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The improvement of the mechanical response of silicon carbide (SiC) coatings on steel substrates when a thin metallic interlayer is included was analyzed. The analysis considered the interfacial reactions and the experimental results obtained from bending experiments performed in a scanning electron microscope (SEM). During bending, in situ observations demonstrated the evolution of cracking in the coatings, with or without debonding. The critical experimental conditions associated with damage mechanisms were determined. The mechanical behavior was related to the deposition parameters and to the interlayer and was compared with analytical calculations. A comparison of the calculated and the experimental results elucidated the interfacial mechanical behavior. [ABSTRACT FROM AUTHOR]

The anatomy, physiology, and biochemistry of the human skin have been studied for a long time. A special interest has been shown in the water permeability of the premature infant's skin, which is known to be an important factor in the maintenance of a controlled water and heat balance. The rate of evaporative heat exchange between the skin surface of a very premature infant and the surrounding incubator air may be so high that evaporative heat loss alone may exceed the infant's total metabolic heat production. However, it has been demonstrated in several investigations published in recent years that basal evaporative water loss can be consistently reduced by increasing the ambient humidity. Nevertheless, the passive humidification system (water reservoir) used in most incubators cannot achieve high and steady humidity levels. In this paper, we propose an active humidification system. The algorithm is based on a combination of optimal control theory and dynamic programming approach. The relative-humidity (R.H.) regulation is performed in range of 35-90% at 33 degrees C with small oscillations (+/- 0.5% R.H.) around the reference value (i.e., prescribed R.H.).

Low-birth-weight neonates should be nursed at thermoneutrality inside incubators. Thermoneutrality control is essential to enhance body growth and to reduce neonatal illnesses and mortality. Guidelines have been published to provide the thermoneutral range, but the recommendations did not always take into account all ambient and physiological parameters influencing thermoneutrality. In most marketed incubators, the heat supply is controlled through convective air flow (closed incubators) or through radiant power density (radiant warmer beds). The heating unit (on/off cycling or adjustable proportional control) is activated by an error signal calculated from the difference between a controlled temperature and a reference value preset by the clinician. The controlled variable can be either the incubator air or the skin temperature of the anterior abdominal region of the neonate. The neonate's size, thermal properties of the mattress and of incubator walls, air temperature and humidity, air velocity, incubator wall temperatures all influence the heat exchanges between the neonate and the surroundings, and, consequently, modify the obtention of thermoneutrality. Moreover, studies of the physiological mechanisms by which the neonate regulates body heat storage suggest that metabolic rate, behavior, vigilance level, nursing care, and heater control processes should also be taken into account. Little attention has been paid to these factors, and incubator performances are often disappointing. This article reviews the different factors that modify thermoneutral condition. An attempt is made to suggest new ways to design equipment incorporating these factors in algorithms controlling heater processes in order to reach the optimal thermal environment in which the neonate should be nursed.

The effects of chlorpromazine, pipotiazine, haloperidol, domperidone, sulpiride and SCH 23390 on the potassium-evoked release of [3H]acetylcholine [( 3H]ACh) were studied in rat striatal slices. All 5 dopamine (DA) antagonists with D-2 blockade efficacy induced an increase of [3H]ACh release whereas the specific D-1 antagonist SCH 23390 was devoid of significant effects. The maximal effect (about 100% increase) was obtained with haloperidol, pipotiazine and sulpiride but not with domperidone and chlorpromazine. Interestingly, sulpiride was found to exert an unexpected marked potency. The comparison of the activities of the 6 compounds on evoked ACh release to their affinities for D-2 receptors [( 3H]N-propylnorapomorphine binding sites) indicates that the pharmacological profile of the dopamine receptor implicated in the regulation of ACh release cannot be superimposed on that of the classical D-2 receptor. Participation of DA presynaptic receptors could however explain the differences in efficacy observed with the compounds studied.