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Cholesteryl alpha-D-glucoside 6-acyltransferase enhances the adhesion of Helicobacter pylori to gastric epithelium
(2020-03-13)
Jan, Hau-Ming
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Chen, Yi-Chi
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Yang, Tsai-Chen
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Ong, Lih-Lih
;
Chang, Chia-Chen
Helicobacter pylori, the most common etiologic agent of gastric diseases including gastric cancer, is auxotrophic for cholesterol and has to hijack it from gastric epithelia. Upon uptake, the bacteria convert cholesterol to cholesteryl 6 '-O-acyl-alpha-D-glucopyranoside (CAG) to promote lipid raft clustering in the host cell membranes. However, how CAG appears in the host to exert the pathogenesis still remains ambiguous. Herein we identified hp0499 to be the gene of cholesteryl alpha-D-glucopyranoside acyltransferase (CGAT). Together with cholesteryl glucosyltransferase (catalyzing the prior step), CGAT is secreted via outer membrane vesicles to the host cells for direct synthesis of CAG. This significantly enhances lipid rafts clustering, gathers adhesion molecules (including Lewis antigens and integrins alpha 5, beta 1), and promotes more bacterial adhesion. Furthermore, the clinically used drug amiodarone was shown as a potent inhibitor of CGAT to effectively reduce the bacterial adhesion, indicating that CGAT is a potential target of therapeutic intervention. Jan et al. identify cholesteryl alpha-D- glucopyranoside acyltransferase as a key enzyme in Helicobacter pylori's synthesis of cholesteryl 6'-O-acyl-alpha-D-glucopyranoside, which promotes bacterial adhesion. This study provides insights into the H. pylori-induced pathogenesis and therapeutic strategies against it.
Investigation of non-unique relationship between soil electrical conductivity and water content due to drying-wetting rate using TDR
(2019-03-26)
Chung, Chih-Chung
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Lin, Chih-Ping
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Yang, Shi-Hui
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Lin, Jhe-Yi
;
Lin, Chun-Hung
The characterization of the relationship between volumetric soil water content (theta) and bulk electrical conductivity (EC) (or electrical resistivity) is of high interest in fields of engineering, fundamental petrophysical, hydrological model parameterization, and quantitative hydrogeophysical interpretations. Based on the relationship, for instance, the broad-area image using electrical resistivity tomography (ERT) can be transformed into theta tomograms as initial/boundary conditions of the slope stability analysis. However, the relationship is affected by the hysteresis, leading the inconsistency in drying-wetting circles. Therefore, this study focused on the factor of soil drying-wetting rate using the proposed time domain reflectometry (TDR) method and related sensors for such characterization. A modified pressure plate apparatus enhanced by TDR was first employed with a relatively low rate in which EC and theta were measured simultaneously, without evident non-unique relationship. A TDR penetrometer was then designed for acquiring the temporal variations of theta and EC in the field. On the basis of certain assumptions, observations showed an apparent dependency of the slope of the theta-EC rating curve on rates, but no hysteresis pattern. Finally, a laboratory controlled fast wetting drying cell was used to increase the response time, proving that both the hysteresis and slopes of the theta-EC rating curves were obviously affected by the soil drying-wetting rate, as a significant finding to the related topics.
Metabolic labelling of cholesteryl glucosides in Helicobacter pylori reveals how the uptake of human lipids enhances bacterial virulence
(2016-01-01)
Jan, Hau-Ming
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Chen, Yi-Chi
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Shih, Yu-Yin
;
Huang, Yu-Chen
;
Tu, Zhijay
Helicobacter pylori infects approximately half of the human population and is the main cause of various gastric diseases. This pathogen is auxotrophic for cholesterol, which it converts upon uptake to various cholesteryl alpha-glucoside derivatives, including cholesteryl 6'-acyl and 6'-phosphatidyl alpha-glucosides (CAGs and CPGs). Owing to a lack of sensitive analytical methods, it is not known if CAGs and CPGs play distinct physiological roles or how the acyl chain component affects function. Herein we established a metabolite-labelling method for characterising these derivatives qualitatively and quantitatively with a femtomolar detection limit. The development generated an MS/MS database of CGds, allowing for profiling of all the cholesterol-derived metabolites. The subsequent analysis led to the unprecedented information that these bacteria acquire phospholipids from the membrane of epithelial cells for CAG biosynthesis. The resulting increase in longer or/and unsaturated CAG acyl chains helps to promote lipid raft formation and thus delivery of the virulence factor CagA into the host cell, supporting the idea that the host/pathogen interplay enhances bacterial virulence. These findings demonstrate an important connection between the chain length of CAGs and the bacterial pathogenicity.
Game-Based Remedial Instruction in Mastery Learning for Upper-Primary School Students
(2013-04-01)
Lin, Chun-Hung
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Liu, Eric Zhi-Feng
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Chen, Yu-Liang
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Liou, Pey-Yan
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Chang, Maiga
The study examines the effectiveness of using computer games for after-school remedial mastery learning. We incorporated instructional materials related to "area of a circle" into the popular Monopoly game to enhance the performance of sixth-grade students learning mathematics. The program requires that students enter the answers to avoid the shortcomings of multiple-choice questions. Throughout the game, whenever students are unable to answer questions correctly they receive immediate remedial instruction specifically for that question. This study sought to compare the effectiveness of game-based and video-based remedial instruction incorporated with elements of mastery learning. The results demonstrate that (a) both instructional videos and the proposed Monopoly game enhance the learning of mathematical concepts; and (b) the Monopoly game is more effective than instructional videos at leveraging the benefits of mastery learning. The goal of the research was to integrate games and mastery learning into after-school remedial instruction and design a game to practice the steps of mastery learning.
Diverse Synthesis of Natural Trehalosamines and Synthetic 1,1 '-Disaccharide Aminoglycosides
(2019-01-18)
Lu, Yen-Chu
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Mondal, Soumik
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Wang, Ching-Chi
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Lin, Chun-Hung
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Mong, Kwok-Kong Tony
A general strategy for the diverse synthesis of ten disaccharide aminoglycosides, including natural 2-trehalosamine (1), 3-trehalosamine (2), 4-trehalosamine (3), and neotrehalosyl 3,3 '-diamine (8) and synthetic aminoglycosides 4-7, 9, and 10, has been developed. The aminoglycoside compounds feature different anomeric configurations and numbers of amino groups. The key step for the synthesis was the glycosylation coupling of a stereodirecting donor with a configuration-stable TMS glycoside acceptor. Either the donor or acceptor could be substituted with an azido group. The aminoglycosides prepared in the present study were characterized by 1D and 2D NMR spectroscopy.
Multiple Reflection Analysis of TDR Signal for Complex Dielectric Spectroscopy
(2018-11-01)
Lin, Chih-Ping
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Ngui, Yin Jeh
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Lin, Chun-Hung
;
交大名義發表
;
National Chiao Tung University
Most dielectric spectroscopy techniques require careful system calibration, tedious measurement, specially designed probes, precise input source, and some even involved complicated inversion models. This paper proposed a rapid, robust, and model-free multiple reflection analysis (MRA) of time-domain reflectometry (TDR) signals to measure the complex dielectric permittivity (CDP) spectrum. The key to MRA approach is to decompose the first top reflection and the subsequent multiple reflections from TDR signal and to compare their spectral ratio (MRA ratio). This ratio was theoretically derived from the transmission line theory and found to be independent of source function and impedance mismatches in the leading sections. Based on this theoretical formulation, the CDP spectrum can be uniquely inverted from the measured MRA ratio through optimization and an iterated initial guess method. Numerical evaluations and experimental verifications had proven that MRA is a reliable algorithm for measuring CDP spectrum covering 10 MHz-I CHz. Factors influencing the reliable frequency region were discussed and recommendations on enhancing CDP measurement was proposed for highly dispersive materials. The MRA approach enables dielectric spectroscopy to be conveniently conducted in both laboratory and field, without complicated system setup and calibration.
Quantitative Interpretation of Surface Wave Testing for Assessment of Ground Improvement by Jet Grouting
(2017-01-01)
Lin, Chih-Ping
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Lin, Chun-Hung
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Chang, Yu-Cheng
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Chien, Chih-Jung
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防災與水環境研究中心
Jet grouting technique is special in that the ground becomes highly heterogeneous after installing the improvement columns. The surface wave method was recently shown to hold good promise to assess the average property of the improved ground and evaluate the area replacement ratio. Even though the improved ground was highly heterogeneous along the seismic survey line, the surface wave method worked well and yielded a homogenized shear wave velocity profile. The increase of shear wave velocity after ground improvement was found to be correlated with the area replacement ratio. This study further examined the quantitative relation between the percentage increase of shear wave velocity and the area replacement ratio. The effect of offline sampling (perpendicular to survey direction) was also investigated. 3D spectral element method was utilized for the numerical investigation. Numerical results show that the offline sampling range is about 75%-85% of the wavelength. Hence, it should be noted when planning survey lines. Furthermore, a positive correlation between replacement ratio and velocity increase exist and the difference caused by the velocity contrast between soils and improved columns could be neglected as the velocity contrast becomes greater than about 5. An empirical predictive model between the velocity increase percentage and area replacement ratio was established based on the numerical simulations.
Geotechnical applications and standardization of surface wave method-from engineer's perspective
(2010-01-01)
Lin, Chih-Ping
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Lin, Chun-Hung
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Chang, Tzong-Sheng
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土木工程學系
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Department of Civil Engineering
This paper focuses on the power and concerns of surface wave method in geotechnical applications. It is increasingly used to map not only the vertical variation but also the lateral variation of S-wave velocity. The methods available for surface wave testing and analysis are reviewed and re-examined. Case histories are presented to highlight unique features of surface wave method and point out potential problems. The solution to those problems is proposed and further standardization of surface wave testing is suggested.
Dispersion analysis of surface wave testing - SASW vs. MASW
(2017-08-01)
Lin, Chih-Ping
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Lin, Chun-Hung
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Chien, Chih-Jung
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交大名義發表
;
National Chiao Tung University
The data reduction method for dispersion relation in surface wave testing is conventionally associated with the certain method of data acquisition, for example, phase shift analysis in the two-station SASW method and 2-D multi-station wavefield transformation of surface wave in the MASW method. The fundamental difference in dispersion analysis between the 2-station and multi-station approach was clarified in this study. Limited to the two channel data, conventional dispersion analysis of SASW suffers from possible phase un-wrapping errors, inefficient data filtering and synthesis, and inability to distinguish multiple modes. The MASW approach, on the other hand, can avoid these problems and provide visualization of dispersion relation through 2D wavefield transformation. As opposed to multiple shots in the SASW testing, the MASW testing typically uses only single shot, limiting the obtainable wavelengths due to near field and far field effects. Combining the merits of these two methods, a multi-shot common receiver configuration survey is proposed to acquire multi-station wavefield for 2D wavefield transformation using as few as two receivers. An additional benefit of the multi-shot common receiver configuration is shown to be better control and higher lateral resolution of the measurement range. (C) 2017 Elsevier B.V. All rights reserved.
Application of surface wave method in assessment of ground modification with improvement columns
(2017-07-01)
Lin, Chun-Hung
;
Lin, Chih-Ping
;
Dai, Yung-Zheng
;
Chien, Chih-Jung
;
交大名義發表
Surface wave testing is considered a promising method for assessing average property and actual area replacement ratio of ground modification with improvement columns, owing to its non-destructive nature and large sampling range. However, the surface wave method is essentially a 1-D method assuming horizontally-layered medium. What it measures in highly heterogeneous improved ground remains to be investigated. This study aimed at evaluating the feasibility of surface wave method in the heterogeneous ground with improved columns, and investigating the homogenization of shear wave velocity and the lateral sampling range. Field tests on a jet grouted construction site showed that the surface wave method worked well in such heterogeneous grounds and yielded a site-representative shear wave velocity profile regardless of the survey location. This is attributed to the survey condition where the wavelength is greater than the spacing of grout columns. 1-D analytical models and 2-D numerical simulations were conducted to investigate the quantitative relation between construction parameters and the percentage increase of shear wave velocity after ground improvement. A quantitative approach to estimate the area replacement ratio and overall quality of improvement columns by surface wave testing is proposed. (C) 2017 Elsevier B.V. All rights reserved.

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