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101.
Abstract Numerical calculations are reported for the transient cooling of a solidified intrusion embedded in a water-saturated porous layer. Heat transfer rates are increased greatly when the intrusion undergoes thermal cracking as it cools. The effects of a uniform heat flux into the porous layer from below are considered. Solutions are obtained for porous layers that are initially above or below the critical-layer Rayleigh number for thermal convection. For conditions considered in this study, the effects on the cooling intrusion of initial convection and layer aspect ratio are small. Results are correlated by scaling velocities with the intrusion Rayleigh number. 相似文献
102.
Hui-Yu Fang Uvarani Chokkalingam Shu-Fen Chiou Tsong-Long Hwang Shu-Li Chen Wei-Lung Wang Jyh-Horng Sheu 《International journal of molecular sciences》2015,16(1):736-746
A new chromene derivative, 2-(4'',8''-dimethylnona-3''E,7''-dienyl)-8-hydroxy-2,6-dimethyl-2H-chromene (1) together with four known natural products, methylfarnesylquinone (2), isololiolide (3), pheophytin a (4), and β-carotene (5) were isolated from the brown alga Homoeostrichus formosana. The structure of 1 was determined by extensive 1D and 2D spectroscopic analyses. Acetylation of 1 yielded the monoacetylated derivative 2-(4'',8''-dimethylnona-3''E,7''-dienyl)-8-acetyl-2,6-dimethyl-2H-chromene (6). Compounds 1–6 exhibited various levels of cytotoxic, antibacterial, and anti-inflammatory activities. Compound 2 was found to display potent in vitro anti-inflammatory activity by inhibiting the generation of superoxide anion (IC50 0.22 ± 0.03 μg/mL) and elastase release (IC50 0.48 ± 0.11 μg/mL) in FMLP/CB-induced human neutrophils. 相似文献
103.
Maxim A. Solovchuk Tony W.H. Sheu Win-Li Lin Ihyuan Kuo Marc Thiriet 《International Journal of Heat and Mass Transfer》2012,55(4):1261-1270
This study investigates the influence of blood vessels on temperature distribution during high-intensity focused ultrasound (HIFU) ablation of liver tumors. A three-dimensional acoustics-thermal-fluid coupling model is simulated to compute the temperature field in the hepatic cancerous region. The model is based on the linear Westervelt and bioheat equations as well as the non-linear Navier–Stokes equations for the liver parenchyma and blood vessels. The effect of acoustic streaming is also taken into account in the present HIFU simulation study. We found from this three-dimensional coupling study that in large blood vessel both the convective cooling and acoustic streaming can significantly change the temperature field and thermal lesion near blood vessels. 相似文献
104.
Wei-Je Huang Ching-Tsung Yu Wen-Jenn Sheu Yen-Cho Chen 《International Journal of Hydrogen Energy》2021,46(31):16522-16533
The effect of non-uniform temperature on the sorption-enhanced steam methane reforming (SE-SMR) in a tubular fixed-bed reactor with a constant wall temperature of 600 °C is investigated numerically by an experimentally verified unsteady two-dimensional model. The reactor uses Ni/Al2O3 as the reforming catalyst and CaO as the sorbent. The reaction of SMR is enhanced by removing the CO2 through the reaction of CaO + CO2 → CaCO3 based on the Le Chatelier's principle. A non-uniform temperature distribution instead of a uniform temperature in the reactor appears due to the rapid endothermic reaction of SMR followed by an exothermic reaction of CO2 sorption. For a small weight hourly space velocity (WHSV) of 0.67 h?1 before the CO2 breakthrough, both a low and a high temperature regions exist simultaneously in the catalyst/sorbent bed, and their sizes are enlarged and the temperature distribution is more non-uniform for a larger tube diameter (D). Both the CH4 conversion and the H2 molar fraction are slightly increased with the increase of D. Based on the parameters adopted in this work, the CH4 conversion, the H2 and CO molar fractions at D = 60 mm are 84.6%, 94.4%, and 0.63%, respectively. After CO2 breakthrough, the reaction of SMR dominates, and the reactor performance is remarkably reduced due to low reactor temperature.For a higher value of WHSV (4.03 h?1) before CO2 breakthrough, both the reaction times for SMR and CO2 sorption become much shorter. The size of low temperature region becomes larger, and the high temperature region inside the catalyst/sorbent bed doesn't exist for D ≥ 30 mm. The maximum temperature difference inside the catalyst/sorbent bed is greater than 67 °C. Both the CH4 conversion and H2 molar fraction are slightly decreased with the increase of D. However, this phenomenon is qualitatively opposite to that for small WHSV of 0.67 h?1. The CH4 conversion and H2 molar fraction at D = 60 mm are 52.6% and 78.7%, respectively, which are much lower than those for WHSV = 0.67 h?1. 相似文献
105.
Sheng-Kai Hsu Kai-Chun Cheng Miracle Oluebube Mgbeahuruike Yi-Hsiung Lin Chang-Yi Wu Hui-Min David Wang Chia-Hung Yen Chien-Chih Chiu Shwu-Jiuan Sheu 《International journal of molecular sciences》2021,22(17)
Under metabolic stress conditions such as hypoxia and glucose deprivation, an increase in the AMP:ATP ratio activates the AMP-activated protein kinase (AMPK) pathway, resulting in the modulation of cellular metabolism. Metformin, which is widely prescribed for type 2 diabetes mellitus (T2DM) patients, regulates blood sugar by inhibiting hepatic gluconeogenesis and promoting insulin sensitivity to facilitate glucose uptake by cells. At the molecular level, the most well-known mechanism of metformin-mediated cytoprotection is AMPK pathway activation, which modulates metabolism and protects cells from degradation or pathogenic changes, such as those related to aging and diabetic retinopathy (DR). Recently, it has been revealed that metformin acts via AMPK- and non-AMPK-mediated pathways to exert effects beyond those related to diabetes treatment that might prevent aging and ameliorate DR. This review focuses on new insights into the anticancer effects of metformin and its potential modulation of several novel types of nonapoptotic cell death, including ferroptosis, pyroptosis, and necroptosis. In addition, the antimetastatic and immunosuppressive effects of metformin and its hypothesized mechanism are also discussed, highlighting promising cancer prevention strategies for the future. 相似文献
106.
107.
The research addresses the issue of determining optimal machine-operator configuration so that the ideal machine-operator ratio can be found and the operator efficiency can be calculated as a part of the overall input efficiency. Formula for optimal machine-operator ratio for single and multiple processor machines are derived. The formula allows us how to determine the best machine-operator ratio and calculate the operator usage efficiency. Simulations are used to verify the formula with matching product releasing times and machine utilisation rate. Data from a wafer reclaim factory is used to illustrate the calculation of equipment usage efficiency. Opportunity for doubling operator usage efficiency is identified using the derived formula. Contributions of this work include: (1) deriving a set of formula to calculate optimal operator-machine configuration and the operator usage efficiency for multi-processor machine sets; (2) identifying the inherent unusable time of operator due to the process time distribution of the machine tools; and (3) doubling the operator usage efficiency of the subject factory. 相似文献
108.
A systematic innovation process (SIP) derived from observations of business practices is proposed and exemplified. Time-wise, the SIP is a series of phases and stages which link the planned business processes from business opportunity identification to technology details to cross-industry application exploitation of newly developed technology/tools/products. Resource-wise, the SIP provides a platform to integrate heterogeneous resources and tools such as TRIZ (Theory of Inventive Problem Solving), non-TRIZ tools, and more opportunity identification and problem solving techniques for systematic innovation. Unlike brain-storming type innovation activities which are often ad-hoc and highly dependent on luck, systematic innovation regards the systematic development of innovative problem solving and/or opportunity identification. The proposed SIP is based on the authors’ observations of industry practices and has not been described elsewhere before. The framework integrates the full phases of systematic innovation processes providing a structured process to enable companies to systematically identify business opportunities and key problems, solve problems, and leverage developed tools/products/technologies for cross-industry exploitations. This SIP also allows for the integration of various tools and knowledge within the overall systematic and cyclic process to support systematic innovation. 相似文献
109.
Chin-You Hsu Chien-Chang Juan Tsing-Shien Sheu Swe-Kai Chen Jien-Wei Yeh 《JOM Journal of the Minerals, Metals and Materials Society》2013,65(12):1840-1847
High-entropy alloys Al x CoCrFeMo0.5Ni with varied Al contents (x = 0, 0.5, 1.0, 1.5, and 2.0) have been designed based on the Al x CoCrCuFeNi system to improve mechanical properties for room and elevated temperatures. They have been investigated for microstructure and mechanical properties. As the aluminum content increases, the as-cast structure evolves from face-centered cubic dendrite + minor σ-phase interdendrite at x = 0 to B2 dendrite with body-centered cubic (bcc) precipitates + bcc interdendrite with B2 precipitates at x = 2.0. This confirms the strong bcc-forming tendency of Al. The room-temperature Vickers hardness starts from the lowest, HV 220, at x = 0, attains to the maximum, HV 720, at x = 1.0, and then decreases to HV 615 at x = 2.0. Compared with the base alloy system, the current alloy system has a superior combination of hardness and fracture toughness. In addition, Al x CoCrFeMo0.5Ni alloys except x = 0 display a higher hot hardness level than those of Ni-based superalloys, including In 718 and In 718 H, up to 1273 K and show great potential in high-temperature applications. 相似文献
110.
Chin-You Hsu Chien-Chang Juan Shin-Tsung Chen Tsing-Shien Sheu Jien-Wei Yeh Swe-Kai Chen 《JOM Journal of the Minerals, Metals and Materials Society》2013,65(12):1829-1839
The high-entropy alloy system Al-Co-Cr-Fe-Mo-Ni has been previously designed based on the Al x CoCrCuFeNi system and was demonstrated to have great improvements in toughness at high hardness level and in softening resistance at elevated temperatures. For this promising system, it is important to have phase diagrams for further efficient alloy design and research. The current study combines the results from scanning electron microscopy, transmission electron microscopy, room-temperature and high-temperature x-ray diffractometry, and differential thermal analysis to construct approximate phase diagrams by varying the content of each composing element. Thermodynamic calculation in considering both mixing enthalpy and entropy was also used to justify the simple phase fields in these phase diagrams. 相似文献