Modifications of a Composite-Material Combustion Chamber

Two short reports discuss modifications of a small, lightweight combustion chamber that comprises a carbon/carbon composite outer shell and an iridium/ rhenium inner liner. The first report discusses chamber design modifications made as results of hot-fire tests and post-test characterization. The Books & Reports 32 NASA Tech Briefs, June 2005 modifications were intended to serve a variety of purposes, including improving fabrication, reducing thermal-expansion mismatch stresses, increasing strength-to-weight ratios of some components, and improving cooling of some components. The second report discusses (1) the origin of stress in the mismatch between the thermal expansions of the Ir/Re liner and a niobium sleeve and flange attached to the carbon/ carbon shell and (2) a modification intended to relieve the stress. The modification involves the redesign of an inlet connection to incorporate a compressible seal between the Ir/Re liner and the Nb flange. A nickel alloy was selected as the seal material on the basis of its thermal-expansion properties and its ability to withstand the anticipated stresses, including the greatest stresses caused by the high temperatures to be used in brazing during fabrication

A Rapid and Computationally Inexpensive Method to Virtually Implant Current and Next-Generation Stents into Subject-Specific Computational Fluid Dynamics Models

Computational modeling is often used to quantify hemodynamic alterations induced by stenting, but frequently uses simplified device or vascular representations. Based on a series of Boolean operations, we developed an efficient and robust method for assessing the influence of current and next-generation stents on local hemodynamics and vascular biomechanics quantified by computational fluid dynamics. Stent designs were parameterized to allow easy control over design features including the number, width and circumferential or longitudinal spacing of struts, as well as the implantation diameter and overall length. The approach allowed stents to be automatically regenerated for rapid analysis of the contribution of design features to resulting hemodynamic alterations. The applicability of the method was demonstrated with patient-specific models of a stented coronary artery bifurcation and basilar trunk aneurysm constructed from medical imaging data. In the coronary bifurcation, we analyzed the hemodynamic difference between closed-cell and open-cell stent geometries. We investigated the impact of decreased strut size in stents with a constant porosity for increasing flow stasis within the stented basilar aneurysm model. These examples demonstrate the current method can be used to investigate differences in stent performance in complex vascular beds for a variety of stenting procedures and clinical scenarios

Method of Heating a Foam-Based Catalyst Bed

A method of heating a foam-based catalyst bed has been developed using silicon carbide as the catalyst support due to its readily accessible, high surface area that is oxidation-resistant and is electrically conductive. The foam support may be resistively heated by passing an electric current through it. This allows the catalyst bed to be heated directly, requiring less power to reach the desired temperature more quickly. Designed for heterogeneous catalysis, the method can be used by the petrochemical, chemical processing, and power-generating industries, as well as automotive catalytic converters. Catalyst beds must be heated to a light-off temperature before they catalyze the desired reactions. This typically is done by heating the assembly that contains the catalyst bed, which results in much of the power being wasted and/or lost to the surrounding environment. The catalyst bed is heated indirectly, thus requiring excessive power. With the electrically heated catalyst bed, virtually all of the power is used to heat the support, and only a small fraction is lost to the surroundings. Although the light-off temperature of most catalysts is only a few hundred degrees Celsius, the electrically heated foam is able to achieve temperatures of 1,200 C. Lower temperatures are achievable by supplying less electrical power to the foam. Furthermore, because of the foam s open-cell structure, the catalyst can be applied either directly to the foam ligaments or in the form of a catalyst- containing washcoat. This innovation would be very useful for heterogeneous catalysis where elevated temperatures are needed to drive the reaction

Open-front Systems

Dave Serfling and his family live in Preston, Minnesota, which is just north across the border from Decorah. Dave graduated from ISU in 1981 in farm operations. Serflings have a 50 sow farrow-to-finish operation and 80 cows they feed out. They also have sheep, and they own about 350 acres. They love Iowa so much, Dave\u27s wife even works in Iowa, so thanks for helping the economy. (laughter) Steve Williams and his wife live in Villisca, in Page County. Steve is a 1988 ISU business graduate. He has a total livestock operation with beef and a farrow-tofeeder pig operation. He feeds out a few. There are some interesting family ties and partnerships in Page County, and now his operation\u27s up to about 300 sows in a very productive and unique arrangement, which we\u27ll hear more about. Greg Vogel represents the ISU AG 450 Farm, which is located southwest of Ames , about a mile. This is actually a student-managed farm, and many of you are familiar with that concept that the students really manage it, for better or for worse. And they suffer all the advantages and perils of pure agriculture. Greg is the farm operator. He\u27s also an ISU grad (ag business, 1978) and finished a master\u27s in ag business in 1994. The farm is about 950 acres, and they have 200 sows out there. They run both outdoor and confmement operations. Last we\u27ll hear from my good friend, Dick Thompson. Dick and Sharon, of course, farm in Boone County. Dick and Sharon recently were recognized as the 1996 Farm Agricultural Leaders of The Year by the Des Moines Register, which was a tremendous honor for them. There farm is a little under 400 acres, they have been the driving force behind and the inspiration behind Practical Farmers of Iowa. Dick and Sharon have served as mentors for many, many farm families, not only in Iowa but nationwide. I know Dick and Sharon now have a cow-calf operation, and with their son, Rex, they have some of the facilities we\u27re talking about today, and they\u27re trying some new things in agriculture, so we\u27re pleased to have Dick here

Multi-user investigation organizer

A system that allows a team of geographically dispersed users to collaboratively analyze a mishap event. The system includes a reconfigurable ontology, including instances that are related to and characterize the mishap, a semantic network that receives, indexes and stores, for retrieval, viewing and editing, the instances and links between the instances, a network browser interface for retrieving and viewing screens that present the instances and links to other instances and that allow editing thereof, and a rule-based inference engine, including a collection of rules associated with establishment of links between the instances. A possible conclusion arising from analysis of the mishap event may be characterized as one or more of: not a credible conclusion; an unlikely conclusion; a credible conclusion; conclusion needs analysis; conclusion needs supporting data; conclusion proposed to be closed; and an un-reviewed conclusion

Program findings that inform curriculum development for the prevention of problem gambling

The development of effective problem gambling prevention programs is in its infancy. The present paper discusses results of randomized control trials of two programs that have been implemented in Alberta, Canada. The first is a 10 session program delivered to several classes of university students taking Introductory Statistics. This program focused primarily on teaching the probabilities associated with gambling and included several hands-on demonstrations of typical casino table games. The second is a 5 session program delivered to high school students at several sites in southern Alberta. This program was more comprehensive, containing information and exercises on the nature of gambling and problem gambling, gambling fallacies, gambling odds, decision-making, coping skills, and social problem-solving skills. Data concerning gambling attitudes, gambling fallacies and gambling behaviour at 3 and 6-months post-intervention are presented. The findings of these studies are somewhat counter-intuitive and have important implications for the design of effective prevention programs.Alberta Gaming Research InstituteYe

A perspective on biological x-ray and electron microscopy

Abstract. We consider image contrast for electron microscopy of thick hydrated biological specimens, allowing for the use of phase contrast and energy filtering. This allows us to gain perspective on the relative roles of electron and soft X-ray microscopes. Radiation dose is found to depend strongly on ice thickness, with electrons offering lower dose if the ice thickness is less than about 500 nm, and x rays offering lower dose for thicker ice layers

Monensin Improves the Effectiveness of meso-Dimercaptosuccinate when Used to Treat Lead Intoxication in Rats

Among divalent cations, the ionophore monensin shows high activity and selectivity for the transport of lead ions (Pb(2+)) across phospholipid membranes. When coadministered to rats that were receiving meso-dimercaptosuccinate for treatment of Pb intoxication, monensin significantly increased the amount of Pb removed from femur, brain, and heart. It showed a tendency to increase Pb removal from liver and kidney but had no effect of this type in skeletal muscle. Tissue levels of several physiologic (calcium, cobalt, copper, iron, magnesium, manganese, molybdenum, zinc) and nonphysiologic (arsenic, cadmium, chromium, nickel, strontium) elements were also determined after the application of these compounds. Among the physiologic elements, a number of significant changes were seen, including both rising and falling values. The size of these changes was typically around 20% compared with control values, with the largest examples seen in femur. These changes often tended to reverse those of similar size that had occurred during Pb administration. Among the nonphysiologic elements, which were present in trace amounts, the changes were smaller in number but larger in size. None of these changes appears likely to be significant in terms of toxicity, and there were no signs of overt toxicity under any of the conditions employed. Monensin may act by cotransporting Pb(2+) and OH(–) ions out of cells, in exchange for external sodium ions. The net effect would be to shuttle intracellular Pb(2+) to extracellular dimercaptosuccinic acid thereby enhancing its effectiveness. Thus, monensin may be useful for the treatment of Pb intoxication when applied in combination with hydrophilic Pb(2+) chelators

Toward Human-Carnivore Coexistence: Understanding Tolerance for Tigers in Bangladesh

Fostering local community tolerance for endangered carnivores, such as tigers (Panthera tigris), is a core component of many conservation strategies. Identification of antecedents of tolerance will facilitate the development of effective tolerance-building conservation action and secure local community support for, and involvement in, conservation initiatives. We use a stated preference approach for measuring tolerance, based on the ‘Wildlife Stakeholder Acceptance Capacity’ concept, to explore villagers’ tolerance levels for tigers in the Bangladesh Sundarbans, an area where, at the time of the research, human-tiger conflict was severe. We apply structural equation modeling to test an a priori defined theoretical model of tolerance and identify the experiential and psychological basis of tolerance in this community. Our results indicate that beliefs about tigers and about the perceived current tiger population trend are predictors of tolerance for tigers. Positive beliefs about tigers and a belief that the tiger population is not currently increasing are both associated with greater stated tolerance for the species. Contrary to commonly-held notions, negative experiences with tigers do not directly affect tolerance levels; instead, their effect is mediated by villagers’ beliefs about tigers and risk perceptions concerning human-tiger conflict incidents. These findings highlight a need to explore and understand the socio-psychological factors that encourage tolerance towards endangered species. Our research also demonstrates the applicability of this approach to tolerance research to a wide range of socio-economic and cultural contexts and reveals its capacity to enhance carnivore conservation efforts worldwide