Дисертації: "Structure formation mechanism"

1

Weddell, Derek Alexander. "Synthesis, structure determination and mechanism in thiophene derivatives." Thesis, Nottingham Trent University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343542.

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2

Liu, Xuejie. "Basic structure and formation mechanism of Ti-Si-N superhard nanocomposite coatings." Heimsheim : Jost-Jetter, 2009. http://d-nb.info/994974574/34.

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3

Liu, Xuejie. "Basic structure and formation mechanism of Ti-Si-N superhard nanocomposite coatings." Heimsheim Jost-Jetter, 2008. http://d-nb.info/99307751X/04.

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4

Stegelmeier, Corinna [Verfasser], and Stephan [Akademischer Betreuer] Förster. "Structure Formation Mechanism of Isoporous Block copolymer Membranes / Corinna Stegelmeier. Betreuer: Stephan Förster." Bayreuth : Universität Bayreuth, 2015. http://d-nb.info/1077247427/34.

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5

Harkema, Stephan. "Capillary instabilities in thin polymer films mechanism of structure formation and pattern replication /." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 2006. http://irs.ub.rug.nl/ppn/291147801.

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6

艶艶, 陳., and Yanyan Chen. "Integrated studies on structure and formation mechanism of environmental consciousness in rural and urban China." Thesis, https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB12977312/?lang=0, 2016. https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB12977312/?lang=0.

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中国における都市部と農村部異なる制度的・社会経済的背景により、独特な環境意識を生まれていると考えられる。本研究は、現地調査によりデータを収集し、統計分析を駆使したことにより、都市部と農村部における環境意識の特有の構造と形成メカニズムを解明することを目的とする。先行研究の成果を踏まえ、都市部と農村部の社会構造を考慮し、環境意識に関する総合的な理論モデルを提案し、環境意識の三つのディメンションに分けて展開する。理論的に検討することと実証的なデータの分析結果を基に、環境意識形成の内在因子と外部影響要因を明らかにした。
Long-time institutional and socioeconomic segmentations make rural China become a distinctive society from the urban China. The remarkable rural and urban division in China supplies us a good context to explore the formation and diverse social facets of environmental consciousness. This study aims to clarify the specific structure and formation mechanism of environmental consciousness under the different social backgrounds of rural and urban China based on the statistical results derived from survey data. Three dimensions of environmental consciousness and an integrated theoretical framework which involves both social structural and social psychological variables are proposed. Based on the proposed theoretical framework and examined data analyses, the inner causes and externally influencing factors of environmental consciousness were clarified.
博士(文化情報学)
Doctor of Culture and Information Science
同志社大学
Doshisha University

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7

Соловйова, Олександра Омелянівна, Александра Емельяновна Соловьева, and Oleksandra Omelianivna Soloviova. "Simulation of the Mechanism of Defect Structure Formation in Polycrystalline Indium Oxide Under Ion Irradiation." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35411.

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The structural changes in polycrystalline indium oxide were studied before and after irradiation of samples, Xe+ ions with energy 140 and 300 keV, X-ray methods. Discovery, that irradiation leads to a change in the chemical composition of the oxide, accompanied by phase transformations. The main structure of the cubic oxide after irradiation contain macro and micro stresses, which depend on the energy irradiation. The increase in the relative integral intensity of radiation reflected from the planes of the cell on depth was observed. The maximum value observed at a depth of 1.5 m from the plane (510). The analyses of reflected the radiation found that the flux of photons remains constant - the atomic nuclei of oxide not change, increases the frequency, decreases the wavelength depend from the energy irradiation. In some directions in reflecting from the planes, the atoms are formed with different electron density, that connect whit presence of defects, which leads to appear of the forced oscillation, which increases the relative integral intensity of the reflected radiation. These processes are damped with increasing depth of the sample. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35411

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8

Liu, Xuejie [Verfasser]. "Basic structure and formation mechanism of Ti-Si-N superhard nanocomposite coatings / vorgelegt von Xuejie Liu." Heimsheim : Jost-Jetter, 2009. http://d-nb.info/994974574/34.

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9

Tungchaiwattana, Somjit. "A study of particle structure and film formation mechanism on the mechanical properties of synthetic rubber films." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/a-study-of-particle-structure-and-film-formation-mechanism-on-the-mechanical-properties-of-synthetic-rubber-films(3014e013-bc99-4fbf-8282-5d13ed4251b3).html.

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This thesis investigated a new group of poly(Bd)/poly(Bd-co-MAA) core-shell particles that were ionically crosslinked and cast as nanostructured ionomer films from aqueous dispersions. The new group of poly(Bd)/poly(Bd-co-MAA) core-shell particles were studied for structure-property relationships and morphology. The covalent crosslinking content in the core and the shell were varied at constant ionic crosslinking. Stress-strain data showed control of the nanostructured films. The chain transfer agent used during the preparation of the nanoparticles core-shells was shown to independently tune the mechanical properties of the films.

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10

Virtanen, Otto L. J. [Verfasser], Walter [Akademischer Betreuer] Richtering, and Sebastian [Akademischer Betreuer] Seiffert. "Insight into precipitation polymerization of N-isopropylacrylamide : reaction mechanism, particle formation and particle structure / Otto L. J. Virtanen ; Walter Richtering, Sebastian Seiffert." Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1130792501/34.

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11

Deng, Qingming. "Computational analysis of electronic properties and mechanism of formation of endohedral fullerenes and graphene with Fe atoms." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-203016.

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In this thesis, a series of computational studies based on density functional theory (DFT) and density functional tight-binding (DFTB) is presented to deeply understand experimental results on the synthesis of endohedral fullerenes and graphene/iron hybrids at atomic level. In the ﬁrst part, a simple and efficient model is proposed to evaluate the strain experienced by clusters encapsulated in endohedral metallofullerenes (EMFs). Calculations for the sole cluster, either in the neutral or the charged state, cannot be used for this goal. However, when the effect of the carbon cage is mimicked by small organic π-systems (such as pentalene and sumanene), the cluster has sufficient freedom to adopt the optimal configuration, and therefore the energetic characteristics of the EMF-induced distortion of the cluster can be evaluated. Both nitride and sulfide clusters were found to be rather flexible. Hence, they can be encapsulated in carbon cages of different size and shape. For carbide M2C2 cluster the situation is more complex. The optimized cluster can adopt either butterfly or linear shapes, and these configurations have substantially different metal-metal distance. Whereas for Sc2C2 both structures are isoenergetic, linear form of the Y2C2 cluster is substantially less stable than the butterfly-shaped configuration. These results show that phenomenon of the “nanoscale fullerene compression” once proposed by Zhang et al. (J. AM. CHEM. SOC. (2012),134(20)) should be “nanoscale fullerene stretching”. Finally, the results also reveal that both Ti2S and Ti2C2 cluster are strained in corresponding EMF molecules, but the origin of the strain is opposite: C78-D3h(5) cage imposes too long Ti···Ti distance for the sulfide cluster and too short distance for the carbide cluster. In the second part of the thesis, possible fullerene geometries and electronic structures have been explored theoretically for the species detected in mass spectra of the Sc-EMF extract synthesized using CH4 as a reactive gas. Two most promising candidates, namely Sc4C@C80-Ih(7) and Sc4C3@C80-Ih(7), have been identified and further studied at the DFT level. For Sc4C@C80, the tetrahedral Sc4 cluster with the central μ4-C atom was found to be 10 kJ/mol more stable than the square cluster. For Sc4C3@C80, the calculation showed that the most stable is the Sc4C3 cluster in which the triangular C3 moiety is η3- and η2-coordinated to Sc atoms. Whereas Sc4C@C80 has rather small HOMO-LUMO gap and low ionization potential, the HOMO-LUMO gap of Sc4C3@C80 is substantially higher and exceeds that of Sc4C2@C80. In the third part, computational studies of structures and reactivity are described for a new type of EMFs with a heptagon that has been produced in the arc-discharge synthesis. DFT computations predict that LaSc2N@Cs(hept)-C80 is more stable than LaSc2N@D5h-C80, so the former should be synthesized in much higher yield than observed. This disagreement may be ascribed to the kinetic factors rather than thermodynamic stability. Because of prospective applications of this EMFs by introducing functional groups, the influence of the heptagon on the chemical properties have been further evaluated. Thermodynamically and kinetically preferred reaction sites are studied computationally for Prato and Bingel-Hirsch cycloaddition reactions. In both types of reactions the heptagon is not affected, and chemical reactivity is determined by the adjacent pentalene units. Thermodynamically controlled Prato addition is predicted to proceed regioselectively across the pentagon/pentagon edges, whereas the most reactive sites in kinetically-controlled Bingel-Hirsch reaction are the carbon atoms next to the pentagon/pentagon edge. Fourth, although various EMFs have been successfully synthesized and characterized, the formation mechanism is still not known in details, and hence control of the synthesis products is rather poor. Therefore, EMF self-assembly process in Sc/carbon vapor in the presence and absence of cooling gas (helium) and reactive gas (NH3 and CH4) is systematically investigated using quantum chemical molecular dynamics (QM/MD) simulations based on the DFTB potentials. The cooling gas effect is that the presence of He atoms accelerates formation of pentagons and hexagons and reduces the size of formed carbon cages in comparison to the analogous He-free simulations. As a result, the Sc/C/He system yields a large number of successful trajectories (i.e. leading to the Sc-EMFs) with more realistic cage-size distribution than the Sc/C system. Encapsulation of Sc atoms within the carbon cage was found to proceed via two parallel mechanisms. The main mechanism involves nucleation of the several hexagons and pentagons with Sc atoms already at the early stages of the carbon vapor condensation. In such proto-cages, both Sc–C σ-bonds and coordination bonds between Sc atoms and the π-system of the carbon network are present. Sc atoms are thus rather labile and can move along the carbon network, but the overall bonding is sufficiently strong to prevent dissociation even at high temperatures. Further growth of the carbon cage results in encapsulation of one or two Sc atoms within the forming fullerene. Another encapsulation mechanism is observed in rare cases. In this process, the closed cage is formed with Sc being a part of the carbon network, i.e. being bonded by three or four Sc–C σ-bonds. However, such intermediates are found to be unstable, and transform into the endohedral fullerenes within few picoseconds of annealing. In perfect agreement with experimental studies, extension of the simulation to Fe and Ti showed that Fe-EMFs are not formed at all, whereas Ti is prone to form Ti-EMFs with small cage sizes, including Ti@C28-Td and Ti@C30-C2v(3). The role of “reactive gas” in the EMF synthesis is revealed in dedicated simulations of the fullerene formation in the presence of several molecules of CH4 or NH3. When concentration of reactive gas is high, carbon vapor tends to form graphene flakes or other carbon species terminated by hydrogen atoms, whereas the yield of empty fullerenes is very low. Conversely, with additional metal atoms (Sc) and the same number of NH3 molecules, the yield of fullerenes constantly increase from 5 to 65% which is ascribed to the catalytic activity of metal atoms in the nucleation of carbon cages already at early stage. Moreover, due to the presence of hydrogen atoms from the reactive gas, the carbon cage formation requires much longer time, which provides sufficient reaction time to encapsulate 3 or 4 Sc atoms within one cage. It explains preferential formation of clusterfullerenes in experiments with reactive gas. At the same time, monometallofullerenes and dimetallofullerenes are the main products in absence of reactive gas. We also provide possible growth mechanisms of carbide and cyano-clusterfullerenes in details to elucidate how the intracluster goes into the cage. A possible growth mechanism of nitride clusterfullerenes has been proposed based on DFT results. In the last part, a free-standing crystalline single-atom thick layer of Fe has been studied theoretically. By investigating the energy difference, ΔE, between a suspended Fe monolayer and a nanoparticle using the equivalent number of Fe atoms, one can estimate that the largest stable membrane should be ca. 12 atoms wide or 3 × 3 nm2 which is in excellent agreement with the experimental observation. Otherwise, the possibility of C, O, N atoms embedded into the Fe membrane can been fully excluded by DFTB and DFT simulations, which agrees with electron energy loss spectroscopy (EELS) measurement. A significantly enhanced magnetic moment for single atom thick Fe membranes (3.08 μB) is predicted by DFT as compared to the bulk BCC Fe (2.1 μB), which originates from the 2D nature of the Fe membrane since the dz2 orbital is out-of-plane while the dxy orbital is in-plane.

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12

Grégoire, Brian. "Relation Composition-Structure des Hydroxydes Doubles Lamellaires : Effets de la charge du feuillet et de la nature de l'anion interfoliaire." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0154/document.

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Ce travail de thèse s'intéresse à la relation entre la composition des phases Hydroxydes Doubles Lamellaires (HDL) et leurs propriétés structurales. La première partie de ce manuscrit est consacrée à la formation et aux propriétés structurales de ces matériaux. L'effet de la nature des cations (MgII, NiII, CoII ; AlIII, FeIII) et de leur stoechiométrie dans le feuillet (MII/MIII E [2 ; 10]) constitue les axes principaux de ces travaux. L'étude du comportement hydrolytique d'un mélange de cations divalents et trivalents en fonction de leurs proportions en solution a permis de proposer un mécanisme topotactique de formation de ces phases HDL. Il a aussi été montré que la variabilité stoechiométrique du feuillet ne dépend que de la nature des cations. Ainsi, des modèles électrostatiques ont été proposés afin de rationaliser et prédire la gamme de composition de ces phases HDL en fonction de la nature des cations. La seconde partie est dédiée aux propriétés du milieu interfoliaire. Une étude couplant des analyses par spectroscopies vibrationnelles infrarouge et Raman et par diffraction des Rayons X a permis d'apporter une description précise de l'influence de la nature des cations, et de leurs stoechiométries sur l'organisation des anions dans le milieu interfoliaire (Cl-, CO32-, NO3-, ClO4-, acides aminés). Le rôle de l'eau dans ces phases a également été étudié. Dans le cas des hybrides organo-minéraux, il a été montré que la charge dicte l'orientation des acides aminés intercalées et par conséquent, leur réactivité envers la formation de la liaison peptidique. Également, les propriétés énantioselectives du domaine interfeuillet sont mises en avant pour la formation de peptides
This manuscript is devoted to the comprehension of the relationship between the composition of Layered Double Hydroxides (LDH) and their structural properties. The first part of this manuscript is focalized on the formation and the structural properties of these materials. The influence of the cationic nature (MgII, NiII, CoII ; AlIII, FeIII) and their stoichiometries within the layer (MII/MIII E [2 ; 10]) constitutes the main axis of these investigations. The study of the hydrolytic behavior of a solution containing a mixture of divalent and trivalent cations as a function of their relative proportion allowed to propose a topotactic mechanism of formation of LDH phases. Moreover, it has been showed that the composition range is solely dependent on the nature of the cations. Thus, electrostatic models were designed to rationalize and predict the composition range as a function of the cationic nature. The second part is concerned with the properties of the interlayer domain. A joint study, coupling vibrational spectroscopies (Infrared and Raman) and X-ray diffraction allowed a detailed description of the influence of the cations and their stoichiometries on the organization of the interlayer anions (Cl-, CO32-, NO3-, ClO4-, aminoacids). The role of the interlayer water has also been investigated. Concerning hybrid organo-minerals, it has been showed that the layer charge dictates the orientation of the interlayered aminoacids, and consequently, their reactivity toward the formation of the peptide bonds. The enantioselective properties of the interlayer domain are highlighted toward the formation of peptides

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13

Bouhafid, Abdelmounaim. "Contribution a l'etude du rayonnement de feu de nappe de combustible liquide : cas d'un feu de kerosene." Poitiers, 1987. http://www.theses.fr/1987POIT2317.

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Etude du rayonnement des flammes de diffusions libres susceptibles de se developper sur une surface de dimension restreinte (cuve circulaire de 15cm de diametre) de kerosene. Les transferts en retour vers la base du foyer source et des cibles de l'environnement immediat sont pris en compte. Les proprietes radiatives des flammes et la formation des suies dans la flamme sont etudiees. Un modele mathematique est utilise pour calculer les flux rayonnes des flammes. Sa validite et son niveau d'applicabilite sont determines

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14

Lefebvre, Laurent. "Étude de la pré-formation de particules α dans les noyaux de 40Ca et d'40Ar par cassure nucléaire". Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00875639.

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Le noyau est un objet quantique complexe formé de protons et neutrons. Dans l'approche champ moyen, les nucléons sont considérés comme des particules indépendantes évoluant dans un potentiel moyen. Cependant dans certaines conditions, des nucléons peuvent se regrouper pour former des amas ou " clusters ".Pour comprendre ce phénomène de " clusters " dans les noyaux, nous avons étudié la structure dans l'état fondamental du 40Ca et de l'40Ar. En effet, des calculs théoriques tendent à montrer que les noyaux N = Z pourraient plus facilement adopter une structure en " clusters " que les noyaux N ≠ Z en raison d'un plus grand recouvrement des fonctions d'onde des neutrons et protons. Dans ce cas, l'émission de particules α par les noyaux N = Z sous l'effet du potentiel nucléaire attractif d'un noyau projectile, appelée " Towing-Mode " sera plus important que pour un noyau N ≠ Z. Dans ce but, nous avons réalisé une expérience au GANIL utilisant un faisceau d'40Ar à 35 MeV/A et une cible de 40Ca. Le spectromètre SPEG a permis d'identifier avec une très bonne résolution les ions lourds produits durant la réaction. Les détecteurs silicium MUST2 furent placés tout autour de la cible pour mesurer les particules α émises par la cible et le projectile et le prototype de calorimètre EXL fut utilisé pour la détection des photons de décroissance des noyaux résiduels d'36Ar et de 36S.Un modèle théorique basé sur la résolution de l'équation de Schrödinger dépendante du temps (TDSE) a été utilisé pour reproduire certains résultats expérimentaux comme les distributions angulaires. L'analyse des données a permis de reconstruire des spectres d'énergies d'excitation et des sections efficaces différentielles. De la comparaison entre ces distributions expérimentales et celles calculées par le modèle théorique, nous avons pu extraire des facteurs spectroscopiques Sα pour les deux noyaux d'intérêt. Les taux de " clusterisation " observés pour ces deux noyaux semblent indiquer que la structure en " clusters " n'est pas plus favorisée dans le 40Ca que dans l'40Ar.

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15

Шадріна, Галина Миколаївна. "Склокристалічні покриття по сплавах титану в системі R₂O – RO – RO₂ – R₂O₃ – P₂O₅ – SіO₂ для кісткового ендопротезування". Thesis, НТУ "ХПІ", 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/21953.

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Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.17.11 – технологія тугоплавких неметалічних матеріалів. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2016 р. Дисертацію присвячено розробленню основ технології одержання склокристалічних покриттів по сплавах титану на основі системи R₂O – RO – RO₂ – R₂O₃ – P₂O₅ – SіO₂ для кісткового ендопротезування. Сформульовано наукові положення одержання кальційсилікофосфатних склокристалічних покриттів як біоактивних компонентів ендопротезів кульшового суглобу та нижньої шелепи. Обрано вихідну склоутворюючу систему та встановлено механізм структуро- і фазоутворення в модельних стеклах та особливості формування на їх основі покриттів по сплавах титану під час термічної обробки. Розроблено технологію одержання біоактивних склокристалічних покриттів з мікро-твердістю H = 6620 ÷ 7050 МПа, параметром тріщиностійкості K1C = 2,01 ÷ 2,73 МПа·м1/2, твердістю за Віккерсом HV = 5440 ÷ 5660 МПа, адгезійною міцністю σадг = 16 ÷ 17 МПа та підтверджено формування апатитоподібного шару на поверхні розроблених покриттів in vitro, що дозволяє використовувати їх в умовах змінних динамічних навантажень.
Thesis for the Candidate of Technical Sciences Degree n specialty 05.17.11 – Technology of refractory nonmetallic materials. – National Technical University "Kharkiv Polytechnical Institute", Kharkiv, 2016. The thesis is dedicated to development of technological bases of obtaining glass-ceramic coatings on titanium alloys in the R₂O – RO – RO₂ – R₂O₃ – P₂O₅ – SіO₂ system for bone endoprostheses. Scientific provisions of obtaining calcium silicophos-phate glass-ceramic coatings as bioactive components of endoprostheses of coxofemo-ral joint and lower jaw bone were defined. Initial glass-forming system was chosen, mechanism of structure- and phase-formation in model glasses and characteristics of coatings formation on their base on titanium alloys during thermal treatment has been established. Technology of bioactive glass-ceramic coatings with microhardness of H = 6620 ÷ 7050 MPa, crack toughness parameter K1C = 2,01 ÷ 2,73 MPa·м1/2, Vickers hardness HV = 5440 ÷ 5660 MPa, adhesive strength σadh 16 ÷ 17 MPa has been developed, formation of apatite-like layer on the surface of developed coatings in vitro has been confirmed which allows their use in conditions of conditions of variable dynamic loads.

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16

Шадріна, Галина Миколаївна. "Склокристалічні покриття по сплавах титану в системі R₂O – RO – RO₂ – R₂O₃ – P₂O₅ – SіO₂ для кісткового ендопротезування". Thesis, НТУ "ХПІ", 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/21952.

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Анотація:

Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.17.11 – технологія тугоплавких неметалічних матеріалів. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2016 р. Дисертацію присвячено розробленню основ технології одержання склокристалічних покриттів по сплавах титану на основі системи R₂O – RO – RO₂ – R₂O₃ – P₂O₅ – SіO₂ для кісткового ендопротезування. Сформульовано наукові положення одержання кальційсилікофосфатних склокристалічних покриттів як біоактивних компонентів ендопротезів кульшового суглобу та нижньої шелепи. Обрано вихідну склоутворюючу систему та встановлено механізм структуро- і фазоутворення в модельних стеклах та особливості формування на їх основі покриттів по сплавах титану під час термічної обробки. Розроблено технологію одержання біоактивних склокристалічних покриттів з мікро-твердістю H = 6620 ÷ 7050 МПа, параметром тріщиностійкості K1C = 2,01 ÷ 2,73 МПа·м1/2, твердістю за Віккерсом HV = 5440 ÷ 5660 МПа, адгезійною міцністю σадг = 16 ÷ 17 МПа та підтверджено формування апатитоподібного шару на поверхні розроблених покриттів in vitro, що дозволяє використовувати їх в умовах змінних динамічних навантажень.
Thesis for the Candidate of Technical Sciences Degree n specialty 05.17.11 – Technology of refractory nonmetallic materials. – National Technical University "Kharkiv Polytechnical Institute", Kharkiv, 2016. The thesis is dedicated to development of technological bases of obtaining glass-ceramic coatings on titanium alloys in the R₂O – RO – RO₂ – R₂O₃ – P₂O₅ – SіO₂ system for bone endoprostheses. Scientific provisions of obtaining calcium silicophos-phate glass-ceramic coatings as bioactive components of endoprostheses of coxofemo-ral joint and lower jaw bone were defined. Initial glass-forming system was chosen, mechanism of structure- and phase-formation in model glasses and characteristics of coatings formation on their base on titanium alloys during thermal treatment has been established. Technology of bioactive glass-ceramic coatings with microhardness of H = 6620 ÷ 7050 MPa, crack toughness parameter K1C = 2,01 ÷ 2,73 MPa·м1/2, Vickers hardness HV = 5440 ÷ 5660 MPa, adhesive strength σadh 16 ÷ 17 MPa has been developed, formation of apatite-like layer on the surface of developed coatings in vitro has been confirmed which allows their use in conditions of conditions of variable dynamic loads.

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17

Walker, David. "Structural mechanisms of sheet formation in papermaking systems." Thesis, University of Manchester, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305584.

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18

Carter-Fenk, Kimberly Anne. "Structure, Adsorption Mechanisms, and Vibrational Exciton Formation at Proxy Marine Interfaces." The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1617809603306859.

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19

Gao, Chuanbo. "Formation mechanism of anionic-surfactant-templated mesoporous silica (AMS)." Doctoral thesis, Stockholm : Department of Physical, Inorganic and Structural Chemistry, Stockholm University, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-29628.

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20

Behfar, Stefan kambiz. "Network, clusters and innovations : 3 essays." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAB002.

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[...] Mes travaux portent sur les clusters structurant le réseau et l'innovation car 1) le cluster impacte collectivement plutôt qu’individuellement la sortie du réseau, 2) les couplages intra et inter-cluster représentent la structure même des clusters mais ils influencent différemment l'innovation ou la croissance du cluster, 3) un certain compromis reste à définir entre la structure dense et éparse des différents réseaux. Un cluster est de façon générale défini comme un groupe de choses similaires ou de personnes qui travaillent sur des sujets analogues. Selon le domaine auquel il s’applique, même si l’idée reste la même, la définition s’affine. En sciences des organisations, un cluster représente un regroupement d’entreprises et d’institutions qui interagissent entre-elles par le biais de contrats, d’opérations formelles ou informelles et de réunions occasionnelles afin de contribuer collectivement à un résultat innovant. [...] La thèse est structurée comme suit. Dans l'introduction générale, nous passons en revue la littérature des connaissances existantes qui sert de base pour le cadre conceptuel des documents. Nous définissons ensuite certains concepts utilisés dans les trois articles présentés tels que la structure de réseau complexe (utilisée dans le premier article), l'innovation et les liens de réseau (utilisés principalement dans le deuxième article), et la gestion des connaissances utilisées (dans le troisième article). Dans le premier article, nous discutons les différents mécanismes de formation de liens dictés par les réseaux dirigés permettant de distinguer la distribution des degrés. Dans le deuxième article, nous abordons l'impact de la dynamique de groupe sur l'innovation du groupe de projet OSS. Dans le troisième article, nous nous attachons à l'impact du transfert des connaissances à l'intérieur des groupes sur le transfert des connaissances entre les groupes. L'annexe A permettra de discuter la modélisation analytique de la croissance des réseaux sociaux en utilisant la projection de réseaux multicouches ; l'annexe B sera l’occasion de présenter statistiquement le lien entre les relations intragroupe et les relations intergroupe
[...] However, there is a gap in the literature with regard to the analysis of cluster or group structure as an input and cluster or group innovation as an output, e.g. “impact of network cluster structure on cluster innovation and growth”, i.e. how intra- and inter-cluster coupling, structural holes and tie strength impact cluster innovation and growth; and how intra-cluster density affects inter-cluster coupling; that I address in my thesis.Therefore, I focus on the cluster (or group of individuals) rather than the individual to analyze both network structure and innovation, because 1) clusters represent collective impact on network output rather than individuals’ impact, 2) intra and inter cluster couplings both represent cluster structure but have different impacts on cluster innovation and growth, 3) trade-offs among dense and sparse network cluster structures are different from those associated with networks of individuals. [...] The thesis is structured as follows. In the general introduction, I review the literature of existing knowledge in the field, which serves as a basis for the conceptual framework for the papers. I then define certain concepts used in the papers, such as complex network structure used in the first paper, innovation and network ties mainly used in the second paper, and knowledge management used in the third paper. In the first paper I discuss directed networks’ different link formation mechanisms causing degree distribution distinction. In the second paper, I discuss the impact of group dynamics on OSS project group innovation. In the third paper, I discuss impact of knowledge transfer inside groups onto knowledge transfer between groups. In appendix A, I discuss analytical modeling of social network growth using multilayer network projection; and in appendix B, I discuss statistically how intragroup ties and intergroup ties are related

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21

Henderson, Alistair Paul. "Structures and mechanisms of formation of adducts of glutaraldehyde and succinaldehyde with amines." Thesis, University of Newcastle Upon Tyne, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324799.

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22

Su, Lusheng. "Formation Mechanism and Thermoelectric Energy Conversion of Titanium Dioxide Nanotube Based Multi-Component Materials and Structures." University of Toledo / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1370793126.

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23

Barbosa, Alba ValÃria de Oliveira. "Investigation of the internal deformation mechanism (formation of holes) of sponge cakes diet." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=12628.

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FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico
The development of cakes with a reduced sugar content is to attain the market for people with restriction sugar, or who choose to healthier products however, the sugar not only exerts the characteristic sweetness, but also controls the main phenomena responsible for the formation of structural cakes, thus reducing their losses because the structure of the cakes. The objective of the study was to investigate the possible causes of internal deformation (formation of holes) in sponge cakes with reduced calorie. Seven formulations were developed with increasing substitution of sugar for sweeteners solutions (sucralose / acesulfame K) and xanthan gum. Were produced without wheat flour, which flour has been replaced entirely of gluten powder to verify that only the starch contributes to the deformations presented. Later cakes were produced using wheat flour, with the objective of evaluating the effects of replacing sugar to sweeteners for solutions of xanthan gum on the thermal properties of starch gelatinization and apparent viscosity of the dough cakes. The results of cake wheat flour without demonstrated that replacement of the sugar and sweeteners solutions of xanthan gum, negatively interfering on the functions of the proteins, ruling out the possibility that the starch is the sole agent to contribute with the observed deformations. The results of cakes produced with wheat flour indicated that the use of sweeteners and xanthan gum as a sugar substitute exhibited a higher capacity than sugar and starch to bind water system, raising the temperature (To and Tp) and enthalpies gelatinization resulting in the decrease of the degree of gelatinization and the appearance of dark zones, which appears to have been caused by the the accumulation of compounds of Maillard reaction. The results of the viscosity demonstrate that the sweeteners does not interfere with the development of the viscous behavior of the mass being attributed to the use of xanthan gum was unable to maintain the function of the sugar cakes, contributing to a low volume and formation of holes in the internal structure of cakes. Further study on the stability of the air cells in solutions of gum and / or with other bulking agents such as emulsifiers is suggested.
O desenvolvimento de bolos com reduzido teor de aÃÃcar visa atingir o mercado de pessoas com restriÃÃo ao aÃÃcar, ou que optam por produtos mais saudÃveis no entanto, o aÃÃcar nÃo exerce apenas a doÃura caracterÃstica, mas tambÃm controla os principais fenÃmenos responsÃveis pela formaÃÃo estrutural dos bolos, portanto sua reduÃÃo causa prejuÃzos a estrutura dos bolos. Objetivou-se investigar as possÃveis causas da deformaÃÃo interna (formaÃÃo de buracos) em bolos tipo esponja com reduzido teor calÃrico. Para tanto desenvolveram-se sete formulaÃÃes com substituiÃÃes crescentes do aÃÃcar por soluÃÃes adoÃantes (sucralose/ acessulfame K) e goma xantana. Foram produzidos sem farinha de trigo farinha que foi substituÃda integralmente por glÃten em pÃ para verificar se apenas o amido contribui para as deformaÃÃes apresentadas. Depois foram produzidos bolos usando a farinha de trigo, objetivando avaliar os efeitos da substituiÃÃo do aÃÃcar pelas soluÃÃes dos adoÃantes com goma xantana sobre as propriedades tÃrmicas de gelatinizaÃÃo do amido e viscosidade aparente da massa dos bolos. Os resultados dos bolos sem farinha de trigo, demonstraram que a substituiÃÃo do aÃÃcar pelas soluÃÃes dos adoÃantes e da goma xantana, interferiram negativamente nas funÃÃes das proteÃnas, descartando a possibilidade do amido ser o Ãnico agente a contribuir com as deformaÃÃes observadas. Os resultados dos bolos produzidos com farinha de trigo revelaram que o uso dos adoÃantes e goma xantana como substituto do aÃÃcar apresentaram uma capacidade superior ao aÃÃcar e o amido de ligar-se a Ãgua do sistema, elevando as temperaturas (To e Tp) e entalpias de gelatinizaÃÃo resultando no decrÃscimo do grau de gelatinizaÃÃo e o surgimento de zonas escuras, que parece ter sido ocasionado pelo acumulo de compostos da reaÃÃo de maillard. Os resultados referentes a viscosidade demostram que os adoÃantes nÃo interferem no desenvolvimento do comportamento viscoso da massa, sendo atribuÃdo ao uso da goma xantana que nÃo conseguiu suprir a ausÃncia funcional do aÃÃcar nos bolos, contribuindo para o baixo volume e formaÃÃo dos buracos na estrutura interna dos bolos. Sugere-se um estudo mais aprofundado sobre a estabilidade das cÃlulas de ar em soluÃÃes de goma e/ ou associados a outros agentes de volume como os emulsificantes.

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24

Sendek, Callie. "Using Structural Analysis to Assess Possible Formation Mechanisms of the Gneiss Domes of the Harvey Cardiff Domain, Eastern Ontario." Scholarship @ Claremont, 2012. http://scholarship.claremont.edu/scripps_theses/84.

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Gneiss domes are structural features associated with orogens worldwide. This study provides a structural analysis of the domes of the Harvey Cardiff Domain, associated with the Grenville Orogeny. Structural data and oriented samples were collected during field work in the summer of 2012. These were used in combination with published and unpublished foliation and lineation data to analyze structural patterns and determine a mechanism of formation for the domes. The end member scenarios for dome formation were taken from the gneiss dome classification scheme devised by Yin (2004). Most of these mechanisms were eliminated based on a lack of necessary large scale geologic features in the region of the study area. An analysis of the foliation pattern of the Cheddar and Cardiff domes was most consistent with formation by diapirism. However, the foliation patterns of the domes differ from the expected diapiric pattern, and seems to represent a non-horizontal slice through a diapir, cutting through a diapir neck in the north and a diapir hat in the south. This pattern can also be explained by rotation of diapiric foliation due to strain induced by the main orogenic event. This hypothesis was tested using COMSOL, a finite elastic strain model, and found to be realistic. With the methods used in this study it is not possible to tell whether this rotation occurred after or during dome emplacement.

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25

Haddad, Yara. "Investigation of the formation mechanisms of the High Burnup Structure in the spent nuclear fuel - Experimental simulation with ions beams." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS519/document.

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L’objectif de cette thèse est d’étudier et de reproduire les caractéristiques spécifiques de la microstructure du combustible nucléaire irradié à fort taux de combustion, appelée structure HBS (High Burnup Structure). Il s’agit d’étudier les différents paramètres pertinents impliqués dans la formation d’une telle structure, en évaluant leur importance, et en clarifiant leurs éventuelles synergies. Cet objectif a été réalisé en utilisant un système de modèle ultra simplifié, à savoir des monocristaux de dioxyde d’uranium (UO₂) irradiés par des ions de basse énergie (quelques centaines de keV) de Lanthane (La) ou de xénon (Xe) à une température de 773 K, correspondant à celle de la périphérie des véritables pastilles de combustible en réacteur. Les énergies et les masses des ions ont été choisies pour étudier la déstabilisation du solide en fonction de deux paramètres-clefs: (i) les collisions nucléaires élastiques et (ii) la contribution chimique de l'incorporation d'impuretés à forte concentration. Les deux espèces ont été choisies délibérément pour leurs solubilités très différentes dans le dioxyde d’uranium: les ions La sont solubles dans l'UO₂ jusqu’à de très fortes concentrations, tandis que les ions Xe sont insolubles. Les techniques de la Microscopie Électronique en Transmission (TEM) et de Spectrométrie de Rétrodiffusion Rutherford en canalisation RBS/C ont été conduites in situ couplée avec l’irradiation. Ces deux techniques utilisées pour visualiser, quantifier et fournir des informations concernant la fraction des défauts induits par l’irradiation et la formation des bulles, de cavités ou de précipités dans le solide. Les données de canalisation ont été analysées par simulation Monte-Carlo en supposant l’existence de deux catégories de défauts : (i) des atomes aléatoirement déplacés (RDA) et (ii) des distorsions des rangés atomiques (BC). L’évolution de la fraction de défaut de type RDA montre une forte augmentation entre 0.4 à 4.0 dpa (correspondant à une très faible concentration des ions implantés), indépendamment de la nature des ions. Elle est suivie par une saturation de la fraction de RDA pour les deux ions sur une large gamme d’irradiation quoi s’étend jusque 100 dpa. Une forte élévation de la fraction de RDA est observée en particulier pour les cristaux implantés avec des ions Xe pour une concentration élevée dépassant les 4%. En ce qui concerne l’évolution de BC, elle augmente fortement jusqu’à 4 dpa et sature ensuite deux ions La et Xe. Les résultats de microscopie électronique in situ montrent que des défauts identiques pour les deux ions induits par l’irradiation apparaissent, et présentent la même évolution en fonction de la fluence. Les différents défauts évoluent en fonction de la fluence : la première étape correspond à la formation de ‘black dots’ ; la deuxième étape est caractérisée par la formation de boucles puis de lignes de dislocations, qui évoluent finalement jusqu’à commencer à devenir moins différenciables; le processus de restructuration se poursuit et forme un réseau de dislocations enchevêtrées. Une forte densité de bulles de gaz, de taille nanométrique et avec un diamètre moyen de 2 nm est observée pour le cristal Xe implanté à une dose seuil de 4 dpa. Le couplage des deux techniques conduites in situ montre que la différence entre les valeurs à saturation des fractions RDA des deux ions, d’une part, et l'augmentation drastique de RDA à très forte concentration d'ions Xe implantés d’autre part peuvent être attribuées à : (i) la solubilité des ions La vis-à-vis des ions Xe, conduisant à la formation des bulles de gaz de taille nanométrique et (ii) la taille des espèces implantées dans la matrice UO₂, pour laquelle les atomes Xe insolubles ont un rayon atomique beaucoup plus grand que le rayon cationique des atomes U⁴⁺(les atomes La³⁺ ont un rayon atomique similaire à celui des atomes U⁴⁺), responsable de plus de contraintes supplémentaires dans la structure cristalline
The aim of this thesis is to investigate and reproduce the specific features of the microstructure of the high burnup structure of the irradiated nuclear fuel and to explore the various relevant parameters involved in the formation of such a structure, in evaluating their importance, and in clarifying the synergies between them. This have been performed by using a very simplified model system – namely uranium dioxide single crystals- irradiated with low energy La and Xe ions at 773 K, corresponding to the temperature at the periphery of the genuine fuel. The energies and masses of bombarding ions were chosen to investigate the destabilization of the solid due to: (i) the elastic nuclear collisions and by (ii) the chemical contribution of implanting impurities at high concentrations by implanting different ions in UO₂, namely Xe and La, having very different solubility: La species are soluble in UO₂ while Xe ions are insoluble. In situ Transmission electron Microscopy (TEM) and in situ Rutherford Backscattering Spectrometry in the channeling mode (RBS/C), both techniques coupled to ion irradiation, were performed to visualize, quantify and provide information with respect to the fraction of radiation-induced defects and the formation of bubbles, cavities, or precipitates. The channeling data were analyzed afterwards by Monte Carlo simulations assuming two class of defects comprising (i) randomly displaced atoms (RDA) and (ii) bent channels (BC) defects. Regarding the RDA evolution, a sharp increase step appears from 0.4 to 4.0 dpa (corresponding to a low concentration of implanted ions) regardless of nature of ions followed by a saturation of the fraction of RDA for both ions over a wide range of irradiation. A sharp increase of RDA fraction is observed specifically for crystals implanted with Xe ions at a high concentration exceeding 1.5 % (corresponding to the dose of more than 125 dpa). Regarding the BC evolution, for both ions, the evolution shows an increase in the fraction of BC up to 4.0 dpa then the fraction of BC almost saturates for Xe and La ions. In situ TEM results show that a similar radiation-induced defects appear for both ions and the same evolution of defects as a function of the fluence is observed. The various defects evolved as a function of the fluence: starting from the black dot defects formation that were observed as a first type of defects created, then dislocation lines and loops appeared and evolved until they started to be become less distinguishable, the restructuring process continued by forming a tangled dislocation network. A high density of nanometer-sized gas bubbles with a mean diameter 2 nm were observed at room temperature for the Xe-implanted crystal at a threshold dose of 4 dpa. The coupling between both techniques (in situ RBS/C and TEM) demonstrates that the difference between the two plateaus of saturation between the two ions and the dramatic increase of RDA at high concentration of implanted Xe ions can be ascribed to: (i) the solubility of La compared to Xe ions leading to the formation of nanometer-sized gas bubbles and (ii) the size of implanted species in UO₂ matrix where insoluble Xe atoms have an atomic radius much larger than the cationic radius of U⁴⁺ atoms, (La³⁺ atoms have a similar atomic radius as U⁴⁺ atoms) responsible for more stress in UO₂ crystal

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26

Bohli, Nadra. "Etude physique de la formation de films à base de polymères conducteurs et applications en micro-éléctronique." Thesis, Bordeaux 1, 2009. http://www.theses.fr/2009BOR13961/document.

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La polyaniline est un polymère conducteur intrinsèque aux potentialités indéniables dans le domaine de la micro-électronique. Elle allie la légèreté, le faible coût et la modularité des polymères avec les propriétés de conduction électrique des métaux. La mise à profit de ce mélange de propriétés à l’échelle industrielle nécessite une maitrise des procédés de mise en œuvre de la polyaniline, notamment sous forme de film polymère, domaine où il y a encore un manque de maitrise. Pour y remédier, il faudrait tout d’abord comprendre l’influence de chaque paramètre de mise en œuvre sur les propriétés de conduction du film de polyaniline. Pour cela, nous avons choisi une polyaniline plast-dopée commerciale à l’état de dispersion et avons fait une étude paramétrique sur l’effet du type de solvant utilisé pour la dispersion ainsi que celui de la température d’évaporation de celui-ci lors du dépôt du film. Deux types d’études ont été menés : la première porte sur les propriétés rhéologiques et diélectriques des dispersions de polyaniline et la seconde sur les propriétés structurales et de conduction des films. A travers la première étude, nous avons pu montré que lors du chauffage des dispersions de polyaniline, celles-ci subissaient une transition structurale liquide-liquide du second ordre dont les paramètres varient avec le type du solvant utilisé. A travers la seconde étude, nous avons aussi mis en évidence que les films déposés dans les domaines avoisinant la température transition de phase dans les mélanges liquides sont les moins conducteurs et les moins cristallisés. Selon le type de solvant choisi, deux mécanismes de conduction ont été trouvés : les sauts à portées variables tridimensionnel (VRH 3D), pour le cas de la série de films issus de la dispersion dans l’acide dichloroacétique et déplacement par effet tunnel induit par les fluctuations thermiques (FIT) pour la série de films issus de la dispersion dans le mélange acide dichloroacétique / acide formique. Il en ressort finalement que pour obtenir un film de polyaniline plast-dopée ayant la conductivité la plus élevée, il faut appliquer les conditions expérimentales qui permettent d’obtenir un degré de cristallinité élevé (298 K pour PANI/DCAA)
The purpose of this study is to perform polyaniline films with the highest conductivity. The effect of the solvent type and the casting temperature on the electrical properties of plastdoped polyaniline dispersions and films were investigated. For this purpose, rheological and dielectric investigations have been undertaken for dispersions of plast-doped polyaniline in two different solvents (dichloroacetic acid and formic acid / dichloroacetic acid mixture). Changes appearing above a certain temperature, 318K for PANI/DCAA and 313K for PANI/DCAA-FA, for both rheological dielectric and rheological parameters revealed the existence of a second order liquid-liquid structural transition occurring in the polyaniline organic dispersions. We also investigated the effect of the selected processing parameters on the film properties. We found that the DC conductivity mechanism is governed by Mott’s three-dimensional variable range hopping (3D VRH) model for PANI/DCAA films and by a fluctuation induced tunnelling model (FIT) for PANI/DCAA-FA films. Besides, the films cast at temperatures around the second order liquid-liquid structural transition temperature of polyaniline dispersions lead to the lowest conductivity and crystallinity, regardless of the solvent type used. A qualitative correlation was also found between the conductivity and the crystallinity of the polyaniline films. So, in order to obtain films with the highest electric conductivities, we have to apply experimental conditions leading to the highest crystallinity (298 K for PANI/DCAA)

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27

Woodman, Michael. "Formation de motif dynamique et structuré dans les circuits neuronaux et des réseaux du cerveau à grande échelle." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4022/document.

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Un des challenges en neurosciences consiste à trouver une bonne adéquation entre le comportement et l'activité neuronale stimulée, le but à long terme étant d'obtenir un modèle prédictif. Les travaux ré- cents dans le domaine comportemental ont montré la mise en place d'outils d'analyses comme ceux utilisés en physique non linéaire, qui permettent une meilleure comparaison avec les modèles neu- ronaux. Nous montrons dans cette thèse que les processus neuraux et comportementales peuvent être visualisés sous forme de motifs, voire de structures dans un sous espace à multiple degrés de liberté, sous forme de trajectoires dans l'espace des phases afin de montrer la dynamique non linéaire émergeante. Nous présentons aussi deux exemples , l'un est le taux de pics d'activité et leur comportement temporel qui permet de générer une base des états dynamiques de l'ensemble du cerveau, l'autre montre comment identifier les mo- tifs ou sous réseaux actifs en présence de synchronisation à longue distance. Ces travaux montrent comment modéliser l'activité cor- ticocorticale afin de contribuer à l'état de référence du cerveau. A partir de l'activité neuronale simulée nous sommes donc en mesure d'identifier les motifs et sous réseaux mis en jeu et prévoir l'activité à court terme qui peut être observée ainsi que leurs implications futurs
A persistent question in the neurosciences asks what aspects of behavior correspond to neural activity. This means finding predictors of behavioral state from neural state, yet behavioral studies have shown that behaviors are structured state and time and may be described mathematically by nonlinear dynamical systems. Another similarity found between behavior and neurosciences is the coordination of many degrees of freedom. Given these two similarities, this thesis suggests that neural and behavioral processes involve 1) the task specific formation of patterns that bind or coordinate degrees of freedom such that only a few degrees of freedom remain and 2) the structured, nonlinear dynamical interaction of these degrees of freedom, tracing out trajectories in state space that may correspond to the completion of a task or recognition of visual stimulus. The combination of these two complementary aspects will be referred to structured flows on manifolds. This thesis provides two examples of how such structure can be found in neural network models both at the level of spiking neural circuits, as well as large-scale inter-regional networks in a whole brain model. We discuss the two contributions in terms of the common principles of pattern formation and structured nonlinear dynamical interactions and how these principles allow for a link to made between the dynamics of behaviors and dynamics of underlying neural networks, and in conclusion, we outline experimental predictions and future work motivated by this thesis

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28

YOSHIDA, Takeshi, and S. M. P. SAMARAKOON. "Symbiotic Commitment and the Process of New Organizational Forms: Mechanism of Chaotic Behaviour and the Structural Formation in Organizations." 名古屋大学経済学会, 2007. http://hdl.handle.net/2237/10491.

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29

Thiesset, Fabien. "Exploration analytique et expérimentale des interactions cohérence-turbulence au sein d'un écoulement de sillage." Phd thesis, Université de Rouen, 2011. http://tel.archives-ouvertes.fr/tel-00880987.

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Depuis les travaux de Townsend (1956), il est désormais largement admis qu'un mouvement organisé persiste dans la majorité écoulements cisaillés. Suivant la proposition de Townsend, Reynolds & Hussain (1972) apportent la première démarche analytique en développant, entre autres, les bilans énergétiques en "un point" du mouvement organisé et aléatoire. Cependant, un minimum de deux points est nécessaire afin de définir une échelle et décrire les processus énergétiques à chaque échelle. Pour cette raison, les équations de transport des statistiques en deux points furent initialement considérées par Taylor, Kármán & Howarth, Kolmogorov ou Yaglom. Ces derniers postulent que pour des Reynolds infinis, il existe une échelle où l'influence des structures cohérentes disparaît. Or, les nombres de Reynolds rencontrés en laboratoire ne sont pas suffisamment grands pour qu'une telle supposition soit avérée. La contribution énergétique du mouvement cohérent doit alors être dissociée du reste du champ fluctuant. Le premier objectif de cette thèse est d'affiner les théories existantes en proposant les bilans énergétiques en "deux points" prenant en considération le mouvement cohérent. Puis, à partir de diverses méthodes expérimentales mises en place au CORIA et de données issues d'une collaboration avec l'Université de Newcastle (Australie), l'écoulement de sillage est exploré. Les théories statistiques sont alors utilisées comme outil, afin de décrire l'écoulement avec un degré de complexité croissant. Les attentions se portent sur les interactions cohérence - turbulence, en termes de transport, de contribution énergétique ou de transfert d'énergie au sein de la cascade.

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30

Allen, Robert Michael. "A study of the processes involved in the formation of nano-structures inorganic materials, using high brightness electron beams." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240887.

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31

Cheng, Zhe. "Reaction Kinetics and Structural Evolution for the Formation of Nanocrystalline Silicon Carbide via Carbothermal Reduction." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5896.

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Nanocrystalline beta-silicon carbide (ß-SiC) was synthesized at relatively low temperature (<1300C) by carbothermal reduction (CTR) reaction in fine scale carbon/silica mixtures. The fine scale mixing of the reactants (i.e., carbon and silica) was achieved by solution-based processing and subsequent heat treatment. The mechanism of the CTR reaction in the current system was investigated from different aspects. The condensates of the volatile species generated during the CTR reaction was collected and analyzed. The results supported previous investigations which suggested that the CTR reaction is a multi-step process that involves silicon monoxide (SiO) vapor as a reaction intermediate. The kinetics of the CTR reaction was investigated by isothermal weight loss study and by the study which determined the amount of SiC formed via quantitative X- ray diffraction (QXRD) analysis. The results of kinetic study were consistent with the "shrinking-core" model, in which the reaction between SiO vapor and carbon at the carbon surface to produce SiC is the rate-controlling step. In addition, several techniques, including XRD, gas adsorption analysis, laser diffraction particle size analysis, SEM, TEM, etc., had been used to study the structural evolutions of the reaction product of CTR. It was demonstrated that the evolutions of product structure characteristics such as crystallite size, specific surface area, specific pore volume, pore size distribution, particle size distribution, and powder morphology, etc. were consistent with each other and provided support to the reaction mechanism proposed.

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32

Nagy, Péter. "Formation and Decomposition of Platinum–Thallium Bond, Kinetics and Mechanism. Structural Characterization of Some Metal Cyanides in the Solid State." Doctoral thesis, KTH, Chemistry, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3803.

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The kinetic and mechanistic features of a new series ofplatinum-thallium cyano compounds containing a direct andunsupported by ligands metal-metal bond have been studied insolution, using standard mixandmeasurespectrophotometric technique and stoppedflow method.These reactions are interpreted as oxidative addition of the cspecies to the square planar Pt(CN)₄^2-complex. Each of these processes was found to befirst-order in Pt(CN)₄^2-, the corresponding TI^IIIcomplex and a cyanide ion donating species whichacts as a catalyst. Both di- and trinuclear complexes werestudied, and the kinetically significant thallium complexes intheir formation and the catalytically active cyanide sourcesare as follows: [(CN)₅PtTl(CN)₃]^3-: Tl(CN)₄(alkaline region), Tl(CN)₃(slightly acidic region) and CN; [(CN)₅PtTl(CN)]: Tl(CN)₂⁺and Tl(CN)₂⁺; [(CN)₅PtTlPt(CN)₅]^3-: [(CN)₅PtTl(CN)]and HCN. Appropriatemechanisms were postulated for the overall reactions in allcases, which include i) metalmetal bond formation stepand ii) coordination of an axial cyanide ion to the platinumcenter. Two experimentally indistinguishable kinetic modelswere proposed for the formation of the dinuclear complexeswhich are different in the sequence of the two steps. In thecase of the trinuclear complex, experimental evidence isavailable to exclude one of the alternative reaction paths, andit was proven that the metalmetal bond formation precedesthe axial cyanide coordination.

The cyanide ligands coordinated to TI^IIIin the PtTl complexes could be replacedsuccessfully with aminopolycarboxylates e.g.: mimda^2-, nta^3-, edta^4-. The [(CN)₅PtTl(edta)]^4-complex, with a direct metalmetal bond hasbeen prepared in solution by two different reactions: a)dissolution of [(CN)₅PtTl](s) in an aqueous solution of edta, b)directly from Pt(CN)₄^2-and Tl(edta)(CN)^2-. The decomposition reaction is greatlyaccelerated by cyanide and significantly inhibited by edta. Itproceeds through the [(CN)₅PtTl(CN)₃]^3-intermediate. The formation of [(CN)₅PtTl(edta)]^4-can proceed via two different pathways dependingon the ratio of the cyanide to the edta ligand concentrations.Thedirect pathat excess of edta means theformation of intermediate[(CN)4Pt···Tl(CN)(edta)]^4-, followed by a release of the cyanide from theTlcentre followed by coordination of a cyanide from thebulk to the Ptcentre of the intermediate. Theindirect pathdominates in the absence of extraedta and the formation of the PtTl bond occours betweenPt(CN)₄^2-and Tl(CN)4.

Homoligand MTl(CN)₄(M = Tl^I, K, Na) and, for the first time, Tl(CN)₃species have been synthesized in the solid stateand their structures solved by single crystal Xraydiffraction method. Interesting redox processes have been foundbetween TI^IIIand CNin nonaqueous solution and in Tl₂O₃-CNaqueous suspension. In the crystal structureof Tl(CN)₃·H₂O, the thallium(III) ion has a trigonal bypiramidalcoordination geometry with three cyanides in the trigonalplane, while an oxygen atom of the water molecule and anitrogen atom from a cyanide ligand attached to a neighboringthallium complex, form a linear OTlN fragment.Cyanide ligand bridges thallium units forming an infinitezigzag chain structure. Among the thallium(III) tetracyanocompounds, the isostructural M[Tl(CN)₄](M = Tl and K) and Na[Tl(CN)₄]·3H₂O crystallize in different crystal systems, but thethallium(III) ion has in all cases the same tetrahedralgeometry in the [Tl(CN)₄]unit.

Three adducts of mercury(II) (isoelectronic with TI^III) (K₂PtHg(CN)₆·2H₂O, Na₂PdHg(CN)₆·2H₂O and K₂NiHg(CN)₆·2H₂O) have been prepared from Hg(CN)₂and square planar transition metal cyanides M^II(CN)₄^2-and their structure have been studied by singlecrystal Xray diffraction, XPS and Raman spectroscopy inthe solid state. The structure of (K₂PtHg(CN)₆·2H₂O consists of strictly linear one dimensional wireswith Pt^IIand Hg^IIcenters located alternately, d_HgPt= 3.460 Å. The structure of Na₂PdHg(CN)₆·2H₂O and K₂NiHg(CN)₆·2H₂O can be considered as double salts, the lack ofheterometallophilic interaction between both the Hg^IIand Pd^IIatoms, d_HgPd= 4.92 Å, and Hg^IIand Ni^IIatoms, d_NiPd= 4.60 Å, seems obvious. Electronbinding energy values of the metallic centers measured by XPSshow that there is no electron transfer between the metal ionsin all three adducts. In solution, experimental findingsclearly indicate the lack of metalmetal bond formation inall studied Hg^IICN^-M^II(CN)4^2-systems (M = Pt, Pd and Ni). It is in contrary tothe platinumthallium bonded cyanides.

KEYWORDS:metalmetal bond, platinum, thallium,kinetics, mechanism, stopped flow, oxidative addition, cyanocomplexes, edta, redox reaction, metal cyanides, Xraydiffraction, Raman, NMR, mercury, palladium, nickel, onedimensional wire

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33

Dick, Veronika V. [Verfasser], Andrey V. [Akademischer Betreuer] Solov'yov, and Stefan [Akademischer Betreuer] Schramm. "Mechanisms of nanofractal structure formation and post-growth evolution / Veronika V. Dick. Gutachter: Andrey V. Solov'yov ; Stefan Schramm. Betreuer: Andrey V. Solov'yov." Frankfurt am Main : Univ.-Bibliothek Frankfurt am Main, 2011. http://d-nb.info/1045004715/34.

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34

Siebert, Julien. "Statistical mechanics of the self-gravitating gases." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2005. http://tel.archives-ouvertes.fr/hal-00009142.

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The self-gravitating systems are formed by particles interacting through gravity. They describe structure formation in the universe. As a consequence of the long range interaction of gravity, they are inhomogeneous even at thermal equilibrium. We study the self-gravitating systems with several kinds of particles and the self-gravitating systems in the presence of the cosmological constant $ Lambda$. We formulate the statistical mechanics and the mean field approach describing the gaseous phase. We explicitely compute the density of particles and thermodynamic quantities. The presence of $ Lambda$ extends the domain of stability of the gaseous phase. Monte Carlo simulations show that the mean field describes the gaseous phase with an excellent accuracy. Scalling law of the self-gravitating systems with several kinds of particles is found. At the critical point the fractal dimension is independant of their composition and is $1.6...$~.

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35

Salem, Essa KH I. J. "NUMERICAL SIMULATIONS OF PREMIXED FLAMES OF MULTI COMPONENT FUELS/AIR MIXTURES AND THEIR APPLICATIONS." UKnowledge, 2019. https://uknowledge.uky.edu/me_etds/132.

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Combustion has been used for a long time as a means of energy extraction. However, in the recent years there has been further increase in air pollution, through pollutants such as nitrogen oxides, acid rain etc. To solve this problem, there is a need to reduce carbon and nitrogen oxides through lean burning, fuel dilution and usage of bi-product fuel gases. A numerical analysis has been carried out to investigate the effectiveness of several reduced mechanisms, in terms of computational time and accuracy. The cases were tested for the combustion of hydrocarbons diluted with hydrogen, syngas, and bi-product fuel in a cylindrical combustor. The simulations were carried out using the ANSYS Fluent 19.1. By solving the conservations equations, several global reduced mechanisms (2-5-10 steps) were obtained. The reduced mechanisms were used in the simulations for a 2D cylindrical tube with dimensions of 40 cm in length and 2.0 cm diameter. The mesh of the model included a proper fine quad mesh, within the first 7 cm of the tube and around the walls. By developing a proper boundary layer, several simulations were performed on hydrocarbon/air and syngas blends to visualize the flame characteristics. To validate the results “PREMIX and CHEMKIN” codes were used to calculate 1D premixed flame based on the temperature, composition of burned and unburned gas mixtures. Numerical calculations were carried for several hydrocarbons by changing the equivalence ratios (lean to rich) and adding small amounts of hydrogen into the fuel blends. The changes in temperature, radical formation, burning velocities and the reduction in NOx and CO2 emissions were observed. The results compared to experimental data to study the changes. Once the results were within acceptable range, different fuels compositions were used for the premixed combustion through adding H2/CO/CO2 by volume and changing the equivalence ratios and preheat temperatures, in the fuel blends. The results on flame temperature, shape, burning velocity and concentrations of radicals and emissions were observed. The flame speed was calculated by finding the surface area of the flame, through the mass fractions of fuel components and products conversions that were simulated through the tube. The area method was applied to determine the flame speed. It was determined that the reduced mechanisms provided results within an acceptable range. The variation of the inlet velocity had neglectable effects on the burning velocity. The highest temperatures were obtained in lean conditions (0.5-0.9) equivalence ratio and highest flame speed was obtained for Blast Furnace Gas (BFG) at elevated preheat temperature and methane-hydrogen fuels blends in the combustor. The results included; reduction in CO2 and NOx emissions, expansion of the flammable limit, under the condition of having the same laminar flow. The usage of diluted natural gases, syngas and bi-product gases provides a step in solving environmental problems and providing efficient energy.

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36

De, Villiers Katherine A. "Structural characterisation of ferrihaem in solution : insights into the mechanism of formation of malaria pigment and its inhibition by aryl methanol antimalarial drugs." Doctoral thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/6301.

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37

Hichri, Bassem. "Design and control of collaborative, cross and carry mobile robots : C3Bots." Thesis, Clermont-Ferrand 2, 2015. http://www.theses.fr/2015CLF22601/document.

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L'objectif du travail proposé est de concevoir et commander un groupe des robots mobiles similaires et d'architecture simple appelés m-bots (mono-robots). Plusieurs m-bots ont la capacité de saisir ensemble un objet afin d'assurer sa co-manipulation et son transport quelle que soit sa forme et sa masse. Le robot résultant est appelé p-bot (poly-robot) et est capable d'effectuer des tâches de déménageur pour le transport d'objets génériques. La reconfigurabilité du p-bot par l'ajustement du nombre des m-bots utilisés permet de manipuler des objets lourds et des objets de formes quelconques (particulièrement s'ils sont plus larges qu'un seul m-bot). Sont considérés dans ce travail l'évitement d'obstacle ainsi que la stabilité du p-bot incluant la charge à transporter. Une cinématique pour un mécanisme de manipulation a été proposée et étudiée. Ce dernier assure le levage de la charge et son dépôt sur le corps des robots pour la transporter. Plusieurs variantes d'actionnement ont été étudiées : passif, avec compliance et actionné. Un algorithme de positionnement optimal des m-bots autour de l'objet à manipuler a été proposé afin d'assurer la réussite de la tâche à effectuer par les robots. Cet algorithme respecte le critère de "Force Closure Grasping" qui assure la stabilité de la charge durant la phase de manipulation. Il maintient aussi une marge de stabilité statique qui assure la stabilité de l'objet durant la phase de transport. Enfin, l'algorithme respecte le critère des zones inaccessibles qui ne peuvent pas être atteintes par les m-bots. Une loi de commande a été utilisée afin d'atteindre les positions désirées pour les m-bots et d'assurer la navigation en formation, durant la phase du transport, durant laquelle chaque robot élémentaire doit maintenir une position désirée par rapport à l'objet transporté. Des résultats de simulation pour un objet de forme quelconque, décrite par une courbe paramétrique, sont présentés. Des simulations 3D en dynamique multi-corps ainsi que des expériences menées sur les prototypes réalisés ont permis de valider nos propositions
Our goal in the proposed work is to design and control a group of similar mobile robots with a simple architecture, called m-bot. Several m-bots can grip a payload, in order to co-manipulate and transport it, whatever its shape and mass. The resulting robot is called a p-bot andis capable to solve the so-called "removal-man task" to transport a payload. Reconfiguring the p-bot by adjusting the number of m-bots allows to manipulate heavy objects and to manage objects with anyshape, particularly if they are larger than a single m-bot. Obstacle avoidance is addressed and mechanical stability of the p-bot and its payload is permanently guaranteed. A proposed kinematic architecture for a manipulation mechanism is studied. This mechanism allows to lift a payload and put it on them-bot body in order to be transported. The mobile platform has a free steering motion allowing the system maneuver in any direction. An optimal positioning of the m-bots around the payload ensures a successful task achievement without loss of stability for the overall system. The positioning algorithm respects the Force Closure Grasping (FCG) criterion which ensures the payload stability during the manipulation phase. It respects also the Static Stability Margin (SSM) criterion which guarantees the payload stability during the transport. Finally, it considers also the Restricted Areas (RA) that could not be reached by the robots to grab the payload. A predefined control law is then used to ensure the Target Reaching (TR) phase of each m-bot to its desired position around the payload and to track a Virtual Structure (VS), during the transportation phase, in which each elementary robot has to keep the desired position relative to the payload. Simulation results for an object of any shape, described by aparametric curve, are presented. Additional 3D simulation results with a multi-body dynamic software and experiments by manufactured prototypes validate our proposal

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38

Zhang, Gongwang. "THE FORMATION MECHANISM OF α-PHASE DISPERSOIDS AND QUANTIFICATION OF FATIGUE CRACK INITIATION BY EXPERIMENTS AND THEORETICAL MODELING IN MODIFIED AA6061 (AL-MG-SI-CU) ALLOYS". UKnowledge, 2018. https://uknowledge.uky.edu/cme_etds/90.

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AA6061 Al alloys modified with addition of Mn, Cr and Cu were homogenized at temperatures between 350 ºC and 550 ºC after casting. STEM experiments revealed that the formation of α-Al(MnFeCr)Si dispersoids during homogenization were strongly affected by various factors such as heating rate, concentration of Mn, low temperature pre-nucleation treatment and homogenization temperature. Through analysis of the STEM results using an image software Image-Pro, the size distributions and number densities of the dispersoids formed during different annealing treatments were quantitatively measured. It was revealed that increasing the heating rate or homogenization temperature led to a reduction of the number density and an increase in size of the dispersoids. The number density of dispersoids could be markedly increased through a low temperature pre-nucleation treatment. A higher Mn level resulted in the larger number density, equivalent size and length/width ratio of the dispersoids in the alloy. Upsetting tests on two of these Mn and Cr-containing AA6061 (Al-Mg-Si-Cu) Al alloys with distinctive Mn contents were carried out at a speed of 15 mm s-1 under upsetting temperature of 450 ºC after casting and subsequent homogenization heat treatment using a 300-Tone hydraulic press. STEM experiments revealed that the finely distributed α-Al(MnFeCr)Si dispersoids formed during homogenization showed a strong pinning effect on dislocations and grain boundaries, which could effectively inhibit recovery and recrystallization during hot deformation in the two alloys. The fractions of recrystallization after hot deformation and following solution heat treatment were measured in the two alloys with EBSD. It was found that the recrystallization fractions of the two alloys were less than 30%. This implied that the finely distributed α-dispersoids were rather stable against coarsening and they stabilized the microstructure by inhibiting recovery and recrystallization by pinning dislocations during deformation and annealing at elevated temperatures. By increasing the content of Mn, the effect of retardation on recrystallization were further enhanced due to the formation of higher number density of the dispersoids. STEM and 3-D atom probe tomography experiments revealed that α-Al(MnFeCr)Si dispersoids were formed upon dissolution of lathe-shaped Q-AlMgSiCu phase during homogenization of the modified AA6061 Al alloy. It was, for the first time, observed that Mn segregated at the Q-phase/matrix interfaces in Mn-rich regions in the early stage of homogenization, triggering the transformation of Q-phase into strings of Mn-rich dispersoids afterwards. Meanwhile, in Mn-depleted regions the Q-phase remained unchanged without segregation of Mn at the Q-phase/matrix interfaces. Upon completion of α-phase transformation, the atomic ratio of Mn and Si was found to be 1:1 in the α-phase. The strengthening mechanisms in the alloy were also quantitatively interpreted, based on the measurements of chemical compositions, dispersoids density and size, alloy hardness and resistivity as a function of the annealing temperature. This study clarified the previous confusion about the formation mechanism of α-dispersoids in 6xxx series Al alloys. Four-point bend fatigue tests on two modified AA6061 Al alloys with different Si contents (0.80 and 1.24 wt%, respectively) were carried out at room temperature, f = 20 Hz, R = 0.1, and in ambient air. The stress-number of cycles to failure (S-N) curves of the two alloys were characterized. The alloys were solution heat treated, quenched in water, and peak aged. Optical microscopy and scanning electron microscopy were employed to capture a detailed view of the fatigue crack initiation behaviors of the alloys. Fatigue limits of the two alloys with the Si contents of 0.80 and 1.24 wt% were measured to be approximately 224 and 283.5 MPa, respectively. The number of cracks found on surface was very small (1~3) and barely increased with the applied stress, when the applied stress was below the yield strength. However, it was increased sharply with increase of the applied stress to approximately the ultimate tensile strength. Fatigue crack initiation was predominantly associated with the micro-pores in the alloys. SEM examination of the fracture surfaces of the fatigued samples showed that the crack initiation pores were always aspheric in shape with the larger dimension in depth from the sample surface. These tunnel-shaped pores might be formed along grain boundaries during solidification or due to overheating of the Si-containing particles during homogenization. A quantitative model, which took into account the 3-D effects of pores on the local stress/strain fields in surface, was applied to quantification of the fatigue crack population in a modified AA6061 Al alloy under cyclic loading. The pores used in the model were spherical in shape, for simplicity, with the same size of 7 μm in diameter. The total volume fraction of the pores in the model were same as the area fraction of the pores measured experimentally in the alloy. The stress and strain fields around each pore near the randomly selected surface in a reconstructed digital pore structure of the alloy were quantified as a function of pore position in depth from the surface using a 3-D finite element model under different stress levels. A micro-scale Manson-Coffin equation was used to estimate the fatigue crack incubation life at each of the pores in the surface and subsurface. The population of fatigue cracks initiated at an applied cyclic loading could be subsequently quantified. The simulated results were consistent with those experimentally measured, when the applied maximum cyclic stress was below the yield strength, but the model could not capture the sudden increase in crack population at UTS, as observed in the alloy. This discrepancy in crack population was likely to be due to the use of the spherical pores in the model, as these simplified pores could not show the effects of pore shape and their orientations on crack initiation at the pores near surface. Although it is presently very time-consuming to calculate the crack population as a function of pore size and shape in the alloy with the current model, it would still be desirable to incorporate the effects of shape and orientation of the tunnel-shaped pores into the model, in the future, in order to simulate the fatigue crack initiation more accurately in the alloy.

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39

Maio, Giampaolo. "Pollutant prediction in numerical simulations of laminar and turbulent flames using virtual chemistry." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASC003.

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La CFD est aujourd’hui utilisée par les ingénieurs de recherche comme un outil numérique pour concevoir et optimiser les dispositifs de combustion avancés qui sont utilisés dans les systèmes de conversion d’énergie. L’un des principaux objectifs de la recherche, dans le développement d’outils numériques avancés pour la CFD, est l’identification d’un modèle réduite de cinitique chimique de la combustion qui reproduit la structure de la flamme et la formation de polluants avec un coût de calcul abordable. En particulier, la prédiction de la formation de polluants est une tâche difficile lorsque des flammes complexes sont rencontrées: stratification du mélange, pertes de chaleur et recirculation des gaz brûlés. Le travail de recherche mené dans cette these se concentre sur la modélisation de la formation monoxyde de carbone (CO) et des oxydes d’azote (NOx) dans des conditions de flamme complexes en utilisant une methode récemment développée et appelée chimie virtuelle: celle-ci consiste à concevoir des mécanismes réduits constitués d’un réseau d’un nombre optimisé d’espèces virtuelles interagissant via des réactions virtuelles optimisées. Dans une première étape, les mécanismes virtuels sont développés et validés dans des configurations de flammes 1-D. Dans un deuxième temps, ceux-ci sont utilisés pour calculer plusieurs configurations de flammes 2-D laminaires et 3-D turbulentes sur une large gamme de régimes de combustion: prémélangé, non prémélangé, partiellement prémélangé et non adiabatique. Les résultats obtenus sont validés avec des données expérimentales et avec des calculs inclutant une cinetique chimique détaillée
CFD is nowadays used by research engineers as a numerical tool to design and optimize advanced combustion devices that are employed in energy conversion systems. In the development of advanced numerical CFD tools, one of the main research challenges is the identification of a reduced combustion chemistry model able to find a compromise between accurate reproduction of the flame structure and pollutants formation with an affordable CPU cost. In particular, pollutants formation prediction is a difficult task when complex flame environments are encountered: flame characterized by mixture stratification, heat loss and burnt gas recirculation. The present research work focuses on the modeling of CO and NOx formation in complex flame conditions using a reduced finite rate chemistry approach. CO and NOx reduced chemistry models are here developed using the recent virtual chemistry model; it consists in designing reduced mechanisms made of a network of an optimized number of virtual species interacting through virtual optimized reactions. In the first step, the virtual chemistry mechanisms are developed and validated in 1-D flames comparing the results with detailed chemistry. In a second step, they are employed to compute several 2-D laminar and 3-D turbulent flame configurations which include different combustion regimes: premixed, onpremixed, partially-premixed and non-adiabatic conditions. The obtained results are validated either with experimental data or with detailed chemistry computations

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40

Dal-Pra, Sophie. "Etude des mécanismes contrôlant la formation de l’axe dorso-ventral et analyse de l’établissement et du maintien des structures axiales au cours de l’embryogenèse précoce du poisson zèbre (Danio rerio)Study of the mechanisms controling the formation of the dorso-ventral axis and analysis of the establishment and the maintenance of axial structures during early embryogenesis of the zebrafish (Danio rerio)." Université Louis Pasteur (Strasbourg) (1971-2008), 2007. https://publication-theses.unistra.fr/public/theses_doctorat/2007/DAL-PRA_Sophie_2007.pdf.

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Le centre organisateur de Spemann, situé dorsalement, participe à l’établissement de l’axe Dorso-Ventral et se différencie en structures axiales. J’ai étudié ces deux aspects de l’écusson embryonnaire, la structure analogue à l’Organisateur chez le poisson zèbre. La régionalisation DV des embryons résulte en partie de l’interaction entre les BMP, exprimés ventralement,et leurs antagonistes sécrétés dorsalement. J’ai montré que les antagonistes Nog1 et Fstl2 fonctionnent de façon redondante à Chd, un autre antagoniste des BMP, pendant les stades Blastula/Gastrula pour établir un gradient DV de BMP. Ensuite j’ai étudié le rôle des facteurs de transcription de la famille FoxA dans le développement des structures axiales. Ces facteurs sont requis pendant la gastrulation afin de maintenir l’identité des précurseurs de l’axe. Cette activité est partiellement redondante à celle de Flh. En conclusion, l’écusson participe à la formation de l’axe DV et à celle des structures axiales, en utilisant des molécules aux activités redondantes.

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41

Elbagerma, Mohamed A. "Analytical method development for structural studies of pharmaceutical and related materials in solution and solid state : an investigation of the solid forms and mechanisms of formation of cocrystal systems using vibrational spectroscopic and X-ray diffraction techniques." Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/4467.

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Analysis of the molecular speciation of organic compounds in solution is essential for the understanding of ionic complexation. The Raman spectroscopic technique was chosen for this purpose because it allows the identification of compounds in different states and it can give information about the molecular geometry from the analysis of the vibrational spectra. In this research the ionisation steps of relevant pharmaceutical material have been studied by means of potentiometry coupled with Raman spectroscopy; the protonation and deprotonation behaviour of the molecules were studied in different pH regions. The abundance of the different species in the Raman spectra of aqueous salicylic acid, paracetamol, citric acid and salicylaldoxime have been identified, characterised and confirmed by numerical treatment of the observed spectral data using a multiwavelength curve-fitting program. The non-destructive nature of the Raman spectroscopic technique and the success of the application of the multiwavelength curve-fitting program demonstrated in this work have offered a new dimension for the rapid identification and characterisation of pharmaceuticals in solution and have indicated the direction of further research. The work also covers the formation of novel cocrystal systems with pharmaceutically relevant materials. The existence of new cocrystals of salicylic acid-nicotinic acid, DLphenylalanine , 6-hydroxynicotinic acid, and 3,4-dihydroxybenzoic acid with oxalic acid have been identified from stoichiometric mixtures using combined techniques of Raman spectroscopy (dispersive and transmission TRS), X-ray powder diffraction and thermal analysis. Raman spectroscopy has been used to demonstrate a number of important aspects regarding the nature of the molecular interactions in the cocrystal. Cocrystals of salicylic acid - benzamide, citric acid-paracetamol and citric acid -benzamide have been identified with similar analytical approaches and structurally characterised in detail with single crystal X-ray diffraction. From these studies the high selectivity and direct micro sampling of Raman spectroscopy make it possible to identify spectral contributions from each chemical constituent by a peak wavenumber comparison of single-component spectra (API and guest individually) and the two- component sample material (API/guest), thus allowing a direct assessment of cocrystal formation to be made. Correlation of information from Raman spectra have been made to the X-ray diffraction and thermal analysis results. Transmission Raman Spectroscopy has been applied to the study cocrystals for the first time. Identification of new phases of analysis of the low wavenumber Raman bands is demonstrated to be a key advantage of the TRS technique.

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Дехтяр, Надія Анатоліївна, Надежда Анатольевна Дехтярь та Nadiia Anatoliivna Dekhtiar. "Фінансовий механізм функціонування інтегрованих виробничих формувань в умовах ринкової економіки". Thesis, Українська академія банківської справи, 2003. http://essuir.sumdu.edu.ua/handle/123456789/51550.

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У роботі досліджено фінансово-економічні передумови виникнення і розвитку інтеграційних процесів та визначено особливості впливу основних мотиваційних чинників на характер інтеграційних зв’язків в умовах посилення ринкових відносин. Поглиблено сутність поняття “інтегроване виробниче формування” як об’єднання підприємств, організацій, установ у багатогалузеву господарську систему на основі договірних відносин чи консолідації активів з метою досягнення спільних цілей або забезпечення вирішального впливу на фінансову, господарську і комерційну політику учасників формувань та здійснено класифікацію форм інтегрованих структур за основними ознаками. Конкретизовано специфічні ознаки створення галузевих інтегрованих формувань в Україні у процесі комбінування діяльності підприємств та обґрунтовано схеми фінансового забезпечення їх функціонування. На основі порівняльного аналізу ефективності функціонування інтегрованих виробничих формувань і бізнесгруп в Україні обґрунтовано нові методичні підходи до оцінки ефективності інтеграції на основі розрахунку узагальнюючого комплексного показника, що враховує рівень інтеграційних переваг та внесені пропозиції щодо оцінки ефективності управління за їх діяльністю в умовах перерозподілу прав власності.
The financial and economic premises of origin and development of integrated processes are investigated; the features of influence of the main motivated factors on a character of integrated connections in the market economics are determined in the research. The essence of concept “of integrated industrial formation” as associations of the enterprises, organizations, establishments in a diversified economic system on the basis of contractual attitudes or consolidation of assets with the purpose of reaching general purposes or maintenance of decisive influence on financial, economic and commercial policy of the participants of formations is profound and also the classification of the forms of integrated structures according to main indications is carried out. The specific indications of creation of branch-integrated formations in Ukraine in the process of the combination enterprises’ activity are rendered and the schemes of financial maintenance of their functioning are considered. On the basis of comparative analysis of efficiency of functioning of integrated industrial formations and business-groups in Ukraine the new methodical approaches to an estimation efficiency of integration on the basis of calculation of the generalizing complex index are justified. The offered index considers the level of integrated benefits. Also propositions to estimation of management efficiency by activity in the conditions of redistribution of the property rights are introduced.

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Грод, Андрій Михайлович, Андрей Михайлович Грод та A. Grod. "Формування конкурентоспроможних підприємницьких структур в умовах меблевого виробництва". Thesis, Тернопільський національний технічний університет ім. Івана Пулюя, 2013. http://elartu.tntu.edu.ua/handle/123456789/2396.

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Робота виконана на кафедрі менеджменту підприємницької діяльності Тернопільського національного технічного університету імені Івана Пулюя Міністерства освіти і науки України. Захист відбувся у 2013 р. на засіданні спеціалізованої вченої ради К 58.052.05 у Тернопільському національному технічному університеті імені Івана Пулюя за адресою: м. Тернопіль, вул. Білогірська, 2, зал засідань. З дисертацією можна ознайомитися у бібліотеці Тернопільського національного технічного університету імені Івана Пулюя за адресою: 46001, м. Тернопіль, вул. Руська, 56.
Дисертація присвячена дослідженню теоретичних положень та розробленню практичних рекомендацій щодо формування конкурентоспроможних підприємницьких структур в умовах меблевого виробництва. На підставі дослідження й узагальнення літературних джерел висвітлено теоретичні основи конкурентних відносин у підприємницькому економічному середовищі. Узагальнено теоретичні засади, визначено основні напрями формування конкурентоспроможних підприємницьких структур та доцільність втручання держави у конкурентні відносини суб’єктів господарювання. Обґрунтовано необхідність використання структурно-інституціонального аналізу з метою визначення ступеня розвиненості конкурентних відносин підприємств на ринку продукції меблевого виробництва, запропоновано застосовувати інтегрований інструментарій щодо оцінювання стану конкурентного середовища з точки зору рівня розвитку конкуренції на ринку, удосконалено методику комплексного дослідження ринку меблевої продукції на основі проведення структурно-інституціонального аналізу, дістали подальшого розвитку теоретичні засади та основні напрями формування конкурентоспроможних підприємницьких структур, сформовано теоретико-концептуальну основу організаційного механізму управління конкурентоспроможністю підприємства меблевого виробництва
Диссертация направлена на решение проблем развития теоретических положений и разработке практических рекомендаций по формированию конкурентоспособных предпринимательских структур в условиях мебельного производства. Актуальность теми обусловлена тем, что для каждого субъекта хозяйствования важно его конкурентные преимущества, по различным параметрам обеспечивают ему рыночное преимущество над конкурентами. Эти преимущества можно рассматривать как с точки зрения эффективности производства, технической эффективности использования ресурсов, объективного распределения доходов, так и с позиций широкого перечня технико-технологических, политических и социальных факторов. Целью диссертационной работы является обобщение и развитие научно-теоретических основ, разработка и обоснование практических рекомендаций по формированию конкурентоспособных предпринимательских структур в условиях мебельного производства. Достижение поставленной цели обусловило решение следующих задач: усовершенствована методика комплексного исследования рынка мебельной продукции на основе проведения структурно-институционального анализа; предложено применять интегрированный инструментарий для оценки состояния конкурентной среды с точки зрения уровня развития конкуренции на нем; раскрыто исследование целесообразности вмешательства государства в конкурентные отношения субъектов хозяйствования; уточнено трактовку сущности конкурентных отношений в предпринимательской экономической среде; сформирована теоретико-концептуальная основа организационно-экономического механизма управления конкурентоспособностью предприятия мебельного производства; развиты теоретические основы и основные направления формирования конкурентоспособных предпринимательских структур. Объектом исследования являются организационно-экономические процессы, которые формируют уровень конкурентоспособности субъектов хозяйствования мебельной отрасли на внутреннем и внешнем рынках. Предметом исследования – теоретические и прикладные аспекты формирования конкурентоспособных предпринимательских структур в условиях мебельного производства. В первом разделе «Теоретико-прикладные особенности развития конкуренции в условиях предприятий мебельного производства» раскрыты теоретические основы конкурентных отношений в предпринимательской экономической среде как отношения между хозяйствующими субъектами, в основе которых лежат экономическое соперничество и борьба за доминирование на рынке за счет реализации выгодных условий производства и сбыта товаров, оказания услуг и обеспечения прибыльности предприятий, определена характеристика теоретических основ формирования конкурентоспособных предпринимательских структур в мебельном производстве, а также освещена роль государства в организации конкурентных отношений. Во втором разделе «Анализ методического инструментария формирования предпринимательских структур в конкурентной среде» проанализировано состояние конкурентной среды предприятий мебельного производства, обосновано использование структурно-институционального анализа при исследовании конкурентной среды предприятия, что позволит оценить степень монополизации и развития конкуренции на рынке мебельных товаров, а также обобщены методы оценки конкурентной среды предприятия на рынке товаров мебельного производства. В третьем разделе «Пути повышения конкурентоспособности предпринимательских структур в контексте мебельного производства» раскрыто векторные направления развития предприятий мебельного производства в контексте повышения их конкурентоспособности, предложены концептуальные основы формирования организационно-экономического механизма управления конкурентоспособностью предприятия мебельного производства, что позволит научно обоснованно влиять на этот процесс. Полученные результаты работы послужат научной основой в разработке концептуально-теоретических и методических основ формирования конкурентоспособных предпринимательских структур в условиях мебельного производства.
PhD thesisis concerned with an investigation of theoretical foundations and development practical recommendations for the formation of competitive entrepreneurial structures in furniture manufacturing. Based on the study and synthesis of the literature deals the theoretical foundations of competitive relations in entrepreneurial business environment was covered. The theoretical framework, the main directions of the development of competitive businesses and appropriateness of state intervention in the competitive relationship entities was generalized and defined in the thesis. The necessity of structural and institutional analysis the degree of development of competitive relations firms to market products furniture production was determined; the integrated tool for assessing the competitive environment in terms of the level of market competition was proposed; the consistency procedure integrated market research furniture products on the basis of structural and institutional analysis was improved; the theoretically foundations and main directions of the development of competitive businesses, the theoretical and conceptual framework of organizational control mechanism ensuring competitiveness furniture production was formed.

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Bouhouch, Lahoussine. "Élaboration des couches d'alliages NI-FE par voie électrolytique : Études électrique, magnétique et structurale." Nancy 1, 1988. http://www.theses.fr/1988NAN10089.

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Mécanismes, caractéristiques et facteurs influant le dépôt électrolytique. Techniques d'élaboration et de dosage du fer dans les alliages NI-FE déposés. Influence des conditions opératoires sur la nature et composition des alliages élaborés. Étude des propriétés électriques magnétiques et de l'influence des traitements thermiques sur la structure des alliages

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Souza, Hidalyn Theodory Clemente Mattos de. "Evolu??o top-hat hidrodin?mica em campos de velocidades peculiares primordiais." Universidade Federal do Rio Grande do Norte, 2012. http://repositorio.ufrn.br:8080/jspui/handle/123456789/16606.

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Made available in DSpace on 2014-12-17T15:14:57Z (GMT). No. of bitstreams: 1 HidalynTC_TESE.pdf: 3025002 bytes, checksum: 560b594294d11c4905312394b1d53359 (MD5) Previous issue date: 2012-02-16
Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
We investigate the cosmology of the vacuum energy decaying into cold dark matter according to thermodynamics description of Alcaniz & Lima. We apply this model to analyze the evolution of primordial density perturbations in the matter that gave rise to the first generation of structures bounded by gravity in the Universe, called Population III Objects. The analysis of the dynamics of those systems will involve the calculation of a differential equation system governing the evolution of perturbations to the case of two coupled fluids (dark matter and baryonic matter), modeled with a Top-Hat profile based in the perturbation of the hydrodynamics equations, an efficient analytical tool to study the properties of dark energy models such as the behavior of the linear growth factor and the linear growth index, physical quantities closely related to the fields of peculiar velocities at any time, for different models of dark energy. The properties and the dynamics of current Universe are analyzed through the exact analytical form of the linear growth factor of density fluctuations, taking into account the influence of several physical cooling mechanisms acting on the density fluctuations of the baryonic component of matter during the evolution of the clouds of matter, studied from the primordial hydrogen recombination. This study is naturally extended to more general models of dark energy with constant equation of state parameter in a flat Universe
Investigamos a cosmologia da energia do v?cuo decaindo em mat?ria escura fria de acordo com a descri??o termodin?mica de Alcaniz & Lima. Aplicamos esse modelo na an?lise da evolu??o de perturba??es de densidade primordiais na mat?ria que deram origem a primeira gera??o de estruturas ligadas pela gravidade no Universo, os chamados Objetos da Popula??o III. A an?lise da din?mica desses sistemas envolver? o c?lculo de um sistema de equa??es diferenciais que governam a evolu??o de perturba??es para o caso de dois fluidos acoplados (mat?ria escura e mat?ria bari?nica), modelados com um perfil Top-Hat baseado na perturba??o das equa??es da hidrodin?mica, uma ferramenta anal?tica eficiente para estudar as propriedades dos modelos de energia escura, como o comportamento do fator de crescimento linear e o ?ndice de crescimento, grandezas f?sicas intimamente relacionadas aos campos de velocidades peculiares em qualquer ?poca, para diferentes modelos de energia escura. As propriedades e a din?mica do Universo atual s?o analisadas atrav?s da forma anal?tica exata do fator de crescimento linear de flutua??es de densidade, levando em considera??o a influ?ncia de v?rios mecanismos f?sicos de esfriamento atuando sobre as flutua??es de densidade da componente bari?nica da mat?ria durante a evolu??o das nuvens de mat?ria, estudadas desde a recombina??o primordial do hidrog?nio. Esse estudo ? naturalmente estendido aos modelos mais gerais de energia escura com o par?metro da equa??o de estado constante em um Universo plano

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Bordairon, Marc. "Dimensionnement des massifs en sol renforcé par géosynthétiques." Grenoble INPG, 1986. http://www.theses.fr/1986INPG0113.

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Calcul des massifs de soutenement en terre renforcee par des nappes horizontales de geosynthetiques. Analyse detaillee d'une nouvelle "methode double blocs" et formalisee par une geometrie quelconque et des sollicitations diverses. Surface de glissement polygonale. Etude de l'influence de certains parametres (hauteur, sol, inclinaison du parement) sur le dimensionnement en vue de l'elaboration d'abaques de dimensionnement de massifs en sol renforce que l'on presente. Comparaison avec des methodes d'equilibre limite a surface de glissement circulaire. Resume des principales methodes traditionnelles pour des massifs a parements verticaux. Application de ces methodes sur des ouvrages de soutenement construits dans le departement de l'isere

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47

Moreira, Ana Sofia Pereira. "Study of modifications induced by thermal and oxidative treatment in oligo and polysaccharides of coffee by mass spectrometry." Doctoral thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/17074.

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Doutoramento em Bioquímica
Os polissacarídeos são os componentes maioritários dos grãos de café verde e torrado e da bebida de café. Os mais abundantes são as galactomananas, seguindo-se as arabinogalactanas. Durante o processo de torra, as galactomananas e arabinogalactanas sofrem modificações estruturais, as quais estão longe de estar completamente elucidadas devido à sua diversidade e à complexidade estrutural dos compostos formados. Durante o processo de torra, as galactomananas e arabinogalactanas reagem com proteínas, ácidos clorogénicos e sacarose, originando compostos castanhos de alto peso molecular contendo nitrogénio, designados de melanoidinas. As melanoidinas do café apresentam diversas atividades biológicas e efeitos benéficos para a saúde. No entanto, a sua estrutura exata e os mecanismos envolvidos na sua formação permanecem desconhecidos, bem como a relação estrutura-atividade biológica. A utilização de sistemas modelo e a análise por espectrometria de massa permitem obter uma visão global e, simultaneamente, detalhada das modificações estruturais nos polissacarídeos do café promovidas pela torra, contribuindo para a elucidação das estruturas e mecanismos de formação das melanoidinas. Com base nesta tese, oligossacarídeos estruturalmente relacionados com a cadeia principal das galactomananas, (β1→4)-Dmanotriose (Man3), e as cadeias laterais das arabinogalactanas, (α1→5)-Larabinotriose (Ara3), isoladamente ou em misturas com ácido 5-Ocafeoilquínico (5-CQA), o ácido clorogénico mais abundante nos grãos de café verde, e péptidos compostos por tirosina e leucina, usados como modelos das proteínas, foram sujeitos a tratamento térmico a seco, mimetizando o processo de torra. A oxidação induzida por radicais hidroxilo (HO•) foi também estudada, uma vez que estes radicais parecem estar envolvidos na modificação dos polissacarídeos durante a torra. A identificação das modificações estruturais induzidas por tratamento térmico e oxidativo dos compostos modelo foi feita por estratégias analíticas baseadas principalmente em espectrometria de massa, mas também em cromatografia líquida. A cromatografia de gás foi usada na análise de açúcares neutros e ligações glicosídicas. Para validar as conclusões obtidas com os compostos modelo, foram também analisadas amostras de polissacarídeos do café obtidas a partir de resíduo de café e café instantâneo. Os resultados obtidos a partir dos oligossacarídeos modelo quando submetidos a tratamento térmico (seco), assim como à oxidação induzida por HO• (em solução), indicam a ocorrência de despolimerização, o que está de acordo com estudos anteriores que reportam a despolimerização das galactomananas e arabinogalactanas do café durante a torra. Foram ainda identificados outros compostos resultantes da quebra do anel de açúcares formados durante o tratamento térmico e oxidativo da Ara3. Por outro lado, o tratamento térmico a seco dos oligossacarídeos modelo (individualmente ou quando misturados) promoveu a formação de oligossacarídeos com um maior grau de polimerização, e também polissacarídeos com novos tipos de ligações glicosídicas, evidenciando a ocorrência de polimerização através reações de transglicosilação não enzimática induzidas por tratamento térmico a seco. As reações de transglicosilação induzidas por tratamento térmico a seco podem ocorrer entre resíduos de açúcares provenientes da mesma origem, mas também de origens diferentes com formação de estruturas híbridas, contendo arabinose e manose como observado nos casos dos compostos modelo usados. Os resultados obtidos a partir de amostras do resíduo de café e de café instantâneo sugerem a presença de polissacarídeos híbridos nestas amostras de café processado, corroborando a ocorrência de transglicosilação durante o processo de torra. Além disso, o estudo de misturas contendo diferentes proporções de cada oligossacarídeo modelo, mimetizando regiões do grão de café com composição distinta em polissacarídeos, sujeitos a diferentes períodos de tratamento térmico, permitiu inferir que diferentes estruturas híbridas e não híbridas podem ser formadas a partir das arabinogalactanas e galactomananas, dependendo da sua distribuição nas paredes celulares do grão e das condições de torra. Estes resultados podem explicar a heterogeneidade de estruturas de melanoidinas formadas durante a torra do café. Os resultados obtidos a partir de misturas modelo contendo um oligossacarídeo (Ara3 ou Man3) e 5-CQA sujeitas a tratamento térmico a seco, assim como de amostras provenientes do resíduo de café, mostraram a formação de compostos híbridos compostos por moléculas de CQA ligadas covalentemente a um número variável de resíduos de açúcar. Além disso, os resultados obtidos a partir da mistura contendo Man3 e 5-CQA mostraram que o CQA atua como catalisador das reações de transglicosilação. Por outro lado, nas misturas modelo contendo um péptido, mesmo contendo também 5-CQA e sujeitas ao mesmo tratamento, observou-se uma diminuição na extensão das reações transglicosilação. Este resultado pode explicar a baixa extensão das reações de transglicosilação não enzimáticas durante a torra nas regiões do grão de café mais ricas em proteínas, apesar dos polissacarídeos serem os componentes maioritários dos grãos de café. A diminuição das reações de transglicosilação na presença de péptidos/proteínas pode dever-se ao facto de os resíduos de açúcares redutores reagirem preferencialmente com os grupos amina de péptidos/proteínas por reação de Maillard, diminuindo o número de resíduos de açúcares redutores disponíveis para as reações de transglicosilação. Além dos compostos já descritos, uma diversidade de outros compostos foram formados a partir dos sistemas modelo, nomeadamente derivados de desidratação formados durante o tratamento térmico a seco. Em conclusão, a tipificação das modificações estruturais promovidas pela torra nos polissacarídeos do café abre o caminho para a compreensão dos mecanismos de formação das melanoidinas e da relação estrutura-atividade destes compostos.
Polysaccharides are the major components of green and roasted coffee beans, and coffee brew. The most abundant ones are galactomannans, followed by arabinogalactans. During the roasting process, galactomannans and arabinogalactans undergo structural modifications that are far to be completely elucidated due to their diversity and complexity of the compounds formed. During the roasting process, galactomannans and arabinogalactans react with proteins, chlorogenic acids, and sucrose, originating high molecular weight brown compounds containing nitrogen, known as melanoidins. Several biological activities and beneficial health effects have been attributed to coffee melanoidins. However, their exact structures and the mechanisms involved in their formation remain unknown, as well as the structure-biological activity relationship. The use of model systems and mass spectrometry analysis allow to obtain an overall view and, simultaneously, detailed, of the structural modifications in coffee polysaccharides promoted by roasting, contributing to the elucidation of the structures and formation mechanisms of melanoidins. Based on this thesis, oligosaccharides structurally related to the backbone of galactomannans, (β1→4)-D-mannotriose, and the side chains of arabinogalactans, (α1→5)-Larabinotriose, alone or in mixtures with 5-O-caffeoylquinic acid, the most abundant chlorogenic acid in green coffee beans, and dipeptides composed by tyrosine and leucine, used as models of proteins, were submitted to dry thermal treatments, mimicking the coffee roasting process. The oxidation induced by hydroxyl radicals (HO•) was also studied, since these radicals seem to be involved in the modification of the polysaccharides during roasting. The identification of the structural modifications induced by thermal and oxidative treatment of the model compounds was performed mostly by mass spectrometry-based analytical strategies, but also using liquid chromatography. Gas chromatography was used in the analysis of neutral sugars and glycosidic linkages. To validate the conclusions achieved with the model compounds, coffee polysaccharide samples obtained from spent coffee grounds and instant coffee were also analysed. The results obtained from the model oligosaccharides when submitted to thermal treatment (dry) or oxidation induced by HO• (in solution) indicate the occurrence of depolymerization, which is in line with previous studies reporting the depolymerization of coffee galactomannans and arabinogalactans during roasting. Compounds resulting from sugar ring cleavage were also formed during thermal treatment and oxidative treatment of Ara3. On the other hand, the dry thermal treatment of the model oligosaccharides (alone or when mixed) promoted the formation of oligosaccharides with a higher degree of polymerization, and also polysaccharides with new type of glycosidic linkages, evidencing the occurrence of polymerization via non-enzymatic transglycosylation reactions induced by dry thermal treatment. The transglycosylation reactions induced by dry thermal treatment can occur between sugar residues from the same origin, but also of different origins, with formation of hybrid structures, containing arabinose and mannose in the case of the model compounds used. The results obtained from spent coffee grounds and instant coffee samples suggest the presence of hybrid polysaccharides in these processed coffee samples, corroborating the occurrence of transglycosylation during the roasting process. Furthermore, the study of mixtures containing different proportions of each model oligosaccharide, mimicking coffee bean regions with distinct polysaccharide composition, subjected to different periods of thermal treatment, allowed to infer that different hybrid and non-hybrid structures may be formed from arabinogalactans and galactomannans, depending on their distribution in the bean cell walls and on roasting conditions. These results may explain the heterogeneity of melanoidins structures formed during coffee roasting. The results obtained from model mixtures containing an oligosaccharide (Ara3 or Man3) and 5-CQA and subjected to dry thermal treatment, as well as samples derived from spent coffee grounds, showed the formation of hybrid compounds composed by CQA molecules covalently linked to a variable number of sugar residues. Moreover, the results obtained from the mixture containing Man3 and 5-CQA showed that CQA acts as catalyst of transglycosylation reactions. On the other hand, in the model mixtures containing a peptide, even if containing 5-CQA and subjected to the same treatment, it was observed a decrease in the extent of transglycosylation reactions. This outcome can explain the low extent of non-enzymatic transglycosylation reactions during roasting in coffee bean regions enriched in proteins, although polysaccharides are the major components of the coffee beans. The decrease of transglycosylation reactions in the presence of peptides/proteins can be related with the preferential reactivity of reducing residues with the amino groups of peptides/proteins by Maillard reaction, decreasing the number of reducing residues available to be directly involved in the transglycosylation reactions. In addition to the compounds already described, a diversity of other compounds were formed from model systems, namely dehydrated derivatives formed during dry thermal treatment. In conclusion, the identification of the structural modifications in coffee polysaccharides promoted by roasting pave the way to the understanding of the mechanisms of formation of melanoidins and structure-activity relationship of these compounds.

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48

Li, Wei Hsin, and 李偉新. "Study For The Formation Mechanism In II-VI Semiconductor Nano Structure." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/70655644250629215843.

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Анотація:

碩士
淡江大學
物理學系碩士班
96
This thesis is devoted to study the quantum dots’nano structure of formation mechanism in II-VI semiconductor and to observe the stability of QDs were capped by gold film.The experiment contains to observe nano structure of V-W mode and S-K mode epitaxy,and their mechanism of assembling and association;to cap the gold film on top of QDs and to compare with different thickness which affect structure stability of QDs;study of ZnSe nano hole; preview of special structure which is descried at experiment process. About experiment,to grow sample by a hot wall epitaxy(HWE) system.Use CdSe for material in V-W mode;use ZnSe for material in S-K mode.Then by changing proportion of admixture liquid,epitaxy thickness,mature period and controlling temperature of substrate,to make sample of each experiment.Next by using atomic force microscopy (AFM) to observe structure of substrate surface. The result of experiment descried that the structure of V-W mode epitaxy is more obvious than S-K mode epitaxy;capping gold film can stabilize nano structure effectively about 2 months;the process of making ZnSe nano hole.

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49

Tu, Ya-ting, and 杜雅婷. "The Study of Formation Mechanism and Stability of Rocksalt Structure MgZnO Epilayer." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/42n477.

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Анотація:

碩士
國立中山大學
材料與光電科學學系研究所
102
Alloying ZnO (Eg~3.3 eV) with MgO (Eg~7.7 eV) enables widening of band gap of ZnO. The coverage of the ZnO band gap will increase from the blue regime to the deep UV regime while adding more MgO to it. However, it is difficult to demonstrate an MgZnO alloy, which energy region lays between 4.3 and 5.4 eV, due to the structure problem between the wurtzite structure ZnO and the rock salt structure MgO. In this study, the effect of both the composition and the thickness of MgZnO on the phase stability of rock salt MgZnO was analyzed. The rock salt structure MgZnO epilayers was deposited on MgO (100) substrates by plasma-assisted molecular beam epitaxy (PAMBE), altering Zn flux/Mg flux ratio in order to get the MgZnO epilayers with different composition, altering growing time to get the MgZnO epilayers with different thickness. Following the MBE growth, the surface morphology of the epilayers was examined by scanning electron microscopy (SEM). The composition of the epilayers was measured by energy dispersive X-ray spectroscopy (EDS). Electron back- scattered diffraction (EBSD) and high resolution X-ray diffraction (XRD) were employed to collect the crystallographic information. Transmission electron microscopy (TEM) was used to characterize the microstructure and the orientation relationship. Results indicate that the ZMO epilayers with over 80% Zn will maintain the rock-salt structures even though the thickness of epilayers is slightly higher than the theoretical critical thickness. This is probably due to the large hysteresis of the reverse rock-slat-to-wurtzite transformation. On the other hand, wurtzite ZMO films having (101̅0) and (0002) preferred orientations were iv obtained when the molar fraction of Zn exceeds 0.8 or the thickness is much higher than the critical thickness. Two orientation relationships between the rock-salt and wurtzite ZMO were derived depending on the stress relaxation condition. An orientation relationship of (100)R //(101̅0)W，<011>R //<12̅13̅> W was found for the epilayer constrained by a biaxial stress condition, and another (11̅1)R //(01̅11)W，[011]R//[1̅21̅3]W orientation relationship was indentified in TEM samples which was compressed by a uniaxial stress. A simplified two-dimensional crystallographic phenomenological theory for martensitic transformation was used to explain the crystallographic characteristic of the phase transformation for the constrained epilayer.

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50

Lan, Fa-Tai, and 籃發泰. "Study on the formation mechanism of Sr2SiO4 using SrCO3/SiO2 core/shell structure." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/38144866845622620238.

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Анотація:

碩士
國立成功大學
資源工程學系碩博士班
97
The Sr2SiO4 can replace YAG as a phosphor material for white light emitting diodes (LEDs) due to its excellent chemical and thermal stability. Presently, Sr2SiO4 powder is mainly mass-produced using a solid-state reaction from SrCO3 and SiO2. But, the conventional high-temperature solid-state reaction easily leads to coarsening and particle agglomerations. On the other hand, the reaction mechanism between SrCO3 and SiO2 for formation of the Sr2SiO4 is not well understood so far. In this study, the SrCO3 -SiO2 core-shell structure was prepared to reduce the heat treatment temperature and the Sr2SiO4 formation mechanism was discussed. The experimental results indicate that the surface coating SrCO3 with SiO2 raises the contact area and mixture homogeneity of reactants, which promotes the interfacial reaction to from Sr2SiO4 and reduces Sr2SiO4 formation temperature drastically due to the decrease of the diffusion distance. Since the reaction temperature is too low to result in the decomposition of SrCO3, the mechanism in this stage is suggested to be dominated by the silicon diffusion. However, when the reaction temperature is higher than the decomposition temperature of pure SrCO3, the mechanism can be dominated by the strontium diffusion. Using the SrCO3 -SiO2 core-shell structure, the Sr2SiO4 powder can be successfully prepared at a temperature as low as 800℃.

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