Stability of strip footings above concrete-lined soft ground tunnels

There are cases that footings are underlain by shallow tunnels. The presence of underground tunnels may adversely affect the stability of the overlying footings. Presently, there is no widely accepted analysis or design methodology available to ensure the stability of such footing-soft ground tunnel systems. As a step toward the development of such a methodology, this study was undertaken to investigate the effect of underground tunnel on the bearing capacity of strip footings. In this study, a two-dimensional plane-strain elasto-plastic finite element computer program was used for analysis. Using this computer program, the stability of strip footings was analyzed for a wide range of soil type and tunnel conditions, including tunnel size, tunnel location, and lining thickness. Based on the results of analysis, the mechanistic behavior of the footing-tunnel system was evaluated. Furthermore, bearing capacity equations for strip footings above concrete-lined soft ground tunnels were formulated. The developed equations are shown to be capable of predicting the bearing capacity of footings located above concrete-lined tunnels reasonably well     

Effects of viscosity and surface roughness on gear contact tribological layers

The increasing dependence on more robust additive chemistry to improve gear pitting resistance requires the additive technology development to rely less on a trial‐and‐error approach and more on a better basic understanding of the influence of additive chemistry on tribological contact layers' physical and chemical changes. The use of secondary neutral mass spectrometry (SNMS) and nanoindenter to analyse tribological contact layers had been carried out by Inacker and co‐workers at NMI. They found that the alkyl structure of zinc dithiophosphate (ZDTP) and the type of cation have a profound effect on the thickness and nanohardness of the tribological layer. An extension to that study has been carried out in this investigation, which involves a design experiment of two variables (oil viscosity and surface roughness) while keeping the additive chemistry constant to determine their impact on the tribological layer. The methods used to analyse the tribological layers include SNMS, nanoindenter and SEM coupled with focused ion beam imaging of the rectangular well‐shaped cross section. The results in general are in agreement with the findings of Inacker and his co‐workers, namely greater micropitting reduces the thickness of the tribological layer and brings closer the depth of nanohardness maximum to the surface. Copyright © 2006 John Wiley & Sons, Ltd.     

Soot characterisation and diesel engine wear

The hardness of various types of soot produced by heavy‐ and light‐duty diesel engines of European, Japanese, and North American designs was measured by low‐loss electron energy‐loss spectroscopy (EELS). No clear general trend can be established that shows heavy‐duty diesel engine soot is necessarily harder than light‐duty diesel engine soot. The variation in hardness among individual soot particles produced by the same diesel engine can be as large as differences between the hardest soot particles produced by heavy‐duty diesel engines and the softest soot particles produced by light‐duty diesel engines. There are heavy‐duty diesel engines that can produce soot that is softer than that produced by some light‐duty diesel engines and vice versa. Nevertheless, the hardness of all types of soot studied is close to the range of hardness of metal engine parts. Thus, the results indicate that soot is hard enough to abrade some metal engine parts.     

Red mold dioscorea decreases blood pressure when administered alone or with amlodipine and is a potentially safe functional food in SHR and WKY rats

Hypertension is a risk factor for metabolic syndromes and cardiovascular diseases. Statins are antihypertensive, but can cause rhabdomyolysis as a side effect, which involves the breakdown of muscle fibres and release of myoglobin into the bloodstream. In this study, we used hypertensive rats to investigate whether the interaction between Monascus-fermented products (red mold dioscorea; RMD) and amlodipine increases the risk of rhabdomyolysis and toxicity. A single oral dose of RMD (176 mg/kg) significantly decreased systolic blood pressure (SBP) and diastolic blood pressure (DBP). Moreover, administration of RMD, alone or in combination with amlodipine, did not cause significant rhabdomyolysis and did not impair the metabolic or physiological functions of the liver or kidney. RMD treatment had hypocholesterolemic and hypotriacylglycerolemic effects, indicating that RMD may prevent the incidence of atherosclerosis. The findings of this study lend support to the potential use of RMD as a novel therapeutic and antihypertensive functional food.     

Development of rapid real-time PCR and most-probable-number real-time PCR assays to quantify enterotoxigenic strains of the species in the Bacillus cereus group

Members of the Bacillus cereus group may produce diarrheal enterotoxins and could be potential hazards if they enter the food chain. Therefore, a method capable of detecting all the species in the B. cereus group rather than B. cereus alone is important. We selected nhe as the target and developed a real-time PCR assay to quantify enterotoxigenic strains of the B. cereus group. The real-time PCR assay was evaluated with 60 B. cereus group strains and 28 others. The assay was also used to construct calibration curves for different food matrices and feces. The assay has an excellent quantification capacity, as proved by its linearity (R2 > 0.993), wide dynamic quantification range (10(2) to 10(7) CFU/g for cooked rice and chicken, 10(3) to 10(7) CFU/ml for milk, and 10(4) to 10(7) CFU/g for feces), and adequate relative accuracy (85.5 to 101.1%). For the low-level contaminations, a most-probable-number real-time PCR assay was developed that could detect as low as 10(0) CFU/ml. Both assays were tested with real food samples and shown to beconsiderably appropriate for B. cereus group detection and quantification.     

The improvements of ankaflavin isolated from Monascus-fermented products on dyslipidemia in high-fat diet-induced hasmster

Ankaflavin (AK) is a yellow pigment isolated from Monascus-fermented product. The potential mechanism of AK-regulated dyslipidemia in high-fat diet hamsters was investigated. The results showed that AK treatment reduced plasma total cholesterol (TC) level in hamsters, elevated faecal TC and bile acid concentration, and protected high density apolipoprotein-cholesterol (HDL-C) from diminishing. We further used hepatocytes to demonstrate that AK stabilized HDL levels via nuclear factor-erythroid 2 related factor 2 (Nrf2) activation and downstream molecule haem oxygenase-1 (HO-1) expression, as well as increasing liver x receptor-α (LXRα) mRNA level to promote ATP-binding cassette transporter (ABCA1) and apolipoprotein-A1 (apo-A1) expression. AK increased low density apolipoprotein-cholesterol (LDL-C) expression to promote cholesterol absorption in hepatocytes, and resulted in cholesterol metabolism by cytochrome P450 7A1 (CYP7A1), leading to the conversion of cholesterol into bile acid. Taken together, AK may serve as a cholesterol lowering agent to improve dyslipidemia.     

Degradation on a PTFE/Nafion membrane electrode assembly with accelerating degradation technique

Cost and durability are the main issues of Proton exchange membrane fuel cells (PEMFCs) commercializing. This study uses the accelerate degradation technique to analyze the durability of low cost PTFE/Nafion membrane electrode assembly (MEA). Before the MEA degradation experiment, the MEA must be activated at 65 °C until the performance is stable. Then increase the operation temperature to 80 °C. The experimental process for MEA degradation contains three steps in one cycle. The first step is to open circuit voltage (OCV) for 30 s under R.H. 100%. Then, set 0.6V for 150 s under R.H. 100%. The final step is to set 0.6V for 120 s under R.H. 0%. These three steps take around 5 min to complete. This MEA degradation experiment process includes the OCV, potential cycles, and R.H. cycles. This study uses the polarization curve, AC impedance, cyclic voltammetry (CV), linear sweep voltammetry (LSV), equations and equivalent circuit to analyze state of the MEA. At less than 160 experiment cycles, the result show that catalyst degradation is the main reason for the decay of MEA. After 280 cycles, the MEA begins to exhibit creep deformation due to the R.H. cycle. Electrochemical surface area and high frequency resistance can be used to estimate the degree of MEA degradation approximately.     

Investigation of degradation behavior of membrane electrode assembly with polytetrafluoroethylene/Nafion composite membrane

The main purpose of this study is to investigate the accelerated degradation of the PTFE/Nafion membrane electrode assembly through open circuit voltage and relative humidity cycling. The state of a PTFE/Nafion membrane electrode assembly is evaluated in a fuel cell by monitoring the polarization curve, AC impedance, cyclic voltammetry, and linear sweep voltammetry data over time. The experimental results are then fitted to equations of an equivalent circuit. The results of the first 160 experimental cycles show that catalyst degradation is the main cause for the decay of the membrane electrode assembly. During the 160-520th cycles, the membrane electrode assembly experiences creep deformation, which is due to relative humidity cycling. During the 640-840th cycles, the degradation causes a gradual transition from minor to major membrane cracking; after which the combustion reaction dramatically accelerates membrane electrode assembly degradation.     

Effects of titanium-implanted pre-treatments on the residual stress of TiN coatings on high-speed steel substrates

This investigation examined how titanium ion implantation pre-treatment affects the residual stress of TiN coatings on M2 high-speed steel. Ions were implanted by metal plasma ion implantation. The adhesion strength of the TiN coatings was enhanced by pre-treatment that implanted Ti into the M2 tool steel substrate. The implanted substrate functioned as a buffer layer between the deposited TiN and the tool steel substrate, resulting in variations of the residual stress. The residual stress determined by glancing-angle XRD demonstrates that the deposited TiN films on ion-implanted substrates exhibited reduced compressive stress, from − 3.95 to − 2.41 GPa, which corresponded to a decrease in the grain size of the TiN films. The texture of the TiN film was clearly transformed from the preferred orientation of (220) to (111), subsequently enhancing wear resistance against a tungsten ball.     

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