液相色谱-质谱法测定水中氨基甲酸酯类农药及其代谢物

建立了直接测定水中10种氨基甲酸酯类农药及其代谢物的超高效液相色谱-质谱分析方法。该方法对水样无需进行富集处理,水样过滤后就可以直接测定。实验结果表明:测定液中各氨基甲酸酯类农药及其代谢物的质量浓度与离子对峰面积在质量浓度0.5～1 000.0μg/L内具有良好的线性关系;方法检出限为0.1～5.0μg/L;加标回收率91%～103%;相对标准偏差为2%～5%。该方法具有简便快捷、灵敏度高的特点。     

偕胺肟合铁(Ⅲ)纤维对α-萘酚的吸附

以腈纶纤维为原料络合Fe3+制得偕胺肟合铁(Ⅲ)纤维,用其处理α-萘酚溶液,研究了偕胺肟合铁(Ⅲ)纤维对α-萘酚的吸附工艺条件和吸附动力学参数。实验结果表明,偕胺肟合铁(Ⅲ)纤维对α-萘酚的最佳吸附工艺条件为pH=3.0、吸附温度313.15K和吸附时间45min。在最佳工艺条件下,偕胺肟合铁(Ⅲ)纤维对α-萘酚的吸附在所研究的α-萘酚浓度范围内符合Freundlich等温吸附方程。未达到饱和吸附前,偕胺肟合铁(Ⅲ)纤维对α-萘酚的吸附符合一级反应动力学特征。     

Mode choice model for vulnerable motorcyclists in Malaysia

OBJECTIVE: In developing countries, motorcycle use has grown in popularity in the past decades. Commensurate with this growth is the increase in death and casualties among motorcyclists in these countries. One of the strategic programs to minimize this problem is to reduce motorcyclists exposure by shifting them into safer modes of transport. This study aims to explore the differences in the characteristics of bus and motorcycle users. It identifies the factors contributing to their choice of transport mode and estimates the probability that motorcyclists might change their travel mode to a safer alternative; namely, bus travel. METHODS: In this article, a survey of 535 motorcycle and bus users was conducted in seven districts of Selangor state, Malaysia. A binary logit model was developed for the two alternative modes, bus and motorcycle. RESULTS: It was found that travel time, travel cost, gender, age, and income level are significant in influencing motorcyclists' mode choice behavior. The probability of motorcycle riders shifting to public transport was also examined based on a scenario of a reduction in bus travel time and travel cost. CONCLUSIONS: Reduction of total travel time for the bus mode emerges as the most important element in a program aimed at attracting motorcyclists towards public transport and away from the motorcycle mode.     

Characteristics of large cooking oil pool fires and their extinguishment by water mist

Large cooking oil pool fires, occurring in industrial oil cookers, present a severe hazard to food processing plants due to their size and the large amount of hot oil involved. This paper reports a series of full-scale fire experiments conducted in a large industrial oil cooker mock-up. The characteristics of large cooking oil pool fires and the effect of oil depth and hood position in the oil cooker on fire growth were studied. The use of water mist for extinguishing large oil pool fires and their extinguishing performance under different discharge pressure and with different types of water mist systems were investigated. Experimental results showed that the cooking oil underwent a substantial expansion in volume during heating. The fires developed quickly once the oil auto-ignited. The fire growth rate was affected by the oil depth in the pan and the hood position in the oil cooker. The water mist fire suppression systems effectively extinguished large cooking oil fires and prevented them from re-igniting. Their extinguishing performance was determined by the type of water mist system, discharge pressure and hood position in the oil cooker.     

Differences and similarities of gas and dust explosions: A critical evaluation of the European ‘ATEX’ directives in relation to dusts

Explosive gas mixtures and explosive dust clouds, once existing, exhibit similar ignition and combustion features. However, there are two basic differences between dusts and gases which are of substantially greater significance in design of safety standards than these similarities. Firstly, the physics of generation and up-keeping of dust clouds and premixed gas/vapour clouds are substantially different. This means that in most situations where accidental explosive gas clouds may be produced quite readily, generation of explosive dust clouds would be highly unlikely. Secondly, contrary to premixed gas flame propagation, the propagation of flames in dust/air mixtures is not limited only to the flammable dust concentration range of dynamic clouds. The state of stagnant layers/deposits offers an additional discrete possibility of flame propagation.

The two European Directives 94/9/EC (1994) and 1999/92/EC (1999) primarily address gases/vapours, whereas the particular properties of dusts are not addressed adequately. Some recent IEC and European dust standards resulting from this deficiency are discussed, and the need for revising the two directives accordingly is emphasized.     

Off-site emergency scenario, a case study from a LPG Bottling Plant

After Bhopal disaster, emergency planning in an industrial area has become inevitable. The off-site emergency plan is an integral part of any major hazard control system. Boiling Liquid Expanding Vapour Explosion (BLEVE) leads to fatal consequences. This paper highlights some salient features of the emergency scenario, which ultimately leads to fireball with enormous pressure wave all around.     

Experimental Verification of the Computerized Method for Work Space Optimization in Conditions of Static Work

The aim of this study was to verify a theoretical model for upper extremity work space optimization. In order to do that, experimental studies were conducted in which two parameters of the electromyography (EMG) signal were analyzed: AMP (amplitude calculated as Root Mean Square) and SZC (coefficient of the slope of the regression line between time and Zero Crossing values). Values of forces in muscles (parameter MOD) were calculated from theoretical studies. A comparison of experimental (AMP, SZC) and theoretical (MOD) parameters was performed by analyzing the coefficient of correlation between those parameters and differentiation of muscular load according to external load value. Analysis showed that the theoretical and experimental results are in step, which means that the developed model can be used for upper extremity work space optimization.     

Disparity of a Seat Cushion and Its Influence on Postural Control

Properties of supporting surfaces of a seat have an influence on postural control. Centre of pressure (COP) displacement parameters reflect both the balance controlling process and movements of the centre of a mass of entire body. The subjects of the study were 9 healthy men. A seat cushion was examined with a 2-force platform setup. Force exertion at a seat pan and feet and COP displacement at a seat pan were measured to analyse postural control. Analysis of variance determined the differences in postural control depending on a cushion type among the subjects. Significant differences in COP displacement parameters were in COP trajectory length, medio-lateral COP displacement and COP velocity. The results of the study showed that foam cushion ensures better postural control.