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High pressure chemistry has traditionally involved applying pressure and increasing temperature until conditions become thermodynamically favorable for phase transitions or reactions to occur. Here, high pressure alone is used as a starting point for carrying out rapid, self-propagating metathesis reactions. By initiating chemical reactions under pressure, crystalline phases, such as gallium nitride, can be synthesized which are inaccessible when initiated from ambient conditions. The single-phase gallium nitride made by metathesis reactions under pressure displays significant photoluminescence intensity in the blue/ultraviolet region. The absence of size or surface-state effects in the photoluminescence spectra show that the crystallites are of micron dimensions. The narrow lines of the x-ray diffraction patterns and scanning electron microscopy confirm this conclusion. Brightly luminescent thin films can be readily grown using pulsed laser deposition.

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ROSE, GUENTER H. (1968).DE-VELOPMENTAL PSYCHOBIOLOCU, l(1): 35-40. T h e development of electrocortical responses evoked by brief, focused monocular light stimulation was studied in 35 lightly anesthetized albino rat pups (Sprague-Dawley strain) between birth and 35 days of age. A definitc sequence of wavcfoi-in changcs occulred during niaturation.T h e initial response at 10 to 11 days of age consisted of a long latency, negative wave. Sulxequently, at approximately 12 days of age, a shorter latency, positive-negative complex appeared. T h e initial, long latency, negative ware decreased rapidly in latency over the next few days until it coalesced with the negative component of the shorlcr latency, positive-negative coniplex at about 15 days of age, resulting in a biphasic positive-negative wave similar l o that recordable in the adult rat. These results are compared and contrasted with a similar sequence observed in the dcveloping kitten, and are discussed in terms of structural, clectrophysiological, and behavioral maturation.The Developiireiit of Visually Evoked Electrocorliccil Responses in the Rat.visual evoked potential vision maturation developmental neurophpsiology electrocortical responses TUDIES of the ontogenesis of spontaneous and evoked electrical activity in the brain are important in that they may reflect concurrent structural and biochemical changes during the period of growth and maturation which in turn can be correlated with behavioral development. I n addition, such neuraldevelopniental studies can be viewed as a technique for the separation of evoked response components during development which may be obscured in atlult records because of temporal overlapping of these components, and which may give cues to the evolvement and involvement of various cortical and subcortical s tru c t u res.T h e maturation of visually evoked electrocortical responses has been studied in the rabbit (Hunt & Goldring, 1951; Marty, 1962), cat (Marty, Containin, & Scherrer, 1959; Ellingson & Wilcott, 1960; Marty, 1962; Rose & Lindsley, 1965, 1966, in press; Rose & Ellington, in press) and dog (Fox, 1967). In most of these studies, particularly those utilizing lightly anesthetized animals, a definite sequence of maturational changes can be seen. This is particularly evident in Received for publication 18 September 1967.Dezlelop i n e?z ta 1 Psycho 6 io logy, 1 ( 1 ) : 3 5-40 ( 1 968) longitudinal studies of the kitten (Rose 8: Lindsley, 1965, in press), where the initial electrocortical response to light flash recorded at 3 to 4 days ol age consists of a long latency, negative wave with peak latency a t approximately 170 msec. Between 6 and 10 days, a shorter latency, negative wave appears. Subsequently, a positive wave of even shorter latency appears. Thus, between 10 and 14 days a complex positive-nega tivenegative wave is in evidence. With increasing age, the long latency, negative .ivave continues to decrease niarkedly in latency, as opposed to the shorter positivenegative complex which reniains relatively ...

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