Chung Yuan Christian University

About: Chung Yuan Christian University is a education organization based out in Taoyuan City, Taiwan. It is known for research contribution in the topics: Membrane & Fuzzy logic. The organization has 9819 authors who have published 11623 publications receiving 213139 citations. The organization is also known as: Tiong-gôan-tāi-ha̍k & CYCU.

Caffeine Induces Cell Death via Activation of Apoptotic Signal and Inactivation of Survival Signal in Human Osteoblasts

Abstract: Caffeine consumption is a risk factor for osteoporosis, but the precise regulatory mechanisms are currently unknown. Here, we show that cell viability decreases in osteoblasts treated with caffeine in a dose-dependent manner. This cell death is attributed primarily to apoptosis and to a smaller extent, necrosis. Moreover, caffeine directly stimulates intracellular oxidative stress. Our data support caffeine-induced apoptosis in osteoblasts via a mitochondria-dependent pathway. The apoptotic biochemical changes were effectively prevented upon pretreatment with ROS scavengers, indicating that ROS plays a critical role as an upstream controller in the caffeine-induced apoptotic cascade. Additionally, p21-activated protein kinase 2 (PAK2) and c-Jun N-terminal kinase (JNK) were activated in caffeine-treated osteoblasts. Experiments further found that PAK2 activity is required for caffeine-induced JNK activation and apoptosis. Importantly, our data also show that caffeine triggers cell death via inactivation of the survival signal, including the ERK- and Akt-mediated anti-apoptotic pathways. Finally, exposure of rats to dietary water containing 10~20 μM caffeine led to bone mineral density loss. These results demonstrate for the first time that caffeine triggers apoptosis in osteoblasts via activation of mitochondria-dependent cell death signaling and inactivation of the survival signal, and causes bone mineral density loss in vivo.

Anticorrosively enhanced PMMA–SiO2 hybrid coatings prepared from the sol–gel approach with MSMA as the coupling agent

Abstract: A series of sol–gel derived organic–inorganic hybrid coatings consisting of organic poly(methyl methacrylate) (PMMA) and inorganic silica (SiO2) were successfully synthesized by using 3-(Trimethoxysilyl)propyl methacrylate as a coupling agent. In this work, MSMA is first copolymerized with methyl methacrylate monomer at specific feeding ratio by using benzoyl peroxide (BPO) as initiator. Subsequently, the as-prepared copolymer (i.e., sol–gel precursor) is then cohydrolyzed with various contents of tetraethyl orthosilicate (TEOS) to afford chemical bondings to the forming silica networks, giving a series of hybrid sol–gel coatings. Transparent organic–inorganic hybrid sol–gel coatings with different contents of silica are always achieved. The as-synthesized hybrid sol–gel materials were subsequently characterized by Fourier-Transformation infrared (FTIR) spectroscopy and transmission electron microscopy (TEM). The hybrid sol–gel coatings with low silica loading (e.g., 5 wt.%) on cold-rolled steel (CRS) coupons were found much superior in anticorrosion efficiency over those of neat PMMA based on a series of electrochemical measurements of corrosion potential, polarization resistance, corrosion current, and corrosion rate in 5 wt.% aqueous NaCl electrolyte. The enhancement of corrosion protection effect of hybrid sol–gel coatings may be due to the increase of adhesion strength of hybrid sol–gel coatings on CRS coupons relative to neat PMMA, which was further evidenced by the Scotch tape test evaluation. The increase of adhesion strength of hybrid sol–gel coatings on CRS coupons may be attributed to the formation of Fe–O–Si covalent bonds at the interface of coating/CRS system based on the FTIR–RAS (reflection absorption spectroscopy) studies. Effects of the material composition on the thermal stability, mechanical strength, wettability, and surface morphology of neat copolymer and a series of hybrid sol–gel materials, in the form of coating/film, were also studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), hardness tests, contact angle measurement, and atomic force microscopy (AFM), respectively.

ISFET performance enhancement by using the improved circuit techniques

Abstract: An approach to enhance accuracy of the output signal obtained from ISFET interface electronics due to the body effect is proposed. Based on an MOS drawing the same drain current as the ISFET, the scheme allows reduction of influence of body effect. The presented readout interface improves the accuracy of pH measurements, while maintaining operation at constant drain-source voltage and current condition. Using only one ISFET with a differential output configuration, we obtained temperature-dependency and long-term drift as well as common noise compensation. The proposed technique is simple and has a universal use for different ISFETs. In addition, a voltage-controlled dc offset error compensation circuit modulates the extracted signal to the desired dc level for the A/D converter for each sensor. Simulation and experimental results show a great effect on monolithic ISFET integration in CMOS technology.