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Metal, preferably divalent copper, cobalt or nickel, phthalocyanine tetraamines are used as curing agents for epoxides. The resulting copolymers have high thermal and chemical resistance and are homogeneous. They are useful as binders for laminates, e.g., graphite cloth laminate.
One of the major deleterious late effects of ionizing radiation is related to the induction of neoplasms. In the present report recent experimental results on neoplastic cell transformation by heavy ions are presented, and possible means to circumvent the carcinogenic effect of space radiation are discussed. Biological effects observed in experiments involving the use of energetic heavy ions accelerated at the Bevalac suggest that many of the biological effects observed in earlier space flight experiments may be due to space radiation, particularly cosmic rays. It is found that the effect of radiation on cell transformation is dose-rate dependent. The frequency of neoplastic transformation for a given dose decreases with a decrease of dose rate of Co-60 gamma rays. It is found that various chemical agents give radiation protection, including DMSO.
The critical cooling rate, Rc, for glass formation of a glass containing 40 mol pct Li2O and 60 mol pct SiO2, doped with small amounts of Pt, Au, P2O5, and TiO2 nucleating agents, has been measured. Rc increases with increasing Pt and Au additions, but Pt has a larger effect than Au. Additions of P2O5 tend to decrease Rc, whereas TiO2 has practically no effect on Rc. The devitrified glass nucleated with Pt contains only crystalline Li2O-SiO2, but all the other devitrified glasses, including the undoped glass, contain both Li2O-SiO2 and Li2O-2SiO2. Analysis shows that Rc increases as the concentration of the Li2O-SiO2 phase in the devitrified glass increases.
On-going work at NASA Langley Research Center in the development and demonstration of a paradigm called behavioral networks as an architecture for intelligent agents is described. This work focuses on the need to identify a methodology for smoothly integrating the characteristics of low-level robotic behavior, including actuation and sensing, with intelligent activities such as planning, scheduling, and learning. This work assumes that all these needs can be met within a single methodology, and attempts to formalize this methodology in a connectionist architecture called behavioral networks. Behavioral networks are networks of task processes arranged in a task decomposition hierarchy. These processes are connected by both command/feedback data flow, and by the forward and reverse propagation of weights which measure the dynamic utility of actions and beliefs.
It has been found that fluorodiepoxides are effective antifoaming agents for epoxy processing when applied at a level as low as 0.1 to 0.2 percent, and there is no adverse effect on the properties of the cured products. The novelty of the fluorodiepoxide is that it is reactive and can copolymerize with a conventional epoxy resin at the same time in the same way in forming an inter-crosslinked polymer network. However, when applied at a high level, compatibility problems may prevail.
Parallel window search is applied to single-agent problems by having different processes simultaneously perform iterations of Iterative-Deepening-A(asterisk) (IDA-asterisk) on the same problem but with different cost thresholds. This approach is limited by the time to perform the goal iteration. To overcome this disadvantage, the authors consider node ordering. They discuss how global node ordering by minimum h among nodes with equal f = g + h values can reduce the time complexity of serial IDA-asterisk by reducing the time to perform the iterations prior to the goal iteration. Finally, the two ideas of parallel window search and node ordering are combined to eliminate the weaknesses of each approach while retaining the strengths. The resulting approach, called simply parallel window search, can be used to find a near-optimal solution quickly, improve the solution until it is optimal, and then finally guarantee optimality, depending on the amount of time available.
A process-oriented control model is described for distributed problem solving. The model coordinates the transfer and manipulation of information across independent networked applications, both intelligent and conventional. The model was implemented using SOCIAL, a set of object-oriented tools for distributing computing. Complex sequences of distributed tasks are specified in terms of high level scripts. Scripts are executed by SOCIAL objects called Manager Agents, which realize an intelligent coordination model that routes individual tasks to suitable server applications across the network. These tools are illustrated in a prototype distributed system for decision support of ground operations for NASA's Space Shuttle fleet.
A description is given of UNICORN, a prototype system developed for the purpose of investigating artificial intelligence (AI) concepts supporting spacecraft autonomy. UNICORN employs thematic reasoning, of the type first described by Rodger Schank of Northwestern University, to allow the context-sensitive control of multiple intelligent agents within a blackboard based environment. In its domain of application, UNICORN demonstrates the ability to reason teleologically with focused knowledge. Also presented are some of the lessons learned as a result of this effort. These lessons apply to any effort wherein system level autonomy is the objective.
Report describes experimental study of rate of generation of ammonia and total amount of ammonia generated by chemical reactions between bonding agents and grains of ammonium perchlorate in solid rocket propellants. Also provides insight into mechanisms of chemical reactions between several types of organic amines with solid ammonium perchlorate.
Straight-chain perfluorooctanesulfonic acid (C8 acid) identified as innocuous and stable wetting agent for use with polytetrafluoroethylene-containing electrodes in liquid-feed direct-oxidation fuel cells suggested for use in vehicles and portable power supplies. C8 acid in small concentrations in aqueous liquid solutions of methanol, trimethoxymethane, dimethoxymethane, and trioxane enables oxidation of these substances by use of commercially available electrodes of type designed originally for use with gases. This function specific to C8 acid molecule and not achieved by other related perfluorolkanesulfonic acids.
Large, complex real-time systems such as space and avionics systems are extremely demanding in their scheduling requirements. The current OS design approaches are quite limited in the capabilities they provide for task scheduling. Typically, they simply implement a particular uniprocessor scheduling strategy and do not provide any special support for network scheduling, overload handling, fault tolerance, distributed processing, etc. Our design of the R-Shell real-time environment fcilitates the implementation of a variety of sophisticated but efficient scheduling strategies, including incorporation of all these capabilities. This is accomplished by the use of scheduling agents which reside in the application run-time environment and are responsible for coordinating the scheduling of the application.
Over the past decade, advances in instrumental design and refinements in the understanding of ion molecule reactions at atmospheric pressure enabled the application of Ion Mobility Spectrometry (IMS) as a simple inexpensive and sensitive analytical method for the detection of organic trace compounds. Positive and negative gas-phase ions for ion mobility spectrometry have been produced by a variety of methods, including photo-ionization, laser multi photon ionization, surface ionization, corona discharge ionization. The most common ion source used in ion mobility spectrometry is a radioactive Ni-63 foil which is favored due to simplicity, stability, convenience, and high selectivity. If reactant ions like (H2O(n)H)(+) or (H2O(n)O2)(-) dominate in the reaction region, nearly all kinds of compounds with a given proton or electron affinity; are ionized. However, the radioactivity of the Ni-63 foil is one disadvantage of this ion source that stimulates the development and application of other ionization techniques. In this paper, we report analyses of old chemical warfare agents and toxic wastes using Bruker RAID ion mobility spectrometers. Due to the modular construction of the measuring cell, the spectrometers can be equipped with different ion sources. The combined use of Ni-63, photo- and corona discharge ionization allows the identification of different classes of chemical compounds and yields in most cases comparable results.
Fluorinated ethers used in place of chlorofluorocarbons and hydrochlorofluorocarbons. Replacement necessary because CFC's and HCFC's found to contribute to depletion of ozone from upper atmosphere, and manufacture and use of them by law phased out in near future. Two fluorinated ethers do not have ozone-depletion potential and used in existing foam-producing equipment, designed to handle liquid blowing agents soluble in chemical ingredients that mixed to make foam. Any polyurethane-based foams and several cellular plastics blown with these fluorinated ethers used in processes as diverse as small batch pours, large sprays, or double-band lamination to make insulation for private homes, commercial buildings, shipping containers, and storage tanks. Fluorinated ethers proved useful as replacements for CFC refrigerants and solvents.
A system for and method of detecting and measuring concentrations of an ultrasonically-reflective microsphere contrast agent involving detecting non-linear sum and difference beat frequencies produced by the microspheres when two impinging signals with non-identical frequencies are combined by mixing. These beat frequencies can be used for a variety of applications such as detecting the presence of and measuring the flow rates of biological fluids and industrial liquids, including determining the concentration level of microspheres in the myocardium.
This report covers the results of investigations directed toward studying the effects of novel aromatic diamine structures on epoxy adhesive properties and includes work done under a modification to the original contract. Three aromatic diamines based on diphenylsulfone and benzophenone were studied as epoxy adhesive curing agents. Previously found differences in adhesive strengths for meta vs para orientation were not found in these series. The use of aluminum and alumina as fillers in a m,m'-methylene dianiline-cured epoxy adhesive was not found to be beneficial to adhesive strength. Alumina filled adhesives had much lower strength than unfilled adhesives. The unfilled m,m'-methylene dianiline-based epoxy adhesive had excellent resistance to moisture relative to a p,p'-methylene dianiline-based adhesive and maintained good strengths up to 250 F. A glass fiber composite based on a m,m'-methylene dianiline-cured epoxy appeared to be equivalent to the p,p'-methylene dianiline-cured epoxy as judged by short beam shear tests.
Ozone (03), is the strongest commercial oxidizing agent for aqueous systems and may be ideal for space station laundering operations. It can be generated electronically from air in situ. It kills virtually all microorganisms, attacks many organics and inorganics, and breaks down stable ring structures of benzene and related oils when coupled with ultra violet radiation. It cleans and disinfects in cold water without the need for detergent. It leaves no residues. Ozone permits up to 90% wash water recycling and it eliminates wash time, water volume, and recycling problems of a detergent rinse. Ozone is self purging and converts spontaneously to oxygen. It can be rapidly purged by well established catalytic and thermal processes. Scaling of an ozone laundering system for space station may have commercial applications in a consumer model for home use.
An autotrophic theory of the origin of metabolism and life has been proposed in which carbon dioxide is reduced by ferrous sulfide and hydrogen sulfide by means of a reversed citric acid cycle, leading to the production of amino acids. Similar processes have been proposed for purine synthesis. Ferrous sulfide is a strong reducing agent in the presence of hydrogen sulfide and can produce hydrogen as well as reduce alkenes, alkynes, and thiols to saturated hydrocarbons and reduce ketones to thiols. However, the reduction of carbon dioxide has not been demonstrated. We show here that no amino acids, purities, or pyrimidines are produced from carbon dioxide with the ferrous sulfide and hydrogen sulfide system. Furthermore, this system does not produce amino acids from carboxylic acids by reductive amination and carboxylation. Thus, the proposed autotrophic theory, using carbon dioxide, ferrous sulfide, and hydrogen sulfide, lacks the robustness needed to be a geological process and is, therefore, unlikely to have played a role In the origin of metabolism or the origin of life.
An autotrophic theory of the origin of metabolism and life has been proposed in which carbon dioxide is reduced by ferrous sulfide and hydrogen sulfide by means of a reversed citric acid cycle, leading to the production of amino acids. Similar processes have been proposed for purine synthesis. Ferrous sulfide is a strong reducing agent in the presence of hydrogen sulfide and can produce hydrogen as well as reduce alkenes, alkynes, and thiols to saturated hydrocarbons and reduce ketones to thiols. However, the reduction of carbon dioxide has not been demonstrated. We show here that no amino acids, purines, or pyrimidines are produced from carbon dioxide with the ferrous sulfide and hydrogen sulfide system. Furthermore, this system does not produce amino acids from carboxylic acids by reductive amination and carboxylation. Thus, the proposed autotrophic theory, using carbon dioxide, ferrous sulfide, and hydrogen sulfide, lacks the robustness needed to be a geological process and is, therefore, unlikely to have played a role in the origin of metabolism or the origin of life.