Applied Mechanics and Materials Vols. 556-562

Abstract: A new method for the analysis chemical constituents in jackfruit peel by ultra performance convergence chromatography (UPC²) was developed for the first time. The extraction of jackfruit peel was carried out under classical heating with ultrasonic wave and extracted with ethyl ether. The analytes were separated on an ACQUITY UPC² HSS C18 SB column with a gradient elution (80:20 to 99.8:0.2) of mobile phase consisting of CO₂ and methanol. The result indicated that UPC²/Q-TOF-MS is a simple, rapid, reliable and effective method to analyze the biochemical compounds in jackfruit peel. A total of 65 compounds were identified, including acids, esters, alcohols, and pyrazine, etc.

Abstract: In this study the effect of fucoidan SJP-3 extracted from Stichopus Japonicus was used to evaluate the protective effect on PC12 cells with hypoxia/reoxygenation injury. SJP-3 can stabilize the mitochondrial membrane potential and resistant Cyt-C/mitochondrial apoptotic pathway via increasing the Bcl-2 expression and decreasing expression of the Bax, caspase-3, caspase-9 suggesting that SJP-3 may exert a protective effects on neural cells with hypoxia/reoxygenation injury through the protection of mitochondria, the stability of mitochondrial membrane potential and inhibition of mitochondrial apoptosis pathway.

Abstract: In the hydraulic and pneumatic equipments, the elastomeric O-ring gaskets are widely used to ensure their sealing. The sealing capability of an elastomeric O-ring gasket depends upon the contact stresses that develop between the O-ring and the surfaces with which it comes into contact. In order to increase the strength and service life of the general elastomeric O-ring gasket, this gasket including metal skeleton is gradually applied to the actual product in recent years. In spite of the sealing performance of the elastomeric O-ring gasket has been investigated in many literatures, few information of it is known about the elastomeric O-ring gasket including metal skeleton. If any gasket degrades or fails, the overall operation and performance of the production will be affected. This paper aims to study the contact stresses occurred on the metal skeleton seal structure under the various interference fits with three sectional forms (trapezoid cross section, square cross section and circular cross section). Finite element analysis is used to predict sealing performance of an installed metal skeleton seal, providing a normal force against the sealing surface. Results gained show that the contact stresses occurred on the metal skeleton seal is larger than it generated on the general elastomeric O-ring gasket. Furthermore, the metal skeleton seal possessed trapezoid cross section can produce the maximum contact stress, which will show the best sealing performance among three sectional forms.

Abstract: To develop high wear-resistant protective materials for magnesium alloy, high-silica Al-based alloy modified via P-element was fabricated by DC casting method. Microstructure of ingot samples was observed by using optical microscopy (OM), etc. The results demonstrated that Al-Si-0.01%P alloy with unique microstructure and without defects such as voids and rarefaction might be generated by processing control. Owing to modification by Al-P interalloy, primary crystal silicon phase in hypereutectic Al-Si alloy were refined effectively. Its size in Al-18Si-0.01%P alloy decreased from 50μm to 20μm, and distributed uniquely than that in Al-18Si alloy. Al-P acted as heterogeneous core of primary crystal silicon phase, which was the main mechanism for Al-P interalloy to modify primary crystal silicon in Al-Si alloy.

Abstract: The aim of this paper is to develop a kind of copper matrix self-lubricious material with excellent friction and wear characteristics. The copper-graphite composites reinforced with short copper-coated carbon fibers (CF-C/Cu) were successfully developed using techniques of mechanical alloying, composite plating and hot press vacuum sintering. For comparison, copper-graphite composites without short copper-coated carbon fibers (C/Cu) were made under the same process. The wear testing was carried out using a rapid wear testing machine (M-200).Friction coefficient was measured by a micro-wear tester (UMT).The microstructure, abrasive dust and worn surface of the wear pins on the different condition such as load and wear time were examined by SEM. It was noted that the addition of copper-coated carbon fiber in the Cu-based composites can retard the transformation process which transforms from micro-cutting wear to adhesive wear and delamination. The abrasion loss of the composites with short copper-coated carbon fibers appeared a valley when the load increased from 10N to 30N. It showed that the addition of copper-coated carbon fiber enhanced the anti-friction and anti-wear property of copper matrix composite and better than the sample without carbon fibers.

Abstract: The objective of this work was to examine the influence of carbonation on the microstructure of cement materials. Different materials, which were CEM I mortar and paste, CEM II mortar and paste, were carbonated at 20°C, 65% relative humidity and 20% of CO₂ concentration. The specific surface area and pore size distribution were determined from the method of nitrogen adsorption. The results showed that the materials based on CEM II seemed to be more sensible to a creation of mesoporosity after carbonation than the CEM I based materials. The results of this study also helped to explain why observations in the literature diverge greatly on the influence of carbonation on specific surface area.

Abstract: Based on the investigation data of mercury (Hg) in waters in Jiaozhou bay during time peroids of 1979 to 1985 (absent of 1984), this paper tried to analysis the content, pollution level and theis temporal variations of Hg in Jiaozhou Bay, to reveal the changing trend of Hg, and to provide basis for pollution control of Hg in the bay. Results showed that, during 1979-1985, water in Jiaozhou Bay had been polluted by Hg in certain levels. For seasonal variation, there was a dicreasing trend form summer to winter in 1979, 1981 and 1985, and an increasing trend form summer to winter in 1980 and 1983. For annual variation, there was an obvious decreasing trend of Hg pollution from 1979-1982, while from 1982-1985 an increasing trend occurred. The temporal variation of Hg in Jiaozhou Bay reflects the conflict between economic growth and environmental protection. Having in mind that the environmental carrying capacity of Jiaozhou Bay is not unlimited, and the environmental disruption might finally cause economic loss and disasters to the human, we believe that the dischargd load of Hg should be limited in a suitable amount.

Abstract: Artificial organic polymer flocculants has been widely applied in water treatment; however, disadvantages of nonbiodegradable and poisonous may cause another environmental problem. This paper established an effective water treatment technique using Abelmoschus moschatu (Okra) in combining of glue extraction process and flocculating process, with fully consideration of factors such as treating time, cost, and efficiency. Results showed that ethanol extraction was an effective method for extraction of glue form Okra. After being soaked in distilled water overnight with ratios of material to solvent, and was extracted by ethanol with volume percentage of 50% at stable temperature of 70 °C for one hour, the extraction rate of Okra glue could be as high as 18.38%. The glue usage of 0.015-0.020 g.L^-1 and flocculating time of five minutes could be the optimal usage in treating suspending liquid of kaolin, with the turbidity of 3.0 g.L^-1. The processes are low cost, simple, efficient, and low pollution, having broad application prospects.

Abstract: The cadmium removed from sediment by rhamnolipid biosurfactant was explored in laboratory scale. The results suggest that the biosurfactant can remove cadmium from the sediment efficiently, 40% more than SDS. 200 mg/L rhamnolipid biosurfactant can get 84.02% cadmium removal efficiency from the sediment which contained 0.42 mg/g cadmium. pH affect cadmium removal by rhamnolipid, the best pH was 10. Leaching could also affect cadmium removal, there was a remarkable increasing of cadmium removal efficiency after the second washing, and after 48 h leaching cadmium removal and cadmium absorption got the balance.

Abstract: Diameters of self-assembled micelles were discussed carefully in this paper. When block copolymer was crossed by Eu (III) ions, they could be assembled into micelles. Then diameters of micelles increased with increasing molar ratios of Phen.