The niobium (columbium)-palladium constitution diagram

The Nb-Pd system was investigated over the entire composition range by metallography and X-ray diffraction analysis. The solubility limits of terminal and intermediate phases and solidus temperatures were determined. α-Nb dissolves ∼36 at. pct Pd at. 1520°C and ∼20 at. pct Pd at 800°C; α-Pd dissolves ∼31 at. pct Nb at 1610°C and ∼18 at. pct Nb at temperatures below 1500°C. The presence of three intermediate phases NbPd₂ (MoPt₂-type), α-NbPd₃ (TiAl₃-type), and β-NbPd₃ (β-NbPd₃-type) was confirmed; NbPd₂ melts at 1610°C and one of the NbPd₃ phases transforms at the same temperature into α-Pd solid solution which melts at 1625°C. In addition, an approximately equiatomic high-temperature phase α-NbPd with a homogeneity range of ∼11 at. pct was found which melts at 1520 to 1565°C and probably is an extension of and isomorphous with the α-Pd solid solution. Five three-phase reactions are described, and crystal chemical relationships are discussed. D. P. PARKER formerly with MIT . R. C. MANUSZEWSKI formerly with the ADAHF Research Unit at NBS.     

Simpson's paradox and the analysis of memory retrieval.

According to Simpson's paradox (E. H. Simpson, 1951), if 2 or more contingency tables are collapsed into one, the resulting table may show a relationship between variables different from those shown by any of the original tables. Thus, a positive or negative relationship or stochastic independence may be shown by every component table, but be masked, in the collapsed table, by one of the other characteristics. This paradox has implications for the analysis of memory retrieval, particularly when the focus of interest is the relationship between success and failure on 2 retrieval attempts. Several recent issues in the memory literature are discussed in this connection, with emphasis on confounding effects of S differences, item differences, and S-item interactions. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Model for coal oxidation kinetics. 1. Reaction under chemical control

Rate expressions are presented to describe the oxidation of coal in a fixed-bed reactor under mild conditions, i.e. conditions which are useful in pretreatment for gasification. A model for chemical control is developed based upon the concept of a triple-path coupled burn-off adsorption site. The model incorporates the effects of temperature, oxygen partial pressure, and coal surface area, and is the first to account for the product distribution of gaseous C0₂, CO, and H₂O, as well as oxygen deposited on the coal surfaces. The overall rate of oxidation is limited by the amount of reactive surface area in the coal particles and is assumed to be reduced as a result of the deposited oxygen which covers potentially reactive sites. This model differs significantly from the previously formulated model of Kam, A. Y. et al. Chem. Eng. Sci. 1976, 31, 815 which postulated external mass transfer control.     

Colposcopy and the management of cervical intraepithelial neoplasia

The stable, bound iodine in the thyroid colloid of Triturus helveticus has been studied with the electron microprobe. Some animals show a normal development. Others are accidentally neotenic due to certain ecological conditions. The values of punctate iodine concentrations (CPI) have been computed and expressed in relative units (counts/s). The mean CPI per lumen is very variable from one follicle to another in the same thyroid section. During normal development, the mean CPI per animal is generally higher in metamorphosing individuals than in larvae. During development with neoteny, the mean CPI per animal attains high values if the larval state is maintained in its totality; the CPI decreases in partially metamorphosed animals, but increases again after metamorphosis. The amount of halogen contained in the thyroid colloid has been computed in relative units (colloid iodine pool). Throughout normal development, the pool remains small if the animals have not attained the adult state. In increases considerably in entirely larval neotenic newts, decreases during metamorphosis but increases afterwards. In totally neotenic newts, the thyroid gland receives only a low hypophyseal stimulation and reacts as the thyroid gland of various hypophysectomized Urodeles. Our results pose the problem as to whether TSH regulates the transepithelial iodine flows, which permit the expansion of the colloid iodine pool, when this hormone is secreted at a very low levels.     

Open matrix very low density explosive formulations

In this paper, we have established the feasibility of preparing open-cell matrix explosive charges by two entirely different techniques, one based on a     

A New High-Quality PWM AC Drive

The development and realization of an economic low- powered ac drive system which sets new standards in reducing environmental pollution is reported with applications in industrial and office equipment. Pulsewidth modulation (PWM) digital techniques are used for accurate three-phase waveform synthesis using an asynchronous ultrasonic carrier and metal-oxide semiconductor field effect transistors (MOSFET's) for the power switching elements.