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A new screening technique has been developed for the rapid identification of Neurospora crassa mutants that are deficient in nicotinamide adenine dinucleotide glycohydrolase (NADase) and nicotinamide adenine dinucleotide phosphate glycohydrolase (NADPase) activities. Using this procedure, five single-gene mutants were isolated whose singular difference from wild type appeared to be the absence of NAD(P)ase (EC 3.2.2.6). All five mutants were found to be genetically allelic and did not complement in heterocaryons. This gene, nada [NAD(P)ase], was localized in linkage group IV. One of the nada alleles was found to specify an enzyme that was critically temperature sensitive and had altered substrate affinity. Mutations at the nada locus did not affect the genetic program for the expression of NAD(P)ase during cell differentiation, nor did they have a general effect on NAD catabolism. Nada mutations did not have simultaneous effects on other glycohydrolase activities. Tests of dominance (in heterocaryons) and in vitro mixing experiments did not provide evidence that nada mutations alter activators or inhibitors of NAD(P)ase. Thus, the nada gene appears to specify only the structure of N. crassa NAD(P)ase.

Saturated standard cells at temperatures between 20°C and 40°C exhibit a high negative-voltage coefficient with respect to temperature and have required temperature stabilization within ±0.01°C over an extended period to achieve a voltage stability of ±1 ?V. Examination of standard cell data in the vicinity of 0°C, on the other hand, indicated higher voltages and a much lower temperature coefficient. In fact, the cell voltage reaches a maximum and consequently the voltage coefficient is zero at approximately 3°C, and is near zero over a range of several degrees. A cell maintenance temperature of 3°C, therefore, appears the most appropriate operating environment for a saturated cell in order to obtain maximum voltage stability. Heretofore, a convenient, high-stability, maintenance-free temperature bath operating near 3°C has not been available for laboratory use. The utilization of thermoelectricity to cool (Peltier effect) is currently available, and this method has been employed to provide a stable low-temperature ambient for saturated cells. This paper describes a practical air chamber-controller combination with thermoelectric heat pumping designed to test the behavior of saturated cells near 3°C. Details of the thermal and electrical characteristics of the unit will be discussed. Results show a ±0.2°C control is adequate to provide a primary voltage reference with ±1 ?V stability at 3.1°C. Advantages and precautions in maintaining cells at low temperatures will also be presented.

Tonalite (quartz diorite) in southern California has weathered under aa mediterranean climate to depths of more than 30 m. In weathering, the rock was broken up by expansion of biotite as it weathered to vermiculite. The particle density of the resulting fragments is the same as that of the rock (2.75 g/cm 3 ). Biotite comprises 14% of the rock and could produce a linear extensibility of 1.8% in such a uniform, medium-grained material if all the biotite weathered to vermiculite. Measured expansion (1–2%) of the fragmented rock agrees with the predicted value. Other minerals, mostly unweathered, in the rock are: andesine, 56%; hornblende, 13%; quartz, 9%; and orthoclase, 8%. Weathering of the fragmented rock to soil was studied in three kinds of environments in four closely associated soils of a toposequence. Differences in the weathering environments are a result of differences in topographic positions of the soils and resultant differences in soil moisture regimes. A slightly leached environment occurs on hilltop and backslope positions. These position are occupied by Ustochrepts and Haploxeralfs. B horizons of these soils have base saturations of less than 90%, lack salts in soil solution, and contain little exchangeable magnesium and sodium. In this environment vermiculite and kaolinite are formed from weathered biotite. No crystalline clay minerals were detected in the other primary minerals. A high sodium environment occurs in footslope positions. Natrixeralfs occupying these positions are slightly leached in upper parts but accumulate some soluble ions, especially sodium, magnesium, and in places carbonates and amorphous silica in lower parts. In this environment biotite weathers to vermiculite and kaolinite, andesine and hornblende to montmorillonite. The third environment is a base-rich environment found in areas of subdued relief and somewhat restricted drainage. The Pelloxererts in this position have significant amounts of soluble salts and large amounts of extractable magnesium and sodium. Minor amounts of secondary carbonates and amorphous silica accumulate below their sola. In the base-rich environment biotite weathers to vermiculite and montmorillonite, andesine and hornblende to a beidellite-montmorillonite. The beidellite-montmorillonite formed from the andesine is dioctahedral. Its structural formula is (Si 7.44 Al 0.56 )(Al 2.62 Mg 0.73 Fe 0.61 Ti 0.08 ) O 20 (OH) 4 (M + 0.95, K + 0.05 ) and it has a C.E.C. of 119 mequiv./100 g. The stability sequence for primary minerals from least to most stable is biotite, andesine, hornblende, quartz.

Through stereoscopic study of aerial photographs many features of the vegetation and also ground features can be directly identified. This has a practical application in mapping vegetation and soils in upland areas of California. This paper describes how vegetation types can be identified by analysis of the features visible on aerial photographs. It then describes how soil mapping is facilitated by photo interpretation of ground features, land form, and vegetation.

Scale model testing of 90 degree turn ejector systems for rocket engine altitude simulation

A compact blackbody source with an operating range of -40 degrees C to + 60 degrees C, utilizing thermoelectric heat pumping for uniform and stable temperature control, has been developed. The blackbody radiator (target) consists of a blackened honeycomb cavity array coupled to four matched, two-stage (cascade type) thermoelectric modules. This array, located within a temperature-regulated baffle system, produces a blackbody of high emissivity (0.995) with small thermal gradients over the source area (65 cm(2)). Heat pumping of the target and baffles is controlled, independently, by two interference-free, proportional regulators which provide linear thermal control in both the heating and cooling modes of operation. Additional features of this blackbody source include excellent stability and rapid response to input temperature changes. Provisions are made for temperature monitoring at five locations on the target and at the center of each of the four baffle units. Performance characteristics and test results obtained in nonabsorbing atmospheres and under vacuum conditions are presented, as are the details of construction and operation.