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| 2. |
- Fischer, G., et al.
(författare)
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Calibration of the JUICE RWI Antennas by Numerical Simulation
- 2021
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Ingår i: Radio Science. - : American Geophysical Union (AGU). - 0048-6604 .- 1944-799X. ; 56:11
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Tidskriftsartikel (refereegranskat)abstract
- The reception properties of the Radio Wave Instrument (RWI) onboard JUICE (Jupiter Icy Moons Explorer) have been determined using numerical methods applied to a mesh-grid model of the spacecraft. The RWI is part of the RPWI (Radio and Plasma Wave Investigation) and consists of three perpendicular dipoles mounted on a long boom. We determined their effective lengths vectors and capacitive impedances of 8-9 pF. We also investigated the change in effective antenna angles as a function of solar panel rotation and calculated the directivity of the antennas at higher frequencies up to the maximum frequency of 45 MHz of the receiver. We found that the RWI dipoles can be used for direction-finding with an accuracy of 2 degrees up to a frequency of 1.5 MHz. Additionally we calculated the influence of strong pulses from the JUICE active radar on RPWI and found that they should do no harm to its sensors and receivers.
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| 3. |
- Brown, P., et al.
(författare)
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Meeting the Magnetic Emc Challenges for the In-Situ Field Measurements on the Juice Mission
- 2019
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Ingår i: Proceedings of 2019 ESA Workshop on Aerospace EMC (Aerospace EMC). - : IEEE. - 9789082684780
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Konferensbidrag (refereegranskat)abstract
- The JUICE (JUpiter ICy moon Explorer) mission features instrument designs tailored to meet the specific challenges of the respective measuring environment, including EMC constraints. We describe the magnetic field science requirements for this mission and show how they drive the EMC requirements on the spacecraft and selected in-situ instrument configurations. We describe the results of two mutual interference campaigns and discuss the design mitigations employed in order to realise in-situ magnetic and electric field data in-flight with the accuracy required to meet very challenging mission science goals.
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| 4. |
- Bergman, Jan, et al.
(författare)
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DARTS - Distributed Aperture Radio Telescope in Space - First Starlight Explorer
- 2018
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Ingår i: 2018 2nd URSI Atlantic Radio Science Meeting, AT-RASC 2018. - : IEEE. - 9789082598735
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Konferensbidrag (refereegranskat)abstract
- SBERGMANURSIATDARTS1. However, despite the strong science case for the opening up of a brand-new window on the Universe at a low radio frequency that is largely unexplored, mission proposals have been significantly challenged with the lack of flight proven technologies, to implement a space telescope using low cost small spacecraft formations. In recent years, the advent of CubeSat technologies, interplanetary missions and radio frequency inter-satellite link (ISL) technology, have improved to the point that developing a mission where a space radio telescope is formed using a constellation of small satellites is now viable, to bring unique science offerings.
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| 5. |
- Berg, Robert, et al.
(författare)
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Synthesis of thieno[2,3-b]indole-2,3-diones and their ring expansions induced by diazomethane
- 2017
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Ingår i: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 73:38, s. 5654-5658
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Tidskriftsartikel (refereegranskat)abstract
- Indole-2-thione 3 reacted quickly with oxalyl chloride to yield thieno[2,3-b]indole-2,3-dione 4 together with the isomer thiazolo[3,2-a]indole-2,3-dione 5. These thieno[2,3-b]indole-2,3diones underwent ring expansions when treated with diazomethane and e.g. thieno[2,3-b]indole-2,3-dione 4 gave the thiopyrano derivative 16, after two insertions.
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| 6. |
- Koch, Daniel, et al.
(författare)
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2,2 '-Biindolyl Reactions with Aldehydes
- 2016
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Ingår i: European Journal of Organic Chemistry. - : Wiley-VCH Verlag. - 1434-193X .- 1099-0690. ; :7, s. 1389-1396
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Tidskriftsartikel (refereegranskat)abstract
- 2,2'-Biindolyl has been condensed with aromatic and aliphatic aldehydes and products featuring 10-membered rings have been obtained. Thus, benzaldehyde gave compound 24a as the primary product, which readily underwent transannular oxidative coupling to 25a. The structures of both compounds were confirmed by X-ray crystallography. The product from 2,2'-biindolyl and formaldehyde under strongly acidic conditions was slightly different leading to compound 11, whose structure also was confirmed by X-ray crystallography. In this case, two molecules of 2,2'-biindolyl reacted with six molecules of formaldehyde.
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| 7. |
- Smirnova, Anna, et al.
(författare)
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Evidence for New Light-Independent Pathways for Generation of the Endogenous Aryl Hydrocarbon Receptor Agonist FICZ
- 2016
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Ingår i: Chemical Research in Toxicology. - : American Chemical Society (ACS). - 0893-228X .- 1520-5010. ; 29:1, s. 75-86
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Tidskriftsartikel (refereegranskat)abstract
- Activation of the aryl hydrocarbon receptor (AhR), a conserved transcription factor best known as a target for highly toxic halogenated substances such as dioxin, under normal xenobiotic-free conditions is of considerable scientific interest. We have demonstrated previously that a photoproduct of tryptophan, 6-formylindolo[3,2-b]carbazole (FICZ), fulfills the criteria for an endogenous ligand for this receptor and proposed that this compound is the enigmatic mediator of the physiological functions of AhR. Here, we describe novel light-independent pathways by which FICZ can be formed. The oxidant H2O2 was shown to convert tryptophan to FICZ on its own in the absence of light. The enzymatic deamination of tryptamine yielded indole-3-acetaldehyde (I3A), which then rearranged to FICZ and its oxidation product, indolo[3,2-b]carbazole-6-carboxylic acid (CICZ). Indole-3-pyruvate (I3P) also produced I3A, FICZ, and CICZ. Malassezia yeast species, which constitute a part of the normal skin microbiota, produce a number of AhR activators from tryptophan. We identified both FICZ and CICZ among those products. Formation of FICZ from tryptophan or I3P produces a complex mixture of indole derivatives, some of which are CYP1A1 inhibitors. These can hinder the cellular clearance of FICZ and thereby increase its power as an AhR agonist. We present a general molecular mechanism involving dehydrogenations and oxidative coupling for the formation of FICZ in which I3A is the important precursor. In conclusion, our results suggest that FICZ is likely to be formed systemically.
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| 8. |
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| 9. |
- Bergman, Jan, et al.
(författare)
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Oxidative Ring Expansion of Spirocyclic Oxindole Derivatives
- 2014
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 79:19, s. 9065-9073
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Tidskriftsartikel (refereegranskat)abstract
- Oxidation of the spirocyclic oxindole derivative, isamic acid 1, led to decarboxylation and ring expansion to quinazolino[4,5-b]quinazoline-6,8-dione 7 rather than, as previously believed, its isomer 6. The structure of 7 was confirmed by X-ray crystallography. Condensation of isatin (indole-2,3-dione) and 2-aminobenzamide led to the spirocyclic molecule, spiro[3H-indole-3,2'(1H)quinazoline]-2,4'(1H,3H)dione 8, which was also identified as an intermediate in the oxidation of isamic acid. Mild hydrolysis of 7 gave the 10-membered molecule 22. Isamic acid could easily be converted to N-nitrosoisamic acid, which when heated in ethanol underwent a ring expansion to a hydroximino derivative, 38, of compound 6. The structure of 38 was confirmed by X-ray crystallography.
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| 10. |
- Pettersson, Birgitta, et al.
(författare)
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Synthetic studies towards 1,5-benzodiazocines
- 2013
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Ingår i: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 69:12, s. 2647-2654
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Tidskriftsartikel (refereegranskat)abstract
- Anthranilonitrile reacted with phenylmagnesium bromide to yield a dianion, which when heated (similar to 120 degrees C) yielded the condensation product 2-(2-aminophenyl)-2,4-dipheny1-1,2-dihydroquinazoline 8. This heterocycle, when treated with palladium acetate, was converted into 6,12-diphenyldibenzo[b,f][1,5] diazocine 9. Methylmagnesium bromide and anthranilonitrile, under similar conditions directly gave a nitrogen-bridged diazocine, whose structure was determined by X-ray crystallography and also proven to be an analogue of Troger's base. Acid-induced condensation of 2-amino-3-methoxybenzaldehyde gave the trimeric product 45 rather than a dibenzo[b,f][1,5]diazocine.
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