Effect of dislocation substructures on fatigue fracture

The effect of dislocation substructures on fatigue is explored within the following categories: a) the dislocation substructures produced by cycling in annealed material and the effect of cycling on substructures introduced extraneously before cycling; b) hight and low strain fatigue fracture, expressed in terms of Coffin-manson or stress-life plots; and c) the effect of substructure on the mechanisms of crack nucleation and propagation. Usually, cycling is very effective in rearranging substructures introduced extraneously, especially at high strains. Consequently, there is little effect of the substructures on fatigue fracture except under some circumstances at low strains, and also if the agent of introducing the initial substructures has had an effect on the fracture process, for example, by opening cracks at inclusions. Dislocation substructure, however formed, is not significant,per se, to fatigue fracture except in acting as a source of plastic deformation. This paper is based on a presentation made at a symposium on “Mechanical-Thermal Processing and Dislocation Substructure Strengthening,” held at the Annual Meeting in Las Vegas, Nevada, on February 23, 1976, under the sponsorship of the TMS/IMD Heat Treating Committee.     

Parameters affecting critical currents in superconducting Nb3Al

A.c. susceptibility measurements made on samples of Nb₃Al have shown that, even after extensive heat-treatments, significant amounts of degraded A15 phases are present. This low critical field material, resulting from vacancies on the niobium chains, limits the current carrying capacity of the bulk sample. The indication is that under favourable conditions the critical current density of Nb₃Al could equal or be superior to that of Nb₃Sn.     

The use of response patterns to improve item scoring.

This study compared the validity of 2 methods of scoring the Minnesota Vocational Interest Inventory. One method used keys developed in the usual manner by selecting items that differentiated between specific occupational groups and a reference group of tradesmen-in-general. The other method used keys developed by selecting items that were part of response patterns that differentiated between criterion and reference groups. 3 occupational keys were developed and cross-validated: painter, printer, and electrician. Results showed that the keys were about equal in their ability to separate criterion from reference groups, but the key developed from response patterns used far fewer items. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Galvanic skin response to Negro and white experimenters.

"Forty white male subjects participated in what was nominally a word association test with GSR being recorded. Two Es, one Negro and one white, alternated in making simulated readjustments of a dummy apparatus attached to the S's left wrist… . A highly significant difference in GSR response to the two Es was found. A significant adaptation process was manifested in lessening degrees of response during the successive contacts." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Copolymers of maleic anhydride-14C and vinyl acetate as standards in an automated titration method for combined anhydride

Copolymers of maleic anhydride and vinyl acetate containing 6 to 54 wt-% maleic anhydride were prepared in both toluene and methyl ethyl ketone by employing carboxyl-¹⁴C-labeled anhydride of demonstrated radiochemical purity. The standard copolymers thus prepared were used as reference materials in development of an automated titrimetric method for combined anhydride that had a standard deviation of 1.7 wt-% at an anhydride level of approximately 50%. The semimicrotechnique described is based on dissolution of the polymer in methyl ethyl ketone–aqueous alkali, addition of an aliquot of this solution to a slight excess of hydrochloric acid, and back titration of the excess of acid with standard alkali. The technique effectively prevents hydrolysis of the acetate groups of the copolymer.     

Synthesis and characterization of isocyanate-terminated polyurethane prepolymers

Using statistically designed experiments, seven variables were investigated to determine their effect on the physical and mechanical properties of isocyanate-terminated polyurethane prepolymers. The choice of catalyst (dibutyltin diacetate, T-1, or stannous octoate, T-9) along with the ratio of diol to triol were found to most significantly control the prepolymer properties. Other variables such as reaction temperature, reaction time, and order of polyol addition did not affect the system. In comparing the two catalysts, T-9 was found to be concentration sensitive, yielding low-viscosity prepolymers at the lower catalyst level and higher viscosity, unstable materials at the higher catalyst level. No evidence was found to show concentration sensitivity of T-1. A series of prepolymers based on varying ratios of diol to triol were synthesized, and their physical and mechanical properties are reported.     

DIFFERENTIATION OF YEASTS BY ELECTROPHORETIC METHODS

An examination of the esterase isoenzymes reacting with α-naphthyl acetate indicated five types of electrophoretic pattern in 94 strains of 54 species of 15 yeast genera. Groups classified according to esterase patterns agreed with accepted taxonomic groups, but there were no differences of obvious value for routine identification of separate species of yeasts. Strictly aerobic yeasts produced up to four bands of esterase activity; facultative anaerobes produced two lines or only one. Proteins detected by staining with trifalgic acid after electrophoresis formed identical patterns from all yeasts tested.     

Pueblo’s Oxygen Steelmaking Operations

The Colorado Fuel & Iron Corp.’s basic oxygen steelmaking facility was described in the September 1961 issue of Journal of Metals. This paper presents operating data obtained since the plant’s start-up on July 11, 1961, with particular emphasis on the production of high-carbon steels.