Mesenchymal Stem Cell Secreted-Extracellular Vesicles are Involved in Chondrocyte Production and Reduce Adipogenesis during Stem Cell Differentiation

Tsai Yu-Chen,Cheng Tai-Shan,Liao Hsiu-Jung,Chuang Ming-Hsi,Chen Hui-Ting,Chen Chun-Hung,Zhang Kai-Ling,Chang Chih-Hung,Lin Po-Cheng,Huang Chi-Ying F. 한국조직공학과 재생의학회 2022 조직공학과 재생의학 Vol.19 No.6

BACKGROUND: Extracellular vesicles (EVs) are derived from internal cellular compartments, and have potential as a diagnostic and therapeutic tool in degenerative disease associated with aging. Mesenchymal stem cells (MSCs) have become a promising tool for functional EVs production. This study investigated the efficacy of EVs and its effect on differentiation capacity. METHODS: The characteristics of MSCs were evaluated by flow cytometry and stem cell differentiation analysis, and a production mode of functional EVs was scaled from MSCs. The concentration and size of EVs were quantitated by Nanoparticle Tracking Analysis (NTA). Western blot analysis was used to assess the protein expression of exosomespecific markers. The effects of MSC-derived EVs were assessed by chondrogenic and adipogenic differentiation analyses and histological observation. RESULTS: The range of the particle size of adipose-derived stem cells (ADSCs)- and Wharton’s jelly -MSCs-derived EVs were from 130 to 150 nm as measured by NTA, which showed positive expression of exosomal markers. The chondrogenic induction ability was weakened in the absence of EVs in vitro. Interestingly, after EV administration, type II collagen, a major component in the cartilage extracellular matrix, was upregulated compared to the EV-free condition. Moreover, EVs decreased the lipid accumulation rate during adipogenic induction. CONCLUSION: The results indicated that the production model could facilitate production of effective EVs and further demonstrated the role of MSC-derived EVs in cell differentiation. MSC-derived EVs could be successfully used in cell-free therapy to guide chondrogenic differentiation of ADSC for future clinical applications in cartilage regeneration.

An Improved Frequency and Voltage Restoration Method of the Droop Controls for Power Converters

Meng-jiang Tsai,Po-tai Cheng 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper investigates the conventional droop control and the recently-developed droop control, like virtual synchronous machine (VSM) based control and Q−V control. The VSM based control can effectively smooth frequency dynamics by emulating the damping and the inertia of the synchronous machine, and Q−V droop control can enhance the more ideal results in the reactive power sharing among converters. Both controls bring their frequency and V to the initial values depending on the restoration mechanism. Such a mechanism is achieved by deviating their power reference, and it may lead to severe nonideal power-sharing when the converters asynchronously connect with the system. To improve this problem, this study presents a resetting mechanism realized through a central console. In the end, the laboratory test results are supported to validate their benefits.

Circulating Current Reduction of Parallel Connected Four-Pole Inverters

Meng-Jiang Tsai,Po-Tai Cheng 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

Connecting the four-pole inverters (FPIs) in parallel has many benefits, like lower cost, high flexibility and excellent reliability, and becomes a favorite option in industry. However, such side effects of parallel connection as the circulating current will lead to severe distortion and extra loss. The circulating current is mainly caused by the difference of common mode voltage (CMV) and closely associated with switching states. The zero states contain extremes of CMV levels, which aims to significantly affect the circulating current. This paper presents a three-dimensional pulse width modulation (3-D PWM) approach adapted to the parallel connected FPIs. The 3-D modulation scheme substituting the zero states with active states is socalled three-dimensional active zero state PWM (3-D AZSPWM) and based classical 3-D space vector PWM (3-D SVPWM), possessing low current distortion and high dc-link utilization characteristic. By synthesizing output references without zero states, both CMV levels and circulating current can be suppressed in effect. Based on a two-module parallel connected system, the simplified model is made to discuss the phenomenon of circulating current. Besides, the simulation and test results are presented to validate the performance of 3-D PWM in balanced and unbalanced condition respectively.

Improved DC Voltage Utilization for the Star-Connected Cascaded H-bridges Converter under Unbalanced Voltage Sags

Hsin-Chih Chen,Po-Tai Cheng 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

The static synchronous compensator (STATCOM) are installed at the medium-voltage level of power system for grid voltage regulation and power factor improvement. The star-connected cascaded multilevel converter is widely for high voltage and high rated power STATCOM application. The voltage balancing control is a fundamental issue for cascaded converter, which can be implemented by negative sequence current and zero sequence voltage injection. The zero sequence voltage injection increases the DC voltage utilization, thus the DC voltage and cascaded number should be expanded to avoid over-modulation. However, the increase of DC voltage and cascaded number result in the high cost of the system but reduce the efficiency. On the other hand, the negative sequence current injection results in significant peak current and would trigger the over-current protection. This study provides a voltage balancing strategy to improve the DC voltage utilization by regulating the effectiveness between zero sequence voltage and negative sequence current injection. In addition, the proposed method is based on power flow management. All the unbalanced components of grid voltage and converter output current are considered, thus the proposed method can satisfy for grid fault operation. Laboratory test results are for proposed method variation and validate that the converter can accomplish system operation and manage DC voltage utilization during grid fault operation.

Prognostic Factors in Adult Patients with Solid Cancers and Bone Marrow Metastases

Hung, Yu-Shin,Chou, Wen-Chi,Chen, Tai-Di,Chen, Tse-Ching,Wang, Po-Nan,Chang, Hung,Hsu, Hung-Chih,Shen, Wen-Chi,Cheng, Wei-Hong,Chen, Jen-Shi Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.1

Background: Solid cancers with bone marrow metastases are rare but lethal. This study aimed to identify clinical factors predictive of survival in adult patients with solid cancers and bone marrow metastases. Methods: A total of 83 patients were enrolled consecutively between January 1, 2000 and December 31, 2012. Bone marrow metastases were confirmed by biopsies. Patient clinical features and laboratory data were analyzed for associations. Results: The median age of the patients was 54 years (range, 23-88 years), and 58% were male. The 3 most common primary tumor locations were the stomach (32 patients, 39%), prostate (16 patients, 19%), and lungs (12 patients, 15%). The median overall survival was 49 days (range, 3-1423 days). Patients with Eastern Cooperative Oncology Group performance status 1, cancers of prostate origin, platelet counts over 50,000/ml, and undergoing antitumor therapies had a significantly better prognosis in the multivariate analysis. The median survival times were 173 and 33 days for patients with 2-3 more favorable parameters (n=24) and those with 0-1 (n=69), respectively (hazard ratio 0.30; 95% CI 0.17-0.52, p<0.001). Conclusions: Solid cancers with bone marrow metastases are dismal and incurable diseases. Understanding prognostic factors to these diseases helps medical personnel to provide appropriate treatments and better inform patients about outcomes. Antitumor therapies may improve outcomes in selected patient cohorts.

A Fully Distributed Architecture for the Hybrid Cascaded Converter based Utility Interface

Yu-chen Su,Ping-heng Wu,Po-tai Cheng 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper attempts to develop a utility interface for hybrid renewable energy resources, which is based on the hybrid cascaded converter so that several solar panels and one wind turbine can be integrated together. Different from conventional centralized architecture, this paper decentralizes not only the controller but also the modulator to enhance the modularity and the scalability of the overall system, becoming a fully distributed architecture. Further investigation shows that the power variation between the solar panels and the wind turbine has almost no influence on the power quality. Laboratory test results are provided to verify the feasibility of the discussed system.

UPS Flux Compensation Techniques for Transformer Inrush Reduction

Ming-Yang Yeh,Yu-Hsing Chen,Po-Tai Cheng,Steven Liao,Charles Tsai 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

This paper presents two flux compensation designs for the uninterruptible power supply system. The objective of the flux compensation is to reduce the potential inrush current of the uninterruptible power supply-fed load transformer in the event of grid disturbances and load transformer engagement. The proposed methods utilize the existing voltage and current sensors, and voltage and current control loops of the uninterruptible power supply system for easy implementation. The application scenario is explained, and details of the flux compensation techniques are presented. Laboratory test results are provided for validation.

Control of Cascaded H-Bridges STATCOM based on the Power Flow Management

Ping-Heng Wu,Chia-Tse Lee,Hsin-Chin Chen,Po-Tai Cheng 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

As smart grid techniques are getting more positive perspective and expected to grow in the future, the STATic synchronous COMpensator (STATCOM) has become one of the most important roles to manage the power flow and regulate the grid voltage. The Modular Multilevel Cascaded Converter (MMCC) based on single star bridge cell (SSBC) is very suitable for STATCOM application at the medium-voltage level in the power system. The dc capacitors voltage balancing control is a critical issue to secure the stable operation of MMCCSSBC converter. Four different control methods based on power flow analysis have been considered. The performance of each controller is evaluated under steady state or even Low Voltage Ride Through (LVRT) operation. Each controller has its power flow management and its feature. Experimental test results are given to verify these control methods can well regulated the dc bus voltages under the unbalanced grid voltages.