All-trans Retinoic Acid-Enhanced Matrix Metalloproteinase 2 Secretion of Human Monocytic THP-1

VU THI HIEN Gachon University 2017 국내석사

Matrix metalloproteinase-2 (MMP-2) also known as gelatinase A, belongs to (MMPs) family and involves in breakdown of extracellular matrix (ECM). Previous studies showed that MMP-2 not only participates in processes of invasion, metastasis and angiogenesis and it also plays an important role in inflammation by cleavage of inflammatory cytokines and chemokines. In this study, we investigated the effects of all-trans retinoic acid (ATRA), an active metabolite of vitamin A, on MMP-2 expression of human monocyte THP-1. Cells treated with various concentrations (from 0.1 nM to 1 μM or 10 μM) or various time points (from 6 h to 72 h) showed a significant increase in MMP-2 mRNA expression. However, cell surface MMP-2 protein was decreased. To evaluate the level of secreted-MMP-2 proteins, culture supernatant was collected, concentrated and subjected to western blot analysis or enzyme-linked immune-sorbent assay (ELISA). Upon ATRA treatment, MMP-2 secretion was induced in both time-and concentration-dependent manners. In Western blot data, MMP-2 secretion from THP-1 cells started to increase after 6 h and reached maximum after 48 h treatment with 100 nM ATRA. Similarly, the data obtained from ELISA indicated the same tendency. Experiments with agonists or antagonists for retinoic acid receptor (RAR) or retinoid X receptor (RXR) revealed that ATRA-induced MMP-2 secretion depends on classical RARα-RXRα heterodimer pathway. There was an increase of intracellular calcium level by ATRA treatment and this increase was inhibited by the treatment with RAR or RXR antagonists or calcium channel blockers Verapamil. Our results revealed that ATRA induced-MMP-2 secretion of human monocytes is mediated through RAR/RXR signaling pathway and dependent on calcium. Additional studies are necessary to fully elucidate the function of secreted MMP-2 induced by ATRA. Keywords: All-trans retinoic acid, Matrix metalloproteinase-2, Secretion, RAR/RXR, THP-1.

Enabling multi-domain service function chaining for network service outsourcing

Vu Anh Vu Soongsil university 2017 국내석사

Recently, Software-defined Networking and Network Function Virtualization has been reforming data centers, giving them the ability to accommodate various new technologies, including Service Function Chaining, which provides quick and flexible network service provision by defining an ordered list of service functions that data packets have to go through. Currently, service providers make service function chains from their services deployed in their data centers. However, in some situations, they need to outsource their services to other third-party providers. This thesis proposes a platform, including its architecture built on top of current Network Function Virtualization model and necessary protocols, to enable distributing Service Function Chaining over multiple managing domains, aiming to establish an environment for Network Service Outsourcing. On top of this platform, we propose a service function path selection algorithm which provides the balance between service chain startup delay and end-to-end latency, adapting to service function chain requirements. Finally, the implementation of the architecture and our algorithm performance evaluation will be shown. 최근에는 소프트웨어 정의 네트워킹 및 네트워크 기능 가상화가 데이터 센터를 개편하여 서비스 기능 체인을 포함한 다양한 신기술을 수용할 수 있게 되었다. 서비스 기능 체인은 데이터 패킷이 순서화 된 서비스 기능 목록을 정의하여 빠르고 유연한 네트워크 서비스를 제공한다. 현재 서비스 제공 업체는 데이터 센터에 구축 된 서비스만으로 서비스 기능 체인을 만든다. 그러나 일부 상황에서는 다른 공급 업체에 서비스를 아웃소싱 해야 한다. 본 논문에서는 네트워크 서비스 아웃소싱 환경 구축을 목표로 다중 관리 영역에 분산된 서비스 기능 체이닝을 가능하도록 하는 프로토콜과 플랫폼을 제안한다. 제안된 플랫폼에서 서비스 기능의 초기구성 지연과 종단간 서비스 지연 사이의 균형을 제공하는 서비스 기능 경로 선택 알고리즘을 구현하고 평가한다.

Accelerating the evolution of bacteriophages targeting Acinetobacter baumannii in host range expansion and determination of its background genetic mechanisms

Vu Thao Nguyen Graduate School, Yonsei University 2024 국내박사

Prior to the discovery and widespread use of antibiotics, bacteriophages (phages) were a potential solution for preventing and treating bacterial infections (1, 2). With the emergence of antimicrobial resistance, there has been a renewed interest in phages (3). However, a major limitation to using phage as therapy is their narrow host range, limiting their effectiveness to specific bacterial strains of the same species (4). To address this limitation, phage training, such as Appelmans protocol, has been proposed as a strategy for expanding the host range of phages (5). Despite its potential, there are currently no reports of the protocol being applied to phages targeting Acinetobacter baumannii, an opportunistic pathogen responsible for a variety of hospitalacquired infections with high mortality rate (6). The aims of my dissertation were to apply the Appelmans protocol for expanding the host range of a phage cocktail targeting A. baumannii and evaluate the therapeutic potential of the expanded host range phages generated from the protocol. Additionally, the genetic mechanism underlying the protocol was also investigated to gain insights into its effectiveness. Chapter I provides a brief overview of Acinetobacter baumannii and highlights the significant global concern surrounding carbapenem-resistant A. baumannii (CRAB) strains. Furthermore, it introduces the fundamental background on bacteriophages and phage therapy, along with their limitations and discusses various approaches to overcome these challenges. Chapter II describes the application of the Appelmans protocol as a host range expansion method to broaden the host range of a phage cocktail targeting CRAB. The assessment of the host range expansion covered both the output cocktail and individual phage clones generated from the method. While the protocol consistently demonstrated the capability to expand the host range of the cocktail, it faced challenges when dealing with CRAB strains. Chapter III delves into the screening and characterization process used to identify potential therapeutic phages. The focus was on evaluating individual phage clones generated from the Appelmans protocol for therapeutic applications. Throughout the evaluation, key factors such as host range stability,lytic growth, transduction potential, and the absence of toxin genes were rigorously examined. However, it is noteworthy that the expanded host range phages obtained from this protocol exhibited limited stability, raising concerns about their suitability for therapeutic purposes. Chapter IV discusses the genetic insights into the Appelmans protocol’s mechanism, not only based on previous studies involving phages targeting different bacterial species but also when applied to the phage cocktail targeting CRAB. A bioinformatics workflow was established to analyze the ancestral of the expanded host range generated from the protocol and the finding revealed that they were recombinant derivatives of prophages induced from encountered bacterial strains. Favorable conditions and explanations for prophage induction during this protocol were proposed to support this genetic mechanism. In conclusion, this dissertation focused on the potential and challenges of a phage training method, especially, the Appelmans protocol in expanding the host range of phages for therapeutic applications. The findings emphasize the importance of understanding the genetic mechanisms underlying phage-host interactions to optimize phage therapy strategies for combating antibioticresistant bacterial infections. Parts of this dissertation are adapted from Vu TN, Clark JR, Jang E, D'Souza R, Nguyen LP, Pinto NA, et al. Appelmans protocol - A directed in vitro evolution enables induction and recombination of prophages with expanded host range. Virus Res. 2023;339:199272.

Preparation of aminoclay-polymer nanocomposite hydrogels

BUI KHAC HOANG VU Gachon University 2017 국내석사

Aminoclay has been revealed to have potential in many applications. In this research, we used freezing-thawing method for 3 consecutive cycles to prepare poly(vinyl alcohol) (PVA) hydrogels composite with magnesium organophyllosilicate (MgAC) and zinc organophyllosilicate (ZnAC-[Cl2]). These hydrogels were tested by gel fraction, swelling ratio and SEM observation. In general, the presence of aminoclay materials reduced the gel fraction but increased the swelling ratio and porous size of hydrogels. The radial diffusion method was applied for antimicrobial test. Staphylococcus aureus and Escherichia coli were chosen as harmful bacteria. The ZnAC-[Cl2]/PVA hydrogels have stronger antimicrobial activity compared to MgAC/PVA hydrogels. We also prepared MgAC/PVA hydrogels with silver nanowire (AgNW) at different concentration. From initial experiments, silver nanowire enhanced antimicrobial activity but did not affect gel fraction and swelling ratio ability

Study of bioflocculation for effective microalgae harvesting

Vu Thai Hai Chau University of Science and Technology 2019 국내박사

The potentials of microalgae to produce various products and simultaneously solve environmental problems has attracted great attention. Nevertheless, microalgae biomass harvesting has remained the bottleneck that needs a sustainable solution. This dissertation studied bioflocculation for that reason. In Chapter 1, the general introduction about microalgae cultivation and especially about the bioflocculation techniques were provided. The extracellular polymeric substances (EPS) were deemed responsible for the bioflocculation. However, with many of microalgae properties were contributed by their associated bacteria, their role in bioflocculation was questioned. To answer this question, Chapter 2 first introduced the techniques to separate the bacteria from the microalgal culture (i.e. establishing axenic microalgal culture) and explained some overlooked issues regarded the use of axenic culture in microalgal biotechnology. Chapter 3 then study the flocculation of a self-flocculating microalga — Ettlia sp. YC001 — with and without the presence of its bacterial community. It revealed that the bacteria has facilitated the flocculation and strengthened the aggregate integrity by altering Ettlia EPS structure. However, it was the high EPS protein to carbohydrate ratio responsible for the high flocculation ability of Ettlia. The produced EPS from some organisms can also be used as bioflocculant to harvest non-flocculating microalgae. The Design of Experiment (DoE) approach was applied to optimize the bioflocculant production from Paenibacillus terrae AM141 bacteria in Chapter 4. The DoE screened four significant cultivation factors out of nine candidates and increased the bioflocculant yield by 2.53 times. The optimum flocculation efficiency of the indigenous Chlorella vulgaris suspension was 86.54 ± 0.56% at the addition of 4.56% v/v AM141 flocculant.

Application of conductive catalysts for enhancing methane generation in a combined anaerobic digestion-microbial electrochemical system

Vu, Mung Thi 경희대학교 대학원 2020 국내석사

The integration of microbial electrochemical system (MES) with anaerobic digestion (AD) is a cutting-edge technology that enables efficient methane production and simultaneously increases wastewater treatment efficiency. When methane is the target by-product, the enhancement of biogas generation compared to conventional AD is paralleled with the rapid degradation of organic matters, VFAs, toxic compounds and the successfully extra electrochemical reduction of carbon dioxide to methane. Performance of methane-producing MES-AD is highly reliant on electron transfer efficiency from electrode to microorganisms and vice versa. In the first part of this study, magnetite nanoparticles were used as electron carriers to enhance extracellular electron transfer in single chamber MESs. The MES with magnetite (MES-M) exhibited the highest methane yield of 0.37 ± 0.009 LCH4/gCOD, which was about 1.42 times higher than that of AD-C (0.26 ± 0.01 LCH4/gCOD). In the similar order, average methane production rate of MES-M (132.7 mL/L.d) was about 49% and 13% higher than that of AD (88.9 mL/L.d) and control MES (117.8 mL/L.d), respectively. The experimental data was observed to be highly consistent with modified Gompertz model results (R2 >0.99), which also showed 74.2% and 22.1% enhanced maximum methane production rate in MES with magnetite as compared to control AD and MES without magnetite. In the second part of this thesis work, magnetite/zeolite (MZ) was successfully synthesized to use as a feasible and cost-effective cathode catalyst for enhancing methane generation in MES-AD system. The novel MZ catalyst consists of hydrophilic zeolite cores and conductive magnetite nanoparticles for enhanced electroactive biofilm development on the cathode by facilitating micro-channels for nutrient diffusion, increased surface area, and reduced charge transfer resistance. The MES using an MZ cathode (MES-MZ) achieved a maximum methane yield of 0.38 ± 0.010 LCH4/gCOD, which was significantly higher than that of the control operation without a catalyst (0.33 ± 0.008 LCH4/gCOD). The average methane production rate was increased about 28.7% from 97.8 mL/(L.d) in the control MES to 125.9 mL/(L.d) in the MES-MZ, along with an improvement in the methane percentage from 73% to 79%. In addition, the maximum current generation was recorded using the MES-MZ at 9.29 ± 0.16 mA, which was about 16% higher than that of 8.0 ± 0.13 mA observed in the control reactor and is consistent with about a 36.2% improvement of the Coulombic efficiency. The CV and EIS analyses revealed that MZ lowered the overpotential losses during the electron transfer process, and revealed a more positive cathode potential with the MES-MZ (-0.48 V vs. Ag/AgCl), which suggests direct electron transfer for the dominant pathway for the conversion of carbon dioxide to methane. In the third part of the thesis work, novel porous reduced-graphene oxide/ hollow titania (rGO/TiO2) was successfully synthesized to be used for promoting electrochemical reduction of CO2 to methane in MES-AD system. The combined porous structure of rGO and hollow TiO2 increased the surface area of cathode. In addition, the superior conductivity of rGO and hydrophilicity of TiO2 promoted the development of electroactive biofilm. The MES-rGO/TiO2 showed highest methane yield and average methane production rate 0.383 ± 0.01 LCH4/gCOD and 152.38 mL/L.d, which is 15.36% and 13.4% higher than that of control MES with bare carbon cloth. The MES-rGO/TiO2 produced the total coulomb of 3837.9 ± 351.5 C, which was about 33% higher than that of the plain cathode with a value of 2887.92 ± 254.6 C. Substrate degradation and the conversion efficiency of VFAs were noted to be improved in the presence of all tested conductive catalysts. Cyclic voltammetry and electrochemical impedance spectroscopy analysis confirmed that conductive catalysts enhanced catalytic activity of biofilm and lowered both solution and charge transfer resistance. The results suggest the application of conductive catalysts as a promising and cost-effective alternative to upgrade methane production in a highly scalable combined MES-AD system in the future.

High efficiency hybrid resonant converter topologies suitable for implementing CC/CV charge of the Electric Vehicle Battery Pack

Vu Hai Nam 숭실대학교 대학원 2017 국내석사

A full-bridge dc-dc converter is widely used in medium and high power applications such as battery charger in electric vehicle and dc-dc converter in energy storage system. Full-bridge dc-dc converter can be classified into two common types. They are full-bridge PWM converter and full-bridge resonant converter. A well-known full-bridge PWM converter is phase shift full-bridge (PSFB) converter which can achieve zero-voltage-switching (ZVS) for all primary switches. Conventional PSFB converter exists some fundamental drawbacks such as hard-switching turn-off of all primary switches, oscillation voltage across rectifier diodes, and reverse recovery current of rectifier diodes. To overcome these drawbacks, chapter 1 proposes a PSFB converter with a resonant active snubber. The proposed converter can achieve nearly ZCS turn-off for all primary switches, clamp oscillation voltage across rectifier diodes and remove reverse recovery current of rectifier diodes. A 3.3 kW prototype converter is implemented to verify the improvement of the proposed PSFB converter. A well-known full-bridge resonant converter is full-bridge LLC resonant converter which can achieve ZVS and naturally eliminate oscillation voltage across rectifier diodes. However, in the case of the battery charger application in which requires CC and CV mode operation, it becomes more challenging due to the wide range of frequency variation. To overcome this problem, chapter 2 proposes a novel dual full-bridge LLC resonant converter. The proposed dual FBLLC resonant converter can implement CC and CV charge for the battery with a narrow range of switching frequency. The dual structure makes the proposed converter possible to achieve ZVS and nearly ZCS for all the primary switches in CC mode operation. Since the proposed converter can operate with a narrow frequency in CV mode, it can minimize the circulating current and achieve nearly ZCS condition. A 6.6 kW prototype converter is implemented to verify the validity of proposed converter and the maximum efficiency of 98.3% was achieved 풀 브리지 DC / DC 컨버터는 전기 자동차 배터리 충전기와 에너지 저장 시스템의 DC / DC 컨버터 등 중용량 및 고용량 전력 응용에 널리 사용되고 있습니다. 풀 브리지 DC / DC 컨버터는 두 개의 일반적인 유형으로 분류 할 수 있는데, 풀 브리지 PWM 컨버터와 풀 브리지 공진형 컨버터입니다. 잘 알려진 풀 브리지 PWM 컨버터는 모든 기본 스위치에 제로 전압 스위칭 (ZVS)을 실현할 수 있는 위상 시프트 풀 브리지 (PSFB) 컨버터입니다. 기존의 PSFB 컨버터는 모든 주요 스위치의 하드 스위칭 턴 오프, 정류 다이오드에서의 발진 전압 및 역회복 전류 등의 단점이 있습니다. 이러한 단점을 극복하기 위해 제 1 장에서는 공진형 액티브 스너버를 갖춘 PSFB 컨버터를 제안하고 있습니다. 제안된 컨버터는 모든 주요 스위치에 거의 영전류 턴 오프를 실현하여 정류 다이오드 사이의 발진 전압 및 클램프 정류 다이오드의 역회복 전류를 제거 할 수 있습니다. 제안 된 PSFB 컨버터의 성능 개선을 검증하기 위해 3.3kW 프로토 타입 컨버터가 구현되었습니다. 또 다른 하나의 풀 브리지 공진 컨버터는 영전압 스위칭을 실현하고 정류 다이오드에서의 발진 전압을 자연스럽게 제거하는 풀 브리지 LLC 공진 컨버터이다. 그러나 CC 모드 및 CV 모드 동작을 필요로 하는 배터리 충전기의 경우, 넓은 범위에서 주파수가 변동하는 문제점이 있습니다. 이러한 문제를 극복하기 위해 2 장에서는 새로운 듀얼 풀 브리지 LLC 공진 컨버터를 제안하고 있습니다. 제안 된 듀얼 풀 브리지 LLC 공진 컨버터는 좁은 범위의 스위칭 주파수에서 배터리 CC 충전 및 CV 충전을 구현할 수 있습니다. 이중 구조로 제안 된 컨버터는 CC 모드 동작에서 모든 주요 스위치에 영전압 스위칭과 영전류 스위칭을 달성 할 수 있게 됩니다. 제안 된 컨버터는 CV 모드 동작에서 좁은 영역의 주파수에서 동작 할 수 있기 때문에 순환 전류를 최소화 시킬 수 있고 영전류 스위칭을 달성 할 수 있습니다. 제안 된 컨버터의 유효성을 검증하기 위해 6.6kW 프로토 타입 컨버터가 구현되어 98.3 %의 최대 효율을 달성했습니다.

A Study on Optics Design for Performance Improvement of Green Energy Systems

Vu, Hoang 일반대학원 정보통신공학과 2023 국내박사

The sun is a major source of inexhaustible free energy (i.e., solar energy) for the planet Earth. Currently, new technologies are being employed to generate electricity from harvested solar energy. These approaches have already been proven and are widely practiced throughout the world as renewable alternatives to conventional non-hydro technologies. Despite this huge potential and increase in awareness, the contribution of solar energy to the global energy supply is still negligible. This issue has several underlying reasons. First, because solar cells have low efficiency, they require space to install, taking up territory that could be used for other purposes. Second, to cut costs and achieve maximum efficiency, high-efficiency solar cells like multi-junction solar cells require concentrated sunlight to operate, necessitating the use of sun-tracking mechanisms. These actuators are unsuitable for applications requiring structural stability such as building and automotive. They thereby restrict how solar energy is used. The third reason is that solar energy is only suited for places with a high solar radiation. Therefore, in this dissertation, optical design methods for optimizing energy obtained from solar energy systems and lighting systems are presented. The designs are based on the theory of non-image optics. The research focuses on the design of concentrator photovoltaic system with solar split spectrum for dual land use applications to improve the Land Equivalent Ratio (LER) and create strategies for the agri-voltaic system optimization, there is research into integrating photovoltaics (PV) and agriculture. We also introduce static concentrator photovoltaic (CPV) systems with stable structure for automotive application, and finally we present an optical design method for illumination that improves distribution uniformity. The results show that the novel technique is an excellent method to design, improve performance, and reduce the cost of the CPV system and lighting system. 태양은 행성 지구를 위한 고갈되지 않는 자유 에너지(즉, 태양 에너지)의 주요 원천입니다. 현재 수확된 태양 에너지로부터 전기를 생성하기 위해 새로운 기술이 사용되고 있습니다. 이러한 접근 방식은 이미 입증되었으며 기존의 비수력 기술에 대한 재생 가능한 대안으로 전 세계적으로 널리 시행되고 있습니다. 이러한 엄청난 잠재력과 인식 제고에도 불구하고 전 세계 에너지 공급에 대한 태양 에너지의 기여도는 여전히 미미합니다. 따라서 본 논문에서는 태양광 에너지 시스템과 조명 시스템에서 얻는 에너지를 최적화하기 위한 광학적 설계 방법을 제시한다. 디자인은 비이미지 광학 이론을 기반으로 합니다. 이 연구는 LER(Land Equivalent Ratio)을 개선하고 농업-발전 시스템 최적화를 위한 전략을 만들기 위해 이중 토지 사용 애플리케이션을 위한 태양 분할 스펙트럼을 갖춘 집광기 태양광 시스템 설계에 중점을 둡니다. 태양광(PV)과 농업을 통합하는 연구가 있습니다. . 또한 안정적인 구조의 자동차용 CPV(Static Concentrator Photovoltaic) 시스템을 소개하고 마지막으로 분포 균일성을 향상시키는 조명용 광학 설계 방법을 제시한다. 결과는 새로운 기술이 CPV 시스템 및 조명 시스템의 설계, 성능 향상 및 비용 절감을 위한 탁월한 방법임을 보여줍니다.

Design and implementation of stateful container service migration over edge clouds

Vu Xuan Tuong 숭실대학교 대학원 2021 국내석사

멀티 액세스 엣지 컴퓨팅(MEC)은 최종 사용자에게 지연시간이 낮은 서비스를 제공하는 새롭고 유망한 기술이다. 그러나 엣지 노드의 제한된 리소스와 사용자의 이동성으로 인해 엣지에 애플리케이션을 배포한다고해서 모바일 사용자에게 지속적인 서비스가 보장되지 않는다. 사용자가 초기 서비스를 제공받는 엣지 노드를 떠나기 때문에 서비스가 종종 중단되고 응답이 지연됩니다. 이전 연구에 따르면 컨테이너 마이그레이션은 이 문제를 처리하는데 많은 이점을 가지고 있다. 그러나 이러한 연구는 컨테이너화 된 워크로드 및 서비스를 배포하고 관리하는 데 사용되는 Kubernetes와 같은 오케스트레이션 프레임워크와 통합되기보다는 Docker와 같은 컨테이너 런타임에만 의존한다. 본 연구에서는 서로 다른 엣지 노드와 엣지 클러스터간에 서비스 연속성 제공하고 워크로드를 빠르게 재 할당하기 위해서 Orchestrated Edge 컴퓨팅 플랫폼에 통합 서비스 마이그레이션 기능을 통합하는 구조 설계 및 구현을 제안한다. Multi-access Edge Computing (MEC) is a new promising technique, which provides low latency services to end-users. However, because of the edge node's limited resources and the mobility of its users, deploying applications at the edge does not guarantee continuous service for mobile users. Since users leave the initial serving edge nodes, services are often interrupted and responses are delayed. Container migration has many advantages in dealing with this issue, according to previous research. However, these studies depend solely on container runtimes like Docker, rather than integrating with orchestration frameworks like Kubernetes, which are used to deploy and manage containerized workloads and services. In this study, we present a design and implementation of an integrating service migration function into the Orchestrated Edge computing platform, which enables transparent service continuity and fast reallocation workloads between different edge nodes and edge clusters.

IEEE 802.15.7 가시광 네트워크에서 CSMA/CA를 위한 우선 순위 기법 : Priority Scheme for CSMA/CA in IEEE 802.15.7 Visible Light Network

Vu Van Huynh Graduate School, Kookmin University 2012 국내석사

Data packets with multi-levels are become one of the most important issues in the indoor environments. To meet the priority MAC protocol for supporting differentiated service applications, we propose a mechanism to support priority MAC based on multi-parameters for IEEE 802.15.7 visible light communication (VLC). Multi-parameters mechanism use four parameters, such as number of backoff times (NB), backoff exponent (BE), contention window (CW), and number of retransmission times (RT) to support the differentiated service applications. We consider beacon-enabled VLC personal area network (VPAN) mode with slotted version for random access algorithm in this thesis. Based on a discrete-time Markov chain, we analyze the performance of proposed mechanism under non-saturation environments. The effect of the proposed mechanism on the throughput, delay and reliability is explored herein. The analytical and simulation results show that our scheme can properly support multi-levels priority in VPAN.