Tesi: "Bioengineering"

7

Crowther, Damian C. "The bioengineering of targeted serpins." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260598.

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8

Busuttil, Naudi Kurt. "Bone bioengineering for mandibular reconstruction." Thesis, University of Glasgow, 2011. http://theses.gla.ac.uk/2419/.

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Abstract (sommario):

The reconstruction of critical-size bone defects following tumour resection or bone loss due to trauma is topical today and relates to the complexity of the treatment involved and poor healing outcomes. In bone bioengineering, the current trends are to explore novel methods of repairing these defects by using various bone substitutes. Various graft materials have been used for the restoration of these defects. A graft ideally needs to promote osteogenesis, osteoinduction and osteoconduction. The aim of this investigation was to assess the histological, radiographic and mechanical properties of the tissue regenerate following the application of tricalcium phosphate (TCP) scaffolding and recombinant human bone morphogenetic protein 7 (rhBMP-7) for the reconstruction of a critical-size osteoperiosteal mandibular continuity defect in the rabbit model. Highly purified and freeze dried recombinant human BMP-7 was used. It was produced by Chinese hamster ovary cells in culture and purified from the culture media. All the TCP samples had a porosity of 80% and average pore size of 100 – 500µm. For the rhBMP-7 loaded scaffolds; rhBMP-7 was reconstituted according to a recommended specification and 400ng were loaded by adsorption into the TCP scaffolds. Nine adult New Zealand white rabbits (3.0-4.0kg) were used for the planned study. In each case a unilateral osteoperiosteal mandibular body critical-size defect was created. In six cases the critical-size defect was filled with the rhBMP-7 on the TCP scaffolding, and in three cases the TCP was used alone. Assessments were made with plain radiographs at 0, 4, 8, and 12 weeks follow-up. Three months post-operatively the animals were sacrificed, the mandibles removed and the surgical sites were assessed with cone beam CT radiography, tested mechanically and analysed histologically. More bone regeneration was seen radiographically and histologically within the mandibles that received rhBMP-7 in the TCP, with evidence of both woven and lamellar bone formation. Union was obtained at the surgical site with no cartilage formation. The regenerated bone was confined to the area that had received the scaffold, with no calcification of the surrounding soft tissues. The TCP was also resorbed more completely in this experimental group. Very little bone was formed in the cases where the defect was filled with TCP alone. The mechanical properties of the regenerate in the group that received the rhBMP-7 and TCP were also significantly superior to those of the cases that received TCP alone. Histologically the overall mean of the percentage regenerated bone volume in the rhBMP-7 and TCP cases was 29.41% ± 6.25, while that for the TCP alone cases was 6.35% ± 3.08. The difference between the groups was statistically significant (p = 0.014). Mechanically the failure moments for the TCP alone cases were found to be very low (0-48mNm) while those for the rhBMP-7 and TCP cases were higher but there was considerable variation between the cases (55-2115mNm). Some of the cases in this group achieved failure moments comparable to normal untreated bone. In conclusion TCP scaffolding and rhBMP-7 can be used successfully for the reconstruction of critical-size mandibular defects in the rabbit model and TCP loaded with rhBMP-7 was significantly superior in its capacity for bone regeneration histologically when compared to TCP alone. The resultant bony regenerate could also at times have mechanical properties similar to those of natural bone. But due to the variability of the mechanical properties further investigations are required before clinical application.

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9

ANGELATS, LOBO DAVID. "DEVELOPMENT OF ALTERNATIVE BIOENGINEERING STRATEGIES." Doctoral thesis, Università degli studi di Brescia, 2022. http://hdl.handle.net/11379/560219.

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Concettualmente, la produzione additiva permette la rapida e precisa produzione delle parti complesse. La produzione additiva richiede di un disegno previo della parte da fabbricare per un software di progettazione assistita da computer (CAD, in inglese). A causa delle limitazioni del CAD software, particolarmente nelle curve, alcune delle parti stampate esige trattamenti aggiuntivi o di post lavorazione per ottenere la morfologia e la struttura desiderate. La produzione additiva e la stampa tridimensionale (3D) erano solo stabiliti nella area di ingegneria. Nell 21⁰ secolo, la idea di usare le tecnologie di stampa tridimensionale per sviluppare delle strutture tridimensionale per il sostegno della coltura cellulare e de imitare il microambiente nativo, avanza una nuova area chiamata Biostampa. Nella biostampa, diverse technologie possono essere usate, essendo la stampa per estrusione la più versatile e consolidata. Le stampanti 3D come la 3D-Bioplotter™ usano un nuovo metodo, la biostampa diretta, che permette la stampa di una struttura integrata con le cellule che assomiglia le condizioni in vivo. Allo stesso modo, diverse aree di recerca possono trarne beneficio della biostampa 3D, come lo studio di disturbi o malattie ad esempio il cancro. Per definizione, il cancro è una malattia eterogenea che provoca 10 milioni di morti nel mondo all’anno, essendo il carcinoma mammario la seconda causa di morte tra le donne negli Stati Uniti e Europa. Il carcinoma mammario triplo negativo (TNBC, in inglese) è stato descrito come un sottotipo molto aggressivo, però la mancanza di conoscenza di come inicia il processo tumorale rende il suo studio molto interesante. La combinazione di fibre elettrofilate e una linea cellulare del carcinoma mammario triplo negativo (MDA-MB-231), dimostra la formazione di aggregati cellulari simil-tumorali. Potrrebe esse usati nella medicina personalizata del cancro, selezionando il migliore trattamento per ogni paziente nel futuro. Conceptually, additive manufacturing allows rapid and precise manufacturing of complex parts. Additive manufacturing requires a previous design of the piece to be fabricated by computer-aided design (CAD) software. Due to the limitations of CAD software, especially on curves, some of the printed pieces require additional or post-processing treatments to achieve the desired morphology and structure. Additive manufacturing and three-dimensional (3D) printed were both previously established only in the engineering field. In the 21st century, the idea of using 3D printing technologies to develop 3D structures to support cell culture and mimic native cellular microenvironment, push forward a new field in research called Bioprinting. In bioprinting, several technologies can be used, being extrusion printing the more versatile and well established. 3D printers like the 3D-Bioplotter™ use a new method, direct bioprinting, which permits the printing of a structure integrated with cells that resembles more to the in vivo conditions. Likewise, different research areas can benefit from 3D Bioprinting, like the study of disorders or diseases such as cancer. By definition, cancer is a heterogenic disorder that causes 10 million deaths worldwide, being breast cancer the second cause of death among women in the USA and Europe. Triple-negative breast cancer (TNBC) has been described as the most aggressive subtype, but the lack of knowledge on how the tumoral process begins makes its study more interesting. Combining electrospun fibers and a triple-negative breast cancer cell line (MDA-MB-231) demonstrates the formation of tumor-like cell aggregates. It might be used in personalized medicine of cancer by selecting the best treatment for each patient in the future.

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10

ANGELATS, LOBO DAVID. "DEVELOPMENT OF ALTERNATIVE BIOENGINEERING STRATEGIES." Doctoral thesis, Università degli studi di Brescia, 2022. http://hdl.handle.net/11379/560196.

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Abstract (sommario):

Concettualmente, la produzione additiva permette la rapida e precisa produzione delle parti complesse. La produzione additiva richiede di un disegno previo della parte da fabbricare per un software di progettazione assistita da computer (CAD, in inglese). A causa delle limitazioni del CAD software, particolarmente nelle curve, alcune delle parti stampate esige trattamenti aggiuntivi o di post lavorazione per ottenere la morfologia e la struttura desiderate. La produzione additiva e la stampa tridimensionale (3D) erano solo stabiliti nella area di ingegneria. Nell 21⁰ secolo, la idea di usare le tecnologie di stampa tridimensionale per sviluppare delle strutture tridimensionale per il sostegno della coltura cellulare e de imitare il microambiente nativo, avanza una nuova area chiamata Biostampa. Nella biostampa, diverse technologie possono essere usate, essendo la stampa per estrusione la più versatile e consolidata. Le stampanti 3D come la 3D-Bioplotter™ usano un nuovo metodo, la biostampa diretta, che permette la stampa di una struttura integrata con le cellule che assomiglia le condizioni in vivo. Allo stesso modo, diverse aree di recerca possono trarne beneficio della biostampa 3D, come lo studio di disturbi o malattie ad esempio il cancro. Per definizione, il cancro è una malattia eterogenea che provoca 10 milioni di morti nel mondo all’anno, essendo il carcinoma mammario la seconda causa di morte tra le donne negli Stati Uniti e Europa. Il carcinoma mammario triplo negativo (TNBC, in inglese) è stato descrito come un sottotipo molto aggressivo, però la mancanza di conoscenza di come inicia il processo tumorale rende il suo studio molto interesante. La combinazione di fibre elettrofilate e una linea cellulare del carcinoma mammario triplo negativo (MDA-MB-231), dimostra la formazione di aggregati cellulari simil-tumorali. Potrrebe esse usati nella medicina personalizata del cancro, selezionando il migliore trattamento per ogni paziente nel futuro. Conceptually, additive manufacturing allows rapid and precise manufacturing of complex parts. Additive manufacturing requires a previous design of the piece to be fabricated by computer-aided design (CAD) software. Due to the limitations of CAD software, especially on curves, some of the printed pieces require additional or post-processing treatments to achieve the desired morphology and structure. Additive manufacturing and three-dimensional (3D) printed were both previously established only in the engineering field. In the 21st century, the idea of using 3D printing technologies to develop 3D structures to support cell culture and mimic native cellular microenvironment, push forward a new field in research called Bioprinting. In bioprinting, several technologies can be used, being extrusion printing the more versatile and well established. 3D printers like the 3D-Bioplotter™ use a new method, direct bioprinting, which permits the printing of a structure integrated with cells that resembles more to the in vivo conditions. Likewise, different research areas can benefit from 3D Bioprinting, like the study of disorders or diseases such as cancer. By definition, cancer is a heterogenic disorder that causes 10 million deaths worldwide, being breast cancer the second cause of death among women in the USA and Europe. Triple-negative breast cancer (TNBC) has been described as the most aggressive subtype, but the lack of knowledge on how the tumoral process begins makes its study more interesting. Combining electrospun fibers and a triple-negative breast cancer cell line (MDA-MB-231) demonstrates the formation of tumor-like cell aggregates. It might be used in personalized medicine of cancer by selecting the best treatment for each patient in the future.

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11

ANGELATS, LOBO DAVID. "DEVELOPMENT OF ALTERNATIVE BIOENGINEERING STRATEGIES." Doctoral thesis, Università degli studi di Brescia, 2022. http://hdl.handle.net/11379/560216.

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Abstract (sommario):

Concettualmente, la produzione additiva permette la rapida e precisa produzione delle parti complesse. La produzione additiva richiede di un disegno previo della parte da fabbricare per un software di progettazione assistita da computer (CAD, in inglese). A causa delle limitazioni del CAD software, particolarmente nelle curve, alcune delle parti stampate esige trattamenti aggiuntivi o di post lavorazione per ottenere la morfologia e la struttura desiderate. La produzione additiva e la stampa tridimensionale (3D) erano solo stabiliti nella area di ingegneria. Nell 21⁰ secolo, la idea di usare le tecnologie di stampa tridimensionale per sviluppare delle strutture tridimensionale per il sostegno della coltura cellulare e de imitare il microambiente nativo, avanza una nuova area chiamata Biostampa. Nella biostampa, diverse technologie possono essere usate, essendo la stampa per estrusione la più versatile e consolidata. Le stampanti 3D come la 3D-Bioplotter™ usano un nuovo metodo, la biostampa diretta, che permette la stampa di una struttura integrata con le cellule che assomiglia le condizioni in vivo. Allo stesso modo, diverse aree di recerca possono trarne beneficio della biostampa 3D, come lo studio di disturbi o malattie ad esempio il cancro. Per definizione, il cancro è una malattia eterogenea che provoca 10 milioni di morti nel mondo all’anno, essendo il carcinoma mammario la seconda causa di morte tra le donne negli Stati Uniti e Europa. Il carcinoma mammario triplo negativo (TNBC, in inglese) è stato descrito come un sottotipo molto aggressivo, però la mancanza di conoscenza di come inicia il processo tumorale rende il suo studio molto interesante. La combinazione di fibre elettrofilate e una linea cellulare del carcinoma mammario triplo negativo (MDA-MB-231), dimostra la formazione di aggregati cellulari simil-tumorali. Potrrebe esse usati nella medicina personalizata del cancro, selezionando il migliore trattamento per ogni paziente nel futuro. Conceptually, additive manufacturing allows rapid and precise manufacturing of complex parts. Additive manufacturing requires a previous design of the piece to be fabricated by computer-aided design (CAD) software. Due to the limitations of CAD software, especially on curves, some of the printed pieces require additional or post-processing treatments to achieve the desired morphology and structure. Additive manufacturing and three-dimensional (3D) printed were both previously established only in the engineering field. In the 21st century, the idea of using 3D printing technologies to develop 3D structures to support cell culture and mimic native cellular microenvironment, push forward a new field in research called Bioprinting. In bioprinting, several technologies can be used, being extrusion printing the more versatile and well established. 3D printers like the 3D-Bioplotter™ use a new method, direct bioprinting, which permits the printing of a structure integrated with cells that resembles more to the in vivo conditions. Likewise, different research areas can benefit from 3D Bioprinting, like the study of disorders or diseases such as cancer. By definition, cancer is a heterogenic disorder that causes 10 million deaths worldwide, being breast cancer the second cause of death among women in the USA and Europe. Triple-negative breast cancer (TNBC) has been described as the most aggressive subtype, but the lack of knowledge on how the tumoral process begins makes its study more interesting. Combining electrospun fibers and a triple-negative breast cancer cell line (MDA-MB-231) demonstrates the formation of tumor-like cell aggregates. It might be used in personalized medicine of cancer by selecting the best treatment for each patient in the future.

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12

Kuo, Cheng-Hwa. "Bioengineering scaffolds for cell migration assay." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.707983.

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13

Forest, Fabien. "Bioengineering de greffons endothéliaux : versant cellulaire." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSES067.

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La cécité d’origine cornéenne est Ia deuxième cause de cécité dans le monde. Son traitement de choix est la kératoplastie. ll est aujourd’hui nécessaire de réfléchir à de nouvelles solutions pour remplacer la kératoplastie dans sa forme actuelle qui bien que satisfaisante, n’est pas totalement parfaite. En effet, les techniques actuelles de kératoplastie utilisent une allogreffe. Le greffon va subir chez le donneur une diminution de la densité des cellules endothéliales (CE) du greffon au fil du temps. Ce travail présente successivement les solutions abordées par le BiiGC pour produire des CE en masse ainsi que les différents supports en vue d’une kératoplastie lamellaire postérieure. Les solutions envisagées par le laboratoire BiiGC doivent permettre un transfert à l’être humain dans des conditions de sécurité et d’acceptabilité maximales. Les différents contrôles de l’identité des cellules obtenues et les contrôles de sécurité nécessitent une connaissance robuste de la biologie, du morphotype et du phénotype des CE cornéennes. Cette thèse présente les différentes exigences réglementaires et de qualité nécessaires à l’obtention de greffons cornéens bioengineerés. Le choix du BiiGC devant se conformer d’emblée à ces exigences en vue d’un transfert à l’être humain. Dans une première partie, nous présentons une revue de la littérature sur le bioengineering de greffons cornéens. La production de CE et de stroma seront ensuite exposés avec les différentes approches abordées par le BiiGC. Enfin, les différentes techniques de validation morphologiques et fonctionnelles de greffons obtenus seront présentées Corneal diseases are the first leading cause of blindness worldwide. Its treatment relies on keratoplasty which in its actual form is a satisfying but not a perfect solution. We have to think about new solutions for corneal graft. Today, corneal graft is often an allograft. With this technique, there is a loss of endothelial cell (EC) density through time. This work presents the solutions which BiiGC laboratory is working on for mass production of EC and different carriers for these cells for posterior keratoplasty. These solutions must be possible on human being with safety conditions. Controls of identity, of obtained cells and security controls need a strong knowledge of biology, morphology and phenotype of EC. This work presents the legal conditions of quality needed to obtain bioengineered corneal grafts. The choice of BiiGC laboratory must involve these conditions for a transfer to human being. In a first part, we present a review of the literature about corneal bioengineering. Production of EC and of corneal stroma are discussed with different approaches by BiiGC laboratory. In the end, the different techniques of morphological controls of corneal grafts are discussed

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14

Browning, Alexander P. "Model complexity in biology and bioengineering." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/227787/1/Alexander_Browning_Thesis.pdf.

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In biology and bioengineering, mathematical and statistical analysis provides an understanding of biological systems that enables their control and manipulation. Tailoring mathematical and experimental complexity to the biological question of interest is crucial to avoid issues relating to parameter identifiability. We develop models and tools to bring new data-based insights to a range of contemporary problems in biology and bioengineering. These include data-focused stochastic models that describe complex cell interactions and decision making, incorporating biological systems into new engineered materials, and new tools to diagnose parameter identifiability and guide model complexity for stochastic differential equation models.

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15

Pescador, Álvarez Paula. "Colloidal and molecular assemblies for bioengineering applications." Doctoral thesis, Universitat Rovira i Virgili, 2007. http://hdl.handle.net/10803/8557.

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La técnica de recubrimiento "capa por capa' (layer-by-layer, LbL) de superficies cargadas mediante materiales con carga opuesta es una herramienta versátil para la fabricación de ensamblados moleculares e interfaces funcionales. Sus principales ventajas sobre otras metodologías, como las monocapas autoensambladas (SAM) o la técnica de Langmuir-Blodgett, son una enorme flexibilidad combinada con su gran simplicidad y bajo coste. Con instrumentación sencilla y protocolos de preparación simples, es posible ensamblar estructuras complejas y estables con un control nanométrico sobre su composición y estructura. La metodología LbL es especialmente adecuada para la integración de biomoléculas (proteínas, lípidos, DNA) en multicapas funcionales, ya que el proceso de ensamblaje se lleva a cabo en condiciones suaves. Las propiedades biológicas de estos materiales se mantienen o incluso mejoran tras su incorporación en los films. Otra ventaja de esta técnica es que permite recubrir sustratos de virtualmente cualquier tamaño y forma con films funcionales de manera sencilla y controlada. De particular importancia ha sido la extensión del método a la modificación de partículas coloidales. Aparte de su interés desde un punto de vista fundamental y aplicado, los coloides constituyen herramientas de gran potencial para la creación de estructuras de diseño específico en los campos de la bio y nanotecnología. La funcionalización vía LbL de partículas coloidales permite integrar múltiples funcionalidades en las partículas, y proporciona además una ruta para la creación de estructuras tridimensionales que facilitan la transición desde la nano- a la micro- y macroescala. La técnica LbL ha supuesto también un gran avance en el desarrollo de sistemas electroquímicos. Diversos materiales electroactivos pueden ser incorporados en las multicapas, junto con otras especies que proporcionan funcionalidades adicionales. Además, parámetros críticos como el grosor del film, el transporte de materia y la conductividad pueden ajustarse con precisión en estas estructuras, incrementando la capacidad de control sobre el funcionamiento final del sistema. En particular, las estructuras LbL han encontrado numerosas aplicaciones en el área de los biosensores electroquímicos. Estos dispositivos proporcionan una interfaz entre funciones biológicas específicas y procesos de transducción electrónicos, y ofrecen una alternativa con gran potencial para el desarrollo de plataformas de biodetección integradas. En el presente trabajo, la técnica LbL se emplea para ensamblar films multicapa de enzimas y polielectrolitos en la superficie de micropartículas de sílice. Dos enzimas diferentes, glucosa oxidasa (GOx) y peroxidasa (HRP) son co-inmovilizadas junto con capas precursoras e intermedias de polielectrolitos. En los films resultantes se desarrolla una reacción enzimática secuencial, con la conversión inicial de glucosa en acido glucónico y peróxido de hidrógeno, catalizada por GOx, y la posterior reducción del peróxido de hidrógeno a agua por acción de la HRP. El enfoque secuencial LbL permite explorar la influencia de diferentes combinaciones de polielectrolitos sobre la inmovilización y funcionalidad de los enzimas. Técnicas como la citometría de flujo, microscopía confocal y electrónica y medidas espectrofotométricas proporcionan información sobre la interacción entre los diferentes componentes de las capas, así como sobre la estabilidad de las suspensiones coloidales y el comportamiento de los films en presencia de los diferentes sustratos enzimáticos. Una funcionalidad electroquímica se integra adicionalmente en estos films mediante la incorporación de un polímero redox a la estructura. De este modo, los eventos específicos que tienen lugar durante la catálisis enzimática se transducen en una señal eléctrica. Las partículas nanoestructuradas asumen un doble papel en el sistema final. Por una parte, actúan como sustratos de alta área superficial para la fabricación de microreactores enzimáticos. Además, los coloides se incorporan en un film de polímero redox y se inmovilizan en la superficie de electrodos de oro, actuando como elementos de construcción para la fabricación de un biosensor electroquímico que permite la detección de glucosa y peróxido de hidrógeno. The layer-by-layer (LbL) coating of charged surfaces with oppositely charged materials is a powerful and versatile approach for the fabrication of functional molecular assemblies and interfaces. The key advantages of this technique over other methodologies such as self-assembled monolayers (SAM) or Langmuir-Blodgett (LB) are its unparalleled flexibility in combination with its simplicity and inexpensiveness. With simple instrumentation and easy preparation steps it is possible to assemble highly complex and stable architectures with nanoscale control over their composition and structure. The LbL approach is particularly suitable for the integration of biomolecules (proteins, lipids, DNA) into functional multilayers, since layer buildup is carried out under mild conditions. Many biologically relevant species can be incorporated into the films while maintaining or even improving their biological functions. A further advantage of this technique is that substrates of virtually any size and shape can be coated with functional films in a simple and controlled fashion. Of particular interest has been the extension of the LbL method to the modification of colloidal particles. Apart from their interest from a fundamental and applied point of view, colloids have emerged as powerful tools particularly suited to meet the challenge of creating tailored building blocks for the rapidly evolving fields of bio- and nanotechnology. The LbL functionalisation of colloidal particles provides a new route for the creation of composite architectures which allow the integration of nanoscale-defined materials into two- and three-dimensional structures. This ultimately opens the way not only to functional microsystems but also to the fabrication of macroscopic devices. One of the fields in which the LbL technique has represented a major advance is the development of electrochemical systems. Electrochemically active materials can be readily incorporated into multilayer films, together with other species which provide additional functionalities. Furthermore, critical parameters such as film thickness, mass transport and conductivity can be precisely tuned, allowing an increased control over the performance of the system. In particular, LbL assemblies have found many successful applications in the area of electrochemical biosensors. These devices provide an interface between biological functions and electronic signal-transduction processes, and offer great potential for the development of new miniaturised, low-cost, integrated biodetection platforms. In the present work, the LbL technique is employed to assemble multilayer films of enzymes and polyelectrolytes on the surface of silica microparticles. Two different enzymes, glucose oxidase (GOx) and horseradish peroxidase (HRP) are co-immobilised together with precursor and intermediate polyelectrolyte layers. In the resulting multilayer films a sequential reaction takes place, with the conversion of glucose to gluconic acid and hydrogen peroxide catalysed by GOx and the subsequent reduction of hydrogen peroxide to water catalysed by HRP. The sequential LbL approach allows to explore the influence of different polyelectrolyte combinations on the immobilisation and functionality of the enzymes. Flow cytometry, confocal and electron microscopy and spectrophotometric measurements provide information about the interaction between the different layer components, as well as the stability of the colloidal substrates and the behaviour of the multilayer films in the presence of the different enzyme substrates. An electrochemical functionality is further added to these films with the incorporation of an osmium-based redox polymer to the structure. In this way the specific chemical events taking place at the redox centers of the enzymes are transduced into an electrical signal. The nanostructured particles assume a multiple role in the final system. On one hand, they act as immobilisation substrates and high surface area carriers for the creation of enzymatic microreactors. Moreover, the LbL-coated colloids are embedded in a redox polymer film and immobilised on the surface of gold electrodes, acting as building blocks fo the fabrication of an electrochemical biosensor able to detect glucose and hydrogen peroxide.

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16

Bosch, Canals Begoña María. "A bioengineering approach for corneal endothelial regeneration." Doctoral thesis, Universitat Internacional de Catalunya, 2019. http://hdl.handle.net/10803/667398.

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Abstract (sommario):

Nowadays, there are approximately 10 million people worldwide with visual impairment due to corneal diseases. Currently, the main therapeutic solution is the transplant of a donor's cornea. The great majority of transplants is due to some failure in the inner layer of the cornea, which is called the corneal endothelium and this is mainly related with the inability of this layer to regenerate in vivo. However, transplants present several limitations such as the low number of healthy donors or immunological rejection by the patient. In order to overcome these problems, several researchers have focused in culturing corneal endothelial cells (CEC) to subsequently replace non-functional CEC. However, cell therapy is still very recent and still presents a series of drawbacks. For instance, using animal CEC or cells from other patients has shown to lead into immunological rejection. In order to avoid this, it is possible to use stem cells from the same patient, which have the ability to differentiate into many cell types, including the corneal endothelium. Currently, the stem cells used to regenerate CEC are mainly pluripotent stem cells, either embryonic stem cells (ESC) or induced pluripotent stem cells (iPSC), which are derived from adult cells. Despite their great potential for treating diseases, these types of stem cells present major limitations such as the risk of teratoma formation. In addition, they present other disadvantages such as ethical problems associated with the use of ESCs, safety problems related to iPSC since they requires the use of virus for their production hence limiting its clinical application. For this reason, and in order to solve the current problems in the regeneration of corneal endothelium, this thesis project uses dental pulp stem cells (DPSC) for the formation of CEC. DPSC are an accessible source derived from the same patient, avoiding possible future problems of rejection. In addition, the use of DPSC avoids the ethical and security problems associated with ESC and iPSC. Furthermore, DPSC and CEC have the same embryological origin, as they both arise from neural crest stem cells. In fact, DPSC express neural crest stem cells markers, which facilitates their differentiation into neural crest stem cells (NCSC), which is an intermediate step for the formation of CEC. Therefore, this thesis project uses a two-step protocol, where DPSC are differentiated into NCSC and, subsequently, NCSC are derived into CEC. Because the use of cell therapies alone may present limited cell viability once it is injected, the field of tissue engineering is a new discipline that has appeared to overcome this limitation. Tissue engineering combines the use of cells, biomaterials and biological molecules. It has been demonstrated that the use of different topographies in cell culture modulates cell behavior, and may have an effect on their functionality, cell distribution or cell size. Therefore, this thesis project applies tissue engineering as another strategy for the generation of functional CEC with its characteristic phenotype and morphology. For doing this, we have mimicked the natural CEC environment by cultivating the cells on substrates with different curvatures, composition or topographies that are able to mimic those of the human eye. In conclusion, this thesis project proposes the use of bioengineering, by differentiating CEC from stem cells derived from the patient and the use of biomaterials with different topographies and curvatures, for the regeneration of corneal endothelium.

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17

Gamito, Pedro Santos Pinto. "Soil bioengineering : prototyping a new conceptual framework." Thesis, University of Salford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248897.

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18

Al-Gosaibi, A. M. "Bioengineering properties of soil stabilisers and mulches." Thesis, University of Liverpool, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354534.

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19

Rebière, Alice. "Ultrashort laser bioengineering: Micropatterning of collagen fibers." Thesis, KTH, Tillämpad fysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-194398.

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20

Sclarsic, Sarah Mary Haiken. "A bioengineering roadmap for negative emissions technologies." Thesis, Massachusetts Institute of Technology, 2021. https://hdl.handle.net/1721.1/130839.

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Abstract (sommario):

Thesis: S.M., Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, February, 2021 Cataloged from the official PDF version of thesis. Includes bibliographical references (pages 49-59). Negative emissions technologies that can remove carbon dioxide from the atmosphere are a critical tool to limit global temperature rise and ocean acidification. Bioengineering capabilities have not been sufficiently assessed or utilized for the development of negative emissions technologies. Bioengineering holds the potential to improve the efficiency of some existing technologies and to create new methods of carbon removal. I review existing technologies to assess how bioengineering could improve them, focusing on technologies that could achieve at least 1 Gt of CO₂ removal per year. I also investigate and describe potential new methods of carbon removal that leverage bioengineering. Key questions for additional research are identified, as are key engineering targets for the development of improved negative emissions technologies. This evaluation of potential high-impact R&D work is intended to provide an initial roadmap for the development of bioengineered negative emissions technologies that are scalable, sustainable, and can remove gigatons of CO₂ from the atmosphere. by Sarah Mary Haiken Sclarsic. S.M. S.M. Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences

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21

Barbosa, Joana Cristina Pacheco. "Lichenicidin: regulation, expression and bioengineering in E.coli." Master's thesis, Universidade de Aveiro, 2012. http://hdl.handle.net/10773/9548.

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Mestrado em Biotecnologia Molecular A lichenicidina e um lantibiotico de classe II, naturalmente produzido por B. licheniformis I89. E constituida por dois peptidos denominados Blia e Blib. Este lantibiotico foi o primeiro a ser expresso completamente in vivo num hospedeiro Gram negativo (Escherichia coli). Neste trabalho, pretendeu-se avaliar o impacto da proteina LicR na biossintese da lichenicidina usando um sistema de expressao heterologa em E. coli. A estirpe de E. coli que nao contem o gene licR parece apresentar uma maior producao de lichenicidin do que a estirpe que contem todo o conjunto de genes envolvidos na sintese da lichenicidin. Assim, LicR parece nao apresentar qualquer funcao regulatoria em E. coli ou esta nao podera ser descrita segundo os mecanismos habituais de regulacao da producao de lantibioticos. Paralelamente um sistema de expressao foi construido para produzir cada um dos peptidos da lichenicidina separadamente, tendo sido comparados os niveis de producao de cada um dos peptidos. Este sistema foi usado com sucesso para produzir o peptido BliƒÀ mas nao apresentando qualquer vantagem sobre os sistemas ao nivel da producao. Finalmente, uma biblioteca de mutagenese do peptido Bliƒ¿ foi construida em E. coli e os clones obtidos foram analisados; a maioria dos clones obtidos apresentou bioatividade reduzida ou nula contra Micrococcus luteus. Alguns destes clones foram sequenciados para determinar qual(ais) a(s) mutacao(oes) presente(s) no gene licA1. Lichenicidin is a class II lantibiotic, naturally produced by Bacillus licheniformis I89 strain. It is composed by two peptides: Bliα and Bliβ. This was the first lantibiotic to be fully produced in vivo using a Gram negative host (Escherichia coli). Herein, the impact of LicR protein in lichenicidin biosynthesis was assessed, using an E. coli heterologous expression system. It was shown that the E. coli strain without the licR gene presented increased lichenicidin production, when compared with the strain containing the entire gene cluster. Thus, if LicR presents some regulatory function in E. coli, its role cannot be described according to the usually proposed regulation mechanisms involved in lantibiotic production. Also, an expression system was constructed to produce each lichenicidin peptide independently and this expression system was compared with other available systems in terms of production levels. The system was successfully used to obtain Bliβ peptide. However it did not show any advantage over the systems previously developed. Ultimately, a mutagenesis library of Bliα was constructed in E. coli and the clones were analyzed; the majority of the clones showed low or null bioactivity against Micrococcus luteus. Some of these clones were sequenced to determine which mutation(s) was present in the licA1 gene.

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22

Bisi, Maria Cristina <1983&gt. "Bioengineering of exercise: biomechanical and metabolic aspects." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2010. http://amsdottorato.unibo.it/2543/1/Bisi_MariaCristina_tesi.pdf.

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Abstract (sommario):

The field of research of this dissertation concerns the bioengineering of exercise, in particular the relationship between biomechanical and metabolic knowledge. This relationship can allow to evaluate exercise in many different circumstances: optimizing athlete performance, understanding and helping compensation in prosthetic patients and prescribing exercise with high caloric consumption and minimal joint loading to obese subjects. Furthermore, it can have technical application in fitness and rehabilitation machine design, predicting energy consumption and joint loads for the subjects who will use the machine. The aim of this dissertation was to further understand how mechanical work and metabolic energy cost are related during movement using interpretative models. Musculoskeletal models, when including muscle energy expenditure description, can be useful to address this issue, allowing to evaluate human movement in terms of both mechanical and metabolic energy expenditure. A whole body muscle-skeletal model that could describe both biomechanical and metabolic aspects during movement was identified in literature and then was applied and validated using an EMG-driven approach. The advantage of using EMG driven approach was to avoid the use of arbitrary defined optimization functions to solve the indeterminate problem of muscle activations. A sensitivity analysis was conducted in order to know how much changes in model parameters could affect model outputs: the results showed that changing parameters in between physiological ranges did not influence model outputs largely. In order to evaluate its predicting capacity, the musculoskeletal model was applied to experimental data: first the model was applied in a simple exercise (unilateral leg press exercise) and then in a more complete exercise (elliptical exercise). In these studies, energy consumption predicted by the model resulted to be close to energy consumption estimated by indirect calorimetry for different intensity levels at low frequencies of movement. The use of muscle skeletal models for predicting energy consumption resulted to be promising and the use of EMG driven approach permitted to avoid the introduction of optimization functions. Even though many aspects of this approach have still to be investigated and these results are preliminary, the conclusions of this dissertation suggest that musculoskeletal modelling can be a useful tool for addressing issues about efficiency of movement in healthy and pathologic subjects. L’ambito di ricerca di questa tesi riguarda la bioingegneria dell’esercizio fisico, in particolare l’integrazione tra conoscenze biomeccaniche e metaboliche. La relazione tra questi due aspetti consentirebbe una valutazione completa dell’esercizio fisico che potrebbe aiutare la pratica clinica in diversi ambiti (ottimizzazione della performance di atleti, comprensione e compensazione del consumo energetico nei pazienti protesizzati, identificazione di esercizi ad alto consumo calorico e basso carico alle articolazioni per pazienti in sovrappeso). Inoltre, potrebbe avere applicazioni tecniche nel design di macchine per il fitness e per la riabilitazione. Lo scopo di questo lavoro era di approfondire la conoscenza riguardante la relazione tra lavoro meccanico e costo energetico metabolico durante il movimento, attraverso l’utilizzo di modelli interpretativi. Il problema è stato affrontato attraverso l’utilizzo di modelli muscolo scheletrici che includono oltre alla descrizione meccanica anche la descrizione della spesa energetica muscolare e che quindi permettono di valutare il movimento umano sia in termini meccanici che in termini di spesa energetica. E’ stato identificato in letteratura un modello muscolo scheletrico dell’intero corpo che potesse descrivere sia aspetti meccanici che metabolici; tale modello è stato applicato e validato utilizzando un approccio guidato da dati sperimentali di cinematica e elettromiografia (EMG-driven). Il vantaggio principale nell’utilizzo di un approccio EMG-driven è evitare l’introduzione di funzioni di ottimizzazione arbitrarie che servono per risolvere il problema indeterminato delle forze muscolari attorno alle articolazioni. E’ stata quindi condotta un’analisi di sensitività sul modello con lo scopo di conoscere quanto le variazioni nei parametri possono influire sulle uscite del modello stesso: i risultati hanno mostrato che variazioni dei parametri all’interno di range fisiologici non influenzano largamente le uscite del modello. Successivamente, il modello muscolo scheletrico è stato applicato ai dati sperimentali al fine di valutare la sua capacità predittiva: la valutazione è stata prima effettuata su un esercizio semplice (leg press unilaterale) e poi su uno più completo (esercizio ellittico). Le predizioni energetiche del modello sono risultate vicine ai dati di consumo energetici stimati tramite calorimetria indiretta nei casi studiati, in particolare alle basse velocità di esercizio e a diversi livelli di intensità. In conclusione, l’utilizzo di modelli muscolo scheletrici per predire il consumo energetico è risultato promettente e l’uso di un approccio EMG-driven ha permesso di evitare l’utilizzo di funzioni di ottimizzazione. Sebbene i risultati ottenuti siano preliminari e molti aspetti dell’approccio proposto debbano essere ulteriormente studiati, le conclusioni di questa tesi suggeriscono che la modellazione muscolo scheletrica può essere uno strumento utile per rispondere a domande riguardanti l’efficienza del movimento in soggetti sani o patologici.

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23

Bisi, Maria Cristina <1983&gt. "Bioengineering of exercise: biomechanical and metabolic aspects." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2010. http://amsdottorato.unibo.it/2543/.

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Abstract (sommario):

The field of research of this dissertation concerns the bioengineering of exercise, in particular the relationship between biomechanical and metabolic knowledge. This relationship can allow to evaluate exercise in many different circumstances: optimizing athlete performance, understanding and helping compensation in prosthetic patients and prescribing exercise with high caloric consumption and minimal joint loading to obese subjects. Furthermore, it can have technical application in fitness and rehabilitation machine design, predicting energy consumption and joint loads for the subjects who will use the machine. The aim of this dissertation was to further understand how mechanical work and metabolic energy cost are related during movement using interpretative models. Musculoskeletal models, when including muscle energy expenditure description, can be useful to address this issue, allowing to evaluate human movement in terms of both mechanical and metabolic energy expenditure. A whole body muscle-skeletal model that could describe both biomechanical and metabolic aspects during movement was identified in literature and then was applied and validated using an EMG-driven approach. The advantage of using EMG driven approach was to avoid the use of arbitrary defined optimization functions to solve the indeterminate problem of muscle activations. A sensitivity analysis was conducted in order to know how much changes in model parameters could affect model outputs: the results showed that changing parameters in between physiological ranges did not influence model outputs largely. In order to evaluate its predicting capacity, the musculoskeletal model was applied to experimental data: first the model was applied in a simple exercise (unilateral leg press exercise) and then in a more complete exercise (elliptical exercise). In these studies, energy consumption predicted by the model resulted to be close to energy consumption estimated by indirect calorimetry for different intensity levels at low frequencies of movement. The use of muscle skeletal models for predicting energy consumption resulted to be promising and the use of EMG driven approach permitted to avoid the introduction of optimization functions. Even though many aspects of this approach have still to be investigated and these results are preliminary, the conclusions of this dissertation suggest that musculoskeletal modelling can be a useful tool for addressing issues about efficiency of movement in healthy and pathologic subjects. L’ambito di ricerca di questa tesi riguarda la bioingegneria dell’esercizio fisico, in particolare l’integrazione tra conoscenze biomeccaniche e metaboliche. La relazione tra questi due aspetti consentirebbe una valutazione completa dell’esercizio fisico che potrebbe aiutare la pratica clinica in diversi ambiti (ottimizzazione della performance di atleti, comprensione e compensazione del consumo energetico nei pazienti protesizzati, identificazione di esercizi ad alto consumo calorico e basso carico alle articolazioni per pazienti in sovrappeso). Inoltre, potrebbe avere applicazioni tecniche nel design di macchine per il fitness e per la riabilitazione. Lo scopo di questo lavoro era di approfondire la conoscenza riguardante la relazione tra lavoro meccanico e costo energetico metabolico durante il movimento, attraverso l’utilizzo di modelli interpretativi. Il problema è stato affrontato attraverso l’utilizzo di modelli muscolo scheletrici che includono oltre alla descrizione meccanica anche la descrizione della spesa energetica muscolare e che quindi permettono di valutare il movimento umano sia in termini meccanici che in termini di spesa energetica. E’ stato identificato in letteratura un modello muscolo scheletrico dell’intero corpo che potesse descrivere sia aspetti meccanici che metabolici; tale modello è stato applicato e validato utilizzando un approccio guidato da dati sperimentali di cinematica e elettromiografia (EMG-driven). Il vantaggio principale nell’utilizzo di un approccio EMG-driven è evitare l’introduzione di funzioni di ottimizzazione arbitrarie che servono per risolvere il problema indeterminato delle forze muscolari attorno alle articolazioni. E’ stata quindi condotta un’analisi di sensitività sul modello con lo scopo di conoscere quanto le variazioni nei parametri possono influire sulle uscite del modello stesso: i risultati hanno mostrato che variazioni dei parametri all’interno di range fisiologici non influenzano largamente le uscite del modello. Successivamente, il modello muscolo scheletrico è stato applicato ai dati sperimentali al fine di valutare la sua capacità predittiva: la valutazione è stata prima effettuata su un esercizio semplice (leg press unilaterale) e poi su uno più completo (esercizio ellittico). Le predizioni energetiche del modello sono risultate vicine ai dati di consumo energetici stimati tramite calorimetria indiretta nei casi studiati, in particolare alle basse velocità di esercizio e a diversi livelli di intensità. In conclusione, l’utilizzo di modelli muscolo scheletrici per predire il consumo energetico è risultato promettente e l’uso di un approccio EMG-driven ha permesso di evitare l’utilizzo di funzioni di ottimizzazione. Sebbene i risultati ottenuti siano preliminari e molti aspetti dell’approccio proposto debbano essere ulteriormente studiati, le conclusioni di questa tesi suggeriscono che la modellazione muscolo scheletrica può essere uno strumento utile per rispondere a domande riguardanti l’efficienza del movimento in soggetti sani o patologici.

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24

Schaefer, James William. "Bioengineering and reclamation to stabilize a lakeshore slope." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ40105.pdf.

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25

Tyber, Jeffrey Alan. "Mechanical behavior of materials for reconstructive bioengineering applications." Diss., Connect to online resource, 2005. http://wwwlib.umi.com/cr/colorado/fullcit?p1430186.

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26

Clark, J. E. "Principles of bioengineering with reference to East Nepal." Thesis, Cranfield University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526482.

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27

Lorenz, Astrid. "Bioengineering transgenic plants to detoxify nitroaromatic explosive compounds." Thesis, University of York, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.441030.

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28

Lassalle, Astrid. "Ultrashort Laser Bioengineering: Micropatterning of Cellularized Collagen Fibers." Thesis, KTH, Tillämpad fysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-208072.

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29

Waterhouse, Anna. "Bioengineering a coronary stent with covalently immobilised tropoelastin." Thesis, The University of Sydney, 2011. https://hdl.handle.net/2123/28916.

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This thesis describes the characterisation and development of covalently immobilised recombinant human tropoelastin (TE) on a plasma-activated coating (PAC) as a potential stent coating for the treatment of coronary artery disease. A biomimetic approach was used to create a biocompatible coating with an immobilised human protein to enhance biointegration of an implanted stent. A coating that enhanced endothelialisation while displaying low tbrombogenicity was developed and characterised in vitro and in vivo. Covalent binding of TE to PAC was verified using ELISA and radiolabelled TE. Modulating the gas composition of the PAC, and therefore its mechanical and biological properties, resulted in varying amounts of covalently bound TE. The nitrogen containing PA Cs covalently bound up to 89± 1 % of physisorbed TE. The N2/Ar PAC covalently bound a monolayer of TE and was chosen for further characterisation. The covalent binding capacity of PAC extended for at least a year, retaining 65±1 % of its covalent TE binding capacity. Restoration of the full covalent binding capacity was achieved upon heat treatment of the PAC. TE was shown to support the attachment and proliferation of endothelial cells (ECs) when physisorbed to tissue culture plastic (TCP). This was comparable to other adhesive extracellular matrix proteins, fibronectin and collagen. The morphology and distribution of ECs cultured on 316L SS, PAC and PAC+TE was investigated using reflective, fluorescence and scanning electron microscopy. PAC+TE supported increased endothelial attachment and proliferation compared to uncoated 3 l 6L SS and PAC. An EC phenotype was confirmed on 316L SS, PAC and PAC+TE by immunofluorescent labelling of endothelial cell specific markers, CD3 I and vWF. As the thrombogenicity of blood contacting medical devices is crucial, methodology was developed to test the haemocompatibility of metallic surfaces in vitro. In static adhesion assays using whole heparinised blood, PAC was found to confer low thrombogenicity compared to 3 l 6L SS, and nitrogen again modulated this property. PAC and PAC+TE showed lower thrombogenicity than 316L SS after 60 min incubation. A modified Chandler loop was developed to test the tbrombogenicity of metallic surfaces in the presence of flowing blood. PAC and PAC+TE were again found to display low thrombogenicity, resulting in a 3-fold increase in the time to thrombus formation compared to 3 I 6L SS. This effect correlated with a 65±1 % increase in soluble P-selectin, a platelet activation marker on 3 l 6L SS. No significant platelet activation occurred on PAC or PAC+TE. The low thrombogenicity of PAC was retained for between 3 and 7 months. Furthermore, TE coated 3 I 6L SS displayed lower thrombogenicity than uncoated 316L SS, or fibronectin-or collagen-coated 316L SS. The PAC was translated to a 316L SS laser cut stent for evaluation and in vivo testing. The PAC deposition was altered to coat all surfaces and resisted delamination. In vitro crimping and expansion of the PAC stent showed only the formation of nanocracks, compared to the large scale delamination observed on a commercially available Taxus Liberte stent. The covalent TE binding capacity and non-thrombogenicity of the PAC were maintained on the stent PAC. The endothelialisation of PAC and PAC+TE stents was evaluated in vivo. This study marks the first comparator analysis of bare metal stents (BMS), PAC and PAC+ TE stents in a well-characterised model of rabbit bilateral iliac stenting. PAC and PAC+ TE stents were well tolerated and showed no gross inflammatory response. Cell coverage of stent struts occurred by 7 days post-implantation with endotheJialisation occurring both between the struts and over the struts in all samples. PAC and PAC+ TE showed no difference in the rate of endothelialisation compared to BMS, the standard corrunerciaJly available stents. In further work, covalently immobilised TE was found to be susceptible to proteolytic cleavage by the common blood plasma proteases kallikrein and thrombin, which predominantly cleave TE at its arginine 515 residue. A mutant form of TE, R5 I 5A was shown to resist proteolytic cleavage at the 515 residue and thus retained the C-terminus of the protein which is required for cell attachment. This mutant form of TE retained the equivalent level of covalent binding to PAC and would therefore be a suitable candidate for application to a PAC stent for in vivo evaluation.

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30

CROCE, STEFANIA. "Mesenchymal stromal cells on bioscaffold for liver bioengineering." Doctoral thesis, Università degli studi di Pavia, 2020. http://hdl.handle.net/11571/1329186.

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Abstract (sommario):

Tissue bioengineering is the creation of functional tissues or whole organs by manufacturing body parts ex vivo, seeding cells on a supporting scaffold. The final goal of organ bioengineering is the use of the bioengineered organs as ‘replacement parts’ for the human body. The need for bioengineered livers is significant: currently, the only effective treatment for end-stage liver failure is orthotopic liver transplantation. However, the shortage of organ donors results every year in the death of many patients in the waiting list. Moreover, the advantage of this technology is the use of autologous cells that eliminates the need for post-transplant immunosuppression. In the present study, we decellularized pig livers and then repopulated them with allogeneic porcine mesenchymal stromal cells (pMSCs) to study the interaction between pMSCs and liver specific ECM. The final aim was to understand if ECM can influence and/or promote pMSCs toward differentiation into hepatocytes or hepatocyte-like cells without specific growth factor in culture medium. In our experimental project, porcine livers were obtained by a surgical technique similar to the one used for explant in a human cadaveric donor. Liver samples were cut and then decellularized through agitation with 0.15% SDS. The quality of the decellularization was evaluated both qualitatively and quantitatively, with histological staining and DNA quantification respectively. pMSCs were isolated from the porcine bone marrow (BM) and expanded in vitro. pMSC were characterized by assessment of morphology, proliferation capacity, immunophenotype and their differentiation ability. Then, pMSCs were used for seeding the scaffolds with static culture method. The repopulation of the recellularized scaffold was evaluated at 3, 7, 14 and 21 days after seeding with H&E stain, DAPI, MTT assay and SEM analysis, showing an increase in the cell number with increasing culture days. In order to determinate whether culture on liver ECM-scaffold could promote/address differentiation of pMSC towards hepatocyte, the transcriptional levels of some hepatic genes were tested. In particular, we evaluated six genes (ALB, AFP, HNF4a, Cyp1a1, Cyp7a1 and Krt18) associated to different phases of the hepatic development. A comparison with the expression profile was made with both porcine primary hepatocyte and pMSC. The observations obtained so far allow us to state that: i) our decellularization protocol is effective in the removal of the cells from native liver, respecting the parameters for decellularization without damage the structure of ECM; ii) pMSCs obtained from porcine BM have characteristic phenotypically and functionally comparable to those of their human counterparts and therefore they can be used as a model for experimental studies such as for liver ECM recellularization; iii) the static seeding strategy of pMSCs on the scaffold resulted to be effective in terms of ECM cell attachment, cell proliferation and migration inside the specimen, iv) the genic profile of cells seeded on ECM scaffold without any growth factors is more similar to pMSC suggesting that the only contact with liver specific ECM is not strong enough to induce a complete differentiation in HLCs. Despite this, we observed that Cyp7a1 gene, expressed in hepatocyte but not in MSC, was present in pMSC seeded scaffolds at each time points. In conclusion, we can observe that our results are in accordance with data reported in literature and sustain the possibility to use decellularizated organs as biological scaffold to create functional organs. We believe that our results may provide new insights toward a better understanding of early HLCs development on ECM-scaffolds. However, a more detailed decellularization process, a better cell differentiation capacity and a more detailed understanding of the interaction between cells and ECM could represent crucial steps in the progression of this research field.

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31

Groleau, Nicolas. "Model-based scientific discovery--a study in space bioengineering." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/12902.

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32

Jeewandara, Thamarasee M. "Bioengineering Stents for Proactive Biocompatibility: From Biomaterials to Stents." Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/14974.

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Abstract (sommario):

The thesis describes methods to characterize modified biomaterial surfaces in vitro, and investigate its short term implications at the artery interface in vivo. Plasma activated coating (PAC) technology has been previously deposited on a stainless steel biomaterial (316LSS), investigated in the stent form in vivo. Initial histopathology characterizations conducted with resin-artery-stents evaluate artery-stent interface interactions in vivo. The 7 day pilot study was followed by detailed material characterization and biofunctionalization on a modified cobalt chromium metal alloy L605, for the first time herein. The outcome of this study, is to transfer optimized plasma technology to new generation cobalt chromium stents (Multi Link 8, Abbott Vascular); currently in use to treat coronary artery disease (CAD). Plasma technology is unique for its ability to not delaminate from a biomaterial, while providing surface hemocompatibility, cytocompatibility, and controlled covalent attachment of protein tropoelastin (TE), in its native conformation. The present study addressed three key questions: 1. Do PAC 316LSS stents engineered with TE improve in vivo biocompatibility at 7 days? 2. How does PAC adhere to cobalt chromium alloy L605 (novel biomaterial) to prevent delamination under stress? 3. How does PAC-L605 maintain superior hemocompatibility and promote homogenous cell culture compared to alloy L605.

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33

Mummery, Gavin Thomas. "Developing a high-resolution bioengineering model for slope stability analysis." Thesis, University of Bristol, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435426.

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34

Sharma, Vaibhav. "Bioengineering of a novel fibrinalginate scaffold for tissue engineering applications." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/10037661/.

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Abstract (sommario):

Over the last few decades, developing reconstructed dermis with the potential of replacing the injured dermis is highly explored. Even though a range of dermal scaffolds are available commercially (Integra® and Matriderm®), none have shown the potential to regenerate injured skin similar to normal skin. Commercially available dermal scaffolds have a range of limitations such as wound contraction, scar formation and poor integration with the host tissue. Designing three dimensional scaffolds using tissue engineering approaches involves optimising the architectural design of the scaffold to promote cell adhesion, proliferation and differentiation to repair the injured tissue. The aim of this thesis was to design a foam-based dermal replacement fibrin-alginate scaffold using surfactants as a tool to introduce gradient porosity within the scaffold (pore range 20 - 270 μm). Initially, a range of non-ionic sugar surfactants were tested on the basis of foaming capacity, stability and their effect on the structure of the fibrin-alginate scaffold. Fibrinalginate scaffolds manufactured using a combination of three sugar based surfactants were highly porous with gradient pore structure, which was confirmed using microscopic techniques. The suitability of this scaffold for the repair of full thickness skin wounds was evaluated using microscopic characterization, viscoelastic measurements, in vitro biocompatibility using human dermal fibroblasts and in vivo testing using a porcine model. Further, this thesis has sought to examine and discuss the challenges faced during the translation phase of the fibrin-alginate technology from the R&D laboratory to a GMP facility for commercial purposes. Moreover, this study also investigated combining the fibrin-alginate technology with synthetic polymers like polydimethylsiloxane and poly(ε-caprolactone) for developing composites with applications for chronic wounds and non-union fractures respectively. A novel immunoassay was designed to comprehend the interfacial binding between the protein and the synthetic polymeric counterpart. This study has increased the current understanding of the use of surfactants on the structural behaviour of foam based protein scaffolds.

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35

Viray, Christina Marie. "Developing Innovative Bioengineering Platforms to Recapitulate Cell Microenvironments In Vitro." Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/24955.

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Abstract (sommario):

Bioprinting has recently emerged as a promising fabrication technique for developing 3D biologically functional, tissue-like constructs. Amongst the various bioprinting approaches, stereolithography (SLA) offers the highest feature resolutions that can be utilised to mimic the complex hierarchical architectures found within human tissues and organs. While significant efforts have been directed towards harnessing digital light processing (DLP) SLA techniques, less attention has been given towards the use of laser-based SLA and the corresponding development of cytocompatible bioresins for such setups. In this work, a novel hydrogel material system to be used as a bioresin was developed based on the biosynthetic polypeptide poly(L-glutamic acid) functionalised with tyramine moieties (PLGA-Tyr), and crosslinked using a visible light photoinitiator system. The gelation ability, swelling characteristics, degradation profiles, mechanical properties, and encapsulated cell viability were elucidated by varying the concentrations of PLGA-Tyr and the co-photoinitiator. This work also introduces a custom-built, cost-effective, single-photon laser SLA bioprinting system named the ‘MicroNC’. Methods to improve the diversity of scaffold geometries to be printed, feature resolution, and shape fidelity were systematically investigated using commonly used bioresins, achieving feature resolutions ranging between 8 to 20 µm. Most notably, it was shown that this bioprinting system could fabricate well-resolved hydrogel filaments (less than 8 µm in width) using the newly developed visible light hydrogel material system, which were capable of manipulating 2D single-cell morphology whilst supporting high cell viability (>90%) and proliferation up to 14 days. Overall, these experiments have underscored the exciting potential of using the visible light photoinitiated PLGA-Tyr material system for developing physiologically relevant in vitro hydrogel scaffolds for use in a wide range of biomedical applications such as tissue engineering, drug screening, disease modelling, and fundamental mechanobiological studies.

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36

Thiabgoh, Ongard. "Novel Magneto-LC resonance Sensors for Industrial and Bioengineering Applications." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7650.

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The scientific studies associated with material engineering and device miniaturization are the core concepts for future technology innovation. The exploring and tailoring of material properties of amorphous magnetic microwires, recently, have revealed remarkable high sensitive magnetic field sensitivity down to the picoTesla regime at room temperature. This superior magnetometer is highly promising for active sensing and real-time monitoring building block for modern industrial devices and healthcare applications. The low-field, high sensitivity regime of the GMI response over a wide frequency range (1 MHz - 1 GHz) in the Co-rich melt-extracted microwires was optimized through novel Joule annealing methods (single- and multi-step current annealing techniques). Optimization of current value through multi-step current annealing (MSA) from 20 mA to 100 mA for 10 minutes is the key to improving the GMI ratio, and its field sensitivity up to 760% and 925%/Oe at f ≈ 20 MHz. The respective GMI ratio and field sensitivity are 1.75 times and 17.92 times higher than those of the as-prepared counterpart. The employment of the MSA technique successfully enhances the surface domain structures of the Co-rich microwires. This alternative tailoring method is suitable for improving the GMI sensitivity for a small field detection. The high sensitive response of the GMI to a weak magnetic field is highly promising for biomedical sensing applications. Real-time monitoring of position, motion, and rotation of a non-stationary object is crucial for product packaging, conveying, tracking, and safety compliance in industrial applications. The effectiveness of current sensing technology is limited by sensing distance and messy environments. A new class of high-frequency GMI-based sensor was designed and fabricated using the optimal Co-rich microwire. The impedance spectrum from the optimal sensing element showed a high GMI ratio and high field sensitivity response at low magnetic fields. The GMI sensor based longitudinal effect was found to be more sensitive than the commercially available Gaussmeters. The practical utility of the high sensitivity of the miniaturized sensor at weak magnetic fields for far-off distance monitoring of position, speed and gear rotating was demonstrated. This GMI-based sensor is highly promising for real-time position detection, oscillatory motion monitoring, and predictive failure of a rotating gear for industrial applications. Monitoring the rate of respiration and its pattern is crucial to assessing an individual’s health or progression of an illness, creating a pressing need for fast, reliable and cost-effective monitors. A new sensor based on a magnetic coil, which is made of Co-rich melt-extracted microwire for the detection of small magnetic fields was fabricated. The 3 mm diameter coil is wound from a Co-rich magnetic microwire. Unlike some typical solenoids, the MMC is sensitive to small magnetic fields due to a significant change in impedance attributed to the high-frequency giant magneto-impedance (GMI) effect. An application of the MMC sensor for the detection of a position-varying source of a small magnetic field (~0.01 – 10 Oe) in real-time bio-mechanical movement monitoring in human was demonstrated. This newly developed MMC magneto-LC resonance technology is highly promising for active respiratory motion monitoring, eye movement detection and other biomedical field sensing applications.

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Giupponi, L. "BOTANICAL CONTRIBUTIONS TO IMPROVE THE ASSESSMENT OF SOIL BIOENGINEERING WORKS." Doctoral thesis, Università degli Studi di Milano, 2017. http://hdl.handle.net/2434/488066.

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The research described in this PhD dissertation was conducted during the period 2014-2016 at the Centre of Applied Studies for the Sustainable Management and Protection of Mountain Areas (Ge.S.Di.Mont. - University of Milan) in Edolo (BS) with the objective of devising botanical methods/tools that could be useful for improving the evaluation of soil bioengineering works in mountain areas. This research has led to the formulation of two floristic-vegetational indices: the Ecological Index of Maturity (EIM) and the Index of Ecological Success (IES). These indices were applied to three study areas located in mountainous areas of Lombardy (Northern Italy) affected by landslides which were followed by soil stabilization works using soil bioengineering techniques. On the basis of the results obtained, the indices have proven practical and functional for the evaluation of soil bioengineering works for slope stabilization as they consider their effectiveness in stabilizing soil as well as their efficiency in minimizing human impact on the ecosystem and landscape. This thesis also reports research to assess the effectiveness of the chromatographic fingerprinting of the extracts of fine roots for the identification of plant species. The results obtained showed that the analysis of chromatographic fingerprints is an effective method for the identification of some of the species studied whereas it is less useful for the identification of other species. This suggested ideas for further research on this topic and application both in soil bioengineering (e.g.: the evaluation of the success of the fine roots of plants used for soil stabilization) and in other sectors dealing with the study of the rhizosphere and plant (root)-soil interaction.

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Aebi, Dominic. "Bioengineering studies for improved fermentative hydrogen production and microbial electricity generation." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=107894.

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To supplement the non-renewable energy sources which are heavily relied-upon today, much research is being done to develop environmentally-friendly "Green Energy" and biologically-based "Bio Energy".The potential of microbial fuel cells (MFCs) as one of these next-generation energy sources was the first of two main aspects of this Master's research. Their suitability as a waste valorization by means of bioelectricity generation was investigated. The study employed a 50ml, single-chamber MFC system to compare substrate removal and electrical production using both minimal media and waste media derived from a glycerol process described by Jitrwung and Yargeau in 2010, both containing lactic acid as the main carbon substrate. The waste substrate out-performed the minimal media in terms of substrate removal, current production and electrical power. A maximum power density of 11.5mW/m2 was achieved. The main by-product of the system was propionic acid. The waste media required minimal processing prior to use in the MFC, which is quite favourable for upscaling possibilities.The second aspect of this project focused on bioenergy production by biohydrogen fermentation. It involved the development of a fully-defined media for use with anaerobic, hydrogen-producing Clostridium beijerinckii. Fully-defined media allow for improved metabolic analysis, and are previously unreported for this species. The novel medium, called "DDC Medium", showed excellent cell growth and hydrogen production compared to reinforced clostridial media, as well as 3 other defined clostridial media reported in literature. Hydrogen gas yield was 14ml/gCOD/L. Cost analysis showed an average cost reduction of 70% compared to the other media. It is expected for this media to be extremely useful in future metabolic engineering applications with C. beijerinckii.In exploring both fermentative and non-fermentative aspects of bioenergy, this project has revealed potential for improvement, as well as limitations, that stand between the current technology and viable, industrial-scale bioenergy production. En complément aux sources d'énergie non-renouvelable sur lesquelles nous comptons trop lourdement, beaucoup de recherche est effectuée afin de développer des sources d'énergie "vertes" ainsi que la bioénergie, deux types d'énergie plus respecteuses de l'environnement.Cette thèse a évalué dans un premier temps le potentiel de la technologie de la pile à combustible microbienne (PACM) comme source de bioénergie et méthode concurrante de traitement et valorisation de résidus aqueux. Un système PACM ayant une chambre unique de 50 mL a été utilisé afin de comparer l'enlèvement des substrats et la production de courant électrique obtenus lors de l'utilisation d'un media de culture à ceux obtenus en traitant un résidu de fermentation du glycerol, décrit par Jitrwung et Yargeau en 2010 comme contenant l'acide lactique comme source principale de carbon. Le résidu a surpassé le media de culture et ce, pour l'enlèvement de substrat, la production de courant et la puissance électrique. Une densité maximale de puissance de 11.5mW/m2a été atteinte. Le principal sous-produit de réaction a été identifié comme étant l'acide propionique. Les résultats démontrent la possibilité d'utiliser ce résidu dans une PACM et la non-nécessité de prétraiter le résidu diminue les risques et coûts associés à une mise à l'échelle d'un tel procédé. Dans un deuxième temps, les travaux de thèse ont permis de devélopper un média de culture complètement défini permettant l'étude d'une bactérie productrice d'hydrogène en conditions anaerobiques, Clostridium beijerinckii. Aucun media complètement defini n'avait été rapporté pour cette bactérie pourtant d'importance pour la production d'hydrogène par voie microbiologique. Un tel média est toutefois nécessaire pour effectuer les analyses metaboliques requises lors de l'étude de cette bactérie. Nommé ici "DDC Media", la composition developpée a démontré une croissance accrue des cellules et une production d'hydrogène augmentée en comparaison avec le média renforcé communément utilisé, ainsi qu'avec trois autres média définis pour d'autres espèces du même genre (Clostridium spp). Une production d'hydrogène de 14 ml/gCOD/L a été obtenue. L'analyse du coût du DDC medium a indiqué une réduction de 72% par rapport au coût du média renforcé et 68% par rapport au coût des médias définis pour d'autres espèces du même genre. La disponibilité de ce nouveau média défini sera très utile pour les études métaboliques de C. beijerinckii.En explorant divers aspects de la production de bioénergie, ce projet a fourni un outil et révelé certaines pistes de recherche qui permettront à plus long terme de lever les barrières limitant la production de bioénergie à grande échelle.

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Phairatana, Tonghathai. "Bioengineering of novel carbon-based biosensors for real-time biomedical use." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/58345.

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The aim of this thesis was to develop novel carbon-based biosensors and sensors for real-time metabolite and drug detection, to provide the next generation of medical devices which can give clinicians relevant chemical information in real-time at the patient bedside. An autocalibration system was developed using LabSmith programmable components to give precise fluid delivery and excellent temporal control of multiple liquid streams. This enables a 5-point calibration to be carried out using two solutions in 12 minutes. Systems using chitosan, poly(ethylene glycol)diglycidyl ether hydrogel, electrodeposition and selfassembly to immobilise enzymes on a combined needle electrode surface were studied and their performances were investigated using a microfluidic platform. The autocalibration system was combined with the graphene oxide-based biosensors in a microchip coupled with a microdialysis probe and was examined as a proof-of-concept clinical on-line analysis system. A reduced graphene oxide-based sensor was fabricated using a combined needle electrode for on-line neurotransmitter detection of dopamine. Its performance was compared with that of a platinum electrode. A microfluidic sensor based on a carbon nanotube-epoxy composite was fabricated to detect the presence of carboplatin (anti-cancer drug) in healthy tissue in real time during chemotherapy. Detection of carboplatin was carried out using differential pulse voltammetry firstly in a beaker, in which carbon nanotube-epoxy composite electrodes performed better than glassy carbon electrodes for oxidation of free purine bases and than DNA-modified carbon nanotube-epoxy composite sensors for detection of carboplatin. Carboplatin detection was then performed in a microfluidic platform. The methodology for on-line carboplatin detection was optimised in terms of the analysis time and for the repeated determination of carboplatin using the same electrode. Microdialysis and microfluidic techniques have been combined to give a proof-of-concept system real-time carboplatin detection using the carbon nanotube-epoxy composite sensors.

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Jorge, João Manuel Pereira. "Bioengineering of Lactococcus lactis through modulation of its major glucose transporter." Master's thesis, Faculdade de Ciências e Tecnologia, 2012. http://hdl.handle.net/10362/9061.

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Mak, Wing Cheung. "The applications of layer-by-layer technology in bioengineering and bioanalytics /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?BIEN%202004%20MAK.

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42

Merino, Araneda German Enrique. "Bioengineering requirements for the intensive culture of California halibut (Paralichthys californicus) /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.

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43

Barnes, Devon. "In vitro bioengineering applications of melt electrowritten and hydrogel composite scaffolds." Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/212352/1/Devon_Barnes_Thesis.pdf.

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Two-dimensional cell cultures provide an inaccurate representation of how cells develop and are affected by disease and injury. Scaffold-based tissue engineering techniques that combine novel biomaterials and printing methods could assist in the design of more physiologically relevant, three-dimensional experimental tissue models. This thesis investigated the application of carbohydrate glass as a sacrificial material toward producing perfusable hydrogel devices using melt electrowriting, the development and optimisation of a three-dimensional bioengineered bone marrow microenvironment, and a literature review of the approaches toward the development, imaging and analysis of resulting three-dimensional models.

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TRAVERSARI, GABRIELE. "Analysis of multi-phase systems relevant to bioengineering and materials science." Doctoral thesis, Università degli Studi di Cagliari, 2021. http://hdl.handle.net/11584/312667.

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In the thesis the focus is on the analysis of two multiphase systems related to biomedical engineering and materials science. The first part of the thesis is related to the long-term preservation of human Mesenchymal Stem Cells (hMSCs) from Umbilical Cord Blood (UCB) by means of cryopreservation, i.e. freezing the bio-specimens to cryogenic temperature, and drypreservation, i.e. air-drying at room temperature and atmospheric pressure. First, the peculiar osmotic behavior of hMSCs from UCB is analyzed by developing a novel mathematical model. Then, the addition and removal phases of a permeant Cryo-Protectant Agent (CPA) like dymethil-sulfoxide (DMSO) during a cryopreservation protocol is studied taking into account both the cytotoxic effect and osmotic injury (i.e. expansion lysis). Finally, a mathematical model is proposed to guide and support the development of a long-term preservation of hMSCs through air-drying. The second part of the thesis is related to the modeling of mechanical processing of powders by Ball Milling (BM). First the propagation of mechanically activated self-sustaining reactions during BM is investigated by numerical simulations. Then, a statistical description of the kinetics of processes activated by BM coupled with the mathematical description of advection cycles induced by plastic deformation is developed to model the refinement of the lamellar structure in composite Ag-Cu particles during the early stages of mechanical processing. Finally, considering the intrinsic statistical nature of this mechanical process, a kinetic model that combines a phenomenological description of the rheological behavior of molecular solids with the chemistry of interface reactions is developed.

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Nguyen, Vina Le. "Structure-Property Relations of the Exoskeleton of the Ironclad Beetle (Zopherus Nodulosus Haldemani)." Thesis, Mississippi State University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10642091.

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In this study, structure-property relationships in the ironclad beetle (Zopherus nodulosus haldemani) exoskeleton are quantified to develop novel bio-inspired impact resistance technologies. The hierarchical structure of this exoskeleton was observed at various length scales for both the ironclad beetle pronotum and elytron. The exocuticle and endocuticle layers provide the bulk of the structural integrity and consist of chitin-fiber planes arranged in a Bouligand structure. The pronotum consists of a layered structure, while elytron consists of an extra layer with “tunnel-like” voids running along the anteroposterior axis along with smaller interconnecting “tunnel-like” voids in the lateral plane. Energy dispersive X-ray diffraction revealed the existence of minerals such as calcium carbonate, iron oxide, zinc oxide, and manganese oxide. We assert that the strength of this exoskeleton could be attributed to its overall thickness, the epicuticle layer thickness, the existence of various minerals embedded in the exoskeleton, and its structural hierarchy. The thickness of the exoskeleton correlates to a higher number of chitin-fiber planes to increase fracture toughness, while the increased thickness of the epicuticle prevents hydration of the chitin-fiber planes. In previous studies, the existence of minerals in the exoskeleton has been shown to create a tougher material compared to non-mineralized exoskeletons.

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Wei, Chun-Shu. "Towards Brain Decoding for Real-World Drowsiness Detection." Thesis, University of California, San Diego, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10641645.

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A brain-computer interface (BCI) allows human to communicate with a computer by thoughts. Recent advances in brain decoding have shown the capability of BCIs in monitoring physiological and cognitive state of the brain, including drowsiness. Since drowsy driving has been an urgent issue in vehicle safety that causes numerous deaths and injuries, BCIs based on non-invasive electroencephalogram (EEG) are developed to monitor drivers’ drowsiness continuously and instantaneously. Nonetheless, on the pathway of transitioning laboratory-oriented BCI into real-world applications, there are major challenges that limit the usability and convenience for drowsiness detection (DD). To completely understand the association between human EEG and drowsiness, this study employed a large-scale dataset collected from simulated driving experiments with a lane-keeping task and EEG recordings. A DD-BCI that acquires EEG from only non-hair-bearing (NHB) areas was proposed to maximize the comfort and convenience. The performance of the NHB DD-BCI was validated and compared with that using whole-scalp EEG, showing no significant difference in the accuracy of alert/drowsy classification. In addition, a subject-transfer framework that leverages large-scale existing data from other subjects was proposed to reduce the calibration time of a DD-BCI. Alert baseline data were involved to enhance the efficiency of subject-to-subject model transfer. The subject-transfer approach significantly reduced the calibration time of the DD-BCI, exhibiting the potential in facilitating plug-and-play brain decoding for real-world BCI applications. Overall, this thesis presents the contributions to developing a DD-BCI for real-world use with maximal usability and convenience. The methodologies and findings could further catalyze the exploration of real-world BCIs in more applications.

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Middleton, Devon. "ACQUISITION, PROCESSING, AND ANALYSIS OF DIFFUSION TENSOR IMAGING AND ATROPHY MRI IN THE INJURED PEDIATRIC SPINAL CORD." Diss., Temple University Libraries, 2017. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/470546.

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Bioengineering Ph.D. Spinal cord injury has the potential to be debilitating, particularly in the pediatric population. Identification of the exact injury level can be difficult from conventional structural Magnetic Resonance Imaging (MRI) scans, and younger children often have difficulty in participating in the clinical examinations that define neurologic damage. Because of limitations of existing clinical examinations and conventional imaging, more advanced quantitative imaging techniques are important for improvement in diagnostic and prognostic evaluation of spinal cord injury. A quantitative characterization of the full spinal cord injury from both a functional and structural perspective has not been performed in pediatric subjects and has potential to provide important diagnostic and prognostic information. Diffusion tensor imaging (DTI) gives a non-invasive quantification of water diffusion in the spinal cord and can provide insight into white matter integrity, while high resolution volumetric imaging can determine cord cross sectional area reflecting atrophy occurring post injury. Multiple challenges exist in analysis of pediatric spinal cord data, including physiological motion, low signal-to-noise, thermal noise and image artifact, and cumbersome measurements of cord morphology. In this work, a complete pipeline for the acquisition and analysis of both functional DTI data and high resolution structural data is designed, tested, and implemented including MR image acquisition, motion correction, diffusion tensor estimation, region of interest analysis, and semi-automated cord cross sectional area measurement. Data for both healthy subjects and subjects with spinal cord injury is collected and significant correlations are shown between DTI and cord morphology metrics. This characterization of the injured spinal cord using both structural and functional data has the potential to offer important new information for examination of spinal cord injury. Temple University--Theses

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Pollard, David. "Histological Evaluation of the Effects of Diabetes on Renal Vasculature." Thesis, Clemson University, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=13422945.

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Diabetes mellitus currently affects 8.3% of the world’s population, roughly 387 million people as of 2014, with numbers rising steadily. Diabetes is a major risk factor for vascular pathology, affecting the vascular wall at the cellular and extracellular level. The field of tissue engineering has proven to have great potential in treating cardiovascular disease and kidney failure. In order to develop tissue-engineered replacements resistant to the alterations induced by a diabetic environment, the modifications of the native tissues are important to be elucidated. Cardiovascular remodeling is due to elevated levels of fatty deposits along the vessel wall, hyperglycemia and chronic inflammation. The major vascular matrix components, such as collagen and elastin, interact irreversibly with the elevated levels of blood glucose and lipids via oxidation and crosslinking processes resulting in the formation of advanced glycation end products and vascular stiffening. Adventitial fibroblasts, the “first-responder” to vascular injury, are involved in normal maintenance of blood vessels, contributing to repair and remodeling. Adventitial fibroblasts play an active role in the arterial response to injury, cytokines and stretch, which stimulate their activation and differentiation into myofibroblasts. Diabetes is also the most common cause of chronic renal disorders and end stage renal disease. Diabetes results in a wide range of alterations in renal tissue such as glomerular sclerotic lesions, hypertrophy of glomeruli, tubulointerstitial fibrosis, increased expression of myofibroblasts and inflammation that contribute to kidney dysfunction and diabetic nephropathy. The aim of this study was to show the histological changes of renal tissue associated with diabetes with an emphasis on remodeling of the renal vasculature. Kidney samples were explanted at a time point 3 months from diabetic and non-diabetic rats and were histologically analyzed for indications of pathological remodeling. The sample cross sections were stained and analyzed for early signs of diabetic nephropathy including glomerulus deterioration, vessel wall remodeling, and vascular cell dyfunction. This was done using hematoxylin & eosin, Masson’s trichrome, periodic acid schiff and various immunostainings for α-SMA, CD146, CD68, von Willebrand factor and collagen type IV. Dense perivascular collagen deposition could be seen under diabetic conditions. Increased macrophage infiltration was observed in diabetics as well as increased pericyte and endothelial cell expression suggesting upregulation of angiogenesis and increased remodeling and repair within the kidney. Myofibroblast activity, the main contributing cell to organ fibrosis, was upregulated in diabetics showing early signs of kidney fibrosis—a common outcome in diabetic nephropathy. In conclusion, determining the modifications induced by diabetes at a vascular cell and extracellular level could lead to finding optimal treatments for renal artery disease and improved kidney tissue engineering approaches.

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Khormaee, Sariah. "Optimizing siRNA Efficacy through Alteration in the Target Cell-Adhesion Substrate Interaction." Thesis, Harvard University, 2014. http://etds.lib.harvard.edu/hms/admin/view/59.

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Short interfering RNA (siRNA) is a class of nucleotide drugs with a profound potential to improve patient health through its ability to silence the expression of specific genes at the post-transcriptional level. However, the clinical application of siRNA therapeutics remains hindered by a lack of efficient delivery systems that deposit siRNA into the cytoplasm of cells, a step necessary for siRNA’s silencing effect. Much research has focused on the development of siRNA delivery agents to overcome this challenge. There are no standard pre-clinical models for testing of siRNA delivery agents, and investigators have chosen to evaluate efficacy in a variety of systems including in vitro tissue culture and animal models. These systems have vastly different cellular microenvironments which may modulate cellular behavior and affect the response of cells to siRNA, thus altering the apparent efficacy of siRNA delivery agents. The substrate on which cells adhere is one aspect of the microenvironment that has been previously shown to alter cellular behavior. In this work, we tested the hypothesis that changing the properties of cellular adhesion substrates can change the apparent efficacy of a siRNA delivery agent. Specifically, we used a commonly employed in vitro cationic lipid siRNA delivery vector and evaluated siRNA silencing efficacy in U251 cells seeded on alginate hydrogel surfaces. These surfaces were synthesized to have systematic variation in integrin ligand arginine-glycine-aspartate (RGD) density and elastic modulus. We found that an eightfold increase in RGD content of the alginate grown substrate increased siRNA knockdown efficacy from 25 ± 12% to 52 ± 10%, with constant concentrations of siRNA and delivery agent. We found no difference in siRNA mediated knockdown efficacy over the elastic modulus range tested (53-133 kPa). These results indicate that the cell-adhesion substrate interaction can modulate siRNA protein silencing efficacy, a finding important for evaluation of siRNA therapeutics in the in vitro setting.

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Fang, Shinong. "THE PREPARATION AND CHARACTERIZATION OF PRO-APOPTOTIC PEPTIDE ALA-VAL-PRO-ILE AND ITS DERIVATIVES." Master's thesis, Temple University Libraries, 2018. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/490963.

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Bioengineering M.S. The tetra-peptide sequence alanine-valine-proline-isoleucine (AVPI) is derived from a known inhibitor of apoptosis inhibitor proteins (IAPs) called Smac (second mitochondria-derived activator of caspases). Ala-Val-Pro-Ile can be further utilized as an anti-cancer agent by inhibiting the activities of apoptosis inhibitors so caspases can trigger apoptosis of cancer cells. AVPI, however, has poorly cell-penetration property thus limiting its ability to be utilized as a therapeutic agent for cancer treatments. We conjugated the AVPI molecule to a newly developed cell-penetrating peptide (CPP) called PepB to circumvent the situation of limited cellular availability. Solid Phase Peptide Synthesis (SPPS) methods have been utilized to prepared AVPI peptide derivatives. Key characterizations involve reverse-phase high-performance liquid chromatography (RP-HPLC), mass spectrometry, optical and fluorescence microscopy. Temple University--Theses

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