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We investigated the effect of incision and sternotomy on the auditory evoked potential (AEP) and EEG, to try to predict a haemodynamic response to incision or sternotomy using the AEP and EEG in 41 patients undergoing cardiac surgery during propofol and alfentanil anaesthesia. The AEP and EEG were recorded before incision, between incision and sternotomy, and after sternotomy. Peak latencies and amplitudes of AEP peaks V, Na, Pa, Nb, Pb and Nc were determined. From the EEG the median, spectral edge and peak power frequencies, and percentages of delta, theta, alpha and beta power were calculated. Each patient was classified as responsive, equivocally responsive or unresponsive to incision or sternotomy based on increase in arterial pressure and heart rate on incision and sternotomy. Before incision, Nb and Pb latency and propofol concentration were higher for unresponsive patients but heart rate and median frequency before incision were lower. After sternotomy, Pa and Nb amplitude, peak power frequency and percentage alpha power were higher, and percentage theta power lower for responsive patients. Pa latency was higher after sternotomy for unresponsive patients. Using a combination of heart rate, arterial pressures and features derived from the AEP (all recorded before incision), the occurrence of a response to incision could be predicted in individual patients with a sensitivity of 85%, positive predictive accuracy of 63% and total accuracy of 72%. We conclude that AEP are more sensitive to pain stimuli than spectral features of the spontaneous EEG. In addition, the AEP may help in predicting inadequate anaesthesia.

We conclude that the described method of automatic detection and removal of artifacts in AEP recordings effectively improves the quality of the resulting AEP waveform, without excessive rejection of artifact-free signal periods. The signal variables used in this method seem appropriate for distinguishing artifact-free signal periods from periods containing artifacts for the types of artifact that were studied.

Boiling of a pure fluid inside the rotor-stator cavities of a stator-rotor-stator spinning disc reactor (srs-SDR) is studied, as a function of rotational velocity x, average temperature driving force DT and mass flow rate / m . The average boiling heat transfer coefficient h b increases a factor 3 by increasing x up to 105 rad s 21, independently of DT and / m . The performance of the srs-SDR, in terms of h b vs. specific energy input , is similar to tubular boiling, where pressure drop provides the energy input. The srs-SDR enables operation at > 10 5 Wm 23R , yielding values of h b not practically obtainable in passive evaporators, due to prohibitively high pressure drops required. Since h b is increased independently of the superficial vapor velocity, h b is not a function of / m and the local vapor fraction. Therefore, the srs-SDR enables a higher degree of control and flexibility of the boiling process, compared to passive flow boiling. V C 2016 American Institute of Chemical Engineers AIChE J, 00: 000-000, 2016 Keywords: evaporation, spinning disc reactor, heat transfer, intensification IntroductionForced convection boiling processes are widely encountered in the (chemical) process industry, e.g., in evaporative separations, in refrigeration cycles and in withdrawing heat of highly exothermic reactions.1,2 Intensification of boiling heat transfer reduces the required heat exchange area, which reduces the capital costs and the space requirements. Moreover, it allows the application of a lower temperature driving force DT, which is thermodynamically favorable and essential in utilization of low-grade heat streams using vapor recompression. Intensification of flow boiling is realized by increasing the boiling heat transfer coefficient h b , and by efficient removal of the formed vapor phase from the heat exchanging surface.The heat transfer in forced convection boiling occurs via two parallel mechanisms, viz. nucleate boiling and convective evaporation. [3][4][5][6][7] Both mechanisms contribute to the overall value of h b . Nucleate boiling is the formation of vapor bubbles at the heat exchanging surface, due to a high local superheating of the liquid. The formation of bubbles induces convection on a microscale, which leads to high values of h b , similar to pool boiling. 1,8,9 Convective evaporation is the macroscale fluid forced convection, with evaporation occurring at the liquid-vapor interface. Typically, at a high heat flux q 00 , obtained at a high DT, and a low vapor superficial velocity v G , h b is dominated by the nucleate boiling mechanism, resulting in a high value of h b . At a high vapor velocity (at a high mass flow rate / m or a high vapor fraction x G ), nucleate boiling is suppressed due to a more effective withdrawal of the local superheat by forced convection, 10,11 resulting in lower values of h b , compared to the nucleate boiling regime. 5,6 In this convective evaporation regime, h b increases with increasing turbulence in the liquid and decreasing distance between the heat exchanging ...

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