Swelling and hydraulic characteristics of two grade bentonites under varying conditions for low-level radioactive waste repository design

Chih-Chung Chung,Guo-Liang Ren,I-Ting Chen,Che-Ju, Cuo,Hao-Chun Chang Korean Nuclear Society 2024 Nuclear Engineering and Technology Vol.56 No.4

Bentonite is a recommended material for the multiple barriers in the final disposal of low-level radioactive waste (LLW) to prevent groundwater intrusion and nuclear species migration. However, after drying-wetting cycling during the repository construction stage and ion exchange with the concrete barrier in the long-term repository, the bentonite mechanical behaviors, including swelling capacity and hydraulic conductivity, would be further influenced by the groundwater intrusion, resulting in radioactive leakage. To comprehensively examine the factors on the mechanical characteristics of bentonite, this study presented scenarios involving MX-80 and KV-1 bentonites subjected to drying-wetting cycling and accelerated ion migration. The experiments subsequently measured free swelling, swelling pressure, and hydraulic conductivity of bentonites with intrusions of seawater, high pH, and low pH solutions. The results indicated that the solutions caused a reduction in swelling volume and pressure, and an increase in hydraulic conductivity. Specifically, the swelling capability of bentonite with drying-wetting cycling in the seawater decreased significantly by 60%, while hydraulic conductivity increased by more than three times. Therefore, the study suggested minimizing drying-wetting cycling and preventing seawater intrusion, ensuring a long service life of the multiple barriers in the LLW repository.

Computation of dynamic stiffness and flexibility for arbitrarily shaped two-dimensional membranes

Chen, J.T.,Chung, I.L. Techno-Press 2002 Structural Engineering and Mechanics, An Int'l Jou Vol.13 No.4

In this paper, dynamic stiffness and flexibility for circular membranes are analytically derived using an efficient mixed-part dual boundary element method (BEM). We employ three approaches, the complex-valued BEM, the real-part and imaginary-part BEM, to determine the dynamic stiffness and flexibility. In the analytical formulation, the continuous system for a circular membrane is transformed into a discrete system with a circulant matrix. Based on the properties of the circulant, the analytical solutions for the dynamic stiffness and flexibility are derived. In deriving the stiffness and flexibility, the spurious resonance is cancelled out. Numerical aspects are discussed and emphasized. The problem of numerical instability due to division by zero is avoided by choosing additional constraints from the information of real and imaginary parts in the dual formulation. For the overdetermined system, the least squares method is considered to determine the dynamic stiffness and flexibility. A general purpose program has been developed to test several examples including circular and square cases.

Scaling up the in-hospital hepatitis C virus care cascade in Taiwan

( Chung-feng Huang ),( Pey-fang Wu ),( Ming-lun Yeh ),( Ching-i Huang ),( Po-cheng Liang ),( Cheng-ting Hsu ),( Po-yao Hsu ),( Hung-yin Liu ),( Ying-chou Huang ),( Zu-yau Lin ),( Shinn-cherng Chen ),( 대한간학회 2021 Clinical and Molecular Hepatology(대한간학회지) Vol.27 No.1

Background/Aims: Obstacles exist in facilitating hepatitis C virus (HCV) care cascade. To increase timely and accurate diagnosis, disease awareness and accessibility, in-hospital HCV reflex testing followed by automatic appointments and a late call-back strategy (R.N.A. model) was applied. We aimed to compare the HCV treatment rate of patients treated with this strategy compared to those without. Methods: One hundred and twenty-five anti-HCV seropositive patients who adopted the R.N.A. model in 2020 and another 1,396 controls treated in 2019 were enrolled to compare the gaps in accurate HCV RNA diagnosis to final treatment allocation. Results: The HCV RNA testing rate was significantly higher in patients who received reflex testing than in those without reflex testing (100% vs. 84.8%, P<0.001). When patients were stratified according to the referring outpatient department, a significant improvement in the HCV RNA testing rate was particularly noted in patients from non-hepatology departments (100% vs. 23.3%, P<0.001). The treatment rate in HCV RNA seropositive patients was 83% (83/100) after the adoption of the R.N.A. model, among whom 96.1% and 73.9% of patients were from the hepatology and non-hepatology departments, respectively. Compared to subjects without R.N.A. model application, a significant improvement in the treatment rate was observed for patients from non-hepatology departments (73.9% vs. 27.8%, P=0.001). The application of the R.N.A. model significantly increased the in-hospital HCV treatment uptake from 6.4% to 73.9% for patients from non-hepatology departments (P<0.001). Conclusions: The care cascade increased the treatment uptake and set up a model for enhancing in-hospital HCV elimination. (Clin Mol Hepatol 2021;27:136-143)

Tristetraprolin mediates the anti-proliferative effects of metformin in breast cancer cells

Pandiri, I.,Chen, Y.,Joe, Y.,Kim, H. J.,Park, J.,Chung, H. T.,Park, J. W. Springer Science + Business Media 2016 Breast cancer research and treatment Vol.156 No.1

<P>Metformin, which is a drug commonly prescribed to treat type 2 diabetes, has anti-proliferative effects in cancer cells; however, the molecular mechanisms underlying this effect remain largely unknown. The aim is to investigate the role of tristetraprolin (TTP), an AU-rich element-binding protein, in anti-proliferative effects of metformin in cancer cells. p53 wild-type and p53 mutant breast cancer cells were treated with metformin, and expression of TTP and c-Myc was analyzed by semi-quantitative RT-PCR, Western blots, and promoter activity assay. Breast cancer cells were transfected with siRNA against TTP to inhibit TTP expression or c-Myc and, after metformin treatment, analyzed for cell proliferation by MTS assay. Metformin induces the expression of tristetraprolin (TTP) in breast cancer cells in a p53-independent manner. Importantly, inhibition of TTP abrogated the anti-proliferation effect of metformin. We observed that metformin decreased c-Myc levels, and ectopic expression of c-Myc blocked the effect of metformin on TTP expression and cell proliferation. Our data indicate that metformin induces TTP expression by reducing the expression of c-Myc, suggesting a new model whereby TTP acts as a mediator of metformin's anti-proliferative activity in cancer cells.</P>

Enhancing Network Availability by Tolerance Control in Multi-Sink Wireless Sensor Networks

Chiming Huang,Rei-Heng Cheng,Shau-Ruei Chen,Chung-I Li 한국정보기술융합학회 2010 JoC Vol.1 No.1

A fermentation strategy for production of recombinant protein subjected to plasmid instability

Shu-Jen Chen,Bo-Shun Ke,I-Chung Chiu 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.5

The appearance of plasmid-losing cells in a recombinant Escherichia coli culture was observed when the cell mass became doubled after induction, which corresponded to the timing of cell fission. Accordingly, a two-stage fermentation strategy capable of maintaining plasmid stability without selective pressure in a recombinant E. coli culture was proposed. In the first stage (cell growth stage), a high cell density culture was obtained by incubating the cells in the R medium. In the second stage (producing stage), the cells were devoted to producing the recombinant protein by introducing the fresh LB medium supplemented with isopropyl-β-D-thiogalactopyranoside (IPTG). It was necessary to prevent the doubling in the cell mass after induction; otherwise cell fission would occur and generate plasmid-losing cells. The present strategy is expected to be extensively applicable in recombinant E. coli cultures

Lipopolysaccharide-induced Autophagy Increases SOX2-positive Astrocytes While Decreasing Neuronal Differentiation in the Adult Hippocampus

Liu Wen-Chung,Wu Chih-Wei,Fu Mu-Hui,Tain You-Lin,Liang Chih-Kuang,Chen I-Chun,Hung Chun-Ying,Lee Yu-Chi,Wu Kay L.H. 한국뇌신경과학회 2022 Experimental Neurobiology Vol.31 No.5

Inflammation alters the neural stem cell (NSC) lineage from neuronal to astrogliogenesis. However, the underlying mechanism is elusive. Autophagy contributes to the decline in adult hippocampal neurogenesis under E. coli lipopolysaccharide (LPS) stimulation. SRY-box transcription Factor 2 (SOX2) is critical for NSC self-renewal and proliferation. In this study, we investigated the role of SOX2 in induced autophagy and hippocampal adult neurogenesis under LPS stimulation. LPS (5 ng•100 g-1•hour-1 for 7 days) was intraperitoneally infused into male Sprague–Dawley rats (8 weeks old) to induce mild systemic inflammation. Beclin 1 and autophagy protein 12 (Atg12) were significantly upregulated concurrent with decreased numbers of Ki67- and doublecortin (DCX)-positive cells in the dentate gyrus. Synchronically, the levels of phospho(p)-mTOR, the p-mTOR/mTOR ratio, p-P85s6k, and the p-P85s6k/P85s6k ratio were suppressed. In contrast, SOX2 expression was increased. The fluorescence micrographs indicated that the colocalization of Beclin 1 and SOX2 was increased in the subgranular zone (SGZ) of the dentate gyrus. Moreover, increased S100β-positive astrocytes were colocalized with SOX2 in the SGZ. Intracerebroventricular infusion of 3-methyladenine (an autophagy inhibitor) effectively prevented the increases in Beclin 1, Atg12, and SOX2. The SOX2+-Beclin 1+ and SOX2+-S100β+ cells were reduced. The levels of p-mTOR and p-P85s6k were enhanced. Most importantly, the number of DCX-positive cells was preserved. Altogether, these data suggest that LPS induced autophagy to inactivate the mTOR/P85s6k pathway, resulting in a decline in neural differentiation. SOX2 was upregulated to facilitate the NSC lineage, while the autophagy milieu could switch the SOX2-induced NSC lineage from neurogenesis to astrogliogenesis.

Computation of dynamic stiffness and flexibility for arbitrarily shaped two-dimensional membranes

J. T. Chen,I.L.Chung 국제구조공학회 2002 Structural Engineering and Mechanics, An Int'l Jou Vol.14 No.6

Generation of T Follicular Helper Cells Is Mediated by Interleukin-21 but Independent of T Helper 1, 2, or 17 Cell Lineages

Nurieva, Roza I.,Chung, Yeonseok,Hwang, Daehee,Yang, Xuexian O.,Kang, Hong Soon,Ma, Li,Wang, Yi-hong,Watowich, Stephanie S.,Jetten, Anton M.,Tian, Qiang,Dong, Chen Elsevier 2008 Immunity Vol.29 No.1

<P><B>Summary</B></P><P>After activation, CD4<SUP>+</SUP> helper T (Th) cells differentiate into distinct effector subsets. Although chemokine (C-X-C motif) receptor 5-expressing T follicular helper (Tfh) cells are important in humoral immunity, their developmental regulation is unclear. Here we show that Tfh cells had a distinct gene expression profile and developed in vivo independently of the Th1 or Th2 cell lineages. Tfh cell generation was regulated by ICOS ligand (ICOSL) expressed on B cells and was dependent on interleukin-21 (IL-21), IL-6, and signal transducer and activator of transcription 3 (STAT3). However, unlike Th17 cells, differentiation of Tfh cells did not require transforming growth factor β (TGF-β) or Th17-specific orphan nuclear receptors RORα and RORγ in vivo. Finally, naive T cells activated in vitro in the presence of IL-21 but not TGF-β signaling preferentially acquired Tfh gene expression and promoted germinal-center reactions in vivo. This study thus demonstrates that Tfh is a distinct Th cell lineage.</P>

Cross-Coupled Narrow-Band YBCO Filters with Spurious Suppression by Using a Tap-Connection Technique

L. M. Wang,Chung-I G. Hsu,D. S. Hsieh,L. H. Chen,M. L. Chu,S. M. Chiou 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.48 No.5I

Narrow-band microstrip cross-coupled band-pass filters based on a quadruplet geometry were designed for wireless-communication applications. High-Tc superconducting (HTS) filters were fabricated by patterning YBa2Cu3Oy (YBCO) films double-side deposited on 20-mm-square and 0.5- mm-thick LaAlO3 substrates. The filters with skew-symmetric feed were designed with a center frequency at 1.9 GHz and a bandwidth of 20 MHz. The inductive coupling between the non-adjacent resonators produced a pair of transmission zeros in the frequency response. Also observed was an additional pair of transmission zeros that enhance the out-of-band rejection characteristics. The realized YBCO filter showed a center frequency at 1.925 GHz with a bandwidth of 20 MHz and a minimum insertion loss of about 0.74 dB. Furthermore, a tap-connection technique was applied to cross-coupled HTS band-pass filters so as to suppress the second and/or the third passbands, which were spurious and undesirable. To improve the out-of-band performance of the band-pass filters, we tapped the input/output microstrip lines at certain locations. In this research, we confirmed that by tapping somewhere along the input/output microstrip lines, a /4 open stub or a /2 short stub, where refers to the guided wavelength at 2fo or 3fo, may effectively suppress harmonics at 2fo and/or 3fo by more than 25 dB. The simulated and the experimental results are discussed.