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Temperature limit of 25-conductor signal cable and 3-conductor power cable, fabricated using woven and roll laminated technique, increased from 200 C to 350 C when polyimide/fluorinated ethylene propylene or polytetrafluoroethylene insulation films and fluorinated ethylene propylene as adhesive medium is applied.
Membranes are synthesized from ethylene and nitrogen in RF plasma at low power, gas-flow rates, and pressure. Ethylene and nitrogen are used because flow rate and partial pressure of each gas can be independently controlled to produce optimum conditions for synthesizing membrane. Membrane is particularly useful in recycling and purifying water.
Nitric oxide, ozone, and ethylene were monitored over roads during periods of heavy traffic by transmitting several known laser wavelengths over an atmospheric path and measuring the differential absorption of the wavelengths. Heavy afternoon traffic between four and five o'clock over a 3.75 km path produced a noticeable increase in ethylene and a decrease in ozone. The changes occurred on a short time scale and correlated with the sudden traffic density increase. The ozone decrease occurs because of the sudden presence of large quantities of nitric oxide. Although the laboratory laser equipment used is rather cumbersome, the measurements did point out the potential of the laser absorption technique for monitoring large areas from one location.-
Compositions of polypropylene and ethylene-acrylic acid resins filled with high levels of alumina trihydrate of magnesium hydroxide were examined for smoke generation and impact resistance. Best results were obtained using alumina trihydrate coated with a low modulus elastomer, and ethylene-acrylic acid resin. Addition of polyvinyl alcohol fibers to the filled resin improves impact resistance and causes somewhat of an increase in smoke evolution.
The development of a low cost and reliable contact system for solar cells and the fabrication of several solar cell modules using ultrasonic bonding for the interconnection of cells and ethylene vinyl acetate as the potting material for module encapsulation are examined. The cells in the modules were made from dendritic web silicon. To reduce cost, the electroplated layer of silver was replaced with an electroplated layer of copper. The modules that were fabricated used the evaporated Ti, Pd, Ag and electroplated Cu (TiPdAg/Cu) system. Adherence of Ni to Si is improved if a nickel silicide can be formed by heat treatment. The effectiveness of Ni as a diffusion barrier to Cu and the ease with which nickel silicide is formed is discussed. The fabrication of three modules using dendritic web silicon and employing ultrasonic bonding for interconnecting calls and ethylene vinyl acetate as the potting material is examined.
It is known that the addition of phosphate buffer to two polymer aqueous phase systems has a strong effect on the partition behavior of cells and other particles in such mixtures. The addition of sodium phosphate to aqueous poly(ethylene glycol) dextran phase systems causes a concentration-dependent shift in binodial on the phase diagram, progressively lowering the critical conditions for phase separation as the phosphate concentration is increased. Sodium chloride produces no significant shift in the critical point relative to the salt-free case. Accurate determinations of the phase diagram require measurements of the density of the phases; data is presented which allows this parameter to be calculated from polarimetric measurements of the dextran concentrations of both phases. Increasing polymer concentrations in the phase systems produce increasing preference of the phosphate for the dextran-rich bottom phase. Equilibrium dialysis experiments showed that poly(ethylene glycol) effectively rejected phosphate, and to a lesser extent chloride, but that dextran had little effect on the distribution of either salt. Increasing ionic strength via addition of 0.15 M NaCl to phase systems containing 0.01 M phosphate produces an increased concentration of phosphate ions in the bottom dextran-rich phase, the expected effect in this type of Donnan distribution.
Alloy tubes filled with hydrogen doped with various amounts of carbon monoxide, carbon dioxide, ethane, ethylene, methane, ammonia, or water were heated in a diesel fuel-fired Stirling engine simulator materials test rig for 100 hours at 21 MPa and 760 or 820 C to determine the effectiveness of the dopants in reducing hydrogen permeation through the hot tube walls. Ultra high purity (UHP) hydrogen was used for comparison. The tube alloys were N-155, A-286, Incoloy 800, Nitronic 40, 19-9DL, 316 stainless steel, Inconel 718, and HS-188. Carbon dioxide and carbon monoxide in the concentration range 0.2 to 5 vol % were most effective in reducing hydrogen permeation through the hot tube walls for all alloys. Ethane, ethylene, methane, ammonia, and water at the concentrations investigated were not effective in reducing the permeation below that achieved with UHP hydrogen. One series of tests were conducted with UHP hydrogen in carburized tubes. Carburization of the tubes prior to exposure reduced permeation to values similar to those for carbon monoxide; however, carbon dioxide was the most effective dopant.
The curvatures produced in leaf blades by auxin treatment have been described as nastic curvatures because the initial differential growth is always enhanced on the lower side, regardless of the side of application. It is now known, however, that blades can show differential growth of either the upper or the lower side depending on the conditions of treatment. The dorsiventrality of the blade therefore influences but does not limit the direction of curvature. The dorsiventral directionality of response to growth regulators and the response to changes in the orientation to gravity are seen as indicating that blade curvatures are analogous to negative or positive gravitropism. It is noted that neither blade hyponasty or epinasty can be accounted for by ethylene alone. Petiole responses, however, are not directional, and the leaf angle changes induced by rotation or auxin treatment can be accounted for by ethylene production.
One problem encountered in the use of air-quality instrumentation on aircraft is the variation of instrument sensitivity with pressure as the result of altitude changes of the aircraft. Many instruments experience sensitivity changes of as much as a factor of 2 at altitudes of 6 km. Discussed are recent modifications to a chemiluminescent (ethylene) ozone detector that allow the instrument to automatically compensate for pressure/sensitivity effects. The modification provides automated mass flow rate control for both the sample and ethylene gas flows. The flow control systems maintain flow rate to within 15 percent for a 100-torr instantaneous pressure change, and flow rates are returned to the desired set points within 10 s after the pressure change. During simulated altitude changes (300 m/min from mean sea level to 3-km altitude), flow rates were controlled to within 3 percent of the set point. Laboratory data are summarized verifying the operation of the instrument for a pressure range of 760 torr (sea level) to 350 torr (approximately 20,000 ft) and an ozone concentration range from 20 to approximately 700 ppb.
In the past year we have gained useful information on several aspects of leaf blade growth. The most important observations are as follows: The C(14)-1AA moves preferentially in a gravipositive dorsiventral direction through the blade. This movement is inhibited by inversion of the blade. The responding cells in leaf blade hyponasty are in the lower epidermis and bundle sheath cells. Two additional responses in the leaf were characterized. In addition to blade curvature, the leaf shows petiole curvature and changes in the liminal angle subtended by the pulvinus. Ethylene production was studied under a number of conditions. The blade, rather than the petiole or pulvinus, is the principal site of auxin-promoted ethylene synthesis. The effects of a variety of agents on the blade, including gibberellic acid, abscisic acid, vanadate, low pH buffers, and blue light were reviewed.
The objective of the work reported herein was to explore the use of a continuous operation plasma torch as an ignitor and flameholder for scramjet combustion. This research was motivated by the desire to eliminate the use of pyrophoric or toxic ignition and/or combustion enhancement materials in operational aircraft or shipboard systems. The total temperatures and torch powers used to ignite/flamehold Mach 2 combustion with hydrogen, ethylene, ethane, and methane were determined. The minimum ignition total temperatures for the fuels tested were hydrogen - 1065 R (lowest test temperature); ethylene - 1500 R; ethane - 2000 R; methane - 2700 R. These temperatures were obtained while operating the torch at a nominal 2 kw net power. The torch was shown to be a good ignitor and flameholder in that both hydrogen and hydrocarbon fuels could be stabilized by the torch and would 'blow off' when the torch was extinguished. The effectiveness of the torch was very sensitive to relative fuel injection location. Best combustion resulted when fuel was injected both upstream and downstream of the torch. These results indicated that an adiabatic plasma torch operating at about 2 kw could be an effective ignitor and flameholder for high-speed combustion.
The experiments designed to document cell-wall level changes which occur as a result of their gravistimulation are described. The goal of this research is to elucidate the mechanism and time frame of differential growth following a controlled gravistimulation. To achieve this, rates of wall deposition will be determined by following the incorporation of radioactive monosaccharides into the wall. Complementing this experiment will be a freeze-etch study directed at revealing the spatial arrangment of both newly-deposited microfibrils and microfibrils that were present in the growing root prior to stimulation. The second phase of the proposed research will examine the roles ethylene and Ca(2+) have in the modulation of differential wall changes during gravitropism. Ethylene and Ca(2+) have both been implicated as regulators of the gravitropic response in roots and they have also been implicated as regulators of the gravitropic response in roots and they have also been reported to exert some control on the orientation of microfibrils. Both of these agents will be manipulated in such a way as to reveal whether they have a direct influence on cell wall deposition and microfibrillar alignment during the geotropic response.
Several generations of Arabidopsis thaliana were grown axenically from seed to seed on nutrient agar medium. The Arabidopsis plants produce seeds within 30 days after seeding, when grown either in containers open to the ambient atmosphere or in large sealed jars, but not in sealed test tubes. Moreover, the plant height was directly proportional to the size of the sealed container. Periodic analyses of the CO2 levels in the sealed containers has shown a decrease during the first week, but a tenfold increase in the following weeks. It is speculated that, by the end of the second week, the cotyledons entering the senescence stage would release ethylene into the culture atmosphere with a concomitant release of CO2, which in turn would induce further release of ethylene, hastening the senescence process in other tissues. Thus, in a controlled ecological life-support system of a space station, various components of the plant atmosphere may have to be maintained within the prescribed limits.
Soot formation in pyrolysis of chlorinated methanes, their mixtures with methane, and chlorinated ethylenes were studied behind reflected shock waves by monitoring the attenuation of an He-Ne laser beam. An additional single-pulse shock-tube study was conducted for the pyrolysis of methane, methyl chloride, and dichloromethane. The experiments were performed at temperatures 1300-3000 K, pressures of 0.4-3.6 bar, and total carbon atom concentrations of 1-5 x 10 to the 17th atoms cu cm. The amounts of soot produced in the pyrolysis of chlorinated hydrocarbons are larger than that of their nonchlorinated counterparts. The sooting behavior and product distribution can be generally explained in terms of chlorine-catalyzed chemical reaction mechanisms. The pathway to soot from chlorinated methanes and ethylenes with high H:Cl ratio proceeds via the formation of C2H, C2H2, and C2H3 species. For chlorinated hydrocarbons with low H:Cl ratio, the formation of C2 and its contribution to soot formation at high temperatures becomes significant. There is evidence for the importance of CHCl radical and its reactions in the pyrolysis of dichloromethane.
It is reported that the interface between plastic film back covers and ethylene vinyl acetates (EVA) or polyvinyl butyral (PVB) in photovoltaic modules can influence water permeation, and electrial properties of the composites such as leakage current and dielectric constant. The interface can either be one of two dissimilar materials in physical contact with no intermixing, or the interface can constitute a thin zone which is an interphase of the two materials having a gradient composition from one material to the other. The former condition is described as a discrete interface. A discrete interface model was developed to predict water permeation, dielectric strength, and leakage current for EVA, ethylene methyl acrylate (EMA), and PVB coupled to Tedlar and mylar films. Experimental data was compared with predicted data.
Poly(ethylene glycol) film controls electrostatic potential. Electro-osmosis in quartz or glass chambers reduced or reversed by coating inside surface of chambers with monomacromolecular layers of poly(ethylene glycol). Stable over long times. Electrostatic potential across surface of untreated glass or plastic chamber used in electro-phoresis is negative and attracts cations in aqueous electrolyte. Cations solvated, entrains flow of electrolyte migrating toward cathode. Electro-osmotic flow interferes with desired electrophoresis of particles suspended in electrolyte. Polymer coats nontoxic, transparent, and neutral, advantageous for use in electrophoresis.
Experimental measurements have been obtained for the chemical yields of hydrogen cyanide, acetylene, ethylene, ethane, and propane from simulated lightning discharges, in order to ascertain whether lightning in the troposphere of Titan may be contributing to the hydrocarbon inventory. A comparison of these results with those obtained on the basis of thermodynamic equilibrium considerations shows substantial discrepancies and implies that thermodynamic equilibrium theories are inadequate. The production of ethylene by lightning and its subsequent stratospheric diffusion nevertheless appears to be one reasonable mechanism.
The Biomass Production Chamber at Kennedy Space Center was constructed to conduct large scale plant growth studies for NASA's CELSS program. Over the past four years, physical systems and computer control software have been continually upgraded and the degree of atmospheric leakage from the chamber has decreased from about 40 to 5 percent of the total volume per day. Early tests conducted with a limited degree of closure showed that total crop (wheat) growth from the best trays was within 80 percent of reported optimal yields for similar light levels. Yields from subsequent tests under more tightly closed conditions have not been as good--up to only 65 percent of optimal yields. Yields appear to have decreased with increasing closure, yet potential problems exist in cultural techniques and further studies are warranted. With the ability to tightly seal the chamber, quantitative data were gathered on CO2 and water exchange rates. Results showed that stand photosynthesis and transpiration reached a peak near 25 days after planting, soon after full vegetative ground cover was established. In the final phase of testing when atmospheric closure was the highest, ethylene gas levels in the chamber rose from about 10 to nearly 120 ppb. Evidence suggests that the ethylene originated from the wheat plants themselves and may have caused an epinastic rolling of the leaves, but no apparent detrimental effects on whole plant function.