Bibliografías temáticas / Phosphene

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Literatura académica sobre el tema "Phosphene"

Autor: Grafiati
Publicado: 11 de marzo de 2023

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Artículos de revistas sobre el tema "Phosphene"

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Kvašňák, E., M. Orendáčová y J. Vránová. "Phosphene Attributes Depend on Frequency and Intensity of Retinal tACS". Physiological Research 71, n.º 4 (31 de agosto de 2022): 561–71. http://dx.doi.org/10.33549/physiolres.934887.

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Phosphene is the experience of light without natural visual stimulation. It can be induced by electrical stimulation of the retina, optic nerve or cortex. Induction of phosphenes can be potentially used in assistive devices for the blind. Analysis of phosphene might be beneficial for practical reasons such as adjustment of transcranial alternating current stimulation (tACS) frequency and intensity to eliminate phosphene perception (e.g., tACS studies using verum tACS group and sham group) or, on the contrary, to maximize perception of phosphenes in order to be more able to study their dynamics. In this study, subjective reports of 50 healthy subjects exposed to different intensities of retinal tACS at 4 different frequencies (6, 10, 20 and 40 Hz) were analyzed. The effectiveness of different tACS frequencies in inducing phosphenes was at least 92 %. Subject reported 41 different phosphene types; the most common were light flashes and light circles. Changing the intensity of stimulation often induced a change in phosphene attributes. Up to nine phosphene attributes changed when the tACS intensity was changed. Significant positive correlation was observed between number of a different phosphene types and tACS frequency. Based on these findings, it can be concluded that tACS is effective in eliciting phosphenes whose type and attributes change depending on the frequency and intensity of tACS. The presented results open new questions for future research.
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Indahlastari, Aprinda, Aditya K. Kasinadhuni, Christopher Saar, Kevin Castellano, Bakir Mousa, Munish Chauhan, Thomas H. Mareci y Rosalind J. Sadleir. "Methods to Compare Predicted and Observed Phosphene Experience in tACS Subjects". Neural Plasticity 2018 (6 de diciembre de 2018): 1–10. http://dx.doi.org/10.1155/2018/8525706.

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Background. Phosphene generation is an objective physical measure of potential transcranial alternating current stimulation (tACS) biological side effects. Interpretations from phosphene analysis can serve as a first step in understanding underlying mechanisms of tACS in healthy human subjects and assist validation of computational models. Objective/Hypothesis. This preliminary study introduces and tests methods to analyze predicted phosphene occurrence using computational head models constructed from tACS recipients against verbal testimonies of phosphene sensations. Predicted current densities in the eyes and the occipital lobe were also verified against previously published threshold values for phosphenes. Methods. Six healthy subjects underwent 10 Hz tACS while being imaged in an MRI scanner. Two different electrode montages, T7-T8 and Fpz-Oz, were used. Subject ratings of phosphene experience were collected during tACS and compared against current density distributions predicted in eye and occipital lobe regions of interest (ROIs) determined for each subject. Calculated median current densities in each ROI were compared to minimum thresholds for phosphene generation. Main Results. All subjects reported phosphenes, and predicted median current densities in ROIs exceeded minimum thresholds for phosphenes found in the literature. Higher current densities in the eyes were consistently associated with decreased phosphene generation for the Fpz-Oz montage. There was an overall positive association between phosphene perceptions and current densities in the occipital lobe. Conclusions. These methods may have promise for predicting phosphene generation using data collected during in-scanner tACS sessions and may enable better understanding of phosphene origin. Additional empirical data in a larger cohort is required to fully test the robustness of the proposed methods. Future studies should include additional montages that could dissociate retinal and occipital stimulation.
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Et.al, Manami, K. "Investigation of Electrical Interference towards Phosphene-Based Walking Support System". Turkish Journal of Computer and Mathematics Education (TURCOMAT) 12, n.º 3 (10 de abril de 2021): 2178–83. http://dx.doi.org/10.17762/turcomat.v12i3.1164.

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A walking support system with phosphenes for blind people has been investigated. Phosphene is a phenomenon where a flash of light is recognized in the brain by giving an electrical stimulus to human’s visual pathway. Phosphenes can be perceived even if their eyes are closed or they are blind. It has been clarified that phosphenes can be induced to several directions if electrodes placements are precisely selected. When phosphenes are presented to two directions for recognizing two obstacles, two pairs of electrodes must be applied. In such a case, however, the electrical interference occurs due to the short distance between electrodes. In the practical use of the phosphene-based walking support system, the avoidance of electrical interference is significant in order to present the phosphenes precisely. Therefore, in this paper, we first practically investigate the electrical interference by considering the difference in phosphene induction generated by a single pair of electrodes and by two pairs of electrodes. Then, the solutions to avoid the electrical interference are discussed.
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Massumi, Brian. "Purple phosphene". Angelaki 4, n.º 3 (diciembre de 1999): 219–20. http://dx.doi.org/10.1080/09697259908572072.

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Kanamaru, Manami, Phan Xuan Tan y Eiji Kamioka. "Simulation-Based Designing of Suitable Stimulation Factors for Presenting Two Phosphenes Simultaneously to Lower Side of Field of View". Bioengineering 9, n.º 12 (2 de diciembre de 2022): 752. http://dx.doi.org/10.3390/bioengineering9120752.

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Using a phosphene has been discussed as a means of informing the visually impaired of the position of an obstacle. Obstacles underfoot have a risk, so it is necessary to inform the visually impaired. A previous study clarified a method of presenting phosphene in three directions in the lower vision; however, the simultaneous presentation of these phosphenes has not been discussed. Another study discussing the effect of electrical interference when stimulating the eyeball with multiple electrodes indicated that it is important to select appropriate stimulation factors to avoid this effect. However, when the stimulation electrodes are arranged remarkably close, there is a high possibility that the stimulus factor presented in the previous study will not apply. In this study, a method for simultaneously presenting phosphenes in the lower vision is presented. The electrode arrangements reported in the previous study to present phosphene in the lower field of vision are used, and the difficulty in the simultaneous presentation of multiple phosphenes in the lower vision is the focus. In this paper, the method of designing the stimulation factors is discussed numerically when the electrodes are arranged remarkably close. As a result, it is shown that stimulation factors different from the previous research were appropriate depending on the distance between the electrodes.
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Avraham, David y Yitzhak Yitzhaky. "Effects of Depth-Based Object Isolation in Simulated Retinal Prosthetic Vision". Symmetry 13, n.º 10 (22 de septiembre de 2021): 1763. http://dx.doi.org/10.3390/sym13101763.

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Visual retinal prostheses aim to restore vision for blind individuals who suffer from outer retinal degenerative diseases such as retinitis pigmentosa and age-related macular degeneration. Perception through retinal prostheses is very limited, but it can be improved by applying object isolation. We used an object isolation algorithm based on integral imaging to isolate objects of interest according to their depth from the camera and applied image processing manipulation to the isolated-object images. Subsequently, we applied a spatial prosthetic vision simulation that converted the isolated-object images to phosphene images. We compared the phosphene images for two types of input images, the original image (before applying object isolation), and the isolated-object image to illustrate the effects of object isolation on simulated prosthetic vision without and with multiple spatial variations of phosphenes, such as size and shape variations, spatial shifts, and dropout rate. The results show an improvement in the perceived shape, contrast, and dynamic range (number of gray levels) of objects in the phosphene image.
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Steidley, K. David. "The radiation phosphene". Vision Research 30, n.º 8 (enero de 1990): 1139–43. http://dx.doi.org/10.1016/0042-6989(90)90171-g.

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Nissi, Janita y Ilkka Laakso. "Magneto- and electrophosphene thresholds in the retina: a dosimetry modeling study". Physics in Medicine & Biology 67, n.º 1 (7 de enero de 2022): 015001. http://dx.doi.org/10.1088/1361-6560/ac46df.

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Abstract Objective. Sensations of flickering light produced by time-varying magnetic fields or electric currents are called magneto- or electrophosphenes. Phosphene thresholds have been used in international guidelines and standards as an estimate of the thresholds of exposure that produce effects in the central nervous system (CNS). However, the estimated threshold values have a large range of uncertainty. Approach. Phosphene thresholds were approximated by simulating five phosphene threshold experiments. Retinal electric fields and currents induced by electric and magnetic stimulation were calculated using the finite element method and 14 anatomically realistic computational models of human heads. Main results. The radial component of retinal current density was determined to be in the range of 6.0–20.6 mA m−2. This study produces more accurate estimates for threshold current density in the retina using detailed anatomical models and the estimates had a reduced range of uncertainty compared to earlier studies. Significance. The results are useful for studying the mechanisms of retinal phosphenes and for the development of exposure limits for the CNS.
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Kanamaru, Manami, Phan Xuan Tan y Eiji Kamioka. "Simulation-Based Clarification of Appropriate Factors for Presenting Phosphene in Two Directions Avoiding Electrical Interference". Bioengineering 8, n.º 8 (5 de agosto de 2021): 111. http://dx.doi.org/10.3390/bioengineering8080111.

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Walking support systems are essential for blind people. In this study, the presentation of phosphene position is focused on as a method to detect obstacles for blind people. When the phosphene is used in a walking support system, it is necessary to accurately present the phosphene in at least three directions of the visual field. Controlling the presentation of phosphene position has been reported in several previous studies. However, methodologies to present phosphene in multiple directions without any electric interference have not as yet been investigated. In this study, therefore, appropriate stimulation factors are clarified by the simulation of electric field on the eyeball surface which is strongly related to the presentation of phosphene position in the visual field. As a result of the simulation, it was revealed that the distance of each electrode does not give a significant effect to the eyeball surface. However, the phase of alternating current significantly changed the electric field on the eyeball surface. From investigation of the simulation results, it was clarified that the transition of the electric field on the eyeball surface can be controlled using anti-phase stimulation. In addition, the methodology to present the phosphene at least in two directions was verified.
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Niketeghad, Soroush, Abirami Muralidharan, Uday Patel, Jessy Dorn, Robert Greenberg y Nader Pouratian. "150 Effect of Stimulation Parameters on Visual Percepts Elicited by Stimulation of a Visual Cortical Prosthesis for the Blind". Neurosurgery 64, CN_suppl_1 (24 de agosto de 2017): 236. http://dx.doi.org/10.1093/neuros/nyx417.150.

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Abstract INTRODUCTION Stimulation of human visual cortex is known to elicit visual percepts (phosphenes) which makes it a suitable candidate for generating artificial vision for blind. Although there have been a few attempts to build visual cortical prostheses, a greater understanding of the physiology of stimulation is required to generate useful perceptions. This study aims to characterize the phosphenes elicited by a neurostimulation device and explore the effects of stimulation parameters (amplitude, frequency, pulse-width and burst duration) on the quality of these percepts. METHODS A 30-year-old volunteer with an 8-year history of bare light perception secondary to Voght-Koaynagi-Harada Syndrome participated in this study. Two parallel cortical strip leads (each with four contacts) were implanted over the right medial occipital lobe. Phosphene characteristics were assessed postoperatively using subject's drawings of on a touch screen as well as subjective description of the percepts intensity and color. The stimulus parameters for eliciting a well-defined phosphene were obtained by varying the stimulus parameters for each contact at the beginning of each session during the eight months' period of the study. RESULTS >Stimulation of each of the eight contacts elicited phosphenes with a consistent shape and location in the visual field. The stimulus parameters for generating a well-defined phosphene were stable for six contacts and had to be adjusted for two over the period of the study. Increasing the amplitude and frequency resulted in more intense perceptions and the subject indicated seeing colored phosphenes for certain amplitudes. Simultaneous stimulation of multiple contacts was perceived as a summation of percepts elicited by stimulating the contacts individually. Sequential stimulation of two contacts generated two phosphenes and the subject was able to identify them in order. CONCLUSION Visual cortical prostheses are feasible candidates for creating artificial sight due to reproducibility of the perceptions and consistency of the stimulation parameters required to generate basic visual perceptions.
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Tesis sobre el tema "Phosphene"

1

Deerenberg, Sirik. "Stereogenic phosphorus containing phosphine-phosphite ligands in asymmetric catalysis". [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2000. http://dare.uva.nl/document/57171.

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Passays, Johan. "Nouveaux ligands mixtes de type phosphore / carbène N-hétérocyclique : synthèse et applications en catalyse asymétrique". Thesis, Rouen, INSA, 2011. http://www.theses.fr/2011ISAM0008.

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Une méthode simple et efficace a été développée pour la préparation de ligands bifonctionnels associant les motifs phosphine ou phosphite d'une part, et carbène Nhétérocyclique(NHC) ou imidazolium d'autre part. Dans un premier temps, une série de ligands diphénylphosphine-carbène chiraux portant un centre stéréogène en a de la phosphinea été développée à partir b-hydroxyesters. Une famille de ligands a ainsi été développée afin d'évaluer l'influence de l'encombrement stérique de différents groupements alkyles en a de la phosphine et de la nature des groupements aromatiques portés sur l'imidazole sur leur activité catalytique. L’étude s’est ensuite étendue à la synthèse de ligands de type dialkylphosphine carbène et phosphite-carbène. Ces différents ligands ont été complexés avec des métaux tels que l’iridium ou le rhodium de manière à en étudier l’activité en hydrogénation asymétrique
A straightforward method for the preparation of new bidentate ligands containing aphosphine or a phosphite and a carbene function was developed. Different phosphorus-imidazolium compounds were prepared according to this method. First, diphenylphosphine-NHC ligands featuring a stereogenic center a to the phosphine were synthesized from b-hydroxyesters. This strategy was then extended to the preparation of phosphite-imidazoliumand dialkylphosphine-imidazolium compounds. Complexation of these phosphorus-NHCligands with different metals like Ir or Rh was performed in order to study there catalytic properties in asymmetric hydrogenation
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3

Phung, Quang Linh. "Synthèse de ligands chiraux de type phosphine-phosphite et phosphine-carbène N-hétérocyclique pour la catalyse asymétrique". Rouen, 2005. http://www.theses.fr/2005ROUES033.

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La catalyse organométallique est une méthode de choix pour la synthèse de composés chiraux. Afin d'atteindre une selectivité et efficacité élevées en catalyse asymétrique, plusieurs paramètres réactionnels doivent être optimisés, parmi lesquels le choix et la structure du ligand sont sans doute les points les plus importants. Nous avons développé deux familles de ligands bidentates de type phosphine-phosphite et phosphine-carbène N-hétérocyclique. Ces deux séries de ligands possèdent une caractéristique structurale commune, à savoir un centre asymétrique adjacent à la phosphine. Cette proximité du centre stéréogène et de l'atome de phosphore pourrait avoir un effet positif sur l'énantiodiscrimination. Les ligands phosphine-phosphites ont été testés en hydrogénation (ee jusqu'à 84%) et hydroformylation (pas d'induction asymétrique) asymétriques catalysées par le rhodium. Les ligands phosphine-carbènes N-hétérocycliques ont été testés en hydrogénation et hydrosilylation asymétriques catalysées à l'iridium (pas d'induction asymétrique), et avec des résultats prometteurs dans le couplage de Suzuki-Miyaura
Catalytic asymmetric synthesis using organometallic reagents has become one of the most active areas of research in modern organic synthesis. To achieve the highest levels of reactivity and selectivity in catalytic enantioselective reactions, several reactions parameters must be optimized. Among them, the selection and design of the chiral ligand is perhaps the most crucial step. We have developed two families of bidentate ligands : phosphine-phosphite and phosphine N-heterocyclic carbene. These two series of ligands have a chiral center to the α-position next to the phosphine moiety. This stereogenic α-position could be of great importance since the phosphorus atom is directly associated with the transition metal in the asymmetric reaction. Phosphine-phosphite ligands were tested in the Rh-catayzed asymmetric hydrogenation (ee up to 84%) and hydroformylation (no asymmetric induction). Phosphine N-heterocyclic carbene ligands were tested in the Ir-catalyzed asymmetric hydrogenation and hydrosilylation (no asymmetric induction), and with promising results in the Suzuki-Miyaura cross-coupling reaction
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Klüpfel, Bernd. "P-chirale funktionelle Phosphane durch Hydrophosphinierung mit kationischen Phosphan-Eisenkomplexen". [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=966083458.

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Javierre, Guilhem. "Understand the inversion mechanism of P-stereogenic compound using kinetic studies and in silico modeling". Thesis, Ecole centrale de Marseille, 2018. http://www.theses.fr/2018ECDM0001/document.

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La thèse consiste en l'étude de la racémisation d'hydrogéno-phénylphosphinates d'alkyle, des molécules centrées sur un phosphore stéréogénique. Pour cela, nous avons synthétisé les composés d'intérêt puis étudié leur cinétique de racémisation en utilisant l'HPLC chirale et la RMN du phosphore. La première étude théorique (SMD//M06-2X/6-31++G**) sur l’énantiomérisation d’un phosphinate d’alkyle après une SN2 par un alcool a montré comme mécanisme le plus favorable une syn-addition de l’alcool sur la double liaison P=O du phosphinate à l’opposé du groupement alkoxy. Les études cinétiques d’inversion du phosphinate d’éthyle dans l’éthanol à reflux ont montré une barrière de 135 kJ.mol-1 en moyenne, en excellent accord avec ce modèle (136 kJ.mol-1). L’ajout de base lors de l’étude cinétique ont montré une accélération de l’inversion avec une barrière maximum mesurée à 121,5 kJ.mol-1 montrant un effet de catalyse basique. Les modèles cinétiques et théoriques réalisés à ce jour ont suggéré que la base activerait l’alcool pour faciliter son addition. Les premiers résultats sur l’influence du groupement alkyle ont montré une dépendance globale de l’inversion à la taille du groupement, mais certains modèles DFT, notamment avec l’adamantyle, n’étaient pas en accord avec cette hypothèse
This thesis is about the racemization of alkyl hydrogeno-phenylphosphinate, a molecule centered on a stereogenic phosphorus atom. We have synthetized compounds of interest, and studied their kinetic of racemization with chiral HPLC and phosphorus NMR. The first theoretical study (SMD//M06-2X/6-31++G**) about the enantiomerization of alkyl phosphinate after an SN2 with an alcohol have shown that the most favored mechanism was a syn-addition of the alcohol onto the double bond P=O on the opposite side of the alkoxy group. Kinetic studies with ethyl phosphinate in ethanol under reflux have shown an inversion barrier around 135 kJ.mol-1, in excellent agreement with this model (136 kJ.mol-1). The addition of a basic compound during kinetic measurements has shown a decreasing of the barrier to 121.5 kJ.mol-1, showing a catalytic effect. Kinetic and theoretical models have suggested that the mechanism would go through an activation of the alcohol by the basic compound which would facilitate its addition. The first tests about the nature of the alkyl group of phosphinate and alcohol have shown a general dependency of the barrier with the hindrance, but some DFT models, especially with adamantyl, have been in disagreement with this hypothesis
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Alcaraz, Gilles. "Espèces déficientes en électrons et cycles tendus alpha-phosphorés". Toulouse 3, 1995. http://www.theses.fr/1995TOU30126.

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Les -phosphinocarbenes et les -phosphinonitrenes sont des entites presentant un fort caractere nucleophile. En presence de boranes, la formation d'adduits de type carbene-acide de lewis et nitrene-acide de lewis a ete demontree sans ambiguite. La caracterisation par spectroscopie rmn d'un adduit phosphinocarbene-borane a pu etre realisee. Dans le second chapitre, une methode de synthese originale de phosphino-2h-azirines par cycloaddition (1+2) d'un phosphinosilylcarbene sur des nitriles est presentee. Les phosphino-2h-azirines se comportent soit comme des phosphines vraies soit comme des dipoles-1,4. Elles peuvent egalement par reaction d'extension de cycle conduirent a des 1,2#5-azaphosphetes. Dans le troisieme chapitre, la reactivite de la bromophenyldiazirine en presence de phosphines a ete etudiee. D'un point de vue mecanistique nous avons demontre que la premiere etape de l'attaque met en jeu une isodiazirine transitoire. D'un point de vue synthetique, le comportement de la bromophenyldiazirine comme pourvoyeur de fragment nc(ph)n+ a ete mis a profit pour engendrer toute une gamme d'especes polyphosphorees cationiques acycliques, cycliques et macrocycliques. En presence de stannylphosphine, l'obtention d'un heterocycle phosphore (le 1,3,2#5-diazaphosphete) demontre clairement l'enorme potentiel de la reaction mise en jeu
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Schmidt, Anette. "Phosphide und Phosphate des Cobalts Kristallisation, Thermodynamik, Strukturen und Farben /". [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=965185273.

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Harrison, Mark Anthony. "EXPOSURE TO PHOSPHINE GAS DURING APPLICATION OF MAGNESIUM PHOSPHIDE IN STORED PRODUCT WAREHOUSES". VCU Scholars Compass, 1990. http://scholarscompass.vcu.edu/etd/4909.

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The use of phosphine gas requires that respiratory protection be used if exposures exceed the OSHA permissible exposure limit. As with other chemical exposures limits many of the references used to establish occupational health guidelines date back to the 1930’s and 1940’s. This is quite common and is the case with phosphine gas. Initial planning for fumigations involving magnesium phosphide requires that a hazard assessment be performed. Expected worker exposures based on previous monitoring or test data was not readily available. Many current practices and procedures for fumigations are based on recommendations from applicators who used the product in the 1950’s and 60’s. Unfortunately, many of the recommendations were based on personal opinion and experience rather than actual exposure monitoring data. Not until the 1980's were comprehensive applicator exposure assessments being conducted for different tasks involving magnesium phosphide. As a result, it is necessary to generate current applicator exposure data and compare the data to current occupational exposure limits for phosphine gas.
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9

Tohme, Ayham. "Synthèse et étude de phosphines organométalliques électrocommutables pour la catalyse". Thesis, Rennes 1, 2014. http://www.theses.fr/2014REN1S012/document.

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Au cours de cette thèse, nous avons synthétisé et caractérisé de nouvelles phosphines possédant des groupements fonctionnels organométalliques rédox-actifs. En modifiant l'état rédox de ceux-ci, les propriétés électroniques de ces ''métalloligands'' devraient changer, induisant ainsi une modification de la densité électronique autour du métal auquel ils sont coordinés. Idéalement, cela devrait se traduire par un changement de l'activité catalytique du métal, si celui-ci intervient comme catalyseur dans une transformation catalytique. Nous avons tout d'abord étudié de ligands triarylphosphines fonctionnalisés par un ou trois groupements organofers. Après caractérisation de quatre métalloligands de ce type à l'état réduit et à l'état oxydé, leurs paramètres électroniques ont été évalués par deux méthodes expérimentales différentes. Finalement, les complexes Pd(II) correspondant aux métalloligands ont été synthétisés et testés en catalyse. Ensuite, nous nous sommes intéressés à la chimie de dérivés alkynyldiarylphosphines organométalliques. Ces complexes sont instables après oxydation, formant des complexes bis-acétylures Fe(II) dicationiques, qui ont pu être isolés et caractérisés. L'inhibition de la dimérisation a été possible par séquestration du doublet électronique du phosphore ou par apport de gêne stérique autour de celui-ci. Enfin, des pré-catalyseurs correspondant à ces métallophosphines ont été également synthétisés et étudiés. Ces complexes se sont révélés stables, après oxydation des ligands, et les performances de certains en catalyse ont été évaluées
During this work, we have synthesized and characterized new metalloligands bearing redox-active organometallic end-groups. Switching the redox state of the latter should modify the electronic properties of the studied metalloligands. Once these are complexed to a metal, this should induce a change of the metal’s electronic density, which results ideally in a change of its catalytic activity. First, we studied triarylphosphine ligands bearing one or three organoiron end-groups. Four of these metalloligands were fully characterized in both their reduced and oxidized states, and their electronic parameters were evaluated using two different experimental methods. Later on, corresponding Pd(II) complexes were also synthesized and their catalytic preformances were tested. In the second part of this work, organometallic Fe(II) alkynyldiarylphosphine derivatives were synthesized. Upon oxidation, the resulting species was found to be unstable, leading to the formation of dicationic bis-acetylide Fe(II) complexes, that were isolated and characterized. The dimerization process was inhibited either by sequestration of the electronic lone pair of the phosphorus atom, or by controlling the steric hindrance around that center. Finally, corresponding precatalysts were synthesized and, upon the oxidation of the metalloligands, they were found to be fairly stable compounds. Some of these complexes were also tested in a catalytic transformation
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Mocanu, Olivia. "Phosphole and phosphepine-based π-systems : synthesis, reactivity and physical properties". Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1S166.

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Ce manuscrit décrit la synthèse et les caractérisations physico-chimiques de nouveaux systèmes hétérocycliques π-conjugués contenant un atome de phosphore. Le chapitre d'introduction présente les différentes voies de synthèse du cycle phospholes pouvant être incorporé dans des systèmes π-conjugués. Le chapitre I décrit la synthèse et les propriétés physico-chimiques de dérivés du pyrène contenant soit un phosphole, soit un silole. La synthèse de ces nouvelles structures a été réalisée à l'aide de réactions métallo-catalysées. Deux types de régioisomères ont ainsi été synthétisés afin de déterminer l'impact de la nature de l'hétéroatome (P ou Si) sur leurs propriétés optiques et électrochimiques et sur l'organisation des molécules à l'état solide. Le chapitre II décrit la synthèse et les propriétés physico-chimiques de nouveaux complexes d'Ir(III) ortho-métallés contenant un ligand phosphole. La présence de deux centres stéréogènes induit la formation de diastéréoisomères, dont la formation peut être contrôlée par les conditions réactionnelles. De plus, les propriétés électroniques du ligand phosphole permettent de moduler à façon les propriétés redox et optiques du complexe. Le chapitre III se focalise sur l'utilisation de la phosphépine comme sous-unité pour la construction de nouveaux systèmes π-conjugués. Deux systèmes π-conjugués ont été synthétisés : un squelette de PAH contenant la phosphépine et les dithieno-phosphépines. Les propriétés optiques et redox de ces dérivés ont été étudiées et discutées dans le manuscrit
This manuscript describes the synthesis and characterisation of new heterocyclic π-conjugated systems built around the phosphorus atom. Firstly, an introduction to the phosphole chemistry (synthesis methods and integration into π-conjugated systems) is presented. The chapter I describes the synthesis and physico-chemical properties of pyrene functionalised either by a phosphole or silole ring. The synthesis of these new structures was achieved by using a transition-metal catalysis. Two types of regioisomers were synthesised in order to study the effect of the heteroatom (P or Si) on the optical and electrochemical properties together with the impact on the solid-state organisation. The chapter II describes the synthesis and the physical properties of the first phosphole-based Ir(III) ortho-metallated complexes. The presence of two stereogenic centres in the complex induced diastereoselectivity issues that could be solved by carefully choosing the reaction conditions. Furthermore, it was demonstrated that the nature of the ligands can tune the optical and the redox properties. The chapter III describes the use of P-containing seven-membered rings (phosphepines) for the development of new π-conjugated systems. Two original π-systems have been synthesised and studied: (i) phosphepine based PAH and (ii) dithieno-phosphepines. The optical and redox properties have been investigated and discussed in the manuscript
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Libros sobre el tema "Phosphene"

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executive, Health and safety. Fumigation using phosphine. London: H.M.S.O., 1986.

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Davis, B. E. Recovery of phosphate from Florida phosphate slimes. Pittsburgh, Pa: U.S. Dept. of the Interior, Bureau of Mines, 1987.

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Razzaque, Mohammed S., ed. Phosphate Metabolism. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-91623-7.

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Griffith, Edward J. Phosphate Fibers. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4899-1045-5.

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Bergeron, Pierre. Phosphènes célestes. Longueuil, Québec: Productions Imagie, 2009.

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International Program on Chemical Safety., International Labour Organisation, World Health Organization, United Nations Environment Programme y WHO Task Group on Environmental Health Criteria For Tricresyl Phosphate., eds. Tricresyl phosphate. Geneva: World Health Organization, 1990.

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Griffith, Edward J. Phosphate Fibers. Boston, MA: Springer US, 1995.

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Phosphate fibers. New York: Plenum Press, 1995.

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Great Britain. Ministry of Agriculture Fisheries and Food., ed. Phosphate fertilisers. Alnwick: Great Britain, 1987.

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N, Nikonov G. y Arbuzov Boris Aleksandrovich 1903-, eds. Funkt͡s︡ionalʹnozameshchennye fosfiny i ikh proizvodnye. Moskva: "Nauka", 1986.

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Capítulos de libros sobre el tema "Phosphene"

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Stronks, H. Christiaan y Gislin Dagnelie. "Phosphene Mapping Techniques for Visual Prostheses". En Visual Prosthetics, 367–83. Boston, MA: Springer US, 2011. http://dx.doi.org/10.1007/978-1-4419-0754-7_19.

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Evreinova, Tatiana G., Grigori Evreinov y Roope Raisamo. "Camera Based Target Acquisition Augmented with Phosphene Sensations". En Lecture Notes in Computer Science, 282–89. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-14100-3_42.

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Bhalla, Ashish. "Phosphate and Phosphine". En Critical Care Toxicology, 1875–85. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-17900-1_84.

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Bhalla, Ashish. "Phosphine and Metal Phosphide". En Critical Care Toxicology, 1–11. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-20790-2_84-1.

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Chen, Hao y Luwu He. "Catalytic activity for hydrogen evolution reaction in phosphene nanoribbons: A first-principles study". En Advances in Applied Chemistry and Industrial Catalysis, 292–97. London: CRC Press, 2022. http://dx.doi.org/10.1201/9781003308553-45.

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Fehervari, Tamas, Masaru Matsuoka, Hirotsugu Okuno y Tetsuya Yagi. "Real-Time Simulation of Phosphene Images Evoked by Electrical Stimulation of the Visual Cortex". En Neural Information Processing. Theory and Algorithms, 171–78. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-17537-4_22.

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Loubser, Christa, Simon Lotz y John E. Ellis. "Tricarbonyl Phosphine, Phosphite, and Arsine Derivatives of Cobalt(I)". En Inorganic Syntheses, 174–82. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2007. http://dx.doi.org/10.1002/9780470132609.ch42.

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Pasek, Matthew A. "Phosphine". En Encyclopedia of Astrobiology, 1229. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-11274-4_1186.

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Perkins, Michael W., Benjamin Wong, Dorian Olivera y Alfred Sciuto. "Phosphine". En Hamilton & Hardy's Industrial Toxicology, 1295–300. Hoboken, New Jersey: John Wiley & Sons, Inc., 2015. http://dx.doi.org/10.1002/9781118834015.ch118.

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Pasek, Matthew A. "Phosphine". En Encyclopedia of Astrobiology, 1858–59. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-44185-5_1186.

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Actas de conferencias sobre el tema "Phosphene"

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Feely, Grace y Young-A. Lee. "Phosphene". En Pivoting for the Pandemic. Iowa State University Digital Press, 2020. http://dx.doi.org/10.31274/itaa.11778.

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Nanduri, D., M. S. Humayun, R. J. Greenberg, M. J. McMahon y J. D. Weiland. "Retinal prosthesis phosphene shape analysis". En 2008 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE, 2008. http://dx.doi.org/10.1109/iembs.2008.4649524.

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Zhao, Ying, Kun Yang, Bo Pang, Yongji Wang y Qiushi Ren. "Simulated phosphene model for visual prosthesis". En 2012 5th International Conference on Biomedical Engineering and Informatics (BMEI). IEEE, 2012. http://dx.doi.org/10.1109/bmei.2012.6512915.

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Dagnelie, Gislin y Jacob V. Vogelstein. "Phosphene Mapping Procedures for Prosthetic Vision". En Vision Science and its Applications. Washington, D.C.: OSA, 1999. http://dx.doi.org/10.1364/vsia.1999.mb3.

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Bollen, Caroline J. M., Richard J. A. van Wezel, Marcel A. J. van Gerven y Yağmur Güçlütürk. "Emotion Recognition with Simulated Phosphene Vision". En the 2nd Workshop. New York, New York, USA: ACM Press, 2019. http://dx.doi.org/10.1145/3347319.3356836.

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Savage, Craig O. y Mark E. Halpern. "Phosphene brightness modelling for voltage driven waveforms". En 2011 Seventh International Conference on Intelligent Sensors, Sensor Networks and Information Processing (ISSNIP). IEEE, 2011. http://dx.doi.org/10.1109/issnip.2011.6146575.

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Okuno, H., T. Fehervari, M. Matsuoka, S. Kameda y T. Yagi. "Portable phosphene image generator simulating cortical visual prosthesis". En 2012 IEEE Biomedical Circuits and Systems Conference (BioCAS 2012). IEEE, 2012. http://dx.doi.org/10.1109/biocas.2012.6418465.

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Granley, Jacob y Michael Beyeler. "A Computational Model of Phosphene Appearance for Epiretinal Prostheses". En 2021 43rd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC). IEEE, 2021. http://dx.doi.org/10.1109/embc46164.2021.9629663.

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Perez-Yus, Alejandro, Jesus Bermudez-Cameo, Jose J. Guerrero y Gonzalo Lopez-Nicolas. "Depth and Motion Cues with Phosphene Patterns for Prosthetic Vision". En 2017 IEEE International Conference on Computer Vision Workshop (ICCVW). IEEE, 2017. http://dx.doi.org/10.1109/iccvw.2017.179.

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Zhao, Ying y Qiushi Ren. "Recognition of Chinese character formed by irregular simulated phosphene arrays". En 2012 11th International Conference on Signal Processing (ICSP 2012). IEEE, 2012. http://dx.doi.org/10.1109/icosp.2012.6492028.

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Informes sobre el tema "Phosphene"

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Raghothama, Kashchandra G., Avner Silber y Avraham Levy. Biotechnology approaches to enhance phosphorus acquisition of tomato plants. United States Department of Agriculture, enero de 2006. http://dx.doi.org/10.32747/2006.7586546.bard.

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Abstract: Phosphorus is one of the least available macronutrient in the soil. The high affinity phosphate transporters are known to be associated with phosphate acquisition under natural conditions. Due to unique interactions of phosphate with soil particles, up to 80% of the applied phosphates may be fixed forcing the farmers to apply 4 to 5 times the fertilizers necessary for crop production. Efficient uptake and utilization of this essential nutrient is essential for sustainability and profitability of agriculture. Many predictions point to utilization/exhaustion of high quality phosphate rocks within this century. This calls for efforts to improve the ability of plants to acquire and utilize limiting sources of phosphate in the rhizosphere. Two important molecular and biochemical components associated with phosphate efficiency are phosphate transporters and phosphatases. This research project is aimed at defining molecular determinants of phosphate acquisition and utilization in addition to generating phosphate uptake efficient plants. The main objectives of the project were; Creation and analysis of transgenic tomato plants over-expressing phosphatases and transporters Characterization of the recently identified members (LePT3 and LePT4) of the Pi transporter family Generate molecular tools to study genetic responses of plants to Pi deficiency During the project period we have successfully identified and characterized a novel phosphate transporter associated with mycorrhizal symbiosis. The expression of this transporter increases with mycorrhizal symbiosis. A thorough characterization of mutant tomato lacking the expression of this gene revealed the biological significance of LePT3 and another novel gene LePT4. In addition we have isolated and characterized several phosphate starvation induced genes from tomato using a combination of differential and subtractive mRNA hybridization techniques. One of the genes, LePS2 belongs to the family of phospho-protein phosphatase. The functionality of the recombinant protein was determined using synthetic phosphor-peptides. Over expression of this gene in tomato resulted in significant changes in growth, delay in flowering and senescence. It is anticipated that phospho-protein phosphatase may have regulatory role in phosphate deficiency responses of plants. In addition a novel phosphate starvation induced glycerol 3-phosphate permease gene family was also characterized. Two doctoral research students are continuing the characterization and functional analysis of these genes. Over expression of high affinity phosphate transporters in tobacco showed increased phosphate content under hydroponic conditions. There is growing evidence suggesting that high affinity phosphate transporters are crucial for phosphate acquisition even under phosphate sufficiency conditions. This project has helped train several postdoctoral fellows and graduate students. Further analysis of transgenic plants expressing phosphatases and transporters will not only reveal the biological function of the targeted genes but also result in phosphate uptake and utilization efficient plants.
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Collings, R. K. Phosphate. Natural Resources Canada/CMSS/Information Management, 1991. http://dx.doi.org/10.4095/328633.

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Chandler, F. W. y R. L. Christie. Stratiform phosphate. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1995. http://dx.doi.org/10.4095/207952.

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Hay, M. y W. King. PHOSPHATE MANAGEMENT: FY2010 RESULTS OF PHOSPHATE PRECIPITATION TESTS. Office of Scientific and Technical Information (OSTI), abril de 2011. http://dx.doi.org/10.2172/1013047.

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Grasby, S. E. y J. M. Galloway. Rare-earth elements of Permian through Cretaceous strata of the Sverdrup Basin, Nunavut and Northwest Territories. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/330202.

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This report provides new rare earth element (REE) data from Permian through to Late Cretaceous sedimentary rocks of the Sverdrup Basin, along with focused analyses on phosphate nodules that occur in the Middle Triassic Murray Harbour Formation. Results show the overall sedimentary values are low, however phosphate nodules are highly enriched in REEs.
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Lumetta, Gregg J., Jenifer C. Braley, Matthew K. Edwards, Odeta Qafoku, Andrew R. Felmy, Jennifer C. Carter y Paul J. MacFarlan. Removing Phosphate from Hanford High-Phosphate Tank Wastes: FY 2010 Results. Office of Scientific and Technical Information (OSTI), septiembre de 2010. http://dx.doi.org/10.2172/992014.

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Mailen, J. C. y O. K. Tallent. Separation of uranium and dibutyl phosphate contained in 30 vol % tributyl phosphate solvents. Office of Scientific and Technical Information (OSTI), julio de 1986. http://dx.doi.org/10.2172/5399500.

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Boyd, Bruce A. y Robert H. Neilson. Synthesis of (1,3-Disilylpropenyl)Phosphines. Fort Belvoir, VA: Defense Technical Information Center, enero de 1989. http://dx.doi.org/10.21236/ada204375.

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Zhang, X., A. Linsebigler, U. Heiz, J. T. Yates y Jr. Phosphine Chemistry on Mo(110) and Oxidized Mo(110). Fort Belvoir, VA: Defense Technical Information Center, enero de 1993. http://dx.doi.org/10.21236/ada266717.

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Anderson, M. A., W. A. Zeltner y C. G. Jr Hill. Development of phosphate-based ceramic membranes. Office of Scientific and Technical Information (OSTI), noviembre de 1992. http://dx.doi.org/10.2172/7164518.

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