10,191 research outputs found

    The extended Ville's inequality for nonintegrable nonnegative supermartingales

    Full text link
    Following initial work by Robbins, we rigorously present an extended theory of nonnegative supermartingales, requiring neither integrability nor finiteness. In particular, we derive a key maximal inequality foreshadowed by Robbins, which we call the extended Ville's inequality, that strengthens the classical Ville's inequality (for integrable nonnegative supermartingales), and also applies to our nonintegrable setting. We derive an extension of the method of mixtures, which applies to σ\sigma-finite mixtures of our extended nonnegative supermartingales. We present some implications of our theory for sequential statistics, such as the use of improper mixtures (priors) in deriving nonparametric confidence sequences and (extended) e-processes

    Limit theorems for non-Markovian and fractional processes

    Get PDF
    This thesis examines various non-Markovian and fractional processes---rough volatility models, stochastic Volterra equations, Wiener chaos expansions---through the prism of asymptotic analysis. Stochastic Volterra systems serve as a conducive framework encompassing most rough volatility models used in mathematical finance. In Chapter 2, we provide a unified treatment of pathwise large and moderate deviations principles for a general class of multidimensional stochastic Volterra equations with singular kernels, not necessarily of convolution form. Our methodology is based on the weak convergence approach by Budhiraja, Dupuis and Ellis. This powerful approach also enables us to investigate the pathwise large deviations of families of white noise functionals characterised by their Wiener chaos expansion as~Xε=n=0εnIn(fnε).X^\varepsilon = \sum_{n=0}^{\infty} \varepsilon^n I_n \big(f_n^{\varepsilon} \big). In Chapter 3, we provide sufficient conditions for the large deviations principle to hold in path space, thereby refreshing a problem left open By Pérez-Abreu (1993). Hinging on analysis on Wiener space, the proof involves describing, controlling and identifying the limit of perturbed multiple stochastic integrals. In Chapter 4, we come back to mathematical finance via the route of Malliavin calculus. We present explicit small-time formulae for the at-the-money implied volatility, skew and curvature in a large class of models, including rough volatility models and their multi-factor versions. Our general setup encompasses both European options on a stock and VIX options. In particular, we develop a detailed analysis of the two-factor rough Bergomi model. Finally, in Chapter 5, we consider the large-time behaviour of affine stochastic Volterra equations, an under-developed area in the absence of Markovianity. We leverage on a measure-valued Markovian lift introduced by Cuchiero and Teichmann and the associated notion of generalised Feller property. This setting allows us to prove the existence of an invariant measure for the lift and hence of a stationary distribution for the affine Volterra process, featuring in the rough Heston model.Open Acces

    Gasificação direta de biomassa para produção de gás combustível

    Get PDF
    The excessive consumption of fossil fuels to satisfy the world necessities of energy and commodities led to the emission of large amounts of greenhouse gases in the last decades, contributing significantly to the greatest environmental threat of the 21st century: Climate Change. The answer to this man-made disaster is not simple and can only be made if distinct stakeholders and governments are brought to cooperate and work together. This is mandatory if we want to change our economy to one more sustainable and based in renewable materials, and whose energy is provided by the eternal nature energies (e.g., wind, solar). In this regard, biomass can have a main role as an adjustable and renewable feedstock that allows the replacement of fossil fuels in various applications, and the conversion by gasification allows the necessary flexibility for that purpose. In fact, fossil fuels are just biomass that underwent extreme pressures and heat for millions of years. Furthermore, biomass is a resource that, if not used or managed, increases wildfire risks. Consequently, we also have the obligation of valorizing and using this resource. In this work, it was obtained new scientific knowledge to support the development of direct (air) gasification of biomass in bubbling fluidized bed reactors to obtain a fuel gas with suitable properties to replace natural gas in industrial gas burners. This is the first step for the integration and development of gasification-based biorefineries, which will produce a diverse number of value-added products from biomass and compete with current petrochemical refineries in the future. In this regard, solutions for the improvement of the raw producer gas quality and process efficiency parameters were defined and analyzed. First, addition of superheated steam as primary measure allowed the increase of H2 concentration and H2/CO molar ratio in the producer gas without compromising the stability of the process. However, the measure mainly showed potential for the direct (air) gasification of high-density biomass (e.g., pellets), due to the necessity of having char accumulation in the reactor bottom bed for char-steam reforming reactions. Secondly, addition of refused derived fuel to the biomass feedstock led to enhanced gasification products, revealing itself as a highly promising strategy in terms of economic viability and environmental benefits of future gasification-based biorefineries, due to the high availability and low costs of wastes. Nevertheless, integrated techno economic and life cycle analyses must be performed to fully characterize the process. Thirdly, application of low-cost catalyst as primary measure revealed potential by allowing the improvement of the producer gas quality (e.g., H2 and CO concentration, lower heating value) and process efficiency parameters with distinct solid materials; particularly, the application of concrete, synthetic fayalite and wood pellets chars, showed promising results. Finally, the economic viability of the integration of direct (air) biomass gasification processes in the pulp and paper industry was also shown, despite still lacking interest to potential investors. In this context, the role of government policies and appropriate economic instruments are of major relevance to increase the implementation of these projects.O consumo excessivo de combustíveis fósseis para garantir as necessidades e interesses da sociedade conduziu à emissão de elevadas quantidades de gases com efeito de estufa nas últimas décadas, contribuindo significativamente para a maior ameaça ambiental do século XXI: Alterações Climáticas. A solução para este desastre de origem humana é de caráter complexo e só pode ser atingida através da cooperação de todos os governos e partes interessadas. Para isto, é obrigatória a criação de uma bioeconomia como base de um futuro mais sustentável, cujas necessidades energéticas e materiais sejam garantidas pelas eternas energias da natureza (e.g., vento, sol). Neste sentido, a biomassa pode ter um papel principal como uma matéria prima ajustável e renovável que permite a substituição de combustíveis fósseis num variado número de aplicações, e a sua conversão através da gasificação pode ser a chave para este propósito. Afinal, na prática, os combustíveis fósseis são apenas biomassa sujeita a elevada temperatura e pressão durante milhões de anos. Além do mais, a gestão eficaz da biomassa é fundamental para a redução dos riscos de incêndio florestal e, como tal, temos o dever de utilizar e valorizar este recurso. Neste trabalho, foi obtido novo conhecimento científico para suporte do desenvolvimento das tecnologias de gasificação direta (ar) de biomassa em leitos fluidizados borbulhantes para produção de gás combustível, com o objetivo da substituição de gás natural em queimadores industriais. Este é o primeiro passo para o desenvolvimento de biorrefinarias de gasificação, uma potencial futura indústria que irá providenciar um variado número de produtos de valor acrescentado através da biomassa e competir com a atual indústria petroquímica. Neste sentido, foram analisadas várias medidas para a melhoria da qualidade do gás produto bruto e dos parâmetros de eficiência do processo. Em primeiro, a adição de vapor sobreaquecido como medida primária permitiu o aumento da concentração de H2 e da razão molar H2/CO no gás produto sem comprometer a estabilidade do processo. No entanto, esta medida somente revelou potencial para a gasificação direta (ar) de biomassa de alta densidade (e.g., pellets) devido à necessidade da acumulação de carbonizados no leito do reator para a ocorrência de reações de reforma com vapor. Em segundo, a mistura de combustíveis derivados de resíduos e biomassa residual florestal permitiu a melhoria dos produtos de gasificação, constituindo desta forma uma estratégia bastante promissora a nível económico e ambiental, devido à elevada abundância e baixo custo dos resíduos urbanos. Contudo, devem ser efetuadas análises técnico-económicas e de ciclo de vida para a completa caraterização do processo. Em terceiro, a aplicação de catalisadores de baixo custo como medida primária demonstrou elevado potencial para a melhoria do gás produto (e.g., concentração de H2 e CO, poder calorífico inferior) e para o incremento dos parâmetros de eficiência do processo; em particular, a aplicação de betão, faialite sintética e carbonizados de pellets de madeira, demonstrou resultados promissores. Finalmente, foi demonstrada a viabilidade económica da integração do processo de gasificação direta (ar) de biomassa na indústria da pasta e papel, apesar dos parâmetros determinados não serem atrativos para potenciais investidores. Neste contexto, a intervenção dos governos e o desenvolvimento de instrumentos de apoio económico é de grande relevância para a implementação destes projetos.Este trabalho foi financiado pela The Navigator Company e por Fundos Nacionais através da Fundação para a Ciência e a Tecnologia (FCT).Programa Doutoral em Engenharia da Refinação, Petroquímica e Químic

    Desegmentalization: towards a common framework for the modeling of tonogenesis and registrogenesis in mainland Southeast Asia with case studies from Austroasiatic

    Get PDF
    Suprasegmental contrasts of tone and register are commonplace phonological phenomena among the languages of Mainland Southeast Asia and its periphery (MSEA) (Matisoff 1990, 2001). Insofar as we have come to understand the origins and evolution of such contrasts, two theories predominate: tonogenesis (Haudricourt 1954) and registrogenesis (Huffman 1976). In their classical forms, tonogenesis and registrogenesis are well suited for modeling the development of tone and register in the best known, most studied languages of MSEA, but there is much additional complexity that they fail to capture. This is especially true for languages of Austroasiatic stock, which in many cases have developed tone and register in ways that must be considered ‘unorthodox’ with respect to the received models (Ferlus 1979, 2004, 2011; Diffloth 1982a, 1982b; Svantesson 1989; Gehrmann 2015; Sidwell 2015, 2019). The goal of this thesis is to present a possible way forward towards a unified conceptual framework for tone and register evolution in the languages of MSEA: desegmentalization. Expanding on Dockum’s (2019) concept of desegmental phonology, desegmentalization is the process by which one or more segmental properties (onset phonation, vowel height, vowel length or coda phonation) condition changes in the distribution of a language’s suprasegmental contrasts. A general survey of the Austroasiatic language family is presented, in which documented examples of desegmentalization are presented and discussed. Austroasiatic constitutes a useful laboratory for such a survey, because the identification of the segmental origins of suprasegmental contrasts in Austroasiatic languages is relatively straightforward in comparison to the other language families of MSEA. Based on this survey of desegmentalization processes in Austroasiatic, ten discrete desegmentalization models are proposed. The output typologies for the suprasegmental contrasts produced by each model are compared and implications for a general model of tonogenesis and registrogenesis are explored. This thesis offers (1) a digestible introduction for the non-specialist to the historical development of suprasegmental contrast in MSEA, (2) a resynthesis of current tonogenetic theory which integrates classical tonogenesis, classical registrogenesis and various other, lesser-known evolutionary pathways under the larger umbrella of desegmentalization and (3) a comprehensive overview of tone and register origins in the Austroasiatic family

    Managing global virtual teams in the London FinTech industry

    Get PDF
    Today, the number of organisations that are adopting virtual working arrangements has exploded, and the London FinTech industry is no exception. During recent years, FinTech companies have increasingly developed virtual teams as a means of connecting and engaging geographically dispersed workers, lowering costs, and enabling greater speed and adaptability. As the first study in the United Kingdom regarding global virtual team management in the FinTech industry, this DBA research seeks answers to the question, “What makes for the successful management of a global virtual team in the London FinTech industry?”. Straussian grounded-theory method was chosen as this qualitative approach lets participants have their own voice and offers some flexibility. It also allows the researcher to have preconceived ideas about the research undertaking. The research work makes the case for appreciating the voice of people with lived experiences. Ten London-based FinTech Managers with considerable experience running virtual teams agreed to take part in this study. These Managers had spent time working at large, household-name firms with significant global reach, and one had recently become founder and CEO of his own firm, taking on clients and hiring contract staff from around the world. At least eight of the other participants were senior ‘Heads’ of various technology teams and one was a Managing Director working at a ‘Big Four’ consultancy. They had all (and many still did) spent years running geographically distributed teams with members as far away as Pacific Asia and they were all keen to discuss that breadth of experience and the challenges they faced. Results from these in-depth interviews suggested that there are myriad reasons for a global virtual team, from providing 24 hour, follow-the-sun service to locating the most cost-effective resources with the highest skills. It also confirmed that there are unique challenges to virtual management and new techniques are required to help navigate virtual managers through them. Managing a global virtual team requires much more than the traditional management competencies. Based on discussion with the respondents, a set of practical recommendations for global virtual team management was developed and covered a wide range of issues related to recruitment and selection, team building, developing standard operating procedures, communication, motivation, performance management, and building trust

    International Conference on Mathematical Analysis and Applications in Science and Engineering – Book of Extended Abstracts

    Get PDF
    The present volume on Mathematical Analysis and Applications in Science and Engineering - Book of Extended Abstracts of the ICMASC’2022 collects the extended abstracts of the talks presented at the International Conference on Mathematical Analysis and Applications in Science and Engineering – ICMA2SC'22 that took place at the beautiful city of Porto, Portugal, in June 27th-June 29th 2022 (3 days). Its aim was to bring together researchers in every discipline of applied mathematics, science, engineering, industry, and technology, to discuss the development of new mathematical models, theories, and applications that contribute to the advancement of scientific knowledge and practice. Authors proposed research in topics including partial and ordinary differential equations, integer and fractional order equations, linear algebra, numerical analysis, operations research, discrete mathematics, optimization, control, probability, computational mathematics, amongst others. The conference was designed to maximize the involvement of all participants and will present the state-of- the-art research and the latest achievements.info:eu-repo/semantics/publishedVersio

    Buddhist Poetics, Beat “Cosmo-Politics,” and the Maker Ethos: Asian Americanist Critiques of Whiteness in Midcentury American Beat Writing

    Get PDF
    Buddhist Poetics, Beat “Cosmo-Politics,” and the Maker Ethos: Asian Americanist Critiques of Whiteness in Midcentury American Beat Writing employs Walter Benjamin’s notion of the “ruin”—which is not just a noun or notion, but also a verb, a mode of criticism—to intervene in the ostensibly well-trodden ground of what is known as “Beat literature.” The project broadly argues for the “ruination” of Beat literature, where ruination means not destruction or annihilation, but a return to an unkempt state (as in the image of a ruined building) that more accurately reflects this literature’s many layers of cultural, interpersonal, and transpacific exchange and extraction. Though many have rightly suggested that Beat literature is broadly Orientalist and transpacific in nature, I reveal the specific cultural appropriations, adaptations, and translations that occurred in this period and in these literary texts: the broadly East Asian cultural materials (like Zen Buddhism) so valued in Beat literature and its social communities were derived not solely from “the East” nor from translated Chinese and Japanese texts, but also from the Asians in America with whom Euro Americans were friends and worked alongside. My chapters on Asian diasporic poetry, letters, and autobiographical writing highlight Beat literature’s connections to ethnic studies, settler colonial studies, gender studies, and critical race theory, applying an interdisciplinary approach to text and culture and bringing forward the cultural productions and expertise of Asian/Americans during this midcentury period. Because I am suggesting the work of Asian/Americans be read alongside other canonical Beat texts, their work destabilizes or “ruins” Beat literature, which has been seen as a body of texts that articulate a political, anticapitalist critique of post-WWII and Cold War-era America, but which I show to be reflective of a specific, European American identity grounded in a politics that does not accommodate the effects of settler colonialism and imperialism. The seeming stability and coherence of the category of “Beat” has only been possible because the work of Asian/Americans in this period was erased, unacknowledged. My project’s major intervention may be found in its combination of critique—where I show how whiteness influenced Euro Americans’ artistic choices and cultural appropriations—and recovery, where I reveal from whom and how these appropriations occurred. Further, I suggest that we begin to analyze American Buddhist writing beyond the limited rubrics formerly available to us in “Beat” and avant-garde literatures and in their communities of reception

    Study, development and improvement of MCM-41-type MSN synthesis oriented to biomedical applications

    Full text link
    [ES] La presente tesis doctoral, titulada "Estudio, desarrollo y mejora de la síntesis de nanopartículas mesoporosas de sílice (MSN) tipo MCM-41 orientada a aplicaciones biomédicas" se centra en la síntesis, caracterización, estudio y evaluación de diferentes MSN tipo MCM-41, con el objetivo de ampliar el conocimiento de las MSN como nanomateriales implicados en aplicaciones biomédicas. El primer capítulo de este trabajo es una introducción general sobre los temas que se van a tratar a lo largo de la tesis. Por un lado, se introducen los principales conceptos sobre las nanopartículas de sílice mesoporosas, y en particular las MSN de tipo MCM-41, como su descubrimiento, sus propiedades, ventajas y aplicaciones, su síntesis y la química implicada, y la posibilidad de ser funcionalizadas o dopadas para adquirir propiedades adicionales y únicas. Por otro lado, se presenta un amplio abanico de técnicas de caracterización de MSN, destacando su importancia en la presente tesis. Por último, se revisan los conceptos de nanomedicina y nanomateriales, incluyendo el conjunto de requisitos que deben cumplir los nanomateriales para ser validados, los tipos de nanomateriales desarrollados hasta el momento y los principales cuellos de botella encontrados en la traslación clínica de los nanomateriales. En este contexto, se revisan los estudios de las MSN en nanomedicina, señalando los retos de las mismas dentro de esta especialidad y la oportunidad que ofrecen a la ciencia de los materiales. En el segundo capítulo se exponen los objetivos generales de la presente tesis doctoral, que son abordados en los siguientes capítulos. El tercer capítulo se basa en un estudio en profundidad del mecanismo de síntesis de las MSN de tipo MCM-41, considerando el mecanismo de estructuración de la sílice, la nucleación, el crecimiento y los procesos de envejecimiento. En particular, se analizan detalladamente las primeras etapas de la síntesis de MSN. Además, se revisan los diferentes modelos descritos sobre el mecanismo de estructuración de la sílice, que han sido ampliamente estudiados. El cuarto capítulo se centra en la investigación del efecto de algunos parámetros tradicionalmente poco estudiados en la síntesis y formación de MSN de tipo MCM-41, como el tiempo de síntesis, la velocidad de agitación, el núcleo de agitación magnética utilizado, la velocidad de adición del TEOS y el método de neutralización una vez formadas las nanopartículas. También se introduce una revisión de la influencia de los parámetros de síntesis más estudiados en las MSN tipo MCM-41. El quinto capítulo se basa en el estudio de la obtención, caracterización y manipulación de MSN de tipo MCM-41 coloidales. En primer lugar, se presenta una revisión crítica de los trabajos que informan sobre la obtención de MSN coloidales, correctamente suspendidas o discretas. En segundo lugar, se introduce una metodología para caracterizar la estabilidad coloidal de las MSN. En tercer lugar, se estudia y compara el comportamiento coloidal de diferentes nanopartículas en diferentes condiciones. Y, por último, se desarrolla un marco conceptual y de trabajo sobre los principios que rigen la estabilidad coloidal de las nanopartículas. El sexto capítulo es un estudio exhaustivo de las implicaciones del uso de diferentes procedimientos de eliminación de surfactantes en las MSN de tipo MCM-41, como la calcinación a diferentes temperaturas y la extracción con disolventes. Las propiedades fisicoquímicas de las MSN estudiadas son la eficiencia de eliminación de surfactantes, el grado de condensación de la sílice, la porosidad, la estabilidad coloidal y la reactividad superficial. Además, se comprobó la biocompatibilidad de las nanopartículas en cuanto a su citotoxicidad y su degradación en un entorno fisiológico simulado, para validar su uso en aplicaciones biomédicas. El séptimo capítulo recoge las conclusiones generales de la presente tesis, que resumen las conclusiones obtenidas en cada capítulo.[CA] L'actual tesi doctoral, titulada "Estudi, desenvolupament i millora de la síntesi de nanopartícules mesoporoses de sílice (MSN) de tipus MCM-41 orientada cap a aplicacions biomèdiques" se centra en la síntesi, caracterització, estudi i avaluació de diferents mostres de MSN de tipus MCM-41 amb l'objectiu de millorar el coneixement de les MSN com nanomaterials implicats en aplicacions biomèdiques. El primer capítol d'aquest treball és una introducció general sobre els elements que es tractaran durant tota la tesi. D'una banda, s'introdueixen els conceptes principals sobre les nanopartícules mesoporoses de sílice, i en particular les de tipus MCM-41, com el seu descobriment, les seues propietats, avantatges i aplicacions, la seua síntesi i la química implicada, i la possibilitat de ser funcionalitzades o dopades per adquirir propietats addicionals i úniques. D'altra banda, es presenta una àmplia gamma de tècniques de caracterització de MSN destacant la seua importància en la tesi actual. Finalment, es revisen els conceptes de nanomedicina i nanomaterials, incloent-hi el conjunt de requisits que els nanomaterials han d'aconseguir per ser validats, els tipus de nanomaterials desenvolupats fins ara, i els principals colls d'ampolla trobats en la translació clínica de nanomaterials. En aquest context, es revisen els estudis de les MSN en nanomedicina, assenyalant els seus reptes dins de la nanomedicina i l'oportunitat que ofereixen a la ciència dels materials. El segon capítol exposa els objectius generals de la tesi doctoral actual, que són abordats en els següents capítols. El tercer capítol es basa en un estudi en profunditat del mecanisme de síntesi de les MSN tipus MCM-41, considerant el mecanisme d'estructuració de la sílice, la nucleació, el creixement i els processos de maduració. Particularment, les primeres etapes de la síntesi de MSNs s'analitzen en detall. A més, es revisen els diferents models reportats sobre el mecanisme d'estructuració de sílice, que ja han sigut àmpliament estudiats. El quart capítol es centra en la investigació de l'efecte d'alguns paràmetres tradicionalment menys estudiats en la síntesi i formació de l'MSN de tipus MCM-41, com: el temps de síntesi, la velocitat d'agitació, el nucli d'agitació magnètica utilitzat, la velocitat d'addició de TEOS i el mètode de neutralització una vegada que es formen les nanopartícules. També s'introdueix una revisió de la influència dels paràmetres de síntesi més estudiats en les MSN de tipus MCM-41. El cinqué capítol es basa en l'estudi de l'obtenció, caracterització i manipulació de les MSN de tipus MCM-41 col·loidals. En primer lloc, es presenta una revisió crítica dels treballs que descriuen l'obtenció de MSN col·loidals, correctament suspeses o discretes. En segon lloc, s'introdueix una metodologia per caracteritzar l'estabilitat col·loidal de les MSN. En tercer lloc, s'estudia i compara el comportament col·loidal de diverses nanopartícules en diferents condicions. I finalment, es desenvolupa un marc conceptual i de treball sobre els principis que regeixen l'estabilitat col·loidal de les nanopartícules. El sisé capítol és un estudi exhaustiu de les implicacions de l'ús de diferents procediments d'extracció de surfactants a les MSN de tipus MCM-41, com la calcinació a diferents temperatures i l'extracció de dissolvents. Les propietats fisicoquímiques de les MSN estudiades són l'eficiència d'extracció de surfactant, el grau de condensació de sílice, la mesoporositat, l'estabilitat col·loidal i la reactivitat de la superfície. A més, la biocompatibilitat de les nanopartícules es va provar pel que fa a la seua citotoxicitat i la seua degradació en un entorn fisiològic simulat, per validar el seu ús en aplicacions biomèdiques. El seté capítol recull les conclusions generals de la tesi actual, que resumeix les conclusions obtingudes en cada capítol, però també proporciona noves perspectives i una visió global de la matèria estudiada.[EN] The present PhD thesis, entitled "Study, development and improvement of MCM-41-type mesoporous silica nanoparticles (MSN) synthesis oriented to biomedical applications" is focused on the synthesis, characterisation, study and evaluation of different MCM-41-type MSN samples to improve the knowledge of MSN as nanomaterials involved in biomedical applications. The first chapter of this work is a general introduction about the items that are going to be treated throughout the thesis. On the one hand, the main concepts about the mesoporous silica nanoparticles, and in particular MCM-41-type MSN, are introduced, such as their discovery, their properties, advantages, and applications, their synthesis and the chemistry involved, and the possibility of being functionalised or doped to acquire additional and unique properties. On the other hand, a wide range of MSN characterisation techniques are presented highlighting their importance in the current thesis. Finally, the concepts of nanomedicine and nanomaterials are reviewed, including the set of requirements the nanomaterials must accomplish to be validated, the types of nanomaterials developed thus far, and the main bottlenecks found in clinical translation of nanomaterials. In this context, the studies of MSN in nanomedicine are reviewed, illustrating the challenges of MSN within the nanomedicine and the opportunity their offer to material science. Second chapter exposes the general objectives of present PhD thesis, which are addressed in the following chapters. Third chapter is based on an in-depth study of the synthesis mechanism of MCM-41-type MSN, considering the silica templating mechanism, the nucleation, the growth and the aging processes. Particularly, the early stages of the MSNs synthesis are substantially analysed. In addition, the different models reported about the silica templating mechanism, which are widely studied, are reviewed. Fourth chapter is focused on the investigation of the effect of some disregarded parameters on the synthesis and formation of MCM-41-type MSN, such as synthesis time, stirring rate, the magnetic stir bar used, TEOS addition rate and the neutralisation method once nanoparticles are formed. A review of the influence of the most studied synthesis parameters on MCM-41-type MSN is also introduced. Fifth chapter is based on the study of the obtaining, characterisation and manipulation of colloidal MCM-41-type MSN. First, a critical review of works that report the obtaining of colloidal, well-suspended or discrete MSN is presented. Second, a methodology to characterise the colloidal stability of MSN is introduced. Third, the colloidal behaviour of several nanoparticles under different conditions is studied and compared. And finally, a conceptual and operational framework about the principles governing the colloidal stability of nanoparticles is developed. Sixth chapter is a comprehensive study of the implications of the use of different surfactant removal procedures on standard MCM-41-type MSN, such as calcination at different temperatures and solvent extraction. The physicochemical properties of MSN studied are the surfactant removal efficiency, the silica condensation degree, the mesostructured framework, the colloidal stability and the surface reactivity. Additionally, the biocompatibility of nanoparticles was tested regarding their cytotoxicity and their degradation in a simulated physiological environment, to validate their use in biomedical applications. Finally, seventh chapter gathers the general conclusions of the current thesis, which summarise the conclusions obtained in each chapter, but also provide new perspectives and the big picture of the studied matter.Candela Noguera, V. (2022). Study, development and improvement of MCM-41-type MSN synthesis oriented to biomedical applications [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/182386TESI
    corecore