Browsing by Issue Date, starting with "2020-07"

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The impact of Bus Rapid Transit (BRT) on land and property values: A meta-analysis
(2020-07-01)
Zhang, Min
;
Yen, Barbara T. H.
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運輸與物流管理系註：原交通所+運管所
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Department of Transportation and Logistics Management
Throughout the world, Bus Rapid Transit (BRT) has become a popular transit solution for cities wanting to improve urban mobility and economic opportunities through land and property value uplift (LVU). However, the relevant literature reports a mixed impact of BRT on land and property values. This research aims to explain the variation in impacts by conducting a meta-analysis of 23 empirical studies which have estimated the amount of LVU that is attributable to BRT. Using a random-effects model, four categories of factors that may influence estimates of BRT impacts are analysed: BRT system characteristics; land type and accessibility; research methods; and the spatial and temporal characteristics of the case study. Several factors were found to have a statistically significant impact on estimated LVU impacts from BRT systems including maturity of the BRT system; property or land; type of value (asking price, assessed price or sales price); the distance to BRT stations; the research method; and the geographical location of the BRT system. Using the quantifiability advantages of meta-analysis techniques, we further conducted a broad comparison between our results and the findings from one previous meta-analysis study on Rail-Based Transit (RBT), and discussed how the LVU impact differs between BRT and RBT. The findings from this research suggest several key recommendations for future studies into the impact of BRT on land and property values. They also inform policy analyses on transit funding through land and property value gains.
Correlation between breath ammonia and blood urea nitrogen levels in chronic kidney disease and dialysis patients
(2020-07-01)
Chen, Chang-Chiang
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Hsieh, Ju-Chun
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Chao, Cheng-Han
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Yang, Wei-Shun
;
Cheng, Hui-Teng
Previous studies have shown that breath ammonia (breath-NH3) concentration is associated with blood urea nitrogen (BUN) levels. However, interindividual variations in breath-NH3 concentrations were observed. Thus, the present study aimed to assess the effect of oral cavity conditions on breath-NH3 concentration and to validate whether the measurement of breath-NH3 concentration is feasible in clinical settings. A total of 125 individuals, including patients with stage 3 to 5 chronic kidney disease (CKD3-5), those on dialysis, and healthy participants, were recruited. A nanostructured sensor was used to detect breath-NH3 concentrations. Pre- and post-gargling as well as pre- and post-hemodialysis (HD) breath-NH3, salivary pH, and salivary urea levels were measured. Breath-NH3, salivary urea, salivary pH, and BUN levels were positively correlated to each other. Breath-NH3 concentrations were associated with BUN levels (r = 0.43, p < 0.001) and were significantly higher in CKD3-5 (p < 0.005) and dialysis patients (p < 0.001) than in healthy participants. Higher correlation coefficients were noted between breath-NH3 concentrations and BUN levels during follow-up (r = 0.59-0.94, p < 0.05). When the cutoff value of breath-NH3 was set at 523.65 ppb, its sensitivity and specificity in predicting CKD (BUN level >24 mg dl(-1)) were 87.6% and 80.9%, respectively. Breath-NH3 concentrations decreased after HD (p < 0.001) and immediately after gargling (p < 0.01). Breath-NH3 concentration, which was affected by gargling, was correlated to BUN level. The measurement of breath-NH3 concentration using the nanostructured device may be used as a tool for CKD detection and personalized point-of-care for CKD and dialysis patients. The current study had a small sample size. Thus, further studies with a larger cohort must be conducted to validate the effect of oral factors on breath-NH3 concentration and to validate the benefit of breath-NH3 measurement.
On-Chip Over-Voltage Protection Design Against Surge Events on the CC Pin of USB Type-C Interface
(2020-07-01)
Ke, Chao-Yang
;
Ker, Ming-Dou
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
As fast charging being a comprehensive application in universal serial bus (USB) type-C products, the high-power delivery may cause the USB type-C interface in the high risk of surge events. Therefore, a switch realized by high voltage N-type metal oxide semiconductor transistor (HVNMOS) has been added to the configuration channel (CC) pin to prevent the internal circuits from surge damage. However, hot carrier degradation (HCD) on the HVNMOS was induced by surge events, especially when the HVNMOS was operating in the ON-state. To mitigate HCD on the HVNMOS switch during surge events, a new over-voltage protection (OVP) design with selected voltage-level detection was proposed and verified in a 0.15-mu m BCD technology. The proposed OVP circuit with a positive feedback is designed to turn off the gate of the HVNMOS switch for a longer time when surge zapping on the CC pin. The experimental results from silicon chip have successfully verified the proposed OVP structure in device level and circuit level, respectively.
RF/High-Speed I/O ESD Protection: Co-optimizing Strategy Between BEOL Capacitance and HBM Immunity in Advanced CMOS Process
(2020-07-01)
Wu, Wei-Min
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Ker, Ming-Dou
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Chen, Shih-Hung
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Chen, Jie-Ting
;
Linten, Dimitri
In order to meet the requirement of ultrahigh-speed, low latency, and wide bandwidth (BW) in the next 5G mobile network and internet of things (IoT) applications, the parasitic capacitance specification of electrostatic discharge (ESD) protection devices should become much stricter. Reducing the capacitance always degrades the ESD performance in terms of shrinking the size of the ESD protection device. The distributed ESD protection network is one of the solutions which mitigates the capacitance issue and provides a broadband design. However, while the ESD devices are put under the I/O pad in the distributed ESD protection network, back-end-of-line (BEOL) capacitance starts to play an important role in the advanced 28-nm CMOS process. Therefore, a tapered metal structure is proposed to significantly reduce 30% BEOL capacitance of the ESD device, which can gain a 2.8-GHz increase in the operational BW in the distributed network. Meanwhile, it can enhance the human-body-model (HBM) level up to 16% higher than the original layout style under the same front-end-of-line (FEOL) layout size.
Optical microresonator arrays of fluorescence-switchable diarylethenes with unreplicable spectral fingerprints
(2020-07-01)
Okada, Daichi
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Lin, Zhan-Hong
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Huang, Jer-Shing
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Oki, Osamu
;
Morimoto, Masakazu
High-security identification requires authentication that is hard to counterfeit and replicate. For anti-counterfeiting data storage and rewritable memory devices, chromic materials are adoptable, where the dichromatic colours can be switched by external stimuli. If further individual information is embedded in each pixel, a much higher-level security system beyond the zero/one data array will be realized. For this purpose, a fine whispering gallery mode (WGM) fingerprint pattern from a microresonator is applicable. Here we propose that photoswitchable optical microresonators made of a fluorescent photochromic organic material function as anti-counterfeiting, rewritable optical memories. The WGM photoluminescence of the resultant microspheres can be switched on and off repeatedly by irradiation with ultraviolet and visible light. The shape of the micro-resonator varies from a sphere to an oblate ellipsoid and hemisphere, depending on the self-assembly process, and the WGM spectral pattern depends sensitively on the morphology of the resonators. Furthermore, surface self-assembly on a hydrophobic/hydrophilic micropatterned substrate affords a highly integrated array of microresonators as dense as millions of pixels per square centimetre. The spectral fingerprints of all pixels are different from one another; therefore, the photoswitchable microarrays are applicable as an ultimate anti-counterfeiting system which is hard to replicate.
Controlled Sol-Gel and Diversiform Nanostructure Transitions by Photoresponsive Molecular Switching of Tetraphenylethene- and Azobenzene-Functionalized Organogelators
(2020-07-01)
Arumugaperumal, Reguram
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Hua, Wei-Ling
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Raghunath, Putikam
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Lin, Ming-Chang
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Chung, Wen-Sheng
The implementation of stimuli-responsive materials with dynamically controllable features has long been an important objective that challenges chemists in the materials science field. We report here the synthesis and characterization of [2]rotaxanes (R1 and R1-b) with a molecular shuttle and photoresponsive properties. Axles T1 and T1-b were found to be highly efficient and versatile organogelators toward various nonpolar organic solvents, especially p-xylene, with critical gelation concentrations as low as 0.67 and 0.38 w/v %, respectively. The two molecular stations of switchable [2]rotaxanes (R1 and R1-b) can be revealed or concealed by t-butylcalix[4]arene macrocycle, thus inhibiting the gelation processes of the respective axles T1 and T1-b through the control of intermolecular hydrogen-bonding interactions. The sol-gel transition of axles T1 and T1-b could be achieved by the irradiation of UV-visible light, which interconverted between the extended and contracted forms. Interestingly, the morphologies of organogels in p-xylene, including flakes, nanobelts, fibers, and vesicles depending on the molecular structures of axles T1 and T1-b, were induced by UV-visible light irradiation. Further studies revealed that acid-base-controllable and reversible self-assembled nanostructures of these axle molecules were mainly constructed by the interplay of multi-noncovalent interactions, such as intermolecular pi-pi stacking, CH-pi, and intermolecular hydrogen-bonding interactions. Surprisingly, our TPE molecular systems (R1, R1-b, T1, and T1-b) are nonemissive in their aggregated states, suggesting that not only fluorescence resonance energy transfer but also aggregation-caused quenching may have been functioning. Finally, the mechanical strength of these organogels in various solvents was monitored by rheological experiments.
發生負面社會責任事件是否傳遞盈餘資訊性？
(國立交通大學經營管理研究所, 2020-07-01)
陳慶隆
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王翰屏
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林信煒
;
邱秀婕
;
Ching-Lung Chen
本研究以Collins et al.（1994）的盈餘資訊性模型為實證架構，探討公司發生資訊公告類型負面聲譽事件是否傳遞盈餘資訊性。公司發生資訊公告類型負面聲譽事件，在某種程度意味管理者較不重視公司聲譽，對會計報導或盈餘品質的要求較低。而我國上市（櫃）公司內部控制有效性評估，除少數情境外，並非強制揭露的報告，故投資者對公司內部控制制度的良窳或執行內部控制的態度，欠缺正式報告加以評估。倘若資訊公告類型負面聲譽事件可以傳遞公司是否重視聲譽或存在內部控制缺失的訊息，則發生此類型負面聲譽事件公司可能有較低之盈餘品質，本研究預期低盈餘品質將降低盈餘與報酬間的連結，降低盈餘資訊性。在排除發生非資訊公告類型負面聲譽事件樣本後，實證結果顯示：相較於未發生負面聲譽事件之公司，發生資訊公告類型負面聲譽事件之公司，有顯著較低之未來盈餘資訊性；在部分設定下，該公司亦有顯著較低之當期盈餘資訊性。此實證發現意味投資者將發生資訊公告類型的負面聲譽事件，解讀為影響公司風險管理與未來盈餘持續性之因子，並將之納入評價決策，導致該公司有較低之盈餘資訊性。本研究進行若干敏感性測試，發現實證結果具備相當的穩固性。
Reactive Sputtering Deposition of Epitaxial TiC Film on Si (100) Substrate
(2020-07-01)
Fang, Yu-Siang
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Thi Hien Do
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Chiu, Kun-An
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Chen, Wei-Chun
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Chang, Li
Epitaxial (100) TiC film deposition on Si (100) substrate by direct current magnetron reactive sputtering of a metallic Ti target with 3%-6% CH4 in Ar gas was investigated. X-ray diffraction and cross-sectional scanning transmission electron microscopy (STEM) reveal that epitaxial cubic TiC can be grown on the Si substrate by domain matching epitaxy in 5/4 ratio with the epitaxial relationship of TiC (100)[0 (1) over bar1] // Si (100)[0 (1) over bar 1]. For sputtering with 3% and 4% CH4, the deposited films are found to consist of both TiC and metallic Ti phases. Increasing the CH4 flow ratio to 5% results in a deposited film completely consisting of TiC without metallic Ti phase. The crystallinity of the deposited TiC is also improved with increasing the CH4 ratio to 5%. X-ray photoelectron spectroscopy shows that the [C]/[Ti] atomic ratio in TiC is nearly close to 1 for growth with 5% CH4 flow ratio and above. The measured electrical resistivities of the deposited films also increase from 41 to 153 mu omega center dot cm with increasing the CH4 ratio from 3% to 6%. With film growth beyond 50 nm thickness, it is shown that some disoriented TiC grains are formed.
Privacy in Data Service Composition
(2020-07-01)
Barhamgi, Mahmoud
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Perera, Charith
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Yu, Chia-Mu
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Benslimane, Djamal
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Camacho, David
In modern information systems different information features, about the same individual, are often collected and managed by autonomous data collection services that may have different privacy policies. Answering many end-users' legitimate queries requires the integration of data from multiple such services. However, data integration is often hindered by the lack of a trusted entity, often called a mediator, with which the services can share their data and delegate the enforcement of their privacy policies. In this article, we propose a flexible privacy-preserving data integration approach for answering data integration queries without the need for a trusted mediator. In our approach, services are allowed to enforce their privacy policies locally. The mediator is considered to be untrusted, and only has access to encrypted information to allow it to link data subjects across the different services. Services, by virtue of a new privacy requirement, dubbed k-Protection, limiting privacy leaks, cannot infer information about the data held by each other. End-users, in turn, have access to privacy-sanitized data only. We evaluated our approach using an example and a real dataset from the healthcare application domain. The results are promising from both the privacy preservation and the performance perspectives.
Retrieval of Uniaxial Permittivity and Permeability for the Study of Near-Field Radiative Transport Between Metallic Nanowire Arrays
(2020-07-01)
Chang, Jui-Yung
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Sabbaghi, Payam
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Weng, Yu-Shao
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Chen, Yu-Bin
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Wang, Liping
Recently metamaterials made of periodic nanowire arrays, multilayers, and grating structures have been studied for near-field thermal radiation with enhanced coupling of evanescent waves due to surface plasmon/phonon polariton, hyperbolic mode, epsilon-near-zero and epsilon-near-pole (ENP) modes, guided mode, and wave interference. In this work, both effective uniaxial electric permittivity and magnetic permeability of a nanowire-based metamaterial are retrieved theoretically through the far-field radiative properties obtained by finite difference time-domain (FDTD) simulations. The artificial magnetic response of metamaterials, which cannot be obtained by traditional effective medium theory (EMT) based on electric permittivity of constitutes only, is successfully captured by the nonunity magnetic permeability, whose resonant frequency is verified by an inductor-capacitor model. By incorporating the retrieved electric permittivity and magnetic permeability into fluctuational electrodynamics with multilayer uniaxial wave optics, the near-field radiative heat transfer between the metallic nanowire arrays is theoretically studied and spectral near-field heat enhancements are found for both transverse electric and magnetic waves due to artificial magnetic resonances. The understanding and insights obtained here will facilitate the application of metamaterials in near-field radiative transfer.
Assessment on rack intake flowrate uniformity of data center with cold aisle containment configuration
(2020-07-01)
Chu, Wen-Xiao
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Wang, Rui
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Hsu, Po-Hao
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Wang, Chi-Chuan
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機械工程學系
The present paper investigates the rack intake flowrate uniformity in a simulated container data center subject to cold aisle containment (CAC) configuration. Based on a novel flowrate uniformity index (FUI) in prior study, a strong flowrate mal-distribution at the rack inlets is observed by examining the standard deviation of FUI (sigma(FUI)). When raising the supplied volumetric flowrate from 2.52 m(3) s(-1) to 3.40 m(3) s(-1), the outlet temperature of each cabinet is remarkably reduced. Meanwhile, applying a gradient fan speed for cabinets can reduce the sFUI by 19.5-34.0%. However, the mal-distribution for the top and bottom cabinets is still prominent. In essence, adding air supply flowrate or changing rack intake layout show limited improvements and may even have potentially deleterious effects. To tailor the mal-distribution problem, a novel configuration featuring the concept of Coanda effect is proposed. A triangular deflector is implemented to guide the cold air sweeping through fan trays in front of the data rack. The sFUI can be effectively reduced by about 51.3-62.0% compared to the original design, showing a significant improvement on the intake flowrate distribution for all racks.
Antibacterial polypeptide/heparin composite hydrogels carrying growth factor for wound healing
(2020-07-01)
Hsu, Fang-Ming
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Hu, Ming-Hsien
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Jiang, Yi-Sheng
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Lin, Bi-Yun
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Hu, Jin-Jia
We report an efficient growth factor delivering system based on polypeptide/heparin composite hydrogels for wound healing application. Linear and star-shaped poly(L-lysine) (l-PLL and s-PLL) were chosen due to not only their cationic characteristics, facilitating the efficient complexation of negatively charged heparin, but also the ease to tune the physical and mechanical properties of as-prepared hydrogels simply by varying polypeptide topology and chain length. The results showed that polymer topology can be an additional parameter to tune hydrogel properties. Our experimental data showed that these composite hydrogels exhibited low hemolytic activity and good cell compatibility as well as excellent antibacterial activity, making them ideal as wound dressing materials. Unlike other heparin-based hydrogels, these composite hydrogels with heparin densely deposited on the surface can increase the stabilization and concentration of growth factor, which can facilitate the healing process as confirmed by our in vivo animal model. We believe that these PLL/heparin composite hydrogels are promising wound dressing materials and may have potential applications in other biomedical fields.
Development and Characterization of a Fucoidan-Based Drug Delivery System by Using Hydrophilic Anticancer Polysaccharides to Simultaneously Deliver Hydrophobic Anticancer Drugs
(2020-07-01)
Lai, Yen-Ho
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Chiang, Chih-Sheng
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Hsu, Chin-Hao
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Cheng, Hung-Wei
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Chen, San-Yuan
Fucoidan, a natural sulfated polysaccharide, which can activate the immune response and lessen adverse effects, is expected to be an adjuvant agent in combination with chemotherapy. Using natural hydrophilic anticancer polysaccharides to simultaneously encapsulate hydrophobic anticancer drugs is feasible, and a reduced side effect can be achieved to amplify the therapeutic efficacy. In this study, a novel type of fucoidan-PLGA nanocarrier (FPN-DTX) was developed for the encapsulation of the hydrophobic anticancer drug, docetaxel (DTX), as a drug delivery system. From the comparison between FPN-DTX and the PLGA particles without fucoidan (PLGA-DTX), FPNs-DTX with fucoidan were highly stable with smaller sizes and dispersed well without aggregations in an aqueous environment. The drug loading and release can be further modified by modulating relative ratios of Fucoidan (Fu) to PLGA. The (FPN 3-DTX) nanoparticles with a 10:3 ratio of Fu:PLGA displayed uniform particle size with higher encapsulation efficiency than PLGA NPs and sustained drug release ability. The biocompatible fucoidan-PLGA nanoparticles displayed low cytotoxicity without drug loading after incubation with MDA-MB-231 triple-negative breast cancer cells. Despite lower cellular uptake than that of PLGA-DTX due to a higher degree of negative zeta potential and hydrophilicity, FPN 3-DTX effectively exerted better anticancer ability, so FPN 3-DTX can serve as a competent drug delivery system.
Rapid and room temperature synthesis of MAPb(1-x)Sn(x)Br(3-2x)Cl(2x) perovskite quantum dots with enhanced lifetime in warm WLEDs: A step towards environmental friendly perovskite light harvester
(2020-07-01)
Singh, Rajan Kumar
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Som, Sudipta
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Dutta, Somrita
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Jain, Neha
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Singh, Jai
In this work, a facile approach to develop nontoxic CH3NH3PbBr3 perovskite quantum dots (PQDs) by substituting tin (Sn2+) ion instead of lead (Pb2+) ion and chloride (Cl-) ion instead of bromide (Br-) ion has been reported. Synchronized cation and anion substitution in CH3NH3Pb1-xSnxBr3-2xCl2x PQDs has resulted in commercial-friendly properties like fine-tuning of bandgap, shifting of color emission from green to cyan region (523 nm-490 nm), enhancing structural stability, excitonic lifetime, and color gamut. Presence of Sn2+ cations in +2 state, Cl- anions in -1 state, and ion exchange was confirmed from various spectroscopic and morphological analyses. Photoluminescence quantum yield (PLQY) for unsubstituted CH3NH3PbBr3 was observed as 97.50% and it is reduced to > 50% for 15% SnCl2 substituted CH3NH3PbBr3 PQDs because of the presence of defect-related nonradioactive recombination centres while cation and anion changeover. Warm white LED prototype with 123% color gamut encircling as per National Television System Committee Standard was achieved using as prepared CH3NH3Pb1-xSnxBr3-2xCl2x PQDs and commercial red phosphor on the blue LED chip. The inflated colour-gamut, promising PLQY, and slender FWHM of as-synthesized CH3NH3Pb1-xSnxBr3-2xCl2x PQDs illustrate great prospect to explore their utilization in display applications. Reduction in toxicity in perovskite material was confirmed by the biological study.
A simple analytical solution for organic contaminant diffusion through a geomembrane to unsaturated soil liner: Considering the sorption effect and Robin-type boundary
(2020-07-01)
Lin, Ye-Chen
;
Yeh, Hund-Der
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環境工程研究所
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Institute of Environmental Engineering
Landfill leachate often contains soluble hazardous substances. Geomembrane (GM) liner is commonly used to protect the subsurface water. The leachate however may diffuse through the GM and enter the underlying natural soil liner. Analytical or numerical modeling for the leachate transport in the soils helps assess the associated risk to groundwater resources. The analytical model has the advantages of simplicity and easy to implement over the numerical model. Yet there is only an analytical model developed for describing the leachate migration through the GM to the unsaturated soil liner. Its solution however is difficult to evaluate. We herein develop a new analytical model to include the sorption effect and simplify the leachate transport through the GM as a Robin-type boundary condition in the model. The solution of the model is in a simple form and very easy to evaluate. The present solution is then compared with a finite-difference solution and the existing solution. The effect of the retardation factor on the leachate migration is investigated. A sensitivity analysis is also performed to assess the effects of model parameters on the leachate distribution. Finally, the present solution is adopted to estimate the transport parameters based on the data from bench-scale composite liner experiments. Landfill leachate often contains soluble hazardous substances. Geomembrane (GM) liner is commonly used to protect the subsurface water. The leachate however may diffuse through the GM and enter the underlying natural soil liner. Analytical or numerical modeling for the leachate transport in the soils helps assess the associated risk to groundwater resources. The analytical model has the advantages of simplicity and easy to implement over the numerical model. Yet there is only an analytical model developed for describing the leachate migration through the GM to the unsaturated soil liner. Its solution however is difficult to evaluate. We herein develop a new analytical model to include the sorption effect and simplify the leachate transport through the GM as a Robin-type boundary condition in the model. The solution of the model is in a simple form and very easy to evaluate. The present solution is then compared with a finite-difference solution and the existing solution. The effect of the retardation factor on the leachate migration is investigated. A sensitivity analysis is also performed to assess the effects of model parameters on the leachate distribution. Finally, the present solution is adopted to estimate the transport parameters based on the data from bench-scale composite liner experiments.
Advances in Quantum-Dot-Based Displays
(2020-07-01)
Huang, Yu-Ming
;
Singh, Konthoujam James
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Liu, An-Chen
;
Lin, Chien-Chung
;
Chen, Zhong
In terms of their use in displays, quantum dots (QDs) exhibit several advantages, including high illumination efficiency and color rendering, low-cost, and capacity for mass production. Furthermore, they are environmentally friendly. Excellent luminescence and charge transport properties of QDs led to their application in QD-based light-emitting diodes (LEDs), which have attracted considerable attention in display and solid-state lighting applications. In this review, we discuss the applications of QDs which are used on color conversion filter that exhibit high efficiency in white LEDs, full-color micro-LED devices, and liquid-type structure devices, among others. Furthermore, we discuss different QD printing processes and coating methods to achieve the full-color micro-LED. With the rise in popularity of wearable and see-through red, green, and blue (RGB) full-color displays, the flexible substrate is considered as a good potential candidate. The anisotropic conductive film method provides a small controllable linewidth of electrically conductive particles. Finally, we discuss the advanced application for flexible full-color and highly efficient QD micro-LEDs. The general conclusion of this study also involves the demand for a more straightforward QD deposition technique, whose breakthrough is expected.
一例一休下智慧型護理排班系統之研製
(國立交通大學經營管理研究所, 2020-07-01)
黃允成
;
侯宜璇
;
Yun-Cheng Huang
;
Yi-Xuan Hou
護理排班在護理管理中是一項非常重要的工作，整體護理排班品質的良窳，會直接間接影響護理人力之應用。本研究考量護理人員對班表之滿意度，且須滿足勞基法、一例一休、連續值班、人員偏好、排班與休假之公平性、…等等因素，應用數學規劃法建構數學模型，使用Micorsoft Excel 2010、Micorsoft Visual Basic 2010與Lingo11.0程式語言，將數學規劃模型開發成整合式電腦排班系統，經由電腦快速運算，求解出初步最佳化班表，作為護理排班之參據。
The study of corrosion behavior of manganese-based conversion coating on LZ91 magnesium alloy: Effect of addition of pyrophosphate and cerium
(2020-07-01)
Jian, Shun-Yi
;
Tzeng, Yu-Chih
;
Ger, Ming-Der
;
Chang, Ko-Lun
;
Shi, Gia-Nan
A previous study by the authors reported that a Mn-Ce based conversion coating protects the surface of LZ91 magnesium alloy from corrosion. However, the acidic permanganate solution decomposes after several days of storage and this significantly affects the properties of the coating. To address this problem, this study presents a method to stabilize the acidic permanganate bath by adding pyrophosphate into the bath. The results show that all conversion coatings are amorphous and comprise two layers: a porous layer that contacts the substrate and a compact overlay. Coatings that are produced using a bath with Ce are more resistant to corrosion than those that are produced in a bath without Ce ions. Coatings that are stored in the Mn-Ce bath for 2 weeks are significantly less resistant to corrosion than coatings that are produced using an as-prepared Mn\\Ce bath. The salt spray test results of coatings that are produced using the as-prepared bath and stored for 2 weeks are found similar because the bath is rendered more stable by the addition of pyrophosphate. (C) 2020 The Authors. Published by Elsevier Ltd.
Clusters of Circulating let-7 Family Tumor Suppressors Are Associated with Clinical Characteristics of Chronic Hepatitis C
(2020-07-01)
Tsai, Yi-Shan
;
Yeh, Ming-Lun
;
Tsai, Pei-Chien
;
Huang, Ching-, I
;
Huang, Chung-Feng
Hepatitis C virus (HCV) infections can cause permanent liver-related diseases, including hepatocellular carcinoma (HCC). Low mortality and incidence of HCC have been observed in patients with chronic hepatitis C undergoing direct-acting antiviral therapy. Tumor suppressive let-7 family members are down-regulated in HCC. The present study, therefore, aimed to investigate whether expression levels for the full spectrum of let-7 family members (let-7a, 7b, 7c, 7d, 7e, 7f, 7g, 7i, and miR-98) in the circulatory system are useful as surveillance biomarkers for liver-related diseases to monitor treatment efficacy during HCV infection. To this end, we measured the levels of mature circulating let-7 family members using quantitative reverse transcription-PCR in 236 patients with HCV infection, and 147 age- and sex-matched controls. Using hierarchical cluster analysis and principal component analysis, three clusters were obtained after measuring expression levels of let-7 family members in the patients and controls. Cluster 1 included let-7a/d/e/g, Cluster 2 comprised let-7b and let-7i, and Cluster 3 comprised let-7c/f/miR-98. Let-7b/c/g represented the three clusters and showed the best survival response to liver cancer when analyzed with respect to patient data. Therefore, considering the circulating levels of let7 b/c/g as representatives of the let-7 family may facilitate effective monitoring of liver-related disease.
Tubular transcriptional co-activator with PDZ-binding motif protects against ischemic acute kidney injury
(2020-07-01)
Wu, Chia-Lin
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Chang, Chia-Chu
;
Yang, Tao-Hsiang
;
Tsai, Alexander Charng-Dar
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Wang, Jui-Lin
Transcriptional co-activator with PDZ-binding motif (TAZ) is a key downstream effector of the Hippo tumor-suppressor pathway. The functions of TAZ in the kidney, especially in tubular epithelial cells, are not well-known. To elucidate the adaptive expression, protective effects on kidney injury, and signaling pathways of TAZ in response to acute kidney injury (AKI), we used in vitro (hypoxia-treated human renal proximal tubular epithelial cells [RPTECs]) and in vivo (mouse ischemia-reperfusion injury [IRI]) models of ischemic AKI. After ischemic AKI, TAZ was up-regulated in RPTECs and the renal cortex or tubules. Up-regulation of TAZ in RPTECs subjected to hypoxia was controlled by I kappa B kinase (IKK)/nuclear factor kappa-light-chain-enhancer of activated B cell (NF-kappa B) signaling. TAZ overexpression attenuated hypoxic and oxidative injury, inhibited apoptosis and activation of p38 and c-Jun N-terminal kinase (JNK) proteins, and promoted wound healing in an RPTEC monolayer. However, TAZ knockdown aggravated hypoxic injury, apoptosis, and activation of p38 and JNK signaling, delayed wound closure of an RPTEC monolayer, and promoted G(0)/G(1) phase cell-cycle arrest. Chloroquine and verteporfin treatment produced similar results to TAZ overexpression and knockdown in RPTECs, respectively. Compared with vehicle-treated mice, chloroquine treatment increased TAZ in the renal cortex and tubules, improved renal function, and attenuated tubular injury and tubular apoptosis after renal IRI, whereas TAZ siRNA and verteporfin decreased TAZ in the renal cortex and tubules, deteriorated renal failure and tubular injury, and aggravated tubular apoptosis. Our findings indicate the renoprotective role of tubular TAZ in ischemic AKI. Drugs augmenting (e.g., chloroquine) or suppressing (e.g., verteporfin) TAZ in the kidney might be beneficial or deleterious to patients with AKI.