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University of Minnesota

1. Wu, Kai. Magneto-Nanosensor Platforms for Biosensing Applications.

Degree: PhD, Electrical Engineering, 2017, University of Minnesota

In recent years, magnetic nanoparticles (MNPs) have been widely used in clinical and medical applications. MNPs are used as contrast agents in magnetic particle imaging (MPI) [1-6] and magnetic resonance imaging (MRI)[7, 8], carriers for drug delivery[9-12], tiny heating sources for hyperthermia cancer treatments[13-15], labels for magnetic biosensing[16-23], etc. MNPs-based biosensing strategies have received considerable attention because of their unique advantages over other techniques. For example, iron oxide MNPs are biocompatible, nontoxic, inexpensive to produce, environmentally safe, physically and chemically stable. In addition, most biological samples exhibit diamagnetism or paramagnetism properties, and thus highly sensitive measurements can be performed in visually obscured samples without further processing[24]. This thesis will focus on the use of MNPs for biosensing applications based on two detection platforms: search coil-based biosensor (volumetric based biosensing platform) and giant magnetoresistance (GMR) biosensor (surface based biosensing platform). The volumetric based biosensing platforms measure analytical signals that come from the entire detection volume, which makes assays simple and fast[25]. Representative examples of volumetric sensors include nuclear magnetic resonance (NMR) devices[26, 27], magnetic susceptometers[25, 28], and conventional superconducting-quantuminterference devices (SQUIDs)[29, 30]. In this thesis, the magnetic dynamics of ferrofluids are investigated, the Brownian and Néel relaxation models of MNPs are revisited and optimized, the energy barrier model and dipolar interaction model are taken into consideration in predicting magnetic responses of MNP suspensions. Based on these mathematic models, the hyperthermia performances of MNPs under different alternating magnetic fields (AMF) are evaluated. A search coil-based biosensor system is built up, MNPs have been used for the rapid in vitro human serum viscosity measurement, which successfully measured human serum viscosity in less than 1.5 minutes with an error rate lower than 5%. Furthermore, this search coil system has been used to characterize the physical properties of MNPs in liquid phase. By analyzing the phase lag and harmonic ratios in the MNPs, it is possible to predict the saturation magnetization, the average hydrodynamic size, the dominating relaxation processes of MNPs, and the distinction between single- and multicore nanoparticles. It is feasible to use search coil as a method to characterize physical and magnetic properties of MNPs, which may be applied as building blocks in nanoparticle characterization devices. The surface based biosensing platforms directly detect individual magnetic objects near the sensing elements. These sensors generally achieve higher sensitivity and finer resolution than volumetric ones; however, they require target samples to be placed in close proximity to the sensor surface. Such an arrangement limits the assay configuration, and typically causes the assays to be more…

Subjects/Keywords: Brownian and Néel relaxation; giant magnetoresistance biosensor; immunoassay; Influenza A virus; magnetic nanoparticles; search coil

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Wu, K. (2017). Magneto-Nanosensor Platforms for Biosensing Applications. (Doctoral Dissertation). University of Minnesota. Retrieved from http://hdl.handle.net/11299/198407

Chicago Manual of Style (16th Edition):

Wu, Kai. “Magneto-Nanosensor Platforms for Biosensing Applications.” 2017. Doctoral Dissertation, University of Minnesota. Accessed December 14, 2019. http://hdl.handle.net/11299/198407.

MLA Handbook (7th Edition):

Wu, Kai. “Magneto-Nanosensor Platforms for Biosensing Applications.” 2017. Web. 14 Dec 2019.

Vancouver:

Wu K. Magneto-Nanosensor Platforms for Biosensing Applications. [Internet] [Doctoral dissertation]. University of Minnesota; 2017. [cited 2019 Dec 14]. Available from: http://hdl.handle.net/11299/198407.

Council of Science Editors:

Wu K. Magneto-Nanosensor Platforms for Biosensing Applications. [Doctoral Dissertation]. University of Minnesota; 2017. Available from: http://hdl.handle.net/11299/198407


Universidade do Rio Grande do Sul

2. Geier, Martin. Influência dos parâmetros envolvidos no processo de união por interferência de tubos por cravamento eletromagnético.

Degree: 2014, Universidade do Rio Grande do Sul

A união por conformação eletromagnética de perfis tubulares de alta condutividade elétrica é um processo inovador e limpo que pode substituir com sucesso os processos convencionais de união baseados na fixação mecânica por parafusos, rebites, soldagem e adesivos estruturais. Esta tecnologia funciona a temperatura ambiente, permite a união de materiais diferentes e oferece potencial para promover novas aplicações na montagem de estruturas leves. Neste trabalho busca-se compreender a união por interferência de tubos por cravamento eletromagnético em termos de seus principais parâmetros com o objetivo de identificar a influência na resistência global das uniões e estabelecer a faixa útil de condições operacionais do processo. Inicialmente são apresentados os fundamentos teóricos do processo de conformação eletromagnética e suas principais variantes operacionais, seguido de um resumo do estado atual do conhecimento da aplicação desta tecnologia na união de perfis tubulares no qual é verificado que os parâmetros mecânicos são a tensão residual no mandril, a área e forma da zona de união e o coeficiente de atrito entre os componentes. Entretanto, tais parâmetros estão relacionados de forma complexa com o processo de cravamento eletromagnético, a começar pela energia e a distribuição do pulso de pressão magnética gerados pela máquina e ferramenta que “disparam” o processo de conformação, a folga inicial entre componentes, o material dos componentes e, a geometria, forma e rugosidade do mandril. O estudo experimental foca a união por interferência de tubos de alumínio (AA6082-O) com mandris de aço (AISI 1045) e alumínio (AA6082 nos estados O e T6) investigando de forma gradual a influência de parâmetros do processo na resistência mecânica (à tração) deste tipo de uniões. Os resultados obtidos demonstram que a resistência mecânica da união e os modos de falha associados são diretamente relacionados com os parâmetros de processo e condições do mandril. Além disso, outras importantes contribuições são apresentadas em relação à instrumentação para medição de fluxo magnético e eficiência global do processo e para o desenvolvimento e aplicações industriais desta tecnologia.

Joining of tubular profiles with high electrical conductivity by electromagnetic forming (EMF) is an innovative and clean technology that can successfully replace conventional joining technologies based on mechanical fixing with fasteners, rivets, welding and structural adhesives. The technology works at room temperature, allows joining dissimilar materials and offers potential to foster new applications in the assembly of lightweight tubular frame structures. This work investigates the interference-fit joining of tubes by electromagnetic crimping in terms of its major parameters with the aim of identifying their influence on the overall strength of the joints and establishing the useful range of process operating conditions. Initially, the theoretical principles of EMF and its main operational process variants are presented, followed by a summary of the…

Advisors/Committee Members: Rossi, Rodrigo.

Subjects/Keywords: Electromagnetic forming; Conformação eletromagnética; Processos de fabricação; Tube joining; Interference-fit; Tubos; Magnetic flux measurement; Search coil

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Geier, M. (2014). Influência dos parâmetros envolvidos no processo de união por interferência de tubos por cravamento eletromagnético. (Thesis). Universidade do Rio Grande do Sul. Retrieved from http://hdl.handle.net/10183/96295

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Geier, Martin. “Influência dos parâmetros envolvidos no processo de união por interferência de tubos por cravamento eletromagnético.” 2014. Thesis, Universidade do Rio Grande do Sul. Accessed December 14, 2019. http://hdl.handle.net/10183/96295.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Geier, Martin. “Influência dos parâmetros envolvidos no processo de união por interferência de tubos por cravamento eletromagnético.” 2014. Web. 14 Dec 2019.

Vancouver:

Geier M. Influência dos parâmetros envolvidos no processo de união por interferência de tubos por cravamento eletromagnético. [Internet] [Thesis]. Universidade do Rio Grande do Sul; 2014. [cited 2019 Dec 14]. Available from: http://hdl.handle.net/10183/96295.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Geier M. Influência dos parâmetros envolvidos no processo de união por interferência de tubos por cravamento eletromagnético. [Thesis]. Universidade do Rio Grande do Sul; 2014. Available from: http://hdl.handle.net/10183/96295

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.