Bibliografie tematiche / Substrats structurés

Letteratura scientifica selezionata sul tema "Substrats structurés"

Autore: Grafiati

Pubblicato: 8 giugno 2024

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Articoli di riviste sul tema "Substrats structurés":

Lohman, Jeremy R., Ming Ma, Jerzy Osipiuk, Boguslaw Nocek, Youngchang Kim, Changsoo Chang, Marianne Cuff et al. "Structural and evolutionary relationships of “AT-less” type I polyketide synthase ketosynthases". Proceedings of the National Academy of Sciences 112, n. 41 (29 settembre 2015): 12693–98. http://dx.doi.org/10.1073/pnas.1515460112.

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Acyltransferase (AT)-less type I polyketide synthases (PKSs) break the type I PKS paradigm. They lack the integrated AT domains within their modules and instead use a discrete AT that acts in trans, whereas a type I PKS module minimally contains AT, acyl carrier protein (ACP), and ketosynthase (KS) domains. Structures of canonical type I PKS KS-AT didomains reveal structured linkers that connect the two domains. AT-less type I PKS KSs have remnants of these linkers, which have been hypothesized to be AT docking domains. Natural products produced by AT-less type I PKSs are very complex because of an increased representation of unique modifying domains. AT-less type I PKS KSs possess substrate specificity and fall into phylogenetic clades that correlate with their substrates, whereas canonical type I PKS KSs are monophyletic. We have solved crystal structures of seven AT-less type I PKS KS domains that represent various sequence clusters, revealing insight into the large structural and subtle amino acid residue differences that lead to unique active site topologies and substrate specificities. One set of structures represents a larger group of KS domains from both canonical and AT-less type I PKSs that accept amino acid-containing substrates. One structure has a partial AT-domain, revealing the structural consequences of a type I PKS KS evolving into an AT-less type I PKS KS. These structures highlight the structural diversity within the AT-less type I PKS KS family, and most important, provide a unique opportunity to study the molecular evolution of substrate specificity within the type I PKSs.

Середин, П. В., А. С. Леньшин, А. В. Федюкин, И. Н. Арсентьев, А. В. Жаботинский, Д. Н. Николаев, Harald Leiste e Monika Rinke. "Влияние разориентации подложки на состав, структурные и фотолюминесцентные свойства эпитаксиальных слоев, выращенных на GaAs(100)". Физика и техника полупроводников 52, n. 1 (2018): 118. http://dx.doi.org/10.21883/ftp.2018.01.45329.8565.

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AbstractThe influence of the degree of misorientation and treatment of a GaAs substrate on the structural and optical characteristics of homoepitaxial GaAs/GaAs(100) structures grown by metal–organic chemicalvapor deposition is studied. From the data obtained by a series of structural and spectroscopic techniques, it is shown that the degree of deviation of the substrate from the exact orientation towards the [110] direction by an angle of up to 4° brings about stepwise growth of the GaAs film in the initial stage and a further increase in the degree of misorienration towards the [110] direction to 10° results in an increase in the number of structural defects in the epitaxial film. At the same time, the samples of homoepitaxial structures grown by metal–organic chemical-vapor deposition on GaAs(100) substrates misoriented by 4° towards the [110] direction possess the highest photoluminescence efficiency; it is ~15% higher than the corresponding quantity for structures grown on precisely oriented GaAs(100) substrates. Preliminary polishing of the GaAs substrate (removal of an oxide layer) also yields the intensification of photoluminescence emission compared to emission in the case of an unpolished substrate of the same type. For samples grown on substrates misoriented by 4°, such an increase in the photoluminescence efficiency is ~30%.

Park, Jooyoung, Ann M. Guggisberg, Audrey R. Odom e Niraj H. Tolia. "Cap-domain closure enables diverse substrate recognition by the C2-type haloacid dehalogenase-like sugar phosphatasePlasmodium falciparumHAD1". Acta Crystallographica Section D Biological Crystallography 71, n. 9 (25 agosto 2015): 1824–34. http://dx.doi.org/10.1107/s1399004715012067.

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Haloacid dehalogenases (HADs) are a large enzyme superfamily of more than 500 000 members with roles in numerous metabolic pathways.Plasmodium falciparumHAD1 (PfHAD1) is a sugar phosphatase that regulates the methylerythritol phosphate (MEP) pathway for isoprenoid synthesis in malaria parasites. However, the structural determinants for diverse substrate recognition by HADs are unknown. Here, crystal structures were determined of PfHAD1 in complex with three sugar phosphates selected from a panel of diverse substrates that it utilizes. Cap-open and cap-closed conformations are observed, with cap closure facilitating substrate binding and ordering. These structural changes define the role of cap movement within the major subcategory of C2 HAD enzymes. The structures of an HAD bound to multiple substrates identifies binding and specificity-determining residues that define the structural basis for substrate recognition and catalysis within the HAD superfamily. While the substrate-binding region of the cap domain is flexible in the open conformations, this region becomes ordered and makes direct interactions with the substrate in the closed conformations. These studies further inform the structural and biochemical basis for catalysis within a large superfamily of HAD enzymes with diverse functions.

Sangian, Hanny F., e Arief Widjaja. "Effect of pretreatment method on structural changes of coconut coir dust". BioResources 12, n. 4 (13 settembre 2017): 8030–46. http://dx.doi.org/10.15376/biores.12.4.8030-8046.

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The pretreatment of a high lignin substrate, coconut coir dust, was studied by chemical techniques (NaOH solution, ionic liquid, and NaOH followed by ionic liquid) and by a physical method (subcritical water, SCW). Following substrate pretreatment and a washing step, structural analyses were performed by scanning electron microscopy, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy. It was found that all substrates pretreated by chemical methods had more amorphous structures than the untreated substrate. The XRD patterns of the chemically treated substrates shifted toward higher angles by 0.50° to 1.00°. However, the XRD peak symmetry of the SCW-treated substrate did not shift, but its crystallinity index decreased. The results revealed that lignocellulose treated with NaOH followed by ionic liquid at 120 °C for 30 min showed the greatest extent of structural transformation.

Hao, Yue, Elizabeth Pierce, Daniel Roe, Maho Morita, John A. McIntosh, Vinayak Agarwal, Thomas E. Cheatham, Eric W. Schmidt e Satish K. Nair. "Molecular basis for the broad substrate selectivity of a peptide prenyltransferase". Proceedings of the National Academy of Sciences 113, n. 49 (21 novembre 2016): 14037–42. http://dx.doi.org/10.1073/pnas.1609869113.

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The cyanobactin prenyltransferases catalyze a series of known or unprecedented reactions on millions of different substrates, with no easily observable recognition motif and exquisite regioselectivity. Here we define the basis of broad substrate tolerance for the otherwise uncharacterized TruF family. We determined the structures of the Tyr-prenylating enzyme PagF, in complex with an isoprenoid donor analog and a panel of linear and macrocyclic peptide substrates. Unexpectedly, the structures reveal a truncated barrel fold, wherein binding of large peptide substrates is necessary to complete a solvent-exposed hydrophobic pocket to form the catalytically competent active site. Kinetic, mutational, chemical, and computational analyses revealed the structural basis of selectivity, showing a small motif within peptide substrates that is sufficient for recognition by the enzyme. Attaching this 2-residue motif to two random peptides results in their isoprenylation by PagF, demonstrating utility as a general biocatalytic platform for modifications on any peptide substrate.

Калыгина, В. М., В. И. Николаев, А. В. Алмаев, А. В. Цымбалов, В. В. Копьев, Ю. С. Петрова, И. А. Печников e П. Н. Бутенко. "Влияние ультрафиолетового излучения и электрического поля на проводимость структур на основе alpha- и ε-Ga-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=-". Физика и техника полупроводников 54, n. 10 (2020): 1035. http://dx.doi.org/10.21883/ftp.2020.10.49940.9449.

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The influence of ultraviolet radiation and a strong electric field on the current-voltage characteristic of resistive structures based on polymorphic films of gallium oxide is studied. Both types of Ga2O3 films were obtained by the method of chloride vapor-phase epitaxy on smooth and structured sapphire substrates with orientation (0001). In the same process α-Ga2O3 films were deposited on smooth substrates, and gallium oxide films, with regular structures perpendicular to the substrate, containing alternating regions of the α- and ε-phases were deposited on patterned substrate. It’s was observed, that radiation with λ = 254 nm and strong electric transfer structures from a state with low resistance to a state with high resistance. The response time to UV radiation is 5 seconds, and the recovery time less than 1 s.

Tandrup, Tobias, Kristian E. H. Frandsen, Katja S. Johansen, Jean-Guy Berrin e Leila Lo Leggio. "Recent insights into lytic polysaccharide monooxygenases (LPMOs)". Biochemical Society Transactions 46, n. 6 (31 ottobre 2018): 1431–47. http://dx.doi.org/10.1042/bst20170549.

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Lytic polysaccharide monooxygenases (LPMOs) are copper enzymes discovered within the last 10 years. By degrading recalcitrant substrates oxidatively, these enzymes are major contributors to the recycling of carbon in nature and are being used in the biorefinery industry. Recently, two new families of LPMOs have been defined and structurally characterized, AA14 and AA15, sharing many of previously found structural features. However, unlike most LPMOs to date, AA14 degrades xylan in the context of complex substrates, while AA15 is particularly interesting because they expand the presence of LPMOs from the predominantly microbial to the animal kingdom. The first two neutron crystallography structures have been determined, which, together with high-resolution room temperature X-ray structures, have putatively identified oxygen species at or near the active site of LPMOs. Many recent computational and experimental studies have also investigated the mechanism of action and substrate-binding mode of LPMOs. Perhaps, the most significant recent advance is the increasing structural and biochemical evidence, suggesting that LPMOs follow different mechanistic pathways with different substrates, co-substrates and reductants, by behaving as monooxygenases or peroxygenases with molecular oxygen or hydrogen peroxide as a co-substrate, respectively.

Kusakizako, Tsukasa, Yoshiki Tanaka, Andrés Maturana, Christopher Hipolito, Teruo Kuroda, Ryuichiro Ishitani, Hiroaki Suga e Osamu Nureki. "X-ray crystallographic analysis of a MATE multidrug transporter from V. cholerae". Acta Crystallographica Section A Foundations and Advances 70, a1 (5 agosto 2014): C709. http://dx.doi.org/10.1107/s2053273314092900.

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MATE (Multidrug And Toxic compound Extrusion) family transporters are highly conserved from Bacteria to Eukarya including human, and export a broad range of xenobiotics using either a proton or a sodium ion gradient across the membrane. Especially in bacterial pathogens, MATE transporters contribute to their multiple drug resistance (MDR). To understand how MATE transporters export various substrates such as drugs and thus how pathogens acquire MDR, structural analyses are essential. The crystal structures of several MATE transporters from pathogens have been reported. However, because of the limited resolution and the lack of drug-MATE transporters complex structures, the recognition mechanism of various substrates and the coupling mechanism of the cation influx and the drug efflux have been poorly understood. Although the high-resolution structures of MATE transporters from non-pathogenic archaeal P. furiosus (PfMATE) have been reported, PfMATE shares low sequence identity with MATE transporters from pathogens such as V. cholerae. Therefore, further findings of the structural mechanism of MDR caused by MATE transporters from pathogens have been needed. To understand the substrate recognition and transport mechanism of MATE transporters from pathogens, we determined the crystal structures of one of MATE transporters from V. cholerae (VcMATE) at 2.5-2.7 Å resolutions using in meso crystallization method. The high-resolution structures of VcMATE show two distinct conformations, as observed in the structures of PfMATE, and reveal the large movement of transmembrane helix 1 and the putative substrate-binding site. The structures suggest that the bending of transmembrane helix 1 and the sequential collapse of the putative substrate-binding site induce the release of the bound substrate. This conformational change during the substrate transport may be a common mechanism among MATE transporters from pathogens to non-pathogens.

Lamovec, Jelena, Vesna Jovic, Radoslav Aleksic e Vesna Radojevic. "Micromechanical and structural properties of nickel coatings electrodeposited on two different substrates". Journal of the Serbian Chemical Society 74, n. 7 (2009): 817–31. http://dx.doi.org/10.2298/jsc0907817l.

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Fine-structured nickel coatings were electrodeposited from a sulfamate-based electrolyte onto different substrates: polycrystalline cold-rolled copper and single crystal silicon with (111) orientation. The influence of the substrate layers and chosen plating conditions on the mechanical and structural properties of these composite structures were investigated by Vickers microhardness testing for different loads. Above a certain critical penetration depth, the measured hardness value was not the hardness of the electrodeposited film, but the so-called 'composite hardness', because the substrate also participated in the plastic deformations during the indentation process. Two composite hardness models (Chicot-Lesage and Korsunsky), constructed on different principles, were chosen and applied to the experimental data in order to distinguish film and substrate hardness. The microhardness values of the electrodeposited nickel layers were mainly influenced by the current density. Increasing the current density led to a decrease in grain size, which resulted in higher values of the microhardness.

Gai, Pratibha L., Rahul Mitra e Julia R. Weertman. "Structural variations in nanocrystalline nickel films". Pure and Applied Chemistry 74, n. 9 (1 gennaio 2002): 1519–26. http://dx.doi.org/10.1351/pac200274091519.

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Nanocrystalline nickel films of technological importance have been grown on various liquid nitrogen-cooled substrates by magnetron sputtering with and without a substrate bias. The atomic structural and chemical studies have unveiled variations in inter- and intragranular structures under the different process conditions. The origin and the development of the crystallization process with and without the substrate bias voltage have been inferred from the results.

Più fonti

Tesi sul tema "Substrats structurés":

Bugnicourt, Ghislain. "Adhésion, croissance et polarisation de neurones sur substrats micro-et nano-structurés". Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00665074.

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Cette thèse s'intéresse au développement neuronal in vitro dans le but ultime d'enregistrer l'activité de réseaux de neurones à géométrie et connectivité contrôlées. Le développement neuronal est régi par un ensemble de régulations, intrinsèques mais également sous contrôle de facteurs extérieurs, qui permettent à la cellule d'adhérer à un substrat, de croître, et de se polariser. Une partie de ce travail de thèse explore deux types de contraintes physiques de l'environnement que sont la géométrie d'adhésion et la rugosité de surface. La première révèle l'implication des forces dans les stades précoces de développement neuronal régis par un phénomène de compétition neuritique, et permet in fine de contrôler la direction d'émission de l'axone, notamment par une inhibition de sa différenciation sur lignes ondulées. La seconde montre que la distribution des points d'adhésion peut accélérer la croissance jusqu'à favoriser la polarisation axonale. L'autre partie de ce travail s'attache à résoudre le problème technologique majeur qu'est le remplissage des sites d'adhésion par le biais d'une attraction magnétique, et démontre la possibilité de faire croître des réseaux neuronaux modèles sur nanotransistors.

Ni, Xiaofang. "Culture et différenciation cellulaire sur des substrats structurés et dans des dispositifs microfluidiques". Paris 6, 2009. http://www.theses.fr/2009PA066666.

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Les technologies de nanofabrication et de microfluidique sont aujourd'hui largement utilisées pour les études de la biologie cellulaire. Il est particulièrement intéressant d'utiliser ces nouvelles technologies afin de contrôler plus précisément la culture et la différenciation des cellules souches. Tout d'abord, deux nouvelles méthodes de lithographie, i. E. , la micro-aspiration par dégazage et la nano-impression UV molle sont présentées, en tenant compte des exigences pour la culture cellulaire. Des motifs de protéines ont été également obtenus dans des dispositifs microfluidiques, permettant de contrôler le positionnement cellulaire dans un micro-environnement particulier. Ensuite, de nouveaux dispositifs microfluidiques ont été conçus et utilisés pour évaluer la performance de la culture et la différenciation des cellules souches embryonnaires. Puis, en adaptant les protocoles existants et utilisant des chambres microfluidique à plusieurs compartiments, nous avons démontré la différenciation de cellules souches mésenchymateuses vers des cellules adipogéniques et cellules neurales. Enfin, la formation des réseaux cellulaires a été étudiée en utilisant les deux types de cellules souches et de facteurs de différentiation neuronale. En plus, nous avons initié des essais sur la fabrication des réseaux de micro-électrodes et le test de culture cellulaire sur ces réseaux afin de démontrer la transduction du signal de neurones sur puce.

Assaud, Loic. "Fonctionnalisation de substrats nano-structurés pour la conversion et le stockage de l'énergie". Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4049.

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Afin de répondre au besoin de la société actuelle qui utilise toujours plus de moyens de transport et de dispositifs portables, les modes de production, de conversion et de stockage de l'énergie, sont en train de connaître de véritables mutations. Afin de créer des systèmes capables de générer une énergie maîtrisée et renouvelable, les nanosciences et nanotechnologies sont des domaines de premier plan. Le travail présenté dans ce manuscrit décrit la fabrication de structures, de taille nanométrique, organisées à grande échelle. La fonctionnalisation se fait par synthèse de films ou de particules par ALD. Des systèmes MIM sont synthétisés sur des structures ordonnées d'alumine poreuse. Les matériaux déposés en couches minces sont TiN, Al2O3 et HfO2. L'objectif est de fabriquer des nano-condensateurs à hautes performances pouvant être utilisés pour des applications de stockage de données, de mémoire ou pour le stockage d'énergie dans des petits dispositifs comme la technologie RFID.Dans une deuxième partie, des catalyseurs métalliques Pd/Ni sont déposés sur des membranes d'alumine pour l'électro-oxydation de l'acide formique. De la même manière, des nano-tubes de TiO2 fabriqués par oxydation anodique sont fonctionnalisés par des nano-particules de Pd pour l'électrooxydation de l'éthanol. Ces deux études systèmes peuvent conduire à leur utilisation comme catalyseurs au niveau de l'anode des piles à combustible liquide à combustion directe. Enfin, la dernière partie de ce travail consiste au dépôt par voie électrochimique de Cu2O, sur des nano-tubes de TiO2 qui servent de support. La jonction p/n ainsi fabriquée pourra servir pour la photo-conversion de l'énergie solaire
In order to meet the growing needs in today's society that requests more transportation and portable devices, energy production, conversion and storage systems are now experiencing real changes. To fabricate systems able to generate a controlled and renewable energy, nanoscience and nanotechnology are leading research fields. The work presented in this manuscript describes the fabrication of nanosized, large-scale organized structures. These nanostructures have been functionalized through film and particle synthesis using a chemical vapor deposition method: the Atomic Layer Deposition (ALD).Thus, metal/insulator/metal (MIM) systems are fabricated on highly-ordered high-aspect ratio porous alumina. The materials that have been deposited are TiN, Al2O3 and HfO2. The aim is to produce high performance nanocapacitors that can be used for data storage (DRAM) application or for energy storage in small devices such as RFID.In a second part, metallic catalysts such as Pd/Ni have been deposited on alumina membranes for formic acid electro-oxidation. Similarly, TiO2 nanotubes have been fabricated by anodic oxidation and they have been functionalized with Pd nanoparticles for ethanol electro-oxidation. Both studied systems can be used as anode catalysts in direct liquid fuel cells.Finally, the last part of this work has consisted in the study of Cu2O, as a p-type semiconductor, that has been electrochemically deposited onto TiO2 nanotubes (n-type semiconductor). The resulting p/n junction can be interesting for solar energy photoconversion

El, Khoury Maroun Michel. "Croissance de GaN semipolaire par épitaxie en phase vapeur aux organométalliques sur substrats de Si structurés". Thesis, Nice, 2016. http://www.theses.fr/2016NICE4001.

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Jusqu'à présent, les dispositifs optoélectroniques commerciaux sont épitaxiés selon la direction c, qui souffre de deux limitations intrinsèques. D'une part, les fortes discontinuités de polarisation le long de l'hétéro-interfaces des nitrures qui sont responsables de l'effet Stark de confinement quantique. Ceci mène dans le cas des dispositifs optiques GaN à une séparation de la fonction d'onde électron-trou dans les puits quantiques. D'une autre part, l'incorporation d'indium sur les plans polaires (0001) se trouve être relativement limité par comparaison avec les autres orientations cristallographiques. Ces effets néfastes peuvent être partiellement dépasser en performant la croissance du GaN sur des plans cristallographiques autre que le plan (0001). Ces plans semi polaires conduit éventuellement à l'amélioration des performances du dispositif. En fait, comme la seule solution disponible pour l'instant pour la croissance du GaN semipolaire est l'homoépitaxie, les dispositifs à base de GaN semipolaire de haute qualité a ses inconvénients qui est la petite taille et le prix élevé des substrats. Cela justifie la croissance du GaN semi-polaire sur d'autre type de substrats spécialement le silicium. Dans cette étude, la croissance de couches de GaN semi-polaire (10-11) et (20-21) par MOVPE sur des substrats de silicium structurés sera évaluée. La stratégie générale de fabrication consiste a structuré l'orientation adaptée du substrat silicium de façon à révéler les facettes Si(111)
To-date, commercial III-nitride optoelectronic devices are grown along the c-direction, which suffers two intrinsic limitations. The first is the strong polarization discontinuities across nitride hetero-interfaces that are responsible for the quantum confined Stark effect, leading in the case of GaN-based optical devices to electron-hole wave function separation within the quantum wells, and thus, a decrease in the oscillator strength. The associated longer exciton lifetime together with the occurrence of non-radiative defects, result in reducing the device's efficiency. The second is the indium incorporation on the polar plane, which is relatively limited when compared with its incorporation on other crystallographic orientations. These deleterious effects can be partially overcome by performing the growth of GaN on planes other than (0001), such as semipolar ones leading to the eventual improvement of devices' performances. Growth of device-quality semipolar GaN, however, comes at a price, and the only currently available option is homoepitaxy, which is limited in size and is highly priced. At this point, the growth on foreign substrates becomes appealing, especially on silicon. In this thesis, the MOVPE growth of (10-11) and (20-21) semipolar GaN on patterned silicon substrates has been performed. The general fabrication strategy, which consists of patterning the appropriate silicon wafer orientation in order to reveal the Si (111) facets, will be first described. Subsequently, the selective growth of GaN along the c-direction will be carried out, where the c-oriented crystals will be brought to coalescence until a semipolar layer is achieved

Richard, Marie-Ingrid. "Étude in situ et ex situ par rayonnement synchrotron de la croissance d’îlots de GE sur substrats de Si (001) nominaux et pré-structurés". Grenoble 1, 2007. http://www.theses.fr/2007GRE10318.

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Les travaux présentés dans ce manuscrit sont consacrés à l'étude structurale (taille, déformation, défauts, composition) d'Îlots de Ge sur substrats de Si(OOI) nominaux et pré-structurés durant ou après croissance par épitaxie par jet moléculaire, en utilisant la diffraction (anomale) des rayons X en incidence rasante à l'ESRF. Les échantillons ont été caractérisés soit ex situ apre��s croissance sur la ligne de lumière IDOI, soit in situ durant leur croissance par EJM grâce au dispositif dédié sur la ligne BM32. Les effets dynamiques associés à l'utilisation de l'incidence rasante ont été étudiés sur la base de simulations des champs de déformations dans les nanostructures de Ge. Une nouvelle technique de rayons X a été développée pour détecter leur présence et étudier la structure de leur cœur en se concentrant sur l'intensité diffusée par les défauts autour de réflexions interdites. La forme, la taille, le mode de croissance, la composition et la présence éventuelle de défauts et/ou d'ordre atomique à l'intérieur des nanostructures ont été caractérisés en fonction du dépôt, de sa température, de la vitesse de croissance et du recuit, pour comprendre les dynamiques de croissance. L'évolution des déformations, la transition élastique-plastique, l'interdiffusion et leur relation avec les différentes morphologies des îlots ont été étudiés grâce à l'utilisation de techniques in situ de rayons X. Enfin, les croissances sur surfaces Si(OOI) nominales et pré-structurées ont été comparées, montrant qu'en modulant la surface, il est possible de changer l'état de relaxation et l'énergie élastique totale des îlots sans modifier leur composition moyenne en Ge
The work presented in this manuscript focuses on the structural (size, strain, defects, composition) investigation of Ge nano-islands grown on both nominal and pre-pattemed Si(OOI) substrates by Molecular Bearn, using grazing incidence (anomalous) X-ray diffraction and scattering at ESRF. The samples were either prepared in independent MBE chambers and then characterized ex situ on the IDOI ESRF beamline, or they were characterized in situ during their MBE growth, using the BM32 ESRF beamline setup. The dynamical scattering effects occurring in grazing incidence have been studied on the basis offinite element simulations of the strain fields in nano-islands. A novel X-ray method has been developed to detect the presence of defects and to study the structure oftheir core by concentrating on measurements along rods of scattering by defects passing through bulk forbidden reflections. To obtain new insight into the dynamics of growth phenomena, the shape, size, growth mode, composition and possible defects and/or atomic ordering inside aIl islands were characterized, as a function of deposition, deposition temperature, flux and possible annealing. The evolution ofstrain, the transition from elastic to plastic relaxation, the intermixing and the correlation ofthese internaI parameters with the different morphologies of the island have been addressed using in situ scattering methods. At last, the growth on nominal and patterned Si(OO 1) surfaces were compared, showing that by tuning the surface curvature, it is possible to change the relaxation state and the overaIl elastic energy of islands without modifying their mean Ge composition

Selmi, Mayada. "Textures à la surface libre de cristaux liquides smectiques : étude en géométrie films librement suspendus et sur substrats structurés". Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0098/document.

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Ces travaux concernent l’étude expérimentale des textures se développant dans les ménisques de films smectiques de cristaux liquides thermotropes. Ces fluides complexes nous servent de système modèle pour l’étude des couplages élasto-capillaires qui se manifestent dans certaines conditions par des déformations périodiques de l’interface cristal liquide-air. Dans un premier temps, à partir de l’étude détaillée de la topographie de l’interface par une méthode interférométrique, nous caractérisons les différents types de structures, puis, identifions les principaux paramètres impliqués dans le processus d'apparition des défauts dans le ménisque de films libres suspendus. Ces résultats nous servent de base pour discuter des mécanismes physiques qui génèrent les différents types de défauts observés. Nous regardons en particulier, comment la diminution d’épaisseur de couche associée à une transition de phase va induire une instabilité mécanique responsable de l’apparition des ondulations de l’interface. Dans un deuxième temps, afin d’aller plus loin dans la compréhension des mécanismes, nous avons utilisé des films minces de cristaux liquides déposés sur des substrats solides microstructurés par des plots fabriqués par des techniques photolitographiques. Une telle géométrie permet de générer un ménisque autour de chaque plot et surtout de faire varier un plus grand nombre de paramètres comme par exemple l’ancrage sur le substrat via un traitement chimique de surface. L’ensemble de nos résultats apportent un éclairage nouveau sur la caractérisation et la compréhension des déformations spécifiques aux ménisques de fluides complexes
The present work is an experimental study of the textures that appear in the meniscus of free standing smectic films with thermotropic liquid crystals. These complex fluids serve as model systems to investigate elasto-capillary phenomena which, under certain conditions, manifest themselves through periodic deformations of the liquid crystalair interface. In the first part of the thesis, we focus our attention on meniscus structures whose interfacial topographies are thoroughly characterized thanks to an in-house optical interferometry technique. Our study allows us to identify the main parameters involved in the development of meniscus structures and to discuss the physical mechanisms that are likely to be responsible for their formation. In particular, we show how a phase transition-induced layer shrinkage triggers a mechanical instability leading to interfacial undulations of the smectic free surface. In the second part of the manuscript, we address the case of thin liquid crystal films deposited on solid patterned solid substrates. The latter consist of regular arrays of microposts fabricated through photolithographic techniques. Such a geometry allows a meniscus to be formed around each micropost and makes it possible to examine the influence of other parameters such as the anchoring conditions on the solid substrate. The results gathered so far are able to shed some light on the characterization and the understanding of the specific deformations and textures that appear in the menisci of complex fluids

Richard, Céline J. E. "Phénomènes de mouillage aux petites échelles sur des substrats non structurés et structurés : films minces de cristaux liquides et propriétés de mouillage des liquides ioniques aux petites échelles". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2011. http://tel.archives-ouvertes.fr/tel-00662524.

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A une époque où la miniaturisation est l'un des principaux défis de la science, la physique du mouillage aux petites échelles est loin d'être complètement comprise. Le rôle structurant des interfaces, les hétérogénéités du substrat ou l'occurrence d'effets dits de "ligne" commencent à se faire sentir. Le but de la présente thèse, expérimentale, est d'apporter de nouveaux indices permettant le développement des analyses théoriques. Deux systèmes à petite échelle et complexes ont été étudiés : les films minces de cristaux liquides sur substrat liquide et les précurseurs de liquides ioniques sur substrats solides. La description des propriétés de mouillage des cristaux liquides nématiques nécessite deux ingrédients s'ajoutant à ceux des liquides usuels : l'élasticité, qui est source d'interactions à longue portée et l'ancrage qui décrit le rôle spécifique joué par les conditions aux limites. Sur un substrat liquide, les films minces nématiques avec des conditions d'ancrage antagonistes montrent des structures complexes ainsi qu'une coexistence d'épaisseurs. Différents systèmes ont été étudiés au microscope optique dans la gamme de température nématique et aux alentours de la transition nématique / isotrope. Les résultats ont été comparés aux modèles disponibles qui sont basés sur une théorie continue de l'élasticité nématique. Les liquides ioniques sont des sels surfondus à température ambiante. Ils sont devenus omniprésents dans l'industrie, ce qui explique que la compréhension de leur mouillage soit un sujet brûlant. De faibles quantités de liquides ioniques ont été déposées sur différents substrats, lisses ou rugueux. Le paysage que l'on obtient, gouttelettes et films minces, a été imagé par AFM (Atomic Force Microscopy). Les résultats ont été comparés aux modèles disponibles pour les films minces et les gouttes nanoscopiques.

Fadel, Christy. "Influence of the Al content on the structure, optoelectronic properties and electronic structure of AZO transparent electrodes deposited by HiPIMS for solar energy conversion". Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0080.

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Dans cette thèse, l'influence de la concentration en dopant Al (Aluminium) sur les propriétés de films d'oxyde de zinc (ZnO) dopés par Al (AZO - Al-doped zinc oxide) synthétisés par pulvérisation magnétron impulsionnelle à haute puissance réactive (HiPIMS) est étudiée. Pour cela, des cibles de pulvérisation d'alliages Zn/Al à 1, 2, 5, 10 ou 15 at.% Al sont utilisées. Il est observé que la teneur en Al a une forte influence sur le processus de pulvérisation réactive, car il est plus facile de pulvériser et de déposer à des vitesses de dépôts élevées à partir de cibles contenant des teneurs en Al plus faibles. Cela s'explique par la forte réactivité de l'Al vis-à-vis de l'oxygène qui facilite la formation d'un oxyde d'aluminium en surface des cibles, et rend plus difficile la pulvérisation lors du bombardement par les ions de la phase plasma. Des films ont été synthétisés dans la gamme 0,56-14,71 at.% Al, où la structure et la microstructure du film évoluent de films colonnaires nanocristallins vers des films nanocristallins ultrafins lors de l'augmentation de la teneur en Al. La structure hexagonale wurtzite de ZnO est conservée pour toutes les conditions. Les mesures électriques réalisées sur les films élaborés ont révélé qu'un dopage efficace peut être atteint jusqu'à 3 at.% Al en utilisant la pulvérisation HiPIMS réactive. Plus important encore, on constate que les mesures de structure électronique montrent des indices d'activation et de ségrégation de dopants qui peuvent servir à chercher l'origine de la dégradation des propriétés électriques et à optimiser les propriétés électriques des films AZO. Enfin, des empilements de couches minces visant à fabriquer des cellules photovoltaïques ont été réalisés selon la séquence verre plat ou structuré/AZO/ZnO/Cu₂O/Au. La structuration a été réalisée par interférence laser directe à pulses ultracourts, et la morphologie et la microstructure obtenues sont présentées ainsi que des stratégies possibles pour permettre le développement de cellules efficaces
In this work, the influence of Al (Aluminum) dopant concentration on the properties of Al-doped ZnO (AZO) films synthesized by reactive High Power Impulse Magnetron Sputtering (HiPIMS), and deposited from Zn/Al targets with 1, 2, 5, 10 or 15 at.% Al is studied. It is observed that the Al content has a strong influence on the reactive sputtering process, as it is easier to sputter-deposit at high rates from targets containing lower Al contents. This is explained by the high reactivity of Al towards oxygen, which easily poisons the target surface with Al oxide more difficult to etch upon bombardment by ions from the plasma phase. Films have been synthesized in the 0.56-14.71 at.% Al range, where the film structure and microstructure evolves from nanocrystalline columnar films towards ultrafine nanocrystalline films of wurtzite ZnO structure upon increasing the Al content. The electrical properties revealed that effective doping may be achieved up to 3 at.% Al by using HiPIMS. And most importantly, it is found that electronic structure measurements contain signatures of dopant activation and segregation that may serve to investigate on the origin of electrical properties degradation and to optimize the electrical properties of AZO films. Finally, flat or structured glass/AZO/ZnO/Cu₂O/Au thin film stacks were made. The patterning was done by ultrashort pulsed direct laser interference patterning, and the morphology and microstructure are presented together with possible strategies to improve the preliminary electrical results

Garcia, Pardo Javier. "Structural and functional characterization of regulatory metallocarboxypeptidases: Studies on human carboxypeptidases D and Z, and the transthyretin-like domain". Doctoral thesis, Universitat Autònoma de Barcelona, 2015. http://hdl.handle.net/10803/319703.

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Las metalocarboxipeptidasas (MCPs) son enzimas zinc-dependientes que hidrolizan amino ácidos del extremo C terminal en proteínas y péptidos. La primera MCP en ser identificada fue la carboxipeptidasa A1 (CPA1), una enzima pancreática que hidroliza residuos C terminales hidrofóbicos. En las décadas siguientes después del descubrimiento de la CPA1, docenas de MCPs adicionales han sido descritas en diferentes tejidos y fluidos extrapancreaticos, comprendiendo un amplio rango de funciones fisiológicas que van desde la digestión de los alimentos hasta la producción de neuropéptidos y hormonas peptídicas o el procesamiento selectivo de la tubulina. La presente tesis tiene como objeto profundizar en el conocimiento de la estructura y función biológica de dos MCPs reguladoras. Para este propósito, se aplicaron un amplio espectro de aproximaciones bioquímicas con el fin de elucidar la actividad biológica de las carboxipeptidasas D y Z humanas. Además, se decidió estudiar por primera vez la estructura y funciones de los dominios tipo transtiretina (TTL) que se encuentran en todos los miembros de esta subfamilia de proteasas, escogiéndose como ejemplo el primer dominio TTL perteneciente al primer dominio catalítico de la carboxipeptidasa D humana (denominada en este trabajo como h-TTL). En el primer capítulo se describe la formación de estructuras amiloides bajo condiciones fisiológicas por el dominio h-TTL, y se descubre que el motivo de plegamiento transtiretina monomérico tiene una propensión inherente a agregar, dada la presencia de elementos estructurales amiloidogénicos preformados. El mecanismo de agregación que se describe en este trabajo para una proteína nativa monomérica tipo transtiretina, también se ha encontrado en diversas proteínas globulares, inicialmente solubles y asociadas con enfermedades conformacionales que se generan por la deposición de agregados, pudiendo ser un hecho genérico para motivos de plegamiento que muestren elementos amiloidogenicos preformados en sus estructuras, esencialmente hojas β. El segundo capítulo muestra la estructura cristalográfica resuelta a súper alta resolución de la h-TTL descrita en el primer capítulo. La información derivada del presente estudio podría facilitar el conocimiento del papel biológico de los dominios TTL encontrados en todos los miembros de la subfamilia M14B, pudiendo ser utilizada como una herramienta interesante para analizar en detalle las propiedades estructurales y los mecanismos de plegamiento de estos dominios. El tercer capítulo comprende la caracterización de la especificidad de sustrato de la carboxipeptidasa D humana, utilizando una combinación de diferentes aproximaciones peptidómicas cuantitativas. Esta enzima única con múltiples centros catalíticos, podría estar implicada en el procesamiento de neuropéptidos y factores de crecimiento. Por lo tanto, el estudio de su mecanismo de acción es de especial relevancia para el campo de la biomedicina. En el cuarto capítulo se describe el desarrollo de un método simple y barato para mejorar la producción proteica de carboxipeptidasas que presentan afinidad por heparina usando células de mamífero, cogiendo como ejemplo el caso de la carboxipeptidasa Z. La proteína purificada mediante este sistema es enzimáticamente activa y puede ser utilizada para estudios estructurales y funcionales de alto rendimiento. En el último capítulo se utilizan diferentes aproximaciones peptidómicas cuantitativas para caracterizar la especificidad de sustrato de la carboxipeptidasa Z humana. Además, en este trabajo se presenta el modelado de su dominio catalítico, así como el de su dominio tipo frizzled, con el fin de analizar su papel en la vía señalización de Wnt.
Metallocarboxypeptidases (MCPs) are zinc-dependent enzymes that cleave single amino acids from the C termini of proteins and peptides. The first MCP to be identified was carboxypeptidase A1 (CPA1), a pancreatic enzyme that removes C-terminal hydrophobic residues. In the ensuing decades since the discovery of CPA1, dozens of additional MCPs have been found in different extra-pancreatic tissues and fluids, comprising a wide range of physiological roles ranging from digestion of food to the production of neuropeptides and peptide hormones and the selective processing of tubulin. The present thesis has the aim to gain insights into the knowledge of the structure and biological functions of two regulatory MCPs. For this purpose, we applied a wide range of biochemical approaches to elucidate biological activities of human carboxypeptidases D and Z. Furthermore, we decided to study for the first time the structure and roles of the transthyretin-like (TTL) domains found in all members of this subfamily of proteases, taking as example the first TTL domain belonging to the first catalytic domain of human carboxypeptidase D (termed here as h-TTL). The first chapter describes the amyloid formation under physiological conditions by h-TTL and unravels that the monomeric transthyretin fold has an inherent propensity to aggregate due to the presence of preformed amyloidogenic structural elements. The aggregation mechanism described in this work for a natively monomeric transthyretin-like protein, is being found also in a number of initially soluble globular proteins associated with protein deposition diseases and might be in fact quite generic for folds displaying preformed amyloidogenic elements in their structures, essentially β-sheets. The second chapter presents the crystal structure solved at ultra-high resolution of the h-TTL described in the first chapter. The information derived in the present study might facilitate the understanding of the biological roles of the TTL domains found in M14B subfamily members and would be an interesting tool to analyze in detail the structural properties and the folding mechanisms of these domains. The third chapter comprises the characterization of the substrate specificity of human carboxypeptidase D by using a combination of quantitative peptidomic approaches. This unique enzyme with multiple catalytic sites might be implicated in the processing of neuropeptides and growth factors. Thereby, the study of its mechanism of action is of significant importance for biomedicine. The fourth chapter describes de development of a simple and inexpensive method to improve protein production of heparin-affinity carboxypeptidases using mammalian cells, taking as example the case of carboxypeptidase Z. The purified protein is enzymatically active and can be used for high-throughput functional and structural studies. The fifth chapter applies several quantitative peptidomic approaches to characterize the substrate specificity of the human carboxypeptidase Z. Furthermore, this work provides the modelling of its catalytic domain, as well as of their frizzled-like domain, in order to analyze their role in Wnt signaling.

Chaban, Nicolas. "Ingénierie des contraintes de films minces d'oxydes de LaNiO3 : les substrats piézoélectriques". Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00721808.

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Ce travail est né de l'idée d'associer l'ingénierie des matériaux sous forme de couches minces, domaine qui motive depuis de nombreuses années les chercheurs du LMGP, à des substrats piézoélectriques à fort coefficients de déformation. Les matériaux piézoélectriques peuvent convertir une énergie électrique en une énergie mécanique (de déformation) et vice-versa. Il est alors aisé d'imaginer qu'une couche mince synthétisée à la surface d'un substrat piézoélectrique profitera de la déformation de ce dernier quand il est soumit à un champ électrique. Le substrat mis en jeu est le PMN-PT, composé qui présente de forts coefficients de déformation. Dans cette étude le film synthétisé et mis en œuvre est le LaNiO3. Il cristallise dans une structure pérovskite ABO3. Cette structure présente l'avantage de permettre une grande variété de distorsions structurales et peut accueillir un grand nombre d'éléments chimiques.

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Libri sul tema "Substrats structurés":

Ecker, Gerhard, e Peter Chiba. Transporters as drug carriers: Structure, function, substrates. Weinheim: Wiley-VCH, 2009.

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Doniach, Sebastian, a cura di. Statistical Mechanics, Protein Structure, and Protein Substrate Interactions. Boston, MA: Springer US, 1994. http://dx.doi.org/10.1007/978-1-4899-1349-4.

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Ogbuji, L. U. J. T. Process-induced carbon and sub-layer in SiC/BN/SiC composites: Characterization and consequences. [Cleveland, Ohio]: National Aeronautics and Space Administration, Glenn Research Center, 2001.

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R, Wheeler Donald, McCue T. R e NASA Glenn Research Center, a cura di. Process-induced carbon and sub-layer in SiC/BN/SiC composites: Characterization and consequences. [Cleveland, Ohio]: National Aeronautics and Space Administration, Glenn Research Center, 2001.

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International, Workshop on Characterization of Semiconductor Substrates and Structures (1992 Smolenice Czechoslovakia). Characterization of semiconductor substrates and structures: Proceedings of the International Workshop on Characterization of Semiconductor Substrates and Structures, Smolenice, Czechoslavakia, 1-4 April, 1992. Amsterdam: North Holland, 1993.

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M, Schieber Michael, e Korytár D, a cura di. Characterization of semiconductor substrates and structures: Proceedings of the international workshop on characterization of semiconductor substrates and structures, Smolenice, Czechoslovakia, 1-4 April 1992. Amsterdam: North-Holland, 1993.

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Suzanne, Michaelis, a cura di. Roots of Creole structures: Weighing the contribution of substrates and superstrates. Philadelphia: John Benjamins, 2008.

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Eberl, Karl, Pierre M. Petroff e Piet Demeester, a cura di. Low Dimensional Structures Prepared by Epitaxial Growth or Regrowth on Patterned Substrates. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0341-1.

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Eberl, Karl. Low Dimensional Structures Prepared by Epitaxial Growth or Regrowth on Patterned Substrates. Dordrecht: Springer Netherlands, 1995.

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Karl, Eberl, Petroff Pierre M, Demeester Piet, North Atlantic Treaty Organization. Scientific Affairs Division. e NATO Advanced Research Workshop on Low Dimensional Structures Prepared by Epitaxial Growth or Regrowth on Patterned Substrates (1995 : Rottach-Egern, Germany), a cura di. Low dimensional structures prepared by epitaxial growth or regrowth on patterned substrates. Dordrecht: Kluwer Academic Publishers, 1995.

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Capitoli di libri sul tema "Substrats structurés":

Costa, Valentina, Renato Chemello, Davide Iaciofano, Sabrina Lo Brutto e Francesca Rossi. "Seagrass detritus as marine macroinvertebrates attractor". In Ninth International Symposium “Monitoring of Mediterranean Coastal Areas: Problems and Measurement Techniques”, 619–26. Florence: Firenze University Press, 2022. http://dx.doi.org/10.36253/979-12-215-0030-1.58.

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Seagrass detritus is used as food, physical habitat and shelter. Using natural and artificial detritus, we tested if: 1) the colonisation was related to substrate availability rather than food 2) the assemblages were similar according to meadow structural complexity. A total of 11,270 invertebrates were identified. Neither the habitat complexity, nor the substrate type shown any effects on the colonisation, with both substrates acting as a faunal magnet. The detritus can be colonised by a rich and diverse community, highlighting its important role in maintaining the seagrass meadow biodiversity

Mao, Youdong. "Structure, Dynamics and Function of the 26S Proteasome". In Subcellular Biochemistry, 1–151. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-58971-4_1.

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AbstractThe 26S proteasome is the most complex ATP-dependent protease machinery, of ~2.5 MDa mass, ubiquitously found in all eukaryotes. It selectively degrades ubiquitin-conjugated proteins and plays fundamentally indispensable roles in regulating almost all major aspects of cellular activities. To serve as the sole terminal “processor” for myriad ubiquitylation pathways, the proteasome evolved exceptional adaptability in dynamically organizing a large network of proteins, including ubiquitin receptors, shuttle factors, deubiquitinases, AAA-ATPase unfoldases, and ubiquitin ligases, to enable substrate selectivity and processing efficiency and to achieve regulation precision of a vast diversity of substrates. The inner working of the 26S proteasome is among the most sophisticated, enigmatic mechanisms of enzyme machinery in eukaryotic cells. Recent breakthroughs in three-dimensional atomic-level visualization of the 26S proteasome dynamics during polyubiquitylated substrate degradation elucidated an extensively detailed picture of its functional mechanisms, owing to progressive methodological advances associated with cryogenic electron microscopy (cryo-EM). Multiple sites of ubiquitin binding in the proteasome revealed a canonical mode of ubiquitin-dependent substrate engagement. The proteasome conformation in the act of substrate deubiquitylation provided insights into how the deubiquitylating activity of RPN11 is enhanced in the holoenzyme and is coupled to substrate translocation. Intriguingly, three principal modes of coordinated ATP hydrolysis in the heterohexameric AAA-ATPase motor were discovered to regulate intermediate functional steps of the proteasome, including ubiquitin-substrate engagement, deubiquitylation, initiation of substrate translocation and processive substrate degradation. The atomic dissection of the innermost working of the 26S proteasome opens up a new era in our understanding of the ubiquitin-proteasome system and has far-reaching implications in health and disease.

Varfolomeev, Sergey, Bella Grigorenko, Sofya Lushchekina, Patrick Masson, Galina Mahaeva e Alexander Nemuchin. "Human cholinesterases". In ORGANOPHOSPHORUS NEUROTOXINS, 69–126. ru: Publishing Center RIOR, 2020. http://dx.doi.org/10.29039/21_069-126.

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The work is devoted to modeling the elementary stages of the hydrolysis reaction in the active site of enzymes belonging to the class of cholinesterases — acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The study allowed to describe at the molecular level the effect of the polymorphic modification of BChE, causing serious physiolog ical consequences. Cholinesterase plays a crucial role in the human body. AChE is one of the key enzymes of the central nervous system, and BChE performs protective functions in the body. According to the results of calculations using the combined method of quantum and molecular mechanics (KM/MM), the mechanism of the hydrolysis of the native acetylcholine substrate in the AChE active center was detailed. For a series of ester substrates, a method for estimation of dependence of the enzyme reactivity on the structure of the substrate has been developed. The mechanism of hydrolysis of the muscle relaxant of succininylcholine BChE and the effect of the Asp70Gly polymorph on it were studied. Using various computer simulation methods, the stability of the enzyme-substrate complex of two enzyme variants with succinylcholine was studied.

Varfolomeev, Sergey, Bella Grigorenko, Sofya Lushchekina e Alexander Nemuchin. "Human cholinesterases". In Organophosphorous Neurotoxins, 63–120. ru: Publishing Center RIOR, 2020. http://dx.doi.org/10.29039/chapter_5e4132b5f22366.15634219.

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Delan-Forino, Clémentine, e David Tollervey. "Mapping Exosome–Substrate Interactions In Vivo by UV Cross-Linking". In Methods in Molecular Biology, 105–26. New York, NY: Springer New York, 2019. http://dx.doi.org/10.1007/978-1-4939-9822-7_6.

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AbstractThe RNA exosome complex functions in both the accurate processing and rapid degradation of many classes of RNA in eukaryotes and Archaea. Functional and structural analyses indicate that RNA can either be threaded through the central channel of the exosome or more directly access the active sites of the ribonucleases Rrp44 and Rrp6, but in most cases, it remains unclear how many substrates follow each pathway in vivo. Here we describe the method for using an UV cross-linking technique termed CRAC to generate stringent, transcriptome-wide mapping of exosome–substrate interaction sites in vivo and at base-pair resolution.

Prinz, G. A. "Magnetic Metal Films on Semiconductor Substrates". In Ultrathin Magnetic Structures II, 1–44. Berlin, Heidelberg: Springer Berlin Heidelberg, 1994. http://dx.doi.org/10.1007/3-540-27166-x_1.

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Samanta, Swagata, Pallab Banerji e Pranabendu Ganguly. "Design and Development of Some SU-8 Wire Waveguide Structures". In Photonic Waveguide Components on Silicon Substrate, 53–79. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-15-1311-4_4.

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Hitomi, Kiyotaka, e Hideki Tatsukawa. "Preferred Substrate Structure of Transglutaminases". In Transglutaminases, 63–82. Tokyo: Springer Japan, 2015. http://dx.doi.org/10.1007/978-4-431-55825-5_3.

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Szegletes, Tivadar, William D. Mallender e Terrone L. Rosenberry. "Substrate Binding to the Acetylcholinesterase Peripheral Site Promotes Substrate Hydrolysis but also Gives Rise to Substrate Inhibition". In Structure and Function of Cholinesterases and Related Proteins, 229. Boston, MA: Springer US, 1998. http://dx.doi.org/10.1007/978-1-4899-1540-5_59.

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Adler, L. "Spectroscopic Evaluation of Layered Substrates". In The Evaluation of Materials and Structures by Quantitative Ultrasonics, 133–47. Vienna: Springer Vienna, 1993. http://dx.doi.org/10.1007/978-3-7091-4315-5_9.

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Atti di convegni sul tema "Substrats structurés":

Jang, Woong Ki, Yong Min Park, Young Ho Seo e Byeong Hee Kim. "Fabrication of Hierarchical Micro-Nano Structures and Structural Coloring Effect of Polymer Substrate". In ASME 2014 International Manufacturing Science and Engineering Conference collocated with the JSME 2014 International Conference on Materials and Processing and the 42nd North American Manufacturing Research Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/msec2014-3934.

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Recently, structural coloring using hierarchical micro-nano structures as a technical field to implement a color without using a chemical colourants and dye is being developed as an attentional technology. The principle of structural coloring is that by the diffraction or multi-interference of light from a material containing a periodic or quasiperiodic structure on the length scale of the wavelength of visible light. For these reason, our research have verified the structural coloring effect on the polymer substrate by fabricate a hierarchical micro-nano structures. Firstly, we have fabricate a nano and hierarchical micro-nano structured mold for verify the structural size effect. Through the replication of structures on the PMMA substrate, we have measured optical properties in the range of visible light. As a results, the surface of nano structured PMMA showed a blue color according to induced the light. Furthermore, color intensity was increased according to increase the aspect ratio and diameter. In contrast, hierarchical micro-nano patterned surface showed iridescent colors.

Kortright, J. B., T. D. Nguyen, I. M. Tidswell e C. A. Lucas. "Substrate effects on x-ray specular reflectance and non-specular scattering from x-ray multilayers". In Physics of X-Ray Multilayer Structures. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/pxrayms.1992.tuc2.

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It is common knowledge that substrate roughness plays an important role in limiting the specular reflectance of x-ray multilayers. However, there have been relatively few systematic experimental studies of the effects of substrate roughness on x-ray multilayer reflectivity. We have begun to investigate these effects by measuring the specular and off-specular scattering from a set of substrates with different roughness and from tungsten/carbon multilayers deposited simultaneously onto an identical set of substrates.

Sobolev, V. V., J. M. Guilemany e J. A. Calero. "Formation of Structure of HVOF Sprayed WC-Co Coating on a Copper Substrate". In ITSC 1997, a cura di C. C. Berndt. ASM International, 1997. http://dx.doi.org/10.31399/asm.cp.itsc1997p0943.

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Abstract Mathematical modelling of the formation of the WC-Co coating structure and adhesion on copper substrate during high velocity oxygen-fuel (HVOF) spraying is provided. Smooth (polished) and rough (grit blasted) substrates are considered. Variations of solidification time, solidification velocity, thermal gradient, and cooling velocity in the coating and substrate interfacial region are studied. Formation of the amorphous and crystalline structures in the coating and of the crystalline structure in the substrate interfacial region is investigated. Behaviour of the crystal size and intercrystalline distance with respect to the thermal spray parameters and morphology of the substrate surface is analysed. Optimal conditions for the development of fine and dense crystalline structure are determined. Mechanical and thermal mechanisms of development of the substrate-coating adhesion are discussed. Results obtained agree well with experimental data.

Mori, Hiroyuki, Sayuri Kohara, Keishi Okamoto, Hirokazu Noma e Kazushige Toriyama. "Effects of Low CTE Materials on Thermal Deformation of Organic Substrates in Flip Chip Package Application". In ASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems collocated with the ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/ipack2015-48741.

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Coefficient of thermal expansion (CTE) characteristic of organic materials for substrates in flip chip package application demanded by semiconductor package requirements is becoming lower than ever. In general, height restrictions are imposed on package-on-package (PoP) devices in mobile applications. One should hence establish a tight budget on the height variation in manufacturing of the devices. Given such background, a lowering of the CTE characteristic of package substrates is an attractive solution for reducing package deformation upon manufacturing, since it contributes to minimize CTE mismatch of the substrates with silicon chips. In large-die flip chip applications such as high-end processors, a lower CTE substrate can mitigate mechanical stress not only on low-k layers in back end of the line (BEOL) underneath the chip bumps, but also on underfill layers during thermal cycling. Therefore an introduction of lower CTE materials in organic substrates is becoming essential for future applications of electronic devices. In this paper, thermal deformation behaviors of organic substrates associated with lowering of the CTEs of their constituent materials are analyzed by finite element analysis (FEA). The analyses are done on a 3-2-3 build-up layer structure substrate in order to focus onto typical application specific integrated circuit (ASIC) products. A finite element model for a test substrate is constructed by a method in which the substrate is divided into sections according to its circuitry patterns so that the lateral inhomogeneity of mechanical property is taken into account. The finite element analyses using the model showed that the package warpage decreases with lowering of the effective CTE of the substrate, but the warpage of the substrate itself increases and its surface profile changes from a concave shape to a convex shape. The analysis result of substrate warpage variation with the build-up material’s CTE showed that the selection of build-up materials with appropriate material properties can contribute to reduce the substrate warpage. The analysis also showed that the adverse impact to the substrate’s CTE reduction by such material selection is limited.

Leach, J. H., N. Biswas, T. Paskova, E. A. Preble, K. R. Evans, M. Wu, X. Ni, X. Li, Ü. Özgür e H. Morkoç. "Effect of substrate offcut on AlGaN/GaN HFET structures on bulk GaN substrates". In SPIE OPTO, a cura di Jen-Inn Chyi, Yasushi Nanishi, Hadis Morkoç, Joachim Piprek e Euijoon Yoon. SPIE, 2011. http://dx.doi.org/10.1117/12.875755.

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Mejia-Ariza, Juan M. "Substrate Prototype Development for Tensioned Phased Arrays". In 54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2013. http://dx.doi.org/10.2514/6.2013-1826.

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Eremina, Galina M., Alexey Yu Smolin e Sergey G. Psakhie. "Peculiarities of modeling of nanoindentation of coating-substrate system". In ADVANCED MATERIALS WITH HIERARCHICAL STRUCTURE FOR NEW TECHNOLOGIES AND RELIABLE STRUCTURES. AIP Publishing LLC, 2015. http://dx.doi.org/10.1063/1.4932740.

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Windt, D. L., W. K. Waskiewicz e J. Griffith. "The correlation between reflectance and surface roughness of multilayer X-ray optics". In Physics of X-Ray Multilayer Structures. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/pxrayms.1994.wb.2.

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High-efficiency, normal-incidence X-ray multilayer mirrors are now being used for a variety of practical applications. Among these is Extreme Ultraviolet (EUV) lithography. A practical EUV lithography printing tool may include as many as seven normal-incidence multilayer reflections, so it is imperative that the mirror substrates be fabricated with low surface roughness in order to achieve high reflectance, and consequently high system throughput (wafers/hour.) In order to develop the necessary techniques to fabricate such mirrors, it is first necessary to accurately quantify the surface finish requirements of the mirror substrates, and to then identify the surface finish metrology tools that can be used by the manufacturer during the substrate fabrication process. To this end, we have examined correlations between direct surface finish measurement techniques and normal-incidence, soft X-ray reflectance measurements of highly-polished X-ray multilayer mirrors.

Zhang, T., E. Padayodi, R. N. Raoelison e J. C. Sagot. "Development of Compatibilizing Sublayer for Metallizing CFRP Structures by Cold Spray". In ITSC2022. DVS Media GmbH, 2022. http://dx.doi.org/10.31399/asm.cp.itsc2022p0893.

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Abstract This study aims to develop a metal-based compatibilizing sublayer on a Carbon Fiber-Reinforced Polymer (CFRP) composite to overcome the erosion issue of polymer substrate using the cold spray deposition technique. The objective is to contribute to the in-situ repair of aircraft structures. Two cases of sublayers, i.e., Al-based sublayer (1126 μm thick) and Cu-based sublayer (547 μm thick), have been prepared and co-cured with the CFRP substrates by pressure assisted molding process. Gas-atomized copper powders were deposited on a reference sample of aluminum panel (A-0) and on two functionalized composite substrates (A-1 and C-1) by a high-pressure cold spraying (HPCS) process. The results show that cold spray deposition onto the Al-based sublayer leads to a coating formation whereas the Cu-based sublayer is strongly eroded by the supersonic collision of copper powders. Scanning electronic microscope (SEM) morphologies were used to investigate the HPCS deposition mechanisms on various configurations of substrates. It was found that the high deposition efficiency of case Cu/A-0 was achieved by metallic bonding, evidenced by the significant flattening powders and agglomeration phenomenon of multiple particles. The copper particles of case Cu/A-1, encapsulated by the deformed aluminum powders, could anchor to the substrate via mechanical interlocking, whereas only pure localized fracture of epoxy and exposed broken carbon fibers were observed on the substrate of case Cu/C-1. The results demonstrated the feasibility of an Al-based sublayer-assisted cold spray process for the thermosetting CFRP composite to achieve a successful deposition of copper powders, which also emphasized the necessity to search an optimal material coupling between sublayers and coatings.

Schlegel, N., S. Ebert, G. Mauer e R. Vaßen. "Columnar Structured Thermal Barrier Coatings (TBCs) by Suspension Plasma Spraying (SPS)". In ITSC 2014, a cura di R. S. Lima, A. Agarwal, M. M. Hyland, Y. C. Lau, G. Mauer, A. McDonald e F. L. Toma. DVS Media GmbH, 2014. http://dx.doi.org/10.31399/asm.cp.itsc2014p0113.

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Abstract In this study, a suspension containing Mg-Al-spinel nanopowder was deposited on bond-coated IN738 and stainless steel disks by suspension plasma spraying with and without substrate cooling. Coating surfaces and cross-sections were examined by SEM, EDS, and XRD analysis and thermal cycling tests were performed. SEM images of coatings obtained on cooled stainless steel show a unique columnar microstructure with a cauliflower-like surface. XRD spectra of the nanopowder and coatings revealed evidence of phase changes in the material deposited on cooled substrates. In preparing samples for thermal cycling tests, a YSZ layer was deposited on bond-coated IN738 prior to spraying the suspension. Double-layered Mg-Al-spinel/YSZ thermal barrier coatings produced on cooled substrates exhibited a thermal cycling lifetime of 2000 cycles at 1390°C, compared to 101 cycles for the TBCs sprayed without substrate cooling. The superior performance of the TBCs sprayed with substrate cooling is attributed to the densification of the coatings, revealed by SEM images, and possibly the formation of CaO-6Al2O3 needles and Al2O3 precipitates as identified by EDS measurements.

Rapporti di organizzazioni sul tema "Substrats structurés":

Melde, Kathleen L. Exploring New RF Circuit Structures with Embedded Patterned Substrate Layers. Fort Belvoir, VA: Defense Technical Information Center, giugno 2013. http://dx.doi.org/10.21236/ada616694.

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Sardana, Neha, Heena Sammi e Rajesh V. Nair. Reusable SERS substrate based on interconnected metal network structure. Peeref, giugno 2023. http://dx.doi.org/10.54985/peeref.2306p3513910.

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Elbaum, Michael, e Peter J. Christie. Type IV Secretion System of Agrobacterium tumefaciens: Components and Structures. United States Department of Agriculture, marzo 2013. http://dx.doi.org/10.32747/2013.7699848.bard.

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Objectives: The overall goal of the project was to build an ultrastructural model of the Agrobacterium tumefaciens type IV secretion system (T4SS) based on electron microscopy, genetics, and immunolocalization of its components. There were four original aims: Aim 1: Define the contributions of contact-dependent and -independent plant signals to formation of novel morphological changes at the A. tumefaciens polar membrane. Aim 2: Genetic basis for morphological changes at the A. tumefaciens polar membrane. Aim 3: Immuno-localization of VirB proteins Aim 4: Structural definition of the substrate translocation route. There were no major revisions to the aims, and the work focused on the above questions. Background: Agrobacterium presents a unique example of inter-kingdom gene transfer. The process involves cell to cell transfer of both protein and DNA substrates via a contact-dependent mechanism akin to bacterial conjugation. Transfer is mediated by a T4SS. Intensive study of the Agrobacterium T4SS has made it an archetypal model for the genetics and biochemistry. The channel is assembled from eleven protein components encoded on the B operon in the virulence region of the tumor-inducing plasmid, plus an additional coupling protein, VirD4. During the course of our project two structural studies were published presenting X-ray crystallography and three-dimensional reconstruction from electron microscopy of a core complex of the channel assembled in vitro from homologous proteins of E. coli, representing VirB7, VirB9, and VirB10. Another study was published claiming that the secretion channels in Agrobacterium appear on helical arrays around the membrane perimeter and along the entire length of the bacterium. Helical arrangements in bacterial membranes have since fallen from favor however, and that finding was partially retracted in a second publication. Overall, the localization of the T4SS within the bacterial membranes remains enigmatic in the literature, and we believe that our results from this project make a significant advance. Summary of achievements : We found that polar inflations and other membrane disturbances relate to the activation conditions rather than to virulence protein expression. Activation requires low pH and nutrient-poor medium. These stress conditions are also reflected in DNA condensation to varying degrees. Nonetheless, they must be considered in modeling the T4SS as they represent the relevant conditions for its expression and activity. We identified the T4SS core component VirB7 at native expression levels using state of the art super-resolution light microscopy. This marker of the secretion system was found almost exclusively at the cell poles, and typically one pole. Immuno-electron microscopy identified the protein at the inner membrane, rather than at bridges across the inner and outer membranes. This suggests a rare or transient assembly of the secretion-competent channel, or alternatively a two-step secretion involving an intermediate step in the periplasmic space. We followed the expression of the major secreted effector, VirE2. This is a single-stranded DNA binding protein that forms a capsid around the transferred oligonucleotide, adapting the bacterial conjugation to the eukaryotic host. We found that over-expressed VirE2 forms filamentous complexes in the bacterial cytoplasm that could be observed both by conventional fluorescence microscopy and by correlative electron cryo-tomography. Using a non-retentive mutant we observed secretion of VirE2 from bacterial poles. We labeled the secreted substrates in vivo in order detect their secretion and appearance in the plant cells. However the low transfer efficiency and significant background signal have so far hampered this approach.

Hoitink, Harry A. J., Yitzhak Hadar, Laurence V. Madden e Yona Chen. Sustained Suppression of Pythium Diseases: Interactions between Compost Maturity and Nutritional Requirements of Biocontrol Agents. United States Department of Agriculture, giugno 1993. http://dx.doi.org/10.32747/1993.7568755.bard.

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Several procedures were developed that predict maturity (stability) of composts prepared from municipal solid wastes (MSW). A respirometry procedure, based O2 uptake by compost, predicted (R2=0.90) the growth response of ryegrass in composts and an acceptable level of maturity. Spectroscopic methods (CPMAS13-NMR and DRIFT spectroscopy) showed that the stabilizing compost contained increasing levels of aromatic structures. All procedures predicted acceptable plant growth after approximately 110 days of composting. MSW compost suppressed diseases caused by a broad spectrum of plant pathogens including Rhizoctonia solani, Pythium aphanidermatum and Fusarium oxysporum. A strain of Pantoea agglomerans was identified that caused lysis of hyphae of R. solani. Evidence was obtained, suggesting that thermophilic biocontrol agents also might play a role in suppression. 13C-NMR spectra revealed that the longevity of the suppressive effect against Pythium root rot was determined by the concentration of readily biodegradable carbohydrate in the substrate, mostly present as cellulose. Bacterial species capable of inducing biocontrol were replaced by those not effective as suppression was lost. The rate of uptake of 14C-acetate into microbial biomass in the conducive substrate was not significantly different from that in the suppressive substrate although specific activity was higher. The suppressive composts induced systemic acquired resistance in cucumjber roots to Pythium root rot and to anthracnose in the foliage. Composts also increased peroxidase activity in plants by the conducive substrate did not have these effects. In summary, the composition of the organic fraction determined bacterial species composition and activity in the substrate, which in turn regulated plant gene expression relative to biological control.

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Mohanty, Shaktiranjan, Minaxi Sharma, Ashish Kumar Moharana, Brindaban Ojha, Esita Pandey, Braj Bhusan Singh e Subhankar Bedanta. Magnetization Reversal and Domain Structures in Perpendicular Synthetic Antiferromagnets Prepared on Rigid and Flexible Substrates. Peeref, ottobre 2022. http://dx.doi.org/10.54985/peeref.2210p5225446.

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Timko, Michael P. Structural domains in NADPH: Protochlorophyllide oxidoreductases involved in catalysis and substrate binding. Final report. Office of Scientific and Technical Information (OSTI), settembre 1999. http://dx.doi.org/10.2172/766046.

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Kirchner, Kevin. Status of Structural Analysis of Substrates and Film Growth Inputs for GaN Device Development Program. Fort Belvoir, VA: Defense Technical Information Center, gennaio 2011. http://dx.doi.org/10.21236/ada535676.

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Morton, S. A., G. D. Waddill, M. Spangenberg, E. A. Seddon, J. Neal, T. Shen e J. G. Tobin. Spin-Resolved Electronic Structure of Ultrathin Epitaxial Fe Films on Vicinal and Singular GaAs(100) Substrates. Office of Scientific and Technical Information (OSTI), marzo 2003. http://dx.doi.org/10.2172/15007312.

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Yang, Nacy Y. C. Effect of Substrate Configuration on the Grain Structure and Morphology of Electrodeposited Ni for Prototyping LIGA. Office of Scientific and Technical Information (OSTI), luglio 2002. http://dx.doi.org/10.2172/797427.

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