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Literatura académica sobre el tema "Physico-chemical characterization by fluorescence"

Autor: Grafiati

Publicado: 25 de mayo de 2024

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Artículos de revistas sobre el tema "Physico-chemical characterization by fluorescence"

Daou, Claude, Mervat El Hoz, Amine Kassouf y Bernard Legube. "Multivariate Monitoring of Surface Water Quality: Physico-Chemical, Microbiological and 3D Fluorescence Characterization". Water 12, n.º 6 (11 de junio de 2020): 1673. http://dx.doi.org/10.3390/w12061673.

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The primary objective of this study is to explore a water quality database on two Mediterranean rivers (the Kadisha-Abou Ali and El Jaouz rivers—located in north Lebanon), considering their physicochemical, microbiological and fluorescence characteristics. Principal Component Analysis (PCA) was applied to the matrix gathering physicochemical and microbiological data while the Common Components and Specific Weight Analysis (CCSWA) or ComDim was used for fluorescence excitation-emission matrices (EEMs). This approach provided complementary and valuable information regarding water quality in such complex ecosystem. As highlighted by the PCA and ComDim scores, the Kadisha-Abou Ali River is highly influenced by anthropogenic activities because its watershed districts are intensively populated. This influence reveals the implication of organic and bacteriological parameters. To the contrary, the El Jaouz watershed is less inhabited and is characterized by mineral parameters, which determines its water quality. This work highlighted the relationship between fluorescence EEMs and major water quality parameters, enabling the selection of reliable water quality indicators for the studied rivers. The proposed methodology can surely be generalized to the monitoring of surface water quality in other rivers. Each customized water quality fingerprint should constantly be inspected in order to account for any emerging pollution.

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Staninski, Krzysztof y Stefan Lis. "Photophysical characterization of chosen Ln(III) macromolecular complexes". International Journal of Photoenergy 7, n.º 3 (2005): 147–51. http://dx.doi.org/10.1155/s1110662x0500022x.

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Spectral characterization of N,N′-Bis(2,4-dihydroxobenzylidene)1,2-diaminobenzene (DHDA) complexes with chosen f- and d-metal ions are described. Physico-chemical properties of a series of complexes were studied in methanol solution using UV-VIS, IR and fluorescence spectroscopy. It was found that the excitation and fluorescence spectra of DHDA in water and methanol after being exposed to ultraviolet radiation, show very obvious photochromism. The formation of 1 : 1 complexes between4,4′,4″,4‴-(porphine-5,10,15,20-tetrayl)-tetrakis benzoic acid, (TCPPH2) and La(III), Eu(III) and Yb(III) in methanolic solution, with the use of the spectrophotometric and spectrofluorimetric methods. The conditional stability constants of the complexes were studied by monitoring the spectral changes of energy and intensity of Q bands of the porphyrin.

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Bujor, Alexandru, Victorita Tecuceanu, Anamaria Hanganu y Petre Ionita. "Synthesis and Structural Analysis of a Nitrobenzofurazan Derivative of Dibenzo-18-Crown-6 Ether". Chemistry 4, n.º 4 (9 de diciembre de 2022): 1696–701. http://dx.doi.org/10.3390/chemistry4040110.

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Nitrobenzofurazan derivatives are well known for their fluorescence, whilst crown ethers are known for their complexing capacity toward cationic species. In this study, we present the synthesis and structural characterization of a new derivative containing both nitrobenzofurazan moieties and a crown ether core. The new compound was obtained from dibenzo-18-crown-6 ether, which was first nitrated, reduced to the corresponding amine, and subsequently derivatized with NBD. Structural analyses performed by IR, NMR, UV–Vis, and MS confirmed its structure and physico-chemical behavior toward the complexation of alkaline cations.

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Rabilou Souley Moussa, Zeinabou Mahamadou, Ousmaila Sanda Mamane, Issa Habou, Maman Mousbahou Malam Alma y Ibrahim Natatou. "Physico-chemical, mineralogical and structural characterization of a clay of Tanout (Zinder-Niger)". World Journal of Advanced Research and Reviews 16, n.º 2 (30 de noviembre de 2022): 1077–92. http://dx.doi.org/10.30574/wjarr.2022.16.2.1272.

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The objective of this study is to identify the different mineral phases, the structural and textural properties of natural clay of Tanout in Zinder region (Niger) in order to have mineralogical data allowing its valuation. The methodology is based on a physicochemical characterization by coupling several analysis techniques (preliminary analyses, X-ray fluorescence, X-ray diffraction, thermos- gravimetric analysis, scanning electron microscopy, Brunauer-Emmett-Teller by adsorption of N2 at 77 K). The results from these analyzes show that this clay has a low humidity rate, a low density, a slightly neutral pH in an aqueous medium and a high cation exchange capacity and is mainly composed of SiO2 (68.1%), Al2O3 (17.02%) and Fe2O3 (7.6%) with trace elements, the most important of which are: Zr (4150.6 ppm), Sr (470 ppm), Cu (380.2 ppm) and V (320ppm). It essentially consists of Kaolinite and Montmorillonite with impurities such as quartz and microclines. It has a specific surface of 441.1 m2.g-1 and 2288 m2.g-1 calculated according to the BET and Langmuir methods respectively, with porous volume varying from 0.0157 to 0.2597 cm3.g-1 and of pore size which varies from 1.847 to 6.182 nm calculated according to the methods (Barrett-Joyner-Halenda, Dubinin-Radushkevich, Dubinin-A, Horvath-Kawazoe and Saito-Foley). This clay has an important degree of crystallinity. These characteristics make it a potential material that can be used in water pollution control.

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Sousa, F. K. A., I. A. Silva, W. S. Cavalcanti, Gelmires Araújo Neves y Heber Carlos Ferreira. "Physico-Mineralogical Characterization: Bentonitic Clays Recently Found in Olivedos, Paraíba, Brazil". Materials Science Forum 820 (junio de 2015): 56–59. http://dx.doi.org/10.4028/www.scientific.net/msf.820.56.

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Used in various branches of the industry, bentonitic clays are considered a valuable mineral, used specially in the petroleum industry for manufacturing of fluids used the drilling of petroleum wells in long depth. Recently, a deposit of this valuable mineral was discovered in the town of Olivedos-PB. There are data that prove that this is a very poor and underdeveloped town. So, this work aims at the physico-mineralogical characterization of clays recently discovered and, this way, verify if they present similar characteristics which allow them to replace the clays from Boa Vista-PB, and if they can be used by the industry, thus bringing social development for that town. The characterization was made by means of the analysis of chemical composition by X-ray fluorescence (EDX), thermogravimetric and thermal differential analyses (TG and DTA), X-ray diffraction (XRD), cation-exchange capacity (CEC) and specific area (SA). The results show that the clays recently discovered in Olivedos-PB are polycationic clays, presenting MgO, CaO and K2O content, and that they are constituted by smectitic clay mineral, by quartz and kaolinite.

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Maravelaki, Pagona-Noni, Antonis Theologitis, Meral Budak Unaler, Chrysi Kapridaki, Kali Kapetanaki y James Wright. "Characterization of Ancient Mortars from Minoan City of Kommos in Crete". Heritage 4, n.º 4 (22 de octubre de 2021): 3908–18. http://dx.doi.org/10.3390/heritage4040214.

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This work characterizes ancient mortars used in construction of the Bronze Age Minoan port at Kommos in Crete. The port dates from c. 1850 BCE with port facilities at the harbor and residences on the Central hillside and the Hilltop. A Greek, Phoenician, and Roman sanctuary overlies the administrative center. The first step collected representative samples from the different construction phases, previous conservation interventions, exposure to different environmental factors, and different material composition. From these 10 mortar samples were analyzed using stereo- and digital microscopy, X-ray diffraction (XRD), X-ray Fluorescence (XRF), and Fourier Transform Infrared spectroscopy (FTIR) to determine texture, morphology, mineralogical, and physico-chemical properties. The physico-chemical and mineralogical analyses divided the samples into two groups: lime binder mortars and earthen binder mortars. The main minerals identified in the samples are calcite, quartz, dolomite, illite, albite, kaolinite, and vermiculite. Analysis of local clay showed that local materials were used in the production of these mortars. The analysis of mortar samples with stereomicroscopy, XRF, and FTIR showed that the samples are mainly composed of calcite and silicates in major quantities along with aluminum, magnesium, and iron oxide in minor quantities. A wide variety of local aggregates and ceramic fragments were used in the production of these ancient mortars. The mortar condition resulted in a decay state that needs conservation interventions. This characterization of the ancient mortars was important for the design of compatible restoration mortars.

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Dadi, Nitin Chandra teja, Matúš Dohál, Veronika Medvecká, Juraj Bujdák, Kamila Koči, Anna Zahoranová y Helena Bujdáková. "Physico-Chemical Characterization and Antimicrobial Properties of Hybrid Film Based on Saponite and Phloxine B". Molecules 26, n.º 2 (10 de enero de 2021): 325. http://dx.doi.org/10.3390/molecules26020325.

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This research was aimed at the preparation of a hybrid film based on a layered silicate saponite (Sap) with the immobilized photosensitizer phloxine B (PhB). Sap was selected because of its high cation exchange capacity, ability to exfoliate into nanolayers, and to modify different surfaces. The X-ray diffraction of the films confirmed the intercalation of both the surfactant and PhB molecules in the Sap film. The photosensitizer retained its photoactivity in the hybrid films, as shown by fluorescence spectra measurements. The water contact angles and the measurement of surface free energy demonstrated the hydrophilic nature of the hybrid films. Antimicrobial effectiveness, assessed by the photodynamic inactivation on hybrid films, was tested against a standard strain and against methicillin-resistant bacteria of Staphylococcus aureus (MRSA). One group of samples was irradiated (green LED light; 2.5 h) and compared to nonirradiated ones. S. aureus strains manifested a reduction in growth from 1-log10 to over 3-log10 compared to the control samples with Sap only, and defects in S. aureus cells were proven by scanning electron microscopy. The results proved the optimal photo-physical properties and anti-MRSA potential of this newly designed hybrid system that reflects recent progress in the modification of surfaces for various medical applications.

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Ayanda, Fatai Arolu, Mohd Firdaus Mohd Anuar, Syaharudin Zaibon y Shamshuddin Jusop. "The Physico-Chemical and Mineralogical Characterization of Mg-Rich Synthetic Gypsum Produced in a Rare Earth Refining Plant". Sustainability 13, n.º 9 (26 de abril de 2021): 4840. http://dx.doi.org/10.3390/su13094840.

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The physical, chemical and mineralogical characterization of the constituents of magnesium-rich synthetic gypsum produced in a rare earth-refining plant located in Gebeng, Pahang, Malaysia was conducted through elemental chemical analysis, scanning electron microscopy with Energy Dispersive X-ray (EDX)-analyzer, thermal analysis, X-ray fluorescence and X-ray diffraction. The crystalline nature of the by-product was studied using FTIR spectroscopy. Elemental analysis confirmed the presence of Ca and Mg, which are essential macronutrients required by plants and this Ca alongside the high pH (9.17) of MRSG may confer on the material a high acid neutralization capacity. From the result, it was observed that the studied by-product is a heterogeneous crystalline material comprising of gypsum (CaSO4.2H2O) and other major components such as calcium (magnesium) compounds (hydroxide, oxide, silicates, and carbonate) and sulfur. These aggregates may contribute to give an acid neutralization capacity to MRSG. The XRD study of MRSG indicated a high content of gypsum (45.4%), shown by the d-spacing of 7.609 Å (2-theta 11.63) in the diffractogram. The infrared absorption spectra of MRSG indicate close similarities to mined gypsum. The results of the characterization indicated that MRSG has valuable properties that can promote its use in amending soil fertility constraints on nutrient-deficient tropical acid soils.

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Sena, Andressa S., Bacus Nahime, Elton C. Lima, Fausto A. Lobo, Jorge L. Akasaki y Igor S. dos Santos. "Characterization of briquettes produced from eucalyptus wood waste generated in agro-industries". Revista Brasileira de Engenharia Agrícola e Ambiental 25, n.º 11 (noviembre de 2021): 794–98. http://dx.doi.org/10.1590/1807-1929/agriambi.v25n11p794-798.

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ABSTRACT Boilers are widely used by industries and thermoelectric plants to generate renewable energy. However, when biomass is consumed, residues are generated, which for the most part cannot be discarded appropriately. This study investigated the reuse of eucalyptus wood waste with the goal of transforming the residue into resistant and durable briquettes for reuse in furnaces and boilers. The physico-chemical properties of the residue were studied in terms of chemical composition by X-ray fluorescence, and its crystalline structure was evaluated by X-ray diffraction. Both thermogravimetric analysis and differential thermogravimetric analysis were used to characterize the thermal decomposition of the wood waste residue. The residue was compacted in a universal press with sufficient humidity to fabricate briquettes under different conditions of mechanical pressure. Apparent density, durability, and burning tests were carried out on the briquettes. The maximum temperature reached during burning is dependent on the fabrication compaction pressure. The briquettes proved suitable for burning in boilers and furnaces, and their durability is advantageous for handling, reuse, and transportation.

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Tesis sobre el tema "Physico-chemical characterization by fluorescence"

Gouisset, Emmanuel. "Développement et étude de la réponse instrumentale d'un imageur hyperspectral large bande (UV-Visible-NIR) permettant la caractérisation physico-chimique de contaminants sur surfaces sensibles d’engins orbitaux". Electronic Thesis or Diss., Sorbonne université, 2022. http://www.theses.fr/2022SORUS139.

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Dans le domaine de l’analyse de défaillance et plus particulièrement la contamination moléculaire et particulaire, il est crucial de pouvoir détecter toute trace de contaminants durant l’intégration d’un engin orbital. Dans ce contexte, la fluorescence permet non seulement de détecter mais aussi de discriminer les contaminants. Pour ce projet, nous avons donc développé un instrument hyperspectral large-bande (UV-Vis-NIR) de 330 à 1000 nm pour pouvoir détecter un large panel de contaminants. Il s’agit d’un montage catoptrique permettant de s’affranchir des aberrations chromatiques. Il présente un champ de vue de 3,5° pour une résolution angulaire de 25 secondes d’arc. Il a été conçu pour être portable et son ensemble mécanique figé permet un alignement optique simple à mettre en œuvre et une réalisation rapide des fichiers de calibration entre deux scènes. Nous avons mesuré une résolution spectrale de 1 nm dans l’UV, 2 à 3 nm dans le visible et 5 nm dans le NIR. Cela nous a permis d’étudier la réponse en fluorescence de deux colles époxy, sources typiques de la contamination d’engin orbital et de la comparer avec une mesure obtenue avec un instrument commercial. Ces mesures nous ont permis d’évaluer les performances de notre instrument et d’identifier des perspectives d’amélioration, notamment en termes de sensibilité dans les UV
In the field of failure analysis and in particular molecular and particulate contamination, being able to detect any trace of contaminants during the integration of an orbital spacecraft is crucial. In this context, fluorescence allows not only to detect but also to discriminate contaminants. For this project, we have therefore developed a broadband hyperspectral instrument (UV-Vis-NIR) from 330 to 1000 nm to be able to detect a wide range of contaminants. It is a catoptric assembly that eliminates chromatic aberrations. The field of view is 3.5° for an angular resolution of 25 arc seconds. It was designed to be portable and its fixed mechanical assembly allows easy optical alignment and rapid creation of calibration files between two scenes. We measured a spectral resolution of 1 nm in the UV range, 2 to 3 nm in the visible range and 5 nm in the NIR range. This allowed us to study the fluorescence response of two epoxy glues, typical sources of orbital spacecraft contamination, and to compare it with a measurement obtained with a commercial instrument. These measurements allowed us to evaluate the performance of our instrument and identify prospects of improvement, especially in terms of sensitivity in UV range

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Ezhilan, Madhumitha. "Commissioning a Commercial Laser Induced Fluorescence System for Characterization of Static Mixer Performance". University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1499793560290147.

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Deighan, Clayton J. "Particle Balances in Therapeutic Extracellular Vesicle Development and in depth Characterization of Fluorescence Nanoparticle Tracking Analysis". The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1440158128.

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Chu, Manh-Hung. "Structural and chemical characterization of single Co-implanted ZnO nanowires by a hard X-ray nanoprobe". Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENY016/document.

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Ce travail de thèse porte sur l'analyse de nanofils de ZnO dopés au cobalt par implantation ionique, en utilisant la fluorescence des rayons X, la spectroscopie d'absorption des rayons X et les techniques de diffraction des rayons X à l'échelle nanométrique sur la ligne de lumière ID22 de l'Installation Européenne de Rayonnement Synchrotron. Les nanofils sont obtenus par croissance catalysée sur des substrats de p-Si (100). Les nanofils de ZnO synthétisés ont été dopés avec du cobalt par d'implantation ionique. Pour la première fois, l'utilisation combinée des techniques de caractérisation par rayons X citées ci-dessus nous permet d'étudier l'homogénéité de la distribution des dopants, la composition, ainsi que l'ordre structurel à courte et grande distance de nanofils individuels. Les résultats de la nano-fluorescence des rayons X indiquent que le dopage au cobalt par implantation ionique dans les nanofils de ZnO est homogène, avec les concentrations désirées. La spectroscopie d'absorption de rayons X et l'analyse des données de diffraction de rayons X fournissent de nouvelles informations sur la distorsion du réseau cristallin produite par l'introduction de défauts structuraux par le processus d'implantation ionique. Ces résultats soulignent l'importance du recuit thermique après l'implantation pour récupérer la structure des nanofils de ZnO à l'échelle du nanomètre. Les mesures complémentaires de micro-photoluminescence et cathodo-luminescence corroborent ces résultats. En conclusion, les méthodes utilisées dans cette thèse ouvrent de nouvelles voies pour l'application de mesures multi-techniques basées sur le rayonnement synchrotron pour l'étude détaillée des nanofils semi-conducteurs à l'échelle nanométrique
The PhD dissertation focuses on the investigation of single Co-implanted ZnO nanowires using X-ray fluorescence, X-ray absorption spectroscopy, and X-ray diffraction techniques with nanometer resolution at the beamline ID22 of the European Synchrotron Radiation Facility. The ZnO nanowires were grown on p-Si (100) substrates using vapor-liquid-solid mechanism. The synthesized ZnO nanowires were doped with Co via an ion implantation process. For the first time, the combined use of these techniques allows us to study the dopant homogeneity, composition, short- and large-range structural order of individual nanowires. The nano-X-ray fluorescence results indicate the successful and homogeneous Co doping with the desired concentrations in the ZnO nanowires by an ion implantation process. The nano-X-ray absorption spectroscopy and X-ray diffraction data analyses provide new insights into the lattice distortions produced by the structural defect formation generated by the ion implantation process. These findings highlight the importance of the post-implantation thermal annealing to recover the structure of single ZnO nanowires at the nanometer length scale. Complementary microphotoluminescence and cathodoluminescence measurements corroborrate these results. In general, the methodologies used in this work open new avenues for the application of synchrotron based multi-techniques for detailed study of single semiconductor nanowires at the nanoscale

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Sun, Xiaojiao. "Single molecule studies of acidity in heterogeneous catalysts". Diss., Kansas State University, 2013. http://hdl.handle.net/2097/16423.

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Doctor of Philosophy
Department of Chemical Engineering
Keith L. Hohn
Amorphous silica-alumina is widely used as a solid acid catalyst for various reactions in oil refining and the petrochemical industry. The strength and the number of the acid sites in the material are most often believed to arise from the alumina atoms inserted into the silica lattice. The existence of the acidity distribution across the framework is a result of the local composition or the short-range interactions on the silica-alumina surface. Conventional techniques used to characterize silica-alumina provide effective information on the average acidity, but may not reflect the heterogeneity of surface acidity within the material. Recently, it is possible to study individual catalytic sites on solid catalysts by single molecule fluorescence microscopy with high time and space resolution. Fluorophores can be chosen that emit at different wavelengths depending on the properties of the local environment. By doping these fluorophores into a solid matrix at nanomolar concentrations, individual probe molecules can be imaged. Valuable information can be extracted by analyzing changes in the fluorescence spectrum of the guest molecules within a host matrix. In this research, silica-alumina thin films were studied with single molecule fluorescence microscopy. The samples were prepared by a sol-gel method and a wide-field fluorescence microscope was used to locate and characterize the fluorescent behaviors of pH sensitive probes. In mesoporous thin films, the ratio of the dye emission at two wavelengths provides an effective means to sense the effective pH of the microenvironment in which each molecule resides. The goal of this work was to develop methods to quantify the acidity of individual micro-environments in heterogeneous networks. Pure silica films treated with external phosphate solutions of different pH values were used to provide references of the fluorescence signals from individual dye molecules. SM emission data were obtained from mesoporous Al-Si films as a function of Al content in films ranging from 0% to 20% alumina. Histograms of the emission ratio revealed that films became more acidic with increasing Al content. The acidity on interior surfaces in zeolite pores was also of interest in this work. A microfluidic device was built to isolate the interior surface from the exterior surface. Some preliminary results showed the potential of using SM fluorescence method to study the acidic properties inside the pores of zeolite crystals.

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Morel, Oriane. "Characterization of the spatial distribution of lignins in plant cell walls using chemical reporters and Raman". Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILS118.

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La lignine est un polymère polyphénolique de la paroi cellulaire qui intervient dans de nombreux aspects de la croissance et du développement des plantes supérieures. En tant que composant majeur de la biomasse lignocellulosique, elle présente également un intérêt économique. Bien que la biosynthèse du polymère de la lignine soit relativement bien comprise, nous avons besoin d'en savoir plus sur la façon dont les changements (quantité/structure) des autres polymères de la paroi cellulaire (par exemple, la cellulose, les hémicelluloses, les pectines) affectent la production de lignine. Afin de fournir plus d'informations sur cette question, nous avons mis en œuvre une approche en deux phases basée sur l'utilisation de l'imagerie biologique. La première phase a consisté à développer/améliorer différentes techniques d'imagerie complémentaires à haute résolution. Nous avons tout d'abord développé une nouvelle approche ratiométrique quantitative (REPRISAL) basée sur la segmentation paramétrique/intelligence artificielle d'images de microscopie confocale obtenues par la chimie bio-orthogonale des rapporteurs chimiques de la lignine (click chemistry). Cette méthodologie nous a permis de cartographier précisément la capacité de lignification des différentes couches de la paroi cellulaire (coin cellulaire, lamelle moyenne composée et paroi cellulaire secondaire) chez les plantes Arabidopsis WT et le mutant prx64. Dans un deuxième temps, nous avons modifié l'algorithme de segmentation REPRISAL afin de pouvoir l'utiliser pour cartographier les niveaux relatifs de lignine de la paroi cellulaire déterminés par la technique de fluorescence ratiométrique de la safranine-O. Enfin, nous avons utilisé l'imagerie Raman pour comparer la capacité de trois méthodes analytiques multivariées différentes (non-mixage, analyse en grappes et correspondance orthogonale) à fournir des informations spatiales détaillées sur la distribution des différents polymères dans les parois cellulaires des plantes. Dans la deuxième phase, nous avons utilisé les techniques d'imagerie développées/améliorées pour analyser si les modifications des hémicelluloses de la paroi cellulaire affectent la lignification chez le mutant irx9 d'Arabidopsis. Nos résultats ont démontré que les changements dans la distribution des hémicelluloses de la paroi cellulaire modifient effectivement le processus de lignification, en particulier dans les parties les plus jeunes de la tige florale de la plante. La transcriptomique ciblée de certains gènes de la paroi cellulaire suggère que les changements observés pourraient être liés à l'induction d'une réponse de défense. Globalement, les techniques développées dans le cadre de cette thèse devraient s'avérer précieuses pour les études futures de la dynamique des parois cellulaires. Les résultats obtenus sur le mutant irx9 donnent un nouvel aperçu des relations dynamiques qui existent entre les différents polymères de la paroi cellulaire des plantes
Lignin is a polyphenolic polymer of the cell wall involved in many aspects of growth and development in higher plants. As a major component of lignocellulosic biomass, it is also of economic interest. Although the biosynthesis of the lignin polymer is relatively well understood, we need to know more about how changes (quantity/structure) to other cell wall polymers (e.g., cellulose, hemicelluloses, pectins) affect lignin production. To provide more information on this question we implemented a two-phase approach based on the use of biological imaging. The first phase involved the development/improvement of different high-resolution complementary imaging techniques. We firstly developed a novel quantitative ratiometric approach (REPRISAL) based on the parametric/artificial intelligence segmentation of confocal microscopy images obtained by lignin chemical reporter bio-orthogonal chemistry. This methodology allowed us to precisely map the lignification capacity of different cell wall layers (cell corner, compound middle lamella and secondary cell wall) in Arabidopsis WT plants and the prx64 mutant. In a second development, we modified the REPRISAL segmentation algorithim thereby enabling it to be used to map relative cell wall lignin levels determined by the ratiometric safranin-O fluorescence technique. Finally, we used Raman imaging to compare the ability of three different multivariate analytical methods (unmixing, cluster analysis and orthogonal matching) to provide detailed spatial information about the distribution of different polymers in plant cell walls. In the second phase we used the developed/improved imaging techniques to analyse whether changes to cell wall hemicelluloses affect lignification in the Arabidopsis irx9 mutant. Our results demonstrated that changes in the distribution of cell wall hemicelluloses do indeed modify the lignification process, particularly in the younger parts of the plant floral stem. Targeted transcriptomics of selected cell wall genes suggested that the observed changes could be related to the induction of a defence response. Overall, the techniques developed within the framework of this thesis should prove valuable for future studies of cell wall dynamics. The results obtained on the irx9 mutant provide a novel insight into the dynamic relationships that exist between different polymers of the plant cell wall

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Pirone, Frederick S. "Trade, Interaction and Change: Trace Elemental Characterization of Maltese Neolithic to Middle Bronze Age Ceramics Using a Portable X-ray Fluorescence Spectrometer". Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/6930.

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The insular nature of the Maltese archipelago provides a unique opportunity to explore trade and cultural change from the Neolithic to the Bronze Ages in the central Mediterranean. I hypothesize that, during the period in which the Maltese islands were experiencing a form of isolation—owing either to their distance from Sicily and other populated regions, to the collective formation of an inwardly-focused culture, or to a combination of these factors—it is unlikely that pottery played a significant role as either an import or export in the archipelago’s exchange relationships with other communities in the central Mediterranean. I accordingly propose that ceramics were only significant in the interaction networks between Malta and its neighbors during periods when the archipelago was culturally connected to Sicily. Except for a limited number of archaeometric studies (Barone et al. 2015; Molitor 1988; Mommsen et al. 2006), analysis of similarities among ceramic wares produced in Malta and elsewhere that allow archaeologists to draw conclusions about the nature of Malta’s connectivity to other communities has been based on macroscopic observation. The present study builds on the few archaeometric studies by determining the provenance of ceramic samples based on their trace elemental composition. Included in this study were both clay samples and ceramic artifacts representing each of Malta’s chronological phases from the Neolithic to the Bronze Ages. Specifically, in order to address the question of the role that pottery played in the prehistoric trade of the Maltese islands, 392 Maltese ceramic sherds were analyzed using a Bruker III-V handheld portable X-ray fluorescence device, which revealed the relative abundance of six trace elements, namely thorium, rubidium, strontium, yttrium, zirconium, and niobium. The trace elemental composition of the Maltese pottery was compared with that of 18 Sicilian ceramic sherds and clay samples from both Malta and Sicily. The results of this research support my hypothesis in part, suggesting that neither ceramics nor raw clay materials played a significant role in overseas trade during Malta’s period of cultural isolation, which extended from the Ġgantija phase to the end of the Tarxien phase. On the other hand, ceramics played a more active role in Malta’s interaction networks during periods of connectivity with Sicily, for instance in the Neolithic Age. This study also provides the first chemical evidence that Malta exported pottery to Sicily during the Bronze Age and that Malta’s contact with Mycenaeans was indirect in nature. The findings presented here thus contribute to understanding Malta’s role in trade and interaction networks from the Neolithic to the Bronze Ages and point to new approaches to exploring the cultural change that becomes apparent in the Maltese Temple Period.

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Irimiea, Cornelia. "Characterization of soot particles and their precursors by coupling laser-based techniques". Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10066.

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Les processus de combustion ont un impact important sur la qualité de l’air, le climat ou l’utilisation des sources d’énergie. Malgré les progrès réalisés pour une combustion plus propre, les chemins réactionnels conduisant à la formation des polluants (notamment des particules de suie) ne sont pas encore complétement élucidés. L’objectif de ce travail est d’étudier la formation des suies et de leurs précurseurs dans des flammes de laboratoire pour une meilleure compréhension fondamentale des mécanismes impliqués dans la transition de la phase gaz à la phase particulaire. Le même objectif est poursuivi dans des campagnes de terrain pour évaluer l’impact potentiel des propriétés de surface des suies sur l’environnement. Nous utilisons des techniques d’analyse in-situ (incandescence et fluorescence induites par laser) et ex-situ (spectrométrie de masse couplée à la désorption laser ou ionique) pour mettre en évidence des propriétés spécifiques des suies et de leurs précurseurs. L’évolution de l’indice de réfraction complexe avec le stade de la combustion est mesurée, et ses implications sur la physico-chimie de la flamme et sur les techniques analytiques sont discutées. Une nouvelle méthode de détection basée sur l’excitation simultanée de la suie et des précurseurs à une seule longueur d’onde est proposée. La composition chimique de surface des suies émises par des moteurs utilisés dans les transports terrestres et aériens est également analysée. Des méthodes statistiques multivariées sont utilisées pour identifier des tendances communes et des différences dans les échantillons étudiés, en faisant ressortir l’influence du carburant ou des paramètres de combustion
Combustion impacts many important aspects of our life like the air quality, the local and global climate and the use of energy sources. In the last decades, an outstanding progress towards cleaner combustion has been achieved. However, the reaction pathways leading to the formation of some pollutants, especially particulate matter (soot) resulting from incomplete combustion, are still elusive. In this work, we aim to investigate specific aspects of soot and its precursors formation in laboratory flames for a fundamental understanding of the mechanisms leading from the gas phase up to the mature particulate found in the exhausts. This objective is also pursued in field-campaigns to assess the potential impact of soot surface properties on the environment. Following this approach, experimental techniques like in-situ laser induced incandescence and fluorescence, and ex-situ laser desorption and secondary ion mass spectrometry are used to target specific properties of soot and its precursors. Notably, the evolution of the complex refractive index of soot is measured as a function of soot maturity, and the implications on both the flame physico-chemistry and the analytical techniques applicability are discussed. Additionally, a new detection method for soot and precursors based on simultaneous excitation at one wavelength is developed. In parallel, two campaigns are dedicated to the analysis of the surface chemistry of soot sampled from airplane and car exhausts. Statistical methods as multivariate analysis are used to identify patterns and differences within sets of samples by assessing the influence of the combustion parameters or the role of the fuel

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McDonald, Lucas J. "Synthesis and Characterization of Novel Flavonoid-Based Fluorescent Sensors and other Sensors with Excited State Intramolecular Proton Transfer for Biological Applications". University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1524658238472646.

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Shoghi, Kalkhoran Elham. "Physico-Chemical Characterization of Drugs: Acidity and Solubility". Doctoral thesis, Universitat de Barcelona, 2013. http://hdl.handle.net/10803/98463.

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The aim of the present work was to contribute to establish robust and high throughput methodology of interest in the "Drug Discovery" step commonly done in pharmaceutical laboratories. This purpose involves the exploration of the possibilities of the potentiometric Sirius methodology to determine both acidity constants and solubilities of drugs and other bioactive compounds and also to do a study about how to improve bioavailability of a model drug, Amphotericine 8, by increasing its dissolution rate. In the first part of this project, the acidic dissociation enthalpies and constants of anilinium, protonated tris (hydroxymethyl)- aminomethane (HTris+), benzoic and acetic acids, have been determined at several temperatures in pure water and in methanol/water mixtures by potentiometry method. The pK(a) values determined by this technique are in accordance with those values determined by ITC method in our laboratory and also with those other values from literature. Also dissociation enthalpies can be obtained from potentiometric pK(a) values by means of the Van't Hoff approach and these obtained values are in agreement with those ones determined directly by calorimetry in our laboratory. In the second part, we focused on studying about solubility. The Chasing Equilibrium method offers an alternative to the classical procedures to measure the solubility of compounds with acid-base properties. The method is fast and yields accurate results. In this work, the solubility of several compounds including acids and bases was determined through the Chasing Equilibrium approach. A study of experimental conditions in terms of sample weight was performed to measure solubilities. The study shows that only a limited range of weights, depending on the nature and solubility of the compounds, is adequate to obtain reliable results. In the third part of this work, the solubility vs. pH profiles of five ionizable drugs of different nature (a monoprotic acid, a monoprotic base, a diprotic base and two amphoteric compounds showing a zwitterionic species each one) have been determined through two different methodologies: the classical Shake-Flask (S-F) and the potentiometric Cheqsol methods using in both instances the appropriate Henderson-Hasselbalch (H-H) or derived relationships. The results obtained independently from both approaches are consistent. A critical revision about the influence of the electrolyte used as buffering agent in the S-F method on the obtained solubility values is also performed. Thus, some deviations of the experimental points with respect the H-H profiles can be attributed to specific interactions between the buffering electrolyte and the drug due to the hydrotrophic character of citric and lactic acids. In other cases, the observed deviations are independent of the buffers used since they are caused by the formation of new species such as drug aggregates (cefadroxil) or the precipitation of a salt from a cationic species of the analysed compound (quetiapine). In the forth part, the objective was to compare the dissolution behavior of tablets prepared from solid dispersions prepared in DMSO dissolvent with and without drug-carrier and also with and without surfactants in aqueous and acidic solutions. Amphotericine B was used as a model drug. Two types of carriers were used; mannitol, inulin. Solid dispersions with two different drug loads were prepared by freeze drying method. It was found that the drug dissolution rate in aqueous and acidic solutions was significantly increased in the presence of drug-carrier and surfactants. X-ray powder diffraction revealed that all solid dispersions were fully amorphous.
El objetivo del presente trabajo ha sido contribuir a establecer metodología robusta y de high throughput de interés en la etapa conocida como "Drug Discovery" que tiene lugar en los laboratorios farmacéuticos al inicio del proceso de desarrollo de nuevos fármacos. Este objetivo ha implicado la exploración de las posibilidades de la metodología potenciométrica establecida y comercializada por Sirius Analytical Ltd. para la determinación de las constantes de acidez y de la solubilidad de compuestos bioactivos y también un estudio sobre la mejora de la biodisponibilidad de un fármaco muy insoluble tomado como modelo mediante el aumento de su velocidad de disolución. En la primera parte de esta Tesis se han determinado potenciométricamente las constantes de disociación ácida y la variación de entalpía asociada de dos bases y dos ácidos tomados como modelo en agua pura y en mezclas de metanol/agua (0-60% w/w) a varias temperaturas (25-55°C). Esto ha implicado la puesta a punto de la estandarización del sistema potenciométrico en las condiciones de trabajo. Los valores de pK(a) determinados son concordantes con los que ofrece la literatura. Se han calculado también las entalpias de disociación en los distintos solventes binarios estudiados mediante la ecuación de Van't Hoff a partir de los valores experimentales de pK(a). La consistencia de los resultados obtenidos con los de la literatura, obtenidos directamente por calorimetría, confirma la robustez de la metodología. En la segunda parte de este trabajo, el estudio se centró sobre la determinación potenciométrica de la solubilidad de ácidos y bases mediante el método conocido como Chasing Equilibrium, como alternativa a los procedimientos clásicos de equilibración. El método es rápido y produce resultados precisos. Se ha realizado un estudio sobre las condiciones experimentales óptimas en términos de peso de la muestra para medir eficazmente la solubilidad. El estudio muestra que, en función de la naturaleza y solubilidad de los compuestos, existe un intervalo limitado de peso de muestra adecuado para obtener resultados fiables. En la tercera parte de la presente memoria, se estudian los perfiles de solubilidad en función del pH de cinco fármacos ionizables de naturaleza diferente, un ácido y una base monopróticos, una base diprótica y dos compuestos anfóteros que muestran una especie zwitteriónica cada uno. Se han determinado los perfiles de solubilidad mediante el método clásico de equilibración (Shake-Flak, S-F) y el potenciómétrico y, en ambos casos, se han utilizado las relaciones apropiadas de Henderson-Hasselbalch (H-H) o derivadas. Los resultados obtenidos de forma independiente por ambos métodos son consistentes. Se ha hecho un estudio crítico acerca de la influencia del electrolito utilizado como agente tampón en el método S-F en los valores de solubilidad obtenidos y se han observado algunas desviaciones de los puntos experimentales con respecto a los perfiles esperados que pueden ser debidas a interacciones específicas entre el electrolito tampón y el fármaco. En otros casos, las desviaciones observadas son independientes de los tampones utilizados y se pueden atribuir a la formación de nuevas especies tales como agregados iónicos del fármaco en estudio o la precipitación de una sal a partir de una especie catiónica del compuesto analizado. En la cuarta parte de esta memoria el objetivo ha sido estudiar la velocidad de disolución de comprimidos preparados a partir de dispersiones sólidas de un fármaco modelo con y sin portador del fármaco y también en presencia y en ausencia de tensioactivo en soluciones acuosas neutras y ácidas. Como fármaco modelo se estudió la Anfotericina B y se utilizaron como portadores manitol e inulina y como tensioactivos se ensayaron el deoxicolato de sodio (SDC) y el laurilsulfato de sodio (SLS). La difracción de rayos X reveló que el fármaco en estudio se hallaba en estado amorfo en todas las dispersiones sólidas estudiadas. Se puede concluir que la velocidad de disolución del fármaco se incrementa significativamente en presencia de portador y tensioactivo.

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Libros sobre el tema "Physico-chemical characterization by fluorescence"

Dickinson, Eric, ed. New Physico-Chemical Techniques for the Characterization of Complex Food Systems. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4615-2145-7.

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Eric, Dickinson, ed. New physico-chemical techniques for the characterization of complex food systems. London: Blackie Academic & Professional, 1995.

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Banaras Hindu University. Centre of Advanced Study in Botany. y India. Dept. of Environment., eds. Physico-chemical and biological characterization of River Ganga in relation to pollution. Varanasi, India: Centre of Advanced Study in Botany, Banaras Hindu University, 1989.

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DiTizio, Valerio. Characterization of the effects of paclitaxel on the physico-chemical properties of phospholipid bilayers. Ottawa: National Library of Canada, 1995.

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Dillian, Carolyn. Current Questions and New Directions in Archaeological Obsidian Studies. Oxford University Press, 2016. http://dx.doi.org/10.1093/oxfordhb/9780199935413.013.2.

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This article discusses the current status of archaeological obsidian studies, including techniques used in characterization and sourcing studies, obsidian hydration, and regional syntheses. It begins with an overview of obsidian and the unique formation processes that create it before turning to a discussion of the significance of characterization and sourcing techniques for understanding prehistoric obsidian trade and exchange. It then considers the problematic aspects of the term “sourcing,” despite its ubiquitous use in archaeology and archaeometry, along with the use of X-ray fluorescence in the chemical characterization of obsidian. It also explores obsidian hydration dating methods and equations, factors that can affect the date assignments for hydration specimens, and the various uses of obsidian in prehistoric times. Finally, it addresses some important questions relating to obsidian research and suggests new directions in the field.

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Iseghem, P. Van, K. Berghman y W. Timmermans. Physico-chemical Characterization of Bituminized Eurochemic Medium-level Waste. European Communities / Union (EUR-OP/OOPEC/OPOCE), 1991.

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Thakur, Vijay Kumar, Manju Kumari Thakur y Michael R. Kessler. Handbook of Composites from Renewable Materials, Physico-Chemical and Mechanical Characterization. Wiley & Sons, Incorporated, John, 2017.

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Dickinson, E. New Physico-Chemical Techniques for the Characterization of Complex Food Systems. Springer, 2012.

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Handbook of Composites from Renewable Materials, Physico-Chemical and Mechanical Characterization. Wiley-Scrivener, 2017.

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Capítulos de libros sobre el tema "Physico-chemical characterization by fluorescence"

Sakurai, Kenji y Atsuo Iida. "Near-Surface Chemical Characterization using Grazing Incidence X-Ray Fluorescence". En Advances in X-Ray Analysis, 205–11. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4613-9996-4_23.

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Acquafredda, Pasquale y F. Javier Huertas. "X-Ray Fluorescence: Chemical Characterization of Materials by X-Ray Spectrometry". En Mineralogical Analysis Applied to Forensics, 225–50. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-08834-6_8.

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Mayoux, Christine y Christian Mayoux. "Physico-Chemical Characterization Techniques of Dielectrics". En Dielectric Materials for Electrical Engineering, 325–46. Hoboken, NJ USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118557419.ch15.

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Marchand, A. "Physico-Chemical and Structural Characterization of Carbons". En Carbon and Coal Gasification, 93–136. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-4382-7_4.

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Cecchi, Teresa. "Physico-chemical Characterization of Bioplastics and Biocomposites". En Biobased Products from Food Sector Waste, 323–40. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-63436-0_9.

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Reijnders, H. F. R., J. Van Zijl, W. A. J. Van Pul, F. G. Romer y H. J. Slangewal. "Characterization of Cloud and Rain Water Chemical Composition". En Physico-Chemical Behaviour of Atmospheric Pollutants, 451–59. Dordrecht: Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-3841-0_50.

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Papenbrock, Th y F. Stuhl. "Detection of Nitric Acid in Air by a Laser-Photolysis Fragment-Fluorescence (LPFF) Method". En Physico-Chemical Behaviour of Atmospheric Pollutants, 651–56. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0567-2_98.

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Papenbrock, Th y F. Stuhl. "Detection of Gaseous Nitric Acid by OH(A→X) — Fluorescence Generated by ArF-Laser Irradiation". En Physico-Chemical Behaviour of Atmospheric Pollutants, 5–14. Dordrecht: Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-3841-0_2.

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Ravaglioli, A., A. Krajewski, A. Piancastelli y R. Martinetti. "Physico-Chemical Characterization of Hydroxyapatite of Unknown Manufacture". En Bioceramics and the Human Body, 203–5. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-2896-4_25.

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Karge, H. G. y J. B. Nagy. "Characterization of Structural and Physico-Chemical Properties of Zeolitic Systems". En Guidelines for Mastering the Properties of Molecular Sieves, 387–94. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4684-5787-2_25.

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Actas de conferencias sobre el tema "Physico-chemical characterization by fluorescence"

Soumbo, Marvine, Alessandro Pugliara, Marie-Carmen Monje, Christine Roques, Bernard Despax, Caroline Bonafos, Robert Carles, Adnen Mlayah y Kremena Makasheva. "Physico-chemical characterization of the interaction of red fluorescent protein — DsRed with silica layers". En 2015 IEEE Nanotechnology Materials and Devices Conference (NMDC). IEEE, 2015. http://dx.doi.org/10.1109/nmdc.2015.7439280.

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Li, Minghe, Aleksandr Razumtcev, Dustin M. Harmon y Garth J. Simpson. "Fast diffusion characterization by fluorescence recovery while photobleaching (FRWP)". En Advanced Chemical Microscopy for Life Science and Translational Medicine 2023, editado por Garth J. Simpson, Ji-Xin Cheng y Wei Min. SPIE, 2023. http://dx.doi.org/10.1117/12.2649098.

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Prenting, Markus, Thomas Dreier y Christof Schulz. "Characterization of tracers for two-color laser-induced fluorescence liquid-phase temperature imaging in sprays". En Laser Applications to Chemical, Security and Environmental Analysis. Washington, D.C.: OSA, 2020. http://dx.doi.org/10.1364/lacsea.2020.lth5f.2.

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Fan, Zhu y Jürgen Krahl. "P2.3.12 Characterization and Identification of Diesel Fuels, Biodiesel and their Blends by Time-Resolved Laser-Induced Fluorescence Spectroscopy". En 14th International Meeting on Chemical Sensors - IMCS 2012. AMA Service GmbH, Von-Münchhausen-Str. 49, 31515 Wunstorf, Germany, 2012. http://dx.doi.org/10.5162/imcs2012/p2.3.12.

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Young, C. A., Q. Yu, K. Knutson y J. D. Miller. "Laser Applications of Vibrational Spectroscopy to Mineral and Coal Processing". En Laser Applications to Chemical Analysis. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/laca.1992.pd9.

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The spectroscopic analysis of mineral and coal samples from various process operations has received much attention worldwide. Our research group is presently using four vibrational spectroscopic techniques for the in-situ characterization of these samples and their surfaces. These techniques involve Fourier-transform infrared (FT-IR), Fourier-transform Raman (FT- Raman), low-intensity Raman (LIRS), and scanning fluorescence (SFS) spectroscopies, each of which incorporate lasers for interferometry and/or sample excitation purposes. The fundamentals behind each of these techniques are reviewed, thereby demonstrating why lasers are necessary. Finally, experimental results are presented which describe the surface chemistry of coal/resin flotation systems and the adsorption phenomena/double-bond reactivity of unsaturated fatty acids at semisoluble salt mineral surfaces.

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Chen, Wei R., Baha Jassemnejad, Jason Crull, Edward T. Knobbe y Robert E. Nordquist. "Detection and characterization of chemical-induced abnormal tissue and rat tumors at different stages using fluorescence spectroscopy". En Photonics West '96, editado por Robert R. Alfano y Abraham Katzir. SPIE, 1996. http://dx.doi.org/10.1117/12.237570.

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Chang, Jin, Bingbo Zhang, Dena Li, Guiping Ma, Weicai Wang y Qi Zhang. "Preparation and Characterization of Tricolor CdSe-Tagged Microbeads for Bio-Detection". En 2007 First International Conference on Integration and Commercialization of Micro and Nanosystems. ASMEDC, 2007. http://dx.doi.org/10.1115/mnc2007-21138.

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Tricolor microbeads for biological assay have been prepared by embedding three quantum dots (cadmium selenide semiconductor nanocrystals) of different size into carboxyl-functionalized polystyrene (PS-COOH) microbeads. These efforts can render CdSe nanocrystals water-solubility, chemical stability and good photostability. The results indicate that QDs-tagged microbeads are highly uniform, reproducible and strong in fluorescence emission. Based on the properties it possesses, QDs-tagged microbead may have great potential for bio-detection.

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Andrade, Karine N. de, Amanda R. P. Costa, Rodolfo I. Teixeira, Micaeli L. da S. Moreira, José Walkimar M. Carneiro, Nanci C. L. Garden, Fernanda da C. S. Boechat, Maria Cecília B. V. de Souza, Pedro N. Batalha y Rodolfo G. Fiorot. "Photophysical characterization of 3-acyl-4-quinolones". En VIII Simpósio de Estrutura Eletrônica e Dinâmica Molecular. Universidade de Brasília, 2020. http://dx.doi.org/10.21826/viiiseedmol202006.

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4-quinolones derivatives can present fluorescent properties, depending on their substituents and on the chemical environment (e.g., acidic medium), allowing their application as ion sensors. We theoretically evaluated the photophysical properties of previously synthesized 3-acyl-4-quinolones to verify how different substituents (R1=H, NH2 and R2 = OEt, OH, NHPh) affect their absorption profiles and the emission profile of a reference compound, PB3. All DFT and TD-DFT calculations were performed at B3LYP-D3/6-311++G(d,p) level and continuum polarization model for simulated acetonitrile as solvent. For PB2 (R1 = H, R2 = OEt), we observed hypsochromic shift compared to PB3 due to the increase of the gap between HOMO/LUMO (absence of electron-donating group), in accordance with experimental data. For R1=NH2 and R2=OH, NHPh (PB6 and PB10, respectively), the gap between HOMO/LUMO increases, resulting in a soft bathochromic shift for the simulated absorption spectra. In addition, we evaluated the effect of acid addition on the absorption and emission profile of PB3 and the results were compared with experimental data. Our thermodynamic results suggest that protonation occurs on the endocyclic carbonyl of the quinolone moiety, probably due to an increased aromatic character, as suggested by our NICS calculations. Finally, we associate the increase of the fluorescence in the acidic medium to the establishment of an intramolecular hydrogen bond and, thus, increased rigidity.

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Sears, Trevor J. "High-resolution spectroscopy of chemical intermediates". En OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/oam.1990.wc1.

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Infrared and UV-vis laser spectroscopy has been used to study a number of small free radicals, with an emphasis on those exhibiting large amplitude vibrational motion or a strong breakdown of the Born-Oppenheimer approximation. Recently, we have detected gas phase infrared absorption spectra of the ethyl (C2H5) and carboxyl (HOCO) radicals for the first time. The C2H5 spectrum shows clear evidence for nearly free rotation of the CH2 radical center relative to the CH3 end of the molecule, while the HOCO spectrum appears to be somewhat simpler although analysis is far from complete. Following spectroscopic characterization of these species, infrared absorption will offer a precise and sensitive method for monitoring the radical concentrations on a state-by-state basis. Other species including NCS, C3, and NCO have been studied by laser induced fluorescence in a supersonic free jet expansion. Highly excited vibrational states have been accessed by optical double resonance (stimulated emission pumping) and the experimental data demand extensions of the standard effective Hamiltonian treatments describing the energy levels of these and similar species as increasing amounts of energy are placed in the internal modes.

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Bardhan, Pritam y Manabendra Mandal. "Rhodotorula mucilaginosa R2: A potent oleaginous yeast isolated from traditional fermented food, as a promising platform for the production of lipid-based biofuels, bioactive compounds and other value added products". En 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/qbyp3823.

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Oleaginous yeasts may provide an alternative platform for the sustainable production of microbial lipids-derived biodiesel and other health promoting bioactive metabolites such as natural pigments. In this regard, traditional fermented foods are unique and untapped habitats for the isolation and characterization of oleaginous yeasts with beneficial properties. In this study, we analysed the yeast diversity from selected traditional fermented foods of Manipur and Mizoram, India and studied their oleaginous attributes for biodiesel production. 14 potential oleaginous yeasts were isolated using culture-dependent techniques. The isolates were identified by 5.8S internal transcribed spacer (ITS) rRNA gene sequencing. Intracellular triacylglycerides (TAG) accumulation by yeast cells were confirmed by Nile red fluorescence microscopy. Fatty acid methyl esters (FAME) profile of the yeast strains were analysed by GC-MS. The identified yeast isolates belonged to seven different genera viz. Rhodotorula, Pichia, Candida, Saturnispora, Wickerhamomyces, Zygoascus and Saccharomyces. Rhodotorula mucilaginosa R2 exhibited the maximum lipid content (% lipid/g dry cell weight) of (21.63 %) after 96 h of growth in nitrogen-limited medium. R. mucilaginosa R2 single cell oil (RMSCO) was transesterified into biodiesel with a conversion efficiency of 96.6 % using a heterogeneous potassium hydroxide catalyst (K-RAC) supported on R. mucilaginosa R2 deoiled cake activated carbon. The physico-chemical properties of the biodiesel derived from R. mucilaginosa R2 single cell oil were within the limits of ASTM and EN standards. FAME analysis of the transesterified lipid extract suggested the potential use of yeast derived oil as an alternative to vegetable oil for biodiesel production. Furthermore, carotenoids obtained from the pink yeast R. mucilaginosa R2 was composed of torularhodin, torulene and Î²-carotene and exhibited strong antioxidant activity. Keywords: Oleaginous yeast, Triacylglycerides, Fermented food, Rhodotorula mucilaginosa

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Informes sobre el tema "Physico-chemical characterization by fluorescence"

VerMeulen, Holly, Jay Clausen, Ashley Mossell, Michael Morgan, Komi Messan y Samuel Beal. Application of laser induced breakdown spectroscopy (LIBS) for environmental, chemical, and biological sensing. Engineer Research and Development Center (U.S.), junio de 2021. http://dx.doi.org/10.21079/11681/40986.

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The Army is interested in sensors capable of characterizing/monitoring the environment (battlefield or military training ranges) at proximal distances. Recently, we evaluated laser induced breakdown spectroscopy (LIBS) systems (hand-held, proximal, and bench top) for the characterization of metals (antimony, copper, lead, tungsten, and zinc) in soils obtained from military training ranges. We then compared the results to findings obtained with standard field and laboratory instrumentation for metals analysis -X-ray Fluorescence (XRF) and Inductively Couple Plasma- Optical Emission Spectroscopy (ICP-OES).

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Clausen, Jay, Richard Hark, Russ Harmon, John Plumer, Samuel Beal y Meghan Bishop. A comparison of handheld field chemical sensors for soil characterization with a focus on LIBS. Engineer Research and Development Center (U.S.), febrero de 2022. http://dx.doi.org/10.21079/11681/43282.

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Commercially available handheld chemical analyzers for forensic applications have been available for over a decade. Portable systems from multiple vendors can perform X-ray fluorescence (XRF) spectroscopy, Raman spectroscopy, Fourier transform infrared(FTIR) spectroscopy, and recently laser-induced breakdown spectroscopy (LIBS). Together, we have been exploring the development and potential applications of a multisensor system consisting of XRF, Raman, and LIBS for environmental characterization with a focus on soils from military ranges. Handheld sensors offer the potential to substantially increase sample throughput through the elimination of transport of samples back to the laboratory and labor-intensive sample preparation procedures. Further, these technologies have the capability for extremely rapid analysis, on the order of tens of seconds or less. We have compared and evaluated results from the analysis of several hundred soil samples using conventional laboratory bench top inductively coupled plasma atomic emission spectroscopy (ICP-AES) for metals evaluation and high-performance liquid chromatography (HPLC) and Raman spectroscopy for detection and characterization of energetic materials against handheld XRF, LIBS, and Raman analyzers. The soil samples contained antimony, copper, lead, tungsten, and zinc as well as energetic compounds such as 2,4,6-trinitrotoluene(TNT), hexahydro-1,3,5-triazine (RDX), nitroglycerine (NG), and dinitrotoluene isomers (DNT). Precision, accuracy, and sensitivity of the handheld field sensor technologies were compared against conventional laboratory instrumentation to determine their suitability for field characterization leading to decisional outcomes.

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Cheng, Meng-Dawn. PHYSICO-CHEMICAL DYNAMICS OF NANOPARTICLE FORMATION DURING LASER DECONTAMINATION AND CHARACTERIZATION. Office of Scientific and Technical Information (OSTI), junio de 2002. http://dx.doi.org/10.2172/835402.

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Baral, Aniruddha, Jeffery Roesler y Junryu Fu. Early-age Properties of High-volume Fly Ash Concrete Mixes for Pavement: Volume 2. Illinois Center for Transportation, septiembre de 2021. http://dx.doi.org/10.36501/0197-9191/21-031.

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High-volume fly ash concrete (HVFAC) is more cost-efficient, sustainable, and durable than conventional concrete. This report presents a state-of-the-art review of HVFAC properties and different fly ash characterization methods. The main challenges identified for HVFAC for pavements are its early-age properties such as air entrainment, setting time, and strength gain, which are the focus of this research. Five fly ash sources in Illinois have been repeatedly characterized through x-ray diffraction, x-ray fluorescence, and laser diffraction over time. The fly ash oxide compositions from the same source but different quarterly samples were overall consistent with most variations observed in SO3 and MgO content. The minerals present in various fly ash sources were similar over multiple quarters, with the mineral content varying. The types of carbon present in the fly ash were also characterized through x-ray photoelectron spectroscopy, loss on ignition, and foam index tests. A new computer vision–based digital foam index test was developed to automatically capture and quantify a video of the foam layer for better operator and laboratory reliability. The heat of hydration and setting times of HVFAC mixes for different cement and fly ash sources as well as chemical admixtures were investigated using an isothermal calorimeter. Class C HVFAC mixes had a higher sulfate imbalance than Class F mixes. The addition of chemical admixtures (both PCE- and lignosulfonate-based) delayed the hydration, with the delay higher for the PCE-based admixture. Both micro- and nano-limestone replacement were successful in accelerating the setting times, with nano-limestone being more effective than micro-limestone. A field test section constructed of HVFAC showed the feasibility and importance of using the noncontact ultrasound device to measure the final setting time as well as determine the saw-cutting time. Moreover, field implementation of the maturity method based on wireless thermal sensors demonstrated its viability for early opening strength, and only a few sensors with pavement depth are needed to estimate the field maturity.

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Zdanowicz, C., D. Kliza, D. Paktunc y G. F. Bonham-Carter. Physico-chemical characterization of airborne particulate impurities deposited in snow around a copper smelter, Rouyn-Noranda, Quebec. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2005. http://dx.doi.org/10.4095/221138.

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Asenath-Smith, Emily, Emma Ambrogi, Lee Moores, Stephen Newman y Jonathon Brame. Leveraging chemical actinometry and optical radiometry to reduce uncertainty in photochemical research. Engineer Research and Development Center (U.S.), septiembre de 2021. http://dx.doi.org/10.21079/11681/42080.

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Subtle aspects of illumination sources and their characterization methods can introduce significant uncertainty into the data gathered from light-activated experiments, limiting their reproducibility and technology transition. Degradation kinetics of methyl orange (MO) and carbamazepine (CM) under illumination with TiO₂ were used as a case study for investigating the role of incident photon flux on photocatalytic degradation rates. Valerophenone and ferrioxalate actinometry were paired with optical radiometry in three different illumination systems: xenon arc (XE), tungsten halogen (W-H), and UV fluorescent (UV-F). Degradation rate constants for MO and CM varied similarly among the three light systems as k W-H < kiv-F < kXE, implying the same relative photon flux emission by each light. However, the apparent relative photon flux emitted by the different lights varied depending on the light characterization method. This discrepancy is shown to be caused by the spectral distribution present in light emission profiles, as well as absorption behavior of chemical actinometers and optical sensors. Data and calculations for the determination of photon flux from chemical and calibrated optical light characterization is presented, allowing us to interpret photo-degradation rate constants as a function of incident photon flux. This approach enabled the derivation of a calibrated ‘rate-flux’ metric for evaluating and translating data from photocatalysis studies.

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Tracy, Noel A. Nondestructive Evaluation (NDE) Exploratory Development for Air Force Systems. Delivery Order 0001: Quick Reaction NDE and Characterization--Effects of Chemical Effects of Chemical Etching after Pre-Inspection Mechanical Cleaning on Fluorescent Penetrant Indications of Fatigue Cracks. Fort Belvoir, VA: Defense Technical Information Center, agosto de 2011. http://dx.doi.org/10.21236/ada550862.

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Steffens, John C. y Eithan Harel. Polyphenol Oxidases- Expression, Assembly and Function. United States Department of Agriculture, enero de 1995. http://dx.doi.org/10.32747/1995.7571358.bard.

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Polyphenol oxidases (PPOs) participate in the preparation of many plant products on the one hand and cause considerable losses during processing of plant products on the other hand. However, the physiological functions of plant PPO were still a subject of controversy at the onset of the project. Preliminary observations that suggested involvement of PPOs in resistance to herbivores and pathogens held great promise for application in agriculture but required elucidation of PPO's function if modulation of PPO expression is to be considered for improving plant protection or storage and processing of plant products. Suggestions on a possible role of PPO in various aspects of chloroplast metabolism were also relevant in this context. The characterization of plant PPO genes opened a way for achieving these goals. We reasoned that "understanding PPO targeting and routing, designing ways to manipulate its expression and assessing the effects of such modifications will enable determination of the true properties of the enzyme and open the way for controlling its activity". The objective of the project was to "obtain an insight into the function and biological significance of PPOs" by examining possible function(s) of PPO in photosynthesis and plant-pest interactions using transgenic tomato plants; extending our understanding of PPO routing and assembly and the mechanism of its thylakoid translocation; preparing recombinant PPOs for use in import studies, determination of the genuine properties of PPOs and understanding its assembly and determining the effect of PPO's absence on chloroplast performance. Results obtained during work on the project made it necessary to abandon some minor objectives and devote the effort to more promising topics. Such changes are mentioned in the 'Body of the report' which is arranged according to the objectives of the original proposal. The complex expression pattern of tomato PPO gene family was determined. Individual members of the family are differentially expressed in various parts of the plant and subjected to developmentally regulated turnover. Some members are differentially regulated also by pathogens, wounding and chemical wound signals. Wounding systemically induces PPO activity and level in potato. Only tissues that are developmentally competent to express PPO are capable of responding to the systemic wounding signal by increased accumulation of PPO mRNA. Down regulation of PPO genes causes hyper susceptibility to leaf pathogens in tomato while over expression regulation of PPO expression in tomato plants is their apparent increased tolerance to drought. Both the enhanced disease resistance conferred by PPO over expression and the increased stress tolerance due to down regulation can be used in the engineering of improved crop plants. Photosynthesis rate and variable fluorescence measurements in wild type, and PPO-null and over expressing transgenic tomato lines suggest that PPO does not enable plants to cope better with stressful high light intensities or reactive oxygen species. Rather high levels of the enzyme aggravate the damage caused under such conditions. Our work suggests that PPO's primary role is in defending plants against pathogens and herbivores. Jasmonate and ethylene, and apparently also salicylate, signals involved in responses to wounding and defense against herbivores and pathogens, enhance markedly and specifically the competence of chloroplasts to import and process pPPO. The interaction of the precursor with thylakoid membranes is primarily affected. The routing of PPO shows other unusual properties: stromal processing occurs in two sites, resulting in intermediates that are translocated across thylakoids by two different mechanisms - a DpH- and a Sec-dependent one. It is suggested that the dual pattern of processing and routing constitutes a'fail safe' mechanism, reflecting the need for a rapid and flexible response to defense challenges. Many of the observations described above should be taken into consideration when manipulation of PPO expression is contemplated for use in crop improvement.

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Perk, Simon, Egbert Mundt, Alexander Panshin, Irit Davidson, Irina Shkoda, Ameera AlTori y Maricarmen Garcia. Characterization and Control Strategies of Low Pathogenic Avian Influenza Virus H9N2. United States Department of Agriculture, noviembre de 2012. http://dx.doi.org/10.32747/2012.7697117.bard.

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The avian influenza virus, subtype H9N2 subtype, defined as having a low pathogenicity, causes extensive economical losses in commercial flocks, probably due to management and synergism with other pathogens. AIV H9N2 was first identified in Israel in the year 2000, and since then it became endemic and widespread in Israel. Control by vaccination of commercial flocks with an inactivated vaccine has been introduced since 2007. In face of the continuous H9N2 outbreaks, and the application of the vaccination policy, we aimed in the present study to provide a method of differentiating naturally infected from vaccinated animals (DIVA). The aim of the assay would be detect only antibodies created by a de-novo infection, since the inactivated vaccine virus is not reproducing, and might provide a simple tool for mass detection of novel infections of commercial flocks. To fulfill the overall aim, the project was designed to include four operational objectives: 1. Evaluation of the genetic evolution of AIV in Israel; 2. Assessment of the diagnostic value of an NS1 ELISA; 3. NS1 ELISA as evaluation criteria for measuring the efficacy of vaccination against H9N2 AIV; 4. Development of an AIV H9 subtype specific ELISA systems. Major conclusion and implications drawn from the project were: 1. A continuous genetic change occurred in the collection of H9N2 isolates, and new introductions were identified. It was shown thatthe differences between the HA proteins of viruses used for vaccine productionand local fieldisolatesincreasedin parallelwith the durationand intensity ofvaccine use, therefore, developing a differential assay for the vaccine and the wild type viruses was the project main aim. 2. To assess the diagnostic value of an NS1 ELISA we first performed experimental infection trials using representative viruses of all introductions, and used the sera and recombinant NS1 antigens of the same viruses in homologous and heterologous NS1 ELISA combination. The NS1 ELISA was evidently reactive in all combinations, and did not discriminate significantly between different groups. 3. However, several major drawbacks of the NS1 ELISA were recognized: a) The evaluation of the vaccination effect in challenged birds, showed that the level of the NS1 antibodies dropped due to the vaccination-dependent virus level drop; b) the applicability of the NS1-ELISA was verified on sera of commercial flocks and found to be unusable due to physico-chemical composition of the sera and the recombinant antigen, c) commercial sera showed non-reactivity that might be caused by many factors, including vaccination, uncertainty regarding the infection time, and possibly low antigen avidity, d) NS1 elevated antibody levels for less than 2 months in SPF chicks. Due to the above mentioned reasons we do not recommend the application of the DIVA NS1 ELISA assay for monitoring and differentiation AIV H9N2 naturally-infected from vaccinated commercial birds.

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