7,392 research outputs found

    Hydroprocessing and Blending of a Biomass-Based DTG-Gasoline

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    The number of annually registered internal-combustion vehicles still exceeds electric-driven ones in most regions, e.g., Germany. Ambitious goals are disclosed with the European Green Deal, which calls for new technical approaches and greenhouse gas neutral transition technologies. Such bridging technologies are synthetic fuels for the transportation sector, e.g., using the bioliq® process for a CO2-neutral gasoline supply. Fuels must meet the applicable national standards to be used in existing engines. Petrochemical parameters can be variably adapted to their requirements by hydroprocessing. In this work, we considered the upgrading of aromatic-rich DTG gasoline from the bioliq® process. The heavy gasoline was therefore separated from the light one by rectification. We investigated how to selectively modify the petrochemical parameters of the heavy gasoline, especially the boiling characteristics, to make the product suitable as a high-quality blending component. Three commercially available Pt/zeolite catalysts were tested over a wide range of temperature and space velocity. We achieved high gasoline yields, while the content of light end compounds up to a boiling temperature of 150°C could be increased significantly. In contrast to the high naphthenic content of the gasoline, the obtained octane numbers were satisfactory. Especially the Motor Octane Number turned out unexpectedly high and showed a dependency on the isomerization of the naphthenic rings. By blending the upgraded heavy gasoline with the previously separated light gasoline, we could finally show that hydroprocessing is suitable for adjusting petrochemical parameters. The aromatic concentration was 37.5% lower than that in the original raw gasoline, while the boiling characteristics improved significantly. Additionally, the final boiling point was 82°C lower, which is beneficial for the emission behavior

    Phase-field-crystal model for liquid crystals

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    Based on static and dynamical density functional theory, a phase-field-crystal model is derived which involves both the translational density and the orientational degree of ordering as well as a local director field. The model exhibits stable isotropic, nematic, smectic A, columnar, plastic crystalline and orientationally ordered crystalline phases. As far as the dynamics is concerned, the translational density is a conserved order parameter while the orientational ordering is non-conserved. The derived phase-field-crystal model can serve for efficient numerical investigations of various nonequilibrium situations in liquid crystals

    Socio-psychological airplane noise investigation in the districts of three Swiss airports: Zurich, Geneva and Basel

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    The results of noise measurements and calculations are available in the form of noise maps for each of the three areas. To measure the stress due to airplane noise the Noise and Number Index (NNI) was applied. In the vicinities of the airports, 400 households were randomly selected in each of the three noise zones (of 10 NNI intervals each). A total of 3939 questionnaires could be evaluated, one quarter of which came from areas without airplane noise. Concurrently, traffic noise was measured in areas of Basel and expressed in sum total levels L sub 50 and the reaction of 944 persons was elicited by interrogation

    Role of serotonin in the hepato-gastroIntestinal tract: an old molecule for new perspectives

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    Abstract.: Beside its role as a neurotransmitter in the central nervous system, serotonin appears to be a central physiologic mediator of many gastrointestinal (GI) functions and a mediator of the brain-gut connection. By acting directly and via modulation of the enteric nervous system, serotonin has numerous effects on the GI tract. The main gut disturbances in which serotonin is involved are acute chemotherapy-induced nausea and vomiting, carcinoid syndrome and irritable bowel syndrome. Serotonin also has mitogenic properties. Platelet-derived serotonin is involved in liver regeneration after partial hepatectomy. In diseased liver, serotonin may play a crucial role in the progression of hepatic fibrosis and the pathogenesis of steatohepatitis. Better understanding of the role of the serotonin receptor subtypes and serotonin mechanisms of action in the liver and gut may open new therapeutic strategies in hepato-gastrointestinal disease

    On the Geometry of Supersymmetric Quantum Mechanical Systems

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    We consider some simple examples of supersymmetric quantum mechanical systems and explore their possible geometric interpretation with the help of geometric aspects of real Clifford algebras. This leads to natural extensions of the considered systems to higher dimensions and more complicated potentials.Comment: 18 page

    Strong correlation effects and optical conductivity in electron doped cuprates

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    We demonstrate that most features ascribed to strong correlation effects in various spectroscopies of the cuprates are captured by a calculation of the self-energy incorporating effects of spin and charge fluctuations. The self energy is calculated over the full doping range of electron-doped cuprates from half filling to the overdoped system. The spectral function reveals four subbands, two widely split incoherent bands representing the remnant of the split Hubbard bands, and two additional coherent, spin- and charge-dressed in-gap bands split by a spin-density wave, which collapses in the overdoped regime. The incoherent features persist to high doping, producing a remnant Mott gap in the optical spectra, while transitions between the in-gap states lead to pseudogap features in the mid-infrared.Comment: 5 pages, 4 figure

    Multiband effects on beta-FeSe single crystals

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    We present the upper critical fields Hc2(T) and Hall effect in beta-FeSe single crystals. The Hc2(T) increases as the temperature is lowered for field applied parallel and perpendicular to (101), the natural growth facet of the crystal. The Hc2(T) for both field directions and the anisotropy at low temperature increase under pressure. Hole carriers are dominant at high magnetic fields. However, the contribution of electron-type carriers is significant at low fields and low temperature. Our results show that multiband effects dominate Hc2(T) and electronic transport in the normal state

    Identification of the Orbital Pairing Symmetry in UPt_3

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    This paper summarizes the results of a comprehensive analysis of the thermodynamic and transport data for the superconducting phases of UPt_3. Calculations of the transverse sound attenuation as a function of temperature, frequency, polarization, and disorder are presented for the leading models of the superconducting order parameter. Measurements of the specific heat, thermal conductivity, and transverse sound attenuation place strong constraints on the orbital symmetry of the superconducting order parameter. We show that the superconducting A and B phases are in excellent agreement with pairing states belonging to the odd-parity E_{2u} orbital representation.Comment: 11 pages with 7 figure

    Sulphur-bearing molecules in diffuse molecular clouds: new results from SOFIA/GREAT and the IRAM 30 m telescope

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    We have observed five sulphur-bearing molecules in foreground diffuse molecular clouds lying along the sight-lines to five bright continuum sources. We have used the GREAT instrument on SOFIA to observe the 1383 GHz 2Π3/2J=5/2−3/2^2\Pi_{3/2} J=5/2-3/2 transitions of SH towards the star-forming regions W31C, G29.96-0.02, G34.3+0.1, W49N and W51, detecting foreground absorption towards all five sources; and the EMIR receivers on the IRAM 30m telescope at Pico Veleta to detect the H2_2S 1(10)-1(01), CS J=2-1 and SO 3(2)-2(1) transitions. In nine foreground absorption components detected towards these sources, the inferred column densities of the four detected molecules showed relatively constant ratios, with N(SH)/N(H2_2S) in the range 1.1 - 3.0, N(CS)/N(H2_2S) in the range 0.32 - 0.61, and N(SO)/N(H2_2S) in the range 0.08 - 0.30. The observed SH/H2_2 ratios - in the range (0.5-2.6) ×10−8\times 10^{-8} - indicate that SH (and other sulphur-bearing molecules) account for << 1% of the gas-phase sulphur nuclei. The observed abundances of sulphur-bearing molecules, however, greatly exceed those predicted by standard models of cold diffuse molecular clouds, providing further evidence for the enhancement of endothermic reaction rates by elevated temperatures or ion-neutral drift. We have considered the observed abundance ratios in the context of shock and turbulent dissipation region (TDR) models. Using the TDR model, we find that the turbulent energy available at large scale in the diffuse ISM is sufficient to explain the observed column densities of SH and CS. Standard shock and TDR models, however, fail to reproduce the column densities of H2_2S and SO by a factor of about 10; more elaborate shock models - in which account is taken of the velocity drift, relative to H2_2, of SH molecules produced by the dissociative recombination of H3_3S+^+ - reduce this discrepancy to a factor ~ 3.Comment: 30 pages, accepted for publication in A&
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