Articles de revues : « Fluorescenza X »

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Li, Ping, Yanhui Song, Xufeng Niu, Kun Li et Yubo Fan. « Drug Delivery System with Multiple Rare Earth Ions Fluorescent-Labeling Drugs and Magnetic Nanoparticles ». Journal of Nanoscience and Nanotechnology 19, n^o 6 (1 juin 2019) : 3288–92. http://dx.doi.org/10.1166/jnn.2019.16578.

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The bifunctional drug delivery system combining magnetic nanoparticles and fluorophore possesses the characterization of magnetism and fluorescence. However, the accurate tracing of the drug release and diffusion pathway is affected by the separation of drug and fluorescent molecule. In this paper, we synthesized the fluorescent-labeling drug by covalently binding Aspirin with rare earth ions Terbium (Te) and Gadolinium (Gd), which was incorporated into chitosan microspheres with magnetic nanoparticles Fe3O4 to prepare magnetic and fluorescent drug delivery system. Investigated by Fourier transform infrared spectrometer, fluorescence spectrophotometer, X-ray diffraction, vibrating sample magnetometer, and scanning electron microscopy, the chitosan microspheres showed excellent fluorescent and magnetic properties. Compared with the single rare earth ion complex, the multiple rare earth ions complexes with Aspirin TbxGd1−x(Aspirin)3 · 2H2O (x 0.25, 0.5, 0.75) exhibited superior fluorescent intensity.

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Zhuo, Wei. « Design of X-Ray Fluorescence Spectrum Software Based on Linux ». Applied Mechanics and Materials 602-605 (août 2014) : 3601–3. http://dx.doi.org/10.4028/www.scientific.net/amm.602-605.3601.

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According to the research on analysis software of X fluorescent spectrum under the Linux system, a new algorithm of X fluorescence analyzer has been brought up: use the method of energy dispersive X fluorescence analysis, based on the software that can analyze the material composition under the control of ARM - Linux touch screen. This paper fixes on developing software of X fluorescence analyzer; realize the collection and analysis of multi-channel spectrum data, data storage, sample analysis, qualitative and quantitative analysis of the on-site samples, and the research and implementation of corresponding algorithm.

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Han, I., M. Şahin et L. Demir. « Angular variations of K and L X-ray fluorescence cross sections for some lanthanides ». Canadian Journal of Physics 86, n^o 2 (1 février 2008) : 361–67. http://dx.doi.org/10.1139/p07-128.

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Kα, Kβ, Lα, and Lβ X-ray fluorescence cross sections for lanthanides in the atomic range 62 ≤ Z ≤ 68 (Sm, Eu, Gd Tb, Dy, Ho, and Er) were simultaneously measured by 59.54 keV incident photon energy at five angles ranging from 120° to 160°. The measurements were performed using an Am-241 radioisotope as the photon source and a Si(Li) detector. The Lα X-ray fluorescence cross section (σLα) was found to decrease with increasing emission angle and showed an anisotropic distribution of Lα X-rays. Kα, Kβ, and Lβ X-ray fluorescence cross sections (σKα, σKβ, and σLβ) were observed to be angle-independent and showed an isotropic distribution of Kα, Kβ, and Lβ X-rays. The Kα and Kβ X-rays originate from filling of the K shell (J = 1/2) vacancies, Lβ X-rays from filling of the L1 and L2 (J = 1/2) subshell vacancies, and Lα X-rays from filling of the L3 subshell (J = 3/2) vacancy. The fluorescent X-rays originating from the vacancy states with J = 1/2 are isotropic and unpolarized, but fluorescent X-rays originating from the vacancy states with J > 1/2 are anisotropic and polarized. Thus, the atomic inner shells vacancy states with J > 1/2 are aligned whereas vacancy states with J = 1/2 are not aligned. Lα fluorescence X-rays have an anisotropic distribution, while Kα, Kβ, and Lβ fluorescence X-rays have isotropic distribution. Furthermore, the IKβ/IKα, ILα/IKα}, ILβ/IKα, and ILβ/ILα intensity ratios for the elements under investigation were determined. The experimental cross sections and intensity ratios for Kα, Kβ, Lα, and Lβ fluorescence X-rays were also determined, and these experimental values were compared with our calculated theoretical values.PACS Nos.: 32.30.Rj, 32.80.Cy

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Yamada, Shoya, Fuminori Ohsawa, Shuji Fujii, Ryosuke Shinozaki, Makoto Makishima, Hirotaka Naitou, Shuichi Enomoto, Akihiro Tai et Hiroki Kakuta. « Fluorescent retinoid X receptor ligands for fluorescence polarization assay ». Bioorganic & ; Medicinal Chemistry Letters 20, n^o 17 (septembre 2010) : 5143–46. http://dx.doi.org/10.1016/j.bmcl.2010.07.011.

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Vincze, L., K. Janssens et F. Adams. « Optics for X-ray Microfluorescence to Be Used at the European Synchrotron Radiation Facility ». Advances in X-ray Analysis 37 (1993) : 553–63. http://dx.doi.org/10.1154/s0376030800016104.

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Micro-SRXRF (Synchrotron Radiation induced X-ray Fluorescence) is ti microanalytical technique which, utilizes an intense, polarized X-ray micro beam originating from the storage ring to induce X-ray fluorescence in a microscopic volume of the sample under investigation. The emerging fluorescent and scattered radiation is normally detected by an energy-dispersive Si(Li) detector. The recorded fluorescent spectra provide qualitative and quantitative information on the examined material yielding minimum, detection limits in the ppm and in favourable cases in the sub-ppm range at current SRXRF-facilities. Possible applications of synchrotron X-ray microprobes are the mapping of chemical elements in biological tissues, investigation of element migration and partitioning in geological systems, the analysis of individual microscopic particles and a variety of topics in applied research.

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Heck, Susanne, Olga Ermakova, Hiromi Iwasaki, Koichi Akashi, Chiao-Wang Sun, Thomas M. Ryan, Tim Townes et Thomas Graf. « Distinguishable live erythroid and myeloid cells in β-globin ECFP x lysozyme EGFP mice ». Blood 101, n^o 3 (1 février 2003) : 903–6. http://dx.doi.org/10.1182/blood-2002-06-1861.

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Abstract We previously described a mouse line that contains green myelomonocytic cells due to the knock-in of enhanced green fluorescence protein (EGFP) into the lysozyme M gene.1 We have now created a transgenic line with fluorescent erythroid cells using a β-globin locus control region driving the enhanced cyan fluorescence protein (ECFP) gene. These mice exhibit cyan fluorescent cells specifically in the erythroid compartment and in megakaryocyte-erythroid progenitors. Crossing the animals with lysozyme EGFP mice yielded a line in which live erythroid and myeloid cells can readily be distinguished by fluorescence microscopy and by fluorescence-activated cell-sorter scanner. This cross allowed unambiguous identification of unstained mixed erythroid-myeloid colonies for the first time. The new mouse lines should become useful tools to dissect the branching between erythroid and myelomonocytic cells during in vitro differentiation of definitive multipotent progenitors.

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Che, Zhijiang, Jian Zhang, Baiyi Wu, Qiangqiang Hu, Wenxiang Mu, Yanru Yin et Zhitai Jia. « Investigation of Y2.1Er0.9(ScxGa1−x)5O12 Matrix Components on the Spectral Properties around 3.0 μm by Micro-Pulling-Down Method ». Crystals 9, n^o 3 (7 mars 2019) : 138. http://dx.doi.org/10.3390/cryst9030138.

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Single crystal fibers of 30% Er3+-doped compound of Y3(ScxGa1−x)5O12 have been grown by using the micro-pulling down (μ-PD) technique successfully. Our main purpose is to tune the fluorescence properties by adjusting the ratios of Sc3+ and Ga3+ ions inside the matrix crystals. The crystal structures of the series compounds were measured and analyzed through X-ray diffraction (XRD) measurements. The components and doping elements distributions were measured by the X-ray Fluorescence spectrometry and electron-probe microanalyzer. The absorption and mid-infrared fluorescence spectra, including the fluorescent lifetime of Er3+:4I13/2 and 4I11/2 levels were measured and compared systematically at room temperature. Spectral analysis indicated that the fluorescent lifetime of Er3+:4I13/2 tended to shorten and the emission spectra began to show a red shift when the proportion of YSG increased in the compound. Furthermore, the Raman spectra were measured to reveal the variations of lattice vibration and phonon energy.

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Hu, Sheng-Li, Guo-Dong Yin, Yu-Zhou Wang et An-Xin Wu. « Synthesis, X-ray structure, and binding properties of a new fluorescent molecular clip derived from diethoxycarbonyl glycoluril ». Canadian Journal of Chemistry 86, n^o 7 (1 juillet 2008) : 691–94. http://dx.doi.org/10.1139/v08-058.

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A new fluorescent molecule clip derived from diethoxycarbonyl glycoluril with two 2,5-diphenyl-furan sidewalls was designed and synthesized. Its structure and conformation was confirmed by single-crystal X-ray diffraction. Its binding properties, investigated by fluorescence spectroscopey, showed that it can selectively bind Fe3+ with fluorescence quenching.Key words: diethoxycarbonyl glycoluril, molecular clip, fluorescence, Fe(III).

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Khanra, Somnath, Sabyasachi Ta, Milan Ghosh, Sudeshna Chatterjee et Debasis Das. « Subtle structural variation in azine/imine derivatives controls Zn2+ sensitivity : ESIPT-CHEF combination for nano-molar detection of Zn2+ with DFT support ». RSC Advances 9, n^o 37 (2019) : 21302–10. http://dx.doi.org/10.1039/c9ra03652k.

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Gabey, A. M., W. R. Stanley, M. W. Gallagher et P. H. Kaye. « The fluorescence properties of aerosol larger than 0.8 μm in an urban and a PBA-dominated location ». Atmospheric Chemistry and Physics Discussions 11, n^o 1 (7 janvier 2011) : 531–66. http://dx.doi.org/10.5194/acpd-11-531-2011.

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Abstract. Dual-wavelength Ultraviolet light-induced fluorescence (UV-LIF) measurements were performed on ambient environmental aerosol in Manchester, UK (urban city centre, winter) and Borneo, Malaysia (remote, tropical), which are taken to represent environments with negligible and significant primary biological aerosol (PBA) influences, respectively. Single-particle fluorescence intensity and optical equivalent diameter were measured with a Wide Issue Bioaerosol Sensor, version 3 (WIBS3) in the diameter range 0.8 μm≤DP≤20 μm for 2–3 weeks and filters were analysed using energy dispersive X-ray (EDX) spectroscopy, which revealed mostly non-PBA dominated particle sizes larger than 1 μm in Manchester. The WIBS3 features three fluorescence channels: Fluorescence excited at 280 nm is recorded at 310–400 nm and 400–600 nm and fluorescence excited at 370 nm is detected at 400–600 nm. In Manchester the primary size mode of fluorescent and non-fluorescent material was at 1.2 μm. In Borneo non-fluorescent material peaked at 1.2 μm and fluorescent at 3–4 μm. The fluorescence intensity at 400–600 nm generally increased with DP at both sites, as did the 310–400 nm intensity in Borneo. In Manchester the 310–400 m fluorescence decreased at DP>4 μm, suggesting this channel offers additional discrimination between fluorescent particle types. Finally, the ratio of fluorescence intensity in two pairs of channels was investigated as a function of particle diameter and this varied significantly between the two environments, demonstrating that the fluorescent aerosol in each can in principle be distinguished using a combination of fluorescence and elastic scattering measurements.

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Zinin, Pavel V., Alexander V. Pavlov, Artyom S. Galkin et Andrey L. Golovin. « Studying of Degradation of Fluorescent Properties of Graphite-Like Carbon Nitride ». Light & ; Engineering, n^o 06-2022 (décembre 2022) : 69–78. http://dx.doi.org/10.33383/2022-049.

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Graphite-like carbon nitride is a two-dimensional fluorescent material with discovered degradation of fluorescent properties. It was obtained by thermal decomposition of melamine and was studied using IR spectroscopy, transmission electron microscopy, and X-ray phase analysis. Three major fluorescence degradation mechanisms were identified. The first and the third ones are based on hydrogen addition to centres with an unshared electron pair, which leads to alteration of fluorescent properties and the second one is adsorption of water, which accumulates not only on the surface of the material but also probably permeates between the layers, thus leading to insignificant decrease of fluorescence.

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Zhang, Li, Jia-Qing Chen, Ming-Fang Hong, Ru-Ping Liang et Jian-Ding Qiu. « Facile synthesis of fluorescent tungsten oxide quantum dots for telomerase detection based on the inner filter effect ». Analyst 145, n^o 7 (2020) : 2570–79. http://dx.doi.org/10.1039/d0an00296h.

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A facile method has been proposed for the fabrication of fluorescent tungsten oxide quantum dots (WO_x QDs) that have been employed for telomerase sensing based on the fluorescence changes in the inner filter effect between WO_x QDs and hemin.

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Bedo, D. G. « Fluorescence banding in mitotic and meiotic chromosomes of the Mediterranean fruit fly, Ceratitis capitata (Diptera : Tephritidae) ». Genome 32, n^o 4 (1 août 1989) : 580–88. http://dx.doi.org/10.1139/g89-485.

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Mitotic and meiotic chromosomes of the Mediterranean fruit fly, Ceratitis capitata, were studied using three counterstain-enhanced fluorescence staining methods. The tristaining technique allowed chromomycin A3 (CMA) and distamycin – diamidinophenylindole (DA–DAPI) fluorescence to be observed on the same chromosomes. DAPI–actinomycin D (DAPI–AMD) fluorescence was also carried out. These techniques were complemented with quinacrine staining and C-banding. The results were compared with earlier data on silver staining. The sex chromosomes, particularly the X chromosome, show great banding detail with extensive longitudinal differentiation in mitotic chromosomes. GC- and AT-specific fluorescence is not found in the expected reciprocal pattern at all sites. Comparison with C-banding and silver staining shows that intense fluorescence occurs in lightly C banded regions and silver bands correspond to fluorescent bands rather than nucleolar organizers. The combination of staining data suggests that much of the X chromosome has characteristics intermediate between heterochromatin and euchromatin. Meiotic X chromosomes show much less detail and reduced fluorescence intensity but can still be easily traced throughout meiosis and spermatogenesis.Key words: fluorescence banding, sex chromosomes, Mediterranean fruit fly, Ceratitis capitata.

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Royant, Antoine, Philippe Carpentier, Jérémy Ohana, John McGeehan, Bernhard Paetzold, Marjolaine Noirclerc-Savoye, Xavier Vernède, Virgile Adam et Dominique Bourgeois. « Advances in spectroscopic methods for biological crystals. 1. Fluorescence lifetime measurements ». Journal of Applied Crystallography 40, n^o 6 (10 novembre 2007) : 1105–12. http://dx.doi.org/10.1107/s0021889807044196.

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Synchrotrons are now producing thousands of macromolecular structures each year. The need for complementary techniques available on site has progressively emerged, either to assess the relevance of the structure of a protein or to monitor changes that may occur during X-ray diffraction data collection. Microspectrophotometers in the UV–visible absorbance or fluorescence mode have evolved over the past few decades to become the instruments of choice to perform such tests. Described here are recent improvements to the microspectrophotometer of the so-called Cryobench laboratory located at the European Synchrotron Radiation Facility, Grenoble, France. Optical and mechanical properties have been enhanced so as to record better spectra on smaller samples. A device has been implemented to measure the signal decay of fluorescent samples, either in the crystalline or in the solution state. Recording of the fluorescence lifetime in addition to the steady-state fluorescence emission spectrum allows precise monitoring of the fluorescent sample under study. The device consists of an adaptation of a commercially available time-correlated single-photon-counting (TCSPC) system. A method to record and analyze series of TCSPC histograms,e.g.collected as a function of temperature, is described. To validate the instruments, fluorescence lifetimes of fluorescent small molecules or proteins in the crystalline or solution state, at room and cryo temperatures, have been measured. Lifetimes of a number of fluorescent proteins of the GFP family were generally found to be shorter in crystals than in solution, and slightly longer at cryo temperatures than at ambient temperature. The possibility of performing fluorescence lifetime measurements on crystals at synchrotron facilities widens the variety of spectroscopic techniques complementing X-ray diffraction on macromolecular crystallography beamlines.

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Fan, Xiaozhou, Wenqi Zhang, Fangcheng Lü, Yueyi Sui, Jiaxue Wang et Ziqiang Xu. « Research of Fluorescent Properties of a New Type of Phosphor with Mn2+-Doped Ca2SiO4 ». Sensors 21, n^o 8 (15 avril 2021) : 2788. http://dx.doi.org/10.3390/s21082788.

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Fluorescent optical fiber temperature sensors have attracted extensive attention due to their strong anti-electromagnetic interference ability, good high-voltage insulation performance, and fast response speed. The fluorescent material of the sensor probe directly determines the temperature measurement effect. In this paper, a new type of fluorescent material with a Mn2+-doped Ca2SiO4 phosphor (CSO:Mn2+) is synthesized via the solid-state reaction method at 1450 °C. The X-ray diffraction spectrum shows that the sintered sample has a pure phase structure, although the diffraction peaks show a slight shift when dopants are added. The temperature dependence of the fluorescence intensity and lifetime in the range from 290 to 450 K is explored with the help of a fluorescence spectrometer. Green emission bands peaking at 475 and 550 nm from Mn2+ are observed in the fluorescence spectra, and the intensity of emitted light decreases as the temperature rises. The average lifetime of CSO:Mn2+ is 17 ms, which is much higher than the commonly used fluorescent materials on the market. The fluorescence lifetime decreases with increasing temperature and shows a good linear relationship within a certain temperature range. The research results are of great significance to the development of a new generation of fluorescence sensors.

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Levi, V., Q. Ruan, K. Kis-Petikova et E. Gratton. « Scanning FCS, a novel method for three-dimensional particle tracking ». Biochemical Society Transactions 31, n^o 5 (1 octobre 2003) : 997–1000. http://dx.doi.org/10.1042/bst0310997.

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We describe a novel method to track fluorescent particles in three dimensions with nanometre precision and millisecond time resolution. In this method, we use our two-photon excitation microscope. The galvomotor-driven x–y scanning mirrors allow the laser beam to move repetitively in a circular path with a radius of half the width of the point spread function of the laser. When the fluorescent particle is located within the scanning radius of the laser, the precise position of the particle in the x–x plane can be determined by its fluorescence intensity distribution along the circular scanning path. A z-nanopositioner on the objective was used to change the laser focus at two planes (half width of the point spread function apart). The difference of the fluorescence intensity in the two planes is used to calculate the z-position of the fluorescent particle. The laser beam is allowed to scan multiple circular orbits before it is moved to the other plane, thus improving the signal to noise ratio. With a fast feedback mechanism, the position of the laser beam is directed to the centre of the fluorescent particle, thus allowing us to track a particle in three dimensions. In this contribution we describe some calibration experiments performed to test the three-dimensional tracking capability of our system over a large range.

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Shugar, Aaron, Krista Lough et Jiuan Jiuan Chen. « Characterization of a Surface Tarnish Found on Daguerreotypes Revealed under Shortwave Ultraviolet Radiation ». MRS Proceedings 1656 (18 juillet 2014) : 319–33. http://dx.doi.org/10.1557/opl.2014.706.

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ABSTRACTA characteristic fluorescent tarnish can be observed on some daguerreotypes under shortwave ultraviolet radiation. The fluorescence can be seen in several distinct patterns: edge tarnish, rings, and continuous films. Dispersive Raman spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) were applied to characterize and identify the fluorescent compound. Raman spectroscopy identified the characteristic peak for copper cyanide, CuCN, at 2172 cm-1. Elemental k-ratio maps of the SEM analysis indicated an increase in copper, sodium, carbon and nitrogen in the area of fluorescence. XRD confirmed the identification of a copper cyanide compound. Shortwave ultraviolet radiation can be used in a monitoring program of daguerreotypes to further characterize the fluorescent tarnish and its effect on the deterioration of daguerreotypes.

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Kaneyoshi, T., T. Ishihara, H. Yoshioka, M. Motoyama, S. Fukushima, K. Hayashi, J. Kawai, K. Taniguchi, S. Hayakawa et Y. Gohshi. « Material analysis end-station of the Hyogo-ken beamline at SPring-8 ». Journal of Synchrotron Radiation 5, n^o 3 (1 mai 1998) : 509–11. http://dx.doi.org/10.1107/s0909049598001502.

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Plans to construct surface-analysis equipment which will be placed on beamline BL24XU of SPring-8 are presented. There are three experimental hutches in BL24XU, which are available simultaneously by using diamond monochromators as beam splitters. The purpose of the surface-analysis equipment is the simultaneous measurement of fluorescent and diffracted X-rays in grazing-incidence geometry. The instrument is equipped with a solid-state detector (SSD) and a flat position-sensitive proportional counter (PSPC) combined with analysing crystals for X-ray fluorescence (XRF) analysis. A curved PSPC and the goniometer that mounts the SSD used for XRF are also installed for X-ray diffraction. X-ray fluorescence holography and polarized X-ray emission spectroscopy modes are available, so three-dimensional images of atomic configurations and also the anisotropic structure of materials will be studied.

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Meng, Jie, Cheng Sun, Xiao Xiu Hao, Xin Ni Mu et Jian Qing Wang. « Synthesis and Fluorescent Property of Europium-Doped Complexes with P-Anisic Acid and Thenoyltrifluoroacetone ». Advanced Materials Research 380 (novembre 2011) : 125–28. http://dx.doi.org/10.4028/www.scientific.net/amr.380.125.

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Quaternary europium complex EuxGd(1-x)(POA)(TTA)2Phen were synthesized by doping no-fluorescent inert ions Gd3+with ligands of POA, α-thenoyltrifluoroacetone (TTA), and o-phenanthroline(Phen).IR spectra was studied , indicate that these complexes have similar structures, have bonded with the ligands.The fluorescent properties,the influence of fluorescent property by doping ions Gd3+were studied. The results showed that the doping ions Gd3+can enhance the fluorescence intensities, the best mole ratio of europium to gadolinium is 6：4.

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Golub, Maksym, Virginia Guillon, Guillaume Gotthard, Dominik Zeller, Nicolas Martinez, Tilo Seydel, Michael M. Koza et al. « Dynamics of a family of cyan fluorescent proteins probed by incoherent neutron scattering ». Journal of The Royal Society Interface 16, n^o 152 (mars 2019) : 20180848. http://dx.doi.org/10.1098/rsif.2018.0848.

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Cyan fluorescent proteins (CFPs) are variants of green fluorescent proteins in which the central tyrosine of the chromophore has been replaced by a tryptophan. The increased bulk of the chromophore within a compact protein and the change in the positioning of atoms capable of hydrogen bonding have made it difficult to optimize their fluorescence properties, which took approximately 15 years between the availability of the first useable CFP, enhanced cyan fluorescent protein (ECFP), and that of a variant with almost perfect fluorescence efficiency, mTurquoise2. To understand the molecular bases of the progressive improvement in between these two CFPs, we have studied by incoherent neutron scattering the dynamics of five different variants exhibiting progressively increased fluorescence efficiency along the evolution pathway. Our results correlate well with the analysis of the previously determined X-ray crystallographic structures, which show an increase in flexibility between ECFP and the second variant, Cerulean, which is then hindered in the three later variants, SCFP3A (Super Cyan Fluorescent Protein 3A), mTurquoise and mTurquoise2. This confirms that increasing the rigidity of the direct environment of the fluorescent chromophore is not the sole parameter leading to brighter fluorescent proteins and that increased flexibility in some cases may be helpful.

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Horakeri, L. D., S. G. Bubbly et S. B. Gudennavar. « K-Shell Fluorescence Yield of Thorium Present in its Compound ». Mapana - Journal of Sciences 8, n^o 2 (30 novembre 2009) : 54–58. http://dx.doi.org/10.12723/mjs.15.6.

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A simple method, proposed by us earlier, - 2π geometrical configuration coupled with the thickness criterion - to measure the Kshell X-ray fluorescence parameters is extended to high Z material- Thorium. The fluorescent X-rays are generated by a weak Co-57 radioactive source and detected by employing a NaI (Tl) detector spectrometer. Measured value is compared with the best fitted value produced by Hubbell et al. and with the experimental value of Balakrishna et al. We found good agreement with each other, thus establishing the applicability of our simple method for measuring fluorescence yield of high Z element.

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Yan, Xiangyu, Bowen Jiang, Cheng Chen, Ye Yuan, Guanggao Fan, Yu Zou et Wei Sang. « Bridging Chlorine Atoms Enable the Construction of a Novel Benzimidazole-Derived Fluorescent Molecule ». Synlett 33, n^o 07 (7 mars 2022) : 684–88. http://dx.doi.org/10.1055/a-1790-2858.

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AbstractWe have designed and prepared a novel benzimidazole-based fluorescent molecule through the construction of chlorine bridges. The structure of the molecule was authenticated by means of X-ray crystallography and its photophysical properties (absorption and fluorescence spectra) were investigated. Furthermore, the fluorescence emission of the molecule was rationalized through density functional theory calculations, which showed the influence of the bridging chlorine atoms on the energy levels and energy gap.

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Wang, Ning, Xuan Wang, Junjie Lv, Peng Yang, Weihua Jia, Wei Bian et Martin M. F. Choi. « A fluorescent probe using phosphorus-doped graphite carbon nitride nanosheets for the detection of silver ions and cell imaging ». Canadian Journal of Chemistry 98, n^o 8 (août 2020) : 408–14. http://dx.doi.org/10.1139/cjc-2019-0353.

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The fluorescent phosphorus-doped graphite carbon nitride (P-g-C3N4) nanosheets have been synthesized as a fluorescence probe using an ultrasonic exfoliating method. The as-prepared P-g-C3N4 nanosheets were characterized by multiple analytical techniques such as transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and infrared spectroscopy. The fluorescence intensity of P-g-C3N4 nanosheets decreases with the increase in concentration of silver ions. A good linear relationship was achieved between the corresponding fluorescence intensity of P-g-C3N4 nanosheets and the concentration of silver ions in the range of 20 nmol/L – 3.2 μmol/L. The quenching mechanism of interaction between P-g-C3N4 nanosheets and silver ions was primarily discussed. The proposed fluorescence probe has been successfully applied to detect silver ions in real water samples and the recoveries range from 96.8% to 103.7%.

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Alkhursani, Sheikha A., Mohamed Mohamady Ghobashy et Mohamed Madani. « Radiation Synthesis of Organostarch as Fluorescence Label ». Asian Journal of Chemistry 32, n^o 7 (2020) : 1799–805. http://dx.doi.org/10.14233/ajchem.2020.22593.

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Fluorescence label preparation, being the core of sensing and imaging, is the most interesting aspect of label technology. Using the gamma irradiation technique, a facial method is proposed to prepare organostarch consisting of polyaniline and starch. Polyaniline was introduced into starch molecules to form an inclusion complex between V-type starch and aniline monomer. The inclusion complex thus formed consisted of starch-aniline crosslink caused by gamma irradiation through organostarch crosslinks. Thus, organostarch develops fluorescence property at 470 nm possibly through the interaction of aniline and starch, which are both fluorophores. A comparative analysis of variations is performed in common fluorescent labels of starch and organostarch based on their physico-chemical properties. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectrometry were utilized to confirm the inclusion of polyaniline into starch molecules. Furthermore, using a fluorescence microscope, the positive implementation of fluorescent organostarch was verified. Fluorescent organostarch can be synthesized through this simple method and can be widely used for developing biomarkers and biosensors in food and biomedical industries. Organostarch produces florescence under mild conditions even without complicated preparations, such as additives for labelling with dye fluorescence. The intensity of fluorescence of organostarch was 17,000 times that of natural starch.

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Markwardt, Michele L., Gert-Jan Kremers, Catherine A. Kraft, Krishanu Ray, Paula J. C. Cranfill, Korey A. Wilson, Richard N. Day, Rebekka M. Wachter, Michael W. Davidson et Megan A. Rizzo. « An Improved Cerulean Fluorescent Protein with Enhanced Brightness and Reduced Reversible Photoswitching ». PLoS ONE 6, n^o 3 (29 mars 2011) : e17896. http://dx.doi.org/10.1371/journal.pone.0017896.

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Cyan fluorescent proteins (CFPs), such as Cerulean, are widely used as donor fluorophores in Förster resonance energy transfer (FRET) experiments. Nonetheless, the most widely used variants suffer from drawbacks that include low quantum yields and unstable flurorescence. To improve the fluorescence properties of Cerulean, we used the X-ray structure to rationally target specific amino acids for optimization by site-directed mutagenesis. Optimization of residues in strands 7 and 8 of the β-barrel improved the quantum yield of Cerulean from 0.48 to 0.60. Further optimization by incorporating the wild-type T65S mutation in the chromophore improved the quantum yield to 0.87. This variant, mCerulean3, is 20% brighter and shows greatly reduced fluorescence photoswitching behavior compared to the recently described mTurquoise fluorescent protein in vitro and in living cells. The fluorescence lifetime of mCerulean3 also fits to a single exponential time constant, making mCerulean3 a suitable choice for fluorescence lifetime microscopy experiments. Furthermore, inclusion of mCerulean3 in a fusion protein with mVenus produced FRET ratios with less variance than mTurquoise-containing fusions in living cells. Thus, mCerulean3 is a bright, photostable cyan fluorescent protein which possesses several characteristics that are highly desirable for FRET experiments.

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Trachman, Robert J., Jason R. Stagno, Chelsie Conrad, Christopher P. Jones, Pontus Fischer, Alke Meents, Yun-Xing Wang et Adrian R. Ferré-D'Amaré. « Co-crystal structure of the iMango-III fluorescent RNA aptamer using an X-ray free-electron laser ». Acta Crystallographica Section F Structural Biology Communications 75, n^o 8 (1 août 2019) : 547–51. http://dx.doi.org/10.1107/s2053230x19010136.

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Turn-on aptamers are in vitro-selected RNAs that bind to conditionally fluorescent small molecules and enhance their fluorescence. Upon binding TO1-biotin, the iMango-III aptamer achieves the largest fluorescence enhancement reported for turn-on aptamers (over 5000-fold). This aptamer was generated by structure-guided engineering and functional reselection of the parental aptamer Mango-III. Structures of both Mango-III and iMango-III have previously been determined by conventional cryocrystallography using synchrotron X-radiation. Using an X-ray free-electron laser (XFEL), the room-temperature iMango-III–TO1-biotin co-crystal structure has now been determined at 3.0 Å resolution. This structural model, which was refined against a data set of ∼1300 diffraction images (each from a single crystal), is largely consistent with the structures determined from single-crystal data sets collected at 100 K. This constitutes a technical benchmark on the way to XFEL pump–probe experiments on fluorescent RNA–small molecule complexes.

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Klovak, Viktoriia, Sergey Kulichenko et Serhii Lelyushok. « Matching Effects in the Interaction of Ionic Surfactants with Fluorescent Reagents in Micellar Solutions of Triton X-100 ». Methods and Objects of Chemical Analysis 16, n^o 3 (2021) : 117–26. http://dx.doi.org/10.17721/moca.2021.117-126.

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The influence of cationic and anionic surfactant solutions on the character of the fluorescence spectra of reagents of different charge and hydrophobicity in aqueous solutions of nonionic surfactant Triton X-100 has been studied. An increase in the fluorescence intensity and a shift in the position of the fluorescence maximum with increasing hydrophobicity of reagents and ionic surfactants have been shown. The analytical signal of the surfactant is further amplified in the proximity of the charge values of the reagent and the counterion of the surfactant. The non-monotonic nature of the hydrophobicity effect of cationic surfactants on their analytical signal in the system has been shown. The observed effects are explained by the realization of charge and hydrophobic matching in the interaction of surfactants with the fluorescent reagents. The obtained effects are significant in the design of fluorescent systems for the determination and study of surfactant micelles. Conditions for detecting the content of cetylpyridinium chloride by reaction with eosin Y and sodium tetradecyl sulfate by reaction with rhodamine 6G in the presence of Triton X-100 were proposed. The methods have been tested in detecting the content of the ionic surfactants in pharmaceuticals.

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Balu, Rajkamal, Robert Knott, Christopher M. Elvin, Anita J. Hill, Namita R. Choudhury et Naba K. Dutta. « A Sustainable Biomineralization Approach for the Synthesis of Highly Fluorescent Ultra-Small Pt Nanoclusters ». Biosensors 9, n^o 4 (29 octobre 2019) : 128. http://dx.doi.org/10.3390/bios9040128.

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Herein we report the first example of a facile biomineralization process to produce ultra-small-sized highly fluorescent aqueous dispersions of platinum noble metal quantum clusters (Pt-NMQCs) using a multi-stimulus responsive, biomimetic intrinsically disordered protein (IDP), Rec1-resilin. We demonstrate that Rec1-resilin acts concurrently as the host, reducing agent, and stabilizer of the blue-green fluorescent Pt-NMQCs once they are being formed. The photophysical properties, quantum yield, and fluorescence lifetime measurements of the synthesized Pt-NMQCs were examined using UV-Vis and fluorescence spectroscopy. The oxidation state of the Pt-NMQCs was quantitatively analyzed using X-ray photoelectron spectroscopy. Both a small angle X-ray scattering technique and a modeling approach have been attempted to present a detailed understanding of the structure and conformational dynamics of Rec1-resilin as an IDP during the formation of the Pt-NMQCs. It has been demonstrated that the green fluorescent Pt-NMQCs exhibit a high quantum yield of ~7.0% and a lifetime of ~9.5 ns in aqueous media. The change in photoluminescence properties due to the inter-dot interactions between proximal dots and aggregation of the Pt-NMQCs by evaporation was also measured spectroscopically and discussed.

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Li, Xin, Xiaoling Wang, Wei Guo, Yunfei Wang, Qing Hua, Feiyan Tang, Feng Luan, Chunyuan Tian, Xuming Zhuang et Lijun Zhao. « Selective Detection of Alkaline Phosphatase Activity in Environmental Water Samples by Copper Nanoclusters Doped Lanthanide Coordination Polymer Nanocomposites as the Ratiometric Fluorescent Probe ». Biosensors 12, n^o 6 (28 mai 2022) : 372. http://dx.doi.org/10.3390/bios12060372.

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In this paper, a novel, accurate, sensitive and rapid ratiometric fluorescent sensor was fabricated using a copper nanoclusters@infinite coordination polymer (ICP), specifically, terbium ion-guanosine 5’-disodium (Cu NCs@Tb-GMP) nanocomposites as the ratiometric fluorescent probe, to detect alkaline phosphatase (ALP) in water. The fluorescence probe was characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The experimental results showed that, compared with Tb-GMP fluorescent sensors, Cu ratiometric fluorescent sensors based on NCs encapsulated in Tb-GMP had fewer experimental errors and fewer false-positive signals and were more conducive to the sensitive and accurate detection of ALP. In addition, the developed fluorescent probe had good fluorescence intensity, selectivity, repeatability and stability. Under optimized conditions, the ratiometric fluorescent sensor detected ALP in the range of 0.002–2 U mL−1 (R2 = 0.9950) with a limit of detection of 0.002 U mL−1, and the recovery of ALP from water samples was less than 108.2%. These satisfying results proved that the ratiometric fluorescent probe has good application prospects and provides a new method for the detection of ALP in real water samples.

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dos Santos, J. M. F., et Benilde E. O. Costa. « Window Area Effects in the Detector Efficiency for Source Excited EDXRF Geometries ». Advances in X-ray Analysis 31 (1987) : 455–59. http://dx.doi.org/10.1154/s0376030800022308.

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AbstractThe efficiency dependence on detector window area for three different geometries of source excited energy dispersive X-ray fluorescence (EDXRF) analysis systems are calculated using the Monte Carlo method. Two typical samples (coal and oil) are considered for discussion. The results show that the efficiency is affected mainly by geometric factors: source-to-sample distance and absorption of the exciting X-rays; fluorescent photon self-absorption has a much smaller effect.

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Simionovici, A., B. Golosio, A. Somogyi et L. Lemelle. « F13 Application of Fluorescent Microtomography and Other X-ray Fluorescence Techniques - Invited ». Powder Diffraction 18, n^o 2 (juin 2003) : 174. http://dx.doi.org/10.1154/1.1706950.

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Gabriëls, R. Y., M. Linssen, A. van der Waaij, P. Volkmer, W. Hooghiemstra, G. Kats-Ugurlu, D. Robinson, G. Dijkstra et W. Nagengast. « DOP15 Fluorescent labelled vedolizumab for real-time visualization and quantification of local drug distribution and pharmacodynamics in Inflammatory Bowel Diseases during endoscopy ». Journal of Crohn's and Colitis 16, Supplement_1 (1 janvier 2022) : i064—i065. http://dx.doi.org/10.1093/ecco-jcc/jjab232.054.

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Abstract Background Vedolizumab is a monoclonal antibody which blocks integrin α4β7 inhibiting trafficking of T-lymphocytes into the gut. Unfortunately, up to 60% of vedolizumab patients experience non-response. The mechanism of action of vedolizumab is not elucidated, predictors of response are unknown and data for local drug distribution in the gut are lacking. In this clinical trial, we investigated the feasibility of assessing local distribution of fluorescently labelled vedolizumab in the gut mucosa of inflammatory bowel diseases (IBD) patients to finally enable prediction of therapy response in individual patients. Methods Vedolizumab (Entyvio, Takeda Pharma) was labelled to IRDye 800CW under cGMP conditions to yield clinical grade vedolizumab-800CW. In this dose-escalation trial, vedolizumab naïve IBD patients and IBD patients treated with vedolizumab for at least 14 weeks were included. Patients received an intravenous dose of fluorescently labelled vedolizumab of either 0 mg, 4.5 mg, 15 mg or 15 mg + 75 mg unlabelled vedolizumab 3 days prior colonoscopy. In vivo fluorescence imaging was assessed by fibre-based wide-field fluorescence molecular endoscopy (FME) and quantified by spectroscopy in healthy, mildly inflamed and severely inflamed tissue. All assessed tissue was biopsied for ex vivo examination of the fluorescent signal, fluorescence microscopy and spectroscopy. Results Up to submission 34 patients completed tracer injection and FME. An interim analysis was performed after 20 patients (5 in each dose group), which showed in severely inflamed tissue an 8 fold higher fluorescent signal in the 15 mg dose group (0.049 Q*μfa,x [mm-1]) compared to the control group (0.006 μfa,x [mm-1]) (p<0.05). Furthermore, the fluorescent signal within the 15 mg dose group was also 2.5 fold higher compared to healthy tissue (0.019 Q*μfa,x [mm-1]) (p<0.05).The addition of unlabelled vedolizumab gave similar results to the 15 mg group (p>0.99), suggesting that the drug target was still not saturated. The optimal dosage group of 15 mg was expanded up to 18 IBD patients, amongst them 6 IBD patients after 14 weeks of treatment regimen. Fluorescence microscopy showed clustering of fluorescent signals especially in inflamed mucosa. Additional experiments to detect vedolizumab target cells are ongoing. Conclusion In vivo visualization of fluorescent vedolizumab revealed a clear dose-dependent correlation between mucosal drug concentrations and the severity of mucosal inflammation. Fluorescence molecular endoscopy is a promising novel tool to get insight in drug distribution in IBD, detect target cells, assess target engagement and possibly predict therapy response in individual patients.

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Mori, H., S. Haruyama, Y. Shinozaki, H. Okino, A. Iida, R. Takanashi, I. Sakuma, W. K. Husseini, B. D. Payne et J. I. Hoffman. « New nonradioactive microspheres and more sensitive X-ray fluorescence to measure regional blood flow ». American Journal of Physiology-Heart and Circulatory Physiology 263, n^o 6 (1 décembre 1992) : H1946—H1957. http://dx.doi.org/10.1152/ajpheart.1992.263.6.h1946.

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We developed new nonradioactive microspheres and used more sensitive X-ray fluorescence spectrometers than used previously to measure regional blood flow in the heart and other organs. We demonstrated the chemical stability of eight kinds of heavy element-loaded microspheres and validated their use for regional blood flow measurement by comparing duplicate flows measured with radioactive and/or nonradioactive microspheres in both acute and chronic dog experiments. The wavelength-dispersive spectrometer (Philips PW 1480) has a higher sensitivity than the previously described X-ray fluorescent system and reduced the number of microspheres required for accurate measurement. The fine energy resolution of this system makes it possible to increase the numbers of different kinds of microspheres to be quantitated, but at present only eight kinds are available. We also used a synchrotron radiation-excited energy dispersive spectrometer. The monochromatic synchrotron radiation allowed us to obtain much higher signal-to-background ratios of X-ray fluorescence spectra than with the wavelength-dispersive system (50 dB more for Zr-loaded microspheres) and will enable analysis of fluorescent activity in smaller regions (< 20 mg) than the radioactive method does.

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Jeon, Jae-Kun, et Jong-Ki Kim. « Track analysis of a synchrotron X-ray photoelectric nanoradiator by in situ fluorescence imaging of reactive oxygen species : comparative study of gold and iron oxide nanoparticles ». Journal of Synchrotron Radiation 25, n^o 6 (20 septembre 2018) : 1768–73. http://dx.doi.org/10.1107/s1600577518011396.

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The emission of fluorescent X-rays and low-energy electrons by mid-/high-Z nanoparticles upon irradiation with either X-ray photons or high-energy ion beams is referred to as the nanoradiator effect (NRE). A track analysis of NRE was performed using reactive oxygen species (ROS) gels, to which macrophages containing gold nanoparticles (AuNPs) were attached, together with single-cell irradiation of the intracellular nanoparticles from a microbeam of synchrotron X-rays, and the range and distribution of ^\bulletOH and O2^{ \bullet - } produced were compared with those of the Fe-nanoradiator by magnetite nanoparticles (FeONP, Fe3O4). The Au-nanoradiator generated ROS fluorescence to a greater depth and wider angle with respect to the incident X-rays than that of the Fe-nanoradiator. The ROS-oxidant fluorescence intensity ratios of ^\bulletOH to O2^{ \bullet - } were different for the AuNPs and FeONPs, reflecting different relative yields of electrons and fluorescent X-rays from NRE. In the region immediately (<100 µm) below the irradiated cell, ^\bulletOH-radicals were distributed mainly along two or three tracks in the depth direction in the FeONP- or AuNP-ROS gel. In contrast, O2^{ \bullet - } was scattered more abundantly in random directions in the AuNP-ROS gel than in the FeONP-ROS gel. Track analysis of X-ray photoelectric nanoradiator radiation showed a different range of dose distribution and relative emission compositions between Au- and Fe-nanoradiators, suggesting more extensive damage beyond a single cell containing AuNPs than one containing FeONPs.

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Jayaraman, Jayabharathi, et Jayamoorthy Karunamoorthy. « Sensing Nanoparticulate ZnO with Benzimidazole Derivative by Fluorescence ». Key Engineering Materials 543 (mars 2013) : 63–67. http://dx.doi.org/10.4028/www.scientific.net/kem.543.63.

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A sensitive benzimidazole derivative fluorescent sensor for nanoparticulate ZnO has been designed and synthesized. The nanocrystalline ZnO, Ag doped ZnO and Cu doped ZnO have been synthesised by sol-gel method and characterized by powder X-ray diffraction, scanning electron microscopy (SEM) and UV-visible diffuse reflectance, photoluminescence and electrochemical impedance spectroscopies. The synthesized sensor emits fluorescence at 360 nm and this fluorescence is selectively enhanced by nanocrystalline ZnO. This technique is sensitive to detect and estimate ZnO at micro molar level. Impurities such as Ag and Cu do not hamper the sensitivity of this technique significantly. Keywords: Sensor, SEM, EDX, Impedance, Fluorescence

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Wang, Hui, Xiaohe Tian, Wei Du, Qiong Zhang, Lijuan Guan, Aidong Wang, Yujin Zhang et al. « A two-photon fluorescent RNA probe screened from a series of oxime-functionalized 2,2′:6′,2′′-terpyridine ZnX2(X = Cl, Br, I) complexes ». Journal of Materials Chemistry B 4, n^o 28 (2016) : 4818–25. http://dx.doi.org/10.1039/c6tb01202g.

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Maddu, Akhiruddin, Sejahtera Ahmad et Tony Sumaryada. « Development of Glucose Meter Using Boric Acid-Modified Carbon Dots as Fluorescent Probe ». Photonics Letters of Poland 13, n^o 3 (30 septembre 2021) : 49. http://dx.doi.org/10.4302/plp.v13i3.1080.

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A glucose meter has been developed utilizing boric acid-modified carbon dots as a fluorescence probe. Boric acid-modified carbon dots produces varying fluorescence emission with varying glucose concentration in water. Boric acid-modified carbon dots mixed with glucose addition was excited by a violet laser (405 nm), then the emission intensity was detected by a photodetector to be converted to an electrical signal that as an input signal for a microcontroller for glucose concentration measurement. The output voltage of the glucose meter is corresponding to the fluorescence emission measured by using a spectrofluorometer with glucose concentration in the boric acid-modified carbon dots. Full Text: PDF ReferencesH. Teymourian, A. Barfidokht, J. Wang, "Electrochemical glucose sensors in diabetes management: an updated review (2010–2020)", Chem. Soc. Rev. 49, 7671 (2020). CrossRef D.C. Klonoff, "Overview of Fluorescence Glucose Sensing: A Technology with a Bright Future", J Diabetes Sci. Technol. 6(6), 1242 (2012). CrossRef J.C. Pickup, F. Hussain, N.D. Evans, O.J. Rolinski, David J.S. Birch, "Fluorescence-based glucose sensors", Biosens. Bioelectron. 20, 2555 (2005). CrossRef H. Fang, G. Kaur, B. Wang, "Progress in Boronic Acid-Based Fluorescent Glucose Sensors", J. Fluoresc. 14(5), 481 (2004). CrossRef T. Kawanishi, M.A. Romey, P.C. Zhu, M.Z. Holody, S. Shinkai, "A Study of Boronic Acid Based Fluorescent Glucose Sensors", J. Fluoresc. 14(5), 499 (2004). CrossRef A.S. Krishna, P.A. Nair, C. Radhakumary, K. Sreenivasan, "Carbon dot based non enzymatic approach for the detection and estimation of glucose in blood serum", Mater. Res. Express 3(1), 055001 (2016). CrossRef G.P.C. Mello, E.F.C. Simões, D.M.A. Crista, J.M.M. Leitão, L. Pinto da Silva, J.C.G. Esteves da Silva, "Glucose Sensing by Fluorescent Nanomaterials", Crit. Rev. Anal. Chem. 49(6), 542 (2019). CrossRef X. Shan, L. Chai, J. Ma, Z. Qian, J. Chen, H. Feng, "B-doped carbon quantum dots as a sensitive fluorescence probe for hydrogen peroxide and glucose detection", Analyst 139, 2322 (2014). CrossRef J. Dong, S. Li, H. Wang, Q. Meng, L. Fan, H. Xie, C. Cao, W. Zhang, "Simple Boric Acid-Based Fluorescent Focusing for Sensing of Glucose and Glycoprotein via Multipath Moving Supramolecular Boundary Electrophoresis Chip", Anal. Chem. 85(12), 5884 (2013). CrossRef Y. Cui, F. Chen, X-B. Yin, "A ratiometric fluorescence platform based on boric-acid-functional Eu-MOF for sensitive detection of H2O2 and glucose", Biosens. Bioelectron. 135, 208 (2019). CrossRef

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Pang, Liaoliao, Jinfa Ming, Fukui Pan et Xin Ning. « Fabrication of Silk Fibroin Fluorescent Nanofibers via Electrospinning ». Polymers 11, n^o 6 (4 juin 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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Gabey, A. M., W. R. Stanley, M. W. Gallagher et P. H. Kaye. « The fluorescence properties of aerosol larger than 0.8 μm in urban and tropical rainforest locations ». Atmospheric Chemistry and Physics 11, n^o 11 (15 juin 2011) : 5491–504. http://dx.doi.org/10.5194/acp-11-5491-2011.

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Abstract. UV-LIF measurements were performed on ambient aerosol in Manchester, UK (urban city centre, winter) and Borneo, Malaysia (remote, tropical) using a Wide Issue Bioaerosol Spectrometer, version 3 (WIBS3). These sites are taken to represent environments with minor and significant primary biological aerosol (PBA) influences respectively, and the urban dataset describes the fluorescent background aerosol against which PBA must be identified by researchers using LIF. The ensemble aerosol at both sites was characterised over 2–3 weeks by measuring the fluorescence intensity and optical equivalent diameter (DP) of single particles sized 0.8 ≤ DP ≤ 20 μm. Filter samples were also collected for a subset of the Manchester campaign and analysed using energy dispersive X-Ray (EDX) spectroscopy and environmental scanning electron microscopy (ESEM), which revealed mostly non-PBA at D ≤ 1 μm. The WIBS3 features three fluorescence channels: the emission following a 280 nm excitation is recorded at 310–400 nm (channel F1) and 400–600 nm (F2), and fluorescence excited at 350 nm is detected at 400–600 nm (F3). In Manchester the primary size mode of fluorescent and non-fluorescent material was present at 0.8–1.2 μm, with a secondary fluorescent mode at 2–4 μm. In Borneo non-fluorescent material peaked at 0.8–1.2 μm and fluorescent at 3–4 μm. Agreement between fluorescent number concentrations in each channel differed at the two sites, with F1 and F3 reporting similar concentrations in Borneo but F3 outnumbering F1 by a factor of 2–3 across the size spectrum in Manchester. The fluorescence intensity in each channel generally rose with DP at both sites with the exception of F1 intensity in Manchester, which peaked at DP = 4 μm, causing a divergence between F1 and F3 intensity at larger DP. This divergence and the differing fluorescent particle concentrations demonstrate the additional discrimination provided by the F1 channel in Manchester. The relationships between fluorescence intensities in different pairs of channels were also investigated as a function of DP. Differences between these metrics were apparent at each site and provide some distinction between the two datasets. Finally, particle selection criteria based on the Borneo dataset were applied to identify a median concentration of 10 "Borneo-like" fluorescent particles per litre in Manchester.

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Vigers, G. P. A., M. Coué et J. R. McIntosh. « Fluorescent microtubules break up under illumination ». Proceedings, annual meeting, Electron Microscopy Society of America 46 (1988) : 36–37. http://dx.doi.org/10.1017/s0424820100102262.

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The dynamic behavior of microtubules (MTs) in living cells has recently been elucidated by the use of tubulin tagged with a fluorescent molecule and then injected into cultured cells. The dynamics of the labelled tubulin are then followed either by watching the incorporation of the fluorescence immediately after injection, or by monitoring fluorescence redistribution after photobleaching (FRAP).Until recently, the best fluorescent analogue of tubulin appeared to be dichlorotriazinyl-amino-fluorescein tubulin (DTAF-tubulin). We have now made fluorescein, rhodamine and X-rhodamine n-hydroxy-succinimidyl derivatives of tubulin. These analogues all have a higher fluorescence to protein (f-to-p) ratio and better in-vitro assembly characteristics than the DTAF-tubulin previously used. They have been injected into cultured PtKl cells, where they incorporate well into the microtubule cytoskeltons of the cells. However, while characterising the properties of these four analogues we discovered that they all suffer from a major problem: Microtubules formed from them, either in vitro or in vivo, are destroyed as the bound fluorophore becomes photobleached. We have characterised the photolability of the fluorescent microtubules both in vivo, using epifluorescence microscopy, and in vitro with DIC microscopy.

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Chen, Hong Yu, et Li Liu. « Synthesis of Photoluminescent Core–Shell-Structured Carbon dots@silica Nanocomposite Fingermark Powders for Latent Fingermarks Visualization ». Nano 14, n^o 06 (juin 2019) : 1950068. http://dx.doi.org/10.1142/s1793292019500681.

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To obtain solid-state photoluminescent core–shell-structured carbon dots@silica (C-dots@SiO2) nanocomposites, the C-dots were synthesized by microwave irradiation and were dispersed in SiO2through sol–gel technique. Then, the excellent fluorescent property with excitation-independent feature and the core–shell structure of C-dots@SiO2nanocomposites were successfully characterized through the fluorescence spectroscopy, ultraviolet–visible absorption spectroscopy (UV-Vis), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The as-prepared C-dots@SiO2powder was mixed with reduced iron powder and then applied to latent fingermark detection. The latent fingermarks on several surfaces labeled with C-dots@SiO2fingermark powders emitted blue fluorescence under 365[Formula: see text]nm UV light and exhibited high contrast between the background and the ridges. Additionally, the C-dots@SiO2fingermark powder as a fluorescent label for enhancing latent fingermarks demonstrated greater advantages as compared to the conventional fluorescent fingermark powder especially for latent fingermark deposited on porous surfaces.

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Mekuria, Tefera, Devinka Bamunusinghe, Mark Payton et Jeanmarie Verchot-Lubicz. « Phloem Unloading of Potato virus X Movement Proteins Is Regulated by Virus and Host Factors ». Molecular Plant-Microbe Interactions® 21, n^o 8 (août 2008) : 1106–17. http://dx.doi.org/10.1094/mpmi-21-8-1106.

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To determine the requirements for viral proteins exiting the phloem, transgenic plants expressing green fluorescent protein (GFP) fused to the Potato virus X (PVX) triple gene block (TGB)p1 and coat protein (CP) genes were prepared. The fused genes were transgenically expressed from the companion cell (CC)-specific Commelina yellow mottle virus (CoYMV) promoter. Transgenic plants were selected for evidence of GFP fluorescence in CC and sieve elements (SE) and proteins were determined to be phloem mobile based on their ability to translocate across a graft union into nontransgenic scions. Petioles and leaves were analyzed to determine the requirements for phloem unloading of the fluorescence proteins. In petioles, fluorescence spread throughout the photosynthetic vascular cells (chlorenchyma) but did not move into the cortex, indicating a specific barrier to proteins exiting the vasculature. In leaves, fluorescence was mainly restricted to the veins. However, in virus-infected plants or leaves treated with a cocktail of proteasome inhibitors, fluorescence spread into leaf mesophyll cells. These data indicate that PVX contributes factors which enable specific unloading of cognate viral proteins and that proteolysis may play a role in limiting proteins in the phloem and surrounding chlorenchyma.

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Atchudan, Raji, Somasundaram Chandra Kishore, Thomas Nesakumar Jebakumar Immanuel Edison, Suguna Perumal, Rajangam Vinodh, Ashok K. Sundramoorthy, Rajendran Suresh Babu, Muthulakshmi Alagan et Yong Rok Lee. « Highly Fluorescent Carbon Dots as a Potential Fluorescence Probe for Selective Sensing of Ferric Ions in Aqueous Solution ». Chemosensors 9, n^o 11 (25 octobre 2021) : 301. http://dx.doi.org/10.3390/chemosensors9110301.

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This paper’s emphasis is on the development of a fluorescent chemosensor for Fe3+ ions in an aqueous solution, using hydrophilic carbon dots (O-CDs). A simple, cost-effective, and environmentally friendly one-step hydrothermal synthesis method was used to synthesize fluorescent hydrophilic O-CDs from Oxalis corniculata (Family; Oxalidaceae). The graphitic structure and size distribution of the O-CDs was verified by X-ray diffraction, Raman spectroscopy, and high-resolution transmission electron microscopy studies. The resulting O-CDs had a near-spherical shape and an adequate degree of graphitization at the core, with an average diameter of 4.5 nm. X-ray photoelectron and Fourier transform infrared spectroscopy methods revealed the presence of several hydrophilic groups (carbonyl, amine, carboxyl, and hydroxyl, along with nitrogen and oxygen-rich molecules) on the surface of O-CDs. The synthesized hydrophilic O-CDs with excitation wavelength-dependent emission fluorescence characteristics showed a high quantum yield of about 20%. Besides this, the hydrophilic O-CDs exhibited a bright and controllable fluorescence with prolonged stability and photo-stability. These fluorescent hydrophilic O-CDs were used as a nanoprobe for the fluorometric identification of Fe3+ ions in an aqueous solution, with high sensitivity and selectivity. By quenching the blue emission fluorescence of this nanosensor, a highly sensitive Fe3+ ion in the range of 10–50 µM with a minimum detection limit of 0.73 µM was achieved. In addition, the developed nanosensor can be used to sense intracellular Fe3+ ions with high biocompatibility and cellular imaging capacity, and it has a lot of potential in biomedical applications.

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Zebrowska, Jadwiga, et Wladyslaw Michalek. « Chlorophyll fluorescence in two strawberry (Fragaria x ananassa Duch.) cultivars ». Journal of Central European Agriculture 15, n^o 4 (2014) : 12–21. http://dx.doi.org/10.5513/jcea01/15.4.1501.

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BADIEI, ALIREZA, et HASSAN GOLDOOZ. « A SIMPLE METHOD FOR PREPARATION OF FLUORESCENT NANOSTRUCTURE SILICA WITH HEXAGONAL ARRAY ». International Journal of Modern Physics : Conference Series 05 (janvier 2012) : 151–59. http://dx.doi.org/10.1142/s2010194512001961.

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A nanostructure modified silica with good fluorescence properties was prepared by grafting Al 3+ ions on the surface of nanoporous silica and then binding of 8-hydroxyquinoline (8- HQ ) to the grafted Al 3+ ions. The prepared material, denoted as NS - AlQ 2, was characterized by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), nitrogen adsorption–desorption measurements, FT-IR and fluorescence spectra. This compound shows emission spectra approximately in the emission range of AlQ 3 complex. This procedure provides a simple method for grafting fluorescent molecules in the channels of nanoporous silica materials.

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Diblík, Jan, Milan Macek, Maria-Cristina Magli, Roman Krejčí et Luca Gianaroli. « Topology of Chromosomes 18 and X in Human Blastomeres from 3- to 4-Day-old Embryos ». Journal of Histochemistry & ; Cytochemistry 53, n^o 3 (mars 2005) : 273–76. http://dx.doi.org/10.1369/jhc.4b6509.2005.

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The positions of chromosomes 18 and X fluorescence in situ hybridization signals were analyzed in blastomeres generated from human in vitro fertilization 3- to 4-day-old embryos after preimplantation screening of aneuploidy of chromosomes 13, 16, 18, 21, 22, X, and Y. Fluorescent signal localization compared with a three-dimensional sphere model of random signal distribution revealed significant differences, providing evidence of peripheral localization of chromosome 18 in aneuploid ( p=0.0013) and aneuploid/euploid blastomeres ( p=0.0011). No differences were found in localization of chromosome 18 in euploid and in chromosome X in euploid and aneuploid blastomeres.

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Crawford, Andrew M., Ben Huntsman, Monica Y. Weng, Olena Ponomarenko, Cheyenne D. Kiani, Simon J. George, Graham N. George et Ingrid J. Pickering. « Abridged spectral matrix inversion : parametric fitting of X-ray fluorescence spectra following integrative data reduction ». Journal of Synchrotron Radiation 28, n^o 6 (29 octobre 2021) : 1881–90. http://dx.doi.org/10.1107/s1600577521008419.

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Recent improvements in both X-ray detectors and readout speeds have led to a substantial increase in the volume of X-ray fluorescence data being produced at synchrotron facilities. This in turn results in increased challenges associated with processing and fitting such data, both temporally and computationally. Herein an abridging approach is described that both reduces and partially integrates X-ray fluorescence (XRF) data sets to obtain a fivefold total improvement in processing time with negligible decrease in quality of fitting. The approach is demonstrated using linear least-squares matrix inversion on XRF data with strongly overlapping fluorescent peaks. This approach is applicable to any type of linear algebra based fitting algorithm to fit spectra containing overlapping signals wherein the spectra also contain unimportant (non-characteristic) regions which add little (or no) weight to fitted values, e.g. energy regions in XRF spectra that contain little or no peak information.

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Lin, Haitao, Jun Huang et Liyun Ding. « Preparation of Carbon Dots with High-Fluorescence Quantum Yield and Their Application in Dopamine Fluorescence Probe and Cellular Imaging ». Journal of Nanomaterials 2019 (17 octobre 2019) : 1–9. http://dx.doi.org/10.1155/2019/5037243.

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Carbon dots represent a kind of fluorescent nanomaterial and have broad application prospects in the field of biosensing and optoelectronics. Here, we explored carbon dots with a high-fluorescence quantum yield rate synthesized from L-cysteine and citric acid by the microwave-assisted method. The characteristics of the carbon dots were studied using a transmission electron microscope, an X-ray diffractometer, X-ray photoelectron spectra, a UV-Vis absorption spectrometer, a FTIR spectrometer, and a fluorescence spectrophotometer. The obtained carbon dots exhibited a high-fluorescence quantum yield (up to 85%), which is due to the combination of amidogens and sulfydryl with carbon dots, and hence bring the improved fluorescence property. We used carbon dots for in vitro imaging of CRL-5822 cells and human umbilical vein endothelial cells, which showed the low inhibitory rate (0.8%) of cells for 48 h with good biocompatibility demonstrated by the cell viability assay. The image of cells can be observed clearly under UV light. The Stern-Volmer equation was introduced to describe the quenching effect between the fluorescence intensity of carbon dots and the concentration of aqueous dopamine (DA).

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Lee, Eun Sung, Byung Seok Cha, Seokjoon Kim et Ki Soo Park. « Synthesis of Exosome-Based Fluorescent Gold Nanoclusters for Cellular Imaging Applications ». International Journal of Molecular Sciences 22, n^o 9 (23 avril 2021) : 4433. http://dx.doi.org/10.3390/ijms22094433.

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In recent years, fluorescent metal nanoclusters have been used to develop bioimaging and sensing technology. Notably, protein-templated fluorescent gold nanoclusters (AuNCs) are attracting interest due to their excellent fluorescence properties and biocompatibility. Herein, we used an exosome template to synthesize AuNCs in an eco-friendly manner that required neither harsh conditions nor toxic chemicals. Specifically, we used a neutral (pH 7) and alkaline (pH 11.5) pH to synthesize two different exosome-based AuNCs (exo-AuNCs) with independent blue and red emission. Using field-emission scanning electron microscopy, energy dispersive X-ray microanalysis, nanoparticle tracking analysis, and X-ray photoelectron spectroscopy, we demonstrated that AuNCs were successfully formed in the exosomes. Red-emitting exo-AuNCs were found to have a larger Stokes shift and a stronger fluorescence intensity than the blue-emitting exo-AuNCs. Both exo-AuNCs were compatible with MCF-7 (human breast cancer), HeLa (human cervical cancer), and HT29 (human colon cancer) cells, although blue-emitting exo-AuNCs were cytotoxic at high concentrations (≥5 mg/mL). Red-emitting exo-AuNCs successfully stained the nucleus and were compatible with membrane-staining dyes. This is the first study to use exosomes to synthesize fluorescent nanomaterials for cellular imaging applications. As exosomes are naturally produced via secretion from almost all types of cell, the proposed method could serve as a strategy for low-cost production of versatile nanomaterials.

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Sripathi, Punchithaya K., et K. M. Balakrishna. « K-Shell X-Ray Fluorescence Studies of Some Elements in the Atomic Number Range 26 = Z = 70 ». International Journal of Chemoinformatics and Chemical Engineering 3, n^o 2 (juillet 2013) : 27–44. http://dx.doi.org/10.4018/ijcce.2013070102.

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K-shell fluorescence yields of low, medium Z and rare earth elements were determined using Si(PIN) detector and HPGe detector employing reflection geometry set up. Target atoms were excited using 59.5 keV gamma rays emerging from Am-241 source of strength 300 mCi. Background radiation and multiple scattering effects were minimized by properly shielding the detector. The elemental foils of uniform thickness and 99.9% purity were used in the present investigation. The fluorescent spectra were recorded in an 8K and 16K multi channel analyzer. The data were carefully analyzed and total K-shell fluorescence yields were calculated. The resulting yield values are compared with the available experimental and theoretical values.

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