Academic literature on the topic 'Hybrid Aggregates'

Spectral properties of mixtures of Zn0.7Sd0.3S colloidal quantum dots with mean diameter value of 3.5 nm with the molecules of 3,3'-di(γ-sulfopropil)-9-ethyl-4,5,4',5'-dibenzo-thiacarbocyanine betaine pyridine salt (DEC), prepared in gelatin were investigated. The obtained data indicated that the formation of well-luminescent trans-J-aggregates and spectral tuning in the position of the absorption band of DEC and the luminescence band of quantum dots, providing requirements for resonant energy transfer in the hybrid associate are the determinant factors in the increase of the luminescent emission of DEC molecules, interacting with Zn0.7Cd0.3S colloidal quantum dots. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35329

Pluripotent embryonic stem cells (ESCs) can differentiate into all somatic cell types, making them a useful platform for studying a variety of cellular phenomenon. Furthermore, ESCs can be induced to form aggregates called embryoid bodies (EBs) which recapitulate the dynamics of development and morphogenesis. However, many different factors such as gradients of soluble morphogens, direct cell-to-cell signaling, and cell-matrix interactions have all been implicated in directing ESC differentiation. Though the effects of individual factors have often been investigated independently, the inherent difficulty in assaying combinatorial effects has made it difficult to ascertain the concerted effects of different environmental parameters, particularly due to the spatial and temporal dynamics associated with such cues. Dynamic computational models of ESC differentiation can provide powerful insight into how different cues function in combination both spatially and temporally. By combining particle based diffusion models, cellular agent based approaches, and physical models of morphogenesis, a multi-scale, rules-based modeling framework can provide insight into how each component contributes to differentiation. I propose to investigate the complex regulatory cues which govern complex morphogenic behavior in 3D ESC systems via a computational rules based modeling approach. The objective of this study is to examine how spatial patterns of differentiation by ESCs arise as a function of the microenvironment. The central hypothesis is that spatial control of soluble morphogens and cell-cell signaling will allow enhanced control over the patterns and efficiency of stem cell differentiation in embryoid bodies.

The different stages of technological evolution are characterized in terms of the dominant type of tools used in each of them. We passed through the `stone age', the `copper age' and the `iron age' and now we are probably in the `electron age'. After having done a wonderful job, today it looks as if electronic technologies have started experiencing their limits. For example, today's `information explosion' and communication problems demand very large bandwidths without cross talk, larger than that electronics can provide. What could be the technology that can tackle the growing needs of tomorrow? Photonics is being studied today as a possible alternate technology for the future. Investigations are on to harness the capability of the photon to carry information and energy. Fortunately, success has already been achieved in the area of communications. Optical fibers, not copper cables, are already being used to carry huge amounts of information across the great oceans. However, among the three “C”s (communication, computing and control), communication is the only one that is currently implying photonic devices. Photonic switches and optical computers are still in the laboratories and not yet in the marketplace. The major bottleneck in this area is not in solving technological problems or in perfecting theoretical understanding, but in developing suitable materials. In this field, materials with non linear optical (NLO) properties seem to be extremely appealing in fact NLO effects allow the manipulation of laser light beams, extending the frequency range provided by normal laser sources into the ultraviolet and infrared regions, and may thus form the basis of all-optical computing devices. In order to be implied in a device, the NLO materials must satisfy some requirement such as good NLO properties, high laser damage threshold, fast optical response time, wide phase matchable angle, architectural flexibility for molecular design and morphology, ability to process into crystals and thin films, optical transparency (no absorption at fundamental and SH wavelengths), synthetically facile, environmental friendly and high mechanical strength and thermal stability. During this three-year research the attention was to the synthesis and the investigation of the second harmonic NLO properties of new organic and inorganic-organic hybrid material. NLO characterization has been performed in solution using the EFISH technique, the Kurtz-Perry method has been implied for the measurements in the solid state while the Maker’s fringe technique has been use for measurements on film. In the field of inorganic-organic hybrid materials, the synthesis of new members of the family of compounds with general formula [DAMS]4[MIII2MII(C2O4)6]2•DAMBA•2H2O (where MIII = Rh, Fe, Cr; MII = Co, Ni, DAMS = trans-4-(4-dimethylaminostyryl)-1-methylpyridinium; DAMBA = para-dimethylamino benzaldeide) has been prepared and, in particular, the derivatives containing CoII and NiII have been isolated by slight modification of the synthesis reported by Cariati et al. for the MnII and ZnII derivatives. The SHG of these new materials is extremely high, of the same order on magnitude of DAST (trans-4-(4-dimethylaminostyryl)-1-methylpyridinium p-toluensulfonate) and it is related to the organization into J aggregates of the [DAMS+] chromophores. These materials are not only interesting for their SHG but also for the tuning of their magnetic properties by varying the MII/MIII couple. During the optimization of the synthesis of these compounds, a phase containing only [DAMS]I and DAMBA has been isolated. The [DAMS+] chromophores are organized in colums in a configuration typical of J aggregates and the presence of the templating agent DAMBA induces the arrangement of the colums in a fish-bone-like architecture. The SHG of this new compound is, once again, related to the presence on J aggregates. The tendency to form J aggregates of [DAMS+] chromophores has also been exploited in the preparation of film of DAST in poly(methyl methacrylate (PMMA) with high, stable and long-lasting SHG using the Poling technique. The in situ growth of homogeneously dispersed oriented nanocrystals with sizes of less than 100 nm has been observed in PMMA films with 4 wt% of the ionic second order NLO chromophore DAST obtained by spincoating of CHCl3–CH3OH (2/1) solutions. This is achieved by a two step process: corona poling at 8 kV and 90°C followed, in the absence of electric field, by controlled thermal annealing up to 140°C. The investigation of the NLO properties has also been extended to chromophores in solution and the molecular hyperpolarizability has been determinate by EFISH technique. Of particular interest is the compound 8-N,N-dibutylamino-2-azachrysene which is characterized by a large hyperpolarizability value and very high thermal stability, properties that make it good candidate as building block for NLO active materials. Particular interest has been given to solid state luminescent materials for their growing interest both from a scientific and a technological point of view. Aggregation caused quenching (ACQ) processes however represent an obstacle to the development of most luminogens in the condensed phase. This is why particularly fascinating are those materials showing higher emission intensity in the solid state than in solution. In this filed, the emissive properties of the molecule 4-dimethylamino-2-benzylidene malonic acid dimethyl ester, a very simple push-pull molecule have been investigated. It is weakly emissive in solution and in the amorphous phase but becomes highly emissive in the crystalline phase according to what has been indicated as Crystallization Induced Emission (CIE). Thanks to combined emission, 1H and 13C NMR spectroscopies, it has been demonstrated that a restricted intramolecular rotation (RIR) phenomen is at the origin of this behavior. Moreover this molecule possesses interesting acidochromic properties opening to sensor and optoelectronic applications. During a 7 months research period spent at UCSB (University of California, Santa Barbara) in Prof. Ford’s laboratories, the synthesis and characterization of Cu(I) complexes with a photolabile CS2 moiety have been studied. In particular, two new complexes have been obtained: [Cu(dmp)(PPh3)(tBuOOC-CS2)] (dmp = 2,9-dimethyl-1,10- phenanthroline, tBuOOC-CS2 = O-t-butyl-1,1- dithiooxalate ester ) is a rare example of tetracoordinated CuI complex with three different ligands while [Cu(tBuOOC-CS3)(Br)][PPh3Bz] is an air stable threecoordinated CuI complex. Further study has to be performed in order to determine whether or not CS2 is photogenerated upon irradiation with visible light.

L’objectif de cette thèse est la préparation de matériaux hybrides polymères conjugués (P3HT et un copolymère dérivé) - nanotubes de carbone, ainsi que leur caractérisation par des méthodes spectroscopiques et par microscopie électronique. Des nanohybrides non-covalents sont obtenus par la sonication des deux composants dans le THF. L’interaction entre ces composants entraîne l’enroulement du polymère autour des nanotubes ainsi que la formation d'agrégats de polymère sur leur surface. L’effet de différents paramètres, tels que la masse molaire du polymère, ont été étudiés. Des nanohybrides covalents sont obtenus en utilisant un copolymère portant une aniline au bout de la chaîne alkyle. Les spectroscopies optique et Raman suggèrent un faible taux de fonctionnalisation ainsi qu’une conformation plus désordonnée des chaînes de polymères par rapport aux nanohybrides non-covalents. Des études préliminaires montrent que le copolymère peut fonctionnaliser aussi des dispositifs à base de nanotubes de carbone. Le bas taux de fonctionnalisation ne permet pas de conclure sur la modification des propriétés électroniques, mais les défauts induits permettent l’observation d’un photocourant<br>The objective of this thesis is the preparation of conjugated polymers (P3HT and a derivated copolymer) – carbon nanotubes hybrid materials and their characterization through different spectroscopies and transmission electron microscopy. Non-covalent nanohybrids can be obtained by sonicating both components together in THF. The interaction between both components leads to the wrapping of the polymer around the carbon nanotubes as well as the formation of polymer aggregates on the surface of the nanotubes. The effect of different parameters such as the polymer chain length are described. Covalent nanohybrids can be obtained using a specially designed copolymer bearing an aniline at the end of its side chain. Optical and Raman spectroscopies indicate a low level of functionalization, and suggest that the polymer chains are in a more disordered state compared to non-covalent nanohybrids. Preliminary studies show that the obtained copolymer can be used for functionalizing carbon nanotube based devices. Modification of electrical properties of the devices were small and compatible with the low functionalization degree, but the induced defects allow observation of a photocurrent

O uso e estudo de materiais híbridos para desenvolver novos materiais com qualidades superiores para aplicações em fotônica, sensores e áreas afins é um desafio para o químico. Neste contexto deve-se especular sobre as propriedades de associação de materiais orgânicos e inorgânicos para alcançar novas e melhores propriedades. Neste estudo, os óxidos metálicos (óxidos de cério em particular), uma classe especial entre nanopartículas inorgânicas, foram selecionados para explorar as suas aplicações com uma classe, também especial de compostos orgânicos, sendo no nosso estudo as Naftaleno Diimidas. Óxido de cério é um semicondutor, com uma &#8220;bandgap&#8221; larga, conhecido por sua capacidade catalítica e por sua simples manipulação para preparar filmes finos e nanopartículas. Derivados de Naftaleno Diimidas são conhecidos por sua superior atividade eletroquímica comparáveis aos dos Paraquat (metilviologênio), mas com amplitude maior de aplicações fotoquímicas. Foram sintetizadas Naftaleno Diimidas carregados positivamente e negativamente com propriedades surfactantes. Após a caracterização detalhada das Naftaleno Diimidas, incluindo auto-associação e interação com moléculas de surfactantes, a interação com nanopartículas de óxido de cério foram determinadas. As Naftaleno Diimidas interagiram de forma especial com nanopartículas de óxido de cério conferindo ausência de atividade hidrolítica e um comportamento fotocrômico singular. Propõe-se que o corante orgânico se adsorve nas ranhuras das nanopartículas e, além disso forma dímeros estáveis que têm importância para as novas fotoatividades observadas.<br>The use and study of hybrid materials is a challenge for the chemist to develop materials having new and superior qualities for applications in photonics, sensors and related areas. In this context one has to speculate on the properties of the organic and inorganic partners to achieve better and new properties. In this study the metal oxides (in particular Cerium Oxides), a special class among inorganic nanoparticles were selected to exploit their applications with an also special class of organic compounds the Naphthalene Diimides. Cerium Oxide is a wide bandgap semiconductor well known for its catalytic capabilities and for its simple manipulation to prepare thin films and nanoparticles. Naphthalene Diimides derivatives are known for their superior lectrochemical activities comparable to those of Paraquat (Methyl Viologen) but with larger amplitude of photochemical applications. Positively and negatively charged, surfactant like, Naphthalene Diimides, were synthesized. After detailed characterization of the Naphthalene Diimides including selfassociation and interaction with surfactant molecules, the interaction with Cerium Oxide nanoparticles was determined. Naphthalene Diimides interacted in a special manner with Cerium Oxide nanoparticles rendering hydrolytic inertness and novel photochromic behavior. The organic dye is proposed to adsorb in the crevices of the particles and furthermore forming stable dimers that accounts for the new photoactivities observed

Šiame darbe pristatomas PLA formalizmo metodas, skirtas aprašyti ir imituoti hibridines sistemas, kurių tolydiniai komponentai aprašomi pirmos eilės diferencialinėmis lygtimis. Pasinaudojus PLA formalizmu suformuluosime Kvantuotų būsenų sistemos modelį (QSS). QSS modelis yra integravimu pagrįstas metodas, skirtas spręsti pirmos eilės diferencialines lygtis. Šis modelis buvo suformuluotas DEVS formalizmo aplinkoje, kuris yra giminingas PLA formalizmui. Hibridinės sistemos pavyzdžiu pasirinktas farmakokinetinis modelis. Farmakokinetika yra farmakologijos mokslo šaka, tyrinėjant vartojamų vaistų pasisavinimą ir absorbciją žmogaus kūne. Farmakokinetiniame modelyje vaistų pasiskirstymas aprašomas pirmos eilės diferencialines lygtimis. Tam, kad būtų galima aprašyti šį modelį QSS pagalba, buvo reikalinga patobulinti QSS modelį. Rezultate gautas pakeistas QSS modelis. Naudojant pakeistą QSS modelį buvo sudarytas farmakokinetinis modelis ir atliktas vaistų koncentracijos kitimo imitavimas paciento kūne, kai pacientas reguliuoja vaistų suleidimą.<br>This paper presents the method of using Piece Linear Aggregates formalism (PLA) for specification and simulation of hybrid systems, when continuous components are described in ordinary differential equations (ODEs). PLA is used to create Quantized State System (QSS) model. QSS is integration based method, created for ODE solving. Since QSS method first was introduced for use in Discreet Event Systems (DEVS) formalism, we adapted it for PLA formalism, which is fundamentally consanguineous to DEVS formalism. Pharmacokinetics model is used as example of hybrid system. Pharmacokinetics is a branch of pharmacology which describes administered drug absorption and distribution in human body. In pharmacokinetics drug distribution is described using ODE. In order to use drug injection in pharmacokinetics model, we have to modify standard QSS model and add some specific capabilities. In the result: modified QSS method was obtained and used for pharmacokinetic model specification. Simulation of morphine concentration in plasma was performed using real pharmacokinetics data to test Patient-Controlled Analgesia method effectiveness.

Les nanocomposites polymères ont fait l'objet de recherches académiques et industrielles au cours des dernières décennies, du fait de leurs remarquables propriétés mécaniques et rhéologiques comparés aux polymères purs. En particulier, ils présentent du renforcement pour des fractions volumiques modérées, et des effets non linéaires pour des déformations relativement faibles. Malgré des décennies de recherche, la relation entre la rhéologie et la structure des nanocomposites est loin d'être comprise. Les simulations atomistiques peuvent donner une vision détaillée de l'interaction entre la dynamique des chaînes polymères et les charges renforçantes à une échelle locale. Cependant, il est difficile d'aborder les propriétés émergentes à une échelle mésoscopique, par exemple, simuler un grand nombre d'agrégats dans une matrice polymère enchevêtrée reste toujours hors de portée. Dans ce travail, nous proposons un modèle mésoscopique pour simuler la rhéologie des nanocomposites avec un fluide simple ou une matrice polymère enchevetrée, en utilisant la dynamique brownienne et la dynamique généralisée de Langevin, respectivement. Dans les deux dynamiques, le mouvement des chaines de polymère n'est pas décrit de façon explicite et son effet sur la dynamique de la charge est «moyenné». En utilisant ce modèle, nous étudions l'influence du type de charge, de leur taille, morphologie, et fraction volumique sur la rhéologie du composite modèle, ainsi que la morphologie des charges dans les simulations. Un cas particulièrement intéressant est celui d'agrégats quasi-fractals, qui peuvent être flexibles ou bien rigides. Nous démontrons que les systèmes avec agrégats présentent un renforcement significatif, qui augmente avec la taille des agrégats, leur rigidité, leur fraction volumique et leur polydispersité en taille. Une relaxation lente est également mise en évidence, et nous montrons qu'elle est liée à la rotation lente des agrégats. L'effet Payne, associé à la réponse non linéaire des modules dynamiques avec l'amplitude de déformation de cisaillement, est également observé pour nos modèles de composites. Nous faisons le lien entre l'arrangement microscopique des charges sous cisaillement et les propriétés macroscopiques du composite<br>Polymer nanocomposites have drawn a lot of attention both from the academic and industrial research in the last decades, thanks to their remarkable mechanical and rheological properties as compared to pure polymers. In particular, they may display reinforcement for moderate volume fractions, and several non linear effects that appear for small deformation amplitudes. In spite of decades of research, the relation between nanocomposites structure and rheology is far from being understood. Atomistic simulations can give a detailed view of the interplay between polymer chains dynamics and fillers at a local scale. However, it is much more difficult to address the properties emerging at a mesoscopic scale, for instance, to simulate a large number of aggregates in an entangled polymeric matrix remains out of reach. In this work, we build a mesoscopic model to simulate the rheology of polymer nanocomposites with a simple fluid and an entangled polymer matrix, by using the Brownian dynamics and the generalized Langevin dynamics, respectively. In both cases, the motion of the polymer chains is not explicitly described and its effect on the filler dynamics is "averaged out". Using this model, we quantitatively determine the influences of the filler type, the filler volume fraction, size and morphology on the rheology of the model composite. Of particular interest is the case of fractal-like aggregates, which may be flexible or rigid. We demonstrate that model aggregates display significant reinforcement, which increases with the aggregate size, aggregate rigidity, filler volume fraction and polydispersity. Long relaxation times are also evidenced, which are related to the slow rotation of the aggregates. The well-known Payne effect, associated to the nonlinear response of the dynamic moduli with the shear deformation amplitude, is also seen in our model composites. We relate the behavior of microscopic filler to the macroscopic properties of the composite

High level of intermittent renewable generation such as PV plants and wind farms will require distributed storage systems to meet the power system frequency operation standards. This thesis proposes a rule-based controller to co-ordinate the renewables and distributed energy storage system for improving frequency response.