Aerospike thrust chamber program

An existing, but damaged, 25,000-pound thrust, flightweight, oxygen/hydrogen aerospike rocket thrust chamber was disassembled and partially repaired. A description is presented of the aerospike chamber configuration and of the damage it had suffered. Techniques for aerospike thrust chamber repair were developed, and are described, covering repair procedures for lightweight tubular nozzles, titanium thrust structures, and copper channel combustors. Effort was terminated prior to completion of the repairs and conduct of a planned hot fire test program when it was found that the copper alloy walls of many of the thrust chamber's 24 combustors had been degraded in strength and ductility during the initial fabrication of the thrust chamber. The degradation is discussed and traced to a reaction between oxygen and/or oxides diffused into the copper alloy during fabrication processes and the hydrogen utilized as a brazing furnace atmosphere during the initial assembly operation on many of the combustors. The effects of the H2/O2 reaction within the copper alloy are described

Developing Self-Regulated Learning Behaviors in Online Learning Environments - A Conceptual Framework for Inclusion

This paper outlines the conceptual framework of an inclusion initiative for programs serving secondary students from economically challenged communities. It proposes the use of distance learning technologies to afford these students access to learning resources, experiences, and environments in STEM. This paper addresses concerns with a complex duality of environmental factors: the environments in which these students are reared and currently reside; and the alteration to the environments in which they “traditionally” learning. It outlines a process where components participating in the online learning experiences contribute to the development of the motivational and learning strategies to overcome environmental conditions and achieve academic excellence

Thermal degradation kinetics of aromatic ether polymers

Fluorinated polymers of substantial high performance such as perfluorocyclobutyl (PFCB) and fluorinated aryl vinyl ether (FAVE) polymers can readily be synthesized by thermal [2+2] cyclopolymerization as a melt or by classical polycondensation. These fluoropolymers naturally possess high thermal and chemical resistance, low conductivity properties, and other mechanical properties. In this work, a method using 0th order kinetics is proposed and thermal degradation studies were conducted on six different aromatic ether-based polymers to gauge trends in activation energy barrier and differences in thermal stability by 0th order degradation kinetics. The activation barrier (E_a) obtained can give accurate insight into the stability of the polymer based only on structure for external applications. Activation energies ranging from 17 to 41 kcal/mol were obtained for the various polymers. Overall, this study provides an established method using TGA for thermal stability studies through 0th order kinetics that can be potentially used for future lab applications

Interactions Among Root Disease Pathogens and Bark Beetles in Coniferous Forests

At least two interactions exist among these important groups of organisms: (1) that of the bark beetles as vectors; and (2) that of root pathogens as predisposers of trees to beetles. Bark beetles might be important vectors of root decay fungi, but there is as yet little supporting evidence. However, some beetles may have primary roles as vectors on non-decay pathogens such as Leptographium wageneri, L. procera, and L. terebrantis. Possible of greater importance is predisposition of trees by the pathogens. Evidence continues to build supporting the relationship, and there is a suggestion that beetles can maintain a relatively high populations level in areas with above average disease activity. A few studies have shown effects on host physiology that may be related to increased susceptibility to bark beetles, and one of two have even suggested effects on primary attraction. A review of the literature in both forest pathology and forest entomology shows a serious deficiency in research on these interactions and their significance in resource management

Characterization of T24D14(ok809) a putative alpha-1,2 glucosyltransferase in C elegans and detailed structural analysis of the lipid linked oligosaccharide pathway via MSN

The formation of glycoconjugates, lipids or proteins covalently linked to carbohydrate groups in biological systems, is a universal process in every form of life studied to date. The carbohydrate moiety of glycoconjugates range in complexity from single monomers to intricately branched structures containing over a dozen residues. This complexity is further compounded by the incorporation of several different monomer types with varying linkage positions and branching patterns. The number of possible carbohydrate structures is astronomical providing significant challenges to characterize, study, and catalog these molecules. Furthermore, assigning biological consequence can be a daunting task considering the numerous interactions caused by the infinite number of biochemical reactions. Methods often focus on one type of glycoconjugate or even a single structure help understand such complexity. The projects described here will attempt to examine the role of the lipid-linked oligosaccharide (LLO) pathway in the formation of N-glycans from a genetic and structural perspective

Thermally isolated deployable shield for spacecraft

A thermally isolated deployable shield for spacecraft is provided utilizing a plurality of lattice panels stowable generally against the craft and deployable to some fixed distance from the craft. The lattice panels are formed from replaceable shield panels affixed to lattice structures. The lattice panels generally encircle the craft providing 360 degree coverage therearound. Actuation means are provided from translating the shield radially outward from the craft and thermally isolating the shield from the craft. The lattice panels are relatively flexible, allowing the shield to deploy to variable diameters while retaining uniform curvature thereof. Restraining means are provided for holding the shield relatively tight in its stowed configuration. Close-out assemblies provide light sealing and protection of the annular spaces between the deployed shield and the crafts end structure