Thermoacoustic-Piezoelectric Systems with Dynamic Magnifiers

Thermoacoustic energy conversion is an emergent technology with considerable potential for research, development, and innovation. In thermoacoustic resonators, self-excited acoustic oscillations are induced in a working gas by means of a temperature gradient across a porous body and vice versa with no need of moving parts. In the first part of this dissertation, thermoacoustic resonators are integrated with piezoelectric membranes to create a new class of energy harvesters. The incident acoustic waves impinge on a piezo-diaphragm located at one end of the thermoacoustic-piezoelectric (TAP) resonator to generate an electrical power output. The TAP design is enhanced by appending the resonator with an elastic structure aimed at enhancing the strain experienced by the piezo-element to magnify the electric energy produced for the same input acoustic power. An analytical approach to model the thermal, acoustical, mechanical and electrical domains of the developed harvester is introduced and optimized. The performance of the harvesters is compared with experimental data obtained from an in-house built prototype with similar dimensions. In an attempt to further understand the dynamics and transient behavior of the excited waves in the presence of piezoelectric coupling, a novel approach to compute and accurately predict critical temperature gradients that onset the acoustic waves is discussed. The developed model encompasses tools from electric circuit analogy of the lumped acoustical and mechanical components to unify the modeling domain. In the second part of the dissertation, piezo-driven thermoacoustic refrigerators (PDTARs) are presented. The PDTARs rely on the inverse thermoacoustic effect for their operation. A high amplitude pressure wave in a working medium is used to create a temperature gradient across the ends of a porous body located in an acoustic resonator. Finally, PDTARs with dynamic magnifiers are introduced. The developed design is shown, theoretically and experimentally, as capable of potentially enhancing the cooling effect of PDTARs by increasing the temperature gradient created across the porous body

Inflammatory breast cancer: high incidence of detection of mixed human cytomegalovirus genotypes associated with disease pathogenesis

Inflammatory breast cancer (IBC) is highly metastatic, aggressive and fatal form of breast cancer. Patients presenting with IBC are characterized by a high number of axillary lymph node metastases. Recently, we found that IBC carcinoma tissues contain significantly higher levels of human cytomegalovirus (HCMV) DNA compared to other breast cancer tissues, that may regulate cell signaling pathways. In fact, HCMV pathogenesis and clinical outcome can be statistically associated with multiple HCMV genotypes within IBC. Thus, in the present study, we established the incidence and types of HCMV genotypes present in carcinoma tissues of infected non-IBC versus IBC patients. We also assessed the correlation between mixed detection of different HCMV genotypes and disease progression. Genotyping of HCMV in carcinoma tissues revealed that gB1 and gN1 were the most prevalent HCMV genotypes in both non-IBC and IBC patients with no significant difference between patients groups. IBC carcinoma tissues however, showed statistically significant higher incidence of detection of the gN-3b genotype compared to non-IBC patients. The incidence of mixed detection of different gB genotypes showed that gB1+gB3 was statistically significantly higher in IBC than non-IBC patients. Similarly, the incidence of mixed detection of different gN genotypes showed that gN-1+gN-3b and gN3+gN-4b/c were statistically significant higher in the carcinoma tissues of IBC than non- IBC. Mixed presence of HCMV different genotypes was found to be significantly correlated with the number of metastatic lymph nodes in non-IBC but not in IBC patients. In IBC, mixed detection of different HCMV genotypes significantly correlates with lymphovascular invasion and formation of dermal lymphatic emboli, which was not found in non-IBC patients