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  • 11
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    Aminoguanidinium hexafluorozirconate: a new ferroelectric (2001)
    International Union of Crystallography
    Details
    Publication Date: 2001-02-01
    Description: Analysis of the atomic arrangement in anhydrous aminoguanidinium hexafluorozirconate, CN4H8ZrF6, reported by Bukvetskii, Gerasimenko & Davidovich [Koord. Khim.(1990),16, 1479–1484], led to the prediction that it is a new ferroelectric [Abrahams, Mirsky & Nielson (1996).Acta Cryst.B52, 806–809]. Initial attempts to verify the prediction were inconclusive because of the variety of closely related materials produced under the original preparation conditions. Clarification of these conditions led to the formation of pure CN4H8ZrF6and the growth of single crystals with dimensions as large as 7 × 7 × 2 mm. Highly reproducible calorimetric and dielectric permittivity anomalies reveal the Curie temperatureTc= 383 (1) K. At this temperature, the heat capacityCpexhibits an entropy change of 0.7 (1) J mol−1 K−1, while the relative permittivity ∊rexhibits an inflection and the dielectric loss a distinct peak; the dielectric anomaly atTcis observed only at the lowest (0.1–1 kHz) frequencies used. Dielectric hysteresis is demonstrable at 295 K under the application of ∼1 MV m−1alternating fields and remains observable at allT
    Print ISSN: 0021-8898
    Electronic ISSN: 1600-5767
    Topics: Geosciences , Physics
    Published by International Union of Crystallography
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    PAPER CURRENT
  • 12
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    A study on various methods of supplying propellant to an orbit insertion rocket engine (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Various types of pumps and pump drives were evaluated to determine the lightest weight system for supplying propellants to a planetary orbit insertion rocket engine. From these analyses four candidate propellant feed systems were identified. Systems Nos. 1 and 2 were both battery powered (lithium-thionyl-chloride or silver-zinc) motor driven pumps. System 3 was a monopropellant gas generator powered turbopump. System 4 was a bipropellant gas generator powered turbopump. Parameters considered were pump break horsepower, weight, reliability, transient response and system stability. Figures of merit were established and the ranking of the candidate systems was determined. Conceptual designs were prepared for typical motor driven pumps and turbopump configurations for a 1000 lbf thrust rocket engine.
    Keywords: ASTRONAUTICS (GENERAL)
    Type: TRW/DSSG-36358.001 , NASA-CR-163587 , JPL-9950-415
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 13
    Electronic Resource
    Electronic Resource
    Aminoguanidinium hexafluorozirconate: a new ferroelectric (2001)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 34 (2001), S. 47-54 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Analysis of the atomic arrangement in anhydrous aminoguanidinium hexafluorozirconate, CN4H8ZrF6, reported by Bukvetskii, Gerasimenko & Davidovich [Koord. Khim. (1990), 16, 1479–1484], led to the prediction that it is a new ferroelectric [Abrahams, Mirsky & Nielson (1996). Acta Cryst. B52, 806–809]. Initial attempts to verify the prediction were inconclusive because of the variety of closely related materials produced under the original preparation conditions. Clarification of these conditions led to the formation of pure CN4H8ZrF6 and the growth of single crystals with dimensions as large as 7 × 7 × 2 mm. Highly reproducible calorimetric and dielectric permittivity anomalies reveal the Curie temperature Tc = 383 (1) K. At this temperature, the heat capacity Cp exhibits an entropy change of 0.7 (1) J mol−1 K−1, while the relative permittivity εr exhibits an inflection and the dielectric loss a distinct peak; the dielectric anomaly at Tc is observed only at the lowest (0.1–1 kHz) frequencies used. Dielectric hysteresis is demonstrable at 295 K under the application of ∼1 MV m−1 alternating fields and remains observable at all T 〈 Tc but not at T ≥ Tc; the prediction of ferroelectricity is hence confirmed. The value of the spontaneous polarization Ps is 0.45 (9) × 10−2 C m−2 at 298 K, with piezoelectric coefficient d33 = 1.9 (5) pC N−1 and pyroelectric coefficient p3 = 4 (1) µC m−2 K−1. Tilts of less than ∼11° by the two symmetry-independent CN4H{}_{8}^{2+} ions, combined with rotations of ∼20° or less by the N—NH3 and C—(NH2)2 groups about the central C—N bond in each cation, as all H atoms rotate into or become symmetrically distributed about the planes at z = 0 or ½, allow them to conform to mirror symmetry via polar atomic displacements of ∼0.4 Å or less by N or C, and of 0.7 Å or less by H. Corresponding displacements of less than 0.08 Å within the two symmetry-independent ZrF{}_{6}^{2-} anions also result in mirror symmetry, satisfying the structural criteria required for the development of ferroelectricity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889800015508
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    Paper (German National Licenses)
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  • 14
    Electronic Resource
    Electronic Resource
    Structural studies of a carbohydrate-containing polymer present in the mucilage tubes of the diatom Berkeleya rutilans (trent.) grun.
    Amsterdam : Elsevier
    Carbohydrate Research 66 (1978), S. 103-111 
    Details
    ISSN: 0008-6215
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/S0008-6215(00)83243-7
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    Paper (German National Licenses)
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  • 15
    Electronic Resource
    Electronic Resource
    Further structural studies of the carbohydrate moiety of the allergen Ag-54 (Cla h II) from the mould Cladosporium herbarum
    Amsterdam : Elsevier
    Carbohydrate Research 214 (1991), S. 267-279 
    Details
    ISSN: 0008-6215
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0008-6215(91)80034-K
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    Paper (German National Licenses)
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  • 16
    Electronic Resource
    Electronic Resource
    Aminoguanidinium(2+) Hexafluorozirconate Monohydrate: A Co-Product of Preparing the Ferroelectric Anhydrous Salt (1998)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 54 (1998), S. 417-423 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Preparation of anhydrous aminoguanidinium(2+) hexafluorozirconate, CN4H8ZrF6, shown previously to satisfy the structural criteria for ferroelectricity [Abrahams et al. (1996). Acta Cryst. B52, 806–809], generally results in the co-formation of a series of related fluorozirconates. The structure of the monohydrate salt, one of the co-products, has been redetermined to improve understanding of the preparation pathway, locate the H atoms and compare corresponding atom positions [Gerasimenko et al. (1989). Koord. Khim. 15, 130–135]. The positions of the H atoms were not established in the latter study. All 16 H atoms in the two symmetry-independent CN4H8(2+) ions are now located and refined, with R1 = 0.0299 and S = 1.119. Both independent water molecules are disordered. Normal probability analysis reveals uncompensated error and/or underestimated uncertainty associated with ten non-H-atom position coordinates. The relative concentrations of HF, CN4H7Cl and H2ZrF6 are among the major variables controlling the formation of the related fluorozirconates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108768197020090
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  • 17
    Electronic Resource
    Electronic Resource
    Arabinogalactans in a purified allergen preparation from pollen of timothy (Phleum pratense)
    Amsterdam : Elsevier
    Phytochemistry 21 (1982), S. 1913-1919 
    Details
    ISSN: 0031-9422
    Keywords: Phleum pratense ; Poaceae ; allergen preparation ; arabinogalactan ; glycoprotein ; grass pollen ; hydroxyproline. ; timothy
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0031-9422(82)83014-8
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    Paper (German National Licenses)
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  • 18
    Electronic Resource
    Electronic Resource
    S12.19 Isolation and Characterization of a glycoprotein allergen fromaspergillus fumigatus (1993)
    Springer
    Glycoconjugate journal 10 (1993), S. 301-301 
    Details
    ISSN: 1573-4986
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01210053
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    Paper (German National Licenses)
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  • 19
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    The Storfjorden, Svalbard, 2008–2012 aftershock sequence: Seismotectonics in a polar environment (2013)
    In:  Tectonophysics
    Details
    Publication Date: 2020-02-12
    Description: A long, complex aftershock sequence has followed an Mw 6.1 mainshock in February 2008, in Storfjorden, Svalbard. Relatively located aftershock epicenters and focal mechanisms from moment tensor inversion suggest that the series took place along a NE–SW trending and steeply SSE dipping oblique-normal fault, with the total aftershock extent exceeding the mainshock rupture. The magnitude of the mainshock and the duration of the aftershock activity render the Storfjorden sequence important in terms of earthquake hazard assessment in the Svalbard region. We have evaluated all involved uncertainties and combined seismological information with background knowledge for the area, in order to achieve as sound a seismotectonic interpretation as possible. Our results clearly indicate that the activity in Storfjorden should be attributed to a previously unknown tectonic structure. In addition, there are indications of activation of secondary structures and possibly of stress triggering. These new findings affect our understanding of the region's earthquake potential.
    Language: English
    Type: info:eu-repo/semantics/article
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  • 20
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    Seismotectonics of Hornsund, Spitsbergen, European Arctic, based on moderate magnitude seismicity (2023)
    In:  XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG)
    Details
    Publication Date: 2023-06-14
    Description: Accurate seismotectonic studies on and around Spitsbergen, European Arctic, are impeded by a number of difficulties. The largely glaciated environment and the geographic distribution of land and sea restrict geotectonic mapping, as well as the deployment of dense, local seismic networks. The nature of tectonic seismicity in the region, which is episodic and dominated by moderate to low event magnitudes, imposes additionally its own challenges. So far, the best studied activity has been the Storfjorden 2008-2016 earthquake series (Mw 6.1, 21 February 2008; Mw 5.1, 29 March 2016) and background seismicity in the offshore area east of southern Spitsbergen, and to a lesser extent, seismicity in Heerland, on central Spitsbergen (mb 5.5, 18 January 1976). Despite the aforementioned challenges, the improvement of the regional seismic network from 2010 onward, has been offering enhanced insight into Svalbard seismotectonics, in particular in areas best covered by seismic station distribution. One such case, is the Hornsund area, where the calculation of moment tensor solutions was possible for two moderate magnitude, onshore events (Mw 4.3, 4 July 2015; Mw 4.6, 31 May 2017). The nearby broadband station facilitates event focal depth determination, insights into the local tectonic structure enabled by geological mapping. We will present the focal characteristics of the activity associated with these earthquakes and discuss their placement within the local and regional geotectonic setting.
    Language: English
    Type: info:eu-repo/semantics/conferenceObject
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