Comparison of hydroxyl radical formation in aqueous solutions at different ultrasound frequencies and powers using the salicylic acid dosimeter

Ultrasonic frequencies of 20 kHz, 382 kHz, 584 kHz, 862 kHz (and 998 kHz) have been compared with regard to energy output and hydroxyl radical formation utilising the salicylic acid dosimeter. The 862 kHz frequency inputs 6 times the number of Watts into water, as measured by calorimetry, with the other frequencies having roughly the same value under very similar conditions. A plausible explanation involving acoustic fountain formation is proposed although enhanced coupling between this frequency and water cannot be discounted. Using the salicylic acid dosimeter and inputting virtually the same Wattages it is established that 862 kHz is around 10% more efficient at generating hydroxyl radicals than the 382 kHz but both of these are far more effective than the other frequencies. Also, it is found that as temperature increases to 42 °C then the total dihydroxybenzoic acid (Total DHBA) produced is virtually identical for 382 kHz and 862 kHz, though 582 kHz is substantially lower, when the power levels are set at approximately 9 W for all systems. An equivalent power level of 9 W could not be obtained for the 998 kHz transducer so a direct comparison could not be made in this instance. These results have implications for the optimum frequencies chosen for both Advanced Oxidation Processes (AOPs) and organic synthesis augmented by ultrasound

Follow the Dotted Line: Composition Portfolio with Commentary.

This research consists of a portfolio of original musical compositions, accompanied by a commentary which examines the aesthetic and technical aspects of each piece and of the body of work as a whole. It traces the development of a mature and original compositional style. The works presented share a focus on the concept of line. This concept is explored in a range of diverse instrumentations (orchestra, choral, solo instrument/voice, chamber ensemble, electronics) and diverse compositional methods (fully-notated scores, graphic scores, devised improvised schemes). The emphasis is on lines that are constrained within a particular pitch register, while being explored fully with regard to other parameters such as rhythm, timbre, and harmony. Another constant is an interest in mathematical structures and how they can be used to create original musical structures. This draws particularly upon the work of Xenakis and Johnson. The original impetus for my research was my analysis of selected works by Feldman and Birtwistle. I will show how these influences helped form my compositional style, and how the style builds upon and departs from these influences. At first, the response to these influences was to compose with an \u27absurdist\u27 aesthetic, in which independent logics are juxtaposed, each of which is internally consistent, but at odds with each other. Over the development of my work during the research process, the emphasis has moved away from a overt consciousness of the absurdist elements and towards a more integrated approach which features a multiplicity of means in which logical lines can be juxtaposed. The discussion of each work begins with a description of the stylistic terrain/field of action within which the work occurs, and an exploration of the musical ideas being explored, then moves on to show how these ideas interact over the course of the work