Artículos de revistas: "Fluorescent concentrator"

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A . Hussein, Ahmed y Adnan F. Hassan. "Performance Enhancement of Luminescent Solar Concentrator by using Mixing Fluorescent Colors and Nanoparticles". Journal of Kufa-Physics 14, n.º 01 (12 de agosto de 2022): 17–25. http://dx.doi.org/10.31257/2018/jkp/2022/140106.

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Liquid zinc acetate nanoparticles were added to a fluorescent organic dye (fluorescein sodium) to prepare three concentrations (2 × 10-5, 7×10-5, 1×10-4) moI/L, and the absorbance of the dye was measured before and after adding Liquid nanomaterial by using two devices (SCINCO Mega-2100 UV/visible Spectrophotometer.) as well as measuring the flux of the dye before and after adding zinc acetate nanoparticles using the (Spectrofluorometer F96 PRO). The Stoke displacement (Δη), the radiative age (τfm), the fluorescence lifetime (τf), and the quantitative efficiency (Qfm) were calculated. Absorption and fluorescence curves were drawn using the Excel program. The MATLAB program was also used to measure the area under the absorption and fluorescence spectra curves. It was found that the fluorescence intensity of fluorescein sodium dye has increased compared to the intensity of fluorescence before adding the nanomaterial and thus increasing the quantitative efficiency, which in turn helps in improving the performance of the photovoltaic concentrator, resulting in an improvement in the efficiency of the solar cell.

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Sidahmed, Abrar y Adrian Kitai. "Tandem Ce:YAG fluorescent solar concentrator". Solar Energy Materials and Solar Cells 145 (febrero de 2016): 217–25. http://dx.doi.org/10.1016/j.solmat.2015.10.027.

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Goldschmidt, Jan Christoph, Marius Peters, Armin Bösch, Henning Helmers, Frank Dimroth, Stefan W. Glunz y Gerhard Willeke. "Increasing the efficiency of fluorescent concentrator systems". Solar Energy Materials and Solar Cells 93, n.º 2 (febrero de 2009): 176–82. http://dx.doi.org/10.1016/j.solmat.2008.09.048.

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4

Swift, Paul D. y Geoff B. Smith. "Color considerations in fluorescent solar concentrator stacks". Applied Optics 42, n.º 25 (1 de septiembre de 2003): 5112. http://dx.doi.org/10.1364/ao.42.005112.

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Minei, Pierpaolo, Elisabetta Fanizza, Antonio M. Rodríguez, Ana B. Muñoz-García, Paola Cimino, Michele Pavone y Andrea Pucci. "Cost-effective solar concentrators based on red fluorescent Zn(ii)–salicylaldiminato complex". RSC Advances 6, n.º 21 (2016): 17474–82. http://dx.doi.org/10.1039/c5ra23049g.

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6

Wang, Zhaoming, Li Zhang, Jingzhou Li, Guodan Wei, Yuhan Dong y H. Y. Fu. "Fluorescent concentrator based MISO-NOMA for visible light communications". Optics Letters 47, n.º 4 (9 de febrero de 2022): 902. http://dx.doi.org/10.1364/ol.449120.

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7

Mansour, A. F., M. H. El Gazaly, M. Gaber y R. M. Ahmed. "Characterization of Polymer Films for Fluorescent Solar-concentrator Applications". International Journal of Polymeric Materials 54, n.º 3 (enero de 2005): 237–46. http://dx.doi.org/10.1080/00914030390246793.

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Slooff, Lenneke H., Nicolaas J. Bakker, Paul M. Sommeling, Andreas Büchtemann, Armin Wedel y Wilfried G. J. H. M. van Sark. "Long-term optical stability of fluorescent solar concentrator plates". physica status solidi (a) 211, n.º 5 (10 de febrero de 2014): 1150–54. http://dx.doi.org/10.1002/pssa.201330447.

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9

Wang, Chen, H. Abdul-Rahman y S. P. Rao. "Development and Testing of a Fluorescent Fiber Solar Concentrator for Remote Daylighting". Journal of Energy Engineering 136, n.º 3 (septiembre de 2010): 76–86. http://dx.doi.org/10.1061/(asce)ey.1943-7897.0000025.

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10

Mulyawan, Rahmat, Hyunchae Chun, Ariel Gomez, Sujan Rajbhandari, Grahame Faulkner, Pavlos P. Manousiadis, Dimali A. Vithanage et al. "MIMO Visible Light Communications Using a Wide Field-of-View Fluorescent Concentrator". IEEE Photonics Technology Letters 29, n.º 3 (1 de febrero de 2017): 306–9. http://dx.doi.org/10.1109/lpt.2016.2647717.

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Martínez Díez, Ana Luisa, Johannes Gutmann, Janina Posdziech, Tim Rist, David Gómez Plaza y Jan Christoph Goldschmidt. "Optimized scalable stack of fluorescent solar concentrator systems with bifacial silicon solar cells". Journal of Applied Physics 116, n.º 15 (21 de octubre de 2014): 154507. http://dx.doi.org/10.1063/1.4897926.

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Hase, Shunnosuke, Yoshiki Iso y Tetsuhiko Isobe. "Bandgap-tuned fluorescent CuGaS₂/ZnS core/shell quantum dots for photovoltaic applications". Journal of Materials Chemistry C 10, n.º 9 (2022): 3523–30. http://dx.doi.org/10.1039/d1tc05358b.

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Oh, Seoyeon, Yejin Lee, Minseok Yu, Seonghyeon Cho, Sana Javed y Hyunchae Chun. "Smart License Plate in Combination with Fluorescent Concentrator for Vehicular Visible Light Communication System". Sensors 22, n.º 7 (24 de marzo de 2022): 2485. http://dx.doi.org/10.3390/s22072485.

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Vehicle-to-vehicle communication based on visible light communication has gained much attention. This work proposes a smart license plate receiver incorporated with a fluorescent concentrator, enabling a fast vehicle-to-vehicle communication with a large field of view and high optical gain. Communication performance is experimentally analyzed using off-the-shelf light-emitting diode-based headlamps for low-latency direct line of sight channel. Additionally, a blue laser diode-based beam-steering and tracking system, through image processing of taillights with a steerable mirror, is investigated. Data rates of 54 Mbps from the headlamps and 532 Mbps from the beam-steering channel with ±25° are demonstrated. In addition, real-time video streaming through the beam-steering channel is presented.

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Cho, Seonghyeon y Hyunchae Chun. "Reflection based coupling efficiency enhancement in a fluorescent planar concentrator for an optical wireless receiver". Optics Express 29, n.º 18 (23 de agosto de 2021): 28901. http://dx.doi.org/10.1364/oe.434880.

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15

Parola, Itxaso, M. Asuncion Illarramendi, Florian Jakobs, Jana Kielhorn, Daniel Zaremba, Hans-Hermann Johannes y Joseba Zubia. "Characterization of Double-Doped Polymer Optical Fibers as Luminescent Solar Concentrators". Polymers 11, n.º 7 (15 de julio de 2019): 1187. http://dx.doi.org/10.3390/polym11071187.

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This work reports on a diameter dependence analysis of the performance as luminescent solar concentrators of three self-fabricated polymer optical fibers (POFs) doped with a hybrid combination of dopants. The works carried out include the design and self-fabrication of the different diameter fibers; an experimental analysis of the output power, of the output irradiance and of the fluorescent fiber solar concentrator efficiency; a comparison of the experimental results with a theoretical model; a study of the performance of all the fibers under different simulated lighting conditions; and a calculation of the active fiber length of each of the samples, all of them as a function of the fiber core diameter. To the best of our knowledge, this paper reports the first analysis of the influence of the POF diameter for luminescent solar concentration applications. The results obtained offer a general perspective on the optimal design of solar energy concentrating systems based on doped POFs and pave the way for the implementation of cost-effective solar energy concentrating devices.

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Wang, Chen, H. Abdul-Rahman y S. P. Rao. "Daylighting can be fluorescent: Development of a fiber solar concentrator and test for its indoor illumination". Energy and Buildings 42, n.º 5 (mayo de 2010): 717–27. http://dx.doi.org/10.1016/j.enbuild.2009.11.011.

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Núñez, R., I. Antón y G. Sala. "Proof-of-concept of a building-integrated hybrid concentrator photovoltaics-lighting system". Lighting Research & Technology 50, n.º 7 (11 de julio de 2017): 1082–90. http://dx.doi.org/10.1177/1477153517719119.

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A hybrid concentrator photovoltaics (CPV) module that combines the production of electricity and transports sunlight is proposed as a means to reduce the energy needs of buildings by two complementary solar energy approaches. Both concepts share the need for a solar tracker and an infrastructure to concentrate the sunlight which allows a reduction in costs of the proposed system. The CPV part is a well-known technology to produce electricity that serves as a host for the light subpart that transports sunlight through optical fibres. Measurements of a proof-of-concept show that in nominal conditions the lighting subpart is more efficient in the task of transporting sunlight than converting sunlight to electricity and then to light again. The efficiency threshold is a direct function of the fibre material and distance transported and the generated light is very similar to the solar light in terms of spectral content. Based on PMMA optical fibres and conventional CPV technology, the hybrid module converts 28.7% of the sunlight into electricity. Regarding the light transported by the optical fibres they slightly shift sunlight to bluish white but the quality of light is still comparable to a typical fluorescent lamp used in offices.

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Kapil, Gaurav, Yuhei Ogomi, Shyam S. Pandey, Tingli Ma y Shuzi Hayase. "Indoor Light Performance of Coil Type Cylindrical Dye Sensitized Solar Cells". Journal of Nanoscience and Nanotechnology 16, n.º 4 (1 de abril de 2016): 3183–87. http://dx.doi.org/10.1166/jnn.2016.12324.

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A very good performance under low/diffused light intensities is one of the application areas in which dye-sensitized solar cells (DSSCs) can be utilized effectively compared to their inorganic silicon solar cell counterparts. In this article, we have investigated the 1 SUN and low intensity fluorescent light performance of Titanium (Ti)-coil based cylindrical DSSC (C-DSSC) using ruthenium based N719 dye and organic dyes such as D205 and Y123. Electrochemical impedance spectroscopic results were analyzed for variable solar cell performances. Reflecting mirror with parabolic geometry as concentrator was also utilized to tap diffused light for indoor applications. Fluorescent light at relatively lower illumination intensities (0.2 mW/cm2 to 0.5 mW/cm2) were used for the investigation of TCO-less C-DSSC performance with and without reflector geometry. Furthermore, the DSSC performances were analyzed and compared with the commercially available amorphous silicon based solar cell for indoor applications.

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Xu, Bing, Jianying Wang, Chen Cai, Wei Xin, Lai Wei, Qinsi Yang, Bo Peng, Yuandu Hu, Jinhua Li y Xianbao Wang. "Construction of Laminated Luminescent Solar Concentrator “Smart” Window Based on Thermoresponsive Polymer and Carbon Quantum Dots". Crystals 12, n.º 11 (11 de noviembre de 2022): 1612. http://dx.doi.org/10.3390/cryst12111612.

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Conventional luminescent solar concentrators (LSCs) lack the ability of dynamic modulation, energy saving, and privacy protection. In this work, a thermoresponsive laminated LSC was created and further used as a “smart” window (SW). The laminated LSC “smart” window (LSC-SW) was prepared by introducing carbon quantum dots (CQDs) into the sandwiched LSCs filled with aqueous thermosensitive polymer (PNIPAm) solution. To realize better compatibility, two types of fluorescent materials, hydrophilic CQDs (blue and green emitting CQDs), had been synthesized. The LSC-SW showed a good dynamic response to the ambient temperature and solar irradiation, which can be switched between transparent (<32 °C) and opaque states (>32 °C). Besides, the optimal LSC-SW had high transmittance (>80%) at the transparent state and low transmittance (<10%) at the opaque state. More importantly, the opaque state enabled the LSC-SW with higher external optical efficiency (ηopt of 7.49%), energy saving.

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Lieberherr, Gian, Kevin Auderset, Bertrand Calpini, Bernard Clot, Benoît Crouzy, Martin Gysel-Beer, Thomas Konzelmann et al. "Assessment of real-time bioaerosol particle counters using reference chamber experiments". Atmospheric Measurement Techniques 14, n.º 12 (8 de diciembre de 2021): 7693–706. http://dx.doi.org/10.5194/amt-14-7693-2021.

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Abstract. This study presents the first reference calibrations of three commercially available bioaerosol detectors. The Droplet Measurement Technologies WIBS-NEO (new version of the wideband integrated bioaerosol spectrometer), Plair Rapid-E, and Swisens Poleno were compared with a primary standard for particle number concentrations at the Federal Institute for Metrology (METAS). Polystyrene (PSL) spheres were used to assess absolute particle counts for diameters from 0.5 to 10 µm. For the three devices, counting efficiency was found to be strongly dependent on particle size. The results confirm the expected detection range for which the instruments were designed. While the WIBS-NEO achieves its highest efficiency with smaller particles, e.g. 90 % for 0.9 µm diameter, the Plair Rapid-E performs best for larger particles, with an efficiency of 58 % for particles with a diameter of 10 µm. The Swisens Poleno is also designed for larger particles but operates well from 2 µm. However, the exact counting efficiency of the Poleno could not be evaluated as the cut-off diameter range of the integrated concentrator unit was not completely covered. In further experiments, three different types of fluorescent particles were tested to investigate the fluorescent detection capabilities of the Plair Rapid-E and the Swisens Poleno. Both instruments showed good agreement with the reference data. While the challenge to produce known concentrations of larger particles above 10 µm or even fresh pollen particles remains, the approach presented in this paper provides a potential standardised validation method that can be used to assess counting efficiency and fluorescence measurements of automatic bioaerosol monitoring devices.

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Turek-Etienne, Tammy C., Eliza C. Small, Sharon C. Soh, Tianpei A. Xin, Priti V. Gaitonde, Ellen B. Barrabee, Richard F. Hart y Robert W. Bryant. "Evaluation of Fluorescent Compound Interference in 4 Fluorescence Polarization Assays: 2 Kinases, 1 Protease, and 1 Phosphatase". Journal of Biomolecular Screening 8, n.º 2 (abril de 2003): 176–84. http://dx.doi.org/10.1177/1087057103252304.

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With the increasing use of fluorescence-based assays in high-throughput screening (HTS), the possibility of interference by fluorescent compounds needs to be considered. To investigate compound interference, a well-defined sample set of biologically active compounds, LOPAC™, was evaluated using 4 fluorescein-based fluorescence polarization (FP) assays. Two kinase assays, a protease assay, and a phosphatase assay were studied. Fluorescent compound interference and light scattering were observed in both mixture- and single-compound testing under certain circumstances. In the kinase assays, which used low levels (1-3 nM) of fluorophore, an increase in total fluorescence, an abnormal decrease in mP readings, and negative inhibition values were attributed to compound fluorescence. Light scattering was observed by an increase in total fluorescence and minimal reduction in mP, leading to false positives. The protease and phosphatase assays, which used a higher concentration of fluorophore (20-1200 nM) than the kinase assays, showed minimal interference from fluorescent compounds, demonstrating that an increase in the concentration of the fluorophore minimized potential fluorescent compound interference. The data also suggests that mixtures containing fluorescent compounds can result in either false negatives that can mask a potential “hit” or false positives, depending on the assay format. Cy™ dyes (e.g., Cy3B™ and Cy5™) excite and emit further into the red region than fluorescein and, when used in place of fluorescein in kinase 1, eliminate fluorescence interference and light scattering by LOPAC™ compounds. This work demonstrates that fluorescent compound and light scattering interferences can be overcome by increasing the fluorophore concentration in an assay or by using longer wavelength dyes. ( Journal of Biomolecular Screening 2003:176-184)

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Liu, Hao, Minglei Lu, Fukui Pan, Xin Ning y Jinfa Ming. "Influence of fluorescent dyes for dyeing of regenerated cellulose fabric". Textile Research Journal 90, n.º 11-12 (5 de diciembre de 2019): 1385–95. http://dx.doi.org/10.1177/0040517519892915.

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This study attempted to dye regenerated cellulose fiber fabric with fluorescent dyes in different conditions (dyeing time, temperature, pH, concentration, etc.) and investigated their effects on color strength, fluorescence intensity, and other properties of dyed fabrics. The exhaust dyeing method was applied in this experiment for cellulose based knitted fabrics. The physical properties of dyed knitted fabrics before and after treatment with fluorescent dyes were determined and evaluated. After fluorescent staining, the results showed that a large number of granular fluorescent particles were coated on the fiber surface. Higher K/ S values were obtained under conditions of a dyeing temperature of 80℃, dyeing time of 30 min, and NaCl concentration of 1 wt% than other conditions. Moreover, the fluorescence intensity of the dyed fabric was also highest at 80℃. The color strength and bursting strength of dyed knitted fabrics were increased with the increase of the concentration of fluorescein sodium. Thus, cellulose based knitted fabric dyed with fluorescent dyes exhibited excellent fluorescent properties and could be used in fluorescent clothing.

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Angelides, K. J., K. E. Smith y M. Takeda. "Assembly and exchange of intermediate filament proteins of neurons: neurofilaments are dynamic structures." Journal of Cell Biology 108, n.º 4 (1 de abril de 1989): 1495–506. http://dx.doi.org/10.1083/jcb.108.4.1495.

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We have explored the dynamics of intermediate filament assembly and subunit exchange using fluorescently labeled neurofilament proteins and a fluorescence resonance energy transfer assay. Neurofilaments (NFs) are assembled from three highly phosphorylated proteins with molecular masses of 180 (NF-H), 130 (NF-M), and 66 kD (NF-L) of which NF-L forms the structural core. The core component, NF-L, was stoichiometrically labeled at cysteine 321 with fluorescein, coumarin, or biotin-maleimide to produce assembly-competent fluorescent or biotinylated derivatives, respectively. Using coumarin-labeled NF-L as fluorescence donor and fluorescein-labeled NF-L as the fluorescence acceptor, assembly of NF filaments was induced by rapidly raising the NaCl concentration to 170 mM, and the kinetics was followed by the decrease in the donor fluorescence. Assembly of NF-L subunits into filaments does not require nucleotide binding or hydrolysis but is strongly dependent on ionic strength, pH, and temperature. The critical concentration of NF-L, that concentration that remains unassembled at equilibrium with fully formed filaments, is 38 micrograms/ml or 0.6 microM. Under physiological salt conditions NF-L filaments also undergo extensive subunit exchange. Kinetic analysis and evaluation of several possible mechanisms indicate that subunit exchange is preceded by dissociation of subunits from the filament and generation of a kinetically active pool of soluble subunits. Given the concentration of NF-L found in nerve cells and the possibility of regulating this pool, these results provide the first information that intermediate filaments are dynamic structures and that NF-L within the NF complex is in dynamic equilibrium with a small but kinetically active pool of unassembled NF-L units.

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Yamamoto, Johtaro y Akira Sasaki. "Fluorescence Correlation Spectroscopy Measurement Based on Fiber Optics for Biological Materials". Applied Sciences 11, n.º 15 (22 de julio de 2021): 6744. http://dx.doi.org/10.3390/app11156744.

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A robust fluorescence correlation spectroscopy system called fiber-optic based fluorescence correlation spectroscopy (FB-FCS) was developed; this system enables the measurement of diffusion dynamics and concentration of fluorescent molecules based on the principle of fluorescence correlation spectroscopy without any mechanical adjustment of the experimental setup. The system consisted of fiber optics and a water-immersion objective lens. The hydrodynamic diameters and concentrations of organic fluorescent dyes and fluorescently labeled proteins were successfully measured. Because of the fiber-optic-based setup, the FB-FCS system is compact and inexpensive. We expect FB-FCS to be suitable for use in laboratories, medical diagnosis, and environmental measurements.

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More, Lim, Kang, Yun, Yee y Chang. "Asymmetric and Reduced Xanthene Fluorophores: Synthesis, Photochemical Properties, and Application to Activatable Fluorescent Probes for Detection of Nitroreductase". Molecules 24, n.º 17 (3 de septiembre de 2019): 3206. http://dx.doi.org/10.3390/molecules24173206.

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Xanthene fluorophores, including fluorescein, rhodol, and rhodamines, are representative classes of fluorescent probes that have been applied in the detection and visualization of biomolecules. “Turn on” activatable fluorescent probes, that can be turned on in response to enzymatic reactions, have been developed and prepared to reduce the high background signal of “always-on” fluorescent probes. However, the development of activity-based fluorescent probes for biological applications, using simple xanthene dyes, is hampered by their inefficient synthetic methods and the difficulty of chemical modifications. We have, thus, developed a highly efficient, versatile synthetic route to developing chemically more stable reduced xanthene fluorophores, based on fluorescein, rhodol, and rhodamine via continuous Pd-catalyzed cross-coupling. Their fluorescent nature was evaluated by monitoring fluorescence with variation in the concentration, pH, and solvent. As an application to activatable fluorescent probe, nitroreductase (NTR)-responsive fluorescent probes were also developed using the reduced xanthene fluorophores, and their fluorogenic properties were evaluated.

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Chin, Suk Fun, Aressa Azman, Suh Cem Pang y Sing Muk Ng. "Fluorescein-Labeled Starch Maleate Nanoparticles as Sensitive Fluorescent Sensing Probes for Metal Ions". Journal of Nanomaterials 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/108359.

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Fluorescein 5(6)-isothiocyanate starch maleate (FISM) nanoparticles were prepared by covalently attached fluorescein 5(6)-isothiocyanate (FITC) with starch maleate. FISM nanoparticles with a mean particle size of 87 nm were formed via self-assembly upon precipitation in ethanolic solution. FISM nanoparticles were strongly fluorescent with maximum emission wavelength of 518 nm. The fluorescence of FISM nanoparticles can be quenched by silver (Ag+) and lead (Pb2+) ions in a concentration dependent manner. We have demonstrated the first use of FISM nanoparticles as cheap and effective fluorescent sensing probes for Ag+and Pb2+ions with detection limits as low as 2.55×10−5 M and 3.64×10−5 M, respectively.

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Sukprasong, Saksit, Yongyut Manjit, Apichart Limpichaipanit y Athipong Ngamjarurojana. "Inner Filter Effect on Fluorescence Dyes Spectra in Methanol Solution". Key Engineering Materials 675-676 (enero de 2016): 704–7. http://dx.doi.org/10.4028/www.scientific.net/kem.675-676.704.

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This research was conducted to study the inner filter effect on the fluorescence spectra of fluorescence dyes. The concentration effect on all of fluorescent dye solutions showed the same trend in terms of changes in fluorescence intensity spectra. At low concentrations, the fluorescence intensity increased when the concentration of fluorescent dye solution increased. However, at high concentrations, the fluorescence intensity decreased when the concentration of fluorescent dye solution increased. Interestingly, the result of fluorescence spectra in dye solutions showed that the fluorescence intensity maxima in all dye solutions were shifted to a higher wavelength (red-shift) when the concentration of fluorescent dye solution increased. The results of concentration effect on fluorescence intensity and wavelength-shift in dyes solution can be explained by inner filter effect on fluorescent dye solutions.

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Pang, Liaoliao, Jinfa Ming, Fukui Pan y Xin Ning. "Fabrication of Silk Fibroin Fluorescent Nanofibers via Electrospinning". Polymers 11, n.º 6 (4 de junio de 2019): 986. http://dx.doi.org/10.3390/polym11060986.

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Fluorescent silk fibroin nanofibers were fabricated via electrospinning method with three kinds of fluorescent dyes. Electrospun fluorescent nanofibers showed smooth surfaces and average diameters of 873 ± 135 nm, 835 ± 195 nm, and 925 ± 205 nm, respectively, for silk fibroin-fluorescein sodium, silk fibroin-rhodamine B, and silk fibroin-acridine orange nanofibers containing 2.0 wt% fluorescent dyes. At the same time, the secondary structure of silk fibroin in fluorescent nanofibers was predominantly amorphous conformation without influence by adding different concentrations of fluorescent dyes, as characterized by Fourier transform infrared spectroscopy and X-ray diffraction. Thermal degradation behavior of fluorescent silk fibroin nanofibers with a dramatic decrease in weight residue was observed at around 250 °C. The fluorescence effect of fluorescent silk fibroin nanofibers was changed by changing the concentration of different fluorescent dyes. These fluorescent nanofibers may make promising textile materials for large scale application.

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Zhang, Zhihong, Heping Zhu y Huseyin Guler. "Quantitative Analysis and Correction of Temperature Effects on Fluorescent Tracer Concentration Measurement". Sustainability 12, n.º 11 (2 de junio de 2020): 4501. http://dx.doi.org/10.3390/su12114501.

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To ensure an accurate evaluation of pesticide spray application efficiency and pesticide mixture uniformity, reliable and accurate measurements of fluorescence concentrations in spray solutions are critical. The objectives of this research were to examine the effects of solution temperature on measured concentrations of fluorescent tracers as the simulated pesticides and to develop models to correct the deviation of measurements caused by temperature variations. Fluorescent tracers (Brilliant Sulfaflavine (BSF), Eosin, Fluorescein sodium salt) were selected for tests with the solution temperatures ranging from 10.0 °C to 45.0 °C. The results showed that the measured concentrations of BSF decreased as the solution temperature increased, and the decrement rate was high at the beginning and then slowed down and tended to become constant. In contrast, the concentrations of Eosin decreased slowly at the beginning and then noticeably increased as temperatures increased. On the other hand, the concentrations of Fluorescein sodium salt had little variations with its solution temperature. To ensure the measurement accuracy, correction models were developed using the response surface methodology to numerically correct the measured concentration errors due to variations with the solution temperature. Corrected concentrations using the models agreed well with the actual concentrations, and the overall relative errors were reduced from 42.36% to 2.91% for BSF, 11.72% to 1.55% for Eosin, and 2.68% to 1.17% for Fluorescein sodium salt. Thus, this approach can be used to improve pesticide sprayer performances by accurately quantifying droplet deposits on target crops and off-target areas.

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Gogoleva, M. A., B. P. Yakimov, S. A. Rodionov, T. N. Tikhonova, Y. I. Gurfinkel, V. V. Fadeev, J. Lademann, M. E. Darvin y E. A. Shirshin. "Solid lipid curcumin-loaded particles for in vivo fluorescent imaging in humans: a proof of concept-=SUP=-*-=/SUP=-". Журнал технической физики 126, n.º 6 (2019): 809. http://dx.doi.org/10.21883/os.2019.06.47776.56-19.

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The possibility to use oral intake of fluorescent dyes approved on humans for intravital fluorescence in vivo imaging is attractive due to its simplicity and non-invasive character. Here we investigate the potential of solid lipid curcumin particles (SLCP) for imaging of capillary permeability using fluorescence video capillaroscopy. Curcumin fluorescence corresponding to 0.7 μg/ml concentration was observed from blood plasma after oral consumption of 2 g of SLCP. However, this signal was ~ 15% higher than that of blood plasma intrinsic fluorescence, which was itself at least 10-fold lower than the background signal from pericapillary tissue. By comparing the optical properties and concentration to the case of intravenous injection of sodium fluorescein, we analyzed which parameters of the experiment should be optimized for using oral consumption of fluorescing compounds in intravital in vivo capillaroscopy measurements.

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Ives, J. T. y W. M. Reichert. "Protein Adsorption on the Surface of a Thin-Film Polymer Integrated Optical Waveguide". Applied Spectroscopy 42, n.º 1 (enero de 1988): 68–72. http://dx.doi.org/10.1366/0003702884428572.

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Protein adsorption (fluorescein labeled gamma globulin, FITC-IgG) on the surface of poly(styrene) thin-film optical waveguides was fluorescently detected. The time course of adsorption, the FITC-IgG fluorescence spectra, and the surface concentration estimates are presented. The results demonstrate the potential use of polymer optical waveguides as integrated optic evanescent sensors.

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Nevidomskaya, Dina, Tatiana Minkina, Yuri Fedorov, Olga Nazarenko, Natalya Kravtsova y Yuri Litvinov. "Integral assessment of heavy metal pollution in Don River estuary soils". E3S Web of Conferences 169 (2020): 01007. http://dx.doi.org/10.1051/e3sconf/202016901007.

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Based on the cumulative pollution index, spatial distribution maps were obtained to establish categories of soil pollution taking into account the total content of heavy metals and the mobile forms of metals in the Don River estuarine region. The objects of the study included samples of zonal soils (Chernozem) and intrazonal soils (Fluvisols) from monitoring plots. The total concentrations of Mn, Cr, Ni, Cu, Zn, Pb, and Cd in the soils were determined by X-ray fluorescent scanning spectrometer. Mobile heavy metals compounds were transferred to a solution by extraction of 1 N NH4Ac, pH 4.8. When calculating the total metal content, it was shown the studied soils had generally an acceptable pollution category but taking into account mobile forms the categories of soils contamination variate up acceptable to extremely dangerous. The most polluted sites are associated with the estuary of small rivers and the branches flowing into the Taganrog Bay, the territory of the Taganrog port and its terminals, and road bridges. In line with hight categories of pollution, the use of the soils for cropping should be limited, and the cultivation of concentrator plants is excluded.

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Wang, Feifei, Roy P. Planalp y W. Rudolf Seitz. "A Cu(II) Indicator Platform Based on Cu(II) Induced Swelling that Changes the Extent of Fluorescein Self-Quenching". Polymers 11, n.º 12 (25 de noviembre de 2019): 1935. http://dx.doi.org/10.3390/polym11121935.

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In this study, we established a new fluorescent indicator platform. The responsive element consists of poly(N-isopropylacrylamide) nanospheres that include small percentages of fluorescein and a ligand, anilinodiacetate (phenylIDA). Nanosphere diameters were determined to be in the range from 50 to 90 nm by scanning electron microscopy. They were entrapped in a polyacrylamide gel to prevent nanosphere aggregation. At pH 6, the ligand is negatively charged in the absence of metal ions. Charge-charge repulsion causes the nanosphere to swell. Dynamic light scattering measurements show that these nanospheres do not shrink and aggregate at high temperature. Cu(II) binding neutralizes the charge causing the particles to shrink. This brings fluoresceins closer together, increasing the degree of self-quenching. The intensity decreases by 30% as Cu(II) concentration increases. To rule out the possibility that the observed decrease in intensity was due to Cu(II) quenching of fluorescence, we also added Zn(II) and observed a decrease in intensity. This approach can be adapted to sense different metal ions and different concentrations of Cu(II) by changing the ligand.

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Ardon, Orly, Raphael Nudelman, Catherine Caris, Jacqueline Libman, Abraham Shanzer, Yona Chen y Yitzhak Hadar. "Iron Uptake in Ustilago maydis: Tracking the Iron Path". Journal of Bacteriology 180, n.º 8 (15 de abril de 1998): 2021–26. http://dx.doi.org/10.1128/jb.180.8.2021-2026.1998.

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ABSTRACT In this study, we monitored and compared the uptake of iron in the fungus Ustilago maydis by using biomimetic siderophore analogs of ferrichrome, the fungal native siderophore, and ferrioxamine B (FOB), a xenosiderophore. Ferrichrome-iron was taken up at a higher rate than FOB-iron. Unlike ferrichrome-mediated uptake, FOB-mediated iron transport involved an extracellular reduction mechanism. By using fluorescently labeled siderophore analogs, we monitored the time course, as well as the localization, of iron uptake processes within the fungal cells. A fluorescently labeled ferrichrome analog, B9-lissamine rhodamine B, which does not exhibit fluorescence quenching upon iron binding, was used to monitor the entry of the compounds into the fungal cells. The fluorescence was found intracellularly 4 h after the application and later was found concentrated in two to three vesicles within each cell. The fluorescence of the fluorescently labeled FOB analog CAT18, which is quenched by iron, was visualized around the cell membrane after 4 h of incubation with the ferrated (nonfluorescent) compounds. This fluorescence intensity increased with time, demonstrating fungal iron uptake from the siderophores, which remained extracellular. We here introduce the use of fluorescent biomimetic siderophores as tools to directly track and discriminate between different pathways of iron uptake in cells.

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Olson, Kenneth R., Yan Gao, Faihaan Arif, Kanika Arora, Shivali Patel, Eric DeLeon y Karl D. Straub. "Fluorescence quenching by metal centered porphyrins and poryphyrin enzymes". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 313, n.º 4 (1 de octubre de 2017): R340—R346. http://dx.doi.org/10.1152/ajpregu.00202.2017.

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Fluorescence spectroscopy and microscopy have been used extensively to monitor biomolecules, especially reactive oxygen species (ROS) and, more recently, reactive sulfide (RSS) species. Nearly all fluorophores are either excited by or emit light between 450 and 550 nm, which is similar to the absorbance of heme proteins and metal-centered porphyrins. Here we examined the effects of catalase (Cat), reduced and oxidized hemoglobin (Hb and metHb), albumin (alb), manganese (III) tetrakis (4-benzoic acid) porphyrin chloride (MnTBAP), iron protoporphyrin IX (hemin), and copper protoporphyrin IX (CuPPIX) on the fluorescence properties of fluorescein. We also examined the effects of catalase and MnTBAP on fluorophores for ROS (dichlorofluorescein, DCF), polysulfides (3′,6′-di( O-thiosalicyl)fluorescein, SSP4), and H2S (7-azido-4-methylcoumarin, AzMC) previously activated by H2O2, a mixed polysulfide (H2Sn, n = 1–7) and H2S, respectively. All except albumin concentration dependently inhibited fluorophore fluorescence and absorbed light between 450 and 550 nm, suggesting that the inhibitory effect was physical not catalytic. Catalase inhibition of fluorescein fluorescence was unaffected by sodium azide, dithiothreitol, diamide, tris(2-carboxyethyl)phosphine (TCEP), or iodoacetate, supporting a physical inhibitory mechanism. Catalase and TBAP augmented, then inhibited DCF fluorescence, but only inhibited SSP4 and AzMC fluorescence indicative of a substrate-specific catalytic oxidation of DCF and nonspecific fluorescence inhibition of all three fluorophores. These results suggest caution must be exercised when using any fluorescent tracers in the vicinity of metal-centered porphyrins.

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Liu, Jing. "A Study of the Optical Properties of Triazene-Cinnamic Acid Polymeric Fluorescent Brighteners". Applied Mechanics and Materials 184-185 (junio de 2012): 868–71. http://dx.doi.org/10.4028/www.scientific.net/amm.184-185.868.

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Series of the triazene-cinnamic acid polymeric fluorescent brighteners were synthesized through three-step condensation reactions and polymerization reaction with styrene under replacing one of amino compounds of traditional fluorescent brighteners by cinnamic acid. The optical properties in aqueous solutions and N,N’- dimethyl formamide as well as paper coating application test were evaluated. The results showed that the light stability and fluorescence quantum yield of polymeric fluorescent brighteners was improved obviously and photoinduced isomerization was lower. Meanwhile the optical properties of polymeric fluorescent brightener were affected by concentration and solvent polarity, fluorescence quantum yield increasing and hypochromatic shift of fluorescence emmission wavelength with the decrease of solvent polarity. When the concentration was over 1 10-4 g/mL, the fluorescence was quenched.

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Suzuki, Takeshi, Keiko Fujikura, Tetsuya Higashiyama y Kuniaki Takata. "DNA Staining for Fluorescence and Laser Confocal Microscopy". Journal of Histochemistry & Cytochemistry 45, n.º 1 (enero de 1997): 49–53. http://dx.doi.org/10.1177/002215549704500107.

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We examined five nucleic acid binding fluorescent dyes, propidium iodide, SYBR Green I, YO-PRO-1, TOTO-3, and TO-PRO-3, for nuclear DNA staining, visualized by fluorescence and laser confocal microscopy. The optimal concentration, co-staining of RNA, and bleaching speeds were examined. SYBR Green I and TO-PRO-3 almost preferentially stained the nuclear DNA, and the other dyes co-stained the cytoplasmic RNA. RNAse treatment completely prevented the cytoplasmic RNA staining. In conventional fluorescence microscopy, these dyes can be used in combination with fluorescence-labeled antibodies. Among the dyes tested, TOTO-3 and TO-PRO-3 stained the DNAs with far-red fluorescence under red excitation. Under Kr/Ar-laser illumination, TOTO-3 and TO-PRO-3 were best suited as the nuclear staining dyes in the specimens immunolabeled with fluorescein and rhodamine (or Texas red).

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38

Jiao, Chun Lian, Yun Fang Wu, Chun Yang Hou, Guo Chen Cheng, Dong Xia Wu, Xu Xu y Jian Hua Yin. "Determine the Consumption of Fluorescent Scale Inhibitor SC260 Using Dibenzofuran-2-Sulfonic Acid Hydrate". Advanced Materials Research 997 (agosto de 2014): 247–50. http://dx.doi.org/10.4028/www.scientific.net/amr.997.247.

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Fluorescence spectra and signal stability of the fluorescent scale inhibitor SC260 and dibenzofuran-2-sulfonic acid hydrate in deionized water and in seawater concentration experiment were described. There was no impact on respective excitation and emission peaks of each other and the change of fluorescence intensity was no more than 5%. The relationship between fluorescence intensity and concentration of SC260 and BFN were linear. Because the fluorescence signals of SC260 and BFN were stable in seawater concentration experiment, the consumption of fluorescent inhibitor SC260 in seawater was studied.

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39

Yamada, K., A. Moriguchi, R. Morishita, M. Aoki, Y. Nakamura, H. Mikami, T. Oshima et al. "Efficient oligonucleotide delivery using the HVJ-liposome method in the central nervous system". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 271, n.º 5 (1 de noviembre de 1996): R1212—R1220. http://dx.doi.org/10.1152/ajpregu.1996.271.5.r1212.

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We examined the efficiency and intracellular fate of oligodeoxy-nucleotides (ODN) in the central nervous system (CNS) after delivery with a hemagglutinating virus of Japan (HVJ)-liposome vector in vivo and in vitro. In primary cultured granular cells of the rat cerebellum, application of fluorescein isothiocyanate (FITC)-labeled ODN complexed with HVJ-liposomes in vitro resulted in strong fluorescence localized in nuclei that persisted for > or = 2 wk, in contrast to 3 days with ODN alone. In vivo ODN transfer was attempted by different approaches: infusions into the paraventricular nuclei of the hypothalamus and the lateral cerebroventricle. Injection of FITC-labeled ODN into the hypothalamus by the HVJ-liposome method produced a higher concentration and more persistent fluorescence than did injection of ODN alone. Administration of ODN into the lateral cerebroventricle with HVJ-liposomes yielded more conspicuous and prolonged fluorescence in the periventricular layer, predominantly in cell nuclei. Furthermore, the distribution of fluorescent cells was broader with the HVJ-liposome method. These results indicate that the HVJ-liposome method prolongs the half-life of ODN and concentrates them in cell nuclei. Thus it is an efficient method for ODN transfer and holds promise as a gene delivery method in the CNS.

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Nakata, Eiji, Khongorzul Gerelbaatar, Futa Komatsubara y Takashi Morii. "Stimuli-Responsible SNARF Derivatives as a Latent Ratiometric Fluorescent Probe". Molecules 27, n.º 21 (24 de octubre de 2022): 7181. http://dx.doi.org/10.3390/molecules27217181.

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Fluorescence imaging is a powerful technique for continuous observation of dynamic intracellular processes of living cells. Fluorescent probes bearing a fluorescence switching property associated with a specific recognition or reaction of target biomolecule, that is, stimuli-responsibility, are important for fluorescence imaging. Thus, fluorescent probes continue to be developed to support approaches with different design strategies. When compared with simple intensity-changing fluorescent probes, ratiometric fluorescent probes typically offer the advantage of less sensitivity to errors associated with probe concentration, photobleaching, and environmental effects. For intracellular usage, ratiometric fluorescent probes based on small molecules must be loaded into the cells. Thus, probes having intrinsic fluorescence may obscure a change in intracellular signal if the background fluorescence of the remaining extracellular probes is high. To overcome such disadvantages, it is necessary to minimize the extracellular background fluorescence of fluorescent probes. Here, the design strategy of the latent ratiometric fluorescent probe for wash-free ratiometric imaging using a xanthene dye seminapthorhodafluor (SNARF) as the scaffold of fluorophore is discussed.

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41

Soto, Dagoberto, Camila Silva, Cristian Ugalde, Kwok-Yin Wong, Yun-Chung Leung, Lok-Yan So y Max Andresen. "Effect of Lactamase Inhibitors on the Biosensor Penp during the Measurement of Lactam Antibiotics Concentration". Sensors 19, n.º 5 (12 de marzo de 2019): 1237. http://dx.doi.org/10.3390/s19051237.

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PenP is a fluorescent biosensor of lactam antibiotics (LA). It is structurally derived from the mutant lactamase TEM-1 comprising the substitution E166C, where fluorescein is covalently linked to cysteine. The presence of LA in the medium produces a change in the intrinsic fluorescence level of the biosensor, and the integral of the fluorescence level over time correlates directly with the LA concentration. Previously, we have successfully used PenP to determine the concentration of lactam antibiotics in clinical samples. The use of lactamase inhibitors (LI) is a common strategy to enhance the effect of LA due to the inhibition of an important resistance mechanism of pathogenic microorganisms. Structurally, LI and LA share the common element of recognition of lactamases (the lactam ring), but they differ in the reversibility of the mechanism of interaction with said enzyme. Because the biological recognition domain of PenP is derived from a lactamase, LI is expected to interfere with the PenP detection capabilities. Surprisingly, this work provides evidence that the effect of LI is marginal in the determination of LA concentration mediated by PenP.

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42

Poole, C. A., N. H. Brookes y G. M. Clover. "Keratocyte networks visualised in the living cornea using vital dyes". Journal of Cell Science 106, n.º 2 (1 de octubre de 1993): 685–91. http://dx.doi.org/10.1242/jcs.106.2.685.

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Fluorescent viability probes have been used to visualise and investigate the viability, morphology and organisation of the keratocyte within the stroma of the intact living cornea. The live cell probe, calcien-AM, in combination with a dead cell probe, ethidium homodimer (Live/Dead Assay, Molecular Probes, U.S.A.) proved superior to earlier generation vital dyes such as fluorescein diacetate or 5,6-carboxyfluorescein diacetate, initially used in combination with ethidium bromide. The ubiquitous distribution of esterase enzymes that cleave calcien-AM within the keratocyte cytoplasm produced a high concentration of fluorescently active calcein throughout the cell, including fine cell processes. Epi-illuminated fluorescence microscopy on transparent corneal dissections subsequently revealed details of keratocyte microanatomy and three-dimensional network organisation in situ. Three morphologically discrete subpopulations of keratocytes were identified: two formed relatively small bands of cells, immediately subjacent to either Bowman's or Descemet's membranes, the third subpopulation constituting the majority of keratocytes typically located within the corneal stroma. The results indicate that calcein-AM is able to penetrate intact living cornea revealing cell viability, and it also has the capacity to ‘trace’ cellular elements and reveal fine structure within a dense connective tissue matrix.

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Włodarski, Jakub y Miłosz Chychłowski. "Chemically tuned light source with an optical pump". Photonics Letters of Poland 13, n.º 2 (30 de junio de 2021): 46. http://dx.doi.org/10.4302/plp.v13i2.1101.

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This article presents the latest results of rhodamine B and fluorescein solutions emissions at different weight concentrations. The shift of emitted central peak wavelength is observed to change in weight concentrations of the active material in samples. By using only two active materials photoluminescence at desired wavelength form range 524nm – 660nm can be achieved. All samples were excited sequentially by a laser source and two blue light-emitting diodes without significant changes in the emitted spectra. Full Text: PDF ReferencesJ. R. Lakowicz, Principles of Fluorescence Spectroscopy. Springer Science & Business Media, Pages 1-6, (2013). CrossRef R. Sjöback, J. Nygren, M. Kubista, "Absorption and fluorescence properties of fluorescein", Spectrochimica Acta Part A: Molecular Spectroscopy, Volume 51, L7-L21, (1995) CrossRef M. F. Al-Kadhemy, I. F. Alsharuee, A. A. D. Al-Zuky, "Analysis of the effect of the concentration of rhodamine B in ethanol on the fluorescence spectrum using the 'Gauss Mod'function", Journal of Physical Science, 22(2), 77-86, (2011). DirectLink F. M. Zehentbauer, et al., "Fluorescence spectroscopy of Rhodamine 6G: Concentration and solvent effects", Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 121, 147-151, (2014) CrossRef M. F. H. Al-Kadhemy, A. A. D. Al-Zuky, H. F. Daear, "Theoretical Model for the Effect of Temperature on the Fluorescence Spectrum of Laser Dye (Rh6G) in Acetone", International Letters of Chemistry, Physics and Astronomy, 19, (2014). CrossRef A. H.Al-Hamdani, S. M. Jasim, E. M. Abbas, D. A. Hassan, M. M. Jaber, "Spectral Properties of Hybrid of Rhodamine (6G) Dyes Doped Epoxy Resin Dissolved in Chloroform", Baghdad Science Journal, 16(3 Supplement), 764-769, (2019). http://dx.doi.org/10.21123/bsj.2019.16.3(Suppl.).0764 CrossRef M. F. Al-Kadhemy, I. F. Alsharuee, A. A. D. Al-Zuky, "Analysis of the effect of the concentration of rhodamine B in ethanol on the fluorescence spectrum using the 'Gauss Mod'function", Journal of Physical Science, 22(2), 77-86, (2011). DirectLink C. Bojarski, G. Żurkowska, J. Tyrzyk, "The Concentrational Changes of the Fluorescence Decay Time of Rhodamine B in Ethanol", Zeitschrift für Naturforschung A, vol. 37, no. 1, 74-77, (1982) CrossRef M. F. Al-Kadhemy, A. Al-Zuky, I. F. Al-Sharuee, "Theoretical Model to Study the Effect of Concentration and Impurities on the Fluorescence Spectrum of Fluorescein Solution in Ethanol using Fourier Series 3× 2", International Journal of Materials Physics, 2, 75-86, (2011). DirectLink D. V. Vezenov, B. T. Mayers, D. B. Wolfe, G. M. Whitesides, "Integrated fluorescent light source for optofluidic applications", Applied Physics Letters, volume 86, 041104, (2005) CrossRef V. P. Vladev, T. A. Eftimov, W. J. Bock, "Broad-band fluorescent all-fiber source based on microstructured optical fibers", Phot. Lett. Pol., vol. 7, no. 2, 41-43, (2015) CrossRef J. Żmojda, P. Miluski, M. Kochanowicz, J. Dorosz, A. Baranowska, M. Leśniak, D. Dorosz, "Luminescent properties of active optical fibers", Phot. Lett. Pol., vol. 11, CrossRef

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An, Yulong, Can Liu, Yan Li, Menglin Chen, Yunwu Zheng, Hao Tian, Rui Shi, Xiahong He y Xu Lin. "Application of high-efficiency green fluorescent carbon dots prepared by acid catalysis in multicolour LEDs". RSC Advances 11, n.º 60 (2021): 38033–39. http://dx.doi.org/10.1039/d1ra07280c.

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Green fluorescent CDs prepared by acid catalysis with m-phenylenediamine showed concentration dependent fluorescence. Green, yellow and white LEDs were prepared according to the concentration dependent fluorescence characteristics of CDs.

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45

Liu, Xuemei, Kieran J. Germaine, David Ryan y David N. Dowling. "DEVELOPMENT OF A GFP‐BASED BIOSENSOR FOR DETECTING THE BIOAVAILABILITY AND BIODEGRADATION OF POLYCHLORINATED BIPHENYLS (PCBS)". JOURNAL OF ENVIRONMENTAL ENGINEERING AND LANDSCAPE MANAGEMENT 15, n.º 4 (31 de diciembre de 2007): 261–68. http://dx.doi.org/10.3846/16486897.2007.9636939.

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Two whole-cell biosensors were constructed to detect the in situ biodegradation of polychlorinated biphenyl by chromosomal insertion of a mini‐Tn5‐Kmr‐Pm::gfp[mut3]‐T0‐T1 construct into P. fluorescens. In vitro tests showed that the expression of the Pm promoter depended on the growth phase of the biosensors and the concentration of chemical inducers; chlorinated benzoic acid derivatives. A linear relationship between the fluorescent intensity and the log10 concentration of the inducer was observed. One biosensor (F113L::1180gfp) had the ability to degrade PCBs to relevant chlorobenzoic acid derivatives and to induce expression of Gfp. The second biosensor (F113gfp), which cannot degrade PCBs, shows fluorescence after induction by chloro‐benzoic acid derivatives. By using these two biosensors, PCB degradation could be detected in vitro and in soil.

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46

Rivers, Richard J., Judy B. Beckman y Mary D. S. Frame. "Technique for Using Video Microscopy and Indicator Dilution for Repeated Measurements of Cardiac Output in Small Animals". Anesthesiology 94, n.º 3 (1 de marzo de 2001): 489–95. http://dx.doi.org/10.1097/00000542-200103000-00021.

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Background The authors developed an indicator dilution technique for small animals to repeatedly determine cardiac output and blood volume without cardiac instrumentation or blood sampling. Methods Observations were made in the hamster (N = 32, 70 mg/kg pentobarbital) cremaster using in vivo fluorescence videomicroscopy. Fluorescein isothiocyanate-conjugated bovine serum albumin (10 mg/ml) was injected as a bolus dose (right jugular) while video recording the light intensity in a 20-microm arteriole (intensified charge-coupled device [CCD] camera at fixed gain). The intensity signal was analyzed over time (background subtracted) and calibrated to the dye concentration. The ex vivo calibration was performed using a constant optical path length (20 microm) and a range of dye and hematocrit concentrations. In vivo tube hematocrit was determined using standard methods with fluorescently labeled erythrocytes. Thus, quenching of the fluorescence signal by hemoglobin was corrected for the calibration, and the plasma space in the arteriole was determined. The steady state dye concentration measured by the light intensity at 2 min was not different from the dye concentration found by direct spectrophotometric analysis of the plasma. Results Cardiac index was calculated as milliliters of blood per minute per kilogram body weight. The calculated cardiac index was 359 +/- 18 ml.min(-1).kg(-1), which is not different from the reported values for hamsters. Cardiac output was increased twofold when enough intravenous nitroprusside or nitroglycerine was injected to decrease mean arterial pressure from 90 to 70 mmHg. Cardiac output was elevated during dobutamine infusion (16 microg.kg(-1).min(-1)) and decreased during esmolol infusion (50, 75.kg(-1).min(-1)). Blood volume determined from the steady state dye concentrations was 6.2 +/- 0.5 ml/100 g body weight, within the normal range for hamsters. Conclusions Fluorescent dye dilution and video microscopy can be used to repeatedly determine cardiac output or blood volume in small animals.

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Zhu, Xianwei y Hiroaki Shinohara. "Fluorescence Enhancement of Fluorescent Unnatural Streptavidin by Binding of a Biotin Analogue with Spacer Tail and Its Application to Biotin Sensing". Scientific World Journal 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/165369.

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We designed a novel molecular biosensing system for the detection of biotin, an important vitamin by the combination of fluorescent unnatural streptavidin with a commercialized biotin-(AC5)2-hydrazide. A fluorescent unnatural amino acid, BODIPY-FL-aminophenylalanine (BFLAF), was position-specifically incorporated into Trp120 of streptavidin by four-base codon method. Fluorescence of the Trp120BFLAF mutant streptavidin was enhanced by the addition of biotin-(AC5)2-hydrazide with the concentration dependent, whereas fluorescence enhancement was not observed at all by the addition of natural biotin. It was considered that the spacer tail of biotin-(AC5)2-hydrazide may disturb the fluorescence quenching of the Trp120BFLAF by Trp79 and Trp108 of the neighbor subunit. Therefore, biotin sensing was carried out by the competitive binding reaction of biotin-(AC5)2-hydrazide and natural biotin to the fluorescent mutant streptavidin. The fluorescence intensity decreased by increasing free biotin concentration. The result suggested that molecular biosensor for small ligand could be successfully designed by the pair of fluorescent mutant binding protein and ligand analogue.

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48

Stiner, Lawrence y Larry J. Halverson. "Development and Characterization of a Green Fluorescent Protein-Based Bacterial Biosensor for Bioavailable Toluene and Related Compounds". Applied and Environmental Microbiology 68, n.º 4 (abril de 2002): 1962–71. http://dx.doi.org/10.1128/aem.68.4.1962-1971.2002.

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ABSTRACT A green fluorescent protein-based Pseudomonas fluorescens strain A506 biosensor was constructed and characterized for its potential to measure benzene, toluene, ethylbenzene, and related compounds in aqueous solutions. The biosensor is based on a plasmid carrying the toluene-benzene utilization (tbu) pathway transcriptional activator TbuT from Ralstonia pickettii PKO1 and a transcriptional fusion of its promoter PtbuA1 with a promoterless gfp gene on a broad-host-range promoter probe vector. TbuT was not limiting, since it was constitutively expressed by being fused to the neomycin phosphotransferase (nptII) promoter. The biosensor cells were readily induced, and fluorescence emission after induction periods of 3 h correlated well with toluene, benzene, ethylbenzene, and trichloroethylene concentrations. Our experiments using flow cytometry show that intermediate levels of gfp expression in response to toluene reflect uniform induction of cells. As the toluene concentration increases, the level of gfp expression per cell increases until saturation kinetics of the TbuT-PtbuA1 system are observed. Each inducer had a unique minimum concentration that was necessary for induction, with K app values that ranged from 3.3 ± 1.8 μM for toluene to 35.6 ± 16.6 μM for trichloroethylene (means ± standard errors of the means), and maximal fluorescence response. The fluorescence response was specific for alkyl-substituted benzene derivatives and branched alkenes (di- and trichloroethylene, 2-methyl-2-butene). The biosensor responded in an additive fashion to the presence of multiple inducers and was unaffected by the presence of compounds that were not inducers, such as those present in gasoline. Flow cytometry revealed that, in response to toxic concentrations of gasoline, there was a small uninduced population and another larger fully induced population whose levels of fluorescence corresponded to the amount of effectors present in the sample. These results demonstrate the potential for green fluorescent protein-based bacterial biosensors to measure environmental contaminants.

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Mukhametova, Lilia I., Sergei A. Eremin, Dmitrii A. Arutyunyan, Oksana S. Goryainova, Tatiana I. Ivanova y Sergei V. Tillib. "Fluorescence Polarization Immunoassay of Human Lactoferrin in Milk Using Small Single-Domain Antibodies". Biochemistry (Moscow) 87, n.º 12-13 (diciembre de 2022): 1679–88. http://dx.doi.org/10.1134/s0006297922120227.

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Abstract Due to its unique structure and properties, human breast milk lactoferrin (hLF) has many nutritional and health-promoting functions in infants, including protection against inflammation and bacterial infections. The lack of LF in breastmilk or formula can result in the weakening of the infant’s immune system. Noncompetitive polarization fluorescence immunoassay (FPIA) is a promising method for hLF quantification in milk and dairy products, which does not require the separation of the bound and free protein and allows to avoid time-consuming sample preparation. The use of fluorescently labeled single-domain camelid antibodies (nanobodies) for protein recognition in FPIA makes it possible to quantify relatively large antigens, in particular, hLF. In this work, we used previously obtained fluorescein isothiocyanate (FITC)-conjugated anti-hLF5 and anti-hLF16 nanobodies, which selectively recognized two different human lactoferrin epitopes, but did not bind to goat lactoferrin. The kinetics of hLF interaction with the FITC-labeled nanobodies was studied. The dissociation constant (KD) for the anti-LF5 and anti-LF16 nanobodies was 3.2 ± 0.3 and 4.9 ± 0.4 nM, respectively, indicating the high-affinity binding of these nanobodies to hLF. We developed the FPIA protocol and determined the concentration of FITC-labeled anti-hLF5 and anti-hLF16 nanobodies that provided the optimal fluorescence signal and stable fluorescence polarization value. We also studied the dependence of fluorescence polarization on the hLF concentration in the noncompetitive FPIA with FITC-anti-hLF5 nanobody. The detection limit for hLF was 2.1 ± 0.2 µg/ml and the linear range for determining the hLF concentration was 3-10 µg/ml. FPIA is commonly used to assay low-molecular-weight substances; however, the use of fluorescently labeled nanobodies allows quantification of high-molecular-weight proteins. Here, we demonstrated that FPIA with fluorescently labeled nanobodies can be used for hLF quantification in milk.

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Milićević, David y Jan Hlaváč. "Immobilized Fluorescent Probes for Simultaneous Multiple Protease Detection". Chemosensors 9, n.º 6 (24 de mayo de 2021): 119. http://dx.doi.org/10.3390/chemosensors9060119.

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A new concept for simultaneous detection of two model proteases based on immobilized fluorescently labelled peptides was developed and evaluated. Each probe was composed of a carrier modified by poly(ethylene glycol) (PEG) chains, a specifically cleavable linker, and a fluorescent dye incorporated in the peptide tail. Based on a single excitation–double emission fluorescence response of liberated fluorophores caused by enzymatic cleavage, the presence of a single or both proteases in a mixture was unambiguously determined in an experimentally established concentration range. Among the tested solid supports, Rink Amide PEGA resin was recognized as the most suitable choice from the perspective of on-resin enzyme assays.

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