Tam T. Nguyen

Gas/gas and gas/wall energy transfer functions in the multichannel thermal decomposition of chloroethane-2-d1

Abstract The two-channel decomposition of chloroethane-2- d 1 (elimination of HCl and of DCl) has been studied using very low-pressure pyrolysis over the temperature range 975–1200 K (gas/wall collisions only) and over the range 1049–1130 K using Kr, Ne and He as bath gases. Fitting the data by solution of the integrodifferential reaction-diffusion master equation gives CH 2 DCH 2 Cl gas/wall downward energy collision transfer values of 6000-3500 cm −1 (975–1200 K) corresponding to collision efficiencies of 0.9-0.5; the wall is seasoned quartz. These collision efficiencies when applied to data obtained under the same conditions for the one-channel decomposition of CH 3 CH 2 Cl give extrapolated high-pressure Arrhenius parameters in excellent agreement with those obtained from conventional kinetic studies. The pressure-dependent data give gas/gas average downward collision energy transfer values of =600 cm −1 (Kr and Ne) and =700 cm −1 (He) over the observed temperature range (the values increasing slightly with increasing temperatures). The gas/gas energy transfer probability function, rather than being exponential in energy difference, is found to vary approximately as the exponential of the cube of the energy difference between initial and final states; the data are sensitive to this functional form since there is only a small difference between critical energies of each channel. Extrapolated high pressure rate coefficients for CH 2 DCH 2 Cl decomposition are 10 13.2 exp (−237 kJ mol −1 / RT ) s −1 (HCl elimination) and 10 13.1 exp (−244 kJ mol −1 / RT ) s −1 (DCl elimination). Unusual behaviour observed in the pressure dependence is interpreted as being caused by highly quantized structure in the microscopic reaction rate coefficients caused by the lack of low frequency ( −1 ) modes in the activated complexes.

Label-free assessment of endothelial cell metabolic state using autofluorescent microscopy

To examine the process of endothelial cell aging we utilised hyperspectral imaging to collect broad autofluorescence emission at the individual cellular level and mathematically isolate the characteristic spectra of nicotinamide and flavin adenine dinucleotides (NADH and FAD, respectively). Quantitative analysis of this data provides the basis for a non-destructive spatial imaging method for cells and tissue. FAD and NADH are important factors in cellular metabolism and have been shown to be involved with the redox state of the cell; with the ratio between the two providing the basis for an ‘optical redox ratio’.