WorldWideScience

Sample records for brightly fluorescent carbon

  1. A route to brightly fluorescent carbon nanotubes for near-infrared imaging in mice

    OpenAIRE

    Welsher, Kevin; Liu, Zhuang; Sarah P Sherlock; Robinson, Joshua Tucker; Chen, Zhuo; Daranciang, Dan; Dai, Hongjie

    2009-01-01

    The near-infrared photoluminescence intrinsic to semiconducting single-walled carbon nanotubes is ideal for biological imaging owing to the low autofluorescence and deep tissue penetration in the near-infrared region beyond 1 µm. However, biocompatible single-walled carbon nanotubes with high quantum yield have been elusive. Here, we show that sonicating single-walled carbon nanotubes with sodium cholate, followed by surfactant exchange to form phospholipid–polyethylene glycol coated nanotube...

  2. Quantitative Brightness Analysis of Fluorescence Intensity Fluctuations in E. Coli.

    Directory of Open Access Journals (Sweden)

    Kwang-Ho Hur

    Full Text Available The brightness measured by fluorescence fluctuation spectroscopy specifies the average stoichiometry of a labeled protein in a sample. Here we extended brightness analysis, which has been mainly applied in eukaryotic cells, to prokaryotic cells with E. coli serving as a model system. The small size of the E. coli cell introduces unique challenges for applying brightness analysis that are addressed in this work. Photobleaching leads to a depletion of fluorophores and a reduction of the brightness of protein complexes. In addition, the E. coli cell and the point spread function of the instrument only partially overlap, which influences intensity fluctuations. To address these challenges we developed MSQ analysis, which is based on the mean Q-value of segmented photon count data, and combined it with the analysis of axial scans through the E. coli cell. The MSQ method recovers brightness, concentration, and diffusion time of soluble proteins in E. coli. We applied MSQ to measure the brightness of EGFP in E. coli and compared it to solution measurements. We further used MSQ analysis to determine the oligomeric state of nuclear transport factor 2 labeled with EGFP expressed in E. coli cells. The results obtained demonstrate the feasibility of quantifying the stoichiometry of proteins by brightness analysis in a prokaryotic cell.

  3. Wild Plum: novel particles of improved optical brightness and fluorescence.

    Science.gov (United States)

    Groathouse, Jordan; Barcena, Homar; Gustafson, Casey; Wilson, Mark V; Symonsbergen, David J; Lucas, Kerry A; Holmes, Andrea E

    2010-01-01

    A novel compound named Wild Plum fluoresces blue, and has been synthesized to camouflage skin imperfections, addressing the market demand for an anti-aging product. Wild Plum imparts optical brightness and fluorescence and can be used as an ingredient in cosmetic formulations. Skin appearance before and after application of Wild Plum compounds demonstrated an improved appearance of skin including a decreased number of wrinkles. When added to makeup, lotions, creams, and powders, Wild Plum conveys the glow of healthy youthful skin, replacing other costly or invasive alternatives such as cosmetic surgery. PMID:20716436

  4. Confidence intervals for concentration and brightness from fluorescence fluctuation measurements.

    Science.gov (United States)

    Pryse, Kenneth M; Rong, Xi; Whisler, Jordan A; McConnaughey, William B; Jiang, Yan-Fei; Melnykov, Artem V; Elson, Elliot L; Genin, Guy M

    2012-09-01

    The theory of photon count histogram (PCH) analysis describes the distribution of fluorescence fluctuation amplitudes due to populations of fluorophores diffusing through a focused laser beam and provides a rigorous framework through which the brightnesses and concentrations of the fluorophores can be determined. In practice, however, the brightnesses and concentrations of only a few components can be identified. Brightnesses and concentrations are determined by a nonlinear least-squares fit of a theoretical model to the experimental PCH derived from a record of fluorescence intensity fluctuations. The χ(2) hypersurface in the neighborhood of the optimum parameter set can have varying degrees of curvature, due to the intrinsic curvature of the model, the specific parameter values of the system under study, and the relative noise in the data. Because of this varying curvature, parameters estimated from the least-squares analysis have varying degrees of uncertainty associated with them. There are several methods for assigning confidence intervals to the parameters, but these methods have different efficacies for PCH data. Here, we evaluate several approaches to confidence interval estimation for PCH data, including asymptotic standard error, likelihood joint-confidence region, likelihood confidence intervals, skew-corrected and accelerated bootstrap (BCa), and Monte Carlo residual resampling methods. We study these with a model two-dimensional membrane system for simplicity, but the principles are applicable as well to fluorophores diffusing in three-dimensional solution. Using simulated fluorescence fluctuation data, we find the BCa method to be particularly well-suited for estimating confidence intervals in PCH analysis, and several other methods to be less so. Using the BCa method and additional simulated fluctuation data, we find that confidence intervals can be reduced dramatically for a specific non-Gaussian beam profile. PMID:23009839

  5. A Macrocyclic Fluorophore Dimer with Flexible Linkers: Bright Excimer Emission with a Long Fluorescence Lifetime.

    Science.gov (United States)

    Osaki, Hiroshi; Chou, Chih-Ming; Taki, Masayasu; Welke, Kai; Yokogawa, Daisuke; Irle, Stephan; Sato, Yoshikatsu; Higashiyama, Tetsuya; Saito, Shohei; Fukazawa, Aiko; Yamaguchi, Shigehiro

    2016-06-13

    Bright fluorescent molecules with long fluorescence lifetimes are important for the development of lifetime-based fluorescence imaging techniques. Herein, a molecular design is described for simultaneously attaining long fluorescence lifetime (τ) and high brightness (ΦF ×ɛ) in a system that features macrocyclic dimerization of fluorescent π-conjugated skeletons with flexible linkers. An alkylene-linked macrocyclic dimer of bis(thienylethynyl)anthracene was found to show excimer emission with a long fluorescence lifetime (τ≈19 ns) in solution, while maintaining high brightness. A comparison with various relevant derivatives revealed that the macrocyclic structure and the length of the alkylene chains play crucial roles in attaining these properties. In vitro time-gated imaging experiments were conducted as a proof-of-principle for the superiority of this macrocyclic fluorophore relative to the commercial fluorescent dye Alexa Fluor 488. PMID:27121201

  6. Fluorescent monomers: "bricks" that make a molecularly imprinted polymer "bright".

    Science.gov (United States)

    Wan, Wei; Wagner, Sabine; Rurack, Knut

    2016-03-01

    Molecularly imprinted polymers (MIPs) are potent and established recognition phases in separation and enrichment applications. Because of their robustness, versatility and format adaptability, they also constitute very promising sensing phases, especially when the active sensing element is directly integrated into the MIP. Fluorescent MIPs incorporating fluorescent monomers are perhaps the best developed and most successful approach here. This article reviews the state of the art in this field, discussing the pros and cons of the use of fluorescent dye and probe derivatives as such monomers, the different molecular interaction forces for template complexation, signalling modes and a variety of related approaches that have been realized over the years, including Förster resonance energy transfer processes, covalent imprinting, postmodification attachment of fluorescent units and conjugated polymers as MIPs; other measurement schemes and sensing chemistries that use MIPs and fluorescence interrogation to solve analytical problems (fluorescent competitive assays, fluorescent analytes, etc.) are not covered here. Throughout the article, photophysical processes are discussed to facilitate understanding of the effects that can occur when one is planning for a fluorescence response to happen in a constrained polymer matrix. The article concludes with a concise assessment of the suitability of the different formats for sensor realization. PMID:26613794

  7. Portable, Battery-Operated, Low-Cost, Bright Field and Fluorescence Microscope

    OpenAIRE

    Miller, Andrew R.; Davis, Gregory L.; Oden, Z. Maria; Razavi, Mohamad Reza; Fateh, Abolfazl; Ghazanfari, Morteza; Abdolrahimi, Farid; Poorazar, Shahin; Sakhaie, Fatemeh; Olsen, Randall J.; Bahrmand, Ahmad Reza; Pierce, Mark C.; Edward A. Graviss; Richards-Kortum, Rebecca

    2010-01-01

    This study describes the design and evaluation of a portable bright-field and fluorescence microscope that can be manufactured for $240 USD. The microscope uses a battery-operated LED-based flashlight as the light source and achieves a resolution of 0.8 µm at 1000× magnification in fluorescence mode. We tested the diagnostic capability of this new instrument to identify infections caused by the human pathogen, Mycobacterium tuberculosis. Sixty-four direct, decontaminated, and serially diluted...

  8. Observations of neutral carbon in the NGC 1977 bright rim

    Science.gov (United States)

    Wootten, A.; Phillips, T. G.; Beichman, C. A.; Frerking, M.

    1982-01-01

    Strong neutral carbon emission at 610 microns (492 GHz) has been detected from a bright-rimmed cloud abutting the H II region NGC 1977. The similarity of velocity and width between (C-13)O and C I lines suggests that both lines originate in the same region. A model for the density and temperature structure of the cloud, based on (C-13)O and (C-12)O observations, has been used to estimate the carbon abundance. The abundances of both C I and (C-13)O increase with depth into the cloud away from the rim. The carbon abundance reaches its peak value nearer the rim than does the (C-13)O abundance. This variation in the relative abundance distributions of CO and C I confirms the importance of photodissociation in the chemistry of molecular clouds, and of the C I line to studies of the interaction of hot stars with clouds.

  9. Gd(iii)-doped carbon dots as a dual fluorescent-MRI probe

    KAUST Repository

    Bourlinos, Athanasios B.

    2012-01-01

    We describe the synthesis of Gd(iii)-doped carbon dots as dual fluorescence-MRI probes for biomedical applications. The derived Gd(iii)-doped carbon dots show uniform particle size (3-4 nm) and gadolinium distribution and form stable dispersions in water. More importantly, they exhibit bright fluorescence, strong T1-weighted MRI contrast and low cytotoxicity. © The Royal Society of Chemistry 2012.

  10. Fluorescent carbon dot–molecular salt hydrogels

    OpenAIRE

    Cayuela, Angelina; Kennedy, Stuart R.; Soriano, Laura; Jones, Christopher D.; Valcárcel, M.; Steed, Jonathan W.

    2015-01-01

    The incorporation of functionalised carbon nanodots within a novel low molecular weight salt hydrogel derived from 5-aminosalicylic acid is reported. The carbon dots result in markedly enhanced gelation properties, while inclusion within the hydrophobic gel results in a dramatic fluorescence enhancement for the carbon nanomaterials. The resulting hybrid CD gels exhibit a useful sensor response for heavy metal ions, particularly Pb2+.

  11. Targeted imaging of EGFR overexpressed cancer cells by brightly fluorescent nanoparticles conjugated with cetuximab.

    Science.gov (United States)

    Gao, Meng; Su, Huifang; Lin, Gengwei; Li, Shiwu; Yu, Xingsu; Qin, Anjun; Zhao, Zujin; Zhang, Zhenfeng; Tang, Ben Zhong

    2016-08-11

    To improve the treatment efficiency and reduce side effects in cancer therapy, accurate diagnosis of cancer cell types at a molecular level is highly desirable. Fluorescent nanoparticles (NPs) are especially suitable for detecting molecular biomarkers of cancer with advantages of superior brightness, easy decoration and high resolution. However, the conventional organic fluorophores, conjugated polymers, and inorganic quantum dots suffer from the drawbacks of aggregation-caused quenching (ACQ), low photostability, and heavy metal toxicity, respectively, which severely restrict their applications in NPs-based fluorescence imaging. To overcome these limitations, herein, we have developed fluorescent nanoparticles based on a t-BuPITBT-TPE fluorophore derived from aggregation-induced emission (AIE)-active tetraphenylethene. Through encapsulating t-BuPITBT-TPE within biocompatible DSPE-PEG and further decorating with a monoclonal antibody cetuximab (C225), the obtained t-BuPITBT-TPE-C225 NPs can be used for targeted imaging of non-small cell lung cancer cells with an overexpressed epidermal growth factor receptor (EGFR). The specific targeting ability of t-BuPITBT-TPE-C225 NPs has been well verified by confocal microscopy and flow cytometry experiments. The t-BuPITBT-TPE-C225 NPs have shown significant advantages in terms of highly efficient red emission, good bio-compatibility, and excellent photostability. This work provides a promising method for precise diagnosis of cancer cells by antibody-functionalized fluorescent NPs with high brightness. PMID:27468980

  12. Very bright orange fluorescent plants: endoplasmic reticulum targeting of orange fluorescent proteins as visual reporters in transgenic plants

    Directory of Open Access Journals (Sweden)

    Mann David GJ

    2012-05-01

    Full Text Available Abstract Background The expression of fluorescent protein (FP genes as real-time visual markers, both transiently and stably, has revolutionized plant biotechnology. A palette of colors of FPs is now available for use, but the diversity has generally been underutilized in plant biotechnology. Because of the green and far-red autofluorescent properties of many plant tissues and the FPs themselves, red and orange FPs (RFPs, and OFPs, respectfully appear to be the colors with maximum utility in plant biotechnology. Within the color palette OFPs have emerged as the brightest FP markers in the visible spectra. This study compares several native, near-native and modified OFPs for their “brightness” and fluorescence, therefore, their usability as marker genes in transgenic plant tissues. Results The OFPs DsRed2, tdTomato, mOrange and pporRFP were all expressed under the control of the CaMV 35S promoter in agroinfiltration-mediated transient assays in Nicotiana benthamiana. Each of these, as well as endoplasmic reticulum (ER-targeted versions, were stably expressed in transgenic Nicotiana tabacum and Arabidopsis thaliana. Congruent results were observed between transient and stable assays. Our results demonstrated that there are several adequate OFP genes available for plant transformation, including the new pporRFP, an unaltered tetramer from the hard coral Porites porites. When the tandem dimer tdTomato and the monomeric mOrange were targeted to the ER, dramatic, ca. 3-fold, increase in plant fluorescence was observed. Conclusions From our empirical data, and a search of the literature, it appears that tdTomato-ER and mOrange-ER are the two highest fluorescing FPs available as reporters for transgenic plants. The pporRFP is a brightly fluorescing tetramer, but all tetramer FPs are far less bright than the ER-targeted monomers we report here.

  13. Augmented microscopy: real-time overlay of bright-field and near-infrared fluorescence images

    Science.gov (United States)

    Watson, Jeffrey R.; Gainer, Christian F.; Martirosyan, Nikolay; Skoch, Jesse; Lemole, G. Michael, Jr.; Anton, Rein; Romanowski, Marek

    2015-10-01

    Intraoperative applications of near-infrared (NIR) fluorescent contrast agents can be aided by instrumentation capable of merging the view of surgical field with that of NIR fluorescence. We demonstrate augmented microscopy, an intraoperative imaging technique in which bright-field (real) and electronically processed NIR fluorescence (synthetic) images are merged within the optical path of a stereomicroscope. Under luminance of 100,000 lx, representing typical illumination of the surgical field, the augmented microscope detects 189 nM concentration of indocyanine green and produces a composite of the real and synthetic images within the eyepiece of the microscope at 20 fps. Augmentation described here can be implemented as an add-on module to visualize NIR contrast agents, laser beams, or various types of electronic data within the surgical microscopes commonly used in neurosurgical, cerebrovascular, otolaryngological, and ophthalmic procedures.

  14. Augmented microscopy: real-time overlay of bright-field and near-infrared fluorescence images.

    Science.gov (United States)

    Watson, Jeffrey R; Gainer, Christian F; Martirosyan, Nikolay; Skoch, Jesse; Lemole, G Michael; Anton, Rein; Romanowski, Marek

    2015-10-01

    Intraoperative applications of near-infrared (NIR) fluorescent contrast agents can be aided by instrumentation capable of merging the view of surgical field with that of NIR fluorescence. We demonstrate augmented microscopy, an intraoperative imaging technique in which bright-field (real) and electronically processed NIR fluorescence (synthetic) images are merged within the optical path of a stereomicroscope. Under luminance of 100,000 lx, representing typical illumination of the surgical field, the augmented microscope detects 189 nM concentration of indocyanine green and produces a composite of the real and synthetic images within the eyepiece of the microscope at 20 fps. Augmentation described here can be implemented as an add-on module to visualize NIR contrast agents, laser beams, or various types of electronic data within the surgical microscopes commonly used in neurosurgical, cerebrovascular, otolaryngological, and ophthalmic procedures. PMID:26440760

  15. Portable, battery-operated, low-cost, bright field and fluorescence microscope.

    Science.gov (United States)

    Miller, Andrew R; Davis, Gregory L; Oden, Z Maria; Razavi, Mohamad Reza; Fateh, Abolfazl; Ghazanfari, Morteza; Abdolrahimi, Farid; Poorazar, Shahin; Sakhaie, Fatemeh; Olsen, Randall J; Bahrmand, Ahmad Reza; Pierce, Mark C; Graviss, Edward A; Richards-Kortum, Rebecca

    2010-01-01

    This study describes the design and evaluation of a portable bright-field and fluorescence microscope that can be manufactured for $240 USD. The microscope uses a battery-operated LED-based flashlight as the light source and achieves a resolution of 0.8 microm at 1000x magnification in fluorescence mode. We tested the diagnostic capability of this new instrument to identify infections caused by the human pathogen, Mycobacterium tuberculosis. Sixty-four direct, decontaminated, and serially diluted smears were prepared from sputa obtained from 19 patients suspected to have M. tuberculosis infection. Slides were stained with auramine orange and evaluated as being positive or negative for M. tuberculosis with both the new portable fluorescence microscope and a laboratory grade fluorescence microscope. Concordant results were obtained in 98.4% of cases. This highly portable, low cost, fluorescence microscope may be a useful diagnostic tool to expand the availability of M. tuberculosis testing at the point-of-care in low resource settings. PMID:20694194

  16. Portable, battery-operated, low-cost, bright field and fluorescence microscope.

    Directory of Open Access Journals (Sweden)

    Andrew R Miller

    Full Text Available This study describes the design and evaluation of a portable bright-field and fluorescence microscope that can be manufactured for $240 USD. The microscope uses a battery-operated LED-based flashlight as the light source and achieves a resolution of 0.8 microm at 1000x magnification in fluorescence mode. We tested the diagnostic capability of this new instrument to identify infections caused by the human pathogen, Mycobacterium tuberculosis. Sixty-four direct, decontaminated, and serially diluted smears were prepared from sputa obtained from 19 patients suspected to have M. tuberculosis infection. Slides were stained with auramine orange and evaluated as being positive or negative for M. tuberculosis with both the new portable fluorescence microscope and a laboratory grade fluorescence microscope. Concordant results were obtained in 98.4% of cases. This highly portable, low cost, fluorescence microscope may be a useful diagnostic tool to expand the availability of M. tuberculosis testing at the point-of-care in low resource settings.

  17. Ultra-fast bright field and fluorescence imaging of the dynamics of micrometer-sized objects

    Science.gov (United States)

    Chen, Xucai; Wang, Jianjun; Versluis, Michel; de Jong, Nico; Villanueva, Flordeliza S.

    2013-06-01

    High speed imaging has application in a wide area of industry and scientific research. In medical research, high speed imaging has the potential to reveal insight into mechanisms of action of various therapeutic interventions. Examples include ultrasound assisted thrombolysis, drug delivery, and gene therapy. Visual observation of the ultrasound, microbubble, and biological cell interaction may help the understanding of the dynamic behavior of microbubbles and may eventually lead to better design of such delivery systems. We present the development of a high speed bright field and fluorescence imaging system that incorporates external mechanical waves such as ultrasound. Through collaborative design and contract manufacturing, a high speed imaging system has been successfully developed at the University of Pittsburgh Medical Center. We named the system "UPMC Cam," to refer to the integrated imaging system that includes the multi-frame camera and its unique software control, the customized modular microscope, the customized laser delivery system, its auxiliary ultrasound generator, and the combined ultrasound and optical imaging chamber for in vitro and in vivo observations. This system is capable of imaging microscopic bright field and fluorescence movies at 25 × 106 frames per second for 128 frames, with a frame size of 920 × 616 pixels. Example images of microbubble under ultrasound are shown to demonstrate the potential application of the system.

  18. Aharonov-Bohm effects on bright and dark excitons in carbon nanotubes

    International Nuclear Information System (INIS)

    A short-range part of the Coulomb interaction causes splitting and shift of excitons due to exchange interaction and mixing between different valleys in semiconducting carbon nanotubes. In the absence of a magnetic flux only a single exciton is optically active (bright) and all others are inactive (dark). Two bright excitons appear in the presence of an Aharonov- Bohm magnetic flux

  19. Bright and photostable cyanine-styryl chromophores with green and red fluorescence colour for DNA staining

    Science.gov (United States)

    Bohländer, Peggy R.; Wagenknecht, Hans-Achim

    2015-12-01

    The synthesis and optical characterisation of a series of green- and red-emitting cyanine and cyanine-styryl dyes is presented that were developed based on the cyanine-indole-quinolinium and based on the thiazole red type structure. For the green emitting fluorophores the quinolinium part was replaced by a pyridinium group. The bridge to the indole group was attached either to the 2-position or to the 4-position of the pyridinium moiety. For the red-emitting dyes the connection to the indole moiety is at the 4-position of the quinolinium part. In each set of dyes a methyl group at the indole-NH and/or a phenyl group at the 2-position of the indole part were introduced to tune the optical properties and photostability. Additionally, two dyes were modified with a cyano group to tune the photophysical properties and to enhance the photostabilities. The developed dyes show good photostabilities and bright green or red fluorescence intensities in the presence of DNA. Thus, these dyes represent important and promising candidates for fluorescent molecular imaging of nucleic acids inside living cells.

  20. Carbon abundances and isotope ratios in 70 bright M giants

    International Nuclear Information System (INIS)

    Approximate carbon abundances and 12C/13C isotope ratios are obtained for 70 M giant stars from intermediate-resolution spectrophotometry of the CO bands near 2.3 μm. A low mean carbon abundance ([C/H]=-0.64±0.29) is obtained, suggesting that standard mixing is insufficient to explain atmospheric abundances in M giants. HR 8795 appears to be exceptionally carbon deficient, and is worthy of further study as a possible weak G-band star descendant. (author)

  1. Carbon abundances and isotope ratios in 70 bright M giants

    Energy Technology Data Exchange (ETDEWEB)

    Lazaro, C. (Inst. de Astrofisica de Canarias, Tenerife (Spain)); Lynas-Gray, A.E. (University Coll., London (UK). Dept. of Physics and Astronomy); Clegg, R.E.S. (Royal Greenwich Observatory, Cambridge (UK)); Mountain, C.M.; Zadrozny, A. (Imperial Coll. of Science and Technology, London (UK))

    1991-03-01

    Approximate carbon abundances and {sup 12}C/{sup 13}C isotope ratios are obtained for 70 M giant stars from intermediate-resolution spectrophotometry of the CO bands near 2.3 {mu}m. A low mean carbon abundance ((C/H)=-0.64+-0.29) is obtained, suggesting that standard mixing is insufficient to explain atmospheric abundances in M giants. HR 8795 appears to be exceptionally carbon deficient, and is worthy of further study as a possible weak G-band star descendant. (author).

  2. Green Synthesis of Fluorescent Carbon Dots for Selective Detection of Tartrazine in Food Samples.

    Science.gov (United States)

    Xu, Hua; Yang, Xiupei; Li, Gu; Zhao, Chuan; Liao, Xiangjun

    2015-08-01

    A simple, economical, and green method for the preparation of water-soluble, high-fluorescent carbon quantum dots (C-dots) has been developed via hydrothermal process using aloe as a carbon source. The synthesized C-dots were characterized by atomic force microscope (AFM), transmission electron microscopy (TEM), fluorescence spectrophotometer, UV-vis absorption spectra as well as Fourier transform infrared spectroscopy (FTIR). The results reveal that the as-prepared C-dots were spherical shape with an average diameter of 5 nm and emit bright yellow photoluminescence (PL) with a quantum yield of approximately 10.37%. The surface of the C-dots was rich in hydroxyl groups and presented various merits including high fluorescent quantum yield, excellent photostability, low toxicity and satisfactory solubility. Additionally, we found that one of the widely used synthetic food colorants, tartrazine, could result in a strong fluorescence quenching of the C-dots through a static quenching process. The decrease of fluorescence intensity made it possible to determine tartrazine in the linear range extending from 0.25 to 32.50 μM, This observation was further successfully applied for the determination of tartrazine in food samples collected from local markets, suggesting its great potential toward food routine analysis. Results from our study may shed light on the production of fluorescent and biocompatible nanocarbons due to our simple and environmental benign strategy to synthesize C-dots in which aloe was used as a carbon source. PMID:26154603

  3. Bright carbonate deposits as evidence of aqueous alteration on (1) Ceres

    Science.gov (United States)

    de Sanctis, M. C.; Raponi, A.; Ammannito, E.; Ciarniello, M.; Toplis, M. J.; McSween, H. Y.; Castillo-Rogez, J. C.; Ehlmann, B. L.; Carrozzo, F. G.; Marchi, S.; Tosi, F.; Zambon, F.; Capaccioni, F.; Capria, M. T.; Fonte, S.; Formisano, M.; Frigeri, A.; Giardino, M.; Longobardo, A.; Magni, G.; Palomba, E.; McFadden, L. A.; Pieters, C. M.; Jaumann, R.; Schenk, P.; Mugnuolo, R.; Raymond, C. A.; Russell, C. T.

    2016-08-01

    The typically dark surface of the dwarf planet Ceres is punctuated by areas of much higher albedo, most prominently in the Occator crater. These small bright areas have been tentatively interpreted as containing a large amount of hydrated magnesium sulfate, in contrast to the average surface, which is a mixture of low-albedo materials and magnesium phyllosilicates, ammoniated phyllosilicates and carbonates. Here we report high spatial and spectral resolution near-infrared observations of the bright areas in the Occator crater on Ceres. Spectra of these bright areas are consistent with a large amount of sodium carbonate, constituting the most concentrated known extraterrestrial occurrence of carbonate on kilometre-wide scales in the Solar System. The carbonates are mixed with a dark component and small amounts of phyllosilicates, as well as ammonium carbonate or ammonium chloride. Some of these compounds have also been detected in the plume of Saturn’s sixth-largest moon Enceladus. The compounds are endogenous and we propose that they are the solid residue of crystallization of brines and entrained altered solids that reached the surface from below. The heat source may have been transient (triggered by impact heating). Alternatively, internal temperatures may be above the eutectic temperature of subsurface brines, in which case fluids may exist at depth on Ceres today.

  4. Controlling carbon nanodot fluorescence for optical biosensing.

    Science.gov (United States)

    Buiculescu, Raluca; Stefanakis, Dimitrios; Androulidaki, Maria; Ghanotakis, Demetrios; Chaniotakis, Nikos A

    2016-06-20

    In this work we report on the optical properties of specific synthetic carbon nano-dots (CDs) and their suitability for the development of optical biosensors. We examine the photoluminescence behavior of these CDs under different conditions, in their native form, as well as when conjugated to the catalytic protein glucose oxidase (GOx) for the construction of optical glucose biosensors. The effect of pH and hydrogen peroxide on the observed spectra is examined as the basis for the biosensor development. The CDs examined here have inherent surface amino functional groups which allow for easy conjugation to biomolecules via EDC-NHS, providing a well defined platform for biosensing applications. We conclude that the well controlled, stable, and highly efficient fluorescence behavior of the CDs in solution or in conjugate, provides the grounds for this class of materials to be used in a variety of arrangements for the development of optical and optoelectrochemical detection systems. PMID:27170233

  5. Dependence of fluorescent protein brightness on protein concentration in solution and enhancement of it

    Science.gov (United States)

    Morikawa, Takamitsu J.; Fujita, Hideaki; Kitamura, Akira; Horio, Takashi; Yamamoto, Johtaro; Kinjo, Masataka; Sasaki, Akira; Machiyama, Hiroaki; Yoshizawa, Keiko; Ichimura, Taro; Imada, Katsumi; Nagai, Takeharu; Watanabe, Tomonobu M.

    2016-01-01

    Fluorescent proteins have been widely used in biology because of their compatibility and varied applications in living specimens. Fluorescent proteins are often undesirably sensitive to intracellular conditions such as pH and ion concentration, generating considerable issues at times. However, harnessing these intrinsic sensitivities can help develop functional probes. In this study, we found that the fluorescence of yellow fluorescent protein (YFP) depends on the protein concentration in the solution and that this dependence can be enhanced by adding a glycine residue in to the YFP; we applied this finding to construct an intracellular protein-crowding sensor. A Förster resonance energy transfer (FRET) pair, involving a cyan fluorescent protein (CFP) insensitive to protein concentration and a glycine-inserted YFP, works as a genetically encoded probe to evaluate intracellular crowding. By measuring the fluorescence of the present FRET probe, we were able to detect dynamic changes in protein crowding in living cells. PMID:26956628

  6. Fluorescence labeling of carbon nanotubes and visualization of a nanotube-protein hybrid under fluorescence microscope.

    Science.gov (United States)

    Yoshimura, Shige H; Khan, Shahbaz; Maruyama, Hiroyuki; Nakayama, Yoshikazu; Takeyasu, Kunio

    2011-04-11

    Biological applications of carbon nanotubes have been hampered by the inability to visualize them using conventional optical microscope, which is the most common tool for the observation and measurement of biological processes. Recently, a number of fluorescence labeling methods for biomolecules and various fluorescence probes have been developed and widely utilized in biological fields. Therefore, labeling carbon nanotubes with such fluorophores under physiological conditions will be highly useful in their biological applications. In this Article, we present a method to fluorescently label nanotubes by combining a detergent and a fluorophore commonly used in biological experiments. Fluorophores carrying an amino group (Texas Red hydrazide or BODIPY FL-hydrazide) were covalently attached to the hydroxyl groups of Tween 20 using carbonyldiimidazole. Fluorescence microscopy demonstrated that nanotubes were efficiently solubilized and labeled by this fluorescently labeled detergent. By using this technique, we also demonstrated multicolor fluorescence imaging of a nanotube-protein hybrid. PMID:21395219

  7. Highly surface functionalized carbon nano-onions for bright light bioimaging

    Science.gov (United States)

    Frasconi, Marco; Maffeis, Viviana; Bartelmess, Juergen; Echegoyen, Luis; Giordani, Silvia

    2015-12-01

    Carbon-based nanomaterials functionalized with fluorescent and water-soluble groups have emerged as platforms for biological imaging because of their low toxicity and ability to be internalized by cells. The development of imaging probes based on carbon nanomaterials for biomedical studies requires the understanding of their biological response as well as the efficient and safety exposition of the nanomaterial to the cell compartment where it is designed to operate. Here, we present a fluorescent probe based on surface functionalized carbon nano-onions (CNOs) for biological imaging. The modification of CNOs by chemical oxidation of the defects on the outer shell of these carbon nanoparticles results in an extensive surface functionalization with carboxyl groups. We have obtained fluorescently labelled CNOs by a reaction involving the amide bond formation between fluoresceinamine and the carboxylic acids groups on the surface of the CNOs. The functionalized CNOs display high emission properties and dispersability in water due to the presence of high surface coverage of carboxylic acid groups that translate in an efficient fluorescent probe for in vitro imaging of HeLa cells, without significant cytotoxicity. The resulting nanomaterial represents a promising platform for biological imaging applications due to the high dispersability in water, its efficient internalization by cancer cells and localization in specific cell compartments.

  8. Fluorescent Carbon Nanoparticles in Medicine for Cancer Therapy

    OpenAIRE

    Kumar, Vinit; Toffoli, Giuseppe; Rizzolio, Flavio

    2013-01-01

    Nanotechnology provides exciting opportunities for the development of novel, clinically relevant diagnostic and therapeutic multifunctional systems. Fluorescent carbon nanoparticles (CNPs) due to their intrinsic fluorescence and high biocompatibility are among the best candidates. As innovative nanomaterials, CNPs could be utilized both as nontoxic drug delivery system and bioimaging. We foresee a great future for CNPs in cancer diagnostic and therapy.

  9. High brightness field emission from printed carbon nanotubes in an S-band microwave gun

    Science.gov (United States)

    Wang, Qilong; Li, Xiangkun; Di, Yusong; Yu, Cairu; Zhang, Xiaobing; Li, Ming; Lei, Wei

    2016-02-01

    Printed carbon nanotubes (CNTs) were applied as cold cathode and placed into an S-band microwave gun operating at 2856 MHz with the pulse duration of 2.8 μs. High brightness field emission was demonstrated and the current density achieves the value more than 4.2 A/cm2. The emittance of field emission beam is calculated to be nearly 21 μm based on the beam profile of emission electrons monitored via yttrium aluminum garnet screen. The infrared image of printed CNTs confirms that the emitters in the center contributed more electrons and the heat generated during the large current density field emission. The results in the paper imply that randomly distributed printed CNTs have the potential to be applied as the high brightness electron sources for free electron lasers.

  10. J-aggregation of a sulfur-substituted naphthalenediimide (NDI) with remarkably bright fluorescence.

    Science.gov (United States)

    Kar, Haridas; Ghosh, Suhrit

    2016-07-01

    This communication reveals the H-bonding driven supramolecular assembly of a sulfur-substituted naphthalenediimide leading to the formation of very strong (Tg > 90 °C) organogel in aliphatic hydrocarbons. Mechanistic investigation reveals nucleation-elongation pathway for self-assembly. Photophysical studies show explicit features of classical J-aggregation which reduces the non-radiative fluorescence rate constant considerably and thus results in a remarkable fluorescence enhancement (ΦPL increases from 1% to 30%) which is unprecedented in the entire NDI literature. PMID:27346798

  11. Simultaneous fluorescence and high-resolution bright-field imaging with aberration correction over a wide field-of-view with Fourier ptychographic microscopy (FPM) (Conference Presentation)

    Science.gov (United States)

    Chung, Jaebum; Kim, Jinho; Ou, Xiaoze; Horstmeyer, Roarke; Yang, Changhuei

    2016-03-01

    We present a method to acquire both fluorescence and high-resolution bright-field images with correction for the spatially varying aberrations over a microscope's wide field-of-view (FOV). First, the procedure applies Fourier ptychographic microscopy (FPM) to retrieve the amplitude and phase of a sample, at a resolution that significantly exceeds the cutoff frequency of the microscope objective lens. At the same time, FPM algorithm is able to leverage on the redundancy within the set of acquired FPM bright-field images to estimate the microscope aberrations, which usually deteriorate in regions further away from the FOV's center. Second, the procedure acquires a raw wide-FOV fluorescence image within the same setup. Lack of moving parts allows us to use the FPM-estimated aberration map to computationally correct for the aberrations in the fluorescence image through deconvolution. Overlaying the aberration-corrected fluorescence image on top of the high-resolution bright-field image can be done with accurate spatial correspondence. This can provide means to identifying fluorescent regions of interest within the context of the sample's bright-field information. An experimental demonstration successfully improves the bright-field resolution of fixed, stained and fluorescently tagged HeLa cells by a factor of 4.9, and reduces the error caused by aberrations in a fluorescence image by 31%, over a field of view of 6.2 mm by 9.3 mm. For optimal deconvolution, we show the fluorescence image needs to have a signal-to-noise ratio of ~18.

  12. Self-Assembled Gold Nanoclusters for Bright Fluorescence Imaging and Enhanced Drug Delivery.

    Science.gov (United States)

    Yahia-Ammar, Akram; Sierra, Daniel; Mérola, Fabienne; Hildebrandt, Niko; Le Guével, Xavier

    2016-02-23

    Nanoparticles combining enhanced cellular drug delivery with efficient fluorescence detection are important tools for the development of theranostic agents. Here, we demonstrate this concept by a simple, fast, and robust protocol of cationic polymer-mediated gold nanocluster (Au NCs) self-assembly into nanoparticles (NPs) of ca. 120 nm diameter. An extensive characterization of the monodisperse and positively charged NPs revealed pH-dependent swelling properties, strong fluorescence enhancement, and excellent colloidal and photostability in water, buffer, and culture medium. The versatility of the preparation is demonstrated by using different Au NC surface ligands and cationic polymers. Steady-state and time-resolved fluorescence measurements give insight into the aggregation-induced emission phenomenon (AIE) by tuning the Au NC interactions in the self-assembled nanoparticles using the pH-dependent swelling. In vitro studies in human monocytic cells indicate strongly enhanced uptake of the NPs compared to free Au NCs in endocytic compartments. The NPs keep their assembly structure with quite low cytotoxicity up to 500 μg Au/mL. Enhanced drug delivery is demonstrated by loading peptides or antibodies in the NPs using a one-pot synthesis. Fluorescence microscopy and flow cytometry confirmed intracellular colocalization of the biomolecules and the NP carriers with a respective 1.7-fold and 6.5-fold enhanced cellular uptake of peptides and antibodies compared to the free biomolecules. PMID:26845515

  13. Selective detection of Escherichia coli DNA using fluorescent carbon spindles.

    Science.gov (United States)

    Roy, Anurag; Chatterjee, Sabyasachi; Pramanik, Srikrishna; Devi, Parukuttyamma Sujatha; Suresh Kumar, Gopinatha

    2016-04-28

    We investigate the interaction of hydrophilic blue emitting carbon spindles with various deoxyribonucleic acids (DNA) having different base pair compositions, such as Herring testes (HT), calf thymus (CT), Escherichia coli (EC) and Micrococcus lysodeikticus (ML) DNA, to understand the mode of interaction. Interestingly, the fluorescent carbon spindles selectively interacted with E. coli DNA resulting in enhanced fluorescence of the former. Interaction of the same carbon with other DNAs exhibited insignificant changes in fluorescence. In addition, in the presence of EC DNA, the D band in the Raman spectrum attributed to the defect state completely disappeared, resulting in enhanced crystallinity. Microscopy images confirmed the wrapping of DNA on the carbon spindles leading to the assembly of spindles in the form of flowers. Dissociation of double-stranded DNA occurred upon interaction with carbon spindles, resulting in selective E. coli DNA interaction. The carbon spindles also exhibited a similar fluorescence enhancement upon treating with E. coli bacteria. These results confirm the possibility of E. coli detection in water and other liquid foods using such fluorescent carbon. PMID:27081680

  14. Imaging magnetic scalar potentials by laser-induced fluorescence from bright and dark atoms

    Science.gov (United States)

    Fescenko, I.; Weis, A.

    2014-06-01

    We present a spectroscopic method for mapping two-dimensional distributions of magnetic field strengths (magnetic scalar potential lines) using charge-coupled device (CCD) recordings of the fluorescence patterns emitted by spin-polarized Cs vapour in a buffer gas exposed to inhomogeneous magnetic fields. The method relies on the position-selective destruction of spin polarization by magnetic resonances induced by multi-component oscillating magnetic fields, such that magnetic potential lines can be directly detected by the CCD camera. We also present a generic algebraic model allowing for the calculation of the fluorescence patterns and find excellent agreement with the experimental observations for three distinct inhomogeneous field topologies. The spatial resolution obtained with these proof-of-principle experiments is of the order of 1 mm. A substantial increase of spatial and magnetic field resolution is expected by deploying the method in a magnetically shielded environment.

  15. Imaging magnetic scalar potentials by laser-induced fluorescence from bright and dark atoms

    CERN Document Server

    Fescenko, Ilja

    2014-01-01

    We present a spectroscopic method for mapping two-dimensional distributions of magnetic field strengths (magnetic scalar potential lines) using CCD recordings of the fluorescence patterns emitted by spin-polarized Cs vapor in a buffer gas exposed to inhomogeneous magnetic fields. The method relies on the position-selective destruction of spin polarization by magnetic resonances induced by multi-component oscillating magnetic fields, such that magnetic potential lines can directly be detected by the CCD camera. We also present a generic algebraic model allowing the calculation of the fluorescence patterns and find excellent agreement with the experimental observations for three distinct inhomogeneous field topologies. The spatial resolution obtained with these proof-of-principle experiments is on the order of 1 mm. A substantial increase of spatial and magnetic field resolution is expected by deploying the method in a magnetically shielded environment.

  16. Imaging magnetic scalar potentials by laser-induced fluorescence from bright and dark atoms

    OpenAIRE

    Fescenko, Ilja; Weis, Antoine

    2014-01-01

    We present a spectroscopic method for mapping two-dimensional distributions of magnetic field strengths (magnetic scalar potential lines) using charge-coupled device (CCD) recordings of the fluorescence patterns emitted by spin-polarized Cs vapour in a buffer gas exposed to inhomogeneous magnetic fields. The method relies on the position-selective destruction of spin polarization by magnetic resonances induced by multi-component oscillating magnetic fields, such that magnetic potential lines ...

  17. Comparison of thin-layer chromatography, spectrofluorimetry and bright greenish-yellow fluorescence test for aflatoxin detection in corn

    Directory of Open Access Journals (Sweden)

    Elisabete Yurie Sataque Ono

    2010-06-01

    Full Text Available In this study the bright greenish-yellow fluorescence test, widely used by the corn milling industry, was compared to the thin-layer chromatography (TLC and spectrofluorimetry methods for aflatoxin detection in 40 corn samples naturally contaminated by the Aspergillus section Flavi. According to the corn processing industry criteria, all the samples were adequate for human and animal consumption by the bright greenish-yellow fluorescence test, but TLC and spectrofluorimetry analysis detected aflatoxins above the maximum tolerated limit (20 µg/kg in 7 and 8 samples, respectively. Aflatoxins were detected in 16 (40% corn samples by TLC, with levels ranging from 4.0 to 54.0 µg/kg (mean 19.97 ± 15.97 µg/kg, and in 25 (62.5% samples by spectrofluorimetry, with levels ranging from 1.0 to 58.66 µg/kg (mean 17.14 ± 17.81 µg/kg. The results indicated a good correlation (ρ = 0.97 between TLC and spectrofluorimetry for aflatoxin determination in naturally contaminated corn. The bright greenish-yellow fluorescence test was simple and quick, but it showed 20% false-negative results, suggesting its use only as screening method for detecting the suspected lots of grains that should be tested further for aflatoxin by more sensitive methods.Neste trabalho a contagem de fluorescência luminosa amarelo-esverdeada, amplamente utilizada pela indústria de processamento de milho, foi comparada à cromatografia em camada delgada (CCD e espectrofluorimetria para detecção de aflatoxinas em 40 amostras de milho naturalmente contaminadas por Aspergillus section Flavi. De acordo com os critérios da indústria processadora de milho, todas as amostras estavam adequadas para o consumo humano e animal pela contagem de fluorescência luminosa amarelo-esverdeada (CFLAE, porém as análises por CCD e espectrofluorimetria detectaram aflatoxinas acima do limite máximo tolerado (20 µg/kg em 7 e 8 amostras, respectivamente. As aflatoxinas foram detectadas em 16 (40

  18. A Novel Reporter Rat Strain That Conditionally Expresses the Bright Red Fluorescent Protein tdTomato.

    Directory of Open Access Journals (Sweden)

    Hiroyuki Igarashi

    Full Text Available Despite the strength of the Cre/loxP recombination system in animal models, its application in rats trails that in mice because of the lack of relevant reporter strains. Here, we generated a floxed STOP tdTomato rat that conditionally expresses a red fluorescent protein variant (tdTomato in the presence of exogenous Cre recombinase. The tdTomato signal vividly visualizes neurons including their projection fibers and spines without any histological enhancement. In addition, a transgenic rat line (FLAME that ubiquitously expresses tdTomato was successfully established by injecting intracytoplasmic Cre mRNA into fertilized ova. Our rat reporter system will facilitate connectome studies as well as the visualization of the fine structures of genetically identified cells for long periods both in vivo and ex vivo. Furthermore, FLAME is an ideal model for organ transplantation research owing to improved traceability of cells/tissues.

  19. A Novel Reporter Rat Strain That Conditionally Expresses the Bright Red Fluorescent Protein tdTomato.

    Science.gov (United States)

    Igarashi, Hiroyuki; Koizumi, Kyo; Kaneko, Ryosuke; Ikeda, Keiko; Egawa, Ryo; Yanagawa, Yuchio; Muramatsu, Shin-Ichi; Onimaru, Hiroshi; Ishizuka, Toru; Yawo, Hiromu

    2016-01-01

    Despite the strength of the Cre/loxP recombination system in animal models, its application in rats trails that in mice because of the lack of relevant reporter strains. Here, we generated a floxed STOP tdTomato rat that conditionally expresses a red fluorescent protein variant (tdTomato) in the presence of exogenous Cre recombinase. The tdTomato signal vividly visualizes neurons including their projection fibers and spines without any histological enhancement. In addition, a transgenic rat line (FLAME) that ubiquitously expresses tdTomato was successfully established by injecting intracytoplasmic Cre mRNA into fertilized ova. Our rat reporter system will facilitate connectome studies as well as the visualization of the fine structures of genetically identified cells for long periods both in vivo and ex vivo. Furthermore, FLAME is an ideal model for organ transplantation research owing to improved traceability of cells/tissues. PMID:27195805

  20. Red Fluorescent Carbon Nanoparticle-Based Cell Imaging Probe.

    Science.gov (United States)

    Ali, Haydar; Bhunia, Susanta Kumar; Dalal, Chumki; Jana, Nikhil R

    2016-04-13

    Fluorescent carbon nanoparticle-based probes with tunable visible emission are biocompatible, environment friendly and most suitable for various biomedical applications. However, synthesis of red fluorescent carbon nanoparticles and their transformation into functional nanoparticles are very challenging. Here we report red fluorescent carbon nanoparticle-based nanobioconjugates of carbon nanoparticles are synthesized via high temperature colloid-chemical approach and transformed into water-soluble functional nanoparticles via coating with amphiphilic polymer followed by covalent linking with desired biomolecules. Following this approach, carbon nanoparticles are functionalized with polyethylene glycol, primary amine, glucose, arginine, histidine, biotin and folic acid. These functional nanoparticles can be excited with blue/green light (i.e., 400-550 nm) to capture their emission spanning from 550 to 750 nm. Arginine and folic acid functionalized nanoparticles have been demonstrated as fluorescent cell labels where blue and green excitation has been used for imaging of labeled cells. The presented method can be extended for the development of carbon nanoparticle-based other bioimaging probes. PMID:27011336

  1. Direct Synthesis of Multicolor Fluorescent Hollow Carbon Spheres Encapsulating Enriched Carbon Dots

    OpenAIRE

    Qiao-Ling Chen; Wen-Qing Ji; Su Chen

    2016-01-01

    Multicolor fluorescent hollow carbon spheres (HCSs) are fabricated by an easy one-step route of in situ pyrolysis process with the use of natural scales and collagen powders as the precursor. The gas blow forming mechanism and photoluminescence (PL) emission mechanism of HCSs have been thoroughly discussed and proved that HCSs represent the first examples of three-dimensional multicolor fluorescent nanomaterials based on carbon dots (CDs). The HCSs encapsulate enriched carbon dots with high q...

  2. Facile and green approach to prepare fluorescent carbon dots: Emergent nanomaterial for cell imaging and detection of vitamin B2.

    Science.gov (United States)

    Kundu, Aniruddha; Nandi, Sudipta; Das, Pradip; Nandi, Arun K

    2016-04-15

    Carbon dots (CDs) are a new representative in carbonaceous family and have initiated remarkable research interests over the past one decade in a large variety of fields. Herein, we have utilized a facile, one-step carbonization method to prepare fluorescent carbon dots using poly(vinyl alcohol) (PVA) both as a carbon source and as a surface passivating agent. The as prepared CDs emit bright blue fluorescence under ultraviolet illumination. The structure and optical properties of the CDs are thoroughly investigated by several methods such as high-resolution transmission electron microscopy; dynamic light scattering; UV-vis, fluorescence and Fourier transform infrared spectroscopy. The CDs exhibit excellent water solubility and demonstrate average hydrodynamic diameter of 11.3 nm, holding great promise for biological applications. The biocompatibility evaluation and in vitro imaging study reveals that the synthesized CDs can be used as effective fluorescent probes in bio-imaging without noticeable cytotoxicity. In addition, a unique sensor for the detection of vitamin B2 in aqueous solution is proposed on the basis of spontaneous fluorescence resonance energy transfer from CD to vitamin B2. These findings therefore suggest that the CDs can find potential applications in cellular imaging along with sensing of vitamin B2. PMID:26852351

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

    Science.gov (United States)

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

    2016-07-01

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

  4. A bright cyan-excitable orange fluorescent protein facilitates dual-emission microscopy and enhances bioluminescence imaging in vivo.

    Science.gov (United States)

    Chu, Jun; Oh, Younghee; Sens, Alex; Ataie, Niloufar; Dana, Hod; Macklin, John J; Laviv, Tal; Welf, Erik S; Dean, Kevin M; Zhang, Feijie; Kim, Benjamin B; Tang, Clement Tran; Hu, Michelle; Baird, Michelle A; Davidson, Michael W; Kay, Mark A; Fiolka, Reto; Yasuda, Ryohei; Kim, Douglas S; Ng, Ho-Leung; Lin, Michael Z

    2016-07-01

    Orange-red fluorescent proteins (FPs) are widely used in biomedical research for multiplexed epifluorescence microscopy with GFP-based probes, but their different excitation requirements make multiplexing with new advanced microscopy methods difficult. Separately, orange-red FPs are useful for deep-tissue imaging in mammals owing to the relative tissue transmissibility of orange-red light, but their dependence on illumination limits their sensitivity as reporters in deep tissues. Here we describe CyOFP1, a bright, engineered, orange-red FP that is excitable by cyan light. We show that CyOFP1 enables single-excitation multiplexed imaging with GFP-based probes in single-photon and two-photon microscopy, including time-lapse imaging in light-sheet systems. CyOFP1 also serves as an efficient acceptor for resonance energy transfer from the highly catalytic blue-emitting luciferase NanoLuc. An optimized fusion of CyOFP1 and NanoLuc, called Antares, functions as a highly sensitive bioluminescent reporter in vivo, producing substantially brighter signals from deep tissues than firefly luciferase and other bioluminescent proteins. PMID:27240196

  5. A low cytotoxic and ratiometric fluorescent nanosensor based on carbon-dots for intracellular pH sensing and mapping

    Science.gov (United States)

    Du, Fangkai; Ming, Yunhao; Zeng, Fang; Yu, Changmin; Wu, Shuizhu

    2013-09-01

    Intracellular pH plays a critical role in the function of cells, and its regulation is essential for most cellular processes. In this study, we demonstrate a fluorescence resonance energy transfer (FRET)-based ratiometric pH nanosensor with carbon-dot (CD) as the carrier. The sensor was prepared by covalently linking a pH-sensitive fluorescent dye (fluorescein isothiocyanate, FITC) onto carbon-dot. As the FRET donor, the carbon-dot exhibits bright fluorescence emission as well as λex-dependent photoluminescence emission, and a suitable excitation wavelength for the donor (CD) can be chosen to match the energy acceptor (fluorescein moiety). The fluorescein moieties on a CD undergo structural and spectral conversion as the pH changes, affording the nanoplatform a FRET-based pH sensor. The CD-based system exhibits a significant change in fluorescence intensity ratio between pH 4 and 8 with a pKa value of 5.69. It also displays excellent water dispersibility, good spectral reversibility, satisfactory cell permeability and low cytotoxicity. Following the living cell uptake, this nanoplatform with dual-chromatic emissions can facilitate real-time visualization of the pH evolution involved in the endocytic pathway of the nanosensor. This reversible and low cytotoxic fluorescent nanoplatform may be highly valuable in a variety of biological studies, such as endocytic trafficking, endosome/lysosome maturation, and pH regulation in subcellular organelles.

  6. Highly fluorescent xerogels with entrapped carbon dots for organic scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Quaranta, A., E-mail: quaranta@ing.unitn.it [University of Trento, Department of Industrial Engineering, via Mesiano, 77, 38123 Trento (Italy); Laboratori Nazionali di Legnaro, INFN, Viale dell' Università, 2, 35020 Legnaro (PD) (Italy); Carturan, S. [Laboratori Nazionali di Legnaro, INFN, Viale dell' Università, 2, 35020 Legnaro (PD) (Italy); University of Padova, Department of Physics and Astronomy “Galileo Galilei”, Via Marzolo, 8, 35131 Padova (Italy); Campagnaro, A.; Dalla Palma, M. [University of Trento, Department of Industrial Engineering, via Mesiano, 77, 38123 Trento (Italy); Laboratori Nazionali di Legnaro, INFN, Viale dell' Università, 2, 35020 Legnaro (PD) (Italy); Giarola, M.; Daldosso, N. [University of Verona, Department of Informatics, Strada le Grazie,15, 37134 Verona (Italy); Maggioni, G. [Laboratori Nazionali di Legnaro, INFN, Viale dell' Università, 2, 35020 Legnaro (PD) (Italy); University of Padova, Department of Physics and Astronomy “Galileo Galilei”, Via Marzolo, 8, 35131 Padova (Italy); Mariotto, G. [University of Verona, Department of Informatics, Strada le Grazie,15, 37134 Verona (Italy)

    2014-02-28

    Organically modified silicate thin film and bulk samples were prepared using [3-(2-aminoethylamino)propyl]trimethoxysilane (AEAP-TMOS) as precursor with the addition of different amounts of AEAP-TMOS functionalized C-dots, prepared by reaction of AEAP-TMOS and citric acid at high temperature. The synthesis of surface functionalized C-dots was followed by Fourier Transform Infrared (FTIR) spectroscopy, and the C-dots optical properties were characterized by optical absorption and UV–vis fluorescence. Thin xerogel films and bulk samples were studied by FTIR, Raman and fluorescence spectroscopy. Intense blue-green emission was observed by UV excitation of functionalized C-dots. Carbon quantum dot (CQD) luminescence was preserved also in the xerogel matrices, and the energy transfer from the matrix to CQDs, which is a key characteristic for scintillation detectors, was investigated in the two systems. - Highlights: • Functionalized carbon dots were synthesized. • Carbon dots were dispersed in hybrid xerogel bulk and thin film. • Carbon dots exhibit a strong tunable blue luminescence. • Xerogels were characterized by FT-IR, Raman and fluorescence spectroscopies. • Energy transfer processes were evidenced between C-dots and xerogel matrix.

  7. Fluorescence characteristics of water soluble organic carbon in eastern China

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Fluorescence excitation and average molecular weight of 46 water soluble organic matter (WSOC) samples extracted from 20 soil types in eastern China were determined. It was found all samples shared similar spectroscopy. A good linear relationship existed between total organic carbon and excitation in the range of 350 to 450 nm though the content of organic carbon and pH of the samples vary in a wide range. No significant correlation between relative excitation intensity and average molecular weight of WSOC and FA was found, but the partial correlation became significant with pH as the controlling factor for WSOC samples. The relative excitation intensity showed a general trend of increasing from south to north in the study area. The pH value might play an important role in regulating the fluorescent spatial variation of WSOC.

  8. The complex environment of the bright carbon star TX Psc as probed by spectro-astrometry

    CERN Document Server

    Hron, J; Aringer, B; Klotz, D; Lebzelter, T; Paladini, C; Wiedemann, G

    2015-01-01

    Context: Stars on the asymptotic giant branch (AGB) show broad evidence of inhomogeneous atmospheres and circumstellar envelopes. These have been studied by a variety of methods on various angular scales. In this paper we explore the envelope of the well-studied carbon star TX Psc by the technique of spectro-astrometry. Aims: We explore the potential of this method for detecting asymmetries around AGB stars. Methods:We obtained CRIRES observations of several CO $\\Delta$v=1 lines near 4.6 $\\mu$m and HCN lines near 3 $\\mu$m in 2010 and 2013. These were then searched for spectro-astrometric signatures. For the interpretation of the results, we used simple simulated observations. Results: Several lines show significant photocentre shifts with a clear dependence on position angle. In all cases, tilde-shaped signatures are found where the positive and negative shifts (at PA 0deg) are associated with blue and weaker red components of the lines. The shifts can be modelled with a bright blob 70 mas to 210 mas south of...

  9. Fluorescently tuned nitrogen-doped carbon dots from carbon source with different content of carboxyl groups

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hao; Wang, Yun; Dai, Xiao; Zou, Guifu, E-mail: kqzhang@suda.edu.cn, E-mail: zouguifu@suda.edu.cn [College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Gao, Peng; Zhang, Ke-Qin, E-mail: kqzhang@suda.edu.cn, E-mail: zouguifu@suda.edu.cn; Du, Dezhuang [National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, Suzhou 215123 (China); Guo, Jun [Testing and Analysis Center, Soochow University, Suzhou 215123 (China)

    2015-08-01

    In this study, fluorescent nitrogen-doped carbon dots (NCDs) were tuned via varying the sources with different number of carboxyl groups. Owing to the interaction between amino and carboxyl, more amino groups conjugate the surface of the NCDs by the source with more carboxyl groups. Fluorescent NCDs were tuned via varying the sources with different content of carboxyl groups. Correspondingly, the nitrogen content, fluorescence quantum yields and lifetime of NCDs increases with the content of carboxyl groups from the source. Furthermore, cytotoxicity assay and cell imaging test indicate that the resultant NCDs possess low cytotoxicity and excellent biocompatibility.

  10. Fluorescently tuned nitrogen-doped carbon dots from carbon source with different content of carboxyl groups

    International Nuclear Information System (INIS)

    In this study, fluorescent nitrogen-doped carbon dots (NCDs) were tuned via varying the sources with different number of carboxyl groups. Owing to the interaction between amino and carboxyl, more amino groups conjugate the surface of the NCDs by the source with more carboxyl groups. Fluorescent NCDs were tuned via varying the sources with different content of carboxyl groups. Correspondingly, the nitrogen content, fluorescence quantum yields and lifetime of NCDs increases with the content of carboxyl groups from the source. Furthermore, cytotoxicity assay and cell imaging test indicate that the resultant NCDs possess low cytotoxicity and excellent biocompatibility

  11. Fluorescent Carbon Quantum Dots as Single Light Converter for White LEDs

    Science.gov (United States)

    Feng, Xiaoting; Zhang, Feng; Wang, Yaling; Zhang, Yi; Yang, Yongzhen; Liu, Xuguang

    2016-06-01

    Synthesis of fluorescent carbon quantum dots (CQDs) as single light converter and their application in white light-emitting diodes (LEDs) are reported. CQDs were prepared by a one-step hydrothermal method using glucose and polyethylene glycol 200 as precursors. The structural and optical properties of the CQDs were investigated. The CQDs with uniform size of 4 nm possessed typical excitation-dependent emission wavelength and quantum yield of 3.5%. Under ultraviolet illumination, the CQDs in deionized water emitted bright blue fluorescence and produced broad visible-light emission with high red, green, and blue spectral component ratio of 63.5% (red-to-blue intensity to total intensity), suggesting great potential as single light converter for white LEDs. To demonstrate their potential, a white LED using CQDs as a single light converter was built. The device exhibited cool white light with corresponding color temperature of 5584 K and color coordinates of (0.32, 0.37), belonging to the white gamut. This research suggests that CQDs could be a promising candidate single light converter for white LEDs.

  12. Aptamer carbon nanodot sandwich used for fluorescent detection of protein.

    Science.gov (United States)

    Xu, Bailu; Zhao, Chuanqi; Wei, Weili; Ren, Jinsong; Miyoshi, Daisuke; Sugimoto, Naoki; Qu, Xiaogang

    2012-12-01

    Carbon nanodots (C-Dots) have attracted growing interest in recent years due to their low cost, ready scalability, excellent chemical stability, biocompatibility, colloidal stability, and resilience of photoluminescence. They have been employed as novel, ideal fluorescent probes for bio-imaging and smart sensing. In addition, taking advantage of their low-cytotoxicity, C-Dots have potential applications in biochemical and cell biological fields. Herein, we present the first assay with aptamer-functionalized C-Dots as a sensory platform for protein detection. The presence of thrombin can induce the aptamer-modified fluorescent C-Dots to form a sandwich structure with aptamer-functionalized silica nanoparticles through specific protein/aptamer interaction. The assay shows high specificity toward thrombin. A detection limit of 1 nM is obtained, which is significantly improved as compared to that of many previously reported fluorescence-based thrombin detection assays. Using other modified aptamers and antibodies instead of thrombin binding aptamers, this strategy may offer a suitable approach for detection of other proteins in biological, pharmaceutical and nano-mechanical applications. PMID:23050264

  13. 水热法合成仙人掌荧光碳量子点的研究%Study on the Synthesis of Fluorescent Carbon Dots by Cactus

    Institute of Scientific and Technical Information of China (English)

    杨欢; 黄小梅; 邓祥; 吴狄; 李红琼; 郭开雨; 罗琼

    2015-01-01

    Fluorescent carbon dots utilizing cactus as a carbon source via hydrothermal method was developed. Fluorescent carbon dots were characterized by fluorescence spectroscopy. The effect of the amount of cactus, reaction time and reaction temperature on hydrothermal synthesis process was investigated in the present work. The results indicated that when the total volume of the solvent water was 30 mL, 0. 5 g of cactus used was optimal because the obtained fluorescent carbon dots showed the highest luminescent efficiency. Besides, the optimized reaction time and temperature were set at 3 h and 160 ℃ owing to fluorescent carbon dots with the highest fluorescent intensities. The fluorescent carbon dots can emit bright green photoluminescence under UV excitation.%以仙人掌为碳源,通过水热法合成了荧光碳量子点,并通过荧光光谱对样品的光学性能进行了表征,同时考察了仙人掌用量、水热反应时间和温度对合成荧光碳量子点的影响。结果显示:以仙人掌为碳源合成的荧光碳量子点在水溶剂30 mL条件下,仙人掌质量为0.5 g时得到的荧光碳量子点发光效率最高;同时,水热反应时间为3 h,反应温度为160℃时得到的荧光碳量子点发光强度最高。荧光碳量子点在紫外灯照射下发出明亮的绿光。

  14. Ammonium hydroxide modulated synthesis of high-quality fluorescent carbon dots for white LEDs with excellent color rendering properties

    Science.gov (United States)

    Wang, Shengda; Zhu, Zhifeng; Chang, Yajing; Wang, Hui; Yuan, Nan; Li, Guopeng; Yu, Dabin; Jiang, Yang

    2016-07-01

    A novel type of aqueous fluorescent carbon dot (CD) was synthesized using citric acid as the only carbon source via an ammonium hydroxide modulated method, providing a blue color gamut. The amino group is considered to be the key factor in the high fluorescence of CDs and a model is established to investigate the mechanism of fluorescence. In addition, white light-emitting diodes (WLEDs) are fabricated by utilizing the prepared CDs and rare earth luminescent materials (SrSi2O2N2:Eu and Sr2Si5N8:Eu) as color conversion layers and UV-LED chips as the excitation light source. The WLEDs produce bright white light with attractive color rendering properties including a color rendering index of up to 95.1, a CIE coordinate of (0.33, 0.37), and a T c of 5447 K under a 100 mA driven current, indicating that the CDs are promising in the field of optoelectronic devices.

  15. Amino-functionalized green fluorescent carbon dots as surface energy transfer biosensors for hyaluronidase

    Science.gov (United States)

    Liu, Siyu; Zhao, Ning; Cheng, Zhen; Liu, Hongguang

    2015-04-01

    Amino-functionalized fluorescent carbon dots have been prepared by hydrothermal treatment of glucosamine with excess pyrophosphate. The produced carbon dots showed stabilized green emission fluorescence at various excitation wavelengths and pH environments. Herein, we demonstrate the surface energy transfer between the amino-functionalized carbon dots and negatively charged hyaluronate stabilized gold nanoparticles. Hyaluronidase can degrade hyaluronate and break down the hyaluronate stabilized gold nanoparticles to inhibit the surface energy transfer. The developed fluorescent carbon dot/gold nanoparticle system can be utilized as a biosensor for sensitive and selective detection of hyaluronidase by two modes which include fluorescence measurements and colorimetric analysis.Amino-functionalized fluorescent carbon dots have been prepared by hydrothermal treatment of glucosamine with excess pyrophosphate. The produced carbon dots showed stabilized green emission fluorescence at various excitation wavelengths and pH environments. Herein, we demonstrate the surface energy transfer between the amino-functionalized carbon dots and negatively charged hyaluronate stabilized gold nanoparticles. Hyaluronidase can degrade hyaluronate and break down the hyaluronate stabilized gold nanoparticles to inhibit the surface energy transfer. The developed fluorescent carbon dot/gold nanoparticle system can be utilized as a biosensor for sensitive and selective detection of hyaluronidase by two modes which include fluorescence measurements and colorimetric analysis. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr00070j

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

    Directory of Open Access Journals (Sweden)

    Fuminari Uehara

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

  17. Single-Walled Carbon Nano tubes as Fluorescence Biosensors for Pathogen Recognition in Water Systems

    International Nuclear Information System (INIS)

    The possibility of using single-walled carbon nanotubes (SWCNTs) aggregates as fluorescence sensors for pathogen recognition in drinking water treatment applications has been studied. Batch adsorption study is conducted to adsorb large concentrations of Staphylococcus aureus aureus SH 1000 and Escherichia coli pKV-11 on single-walled carbon nanotubes. Subsequently the immobilized bacteria are detected with confocal microscopy by coating the nanotubes with fluorescence emitting antibodies. The Freundlich adsorption equilibrium constant (k) for S.aureus and E.coli determined from batch adsorption study was found to be 9 x108 and 2 x108 ml/g, respectively. The visualization of bacterial cells adsorbed on fluorescently modified carbon nanotubes is also clearly seen. The results indicate that hydrophobic single-walled carbon nanotubes have excellent bacterial adsorption capacity and fluorescent detection capability. This is an important advancement in designing fluorescence biosensors for pathogen recognition in water systems.

  18. Single-Walled Carbon Nanotubes as Fluorescence Biosensors for Pathogen Recognition in Water Systems

    Directory of Open Access Journals (Sweden)

    Venkata K. K. Upadhyayula

    2008-01-01

    Full Text Available The possibility of using single-walled carbon nanotubes (SWCNTs aggregates as fluorescence sensors for pathogen recognition in drinking water treatment applications has been studied. Batch adsorption study is conducted to adsorb large concentrations of Staphylococcus aureus aureus SH 1000 and Escherichia coli pKV-11 on single-walled carbon nanotubes. Subsequently the immobilized bacteria are detected with confocal microscopy by coating the nanotubes with fluorescence emitting antibodies. The Freundlich adsorption equilibrium constant (k for S.aureus and E.coli determined from batch adsorption study was found to be 9×108 and 2×108 ml/g, respectively. The visualization of bacterial cells adsorbed on fluorescently modified carbon nanotubes is also clearly seen. The results indicate that hydrophobic single-walled carbon nanotubes have excellent bacterial adsorption capacity and fluorescent detection capability. This is an important advancement in designing fluorescence biosensors for pathogen recognition in water systems.

  19. Avaliação do método de triagem para análise de milho contaminado com aflatoxinas pela fluorescência amarelo-esverdeada brilhante (BGYF- Bright Greenish Yellow Fluorescence Evaluation of a screening method of aflatoxin in corn by Bright Greenish Yellow Fluorescence

    Directory of Open Access Journals (Sweden)

    M.E.T. PALOMINO

    1998-01-01

    Full Text Available A técnica da fluorescência amarelo-esverdeada brilhante (BGYF como método de triagem na avaliação de milho eventualmente contaminado com aflatoxina, utilizada por uma indústria alimentícia do Estado de São Paulo em 61 amostras de milho, foi comparada com a técnica BGYF padronizada, aplicada em laboratório antes e após trituração dos grãos e, também, com a técnica da cromatografia em camada delgada (CCD. Os resultados da indústria geraram menor número de resultados falso-positivos do que a técnica BGYF padronizada. Por outro lado, apenas os resultados da indústria apresentaram amostras falso-negativas, ao contrário da BGYF padronizada, que não as apresentou. Conclui-se que existe uma inadequação do número de pontos fluorescentes adotados como critério de rejeição em ambas as técnicas, devendo-se proceder estudos, com maior número de amostras, para determinar o número adequado de pontos fluorescentes a ser adotado como critério além de outros fatores que possam influenciar a metodologia.The bright greenish yellow fluorescence technique (BGYF is a screening method for the evaluation of corn occasionally contaminated by aflatoxins, used by an industry of the State of São Paulo on sixty one samples, was compared with laboratory results of the BGYF standard technique, before and after crushing the grains, and also with thin layer chromatographic analysis. The industry showed results with a smaller number of false positives than the BGYF standard technique. However, the industry showed false negative results and the BGYF standard technique did not. It was concluded that the number of fluorescent points adopted, as a rejection criterion, in both techniques, was inadequate and studies should be developed with more samples to determine the adequate number of fluorescent points to be adopted as a rejection criterion and the influence of other factors.

  20. Improving brightness and photostability of green and red fluorescent proteins for live cell imaging and FRET reporting.

    Science.gov (United States)

    Bajar, Bryce T; Wang, Emily S; Lam, Amy J; Kim, Bongjae B; Jacobs, Conor L; Howe, Elizabeth S; Davidson, Michael W; Lin, Michael Z; Chu, Jun

    2016-01-01

    Many genetically encoded biosensors use Förster resonance energy transfer (FRET) to dynamically report biomolecular activities. While pairs of cyan and yellow fluorescent proteins (FPs) are most commonly used as FRET partner fluorophores, respectively, green and red FPs offer distinct advantages for FRET, such as greater spectral separation, less phototoxicity, and lower autofluorescence. We previously developed the green-red FRET pair Clover and mRuby2, which improves responsiveness in intramolecular FRET reporters with different designs. Here we report the engineering of brighter and more photostable variants, mClover3 and mRuby3. mClover3 improves photostability by 60% and mRuby3 by 200% over the previous generation of fluorophores. Notably, mRuby3 is also 35% brighter than mRuby2, making it both the brightest and most photostable monomeric red FP yet characterized. Furthermore, we developed a standardized methodology for assessing FP performance in mammalian cells as stand-alone markers and as FRET partners. We found that mClover3 or mRuby3 expression in mammalian cells provides the highest fluorescence signals of all jellyfish GFP or coral RFP derivatives, respectively. Finally, using mClover3 and mRuby3, we engineered an improved version of the CaMKIIα reporter Camuiα with a larger response amplitude. PMID:26879144

  1. In Vivo Fluorescence Imaging in the Second Near-Infrared Window Using Carbon Nanotubes.

    Science.gov (United States)

    Hong, Guosong; Dai, Hongjie

    2016-01-01

    In vivo fluorescence imaging in the second near-infrared window (NIR-II window, 1000-1700 nm) is a powerful imaging technique that emerged in recent years. This imaging tool allows for noninvasive, deep-tissue visualization and interrogation of anatomical features and functions with improved imaging resolution and contrast at greater tissue penetration depths than traditional fluorescence imaging. Here, we present the detailed protocol for conducting NIR-II fluorescence imaging in live animals, including the procedures for preparation of biocompatible and NIR-II fluorescent carbon nanotube solution, live animal administration and NIR-II fluorescence image acquisition. PMID:27283426

  2. A Bright Fluorescent Probe for H2S Enables Analyte-Responsive, 3D Imaging in Live Zebrafish Using Light Sheet Fluorescence Microscopy.

    Science.gov (United States)

    Hammers, Matthew D; Taormina, Michael J; Cerda, Matthew M; Montoya, Leticia A; Seidenkranz, Daniel T; Parthasarathy, Raghuveer; Pluth, Michael D

    2015-08-19

    Hydrogen sulfide (H2S) is a critical gaseous signaling molecule emerging at the center of a rich field of chemical and biological research. As our understanding of the complexity of physiological H2S in signaling pathways evolves, advanced chemical and technological investigative tools are required to make sense of this interconnectivity. Toward this goal, we have developed an azide-functionalized O-methylrhodol fluorophore, MeRho-Az, which exhibits a rapid >1000-fold fluorescence response when treated with H2S, is selective for H2S over other biological analytes, and has a detection limit of 86 nM. Additionally, the MeRho-Az scaffold is less susceptible to photoactivation than other commonly used azide-based systems, increasing its potential application in imaging experiments. To demonstrate the efficacy of this probe for H2S detection, we demonstrate the ability of MeRho-Az to detect differences in H2S levels in C6 cells and those treated with AOAA, a common inhibitor of enzymatic H2S synthesis. Expanding the use of MeRho-Az to complex and heterogeneous biological settings, we used MeRho-Az in combination with light sheet fluorescence microscopy (LSFM) to visualize H2S in the intestinal tract of live zebrafish. This application provides the first demonstration of analyte-responsive 3D imaging with LSFM, highlighting the utility of combining new probes and live imaging methods for investigating chemical signaling in complex multicellular systems. PMID:26061541

  3. Solvothermal synthesis of green-fluorescent carbon nanoparticles and their application

    International Nuclear Information System (INIS)

    A novel solvothermal approach to synthesize green-fluorescent carbon nanoparticles (CNPs) was developed using L-ascorbic acid as the carbon source, glycol and triple distilled water as the solvent. The CNPs emit strong green fluorescence under UV irradiation, and the fluorescence intensity showed a good linear relationship with pH value within a certain range. Direct yeast cell labeling was achieved through cell endocytosis of these CNPs. - Highlights: ► A one-step approach to synthesize fluorescent carbon nanoparticles was developed. ► A linear relationship between fluorescence intensity and pH value was observed. ► Direct labeling of yeast cells was realized successfully with the CNPs.

  4. Determination of sunset yellow in soft drinks based on fluorescence quenching of carbon dots.

    Science.gov (United States)

    Yuan, Yusheng; Zhao, Xin; Qiao, Man; Zhu, Jinghui; Liu, Shaopu; Yang, Jidong; Hu, Xiaoli

    2016-10-01

    Fluorescent carbon dots was prepared by heating N-(2-hydroxyethyl)ethylene diaminetriacetic acid in air. The carbon dots were not only highly soluble in water but also uniform in size, and possessed strong blue fluorescence and excitation wavelength-dependent emission properties with the maximum excitation and emission wavelength at 366nm and 423nm, respectively. Food colorant sunset yellow whose excitation and emission wavelength at 303nm and 430nm could selectively quench the fluorescence of carbon dots, efficient fluorescent resonance energy transfer between the carbon dots and sunset yellow is achieved. This was exploited to design a method for the determination of sunset yellow in the concentration range from 0.3 to 8.0μmolL(-1), with a limit of detection (3σ/k) of 79.6nmolL(-1). Furthermore the fluorimetric detection method was established and validated for sunset yellow in soft drinks samples with satisfactory results. PMID:27262658

  5. Synthesis and properties of core–shell fluorescent hybrids with distinct morphologies based on carbon dots

    KAUST Repository

    Markova, Zdenka

    2012-01-01

    Fluorescent core-shell nanohybrids with the shells derived from carbon dots and cores differing in the chemical nature and morphology were synthesized. Hybrid nanoparticles combine fluorescence with other functionalities such as magnetic response on a single platform. These hybrids can be used in various bioapplications as demonstrated with labeling of stem cells. © The Royal Society of Chemistry 2012.

  6. White carbon: Fluorescent carbon nanoparticles with tunable quantum yield in a reproducible green synthesis

    Science.gov (United States)

    Meiling, Till T.; Cywiński, Piotr J.; Bald, Ilko

    2016-01-01

    In this study, a new reliable, economic, and environmentally-friendly one-step synthesis is established to obtain carbon nanodots (CNDs) with well-defined and reproducible photoluminescence (PL) properties via the microwave-assisted hydrothermal treatment of starch and Tris-acetate-EDTA (TAE) buffer as carbon sources. Three kinds of CNDs are prepared using different sets of above mentioned starting materials. The as-synthesized CNDs: C-CND (starch only), N-CND 1 (starch in TAE) and N-CND 2 (TAE only) exhibit highly homogenous PL and are ready to use without need for further purification. The CNDs are stable over a long period of time (>1 year) either in solution or as freeze-dried powder. Depending on starting material, CNDs with PL quantum yield (PLQY) ranging from less than 1% up to 28% are obtained. The influence of the precursor concentration, reaction time and type of additives on the optical properties (UV-Vis absorption, PL emission spectrum and PLQY) is carefully investigated, providing insight into the chemical processes that occur during CND formation. Remarkably, upon freeze-drying the initially brown CND-solution turns into a non-fluorescent white/slightly brown powder which recovers PL in aqueous solution and can potentially be applied as fluorescent marker in bio-imaging, as a reduction agent or as a photocatalyst. PMID:27334409

  7. White carbon: Fluorescent carbon nanoparticles with tunable quantum yield in a reproducible green synthesis

    Science.gov (United States)

    Meiling, Till T.; Cywiński, Piotr J.; Bald, Ilko

    2016-06-01

    In this study, a new reliable, economic, and environmentally-friendly one-step synthesis is established to obtain carbon nanodots (CNDs) with well-defined and reproducible photoluminescence (PL) properties via the microwave-assisted hydrothermal treatment of starch and Tris-acetate-EDTA (TAE) buffer as carbon sources. Three kinds of CNDs are prepared using different sets of above mentioned starting materials. The as-synthesized CNDs: C-CND (starch only), N-CND 1 (starch in TAE) and N-CND 2 (TAE only) exhibit highly homogenous PL and are ready to use without need for further purification. The CNDs are stable over a long period of time (>1 year) either in solution or as freeze-dried powder. Depending on starting material, CNDs with PL quantum yield (PLQY) ranging from less than 1% up to 28% are obtained. The influence of the precursor concentration, reaction time and type of additives on the optical properties (UV-Vis absorption, PL emission spectrum and PLQY) is carefully investigated, providing insight into the chemical processes that occur during CND formation. Remarkably, upon freeze-drying the initially brown CND-solution turns into a non-fluorescent white/slightly brown powder which recovers PL in aqueous solution and can potentially be applied as fluorescent marker in bio-imaging, as a reduction agent or as a photocatalyst.

  8. One-pot green synthesis of carbon dots by using Saccharum officinarum juice for fluorescent imaging of bacteria (Escherichia coli) and yeast (Saccharomyces cerevisiae) cells

    Energy Technology Data Exchange (ETDEWEB)

    Mehta, Vaibhavkumar N. [Applied Chemistry Department, S. V. National Institute of Technology, Surat, 395 007 (India); Jha, Sanjay [Gujarat Agricultural Biotechnology Institute, Navsari Agricultural University, Surat, 395007 (India); Kailasa, Suresh Kumar, E-mail: sureshkumarchem@gmail.com [Applied Chemistry Department, S. V. National Institute of Technology, Surat, 395 007 (India)

    2014-05-01

    We are reporting highly economical plant-based hydrothermal method for one-pot green synthesis of water-dispersible fluorescent carbon dots (CDs) by using Saccharum officinarum juice as precursor. The synthesized CDs were characterized by UV-visible, fluorescence, Fourier transform infrared (FT-IR), dynamic light scattering (DLS), high-resolution transmission electron microscopic (HR-TEM), and laser scanning confocal microscopic techniques. The CDs are well dispersed in water with an average size of ∼ 3 nm and showed bright blue fluorescence under UV-light (λ{sub ex} = 365 nm). These CDs acted as excellent fluorescent probes in cellular imaging of bacteria (Escherichia coli) and yeast (Saccharomyces cerevisiae). - Highlights: • One-pot green synthesis was used for fluorescent CDs. • FT-IR, DLS, and TEM were used for the characterization of CDs. • The CDs are well dispersed in water with an average size of ∼ 3 nm. • The CDs acted as fluorescent probes for imaging of bacteria and yeast cells.

  9. One-pot green synthesis of carbon dots by using Saccharum officinarum juice for fluorescent imaging of bacteria (Escherichia coli) and yeast (Saccharomyces cerevisiae) cells

    International Nuclear Information System (INIS)

    We are reporting highly economical plant-based hydrothermal method for one-pot green synthesis of water-dispersible fluorescent carbon dots (CDs) by using Saccharum officinarum juice as precursor. The synthesized CDs were characterized by UV-visible, fluorescence, Fourier transform infrared (FT-IR), dynamic light scattering (DLS), high-resolution transmission electron microscopic (HR-TEM), and laser scanning confocal microscopic techniques. The CDs are well dispersed in water with an average size of ∼ 3 nm and showed bright blue fluorescence under UV-light (λex = 365 nm). These CDs acted as excellent fluorescent probes in cellular imaging of bacteria (Escherichia coli) and yeast (Saccharomyces cerevisiae). - Highlights: • One-pot green synthesis was used for fluorescent CDs. • FT-IR, DLS, and TEM were used for the characterization of CDs. • The CDs are well dispersed in water with an average size of ∼ 3 nm. • The CDs acted as fluorescent probes for imaging of bacteria and yeast cells

  10. Fluorescence characteristics of carbon nanoemitters derived from sucrose by green hydrothermal and microwave methods.

    Science.gov (United States)

    Patidar, Rajesh; Rebary, Babulal; Bhadu, Gopala Ram

    2016-12-01

    In this work, fluorescent carbon nanoparticles (CNPs) were prepared through two green methods i.e. microwave and hydrothermal, using sucrose as carbon precursor. Both of these methods have offered fluorescent CNPs as characterized by TEM, FTIR, zeta potential, absorbance and emission techniques. Excitation dependent emission spectra were exhibited by aqueous dispersion of these CNPs when they were subjected to different excitation wavelengths. The luminous characteristics of CNPs obtained from both of these methods were studied and compared. Their fluorescence stability in water and buffer was monitored for about three months. Influence of pH and various metal ions on emission spectra were investigated. PMID:27314910

  11. Easy synthesis and imaging applications of cross-linked green fluorescent hollow carbon nanoparticles.

    Science.gov (United States)

    Fang, Youxing; Guo, Shaojun; Li, Dan; Zhu, Chengzhou; Ren, Wen; Dong, Shaojun; Wang, Erkang

    2012-01-24

    We propose an ingenious method for synthesizing cross-linked hollow fluorescent carbon nanoparticles (HFCNs) with green emission by simply mixing acetic acid, water, and diphosphorus pentoxide. This is an automatic method without external heat treatment to rapidly produce large quantities of HFCNs, in contrast to other syntheses of fluorescent carbon nanoparticles that required high temperature, complicated operations, or long reaction times. Characterizations of HFCNs through high-resolution transmission electron microscopy, infrared/Raman spectroscopy, and X-ray diffraction indicate that abundant small oxygenous graphite domains existed and endowed the HFCNs with fluorescent properties. After simple post-treatments, the cross-linked HFCNs can be used for cell-imaging applications. Compared with traditional dyes and CdTe quantum dots, HFCNs are the superior fluorescent bioimaging agent according to their low toxicity, stability, and resistance to photobleaching. The HFCNs were also applied to watermark ink and fluorescent powder, showing their promising potentials for further wide usage. PMID:22188541

  12. Lightweight LED Fluorescent lamp using engineering poly carbonate

    Science.gov (United States)

    Cho, Hyun-Ju; Lee, Jong-Phil

    2014-09-01

    In this study, we developed lightweight LED fluorescent lamp using thermally conductive engineering PC a heat sink instead of metal. In order to secure price competitiveness, we used double extrusion molding which extrude both the heat sink plate and diffuser plate simultaneously. Fabricated fluorescent lamp has less than 20% of weight as compare to glass fluorescent lamp and power consumption is 20.2 watts, luminous efficiency 123.9 lm/W, respectively. Despite the heat conductive plastic is adopted, the system temperature is maintained less than 35° and the thermal resistance is 25 °/W.

  13. Single Particle Dynamic Imaging and Fe3+ Sensing with Bright Carbon Dots Derived from Bovine Serum Albumin Proteins

    Science.gov (United States)

    Yang, Qingxiu; Wei, Lin; Zheng, Xuanfang; Xiao, Lehui

    2015-12-01

    In this work, we demonstrated a convenient and green strategy for the synthesis of highly luminescent and water-soluble carbon dots (Cdots) by carbonizing carbon precursors, i.e., Bovine serum albumin (BSA) nanoparticles, in water solution. Without post surface modification, the as-synthesized Cdots exhibit fluorescence quantum yield (Q.Y.) as high as 34.8% and display superior colloidal stability not only in concentrated salt solutions (e.g. 2 M KCl) but also in a wide range of pH solutions. According to the FT-IR measurements, the Cdots contain many carboxyl groups, providing a versatile route for further chemical and biological functionalization. Through conjugation of Cdots with the transacting activator of transcription (TAT) peptide (a kind of cell penetration peptide (CPP)) derived from human immunodeficiency virus (HIV), it is possible to directly monitor the dynamic interactions of CPP with living cell membrane at single particle level. Furthermore, these Cdots also exhibit a dosage-dependent selectivity toward Fe3+ among other metal ions, including K+, Na+, Mg2+, Hg2+, Co2+, Cu2+, Pb2+ and Al3+. We believed that the Cdots prepared by this strategy would display promising applications in various areas, including analytical chemistry, nanomedicine, biochemistry and so on.

  14. A rapid microwave synthesis of nitrogen-sulfur co-doped carbon nanodots as highly sensitive and selective fluorescence probes for ascorbic acid.

    Science.gov (United States)

    Duan, Junxia; Yu, Jie; Feng, Suling; Su, Li

    2016-06-01

    A ultrafast one-step microwave-assisted method was developed for the synthesis of nitrogen-sulfur co-doped carbon nanodots (N,S-CDs) by using ethylenediamine as the carbon source and sulfamic acid as the surface passivation reagent. The morphology and the properties of N,S-CDs were explored by a series of techniques, such as high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, UV-vis absorption and fluorescence spectroscopy. The prepared N,S-CDs exhibit bright blue photoluminescence with a high fluorescence quantum yield (FLQY) up to 28%, and high stability and excellent water solubility. A N,S-CDs-based fluorescent probe was developed for sensitive detection ascorbic acid (AA) in the presence of Cu(2+), based on the mechanism that AA reduces Cu(2+) to Cu(+), then Cu(+) quenches the fluorescence of N,S-CDs through electron or energy transfer due to the interaction between Cu(+) and thiol ligand on the N,S-CDs surface. The observed linear response concentration range was from 0.057 to 4.0μM to AA with a detection limit as low as 18nM. The probe exhibited a highly selective response toward AA even in the presence of possible interfering substances, such as uric acid and citric acid. Moreover, these promising features made the sensing system used for the analysis of human serum and urine samples. PMID:27130124

  15. Direct Solvent-Derived Polymer-Coated Nitrogen-Doped Carbon Nanodots with High Water Solubility for Targeted Fluorescence Imaging of Glioma.

    Science.gov (United States)

    Wang, Yi; Meng, Ying; Wang, Shanshan; Li, Chengyi; Shi, Wei; Chen, Jian; Wang, Jianxin; Huang, Rongqin

    2015-08-01

    Cancer imaging requires biocompatible and bright contrast-agents with selective and high accumulation in the tumor region but low uptake in normal tissues. Herein, 1-methyl-2-pyrrolidinone (NMP)-derived polymer-coated nitrogen-doped carbon nanodots (pN-CNDs) with a particle size in the range of 5-15 nm are prepared by a facile direct solvothermal reaction. The as-prepared pN-CNDs exhibit stable and adjustable fluorescence and excellent water solubility. Results of a cell viability test (CCK-8) and histology analysis both demonstrate that the pN-CNDs have no obvious cytotoxicity. Most importantly, the pN-CNDs can expediently enter glioma cells in vitro and also mediate glioma fluorescence imaging in vivo with good contrast via elevated passive targeting. PMID:25808813

  16. Eco-friendly carbon-nanodot-based fluorescent paints for advanced photocatalytic systems

    Science.gov (United States)

    Young Park, So; Uk Lee, Hyun; Lee, Young-Chul; Choi, Saehae; Hyun Cho, Dae; Sik Kim, Hee; Bang, Sunghee; Seo, Soonjoo; Chang Lee, Soon; Won, Jonghan; Son, Byung-Chul; Yang, Mino; Lee, Jouhahn

    2015-07-01

    Fluorescent carbon nanomaterials, especially zero-dimensional (0D) carbon nanodots (CDs), are widely used in broad biological and optoelectronic applications. CDs have unique characteristics such as strong fluorescence, biocompatibility, sun-light response, and capability of mass-production. Beyond the previous green CD obtained from harmful natural substances, we report a new type of fluid-based fluorescent CD paints (C-paints) derived from polyethylene glycol (PEG; via simple ultrasound irradiation at room temperatures) and produced in quantum yields of up to ~14%. Additionally, C-paints possess a strong, UV- and visible-light-responsive photoluminescent (PL) property. Most especially, C-paints, by incorporation into a photocatalytic system, show additional roles in the emission of fluorescent light for activation of TiO2 nanoparticles (NPs) and the resultant detoxification of most organic dyes, thus further enabling embarkation in advanced water purification.

  17. One-step synthesis of fluorescent carbon nanoparticles for degradation of naphthol green under visible light

    International Nuclear Information System (INIS)

    A novel solvothermal approach to synthesize fluorescent carbon nanoparticles (CNPs) was developed by using citric acid and ammonium oxalateas as the carbon source, glycol as the solvent. The solution of the as-prepared CNPs emitted strong blue fluorescence under UV 365 nm, and the particles were well- dispersed with an average diameter of about 30–40 nm. The solution of the obtained CNPs was applied to photocatalytic degradation of naphthol green, and the decolorization rate is over 91% when the reaction time reaches more than 5 h under visible light in the presence of hydrogen peroxide. - Highlights: • A one-step synthesis of carbon nanoparticles method was developed. • The citric acid and ammoniumoxalate were used as carbon source for the first time. • The photocatalytic activity of carbon nanoparticles under visible light was evaluated

  18. A novel fluorescent retrograde neural tracer: cholera toxin B conjugated carbon dots

    Science.gov (United States)

    Zhou, Nan; Hao, Zeyu; Zhao, Xiaohuan; Maharjan, Suraj; Zhu, Shoujun; Song, Yubin; Yang, Bai; Lu, Laijin

    2015-09-01

    The retrograde neuroanatomical tracing method is a key technique to study the complex interconnections of the nervous system. Traditional tracers have several drawbacks, including time-consuming immunohistochemical or immunofluorescent staining procedures, rapid fluorescence quenching and low fluorescence intensity. Carbon dots (CDs) have been widely used as a fluorescent bio-probe due to their ultrasmall size, excellent optical properties, chemical stability, biocompatibility and low toxicity. Herein, we develop a novel fluorescent neural tracer: cholera toxin B-carbon dot conjugates (CTB-CDs). It can be taken up and retrogradely transported by neurons in the peripheral nervous system of rats. Our results show that CTB-CDs possess high photoluminescence intensity, good optical stability, a long shelf-life and non-toxicity. Tracing with CTB-CDs is a direct and more economical way of performing retrograde labelling experiments. Therefore, CTB-CDs are reliable fluorescent retrograde tracers.The retrograde neuroanatomical tracing method is a key technique to study the complex interconnections of the nervous system. Traditional tracers have several drawbacks, including time-consuming immunohistochemical or immunofluorescent staining procedures, rapid fluorescence quenching and low fluorescence intensity. Carbon dots (CDs) have been widely used as a fluorescent bio-probe due to their ultrasmall size, excellent optical properties, chemical stability, biocompatibility and low toxicity. Herein, we develop a novel fluorescent neural tracer: cholera toxin B-carbon dot conjugates (CTB-CDs). It can be taken up and retrogradely transported by neurons in the peripheral nervous system of rats. Our results show that CTB-CDs possess high photoluminescence intensity, good optical stability, a long shelf-life and non-toxicity. Tracing with CTB-CDs is a direct and more economical way of performing retrograde labelling experiments. Therefore, CTB-CDs are reliable fluorescent retrograde

  19. Intrinsically fluorescent carbon dots with tunable emission derived from hydrothermal treatment of glucose in the presence of monopotassium phosphate.

    Science.gov (United States)

    Yang, Zheng-Chun; Wang, Miao; Yong, Anna Marie; Wong, Siew Yee; Zhang, Xin-Hai; Tan, Happy; Chang, Alex Yuangchi; Li, Xu; Wang, John

    2011-11-14

    A facile method is developed to synthesize intrinsically fluorescent carbon dots by hydrothermal treatment of glucose in the presence of monopotassium phosphate. The fluorescence emission of the carbon dots thus produced is tunable by simply adjusting the concentration of monopotassium phosphate. PMID:21931886

  20. Ground state C2 density measurement in carbon plume using laser-induced fluorescence spectroscopy

    International Nuclear Information System (INIS)

    The temporal evolution and spatial distribution of C2 molecules produced by laser ablation of a graphite target is studied using optical emission spectroscopy, dynamic imaging and laser-induced fluorescence (LIF) investigations. We observe peculiar bifurcation of carbon plume into two parts; stationary component close to the target surface and a component moving away from the target surface which splits further in two parts as the plume expands. The two distinct plumes are attributed to recombination of carbon species and formation of nanoparticles. The molecular carbon C2 moves with a faster velocity and dies out at ∼ 800 ns whereas the clusters of nanoparticle move with a slower velocity due to their higher mass and can be observed even after 1600 ns. C2 molecules in the d3Πg state were probed for laser-induced fluorescence during ablation of graphite using the Swan (0,0) band at 516.5 nm. The fluorescence spectrum and images of fluorescence d3Πg - a3Πu(0,1)(λ = 563.5 nm) are recorded using a spectrograph attached to the ICCD camera. To get absolute ground state C2 density from fluorescence images, the images are calibrated using complimentary absorption experiment. This study qualitatively helps to get optimum conditions for nanoparticle formation using the laser ablation of graphite target and hence deducing optimum conditions for thin film deposition.

  1. Labeling of human hepatocellular carcinoma cells by hexamethylene diamine modified fluorescent carbon dots

    Science.gov (United States)

    Dong, Wei; Dong, Yan; Wang, Ying; Zhou, Shiqi; Ge, Xin; Sui, Lili; Wang, Jingwen

    2013-12-01

    Fluorescent carbon dots (CDs) were synthesized by a solvothermal method with glucose as carbon source and surface-modified with 1,6-hexamethylene diamine. In this hybrid CDs, the modification played important role for improving the fluorescent performance by introducing nitrogenous compound to passivate CD's surface, making the CDs emit strong fluorescence. The as-prepared CDs were linked with mouse anti-human Alpha fetoprotein (AFP) antibody and goat anti-mouse immunoglobulin (IgG) to directly and indirectly label fixed human hepatocellular carcinoma cells, respectively. The cytotoxicity of these CDs were also tested using the human hepatocellular carcinoma cells. No apparent cytotoxicity was observed, which suggested the potential application of the as-prepared CDs in bioimaging.

  2. 高亮度场发射荧光灯的制备及其性能测试%Fabrication and Properties of High Brightness Field Emission Fluorescence Lamp

    Institute of Scientific and Technical Information of China (English)

    郑旭丹; 胡利勤; 郭太良

    2011-01-01

    利用圆柱形结构的增强效应能提高丝状阴极场发射性能的这个特性,设计了场发射荧光灯.采用热敷法将配制好的碳纳米管(Carbon Nanotubes,CNT)浆料转移到镍丝(Ni)表面制备成丝状阴极,以及溶胶-凝胶法在圆柱形玻璃管内壁制备掺锡氧化铟(Indium Tin Oxide,ITO)薄膜作为阳极,制作场发射荧光灯.测试结果表明,该碳纳米管场发射荧光灯具有良好的场发射性能,开启电场低,仅为0.15 V/μm;CNT的场增强因子βCNT为1967;当驱动电压为4 000 V时,发光亮度达19 800cd/m2.这种亮度高、稳定性好、成本低的场发射荧光灯在照明光源领域具有很大的应用前景.%A novel cylindrical geometry carbon nanotubes (CNT)field emission fluorescence lamp (FEFL)was designed. The CNT paste was transfered to the surface of the nickel wire by thermal coating method ,and the indium tin oxide(ITO) thin film was fabricated in the cylinder glass pipe by sol-gel. The cylinder glass pipe with ITO film and phosphor was used as anode. The FEFL showed superior properties,such as low turn-on electric field of 0.15 V/μm,high brightness of 19 800 cd/m2 at the voltage 4 000 V,and large field enhancement factor of 1967. The FEFL is a very promising candidate as back light source.

  3. Perylenetetracarboxylic anhydride as a precursor of fluorescent carbon nanoonion rings

    Science.gov (United States)

    Baldoví, Herme G.; Herance, José Raul; Manuel Víctor, Víctor; Alvaro, Mercedes; Garcia, Hermenegildo

    2015-07-01

    Thermal annealing at 400 °C of perylenetetracarboxylic anhydride in low molecular mass PEG gives rise to the formation of well defined nanoobjects of 2.5 nm height and size distribution from 10 to 65 nm (average 40 nm) after purification of the raw mixture with silicagel chromatography. TEM reveals that the flat nanoobjects are constituted of concentric graphenic rings (0.34 nm interlayer distance). The morphology of the nanoparticles resembles onion rings of nanometric dimensions (nanoonion rings C-NOR). C-NOR particles have an excitation dependent emission with λem from 430 to 570 nm and a maximum emission quantum yield of 0.49. C-NOR particles can be internalized into Hep3B human hepatoma cells as determined by confocal fluorescence microscopy and are remarkably biocompatible affecting slightly cell viability according to the MTT test.

  4. Uncovering the pKa dependent fluorescence quenching of carbon dots induced by chlorophenols

    Science.gov (United States)

    Zhang, Yu; Wang, Yu; Guan, Yafeng; Feng, Liang

    2015-03-01

    Fluorescence quenching induced by targets is always an alluring strategy to elucidate the possible photoluminescence origin of carbon dots. In this study, a new kind of N, S co-doped carbon dots (NSCDs) was synthesized and the fluorescence of NSCDs was surprisingly found to be quenched by chlorophenols (CPs) in a pKa dependent mode. Detailed investigation of this behavior demonstrated that phenolate was the responsible species and N and/or S dopants in NSCDs failed to play a role in the fluorescence quenching. Further evidence uncovered that the quenching was a static one, where a non-fluorescent intermediate was formed between electron-deficient C&z.dbd;O on the CDs surface and the electron-rich phenolic oxygen anion of chlorophenolate via nucleophilic addition. Moreover, one of the main photoluminescence origins of this kind of CDs was derived, namely surface emissive sites mostly attributed to carbonyl groups.Fluorescence quenching induced by targets is always an alluring strategy to elucidate the possible photoluminescence origin of carbon dots. In this study, a new kind of N, S co-doped carbon dots (NSCDs) was synthesized and the fluorescence of NSCDs was surprisingly found to be quenched by chlorophenols (CPs) in a pKa dependent mode. Detailed investigation of this behavior demonstrated that phenolate was the responsible species and N and/or S dopants in NSCDs failed to play a role in the fluorescence quenching. Further evidence uncovered that the quenching was a static one, where a non-fluorescent intermediate was formed between electron-deficient C&z.dbd;O on the CDs surface and the electron-rich phenolic oxygen anion of chlorophenolate via nucleophilic addition. Moreover, one of the main photoluminescence origins of this kind of CDs was derived, namely surface emissive sites mostly attributed to carbonyl groups. Electronic supplementary information (ESI) available: Texts, figures and tables giving partial experimental procedures, detailed characterizations

  5. A solvothermal method to synthesize fluorescent carbon nanoparticles and application to photocatalysis and electrocatalysis.

    Science.gov (United States)

    Hongren, Li; Feng, Li; Aimin, Deng

    2015-09-01

    A novel solvothermal approach to synthesize fluorescent carbon nanoparticles (CNPs) was developed using glucose and ammonium oxalate as the carbon source, and glycol as the solvent. The solution of as-prepared CNPs emitted blue-green fluorescence under ultraviolet (UV) light at 365 nm, and the carbon nanoparticle formation was investigated through XRD, TEM, DLS, FT-IR, UV, PL, XPS. The particle was well dispersed with an average diameter of about 10-30 nm. In contrast with previous methods, in this synthesis process neither strong acid treatment nor further surface modification was necessary. The solution of as-prepared CNPs were applied to photocatalytic degradation of mountain green in the present H2 O2 , and the decolorization rate was over 97% when the reaction time was more than 7 h under visible light. The as-prepared CNPs were also applied to electrocatalysis and showed excellent electrocatalytic activity. PMID:25408385

  6. Sustainable, Rapid Synthesis of Bright-Luminescent CuInS2-ZnS Alloyed Nanocrystals: Multistage Nano-xenotoxicity Assessment and Intravital Fluorescence Bioimaging in Zebrafish-Embryos

    Science.gov (United States)

    Chetty, S. Shashank; Praneetha, S.; Basu, Sandeep; Sachidanandan, Chetana; Murugan, A. Vadivel

    2016-05-01

    Near-infrared (NIR) luminescent CuInS2-ZnS alloyed nanocrystals (CIZS-NCs) for highly fluorescence bioimaging have received considerable interest in recent years. Owing, they became a desirable alternative to heavy-metal based-NCs and organic dyes with unique optical properties and low-toxicity for bioimaging and optoelectronic applications. In the present study, bright and robust CIZS-NCs have been synthesized within 5 min, as-high-as 230 °C without requiring any inert-gas atmosphere via microwave-solvothermal (MW-ST) method. Subsequently, the in vitro and in vivo nano-xenotoxicity and cellular uptake of the MUA-functionalized CIZS-NCs were investigated in L929, Vero, MCF7 cell lines and zebrafish-embryos. We observed minimal toxicity and acute teratogenic consequences upto 62.5 μg/ml of the CIZS-NCs in zebrafish-embryos. We also observed spontaneous uptake of the MUA-functionalized CIZS-NCs by 3 dpf older zebrafish-embryos that are evident through bright red fluorescence-emission at a low concentration of 7.8 μg/mL. Hence, we propose that the rapid, low-cost, large-scale “sustainable” MW-ST synthesis of CIZS-NCs, is an ideal bio-nanoprobe with good temporal and spatial resolution for rapid labeling, long-term in vivo tracking and intravital-fluorescence-bioimaging (IVBI).

  7. Effect of carbon and nitrogen assimilation on chlorophyll fluorescence emission by the cyanobacterium Anacystis nidulans

    Energy Technology Data Exchange (ETDEWEB)

    Romero, J.M.; Lara, C. (Instituto de Bioquimica Vegetal y Fotosintesis, Univ. de Sevilla y CSIC, Sevilla (ES)); Sivak, M.N. (Dept. of Biochemistry, Michigan State Univ., East Lansing (US))

    1992-01-01

    O{sub 2} evolution and chlorophyll A fluorescence emission have been monitored in intact cells of the cyanobacterium Anacystis nidulans 1402-1 to study the influence of carbon and nitrogen assimilation on the operation of the photosynthetic apparatus. The pattern of fluorescence induction in dark-adapted cyanobacterial cells was different from that of higher plants. Cyanobacteria undergo large, rapid state transitions upon illumination, which lead to marked changes in the fluorescence yield, complicating the estimation of quenching coefficients. The Kautsky effect was not evident, although it could be masked by a state II-state I transition, upon illumination with actinic light. The use of inhibitors of carbon assimilation such as D,L-glyceraldehyde or iodoacetamide allowed us to relate changes in variable fluorescence to active CO{sub 2} fixation. Ammonium, but not nitrate, induced non-photochemical fluorescence quenching, in agreement with a previous report on green algae, indicative of an ammonium-induced state i transition. (au).

  8. Glutathione-mediated mesoporous carbon as a drug delivery nanocarrier with carbon dots as a cap and fluorescent tracer

    Science.gov (United States)

    Zhang, Yang; Han, Lu; Zhang, Yue; Chang, Yan-Qin; Chen, Xu-Wei; He, Rong-Huan; Shu, Yang; Wang, Jian-Hua

    2016-09-01

    This work describes a novel and general redox-responsive controlled drug delivery-release nanocarrier with mesoporous carbon nanoparticles (MCNs) gated by customized fluorescent carbon dots (CDs). The modification of MCNs with a disulfide unit enables the system to be sensitive to intracellular glutathione (GSH). The CDs anchoring onto the surface of the MCNs via an electrostatic interaction block the mesopores and thus prevent the leakage of doxorubicin (DOX) loaded inside the channel of the MCNs. Upon the addition of GSH at the physiological environment, the integrity of the system is disrupted due to the dissociation of the disulfide bond; meanwhile stripping the CDs opens the gate and thus triggers the rapid release of the encapsulated DOX. The fluorescence of the CDs is quenched/‘turned off’ when linking to the MCNs, while it is restored/‘turned on’ when detaching the CDs from the surface of the MCNs. Thus the fluorescent CDs serve as both a controllable drug release gatekeeper and a fluorescent probe for the visualization of the drug delivery process. By combining these inherent capabilities, the present drug delivery system may be a promising route for designing custom-made visual controlled-release nanodevices specifically governed by in situ stimulus in the cells.

  9. Preparation of brightly fluorescent silica nanoparticles modified with lucigenin and chitosan, and their application to an aptamer-based sandwich assay for thrombin

    International Nuclear Information System (INIS)

    We report on the preparation of fluorescent silica nanoparticles (SiNPs) modified with chitosan and lucigenin by using a reverse microemulsion method. The introduction of chitosan to the lucigenin doped SiNPs is shown to improve the fluorescence quantum yield. The modified SiNPs were used as fluorescent markers in an aptamer-based method for selective determination of thrombin. In this protocol, thrombin was sandwiched between streptavidin-coated magnetic beads and the fluorescent SiNPs modified with a thrombin-binding aptamer. The method was successfully applied to the determination of thrombin in human serum and showed a detection limit as low as 0.02 nM. In our perception, the protocol presented here is promising in that such SiNPs may be applied to the sensitive fluorescent detection of other analytes by changing the corresponding aptamer. (author)

  10. Hyperspectral Microscopy of Near-Infrared Fluorescence Enables 17-Chirality Carbon Nanotube Imaging.

    Science.gov (United States)

    Roxbury, Daniel; Jena, Prakrit V; Williams, Ryan M; Enyedi, Balázs; Niethammer, Philipp; Marcet, Stéphane; Verhaegen, Marc; Blais-Ouellette, Sébastien; Heller, Daniel A

    2015-01-01

    The intrinsic near-infrared photoluminescence (fluorescence) of single-walled carbon nanotubes exhibits unique photostability, narrow bandwidth, penetration through biological media, environmental sensitivity, and both chromatic variety and range. Biomedical applications exploiting this large family of fluorophores will require the spectral and spatial resolution of individual (n,m) nanotube species' fluorescence and its modulation within live cells and tissues, which is not possible with current microscopy methods. We present a wide-field hyperspectral approach to spatially delineate and spectroscopically measure single nanotube fluorescence in living systems. This approach resolved up to 17 distinct (n,m) species (chiralities) with single nanotube spatial resolution in live mammalian cells, murine tissues ex vivo, and zebrafish endothelium in vivo. We anticipate that this approach will facilitate multiplexed nanotube imaging in biomedical applications while enabling deep-tissue optical penetration, and single-molecule resolution in vivo. PMID:26387482

  11. Enzyme-catalyzed oxidation facilitates the return of fluorescence for single-walled carbon nanotubes.

    Science.gov (United States)

    Chiu, Cheuk Fai; Barth, Brian A; Kotchey, Gregg P; Zhao, Yong; Gogick, Kristy A; Saidi, Wissam A; Petoud, Stéphane; Star, Alexander

    2013-09-11

    In this work, we studied enzyme-catalyzed oxidation of single-walled carbon nanotubes (SWCNTs) produced by the high-pressure carbon monoxide (HiPco) method. While oxidation via strong acids introduced defect sites on SWCNTs and suppressed their near-infrared (NIR) fluorescence, our results indicated that the fluorescence of SWCNTs was restored upon enzymatic oxidation, providing new evidence that the reaction catalyzed by horseradish peroxidase (HRP) in the presence of H2O2 is mainly a defect-consuming step. These results were further supported by both UV-vis-NIR and Raman spectroscopy. Therefore, when acid oxidation followed by HRP-catalyzed enzyme oxidation was employed, shortened (applications in cellular NIR imaging and drug delivery systems. PMID:23672715

  12. A sensitive fluorescent sensor for selective determination of dichlorvos based on the recovered fluorescence of carbon dots-Cu(II) system.

    Science.gov (United States)

    Hou, Juying; Dong, Guangjuan; Tian, Zhengbin; Lu, Jiutian; Wang, Qianqian; Ai, Shiyun; Wang, Minglin

    2016-07-01

    In this paper, a simple and sensitive fluorescent sensor for dichlorvos was first constructed based on carbon dots-Cu(II) system. These carbon dots were obtained by simple hydrothermal reaction of feather. The fluorescence of these carbon dots can be selectively quenched by Cu(2+) ion. When acetylcholinesterase and acetylthiocholine were introduced into the system, thiocholine came into being, which can react with Cu(2+) ion and restore the fluorescence of the system. The reaction mechanism between Cu(2+) ion and thiocholine was confirmed by X-ray photoelectron spectroscopy. As one kind of acetylcholinesterase inhibitor, organophosphorus pesticides can be detected based on this sensing system. As an example of organophosphorus pesticides, dichlorvos was detected with a linear range of 6.0×10(-9)-6.0×10(-8)M. This sensing system has been successfully used for the analysis of cabbage and fruit juice samples. PMID:26920268

  13. Fluorescent carbon nanoparticles: A low-temperature trypsin-assisted preparation and Fe(3+) sensing.

    Science.gov (United States)

    Feng, Jie; Chen, Yonglei; Han, Yangxia; Liu, Juanjuan; Ren, Cuiling; Chen, Xingguo

    2016-07-01

    In recent years, extensive researches are focused on the fluorescent carbon nanoparticles (CNPs) due to their excellent photochemical, biocompatible and water-soluble properties. However, these synthesis methods are generally suffered from tedious processes. In this paper, fluorescent carbon nanoparticles are synthesized by a facile, one-pot, low-temperature method with trypsin and dopamine as precursors. The synthesis process avoids any heating operation and organic solvent, which provides a "green" and effective preparation route. The obtained CNPs exhibit excellent water-solubility, salt-tolerance and photostability. Based on the synergistic action of the inner filter effect and static quenching mechanism, the CNPs are exploited as a "turn-off" fluorescence sensor for sensitive and selective detection of Fe(3+) ions. The probe shows a wide linear range from 0.1 to 500 μM, with a limit of detection of 30 nM. Furthermore, the as-fabricated fluorescent sensing system is successfully applied to the analysis of Fe(3+) in biological samples such as human urine and serum samples with satisfactory recoveries (92.8-113.3%). PMID:27216399

  14. Airborne intercomparison of vacuum ultraviolet fluorescence and tunable diode laser absorption measurements of tropospheric carbon monoxide

    OpenAIRE

    Holloway, J.; Jakoubek, R.; Parrish, D.; C. Gerbig; A. Volz-Thomas; Schmitgen, S.; Fried, A.; Wert, B; Henry, B; Drummond, J.

    2000-01-01

    During the fall 1997 North Atlantic Regional Experiment (NARE 97), two separate intercomparisons of aircraft-based carbon monoxide measurement instrumentation were conducted. On September 2, CO measurements were simultaneously made aboard the National Oceanic and Atmospheric Administration (NOAA) WP-3 by vacuum ultraviolet (VUV) fluorescence and by tunable diode laser absorption spectroscopy (TDLAS), On September 18, an intercomparison flight was conducted between two separate instruments, bo...

  15. Multi-functional fluorescent carbon dots with antibacterial and gene delivery properties

    OpenAIRE

    Dou, Q; Fang, X.; S. Jiang; Chee, P. L.; Lee, T-C; Loh, X. J.

    2015-01-01

    Glucose is abundant in nature and can be found in various sources. In this study, we developed multifunctional carbon dots (CDs) with glucose, and poly(ethyleneimine) (PEI) which were further quaternized using a facile approach. The CDs are designed to possess both antibacteria and gene delivery capabilities. The inherent property was characterized with TEM, NMR, FTIR and fluorescent spectroscopy. Antibacterial activity was evaluated with Broth minimum inhibitory concentration (MIC) ass...

  16. Economical and green synthesis of bagasse-derived fluorescent carbon dots for biomedical applications

    International Nuclear Information System (INIS)

    Carbon quantum dots (CDs) are promising nanomaterials in biomedical, photocatalytical and photoelectronic applications. However, determining how to explore an ideal precursor for a renewable carbon resource is still an interesting challenge. Here, for the first time, we report that renewable wastes of bagasse as a new precursor were prepared for fluorescent CDs by a hydrothermal carbonization (HTC) process. The characterization results show that such bagasse-derived CDs are monodispersed, contain quasi spherical particles with a diameter of about 1.8 nm and exhibit favorable photoluminescence properties, super-high photostability and good dispersibility in water. Most importantly, bagasse-derived CDs have good biocompatibility and can be easily and quickly internalized by living cancer cells; they can also be used for multicolour biolabeling and bioimaging in cancer cells. It is suggested that bagasse-derived CDs might have potential applications in biomedical and photoelectronic fields. (paper)

  17. Functional long circulating single walled carbon nanotubes for fluorescent/photoacoustic imaging-guided enhanced phototherapy.

    Science.gov (United States)

    Xie, Lisi; Wang, Guohao; Zhou, Hao; Zhang, Fan; Guo, Zhide; Liu, Chuan; Zhang, Xianzhong; Zhu, Lei

    2016-10-01

    Nanotherapeutics have been investigated for years, but only modest survival benefits were observed clinic. This is partially attributed to the short and rapid elimination of nanodrug after intravenous administration. In this study, a long circulation single wall carbon nanotube (SWCNT) complex was successfully fabricated through a new SWCNT dispersion agent, evans blue (EB). The complex was endowed with fluorescent imaging and photodynamic therapy ability by self-assembly loading an albumin coupled fluorescent photosensitizer, Chlorin e6 (Ce6) via the high affinity between EB and albumin. The yielding multifunctional albumin/Ce6 loaded EB/carbon nanotube-based delivery system, named ACEC, is capable of providing fluorescent and photoacoustic imaging of tumors for optimizing therapeutic time window. Synergistic photodynamic therapy (PDT) and photothermal therapy (PTT) were carried out as guided by imaging results at 24 h post-injection and achieved an efficient tumor ablation effect. Compared to PDT or PTT alone, the combined phototherapy managed to damage tumor and diminish tumor without recurrence. Overall, our study presents a SWCNT based theranostic system with great promising in dual modalities imaging guided PTT/PDT combined treatment of tumor. The applications of EB on SWCNT functionalization can be easily extended to the other nanomaterials for improving their in vivo stability and circulation time. PMID:27392290

  18. Living Colors in the Gray Mold Pathogen Botrytis cinerea: Codon-Optimized Genes Encoding Green Fluorescent Protein and mCherry, Which Exhibit Bright Fluorescence▿

    OpenAIRE

    Leroch, Michaela; Mernke, Dennis; Koppenhoefer, Dieter; Schneider, Prisca; Mosbach, Andreas; Doehlemann, Gunther; Hahn, Matthias

    2011-01-01

    The green fluorescent protein (GFP) and its variants have been widely used in modern biology as reporters that allow a variety of live-cell imaging techniques. So far, GFP has rarely been used in the gray mold fungus Botrytis cinerea because of low fluorescence intensity. The codon usage of B. cinerea genes strongly deviates from that of commonly used GFP-encoding genes and reveals a lower GC content than other fungi. In this study, we report the development and use of a codon-optimized versi...

  19. Fluorescent carbon dots for sensitive determination and intracellular imaging of zinc(II) ion

    International Nuclear Information System (INIS)

    We describe the preparation of carbon dots (CDs) from glucose that possess high stability, a quantum yield of 0.32, and low toxicity (according to an MTT assay). They were used, in combination with the fluorogenic zinc(II) probe quercetin to establish a fluorescence resonance energy transfer (FRET) system for the determination of Zn(II). The CDs are acting as the donor, and the quercetin-Zn(II) complex as the acceptor. This is possible because of the strong overlap between the fluorescence spectrum of CDs and the absorption spectrum of the complex. The method enables Zn(II) to be determined in the 2 to 100 μM concentration range, with a 2 μM detection limit. The method was applied to image the distribution of Zn(II) ions in HeLa cells. (author)

  20. Fluorescent Comparison of Sr2CeO4 Prepared from Carbonate and Oxalate Precursor

    Institute of Scientific and Technical Information of China (English)

    石士考; 栗俊敏; 王继业; 王瑞芬; 周济

    2004-01-01

    A blue-emitting phosphor powder, Sr2CeO4, was synthesized after heat-treatment to carbonate and oxalate precursors, which were obtained by co-precipitation reactions with respective ammonium compounds as precipitants. The phase formation and chemical purity of Sr2CeO4 powders were studied on XRD, TGA and XPS techniques. Their fluorescent performances were investigated and compared. The photoluminescence emission spectra for the phosphor prepared from respective precursors are similar, having a broad band with the peak at about 470 nm. However, their fluorescent intensities are different after heat-treatment at same conditions. The optimum condition to achieve superior Sr2CeO4 phosphor is confirmed.

  1. Synthesis of highly fluorescent hydrophobic carbon dots by hot injection method using Paraplast as precursor

    International Nuclear Information System (INIS)

    We have reported synthesis of bright blue colored hydrophobic carbon dots (hC-dots) using highly pure blend of polymers called Paraplast. We developed a hot injection method for making nearly monodispersed hC-dots with a diameter in a range: 5–30 nm as confirmed by high resolution transmission electron microscopy (HRTEM). The involvement of various functional groups was confirmed by Fourier transform infra-red (FTIR) spectroscopy. These hC-dots were incubated with breast cancer stem cells in order to check the entry as well as biological imaging. The cells were analyzed using epifluorescent microscopy. hC-dots showed concentration dependent cytotoxicity (LD50: 50 mg/ml) and could be used for bioimaging even at lower concentration (0.5 mg/ml). hC-dots were found to be versatile agents for peeping inside the cells which could also be used for delivery of water insoluble chemotherapeutic agents to variety of solid tumors. - Highlights: • Synthesis of hydrophobic carbon dots from polymer based Paraplast • Deep blue color under the influence of UV light • Typical optical properties used for biological imaging • Biological imaging of breast cancer stem cells revealing potential of carbon dots

  2. Synthesis of highly fluorescent hydrophobic carbon dots by hot injection method using Paraplast as precursor

    Energy Technology Data Exchange (ETDEWEB)

    Talib, Abou [Doctoral Degree Program in Marine Biotechnology, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China); Pandey, Sunil [Department of Chemistry, National Sun Yat-Sen University, 70, Lien-Hai Road, Kaohsiung 80424, Taiwan (China); Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, 70, Lien-Hai Road, Kaohsiung 80424, Taiwan (China); Thakur, Mukeshchand [Department of Chemistry, National Sun Yat-Sen University, 70, Lien-Hai Road, Kaohsiung 80424, Taiwan (China); Wu, Hui-Fen, E-mail: hui@faculty.nsysu.edu.tw [Department of Chemistry, National Sun Yat-Sen University, 70, Lien-Hai Road, Kaohsiung 80424, Taiwan (China); Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, 70, Lien-Hai Road, Kaohsiung 80424, Taiwan (China); Doctoral Degree Program in Marine Biotechnology, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China); School of Pharmacy, College of Pharmacy, Kaohsiung Medical University, Kaohsiung 800, Taiwan (China); Institute of Medical Science and Technology, National Sun Yat-Sen University, Kaohsiung, 80424, Taiwan (China)

    2015-03-01

    We have reported synthesis of bright blue colored hydrophobic carbon dots (hC-dots) using highly pure blend of polymers called Paraplast. We developed a hot injection method for making nearly monodispersed hC-dots with a diameter in a range: 5–30 nm as confirmed by high resolution transmission electron microscopy (HRTEM). The involvement of various functional groups was confirmed by Fourier transform infra-red (FTIR) spectroscopy. These hC-dots were incubated with breast cancer stem cells in order to check the entry as well as biological imaging. The cells were analyzed using epifluorescent microscopy. hC-dots showed concentration dependent cytotoxicity (LD{sub 50}: 50 mg/ml) and could be used for bioimaging even at lower concentration (0.5 mg/ml). hC-dots were found to be versatile agents for peeping inside the cells which could also be used for delivery of water insoluble chemotherapeutic agents to variety of solid tumors. - Highlights: • Synthesis of hydrophobic carbon dots from polymer based Paraplast • Deep blue color under the influence of UV light • Typical optical properties used for biological imaging • Biological imaging of breast cancer stem cells revealing potential of carbon dots.

  3. Preparation and Fluorescence Resonance Energy Transfer of Carbon Dots%碳点的制备及其荧光共振能量转移

    Institute of Scientific and Technical Information of China (English)

    张煌博; 曹学功; 孙向英

    2014-01-01

    Amino-modified carbon dots were synthesized by the low temperature carbonization of citric acid in the pres-ence of branched polyethylenimine in one step.The bright blue emission was observed under the excitation of ultraviolet rays.Fourier transform infrared spectroscopy and X-ray powder diffraction were used to characterize its structure.Mean-while,the fluorescence resonance energy transfer between amino-modified carbon dots and CdTe QDs in liquid or solid-liquid phase was studied.The results show that fluorescence resonance energy transfer efficiency in liquid is much larger than the solid-liquid phase and it also has a limit.%以枝状聚乙烯亚胺和柠檬酸为原料,低温熔融法一步合成水溶性的氨基化碳点,碳点在紫外光激发下发出明亮的蓝光。采用傅里叶变换红外光谱和 X 射线粉末衍射仪对其结构进行表征,并研究其与碲化镉量子点在液相和固液界面的荧光共振能量转移。实验结果表明:液相中的荧光共振能量转移效率远大于固液界面的荧光共振能量转移,且能量转移具有一定的限度。

  4. Determination of carbon in natural freshwater biofilms with total reflection X-ray fluorescence spectrometry

    International Nuclear Information System (INIS)

    There is a growing interest in determination of low Z elements, i.e., carbon to phosphorus, in biological samples. Total reflection X-ray fluorescence spectrometry (TXRF) has been already established as suitable trace element analytical method with low sample demand and quite good quantification limits. Recently, the determinable element range was extended towards Z = 6 (carbon). Biofilms can be used for biomonioring purposes in the aquatic environment. Besides the trace metals, especially the determination of the carbon content is important for the better understanding of the early stage of biofilm formation. For this, an ATI low Z spectrometer equipped with Cr-anode X-ray tube, multilayer monochromator, vacuum chamber, and a Si(Li) detector with ultra thin window was used. Biofilms were grown on two different artificial supports (granite and plexiglass), freeze dried, suspended in high purity water and analyzed. As an internal standard the natural titanium content of the biofilms was used. The accuracy of the method was checked by total carbon measurement using a combusting carbon analyzer.

  5. Graphitic carbon nitride nanosheet-based multicolour fluorescent nanoprobe for multiplexed analysis of DNA

    International Nuclear Information System (INIS)

    We demonstrate that nanosheets composed of graphitic carbon nitride (g-C3N4) can serve as a low-cost and efficient fluorescent nanoprobe for the multiplexed detection of DNA in solution. The strategy is based on the finding that g-C3N4 is capable of binding dye-labeled single-stranded DNA (ssDNA) which results in quenching of the fluorescence of the dye. If target DNA hybridizes with dye-labeled ssDNA, the interaction between dye-labeled ssDNA and g-C3N4 is weakened, and this results in desorption of the dsDNA from the surface of the g-C3N4 and in recovery of fluorescence. The large surface area of g-C3N4 nanosheets allows for simultaneous quenching of multicolor DNA probes labeled with different dyes, leading to the development of multiplexed DNA sensors for the detection of multiple DNA targets in a single solution. By using one 15-mer DNA fragment and one 18-mer DNA fragment as proof-of-principle analytes, the method displayed good analytical performance. The limits of detection are 75 and 62 pM, respectively. The method is simple and sensitive, and was used to detect DNA in serum samples. We perceive that this method represents a new approach towards multiplexed assays for applications in DNA monitoring, clinical diagnosis, and in the detection of genetic disorders. (author)

  6. Synthesis and Characterisation of Fluorescent Carbon Nanodots Produced in Ionic Liquids by Laser Ablation.

    Science.gov (United States)

    Castro, Hemerson P S; Souza, Virgínia S; Scholten, Jackson D; Dias, Janine H; Fernandes, Jesum A; Rodembusch, Fabiano S; Dos Reis, Roberto; Dupont, Jairton; Teixeira, Sérgio R; Correia, Ricardo R B

    2016-01-01

    Carbon nanodots (C-dots) with an average size of 1.5 and 3.0 nm were produced by laser ablation in different imidazolium ionic liquids (ILs), namely, 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMI.BF4 ), 1-n-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMI.NTf2 ) and 1-n-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (OMI.NTf2 ). The mean size of the nanoparticles is influenced by the imidazolium alkyl side chain but not by the nature of the anion. However, by varying the anion (BF4 vs. NTf2 ) it was possible to detect a significant modification of the fluorescence properties. The C-dots are much probably stabilised by an electrostatic layer of the IL and this interaction has played an important role with regard to the formation, stabilisation and photoluminescence properties of the nanodots. A tuneable broadband fluorescence emission from the colloidal suspension was observed under ultraviolet/visible excitation with fluorescence lifetimes fitted by a multi-exponential decay with average values around 7 ns. PMID:26558445

  7. Fluorescent carbon quantum dot hydrogels for direct determination of silver ions.

    Science.gov (United States)

    Cayuela, A; Soriano, M L; Kennedy, S R; Steed, J W; Valcárcel, M

    2016-05-01

    The paper reports for the first time the direct determination of silver ion (Ag(+)) using luminescent Carbon Quantum Dot hydrogels (CQDGs). Carbon Quantum Dots (CQDs) with different superficial moieties (passivate-CQDs with carboxylic groups, thiol-CQDs and amine-CQDs) were used to prepare hybrid gels using a low molecular weight hydrogelator (LMWG). The use of the gels results in considerable fluorescence enhancement and also markedly influences selectivity. The most selective CQDG system for Ag(+) ion detection proved to be those containing carboxylic groups onto their surface. The selectivity towards Ag(+) ions is possibly due to its flexible coordination sphere compared with other metal ions. This fluorescent sensing platform is based on the strong Ag-O interaction which can quench the photoluminescence of passivate-CQDs (p-CQDs) through charge transfer. The limit of detection (LOD) and quantification (LOQ) of the proposed method were 0.55 and 1.83µgmL(-1), respectively, being applied in river water samples. PMID:26946015

  8. A facile and green method towards coal-based fluorescent carbon dots with photocatalytic activity

    Science.gov (United States)

    Hu, Shengliang; Wei, Zhijia; Chang, Qing; Trinchi, Adrian; Yang, Jinlong

    2016-08-01

    One of the most widely used methods for exfoliating crystalline nanocarbon is via strong oxidizing acid treatment of bulk carbon sources, such as graphite, carbon black and coal. Not only is such method dangerous and accompanied by the liberation of toxic gases, it is also plagued by issues of purity, requiring the thorough and costly removal of the excess oxidizing acids and salts formed during the process. Herein we report a facile, green and inexpensive top-down strategy towards fluorescent carbon dots (CDs) from coal without incurring the burden of tedious or inefficient post-processing steps and facing the danger of highly toxic gas liberation. The presented approach shows a high yield and great potential for carbon dot production scale-up using coal, one of our most abundant and low-cost resources. The prepared CDs demonstrate photocatalytic behavior capable of rapidly degrading organic dyes under visible light. Our findings may lead to alternative uses of coal, particularly for applications including the treatment of environmental pollution, solar energy conversion or storage, and highlight coal's applicability in areas other than energy producing via burning of this great resource.

  9. Microwave assisted one-step green synthesis of fluorescent carbon nanoparticles from ionic liquids and their application as novel fluorescence probe for quercetin determination

    International Nuclear Information System (INIS)

    In this study, a new sensitive and convenient method for the determination of quercetin based on the fluorescence quenching of fluorescent carbon nanoparticles (CNPs) was developed. The CNPs derived from ionic liquids were prepared using a green and rapid microwave-assisted synthetic approach for the first time. The one-step green preparation process is simple and effective, neither a strong acid solvent nor surface modification reagent is needed, which makes this approach very suitable for large-scale production. The prepared CNPs were characterized by high-resolution transmission electron microscopy, Fourier transform infrared spectrometry, elemental analysis and spectrofluorometry. In NH3–NH4Cl buffer solution (pH 9.47), the fluorescence signals of CNPs decreased obviously with increase of the quercetin concentration. The effect of other coexisting foreign substances on the intensity of CNPs showed a low interference response. Under the optimum conditions, the fluorescence intensity presented a linear response versus quercetin concentration according to the Stern–Volmer equation with an excellent 0.9989 correlation coefficient. The linearity ranged from 2.87×10−6 to 31.57×10−6 mol L−1 with the detection limit (3σ) of 9.88×10−8 mol L−1. The recovery of this method was in the range of 93.3–105.1%. Therefore, the CNPs could to be a promising candidate as a fluorescence probe for the detection of trace levels of quercetin due to their advantages in low-cost production, low cytotoxicity, strong fluorescence and excellent biocompatibility. -- Highlights: ► Fluorescent CNPs were synthesized with microwave pyrolysis approach. ► Ionic liquids were used as sources of carbon and nitrogen for the first time. ► The formation and functionalization of CNPs were accomplished simultaneously. ► CNPs were used as fluorescent probes for the determination of quercetin. ► A sensitive and convenient method based on the fluorescence quenching was developed

  10. Microwave assisted one-step green synthesis of fluorescent carbon nanoparticles from ionic liquids and their application as novel fluorescence probe for quercetin determination

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Deli; Yuan, Danhua [Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009 (China); He, Hua, E-mail: dochehua@163.com [Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009 (China); Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, China Pharmaceutical University, Nanjing 210009 (China); Gao, Mengmeng [Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009 (China)

    2013-08-15

    In this study, a new sensitive and convenient method for the determination of quercetin based on the fluorescence quenching of fluorescent carbon nanoparticles (CNPs) was developed. The CNPs derived from ionic liquids were prepared using a green and rapid microwave-assisted synthetic approach for the first time. The one-step green preparation process is simple and effective, neither a strong acid solvent nor surface modification reagent is needed, which makes this approach very suitable for large-scale production. The prepared CNPs were characterized by high-resolution transmission electron microscopy, Fourier transform infrared spectrometry, elemental analysis and spectrofluorometry. In NH{sub 3}–NH{sub 4}Cl buffer solution (pH 9.47), the fluorescence signals of CNPs decreased obviously with increase of the quercetin concentration. The effect of other coexisting foreign substances on the intensity of CNPs showed a low interference response. Under the optimum conditions, the fluorescence intensity presented a linear response versus quercetin concentration according to the Stern–Volmer equation with an excellent 0.9989 correlation coefficient. The linearity ranged from 2.87×10{sup −6} to 31.57×10{sup −6} mol L{sup −1} with the detection limit (3σ) of 9.88×10{sup −8} mol L{sup −1}. The recovery of this method was in the range of 93.3–105.1%. Therefore, the CNPs could to be a promising candidate as a fluorescence probe for the detection of trace levels of quercetin due to their advantages in low-cost production, low cytotoxicity, strong fluorescence and excellent biocompatibility. -- Highlights: ► Fluorescent CNPs were synthesized with microwave pyrolysis approach. ► Ionic liquids were used as sources of carbon and nitrogen for the first time. ► The formation and functionalization of CNPs were accomplished simultaneously. ► CNPs were used as fluorescent probes for the determination of quercetin. ► A sensitive and convenient method based

  11. Synthesis of fluorescent carbon dots via microwave carbonization of citric acid in presence of tetraoctylammonium ion, and their application to cellular bioimaging

    International Nuclear Information System (INIS)

    A jelly-like form of carbon dots (C-dots) was prepared by microwave-assisted synthesis from citric acid in the presence of tetraoctylammonium bromide. The effect of the concentration of tetraoctylammonium bromide was examined. The synthesized carbon dots were characterized by UV–vis, XRD, FTIR, fluorescence and HR-TEM. Fluorescence extends from 350 to 600 nm, and the corresponding excitation wavelengths range from 300 to 460 nm. Quantum yields are at around 0.11. A cytotoxicity study showed carbon dots to be cell permeable and biocompatible which renders them appropriate for imaging applications. The dots were used to image HeLa cell lines via the blue fluorescence of the dots. (author)

  12. Ratiometric fluorescent paper sensor utilizing hybrid carbon dots-quantum dots for the visual determination of copper ions

    Science.gov (United States)

    Wang, Yahui; Zhang, Cheng; Chen, Xiaochun; Yang, Bo; Yang, Liang; Jiang, Changlong; Zhang, Zhongping

    2016-03-01

    A simple and effective ratiometric fluorescence nanosensor for the selective detection of Cu2+ has been developed by covalently connecting the carboxyl-modified red fluorescent cadmium telluride (CdTe) quantum dots (QDs) to the amino-functionalized blue fluorescent carbon nanodots (CDs). The sensor exhibits the dual-emissions peaked at 437 and 654 nm, under a single excitation wavelength of 340 nm. The red fluorescence can be selectively quenched by Cu2+, while the blue fluorescence is a internal reference, resulting in a distinguishable fluorescence color change from pink to blue under a UV lamp. The detection limit of this highly sensitive ratiometric probe is as low as 0.36 nM, which is lower than the U.S. Environmental Protection Agency (EPA) defined limit (20 μM). Moreover, a paper-based sensor has been prepared by printing the hybrid carbon dots-quantum dots probe on a microporous membrane, which provides a convenient and simple approach for the visual detection of Cu2+. Therefore, the as-synthesized probe shows great potential application for the determination of Cu2+ in real samples.A simple and effective ratiometric fluorescence nanosensor for the selective detection of Cu2+ has been developed by covalently connecting the carboxyl-modified red fluorescent cadmium telluride (CdTe) quantum dots (QDs) to the amino-functionalized blue fluorescent carbon nanodots (CDs). The sensor exhibits the dual-emissions peaked at 437 and 654 nm, under a single excitation wavelength of 340 nm. The red fluorescence can be selectively quenched by Cu2+, while the blue fluorescence is a internal reference, resulting in a distinguishable fluorescence color change from pink to blue under a UV lamp. The detection limit of this highly sensitive ratiometric probe is as low as 0.36 nM, which is lower than the U.S. Environmental Protection Agency (EPA) defined limit (20 μM). Moreover, a paper-based sensor has been prepared by printing the hybrid carbon dots-quantum dots probe on a

  13. Photoluminescence sidebands of carbon nanotubes below the bright singlet excitonic levels: Coupling between dark excitons and K-point phonons

    OpenAIRE

    Murakami, Yoichi; Lu, Benjamin; Kazaoui, Said; Minami, Nobutsugu; Okubo, Tatsuya; Maruyama, Shigeo

    2008-01-01

    We performed detailed photoluminescence (PL) spectroscopy studies of three different types of single-walled carbon nanotubes (SWNTs) by using samples that contain essentially only one chiral type of SWNT, (6,5), (7,5), or (10,5). The observed PL spectra unambiguously show the existence of an emission sideband at ~ 145 meV below the lowest singlet excitonic (E11) level, whose identity and origin are now under debate. We find that the energy separation between the E11 level and the sideband is ...

  14. Prospects for Chlorophyll Fluorescence Remote Sensing from the Orbiting Carbon Observatory-2

    Science.gov (United States)

    Frankenberg, Christian; Odell, Chris; Berry, Joseph; Guanter, Luis; Joiner, Joanna; Kohler, Philipp; Pollock, Randy; Taylor, Thomas E.

    2014-01-01

    The Orbiting Carbon Observatory-2 (OCO-2), scheduled to launch in July 2014, is a NASA mission designed to measure atmospheric CO2. Its main purpose is to allow inversions of net flux estimates of CO2 on regional to continental scales using the total column CO2 retrieved using high-resolution spectra in the 0.76, 1.6, and 2.0 nm ranges. Recently, it was shown that solar-induced chlorophyll fluorescence (SIF), a proxy for gross primary production (GPP, carbon uptake through photosynthesis), can be accurately retrieved from space using high spectral resolution radiances in the 750 nm range from the Japanese GOSAT and European GOME-2 instruments. Here, we use real OCO-2 thermal vacuum test data as well as a full repeat cycle (16 days) of simulated OCO-2 spectra under realistic conditions to evaluate the potential of OCO-2 for retrievals of chlorophyll fluorescence and also its dependence on clouds and aerosols. We find that the single-measurement precision is 0.3-0.5 Wm(exp -2)sr(exp -1) nm(exp -1) (15-25% of typical peak values), better than current measurements from space but still difficult to interpret on a single-sounding basis. The most significant advancement will come from smaller ground-pixel sizes and increased measurement frequency, with a 100-fold increase compared to GOSAT (and about 8 times higher than GOME-2). This will largely decrease the need for coarse spatial and temporal averaging in data analysis and pave the way to accurate local studies.We also find that the lack of full global mapping from the OCO-2 only incurs small representativeness errors on regional averages. Eventually, the combination of net ecosystem exchange (NEE) derived from CO2 source/sink inversions and SIF as proxy for GPP from the same satellite will provide a more process-based understanding of the global carbon cycle.

  15. Green synthesis of carbon nanodots as an effective fluorescent probe for sensitive and selective detection of mercury(II) ions

    Energy Technology Data Exchange (ETDEWEB)

    Lu Wenbo; Qin Xiaoyun [China West Normal University, Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, School of Chemistry and Chemical Industry (China); Asiri, Abdullah M.; Al-Youbi, Abdulrahman O. [King Abdulaziz University, Chemistry Department, Faculty of Science (Saudi Arabia); Sun Xuping, E-mail: sunxp@ciac.jl.cn [China West Normal University, Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, School of Chemistry and Chemical Industry (China)

    2013-01-15

    The present communication reports on the use of sweet potatoes as carbon source for green synthesis of fluorescent carbon nanodots (CNDs) ranging from 1 to 3 nm. We further demonstrate the use of such CNDs as a very effective fluorescent probe for label-free, sensitive, and selective detection of Hg{sup 2+} with a detection limit as low as 1 nM. The feasibility of the CNDs for analysis of Hg{sup 2+} in a real water sample is also demonstrated successfully.Graphical Abstract.

  16. Development of TEM and SEM high brightness electron guns using cold-field emission from a carbon nanotip

    International Nuclear Information System (INIS)

    A newly developed carbon cone nanotip (CCnT) has been used as field emission cathode both in low voltage SEM (30 kV) electron source and high voltage TEM (200 kV) electron source. The results clearly show, for both technologies, an unprecedented stability of the emission and the probe current with almost no decay during 1 h, as well as a very small noise (rms less than 0.5%) compared to standard sources which use tungsten tips as emitting cathode. In addition, quantitative electric field mapping around the FE tip have been performed using in situ electron holography experiments during the emission of the new tip. These results show the advantage of the very high aspect ratio of the new CCnT which induces a strong enhancement of the electric field at the apex of the tip, leading to very small extraction voltage (some hundred of volts) for which the field emission will start. The combination of these experiments with emission current measurements has also allowed to extract an exit work function value of 4.8 eV. - Highlights: • We develop a new field emission cathode based on carbon material. • We determine the exit work function of this new cathode using a combination of in situ electron holography and finite element modeling. • We show that the stability of cold-field emitted current can be improved with no decay during one hour of emission with a lower emission noise (less than 0.5%). • We used this cathode both for 200 kV TEM and 30 kV SEM cold field emission source. • As a TEM source, we also observe an increase of the spatial coherence using Fresnel fringes contrast

  17. Development of TEM and SEM high brightness electron guns using cold-field emission from a carbon nanotip

    Energy Technology Data Exchange (ETDEWEB)

    Houdellier, F.; Knoop, L. de; Gatel, C.; Masseboeuf, A. [CEMES-CNRS, 29 Rue Jeanne Marvig, 31055 Toulouse (France); Mamishin, S.; Taniguchi, Y. [Hitachi High-Technologies Corporation, 882, Ichige, Hitachinaka, Ibaraki 312-8504 (Japan); Delmas, M.; Monthioux, M.; Hÿtch, M.J.; Snoeck, E. [CEMES-CNRS, 29 Rue Jeanne Marvig, 31055 Toulouse (France)

    2015-04-15

    A newly developed carbon cone nanotip (CCnT) has been used as field emission cathode both in low voltage SEM (30 kV) electron source and high voltage TEM (200 kV) electron source. The results clearly show, for both technologies, an unprecedented stability of the emission and the probe current with almost no decay during 1 h, as well as a very small noise (rms less than 0.5%) compared to standard sources which use tungsten tips as emitting cathode. In addition, quantitative electric field mapping around the FE tip have been performed using in situ electron holography experiments during the emission of the new tip. These results show the advantage of the very high aspect ratio of the new CCnT which induces a strong enhancement of the electric field at the apex of the tip, leading to very small extraction voltage (some hundred of volts) for which the field emission will start. The combination of these experiments with emission current measurements has also allowed to extract an exit work function value of 4.8 eV. - Highlights: • We develop a new field emission cathode based on carbon material. • We determine the exit work function of this new cathode using a combination of in situ electron holography and finite element modeling. • We show that the stability of cold-field emitted current can be improved with no decay during one hour of emission with a lower emission noise (less than 0.5%). • We used this cathode both for 200 kV TEM and 30 kV SEM cold field emission source. • As a TEM source, we also observe an increase of the spatial coherence using Fresnel fringes contrast.

  18. Consistent space-based retrievals of chlorophyll fluorescence and atmospheric CO2 and CH4 for improved estimates of carbon fluxes

    OpenAIRE

    Hahne, Philipp

    2015-01-01

    Understanding the natural carbon cycle and its feedback to climate change requires atmospheric carbon observations to constrain carbon surface fluxes. The retrieval method RemoTeC uses satellite measurements to retrieve atmospheric CO2 and CH4. This work improves the retrieval such that it accounts for chlorophyll fluorescence. Furthermore, this work shows that the CO2 retrieval accounting for chlorophyll fluorescence provides observational constraints on carbon surface flux estimates.

  19. One-pot synthesis of water-dispersible Ag2S quantum dots with bright fluorescent emission in the second near-infrared window

    International Nuclear Information System (INIS)

    The second near-infrared window (NIR-II, wavelength of 1.0–1.4 μm) is optimal for the bioimaging of live animals due to their low albedo and endogenous autofluorescence. Herein, we report a facile and one-pot biomimetic synthesis approach to prepare water-dispersible NIR-II-emitting ultrasmall Ag2S quantum dots (QDs). Photoluminescence spectra showed that the emission peaks could be tuned from 1294 to 1050 nm as the size of the Ag2S QDs varied from 6.8 to 1.6 nm. The x-ray diffraction patterns and x-ray photoelectron spectra confirmed that the products were monoclinic α-Ag2S. Fourier transform infrared spectrograph analysis indicated that the products were protein-conjugated Ag2S QDs. Examination of cytotoxicity and the hemolysis test showed that the obtained Ag2S QDs had good biocompatibility, indicating that such a nanomaterial could be a new kind of fluorescent label for in vivo imaging. (paper)

  20. Far-ultraviolet fluorescence of carbon monoxide in the red giant Arcturus

    International Nuclear Information System (INIS)

    We present evidence that many of the weak features observed with the International Ultraviolet Explorer (IUE) in the far-ultraviolet (1150--2000 A) spectrum of the archetype red giant Arcturus (K2 III) are A--X fourth positive bands of carbon monoxide excited by chromospheric emissions of O I, C I, and H I. The appearance of fluorescent CO bands near the wavelengths of commonly used indicators of high-temperature (T>2 x 104 K) plasma, such as C II lambda1335 and C IV lambda1548, introduces a serious ambiguity in diagnosing the presence of hot material in the outer atmospheres of the cool giants by means of low-dispersion IUE spectra

  1. Versatile visualization of individual single-walled carbon nanotubes with near-infrared fluorescence microscopy.

    Science.gov (United States)

    Tsyboulski, Dmitri A; Bachilo, Sergei M; Weisman, R Bruce

    2005-05-01

    Fluorescence microscopy in the near-infrared between 950 and 1600 nm has been developed as a novel method to image and study single-walled carbon nanotubes (SWNTs) in a variety of environments. Intrinsic photoluminescence of disaggregated pristine SWNTs was excited by a diode laser and detected with a two-dimensional InGaAs photodiode array. Individual nanotubes were visualized with a spatial resolution of ca. 1 microm and characterized with polarization measurements and emission spectroscopy. Spatially resolved emission spectra allowed (n,m) identification of single nanotubes and revealed small environmentally induced spectral shifts between segments of long tubes. Nanotube motions in aqueous surfactant were visualized with a time resolution of 50 ms and used to estimate the diffusion coefficient. PMID:15884905

  2. Probing Energy and Electron Transfer Mechanisms in Fluorescence Quenching of Biomass Carbon Quantum Dots.

    Science.gov (United States)

    Liang, Zicheng; Kang, Mijeong; Payne, Gregory F; Wang, Xiaohui; Sun, Runcang

    2016-07-13

    The recent discovery of biomass-derived carbon quantum dots (CQDs) offers the potential to extend the sensing and imaging capabilities of quantum dots (QDs) to applications that require biocompatibility and environmental friendliness. Many studies have confirmed the exciting optical properties of CQDs and suggested a range of applications, but realizing the potential of CQDs will require a deeper fundamental understanding of their photophysical behavior. Here, biomass-derived CQDs were synthesized by hydrothermal processing methods from the aminopolysaccharide chitosan, and their fluorescence quenching behaviors were investigated. A family of nitroaromatics with different ring substituents was used to generate systematically varying CQD-quenching behaviors. Experimental evidence including a correlation between quenching constant and spectral overlap, fluorescence lifetime decay, and donor-acceptor distance all demonstrate that the primary mechanism for QCD-quenching is Förster resonance energy transfer (FRET) and not electron transfer. Spectroelectrochemical studies with redox-dependent quenching molecules and studies with complex dye molecules further support this conclusion. We envision this fundamental understanding of CQDs will facilitate the application of these emerging nanomaterials for sensing and imaging. PMID:27314592

  3. Detection of Ag(+) using graphite carbon nitride nanosheets based on fluorescence quenching.

    Science.gov (United States)

    Bian, Wei; Zhang, Hao; Yu, Qing; Shi, Meijuan; Shuang, Shaomin; Cai, Zongwei; Choi, Martin M F

    2016-12-01

    The graphite carbon nitride (g-C3N4) nanosheets were synthesized and applied for the detection of Ag(+) ion in aqueous solutions. Transmission electron microscopy, Fourier infrared spectroscopy, x-ray diffraction, ultraviolet/visible and photoluminescence spectroscopy were used for characterization of g-C3N4 nanosheets. The fluorescence intensity of g-C3N4 nanosheets decreases with the increase in the concentration of Ag(+). The fluorescence probe can be applied for detection of Ag(+). The results show that it has high selectivity to Ag(+) and exhibits a good linearity over the concentration range 0.020-2.0μM with a detection limit of 27nM. Most cations do not have any interference on the detection of Ag(+). The quenching process is assessed and discussed. Finally, the g-C3N4 nanosheets have been successfully used for the detection of Ag(+) in real water samples. The recoveries of spiked water samples are >97%. PMID:27348047

  4. Field-scale fluorescence fingerprinting of biochar-borne dissolved organic carbon.

    Science.gov (United States)

    Uchimiya, Minori; Liu, Zhongzhen; Sistani, Karamat

    2016-03-15

    Biochar continues to receive worldwide enthusiasm as means of augmenting recalcitrant organic carbon in agricultural soils. Realistic biochar amendment rate (typically less than 1 wt%) in the field scale, and subsequent loss by sizing, rain, and other transport events demand reliable methods to quantify the remaining portions of amended biochar. This study employed fluorescence excitation-emission (EEM) spectrophotometry and parallel factor analysis (PARAFAC) to specifically target pyrogenic dissolved organic carbon (DOC) released by amended biochar during the course of a field trial at Bowling Green, KY experimental site. Toluene/methanol (1:6 v/v) extracts of surface (0-15 cm) soils amended with 21.28 t ha(-1) fast pyrolysis biochar afforded PARAFAC fingerprints representing different degrees of aromaticity. Compared to the control without treatments, biochar treatment (with and without poultry manure or chemical fertilizer) increased the relative contribution of PARAFAC fingerprint attributable to labile polyaromatic DOC structures. Poultry manure or chemical fertilizer alone (without biochar) did not influence the amounts of polyaromatic DOC structures. Existence of biochar could be further validated by the changes in %DOC (relative to the total carbon), fixed C content, and UV absorbance (360 nm), whereas FTIR, %O, and sorption of model agrochemical (deisopropylatrazine) did not reflect the presence of biochar in the soil samples. Developed toluene/methanol-based EEM-PARAFAC technique will provide a sensitive, rapid, and cost-competitive method to validate the long-term carbon sequestration by the biochar soil amendment. PMID:26751812

  5. Synthesis and energy transfer within carbon-based fluorescent rare earth nanoparticles and nanocomposites (Conference Presentation)

    Science.gov (United States)

    Yust, Brian G.; Chipara, Mircea; Saenz, Aaron

    2016-03-01

    Recently, there has been a great deal of interest in fluorescent and upconverting rare earth-based nanoparticles for biomedical imaging and photodynamic therapy applications. While many of the widely explored upconverting contrast agents are comprised of fluoride or oxide crystal structures, very little work has been done to investigate the up- and downconversion emission in rare earth-doped carbon nanocomposites. Of particular interest, graphene-UCNP nanocomposites and sesquicarbide nanoparticles may offer a wide range of new applications when coupled with the extraordinary optical properties of rare earth-doped systems, such as potential use as nano-transducers. Carbon-based nanocomposites and sesquicarbides doped with rare earth elements were synthesized using the microwave and solvothermal methods with additional brief high temperature heat treatments. They were then characterized by XRD, visible and NIR excitation and emission spectroscopy, as well as Raman spectrsocopy. Tuning of the emission manifold ratios was explored through different compositions and size. Also, energy transfer between the emitting ions and the electronic states of the host structure was explored. Finally, cytotoxicity was tested, and cellular uptake of these nanomaterials was performed with confocal microscopy.

  6. X-ray fluorescence analysis of strontium in environmental water by using barium carbonate coprecipitation method

    International Nuclear Information System (INIS)

    Determination of strontium in environmental water was studied by a coprecipitation method with barium carbonate and the subsequent X-ray fluorescence analysis. Fifty mg of barium ion and 1 g of sodium carbonate were added to sample water, which was then mixed for one hour by a magnetic stirrer. Precipitate was gathered onto a membrane filter paper to measure its XF intensity. The amount of strontium from 2 to 150 μg could be repeatedly determined by means of the calibration curve method, and the limit of detection was found to be 0.6 μg of strontium. A large amount of calcium and magnesium ions was found to interfere with the coprecipitation of strontium ion. However, this interference could be eliminated by using a small amount of sample water. Strontium in several environmental waters was determined by the above method. The results obtained from the calibration curve method and the standard addition method agreed with each other, and also agreed with those from the atomic absorption spectrometry. (author)

  7. Single Chirality (6,4) Single-Walled Carbon Nanotubes for Fluorescence Imaging with Silicon Detectors.

    Science.gov (United States)

    Antaris, Alexander L; Yaghi, Omar K; Hong, Guosong; Diao, Shuo; Zhang, Bo; Yang, Jiang; Chew, Leila; Dai, Hongjie

    2015-12-16

    Postsynthetic single-walled carbon nanotube (SWCNT) sorting methods such as density gradient ultracentrifugation, gel chromatography, and electrophoresis have all been inspired by established biochemistry separation techniques designed to separate subcellular components. Biochemistry separation techniques have been refined to the degree that parameters such as pH, salt concentration, and temperature are necessary for a successful separation, yet these conditions are only now being applied to SWCNT separation methodologies. Slight changes in pH produce radically different behaviors of SWCNTs inside a density gradient, allowing for the facile separation of ultrahigh purity (6,4) SWCNTs from as-synthesized carbon nanotubes. The (6,4) SWCNTs are novel fluorophores emitting below ≈900 nm and can be easily detected with conventional silicon-based charge-coupled device detectors without the need for specialized InGaAs cameras. The (6,4) SWCNTs are used to demonstrate their potential as a clinically relevant NIR-I fluorescence stain for the immunohistochemical staining of cells and cancer tissue sections displaying high endothelial growth factor receptor levels. PMID:26529611

  8. Label-Free Carbon-Dots-Based Ratiometric Fluorescence pH Nanoprobes for Intracellular pH Sensing.

    Science.gov (United States)

    Shangguan, Jingfang; He, Dinggeng; He, Xiaoxiao; Wang, Kemin; Xu, Fengzhou; Liu, Jinquan; Tang, Jinlu; Yang, Xue; Huang, Jin

    2016-08-01

    Measuring pH in living cells is of great importance for better understanding cellular functions as well as providing pivotal assistance for early diagnosis of diseases. In this work, we report the first use of a novel kind of label-free carbon dots for intracellular ratiometric fluorescence pH sensing. By simple one-pot hydrothermal treatment of citric acid and basic fuchsin, the carbon dots showing dual emission bands at 475 and 545 nm under single-wavelength excitation were synthesized. It is demonstrated that the fluorescence intensities of the as-synthesized carbon dots at the two emissions are pH-sensitive simultaneously. The intensity ratio (I475 nm/I545 nm) is linear against pH values from 5.2 to 8.8 in buffer solution, affording the capability as ratiometric probes for intracellular pH sensing. It also displays that the carbon dots show excellent reversibility and photostability in pH measurements. With this nanoprobe, quantitative fluorescence imaging using the ratio of two emissions (I475 nm/I545 nm) for the detection of intracellular pH were successfully applied in HeLa cells. In contrast to most of the reported nanomaterials-based ratiometric pH sensors which rely on the attachment of additional dyes, these carbon-dots-based ratiometric probes are low in toxicity, easy to synthesize, and free from labels. PMID:27334762

  9. Carbon dots-based fluorescent probe for "off-on" sensing of Hg(II) and I⁻.

    Science.gov (United States)

    He, Jiangling; Zhang, Haoran; Zou, Jinliang; Liu, Yingliang; Zhuang, Jianle; Xiao, Yong; Lei, Bingfu

    2016-05-15

    Herein, we report a simple, one-step reflux method for synthesis of photoluminescent carbon dots (CDs) using citric acid as the carbon source and diethylenetriamine (DETA) as the surface passivation reagent along with a high quantum yield (82.40%), the fluorescence intensity of the CDs was found to be effectively quenched by Hg(II) ions. Upon addition of I(-) to the CDs/Hg(II) complex dispersion, the fluorescence intensity of the CDs was significantly recovered. Furthermore, we developed an "off-on" fluorescence assay for the detection of I(-) using CDs/Hg(II) as a fluorescence probe. This probe enables the selective detection of Hg(II) with a linear range of 0-80 μM and a limit of detection is 0.201 µM and a limit of detection about I(-) is 0.234 µM with a linear range of 0-70 μM. Most importantly, the sensors can be successfully applied to the determination of Hg(II) and I(-) in real lake water and urine of cattles, the "off-on" sensor demonstrates high selectivity, repeatability, stability, which offer this CDs-based "off-on" fluorescent sensor a promising platform for environmental and biological sensing applications. PMID:26748370

  10. Detection of influenza A virus based on fluorescence resonance energy transfer from quantum dots to carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Tian Junping [Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Zhao Huimin, E-mail: zhaohuim@dlut.edu.cn [Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Liu Meng; Chen Yaqiong; Quan Xie [Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China)

    2012-04-20

    Highlights: Black-Right-Pointing-Pointer The quantum dots-ssDNA probe was designed for the determination of virus DNA. Black-Right-Pointing-Pointer The fluorescence of quantum dots was effectively quenched by carbon nanotubes. Black-Right-Pointing-Pointer The addition of target H5N1 DNA restored the quenched fluorescence of quantum dots. Black-Right-Pointing-Pointer The proposed method exhibited high sensitivity and good selectivity for H5N1 DNA. - Abstract: In this paper, a simple and sensitive approach for H5N1 DNA detection was described based on the fluorescence resonance energy transfer (FRET) from quantum dots (QDs) to carbon nanotubes (CNTs) in a QDs-ssDNA/oxCNTs system, in which the QDs (CdTe) modified with ssDNA were used as donors. In the initial stage, with the strong interaction between ssDNA and oxCNTs, QDs fluorescence was effectively quenched. Upon the recognition of the target, the effective competitive bindings of it to QDs-ssDNA occurred, which decreased the interactions between the QDs-ssDNA and oxCNTs, leading to the recovery of the QDs fluorescence. The recovered fluorescence of QDs was linearly proportional to the concentration of the target in the range of 0.01-20 {mu}M with a detection limit of 9.39 nM. Moreover, even a single-base mismatched target with the same concentration of target DNA can only recover a limited low fluorescence of QDs, illustrating the good anti-interference performance of this QDs-ssDNA/oxCNTs system. This FRET platform in the QDs-ssDNA/oxCNTs system was facilitated to the simple, sensitive and quantitative detection of virus nucleic acids and could have a wide range of applications in molecular diagnosis.

  11. High fluorescence S, N co-doped carbon dots as an ultra-sensitive fluorescent probe for the determination of uric acid.

    Science.gov (United States)

    Wang, Haiyan; Lu, Qiujun; Hou, Yuxin; Liu, Yalan; Zhang, Youyu

    2016-08-01

    Sulfur, nitrogen co-doped carbon dots (S, N co-doped C-dots) as highly selective fluorescent probe for uric acid (UA) detection were designed. The S, N co-doped C-dots with high quantum yield of 73.1% were prepared by hydrothermal method. It was found that the fluorescence of S, N co-doped C-dots was quenched apparently by hydroxyl radicals from Fenton reaction between H2O2 and Fe(2+). The production of H2O2 originated from the oxidization of UA by uricase. Therefore, an optical biosensor was developed for the detection of UA based on Fenton reaction and enzymatic reaction. Under the optimized conditions, two linear relationships between the ratio of fluorescence quenching of the C-dots and UA concentration were found in the range of 0.08-10µM and 10-50µM, respectively. The detection limit was down to 0.07µM. Moreover, the proposed biosensor was successfully applied to the detection of uric acid in human serum samples. PMID:27216657

  12. Predicting trace organic compound breakthrough in granular activated carbon using fluorescence and UV absorbance as surrogates.

    Science.gov (United States)

    Anumol, Tarun; Sgroi, Massimiliano; Park, Minkyu; Roccaro, Paolo; Snyder, Shane A

    2015-06-01

    This study investigated the applicability of bulk organic parameters like dissolved organic carbon (DOC), UV absorbance at 254 nm (UV254), and total fluorescence (TF) to act as surrogates in predicting trace organic compound (TOrC) removal by granular activated carbon in water reuse applications. Using rapid small-scale column testing, empirical linear correlations for thirteen TOrCs were determined with DOC, UV254, and TF in four wastewater effluents. Linear correlations (R(2) > 0.7) were obtained for eight TOrCs in each water quality in the UV254 model, while ten TOrCs had R(2) > 0.7 in the TF model. Conversely, DOC was shown to be a poor surrogate for TOrC breakthrough prediction. When the data from all four water qualities was combined, good linear correlations were still obtained with TF having higher R(2) than UV254 especially for TOrCs with log Dow>1. Excellent linear relationship (R(2) > 0.9) between log Dow and the removal of TOrC at 0% surrogate removal (y-intercept) were obtained for the five neutral TOrCs tested in this study. Positively charged TOrCs had enhanced removals due to electrostatic interactions with negatively charged GAC that caused them to deviate from removals that would be expected with their log Dow. Application of the empirical linear correlation models to full-scale samples provided good results for six of seven TOrCs (except meprobamate) tested when comparing predicted TOrC removal by UV254 and TF with actual removals for GAC in all the five samples tested. Surrogate predictions using UV254 and TF provide valuable tools for rapid or on-line monitoring of GAC performance and can result in cost savings by extended GAC run times as compared to using DOC breakthrough to trigger regeneration or replacement. PMID:25792436

  13. Phytotoxicity, Uptake, and Translocation of Fluorescent Carbon Dots in Mung Bean Plants.

    Science.gov (United States)

    Li, Wei; Zheng, Yinjian; Zhang, Haoran; Liu, Zulang; Su, Wei; Chen, Shi; Liu, Yingliang; Zhuang, Jianle; Lei, Bingfu

    2016-08-10

    Fluorescent carbon dots (CDs) have been widely studied in bioscience and bioimaging, but the effect of CDs on plants has been rarely studied. Herein, mung bean was adopted as a model plant to study the phytotoxicity, uptake, and translocation of red emissive CDs in plants. The incubation with CDs at a concentration range from 0.1 to 1.0 mg/mL induced physiological response of mung bean plant and imposed no phytotoxicity on mung bean growth. The lengths of the root and stem presented an increasing trend up to the treatment of 0.4 mg/mL. Confocal imaging showed that CDs were transferred from the roots to the stems and leaves by the vascular system through the apoplastic pathway. The uptake kinetics study was performed and demonstrated that the CDs were abundantly incubated by mung beans during both germination and growth periods. Furthermore, in vivo visualization of CDs provides potential for their successful application as delivery vehicles in plants based on the unique optical properties. PMID:27425200

  14. Estimation of Biochemical Oxygen Demand Based on Dissolved Organic Carbon, UV Absorption, and Fluorescence Measurements

    Directory of Open Access Journals (Sweden)

    Jihyun Kwak

    2013-01-01

    Full Text Available Determination of 5-d biochemical oxygen demand (BOD5 is the most commonly practiced test to assess the water quality of surface waters and the waste loading. However, BOD5 is not a good parameter for the control of water or wastewater treatment processes because of its long test period. It is very difficult to produce consistent and reliable BOD5 results without using careful laboratory quality control practices. This study was performed to develop software sensors to predict the BOD5 of river water and wastewater. The software sensors were based on the multiple regression analysis using the dissolved organic carbon (DOC concentration, UV light absorbance at 254 nm, and synchronous fluorescence spectra. River water samples and wastewater treatment plant (WWTP effluents were collected at 1-hour interval to evaluate the feasibility of the software sensors. In short, the software sensors developed in this study could well predict the BOD5 of river water (r=0.78 and for the WWTP effluent (r=0.90.

  15. Synthesis-modification integration: one-step fabrication of boronic acid functionalized carbon dots for fluorescent blood sugar sensing.

    Science.gov (United States)

    Shen, Pengfei; Xia, Yunsheng

    2014-06-01

    In this paper, we have presented a novel strategy to fabricate fluorescent boronic acid modified carbon dots (C-dots) for nonenzymatic blood glucose sensing applications. The functionalized C-dots are obtained by one-step hydrothermal carbonization, using phenylboronic acid as the sole precursor. Compared with conventional two-step fabrication of nanoparticle-based sensors, the present "synthesis-modification integration" strategy is simpler and more efficient. The added glucose selectively leads to the assembly and fluorescence quenching of the C-dots. Such fluorescence responses can be used for well quantifying glucose in the range of 9-900 μM, which is 10-250 times more sensitive than that of previous boronic acid based fluorescent nanosensing systems. Due to "inert" surface, the C-dots can well resist the interferences from various biomolecules and exhibit excellent selectivity. The proposed sensing system has been successfully used for the assay of glucose in human serum. Due to simplicity and effectivity, it exhibits great promise as a practical platform for blood glucose sensing. PMID:24694081

  16. Quenching of fluorene fluorescence by single-walled carbon nanotube dispersions with surfactants: application for fluorene quantification in wastewater.

    Science.gov (United States)

    Palencia, Sergio; Vera, Soledad; Díez-Pascual, Ana María; San Andrés, María Paz

    2015-06-01

    The fluorescence of fluorene in aqueous solutions of surfactants of different natures, anionic sodium dodecylsulphate (SDS), cationic cetyltrimethyl ammonium chloride (CTAC) and non-ionic polyoxyethylene-23-lauryl ether (Brij 35), as well as in single-walled carbon nanotube (SWCNT) dispersions in these surfactants, has been studied and compared. A fluorescence quenching phenomenon has been observed in the presence of SWCNT, the effect being stronger for dispersions in CTAC, related to the improved dispersion capability of this surfactant as revealed by microscopic observations and its stronger adsorption onto the SWCNT surfaces as inferred from the Raman spectra. SWCNT interact with fluorene causing a fluorescence quenching. The fluorescence intensity ratio, calculated in the absence and in the presence of SWCNT, follows the Stern-Volmer equation. For the CTAC concentration that provides the highest quenching effect, the analytical characteristics of the fluorimetric method like sensitivity, detection and quantification limits, repeatability, reproducibility and robustness have been calculated. Results demonstrate that it is possible to determine fluorene in a fortified wastewater sample in aqueous solutions of CTAC and SWCNT/CTAC dispersions, showing recoveries close to 100 %. The quenching effect found in this work could be useful for the development of an optical device that uses SWCNT-based receptors for fluorene detection and quantification in aqueous surfactant solutions. Graphical abstract Distribution of fluorene between single-walled carbon nanotubes and micelles. PMID:25893803

  17. Single Molecule Detection of H2O2 Mediating Angiogenic Redox Signaling on Fluorescent Single-Walled Carbon Nanotube Array

    OpenAIRE

    Kim, Jong-Ho; Arkalgud, Jyoti R.; Boghossian, Ardemis A; Zhang, Jingqing; Han, Jae-Hee; Reuel, Nigel F.; Ahn, Jin-Ho; Mukhopadhyay, Debabrata; Strano, Michael S.

    2011-01-01

    Reactive oxygen species, specifically hydrogen peroxide (H2O2), activate signal transduction pathways during angiogenesis, and therefore play an important role in physiological development as well as various pathophysiologies. Herein, we utilize a near infrared fluorescent single-walled carbon nanotube (SWNT) sensor array to measure the single molecule efflux of H2O2 from human umbilical vein endothelial cells (HUVEC) in response to angiogenic stimulation. Two angiogenic agents were investiga...

  18. Controllable synthesis of green and blue fluorescent carbon nanodots for pH and Cu(2+) sensing in living cells.

    Science.gov (United States)

    Shi, Lihong; Li, Yanyan; Li, Xiaofeng; Zhao, Bo; Wen, Xiangping; Zhang, Guomei; Dong, Chuan; Shuang, Shaomin

    2016-03-15

    We report a controllable strategy for fabrication of green and blue fluorescent carbon nanodots (CDs), and demonstrate their applications for pH and Cu(2+) sensing in living cells. Green and blue fluorescent CDs have been synthesized by hydrothermal method and pyrolysis of leeks, respectively, providing an easy way for the production of CDs without the request of tedious synthetic methodology or the use of toxic/expensive solvents and starting materials. Green fluorescent CDs (G-CDs) exhibit high tolerance to pH values and external cations. Blue fluorescent CDs (B-CDs) can be applied to pH and Cu(2+) sensing. The linear range of Cu(2+) detection is 0.01-10.00 μM and the detection limit is 0.05 μM. For pH detection, there is a good linearity in the pH range of 3.5-10.0. The linear and rapid response of B-CDs to Cu(2+) and pH is valuable for Cu(2+) and pH sensing in living cells. Confocal fluorescent imaging of human cervical carcinoma cells indicates that B-CDs could visualize Cu(2+) and pH fluctuations in living cells with negligible autofluorescence. PMID:26485174

  19. Synthesis and properties of SiNx coatings as stable fluorescent markers on vertically aligned carbon nanofibers

    Directory of Open Access Journals (Sweden)

    Ryan Pearce

    2014-04-01

    Full Text Available The growth of vertically aligned carbon nanofibers (VACNFs in a catalytic dc ammonia/acetylene plasma process on silicon substrates is often accompanied by sidewall deposition of material that contains predominantly Si and N. In fluorescent microscopy experiments, whereby VACNFs are interfaced to cell and tissue cultures for a variety of applications, it was observed that this material is broadly fluorescent. In this paper, we provide insight into nature of these silicon/nitrogen in-situ coatings. We propose a potential mechanism for deposition of SiNx coating on the sidewalls of VACNFs during PECVD synthesis and explore the origin of the coating's fluorescence. It is most likely that the substrate reacts with process gases similar to reactive sputtering and chemical vapor deposition (CVD, forming silane and other silicon bearing compounds prior to isotropic deposition as a SiNx coating onto the VACNFs. The formation of Sinanoclusters (NCs is also implicated due to a combination of strong fluorescence and elemental analysis of the samples. These broadly luminescent fibers can prove useful as registry markers in fluorescent cellular studies and for tagging and tracing applications.

  20. Evaluation of a Carbonic Anhydrase IX-Targeted Near-Infrared Dye for Fluorescence-Guided Surgery of Hypoxic Tumors.

    Science.gov (United States)

    Lv, Peng-Cheng; Roy, Jyoti; Putt, Karson S; Low, Philip S

    2016-05-01

    Proof-of-principle studies in ovarian, lung, and brain cancer patients have shown that fluorescence-guided surgery can enable removal of otherwise undetectable malignant lesions, decrease the number of cancer-positive margins, and permit identification of disease-containing lymph nodes that would have normally evaded resection. Unfortunately, the current arsenal of tumor-targeted fluorescent dyes does not permit identification of all cancers, raising the need to design new tumor-specific fluorescent dyes to illuminate the currently undetectable cancers. In an effort to design a more universal fluorescent cancer imaging agent, we have undertaken to synthesize a fluorophore that could label all hypoxic regions of tumors. We report here the synthesis, in vitro binding, and in vivo imaging of a near-infrared (NIR) fluorescent dye that is targeted to carbonic anhydrase IX (CA IX), i.e., a widely accepted marker of hypoxic tissues. The low molecular weight NIR probe, named Hypoxyfluor, is shown to bind CA IX with high affinity and accumulate rapidly and selectively in CA IX positive tumors. Because nearly all human cancers contain hypoxic regions that express CA IX abundantly, this NIR probe should facilitate surgical resection of a wide variety of solid tumors. PMID:27043317

  1. Highly fluorescent carbon dots as nanoprobes for sensitive and selective determination of 4-nitrophenol in surface waters

    International Nuclear Information System (INIS)

    We report on the synthesis of carbon dots (C-dots) by thermal carbonization of a mixture of ethyleneglycol bis-(2-aminoethyl ether)-N,N,N’,N’-tetraacetic acid (EGTA) and tris(hydroxymethyl)aminomethane (Tris). The resulting C-dots were characterized by X-ray diffraction, proton and carbon nuclear magnetic resonance, FTIR and fluorescence spectroscopy, and high-resolution TEM. The data reveal that the C-dots are mainly capped with hydroxy and carbonyl groups and are highly fluorescent with an emission peak that shifts from 427 to 438 nm if the excitation wavelength is increased from 310 to 360–370 nm. Fluorescence is quenched by 4-nitrophenol (4-NP), and this effect was exploited to design a simple and rapid protocol for the determination of 4-NP. The detection limit is 28 nM and the linear range extends from 0.1 to 50 μM. The method was successfully applied to the determination of 4-NP in spiked river and sea waters. (author)

  2. Nitrogen-doped carbon nanoparticle modulated turn-on fluorescent probes for histidine detection and its imaging in living cells

    Science.gov (United States)

    Zhu, Xiaohua; Zhao, Tingbi; Nie, Zhou; Miao, Zhuang; Liu, Yang; Yao, Shouzhuo

    2016-01-01

    In this work, nitrogen-doped carbon nanoparticle (N-CNP) modulated turn-on fluorescent probes were developed for rapid and selective detection of histidine. The as synthesized N-CNPs exhibited high fluorescence quantum yield and excellent biocompatibility. The fluorescence of N-CNPs can be quenched selectively by Cu(ii) ions with high efficiency, and restored by the addition of histidine owing to the competitive binding of Cu(ii) ions and histidine that removes Cu(ii) ions from the surface of the N-CNPs. Under the optimal conditions, a linear relationship between the increased fluorescence intensity of N-CNP/Cu(ii) ion conjugates and the concentration of histidine was established in the range from 0.5 to 60 μM. The detection limit was as low as 150 nM (signal-to-noise ratio of 3). In addition, the as-prepared N-CNP/Cu(ii) ion nanoprobes showed excellent biocompatibility and were applied for a histidine imaging assay in living cells, which presented great potential in the bio-labeling assay and clinical diagnostic applications.In this work, nitrogen-doped carbon nanoparticle (N-CNP) modulated turn-on fluorescent probes were developed for rapid and selective detection of histidine. The as synthesized N-CNPs exhibited high fluorescence quantum yield and excellent biocompatibility. The fluorescence of N-CNPs can be quenched selectively by Cu(ii) ions with high efficiency, and restored by the addition of histidine owing to the competitive binding of Cu(ii) ions and histidine that removes Cu(ii) ions from the surface of the N-CNPs. Under the optimal conditions, a linear relationship between the increased fluorescence intensity of N-CNP/Cu(ii) ion conjugates and the concentration of histidine was established in the range from 0.5 to 60 μM. The detection limit was as low as 150 nM (signal-to-noise ratio of 3). In addition, the as-prepared N-CNP/Cu(ii) ion nanoprobes showed excellent biocompatibility and were applied for a histidine imaging assay in living cells, which

  3. Visualization of individual single-walled carbon nanotubes by fluorescent polymer wrapping.

    Science.gov (United States)

    Didenko, Vladimir V; Moore, Valerie C; Baskin, David S; Smalley, Richard E

    2005-08-01

    Manipulating optical properties of single-walled nanotubes (SWNTs) is necessary for the development of nanoscale optical devices and probes for biomedical research. In life sciences it will make possible the direct observation of SWNTs inside living cells using optical microscopes. In the nanotechnology field it will enable the development of nanosensors with fluorescent reporting. However, the direct fluorescent labeling of SWNTs is obstructed by their strong light quenching qualities. Besides, chemical functionalization of SWNTs needed for the covalent attachment of fluorescent dyes could change favorable properties of nanotubes. Here we report that optical properties of SWNTs can be manipulated without their covalent modification by wrapping them with fluorescently labeled polymer poly(vinylpyrrolidone) (PVP-1300). Fluorescent PVP-1300 forms a monomolecular approximately 2.5 nm thick layer coiling around individual SWNTs and nanotube bundles. PVP casing is fluorescent although it is only several nanometers thick. This makes individual SWNTs observable by a fluorescent microscope. The spare polymer strands left over after wrapping around the relatively shorter nanotubes form junctions between SWNTs tying them together into new configurations, primarily Y- and psi-type junctions. The ability to use a single fluorescent polymer strand to fasten nanotubes together can be useful in assembly of nanotube-made devices. In PVP-covered SWNTs multiple fluorophores are attached to each single nanotube making them unique composite fluorophores attractive as parts of biological fluorescent probes and in the development of the new materials in photonics and nanotechnology. PMID:16089489

  4. Visualization of Individual Single-Walled Carbon Nanotubes by Fluorescent Polymer Wrapping

    Science.gov (United States)

    Moore, Valerie C.; Baskin, David S.; Smalley, Richard E.

    2007-01-01

    Manipulating optical properties of single-walled nanotubes (SWNTs) is necessary for the development of nanoscale optical devices and probes for biomedical research. In life sciences it will make possible the direct observation of SWNTs inside living cells using optical microscopes. In the nanotechnology field it will enable the development of nanosensors with fluorescent reporting. However, the direct fluorescent labeling of SWNTs is obstructed by their strong light quenching qualities. Besides, chemical functionalization of SWNTs needed for the covalent attachment of fluorescent dyes could change favorable properties of nanotubes. Here we report that optical properties of SWNTs can be manipulated without their covalent modification by wrapping them with fluorescently labeled polymer poly(vinylpyrrolidone) (PVP-1300). Fluorescent PVP-1300 forms a monomolecular ~2.5 nm thick layer coiling around individual SWNTs and nanotube bundles. PVP casing is fluorescent although it is only several nanometers thick. This makes individual SWNTs observable by a fluorescent microscope. The spare polymer strands left over after wrapping around the relatively shorter nanotubes form junctions between SWNTs tying them together into new configurations, primarily Y- and Ψ-type junctions. The ability to use a single fluorescent polymer strand to fasten nanotubes together can be useful in assembly of nanotube-made devices. In PVP-covered SWNTs multiple fluorophores are attached to each single nanotube making them unique composite fluorophores attractive as parts of biological fluorescent probes and in the development of the new materials in photonics and nanotechnology. PMID:16089489

  5. Pentosan-derived water-soluble carbon nano dots with substantial fluorescence: Properties and application as a photosensitizer

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qiong; Li, Wei; Wu, Yanjiao; Huang, Zhanhua; Liu, Shouxin, E-mail: liushouxin@126.com

    2014-10-01

    Graphical abstract: Water-soluble carbon nano dots (CNDs) with high fluorescence are synthesized from liquid by-products of hydrothermal carbonization of pentosan, the by-products of pulp refining. CNDs can be effectively used as photo sensitizer in the CNDs/TiO{sub 2} system for methyl blue (MB) degradation under visible light irradiation, spectral response range of CNDs/TiO{sub 2} system can be widen from only UV region to part visible-light region (400–550 nm). - Highlights: • Water-soluble CNDs with abundant oxygen-containing groups can be obtained from the liquid by-products of hydrothermal carbonization of pentosan. • CNDs show excellent photoluminescence, pH sensitivity as well high stability. • CNDs/TiO{sub 2} system can be used as visible-light catalysts for the degradation of MB effectively. - Abstract: The hydrothermal carbonization of monosaccharides and polysaccharides is widely used in the production of carbonaceous material with a desired structure. However, the liquid products are regarded as waste and discarded. Here, we report a facile approach for the synthesis of water-soluble carbon nano dots (CNDs) with substantial fluorescence from the liquid by-products of the hydrothermal carbonization of pentosan, thus the by-products of pulp refining. The synthesized CNDs are monodispersed spheres with abundant oxygen-containing groups and they have an average size of 30 nm. Quantum yield measurements revealed CNDs with substantial green photoluminescence (PL) without passivation. Additionally, excitation was independent, pH-sensitive and stable. The use of CNDs as a photosensitizer in the CNDs/TiO{sub 2} system for methylene blue (MB) degradation under visible light irradiation is attractive. The spectral response range of the CNDs/TiO{sub 2} system can be widened from the UV region to a part of the visible light region (400–550 nm)

  6. Encodable multiple-fluorescence CdTe@carbon nanoparticles from nanocrystal/colloidal crystal guest-host ensembles

    Science.gov (United States)

    Guo, Xin; Wang, Cai-Feng; Mao, Li-Hua; Zhang, Jing; Yu, Zi-Yi; Chen, Su

    2013-04-01

    We report herein the controllable generation of encodable multi-fluorescence CdTe@carbon nanoparticles (CdTe@C NPs) via the pyrolysis of quantum dot/photonic crystal (QD/PC) guest-host ensembles. The precursors of CdTe/poly(styrene-co-glycidylmethacrylate) (PS-co-PGMA) QD/PC guest-host ensembles were initially formed via the assembly of epoxy groups of PCs and carboxyl groups on the surface of CdTe QDs, followed by a pyrolysis process to generate CdTe@C NPs. The as-prepared CdTe@C NPs not only integrate the optical properties for both the carbon and CdTe QD constituents, but also enable an impressive enhancement of the fluorescence lifetime for CdTe QDs. The multifarious fluorescent spectra coding for CdTe@C NPs was further generated through regulating the embedded sizes or concentrations of CdTe QDs and the excitation wavelength, and their applications in DNA detection and luminescent patterns were achieved.

  7. Tunable Carbon-Dot-Based Dual-Emission Fluorescent Nanohybrids for Ratiometric Optical Thermometry in Living Cells.

    Science.gov (United States)

    Wang, Chuanxi; Lin, Huihui; Xu, Zhenzhu; Huang, Yijun; Humphrey, Mark G; Zhang, Chi

    2016-03-01

    The use of carbon-dot-based dual-emission fluorescent nanohybrids (DEFNs) as versatile nanothermometry devices for spatially resolved temperature measurements in living cells is demonstrated. The carbon dots (CDs) are prepared in the organic phase and display tunable photoluminescence (PL) across a wide visible range by adjusting the excitation wavelengths and extend of N-doping. DEFNs are formed in a straightforward fashion from CDs (emitting blue PL) and gold nanoclusters (AuNCs, emitting red PL). The DEFNs display ideal single-excitation, dual-emission with two well-resolved, intensity-comparable fluorescence peaks, and function in optical thermometry with high reliability and accuracy by exploiting the temperature sensitivity of their fluorescence intensity ratio (blue/red). Furthermore, the DEFNs have been introduced into cells, exhibiting good biocompatibility, and have facilitated physiological temperature measurements in the range of 25-45 °C; the DEFNs can therefore function as "non-contact" tools for the accurate measurement of temperature and its gradient inside a living cell. PMID:26909643

  8. Burkina Faso - BRIGHT II

    Data.gov (United States)

    Millenium Challenge Corporation — Millennium Challenge Corporation hired Mathematica Policy Research to conduct an independent evaluation of the BRIGHT II program. The three main research questions...

  9. Monitoring the activity and inhibition of alkaline phosphatase via quenching and restoration of the fluorescence of carbon dots

    International Nuclear Information System (INIS)

    We report that the fluorescence of carbon dots (C-dots) in water is quenched by the addition of Cu2+ ions, and that the subsequent addition of pyrophosphate (PPi) restores fluorescence. This is likely to be due to the coordination of Cu2+ by PPi. This effect forms the basis for a method to determine the activity and inhibition of the enzyme alkaline phosphatase (ALP). If ALP is added to a system composed of C-dots, Cu2+ and PPi, fluorescence will decrease over time because ALP catalyzes the hydrolysis of PPi to form orthophosphate (Pi). This results in a release of the quencher Cu2+. The decrease in fluorescence is related to the activity of ALP. The method is simple and displays good sensitivity (with a limit of detection of 1 units per L) and selectivity. The method was successfully applied to the determination of ALP in serum samples. We also have studied the inhibitory effect of Pi on the activity of ALP. We presume that this method holds a large potential in terms of diagnosis of ALP-related diseases, to evaluate the function of ALP in biological systems and in screening for potential inhibitors of ALP. (author)

  10. Fluorescence aggregation assay for the protein biomarker mucin 1 using carbon dot-labeled antibodies and aptamers

    International Nuclear Information System (INIS)

    We have developed a sensitive fluorescence assay for the protein biomarker mucin 1 (MUC1). It is based on the aggregation of functionalized carbon dots (CDs) in the presence of MUC1. The CDs with a size of ∼2 nm display strong blue-green intrinsic fluorescence. Antibodies against MUC1 and the MUC1 aptamer were covalently conjugated to the CDs, and the immunoreaction between CD-labeled antibody to MUC1, and of the CD-labeled aptamer to MUC1 resulted in the formation of a sandwich structure that is accompanied by aggregation of CDs and quenching of fluorescence. The change in fluorescence is linearly related to the MUC1 concentration in the 5 to 100 nM range, with a detection limit at 2 nM. The assay was applied to the determination of MUC1 in (spiked) real serum samples, and good recoveries (ranging from 94.2 to 98.1 %) were obtained. This assay is cost-effective and convenient. It has a wide scope in that it, conceivably, can be extended to assays for other proteins and biomarkers of clinical interest. (author)

  11. Investigating the usefulness of satellite derived fluorescence data in inferring gross primary productivity within the carbon cycle data assimilation system

    Directory of Open Access Journals (Sweden)

    E. N. Koffi

    2015-01-01

    Full Text Available We investigate the utility of satellite measurements of chlorophyll fluorescence (Fs in constraining gross primary productivity (GPP. We ingest Fs measurements into the Carbon-Cycle Data Assimilation System (CCDAS which has been augmented by the fluorescence component of the Soil Canopy Observation, Photochemistry and Energy fluxes (SCOPE model. CCDAS simulates well the patterns of Fs suggesting the combined model is capable of ingesting these measurements. However simulated Fs is insensitive to the key parameter controlling GPP, the carboxylation capacity (Vcmax. Simulated Fs is sensitive to both the incoming absorbed photosynthetically active radiation (aPAR and leaf chlorophyll concentration both of which are treated as perfectly known in previous CCDAS versions. Proper use of Fs measurements therefore requires enhancement of CCDAS to include and expose these variables.

  12. One-pot electrochemical synthesis of functionalized fluorescent carbon dots and their selective sensing for mercury ion

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Yuxin; Lu, Qiujun; Deng, Jianhui; Li, Haitao; Zhang, Youyu, E-mail: zhangyy@hunnu.edu.cn

    2015-03-25

    Highlights: • One-pot electrochemical synthesis of functionalized carbon dots (C-Dots). • The C-Dots can serve as a fluorescent probe for sensitive detection of Hg{sup 2+}. • The detection limit for Hg{sup 2+} is 3.3 nM. • The sensor is successfully applied to Hg{sup 2+} determination in real samples. - Abstract: We propose a simple, economical, and one-pot method to synthesize water-soluble functionalized fluorescent carbon dots (C-Dots) through electrochemical carbonization of sodium citrate and urea. The as-prepared C-Dots have good photostability and exhibit a high quantum yield of 11.9%. The sizes of the C-Dots are mainly distributed in the range of 1.0–3.5 nm with an average size of 2.4 nm. It has been further used as a novel label-free sensing probe for selective detection of Hg{sup 2+} ions with detection limit as low as 3.3 nM. The detection linear range is 0.01–10 μM. The as-prepared C-Dots are also successfully applied for the determination of Hg{sup 2+} in real water samples.

  13. Linking solar induced fluorescence and the photochemical reflectance index to carbon assimilation in a cornfield

    Science.gov (United States)

    Cheng, Y.; Middleton, E.; Zhang, Q.; Corp, L.; Campbell, P. K.; Huemmrich, K. F.; Kustas, W.; Daughtry, C. S.; Dulaney, W. P.; Russ, A.

    2012-12-01

    Determining the health and vigor of vegetation using high spectral resolution remote sensing techniques is a critical component in monitoring productivity from both natural and managed ecosystems and their feedbacks to climate. This presentation summarizes a field campaign conducted in a USDA-ARS experimental cornfield site located in Beltsville, MD, USA over a five-year period. The site is equipped with an instrumented tower which makes continuous eddy covariance measurements of CO2 along with incoming PAR. Hyperspectral reflectance observations were acquired over corn canopies with a USB4000 Miniature Fiber Optic Spectrometer (Ocean Optics Inc., Dunedin, Florida, USA) at multiple times a day at various stages through the growing season. On all field days, supporting plant information and leaf level data were acquired (e.g., CO2 gas exchange) as well as biophysical field data, including leaf area index (LAI), mid-day canopy PAR transmission, soil reflectivity, and soil moisture. The canopy optical measurements enabled retrievals of the photochemical reflectance index (PRI) and solar induced fluorescence (SIF) centered at O2-A and -B bands. These two spectrally based bio-indicators have been widely utilized in studies to assess whether vegetation is performing near-optimally or exhibiting symptoms of environmental stress (e.g., drought or nutrient deficiency, non-optimal temperatures, etc.). Both SIF and PRI expressed diurnal dynamics and seasonal changes that followed environmental conditions and physiological status of the cornfield. We further investigated the correlation between these two retrievals and the flux tower based carbon assimilation observations (i.e. gross ecosystem production, GEP). We were able to successfully model the variation of GEP (r2=0.81; RMSE=0.18 mg CO2/m2/s) by utilizing both SIF and PRI. Several cross-validation algorithms were applied to the model to demonstrate the robustness and consistency of the model. Our results suggest great

  14. Sensitive detection of biothiols and histidine based on the recovered fluorescence of the carbon quantum dots–Hg(II) system

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Juan; Zhang, Fengshuang; Yan, Xu; Wang, Long; Yan, Jin [College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Ding, Hong [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China); Ding, Lan, E-mail: dinglan@jlu.edu.cn [College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012 (China)

    2015-02-15

    Highlights: • Carbon quantum dots-based probe was used for detection of GSH, Cys or His. • The fluorescence of CQDs was quenched by Hg(II) and then recovered by GSH, Cys or His. • No further surface modification or purification of CQDs was required. • This sensor exhibits superior accuracy and sensitivity. • The proposed method was simple in design, fast in operation. - Abstract: In this paper, we presented a novel, rapid and highly sensitive sensor for glutathione (GSH), cysteine (Cys) and histidine (His) based on the recovered fluorescence of the carbon quantum dots (CQDs)–Hg(II) system. The CQDs were synthesized by microwave-assisted approach in one pot according to our previous report. The fluorescence of CQDs could be quenched in the presence of Hg(II) due to the coordination occurring between Hg(II) and functional groups on the surface of CQDs. Subsequently, the fluorescence of the CQDs–Hg(II) system was recovered gradually with the addition of GSH, Cys or His due to their stronger affinity with Hg(II). A good linear relationship was obtained from 0.10 to 20 μmol L{sup −1} for GSH, from 0.20 to 45 μmol L{sup −1} for Cys and from 0.50 to 60 μmol L{sup −1} for His, respectively. This method has been successfully applied to the trace detection of GSH, Cys or His in human serum samples with satisfactory results. The proposed method was simple in design and fast in operation, which demonstrated great potential in bio-sensing fields.

  15. Analysis of laser-induced-fluorescence carbon monoxide measurements in turbulent nonpremixed flames.

    Science.gov (United States)

    Mokhov, A V; Levinsky, H B; van der Meij, C E; Jacobs, R A

    1995-10-20

    The influence of fluctuating concentrations and temperature on the laser-induced-fluorescence (LIF) measurement of CO in turbulent flames is described, under conditions in which the fluorescence and the temperature are measured independently. The analysis shows that correlations between CO concentration and temperature can bias the averaged mole fraction extracted from LIF measurements. The magnitude of the bias can exceed the order of the average CO mole fraction. Further, LIF measurements of CO concentrations in a turbulent, nonpremixed, natural gas flame are described. The averaged CO mole fractions are derived from the fluorescence measurements by the use of flame temperatures independently measured by coherent anti-Stokes Raman spectroscopy. Analysis of the fluctuations in measured temperature and fluorescence indicates that temperature and CO concentrations in flame regions with intensive mixing are indeed correlated. In the flame regions where burnout of CO has ceased, the LIF measurements of the CO mole fraction correspond to the probe measurements in exhaust. PMID:21060569

  16. BrightFocus Foundation

    Science.gov (United States)

    ... size: A A Contrast En Español Donate BrightFocus Foundation Alzheimer’s Disease Research Macular Degeneration Research National Glaucoma ... Bovenkamp, Ph.D., Scientific Program Officer for BrightFocus Foundation, about the basic science and therapeutic research the ...

  17. Visualization of Individual Single-Walled Carbon Nanotubes by Fluorescent Polymer Wrapping

    OpenAIRE

    Didenko, Vladimir V.; Moore, Valerie C.; Baskin, David S.; Smalley, Richard E.

    2005-01-01

    Manipulating optical properties of single-walled nanotubes (SWNTs) is necessary for the development of nanoscale optical devices and probes for biomedical research. In life sciences it will make possible the direct observation of SWNTs inside living cells using optical microscopes. In the nanotechnology field it will enable the development of nanosensors with fluorescent reporting. However, the direct fluorescent labeling of SWNTs is obstructed by their strong light quenching qualities. Besid...

  18. The Seasonal Cycle of Satellite Chlorophyll Fluorescence Observations and its Relationship to Vegetation Phenology and Ecosystem Atmosphere Carbon Exchange

    Science.gov (United States)

    Joiner, J.; Yoshida, Y.; Vasilkov, A. P.; Schaefer, K.; Jung, M.; Guanter, L.; Zhang, Y; Garrity, S.; Middleton, E. M.; Huemmrich, K. F.; Gu, L.; Marchesini, L. Belelli

    2014-01-01

    Mapping of terrestrial chlorophyll uorescence from space has shown potentialfor providing global measurements related to gross primary productivity(GPP). In particular, space-based fluorescence may provide information onthe length of the carbon uptake period that can be of use for global carboncycle modeling. Here, we examine the seasonal cycle of photosynthesis asestimated from satellite fluorescence retrievals at wavelengths surroundingthe 740nm emission feature. These retrievals are from the Global OzoneMonitoring Experiment 2 (GOME-2) flying on the MetOp A satellite. Wecompare the fluorescence seasonal cycle with that of GPP as estimated froma diverse set of North American tower gas exchange measurements. Because the GOME-2 has a large ground footprint (40 x 80km2) as compared with that of the flux towers and requires averaging to reduce random errors, we additionally compare with seasonal cycles of upscaled GPP in the satellite averaging area surrounding the tower locations estimated from the Max Planck Institute for Biogeochemistry (MPI-BGC) machine learning algorithm. We also examine the seasonality of absorbed photosynthetically-active radiation(APAR) derived with reflectances from the MODerate-resolution Imaging Spectroradiometer (MODIS). Finally, we examine seasonal cycles of GPP as produced from an ensemble of vegetation models. Several of the data-driven models rely on satellite reflectance-based vegetation parameters to derive estimates of APAR that are used to compute GPP. For forested sites(particularly deciduous broadleaf and mixed forests), the GOME-2 fluorescence captures the spring onset and autumn shutoff of photosynthesis as delineated by the tower-based GPP estimates. In contrast, the reflectance-based indicators and many of the models tend to overestimate the length of the photosynthetically-active period for these and other biomes as has been noted previously in the literature. Satellite fluorescence measurements therefore show potential for

  19. Nitrogen-doped carbon dots originating from unripe peach for fluorescent bioimaging and electrocatalytic oxygen reduction reaction.

    Science.gov (United States)

    Atchudan, Raji; Edison, Thomas Nesakumar Jebakumar Immanuel; Lee, Yong Rok

    2016-11-15

    This paper reports the robust hydrothermal synthesis of nitrogen doped carbon dots (N-CDs) using the unripe fruit of Prunus persica (peach) as the carbon precursor and aqueous ammonia as the nitrogen source. The optical properties of synthesized N-CDs were characterized by ultraviolet visible (UV-Vis) and fluorescence spectroscopy techniques. The synthesized N-CDs were emitted blue light when excitated with a portable UV lamp. The materials with the optical properties were characterized further by high resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD), Raman, Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS). The mean size of the N-CDs was approximately 8nm, as calculated from the HRTEM image. The d-spacing of N-CDs, calculated using Bragg law, was approximately 0.21nm, which was consistent with the interlayer distance calculated from the HRTEM image. FT-IR spectroscopy and XPS revealed the presence of the phytoconstituents functionalities of peach fruit over the N-CDs surface and a high level of nitrogen doping on carbon dots (CDs) was confirmed by XPS studies. These results suggest that the unripe fruit extract of peach is an ideal candidate for the preparation of N-CDs. The resulting N-CDs showed excellent optical properties in water. The synthesized N-CDs exhibited a high fluorescence quantum yield and low cytotoxicity, and can be used as fluorescence imaging probes. In addition, the N-CDs were catalytically activite towards the oxygen reduction reaction (ORR). The N-CDs exhibited good catalytic activity in an alkaline medium (0.1M KOH) with a remarkable ORR of approximately 0.72V vs reversible hydrogen electrode (RHE), and O2 reduction follows mainly a 2 electron pathway by being reduced to hydrogen peroxide. The 2-electron reduction pathway is used in industry for H2O2 production. PMID:27479911

  20. Turn-off fluorescence sensor for the detection of ferric ion in water using green synthesized N-doped carbon dots and its bio-imaging.

    Science.gov (United States)

    Edison, Thomas Nesakumar Jebakumar Immanuel; Atchudan, Raji; Shim, Jae-Jin; Kalimuthu, Senthilkumar; Ahn, Byeong-Cheol; Lee, Yong Rok

    2016-05-01

    This paper reports turn-off fluorescence sensor for Fe(3+) ion in water using fluorescent N-doped carbon dots as a probe. A simple and efficient hydrothermal carbonization of Prunus avium fruit extract for the synthesis of fluorescent nitrogen-doped carbon dots (N-CDs) is described. This green approach proceeds quickly and provides good quality N-CDs. The mean size of synthesized N-CDs was approximately 7nm calculated from the high-resolution transmission electron microscopic images. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy revealed the presence of -OH, -NH2, -COOH, and -CO functional groups over the surface of CDs. The N-CDs showed excellent fluorescent properties, and emitted blue fluorescence at 411nm upon excitation at 310nm. The calculated quantum yield of the synthesized N-CDs is 13% against quinine sulfate as a reference fluorophore. The synthesized N-CDs were used as a fluorescent probe towards the selective and sensitive detection of biologically important Fe(3+) ions in water by fluorescence spectroscopy and for bio-imaging of MDA-MB-231 cells. The limit of detection (LOD) and the Stern-Volmer quenching constant for the synthesized N-CDs were 0.96μM and 2.0958×10(3)M of Fe(3+) ions. The green synthesized N-CDs are efficiently used as a promising candidate for the detection of Fe(3+) ions and bio-imaging. PMID:26994332

  1. Sunspot Bright Points

    CERN Document Server

    Choudhary, Debi Prasad

    2010-01-01

    We used the flux calibrated images through the Broad Band Filter Imager and Stokes Polarimeter data obtained with the Solar Optical Telescope onboard the Hinode spacecraft to study the properties of bright points in and around the sunspots. The well isolated bright points were selected and classified as umbral dot, peripheral umbral dot, penumbral grains and G-band bright point depending on their location. Most of the bright points are smaller than about 150 km. The larger points are mostly associated with the penumbral features. The bright points are not uniformly distributed over the umbra but preferentially located around the penumbral boundary and in the fast decaying parts of umbra. The color temperature of the bright points, derived using the continuum irradiance, are in the range of 4600 K to 6600 K with cooler ones located in the umbra. The temperature increases as a function of distance from the center to outside. The G-band, CN-band and CaII H flux of the bright points as a function of their blue ba...

  2. Hybrid carbon source for producing nitrogen-doped polymer nanodots: one-pot hydrothermal synthesis, fluorescence enhancement and highly selective detection of Fe(iii)

    Science.gov (United States)

    Lai, Tiantian; Zheng, Enhui; Chen, Lixian; Wang, Xuyang; Kong, Lichun; You, Chunping; Ruan, Yongming; Weng, Xuexiang

    2013-08-01

    Polymer nanodots (PNDs) from a hybrid carbon source (glucose and glycine) which exhibit a stronger fluorescence than the PNDs from a single source (glucose or glycine) are obtained by one-pot hydrothermal treatment. It is attractive that PNDs can be used as an effective fluorescent probe for the detection of iron ions with good selectivity and sensitivity in an aqueous solution.Polymer nanodots (PNDs) from a hybrid carbon source (glucose and glycine) which exhibit a stronger fluorescence than the PNDs from a single source (glucose or glycine) are obtained by one-pot hydrothermal treatment. It is attractive that PNDs can be used as an effective fluorescent probe for the detection of iron ions with good selectivity and sensitivity in an aqueous solution. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr02014b

  3. A simple turn on fluorescent sensor for the selective detection of thiamine using coconut water derived luminescent carbon dots.

    Science.gov (United States)

    Purbia, Rahul; Paria, Santanu

    2016-05-15

    In this study microwave-assisted hydrothermal method was used to prepare highly luminescent carbon dots (1-6 nm size) within a minute from tender coconut (Cocos nucifera) water. The synthesized carbon dots (C-dots) exhibit emission of blue and green lights while excited at 390 and 450 nm wavelengths, respectively. As an application, these C-dots were tested for a simple "turn on" fluorescent sensor for rapid detection of thiamine (vitamin B1). The detection of thiamine in human body is very important to prevent various diseases such as beriberi, neurological disorders, optic neuropathy, etc. The fluorescence emission intensity of C-dots quenches after addition of Cu(2+) ion and then again increases selectively (turn on) after the addition of thiamine. The fluorescence emission intensity enhancement of Cu(2+) ion modified C-dots in the presence of thiamine exhibits a linear relationship within the thiamine concentration range of 10-50 μM. The limit of detection was found to be 280 nM from this study. The selectivity of the detection was also tested in the presence of different organic molecules and inorganic ions (Ca(2+), Mg(2+), Na(+), K(+), Cl(-), SO4(2-), and NO3(-)) which are present in blood serum and urine and found to be almost no interference in the detection. Finally, to see the applicability in real samples a commercial vitamin capsule was tested and found less than 3% error in the detected concentration. The C-dots were also used for bioimaging of fungus and the results show they are also suitable for this application too. PMID:26745793

  4. Fluorescent retroreflective signing of work zones : abstract

    NARCIS (Netherlands)

    Vos, A.P. de; Horst, A.R.A. van der; Alferdinck, J.W.A.M.; Kooi, F.L.

    1999-01-01

    Fluorescent retroreflective materials increase the brightness of traffic signs. In construction work zones a benefit is expected from the increased conspicuity of fluorescent retroreflective signs. Fluorescent material can be used instead of non-fluorescent materials both for the advance warning sig

  5. Facile and Sensitive Fluorescence Sensing of Alkaline Phosphatase Activity with Photoluminescent Carbon Dots Based on Inner Filter Effect.

    Science.gov (United States)

    Li, Guoliang; Fu, Huili; Chen, Xuejie; Gong, Peiwei; Chen, Guang; Xia, Lian; Wang, Hua; You, Jinmao; Wu, Yongning

    2016-03-01

    A simple and sensitive fluorescent assay for detecting alkaline phosphatase (ALP) based on the inner filter effect (IFE) has been proven, which is conceptually different from the previously reported ALP fluorescent assays. In this sensing platform, N-doped carbon dots (CDs) with a high quantum yield of 49% were prepared by one-pot synthesis and were directly used as a fluorophore in IFE. p-Nitrophenylphosphate (PNPP) was employed to act as an ALP substrate, and its enzyme catalytic product (p-nitrophenol (PNP)) was capable of functioning as a powerful absorber in IFE to influence the excitation of fluorophore (CDs). When in the presence of ALP, PNPP was transformed into PNP and induced the absorption band transition from 310 to 405 nm, which resulted in the complementary overlap between the absorption of PNP and the excitation of CDs. Because of the competitive absorption, the excitation of CDs was significantly weakened, resulting in the quenching of CDs. The present IFE-based sensing strategy showed a good linear relationship from 0.01 to 25 U/L (R(2) = 0.996) and provided an exciting detection limit of 0.001 U/L (signal-to-noise ratio of 3). The proposed sensing approach was successfully applied to ALP sensing in serum samples, ALP inhibitor investigation and phosphatase cell imaging. The presented IFE-based CDs fluorescence sensing strategy gives new insight on the development of the facile and sensitive optical probe for enzyme activity assay because the surface modification or the linking between the receptor and the fluorophore is no longer required. PMID:26820049

  6. Boronic acid functionalized N-doped carbon quantum dots as fluorescent probe for selective and sensitive glucose determination

    Science.gov (United States)

    Jiang, Guohua; Jiang, Tengteng; Li, Xia; Wei, Zheng; Du, Xiangxiang; Wang, Xiaohong

    2014-04-01

    Nitrogen doped carbon quantum dots (NCQDs) of about 10 nm in diameter have been obtained by hydrothermal reaction from collagen. Because of the superiority of water dispersion, low toxicity and ease of functionlization, the NCQDs were designed as a glucose sensor after covalent grafting by 3-aminophenylboronic (APBA) (APBA-NCQDs). The as-prepared APBA-NCQDs were imparted with glucose sensitivity and selectivity from other saccharides via fluorescence (FL) quenching effect at physiological pH and at room temperature, which show high sensitivity and specificity for glucose determination with a wide range from 1 mM to 14 mM. FL quenching mechanism of APBA-NCQDs was also investigated by adding an external quencher. The APBA-NCQDs-based platform is an environmentally friendly way to substitute inorganic quantum dots containing heavy metals which offer a facile and low cost detection method.

  7. Fluorescent sulfonamide carbonic anhydrase inhibitors incorporating 1,2,3-triazole moieties: Kinetic and X-ray crystallographic studies.

    Science.gov (United States)

    Carta, Fabrizio; Ferraroni, Marta; Scozzafava, Andrea; Supuran, Claudiu T

    2016-01-15

    Fluorescent sulfonamide carbonic anhydrase (CA, EC 4.2.1.1) inhibitors (CAIs) were essential for demonstrating the role played by the tumor-associated isoform CA IX in acidification of tumors, cancer progression towards metastasis and for the development of imaging and therapeutic strategies for the management of hypoxic tumors which overexpress CA IX. However, the presently available such compounds are poorly water soluble which limits their use. Here we report new fluorescent sulfonamides 7, 8 and 10 with increased water solubility. The new derivatives showed poor hCA I inhibitory properties, but were effective inhibitors against the hCA II (KIs of 366-127 nM), CA IX (KIs of 8.1-36.9 nM), CA XII (KIs of 4.1-20.5 nM) and CA XIV (KIs of 12.8-53.6 nM). A high resolution X-ray crystal structure of one of these compounds bound to hCA II revealed the factors associated with the good inhibitory properties. Furthermore, this compound showed a three-fold increase of water solubility compared to a similar derivative devoid of the triazole moiety, making it an interesting candidate for ex vivo/in vivo studies. PMID:26682703

  8. Enhanced sorption of mercury from compact fluorescent bulbs and contaminated water streams using functionalized multiwalled carbon nanotubes

    International Nuclear Information System (INIS)

    Highlights: • Oxidized (CNT-OX), CNT-I, CNT-S were prepared. • Capacity of CNT-S (151.5 mg/g) was higher than other CNTs. • Applied to the removal of Hg(II) from spiked and natural coal wash waters. • Applied to the removal of Hg(0) from compact fluorescent lamps. - Abstract: Three different functionalized multiwalled carbon nanotubes were prepared, namely, oxidized CNTs (CNT-OX), iodide incorporated MWCNT (CNT-I) and sulfur incorporated MWCNT (CNT-S). The as prepared adsorbents were structurally characterized by various spectral techniques like scanning electron microscopy (SEM), energy dispersive X-ray (EDAX), Brunauer, Emmett, and Teller (BET) surface area analyzer, Fourier transform infra red (FTIR) and Raman spectroscopy. Loading of iodide and sulfur was evident from the EDAX graphs. The adsorption properties of Hg2+ as a function of pH, contact time and initial metal concentration were characterized by Cold vapor AAS. The adsorption kinetics fitted the Pseudo second order kinetics and equilibrium was reached within 90 min. The experimental data were modeled with Langmuir, Freundlich, Dubinin-Redushkevich and Temkin isotherms and various isotherm parameters were evaluated. It was found that the mercury adsorption capacity for the prepared adsorbents were in the order of CNT-S > CNT-I > CNT-OX > CNT. Studies have been conducted to demonstrate the applicability of the sorbent toward the removal of Hg(0) from broken compact fluorescent light (CFL) bulbs and Hg(II) from contaminated water streams

  9. Single-step preparation of fluorescent carbon nanoparticles, and their application as a fluorometric probe for quercetin

    International Nuclear Information System (INIS)

    We report on a method for the determination of quercetin based on the quenching of the fluorescence of carbon nanoparticles (CNPs). The CNPs were prepared by carefully adding an aqueous solution of glucose to solid diphosphorus pentoxide. This single-step method proceeds rapidly and gives large quantities of CNPs. Neither high temperatures nor complicated synthesis steps are needed. The resulting CNPs have an average size of 120 nm and were characterized by high-resolution TEM, FT-IR, elemental analysis and spectrofluorometry. The fluorescence of the CNPs decreases with increasing concentrations of the flavonoid quercetin, with a linear response to quercetin in the 3.3 to 41.2 μM concentration range in pH 6.0 water solution and also in a solution containing 16 % (v/v) of fetal bovine serum. The detection limit is as low as 0.175 μM, and the Stern-Volmer quenching constant is 4.34 × 104 M−1. (author)

  10. Insitu measurements of laser-induced-fluorescence spectra of single atmospheric organic carbon aerosol particles for their partial classification. (Invited)

    Science.gov (United States)

    Pinnick, R. G.; Pan, Y.; Hill, S.; Rosen, J. M.; Chang, R. K.

    2009-12-01

    Aerosols are ubiquitous in the earth’s atmosphere. Within the last two decades, the importance of organic carbon aerosols (OCAs) has been widely recognized. OCAs have both natural and anthropogenic sources and have effects ranging from atmospheric radiative forcing to human health. Improved methods for measuring and classifying OCAs are needed for better understanding their sources, transformation, and fate. In this talk we focus on the use of a relatively new technique for characterization of single OCA particles in atmospheric aerosol: ultraviolet laser-induced-fluorescence (UV-LIF). UV-LIF spectra of atmospheric aerosols measured at multiple sites with different regional climate (Adelphi, MD, New Haven, CT, and Las Cruces, NM) are reported. A hierarchical clustering method was used to cluster (approximately 90%) of the single-particle UV-LIF spectra into 8-10 groups (clusters). Some of these clusters have spectra that are similar to spectra of some important classes of atmospheric aerosol, such as humic/fulvic acids and humic-like substances, bacteria, cellulose, marine aerosol, and polycyclic aromatic hydrocarbons. The most highly populated clusters, and some of the less populated ones, appear at all sites. On average, spectra characteristic of humic/fulvic acids and humic-like-substances (HULIS) comprise 28-43% of fluorescent particles at all three sites; whereas cellulose-like spectra contribute only 1-3%.

  11. High Brightness Test Stand

    International Nuclear Information System (INIS)

    The High Brightness Test Stand is a 2 MeV, less than or equal to 10 kA electron accelerator module. This accelerator module, designed as an upgrade prototype for the Advanced Test Accelerator (ATA), combines solid state nonlinear magnetic drives with state-of-the-art induction linac technology. The facility serves a dual role, as it not only provides a test bed for this new technology, but is used to develop high brightness electron optics. We will both further describe the accelerator, as well as present some of the preliminary electron optics measurements

  12. A framework to quantify the determinants of canopy photosynthesis and carbon uptake using time series of chlorophyll fluorescence

    Science.gov (United States)

    Kellner, J. R.; Cushman, K. C.; Kendrick, J. A.; Silva, C. E.; Wiseman, S. M.; Yang, X.

    2015-12-01

    Uncertainty over the sign and magnitude of environmental forcing agents on fluxes of tropical forest carbon could be reduced with measurements of canopy photosynthesis. But no existing method can quantify photosynthesis within individual plants at scales larger than a few cm. Portable leaf chambers can determine leaf-level gas exchange, and eddy-covariance instruments infer the net ecosystem-atmosphere carbon flux. These endpoints represent an axis of granularity and extent. Single leaf measurements are finely grained, but necessarily limited in extent, and gas exchange for whole landscapes cannot resolve the performance or contributions of individual plants. This limits the ability of scientists to test mechanistic demographic and physiological hypotheses about the drivers of photosynthesis in ecosystems, and therefore to understand the determinants of carbon fluxes between tropical ecosystems and the atmosphere. Here I describe a framework to overcome these challenges using a program of drone-enabled remote sensing measurements of solar-induced fluorescence (SIF) coupled with ground-based physiological studies to understand the determinants of photosynthesis within leaves, individual organisms and large landscapes. The Brown Platform for Autonomous Remote Sensing (BPAR) is a suite of sensors carried by a gas-powered helicopter drone. By conducting frequent, low-altitude flights BPAR can produce VNIR imaging spectroscopy time series with measurements separated by minutes to hours at ground sample distances of 1 cm. The talk will focus on how measurements of SIF at these spatial and temporal scales can be coupled with models to infer the rate of electron transport and carbon assimilation.

  13. Engineering iodine-doped carbon dots as dual-modal probes for fluorescence and X-ray CT imaging

    Directory of Open Access Journals (Sweden)

    Zhang M

    2015-11-01

    Full Text Available Miaomiao Zhang,1,* Huixiang Ju,2,* Li Zhang,1,* Mingzhong Sun,2 Zhongwei Zhou,2 Zhenyu Dai,3 Lirong Zhang,1 Aihua Gong,1 Chaoyao Wu,1 Fengyi Du1 1School of Medicine, Jiangsu University, Zhenjiang, People’s Republic of China; 2Department of Clinical Laboratory, Affiliated Yancheng Hospital, School of Medicine, Southeast University, Yancheng, Jiangsu, People’s Republic of China; 3Radiology Department, Affiliated Yancheng Hospital, School of Medicine, Southeast University, Yancheng, Jiangsu, People’s Republic of China *These authors contributed equally to this work Abstract: X-ray computed tomography (CT is the most commonly used imaging technique for noninvasive diagnosis of disease. In order to improve tissue specificity and prevent adverse effects, we report the design and synthesis of iodine-doped carbon dots (I-doped CDs as efficient CT contrast agents and fluorescence probe by a facile bottom-up hydrothermal carbonization process. The as-prepared I-doped CDs are monodispersed spherical nanoparticles (a diameter of ~2.7 nm with favorable dispersibility and colloidal stability in water. The aqueous solution of I-doped CDs showed wavelength-dependent excitation and stable photoluminescence similar to traditional carbon quantum dots. Importantly, I-doped CDs displayed superior X-ray attenuation properties in vitro and excellent biocompatibility. After intravenous injection, I-doped CDs were distributed throughout the body and excreted by renal clearance. These findings validated that I-doped CDs with high X-ray attenuation potency and favorable photoluminescence show great promise for biomedical research and disease diagnosis. Keywords: carbon dots, contrast agents, iodine-doped, CT imaging

  14. One-pot synthesis of polyamines improved magnetism and fluorescence Fe3O4-carbon dots hybrid NPs for dual modal imaging.

    Science.gov (United States)

    Li, Bo; Wang, Xudong; Guo, Yali; Iqbal, Anam; Dong, Yaping; Li, Wu; Liu, Weisheng; Qin, Wenwu; Chen, Shizhen; Zhou, Xin; Yang, Yunhuang

    2016-04-01

    A one-step hydrothermal method was developed to fabricate Fe3O4-carbon dots (Fe3O4-CDs) magnetic-fluorescent hybrid nanoparticles (NPs). Ferric ammonium citrate (FAC) was used as a cheap and nontoxic iron precursor and as the carbon source. Moreover, triethylenetetramine (TETA) was used to improve the adhesive strength of CDs on Fe3O4 and the fluorescence intensity of CDs. The prepared water-soluble hybrid NPs not only exhibit excellent superparamagnetic properties (Ms = 56.8 emu g(-1)), but also demonstrate excitation-independent photoluminescence for down-conversion and up-conversion at 445 nm. Moreover, the prepared water-soluble Fe3O4-CDs hybrid NPs have a dual modal imaging ability for both magnetic resonance imaging (MRI) and fluorescence imaging. PMID:26786182

  15. Field-scale fluorescence fingerprinting of biochar-borne dissolved organic carbon

    Science.gov (United States)

    Biochar continues to receive worldwide enthusiasm as means of augmenting recalcitrant organic carbon in agricultural soils. Realistic biochar amendment rate (typically less than 1 wt%) in the field scale, and loss by sizing, rain, and other transport events demand reliable methods to quantify the r...

  16. One-step synthesis of fluorescently labelled, single-walled carbon nanotubes.

    Science.gov (United States)

    Guaragno, Michelle L; Gottardi, Riccardo; Fedorchak, Morgan V; Roy, Abhijit; Kumta, Prashant N; Little, Steven R

    2015-12-18

    Single-walled carbon nanotubes (SWNTs) can be labelled with functional moieties that endow them with a number of unique characteristics, which can be applicable to biomedical applications such as imaging. Herein we describe a facile, one-step esterification process to functionalize SWNT with fluorescein. PMID:26458421

  17. Environmental Detection of Single-Walled Carbon Nanotubes Utilizing Near-Infrared Fluorescence

    Science.gov (United States)

    There are a growing number of applications for carbon nanotubes (CNT) in modern technologies and, subsequently, growth in production of CNT has expanded rapidly. Single-walled CNT (SWCNT) consist of a graphene sheet rolled up into a tube. With growing manufacture and use, the ...

  18. The brightness of colour.

    Directory of Open Access Journals (Sweden)

    David Corney

    Full Text Available BACKGROUND: The perception of brightness depends on spatial context: the same stimulus can appear light or dark depending on what surrounds it. A less well-known but equally important contextual phenomenon is that the colour of a stimulus can also alter its brightness. Specifically, stimuli that are more saturated (i.e. purer in colour appear brighter than stimuli that are less saturated at the same luminance. Similarly, stimuli that are red or blue appear brighter than equiluminant yellow and green stimuli. This non-linear relationship between stimulus intensity and brightness, called the Helmholtz-Kohlrausch (HK effect, was first described in the nineteenth century but has never been explained. Here, we take advantage of the relative simplicity of this 'illusion' to explain it and contextual effects more generally, by using a simple Bayesian ideal observer model of the human visual ecology. We also use fMRI brain scans to identify the neural correlates of brightness without changing the spatial context of the stimulus, which has complicated the interpretation of related fMRI studies. RESULTS: Rather than modelling human vision directly, we use a Bayesian ideal observer to model human visual ecology. We show that the HK effect is a result of encoding the non-linear statistical relationship between retinal images and natural scenes that would have been experienced by the human visual system in the past. We further show that the complexity of this relationship is due to the response functions of the cone photoreceptors, which themselves are thought to represent an efficient solution to encoding the statistics of images. Finally, we show that the locus of the response to the relationship between images and scenes lies in the primary visual cortex (V1, if not earlier in the visual system, since the brightness of colours (as opposed to their luminance accords with activity in V1 as measured with fMRI. CONCLUSIONS: The data suggest that perceptions

  19. Fluorescent turn-off/on bioassay for hemoglobin based on dual-emission carbon nanodots-graphene oxide system with multi-detection strategies.

    Science.gov (United States)

    Qu, Fei; Liu, Dongya; You, Jinmao

    2016-05-19

    As two members of the carbon materials family, carbon nanodots (CNDs) and graphene oxide (GO) possess many excellent optical properties resulting in a wide range of applications. In this work, the fluorescence of resultant dual-emission carbon nanodots (DECNDs) could be quenched by GO. In the presence of hemoglobin (Hb), the fluorescence would recover resulting from two interactions: one was the direct stacking effect of Hb on GO; the other one was that Hb could cover the surfaces of DECNDs; both of them would prevent the fluorescence quenching of DECNDs by GO. In the light of this mechanism, a novel fluorescent turn-off/on method has been developed for the detection of Hb based on DECNDs-GO system. By virtue of the dual emissions of these CNDs, it is noteworthy that both a single emission and ratiometric of dual emissions can be used to establish linear relationships of Hb: 0.05-300 nM (λem = 386 nm), 5-500 nM (λem = 530 nm), and 50-500 nM (I530/I410), with the corresponding limit of detection (LOD) as low as 20 pM, 2 nM and 20 nM, respectively. This present system is highly selective toward Hb over other proteins and this reliable method has been successfully applied for the detection of Hb in whole blood samples. PMID:27126790

  20. Stepwise Quenching of Exciton Fluorescence in Carbon Nanotubes by Single Molecule Reactions

    CERN Document Server

    Cognet, Laurent; Rocha, John-David R; Doyle, Condell D; Tour, James M; Weisman, R Bruce

    2007-01-01

    Single-molecule chemical reactions with individual single-walled carbon nanotubes were observed through near-infrared photoluminescence microscopy. The emission intensity within distinct submicrometer segments of single nanotubes changes in discrete steps after exposure to acid, base, or diazonium reactants. The steps are uncorrelated in space and time, and reflect the quenching of mobile excitons at localized sites of reversible or irreversible chemical attack. Analysis of step amplitudes reveals an exciton diffusional range of about 90 nanometers, independent of nanotube structure. Each exciton visits approximately 104 atomic sites during its lifetime, providing highly efficient sensing of local chemical and physical perturbations.

  1. Near-infrared fluorescent single walled carbon nanotube-chitosan composite: Interfacial strain transfer efficiency assessment

    Science.gov (United States)

    Mol Menamparambath, Mini; Arabale, Girish; Nikolaev, Pavel; Baik, Seunghyun; Arepalli, Sivaram

    2013-04-01

    Effective load transfer at the single walled carbon nanotube (SWCNT)-polymer interface is most desirable for mechanically reinforced polymer composites. Versatile layer-by-layer assembly technique achieved dispersion and uniform distribution of sodium carboxymethylcellulose (CMC)-solubilized SWCNTs within the polymer matrix. Electrostatic interaction between positively charged chitosan and negatively charged CMC facilitates design of an optically active biocompatible nanocomposite. Interfacial strain transfer efficiency of SWCNT-chitosan nanocomposite was assessed via SWCNT Raman and photoluminescence band shifts under uniaxial strain. Photoluminescence peak shift rates of individual semiconducting SWCNTs were investigated and compared with tight binding model calculations.

  2. Random-modulation cw lidar system for space-borne carbon dioxide remote sensing based on a high-brightness semiconductor laser

    OpenAIRE

    Esquivias Moscardo, Ignacio; Pérez Serrano, Antonio; Garcia Tijero, Jose Manuel; Faugeron, M.; Van Dijk, F.; Krakowski, M.; Kochem, G.; Traub, M.; Barbero González, Juan; Adamiec, Pawel; Ai, Xiao; Rarity, John; Quatrevalet, Mathieu; Ehret, Gerhard

    2014-01-01

    In this paper, we report on the progresses of the BRITESPACE Consortium in order to achieve space-borne LIDAR measurements of atmospheric carbon dioxide concentration based on an all semiconductor laser source at 1.57 ?m. The complete design of the proposed RM-CW IPDA LIDAR has been presented and described in detail. Complete descriptions of the laser module and the FSU have been presented. Two bended MOPAs, emitting at the sounding frequency of the on- and off- IPDA channels, have been propo...

  3. Bright Economic Prospects

    Institute of Scientific and Technical Information of China (English)

    Zhang Minqiu

    2004-01-01

    @@ India is expected to register an 8.2% growth rate for the 2003-04 fiscal year. The overall economic situation this year has been satisfactory despite the scaled down 6-6.5% growth rate for the new fiscal year due to oil price hikes, reduced monsoon volume and some 7% inflation. Judging from the following factors, bright prospects are in store for the country down the road.

  4. Enhanced sorption of mercury from compact fluorescent bulbs and contaminated water streams using functionalized multiwalled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Avinash; Vidyarthi, S.R. [Department of Chemical Engineering Harcourt Butler Technological Institute, Kanpur 208001, U.P. (India); Sankararamakrishnan, Nalini, E-mail: nalini@iitk.ac.in [Centre for Environmental Science and Engineering Indian Institute of Technology Kanpur, Kanpur 208016, U.P. (India)

    2014-06-01

    Highlights: • Oxidized (CNT-OX), CNT-I, CNT-S were prepared. • Capacity of CNT-S (151.5 mg/g) was higher than other CNTs. • Applied to the removal of Hg(II) from spiked and natural coal wash waters. • Applied to the removal of Hg(0) from compact fluorescent lamps. - Abstract: Three different functionalized multiwalled carbon nanotubes were prepared, namely, oxidized CNTs (CNT-OX), iodide incorporated MWCNT (CNT-I) and sulfur incorporated MWCNT (CNT-S). The as prepared adsorbents were structurally characterized by various spectral techniques like scanning electron microscopy (SEM), energy dispersive X-ray (EDAX), Brunauer, Emmett, and Teller (BET) surface area analyzer, Fourier transform infra red (FTIR) and Raman spectroscopy. Loading of iodide and sulfur was evident from the EDAX graphs. The adsorption properties of Hg{sup 2+} as a function of pH, contact time and initial metal concentration were characterized by Cold vapor AAS. The adsorption kinetics fitted the Pseudo second order kinetics and equilibrium was reached within 90 min. The experimental data were modeled with Langmuir, Freundlich, Dubinin-Redushkevich and Temkin isotherms and various isotherm parameters were evaluated. It was found that the mercury adsorption capacity for the prepared adsorbents were in the order of CNT-S > CNT-I > CNT-OX > CNT. Studies have been conducted to demonstrate the applicability of the sorbent toward the removal of Hg(0) from broken compact fluorescent light (CFL) bulbs and Hg(II) from contaminated water streams.

  5. Simultaneous tracking of drug molecules and carriers using aptamer-functionalized fluorescent superstable gold nanorod-carbon nanocapsules during thermo-chemotherapy

    Science.gov (United States)

    Wang, Xue-Wei; Gao, Wei; Fan, Huanhuan; Ding, Ding; Lai, Xiao-Fang; Zou, Yu-Xiu; Chen, Long; Chen, Zhuo; Tan, Weihong

    2016-04-01

    Controlling and monitoring the drug delivery process is critical to its intended therapeutic function. Many nanocarrier systems for drug delivery have been successfully developed. However, biocompatibility, stability, and simultaneously tracing drugs and nanocarriers present significant limitations. Herein, we have fabricated a multifunctional nanocomposite by coating the gold nanorod (AuNR) with a biocompatible, superstable and fluorescent carbon layer, obtaining the AuNR@carbon core-shell nanocapsule. In this system, the carbon shell, originally obtained in aqueous glucose solutions and, therefore, biocompatible in physiological environments, could be simply loaded with cell-specific aptamers and therapeutic molecules through π-π interactions, a useful tool for cancer-targeted cellular imaging and therapy. Moreover, such a stable and intrinsic fluorescence effect of the AuNR@carbon enabled simultaneous tracking of released therapeutic molecules and nanocarriers under thermo-chemotherapy. The AuNR@carbons had high surface areas and stable shells, as well as unique optical and photothermal properties, making them promising nanostructures for biomedical applications.Controlling and monitoring the drug delivery process is critical to its intended therapeutic function. Many nanocarrier systems for drug delivery have been successfully developed. However, biocompatibility, stability, and simultaneously tracing drugs and nanocarriers present significant limitations. Herein, we have fabricated a multifunctional nanocomposite by coating the gold nanorod (AuNR) with a biocompatible, superstable and fluorescent carbon layer, obtaining the AuNR@carbon core-shell nanocapsule. In this system, the carbon shell, originally obtained in aqueous glucose solutions and, therefore, biocompatible in physiological environments, could be simply loaded with cell-specific aptamers and therapeutic molecules through π-π interactions, a useful tool for cancer-targeted cellular imaging and

  6. Microwave heating of arginine yields highly fluorescent nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Philippidis, Aggelos [Foundation for Research and Technology-Hellas, Institute of Electronic Structure and Laser (Greece); Stefanakis, Dimitrios [University of Crete, Department of Chemistry (Greece); Anglos, Demetrios, E-mail: anglos@iesl.forth.gr [Foundation for Research and Technology-Hellas, Institute of Electronic Structure and Laser (Greece); Ghanotakis, Demetrios, E-mail: ghanotakis@chemistry.uoc.gr [University of Crete, Department of Chemistry (Greece)

    2013-01-15

    Brightly fluorescent nanoparticles were produced via a single-step, single-precursor procedure based on microwave heating of an aqueous solution of the amino acid arginine. Key structural and optical properties of the resulting Arg nanoparticles, Arg-dots, are reported and discussed with emphasis on the pH dependence of their fluorescence emission. The surface of the Arg-dots was functionalised through coupling to folic acid, opening up ways for connecting fluorescent nanoparticles to cancer cells. The generality and versatility of the microwave heating procedure was further demonstrated by the synthesis of different types of carbon nanoparticles, such as CE-dots, that were produced by use of citric acid and ethanolamine as precursors and compared to the Arg-dots.

  7. Microwave heating of arginine yields highly fluorescent nanoparticles

    International Nuclear Information System (INIS)

    Brightly fluorescent nanoparticles were produced via a single-step, single-precursor procedure based on microwave heating of an aqueous solution of the amino acid arginine. Key structural and optical properties of the resulting Arg nanoparticles, Arg-dots, are reported and discussed with emphasis on the pH dependence of their fluorescence emission. The surface of the Arg-dots was functionalised through coupling to folic acid, opening up ways for connecting fluorescent nanoparticles to cancer cells. The generality and versatility of the microwave heating procedure was further demonstrated by the synthesis of different types of carbon nanoparticles, such as CE-dots, that were produced by use of citric acid and ethanolamine as precursors and compared to the Arg-dots.

  8. DNA-stabilized silver nanoclusters and carbon nanoparticles oxide: A sensitive platform for label-free fluorescence turn-on detection of HIV-DNA sequences.

    Science.gov (United States)

    Ye, Yu-Dan; Xia, Li; Xu, Dang-Dang; Xing, Xiao-Jing; Pang, Dai-Wen; Tang, Hong-Wu

    2016-11-15

    Based on the remarkable difference between the interactions of carbon nanoparticles (CNPs) oxide with single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA), and the fact that fluorescence of DNA-stabilized silver nanoclusters (AgNCs) can be quenched by CNPs oxide, DNA-functionalized AgNCs were applied as label-free fluorescence probes and a novel fluorescence resonance energy transfer (FRET) sensor was successfully constructed for the detection of human immunodeficiency virus (HIV) DNA sequences. CNPs oxide were prepared with the oxidation of candle soot, hence it is simple, time-saving and low-cost. The strategy of dual AgNCs probes was applied to improve the detection sensitivity by using dual- probe capturing the same target DNA in a sandwich mode and as the fluorescence donor, and using CNPs oxide as the acceptor. In the presence of target DNA, a dsDNA hybrid forms, leading to the desorption of the ssDNA-AgNCs probes from CNPs oxide, and the recovering of fluorescence of the AgNCs in a HIV-DNA concentration-dependent manner. The results show that HIV-DNA can be detected in the range of 1-50nM with a detection limit of 0.40nM in aqueous buffer. The method is simple, rapid and sensitive with no need of labeled fluorescent probes, and moreover, the design of fluorescent dual-probe makes full use of the excellent fluorescence property of AgNCs and further improves the detection sensitivity. PMID:27295571

  9. Transduction of Glycan-Lectin Binding using Near Infrared Fluorescent Single Walled Carbon Nanotubes for Glycan Profiling

    Science.gov (United States)

    Reuel, Nigel; Ahn, Jin-Ho; Kim, Jong-Ho; Zhang, Jingqing; Boghossian, Ardemis; Mahal, Lara; Strano, Michael

    2012-02-01

    In this work, we demonstrate a sensor array employing recombinant lectins as glycan recognition sites tethered via Histidine tags to Ni2+ complexes that act as fluorescent quenchers for semi-conducting single walled carbon nanotubes embedded in a chitosan to measure binding kinetics of model glycans. Two higher-affined glycan-lectin pairs are explored: fucose (Fuc) to PA-IIL and N-acetylglucosamine (GlcNAc) to GafD. The dissociation constants (KD) for these pairs as free glycans (106 and 19 μM respectively) and streptavidin-tethered (142 and 50 μM respectively) were found. The absolute detection limit for the current platform was found to be 2 μg of glycosylated protein or 100 ng of free glycan to 20 μg of lectin. Glycan detection is demonstrated at the single nanotube level (GlcNAc to GafD). Over a population of 1000 nanotubes, 289 of the SWNT sensors had signals strong enough to yield kinetic information (KD of 250 ± 10 μM). We are also able to identify the locations of ``strong-transducers'' on the basis of dissociation constant (4 sensors with KD 5% quench response). The ability to pinpoint strong-binding, single sensors is promising to build a nanoarray of glycan-lectin transducers as a method to profile glycans without protein labeling or glycan liberation pretreatment steps.

  10. Fluorescent Carbon Quantum Dots Incorporated into Dye-Sensitized TiO2 Photoanodes with Dual Contributions.

    Science.gov (United States)

    Shi, Yan; Na, Yong; Su, Ting; Li, Liang; Yu, Jia; Fan, Ruiqing; Yang, Yulin

    2016-06-22

    Fluorescent carbon quantum dots (CQDs) were prepared through bottom-up synthesis, which possess excitation wavelength-dependent photoluminescence properties upon excitation by near visible light. For the first time, CQDs were incorporated into N719-sensitized TiO2 photoelectrodes as the electron-transport medium, presenting dual contributions to the photo-to-electrical energy conversion: 1) spectral response compensation for the dye-sensitized TiO2 film at around 400 nm was successfully observed in the incident photon-to-current conversion measurements; and 2) intensity modulated photocurrent/photovoltage spectroscopy showed that the electron transport time, charge collection efficiency, and electron diffusion length in the TiO2 electrode were all improved after CQDs incorporation. An example of using the CQDs- containing photoanode in a solar cell device resulted in enhancements of 32 % and 21 % for the short-circuit current density and photo-to-electrical conversion efficiency, respectively. PMID:27218888

  11. Fluorescence fluctuation immunoassay.

    Science.gov (United States)

    Elings, V B; Nicoli, D F; Briggs, J

    1983-01-01

    The homogeneous fluorescent immunoassay described above allows one to measure the brightness of fluorescently tagged carrier particles that are suspended in a background of free, unbound fluorescent sources. We have demonstrated the feasibility of our technique using a gentamicin competitive assay as well as idealized model systems. We have seen that the fluctuation-correlation method is able to discriminate against free background sources because each fluorescing particle in solution contributes to the correlation peak [Eq. (4)] with a weighting equal to the square of its respective intensity. Hence, a few very bright sources contribute disproportionately to the "signal" relative to many weak ones. To take advantage of this property, one would therefore design an assay that uses relatively larger carrier particles, each of which is capable of binding on the order of 10(3) to 10(4) tagged antibodies or antigens. Unfortunately, the nonlinear dependence of the correlation peak on the brightness of the fluorescing species causes the technique to be perturbed by carrier particle aggregation; the apparent bound fluorescence intensity increases with the extent of aggregation. The latter may be an unavoidable consequence of performing assays using raw blood serum, for example. The ultimate usefulness of this method will depend on its sensitivity and speed when applied to "real" assays of clinical significance. These characteristics will be influenced by a number of technical details. Given our limited experience with the method thus far, it would appear that its principal drawback is its relatively slow speed. In order to decrease the time needed for a reliable measurement, one must average the random fluctuations in the fluorescent intensity to zero more quickly. In principle, this can be accomplished by decreasing the shot noise by collecting a larger fraction of the fluorescent light, and increasing the sampling rate. The method requires rather complicated

  12. Analytical possibilities of different X-ray fluorescence systems for determination of trace elements in aqueous samples pre-concentrated with carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Marguí, E., E-mail: eva.margui@udg.edu [Department of Chemistry, University of Girona, Campus Montilivi, 17071 Girona (Spain); Zawisza, B.; Skorek, R. [Institute of Chemistry, University of Silesia, Szkolna 9, 40-006 Katowice (Poland); Theato, T. [SPECTRO Analytical Instruments GmbH, Boschstr. 10, 47533 Kleve (Germany); Queralt, I. [Laboratory of X-Ray Analytical Applications, Institute of Earth Sciences Jaume Almera, CSIC, Solé Sabarís s/n, 08028 Barcelona (Spain); Hidalgo, M. [Department of Chemistry, University of Girona, Campus Montilivi, 17071 Girona (Spain); Sitko, R. [Institute of Chemistry, University of Silesia, Szkolna 9, 40-006 Katowice (Poland)

    2013-10-01

    This study was aimed to achieve improved instrumental sensitivity and detection limits for multielement determination of V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Se, Pb and Cd in liquid samples by using different X-ray fluorescence (XRF) configurations (a benchtop energy-dispersive X-ray fluorescence spectrometer, a benchtop polarised energy-dispersive X-ray fluorescence spectrometer and a wavelength-dispersive X-ray fluorescence spectrometer). The preconcentration of metals from liquid solutions consisted on a solid-phase extraction using carbon nanotubes (CNTs) as solid sorbents. After the extraction step, the aqueous sample was filtered and CNTs with the absorbed elements were collected onto a filter paper which was directly analyzed by XRF. The calculated detection limits in all cases were in the low ng mL{sup −1} range. Nevertheless, results obtained indicate the benefits, in terms of sensitivity, of using polarized X-ray sources using different secondary targets in comparison to conventional XRF systems, above all if Cd determination is required. The developed methodologies, using the aforementioned equipments, have been applied for multielement determination in water samples from an industrial area of Poland. - Highlights: • Use of carbon nanotubes for preconcentration of V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Se, Pb and Cd • Combination of this preconcentration procedure with different XRF systems • Benefit of using polarized X-ray sources for trace element determination.

  13. Non-Covalent Functionalization of Carbon Nanotubes by Fluorescein-Polyethylene Glycol: Supramolecular Conjugates with pH Dependent Absorbance and Fluorescence

    OpenAIRE

    Nakayama-Ratchford, Nozomi; Bangsaruntip, Sarunya; Sun, Xiaoming; Welsher, Kevin; Dai, Hongjie

    2007-01-01

    We report the use of fluorescein-polyethylene glycol (Fluor-PEG) to non-covalently functionalize single-walled carbon nanotubes (SWNTs) for obtaining aqueous-soluble nanotube conjugates (Fluor-PEG/SWNT) and simultaneously affording fluorescence labels to nanotubes. We find serendipitously that fluorescein, a widely used fluorophore, can strongly adsorb onto the sidewall of the SWNTs likely via π-stacking, and the hydrophilic PEG chain imparts high aqueous solubility. Interaction between fluor...

  14. A unique "turn-on" fluorescence signalling strategy for highly specific detection of ascorbic acid using carbon dots as sensing probe.

    Science.gov (United States)

    Fong, Jessica Fung Yee; Chin, Suk Fun; Ng, Sing Muk

    2016-11-15

    Carbon dots (CDs) that showed strong blue fluorescence were successfully synthesised from sodium alginate via furnace pyrolysis. The single step pyrolytic synthesis was simple to perform while yielded CDs with high photostability, good water solubility and minimum by-products. In order to design the probe with "turn-on" sensing capability, the CDs were screened against a series of metal cations to first "turn-off" the fluorescence. It was found that ferric ions (Fe(3+)) were most responsive and effective in quenching the fluorescence of CDs. Based on this observation, the conditioning of the probe was performed to ensure the fluorescence was completely quenched, while not overloading the system with Fe(3+). At the optimised condition, the CDs-Fe(3+) mixture served as a highly specific detection probe for ascorbic acid (AA). The analytical potential of the probe was evaluated and showed a good linear range of response for AA concentration of 24-40μg/mL. The selectivity study against other possible co-existing species was carried out and proved that our unique "turn-on" fluorescence signalling strategy was highly effective and selective towards AA as the target analyte. The probe was demonstrated for quantification of AA in real samples, which was the commercially available vitamin C supplement. The result showed good accuracy with minimum deviation from standard method adopted for validation purpose. PMID:27290666

  15. 碳纳米管-苯胺电荷转移复合物中的胺荧光淬灭效应%Quenching Effects of Amine on Fluorescence of Carbon Nanotube-Aniline Charge Transfer Complex

    Institute of Scientific and Technical Information of China (English)

    SUN Xu-feng; WANG Yu; JIN Wei-jun

    2005-01-01

    Under refluxing, carbon nanotube (CNT) and aniline (An) can form the charge transfer complex (CTC) of CNT-An.The corresponding fluorescence emission peaks lied at 564nm and 606nm, respectively, with the excitation wavelength of 516nm in the acetone solution. The quenching effects of various amines on CNT- An CTC fluorescence were investigated in detail.

  16. Quantitative measurement of brightness from living cells in the presence of photodepletion.

    Directory of Open Access Journals (Sweden)

    Kwang-Ho Hur

    Full Text Available The brightness of fluorescently labeled proteins provides an excellent marker for identifying protein interactions in living cells. Quantitative interpretation of brightness, however, hinges on a detailed understanding of the processes that affect the signal fluctuation of the fluorescent label. Here, we focus on the cumulative influence of photobleaching on brightness measurements in cells. Photobleaching within the finite volume of the cell leads to a depletion of the population of fluorescently labeled proteins with time. The process of photodepletion reduces the fluorescence signal which biases the analysis of brightness data. Our data show that even small reductions in the signal can introduce significant bias into the analysis of the data. We develop a model that quantifies the bias and introduce an analysis method that accurately determines brightness in the presence of photodepletion as verified by experiments with mammalian and yeast cells. In addition, photodepletion experiments with the fluorescent protein EGFP reveal the presence of a photoconversion process, which leads to a marked decrease in the brightness of the EGFP protein. We also identify conditions where the effect of EGFP's photoconversion on brightness experiments can be safely ignored.

  17. Quantitative Measurement of Brightness from Living Cells in the Presence of Photodepletion

    Science.gov (United States)

    Berk, Serkan; Angert, C. Isaac; Chen, Yan; Mueller, Joachim D.

    2014-01-01

    The brightness of fluorescently labeled proteins provides an excellent marker for identifying protein interactions in living cells. Quantitative interpretation of brightness, however, hinges on a detailed understanding of the processes that affect the signal fluctuation of the fluorescent label. Here, we focus on the cumulative influence of photobleaching on brightness measurements in cells. Photobleaching within the finite volume of the cell leads to a depletion of the population of fluorescently labeled proteins with time. The process of photodepletion reduces the fluorescence signal which biases the analysis of brightness data. Our data show that even small reductions in the signal can introduce significant bias into the analysis of the data. We develop a model that quantifies the bias and introduce an analysis method that accurately determines brightness in the presence of photodepletion as verified by experiments with mammalian and yeast cells. In addition, photodepletion experiments with the fluorescent protein EGFP reveal the presence of a photoconversion process, which leads to a marked decrease in the brightness of the EGFP protein. We also identify conditions where the effect of EGFP's photoconversion on brightness experiments can be safely ignored. PMID:24820174

  18. High brightness electron sources

    International Nuclear Information System (INIS)

    High energy physics accelerators and free electron lasers put increased demands on the electron beam sources. This paper describes the present research on attaining intense bright electron beams using photoinjectors. Recent results from the experimental programs will be given. The performance advantages and difficulties presently faced by researchers will be discussed, and the following topics will be covered. Progress has been made in photocathode materials, both in lifetime and quantum efficiency. Cesium telluride has demonstrated significantly longer lifetimes than cesium antimonide at 10-8 torr. However, the laser system is more difficult because cesium telluride requires quadrupled YLF instead of the doubled YLF required for cesium antimonide. The difficulty in using photoinjectors is primarily the drive laser, in particular the amplitude stability. Finally, emittance measurements of photoinjector systems can be complicated by the non-thermal nature of the electron beam. An example of the difficulty in measuring beam emittance is given

  19. Highly fluorescent carbon dots as selective and sensitive "on-off-on" probes for iron(III) ion and apoferritin detection and imaging in living cells.

    Science.gov (United States)

    Han, Cuiping; Wang, Ru; Wang, Keying; Xu, Huiting; Sui, Meirong; Li, Jingjing; Xu, Kai

    2016-09-15

    Highly blue luminescent nitrogen-doped carbon dots (N-CDs) with a fluorescence quantum yield of 42.3% were prepared by an efficient one-step pyrolytic route from ethylenediaminetetraacetic acid and urea. The as-synthesized N-CDs were demonstrated as an effective fluorescent probe for label-free, selective and sensitive recognition of Fe(3+) with a linear range of 0.5μM to 2mM and a detection limit of 13.6nM due to Fe(3+)-quenched fluorescence (turn-off). The quenched fluorescence could be turned on after the addition of apoferritin owing to the removal of ferric species from the surface of N-CDs by apoferritin, making complex N-CDs/Fe(3+) a selective apoferritin probe with a linear range of 0.1-25μM and a detection limit as low as 2.6nM. In addition, the application of this novel N-CDs-based probe for imaging Fe(3+) ions and apoferritin in living cells suggest that this sensing system has great potential applications in biosensing, bioimaging, and many other fields. PMID:27131995

  20. Nitrogen-rich functional groups carbon nanoparticles based fluorescent pH sensor with broad-range responding for environmental and live cells applications.

    Science.gov (United States)

    Shi, Bingfang; Su, Yubin; Zhang, Liangliang; Liu, Rongjun; Huang, Mengjiao; Zhao, Shulin

    2016-08-15

    A nitrogen-rich functional groups carbon nanoparticles (N-CNs) based fluorescent pH sensor with a broad-range responding was prepared by one-pot hydrothermal treatment of melamine and triethanolamine. The as-prepared N-CNs exhibited excellent photoluminesence properties with an absolute quantum yield (QY) of 11.0%. Furthermore, the N-CNs possessed a broad-range pH response. The linear pH response range was 3.0 to 12.0, which is much wider than that of previously reported fluorescent pH sensors. The possible mechanism for the pH-sensitive response of the N-CNs was ascribed to photoinduced electron transfer (PET). Cell toxicity experiment showed that the as-prepared N-CNs exhibited low cytotoxicity and excellent biocompatibility with the cell viabilities of more than 87%. The proposed N-CNs-based pH sensor was used for pH monitoring of environmental water samples, and pH fluorescence imaging of live T24 cells. The N-CNs is promising as a convenient and general fluorescent pH sensor for environmental monitoring and bioimaging applications. PMID:27085956

  1. Mixotrophic growth of two thermophilic Methanosarcina strains, Methanosarcina thermophila TM-1 and Methanosarcina sp. SO-2P, on methanol and hydrogen/carbon dioxide

    DEFF Research Database (Denmark)

    Mladenovska, Zuzana; Ahring, Birgitte Kiær

    1997-01-01

    Two thermophilic strains, Methanosarcina thermophila TM-1 and Methanosarcina sp. SO-2P, were capable of mixotrophic growth on methanol and H-2/CO2. Activated carbon was, however, found to be necessary to support good growth. Both strains used hydrogen and methanol simultaneously. When methanol was...... depleted, hydrogen utilization continued and methane was further produced with concurrent cell growth. UV epifluorescence microscopy revealed that aggregates of both strains exhibited a bright red fluorescence besides the usual blue-green fluorescence....

  2. Spectrally resolved multidepth fluorescence imaging

    Science.gov (United States)

    Luo, Yuan; Zervantonakis, Ioannis K.; Oh, Se Baek; Kamm, Roger D.; Barbastathis, George

    2011-09-01

    We present a multicolor fluorescence imaging modality to visualize in real-time tissue structures emitting multispectral fluorescent light from different focal depths. Each designated spectrum of fluorescent emission from a specific depth within a volumetric tissue is probed by a depth-spectrum selective holographic grating. The grating for each fluorescent color are multiplexed within a volume hologram, which enables simultaneously obtaining multicolored fluorescent information at different depths within a biological tissue sample. We demonstrate the imaging modality's ability to obtain laser-induced multicolored fluorescence images of a biological sample from different depths without scanning. We also experimentally demonstrate that the imaging modality can be simultaneously operated at both fluorescent and bright field modes to provide complementary information of volumetric tissue structures at different depths in real-time.

  3. Biomimetic synthesis of needle-like fluorescent calcium phosphate/carbon dot hybrid composites for cell labeling and copper ion detection.

    Science.gov (United States)

    Guo, Shanshan; Lu, Shousi; Xu, Pingxiang; Ma, Yi; Zhao, Liang; Zhao, Yuming; Gu, Wei; Xue, Ming

    2016-05-01

    Herein, we report a biomimetic method to synthesize needle-like calcium phosphate (CaP) with dimensions of ∼130 nm length and ∼30 nm width using carbon dots (CDs) and sodium carboxymethylcellulose as dual templates. In addition to acting as the template, the CDs enable the CaP/CDs hybrid composites to emit blue fluorescence under UV excitation. Moreover, the prepared CaP/CDs exhibited a negligible cytotoxicity towards HeLa cells. The potential of these CaP/CDs as a fluorescent probe for cell labeling was tested. In addition, it was demonstrated that the CaP/CDs were capable of selective detection of copper ions in drinking water. PMID:27052495

  4. Facile and ultrasensitive fluorescence sensor platform for tumor invasive biomaker β-glucuronidase detection and inhibitor evaluation with carbon quantum dots based on inner-filter effect.

    Science.gov (United States)

    Lu, Shuaimin; Li, Guoliang; Lv, Zhengxian; Qiu, Nannan; Kong, Weiheng; Gong, Peiwei; Chen, Guang; Xia, Lian; Guo, Xiaoxi; You, Jinmao; Wu, Yongning

    2016-11-15

    Early detection and diagnosis have great practical significances for the effective prevention and treatment of cancer. In this study, we developed a novel, facile and ultra-sensitive fluorescence assay for the determination of tumor invasive biomarker β-glucuronidase (GLU) based on the inner-filter effect (IFE). The nitrogen-doped carbon quantum dots (N-CQDs) with green photoluminescence were employed as the fluorophore in IFE, and 4-nitrophenyl-β-D-glucuronide (PNPG) was used to act as GLU substrate, and GLU catalytic product (p-nitrophenol (PNP)) was capable of acting as the robust absorber in IFE to turn off the fluorescence of N-CQDs due to the complementary overlap between the absorption of PNP and the excitation of N-CQDs. Thus, signal of GLU activity could be recorded by the fluorescence intensity of N-CQDs. Unlike other fluorescence sensing mechanism such as fluorescence resonance energy transfer (FRET) or photoinduced electron transfer (PET), IFE has no requirement for electron or energy transfer process or any chemical modification of fluorophore, which makes our assay more flexible and simple. The proposed method exhibited a good linear relationship from 1UL(-1) to 60UL(-1) (R(2)=0.9967) with a low detection limit of 0.3UL(-1). This method was also successfully applied to the analysis of serum samples and the inhibitor screening from natural product. The developed sensor platform was proven to be reliable, facile, sensitive, and selective, making it promising as a candidate for GLU activity detection in clinic tumor diagnose and anti-tumor drug screening. PMID:27196253

  5. Relation of Chlorophyll Fluorescence Sensitive Reflectance Ratios to Carbon FluxMeasurements ofMontanne Grassland and Norway Spruce Forest Ecosystems in the Temperate Zone

    Czech Academy of Sciences Publication Activity Database

    Ač, Alexander; Malenovský, Z.; Urban, Otmar; Hanuš, Jan; Zitová, Martina; Navrátil, M.; Vráblová, M.; Olejníčková, Julie; Špunda, V.; Marek, Michal V.

    2012-01-01

    Roč. 2012, č. 2012 (2012), s. 1-13. ISSN 1537-744X R&D Projects: GA MŽP(CZ) SP/2D1/70/08; GA MŽP(CZ) SP/2D1/93/07; GA MŠk(CZ) LM2010007; GA MŠk(CZ) ED1.1.00/02.0073 Institutional research plan: CEZ:AV0Z60870520 Keywords : Chlorophyll fluorescence * carbon flux * forest ecosystems * Norway Spruce * temperate zone Subject RIV: EH - Ecology, Behaviour Impact factor: 1.730, year: 2012

  6. Gold nanorod@silica-carbon dots as multifunctional phototheranostics for fluorescence and photoacoustic imaging-guided synergistic photodynamic/photothermal therapy

    Science.gov (United States)

    Jia, Qingyan; Ge, Jiechao; Liu, Weimin; Liu, Sha; Niu, Guangle; Guo, Liang; Zhang, Hongyan; Wang, Pengfei

    2016-06-01

    Phototheranostics, which is the application of light in the diagnostic imaging and therapy of cancer, has shown great promise for multimodal cancer imaging and effective therapy. Herein, we developed multifunctional gold nanorod@silica-carbon dots (GNR@SiO2-CDs) as a phototheranostic agent by incorporating carbon dots (CDs) with gold nanorods (GNRs), using SiO2 as a scaffold. In GNR@SiO2-CDs, the GNRs act as both photoacoustic (PA) imaging and photothermal therapy (PTT) agents, and the CDs serve as fluorescence (FL) imaging and photodynamic therapy (PDT) agents. The introduction of SiO2 not only improves the chemical stability of the GNRs and CDs in the physiological environment but also prevents the absolute quenching of the fluorescence of the CDs by GNRs. These collective properties make GNR@SiO2-CDs a novel phototheranostic agent, in which high sensitivity and good spatial resolution of FL/PA imaging can be achieved to guide PDT/PTT treatments through i.v. administration. The combination of PDT and PTT proved to be more efficient in killing cancer cells compared to PDT or PTT alone under a low dose of laser irradiation (therapies.Phototheranostics, which is the application of light in the diagnostic imaging and therapy of cancer, has shown great promise for multimodal cancer imaging and effective therapy. Herein, we developed multifunctional gold nanorod@silica-carbon dots (GNR@SiO2-CDs) as a phototheranostic agent by incorporating carbon dots (CDs) with gold nanorods (GNRs), using SiO2 as a scaffold. In GNR@SiO2-CDs, the GNRs act as both photoacoustic (PA) imaging and photothermal therapy (PTT) agents, and the CDs serve as fluorescence (FL) imaging and photodynamic therapy (PDT) agents. The introduction of SiO2 not only improves the chemical stability of the GNRs and CDs in the physiological environment but also prevents the absolute quenching of the fluorescence of the CDs by GNRs. These collective properties make GNR@SiO2-CDs a novel phototheranostic agent

  7. Chlorophyll fluorescence analysis and imaging in plant stress and disease

    Energy Technology Data Exchange (ETDEWEB)

    Daley, P.F.

    1994-12-01

    Quantitative analysis of chlorophyll fluorescence transients and quenching has evolved rapidly in the last decade. Instrumentation capable of fluorescence detection in bright actinic light has been used in conjunction with gas exchange analysis to build an empirical foundation relating quenching parameters to photosynthetic electron transport, the state of the photoapparatus, and carbon fixation. We have developed several instruments that collect video images of chlorophyll fluorescence. Digitized versions of these images can be manipulated as numerical data arrays, supporting generation of quenching maps that represent the spatial distribution of photosynthetic activity in leaves. We have applied this technology to analysis of fluorescence quenching during application of stress hormones, herbicides, physical stresses including drought and sudden changes in humidity of the atmosphere surrounding leaves, and during stomatal oscillations in high CO{sub 2}. We describe a recently completed portable fluorescence imaging system utilizing LED illumination and a consumer-grade camcorder, that will be used in long-term, non-destructive field studies of plant virus infections.

  8. Simple Approach to Synthesize Amino-Functionalized Carbon Dots by Carbonization of Chitosan.

    Science.gov (United States)

    Liu, Xin; Pang, Jinhui; Xu, Feng; Zhang, Xueming

    2016-01-01

    Carbon dots (CDs) as a new series of fluorescent nanomaterials have drawn great attention in recent years owning to their unique properties. In this paper, a simple carbonization approach to synthesize amino-functionalized CDs was developed by using chitosan as the carbon precursor. The as-prepared CDs possessed desirable amino function group on their surface and exhibited bright luminescence with absolute quantum yield (QY) of 4.34%, excitation-, pH-dependent and up-conversion fluorescence behaviors. Furthermore, we have investigated the cytotoxicity and biocompatibility of the as-prepared CDs, which demonstrated that the as-prepared CDs have the potential applications in biosensing, cellular imaging and drug delivery. PMID:27492748

  9. Simultaneous detection of pathogenic bacteria using an aptamer based biosensor and dual fluorescence resonance energy transfer from quantum dots to carbon nanoparticles

    International Nuclear Information System (INIS)

    We report on a method for simultaneous detection of the pathogens Vibrio parahaemolyticus and Salmonella typhimurium. It is based on dual fluorescence resonance energy transfer (FRET) from green-emitting quantum-dots (gQDs) and red-emitting quantum-dots (rQDs) as donors, and on novel amorphous carbon nanoparticles (CNPs) that act as acceptor. The gQDs were modified with an aptamer (Apt 1) recognizing V. parahaemolyticus, and the rQDs with an aptamer (Apt 2) recognizing S. typhimurium. The fluorescence of both QDs is strongly quenched in the presence of CNPs. However, on addition of the target analytes, the QDs-aptamer-target complex is formed and quenching by CNPs is suppressed. The fluorescence of the QDs is linearly proportional to the concentration of the two pathogens in the range from 50 to 106 cfu·mL−1, with detection limits as low as 25 cfu·mL−1 for V. parahaemolyticus, and of 35 cfu·mL−1 for S. typhimurium. The assay was applied to real food samples, and the results were consistent with the results obtained with plate counting methods. We presume that this strategy can be extended to the detection of other pathogenic bacteria and biomolecules by simply substituting the aptamer. (author)

  10. Antioxidative, hemocompatible, fluorescent carbon nanodots from an "end-of-pipe" agricultural waste: exploring its new horizon in the food-packaging domain.

    Science.gov (United States)

    Das Purkayastha, Manashi; Manhar, Ajay Kumar; Das, Vijay Kumar; Borah, Anjan; Mandal, Manabendra; Thakur, Ashim Jyoti; Mahanta, Charu Lata

    2014-05-21

    The attention of researchers is burgeoning toward oilseed press-cake valorization for its high protein content. Protein removal from oil-cakes generates large quantities of fibrous residue (oil-and-protein spent meal) as a byproduct, which currently has very limited practical utility. In the wake of increasing awareness in waste recycling, a simple environmentally benign hydrothermal carbonization process to convert this "end-of-pipe" waste (spent meal) into antioxidative, hemocompatible, fluorescent carbonaceous nanoparticles (FCDs) has been described. In the present investigation, an interesting application of FCDs in fabricating low-cost rapeseed protein-based fluorescent film, with improved antioxidant potential (17.5-19.3-fold) and thermal stability has been demonstrated. The nanocomposite film could also be used as forgery-proof packaging due to its photoluminescence property. For assessing the feasibility of antioxidative FCDs in real food systems, a comparative investigation was further undertaken to examine the effect of such nanocarbon-loaded composite film on the oxidative shelf life of rapeseed oil. Oil samples packed in nanocomposite film sachets showed significant delay in oxidative rancidity compared to those packed in pristine protein-film sachet (free fatty acids, peroxide value, and thiobarbituric acid-reactive substances reduced up to 1.4-, 2-, and 1.2-fold, respectively). The work presents a new concept of biobased fluorescent packaging and avenues for harnessing this potent waste. PMID:24784501

  11. A Highly Selective and Sensitive Fluorescence Detection Method of Glyphosate Based on an Immune Reaction Strategy of Carbon Dot Labeled Antibody and Antigen Magnetic Beads.

    Science.gov (United States)

    Wang, Duo; Lin, Bixia; Cao, Yujuan; Guo, Manli; Yu, Ying

    2016-08-01

    A sensitive fluorescence detection method for glyphosate (GLY) was established based on immune reaction. First, carbon dot labeled antibodies (lgG-CDs) which were able to specifically identify glyphosate were prepared with the environmentally friendly carbon dots (CDs) and glyphosate antibody (lgG). lgG-CDs could be used to in situ visualize the distribution of glyphosate in plant tissues. In order to eliminate the effects of excess lgG-CDs on the determination of GLY, antigen magnetic beads Fe3O4-GLY based on magnetic nanoparticles Fe3O4 and glyphosate were constructed and utilized to couple with the excess lgG-CDs. After magnetic separation to remove antigen magnetic beads, there was a linear relationship between the fluorescence intensity of lgG-CDs and the logarithmic concentration of glyphosate in the range of 0.01-80 μg/mL with a detection limit of 8 ng/mL. The method was used for the detection of glyphosate in Pearl River water, tea, and soil samples with satisfactory recovery ratio between 87.4% and 103.7%. PMID:27403652

  12. The determination, by x-ray-fluorescence spectrometry, of gold, silver, and base metals on activated carbon

    International Nuclear Information System (INIS)

    The method proposed involves ashing of the sample at a low temperature in a muffle furnace, mixing of the ash with alumina and boric acid in a Siebtechnik mill, and briquetting of the mixture. The elements are measured in the briquette by the use of x-ray fluorescence spectrometry. The detailed laboratory method is given in an appendix

  13. Interpreting seasonal changes in the carbon balance of southern Amazonia using measurements of XCO2 and chlorophyll fluorescence from GOSAT

    NARCIS (Netherlands)

    Parazoo, Nicholas C.; Bowman, Kevin; Frankenberg, Christian; Lee, Jung-Eun; Fisher, Joshua B.; Worden, John; Jones, Dylan B. A.; Berry, Joseph; Collatz, G. James; Baker, Ian T.; Jung, Martin; Liu, Junjie; Osterman, Gregory; O'Dell, Chris; Sparks, Athena; Butz, Andre; Guerlet, Sandrine; Yoshida, Yukio; Chen, Huilin; Gerbig, Christoph

    2013-01-01

    Amazon forests exert a major influence on the global carbon cycle, but quantifying the impact is complicated by diverse landscapes and sparse data. Here we examine seasonal carbon balance in southern Amazonia using new measurements of column-averaged dry air mole fraction of CO2 (XCO2) and solar ind

  14. Diagnostics of Carbon Nanotube Formation in a Laser Produced Plume: An Investigation of the Metal Catalyst by Laser Ablation Atomic Fluorescence Spectroscopy

    Science.gov (United States)

    deBoer, Gary; Scott, Carl

    2003-01-01

    Carbon nanotubes, elongated molecular tubes with diameters of nanometers and lengths in microns, hold great promise for material science. Hopes for super strong light-weight material to be used in spacecraft design is the driving force behind nanotube work at JSC. The molecular nature of these materials requires the appropriate tools for investigation of their structure, properties, and formation. The mechanism of nanotube formation is of particular interest because it may hold keys to controlling the formation of different types of nanotubes and allow them to be produced in much greater quantities at less cost than is currently available. This summer's work involved the interpretation of data taken last summer and analyzed over the academic year. The work involved diagnostic studies of carbon nanotube formation processes occurring in a laser-produced plume. Laser ablation of metal doped graphite to produce a plasma plume in which carbon nanotubes self assemble is one method of making carbon nanotube. The laser ablation method is amenable to applying the techniques of laser spectroscopy, a powerful tool for probing the energies and dynamics of atomic and molecular species. The experimental work performed last summer involved probing one of the metal catalysts, nickel, by laser induced fluorescence. The nickel atom was studied as a function of oven temperature, probe laser wavelength, time after ablation, and position in the laser produced plume. This data along with previously obtained data on carbon was analyzed over the academic year. Interpretations of the data were developed this summer along with discussions of future work. The temperature of the oven in which the target is ablated greatly influences the amount of material ablated and the propagation of the plume. The ablation conditions and the time scale of atomic and molecular lifetimes suggest that initial ablation of the metal doped carbon target results in atomic and small molecular species. The metal

  15. Investigating the usefulness of satellite-derived fluorescence data in inferring gross primary productivity within the carbon cycle data assimilation system

    Science.gov (United States)

    Koffi, E. N.; Rayner, P. J.; Norton, A. J.; Frankenberg, C.; Scholze, M.

    2015-07-01

    Simulations of carbon fluxes with terrestrial biosphere models still exhibit significant uncertainties, in part due to the uncertainty in model parameter values. With the advent of satellite measurements of solar induced chlorophyll fluorescence (SIF), there exists a novel pathway for constraining simulated carbon fluxes and parameter values. We investigate the utility of SIF in constraining gross primary productivity (GPP). As a first test we assess whether SIF simulations are sensitive to important parameters in a biosphere model. SIF measurements at the wavelength of 755 nm are simulated by the Carbon-Cycle Data Assimilation System (CCDAS) which has been augmented by the fluorescence component of the Soil Canopy Observation, Photochemistry and Energy fluxes (SCOPE) model. Idealized sensitivity tests of the SCOPE model stand-alone indicate strong sensitivity of GPP to the carboxylation capacity (Vcmax) and of SIF to the chlorophyll AB content (Cab) and incoming short wave radiation. Low sensitivity is found for SIF to Vcmax, however the relationship is subtle, with increased sensitivity under high radiation conditions and lower Vcmax ranges. CCDAS simulates well the patterns of satellite-measured SIF suggesting the combined model is capable of ingesting the data. CCDAS supports the idealized sensitivity tests of SCOPE, with SIF exhibiting sensitivity to Cab and incoming radiation, both of which are treated as perfectly known in previous CCDAS versions. These results demonstrate the need for careful consideration of Cab and incoming radiation when interpreting SIF and the limitations of utilizing SIF to constrain Vcmax in the present set-up in the CCDAS system.

  16. Fluorescence fluctuation spectroscopy (FFS), pt.A

    CERN Document Server

    Tetin, Sergey

    2014-01-01

    This new volume of Methods in Enzymology continues the legacy of this premier serial by containing quality chapters authored by leaders in the field. This volume covers Fluorescence Fluctuation SpectroscopyContains chapters on such topics as Time-integrated fluorescence cumulant analysis, Pulsed Interleaved Excitation, and raster image correlation spectroscopy and number and brightness analysis.Continues the legacy of this premier serial with quality chapters authored by leaders in the fieldCovers fluorescence fluctuation spectroscopyContains chapte

  17. Photosynthetic acclimation to photon irradiance and its relation to chlorophyll fluorescence and carbon assimilation in the halotolerant green alga Dunaliella viridis.

    Science.gov (United States)

    Gordillo, F J; Jiménez, C; Chavarría, J; Xavier Niell, F

    2001-01-01

    This work describes the long-term acclimation of the halotolerant microalga Dunaliella viridis to different photon irradiance, ranging from darkness to 1500 mumol m(-2) s(-1). In order to assess the effects of long-term photoinhibition, changes in oxygen production rate, pigment composition, xanthophyll cycle and in vivo chlorophyll fluorescence using the saturating pulse method were measured. Growth rate was maximal at intermediate irradiance (250 and 700 mumol m(-2) s(-1)). The increase in growth irradiance from 700 to 1500 mumol m(-2) s(-1) did not lead to further significant changes in pigment composition or EPS, indicating saturation in the pigment response to high light. Changes in Photosystem II optimum quantum yield (F(v)/F(m)) evidenced photoinhibition at 700 and especially at 1500 mumol m(-2) s(-1). The relation between photosynthetic electron flow rate and photosyntetic O(2) evolution was linear for cultures in darkness shifting to curvilinear as growth irradiance increased, suggesting the interference of the energy dissipation processes in oxygen evolution. Carbon assimilation efficiencies were studied in relation to changes in growth rate, internal carbon and nitrogen composition, and organic carbon released to the external medium. All illuminated cultures showed a high capability to maintain a C:N ratio between 6 and 7. The percentage of organic carbon released to the external medium increased to its maximum under high irradiance (1500 mumol m(-2) s(-1)). These results suggest that the release of organic carbon could act as a secondary dissipation process when the xanthophyll cycle is saturated. PMID:16228345

  18. Teradiode's high brightness semiconductor lasers

    Science.gov (United States)

    Huang, Robin K.; Chann, Bien; Burgess, James; Lochman, Bryan; Zhou, Wang; Cruz, Mike; Cook, Rob; Dugmore, Dan; Shattuck, Jeff; Tayebati, Parviz

    2016-03-01

    TeraDiode is manufacturing multi-kW-class ultra-high brightness fiber-coupled direct diode lasers for industrial applications. A fiber-coupled direct diode laser with a power level of 4,680 W from a 100 μm core diameter, lasers. The fiber-coupled output corresponds to a Beam Parameter Product (BPP) of 3.5 mm-mrad and is the lowest BPP multi-kW-class direct diode laser yet reported. This laser is suitable for industrial materials processing applications, including sheet metal cutting and welding. This 4-kW fiber-coupled direct diode laser has comparable brightness to that of industrial fiber lasers and CO2 lasers, and is over 10x brighter than state-of-the-art direct diode lasers. We have also demonstrated novel high peak power lasers and high brightness Mid-Infrared Lasers.

  19. Magnetic/NIR-responsive drug carrier, multicolor cell imaging, and enhanced photothermal therapy of gold capped magnetite-fluorescent carbon hybrid nanoparticles

    Science.gov (United States)

    Wang, Hui; Cao, Guixin; Gai, Zheng; Hong, Kunlun; Banerjee, Probal; Zhou, Shuiqin

    2015-04-01

    This paper reports a type of multifunctional hybrid nanoparticle (NP) composed of gold nanocrystals coated on and/or embedded in a magnetite-fluorescent porous carbon core-shell NP template (Fe3O4@PC-CDs-Au) for biomedical applications, including magnetic/NIR-responsive drug release, multicolor cell imaging, and enhanced photothermal therapy. The synthesis of the Fe3O4@PC-CDs-Au NPs firstly involves the preparation of core-shell template NPs with magnetite nanocrystals clustered in the cores and fluorescent carbon dots (CDs) embedded in a porous carbon shell, followed by an in situ reduction of silver ions (Ag+) loaded in the porous carbon shell and a subsequent replacement of Ag NPs with Au NPs through a galvanic replacement reaction using HAuCl4 as a precursor. The Fe3O4@PC-CDs-Au NPs can enter the intracellular region and light up mouse melanoma B16F10 cells in multicolor mode. The porous carbon shell, anchored with hydrophilic hydroxyl/carboxyl groups, endows the Fe3O4@PC-CDs-Au NPs with excellent stability in the aqueous phase and a high loading capacity (719 mg g-1) for the anti-cancer drug doxorubicin (DOX). The superparamagnetic Fe3O4@PC-CDs-Au NPs with a saturation magnetization of 23.26 emu g-1 produce localized heat under an alternating magnetic field, which triggers the release of the loaded drug. The combined photothermal effects of the Au nanocrystals and the CDs on/in the carbon shell can not only regulate the release rate of the loaded drug, but also efficiently kill tumor cells under NIR irradiation. Benefitting from their excellent optical properties, their magnetic field and NIR light-responsive drug release capabilities and their enhanced photothermal effect, such nanostructured Fe3O4@PC-CDs-Au hybrid NPs are very promising for simultaneous imaging diagnostics and high efficacy therapy.This paper reports a type of multifunctional hybrid nanoparticle (NP) composed of gold nanocrystals coated on and/or embedded in a magnetite-fluorescent porous

  20. The EUVE bright source list

    Science.gov (United States)

    Stroozas, B.; Mcdonald, K.; Antia, B.; Mcdonald, J.; Wiercigroch, A.

    1993-01-01

    Initial results for bright extreme ultraviolet sources discovered during the EUVE all-sky and deep ecliptic surveys have been published as a Bright Source List (BSL) and released to the astronomical community with a recent NASA research announcement (NRA 93-OSS-02, Appendix F). This paper describes the data processing software, the EUVE survey data set, and the production of the BSL at the Center for EUV Astrophysics. The contents, format, and selection criteria for sources, the data processing strategy, some problems encountered, and a summary of the BSL results are presented.

  1. All things bright and beautiful

    OpenAIRE

    Brown, Chloe

    2012-01-01

    'All Things Bright and Beautiful' was exhibited in 20/21 Visual Arts Centre, Scunthorpe, which is sited in a 'redundant' church. The fundamental question that the exhibition explored concerned the role of 'the animal' within contemporary art and within secular society, which in turn hoped to prompt reflections on our understanding of the place of 'the human' in the world and in nature. If there is no divine order, as posited by the hymn 'All Things Bright and Beautiful', where does this leave...

  2. Bright Transients discovered by PSST

    Science.gov (United States)

    Smith, K. W.; Wright, D.; Smartt, S. J.; Huber, M.; Chambers, K. C.; Flewelling, H.; Willman, M.; Primak, N.; Schultz, A.; Gibson, B.; Magnier, E.; Waters, C.; Tonry, J.; Wainscoat, R. J.; Denneau, L.; Stalder, B.; Heinze, A.; Sherstyuk, A.; Foley, R. J.; Jha, S. W.; Rest, A.; Scolnic, D.

    2016-04-01

    Seven bright transients have been discovered as part of the Pan-STARRS Survey for Transients (PSST). Information on all objects discovered by the Pan-STARRS Survey for Transients is available at http://star.pst.qub.ac.uk/ps1threepi/ (see Huber et al. ATel #7153).

  3. Bright Transients discovered by PSST

    Science.gov (United States)

    Smith, K. W.; Wright, D.; Smartt, S. J.; Young, D. R.; Huber, M.; Chambers, K. C.; Flewelling, H.; Willman, M.; Primak, N.; Schultz, A.; Gibson, B.; Magnier, E.; Waters, C.; Tonry, J.; Wainscoat, R. J.; Foley, R. J.; Jha, S. W.; Rest, A.; Scolnic, D.

    2016-08-01

    Six bright transients have been discovered as part of the Pan-STARRS Survey for Transients (PSST). Information on all objects discovered by the Pan-STARRS Survey for Transients is available at http://star.pst.qub.ac.uk/ps1threepi/ (see Huber et al. ATel #7153).

  4. Molecular basis of photochromism of a fluorescent protein revealed by direct 13C detection under laser illumination

    International Nuclear Information System (INIS)

    Dronpa is a green fluorescent protein homologue with a photochromic property. A green laser illumination reversibly converts Dronpa from a green-emissive bright state to a non-emissive dark state, and ultraviolet illumination converts it to the bright state. We have employed solution NMR to understand the underlying molecular mechanism of the photochromism. The detail characterization of Dronpa is hindered as it is metastable in the dark state and spontaneously converts to the bright state. To circumvent this issue, we have designed in magnet laser illumination device. By combining the device with a 150-mW argon laser at 514.5 nm, we have successfully converted and maintained Dronpa in the dark state in the NMR tube by continuous illumination during the NMR experiments. We have employed direct-detection of 13C nuclei from the carbon skeleton of the chromophore for detailed characterization of chromophore in both states of Dronpa by using the Bruker TCI cryoprobe. The results from NMR data have provided direct evidence of the double bond formation between Cα and Cβ of Y63 in the chromophore, the β-barrel structure in solution, and the ionized and protonated state of Y63 hydroxyl group in the bright and dark states, respectively. These studies have also revealed that a part of β-barrel around the chromophore becomes polymorphic only in the dark state, which may be critical to make the fluorescence dim by increasing the contribution of non-emissive vibrational relaxation pathways.

  5. Response of carbon assimilation and chlorophyll fluorescence to soybean leaf phosphorus across CO2: Alternative electron sink, nutrient efficiency and critical concentration.

    Science.gov (United States)

    Singh, Shardendu K; Reddy, Vangimalla R

    2015-10-01

    To evaluate the response of CO2 assimilation rate (PN) and various chlorophyll fluorescence (CF) parameters to phosphorus (P) nutrition, soybean plants were grown in controlled environment with sufficient (0.50mM) and deficient (0.10 and 0.01 mM) phosphate (P) supply under ambient and elevated CO2 (aCO2, 400 and eCO2, 800 μmol mol(-1), respectively). Measurements were made at ambient (21%) and low (2%) O2 concentrations. Results showed strong correlation of leaf P concentration with PN and CF parameters. The P deficiency showed parallel decreases in PN, and CF parameters including quantum efficiency (Fv'/Fm'), quantum yield of photosystem II (ΦPSII), electron transport rate (JF), and photochemical quenching (qP). The Fv'/Fm' decreased as a result of greater decline in maximal (Fm') than minimal (Fo') fluorescence. The eCO2 stimulated PN especially under higher leaf P concentrations. Low O2 also stimulated PN but only at aCO2. The photosynthetic carbon reduction (PCR, signified by PN) and photorespiratory carbon oxidation cycles (PCO, signified photorespiration as indicated by ratio of JF to gross PN and % increase in PN at 2% O2) was the major electron sinks. However, the presence of alternative electron sink was also evident as determined by the difference between the electron transport calculated from chlorophyll fluorescence and gas exchange measurements. Alternative electron sink declined at lower leaf P concentration suggesting its minor role in photochemical energy consumption, thus dissipation of the excess excitation pressure of PSII reaction center under P deficiency. The JF/PG and % increase in PN at 2 versus 21% O2 remained consistent across leaf P concentration suggesting PCO cycle as an important mechanism to dissipate excess excitation energy in P deficient leaves. The severe decline of Fv'/Fm', ΦPSII, JF and qP under P deficiency also suggested the occurrences of excess radiant energy dissipation by non-photochemical quenching mechanisms. Critical

  6. Fluorescence uranium determination

    International Nuclear Information System (INIS)

    An equipment for analysis of uranium by fluorescence was developed in order to determine it at such a low concentration that it can not be determined by the most sensible analytical methods. this new fluorimeter was adapted to measure the fluorescence emitted by the phosphorus sodium fluoride-sodium carbonate-potasium carbonate-uranyl, being excited by ultraviolet light of 3,650 A the intensity of the light emitted was measure with a photomultiplicator RCA 5819 and the adequate electronic equipment. (Author) 19 refs

  7. Fluorescent Approaches to High Throughput Crystallography

    Science.gov (United States)

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

    2006-01-01

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

  8. A new fluorescent nitrogen-doped carbon dot system modified by the fluorophore-labeled ssDNA for the analysis of 6-mercaptopurine and Hg (II).

    Science.gov (United States)

    Li, Zhuo; Ni, Yongnian; Kokot, Serge

    2015-12-15

    A simple, environmentally friendly hydrothermal method was used to prepare strongly luminescent, nitrogen-doped carbon dots (NCDs) with the use of Chinese yams as a source of carbon and nitrogen. Such NCDs have an average size of 2.7±1.4 nm; they emit blue light at 420 nm and have a quantum yield of up to 9.3%. Thus, carboxyfluorescein (FAM)-DNA macro-molecules were assembled on the surfaces of the NCDs, and stabilised by strong π-π stacking; the so formed hybrid nano-sensors were found to have an ultra-sensitive response to 6-mercaptopurine (6-MP). A strong emission and enhancement of yellow radiation was observed from FAM. Furthermore, due to the specific interactions between DNA and Hg(2+), which resulted in the formation of the T-Hg(2+)-T (T: thymine base) complex - a large, conjugated system, which formed between NCDs, DNA and 6-MP, was broken up. Thus, the fluorescence from FAM was quenched. The detection limits for 6-MP and Hg(2+) were 0.67 and 1.26 nM, respectively. The proposed method was applied for the determination of 6-MP in human serum and Hg(2+) in water samples with satisfactory results. PMID:26120815

  9. Facile preparation of Gd3+ doped carbon quantum dots: Photoluminescence materials with magnetic resonance response as magnetic resonance/fluorescence bimodal probes

    Science.gov (United States)

    Ren, X. Y.; Yuan, X. X.; Wang, Y. P.; Liu, C. L.; Qin, Y.; Guo, L. P.; Liu, L. H.

    2016-07-01

    There are a few bimodal molecular imaging probes constructed by gadolinium (3+) ions in combination with carbon quantum dots (CQDs), and the reported ones show such obvious drawbacks as low luminous efficiency and weak MRI contrast. In the paper, a kind of CQDs photoluminescence materials with magnetic resonance response was prepared by hydrothermal method and employing gadopentetate monomeglumine (GdPM) as a precusor. Here, the GdPM plays a role of not only carbon source, but also gadolinium (3+) sources. When the GdPM aqueous solution with a concentration of 4 mg mL-1 was pyrolyzed under 220 °C and 2.0 MPa for 8 h, an optimal CQDs was obtained which are doped with gadolinium (3+) ions in both chelates and Gd2O3 (named as Gd3+-CQDs). The average diameter of the Gd3+-CQDs is about 1.6 nm, which show a high photoluminescence quantum yield of 7.1%, as well as high longitudinal relaxivity (r1) of 9.87 mM-1 s-1. And owing to the unconspicuous cell toxicity, the Gd3+-CQDs show big possibility for clinical application in magnetic resonance/fluorescence bimodal molecular imaging.

  10. A fluorescent graphitic carbon nitride nanosheet biosensor for highly sensitive, label-free detection of alkaline phosphatase

    Science.gov (United States)

    Xiang, Mei-Hao; Liu, Jin-Wen; Li, Na; Tang, Hao; Yu, Ru-Qin; Jiang, Jian-Hui

    2016-02-01

    Graphitic C3N4 (g-C3N4) nanosheets provide an attractive option for bioprobes and bioimaging applications. Utilizing highly fluorescent and water-dispersible ultrathin g-C3N4 nanosheets, a highly sensitive, selective and label-free biosensor has been developed for ALP detection for the first time. The developed approach utilizes a natural substrate of ALP in biological systems and thus affords very high catalytic efficiency. This novel biosensor is demonstrated to enable quantitative analysis of ALP in a wide range from 0.1 to 1000 U L-1 with a low detection limit of 0.08 U L-1, which is among the most sensitive assays for ALP. It is expected that the developed method may provide a low-cost, convenient, rapid and highly sensitive platform for ALP-based clinical diagnostics and biomedical applications.Graphitic C3N4 (g-C3N4) nanosheets provide an attractive option for bioprobes and bioimaging applications. Utilizing highly fluorescent and water-dispersible ultrathin g-C3N4 nanosheets, a highly sensitive, selective and label-free biosensor has been developed for ALP detection for the first time. The developed approach utilizes a natural substrate of ALP in biological systems and thus affords very high catalytic efficiency. This novel biosensor is demonstrated to enable quantitative analysis of ALP in a wide range from 0.1 to 1000 U L-1 with a low detection limit of 0.08 U L-1, which is among the most sensitive assays for ALP. It is expected that the developed method may provide a low-cost, convenient, rapid and highly sensitive platform for ALP-based clinical diagnostics and biomedical applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08278a

  11. Helmholtz bright and boundary solitons

    International Nuclear Information System (INIS)

    We report, for the first time, exact analytical boundary solitons of a generalized cubic-quintic nonlinear Helmholtz (NLH) equation. These solutions have a linked-plateau topology that is distinct from conventional dark soliton solutions; their amplitude and intensity distributions are spatially delocalized and connect regions of finite and zero wave-field disturbances (suggesting also the classification as 'edge solitons'). Extensive numerical simulations compare the stability properties of recently derived Helmholtz bright solitons, for this type of polynomial nonlinearity, to those of the new boundary solitons. The latter are found to possess a remarkable stability characteristic, exhibiting robustness against perturbations that would otherwise lead to the destabilizing of their bright-soliton counterparts

  12. Helmholtz bright and boundary solitons

    Energy Technology Data Exchange (ETDEWEB)

    Christian, J M [Joule Physics Laboratory, School of Computing, Science and Engineering, Institute for Materials Research, University of Salford, Salford M5 4WT (United Kingdom); McDonald, G S [Joule Physics Laboratory, School of Computing, Science and Engineering, Institute for Materials Research, University of Salford, Salford M5 4WT (United Kingdom); Chamorro-Posada, P [Departmento de TeorIa de la Senal y Comunicaciones e IngenierIa Telematica, Universidad de Valladolid, ETSI Telecomunicacion, Campus Miguel Delibes s/n, 47011 Valladolid (Spain)

    2007-02-16

    We report, for the first time, exact analytical boundary solitons of a generalized cubic-quintic nonlinear Helmholtz (NLH) equation. These solutions have a linked-plateau topology that is distinct from conventional dark soliton solutions; their amplitude and intensity distributions are spatially delocalized and connect regions of finite and zero wave-field disturbances (suggesting also the classification as 'edge solitons'). Extensive numerical simulations compare the stability properties of recently derived Helmholtz bright solitons, for this type of polynomial nonlinearity, to those of the new boundary solitons. The latter are found to possess a remarkable stability characteristic, exhibiting robustness against perturbations that would otherwise lead to the destabilizing of their bright-soliton counterparts.

  13. Bright solitons from defocusing nonlinearities

    OpenAIRE

    Borovkova, Olga V.; Kartashov, Yaroslav; Torner Sabata, Lluís; Malomed, Boris A.

    2011-01-01

    We report that defocusing cubic media with spatially inhomogeneous nonlinearity, whose strength increases rapidly enough toward the periphery, can support stable bright localized modes. Such nonlinearity landscapes give rise to a variety of stable solitons in all three dimensions, including one-dimensional fundamental and multihump states, two-dimensional vortex solitons with arbitrarily high topological charges, and fundamental solitons in three dimensions. Solitons maintain their coherence ...

  14. Scintillation camera brightness calibration apparatus

    International Nuclear Information System (INIS)

    Circuitry is described for calibrating the brightness of a cathode ray tube display and recording apparatus comprising: 1) intensity control means for adjusting the intensity of the cathode ray tube beam; 2) light sensitive means disposed to receive light emitted from the cathode ray tube and generating a first electrical signal having a magnitude dependent upon the intensity of the emitted light; 3) reference signal generating means for generating a second electrical signal of predetermined magnitude; and 4) electrical signal comparison means coupled to the light sensitive means and the reference signal generating means for comparing the magnitude of the first and second electrical signals. (author)

  15. High-brightness electron injectors

    International Nuclear Information System (INIS)

    Free-electron laser (FEL) oscillators and synchrotron light sources require pulse trains of high peak brightness and, in some applications, high-average power. Recent developments in the technology of photoemissive and thermionic electron sources in rf cavities for electron-linac injector applications offer promising advances over conventional electron injectors. Reduced emittance growth in high peak-current electron injectors may be achieved by using high field strengths and by linearizing the radial component of the cavity electric field at the expense of lower shunt impedance

  16. High brightness beams and applications

    International Nuclear Information System (INIS)

    This paper describes the present research on attaining intense bright electron beams. Thermionic systems are briefly covered. Recent and past results from the photoinjector programs are given. The performance advantages and difficulties presently faced by researchers using photoinjectors is discussed. The progress that has been made in photocathode materials, both in lifetime and quantum efficiency, is covered. Finally, a discussion of emittance measurements of photoinjector systems and how the measurement is complicated by the non-thermal nature of the electron beam is presented

  17. Fabrication and imaging study of ultrasound/fluorescence bi-modal contrast agent based on polymeric microbubbles

    International Nuclear Information System (INIS)

    Objective: To fabricate an ultrasound/fluorescence bi-modal contrast agent by encapsulating fluorescent quantum dots into polymeric ultrasound contrast agent microbubbles. Methods: Polylactic acid (PLA, 500 mg), (1R)-(+)-camphor (50 mg) and CdSe/ZnS quantum dots (0.5 ml, 2.3 μmol/L)were dissolved or dispersed in dichloromethane (10 ml) to form in an organic phase. Ammonium carbonate solution and poly (vinyl alcohol) solution were employed as the internal and external water phase, respectively. The fluorescent microbubbles were generated using double emulsion solvent evaporation and lyophilization methods. The morphology and illumination were characterized by scanning electron microscopy (SEM) and fluorescence spectrophotometry. Synchronized contrast-enhanced ultrasound and fluorescence imaging was acquired by injecting fluorescent microbubbles into the silicone tube coupled to a self-made ultrasound/fluorescence imaging device. Ultrasound/fluorescence bi-modal in vivo imaging was acquired on the kidney of New Zealand rabbits and suckling mice. Results: The fluorescent microbubbles were hollow spheres with an averaged diameter of (1.62 ± 1.47) μm. More than 99% of these microbubbles were less than 8 μm in diameter, which met the size criteria for ultrasound contrast agents. The fluorescence emission peak of the microbubbles appeared at 632 nm, indicating that good luminescence properties of quantum dots were maintained. In vitro ultrasound/fluorescence imaging showed no echoic signal when the silicone tube was filled with saline, but there was a strong echo when filled with fluorescent microbubbles. The liquid column with fluorescent microbubbles emitted red luminescence under ultraviolet irradiation. The kidney of the rabbit was remarkably enhanced after the administration of fluorescent microbubbles. Bright fluorescence could be observed at the injection site of the suckling mice via subcutaneous injection. Conclusions: A bi-modal but single contrast agent

  18. Temporal and spatial changes in dissolved organic carbon concentration and fluorescence intensity of fulvic acid like materials in mountainous headwater catchments

    Science.gov (United States)

    Terajima, Tomomi; Moriizumi, Mihoko

    2013-02-01

    SummaryDissolved organic carbon (DOC) such as humic substances are key to understanding the aquatic environment in catchments, because they, containing a large number of phenolic and carboxylic acid groups, adsorb many kinds of inorganic materials and also affect nutrition and carbon transport in catchments. To understand the detailed DOC dynamics, we conducted hydrological observations at mountainous headwater catchments dominated by different vegetation types (planted evergreen coniferous forest of 1.29 ha and natural deciduous broadleaf forest of 1.28 ha). The relationship between DOC concentrations and fluorescence intensity of fulvic acid-like materials (F-FAM) were positively correlated in both catchments but different between soil extracts, baseflow, and near surface flow represented by biomat flow. The ratios of change in F-FAM to that in DOC concentration (F-FAM/DOC) were higher in the baseflow (about 6 in both catchments) and lower in the soil extracts (about 4.5 in both catchments, respectively). However, the relationship in stormflow was distributed between the trends of baseflow and soil extracts. The higher F-FAM/DOC in baseflow may thus indicate that DOC (and FAM) in groundwater discharge mainly contributed to the stream flow, and the stormflow mainly reflect subsurface flow through soil during most rainstorms. In contrast, a high F-FAM/DOC ratio (>6) appeared in the stormflow of both catchments especially during large storms of short duration and high intensity following a dry antecedent period. The F-FAM/DOC in biomat flow developing distinctly in the coniferous catchment was high (about 6.5). Thus, rapid shallow subsurface flow through the biomat or near-surface of slopes might explain the unique transport dynamics of DOC and FAM in stormflows with the high F-FAM/DOC ratio. These results imply that the DOC and FAM relationship responds variably depending on both the distribution of soil organic matter and rainwater flow paths in steep slopes as

  19. In vivo fluorescence imaging in the second near-infrared window with long circulating carbon nanotubes capable of ultrahigh tumor uptake.

    Science.gov (United States)

    Robinson, Joshua T; Hong, Guosong; Liang, Yongye; Zhang, Bo; Yaghi, Omar K; Dai, Hongjie

    2012-06-27

    Cancer imaging requires selective high accumulation of contrast agents in the tumor region and correspondingly low uptake in healthy tissues. Here, by making use of a novel synthetic polymer to solubilize single-walled carbon nanotubes (SWNTs), we prepared a well-functionalized SWNT formulation with long blood circulation (half-life of ∼30 h) in vivo to achieve ultrahigh accumulation of ∼30% injected dose (ID)/g in 4T1 murine breast tumors in Balb/c mice. Functionalization dependent blood circulation and tumor uptake were investigated through comparisons with phospholipid-PEG solubilized SWNTs. For the first time, we performed video-rate imaging of tumors based on the intrinsic fluorescence of SWNTs in the second near-infrared (NIR-II, 1.1-1.4 μm) window. We carried out dynamic contrast imaging through principal component analysis (PCA) to immediately pinpoint the tumor within ∼20 s after injection. Imaging over time revealed increasing tumor contrast up to 72 h after injection, allowing for its unambiguous identification. The 3D reconstruction of the SWNTs distribution based on their stable photoluminescence inside the tumor revealed a high degree of colocalization of SWNTs and blood vessels, suggesting enhanced permeability and retention (EPR) effect as the main cause of high passive tumor uptake of the nanotubes. PMID:22667448

  20. Carbon dots with strong excitation-dependent fluorescence changes towards pH. Application as nanosensors for a broad range of pH.

    Science.gov (United States)

    Barati, Ali; Shamsipur, Mojtaba; Abdollahi, Hamid

    2016-08-10

    In this study, preparation of novel pH-sensitive N-doped carbon dots (NCDs) using glucose and urea is reported. The prepared NCDs present strong excitation-dependent fluorescence changes towards the pH that is a new behavior from these nanomaterials. By taking advantage of this unique behavior, two separated ratiometric pH sensors using emission spectra of the NCDs for both acidic (pH 2.0 to 8.0) and basic (pH 7.0 to 14.0) ranges of pH are constructed. Additionally, by considering the entire Excitation-Emission Matrix (EEM) of NCDs as analytical signal and using a suitable multivariate calibration method, a broad range of pH from 2.0 to 14.0 was well calibrated. The multivariate calibration method was independent from the concentration of NCDs and resulted in a very low average prediction error of 0.067 pH units. No changes in the predicted pH under UV irradiation (for 3 h) and at high ionic strength (up to 2 M NaCl) indicated the high stability of this pH nanosensor. The practicality of this pH nanosensor for pH determination in real water samples was validated with good accuracy and repeatability. PMID:27282748

  1. The fluorescent bioprobe with aggregation-induced emission features for monitoring to carbon dioxide generation rate in single living cell and early identification of cancer cells.

    Science.gov (United States)

    Chen, Didi; Wang, Huan; Dong, Lichao; Liu, Pai; Zhang, Yahui; Shi, Jianbing; Feng, Xiao; Zhi, Junge; Tong, Bin; Dong, Yuping

    2016-10-01

    A novel fluorescent probe, tris (2-(dimethylamino) ethyl)-4,4',4″-(1H-pyrrole-1,2,5-triyl) tribenzoate (TPP-TMAE), with aggregation-enhanced emission (AEE) feature showed a simple, highly selective, specific, and instant response to trace amount carbon dioxide (CO2). Because of this special characteristic, TPP-TMAE is ideal to be a biomarker for in-situ monitoring of the CO2 generation rate during the metabolism of single living cell. The rates in single living HeLa cell, MCF-7 cell, and MEF cell were 6.40 × 10(-6)±6.0 × 10(-8) μg/h, 5.78 × 10(-6)±6.0 × 10(-8) μg/h, and 4.27 × 10(-7)±4.0 × 10(-9) μg/h, respectively. The distinct responses of TPP-TMAE to CO2 generated from cancer cells and normal cells suggested TPP-TMAE as a useful tool for deeper understanding metabolism process and distinguishing cancer cells from normal cells during the early diagnosis of cancers. PMID:27372422

  2. A Novel Technique of Synthesis of Highly Fluorescent Carbon Nanoparticles from Broth Constituent and In-vivo Bioimaging of C. elegans.

    Science.gov (United States)

    Pramanik, A; Kole, A K; Krishnaraj, R N; Biswas, S; Tiwary, C S; Varalakshmi, P; Rai, S K; Kumar, B A; Kumbhakar, P

    2016-09-01

    Here we have demonstrated a novel single step technique of synthesis of highly fluorescent carbon nanoparticles (CNPs) from broth constituent and in vivo bioimaging of Caenorhabditis elegans (C. elegans) with the synthesized CNPs has been presented. The synthesized CNPs has been characterized by the UV-visible (UV-Vis) absorption spectroscopy, transmission electron microscopy (TEM) and Raman studies. The sp (2) cluster size of the synthesized samples has been determined from the measured Raman spectra by fitting it with the theoretical skew Lorentzian (Breit-Wigner- Fano (BWF)) line shape. The synthesised materials are showing excitation wavelength dependent tunable photoluminescence (PL) emission characteristics with a high quantum yield (QY) of 3 % at a very low concentration of CNPs. A remarkable increase in the intensity of PL emission from 16 % to 39 % in C. elegans has also been observed when the feeding concentration of CNPs to C. elegans is increased from 0.025 % to 0.1 % (w/v). The non-toxicity and water solubility of the synthesized material makes it ideal candidate for bioimaging. PMID:27380200

  3. Carbon-Nitrogen-Oxygen Line Radiation and the X-ray Bowen Fluorescence Mechanism in Optically Thick, Highly Ionized Media

    Science.gov (United States)

    Sako, Masao

    2003-01-01

    Radiative transfer effects due to overlapping X-ray lines in a high-temperature, optically thick, highly ionized medium are investigated. One particular example, in which the O VIII Lyalpha doublet (2(sup 2) P(sub 1/2,3/2)-1(sup 2) S(sub 1/2) coincides in frequency with the N VII Lyzeta lines (7(sup 2) P(sub 1/2,3/2)-1(sup 2) S(sub 1/2) is studied in detail to illustrate the effects on the properties of the emergent line spectrum. We solve the radiative transfer equation to study the energy transport of resonance-line radiation in a static, infinite, plane-parallel geometry, which is used to compute the destruction/escape probabilities for each of the lines for various total optical thicknesses of the medium, as well as destruction probabilities by sources of underlying photoelectric opacity. It is found that a large fraction of the O vIII Lyalpha line radiation can be destroyed by N VII, which can result in a reversal of the O VIII Lyalpha/N VII Lyalpha line intensity ratio similar to what may be seen under nonsolar abundances. Photoelectric absorption by ionized carbon and nitrogen can also subsequently increase the emission-line intensities of these ions. We show that line ratios, which are directly proportional to the abundance ratios in optically thin plasmas, are not good indicators of the true CNO abundances. Conversely, global spectral modeling that assumes optically thin conditions may yield incorrect abundance estimates when compared with observations, especially if the optical depth is large. Other potentially important overlapping lines and continua in the X-ray band are also identified, and their possible relevance to recent high-resolution spectroscopic observations with Chandra and XMM-Newton are briefly discussed.

  4. How Bright Can Supernovae Get?

    Science.gov (United States)

    Kohler, Susanna

    2016-04-01

    Supernovae enormous explosions associated with the end of a stars life come in a variety of types with different origins. A new study has examined how the brightest supernovae in the Universe are produced, and what limits might be set on their brightness.Ultra-Luminous ObservationsRecent observations have revealed many ultra-luminous supernovae, which haveenergies that challenge our abilities to explain them usingcurrent supernova models. An especially extreme example is the 2015 discovery of the supernova ASASSN-15lh, which shone with a peak luminosity of ~2*1045 erg/s, nearly a trillion times brighter than the Sun. ASASSN-15lh radiated a whopping ~2*1052 erg in the first four months after its detection.How could a supernova that bright be produced? To explore the answer to that question, Tuguldur Sukhbold and Stan Woosley at University of California, Santa Cruz, have examined the different sources that could produce supernovae and calculated upper limits on the potential luminosities ofeach of these supernova varieties.Explosive ModelsSukhbold and Woosley explore multiple different models for core-collapse supernova explosions, including:Prompt explosionA stars core collapses and immediately explodes.Pair instabilityElectron/positron pair production at a massive stars center leads to core collapse. For high masses, radioactivity can contribute to delayed energy output.Colliding shellsPreviously expelled shells of material around a star collide after the initial explosion, providing additional energy release.MagnetarThe collapsing star forms a magnetar a rapidly rotating neutron star with an incredibly strong magnetic field at its core, which then dumps energy into the supernova ejecta, further brightening the explosion.They then apply these models to different types of stars.Setting the LimitThe authors show that the light curve of ASASSN-15lh (plotted in orange) can be described by a model (black curve) in which a magnetar with an initial spin period of 0.7 ms

  5. VERITAS Observations under Bright Moonlight

    CERN Document Server

    ,

    2015-01-01

    The presence of moonlight is usually a limiting factor for imaging atmospheric Cherenkov telescopes due to the high sensitivity of the camera photomultiplier tubes (PMTs). In their standard configuration, the extra noise limits the sensitivity of the experiment to gamma-ray signals and the higher PMT currents also accelerates PMT aging. Since fall 2012, observations have been carried out with VERITAS under bright moonlight (Moon illumination $> 35\\%$), in two observing modes, by reducing the voltage applied to the PMTs and with UV bandpass filters, which allow observations up to $\\sim80\\%$ Moon illumination resulting in $29\\%$ more observing time over the course of the year. In this presentation, we provide details of these new observing modes and their performance relative to the standard VERITAS observations.

  6. [Bright light therapy for elderly].

    Science.gov (United States)

    Okawa, Masako

    2015-06-01

    Bright light therapy (BLT) holds considerable promise for sleep problems in the elderly. BLT for community-dwelling patients with Alzheimer's disease showed significant improvement in sleep parameters. In the institutional setting, BLT was effective in reducing daytime nap duration. Morning BLT was found to advance the peak circadian rhythm and increase activity level in daytime and melatonin level at night. Light therapy could be used in combination with other nonpharmacological methods such as social activities, outside walking, physical exercises, which showed greater effects than independent BLT on sleep and cognitive function. BLT treatment strategy was proposed in the present paper. We should pay more attentions to BLT in community setting for mental and physical well-being. PMID:26065132

  7. The lowest surface brightness disc galaxy known

    International Nuclear Information System (INIS)

    The discovery of a galaxy with a prominent bulge and a dominant extremely low surface brightness disc component is reported. The profile of this galaxy is very similar to the recently discovered giant low surface brightness galaxy Malin 1. The disc central surface brightness is found to be ∼ 26.4 Rμ, some 1.5 mag fainter than Malin 1 and thus by far the lowest yet observed. (author)

  8. J Fluorescence

    OpenAIRE

    Resch-Genger, U.; Hoffmann, K.; Nietfeld, W; A. Engel; Neukammer, J.; Nitschke, R.; Ebert, P.; Macdonald, R

    2005-01-01

    The scope of this paper is to illustrate the need for an improved quality assurance in fluorometry. For this purpose, instrumental sources of error and their influences on the reliability and comparability of fluorescence data are highlighted for frequently used photoluminescence techniques ranging from conventional macro- and microfluorometry over fluorescence microscopy and flow cytometry to microarray technology as well as in vivo fluorescence imaging. Particularly, the need for and requir...

  9. Quantum communication with macroscopically bright nonclassical states.

    Science.gov (United States)

    Usenko, Vladyslav C; Ruppert, Laszlo; Filip, Radim

    2015-11-30

    We analyze homodyne detection of macroscopically bright multimode nonclassical states of light and propose their application in quantum communication. We observe that the homodyne detection is sensitive to a mode-matching of the bright light to the highly intense local oscillator. Unmatched bright modes of light result in additional noise which technically limits detection of Gaussian entanglement at macroscopic level. When the mode-matching is sufficient, we show that multimode quantum key distribution with bright beams is feasible. It finally merges the quantum communication with classical optical technology of visible beams of light. PMID:26698776

  10. Preparation of Fluorescent Carbon Nanoparticles by Glow Discharge Plasma at Atmospheric Pressure%常压辉光放电等离子体制备荧光碳纳米粒子

    Institute of Scientific and Technical Information of China (English)

    谢春香; 张禹涛; 马腾才

    2012-01-01

    Superfine fluorescent carbon nanoparticles were prepared by glow discharge plasma,which generated a large amout of active particles such as high-energy electrons to decompose ethanol,and then to initiate the free radical reactions for producing the carbon nanoparticles.Either polyethylene glycol(PEG) 2000 or polyvinylpyrrolidone(PVP) 20000 was used as surfactant or surface modifier for the ethanol.The fluorescent properties and morphology of the carbon nanoparticles were characterized by fluorescence spectrophotometer and transmission electron microscopy(TEM),respectively.The results show that the morphology of fluorescent carbon nanoparticles is graphitic.The fluorescent intensities of the nanoparticles increase with reaction time,and they are higher in the resultants modified by PEG-2000 than by PVP-20000,as well as for those generated under streamer discharge mode than under glow discharge one.The quantum yield of photoluminescence is 46.58% for carbon nanoparticles prepared.%采用常压辉光放电等离子体制备了超细荧光碳纳米粒子。分别采用聚乙二醇(PEG)2000和聚乙烯吡咯烷酮(PVP)20000作为表面活性剂和表面修饰剂,利用辉光放电等离子体射流产生的大量高能电子等活性粒子分解乙醇溶液制备碳纳米粒子。采用透射电子显微镜和荧光分光光度计对生成物的形貌和荧光特性进行了检测。结果表明,生成物为石墨相的荧光碳纳米颗粒。随着反应时间的延长,生成物的荧光强度增强;采用PEG-2000修饰后产物的荧光强度比采用PVP-20000更强;丝状放电模式下生成物的荧光强度高于辉光放电模式。制备的碳纳米颗粒的荧光量子产率为46.58%。

  11. Soliton fay identities: II. Bright soliton case

    International Nuclear Information System (INIS)

    We present a set of bilinear matrix identities that generalize the ones that have been used to construct the bright soliton solutions for various models. As an example of an application of these identities, we present a simple derivation of the N-bright soliton solutions for the Ablowitz–Ladik hierarchy. (paper)

  12. Incoherently coupled dark-bright photorefractive solitons

    Science.gov (United States)

    Chen, Zhigang; Segev, Mordechai; Coskun, Tamer H.; Christodoulides, Demetrios N.; Kivshar, Yuri S.; Afanasjev, Vsevolod V.

    1996-11-01

    We report the observation of incoherently coupled dark-bright spatial soliton pairs in a biased bulk photorefractive crystal. When such a pair is decoupled, the dark component evolves into a triplet structure, whereas the bright one decays into a self-defocusing beam.

  13. Spatial Brightness Perception of Trichromatic Stimuli

    Energy Technology Data Exchange (ETDEWEB)

    Royer, Michael P.; Houser, Kevin W.

    2012-11-16

    An experiment was conducted to examine the effect of tuning optical radiation on brightness perception for younger (18-25 years of age) and older (50 years of age or older) observers. Participants made forced-choice evaluations of the brightness of a full factorial of stimulus pairs selected from two groups of four metameric stimuli. The large-field stimuli were created by systematically varying either the red or the blue primary of an RGB LED mixture. The results indicate that light stimuli of equal illuminance and chromaticity do not appear equally bright to either younger or older subjects. The rank-order of brightness is not predicted by any current model of human vision or theory of brightness perception including Scotopic to Photopic or Cirtopic to Photopic ratio theory, prime color theory, correlated color temperature, V(λ)-based photometry, color quality metrics, linear brightness models, or color appearance models. Age may affect brightness perception when short-wavelength primaries are used, especially those with a peak wavelength shorter than 450 nm. The results suggest further development of metrics to predict brightness perception is warranted, and that including age as a variable in predictive models may be valuable.

  14. Soliton Fay identities. II. Bright soliton case

    OpenAIRE

    Vekslerchik, V. E.

    2015-01-01

    We present a set of bilinear matrix identities that generalize the ones that have been used to construct the bright soliton solutions for various models. As an example of an application of these identities, we present a simple derivation of the N-bright soliton solutions for the Ablowitz-Ladik hierarchy.

  15. Galaxy selection and the surface brightness distribution

    CERN Document Server

    McGaugh, S S; Schombert, J M

    1995-01-01

    Optical surveys for galaxies are biased against the inclusion of low surface brightness (LSB) galaxies. Disney (1976) suggested that the constancy of disk central surface brightness noticed by Freeman (1970) was not a physical result, but instead was an artifact of sample selection. Since LSB galaxies do exist, the pertinent and still controversial issue is if these newly discovered galaxies constitute a significant percentage of the general galaxy population. In this paper, we address this issue by determining the space density of galaxies as a function of disk central surface brightness. Using the physically reasonable assumption (which is motivated by the data) that central surface brightness is independent of disk scale length, we arrive at a distribution which is roughly flat (\\ie approximately equal numbers of galaxies at each surface brightness) faintwards of the Freeman (1970) value. Brightwards of this, we find a sharp decline in the distribution which is analogous to the turn down in the luminosity ...

  16. Preparation of Fluorescent Carbon Dots and Its Cytotoxicity for Saccharomyce cerevisiae%荧光碳点的合成及对酿酒酵母的毒性研究

    Institute of Scientific and Technical Information of China (English)

    黄淮青; 曾萍; 韩宝福; 徐淑坤

    2012-01-01

    以葡萄糖为碳源采用溶剂热法合成了荧光碳点.紫外吸收光谱、荧光光谱以及透射电镜照片表明,所合成的荧光碳点发光性能优异,分散性好,且无团聚现象.荧光碳点原溶液出现浓度淬灭现象,稀释60倍情况下荧光最强.以酿酒酵母为模型生物,考察了不同生长时期(调整期、对数期早期、对数期中期)的酿酒酵母与不同浓度的荧光碳点共培养后的生长曲线.结果表明,即使荧光碳点浓度在27.75 mmol·L-1条件下也没有影响酵母菌的生长曲线,可认为基本没有细胞毒性.比较了相同荧光强度下的荧光碳点与CdTe量子点对酿酒酵母的细胞毒性,结果表明荧光碳点的毒性显著低于量子点的毒性.%Fluorescent carbon dots (CDs) were synthesized by a solvothermal method with glucose as the carbon source. UV absorption and fluorescence spectroscopy, and transmission electron microscopy (TEM) results showed that the synthesized CDs feature the excellent optical performance and high dispersion without agglomeration. The as-prepared CDs solution displayed a concentration quenching phenomenon and emitted the strongest fluorescence after being diluted 60 times. By using Saccharomyce cerevisiae yeast as a model organism, we investigated the dependence of yeast's growth on the concentration of fluorescent CDs at various growth periods (adjustment, initial and middle logarithmic phases). It is shown that there is no influence on yeast's growth curve even the concentration of fluorescent CDs as high as 27.75 mmol·L-1. The yeast cytotoxicity of fluorescent CDs and CdTe quantum dots were also compared under the same fluorescent intensity, indicating a much lower cytotoxicity fluorescent of CDs than that CdTe quantum dots.

  17. Bright, NIR-emitting Au23 from Au25: characterization and applications including biolabeling.

    Science.gov (United States)

    Muhammed, Madathumpady Abubaker Habeeb; Verma, Pramod Kumar; Pal, Samir Kumar; Kumar, R C Arun; Paul, Soumya; Omkumar, Ramakrishnapillai Vyomakesannair; Pradeep, Thalappil

    2009-10-01

    A novel interfacial route has been developed for the synthesis of a bright-red-emitting new subnanocluster, Au(23), by the core etching of a widely explored and more stable cluster, Au(25)SG(18) (in which SG is glutathione thiolate). A slight modification of this procedure results in the formation of two other known subnanoclusters, Au(22) and Au(33). Whereas Au(22) and Au(23) are water soluble and brightly fluorescent with quantum yields of 2.5 and 1.3 %, respectively, Au(33) is organic soluble and less fluorescent, with a quantum yield of 0.1 %. Au(23) exhibits quenching of fluorescence selectively in the presence of Cu(2+) ions and it can therefore be used as a metal-ion sensor. Aqueous- to organic-phase transfer of Au(23) has been carried out with fluorescence enhancement. Solvent dependency on the fluorescence of Au(23) before and after phase transfer has been studied extensively and the quantum yield of the cluster varies with the solvent used. The temperature response of Au(23) emission has been demonstrated. The inherent fluorescence of Au(23) was used for imaging human hepatoma cells by employing the avidin-biotin interaction. PMID:19711391

  18. Bright Sparks of Our Future!

    Science.gov (United States)

    Riordan, Naoimh

    2016-04-01

    My name is Naoimh Riordan and I am the Vice Principal of Rockboro Primary School in Cork City, South of Ireland. I am a full time class primary teacher and I teach 4th class, my students are aged between 9-10 years. My passion for education has developed over the years and grown towards STEM (Science, Technology, Engineering and Mathematics) subjects. I believe these subjects are the way forward for our future. My passion and beliefs are driven by the unique after school programme that I have developed. It is titled "Sparks" coming from the term Bright Sparks. "Sparks" is an after school programme with a difference where the STEM subjects are concentrated on through lessons such as Science, Veterinary Science Computer Animation /Coding, Eco engineering, Robotics, Magical Maths, Chess and Creative Writing. All these subjects are taught through activity based learning and are one-hour long each week for a ten-week term. "Sparks" is fully inclusive and non-selective which gives all students of any level of ability an opportunity to engage into these subjects. "Sparks" is open to all primary students in County Cork. The "Sparks" after school programme is taught by tutors from the different Universities and Colleges in Cork City. It works very well because the tutor brings their knowledge, skills and specialised equipment from their respective universities and in turn the tutor gains invaluable teaching practise, can trial a pilot programme in a chosen STEM subject and gain an insight into what works in the physical classroom.

  19. Designers predict a bright future

    International Nuclear Information System (INIS)

    As power plant designers and builders, there is a bright future for the industry. The demand for electricity will continue to grow, and the need for new plants will increase accordingly. But companies that develop and supply these plants must adapt to new ways of doing business if they expect to see the dawn of this new age. Several factors will have a profound effect on the generation and use of electricity in future years. Instant communications now reach all corners of the globe, making people everywhere aspire to a higher standard of living. The economic surge needed to satisfy these appetites will, in turn, be fed by a network of suppliers who are themselves restructuring to serve global markets, unimpeded by past nationalistic barriers to trade. The strong correlation between economic progress and the growing demand for electricity is well recognized. A ready supply of affordable electricity is a necessary underpinning for any economic expansion. As economies advance and jobs increase, electric demand grows geometrically, fueled by an ever-improving quality of life. Coupled with increasing demand is the worldwide trend toward privatization of the generation industry. The reasons may vary in different parts of the world, but the effect is the same--companies are battling intensely for the right to build or purchase generating facilities. Those companies, like the industry they serve, are themselves in a period of transition. Once a closed, monopolistic group of owners in a predominantly services-based market, they are, thanks to competitive forces, being driven steadily toward a product-based structure

  20. Fluorescent refrigeration

    Science.gov (United States)

    Epstein, Richard I.; Edwards, Bradley C.; Buchwald, Melvin I.; Gosnell, Timothy R.

    1995-01-01

    Fluorescent refrigeration is based on selective radiative pumping, using substantially monochromatic radiation, of quantum excitations which are then endothermically redistributed to higher energies. Ultimately, the populated energy levels radiatively deexcite emitting, on the average, more radiant energy than was initially absorbed. The material utilized to accomplish the cooling must have dimensions such that the exciting radiation is strongly absorbed, but the fluorescence may exit the material through a significantly smaller optical pathlength. Optical fibers and mirrored glasses and crystals provide this requirement.

  1. A fluorescence resonance energy transfer (FRET) based "Turn-On" nanofluorescence sensor using a nitrogen-doped carbon dot-hexagonal cobalt oxyhydroxide nanosheet architecture and application to α-glucosidase inhibitor screening.

    Science.gov (United States)

    Li, Guoliang; Kong, Weiheng; Zhao, Mei; Lu, Shuaimin; Gong, Peiwei; Chen, Guang; Xia, Lian; Wang, Hua; You, Jinmao; Wu, Yongning

    2016-05-15

    The medicines targeted at α-glucosidase played an important role in anti-diabetes and anti-HIV therapy. Unfortunately, the method based on fluorescent assay strategy for α-glucosidase inhibitor screening remains poorly investigated. In this study, a novel "Turn On" fluorescence sensor platform has been developed for trace α-glucosidase inhibitor screening from natural medicines. Firstly, carbon dots were prepared by one-pot synthesis and used as the signal output. Combining with the carbon dots, cobalt oxyhydroxide (CoOOH) nanoflakes were employed to build the fluorescence resonance energy transfer (FRET) based sensor platform. Secondly, L-ascorbic acid-2-O-α-D-glucopyranosyl (AAG) was innovatively introduced as α-glucosidase substrate. With hydrolysis of AAG by α-glucosidase, ascorbic acids (AA) were released that can rapidly reduce CoOOH nanoflakes to Co(2+), and then FRET was stopped accompanying with the fluorescence recovery of CDs. The sensor platform was ultrasensitive to AA with a detection limit of 5nM, ensuring the sensitive monitoring of enzyme activity. Acarbose was used as the inhibitor model and its inhibition rate is proportional to the logarithm of concentration in range of 10(-9)-10(-3)M with the correlation coefficient of R(2)=0.996, and an ultralow limit of detection of ~1×10(-9)M was obtained. The inhibiting ability of seven compounds isolated from natural medicines was also evaluated. The constructed sensor platform was proven to be sensitive and selective as well as cost-effective, facile and reliable, making it promising as a candidate for trace α-glucosidase inhibitor screening. PMID:26774085

  2. Bright boys the making of information technology

    CERN Document Server

    Green, Tom

    2010-01-01

    Everything has a beginning. None was more profound-and quite as unexpected-than Information Technology. Here for the first time is the untold story of how our new age came to be and the bright boys who made it happen. What began on the bare floor of an old laundry building eventually grew to rival in size the Manhattan Project. The unexpected consequence of that journey was huge---what we now know as Information Technology. For sixty years the bright boys have been totally anonymous while their achievements have become a way of life for all of us. "Bright Boys" brings them home. By 1950 they'd

  3. Formation of binary and ternary metal deposits on glass-ceramic carbon electrode surfaces: electron-probe X-ray microanalysis, total-reflection X-ray fluorescence analysis, X-ray photoelectron spectroscopy and scanning electron microscopy study

    International Nuclear Information System (INIS)

    The features of the formation of binary and ternary alloys during the electrochemical deposition and co-deposition of copper, cadmium and lead from aqueous solutions on disc glass-ceramic carbon electrode surfaces were studied by electron-probe X-ray microanalysis, total-reflection X-ray fluorescence analysis, X-ray photoelectron spectroscopy and scanning electron microscopy. The macroscopic properties of electrodeposits such as morphology, lateral distribution of the elements along the disc electrode surface and depth distribution of the elements in the electrodeposit bulk were established. The mechanisms of metal nucleation and growth of thin films of electrodeposits were discussed

  4. The solar brightness temperature at millimeter wavelengths

    Science.gov (United States)

    Kuseski, R. A.; Swanson, P. N.

    1976-01-01

    Measurements of the brightness temperature of the sun near 36 GHz and 93 GHz were made using the new moon as a calibration source. Provided the brightness temperature of the moon is known and all measurements are reduced to the same zenith angle, a simple expression can be used for the sun-to-new moon ratio which is independent of antenna gain, atmospheric absorption and reemission, and radiometer calibration constants. This ratio was measured near 36 GHz and at two frequencies near 93 GHz with a Dicke switched superheterodyne radiometer system and a 2.4 m Cassegrain antenna. The slopes of the solar brightness temperature spectrum based on these ratios were measured. The absolute solar brightness spectrum derived from all current available measurements supplemented by the present ones is also plotted and discussed.

  5. A spectroscopic atlas of bright stars

    CERN Document Server

    Martin, Jack

    2009-01-01

    Suitable for amateur astronomers interested in practical spectroscopy or spectrography, this reference book identifies more than 70 (northern hemisphere) bright stars that are suitable observational targets. It provides finder charts for locating these sometimes-familiar stars.

  6. Surface Brightness Profiles of Seyfert Galaxies

    CERN Document Server

    Tugay, A V

    2014-01-01

    We built r-band surface brightness profiles by SDSS data for 16 Seyfert galaxies observed in Crimean Astrophysical Observatory. Obtained profiles can be used for finding more accurate lightcurves for these galaxies.

  7. Brightness of synchrotron radiation from wigglers

    CERN Document Server

    Geloni, Gianluca; Saldin, Evgeni

    2014-01-01

    According to literature, while calculating the brightness of synchrotron radiation from wigglers, one needs to account for the so called `depth-of-field' effects. In fact, the particle beam cross section varies along the wiggler. It is usually stated that the effective photon source size increases accordingly, while the brightness is reduced. Here we claim that this is a misconception originating from an analysis of the wiggler source based on geometrical arguments, regarded as almost self-evident. According to electrodynamics, depth-of-field effects do not exist: we demonstrate this statement both theoretically and numerically, using a well-known first-principle computer code. This fact shows that under the usually accepted approximations, the description of the wiggler brightness turns out to be inconsistent even qualitatively. Therefore, there is a need for a well-defined procedure for computing the brightness from a wiggler source. We accomplish this task based on the use of a Wigner function formalism. I...

  8. Safranine fluorescent staining of wood cell walls.

    Science.gov (United States)

    Bond, J; Donaldson, L; Hill, S; Hitchcock, K

    2008-06-01

    Safranine is an azo dye commonly used for plant microscopy, especially as a stain for lignified tissues such as xylem. Safranine fluorescently labels the wood cell wall, producing green/yellow fluorescence in the secondary cell wall and red/orange fluorescence in the middle lamella (ML) region. We examined the fluorescence behavior of safranine under blue light excitation using a variety of wood- and fiber-based samples of known composition to interpret the observed color differentiation of different cell wall types. We also examined the basis for the differences in fluorescence emission using spectral confocal microscopy to examine lignin-rich and cellulose-rich cell walls including reaction wood and decayed wood compared to normal wood. Our results indicate that lignin-rich cell walls, such as the ML of tracheids, the secondary wall of compression wood tracheids, and wood decayed by brown rot, tend to fluoresce red or orange, while cellulose-rich cell walls such as resin canals, wood decayed by white rot, cotton fibers and the G-layer of tension wood fibers, tend to fluoresce green/yellow. This variation in fluorescence emission seems to be due to factors including an emission shift toward red wavelengths combined with dye quenching at shorter wavelengths in regions with high lignin content. Safranine fluorescence provides a useful way to differentiate lignin-rich and cellulose-rich cell walls without counterstaining as required for bright field microscopy. PMID:18802812

  9. The surface brightness of spiral galaxies

    International Nuclear Information System (INIS)

    The intrinsic surface brightness Ssub(e) of 500 disc galaxies (0<=T<=9) drawn from the Second Reference Catalogue is computed and it is shown that Ssub(e) does not correlate significantly with Msub(B), (B-V) or type. This is consistent with the notion that there is a heavy selection bias in favour of disc galaxies with that particular surface brightness which allows inclusion in the catalogue over the largest volume of space. (author)

  10. The surface brightness of spiral galaxies

    International Nuclear Information System (INIS)

    It is proposed that Freeman's discovery that the extrapolated central surface brightness of spiral galaxies is approximately constant can be simply explained if the galaxies contain a spheroidal component which dominates the light in their outer isophotes. Calculations of an effective central surface brightness indicate a wide spread of values. This requires either a wide spread in disc properties or significant spheroidal components or, most probably, both. (author)

  11. Development of a high brightness ion source

    International Nuclear Information System (INIS)

    The brightness and emittance of an ion beam can depend on the ion temperature, aberrations and scattering, as well as other factors. However, it is the ion temperature which determines the irreducible minimum value of the emittance and hence brightness, as the other components can be eliminated by careful design. An ion source design is presented which has attained this minimum value for the emittance; the dependence of the ion temperature on the plasma source parameters is discussed

  12. Bright perspectives for nuclear photonics

    International Nuclear Information System (INIS)

    With the advent of new high-power, short-pulse laser facilities in combination with novel technologies for the production of highly brilliant, intense γ beams (like, e.g., Extreme Light Infrastructure - Nuclear Physics (ELI-NP) in Bucharest, MEGaRay in Livermore or a planned upgrade of the HIγS facility at Duke University), unprecedented perspectives will open up in the coming years for photonuclear physics both in basic sciences as in various fields of applications. Ultra-high sensitivity will be enabled by an envisaged increase of the γ-beam spectral density from the presently typical 102γ/eVs to about 104γ/eVs, thus enabling a new quality of nuclear photonics, assisted by new γ-optical elements. Photonuclear reactions with highly brilliant γ beams will allow to produce radioisotopes for nuclear medicine with much higher specific activity and/or more economically than with conventional methods. This will open the door for completely new clinical applications of radioisotopes. The isotopic, state-selective sensitivity of the well-established technique of nuclear resonance fluorescence (NRF) will be boosted by the drastically reduced energy bandwidth (<0.1%) of the novel γ beams. Together with a much higher intensity of these beams, this will pave the road towards a γ-beam based non-invasive tomography and microscopy, assisting the management of nuclear materials, such as radioactive waste management, the detection of nuclear fissile material in the recycling process or the detection of clandestine fissile materials. Moreover, also secondary sources like low-energy, pulsed, polarized neutron beams of high intensity and high brilliance or a new type of positron source with significantly increased brilliance, for the first time fully polarized, can be realized and lead to new applications in solid state physics or material sciences. (authors)

  13. Molecular basis of photochromism of a fluorescent protein revealed by direct {sup 13}C detection under laser illumination

    Energy Technology Data Exchange (ETDEWEB)

    Mizuno, Hideaki, E-mail: hideaki.mizuno@chem.kuleuven.be; Mal, Tapas Kumar [Katholieke Universiteit Leuven, Department of Chemistry and INPAC (Belgium); Waelchli, Markus [Bruker BioSpin K.K (Japan); Fukano, Takashi [Brain Science Institute, RIKEN, Cell Function and Dynamics (Japan); Ikura, Mitsuhiko [University of Toronto, MaRS Toronto Medical Dicovery Tower, Division of Signaling Biology, Ontario Cancer Institute and Department of Medical Biophysics (Canada); Miyawaki, Atsushi, E-mail: matsushi@brain.riken.j [Brain Science Institute, RIKEN, Cell Function and Dynamics (Japan)

    2010-12-15

    Dronpa is a green fluorescent protein homologue with a photochromic property. A green laser illumination reversibly converts Dronpa from a green-emissive bright state to a non-emissive dark state, and ultraviolet illumination converts it to the bright state. We have employed solution NMR to understand the underlying molecular mechanism of the photochromism. The detail characterization of Dronpa is hindered as it is metastable in the dark state and spontaneously converts to the bright state. To circumvent this issue, we have designed in magnet laser illumination device. By combining the device with a 150-mW argon laser at 514.5 nm, we have successfully converted and maintained Dronpa in the dark state in the NMR tube by continuous illumination during the NMR experiments. We have employed direct-detection of {sup 13}C nuclei from the carbon skeleton of the chromophore for detailed characterization of chromophore in both states of Dronpa by using the Bruker TCI cryoprobe. The results from NMR data have provided direct evidence of the double bond formation between C{sup {alpha}} and C{sup {beta}} of Y63 in the chromophore, the {beta}-barrel structure in solution, and the ionized and protonated state of Y63 hydroxyl group in the bright and dark states, respectively. These studies have also revealed that a part of {beta}-barrel around the chromophore becomes polymorphic only in the dark state, which may be critical to make the fluorescence dim by increasing the contribution of non-emissive vibrational relaxation pathways.

  14. Energy-exchange collisions of dark-bright-bright vector solitons.

    Science.gov (United States)

    Radhakrishnan, R; Manikandan, N; Aravinthan, K

    2015-12-01

    We find a dark component guiding the practically interesting bright-bright vector one-soliton to two different parametric domains giving rise to different physical situations by constructing a more general form of three-component dark-bright-bright mixed vector one-soliton solution of the generalized Manakov model with nine free real parameters. Moreover our main investigation of the collision dynamics of such mixed vector solitons by constructing the multisoliton solution of the generalized Manakov model with the help of Hirota technique reveals that the dark-bright-bright vector two-soliton supports energy-exchange collision dynamics. In particular the dark component preserves its initial form and the energy-exchange collision property of the bright-bright vector two-soliton solution of the Manakov model during collision. In addition the interactions between bound state dark-bright-bright vector solitons reveal oscillations in their amplitudes. A similar kind of breathing effect was also experimentally observed in the Bose-Einstein condensates. Some possible ways are theoretically suggested not only to control this breathing effect but also to manage the beating, bouncing, jumping, and attraction effects in the collision dynamics of dark-bright-bright vector solitons. The role of multiple free parameters in our solution is examined to define polarization vector, envelope speed, envelope width, envelope amplitude, grayness, and complex modulation of our solution. It is interesting to note that the polarization vector of our mixed vector one-soliton evolves in sphere or hyperboloid depending upon the initial parametric choices. PMID:26764780

  15. Energy-exchange collisions of dark-bright-bright vector solitons

    Science.gov (United States)

    Radhakrishnan, R.; Manikandan, N.; Aravinthan, K.

    2015-12-01

    We find a dark component guiding the practically interesting bright-bright vector one-soliton to two different parametric domains giving rise to different physical situations by constructing a more general form of three-component dark-bright-bright mixed vector one-soliton solution of the generalized Manakov model with nine free real parameters. Moreover our main investigation of the collision dynamics of such mixed vector solitons by constructing the multisoliton solution of the generalized Manakov model with the help of Hirota technique reveals that the dark-bright-bright vector two-soliton supports energy-exchange collision dynamics. In particular the dark component preserves its initial form and the energy-exchange collision property of the bright-bright vector two-soliton solution of the Manakov model during collision. In addition the interactions between bound state dark-bright-bright vector solitons reveal oscillations in their amplitudes. A similar kind of breathing effect was also experimentally observed in the Bose-Einstein condensates. Some possible ways are theoretically suggested not only to control this breathing effect but also to manage the beating, bouncing, jumping, and attraction effects in the collision dynamics of dark-bright-bright vector solitons. The role of multiple free parameters in our solution is examined to define polarization vector, envelope speed, envelope width, envelope amplitude, grayness, and complex modulation of our solution. It is interesting to note that the polarization vector of our mixed vector one-soliton evolves in sphere or hyperboloid depending upon the initial parametric choices.

  16. Phenyl-Modified Carbon Nitride Quantum Dots with Distinct Photoluminescence Behavior.

    Science.gov (United States)

    Cui, Qianling; Xu, Jingsan; Wang, Xiaoyu; Li, Lidong; Antonietti, Markus; Shalom, Menny

    2016-03-01

    A novel type of quantum dot (Ph-CN) is manufactured from graphitic carbon nitride by "lining" the carbon nitride structure with phenyl groups through supramolecular preorganization. This approach requires no chemical etching or hydrothermal treatments like other competing nanoparticle syntheses and is easy and safe to use. The Ph-CN nanoparticles exhibit bright, tunable fluorescence, with a high quantum yield of 48.4 % in aqueous colloidal suspensions. Interestingly, the observed Stokes shift of approximately 200 nm is higher than the maximum values reported for carbon nitride based fluorophores. The high quantum yield and the large Stokes shift are related to the structural surface organization of the phenyl groups, which affects the π-electron delocalization in the conjugated carbon nitride networks and induces colloidal stability. The remarkable performance of the Ph-CN nanoparticles in imaging is demonstrated by a simple incubation study with HeLa cells. PMID:26880237

  17. Fluorescent nanoparticles based on AIE fluorogens for bioimaging

    Science.gov (United States)

    Yan, Lulin; Zhang, Yan; Xu, Bin; Tian, Wenjing

    2016-01-01

    Fluorescent nanoparticles (FNPs) have recently attracted increasing attention in the biomedical field because of their unique optical properties, easy fabrication and outstanding performance in imaging. Compared with conventional molecular probes including small organic dyes and fluorescent proteins, FNPs based on aggregation-induced emission (AIE) fluorogens have shown significant advantages in tunable emission and brightness, good biocompatibility, superb photo- and physical stability, potential biodegradability and facile surface functionalization. In this review, we summarize the latest advances in the development of fluorescent nanoparticles based on AIE fluorogens including polymer nanoparticles and silica nanoparticles over the past few years, and the various biomedical applications based on these fluorescent nanoparticles are also elaborated.

  18. Remote sensing of terrestrial chlorophyll fluorescence from space

    OpenAIRE

    Frankenberg, Christian; Berry, Joseph; Guanter, Luis; JOINER Joanna

    2013-01-01

    High-resolution spectrometers enable new avenues in global carbon cycle research, including the first accurate retrievals of chlorophyll fluorescence from space as an indicator of photosynthetic activity.

  19. Water electrolysis with a conducting carbon cloth: subthreshold hydrogen generation and superthreshold carbon quantum dot formation.

    Science.gov (United States)

    Biswal, Mandakini; Deshpande, Aparna; Kelkar, Sarika; Ogale, Satishchandra

    2014-03-01

    A conducting carbon cloth, which has an interesting turbostratic microstructure and functional groups that are distinctly different from other ordered forms of carbon, such as graphite, graphene, and carbon nanotubes, was synthesized by a simple one-step pyrolysis of cellulose fabric. This turbostratic disorder and surface chemical functionalities had interesting consequences for water splitting and hydrogen generation when such a cloth was used as an electrode in the alkaline electrolysis process. Importantly, this work also gives a new twist to carbon-assisted electrolysis. During electrolysis, the active sites in the carbon cloth allow slow oxidation of its surface to transform the surface groups from COH to COOH and so forth at a voltage as low as 0.2 V in a two-electrode system, along with platinum as the cathode, instead of 1.23 V (plus overpotential), which is required for platinum, steel, or even graphite anodes. The quantity of subthreshold hydrogen evolved was 24 mL cm(-2)  h(-1) at 1 V. Interestingly, at a superthreshold potential (>1.23 V+overpotential), another remarkable phenomenon was found. At such voltages, along with the high rate and quantity of hydrogen evolution, rapid exfoliation of the tiny nanoscale (5-7 nm) units of carbon quantum dots (CQDs) are found in copious amounts due to an enhanced oxidation rate. These CQDs show bright-blue fluorescence under UV light. PMID:24492961

  20. Color-Multiplexing-Based Fluorescent Test Paper: Dosage-Sensitive Visualization of Arsenic(III) with Discernable Scale as Low as 5 ppb.

    Science.gov (United States)

    Zhou, Yujie; Huang, Xiaoyan; Liu, Cui; Zhang, Ruilong; Gu, Xiaoling; Guan, Guijian; Jiang, Changlong; Zhang, Liying; Du, Shuhu; Liu, Bianhua; Han, Ming-Yong; Zhang, Zhongping

    2016-06-21

    Fluorescent colorimetry test papers are promising for the assays of environments, medicines, and foods by the observation of the naked eye on the variations of fluorescence brightness and color. Unlike dye-absorption-based pH test paper, however, the fluorescent test papers with wide color-emissive variations with target dosages for accurate quantification remain unsuccessful even if the multicolorful fluorescent probes are used. Here, we report the dosage-sensitive fluorescent colorimetry test paper with a very wide/consecutive "from red to cyan" response to the presence and amount of arsenic ions, As(III). Red quantum dots (QDs) were modified with glutathione and dithiothreitol to obtain the supersensitivity to As(III) by the quenching of red fluorescence through the formation of dispersive QDs aggregates. A small amount of cyan carbon dots (CDs) with spectral blue-green components as the photostable internal standard were mixed into the QDs solution to produce a composited red fluorescence. Upon the addition of As(III) into the sensory solution, the fluorescence color could gradually be reversed from red to cyan with a detection limit of 1.7 ppb As(III). When the sensory solution was printed onto a piece of filter paper, surprisingly a serial of color evolution from peach to pink to orange to khaki to yellowish to yellow-green to final cyan with the addition of As(III) was displayed and clearly discerned the dosage scale as low as 5 ppb. The methodology reported here opens a novel pathway toward the real applications of fluorescent test papers. PMID:27230307

  1. Response of carbon assimilation and chlorophyll fluorescence to soybean leaf phosphorus across CO2: Alternative electron sink, nutrient efficiency and critical phosphorus concentration

    Science.gov (United States)

    To evaluate the response of CO2 assimilation (PN) and various chlorophyll fluorescence (CF) parameters to phosphorus (P) nutrition soybean plants were grown in controlled environment growth chambers with sufficient (0.50 mM) and deficient (0.10 and 0.01 mM) P supply under ambient and elevated CO2 (a...

  2. Spectroscopic Surface Brightness Fluctuations: Amplifying Bright Stars in Unresolved Stellar Populations

    Science.gov (United States)

    Mitzkus, M.; Dreizler, S.; Roth, M. M.

    2015-08-01

    We report on our early-stage efforts to resolve the Surface Brightness Fluctuations (SBFs) in the spectral dimension. Combining the diagnostic power of SBFs with the physical information content of spectra seems a tempting possibility to gain new insights into the bright stars in unresolved stellar populations. The new VLT integral field spectrograph MUSE is the first instrument that enables spectroscopic SBFs observationally.

  3. Preparation of carbon quantum dots based on starch and their spectral properties.

    Science.gov (United States)

    Yan, Zhengyu; Shu, Juan; Yu, Yan; Zhang, Zhengwei; Liu, Zhen; Chen, Jianqiu

    2015-06-01

    A simple method for the synthesis of water-soluble carbon quantum dots (CQDs) has been developed based on chemical oxidation of starch. The structures and optical properties of the CQDs were characterized by ultraviolet-visible (UV-Vis) spectroscopy, photoluminescence spectroscopy (PL) and transmission electron microscopy. The CQDs were found to emit bright blue fluorescence and disperse uniformly. The effects of ambient temperature, light and pH on the properties of CQDs were studied. The CQDs exhibited good chemical stability, good photostability and pH sensitivity. Furthermore, the interaction between CQDs and bovine serum albumin (BSA) was investigated. PMID:25044549

  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. Observing Faint Companions Close to Bright Stars

    Science.gov (United States)

    Serabyn, Eugene

    2012-04-01

    Progress in a number of technical areas is enabling imaging and interferometric observations at both smaller angular separations from bright stars and at deeper relative contrast levels. Here we discuss recent progress in several ongoing projects at the Jet Propulsion Laboratory. First, extreme adaptive optics wavefront correction has recently enabled the use of very short (i.e., blue) wavelengths to resolve close binaries. Second, phase-based coronagraphy has recently allowed observations of faint companions to within nearly one diffraction beam width of bright stars. Finally, rotating interferometers that can observe inside the diffraction beam of single aperture telescopes are being developed to detect close-in companions and bright exozodiacal dust. This paper presents a very brief summary of the techniques involved, along with some illustrative results.

  6. High brightness semiconductor lasers with reduced filamentation

    DEFF Research Database (Denmark)

    McInerney, John; O'Brien, Peter.; Skovgaard, Peter M. W.; Houlihan, John; Mullane, Mark; O'Neill, Eamonn

    High brightness semiconductor lasers have applications in spectroscopy, fiber lasers, manufacturing and materials processing, medicine and free space communication or energy transfer. The main difficulty associated with high brightness is that, because of COD, high power requires a large aperture....... Large apertures result in high order transverse modes, filamentation and spatio-temporal instabilities, all of which degrade spatial coherence and therefore brightness. We shall describe a combined assault on three fronts: (1) minimise aperture size required for a given power by maximising the facet...... damage threshold, (2) for a given aperture, minimise self-focusing and filamentation by minimising the effective nonlinear coefficient (the alpha parameter), and (3) for a given aperture and nonlinear coefficient, develop optical cavities and propagation structures to suppress filamentation and high...

  7. High brightness semiconductor lasers with reduced filamentation

    DEFF Research Database (Denmark)

    McInerney, John; O'Brien, Peter.; Skovgaard, Peter M. W.;

    1999-01-01

    High brightness semiconductor lasers have applications in spectroscopy, fiber lasers, manufacturing and materials processing, medicine and free space communication or energy transfer. The main difficulty associated with high brightness is that, because of COD, high power requires a large aperture....... Large apertures result in high order transverse modes, filamentation and spatio-temporal instabilities, all of which degrade spatial coherence and therefore brightness. We shall describe a combined assault on three fronts: (1) minimise aperture size required for a given power by maximising the facet...... damage threshold, (2) for a given aperture, minimise self-focusing and filamentation by minimising the effective nonlinear coefficient (the alpha parameter), and (3) for a given aperture and nonlinear coefficient, develop optical cavities and propagation structures to suppress filamentation and high...

  8. Increasing the brightness of light sources

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Ling

    2006-11-16

    In this work the principle of light recycling is applied to artificial light sources in order to achieve brightness enhancement. Firstly, the feasibilities of increasing the brightness of light sources via light recycling are examined theoretically, based on the fundamental laws of thermodynamics including Kirchhoff's law on radiation, Planck's law, Lambert-Beer's law, the etendue conservation and the brightness theorem. From an experimental viewpoint, the radiation properties of three different kinds of light sources including short-arc lamps, incandescent lamps and LEDs characterized by their light-generating mechanisms are investigated. These three types of sources are used in light recycling experiments, for the purpose of 1. validating the intrinsic light recycling effect in light sources, e. g. the intrinsic light recycling effect in incandescent lamps stemming from the coiled filament structure. 2. acquiring the required parameters for establishing physical models, e.g. the emissivity/absorptivity of the short-arc lamps, the intrinsic reflectivity and the external quantum efficiency of LEDs. 3. laying the foundations for designing optics aimed at brightness enhancement according to the characteristics of the sources and applications. Based on the fundamental laws and experiments, two physical models for simulating the radiance distribution of light sources are established, one for thermal filament lamps, the other for luminescent sources, LEDs. As validation of the theoretical and experimental investigation of the light recycling effect, an optical device, the Carambola, is designed for achieving deterministic and multiple light recycling. The Carambola has the function of a concentrator. In order to achieve the maximum possible brightness enhancement with the Carambola, several combinations of sources and Carambolas are modelled in ray-tracing simulations. Sources with different light-emitting mechanisms and different radiation properties

  9. The historical investigation of cometary brightness

    Science.gov (United States)

    Hughes, David W.

    1998-12-01

    The interpretation of the way in which the brightness of a comet varied as a function of both its heliocentric and geocentric distance was essentially started by Isaac Newton in his book Philosophiae Naturalis Principia Mathematica, published in 1687. Astronomers have argued about the form of this variability ever since, and for many years it was regarded as an important clue as to the physical nature of the cometary nucleus and its decay process. This paper reviews our understanding of the causes of cometary brightness variability between about 1680 and the 1950s.

  10. The environment of Low Surface Brightness Galaxies

    OpenAIRE

    Rosenbaum, S. D.; Bomans, D. J.

    2004-01-01

    Using the Early Data Release of the Sloan Digital Sky Survey (SDSS) we investigated the clustering properties of Low Surface Brightness (LSB) galaxies in comparison to normal, High Surface Brightness (HSB) galaxies. We selected LSB galaxies and HSB galaxies with well measured redshifts from the SDSS data base and performed three-dimensional neighbour counting analysis within spheres of radii between 0.8 Mpc and 8.0 Mpc. As a second analysis method we used an N-th neighbour analysis with N var...

  11. Discovery program for bright quasars: preliminary results

    International Nuclear Information System (INIS)

    A program has been undertaken to obtain a complete sample of bright quasars on the basis of ultraviolet color excess. Spectroscopic examination of candidates selected from two-color Schmidt telescope films has yielded four new quasars brighter than B = 16/sup m/5, with the candidate list containing two more previously identified. Magnitudes, color indices, and redshifts are presented for the new discoveries, along with positions and finding charts. Although the sample is not yet complete, these first results suggest that bright quasars have a low surface density

  12. Localization and relative quantification of carbon nanotubes in cells with multispectral imaging flow cytometry.

    Science.gov (United States)

    Marangon, Iris; Boggetto, Nicole; Ménard-Moyon, Cécilia; Luciani, Nathalie; Wilhelm, Claire; Bianco, Alberto; Gazeau, Florence

    2013-01-01

    Carbon-based nanomaterials, like carbon nanotubes (CNTs), belong to this type of nanoparticles which are very difficult to discriminate from carbon-rich cell structures and de facto there is still no quantitative method to assess their distribution at cell and tissue levels. What we propose here is an innovative method allowing the detection and quantification of CNTs in cells using a multispectral imaging flow cytometer (ImageStream, Amnis). This newly developed device integrates both a high-throughput of cells and high resolution imaging, providing thus images for each cell directly in flow and therefore statistically relevant image analysis. Each cell image is acquired on bright-field (BF), dark-field (DF), and fluorescent channels, giving access respectively to the level and the distribution of light absorption, light scattered and fluorescence for each cell. The analysis consists then in a pixel-by-pixel comparison of each image, of the 7,000-10,000 cells acquired for each condition of the experiment. Localization and quantification of CNTs is made possible thanks to some particular intrinsic properties of CNTs: strong light absorbance and scattering; indeed CNTs appear as strongly absorbed dark spots on BF and bright spots on DF with a precise colocalization. This methodology could have a considerable impact on studies about interactions between nanomaterials and cells given that this protocol is applicable for a large range of nanomaterials, insofar as they are capable of absorbing (and/or scattering) strongly enough the light. PMID:24378540

  13. Localized Excitons in Carbon Nanotubes.

    Science.gov (United States)

    Adamska, Lyudmyla; Doorn, Stephen K.; Tretiak, Sergei

    2015-03-01

    It has been historically known that unintentional defects in carbon nanotubes (CNTs) may fully quench the fluorescence. However, some dopants may enhance the fluorescence by one order of magnitude thus turning the CNTs, which are excellent light absorbers, in good emitters. We have correlated the experimentally observed photoluminescence spectra to the electronic structure simulations. Our experiment reveals multiple sharp asymmetric emission peaks at energies 50-300 meV red-shifted from that of the lowest bright exciton peak. Our simulations suggest an association of these peaks with deep trap states tied to different specific chemical adducts. While the wave functions of excitons in undoped CNTs are delocalized, those of the deep-trap states are strongly localized and pinned to the dopants. These findings are consistent with the experimental observation of asymmetric broadening of the deep trap emission peaks, which can result from scattering of acoustic phonons on localized excitons. Our work lays the foundation to utilize doping as a generalized route for wave function engineering and direct control of carrier dynamics in SWCNTs toward enhanced light emission properties for photonic applications.

  14. A Magnetic Bright Point Case Study

    Czech Academy of Sciences Publication Activity Database

    Utz, D.; Jurčák, Jan; Bellot Rubio, L.; del Toro Iniesta, J.C.; Thonhofer, S.; Hanslmeier, A.; Veronig, A.; Muller, R.; Lemmerer, B.

    2013-01-01

    Roč. 37, č. 2 (2013), s. 459-470. ISSN 1845-8319. [Hvar Astrophysical Colloquium /12./. Hvar, 03.09.2012-07.09.2012] R&D Projects: GA MŠk(CZ) MEB061109 Institutional support: RVO:67985815 Keywords : solar magnetic field * magnetic bright points * sunrise/IMaX Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  15. A photometric investigation of a bright Geminid

    NARCIS (Netherlands)

    Degewij, J.; Diggelen, Johannes van

    1968-01-01

    Photographic observations of meteors in the Netherlands started with a bright Geminid of photographic magnitude −8 observed on December 11, 1955, 21h39m55s by M. Alberts. From the assumed radiant and velocity we have constructed the trajectory of the bolide. The luminosity of the trail has been dete

  16. Brightness versus roughness: a multiscale approach

    International Nuclear Information System (INIS)

    A link between roughness and brightness is sought for brass specimens that were superfinished, sandblasted and brushed. Only the blasting conditions are varied in order to get different roughness and brightness. First, a relation between roughness and brightness is sought for specimens that were superfinished and sandblasted. The best relation is obtained using the mean height of the motifs, calculated using a low-pass filter and cut-off length equal to 30 μm, with a logarithmic–logarithmic model. Then, the same type of relation is determined after superfinishing sandblasting and brushing. The core material volume Vmc, computed using a high-pass filter with a cut-off length of 60 μm and a linear–logarithmic relationship, gives the best results. A relation between roughness and brightness that is common to both the pre-brushing state and post-brushing state is identified: the best roughness parameter is the arithmetic mean deviation Sa using a high-pass filter with a cut-off of 15 μm, with a logarithmic–logarithmic relationship. Finally, it is shown that the use of these filtering conditions enables us to verify the model of Beckmann and Spizzichino for the examined specimens. This scale corresponds to the end of the fractal regime and is close to the end of the signal correlation. (paper)

  17. Discussion of high brightness rf linear accelerators

    International Nuclear Information System (INIS)

    The fundamental aspects of high-brightness rf linacs are outlined, showing the breadth and complexity of the technology and indicating that synergism with advancements in other areas is important. Areas of technology reviewed include ion sources, injectors, rf accelerator structures, beam dynamics, rf power, and automatic control

  18. Circadian Phase-Shifting Effects of Bright Light, Exercise, and Bright Light + Exercise

    OpenAIRE

    Youngstedt, Shawn D.; Kline, Christopher E.; Elliott, Jeffrey A; Zielinski, Mark; Devlin, Tina M.; Moore, Teresa A.

    2016-01-01

    Limited research has compared the circadian phase-shifting effects of bright light and exercise and additive effects of these stimuli. The aim of this study was to compare the phase-delaying effects of late night bright light, late night exercise, and late evening bright light followed by early morning exercise. In a within-subjects, counterbalanced design, 6 young adults completed each of three 2.5-day protocols. Participants followed a 3-h ultra-short sleep-wake cycle, involving wakefulness...

  19. Conservation of an ion beam brightness. Study of a non brightness disturbing lens

    International Nuclear Information System (INIS)

    Experimental studies of ion sources prove that large initial brightnesses can be obtained by using the plasma expansion principle. However these brightnesses are usually spoiled by the beam focusing and accelerating systems. A high intensity focusing set up is first theoretically studied, then numerically determined by use of a 7094 IBM computer. Aberrations have been minimized. It has then been possible to construct a set up conserving the source initial brightness. For a 100 mA beam the focusing voltage is 150 kV, the beam study has been done for 350 keV beam final energy. Given is a discussion of results. (author)

  20. Fabrication of bright and small size semiconducting polymer nanoparticles for cellular labelling and single particle tracking

    Science.gov (United States)

    Wei, Lin; Zhou, Peng; Yang, Qingxiu; Yang, Qiaoyu; Ma, Ming; Chen, Bo; Xiao, Lehui

    2014-09-01

    In this work, we demonstrate a convenient and robust strategy for efficient fabrication of high fluorescence quantum yield (QY, 49.8 +/- 3%) semiconducting polymer nanoparticles (SPNs), with size comparable with semiconductor quantum dots (Qdots). The SPNs were synthesized by co-precipitation of hydrophobic semiconducting polymer together with amphiphilic multidentate polymer. Comprehensive spectroscopic and microscopic characterizations showed that the SPNs possess superior photophysical performance, with excellent fluorescence brightness and reduced photoblinking in contrast with Qdots, as well as good photostability compared to a fluorescent protein of a similar size, phycoerythrin. More importantly, by conjugating membrane biomarkers onto the surface of SPNs, it was found that they were not only suitable for specific cellular labelling but also for single particle tracking because of the improved optical performance.In this work, we demonstrate a convenient and robust strategy for efficient fabrication of high fluorescence quantum yield (QY, 49.8 +/- 3%) semiconducting polymer nanoparticles (SPNs), with size comparable with semiconductor quantum dots (Qdots). The SPNs were synthesized by co-precipitation of hydrophobic semiconducting polymer together with amphiphilic multidentate polymer. Comprehensive spectroscopic and microscopic characterizations showed that the SPNs possess superior photophysical performance, with excellent fluorescence brightness and reduced photoblinking in contrast with Qdots, as well as good photostability compared to a fluorescent protein of a similar size, phycoerythrin. More importantly, by conjugating membrane biomarkers onto the surface of SPNs, it was found that they were not only suitable for specific cellular labelling but also for single particle tracking because of the improved optical performance. Electronic supplementary information (ESI) available: Experimental section and additional supporting results as noted in the text

  1. Membrane Permeable Esterase–Activated Fluorescent Imaging Probe

    OpenAIRE

    Kim, Youngmi; Choi, Yongdoo; Weissleder, Ralph; Tung, Ching-Hsuan

    2007-01-01

    An esterase-triggered probe 2 derived from a cyanine-based pH sensitive dye was developed for cell labeling. Permeation of probe 2 into cells and subsequent hydrolytic activation by cellular esterases result in a bright fluorescent intracellular signal.

  2. Circadian Phase-Shifting Effects of Bright Light, Exercise, and Bright Light + Exercise.

    Science.gov (United States)

    Youngstedt, Shawn D; Kline, Christopher E; Elliott, Jeffrey A; Zielinski, Mark R; Devlin, Tina M; Moore, Teresa A

    2016-01-01

    Limited research has compared the circadian phase-shifting effects of bright light and exercise and additive effects of these stimuli. The aim of this study was to compare the phase-delaying effects of late night bright light, late night exercise, and late evening bright light followed by early morning exercise. In a within-subjects, counterbalanced design, 6 young adults completed each of three 2.5-day protocols. Participants followed a 3-h ultra-short sleep-wake cycle, involving wakefulness in dim light for 2h, followed by attempted sleep in darkness for 1 h, repeated throughout each protocol. On night 2 of each protocol, participants received either (1) bright light alone (5,000 lux) from 2210-2340 h, (2) treadmill exercise alone from 2210-2340 h, or (3) bright light (2210-2340 h) followed by exercise from 0410-0540 h. Urine was collected every 90 min. Shifts in the 6-sulphatoxymelatonin (aMT6s) cosine acrophase from baseline to post-treatment were compared between treatments. Analyses revealed a significant additive phase-delaying effect of bright light + exercise (80.8 ± 11.6 [SD] min) compared with exercise alone (47.3 ± 21.6 min), and a similar phase delay following bright light alone (56.6 ± 15.2 min) and exercise alone administered for the same duration and at the same time of night. Thus, the data suggest that late night bright light followed by early morning exercise can have an additive circadian phase-shifting effect. PMID:27103935

  3. Fluorescent probe based on heteroatom containing styrylcyanine: pH-sensitive properties and bioimaging in vivo

    International Nuclear Information System (INIS)

    A novel fluorescent probe based on heteroatom containing styrylcyanine is synthesized. The fluorescence of probe is bright green in basic and neutral media but dark orange in strong acidic environments, which could be reversibly switched. Such behavior enables it to work as a fluorescent pH sensor in the solution state and a chemosensor for detecting acidic and basic volatile organic compounds. Analyses by NMR spectroscopy confirm that the protonation or deprotonation of pyridinyl moiety is responsible for the sensing process. In addition, the fluorescent microscopic images of probe in live cells and zebrafish are achieved successfully, suggesting that the probe has good cell membrane permeability and low cytotoxicity. - Graphical abstract: A novel styrylcyanine-based fluorescent pH probe was designed and synthesized, the fluorescence of which is bright green in basic and neutral media but dark orange in strong acidic environments. Such behavior enables it to work as a fluorescent pH sensor in solution states, and a chemosensor for detecting volatile organic compounds with high acidity and basicity in solid state. In addition, it can be used for fluorescent imaging in living cell and living organism. - Highlights: • Bright green fluorescence was observed in basic and neutral media. • Dark orange fluorescence was found in strong acidic environments. • Volatile organic compounds with high acidity and basicity could be detected. • Bioimaging in living cell and living organism was achieved successfully

  4. Fluorescent probe based on heteroatom containing styrylcyanine: pH-sensitive properties and bioimaging in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xiaodong [School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640 (China); Gao, Ya; Huang, Zhibing; Chen, Xiaohui; Ke, Zhiyong [School of Basic Medical Science, Southern Medical University, Guangzhou 510515 (China); Zhao, Peiliang; Yan, Yichen [Department of Organic Pharmaceutical Chemistry, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515 (China); Liu, Ruiyuan, E-mail: ruiyliu@smu.edu.cn [Department of Organic Pharmaceutical Chemistry, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515 (China); Qu, Jinqing, E-mail: cejqqu@scut.edu.cn [School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640 (China)

    2015-07-01

    A novel fluorescent probe based on heteroatom containing styrylcyanine is synthesized. The fluorescence of probe is bright green in basic and neutral media but dark orange in strong acidic environments, which could be reversibly switched. Such behavior enables it to work as a fluorescent pH sensor in the solution state and a chemosensor for detecting acidic and basic volatile organic compounds. Analyses by NMR spectroscopy confirm that the protonation or deprotonation of pyridinyl moiety is responsible for the sensing process. In addition, the fluorescent microscopic images of probe in live cells and zebrafish are achieved successfully, suggesting that the probe has good cell membrane permeability and low cytotoxicity. - Graphical abstract: A novel styrylcyanine-based fluorescent pH probe was designed and synthesized, the fluorescence of which is bright green in basic and neutral media but dark orange in strong acidic environments. Such behavior enables it to work as a fluorescent pH sensor in solution states, and a chemosensor for detecting volatile organic compounds with high acidity and basicity in solid state. In addition, it can be used for fluorescent imaging in living cell and living organism. - Highlights: • Bright green fluorescence was observed in basic and neutral media. • Dark orange fluorescence was found in strong acidic environments. • Volatile organic compounds with high acidity and basicity could be detected. • Bioimaging in living cell and living organism was achieved successfully.

  5. Expression-Enhanced Fluorescent Proteins Based on Enhanced Green Fluorescent Protein for Super-resolution Microscopy.

    Science.gov (United States)

    Duwé, Sam; De Zitter, Elke; Gielen, Vincent; Moeyaert, Benjamien; Vandenberg, Wim; Grotjohann, Tim; Clays, Koen; Jakobs, Stefan; Van Meervelt, Luc; Dedecker, Peter

    2015-10-27

    "Smart fluorophores", such as reversibly switchable fluorescent proteins, are crucial for advanced fluorescence imaging. However, only a limited number of such labels is available, and many display reduced biological performance compared to more classical variants. We present the development of robustly photoswitchable variants of enhanced green fluorescent protein (EGFP), named rsGreens, that display up to 30-fold higher fluorescence in E. coli colonies grown at 37 °C and more than 4-fold higher fluorescence when expressed in HEK293T cells compared to their ancestor protein rsEGFP. This enhancement is not due to an intrinsic increase in the fluorescence brightness of the probes, but rather due to enhanced expression levels that allow many more probe molecules to be functional at any given time. We developed rsGreens displaying a range of photoswitching kinetics and show how these can be used for multimodal diffraction-unlimited fluorescence imaging such as pcSOFI and RESOLFT, achieving a spatial resolution of ∼70 nm. By determining the first ever crystal structures of a negative reversibly switchable FP derived from Aequorea victoria in both the "on"- and "off"-conformation we were able to confirm the presence of a cis-trans isomerization and provide further insights into the mechanisms underlying the photochromism. Our work demonstrates that genetically encoded "smart fluorophores" can be readily optimized for biological performance and provides a practical strategy for developing maturation- and stability-enhanced photochromic fluorescent proteins. PMID:26308583

  6. The bright optical flash from GRB 060117

    CERN Document Server

    Jel'inek, M; Kubánek, P; Hudec, R; Nekola, M; Grygar, J; Castro-Tirado, A J; Gorosabel, J; Hrabovsk'y, M; Mandat, D; Nosek, D; Palatka, M; Pandey, S B; Pech, M; Schovanek, P; De Postigo, A U; Vítek, S; Jel\\'inek, Martin; Prouza, Michael; Kub\\'anek, Petr; Hudec, Ren\\'e; Nekola, Martin; R}\\'idk\\'y, Jan {; Grygar, Ji{r}\\'i; Castro-Tirado, Alberto J.; Gorosabel, Javier; Hrabovsk\\'y, Miroslav; Mand\\'at, Du{s}an; Nosek, Dalibor; Palatka, Miroslav; Pandey, Shashi B.; Pech, Miroslav; Schov\\'anek, Petr; S}m\\'ida, Radom\\'ir {; Postigo, Antonio de Ugarte; V\\'itek, Stanislav

    2006-01-01

    We present a discovery and observation of an extraordinarily bright prompt optical emission of the GRB 060117 obtained by a wide-field camera atop the robotic telescope FRAM of the Pierre Auger Observatory from 2 to 10 minutes after the GRB. We found rapid average temporal flux decay of alpha = -1.7 +- 0.1 and a peak brightness R = 10.1 mag. Later observations by other instruments set a strong limit on the optical and radio transient fluxes, unveiling an unexpectedly rapid further decay. We present an interpretation featuring a relatively steep electron-distribution parameter p ~ 3.0 and providing a straightforward solution for the overall fast decay of this optical transient as a transition between reverse and forward shock.

  7. An ultra-bright atom laser

    International Nuclear Information System (INIS)

    We present a novel, ultra-bright atom laser and an ultra-cold thermal atom beam. Using rf-radiation we strongly couple the magnetic hyperfine levels of 87Rb atoms in a trapped Bose–Einstein condensate. The resulting time-dependent adiabatic potential forms a trap, which at low rf-frequencies opens just below the condensate and thus allows an extremely bright well-collimated atom laser beam to emerge. As opposed to traditional atom lasers based on weak coupling of the magnetic hyperfine levels, this technique allows us to outcouple atoms at an arbitrarily large rate. We achieve a flux of 4×107 atom s-1, a seven fold increase compared to the brightest atom lasers to date. Furthermore, we demonstrate by two orders of magnitude the coldest thermal atom beam (200 nK). (paper)

  8. Quantum Bright Soliton in a Disorder Potential

    Science.gov (United States)

    Sacha, K.; Delande, D.; Zakrzewski, J.

    2009-11-01

    At very low temperature, a quasi-one-dimensional ensemble of atoms with attractive interactions tend to form a bright soliton. When exposed to a sufficiently weak external potential, the shape of the soliton is not modified, but its external motion is affected. We develop in detail the Bogoliubov approach for the problem, treating, in a non-perturbative way, the motion of the center of mass of the soliton. Quantization of this motion allows us to discuss its long time properties. In particular, in the presence of a disordered potential, the quantum motion of the center of mass of a bright soliton may exhibit Anderson localization, on a localization length which may be much larger than the soliton size and could be observed experimentally.

  9. Contrasting effects of elevated carbon dioxide concentration and temperature on Rubisco activity, chlorophyll fluorescence, needle ultrastructure and secondary metabolites in conifer seedlings

    International Nuclear Information System (INIS)

    For 50 days, in an ambient or twice ambient carbon dioxide concentration, Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies L.) seedlings were grown. The temperature during the night was either 19 Celsius (C) or 23 C, while the night temperature was 12 C or 16 C. The results showed that elevated temperature increased above ground dry mass of both species, while the higher carbon dioxide concentration only slightly affected the growth parameters measured. The combined elevated carbon dioxide concentration (EC) and elevated temperature (ET) treatment produced the greatest biomass accumulation of all the treatments. Thylakoid swelling and increased numbers of plastoglobuli were observed in Scots pine needles under the EC treatment. Rubisco protein or nitrogen (N) concentration of needles were not much affected by the EC treatment, but the ET had a significant effect on N-containing compounds and enhanced N allocation from one-year-old needles. Total phenolics had a lesser response to EC and ET than terpenoids. EC generally reduced terpene concentrations, while ET increased them. The authors indicated that there could be an association between increased terpenoid concentrations in response to ET and thermotolerance to photosynthesis. Total phenolic concentrations in Norway spruce needles decreased as a result of EC, which might be due to increased growth. The results observed led the authors to conclude that the elevated carbon dioxide concentrations effects on the parameters studied were small for seedlings of both species, in comparison with the effects of elevated temperature. 62 refs., 7 tabs., 2 figs

  10. Contrasting effects of elevated carbon dioxide concentration and temperature on Rubisco activity, chlorophyll fluorescence, needle ultrastructure and secondary metabolites in conifer seedlings

    Energy Technology Data Exchange (ETDEWEB)

    Sallas, L.; Utriainen, J. [Kuopio Univ. (Finland). Dept. of Ecology and Environmental Science; Luomala, E.-M. [Finnish Forest Research Inst., Suonenjoki (Finland). Suonenjoki Research Station; Kainulainen, P.; Holopainen, J.K. [Kuopio Univ. (Finland). Dept. of Ecology and Environmental Science; Agricultural Research Center of Finland, Jokioinen (Finland). Plant Protection

    2003-02-01

    For 50 days, in an ambient or twice ambient carbon dioxide concentration, Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies L.) seedlings were grown. The temperature during the night was either 19 Celsius (C) or 23 C, while the night temperature was 12 C or 16 C. The results showed that elevated temperature increased above ground dry mass of both species, while the higher carbon dioxide concentration only slightly affected the growth parameters measured. The combined elevated carbon dioxide concentration (EC) and elevated temperature (ET) treatment produced the greatest biomass accumulation of all the treatments. Thylakoid swelling and increased numbers of plastoglobuli were observed in Scots pine needles under the EC treatment. Rubisco protein or nitrogen (N) concentration of needles were not much affected by the EC treatment, but the ET had a significant effect on N-containing compounds and enhanced N allocation from one-year-old needles. Total phenolics had a lesser response to EC and ET than terpenoids. EC generally reduced terpene concentrations, while ET increased them. The authors indicated that there could be an association between increased terpenoid concentrations in response to ET and thermotolerance to photosynthesis. Total phenolic concentrations in Norway spruce needles decreased as a result of EC, which might be due to increased growth. The results observed led the authors to conclude that the elevated carbon dioxide concentrations effects on the parameters studied were small for seedlings of both species, in comparison with the effects of elevated temperature. 62 refs., 7 tabs., 2 figs.

  11. Relationships between brightness of nighttime lights and population density

    Science.gov (United States)

    Naizhuo, Z.

    2012-12-01

    Brightness of nighttime lights has been proven to be a good proxy for socioeconomic and demographic statistics. Moreover, the satellite nighttime lights data have been used to spatially disaggregate amounts of gross domestic product (GDP), fossil fuel carbon dioxide emission, and electric power consumption (Ghosh et al., 2010; Oda and Maksyutov, 2011; Zhao et al., 2012). Spatial disaggregations were performed in these previous studies based on assumed linear relationships between digital number (DN) value of pixels in the nighttime light images and socioeconomic data. However, reliability of the linear relationships was never tested due to lack of relative high-spatial-resolution (equal to or finer than 1 km × 1 km) statistical data. With the similar assumption that brightness linearly correlates to population, Bharti et al. (2011) used nighttime light data as a proxy for population density and then developed a model about seasonal fluctuations of measles in West Africa. The Oak Ridge National Laboratory used sub-national census population data and high spatial resolution remotely-sensed-images to produce LandScan population raster datasets. The LandScan population datasets have 1 km × 1 km spatial resolution which is consistent with the spatial resolution of the nighttime light images. Therefore, in this study I selected 2008 LandScan population data as baseline reference data and the contiguous United State as study area. Relationships between DN value of pixels in the 2008 Defense Meteorological Satellite Program's Operational Linescan System (DMSP-OLS) stable light image and population density were established. Results showed that an exponential function can more accurately reflect the relationship between luminosity and population density than a linear function. Additionally, a certain number of saturated pixels with DN value of 63 exist in urban core areas. If directly using the exponential function to estimate the population density for the whole brightly

  12. Modular Zero Energy. BrightBuilt Home

    Energy Technology Data Exchange (ETDEWEB)

    Aldrich, Robb [Steven Winter Associates, Inc., Norwalk, CT (United States); Butterfield, Karla [Steven Winter Associates, Inc., Norwalk, CT (United States)

    2016-03-01

    With funding from the Building America Program, part of the U.S. Department of Energy Building Technologies Office, the Consortium for Advanced Residential Buildings (CARB) worked with BrightBuilt Home (BBH) to evaluate and optimize building systems. CARB’s work focused on a home built by Black Bros. Builders in Lincolnville, Maine (International Energy Conservation Code Climate Zone 6). As with most BBH projects to date, modular boxes were built by Keiser Homes in Oxford, Maine.

  13. Spectral Characterization of Bright Materials on Vesta

    Science.gov (United States)

    Capaccioni, Fabrizio; DeSanctis, M. C.; Ammannito, E.; Li, Jian-Yang; Longobardo, A.; Mittlefehldt, David W.; Palomba, E.; Pieters, C. M.; Schroeder, S. E.; Tosi, F.; Hiesinger, H.; Blewett, D. T.; Russell, C. T.; Raymond, C. A.

    2012-01-01

    The surface of Vesta, as observed by the camera and imaging spectrometer onboard the Dawn spacecraft, displays large surface diversity in terms of its geology and mineralogy with noticeably dark and bright areas on the surface often associated with various geological features and showing remarkably different forms. Here we report our initial attempt to spectrally characterize the areas that are distinctively brighter than their surroundings.

  14. Surface Brightness Fluctuations as Stellar Population Indicators

    OpenAIRE

    Blakeslee, John P

    2009-01-01

    Surface Brightness Fluctuations (SBF) can provide useful information about the unresolved stellar content of early-type galaxies and spiral bulges. The absolute SBF magnitude Mbar in a given passband depends on the properties of the stellar population and can be predicted by population synthesis models. SBF measurements in different bandpasses are sensitive to different evolutionary stages within the galaxy stellar population. Near-IR SBF magnitudes are sensitive to the evolution of stars wit...

  15. Bright vortex solitons in Bose Condensates

    OpenAIRE

    Adhikari, Sadhan K.

    2003-01-01

    We suggest the possibility of observing and studying bright vortex solitons in attractive Bose-Einstein condensates in three dimensions with a radial trap. Such systems lie on the verge of critical stability and we discuss the conditions of their stability. We study the interaction between two such solitons. Unlike the text-book solitons in one dimension, the interaction between two radially trapped and axially free three-dimensional solitons is inelastic in nature and involves exchange of pa...

  16. Bright Solitary Waves in Malignant Gliomas

    OpenAIRE

    Pérez-García, Víctor M.; Calvo, Gabriel F.; Belmonte-Beitia, Juan; Diego, D.; Pérez-Romasanta, Luis

    2011-01-01

    We put forward a nonlinear wave model describing the fundamental physio-pathologic features of an aggressive type of brain tumors: glioblastomas. Our model accounts for the invasion of normal tissue by a proliferating and propagating rim of active glioma cancer cells in the tumor boundary and the subsequent formation of a necrotic core. By resorting to numerical simulations, phase space analysis and exact solutions, we prove that bright solitary tumor waves develop in such systems.

  17. Origin of bright flares in SFXTs

    CERN Document Server

    Postnov, K; Sidoli, L; Paizis, A

    2014-01-01

    In the settling accretion theory, which is applicable to quasi-spherical accreting slowly rotating magnetized neutron stars with X-ray luminosity $L_x\\lesssim 4\\times 10^{36}$~erg/s, bright X-ray flares ($\\sim 10^{38}-10^{40}$~ergs) observed in supergiant fast X-ray transients (SFXT) may be produced by sporadic capture of magnetized stellar-wind plasma from the early-type supergiant. At sufficiently low steady accretion rates ($\\lesssim 10^{15}$~g/s) through the shell around the neutron star magnetosphere at the settling accretion stage, magnetic reconnection can temporarily enhance the magnetospheric plasma entry rate, resulting in copious production of X-ray photons, strong Compton cooling, and ultimately in unstable accretion of the entire shell. A bright flare develops on the free-fall time scale in the shell, $R_B^{3/2}/\\sqrt{GM}\\sim 10^3-10^4$~s ($R_B$ is the classical Bondi capture radius), and the typical energy released in an SFXT bright flare corresponds to the mass of the shell.

  18. On the origin of facular brightness

    CERN Document Server

    Kostik, R

    2016-01-01

    This paper studies the dependence of the CaIIH line core brightness on the strength and inclination of photospheric magnetic field, and on the parameters of convective and wave motions in a facular region at the solar disc center. We use three simultaneous datasets obtained at the German Vacuum Tower Telescope (Observatorio del Teide, Tenerife): (1) spectra of BaII 4554 A line registered with the instrument TESOS to measure the variations of intensity and velocity through the photosphere up to the temperature minimum; (2) spectropolarimetric data in FeI 1.56 $\\mu$m lines (registered with the instrument TIP II) to measure photospheric magnetic fields; (3) filtergrams in CaIIH that give information about brightness fluctuations in the chromosphere. The results show that the CaIIH brightness in the facula strongly depends on the power of waves with periods in the 5-min range, that propagate upwards, and also on the phase shift between velocity oscillations at the bottom photosphere and around the temperature min...

  19. Search for bright stars with infrared excess

    International Nuclear Information System (INIS)

    Bright stars, stars with visual magnitude smaller than 6.5, can be studied using small telescope. In general, if stars are assumed as black body radiator, then the color in infrared (IR) region is usually equal to zero. Infrared data from IRAS observations at 12 and 25μm (micron) with good flux quality are used to search for bright stars (from Bright Stars Catalogues) with infrared excess. In magnitude scale, stars with IR excess is defined as stars with IR color m12−m25>0; where m12−m25 = −2.5log(F12/F25)+1.56, where F12 and F25 are flux density in Jansky at 12 and 25μm, respectively. Stars with similar spectral type are expected to have similar color. The existence of infrared excess in the same spectral type indicates the existence of circum-stellar dust, the origin of which is probably due to the remnant of pre main-sequence evolution during star formation or post AGB evolution or due to physical process such as the rotation of those stars

  20. Bright-field Nanoscopy: Visualizing Nano-structures with Localized Optical Contrast Using a Conventional Microscope

    CERN Document Server

    Suran, Swathi; Raghavan, Srinivasan; Varma, Manoj M

    2015-01-01

    Most methods for optical visualization beyond the diffraction limit rely on fluorescence emission by molecular tags. Here, we report a method for visualization of nanostructures down to a few nanometers using a conventional bright-field microscope without requiring additional molecular tags such as fluorophores. The technique, Bright-field Nanoscopy, is based on the strong thickness dependent color of ultra-thin germanium on an optically thick gold film. We demonstrate the visualization of grain boundaries in chemical vapour deposited single layer graphene and the detection of single 40 nm Ag nanoparticles. We estimate a size detection limit of about 2 nm using this technique. In addition to visualizing nano-structures, this technique can be used to probe fluid phenomena at the nanoscale, such as transport through 2D membranes. We estimated the water transport rate through a 1 nm thick polymer film using this technique, as an illustration. Further, the technique can also be extended to study the transport of ...

  1. The surface brightness of spiral galaxies: Pt. 4

    International Nuclear Information System (INIS)

    Using measurements from IRAS correlations are found between optical surface brightness and both infrared-to-optical flux ratio and infrared colour temperature, in the sense that galaxies with high surface brightness have higher FIR emission and higher temperatures. (author)

  2. Fluorescence detection: SPIE volume 743

    International Nuclear Information System (INIS)

    This book contains proceedings arranged into four sessions. They are: Fluorescence spectroscopic techniques; Fluorescence in analysis and materials characterization; Fluorescence in medicine and biochemistry; and Fluorescence in criminalistics

  3. Fluorescence detection: SPIE volume 743

    Energy Technology Data Exchange (ETDEWEB)

    Menzel, E.R.

    1987-01-01

    This book contains proceedings arranged into four sessions. They are: Fluorescence spectroscopic techniques; Fluorescence in analysis and materials characterization; Fluorescence in medicine and biochemistry; and Fluorescence in criminalistics.

  4. Star formation and the surface brightness of spiral galaxies

    International Nuclear Information System (INIS)

    The (blue) surface brightness of spiral galaxies is significantly correlated with their Hα linewidth. This can be most plausibly interpreted as a correlation of surface brightness with star formation rate. There is also a significant difference in surface brightness between galaxies forming stars in a grand design spiral pattern and those with floc star formation regions. (author)

  5. Germanium-doped carbon dots as a new type of fluorescent probe for visualizing the dynamic invasions of mercury(ii) ions into cancer cells

    Science.gov (United States)

    Yuan, Yun Huan; Li, Rong Sheng; Wang, Qiang; Wu, Zhu Lian; Wang, Jian; Liu, Hui; Huang, Cheng Zhi

    2015-10-01

    Carbon dots doped with germanium (GeCDs) were firstly prepared by a new simple 15 min carbonation synthesis route, exhibiting excitation-independent photoluminescence (PL), which could avoid autofluorescence in bioimaging applications. The as-prepared GeCDs have low cell toxicity, good biocompatibility, high intracellular delivery efficiency, stability and could be applied for detection of mercury(ii) ions with excellent selectivity in complicated medium. It is to be noted that the as-prepared GeCDs used as a new type of probe for visualization of dynamic invasions of mercury(ii) ions into Hep-2 cells display greatly different properties from most of the previously reported CDs which are regularly responsive to iron ions. All the results suggest that the GeCDs can be employed for visualization and monitoring of the significant physiological changes of living cells induced by Hg2+.Carbon dots doped with germanium (GeCDs) were firstly prepared by a new simple 15 min carbonation synthesis route, exhibiting excitation-independent photoluminescence (PL), which could avoid autofluorescence in bioimaging applications. The as-prepared GeCDs have low cell toxicity, good biocompatibility, high intracellular delivery efficiency, stability and could be applied for detection of mercury(ii) ions with excellent selectivity in complicated medium. It is to be noted that the as-prepared GeCDs used as a new type of probe for visualization of dynamic invasions of mercury(ii) ions into Hep-2 cells display greatly different properties from most of the previously reported CDs which are regularly responsive to iron ions. All the results suggest that the GeCDs can be employed for visualization and monitoring of the significant physiological changes of living cells induced by Hg2+. Electronic supplementary information (ESI) available: Experimental section and additional figures (Fig. S1-15). See DOI: 10.1039/c5nr05326a

  6. Controlling excitons. Concepts for phosphorescent organic LEDs at high brightness

    Energy Technology Data Exchange (ETDEWEB)

    Reineke, Sebastian

    2009-11-15

    This work focusses on the high brightness performance of phosphorescent organic light-emitting diodes (OLEDs). The use of phosphorescent emitter molecules in OLEDs is essential to realize internal electron-photon conversion efficiencies of 100 %. However, due to their molecular nature, the excited triplet states have orders of magnitude longer time constants compared to their fluorescent counterparts which, in turn, strongly increases the probability of bimolecular annihilation. As a consequence, the efficiencies of phosphorescent OLEDs decline at high brightness - an effect known as efficiency roll-off, for which it has been shown to be dominated by triplet-triplet annihilation (TTA). In this work, TTA of the archetype phosphorescent emitter Ir(ppy){sub 3} is investigated in time-resolved photoluminescence experiments. For the widely used mixed system CBP:Ir(ppy){sub 3}, host-guest TTA - an additional unwanted TTA channel - is experimentally observed at high excitation levels. By using matrix materials with higher triplet energies, this effect is efficiently suppressed, however further studies show that the efficiency roll-off of Ir(ppy)3 is much more pronounced than predicted by a model based on Foerster-type energy transfer, which marks the intrinsic limit for TTA. These results suggest that the emitter molecules show a strong tendency to form aggregates in the mixed film as the origin for enhanced TTA. Transmission electron microscopy images of Ir(ppy){sub 3} doped mixed films give direct proof of emitter aggregates. Based on these results, two concepts are developed that improve the high brightness performance of OLEDs. In a first approach, thin intrinsic matrix interlayers are incorporated in the emission layer leading to a one-dimensional exciton confinement that suppresses exciton migration and, consequently, TTA. The second concept reduces the efficiency roll-off by using an emitter molecule with slightly different chemical structure, i.e. Ir(ppy){sub 2

  7. CN and CH Bandstrengths in Bright Globular Cluster Red Giants

    Science.gov (United States)

    Martell, Sarah L.; Smith, G. H.

    2006-12-01

    We present preliminary results from a survey of CN and CH bandstrengths in bright red giant stars (MV -1.5) in Galactic globular clusters. Our cluster sample spans a wide metallicity range, from M92 ([Fe/H]=-2.28) to M71 ([Fe/H]=-0.73). The data were all taken using the Shane 120-inch telescope and the Kast spectrograph at Lick Observatory; the homogeneity of the sample makes it ideal for a comparative study of carbon depletion (and therefore deep mixing rate) as a function of stellar metallicity. Thus far we have measured molecular bandstrength indices for CH and CN, as well as indices for Ca and Mg lines; the task of converting the index measurements to carbon and nitrogen abundances will require comparisons with synthetic spectra. The molecular CN index behaves as expected from a study of the literature: within individual clusters, it varies significantly from star to star. The data also allow us to examine the dependence of the Ca and Mg indices on cluster metallicity at a given MV. The index MHK shows clear sensitivity to [Fe/H] across the full metallicity range of our sample. A similar study is also in progress involving analogous stars in the open clusters NGC 188, NGC 2158, NGC 6791, and NGC 7789 (-0.3 < [Fe/H] < +0.3).

  8. In-vivo Fluorescence Imaging in the NIR-II with Long Circulating Carbon Nanotubes Capable of Ultra-High Tumor Uptake

    OpenAIRE

    Robinson, Joshua T.; Hong, Guosong; Liang, Yongye; Zhang, Bo; Yaghi, Omar K.; Dai, Hongjie

    2012-01-01

    Cancer imaging requires selective high accumulation of contrast agents in the tumor region and correspondingly low uptake in healthy tissues. Here, by making use of a novel synthetic polymer to solubilize single-walled carbon nanotubes (SWNTs), we prepared a well-functionalized SWNT formulation with long blood circulation (half life ~ 30 h) in vivo to achieve ultra-high accumulation of ~30% injected dose (ID)/gram in 4T1 murine breast tumors in Balb/c mice. Functionalization dependent blood c...

  9. Monitoring of bright blazars with MAGIC telescope

    OpenAIRE

    Hsu, C. C.; Satalecka, K.; Thom, M; Backes, M.; Bernardini, E.; Bonnoli, G.; Galante, N.; Goebel, F; Lindfors, E.; Majumdar, P.; Stamerra, A.; Wagner, R. M.

    2009-01-01

    Blazars, a class of Active Galactic Nuclei (AGN) characterized by a close orientation of their relativistic outflows (jets) towards the line of sight, are a well established extragalactic TeV $\\gamma$-ray emitters. Since 2006, three nearby and TeV bright blazars, Markarian (Mrk) 421, Mrk 501 and 1ES 1959+650, are regularly observed by the MAGIC telescope with single exposures of 30 to 60 minutes. The sensitivity of MAGIC allows to establish a flux level of 30% of the Crab flux for each such o...

  10. The Bright Quasar 3C 273

    OpenAIRE

    Courvoisier, Thierry J. -L.

    1998-01-01

    We review the observed properties of the bright quasar 3C~273 and discuss the implications of these observations for the emission processes and in view of gaining a more global understanding of the object. Continuum and line emission are discussed. The emission from the radio domain to gamma rays are reviewed. Emphasis is given to variability studies across the spectrum as a means to gain some understanding on the relationships between the emission components. 3C~273 has a small scale jet and...

  11. Quantum bright soliton in a disorder potential

    OpenAIRE

    Sacha, K.; Delande, D; Zakrzewski, J.

    2009-01-01

    At very low temperature, a quasi-one-dimensional ensemble of atoms with attractive interactions tend to form a bright soliton. When exposed to a sufficiently weak external potential, the shape of the soliton is not modified, but its external motion is affected. We develop in detail the Bogoliubov approach for the problem, treating, in a non-perturbative way, the motion of the center of mass of the soliton. Quantization of this motion allows us to discuss its long time properties. In particula...

  12. Extremely High Brightness from Polymer-Encapsulated Quantum Dots for Two-photon Cellular and Deep-tissue Imaging

    OpenAIRE

    Fan, Yanyan; Liu, Helin; Han, Rongcheng; Huang, Lu; Shi, Hao; Sha, Yinlin; Jiang, Yuqiang

    2015-01-01

    Materials possessing high two photon absorption (TPA) are highly desirable for a range of fields, such as three-dimensional data storage, TP microscopy (TPM) and photodynamic therapy (PDT). Specifically, for TPM, high TP excitation (TPE) brightness (σ × ϕ, where σ is TPA cross-sections and ϕ is fluorescence quantum yield), excellent photostability and minimal cytotoxicity are highly desirable. However, when TPA materials are transferred to aqueous media through molecule engineering or nanopar...

  13. Selection effects in the bivariate brightness distribution for spiral galaxies

    International Nuclear Information System (INIS)

    The joint distribution of total luminosity and characteristic surface brightness (the bivariate brightness distribution) is investigated for a complete sample of spiral galaxies in the Virgo cluster. The influence of selection and physical limits of various kinds on the apparent distribution are detailed. While the distribution of surface brightness for bright galaxies may be genuinely fairly narrow, faint galaxies exist right across the (quite small) range of accessible surface brightnesses so no statement can be made about the true extent of the distribution. The lack of high surface brightness bright galaxies in the Virgo sample relative to an overall RC2 sample (mostly field galaxies) supports the contention that the star-formation rate is reduced in the inner region of the cluster for environmental reasons. (author)

  14. Trace fluorescent labeling for protein crystallization

    Energy Technology Data Exchange (ETDEWEB)

    Pusey, Marc, E-mail: marc.pusey@ixpressgenes.com; Barcena, Jorge; Morris, Michelle; Singhal, Anuj; Yuan, Qunying; Ng, Joseph [iXpressGenes Inc., 601 Genome Way, Huntsville, AL 35810 (United States)

    2015-06-27

    The presence of a covalently bound fluorescent probe at a concentration of <0.5% does not affect the outcome of macromolecule crystallization screening experiments. Additionally, the fluorescence can be used to determine new, not immediately apparent, lead crystallization conditions. Fluorescence can be a powerful tool to aid in the crystallization of proteins. In the trace-labeling approach, the protein is covalently derivatized with a high-quantum-yield visible-wavelength fluorescent probe. The final probe concentration typically labels ≤0.20% of the protein molecules, which has been shown to not affect the crystal nucleation or diffraction quality. The labeled protein is then used in a plate-screening experiment in the usual manner. As the most densely packed state of the protein is the crystalline form, then crystals show as the brightest objects in the well under fluorescent illumination. A study has been carried out on the effects of trace fluorescent labeling on the screening results obtained compared with nonlabeled protein, and it was found that considering the stochastic nature of the crystal nucleation process the presence of the probe did not affect the outcomes obtained. Other effects are realised when using fluorescence. Crystals are clearly seen even when buried in precipitate. This approach also finds ‘hidden’ leads, in the form of bright spots, with ∼30% of the leads found being optimized to crystals in a single-pass optimization trial. The use of visible fluorescence also enables the selection of colors that bypass interfering substances, and the screening materials do not have to be UV-transparent.

  15. Coronal bright points associated with minifilament eruptions

    International Nuclear Information System (INIS)

    Coronal bright points (CBPs) are small-scale, long-lived coronal brightenings that always correspond to photospheric network magnetic features of opposite polarity. In this paper, we subjectively adopt 30 CBPs in a coronal hole to study their eruptive behavior using data from the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory. About one-quarter to one-third of the CBPs in the coronal hole go through one or more minifilament eruption(s) (MFE(s)) throughout their lifetimes. The MFEs occur in temporal association with the brightness maxima of CBPs and possibly result from the convergence and cancellation of underlying magnetic dipoles. Two examples of CBPs with MFEs are analyzed in detail, where minifilaments appear as dark features of a cool channel that divide the CBPs along the neutral lines of the dipoles beneath. The MFEs show the typical rising movements of filaments and mass ejections with brightenings at CBPs, similar to large-scale filament eruptions. Via differential emission measure analysis, it is found that CBPs are heated dramatically by their MFEs and the ejected plasmas in the MFEs have average temperatures close to the pre-eruption BP plasmas and electron densities typically near 109 cm–3. These new observational results indicate that CBPs are more complex in dynamical evolution and magnetic structure than previously thought.

  16. At Bright Band Inside Victoria Crater

    Science.gov (United States)

    2007-01-01

    A layer of light-toned rock exposed inside Victoria Crater in the Meridiani Planum region of Mars appears to mark where the surface was at the time, many millions of years ago, when an impact excavated the crater. NASA's Mars Exploration Rover Opportunity drove to this bright band as the science team's first destination for the rover during investigations inside the crater. Opportunity's left front hazard-identification camera took this image just after the rover finished a drive of 2.25 meters (7 feet, 5 inches) during the rover's 1,305th Martian day, or sol, (Sept. 25, 2007). The rocks beneath the rover and its extended robotic arm are part of the bright band. Victoria Crater has a scalloped shape of alternating alcoves and promontories around the crater's circumference. Opportunity descended into the crater two weeks earlier, within an alcove called 'Duck Bay.' Counterclockwise around the rim, just to the right of the arm in this image, is a promontory called 'Cabo Frio.'

  17. A novel fluorescent assay for sucrose transporters

    Directory of Open Access Journals (Sweden)

    Gora Peter J

    2012-04-01

    Full Text Available Abstract Background We have developed a novel assay based on the ability of type I sucrose uptake transporters (SUTs to transport the fluorescent coumarin β-glucoside, esculin. Budding yeast (Saccharomyces cerevisiae is routinely used for the heterologous expression of SUTs and does not take up esculin. Results When type I sucrose transporters StSUT1 from potato or AtSUC2 from Arabidopsis were expressed in yeast, the cells were able to take up esculin and became brightly fluorescent. We tested a variety of incubation times, esculin concentrations, and buffer pH values and found that for these transporters, a 1 hr incubation at 0.1 to 1 mM esculin at pH 4.0 produced fluorescent cells that were easily distinguished from vector controls. Esculin uptake was assayed by several methods including fluorescence microscopy, spectrofluorometry and fluorescence-activiated cell sorting (FACS. Expression of the type II sucrose transporter OsSUT1 from rice did not result in increased esculin uptake under any conditions tested. Results were reproduced successfully in two distinct yeast strains, SEY6210 (an invertase mutant and BY4742. Conclusions The esculin uptake assay is rapid and sensitive and should be generally useful for preliminary tests of sucrose transporter function by heterologous expression in yeast. This assay is also suitable for selection of yeast showing esculin uptake activity using FACS.

  18. FAA Fluorescent Penetrant Laboratory Inspections

    Energy Technology Data Exchange (ETDEWEB)

    WINDES,CONNOR L.; MOORE,DAVID G.

    2000-08-02

    The Federal Aviation Administration Airworthiness Assurance NDI Validation Center currently assesses the capability of various non-destructive inspection (NDI) methods used for analyzing aircraft components. The focus of one such exercise is to evaluate the sensitivity of fluorescent liquid penetrant inspection. A baseline procedure using the water-washable fluorescent penetrant method defines a foundation for comparing the brightness of low cycle fatigue cracks in titanium test panels. The analysis of deviations in the baseline procedure will determine an acceptable range of operation for the steps in the inspection process. The data also gives insight into the depth of each crack and which step(s) of the inspection process most affect penetrant sensitivities. A set of six low cycle fatigue cracks produced in 6.35-mm thick Ti-6Al-4V specimens was used to conduct the experiments to produce sensitivity data. The results will document the consistency of the crack readings and compare previous experiments to find the best parameters for water-washable penetrant.

  19. Molecularly Tunable Fluorescent Quantum Defects.

    Science.gov (United States)

    Kwon, Hyejin; Furmanchuk, Al'ona; Kim, Mijin; Meany, Brendan; Guo, Yong; Schatz, George C; Wang, YuHuang

    2016-06-01

    We describe the chemical creation of molecularly tunable fluorescent quantum defects in semiconducting carbon nanotubes through covalently bonded surface functional groups that are themselves nonemitting. By variation of the surface functional groups, the same carbon nanotube crystal is chemically converted to create more than 30 distinct fluorescent nanostructures with unique near-infrared photoluminescence that is molecularly specific, systematically tunable, and significantly brighter than that of the parent semiconductor. This novel exciton-tailoring chemistry readily occurs in aqueous solution and creates functional defects on the sp(2) carbon lattice with highly predictable C-C bonding from virtually any iodine-containing hydrocarbon precursor. Our new ability to control nanostructure excitons through a single surface functional group opens up exciting possibilities for postsynthesis chemical engineering of carbon nanomaterials and suggests that the rational design and creation of a large variety of molecularly tunable quantum emitters-for applications ranging from in vivo bioimaging and chemical sensing to room-temperature single-photon sources-can now be anticipated. PMID:27159413

  20. Real Time Monitoring of Dissolved Organic Carbon Concentration and Disinfection By-Product Formation Potential in a Surface Water Treatment Plant with Simulaneous UV-VIS Absorbance and Fluorescence Excitation-Emission Mapping

    Science.gov (United States)

    Gilmore, A. M.

    2015-12-01

    This study describes a method based on simultaneous absorbance and fluorescence excitation-emission mapping for rapidly and accurately monitoring dissolved organic carbon concentration and disinfection by-product formation potential for surface water sourced drinking water treatment. The method enables real-time monitoring of the Dissolved Organic Carbon (DOC), absorbance at 254 nm (UVA), the Specific UV Absorbance (SUVA) as well as the Simulated Distribution System Trihalomethane (THM) Formation Potential (SDS-THMFP) for the source and treated water among other component parameters. The method primarily involves Parallel Factor Analysis (PARAFAC) decomposition of the high and lower molecular weight humic and fulvic organic component concentrations. The DOC calibration method involves calculating a single slope factor (with the intercept fixed at 0 mg/l) by linear regression for the UVA divided by the ratio of the high and low molecular weight component concentrations. This method thus corrects for the changes in the molecular weight component composition as a function of the source water composition and coagulation treatment effects. The SDS-THMFP calibration involves a multiple linear regression of the DOC, organic component ratio, chlorine residual, pH and alkalinity. Both the DOC and SDS-THMFP correlations over a period of 18 months exhibited adjusted correlation coefficients with r2 > 0.969. The parameters can be reported as a function of compliance rules associated with required % removals of DOC (as a function of alkalinity) and predicted maximum contaminant levels (MCL) of THMs. The single instrument method, which is compatible with continuous flow monitoring or grab sampling, provides a rapid (2-3 minute) and precise indicator of drinking water disinfectant treatability without the need for separate UV photometric and DOC meter measurements or independent THM determinations.

  1. New Distant Comet Headed for Bright Encounter

    Science.gov (United States)

    1995-08-01

    How Impressive Will Comet Hale-Bopp Become in 1997 ? A very unusual comet was discovered last month, on its way from the outer reaches of the solar system towards the Sun. Although it is still situated beyond the orbit of Jupiter, it is so bright that it can be observed in even small telescopes. It has been named `Hale-Bopp' after the discoverers and is already of great interest to cometary astronomers. No less than seven telescopes have been used at the ESO La Silla observatory for the first observations of the new object. Together with data gathered at other sites, their aim is to elucidate the nature of this comet and also to determine whether there is reason to hope that it will become a bright and beautiful object in the sky from late 1996 and well into 1997. Further observations are now being planned at ESO and elsewhere to monitor closely the behaviour of this celestial visitor during the coming months. Discovery circumstances The comet was discovered on 23 July 1995, nearly simultaneously by two American amateur astronomers, Alan Hale of Cloudcroft (New Mexico) and Thomas Bopp of Glendale (Arizona). Although the chronology is slightly uncertain, it appears that Hale first saw it some 10 - 20 minutes before Bopp, at 06:10 - 06:15 UT on that day. In any case, he informed the IAU Central Bureau for Astronomical Telegrams (CBAT) in Cambridge (Massachussetts) about his discovery by email already at 06:50 UT, while Bopp's message was filed more than 2 hours later, after he had driven back to his home, 140 km from where he had been observing. Upon receipt of these messages, Brian Marsden at the CBAT assigned the designation `1995 O1' (indicating that it is the first comet found in the second half of July 1995). After further sightings had been made by other observers, and according to the venerable astronomical tradition, the new object was named after the discoverers. The magnitude, reported as 10.5 by Hale, is not unusual for a comet that is discovered within

  2. Interfacing click chemistry with automated oligonucleotide synthesis for the preparation of fluorescent DNA probes containing internal xanthene and cyanine dyes

    DEFF Research Database (Denmark)

    Astakhova, I Kira; Wengel, Jesper

    2013-01-01

    : Considerable Stokes shifts (40-110 nm), quenched fluorescence of single-stranded probes accompanied by up to 7.7-fold light-up effect of emission upon target DNA/RNA binding, remarkable sensitivity to single-nucleotide mismatches, generally high fluorescence brightness values (FB up to 26), and hence low limit...

  3. Trace amounts of poly-β-cyclodextrin wrapped carbon nanotubes for the microextraction of flavonoids in honey samples by capillary electrophoresis with light-emitting diode induced fluorescence detection.

    Science.gov (United States)

    Xu, Jing-Jing; An, Mingrui; Yang, Rui; Cao, Jun; Ye, Li-Hong; Peng, Li-Qing

    2016-07-01

    A novel dispersive micro-SPE method with trace poly-β-CD wrapped multiwalled carbon nanotubes as sorbents was applied to extract flavonoids in honey samples. The analytes were then determined by CE with LED-induced fluorescence detection. The influencing parameters, such as the sorbent concentration, extraction time, and eluent type, were properly optimized. The established method had the advantages of simplicity, low consumption of sorbent amount (0.009 mg) and organic solvent (100 μL), and high sensitivity, meeting the principle of green chemistry. Under the optimum conditions, the sorbents allowed the extraction and preconcentration of the flavonoids with enrichment factors in the range from 78 to 166. The recovery study performed at two different fortification levels provided an average recovery >91%. LODs for all the compounds ranged from 0.07 to 17.99 ng/mL. These results demonstrated that the proposed method could be used as a convenient and efficient extraction technique for analysis of flavonoids in different honey matrices. PMID:27060460

  4. Determination of trace amounts of hexavalent chromium in drinking waters by dispersive microsolid-phase extraction using modified multiwalled carbon nanotubes combined with total reflection X-ray fluorescence spectrometry

    Science.gov (United States)

    Bahadir, Z.; Bulut, V. N.; Hidalgo, M.; Soylak, M.; Marguí, E.

    2015-05-01

    A methodology based on the combination of dispersive microsolid-phase extraction (DMSPE) with total reflection X-ray fluorescence (TXRF) spectrometry is proposed for the determination of hexavalent chromium in drinking waters. Multiwalled carbon nanotubes (MWCNTs) modified with the anionic exchanger tricaprylmethylammonium chloride (Aliquat 336) were used as solid sorbents. After the sorption process of Cr(VI) on the modified MWCNTs, the aqueous sample was separated by centrifugation and the loaded MWCNTs were suspended using a small volume of an internal standard solution and analyzed directly by a benchtop TXRF spectrometer, without any elution step. Parameters affecting the extraction process (pH and volume of the aqueous sample, amount of MWCNTs, extraction time) and TXRF analysis (volume of internal standard, volume of deposited suspension on the reflector, drying mode, and instrumental parameters) have been carefully evaluated to test the real capability of the developed methodology for the determination of Cr(VI) at trace levels. Using the best analytical conditions, it was found that the minimum Cr(VI) content that can be detected in an aqueous solution was 3 μg L- 1. This value is almost 20 times lower than the maximum hexavalent chromium content permissible in drinking waters, according to the World Health Organization (WHO). Recoveries for spiked tap and mineral water samples were, in most cases, in the range of 101-108% which demonstrates the suitability of the TXRF methodology for monitoring Cr(VI) at trace levels in drinking water samples.

  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. PMID:23931503

  6. Brightness temperature for 166 radio sources

    Institute of Scientific and Technical Information of China (English)

    Jun-Hui Fan; Yong Huang; Yu-Hai Yuan; Jiang-He Yang; Yi Liu; Jun Tao; Ying Gao; Tong-Xu Hua; Rui-Guang Lin; Jiang-Shui Zhang; Jing-Yi Zhang; Yi-Ping Qin

    2009-01-01

    Using the database of the University of Michigan Radio Astronomy Observatory (UMRAO) at three radio frequencies (4.8, 8 and 14.5 GHz), we determined the short-term variability timescales for 166 radio sources. The timescales are 0.15d (2007+777) to 176.17d (0528-250) with an average timescale of △tobs=17.1±16.5d for the whole sample. The timescales are used to calculate the brightness temperatures, TB. The value of log TB is in the range of log TB = 10.47 to 19.06 K. In addition, we also estimated the boosting factor for the sources. The correlation between the polarization and the Doppler factor is also discussed.

  7. Modelling Solar and Stellar Brightness Variabilities

    Science.gov (United States)

    Yeo, K. L.; Shapiro, A. I.; Krivova, N. A.; Solanki, S. K.

    2016-04-01

    Total and spectral solar irradiance, TSI and SSI, have been measured from space since 1978. This is accompanied by the development of models aimed at replicating the observed variability by relating it to solar surface magnetism. Despite significant progress, there remains persisting controversy over the secular change and the wavelength-dependence of the variation with impact on our understanding of the Sun's influence on the Earth's climate. We highlight the recent progress in TSI and SSI modelling with SATIRE. Brightness variations have also been observed for Sun-like stars. Their analysis can profit from knowledge of the solar case and provide additional constraints for solar modelling. We discuss the recent effort to extend SATIRE to Sun-like stars.

  8. High brightness angled cavity quantum cascade lasers

    International Nuclear Information System (INIS)

    A quantum cascade laser (QCL) with an output power of 203 W is demonstrated in pulsed mode at 283 K with an angled cavity. The device has a ridge width of 300 μm, a cavity length of 5.8 mm, and a tilt angle of 12°. The back facet is high reflection coated, and the front facet is anti-reflection coated. The emitting wavelength is around 4.8 μm. In distinct contrast to a straight cavity broad area QCL, the lateral far field is single lobed with a divergence angle of only 3°. An ultrahigh brightness value of 156 MW cm−2 sr−1 is obtained, which marks the brightest QCL to date

  9. Considerations for high-brightness electron sources

    International Nuclear Information System (INIS)

    Particle accelerators are now used in many areas of physics research and in industrial and medical applications. New uses are being studied to address major societal needs in energy production, materials research, generation of intense beams of radiation at optical and suboptical wavelengths, treatment of various kinds of waste, and so on. Many of these modern applications require a high intensity beam at the desired energy, along with a very good beam quality in terms of the beam confinement, aiming, or focusing. Considerations for ion and electron accelerators are often different, but there are also many commonalties, and in fact, techniques derived for one should perhaps more often be considered for the other as well. We discuss some aspects of high-brightness electron sources here from that point of view. 6 refs

  10. High brightness angled cavity quantum cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Heydari, D.; Bai, Y.; Bandyopadhyay, N.; Slivken, S.; Razeghi, M., E-mail: razeghi@eecs.northwestern.edu [Center for Quantum Devices, Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, Illinois 60208 (United States)

    2015-03-02

    A quantum cascade laser (QCL) with an output power of 203 W is demonstrated in pulsed mode at 283 K with an angled cavity. The device has a ridge width of 300 μm, a cavity length of 5.8 mm, and a tilt angle of 12°. The back facet is high reflection coated, and the front facet is anti-reflection coated. The emitting wavelength is around 4.8 μm. In distinct contrast to a straight cavity broad area QCL, the lateral far field is single lobed with a divergence angle of only 3°. An ultrahigh brightness value of 156 MW cm{sup −2 }sr{sup −1} is obtained, which marks the brightest QCL to date.

  11. Dark Skies, Bright Kids Year 7

    Science.gov (United States)

    Bittle, Lauren E.; Johnson, Kelsey E.; Borish, H. Jacob; Burkhardt, Andrew; Firebaugh, Ariel; Hancock, Danielle; Rochford Hayes, Christian; Linden, Sean; Liss, Sandra; Matthews, Allison; Prager, Brian; Pryal, Matthew; Sokal, Kimberly R.; Troup, Nicholas William; Wenger, Trey

    2016-01-01

    We present updates from our seventh year of operation including new club content, continued assessments, and our fifth annual Star Party. Dark Skies, Bright Kids (DSBK) is an entirely volunteer-run outreach organization based out of the Department of Astronomy at the University of Virginia. Our core mission is to enhance elementary science education and literacy in Central Virginia through fun, hands-on activities that introduce basic Astronomy concepts. Our primary focus is hosting an 8-10 week after-school astronomy club at underserved elementary and middle schools. Each week, DSBK volunteers take the role of coaches to introduce astronomy-related concepts ranging from the Solar System to galaxies to astrobiology, and to lead students in interactive learning activities. Another hallmark of DSBK is hosting our Annual Central Virginia Star Party, a free event open to the community featuring star-gazing and planetarium shows.

  12. Brightness-equalized quantum dots: Engineering strategies derived from spectral trends

    Science.gov (United States)

    Smith, Andrew M.; Lim, Sung Jun

    2015-03-01

    Quantum dots are semiconductor nanocrystals that absorb and emit light at wavelengths tunable by the size of the crystal. Size-tuning provides access to a broad range of optical spectra, however it is fundamentally problematic for many applications because it leads to a large mismatch in absorption cross-section and fluorescence brightness across a series of colors. We have recently demonstrated engineering strategies to generate multicolor, extinction-matched, and brightness-matched quantum dots based on colloidal multi-domain core/shell structures. We use alloyed cores with composition-tunable bandgaps and finely adjust the domain size and electronic properties of the shell to precisely match both absorption cross-section and quantum yield. Using this strategy, it is possible to tune fluorescence wavelength, extinction, and quantum yield independently, vastly expanding the photophysical landscape of these materials. Moreover compared with conventional size-tuning strategies, this enables access to a wider spectral range with compact dimensions. The equalized optical properties translate from the ensemble level down to the single-molecule level, setting the stage for new possibilities in highly quantitative, multiplexed imaging in cells and tissue. However selection of appropriate structural parameters to generate specific optical properties is challenging without insight into the photophysics of these materials. Here we describe the evolution of the optical properties of alloyed cores during the shell growth process that provide new insights into general engineering strategies.

  13. Moon night sky brightness simulation for the Xinglong station

    International Nuclear Information System (INIS)

    Using a sky brightness monitor at the Xinglong station of National Astronomical Observatories, Chinese Academy of Sciences, we collected data from 22 dark clear nights and 90 moon nights. We first measured the sky brightness variation with time for dark nights and found a clear correlation between sky brightness and human activity. Then with a modified sky brightness model of moon nights and data from these nights, we derived the typical value for several important parameters in the model. With these results, we calculated the sky brightness distribution under a given moon condition for the Xinglong station. Furthermore, we simulated the sky brightness distribution of a moon night for a telescope with a 5° field of view (such as LAMOST). These simulations will be helpful for determining the limiting magnitude and exposure time, as well as planning the survey for LAMOST during moon nights

  14. Variability, Brightness Temperature, Superluminal Motion, Doppler Boosting, and Related Issues

    CERN Document Server

    Kellermann, K I

    2003-01-01

    We review the observations of rapid flux density variations in compact radio sources, and discuss the inverse Compton limit to the maximum brightness temperature of incoherent synchrotron sources in comparison with recent VLBA observations. The apparent agreement of the theoretical brightness temperature limit due to inverse Compton cooling and the brightness temperatures observed by early VLBI observations appears to have been fortuitous. VLBA observations have greatly improved the quality of the data, but many of the early issues remain unresolved.

  15. Annular bright and dark field imaging of soft materials

    International Nuclear Information System (INIS)

    Here polyethylene, as an example of an important soft material, was studied by STEM annular bright and dark field. The contrast as function of the probe size/shape and the detector collection angle are discussed. The results are compared to conventional bright field transmission electron microscopy, electron energy filtered imaging and energy dispersive spectroscopy mapping. Annular bright and dark field gave a higher contrast than conventional transmission and analytical mapping techniques

  16. Research on Brightness Measurement of Intense Electron Beam

    CERN Document Server

    Wang, Yuan; Zhang, Huang; Yang, GuoJun; Li, YiDing; Li, Jin

    2015-01-01

    The mostly research fasten on high emission density of injector to study electron beam's brightness in LIA. Using the injector(2MeV) was built to research brightness of multi-pulsed high current(KA) electron beam, and researchs three measurement method (the pepper-pot method, beam collimator without magnetic field, beam collimator with magnetic field method) to detect beam's brightness with time-resolved measurement system.

  17. Label-free characterization of carbonic anhydrase-novel inhibitor interactions using surface plasmon resonance, isothermal titration calorimetry and fluorescence-based thermal shift assays.

    Science.gov (United States)

    Rogez-Florent, Tiphaine; Duhamel, Laetitia; Goossens, Laurence; Six, Perrine; Drucbert, Anne-Sophie; Depreux, Patrick; Danzé, Pierre-Marie; Landy, David; Goossens, Jean-François; Foulon, Catherine

    2014-01-01

    This work describes the development of biophysical unbiased methods to study the interactions between new designed compounds and carbonic anhydrase II (CAII) enzyme. These methods have to permit both a screening of a series of sulfonamide derivatives and the identification of a lead compound after a thorough study of the most promising molecules. Interactions data were collected using surface plasmon resonance (SPR) and thermal shift assay (TSA). In the first step, experiments were performed with bovine CAII isoform and were extended to human CAII. Isothermal titration calorimetry (ITC) experiments were also conducted to obtain thermodynamics parameters necessary for the processing of the TSA data. Results obtained with this reference methodology demonstrate the effectiveness of SPR and TSA. KD values obtained from SPR data were in perfect accordance with ITC. For TSA, despite the fact that the absolute values of KD were quite different, the same affinity scale was obtained for all compounds. The binding affinities of the analytes studied vary by more than 50 orders of magnitude; for example, the KD value determined by SPR were 6 ± 4 and 299 ± 25 nM for compounds 1 and 3, respectively. This paper discusses some of the theoretical and experimental aspects of the affinity-based methods and evaluates the protein consumption to develop methods for the screening of further new compounds. The double interest of SPR, that is, for screening and for the quick thorough study of the interactions parameters (ka , kd , and KD ), leads us to choose this methodology for the study of new potential inhibitors. PMID:24375583

  18. INVESTIGATION ON THE CAUSES OF EUCALYPTUS KRAFT PULP BRIGHTNESS REVERSION

    OpenAIRE

    Kátia M. M. Eiras; Jorge Luiz Colodette; Ana Márcia M. L. Carvalho

    2005-01-01

    Some high brightness eucalyptus Kraft pulps have shown poor brightness stability. In most cases, the causes have notbeen identified and permanent solutions have not been found. This work focused on evaluating the brightness stability profile of pulpsbleached by in sequences such as O(DC)(PO)DD, O(DC)(PO)DP, OD(PO)DD, OD(PO)DP, ODHT(PO)DD, ODHT(PO)DP, OA/D(PO)DD, OA/D(PO)DP, OAD(PO)DD and O(Ze)D(PO). Brightness stability tests induced by according to Tappi UM200 procedureon samples bleached to...

  19. Study of Three-Dimensional Image Brightness Loss in Stereoscopy

    Directory of Open Access Journals (Sweden)

    Hsing-Cheng Yu

    2015-10-01

    Full Text Available When viewing three-dimensional (3D images, whether in cinemas or on stereoscopic televisions, viewers experience the same problem of image brightness loss. This study aims to investigate image brightness loss in 3D displays, with the primary aim being to quantify the image brightness degradation in the 3D mode. A further aim is to determine the image brightness relationship to the corresponding two-dimensional (2D images in order to adjust the 3D-image brightness values. In addition, the photographic principle is used in this study to measure metering values by capturing 2D and 3D images on television screens. By analyzing these images with statistical product and service solutions (SPSS software, the image brightness values can be estimated using the statistical regression model, which can also indicate the impact of various environmental factors or hardware on the image brightness. In analysis of the experimental results, comparison of the image brightness between 2D and 3D images indicates 60.8% degradation in the 3D image brightness amplitude. The experimental values, from 52.4% to 69.2%, are within the 95% confidence interval

  20. 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.

  1. 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

  2. Fluorescence of thermal control coatings on S0069 and A0114

    International Nuclear Information System (INIS)

    Many of the thermal control surfaces exposed to the space environment during the 5.8 year LDEF mission experienced changes in fluorescence. All of the thermal control coatings flown on LDEF experiments S0069 and A0114 were characterized for fluorescence under ambient conditions. Some of the black coatings, having protective overcoats, appear bright yellow under ultraviolet exposure. Urethane based coatings exhibited emission spectra shifts toward longer wavelengths in the visible range. Zinc oxide pigment based coatings experienced a quenching of fluorescence, while zinc orthotitanate pigment based and other ceramic type coatings had no measurable fluorescence

  3. The relation between isolated tree brightness temperature and grass background brightness temperature

    Science.gov (United States)

    Krusinger, A. E.

    1983-08-01

    This study involves thermal infrared measurement for the determination of the diurnal and seasonal aspects of the relations between isolated evergreen tress and a cut grass background and between a large truck brightness temperature and cut grass, uncut grass, and bare soil backgrounds. Seasonal changes in the tree brightness temperature-background brightness temperature contrast ranged from 4 to 5 C in February and March to 1 to 2 C in July. At night, the thermal contrast between trees and background was found to vary inversely with long wave incoming radiation, which is a measure of cloudiness. A study of the change in the thermal contrast during the night showed that, during clear weather, the contrast was at a peak a few hours after sundown and decreased the rest of the night. In overcast conditions, a reduced contrast peak occurred at sundown and very gradually diminished through the night. Isothermal conditions were found to occur in the early mornings, and the time of these occurrences changed seasonally, in a systematic manner.

  4. Larger Planet Radii Inferred from Stellar "Flicker" Brightness Variations of Bright Planet Host Stars

    CERN Document Server

    Bastien, Fabienne A; Pepper, Joshua

    2014-01-01

    Most extrasolar planets have been detected by their influence on their parent star, typically either gravitationally (the Doppler method) or by the small dip in brightness as the planet blocks a portion of the star (the transit method). Therefore, the accuracy with which we know the masses and radii of extrasolar planets depends directly on how well we know those of the stars, the latter usually determined from the measured stellar surface gravity, logg. Recent work has demonstrated that the short-timescale brightness variations ("flicker") of stars can be used to measure logg to a high accuracy of ~0.1-0.2 dex (Bastien et al. 2013). Here, we use flicker measurements of 289 bright (Kepmag<13) candidate planet-hosting stars with Teff=4500-6650 K to re-assess the stellar parameters and determine the resulting impact on derived planet properties. This re-assessment reveals that for the brightest planet-host stars, an astrophysical bias exists that contaminates the stellar sample with evolved stars: nearly 50%...

  5. High Brightness Neutron Source for Radiography

    Energy Technology Data Exchange (ETDEWEB)

    Cremer, J. T.; Piestrup, Melvin, A.; Gary, Charles, K.; Harris, Jack, L. Williams, David, J.; Jones, Glenn, E.; Vainionpaa, J. , H.; Fuller, Michael, J.; Rothbart, George, H.; Kwan, J., W.; Ludewigt, B., A.; Gough, R.., A..; Reijonen, Jani; Leung, Ka-Ngo

    2008-12-08

    This research and development program was designed to improve nondestructive evaluation of large mechanical objects by providing both fast and thermal neutron sources for radiography. Neutron radiography permits inspection inside objects that x-rays cannot penetrate and permits imaging of corrosion and cracks in low-density materials. Discovering of fatigue cracks and corrosion in piping without the necessity of insulation removal is possible. Neutron radiography sources can provide for the nondestructive testing interests of commercial and military aircraft, public utilities and petrochemical organizations. Three neutron prototype neutron generators were designed and fabricated based on original research done at the Lawrence Berkeley National Laboratory (LBNL). The research and development of these generators was successfully continued by LBNL and Adelphi Technology Inc. under this STTR. The original design goals of high neutron yield and generator robustness have been achieved, using new technology developed under this grant. In one prototype generator, the fast neutron yield and brightness was roughly 10 times larger than previously marketed neutron generators using the same deuterium-deuterium reaction. In another generator, we integrate a moderator with a fast neutron source, resulting in a high brightness thermal neutron generator. The moderator acts as both conventional moderator and mechanical and electrical support structure for the generator and effectively mimics a nuclear reactor. In addition to the new prototype generators, an entirely new plasma ion source for neutron production was developed. First developed by LBNL, this source uses a spiral antenna to more efficiently couple the RF radiation into the plasma, reducing the required gas pressure so that the generator head can be completely sealed, permitting the possible use of tritium gas. This also permits the generator to use the deuterium-tritium reaction to produce 14-MeV neutrons with increases

  6. Rainbow Vectors for Broad-Range Bacterial Fluorescence Labeling.

    Science.gov (United States)

    Barbier, Mariette; Damron, F Heath

    2016-01-01

    Since their discovery, fluorescent proteins have been widely used to study protein function, localization or interaction, promoter activity and regulation, drug discovery or for non-invasive imaging. They have been extensively modified to improve brightness, stability, and oligomerization state. However, only a few studies have focused on understanding the dynamics of fluorescent proteins expression in bacteria. In this work, we developed a set plasmids encoding 12 fluorescent proteins for bacterial labeling to facilitate the study of pathogen-host interactions. These broad-spectrum plasmids can be used with a wide variety of Gram-negative microorganisms including Escherichia coli, Pseudomonas aeruginosa, Burkholderia cepacia, Bordetella bronchiseptica, Shigella flexneri or Klebsiella pneumoniae. For comparison, fluorescent protein expression and physical characteristics in Escherichia coli were analyzed using fluorescence microscopy, flow cytometry and in vivo imaging. Fluorescent proteins derived from the Aequorea Victoria family showed high photobleaching, while proteins form the Discosoma sp. and the Fungia coccina family were more photostable for microscopy applications. Only E2-Crimson, mCherry and mKeima were successfully detected for in vivo applications. Overall, E2-Crimson was the fastest maturing protein tested in E. coli with the best overall performance in the study parameters. This study provides a unified comparison and comprehensive characterization of fluorescent protein photostability, maturation and toxicity, and offers general recommendations on the optimal fluorescent proteins for in vitro and in vivo applications. PMID:26937640

  7. Rainbow Vectors for Broad-Range Bacterial Fluorescence Labeling.

    Directory of Open Access Journals (Sweden)

    Mariette Barbier

    Full Text Available Since their discovery, fluorescent proteins have been widely used to study protein function, localization or interaction, promoter activity and regulation, drug discovery or for non-invasive imaging. They have been extensively modified to improve brightness, stability, and oligomerization state. However, only a few studies have focused on understanding the dynamics of fluorescent proteins expression in bacteria. In this work, we developed a set plasmids encoding 12 fluorescent proteins for bacterial labeling to facilitate the study of pathogen-host interactions. These broad-spectrum plasmids can be used with a wide variety of Gram-negative microorganisms including Escherichia coli, Pseudomonas aeruginosa, Burkholderia cepacia, Bordetella bronchiseptica, Shigella flexneri or Klebsiella pneumoniae. For comparison, fluorescent protein expression and physical characteristics in Escherichia coli were analyzed using fluorescence microscopy, flow cytometry and in vivo imaging. Fluorescent proteins derived from the Aequorea Victoria family showed high photobleaching, while proteins form the Discosoma sp. and the Fungia coccina family were more photostable for microscopy applications. Only E2-Crimson, mCherry and mKeima were successfully detected for in vivo applications. Overall, E2-Crimson was the fastest maturing protein tested in E. coli with the best overall performance in the study parameters. This study provides a unified comparison and comprehensive characterization of fluorescent protein photostability, maturation and toxicity, and offers general recommendations on the optimal fluorescent proteins for in vitro and in vivo applications.

  8. Ultra-bright alkylated graphene quantum dots

    Science.gov (United States)

    Feng, Lan; Tang, Xing-Yan; Zhong, Yun-Xin; Liu, Yue-Wen; Song, Xue-Huan; Deng, Shun-Liu; Xie, Su-Yuan; Yan, Jia-Wei; Zheng, Lan-Sun

    2014-10-01

    Highly efficient and stable photoluminescence (PL) are urgently desired for graphene quantum dots (GQDs) to facilitate their prospective applications as optical materials. Here, we report the facile and straightforward synthesis of alkylated graphene quantum dots (AGQDs) via the solvothermal reaction of propagatively alkylated graphene sheets (PAGenes). In contrast to most GQDs reported so far, the synthesized AGQDs process pH-independent and ultra-bright PL with a relative quantum yield of up to 65%. Structural and chemical composition characterization demonstrated that the synthesized AGQDs are nearly oxygen-defect-free with alkyl groups decorated on edges and basal plane, which may contribute to their greatly improved pH tolerance and high quantum efficiency. The photocatalytic performance of AGQDs-P25 nanocomposites was evaluated by the degradation of Rhodamine B under visible light. The photocatalytic rate is ca. 5.9 times higher than that of pure P25, indicating that AGQDs could harness the visible spectrum of sunlight for energy conversion or environmental therapy.Highly efficient and stable photoluminescence (PL) are urgently desired for graphene quantum dots (GQDs) to facilitate their prospective applications as optical materials. Here, we report the facile and straightforward synthesis of alkylated graphene quantum dots (AGQDs) via the solvothermal reaction of propagatively alkylated graphene sheets (PAGenes). In contrast to most GQDs reported so far, the synthesized AGQDs process pH-independent and ultra-bright PL with a relative quantum yield of up to 65%. Structural and chemical composition characterization demonstrated that the synthesized AGQDs are nearly oxygen-defect-free with alkyl groups decorated on edges and basal plane, which may contribute to their greatly improved pH tolerance and high quantum efficiency. The photocatalytic performance of AGQDs-P25 nanocomposites was evaluated by the degradation of Rhodamine B under visible light. The

  9. A Bright Future for Precision Medicine: Advances in Fluorescent Chemical Probe Design and Their Clinical Application.

    Science.gov (United States)

    Garland, Megan; Yim, Joshua J; Bogyo, Matthew

    2016-01-21

    The Precision Medicine Initiative aims to use advances in basic and clinical research to develop therapeutics that selectively target and kill cancer cells. Under the same doctrine of precision medicine, there is an equally important need to visualize these diseased cells to enable diagnosis, facilitate surgical resection, and monitor therapeutic response. Therefore, there is a great opportunity for chemists to develop chemically tractable probes that can image cancer in vivo. This review focuses on recent advances in the development of optical probes, as well as their current and future applications in the clinical management of cancer. The progress in probe development described here suggests that optical imaging is an important and rapidly developing field of study that encourages continued collaboration among chemists, biologists, and clinicians to further refine these tools for interventional surgical imaging, as well as for diagnostic and therapeutic applications. PMID:26933740

  10. Fast automated yeast cell counting algorithm using bright-field and fluorescence microscopic images

    OpenAIRE

    Hong, Dongpyo; Lee, Gwanghee; Jung, Neon Cheol; Jeon, Moongu

    2013-01-01

    Background The faithful determination of the concentration and viability of yeast cells is important for biological research as well as industry. To this end, it is important to develop an automated cell counting algorithm that can provide not only fast but also accurate and precise measurement of yeast cells. Results With the proposed method, we measured the precision of yeast cell measurements by using 0%, 25%, 50%, 75% and 100% viability samples. As a result, the actual viability measured ...

  11. Automated local bright feature image analysis of nuclear protein distribution identifies changes in tissue phenotype

    International Nuclear Information System (INIS)

    The organization of nuclear proteins is linked to cell and tissue phenotypes. When cells arrest proliferation, undergo apoptosis, or differentiate, the distribution of nuclear proteins changes. Conversely, forced alteration of the distribution of nuclear proteins modifies cell phenotype. Immunostaining and fluorescence microscopy have been critical for such findings. However, there is an increasing need for quantitative analysis of nuclear protein distribution to decipher epigenetic relationships between nuclear structure and cell phenotype, and to unravel the mechanisms linking nuclear structure and function. We have developed imaging methods to quantify the distribution of fluorescently-stained nuclear protein NuMA in different mammary phenotypes obtained using three-dimensional cell culture. Automated image segmentation of DAPI-stained nuclei was generated to isolate thousands of nuclei from three-dimensional confocal images. Prominent features of fluorescently-stained NuMA were detected using a novel local bright feature analysis technique, and their normalized spatial density calculated as a function of the distance from the nuclear perimeter to its center. The results revealed marked changes in the distribution of the density of NuMA bright features as non-neoplastic cells underwent phenotypically normal acinar morphogenesis. In contrast, we did not detect any reorganization of NuMA during the formation of tumor nodules by malignant cells. Importantly, the analysis also discriminated proliferating non-neoplastic cells from proliferating malignant cells, suggesting that these imaging methods are capable of identifying alterations linked not only to the proliferation status but also to the malignant character of cells. We believe that this quantitative analysis will have additional applications for classifying normal and pathological tissues

  12. Automated local bright feature image analysis of nuclear proteindistribution identifies changes in tissue phenotype

    Energy Technology Data Exchange (ETDEWEB)

    Knowles, David; Sudar, Damir; Bator, Carol; Bissell, Mina

    2006-02-01

    The organization of nuclear proteins is linked to cell and tissue phenotypes. When cells arrest proliferation, undergo apoptosis, or differentiate, the distribution of nuclear proteins changes. Conversely, forced alteration of the distribution of nuclear proteins modifies cell phenotype. Immunostaining and fluorescence microscopy have been critical for such findings. However, there is an increasing need for quantitative analysis of nuclear protein distribution to decipher epigenetic relationships between nuclear structure and cell phenotype, and to unravel the mechanisms linking nuclear structure and function. We have developed imaging methods to quantify the distribution of fluorescently-stained nuclear protein NuMA in different mammary phenotypes obtained using three-dimensional cell culture. Automated image segmentation of DAPI-stained nuclei was generated to isolate thousands of nuclei from three-dimensional confocal images. Prominent features of fluorescently-stained NuMA were detected using a novel local bright feature analysis technique, and their normalized spatial density calculated as a function of the distance from the nuclear perimeter to its center. The results revealed marked changes in the distribution of the density of NuMA bright features as non-neoplastic cells underwent phenotypically normal acinar morphogenesis. In contrast, we did not detect any reorganization of NuMA during the formation of tumor nodules by malignant cells. Importantly, the analysis also discriminated proliferating non-neoplastic cells from proliferating malignant cells, suggesting that these imaging methods are capable of identifying alterations linked not only to the proliferation status but also to the malignant character of cells. We believe that this quantitative analysis will have additional applications for classifying normal and pathological tissues.

  13. Fluorescent optical position sensor

    Science.gov (United States)

    Weiss, Jonathan D.

    2005-11-15

    A fluorescent optical position sensor and method of operation. A small excitation source side-pumps a localized region of fluorescence at an unknown position along a fluorescent waveguide. As the fluorescent light travels down the waveguide, the intensity of fluorescent light decreases due to absorption. By measuring with one (or two) photodetectors the attenuated intensity of fluorescent light emitted from one (or both) ends of the waveguide, the position of the excitation source relative to the waveguide can be determined by comparing the measured light intensity to a calibrated response curve or mathematical model. Alternatively, excitation light can be pumped into an end of the waveguide, which generates an exponentially-decaying continuous source of fluorescent light along the length of the waveguide. The position of a photodetector oriented to view the side of the waveguide can be uniquely determined by measuring the intensity of the fluorescent light emitted radially at that location.

  14. Fluorescence correlation spectroscopy

    NARCIS (Netherlands)

    M.A. Hink

    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

  15. Fluorenyl benzothiadiazole and benzoselenadiazole near-IR fluorescent probes for two-photon fluorescence imaging (Conference Presentation)

    Science.gov (United States)

    Belfield, Kevin D.; Yao, Sheng; Kim, Bosung; Yue, Xiling

    2016-03-01

    Imaging biological samples with two-photon fluorescence (2PF) microscopy has the unique advantage of resulting high contrast 3D resolution subcellular image that can reach up to several millimeters depth. 2PF probes that absorb and emit at near IR region need to be developed. Two-photon excitation (2PE) wavelengths are less concerned as 2PE uses wavelengths doubles the absorption wavelength of the probe, which means 2PE wavelengths for probes even with absorption at visible wavelength will fall into NIR region. Therefore, probes that fluoresce at near IR region with high quantum yields are needed. A series of dyes based on 5-thienyl-2, 1, 3-benzothiadiazole and 5-thienyl-2, 1, 3-benzoselenadiazole core were synthesized as near infrared two-photon fluorophores. Fluorescence maxima wavelengths as long as 714 nm and fluorescence quantum yields as high as 0.67 were achieved. The fluorescence quantum yields of the dyes were nearly constant, regardless of solvents polarity. These diazoles exhibited large Stokes shift (two-photon absorption cross sections (up to 2,800 GM), and high two-photon fluorescence figure of merit (FM , 1.04×10-2 GM). Cells incubated on a 3D scaffold with one of the new probes (encapsulated in Pluronic micelles) exhibited bright fluorescence, enabling 3D two-photon fluorescence imaging to a depth of 100 µm.

  16. Dark and bright vortex solitons in electromagnetically induced transparent media

    International Nuclear Information System (INIS)

    We show that dark and bright vortex solitons can exist in three-state electromagnetically induced transparent media under some appropriate conditions. We also analyse the stability of the dark and bright vortex solitons. This work may provide other research opportunities in nonlinear optical experiments and may result in a substantial impact on technology

  17. Analysis of Bright Harvest Remote Analysis for Residential Solar Installations

    Energy Technology Data Exchange (ETDEWEB)

    Nangle, John [National Renewable Energy Lab. (NREL), Golden, CO (United States); Simon, Joseph [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2015-06-17

    Bright Harvest provides remote shading analysis and design products for residential PV system installers. The National Renewable Energy Laboratory (NREL) through the NREL Commercialization Assistance Program, completed comparative assessments between on-site measurements and remotely calculated values to validate the accuracy of Bright Harvest’s remote shading and power generation.

  18. Modular Zero Energy. BrightBuilt Home

    Energy Technology Data Exchange (ETDEWEB)

    Aldrich, Robb [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States). Steven Winters Associates, Inc.; Butterfield, Karla [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States). Steven Winters Associates, Inc.

    2016-03-01

    Kaplan Thompson Architects (KTA) has specialized in sustainable, energy-efficient buildings, and they have designed several custom, zero-energy homes in New England. These zero-energy projects have generally been high-end, custom homes with budgets that could accommodate advanced energy systems. In an attempt to make zero energy homes more affordable and accessible to a larger demographic, KTA explored modular construction as way to provide high-quality homes at lower costs. In the mid-2013, KTA formalized this concept when they launched BrightBuilt Home (BBH). The BBH mission is to offer a line of architect-designed, high-performance homes that are priced to offer substantial savings off the lifetime cost of a typical home and can be delivered in less time. For the past two years, CARB has worked with BBH and Keiser Homes (the primary modular manufacturer for BBH) to discuss challenges related to wall systems, HVAC, and quality control. In Spring of 2014, CARB and BBH began looking in detail on a home to be built in Lincolnville, ME by Black Bros. Builders. This report details the solution package specified for this modular plan and the challenges that arose during the project.

  19. Intercomparisons of Nine Sky Brightness Detectors

    Directory of Open Access Journals (Sweden)

    Henk Spoelstra

    2011-10-01

    Full Text Available Nine Sky Quality Meters (SQMs have been intercompared during a night time measurement campaign held in the Netherlands in April 2011. Since then the nine SQMs have been distributed across the Netherlands and form the Dutch network for monitoring night sky brightness. The goal of the intercomparison was to infer mutual calibration factors and obtain insight into the variability of the SQMs under different meteorological situations. An ensemble average is built from the individual measurements and used as a reference to infer the mutual calibration factors. Data required additional synchronization prior to the calibration determination, because the effect of moving clouds combined with small misalignments emerges as time jitter in the measurements. Initial scatter of the individual instruments lies between ±14%. Individual night time sums range from −16% to +20%. Intercalibration reduces this to 0.5%, and −7% to +9%, respectively. During the campaign the smallest luminance measured was 0.657 ± 0.003 mcd/m2 on 12 April, and the largest value was 5.94 ± 0.03 mcd/m2 on 2 April. During both occurrences interfering circumstances like snow cover or moonlight were absent.

  20. Bright visible light emission from graphene

    Science.gov (United States)

    Kim, Young Duck; Kim, Hakseong; Cho, Yujin; Ryoo, Ji Hoon; Park, Cheol-Hwan; Kim, Pilkwang; Kim, Yong Seung; Lee, Sunwoo; Li, Yilei; Park, Seung-Nam; Shim Yoo, Yong; Yoon, Duhee; Dorgan, Vincent E.; Pop, Eric; Heinz, Tony F.; Hone, James; Chun, Seung-Hyun; Cheong, Hyeonsik; Lee, Sang Wook; Bae, Myung-Ho; Park, Yun Daniel

    2015-08-01

    Graphene and related two-dimensional materials are promising candidates for atomically thin, flexible and transparent optoelectronics. In particular, the strong light-matter interaction in graphene has allowed for the development of state-of-the-art photodetectors, optical modulators and plasmonic devices. In addition, electrically biased graphene on SiO2 substrates can be used as a low-efficiency emitter in the mid-infrared range. However, emission in the visible range has remained elusive. Here, we report the observation of bright visible light emission from electrically biased suspended graphene devices. In these devices, heat transport is greatly reduced. Hot electrons (˜2,800 K) therefore become spatially localized at the centre of the graphene layer, resulting in a 1,000-fold enhancement in thermal radiation efficiency. Moreover, strong optical interference between the suspended graphene and substrate can be used to tune the emission spectrum. We also demonstrate the scalability of this technique by realizing arrays of chemical-vapour-deposited graphene light emitters. These results pave the way towards the realization of commercially viable large-scale, atomically thin, flexible and transparent light emitters and displays with low operation voltage and graphene-based on-chip ultrafast optical communications.

  1. Antilensing: the bright side of voids.

    Science.gov (United States)

    Bolejko, Krzysztof; Clarkson, Chris; Maartens, Roy; Bacon, David; Meures, Nikolai; Beynon, Emma

    2013-01-11

    More than half of the volume of our Universe is occupied by cosmic voids. The lensing magnification effect from those underdense regions is generally thought to give a small dimming contribution: objects on the far side of a void are supposed to be observed as slightly smaller than if the void were not there, which together with conservation of surface brightness implies net reduction in photons received. This is predicted by the usual weak lensing integral of the density contrast along the line of sight. We show that this standard effect is swamped at low redshifts by a relativistic Doppler term that is typically neglected. Contrary to the usual expectation, objects on the far side of a void are brighter than they would be otherwise. Thus the local dynamics of matter in and near the void is crucial and is only captured by the full relativistic lensing convergence. There are also significant nonlinear corrections to the relativistic linear theory, which we show actually underpredicts the effect. We use exact solutions to estimate that these can be more than 20% for deep voids. This remains an important source of systematic errors for weak lensing density reconstruction in galaxy surveys and for supernovae observations, and may be the cause of the reported extra scatter of field supernovae located on the edge of voids compared to those in clusters. PMID:23383886

  2. Lyman Alpha Mapping Project (LAMP) Brightness Maps

    Science.gov (United States)

    Retherford, Kurt D.; Gladstone, G.; Stern, S.; Egan, A. F.; Miles, P. F.; Parker, J. W.; Greathouse, T. K.; Davis, M. W.; Slater, D. C.; Kaufmann, D. E.; Versteeg, M. H.; Feldman, P. D.; Hurley, D. M.; Pryor, W. R.; Hendrix, A. R.

    2010-10-01

    The Lyman Alpha Mapping Project (LAMP) is an ultraviolet (UV) spectrograph on the Lunar Reconnaissance Orbiter (LRO) that is designed to map the lunar albedo at far-UV wavelengths. LAMP primarily measures interplanetary Hydrogen Lyman-alpha sky-glow and far-UV starlight reflected from the night-side lunar surface, including permanently shadowed regions (PSRs) near the poles. Dayside observations are also obtained. Brightness maps sorted by wavelength (including the Lyman-alpha wavelength of 121.6 nm) are reported for the polar regions, with a few regions of interest reported in more detail. LAMP's spectral range of 58 nm to 196 nm includes a water ice spectral feature near 160 nm, which provides a diagnostic tool for detecting water on the lunar surface that is complementary to recent discoveries using infrared and radio frequency techniques. Progress towards producing far-UV albedo maps and searching for water ice signatures will be reported. We'll discuss how LAMP data may address questions regarding how water is formed on the moon, transported through the lunar atmosphere, and deposited in the PSRs.

  3. Chromatic variations suppress suprathreshold brightness variations.

    Science.gov (United States)

    Kingdom, Frederick A A; Bell, Jason; Gheorghiu, Elena; Malkoc, Gokhan

    2010-01-01

    Most objects in natural scenes are suprathreshold in both color (chromatic) and luminance contrast. How salient is each dimension? We have developed a novel method employing a stimulus similar to that used by B. C. Regan and J. D. Mollon (1997) who studied the relative saliencies of the two chromatic cardinal directions. Our stimuli consist of left- and right-oblique modulations of color and/or luminance defined within a lattice of circles. In the "separated" condition, the two modulations were presented separately as forced-choice pairs, and the task was to indicate which was more salient. In the "combined" condition, the two orthogonal-in-orientation modulations were added, and the task was to indicate the more salient orientation. The ratio of color to luminance contrast at the PSE was calculated for both conditions. Across color directions, 48% more luminance contrast relative to color contrast was required to achieve a PSE in the "combined" compared to the "separated" condition. A second experiment showed that the PSE difference was due to the luminance being masked by the color, rather than due to superior color grouping. We conclude that suprathreshold brightness variations are masked by suprathreshold color variations. PMID:20884478

  4. Energy balance in a bright active prominence

    International Nuclear Information System (INIS)

    The transitions between ten levels and hydrogen atom continuum and 4S, 3D, 4P, Ca+ terms in a bright active prominence are considered. The role of electron impacts and solar radiation scattering taking account of optical thicknesses in all frequencies is considered. It has been found that hydrogen atoms and calcium ions radiate approximately equal amount of energy: 2.4x107 and 1.3x107 erg/cm2xs., respectively. The hydrogen atom radiation is by 2/3 due to solar radiation scattering, the contribution of the scattered radiation for various series and separate lines being unequal. The radiation in the n, k lines and in Ca+ infrared lines is almost completely ensured by electron impacts. Only the tenth part of the necessary energy is added on account of the solar radiation absorption. The total prominence radiation is half ensured due to solar radiation scattering. Approximately the same amount of energ is taken from the electron gas. The higher is q, the more significant becomes the role of electron impacts in hydrogen atom excitation and ionization. The q prominence duty factor value is near to unity

  5. Dark Skies, Bright Kids Year 6

    Science.gov (United States)

    Liss, Sandra; Troup, Nicholas William; Johnson, Kelsey E.; Barcos-Munoz, Loreto D.; Beaton, Rachael; Bittle, Lauren; Borish, Henry J.; Burkhardt, Andrew; Corby, Joanna; Dean, Janice; Hancock, Danielle; King, Jennie; Prager, Brian; Romero, Charles; Sokal, Kimberly R.; Stierwalt, Sabrina; Wenger, Trey; Zucker, Catherine

    2015-01-01

    Now entering our sixth year of operation, Dark Skies, Bright Kids (DSBK) is an entirely volunteer-run outreach organization based out of the Department of Astronomy at the University of Virginia. Our core mission is to enhance elementary science education and literacy in central Virginia through fun, hands-on activities that introduce basic Astronomy concepts beyond Virginia's Standards of Learning. Our primary focus is hosting an 8-10 week after-school astronomy club at underserved elementary and middle schools. Each week, DSBK volunteers take the role of coaches to introduce astronomy-related concepts ranging from the Solar System to galaxies to astrobiology, and to lead students in interactive learning activities. Another hallmark of DSBK is hosting our Annual Central Virginia Star Party, a free event open to the community featuring star-gazing and planetarium shows.DSBK has amassed over 15,000 contact hours since 2009 and we continue to broaden our impact. One important step we have taken in the past year is to establish a graduate student led assessment program to identify and implement directed learning goals for DSBK outreach. The collection of student workbooks, observations, and volunteer surveys indicates broad scale success for the program both in terms of student learning and their perception of science. The data also reveal opportunities to improve our organizational and educational practices to maximize student achievement and overall volunteer satisfaction for DSBK's future clubs and outreach endeavors.

  6. Magnetic flux supplement to coronal bright points

    CERN Document Server

    Mou, Chaozhou; Xia, Lidong; Madjarska, Maria S; Li, Bo; Fu, Hui; Jiao, Fangran; Hou, Zhenyong

    2015-01-01

    Coronal bright points (BPs) are associated with magnetic bipolar features (MBFs) and magnetic cancellation. Here, we investigate how BP-associated MBFs form and how the consequent magnetic cancellation occurs. We analyse longitudinal magnetograms from the Helioseismic and Magnetic Imager to investigate the photospheric magnetic flux evolution of 70 BPs. From images taken in the 193 A passband of the Atmospheric Imaging Assembly (AIA) we dermine that the BPs' lifetimes vary from 2.7 to 58.8 hours. The formation of the BP MBFs is found to involve three processes, namely emergence, convergence and local coalescence of the magnetic fluxes. The formation of a MBF can involve more than one of these processes. Out of the 70 cases, flux emergence is the main process of a MBF buildup of 52 BPs, mainly convergence is seen in 28, and 14 cases are associated with local coalescence. For MBFs formed by bipolar emergence, the time difference between the flux emergence and the BP appearance in the AIA 193 \\AA\\ passband varie...

  7. Intrinsic brightness temperatures of blazar jets at 15 GHz

    Directory of Open Access Journals (Sweden)

    Hovatta Talvikki

    2013-12-01

    Full Text Available We have developed a new Bayesian Markov Chain Monte Carlo method to deconvolve light curves of blazars into individual flares, including proper estimation of the fit errors. We use the method to fit 15GHzlight curves obtained within the OVRO 40-m blazar monitoring program where a large number of AGN have been monitored since 2008 in support of the Fermi Gamma-Ray Space Telescope mission. The time scales obtained from the fitted models are used to calculate the variability brightness temperature of the sources. Additionally, we have calculated brightness temperatures of a sample of these objects using Very Long Baseline Array data from the MOJAVE survey. Combining these two data sets enables us to study the intrinsic brightness temperature distribution in these blazars at 15 GHz. Our preliminary results indicate that the mean intrinsic brightness temperature in a sample of 14 sources is near the equipartition brightness temperature of ~ 1011K.

  8. Determination of trace amounts of hexavalent chromium in drinking waters by dispersive microsolid-phase extraction using modified multiwalled carbon nanotubes combined with total reflection X-ray fluorescence spectrometry

    International Nuclear Information System (INIS)

    A methodology based on the combination of dispersive microsolid-phase extraction (DMSPE) with total reflection X-ray fluorescence (TXRF) spectrometry is proposed for the determination of hexavalent chromium in drinking waters. Multiwalled carbon nanotubes (MWCNTs) modified with the anionic exchanger tricaprylmethylammonium chloride (Aliquat 336) were used as solid sorbents. After the sorption process of Cr(VI) on the modified MWCNTs, the aqueous sample was separated by centrifugation and the loaded MWCNTs were suspended using a small volume of an internal standard solution and analyzed directly by a benchtop TXRF spectrometer, without any elution step. Parameters affecting the extraction process (pH and volume of the aqueous sample, amount of MWCNTs, extraction time) and TXRF analysis (volume of internal standard, volume of deposited suspension on the reflector, drying mode, and instrumental parameters) have been carefully evaluated to test the real capability of the developed methodology for the determination of Cr(VI) at trace levels. Using the best analytical conditions, it was found that the minimum Cr(VI) content that can be detected in an aqueous solution was 3 μg L−1. This value is almost 20 times lower than the maximum hexavalent chromium content permissible in drinking waters, according to the World Health Organization (WHO). Recoveries for spiked tap and mineral water samples were, in most cases, in the range of 101–108% which demonstrates the suitability of the TXRF methodology for monitoring Cr(VI) at trace levels in drinking water samples. - Highlights: • A method using DMSPE and TXRF is proposed for Cr(VI) determination in water. • CNTs modified with a commercial anionic exchanger are used for the DMSPE. • The detection limit for hexavalent chromium is 3 μg L−1. • Accuracy and precision are suitable for the analysis of tap and mineral waters

  9. Determination of trace amounts of hexavalent chromium in drinking waters by dispersive microsolid-phase extraction using modified multiwalled carbon nanotubes combined with total reflection X-ray fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Bahadir, Z. [Department of Chemistry, Giresun University, Giresun (Turkey); Bulut, V.N. [Macka Vocational School, Karadeniz Technical University, Macka, Trabzon (Turkey); Hidalgo, M. [Department of Chemistry, Faculty of Sciences, University of Girona, Girona (Spain); Soylak, M. [Department of Chemistry, Faculty of Sciences, Erciyes University, Kayseri (Turkey); Marguí, E., E-mail: eva.margui@udg.edu [Department of Chemistry, Faculty of Sciences, University of Girona, Girona (Spain)

    2015-05-01

    A methodology based on the combination of dispersive microsolid-phase extraction (DMSPE) with total reflection X-ray fluorescence (TXRF) spectrometry is proposed for the determination of hexavalent chromium in drinking waters. Multiwalled carbon nanotubes (MWCNTs) modified with the anionic exchanger tricaprylmethylammonium chloride (Aliquat 336) were used as solid sorbents. After the sorption process of Cr(VI) on the modified MWCNTs, the aqueous sample was separated by centrifugation and the loaded MWCNTs were suspended using a small volume of an internal standard solution and analyzed directly by a benchtop TXRF spectrometer, without any elution step. Parameters affecting the extraction process (pH and volume of the aqueous sample, amount of MWCNTs, extraction time) and TXRF analysis (volume of internal standard, volume of deposited suspension on the reflector, drying mode, and instrumental parameters) have been carefully evaluated to test the real capability of the developed methodology for the determination of Cr(VI) at trace levels. Using the best analytical conditions, it was found that the minimum Cr(VI) content that can be detected in an aqueous solution was 3 μg L{sup −1}. This value is almost 20 times lower than the maximum hexavalent chromium content permissible in drinking waters, according to the World Health Organization (WHO). Recoveries for spiked tap and mineral water samples were, in most cases, in the range of 101–108% which demonstrates the suitability of the TXRF methodology for monitoring Cr(VI) at trace levels in drinking water samples. - Highlights: • A method using DMSPE and TXRF is proposed for Cr(VI) determination in water. • CNTs modified with a commercial anionic exchanger are used for the DMSPE. • The detection limit for hexavalent chromium is 3 μg L{sup −1}. • Accuracy and precision are suitable for the analysis of tap and mineral waters.

  10. Nanoluciferase signal brightness using furimazine substrates opens bioluminescence resonance energy transfer to widefield microscopy.

    Science.gov (United States)

    Kim, Jiho; Grailhe, Regis

    2016-08-01

    Fluorescence and bioluminescence resonance energy transfer (FRET, BRET) techniques are powerful tools for studying protein-protein interactions in cellular assays. In contrast to fluorescent proteins, chemiluminescent proteins do not require excitation light, known to trigger autofluorescence, phototoxicity, and photobleaching. Regrettably, low signal intensity of luciferase systems restricts their usage as they require specialized microscopes equipped with ultra low-light imaging cameras. In this study, we report that bioluminescence quantification in living cells using a standard widefield automated microscope dedicated to screening and high content analysis is possible with the newer luciferase systems, Nanoluciferase (Nluc). With such equipment, we showed that robust intramolecular BRET can be measured using a combination of Nluc and yellow fluorescent protein (YFP). Using the human Superoxide Dismutase 1 (SOD1) dimer model, we next validated that intermolecular BRET could be quantified at a single cell level. The enhanced signal brightness of Nluc enabling BRET imaging to widefield microscopy shows strong potential to open up single cell protein-protein interactions studies to a wider audience. © 2016 International Society for Advancement of Cytometry. PMID:27144967

  11. Electron emission from nano-structured carbon composite materials and fabrication of high-quality electron emitters by using plasma technology

    International Nuclear Information System (INIS)

    Many trials have been done to fabricate high-quality electron-emitters from nano-composite carbon materials (such as nano-diamond, carbon nano tubes and others) by means of a variety of plasma chemical-vapor-deposition (CVD) techniques. Based upon the mechanism of electron emission, we have proposed several strategic guide lines for the fabrication of good emitters. Then, following these lines, several types of emitters were tried. One of the emitters has shown a worldclass, top ranking for fabricating very bright lamps: namely, a low turn-on voltage (0.5 ∼ 1 V/μm to induce 10 μA/cm2 emission current) to emit a 1 mA/cm2 current at 3 V/μm and 100 mA/cm2 current at a slightly higher applied voltage. The bright lamps are Mercury-free fluorescence lamps to exhibit brightness of ∼105 cd/m2 with high efficiency of ∼100 lm/w.

  12. Dark Skies, Bright Kids: Year 2

    Science.gov (United States)

    Carlberg, Joleen K.; Johnson, K.; Lynch, R.; Walker, L.; Beaton, R.; Corby, J.; de Messieres, G.; Drosback, M.; Gugliucci, N.; Jackson, L.; Kingery, A.; Layman, S.; Murphy, E.; Richardson, W.; Ries, P.; Romero, C.; Sivakoff, G.; Sokal, K.; Trammell, G.; Whelan, D.; Yang, A.; Zasowski, G.

    2011-01-01

    The Dark Skies, Bright Kids (DSBK) outreach program brings astronomy education into local elementary schools in central Virginia's Southern Albemarle County through an after-school club. Taking advantage of the unusually dark night skies in the rural countryside, DSBK targets economically disadvantaged schools that tend to be underserved due to their rural locale. The goals of DSBK are to foster children's natural curiosity, demonstrate that science is a fun and creative process, challenge students' conceptions of what a scientist is and does, and teach some basic astronomy. Furthermore, DSBK works to assimilate families into students' education by holding family observing nights at the school. Now in its third semester, DSBK has successfully run programs at two schools with very diverse student populations. Working with these students has helped us to revise our activities and to create new ones. A by-product of our work has been the development of lesson plans, complete with learning goals and detailed instructions, that we make publically available on our website. This year we are expanding our repertoire with our new planetarium, which allows us to visualize topics in novel ways and supplements family observing on cloudy nights. The DSBK volunteers have also created a bilingual astronomy artbook --- designed, written, and illustrated by UVa students --- that we will publish and distribute to elementary schools in Virginia. Our book debuted at the last AAS winter meeting, and since then it has been extensively revised and updated with input from many individuals, including parents, professional educators, and a children's book author. Because the club is currently limited to serving a few elementary schools, this book will be part of our efforts to broaden our impact by bringing astronomy to schools we cannot go to ourselves and reaching out to Spanish-speaking communities at the same time.

  13. Dark Skies, Bright Kids! Year 3

    Science.gov (United States)

    Whelan, David G.; Johnson, K. E.; Barcos-Munoz, L. D.; Beaton, R. L.; Borish, J.; Corby, J. F.; Dorsey, G.; Gugliucci, N. E.; Prager, B. J.; Ries, P. A.; Romero, C. E.; Sokal, K. R.; Tang, X.; Walker, L. M.; Yang, A. J.; Zasowski, G.

    2012-01-01

    Dark Skies, Bright Kids! (DSBK) is a program that brings astronomy education to elementary schools throughout central Virginia. In a relaxed, out-of-classroom atmosphere, we are able to foster the innate curiosity that young students have about science and the world around them. We target schools that are under-served due to their rural locale or special needs students, demonstrating that science is a fun and creative process to a segment of the population that might not otherwise be exposed to astronomy. Families are included in the learning experience during semi-annual `star parties'. Since last January, we have expanded the breadth and depth of our educational capabilities. We have developed new programs for use in our digital planetarium. We held the first Central Virginia Star Party, providing an atmosphere where local children from multiple schools were able to share their love for astronomy. Local government and University officials were also invited so that they could experience our focused science outreach. Most recently, we have become part of Ivy Creek School's Club Day activities, bringing our program to a new segment of the elementary school system in Albemarle County: those that have `low-incidence' disabilities, requiring special attention. We continue to develop a curriculum for after-school programs that functions as either a series of one-time activities or several months of focused outreach at one school. Many of these activities are provided on our website, http://www.astro.virginia.edu/dsbk/, for the wider astronomical community, including the new planetarium work. We have extended our book project to include two bilingual astronomy books called `Snapshots of the Universe,' one in Spanish and English, the other in French and English. These books introduce young people to some of the many wonders of the Universe through art and captions developed by DSBK volunteers.

  14. Dark Skies, Bright Kids! Year 5

    Science.gov (United States)

    Prager, Brian; Johnson, K. E.; Barcos-Munoz, L. D.; Beaton, R.; Bittle, L.; Borish, H.; Burkhardt, A.; Corby, J.; Damke, G.; Dean, J.; Dorsey, G.; Graninger, D.; Lauck, T.; Liss, S.; Oza, A.; Peacock, S.; Romero, C.; Sokal, K. R.; Stierwalt, S.; Walker, L.; Wenger, T.; Zucker, C.

    2014-01-01

    Our public outreach group Dark Skies, Bright Kids! (DSBK) fosters science literacy in Virginia by bringing a hands-on approach to astronomy that engages children's natural excitement and curiosity. We are an entirely volunteer-run group based out of the Department of Astronomy at the University of Virginia and we enthusiastically utilize astronomy as a 'gateway science.' We create long-term relationships with students during an 8 to 10 week long, after-school astronomy club at under served elementary schools in neighboring counties, and we visited 3 different schools in 2013. Additionally, we organize and participate in science events throughout the community. The fifth year of DSBK was marked by surpassing 10,000 contact hours in Spring 2013 Semester and by ringing in the fall semester with our biggest, most successful star party to date. We hosted the Third Annual Central Virginia Star Party, free and open to the community to encourage families to enjoy astronomy together. Nearly four hundred people of all ages attended, double the number from previous years. Joining with local astronomical societies, we offered an enlightening and exciting night with resources rarely accessible to the public, such as an IR camera and a portable planetarium. With numerous telescopes pointed at the sky, and a beautifully clear night with views of the Milky Way, the International Space Station, and numerous meteors, the star party was a fantastic opportunity to introduce many of our guests to the natural wonders of our night sky and enjoy some of the darkest skies on the eastern seaboard.

  15. Dark Skies, Bright Kids! Year 4

    Science.gov (United States)

    Sokal, Kimberly R.; Johnson, K. E.; Barcos-Munoz, L. D.; Beaton, R.; Borish, J.; Crawford, S. B.; Corby, J.; Damke, G.; Dean, J.; Dorsey, G.; Jackson, L.; Liss, S.; Oza, A.; Peacock, S.; Prager, B.; Romero, C.; Sivakoff, G. R.; Walker, L.; Whelan, D. G.; Zucker, C.

    2013-01-01

    Aiming to engage young children's natural excitement and curiosity, the outreach group Dark Skies, Bright Kids (DSBK) brings a hands-on approach to astronomy to elementary schools in Virginia. We hope to enhance children's view and understanding of science while exploring the Universe using fun activities. DSBK focuses on rural and underserved schools in Albemarle County and offers a semester-long astronomy club for third through fifth grade students. We believe regular interactions foster personal relationships between students and volunteers that encourage a life-long interest in science. In our fourth year of hosting clubs, we returned to Ivy Creek Elementary School, where we saw wonderful responses from a special group of students with `low-incidence' disabilities. DSBK has grown to realize a broader reach beyond local astronomy clubs; we hope to ignite a spark of interest in astronomy and science more widely- in more children, their families, and their teachers. We also hosted the Second Annual Central Virginia Star Party with an open invitation to the community to encourage families to enjoy astronomy together. Throughout the year, DSBK now holds 'one-off' programs (akin to astronomy field days) for elementary schools and children's groups throughout Virginia. Furthermore, we are in the final stages of a project to create two bilingual astronomy books called "Snapshots of the Universe", in Spanish and French with English translations. This art book will be made available online and we are working to get a copy in every elementary school in the state. DSBK has begun to reach out to elementary school teachers in order to provide them with useful and engaging classroom material. We have adapted our volunteer-created activities into useful and ready-to-use lessons, available online. After improvements based on research through interactions and feedback from teachers, we have explicitly identified the learning goals in terms of Virginia's Standards of Learning

  16. The use of fluorescence enhancement to improve the microscopic diagnosis of falciparum malaria

    OpenAIRE

    Liu Paul; Guy Rebecca; Pennefather Peter; Crandall Ian

    2007-01-01

    Abstract Background Giemsa staining of thick blood smears remains the "gold standard" for detecting malaria. However, this method is not very good for diagnosing low-level infections. A method for the simultaneous staining of Plasmodium-parasitized culture and blood smears for both bright field and fluorescence was developed and its ability to improve detection efficiency tested. Methods A total of 22 nucleic acid-specific fluorescent dyes were tested for their ability to provide easily obser...

  17. Hubble Space Telescope Near-Ultraviolet Spectroscopy of Bright CEMP-s Stars

    OpenAIRE

    Placco, Vinicius M.; Beers, Timothy C.; Ivans, Inese I.; Filler, Dan; Imig, Julie A.; Roederer, Ian U.; Abate, Carlo; Hansen, Terese; Cowan, John J.; Frebel, Anna; Lawler, James E.; Schatz, Hendrik; Sneden, Christopher; Sobeck, Jennifer S.; Aoki, Wako

    2015-01-01

    We present an elemental-abundance analysis, in the near-ultraviolet (NUV) spectral range, for the bright carbon-enhanced metal-poor (CEMP) stars HD196944 (V = 8.40, [Fe/H] = -2.41) and HD201626 (V = 8.16, [Fe/H] = -1.51), based on data acquired with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope. Both of these stars belong to the sub-class CEMP-s, and exhibit clear over-abundances of heavy elements associated with production by the slow neutron-capture process. ...

  18. The lowest spatial frequency channel determines brightness perception.

    Science.gov (United States)

    Perna, A; Morrone, M C

    2007-05-01

    This study investigates the role played by individual spatial scales in determining the apparent brightness of greyscale patterns. We measured the perceived difference in brightness across an edge in the presence of notch filtering and high-pass filtering for two stimulus configurations, one that elicits the perception of transparency and one that appears opaque. For both stimulus configurations, the apparent brightness of the surfaces delimited by the border decreased monotonically with progressive (ideal) high-pass filtering, with a critical cut-off at 1 c/deg. Using two octave ideal notch filtering, the maximum detrimental effect on apparent brightness was observed at about 1c/deg. Critical frequencies for apparent brightness did not vary with contrast, viewing distance, or surface size, suggesting that apparent brightness is determined by the channel tuned at 1 c/deg. Modelling the data with the local energy model [Morrone, M. C., & Burr, D. C. (1988). Feature detection in human vision: a phase dependent energy model. Proceedings of the Royal Society (London), B235, 221-245] at 1c/deg confirmed the suggestion that this channel mediates apparent brightness for both opaque and transparent borders, with no need for pooling or integration across spatial channels. PMID:17395237

  19. Brightness of synchrotron radiation from undulators and bending magnets

    International Nuclear Information System (INIS)

    We consider the maximum of the Wigner distribution (WD) of synchrotron radiation (SR) fields as a possible definition of SR source brightness. Such figure of merit was originally introduced in the SR community by Kim. The brightness defined in this way is always positive and, in the geometrical optics limit, can be interpreted as maximum density of photon flux in phase space. For undulator and bending magnet radiation from a single electron, the WD function can be explicitly calculated. In the case of an electron beam with a finite emittance the brightness is given by the maximum of the convolution of a single electron WD function and the probability distribution of the electrons in phase space. In the particular case when both electron beam size and electron beam divergence dominate over the diffraction size and the diffraction angle, one can use a geometrical optics approach. However, there are intermediate regimes when only the electron beam size or the electron beam divergence dominate. In this asymptotic cases the geometrical optics approach is still applicable, and the brightness definition used here yields back once more the maximum photon flux density in phase space. In these intermediate regimes we find a significant numerical disagreement between exact calculations and the approximation for undulator brightness currently used in literature. We extend the WD formalism to a satisfactory theory for the brightness of a bending magnet. We find that in the intermediate regimes the usually accepted approximation for bending magnet brightness turns out to be inconsistent even parametrically.

  20. Near infrared fluorescent biliproteins generated from bacteriophytochrome AphB of Nostoc sp. PCC 7120.

    Science.gov (United States)

    Yuan, Che; Li, Hui-Zhen; Tang, Kun; Gärtner, Wolfgang; Scheer, Hugo; Zhou, Ming; Zhao, Kai-Hong

    2016-04-13

    The genome of the cyanobacterium Nostoc sp. PCC 7120 encodes a large number of putative bacteriophytochrome and cyanobacteriochrome photoreceptors that, due to their long-wavelength absorption and fluorescence emission, might serve as fluorescent tags in intracellular investigations. We show that the PAS-GAF domain of the bacteriophytochrome, AphB, binds biliverdin covalently and exhibits, besides its reversible photochemistry, a moderate fluorescence in the near infrared (NIR) spectral region. It was selected for further increasing the brightness while retaining the NIR fluorescence. In the first step, amino acids assumed to improve fluorescence were selectively mutated. The resulting variants were then subjected to several rounds of random mutagenesis and screened for enhanced fluorescence in the NIR. The brightness of optimized PAS-GAF variants increased more than threefold compared to that of wt AphB(1-321), with only insignificant spectral shifts (Amax around 695 nm, and Fmax around 720 nm). In general, the brightness increases with decreasing wavelengths, which allows for a selection of the fluorophore depending on the optical properties of the tissue. A spectral heterogeneity was observed when residue His260, located in close proximity to the chromophore, was mutated to Tyr, emphasizing the strong effects of the environment on the electronic properties of the bound biliverdin chromophore. PMID:27004456

  1. Common fluorescent proteins for single-molecule localization microscopy

    Science.gov (United States)

    Klementieva, Natalia V.; Bozhanova, Nina G.; Mishina, Natalie M.; Zagaynova, Elena V.; Lukyanov, Konstantin A.; Mishin, Alexander S.

    2015-07-01

    Super-resolution techniques for breaking the diffraction barrier are spread out over multiple studies nowadays. Single-molecule localization microscopy such as PALM, STORM, GSDIM, etc allow to get super-resolved images of cell ultrastructure by precise localization of individual fluorescent molecules via their temporal isolation. However, these methods are supposed the use of fluorescent dyes and proteins with special characteristics (photoactivation/photoconversion). At the same time, there is a need for retaining high photostability of fluorophores during long-term acquisition. Here, we first showed the potential of common red fluorescent protein for single-molecule localization microscopy based on spontaneous intrinsic blinking. Also, we assessed the effect of different imaging media on photobleaching of these fluorescent proteins. Monomeric orange and red fluorescent proteins were examined for stochastic switching from a dark state to a bright fluorescent state. We studied fusions with cytoskeletal proteins in NIH/3T3 and HeLa cells. Imaging was performed on the Nikon N-STORM system equipped with EMCCD camera. To define the optimal imaging conditions we tested several types of cell culture media and buffers. As a result, high-resolution images of cytoskeleton structure were obtained. Essentially, low-intensity light was sufficient to initiate the switching of tested red fluorescent protein reducing phototoxicity and provide long-term live-cell imaging.

  2. Lamp spectrum and spatial brightness at photopic levels

    DEFF Research Database (Denmark)

    Fotios, Steve; Atli, Deniz; Cheal, Chris; Houser, Kevin; Logadóttir, Ásta

    2015-01-01

    lower illuminance with potential reductions in energy consumption. Consideration of experimental design was used to review 70 studies of spatial brightness. Of these, the 19 studies considered to provide credible evidence of SPD effects were used to explore metrics for predicting the effect of SPD but......Light sources are available in a variety of spectral power distributions (SPDs) and this affects spatial brightness in a manner not predicted by quantities such as illuminance. Tuning light source SPD to better match the sensitivity of visual perception may allow the same spatial brightness but at...

  3. First magnitude a book of the bright sky

    CERN Document Server

    Kaler, James B

    2012-01-01

    "First Magnitude" is an entry-level book for readers with brightly lit skies. Its purpose is to show them that all is not lost, that they can still enjoy personal astronomy and have an appreciation of the heavens no matter where they live. It concentrates on the Sun, Moon, the five bright planets, and on the 23 brightest stars, which are visible from just about anywhere. The book concludes with bright ephemeral phenomena: meteors, comets, and exploding stars. The concept is a platform for introducing the reader to the wonders of the nighttime and daytime skies and serves as an introduction to

  4. Robust, directed assembly of fluorescent nanodiamonds

    CERN Document Server

    Kianinia, Mehran; Shimoni, Olga; Randolph, Steven J; Toth, Milos; Aharonovich, Igor; Lobo, Charlene J

    2016-01-01

    Arrays of fluorescent nanoparticles are highly sought after for applications in sensing and nanophotonics. Here we present a simple and robust method of assembling fluorescent nanodiamonds into macroscopic arrays. Remarkably, the yield of this directed assembly process is greater than 90% and the assembled patterns withstand ultra-sonication for more than three hours. The assembly process is based on covalent bonding of carboxyl to amine functional carbon seeds and is applicable to any material, and to non-planar surfaces. Our results pave the way to directed assembly of sensing and nanophotonics devices.

  5. Fluorescent fiber diagnostics

    Science.gov (United States)

    Toeppen, John S.

    1994-01-01

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

  6. Lyα EMISSION FROM COSMIC STRUCTURE. I. FLUORESCENCE

    International Nuclear Information System (INIS)

    We present predictions for the fluorescent Lyα emission signature arising from photoionized, optically thick structures in smoothed particle hydrodynamic cosmological simulations of a ΛCDM universe using a Monte Carlo Lyα radiative transfer code. We calculate the expected Lyα image and two-dimensional spectra for gas exposed to a uniform ultraviolet ionizing background as well as gas exposed additionally to the photoionizing radiation from a local quasar, after correcting for the self-shielding of hydrogen. As a test of our numerical methods and for application to current observations, we examine simplified analytic structures that are uniformly or anisotropically illuminated. We compare these results with recent observations. We discuss future observing campaigns on large telescopes and realistic strategies for detecting fluorescence owing to the ambient metagalactic ionization and in regions close to bright quasars. While it will take hundreds of hours on the current generation of telescopes to detect fluorescence caused by the ultraviolet background alone, our calculations suggest that on the order of 10 sources of quasar-induced fluorescent Lyα emission should be detectable after a 10 hr exposure in a 10 arcmin2 field around a bright quasar. These observations will help probe the physical conditions in the densest regions of the intergalactic medium as well as the temporal light curves and isotropy of quasar radiation.

  7. Hubble ultra deep field object surface brightness variation

    International Nuclear Information System (INIS)

    The technique of adjacent pixel brightness variation in log scale was applied to ultra deep field objects captured by the Hubble telescope. The local surface brightness fluctuation has a Gaussian-like distribution implying a random accretion of material, with collisions, as a random-walk motion. The larger fluctuation of log brightness in the mid to outer regions of some galaxies is consistent with the presence of dark matter. The absence of such fluctuation enhancement in two i-drop candidates at z ∼ 3 may mean that some dark matter is the result of nucleosynthesis in the evolution process. Large fluctuation in the B+V bands in contrast to the i+z band near the center in an i-drop candidate at z ∼ 3 was interpreted to be an AGN center. The distribution average shifts towards zero for more spiral galaxies, signifying the use of local surface brightness fluctuation distribution as a morphology parameter

  8. Operational Bright-Band Snow Level Detection Using Doppler Radar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A method to detect the bright-band snow level from radar reflectivity and Doppler vertical velocity data collection with an atmospheric profiling Doppler radar. The...

  9. SMEX03 SSM/I Brightness Temperature Data, Georgia

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides brightness temperature data acquired during the Soil Moisture Experiment 2003 (SMEX03) by the Special Sensor Microwave/Imager (SSM/I). The...

  10. SMEX03 SSM/I Brightness Temperature Data, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides brightness temperature data acquired during the Soil Moisture Experiment 2003 (SMEX03) by the Special Sensor Microwave/Imager (SSM/I). The...

  11. An observational correlation between stellar brightness variations and surface gravity

    CERN Document Server

    Bastien, Fabienne A; Basri, Gibor; Pepper, Joshua

    2013-01-01

    Surface gravity is one of a star's basic properties, but it is difficult to measure accurately, with typical uncertainties of 25-50 per cent if measured spectroscopically and 90-150 per cent photometrically. Asteroseismology measures gravity with an uncertainty of about two per cent but is restricted to relatively small samples of bright stars, most of which are giants. The availability of high-precision measurements of brightness variations for >150,000 stars provides an opportunity to investigate whether the variations can be used to determine surface gravities. The Fourier power of granulation on a star's surface correlates physically with surface gravity; if brightness variations on timescales of hours arise from granulation, then such variations should correlate with surface gravity. Here we report an analysis of archival data that reveals an observational correlation between surface gravity and the root-mean-square brightness variations on timescales of less than eight hours for stars with temperatures ...

  12. Brightness, coherence, and propagation characteristics of synchrotron radiation

    International Nuclear Information System (INIS)

    A formalism is presented by means of which the propagation and imaging characteristics of synchrotron radiation can be studied, taking into account the effects of diffraction, electron beam emittance, and the transverse and longitudinal extent of the source. An important quantity in this approach is the Wigner distribution of the electric fields, which can be interpreted as a phase-space distribution of photon flux, and thus can be identified with the brightness. When integrated over the angular variables, the brightness becomes the intensity distribution in the spatial variables and when integrated over the spatial variables, it becomes the intensity distribution in angular variables. The brightness so defined transforms through a general optical medium in exactly the same way as in the case of a collection of geometric rays. Finally, the brightness of different electrons adds in a simple way. Optical characteristics of various synchrotron radiation sources - bending magnets, wigglers and undulators, are analyzed using this formalism

  13. Ultra High Brightness/Low Cost Fiber Coupled Packaging Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The focus of the proposed effort is maximizing the brightness of fiber coupled laser diode pump sources at a minimum cost. The specific innovation proposed is to...

  14. Visible Color and Photometry of Bright Materials on Vesta

    Science.gov (United States)

    Schroder, S. E.; Li, J. Y.; Mittlefehldt, D. W.; Pieters, C. M.; De Sanctis, M. C.; Hiesinger, H.; Blewett, D. T.; Russell, C. T.; Raymond, C. A.; Keller, H. U.

    2012-01-01

    The Dawn Framing Camera (FC) collected images of the surface of Vesta at a pixel scale of 70 m in the High Altitude Mapping Orbit (HAMO) phase through its clear and seven color filters spanning from 430 nm to 980 nm. The surface of Vesta displays a large diversity in its brightness and colors, evidently related to the diverse geology [1] and mineralogy [2]. Here we report a detailed investigation of the visible colors and photometric properties of the apparently bright materials on Vesta in order to study their origin. The global distribution and the spectroscopy of bright materials are discussed in companion papers [3, 4], and the synthesis results about the origin of Vestan bright materials are reported in [5].

  15. Are solar brightness variations faculae- or spot-dominated?

    CERN Document Server

    Shapiro, A I; Krivova, N A; Yeo, K L; Schmutz, W K

    2016-01-01

    Regular spaceborne measurements have revealed that solar brightness varies on multiple timescales, variations on timescales greater than a day being attributed to surface magnetic field. Independently, ground-based and spaceborne measurements suggest that Sun-like stars show a similar, but significantly broader pattern of photometric variability. To understand whether the broader pattern of stellar variations is consistent with the solar paradigm we assess relative contributions of faculae and spots to solar magnetically-driven brightness variability. We investigate how the solar brightness variability as well as its facular and spot contributions depend on the wavelength, timescale of variability, and position of the observer relative to the ecliptic plane. We perform calculations with the SATIRE model, which returns solar brightness with daily cadence from solar disc area coverages of various magnetic features. Moving the observer away from the ecliptic plane increases the amplitude of 11-year variability a...

  16. Fluorescent minerals, a review

    Science.gov (United States)

    Modreski, P.J.; Aumente-Modreski, R.

    1996-01-01

    Fluorescent minerals are more than just an attractive novelty, and collecting them is a speciality for thousands of individuals who appreciate their beauty, rarity, and scientific value. Fluorescent properties can be used as an aid to mineral identification, locality determination, and distinction between natural and synthetic gemstones. This article gives an overview of those aspects of fluorescence that are of most interest to collectors, hobbyists, and mineralogists. -from Authors

  17. Millimeter-wave brightness temperatures of military vehicles

    Science.gov (United States)

    Nemarich, Joseph; Cassidy, Thomas W.; Shiner, R.; Agravante, Hiroshi H.; Dixon, David; Moffa, Philip; Quon, Bill H.; Yujiri, Larry; Dahlstrom, R.

    1999-07-01

    Millimeter wave (MMW) radiometers operating at 97 and 140 GHz were used to obtain passive MMW images and brightness temperatures of military vehicles at various altitudes and depression angles. The line-scanning radiometer system used for the measurements is described, and several passive MMW images are presented. The upper-bound MMW brightness temperatures of a number of different types of vehicles in an open area were determined and shown to have similar values at various depression angles.

  18. Night Sky Brightness and Light Pollution in Comunidad de Madrid

    OpenAIRE

    Zamorano Calvo, Jaime; Sánchez de Miguel, Alejandro; Gómez Castaño, José; Ocaña González, Francisco; Gallego Maestro, Jesús; Pila Díez, Berenice; Nievas Rosillo, Miguel; Tapia Ayuga, Carlos; Fernández Domínguez, Alberto; Pascual Ramírez, Sergio

    2013-01-01

    Preliminary results of a study of the night sky background brightness around the city of Madrid using Sky Quality Meter (SQM) photometers are presented. Data-retrieval methodology includes an automatic procedure to measure from a moving vehicle which allows to speed up the data gathering. The night sky brightness, an astronomical quality parameter that accounts for luminous flux from the sky, is closely related with the light pollution. The map with the spatial distribution of the night s...

  19. Analytically derived conversion of spectral band radiance to brightness temperature

    Energy Technology Data Exchange (ETDEWEB)

    Berk, Alexander [Spectral Sciences, Inc., 44th Avenue, Burlington, MA 01803 (United States)], E-mail: lex@spectral.com

    2008-05-15

    Simple analytic expressions for brightness temperature have been derived in terms of band response function spectral moments. Accuracy measures are also derived. Application of these formulas to GOES-12 Sounder thermal infrared bands produces brightness temperature residuals between -5.0 and 2.5 mK for a 150-400 K temperature range. The magnitude of residuals for the five ASTER Radiometer thermal infrared bands over the same temperature range is less than 0.22 mK.

  20. Facial Expression Recognition using Entropy and Brightness Features

    OpenAIRE

    Khan, Rizwan Ahmed; Meyer, Alexandre; Konik, Hubert; Bouakaz, Saïda

    2011-01-01

    International audience This paper proposes a novel framework for universal facial expression recognition. The framework is based on two sets of features extracted from the face image: entropy and brightness. First, saliency maps are obtained by state-of-the-art saliency detection algorithm i.e. "frequencytuned salient region detection". Then only localized salient facial regions from saliency maps are processed to extract entropy and brightness features. To validate the performance of sali...

  1. New Low Surface Brightness Dwarf Galaxies Detected Around Nearby Spirals

    OpenAIRE

    Karachentsev, I. D.; Riepe, P.; Zilch, T.; Blauensteiner, M.; Elvov, M.; Hochleitner, P.; Hubl, B.; Kerschhuber, G.; Küppers, S.; Neyer, F.; Pölzl, R.; Remmel, P.; Schneider, O.; Sparenberg, R.; Trulson, U.

    2015-01-01

    We conduct a survey of low surface brightness (LSB) satellite galaxies around the Local Volume massive spirals using long exposures with small amateur telescopes. We identified 27 low and very low surface brightness objects around the galaxies NGC,672, 891, 1156, 2683, 3344, 4258, 4618, 4631, and 5457 situated within 10 Mpc from us, and found nothing new around NGC,2903, 3239, 4214, and 5585. Assuming that the dwarf candidates are the satellites of the neighboring luminous galaxies, their abs...

  2. WE-D-BRF-01: FEATURED PRESENTATION - Investigating Particle Track Structures Using Fluorescent Nuclear Track Detectors and Monte Carlo Simulations

    International Nuclear Information System (INIS)

    Purpose: To report on the efforts funded by the AAPM seed funding grant to develop the basis for fluorescent nuclear track detector (FNTD) based radiobiological experiments in combination with dedicated Monte Carlo simulations (MCS) on the nanometer scale. Methods: Two confocal microscopes were utilized in this study. Two FNTD samples were used to find the optimal microscope settings, one FNTD irradiated with 11.1 MeV/u Gold ions and one irradiated with 428.77 MeV/u Carbon ions. The first sample provided a brightly luminescent central track while the latter is used to test the capabilities to observe secondary electrons. MCS were performed using TOPAS beta9 version, layered on top of Geant4.9.6p02. Two sets of simulations were performed, one with the Geant4-DNA physics list and approximating the FNTDs by water, a second set using the Penelope physics list in a water-approximated FNTD and a aluminum-oxide FNTD. Results: Within the first half of the funding period, we have successfully established readout capabilities of FNTDs at our institute. Due to technical limitations, our microscope setup is significantly different from the approach implemented at the DKFZ, Germany. However, we can clearly reconstruct Carbon tracks in 3D with electron track resolution of 200 nm. A second microscope with superior readout capabilities will be tested in the second half of the funding period, we expect an improvement in signal to background ratio with the same the resolution.We have successfully simulated tracks in FNTDs. The more accurate Geant4-DNA track simulations can be used to reconstruct the track energy from the size and brightness of the observed tracks. Conclusion: We have achieved the goals set in the seed funding proposal: the setup of FNTD readout and simulation capabilities. We will work on improving the readout resolution to validate our MCS track structures down to the nanometer scales

  3. Bright-field Nanoscopy: Visualizing Nano-structures with Localized Optical Contrast Using a Conventional Microscope

    Science.gov (United States)

    Suran, Swathi; Bharadwaj, Krishna; Raghavan, Srinivasan; Varma, Manoj M.

    2016-04-01

    Most methods for optical visualization beyond the diffraction limit rely on fluorescence emission by molecular tags. Here, we report a method for visualization of nanostructures down to a few nanometers using a conventional bright-field microscope without requiring additional molecular tags such as fluorophores. The technique, Bright-field Nanoscopy, is based on the strong thickness dependent color of ultra-thin germanium on an optically thick gold film. We demonstrate the visualization of grain boundaries in chemical vapour deposited single layer graphene and the detection of single 40 nm Ag nanoparticles. We estimate a size detection limit of about 2 nm using this technique. In addition to visualizing nano-structures, this technique can be used to probe fluid phenomena at the nanoscale, such as transport through 2D membranes. We estimated the water transport rate through a 1 nm thick polymer film using this technique, as an illustration. Further, the technique can also be extended to study the transport of specific ions in the solution. It is anticipated that this technique will find use in applications ranging from single-nanoparticles resolved sensing to studying nanoscale fluid-solid interface phenomena.

  4. Rapid identification of microorganisms by intrinsic fluorescence

    Science.gov (United States)

    Bhatta, Hemant; Goldys, Ewa M.; Learmonth, Robert

    2005-03-01

    Microbial contamination has serious consequences for the industries that use fermentation processes. Common contaminants such as faster growing lactic acid bacteria or wild yeast can rapidly outnumber inoculated culture yeast and produce undesirable end products. Our study focuses on a rapid method of identification of such contaminants based on autofluorescence spectroscopy of bacterial and yeast species. Lactic acid bacteria (Lac-tobacillus casei), and yeast (Saccharomyces cerevisiae) were cultured under controlled conditions and studied for variations in their autofluorescence. We observed spectral differences in the spectral range representative of tryptophan residues of proteins, with excitation at 290 nm and emission scanned in the 300 nm - 440 nm range. Excitation scans between 240 nm and 310 nm were also performed for the emission at 340 nm. Moreover, we observed clearly pronounced differences in the excitation and emission in the visible range, with 410 nm excitation. These results demonstrate that bacterial and yeast species can be differentiated using their intrinsic fluorescence both in UV and in the visible region. The comparative spectroscopic study of selected strains of Saccharomyces yeast showed clear differences between strains. Spectrally-resolved laser scanning microscopy was carried out to link the results obtained using ensembles of cells with spectral properties of individual cells. Strongly fluorescent subpopulation were observed for all yeast strains with excitation at 405 nm. The fluorescence spectra showed variations correlated with cell brightness. The presented results demonstrate that using autofluorescence, it is possible to differentiate between yeast and lactic acid bacteria and between different yeast species.

  5. Fluorescent lighting with aluminum nitride phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Cherepy, Nerine J.; Payne, Stephen A.; Seeley, Zachary M.; Srivastava, Alok M.

    2016-05-10

    A fluorescent lamp includes a glass envelope; at least two electrodes connected to the glass envelope; mercury vapor and an inert gas within the glass envelope; and a phosphor within the glass envelope, wherein the phosphor blend includes aluminum nitride. The phosphor may be a wurtzite (hexagonal) crystalline structure Al.sub.(1-x)M.sub.xN phosphor, where M may be drawn from beryllium, magnesium, calcium, strontium, barium, zinc, scandium, yttrium, lanthanum, cerium, praseodymium, europium, gadolinium, terbium, ytterbium, bismuth, manganese, silicon, germanium, tin, boron, or gallium is synthesized to include dopants to control its luminescence under ultraviolet excitation. The disclosed Al.sub.(1-x)M.sub.xN:Mn phosphor provides bright orange-red emission, comparable in efficiency and spectrum to that of the standard orange-red phosphor used in fluorescent lighting, Y.sub.2O.sub.3:Eu. Furthermore, it offers excellent lumen maintenance in a fluorescent lamp, and does not utilize "critical rare earths," minimizing sensitivity to fluctuating market prices for the rare earth elements.

  6. Synthesizing SMOS Zero-Baselines with Aquarius Brightness Temperature Simulator

    Science.gov (United States)

    Colliander, A.; Dinnat, E.; Le Vine, D.; Kainulainen, J.

    2012-01-01

    SMOS [1] and Aquarius [2] are ESA and NASA missions, respectively, to make L-band measurements from the Low Earth Orbit. SMOS makes passive measurements whereas Aquarius measures both passive and active. SMOS was launched in November 2009 and Aquarius in June 2011.The scientific objectives of the missions are overlapping: both missions aim at mapping the global Sea Surface Salinity (SSS). Additionally, SMOS mission produces soil moisture product (however, Aquarius data will eventually be used for retrieving soil moisture too). The consistency of the brightness temperature observations made by the two instruments is essential for long-term studies of SSS and soil moisture. For resolving the consistency, the calibration of the instruments is the key. The basis of the SMOS brightness temperature level is the measurements performed with the so-called zero-baselines [3]; SMOS employs an interferometric measurement technique which forms a brightness temperature image from several baselines constructed by combination of multiple receivers in an array; zero-length baseline defines the overall brightness temperature level. The basis of the Aquarius brightness temperature level is resolved from the brightness temperature simulator combined with ancillary data such as antenna patterns and environmental models [4]. Consistency between the SMOS zero-baseline measurements and the simulator output would provide a robust basis for establishing the overall comparability of the missions.

  7. Evolution of Bright Screening-photovoltaic Spatial Optical Solitons

    Institute of Scientific and Technical Information of China (English)

    LIU Jinsong

    2001-01-01

    A numerical analysis of the dynamical evolution of bright screening-photovoltaic (SP) spatial solitons in biased photovoltaic-photorefractive materials in the case of neglecting the material loss and the diffusion is presented. When an incident optical beam is a bright SP soliton, the beam propagates along a linear path with its shape kept unchanged. When the incident optical beam is slightly different from a bright SP soliton, the beam reshapes itself and tries to evolve into a bright SP soliton after a short distance. However, when the incident optical beam is significantly different from a SP bright soliton, the beam cannot evolve into a stable bright SP soliton, and tends to experience periodic compression and expansion. For a low-intensity input beam, the wave experiences a periodic process of compression first and then expansion during the initial part of the cycle. For a high-intensity input beam, however, the wave will initially diffract and then experiences compression during the cycle.

  8. Live-cell multiphoton fluorescence correlation spectroscopy with an improved large Stokes shift fluorescent protein

    Science.gov (United States)

    Guan, Yinghua; Meurer, Matthias; Raghavan, Sarada; Rebane, Aleksander; Lindquist, Jake R.; Santos, Sofia; Kats, Ilia; Davidson, Michael W.; Mazitschek, Ralph; Hughes, Thomas E.; Drobizhev, Mikhail; Knop, Michael; Shah, Jagesh V.

    2015-01-01

    We report an improved variant of mKeima, a monomeric long Stokes shift red fluorescent protein, hmKeima8.5. The increased intracellular brightness and large Stokes shift (∼180 nm) make it an excellent partner with teal fluorescent protein (mTFP1) for multiphoton, multicolor applications. Excitation of this pair by a single multiphoton excitation wavelength (MPE, 850 nm) yields well-separable emission peaks (∼120-nm separation). Using this pair, we measure homo- and hetero-oligomerization interactions in living cells via multiphoton excitation fluorescence correlation spectroscopy (MPE-FCS). Using tandem dimer proteins and small-molecule inducible dimerization domains, we demonstrate robust and quantitative detection of intracellular protein–protein interactions. We also use MPE-FCCS to detect drug–protein interactions in the intracellular environment using a Coumarin 343 (C343)-conjugated drug and hmKeima8.5 as a fluorescence pair. The mTFP1/hmKeima8.5 and C343/hmKeima8.5 combinations, together with our calibration constructs, provide a practical and broadly applicable toolbox for the investigation of molecular interactions in the cytoplasm of living cells. PMID:25877871

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

    Directory of Open Access Journals (Sweden)

    Shuo Wang

    2013-09-01

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

  10. Two-photon directed evolution of green fluorescent proteins

    Science.gov (United States)

    Stoltzfus, Caleb R.; Barnett, Lauren M.; Drobizhev, Mikhail; Wicks, Geoffrey; Mikhaylov, Alexander; Hughes, Thomas E.; Rebane, Aleksander

    2015-07-01

    Directed evolution has been used extensively to improve the properties of a variety of fluorescent proteins (FPs). Evolutionary strategies, however, have not yet been used to improve the two-photon absorption (2PA) properties of a fluorescent protein, properties that are important for two-photon imaging in living tissues, including the brain. Here we demonstrate a technique for quantitatively screening the two-photon excited fluorescence (2PEF) efficiency and 2PA cross section of tens of thousands of mutant FPs expressed in E. coli colonies. We use this procedure to move EGFP through three rounds of two-photon directed evolution leading to new variants showing up to a 50% enhancement in peak 2PA cross section and brightness within the near-IR tissue transparency wavelength range.

  11. Out of the darkness and into the light: bright field in situ hybridisation for delineation of ERBB2 (HER2) status in breast carcinoma

    OpenAIRE

    Gruver, Aaron M; Peerwani, Ziad; Tubbs, Raymond R.

    2010-01-01

    Assessment of ERBB2 (HER2) status in breast carcinomas has become critical in determining response to the humanised monoclonal antibody trastuzumab. The current joint College of American Pathologists and the American Society of Clinical Oncology guidelines for the evaluation of HER2 status in breast carcinoma involve testing by immunohistochemistry and fluorescence in situ hybridisation (FISH). However, neither of these modalities is without limitations. Novel bright field in situ hybridisati...

  12. Giant Amplification of Photoswitching by a Few Photons in Fluorescent Photochromic Organic Nanoparticles.

    Science.gov (United States)

    Su, Jia; Fukaminato, Tuyoshi; Placial, Jean-Pierre; Onodera, Tsunenobu; Suzuki, Ryuju; Oikawa, Hidetoshi; Brosseau, Arnaud; Brisset, François; Pansu, Robert; Nakatani, Keitaro; Métivier, Rémi

    2016-03-01

    Controlling or switching the optical signal from a large collection of molecules with the minimum of photons represents an extremely attractive concept. Promising fundamental and practical applications may be derived from such a photon-saving principle. With this aim in mind, we have prepared fluorescent photochromic organic nanoparticles (NPs), showing bright red emission, complete ON-OFF contrast with full reversibility, and excellent fatigue resistance. Most interestingly, upon successive UV and visible light irradiation, the NPs exhibit a complete fluorescence quenching and recovery at very low photochromic conversion levels (photochromic molecule. This "giant amplification of fluorescence photoswitching" originates from efficient intermolecular energy-transfer processes within the NPs. PMID:26821998

  13. Seoul National University Bright Quasar Survey in Optical (SNUQSO). II. Discovery of 40 Bright Quasars Near the Galactic Plane

    CERN Document Server

    Im, Myungshin; Cho, Yunseok; Choi, Changsu; Ko, Jongwan; Song, Mimi

    2008-01-01

    We report the discovery of 40 bright quasars and active galactic nuclei (AGNs) at low Galactic latitude (b<20deg). The low Galactic latitude region has been considered a place to avoid when searching for extragalactic sources, because of the high Galactic extinction, as well as a large number of stars contaminating the sample selection. Bright quasars (R<~17) suffer more from such difficulties because they look like bright stars, which are numerous at low b, yet their surface number density is very low. In order to find quasars in this region of the sky less explored for extragalactic sources, we have started a survey of low Galactic latitude bright quasars as a part of the Seoul National University Quasar Survey in Optical (SNUQSO). Quasar candidates have been selected from radio and near-infrared (NIR) data. Out of 88 targets, we identify 29 bright quasars/AGNs around the antigalactic center, and 11 bright quasars/AGNs in the outskirts of the Galactic center, from two observing runs in 2006 at the Boh...

  14. Acri-2,7-Py, a bright red-emitting DNA probe identified through screening of a distyryl dye library.

    Science.gov (United States)

    Naud-Martin, Delphine; Martin-Benlloch, Xavier; Poyer, Florent; Mahuteau-Betzer, Florence; Teulade-Fichou, Marie-Paule

    2014-02-01

    The identification of DNA sensors is still a challenge since no DNA probe possesses all the photophysical properties required for live-cell imaging: high fluorescence yield, red emission, permeability, no photobleaching and no cytotoxicity. We describe the preparation of a distyryl dye library and its evaluation on a panel of nucleic acids with various structures (duplex DNA, quadruplex DNA and RNA). The screening involved measuring the modification of the fluorescence properties of the dyes with or without nucleic acids on a microplate reader, and allowed the identification of selective quadruplex DNA ligands with good affinities. Using this screening method we discovered a new bright red-emitting DNA stain, Acri-2,7-Py, for fixed cells. In living cells, the staining was not nuclear and photodamage generated through illumination induced cellular death. These processes require further studies to determine the relevance of Acri-2,7-Py in photodynamic therapy. PMID:24323895

  15. 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

  16. Membranes and Fluorescence microscopy

    DEFF Research Database (Denmark)

    Bagatolli, Luis

    2009-01-01

    Fluorescence spectroscopy-based techniques using conventional fluorimeters have been extensively applied since the late 1960s to study different aspects of membrane-related phenomena, i.e., mainly relating to lipid-lipid and lipid-protein (peptide) interactions. Even though fluorescence...

  17. A green fluorescent protein with photoswitchable emission from the deep sea.

    Directory of Open Access Journals (Sweden)

    Alexander Vogt

    Full Text Available A colorful variety of fluorescent proteins (FPs from marine invertebrates are utilized as genetically encoded markers for live cell imaging. The increased demand for advanced imaging techniques drives a continuous search for FPs with new and improved properties. Many useful FPs have been isolated from species adapted to sun-flooded habitats such as tropical coral reefs. It has yet remained unknown if species expressing green fluorescent protein (GFP-like proteins also exist in the darkness of the deep sea. Using a submarine-based and -operated fluorescence detection system in the Gulf of Mexico, we discovered ceriantharians emitting bright green fluorescence in depths between 500 and 600 m and identified a GFP, named cerFP505, with bright fluorescence emission peaking at 505 nm. Spectroscopic studies showed that approximately 15% of the protein bulk feature reversible ON/OFF photoswitching that can be induced by alternating irradiation with blue und near-UV light. Despite being derived from an animal adapted to essentially complete darkness and low temperatures, cerFP505 maturation in living mammalian cells at 37 degrees C, its brightness and photostability are comparable to those of EGFP and cmFP512 from shallow water species. Therefore, our findings disclose the deep sea as a potential source of GFP-like molecular marker proteins.

  18. Comparison of measured brightness temperatures from SMOS with modelled ones from ORCHIDEE and H-TESSEL over the Iberian Peninsula

    Science.gov (United States)

    Barella-Ortiz, A.; Polcher, J.; de Rosnay, P.; Piles, M.; Gelati, E.

    2015-12-01

    L-Band radiometry is considered to be one of the most suitable techniques to estimate surface soil moisture by means of remote sensing. Brightness temperatures are key in this process, as they are the main input in the retrieval algorithm. The work exposed compares brightness temperatures measured by the Soil Moisture and Ocean Salinity (SMOS) mission to two different sets of modelled ones, over the Iberian Peninsula from 2010 to 2012. The latter were estimated using a radiative transfer model and state variables from two land surface models: (i) ORganising Carbon and Hydrology In Dynamic EcosystEms (ORCHIDEE) and (ii) Hydrology - Tiled ECMWF Scheme for Surface Exchanges over Land (H-TESSEL). The radiative transfer model used is the Community Microwave Emission Model (CMEM). A good agreement in the temporal evolution of measured and modelled brightness temperatures is observed. However, their spatial structures are not consistent between them. An Empirical Orthogonal Function analysis of the brightness temperature's error identifies a dominant structure over the South-West of the Iberian Peninsula which evolves during the year and is maximum in Fall and Winter. Hypotheses concerning forcing induced biases and assumptions made in the radiative transfer model are analysed to explain this inconsistency, but no candidate is found to be responsible for it at the moment. Further hypotheses are proposed at the end of the paper.

  19. Detecting clandestine material with nuclear resonance fluorescence

    Science.gov (United States)

    Pruet, J.; McNabb, D. P.; Hagmann, C. A.; Hartemann, F. V.; Barty, C. P. J.

    2006-06-01

    We study the performance of a class of interrogation systems that exploit nuclear resonance fluorescence (NRF) to detect specific isotopes. In these systems the presence of a particular nuclide is inferred by observing the preferential attenuation of photons that strongly excite an electromagnetic transition in that nuclide. Estimates for the false positive/negative error rates, radiological dose, and detection sensitivity associated with discovering clandestine material embedded in cargo are presented. The relation between performance of the detection system and properties of the beam of interrogating photons is also considered. Bright gamma-ray sources with fine energy and angular resolution, such as those based on Thomson upscattering of laser light, are found to be associated with uniquely low radiological dose, scan times, and error rates. For this reason a consideration of NRF-based interrogation systems may provide impetus for efforts in light source development for applications related to national security and industry.

  20. Bright, water-soluble CeF3 photo-, cathodo-, and X-ray luminescent nanoparticles

    International Nuclear Information System (INIS)

    Bright, water-soluble CeF3 nanoparticles with small size and narrow size distribution have been synthesized using a simple co-precipitation method without any ligands. Size control of nanoparticles from 13 ± 2 to 9 ± 2 nm was achieved by varying the reaction time. Colloidal properties have been found to vary with pH and, independently, with dilution. The photoluminescence of the as-synthesized nanoparticles shows a highly photostable UV/Visible fluorescence band due to allowed 5d–4f transitions, also observed in the X-ray luminescence spectrum. This band is suitable for X-ray excitation of a range of photosensitizers. The photoluminescence quantum yield of nanoparticles was also determined to be 31 %. Using the measured fluorescence decay time of 25 ns, the radiative lifetime of Ce in CeF3 was found to be 80.6 ns. Both photoluminescence and cathodoluminescence emission are affected by the reaction time and measurement temperature. Electron-beam-induced defect annealing is also observed

  1. Night sky brightness at San Pedro Martir Observatory

    CERN Document Server

    Plauchu-Frayn, I; Colorado, E; Herrera, J; Cordova, A; Cesena, U; Avila, F

    2016-01-01

    We present optical UBVRI zenith night sky brightness measurements collected on eighteen nights during 2013--2016 and SQM measurements obtained daily over twenty months during 2014--2016 at the Observatorio Astronomico Nacional on the Sierra San Pedro Martir (OAN-SPM) in Mexico. The UBVRI data is based upon CCD images obtained with the 0.84m and 2.12m telescopes, while the SQM data is obtained with a high-sensitivity, low-cost photometer. The typical moonless night sky brightness at zenith averaged over the whole period is U = 22.68, B = 23.10, V = 21.84, R = 21.04, I = 19.36, and SQM = 21.88 mag/square arcsec, once corrected for zodiacal light. We find no seasonal variation of the night sky brightness measured with the SQM. The typical night sky brightness values found at OAN-SPM are similar to those reported for other astronomical dark sites at a similar phase of the solar cycle. We find a trend of decreasing night sky brightness with decreasing solar activity during period of the observations. This trend im...

  2. The night sky brightness at Potsdam-Babelsberg

    CERN Document Server

    Puschnig, Johannes; Posch, Thomas; Schwarz, Robert

    2013-01-01

    We analyze the results of a 2 years (2011--2012) time series of night sky photometry performed at the Leibniz Institute for Astrophysics in Potsdam (AIP). This observatory is located on top of a hill ("Babelsberg"), 22\\,km to the southwest of the center of Berlin. The measurements have been performed with a Unihedron Sky Quality Meter. We find night sky brightness values ranging from 16.5 to 20.3 mag$_{\\rm SQM}$ arcsec$^{-2}$; the latter (best) value corresponds to 4.7 times the natural zenithal night sky brightness. We discuss the influence of clouds, of the Moon and other factors on the night sky brightness. With respect to the influence of the Moon, it turns out that Potsdam-Babelsberg, despite its proximity to Berlin, still shows a circalunar periodicity of the night sky brightness, although it is much weaker than naturally. The light-pollution-enhancing effect of clouds dominates the night sky brightness by far. Overcast nights with light pollution (up to 16.5 mag$_{\\rm SQM}$ arcsec$^{-2}$) are brighter ...

  3. PROFFIT: Analysis of X-ray surface-brightness profiles

    Science.gov (United States)

    Eckert, Dominique

    2016-08-01

    PROFFIT analyzes X-ray surface-brightness profiles for data from any X-ray instrument. It can extract surface-brightness profiles in circular or elliptical annuli, using constant or logarithmic bin size, from the image centroid, the surface-brightness peak, or any user-given center, and provides surface-brightness profiles in any circular or elliptical sectors. It offers background map support to extract background profiles, can excise areas using SAO DS9-compatible (ascl:0003.002) region files to exclude point sources, provides fitting with a number of built-in models, including the popular beta model, double beta, cusp beta, power law, and projected broken power law, uses chi-squared or C statistic, and can fit on the surface-brightness or counts data. It has a command-line interface similar to HEASOFT’s XSPEC (ascl:9910.005) package, provides interactive help with a description of all the commands, and results can be saved in FITS, ROOT or TXT format.

  4. Bright artificial light subsensitizes a central muscarinic mechanism.

    Science.gov (United States)

    Dilsaver, S C; Majchrzak, M J

    1987-12-14

    Supersensitivity of a muscarinic mechanism is implicated in the pathophysiology of depression. Bright artificial light is efficacious in the treatment of Seasonal Affective Disorder (SAD). We studied the effect of constant bright light (11,500 lux) on the sensitivity of adult, male rats to oxotremorine, 1.5 mg/kg ip, using a repeated measures design. Oxotremorine challenges were proceeded by the injection of methylscopolamine, 1 mg/kg ip, by 30 minutes. Temperature was telemetrically measured every 10 minutes for 120 minutes starting 10 minutes after the injection of oxotremorine. Prior to and after 7 continuous days of exposure to bright light, the sample exhibited a hypothermic response of 2.50 +/- 0.48 degrees C (mean +/- SEM) and 0.29 +/- 0.31 degrees C (mean +/- SEM), respectively (p less than 0.0014). All 7 animals exhibited blunting to the thermic response to oxotremorine. Bright light also blocked the capacity of amitriptyline to supersensitize a central muscarinic mechanism. Exposure to light at an intensity of 300 lux for 7 days had no effect on the thermic response to oxotremorine. These data are consistent with the hypotheses that the biology of depression involves supersensitivity of central muscarinic mechanisms and that the effects of bright artificial light are not the consequence of shifting circadian rhythms. PMID:3695799

  5. 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.

  6. Bright and Not-So-Bright Prospects for Women in Physics in China-Beijing

    Science.gov (United States)

    Wu, Ling-An; Yang, Zhongqin; Ma, Wanyun

    2009-04-01

    Science in China-Beijing is enjoying a healthy increase in funding year by year, so the prospects for physicists are also bright. However, employment discrimination against women, formerly unthinkable, is becoming more and more explicit as the country evolves toward a market economy. Some recruitment notices bluntly state that only men will be considered, or impose restrictions upon potential female candidates. Female associate professors in many institutions are forced to retire at age 55, compared with 60 for men. This double-pinching discrimination against both younger and older women threatens to lead to a "pincer" effect, more serious than the "scissors" effect. Indeed, the ratio of senior-level women physicists in general has dropped significantly in recent years in China. Ironically, the number of female students applying for graduate studies is on the rise, as it is becoming increasingly difficult for them to compete with men in the job market with just an undergraduate degree. The Chinese Physical Society has made certain efforts to promote the image of women physicists, but it will take time and effort to reverse the trend.

  7. Influence of Type of Electric Bright Light on the Attraction of the African Giant Water Bug, Lethocerus indicus (Hemiptera: Belostomatidae

    Directory of Open Access Journals (Sweden)

    Luke Chinaru Nwosu

    2012-01-01

    Full Text Available This study investigated the influence of type of electric bright light (produced by fluorescent light tube and incandescent light bulb on the attraction of the African giant water bug, Lethocerus indicus (Hemiptera: Belostomatidae. Four fluorescent light tubes of 15 watts each, producing white-coloured light and four incandescent light bulbs of 60 watts each, producing yellow-coloured light, but both producing the same amount of light, were varied and used for the experiments. Collections of bugs at experimental house were done at night between the hours of 8.30 pm and 12 mid-night on daily basis for a period of four months per experiment in the years 2008 and 2009. Lethocerus indicus whose presence in any environment has certain implications was the predominant belostomatid bug in the area. Use of incandescent light bulbs in 2009 significantly attracted more Lethocerus indicus 103 (74.6% than use of fluorescent light tubes 35 (25.41% in 2008 [4.92=0.0001]. However, bug’s attraction to light source was not found sex dependent [>0.05; (>0.18=0.4286 and >0.28=0.3897]. Therefore, this study recommends the use of fluorescent light by households, campgrounds, and other recreational centres that are potentially exposed to the nuisance of the giant water bugs. Otherwise, incandescent light bulbs should be used when it is desired to attract the presence of these aquatic bugs either for food or scientific studies.

  8. Fluorescence spectroscopy for wastewater monitoring: A review.

    Science.gov (United States)

    Carstea, Elfrida M; Bridgeman, John; Baker, Andy; Reynolds, Darren M

    2016-05-15

    Wastewater quality is usually assessed using physical, chemical and microbiological tests, which are not suitable for online monitoring, provide unreliable results, or use hazardous chemicals. Hence, there is an urgent need to find a rapid and effective method for the evaluation of water quality in natural and engineered systems and for providing an early warning of pollution events. Fluorescence spectroscopy has been shown to be a valuable technique to characterize and monitor wastewater in surface waters for tracking sources of pollution, and in treatment works for process control and optimization. This paper reviews the current progress in applying fluorescence to assess wastewater quality. Studies have shown that, in general, wastewater presents higher fluorescence intensity compared to natural waters for the components associated with peak T (living and dead cellular material and their exudates) and peak C (microbially reprocessed organic matter). Furthermore, peak T fluorescence is significantly reduced after the biological treatment process and peak C is almost completely removed after the chlorination and reverse osmosis stages. Thus, simple fluorometers with appropriate wavelength selectivity, particularly for peaks T and C could be used for online monitoring in wastewater treatment works. This review also shows that care should be taken in any attempt to identify wastewater pollution sources due to potential overlapping fluorophores. Correlations between fluorescence intensity and water quality parameters such as biochemical oxygen demand (BOD) and total organic carbon (TOC) have been developed and dilution of samples, typically up to ×10, has been shown to be useful to limit inner filter effect. It has been concluded that the following research gaps need to be filled: lack of studies on the on-line application of fluorescence spectroscopy in wastewater treatment works and lack of data processing tools suitable for rapid correction and extraction of

  9. 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.

  10. Low surface brightness galaxies in the cluster A1367

    International Nuclear Information System (INIS)

    We have obtained deep CCD frames of apparently blank regions of sky in the hope of detecting very low surface brightness (LSB) objects in the cluster A1367. We discuss our data reduction, and image detection and selection techniques. If the galaxies detected are actually cluster members then they are dwarfs and the conclusions of a previous paper on the Fornax cluster are essentially confirmed. One area of variance is that the lowest surface brightness galaxies do not appear to be preferentially concentrated towards the cluster centre. This can be explained by there being a much larger density of dwarf galaxies over this bright galaxy-rich region of the universe. We find over our small area approximately four times as many LSB galaxies as would be expected from our Fornax data. We speculate on the possible origin and likely intensity of intergalactic light within clusters. (author)

  11. Low dimensional neutron moderators for enhanced source brightness

    DEFF Research Database (Denmark)

    Mezei, Ferenc; Zanini, Luca; Takibayev, Alan;

    2014-01-01

    In a recent numerical optimization study we have found that liquid para-hydrogen coupled cold neutron moderators deliver 3–5 times higher cold neutron brightness at a spallation neutron source if they take the form of a flat, quasi 2-dimensional disc, in contrast to the conventional more voluminous...... cold neutrons. This model leads to the conclusions that the optimal shape for high brightness para-hydrogen neutron moderators is the quasi 1-dimensional tube and these low dimensional moderators can also deliver much enhanced cold neutron brightness in fission reactor neutron sources, compared to the...... shapes used by now. In the present paper we describe a simple theoretical explanation of this unexpected behavior, which is based on the large difference in para-hydrogen between the values of the scattering mean free path for thermal neutrons (in the range of 1 cm) and its much larger equivalent for...

  12. Fluorescent property of indocyanine green (ICG) rubber ring using LED and laser light sources.

    Science.gov (United States)

    Hong, Nha Young; Kim, Hong Rae; Lee, Hyun Min; Sohn, Dae Kyung; Kim, Kwang Gi

    2016-05-01

    Fluorescent properties of ICG depends on solvent. Fluorescent characteristics of ICG rubber rings and optimized detection system condition were identified. The fluorescent rubber rings are produced by drying mixture of ICG solution and liquid rubber. LED and laser light sources were used to test differences between them. Other variables are ICG molar concentration (100, 80, 60, 40, 20, 10μM), excitation light spectrum (740, 760, 785nm) and angle of view (0~80°). We observed that ICG ring emitted fluorescence at longer wavelength than in blood and aqueous state. Observation angle between 0 and 50 provided similar brightness of images, while others are significantly less luminous. Excitation light between 740~760nm ensured non-overlapping spectrums of excitation light and fluorescence emission. PMID:27280060

  13. Effects of Bright Light Treatment on Psychomotor Speed in Athletes

    Directory of Open Access Journals (Sweden)

    MikkoPaavoTulppo

    2014-05-01

    Full Text Available Purpose: A recent study suggests that transcranial brain targeted light treatment via ear canals may have physiological effects on brain function studied by functional magnetic resonance imaging (fMRI techniques in humans. We tested the hypothesis that bright light treatment could improve psychomotor speed in professional ice hockey players. Methods: Psychomotor speed tests with audio and visual warning signals were administered to a Finnish National Ice Hockey League team before and after 24 days of transcranial bright light or sham treatment. The treatments were given during seasonal darkness in the Oulu region (latitude 65 degrees north when the strain on the players was also very high (10 matches during 24 days. A daily 12-min dose of bright light or sham (n = 11 for both treatment was given every morning between 8–12 am at home with a transcranial bright light device. Mean reaction time and motor time were analyzed separately for both psychomotor tests. Analysis of variance for repeated measures adjusted for age was performed. Results: Time x group interaction for motor time with a visual warning signal was p = 0.024 after adjustment for age. In Bonferroni post-hoc analysis, motor time with a visual warning signal decreased in the bright light treatment group from 127 ± 43 to 94 ± 26 ms (p = 0.024 but did not change significantly in the sham group 121 ± 23 vs. 110 ± 32 ms (p = 0.308. Reaction time with a visual signal did not change in either group. Reaction or motor time with an audio warning signal did not change in either the treatment or sham group. Conclusion: Psychomotor speed, particularly motor time with a visual warning signal, improves after transcranial bright light treatment in professional ice-hockey players during the competition season in the dark time of the year.

  14. The possible origin of facular brightness in the solar atmosphere

    Science.gov (United States)

    Kostik, R.; Khomenko, E.

    2016-05-01

    This paper studies the dependence of the Ca ii H line core brightness on the strength and inclination of the photospheric magnetic field, and on the parameters of convective and wave motions in a facular region at the center of the solar disc. We use three simultaneous data sets that were obtained at the German Vacuum Tower Telescope (Observatorio del Teide, Tenerife): (1) spectra of Ba ii 4554 Å line, registered with the instrument TESOS to measure the variations of intensity and velocity through the photosphere up to the temperature minimum; (2) spectropolarimetric data in Fe i 1.56 μm lines (registered with the instrument TIP II) to measure photospheric magnetic fields; (3) filtergrams in Ca ii H that give information about brightness fluctuations in the chromosphere. The results show that the Ca ii H brightness in the facula strongly depends on the power of waves with periods in the 5-min range, which propagate upwards, and also on the phase shift between velocity oscillations at the bottom photosphere and around the temperature minimum height that is measured from Ba ii line. The Ca ii H brightness is maximum at locations where the phase shift between temperature and velocity oscillations lies within 0°-100°. There is an indirect influence of convective motions on the Ca ii H brightness. The higher the amplitude of convective velocities is and the greater the height is where they change their direction of motion, the brighter the facula. In summary, our results lead to conclusions that facular regions appear bright not only because of the Wilson depression in magnetic structures, but also owing to real heating.

  15. Remote sensing vegetation status by laser-induced fluorescence

    International Nuclear Information System (INIS)

    In November 1989 the EUREKA project LASFLEUR (EU 380) started as an European research effort to investigate the future application of far-field laser-induced plant fluorescence for synoptic, airborne environmental monitoring of vegetation. This report includes a brief introduction in a theoretically approach for the laser-induced fluorescence signals of leaves and their spectral and radiometric behaviour. In addition, a detailed description of the design and realization of the second generation of the far-field fluorescence lidar (DLidaR-2) is given with special regard to the optical and electronical setup, followed by a short explanation of the data processing. The main objectives of the far field measurements are to demonstrate the link between laser-induced fluorescence data and plant physiology and to show the reliability of remote single shot lidar measurements. The data sets include the typical daily cycles of the fluorescence for different global irradiation. As expected from biophysical models, the remotely sensed chlorophyll fluorescence is highly correlated with the carbon fixation rate, while the fluorescence ratio F685 / F730 is only dependent on the chlorophyll concentration. Drought stress measurement of evergreen oaks Quercus pubescens confirm the findings of healthy plants with regard to the fluorescence ratio F685 / F730 while the fluorescence signals of stressed plants show a different behavior than nonstressed plants. Additionally, the corresponding physiological data (porometer and PAM data) are presented. (author)

  16. Absolute brightness temperature measurements at 2.1-mm wavelength

    Science.gov (United States)

    Ulich, B. L.

    1974-01-01

    Absolute measurements of the brightness temperatures of the Sun, new Moon, Venus, Mars, Jupiter, Saturn, and Uranus, and of the flux density of DR21 at 2.1-mm wavelength are reported. Relative measurements at 3.5-mm wavelength are also preented which resolve the absolute calibration discrepancy between The University of Texas 16-ft radio telescope and the Aerospace Corporation 15-ft antenna. The use of the bright planets and DR21 as absolute calibration sources at millimeter wavelengths is discussed in the light of recent observations.

  17. High-brightness displays in integrated weapon sight systems

    Science.gov (United States)

    Edwards, Tim; Hogan, Tim

    2014-06-01

    In the past several years Kopin has demonstrated the ability to provide ultra-high brightness, low power display solutions in VGA, SVGA, SXGA and 2k x 2k display formats. This paper will review various approaches for integrating high brightness overlay displays with existing direct view rifle sights and augmenting their precision aiming and targeting capability. Examples of overlay display systems solutions will be presented and discussed. This paper will review significant capability enhancements that are possible when augmenting the real-world as seen through a rifle sight with other soldier system equipment including laser range finders, ballistic computers and sensor systems.

  18. Fluorescent filtered electrophosphorescence

    Science.gov (United States)

    Forrest, Stephen R.; Sun, Yiru; Giebink, Noel; Thompson, Mark E.

    2009-01-06

    The present invention relates to organic light emitting devices (OLEDs), and more specifically to OLEDS that emit light using a combination of fluorescent emitters and phosphorescent emitters for the efficient utilization of all of the electrically generated excitons.

  19. The Physics and Applications of High Brightness Beams: Working Group A Summary on High Brightness Beam Production

    International Nuclear Information System (INIS)

    Working group A was devoted to high brightness beam production and characterization. The presentations and discussions could be categorized as cathode physics, new photoinjector designs, computational modeling of high brightness beams, and new experimental methods and results. Several novel injector and cathode designs were presented. However, a standard 1.5 cell rf photoinjector is still the most common source for high brightness beams. New experimental results and techniques were presented and thoroughly discussed. The brightest beam produced in a rf photoinjector published at the time of the workshop is approximately 2 1014 A/(m-rad)2 at Sumitomo Heavy Industries in Japan with 1 nC of charge, a 9 ps FWHM long laser pulse and a normalized transverse emittance of 1.2 pm. The emittance was achieved by utilizing a temporally flat laser pulse which decreased the emittance by an estimated factor of 2 from the beam produced with a Gaussian pulse shape with an identical pulse length

  20. Fluorescence and cofluorescence enhancement of Tb(Ⅲ) complexes with pyromellitic acid by M (M =Gd,La,Ca,and Sr ions)

    Institute of Scientific and Technical Information of China (English)

    WANG Zhengxiang; CHEN Hong; SHU Wangen; ZHAO Dongbai; ZHOU Zhongcheng

    2004-01-01

    Fluorescence and cofluorescence properties of Tb(Ⅲ) solid complexes were studied using pyromellitic acid (PMA) as ligand and fluorescence inert ions as doping elements. The cofluorescence enhancement, a result of ligand sensitized fluorescence, was observed in Tb(Ⅲ) solid complexes doped with fluorescent inert ions La(Ⅲ), Gd(Ⅲ), Ca(Ⅲ), and Sr(Ⅲ). The effect of the type and content of doping elements on fluorescence enhancement was studied, and optimum conditions were determined. The results show that Gd (La, Ca, Sr) has clear cofluorescence effect in solid complex Tb-M-PMA system, and in present work, rare earth complex fluorescent powder that emits bright green fluorescence at ultraviolet excitation was obtained, which had potential application as fluorescent anti-counterfeit ink.

  1. Synchrotron radiation induced fluorescence spectroscopy of gas phase molecules

    OpenAIRE

    Álvarez Ruiz, Jesús

    2004-01-01

    A new experimental set-up for gas phase fluorescence studies using synchrotron radiation has been designed and constructed to perform simultaneously total and dispersed fluorescence measurements. Neutral photodissociation of CO has been investigated after excitation with 19-26 eV photons. Fluorescence from 3p 3P, 3p 3S and 3p 1D excited states in carbon was recorded and interpreted by ab initio calculations. The population and dissociation of states belonging to the C and D Rydberg series in ...

  2. Color-stable, reduced efficiency roll-off hybrid white organic light emitting diodes with ultra high brightness

    International Nuclear Information System (INIS)

    High-brightness and color-stable two-wavelength hybrid white organic light emitting diodes (HWOLEDs) with the configuration of indium tin oxide (ITO)/ N, N, N', N'-tetrakis(4-methoxyphenyl)-benzidine (MeO-TPD): tetrafluoro-tetracyanoqino dimethane (F4-TCNQ)/N,N'-di(naphthalene-1-yl)-N,N'-diphenyl-benzidine (NPB)/4,4-N,N-dicarbazolebiphenyl (CBP): iridium (III) diazine complexes (MPPZ)2Ir(acac)/NPB/2-methyl-9,10-di(2-naphthyl)anthracene (MADN): p-bis(p-N,N-di-phenyl-aminostyryl)benzene (DSA-ph)/ bis(10-hydroxybenzo[h] quinolinato)beryllium complex (Bebq2)/LiF/Al have been fabricated and characterized. The optimal brightness of the device is 69932 cd/m2 at a voltage of 13 V, and the Commission Internationale de l'Eclairage (CIE) chromaticity coordinates are almost constant during a large voltage change of 6–12 V. Furthermore, a current efficiency of 15.3 cd/A at an illumination-relevant brightness of 1000 cd/m2 is obtained, which rolls off slightly to 13.0 cd/A at an ultra high brightness of 50000 cd/m2 . We attribute this great performance to wisely selecting an appropriate spacer together with effectively utilizing the combinations of exciton-harvested orange-phosphorescence/ blue-fluorescence in the device. Undoubtedly, this is one of the most exciting results in two-wavelength HWOLEDs up to now

  3. A novel study on the mechanisms of drug release in PLGA-mPEG microspheres with fluorescent drug.

    Science.gov (United States)

    Shi, Chen; Feng, Shuibin; Liu, Ping; Liu, Xianzhe; Feng, Xiaobo; Fu, Dehao

    2016-06-01

    The purpose of this research was to proof the microspheres release mechanism by a novel method-detecting and comparing the drugs fluorescent changes on the microspheres surface. Fluorescein sodium (FS, 0.4 kDa) and fluorescein isothiocyanate-bovine serum albumin (FITC-BSA, 66.8 kDa) were employed as model drugs. FS and FITC-BSA were encapsulated into PLGA-mPEG microspheres through double emulsion evaporation method, and the drug-loaded microspheres in vitro degradation and release behaviors were evaluated by scanning electron microscope, gel permeation chromatography, confocal laser scanning microscopy (CLSM), BCA assay kit, and UV-vis spectrophotometry. FS-loaded microspheres revealed a severe initial burst release, followed by a sustained release, and we could observe a bright fluorescent on the microspheres surface during the early release period under the CLSM. The bright fluorescent gradually faded out in the later period as only 1~2% FS was remained after 14 days release. FITC-BSA-loaded microspheres revealed a typical tri-phase release profile, and we observed a weak fluorescent on the microspheres surface after the initial burst release, and the fluorescent came bright again after an obvious erosion appeared on the microspheres surface. In the later release stage, the fluorescent gradually faded out as the fast release of FITC-BSA. PMID:26980344

  4. Tumor-stem cells interactions by fluorescence imaging

    Science.gov (United States)

    Meleshina, Aleksandra V.; Cherkasova, Elena I.; Sergeeva, Ekaterina; Turchin, Ilya V.; Kiseleva, Ekaterina V.; Dashinimaev, Erdem B.; Shirmanova, Marina V.; Zagaynova, Elena V.

    2013-02-01

    Recently, great deal of interest is investigation the function of the stem cells (SC) in tumors. In this study, we studied «recipient-tumor- fluorescent stem cells » system using the methods of in vivo imaging and laser scanning microscopy (LSM). We used adipose-derived adult stem (ADAS) cells of human lentiviral transfected with the gene of fluorescent protein Turbo FP635. ADAS cells were administrated into nude mice with transplanted tumor HeLa Kyoto (human cervical carcinoma) at different stages of tumor growth (0-8 days) intravenously or into tumor. In vivo imaging was performed on the experimental setup for epi - luminescence bioimaging (IAP RAS, Nizhny Novgorod). The results of the imaging showed localization of fluorophore tagged stem cells in the spleen on day 5-9 after injection. The sensitivity of the technique may be improved by spectral separation autofluorescence and fluorescence of stem cells. We compared the results of in vivo imaging and confocal laser scanning microscopy (LSM 510 META, Carl Zeiss, Germany). Internal organs of the animals and tumor tissue were investigated. It was shown that with i.v. injection of ADAS, bright fluorescent structures with spectral characteristics corresponding to TurboFP635 protein are locally accumulated in the marrow, lungs and tumors of animals. These findings indicate that ADAS cells integrate in the animal body with transplanted tumor and can be identified by fluorescence bioimaging techniques in vivo and ex vivo.

  5. Synthesis of polymeric fluorescent brightener based on coumarin and its performances on paper as light stabilizer, fluorescent brightener and surface sizing agent

    Science.gov (United States)

    Zhang, Guanghua; Zheng, Hua; Guo, Mingyuan; Du, Lun; Liu, Guojun; Wang, Peng

    2016-03-01

    In this work, a novel polymeric fluorescent brightener based on coumarin (PFBC) was synthesized, using three-step synthetic route, from 7-amino-4-methylcoumarin, coumarin monomer (FBC), Acrylamide (AM) and methacrylatoethyl trimethyl ammonium chloride (DMC). The structure of PFBC was characterized by FT-IR, 1HNMR and GPC. PFBC was applied to paper fiber as light stabilizer, fluorescent brightener and surface sizing agent and its performances were evaluated by measuring the UV-vis, fluorescence, thermal stability, the cationic degree, surface strength and smoothness of paper, the brightness degree of paper and the PC value of paper. Results showed that PFBC had better solubility in water than that of FBC, by measuring the optical properties. Through the surface sizing experiment and UV aging experiment, PFBC not only enhanced the surface strength and smoothness of paper as a surface sizing agent, but also had better effect on anti-UV aging than that of FBC as light stabilizer and fluorescent brightener.

  6. An atlas of bright star spectra in the near infrared from Cassini-VIMS

    CERN Document Server

    Stewart, Paul N; Nicholson, Philip D; Sloan, G C; Hedman, Matthew M

    2015-01-01

    We present the Cassini Atlas Of Stellar Spectra (CAOSS), comprised of near-infrared low-resolution spectra of bright stars recovered from space-based observations by the Cassini spacecraft. The 65 stellar targets in the atlas are predominately M, K and S giants. However it also contains spectra of other bright nearby stars including carbon stars and main sequence stars from A to F. The spectra presented are free of all spectral contamination caused by the Earth's atmosphere, including the detrimental telluric molecular bands which put parts of the near-infrared spectrum out of reach of terrestrial observations. With a single instrument, a spectro-photometric dataset is recovered that spans the near-infrared from 0.8 to 5.1 microns with spectral resolution ranging from R=53.5 to R=325. Spectra have been calibrated into absolute flux units after careful characterisation of the instrumental spectral efficiency. Spectral energy distributions for most stars match closely with literature values. All final data prod...

  7. Compact collimators for high brightness blue LEDs using dielectric multilayers

    NARCIS (Netherlands)

    Cornelissen, H.J.; Ma, H.; Ho, C.; Li, M.; Mu, C.

    2011-01-01

    A novel method is presented to inject the light of millimeter-sized high-brightness blue LEDs into light guides of submillimeter thickness. Use is made of an interference filter that is designed to pass only those modes that will propagate in the light guide by total internal reflection. Other modes

  8. Soil Moisture Active/Passive (SMAP) Forward Brightness Temperature Simulator

    Science.gov (United States)

    Peng, Jinzheng; Peipmeier, Jeffrey; Kim, Edward

    2012-01-01

    The SMAP is one of four first-tier missions recommended by the US National Research Council's Committee on Earth Science and Applications from Space (Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond, Space Studies Board, National Academies Press, 2007) [1]. It is to measure the global soil moisture and freeze/thaw from space. One of the spaceborne instruments is an L-band radiometer with a shared single feedhorn and parabolic mesh reflector. While the radiometer measures the emission over a footprint of interest, unwanted emissions are also received by the antenna through the antenna sidelobes from the cosmic background and other error sources such as the Sun, the Moon and the galaxy. Their effects need to be considered accurately, and the analysis of the overall performance of the radiometer requires end-to-end performance simulation from Earth emission to antenna brightness temperature, such as the global simulation of L-band brightness temperature simulation over land and sea [2]. To assist with the SMAP radiometer level 1B algorithm development, the SMAP forward brightness temperature simulator is developed by adapting the Aquarius simulator [2] with necessary modifications. This poster presents the current status of the SMAP forward brightness simulator s development including incorporating the land microwave emission model and its input datasets, and a simplified atmospheric radiative transfer model. The latest simulation results are also presented to demonstrate the ability of supporting the SMAP L1B algorithm development.

  9. Matter wave interference pattern in the collision of bright solitons

    International Nuclear Information System (INIS)

    We investigate the dynamics of Bose-Einstein condensates in a quasi one-dimensional regime in a time-dependent trap and show analytically that it is possible to observe matter wave interference patterns in the intra-trap collision of two bright solitons by selectively tuning the trap frequency and scattering length.

  10. Minimum-phase distribution of cosmic source brightness

    International Nuclear Information System (INIS)

    Minimum-phase distributions of brightness (profiles) for cosmic radio sources 3C 144 (the wave lambda=21 cm), 3C 338 (lambda=3.5 m), and 3C 353 (labda=31.3 cm and 3.5 m) are obtained. A real possibility for the profile recovery from module fragments of its Fourier-image is shown

  11. The HI dominated Low Surface Brightness Galaxy KKR17

    CERN Document Server

    Lam, Man I; Yang, Ming; Zhou, Zhi-Min; Du, Wei; Zhu, Yi-Nan

    2014-01-01

    We present new narrow-band (H$\\alpha$ and [OIII]) imagings and optical spectrophotometry of HII regions for a gas-rich low surface brightness irregular galaxy, KKR 17. The central surface brightness of the galaxy is $\\mu_0(B)$ = 24.15 $\\pm$0.03 mag~sec$^{-2}$. The galaxy was detected by \\emph{Arecibo Legacy Fast ALFA survey} (ALFALFA), and its mass is dominated by neutral hydrogen (HI) gas. In contrast, both the stellar masses of the bright HII and diffuse stellar regions are small. In addition, the fit to the spectral energy distribution to each region shows the stellar populations of HII and diffuse regions are different. The bright HII region contains a large fraction of O-type stars, revealing the recent strong star formation, whereas the diffuse region is dominated by median age stars, which has a typical age of $\\sim$ 600 Myrs. Using the McGaugh's abundance model, we found that the average metallicity of KKR 17 is 12 + (O/H) = 8.0 $\\pm$ 0.1. The star formation rate of KKR 17 is 0.21$\\pm$0.04 M$_{\\odot}$...

  12. Bright infrared LEDs based on colloidal quantum-dots

    KAUST Repository

    Sun, Liangfeng

    2013-01-01

    Record-brightness infrared LEDs based on colloidal quantum-dots have been achieved through control of the spacing between adjacent quantum-dots. By tuning the size of quantum-dots, the emission wavelengths can be tuned between 900nm and 1650nm. © 2013 Materials Research Society.

  13. Bright-dark incoherently coupled photovoltaic soliton pair

    Institute of Scientific and Technical Information of China (English)

    Hou Chun-Feng; Pei Yan-Bo; Zhou Zhong-Xiang; Sun Xiu-Dong

    2005-01-01

    The coupling between two mutually incoherent optical beams that propagate collinearly in open-circuit photovoltaic photorefractive media is investigated. It is shown that an incoherently coupled bright-dark spatial soliton pair can be formed due to photovoltaic effect. The physical properties of such a soliton pair are also discussed.

  14. The star-bright hour : [poems] / Betti Alver

    Index Scriptorium Estoniae

    Alver, Betti, 1906-1989

    2003-01-01

    Autori lühitutvustus lk. 231. Sisu: The star-bright hour ; The debt ; Not a dream ; Fog-bound ; Corals in an Ancient river ; Frou-frou 1-3. Orig.: Tähetund ; Vilepuhuja ; Võlg ; "Mitte viirastus, meelepett..." ; Udus ; Korallid Emajões ; Froufrou 1-3

  15. Bright soliton trains of trapped Bose-Einstein condensates

    OpenAIRE

    Al Khawaja, U.; Stoof, H. T. C.; Hulet, R. G.; Strecker, K.E.; Patridge, G.B.

    2002-01-01

    We variationally determine the dynamics of bright soliton trains composed of harmonically trapped Bose-Einstein condensates with attractive interatomic interactions. In particular, we obtain the interaction potential between two solitons. We also discuss the formation of soliton trains due to the quantum mechanical phase fluctuations of a one-dimensional condensate.

  16. Bright X-ray galaxies in SDSS filaments

    OpenAIRE

    Tugay, A. V.

    2013-01-01

    Eighteen bright X-ray emitting galaxies were found in nearby filaments within SDSS region. Basic X-ray spectral parameters were estimated for these galaxies using power law model with photoelectric absorption. A close pair of X-ray galaxies was found.

  17. Optical variability of the medium-bright quasar sample

    International Nuclear Information System (INIS)

    A variability study of the 32-member Medium-Bright Quasar Sample is reported. It is found that the star US 1953 has undergone a noticeable variation in the course of 26 hr. Apparent variations in the extragalactic object US 3498 may be illusory, owing to its partially resolved appearance. No other evidence for variability was detected. 34 refs

  18. Thermionic sources for HI-brightness electron beams

    International Nuclear Information System (INIS)

    This paper surveys the capabilities and limitations of modern thermionic electron sources for producing high emission density (>10 A/cm2)-high brightness beams. The emphasis is on dispenser cathodes. The capabilities of existing commercial cathodes as well as the potential for future cathode improvements as demonstrated in various prototype structures are described

  19. Enhancing the brightness of high current electron guns

    International Nuclear Information System (INIS)

    Concepts such as the two-beam accelerator offer the possibility of translating pulsed power technology into a form useful to the design of high luminosity accelerators for high-energy physics applications. Realization of the promise of these concepts will require the design of electron guns which are optimized with respect to beam brightness at current levels of approximately 1 kA. Because high luminosity implies accelerator operation at high repetition rates, the high-current beam source must be designed so that the beam does not intercept the electrodes. In our investigations of electron gun configurations, we have found that the brightness of a given source is set by practical design choices such as peak voltage, cathode type, gun electrode geometry, and focusing field topology. To investigate the sensitivity of beam brightness to these factors in a manner suitable for modelling transient phenomena at the beam head, we have developed a Darwin approximation particle code, DPC. The main component in our experimental program is a readily modified electron gun that allows us to test many candidate cathode materials, types, and electrode geometries at field stresses up to 1 MW/cm. We have also developed several diagnostics suitable for measuring the brightness of intense, low-emittance beams

  20. The star-bright hour : [luuletused] / Betti Alver

    Index Scriptorium Estoniae

    Alver, Betti, 1906-1989

    2006-01-01

    Sisu: The star-bright hour ; Not a dream ; The Piper ; Corals in an ancent river. Luuletused pärinevad kogumikust "Tuulelaeval valgusest on aerud = Windship with Oars of Light. (Tallinn : Huma, 2001). Orig.: Tähetund ; Mitte viirastus, meelepett ; Vilepuhuja ; Korallid Emajões

  1. The "Brightness Rules" Alternative Conception for Light Bulb Circuits

    Science.gov (United States)

    Bryan, Joel A.; Stuessy, Carol

    2006-01-01

    An alternative conception for the observed differences in light bulb brightness was revealed during an unguided inquiry investigation in which prospective elementary teachers placed identical bulbs in series, parallel, and combination direct current circuits. Classroom observations, document analyses, and video and audio transcriptions led to the…

  2. Variations in the Fe mineralogy of bright Martian soil

    Science.gov (United States)

    Murchie, Scott; Mustard, John; Erard, Stephane; Geissler, Paul; Singer, Robert

    1993-01-01

    Bright regions on Mars are interpreted as 'soil' derived by chemical alteration of crustal rocks, whose main pigmentary component is ferric oxide or oxyhydroxide. The mineralogy and mineralogic variability of ferric iron are important evidence for the evolution of Martian soil: mineralogy of ferric phases is sensitive to chemical conditions in their genetic environments, and the spatial distributions of different ferric phases would record a history of both chemical environments and physical mixing. Reflectance spectroscopic studies provide several types of evidence that discriminate possible pigmentary phases, including the position of a crystal field absorption near 0.9 microns and position and strengths of absorptions in the UV-visible wavelength region. Recent telescopic spectra and laboratory measurements of Mars soil analogs suggest that spectral features of bright soil can be explained based on a single pigmentary phase, hematite (alpha-Fe2O3), occurring in both 'nanophase' and more crystalline forms. Here we report on a systematic investigation of Martian bright regions using ISM imaging spectrometer data, in which we examined spatial variations in the position and shape of the approximately 0.9 microns absorption. We found both local and regional heterogeneities that indicate differences in Fe mineralogy. These results demonstrate that bright soils do not represent a single lithology that has been homogenized by eolian mixing, and suggest that weathering of soils in different geologic settings has followed different physical and chemical pathways.

  3. Fluorescent Staining of Tea Pathogenic Fungi in Tea Leaves Using Fluorescein-labeled Lectin

    Science.gov (United States)

    Yamada, Kengo; Yoshida, Katsuyuki; Sonoda, Ryoichi

    Fluorochrome-labeled lectin, fluorescein conjugated wheat germ agglutinin (F-WGA) was applied to stain tea pathogenic fungi in tea leaf tissue. Infected leaves were fixed and decolorized with a mixture of ethanol and acetic acid, and cleared with 10% KOH for whole mount before staining with F-WGA. Hyphae of Pestalotiopsis longiseta, Pseudocercospora ocellata, Botrytis cinerea and Colletotrichum theae-sinensis fluoresced brightly in whole mount and sectioned samples of infected leaf tissue. In browned tissue, hyphae did not fluoresce frequently in whole mount sample. Autofluorescence of leaf tissue was strong in browned tissue of sections, it was removed by 10% KOH treatment before staining. Penetration hyphae of C. theae-sinensis in cell wall of trichome and hyphae in basal part of trichome did not fluoresced frequently. In whole mount samples of tea leaf infected with Exobasidium vexans and E. reticulatum, hymenia appeared on leaf surface fluoresced, but hyphae in leaf tissue did not fluoresce. In sectioned samples, hyphae fluoresced brightly when sections were treated with 10% KOH before staining.

  4. Several hemicyanine dyes as fluorescence chemosensors for cyanide anions

    Science.gov (United States)

    Liang, Muhan; Wang, Kangnan; Guan, Ruifang; Liu, Zhiqiang; Cao, Duxia; Wu, Qianqian; Shan, Yanyan; Xu, Yongxiao

    2016-05-01

    Four hemicyanine dyes as chemosensors for cyanide anions were synthesized easily. Their photophysical properties and recognition properties for cyanide anions were investigated. The results indicate that all the dyes can recognize cyanide anions with obvious color, absorption and fluorescence change. The recognition mechanism analysis basing on in situ 1H NMR and Job plot data indicates that to the compounds with hydroxyl group, the recognition mechanism is intramolecular hydrogen bonding interaction. However, to the compounds without hydroxyl group, cyanide anion is bonded to carbon-carbon double bond in conjugated bridge and induces N+ CH3 to neutral NCH3. Fluorescence of the compounds is almost quenched upon the addition of cyanide anions.

  5. Spectral Diversity and Regulation of Coral Fluorescence in a Mesophotic Reef Habitat in the Red Sea.

    Directory of Open Access Journals (Sweden)

    Gal Eyal

    Full Text Available The phenomenon of coral fluorescence in mesophotic reefs, although well described for shallow waters, remains largely unstudied. We found that representatives of many scleractinian species are brightly fluorescent at depths of 50-60 m at the Interuniversity Institute for Marine Sciences (IUI reef in Eilat, Israel. Some of these fluorescent species have distribution maxima at mesophotic depths (40-100 m. Several individuals from these depths displayed yellow or orange-red fluorescence, the latter being essentially absent in corals from the shallowest parts of this reef. We demonstrate experimentally that in some cases the production of fluorescent pigments is independent of the exposure to light; while in others, the fluorescence signature is altered or lost when the animals are kept in darkness. Furthermore, we show that green-to-red photoconversion of fluorescent pigments mediated by short-wavelength light can occur also at depths where ultraviolet wavelengths are absent from the underwater light field. Intraspecific colour polymorphisms regarding the colour of the tissue fluorescence, common among shallow water corals, were also observed for mesophotic species. Our results suggest that fluorescent pigments in mesophotic reefs fulfil a distinct biological function and offer promising application potential for coral-reef monitoring and biomedical imaging.

  6. Fluorescent Polymer Nanoparticles Based on Dyes: Seeking Brighter Tools for Bioimaging.

    Science.gov (United States)

    Reisch, Andreas; Klymchenko, Andrey S

    2016-04-01

    Speed, resolution and sensitivity of today's fluorescence bioimaging can be drastically improved by fluorescent nanoparticles (NPs) that are many-fold brighter than organic dyes and fluorescent proteins. While the field is currently dominated by inorganic NPs, notably quantum dots (QDs), fluorescent polymer NPs encapsulating large quantities of dyes (dye-loaded NPs) have emerged recently as an attractive alternative. These new nanomaterials, inspired from the fields of polymeric drug delivery vehicles and advanced fluorophores, can combine superior brightness with biodegradability and low toxicity. Here, we describe the strategies for synthesis of dye-loaded polymer NPs by emulsion polymerization and assembly of pre-formed polymers. Superior brightness requires strong dye loading without aggregation-caused quenching (ACQ). Only recently several strategies of dye design were proposed to overcome ACQ in polymer NPs: aggregation induced emission (AIE), dye modification with bulky side groups and use of bulky hydrophobic counterions. The resulting NPs now surpass the brightness of QDs by ≈10-fold for a comparable size, and have started reaching the level of the brightest conjugated polymer NPs. Other properties, notably photostability, color, blinking, as well as particle size and surface chemistry are also systematically analyzed. Finally, major and emerging applications of dye-loaded NPs for in vitro and in vivo imaging are reviewed. PMID:26901678

  7. Portable, battery-operated, fluorescence field microscope for the developing world

    Science.gov (United States)

    Miller, Andrew R.; Davis, Gregory; Pierce, Mark; Oden, Z. Maria; Richards-Kortum, Rebecca

    2010-02-01

    In many areas of the world, current methods for diagnosis of infectious diseases such as malaria and tuberculosis involve microscopic evaluation of a patient specimen. Advances in fluorescence microscopy can improve diagnostic sensitivity and reduce time and expertise necessary to interpret diagnostic results. However, modern research-grade microscopes are neither available nor appropriate for use in many settings in the developing world. To address this need, we designed, fabricated, and tested a portable, battery-powered, bright field and fluorescence inverted field microscope, optimized for infrastructural constraints of the developing world. We characterized an initial prototype constructed with rapidprototyping techniques, which utilized low-cost, over-the-counter components such as a battery-powered LED flashlight as the light source. The microscope exhibited suitable spatial resolution (0.8 μm) in fluorescence mode to resolve M. tuberculosis bacilli. In bright field mode, malaria parasites were resolvable at 1000x magnification. The initial prototype cost 480 USD and we estimate that the microscope can be manufactured for 230 USD. While future studies are planned to evaluate ease-of-use and reliability, our current system serves as a proof of concept that combined fluorescence and bright field microscopy is possible in a low-cost and portable system.

  8. Mapping the fluorescence performance of a photochromic-fluorescent system coupled with gold nanoparticles at the single-molecule-single-particle level.

    Science.gov (United States)

    Simoncelli, Sabrina; Roberti, M Julia; Araoz, Beatriz; Bossi, Mariano L; Aramendía, Pedro F

    2014-05-14

    Single-molecule (SM) fluorescence microscopy was used to investigate the photochromic fluorescent system spiropyran-merocyanine (SP ↔ MC) interacting with gold nanoparticles (AuNPs). We observe a significant increase in the brightness of the emissive MC form, in the duration of its ON time, and in the total number of emitted photons. The spatial distribution of SMs with improved photophysical performance was obtained with 40 nm precision relative to the nearest AuNP. We demonstrate that even photochromic systems with poor photochemical performance for SM can become suitable for long time monitoring and high performance microscopy by interaction with metallic NP. PMID:24766343

  9. On the model of type 1 supernova near brightness maximum

    International Nuclear Information System (INIS)

    Some photometric and spectrophotometric data about supernovae of 1 type CH-1 are analyzed. Colour /Tsub(c)/ and spectrophotmetric /T/ temperatures of SN1972-e compared. It has been concluded that at the maximum brightness tsub(m) and before the maximum Tsub(c) approximately TTsub(c) < T after the maximum brightness. A considerable deviation of Tsub(c) from T is connected with the significant role of metal lines in the attenuation of the short-wavelength region spectrum CH-1, which becomes essential when T < 10000 deg K. Behaviour of the radius of the photosphere Rp at CH-1 is investigated on the basis of the accepted dependence of T on time. It is shown that at the maximum brightness Rp, increases linearly at the rate of about 5000 km/sec, and reaches its highest value approximately in 30-35sup(d) after the maximum brightness tsub(m) and then rather quickly decreases. The rate of the expansion of the photosphere is twice lower than the mean expansion velocity of the shell CH-1. The initial moments of separation of these CH are -25sup(d) and -16sup(d) respectively (with respect to the maximum V) have been found using an extrapolation of the Rp(t) dependence for SN 1972-e and SN 1970-j. The role of the temperature dependence of non-transparency on the behavior of the photosphere Ch-1 is discussed. Bolomeic luminosity of CH-1 at the maximum brightness is investigated. Arguments supporting the conclusion that the bolometric maximum of CH-1 comes formerly to a visual one, are given

  10. Luminescent carbon quantum dots with high quantum yield as a single white converter for white light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Feng, X. T.; Zhang, Y.; Liu, X. G., E-mail: liuxuguang@tyut.edu.cn [Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Taiyuan 030024 (China); College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Zhang, F.; Wang, Y. L.; Yang, Y. Z., E-mail: yyztyut@126.com [Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Taiyuan 030024 (China); Research Center on Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China)

    2015-11-23

    Carbon quantum dots (CQDs) with high quantum yield (51.4%) were synthesized by a one-step hydrothermal method using thiosalicylic acid and ethylenediamine as precursor. The CQDs have the average diameter of 2.3 nm and possess excitation-independent emission wavelength in the range from 320 to 440 nm excitation. Under an ultraviolet (UV) excitation, the CQDs aqueous solutions emit bright blue fluorescence directly and exhibit broad emission with a high spectral component ratio of 67.4% (blue to red intensity to total intensity). We applied the CQDs as a single white-light converter for white light emitting diodes (WLEDs) using a UV-LED chip as the excitation light source. The resulted WLED shows superior performance with corresponding color temperature of 5227 K and the color coordinates of (0.34, 0.38) belonging to the white gamut.

  11. Luminescent carbon quantum dots with high quantum yield as a single white converter for white light emitting diodes

    International Nuclear Information System (INIS)

    Carbon quantum dots (CQDs) with high quantum yield (51.4%) were synthesized by a one-step hydrothermal method using thiosalicylic acid and ethylenediamine as precursor. The CQDs have the average diameter of 2.3 nm and possess excitation-independent emission wavelength in the range from 320 to 440 nm excitation. Under an ultraviolet (UV) excitation, the CQDs aqueous solutions emit bright blue fluorescence directly and exhibit broad emission with a high spectral component ratio of 67.4% (blue to red intensity to total intensity). We applied the CQDs as a single white-light converter for white light emitting diodes (WLEDs) using a UV-LED chip as the excitation light source. The resulted WLED shows superior performance with corresponding color temperature of 5227 K and the color coordinates of (0.34, 0.38) belonging to the white gamut

  12. A fluorescent laser-diffuser arrangement for uniform backlighting

    Science.gov (United States)

    Jain, Saransh; Somasundaram, S.; Anand, T. N. C.

    2016-02-01

    Laser-light diffusers are used in conjunction with pulsed lasers to generate bright, spatially uniform background illumination for imaging and particle sizing applications. The present paper describes a cost effective way of fabricating a fluorescent laser-light diffuser. The procedure to obtain a uniform background using laser illumination is explained. To characterize the diffuser, images are acquired using a CCD camera with the illumination provided using the diffuser and the variations of pixel intensity values along the centerline of the images are plotted. It is observed that the standard deviation of pixel intensity values is fairly small. Hence, these diffusers are suitable for experiments that need a uniform background.

  13. A study on materials of steels by high brightness X-ray

    CERN Document Server

    Tsuzaki, K; Umezawa, O; Hara, T; Takahashi, T; Omura, T; Hayakawa, M; Yamauchi, Y

    2001-01-01

    As the survey study on materials analysis of steels using high brightness X-ray, under aiming to clarify direct experimental facts on deformations, failure phenomena, and metal textures forming at interior portions of bulk materials, feasibility on materials research and development using SPring-8 was surveyed. Its concrete items were summarized to fields shown as follows: 1) acquirement of foundation on synchrotron X-ray, 2) visualization of cracks and artificial cracks in metal bulk samples by using refraction imaging (point light source topography), 3) visualization of the second phase in the metal bulk samples by using refraction imaging, and 4) speciation of carbon elements in steel cords by Moessbauer spectroscopy. Together with clarifying problems more and more by the survey and some experiments, subjects and understandings vacantly considered at standpoints of materials researchers could be arranged and defined. (G.K.)

  14. Fluorescent image tracking velocimeter

    Science.gov (United States)

    Shaffer, Franklin D.

    1994-01-01

    A multiple-exposure fluorescent image tracking velocimeter (FITV) detects and measures the motion (trajectory, direction and velocity) of small particles close to light scattering surfaces. The small particles may follow the motion of a carrier medium such as a liquid, gas or multi-phase mixture, allowing the motion of the carrier medium to be observed, measured and recorded. The main components of the FITV include: (1) fluorescent particles; (2) a pulsed fluorescent excitation laser source; (3) an imaging camera; and (4) an image analyzer. FITV uses fluorescing particles excited by visible laser light to enhance particle image detectability near light scattering surfaces. The excitation laser light is filtered out before reaching the imaging camera allowing the fluoresced wavelengths emitted by the particles to be detected and recorded by the camera. FITV employs multiple exposures of a single camera image by pulsing the excitation laser light for producing a series of images of each particle along its trajectory. The time-lapsed image may be used to determine trajectory and velocity and the exposures may be coded to derive directional information.

  15. Self-assembly of diphenylalanine peptides into microtubes with "turn on" fluorescence using an aggregation-induced emission molecule.

    Science.gov (United States)

    Na, Na; Mu, Xiaoyan; Liu, Qiuling; Wen, Jiying; Wang, Fangfang; Ouyang, Jin

    2013-10-01

    The self-assembly of diphenylalanine peptides (l-Phe-l-Phe) into microtubes with "turn on" bright yellow green fluorescence was described, which was achieved using an aggregation-induced emission (AIE) molecule of 9,10-bis[4-(3-sulfonatopropoxyl)-styryl] anthracene (BSPSA) sodium. PMID:24045462

  16. LARGER PLANET RADII INFERRED FROM STELLAR ''FLICKER'' BRIGHTNESS VARIATIONS OF BRIGHT PLANET-HOST STARS

    International Nuclear Information System (INIS)

    Most extrasolar planets have been detected by their influence on their parent star, typically either gravitationally (the Doppler method) or by the small dip in brightness as the planet blocks a portion of the star (the transit method). Therefore, the accuracy with which we know the masses and radii of extrasolar planets depends directly on how well we know those of the stars, the latter usually determined from the measured stellar surface gravity, log g. Recent work has demonstrated that the short-timescale brightness variations (flicker) of stars can be used to measure log g to a high accuracy of ∼0.1-0.2 dex. Here, we use flicker measurements of 289 bright (Kepmag < 13) candidate planet-hosting stars with T eff = 4500-6650 K to re-assess the stellar parameters and determine the resulting impact on derived planet properties. This re-assessment reveals that for the brightest planet-host stars, Malmquist bias contaminates the stellar sample with evolved stars: nearly 50% of the bright planet-host stars are subgiants. As a result, the stellar radii, and hence the radii of the planets orbiting these stars, are on average 20%-30% larger than previous measurements had suggested

  17. LARGER PLANET RADII INFERRED FROM STELLAR ''FLICKER'' BRIGHTNESS VARIATIONS OF BRIGHT PLANET-HOST STARS

    Energy Technology Data Exchange (ETDEWEB)

    Bastien, Fabienne A.; Stassun, Keivan G.; Pepper, Joshua [Physics and Astronomy Department, Vanderbilt University, 1807 Station B, Nashville, TN 37235 (United States)

    2014-06-10

    Most extrasolar planets have been detected by their influence on their parent star, typically either gravitationally (the Doppler method) or by the small dip in brightness as the planet blocks a portion of the star (the transit method). Therefore, the accuracy with which we know the masses and radii of extrasolar planets depends directly on how well we know those of the stars, the latter usually determined from the measured stellar surface gravity, log g. Recent work has demonstrated that the short-timescale brightness variations ({sup f}licker{sup )} of stars can be used to measure log g to a high accuracy of ∼0.1-0.2 dex. Here, we use flicker measurements of 289 bright (Kepmag < 13) candidate planet-hosting stars with T {sub eff} = 4500-6650 K to re-assess the stellar parameters and determine the resulting impact on derived planet properties. This re-assessment reveals that for the brightest planet-host stars, Malmquist bias contaminates the stellar sample with evolved stars: nearly 50% of the bright planet-host stars are subgiants. As a result, the stellar radii, and hence the radii of the planets orbiting these stars, are on average 20%-30% larger than previous measurements had suggested.

  18. Luminescence of carbon monoxide hemocyanins.

    OpenAIRE

    Kuiper, H.A.; Agrò, A F; Antonini, E; Brunori, M

    1980-01-01

    The effect of carbon monoxide on the luminescence properties of Helix pomatia alpha-hemocyanin and Panulirus interruptus hemocyanin has been studied. These proteins, when saturated with carbon monoxide, show, besides the intrinsic fluorescence arising from the aromatic amino acid residues, emission in the visible region with a maximum between 540 and 560 nm. Results of carbon monoxide titration experiments and data from absorption and excitation-emission spectra provide convincing evidence th...

  19. Fluorescence labeled microbubbles for multimodal imaging.

    Science.gov (United States)

    Barrefelt, Åsa; Zhao, Ying; Larsson, Malin K; Egri, Gabriella; Kuiper, Raoul V; Hamm, Jörg; Saghafian, Maryam; Caidahl, Kenneth; Brismar, Torkel B; Aspelin, Peter; Heuchel, Rainer; Muhammed, Mamoun; Dähne, Lars; Hassan, Moustapha

    2015-08-28

    Air-filled polyvinyl alcohol microbubbles (PVA-MBs) were recently introduced as a contrast agent for ultrasound imaging. In the present study, we explore the possibility of extending their application in multimodal imaging by labeling them with a near infrared (NIR) fluorophore, VivoTag-680. PVA-MBs were injected intravenously into FVB/N female mice and their dynamic biodistribution over 24 h was determined by 3D-fluorescence imaging co-registered with 3D-μCT imaging, to verify the anatomic location. To further confirm the biodistribution results from in vivo imaging, organs were removed and examined histologically using bright field and fluorescence microscopy. Fluorescence imaging detected PVA-MB accumulation in the lungs within the first 30 min post-injection. Redistribution to a low extent was observed in liver and kidneys at 4 h, and to a high extent mainly in the liver and spleen at 24 h. Histology confirmed PVA-MB localization in lung capillaries and macrophages. In the liver, they were associated with Kupffer cells; in the spleen, they were located mostly within the marginal-zone. Occasional MBs were observed in the kidney glomeruli and interstitium. The potential application of PVA-MBs as a contrast agent was also studied using ultrasound (US) imaging in subcutaneous and orthotopic pancreatic cancer mouse models, to visualize blood flow within the tumor mass. In conclusion, this study showed that PVA-MBs are useful as a contrast agent for multimodal imaging. PMID:26187672

  20. 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

    The use of the NIR spectral region (650-900 nm) is advantageous due to the inherently lower background interference and the high molar absorptivities of NIR chromophores. Near-Infrared (NIR) dyes are increasingly used in the biological and medical field. The binding characteristics of NIR dyes to biomolecules are possibly controlled by several factors, including hydrophobicity, size and charge just to mention a few parameters. Binding characteristics of symmetric carbocyanines and found that the hydrophobic nature of the NIR dye is only partially responsible for the binding strength. Upon binding to biomolecules significant fluorescence enhancement can be observed for symmetrical carbocyanines. This fluorescence amplification facilitates the detection of the NIR dye and enhances its utility as NIR reporter. This manuscript discusses some probe and marker applications of such NIR fluorescent dyes. One application discussed here is the use of NIR dyes as markers. For labeling applications the fluorescence intensity of the NIR fluorescent label can significantly be increased by enclosing several dye molecules in nanoparticles. To decrease self quenching dyes that have relatively large Stokes' shift needs to be used. This is achieved by substituting meso position halogens with amino moiety. This substitution can also serve as a linker to covalently attach the dye molecule to the nanoparticle backbone. We report here on the preparation of NIR fluorescent silica nanoparticles. Silica nanoparticles that are modified with aminoreactive moieties can be used as bright fluorescent labels in bioanalytical applications. A new bioanalytical technique to detect and monitor the catalytic activity of the sulfur assimilating enzyme using NIR dyes is reported as well. In this spectroscopic bioanalytical assay a family of Fischer based n-butyl sulfonate substituted dyes that exhibit distinct variation in absorbance and fluorescence properties and strong binding to serum albumin as its