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  • 1
    Digitale Medien
    Digitale Medien
    Investigation of the high temperature behavior of strained Si1−yCy /Si heterostructures (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 1934-1937 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We report on x-ray diffraction measurements of the substitutional carbon content y in pseudomorphic Si1−yCy (y〈0.02) layers grown on (100)-oriented silicon substrate. The samples were grown by molecular beam epitaxy and investigated during post growth annealing in situ by an x-ray powder diffractometer. Despite the tensile strain in the 100-nm-thick layers and the high carbon supersaturation, the samples were stable up to 800 °C. Beyond this temperature range, the substitutional carbon content decreased exponentially during isothermal annealing. This effect can be explained by the precipitation of the carbon and the nucleation and diffusion limited growth of SiC nanocrystals. Since no strain relief by the introduction of misfit dislocations was detectible, we conclude that contrary to the mechanism of strain relief in Si1−xGex, in comparably strained Si1−yCy epilayers, the main high temperature process is precipitation. © 1995 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.358826
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  • 2
    Digitale Medien
    Digitale Medien
    Comparison of the thermal stability of Si0.603Ge0.397/Si and Si0.597Ge0.391C0.012/Si superlattice structures (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 6134-6140 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The annealing behavior of pseudomorphic Si0.603Ge0.397/Si and Si0.597Ge0.391C0.012/Si superlattice structures was studied in the temperature range between 750 °C and 900 °C. Carbon incorporation of 1.2% changes the thermal stability of SiGe structures significantly. It suppresses plastic relaxation due to an effective dislocation pinning. No relaxation of the SiGeC sample was observed during annealing up to 875 °C for 3 h. For comparison the SiGe sample relaxed at 800 °C. Carbon strongly increases the interdiffusion of Ge and Si. The activation energy of this diffusion process for a Ge content of 40% decreases from about 4.8 eV for the pure SiGe to about 2.0 eV with an additional C content of 1.2% assuming a neglectable diffusion of the carbon. This leads to a distinct modification of the Ge profile in the investigated temperature range. © 1997 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.364361
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  • 3
    Digitale Medien
    Digitale Medien
    Transport and structural properties of the top and bottom grain boundaries in YBa2Cu3O7−δ step-edge Josephson junctions (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 249-251 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We present a method to study separately the electrical transport properties of the grain boundaries (GBs) formed at the top and at the bottom edges of YBa2Cu3O7−δ(YBCO) step-edge Josephson junctions. The step-edge junctions were fabricated on (100) LaAlO3 steps using tilted Ar ion milling to define the electrodes and the microbridges. Due to the shadowing effect of the step, a continuous YBCO stripe remains along and at the bottom of the step on both sides of a microbridge. We found that the top GB is responsible for the weak link behavior of our step-edge junctions. The transport properties were correlated with the different microstructural properties of the two GBs formed at the edges of the step. © 1998 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.120700
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  • 4
    Digitale Medien
    Digitale Medien
    Anthropogenic CO2 in Southern Ocean surface waters: evidence from stable organic carbon isotopes (1997)
    Oxford, UK : Blackwell Science Ltd
    Terra nova 9 (1997), S. 0 
    Details
    ISSN: 1365-3121
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Geologie und Paläontologie
    Notizen: We present an approach for tracing the fate of anthropogenic CO2, compiling a large data set of stable organic carbon isotope ratios from surface sediments, plankton, and sinking matter in the Atlantic Ocean. The δ13C values of sinking matter are generally lower by 0.5–4.6‰ compared to the surface sediments. This difference increases with increasing latitude, which is explained by a stronger modern increase in surface water [CO2 (aq)] in the Southern Ocean relative to the Tropical/Subtropical Ocean. Preindustrial dissolved CO2 concentrations in Atlantic surface waters, estimated from the δ13Corg of surface sediments, are compared to recently measured surface water [CO2 (aq)] values taken from literature. We obtain only a slight increase in [CO2 (aq)] at lower latitudes but a significant change of about 7 ± 2 μm in high latitudinal surface waters which we attribute to anthropogenic perturbation. Our results suggest that CO2 released by human activities has been stored in Southern Ocean surface waters.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-3121.1997.d01-29.x
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  • 5
    Digitale Medien
    Digitale Medien
    Neutrophil elastase in crevicular fluid: comparison of a middle-aged general population with healthy and periodontitis groups (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of clinical periodontology 22 (1995), S. 0 
    Details
    ISSN: 1600-051X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract Neutrophil elastase (NE) was measured in crevicular fluid (GCF) collected from 3 subject groups. GCF was harvested at a single visit of subjects with periodontal health (n=21) and with periodontitis (n=28). Samples were obtained from 132 middle-aged, middle-class health conscious patients of a health maintenance organization (HMO) at baseline and 1 year later. GCF NE was higher in periodontitis than in health. Mean GCF NE of HMO subjects was much closer to health than to periodontitis. Few members of the HMO population had enzyme levels typical of periodontitis. Subjects and sites of the HMO population were segregated into 3 categories based on enzyme levels of the healthy and periodontitis subjects. Most HMO subjects and sites were in the activity category corresponding to healthy subjects. Only a small portion were in the activity category common in periodontitis. Enzyme levels in the highest activity category at both samplings were infrequent. High enzyme levels in the HMO population were not associated with attachment loss. Thus, assay of GCF NB provided little evidence of disease in a middle-aged, middle-class health conscious general population. This finding confirms an analysis of epidemiological surveys which concluded that a population such as studied here would not benefit from periodontal diagnostic testing.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-051X.1995.tb01798.x
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  • 6
    Digitale Medien
    Digitale Medien
    Vergleichsuntersuchung von Buprenorphin und Methadon im Rahmen der Erhaltungstherapie Opiatkranker (1999)
    Springer
    Der Nervenarzt 70 (1999), S. 795-802 
    Details
    ISSN: 1433-0407
    Schlagwort(e): Schlüsselwörter Opiatabhängigkeit ; Methadon ; Buprenorphin ; Erhaltungstherapie ; Key words Opioid dependence ; Methadone ; Buprenorphine ; Maintenance therapy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Summary The efficacy of buprenorphine in opioid dependent patients (n=20) was compared to methadone maintained subjects (n=20) in a randomized comparison trial. Sublingual application of buprenorphine as an alternative synthetical opioid is being compared to methadone during a 24 week study period. A trend (p=0.06) could be found in the retention rate of investigated patients being maintained on a mean dosage of 63 mg oral applicable methadone (racemat of L- and D-methadone) in comparison to the group on a mean dosage of 7,3 mg buprenorphine (sublingual tablets). The dropout-rate of 11 subjects at the end of the study in the buprenorphine group was higher when compared to the dropout-rate of 5 in the methadone group. There was no significant difference between the two groups over the treatment period in respect to additional consumption of opiates, benzodiazepines and cocaine as evaluated through urine toxicology. The result in regard to compliance over the study period demonstrates that methadone appears to be the more successful oral opioid (p=0,04). Nevertheless, efficacy of buprenorphine in maintenance could be demonstrated in the remaining subjects, and further studies with higher daily doses and a higher number of subjects have to be performed.
    Notizen: Zusammenfassung Im Rahmen der Erhaltungstherapie mit synthetischen Opioiden wurde über eine Studiendauer von 24 Wochen die Wirksamkeit von sublingual appliziertem Buprenorphin in Tablettenform mit oral verabreichtem Methadon bei 40 opiatabhängigen Patienten verglichen. In der randomisierten Studie wurden als Zielparameter die Retentionsrate (=Prozentanteil der Patienten, die über die gesamte Studiendauer im Untersuchungsprogramm verblieben und diese wie geplant beendet haben), Zusatzkonsum und Verbleibedauer definiert. Es ergab sich bei einer mittleren täglichen Dosis von 7,3 mg Buprenorphin und einer mittleren Dosierung von 63 mg Methadon eine Tendenz bezüglich der Retentionsrate (p=0,06) zugunsten der mit Methadon behandelten Gruppe. Die Ausfallsrate in der mit Buprenorphin behandelten Gruppe (n=20) war mit 11 Patienten im Vergleich zu 5 Patienten in der methadonbehandelten Gruppe (n=20) tendenziell höher. Hinsichtlich des Zusatzkonsumes von Opiaten, Benzodiazepinen und Kokain ließ sich kein signifikanter Unterschied zwischen den beiden während des Behandlungsverlaufes erheben. Methadon stellte sich, was die Verbleibedauer in der Studie betrifft, als die erfolgreichere Substanz dar (p=0,04). Weitere Studien mit höheren Dosierungen und größeren Fallzahlen müssen diesbezüglich weiteren Aufschluß bringen.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001150050514
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  • 7
    Digitale Medien
    Digitale Medien
    3-Vinyl-1H-indoles: A conformational study, electronic aspects and reactivity predictions forDiels-Alder reactions (1995)
    Springer
    Monatshefte für Chemie 126 (1995), S. 303-317 
    Details
    ISSN: 1434-4475
    Schlagwort(e): 3-Vinyl-1H-indoles ; Conformational analysis ; Diels-Alder reactivity ; Quantum chemistry calculations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Konformationsanalysen von einigen 3-Vinyl-1H-indolen, ausgehend von Röntgenstrukturgeometrien, wurden mit den Methoden der Quantenchemie und Kraftfeldmechanik durchgeführt. Die aus quantenchemischen Rechnungen erhaltenen Ladungen, Grenzorbitale und molekularen elektrostatischen Potentiale stellen verläßliche Reaktivitätsindices zur Vorhersage der Ergebnissse vonDiels-Alder-Reaktionen mit 3-Vinyl-1H-indolen dar.
    Notizen: Summary On the basis of X-ray geometries, a theoretical conformational study of some 3-vinyl-1H-indoles was performed with quantum chemistry and molecular mechanics programs. Charge, frontier orbitals, and the molecular electrostatic potential derived from quantum chemistry calculations of 3-vinyl-1H-indoles are reliable reactivity parameters to predict the outcome of theDiels-Alder reaction.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00816100
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  • 8
    Digitale Medien
    Digitale Medien
    [a]-Anellated carbazoles with antitumor activity: Synthesis and cytotoxicity (1996)
    Springer
    Monatshefte für Chemie 127 (1996), S. 97-102 
    Details
    ISSN: 1434-4475
    Schlagwort(e): 3-Vinylindoles ; Carbazoles ; Diels-Alder reactions ; Cytotoxicity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die aus den methoxysubstituierten 3-Vinylindolen1 und2 zugänglichen Cycloaddukte3,5 und7 lassen sich mitDDQ zu den coplanar-anellierten Carbazolen4,6 und8 dehydrieren. Verbindung4a, die auch durch eine Röntǵenstrukturanalyse charakterisiert wurde, zeigt signifikante Cytotoxizität gegen Humantumor-Zellinien (K562 und RXF93).
    Notizen: Summary The cycloadducts3,5, and7, readily available from methoxy-substituted 3-vinylindoles1 and2, were dehydrogenated withDDQ to the coplanar [a]-anellated carbazoles4,6, and8. Compound4a, also characterized by X-ray structural analysis, shows significant cytotoxicity against K562 und RXF393 human tumor cell lines.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00807414
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  • 9
    Digitale Medien
    Digitale Medien
    Different crystal modifications of 3aβ,4a-dihydro-4β,10-dimethyl-2-phenyl-1H,3H,5H-pyrrolo[3,4-b]carbazol-1,3-dione – crystal data and theoretical calculations (1995)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 51 (1995), S. 999-1003 
    Details
    ISSN: 1600-5740
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0108768195002333
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  • 10
    Digitale Medien
    Digitale Medien
    Dimeric 3-Vinylindoles as Potential Antitumor Active Compounds: 1,1,3,4-Tetramethyl-3-(1-methyl-1H-indol-3-yl)-1,2,3,4-tetrahydrocyclopenta[b]indole and 1,1,3-Trimethyl-4-phenylsulfonyl-3-(1-phenylsulfonyl-1H-indol-3-yl)-1,2,3,4-tetrahydrocyclopenta[b]indole (1995)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 51 (1995), S. 2572-2575 
    Details
    ISSN: 1600-5759
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0108270195007761
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