The development of a low-cost, sensitive colorimetric sensor array for the detection and identification of volatile organic compounds (VOCs) is reported. Using an array composed of chemoresponsive dyes, enormous discriminatory power is possible in a simple device that can be imaged easily with an ordinary flatbed scanner. Excellent differentiation of closely related organic compounds can be achieved, and a library of 100 VOCs is presented. The array discriminates among VOCs by probing a wide range of intermolecular interactions, including Lewis acid/base, Brønsted acid/base, metal ion coordination, hydrogen bonding, and dipolar interactions. Importantly, by proper choice of dyes and substrate, the array is essentially nonresponsive to changes in humidity.

Conclusions: This study suggests that interrupting sitting time with frequent brief bouts of 37 light-intensity activity, but not standing, imparts beneficial postprandial responses that may 38 enhance cardiometabolic health. These findings may have importance in the design of 39 effective interventions to reduce cardiometabolic disease risk. 40

9The school day offers several different time periods that provide varying opportunities for sedentary time (SED) 10 and engagement in physical activity (PA), yet little is known about the PA and sedentary behaviour patterns of 11 boys and girls during these times. The volume, intensity and temporal distribution of SED and PA undertaken 12 by 135 schoolchildren aged 10-14 years, during different segments of the school day: a) school transport, b) 13 morning recess, c) lunch break, d) class time, and e) after school, was explored using tri-axial accelerometry. PA 17PA engagement was similar between sexes during other segments of the day. Conclusion PA patterns appear 18 more beneficial for health in boys during less structured school-based time periods and interventions may 19 therefore target opportunities for girls to be physically active during these times to overcome this observed sex 20 deficit. 22 Keywords 23Children; adolescents; physical activity; sedentary behaviour; accelerometry 24 25

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