Laboratory studies of some of the major ion-molecule reactions occurring in cometary comae

1980 ◽  
Vol 44 ◽  
pp. 481 ◽  
Author(s):  
W. T., Jr. Huntress ◽  
V. G. Anicich ◽  
M. J. McEwan ◽  
Z. Karpas
Keyword(s):  
Laboratory Studies ◽  
Major Ion ◽  
Ion Molecule Reactions ◽  
Cometary Comae

Laboratory studies of isotope exchange in ion-neutral reactions: interstellar implications

1981 ◽  
Vol 303 (1480) ◽  
pp. 535-542 ◽  
Keyword(s):  
Low Temperatures ◽  
Isotope Exchange ◽  
Laboratory Data ◽  
Isotopic Ratios ◽  
Laboratory Studies ◽  
Terrestrial Environment ◽  
Interstellar Clouds ◽  
Ion Molecule Reactions ◽  
Significant Process ◽  
Molecule Interactions

The rare stable isotopes of several elements (e.g. D, 13 C and 15 N) have been detected in several interstellar molecules, and their abundance relative to the more common isotope is often enhanced above that in the solar-terrestrial environment. Important questions to answer are to what extent the isotopic ratios in the molecules are representative of those in the cloud matter as a whole, and whether fractionation of the heavier isotope into the molecules via ion—molecule interactions is a significant process. A laboratory study of isotope exchange in ion-molecule reactions has therefore been carried out, the results of which indicate that fractionation of heavy isotopes can occur very efficiently at low temperatures. Consideration is given in this paper to reactions in which H-D, 12 C - 13 C, 14 N - 15 N and 16 O - 18 O exchange occurs, and it is shown how better estimates of the electron density and the temperature in interstellar clouds have been obtained from these laboratory data.

scholarly journals Laboratory Studies of Interstellar Carbon/Nitrogen Ion Chemistry

1980 ◽  
Vol 87 ◽  
pp. 307-310
Author(s):  
H. I. Schiff ◽  
G. I. Mackay ◽  
G. D. Vlachos ◽  
D. K. Bohme
Keyword(s):  
Bond Formation ◽  
Laboratory Studies ◽  
Laboratory Measurements ◽  
Ion Chemistry ◽  
Loss Process ◽  
Ion Molecule Reactions ◽  
Radiative Association ◽  
Major Loss ◽  
Nitrogen Ion ◽  
N Compounds

Laboratory measurements are reported for ion-molecule reactions involving CN+, HCN+, C2N+ and HCN, and their implications for interstellar synthesis for C/N compounds are discussed. The reaction of C+ with HCN was found not to constitute a major loss process for HCN, which is regenerated by reactions of C2N+ with NH3, H20, CH4, C2H2 and H2S. These latter reactions lead to C addition rather than C-N bond formation. Rapid association reactions were observed for CH3+ and C2H2+ with HCN. These suggest efficient radiative association reactions under interstellar conditions to form ions which may form larger C/N compounds upon neutralization.

Hydrogen Cyanide Polymers from the Impact of Comet P/Shoemaker-Levy 9 on Jupiter

1997 ◽  
Vol 161 ◽  
pp. 179-187
Author(s):  
Clifford N. Matthews ◽  
Rose A. Pesce-Rodriguez ◽  
Shirley A. Liebman
Keyword(s):  
Amino Acids ◽  
Solar System ◽  
Hydrogen Cyanide ◽  
Nitrogen Heterocycles ◽  
Laboratory Studies ◽  
Heterogeneous Solids ◽  
The Many ◽  
Comet Halley ◽  
The Impact ◽  
By Products

AbstractHydrogen cyanide polymers – heterogeneous solids ranging in color from yellow to orange to brown to black – may be among the organic macromolecules most readily formed within the Solar System. The non-volatile black crust of comet Halley, for example, as well as the extensive orangebrown streaks in the atmosphere of Jupiter, might consist largely of such polymers synthesized from HCN formed by photolysis of methane and ammonia, the color observed depending on the concentration of HCN involved. Laboratory studies of these ubiquitous compounds point to the presence of polyamidine structures synthesized directly from hydrogen cyanide. These would be converted by water to polypeptides which can be further hydrolyzed to α-amino acids. Black polymers and multimers with conjugated ladder structures derived from HCN could also be formed and might well be the source of the many nitrogen heterocycles, adenine included, observed after pyrolysis. The dark brown color arising from the impacts of comet P/Shoemaker-Levy 9 on Jupiter might therefore be mainly caused by the presence of HCN polymers, whether originally present, deposited by the impactor or synthesized directly from HCN. Spectroscopic detection of these predicted macromolecules and their hydrolytic and pyrolytic by-products would strengthen significantly the hypothesis that cyanide polymerization is a preferred pathway for prebiotic and extraterrestrial chemistry.

Cognitive Aging in a Precision Sport Context

1996 ◽  
Vol 1 (3) ◽  
pp. 166-179 ◽  
Author(s):  
Bo Molander ◽  
Lars Bäckman
Keyword(s):  
Older Adult ◽  
Cognitive Abilities ◽  
Cognitive Aging ◽  
Motor Performance ◽  
Intervention Programs ◽  
Laboratory Studies ◽  
High Arousal ◽  
Memory And Attention ◽  
Age Related ◽  
Principal Finding

Highly skilled miniature golf players were examined in a series of field and laboratory studies. The principal finding from these studies is that young and young adult players (range = 15-38 years) score equally well or better in competition than in training whereas older adult players (range = 46-73 years) perform worse in competitive events than under training conditions. It was also found that the impairment in motor performance on the part of the older players is associated with age-related deficits in basic cognitive abilities, such as memory and attention. These results support the hypothesis that older players may be able to compensate for age-related deficits under relaxed conditions, but not under conditions of high arousal. The possibility of improving the performance of the older players in stressful situations by means of various intervention programs is discussed.

Automation Surprise

2017 ◽  
Vol 7 (1) ◽  
pp. 28-41 ◽  
Author(s):  
Robert J. de Boer ◽  
Karel Hurts
Keyword(s):  
Flight Control ◽  
Representative Sample ◽  
Aviation Safety ◽  
Control Mode ◽  
Cognitive Errors ◽  
Laboratory Studies ◽  
Airline Pilots ◽  
Flight Operations ◽  
Widespread Phenomenon ◽  
Few Data

Abstract. Automation surprise (AS) has often been associated with aviation safety incidents. Although numerous laboratory studies have been conducted, few data are available from routine flight operations. A survey among a representative sample of 200 Dutch airline pilots was used to determine the prevalence of AS and the severity of its consequences, and to test some of the factors leading to AS. Results show that AS is a relatively widespread phenomenon that occurs three times per year per pilot on average but rarely has serious consequences. In less than 10% of the AS cases that were reviewed, an undesired aircraft state was induced. Reportable occurrences are estimated to occur only once every 1–3 years per pilot. Factors leading to a higher prevalence of AS include less flying experience, increasing complexity of the flight control mode, and flight duty periods of over 8 hr. It is concluded that AS is a manifestation of system and interface complexity rather than cognitive errors.

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