Addition of silicon improves oxidation resistance of nickel based superalloys

Specific weight changes of nickel-base superalloy B-1900 and B-1900 + 1% Si specimens were tested at 1273 K. B-1900 was losing weight at an increasing rate due to spalling of oxide scale while B-1900 + 1% Si was still gaining weight at low, nearly constant rate. Similar comparison in weight change was observed for specimens tested at 1373 K

Computer user's guide for a chemically reacting viscous shock-layer program

A description is given of the computer code for predicting viscous shock-layer flows over nonanalytic blunt bodies (Program VISLNABB) for hypersonic, low Reynolds number flows. Four specific and one general body geometries are considered. In addition to sphere-cones, cylinder wedges and geometries defined in tabular form, options for hyperboloids and paraboloids are included. Details of the theory and results are included in a separate engineering report. The program, subroutines, variables in common, and input and output data are described. Listings of the program code, output data for a sample case, and the input data for this sample case are included

Hypersonic ionizing air viscous shock-layer flows over nonanalytic blunt bodies

The equations which govern the viscous shock-layer flow are presented and the method by which the equations are solved is discussed. The predictions of the present finite-difference method are compared with other numerical predictions as well as with experimental data. The principal emphasis is placed on predictions of the viscous flowfield for the windward plane of symmetry of the space shuttle orbiter and other axisymmetric bodies which approximate the shuttle orbiter geometry. Experimental data on two slender sphere-cones at hypersonic conditions are also considered. The present predictions agreed well with experimental data and with the past predictions. Substantial differences were found between present predictions and more approximate methods

A finite difference method for predicting supersonic turbulent boundary layer flows with tangential slot injection

An implicit finite difference method has been applied to tangential slot injection into supersonic turbulent boundary layer flows. In addition, the effects induced by the interaction between the boundary layer displacement thickness and the external pressure field are considered. In the present method, three different eddy viscosity models have been used to specify the turbulent momentum exchange. One model depends on the species concentration profile and the species conservation equation has been included in the system of governing partial differential equations. Results are compared with experimental data at stream Mach numbers of 2.4 and 6.0 and with results of another finite difference method. Good agreement was generally obtained for the reduction of wall skin friction with slot injection and with experimental Mach number and pitot pressure profiles. Calculations with the effects of pressure interaction included showed these effects to be smaller than effects of changing eddy viscosity models

Effects of silicon additions on oxidation and mechanical behavior of the nickel-base superalloy B-1900

Test specimens with nominal additions of Si were tested in oxidation, thermal fatigue, sulfidation, tension, and stress rupture, and were also extensively studied metallographically. Alloy B-1900 modified with 0.6- or 1.2-wt% Si exhibited oxidation resistance equivalent to that of aluminide-coated B-1900 during cyclic, high-gas-velocity oxidation tests. Resistances to thermal fatigue and sulfidation were improved by the Si additions, but were not superior to aluminide-coated B-1900. Stress-rupture tests at 1000 C of specimens given the standard heat treatment to simulate an aluminide coating cycle showed Si to be detrimental. However, application of another heat treatment increased the rupture life of the alloy with 0.6-wt% Si to that of the unmodified B-1900 given the standard heat treatment

“O Stop and Tell Me, Red Man”: Indian Removal and the Lamanite Mission of 1830-31

In 1830-1831, Mormon missionaries were sent out to proselytize Native Americans—an effort called the “Lamanite Mission.” While this event has been scrutinized multiple times over and in a variety of ways, the Native Americans themselves are most often either considered passive characters in the narrative or ignored completely. However, understanding the circumstances of those Native Americans leading up to the Lamanite Mission, during the era of Indian Removal, can give a deeper understanding of the early Mormon mission which has heretofore been ignored. Understanding Indian Removal not only explains why the Seneca, Wyandot, Shawnee, and Delaware people were located as they were when Mormon missionaries arrived in 1830-1831 but can also give possible explanations as to why those Native Americans reacted to the message of Mormonism as they did. Each of the four Native American groups, while experiencing many of the same trials during the late eighteenth and early nineteenth centuries, also underwent their own, unique issues which help to give more detail to the Lamanite Mission and the reaction of Native Americans to the first Mormon missionaries. Finally, by looking at the circumstances of the Native Americans themselves, the issue of ignoring or sidelining the indigenous people in the narrative of the Lamanite Mission can, at least in part, be rectified

The effect of peripheral curve modifications on the forces which hold the contact lens on the eye using gas permeable contact lenses

The experiment consisted of removing a contact lens from the subject\u27s cornea following modification of the contact lens. Modification consisted of flattening the peripheral curve. The question that we hoped to answer was whether or not the amount of force required to remove the contact lens would increase as the peripheral curve was modified. Our contention was that while flattening the peripheral curve effectively loosens the lens the amount of force required to remove the lens from the contact will increase. The experiment showed that in 2 out of 3 subjects there was an increase in the adhesive forces acting on the lens between monocurve and the first peripheral curve. Subsequent flattening of the peripheral curve resulted in a gradual decrease in adhesion force with each modification to flatten the peripheral curve. We would expect such a result since a monocurve has less surf ace area contact between l ens and cornea than a bicurve. However, the data do not support the thought that the adhesion force will increase with each successive flattening of the peripheral curve

Voyager 1 Encounter with the Saturnian System

An overview of the Voyager 1 encounter with Saturn is presented, including a brief discussion of the flight, trajectory, science plan formulation, and highlights of the results described in the subsequent reports

Subcutaneous delivery of sumatriptan in the treatment of migraine and primary headache

Subcutaneous sumatriptan is an effective treatment for pain from acute migraine headache, and can be used in patients with known migraine syndrome and in patients with primary headaches when secondary causes have been excluded. In limited comparative trials, subcutaneous sumatriptan performed in a manner comparable with oral eletriptan and intravenous metoclopramide, was superior to intravenous aspirin and intramuscular trimethobenzamide-diphenhydramine, and was inferior to intravenous prochlorperazine for pain relief. The most common side effects seen with subcutaneous sumatriptan are injection site reactions and triptan sensations. As with all triptans, there is a risk of rare cardiovascular events with subcutaneous sumatriptan and its use should be limited to those without known cerebrovascular disease and limited in those with known cardiovascular risk factors and unknown disease status. In studies of patient preference and tolerability, the subcutaneous formulation has a faster time of onset and high rate of efficacy when compared with the oral formulation, but the oral formulation appears to be better tolerated. It is important to consider the needs of the patient, their past medical history, and what aspects of migraine treatment are most important to the patient when considering treatment of acute migraine or primary headache. Subcutaneous sumatriptan is a good first-line agent for the treatment of pain from acute migraine headaches and primary headaches