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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
311

Stimuli-responsive breakable hybrid organic/inorganic silica nanoparticles for biomedical applications / Nanoparticules de silice hybrides cassables et sensibles vis-à-vis de stimulus pour des applications biomédicales

Totovao, Ricardo 17 February 2017 (has links)
Pour pallier le problème d’efficacité de la plupart des médicaments disponibles sur le marché aujourd’hui, lié à des manques de spécificité et de solubilité, notamment dans le cadre du traitement du cancer, la nanomédecine, via les nanoparticules présente une alternative de grande importance. Dans ce domaine, les nanoparticules de silice ont récemment attiré une énorme attention de la part des scientifiques. Cependant, des problèmes d’élimination liés à la solidité du matériau entravent aujourd’hui sa traduction clinique. Afin d’élucider cette problématique, nous présentons, dans cette thèse, l’utilisation de nanoparticules de silice hybrides dont l’une est mésoporeuse et l’autre sous forme de nanocapsule dépourvue de porosité. Les particules qui sont sphériques ont été préparées en incorporant un groupement imine dans leur charpente afin de les rendre sensibles au pH bas, sachant que les tissus cancéreux présentent une certaine acidité par comparaison aux tissus sains. Les matériaux préparés se montrent particulièrement sensibles aux milieux acides similaires aux conditions dans les milieux cancéreux. Dans le même temps, ces particules exposent une bonne stabilité en milieu à pH neutre similaire aux conditions physiologiques. Des études in vitro réalisées avec la particule mésoporeuse sur une lignée de cellule cancéreuse issue du sein humain démontrent une bonne et rapide internalisation. De plus, lorsque le matériau est chargé avec un médicament hydrophobe très puissant utilisé dans le traitement du cancer du sein, le système en résultant indique une efficacité de grande ampleur en tuant une forte majorité des cellules cancéreuses, contrairement au système basé sur la particule non cassable et au médicament isolé. Parallèlement, les nanocapsules chargées avec un autre agent anticancéreux se montrent particulièrement cytotoxiques vis-à-vis de cellules cancéreuses très communes et qui l’internalisent de manière très rapide. / To overcome the limitations of most of the drugs avaible nowadays on the market due to their lack of solubility and specifity in cancer treatment for instance, nanomedicine plays an emerging role as an alternative. In that field, nanoparticles are endowed with several advantages, leading them to be highly considered for drug delivery systems preparation. In this respect, silica nanoparticles have recently a great deal of attention from the scientists. Nevertheless, some issues related to the in vivo elimination of silica materials represent the main obstacle impeding their clinical translation. To elucidate this problematic, we report, in this thesis, the use of breakable hybrid organosilica nanoparticles where one is mesoporous and the other one consists in a nanocapsule without porosity. Such materials have been prepared by incorporating an imine-based linker in the particles framework in order to make them pH-responsive. The advantage of the pH sensitivity relies on the fact that cancerous media present certain acidity as compared to those healthy. The particles exhibit a high pH sensitivity where, at low pH, they fully break down, while a good stability is observed in physiological conditions. Furthermore, in vitro studies performed with a drug delivery system based on the mesoporous particle and a highly hydrophobic drug show a remarkable efficiency towards a cancer cell line from human breast, which moreover, rapidly internalises the material. The nanocapsule loaded with a hydrophilic drug also demonstrates a fast internalisation towards a commonly used cancer line which does not resist to the system and thus dies by a very high rate.
312

An Exploration of Office Design: Understanding the character of our workplaces

De Klerk, Sunica 09 December 2013 (has links)
The workplace environment is intrinsically dynamic, yet architecturally it is treated as something that is fixed. Functional layouts specific to the thinking of the time (zeitgeist) are built into the structure leaving little opportunity for adaptation. Frank Lloyd Wright’s Johnson Wax building is one such example; built to function in the Taylorist paradigm with little scope for alteration. The contemporary workplace often lends itself to the adaptive reuse of a range of building typologies or the construction of new structures with Green Star ratings. At the same time, a significant amount of office buildings, constructed prior to the green building movement of the 1990’s, are still in use, despite the typically hermetic and unhealthy spaces they contain. The possibility of adapting an office building from pre-1990 building stock is investigated. Previous workplace layouts inhibited conversation (since interaction in the workplace was frowned upon), but today workplaces are designed with social interaction as its core. The largely unused potential of this aspect within corporate culture and the influence it might have on spatial organisations is investigated. Interior architecture, as mediator between office buildings’ accommodation and their dynamic programs, forms the premise of the study. The hypothesis that an interior architectural intervention can make a positive translation from an unhealthy to a healthy building is tested by designing for the interplay between the character of a space and its design elements. The design process is guided by the Open Building methodology of fixed, semi-fixed and loose-fit. The intervention translates this methodology into a responsive and context conscious proposal with an emphasis on the users and their sense of place. Finally, traditional architectural elements are reinterpreted in terms of their ability to enable or disable interaction between users according to the theory of social friction. Three types of interaction are considered: official meetings, casual meetings and chance encounters. Human interaction, central to the creation of a workplace as opposed to a work space, is a constant theme throughout the study. / Dissertation MInt(Prof)--University of Pretoria, 2013 / Architecture / MInt(Prof) / Unrestricted
313

Manufacturing Microfluidic Flow Focusing Devices For Stimuli Responsive Alginate Microsphere Generation And Cell Encapsulation

Karasinski, Michael A. 01 January 2017 (has links)
In this paper a novel stimuli responsive hydrogel material, methacrylated sodium alginate beta-cyclodextrin (Alg-MA-β-CD), was used in combination with a microfluidic device to create microspheres. Currently there is no reliable method for fabricating homogeneous stimuli-responsive microspheres, in-house microfluidic devices are not reliable in manufacture quality or long-term use. Alginate hydrogels have many attractive characteristics for bioengineering applications and are commonly used to mimic the features and properties of the extracellular matrix (ECM). Human mesenchymal stem cells (hMSCs) are of top interest to tissue engineers. hMSCs are widely available and can be harvested and cultured directly out of human bone marrow. hMSCs have the ability to differentiate into osteoblasts, adipocytes, chondrocytes, muscle cells, and stromal fibroblasts depending on mechanical signals transmitted through surrounding ECM. The biomechanical properties of alginate based stimuli-responsive hydrogels can be tuned to match those of different types of tissues. When trying to transport and control the differentiation of hMSCs into generating new tissues or regenerating damaged tissues, it is highly beneficial to encapsulate the cells inside a microsphere made from these hydrogels. The proposed research objectives are: 1) To optimize fabrication techniques and create functional microfluidic devices; 2) Analyze the effects of flow parameters on microsphere production; and 3) Encapsulate viable hMSCs inside multi-stimuli responsive alginate microspheres using the fabricated microfluidic devices (MFDs). In this study, photolithography microfabrication methods were used to create flow-focusing style MFDs. The hydrogel materials were characterized via rheological methods. Syringe pumps controlled flow rates of fluids through the devices. Active droplets formation was monitored through a camera attached to an inverted microscope, where images were analyzed. Microsphere production was analyzed optically and characterized. Alg-MA-β-CD polymer solutions containing hMSCs were encapsulated, and a live/dead florescence assay was preformed to verify cell viability. Using a modified fabrication process it was possible to manufacture Alg-MA-β-CD microspheres and encapsulate and maintain viable hMSCs inside.
314

Using Culturally Responsive Teaching with Culturally and Linguistically Diverse Students with Specific Learning Disabilities to Increase Performance in Algebra I

Munoz, Lorena R 26 October 2016 (has links)
As the United States (U.S.) population continues to change and become racially/ethnically, culturally, linguistically, and economically diverse, so does the population in public schools (Institute of Education Sciences, 2010). Additionally, the number of culturally and linguistically diverse (CLD) students has been overrepresented in the subgroup of students with learning disabilities (SLD) (Artiles & Ortiz, 2002; Kalynpur & Harry, 2012; Klingner & Harry, 2014). Therefore, there is a need to adapt the curriculum and pedagogy to teach the growing number of diverse students in public schools. The results of national assessments show that students of color have lagged behind their White counterparts in mathematics achievement over the years (Cortes, Goodman, & Nomi, 2013). Despite the push to remediate this problem, teachers continue to use ineffective teacher-led practices and the achievement gap persists across public schools (Williams, 2011). The use of cultural responsive teaching (CRT) among CLD students is promising (Santamaria, 2009). However, there is need to investigate the use of these practices in Algebra I courses with CLD students with SLD. The present 17-week pre-post study compared student achievement in Algebra I courses between two groups of CLD students with SLD (N=63). These groups were (a) 31 students who received CRT (treatment group) by teachers who received CRT training and (b) 32 students who received instruction by teachers who did not receive CRT training (control group). There are significant differences between the treatment and the control group on the CLD students with SLD Algebra I Mid-Year Assessment (MYA) and the students’ Mathematics Self-Efficacy scores (MSES). The teachers’ level of cultural consciousness had an insignificant covariance on the Algebra I MYA, yet the teachers’ observations and their cultural responsive self-assessment had a direct effect on the Algebra I MYA. Additionally, there was not significant interaction between MSES and TCS on the students’ Algebra I MYA. The results of the study suggest that the use of CRT is a promising practice to improve CLD students’ with SLD Algebra I achievement and perhaps close the math achievement gap.
315

Design & Fabrication of Bio-responsive Drug Carriers Based on Protamine & Chondroitin Sulphate Biopolymers

Radhakrishnan, Krishna January 2014 (has links) (PDF)
The present thesis focuses on the fabrication of bio-stimuli responsive micro- and nano-carriers for drug delivery applications. In particular, the objective of this work is to investigate the possibility of using polypeptide drug protamine and glycosaminoglycan drug, chondroitin sulphate as stimuli responsive components in the design of bioresponsive carriers. These biopolymers are biocompatible, biodegradable and clinically used for various applications. Two designs that incorporate these stimuli responsive components have been studied in this thesis. The first design involves hollow micro and nanocapsules that have been fabricated by incorporating the stimuli responsive biopolymers as wall components. Upon exposure to biological triggers, these hollow capsules disintegrate releasing the encapsulated drug. The second design consists of mesoporous silica nanoparticles-biopolymer hybrids. The mesoporous silica nanoparticles act as a gated scaffold that carries the drug molecules. The mesopores of these drug loaded nanoparticles are then blocked with the bioresponsive polymers. Upon exposure to the bio-triggers which consist of enzymes over-expressed in conditions such as cancer and inflammation, these “molecular gates” disintegrate allowing the drug trapped in the mesoporous silica nanoparticles to escape into the surroundings. The thesis has been divided into five chapters: Chapter 1 is an introduction to bio-responsive drug delivery. The broad classification of stimuli used in responsive drug delivery systems are visited. A brief discussion on the various types of bio-stimuli that can be utilized in designing bio-responsive systems is also included in this chapter. Chapter 2 defines the aims and scope of the thesis which is followed by an overview of the various design parameters involved in the fabrication of systems presented in this work. The major stimuli responsive components and the architectures incorporating these elements are discussed in detail here. A literature review of the various carrier designs involved in the study is provided , with special emphasis on stimuli responsive drug delivery. Chapter 3 gives an overview of the various materials and methods involved in this work. A summary of the various characterisation techniques used in the thesis is also included along with the details of the experiments that has been carried out. Chapter 4 provides an overview of the results and discussions of the thesis. The chapter has been divided into six sections: Chapter 4.1 deals with the fabrication of a hollow microcapsule system incorporated with protamine as the stimuli responsive element for bio-responsive drug delivery. The hollow microcapsules that were fabricated by Layer by Layer assembly of protamine and heparin display pH responsive variations in permeability and disintegrate in the presence of the enzyme trypsin that degrades protamine. The biologically triggered enzyme responsive drug release from these microcapsules is also demonstrated using enzymes secreted by colorectal cancer cells. Chapter 4.2 presents nanocapsules fabricated from protamine and heparin. The pH and enzyme responsive drug release of this systems is evaluated in vitro. A wall crosslinking strategy has been tested to control the rate of drug release under physiological pH conditions in the absence of the trigger. The cellular interactions of these nanocapsules loaded with an anticancer drug, doxorubicin was studied using cancer cell lines. Bioavailability studies of doxorubicin encapsulated in these nanocapsules were performed using a BALB/c mice model. Chapter 4.3 discusses the fabrication of a hollow microcapsule system that can disintegrate in response to dual biological stimuli. These carriers have been fabricated by incorporating protamine and chondroitin sulphate as the wall components. Due to the incorporation of two separate stimuli responsive components in the walls, these capsules are expected to be sensitive to the enzymes trypsin or hyaluronidase I. Chapter 4.4 deals with the fabrication of dual enzyme responsive hollow nanocapsule which can be targeted to deliver anticancer agents specifically inside cancer cells. The enzyme responsive elements integrated in the hollow nanocapsule walls can undergo degradation in presence of either of the enzymes trypsin or hyaluronidase I leading to the release of encapsulated drug molecules. The drug release from these nanocapsules which were crosslinked and functionalised with folic acid, is evaluated under varying conditions. The cellular uptake and intracellular drug delivery by these nanocapsules were evaluated in cervical cancer cell lines. Chapter 4.5 introduces a mesoporous silica nanoparticle − protamine hybrid system. The system consists of a mesoporous silica nanoparticle support whose mesopores are capped with protamine which effectively blocks the outward diffusion of the drug molecules from the mesopores of the mesoporous silica nanoparticles. Upon exposure to the enzyme trigger, the protamine cap disintegrates opening up the molecular gates and releasing the entrapped drug molecules. The drug release from this system is evaluated in different release conditions in the presence and absence of the enzyme trigger. The ability of these particles to deliver hydrophobic anticancer drugs and induce cell death in colorectal cancer cells has also been demonstrated. Chapter 4.6 discusses the fabrication of another mesoporous silica nanoparticles based bio-responsive drug delivery system consisting of mesoporous silica and chondroitin sulphate hybrid nanoparticles. The ability of the system to modulate drug release in response to hyaluronidase I is demonstrated. By utilizing a cervical cancer cell line, we have demonstrated the cellular uptake and intracellular delivery of hydrophobic drugs encapsulated in these particles. Interestingly, the system showed ability to enhance the anticancer activity of hydrophobic drug curcumin in these cancer cells. Chapter 5 gives a summary of the general conclusions drawn from the thesis work.
316

Fiddling with a Culturally Responsive Curriculum

Gluska, Virginia January 2011 (has links)
The discourse on education for Aboriginal people has long been limited to a curriculum of cultural assimilation often resulting in an erosion of self-esteem and disengagement. Consequently, this research puts forth narratives of how fiddle programs in northern Manitoba work as a culturally responsive curriculum that in turn address such curricular erosions. As a research methodology, Metissage afforded me pedagogical opportunities to weave the various perspectives of community members, parents, instructors, and former students into an intricate story that attempts to represent some of their social, cultural and historical experiences within the north. Braiding stories of the historical and present impacts of fiddle playing reveals the generative possibilities of school fiddle programs in Canadian Indigenous communities. In addition to building intergenerational bridges, the stories put forth in this thesis demonstrate how the fiddle has become a contemporary instrument of social change for many communities across northern Manitoba.
317

Aplikace SEO technik pro marketing / Application of SEO for marketing

Knapovský, Martin January 2016 (has links)
The aim of this thesis is to describe in detail the current ways of optimizing websites for search engines (SEO) and to apply them in a broader marketing strategy of italian restaurant La Casa Degli Amici. The thesis presents evidence about the importance of SEO for marketing and can be used as a template for optimizing you own website. This thesis is divided into two main parts - theoretical and practical. The theoretical part explains the concepts used in the design and implementation of the practical part. The theoretical part considers 3 main subjects - search engine, users and SEO which represents website creation and optimization. This thesis describes the history of search engines and the way search engines analyze and evaluate a website. It also describes user search strategies and the way users read the search results. In the SEO section we show its advantages, brief history, SEO strategies and description of techniques and tools that can be used for SEO. In the practical part we put together a marketing strategy which consists of website creation, implementation of selected SEO techniques and social network marketing. Implementation of the marketing strategy is evaluated on data obtained during the period between 1. 8. 2016 and 31. 11. 2016. Owner of the restaurant has provided data on sales which were used for overall evaluation of implemented marketing strategy.
318

Responzivní webdesign / Responsive webdesign

Hnízdil, Jakub January 2014 (has links)
This Master thesis focuses on responsive web design. The main objective is to provide comprehensive view of the website created in so-called responsive realization, and impart awareness to readers not only about idea of responsive web design itself, but also about other ways of creating mobile webs. Furthermore, thesis deals with constructing of overview and comparison of selected technologies and frameworks with support of creating responsive websites. Every group of technologies or procedures is discussed in single chapter, to let reader simple and clearly return to particular concepts. After reading this thesis the reader should acquire not only detailed knowledge about responsive web design, but also suggestions and manuals for creating websites and for decisions in choosing the type of technology, which is possible to use to creating websites.
319

A study of particle structure and film formation mechanism on the mechanical properties of synthetic rubber films

Tungchaiwattana, Somjit January 2014 (has links)
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.
320

Responsive hydrogels using self-assembling polymer-peptide conjugates

Maslovskis, Antons January 2010 (has links)
Stimuli-responsive polymers and self-assembling peptides represent two classes of materials with interesting properties and great potential to be used as biomaterials. The conjugation of polymer with peptide offers a way to combine the controlled chemical, mechanical, and thermal properties of polymer with the functionality of designed bioactive group. Pure hybrid materials with the characteristics of individual components or systems containing hybrid materials became attractive for applications in drug delivery and tissue engineering. This work focused on systems where the thermo-responsive properties of a polymer were combined with the gelling properties of two different ionic-complementary peptides via conjugation. The prototypical thermo-responsive polymer poly(N-isopropylacrylamide) (PNIPAAm) was chosen due to its lower critical solution temperature (LCST) ~32°C being close to body temperature. Ionic-complementary oligo-peptides, containing the alternating hydrophobic/hydrophilic and charged/uncharged amino acids, phenylalanine (F), glutamic acid (E) and lysine (K), were selected as they are known to form β-sheet rich fibrillar networks at low concentrations. Two peptide sequences with different charge distribution were chosen: FEFEFKFK and FEFKFEFK which form self-supporting gels at ~17 and 10 mg ml-1 respectively. Polymer-peptide conjugates were used to confer self-assembling and thermo-responsive behaviour to the system.Thermo-responsive PNIPAAm-rich hydrogels were obtained by targeting different degrees of functionalisation of PNIPAAm with the self-assembling peptides. Two series of such systems were prepared by using either a thiol-modified FEFEFKFK or a thiol-modified FEFKFEFK peptide as the chain-transfer agent in the free radical polymerisation of NIPAAm. The resulting polymer/conjugate mixtures were studied by proton nuclear magnetic resonance (1H NMR). The polymer/conjugate ratios were calculated and showed that the conjugate fraction in the mixtures increased with increasing concentration of peptide used for the polymerisation. Static light scattering (SLS) and viscometry showed the aggregation of the polymer/conjugate mixtures presumably due to the presence of peptide. The values from gel permeation chromatography (GPC), which were mostly attributed to the unconjugated polymers, were higher than those obtained from 1H NMR and centrifugation for the conjugates. The polymer/conjugate mixtures formed self-supporting gels where the critical gelation concentration decreased with increasing conjugate content. Oscillatory rheology experiments confirmed gels had formed and revealed that their elastic modulus, G' varied from ~ 10 to 400 Pa depending on the sample. TEM and AFM studies proved the formation of β-sheet fibres of ~ 4.5 ± 1.5 nm in diameter. The PNIPAAm-rich hydrogels were also characterised by micro DSC to reveal their thermo-responsiveness and phase separation and showed the LCST at ~ 30°C. The results of the study showed that varying the peptide sequence did not have an effect on thermal, mechanical or morphological properties of the hydrogels. By exploiting the self-assembly of the ionic-complementary peptides, it was possible to create PNIPAAm-rich, thermo-responsive hydrogels with controllable properties.Further in the study pure PNIPAAm-FEFEFKFK conjugate was incorporated into the FEFEFKFK peptide matrix to create peptide-rich thermo-responsive composite gels. Two series of the composite gels were prepared by varying separately the peptide matrix and polymer-peptide conjugate concentration. Micro DSC measurements revealed an endothermic peak at ~ 30ºC characteristic of the LCST of PNIPAAm. Oscillatory rheology studies showed that the composite gels became stronger with increasing conjugate concentration (G' ~ 20 - 200 Pa). Network morphology was studied by SANS. Using contrast variation and contrast matching techniques it was possible to distinguish between the peptide fibres and the PNIPAAm chains. Below and above the LCST the scattering curves showed a q-1 behaviour which is typical of rod-like objects. TEM and AFM also proved the formation of fibres of ~4.0 ± 0.8 nm and ~4.5 ± 1 nm respectively. AFM studies showed that the fibres of the composite gels were decorated with polymer chains. The thermo-responsiveness and the gelation properties of these conjugate-based scaffolds have potential for use as drug delivery vehicles or tissue engineering scaffolds.

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