Design and evaluation of thin metal surface insulation for hypersonic flight

An all-metal insulation was studied as a thermal protection system for hypersonic vehicles. Key program goals included fabricating the insulation in thin packages which are optimized for high temperature insulation of an actively cooled aluminum structure, and the use of state-of-the-art alloys. The insulation was fabricated from 300 series stainless steel in thicknesses of 0.8 to 12 mm. The outer, 0.127 mm thick, skin was textured to accommodate thermal expansion and oxidized to increase emittance. The thin insulating package was achieved using an insulation concept consisting of foil radiation shields spaced within the package, and conical foil supports to carry loads from the skin and maintain package dimensions. Samples of the metal-insulation were tested to evaluate thermal insulation capability, rain and sand erosion resistance, high temperature oxidation resistance, applied load capability, and high temperature emittance

Properties and stabilization of an extracellular α-glucosidase from the extremely thermophilic archaebacteria Thermococcus strain AN 1: enzyme activity at 130°C

An extracellular α-glucosidase from the thermophilic archaebacterium Thermococcus strain AN1 was purified 875-fold in five steps (Hiload Q-Sepharose, phenyl Sepharose, HPHT-hydroxyapatite, gel filtration and Mono Q chromatography) with a yield of 4%. It is a monomer with a molecular mass of about 60 kDa and a pI around 5. At 98°C, the purified enzyme in buffer has a half-life around 35 min, which is increased to around 215 min in presence of l% (w/v) dithiothreitol and 1% (w/v) BSA. Dithiothreitol (1%, w/v) and BSA (0.4%, w/v) also substantially increase the enzyme activity. The Km at 75°C is 0.41 mM with pNP-α- -glucopyranoside as substrate. The substrate preference of the enzyme is: pNP-α-D-glucoside > nigerose > panose > palatinose > isomaltose > maltose and turanose. No activity was found against starch, pullulan, amylose, maltotriose, maltotetraose, isomaltotriose, cellobiose and β-gentiobiose. A variety of techniques including immobilization (e.g., on epoxy and glass beads), chemical modification (cross- and cocross-linking) and the use of additives (including polyhydroxylic molecules, BSA, salts, etc.) were applied to enhance stability at temperatures above 100°C. The half-life could be increased from about 4 min at 110°C to 30–60 min at 130°C in presence of 90% (w/v) sorbitol, 1% (w/v) dithiothreitol and l% (w/v) BSA, and by cocross-linking with BSA in the presence of 90% (w/v) sorbitol. The stabilized enzyme showed good activity at 130°C

McMeasuring Diplomacy: Modeling Determinants of International Public Opinion Toward the United States

This paper is concerned with modeling the extent to which external factors affect political attitudes toward the United States. The data is concerned with how economic, governance, and cultural factors impact attitudes regarding the favorability of the United States in the eyes of the world, and testing the empirical implications of Thomas Friedman’s Golden Arches Theory of Conflict Prevention. The results suggest a strong negative relationship between a country being a Muslim majority country and the favorability of the United States in that country, a positive relationship between the perceived “Voice and Accountability” of a country and the favorability of the United States in that country. Although the study finds no relationship between trade in general and the favorability of the United States—the study does find that trade with domestically producing firms of the United States increases the favorability of the United States abroad

Linear Filament Array Sheet for EUV Production.

An EUV radiation source that generates a sheet of a liquid target material that has a width that matches the desired laser spot size for good conversion efficiency and a thickness that matches the laser beam/target interaction depth. The EUV source includes a reservoir containing a pressurized cryogenic liquid target material. such as liquid Xenon. The reservoir also includes an array of closely spaced orifices into a vacuum chamber as separated liquid stream filaments of the target material that define the sheet. The liquid streams freeze to form an array of frozen target filaments. A laser beam is directed to a target area in the vacuum chamber where it irradiates the stream of filaments to create a plasma that emits EUV radiation

Development and Quality of Life in Cities

Articulating the goals of economic development and defining quality of life has drawn the attention of influential thinkers from Socrates to Sen. Attempts to quantify and compare economies as they pertain to these concepts have largely focused on the macroeconomy. In this study, the Metropolitan Development Index is created to measure development and quality of life in large, urban areas in the United States. The researchers then test the sensitivity of city rankings to the data used in constructing the index. These tests indicate that the index is a substantive conception of development and quality of life. Additionally, the index is positively correlated with both economic prosperity and an individual’s desire to reside in areas that offer higher levels of development and quality of life

High Temperature EUV Source Nozzle

A nozzle for a laser-plasma EUV radiation source that provides thermal isolation between the nozzle body and the target material flowing therethrough. A target delivery tube is provided that extends through the nozzle body. The delivery tube has an expansion aperture positioned behind an exit collimator of the nozzle body. The delivery tube is made of a low thermal conductivity material, such as stainless steel, and is in limited contact with the nozzle body so that heating of the nozzle body from the plasma does not heat the liquid target material being delivered through the delivery tube. The expansion aperture has a smaller diameter than the exit collimator

Remediation of Acid Rock Drainage in a Changing Climate: Assessment of Bulkhead Closures and Long-term Water Quality Trends in the Colorado Mineral Belt

Acid rock drainage (ARD) produces low pH, high metal concentration waters into receiving waters down-gradient from oxidizing sulfide minerals. ARD can degrade habitat, poison aquatic organisms, and lead to the transport of heavy metals long distances down streams. This dissertation investigates ARD responses to three different perturbations: decadal-scale response to targeted AMD remediation strategies including source material removal and bulkhead installation, decadal-scale response to climate change, and month-scale response to bulkhead implementation in draining mine adits. The goal of these investigations is to advance the understanding of ARD responses to anthropogenic and natural changes to help optimize remediation actions and future management of ARD affected waters. First, monitoring water quality data were paired with USGS flow gage data and an estimator was used to estimate higher temporal frequency records of in-stream water quality in three ARD affected alpine watersheds. These data were then analyzed for trends in water quality corresponding with timing of treatment implementation. Two streams record decreased zinc concentrations following treatment implementation; one stream records a substantial increase in zinc concentration following a shift from active treatment to passive, bulkhead-oriented treatment strategies. A second study investigated trends in background ARD in response to local climate change at 24 headwater stream sites across the Colorado Mineral Belt. Zinc concentration increased at 75% of sites over the period of record (10-40 years) by 2-6 fold and sulfate concentration increased at 96% of streams. The final study presented in this dissertation investigates the short-term impacts of a bullhead closure on water quality in receiving waters. Results indicate that sulfate and heavy metal concentrations decreased during the test closure buy 65-68%. However, the short duration of the test closure and the relatively small volume of water impounded during the test closure (&lt;1% of the estimated storage volume) leave uncertainty over longer-term impacts of the bulkhead test. Collectively, the studies presented in this dissertation expand the knowledge of ARD responses to both remediation-based changes and natural climate driven changes on the catchment scale.</p

Liquid Sprays As the Target for A Laser-Plasma EUV Light Source

A laser-plasma EUV radiation source that generates larger liquid droplets for the plasma target material. The EUV source forces a liquid, preferably Xenon, through a nozzle, instead of forcing a gas through the nozzle. The geometry of the nozzle and the pressure of the liquid through the nozzle atomizes the liquid to form a dense spray of droplets. Because the droplets are formed from a liquid, they are larger in size, and are more conducive to generating EUV radiation. A condenser is used to convert gaseous Xenon to the liquid prior to being forced through the nozzle