, Tetsuya; Yamaguchi, Shigehiro

    2015-04-07

    Electron-donating aryl groups were attached to electron-accepting benzophosphole skeletons. Among several derivatives thus prepared, one benzophosphole oxide was particularly interesting, as it retained high fluorescence quantum yields even in polar and protic solvents. This phosphole-based compound exhibited a drastic color change of its fluorescence spectrum as a function of the solvent polarity, while the absorption spectra remained virtually unchanged. Capitalizing on these features, this phosphole-based compound was used to stain adipocytes, in which the polarity of subcellular compartments could then be discriminated on the basis of the color change of the fluorescence emission.

  11. Selective nonspecific solvation under dielectric saturation and fluorescence spectra of dye solutions in binary solvents.

    Science.gov (United States)

    Bakhshiev, N G; Kiselev, M B

    1991-09-01

    The influence of selective nonspecific solvation on the fluorescence spectra of three substitutedN-methylphthalimides in a binary solvent system consisting of a nonpolar (n-heptane) and a polar (pyridine) component has been studied under conditions close to dielectric saturation. The substantially nonlinearity of the effect is confirmation that the spectral shifts of fluorescence bands depend on the number of polar solvent molecules involved in solvating the dye molecule. The measured fluorescence spectral shifts determined by substituting one nonpolar solvent molecula with a polar one in the proximity of the dye molecule agree quantitatively with the forecasts of the previously proposed semiempirical theory which describes this nonlinear solvation phenomenon.

  12. Fluorescence correlation spectroscopy

    NARCIS (Netherlands)

    Hink, M.A.; Verveer, P.J.

    2015-01-01

    Fluorescence fluctuation spectroscopy techniques allow the quantification of fluorescent molecules present at the nanomolar concentration level. After a brief introduction to the technique, this chapter presents a protocol including background information in order to measure and quantify the molecul

  13. Safe biodegradable fluorescent particles

    Science.gov (United States)

    Martin, Sue I.; Fergenson, David P.; Srivastava, Abneesh; Bogan, Michael J.; Riot, Vincent J.; Frank, Matthias

    2010-08-24

    A human-safe fluorescence particle that can be used for fluorescence detection instruments or act as a safe simulant for mimicking the fluorescence properties of microorganisms. The particle comprises a non-biological carrier and natural fluorophores encapsulated in the non-biological carrier. By doping biodegradable-polymer drug delivery microspheres with natural or synthetic fluorophores, the desired fluorescence can be attained or biological organisms can be simulated without the associated risks and logistical difficulties of live microorganisms.

  14. Fluorescence anisotropy characterization of urine in the diagnosis of cancer

    Science.gov (United States)

    Rajasekaran, Ramu; Brindha, Elumalai; Sivabalan, Shanmugam; Aruna, Prakasa Rao; Koteeswaran, Dornadula; Ganesan, Singaravelu

    2016-03-01

    Cervical cancer is considered as the second most commonly occurring malignancy among women, next to breast cancer. It is well known that most of the cancer patients diagnosed with advanced stages and there is a pressing need for improved methods to detect cancer at its initial stages. Many techniques have been adopted for the diagnosis of cervical cancer. Among these, fluorescence polarization spectroscopy is a complementary technique of fluorescence spectroscopy which helps us to elucidate the spectral characteristics which highly depend on pH, viscosity and local environment. Since urine has many metabolites and the measurement of native fluorescence of urine, in principle, able to provide an indication of a number of health conditions, attempts were made to study fluorescence anisotropic characterization of the human urine of cervical cancer patients and normal subjects. Significant differences were observed between the anisotropic and polarization values of cancer subjects and normal subjects.

  15. WFPC2 Polarization Calibration

    Science.gov (United States)

    Biretta, J.; McMaster, M.

    1997-12-01

    We derive a detailed calibration for WFPC2 polarization data which is accurate to about 1.5%. We begin by computing polarizer flats, and show how they are applied to data. A physical model for the polarization effects of the WFPC2 optics is then created using Mueller matricies. This model includes corrections for the instrumental polarization (diattenuation and phase retardance) of the pick-off mirror, as well as the high cross-polarization transmission of the polarizer filter. We compare this model against the on-orbit observations of polarization calibrators, and show it predicts relative counts in the different polarizer/aperture settings to 1.5% RMS accuracy. We then show how this model can be used to calibrate GO data, and present two WWW tools which allow observers to easily calibrate their data. Detailed examples are given illustrationg the calibration and display of WFPC2 polarization data. In closing we describe future plans and possible improvements.

  16. Metasurface polarization splitter

    CERN Document Server

    Slovick, Brian A; Yu, Zhi Gang; Kravchenckou, Ivan I; Briggs, Dayrl P; Moitra, Parikshit; Krishnamurthy, Srini; Valentine, Jason

    2016-01-01

    Polarization beam splitters, devices that separate the two orthogonal polarizations of light into different propagation directions, are one of the most ubiquitous optical elements. However, traditionally polarization splitters rely on bulky optical materials, while emerging optoelectronic and photonic circuits require compact, chip-scale polarization splitters. Here we show that a subwavelength rectangular lattice of cylindrical silicon Mie resonators functions as a polarization splitter, efficiently reflecting one polarization while transmitting the other. We show that the polarization splitting arises from the anisotropic permittivity and permeability of the metasurface due to the two-fold rotational symmetry of the rectangular unit cell. The high polarization efficiency, low loss, and low profile make these metasurface polarization splitters ideally suited for monolithic integration with optoelectronic and photonic circuits.

  17. Monitoring membrane hydration with 2-(dimethylamino)-6-acylnaphtalenes fluorescent probes

    DEFF Research Database (Denmark)

    Bagatolli, Luis

    2015-01-01

    A family of polarity sensitive fluorescent probes (2-(dimethylamino)-6-acylnaphtalenes, i.e. LAURDAN, PRODAN, ACDAN) was introduced by Gregorio Weber in 1979, with the aim to monitor solvent relaxation phenomena on protein matrices. In the following years, however, PRODAN and particularly LAURDAN......, were used to study membrane lateral structure and associated dynamics. Once incorporated into membranes, the (nanosecond) fluorescent decay of these probes is strongly affected by changes in the local polarity and relaxation dynamics of restricted water molecules existing at the membrane/water...

  18. Polarized Electron Source Developments

    Energy Technology Data Exchange (ETDEWEB)

    Charles K. Sinclair

    1990-02-23

    Presently, only two methods of producing beams of polarized electrons for injection into linear accelerators are in use. Each of these methods uses optical pumping by circularly polarized light to produce electron polarization. In one case, electron polarization is established in metastable helium atoms, while in the other case, the polarized electrons are produced in the conduction band of appropriate semiconductors. The polarized electrons are liberated from the helium metastable by chemi-ionization, and from the semiconductors by lowering the work function at the surface of the material. Developments with each of these sources since the 1988 Spin Physics Conference are reviewed, and the prospects for further improvements discussed.

  19. Geographical Income Polarization

    DEFF Research Database (Denmark)

    Azhar, Hussain; Jonassen, Anders Bruun

    In this paper we estimate the degree, composition and development of geographical income polarization based on data at the individual and municipal level in Denmark from 1984 to 2002. Rising income polarization is reconfirmed when applying new polarization measures, the driving force being greater...... inter municipal income inequality. Counter factual simulations show that rising property prices to a large part explain the rise in polarization. One side-effect of polarization is tendencies towards a parallel polarization of residence location patterns, where low skilled individuals tend to live...

  20. 高效液相色谱法和荧光偏振免疫法检测血清万古霉素浓度的比较%Correlated research of detection for serum vancomycin concentrations between high performance liquid chromatography and fluorescence polarization immunoassay

    Institute of Scientific and Technical Information of China (English)

    黄进; 宋青; 张华峰; 肖健; 叶阳敏

    2013-01-01

    目的:比较高效液相色谱(HPLC)和荧光偏振免疫(FPIA)测定血清万古霉素浓度方法的相关性。方法30例患者的血清分别用HPLC和FPIA测定万古霉素浓度,对结果进行相关性分析。结果 HPLC测得万古霉素浓度为(30.04±14.02)μg/ml,FPIA测得值为(29.67±13.96)μg/ml,两种方法差值均值为(0.37±1.46)μg/ml,两种方法的线性相关系数r=0.9905。结论两种方法测定血清万古霉素药物浓度结果一致。%Objective The consistency of the results of serum vancomycin concentration the high-performance liquid chromatography (HPLC) and fluorescence polarization immunoassay (FPIA) were studied.Methods Serum vancomycin concentrations for 30 patients were measured by HPLC and FPIA. Correlation of results were analysised.Results Means for HPLC and standard deviation (SD) were (30.04±14.02)μg/ml. For FPIA,(29.67±13.96)μg/ml.The difference between the two methods’means were (0.37±1.46)μg/ml.The correlation coefficient of the two methods was 0.9905. Conclusion Measured serum vancomycin concentration results were consistent with each other.

  1. A physician's office-based digoxin assay (Seralyzer) evaluated for interference by endogenous digoxin-like immunoreactive factors.

    Science.gov (United States)

    Matheke, M L; Valdes, R

    1989-01-01

    A digoxin test for a physician's office based-chemistry analyzer (Ames Seralyzer) was evaluated for possible interference by digoxin-like immunoreactive factors (DLIF). Sera from patients likely to have high concentrations of DLIF (renal and hepatic patients, pregnant women, and neonates) as well as from normal patients and umbilical cord blood were analysed by the Seralyzer digoxin immunoassay and by a fluorescence polarization digoxin immunoassay (Abbott TDx) known to detect DLIF. For all patients who were not taking digoxin (n = 85) only four patients (4.7 percent) measured apparent digoxin values greater than 0.2 ng per mL by the Seralyzer compared to 64 (75 percent) by the TDx analyzer. Measurements of DLIF from adrenal extracts demonstrated a 17-fold greater potency for detection of DLIF by the TDx (2.9 ng per mL) compared to the Seralyzer technique (0.18 ng per mL). However, recovery data suggest that the presence of digoxin reduces the potency of DLIF interference as a function of increasing digoxin concentrations especially for the TDx assay. This diminished DLIF crossreactivity in the presence of digoxin is one explanation for the comparable correlation observed for both non-renal and renal failure patients taking digoxin when measured by these two immunoassays.

  2. Polarized Light Microscopy in Reproductive and Developmental Biology

    Science.gov (United States)

    KOIKE-TANI, MAKI; TANI, TOMOMI; MEHTA, SHALIN B.; VERMA, AMITABH; OLDENBOURG, RUDOLF

    2016-01-01

    SUMMARY The polarized light microscope reveals orientational order in native molecular structures inside living cells, tissues, and whole organisms. It is a powerful tool used to monitor and analyze the early developmental stages of organisms that lend themselves to microscopic observations. In this article, we briefly discuss the components specific to a traditional polarizing microscope and some historically important observations on: chromosome packing in the sperm head, the first zygote division of the sea urchin, and differentiation initiated by the first asymmetric cell division in the sand dollar. We then introduce the LC-PolScope and describe its use for measuring birefringence and polarized fluorescence in living cells and tissues. Applications range from the enucleation of mouse oocytes to analyzing the polarized fluorescence of the water strider acrosome. We end with new results on the birefringence of the developing chick brain, which we analyzed between developmental stages of days 12–20. PMID:23901032

  3. Optical-Fiber Fluorosensors With Polarized Light Sources

    Science.gov (United States)

    Egalon, Claudio O.; Rogowski, Robert S.

    1995-01-01

    Chemiluminescent and/or fluorescent molecules in optical-fiber fluorosensors oriented with light-emitting dipoles along transverse axis. Sensor of proposed type captures greater fraction of chemiluminescence or fluorescence and transmits it to photodetector. Transverse polarization increases sensitivity. Basic principles of optical-fiber fluorosensors described in "Making Optical-Fiber Chemical Sensors More Sensitive" (LAR-14525), "Improved Optical-Fiber Chemical Sensors" (LAR-14607), and "Improved Optical-Fiber Temperature Sensors" (LAR-14647).

  4. Optical-Fiber Fluorosensors With Polarized Light Sources

    Science.gov (United States)

    Egalon, Claudio O.; Rogowski, Robert S.

    1995-01-01

    Chemiluminescent and/or fluorescent molecules in optical-fiber fluorosensors oriented with light-emitting dipoles along transverse axis. Sensor of proposed type captures greater fraction of chemiluminescence or fluorescence and transmits it to photodetector. Transverse polarization increases sensitivity. Basic principles of optical-fiber fluorosensors described in "Making Optical-Fiber Chemical Sensors More Sensitive" (LAR-14525), "Improved Optical-Fiber Chemical Sensors" (LAR-14607), and "Improved Optical-Fiber Temperature Sensors" (LAR-14647).

  5. Proceedings of the Japan-US workshop on plasma polarization spectroscopy and the international seminar on plasma polarization spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fujimoto, Takashi; Beiersdorfer, Peter [eds.

    1998-06-01

    The international meeting on Plasma Polarization Spectroscopy (PPS) was held in Kyoto during January 26-28, 1998. This Proceedings book includes the papers of the talks given at the meeting. These include: overviews of PPS from the aspects of atomic physics, and of plasma physics; several PPS and MSE (motional Stark effect) experiments on magnetically confined plasmas and a laser-produced plasma; polarized laser-induced fluorescence spectroscopy, several experiments on EBITs (electron beam ion trap) and their theoretical interpretations; polarized profiles of spectral lines, basic formulation of PPS; inelastic and elastic electron collisions leading to polarized atomic states; polarization in recombining plasma; relationship between the collisional polarization relaxation and the line broadening; and characteristics of the plasma produced by very short pulse and high power laser irradiation. The 19 of the presented papers are indexed individually. (J.P.N.)

  6. A Translational Polarization Rotator

    CERN Document Server

    Chuss, David T; Pisano, Giampaolo; Ackiss, Sheridan; U-Yen, Kongpop; Ng, Ming wah

    2012-01-01

    We explore a free-space polarization modulator in which a variable phase introduction between right- and left-handed circular polarization components is used to rotate the linear polarization of the outgoing beam relative to that of the incoming beam. In this device, the polarization states are separated by a circular polarizer that consists of a quarter-wave plate in combination with a wire grid. A movable mirror is positioned behind and parallel to the circular polarizer. As the polarizer-mirror distance is separated, an incident linear polarization will be rotated through an angle that is proportional to the introduced phase delay. We demonstrate a prototype device that modulates Stokes Q and U over a 20% bandwidth.

  7. Polarized Light Corridor Demonstrations.

    Science.gov (United States)

    Davies, G. R.

    1990-01-01

    Eleven demonstrations of light polarization are presented. Each includes a brief description of the apparatus and the effect demonstrated. Illustrated are strain patterns, reflection, scattering, the Faraday Effect, interference, double refraction, the polarizing microscope, and optical activity. (CW)

  8. NESDIS VIIRS Polar Winds

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains the Level 3 Polar Winds Northern and Southern Hemisphere datasets. The Level 3 Polar Winds data from VIIRS for the Arctic and Antarctic from 65...

  9. Super-resolution quantum sensing using NV centers based on rotating linear polarized light and Monte-Carlo method

    CERN Document Server

    Zhang, Hua-Yu; Guo, Guang-Can; Sun, Fang-Wen

    2016-01-01

    The nitrogen vacancy (NV) center in diamond has been widely applied for quantum information and sensing in last decade. Based on the laser polarization dependent excitation of fluorescence emission, we propose a super-resolution microscopy of NV center. A series of wide field images of NV centers are taken with different polarizations of the linear polarized excitation laser. The fluorescence intensity of NV center is changed with the relative angle between excitation laser polarization and the orientation of NV center dipole. The images pumped by different excitation laser polarizations are analyzed with Monte Carlo method. Then the symmetry axis and position of NV center are obtained with sub-diffraction resolution.

  10. Plasma polarization spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fujimoto, Takashi [Department of Engineering Physics and Mechanics, Graduate School of Engineering, Kyoto University, Kyoto (Japan)

    2000-03-01

    Polarization of radiation emitted from a plasma reflects the anisotropic properties of the plasma, especially the angular anisotropic distribution of electron velocities. Polarization has been observed on impurity ion lines from the WT-3 tokamak and the GAMMA-10 tandem mirror machines. The soft x-ray laser line from the neonlike germanium was also found polarized. (author)

  11. Polarity at Many Levels

    Science.gov (United States)

    Flannery, Maura C.

    2004-01-01

    An attempt is made to find how polarity arises and is maintained, which is a central issue in development. It is a fundamental attribute of living things and cellular polarity is also important in the development of multicellular organisms and controversial new work indicates that polarization in mammals may occur much earlier than previously…

  12. Geographical Income Polarization

    DEFF Research Database (Denmark)

    Azhar, Hussain; Jonassen, Anders Bruun

    In this paper we estimate the degree, composition and development of geographical income polarization based on data at the individual and municipal level in Denmark from 1984 to 2002. Rising income polarization is reconfirmed when applying new polarization measures, the driving force being greater...

  13. Graphing Polar Curves

    Science.gov (United States)

    Lawes, Jonathan F.

    2013-01-01

    Graphing polar curves typically involves a combination of three traditional techniques, all of which can be time-consuming and tedious. However, an alternative method--graphing the polar function on a rectangular plane--simplifies graphing, increases student understanding of the polar coordinate system, and reinforces graphing techniques learned…

  14. Optical Control of Fluorescence through Plasmonic Eigenmode Extinction

    CERN Document Server

    Xu, Xiaoying; Li, Quanshui; Zhang, Zhili; Ivanov, Ilia N; Li, Yuan; Wang, Wenbin; Gu, Baohua; Zhang, Zhenyu; Hsueh, Chun-Hway; Snijders, Paul C; Seal, Katyayani

    2015-01-01

    We introduce the concept of optical control of the fluorescence yield of CdSe quantum dots through plasmon-induced structural changes in random semicontinuous nanostructured gold films. We demonstrate that the wavelength- and polarization dependent coupling between quantum dots and the semicontinuous films, and thus the fluorescent emission spectrum, can be controlled and significantly increased through the optical extinction of a selective band of eigenmodes in the films. This optical method of effecting controlled changes in the metal nanostructure allows for versatile functionality in a single sample and opens a pathway to in situ control over the fluorescence spectrum.

  15. Improvement of a polarized alkali ion source by means of optical pumping

    Energy Technology Data Exchange (ETDEWEB)

    Dreves, W.; Koch, E.; Jaensch, H.; Kamke, W.; Broermann, W.; Fick, D.

    1982-01-01

    A source for polarized alkali ions can be improved considerably by optical pumping of the atom beam in combination with a modified weak field transition. M-level populations were investigated using laser induced fluorescence in a magnetic field.

  16. Photoswitchable fluorescent diheteroarylethenes: substituent effects on photochromic and solvatochromic properties.

    Science.gov (United States)

    Gillanders, Florencia; Giordano, Luciana; Díaz, Sebastián A; Jovin, Thomas M; Jares-Erijman, Elizabeth A

    2014-03-01

    Photoswitchable fluorescent diheteroarylethenes are promising candidates for applications in super-resolution molecular localization fluorescence microscopy thanks to their high quantum yields and fatigue-resistant photoswitching characteristics. We have studied the effect of varying substituents on the photophysical properties of six sulfone derivatives of diheteroarylethenes, which display fluorescence in one (closed form) of two thermally stable photochromic states. Electron-donating substituents displace the absorption and emission spectra towards the red without substantially affecting the fluorescence quantum yields. Furthermore, ethoxybromo, a very electron-donating substituent, stabilizes the excited state of the closed isomer to the extent of almost entirely inhibiting its cycloreversion. Multi-parameter Hammett correlations indicate a relationship between the emission maxima and electron-donating character, providing a useful tool in the design of future photochromic molecules. Most of the synthesized compounds exhibit small bathochromic shifts and shorter fluorescence lifetimes with an increase in solvent polarity. However, the ethoxybromo-substituted fluorescent photochrome is unique in its strong solvatochromic behaviour, constituting a photoactivatable (photochromic), fluorescent and highly solvatochromic small organic compound. The Catalán formalism identified solvent dipolarity as the principal basis of the solvatochromism, reflecting the highly polarized nature of this molecule.

  17. Micro-environmental influences on the fluorescence of tryptophan

    Science.gov (United States)

    Sun, Feng; Zong, Wansong; Liu, Rutao; Chai, Jun; Liu, Ying

    2010-07-01

    The fluorescence characteristics of protein molecules are mainly due to their tryptophan (Trp), tyrosine (Tyr) and phenylalanine (Phe) residues, among which tryptophan is the most important. Studying the influence of the micro-environment on tryptophan fluorescence can give us direct and convincing evidence for changes of protein structure and function. In this paper, fluorescence spectroscopy was used to evaluate the changes of tryptophan fluorescence under a variety of micro-environmental conditions (temperature, pH, polarity, presence of surfactants and oxidants) and the mechanisms responsible. This study not only presents more direct evidence to explain how and why the protein fluorescence spectra change, but also provides a new method for analyzing the effect of environmental changes on protein function.

  18. Hepatoma polarization limits CD81 and hepatitis C virus dynamics.

    Science.gov (United States)

    Harris, H J; Clerte, C; Farquhar, M J; Goodall, M; Hu, K; Rassam, P; Dosset, P; Wilson, G K; Balfe, P; Ijzendoorn, S C; Milhiet, P E; McKeating, J A

    2013-03-01

    Many viruses target the polarized epithelial apex during host invasion. In contrast, hepatitis C virus (HCV) engages receptors at the basal surface of hepatocytes in the polarized liver parenchyma. Hepatocyte polarization limits HCV entry by undefined mechanism(s). Given the recent reports highlighting a role for receptor mobility in pathogen entry, we studied the effect(s) of hepatocyte polarization on viral receptor and HCV pseudoparticle (HCVpp) dynamics using real-time fluorescence recovery after photobleaching and single particle tracking. Hepatoma polarization reduced CD81 and HCVpp dynamics at the basal membrane. Since cell polarization is accompanied by changes in the actin cytoskeleton and CD81 links to actin via its C-terminus, we studied the dynamics of a mutant CD81 lacking a C-terminal tail (CD81(ΔC)) and its effect(s) on HCVpp mobility and infection. CD81(ΔC) showed an increased frequency of confined trajectories and a reduction of Brownian diffusing molecules compared to wild-type protein in non-polarized cells. However, these changes were notobserved in polarized cells. HCVpp showed a significant reduction in Brownian diffusion and infection of CD81(ΔC) expressing non-polarized cells. In summary, these data highlight the dynamic nature of CD81 and demonstrate a role for CD81 lateral diffusion to regulate HCV infection in a polarization-dependent manner.

  19. The Physics of Polarization

    Science.gov (United States)

    Landi Degl'Innocenti, Egidio

    2015-10-01

    The introductory lecture that has been delivered at this Symposium is a condensed version of an extended course held by the author at the XII Canary Island Winter School from November 13 to November 21, 2000. The full series of lectures can be found in Landi Degl'Innocenti (2002). The original reference is organized in 20 Sections that are here itemized: 1. Introduction, 2. Description of polarized radiation, 3. Polarization and optical devices: Jones calculus and Muller matrices, 4. The Fresnel equations, 5. Dichroism and anomalous dispersion, 6. Polarization in everyday life, 7. Polarization due to radiating charges, 8. The linear antenna, 9. Thomson scattering, 10. Rayleigh scattering, 11. A digression on Mie scattering, 12. Bremsstrahlung radiation, 13. Cyclotron radiation, 14. Synchrotron radiation, 15. Polarization in spectral lines, 16. Density matrix and atomic polarization, 17. Radiative transfer and statistical equilibrium equations, 18. The amplification condition in polarized radiative transfer, and 19. Coupling radiative transfer and statistical equilibrium equations.

  20. Polarization effects. Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    Courant, E.

    1981-01-01

    The use of polarized proton beams in ISABELLE is important for several general reasons: (1) With a single longitudinally polarized proton beam, effects involving parity violation can be identified and hence processes involving weak interactions can be separated from those involving strong and electromagnetic interactions. (2) Spin effects are important in the strong interactions and can be useful for testing QCD. The technique for obtaining polarized proton beams in ISABELLE appears promising, particularly in view of the present development of a polarized proton beam for the AGS. Projections for the luminosity in ISABELLE for collisions of polarized protons - one or both beams polarized with longitudinal or transverse polarization - range from 1/100 to 1 times the luminosity for unpolarized protons.

  1. Twisting Fluorescence through Extrinsic Chiral Antennas.

    Science.gov (United States)

    Yan, Chen; Wang, Xiaolong; Raziman, T V; Martin, Olivier J F

    2017-03-22

    Plasmonic antennas and planar structures have been undergoing intensive developments in order to control the scattering and absorption of light. One specific class, extrinsic chiral surfaces, that does not possess 2-fold rotational symmetry exhibits strong asymmetric transmission for different circular polarizations under obliquely incident illumination. In this work, we show that the design of those surfaces can be optimized with complex multipolar resonances in order to twist the fluorescence emission from nearby molecules. While this emission is usually dipolar and linearly polarized, the interaction with these resonances twists it into a multipolar radiation pattern with opposite helicity in different directions. The proposed structure maximizes this effect and provides control over the polarization of light. Splitting of left- and right-handed circularly polarized light is experimentally obtained in the backward direction. These results highlight the intricate interplay between the near-field absorption and the far-field scattering of a plasmonic nanostructure and are further used for modifying the emission of incoherent quantum sources. Our finding can potentially lead to the development of polarization- and angle-resolved ultracompact optical devices.

  2. Polarity inversion in polar-nonpolar-polar heterostructures.

    Science.gov (United States)

    Cho, S; Youn, S J; Kim, Y; DiVenere, A; Wong, G K; Freeman, A J; Ketterson, J B

    2001-09-17

    We have observed an epilayer-thickness-dependent polarity inversion for the growth of CdTe on Sb(Bi)/CdTe(111)B. For films with Sb(Bi) thicknesses of less than 40 A (15 A), the CdTe layer shows a B (Te-terminated) face, but it switches to an A (Cd-terminated) face for thicker layers. On the other hand, a CdTe layer grown on Bi(Sb)/CdTe(111)A always shows the A face regardless of Sb or Bi layer thicknesses. In order to address the observations we have performed ab initio calculations, which suggest that the polarity of a polar material on a nonpolar one results from the binding energy difference between the two possible surface configurations.

  3. Origin of tryptophan fluorescence lifetimes part 1. Fluorescence lifetimes origin of tryptophan free in solution.

    Science.gov (United States)

    Albani, J R

    2014-01-01

    Fluorescence intensity decays of L-tryptophan free in polar, hydrophobic and mixture of polar-hydrophobic solvents were recorded along the emission spectrum (310-410 nm). Analysis of the data show that emission of tryptophan occurs with two lifetimes in 100% polar and hydrophobic environments. The values of the two lifetimes are not the same in both environments while their populations (pre-exponentials values) are identical. Fluorescence lifetimes and pre-exponentials values do not change with the excitation wavelength and thus are independent of excitation energy. Our results indicate that tryptophan emission occurs from two specific sub-structures existing in the excited state. These sub-structures differ from those present in the ground states and characterize an internal property and/or organization of the tryptophan structure in the excited state. By sub-substructure, we mean here tryptophan backbone and its electronic cloud. In ethanol, three fluorescence lifetimes were measured; two lifetimes are very close to those observed in water (0.4-0.5 ns and 2-4 ns). Presence of a third lifetime for tryptophan in ethanol results from the interaction of both hydrophobic and hydrophilic dipoles or chemical functions of ethanol with the fluorophore.

  4. Device For Viewing Polarized Light

    Science.gov (United States)

    Noever, David A.

    1995-01-01

    Technique for detection of polarized light based on observation of scene through two stacked polarizing disks. No need to rotate polarizers to create flicker indicative of polarization. Implemented by relatively simple, lightweight apparatus. Polarization seen as bow-tie rainbow pattern. Advantageous for detecting polarization in variety of meteorological, geological, astronomical, and related applications.

  5. Solvent-dependent fluorescence enhancement and piezochromism of a carbazole-substituted naphthopyran

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Lihui; Wang, Aixia [Faculty of Chemistry, Northeast Normal University, Changchun 130024 (China); Wang, Guang, E-mail: wangg923@nenu.edu.cn [Faculty of Chemistry, Northeast Normal University, Changchun 130024 (China); Munyentwari, Alexis [Faculty of Chemistry, Northeast Normal University, Changchun 130024 (China); Zhou, Yihan, E-mail: yhzhou@ciac.ac.cn [National Analytical Research Center of Electrochemistry and Spectroscopy, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

    2015-09-15

    A novel carbazole-substituted naphthopyran, 3,3-bis-(4-carbazolylphenyl)-[3H]-naphtho[2,1-b]pyran (CzNP) was designed and synthesized. The new compound exhibited normal photochromism in dichloromethane solution and the UV irradiation did not influence its fluorescence. On the contrary, the fluorescence of CzNP in N,N-dimethylformamide (DMF) was intensively enhanced to 29 times after 60 min of the UV irradiation and this enhanced fluorescence can be quenched by addition of triethylamine (TEA). The study of enhanced extent of fluorescence of CzNP in solvents with different polarities and in mixed solvents demonstrated that the enhanced fluorescence is dependent on the polarity of solvents. The larger the polarity of solvent was, the stronger was the fluorescence of CzNP. CzNP also exhibited piezochromic performance and the pressure led to the cleavage of the C–O bond of pyran ring. - Highlights: • A carbazole-substituted photochromic naphthopyran was designed and synthesized. • The fluorescence was enhanced under the existence of DMF and UV irradiation. • The polarity of solvent was the dominating factor to affect the fluorescence. • The new compound also displayed piezochromic performance.

  6. Fluorescence spectroscopic studies of DNA dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Scalettar, B.A.

    1987-04-01

    Random solvent induced motions of DNA are manifest as nanosecond torsional oscillations of the helix backbone, nanosecond through millisecond bending deformations and overall rotational and translational diffusion of the polymer. Fluorescence spectroscopy is used to study this spectrum of DNA motions while ethidium monoazide was covalently bounded. The steady state fluorescence depolarization data indicate that the covalent monoazide/DNA complex exhibits internal motions characterized by an average angular amplitude of 26 degrees confirming reports of fast torsional oscillations in noncovalent ethidium bromide/DNA systems. Data obtained by use of a new polarized photobleaching recovery technique (FPR) reflect both the rotational dynamics of the polymer and the reversible photochemistry of the dye. To isolate the reorientational motion of the DNA, the FPR experiments were ran in two modes that differ only in the polarization of the bleaching light. A quotient function constructed from the data obtained in these two modes monitors only the rotational component of the FPR recovery. In specific applications those bending deformations of long DNA molecules that have characteristic relaxation times on the order of 100 microseconds have been resolved. A fluorescence correlation technique that relates fluctuations in particle number to center-of-mass motion was used to measure translational diffusion on coefficients of the plasmid PBR322 and a short oligomeric DNA. A theory that describes angular correlation in systems exhibiting cyclic, biologically directed reorientation and random Brownian rotation is developed.

  7. Analyzing planar cell polarity during zebrafish gastrulation.

    Science.gov (United States)

    Jessen, Jason R

    2012-01-01

    Planar cell polarity was first described in invertebrates over 20 years ago and is defined as the polarity of cells (and cell structures) within the plane of a tissue, such as an epithelium. Studies in the last 10 years have identified critical roles for vertebrate homologs of these planar cell polarity proteins during gastrulation cell movements. In zebrafish, the terms convergence and extension are used to describe the collection of morphogenetic movements and cell behaviors that contribute to narrowing and elongation of the embryonic body plan. Disruption of planar cell polarity gene function causes profound defects in convergence and extension creating an embryo that has a shortened anterior-posterior axis and is broadened mediolaterally. The zebrafish gastrula-stage embryo is transparent and amenable to live imaging using both Nomarski/differential interference contrast and fluorescence microscopy. This chapter describes methods to analyze convergence and extension movements at the cellular level and thereby connect embryonic phenotypes with underlying planar cell polarity defects in migrating cells.

  8. Restricted-access media high pressure liquid chromatography vs fluorescence polarization immunoassay for analysis of carbamazepine in human plasma%浸透限制固定相高压液相色谱法和荧光偏振免疫法测定人血中卡马西平浓度的比较

    Institute of Scientific and Technical Information of China (English)

    马骏; 朱彭龄; 谢景文; 贾正平; 杨金升

    2002-01-01

    目的:比较浸透限制固定相高效液相色谱法(RAM-HPLC)与荧光偏振免疫法(FPIA)测定人血中的卡马西平(CBZ)浓度.方法:建立一种直接进样RAM-HPLC法测定病人静脉和指端血浆的CBZ浓度.结果:两种测定方法都不需样品前处理,有好的重现性和近100%的回收率.FPIA测定静脉血样CBZ的结果与RAM-HPLC分别测定静脉和指端血样CBZ的结果有良好的相关性(R=0.989,0.995),但相差显著(P<0.05);而RAM-HPIC法测定静脉和指端血样两组数据间相差不显著(P>0.05).结论:RAM-HPLC和FPIA法均可测定CBZ浓度.在治疗药物监测中,FPIA更适合常规的监测;RAM-HPLC法更适用于相关研究和特殊病例监测,这里我们成功地应用于测定人外周微量血样中CBZ的浓度.%AIM: To compare restricted-access media high performance liquid chromatographic ( RAM-HPLC )method with fluorescence polarization immunoassay (FPIA) for analysis of carbamazepine (CBZ) in human blood. METHODS: An RAM-HPLC method was established for the determination of CBZ in plasma.RESULTS: The two methods do not need sample cleanup prior to analysis and they have almost 100 % recovery and good reprodtucibility. There is a good correlation between the CBZ concentration in venous plasma samples determined by FPIA and that in both venous and fingertip plasma samples obtained by RAM-HPLC, the correlation coefficients being 0.989 and 0.995, respectively. It is shown by t-test that the data sets of venous and fingertip plasma samples given by RAM-HPLC are consistent with each other but significantly different from the results obtained by FPIA. CONCLUSION: Both direct injection RAM-HPLC and FPIA may be applied in determining CBZ in therapeutic drug monitoring (TDM).FPIA is well-suited to the routine TDM. RAM-HPLC is more useful in TDM related research and especial cases.

  9. Fluorescence antibunching microscopy

    CERN Document Server

    Schwartz, Osip

    2011-01-01

    Breaking the diffraction limit in microscopy by utilizing quantum properties of light has been the goal of intense research in the recent years. We propose a quantum superresolution technique based on non-classical emission statistics of fluorescent markers, routinely used as contrast labels for bio-imaging. The technique can be readily implemented using standard fluorescence microscopy equipment.

  10. Fluorescence of atopic allergens

    NARCIS (Netherlands)

    Berrens, L.

    1967-01-01

    Purified atopic allergens have been found to emit flue fluorescence upon irradiation with ultraviolet light of 365 mμ wavelength. The maximum of fluorescence is in the region 445–490 mμ and the intensity is of the same order of magnitude for different atopic allergens. Synthetic model compounds, inc

  11. Fluorescent Lamp Replacement Study

    Science.gov (United States)

    2017-07-01

    Light-emitting diode, LED, lighting, fluorescent, waste reduction, energy conservation, net zero , mercury 16. SECURITY CLASSIFICATION OF: 17. LIMITATION...Center (ATC) to assess the benefits of converting fluorescent tube lighting to light-emitting diode (LED) technology. The report documents the waste ...1-15 SECTION 2. SUBTESTS 2.1 HAZARDOUS WASTE REDUCTION

  12. LEDs for fluorescence microscopy

    NARCIS (Netherlands)

    Young, I.T.; Garini, Y.; Dietrich, H.R.C.; Van Oel, W.; Liqui Lung, G.

    2004-01-01

    Traditional light sources for fluorescence microscopy have been mercury lamps, xenon lamps, and lasers. These sources have been essential in the development of fluorescence microscopy but each can have serious disadvantages: lack of near monochromaticity, heat generation, cost, lifetime of the light

  13. A STUDY ON THE PROPERTIES OF MICELLE FORMED BY ANIONIC AQUEOUS POLYURETHANE DISPERSION WITH FLUORESCENT PROBE METHOD%荧光探针法研究聚氨酯水分散液的胶束性质

    Institute of Scientific and Technical Information of China (English)

    刘剑洪; 刘冬; 任祥忠; 田德余

    2001-01-01

    Pyrene was used as a fluorescent probe to investigate the polarity and stability of the micelle of anionic aqueous polyurethane dispersion(AAPUD).Results indicated that the micelle is non-polar or weak polar,and the polarity is greatly dependent on the hydrophilicity of the main chain of polyurethane and the pH value of the medium.The polarized value of the polarized fluorescent of pyrene in the AAPUD was measured, and the results show that the stability of the micelle could be characterized by the polarized value.

  14. Contrasting solvent polarity effect on the photophysical properties of two newly synthesized aminostyryl dyes in the lower and in the higher solvent polarity regions.

    Science.gov (United States)

    Shaikh, M; Mohanty, J; Singh, P K; Bhasikuttan, A C; Rajule, R N; Satam, V S; Bendre, S R; Kanetkar, V R; Pal, H

    2010-04-08

    Solvent polarity effect on the photophysical properties of two newly synthesized aminostyryl-thiazoloquinoxaline dyes, one with a flexible diphenylamino group, namely, N,N-diphenyl-4-[2-(thiazolo[4,5-b]quinoxalin-2-yl)vinyl]aniline (TQ1), and the other with a rigid julolidinylamino group, namely, (9-[2-(thiazolo[4,5-b]quinoxalin-2-yl)vinyl]julolidine) (TQ2), have been investigated in different aprotic solvents and solvent mixtures. From the polarity dependent changes in the absorption and fluorescence spectral properties, it is indicated that the fluorescent states of the dyes are of intramolecular charge transfer (ICT) character. For both the dyes, the photophysical properties like fluorescence quantum yields (Phi(f)), fluorescence lifetimes (tau(f)), radiative rate constants (k(f) = Phi(f)/tau(f)), and nonradiative rate constants (k(nr) = 1/tau(f) - Phi(f)/tau(f)) show clearly contrasting solvent polarity effects in the lower and in the higher solvent polarity region, causing an interesting reversal in the properties below and above an intermediate solvent polarity. It is inferred that the domination of the cis-trans isomerization in the lower solvent polarity region and that of the twisted intramolecular charge transfer (TICT) state formation in the higher solvent polarity region are responsible for the observed contrasting solvent polarity effects on the photophysical properties of the two dyes. As both isomerization and TICT state formation causes an enhancement in the nonradiative decay rate of the excited dyes and both the processes become less significant at the intermediate solvent polarity region, the two dyes show their largest Phi(f) and tau(f) values at intermediate solvent polarities. Suitable mechanistic schemes have been proposed and qualitative potential energy diagrams have been presented to explain the observed results with the changes in the polarity of the solvents used.

  15. Angle-resolved polarimetry measurements of antenna-mediated fluorescence

    CERN Document Server

    Mohtashami, Abbas; Koenderink, A Femius

    2015-01-01

    Optical phase-array antennas can be used to control not only the angular distribution but also the polarization of fluorescence from quantum emitters. The emission pattern of the resulting system is determined by the properties of the antenna, the properties of the emitters and the strength of the antenna-emitter coupling. Here we show that Fourier polarimetry can be used to characterize these three contributions. To this end, we measured the angle and Stokes-parameter resolved emission of bullseye plasmon antennas as well as spiral antennas excited by an ensemble of emitters. We estimate the antenna-emitter coupling on basis of the degree of polarization, and determine the effect of anisotropy in the intrinsic emitter orientation on polarization of the resulting emission pattern. Our results not only provide new insights in the behavior of bullseye and spiral antennas, but also demonstrate the potential of Fourier polarimetry when characterizing antenna mediated fluorescence.

  16. Fluorescence characteristics of aryl boronic acid derivate (PBA)

    Science.gov (United States)

    Patil, S. S.; Muddapur, G. V.; Patil, N. R.; Melavanki, R. M.; Kusanur, R. A.

    2015-03-01

    The absorption and fluorescence spectra of newly synthesized aryl boronic acid derivative namely Phenyl boronic acid (PBA) have been recorded in various solvents of different polarities. The ground state dipole moment of PBA was obtained from quantum chemical calculations. Solvatochromic correlations were used to estimate the ground state (μg) and excited state (μe) dipole moments. The excited state dipole moments are observed to be greater than the ground state dipole moments. Further, the ground and excited state dipole moments are not parallel but subtend by an angle of 70°. The changes in dipole moment (Δμ) were calculated both from solvatochromic shift method and microscopic solvent polarity parameter (ETN), and the values are compared. Solvent effects on the absorption and fluorescence spectra were quantified using Reichardt's and bulk solvent polarity parameters were complemented by the results of the Kamlet-Taft treatment.

  17. The Mechanisms and Biomedical Applications of an NIR BODIPY-Based Switchable Fluorescent Probe

    Directory of Open Access Journals (Sweden)

    Bingbing Cheng

    2017-02-01

    Full Text Available Highly environment-sensitive fluorophores have been desired for many biomedical applications. Because of the noninvasive operation, high sensitivity, and high specificity to the microenvironment change, they can be used as excellent probes for fluorescence sensing/imaging, cell tracking/imaging, molecular imaging for cancer, and so on (i.e., polarity, viscosity, temperature, or pH measurement. In this work, investigations of the switching mechanism of a recently reported near-infrared environment-sensitive fluorophore, ADP(CA2, were conducted. Besides, multiple potential biomedical applications of this switchable fluorescent probe have been demonstrated, including wash-free live-cell fluorescence imaging, in vivo tissue fluorescence imaging, temperature sensing, and ultrasound-switchable fluorescence (USF imaging. The fluorescence of the ADP(CA2 is extremely sensitive to the microenvironment, especially polarity and viscosity. Our investigations showed that the fluorescence of ADP(CA2 can be switched on by low polarity, high viscosity, or the presence of protein and surfactants. In wash-free live-cell imaging, the fluorescence of ADP(CA2 inside cells was found much brighter than the dye-containing medium and was retained for at least two days. In all of the fluorescence imaging applications conducted in this study, high target-to-noise (>5-fold was achieved. In addition, a high temperature sensitivity (73-fold per Celsius degree of ADP(CA2-based temperature probes was found in temperature sensing.

  18. The Mechanisms and Biomedical Applications of an NIR BODIPY-Based Switchable Fluorescent Probe.

    Science.gov (United States)

    Cheng, Bingbing; Bandi, Venugopal; Yu, Shuai; D'Souza, Francis; Nguyen, Kytai T; Hong, Yi; Tang, Liping; Yuan, Baohong

    2017-02-11

    Highly environment-sensitive fluorophores have been desired for many biomedical applications. Because of the noninvasive operation, high sensitivity, and high specificity to the microenvironment change, they can be used as excellent probes for fluorescence sensing/imaging, cell tracking/imaging, molecular imaging for cancer, and so on (i.e., polarity, viscosity, temperature, or pH measurement). In this work, investigations of the switching mechanism of a recently reported near-infrared environment-sensitive fluorophore, ADP(CA)₂, were conducted. Besides, multiple potential biomedical applications of this switchable fluorescent probe have been demonstrated, including wash-free live-cell fluorescence imaging, in vivo tissue fluorescence imaging, temperature sensing, and ultrasound-switchable fluorescence (USF) imaging. The fluorescence of the ADP(CA)₂ is extremely sensitive to the microenvironment, especially polarity and viscosity. Our investigations showed that the fluorescence of ADP(CA)₂ can be switched on by low polarity, high viscosity, or the presence of protein and surfactants. In wash-free live-cell imaging, the fluorescence of ADP(CA)₂ inside cells was found much brighter than the dye-containing medium and was retained for at least two days. In all of the fluorescence imaging applications conducted in this study, high target-to-noise (>5-fold) was achieved. In addition, a high temperature sensitivity (73-fold per Celsius degree) of ADP(CA)₂-based temperature probes was found in temperature sensing.

  19. The Mechanisms and Biomedical Applications of an NIR BODIPY-Based Switchable Fluorescent Probe

    Science.gov (United States)

    Cheng, Bingbing; Bandi, Venugopal; Yu, Shuai; D’Souza, Francis; Nguyen, Kytai T.; Hong, Yi; Tang, Liping; Yuan, Baohong

    2017-01-01

    Highly environment-sensitive fluorophores have been desired for many biomedical applications. Because of the noninvasive operation, high sensitivity, and high specificity to the microenvironment change, they can be used as excellent probes for fluorescence sensing/imaging, cell tracking/imaging, molecular imaging for cancer, and so on (i.e., polarity, viscosity, temperature, or pH measurement). In this work, investigations of the switching mechanism of a recently reported near-infrared environment-sensitive fluorophore, ADP(CA)2, were conducted. Besides, multiple potential biomedical applications of this switchable fluorescent probe have been demonstrated, including wash-free live-cell fluorescence imaging, in vivo tissue fluorescence imaging, temperature sensing, and ultrasound-switchable fluorescence (USF) imaging. The fluorescence of the ADP(CA)2 is extremely sensitive to the microenvironment, especially polarity and viscosity. Our investigations showed that the fluorescence of ADP(CA)2 can be switched on by low polarity, high viscosity, or the presence of protein and surfactants. In wash-free live-cell imaging, the fluorescence of ADP(CA)2 inside cells was found much brighter than the dye-containing medium and was retained for at least two days. In all of the fluorescence imaging applications conducted in this study, high target-to-noise (>5-fold) was achieved. In addition, a high temperature sensitivity (73-fold per Celsius degree) of ADP(CA)2-based temperature probes was found in temperature sensing. PMID:28208666

  20. Polar varieties revisited

    OpenAIRE

    Piene, Ragni

    2016-01-01

    We recall the definition of classical polar varieties, as well as those of affine and projective reciprocal polar varieties. The latter are defined with respect to a non-degenerate quadric, which gives us a notion of orthogonality. In particular we relate the reciprocal polar varieties to the "Euclidean geometry" in projective space. The Euclidean distance degree and the degree of the focal loci can be expressed in terms of the ranks, i.e., the degrees of the classical polar varieties, and he...

  1. Polarization at SLC

    Energy Technology Data Exchange (ETDEWEB)

    Swartz, M.L.

    1988-07-01

    The SLAC Linear Collider has been designed to readily accommodate polarized electron beams. Considerable effort has been made to implement a polarized source, a spin rotation system, and a system to monitor the beam polarization. Nearly all major components have been fabricated. At the current time, several source and polarimeter components have been installed. The installation and commissioning of the entire system will take place during available machine shutdown periods as the commissioning of SLC progresses. It is expected that a beam polarization of 45% will be achieved with no loss in luminosity. 13 refs., 15 figs.

  2. Polarized negative ions

    Energy Technology Data Exchange (ETDEWEB)

    Haeberli, W.

    1981-04-01

    This paper presents a survey of methods, commonly in use or under development, to produce beams of polarized negative ions for injection into accelerators. A short summary recalls how the hyperfine interaction is used to obtain nuclear polarization in beams of atoms. Atomic-beam sources for light ions are discussed. If the best presently known techniques are incorporated in all stages of the source, polarized H/sup -/ and D/sup -/ beams in excess of 10 ..mu..A can probably be achieved. Production of polarized ions from fast (keV) beams of polarized atoms is treated separately for atoms in the H(25) excited state (Lamb-Shift source) and atoms in the H(1S) ground state. The negative ion beam from Lamb-Shift sources has reached a plateau just above 1 ..mu..A, but this beam current is adequate for many applications and the somewhat lower beam current is compensated by other desirable characteristics. Sources using fast polarized ground state atoms are in a stage of intense development. The next sections summarize production of polarized heavy ions by the atomic beam method, which is well established, and by optical pumping, which has recently been demonstrated to yield very large nuclear polarization. A short discussion of proposed ion sources for polarized /sup 3/He/sup -/ ions is followed by some concluding remarks.

  3. Influence of matrix effect upon cyclosporine A test by fluorescence polarization immunoassay and enzyme-multiplied immunoassay technique methods%基质效应对荧光偏振免疫测定技术和酶放大免疫测定方法检测环孢素A结果的影响

    Institute of Scientific and Technical Information of China (English)

    顾志冬; 陈皓; 周佩军; 冯晓静; 林孝怡; 徐达; 樊绮诗

    2009-01-01

    Objective To explore the matrix effect on cyclosporine A (CsA) test by fluorescence polarization immunoassay (FPIA) and enzyme-multiplied immunoassay technique (EMIT), explain the discrepancy of external quality control results between these two methods and find the corrective action.Methods One hundred whole blood samples with various concentrations were adopted and CsA levels were detected by FPIA and EMIT.The results were compared with each other.Moreover, the influence of residual metal ions upon immunoreactions was assessed by adding Cu2+ and Zn2+.The effect of non-whole blood matrix on extraction efficiency for quality control materials and CsA calibrator was evaluated by adding identical volume of Hb-rich reagents followed with re-extraction.Results There is good correlation between results measured with FPIA(X) and EMIT(Y) methods ( Y=0.926 8X -8.115,R2 =0.996 9).Neither FPIA nor EMIT was affected by residual metal ions ( P > 0.05 ). Non-whole blood matrix decreased the extraction efficiency of two methods, but it could be corrected by supplementation of the Hb-rich reagents (≥30 g/L).Conclusions Non-whole blood matrix may be the main reason for the inconsistent results measured by FPIA and EMIT methods.It could be corrected by using Hb-rich reagents.In addition,we should consider the influence of low lib on CsA test,espocially for organ transplant patients with lower Hb ( <30 g/L).%目的 通过荧光偏振免疫测定(fluorescence polarization immunoassay,FPIA)和酶放大免疫测定技术(enzyme-multiplied immunoassay technique,EMIT)测定环孢素A(cyciosporine,CsA),了解基质效应对检测结果的影响,解释在CsA室问质评结果中两方法的检测结果的差别,并找到纠正方法.方法 选择不同浓度的临床全血标本100份,用FPIA和EMIT技术进行检测,对比检测结果;通过添加Cu2+,zn2+评估离子残留对免疫反应的影响;用添加等体积血红蛋白富集液后再次抽提的方法,

  4. Fluorescence and Spectral Imaging

    Directory of Open Access Journals (Sweden)

    Ralph S. DaCosta

    2007-01-01

    Full Text Available Early identification of dysplasia remains a critical goal for diagnostic endoscopy since early discovery directly improves patient survival because it allows endoscopic or surgical intervention with disease localized without lymph node involvement. Clinical studies have successfully used tissue autofluorescence with conventional white light endoscopy and biopsy for detecting adenomatous colonic polyps, differentiating benign hyperplastic from adenomas with acceptable sensitivity and specificity. In Barrett's esophagus, the detection of dysplasia remains problematic because of background inflammation, whereas in the squamous esophagus, autofluorescence imaging appears to be more dependable. Point fluorescence spectroscopy, although playing a crucial role in the pioneering mechanistic development of fluorescence endoscopic imaging, does not seem to have a current function in endoscopy because of its nontargeted sampling and suboptimal sensitivity and specificity. Other point spectroscopic modalities, such as Raman spectroscopy and elastic light scattering, continue to be evaluated in clinical studies, but still suffer the significant disadvantages of being random and nonimaging. A recent addition to the fluorescence endoscopic imaging arsenal is the use of confocal fluorescence endomicroscopy, which provides real-time optical biopsy for the first time. To improve detection of dysplasia in the gastrointestinal tract, a new and exciting development has been the use of exogenous fluorescence contrast probes that specifically target a variety of disease-related cellular biomarkers using conventional fluorescent dyes and novel potent fluorescent nanocrystals (i.e., quantum dots. This is an area of great promise, but still in its infancy, and preclinical studies are currently under way.

  5. Introduction to fluorescence probing of biological membranes.

    Science.gov (United States)

    Demchenko, Alexander P; Duportail, Guy; Oncul, Sule; Klymchenko, Andrey S; Mély, Yves

    2015-01-01

    Fluorescence is one of the most powerful and commonly used tools in biophysical studies of biomembrane structure and dynamics that can be applied on different levels, from lipid monolayers and bilayers to living cells, tissues, and whole animals. Successful application of this method relies on proper design of fluorescence probes with optimized photophysical properties. These probes are efficient for studying the microscopic analogs of viscosity, polarity, and hydration, as well as the molecular order, environment relaxation, and electrostatic potentials at the sites of their location. Being smaller than the membrane width they can sense the gradients of these parameters across the membrane. We present examples of novel dyes that achieve increased spatial resolution and information content of the probe responses. In this respect, multiparametric environment-sensitive probes feature considerable promise.

  6. A cutin fluorescence pattern in developing embryos of some angiosperms

    Directory of Open Access Journals (Sweden)

    Ewa Szczuka

    2014-01-01

    Full Text Available A cuticle visualized by auramine O fluorescence appears on the developing embryos of 9 species belonging to Cruciferae, Caryophyllaceae, Plantaginaceae, Linaceae and Papilionaceae. In the investigated species the formation and extent of fluorescing and non-fluorescing embryonic areas follow a similar pattern. At first the cutin fluorescing layer is formed on the apical part of the proembryo without delimited protoderm. This layer extends and at the late globular stage envelops the embryo proper, except for a cell adjoining the suspensor. Fluorescing cutin persists during the heart stage but disappears from the torpedo embryo. During these stages there is no cutine fluorescence on suspensorial cells. Continuous cutin fluorescence appears again on the surface of the whole embryo by the late torpedo stage. Then fluorescence disappears from the radicular part of U-shaped embryos, but persists on the shoot apex, cotyledons and at least on the upper part of hypocotyl. It is assumed that polarization and nutrition of the embryo may be influenced by cuticular changes.

  7. Highly thermostable fluorescent proteins

    Science.gov (United States)

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

    2012-05-01

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

  8. Highly thermostable fluorescent proteins

    Science.gov (United States)

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

    2011-03-22

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

  9. RHIC Polarized proton operation

    Energy Technology Data Exchange (ETDEWEB)

    Huang, H.; Ahrens, L.; Alekseev, I.G.; Aschenauer, E.; Atoian, G.; Bai, M.; Bazilevsky, A.; Blaskiewicz, M.; Brennan, J.M.; Brown, K.A.; Bruno, D.; Connolly, R.; Dion, A.; D' Ottavio, T.; Drees, K.A.; Fischer, W.; Gardner, C.; Glenn, J.W.; Gu, X.; Harvey, M.; Hayes, T.; Hoff, L.; Hulsart, R.L.; Laster, J.; Liu, C.; Luo, Y.; MacKay, W.W.; Makdisi, Y.; Marr, G.J.; Marusic, A.; Meot, F.; Mernick, K.; Michnoff, R,; Minty, M.; Montag, C.; Morris, J.; Nemesure, S.; Poblaguev, A.; Ptitsyn, V.; Ranjibar, V.; Robert-Demolaize, G.; Roser, T.; J.; Severino, F.; Schmidke, B.; Schoefer, V.; Severino, F.; Smirnov, D.; Smith, K.; Steski, D.; Svirida, D.; Tepikian, S.; Trbojevic, D.; Tsoupas, N.; Tuozzolo, J. Wang, G.; Wilinski, M.; Yip, K.; Zaltsman, A.; Zelenski, A.; Zeno, K.; Zhang, S.Y.

    2011-03-28

    The Relativistic Heavy Ion Collider (RHIC) operation as the polarized proton collider presents unique challenges since both luminosity(L) and spin polarization(P) are important. With longitudinally polarized beams at the experiments, the figure of merit is LP{sup 4}. A lot of upgrades and modifications have been made since last polarized proton operation. A 9 MHz rf system is installed to improve longitudinal match at injection and to increase luminosity. The beam dump was upgraded to increase bunch intensity. A vertical survey of RHIC was performed before the run to get better magnet alignment. The orbit control is also improved this year. Additional efforts are put in to improve source polarization and AGS polarization transfer efficiency. To preserve polarization on the ramp, a new working point is chosen such that the vertical tune is near a third order resonance. The overview of the changes and the operation results are presented in this paper. Siberian snakes are essential tools to preserve polarization when accelerating polarized beams to higher energy. At the same time, the higher order resonances still can cause polarization loss. As seen in RHIC, the betatron tune has to be carefully set and maintained on the ramp and during the store to avoid polarization loss. In addition, the orbit control is also critical to preserve polarization. The higher polarization during this run comes from several improvements over last run. First we have a much better orbit on the ramp. The orbit feedback brings down the vertical rms orbit error to 0.1mm, much better than the 0.5mm last run. With correct BPM offset and vertical realignment, this rms orbit error is indeed small. Second, the jump quads in the AGS improved input polarization for RHIC. Third, the vertical tune was pushed further away from 7/10 snake resonance. The tune feedback maintained the tune at the desired value through the ramp. To calibrate the analyzing power of RHIC polarimeters at any energy above

  10. Plasma polarization spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Iwamae, Atsushi; Inoue, Takeru; Tanaka, Akihiro; Kawakami, Kazuki; Fujimoto, Takashi [Kyoto Univ., Dept. of Engineering Physics, Kyoto (Japan)

    2000-03-01

    Polarization of radiation emitted from plasma reflects the anisotropic properties of the plasma, especially the angular isotropic distribution of electron velocities. Polarization has been observed on impurity ion lines from the WT-3 tokamak and GAMMA 10 tandem mirror device. (author)

  11. Planetary polarization nephelometer

    NARCIS (Netherlands)

    Banfield, D.; Dissly, R.; Mishchenko, M.; Muñoz, O.; Roos-Serote, M.; Stam, D.M.; Volten, H.; Wilson, A.

    2004-01-01

    We have proposed to develop a polarization nephelometer for use on future planetary descent probes. It will measure both the scattered intensity and polarization phase functions of the aerosols it encounters descending through an atmosphere. These measurements will be taken at two wavelengths

  12. Polar Cap Patch Dynamics

    Science.gov (United States)

    2013-04-25

    cap arcs Citation: Hosokawa, K., J. I. Moen, K. Shiokawa, and Y. Otsuka ( 2011 ), Motion of polar cap arcs , J. Geophys. Res. , 116 , A01305, doi...K., J. I. Moen, K. Shiokawa, and Y. Otsuka , (2011), Decay of polar cap patch, J. Geophys. Res., 116, A05308, doi:10.1029/2010JA016287, Abstract. We

  13. Polar Code Validation

    Science.gov (United States)

    1989-09-30

    SUMMARY OF POLAR ACHIEVEMENTS ..... .......... 3 3. POLAR CODE PHYSICAL MODELS ..... ............. 5 3.1 PL- ASMA Su ^"ru5 I1LS SH A...of this problem. 1.1. The Charge-2 Rocket The Charge-2 payload was launched on a Black Brant VB from White Sands Mis- sile Range in New Mexico in

  14. Polarization modulators for CMBPol

    Energy Technology Data Exchange (ETDEWEB)

    Ade, P A R; Savini, G [Cardiff University, School of Physics and Astronomy, Queens Buildings, The Parade, Cardiff, CF24 3AA (United Kingdom); Chuss, D T [NASA Goddard Space Flight Center, Code 665, Greenbelt, MD, 20771 (United States); Hanany, S [School of Physics and Astronomy, University of Minnesota/Twin Cities, Minneapolis, MN, 55455 (United States); Haynes, V; Pisano, G [University of Manchester, School of Physics and Astronomy - Alan Turing Building, Upper Brooke street, Manchester, M13 4PL (United Kingdom); Keating, B G [Department of Physics, University of California, San Diego, La Jolla, CA 92093-0424 (United States); Kogut, A [Code 665 Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Ruhl, J E [Physics Department, Case Western Reserve University, Cleveland, OH, 44106 (United States); Wollack, E J [Observational Cosmology Laboratory, NASA/GSFC, Greenbelt, MD 20771 (United States)

    2009-03-01

    We review a number of technologies that are candidates for active polarization modulators for CMBPol. The technologies are appropriate for instruments that use bolometric detectors and include birefringent crystal-based and metal-mesh-based half-wave plates, variable phase polarization modulator, Faraday rotator, and photolithographed modulators. We also give a current account of the status of millimeter-wave orthomode transducers.

  15. Polarized Light: Three Demonstrations.

    Science.gov (United States)

    Goehmann, Ruth; Welty, Scott

    1984-01-01

    Describes three demonstrations used in the Chicago Museum of Science and Industry polarized light show. The procedures employed are suitable for the classroom by using smaller polarizers and an overhead projector. Topic areas include properties of cellophane tape, nondisappearing arrows, and rope through a picket fence. (JN)

  16. Planetary polarization nephelometer

    NARCIS (Netherlands)

    Banfield, D.; Dissly, R.; Mishchenko, M.; Muñoz, O.; Roos-Serote, M.; Stam, D.M.; Volten, H.; Wilson, A.

    2004-01-01

    We have proposed to develop a polarization nephelometer for use on future planetary descent probes. It will measure both the scattered intensity and polarization phase functions of the aerosols it encounters descending through an atmosphere. These measurements will be taken at two wavelengths separa

  17. Our Polar Past

    Science.gov (United States)

    Clary, Renee; Wandersee, James

    2009-01-01

    The study of polar exploration is fascinating and offers students insights into the history, culture, and politics that affect the developing sciences at the farthest ends of Earth. Therefore, the authors think there is value in incorporating polar exploration accounts within modern science classrooms, and so they conducted research to test their…

  18. Polarized Light: Three Demonstrations.

    Science.gov (United States)

    Goehmann, Ruth; Welty, Scott

    1984-01-01

    Describes three demonstrations used in the Chicago Museum of Science and Industry polarized light show. The procedures employed are suitable for the classroom by using smaller polarizers and an overhead projector. Topic areas include properties of cellophane tape, nondisappearing arrows, and rope through a picket fence. (JN)

  19. Polarization sensitive localization based super-resolution microscopy with a birefringent wedge

    Science.gov (United States)

    Sinkó, József; Gajdos, Tamás; Czvik, Elvira; Szabó, Gábor; Erdélyi, Miklós

    2017-03-01

    A practical method has been presented for polarization sensitive localization based super-resolution microscopy using a birefringent dual wedge. The measurement of the polarization degree at the single molecule level can reveal the chemical and physical properties of the local environment of the fluorescent dye molecule and can hence provide information about the sub-diffraction sized structure of biological samples. Polarization sensitive STORM imaging of the F-Actins proved correlation between the orientation of fluorescent dipoles and the axis of the fibril.

  20. Nomenclature of polarized light - Elliptical polarization

    Science.gov (United States)

    Clarke, D.

    1974-01-01

    Alternative handedness and sign conventions for relating the orientation of elliptical polarization are discussed. The discussion proceeds under two headings: (1) snapshot picture, where the emphasis for the convention is contained in the concept of handedness; and (2) angular momentum consideration, where the emphasis for the convention is strongly associated with mathematical convention and the sign of the fourth Stokes parameter.

  1. Parallel Polarization State Generation

    Science.gov (United States)

    She, Alan; Capasso, Federico

    2016-05-01

    The control of polarization, an essential property of light, is of wide scientific and technological interest. The general problem of generating arbitrary time-varying states of polarization (SOP) has always been mathematically formulated by a series of linear transformations, i.e. a product of matrices, imposing a serial architecture. Here we show a parallel architecture described by a sum of matrices. The theory is experimentally demonstrated by modulating spatially-separated polarization components of a laser using a digital micromirror device that are subsequently beam combined. This method greatly expands the parameter space for engineering devices that control polarization. Consequently, performance characteristics, such as speed, stability, and spectral range, are entirely dictated by the technologies of optical intensity modulation, including absorption, reflection, emission, and scattering. This opens up important prospects for polarization state generation (PSG) with unique performance characteristics with applications in spectroscopic ellipsometry, spectropolarimetry, communications, imaging, and security.

  2. Parallel Polarization State Generation

    CERN Document Server

    She, Alan

    2016-01-01

    The control of polarization, an essential property of light, is of wide scientific and technological interest. The general problem of generating arbitrary time-varying states of polarization (SOP) has always been mathematically formulated by a series of linear transformations, i.e. a product of matrices, imposing a serial architecture. Here we show a parallel architecture described by a sum of matrices. The theory is experimentally demonstrated by modulating spatially-separated polarization components of a laser using a digital micromirror device that are subsequently beam combined. This method greatly expands the parameter space for engineering devices that control polarization. Consequently, performance characteristics, such as speed, stability, and spectral range, are entirely dictated by the technologies of optical intensity modulation, including absorption, reflection, emission, and scattering. This opens up important prospects for polarization state generation (PSG) with unique performance characteristi...

  3. Introduction to fluorescence

    CERN Document Server

    Jameson, David M

    2014-01-01

    "An essential contribution to educating scientists in the principles of fluorescence. It will also be an important addition to the libraries of practitioners applying the principles of molecular fluorescence."-Ken Jacobson, Kenan Distinguished Professor of Cell Biology and Physiology, University of North Carolina at Chapel Hill"An exquisite compendium of fluorescence and its applications in biochemistry enriched by a very exciting historical perspective. This book will become a standard text for graduate students and other scientists."-Drs. Zygmunt (Karol) Gryczynski and Ignacy Gryczynski, University of North Texas Health Science Center"… truly a masterwork, combining clarity, precision, and good humor. The reader, novice or expert, will be pleased with the text and will not stop reading. It is a formidable account of the fluorescence field, which has impacted the life sciences so considerably in the last 60 years."-Jerson L. Silva, M.D., Ph.D., Professor and Director, National Institute of Science and Tech...

  4. Functional Fluorescent Organic Nanoparticles

    OpenAIRE

    Campioli, Elisa

    2013-01-01

    This thesis presents an extensive study on fluorescent organic nanoparticles and fluorescent organic binary and ternary nanoassemblies. In particular the attention is focused on the preparation and characterization of organic nanoparticles and new nanocomposites obtained from different types of small organic molecules, their stabilization and the use of these materials for biological and optoelectronics applications. The work deals at the beginning with the description of some methods used...

  5. Cutin fluorescence in early embryos of Pinus and Tsuga

    Directory of Open Access Journals (Sweden)

    Ewa Szczuka

    2014-01-01

    Full Text Available Embryos of Pinus nigra Arnold and Tsuga canadensis Carr. (Pinaceae at different stages of development were dissected from fresh, unfixed seeds and examined in a fluorescence microscope with 400 nm excitation light. The embryos of the investigated species showed cutin fluorescence after auramine 0 staining. At first the fluorescing cutin layer was formed on the apical part of the embryo with a well developed secondary suspensor, then it extended over the lateral surface of the embryo; the suspensor remained nonfluorescent. The fluorescing cutin layer occurred on the apical and side surface of the embryo, undergoing differentiation into the shoot axis and root initials. It is assumed that polarization and nutrition of the embryo may be influenced by presence of the cuticle.

  6. Monitoring membrane hydration with 2-(dimethylamino)-6-acylnaphtalenes fluorescent probes

    DEFF Research Database (Denmark)

    Bagatolli, Luis

    2015-01-01

    , were used to study membrane lateral structure and associated dynamics. Once incorporated into membranes, the (nanosecond) fluorescent decay of these probes is strongly affected by changes in the local polarity and relaxation dynamics of restricted water molecules existing at the membrane....../water interface. For instance, when glycerophospholipid containing membranes undertake a solid ordered (gel) to liquid disordered phase transition the fluorescence emission maximum of these probes shift ~ 50 nm with a significant change in their fluorescence lifetime. Furthermore, the fluorescence parameters...... of LAURDAN and PRODAN are exquisitely sensitive to cholesterol effects, allowing interpretations that correlate changes in membrane packing with membrane hydration. Different membrane model systems as well as innate biological membranes have been studied with this family of probes allowing interesting...

  7. Polarization Ratio Determination with Two Identical Linearly Polarized Antennas

    Science.gov (United States)

    2017-01-17

    Polarization Ratio Determination with Two Identical Linearly Polarized Antennas Herbert M. Aumann1, Francis G. Willwerth2 and Kristan A. Tuttle2...maine.edu Abstract— This paper describes a method for determining the complex polarization ratio using two identical, linearly polarized antennas. By...present paper it will be shown that the later technique can also be used to determine the polarization ratio of a linearly polarized antenna. II

  8. Influence of polarization extinction ratio on distributed polarization coupling detection

    Institute of Scientific and Technical Information of China (English)

    XU Tian-hua; TANG Feng; JING Wen-cai; ZHANG Hong-xia; JIA Da-gong; YU Chang-song; ZHOU Ge; ZHANG Yi-mo

    2008-01-01

    Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelsonin terferorneter. This technique usually requires that only one polarization mode is excited. However, in practical measurement,the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of theincident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.

  9. Optical characterization and polarization calibration for rigid endoscopes

    Science.gov (United States)

    Garcia, Missael; Gruev, Viktor

    2017-02-01

    Polarization measurements give orthogonal information to spectral images making them a great tool in the characterization of environmental parameters in nature. Thus, polarization imagery has proven to be remarkably useful in a vast range of biomedical applications. One such application is the early diagnosis of flat cancerous lesions in murine colorectal tumor models, where polarization data complements NIR fluorescence analysis. Advances in nanotechnology have led to compact and precise bio-inspired imaging sensors capable of accurately co-registering multidimensional spectral and polarization information. As more applications emerge for these imagers, the optics used in these instruments get very complex and can potentially compromise the original polarization state of the incident light. Here we present a complete optical and polarization characterization of three rigid endoscopes of size 1.9mm x 10cm (Karl Storz, Germany), 5mm x 30cm, and 10mm x 33cm (Olympus, Germany), used in colonoscopy for the prevention of colitis-associated cancer. Characterization results show that the telescope optics act as retarders and effectively depolarize the linear component. These incorrect readings can cause false-positives or false-negatives leading to an improper diagnosis. In this paper, we offer a polarization calibration scheme for these endoscopes based on Mueller calculus. By modeling the optical properties from training data as real-valued Mueller matrices, we are able to successfully reconstruct the initial polarization state acquired by the imaging system.

  10. Correlation comparative analysis on the high performance liquid chromatography and fluorescence polarization immunoassay in the determination of serum concentrations of antiepileptic drugs%高效液相色谱法与荧光偏振免疫法在抗癫痫药血清浓度测定中的相关性比较分析

    Institute of Scientific and Technical Information of China (English)

    章佳佳

    2013-01-01

    Objective To explore the correlation of two methods of high performance liquid chromatography (HPLC) and fluorescence polarization immunoassay (FPIA) in the determination of serum concentrations of antiepileptic drugs. Methods The serum of 103 patients with epilepsy treated by phenytoin(PT), phenobarbital(PB) and carbamazepine(CBZ) in our hospital were collected, and the serum concentrations were determined by respectively using HPLC and FPIA and dong linear regression analysis. Results The linear regression equation was YPT=-1.421+1.141X (r=0.963), YPB= -0.128+0.956X (r=0.949), YCBZ=0.183+0.954X (r=0.944), and the value obtained by the two methods showed the linear correlation; The paired t-test showed that the difference was not statistically significant between the both (P > 0.05). Conclusion The serum concentrations of antiepileptic drugs determined by the two methods of HPLC and FPIA is relevant. The determination of serum concentrations of CBZ, PT, PB by using HPLC and FPIA have their pros and cons, the monitoring methods are reasonably chosen by combining with the number of drugs and subjects.%目的:探究HPLC与FPIA两种方法在抗癫痫药血清浓度测定中的相关性。方法采集本院收治的经苯妥英钠(PT)、苯巴比妥(PB)、卡马西平(CBZ)治疗的103例癫痫患者血清,分别采用高效液相色谱法、荧光偏振免疫法测定其血药浓度并进行线性回归分析。结果所得的线性回归方程为YPT=-1.421+1.141X(r=0.963);YPB=-0.128+0.956X(r=0.949);YCBZ=0.183+0.954X(r=0.944),且两种方法测得的值呈线性相关;经配对t检验后,两者差异有统计学意义(P>0.05)。结论高效液相色谱法与荧光偏振免疫法两种方法测定抗癫痫药血清浓度具有相关性。采用HPLC法和FPIA法进行CBZ、PT、PB的血清浓度测定各有利弊,须结合检测药物种类数目、受检人数等合理选择监测方式。

  11. 高效液相色谱法、荧光偏振免疫分析法和质谱法监测丙戊酸血药浓度的比较%Comparison of high performance liquid chromatography, fluorescence polarization immunoassay and mass spectrometer method in determination of valproic acid in serum

    Institute of Scientific and Technical Information of China (English)

    赵明明; 孙亚欣; 邱枫; 徐英宏; 肇丽梅

    2015-01-01

    Objective To compare high performance liquid chromatog-raphy ( HPLC ) , fluorescence polarization immunoassay ( FPIA ) and mass spectrometer ( HPLC-MS) method for the determination of valproic acid in serum and to evaluate the correlations among three methods.Methods Two hundred and seven steady -state serum samples were collected from epileptic patients who had taken valproate.Three methods were employed to determine the concentration of valproic acid ( VPA ) and the results were analyzed to evaluate the correlation and difference.Results The results determined by three methods had high correlation.However, there was significant difference between HPLC and FPIA method.The concentration determined by FPIA was 0.7 μg · mL-1 higher than that of HPLC (95%CI:-8.6~9.9 μg· mL-1 ).When the concentration of valproic acid was less than 90μg· mL-1 , the two meth-ods appeared no significant difference.While the concentration of valpro-ic acid was more than 90μg· mL-1 , there was significant difference be-tween the two methods.Conclusion It is necessary to pay attention to the difference among three methods when monitoring the concentration of valproic acid in clinical practice.When the concentration was more than 90 μg· mL-1 , the results determined by HPLC and FPIA method could not be compared directly.%目的:比较高效液相色谱法(HPLC)、荧光偏振免疫分析法(FPIA)和质谱法( HPLC-MS)监测丙戊酸血药浓度的相关性。方法收集规律服用丙戊酸制剂达稳态后的血清样本207例,分别用3种方法进行测定,考察3种测定方法的相关性和差异性。结果3种测定方法的相关性良好,但总体水平上HPLC法与FPIA法测定结果相比较差异有统计学意义。 FPIA法测定丙戊酸血药浓度较HPLC法高0.7μg· mL-1(95%CI:-8.6~9.9μg· mL-1),当血药浓度数据处于低、中浓度(<90μg· mL-1)时,2种方法所测定结果均值相近,且差异无统

  12. Determination of Composition in PM10 Aerosols by High-Energy Polarized Energy-Dispersive X-ray Fluorescence Spectrometry%高能偏振能量色散-X射线荧光光谱法测定PM10大气颗粒物的组成

    Institute of Scientific and Technical Information of China (English)

    吉昂; 郑南; 王河锦; 徐子优; 李国会

    2011-01-01

    In order to coordinate with X-ray Diffractomer (XRD) research on analyzing the crystal phase of inhaled aerosol PM10 qualitatively and quantitatively, a method of using High-Energy Polarized Energy-Dispersive X-ray Fluorescence Spectrometry (HE-P-EDXRF) was developed to quantitatively measure the major and minor elements in aerosol PM10 collected on Whatman glass fiber filters. The study focused on the effect of the blank values of air filter membrane for the measurement compositions of aerosol PM10. The results indicate that the standards with glass fiber membrane filter should be used as carriers if the elemental area density of the blank glass fiber filter is more than 0. 1 μg/cm3, and the nuclepore polycarbonate aerosol membrane filter should be used if the elemental area density is less than 0. 1 μg/cm3. The measurement of heavy trace elements using He-P-EDXRF was also investigated, and extended the scope of the measuring elements to 62. The detection limits of Na, Mg, S, Y, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu were more than 0. 1 μg/m2, the detection limits of Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br and Rb were less than 0.01 μg/m2, and the detection limits of Cl, Al, Si, P, K, Sc, Ti, V, Ge, As, Br, Se, Sr, Zr, Mo, Pd, Rh, In, Nb, Ag, Cd, Te, Sb, Sn, Ba, Cs, La, Ce, Pr, Au, Pt, W, Tl, Pb, Bi, Th and U were 0. 1 -0.01 μg/cm2.%为配合X射线衍射分析(XRD)方法对可吸入大气颗粒悬浮物(PM10)的结晶物相进行定性和定量分析的研究工作,本文应用高能偏振能量色散X射线荧光光谱(HE- P-EDXRF)对Whatman玻璃纤维滤膜采集的PM10颗粒物中主、次量元素进行定量分析,着重研究了空气滤膜空白值对测定PM10颗粒物中组成的影响.结果表明,当玻璃纤维滤膜空白值中元素的面密度大于0.1μg/cm2时,需使用玻璃纤维滤膜为载体的标准样品;元素的面密度小于0.1μg/cm2时,可用聚碳酸脂膜为载体的标准样品.对HE-P-EDXRF谱仪测定PM10颗粒物中

  13. 地质样品铷锶钇锆元素偏振能量色散X射线荧光光谱分析结果不确定度的评估%The Evaluation of Uncertainty in the Results for Elements Rubidium, Strontium, Yttrium and Zirconium in Silicate Geological Samples by Polarized Energy Dispersive X-Ray Fluorescence Spectrometry

    Institute of Scientific and Technical Information of China (English)

    王祎亚; 詹秀春; 袁继海; 樊兴涛

    2011-01-01

    建立了一种以相对误差的标准偏差统计不确定度的评估方法.运用镶边压片技术制备样片,用Spectm X-Lab 2000型偏振能量色散X射线荧光光谱(P-EDXRF)仪器分析硅酸盐基体的76个国家一级标准物质和89个地质行业多目标考核样品,研究表明165个样品Rb,Sr,Y和Zr元素测量结果的相对误差符合正态分布(置信度为95%).以此为依据,分段统计相对误差的标准偏差作为对应浓度段被测量结果的总相对不确定度,扩展因子为2.分段统计精密度引起的相对不确定度,剥离出准确度引起的相对不确定度.不同元素准确度引起的相对不确定度在总不确定度中所占比例不同.通过"实验室测量审核结果公式"和"标准值及其扩展不确定度与测试修正值及其扩展不确定度的比较"丽种方式,验证了总相对不确定度统计方式具有合理性.%A method for evaluation of uncertainty was established with standard deviation of relative error. Utilizing a polarized energy dispersive x ray fluorescence spectrometer(P-EDXRF)X-lab 2000 with pressed polyethylene-backed pellets, 76 national reference materials and 89 geological examination samples were analyzed, the results indicated that the relative errors consist with the normal distribution with confidence level 95%. The section standard deviations of relative errors acted as method global relative uncertainty and expanded factor was 2. The section relative uncertainty caused by precision was analyzed and relative uncertainty caused by accuracy based on the error transfer formula was isolated. The ratio of relative uncertainty caused by accuracy to the global relative uncertainty was different with different levels and elements. Two methods validated that the evaluation of global uncertainty is reasonable, with the first method being the formula of audited results in laboratory, and the second being the comparison of standard value with expanded uncertainty and a

  14. Polarization measurement in the COMPASS polarized target

    CERN Document Server

    Kondo, K; Baum, G; Berglund, P; Doshita, N; Gautheron, F; Görtz, S; Hasegawa, T; Horikawa, N; Ishimoto, S; Iwata, T; Kisselev, Yu V; Koivuniemi, J H; Le Goff, J M; Magnon, A; Meyer, W; Reicherz, G; Matsuda, T

    2004-01-01

    Continuous wave nuclear magnetic resonance (NMR) is used to determine the target polarization in the COMPASS experiment. The system is made of the so-called Liverpool Q-meters, Yale-cards, and VME modules for data taking and system controlling. In 2001 the NMR coils were embedded in the target material, while in 2002 and 2003 the coils were mounted on the outer surface of the target cells to increase the packing factor of the material. Though the error of the measurement became larger with the outer coils than with the inner coils, we have performed stable measurements throughout the COMPASS run time for 3 years. The maximum polarization was +57% and -53% as the average in the target cells.

  15. The Use of Coumarins as Environmentally-Sensitive Fluorescent Probes of Heterogeneous Inclusion Systems

    Directory of Open Access Journals (Sweden)

    Brian D. Wagner

    2009-01-01

    Full Text Available Coumarins, as a family of molecules, exhibit a wide range of fluorescence emission properties. In many cases, this fluorescence is extremely sensitive to the local environment of the molecule, especially the local polarity and microviscosity. In addition, coumarins show a wide range of size, shape, and hydrophobicity. These properties make them especially useful as fluorescent probes of heterogeneous environments, such as supramolecular host cavities, micelles, polymers and solids. This article will review the use of coumarins to probe such heterogeneous systems using fluorescence spectroscopy.

  16. Time Domain Induced Polarization

    DEFF Research Database (Denmark)

    Fiandaca, Gianluca; Auken, Esben; Christiansen, Anders Vest

    2012-01-01

    Time-domain-induced polarization has significantly broadened its field of reference during the last decade, from mineral exploration to environmental geophysics, e.g., for clay and peat identification and landfill characterization. Though, insufficient modeling tools have hitherto limited the use...... of time-domaininduced polarization for wider purposes. For these reasons, a new forward code and inversion algorithm have been developed using the full-time decay of the induced polarization response, together with an accurate description of the transmitter waveform and of the receiver transfer function......%. Furthermore, the presence of low-pass filters in time-domain-induced polarization instruments affects the early times of the acquired decays (typically up to 100 ms) and has to be modeled in the forward response to avoid significant loss of resolution. The developed forward code has been implemented in a 1D...

  17. Dynamic nuclear spin polarization

    Energy Technology Data Exchange (ETDEWEB)

    Stuhrmann, H.B. [GKSS-Forschungszentrum Geesthacht GmbH (Germany)

    1996-11-01

    Polarized neutron scattering from dynamic polarized targets has been applied to various hydrogenous materials at different laboratories. In situ structures of macromolecular components have been determined by nuclear spin contrast variation with an unprecedented precision. The experiments of selective nuclear spin depolarisation not only opened a new dimension to structural studies but also revealed phenomena related to propagation of nuclear spin polarization and the interplay of nuclear polarisation with the electronic spin system. The observation of electron spin label dependent nuclear spin polarisation domains by NMR and polarized neutron scattering opens a way to generalize the method of nuclear spin contrast variation and most importantly it avoids precontrasting by specific deuteration. It also likely might tell us more about the mechanism of dynamic nuclear spin polarisation. (author) 4 figs., refs.

  18. Invariants of polarization transformations.

    Science.gov (United States)

    Sadjadi, Firooz A

    2007-05-20

    The use of polarization-sensitive sensors is being explored in a variety of applications. Polarization diversity has been shown to improve the performance of the automatic target detection and recognition in a significant way. However, it also brings out the problems associated with processing and storing more data and the problem of polarization distortion during transmission. We present a technique for extracting attributes that are invariant under polarization transformations. The polarimetric signatures are represented in terms of the components of the Stokes vectors. Invariant algebra is then used to extract a set of signature-related attributes that are invariant under linear transformation of the Stokes vectors. Experimental results using polarimetric infrared signatures of a number of manmade and natural objects undergoing systematic linear transformations support the invariancy of these attributes.

  19. POLARIZED LIGHT IN PHYSIOTHERAPY

    National Research Council Canada - National Science Library

    L. D. Tondiy; O. L. Tondiy; I. V. Kas; O. V. Zemlyana; O. L. Zakrevska; V. O. Zhuravliev

    2015-01-01

    The data on polarized light (PS) - a new promising treatment, rehabilitation and prevention, which took its deserved place among the known therapeutic physical factors and may even compete with laser radiation of low and LED therapy...

  20. Cell Polarity in Yeast.

    Science.gov (United States)

    Chiou, Jian-Geng; Balasubramanian, Mohan K; Lew, Daniel J

    2017-08-07

    A conserved molecular machinery centered on the Cdc42 GTPase regulates cell polarity in diverse organisms. Here we review findings from budding and fission yeasts that reveal both a conserved core polarity circuit and several adaptations that each organism exploits to fulfill the needs of its lifestyle. The core circuit involves positive feedback by local activation of Cdc42 to generate a cluster of concentrated GTP-Cdc42 at the membrane. Speciesspecific pathways regulate the timing of polarization during the cell cycle, as well as the location and number of polarity sites. Expected final online publication date for the Annual Review of Cell and Developmental Biology Volume 33 is October 6, 2017. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

  1. Coordenadas polares: curvas maravillosas

    OpenAIRE

    Norberto Jaime Chau Pérez; Roy Wil Sánchez Gutiérrez

    2010-01-01

    Se presenta una actividad colaborativa en la que se trabaja el tema coordenadas polares. Se presentan los objetivos de aprendizaje, el desarrollo de la actividad, los conocimientos previos necesarios y recomendaciones para una aplicación posterior.

  2. Political Competition and Polarization

    DEFF Research Database (Denmark)

    Schultz, Christian

    This paper considers political competition and the consequences of political polarization when parties are better informed about how the economy functions than voters are. Specifically, parties know the cost producing a public good, voters do not. An incumbent's choice of policy acts like a signal...... for costs before an upcoming election. It is shown that the more polarized the political parties the more distorted the incumbent's policy choice....

  3. Polar Warming Drivers

    Science.gov (United States)

    McDunn, T. L.; Bougher, S. W.; Mischna, M. A.; Murphy, J. R.

    2012-12-01

    Polar warming is a dynamically induced temperature enhancement over mid-to-high latitudes that results in a reversed (poleward) meridional temperature gradient. This phenomenon was recently characterized over the 40-90 km altitude region [1] based on nearly three martian years of Mars Climate Sounder observations [2, 3]. Here we investigate which forcing mechanisms affect the magnitude and distribution of the observed polar warming by conducting simulations with the Mars Weather Research and Forecasting General Circulation Model [4, 5]. We present simulations confirming the influence topography [6] and dust loading [e.g., 7] have upon polar warming. We then present simulations illustrating the modulating influence gravity wave momentum deposition exerts upon polar warming, consistent with previous modeling studies [e.g., 8]. The results of this investigation suggest the magnitude and distribution of polar warming in the martian middle atmosphere is modified by gravity wave activity and that the characteristics of the gravity waves that most significantly affect polar warming vary with season. References: [1] McDunn, et al., 2012 (JGR), [2]Kleinböhl, et al., 2009 (JGR), [3] Kleinböhl, et al., 2011 (JQSRT), [4] Richardson, et al., 2007 (JGR), [5] Mischna, et al., 2011 (Planet. Space Sci.), [6] Richardson and Wilson, 2002 (Nature), [7] Haberle, et al., 1982 (Icarus), [8] Barnes, 1990 (JGR).

  4. Fluorescence properties of crown ethers with phenylbenzothiozole pendant group

    Science.gov (United States)

    Kapoor, S.; Sapre, A. V.; Kumar, S.; Mashraqui, S. H.; Mukherjee, T.

    2005-06-01

    Photophysical characteristics of 2-phenylbenzothiazole (PBT) substituted crown ether (CRE-PBT) molecules have been investigated in various polar protic solvents. Large Stokes' and good solvatochromic shifts have been observed for CRE-PBT molecules. It is seen that in these molecules, the fluorescence lifetimes and quantum yields increase as compared to the pristine PBT molecule. Temperature-dependence studies have been carried out to understand the effect of CRE substitution and the role of C-C single bond rotation on the fluorescence quantum yield and lifetime.

  5. Stroboscopic fluorescence lifetime imaging.

    Science.gov (United States)

    Holton, Mark D; Silvestre, Oscar R; Errington, Rachel J; Smith, Paul J; Matthews, Daniel R; Rees, Paul; Summers, Huw D

    2009-03-30

    We report a fluorescence lifetime imaging technique that uses the time integrated response to a periodic optical excitation, eliminating the need for time resolution in detection. A Dirac pulse train of variable period is used to probe the frequency response of the total fluorescence per pulse leading to a frequency roll-off that is dependent on the relaxation rate of the fluorophores. The technique is validated by demonstrating wide-field, realtime, lifetime imaging of the endocytosis of inorganic quantum dots by a cancer cell line. Surface charging of the dots in the intra-cellular environment produces a switch in the fluorescence lifetime from approximately 40 ns to technique offers lifetime based imaging at video rates with standard CCD cameras and has application in probing millisecond cell dynamics and in high throughput imaging assays.

  6. A fluorescence study on the interaction of telmisartan in triblock polymers pluronic P123 and F127

    Science.gov (United States)

    Mohanty, Maneesha Esther; Rao, Vaidya Jayathirtha; Mishra, Ashok Kumar

    2014-03-01

    Telmisartan is a poorly soluble drug used in treatment of hypertension. There is a recent interest to use pluronic for improving the solubility and bioavailability of these drugs. In this study the interaction of telmisartan with P123 and F127 has been carried out using steady state and time dependent fluorescence study. Quenching of telmisartan fluorescence by potassium iodide is controlled by interactions arising from collisions and complex formation. A comparison of the fluorescence of telmisartan in pluronics with the well understood fluorescence of 8-anilino-1-naphthalene-sulfonic acid, a known fluorescent molecular probe, indicates that telmisartan is generally present in a relatively polar microenvironment with restricted diffusive motion.

  7. Polarization properties of linearly polarized parabolic scaling Bessel beams

    Science.gov (United States)

    Guo, Mengwen; Zhao, Daomu

    2016-10-01

    The intensity profiles for the dominant polarization, cross polarization, and longitudinal components of modified parabolic scaling Bessel beams with linear polarization are investigated theoretically. The transverse intensity distributions of the three electric components are intimately connected to the topological charge. In particular, the intensity patterns of the cross polarization and longitudinal components near the apodization plane reflect the sign of the topological charge.

  8. Nanosecond fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Leskovar, B.

    1985-03-01

    This article is a summary of a short course lecture given in conjunction with the 1984 Nuclear Science Symposium. Measuring systems for nanosecond fluorescence spectroscopy using single-photon counting techniques are presented. These involve systems based on relaxation-type spark gap light pulser and synchronously pumped mode-locked dye lasers. Furthermore, typical characteristics and optimization of operating conditions of the critical components responsible for the system time resolution are discussed. A short comparison of the most important deconvolution methods for numerical analysis of experimental data is given particularly with respect to the signal-to-noise ratio of the fluorescence signal. 22 refs., 8 figs.

  9. Polarized Light Microscopy

    Science.gov (United States)

    Frandsen, Athela F.

    2016-01-01

    Polarized light microscopy (PLM) is a technique which employs the use of polarizing filters to obtain substantial optical property information about the material which is being observed. This information can be combined with other microscopy techniques to confirm or elucidate the identity of an unknown material, determine whether a particular contaminant is present (as with asbestos analysis), or to provide important information that can be used to refine a manufacturing or chemical process. PLM was the major microscopy technique in use for identification of materials for nearly a century since its introduction in 1834 by William Fox Talbot, as other techniques such as SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared spectroscopy), XPD (X-ray Powder Diffraction), and TEM (Transmission Electron Microscopy) had not yet been developed. Today, it is still the only technique approved by the Environmental Protection Agency (EPA) for asbestos analysis, and is often the technique first applied for identification of unknown materials. PLM uses different configurations in order to determine different material properties. With each configuration additional clues can be gathered, leading to a conclusion of material identity. With no polarizing filter, the microscope can be used just as a stereo optical microscope, and view qualities such as morphology, size, and number of phases. With a single polarizing filter (single polars), additional properties can be established, such as pleochroism, individual refractive indices, and dispersion staining. With two polarizing filters (crossed polars), even more can be deduced: isotropy vs. anisotropy, extinction angle, birefringence/degree of birefringence, sign of elongation, and anomalous polarization colors, among others. With the use of PLM many of these properties can be determined in a matter of seconds, even for those who are not highly trained. McCrone, a leader in the field of polarized light microscopy, often

  10. Ultrafast excited state dynamics of the green fluorescent protein chromophore and its kindling fluorescent protein analogue.

    Science.gov (United States)

    Addison, Kiri; Heisler, Ismael A; Conyard, Jamie; Dixon, Tara; Page, Philip C Bulman; Meech, Stephen R

    2013-01-01

    Fluorescent proteins exhibit a very diverse range of photochemical behaviour, from efficient fluorescence through photochromism to photochemical reactivity. Remarkably this diverse behaviour arises from chromophores which have very similar structures. Here we describe measurements and modelling of the excited state dynamics in the chromophores of GFP (HBDI) and the kindling fluorescent protein, KFP (FHBMI). The methods are ultrafast fluorescence spectroscopy with sub 50 fs time resolution and the modelling is based on the Smoluchowski equation. The excited state decays of both chromophores are very fast, longer for their anions than for the neutral form and independent of wavelength. Detailed studies show the mean fluorescence wavelength to be independent of time. The excited state decay times are also observed to be a very weak function of solvent polarity and viscosity. These results are modelled utilising recently calculated potential energy surfaces for the ground and excited states as a function of the twist coordinates about the two bridging bonds of the chromophore. For FHBMI and the scarce data on the neutral HBDI the calculations are not successful suggesting the need for refinement of these potential energy surfaces. For HBDI in methanol the simulation is successful provided a strong dependence of the radiationless decay rate on the coordinate is assumed. Such dependence should be included in future calculations of excited state dynamics. When the simulations are extended to more viscous solvents they fail to reproduce the observed weak viscosity dependence. The implications of these results for the nature of the coordinate leading to radiationless decay in the chromophore and for the photodynamics of fluorescent proteins are discussed.

  11. MultiFocus Polarization Microscope (MF-PolScope) for 3D polarization imaging of up to 25 focal planes simultaneously.

    Science.gov (United States)

    Abrahamsson, Sara; McQuilken, Molly; Mehta, Shalin B; Verma, Amitabh; Larsch, Johannes; Ilic, Rob; Heintzmann, Rainer; Bargmann, Cornelia I; Gladfelter, Amy S; Oldenbourg, Rudolf

    2015-03-23

    We have developed an imaging system for 3D time-lapse polarization microscopy of living biological samples. Polarization imaging reveals the position, alignment and orientation of submicroscopic features in label-free as well as fluorescently labeled specimens. Optical anisotropies are calculated from a series of images where the sample is illuminated by light of different polarization states. Due to the number of images necessary to collect both multiple polarization states and multiple focal planes, 3D polarization imaging is most often prohibitively slow. Our MF-PolScope system employs multifocus optics to form an instantaneous 3D image of up to 25 simultaneous focal-planes. We describe this optical system and show examples of 3D multi-focus polarization imaging of biological samples, including a protein assembly study in budding yeast cells.

  12. [Polar and non polar notations of refraction].

    Science.gov (United States)

    Touzeau, O; Gaujoux, T; Costantini, E; Borderie, V; Laroche, L

    2010-01-01

    Refraction can be expressed by four polar notations which correspond to four different combinations of spherical or cylindrical lenses. Conventional expressions of refraction (plus and minus cylinder notation) are described by sphere, cylinder, and axis. In the plus cylinder notation, the axis visualizes the most powerful meridian. The axis usually corresponds to the bow tie axis in curvature maps. Plus cylinder notation is also valuable for all relaxing procedures (i.e., selective suture ablation, arcuate keratotomy, etc.). In the cross-cylinder notation, two orthogonal cylinders can describe (without the sphere component) the actual refraction of both the principal meridians. This notation must be made before performing the vertex calculation. Using an association of a Jackson cross-cylinder and a spherical equivalent, refraction can be broken down into two pure components: astigmatism and sphere. All polar notations of refraction may perfectly characterize a single refraction but are not suitable for statistical analysis, which requires nonpolar expression. After doubling the axis, a rectangular projection breaks down the Jackson cross-cylinder, which has a polar axis, into two Jackson cross-cylinders on the 0 degrees /90 degrees and 45 degrees /135 degrees axis. This procedure results in the loss of the directional nature of the data. Refraction can be written in a nonpolar notation by three rectangular coordinates (x,y,z), which can also represent the spherocylinder by one point in a dioptric space. These three independent (orthogonal) variables have a concrete optical significance: a spherical component, a direct/inverse (WTR/ATR) component, and an oblique component of the astigmatism. Finally, nonpolar notations are useful for statistical analysis and graphical representation of refraction.

  13. When measured spin polarization is not spin polarization

    Science.gov (United States)

    Dowben, P. A.; Wu, Ning; Binek, Christian

    2011-05-01

    Spin polarization is an unusually ambiguous scientific idiom and, as such, is rarely well defined. A given experimental methodology may allow one to quantify a spin polarization but only in its particular context. As one might expect, these ambiguities sometimes give rise to inappropriate interpretations when comparing the spin polarizations determined through different methods. The spin polarization of CrO2 and Cr2O3 illustrate some of the complications which hinders comparisons of spin polarization values.

  14. Polarized nuclear target based on parahydrogen induced polarization

    Energy Technology Data Exchange (ETDEWEB)

    D. Budker, M.P. Ledbetter, S. Appelt, L.S. Bouchard, B. Wojtsekhowski

    2012-12-01

    We discuss a novel concept of a polarized nuclear target for accelerator fixed-target scattering experiments, which is based on parahydrogen induced polarization (PHIP). One may be able to reach a 33% free-proton polarization in the ethane molecule. The potential advantages of such a target include operation at zero magnetic field, fast ({approx}100 HZ) polarization oscillation (akin to polarization reversal), and operation with large intensity of an electron beam.

  15. d-PET-controlled “off-on” Polarity-sensitive Probes for Reporting Local Hydrophilicity within Lysosomes

    Science.gov (United States)

    Zhu, Hao; Fan, Jiangli; Mu, Huiying; Zhu, Tao; Zhang, Zhen; Du, Jianjun; Peng, Xiaojun

    2016-10-01

    Polarity-sensitive fluorescent probes are powerful chemical tools for studying biomolecular structures and activities both in vitro and in vivo. However, the lack of “off-on” polarity-sensing probes has limited the accurate monitoring of biological processes that involve an increase in local hydrophilicity. Here, we design and synthesize a series of “off-on” polarity-sensitive fluorescent probes BP series consisting of the difluoroboron dippyomethene (BODIPY) fluorophore connected to a quaternary ammonium moiety via different carbon linkers. All these probes showed low fluorescence quantum yields in nonpolar solution but became highly fluorescent in polar media. BP-2, which contains a two-carbon linker and a trimethyl quaternary ammonium, displayed a fluorescence intensity and quantum yield that were both linearly correlated with solvent polarity. In addition, BP-2 exhibited high sensitivity and selectivity for polarity over other environmental factors and a variety of biologically relevant species. BP-2 can be synthesized readily via an unusual Mannich reaction followed by methylation. Using electrochemistry combined with theoretical calculations, we demonstrated that the “off-on” sensing behavior of BP-2 is primarily due to the polarity-dependent donor-excited photoinduced electron transfer (d-PET) effect. Live-cell imaging established that BP-2 enables the detection of local hydrophilicity within lysosomes under conditions of lysosomal dysfunction.

  16. Cylindrically Polarized Nondiffracting Optical Pulses

    CERN Document Server

    Ornigotti, Marco; Szameit, Alexander

    2016-01-01

    We extend the concept of radially and azimuthally polarized optical beams to the polychromatic domain by introducing cylindrically polarized nondiffracting optical pulses. In particular, we discuss in detail the case of cylindrically polarized X-waves, both in the paraxial and nonparaxial regime. The explicit expressions for the electric and magnetic fields of cylindrically polarized X-waves is also reported.

  17. Sequential Polarity-Reversing Circuit

    Science.gov (United States)

    Labaw, Clayton C.

    1994-01-01

    Proposed circuit reverses polarity of electric power supplied to bidirectional dc motor, reversible electro-mechanical actuator, or other device operating in direction depending on polarity. Circuit reverses polarity each time power turned on, without need for additional polarity-reversing or direction signals and circuitry to process them.

  18. Automated control of optical polarization for nonlinear microscopy

    Science.gov (United States)

    Brideau, Craig; Stys, Peter K.

    2012-03-01

    Laser-scanning non-linear optical techniques such as multi-photon fluorescence excitation microscopy (MPM), Second/ Third Harmonic Generation (SHG/THG), and Coherent Anti-Stokes Raman Scattering (CARS) are being utilized in research laboratories worldwide. The efficiencies of these non-linear effects are dependent on the polarization state of the excitation light relative to the orientation of the sample being imaged. In highly ordered anisotropic biological samples this effect can become pronounced and the excitation polarization can have a dramatic impact on imaging experiments. Therefore, controlling the polarization state of the exciting light is important; however this is challenging when the excitation light passes through a complex optical system. In a typical laser-scanning microscope, components such as the dichroic filters, lenses, and even mirrors can alter the polarization state of a laser beam before it reaches the sample. We present an opto-mechanical solution to compensate for the polarization effects of an optical path, and to precisely program the polarization state of the exciting laser light. The device and accompanying procedures allow the delivery of precise laser polarization states at constant average power levels to a sample during an imaging experiment.

  19. Efficient room-temperature source of polarized single photons

    Science.gov (United States)

    Lukishova, Svetlana G.; Boyd, Robert W.; Stroud, Carlos R.

    2007-08-07

    An efficient technique for producing deterministically polarized single photons uses liquid-crystal hosts of either monomeric or oligomeric/polymeric form to preferentially align the single emitters for maximum excitation efficiency. Deterministic molecular alignment also provides deterministically polarized output photons; using planar-aligned cholesteric liquid crystal hosts as 1-D photonic-band-gap microcavities tunable to the emitter fluorescence band to increase source efficiency, using liquid crystal technology to prevent emitter bleaching. Emitters comprise soluble dyes, inorganic nanocrystals or trivalent rare-earth chelates.

  20. Effect of advection on transient ion concentration-polarization phenomenon

    Science.gov (United States)

    Rosentsvit, Leon; Park, Sinwook; Yossifon, Gilad

    2017-08-01

    Here, we studied the effect of advection on the transient ion concentration-polarization phenomenon in microchannel-membrane systems. Specifically, the temporal evolution of the depletion layer in a system that supports net flow rates with varying Péclet values was examined. Experiments complemented with simplified analytical one-dimensional semi-infinite modeling and numerical simulations demonstrated either suppression or enhancement of the depletion layer propagation against or with the direction of the net flow, respectively. Of particular interest was the third-species fluorescent dye ion concentration-polarization dynamics which was further explained using two-dimensional numerical simulations that accounted for the device complex geometry.

  1. DBD dyes as fluorescence lifetime probes to study conformational changes in proteins.

    Science.gov (United States)

    Wawrzinek, Robert; Ziomkowska, Joanna; Heuveling, Johanna; Mertens, Monique; Herrmann, Andreas; Schneider, Erwin; Wessig, Pablo

    2013-12-16

    Previously, [1,3]dioxolo[4,5-f][1,3]benzodioxole (DBD)-based fluorophores used as highly sensitive fluorescence lifetime probes reporting on their microenvironmental polarity have been described. Now, a new generation of DBD dyes has been developed. Although they are still sensitive to polarity, in contrast to the former DBD dyes, they have extraordinary spectroscopic properties even in aqueous surroundings. They are characterized by long fluorescence lifetimes (10-20 ns), large Stokes shifts (≈100 nm), high photostabilities, and high quantum yields (>0.56). Here, the spectroscopic properties and synthesis of functionalized derivatives for labeling biological targets are described. Furthermore, thio-reactive maleimido derivatives of both DBD generations show strong intramolecular fluorescence quenching. This mechanism has been investigated and is found to undergo a photoelectron transfer (PET) process. After reaction with a thiol group, this fluorescence quenching is prevented, indicating successful bonding. Being sensitive to their environmental polarity, these compounds have been used as powerful fluorescence lifetime probes for the investigation of conformational changes in the maltose ATP-binding cassette transporter through fluorescence lifetime spectroscopy. The differing tendencies of the fluorescence lifetime change for both DBD dye generations promote their combination as a powerful toolkit for studying microenvironments in proteins.

  2. Polarization twist in perovskite ferrielectrics.

    Science.gov (United States)

    Kitanaka, Yuuki; Hirano, Kiyotaka; Ogino, Motohiro; Noguchi, Yuji; Miyayama, Masaru; Moriyoshi, Chikako; Kuroiwa, Yoshihiro

    2016-09-02

    Because the functions of polar materials are governed primarily by their polarization response to external stimuli, the majority of studies have focused on controlling polar lattice distortions. In some perovskite oxides, polar distortions coexist with nonpolar tilts and rotations of oxygen octahedra. The interplay between nonpolar and polar instabilities appears to play a crucial role, raising the question of how to design materials by exploiting their coupling. Here, we introduce the concept of 'polarization twist', which offers enhanced control over piezoelectric responses in polar materials. Our experimental and theoretical studies provide direct evidence that a ferrielectric perovskite exhibits a large piezoelectric response because of extended polar distortion, accompanied by nonpolar octahedral rotations, as if twisted polarization relaxes under electric fields. The concept underlying the polarization twist opens new possibilities for developing alternative materials in bulk and thin-film forms.

  3. Polarization twist in perovskite ferrielectrics

    Science.gov (United States)

    Kitanaka, Yuuki; Hirano, Kiyotaka; Ogino, Motohiro; Noguchi, Yuji; Miyayama, Masaru; Moriyoshi, Chikako; Kuroiwa, Yoshihiro

    2016-01-01

    Because the functions of polar materials are governed primarily by their polarization response to external stimuli, the majority of studies have focused on controlling polar lattice distortions. In some perovskite oxides, polar distortions coexist with nonpolar tilts and rotations of oxygen octahedra. The interplay between nonpolar and polar instabilities appears to play a crucial role, raising the question of how to design materials by exploiting their coupling. Here, we introduce the concept of ‘polarization twist’, which offers enhanced control over piezoelectric responses in polar materials. Our experimental and theoretical studies provide direct evidence that a ferrielectric perovskite exhibits a large piezoelectric response because of extended polar distortion, accompanied by nonpolar octahedral rotations, as if twisted polarization relaxes under electric fields. The concept underlying the polarization twist opens new possibilities for developing alternative materials in bulk and thin-film forms. PMID:27586824

  4. Polarization twist in perovskite ferrielectrics

    Science.gov (United States)

    Kitanaka, Yuuki; Hirano, Kiyotaka; Ogino, Motohiro; Noguchi, Yuji; Miyayama, Masaru; Moriyoshi, Chikako; Kuroiwa, Yoshihiro

    2016-09-01

    Because the functions of polar materials are governed primarily by their polarization response to external stimuli, the majority of studies have focused on controlling polar lattice distortions. In some perovskite oxides, polar distortions coexist with nonpolar tilts and rotations of oxygen octahedra. The interplay between nonpolar and polar instabilities appears to play a crucial role, raising the question of how to design materials by exploiting their coupling. Here, we introduce the concept of ‘polarization twist’, which offers enhanced control over piezoelectric responses in polar materials. Our experimental and theoretical studies provide direct evidence that a ferrielectric perovskite exhibits a large piezoelectric response because of extended polar distortion, accompanied by nonpolar octahedral rotations, as if twisted polarization relaxes under electric fields. The concept underlying the polarization twist opens new possibilities for developing alternative materials in bulk and thin-film forms.

  5. Fluorescence Experiments with Quinine

    Science.gov (United States)

    O'Reilly, James E.

    1975-01-01

    Describes a series of experiments which illustrate the analytical capabilities of fluorescence, and outlines two straightforward analyses involving real analyses. These experiments are suitable for an undergraduate instrumental analysis course and require approximately six to seven hours of laboratory time. (MLH)

  6. FLEX: fluorescence explorer

    NARCIS (Netherlands)

    Stoll, M.Ph.; Court, A.J.; Smorenburg, C.; Visser, H.; Crocco, L.; Heilimo, J.; Honig, A.

    1999-01-01

    FLEX is a scientifically driven space mission to provide demonstration/validation of the instrumentation and technique for measuring the natural fluorescence of vegetation in the Fraunhofer lines. The payload consists of high spectral resolution (0.1-0.3 nm) CCD imaging grating spectrometer with two

  7. Polar low monitoring

    Science.gov (United States)

    Bobylev, Leonid; Zabolotskikh, Elizaveta; Mitnik, Leonid

    2010-05-01

    Polar lows are intense mesoscale atmospheric low pressure weather systems, developing poleward of the main baroclinic zone and associated with high surface wind speeds. Small size and short lifetime, sparse in-situ observations in the regions of their development complicate polar low study. Our knowledge of polar lows and mesocyclones has come almost entirely during the period of satellite remote sensing since, by virtue of their small horizontal scale, it was rarely possible to analyse these lows on conventional weather charts using only the data from the synoptic observing network. However, the effects of intense polar lows have been felt by coastal communities and seafarers since the earliest times. These weather systems are thought to be responsible for the loss of many small vessels over the centuries, although the nature of the storms was not understood and their arrival could not be predicted. The actuality of the polar low research is stipulated by their high destructive power: they are a threat to such businesses as oil and gas exploration, fisheries and shipping. They could worsen because of global warming: a shrinking of sea ice around the North Pole, which thawed to its record minimum in the summer of 2007, is likely to give rise to more powerful storms that form only over open water and can cause hurricane-strength winds. Therefore, study of polar lows, their timely detection, tracking and forecasting represents a challenge for today meteorology. Satellite passive microwave data, starting from Special Sensor Microwave Imager (SSM/I) onboard Defense Meteorological Satellite Program (DMSP) satellite, remain invaluable source of regularly available remotely sensed data to study polar lows. The sounding in this spectral range has several advantages in comparison with observations in visible and infrared ranges and Synthetic Aperture Radar (SAR) data: independence on day time and clouds, regularity and high temporal resolution in Polar Regions. Satellite

  8. Polarization swings in blazars

    Science.gov (United States)

    Lyutikov, Maxim; Kravchenko, Evgeniya V.

    2017-06-01

    We present a model of blazar variability that can both reproduce smooth large polarization angle swings and at the same time allow for the seemingly random behaviour of synchrotron fluxes, polarization fraction and, occasionally, π/2 polarization jumps. We associate the blazar flaring activity with a jet carrying helical magnetic fields and propagating along a variable direction (and possibly with a changing bulk Lorentz factor). The model predicts that for various jet trajectories (i) electric vector position angle (EVPA) can experience large smooth temporal variations, while at the same time polarization fraction (Π) can be highly variable; (ii) Π ∼ 0 near sudden EVPA jumps of 90°, but can also remain constant for large, smoother EVPA swings; (iii) the total angle of EVPA rotation can be arbitrarily large; and (iv) intensity I is usually maximal at points of fastest EVPA changes, but can have a minimum. Thus, even for a regular, deterministic motion of a steadily emitting jet, the observed properties can vary in a non-monotonic and/or seemingly stochastic way. Intrinsic fluctuations of the emissivity will further complicate the intensity profiles, but are expected to preserve the polarization structure.

  9. Laurdan fluorescence senses mechanical strain in the lipid bilayer membrane.

    Science.gov (United States)

    Zhang, Yan-Liang; Frangos, John A; Chachisvilis, Mirianas

    2006-09-01

    The precise molecular mechanisms by which cells transduce a mechanical stimulus into an intracellular biochemical response have not yet been established. Here, we show for the first time that the fluorescence emission of an environment-sensitive membrane probe Laurdan is modulated by mechanical strain of the lipid bilayer membrane. We have measured fluorescence emission of Laurdan in phospholipid vesicles of 30, 50, and 100 nm diameter to show that osmotically induced membrane tension leads to an increase in polarity (hydration depth) of the phospholipid bilayer interior. Our data indicate that the general polarization of Laurdan emission is linearly dependent on membrane tension. We also show that higher membrane curvature leads to higher hydration levels. We anticipate that the proposed method will facilitate future studies of mechanically induced changes in physical properties of lipid bilayer environment both in vitro and in vivo.

  10. Fluorescence dynamics of interactions between polyamide PyPyPyβDp and DNA

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Huijuan; WANG; Jin; WU; Yishi; YUAN; Gu; AI; Xicheng; WANG; Li

    2006-01-01

    The photophysical properties of the polyamide PyPyPyβDp (PPP) were investigated by means of steady-state absorption and fluorescence spectroscopies, as well as time-resolved fluorescence spectroscopy. It was found that the excited-state properties of PPP are very sensitive to solvents. In TKMC buffer PPP exhibited weak fluorescence with a decay time constant of 16 ps, while with the decrease of the solvent polarity PPP showed the blue-shifted peak position, increased intensity and lengthened life-time for its fluorescence behavior. In the presence of calf thymus DNA, it was observed that the fluorescence intensity was enhanced and the fluorescence lifetime increased from 16 to 32 ps for PPP, which verified that PPP bound into the minor groove of DNA duplex.

  11. On polarization in biomembranes

    DEFF Research Database (Denmark)

    Zecchi, Karis Amata

    close to physiological conditions, making these effects biologically relevant. In this work, we consider the case of asymmetric membranes which can display spontaneous polarization in the absence of a field. Close to the phase transition, we find that the membrane displays piezoelectric, flexoelectric...... and thermoelectric behaviour. In particular, the membrane capacitance is a nonlinear function of the applied voltage. Furthermore, in the presence of spontaneous polarization, our thermodynamical description is able to explain the outward rectified current-voltage relationship measured on synthetic lipid bilayers....... Due to the nonlinear dependence of the membrane capacitance and conductance on voltage and the presence of spontaneous polarization, the traditional equivalent circuit of the membrane is not an accurate description in physiological conditions. An updated equivalent circuit of the lipid bilayer is here...

  12. A lunar polar expedition

    Science.gov (United States)

    Dowling, Richard; Staehle, Robert L.; Svitek, Tomas

    1992-01-01

    Advanced exploration and development in harsh environments require mastery of basic human survival skill. Expeditions into the lethal climates of Earth's polar regions offer useful lessons for tommorrow's lunar pioneers. In Arctic and Antarctic exploration, 'wintering over' was a crucial milestone. The ability to establish a supply base and survive months of polar cold and darkness made extensive travel and exploration possible. Because of the possibility of near-constant solar illumination, the lunar polar regions, unlike Earth's may offer the most hospitable site for habitation. The World Space Foundation is examining a scenario for establishing a five-person expeditionary team on the lunar north pole for one year. This paper is a status report on a point design addressing site selection, transportation, power, and life support requirements.

  13. Polarized Light from Jupiter

    Science.gov (United States)

    2001-01-01

    These images taken through the wide angle camera near closest approach in the deep near-infrared methane band, combined with filters which sense electromagnetic radiation of orthogonal polarization, show that the light from the poles is polarized. That is, the poles appear bright in one image, and dark in the other. Polarized light is most readily scattered by aerosols. These images indicate that the aerosol particles at Jupiter's poles are small and likely consist of aggregates of even smaller particles, whereas the particles at the equator and covering the Great Red Spot are larger. Images like these will allow scientists to ascertain the distribution, size and shape of aerosols, and consequently, the distribution of heat, in Jupiter's atmosphere.

  14. No More Polarization, Please!

    DEFF Research Database (Denmark)

    Hansen, Mia Reinholt

    The organizational science literature on motivation has for long been polarized into two main positions; the organizational economic position focusing on extrinsic motivation and the organizational behavior position emphasizing intrinsic motivation. With the rise of the knowledge economy...... and the increasing levels of complexities it entails, such polarization is not fruitful in the attempt to explain motivation of organizational members. This paper claims that a more nuanced perspective on motivation, acknowledging the co-existence of intrinsic and extrinsic motivation, the possible interaction...... between the two as well as different types of motivations filling in the gap between the two polar types, is urgently needed in the organizational science literature. By drawing on the research on intrinsic and extrinsic motivation conducted in social psychology and combining this with contributions from...

  15. [Polar body diagnosis].

    Science.gov (United States)

    Montag, M; van der Ven, K; van der Ven, H

    2009-01-01

    Polar body diagnosis (PBD) is a diagnostic method for the indirect genetic analysis of oocytes. Polar bodies are by-products of the meiotic cell cycle which have no influence on further embryo development. The biopsy of polar bodies can be accomplished either by zona drilling or laser drilling within a very short time period. The paternal contribution to the genetic constitution of the developing embryo cannot be diagnosed by PBD. The major application of PBD is the detection of maternally derived chromosomal aneuploidies and translocations in oocytes. For these indications, PBD may offer a viable alternative to blastomere biopsy as the embryo's integrity remains unaffected in contrast to preimplantation genetic diagnosis by blastomere biopsy. The fast development in the field of molecular diagnostics will also influence PBD and probably allow a more general diagnosis in the future.

  16. POLARIZED NEUTRONS IN RHIC

    Energy Technology Data Exchange (ETDEWEB)

    COURANT,E.D.

    1998-04-27

    There does not appear to be any obvious way to accelerate neutrons, polarized or otherwise, to high energies by themselves. To investigate the behavior of polarized neutrons the authors therefore have to obtain them by accelerating them as components of heavier nuclei, and then sorting out the contribution of the neutrons in the analysis of the reactions produced by the heavy ion beams. The best neutron carriers for this purpose are probably {sup 3}He nuclei and deuterons. A polarized deuteron is primarily a combination of a proton and a neutron with their spins pointing in the same direction; in the {sup 3}He nucleus the spins of the two protons are opposite and the net spin (and magnetic moment) is almost the same as that of a free neutron. Polarized ions other than protons may be accelerated, stored and collided in a ring such as RHIC provided the techniques proposed for polarized proton operation can be adapted (or replaced by other strategies) for these ions. To accelerate polarized particles in a ring, one must make provisions for overcoming the depolarizing resonances that occur at certain energies. These resonances arise when the spin tune (ratio of spin precession frequency to orbit frequency) resonates with a component present in the horizontal field. The horizontal field oscillates with the vertical motion of the particles (due to vertical focusing); its frequency spectrum is dominated by the vertical oscillation frequency and its modulation by the periodic structure of the accelerator ring. In addition, the magnet imperfections that distort the closed orbit vertically contain all integral Fourier harmonics of the orbit frequency.

  17. APD detectors for biological fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mazeres, S. [Institut de Pharmacologie et de Biologie Structurale, IPBS-CNRS, 205 route de Narbonne 31077 Toulouse Cedex 4 (France)]. E-mail: serge.mazeres@ipbs.fr; Borrel, V. [GIATHE/CESR, 9 avenue du Colonel Roche BP 4346, 31029 Toulouse Cedex (France); Magenc, C. [GIATHE/CESR, 9 avenue du Colonel Roche BP 4346, 31029 Toulouse Cedex (France); Courrech, J.L. [GIATHE/CESR, 9 avenue du Colonel Roche BP 4346, 31029 Toulouse Cedex (France); Bazer-Bachi, R. [GIATHE/CESR, 9 avenue du Colonel Roche BP 4346, 31029 Toulouse Cedex (France)

    2006-11-01

    Fluorescence spectroscopy is a very convenient and widely used method for studying the molecular background of biological processes [L. Salome, J.L. Cazeil, A. Lopez, J.F. Tocanne, Eur. Biophys. J. 27 (1998) 391-402]. Chromophores are included in the structure under study and a flash of laser light induces fluorescence (Fluorescence Recovery After Photo-bleaching), the decay of which yields information on the polarity, the speed of rotation, and the speed of diffusion as well as on the temporal and spatial evolution of interactions between molecular species. The method can even be used to study living cells [J.F. Tocanne, L. Cezanne, A. Lopez, Prog. Lipid Res. 33 (1994) 203-237, L. Cezanne, A. Lopez, F. Loste, G. Parnaud, O. Saurel, P. Demange, J.F. Tocanne, Biochemistry 38 (1999) 2779-2786]. This is classically performed with a PM-based system. For biological reasons a decrease of the excitation of the cells is highly desirable. Because the fluorescence response then becomes fainter a significant improvement in detector capability would be welcome. We present here results obtained with an Avalanche Photo Diode (APD)-based system. The small sensitive area of detection allows a very significant improvement in signal/noise ratio, improvement in gain, and the opening-up of a new parameter space. With these new detectors we can begin the study of information transmission between cells through morphine receptors. This work involves both electronics engineers and biophysicists, so results and techniques in both fields will be presented here.

  18. Validação interlaboratorial do teste de polarização fluorescente para o diagnóstico sorológico da brucelose bovina Interlaboratorial validation of the fluorescence polarization assay for the serodiagnosis of bovine brucellosis

    Directory of Open Access Journals (Sweden)

    Luis Antonio Mathias

    2010-10-01

    Full Text Available Esta investigação teve por objetivo validar o teste de polarização fluorescente (TPF para o diagnóstico sorológico da brucelose bovina, determinando a sensibilidade (SE e a especificidade relativas (SP e verificando a reprodutibilidade do teste em quatro laboratórios no Brasil. Foram selecionadas 1.389 amostras de soro sanguíneo, as quais foram inicialmente submetidas aos testes do antígeno acidificado tamponado (AAT e mercaptoetanol (2-ME. As mesmas amostras foram submetidas à reação de fixação de complemento (RFC e ao TPF. Para a avaliação do TPF, foi adotada a combinação dos resultados do AAT, da RFC e do 2-ME, utilizados como população de referência (padrão-ouro. Para a determinação do ponto de corte do TPF que proporciona a melhor combinação de sensibilidade e especificidade, foi usada a análise TG-ROC. A concordância entre os resultados dos quatro laboratórios foi determinada com base no indicador kappa e no coeficiente de correlação de Pearson. Os pontos de corte do TPF situaram-se entre 85,2 e 93,6 mP, conforme o laboratório. A sensibilidade variou de 91,7 a 97,3%, e a especificidade situou-se na faixa de 82,6 a 98,3%. Na comparação entre os resultados do TPF dos quatro laboratórios, o indicador kappa ficou entre 0,69 e 0,95, o que indica, na maioria das situações, reprodutibilidade excelente, e o coeficiente de correlação variou entre 0,76 e 0,99. Os resultados indicaram que o TPF apresentou bom desempenho, na maioria das situações, com sensibilidade e especificidade elevadas. Em comparação com os testes convencionais, o TPF apresenta as vantagens de ser de execução mais rápida e mais fácil e não estar sujeito à ocorrência de prozona, como a RFC e o 2-ME, nem de atividade anticomplementar, como a RFC.The purpose of this research was the interlaboratorial validation of the polarization fluorescence assay (PFA for the serodiagnosis of bovine brucellosis, verifying the relative sensitivity

  19. 荧光偏振技术研究Bloom解旋酶催化核心与双链DNA的相互作用%Study on The Interactions of Bloom Helicase Catalytic Core With Double-Stranded DNA by Fluorescence Polarization Technology

    Institute of Scientific and Technical Information of China (English)

    骆衡; 许厚强; 陈祥; 刘朝前; 许庆贺; 李坤

    2013-01-01

    Bloom综合症(BLM)解旋酶是RecQ家族DNA解旋酶中的一个重要成员,参与了DNA复制、修复、转录、重组以及端粒的维持等细胞代谢过程,在维持染色体的稳定性中具有重要的作用.BLM解旋酶的突变可导致Bloom综合症,患者遗传不稳定易患多种类型癌症.本研究运用荧光偏振技术研究BLM解旋酶催化核心(BLM642~1290)与双链DNA(dsDNA)的相互作用,分析其相关特征参数,了解BLM642~1290解旋酶与dsDNA的结合和解链特性.结果表明:BLM642~1290解旋酶与dsDNA的结合和解链与dsDNA 3'端的单链DNA(ssDNA)长度有关;解旋酶优先结合于dsDNA底物的ssDNA末端,且每分子解旋酶可结合9.6 nt的ssDNA; dsDNA 3'端ssDNA的长度为9.6 nt时,解旋酶的解链效率达到最大且不再随其长度而变化.另外,BLM642~1290解旋酶也能够结合和解链钝末端dsDNA,但其结合亲和力和解链效率低子有3'端ssDNA的dsDNA.推测BLM642~1290解旋酶在与dsDNA底物结合和解链时是单体形式,可能以尺蠖的形式解开dsDNA.这些结果可为进一步研究BLM解旋酶的功能特征提供理论基础.%Bloom syndrome helicase (BLM) is an important member of RecQ family of DNA helicases. It participates in cell metabolism including DNA repair, recombination, transcription, telomere maintenance, and plays key roles in maintaining chromosome stability. The mutation of BLM helicase may lead to Bloom syndrome that characterized by genomic instability and a strong predisposition to many types of cancer. This study was studied the interaction of BLM helicase catalytic core (BLM642 ~1290) with double-stranded DNA (dsDNA) by fluorescence polarization technology, and analyzed the related characteristic parameters to understand the DNA-binding and unwinding properties of BLM642 ~1290 helicase. The results indicated that the binding and unwinding of the helicase and dsDNA was related to the length of 3'-tailed single-stranded DNA (ssDNA) in ds

  20. Microwave Frequency Polarizers

    Science.gov (United States)

    Ha, Vien The; Mirel, Paul; Kogut, Alan J.

    2013-01-01

    This article describes the fabrication and analysis of microwave frequency polarizing grids. The grids are designed to measure polarization from the cosmic microwave background. It is effective in the range of 500 to 1500 micron wavelength. It is cryogenic compatible and highly robust to high load impacts. Each grid is fabricated using an array of different assembly processes which vary in the types of tension mechanisms to the shape and size of the grids. We provide a comprehensive study on the analysis of the grids' wire heights, diameters, and spacing.

  1. Internal polarized targets

    Energy Technology Data Exchange (ETDEWEB)

    Kinney, E.R.; Coulter, K.; Gilman, R.; Holt, R.J.; Kowalczyk, R.S.; Napolitano, J.; Potterveld, D.H.; Young, L. (Argonne National Lab., IL (USA)); Mishnev, S.I.; Nikolenko, D.M.; Popov, S.G.; Rachek, I.A.; Temnykh, A.B.; Toporkov, D.K.; Tsentalovich, E.P.; Wojtsekhowski, B.B. (AN SSSR, Novosibirsk (USSR). Inst. Yadernoj Fiziki)

    1989-01-01

    Internal polarized targets offer a number of advantages over external targets. After a brief review of the basic motivation and principles behind internal polarized targets, the technical aspects of the atomic storage cell will be discussed in particular. Sources of depolarization and the means by which their effects can be ameliorated will be described, especially depolarization by the intense magnetic fields arising from the circulating particle beam. The experience of the Argonne Novosibirsk collaboration with the use of a storage cell in a 2 GeV electron storage ring will be the focus of this technical discussion. 17 refs., 11 figs.

  2. New compact neutron polarizer

    Science.gov (United States)

    Krist, Th; Kennedy, S. J.; Hicks, T. J.; Mezei, F.

    A new type of a neutron polarizing bender was developed in co-operation with BENSC and ANSTO. It is based upon bent thin silicon wafers coated on one side with SiFeCo polarizing supermirrors and on the other side with Gd. Initial tests at BENSC in a 300 Oe magnetic field yielded a transmission of spin-up neutrons of about 55% over an angle range of 0.75° and flipping ratios > 30. Subsequent tests at ANSTO at 1200 Oe yielded a transmission of 48% with a flipping ratio > 45.

  3. The physics of polarization

    Science.gov (United States)

    Landi Degl'Innocenti, Egidio

    This course is intended to give a description of the basic physical concepts which underlie the study and the interpretation of polarization phenomena. Apart from a brief historical introduction (Sect. 1), the course is organized in three parts. A first part (Sects. 2 - 6) covers the most relevant facts about the polarization phenomena that are typically encountered in laboratory applications and in everyday life. In Sect. 2, the modern description of polarization in terms of the Stokes parameters is recalled, whereas Sect. 3 is devoted to introduce the basic tools of laboratory polarimetry, such as the Jones calculus and the Mueller matrices. The polarization phenomena which are met in the reflection and refraction of a beam of radiation at the separation surface between two dielectrics, or between a dielectric and a metal, are recalled in Sect. 4. Finally, Sect. 5 gives an introduction to the phenomena of dichroism and of anomalous dispersion and Sect. 6 summarizes the polarization phenomena that are commonly encountered in everyday life. The second part of this course (Sects. 7-14) deals with the description, within the formalism of classical physics, of the spectro-polarimetric properties of the radiation emitted by accelerated charges. Such properties are derived by taking as starting point the Liénard and Wiechert equations that are recalled and discussed in Sect. 7 both in the general case and in the non-relativistic approximation. The results are developed to find the percentage polarization, the radiation diagram, the cross-section and the spectral characteristics of the radiation emitted in different phenomena particularly relevant from the astrophysical point of view. The emission of a linear antenna is derived in Sect. 8. The other Sections are devoted to Thomson scattering (Sect. 9), Rayleigh scattering (Sect. 10), Mie scattering (Sect. 11), bremsstrahlung radiation (Sect. 12), cyclotron radiation (Sect. 13), and synchrotron radiation (Sect. 14

  4. Synthesis and Fluorescence Spectra of Triazolylcoumarin Fluorescent Dyes

    Institute of Scientific and Technical Information of China (English)

    PENG Xian-fu; LI Hong-qi

    2009-01-01

    Much attention is devoted to fluorescent dyes especially those with potential in versatile applications. Reactions under "click" conditions between nonfluorescent 3 - azidocoumarins and terminal alkynes produced 3 -(1, 2, 3- triazol- 1 - yl)cournarins, a novel type of fluorescent dyes with intense fluorescence. The structures of the new coumarins were characterized by 1H NMR, MS, and IR spectra. Fluorescence spectra measurement demonstrated excellent fluorescence performance of the triazolylcoumarins and this click reaction is a promising candidate for bioconjugation and bioimaging applications since both azide and alkynes are quite inert to biological systems.

  5. Fluorescence nanoscopy. Methods and applications

    OpenAIRE

    Requejo-Isidro, Jose

    2013-01-01

    Fluorescence nanoscopy refers to the experimental techniques and analytical methods used for fluorescence imaging at a resolution higher than conventional, diffraction-limited, microscopy. This review explains the concepts behind fluorescence nanoscopy and focuses on the latest and promising developments in acquisition techniques, labelling strategies to obtain highly detailed super-resolved images and in the quantitative methods to extract meaningful information from them.

  6. Prostate Cancer Detection Using Near Infrared Spectral Polarization Imaging

    Science.gov (United States)

    2005-07-01

    Distribution Unlimited 13. SUPPLEMENTARY NOTES Original contains color plates: ALL DTIC reproductions will be in black and white 14. ABSTRACT Abstract follows...flower and the anthocyanin pigments extracted from Streptocarpus holstii and Anthuriumn andreanum were performed in our lab [13]. The results show that the...P. Sekuler and R. R. Alfano, "Picosecond fluorescence kinetics and polarization anisotropy from anthocyanin pigment", Photobiochemistry and

  7. Polarized Proton Collisions at RHIC

    CERN Document Server

    Bai, Mei; Alekseev, Igor G; Alessi, James; Beebe-Wang, Joanne; Blaskiewicz, Michael; Bravar, Alessandro; Brennan, Joseph M; Bruno, Donald; Bunce, Gerry; Butler, John J; Cameron, Peter; Connolly, Roger; De Long, Joseph; Drees, Angelika; Fischer, Wolfram; Ganetis, George; Gardner, Chris J; Glenn, Joseph; Hayes, Thomas; Hseuh Hsiao Chaun; Huang, Haixin; Ingrassia, Peter; Iriso, Ubaldo; Laster, Jonathan S; Lee, Roger C; Luccio, Alfredo U; Luo, Yun; MacKay, William W; Makdisi, Yousef; Marr, Gregory J; Marusic, Al; McIntyre, Gary; Michnoff, Robert; Montag, Christoph; Morris, John; Nicoletti, Tony; Oddo, Peter; Oerter, Brian; Osamu, Jinnouchi; Pilat, Fulvia Caterina; Ptitsyn, Vadim; Roser, Thomas; Satogata, Todd; Smith, Kevin T; Svirida, Dima; Tepikian, Steven; Tomas, Rogelio; Trbojevic, Dejan; Tsoupas, Nicholaos; Tuozzolo, Joseph; Vetter, Kurt; Wilinski, Michelle; Zaltsman, Alex; Zelenski, Anatoli; Zeno, Keith; Zhang, S Y

    2005-01-01

    The Relativistic Heavy Ion Collider~(RHIC) provides not only collisions of ions but also collisions of polarized protons. In a circular accelerator, the polarization of polarized proton beam can be partially or fully lost when a spin depolarizing resonance is encountered. To preserve the beam polarization during acceleration, two full Siberian snakes were employed in RHIC to avoid depolarizing resonances. In 2003, polarized proton beams were accelerated to 100~GeV and collided in RHIC. Beams were brought into collisions with longitudinal polarization at the experiments STAR and PHENIX by using spin rotators. RHIC polarized proton run experience demonstrates that optimizing polarization transmission efficiency and improving luminosity performance are significant challenges. Currently, the luminosity lifetime in RHIC is limited by the beam-beam effect. The current state of RHIC polarized proton program, including its dedicated physics run in 2005 and efforts to optimize luminosity production in beam-beam limite...

  8. Influence of angle's ranges for recording an X-ray fluorescence hologram on reconstructed atomic images

    Institute of Scientific and Technical Information of China (English)

    XIE Hong-Lan; CHEN Jian-Wen; GAO Hong-Yi; ZHU Hua-Feng; LI Ru-Xin; XU Zhi-Zhan

    2004-01-01

    X-ray fluorescence holography (XFH) is a novel method for three-dimensional (3D) imaging of atomic structure. Theoretically, in an XFH experiment, one has to measure the fluorescence energy on a spherical surface to get well-resolved 3D images of atoms. But in practice, the experimental system arrangement does not allow the measurement of the fluorescent intensity oscillations in the full sphere. The holographic information losses because of the limited sampling range (less than 4π) will directly result in defective reconstructed atomic images. In this work, the atomic image of a Fe single crystal (001) was reconstructed by numerically simulating X-ray fluorescence holograms of the crystal at different recording angle's ranges and step lengths. Influences of the ranges of azimuth angles and polar angles and the step length of polar angles on the reconstructed atomic images were discussed.

  9. Naphthatimide as Highly Selective Fluorescent Sensor for Ag+ Ions

    Institute of Scientific and Technical Information of China (English)

    XU,Sheng; LI,Wei; CHEN,Kong-Chang

    2007-01-01

    The naphthalimide derivative NA1 was synthesized, which consists of a bis(2-(ethylthio)ethyl)amine group binding cations and naphthalimide unit as chromogenic and fluorogenic signaling subunit. Absorption and emission spectra and the effect of polarity of solvents and pH values were studied. The photo-induced electron transfer (PET) occurred from the donor of bis(2-(ethylthio)ethyl)amine group to the naphthalimide fluorophore. The present study demonstrates that NA1 is a viable candidate as a fluorescent receptor for a new Ag+ ion sensor. This silver ion chemosensor can discriminate Ag+ ion well among heavy metal ions by an enhancement of the fluorescence intensity in ethanol-water (1:9, V:V). And NA1 is also a pH-sensor because the fluorescence of the compound varies with the pH values.

  10. Variable polarity arc welding

    Science.gov (United States)

    Bayless, E. O., Jr.

    1991-01-01

    Technological advances generate within themselves dissatisfactions that lead to further advances in a process. A series of advances in welding technology which culminated in the Variable Polarity Plasma Arc (VPPA) Welding Process and an advance instituted to overcome the latest dissatisfactions with the process: automated VPPA welding are described briefly.

  11. Titan Polar Landscape Evolution

    Science.gov (United States)

    Moore, Jeffrey M.

    2016-01-01

    With the ongoing Cassini-era observations and studies of Titan it is clear that the intensity and distribution of surface processes (particularly fluvial erosion by methane and Aeolian transport) has changed through time. Currently however, alternate hypotheses substantially differ among specific scenarios with respect to the effects of atmospheric evolution, seasonal changes, and endogenic processes. We have studied the evolution of Titan's polar region through a combination of analysis of imaging, elevation data, and geomorphic mapping, spatially explicit simulations of landform evolution, and quantitative comparison of the simulated landscapes with corresponding Titan morphology. We have quantitatively evaluated alternate scenarios for the landform evolution of Titan's polar terrain. The investigations have been guided by recent geomorphic mapping and topographic characterization of the polar regions that are used to frame hypotheses of process interactions, which have been evaluated using simulation modeling. Topographic information about Titan's polar region is be based on SAR-Topography and altimetry archived on PDS, SAR-based stereo radar-grammetry, radar-sounding lake depth measurements, and superposition relationships between geomorphologic map units, which we will use to create a generalized topographic map.

  12. Saturn's Polar Atmosphere

    CERN Document Server

    Sayanagi, Kunio M; Dyudina, Ulyana A; Fletcher, Leigh N; Sánchez-Lavega, Agustin; West, Robert A

    2016-01-01

    This book chapter, Saturn's Polar Atmosphere, is to be published by Cambridge University Press as part of a multi-volume work edited by Kevin Baines, Michael Flasar, Norbert Krupp, and Thomas Stallard, entitled "Saturn in the 21st Century." This chapter reviews the state of our knowledge about Saturn's polar atmosphere that has been revealed through Earth- and space-based observation as well as theoretical and numerical modeling. In particular, the Cassini mission to Saturn, which has been in orbit around the ringed planet since 2004, has revolutionized our understanding of the planet. The current review updates a previous review by Del Genio et al (2009; Saturn Atmospheric Structure and Dynamics, Chapter 7 of "Saturn from Cassini-Huygens"), written after Cassini's primary mission phase that ended in 2008, by focusing on the north polar region of Saturn and comparing it to the southern high latitudes. Two prominent features in the northern high latitudes are the northern hexagon and the north polar vortex; we...

  13. Polarized parton distributions

    Energy Technology Data Exchange (ETDEWEB)

    de Florian, D.; Epele, L.N.; Fanchiotti, H.; Garcia Canal, C.A.; Sassot, R. (Laboratorio de Fisica Teorica, Departamento de Fisica, Universidad Nacional de La Plata, C.C. 67-1900 La Plata (Argentina))

    1995-01-01

    We analyze spin-dependent parton distributions consistent with the most recent measurements of the spin-dependent deep inelastic scattering structure functions and obtained in the framework of the spin dilution model. Predictions for the doubly polarized proton-proton Drell-Yan asymmetry, for the high [ital p][sub [ital T

  14. Delayed fluorescence in photosynthesis.

    Science.gov (United States)

    Goltsev, Vasilij; Zaharieva, Ivelina; Chernev, Petko; Strasser, Reto J

    2009-01-01

    Photosynthesis is a very efficient photochemical process. Nevertheless, plants emit some of the absorbed energy as light quanta. This luminescence is emitted, predominantly, by excited chlorophyll a molecules in the light-harvesting antenna, associated with Photosystem II (PS II) reaction centers. The emission that occurs before the utilization of the excitation energy in the primary photochemical reaction is called prompt fluorescence. Light emission can also be observed from repopulated excited chlorophylls as a result of recombination of the charge pairs. In this case, some time-dependent redox reactions occur before the excitation of the chlorophyll. This delays the light emission and provides the name for this phenomenon-delayed fluorescence (DF), or delayed light emission (DLE). The DF intensity is a decreasing polyphasic function of the time after illumination, which reflects the kinetics of electron transport reactions both on the (electron) donor and the (electron) acceptor sides of PS II. Two main experimental approaches are used for DF measurements: (a) recording of the DF decay in the dark after a single turnover flash or after continuous light excitation and (b) recording of the DF intensity during light adaptation of the photosynthesizing samples (induction curves), following a period of darkness. In this paper we review historical data on DF research and recent advances in the understanding of the relation between the delayed fluorescence and specific reactions in PS II. An experimental method for simultaneous recording of the induction transients of prompt and delayed chlorophyll fluorescence and decay curves of DF in the millisecond time domain is discussed.

  15. Polarized nuclear target based on parahydrogen induced polarization

    Energy Technology Data Exchange (ETDEWEB)

    Budker, D., E-mail: dbudker@gmail.com [Department of Physics, University of California at Berkeley, Berkeley, CA 94720-7300 (United States); Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Ledbetter, M.P. [Department of Physics, University of California at Berkeley, Berkeley, CA 94720-7300 (United States); Appelt, S. [Central Institute for Electronics, Research Center Juelich, D-52425 Juelich (Germany); Bouchard, L.S. [Department of Chemistry and Biochemistry, California NanoSystems Institute, Biomedical Engineering IDP, Jonsson Comprehensive Cancer Center, University of California, Los Angeles, CA 90095 (United States); Wojtsekhowski, B. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States)

    2012-12-01

    We discuss a novel concept of a polarized nuclear target for accelerator fixed-target scattering experiments, which is based on parahydrogen induced polarization (PHIP). One may be able to reach a 33% free-proton polarization in the ethane molecule. The potential advantages of such a target include operation at zero magnetic field, fast ({approx}100Hz) polarization oscillation (akin to polarization reversal), and operation with large intensity of an electron beam. -- Highlights: Black-Right-Pointing-Pointer Novel concept for polarized nuclear targets. Black-Right-Pointing-Pointer The target features fast reversal and operates at near-zero magnetic field. Black-Right-Pointing-Pointer Based on the technique of parahydrogen induced polarization that is revolutionizing NMR and enables NMR/MRI without magnets. Black-Right-Pointing-Pointer Competitive figure-of-merit for polarized targets.

  16. Bimodal Distribution and Fluorescence Response of Environment-Sensitive Probes in Lipid Bilayers

    OpenAIRE

    Klymchenko, Andrey S; Duportail, Guy; Demchenko, Alexander P.; Mély, Yves

    2004-01-01

    A remarkable heterogeneity is often observed in the spectroscopic properties of environment-sensitive fluorescence probes in phospholipid bilayers. To explain its origin, we provided a detailed investigation of the fluorescence excitation and emission spectra of 4′-dimethylamino-3-hydroxyflavone (probe F) in bilayer vesicles with the variations of fatty acid composition, polar heads, temperature, and cholesterol content. Probe F, due to excited-state intramolecular proton transfer, exhibits t...

  17. Dynacortin facilitates polarization of chemotaxing cells

    Directory of Open Access Journals (Sweden)

    Reichl Elizabeth M

    2007-11-01

    Full Text Available Abstract Background Cell shape changes during cytokinesis and chemotaxis require regulation of the actin cytoskeletal network. Dynacortin, an actin cross-linking protein, localizes to the cell cortex and contributes to cortical resistance, thereby helping to define the cell shape changes of cytokinesis. Dynacortin also becomes highly enriched in cortical protrusions, which are sites of new actin assembly. Results We studied the effect of dynacortin on cell motility during chemotaxis and on actin dynamics in vivo and in vitro. Dynacortin enriches with the actin, particularly at the leading edge of chemotaxing cells. Cells devoid of dynacortin do not become as polarized as wild-type control cells but move with similar velocities as wild-type cells. In particular, they send out multiple pseudopods that radiate at a broader distribution of angles relative to the chemoattractant gradient. Wild-type cells typically only send out one pseudopod at a time that does not diverge much from 0° on average relative to the gradient. Though dynacortin-deficient cells show normal bulk (whole-cell actin assembly upon chemoattractant stimulation, dynacortin can promote actin assembly in vitro. By fluorescence spectroscopy, co-sedimentation and transmission electron microscopy, dynacortin acts as an actin scaffolder in which it assembles actin monomers into polymers with a stoichiometry of 1 Dyn2:1 actin under salt conditions that disfavor polymer assembly. Conclusion Dynacortin contributes to cell polarization during chemotaxis. By cross-linking and possibly stabilizing actin polymers, dynacortin also contributes to cortical viscoelasticity, which may be critical for establishing cell polarity. Though not essential for directional sensing or motility, dynacortin is required to establish cell polarity, the third core feature of chemotaxis.

  18. NUCLEON POLARIZATION IN 3-BODY MODELS OF POLARIZED LI-6

    NARCIS (Netherlands)

    SCHELLINGERHOUT, NW; KOK, LP; COON, SA; ADAM, RM

    1993-01-01

    Just as He-3 --> can be approximately characterized as a polarized neutron target, polarized Li-6D has been advocated as a good isoscalar nuclear target for the extraction of the polarized gluon content of the nucleon. The original argument rests upon a presumed ''alpha + deuteron'' picture of Li-6,

  19. NUCLEON POLARIZATION IN 3-BODY MODELS OF POLARIZED LI-6

    NARCIS (Netherlands)

    SCHELLINGERHOUT, NW; KOK, LP; COON, SA; ADAM, RM

    1993-01-01

    Just as He-3 --> can be approximately characterized as a polarized neutron target, polarized Li-6D has been advocated as a good isoscalar nuclear target for the extraction of the polarized gluon content of the nucleon. The original argument rests upon a presumed ''alpha + deuteron'' picture of Li-6,

  20. Thermal quenching of fluorescence in condensed media

    Science.gov (United States)

    Lagos, Miguel; Paredes, Rodrigo

    2016-09-01

    Environmental factors strongly affect the features of the electromagnetic spectra of fluorescent compounds hosted by material media. The shape of the absorption and emission peaks, their characteristic asymmetry and breadth, the Stokes shift and quantum yield are generally temperature dependent and heavily influenced by both the local and extended physical properties of the medium. The theoretical method used before to obtain the lineshape function is extended here to other terms of the interaction energy between the optically sensitive orbital and the hosting medium, which become significant when the spectral feature is broad. An analytical expression for the temperature dependent decay rate by non-radiative processes is obtained by this way. Comparison with experiment on thermal quenching gives agreement within the experimental uncertainty. The solvent polarity, its protic or aprotic character, hydrogen bonds, proximity effects and presence of quenchers are expected to enter through the coupling constants of the corresponding energy terms.

  1. North Polar Cap

    Science.gov (United States)

    2004-01-01

    [figure removed for brevity, see original site] This week we will be looking at five examples of laminar wind flow on the north polar cap. On Earth, gravity-driven south polar cap winds are termed 'catabatic' winds. Catabatic winds begin over the smooth expanse of the cap interior due to temperature differences between the atmosphere and the surface. Once begun, the winds sweep outward along the surface of the polar cap toward the sea. As the polar surface slopes down toward sealevel, the wind speeds increase. Catabatic wind speeds in the Antartic can reach several hundreds of miles per hour. In the images of the Martian north polar cap we can see these same type of winds. Notice the streamers of dust moving downslope over the darker trough sides, these streamers show the laminar flow regime coming off the cap. Within the trough we see turbulent clouds of dust, kicked up at the trough base as the winds slow down and enter a chaotic flow regime. The horizontal lines in these images are due to framelet overlap and lighting conditions over the bright polar cap. Image information: VIS instrument. Latitude 86.5, Longitude 64.5 East (295.5 West). 40 meter/pixel resolution. Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen

  2. Design of branched and chiral solvatochromic probes: toward quantifying polarity gradients in dendritic macromolecules.

    Science.gov (United States)

    Milosevic, Petar; Hecht, Stefan

    2005-10-27

    [reaction: see text] A pair of chiral, branched monomer building blocks, consisting of a solvatochromic probe and a spectroscopically inactive volume dummy, has been developed. The probe can selectively be excited, and its fluorescence characteristics provide information about local polarity. Incorporation of these monomers into high-generation polyester dendrimers should enable a detailed investigation of the polarity/density profile in dendritic architectures and ultimately allow for the realization of energy gradients from one chromophore building block only.

  3. Polarization singularity anisotropy: determining monstardom

    CERN Document Server

    Dennis, Mark R

    2008-01-01

    C points, that is isolated points of circular polarization in transverse fields of varying polarization, are classified morphologically into three distinct types, known as lemons, stars and monstars. These morphologies are interpreted here according to two natural parameters associated with the singularity, namely the anisotropy of the C point, and the polarization azimuth on the anisotropy axis. In addition to providing insight into singularity morphology, this observation applies to the densities of the various morphologies in isotropic random polarization speckle fields.

  4. Polarization of a Helium-Neon Laser.

    Science.gov (United States)

    Jones, Edwin R.

    1996-01-01

    Describes an experiment that involves measuring the intensity of laser light passed by a linear polarizer. Discusses polarization effects, orthogonal polarizations, instrumentation, and further experiments. (JRH)

  5. Planar cell polarity signaling: a common mechanism for cellular polarization.

    Science.gov (United States)

    Jenny, Andreas; Mlodzik, Marek

    2006-09-01

    Epithelial cells frequently display--in addition to the common apical-basolateral polarity--a polarization within the plane of the epithelium. This is commonly referred to as planar cell polarity (PCP) or tissue polarity. Examples of vertebrate PCP include epithelial patterning in the skin and inner ear, and also the morphogenetic movements of mesenchymal cells during convergent extension at gastrulation. In Drosophila, all adult epithelial structures of the cuticle are polarized within the plane. This review presents recent results and new insights into the molecular mechanisms underlying the establishment of PCP, and compares and contrasts the intriguing similarities between PCP signaling in Drosophila and vertebrates.

  6. When measured spin polarization is not spin polarization

    Energy Technology Data Exchange (ETDEWEB)

    Dowben, P A; Wu Ning; Binek, Christian, E-mail: pdowben@unl.edu [Department of Physics and Astronomy and the Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE 68588-0299 (United States)

    2011-05-04

    Spin polarization is an unusually ambiguous scientific idiom and, as such, is rarely well defined. A given experimental methodology may allow one to quantify a spin polarization but only in its particular context. As one might expect, these ambiguities sometimes give rise to inappropriate interpretations when comparing the spin polarizations determined through different methods. The spin polarization of CrO{sub 2} and Cr{sub 2}O{sub 3} illustrate some of the complications which hinders comparisons of spin polarization values. (viewpoint)

  7. When measured spin polarization is not spin polarization.

    Science.gov (United States)

    Dowben, P A; Wu, Ning; Binek, Christian

    2011-05-04

    Spin polarization is an unusually ambiguous scientific idiom and, as such, is rarely well defined. A given experimental methodology may allow one to quantify a spin polarization but only in its particular context. As one might expect, these ambiguities sometimes give rise to inappropriate interpretations when comparing the spin polarizations determined through different methods. The spin polarization of CrO(2) and Cr(2)O(3) illustrate some of the complications which hinders comparisons of spin polarization values. © 2011 IOP Publishing Ltd

  8. Measuring Polarization with DASI

    CERN Document Server

    Leitch, E M; Pryke, C L; Reddall, B; Sandberg, E S; Dragovan, M; Carlstrom, J E; Halverson, N W; Holzapfel, W L

    2002-01-01

    We describe an experiment to measure the polarization of the Cosmic Microwave Background (CMB) with the Degree Angular Scale Interferometer (DASI), a compact microwave interferometer optimized to detect CMB anisotropy at multipoles 140 to 900. The telescope has operated at the Amundsen-Scott South Pole research station since 2000 January. The telescope was retrofit as a polarimeter during the 2000--2001 austral summer, and throughout the 2001 and 2002 austral winters has made observations of the CMB with sensitivity to all four Stokes parameters. The telescope performance has been extensively characterized through observations of artificial sources, the Moon, and polarized and unpolarized Galactic sources. In 271 days of observation, DASI has differenced the CMB fluctuations in two fields to an rms noise level of 2.8 uK.

  9. Polarized electrogowdy spacetimes censored

    Energy Technology Data Exchange (ETDEWEB)

    Nungesser, Ernesto, E-mail: ernesto.nungesser@aei.mpg.d [Max-Planck-Institut fuer Gravitationsphysik, Albert-Einstein-Institut, Am Muehlenberg 1, 14476 Potsdam (Germany)

    2010-05-01

    A sketch of the proof of strong cosmic censorship is presented for a class of solutions of the Einstein-Maxwell equations, those with polarized Gowdy symmetry. A key element of the argument is the observation that by means of a suitable choice of variables the central equations in this problem can be written in a form where they are identical to the central equations for general (i.e. non-polarized) vacuum Gowdy spacetimes. Using this it is seen that the results of Ringstroem on strong cosmic censorship in the vacuum case have implications for the Einstein-Maxwell case. Working out the geometrical meaning of these analytical results leads to the main conclusion.

  10. Galactic Diffuse Polarized Emission

    Indian Academy of Sciences (India)

    Ettore Carretti

    2011-12-01

    Diffuse polarized emission by synchrotron is a key tool to investigate magnetic fields in the Milky Way, particularly the ordered component of the large scale structure. Key observables are the synchrotron emission itself and the RM is by Faraday rotation. In this paper the main properties of the radio polarized diffuse emission and its use to investigate magnetic fields will be reviewed along with our current understanding of the galactic magnetic field and the data sets available. We will then focus on the future perspective discussing RM-synthesis – the new powerful instrument devised to unlock the information encoded in such an emission – and the surveys currently in progress like S-PASS and GMIMS.

  11. Polarization Diffusion from Spacetime Uncertainty

    CERN Document Server

    Contaldi, Carlo; Philpott, Lydia

    2010-01-01

    A model of Lorentz invariant random fluctuations in photon polarization is presented. The effects are frequency dependent and affect the polarization of photons as they propagate through space. We test for this effect by confronting the model with the latest measurements of polarization of Cosmic Microwave Background (CMB) photons.

  12. Alternating-Polarity Arc Welding

    Science.gov (United States)

    Schwinghamer, R. J.

    1987-01-01

    Brief reversing polarity of welding current greatly improves quality of welds. NASA technical memorandum recounts progress in art of variable-polarity plasma-arc (VPPA) welding, with emphasis on welding of aluminum-alloy tanks. VPPA welders offer important advantages over conventional single-polarity gas/tungsten arc welders.

  13. Polarization losses in reflector antennas

    Science.gov (United States)

    Safak, M.; Yazgan, E.

    1985-08-01

    Various definitions for polarization-loss efficiency of Cassegrainian and front-fed reflectors are compared. The effects of flare angle, feed taper and the feed pattern asymmetry on the polarization-loss efficiency are investigated. The definitions based on aperture fields are shown to be inadequate and far fields must be used for calculating the polarization losses.

  14. Two photon fluorescence imaging of lipid membrane domains and potentials using advanced fluorescent probes

    Science.gov (United States)

    Kilin, Vasyl; Darwich, Zeinab; Richert, Ludovic; Didier, Pascal; Klymchenko, Andrey; Mély, Yves

    2013-02-01

    Biomembranes are ordered and dynamic nanoscale structures critical for cell functions. The biological functions of the membranes strongly depend on their physicochemical properties, such as electrostatics, phase state, viscosity, polarity and hydration. These properties are essential for the membrane structure and the proper folding and function of membrane proteins. To monitor these properties, fluorescence techniques and notably, two-photon microscopy appear highly suited due to their exquisite sensitivity and their capability to operate in complex biological systems, such as living cells and tissues. In this context, we have developed multiparametric environment-sensitive fluorescent probes tailored for precise location in the membrane bilayer. We notably developed probes of the 3-hydroxychromone family, characterized by an excited state intramolecular proton transfer reaction, which generates two tautomeric emissive species with well-separated emission bands. As a consequence, the response of these probes to changes in their environment could be monitored through changes in the ratios of the two bands, as well as through changes in the fluorescence lifetimes. Using two-photon ratiometric imaging and FLIM, these probes were used to monitor the surface membrane potential, and were applied to detect apoptotic cells and image membrane domains.

  15. Transverse polarization in ; production

    Indian Academy of Sciences (India)

    Saurabh D Rindani

    2007-11-01

    With the use of transverse polarization (TP), a CP-odd and T-odd observable can be constructed when the final-state particles are self-conjugate. In the case of production, this observable can be used to probe a certain effective four-point + - CP-violating coupling, not accessible without TP. Effective CP-violating coupling does not contribute to this observable. A similar observable in production can be used to probe + - four-point couplings.

  16. Polarization induced doped transistor

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Huili (Grace); Jena, Debdeep; Nomoto, Kazuki; Song, Bo; Zhu, Mingda; Hu, Zongyang

    2016-06-07

    A nitride-based field effect transistor (FET) comprises a compositionally graded and polarization induced doped p-layer underlying at least one gate contact and a compositionally graded and doped n-channel underlying a source contact. The n-channel is converted from the p-layer to the n-channel by ion implantation, a buffer underlies the doped p-layer and the n-channel, and a drain underlies the buffer.

  17. PEPPo: Using a Polarized Electron Beam to Produce Polarized Positrons

    Energy Technology Data Exchange (ETDEWEB)

    Adeyemi, Adeleke H. [Hampton Univ., Hampton, VA (United States); et al.

    2015-09-01

    Polarized positron beams have been identified as either an essential or a significant ingredient for the experimental program of both the present and next generation of lepton accelerators (JLab, Super KEK B, ILC, CLIC). An experiment demonstrating a new method for producing polarized positrons has been performed at the Continuous Electron Beam Accelerator Facility at Jefferson Lab. The PEPPo (Polarized Electrons for Polarized Positrons) concept relies on the production of polarized e⁻/e⁺ pairs from the bremsstrahlung radiation of a longitudinally polarized electron beam interacting within a high-Z conversion target. PEPPo demonstrated the effective transfer of spin-polarization of an 8.2 MeV/c polarized (P~85%) electron beam to positrons produced in varying thickness tungsten production targets, and collected and measured in the range of 3.1 to 6.2 MeV/c. In comparison to other methods this technique reveals a new pathway for producing either high-energy or thermal polarized positron beams using a relatively low polarized electron beam energy (~10MeV) .This presentation will describe the PEPPo concept, the motivations of the experiment and high positron polarization achieved.

  18. Polar Business Design

    Directory of Open Access Journals (Sweden)

    Sébastien Caisse

    2014-02-01

    Full Text Available Polar business design aims to enable entrepreneurs, managers, consultants, researchers, and business students to better tackle model-based analysis, creation, and transformation of businesses, ventures, and, more generically, collective endeavors of any size and purpose. It is based on a systems-thinking approach that builds on a few interrelated core concepts to create holistic visual frameworks. These core concepts act as poles linked by meaningful dyads, flows, and faces arranged in geometric shapes. The article presents two such polar frameworks as key findings in an ongoing analytic autoethnography: the three-pole Value−Activity−Stakeholder (VAS triquetra and the four-pole Offer−Creation−Character−Stakeholder (OCCS tetrahedron. The VAS triquetra is a more aggregated model of collective endeavors. The OCCS tetrahedron makes a trade-off between a steeper learning curve and deeper, richer representation potential. This article discusses how to use these two frameworks as well as their limits, and explores the potential that polar business design offers for future research.

  19. Polarization properties of linearly polarized parabolic scaling Bessel beams

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Mengwen; Zhao, Daomu, E-mail: zhaodaomu@yahoo.com

    2016-10-07

    The intensity profiles for the dominant polarization, cross polarization, and longitudinal components of modified parabolic scaling Bessel beams with linear polarization are investigated theoretically. The transverse intensity distributions of the three electric components are intimately connected to the topological charge. In particular, the intensity patterns of the cross polarization and longitudinal components near the apodization plane reflect the sign of the topological charge. - Highlights: • We investigated the polarization properties of modified parabolic scaling Bessel beams with linear polarization. • We studied the evolution of transverse intensity profiles for the three components of these beams. • The intensity patterns of the cross polarization and longitudinal components can reflect the sign of the topological charge.

  20. Effect of ion pairing on the fluorescence of berberine, a natural isoquinoline alkaloid

    Science.gov (United States)

    Megyesi, Mónika; Biczók, László

    2007-10-01

    Effect of association with chloride or perchlorate anions on the fluorescence properties of berberine, a cationic isoquinoline alkaloid, has been studied. Interaction with Cl - caused more efficient fluorescence quenching; it significantly accelerated the radiationless deactivation and slowed down the radiative transition. Combined analysis of spectrophotometric, steady-state and time-resolved fluorescence results provided 1.5 × 10 5 M -1 for the equilibrium constant of ion pairing with Cl - in CH 2Cl 2. Both ion pairing and enrichment of the microenvironment of berberine in ions led to excited state quenching in solvents of medium polarity, but only the latter effect was observed in the presence of perchlorates in butyronitrile.

  1. Considerable fluorescence enhancement upon supramolecular complex formation between berberine and p-sulfonated calixarenes

    Science.gov (United States)

    Megyesi, Mónika; Biczók, László

    2006-06-01

    Remarkably strong binding of berberine to 4-sulfonatocalix[8]arene was found in aqueous solution, which led to fluorescence quantum yield increase of a factor about 40 at pH 2. The hypsochromic shift of the fluorescence maximum implied that berberine sensed less polar microenvironment when confined to SCX8. The stability of the supramolecular complex significantly diminished when sulfocalixarenes of smaller ring size served as host compounds but the pH affected the association strength to a much lesser extent. All berberine complexes proved to be barely fluorescent at pH 12.2 because of excited state quenching by the hosts via electron transfer.

  2. Standardization and quality assurance in fluorescence measurements I state-of-the art and future challenges

    CERN Document Server

    Resch-Genger, Ute

    2008-01-01

    The validation and standardization of fluorescence methods is still in its infancy as compared to other prominent analytical and bioanalytical methods. Appropriate quality assurance standards are however a prerequisite for applications in highly regulated fields such as medical diagnostics, drug development, or food analysis. For the first time, a team of recognized international experts has documented the present status of quality assurance in fluorescence measurements, and outlines concepts for establishing standards in this field. This first of two volumes covers basic aspects and various techniques such as steady-state and time-resolved fluorometry, polarization techniques, and fluorescent chemical sensors

  3. NIR fluorescent dyes: versatile vehicles for marker and probe applications

    Science.gov (United States)

    Patonay, Gabor; Chapman, Gala; Beckford, Garfield; Henary, Maged

    2013-02-01

    sulfonic acid moiety is modified to less water soluble moiety was identified. In polar solvents, these water soluble compounds are strongly fluorescent, however form the less soluble aggregated species with virtual loss of fluorescence when the sulfonate groups are cleaved by enzymatic activity to form the corresponding straight chain alkyl aldehyde derivatives. To achieve this conversion in vitro photo-reduced riboflavin mononucleotide (FMN) with a glucose/ glucose-oxygenase oxygen scavenging system was utilized. The reduced FMN serves as a key substrate in the enzymatic desulfonation. Once the FMNH2 was produced the desulfonation reaction was characterized by using Laser Induced Fluorescence Capillary Zone Electropheresis (LIF-CZE). This method can be utilized as an assay to detect the enzyme activity in vitro with the possibilities of in vivo applications.

  4. A novel carbazole-based fluorescent probe:3,6-Bis-[(N-ethylcarbazole-3-y1)-propene-1-keto]-N-ethylcarbazole

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A novel carbazole-based compound 5,3,6-bis[(N-ethylcarbazole-3-yl)-propene-1-keto]-N-ethylcarbazole has been designed, synthesized and characterized.The absorption and fluorescence spectra in solvents of different polarities prove that the compound has a distinct intramolecular charge transfer character.Compound 5 can be used as a new class of fluorescent probe or biosensor due to its sensitivity to the local microenvironment such as solvent polarity.

  5. M2 polarization enhances silica nanoparticle uptake by macrophages

    Directory of Open Access Journals (Sweden)

    Jessica eHoppstädter

    2015-03-01

    Full Text Available While silica nanoparticles have enabled numerous industrial and medical applications, their toxicological safety requires further evaluation. Macrophages are the major cell population responsible for nanoparticle clearance in vivo. The prevailing macrophage phenotype largely depends on the local immune status of the host. Whereas M1-polarized macrophages are considered as pro-inflammatory macrophages involved in host defense, M2 macrophages exhibit anti-inflammatory and wound-healing properties, but also promote tumor growth.We employed different models of M1 and M2 polarization: GM-CSF/LPS/IFN-gamma was used to generate primary human M1 cells and M-CSF/IL-10 to differentiate M2 monocyte-derived macrophages. PMA-differentiated THP-1 cells were polarized towards an M1 type by LPS/IFN-gamma and towards M2 by IL-10. Uptake of fluorescent silica nanoparticles (Ø 26 and 41 nm and microparticles (Ø 1.75 µm was quantified. At the concentration used (50 µg/ml, silica nanoparticles did not influence cell viability as assessed by MTT assay. Nanoparticle uptake was enhanced in M2-polarized primary human monocyte-derived macrophages compared with M1 cells, as shown by flow cytometric and microscopic approaches. In contrast, the uptake of microparticles did not differ between M1 and M2 phenotypes. M2 polarization was also associated with increased nanoparticle uptake in the macrophage-like THP-1 cell line. In accordance, in vivo polarized M2-like primary human tumor-associated macrophages (TAM obtained from lung tumors took up more nanoparticles than M1-like alveolar macrophages isolated from the surrounding lung tissue.In summary, our data indicate that the M2 polarization of macrophages promotes nanoparticle internalization. Therefore, the phenotypical differences between macrophage subsets should be taken into consideration in future investigations on nanosafety, but might also open up therapeutic perspectives allowing to specifically target M2

  6. Fluorescence properties of Laurdan in cochleate phases.

    Science.gov (United States)

    Ramani, Karthik; Balasubramanian, Sathyamangalam V

    2003-12-03

    Cochleates are lipid-based delivery system that have found application in drug and gene delivery. They are precipitates, formed as a result of interaction between cations (e.g. Ca2+) and negatively charged phospholipids such as phosphatidylserine (PS). In the present study, we investigated the utility of fluorescent probe Laurdan (6-dodecanoyl-2-dimethylamino naphthalene) to monitor cochleate phase formation. Following addition of Ca2+ to Laurdan labeled lipid vesicles comprised of brain phosphatidylserine (BPS), a significant blue shift in the emission peak maximum of Laurdan was observed and the spectral features were distinct from those observed for the gel and liquid-crystalline (LC) phases. This is consistent with the formation of anhydrous cochleate cylinders that was further confirmed by electron microscopy studies. Due to dipolar relaxation, excitation and emission generalized polarization (GPEx and GPEm) indicate transition from a LC to a rigid and dehydrated (RD) cochleate phase. These spectral changes were utilized to monitor the influence of lipid composition, ionic strength and lamellarity on the formation of cochleate phase. The results indicated that the presence of phosphatidylcholine (PC) and bulk Na+ concentration influenced the formation of cochleate structures from small unilamellar vesicles (SUV) and multilamellar vesicles (MLV) composed of PS. The presence of PC and higher bulk Na+ concentration stabilized the PS vesicles against collapse and total loss of contents, intermediate molecular events in the formation of cochleate structures. From these studies, we conclude that Laurdan fluorescence is a sensitive and a rapid method to detect cochleate phase formation.

  7. The fluorescence microprobe at the LNLS

    Energy Technology Data Exchange (ETDEWEB)

    Radtke, Martin; Perez, Carlos A.; Tolentino, Helio; Vicentin, Flavio C.; Neuenschwander, Regis T.; Barg, Bill [Laboratorio Nacional de Luz Sincrotron (LNLS), Campinas, SP (Brazil); Sanchez, Hector J.; Rubio, Marcelo [Cordoba Univ. Nacional (Argentina). Facultad de Matematica, Astronomia y Fisica; Bueno, Maria Izabel Silveira; Raimundo, Ivo M.; Rohwedder, Jarbas J.R. [Universidade Estadual de Campinas, SP (Brazil). Inst. de Quimica

    1999-11-01

    At the Laboratorio Nacional de Luz Sincrotron (LNLS) the microfocus fluorescence beamline will be operational in the spring of 1998. X-ray fluorescence with synchrotron radiation is an analytical method for determining the concentration of elements at the ppm level. The use of synchrotron radiation instead of conventional X-ray tubes increases the sensitivity of the method substantially. This is due to the higher intensity, the spectral composition, beam focusing and the decrease of background as a result of the polarization of the exciting spectrum. The sample can be excited by the `white` spectrum or monoenergetic beam. The choice of the excitation conditions has a considerable influence on the detection limits. The quantification of the measurements is possible by different mathematical techniques, like Monte Carlo simulation, fundamental parameter programs or, most easily with the calibration by standards if suitable standards are available. The use of focusing capillaries or mirror optics offers the possibility to examine a sample with a spatial resolution of a few {mu}m. One important function is the use of the setup as a scanning microprobe. A two dimensional scan over an unopened fluid inclusion is shown a s example. (author) 10 refs., 7 figs., 1 tab.

  8. Fluorescence-Based Sensors

    Science.gov (United States)

    Orellana, Guillermo

    The natural luminescent phenomena (from the Latin words "lumen" and "essentia", i.e., "made of light") such as northern lights (aurora borealis), marine brightness, glow-worms, shining putrid fish scales, "bluish"- appearing water when contained in certain wooden cups (quinine fluorescence), some stones heated at high temperatures with reducing agents (BaS phosphorescence), or light emitted while crushing sugar (triboluminescence) already fascinated our ancestors. Nowadays we understand that ultraviolet and visible emission of light originates from a competitive deactivation pathway of the lowest electronic excited state of atoms and molecules that produces the so called luminescence (the sub-terms fluorescence and phosphorescence just designate whether the return of the excited to the ground state is an "allowed" or "forbidden" process, namely it is fast or slow, the loosely-defined border between them being a 1-μs-1 rate constant). Actually, luminescence is the only method to generate light in the known Universe regardless it is powered by the nuclear reactions in the stars, the ohmical heating in bulbs, an electric discharge, the absorption of light or a (bio)chemical reaction (chemiluminescence).

  9. The TALE Fluorescence Detectors

    Science.gov (United States)

    Jui, Charles

    2009-05-01

    The TALE fluorescence detectors are designed to extend the threshold for fluorescence observation by TA down to 3x10^16 eV. It will comprise two main components. The first is a set of 24 telescopes working in stereo, with an existing TA FD station at ˜6 km separation. These will cover between 3-31 degrees in elevation and have azimuthal coverage maximizing the stereo aperture in the 10^18-10^19 eV energy range. The second component consists of 15 telescopes equipped with 4m diameter mirrors and covering the sky between 31 and 73 degrees in elevation. The larger mirror size pushes the physics threshold down to 3x10^16 eV, and provides view of the shower maximum for the lower energy events. The Tower detector will cover one quadrant in azimuth and operate in hybrid mode with the TALE infill array to provide redundant composition measurements from both shower maximum information and muon-to-electron ratio.

  10. A fluorescence scanning electron microscope

    Directory of Open Access Journals (Sweden)

    Takaaki Kanemaru

    2010-01-01

    Full Text Available Fluorescence techniques are widely used in biological research to examine molecular localization, while electron microscopy can provide unique ultrastructural information. To date, correlative images from both fluorescence and electron microscopy have been obtained separately using two different instruments, i.e. a fluorescence microscope (FM and an electron microscope (EM. In the current study, a scanning electron microscope (SEM (JEOL JXA8600 M was combined with a fluorescence digital camera microscope unit and this hybrid instrument was named a fluorescence SEM (FL-SEM. In the labeling of FL-SEM samples, both Fluolid, which is an organic EL dye, and Alexa Fluor, were employed. We successfully demonstrated that the FL-SEM is a simple and practical tool for correlative fluorescence and electron microscopy.

  11. Time-Resolved Fluorescence in Lipid Bilayers: Selected Applications and Advantages over Steady State

    Science.gov (United States)

    Amaro, Mariana; Šachl, Radek; Jurkiewicz, Piotr; Coutinho, Ana; Prieto, Manuel; Hof, Martin

    2014-01-01

    Fluorescence methods are versatile tools for obtaining dynamic and topological information about biomembranes because the molecular interactions taking place in lipid membranes frequently occur on the same timescale as fluorescence emission. The fluorescence intensity decay, in particular, is a powerful reporter of the molecular environment of a fluorophore. The fluorescence lifetime can be sensitive to the local polarity, hydration, viscosity, and/or presence of fluorescence quenchers/energy acceptors within several nanometers of the vicinity of a fluorophore. Illustrative examples of how time-resolved fluorescence measurements can provide more valuable and detailed information about a system than the time-integrated (steady-state) approach will be presented in this review: 1), determination of membrane polarity and mobility using time-dependent spectral shifts; 2), identification of submicroscopic domains by fluorescence lifetime imaging microscopy; 3), elucidation of membrane leakage mechanisms from dye self-quenching assays; and 4), evaluation of nanodomain sizes by time-resolved Förster resonance energy transfer measurements. PMID:25517142

  12. Elite Polarization and Public Opinion

    DEFF Research Database (Denmark)

    Robison, Joshua; Mullinix, Kevin

    2016-01-01

    Elite polarization has reshaped American politics and is an increasingly salient aspect of news coverage within the United States. As a consequence, a burgeoning body of research attempts to unravel the effects of elite polarization on the mass public. However, we know very little about how...... polarization is communicated to the public by news media. We report the results of one of the first content analyses to delve into the nature of news coverage of elite polarization. We show that such coverage is predominantly critical of polarization. Moreover, we show that unlike coverage of politics focused...... on individual politicians, coverage of elite polarization principally frames partisan divisions as rooted in the values of the parties rather than strategic concerns. We build on these novel findings with two survey experiments exploring the influence of these features of polarization news coverage on public...

  13. Polarized Emission from Interstellar Dust

    CERN Document Server

    Vaillancourt, J E

    2006-01-01

    Observations of far-infrared (FIR) and submillimeter (SMM) polarized emission are used to study magnetic fields and dust grains in dense regions of the interstellar medium (ISM). These observations place constraints on models of molecular clouds, star-formation, grain alignment mechanisms, and grain size, shape, and composition. The FIR/SMM polarization is strongly dependent on wavelength. We have attributed this wavelength dependence to sampling different grain populations at different temperatures. To date, most observations of polarized emission have been in the densest regions of the ISM. Extending these observations to regions of the diffuse ISM, and to microwave frequencies, will provide additional tests of grain and alignment models. An understanding of polarized microwave emission from dust is key to an accurate measurement of the polarization of the cosmic microwave background. The microwave polarization spectrum will put limits on the contributions to polarized emission from spinning dust and vibrat...

  14. Optimization of polarization lidar structure

    Science.gov (United States)

    Abramochkin, Alexander I.; Kaul, Bruno V.; Tikhomirov, Alexander A.

    1999-11-01

    The problems of the polarization lidar transceiver optimization are considered. The basic features and the optimization criteria of lidar polarization units are presented and the comparative analysis of polarization units is fulfilled. We have analyzed optical arrangements of the transmitter to form the desired polarization state of sounding radiation. We have also considered various types of lidar receiving systems: (1) one-channel, providing measurement of Stocks parameters at a successive change of position of polarization analyzers in the lidar receiver, and (2) multichannel, where each channel has a lens, an analyzer, and a photodetector. In the latter case measurements of Stocks parameters are carried out simultaneously. The optimization criteria of the polarization lidar considering the atmospheric state are determined with the purpose to decrease the number of polarization devices needed.

  15. Fluorescence of ceramic color standards.

    Science.gov (United States)

    Koo, Annette; Clare, John F; Nield, Kathryn M; Deadman, Andrew; Usadi, Eric

    2010-04-20

    Fluorescence has been found in color standards available for use in calibration and verification of color measuring instruments. The fluorescence is excited at wavelengths below about 600?nm and emitted above 700?nm, within the response range of silicon photodiodes, but at the edge of the response of most photomultipliers and outside the range commonly scanned in commercial colorimeters. The degree of fluorescence on two of a set of 12 glossy ceramic tiles is enough to introduce significant error when those tiles have been calibrated in one mode of measurement and are used in another. We report the nature of the fluorescence and the implications for color measurement.

  16. Identification of polarized macrophage subsets in zebrafish.

    Science.gov (United States)

    Nguyen-Chi, Mai; Laplace-Builhe, Béryl; Travnickova, Jana; Luz-Crawford, Patricia; Tejedor, Gautier; Phan, Quang Tien; Duroux-Richard, Isabelle; Levraud, Jean-Pierre; Kissa, Karima; Lutfalla, Georges; Jorgensen, Christian; Djouad, Farida

    2015-07-08

    While the mammalian macrophage phenotypes have been intensively studied in vitro, the dynamic of their phenotypic polarization has never been investigated in live vertebrates. We used the zebrafish as a live model to identify and trail macrophage subtypes. We generated a transgenic line whose macrophages expressing tumour necrosis factor alpha (tnfa), a key feature of classically activated (M1) macrophages, express fluorescent proteins Tg(mpeg1:mCherryF/tnfa:eGFP-F). Using 4D-confocal microscopy, we showed that both aseptic wounding and Escherichia coli inoculation triggered macrophage recruitment, some of which started to express tnfa. RT-qPCR on Fluorescence Activated Cell Sorting (FACS)-sorted tnfa(+) and tnfa(-) macrophages showed that they, respectively, expressed M1 and alternatively activated (M2) mammalian markers. Fate tracing of tnfa(+) macrophages during the time-course of inflammation demonstrated that pro-inflammatory macrophages converted into M2-like phenotype during the resolution step. Our results reveal the diversity and plasticity of zebrafish macrophage subsets and underline the similarities with mammalian macrophages proposing a new system to study macrophage functional dynamic.

  17. Fluorescence dynamics of green fluorescent protein in AOT reversed micelles

    NARCIS (Netherlands)

    Uskova, M.A.; Borst, J.W.; Hink, M.A.; Hoek, van A.; Schots, A.; Klyachko, N.L.; Visser, A.J.W.G.

    2000-01-01

    We have used the enhanced green fluorescent protein (EGFP) to investigate the properties of surfactant-entrapped water pools in organic solvents (reversed micelles) with steady-state and time-resolved fluorescence methods. The surfactant used was sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and the

  18. Polar Cap Retreat

    Science.gov (United States)

    2004-01-01

    13 August 2004 This red wide angle Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a view of the retreating seasonal south polar cap in the most recent spring in late 2003. Bright areas are covered with frost, dark areas are those from which the solid carbon dioxide has sublimed away. The center of this image is located near 76.5oS, 28.2oW. The scene is large; it covers an area about 250 km (155 mi) across. The scene is illuminated by sunlight from the upper left.

  19. Polar Direct Drive

    Science.gov (United States)

    Skupsky, S.

    2003-10-01

    Direct drive offers the potential of higher target gain on the National Ignition Facility (NIF) than x-ray drive: The initial direct-drive target design had a 1-D gain of 45 and consisted primarily of a pure cryogenic DT shell. Using the expected levels of target and laser nonuniformities for the NIF, two-dimensional (2-D) hydrodynamic simulations predicted target gains around 30.(P.W. McKenty et al.), Phys. Plasmas 8, 2315 (2001). More-recent designs have shown that higher target gains could be obtained by replacing a portion of the DT shell with ``wetted'' CH foam and by using adiabat shaping: (1) Higher-Z material (C) in the foam increases laser absorption by about 40% (from 60% absorption to 85%).(S. Skupsky et al.), in Inertial Fusion Sciences and Applications 2001, edited by K. Tanaka et al. (Elsevier, Paris, 2002), p. 240. (2) Adiabat shaping allows the main portion of the fuel to be placed on a lower adiabat without compromising target stability.(V.N. Goncharov et al.), Phys. Plasmas 10, 1906 (2003). These direct-drive concepts can be tested on the NIF, long before that facility is converted to a direct-drive (spherically symmetric) irradiation configuration. Using the NIF x-ray-drive beam configuration, some of the near-polar beams could be pointed to better illuminate the target's equator. These more-oblique, equatorial beams will have lower absorption and reduced drive efficiency than the polar beams. One strategy to compensate for the difference in polar and equatorial drive is to reduce the irradiation at the poles and employ different pulse shapes to accommodate the time-dependent variations in drive and absorption. This concept of polar direct drive (PDD) has been studied using the 2-D hydrocode DRACO to determine the requirements for achieving ignition and moderate target gain for the NIF. Experiments on the OMEGA laser will examine the effects of oblique irradiation on target drive. Results of simulations for different direct-drive target designs

  20. Plasma polarization spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fujimoto, Takashi; Iwamae, Atsushi (eds.) [Kyoto Univ. (Japan). Dept. of Mechanical Engineering and Science

    2008-07-01

    Plasma Polarization Spectroscopy (PPS) is now becoming a standard diagnostic technique for working with laboratory plasmas. This new area needs a comprehensive framework, both experimental and theoretical. This book reviews the historical development of PPS, develops a general theoretical formulation to deal with this phenomenon, along with an overview of relevant cross sections, and reports on laboratory experiments so far performed. It also includes various facets that are interesting from this standpoint, e.g. X-ray lasers and effects of microwave irradiation. It also offers a timely discussion of instrumentation that is quite important in a practical PPS experiment. (orig.)

  1. Circularly polarized antennas

    CERN Document Server

    Gao, Steven; Zhu, Fuguo

    2013-01-01

    This book presents a comprehensive insight into the design techniques for different types of CP antenna elements and arrays In this book, the authors address a broad range of topics on circularly polarized (CP) antennas. Firstly, it introduces to the reader basic principles, design techniques and characteristics of various types of CP antennas, such as CP patch antennas, CP helix antennas, quadrifilar helix antennas (QHA), printed quadrifilar helix antennas (PQHA), spiral antenna, CP slot antennas, CP dielectric resonator antennas, loop antennas, crossed dipoles, monopoles and CP horns. Adva

  2. Influence of polar cap currents on pulsar polarization

    CERN Document Server

    Kumar, D

    2012-01-01

    We have developed a model for the polarization of curvature radiation for pulsars by taking into account the polar cap induced perturbation on the nonrotating (slowly rotating) dipolar magnetic field, where the rotation effects such as aberration and retardation can be ignored. We have simulated a set of typical pulse profiles to understand the role of induced magnetic field on radio emission of pulsars, and found to be significantly influencing the profile structure and polarization. Our model indicates that the intensity components and the polarization angle inflection point can get shifted to either leading or trailing side depending upon the prevailing conditions in the viewing geometry, the non-uniformity in source distribution (modulation) and the polar cap current induced perturbation. Also, we find an evidence for the origin of symmetric type circular polarization in addition to antisymmetric type. Our model predicts for a stronger trailing component compared to that on leading side of a given cone.

  3. New insight in the template decomposition process of large zeolite ZSM-5 crystals: an in situ UV-Vis/fluorescence micro-spectroscopy study

    NARCIS (Netherlands)

    Karwacki, L.; Weckhuysen, B.M.

    2011-01-01

    A combination of in situ UV-Vis and confocal fluorescence micro-spectroscopy was used to study the template decomposition process in large zeolite ZSM-5 crystals. Correlation of polarized light dependent UV-Vis absorption spectra with confocal fluorescence emission spectra in the 400–750 nm region

  4. New insight in the template decomposition process of large zeolite ZSM-5 crystals: an in situ UV-Vis/fluorescence micro-spectroscopy study

    NARCIS (Netherlands)

    Karwacki, L.; Weckhuysen, B.M.

    2011-01-01

    A combination of in situ UV-Vis and confocal fluorescence micro-spectroscopy was used to study the template decomposition process in large zeolite ZSM-5 crystals. Correlation of polarized light dependent UV-Vis absorption spectra with confocal fluorescence emission spectra in the 400–750 nm region a

  5. X-ray instrumentation for analysis of fluorescent and scattered radiation (invited)

    Science.gov (United States)

    Deslattes, Richard D.

    1992-01-01

    Application of high resolution instrumentation to the study of the near-threshold behavior of fluorescent and scattered radiation along with such properties as polarization and angular distribution has proven fertile. This article reviews some alternative strategies for improving the efficiency with which such secondary spectra can be registered.

  6. Excitation-emission fluorescence spectroscopy and time-gated Raman microscopy analysis of dental tissues

    Science.gov (United States)

    Mukhin, M.; Sen, S.; Kouklin, Nikolai A.; Skliarov, A.; Dhuru, D. B.; Iacopino, A. M.; Yakovlev, Vladislav V.

    2007-02-01

    We applied two new spectroscopic techniques (time-gated Raman microscopy and excitation-emission fluorescence microspectroscopy) to characterize healthy and carious dental tissues. These methods were used together with visual inspection, DIAGNOdent, optical polarization microscopy, scanning electron microscopy, and chemical microanalysis to get a more detailed picture of chemical and structural transformations in dental tissues as a result of caries development.

  7. Fluorescence enhancement of warfarin induced by interaction with beta-cyclodextrin.

    Science.gov (United States)

    Vasquez, Jacob M; Vu, Andrew; Schultz, Jerome S; Vullev, Valentine I

    2009-01-01

    Warfarin is the most common agent used for control and prevention of venous as well as arterial thromboembolism (blood clots). In aqueous media, warfarin forms inclusion complexes with a family of cyclic oligosaccharides, alpha, beta, gamma-cyclodextrins (CD). The formation of these complexes results in enhancement of the fluorescence of warfarin. Such spectroscopic changes offer a venue for the development of bioanalytical methodologies for warfarin quantification in biological liquids. We characterized the photophysical properties of warfarin in solvents with varying polarity and viscosity. The fluorescence quantum yield of warfarin correlated: (1) strongly with the solvent viscosity (R = 0.979) and (2) weakly with the solvent polarity (R = 0.118). These findings indicate that it is the change of the viscosity, rather than polarity, of the microenvironment that causes the fluorescence enhancement of warfarin upon binding to beta-CD. Utilizing the observed fluorescence enhancement in fluorescence titration measurements, the binding constants of warfarin to beta-CD were obtained (2.6 x 10(2) M(-1)-3.7 x 10(2) M(-1)). Using multivariable linear analysis, we extracted the stoichiometry of warfarin-beta-CD interaction (1:1).

  8. Assessing Photosynthesis by Fluorescence Imaging

    Science.gov (United States)

    Saura, Pedro; Quiles, Maria Jose

    2011-01-01

    This practical paper describes a novel fluorescence imaging experiment to study the three processes of photochemistry, fluorescence and thermal energy dissipation, which compete during the dissipation of excitation energy in photosynthesis. The technique represents a non-invasive tool for revealing and understanding the spatial heterogeneity in…

  9. X-ray Fluorescence Sectioning

    CERN Document Server

    Cong, Wenxiang

    2012-01-01

    In this paper, we propose an x-ray fluorescence imaging system for elemental analysis. The key idea is what we call "x-ray fluorescence sectioning". Specifically, a slit collimator in front of an x-ray tube is used to shape x-rays into a fan-beam to illuminate a planar section of an object. Then, relevant elements such as gold nanoparticles on the fan-beam plane are excited to generate x-ray fluorescence signals. One or more 2D spectral detectors are placed to face the fan-beam plane and directly measure x-ray fluorescence data. Detector elements are so collimated that each element only sees a unique area element on the fan-beam plane and records the x-ray fluorescence signal accordingly. The measured 2D x-ray fluorescence data can be refined in reference to the attenuation characteristics of the object and the divergence of the beam for accurate elemental mapping. This x-ray fluorescence sectioning system promises fast fluorescence tomographic imaging without a complex inverse procedure. The design can be ad...

  10. Imaging of polarity during zygotic and somatic embryogenesis of carrot (Daucus carota L.).

    NARCIS (Netherlands)

    Timmers, A.C.J.

    1993-01-01

    In this thesis a study of the regulation of coordinated growth and the development of polarity during embryogenesis of carrot, Daucus carota L., is described. To this end, several microscopical techniques were used, such as light microscopy, fluorescence microscopy, confocal scanning laser microscop

  11. Polarization and Polarimetry: A Review

    CERN Document Server

    Trippe, S

    2014-01-01

    Polarization is a basic property of light and is fundamentally linked to the internal geometry of a source of radiation. Polarimetry complements photometric, spectroscopic, and imaging analyses of sources of radiation and has made possible multiple astrophysical discoveries. In this article I review (i) the physical basics of polarization: electromagnetic waves, photons, and parameterizations; (ii) astrophysical sources of polarization: scattering, synchrotron radiation, active media, and the Zeeman, Goldreich-Kylafis, and Hanle effects, as well as interactions between polarization and matter (like birefringence, Faraday rotation, or the Chandrasekhar-Fermi effect); (iii) observational methodology: on-sky geometry, influence of atmosphere and instrumental polarization, polarization statistics, and observational techniques for radio, optical, and X/gamma wavelengths; and (iv) science cases for astronomical polarimetry: solar and stellar physics, planetary system bodies, interstellar matter, astrobiology, astro...

  12. Polarized proton collider at RHIC

    Science.gov (United States)

    Alekseev, I.; Allgower, C.; Bai, M.; Batygin, Y.; Bozano, L.; Brown, K.; Bunce, G.; Cameron, P.; Courant, E.; Erin, S.; Escallier, J.; Fischer, W.; Gupta, R.; Hatanaka, K.; Huang, H.; Imai, K.; Ishihara, M.; Jain, A.; Lehrach, A.; Kanavets, V.; Katayama, T.; Kawaguchi, T.; Kelly, E.; Kurita, K.; Lee, S. Y.; Luccio, A.; MacKay, W. W.; Mahler, G.; Makdisi, Y.; Mariam, F.; McGahern, W.; Morgan, G.; Muratore, J.; Okamura, M.; Peggs, S.; Pilat, F.; Ptitsin, V.; Ratner, L.; Roser, T.; Saito, N.; Satoh, H.; Shatunov, Y.; Spinka, H.; Syphers, M.; Tepikian, S.; Tominaka, T.; Tsoupas, N.; Underwood, D.; Vasiliev, A.; Wanderer, P.; Willen, E.; Wu, H.; Yokosawa, A.; Zelenski, A. N.

    2003-03-01

    In addition to heavy ion collisions (RHIC Design Manual, Brookhaven National Laboratory), RHIC will also collide intense beams of polarized protons (I. Alekseev, et al., Design Manual Polarized Proton Collider at RHIC, Brookhaven National Laboratory, 1998 [2]), reaching transverse energies where the protons scatter as beams of polarized quarks and gluons. The study of high energy polarized protons beams has been a long term part of the program at BNL with the development of polarized beams in the Booster and AGS rings for fixed target experiments. We have extended this capability to the RHIC machine. In this paper we describe the design and methods for achieving collisions of both longitudinal and transverse polarized protons in RHIC at energies up to s=500 GeV.

  13. Formation of polar ring galaxies

    CERN Document Server

    Bournaud, F

    2003-01-01

    Polar ring galaxies are peculiar systems in which a gas rich, nearly polar ring surrounds an early-type or elliptical host galaxy. Two formation scenarios for these objects have been proposed: they are thought to form either in major galaxy mergers or by tidal accretion of the polar material from a gas rich donor galaxy. Both scenarios are studied through N-body simulations including gas dynamics and star formation. Constraints on physical parameters are drawn out, in order to determine which scenario is the most likely to occur. Polar ring galaxies from each scenario are compared with observations and we discuss whether the accretion scenario and the merging scenario account for observational properties of polar ring galaxies. The conclusion of this study is that the accretion scenario is both the most likely and the most supported by observations. Even if the merging scenario is rather robust, most polar ring galaxies are shown to be the result of tidal gas accretion events.

  14. Optical Properties of Fluorescent Dyes

    Institute of Scientific and Technical Information of China (English)

    李戎; 陈东辉

    2001-01-01

    Fluorescent dyes have been widely used these years.Because of the special optical performance, conventional CCM systems seem to be unable to predict the recipes of fabrics dyed with fluorescent dyes. In order to enhance the functions of CCM systems, the optical properties of fluorescent dyes in their absorption region were investigated. It has been found that there was a fixed maximum absorption wavelength for each fluorescent dyes whatever its concentration is. Both absorption region and maximum absorption wavelength of the dyes in solution are the same to those in fabric, and that the absorption is directly proportional to the concentration of the dye. So the optical properties obtained in solutions cna be applied for describing the optics performance of fluorescent dyes in fabrics.

  15. O2(1△) Yield Measurement by Raman Spectroscopy With Elimination of Chlorine Fluorescence Interference

    Institute of Scientific and Technical Information of China (English)

    Rong-rong Cui; Wen-bo Shi; Lie-zheng Deng; He-ping Yang; Guo-he Sha; Cun-hao Zhang

    2012-01-01

    Deleterious chlorine fluorescence was found to occur at the same frequency as the Raman scattering of O2(1△) and O2(3∑),seriously affecting the O2(1△) yield measurement in the reaction of chlorine with basic hydrogen peroxide by use of the Raman spectroscopy technique.To solve this problem we have taken advantage of the fact that Raman radiation is always strongly polarized while fluorescence is essentially non-polarized in a gaseous medium.When chlorine utilization of a singlet oxygen generator is 88%,O2(1△) yield reaches (42.4±7.4)%with the effect of chlorine fluorescence completely eliminated.

  16. Detecting cervical cancer progression through extracted intrinsic fluorescence and principal component analysis

    Science.gov (United States)

    Devi, Seema; Panigrahi, Prasanta K.; Pradhan, Asima

    2014-12-01

    Intrinsic fluorescence spectra of the human normal, cervical intraepithelial neoplasia 1 (CIN1), CIN2, and cervical cancer tissue have been extracted by effectively combining the measured polarized fluorescence and polarized elastic scattering spectra. The efficacy of principal component analysis (PCA) to disentangle the collective behavior from smaller correlated clusters in a dimensionally reduced space in conjunction with the intrinsic fluorescence is examined. This combination unambiguously reveals the biochemical changes occurring with the progression of the disease. The differing activities of the dominant fluorophores, collagen, nicotinamide adenine dinucleotide, flavins, and porphyrin of different grades of precancers are clearly identified through a careful examination of the sectorial behavior of the dominant eigenvectors of PCA. To further classify the different grades, the Mahalanobis distance has been calculated using the scores of selected principal components.

  17. Tomographic imaging with polarized light.

    Science.gov (United States)

    Soloviev, Vadim Y; Zacharakis, Giannis; Spiliopoulos, George; Favicchio, Rosy; Correia, Teresa; Arridge, Simon R; Ripoll, Jorge

    2012-06-01

    We report three-dimensional tomographic reconstruction of optical parameters for the mesoscopic light scattering regime from experimentally obtained datasets by using polarized light. We present a numerically inexpensive approximation to the radiative transfer equation governing the polarized light transport. This approximation is employed in the reconstruction algorithm, which computes two optical parameters by using parallel and perpendicular polarizations of transmitted light. Datasets were obtained by imaging a scattering phantom embedding highly absorbing inclusions. Reconstruction results are presented and discussed.

  18. Polarized Electrons for Linear Colliders

    CERN Document Server

    Clendenin, J E; Garwin, E L; Kirby, R E; Luh, D A; Maruyama, T; Prescott, C Y; Sheppard, J C; Turner, J; Prepost, R

    2005-01-01

    Future electron-positron linear colliders require a highly polarized electron beam with a pulse structure that depends primarily on whether the acceleration utilizes warm or superconducting rf structures. The International Linear Collider (ILC) will use cold structures for the main linac. It is shown that a dc-biased polarized photoelectron source such as successfully used for the SLC can meet the charge requirements for the ILC micropulse with a polarization approaching 90%.

  19. Cell Polarity Signaling in Arabidopsis

    OpenAIRE

    Yang, Zhenbiao

    2008-01-01

    Cell polarization is intimately linked to plant development, growth, and responses to the environment. Major advances have been made in our understanding of the signaling pathways and networks that regulate cell polarity in plants owing to recent studies on several model systems, e.g., tip growth in pollen tubes, cell morphogenesis in the leaf epidermis, and polar localization of PINs. From these studies we have learned that plant cells use conserved mechanisms such as Rho family GTPases to i...

  20. Fluorescence calibration method for single-particle aerosol fluorescence instruments

    Science.gov (United States)

    Shipley Robinson, Ellis; Gao, Ru-Shan; Schwarz, Joshua P.; Fahey, David W.; Perring, Anne E.

    2017-05-01

    Real-time, single-particle fluorescence instruments used to detect atmospheric bioaerosol particles are increasingly common, yet no standard fluorescence calibration method exists for this technique. This gap limits the utility of these instruments as quantitative tools and complicates comparisons between different measurement campaigns. To address this need, we have developed a method to produce size-selected particles with a known mass of fluorophore, which we use to calibrate the fluorescence detection of a Wideband Integrated Bioaerosol Sensor (WIBS-4A). We use mixed tryptophan-ammonium sulfate particles to calibrate one detector (FL1; excitation = 280 nm, emission = 310-400 nm) and pure quinine particles to calibrate the other (FL2; excitation = 280 nm, emission = 420-650 nm). The relationship between fluorescence and mass for the mixed tryptophan-ammonium sulfate particles is linear, while that for the pure quinine particles is nonlinear, likely indicating that not all of the quinine mass contributes to the observed fluorescence. Nonetheless, both materials produce a repeatable response between observed fluorescence and particle mass. This procedure allows users to set the detector gains to achieve a known absolute response, calculate the limits of detection for a given instrument, improve the repeatability of the instrumental setup, and facilitate intercomparisons between different instruments. We recommend calibration of single-particle fluorescence instruments using these methods.

  1. Interplay between excited-state intramolecular proton transfer and charge transfer in flavonols and their use as protein-binding-site fluorescence probes

    Energy Technology Data Exchange (ETDEWEB)

    Sytnik, A.; Gormin, D.; Kasha, M. (Florida State Univ., Tallahassee, FL (United States))

    1994-12-06

    A comparative study is presented of competitive fluorescences of three flavonols, 3-hydroxyflavone, 3,3[prime],4[prime],7-tetrahydroxyflavone (fisetin), and 4[prime]-diethylamino-3-hydroxyflavone (DHF). The normal fluorescence S[sub 1] [yields] S[sub 0] (400-nm region) is largely replaced by the proton-transfer tautomer fluorescence S[prime][sub 1] [yields] S[prime][sub 0] in the 550-nm region for all three of the flavonols in aprotic solvents at room temperature. For DHF in polar solvents the normal fluorescence becomes a charge-transfer fluorescence (460-500 nm) which competes strongly with the still dominant proton-transfer fluorescence (at 570 nm). In protic solvents, and at 77 K, the interference with intramolecular hydrogen bonding gives rise to greatly enhanced normal fluorescence, lowering the quantum yield of proton-transfer fluorescence. The utility of DHF as a discriminating fluorescence probe for protein binding sites is suggested by the strong dependence of the charge-transfer fluorescence on polarity of the environment and by various static and dynamic parameters of the charge-transfer and proton-transfer fluorescence which can be determined. 49 refs., 6 figs., 1 tab.

  2. Majorization of quantum polarization distributions

    CERN Document Server

    Luis, Alfredo

    2016-01-01

    Majorization provides a rather powerful partial-order classification of probability distributions depending only on the spread of the statistics, and not on the actual numerical values of the variable being described. We propose to apply majorization as a meta-measure of quantum polarization fluctuations, this is to say of the degree of polarization. We compare the polarization fluctuations of the most relevant classes of quantum and classical-like states. In particular we test the Lieb's conjecture regarding classical-like states as the most polarized and a complementary conjecture that the most unpolarized pure states are the most nonclassical.

  3. Polarization signals in mantis shrimps

    Science.gov (United States)

    Cronin, Thomas W.; Chiou, Tsyr-Huei; Caldwell, Roy L.; Roberts, Nicholas; Marshall, Justin

    2009-08-01

    While color signals are well known as a form of animal communication, a number of animals communicate using signals based on patterns of polarized light reflected from specialized body parts or structures. Mantis shrimps, a group of marine crustaceans, have evolved a great diversity of such signals, several of which are based on photonic structures. These include resonant scattering devices, structures based on layered dichroic molecules, and structures that use birefringent layers to produce circular polarization. Such biological polarizers operate in different spectral regions ranging from the near-UV to medium wavelengths of visible light. In addition to the structures that are specialized for signal production, the eyes of many species of mantis shrimp are adapted to detect linearly polarized light in the ultraviolet and in the green, using specialized sets of photoreceptors with oriented, dichroic visual pigments. Finally, a few mantis shrimp species produce biophotonic retarders within their photoreceptors that permit the detection of circularly polarized light and are thus the only animals known to sense this form of polarization. Mantis shrimps use polarized light in species-specific signals related to mating and territorial defense, and their means of manipulating light's polarization can inspire designs for artificial polarizers and achromatic retarders.

  4. Magnet polarities in the LHC

    CERN Document Server

    McAteer, M; Maclean, E; Persson, T; Steinhagen, R; Tomas, R

    2014-01-01

    We report the results of extensive tests to verify the polarities of Landau damping octupoles (MOF, MOD) and octupole spool correctors (MCO), arc trim skew sextupoles (MSS), and triplet sextupole correctors (MCSX and MCSSX). All octupole circuits that were measured were found to have the expected polarity. All arc skew sextupoles MSS and triplet sextupole correctors MCSX and MCSSX that were measured were found to have reversed polarity with respect to MADX. It is also noted that the triplet quadrupole trims ktqx2, as well as MQS and MQSX, have reversed polarity with respect to MADX.

  5. The RHIC polarized source upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Zelenski, A.; Atoian, G.; Davydenko, V.; Ivanov, A.; Kolmogorov, A.; Ritter, J.; Steski, D.; Zubets, V.

    2010-09-27

    The RHIC polarized H{sup -} ion source is being upgraded to higher intensity (5-10 mA) and polarization for use in the RHIC polarization physics program at enhanced luminosity RHIC operation. The higher beam peak intensity will allow reduction of the transverse beam emittance at injection to AGS to reduce polarization losses in AGS. There is also a planned RHIC luminosity upgrade by using the electron beam lens to compensate the beam-beam interaction at collision points. This upgrade is also essential for future BNL plans for a high-luminosity electron - proton (ion) Collider eRHIC.

  6. Polarization-preserving holey fibers

    DEFF Research Database (Denmark)

    Broeng, Jes; Mogilevtsev, Dmitri; Libori, Stig E. Barkou

    2001-01-01

    In this work we suggest and discuss a microstructure of air capillaries with elliptical cross-section in a tread of glass that gives opportunity for Creation of polarization-preserving fiber with very small beat length between the fundamental modes of different polarization......In this work we suggest and discuss a microstructure of air capillaries with elliptical cross-section in a tread of glass that gives opportunity for Creation of polarization-preserving fiber with very small beat length between the fundamental modes of different polarization...

  7. Antiproton beam polarizer using a dense polarized target

    Energy Technology Data Exchange (ETDEWEB)

    Wojtsekhowski, Bogdan

    2011-05-01

    We describe considerations regarding the spin filtering method for the antiproton beam. The proposed investigation of the double polarization cross section for antiproton to nucleon interaction is outlined. It will use a single path of the antiproton beam through a dense polarized target, e.g. 3He or CH2, followed by a polarimeter.

  8. Weak Polarized Electron Scattering

    CERN Document Server

    Erler, Jens; Mantry, Sonny; Souder, Paul A

    2014-01-01

    Scattering polarized electrons provides an important probe of the weak interactions. Precisely measuring the parity-violating left-right cross section asymmetry is the goal of a number of experiments recently completed or in progress. The experiments are challenging, since A_{LR} is small, typically between 10^(-4) and 10^(-8). By carefully choosing appropriate targets and kinematics, various pieces of the weak Lagrangian can be isolated, providing a search for physics beyond the Standard Model. For other choices, unique features of the strong interaction are studied, including the radius of the neutron density in heavy nuclei, charge symmetry violation, and higher twist terms. This article reviews the theory behind the experiments, as well as the general techniques used in the experimental program.

  9. Interferometric polarization control

    Science.gov (United States)

    Wollack, Edward J. (Inventor); Moseley, Samuel H. (Inventor); Novak, Giles A. (Inventor); Chuss, David T. (Inventor)

    2009-01-01

    A signal conditioning module provides a polarimeter capability in a photometric system. The module may include multiple variable delay polarization modulators. Each modulator may include an input port, and a first arm formed to include a first reflector and first rooftop mirror arranged in opposed relationship. The first reflector may direct an input radiation signal to the first rooftop mirror. Each modulator also may include an output port and a second arm formed to include a second reflector and second rooftop mirror arranged in opposed relationship. The second reflector can guide a signal from the second rooftop mirror towards the output port to provide an output radiation signal. A beamsplitting grid may be placed between the first reflector and the first rooftop mirror, and also between the second reflector and the second rooftop mirror. A translation apparatus can provide adjustment relative to optical path length vis-a-vis the first arm, the second arm and the grid.

  10. Single Molecule Spectroscopy of Fluorescent Proteins

    NARCIS (Netherlands)

    Blum, Christian; Subramaniam, Vinod

    2009-01-01

    The discovery and use of fluorescent proteins has revolutionized cellular biology. Despite the widespread use of visible fluorescent proteins as reporters and sensors in cellular environments the versatile photophysics of fluorescent proteins is still subject to intense research. Understanding the

  11. Synthesis and spectral characterization of a new blue fluorescent tripod for detecting metal cations and protons

    Energy Technology Data Exchange (ETDEWEB)

    Staneva, Desislava [University of Chemical Technology and Metallurgy, 1756 Sofia (Bulgaria); Makki, Mohammad S.I.; Sobahi, Tariq R. [Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Bosch, Paula [Institute of Science and Technology of Polymers, CSIC, Juan de la Cierva 3, 28006, Madrid (Spain); Abdel-Rahman, Reda M. [Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Asiri, Abdullah [Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Center of Excellence for Advanced Materials Research (CEAMR), King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Grabchev, Ivo, E-mail: i.grabchev@chem.uni-sofia.bg [Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Sofia University “St. Kliment Ohridski”, Faculty of Medicine, 1407 Sofia (Bulgaria)

    2015-06-15

    A new symmetrical blue fluorescent tripod containing three 1,8-naphtalimide fragments has been synthesized. Its spectral properties have been investigated in organic solvents of different polarity. Its basic photophysical characteristics depend strongly on the polarity of the organic solvents. In nonpolar solvents (diethyl ether, chloroform and toluene) the new tripod emits eximer fluorescence. The new tripod has been investigated as a ligand for detection of metal ions (Ag{sup +}, Co{sup 2+}, Pb{sup 2+}, Zn{sup 2+}, Ni{sup 2+}, and Cu{sup 2+}) in acetonitrile and acetonitrile/H{sub 2}O (1:4, v/v). The influence of protons in an ethanol–water (1:4, v/v) solution and in toluene and diethyl ether solvents on the tripod fluorescence intensity has been investigated and it has been shown that the protons destroy the excimer formations recovering the monomer fluorescence. - Highlights: • New blue fluorescent tripod containing three 1,8-naphtalimide fragments was described. • In nonpolar solvents the new tripod emits eximer fluorescence. • The new tripod has been investigated as a ligand for metal ions and protons.

  12. Circularly Polarized MHOHG with Bichromatic Circularly Polarized Laser Pulses

    Science.gov (United States)

    Bandrauk, Andre D.; Mauger, Francois; Uzer, Turgay

    2016-05-01

    Circularly polarized MHOHG-Molecular High Order Harmonic Generation is shown to occur efficiently with intense ultrashort bichromatic circularly polarized pulses due to frequent electron-parent -ion recollision with co-or counter-rotating incident circular pulses as predicted in 1995. We show in this context that molecules offer a very robust and efficient frameworkfor the production of circularly polarized harmonics for the generation of single circularly polarized ``attosecond'' pulses. The efficiency of such new MHOHG is shown to depend on the compatibility of the symmetry of the molecular medium with the net electric field generated by the combination of the laser pulses.Using a time-dependent symmetry analysis with concrete examples such as H 2 + vs H 3 + we show how all the features(harmonic order and ∧ polarization) of MHOHG can be explained and predicted.

  13. FLEX: fluorescence explorer

    Science.gov (United States)

    Stoll, Marc-Ph.; Court, Andrew; Smorenburg, Kees; Visser, Huib; Crocco, Luiggi; Heilimo, Jyro; Honig, Andre

    1999-12-01

    FLEX is a scientifically driven space mission to provide demonstration/validation of the instrumentation and technique for measuring the natural fluorescence of vegetation in the Fraunhofer lines. The payload consists of high spectral resolution (0.1 - 0.3 nm) CCD imaging grating spectrometer with two channels: one in the red (648 - 664 nm) and one in the blue (391 - 438 nm) for working with several Fraunhofer lines. The across track FOV is 8.4 degrees; ground spatial resolution is better than 0.5 X 0.5 km2. To increase the S/N ratio a steering mirror will be used, if necessary, to 'freeze' the image and also to provide plus or minus 4 degrees across track depointing. Calibration is made by viewing the sun via a diffuser plate switched into the telescope field of view. A separate CCD camera will allow cloud detection and scene identification. A TIR radiometer will provide simultaneous surface temperature measurements. The spacecraft, overall mass estimated at 200 kg, is derived from the ASI-MITA bus which provides all the necessary subsystems and stabilized platform. By use of on-board storage, ground requirements for satellite control and data link are minimized; the possibility of local stations for real time reception/distribution is also envisaged. Provisional orbit characteristics are: LEO sun synchronous, 500 - 900 km altitude. Priority will be given to highest revisit frequency on a sufficient number of selected test sites.

  14. Fluorescent blood cell angiography

    Science.gov (United States)

    Ben-nun, Joshua; Constable, Ian J.

    1994-06-01

    Fluorescein angiography is currently the main method for evaluation of the retinal vascular patency. Ashton noted that capillary patency to the small fluorescein molecule may differ from that of the larger red blood cells. He concluded that fluorescein angiography is not able to demonstrate a developing stenosis, that might be the precipitating cause of a later capillary closure in various microvasculopathies. Sarelius et al have shown, in hamster cheek pouch and cremaster muscle, that fluorescently labeled erythrocytes in known concentrations can be used for the direct measurement of capillary flow parameters. The only assumption that this method relies on, is that the labeled cells are rheologically normal and therefore reflect the behavior of the total cell population. We have developed a new method for an in-vivo, real-time demonstration of the blood cell flow in the retinal capillary net. Based on the assumption presented by Sarelius et al, measurement and analysis of the retinal capillary blood cell flow is also possible from the results achieved by the new method.

  15. Fluorescence endoscopy and photodynamic therapy.

    Science.gov (United States)

    Messmann, H; Endlicher, E; Gelbmann, C M; Schölmerich, J

    2002-10-01

    Fluorescence endoscopy is a new technique which allows a better detection of non-visible malignant or premalignant lesions or, those which are difficult to detect. Exogenously applied sensitisers accumulate selectively in malignant lesions and induce fluorescence after illumination with light of adequate wavelength. However, also endogenous fluorophores, different located in malignant or benign lesions, induce a different autofluorescence in these lesions. Tissue fluorescence can be detected by optical sampling of the mucosa using fluorescence spectroscopy or by generating real time fluorescence images with specialised camera systems. Compared to point fluorescence spectroscopy the latter technique enables the screening of large surface areas of mucosa. Meanwhile, fluorescence endoscopy is a widely used technique in urology employing 5-aminolaevulinic acid sensitisation. In gastroenterology, this technique seems promising for the detection of early cancers or dysplasia in patients with Barrett's oesophagus or ulcerative colitis. Using different sensitisers, photodynamic therapy seems to be a promising option for patients with advanced oesophageal cancer and in the palliative treatment of non-resectable bile duct cancer, furthermore for patients with early gastric cancer and dysplasia in Barrett's oesophagus. Probably, by laser light fractionation or a combination of different sensitisers, an enhanced effect can be expected.

  16. Resonant soft X-ray fluorescence spectra of molecules

    Energy Technology Data Exchange (ETDEWEB)

    Nordgren, J.; Glans, P.; Gunnelin, K.; Guo, J.; Skytt, P.; Saathe, C.; Wassdahl, N. [Uppsala Univ. (Sweden). Dept. of Phys.

    1997-08-01

    A review is presented of some recent advancements in resonant soft X-ray fluorescence spectroscopy applied to molecules. The concept of inelastic scattering is discussed for molecules with an element of symmetry, which introduces degeneracy or near-degeneracy of core excited states. The potential of the symmetry selection rules associated with resonant X-ray fluorescence is illustrated in studies of electronic structure as well as molecular dynamics. The use of polarized photons for exciting X-ray emission is discussed, and examples are presented where anisotropy of X-ray emission provides more detailed information. A brief section discusses the experimental considerations relevant for the spectroscopic technique. (orig.) With 013 figs., 28 refs.

  17. Time-resolved fluorescence analysis of the mobile flavin cofactor in -hydroxybenzoate hydroxylase

    Indian Academy of Sciences (India)

    Petra A W Van Den Berg; Koert Grever; Arie Van Hoek; Willem J H Van Berkel; Antonie J W G Visser

    2007-03-01

    Conformational heterogeneity of the FAD cofactor in -hydroxybenzoate hydroxylase (PHBH) was investigated with time-resolved polarized flavin fluorescence. For binary enzyme/substrate (analogue) complexes of wild-type PHBH and Tyr222 mutants, crystallographic studies have revealed two distinct flavin conformations; the `in’ conformation with the isoalloxazine ring located in the active site, and the `out’ conformation with the isoalloxazine ring disposed towards the protein surface. Fluorescence-lifetime analysis of these complexes revealed similar lifetime distributions for the `in’ and `out’ conformations. The reason for this is twofold. First, the active site of PHBH contains various potential fluorescence-quenching sites close to the flavin. Fluorescence analysis of uncomplexed PHBH Y222V and Y222A showed that Tyr222 is responsible for picosecond fluorescence quenching free enzyme. In addition, other potential quenching sites, including a tryptophan and two tyrosines involved in substrate binding, are located nearby. Since the shortest distance between these quenching sites and the isoalloxazine ring differs only little on average, these aromatic residues are likely to contribute to fluorescence quenching. Second, the effect of flavin conformation on the fluorescence lifetime distribution is blurred by binding of the aromatic substrates: saturation with aromatic substrates induces highly efficient fluorescence quenching. The flavin conformation is therefore only reflected in the small relative contributions of the longer lifetimes.

  18. Studies of the laser-induced fluorescence of explosives and explosive compositions.

    Energy Technology Data Exchange (ETDEWEB)

    Hargis, Philip Joseph, Jr. (,; .); Thorne, Lawrence R.; Phifer, Carol Celeste; Parmeter, John Ethan; Schmitt, Randal L.

    2006-10-01

    Continuing use of explosives by terrorists throughout the world has led to great interest in explosives detection technology, especially in technologies that have potential for standoff detection. This LDRD was undertaken in order to investigate the possible detection of explosive particulates at safe standoff distances in an attempt to identify vehicles that might contain large vehicle bombs (LVBs). The explosives investigated have included the common homogeneous or molecular explosives, 2,4,6-trinitrotoluene (TNT), pentaerythritol tetranitrate (PETN), cyclonite or hexogen (RDX), octogen (HMX), and the heterogeneous explosive, ammonium nitrate/fuel oil (ANFO), and its components. We have investigated standard excited/dispersed fluorescence, laser-excited prompt and delayed dispersed fluorescence using excitation wavelengths of 266 and 355 nm, the effects of polarization of the laser excitation light, and fluorescence imaging microscopy using 365- and 470-nm excitation. The four nitro-based, homogeneous explosives (TNT, PETN, RDX, and HMX) exhibit virtually no native fluorescence, but do exhibit quenching effects of varying magnitude when adsorbed on fluorescing surfaces. Ammonium nitrate and fuel oil mixtures fluoresce primarily due to the fuel oil, and, in some cases, due to the presence of hydrophobic coatings on ammonium nitrate prill or impurities in the ammonium nitrate itself. Pure ammonium nitrate shows no detectable fluorescence. These results are of scientific interest, but they provide little hope for the use of UV-excited fluorescence as a technique to perform safe standoff detection of adsorbed explosive particulates under real-world conditions with a useful degree of reliability.

  19. Deriving binary phase diagrams for chromonic materials in water mixtures via fluorescence spectroscopy: cromolyn and water.

    Science.gov (United States)

    Van Hecke, Gerald R; Karukstis, Kerry K; Rayermann, Scott

    2015-01-14

    We report here the first example of a new and novel method of determining the binary temperature-composition phase diagram of a chromonic material in water using its intrinsic fluorescence. Disodium cromoglycate, or cromolyn, is an anti-allergy medicine representative of a class of compounds known as the chromonics. We have discovered that cromolyn's fluorescence is very sensitive to the polarity, hence structure, of the phase it exhibits. The fluorescence signal shifts its wavelength maximum and its shape depending on whether the cromolyn is a single phase or in coexisting phases. Since the signal due to individual phases can be identified, the fluorescence signal can reveal the temperature-induced transitions between single phase and phase coexistence regions. By studying such fluorescence data for different compositions, an isobaric temperature-composition phase diagram may be constructed. We present here a phase diagram derived from fluorescence studies that is in agreement with previous determinations using other techniques. Our results suggest that the binary phase diagrams of other intrinsically fluorescent chromonic materials, such as perylene monoimide and bisimide derivatives used in organic optoelectronic devices, solar cells, and light-emitting diodes, can be studied in water using an analogous fluorescence approach.

  20. Research on polarization imaging information parsing method

    Science.gov (United States)

    Yuan, Hongwu; Zhou, Pucheng; Wang, Xiaolong

    2016-11-01

    Polarization information parsing plays an important role in polarization imaging detection. This paper focus on the polarization information parsing method: Firstly, the general process of polarization information parsing is given, mainly including polarization image preprocessing, multiple polarization parameters calculation, polarization image fusion and polarization image tracking, etc.; And then the research achievements of the polarization information parsing method are presented, in terms of polarization image preprocessing, the polarization image registration method based on the maximum mutual information is designed. The experiment shows that this method can improve the precision of registration and be satisfied the need of polarization information parsing; In terms of multiple polarization parameters calculation, based on the omnidirectional polarization inversion model is built, a variety of polarization parameter images are obtained and the precision of inversion is to be improve obviously; In terms of polarization image fusion , using fuzzy integral and sparse representation, the multiple polarization parameters adaptive optimal fusion method is given, and the targets detection in complex scene is completed by using the clustering image segmentation algorithm based on fractal characters; In polarization image tracking, the average displacement polarization image characteristics of auxiliary particle filtering fusion tracking algorithm is put forward to achieve the smooth tracking of moving targets. Finally, the polarization information parsing method is applied to the polarization imaging detection of typical targets such as the camouflage target, the fog and latent fingerprints.

  1. Direct probing of chromatography columns by laser-induced fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    McGuffin, V.L.

    1992-12-07

    This report summarizes the progress and accomplishments of this research project from September 1, 1989 to February 28, 1993. During this period, we have accomplished all of the primary scientific objectives of the research proposal: (1) constructed and evaluated a laser-induced fluorescence detection system that allows direct examination of the chromatographic column, (2) examined nonequilibrium processes that occur upon solute injection and elution, (3) examined solute retention in liquid chromatography as a function of temperature and pressure, (4) examined solute zone dispersion in liquid chromatography as a function of temperature and pressure, and (5) developed appropriate theoretical models to describe these phenomena. In each of these studies, substantial knowledge has been gained of the fundamental processes that are responsible for chromatographic separations. In addition to these primary research objectives, we have made significant progress in three related areas: (1) examined pyrene as a fluorescent polarity probe insupercritical fluids and liquids as a function of temperature and pressure, (2) developed methods for the class-selective identification of polynuclear aromatic hydrocarbons in coal-derived fluids by microcolumn liquid chromatography with fluorescence quenching detection, and (3) developed methods for the determination of saturated and unsaturated (including omega-3) fatty acids in fish oil extracts by microcolumn liquid chromatography with laser-induced fluorescence detection. In these studies, the advanced separation and detection techniques developed in our laboratory are applied to practical problems of environmental and biomedical significance.

  2. Direct probing of chromatography columns by laser-induced fluorescence

    Science.gov (United States)

    McGuffin, V. L.

    1992-12-01

    This report summarizes the progress and accomplishments of this research project from 1 Sep. 1989 to 28 Feb. 1993. During this period, we have accomplished all of the primary scientific objectives of the research proposal: (1) constructed and evaluated a laser-induced fluorescence detection system that allows direct examination of the chromatographic column, (2) examined nonequilibrium processes that occur upon solute injection and elution, (3) examined solute retention in liquid chromatography as a function of temperature and pressure, (4) examined solute zone dispersion in liquid chromatography as a function of temperature and pressure, and (5) developed appropriate theoretical models to describe these phenomena. In each of these studies, substantial knowledge has been gained of the fundamental processes that are responsible for chromatographic separations. In addition to these primary research objectives, we have made significant progress in three related areas: (1) examined pyrene as a fluorescent polarity probe in supercritical fluids and liquids as a function of temperature and pressure, (2) developed methods for the class-selective identification of polynuclear aromatic hydrocarbons in coal-derived fluids by microcolumn liquid chromatography with fluorescence quenching detection, and (3) developed methods for the determination of saturated and unsaturated (including omega-3) fatty acids in fish oil extracts by microcolumn liquid chromatography with laser-induced fluorescence detection. In these studies, the advanced separation and detection techniques developed in our laboratory are applied to practical problems of environmental and biomedical significance.

  3. Online observation of emulsion polymerization by fluorescence technique

    CERN Document Server

    Rudschuck, S; Fuhrmann, J

    1999-01-01

    An online observation of local polarity via fluorescence spectroscopy was used to study the formation and growth of polymer particles during an emulsifier-free heterogeneous polymerization. The reaction mixture consisted of styrene dispersed in water and the polymerization was initiated by a macro-initiator (hydrolyzed propene-maleic acid copolymer with t-butyl perester groups). Pyrenyl probes were attached to the backbone of the initiator to analyze the heterogeneous reaction. The experimental results allow a clear distinction of different time regions during the heterogeneous polymerization. Information about the heating period, the latex formation, the particle growth and the final stage of the polymerization process (gel point) were obtained. (11 refs).

  4. Polarization Imaging and Insect Vision

    Science.gov (United States)

    Green, Adam S.; Ohmann, Paul R.; Leininger, Nick E.; Kavanaugh, James A.

    2010-01-01

    For several years we have included discussions about insect vision in the optics units of our introductory physics courses. This topic is a natural extension of demonstrations involving Brewster's reflection and Rayleigh scattering of polarized light because many insects heavily rely on optical polarization for navigation and communication.…

  5. Create a Polarized Light Show.

    Science.gov (United States)

    Conrad, William H.

    1992-01-01

    Presents a lesson that introduces students to polarized light using a problem-solving approach. After illustrating the concept using a slinky and poster board with a vertical slot, students solve the problem of creating a polarized light show using Polya's problem-solving methods. (MDH)

  6. Polarization effect in parametric amplifier

    Institute of Scientific and Technical Information of China (English)

    Junhe Zhou; Jianping Chen; Xinwan Li; Guiling Wu; Yiping Wang

    2005-01-01

    @@ Polarization effect in parametric amplifiers is studied. Coupled equations are derived from the basic propagation equations and numerical solutions are given for both one-wavelength-pump and two-wavelengthpump systems. Several parametric amplifiers driven by pumps at one wavelength and two wavelengths are analyzed and the polarization independent parametric amplifier is proposed.

  7. Polarization Imaging and Insect Vision

    Science.gov (United States)

    Green, Adam S.; Ohmann, Paul R.; Leininger, Nick E.; Kavanaugh, James A.

    2010-01-01

    For several years we have included discussions about insect vision in the optics units of our introductory physics courses. This topic is a natural extension of demonstrations involving Brewster's reflection and Rayleigh scattering of polarized light because many insects heavily rely on optical polarization for navigation and communication.…

  8. THE GENERALIZED POLARIZATION SCATTERING MATRIX

    Science.gov (United States)

    the Least Square Best Estimate of the Generalized Polarization matrix from a set of measurements is then developed. It is shown that the Faraday...matrix data. It is then shown that the Least Square Best Estimate of the orientation angle of a symmetric target is also determinable from Faraday rotation contaminated short pulse monostatic polarization matrix data.

  9. Phenomenological study of polarized leptoproduction

    Energy Technology Data Exchange (ETDEWEB)

    Chiappetta, P.; Girardi, G.

    1989-07-27

    In this note we make a phenomenological study of the recent EMC data on polarized structure function g/sub 1//sup p/(x). Using general principles like Regge behaviour and positivity we derive simple parametrizations for quark and gluon polarized distribution function and obtain a consistent description of experimental data. (orig.).

  10. Mathematical principle and characteristics of polarization transform

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The precise definition of polarization transform is proposed from the viewpoint of polarization domain transform for the first time. The mathematical principle,char-acteristics and physical meanings of polarization transform are analyzed. Two typical kinds of polarization transforms which are called unitary matrix polarization transform (UMPT) and diagonal matrix polarization transform (DMPT) are put for-ward. The gain property and the change property of polarization state distance are presented in detail. Thereby,the concept of serial polarization transform is pro-posed. A general polarization transform can be realized by two steps: changing the location of polarization states in polarization domain by UMPT; and expanding or compressing the density of polarization states by DMPT. The result is meaningful to many applications including polarization filtering,detection,enhancement,anti-jamming,discrimination and so on.

  11. Integrins and epithelial cell polarity.

    Science.gov (United States)

    Lee, Jessica L; Streuli, Charles H

    2014-08-01

    Cell polarity is characterised by differences in structure, composition and function between at least two poles of a cell. In epithelial cells, these spatial differences allow for the formation of defined apical and basal membranes. It has been increasingly recognised that cell-matrix interactions and integrins play an essential role in creating epithelial cell polarity, although key gaps in our knowledge remain. This Commentary will discuss the mounting evidence for the role of integrins in polarising epithelial cells. We build a model in which both inside-out signals to polarise basement membrane assembly at the basal surface, and outside-in signals to control microtubule apical-basal orientation and vesicular trafficking are required for establishing and maintaining the orientation of epithelial cell polarity. Finally, we discuss the relevance of the basal integrin polarity axis to cancer. This article is part of a Minifocus on Establishing polarity.

  12. Generalized Expression for Polarization Density

    Energy Technology Data Exchange (ETDEWEB)

    Lu Wang and T.S. Hahm

    2009-04-23

    A general polarization density which consists of classical and neoclassical parts is system-atically derived via modern gyrokinetics and bounce-kinetics by employing a phase-space Lagrangian Lie-transform perturbation method. The origins of polarization density are further elucidated. Extending the work on neoclassical polarization for long wavelength compared to ion banana width [M. N. Rosenbluth and F. L. Hinton, Phys. Rev. Lett. 80, 724 (1998)], an analytical formula for the generalized neoclassical polarization including both finite-banana-width (FBW) and finite-Larmor-radius (FLR) effects for arbitrary radial wavelength in comparison to banana width and gyroradius is derived. In additional to the contribution from trapped particles, the contribution of passing particles to the neoclassical polarization is also explicitly calculated. Our analytic expression agrees very well with the previous numerical results for a wide range of radial wavelength.

  13. Sir David Brewster: polarization pioneer

    Science.gov (United States)

    Coulson, Kinsell L.

    1992-12-01

    Sir David Brewster, Scottish physicist of the Nineteenth Century, was one of the pioneers in the investigation of the polarization of light. Every physics student is familiar with the Brewster angle of reflection, and the Brewster neutral point of skylight polarization is a well- known feature in atmospheric optics. He was at one time the most honored natural philosopher in Britain, having received numerous medals plus a knighthood for his work in the polarization of light. This paper, having arisen from my new biography of Brewster, traces his polarization work throughout his most productive period in the first half of the last century. It is of interest to science historians, as well as to those working in the field of polarization phenomena.

  14. U.S. polar icebreakers

    Science.gov (United States)

    Brigham, Lawson W.

    1984-04-01

    An interagency study of the nation's polar ice-breaking requirements through the end of the century was recently completed. The Polar Icebreaker Requirements Study (PIRS) Group presented fleet size alternatives and recommended that the Icebreaker User Council define the capabilities required for new icebreakers. The User Council consists of representatives from the U.S. Navy, National Science Foundation, the Maritime Administration, and the U.S. Coast Guard.Polar icebreakers are needed for three basic purposes: (1) resupply of Antarctic and Greenland stations, (2) logistical support of polar operations, and (3) scientific research. One of the PIRS recommendations was that any new icebreaker designs should enhance science support while meeting the requirements for escort and logistics. The U.S. Coast Guard will soon begin the preliminary design for a new class of polar icebreakers.

  15. Ion Polarization Scheme for MEIC

    CERN Document Server

    Kondratenko, A M; Filatov, Yu N; Derbenev, Ya S; Lin, F; Morozov, V S; Zhang, Y

    2016-01-01

    The choice of a figure 8 shape for the booster and collider rings of MEIC opens wide possibilities for preservation of the ion polarization during beam acceleration as well as for control of the polarization at the collider's interaction points. As in the case of accelerators with Siberian snakes, the spin tune is energy independent but is equal to zero instead of one half. The figure-8 topology eliminates the effect of arcs on the spin motion. There appears a unique opportunity to control the polarization of any particle species including deuterons, using longitudinal fields of small integrated strength (weak solenoids). Contrary to existing schemes, using weak solenoids in figure-8 colliders, one can control the polarization at the interaction points without essentially any effect on the beam's orbital characteristics. A universal scheme for control of the polarization using weak solenoids provides an elegant solution to the problem of ion acceleration completely eliminating resonant beam depolarization. It...

  16. Polarization of perceived Procedural Justice.

    Science.gov (United States)

    Flint, Douglas H; Hernandez-Marrero, Pablo; Wielemaker, Martin

    2006-02-01

    This study examined polarization of perceptions of Procedural Justice. Two polarization mechanisms are examined, Persuasive Arguments and Social Comparisons. Participants were students enrolled in a first-year introductory business class. There were 216 participants in the Persuasive Arguments study, 429 in the Social Comparisons study. The average age of all participants was 22.3 yr. (SD = 2.1); 56% were women. Fields of study represented were business, engineering, information technology, and sports. Analysis showed under conditions of low Procedural Justice, polarization effects were only found with the Persuasive Arguments mechanism. Under conditions of high Procedural Justice, polarization effects were only found with Social Comparisons. Implications for group polarization and Procedural Justice theories are considered.

  17. How polar are choline chloride-based deep eutectic solvents?

    Science.gov (United States)

    Pandey, Ashish; Rai, Rewa; Pal, Mahi; Pandey, Siddharth

    2014-01-28

    Developing and characterizing green solvents with low toxicity and cost is one of the most important issues in chemistry. Deep Eutectic Solvents (DESs), in this regard, have shown tremendous promise. Compared to popular organic solvents, DESs possess negligible VOCs and are non-flammable. Compared to ionic liquids, which share many characteristics but are ionic compounds and not ionic mixtures, DESs are cheaper to make, much less toxic and mostly biodegradable. An estimate of the polarity associated with DESs is essential if they are to be used as green alternatives to common organic solvents in industries and academia. As no one physical parameter can satisfactorily represent solute-solvent interactions within a medium, polarity of DESs is assessed through solvatochromic optical spectroscopic responses of several UV-vis absorbance and molecular fluorescence probes. Information on the local microenvironment (i.e., the cybotactic region) that surrounds several solvatochromic probes [betaine dye, pyrene, pyrene-1-carboxaldehyde, 1-anilino-8-naphthalene sulfonate (ANS), p-toluidinyl-6-naphthalene sulfonate (TNS), 6-propionyl-2-(dimethylaminonaphthalene) (PRODAN), coumarin-153, and Nile Red] for four common and popular DESs formed from choline chloride combined with 1,2-ethanediol, glycerol, urea, and malonic acid, respectively, in 1 : 2 molar ratios termed ethaline, glyceline, reline, and maline is obtained and used to assess the effective polarity afforded by each of these DESs. The four DESs as indicated by these probe responses are found to be fairly dipolar in nature. Absorbance probe betaine dye and fluorescence probes ANS, TNS, PRODAN, coumarin-153, and Nile Red, whose solvatochromic responses are based on photoinduced charge-transfer, imply ethaline and glyceline, DESs formed using alcohol-based H-bond donors, to be relatively more dipolar in nature as compared to reline and maline. The pyrene polarity scale, which is based on polarity-induced changes in

  18. Spectral, stoichiometric ratio, physicochemical, polarity and photostability studies of newly synthesized chalcone dye in organized media

    Energy Technology Data Exchange (ETDEWEB)

    Marwani, Hadi M., E-mail: hmarwani@kau.edu.sa [Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia); Center of Excellence for Advanced Materials Research, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia); Asiri, Abdullah M. [Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia); Center of Excellence for Advanced Materials Research, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia); Khan, Salman A. [Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia)

    2013-04-15

    The main focus of this study was to investigate spectroscopic properties, stoichiometric ratios, physicochemical parameters, polarity and photostability behaviors of newly synthesized chalcone dye in organized media. The chalcone dye, 1-(2,5-Dimethyl-thiophen-3-yl)-3-(9-etnyl-9H-carbazol-3-yl)-propenone (DTEP), was prepared by the reaction of carbazole aldehyde with 3-acetyl-2,5-dimethythiophene. Data obtained from FT-IR, {sup 1}H-–NMR, {sup 13}C-NMR and elemental analysis were consistent with chemical structure of newly prepared DTEP. Increases in fluorescence intensities of DTEP with cetyltrimethyl ammonium bromide (CTAB) were observed. In comparison of fluorescence intensities for DTEP with CTAB, reductions in fluorescence intensities for DTEP with sodium dodecyl sulfate (SDS) were noticed under the same experimental and instrumental conditions. Additionally, Benesi–Hildebrand method was applied to determine stoichiometric ratios and association constants of DTEP with CTAB and SDS. Stern–Volmer plot was used in order to further confirm the stoichiometric ratio and association constant of DTEP with SDS. Physicochemical parameters such as singlet absorption, molar absorptivity, oscillator strength, dipole moment and fluorescence quantum yield of DTEP were also determined. Fluorescence polarity study displayed that DTEP was sensitive to the polarity of the microenvironment provided by different solvents. Finally, fluorescence steady-state measurements revealed that DTEP has high photostability against photobleaching. -- Highlights: ► Mechanistic understanding of molecular structure of newly synthesized chalcone dye. ► Exploring spectral behaviors and physicochemical parameters of chalcone dye. ► Determination of stoichiometric ratios and association constants of chalcone dye. ► Determination of fluorescence quantum yield in different solvents. ► High photostability against photobleaching of chalcone dye was observed.

  19. Modular generation of fluorescent phycobiliproteins.

    Science.gov (United States)

    Wu, Xian-Jun; Chang, Kun; Luo, Juan; Zhou, Ming; Scheer, Hugo; Zhao, Kai-Hong

    2013-06-01

    Phycobiliproteins are brightly-fluorescent light-harvesting pigments for photosynthesis in cyanobacteria and red algae. They are also of interest as fluorescent biomarkers, but their heterologous generation in vivo has previously required multiple transformations. We report here a modular approach that requires only two DNA segments. The first codes for the apo-protein. The second codes for fusions capable of chromophore biosynthesis and its covalent attachment to the apo-protein; it contains the genes of heme oxygenase, a bilin reductase, and a chromophore lyase. Phycobiliproteins containing phycoerythrobilin (λ(fluor) ~ 560 nm), phycourobilin (λ(fluor) ~ 500 nm), phycocyanobilin (λ(fluor) ~ 630 nm) or phycoviolobilin (λ(fluor) ~ 580 nm) were obtained in high yield in E. coli. This approach facilitates chromophorylation studies of phycobiliproteins, as well as their use for fluorescence labeling based on their high fluorescence.

  20. Fluorescence diagnosis in tissue injury

    Science.gov (United States)

    Maciel, Vitória H.; Ferreira, Juliana; Bagnato, Vanderlei S.

    2009-06-01

    Background and Objectives: The paper aim was to evaluate the efficacy of the fluorescence spectroscopy in the detection of UV-induced skin change of Wistar rats. Study Design/ Materials and Methods: In a group male Wistar rats, the skin damage was produced by an UV-C lamp, periodically monitored using the laser-induced fluorescence, until complete healing process. After determining a characteristic emission band present in the fluorescence spectra of the induced injuries, the amplitude band monitoring allowed the follow up on the injury and the recovery. Results: We observed the appearance of two new emission bands more evident at the injury spectra when compared to the spectrums from normal non-exposed tissue. Following such spectral bands was possible to observe the establishment and recovery. Conclusions: The fluorescence spectroscopy is a promising technique in distinguishing between normal and UV induced skin change helping the evaluation of changes which are irreversible cancer tissue characteristics.

  1. Fluorescent Sensors for Biological Applications

    Directory of Open Access Journals (Sweden)

    Hui-wang Ai

    2014-09-01

    Full Text Available Fluorescence is one of the most important analytical methods used in biological studies. In the past decade or two, instrumentation in this field has greatly advanced, and now it is possible to detect single photons or fluorescent molecules [1,2], or break the Abbe diffraction limit to distinguish two points spaced less than 50 nm apart [3]. Concurrently, the development of improved fluorescent probes, which can be coupled with state-of-the-art instruments, has been equally important. This special issue on “fluorescent biosensors” in Sensors reports recent results from eight research groups in the field of sensor development. It includes three review articles, and six research articles reporting original results. [...

  2. Lunar true polar wander inferred from polar hydrogen.

    Science.gov (United States)

    Siegler, M A; Miller, R S; Keane, J T; Laneuville, M; Paige, D A; Matsuyama, I; Lawrence, D J; Crotts, A; Poston, M J

    2016-03-24

    The earliest dynamic and thermal history of the Moon is not well understood. The hydrogen content of deposits near the lunar poles may yield insight into this history, because these deposits (which are probably composed of water ice) survive only if they remain in permanent shadow. If the orientation of the Moon has changed, then the locations of the shadowed regions will also have changed. The polar hydrogen deposits have been mapped by orbiting neutron spectrometers, and their observed spatial distribution does not match the expected distribution of water ice inferred from present-day lunar temperatures. This finding is in contrast to the distribution of volatiles observed in similar thermal environments at Mercury's poles. Here we show that polar hydrogen preserves evidence that the spin axis of the Moon has shifted: the hydrogen deposits are antipodal and displaced equally from each pole along opposite longitudes. From the direction and magnitude of the inferred reorientation, and from analysis of the moments of inertia of the Moon, we hypothesize that this change in the spin axis, known as true polar wander, was caused by a low-density thermal anomaly beneath the Procellarum region. Radiogenic heating within this region resulted in the bulk of lunar mare volcanism and altered the density structure of the Moon, changing its moments of inertia. This resulted in true polar wander consistent with the observed remnant polar hydrogen. This thermal anomaly still exists and, in part, controls the current orientation of the Moon. The Procellarum region was most geologically active early in lunar history, which implies that polar wander initiated billions of years ago and that a large portion of the measured polar hydrogen is ancient, recording early delivery of water to the inner Solar System. Our hypothesis provides an explanation for the antipodal distribution of lunar polar hydrogen, and connects polar volatiles to the geologic and geophysical evolution of the Moon

  3. X-ray fluorescence holography

    CERN Document Server

    Hayashi, K; Takahashi, Y

    2003-01-01

    X-ray fluorescence holography (XFH) is a new structural analysis method of determining a 3D atomic arrangement around fluorescing atoms. We developed an XFH apparatus using advanced X-ray techniques and succeeded in obtaining high-quality hologram data. Furthermore, we introduced applications to the structural analysis of a thin film and the environment around dopants and, discussed the quantitative analysis of local lattice distortion. (author)

  4. Fiber based polarization filter for radially and azimuthally polarized light.

    Science.gov (United States)

    Jocher, Christoph; Jauregui, Cesar; Voigtländer, Christian; Stutzki, Fabian; Nolte, Stefan; Limpert, Jens; Tünnermann, Andreas

    2011-09-26

    We demonstrate a new fiber based concept to filter azimuthally or radially polarized light. This concept is based on the lifting of the modal degeneracy that takes place in high numerical aperture fibers. In such fibers, the radially and azimuthally polarized modes can be spectrally separated using a fiber Bragg grating. As a proof of principle, we filter azimuthally polarized light in a commercially available fiber in which a fiber Bragg grating has been written by a femtosecond pulsed laser. © 2011 Optical Society of America

  5. Internal polarization limits coronagraph contrast

    Science.gov (United States)

    Breckinridge, James Bernard; Lam, Wai Sze T.; Chipman, Russell A.

    2015-08-01

    The performance of exoplanet imaging coronagraphs is limited by internal polarization. The point spread function (PSF) of these systems is determined by the details of the opto-mechanical layout selected to package the system and by the highly reflective metal thin films needed to maintain high optical system transmittance. To obtain the high contrast levels needed for terrestrial exoplanet science requires a comprehensive understanding of the vector electromagnetic wave from the source through the system. The literature contains many studies of polarization transmissivity of telescopes and instruments for the purpose of photo-polarimetry. Here we report for the first time the effects of polarization on high-performance image quality.We modeled a typical 2.4-meter Cassegrain telescope system with one 90-degree fold mirror and analyzed the system for polarization aberrations.We find: 1. The image plane irradiance distribution is the linear superposition of four PSF images: One for each of the two orthogonal polarizations and one for each of two cross-product polarization terms. 2. The PSF image is brighter by 9% for one polarization component compared to its orthogonal state. 3. The image of the PSF for orthogonal components are shifted across the focal plane with respect to each other, causing the PSF image for astronomical sources (polarized or unpolarized) to become slightly elongated (elliptical) with a centroid separation of about 0.6 masec. 4. The orthogonally polarized components of unpolarized sources contain different wavefront aberrations, which are separated by approximately 32 milliwaves. This implies that a wavefront correction system cannot optimally correct the aberrations for all polarizations simultaneously. 5. The polarization aberrations couple small parts (~1E-5) of each polarization component of the light into the orthogonal polarization to create highly distorted secondary, or “ghost” PSF image.. The radius of the spatial extent of the 90

  6. Resonance fluorescence from an asymmetric quantum dot dressed by a bichromatic electromagnetic field

    Science.gov (United States)

    Kryuchkyan, G. Yu.; Shahnazaryan, V.; Kibis, O. V.; Shelykh, I. A.

    2017-01-01

    We present the theory of resonance fluorescence from an asymmetric quantum dot driven by a two-component electromagnetic field with two different frequencies, polarizations, and amplitudes (bichromatic field) in the regime of strong light-matter coupling. It follows from the elaborated theory that the broken inversion symmetry of the driven quantum system and the bichromatic structure of the driving field result in unexpected features of the resonance fluorescence, including the infinite set of Mollow triplets, the quench of fluorescence peaks induced by the dressing field, and the oscillating behavior of the fluorescence intensity as a function of the dressing field amplitude. These quantum phenomena are of general physical nature and, therefore, can take place in various double-driven quantum systems with broken inversion symmetry.

  7. Photoinduced electron transfer and fluorescence mechanisms in covalently linked polynuclear aromatic-nucleotide complexes

    Energy Technology Data Exchange (ETDEWEB)

    Geacintov, N.E.; Mao, Bing; Zhao, Rushen; Chen, Junxin; Liu, Tong Ming; Ya, Nai-Qi [New York Univ., NY (United States). Dept. of Chemistry; France, L.L.; Sutherland, J.D. [Brookhaven National Lab., Upton, NY (United States)

    1992-04-01

    The fluorescence of polycyclic aromatic hydrocarbon-nucleic acid complexes is quenched by photoinduced electron transfer mechanisms in aqueous solutions at ambient temperatures. These effects are illustrated with the biologically important compound benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE), a mutagenic and carcinogenic metabolite of the environmental pollutant benzo[a]pyrene, which forms covalent mutagenic lesions with 2{prime}-deoxyguanosine (dG) residues in DNA. The dependence of the fluroescence yeild and fluorescence decay times of the covalent model adduct (+)-trans-BPDE-N{sup 2}-dG as a function of temperature and methanol/water composition are described. Because of the sensitivity of the fluorescence of the pyrenyl residue to the polarity of the microenvironment, the magnitude of the fluorescence yield can be used to distinguish between highly hydrophobic (e.g. intercalation) and other more solvent-exposed BPDE-nucleic acid binding sites.

  8. Photoinduced electron transfer and fluorescence mechanisms in covalently linked polynuclear aromatic-nucleotide complexes

    Energy Technology Data Exchange (ETDEWEB)

    Geacintov, N.E.; Mao, Bing; Zhao, Rushen; Chen, Junxin; Liu, Tong Ming; Ya, Nai-Qi (New York Univ., NY (United States). Dept. of Chemistry); France, L.L.; Sutherland, J.D. (Brookhaven National Lab., Upton, NY (United States))

    1992-01-01

    The fluorescence of polycyclic aromatic hydrocarbon-nucleic acid complexes is quenched by photoinduced electron transfer mechanisms in aqueous solutions at ambient temperatures. These effects are illustrated with the biologically important compound benzo(a)pyrene-7,8-diol-9,10-epoxide (BPDE), a mutagenic and carcinogenic metabolite of the environmental pollutant benzo(a)pyrene, which forms covalent mutagenic lesions with 2{prime}-deoxyguanosine (dG) residues in DNA. The dependence of the fluroescence yeild and fluorescence decay times of the covalent model adduct (+)-trans-BPDE-N{sup 2}-dG as a function of temperature and methanol/water composition are described. Because of the sensitivity of the fluorescence of the pyrenyl residue to the polarity of the microenvironment, the magnitude of the fluorescence yield can be used to distinguish between highly hydrophobic (e.g. intercalation) and other more solvent-exposed BPDE-nucleic acid binding sites.

  9. Fluorescent Ensemble Based on Bispyrene Fluorophore and Surfactant Assemblies: Sensing and Discriminating Proteins in Aqueous Solution.

    Science.gov (United States)

    Fan, Junmei; Ding, Liping; Bo, Yu; Fang, Yu

    2015-10-14

    A particular bispyrene fluorophore (1) with two pyrene moieties covalently linked via a hydrophilic spacer was synthesized. Fluorescence measurements reveal that the fluorescence emission of 1 could be well modulated by a cationic surfactant, dodecyltrimethylammonium bromide (DTAB). Protein sensing studies illustrate that the selected ensemble based on 1/DTAB assemblies exhibits ratiometric responses to nonmetalloproteins and turn-off responses to metalloproteins, which can be used to differentiate the two types of proteins. Moreover, negatively charged nonmetalloproteins can be discriminated from the positively charged ones according to the difference in ratiometric responses. Fluorescence sensing studies with control bispyrenes indicate that the polarity of the spacer connecting two pyrene moieties plays an important role in locating bispyrene fluorophore in DTAB assemblies, which further influences its sensing behaviors to noncovalent interacting proteins. This study sheds light on the influence of the probe structure on the sensing performance of a fluorescent ensemble based on probe and surfactant assemblies.

  10. Fluorescence lifetimes: fundamentals and interpretations.

    Science.gov (United States)

    Noomnarm, Ulai; Clegg, Robert M

    2009-01-01

    Fluorescence measurements have been an established mainstay of photosynthesis experiments for many decades. Because in the photosynthesis literature the basics of excited states and their fates are not usually described, we have presented here an easily understandable text for biology students in the style of a chapter in a text book. In this review we give an educational overview of fundamental physical principles of fluorescence, with emphasis on the temporal response of emission. Escape from the excited state of a molecule is a dynamic event, and the fluorescence emission is in direct kinetic competition with several other pathways of de-excitation. It is essentially through a kinetic competition between all the pathways of de-excitation that we gain information about the fluorescent sample on the molecular scale. A simple probability allegory is presented that illustrates the basic ideas that are important for understanding and interpreting most fluorescence experiments. We also briefly point out challenges that confront the experimenter when interpreting time-resolved fluorescence responses.

  11. Fluorescence detection of esophageal neoplasia

    Science.gov (United States)

    Borisova, E.; Vladimirov, B.; Avramov, L.

    2008-06-01

    White-light endoscopy is well-established and wide used modality. However, despite the many technological advances that have been occurred, conventional endoscopy is suboptimal and usually detects advanced stage lesions. The limitations of standard endoscopy initiate development of spectroscopic techniques, additional to standard endoscopic equipment. One of the most sensitive approaches is fluorescence spectroscopy of gastrointestinal mucosa for neoplasia detection. In the recent study delta-aminolevulinic acid/Protoporphyrin IX (5-ALA/PpIX) is used as fluorescent marker for dysplasia and tumor detection in esophagus. The 5-ALA is administered per os six hours before measurements at dose 20 mg/kg weight. Excitation source has max of emission at 405 nm and light is delivered by the standard light guide of the endoscopic equipment. Through endoscopic instrumental channel a fiber is applied to return information about fluorescence to microspectrometer. Spectral features observed during endoscopic investigations could be distinct as the next regions: 450-630 nm region, where tissue autofluorescence is observed; 630-710 nm region, where fluorescence of PpIX is clearly pronounced; 530-580 nm region, where minima in the autofluorescence signal are observed, related to reabsorption of blood. The lack of fluorescence peaks in the red spectral area for normal mucosa is an indication for selective accumulation of 5-ALA/PpIX only in abnormal sites Very good correlation between fluorescence signals and histology examination of the lesions investigated is achieved.

  12. Classical Maxwellian polarization entanglement

    CERN Document Server

    Carroll, John E

    2015-01-01

    An explanation of polarization entanglement is presented using Maxwells classical electromagnetic theory.Two key features are required to understand these classical origins.The first is that all waves diffract and weakly diffracting waves,with a principal direction of propagation in the laboratory frame, travel along that direction at speeds ever so slightly less than c.This allows nontrivial Lorentz transformations that can act on selected forward F waves or selected waves R traveling in the opposite direction to show that both can arise from a single zero momentum frame where all the waves are transverse to the original principal direction.Such F and R waves then both belong to a single relativistic entity where correlations between the two are unremarkable.The second feature requires the avoidance of using the Coulomb gauge.Waves, tending to plane waves in the limit of zero diffraction,can then be shown to be composed of two coupled sets of E and B fields that demonstrate the classical entanglement of F an...

  13. Compact waveguide circular polarizer

    Science.gov (United States)

    Tantawi, Sami G.

    2016-08-16

    A multi-port waveguide is provided having a rectangular waveguide that includes a Y-shape structure with first top arm having a first rectangular waveguide port, a second top arm with second rectangular waveguide port, and a base arm with a third rectangular waveguide port for supporting a TE.sub.10 mode and a TE.sub.20 mode, where the end of the third rectangular waveguide port includes rounded edges that are parallel to a z-axis of the waveguide, a circular waveguide having a circular waveguide port for supporting a left hand and a right hand circular polarization TE.sub.11 mode and is coupled to a base arm broad wall, and a matching feature disposed on the base arm broad wall opposite of the circular waveguide for terminating the third rectangular waveguide port, where the first rectangular waveguide port, the second rectangular waveguide port and the circular waveguide port are capable of supporting 4-modes of operation.

  14. POLARIZED LIGHT IN PHYSIOTHERAPY

    Directory of Open Access Journals (Sweden)

    L. D. Tondiy

    2015-12-01

    Full Text Available The data on polarized light (PS - a new promising treatment, rehabilitation and prevention, which took its deserved place among the known therapeutic physical factors and may even compete with laser radiation of low and LED therapy. It is reflected the significant contribution of domestic scientists in the study of aircraft action on the body, its introduction in the treatment, rehabilitation and prevention of grippe, ARI. These action's mechanisms of the aircraft on the electro-physiological processes in the body that have the leading role in the regulation of its life. The new moment in the study of aircraft on the body is the evidence of its positive impact on the mechanisms of self body - its different units: the disease's banning - a revitalization of the stress-protective, stress-limiting system antioxidial, detoxification and other protection systems, the formation by the body antiviral and antimicrobial specific substances (interferon and lysozyme, activation of the immune system, phagocytosis, protective functions of skin. The protective and mobilizing role of the second link is studied: which is triggered in case of occurrence of disease or preexisting diseases: PL mobilized processes of restitution, reparations, compensation, immunity and microcirculation. The authors studied the possibility of aircraft's using to enhance performance, reduce side effects of physical factors, which are often used in the treatment (electric methods, treatment by sound, fresh and mineral water, etc..

  15. Update of the Polar SWIFT model for polar stratospheric ozone loss (Polar SWIFT version 2)

    Science.gov (United States)

    Wohltmann, Ingo; Lehmann, Ralph; Rex, Markus

    2017-07-01

    The Polar SWIFT model is a fast scheme for calculating the chemistry of stratospheric ozone depletion in polar winter. It is intended for use in global climate models (GCMs) and Earth system models (ESMs) to enable the simulation of mutual interactions between the ozone layer and climate. To date, climate models often use prescribed ozone fields, since a full stratospheric chemistry scheme is computationally very expensive. Polar SWIFT is based on a set of coupled differential equations, which simulate the polar vortex-averaged mixing ratios of the key species involved in polar ozone depletion on a given vertical level. These species are O3, chemically active chlorine (ClOx), HCl, ClONO2 and HNO3. The only external input parameters that drive the model are the fraction of the polar vortex in sunlight and the fraction of the polar vortex below the temperatures necessary for the formation of polar stratospheric clouds. Here, we present an update of the Polar SWIFT model introducing several improvements over the original model formulation. In particular, the model is now trained on vortex-averaged reaction rates of the ATLAS Chemistry and Transport Model, which enables a detailed look at individual processes and an independent validation of the different parameterizations contained in the differential equations. The training of the original Polar SWIFT model was based on fitting complete model runs to satellite observations and did not allow for this. A revised formulation of the system of differential equations is developed, which closely fits vortex-averaged reaction rates from ATLAS that represent the main chemical processes influencing ozone. In addition, a parameterization for the HNO3 change by denitrification is included. The rates of change of the concentrations of the chemical species of the Polar SWIFT model are purely chemical rates of change in the new version, whereas in the original Polar SWIFT model, they included a transport effect caused by the

  16. Polarization transmission at RHIC, numerical simulations

    Energy Technology Data Exchange (ETDEWEB)

    Meot F.; Bai, M.; Liu, C.; Minty, M.; Ranjbar, V.

    2012-05-20

    Typical tracking simulations regarding the transmission of the polarization in the proton-proton collider RHIC are discussed. They participate in general studies aimed at understanding and improving polarization performances during polarized proton-proton runs.

  17. Combined enhanced fluorescence and label-free biomolecular detection with a photonic crystal surface.

    Science.gov (United States)

    Mathias, Patrick C; Ganesh, Nikhil; Chan, Leo L; Cunningham, Brian T

    2007-04-20

    A 2D photonic crystal surface with a different period in each lateral direction is demonstrated to detect biomolecules using two distinct sensing modalities. The sensing mechanisms both rely on the generation of a resonant reflection peak at one of two specific wavelengths, depending on the polarization of light that is incident on the photonic crystal. One polarization results in a resonant reflection peak in the visible spectrum to coincide with the excitation wavelength of a fluorophore, while the orthogonal polarization results in a resonant reflection peak at an infrared wavelength which is used for label-free detection of adsorbed biomolecules. The photonic crystal resonance for fluorescence excitation causes enhanced near fields at the structure surface, resulting in increased signal from fluorophores within 100 nm of the device surface. Label-free detection is performed by illuminating the photonic crystal with white light and monitoring shifts in the peak reflected wavelength of the infrared resonance with a high-resolution imaging detection instrument. Rigorous coupled-wave analysis was used to determine optimal dimensions for the photonic crystal structure, and devices were fabricated using a polymer-based nanoreplica molding approach. Fluorescence-based and label-free detection were demonstrated using arrays of spots of dye-conjugated streptavidin. Quantification of the fluorescent signal showed that the fluorescence output from protein spots on the photonic crystal was increased by up to a factor of 35, and deposited spots were also imaged in the label-free detection mode.

  18. Borghini's Mechanism for Dynamic Polarization in Polarized Targets

    CERN Document Server

    de Boer, Wim

    2015-01-01

    This paper is a contribution to the memorial session for Michel Borghini at the Spin 2014 conference in Bejing, honoring his pivotal role for the development of polarized targets in high energy physics. Borghini proposed for the first time the correct mechanism for dynamic polarization in polarized targets using organic materials doped with free radicals. In these amorphous materials the spin levels are broadened by spin-spin interactions and g-factor anisotropy, which allows a high dynamic polarization of nuclei by cooling of the spin-spin interaction reservoir. In this contribution I summarize the experimental evidence for this mechanism. These pertinent experiments were done at CERN in the years 1971 - 1974, when I was a graduate student under the guidance of Michel Borghini. I finish by shortly describing how Borghini's spin temperature theory is now applied in cancer therapy.

  19. High intensity polarized electron sources

    Energy Technology Data Exchange (ETDEWEB)

    Sinclair, C.K.

    1980-10-01

    The status of the polarized electron source development program at SLAC will be reviewed. Emission currents of 60 A, corresponding to a space charge limited current density of 180 A/cm/sup 2/, have been obtained from GaAs photocathodes. Electron beam polarization 20% greater than that obtainable from GaAs cathodes has been observed from multilayer GaAs-GaAlAs structures. Work in progress to produce high beam polarization from II-IV-V/sub 2/ chalcopyrite photocathodes will also be described.

  20. Remote Sensing in Polarized Light

    Science.gov (United States)

    Whitehead, Victor S.; Coulson, Kinsell L.

    1988-01-01

    Preliminary analysis of polarized images of earth collected by hand-held cameras on Shuttle Missions 51A, 51G, 51I, and 61A indicate that information of the earth's surface and atmosphere exists in those data. To ensure that follow-on research in polarization is focused upon and that the experiments are properly designed to address specific questions, 26 scientists with past experience and interest in polarization observations met at the Lyndon B. Johnson Space Center on November 3 to 5, 1987. This conference report summarizes the discussions and provides the recommendations of the group for follow-on research.

  1. Polarization Filtering of SAR Data

    Science.gov (United States)

    Dubois, Pascale C.; Van Zyl, Jakob J.

    1991-01-01

    Theoretical analysis of polarization filtering of synthetic-aperture-radar (SAR) returns provide hybrid method applied to either (1) maximize signal-to-noise ratio of return from given target or (2) enhance contrast between targets of two different types (that have different polarization properties). Method valid for both point and extended targets and for both monostatic and bistatic radars as well as SAR. Polarization information in return signals provides more complete description of radar-scattering properties of targets and used to obtain additional information about targets for use in classifying them, discriminating between them, or enhancing features of radar images.

  2. Optimization of integrated polarization filters

    CERN Document Server

    Gagnon, Denis; Déziel, Jean-Luc; Dubé, Louis J

    2014-01-01

    This study reports on the design of small footprint, integrated polarization filters based on engineered photonic lattices. Using a rods-in-air lattice as a basis for a TE filter and a holes-in-slab lattice for the analogous TM filter, we are able to maximize the degree of polarization of the output beams up to 98 % with a transmission efficiency greater than 75 %. The proposed designs allow not only for logical polarization filtering, but can also be tailored to output an arbitrary transverse beam profile. The lattice configurations are found using a recently proposed parallel tabu search algorithm for combinatorial optimization problems in integrated photonics.

  3. Thermodynamics of polarized relativistic matter

    Science.gov (United States)

    Kovtun, Pavel

    2016-07-01

    We give the free energy of equilibrium relativistic matter subject to external gravitational and electromagnetic fields, to one-derivative order in the gradients of the external fields. The free energy allows for a straightforward derivation of bound currents and bound momenta in equilibrium. At leading order, the energy-momentum tensor admits a simple expression in terms of the polarization tensor. Beyond the leading order, electric and magnetic polarization vectors are intrinsically ambiguous. The physical effects of polarization, such as the correlation between the magneto-vortically induced surface charge and the electro-vortically induced surface current, are not ambiguous.

  4. Thermodynamics of polarized relativistic matter

    CERN Document Server

    Kovtun, Pavel

    2016-01-01

    We give the free energy of equilibrium relativistic matter subject to external gravitational and electromagnetic fields, to one-derivative order in the gradients of the external fields. The free energy allows for a straightforward derivation of bound currents and bound momenta in equilibrium. At leading order, the energy-momentum tensor admits a simple expression in terms of the polarization tensor. Beyond the leading order, electric and magnetic polarization vectors are intrinsically ambiguous. The physical effects of polarization, such as the correlation between the magneto-vortically induced surface charge and the electro-vortically induced surface current, are not ambiguous.

  5. PolarHub: A Global Hub for Polar Data Discovery

    Science.gov (United States)

    Li, W.

    2014-12-01

    This paper reports the outcome of a NSF project in developing a large-scale web crawler PolarHub to discover automatically the distributed polar dataset in the format of OGC web services (OWS) in the cyberspace. PolarHub is a machine robot; its goal is to visit as many webpages as possible to find those containing information about polar OWS, extract this information and store it into the backend data repository. This is a very challenging task given huge data volume of webpages on the Web. Three unique features was introduced in PolarHub to make it distinctive from earlier crawler solutions: (1) a multi-task, multi-user, multi-thread support to the crawling tasks; (2) an extensive use of thread pool and Data Access Object (DAO) design patterns to separate persistent data storage and business logic to achieve high extendibility of the crawler tool; (3) a pattern-matching based customizable crawling algorithm to support discovery of multi-type geospatial web services; and (4) a universal and portable client-server communication mechanism combining a server-push and client pull strategies for enhanced asynchronous processing. A series of experiments were conducted to identify the impact of crawling parameters to the overall system performance. The geographical distribution pattern of all PolarHub identified services is also demonstrated. We expect this work to make a major contribution to the field of geospatial information retrieval and geospatial interoperability, to bridge the gap between data provider and data consumer, and to accelerate polar science by enhancing the accessibility and reusability of adequate polar data.

  6. Combining fluorescence and bioluminescence microscopy.

    Science.gov (United States)

    Goda, Kazuhito; Hatta-Ohashi, Yoko; Akiyoshi, Ryutaro; Sugiyama, Takashi; Sakai, Ikuko; Takahashi, Takeo; Suzuki, Hirobumi

    2015-08-01

    Bioluminescence microscopy has revealed that gene expression in individual cells can respond differently to the same stimulus. To understand this phenomenon, it is important to sequentially observe the series of events from cellular signal transduction to gene expression regulated by specific transcription factors derived from signaling cascades in individual cells. However, these processes have been separately analyzed with fluorescence and bioluminescence microscopy. Furthermore, in culture medium, the background fluorescence of luciferin-a substrate of luciferase in promoter assays of gene expression in cultured cells-confounds the simultaneous observation of fluorescence and bioluminescence. Therefore, we optimized conditions for optical filter sets based on spectral properties and the luciferin concentration based on cell permeability for fluorescence observation combined with bioluminescence microscopy. An excitation and emission filter set (492-506 nm and 524-578 nm) was suitable for green fluorescent protein and yellow fluorescent protein imaging of cells, and >100 μM luciferin was acceptable in culture medium based on kinetic constants and the estimated intracellular concentration. Using these parameters, we present an example of sequential fluorescence and bioluminescence microscopic observation of signal transduction (translocation of protein kinase C alpha from the cytoplasm to the plasma membrane) coupled with activation of gene expression by nuclear factor of kappa light polypeptide B in individual cells and show that the gene expression response is not completely concordant with upstream signaling following stimulation with phorbol-12-myristate-13-acetate. Our technique is a powerful imaging tool for analysis of heterogeneous gene expression together with upstream signaling in live single cells.

  7. Complexation of serum albumins and triton X-100: Quenching of tryptophan fluorescence and analysis of the rotational diffusion of complexes

    Science.gov (United States)

    Vlasova, I. M.; Vlasov, A. A.; Saletskii, A. M.

    2016-07-01

    The polarized and nonpolarized fluorescence of bovine serum albumin and human serum albumin in Triton X-100 solutions is studied at different pH values. Analysis of the constants of fluorescence quenching for BSA and HSA after adding Triton X-100 and the hydrodynamic radii of BSA/HSA-detergent complexes show that the most effective complexation between both serum albumins and Triton X-100 occurs at pH 5.0, which lies near the isoelectric points of the proteins. Complexation between albumin and Triton X-100 affects the fluorescence of the Trp-214 residing in the hydrophobic pockets of both BSA and HSA.

  8. Multiphoton excitation fluorescence microscopy in planar membrane systems.

    Science.gov (United States)

    Brewer, Jonathan; Bernardino de la Serna, Jorge; Wagner, Kerstin; Bagatolli, Luis A

    2010-07-01

    The feasibility of applying multiphoton excitation fluorescence microscopy-related techniques in planar membrane systems, such as lipid monolayers at the air-water interface (named Langmuir films), is presented and discussed in this paper. The non-linear fluorescence microscopy approach, allows obtaining spatially and temporally resolved information by exploiting the fluorescent properties of particular fluorescence probes. For instance, the use of environmental sensitive probes, such as LAURDAN, allows performing measurements using the LAURDAN generalized polarization function that in turn is sensitive to the local lipid packing in the membrane. The fact that LAURDAN exhibit homogeneous distribution in monolayers, particularly in systems displaying domain coexistence, overcomes a general problem observed when "classical" fluorescence probes are used to label Langmuir films, i.e. the inability to obtain simultaneous information from the two coexisting membrane regions. Also, the well described photoselection effect caused by excitation light on LAURDAN allows: (i) to qualitative infer tilting information of the monolayer when liquid condensed phases are present and (ii) to provide high contrast to visualize 3D membranous structures at the film's collapse pressure. In the last case, computation of the LAURDAN GP function provides information about lipid packing in these 3D structures. Additionally, LAURDAN GP values upon compression in monolayers were compared with those obtained in compositionally similar planar bilayer systems. At similar GP values we found, for both DOPC and DPPC, a correspondence between the molecular areas reported in monolayers and bilayers. This correspondence occurs when the lateral pressure of the monolayer is 26+/-2 mN/m and 28+/-3 mN/m for DOPC and DPPC, respectively.

  9. Temperature effect on 4-aminophtalimide fluorescence in n-alcohols

    Energy Technology Data Exchange (ETDEWEB)

    Dobek, Krzysztof, E-mail: dobas@amu.edu.pl [Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznan (Poland); Karolczak, Jerzy, E-mail: jgkarol@amu.edu.pl [Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznan (Poland); Center For Ultrafast Laser Spectroscopy, Adam Mickiewicz University, Umultowska 85, 61-614 Poznan (Poland)

    2015-09-15

    The compound 4-aminophthalimide (4-AP) is a well-known dye used as an environment polarity sensitive probe e.g. in solvation studies. This paper presents the effect of temperature on 4-aminophthalimides steady-state and time-resolved fluorescence in five n-alcohols. It is shown that the hydrogen bonding ability of n-alcohols affects the shifts of steady-state absorption and fluorescence spectra of 4-aminophthalimide at room temperature, and the shifts of fluorescence also at temperatures from the range 180 to 323 K. Temperature is shown to affect the change in hydrogen bond energy that follows 4-AP excitation, in a way dependent on the n-alcohol alkyl chain length. On the other hand, time-resolved results indicate that the temperature dependence of 4-AP deactivation follows mainly from the energy-gap dependent non-radiative deactivation rate. Fluorescence transition dipole moments at room temperature have been found to be slightly dependent on the solvent, but nothing proves that these changes are connected to different hydrogen bonding character of each n-alcohol. Therefore, while the steady-state results provide clear evidence of hydrogen bonding between 4-AP and n-alcohols, the time-resolved results do not show any evident sign of hydrogen bonding, besides the influence of the position of fluorescence emission on the radiative and non-radiative rates. - Highlights: • We show temperature effect on 4-aminophthalimide (4-AP) absorption and emission. • Hydrogen bonds formation between n-alcohols and 4-AP affect steady-state results. • Temperature change influences hydrogen bonds energy. • 4-AP non-radiative deactivation is energy-gap controlled.

  10. Utilización de los test de Fluorescencia Polarizada (FP y Elisa de Competencia (C-Elisa en el diagnóstico de brucelosis de camélidos The use of polarized fluorescence assay (PF and competitive ELISA test (C-Elisa for the diagnosis of Brucellosis in South American camelids

    Directory of Open Access Journals (Sweden)

    X Rojas

    2004-01-01

    Full Text Available En Chile, como en muchos países de Latinoamérica, la brucelosis es una zoonosis presente, representando no sólo un factor de riesgo para las explotaciones pecuarias sino también para quienes laboran y hacen usufructo de ella, especialmente por el consumo de leche cruda y sus derivados. Como la Brucella afecta a diferentes especies de animales, el objetivo de este trabajo fue utilizar las técnicas de unión primaria, como son Fluorescencia Polarizada (FP y Elisa de Competencia (C-Elisa, para la detección de anticuerpos anti-Brucella en suero de camélidos y, comparar sus respuestas con las pruebas de Rosa de Bengala (RB, Aglutinación Lenta en Tubo (SAT y Fijación de Complemento (FC en atención a que estas especies representan un potencial pecuario de cierta trascendencia. Para ello se analizaron 336 sueros, de los cuales 315 pertenecían a llamas y 21 a alpacas, provenientes de un predio de la Novena Región clínica y serológicamente libre de Brucella. Los resultados obtenidos señalan que el umbral de positividad para FP, calculado según la mediana del último percentil, fue de 98.7 milipolarizaciones (mP y, el corte para C-Elisa con el mismo método fue de 32% de Inhibición (% I. Todas las muestras analizadas dieron resultados negativos a RB y SAT. Los resultados con FC no pudieron ser considerados, por cuanto un alto porcentaje de las muestras fueron anticomplementarias. Con las técnicas de C-Elisa y FP, dos muestras reaccionaron positivamente en cada uno de los test con valores en el nivel de corte o levemente superiores. Se discute la significación de ellas.Brucellosis is a zoonotic disease representing a risk contact with, or consuming, their raw milk and raw dairy several animal species, including camelids, the aim of this Polarization assay (PF and Competitive ELISA (C-ELISA, along with conventional serological tests such as the Rose Complement Fixation test (CF. A total of 336 serum samples herd of the IXth Region (Chile

  11. Polarization measurement analysis III. Analysis of the polarization angle dispersion function with high precision polarization data

    CERN Document Server

    Alina, D; Ristorcelli, I; Bernard, J -P; Levrier, F; Abdikamalov, E

    2016-01-01

    High precision polarization measurements open new opportunities for the study of the magnetic field structure as traced by polarimetric measurements of the interstellar dust emission. Polarization parameters suffer from bias in the presence of measurement noise. It is critical to take into account all the information available in the data in order to accurately derive these parameters. The goal of this paper is to characterize the bias on the polarization angle dispersion function that is used to study the spatial coherence of the polarization angle. We characterize, for the first time, the bias on the conventional estimator of the polarization angle dispersion function (S hereafter) and show that it can be positive or negative depending on the true value. Monte Carlo simulations are performed in order to explore the impact of the noise properties of the polarization data, as well as the impact of the distribution of the true polarization angles on the bias. We show that in the case where the ellipticity of t...

  12. Synthesis and Spectroscopic Investigation of Diketopyrrolopyrrole - Spiropyran Dyad for Fluorescent Switch Application.

    Science.gov (United States)

    Doddi, Siva; Narayanaswamy, K; Ramakrishna, Bheerappagari; Singh, Surya Prakash; Bangal, Prakriti Ranjan

    2016-11-01

    We report the synthesis and characterization of a new fluorescent dyad SP-DPP-SP(9) via efficient palladium-catalyzed Sonogashira coupling of prop-2-yn-1-yl 3-(3',3'dimethyl-6-nitrospiro[chromene-2,2'-indolin]-1'-yl)propanoatespiropyran, SP(8), a well known photochromic accepter, with 3,6-bis(5-bromothiophen-2-yl)-2,5-bis((R)-2-ethylhexyl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione, DPP(4), a highly fluorescent donor. Under visible light exposure the SP unit is in a closed hydrophobic form, whereas under UV irradiation it converts to a polar, hydrophilic open form named Merocyanine (MC), which is responsible for functioning of photo-switch application. The photochemistry pertaining to fluorescence switch, 'on/off' behaviour, of model dyad SP-DPP-SP(9) is experimentally analyzed in solution as well as in solid state in polymer matrices by photoluminescence(PL) and absorption spectroscopy. After absorption of UV light the spiropyran unit of the dyad under goes the rupture of the spiro C-O bond leading to the formation of MC. The absorption band of MC fairly overlaps to the fluorescence of DPP unit resulting quenching of fluorescence via fluorescence resonance energy transfer from exited DPP unit to ground state MC. In contrary, the fluorescence of DPP is fully regained upon transformation of MC to SP by exposure to visible light or thermal stimuli. Hence, the fluorescence intensity of dyad 9 is regulated by reversible conversion among the two states of the photochromic spiropyran units and the fluorescence resonance energy transfer (FRET) between the MC form of SP and the DPP unit. Conversely, these scrutiny of the experiment express that the design of dyad 9 is viable as efficient fluorescent switch molecule in many probable commercial applications, such as, logic gates and photonic and optical communications.

  13. A reflection polarizations zoom metasurfaces

    Science.gov (United States)

    Yang, Fulong; Wang, Xiaoyan

    2017-02-01

    Based on generalized Snell's law, we propose a dual-polarity zoom metasurfaces operating electromagnetic wave in the reflection geometry. The metasurfaces is constructed by two identical ultrathin metal-backed dielectric slabs with metallic Jerusalem cross patterns on the other sides to form a triangular region. The normally incident waves are totally reflected, but the reflection phases of both x- and y-polarized waves are controlled independently. According to the classical theory of optical imaging, the reflection electromagnetic wave phases were obtained in the different polarizations and focus. Each subwavelength units size were determined with the reflection coefficient of the basic unit, the polarizations zoom metasurfaces was designed in the way. The full-wave simulations are in good agreement with theoretical analysis in microwave lengths.

  14. A Novel Polarization Maintaining Fiber

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    It introduces a novel elliptical jacket polarization maintaining fiber, whose SAP is like numeral "1". One preform can be drawn over 8km. Fiber's performances show that it is fit for fiber gyroscope and other sensors.

  15. A Novel Polarization Maintaining Fiber

    Institute of Scientific and Technical Information of China (English)

    Benjamin Xue

    2003-01-01

    It introduces a novel elliptical jacket polarization maintaining fiber, whose SAP is like numeral "1" One preform can be drawn over 8km. Fiber's performances show that it is fit for fiber gyroscope and other sensors.

  16. Organic chemistry: Natural polarity inverted

    Science.gov (United States)

    Romanov-Michailidis, Fedor; Rovis, Tomislav

    2015-07-01

    The concept of umpolung describes the reversal of the naturally occurring electrostatic polarization of chemical groups. It has now been used to make single mirror-image isomers of nitrogen-containing molecules. See Letter p.445

  17. The sensitivity of income polarization

    DEFF Research Database (Denmark)

    Hussain, Azhar

    2009-01-01

    This study looks at polarization and its components' sensitivity to assumptions about equivalence scales, income definition, ethical income distribution parameters, and the income accounting period. A representative sample of Danish individual incomes from 1984 to 2002 is utilised. Results show...

  18. Modulated spin polarization in nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Wedekind, Sebastian; Oka, Hirofumi; Rodary, Guillemin; Sander, Dirk; Kirschner, Juergen [Max-Planck-Institut fuer Mikrostrukturphysik, Halle (Germany)

    2009-07-01

    Deposition of 0.7 ML Co onto the clean Cu(111) surface at room temperature leads to the formation of triangular two atomic layers high Co islands. We study the electronic properties of these nano islands by scanning tunneling microscopy (STM) and spectroscopy (STS) at 7 K. We observe pronounced spatial modulation patterns in the local density of states (LDOS) within the islands due to electron confinement. We explore the magnetic properties of the very same islands by spin-polarized STM and STS in a magnetic field of up to 4 T. Our spin-polarized measurements in field clearly identify the parallel and anti-parallel spin orientation states of tip and sample. This enables us to measure the spatial distribution of the spin polarization within single Co islands. We find that the spin polarization is spatially modulated. Our results are discussed in view of recent theoretical predictions.

  19. Vertical Beam Polarization at MAMI

    Science.gov (United States)

    Schlimme, B. S.; Achenbach, P.; Aulenbacher, K.; Baunack, S.; Bender, D.; Beričič, J.; Bosnar, D.; Correa, L.; Dehn, M.; Distler, M. O.; Esser, A.; Fonvieille, H.; Friščić, I.; Gutheil, B.; Herrmann, P.; Hoek, M.; Kegel, S.; Kohl, Y.; Kolar, T.; Kreidel, H.-J.; Maas, F.; Merkel, H.; Mihovilovič, M.; Müller, J.; Müller, U.; Nillius, F.; Nuck, A.; Pochodzalla, J.; Schoth, M.; Schulz, F.; Sfienti, C.; Širca, S.; Spruck, B.; Štajner, S.; Thiel, M.; Tioukine, V.; Tyukin, A.; Weber, A.

    2017-04-01

    For the first time a vertically polarized electron beam has been used for physics experiments at MAMI in the energy range between 180 and 855 MeV. The beam-normal single-spin asymmetry An, which is a direct probe of higher-order photon exchange beyond the first Born approximation, has been measured in the reaction 12C (e → , e ‧)12C . Vertical polarization orientation was necessary to measure this asymmetry with the existing experimental setup. In this paper we describe the procedure to orient the electron polarization vector vertically, and the concept of determining both its magnitude and orientation with the available setup. A sophisticated method has been developed to overcome the lack of a polarimeter setup sensitive to the vertical polarization component.

  20. Growth habit of polar crystals

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Using coordination polyhedron rule, growth habit of polar crystals such as ZnO, ZnS and SiO2 is investigated. It shows that the growth rates in the positive and negative polar axis directions are different. The theoretical growth habit of ZnO crystal is hexagonal prism and the growth rates of its various faces are:V{0001}>V{0111}-->V{0110}->V{0111}->V{0001}-. The growth habit of ZnS crystal is tetrahedron and its growth rates of different crystal faces are: V{111}>V{001}>V{001} =V{100} =. The growth rate relationship between positive and negative polar axis directions of SiO2 crystal V[1120]-->V[1120]-.is These results are in agreement with the growth habits observed under hydrothermal conditions. The different growth rates between positive and negative polar axis directions cannot be explained by PBC theory.

  1. Producing fluorescent digital printing ink: Investigating the effect of type and amount of coumarin derivative dyes on the quality of ink

    Energy Technology Data Exchange (ETDEWEB)

    Ataeefard, Maryam, E-mail: ataeefard-m@icrc.ac.ir [Department of Printing Science and Technology, Institute for Color Science and Technology, P.O. Box 16765-654, Tehran (Iran, Islamic Republic of); Nourmohammadian, Farahnaz, E-mail: nour@icrc.ac.ir [Centre of Excellence for Colour Science and Technology, Institute for Colour Science and Technology, P.O. Box 16765-654, Tehran (Iran, Islamic Republic of); Department of Organic Colorants, Institute for Colour Science and Technology, P.O. Box 16765-654, Tehran (Iran, Islamic Republic of)

    2015-11-15

    The aim of this work is to produce a composite powder as a fluorescent ink for digital electrophotographic printing. Three benzoxazolyl and benzimidazolyl coumarin derivative dyes are used as fluorescent dyes that are incorporated into poly (styrene-co-a crylic acid) using eco-friendly emulsion aggregation (EA) approaches in several amounts with final application of fluorescent laser printing ink called toner. Fluorescence and daylight spectrophotometry is used for investigating the emission and reflectance properties of fluorescent toner. It was found that the relations between emission of fluorescent toners and the amount of dyes are non-linear. Particle size analysis, scanning electron microscopy, differential scanning calorimeter and thermal gravimetric analysis were used to study the size, shape, morphology and thermal properties of fluorescent toner particles. Results verify that the polarity of the dyes and their compatibility with the environment could affect the shape of the fluorescent toner. In addition, the results show that the fluorescent toner produced by the EA method has appropriate characteristics comparing to an industrial toner. - Highlights: Fluorescent digital printing ink produced via emulsion aggregation technique. Fluorescent ink for produced for electrophotographic printing. The relations between fluorescent emission and the amount of dyes are non-linear. Different dyes, show different behavior.

  2. Multiparametric probing of microenvironment with solvatochromic fluorescent dyes.

    Science.gov (United States)

    Klymchenko, Andrey S; Demchenko, Alexander P

    2008-01-01

    We describe new methodology for multiparametric probing of weak non-covalent interactions in the medium based on response of environment-sensitive fluorescent dyes. The commonly used approach is based on correlation of one spectroscopic parameter (e.g. wavelength shift) with environment polarity, which describes a superposition of universal and specific (such as hydrogen bonding) interactions. In our approach, by using several independent spectroscopic parameters of a dye, we monitor simultaneously each individual type of the interactions. For deriving these extra parameters the selected dye should exist in several excited and/or ground states. In the present work, we applied 4'-(diethylamino)-3-hydroxyflavone, which undergoes the excited-state intramolecular proton transfer (ESIPT) and thus exhibits an additional emission band belonging to an ESIPT product (tautomer) form of the dye. The spectroscopic characteristics of the excited normal and the tautomer states as well as of the ESIPT reaction of the dye are differently sensitive to the different types of interactions with microenvironment and therefore can be used for its multiparametric description. The new methodology allowed us to monitor simultaneously three fundamental physicochemical parameters of probe microenvironment: polarity, electronic polarizability and H-bond donor ability. The applications of this approach to binary solvent mixtures, reverse micelles, lipid bilayers and binding sites of proteins are presented and the limitations of this approach are discussed. We believe that the methodology of multiparametric probing will extend the capabilities of fluorescent probes as the tools in biomolecular and cellular research.

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

    Science.gov (United States)

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

    2017-01-01

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

  4. Sum rule distortions in fluorescence-yield x-ray magnetic circular dichroism

    Science.gov (United States)

    Liu, Boyang; Piamonteze, Cinthia; Delgado-Jaime, Mario Ulises; Wang, Ru-Pan; Heidler, Jakoba; Dreiser, Jan; Chopdekar, Rajesh; Nolting, Frithjof; de Groot, Frank M. F.

    2017-08-01

    The quantitative analysis of 3 d transition metal L2 ,3 edge x-ray magnetic circular dichroism (XMCD) spectra and the related sum rules are compared for measurements with electron yield and fluorescence yield detection. Multiplet calculations on divalent ions show that fluorescence yield detected sum rule derived expectation values of Lz and Sz show noticeable deviations and detection angle dependence. We show that small deviations of the polarization dependent fluorescent decay values lead to significant deviations in the Lz and Sz sum rule values. Fe and Co experimental XMCD spectra of a supported 10 nm CoFe2O4 thin film are measured simultaneously by both electron and fluorescence yield. The deviations shown in the experimental data are well explained by the calculations and are shown to mainly depend on the polarization dependent total decay. We conclude that fluorescence yield detected x-ray magnetic circular dichroism is unsuitable for quantitative analysis of the Lz and Sz sum rule values.

  5. Fluorescence enhancement and focal volume reduction observed in c-shaped nano-apertures

    Science.gov (United States)

    Yuen, Yin; Fore, Samantha; Huser, Thomas; Hesselink, Lambertus

    2008-02-01

    We evaluate the potential ability of c-shaped apertures milled in aluminum thin films to reduce the effective measurement volume and to enhance the fluorescence signal for fluorescence correlation spectroscopy of ATTO655 dye dissolved in a HEPES buffer solution. Previous studies have shown that by morphing a square aperture into a rectangular aperture while holding the cross-sectional area constant will yield strong polarization dependence in the reduction of the effective volume and about a factor of 2-3 enhancement in the fluorescence count rate per molecule. By morphing the rectangular aperture into a c-shaped aperture we gain further reduction in focal volume while maintaining the count rate enhancements. In particular, we compare c-shaped apertures to squares with the same cross-sectional area and show that one can achieve one molecule per focal volume at ~3µM (about a 1000 times reduction in effective volume compared to confocal FCS) while maintaining a fluorescence count rate per molecule of about an order of magnitude higher than for bulk diffusing dyes. Two orthogonal polarizations for the incident field have been studied to explore the effects on the focal volume reduction and fluorescence count rate enhancements.

  6. Gallstone identification by fluorescence spectroscopy

    Science.gov (United States)

    Pradhan, Asima; Laxmi, B. V.; Jena, Sidhartha S.; Khulbe, P. K.; Bist, Hari D.; Agarwal, Asha

    1998-04-01

    Gallstones have been classified as being cholesterol type and pigment type. The classification is important for diet control of the patient to avoid recurrence of the stone. Spectroscopy is a sensitive technique to determine the composition of the gallstone both in-vitro and in-vivo. this work deals with the fluorescence spectroscopy of gallstone. For fluorescence spectroscopic studies of gallstone, samples were excited with 5 mw of 488 nm line of argon-ion laser and spectra were recorded with a SPEX 1877E triplemate attached with a cooled PMT and DM3000R data acquisition system. Fluorescence spectra from pure cholesterol and bilirubin were also recorded for comparison. Different types of gallstones: mixed, cholesterol, pigment type were studied. All spectra exhibited a very broad band, 500 to 800 nm and sometimes two bands, depending on type of stone. Pure cholesterol shows three prominent fluorescence peaks at 513, 550, 583 nm along with two peaks at approximately 568 and 586 nm. Pure bilirubin shows prominent peak at 628 nm, without any Raman line. From fluorescence spectra different types of stones are identified. Different gallstones studied show a mixture of cholesterol and bilirubin types and the ratio of the two varies from one sample type to another.

  7. Cell polarity proteins and spermatogenesis.

    Science.gov (United States)

    Gao, Ying; Xiao, Xiang; Lui, Wing-Yee; Lee, Will M; Mruk, Dolores; Cheng, C Yan

    2016-11-01

    When the cross-section of a seminiferous tubule from an adult rat testes is examined microscopically, Sertoli cells and germ cells in the seminiferous epithelium are notably polarized cells. For instance, Sertoli cell nuclei are found near the basement membrane. On the other hand, tight junction (TJ), basal ectoplasmic specialization (basal ES, a testis-specific actin-rich anchoring junction), gap junction (GJ) and desmosome that constitute the blood-testis barrier (BTB) are also located near the basement membrane. The BTB, in turn, divides the epithelium into the basal and the adluminal (apical) compartments. Within the epithelium, undifferentiated spermatogonia and preleptotene spermatocytes restrictively reside in the basal compartment whereas spermatocytes and post-meiotic spermatids reside in the adluminal compartment. Furthermore, the heads of elongating/elongated spermatids point toward the basement membrane with their elongating tails toward the tubule lumen. However, the involvement of polarity proteins in this unique cellular organization, in particular the underlying molecular mechanism(s) by which polarity proteins confer cellular polarity in the seminiferous epithelium is virtually unknown until recent years. Herein, we discuss latest findings regarding the role of different polarity protein complexes or modules and how these protein complexes are working in concert to modulate Sertoli cell and spermatid polarity. These findings also illustrate polarity proteins exert their effects through the actin-based cytoskeleton mediated by actin binding and regulatory proteins, which in turn modulate adhesion protein complexes at the cell-cell interface since TJ, basal ES and GJ utilize F-actin for attachment. We also propose a hypothetical model which illustrates the antagonistic effects of these polarity proteins. This in turn provides a unique mechanism to modulate junction remodeling in the testis to support germ cell transport across the epithelium in

  8. The definition of cross polarization

    DEFF Research Database (Denmark)

    Ludwig, Arthur

    1973-01-01

    There are at least three different definitions of cross polarization used in the literature. The alternative definitions are discussed with respect to several applications, and the definition which corresponds to one standard measurement practice is proposed as the best choice.......There are at least three different definitions of cross polarization used in the literature. The alternative definitions are discussed with respect to several applications, and the definition which corresponds to one standard measurement practice is proposed as the best choice....

  9. Polarized lepton-nucleon scattering

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, E.

    1994-02-01

    Deep inelastic polarized lepton-nucleon scattering is reviewed in three lectures. The first lecture covers the polarized deep inelastic scattering formalism and foundational theoretical work. The second lecture describes the nucleon spin structure function experiments that have been performed up through 1993. The third lecture discusses implication of the results and future experiments aimed at high-precision measurements of the nucleon spin structure functions.

  10. A rapid-screening approach to detect and quantify microplastics based on fluorescent tagging with Nile Red

    Science.gov (United States)

    Maes, Thomas; Jessop, Rebecca; Wellner, Nikolaus; Haupt, Karsten; Mayes, Andrew G.

    2017-03-01

    A new approach is presented for analysis of microplastics in environmental samples, based on selective fluorescent staining using Nile Red (NR), followed by density-based extraction and filtration. The dye adsorbs onto plastic surfaces and renders them fluorescent when irradiated with blue light. Fluorescence emission is detected using simple photography through an orange filter. Image-analysis allows fluorescent particles to be identified and counted. Magnified images can be recorded and tiled to cover the whole filter area, allowing particles down to a few micrometres to be detected. The solvatochromic nature of Nile Red also offers the possibility of plastic categorisation based on surface polarity characteristics of identified particles. This article details the development of this staining method and its initial cross-validation by comparison with infrared (IR) microscopy. Microplastics of different sizes could be detected and counted in marine sediment samples. The fluorescence staining identified the same particles as those found by scanning a filter area with IR-microscopy.

  11. Single-Photon Source for Quantum Information Based on Single Dye Molecule Fluorescence in Liquid Crystal Host

    Energy Technology Data Exchange (ETDEWEB)

    Lukishova, S.G.; Knox, R.P.; Freivald, P.; McNamara, A.; Boyd, R.W.; Stroud, Jr., C.R.; Schmid, A.W.; Marshall, K.L.

    2006-08-18

    This paper describes a new application for liquid crystals: quantum information technology. A deterministically polarized single-photon source that efficiently produces photons exhibiting antibunching is a pivotal hardware element in absolutely secure quantum communication. Planar-aligned nematic liquid crystal hosts deterministically align the single dye molecules which produce deterministically polarized single (antibunched) photons. In addition, 1-D photonic bandgap cholesteric liquid crystals will increase single-photon source efficiency. The experiments and challenges in the observation of deterministically polarized fluorescence from single dye molecules in planar-aligned glassy nematic-liquid-crystal oligomer as well as photon antibunching in glassy cholesteric oligomer are described for the first time.

  12. Bioelectric modulation of macrophage polarization

    Science.gov (United States)

    Li, Chunmei; Levin, Michael; Kaplan, David L.

    2016-02-01

    Macrophages play a critical role in regulating wound healing and tissue regeneration by changing their polarization state in response to local microenvironmental stimuli. The native roles of polarized macrophages encompass biomaterials and tissue remodeling needs, yet harnessing or directing the polarization response has been largely absent as a potential strategy to exploit in regenerative medicine to date. Recent data have revealed that specific alteration of cells’ resting potential (Vmem) is a powerful tool to direct proliferation and differentiation in a number of complex tissues, such as limb regeneration, craniofacial patterning and tumorigenesis. In this study, we explored the bioelectric modulation of macrophage polarization by targeting ATP sensitive potassium channels (KATP). Glibenclamide (KATP blocker) and pinacidil (KATP opener) treatment not only affect macrophage polarization, but also influence the phenotype of prepolarized macrophages. Furthermore, modulation of cell membrane electrical properties can fine-tune macrophage plasticity. Glibenclamide decreased the secretion and gene expression of selected M1 markers, while pinacidil augmented M1 markers. More interestingly, glibencalmide promoted macrophage alternative activation by enhancing certain M2 markers during M2 polarization. These findings suggest that control of bioelectric properties of macrophages could offer a promising approach to regulate macrophage phenotype as a useful tool in regenerative medicine.

  13. Enhancing colposcopy with polarized light.

    Science.gov (United States)

    Ferris, Daron G; Li, Wenjing; Gustafsson, Ulf; Lieberman, Richard W; Galdos, Oscar; Santos, Carlos

    2010-07-01

    To determine the potential utility of polarized light used during colposcopic examinations. Matched, polarized, and unpolarized colposcopic images and diagnostic annotations from 31 subjects receiving excisional treatment of cervical neoplasia were compared. Sensitivity, specificity, and mean Euclidean distances between the centroids of the gaussian ellipsoids for the different epithelial types were calculated for unpolarized and polarized images. The sensitivities of polarized colposcopic annotations for discriminating cervical intraepithelial neoplasia (CIN) 2 or higher were greater for all 3 acetowhite categories when compared with unpolarized annotations (58% [44/76] vs 45% [34/76], 68% [50/74] vs 59% [45/76], and 68% [49/72] vs 66% [50/76], respectively). The average percent differences in Euclidean distances between the epithelial types for unpolarized and polarized cervical images were as follows: CIN 2/3 versus CIN 1 = 33% (10/30, p =.03), CIN 2/3 versus columnar epithelium = 22% (p =.004), CIN 2/3 versus immature metaplasia = 29% (14/47, p =.11), and CIN 1 versus immature metaplasia = 27% (4.4/16, p =.16). Because of its ability to interrogate at a deeper plane and eliminate obscuring glare, polarized light colposcopy may enhance the evaluation and detection of cervical neoplasias.

  14. Polarization in heavy quark decays

    Energy Technology Data Exchange (ETDEWEB)

    Alimujiang, K.

    2006-07-01

    In this thesis I concentrate on the angular correlations in top quark decays and their next.to.leading order (NLO) QCD corrections. I also discuss the leading.order (LO) angular correlations in unpolarized and polarized hyperon decays. In the first part of the thesis I calculate the angular correlation between the top quark spin and the momentum of decay products in the rest frame decay of a polarized top quark into a charged Higgs boson and a bottom quark in Two-Higgs-Doublet-Models: t({up_arrow}) {yields} b + H{sup +}. I provide closed form formulae for the O({alpha}{sub s}) radiative corrections to the unpolarized and the polar correlation functions for m{sub b}{ne}0 and m{sub b}=0. In the second part I concentrate on the semileptonic rest frame decay of a polarized top quark into a bottom quark and a lepton pair: t({up_arrow}){yields}X{sub b}+l{sup +}+{nu}{sub l}. I present closed form expressions for the O({alpha}{sub s}) radiative corrections to the unpolarized part and the polar and azimuthal correlations for m{sub b}{ne}0 and m{sub b}=0. In the last part I turn to the angular distribution in semileptonic hyperon decays. Using the helicity method I derive complete formulas for the leading order joint angular decay distributions occurring in semileptonic hyperon decays including lepton mass and polarization effects. (orig.)

  15. Polarization in free electron lasers

    Energy Technology Data Exchange (ETDEWEB)

    Papadichev, V.A. [Lebedev Physical Institute, Moscow (Russian Federation)

    1995-12-31

    Polarization of electromagnetic radiation is required very often in numerous scientific and industrial applications: studying of crystals, molecules and intermolecular interaction high-temperature superconductivity, semiconductors and their transitions, polymers and liquid crystals. Using polarized radiation allows to obtain important data (otherwise inaccessible) in astrophysics, meteorology and oceanology. It is promising in chemistry and biology for selective influence on definite parts of molecules in chain synthesis reactions, precise control of various processes at cell and subcell levels, genetic engineering etc. Though polarization methods are well elaborated in optics, they can fail in far-infrared, vacuum-ultraviolet and X-ray regions because of lack of suitable non-absorbing materials and damaging of optical elements at high specific power levels. Therefore, it is of some interest to analyse polarization of untreated FEL radiation obtained with various types of undulators, with and without axial magnetic field. The polarization is studied using solutions for electron orbits in various cases: plane or helical undulator with or without axial magnetic field, two plane undulators, a combination of right- and left-handed helical undulators with equal periods, but different field amplitudes. Some examples of how a desired polarization (elliptical circular or linear) can be obtained or changed quickly, which is necessary in many experiments, are given.

  16. The Changing Polar Moon

    Science.gov (United States)

    Lucey, P. G.; Hurley, D.

    2015-12-01

    The Lunar Reconnaissance Orbiter (LRO) and LCROSS have provided an avalanche of new data regarding the lunar poles: LCROSS directly detected water vapor and other volatiles in its impact plume; LRO LAMP has detected surface frost using UV ratios; LEND has refined understanding of the distribution of hydrogen; LOLA and LAMP have showed that the spectral properties of permanently shadowed regions (PSR) are anomalous and may be due to unusual surface texture or altered space weathering; Diviner shows both where the coldest portions of the poles exist, and its quantitative results show where temperatures are low enough to preserve water ice at depth, well outside the PSRs. Yet while we are data rich, our understanding of the lunar poles is maddeningly poor. Our poverty of understanding is made even more baffling by the MESSENGER results from Mercury. At Mercury's poles the distribution of volatiles is dictated by temperature: where subsurface temperatures inferred from topography are consistent with long term preservation of water ice, radar anomalies indicating thick ice are present; where surface temperatures are consistent with preservation of surface frost, high reflectance anomalies indicating surface frost are revealed by laser reflectance. The distribution of water ice on Mercury is well understood. In contrast, temperature is only a weak indicator of the presence of volatiles at the lunar poles; there is little ability to predict the location and abundance of hydrogen or water. The difference may in the age of the volatile deposits on the two planets. Turn the clock forward a few billion years on Mercury and the deposits may appear more lunar. Surface lag deposits may have long ago succumbed to impact gardening, as has much of the shallow buried ice. Ice retained could be patchy, and confined to the coldest places that may tend to preserve it more effectively, even when finely comminuted. Lunar polar volatiles, a possible relic of an ancient, Mercury

  17. Brewster Angle Polarizing Beamsplitter Laser Damage Competition: P polarization

    Science.gov (United States)

    Stolz, Christopher J.; Runkel, Jeff

    2012-11-01

    Brewster angle plate polarizing beamsplitters play a critical role in splitting and combining beams within high power laser systems. A laser damage competition of polarizer beamsplitter coatings creates the opportunity to survey the current laser resistance these coatings within private industry, governmental institutions, and universities by a direct comparison of samples tested under identical conditions. The requirements of the coatings are a minimum transmission of 95% at "P" polarization and minimum reflection of 99% at "S" polarization at 1064 nm and 56.4 degrees angle of incidence. The choice of coating materials, design, and deposition method were left to the participant. Laser damage testing was performed according to the ISO 11254 standard utilizing a 1064 nm wavelength laser with a 10 ns pulse length operating at a repetition rate of 20 Hz. A double blind test assured sample and submitter anonymity so only a summary of the results are presented. In addition to the laser resistance results, details of cleaning methods, deposition processes, coating materials and layer count, and spectral results are also shared. Because of the large number of samples that were submitted, damage testing was conducted at "P" polarization only with "S" polarization damage testing reserved for next year on these submitted samples. Also the samples were only tested in the forward propagating direction; specifically samples were irradiated from air as the incident medium, through the thin film, and then through the substrate. In summary, a 6:1 difference existed for "P" polarization damage fluences amongst all of the competitors with the dominate variables that impacted the laser resistance being the deposition materials, deposition process, and cleaning method.

  18. Determination of metal ions by fluorescence anisotropy exhibits a broad dynamic range

    Science.gov (United States)

    Thompson, Richard B.; Maliwal, Badri P.; Fierke, Carol A.

    1998-05-01

    Recently, we have shown that metal ions free in solution may be determined at low levels by fluorescence anisotropy (polarization) measurements. Anisotropy measurements enjoy the advantages of wavelength ratiometric techniques for determining metal ions such as calcium, because anisotropy measurements are ratiometric as well. Furthermore, fluorescence anisotropy may be imaged in the microscope. An advantage of anisotropy not demonstrated for wavelength ratiometric approaches using indicators such as Fura-2 and Indo-1 is that under favorable circumstances anisotropy-based determinations exhibit a much broader dynamic range in metal ion concentration. Determinations of free Zn(II) in the picomolar range are demonstrated.

  19. Chlorophyll bleaching by UV-irradiation in vitro and in situ: Absorption and fluorescence studies

    Energy Technology Data Exchange (ETDEWEB)

    Zvezdanovic, Jelena [Faculty of Technology, University of Nish, Bulevar oslobodjenja 124, 16000 Leskovac (Serbia)], E-mail: jelite74@yahoo.com; Cvetic, Tijana [Faculty of Biology, University of Belgrade, Takovska 43, Belgrade 11000 (Serbia); Veljovic-Jovanovic, Sonja [Center for Multidisciplinary Studies, University of Belgrade, Kneza Viseslava la, Belgrade 11030 (Serbia); Markovic, Dejan [Faculty of Technology, University of Nish, Bulevar oslobodjenja 124, 16000 Leskovac (Serbia)], E-mail: dejan_markovic57@yahoo.com

    2009-01-15

    Chlorophyll bleaching by UV-irradiation has been studied by absorbance and fluorescence spectroscopy in extracts containing mixtures of photosynthetic pigments, in acetone and n-hexane solutions, and in aqueous thylakoid suspensions. Chlorophyll undergoes destruction (bleaching) accompanied by fluorescent transient formation obeying first-order kinetics. The bleaching is governed by UV-photon energy input, as well as by different chlorophyll molecular organizations in solvents of different polarities (in vitro), and in thylakoids (in situ). UV-C-induced bleaching of chlorophylls in thylakoids is probably caused by different mechanisms compared to UV-A- and UV-B-induced bleaching.

  20. Local mobility of polymer chain grafted onto polyethylene monitored by fluorescence depolarization

    Science.gov (United States)

    Tsuneda, Satoshi; Endo, Toshihiro; Saito, Kyoichi; Sugita, Kazuyuki; Horie, Kazuyuki; Yamashita, Takashi; Sugo, Takanobu

    1997-08-01

    The fluorescence depolarization method was used for investigating the local mobility of polymer chains grafted onto a porous polyethylene membrane. The real value of the rotational diffusion coefficient of a dansyl probe attached to the grafted polymer chain was obtained by using a correction method which eliminated the effect of multiple scattering on fluorescence anisotropy. The rotational mobility of the dansyl probe attached to the grafted polymer chain was sensitive to both degree of grafting and solvent polarity, which indicated that the conformation of the grafted polymer chain and the pore size of the base membrane strongly governed the dynamic parameters of the grafted polymer chain.