Wear behavior of wood–plastic composites in alternate simulated sea water and acid rain corrosion conditions

To investigate the effect of alternate simulated sea water and acid rain corrosion on the wear resistance properties of wood–plastic composites, sorghum straw fiber-reinforced polyvinyl chloride (SPVC) composites prepared through extrusion molding were studied. The most detrimental alternating corrosion parameters were evaluated with the orthogonal design method, and the samples were then processed considering superimposed corrosion with the worst parameters. The results show that the worst alternating corrosion parameters were: sea water salinity 3.5% × sea water temperature 55 °C + acid rain pH 2.5 × acid rain temperature 55 °C. Longer alternating corrosion periods resulted in worse physical, mechanical, and thermal properties of the SPVC composites, a PVC matrix that was more easily softened in the frictional environment, and fibers more easily pulled-out to form abrasive particles. Debris of broken or pulled-out fibers moving with high-speed in a high-temperature and high-load frictional contact environment can cause severe abrasive wear.     

Applied Mechanics Problems Accompanying Spacecraft Launches from a Floating Platform and Their Resolution by the Sea Launch Project

The technologies applied by SDO Yuzhnoye to implement the Sea Launch Project are exemplified to describe the recent achievements in designing space launch vehicles. Consideration is given to the loads acting on launch vehicles during long-term sea transportation and prelaunch operations in rough sea. Experimental methods for determining those loads are described, and techniques for reducing them are proposed. Presentation is also given to methods of providing launch safety under conditions of limited space for launch-support equipment and reducing the thermal and vibroacoustic loads on the launcher. The efficiency of the methods described is confirmed by the success of the Sea Launch Project     

东亚季风与东海赤潮

通过分析东亚夏季风在南海的爆发(南海夏季风)与东海赤潮之间的关系,发现南海夏季风爆发后的1～3周内,东海有一次赤潮过程.并对可能的机制进行了讨论,最后提出了利用东亚夏季风在南海的爆发来预报东海赤潮的思路.     

Model and algorithms for multi-period sea cargo mix problem

In this paper, we consider the sea cargo mix problem in international ocean container shipping industry. We describe the characteristics of the cargo mix problem for the carrier in a multi-period planning horizon, and formulate it as a multi-dimensional multiple knapsack problem (MDMKP). In particular, the MDMKP is an optimization model that maximizes the total profit generated by all freight bookings accepted in a multi-period planning horizon subject to the limited shipping capacities. We propose two heuristic algorithms that can solve large scale problems with tens of thousands of decision variables in a short time. Finally, numerical experiments on a wide range of randomly generated problem instances are conducted to demonstrate the efficiency of the algorithms.     

The Distribution of Arsenic Compounds in the Ocean: Biological Activity in the Surface Zone and Removal Processes in the Deep Zone

The vertical profies of inorganic arsenic [As(III)+As(V)], monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA) were investigated at four sampling stations in the Pacific Ocean and a sampling station in the southern Tasman Sea. In addition, the concentrations of those compounds in surface waters of the Pacific Ocean and Tasman Sea have been determined. The vertical profiles of inorganic arsenic showed the low concentrations in both the surface and deep/bottom zones. The depleted concentrations in the surface zone varied from 1000 to 1700 ng dm⁻³ and that in the deep/bottom zone varied from 1300 to 2050 ng dm⁻³. The maximum concentrations that varied from 1500 to 2450 ng dm⁻³ were usually observed at a depth of about 2000 m. Both MMAA and DMAA were observed throughout the water column at sampling stations in the north-western and equatorial regions of the Pacific Ocean. At the sampling station in the central northern Pacific gyre, DMAA was the only methylated arsenic compound observed throughout the water column. On the contrary, at the sampling station in the southern Tasman Sea, the only detected methylated arsenic compound throughout the water column was MMAA. Their vertical profiles showed maximum concentrations in the surface water which abruptly dropped with depth from 0 to 200 m. The concentration in the surface water was close to 10 ng dm⁻³ for MMAA and varied from 27 to 185 ng dm⁻³ for DMAA. At depths greater than 100 m, MMAA and DMAA were at comparable concentrations which varied from 0.7 to 14 ng dm⁻³. The low inorganic arsenic concentration in the surface zone was due to biological activity. This activity resulted in the uptake of As(V) and subsequent reduction and methylation to MMAA and DMAA. DMAA was the main predominant arsenic compound resulting from biological activity in surface waters. The low inorganic arsenic concentrations in the deep and bottom zones were likely to be caused by the adsorption of dissolved inorganic arsenic onto sinking particulates rich in iron and manganese oxides.     

Measurements of trace concentrations of mercury in sea water by stripping chronopotentiometry with gold disk electrode: influence of copper

A stripping chronopotentiometric method, using a rotating gold disk electrode for mercury measurements in sea water is described. Compared with a same method using a stationary gold film electrode, this method has a eight times higher sensitivity and a detection limit of 5 ng l⁻¹ after 10 min deposition time. Moreover, the time needed for gold plating is eliminated. Compared with other electrochemical methods capable of measuring mercury at low concentrations, the present method is more simplified with no degassing step and no need to use a medium-exchange procedure before the stripping step. These characteristics render the method easily practicable on board oceanographic vessels for ‘in situ’ measurements.     

Uranium analysis by neutron induced fissionography method using solid state nuclear track detectors

In this study total twenty samples (eight reference materials and twelve sediment samples) were analysed for their uranium content which is in the range of 1–17 μg/g, by neutron induced fissionography (NIF) method using solid state nuclear track detectors (SSNTDs) in comparison with the results of neutron activation analysis (NAA), delayed neutron counting (DNC) technique or fluorometric method. It is found that NIF method using SSNTDs is very sensitive for analysis of uranium.     

海葵毒素多肽的分离和初步表征

经冻融法提取,丙酮沉淀,SPSephadexC-25强离子交换和HPLCODS反相色谱层析,从海葵(Ac-tiniacari)中提纯到2个新的毒素多肽,命名为RSAPⅢ和RSAPⅣ。经SDS-聚丙烯酰胺凝胶电泳(SDS-PAGE)和基质辅助激光解吸电离飞行时间质谱(MAI-DITOP-MS)鉴定,RSAPⅢ和RSAPⅣ均为单一成分,分子量分别为5327和5310,初步钠通道药理学实验表明,RSAPⅢ对豚鼠心室肌细胞钠通道表现出活性,使钠离子内流减少,起阻滞作用。     

An FT-IR demonstration of the occurrence of satellite bands in the spectra of hydrogen bonds in crystals

OH stretching fundamentals in the spectra of hydrogen-bonded crystals are accompanied by satellite bands due to sum and difference transitions involving one quantum of the OH stretching vibration and one or more quanta of the low-frequency vibration of the hydrogen bond. Such satellites were detected in the FT-IR spectra of two hydrogen-bonded crystals, ice and methanol.NRCC No. 29006     

冰雪路面汽车轮胎摩擦特性研究进展

简要总结了中、高模量材料同冰雪之间的摩擦机理及相关理论，系统分析了影响冰雪路面上橡胶块和轮胎摩擦行为的因素；指出在一定工作条件下，轮胎性能和设计参数，包括胎面胶的低温模量、轮胎结构和胎面花纹等是影响轮胎摩擦牵引力的重要因素，其影响程度取决于运行条件；并就轮胎摩擦特性、全天候轮胎研制及轮胎力主动控制等方面的研究方向和热点提出了建议．