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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

A study of bubble generation and hydrodynamics in dissolved air flotation

Repanas, Konstantinos January 1992 (has links)
In Dissolved Air Flotation the performance of the saturator and subsequent release of the air from the solution is important. In particular the bubble size, the degree of saturation and the hydrodynamic bubble movement are important physical parameters. In this study all these have been investigated. The factors affecting the bubble size when gas is released from a supersaturated solution and the performance of two types of absorbers a conventional packed column and a Higee Absorber were examined. The size of the bubbles generated from a nozzle have been measured in tap water at different operation conditions of liquid flowrate, gas flowrate and pressure. The bubble size was measured using a photographic technique and found to decrease with increasing the gas pressure in the conventional saturator, but it was not possible to observe the small bubbles generated using the Higee Technique. For the conventional device, the liquid flowrate had a significant role whereby the bubble diameter fell with flowrate. Bubble uniformity increased as both pressure and liquid throughput increased. The saturation performance of the two kinds of absorbers were examined. In all the cases, the Higee technique operate better as far the saturation level was concerned. The degree of saturation in the Higee systems was found to be a strong function of both gas and liquid flowrates as well as the rotational speed (which governs the gas pressure). Finally, as it may be possible to distribute the saturated solutions and (any bubbles formed) more uniformly throughout flotation tanks if Higee saturators are used, a computer package was adopted to provide enough data for the simulation of the flow patterns in flotation tanks.
2

Recycling isotachophoresis: A novel approach to preparative protein fractionation

Sloan, Jeffrey Edward, 1963- January 1987 (has links)
Electrophoresis is a widely used analytical technique in the medical and biotechnology industries. It can provide for the determination of thousands of individual compounds on this small scale. The operating conditions are quite conducive to use with the delicate products of genetic engineering. Due to other complexities associated with scale-up, the process is not widely used on a large scale. A novel recycling electrophoretic instrument was investigated as a preparative protein separation device. The process occurs in a thin film of liquid between two flat plates, in a direction perpendicular to the flow. This device was unique in its use of a relatively high flowrate, and recycling of the process fluid as a method for increasing residence time. The apparatus was operated in three modes, isoelectric focusing (IEF), zone electrophoresis (ZE) and isotachophoresis (ITP). For use in the ITP mode, a computer was used for data acquisition and control functions. Model systems included monoclonal antibodies and lentil lectins.
3

Sistema para medição de erro de planicidade / Flatness measurement system

Magalhães, Rita de Cássia Alves de 02 June 2006 (has links)
A acuracidade dos processos de medição e de montagem que utilizam os desempenos como referência depende principalmente da planicidade dessas superfícies. Se a referência está fora das especificações é inútil utilizar instrumentos sofisticados e de alta acuracidade. Neste trabalho é apresentado um sistema para medição de desvios de planicidade de desempenos. O sistema é constituído por dois transdutores de deslocamento do tipo LVDT fixados no eixo z de uma máquina de medir a três coordenadas (MM3C). Durante a medição a intenção é avaliar apenas os desvios da superfície, no entanto os mancais das MM3C não se deslocam perfeitamente e as leituras obtidas são as componentes dos desvios da superfície e do movimento dos mancais. Para eliminar os componentes de erros da máquina dos dados medidos, pode-se usar as técnicas de separação de erros, e então, o desvio da superfície pode ser determinado. O sistema de medição proposto possui uma interface eletrônica que possibilita a aquisição dos sinais da régua óptica da MM3C e dos transdutores de deslocamento do tipo LVDT. Possui, também, um programa computacional que utiliza as técnicas de separação de erros para determinar o desvio de planicidade do mensurando. O sistema desenvolvido foi utilizado para medir o desvio de planicidade de uma superfície. Para verificar a eficiência do mesmo foi realizada uma comparação entre os valores de erro de planicidade obtidos através de medição com o sistema proposto e aqueles obtidos com interferômetro a laser e nível eletrônico. / The accuracy of measurement and assembly process using surface plates depends mainly on these surfaces flatness. If the surface plate does not meet the flatness specification, it is ineffective to apply high technology instruments of measurement. This research proposes is to develop a flatness measurement system for surface plates using two electronic comparators attached to the coordinate measuring machine (CMM). During a measurement process, the purpose is to evaluate the workpiece profile. However, the signals picked up by sensors include the workpiece profile and component motion error. In order to separate these errors, error separation techniques can be applied. The proposed measurement system has an electronic interface to collect data from the CMM optical scale and from the electronic comparators. The collected data are sent to a computer prepared with an algorithm for applying the error separation equations and for compute the flatness error. A surface was measured using the proposed measurement system. To evaluate its efficiency, the results were compared to the measurements made using electronic level and laser interferometric system.
4

Sistema para medição de erro de planicidade / Flatness measurement system

Rita de Cássia Alves de Magalhães 02 June 2006 (has links)
A acuracidade dos processos de medição e de montagem que utilizam os desempenos como referência depende principalmente da planicidade dessas superfícies. Se a referência está fora das especificações é inútil utilizar instrumentos sofisticados e de alta acuracidade. Neste trabalho é apresentado um sistema para medição de desvios de planicidade de desempenos. O sistema é constituído por dois transdutores de deslocamento do tipo LVDT fixados no eixo z de uma máquina de medir a três coordenadas (MM3C). Durante a medição a intenção é avaliar apenas os desvios da superfície, no entanto os mancais das MM3C não se deslocam perfeitamente e as leituras obtidas são as componentes dos desvios da superfície e do movimento dos mancais. Para eliminar os componentes de erros da máquina dos dados medidos, pode-se usar as técnicas de separação de erros, e então, o desvio da superfície pode ser determinado. O sistema de medição proposto possui uma interface eletrônica que possibilita a aquisição dos sinais da régua óptica da MM3C e dos transdutores de deslocamento do tipo LVDT. Possui, também, um programa computacional que utiliza as técnicas de separação de erros para determinar o desvio de planicidade do mensurando. O sistema desenvolvido foi utilizado para medir o desvio de planicidade de uma superfície. Para verificar a eficiência do mesmo foi realizada uma comparação entre os valores de erro de planicidade obtidos através de medição com o sistema proposto e aqueles obtidos com interferômetro a laser e nível eletrônico. / The accuracy of measurement and assembly process using surface plates depends mainly on these surfaces flatness. If the surface plate does not meet the flatness specification, it is ineffective to apply high technology instruments of measurement. This research proposes is to develop a flatness measurement system for surface plates using two electronic comparators attached to the coordinate measuring machine (CMM). During a measurement process, the purpose is to evaluate the workpiece profile. However, the signals picked up by sensors include the workpiece profile and component motion error. In order to separate these errors, error separation techniques can be applied. The proposed measurement system has an electronic interface to collect data from the CMM optical scale and from the electronic comparators. The collected data are sent to a computer prepared with an algorithm for applying the error separation equations and for compute the flatness error. A surface was measured using the proposed measurement system. To evaluate its efficiency, the results were compared to the measurements made using electronic level and laser interferometric system.
5

Die Komponentenseparationstechnik – Analyse der klinischen Ergebnisse anhand einer systematischen Literaturübersicht und der Daten des deutschen Herniamed-Registers / Component Separation Technique - An analysis of the clinical results based on a systematic literature review and on the data of the German Herniamed Register

Thiessen, Andreas 30 March 2021 (has links)
No description available.
6

Review of magnetic bead surface markers for stem cell separation : Literature study for MAGic Bioprocessing

Holmberg, Gustav, Svensson, Adrian, Bergström, Erik, Westerberg, Leo, Wijitchakhorn, Watthachak January 2022 (has links)
Stem cell therapy and transplantation is a quickly evolving field with many clinical applications. However, several problems need to be overcome before they can be applied on an allogenic scale, and among them is ensuring of the purity of the applied differentiated stem cell culture. Separation using magnetic beads which attach to the wanted cells has proven to be an effective and easy method to separate them from a sample. An important factor with the method is the choice of specific surface antigens on the beads which determines how well the beads are attached to the cell.  This report will provide some fact of the immunotherapy and some of the most important stem cells and their differentiation to an active cell. It will be elucidated which cytokines are important for differentiation, and current clinical studies in the immunotherapeutic field of stem cells and their useful surface antigens. Furthermore, regenerative medicine using stem cells will be covered. A brief overview mesenchymal and induced pluripotent stem cells, their biological markers, and their various uses. Specific projects using regenerative medicine will be described and an overview of ever-expanding market for regenerative medicine will also be included.

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