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The DC-bus voltage control is critical for stable operation of the three-phase four-wire Active Power Filter. DC-bus stable voltage loop and balance voltage loop are established based on the small signal model. Considering the disadvantages of the traditional PI control, second-order low-pass filter is introduced into the proposed controller. Simulation and experimental results are conducted to validate the effectiveness of the proposed strategy.

Objective The aim of our study was to investigate the effects of (−)-epigallocatechin-3-gallate (EGCG, the major phytochemistry component in green tea) on the expression of connexin43 (Cx43) gene and detect the intercellular communication of the human bladder cancer cell lines BIU-87, and explore its possible mechanisms of prevention and cure for the bladder tumor.

Thirty years ago, Unger and Orci proposed the bihormonal-abnormality hypothesis, which highlighted that both deficient insulin secretion and excessive glucagon levels contributed to the hyperglycemic state in type 2 diabetes. The plasma free fatty acid (FFAs) concentrations are higher in patients with diabetes and prediabetes, suggesting that FFAs may be involved in the pathophysiology of diabetes. In type 2 diabetes, at least in the obese form, insulin does not seem to correct the exaggerated alpha cell responses. This phenomenon suggests that the inability of insulin to suppress the glucagon level could be caused by alpha cell insulin resistance. However, it has remained unclear whether alpha cell insulin resistance is caused by FFAs. Recent studies have demonstrated that long-term exposure to elevated FFA levels leads to hypersecretion of glucagon and accumulation of triglycerides (TG) in clonal alpha-TC1-6 cells, but the mechanism of FFA-induced alpha cell insulin resistance is unclear. We hypothesize that long-term exposure to FFAs reduces AMP-activated protein kinase (AMPK) activity and increases TG accumulation in alpha cells, leading to impaired insulin signaling of alpha cells and hypersecretion of glucagon. This hypothesis provides the first detailed examination of the effects of FFAs on alpha cells with glucagon hypersecretion. It potentially suggests that improving alpha cell insulin resistance as well as reversing lipotoxicity will normalize alpha cell function and may benefit glucose control. Consequently, AMPK and insulin-related pathways in alpha cells could be potential targets for controlling glucagon secretion and glucose counter-regulation.

Heat-resistant alloys, Haynes 230 and SS310, were exposed to air and humidified H2 at 750 °C for up to 1000 h, respectively, simulating the environments in reduced temperature solid oxide fuel cells (SOFCs). The oxidized samples were characterized by using SEM, EDS and X-ray diffraction to obtain the morphology, thickness, composition and crystal structure of the oxide scales. A mechanism for the formation of metallic Ni-rich nodules on top of the oxide scale in Haynes 230 sample oxidized in humidified H2 was established. Thermodynamic analysis confirmed that MnCr2O4 is the favored spinel phase, together with Cr2O3, in the oxide scales.

The influence of mold pressing parameters on the positive temperature coefficient of high-density polyethylenel carbon black composites was investigated. The composites with a low resistivity at room temperature and a high positive temperature coefficient can be obtainee with the mold pressing parameters as follows: mold pressing pressure 6–14MPa, mold pressing temperature 150–170°C, mold pressing time about 15 min, and room temperature of molded specimen after cooding for 20–60 minutes. The positive temperature coefficient effect of the composite is 7.7 when it is prepared under the mold pressing parameters, and the negative temperature coefficient effect is less than 0.8. Scanning electron microscopy (SEM) reveals some aggregations of carbon black particles with a size of 1 μm inside the composite, which was obtained at the mold pressing temperature of 180°C.

Haynes 230 alloy was exposed to reducing and oxidizing environments at 750 °C for 1000 h, simulating the conditions in a reduced temperature solid oxide fuel cell (SOFC). The oxidized specimens were characterized in terms of the oxide morphology, composition and crystal structure. The oxide scale in each environment was identified as Cr2O3 with the existence of Cr2MnO4. Ni remained metallic in the reducing atmosphere, and NiO was detected in the sample exposed to air. The oxide scale is around 1 μm thick after 1000 h of oxidation in both situations. The area specific resistance (ASR) contributed by the oxide scale is expected less than 0.1 Ω cm2 after 40,000 h of exposure when a parabolic oxide growth rate is assumed, demonstrating the suitability of the interconnect application of this alloy in the reduced temperature SOFCs.

A kind of novel ceria electrolyte was examined. Various trivalent oxides were added as co-dopants to Ce 0.8 Gd 0.2 O 1.9 , and their effects on the conductivity of ceria electrolyte were discussed. It has been found that the co-dopant of trivalent oxides of Sm, Nd, La and Y improves the ionic conductivity notably. Furthermore, the fine original powders, co-dopant and higher sintering temperature may hasten the sintering.

A monthly measurement of soil CH4 uptake rate (V(CH4)) in a natural Castanopsis carlesii forest in Wanmulin Natural Reserve of Fujian Province, East China was conducted from March 2010 to February 2011. The VCH4 showed a pronounced seasonal fluctuation, being higher in summer-autumn than in winter-spring, with the maximum value (95.13 microg x m(-2) x h(-1)) in September and the minimum value (9.13 microg x m(-2) x h(-1)) in March. With the increase of soil temperature and moisture, the V(CH4) showed an increasing and a decreasing trend, respectively, but the correlations of the V(CH4) with soil temperature and moisture were not significant. The annual soil CH4 flux of the forest (3.93 kg x hm(-2) x a(-1)) was higher than the average value of global natural forests (2.4 kg x hm(-2) x a(-1)) and of Asian tropical natural forests (2.07 kg x hm(-2) x a(-1)), but lower than that of Asian temperate natural forests (8.12 kg x hm(-2) x a(-1)).