The paper presents a micro polymerase chain reaction (PCR) device consisting of a miniature thermal cycler incorporating Pt thin layers used as heater and temperature sensors, screen-printed on a ceramic plate and a disposable PDMS part with a 1 μl chamber. Using a heating power of only 0.3 W at 95 • C and 1.5 W during heating transitions, the device can provide a 7.7 • C s −1 heating rate. For temperature control, a two-degree-of-freedom proportional-integral-derivative controller in conjunction with an anti-windup algorithm was designed and implemented. The obtained performances (such as the use of the maximum/minimum power level during almost all of the transition time, overshoots and undershoots below 0.1 • C, very short settling time with no oscillation, steady error less than ±0.05 • C and excellent robustness against the process changes) exceed those published so far. In addition, the proposed controller is much simpler to implement and tune in comparison to other previously described controllers. A dynamical correction of the difference between the sensor and chamber temperatures is introduced and several profiles for set-point shaping are proposed and compared. The delayed preshaped profile, based on the inverse of the corresponding transfer function, was found to give the best results. Forced convection cooling is handled as a heat switch providing a cooling rate of 6.6 • C s −1 while preserving the low power requirement for heating. With the device described cycle times of 12 s (if the dwell times are not considered) are possible. PCR amplification with 32 cycles was successfully carried out in less than 25 min.

Laser sparks that were built with high-peak power passively Q-switched Nd:YAG/Cr(4+):YAG lasers have been used to operate a Renault automobile engine. The design of such a laser spark igniter is discussed. The Nd:YAG/Cr(4+):YAG laser delivered pulses with energy of 4 mJ and 0.8-ns duration, corresponding to pulse peak power of 5 MW. The coefficients of variability of maximum pressure (COV(Pmax)) and of indicated mean effective pressure (COV(IMEP)) and specific emissions like hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NO(x)) and carbon dioxide (CO2) were measured at various engine speeds and high loads. Improved engine stability in terms of COV(Pmax) and COV(Pmax) and decreased emissions of CO and HC were obtained for the engine that was run by laser sparks in comparison with classical ignition by electrical spark plugs.

No abstract

No abstract

An electronic electroscope with a special design for demonstrations and experiments on static electricity is described. It operates as an electric charge sniffer by detecting slightly charged objects when they are brought to the front of its sensing electrode. The sniffer has the advantage of combining high directional sensitivity with a logarithmic bar display. It allows for the identification of electric charge polarity during charge separation by friction, peeling, electrostatic induction, batteries, or secondary coils of power transformers. Other experiments in electrostatics, such as observing the electric field of an oscillating dipole and the distance dependence of the electric field generated by simple charge configurations, are also described.