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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.
41

Electrochemical determination of surface active compounds at noble metal ultramicroelectrodes in flowing solutions

Norouzi, Parviz 01 January 1999 (has links)
In this work, a new electrochemical detection method was developed with the ability to determine a wide range of inorganic and organic species at, trace levels. In brief, the detection method takes advantage of all possible electrochemical reactions that may occur during scanning of the electrode potential. Changes in the detector response are mainly the result of inhibition of oxygen adsorption and hydrogen adsorption, alteration of electrical properties of the double layer, or redox processes of the adsorbate. Various electrochemical techniques were examined in the measurements; i.e. cyclic voltammetry, pulse amperometric detection, and square wave voltammetry. In those electrochemical techniques, the detection was carried out in a stripping mode after accumulation of analytes on the electrode surface. The smallest discernable signal is associated with about 0.1% surface coverage, which corresponds to the adsorption of about 10-18 mol of analyte on a ultramicroelectrode 5-[mu]m in radius. The response time of the detector to the concentration change in most cases is less than 1s. Electrochemical conditioning of the working electrode is sufficient to ensure a stable response for a period of several hours. It appears that square wave and cyclic voltammetry techniques are more suitable for the detection method. The linear dynamic range of the calibration curve depends on the characteristic of the analyte-electrode bond and redox processes of the analyte, which may occur at the electrode surface. For instance, for strongly adsorbing molecules the linear dynamic range extends over two orders of magnitude from about 10 -7 M to 10-5 M and for electroactive compounds from about 10-8 M to 10-4 M. In general, the relative standard deviation for replicate determinations was lower than 5%. Moreover, in these analyses, removal of oxygen from the analyzed solutions is not required.
42

Novel immobilization chemistry for bioaffinity sensors /

Yan, Fei. January 2001 (has links)
Thesis (Ph. D.)--State University of New York at Binghamton, Chemistry Department, 2001. / Includes bibliographical references (leaves 209-237).
43

Measurements of halogen and peroxy radicals by chemical amplification

Mihele, Cristian M. January 1999 (has links)
Thesis (Ph. D.)--York University, 1999. Graduate Programme in Chemistry. / Typescript. Includes bibliographical references (leaves 151-163). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pNQ39292.
44

Smart microplates: integration of photodiode within micromachined silicon pyramidal cavity for detecting chemiluminescent reactions and methodology for passive RFID-type readout / Integration of photodiode within micromachined silicon pyramidal cavity for detecting chemiluminescent reactions and methodology for passive RFID-type readout

Park, Yoon Sok, 1977- 28 August 2008 (has links)
Since the late 1990s our group has been working with groups in chemistry department at the University of Texas at Austin on a project referred as "Electronic Taste Chip," a MicroElectroMechanical System (MEMS) based miniaturized microfluidic chemical sensor with multianalyte detection capabilities. By integrating optical detection mechanism directly onto the silicon chip a cost effective, compact, and portable sensor can be realized enabling use of these chips out of conventional laboratory environment. Addition to the integration a noble approach of accessing a photodiode with non-contact powerless RFID type readout is presented. By doing so a packaged photodiode can be interrogated without direct electrical contact, enhancing the portability even further for a sensor operated in aqueous medium. First background information regarding the project as well as design and integration criteria is presented followed by demonstration of non-contact RFID-type readout of a photodiode. Detailed discussion on the development of process integration scheme is discussed along with the measurements verifying the performance of the fabricated photodiode. During this investigation normally overlooked design criteria of collection efficiency, the effect of how a target element is to be delivered to a detection mechanism on the overall performance of the sensor, is addressed and discussed.
45

Chemical plume tracking : from virtuality to reality

Kikas, Timo 08 1900 (has links)
No description available.
46

Model-based design optimization of heterogeneous micro-reactors and chemical sensors

Phillips, Cynthia Michelle 08 1900 (has links)
No description available.
47

Smart microplates integration of photodiode within micromachined silicon pyramidal cavity for detecting chemiluminescent reactions and methodology for passive RFID-type readout /

Park, Yoon Sok. January 1900 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.
48

Chemical sensors for urea and organophosphate nerve agents

Cabrera, Sandra F. January 2006 (has links)
Thesis (Ph. D.)--University of Nevada, Reno, 2006. / "May, 2006." Includes bibliographical references. Online version available on the World Wide Web.
49

Imaging based sensor arrays /

Bronk, Karen Srour. January 1996 (has links)
Thesis (Ph.D.)--Tufts University, 1996. / Adviser: David R. Walt. Submitted to the Dept. of Chemistry. Includes bibliographical references. Access restricted to members of the Tufts University community. Also available via the World Wide Web;
50

Development of high-density optical fiber arrays : new designs and applications in microscopy, microfabrication and chemical sensing /

Michael, Karri L. January 1999 (has links)
Thesis (Ph.D.)--Tufts University, 1999. / Adviser: David R. Walt. Submitted to the Dept. of Chemistry. Includes bibliographical references (leaves 233-253). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

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