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Slideway is often employed in machine tools for heavy loading. As the rail is associated with the feeding system that required low friction, it is needed to scrap the contact surface in order to improving the lubrication condition and to lower the sliding friction. However, the scraping skill has been passing from mentor manually in the past, thus makes the scraping quality differs and difficult to effectively control the performance of the feeding system. This study develops a systematic approach to investigate the friction characteristics of scraping geometries in particular focuses on the tribological mechanism of wedged texture, in micron level, on the surface through theoretical analysis and numerical simulation. It explores the influences of the geometry configurations on the friction characteristics. The results show that the sliding block with micron level wedged texture can lower the sliding friction while makes itself moving upward. These effects lead to that the reduction of friction with time and finally approaches a steady state.

CO 2 -expanded ethanol (CXE) was used to extract DHA-containing lipids from Schizochytrium sp. with a 35.7 wt% lipid content of dry biomass in a continuous mode. The effects of operation variables such as temperature, pressure, ethanol flow rate and CO 2 flow rate on extraction performance were investigated. Based on a 2 4 -central composite design and response surface methodology, the optimal operating conditions were determined to be a pressure of 6.9 MPa, a temperature of 313 K, an ethanol flow rate of 1 mL/min and a CO 2 flow rate of 6.0 mL/min, providing an extracted lipid yield of 87 wt% over an extraction period of 30 min. Not only the lipid yield obtained using CXE was observed to be significantly greater than those using ethanol and pressurized ethanol as the solvents, but also a lower amount of ethanol and less time were required to achieve the same extraction yield by using CXE.

Friction is a crucial issue for the performance of a machine with sliding mechanism. While the sliding surface is often manually scraped to improve its tribological properties, the quality is not stable nor the efficiency of the scraping process. This study investigated the influences of micro-scale circumferential grooves on the frictional characteristics of a sliding surface through theoretical analysis and numeric simulations. The study found that sliding surface with micro grooves can reduce the friction, compared to plain surface. An in-depth analysis indicated that the slider with micro-scale grooves was uplifted when it slides, thus reduced the sliding friction. Moreover, as the amount of lubricant collected on the grooves increased, the friction force decreased with time and approached a stable condition.

Methyl parben is an often-used anti-septic chemical in personal care products, and its discharge along with domestic sewage or municipal wastewater resulted in the elevated concentration in natural water bodies. To mitigate its impact to the aquatic environment, this study aimed to investigate the methyl paraban degradation by an aerated pebble-bed biofilm system at various hydraulic retention times. The influent methyl paraben concentration was 10 mg/L. The degradation of methyl paraben and synthetic municipal wastewater mixture was evaluated at their respective concentrations of 10 mg/L and 50 mg COD/L. The results indicated that the removal efficiency of BOD at 1 hour hydraulic retention time was 83.7%, and this efficiency increased to 92.54% as the hydraulic retention time increased to 3 hours. The BOD removal efficiencies for methyl paraben and municipal wastewater mixture were higher than those for wastewaters containing only methyl paraben. The influent initial pH was around 4.7 because of hydrolysis of methyl paraben, during which hydrogen ions were released. The pH exhibited an increasing trend as the wastewater travelled through the system. For methyl paraben removal, the efficiencies for wastewater containing only methyl paraben were higher than those for methyl paraben and municipal wastewater mixture. An apparent competition between methyl paraben and municipal wastewater was observed. The methyl paraben degradation followed the 1 st order kinetics.

The protozoan Giardia lamblia differentiates into infectious cysts within the human intestinal tract for disease transmission. Expression of the cyst wall protein (cwp) genes increases with similar kinetics during encystation. However, little is known how their gene regulation shares common mechanisms. DNA topoisomerases maintain normal topology of genomic DNA. They are necessary for cell proliferation and tissue development as they are involved in transcription, DNA replication, and chromosome condensation. A putative topoisomerase II (topo II) gene has been identified in the G. lamblia genome. We asked whether Topo II could regulate Giardia encystation. We found that Topo II was present in cell nuclei and its gene was up-regulated during encystation. Topo II has typical ATPase and DNA cleavage activity of type II topoisomerases. Mutation analysis revealed that the catalytic important Tyr residue and cleavage domain are important for Topo II function. We used etoposide-mediated topoisomerase immunoprecipitation assays to confirm the binding of Topo II to the cwp promoters in vivo. Interestingly, Topo II overexpression increased the levels of cwp gene expression and cyst formation. Microarray analysis identified up-regulation of cwp and specific vsp genes by Topo II. We also found that the type II topoisomerase inhibitor etoposide has growth inhibition effect on Giardia. Addition of etoposide significantly decreased the levels of cwp gene expression and cyst formation. Our results suggest that Topo II has been functionally conserved during evolution and that Topo II plays important roles in induction of the cwp genes, which is key to Giardia differentiation into cysts., Author Summary Giardia lamblia becomes infective by differentiation into water-resistant cysts. During encystation, cyst wall proteins (CWPs) are highly synthesized and are targeted to the cyst wall. However, little is known about the regulation mechanisms of these genes. DNA topoisomerases can resolve the topological problems and are needed for a variety of key cellular functions, including cell proliferation, cell differentiation and organ development in higher eukaryotes. We found that giardial Topo II was highly expressed during encystation. Topo II is present in Giardia nuclei and is associated with the encystation-induced cwp gene promoters. Topo II has typical DNA cleavage activity of type II topoisomerases. Interestingly, overexpression of Topo II can induce cwp gene expression and cyst formation. Addition of a type II topoisomerase inhibitor, etoposide, significantly decreased the levels of cwp gene expression and cyst formation. Etoposide also has growth inhibition effect on Giardia. Our results suggest that Topo II plays an important role in induction of encystation by up-regulation of the cwp gene expression. Our results provide insights into the function of Topo II in parasite differentiation into cysts and help develop ways to interrupt the parasite life cycle.

Localization technology is one of the most important research areas in wireless sensor networks. This paper proposes a set of RF modulation methods to improve the accuracy of localization by utilizing the Receive Signal Strength Indication (RSSI). Two different RF power adjust methods are proposed in this paper. Genetic Algorithm (GA) and Artificial Bee Colony Algorithm (ABC) are used to optimize the location estimation in the indoor environment. Comparisons of the performance of these two methods with two different RF power adjustments are also conducted.