The effect of yttrium and thorium on the oxidation behavior of Ni-Cr-Al alloys

The effect of quaternary additions of 0.5% Y, 0.5 and 1.0% Th to a base alloy of Ni-10CR-5Al on the oxidation behavior and mechanism was studied during oxidation in air over the range of 1000 to 1200 C. The presence of yttrium decreased the oxidation kinetics slightly, whereas, the addition of thorium caused a slight increase. Oxide scale adherence was markedly improved by the addition of the quaternary elements. Although a number of oxides formed on yttrium containing alloys, quantitative X-ray diffraction clearly showed that the rate-controlling step was the diffusion of aluminum through short circuit paths in a thin layer of alumina that formed parabolically with time. Although the scale adherence of the yttrium containing alloy was considerably better than the base alloys, spalling did occur that was attributed to the formation of the voluminous YAG particles which grew in a mushroom-like manner, lifting the protective scale off the subrate locally. The YAG particles formed primarily at grain boundaries in the substrate in which the yttrium originally existed as YNi9

Letter from William Douglass

Letter from William Douglass to Virginia Williams, regarding failed speculations.https://scholarsjunction.msstate.edu/mss-williams-papers/1156/thumbnail.jp

Letter to Virginia Williams

Letter from W. L. Douglass to Virginia Williams, regarding his financial troubles and other family matters.https://scholarsjunction.msstate.edu/mss-williams-papers/1010/thumbnail.jp

Bling without blood? The role of natural resources in civil war

This study answers the research question: what factors determine the onset and duration of civil wars involving natural resources? This case study analysis uses determinants extracted from several quantitative studies to examine the role of natural resources in civil war. This study compares resource politics in the Democratic Republic of the Congo and the Republic of Botswana from independence to the early 2000s. The Congo officially became embroiled in a civil war in 1996 and then in 1998. During this same period another resource-rich country, Botswana was able to parlay resource abundance into positive development indicators. However, Botswana\u27s political and economic weaknesses help exclude some of the factors commonly associated with the role of resources in civil war. For example, Botswana depended heavily upon resource exports. It also failed to develop sectors outside of the mining sector. In addition, it was a de facto single-party country.Still, Botswana remained peaceful. Scholars believe that at the end of the Cold War rebels had to seek their own funding sources since superpower assistance was no longer available. This discourse suggests that we can understand more about rebel mobilization since the story is no longer clouded by Cold War politics. The findings in this study suggest that the discourse has not moved as rapidly as previously thought. The discourse is now in its second generation. The first generation was characterized by economic explanations (as a departure from a history of political explanations). The second generation has come full circle, back to political explanations. Despite these developments, a number of operationalization problems inhibit a clear understanding of causality. This study recommends new approaches to understanding the role of resources in conflicts. Currently, scholars over-determine the role of natural resources in civil war.For example, a set of unique historical circumstances merged to create the conditions for civil wars in the Congo in 1996 and 1998. The distinctions between resource conflicts and conflicts caused by other political reasons are not clear in some of the quantitative studies

Reaction of Boron Trichloride with Methoxyamine Hydrochloride

Boron trichloride and methoxyamine hydrochloride were reacted in refluxing chlorobenzene and again in a refluxing mixture of chlorobenzene and chloroform. Procedures for handling and analyzing samples under anhydrous conditions are discussed. Evidence is given for the formation of B-trichloro-N-trimethoxyborazine in the chlorobenzene/chloroform system

A determination of the prevalence of certain harmful safety misconceptions among seventh and eighth grade pupils

Thesis (Ed.D.)--Boston University

The Twin Astrographic Catalog (TAC) Version 1.0

A first version of the Twin Astrographic Catalog (TAC) of positions for 705,679 stars within $-18^{\circ} \le \delta \le 90^{\circ}$ has been produced. The sky coverage of the TAC is complete to over 90\% in that area. The limiting magnitude is about B=11.5. Positions are based on $4912$ plates taken with the U.S. Naval Observatory Twin Astrograph (blue, yellow lens) at epochs 1977--1986. The TAC is supplemented by proper motions which are obtained from a combination with a re--reduced Astrographic Catalog (AC). Some AC zones are available now and a complete northern hemisphere is expected by fall 1996. Proper motions of almost all TAC stars will be generated as the AC work progresses. The average precision of a catalog position is 90 mas per coordinate at epoch of observation. A large fraction of that error is introduced by the currently available reference stars. The inherent precision of the TAC data is considerably better. The precision of the proper motions is currently 2.5 to 4 mas/yr. Magnitude--dependent systematic errors have been found and preliminarily corrected. The final reduction of this plate material will be performed with the Hipparcos catalog in 1997. The TAC is about 3 times more precise than the PPM or ACRS in the northern hemisphere at current epochs and contains about 3 times more stars. The TAC has a higher star density than the Tycho catalog and provides independent, high precision positions for a large fraction of the Tycho stars at an epoch about 10 years earlier than the Tycho mean epoch. The TAC version 1.0 data are released as the AC zones become available. For latest information, look at the US Naval Observatory World Wide Web page http://aries.usno.navy.mil/ad/tac.html.Comment: 22 pages LaTex, accepted by AJ, scheduled for Nov., no figures provided, needs aasms4.st

The effect of silicon and manganese on the oxidation of Ni-20Cr and Co-20Cr alloys

Silicon and manganese effects on nickel-chromium and cobalt-chromium alloy oxidatio