Preparation of nanocomposite alumina–Sn2Fe by mechanical alloying

Nanocomposites of Al₂O₃ and Sn₂Fe were prepared by ball milling alumina with elemental Sn and Fe. Samples were prepared with molar ratios of Al₂O₃ and Sn₂Fe of 1:1 and 2:1. Materials produced in this way have been characterized by X-ray diffraction techniques as well as ⁵⁷Fe Mössbauer effect spectroscopy as a function of milling time. The nanosized grains show a distribution of particle sizes along with some residual elemental components. Preliminary investigations of electrochemical cells indicate that these materials show promise as possible electrodes for Li-ion cells.     

From Highly Purified Boron Nitride to Boron Nitride‐Based Heterostructures: An Inorganic Precursor‐Based Strategy

The current approaches used to fabricate hexagonal boron nitrides (h‐BN) from boron trioxide and urea always results in contamination of the h‐BN product with carbon/oxygen. Thus, discovering a facile way of mass producing high‐purity h‐BN remains a challenge. A simple yet highly efficient thermal treatment approach to large‐scale fabrication of nanoporous h‐BN with high yield, high purity, and high crystallinity is described using NaNH₂ and NaBH₄ as the oxygen‐ and carbon‐free precursors. The unique properties of inorganic metal salts, i.e., high melting point and strong electrostatic interaction with carbon substrates, render this strategy suitable for the production of homogeneous h‐BN/mesoporous carbon and h‐BN/carbon nanotube heterostructures of high crystallinity, high h‐BN dispersity, and with a strong interfacial effect. These unique features make them promising candidates for supercapacitor applications, resulting a significantly enhanced specific capacitance. This study provides new insight into the fabrication of high‐purity h‐BN and h‐BN‐based heterostructures thus expanding their application in the field of energy storage and transformation.     

On the bias of Huffcutt and Arthur's (1995) procedure for identifying outliers in the meta-analysis of correlations.

This study documents how the use of A. I. Huffcutt & W. A. Arthur's (1995) sample adjusted meta-analytic deviancy (SAMD) statistic for identifying outliers in correlational meta-analyses results in inaccuracies in mean r. Monte Carlo simulations found that use of the SAMD resulted in the overidentification of small relative to large correlations as outliers. Furthermore, this tendency to overidentify small correlations was found to increase as the magnitude of the population correlation increased and resulted in mean rs that overestimated the population correlation. The implications for meta-analysts are discussed, and 2 possible solutions are offered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Design of particulate composites for optical applications

This paper reviews the basic theoretical approach to describing light scattering in filled materials with nearly matching refractive indices (Rayleigh-Gans-Debye Theory). The modifications necessary to handle high filler concentrations (interparticle interference and multiple scattering) are included empirically. The primary result of this analysis is an expression for the optical transmission of a polymer composite as a function of particle size, volume fraction, composite thickness, and refractive index difference between the components. The angular dependence of the scattering is included so that scattered light which falls within the aperture of the transmission detector can be accounted for, Particular attention is given to including the temperature dependence of the refractive index and the effect of fillers on the thermal expansion properties of the polymer matrix in order to predict the temperature range over which the composite will be optically useful. Similarity to analyses of the Christiansen filter is discussed.     

Echocardiographic practice in a large metropolitan area

A survey performed concerning echocardiography in a metropolitan area. Of 110 hospitals in the area, 62 reported having echocardiographic facilities. Echocardiographic physicians and/or technicians from 41 of these hospitals responded to questionnaires designed to determine the following: (1) educational background and credentials of technicians, (2) average salaries of technicians, (3) role of the physician and technician in the performance and reporting of echocardiograms, (4) volume, cost, and method of storage of echocardiograms, and (5) number and type of echocardiographic units in use. Our data suggest various trends, including a lack of formal training among technicians, the prevalence of cardiologists-internists as directors of echocardiographic facilities, the performance of echocardiograms by cardiology fellows in only 46% of institutions with cardiology training programs, and the widespread projected availability of cross-sectional echocardiographic capability within the next two years.     

Failure to detect moderating effects: Is multicollinearity the problem?

We show that Morris, Sherman, and Mansfield's (1986) contention that multicollinearity causes ordinary least squares–moderated multiple regression (OLS–MMR) to underestimate the importance of moderator effects is incorrect for their own data. Multicollinearity was reduced to the point that it was negligible by transforming predictor variables and moderator variables to standard scores prior to computing cross-product terms. We show the resulting cross-product terms both mathematically and empirically to have near-zero correlations with standardized predictors and moderators. Yet, as Arnold and Evans (1979) showed, the results of OLS–MMR are unchanged by this linear transformation of scale. Morris et al's (1986) finding of significant moderator effects when using principal-components regression (PCR) is probably a result of some artifact of PCR. (PsycINFO Database Record (c) 2010 APA, all rights reserved)