Littérature scientifique sur le sujet « Plasmodi »
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Articles de revues sur le sujet "Plasmodi"
1
Solnica-Krezel, L., T. G. Burland et W. F. Dove. « Variable pathways for developmental changes of mitosis and cytokinesis in Physarum polycephalum. » Journal of Cell Biology 113, no 3 (1 mai 1991) : 591–604. http://dx.doi.org/10.1083/jcb.113.3.591.
Texte intégralRésumé :
The development of a uninucleate ameba into a multinucleate, syncytial plasmodium in myxomycetes involves a change from the open, astral mitosis of the ameba to the intranuclear, anastral mitosis of the plasmodium, and the omission of cytokinesis from the cell cycle. We describe immunofluorescence microscopic studies of the amebal-plasmodial transition (APT) in Physarum polycephalum. We demonstrate that the reorganization of mitotic spindles commences in uninucleate cells after commitment to plasmodium formation, is completed by the binucleate stage, and occurs via different routes in individual developing cells. Most uninucleate developing cells formed mitotic spindles characteristic either of amebae or of plasmodia. However, chimeric mitotic figures exhibiting features of both amebal and plasmodial mitoses, and a novel star microtubular array were also observed. The loss of the ameba-specific alpha 3-tubulin and the accumulation of the plasmodium-specific beta 2-tubulin isotypes during development were not sufficient to explain the changes in the organization of mitotic spindles. The majority of uninucleate developing cells undergoing astral mitoses (amebal and chimeric) exhibited cytokinetic furrows, whereas cells with the anastral plasmodial mitosis exhibited no furrows. Thus, the transition from astral to anastral mitosis during the APT could be sufficient for the omission of cytokinesis from the cell cycle. However, astral mitosis may not ensure cytokinesis: some cells undergoing amebal or chimeric mitosis contained unilateral cytokinetic furrows or no furrow at all. These cells would, most probably, fail to divide. We suggest that a uninucleate committed cell undergoing amebal or chimeric mitosis can either divide or else form a binucleate cell. In contrast, a uninucleate cell with a mitotic spindle of the plasmodial type gives rise only to a binucleate cells. Further, the decision to enter mitosis after commitment to the APT is independent of the developmental changes in the organization of the mitotic spindle and cytokinesis.
2
Salles-Passador, I., A. Moisand, V. Planques et M. Wright. « Physarum plasmodia do contain cytoplasmic microtubules ! » Journal of Cell Science 100, no 3 (1 novembre 1991) : 509–20. http://dx.doi.org/10.1242/jcs.100.3.509.
Texte intégralRésumé :
It has been claimed that the plasmodium of the myxomycete Physarum polycephalum constitutes a very unusual syncytium, devoid of cytoplasmic microtubules. In contrast, we have observed a cytoplasmic microtubule network, by both electron microscopy and immunofluorescence in standard synchronous plasmodia, either in semi-thin sections or in smears, and in thin plasmodia, used as a convenient model. Cytoplasmic microtubules could be seen after immunofluorescent staining with three different monospecific monoclonal anti-tubulin antibodies. The immunolabelling was strictly restricted to typical microtubules as shown by electron microscopy. These cytoplasmic microtubules were entirely and reversibly disassembled by cold treatment and by either of two microtubule poisons: methyl benzimidazole carbamate and griseofulvin. The microtubule network, present in all strains that have been studied, contains single microtubules and microtubule bundles composed of two to eight microtubules. Cytoplasmic microtubules form a dense and complex three-dimensional network, distinct from the microfilamentous domains and from the nuclei. The orientation of the microtubule network varies according to the plasmodial domain examined. Generally microtubules show no special orientation except in plasmodial veins where they are oriented parallel to the long axis of the veins. Differences between our observations and those of previous workers who failed to find cytoplasmic microtubules in plasmodia are discussed. We propose that they reflect difficulties of observation mainly due to the fluorescent background. In contrast with the previous view, the discovery of a microtubule cytoplasmic cytoskeleton in Physarum plasmodia raises several questions concerning its relationships with other cellular organelles and its dynamics during different cell cycle events.
3
Nunes, Alvaro, Vandana Thathy, Thomas Bruderer, Ali A. Sultan, Ruth S. Nussenzweig et Robert Ménard. « Subtle Mutagenesis by Ends-in Recombination in Malaria Parasites ». Molecular and Cellular Biology 19, no 4 (1 avril 1999) : 2895–902. http://dx.doi.org/10.1128/mcb.19.4.2895.
Texte intégralRésumé :
ABSTRACT The recent advent of gene-targeting techniques in malaria (Plasmodium) parasites provides the means for introducing subtle mutations into their genome. Here, we used the TRAPgene of Plasmodium berghei as a target to test whether an ends-in strategy, i.e., targeting plasmids of the insertion type, may be suitable for subtle mutagenesis. We analyzed the recombinant loci generated by insertion of linear plasmids containing either base-pair substitutions, insertions, or deletions in their targeting sequence. We show that plasmid integration occurs via a double-strand gap repair mechanism. Although sequence heterologies located close (less than 450 bp) to the initial double-strand break (DSB) were often lost during plasmid integration, mutations located 600 bp and farther from the DSB were frequently maintained in the recombinant loci. The short lengths of gene conversion tracts associated with plasmid integration intoTRAP suggests that an ends-in strategy may be widely applicable to modify plasmodial genes and perform structure-function analyses of their important products.
4
SHIRAKAWA, TOMOHIRO, ANDREW ADAMATZKY, YUKIO-PEGIO GUNJI et YOSHIHIRO MIYAKE. « ON SIMULTANEOUS CONSTRUCTION OF VORONOI DIAGRAM AND DELAUNAY TRIANGULATION BY PHYSARUM POLYCEPHALUM ». International Journal of Bifurcation and Chaos 19, no 09 (septembre 2009) : 3109–17. http://dx.doi.org/10.1142/s0218127409024682.
Texte intégralRésumé :
We experimentally demonstrate that both Voronoi diagram and its dual graph Delaunay triangulation are simultaneously constructed — for specific conditions — in cultures of plasmodium, a vegetative state of Physarum polycephalum. Every point of a given planar data set is represented by a tiny mass of plasmodium. The plasmodia spread from their initial locations but, in certain conditions, stop spreading when they encounter plasmodia originated from different locations. Thus space loci not occupied by the plasmodia represent edges of Voronoi diagram of the given planar set. At the same time, the plasmodia originating at neighboring locations form merging protoplasmic tubes, where the strongest tubes approximate Delaunay triangulation of the given planar set. The problems are solved by plasmodium only for limited data sets, however the results presented lay a sound ground for further investigations.
5
Wu, Yuyang, Peng Xie, Qi Ding, Yuhang Li, Ling Yue, Hong Zhang et Wei Wang. « Magnetic plasmons in plasmonic nanostructures : An overview ». Journal of Applied Physics 133, no 3 (21 janvier 2023) : 030902. http://dx.doi.org/10.1063/5.0131903.
Texte intégralRésumé :
The magnetic response of most natural materials, characterized by magnetic permeability, is generally weak. Particularly, in the optical range, the weakness of magnetic effects is directly related to the asymmetry between electric and magnetic charges. Harnessing artificial magnetism started with a pursuit of metamaterial design exhibiting magnetic properties. The first demonstration of artificial magnetism was given by a plasmonic nanostructure called split-ring resonators. Engineered circulating currents form magnetic plasmons, acting as the source of artificial magnetism in response to external electromagnetic excitation. In the past two decades, magnetic plasmons supported by plasmonic nanostructures have become an active topic of study. This Perspective reviews the latest studies on magnetic plasmons in plasmonic nanostructures. A comprehensive summary of various plasmonic nanostructures supporting magnetic plasmons, including split-ring resonators, metal–insulator–metal structures, metallic deep groove arrays, and plasmonic nanoclusters, is presented. Fundamental studies and applications based on magnetic plasmons are discussed. The formidable challenges and the prospects of the future study directions on developing magnetic plasmonic nanostructures are proposed.
6
Honkonen, I., M. Palmroth, T. I. Pulkkinen, P. Janhunen et A. Aikio. « On large plasmoid formation in a global magnetohydrodynamic simulation ». Annales Geophysicae 29, no 1 (14 janvier 2011) : 167–79. http://dx.doi.org/10.5194/angeo-29-167-2011.
Texte intégralRésumé :
Abstract. We investigate plasmoid formation in the magnetotail using the global magnetohydrodynamic (MHD) simulation GUMICS-4. Here a plasmoid implies a major reconfiguration of the magnetotail where a part of the tail plasma sheet is ejected downstream, in contrast to small Earthward-propagating plasmoids. We define a plasmoid based solely on the structure of the closed (connected to the Earth at both ends) magnetic field line region. In this definition a plasmoid is partly separated from the ordinary closed field line region by lobe field lines or interplanetary field lines resulting from lobe reconnection. We simulate an event that occurred on 18 February 2004 during which four intensifications of the auroral electroject (AE) index occurred in 8 h. Plasmoids form in the simulation for two of the four AE intensifications. Each plasmoid forms as a result of two consecutive large and fast rotations of the interplanetary magnetic field (IMF). In both cases the IMF rotates 180 degrees at 10 degrees per minute, first from southward to northward and some 15 min later from northward to southward. The other two AE intencifications however are not associated with a plasmoid formation. A plasmoid does not form if either the IMF rotation speed or the angular change of the rotation are small. We also present an operational definition for these fully connected plasmoids that enables their automatic detection in simulations. Finally, we show mappings of the plasmoid footpoints in the ionosphere, where they perturb the polar cap boundary in both hemispheres.
7
Suzuki, Y., T. H. Watanabe, A. Kageyama, T. Sato et T. Hayashi. « Three-Dimensional Simulation Study of Plasmoid Injection into Magnetized Plasma ». Symposium - International Astronomical Union 188 (1998) : 209–10. http://dx.doi.org/10.1017/s0074180900114780.
Texte intégralRésumé :
Resent observations suggest that, during solar flares, plasmoids are injected into the interplanetary medium (Stewart et al., 1982). It has also been pointed out that solar wind irregularities modeled as plasmoids are penetrated into the magnetosphere (Lemaire, 1977). These plasmoid injections are considered to be an important process because they transfer mass, momentum, and energy into such magnetized plasma regions. Our objective is to investigate the dynamics of a plasmoid, which is injected into a magnetized plasma region and to reveal mechanisms to transfer them. To achieve this, we carried out three-dimensional magnetohydrodynamic (MHD) simulations.
8
He, Zhicong, Fang Li, Yahui Liu, Fuqiang Yao, Litu Xu, Xiaobo Han et Kai Wang. « Principle and Applications of the Coupling of Surface Plasmons and Excitons ». Applied Sciences 10, no 5 (4 mars 2020) : 1774. http://dx.doi.org/10.3390/app10051774.
Texte intégralRésumé :
Surface plasmons have been attracting increasing attention and have been studied extensively in recent decades because of their half-light and half-material polarized properties. On the one hand, the tightly confined surface plasmonic mode may reduce the size of integrated optical devices beyond the diffraction limit; on the other hand, it provides an approach toward enhancement of the interactions between light and matter. In recent experiments, researchers have realized promising applications for surface plasmons in quantum information processing, ultra-low-power lasers, and micro-nano processing devices by using plasmonic structures, which have demonstrated their superiority over traditional optics structures. In this paper, we introduce the theoretical principle of surface plasmons and review the research work related to the interactions between plasmons and excitons. Some perspectives with regard to the future development of plasmonic coupling are also outlined.
9
Solnica-Krezel, L., M. Diggins-Gilicinski, T. G. Burland et W. F. Dove. « Variable pathways for developmental changes in composition and organization of microtubules in Physarum polycephalum ». Journal of Cell Science 96, no 3 (1 juillet 1990) : 383–93. http://dx.doi.org/10.1242/jcs.96.3.383.
Texte intégralRésumé :
The development of uninucleate amoebae into multinucleate plasmodia in myxomycetes is called the amoebal-plasmodial transition (APT). During the APT in Physarum polycephalum the ability to form flagellar axonemes is lost; the astral, open mitosis is replaced by the anastral, closed mitosis; and cytoskeletal microtubules disappear. These changes are accompanied by alterations in the repertoire of expressed tubulins. Using immunofluorescence microscopy we have studied the timing of loss and accumulation of developmentally regulated tubulin isotypes in relation to other cellular events during the APT. We specifically asked whether changes in the composition of microtubules are correlated with changes in their organization. The plasmodium-specific beta 2-tubulin can first be detected in microtubules of uninucleate cells after they become committed to plasmodium formation. However, rare cells are observed that exhibit beta 2-tubulin at earlier or only at later stages of development. Amoeba-specific acetylated alpha 3-tubulin disappears gradually during development. Individual cells differ in the timing of loss of this isotype: alpha 3-tubulin is present in the majority of uninucleate cells, in a fraction of binucleate and quadrinucleate cells, and is absent from larger multinucleate cells. Cytoplasmic microtubules in uninucleate cells are organized by a single microtubule-organizing center (MTOC) juxtaposed to the nucleus. Binucleate cells and quadrinucleate cells exhibit variable numbers of MTOCs. Cytoplasmic microtubules persist during the APT until the stage of plasmodia containing at least 100 nuclei. The lack of a strict correlation between the changes in tubulin composition and changes in organization of microtubular structures indicates that accumulation of beta 2-tubulin and disappearance of alpha 3-tubulin isotypes are not sufficient to bring about reorganization of microtubules during development. Individual cells in a developing population differ not only in the succession of accumulation and loss of developmentally regulated tubulins, but also in the sequences of other cellular changes occurring during the APT.
10
Tao, Z. H., H. M. Dong et Y. F. Duan. « Anomalous plasmon modes of single-layer MoS2 ». Modern Physics Letters B 33, no 18 (26 juin 2019) : 1950200. http://dx.doi.org/10.1142/s0217984919502002.
Texte intégralRésumé :
The electronic plasmons of single layer MoS2 induced by different spin subbands owing to spin-orbit couplings (SOCs) are theoretically investigated. The study shows that two new and anomalous plasmonic modes can be achieved via inter-spin subband transitions around the Fermi level due to the SOCs. The plasmon modes are optic-like, which are very different from the plasmons reported recently in single-layer (SL) MoS2, and the other two-dimensional systems. The frequency of such plasmons ascends with the increasing of electron density or spin polarizability, and decreases with the increasing of wave vector. The promising plasmonic properties of SL MoS2 make it interesting for future applications in plasmonic and terahertz devices.
Thèses sur le sujet "Plasmodi"
1
Ramirez, Francisco. « Surface Plasmon Hybridization in Novel Plasmonic Phenomena ». Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/917.
Texte intégralRésumé :
We explore the effects of surface plasmon hybridization in graphene nanostructures and silver nanoparticles as applied to novel plasmonic phenomena. The analysis is based on the theory of surface plasmon hybridization under the boundary charges method. This method, which is based in the electrostatic approximation, has been largely used to predict the resonant frequencies in strongly coupled nanoparticle clusters. Here, we extend this formalism to analyze novel plasmonic phenomena such as the blueshift of modes in graphene plasmonics, near-field radiation, thermal transport and plasmon-induced hot carrier generation in silver nanoparticles. Furthermore, we develop analytical solutions for graphene nanodisks and metallic spheres that allow for fast and accurate modeling. The analytic models provide the basis to derive a large number of results, including prediction of hybrid eigenmodes and bandstructures, far-field response, and near-field response under thermally induced fluctuations. We predict that the strong near-filed coupling in graphene nanodisk stacks can induce a blueshift in the resonant frequencies up to the near-infrared part of the spectrum. We find that the strong near-filed coupling between disks can also lead to large values of radiative thermal conductance when thermally induced fluctuations are included. In this regard, an enhancement over the blackbody limit of up to two and four orders of magnitude was observed for co-planar and co-axial disk configurations. The strong coupling between coplanar disks was also explored for the development of plasmonic waveguides by considering long co-planar disk arrays. It was observed that the array posseses great potential for plasmonic waveguiding, with a strong degree of confinement for disks smaller than 200 nm. Thermal activation of the guided modes showed a thermal conductivity of up to 4.5 W/m K and thermal diffusivity of up to 1:4 x 10-3 m2/s. The large values of thermal diffusivity suggest the potential of graphene disk waveguides for thermotronic interconnects. The plasmon-induced hot carrier generation in silver nanosphere dimers was also studied. The modeling considered analytical solution for metallic nanospheres, from which the electrostatic potential of each sphere was obtained. Using these results, the hot carrier generation was explored under the basis of the Fermi golden rule. The results show a large number of hot carriers at the low frequency modes. This values exceed the number of generated hot carriers on a single sphere. The energy distribution of photogenerated electrons and holes showed a large energy gap that can be explored in photocatalysis and photovoltaic energy conversion.
2
Tan, Shiaw Juen. « Linear and nonlinear propagation of localised plasmon in metallic nanostructures ». Thesis, Queensland University of Technology, 2011. https://eprints.qut.edu.au/52635/1/Shiaw_Tan_Thesis.pdf.
Texte intégralRésumé :
A major challenge in modern photonics and nano-optics is the diffraction limit of light which does not allow field localisation into regions with dimensions smaller than half the wavelength. Localisation of light into nanoscale regions (beyond its diffraction limit) has applications ranging from the design of optical sensors and measurement techniques with resolutions as high as a few nanometres, to the effective delivery of optical energy into targeted nanoscale regions such as quantum dots, nano-electronic and nano-optical devices. This field has become a major research direction over the last decade. The use of strongly localised surface plasmons in metallic nanostructures is one of the most promising approaches to overcome this problem. Therefore, the aim of this thesis is to investigate the linear and non-linear propagation of surface plasmons in metallic nanostructures. This thesis will focus on two main areas of plasmonic research –– plasmon nanofocusing and plasmon nanoguiding.
Plasmon nanofocusing – The main aim of plasmon nanofocusing research is to focus plasmon energy into nanoscale regions using metallic nanostructures and at the same time achieve strong local field enhancement. Various structures for nanofocusing purposes have been proposed and analysed such as sharp metal wedges, tapered metal films on dielectric substrates, tapered metal rods, and dielectric V-grooves in metals. However, a number of important practical issues related to nanofocusing in these structures still remain unclear. Therefore, one of the main aims of this thesis is to address two of the most important of issues which are the coupling efficiency and heating effects of surface plasmons in metallic nanostructures. The method of analysis developed throughout this thesis is a general treatment that can be applied to a diversity of nanofocusing structures, with results shown here for the specific case of sharp metal wedges. Based on the geometrical optics approximation, it is demonstrated that the coupling efficiency from plasmons generated with a metal grating into the nanofocused symmetric or quasi-symmetric modes may vary between ~50% to ~100% depending on the structural parameters. Optimal conditions for nanofocusing with the view to minimise coupling and dissipative losses are also determined and discussed. It is shown that the temperature near the tip of a metal wedge heated by nanosecond plasmonic pulses can increase by several hundred degrees Celsius. This temperature increase is expected to lead to nonlinear effects, self-influence of the focused plasmon, and ultimately self-destruction of the metal tip. This thesis also investigates a different type of nanofocusing structure which consists of a tapered high-index dielectric layer resting on a metal surface. It is shown that the nanofocusing mechanism that occurs in this structure is somewhat different from other structures that have been considered thus far. For example, the surface plasmon experiences significant backreflection and mode transformation at a cut-off thickness. In addition, the reflected plasmon shows negative refraction properties that have not been observed in other nanofocusing structures considered to date.
Plasmon nanoguiding – Guiding surface plasmons using metallic nanostructures is important for the development of highly integrated optical components and circuits which are expected to have a superior performance compared to their electronicbased counterparts. A number of different plasmonic waveguides have been considered over the last decade including the recently considered gap and trench plasmon waveguides. The gap and trench plasmon waveguides have proven to be difficult to fabricate. Therefore, this thesis will propose and analyse four different modified gap and trench plasmon waveguides that are expected to be easier to fabricate, and at the same time acquire improved propagation characteristics of the guided mode. In particular, it is demonstrated that the guided modes are significantly screened by the extended metal at the bottom of the structure. This is important for the design of highly integrated optics as it provides the opportunity to place two waveguides close together without significant cross-talk. This thesis also investigates the use of plasmonic nanowires to construct a Fabry-Pérot resonator/interferometer. It is shown that the resonance effect can be achieved with the appropriate resonator length and gap width. Typical quality factors of the Fabry- Pérot cavity are determined and explained in terms of radiative and dissipative losses. The possibility of using a nanowire resonator for the design of plasmonic filters with close to ~100% transmission is also demonstrated.
It is expected that the results obtained in this thesis will play a vital role in the development of high resolution near field microscopy and spectroscopy, new measurement techniques and devices for single molecule detection, highly integrated optical devices, and nanobiotechnology devices for diagnostics of living cells.
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Mejia, Pedro. « Amélioration et utilisation d'un modèle murin des stades érythrocytaires du paludisme humain ». Rouen, 2006. http://www.theses.fr/2006ROUES062.
Texte intégral
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Lupetti, Mattia. « Plasmonic generation of attosecond pulses and attosecond imaging of surface plasmons ». Diss., Ludwig-Maximilians-Universität München, 2015. http://nbn-resolving.de/urn:nbn:de:bvb:19-183678.
Texte intégralRésumé :
Attosecond pulses are ultrashort radiation bursts produced via high
harmonic generation (HHG) during a highly nonlinear excitation process
driven by a near infrared (NIR) laser
pulse. Attosecond pulses can be used
to probe the electron dynamics in ultrafast processes via the attosecond
streaking technique, with a resolution on the
attosecond time scale.
In this thesis it is shown that both the generation of attosecond (AS) pulses
and the probing of ultrafast processes by means of AS pulses, can
be extended to cases in which the respective driving and streaking fields are produced by
surface plasmons excited on nanostructures at NIR wavelengths.
Surface plasmons are optical modes generated by collective oscillations of the surface
electrons in resonance with an external source.
In the first part of this thesis, the idea of high harmonic generation (HHG)
in the enhanced field of a surface plasmon is analyzed in detail by means of numerical simulations.
A NIR pulse is coupled
into a surface plasmon propagating in a hollow core tapered
waveguide filled with noble gas. The plasmon field intensity
increases for decreasing waveguide radius, such that at the apex
the field enhancement is sufficient for producing high harmonic radiation.
It is shown that with this setup it is possible to generate isolated AS pulses
with outstanding spatial and temporal structure, but with an intensity of orders of magnitude smaller than in standard gas harmonic
arrangements.
In the second part, an experimental technique for the imaging
of surface plasmonic excitations on nanostructured surfaces is proposed,
where AS pulses are used to probe the surface field by means of
photoionization. The concept constitutes an
extension of the attosecond streak camera
to ``Attosecond Photoscopy'', which allows
space- and time-resolved imaging of the plasmon dynamics during
the excitation process. It is numerically demonstrated that the relevant parameters of the
plasmonic resonance buildup phase can be determined with subfemtosecond precision.
Finally, the method used for the numerical solution of
the Maxwell's equations is discussed, with
particular attention to the problem of absorbing boundary conditions.
New insights into the mathematical formulation of the absorbing
boundary conditions for Maxwell's equations are provided.Attosekundenpulse sind ultrakurze extrem-ultraviolette (XUV) Pulse, die durch einen nicht-linearen, von einer nah-infraroten (NIR) Laserquelle stimulierten Anregungsprozess erzeugt werden. Attosekundenpulse können verwendet werden, um die Elektronendynamik eines ultraschnellen Prozesses durch die ``Attosecond Streaking'' Technik zu messen, mit einer Auflösung auf der Attosekundenskala. In dieser Dissertation wird gezeigt, dass sowohl die Erzeugung von Attosekundenpulsen als auch die Messung ultraschneller Prozesse mittels Attosekundenpulse auf Fälle erweitert werden können, bei denen die Anregungs- und Streakingsfelder von Oberflächenplasmonen generiert werden, welche bei nahinfraroten Wellenlängen auf Nanostrukturen angeregt werden. Oberflächenplasmonen sind optische Moden, die aus einer kollektiven Schwingung der Elektronen an der Oberfläche in Resonanz mit einer externen Quelle entstehen. Im ersten Abschnitt dieser Dissertation wird das Konzept der High Harmonic Generation (HHG) in plasmonisch erhöhten Feldern durch numerische Simulationen analysiert. Ein NIR Puls wird mit einem Oberflächenplasmon, das sich in einem konischen, mit Edelgas gefüllten, Hohlleiter ausbreitet, gekoppelt. Die Intensität des plasmonischen Feldes steigt mit der Verringerung des Durchmessers des Hohlleiters, sodass die Felderhöhung an seiner Spitze groß genug wird, um hohe harmonische Strahlung zu generieren. Es wird nachgewiesen, dass die Herstellung von isolierten Attosekundenpulsen mit außergewöhnlichen Zeit- und Raumstrukturen möglich ist. Trotzdem ist deren Intensität um mehrere Größenordnungen niedriger als die, die in Experimenten mit fokussierten Laserpulsen erreicht werden kann. Im zweiten Abschnitt wird eine experimentelle Technik für die Abbildung plasmonischer Oberflächenanregungen vorgeschlagen, wobei Attosekundenpulse verwendet werden, um das Feld an der Oberfläche mittels ``Momentum Streaking'' der photoionisierten Elektronen zu messen. Dieses Konzept ist eine Erweiterung der ``Attosecond Streak Camera'', welches ich ``Attosecond Photoscopy'' nenne. Es ermöglicht die Abbildung eines Plasmons in Zeit und Raum während des Anregungsprozesses. Anhand von numerischen Simulationen wird es gezeigt, dass die wesentlichen Parameter des plasmonischen Resonanzaufbaus mit subfemtosekunden-Präzision bestimmt werden können. Zuletzt wird die Methode für die numerische Lösung der Maxwell-Gleichungen diskutiert, mit Fokus auf das Problem der absorbierenden Randbedingungen. Neue Einsichten in die mathematische Formulierung der Randbedingungen der Maxwell-Gleichungen werden vorgestellt.
5
Henry, Véronique. « Récepteurs érythrocytaires impliqués dans la pénétration du "Plasmodium" dans l'hématie ». Paris 5, 1988. http://www.theses.fr/1988PA05P102.
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Malhotra, Khushbeer. « Etude "in vitro" de l'action des constituants du système microbicide des polynucléaires humains sur les formes aséxuées de "Plasmodium falciparum" : influence de leur association avec divers antimalariques ». Paris 5, 1988. http://www.theses.fr/1988PA05P620.
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Udo, Edet Ekpenyong. « Characterisation and molecular studies of plasmids from Nigerian staphylococci ». Thesis, Curtin University, 1991. http://hdl.handle.net/20.500.11937/1845.
Texte intégralRésumé :
Fifty three Staphylococcus aureus isolates were obtained from three centres, two hospitals and a private pathology laboratory, and studied for susceptibility to bacteriophages, resistance to antimicrobial agents and plasmid contents.Results of bacteriophage typing revealed that they belonged to a variety of phage types. Eighteen were untypable by any of the International Set of Phages, 16 belonged to phage group 111, nine to group I, four to group 11, two to group IV and two to the miscellaneous group.The isolates were resistant to one or more of methicillin (Mc), benzyl penicillin (Pc), gentamicin (Gm) , kanamycin (Km) , neomycin (Nm) , streptomycin (Sm) , trimethoprim (Tp), sulphonamides (Su), tetracycline (Tc), minocycline (Mn), chloramphenicol (Cm), novobiocin (Nb) and fusidic acid (Fa). Resistance to Pc was due to the production of beta-lactamase (Bla). No resistance to vancomycin, spectinomycin and erythromycin was detected. Resistance was also found to heavy metals such as cadmium (Cd), mercury (Hg), phenyl mercuric acetate (Pma), arsenate (Asa) and to the nucleic-acid binding compounds propamidine isethionate (Pi) and ethidium bromide (Eb).All but one of the isolates harboured plasmids. The number of plasmids the isolates carried varied from one to six and their sizes ranged from < 1.0 kb to c.48 kb.Location of the resistance determinants was ascertained by curing and transfer experiments. Loss of resistance was tested after growth at 43.5°C and transfer of resistance determinants was attempted by transduction, mixed-culture transfer and conjugation. The results revealed that resistance to Mc, Gm, Tp, Mn and Fa was chromosomal in all the resistant isolates and in some isolates Bla and resistance to Sm and Cd were chromosomal as well as plasmid encoded. In the majority of cases Bla and resistance to Km, Nm, Sm, Tc, Cin, Cd, Hg, Asa, Pma, Pi and Eb was encoded by plasmids.Conjugation experiments led to the isolation of three unique conjugative plasmids which have not been found to confer resistance to antimicrobials or to produce haemolysins or diffusible pigment (Dip). The three plasmids, pWBG620, pWBG637 and pWBG661, were indistinguishable by restriction endonuclease analysis and DNA-DNA hybridisation. However pWBG620, unlike pWBG637 and pWBG661, was not detected in the cytoplasm of its host and was only detected in transconjugants after it mobilised a non-conjugative Sm-resistance (SmR) plasmid. Further analysis indicated that it is integrated into the chromosome of its host, excises during conjugation and mobilises the SmR plasmid.These plasmids were studied further using pWBG637 as a representative. It was compared with representatives of the two groups of conjugative plasmids which have been reported in the staphylococci. These are the plasmids which encode resistance to Gm, Km and Nm and those which code for the production of diffusible pigment. The three types of conjugative plasmids were compared by restriction endonuclease analysis and DNA- DNA hybridisation and were found to be different. A preliminary restriction map of pWBG637 has also been constructed.However since pWBG637 has no resistance phenotype direct selection for it was not possible in transfer experiments and for incompatibility (Inc.). To study it further it was necessary to construct resistant derivatives which could be selected for in transfer experiments. This was achieved by labelling pWBG637 with resistance transposons to generate two conjugative plasmids, pWBG636 carrying an insert of Tn3851 (Gm- resistance) and pWBG642 carrying an insert of Tn551 (hn- resistance). It was found that transposon labelling had not changed the incompatibility of pWBG637 and therefore pWBG636 and pWBG642 were used in further experiments in place of pWBG637. Inc. tests with the pWBG637 derivatives revealed that the pWBG637 type of plasmid is not only different from the other two types of conjugative plasmids but is different from any of the described staphylococcal Inc. groups and therefore the pWBG637 type of plasmids represent a new Inc. group 15. The pWBG637 type of plasmids were studied further using plasmids pWBG636 and pWBG642. They were able to transfer conjugatively to a capsulated S.aureus strain either by the polyethylene glycol method or on filter membranes. They also transferred by conjugation to S. epidermidis and Streptococcus faecalis and were able to transfer back from these strains to S.aureus indicating that they also replicate in these hosts. Consequently they have been used to mobilise non-conjugative plasmids from S.epidermidis and non phage typable S.aureus. Both plasmids failed to transfer conjugatively to Bacillus subtilis and Escherichia coli.pWBG637 transferred non-conjugative plasmids by mobilising them in a manner similar to mobilisation (donation) in E.coli or by recombining with them to form new resistance plasmids. In one case, pWBG628 which encodes Bla and resistance to Cd, Km, Nm and Sm and has no homology with pWBG637 recombined with it during conjugation to produce three new conjugative plasmids pWBG629, pWBG630 and pWBG631 carrying resistance determinants from pWBG628. One of these plasmids, pWBG629, was found to be pWBG637 which had acquired a 4.5 kb element encoding resistance to Km, Nm and Sm. This element was shown to be transposable in both rec+ and rec- backgrounds and has been designated Tn3854. It expressed Sm resistance in E.coli and differs on this account from the Gram-negative transposon Tn5 which expresses resistance to Km, Nm and Sm in non-enteric bacteria but only resistance to Km and Nm in E. coli.Where possible the non-conjugative plasmids encoding resistance to antimicrobial agents were compared with phenotypically similar plasmids isolated from other parts of the world. It was found that the Tc and Sm resistance plasmids were closely related to other plasmids with the same phenotype whereas the Cm resistance plasmids were different.Although the majority of the Bla plasmids belonged to Inc. group 1 they demonstrated significant restriction enzyme fragment length polymorphism when compared with other Bla plasmids.This study has provided the first data on the genetics of antimicrobial resistance in Nigerian S.aureus. Although many of the plasmids studied were found to be similar to those previously described the isolates also contained some unique and previously undescribed plasmids.
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Jansen, Yvette. « Characterisation of a high copy number mutant pAL5000 origin of replication ». Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52159.
Texte intégralRésumé :
Thesis (MScMedSc)--Stellenbosch University, 2001.ENGLISH ABSTRACT: The plasmid pAL5000 is a mycobacterial plasmid isolated from Mycobacterium fortuitum. It is a low copy number plasmid, which replicates in both fast growing (e.g. M. smegmatis) and slow growing (e.g. M. bovis BCG) mycobacteria. Most mycobacterial-E. coli shuttle vectors utilise the pAL5000 origin of replication. The minimum replicon consists of ORF1 (RepA), ORF2 (RepB) and the origin of replication. Dr W.R. Bourn created an E. coli-mycobacterial vector based on the pAL5000 origin of replication (pORI) and then subjected it to semi-random mutagenesis. A high copy number mutant was identified (pHIGH) and the causative mutation was tentatively identified as a 3bp deletion situated just upstream of repB. This work describes the further characterisation of the mutant plasmid. Firstly, it was shown by retransforming M. smegmatis with both the original and mutant plasmids (pORI and pHIGH), that the mutation causing the increased copy number was plasmid-encoded and not on the chromosome. Following this, it was demonstrated by simple subcloning of the region that carries the 3 bp deletion, that other pAL5000-based vectors could be converted to high copy number. In addition to this, the subcloned region was sequenced and the nature of the mutations was confirmed. The subcloning experiment confirmed that the 3bp deletion caused the high copy number phenotype. Following this, the exact copy number of pHIGH and the relative increase in copy number was determined. From this, the copy number of pORI could also be determined. The plasmid pHIGH has a copy number of approximately 54, compared to the 8 of pORI (a relative increase by a factor of 7). Because it is important for researchers to know the characteristics of the vectors that they use, especially the influence it will have on its host, stability tests and growth curves were also performed. It was seen that the higher copy number did not markedly increase the stability, however, this is because pORI is already extremely, and unexpectedly, stable in the host M. smegmatis. According to the growth curves, the increased copy number has little effect on the growth of the host M. smegmatis. Possible mechanisms for the increased copy number were then investigated. By using a promoter probe vector, the possible existence of a promoter situated between the two open reading frames of pAL5000 (repA and repB) was investigated. It was thought that the mutation might have created, or changed an existing promoter, situated between repA and repB. The results showed, however, that in both pORI and pHIGH there might be a very weak promoter upstream of repB, but the mutation did not cause any change that was measurable by the method that was used. A further possibility was that the mutation caused a change in the RNA secondary structure, which might then have an effect on the translational efficiency of RepB. It was found that the 3bp deletion in pHIGH causes a change in the local RNA secondary structure around the ribosomal binding site and the start codon, when compared to pORI (wild type). This change may cause the translation initiation rate of RepB to be different between pHIGH and pORI. Ultimately it would lead to a different ratio of RepA and RepB in the cell.
AFRIKAANSE OPSOMMING: Die plasmied pAL5000 is ‘n mikobakteriele plasmied wat vanuit Mycobacterium fortuitum gei'soleer is. Dit is ‘n lae kopie-getal plasmied wat in beide vinnig groeiende (bv. M. smegmatis) en stadig groeiende (bv. M. bovis BCG) mikobakteriee kan repliseer. Die meeste mikobakteriele-E. coli shuttle vektore gebruik die pAL5000 oorsprong van replisering. Die minimum replikon bestaan uit ORF1 (RepA), ORF2 (RepB) en die oorsprong van replisering. Dr. W.R. Bourn het ‘n E. coli-mikobakteriele vektor gemaak wat gebaseer is op die pAL5000 oorsprong van replisering (pORI), en dit onderwerp aan semi-random mutagenese. ‘n Hoë kopie-getal mutant is gei'dentifiseer (pHIGH) en die mutasie hiervoor verantwoordelik was tentatief gei'dentifiseer as ‘n 3bp delesie, net stroomop van repB. Die projek beskryf die verdere karakterisering van die mutante plasmied. Eerstens, deur M. smegmatis te hertransformeer met die plasmied DNA (pORI en pHIGH), is dit bewys dat dit mutasie wat die toename in kopie-getal veroorsaak, deur die plasmied gekodeer word, en dat dit nie ‘n mutasie op die chromosoom is nie. Hierna is dit deur eenvoudige subklonering bewys dat die gedeelte wat die 3bp delesie dra, ander pAL5000-gebaseerde vektore ook kan verander in ‘n hoër kopie-getal. Die sub-klonerings eksperiment het ook bewys dat die 3 bp delesie die oorsaak is vir die hoë kopie-getal fenotipe. Volgende is die presiese kopie-getal van pHIGH en die relatiewe toename in kopiegetal bepaal. Die kopie-getal van pORI kon vanaf hierdie data bepaal word. Die plasmied pHIGH het ‘n kopie-getal van ongeveer 54 in M. smegmatis, in vergelyking met die 8 van pORI (‘n relatiewe toename met ‘n faktor van 7). Aangesien dit vir navorsers belangrik is om die eienskappe van die vektore wat hulle gebruik, te ken, en veral die invloed wat dit op die gasheer sal hê, is stabiliteits toetse, en groeikurwes gedoen. Die hoër kopie-getal het nie die stabiliteit werklik verbeter nie, maar dit is omdat pORI alreeds uiters stabiel is in die gasheer M. smegmatis. Volgens die groeikurwes het die toename in kopie-getal ‘n minimale effek op die groei van die gasheer M. smegmatis. Moontlike meganismes vir die hoër kopie-getal is ook ondersoek. Die moontlike bestaan van ‘n promoter tussen die twee oop-leesrame van pAL5000 (repA en repB) is ondersoek deur gebruik te maak van ‘n “promoter probe” vektor. Die mutasie kon moontlik ‘n promoter geskep het, of ‘n bestaande een tussen repA en repB verander het. Die resultate het gewys dat daar in beide pORI en pHIGH moontlik ‘n baie swak promoter stroomop van repB is, maar die mutasie het nie enige veranderinge veroorsaak wat meetbaar was met die metode wat gebruik is nie. ‘n Verdere moontlikheid was dat die mutasie ‘n verandering in die RNA sekondere struktuur kon veroorsaak het, en dit mag ‘n effek hê op die translasie effektiwiteit van RepB. Daar is gevind dat, in vergelyking met pORI, het die 3bp delesie in pHIGH ‘n verandering in die lokale RNA sekondere struktuur rondom die ribosomale bindings posisie en die begin-kodon veroorsaak. Die verandering mag veroorsaak dat die translasie inisiasie tempo van RepB verskillend is vir pORI en pHIGH. Uiteindelik sal dit lei tot ‘n heeltemal ander verhouding van RepA en RepB in die sel.
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Duval, Linda. « Diversité, évolution, co-spéciation et capture d'hôte chez les Haemosporidia de la faune sauvage de Madagascar et du Cambodge ». Paris, Muséum national d'histoire naturelle, 2007. http://www.theses.fr/2007MNHN0019.
Texte intégralRésumé :
Cette thèse contribue, par différents aspects, morphologiques, moléculaires et phylogénétiques, à une meilleure connaissance de la diversité des parasites de l’ordre des Haemosporidia chez les vertébrés des classes des oiseaux, reptiles et mammifères dans deux hot spots de biodiversité, à Madagascar et au Cambodge. Un atlas des Haemosporidia de la faune sauvage de Madagascar et du Cambodge a été constitué pour mettre à disposition nos données. L’aspect moléculaire a concerné la caractérisation et l’identification avec quatre marqueurs moléculaires (cyt b, tufA, ldh et cox 1) des parasites. L’utilisation de différents marqueurs moléculaires a permis de comparer leurs degrés d’informations phylogénétiques et de montrer que les gènes mitochondriaux, cyt b et cox 1 permettaient une meilleure résolution des constructions phylogénétiques que celles réalisées avec le gène de l’apicoplaste tufA ou le gène nucléaire ldh. Les analyses phylogénétiques, ont permis de mettre en évidence des évènements de capture d’hôte entre deux classes de vertébrés, les oiseaux et les mammifères (chauves-souris). Un scénario de coévolution hôte parasite a été proposé pour les Plasmodium des primates (incluant P. Falciparum chez l’homme) et la famille d’hôte des Hominidae. Une estimation de la datation de l’apparition de P. Falciparum entre 7 et 9 millions d’années a été déduite de ce scénario. P. Ovale partagerait un ancêtre commun le plus récent avec un Plasmodium de chimpanzé. Enfin, les grands singes africains se sont révélés de potentiels réservoirs pour trois des quatre espèces plasmodiales infectant l’homme (P. Falciparum, P. Ovale et P. Malariae)This thesis contributes, in using morphological, molecular and phylogenetic aspects to a better understanding of the Haemosporidian parasite diversity in vertebrate classes of birds, reptiles and mammals in two biodiversity hot spots, Madagascar and Cambodia. An atlas of Haemosporidia in wildlife of Madagascar and Cambodia has been realised to make available these data for public use. The parasites isolated have been characterized and identified with four molecular markers (cyt b, tufA, ldh and cox 1). The phylogenetic signal of each molecular marker has been evaluated. The mitochondrial genes, cyt b and cox 1 could carry a phylogenetic signal sufficient to conduct phylogenetic tree analyses comparing to tufA apicoplaste gene and ldh nuclear gene. The phylogenetic analyses highlighted host switches events between two vertebrate host classes, birds and mammals (bats). A co-evolutionary host parasite scenario bas been proposed for primate Plasmodium (including P. Falciparum in human) and Hominidae host family. A estimation of the emergence of P. Falciparum between 7 and 9 millions years has been deduced from this evolutionary scenario. P. Ovale would share a most recent common ancestor with a chimpanzee Plasmodium. Finally, greats apes could appear as a potential reservoirs for three of the four human Plasmodium (P. Falciparum, P. Ovale et P. Malariae)
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Rahbany, Nancy. « Towards integrated optics at the nanoscale : plasmon-emitter coupling using plasmonic structures ». Thesis, Troyes, 2016. http://www.theses.fr/2016TROY0003/document.
Texte intégralRésumé :
L'objectif de ce travail de thèse est d'étudier le couplage plasmon-émetteur dans des structures plasmoniques hybrides, visant à renforcer l’interaction lumière-matière à l'échelle nanométrique. Contrairement aux cavités optiques dont le volume de modes est limité par la diffraction, les cavités plasmoniques offrent un unique avantage d’efficacité du confinement sub-longueur d'onde. Cela peut conduire à l’accroissement de la fluorescence des émetteurs placés dans leur voisinage. Pour cela, nous proposons comme dispositif de focalisation une structure intégrée d’un réseau annulaire avec des nanoantennes afin de garantir une meilleure efficacité. Ce dispositif bénéficie du couplage entre des plasmons polaritons de surface (SPP) qui se propagent à partir du réseau et des plasmons localisés de surface (LSP) localisés aux niveaux des nanoantennes afin de parvenir à une augmentation de champ plus élevée. Nous présentons une étude de caractérisation de la plate-forme plasmonique constitué du réseau de diffraction métallique annulaire, d’une nanoantenne en étoile, et la structure intégrée réseau/nanoantenne. Nous montrons comment cette structure peut conduire à une plus grande émission des molécules de colorants ainsi que de centre SiV du diamant. La combinaison du confinement sub-longueur d'onde des LSP et l'énergie élevé des SPP dans notre structure conduit à une focalisation précise qui peut être mis en œuvre pour étudier le couplage plasmon-émetteur dans les régimes de couplage faibles et fortsThere is a growing interest nowadays in the study of strong light-matter interaction at the nanoscale, specifically between plasmons and emitters. Researchers in the fields of plasmonics, nanooptics and nanophotonics are constantly exploring new ways to control and enhance surface plasmon launching, propagation, and localization. Moreover, emitters placed in the vicinity of metallic nanoantennas exhibit a fluorescence rate enhancement due to the increase in the electromagnetic field confinement. However, numerous applications such as optical electronics, nanofabrication and sensing devices require a very high optical resolution which is limited by the diffraction limit. Targeting this problem, we introduce a novel plasmonic structure consisting of nanoantennas integrated in the center of ring diffraction gratings. Propagating surface plasmon polaritons (SPPs) are generated by the ring grating and couple with localized surface plasmons (LSPs) at the nanoantennas exciting emitters placed in the gap. We provide a thorough characterization of the optical properties of the simple ring grating structure, the double bowtie nanoantenna, and the integrated ring grating/nanoantenna structure, and study the coupling with an ensemble of molecules as well as single SiV centers in diamond. The combination of the sub-wavelength confinement of LSPs and the high energy of SPPs in our structure leads to precise nanofocusing at the nanoscale, which can be implemented to study plasmon-emitter coupling in the weak and strong coupling regimes
Livres sur le sujet "Plasmodi"
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Surface plasmon resonance : Methods and protocols. New York : Humana Press, 2010.
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Sönnichsen, Carsten. Plasmons in metal nanostructures. Göttingen : Cuvillier, 2001.
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Tolmasky, Marcelo E., et Juan C. Alonso, dir. Plasmids. Washington, DC, USA : ASM Press, 2015. http://dx.doi.org/10.1128/9781555818982.
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Gric, Tatjana. Spoof Plasmons. Cham : Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-031-02023-0.
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Zhang, Zhenglong. Plasmonic Photocatalysis. Singapore : Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-5188-6.
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Zhang, John X. J. Plasmonic MEMS. Cham : Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-23137-7.
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Bacterial plasmids. 2e éd. Wokingham, Berkshire, England : Van Nostrand Reinhold (UK), 1986.
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V, Klimov V. Nanoplazmonika. Moskva : Fizmatlit, 2010.
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1957-, Shalaev Vladimir M., dir. Nanoplasmonics. Amsterdam : Elsevier, 2006.
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Funnell, Barbara E., et Gregory J. Phillips, dir. Plasmid Biology. Washington, DC, USA : ASM Press, 2004. http://dx.doi.org/10.1128/9781555817732.
Texte intégralChapitres de livres sur le sujet "Plasmodi"
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Whetzel, Patricia L., Shailesh V. Date, Kobby Essien, Martin J. Fraunholz, Bindu Gajria, Gregory R. Grant, John Iodice et al. « PlasmoDB : The Plasmodium Genome Resource ». Dans Molecular Approaches to Malaria, 12–23. Washington, DC, USA : ASM Press, 2014. http://dx.doi.org/10.1128/9781555817558.ch2.
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Tatsuma, Tetsu. « Plasmonic Electrochemistry (Surface Plasmon Effect) ». Dans Encyclopedia of Applied Electrochemistry, 1591–94. New York, NY : Springer New York, 2014. http://dx.doi.org/10.1007/978-1-4419-6996-5_496.
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Schüffler, Anja, et Corinna Kübler. « Targeting Plasmids : New Ways to Plasmid Curing ». Dans Host - Pathogen Interaction, 179–200. Weinheim, Germany : Wiley-VCH Verlag GmbH & Co. KGaA, 2016. http://dx.doi.org/10.1002/9783527682386.ch10.
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Dostalek, Jakub. « Plasmonic Amplification for Fluorescence Bioassays Utilizing Propagating Surface Plasmons ». Dans Encyclopedia of Nanotechnology, 1–11. Dordrecht : Springer Netherlands, 2015. http://dx.doi.org/10.1007/978-94-007-6178-0_100986-1.
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Dostalek, Jakub. « Plasmonic Amplification for Fluorescence Bioassays Utilizing Propagating Surface Plasmons ». Dans Encyclopedia of Nanotechnology, 3277–86. Dordrecht : Springer Netherlands, 2016. http://dx.doi.org/10.1007/978-94-017-9780-1_100986.
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Kado, Clarence I. « Historical Events That Spawned the Field of Plasmid Biology ». Dans Plasmids, 1–11. Washington, DC, USA : ASM Press, 2015. http://dx.doi.org/10.1128/9781555818982.ch1.
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Hernández-Arriaga, Ana María, Wai Ting Chan, Manuel Espinosa et Ramón Díaz-Orejas. « Conditional Activation of Toxin-Antitoxin Systems : Postsegregational Killing and Beyond ». Dans Plasmids, 175–92. Washington, DC, USA : ASM Press, 2015. http://dx.doi.org/10.1128/9781555818982.ch10.
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Volante, Andrea, Nora E. Soberón, Silvia Ayora et Juan C. Alonso. « The Interplay between Different Stability Systems Contributes to Faithful Segregation : Streptococcus pyogenes pSM19035 as a Model ». Dans Plasmids, 193–207. Washington, DC, USA : ASM Press, 2015. http://dx.doi.org/10.1128/9781555818982.ch11.
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Samson, Julie E., Alfonso H. Magadan et Sylvain Moineau. « The CRISPR-Cas Immune System and Genetic Transfers : Reaching an Equilibrium ». Dans Plasmids, 209–18. Washington, DC, USA : ASM Press, 2015. http://dx.doi.org/10.1128/9781555818982.ch12.
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de Toro, María, M. Pilar Garcillán-Barcia et Fernando de la Cruz. « Plasmid Diversity and Adaptation Analyzed by Massive Sequencing of Escherichia coli Plasmids ». Dans Plasmids, 219–35. Washington, DC, USA : ASM Press, 2015. http://dx.doi.org/10.1128/9781555818982.ch13.
Texte intégralActes de conférences sur le sujet "Plasmodi"
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Yu, Min-Wen, Satoshi Ishii, Shisheng Li, Ji-Ren Ku, Jhen-Hong Yang, Kuan-Lin Su, Takaaki Taniguchi, Tadaaki Nagao et Kuo-Ping Chen. « Observation of carrier transports at exciton-plasmon coupling in MoS2 monolayers and 1D plamsmonic nanogrooves ». Dans JSAP-OSA Joint Symposia. Washington, D.C. : Optica Publishing Group, 2021. http://dx.doi.org/10.1364/jsap.2021.10a_n404_6.
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Two-dimensional transition metal dichalcogenides (TMDCs) have studied intensively owing to their unique optical and electronic properties [1]. Among TMDCs, monolayer molybdenum disulfide (MoS2) is a direct bandgap semiconductor with strong binding energies which make it as a perfect candidate for light-matter coupling system. In the current work, we fabricated hybrid systems of MoS2 monolayers [2] and 1D plasmonic nanogrooves made of gold (Au) to study exciton-plasmon coupling, particularly the carrier transport at the coupling state (see Fig. 1(a)). The nanogrooves were suited to excite in-plane plasmons, which are different from metallic-nanoparticle-on-mirror configuration.(/p)(p)The exciton-plasmon couplings were confirmed by the reflectance measurements and the dispersion relations were plotted from the reflectance measurements as shown in Fig. 1(b). In Fig. 1(b), the plasmon-exciton coupling of the upper polariton and lower polariton were plotted as a function of detuning. The splitting energy was as large as 65 meV, which is one of the largest among the values reported so far at room temperature. The exciton-plasmon coupling has also been confirmed by the Kelvin probe force microscope (KPFM) which recorded the surface potentials. As shown in Fig. 1(c), while there was no surface potential change for the MoS2 on planar Au film, a surface potential shift of 13.5 meV was observed for the MoS2 on nanogroove upon laser irradiation at 532 nm. This is a direct evidence that surface potential shift was induced at the exciton-plasmon coupling. Our results indicated that the 1D plasmonic nanogrooves are appropriate structures to study exciton-plasmon coupling with large splitting energy at room temperature.
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Srituravanich, W., N. Fang, C. Sun, S. Durant, M. Ambati et X. Zhang. « Plasmonic Lithography ». Dans ASME 2004 3rd Integrated Nanosystems Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/nano2004-46023.
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As the next-generation technology moves below 100 nm mark, the need arises for a capability of manipulation and positioning of light on the scale of tens of nanometers. Plasmonic optics opens the door to operate beyond the diffraction limit by placing a sub-wavelength aperture in an opaque metal sheet. Recent experimental works [1] demonstrated that a giant transmission efficiency (>15%) can be achieved by exciting the surface plasmons with artificially displaced arrays of sub-wavelength holes. Moreover the effectively short modal wavelength of surface plasmons opens up the possibility to overcome the diffraction limit in the near-field lithography. This shows promise in a revolutionary high throughput and high density optical lithography. In this paper, we demonstrate the feasibility of near-field nanolithography by exciting surface plasmon on nanostructures perforated on metal film. Plasmonic masks of hole arrays and “bull’s eye” structures (single hole surrounded by concentric ring grating) [2] are fabricated using Focused Ion Beam (FIB). A special index matching spacer layer is then deposited onto the masks to ensure high transmissivity. Consequently, an I-line negative photoresist is spun on the top of spacer layer in order to obtain the exposure results. A FDTD simulation study has been conducted to predict the near field profile [3] of the designed plasmonic masks. Our preliminary exposure test using these hole-array masks demonstrated 170 nm period dot array patterns, well beyond the resolution limit of conventional lithography using near-UV wavelength. Furthermore, the exposure result obtained from the bull’s eye structures indicated the characteristics of periodicity and polarization dependence, which confirmed the contribution of surface plasmons.
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Nishijima, Yoshiaki. « Mid infrared plasmon metasurfaces for sensing applications ». Dans JSAP-OSA Joint Symposia. Washington, D.C. : Optica Publishing Group, 2018. http://dx.doi.org/10.1364/jsap.2018.19p_211b_13.
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Petoukhoff, Christopher E., Keshav M. Dani et Deirdre M. O’Carroll. « Ultrastrong Plasmon-Exciton Coupling between Ag Nanoparticles and Conjugated Polymers ». Dans JSAP-OSA Joint Symposia. Washington, D.C. : Optica Publishing Group, 2019. http://dx.doi.org/10.1364/jsap.2019.18p_e208_13.
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Strong light-matter interactions involving organic semiconductors are important for a number of technical applications, including low-threshold lasing [1] and room-temperature Bose-Einstein condensates [2]. Coupling between excitons in organic semiconductors and surface plasmons results in the formation of plasmon-exciton hybridized modes, which are observed as energetic splitting in the normal modes of the coupled system (i.e., Rabi splitting) [3]. Typically, excitons with narrow resonances, such as those found in. J-aggregates, are used to achieve strong coupling, where the rate of energy exchange between excitons and plasmons in the hybrid system exceeds the decay rates of the plasmons and excitons in the isolated systems. However, for many applications, including plasmon-enhanced photovoltaics, light- emitting diodes, and spasers, coupling between plasmons and excitons within conjugated polymers is of great interest [4-6].
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Takeuchi, Yuki, Kotaro Mukaiyama, Nobuyuki Takeyasu et Yasutaka Hanada. « Multi-photon induced plasmon chemical transformation for laser microfabrication ». Dans JSAP-OSA Joint Symposia. Washington, D.C. : Optica Publishing Group, 2019. http://dx.doi.org/10.1364/jsap.2019.18a_e208_6.
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Surface plasmon polaritons (SPPs) enable the light to confine to sub-wavelength space. Metallic nanostructure is often used for plasmonic device since plasmon resonance band is generally formed at visible regime. SPPs lead to several orders enhancement of incident light intensity at the metallic nanosurface. While this remarkable effect has been studied for useful application (e.g. SERS, TERS photoluminescence, etc.), it was found plasmon generated highly energetic carriers through Landau damping, referred as hot electrons and holes. The hot carrier induces chemical transformation of molecules at the plasmonic nanosurface. The fact chemically inert molecules reacted by hot carrier has been reported in the recent [1].
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Umakoshi, Takayuki, Yuika Saito et Prabhat Verma. « Metallic tips for efficient plasmon nanofocusing and advanced optical nano-imaging ». Dans JSAP-OSA Joint Symposia. Washington, D.C. : Optica Publishing Group, 2017. http://dx.doi.org/10.1364/jsap.2017.6a_a410_3.
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Plasmon nanofocusing, energy compression of propagating plasmons on a tapered metallic tip, is a promising tool for near-field scanning optical microscopy due to its unique properties such as background suppression and broadband property[1]. Although applications of plasmon nanofocusing has been still limited so far, it would make the plasmon-nanofocusing-based techniques more reliable and practical if an efficient fabrication method of metallic tips is established.
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Chiu, Min–Hsueh, et Jia-Han Li. « Effects of band shifting on permittivity of plasmonic material ». Dans JSAP-OSA Joint Symposia. Washington, D.C. : Optica Publishing Group, 2018. http://dx.doi.org/10.1364/jsap.2018.19p_211b_7.
Texte intégralRésumé :
In recent decades, plasmonic devices are widely interested because of the capability of subwavelength confinement. The plasmon phenomena is generated by oscillation of free charges in optical frequency. Hence, the metallic component is general used in plasmonic device. Metal provides large amount of free charges and the negative real part of permittivity, which is the essential property of plasmonic material. However, the loss of metal is critical issue of the devices, which occur from the interband transition in visible and ultra-violet range. Thence, the engineering of permittivity is the important topic for plasmonic devices.
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Nayak, (D) Deepak Ranjan, et Siva Umapathy. « Surface Enhanced Raman Spectroscopic Studies using Galvanic Nano-buds ». Dans JSAP-OSA Joint Symposia. Washington, D.C. : Optica Publishing Group, 2017. http://dx.doi.org/10.1364/jsap.2017.6a_a410_1.
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Raman spectroscopy has attracted considerable attention in analytical measurements but lacks the sensitivity due to low scattering cross section. However, surface enhanced Raman spectroscopy (SERS) has brought both specificity and sensitivity on the same platform. The specificity in SERS technique is largely owing to the unique vibrational frequency of the molecules giving rise to finger print like spectra. Sensitivity, however, is tailored from electric field enhancement in plasmonic nanostructure and fabrication of nanostructure for a specific wavelength. Control of size, shape of suitable plasmonic material and there by excitation of localized surface plasmon resonance of a metal nanoparticle or nanostructured surface is essential in understanding the fundamental process of SERS. Optical property of the surrounding medium has profound effect on the plasmonic response of the metal nanoparticles. Such type of interaction in SERS substrates, associated to plasmon-substrate interaction, brings out simple yet effective method to fabricate SERS substrate.
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Kuo, Chia-Wen, Sheng-Han Wang, Shu-Cheng Lo, Ya-Lun Ho, Jean-Jacques Delaunay et Pei-Kuen Wei. « Sensitive Small Molecule Detection Using Coupling of Image Dipoles of Gold Nanoparticles and Fano Resonance of Periodic Gold Nanostructures ». Dans JSAP-OSA Joint Symposia. Washington, D.C. : Optica Publishing Group, 2021. http://dx.doi.org/10.1364/jsap.2021.10p_n404_11.
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Kondo, Masaki, et Wakana Kubo. « Photo Thermoelectric Effect Triggered by Local Heat under Localized Surface Plasmons ». Dans JSAP-OSA Joint Symposia. Washington, D.C. : Optica Publishing Group, 2018. http://dx.doi.org/10.1364/jsap.2018.19a_211b_6.
Texte intégralRésumé :
Heat generation in metallic nanostructure under plasmon is known as plasmonic local heat, and it has been utilized in various applications, for example, cancer therapy, photohermal chemistry, nanowire growth, and so on [1]. G. Baffou et al. reported that Au single nanoparticle generates local heat about 90 K under the light irradiation of 100 mW/cm2 [2]. These facts indicate plasmonic nanostructures will be effective nano-heaters.
Rapports d'organisations sur le sujet "Plasmodi"
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Coons, Terry. Restriction mapping and expression of recombinant plasmids containing the arsenic resistance genes of the plasmid R45. Portland State University Library, janvier 2000. http://dx.doi.org/10.15760/etd.5481.
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Mirkin, Chad. Plasmonic Encoding. Fort Belvoir, VA : Defense Technical Information Center, octobre 2014. http://dx.doi.org/10.21236/ada614625.
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3
Passmore, Brandon Scott, Eric Arthur Shaner et Todd A. Barrick. Plasmonic filters. Office of Scientific and Technical Information (OSTI), septembre 2009. http://dx.doi.org/10.2172/973849.
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Peale, Robert E. Plasmonic-Electronic Transduction. Fort Belvoir, VA : Defense Technical Information Center, janvier 2012. http://dx.doi.org/10.21236/ada566284.
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Alivisatos, A. P., Gabor A. Somorjai et Peidong Yang. Plasmonic-Enhanced Catalysis. Fort Belvoir, VA : Defense Technical Information Center, mai 2012. http://dx.doi.org/10.21236/ada576759.
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Jin, Rongchao. On the Evolution from Non-Plasmonic Metal Nanoclusters to Plasmonic Nanocrystals. Fort Belvoir, VA : Defense Technical Information Center, septembre 2014. http://dx.doi.org/10.21236/ada611094.
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Samtaney, R., N. F. Loureiro, D. A. Uzdensky, A. A. Schekochihin et S. C. Cowley. Formation of Plasmoid Chains in Magnetic Reconnection. Office of Scientific and Technical Information (OSTI), septembre 2009. http://dx.doi.org/10.2172/965277.
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Polyakov, Aleksandr. Plasmon Enhanced Photoemission. Office of Scientific and Technical Information (OSTI), mai 2012. http://dx.doi.org/10.2172/1182733.
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Atwater, Harry A. Plasmonic Devices and Materials. Fort Belvoir, VA : Defense Technical Information Center, juin 2005. http://dx.doi.org/10.21236/ada442370.
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Hasselbeck, M. P., L. A. Schlie et D. Stalnaker. Coherent Plasmons in InSb. Fort Belvoir, VA : Defense Technical Information Center, janvier 2004. http://dx.doi.org/10.21236/ada430825.
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