Contamination of diuron in coastal waters around Malaysian Peninsular

The use of antifouling paints to the boats and ships is one among the threats facing coastal resources including coral reefs in recent decades. This study reports the current contamination status of diuron and its behaviour in the coastal waters of Malaysia. The maximum concentration of diuron was 285 ng/L detected at Johor port. All samples from Redang and Bidong coral reef islands were contaminated with diuron. Temporal variation showed relatively high concentrations but no significant difference (P > 0.05) during November and January (North-East monsoon) in Klang ports (North, South and West), while higher levels of diuron were detected during April, 2012 (Inter monsoon) in Kemaman, and Johor port. Although no site has shown concentration above maximum permissible concentration (430 ng/L) as restricted by the Dutch Authorities, however, long term exposure studies for environmental relevance levels of diuron around coastal areas should be given a priority in the future.     

伊洛瓦底海豚被追逐时回声定位信号特征变化的初步分析

本文的研究基于文莱湾浅水域的一头野生伊洛瓦底海豚水声定位信号的调查数据。在记录期间,有一艘渔船突然开启发动机,惊扰了其附近的一头伊洛瓦底海豚,接着渔船开始两次连续追逐海豚。这期间海豚回声定位信号的变化情况被记录下来。当伊洛瓦底海豚受惊吓被追逐时,信号的声压级、每分钟嘀嗒声信号串的发生次数、每个嘀嗒声信号串中的脉冲个数和平均脉冲间隔都发生了相应的变化。平均的脉冲间隔在事件发生的瞬间立即增大,并在追逐期间呈现轻微下降趋势。脉冲间隔的增大对应着探测距离的增加,代表着海豚对未知区域的探索能力,制约着它的逃离速度。数据记录结果的分析表明,伊洛瓦底海豚会根据外界干扰对发出的回声定位信号进行调整,改变自己对潜在危险的探查能力。分析结果同时提醒我们需要随海豚生存环境的噪声进行管理,避免突然的发动机操作或者追逐它们。     

Emission of scalar particles from cylindrical black holes

We study quantum tunneling of scalar particles from black strings. For this purpose we apply WKB approximation and Hamilton-Jacobi method to solve the Klein-Gordon equation for outgoing trajectories. We find the tunneling probability of outgoing charged and uncharged scalars from the event horizon of black strings, and hence the Hawking temperature for these black configurations.     

Osmotic suction of highly plastic clays

This paper presents a study on osmotic suction of compacted highly plastic clays. Two different types of bentonite (i.e. Calcigel and a bentonite from India called herein as Indian bentonite) were used. Squeezing technique was utilized to obtain soil pore-water of the specimen. Using relationship between electric conductivity and osmotic pressure of salt solution, osmotic suction of soil pore-water was obtained. Additional tests (i.e. total and matric suction using filter paper method and swelling pressure using constant volume swelling pressure test) were performed. The results show that osmotic pressure of soil pore-water obtained decreases by increasing squeezing pressure. Based on experimental result, osmotic suction of the specimen is osmotic pressure of the first drop of extracted soil pore-water. An empirical method was suggested to determine the squeezing pressure in squeezing technique. In addition, roles of osmotic suction in thermo-hydro-mechanical behavior of highly plastic clays were presented and discussed in the paper.     

Effectiveness of zinc application to minimize cadmium toxicity and accumulation in wheat (Triticum aestivum L.)

Cadmium (Cd) is a highly toxic heavy metal and its presence in soil is of great concern due to the danger of its entry into the food chain. Among many others, proper plant nutrition is an economic and practicable strategy for minimizing the damage to plants from Cd and to decrease Cd accumulation in edible plant parts. The study was carried out to compare the effectiveness of soil and foliar applications of zinc (Zn) to minimize Cd accumulation in wheat grains. The results revealed that the exposure of plants to Cd decreased plant growth and increased Cd concentration in the shoots and grains of wheat, when compared with unexposed plants. Foliar application of 0.3 % zinc sulfate solution effectively decreased Cd concentration in wheat grains. Foliar application of Zn at a suitable concentration can effectively ameliorate the adverse effects of Cd exposure and decrease the grain Cd concentration of wheat grown in Cd-contaminated soil.