TOWARD A LOW ENERGY CONSUMPTION SINGLE CELL TESTING SYSTEM

DUONG DUY DUONG 가천대학교 일반대학원 2022 국내박사

The concept of microfluidic devices and its applications are well established and poses leading contributions in industries owing to great prospective in varied applications like biomedical research, clinical diagnostics, immunoassays, and many more. The inclination for miniaturized and simplify instruments for faster, cost-effective fabrication, and deployment is the primary causal objective for this thesis. Before this objective can be apprehended considerable research and development must be performed in several areas where existing microfluidic design suffer limitations, for example expensive materials and overly design lead to low level of reproducibility. When arrested this will allow the use of less expensive and more accessible method to fabricating and test a microfluidic system. The aim of the thesis is to present a few projects where design, fabrication and representation of such microfluidic devices have been performed. The final goal of my work is conceptualization of a single cell analysis system which can be easy to fabricate and operate on a minimal amount of energy. In the first chapter, I summarized the work that has been elaborately discussed in the following chapters. Chapter 2 will talk about a microfluidic device with the function of single cell encapsulation and passively sorting encapsulated cell utilizing inertia. The output encapsulated cells can be used in other applications such as molecular diagnostic to tissue engineering. In the next chapter, I introduce a system of high throughput electrical cell lysis microfluidic device. The device can be used to quickly lyse a large volume cell for the purpose of harvesting the cell’s content. In the final chapter, a microfluidic device that use the energy harvested from small temperature differences to extract cell contents was developed. This is designed with the aim of a quick and easy deployment of the system with no requirement of previous training.

Isolated high boost DC-DC converter based on current-fed topology

Duong, Truong Duy Chonnam National University 2018 국내석사

The renewable energies such as solar cells, fuel cells, photovoltaic have a low voltage and variable, the renewable energies are dependent on the weather conditions, and not stability. To connect them to the industrial application, many high boost DC-DC converters have been presented and investigated to convert low DC voltage into a high DC bus voltage. The isolated topologies can provide the high voltage gain for high step-up ability application. Thus, the isolated boost DC-DC converter based on a new three switches in fuel cell applications is presented in this paper. The major advantages of the proposed current-fed with three switches converter are as follows: continuous input current; decrease one active switch and no use snubber circuit; the primary and secondary voltage waveforms of the high-frequency transformer are not changed; not using snubber capacitor circuit. The operating principles, analysis and parameters selection of the proposed current-fed with three switches converter have been discussed. A prototype of 400 W has been built in the laboratory to verify the performance of the proposed current-fed with three switches converter was used to clarify the DC output voltage at 400 V. The simulation and experimental results are shown to validate the theoretical analysis.

Optical properties of C-rgo and application for two-mode microfiber sensor

Duong Le, Anh Duy 한양대학교 대학원 2020 국내박사

Cytop-reduced graphene oxide (C-rGO) 를 조합하여 이중모드 (two-mode) 마이크로 광섬유 매듭 공진기 (TMM-KR)를 기반으로 일반 환경에서 매우 민감한 상대 습도 (RH) 및 온도 센서를 연구하였습니다. 제안 된 TMM-KR의 RH에 대한 감도는 HE11과 HE12 모드 사이의 유효 굴절 그룹 지수의 차이를 이용하여 완화됩니다. 이 장치는 두 가지 주요 광학 성질로 구성됩니다. Two-mode 마이크로 광섬유 (TMM, 느리게 변하는 항) 및 two-mode 매듭 공진기 (TM-KR, 빠르게 변하는 항) TMM 모드 간섭계로, 마이크로 섬유의 테이퍼링 된 영역은 Two-mode (HE11 및 HE12) 가 여기되고 간섭되어 inline 모드 간섭계를 초래합니다. 기존의 단일 모드 광섬유 (SMF)를 테이퍼링하여 TMM을 제작한 후 C-rGO를 코팅한TMM을 광학 센서로 설계하여 응답 및 복구 시간을 평가했습니다. 마이크로 광섬유의 직경 (~ 4.2㎛)을 최적화함으로써, HE11과 HE12 사이의 유효 굴절률 차이가 억제되어 제안 된 TMM-KR의 RH 감도가 향상됩니다. 고속 푸리에 변환 알고리즘을 사용함으로써, TMM-KR의 광 투과 스펙트럼은 공간 주파수 스펙트럼으로 변환되어 RH의 농도를 정확하게 측정됩니다. 제안 된 TMM-KR 기반 감지 프로브에서 RH의 흡수는 방사형 모드 수 (m) 및 모드 차수 (k)에 따라 TMM 모달 간섭계의 공진 파장과 TMM-KR의 공간 주파수를 효과적으로 변경됩니다. TMM-KR의 기본 모드와 클래딩 모드, HE11 및 HE12 사이의 유효 그룹 굴절률과 제안 된 센서의 감도는 RH 및 온도에 대해 0.603 nm /% 및 -0.79 nm /℃로 현저하게 향상되었습니다. 이론계산 및 실험 결과는 각각 C-rGO-overlaid TMM-KR의 제안 된 미세 구조가 환경 감지의 실제 사용에 적용될 수 있는 광학 특성을 제공 할 것임을 입증했습니다. 마이크로 광섬유 기술의 개발을 지원하는 자기장 센서는 현재의 검출기 및 자기 영향 감시의 다양한 응용 분야에서 저손실, 저비용, 고감도와 같은 더 많은 이점을 포함한 연구 분야의 관심을 끌었습니다. 테이퍼링 구간에서 여기되어 TMM으로 간섭하여HE11과 HE12 모드 사이의 분산 전환점에 접근함으로써 TMM-KR의 두- 파라미터측정의 감도가 향상되었습니다. 제안된 센서는 약한 신호 감지 및 높은 감도의 필수 응용 분야를 연구 할 것으로 예상됩니다. 주변 굴절률 (ARI) 측정을 위해 감도가 높은 TMM-KR을 조사합니다. 그룹 인덱스 차이를 완화 한 후에 제안 된 TMM-KR의 주변 인덱스에 대한 감도가 현저하게 향상 될 것입니다. 이중 파라미터 기반 감지 프로브는 ARI의 표현을 보여 주었으며, 빠른 변동 공진기와 유사하게 실험 감지 비율이 244nm/RIU, 느린 변동 간섭계와 유사하게 1874nm/RIU입니다. 따라서 제안 된 TMM-KR의 다른 주파수 편이를 측정하여 ARI 및 온도 감도를 성공적으로 식별 할 수 있습니다. A highly sensitive relative humidity (RH) and temperature sensor in a living condition based on a two-mode microfiber knot resonator (TMM-KR) combining a cytop-reduced graphene oxide (C-rGO) catalyst is examined. The sensitivity of the proposed TMM-KR to the RH is favorably improved by mitigating the difference in effective refractive group indices between the HE11 and HE12 modes. The device is composed of two main optical features: two-mode microfiber (TMM, slow-varying term) and two-mode knot resonator (TM-KR, fast-varying term). In the TMM modal interferometer, two modes (HE11 and HE12) are excited and interfered in a non-adiabatically up-tapered region of the microfiber, resulting in an inline modal interferometer. After fabricating a TMM by non-adiabatically tapering a conventional single-mode fiber (SMF), I designed C-rGO-overlaid TMM as a polymer-overlaid optical sensor to evaluate the response and recovery times. By optimizing the diameter of the microfiber (∼4.2 m), the difference in effective refractive group indices between HE11 and HE12 is suppressed, resulting in an improved RH sensitivity of the proposed TMM-KR. By using the fast Fourier transform algorithm, optical transmission spectra of the TMM-KR are converted to spatial frequency spectra to precisely measure the concentration of RH. The absorption of RH in the proposed TMM-KR-based sensing probe effectively changes the resonant wavelength of the TMM modal interferometer and the spatial frequencies of the TMM-KR depending on the radial mode number (m) and the mode order (k). The effective group refractive index between fundamental and cladding modes, HE11 and HE12, respectively, of the TMM-KR, and the sensitivities of the proposed sensor remarkably enhanced to 0.603 nm/%, and -0.79 nm/oC, for RH and temperature, respectively. My calculated and experimental results demonstrated that the proposed micro-structure of the C-rGO-overlaid TMM-KR will provide optical properties that can be applied for the practical use of environmental sensing. The magnetic field sensors assisted by the development of microfiber technology have appealed to research interests in versatile applications in present detector and magnetic effect surveillance, including more benefits such as low loss, low cost, high sensitivity. The sensitivity of the two-parameter measurement of the TMM-KR was enhanced by approaching the dispersion turning point between HE11 and HE12 mode, which excited from the non-adiabatically formation in down-tapering transition were interfered producing to the TMM. My proposed sensor is forecasted to study essential applications in weak signal detection and high sensitivity. A TMM-KR with high sensitivity is investigated for ambient refractive index (ARI) measurement. The sensitivity of the proposed TMM-KR to the ambient index will be remarkably enhanced after mitigating the group index difference. The dual-parameter based sensing probe shown a presentation of ARI, with the experimental sensing proportions of 244 nm/RIU analogously to the fast-varying resonator, 1874 nm/RIU analogously to the slow-varying interferometer. Therefore, it is possible to successfully discriminate ARI and temperature sensitivities by measuring different frequency shifts of the proposed TMM-KR.

On Geometric and Algebraic Properties of Human Brain Functional Networks

Duong-Tran, Duy Purdue University ProQuest Dissertations & Theses 2022 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

It was only in the last decade that Magnetic Resonance Imaging (MRI) technologies have achieved high-quality levels that enabled comprehensive assessments of individual human brain structure and functions. One of the most important advancements put forth by Thomas Yeo and colleagues in 2011 [1] was the intrinsic functional connectivity MRI (fcMRI) networks which are highly reproducible and feature consistently across different individual brains. This dissertation aims to unravel different characteristics of human brain fcMRI networks, separately through network morphospace and collectively through stochastic block models.The quantification of human brain functional (re-)configurations across varying cognitive demands remains an unresolved topic. Such functional reconfigurations are rather subtle at the whole-brain level. Hence, we propose a mesoscopic framework focused on functional networks (FNs) or communities to quantify functional (re-)configurations. To do so, we introduce a 2D network morphospace that relies on two novel mesoscopic metrics, Trapping Efficiency (TE) and Exit Entropy (EE). We use this framework to quantify the Network Configural Breadth across different tasks. Network configural breadth is shown to significantly predict behavioral measures, such as episodic memory, verbal episodic memory, fluid intelligence and general intelligence.To properly estimate and assess whole-brain functional connectomes (FCs) is among one of the most challenging tasks in computational neuroscience. Among the steps in constructing large-scale brain networks, thresholding of statistically spurious edge(s) in FCs is the most critical. State-of-the-art thresholding methods are largely ad hoc. Meanwhile, a dominant proportion of the brain connectomics research relies heavily on using a priori set of highly-reproducible human brain functional sub-circuits (functional networks (FNs)) without properly considering whether a given FN is information-theoretically relevant with respect to a given FC. Leveraging recent theoretical developments in Stochastic block model (SBM), we first formally defined and subsequently quantified the level of information-theoretical prominence of a prioriset of FNs across different subjects and fMRI task conditions for any given input FC. The main contribution of this work is to provide an automated thresholding method of individuals' FCs based on prior knowledge of human brain functional sub-circuitry.

PIP5Kγ-dependent PIP2-pool regulates Hippo pathway through Merlin and LATS1

LE DUY THAI DUONG 아주대학교 일반대학원 2024 국내석사

PIP5Kγ-dependent PIP2-pool regulates Hippo pathway through Merlin and LATS1 The Hippo-Salvador signaling pathway is crucial in the regulation of organ size and development. Despite recent findings linking phos-phatidylinositol (4,5)- bisphosphate (PIP2) and its producing enzyme phosphatidylinositol 4-phosphate 5- kinase (PIP5K) to the Hippo pathway, the underlying mechanism is not well understood. In this study, we have demonstrated the role of PIP5Kγ, a member of the PIP5K family, in activating the Hippo pathway in a PIP2-dependent manner. When we introduced PIP5Kγ87 or PIP5Kγ90, which are the two major splice variants of PIP5Kγ, we observed their activation of large tumor suppressor kinase 1 (LATS1) and their inhibition of Yes-associated protein (YAP). Conversely, when we knocked down PIP5Kγ, the opposite effects were observed. Our research also revealed that PIP5Kγ90 interacts with Merlin's band 4.1/ezrin/radixin/moesin (FERM) domain, forming a complex with PIP2 and LATS1 at the PM. Notably, PIP5Kγ90, but not its kinase-deficient mutant, strengthened the interaction between Merlin and LATS1 and recruited LATS1 to the PM. Moreover, the depletion of PIP5Kγ or the use of its inhibitor (UNC3230) increased colony formation in carcinoma cell lines in a YAP- dependent manner. Additionally, we found that PIP5Kγ90 interacts with heat shock cognate 71-kDa protein (Hsc70), which also plays a role in activating the Hippo pathway. In summary, our findings suggest that PIP5Kγ regulates the Hippo-YAP pathway by forming a functional complex with Merlin and LATS1 at the PIP2-rich PM, and it also interacts with Hsc70, contributing to pathway activation. Keywords: Hippo pathway, Merlin, PIP2, PIP5Kγ, Hsc70