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  • 1
    ISSN: 1434-601X
    Keywords: PACS:23.40.-s β decay, double β decay, electron and muon capture – 27.30.+t 20 ≤ A ≤ 38 – 27.50.+e 59 ≤ A ≤ 89
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The unknown β-decay half-lives of 22 isotopes far off stability (5 〈 T Z 〈 10) in the region from Ti to Ni were measured at GSI, Darmstadt. The nuclei were produced in a fragmentation reaction of 500 A.MeV 86Kr-projectile impinging on a thick Be target. The isotopes of interest were separated and identified with the fragment separator, FRS, by a combination of Bρ,Z, and ToF techniques. An additional range separation was performed by a selective implantation into granular detectors. The spatial and time correlations of the implant with the consecutively detected β-particles were used to determine the unknown half-lives. For nuclei far off stability, β-decay chains were measured and analyzed as well, leading to an even more reliable evaluation of the lifetimes. The large discrepancies found between the measured and the theoretical values emphasize that most recent theoretical work is not an improvement over calculations made almost a decade ago.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-601X
    Keywords: PACS:25.75.-q – 25.70.Mn – 21.10.Ft – 21.10.Gv – 27.50.+e – 27.50.+j – 24.10.Pa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: Projectile fragmentation of 238U in a lead target was investigated at a bombarding energy of 750 A MeV. Isotopic production cross sections of about 250 different projectile fragments in the element range Z= 30–53 were measured with the FRagment Separator (FRS). The magnetic selection and the kinematical analysis of the measured isotopes allowed to disentangle fission and fragmentation residues. The mass loss of these residues indicates a violent collision where a large amount of energy is dissipated. The position of the fragmentation corridor defined by the measured residues was used to determine an effective proton-evaporation barrier.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-601X
    Keywords: PACS:25.85.-w Fission reactions – 25.75.-q Relativistic heavy-ion collosions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: Fragments of relativistic 750 A.MeV U-projectiles were investigated by using the fragment separator FRS for magnetic selection of reaction products including ray-tracing and ΔE-ToF techniques. For elements between Ge and Sb, measurements of isotopic yield distributions and velocities revealed three processes: fragmentation, low-energy fission, and high-energy fission. The last of these regimes is presently reported. First and second moments of distributions of mass numbers, atomic numbers and velocities of the corresponding fragments allowed us to identify 101 43Tc56 as the most probable fragment of a high energy symmetric fission reaction. Moreover, we could deduce a hypothetical mean fissioning fragmentation product 208Rn and its highly excited pre-fragmentation parent 227Ra produced in a primary abrasion reaction at an excitation energy of about 290 MeV.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1433-0563
    Keywords: Key words Extracorporeal shock wave lithotripsy • Complications • Mobile unit lithotripsy ; Schlüsselwörter Extrakorporale Stoßwellenlithotripsie • Komplikationen • Transportable ESWL
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Transportable Lithotripsiegeräte werden in zunehmendem Maße in urologischen Kliniken zur Harnsteinbehandlung eingesetzt, wenn kein festinstallierter Lithotriptor vorhanden ist bzw. eine solche Anschaffung als unrentabel angesehen wird. In der vorliegenden Studie wird überprüft, inwieweit die Komplikationsrate bei diskontinuierlicher Anwendung der ESWL mit transportablen Lithotripsiesystemen von den bekannten Komplikationsdichten aus etablierten Zentren verschieden ist. An bis zu 54 Kliniken wurde die Komplikationsrate bei diskontinuierlicher Anwendung transportabler Lithotripsiesysteme von 1993–1995 bei insgesamt 12 901 Therapien erfaßt. Schwerwiegende Komplikationen ergaben sich in insgesamt 85 Fällen (0,66 %). Die Mehrzahl davon (n = 64) waren intra- oder perirenale Hämatome; 3mal mußte nephrektomiert werden. Die Mortalität lag bei 0 %. Für die einzelnen Komplikationen lassen sich aus diesen Fallzahlen Wahrscheinlichkeiten ihres Auftretens berechnen. Insgesamt zeigt die Untersuchung, daß die ESWL mit mobilen Systemen mit der gleichen geringen Komplikationsrate angewendet werden kann, wie sie von etablierten Steinzentren bekannt ist.
    Notes: Summary An increasing number of urological departments are taking advantage of portable lithotripsy units if a system is not available in their clinic or purchase does not seem feasible; however, infrequent application of ESWL in such a setting should not increase the rate of complications. From 1993 to 1995, up to 54 urological departments using mobile lithotripsy units collected data concerning all major complications. A total of 12 901 treatments were performed which led to 85 major complications (0.66 %). Of them 64 were intrarenal or perirenal hematomas. There was no fatal complication. In three patients nephrectomy had to be performed subsequently. The probability of complications can be calculated according to these data. Overall, less frequent application of ESWL does not yield higher complication rates than those at ESWL centers where larger numbers of treatments are performed.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1434-601X
    Keywords: PACS:25.85.-W Fission reactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: Projectile fission of 750 AMeV 238U-ions interacting with a Pb target was studied by means of the spectrometer FRS, GSI-Darmstadt. One of the two fission fragments was detected with a transmission of few percent and identified in mass and charge. Low-energy fission (E* 〈 25 MeV) events were selected by their magnetic rigidity. Whereas the production of asymmetric fission events is dominated by the GDR excitation, very asymmetric fission and symmetric fission take place after a GQR or DGDR excitation or after a nuclear interaction. Cross sections of more than 250 isotopes were measured. Isotopic distributions of low-energy fission were reconstructed for elements from Se to Te. The fission modes SI, SII and SL were clearly shown in these distributions and in the mass and TKE distributions. Charge polarization and mass dispersion were deduced for each fission mode. Finally, the characteristics of the low-energy fission process explain the production rates of neutron-rich species.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1434-193X
    Keywords: [2.2](1,4)Naphthalenophanes ; [2.2](1,4)Anthracenophane ; Pentacene ; Cyclic voltammetry ; Radical cations ; ESR/ENDOR spectroscopy ; Intramolecular electron transfer ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various radical cations, in which two terminal 1,4-dimethoxybenzene units are anellated to [2.2]paracyclophane (2b•+, 3b•+), [2.2](1,4)naphthalenophane (4d•+), and anthracene bridges (5•+), have been studied by ESR and ENDOR spectroscopy. In the syn- and anti-naphthalenophane radical cations 2b•+ and 3b•+ the delocalization of the unpaired electron over both π-moieties and the distinct difference between the first and second oxidation potentials, ΔE = E20 - E10, are evidence for a substantial intramolecular electronic interaction between the two electrophores. Extension of the bridge in 4d•+ and 5 by benzo anellation results in a localized radical cation. Strong intramolecular electronic interaction between the two electrophores is found in the 1,4,8,11-tetramethoxy-pentacene radical cation (5•+). The syntheses of 4d are described.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1434-193X
    Keywords: Porphyrin-quinone systems ; Biphenylene-spacered cyclophanes ; Syntheses, structures, spectroscopic properties ; Electron-transfer rates, distance dependence of ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In continuation of previous syntheses of benzene-, naphthalene-, and anthracene-spacered porphyrin-quinone cyclophanes 1, 2, and 4, biphenylene-spacered porphyrin-quinone cyclophanes of structure 3 as the “missing link” between 2 and 4 were prepared in multistep syntheses. These donor-acceptor systems are of interest since, with regard to electron-transfer rates, they complete the series of 1, 2, and 4. As expected the electron-transfer of 3 proceeds between that of 2 and 4 in an especially steep region of distance dependences of electron-transfer rates.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1434-193X
    Keywords: Porphyrin-acceptor cyclophanes ; 7,7,8,8-Tetracyanoquinodimethane (TCNQ)-bridged porphyrins ; Electron-transfer-related properties ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Previous work on intramolecular electron-transfer compounds of the quinone-porphyrin cyclophane type with gradually increasing electron-acceptor strength was now extended to acceptor-porphyrin cyclophanes with 7,7,8,8-tetracyanoquinodimethane (TCNQ) as an especially strong electron-acceptor. The vertically stacked TCNQ-porphyrin cyclophane 1 was prepared in a multi-step synthesis. Physical properties related to structure and electron-transfer processes of 1 are reported. To determine the distance dependence of the interaction between the electron-acceptor TCNQ and the porphyrin, first results on the synthesis of the corresponding naphthalene-spacered TCNQ-porphyrin cyclophane 15 are presented.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0947-3440
    Keywords: Intramolecular electron donor-acceptor interactions ; [3.3]- and [4.4]Cyclophanes of pyrene and 1,4;5,8-naphthalenetetracarboxdiimide ; Charge transfer ; Through-space interactions ; UV/Vis spectroscopy ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electron donor-acceptor cyclophanes 1 and 2, consisting of pyrene as the donor component and 1,8;4,5-naphthalenete-tracarboxdiimide as the acceptor component fixed by methylene chains in parallel face-to-face orientations, have been synthesized. The structures, based on an X-ray analysis of 1 and on spectroscopic properties, are discussed with reference to intramolecular charge-transfer interactions and are compared to those of the related excimer models [3.3]- and [4.4]pyrenophanes 3 and 4.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0947-3440
    Keywords: Photoinduced electron-transfer, distance dependence ; Naphthalene-spacered porphyrin-quinone cyclophanes ; Synthesis, conformations, structural analysis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses, conformational and structural analyses of porphyrin-quinone cyclophanes 2 with naphthalene-spacers are presented and the findings are compared with data for previously investigated analogous benzene-spacered compounds 1. In combination with data for the biphenylene- and anthracene-spacered porphyrin-quinone cyclophanes 3 and 4, to be published in following papers, the results reported herein allow some appraisal to be made of the distance dependences of photoinduced electron-transfer from porphyrin to quinone units.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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