• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 67
  • 20
  • 11
  • 8
  • 2
  • 2
  • 2
  • Tagged with
  • 145
  • 34
  • 27
  • 18
  • 18
  • 16
  • 15
  • 14
  • 14
  • 12
  • 12
  • 12
  • 12
  • 11
  • 11
  • 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 high resolution study of surface reactivity by scanning electrochemical microscopy

Andrews, Lynn Marie January 1997 (has links)
No description available.
2

Microelectrode studies of the electrochemistry of the lead-acid battery system

Li, L. J. January 1987 (has links)
No description available.
3

Development of a sulfate microelectrode for profiling environmental biofilms

Ren, Shujie Unknown Date
No description available.
4

A.C. electrokinetic bioassays : development of electrorotation assay for analytes in water

Goater, Andrew David January 1999 (has links)
The work described is primarily concerned with the understanding of the induced AC electrokinetic properties of the transmissive stages of two genera of waterborne protozoan pathogens, namely Cryptosporidium and Giardia. The assessment of viability through the use of electrorotation (ROT) has been investigated in comparison with conventional techniques. The optimum conditions for detennining C. parvum viability using ROT are described and discussed. Two Giardia and three Cryptosporidium species were investigated, as were a total of ten Cryptosporidium parvum isolates. With all species investigated a good correlation was found between the ROT response of clean particles and conventional vital dye techniques. Adherent bacteria on the particles surface have been identified as a major problem for subsequent ROT analysis. This is the first description of the effect of adherent bacteria on the dielectric response of biological particles . . A novel single layer electrode array was designed and successfully tested to overcome the problems of low particle concentration, interfering debris and particle position in the electrorotational electrodes. The device was shown to selectively concentrate particles into a central region whereupon their physiological state was then assessed through their ROT response. Modification of the device enabled the isolation of one or more particles onto a membrane, providing a suitable collection method for low particle number handling. The clearest demonstration to date of the effect of membrane integrity on the ROT response is described from spectra obtained for an oocyst before and after excystation in vitro. Storage time effects for oocysts of C. baileyi are also described as are isolate differences for C. parvum oocysts which are apparent in the low frequency region of the spectra. The implications of these results to the water industry and potential diagnostic applications of electrorotation are discussed.
5

A SYSTEM FOR TESTING OF MICROELECTRODE SENSORS

DAS, ANGAN January 2005 (has links)
No description available.
6

Superoxide anion in osteoclast and osteoblast function

Berger, Christine Elizabeth Marie January 1998 (has links)
No description available.
7

XUROGRAPHIC MICROWIRE INTEGRATION TECHNIQUE FOR LAB ON CHIP APPLICATIONS

Liu, Juncong January 2017 (has links)
Many functions in a lab-on-a-chip device such as heating, electrochemical sensing and electrophoresis require integration of microelectrodes. However, conventional techniques for microelectrode integration are either requiring expensive facilities, cleanroom environment or insufficient in resolution and microelectrode thickness. Microwires have also been integrated into LOC devices as microelectrodes. They are commercially available in a diversity of material. and diameter, with industrial production standard and mechanical strength comparable to bulk metal, which make them ideal candidate for microelectrode. Nonetheless a technique to integrate these microwires into complicated microelectrode patterns has not yet been developed. In this thesis, two microwire integration techniques based on xurography are developed for elastomer and rigid polymer. Copper, silver, platinum, carbon and Ni-Cr alloy microwires down to 15 µm with minimum spacing of 150 µm and controllable position in the height direction are successfully integrated. The microwire electrode can also be suspended in the middle of the microchannel with desired length and angle. Various applications are presented to demonstrate the versatility of the xurographic microwire integration process. / Thesis / Master of Applied Science (MASc)
8

AZO DYE BIODEGRADATION AND INHIBITION EFFECTS ON AEROBIC NITRIFICATION AND ANOXIC DENITRIFICATION PROCESSES

LI, JIN 03 December 2001 (has links)
No description available.
9

MICROELECTRODE ARRAY STUDIES OF NORMAL AND DISEASE-ALTERED L-GLUTAMATE REGULATION IN THE MAMMALIAN CENTRAL NERVOUS SYSTEM

Day, Brian Keith 01 January 2005 (has links)
L-glutamate (Glu) is the major excitatory neurotransmitter in the mammalian central nervous system. Monitoring extracellular Glu is critical to understanding Glu regulation to discriminate physiological and pathological roles. To overcome the limitations of previous in vivo extracellular Glu studies, we developed Glu selective microelectrode arrays with better spatial and temporal resolutions than commonly used techniques like microdialysis. We used these microelectrode arrays to characterize basal and potassium-evoked Glu neurotransmission in the normal rat brain. We then investigated disease-related Glu alterations in a rat model of Parkinson's disease and normal Glu regulation in young and aged rhesus monkeys. In the normal anesthetized rat striatum and frontal cortex, basal Glu was regulated by active release and uptake mechanisms, fully TTX-dependent, and measured at ~2 micromolar levels. Potassium-evoked Glu kinetics were fast, concentration-dependent, and rapidly reproducible at 15-20 seconds intervals. In the unilateral 6-hydroxydopamine-lesioned rat, there were significant bilateral increases in potassium-evoked Glu release in the striatum and frontal cortex compared to hemisphere-matched non-lesioned rats. Ipsilateral striatal effects may have been related to DA loss, while contralateral striatal effects and the bilateral frontal corticaleffects may have resulted from parkinsonian neurotransmitter changes or bilateral neuranatomical connectivity, especially in the cortex. There were also alterations in Glu kinetics in the nucleus accumbens in both non-lesioned and lesioned rats. With appropriate technological and methodological modifications, we successfully recorded normal Glu signaling in anesthetized nonhuman primates in the operating room. Fast potassium-evoked Glu signals were recorded in the motor cortex of all monkeys, and Glu ejections showed robust Glu uptake in the motor and frontal cortices of all monkeys. These findings are comparable to initial rat studies. Slow evoked Glu kinetics and high basal Glu levels with oscillatory behavior were recorded in the frontal cortex. The primary age-related differences between monkeys were the nearly ten-fold increases in the volumes of Glu ejected needed in the aged monkey to achieve amplitude-matched signals in the motor and frontal cortices and a decreased uptake rate in the motor cortex. Preliminary work with excised human tissue and future plans for patient-oriented research and clinical applications are discussed.
10

The Design and Evaluation of Microelectrode Patterns on a Multilayer Biochip Platform for Trapping Single Cells using Dielectrophoresis

Ibrahim, Siti Noorjannah January 2012 (has links)
Trapping ability on a biochip device is useful for systematic cell addressing and real-time observation of single cells analysis, however, precise control over the cell movements remains challenging. This thesis addresses the problem of controlling movement of single cells on a biochip platform by a technique called the Dielectrophoretic (DEP) force. Existing researches showed that the DEP force offers precise control of cell movements through various microelectrode designs which generate strong polarization effects i.e., DEP forces, but with the expense of damaging cell’s structure. The thesis contribute three new microelectrode designs for trapping single cells: the dipole, the quadrupole and the adaptive octupole, structured on a metal-insulator-metal (multilayer) biochip platform called the Sandwiched Insulator with Back Contact (SIBC) biochip. Cores of the study lie on the microelectrode designs that are capable of generating strong DEP holding forces, the back contact to enhance trapping of single cells and the fabrication process of creating a metal-insulator-metal structure. This thesis also presents details on the experimental setups of the trapping experiments and the numerical analysis of the microelectrode designs. The SIBC biochip comprises of the back contact on the first metal layer, the microcavity (cell trap) on the insulator layer and the three microelectrodes on the second metal layer. Together, the three microelectrodes and the back contact generate DEP forces that attract particles/single cells toward microcavities and maintain their positioning in the traps. Prior to the fabrication, profiles of the DEP force generated by the microelectrodes are studied using COMSOL3.5a software. Simulation results suggest that the DEP trapping region can be created surrounding the microcavity if the microelectrode and the back contact are connected with AC signals that have different phases. The strongest DEP force can be obtained by setting the back contact and the microelectrodes with AC signals that have 180 degree phase difference. Evaluations on the trapping functionality for the three microelectrodes were conducted using polystyrene microbeads and Ishikawa cancer cells line suspended in various medium. Trapping capability of the three microelectrodes was demonstrated through experiments with 22 percent of the Ishikawa cancer cells and 17 percent of the polystyrene microbeads were successfully trapped. With these promising results, the new microelectrode designs together with the SIBC biochip structure have huge potentials for biomedical applications particularly in the field of diagnosis and identification of diseases.

Page generated in 0.0635 seconds