Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2004. / Accompanying CD-ROM contains supporting information on avi formated video clips. Includes bibliographical references (leaves 172-183). Also available in electronic version. Access restricted to campus users.

Arguments for miniaturization of a thermal field-flow fractionation system ( and #956;-ThFFF) and fabrication of a micro-scale acoustic field-flow fractionation system ( and #956;-AcFFF) using similar methods was presented. Motivation for miniaturization of ThFFF systems was established by examining the geometrical scaling of the fundamental ThFFF theory. Miniaturization of conventional macro-scale ThFFF systems was made possible through utilization of micromachining technologies. Fabrication of the and #956;-ThFFF system was discussed in detail. The and #956;-ThFFF system was characterized for plate height versus flow rate, single component polystyrene retention, and multi-component polystyrene separations. Retention, thermal diffusion coefficients, and maximum diameter-based selectivity values were extracted from separation data and found comparable with macro-scale ThFFF system results. Retention values ranged from 0.33 to 0.46. Thermal diffusion coefficients were between 3.0ױ0-8 and 5.4ױ0-8 cm2/sec?? The maximum diameter-based selectivity was 1.40. While the concept of an acoustic FFF sub-technique has been around for decades, the fabrication methods have not been available until recently. The theory was developed in full including relating sample physical properties to retention time in the FFF system. In addition to the theory, the design and fabrication of the and #956;-AcFFF was presented. Design results from an acoustic modeling program were presented with the determination of the acoustic resonant frequency. The acoustic-based systems was designed around the model results and characterized by electrical input impedance, fluidic, plate height, polystyrene suspension retention, and polystyrene mixture separation studies. The and #956;-AcFFF system was able to retain a series of nanometer scale polystyrene samples. However, the retention data did not follow normal mode retention but did reveal the location of the steric inversion point for the power level used, around 200 nm. The results of the multiple component separation confirmed this results as the sample, which contained 110, 210, and 300 nm diameter samples, was not resolved but only broadened.

The objective of this research was to develop efficient, non-invasive separation systems for various biological and non-biological substances. One of the major technological pushes in modern bioanalysis instrumentation development is the realization of efficient, miniaturized bioanalysis systems. In this work, three sizes of micromachined electrical field-flow fractionation (m-ElFFF) systems, with complementary on-column electrical and optical detection modalities were fabricated to achieve this objective. Field-flow fractionation (FFF) technology is capable of fractionating (or separating) a wide variety of materials and is capable of hundreds of consecutive analysis runs using a single system. A highly promising sub-technique, particularly for the analysis of biological / biochemical materials, is electrical field-flow fractionation (ElFFF). In this work, microfabrication technologies were used to fabricate m-ElFFF systems that have smaller system volumes, require smaller sample volumes and have shorter run times than their macro-scale counterparts. Direct, on-column detection within the miniaturized separation device improved the resolution, decreased the band broadening, lowered the plate height, and shortened the overall analysis time. Also, the information obtained from these detection systems can be used to elucidate information on the electrical and physical characteristics of a sample. Therefore, complimentary on-column detection systems, were designed, fabricated and characterized. Additionally, the data from the two detection systems was compared and a quantitative correlation was performed, enabling the independent use of each detection system.

Thesis (Ph. D.)--University of Kentucky, 2003. / Title from document title page (viewed June 30, 2004). Document formatted into pages; contains xv, 150 p. : ill. Includes abstract and vita. Includes bibliographical references (p. 140-148).

Although molybdenum blue solutions have been known for more than twocenturies, an understanding of their chemical nature is only beginning to emerge.This dissertation aimed at elucidating the structural nature of the polydisperse,nanoscopic components in the solution phases and the solid states of partiallyreduced polyoxomolybdate (Mo-POM). The study offered at least fourcontributions to the area: (1) a rational protocol for the molecular recognition ofMo-POM with de novo organic hosts. (2) demonstration of kinetic precipitation ofa dynamic mixture of polyoxomolybdates and application of the technique to thestudy of the dynamic mixture by TEM (3) characterization of the Mo-POMnanostructures by an unusual combination of complementary analyticaltechniques. (4) a general approach for the synthesis of crown-ethers-containingtripodal molecules.The molecular recognition of Mo-POM with designer tripodal hexaminetris-crown ethers opened a window to the solution phase structures of Mo-POMnanoscopic components. Studies with a series of structurally analogous hostsprobed the relationship between the structure of the molecular host and theformation of nanostructures.An unusual combination of complementary analytical protocols: flow fieldflowfractionation, electron microscopy (transmission and scanning), andinductively coupled plasma – emission spectroscopy, was used to monitor thesolution-phase evolution of Mo-POM nanostructures. The crystallization – drivenformation of keplerate Mo-POM and solution-phase evolution of structurallyrelated nanoscopic species were apparent in the self-assembling process ofpartially reduced Mo-POM.

Thesis (Ph.D.)--Cleveland State University, 2008. / Abstract. Title from PDF t.p. (viewed on May 8, 2008). Includes bibliographical references (p. 121-126). Available online via the OhioLINK ETD Center. Also available in print.

Thesis (doctoral)--Lund University, 1998. / Added t.p. with thesis statement inserted.

Thesis (doctoral)--Lund University, 1998. / Added t.p. with thesis statement inserted.

Thesis (MSc)-- Stellenbosch University, 2012. / ENGLISH ABSTRACT: Over the past two decades, field flow fractionation (FFF), as a polymer characterization technique, has become cutting edge technology. The demand for molar mass and size characterisation of complex polymer systems has increased, especially in cases where classical calibration techniques such as size exclusion chromatography (SEC) has shown several shortcomings. FFF is a technique resembling chromatography. It has several significant advantages over SEC, especially for the characterisation of ultrahigh molar mass (UHMM), branched and gel-containing polymers. In this study, polybutadienes, which often contain the abovementioned species, were analysed by SEC and asymmetric flow field flow fractionation (AF4). Both separation techniques were coupled to refractive index and multi-angle laser light scattering detection. Similarly, polyrotaxanes, which are polymers with complex and unique molecular architectures, were also investigated. Results showed that AF4 can explicitly be used as a superior tool over SEC. In the case of UHMM polybutadienes, much higher molar masses could be detected by AF4, due to the absence of shear degradation which is often encountered in SEC. Gel-containing species could be detected by AF4 as no filtering is required prior to injection. Abnormal retention behaviour, a phenomenon often encountered in UHMM branched polymers, was observed in SEC analysis of the polyrotaxanes materials. AF4 provided sufficient separation from low to high molar masses, without out any irregularities. / AFRIKAANSE OPSOMMING: Gedurende die afgelope twee dekades het veldvloeifraksionering (FFF) as ‘n polimeerkarakteriseringstegniek groot veld gewen. Die aanvraag na molekulêre massa en groottekarakterisering van komplekse polimeersisteme het toegeneem, veral in die gevalle waar klassieke kalibrasietegnieke soos grootte-uitsluitingschromatografie (SEC) etlike tekortkominge getoon het. FFF is ‘n tegniek soortgelyk aan chromatografie, en het voorheen bewys dat dit oor ‘n redelike aantal voordele bo SEC beskik, veral in die geval van ultrahoë molekulêre massa- (UHMM-), vertakte- en jelbevattende spesies. In die huidige studie is polibutadieenpolimere, wat dikwels bogenoemde spesies bevat, geanaliseer met behulp van SEC en onsimmetriese vloei-veldvloeifraksionering (AF4). Beide skeidingstegnieke is gekoppel aan ‘n brekingsindeks en multihoek-laserligverstrooiingsdetektors. Op dieselfde wyse is polirotaksane (polyrotaxanes) met komplekse molekulêre argitektuur bestudeer. Daar is bewys dat AF4 uitsluitlik gebruik kan word as ‘n meer geskikte tegniek bo SEC. Baie hoër molekulêre massas kon deur middel van AF4 vir UHMM polibutadieenpolimere raakgesien word as gevolg van die verminderde afbrekende degradasie wat dikwels voorkom met SEC. Jel-bevattende spesies is suksesvol geïdentifiseer met behulp van AF4 waartydens geen filtrering vir analise nodig was nie. Abnormale retensie was sigbaar tydens SEC analise van monsters van polirotaksane, wat dikwels voorkom in vertakte polimere. In teenstelling het AF4 bewys dat ‘n bevredigende skeiding van klein na groot molekulêre massas, sonder enige tekortkominge, moontlik is.

This work focuses on the integration of microfluidics and dielectrophoresis(DEP) with the principles of field flow fractionation (FFF) to create a continuous-flow isolator for rare and viable circulating tumor cells (CTCs) from peripheral blood mononuclear cells (PBMNs) drawn from cancer patients. The method exploits differences in the plasma membrane capacitances of tumor and blood cells, which correspond to differences in the membrane surface areas of these cell types. DEP-FFF was first adapted to measure cell membrane capacitance, cell density and deformability profiles of cell populations. These properties of the NCI-60 panel of cancer cell types, which represents the wide functional diversity of cancers from 9 organs and leukemia, were compared with the normal cell subpopulations of peripheral blood. In every case, the NCI-60 cells exhibited membrane capacitance characteristics that were distinct from blood and, as a result, they could be isolated from blood by DEP. The heightened cancer cell membrane capacitances correlated strongly with membrane-rich morphological characteristics at their growth sites, including cell flattening, dendritic projections, and surface wrinkling. Following harvest from culture and maintenance in suspension, cancer cells were found to shed cytoplasm and membrane area over time and the suspended cell populations developed considerable morphological diversity. The shedding changed the cancer cell DEP properties but they could still be isolated from blood cells. A similar shedding process in the peripheral blood could account for the surprisingly wide morphological diversity seen among circulating cells isolated from clinical specimens. A continuous flow DEP-FFF method was devised to exploit these findings by allowing CTCs to be isolated from the nucleated cells of 10 mL clinical blood specimens in 40 minutes, an extremely high throughput rate for a microfluidic-based method. Cultured cancer cells could be isolated at 70-80% efficiency using this approach and the isolation of CTCs from clinical specimens was demonstrated. The results showed that the continuous DEP-FFF method delivers unmodified, viable CTCs for analysis, is perhaps universally applicable to isolation of CTCs from different cancer types and is independent of surface antigens - making it suitable for cells lacking the epithelial markers used in currently accepted CTC isolation methods. / text