159 research outputs found
Acrylic acid (CH <inf>2</inf>CHCOOH): The rotational spectrum in the millimetre range up to 397 GHz
No full textIn order to facilitate its detection in astronomical observations, the measurement of the rotational spectrum of acrylic acid has been extended to 397 GHz using a free space cell at room temperature. 295 new lines were assigned to the s-cis conformer and 286 new lines to the s-trans conformer of acrylic acid. Using the determined experimental parameters, the predictions of the rotational transition frequencies up to 900 GHz and their intensities were obtained at temperatures of 100 and 200 K and at room temperature. Based on these predictions, a search of the most intense transitions of acrylic acid in star-forming regions was performed using published data from the HERSCHEL Science Archive. No lines were found but the possibility of observing rotational transitions of acrylic acid in astronomical objects is discussed
Millimeter Wave Spectrum of the Weakly Bound Complex CH2=CHCN·H2O: Structure, Dynamics, and Implications for Astronomical Search
No full textThe weakly bound 1:1 complex between acrylonitrile (CH2=CHCN) and water has been characterized spectroscopically in the millimeter wave range (59.6-74.4 GHz) using a Free Jet Absorption Millimeter Wave spectrometer. Precise values of the rotational and quartic centrifugal distortion constants have been obtained from the measured frequencies of the normal and isotopically substituted water moiety (DOH, DOD, H18OH). Structural parameters have been estimated from the rotational constants and their differences among isotopologues: the complex has a planar structure with the two subunits held together by a O-H···N (2.331(3) Å) and a C-H···O (2.508(4) Å) interaction. The ab initio intermolecular binding energy, obtained at the counterpoise corrected MP2/aug-cc-pVTZ level of calculation, is De = 24.4 kJ mol-
An Architectural Support for Self-Adaptive Software for Treating Faults
No full textConsidering the current trend of building systems from existing components that allow neither code inspection nor change, the solution for enabling dynamic adaptation of software systems should not be intrusive in the way that components should be designed. The architectural approach for treating faults described in this paper, instead of providing mechanisms and techniques at the component level, it relies on the interactions between components for obtaining flexible software structures that are nevertheless robust to the occurrence of undesirable events
"Perfect perfect"
No full text"Perfect perfect" : d. kodierte Kind in Werbung u. Kurzgeschichte (Katherine Mansfield, Marie-Luise Kaschnitz, Gabriele Wohmann, Christa Wolf u.a.) : Vortr. gehalten anläßl. d. Augsburger Mansfield-Symposiums im Juni 1988 zum 100. Geburtstag von Katherine Mansfield. - Augsburg, 1989. - 32, [7] S. - (Augsburger Universitätsreden ; 15
Combined crossed beam and theoretical studies of the N(2D)+C2H4 reaction and implications for atmospheric models of Titan
No full textThe dynamics of the H-displacement channels in the reaction N(2D) + C2H4 have been investigated by the crossed molecular beam technique with mass spectrometric detection and time-of-flight analysis at two different collision energies (17.2 and 28.2 kJ/mol). The interpretation of the scattering results is assisted by new electronic structure calculations of stationary points and product energetics for the C2H4N ground state doublet potential energy surface. RRKM statistical calculations have been performed to derive the product branching ratio under the conditions of the present experiments and of the atmosphere of Titan. Similarities and differences with respect to a recent study performed in cross beam experiments coupled to ionization via tunable VUV synchrotron radiation are discussed [Lee, S.-H. et al., Phys. Chem. Chem. Phys. 2011, 13, 8515]. Implications for the atmospheric chemistry of Titan are presented
Experimental and theoretical investigations of the ion-neutral reaction of C<sub>2</sub>H<sub>2</sub>N<sup>+</sup> with C<sub>2</sub>H<sub>6</sub> and implications on chain elongation processes in Titan's atmosphere
No full textIn this study we report theoretical and experimental evidence for the formation of ionic products by the ion-neutral reaction of C2H2N+ with C2H6. Our investigations consist of laboratory measurements using a guided ion beam mass spectrometer together with complementary ab initio quantum chemical computations, at the MP2/6-311++G(d,p) level of theory, in order to elucidate the energetics and geometries of the intermediates and transition states that are involved in the production of the observed product ions. This study also provides insights on the isomeric nature of the observed product ions, their formation pathways together with collision energy and pressure dependences. The experimental data agrees well with the predictions of the ab initio calculations. Despite data provides evidence for the occurrence of C2H5+ as the most salient product ion, the production of CH3+, C2H3+, C3H5+, C3H7+ and C2H4N+ is also evident. A reaction scheme was proposed to elucidate the mechanisms responsible for the formation of the observed product ions. These processes might be intermediate steps in the generation of long chain carbon and nitrogen-bearing compounds in Titan's ionosphere, the interstellar medium or circumstellar envelopes.</p
Dissociative recombination of organic molecular ions of relevance for interstellar clouds and Titan's upper atmosphere [Elektronisk resurs]
No full textThis thesis presents experimental studies on the dissociative recombination (DR) of the organic molecular ions CD3CND+, CH2CHCNH+, CH3CH2CNH+, CD3CDO+, CH3CHO+ and DCOOD2+. The experiments were all performed at the heavy ion storage ring CRYRING at the Manne Siegbahn Laboratory in Stockholm, Sweden. DR is the process in which a singly charged molecular cation captures a free electron, forming a highly excited intermediate molecule which then dissociates into exclusively neutral fragments. The process plays an important role as a plasma neutralizing mechanism in many cold, low density plasmas such as those encountered in planetary ionospheres and interstellar clouds. DR can also act as the final step in the gas-phase synthesis of different neutral molecules in such environments. Our experimental findings indicate that nitriles that are lost by protonation in Titan’s upper atmosphere or in interstellar clouds to a large extent may be recycled by DR. Also, it appears that the DR of nitrile ions does not break the C-N bond, which supports the hypothesis that nitriles which are formed in Titan’s upper atmosphere do not degrade to recover N2. For the studied acetaldehyde cations, CD3CDO+ and CH3CHO+, we observed a considerable isotopic effect in the cross section, with the lighter isotopologue being more reactive. In the DR of DCOOD2+ an upper limit of only 13% for the branching fraction of the DCOOD + D channel was found. This finding has pronounced effects on the predicted abundance of formic acid in dark clouds.</p
Record documentation of AFTO 781 series in the aspect of safety of operation of F-16 aircraft at Poznan - Krzesiny airport. Analysis of experience in 2010 - 2020
No full textThe purpose of the article is to present the conclusions and discuss the results of research outcome from the implementation and use of AFTO 781 record documentation in the formation of safety in the process of operation of a multirole aircraft F-16 C/D Block 52+ at Poznan - Krzesiny Airport in 2010 - 2020. Methods: Surveying and analyzing archival documents for comparison in the context of verifying the reliability of data. Results: The result of the conducted research is the presentation of research results and conclusions resulting from several years of use of AFTO 781 record documentation in the process of operation of F-16 C/D Block 52+ multirole aircraft at Poznan - Krzesiny Airport in 2010 - 2020. Conclusions: The main objective of the conducted study was to define the factors determining the functionality of the AFTO 781 series record documentation, in the process of maintaining a certain level of safety in the operation of F-16 aircraft. In addition, the analysis of the results of the study allowed the author to interpret the ability of technical personnel to use the functionality of the AFTO 781 series record documentation in question, as well as to define the following conclusions and proposals for action, in order to minimize the occurrence of potential risks in the operation of aircraft equipment in the future
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