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Tesi sul tema "Engineering culture"
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1
Kunda, Gideon 1952. "Engineering culture : culture and control in a high-tech organization". Thesis, Massachusetts Institute of Technology, 1986. http://hdl.handle.net/1721.1/45688.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Sloan School of Management, 1987.MICROFICHE COPY AVAILABLE IN ARCHIVES AND DEWEY.
Bibliography: leaves 267-272.
by Gideon Kunda.
Ph.D.
2
Meneses, Alvarez Fernando. "Engineering a culture that promotes innovation". Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/117938.
Testo completoAbstract (sommario):
Thesis: S.M. in Management of Technology, Massachusetts Institute of Technology, Sloan School of Management, 2018.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 69-71).
In today's world, innovation has become a well-worn, sometimes over-used buzzword. Much of today's innovation is mainly linked with new technologies. Many companies talk about innovation using new metrics like "innovation premium," and they would like to be on the "Top 100 Most Innovative" list published by Forbes every year. This thesis seeks to answer the following questions: Do the CEOs of the most innovative companies create a unique environment within their organizations? Do they create an internal culture that supports employees who have ideas for innovative products or services? What can a CEO do to influence the company's shared attitudes, values, goals, and practices which in turn promote innovation? What are the main elements that influence internal culture and make it more innovative? To answer these questions, I reviewed the research literature by scholars and researchers on innovation. I also reviewed literature about the kind of organizational culture that promotes innovation. In addition, I interviewed nine leaders from several companies generally regarded as being innovative to inquire how they fostered an innovative environment. From this study, I identified three main elements that I think are key to creating a culture that promotes innovation. After determining the critical elements necessary for innovation, I interviewed 17 individuals from P-Automotive (a pseudonym). I asked them to discuss how their internal innovation culture relates to the three main elements. Based on what I learned from the research literature, the innovative leader interviews, and the case study of P-Automotive, I provide several general recommendations and several specific recommendations (for P-Automotive) for fostering an innovative organizational culture.
by Fernando Meneses Alvarez.
S.M. in Management of Technology
3
Ge, Cheng. "Novel technologies for cell culture and tissue engineering". Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:ab1014cf-80a4-4675-b607-96dc52c39b17.
Testo completoAbstract (sommario):
Cell culture has been a fundamental tool for the study of cell biology, tissue engineering, stem cell technology and biotechnology in general. It becomes more and more important to have a well-defined physiochemical microenvironment during cell culture. Conventional cell cultures employ expensive, manually controlled incubation equipment, making it difficult to maximize a cultures yield. Furthermore, previous studies use qualitative methods to assess cell culture proliferation that are inherently inaccurate and labour intensive, thereby increasing the cost of production. In addition, three dimensional cell culture, in scaffold, has been shown to provide more physiological relevant information as it mimic more accurate conditions that are similar to the physiological conditions of the human body compared with two dimension, which has special interest to regenerative medicine. Therefore, a portable and automated total-analysis-system (μTAS) was proposed with microenvironment control and quantitative analysis techniques to monitor cell proliferation and metabolic activity. The automated portable heating system was validated to be capable to maintain a stable physiochemical microenvironment, with little margin of error, for cellular substrate outside of conventional incubation. A standalone platform system was designed and fabricated with accurate temperature control by employing an optically transparent ITO-film with a large heating area. The transparency of the film is critical for continuous in-situ microscopic observation over long-term cell culture process. Previous studies have attempted to use ITO-film as a heating element, but were unable to distribute the heat evenly onto the microbioreactor platform. This nagging problem in the literature was improved through a novel film design. As a result, the ITO-film based heating system was evaluated and constructed successfully to serve as a heating element for long-term static cell culture with facilitated proliferation rate in gas-permeable PDMS microbioreactor outside of conventional incubation. In addition to maintaining a stable microenvironment, a non-invasive in-situ technology for monitoring cell viability and proliferation rate was constructed and developed based on bioimpedance spectroscopy (BIS). It was primarily focused on making decisions for structure and specification of proposed system-on a chip BIS measurement. The miniaturization of BIS system on microbioreactor platform was achieved by utilizing and integrating switching matrix array, impedance analyzer chip with reliable analogue-front-end circuitry. The realized system was verified with the DLD-1 cells and its monitored data were validated with conventional bioassays. Three dimensional cell cultures with scaffold is a key to the success of tissue engineering. Engineered cornea collagen scaffold may be feasible using re-seeding proper human cells onto a decellularized corneal scaffold. The quality of the scaffold and the interaction of the cells are critical to the key function (i.e transparency, haze and total transmittance) of final products. An integrated corneal collagen scaffold quality assessment system, via optical property inspection unit, was innovatively designed and realized with non-invasive and non-destructive characteristics. The H1299 cells were seeded onto inspected corneal scaffold and BIS system, which were realized in the previous chapter, were used to validate its applicability for 3D cell culture. The cell adhesion as an outcome at different scaffolds with different optical properties has revealed the importance of the microstructure of scaffold on the cell functions. The results showed the developed technologies can be used for the quality control of corneal scaffold and the fabricated μTAS not only enabled environmental control but, with BIS-based in-situ assay, it also facilitate the function (i.e adhesion) and viability monitoring with quantitative and qualitative analysis in 3D-alike cell culture. Additionally, by considering its low decontamination and cost-effective nature with compatibility for high-throughput screening applications, the fabricated and integrated systems has significant applications in tissue engineering.
4
Ferreira, Ana Raquel Santos. "A systems biology framework for pathway level culture media engineering: pplication to Pichia pastoris cultures". Doctoral thesis, Faculdade de Ciências e Tecnologia, 2012. http://hdl.handle.net/10362/9369.
Testo completoAbstract (sommario):
Dissertação para obtenção do Grau de Doutor em Engenharia Química e BioquímicaCulture media (CM) formulations contain hundreds of ingredients in aqueous solutions that may be involved in complex interactions in the same or competing pathways within the cell. This thesis proposes a new methodology for determining the optimal composition of CM that migrates from an empirical to a mechanistic or hybrid mechanistic CM development approach. A framework consisting in the execution of an array of cell cultures, endpoint exometabolomic assays and bioinformatics algorithm were brought together into a platform for CM engineering called Cell Functional Enviromics. This technology consists of a largescale reverse engineering approach that reconstructs cellular function on the basis of measured dynamic exometabolome data. To support this concept, a computational algorithm, called “envirome-guided Projection to Latent Pathways”, was developed. This method yields envirome-wide Functional Enviromics Maps (FEM), with rows representing medium factors, columns representing elementary (orthogonal) cellular functions and color intensity values, the strength of up-/down- regulation of cellular functions by medium factors. This method was applied to optimize Pichia Trace Metal salts for the yeast Pichia pastoris to improve the expression of heterologous proteins. An array of shake flasks experiments of the P. pastoris X33 strain were performed and used to build a FEM. Then, optimized CM formulations were calculated targeting predefined single-chain Fragment variable antibody (scFv) production improvements. Experimental validation shows a scFv productivity increase of approximately twofold, in relation to the control BSM recipe proposed by Invitrogen. These results were further validated in 2 L bioreactor experiments. Thereafter, scale-up to 50 L bioreactors was developed a mathematical model for further optimization of BSM salts in experiments of P. pastoris GS115. Direct adaptive (DO)-stat feeding controller that maximizes glycerol feeding through the regulation of DO concentration at 5% of saturation was developed and applied to the 50 L bioreactor, with the fully optimized CM composition.
Fundação para a Ciência e Tecnologia - bolsa de doutoramento SFRH/BD/36285/2007
5
Spears, Taylor Clancy. "Engineering value, engineering risk : what derivatives quants know and what their models do". Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/9839.
Testo completoAbstract (sommario):
This thesis examines the ‘evaluation culture’ of derivatives ‘quants’ working in the over-the-counter markets for interest rate derivatives tied to Libor. Drawing on data from interviews with quants, financial mathematicians, and economists conducted primarily in the United Kingdom and the United States, combined with fieldwork at derivatives ‘quant’ conferences and an extensive set of technical sources, this thesis explores the historical development and contemporary patterning of modelling practices that are used within derivatives dealer banks to price and hedge Libor-based interest rate derivatives. Moreover, this thesis uses the historical development of interest-rate modelling techniques, beginning in the late 1970s, as a lens through which to understand the establishment, differentiation and separation of this ‘derivatives quant’ evaluation culture as a body of knowledge and practice distinct from financial economics. The analysis is carried out in nine chapters. The thesis begins with an introductory chapter, a chapter reviewing the relevant sociological and historical literature on economic and financial modelling, and a chapter covering the research methodology employed in the thesis. In Chapters 4-5, I provide background on the mathematical techniques used by derivatives quants and financial economists, the social and institutional structure of the Libor derivatives markets, and the instruments that are traded in these markets. In Chapter 6, I explore the organisational patterning of modelling practices in these markets and highlight the tacit and experiential nature of quant expertise. In Chapters 7-8, I investigate the ‘social shaping’ of models that are currently used to price so-called ‘exotic’ Libor derivatives. These models originated within the discipline of economics and were designed for a set of purposes different from models currently used by derivatives quants. By tracing out how these models were adapted to serve as derivatives pricing ‘engines’ within banks, I highlight how modelling practices are shaped by the organisational contexts in which they are used.
6
Murzi, Escobar Homero Gregorio. "Understanding Dimensions of Disciplinary Engineering Culture in Undergraduate Students". Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/71775.
Testo completoAbstract (sommario):
The purpose of this study is to understand how engineering students perceive the patterns of culture at the disciplinary level using Hofstede's constructs (power distance, individualism, uncertainty avoidance, and masculinity). The methodology design for this study is mixed methods. More specifically, the design of this study is an explanatory sequential design that begins with the collection and analysis of quantitative data from a version of Hofstede's survey developed by Sharma (2010), followed by subsequent collection and analysis of qualitative data, with the qualitative analysis being informed by preliminary results from the initial quantitative phase. Results from the quantitative study led to a review of the literature regarding Hofstede's main critiques and how other authors have successfully implemented his model in different contexts, and qualitative data collection with semi-structured interviews with undergraduate students. There are three aims of this study, which are addressed and presented in three separate manuscripts. The first aim (Manuscript 1) was identifying if Hofstede's theory of dimensions of national culture can map to academic disciplines. Results from surveying 3388 undergraduate students provided scores on Hofstede's dimensions for each major. Responses matched the national culture of the students rather than the disciplinary culture; therefore, Hofstede's theory didn't map to explain cultural differences in academic majors. The second aim (Manuscript 2) of this study was to review the extensive available literature regarding the critiques of Hofstede's model and its implementation in different settings. Results provided with conceptual, and methodological critiques and misuse of his theory that allowed us to understand the value of his model to understand cultural differences at the national level, as well as the value of the dimensions to inform our qualitative research design. The third aim (Manuscript 3) of this study was to explore students' perceptions of disciplinary engineering culture and how it compared to other disciplines using a qualitative interview protocol that provided rich findings that complement the quantitative results. Results from interviewing 24 students in industrial and systems engineering, electrical and computer engineering, marketing, and industrial design provided with valuable information on how students perceive their disciplinary culture in terms of what it is valued, how they learn, how it is taught, why they learn, how it is going to be used in the workplace, and the reason for select the major. Implications for research and practice in the engineering education field are provided to inform how to make decisions on engineering curriculum, and engineering classrooms and try to find ways to improve some of the issues that engineering education has been facing for the last decades.Ph. D.
7
Ham, Stephanie Lemmo. "Engineering Tumor Models Using Aqueous Biphasic 3D Culture Microtechnology". University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron150470381711759.
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Boulais, Lilandra. "Cryogel-integrated hepatic cell culture microchips for liver tissue engineering". Thesis, Compiègne, 2020. http://www.theses.fr/2020COMP2561.
Testo completoAbstract (sommario):
L’un des enjeux de l’industrie pharmaceutique aujourd’hui est de développer des modèles de foie in vitro fidèles pour améliorer la prédictivité des études précliniques, notamment l’étude de la toxicité et de l’efficacité des médicaments candidats. Ces dernières années, l’ingénierie tissulaire, approche multidisciplinaire pour développer des tissus, a mené au développement de nouvelles méthodes de culture cellulaire. Parmi elles, les cultures de cellules en 3D ou en perfusion ont permis d’obtenir des activités hépatiques similaires à celles observées in vivo. L’objectif de cette thèse est de combiner ces deux méthodes de culture cellulaire pour créer un modèle de foie in vitro encore plus fidèle. Pour cela, nous cherchons à développer un cryogel d’alginate intégré en micropuce avec des propriétés mécaniques adaptables à celles du foie en fonction de l’état physiologique à reproduire (foie sain ou pathologique). Dans la première partie, nous développons et caractérisons le cryogel d’alginate au niveau microscopique et macroscopique, à l’extérieur (échantillons cylindriques) puis à l’intérieur de la biopuce. Trois paramètres sont étudiés ici : la température de cryopolymérisation, la concentration d’alginate ainsi que la quantité d’agents réticulants. Les propriétés mécaniques, la porosité, l’absorption, l’interconnectivité des pores et la résistance au flux sont analysés.La deuxième partie vise à cultiver des cellules hépatiques au sein de ce nouveau dispositif. Pour cette étude de faisabilité la lignée cellulaire HepG2/C3A est utilisée. Les résultats montrent des cellules viables et fonctionnelles (production d’albumine, transformation d’APAP). De plus, nous observons une structure tissulaire 3D, qui se maintient après retrait du cryogel d’alginate. La dernière partie a pour but de complexifier le modèle hépatique, notamment par des co-cultures. Pour se rapprocher de la structure du sinusoïde, des cellules hépatiques sont cultivées avec des cellules endothéliales (HUVEC) selon deux approches. De plus, la possibilité de suivre des cellules tumorales circulantes (MDA-MB-231) dans le système est étudiéeToday, one of the challenges for the pharmaceutical industry is to develop accurate in vitro liver models to improve the predictability of preclinical studies, in particular the study of the toxicity and efficacy of drug candidates. In recent years, tissue engineering, a multidisciplinary approach to develop tissues, has led to the development of new cell culture methods. Among them, cell cultures in 3D or in perfusion allowed to obtain hepatic activities similar to those observed in vivo. The objective of this thesis is to combine these two cell culture methods to create an even more accurate in vitro liver model. To do so, we are seeking to develop an alginate cryogel integrated into a microchip with mechanical properties adaptable to those of the liver depending on the physiological state to be reproduced (healthy or pathological liver).In the first part, we develop and characterize the alginate cryogel at the microscopic and macroscopic level, outside (cylindrical samples) and then inside the biochip. Three parameters are studied here: the cryopolymerization temperature, the alginate concentration and the quantity of cross-linking agents. Mechanical properties, porosity, absorption, pore interconnectivity and flow resistance are analyzed. The second part aims to culture liver cells within this new device. For this feasibility study the HepG2/C3A cell line is used. The results show viable and functional cells (albumin production, APAP transformation). In addition, we observe a 3D tissue structure, which is maintained after removal of the alginate cryogel. The last part aims to complexify the hepatic model, in particular by co-cultures. To get closer to the sinusoid structure, liver cells are cultured with endothelial cells (HUVEC) according to two approaches. In addition, the possibility to follow circulating tumor cells (MDA-MB-231) in the system is studied
9
Samuels, Fallon M. (Fallon Michele). "Valuable bridges : cable-stayed bridges and value engineering in American civil engineering culture, 1969-1979". Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/41760.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2007.Page 109 blank.
Includes bibliographical references (p. 99-108).
A history and theory of cable-stayed bridges in the context of a cultural discourse on civil construction projects' value, this thesis studies the significance of cable-stayed bridge designs to 'value engineering' objectives for major highway bridge projects of the 1970s. This study of preliminary designs and feasibility studies for highway bridges presents the alternate bridge designs versus alternative bridge typologies selected during this period as one instance of American civil engineering culture adapting to major bridge projects the economically measured but industrial approach to choosing, reconfiguring and eliminating construction systems of value engineering. Only as analytical mechanisms of bridge construction that figure as economically competitive in prevailing market conditions do the high-capital and technologically innovative bridge designs of the Luling Bridge (LA, 1978) and the Pasco-Kennewick Bridge (WA, 1977) develop into physical constructions built almost exclusively with federal highway funds. This shift in cable-stayed bridge designs' fate from abandoned projects in the 1960s is discussed as the reflection of structural engineers' engaging in the post-capitalist practices of analytical and then physical systems building, decision analysis, speculation as well as the interdisciplinary cultures from which these concepts stem. Critical studies of preliminary designs and construction industry data circa 1970 reveal cable-stayed bridge type selections to be at once the linchpin to politicization of VE in American highway bridge building by 1979 and the Achilles heel of an American civil engineering culture that sought a renaissance in bridge engineering not a redefinition of its principles through a new method of planning for alternate futures.
by Fallon M. Samuels.
S.M.
10
Chen, Guoping. "Design and Synthesis of Hybrid Biomaterials for Cell-Culture Engineering". Kyoto University, 1997. http://hdl.handle.net/2433/160822.
Testo completoAbstract (sommario):
本文データは平成22年度国立国会図書館の学位論文(博士)のデジタル化実施により作成された画像ファイルを基にpdf変換したものであるKyoto University (京都大学)
0048
新制・課程博士
博士(工学)
甲第6840号
工博第1591号
新制||工||1064(附属図書館)
UT51-97-H224
京都大学大学院工学研究科材料化学専攻
(主査)教授 升田 利史郎, 教授 砂本 順三, 教授 田中 渥夫
学位規則第4条第1項該当
11
Sims, Benjamin Hayden. "On shifting ground : earthquakes, retrofit and engineering culture in California /". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC IP addresses, 2000. http://wwwlib.umi.com/cr/ucsd/fullcit?p9975893.
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Senior, Richard. "Optimising culture conditions for tissue engineering large articular cartilage constructs". Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/7716/.
Testo completoAbstract (sommario):
Current surgical approaches to treating damage to articular cartilage, a highly specialised connective tissue, are limited in their ability to regenerate functional hyaline tissue. This has provided a driving force for the development of patient-specific, tissue engineered treatments. To date the majority of in vitro studies have focussed on engineering relatively small-dimension constructs; however justification remains for the production of large pieces of cartilage tissue. The aim of this research was therefore to investigate the potential for tissue engineering large, high quality cartilage constructs using several different culture methodologies Both small 'pin' (6 mm diameter) and large 'plate' (15 x 10 mm) constructs were successfully produced using primary bovine articular chondrocytes, a poly(glycolic acid) scaffold material and various culture conditions; static, semi-static and a rotating wall vessel (RWV) cell culture system. Small pin constructs cultured under standard static and semi-static conditions demonstrated a biochemical composition similar to that previously reported in published studies. Plate constructs cultured under static and semi-static conditions demonstrated an increased sulphated GAG and collagen type II content over their small pin counterparts, with an architecture possessing numerous lacunae and some zonal organisation. The Synthecon™ rotating wall vessel (RWV) bioreactor did not provide a suitable environment to engineer large plate constructs in standard cell culture medium. Due to their weight the constructs 'tumbled', resulting in damaged tissue with a poor quality extra cellular matrix rich in fibrous collagen type I. The design of a lightweight PTFE scaffold retention frame and the development of a dextran-modified, increased viscosity culture medium permitted the support of large constructs even at low vessel rotational RPM. The use of high viscosity culture medium in all culture environments however was found to have a detrimental impact on tissue quality, reduced mass transfer resulting in far lower matrix accumulation. It was concluded that large cartilage constructs may be produced under standard semi-static conditions that demonstrate hyaline-like features but biological quality was sacrificed. It was also concluded that an increased viscosity culture medium can demonstrate rheological properties comparable to those of synovial fluid, however in conjunction with the low-shear RWV bioreactor does not provide an ideal environment for engineering large cartilage constructs. The hydrodynamic properties of the increased viscosity culture medium could prove beneficial for the tissue engineering of articular cartilage constructs under a different bioreactor configuration.
13
O'Loughlin, Bryan. "Safety culture during major organisational change". Thesis, Aston University, 1998. http://publications.aston.ac.uk/13286/.
Testo completoAbstract (sommario):
This research examines the effect of major changes, in the external context, on the safety culture of a UK generating company. It was focused on an organisation which was originally part of the state owned Central Electricity Generating Board and which, by the end of the research period, was a self-contained generating company, operating in a competitive market and a wholly owned subsidiary of a US utility. The research represents an attempt to identify the nature and culture of the original organisation and to identify, analyse and explain the effects of the forces of change in moulding the final organisation. The research framework employed a qualitative methodology to investigate the effects of change, supported by a safety culture questionnaire, based on factors identified in the third report of the ACSNI Human Factors Study Group; Organising for Safety, as being indicators of safety culture. An additional research objective was to assess the usefulness of the ACSNI factors as indicators of safety culture. Findings were that the original organisation was an engineering dominated technocracy with a technocentric safety culture. Values and beliefs were very strongly held and resistant to change and much of the original safety culture survived unchanged into the new organisation. The effects of very long periods of uncertainty about the future were damaging to management/worker relationships but several factors were identified which effectively insulated the organisation from any of the effects of change. The forces of change had introduced a beneficial appreciation of the crucial relationship between safety risk assessment and commercial risk assessment. Although the technical strength of the original safety culture survived, so did the essential weakness of a low level of appreciation of the human behavioural aspects of safety. This led to a limited, functionalist world view of safety culture, which assumed that cultural change was simpler to achieve than was the case and an inability to make progress in certain areas which were essentially behavioural problems.
14
Theil, Ian. "Anchorage-dependent mammalian cell culture". Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=56768.
Testo completoAbstract (sommario):
Genetically engineered anchorage-dependent human embryonic kidney (293) cells were cultured at 37$ sp circ$C on 1 mm thick sheets of a fibrous polymeric matrix having an average fibre diameter of 10.2 $ mu$m and a void fraction of 0.81 using Dulbecco's Modified Eagle's Medium (DMEM) supplemented with 10% fetal bovine serum (FBS) and 2.5 mM glutamine. Immobilization efficiencies above 70% were observed when cells were added to 100 mL spinner flasks (operating at 60 rpm) containing 70 mL of medium and two 1 x 1 cm squares of matrix (total gross area of 2 cm$ sp2$) fastened to the base of the stirrer shaft. Loadings in excess of 2.4 $ times 10 sp7$ cells per cm$ sp2$ of matrix were measured after 2 h.The state of the cultures was followed by measuring the consumption of glucose and glutamine and the production of lactate and ammonium.
15
Rappel, Michael J. "Maintaining islet quality during culture". Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/38961.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2007.Includes bibliographical references (p. 262-274).
Islet transplantation has become a promising treatment for type I diabetes mellitus due to recent success since the development of the Edmonton Protocol. Islet culture prior to transplantation is standard practice in most clinical islet programs. Conventional culture conducted on polystyrene vessels can impose oxygen limitations even at relatively low tissue surface densities. High density islet culture is desirable because it reduces space and handling requirements during culture, but it exacerbates oxygen (02) limitations, causing a reduction in islet viability. The overall objective of this thesis was to maintain islet quality during static culture. As a chemical engineer, I focused on addressing transport limitations present in conventional culture techniques. After demonstrating culture in the absence of 02 transport limitations resulted in nearly 100% recovery of the original viable tissue placed into culture when the combined non-adherent and adherent tissue were considered, I examined the effect of tissue surface density on the recovery of islet tissue, its viability, and its purity for conventional normoxic culture on a polystyrene dish. With conventional culture, the fractional recovery of viable tissue decreased sharply as viable tissue density increased.
(cont.) To improve islet quality in high density culture, I investigated use of elevated ambient 02, reduced culture temperature, and culture on an oxygen-permeable silicone rubber membrane. By applying a theoretical 02 transport model, I investigated how 02 transport changes for each culture condition and compared predictions to the experimental data to determine whether 02 is limiting during high density culture using these new techniques. At high tissue surface densities, the fractional recovery of viable tissue was higher with culture on polystyrene in elevated (56%) 02 or culture at reduced temperature (24'C), and even higher with normoxic culture on a silicone rubber membrane. Theoretical predictions based on 02 transport were qualitatively similar to experimental results but in general overpredicted the amount of viable tissue recovered. Additional theoretical calculations indicated simplifications made when modeling oxygen along with glucose and pH changes during culture could account for the slight overprediction. In conclusion, in high density culture, recovery of viable tissue (1) decreases as culture density increases on a polystyrene surface; (2) increases with increasing external 02; and (3) increases substantially with culture on silicone rubber by removing 02 limitations.
(cont.) The techniques examined significantly improve tissue oxygenation compared to conventional culture, and allow tissue to be cultured at higher densities without a reduction in viability. These methods can be easily implemented, which would enable clinical centers to reduce space and handling requirements during culture prior to transplantation without the reduction in islet viability that can occur with conventional methods, and thereby maximize the use of limited islet resources.
by Michael James Rappel.
Ph.D.
16
Akmal, Mohammed. "The use of dynamic culture devices in articular cartilage tissue engineering". Thesis, University College London (University of London), 2006. http://discovery.ucl.ac.uk/1444064/.
Testo completoAbstract (sommario):
Tissue engineered repair of articular cartilage has now become a clinical reality with techniques for cell culture having advanced from laboratory experimentation to clinical application. Despite the advances in the use of this technology in clinical applications, the basic cell culture techniques for autologous chondrocytes are still based on primitive in-vitro monolayer culture methods. Articular chondrocytes are known to undergo fibroblastic change in monolayer culture as this is not their normal state in-vivo. They are more likely to maintain their phenotype when cultured in three dimensional environments. In this state they become spherical in shape and synthesise normal cartilage matrix products. Various substances are being presently investigated with the aim of designing a suitable material that is biocompatible, biodegradable and suitable for implantation. The major problem of culturing cells in three dimensional scaffolds is the limitation posed by the biomaterial on nutrient diffusion to cells deep within the scaffold. In order for this technology to succeed in clinical practice there is a important need to develop solutions to overcome these diffusional restraints. The use of dynamic culture devices which can, not only stimulate chondrocytes, but also maintain their original characteristics are investigated in this project. This thesis tests the hypothesis that culture within a dynamic culture device ie a rotating wall vessel bioreactor or roller bottles, enhances proliferation and cartilage-specific matrix synthesis by chondrocytes seeded in a three dimensional construct. The long term survival of chondrocytes in hydrogel matrices is also examined and cell cultures in dynamic devices are compared with traditional static culture systems. Biochemical, histological and immunostain data is presented an the possibility of using human cells is also explored.
17
Patel, Anita. "The development of a microscaffold culture system for tissue engineering bone". Thesis, University of Birmingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.410321.
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Alcorn, Aaron L. "Modeling Behavior: Boyhood, Engineering, and the Model Airplane in American Culture". Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1220640446.
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Alcorn, Aaron L. "Modeling behavior boyhood, engineering, and the model airplane in American culture /". online version, 2009. http://rave.ohiolink.edu/etdc/view.cgi?acc%5Fnum=case1220640446.
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Chattopadhyay, Devamita. "Studies on protective additives in cell culture /". The Ohio State University, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487861796818776.
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Johnson, Chad E. "Matrix metalloproteinases and the engineering of a vascular construct". Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/20155.
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Lee, Kevin Shao-Kwan. "Microscale controlled continuous cell culture". Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/64579.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 489-500).
Measurements of metabolic and cellular activity through substrate and product interactions are highly dependent on environmental conditions and cellular metabolic state. For such experiments to be feasible, continuous cultures are utilized to ensure consistent conditions. However, since medium must be replenished every cell doubling time, costs can be prohibitive in large reactors. An integrated microscale bioreactor with built-in fluid metering and environmental control will enable programmed experiments capable of generating reproducible data routinely. This work develops an instrument capable of supporting automated microscale continuous culture experiments. The instrument consists of a plastic-PDMS device capable of continuous flow reactions without volume drift. A novel bonding process is invented to fabricate devices with chemically stable interfaces against water, acids, and bases. We introduce a direct CNC machining and chemical bonding fabrication process for production of fluidic devices with a 1 mL working volume, high oxygen transfer rate (kLa ~ 0.025 s-1), fast mixing (2 s), accurate flow control (± 18 nL), and closed loop control over temperature, cell density, oxygen, and pH. Providing control over environmental parameters allows the system to perform different types of cell culture on a single device, such as batch, fed-batch, chemostat, and turbidostat continuous culture. Validation experiments demonstrate that cells can be grown to high optical densities (OD = 50) and production of commercially relevant chemicals such as DNA vaccines are comparable to large scale bench fermentations. Continuous cultures are also demonstrated without contamination for 3 weeks in a single device and both steady state and dynamically controlled conditions are possible, allowing observations of cell metabolic dynamics.
by Kevin Shao-Kwan Lee.
Ph.D.
23
Zupke, Craig Allen. "Metabolic flux analysis in mammalian cell culture". Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12661.
Testo completo
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Valls, Margarit Maria. "Development of an advanced 3D culture system for human cardiac tissue engineering". Doctoral thesis, Universitat de Barcelona, 2017. http://hdl.handle.net/10803/458734.
Testo completoAbstract (sommario):
Ischemic heart disease is a major cause of human death worldwide owing to the heart minimal ability to repair following injury. Other than heart transplantation, there are currently no effective or long-lasting therapies for end-stage heart failure. Therefore, it is crucial to develop not only alternative therapies that potentiate heart regeneration or repair, but also new tools to study human cardiac physiology and pathophysiology in vitro. In this context, cardiac tissue engineering arises a promising strategy, as it is aimed at generating cardiac tissue analogues that would act as in vitro models of human cardiac tissue or as surrogates for heart repair. Thus, having 3D human cardiac tissue constructs resembling human myocardium could revolutionize drug discovery and toxicity testing, cardiac disease modelling and regenerative medicine.
An strategy to obtain reliable cardiac tissue constructs is to mimic the native cardiac environment. The classical approach is based on seeding cardiomyocytes in biocompatible 3D scaffolds, and then culturing the construct in a biomimetic signaling system, usually a bioreactor. Although major advances have been made, the generation of thick and mature tissue constructs from human induced pluripotent stem cells-derived cardiomyocytes (hiPSC-CM) is still a challenge. Therefore, the hypothesis of our study is that the combination of hiPSC-CM with 3D scaffolds and appropriate regulatory signals may lead to the generation of mature human cardiac tissue constructs resembling human myocardium, both functionally and structurally. To address this, we have characterized a collagen-based 3D scaffold and established an efficient method for cell seeding into the scaffold. We have also developed a parallelized perfusion bioreactor system, which ensures an effective mass transport between cells and culture medium and allows culturing multiple replicas of tissue constructs. In addition, we have designed and fabricated a perfusion chamber including electrodes to electrically stimulate cells during culture, as well as to monitor tissue function. With this advanced 3D culture system, we have been able to generate thick 3D human cardiac constructs with tissue-like functionality. Our results indicate that perfusion of culture medium combined with electrical stimulation and collagen-based scaffold improve the structural and functional maturation of hiPSC-CM. In general terms, electrical stimulation has improved the structural organization, alignment and coupling of cardiomyocytes in our cardiac tissue constructs. Moreover, electrical stimulation has promoted the formation of synchronous contractile constructs at the macroscale with improved electrophysiological functions. Through the development of a new electrophysiological recording system, we report for the first time to our knowledge a technique that provides information about the electrical activity of intact cardiac tissue constructs in real time. Specifically, the combination of action potentials generated by hiPSC-CM composing cardiac constructs produces ECG-like signals, which could be monitored online. Finally, we have demonstrated the ability of stimulated human cardiac tissue constructs to detect drug-induced cardiotoxicity, as typical features of arrhythmias (e.g. prolongation of RR intervals and regular blockades) could be observed upon treatment with sotalol.
Taken together, results indicate that macroscopic human cardiac tissue constructs with tissue-like functionality can be obtained through the use of our advanced 3D culture system. We have studied the effects of electrical stimulation on cardiomyocytes at multiple levels: molecular (presence, distribution and expression of cardiac proteins), ultrastructural (sarcomere width and presence of specialized cellular junctions), cellular (morphology and alignment), and functional (amplitude, directionality and strain of contractions, and electrophysiological recordings). Findings validate our in vitro approach as a valuable system to obtain 3D cardiac patches with an improved maturity and functionality. Importantly, the online monitoring system developed in this study can provide essential electrophysiological information of intact cardiac tissue constructs, which opens up myriad possibilities in the field of cardiovascular research.La cardiopatia isquèmica és una de les principals causes de mort a nivell mundial. Exceptuant el trasplantament de cor, les teràpies actuals són insuficients per restablir la funció cardíaca. Per tant, cal desenvolupar teràpies alternatives que fomentin la regeneració i/o reparació del cor, així com també noves eines per estudiar la fisiologia i fisiopatologia cardíaca in vitro. Una de les estratègies més prometedores és l’enginyeria tissular cardíaca, ja que té com a finalitat generar constructes de teixit cardíac que mimetitzin el teixit real. Aquests constructes podrien utilitzar-se com a models in vitro del miocardi humà i també com a empelts per reparar el cor malmès. Per obtenir constructes de teixit cardíac humà cal reproduir l’entorn cardíac real. Una de les estratègies més habituals consisteix en sembrar cardiomiòcits en una estructura 3D (bastida), i després cultivar el constructe en un sistema de senyalització biomimètic, normalment un bioreactor. Tanmateix, generar constructes grans i semblants al miocardi humà adult a partir de cardiomiòcits humans derivats de cèl·lules mare de pluripotència induïda (hiPSC-CM) segueix sent un repte. Així doncs, la hipòtesi d’estudi és que combinant hiPSC-CM amb una bastida 3D i estímuls biofísics adequats, es podrien generar constructes de teixit cardíac semblants al miocardi humà tant a nivell estructural com funcional. Per abordar la hipòtesi, en aquest treball s’ha caracteritzat una bastida 3D constituïda principalment per col·lagen i s’ha definit un mètode eficient per sembrar cardiomiòcits dins l’estructura. A més a més, s’ha desenvolupat un bioreactor de perfusió de sistema en paral·lel que assegura un transport de massa efectiu entre les cèl·lules i el medi de cultiu. També s’ha dissenyat una càmera de perfusió que inclou elèctrodes per estimular elèctricament les cèl·lules durant el cultiu, així com també per monitorar la funció del teixit artificial. Amb aquest avançat sistema de cultiu, s’han generat constructes de teixit cardíac humà 3D amb una funcionalitat semblant a la del teixit real. A més a més, el sistema ha permès monitorar l’electrofisiologia del teixit artificial en temps real, així com també demostrar el paper crucial de l’estimulació elèctrica per obtenir constructes amb una funcionalitat òptima.
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Kutty, Jaishankar K. "Engineered micro-environments and vibrational culture systems for vocal fold tissue engineering". Connect to this title online, 2008. http://etd.lib.clemson.edu/documents/1219848273/.
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Odeleye, A. O. O. "Engineering characterisation of single-use bioreactor technology for mammalian cell culture applications". Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1464038/.
Testo completoAbstract (sommario):
The thesis describes an experimental investigation of the fluid dynamics within novel single-use bioreactors (SUBs), including stirred, rocked and pneumatically driven mixing systems. Biological studies to ascertain the impact of hydrodynamic conditions within these systems, on the growth and protein productivity of a mammalian cell line, are also presented. Two-dimensional velocity measurements within different SU technology were acquired with the use of a whole flow field laser-based technique, Particle Image Velocimetry (PIV). Fluid dynamic characteristics including velocity, turbulence, turbulent kinetic energy and vorticity were determined from time-resolved and phase-resolved velocity measurements. Commercial bioreactor systems were modified, if needed, in order to perform experiments within bioreactors commonly used for cell culture experiments, in preference to using vessel mimics. The fluid flow characteristics in both the impeller region and bulk fluid of a single-impeller stirred bioreactor were investigated, facilitating an enhanced understanding of the spatial distribution of velocity and turbulence throughout the vessel. PIV was also used to study the flow in a dual-impeller stirred bioreactor, providing a rare examination of the interaction between the flow fields generated by two impellers. The whole flow field velocity and turbulence characteristics measured within a rocked bag and pneumatically driven vessel, allow a unique insight into the flow pattern and turbulence distribution within two novel cell culture systems. Cell viability, size, growth, protein productivity and metabolites concentration were monitored under different cell culture operating conditions. Cell culture experiments, combined with the hydrodynamic information acquired using PIV, offer an insight into the physiological response of the cells to highly disparate flow conditions. This information helped to understand how the hydrodynamics induced by novel commercially used mixing systems, can impact upon a mammalian cell line. Having implications for an augmented capacity for cross-compatibility, in addition to enhanced strategies for scale translation and optimal bioreactor design.
27
Chu, Hyejin. "Being a female engineer: identity construction and resistance of women in engineering schools". Texas A&M University, 2006. http://hdl.handle.net/1969.1/4364.
Testo completoAbstract (sommario):
Compared to other professions, women's representation in engineering professions
is considerably lower than men's, and this particular situated-ness or locality makes women
experience a unique process of identity construction. Using qualitative methods - two
focus group meetings, nineteen autobiographical essays, and twenty two individual
interviews, this research focuses on what women learn from their experiences in
engineering school, and how they respond to their perceived experiences. This study
proposes to delineate (a) the dynamic interaction between women and the social structure
of engineering school; (b) women's perception and conceptualization of the social structure
they practice; and (c) women's strategic responses to the structure leading to identity
construction. Becoming an engineer is problematic for women because the identity of
"engineer" is based upon hegemonic ideas developed by previous generations of engineers
- men. This research explores how women, standing in the borderline of being women and being engineers, account and construct their identities as women engineers. Sometimes
women are subtly or not subtly coerced; sometimes they embrace dominant ideas;
sometimes they creatively resist dominant approaches.
28
Schley, Jeremiah P. "Single Cell Culture Wells (SiCCWells)". The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1406292709.
Testo completo
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Sivathanu, Vivek. "In vitro models for airway epithelial cell culture". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/81726.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 40-41).
This work is about the development of a physiologically relevant model of the human airway. Various factors such as the cell model, physiochemical factors such as the cell substrate properties including its stiffness, shear stress, stretch, the air-liquid interface and the biochemical factors in the medium influence the biology of the cells. The aim of this work is to closely approximate conditions in an in vivo situation by engineering the above conditions in to the in vitro platform. An assay to introduce the cell substrate properties was developed in a glass bottomed petri dish type culture as well as a microfluidic device culture. The influence of the cell substrate on airway epithelial cell monolayer formation was investigated in detail by changing the stiffness of the substrate independently by changing the gel concentration, the gel formation pH and the height of the gel from a hard substrate. Further, we found that biochemical growth factors have a huge role in cell monolayer formation. A real-time measurement of monolayer integrity using electrical resistance measurements was developed. A shear stress application platform was developed and a stretch application platform was designed. The applications of such a platform with the inclusion of various physiologically relevant factors include the study of physiologic evolution of microbes such as the influenza virus.
by Vivek Sivathanu.
S.M.
30
Aunins, John Grant. "Induced flocculation of animal cells in suspension culture". Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14330.
Testo completo
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Zhang, Xiaowei. "Orbitally shaken bioreactors for mammalian cell culture : engineering characterization and bioprocess scale-up /". [S.l.] : [s.n.], 2009. http://library.epfl.ch/theses/?nr=4492.
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March, John Clifton. "Metabolic engineering of eukaryotic signal transduction in Drosophila Schneider 2 (S2) cell culture". College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/2450.
Testo completoAbstract (sommario):
Thesis (Ph. D.) -- University of Maryland, College Park, 2005.Thesis research directed by: Chemical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
33
Damen, Bas Stefaan, e bsdamen@hotmail com. "Design, Development, and Optimisation of a Culture Vessel System for Tissue Engineering Applications". Swinburne University of Technology. n/a, 2003. http://adt.lib.swin.edu.au./public/adt-VSWT20040512.125051.
Testo completoAbstract (sommario):
A Tissue Engineering (TE) approach to heart valve replacement has the aim of producing an implant that is identical to healthy tissue in morphology, function and immune recognition. The aim is to harvest tissue from a patient, establish cells in culture from this tissue and then use these cells to grow a new tissue in a desired shape for the implant. The scaffold material that supports the growth of cells into a desired shape may be composed of a biodegradable polymer that degrades over time, so that the final engineered implant is composed entirely of living tissue. The approach used at Swinburne University was to induce the desired mechanical and functional properties of tissue and is to be developed in an environment subjected to flow stresses that mimicked the haemodynamic forces that natural tissue experiences. The full attainment of natural biomechanical and morphological properties of a TE structure has not as yet been demonstrated.
In this thesis a review of Tissue Engineering of Heart Valves (TEHVs) is presented followed by an assessment of biocompatible materials currently used for TEHVs. The thrust of the work was the design and development of a Bioreactor (BR) system, capable of simulating the corresponding haemodynamic forces in vitro so that long-term cultivation of TEHVs and/or other structures can be mimicked. A full description of the developed BR and the verification of its functionality under various physiological conditions using Laser Doppler Anemometry (LDA) are given. An analysis of the fluid flow and shear stress forces in and around a heart valve scaffold is also provided.
Finally, preliminary results related to a fabricated aortic TEHV-scaffold and the developed cell culture systems are presented and discussed. Attempts to establish viable cell lines from ovine cardiac tissue are also reported.
34
Hammond, John Stotesbury. "Scaffolds for liver tissue engineering : in vitro co-culture & in vivo release". Thesis, University of Nottingham, 2009. http://eprints.nottingham.ac.uk/12556/.
Testo completoAbstract (sommario):
This thesis presents the development and evaluation of two applications for scaffolds in the field of liver tissue engineering. In the first study a poly (D,L lactic acid) (PDLLA) scaffold is used as a three-dimensional template for hepatocyte–hepatic stellate cell (HSC) co-culture. To enhance PDLLA ligand binding capacity scaffolds are surface modified using allylamine plasma deposition and treatment with NaOH. Primary adult rat hepatocytes and HSC are then seeded onto these scaffolds and cultured in static conditions. Scanning electron microscopy (SEM) is used to assess mono-culture and co-culture morphology whilst synthetic and cytochrome P450 function are measured using albumin and testosterone assays. The second study explores the potential for intrahepatic growth factor and extracellular matrix (ECM) delivery from a biodegradable polymer scaffold to promote liver growth and to enhance regeneration. The study is undertaken in rats. The scaffold design and implantation technique are first piloted in a short survival study. Hepatocyte growth factor (HGF), epidermal growth factor (EGF), fibroblast growth factor (FGF)1, FGF2 and liver derived ECM (L-ECM) are then loaded into poly(lactic-co-glycolic acid) (PLGA) + 5% poly(ethylene glycol) (PEG) scaffolds and implanted into normal and partially hepatectomised liver. Implant morphology is assessed by micro-CT reconstruction. Growth factor bioactivity and release are confirmed by in vitro profiling. Liver growth and volume redistribution are assessed by liver weight analysis. Parenchymal injury and function are quantified by measuring serum aspartate aminotransferase (AST) & bilirubin. 5-bromodeoxyuridine (BrdU) inclusion & MIB-5 immunohistochemistry (IHC) are used to identify hepatocyte and non-parenchymal cell proliferation. Liver-scaffold interaction is characterised by H&E and Masson’s trichrome staining. Non-parenchymal cell migration is assessed by ED-1 and desmin IHC. All histology is then subjected to image analysis.
35
Li, Sisi. "Gel-embossing and electrospinning of biopolymers for cell culture and tissue engineering studies". Paris 6, 2013. http://www.theses.fr/2013PA066279.
Testo completoAbstract (sommario):
Ce travail de thèse vise à explorer des techniques de nanofabrication pour produire des substrats de culture et des matrices de génie tissulaire, basant sur une nouvelle approche biomimétique. Nous avons d’abord développé une nouvelle technique de moulage pour répliquer des nanostructures dans une couche de gélatine. Les motifs micrométriques peuvent être plus facilement obtenus par moulage assisté par aspiration. A plus large échelle, des matrices de trous à travers peuvent être percés dans une couche mince de gélatine en utilisant une machine-outil à commande numérique par ordinateur le tout étant biocompatible pour les études de culture cellulaire. Par la suite, nous avons appliqué une technique électrofilature pour produire des substrats de nanofibres de gélatine pour l'expansion à long terme de cellules souches pluripotentes humaines induites (hiPSCs). Pour montrer l'importance de la morphologie quasi tridimensionnelle des substrats de fibres, les empreintes de fibres en positive et négative ont été obtenus, montrant une corrélation évidente entre la qualité des hiPSCs après l'expansion à long terme et la morphologie de la surface du substrat. Enfin, nous avons fabriqué des nanofibres alignés en PLGA et montré leur supériorité pour la formation de feuille cellulaire en utilisant des cellules cardiaques dérivées d’hiPSCsThis thesis work aimed at exploring nanofabrication techniques to manufacture new types of cell culture substrates and scaffolds for tissue engineering based on a biomimetic approach. Firstly, we demonstrated a gel-embossing technique to replicate nanoscale patterns into gelatin layers. For microscale patterns, aspirationassisted gel-molding could be applied. For patterns of larger feature sizes, through-hole arrays could be punched in thin gelatin layers using a computer-aided mechanical machine, all being biocompatible for cell culture studies. Afterward, we applied an electrospinning technique to produce gelatin nanofibre substrates for long term expansion of human induced pluripotent stem cells (hiPSCs). To show the importance of quasi-three dimensional morphology of the fiber substrates, both positive and negative nanofibres imprints were produced, showing a clear correlation between the quality of the hiPSCs after long-term expansion and the surface morphology of the substrate. Finally, we fabricated PLGA aligned nanofibres and showed their superiority for cell sheet formation using hiPSCs cardiac cells
36
Gibbs, Margaret Joan. "Genetic engineering of the forage legume Lotus corniculatus using Agrobacterium : mediated transformation systems". Thesis, Durham University, 1991. http://etheses.dur.ac.uk/6040/.
Testo completoAbstract (sommario):
Gene transfer vectors based on the Agrobacterium tumefaciens Ti plasmid were used to develop a successful disarmed Agrobacterium tumefaciens-mediated transformation method for Lotus comiculatus. A binary vector construct, pJIT73, was used during the development of the Agrobacterium tumefaciens transformation system due to its selectable (Aph IV, nos- neo) and scorable markers. The effects of the antibiotics geneticin (G-418) and hygromycin B were studied. Use of kill curves and selection delay experiments allowed potentially suitable selection pressure parameters to be proposed. Using such selection during transformation experiments led to further optimisation of this stage of transformation. The influence of plant hormones on the regeneration of Lotus comiculatus explants was investigated and a modification of an established protocol using leaf explants was introduced as an attempt to reduce the overall time of regeneration. Various explants were used but leaf pieces were chosen as the most suitable explant on which to focus research. So, through alteration of various stages, including length of cocultivation and subsequent decontamination within the transformation process, a successful method was developed. Experiments indicated the optimum Agrobacterium tumefaciens strain to be used with Lotus comiculatus was the disarmed Ach5 type, LBA4404(pAL4404). Transgenic Lotus comiculatus plants were produced which expressed the scorable marker β-Glucuronidase gene (GUS) and the selectable marker for hygromycin B resistance, AphIV. Gene transfer was confirmed by Southern blotting. The new Agrobacterium tumefaciens-mediated vector system was used to introduce the cowpea trypsin inhibitor gene (CpTi) into Lotus comiculatus. However, although there was evidence for transformed callus development, no shoots were induced. By the use of previously established Agrobacterium rhizogenes-mediated system, an attempt was made to introduce the pea lectin gene (psl) into Lotus corniculatus. Hairy root regenerants were produced but genetic transfer was unconfirmed and attempted investigation of the plant - Rhizobium symbiosis involving Lotus corniculatus was not fulfilled.
37
Johnstone, Alex. "Microfluidic systems for neuronal cell culture". Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/37822/.
Testo completoAbstract (sommario):
At a high level of abstraction, the brain is a system for analysing sensory information, and responding appropriately. That information is encoded and stored in the millions of neural circuits that comprise the brain. Deciphering this code is essential to understanding how memories are implemented in physiologically normal brain tissue, and to inferring the nature of some neurological disorders affecting memory such as Alzheimer’s disease, in which the neural encoding is aberrant or unsuccessful. One approach to this problem is to reduce the complexity of the brain functionality to three elements: stimuli, response, and reinforcement. The electrical activity of individual neurons can be recorded with electrodes, capturing the pathways of signal propagation in a network of cells. Individual neurons can be also induced to reliably respond to electrical or optical stimuli, so that they initiate, relay, or even block a signal. If the stimuli to a finite network of cells can be made heterogeneous so that only a sub-population of cells is targeted, then the network can be trained to react in a repeatable way to a given stimulus, testing the concept that the higher order functions of the brain can emerge from a simple set of underlying computational rules. Training however requires a mechanism for reinforcing only some of the possible pathways, in synchrony with stimuli and in response to the recorded network activity. In the intact brain, this mechanism is pharmacological: a neuromodulator such as dopamine is released throughout the brain, but as it only coincides with some but not all neuronal activity, the reinforcement is temporally selective. The key task of this project is to emulate this selective neuromodulator reinforcement in vitro in a finite neuronal network. The project must also provide capacity for heterogeneous stimulation and individual cell recording, which can be coordinated with the reinforcement under computer control. The strategy used was to develop microscale chambers to house a small network of cultured neurons. The chambers were integrated with existing cell recording and stimulating technologies, so that specific connections between neurons could be both monitored and induced. Neuronal cultures of a few hundred cells were successfully grown in microchannels, on substrates capable of recording their electrical activity. Thus it was possible to create a small cultured network in which complete network activity could be detected, subject to a sufficiently precise recording technique. Additionally, a fluid-handling system was developed in order to emulate the continual replenishment of nutrients and soluble gases that are essential to cell survival. The system is intended to deliver soluble chemicals that modulate neuronal activity, on a timescale that is consistent with neuromodulator delivery in the body. The fluid handling system comprises a set of pressure driven pumps under automated computer control. This system has the capacity to deliver neuromodulator in solution with high spatiotemporal precision. The ability to reliably deliver and wash off precise volumes of drugs in a matter of seconds, with no dilution of the intended concentration, will be of great benefit to researchers investigating the response of various cell types to different agonists.
38
Varner, Johanna (Johanna M. ). "A microfluidic platform for three-dimensional neuron culture". Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/39919.
Testo completoAbstract (sommario):
Thesis (M. Eng.)--Massachusetts Institute of Technology, Biological Engineering Division, 2007.Includes bibliographical references (p. 51-53).
Neurodegenerative diseases typically affect a limited number of specific neuronal subtypes, and the death of these neurons causes permanent loss of a specific motor function. Efforts to restore function would require regenerating the affected cells, but progress is limited by a narrow understanding of the mechanisms that underlie the generation of these neurons from their progenitor cells. In order to prevent neuronal degeneration and potentially repair or regenerate the damaged motor output circuitry, it will be necessary to understand the molecular and genetic factors that control, direct, and enhance differentiation, axonal projection and connectivity. While techniques are available to separate specific populations of neurons once they are fully-differentiated, current methods make it nearly impossible to monitor or control the development of a neural precursor in standard open culture. To carry out directed differentiation experiments effectively, it will be critical to control how signals are introduced to the cells. In this study, we present a microfluidic system to address the limitations of previous research.
(cont.) The device is capable of generating a controlled gradient of chemoattractant or growth factor of interest and directing axonal growth through an extra-cellular matrix material. Once the cells have grown into the device, signals and gradients can be applied directly to either the cell bodies or the axons. This device will serve as a platform technology for future experimentation with biomaterial scaffolds for neural tissue engineering, drug design or testing, and eventually directed differentiation of neural precursor cells.
by Johanna Varner.
M.Eng.
39
Garber-Goldsman, Cheryl. "Studies of a central noradrenergic system in tissue culture". Thesis, University of Ottawa (Canada), 1985. http://hdl.handle.net/10393/4981.
Testo completo
40
Perry, Steven D. (Steven David). "Packed fiber bed reactor design for animal cell culture". Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/17220.
Testo completo
41
Kim, Ernest S. (Ernest Soonho) 1974. "Design of a single capillary-parenchymal co-culture bioreactor". Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/89889.
Testo completo
42
Avgoustiniatos, Efstathios S. "Oxygen diffusion limitations in pancreatic islet culture and immunoisolation". Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/8269.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2002.Includes bibliographical references.
Data for oxygen consumption by rat islets of Langerhans in a batch microreactor were fitted using a numerical solution of the transient oxygen diffusion-reaction equation. Average best-fit values were 3.1 +/- 0.7 x 10-8 mol/cm3-s for the maximum oxygen consumption rate Vmax in aminoacid-free media and 1.2 +/- 0.4 x 10-14 mol/cm-mm Hg-s for the oxygen permeability in islet tissue. These parameter values, along with a 30-60% positive correction for the presence of aminoacids in Vmax, were used to predict oxygen profiles inside and around islets under perifusion, culture, and immunoisolation conditions. The difference between Michaelis-Menten and zero-order kinetics and the role of the necrosis process in modeling of oxygen profiles were found to increase with the severity of hypoxia. Internal and external diffusion limitations were characterized for homogeneously dispersed tissue. Oxygen profiles were determined with finite differences in perifused rat islets for which second-phase insulin secretion data were available. Data were fitted with ad hoc kinetic models describing the effect of local pO2 on insulin secretion. A two-step, one-parameter model that assumed that local insulin secretion rate as a function of local pO2 is first-order for pO2 < P and zero-order for PO2 > P* resulted in the best data fit for P* values between 2 and 10 mm Hg, depending on the value of Vmax used. Oxygen profiles were estimated with finite elements for the axi-symmetric problem of single islet culture and the model did an excellent job in predicting loss of viability data, obtained using Trypan blue staining,
(cont.) as a function of islet diameter both under normoxic (ambient pO2 = 142 mm Hg) and hypoxic (40 mm Hg) conditions. The model was extended to massive islet culture and the effects of islet surface density and medium depth on viability were characterized and suggestions were made for the improvement of porcine islet culture conditions. In bioartificial pancreas devices we found that there is an optimal islet surface density (NS)opt for which insulin secretion rate is maximized, while secretory efficiency decreases monotonically with tissue density above a critical value. The design tissue density must be chosen in the range between this critical value and (Ns)opt' and its value depends on whether minimization of the device size or the amount of loaded tissue is more important.
by Efstathios Spyridon Avgoustiniatos.
Ph.D.
43
Surampudi, Vasudha. "POLYSACCHARIDE-BASED SHEAR THINNING HYDROGELS FOR THREE-DIMENSIONAL CELL CULTURE". VCU Scholars Compass, 2015. http://scholarscompass.vcu.edu/etd/3872.
Testo completoAbstract (sommario):
The recreation of the complicated tissue microenvironment is essential to reduce the gap between in vitro and in vivo research. Polysaccharide-based hydrogels form excellent scaffolds to allow for three-dimensional cell culture owing to the favorable properties such as capability to absorb large amount of water when immersed in biological fluids, ability to form “smart hydrogels” by being shear-thinning and thixotropic, and eliciting minimum immunological response from the host. In this study, the biodegradable shear-thinning polysaccharide, gellan-gum based hydrogel was investigated for the conditions and concentrations in which it can be applied for the adhesion, propagation and assembly of different mammalian cell types in an unmodified state, at physiological conditions of temperature. Cell studies, to show successful propagation and assembly into three-dimensional structures, were performed in the range of hydrogels which were deemed to be optimum for cell culture and the cell types were chosen to represent each embryonic germ layer, i.e., human neural stem cells for ectoderm, human brain microvasculature cells for mesoderm, and murine β-cells for endoderm, along with a pluripotent cell line of human induced pluripotent stem cells, derived from human foreskin fibroblasts. Three-dimensional cell organoid models, to allow for gellan gum based bioprinting, were also developed using human induced pluripotent stem cells and human neural stem cells.
44
Droz, PennElys. "Biocultural Engineering Design for Indigenous Community Resilience". Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/323449.
Testo completoAbstract (sommario):
Indigenous peoples worldwide are engaged in the process of rebuilding and re-empowering their communities. They are faced with challenges emerging from a history of physical, spiritual, emotional, and economic colonization, challenges including a degraded resource base, lack of infrastructure, and consistent pressure on their land tenure and ways of life. These communities, however, continue demonstrating profound resilience in the midst of these challenges; working to re-empower and provide for the contemporary needs of their people in a manner grounded in supporting bio-cultural integrity; the interconnected relationship of people and homeland. At the same time, in response to contemporary environmental degradation, the fields of resilience science, adaptive management, and ecological engineering have emerged, the recommendations of which bear remarkable similarity to Indigenous ontologies, epistemologies, and governance structures. The relationship between these fields and Indigenous epistemology, underscored by experience in the field, has led to the conceptualization of bio-cultural engineering design; design that emerges from the inter-relationship of people and ecology. The biocultural engineering design methodology identifies the unique cosmological relationships and cultural underpinnings of contemporary Indigenous communities, and applies this specific cultural lens to engineered design and architecture. The development of resilience principles within the fields of architecture and engineering have created avenues for biocultural design to be translatable into engineering and architectural design documents, allowing access to large scale financial support for community development. This method is explored herein through literature and analysis of practical application in several different Indigenous communities and nations. This method lends itself to future research on biocultural design processes as a source of technological and design innovation as Indigenous communities practice placing their values and cosmologies at the center of development decisions, as well as comprehensive start-to-finish documentation of the methodology applied to diverse engineered applications, including water systems, energy systems, and building construction.
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Franzén, Thobias. "Participatory culture in museums". Thesis, Malmö högskola, Fakulteten för kultur och samhälle (KS), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-22336.
Testo completoAbstract (sommario):
In 2012 library and museum professionals from 24 different countries met in Salzburg, Austria for the Salzburg Global Seminar. The seminar was entitled Libraries and Museums in an Era of Participatory Culture. Shortly summarised their views of participatory culture includes low barriers for engagement, strong support for creating, sharing and feeling a social connection with each other. During the seminar it was mentioned that participatory culture usually exists online and that their challenge was in creating experiences that work both online and offline and allow for meaningful participation.Contemporary examples of museums working with participatory culture to engage their visitors is presented. Inspired by these examples and working with research through design as main method technology experiments and prototypes are conducted to develop a concept. Findings from this iterative process leads to a final concept that has the potential to engage museum visitors both online and offline. In one part of this concept museum visitors explores a narrative in a physical interactive exhibition. Visitors proxemic relations to objects and other people is used to trigger media and unfold the full story in a room. In the end of the prototype visitors are asked to write a physical postcard that is also published on a web page.The final concept presented can be scaled and customised to suit many different scenarios and context. When structuring the narratives clear instructions guiding visitors through the experience should be included. The people who were invited to try this prototype all created content and were curios to know what other people had written.
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Zion, Sara Miriam. "Isolation and characterization of an arsenite-oxidizing culture". Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/40156.
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Gorman, Sharon. "Peering into the culture of a civil engineering discipline and finding the white rabbit". Thesis, Northern Arizona University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3621094.
Testo completoAbstract (sommario):
The representation of female students and students of color within the civil engineering discipline has been relatively stagnant during the last thirty years. Leaky pipeline approaches attempt to provide measures or programs that try to reduce the exiting of female students or students of color without necessarily addressing the social complexities of the environment itself. This ethnographically informed case study provides an explanation of social complexities that may prevent female students and students of color from fully fitting inside their civil engineering discipline.
Specifically, this study explored how female students and students of color navigated their civil engineering discipline as juniors or seniors at a medium-sized public university in the United States Southwest. During 2013, five staff members (all female) and eight students—both male and female—were interviewed. In addition, the researcher observed two upper division classes for a month and half, three times a week. The researcher also observed public spaces inside the engineering building. Finally, the researcher reviewed and analyzed public websites, syllabi, degree progression plans, and newsletters to further support findings.
Using a Grounded Theory approach and informed by critical and post-structural feminist and race theory, the researcher adapted a Grounded Theory Paradigm Model (Strauss & Corbin, 1990) to expose contradictions for explaining the social complexities of the context. The researcher found that students who identified outside the dominant white male role saw nuances of the context because of their Border Identities. Border identities, which evolved as a result of students coming from a different ethnicity, community background, and gender, allowed contradictions to be exposed and examined. As a result, the researcher discovered that highly regulatory educational contexts such as a civil engineering discipline support rituals leading to professionalization of students (in this case, as future engineers). Professionalization, which espouses values of sameness as related to the individual, in fact penalizes "the different." Through the professionalization of students, values of hard work, productivity, meritocracy, and effort intend to homogenize the experience of civil engineering students across the board, despite differences of identity, in order to maintain and preserve the dominant white male context.
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Miller, Jonson William. "Citizen Soldiers and Professional Engineers: The Antebellum Engineering Culture of the Virginia Military Institute". Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/29135.
Testo completoAbstract (sommario):
The founders and officers of the Virginia Military Institute, one of the few American engineering schools in the antebellum period, embedded a particular engineering culture into the curriculum and discipline of the school. This occurred, in some cases, as a consequence of struggles by the elite of western Virginia to gain a greater share of political power in the commonwealth and by the officers of VMI for authority within the field of higher education. In other cases, the engineering culture was crafted as a deliberate strategy within the above struggles. Among the features embedded was the key feature of requiring the subordination of one’s own local and individual interests and identities (class, regional, denominational, etc.) to the service of the commonwealth and nation. This particular articulation of service meant the performance of “practical” and “useful” work of internal improvements for the development and defense of the commonwealth and the nation. The students learned and were to employ an engineering knowledge derived from fundamental physical and mathematical principles, as opposed to a craft knowledge learned on the job. To carry out such work and to even develop the capacity to subordinate their own interests, the cadets were disciplined into certain necessary traits, including moral character, industriousness, selfrestraint, self-discipline, and subordination to authority. To be an engineer was to be a particular kind of man. The above traits were predicated upon the engineers being white men, who, in a new “imagined fraternity” of equal white men, were innately independent, in contrast to white women and blacks, who were innately dependent. Having acquired a mathematically-intensive engineering education and the character necessary to perform engineering work, the graduates of VMI who became engineers were to enter their field as middle-class professionals who could claim an objective knowledge and a disinterested service to the commonwealth and nation, rather than to just their own career aspirations.Ph. D.
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Ma, Teng. "Fibrer-based bioreactor systems in Mammalian cell culture and tissue engineering Human Trophoblast cells /". The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488188894442926.
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Sjögren, Frida. "Microstructuring of Hyaluronic acid cell culture scaffolds". Licentiate thesis, Uppsala universitet, Mikrosystemteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-334653.
Testo completo