Bibliografias temáticas / Molecular machines and motors

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Literatura científica selecionada sobre o tema "Molecular machines and motors"

Autor: Grafiati

Publicado: 23 de novembro de 2024

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Artigos de revistas sobre o assunto "Molecular machines and motors"

Endow, Sharyn A. "Kinesin motors as molecular machines". BioEssays 25, n.º 12 (17 de novembro de 2003): 1212–19. http://dx.doi.org/10.1002/bies.10358.

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Kistemaker, Jos C. M., Anouk S. Lubbe e Ben L. Feringa. "Exploring molecular motors". Materials Chemistry Frontiers 5, n.º 7 (2021): 2900–2906. http://dx.doi.org/10.1039/d0qm01091j.

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The introduction of mechanical functions and controlled motion based on molecular motors and machines offers tremendous opportunities towards the design of dynamic molecular systems and responsive materials.

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Kay, Euan R, David A Leigh e Francesco Zerbetto. "Synthetic Molecular Motors and Mechanical Machines". Angewandte Chemie International Edition 46, n.º 1-2 (janeiro de 2007): 72–191. http://dx.doi.org/10.1002/anie.200504313.

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Kay, Euan R., e David A. Leigh. "Beyond switches: Rotaxane- and catenane-based synthetic molecular motors". Pure and Applied Chemistry 80, n.º 1 (1 de janeiro de 2008): 17–29. http://dx.doi.org/10.1351/pac200880010017.

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Nature uses molecular motors and machines in virtually every significant biological process, but learning how to design and assemble simpler artificial structures that function through controlled molecular-level motion is a major challenge for contemporary physical science. The established engineering principles of the macroscopic world can offer little more than inspiration to the molecular engineer who creates devices for an environment where everything is constantly moving and being buffeted by other atoms and molecules. Rather, experimental designs for working molecular machines must follow principles derived from chemical kinetics, thermodynamics, and nonequilibrium statistical physics. The remarkable characteristics of interlocked molecules make them particularly useful for investigating the control of motion at the molecular level. Yet, the vast majority of synthetic molecular machines studied to date are simple two-state switches. Here we outline recent developments from our laboratory that demonstrate more complex molecular machine functions. This new generation of synthetic molecular machines can move continuously and progressively away from equilibrium, and they may be considered true prototypical molecular motors. The examples discussed exemplify two, fundamentally different, "Brownian ratchet" mechanisms previously developed in theoretical statistical physics and realized experimentally in molecular-level devices for the first time in these systems.

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Credi, Alberto, e Margherita Venturi. "Molecular machines operated by light". Open Chemistry 6, n.º 3 (1 de setembro de 2008): 325–39. http://dx.doi.org/10.2478/s11532-008-0033-4.

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AbstractThe bottom-up construction and operation of machines and motors of molecular size is a topic of great interest in nanoscience, and a fascinating challenge of nanotechnology. Researchers in this field are stimulated and inspired by the outstanding progress of molecular biology that has begun to reveal the secrets of the natural nanomachines which constitute the material base of life. Like their macroscopic counterparts, nanoscale machines need energy to operate. Most molecular motors of the biological world are fueled by chemical reactions, but research in the last fifteen years has demonstrated that light energy can be used to power nanomachines by exploiting photochemical processes in appropriately designed artificial systems. As a matter of fact, light excitation exhibits several advantages with regard to the operation of the machine, and can also be used to monitor its state through spectroscopic methods. In this review we will illustrate the design principles at the basis of photochemically driven molecular machines, and we will describe a few examples based on rotaxane-type structures investigated in our laboratories.

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Dunn, K. E., M. C. Leake, A. J. M. Wollman, M. A. Trefzer, S. Johnson e A. M. Tyrrell. "An experimental study of the putative mechanism of a synthetic autonomous rotary DNA nanomotor". Royal Society Open Science 4, n.º 3 (março de 2017): 160767. http://dx.doi.org/10.1098/rsos.160767.

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DNA has been used to construct a wide variety of nanoscale molecular devices. Inspiration for such synthetic molecular machines is frequently drawn from protein motors, which are naturally occurring and ubiquitous. However, despite the fact that rotary motors such as ATP synthase and the bacterial flagellar motor play extremely important roles in nature, very few rotary devices have been constructed using DNA. This paper describes an experimental study of the putative mechanism of a rotary DNA nanomotor, which is based on strand displacement, the phenomenon that powers many synthetic linear DNA motors. Unlike other examples of rotary DNA machines, the device described here is designed to be capable of autonomous operation after it is triggered. The experimental results are consistent with operation of the motor as expected, and future work on an enhanced motor design may allow rotation to be observed at the single-molecule level. The rotary motor concept presented here has potential applications in molecular processing, DNA computing, biosensing and photonics.

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Siletti, Kimberly. "Roop Mallik: From machines to molecular motors". Journal of Cell Biology 216, n.º 4 (27 de março de 2017): 852–53. http://dx.doi.org/10.1083/jcb.201703074.

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Tafoya, Sara, e Carlos Bustamante. "Molecular switch-like regulation in motor proteins". Philosophical Transactions of the Royal Society B: Biological Sciences 373, n.º 1749 (7 de maio de 2018): 20170181. http://dx.doi.org/10.1098/rstb.2017.0181.

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Motor proteins are powered by nucleotide hydrolysis and exert mechanical work to carry out many fundamental biological tasks. To ensure their correct and efficient performance, the motors' activities are allosterically regulated by additional factors that enhance or suppress their NTPase activity. Here, we review two highly conserved mechanisms of ATP hydrolysis activation and repression operating in motor proteins—the glutamate switch and the arginine finger—and their associated regulatory factors. We examine the implications of these regulatory mechanisms in proteins that are formed by multiple ATPase subunits. We argue that the regulatory mechanisms employed by motor proteins display features similar to those described in small GTPases, which require external regulatory elements, such as dissociation inhibitors, exchange factors and activating proteins, to switch the protein's function ‘on’ and ‘off'. Likewise, similar regulatory roles are taken on by the motor's substrate, additional binding factors, and even adjacent subunits in multimeric complexes. However, in motor proteins, more than one regulatory factor and the two mechanisms described here often underlie the machine's operation. Furthermore, ATPase regulation takes place throughout the motor's cycle, which enables a more complex function than the binary ‘active' and ‘inactive' states. This article is part of a discussion meeting issue ‘Allostery and molecular machines'.

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Li, Dongbo, Walter F. Paxton, Ray H. Baughman, Tony Jun Huang, J. Fraser Stoddart e Paul S. Weiss. "Molecular, Supramolecular, and Macromolecular Motors and Artificial Muscles". MRS Bulletin 34, n.º 9 (setembro de 2009): 671–81. http://dx.doi.org/10.1557/mrs2009.179.

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AbstractRecent developments in chemical synthesis, nanoscale assembly, and molecular-scale measurements enable the extension of the concept of macroscopic machines to the molecular and supramolecular levels. Molecular machines are capable of performing mechanical movements in response to external stimuli. They offer the potential to couple electrical or other forms of energy to mechanical action at the nano- and molecular scales. Working hierarchically and in concert, they can form actuators referred to as artificial muscles, in analogy to biological systems. We describe the principles behind driven motion and assembly at the molecular scale and recent advances in the field of molecular-level electromechanical machines, molecular motors, and artificial muscles. We discuss the challenges and successes in making these assemblies work cooperatively to function at larger scales.

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Beeby, Morgan. "The bacterial flagellar motor and the evolution of molecular machines". Biochemist 40, n.º 2 (1 de abril de 2018): 4–9. http://dx.doi.org/10.1042/bio04002004.

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Understanding how life on earth evolved is an enduringly fascinating and profound question. Relative to our understanding of eukaryotic evolution, however, our understanding of how the molecular machines underpinning life have evolved is poor. The bacterial flagellar motor, which drives a rotary propeller for motility, offers a fascinating case study to explore this further, and is now revealing recurring themes in molecular evolution. This article describes recent discoveries about how flagellar motors have diversified since the first flagellar motor evolved, and what this diversity tells us about molecular evolution.

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Mais fontes

Teses / dissertações sobre o assunto "Molecular machines and motors"

Li, Quan. "Integrated motions of light driven molecular motors at macroscopic scale". Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAF001/document.

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Dans la nature, des moteurs moléculaires tells que l'ATP synthase ou la kinésine peuvent consommer de l'énergie pour générer du mouvement et ainsi assurer des fonctions essentielles comme le transport ou la synthèse de molécules. La préparation de moteurs artificiels capables de fournir un travail à différentes échelles est un défi important pour les chimistes. Dans ce travail, nous avons conçu et synthétisé de manière stéréosélective un moteur moléculaire unidirectionnel et hautement fonctionnalisé à l'échelle du gramme. La fonctionnalisation orthogonale du moteur permet de l'intégrer dans des matériaux polymères. Grâce à une réaction de "click" réalisée sous différentes conditions de dilution, nous avons pu obtenir soit une macromolécule bicyclique en forme de 8 soit un gel de polymers dont les moteurs constituent les points de réticulation. Sous irradiation UV, les moteurs tournent ce qui enroule les chaines de polymers. Pour le bicycle, la taille caractéristique de la macromolécule diminue tandis que la morphologie évolue vers une pelote étirée. Dans le cas du gel, suite à la rotation des moteurs, l'enroulement des chaines conduit à une contraction du gel de l'ordre de 80% en volume. C'est le premier exemple d'intégration de mouvements moléculaires hors équilibre résultant en une réponse observable à l'échelle macroscopique. Ce travail ouvre des perspectives intéressantes dans le domaine des nanotechnologies ainsi que dans celui de l'énergie
Natural molecular motors such as ATP synthase, myosin, kinesin and dynein can convert conformationalchanges, due to chemical energy input, into directed motion for catalysis and transport. Preparing artificial molecular motors and making them work at different scales (from nano to macroscopic scale) have been long-term challenges. Herein we designed and synthesized a light driven rotary molecular motor in highly enantiopure form and in gram scale. This motor is featured by two orthogonal functionalities on its upper and lower part, allowing its further integration into polymeric materials. By performing click reaction under different concentration conditions, either an eight shaped motor-polymer conjugate or a gel containing motors as reticulation units could be obtained. Upon UV irradiation, the polymer chains could be entangled due to the rotation of this motor. For eight shaped polymer, the dimension was changed towards smaller dimension, and the morphology was changed from cycle to collapsed coils (spherical or more elongated). For the gel, due to the twisting of polymer chains induced by the rotation of the motor, it could be contracted significantly (80 %) compared with its original volume. The integration of machines which display motions out of equilibrium at nanoscale to movement in the macroscopic world which is extensively used in natural systems will open very interesting prospects in nanotechnology for further developments

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Mendoza, Sandra Marina. "Exploiting molecular machines on surfaces". [S.l. : Groningen : s.n. ; University Library Groningen] [Host], 2007. http://irs.ub.rug.nl/ppn/304755133.

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Sasai, Masaki, Tomoki P. Terada e Mitsunori Takano. "Unidirectional Brownian motion observed in an in silico single molecule experiment of an actomyosin motor". National Academy of Sciences, 2010. http://hdl.handle.net/2237/20619.

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Goujon, Antoine. "Macroscopic amplification of nanoscopic motions induced by molecular machines". Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAF044/document.

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Ces vingt dernières années, le domaine du design et de la synthèse de machines moléculaires complexes a fait d’énormes progrès,souvent inspiré par la beauté de la machinerie présente dans les systèmes vivants. Cependant, l’amplification des mouvements d’un grand nombre de machines moléculaires à des échelles de tailles largement supérieures à leurs dimensions restent un défi théorique et expérimental ambitieux et ardu. Ce travail décrit comment l’organisation de machines et moteurs moléculaires dans des réseaux polymères supramoléculaires ou covalents permet de synthétiser des matériaux dans lesquels leurs mouvements individuels nanométriques sont amplifiés jusqu’à l’échelle macroscopique. Les trois premiers chapitres décrivent l’utilisation d’une architecture de type [c2]daisy chains, une molécule capable d’effectuer des contraction/extensions similaires aux mouvements des sarcomères présents dans les muscles, dans des réseaux polymères supramoléculaires et covalents. Leur introduction dans des polymères supramoléculaires à liaisons hydrogène basées sur le motif de reconnaissance uracil:2,6-diacetylaminopyridine associé à des interactions latérales tel que les interactions π résulta en la formation de fibre supramoléculaires contractiles dont la taille et la morphologie a pu être commuté entre deux états étendus et contractés. L’incorporation de motifs uréidopyrimidinone comme connecteur supramoléculaire en revanche donna accès à des gels supramoléculaires, évoluant vers un état liquide lors de la contraction des chaines polymères. Finalement, l’inclusion de daisy chains dans un réseau polymère 3D a donné accès à un gel chimique. Ce matériau a pu être contracté et étendu à l’échelle macroscopique grâce à l’action combinée des machines moléculaires le constituant.Le quatrième chapitre est dédié à l’amélioration d’un gel contractile basé sur l’utilisation de moteurs moléculaires rotatif comme noeud de réticulation d’un réseau polymère. Une unité modulatrice, capable d’être commuté entre un état “ouvert” et “fermé”, a été introduite dans le réseau aux côtés du moteur. Le modulateur dans son état “fermé” permet aux moteurs moléculaires de contracter efficacement le réseau, tandis que dans son état ouvert il permet aux chaines de se dérouler alors que le moteur ne tourne pas, ce qui provoque l’extension du réseau qui retourne à sa taille initiale. En résumé, le travail décrit dans ce manuscrit illustre que des machines moléculaires soigneusement conçue peuvent être introduites dans des réseaux polymères, fournissant des matériaux dont les propriétés macroscopiques sont affectées par les mouvements nanoscopiques de ses constituants. Ces résultats fournissent des pistes et une base fondamentale pour l’élaboration d’une nouvelle classe de matériaux contractiles basés sur des machines moléculaires
The last twenty years have seen tremendous progresses in the design and synthesis of complex molecular machines, often inspired by the beauty of the machinery found in biological systems. However, amplification of the molecular machines motion over several orders of magnitude above their typical length scale is still an ambitious challenge. This work describes how self-organization of molecular machines or motors allows for the synthesis of materials translating the motions of their components into a macroscopic response. The three first chapters describe the use of a [c2]daisy chains architecture, a molecule able to perform contraction/extension motions similarly to the sarcomere units of muscles, into systems such as supramolecular polymers and covalent networks. Their inclusion into hydrogen bonding supramolecular polymers based on the uracil:2,6-diacetylaminopyridine recognition motifs combined with lateral interactions such as π-stacking provided micrometric muscle-like fibers contracting and extending upon deprotonation and protonation.The incorporation of ureidopyrimidone moieties as supramolecular connectors yielded highly organized gels, which evolved to a liquidstate upon contraction of the polymer chains. Finally, covalent poly[c2]daisy chains were synthesized and investigated, notably the formation of a 3D network swelling into a gel. This material could contract and extend at the macroscopic scale upon contraction and extension of the molecular machines used as monomers. Finally, a fourth chapter is dedicated to the improvement of contractile chemical gels made by using a molecular motor as reticulating nodes. A modulating unit, able to be switched between a “closed” and an “opened” state, was introduced into the polymer network along with the motor. The locked structure in the “closed” state allowed contraction of the gel upon rotation of the molecular motors, while the “opened” state allowed unwinding of the entangled polymer chains and extension of the gel when the motor is off. Overall, the work presented in this manuscript demonstrates that carefully designed molecular machines can be incorporated into large supramolecular or covalent assemblies, providing materials which collective motions alter their macroscopic properties. These results provide valuable insights for the elaboration of a new class of muscle-like materials based on molecular machines

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Cherraben, Sawsen. "Machines moléculaires à base de cyclodextrines fonctionnalisées". Thesis, Sorbonne université, 2019. https://accesdistant.sorbonne-universite.fr/login?url=http://theses-intra.upmc.fr/modules/resources/download/theses/2019SORUS633.pdf.

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Le contrôle du mouvement et de sa directionnalité à l’échelle moléculaire est un défi actuel. Ce travail de thèse s’est intéressé à l’élaboration d’une famille de machines moléculaires à base de cyclodextrines (CDs). L’objectif a été d’exploiter l’asymétrie intrinsèque des CDs et de les fonctionnaliser sélectivement afin de pouvoir leur appliquer directement un stimulus. Nous pouvons dès lors contrôler leurs mouvements dans des architectures supramoléculaires. Dans une première approche, nous avons développé un commutateur pH-sensible de type pseudo-rotaxane à base de CDs sélectivement fonctionnalisées par des amines sur le col primaire. Un contrôle de l’enfilage et du désenfilage par un stimulus pH et une modulation de la cinétique de désenfilage par variation du nombre d’amines ont été obtenus. Dans une deuxième approche, nous avons conçu un système utilisant un carburant chimique pour obtenir un mouvement unidirectionnel par le transport actif d’une CD fonctionnalisée. Le point clé est l’étape de clivage de groupements protecteurs sur l’axe par la fonction catalytique portée par la CD, qui devrait avoir lieu préférentiellement par le col primaire et assurer son transport dirigé. Pour cela, un premier [2]rotaxane modèle de CDMe à trois stations a été synthétisé par une approche de post-fonctionnalisation d’un [2]rotaxane, avec des bouchons amides. Son étude a montré la formation de 3 mécano-isomères lors de la réaction de protection avec une distribution non-statistique indiquant un probable biais cinétique. Ces travaux prometteurs ouvrent des perspectives à plus long terme sur l’obtention de moteurs moléculaires à énergie chimique avec un transport actif de la CD
Controlling motion and directionality at the molecular level is a major challenge. This thesis project focused on the development of a family of cyclodextrin (CDs) based molecular machines. The objective was to exploit the inherent asymmetry of CDs and to functionalize them selectively in order to be able to apply a stimulus directly to them. Hence, controlling their movements in supramolecular architectures becomes possible. In the first approach, we developed a pH-sensitive switch of the pseudo-rotaxane type based on CDs selectively functionalized by amines on the primary rim. A remarkable control of threading and dethreading by a pH stimulus were obtained, along with a modulation of the dethreading kinetics by variation in the number of amines. In a second approach, we designed a system using a chemical fuel to obtain unidirectional motion of a functionalized CD through its active transport. The key step is the cleavage of protective groups located on the axis by the catalytic function carried by the CD, which should preferably take place through the primary rim, ensuring its directed transport. For this purpose, a first three-station [2]rotaxane CDMe model was synthesized by a post-functionalization approach of a one-station [2]rotaxane with amide stoppers. Its study showed the formation of 3 mechano-isomers during the protective reaction with a non-statistical distribution indicating a probable kinetic bias. This promising work opens up longer-term perspectives on the development of chemically fueled molecular motors with active CD transport

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Sirven, Agnès. "Nano-machines : vers la synthèse d'un treuil moléculaire". Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30200.

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Dans le domaine des nanomachines, des progrès considérables ont été réalisés. Il est désormais possible de synthétiser une machine moléculaire et de contrôler son mouvement grâce à une source d'énergie chimique, lumineuse ou électrique, de façon à ce qu'il soit unidirectionnel. Un nouveau défi a surgi : comment rendre ce mouvement utile ? Comment utiliser le travail d'une machine moléculaire au niveau nanoscopique, mésoscopique ou macroscopique ? Cette thèse s'inscrit à la suite de la démonstration du contrôle de la rotation d'un moteur moléculaire. Ce moteur est un complexe de ruthénium(II) dont la rotation de la partie mobile, le rotor, est contrôlée par la pointe d'un microscope à effet tunnel. Afin de déterminer le travail limite fournit par ce moteur, nous avons synthétisé un nanotreuil intégrant le moteur moléculaire déjà étudié dans l'équipe avec une chaîne latérale permettant d'accrocher par chimie clic différents types de fragments moléculaires. Ces fragments ayant des natures chimiques différentes (fullerènes, triptycènes, porphyrines), ils interagiront de manière plus ou moins importante avec la surface. De ce fait, la rotation du moteur pourra ou ne pourra pas entraîner leur déplacement sur la surface, ce qui nous permettra d'estimer le travail du moteur. Cette thèse décrit la synthèse des différentes sous-unités de ce nanotreuil : le moteur dissymétrique, la chaîne et les différentes charges. Après avoir développé différentes stratégies visant à intégrer la chaîne sur le rotor, la synthèse de chacun des fragments moléculaires fera l'objet des chapitres suivants. Enfin, un chapitre mettra en perspective l'intégration possible du moteur dans des systèmes d'engrenages en vue de la récupération du travail dans un réseau supramoléculaire
In the field of molecular machines, considerable developments have been achieved. Nowadays, it is possible to synthesize a molecular machine with a directional control on its motion thanks to chemical, light or electrical energy source. A new challenge has arised: how make that movement useful ? How use the work of a molecular machine at a nano-, meso- or macro-level ? This thesis is in line with the demonstration and control of the molecular motor rotation. This motor consists in a ruthenium(II) complexe whom rotation of the movable part, i.e. the rotor, is controlled by the scanning tunnelling microscope tip. In order to estimate its motive power, we have synthesized a nanowinch incorporating the molecular motor synthesized in the team. This motor has been desymmetrized to be able to incorporate a chain allowing to connect by click chemistry several kind of molecular fragments. These fragments (fullerenes, triptycenes, porphyrines) will interact more or less with the surface of deposition. Therefore, the motor rotation will or will not make them move on the surface, giving us the possibility to estimate the motor torque. In this thesis, the synthesis of the different parts of the nanowinch is described : the dissymmetric molecular motor, the linker and the loads. After developping the synthetic strategies allowing us to incorporate the linker on the rotor, the synthesis of each fragment will be detailled in the following chapters. A concluding chapter will deal with the possible integration of that type of complexes into molecular gears in order to exploit the torque in a supramolecular network

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Daou, Dania. "Intégration de moteurs moléculaires photoactivables dans des gels supramoléculaires". Electronic Thesis or Diss., Strasbourg, 2024. http://www.theses.fr/2024STRAF021.

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Cette thèse a exploré l'intégration de moteurs moléculaires synthétiques photoactivables dans des réseaux de gels supramoléculaires. L'objectif principal était d'obtenir un mouvement macroscopique réversible en exploitant à la fois la rotation unidirectionnelle des moteurs moléculaires et la nature réversible des interactions supramoléculaires. Des moteurs moléculaires hautement fonctionnalisés ont été synthétisés et intégrés comme unités de réticulation dans des réseaux de gel supramoléculaire de peptides de diphénylalanine et de poly(γ-benzyl-L-glutamate) et d'oligonucléotides d'ADN. L'activation de la rotation unidirectionnelle des moteurs moléculaires par la lumière a permis de produire un travail nanomécanique suffisant pour perturber les interactions supramoléculaires dans les réseaux de gel à base de peptides, ce qui entraîne la contraction ou la fonte du gel à l'échelle macroscopique. Grâce aux interactions supramoléculaires réversibles, le matériau gélifié initial a pu être récupéré dans l'obscurité, soit spontanément, soit par l'application d'un stimulus thermique. Les systèmes étudiés dans cette thèse représentent une nouvelle classe de matériaux fonctionnant dans des conditions dissipatives hors équilibre, promettant des applications dans divers domaines tels que la biologie, la médecine et la science des matériaux
This thesis explored the integration of light-driven synthetic molecular motors in supramolecular gel networks. The main goal was to achieve reversible macroscopic motion by exploiting both the unidirectional rotation of molecular motors and the reversible nature of supramolecular interactions. Highly functionalized molecular motors have been synthesized and integrated as crosslinking units in supramolecular gel networks of diphenylalanine and poly(γ- benzyl-L-glutamate) peptides, as well as DNA oligonucleotides. Activation of the unidirectional rotation of molecular motors by light, allowed the production of nanomechanical work which is sufficient to disrupt supramolecular interactions in peptide-based gel networks leading to contraction or melting of the gel material at the macroscopic scale. Thanks to the reversible supramolecular interactions, the initial gel material was recovered in the dark, either spontaneously or by applying a thermal stimulus. The systems studied in this thesis represent a novel class of materials operating in dissipative out-of-equilibrium conditions, holding promise of applications in various fields such as biology, medicine and material science

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Cox, Thomas. "Development of novel linear drive machines". Thesis, University of Bath, 2008. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.500760.

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Linear induction machines currently play a relatively minor role in the industrial world. This is partly due to relatively high production costs, complexity of construction and the Inability to apply standard mass production techniques. The aim of this thesis is to investigate the design of linear machines that are cheaper and faster to produce, and that may easily be mass-produced This thesis principally concerns the use of concentrated winding linear stators. These are cheap and easy to manufacture and can be easily mass-produced. However, high levels of negative harmonics make them unsuitable for use with simple sheet rotors.

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Göl, Özdemir. "Dynamic modelling of induction machines /". Title page, contents and abstract only, 1993. http://web4.library.adelaide.edu.au/theses/09PH/09phg595.pdf.

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Hanekom, Alwyn Nicolaas. "A torque ripple analysis on reluctance synchronous machines". Thesis, Cape Peninsula University of Technology, 2006. http://hdl.handle.net/20.500.11838/1145.

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Thesis MTech(Electrical Engineering))--Cape Peninsula University of Technology, 2006
Reluctance Synchronous Machines (RSM) have, due to their rotor geometry, an inherently high torque ripple. This torque ripple is defined as the deviation of the minimum and maximum torque from the average value. It is unwanted as it indicates uneven pull on the rotor causing deformation of it and hence different air-gaps along the rotor circumference as well as acoustic noise. In applications such as power steering, robotics and radar positioning systems where high precision movement is vital, oscillating torque will lead to the malfunction of these devices and therefore suppressed the use and development of RSMs. Unlike the Induction machine (IM), the RSM has no copper losses in the rotor, which reduces the operating temperature significantly. With the development of electronic drives the quality of the output torque could be improved by means of accurate current- and flux space phasor control methods with much success and made the RSM a possible replacement for the IM. However, reducing torque ripple by means of purely geometrical changes is still a challenge to the machine designer. This thesis will focus on the reduction of torque ripple while leaving the average torque relatively unchanged by changing the rotor geometry. The rotor changes will take place by means of flux barriers and cut-outs while the stator has either semi-closed slots or magnetic wedges. In this work rotor structures with equal harmonic magnitudes but their angles 1800 apart. will be combined to form one machine and identify how torque harmonics respond. The change in average torque and power factor will be evaluated with all geometrical changes made to these machines throughout this work.

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Mais fontes

Livros sobre o assunto "Molecular machines and motors"

Jean-Pierre, Sauvage, e Amendola V, eds. Molecular machines and motors. Berlin: Springer, 2001.

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Credi, Alberto, Serena Silvi e Margherita Venturi, eds. Molecular Machines and Motors. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-08678-1.

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Sauvage, Jean-Pierre, V. Amendola, R. Ballardini, V. Balzani, A. Credi, L. Fabbrizzi, M. T. Gandolfi et al., eds. Molecular Machines and Motors. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/3-540-44421-1.

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Joachim, Christian, e Gwénaël Rapenne, eds. Single Molecular Machines and Motors. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-13872-5.

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Ann, Sperry O. Molecular Motors. New Jersey: Humana Press, 2007. http://dx.doi.org/10.1385/1597454907.

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Sperry, Ann O., ed. Molecular Motors. Totowa, NJ: Humana Press, 2007. http://dx.doi.org/10.1007/978-1-59745-490-2.

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Lavelle, Christophe, ed. Molecular Motors. New York, NY: Springer New York, 2018. http://dx.doi.org/10.1007/978-1-4939-8556-2.

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1945-, Schliwa M., ed. Molecular motors. Weinheim: Wiley-VCH, 2003.

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name, No. Molecular motors. Weinheim: Wiley-VCH, 2003.

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George, Banting, Higgins S. J e Biochemical Society (Great Britain), eds. Molecular motors. London: Portland Press, 2000.

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Capítulos de livros sobre o assunto "Molecular machines and motors"

Rapenne, Gwénaël, e Christian Joachim. "Single Rotating Molecule-Machines: Nanovehicles and Molecular Motors". In Molecular Machines and Motors, 253–77. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/128_2013_510.

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Leigh, David A., Urszula Lewandowska, Bartosz Lewandowski e Miriam R. Wilson. "Synthetic Molecular Walkers". In Molecular Machines and Motors, 111–38. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/128_2014_546.

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Hashidzume, Akihito, Hiroyasu Yamaguchi e Akira Harada. "Cyclodextrin-Based Molecular Machines". In Molecular Machines and Motors, 71–110. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/128_2014_547.

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Silvi, Serena, e Alberto Credi. "Molecular Motors and Machines". In Nanotechnology for Biology and Medicine, 71–100. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-0-387-31296-5_4.

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Wang, Fuan, Bilha Willner e Itamar Willner. "DNA-Based Machines". In Molecular Machines and Motors, 279–338. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/128_2013_515.

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Liu, Jian, Marielle Gómez-Kaifer e Angel E. Kaifer. "Switchable Molecular Devices: From Rotaxanes to Nanoparticles". In Molecular Machines and Motors, 141–62. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/3-540-44421-1_6.

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Duwez, Anne-Sophie. "Single-Molecule Measurements of Synthetic Molecular Machines at Work". In Single Molecular Machines and Motors, 1–16. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-13872-5_1.

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Credi, Alberto, Serena Silvi e Margherita Venturi. "Light-Operated Machines Based on Threaded Molecular Structures". In Molecular Machines and Motors, 1–34. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/128_2013_509.

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Cnossen, Arjen, Wesley R. Browne e Ben L. Feringa. "Unidirectional Light-Driven Molecular Motors Based on Overcrowded Alkenes". In Molecular Machines and Motors, 139–62. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/128_2013_512.

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Zhao, Ke, Paul I. Dron, Jiří Kaleta, Charles T. Rogers e Josef Michl. "Arrays of Dipolar Molecular Rotors in Tris(o-phenylenedioxy)cyclotriphosphazene". In Molecular Machines and Motors, 163–211. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/128_2013_513.

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Trabalhos de conferências sobre o assunto "Molecular machines and motors"

Rapenne, Gwenael. "Invited: Prototypes of molecular machines: motors, gears and vehicles". In 2021 IEEE International Meeting for Future of Electron Devices, Kansai (IMFEDK). IEEE, 2021. http://dx.doi.org/10.1109/imfedk53601.2021.9637563.

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Walcott, Sam, e Neil M. Kad. "Theoretical Prediction of Run Speed Distribution for a Molecular Motor". In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-68761.

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Processive molecular motors are large proteins that “walk” along filaments in a cell, transforming chemical energy into mechanical work. These microscopic motors behave, at least qualitatively, like macroscopic walking machines. The dynamics and stability of macroscopic walkers are understood by analysis of “stride functions” (Poincare´ maps from one step to the next). We show that molecular motors have linear, probabilistic stride functions. Using these functions, we derive expressions for three measurable distributions: step period, run length and average run speed. The former two distributions are well known, the latter is new. We validate our calculation with simulations of a realistic model for Myosin Va (a molecular motor). The parameters of the run speed distribution specify both the run-length and step period distributions. As step-period distributions are difficult to measure under physiologically relevant conditions, this technique provides new information. Finally, we discuss the effects of variable step size and experimental error.

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Pshenichnikov, Maxim S., Nong V. Hoang, Lukas Pfeifer, Stefano Crespi e Ben L. Feringa. "Two-in-One: Rotation and Photoluminescence Dynamics of Artificial Molecular Motors". In International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/up.2022.tu1a.3.

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We present dynamics of the first prototype of artificial molecular motors exhibiting the dual function of rotary motion and photoluminescence. This provides a non-invasive way to locate and operate these machines in complex (bio)environments.

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Culver, Dean, Bryan Glaz e Samuel Stanton. "A Dynamic Escape Problem of Molecular Motors". In ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-88612.

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Animal skeletal muscle exhibits very interesting behavior at near-stall forces (when the muscle is loaded so strongly that it can barely contract). Near this physical limit, the actinmyosin cross bridges do more work than their energy releasing molecules, Adenosine TriPhosphate (ATP) suggest they can. It has been shown that the advantageous utilization of thermal agitation is a likely source for this increased capacity. Here, we propose a spatially two-dimensional mechanical model to illustrate how thermal agitation can be harvested for useful mechanical work in molecular machinery without rate functions or empirically-inspired spatial potential functions. Additionally, the model accommodates variable lattice spacing, and it paves the way for a full three dimensional model of cross-bridge interactions where myosin II may be azimuthally misaligned with actin binding sites. With potential energy sources based entirely on realizable components, this model lends itself to the design of artificial, molecular-scale motors.

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Teboul, Victor, Stephane Chaussedent e Nathalie Gaumer. "Fluidization and dynamic heterogeneity induced by molecular motor’s stimuli in soft matter". In Molecular and Nano Machines V, editado por Zouheir Sekkat e Takashige Omatsu. SPIE, 2022. http://dx.doi.org/10.1117/12.2635721.

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Hendricks, Adam G., Bogdan I. Epureanu e Edgar Meyho¨fer. "Synchronization of Motor Proteins Coupled Through a Shared Load". In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-15752.

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Kinesin-1 is a processive molecular motor that converts the energy from adenosine triphosphate (ATP) hydrolysis and thermal fluctuations into motion along microtubules. This motion can be interpreted as a result of ATP-fueled nonlinear nonsmooth oscillations of coupled motor domains which interact with a microtubule to transport a cargo. This class of nano-scale motors transport cargoes for distances of several micrometers in cells. This transport can also be achieved in vitro, opening the possibility of developing robust and extremely versatile nano-scale actuators or sensors based on the machinery used by biological systems. These devices could be used in a range of nano-scale applications such as drug delivery and lab-on-a-chip. However, to design such systems, a quantitative, in-depth understanding of molecular motors is essential. Single-molecule techniques have allowed the experimental characterization of kinesin-1 in vitro at a range of loads and ATP concentrations. Existing models of kinesin movement are stochastic in nature and are not well suited to describing transient dynamics. However, kinesin-1 is expected to undergo transient dynamics when external perturbations (e.g. interaction with other kinesin molecules) cause the load to vary in time. It is thought that in the cell, several kinesin motors work cooperatively to transport a common load. Thus, a transient description is integral to capturing kinesin behavior. This paper presents a mechanistic model that describes, deterministically, the average motion of kinesin-1. The structure of the kinesin-1 molecule is approximated with a simplified geometry, explicitly describing the coupling between its two heads. The diffusion is modeled using a novel approach based on the mean first-passage time, where the potential in which the free head diffuses is time varying and updated at each instant during the motion. The mechanistic model is able to predict existing force-velocity data over a wide range of ATP concentrations (including the interval 1μM to 10 mM). More importantly, the model provides a transient description, allowing predictions of kinesin-1 pulling time-varying loads and coordinated transport involving several kinesin-1 molecules. The deterministic approach is validated by comparing results to experiments and Monte Carlo simulations of the stochastic dynamics. Furthermore, using this model, the synchronization of several kinesin-1 molecules transporting a common load is investigated. Novel methods to characterize synchronization, tailored to the particularities of these nonsmooth systems, are presented.

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Nyquist, Roger, Mike Andrews, Andrew Hunter e Oyuna Myagmar. "Acceptance Testing of Liquefied Natural Gas Compressors". In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-43711.

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The majority of natural gas compressors operate on gas mixtures with molecular weights (MW) less than air. For these machines, performance acceptance tests are run on air at reduced speed. For multistage compressors, each stage is tested individually. The test speeds and inlet temperatures are selected to closely match the inlet to exit density ratios and the machine Mach numbers per the ASME PTC10 test code. The specified test inlet pressure (limited by the test variable speed motor power capacity) is always high enough to assure that the test Reynolds number is above the required PTC10 minimum; the density ratio and machine Mach number do not depend on inlet pressure. The air test data is converted to the specified natural gas conditions using similarity laws, and an in-house stage matching program is used to determine the overall machine performance. For compressors used in liquefied natural gas (LNG) transport, the MW of the natural gas mixture is lower than air. However, the inlet temperatures are so low that an air test at typical ambient temperatures needs to be run at a speed higher than design to closely match density and machine Mach number ratios. It is impractical to run air tests at higher than design speeds (especially for 60 Hz machines), thus these machines are tested on air at design speed. As before, the air test data is reduced to the specified natural gas conditions using the similarity laws. An additional “compressibility” correction is made to account for the mismatch of density ratio between test and design conditions. Running a test at lower than the required PTC10 speed means that the test density ratio will be lower than the corrected density ratio and the stage would pass more flow than the test data conversion indicates. The method used to account for the density ratio mismatch, i.e. a “compressibility” correction is discussed in detail in this paper.

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Simmel, Friedrich C., e Bernard Yurke. "DNA molecular motors". In SPIE's 8th Annual International Symposium on Smart Structures and Materials, editado por Anna-Maria R. McGowan. SPIE, 2001. http://dx.doi.org/10.1117/12.429683.

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Barhorst, A. A., O. P. Harrison e G. D. Bachand. "Modeling Elasto-Mechanical Phenomena Involved in the Motor-Driven Assembly of Nanomaterials". In ASME 2007 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/detc2007-34175.

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As the ability to manipulate materials and components at the nanoscale continues to grow, it will become increasingly critical to understand the dynamic interactions that occur among multiple components. For example, the dynamic interactions among proteins (i.e., nanoscale molecular machines) lead to complex, emergent behaviors such as photosynthesis, self-repair, and cell division. Recently, the research group at Sandia National Labs and The Center for Integrated Nanotechnologies (CINT), headed by George Bachand, has developed a molecular transport system capable of transporting and manipulating a wide range of nanoscale components. This system is based on the kinesin motor molecule and cytoskeletal filament microtubules (MTs), in which the kinesin are mounted to a substrate in an inverted fashion, and capable of binding and transporting the MTs across a surface as a molecular shuttle. In the presence of ATP, the kinesins are capable of generating ∼40 pN·nm of work, and transporting MTs along the substrate at velocities of ∼1 micro-m/sec. The MTs may also serve as a transport platform for various inorganic and biological nanoparticles. During transport, the cargo is transferred, via elastic collisions, from one MT to another or to where two MT carry a single cargo. Bending of the MT and various other elasto-dynamic phenomena such as particle ejection, MT sticking, etc are observed via fluorescence microscopy. The interaction observed by the Bachand team is not unlike the interaction of macroscale devices. The kinesin provide motivation to the MT via a hand-over-hand ratchet like motion driven by ATP hydrolysis. As the kinesin motor domains come into contact with and bind the MT, it is not inconceivable to think of this action from the framework of instantly applied constraints in a manner similar to the macroscopic action of devices coming into and out of constrained interaction. The hypothesis of our work is that the elasto-dynamic phenomenon observed can be modeled with the tools of multiple body dynamics modeling. The modeling perspective is based on the lead author’s hybrid parameter multiple body dynamics modeling methodology. This technique is a variational approach based on the projection methods of Gibbs-Appell. The constrained interaction through contact and impact are modeled with the idea of instantly applied non-holonomic constraints, where the interactions on the boundaries and in the domain of elastic continua are modeled via projections of the d’Alembert force deficit along conjugate directions generated via so called pseudo-generalized-speeds. In this paper we present motivation for our approach, the underlying modeling theory, and current results of our efforts at understanding the kinesin/MT shuttle system interaction.

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Feringa, Ben L. "Molecular switches and motors". In NOBEL SYMPOSIUM 153: NANOSCALE ENERGY CONVERTERS. AIP, 2013. http://dx.doi.org/10.1063/1.4794713.

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Relatórios de organizações sobre o assunto "Molecular machines and motors"

Li, Quan. Light-Driven Chiral Molecular Motors for Passive Agile Filters. Fort Belvoir, VA: Defense Technical Information Center, maio de 2014. http://dx.doi.org/10.21236/ada605831.

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Montemagno, Carlo. Development of a Generator to Power ATP-Driven Molecular Motors. Office of Scientific and Technical Information (OSTI), outubro de 2002. http://dx.doi.org/10.2172/900245.

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Summers, Anne O. Integrating the Molecular Machines of Mercury Detoxification into Host Cell Biology. Office of Scientific and Technical Information (OSTI), março de 2010. http://dx.doi.org/10.2172/973392.

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Tamulis, Arvydas, e Jelena Tamuliene. Ab Initio Quantum Chemical Design of Single Supermolecule Photoactive Machines and Molecular Logical Devices. Fort Belvoir, VA: Defense Technical Information Center, janeiro de 2001. http://dx.doi.org/10.21236/ada388289.

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Schiefelbein, J. Molecular genetics of myosin motors in Arabidopsis. Final report, July 1, 1992--June 30, 1996. Office of Scientific and Technical Information (OSTI), fevereiro de 1997. http://dx.doi.org/10.2172/486111.

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Molecular genetics of myosin motors in Arabidopsis. Progress report, [July 1, 1992--February 28, 1994]. Office of Scientific and Technical Information (OSTI), junho de 1994. http://dx.doi.org/10.2172/10159300.

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