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Kim Hyeok,Park Soon-Jung,Park Jae-Hyun,Lee Sunghun,Park Bong Woo,Lee Soon Min,Hwang Ji-Won,Kim Jin-Ju,Kang Byeongmin,Sim Woo-Sup,Kim Hyo-Jin,Jeon Seung Hwan,Kim Dong-Bin,Jang Jinah,Cho Dong-Woo,Moon S 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-
Since an impaired coronary blood supply following myocardial infarction (MI) negatively affects heart function, therapeutic neovascularization is considered one of the major therapeutic strategies for cell-based cardiac repair. Here, to more effectively achieve therapeutic neovascularization in ischemic hearts, we developed a dual stem cell approach for effective vascular regeneration by utilizing two distinct types of stem cells, CD31+-endothelial cells derived from human induced pluripotent stem cells (hiPSC-ECs) and engineered human mesenchymal stem cells that continuously secrete stromal derived factor-1α (SDF-eMSCs), to simultaneously promote natal vasculogenesis and angiogenesis, two core mechanisms of neovascularization. To induce more comprehensive vascular regeneration, we intramyocardially injected hiPSC-ECs to produce de novo vessels, possibly via vasculogenesis, and a 3D cardiac patch encapsulating SDF-eMSCs (SDF-eMSC-PA) to enhance angiogenesis through prolonged secretion of paracrine factors, including SDF-1α, was implanted into the epicardium of ischemic hearts. We verified that hiPSC-ECs directly contribute to de novo vessel formation in ischemic hearts, resulting in enhanced cardiac function. In addition, the concomitant implantation of SDF1α-eMSC-PAs substantially improved the survival, retention, and vasculogenic potential of hiPSC-ECs, ultimately achieving more comprehensive neovascularization in the MI hearts. Of note, the newly formed vessels through the dual stem cell approach were significantly larger and more functional than those formed by hiPSC-ECs alone. In conclusion, these results provide compelling evidence that our strategy for effective vascular regeneration can be an effective means to treat ischemic heart disease.
High Performance Triboelectric Nanogenerator Based on Ultrastretchable Composite Electrode
Jinah Kim,Hyosik Park,Giyong Kim,Ju‑Hyuck Lee,Jinhyoung Park,Sung Yeol Kim 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.6
Recently, stretchable triboelectric nanogenerators have attracted considerable attention as sustainable energy sources for emerging sensors and electronic applications. In this study, we fabricated a high-performance triboelectric nanogenerators (TENG) (SRC-TENG) with excellent stretchability based on a composite electrode composed of a silicone rubber and carbon nanotube (CNT). Our SRC-TENG is capable of 800% elongation and is structurally simple, robust, and easy to fabricate. Moreover, it exhibits excellent performance and delivers a maximum output of 3.52 W/m2 at 100 MΩ, which is comparable to or even higher than those of most ultrastretchable TENGs reported. Furthermore, the output performance of the SRC-TENG is enhanced by optimizing the thickness of the composite in the range of 500–3000 μm. This increase was due to the increase in the interfacial area between the dielectric material and CNTs and the enlargement of the contact area. The fabricated SRC-TENGs show relatively high output performance even in their stretched state (e.g. less than ~ 30% decrease at 200% elongation) and demonstrate excellent long-term stability under a continuous loading of 50,000 cycles. We believe that our design principle for developing a high-performance TENG based on a composite electrode can be further expanded to other combinations of tribomaterials for various applications.
Kim, Jaewook,Shim, In Kyong,Hwang, Dong Gyu,Lee, Yu Na,Kim, Myungji,Kim, Hyeonji,Kim, Seok-Won,Lee, Song,Kim, Song Cheol,Cho, Dong-Woo,Jang, Jinah The Royal Society of Chemistry 2019 Journal of materials chemistry. B, Materials for b Vol.7 No.10
<P>Type 1 diabetes mellitus (T1DM) is a form of diabetes that inhibits or halts insulin production in the pancreas. Although various therapeutic options are applied in clinical settings, not all patients are treatable with such methods due to the instability of the T1DM or the unawareness of hypoglycemia. Islet transplantation using a tissue engineering-based approach may mark a clinical significance, but finding ways to increase the function of islets in 3D constructs is a major challenge. In this study, we suggest pancreatic tissue-derived extracellular matrix as a potential candidate to recapitulate the native microenvironment in transplantable 3D pancreatic tissues. Notably, insulin secretion and the maturation of insulin-producing cells derived from human pluripotent stem cells were highly up-regulated when cultured in pdECM bioink. In addition, co-culture with human umbilical vein-derived endothelial cells decreased the central necrosis of islets under 3D culture conditions. Through the convergence of 3D cell printing technology, we validated the possibility of fabricating 3D constructs of a therapeutically applicable transplant size that can potentially be an allogeneic source of islets, such as patient-induced pluripotent stem cell-derived insulin-producing cells.</P>
탄소 나노 튜브- 실리콘 고무 합성 소재를 이용한 고효율, 신축성 마찰대전 발전 소자
김진아(Jinah Kim),김기용(Giyoung Kim),김성열(Sung yeol Kim),박진형(Jinhyong Park) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4
마찰 대전 발전 소자(TENG)는 서로 다른 두 물질 간 접촉-분리 움직임을 통해 마찰 대전 효과와 정전기 유도 간의 결합 효과를 사용하는 기계적 에너지 발생기이다. (Fan, Tian et al. 2012) 마찰 대전 발전 소자는 다기능 및 휴대용 전자 제품에 에너지를 공급하기위한 대체 전원으로 제안된다. TENG는 기계적 에너지를 사용하기 때문에 기계적 움직임에 쉽게 적용할 수 있는 유연성과 신축성이 필요하다. (Liu, Li et al. 2019) 이 연구에서 CNTs-Dragon Skin 실리콘 고무 나노 복합체를 사용하여 고성능을 나타내며 뛰어난 신축성을 보이는 TENG 를 구현하였다. 마이크로/나노 엔지니어링 된 전극을 TENG에서 사용하여 전극의 표면적에 따른 커패시턴스 증가를 유도하고 이에 따른 TENG의 출력 변화를 분석하였다. 전극 물질과 유전층의 접촉이 TENG 출력에 미치는 영향을 분석하기 위하여 유전 물질의 CNT 양과 분석법에 따른 출력 특성의 변화를 측정하였다. 또한 TENG의 출력에 미치는 전극의 두께 효과를 분석하였다. CNTs-Dragon Skin TENG의 CNTs 농도에 따른 인장특성을 확인하고, 다양한 application에 적용을 위하여 인장 후 접촉-분리 움직임에 따른 출력 변화 및 전극의 저항 변화를 확인하였다. The triboelectric nanogenerator (TENG) is the mechanical energy generator using coupling effect between triboelectric effect and electrostatic induction through the contact-separation motion of two different materials. It is strongly proposed as an alternative power source to supply energy for the multi-functional and portable electronics. Since the TENG uses mechanical energy, it requires flexibility and stretchability that can be easily applied to mechanical movements. In this study, high performance stretchable TENG was demonstrated using CNTs-Dragon Skin silicon rubber nanocomposite. A micro/nanoengineered electrode was used in TENG to induce an increase in capacitance according to the surface area of the electrode, and the change in the output of TENG was investigated. The effect of contact between the electrode material and the dielectric layer on the output of TENG was investigated by confirming the change in output characteristics according to the amount of CNT in the dielectric material and the dispersion method. In addition, we investigated the effect of thickness of electrode on the performance of TENG. The stretchability of CNTs-Dragon Skin TENG according to the CNTs concentration were investigated by measuring of stress-strain curve, in addition change in output and electrode resistance according to the stretching were investigated.
희박 예혼합 연소기에서 연료 조성이 화염전달함수 특성에 미치는 영향
김진아 ( Jinah Kim ),김지환 ( Jihwan Kim ),이정원 ( Jeongwon Lee ),김대식 ( Daesik Kim ) 한국액체미립화학회 2015 한국액체미립화학회지 Vol.20 No.3
Flame transfer function is used to determine the relationship between flow fluctuations and heat release perturbations in a lean premixed gas turbine combustor. The characteristics of flame transfer function are known to depend greatly on flame geometries in addition to other various flow conditions. However, it is not easy to experimentally measure the flame transfer function under various actual combustor operating conditions in terms of time and cost. The current research tries to model the flame transfer function using CFD(Computational Fluid Dynamics). From the results, it is shown that the calculated steady flame geometry can be exactly captured with consideration of the wall heat transfer and radiations. Also, unsteady analysis results show the close characteristics of the flame transfer function to the measured one in both gain and phase.
Chang, Hyeshik,Yeo, Jinah,Kim, Jeong-gyun,Kim, Hyunjoon,Lim, Jaechul,Lee, Mihye,Kim, Hyun Ho,Ohk, Jiyeon,Jeon, Hee-Yeon,Lee, Hyunsook,Jung, Hosung,Kim, Kyu-Won,Kim, V. Narry Elsevier 2018 Molecular cell Vol.70 No.1
<P><B>Summary</B></P> <P>During the maternal-to-zygotic transition (MZT), maternal RNAs are actively degraded and replaced by newly synthesized zygotic transcripts in a highly coordinated manner. However, it remains largely unknown how maternal mRNA decay is triggered in early vertebrate embryos. Here, through genome-wide profiling of RNA abundance and 3′ modification, we show that uridylation is induced at the onset of maternal mRNA clearance. The temporal control of uridylation is conserved in vertebrates. When the homologs of terminal uridylyltransferases TUT4 and TUT7 (TUT4/7) are depleted in zebrafish and <I>Xenopus</I>, maternal mRNA clearance is significantly delayed, leading to developmental defects during gastrulation. Short-tailed mRNAs are selectively uridylated by TUT4/7, with the highly uridylated transcripts degraded faster during the MZT than those with unmodified poly(A) tails. Our study demonstrates that uridylation plays a crucial role in timely mRNA degradation, thereby allowing the progression of early development.</P> <P><B>Highlights</B></P> <P> <UL> <LI> TUT4 and TUT7 are conserved writers of U tail in vertebrates </LI> <LI> mRNA uridylation is induced during early embryogenesis </LI> <LI> Uridylation facilitates the programmed elimination of maternal RNAs </LI> <LI> TUT4 and TUT7 are required for gastrulation in zebrafish and <I>Xenopus</I> </LI> </UL> </P> <P><B>Graphical Abstract</B></P> <P>[DISPLAY OMISSION]</P>