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Abstract.Comparative spectroscopic study including the photosensitizers of pyropheophorbide methyl ester (PPME) and pyropheophorbide a (PPa) was performed to study their photodynamic activity. The investigated photosensitizers in a homogeneous system of dimethylformamide (DMF) are not photostable upon irradiation. The photobleaching efficiency of PPa is higher than that of PPME. Combining these results with the data obtained by measuring the singlet oxygen quantum yield and the hydroxyl group generation, it was revealed that the photobleaching efficiency could be correlated with the singlet oxygen quantum yield and the hydroxyl group production of the photosensitizer.

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Abstract. Oil and grease (O&G) are usually found in kitchen waste water. O&G are poorly soluble in water and can cause serious problems during the wastewater treatment. Adsorption is a fundamental process in the treatment of kitchen waste water and very economical. Activated carbon is the most effective adsorbent for this application. Therefore, the aim of the current study is to determine the potential of four materials (i.e. sand, gravel, carbonised grass (CG) and clay powder) as filter media for O&G removal. The CGs were originated from "Elephant Grass" and it is a fast growing plant with significant potential as carbon. The clay acts as a magnet, drawing the oil molecules out of the water and causing them to attach to the surfaces of the clay. In the current study, two filters were developed with different media materials to get the best percentage removal. Filters 1 and 2 were filled with sand, gravel and CG, and sand, gravel, CG and powder clay, respectively. Three samples were taken during peak hour between April and May 2016. The initial O&G concentration varied from 101.37 mg/l to 248.30 mg/l and the final concentration varied from none to 22.57 mg/l for both filters. The percentage removal (%) of O&G were between 90.9 and 97.3 (Filter 1) and between 94.3 and 100 (Filter 2). Overall, both filters could efficiently remove O&G in the waste water and the quality of the carbonised grass proved to be as good as carbon produced from other traditional sources.

SummaryThis paper attempted to isolate variables that govern concrete spalling when exposed to a hydrocarbon fire. The influence of specimen size was investigated by studying 4 specimen sizes consisting of cylinders, columns, and panels. Three aggregate sizes, 7 mm, 14 mm, and 20 mm were used in the concrete mixes to determine their effect on concrete spalling. Influence of aggregate type on concrete spalling was also investigated. Forty-two different specimens were considered in this investigation. Concrete spalling was quantified as nominal spalling depth, which has been presented as a new way of quantifying the degree of concrete spalling. The results indicated that specimen size did have an effect on the spalling of concrete under hydrocarbon fire exposure and that nominal spalling depth of concrete increases as the specimen size increases.Aggregate size effect was evident when the maximum aggregate size increased from 7 mm to 20 mm, and explosive spalling was more severe for specimens with small size aggregates. Specimens with 14-mm aggregate size showed inconsistent results and the spalling behavior witnessed was more random and sporadic. The type of aggregate used has no clear bearing on concrete spalling given both aggregates had similar linear expansion profiles. However, concrete is susceptible to a less known phenomenon termed spalling in fire. Spalling of concrete in fire is the dislodgement of small pieces of concrete up to 50 mm (popping out) from the surface of the concrete, often explosive in nature. If the degree of spalling is significant, the load bearing capacity of the concrete member can be reduced due to (1) reduction in its cross-sectional size, and (2) rapid increase in temperatures of the reinforcement. more predominate when concrete is subjected to hydrocarbon fire due to the rapid heating rise. 5 The moisture content of the specimen has been reported to be a significant factor which governs spalling. 6High levels of moisture content generate the buildup of pore water pressures.A number of key researchers have studied the factors which govern spalling including thermal stresses, pore pressures, thermal dilation, and incompatibility between cement paste and aggregate. 7-10 The "moisture-clog mechanism" due to the buildup of pore water pressures has been widely accepted as the main mechanism causing concrete spalling. 9,[11][12][13][14][15][16][17] Contrary to this, spalling caused by differential thermal gradients within the concrete element has also been widely accepted to explain the spalling phenomenon. crack of critical size and orientation increases with the volume of the specimen. [22][23][24] This is in agreement with Bazant's size effect law (SEL) theory, which states that as the specimen size increases, the compressive strength decreases. 23,25,26 In relation to spalling, the "size effect" phenomenon has a direct effect on the moisture content of the concrete specimen, the rate of in situ heating, and water mass loss. | EXPERIMENTAL PROGRAMMEThe materials used in this investig...