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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Thermally Stable Human Type 5 Adenovirus through Spray Drying: Storage Efficacy and Process Optimization

LeClair, Daniel January 2016 (has links)
This thesis investigates enhancing the thermal stabilization of a human type 5 adenoviral vector (AdHu5) through spray drying. The spray drying process was used to dry and effectively immobilize the AdHu5 within a mixture of carbohydrate or amino acid excipients into a powder form, resulting in significantly increased thermal stabilization of the viral vector. Spray dried powders were characterized by scanning electron microscopy, differential scanning calorimetry, Karl Fischer titrations, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) to identify the effects of temperature and atmospheric moisture on the immobilizing matrix. The best performing spray dried powder in terms of thermal stability consisted of an excipient blend of mannitol and dextran. Response surface methodology was employed to optimize production of these mannitol/dextran powders; measured responses were those relevant to industrial processing of a therapeutic material, namely powder yield for maximizing quantity, particle size for maximizing production of inhalation-deliverable powders, and adenoviral vector response for minimizing the loss of therapeutic activity. The spray drying process parameters of inlet temperature, spray gas flow rate, liquid feed rate and solute concentration in the feed were optimized resulting in a powder yield of 90%, percentage of ideally-sized particles of 50% and a near-zero viral vector titre loss of 0.25 log loss median tissue culture infectious dose (TCID50). The spray dried mannitol/dextran powders proved to have exceptional thermal stability during long term storage as minimal viral vector activity loss was observed when stored at 20°C for 90 days at low relative humidity (0.7 ± 0.3 log TCID50) in comparison to the liquid control which exhibited complete activity loss under the same storage conditions. Furthermore, viral activity of mannitol/dextran powders was retained over short term exposure (72 hours) to temperatures as high as 55°C whereas the liquid control expectedly lost all AdHu5 activity after 30 minutes. Overall, this work provides a guideline for the production of thermally stable powders and active biopharmaceuticals, such as AdHu5 vectors for vaccine applications, using the spray drying process. / Thesis / Master of Applied Science (MASc) / Many vaccines and their base components inherently deteriorate in function at moderate temperatures. Storage by refrigeration at temperatures ranging between 4°C and -80°C is the norm. Such refrigeration is costly for long term storage and significantly limits where vaccines can be sent. This reduces the availability of vaccines in locations around the world where these storage conditions are infeasible but vaccines are needed most. Spray drying, a process which forms dry powders from solution, was used; the solution contained sugars or amino acids to surround and protect the sensitive vaccine component. The produced powders from this work exhibited enhanced thermal stability compared to the control, reducing the need for refrigeration during storage and transport. The spray drying process was further optimized for industrial use by maximizing the amount of powder recovered and ensuring the particle size was appropriate for inhalable use, but most importantly, minimizing losses in therapeutic effectiveness during processing. This production of a thermally stable vaccine is advantageous because is allows for better world-wide accessibility and reduces overall production and delivery costs.
2

Polovodičové senzory plynů na bázi oxidu ciničitého / Tin dioxide based semiconducting gas sensors

Gablech, Imrich January 2014 (has links)
This project is aimed at semiconductive gas sensors based on tin dioxide. In the first part, gas sensors are divided depending on their principal of functionality. Next part is about functionality of tin dioxide gas sensors and the possibilities of active layer modification. Experimental describes gas sensor from its drawing until construction, testing and characterization. Several microelectronic technologies such as thin-film, thick-film, LTCC, spray-coating or wire-bonding were used for constructing the sensor. In the last part properties of gas sensors and differences in functionality between modified and unmodified gas sensor are summarized.
3

Разработка “интеллектуальных” систем термостабилизации подшипников шпиндельного узла металлорежущего станка в среде MATLAB : магистерская диссертация / Development of "intelligent" systems of thermal stabilization of bearings of the spindle Assembly of the metal-cutting machine in MATLAB

Гараев, Е. С., Garaev, E. S. January 2018 (has links)
The aim of the work is to develop systems of thermal stabilization of metal-cutting machine spindle assembly with artificial intelligence in MATLAB environment. The paper analyzes the existing systems of thermal stabilization of the supports of spindle units of metal-cutting machines and the known methods of compensation of thermal deformations of machines that occur during machining. The advantages and disadvantages of such systems are shown and attention is drawn to the thermal stabilization systems based on fuzzy logic. Two new variants of such systems are considered, which realize control on deviation and combined (on deviation and disturbance). Both systems are implemented programmatically in MATLAB. According to the results of programs in MATLAB, a scientific article was written, which in the international competition US-2017-02 took 3rd place in the direction of “Technical Sciences” in the category “Research project”. Diploma for 3rd place and the text of the article from the collection are attached. The explanatory note to the project contains 153 sheets and is accompanied by 23 demonstration sheets. / Цель работы – разработка “интеллектуальных” систем термостабилизации шпиндельного узла металлорежущего станка с искусственным интеллектом в среде MATLAB. В работе анализируются существующие системы термостабилизации опор шпиндельных узлов металлорежущих станков и известные способы компенсации тепловых деформаций станков, возникающих при обработке резанием. Показываются достоинства и недостатки таких систем и обращается внимание на системы термостабилизации, построенные на основе нечеткой логики. Рассматриваются два новых варианта таких систем, которые разработаны аппаратно и реализующие управление по отклонению и комбинированное (по отклонению и возмущению). Обе системы реализуются программно в MATLAB. По результатам создания программ в MATLAB, была написана научная статья, которая в международном конкурсе US-2017-02 заняла 3-е место по направлению “Технические науки” в номинации “Исследовательский проект”. Диплом за 3-е место и текст статьи из сборника прикреплены в приложении. Пояснительная записка к проекту содержит 153 листа и сопровождается 23 демонстрационными листами.
4

Разработка технических средств уменьшения температурных погрешностей обработки на высокоскоростных токарных станках : магистерская диссертация / Development of technical means to reduce the temperature errors of processing on high-speed lathes

Оссовская, Е. С., Ossovskaya, E. S. January 2021 (has links)
В начале работы рассматриваются факторы, которые влияют на точность станков, и учитывается роль температурных деформаций для обеспечения точности обработки на металлорежущих станках. Наблюдается, что большое влияние на точность станков оказывают тепловые деформации. После этого познакомились со способами уменьшения температурных деформаций узлов станков, которые используются в данное время, и с техническими средствами их реализации. Рассмотрев существующие системы, мы определили задачу разработки системы термостабилизации с водяным охлаждением электрошпинделя. Для начала мы модернизировали существующую систему термостабилизации шпиндельного узла, в которую включили цепь дифференциала. Потом, обозначив достоинства и целесообразность комбинированного управления, разработали более совершенную систему термостабилизации шпиндельного узла. Далее рассмотрен другой фактор погрешности при обработке – это инструмент, в нашем случае резец для токарной обработки. Для него была разработана система охлаждения с учетом нагрева пластины. / At the beginning of the work, the factors that affect the accuracy of machine tools are considered, and the role of temperature deformations is taken into account to ensure the accuracy of processing on metal-cutting machines. It is observed that thermal deformations have a great influence on the accuracy of machine tools. After that, we got acquainted with the ways to reduce the temperature deformations of machine components that are currently used, and with the technical means of their implementation. Having considered the existing systems, we determined the task of developing a thermal stabilization system with a water-cooled electric spindle. To begin with, we upgraded the existing thermal stabilization system of the spindle assembly, which included a differential circuit. Then, having identified the advantages and expediency of combined control, we developed a more advanced system of thermal stabilization of the spindle assembly. Next, another factor of error in processing is considered – this is a tool, in our case, a cutter for turning. A cooling system was developed for it, taking into account the heating of the plate.

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