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  • 1
    Digitale Medien
    Digitale Medien
    Measurements of the absolute external luminescence quantum efficiency in ZnSe/ZnMgSSe multiple quantum wells as a function of temperature (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 6871-6876 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We report on a novel experimental setup using a miniature integrating sphere fitted into a cryostat to measure spectrally resolved the absolute external photoluminescence quantum efficiency ηlum in the temperature range from 6 K to beyond room temperature. Direct access to ηlum is achieved by an uncomplicated method to calibrate the spatially integrated emission spectra absolutely. The fraction of light coupled out of the sphere into the detection system is in good approximation independent of the emitted wavelength and the emission characteristics of the investigated samples, due to their smallness compared with the total sphere area. This fact is proved by theoretical calculations for the sphere throughput and the irradiance within the sphere. To demonstrate the capabilities of this setup, we investigate in high quality ZnSe/ZnMgSSe 10× multiple quantum wells, the temperature dependence of the quantum efficiency, simultaneously for the quantum well and the barrier luminescence. Within a thermal activation model, three processes are found to contribute to the thermal quenching of ηlum of the quantum well luminescence. © 1998 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.368982
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  • 2
    Digitale Medien
    Digitale Medien
    Experimental comparative study of various mouthguards (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Dental traumatology 15 (1999), S. 0 
    Details
    ISSN: 1600-0595
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract— The aim of this study was to evaluate the mechanical and physical properties of several standard size commercially available mouthguards. For the purpose of objective testing, a special study model, which the various gum shield devices could be fitted onto, was developed to record tooth deflection caused by impact forces induced by a pendulum ram impact testing machine. The data measured on teeth provided with various gum shield devices were correlated with those of unprotected teeth; this enabled the individual cushioning effects of the respective devices and their specific force conduction to be evaluated. Using mouthguards considerably diminishes the deflection of the teeth subjected to stress in comparison with the row of unprotected teeth. In addition, force is transmitted to the adjacent teeth all the way to the distal regions of the row of teeth. The individual cushioning effects are directly correlated to the thickness of the material; the force distribution is determined by the rigidity of the gum shield device. The devices examined showed considerable differences with regard to force distribution and dimensioning. The study showed that this was due to the thickness of the materials, the manufacturing process and the composition of the materials of the devices examined. In comparison to laboratory-produced devices of similar material thickness, the devices that were designed to be fitted by the user achieved significantly poorer results as regards both cushioning properties and dissipation of exerted forces.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-9657.1999.tb00794.x
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  • 3
    Digitale Medien
    Digitale Medien
    Verwendung individuell hergestellter Keramikimplantate zur Sekundärrekonstruktion der knöchernen Orbita (1998)
    Springer
    Mund-, Kiefer- und Gesichtschirurgie 2 (1998), S. S98 
    Details
    ISSN: 1434-3940
    Schlagwort(e): Schlüsselwörter Sekundäre Orbitarekonstruktionen ; Alloplastische Materialien ; Stereolithographie ; Präoperative Therapieplanung ; Computergestützte Herstellung ; Key words Secondary orbital reconstruction ; Stereolithography ; Craniofacial prostheses ; Computer-aided manufacturing ; Alloplastic materials
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Summary The use of autogenous transplants and the application of intraoperatively customised alloplastic materials show, in cases of secondary orbital reconstruction, a higher postoperative morbidity caused by additional approaches to the transplant donor site. On the other hand, thorough surgical exploration and fitting of the transplants or alloplastic materials greatly prolongs operating times. For these reasons we designed ceramic implants (Bioverit) on the basis of stereolithography models and prefabricated them using a commercially available dental copy milling unit (Celay). In five cases up until now seven customised implants have been inserted for reconstruction of the lamina papyracea, zygomatic complex and infraorbital floor and rim. Encouraged by the good postoperative aesthetic and functional results, with significantly reduced operating times and morbidity in all cases, we will continue to take this technique into account for reconstruction after complex orbital fractures.
    Notizen: Zusammenfassung Sowohl die Verwendung autologer Transplantate als auch der Einsatz alloplastischer Materialien zeigen bei der Rekonstruktion der knöchernen Orbita Nachteile, die sich im wesentlichen durch die zusätzliche Entnahmemorbidität, aber auch durch verlängerte Operationszeiten ergeben. Aus diesem Grund haben wir bei ausgesuchten Fällen mit extremer Bulbusdystopie traumatischer oder kongenitaler Genese Bioveritglaskeramikimplantate auf der Basis von Stereolithographiemodellen hergestellt. Bei 5 Patienten wurden bislang insgesamt 7 Keramikimplantate im Orbitabereich inseriert, die jeweils komplikationslos einheilten und nach subjektiver und objektiver Beurteilung eine deutliche funktionelle und ästhetische Verbesserung ergaben. Damit zeigt sich hier eine Alternative zu konventionellen rekonstruktiven Verfahren, da trotz des hohen Material- und Personalaufwands dieser Technik bei nur kurzer stationärer Behandlungsdauer eine frühe Rehabilitation der betroffenen Patienten erfolgen kann.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/PL00014493
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  • 4
    Digitale Medien
    Digitale Medien
    Determination of the neutron electric form factor in the D(e,e′n)p reaction and the influence of nuclear binding (1999)
    Springer
    The European physical journal 5 (1999), S. 131-135 
    Details
    ISSN: 1434-601X
    Schlagwort(e): PACS: 25.30.Fj Nuclear Reactions: Inelastic electron scattering to continuum – 14.20.Dh Properties of Specific Particles: Protons and neutrons – 13.40.Gp Electromagnetic form factors – 25.10.+s Nuclear reactions involving few–nucleon systems
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract: The electric form factor of the neutron G E,n has been determined at the Mainz Microtron MAMI at the low momentum transfer Q 2= 0.15 (GeV/c)2 in a measurement of the recoil polarisation ratio P x/Pz in the quasifree reaction D(e,e′n)p. At this Q 2 the influence of the nuclear binding is strong. A purely kinematical model is used to get some insight into the effect of the initial Fermi momentum distribution of the neutron. The influence of the final state interaction is determined quantitatively by a model of Arenhövel et al.. After the corresponding corrections a value of G E,n(0.15 (GeV/c)2) = 0.0481±0.0065stat±0.0053syst is obtained.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s100500050268
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  • 5
    Digitale Medien
    Digitale Medien
    Die chirurgische Therapie des Gesichtshautbasalioms (1999)
    Springer
    Der Chirurg 70 (1999), S. 265-269 
    Details
    ISSN: 1433-0385
    Schlagwort(e): Key words: Basal cell carcinoma ; Micrographic surgery ; Recurrence rate ; Reconstruction. ; Schlüsselwörter: Basaliom ; mikrographische Chirurgie ; Rezidivrate ; plastische Deckung.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung. Aus dem Patientengut der Klinik und Poliklinik für Mund-, Kiefer- und Gesichtschirurgie des Universitätsklinikums Tübingen wurden die Daten von 673 Patienten mit 1301 Basaliomen, welche im Zeitraum von 1977 bis 1992 behandelt wurden, retrospektiv katamnestisch analysiert. Klinisch-morphologische und therapeutische Kriterien, wie Tumorlokalisation und -ausdehnung, spezifische Vorbehandlungen, Histopathologie, Art und Weise der Tumorablation sowie der jeweils verwendeten plastisch-rekonstruktiven Maßnahmen wurden im einzelnen analysiert. Durch Einsatz der mikrographischen Chirurgie können die Gewebedefekte, speziell in den Problemzonen des Augen- und Nasenbereiches, kleinstmöglich gehalten werden. Damit werden günstige Voraussetzungen für die anschließende plastisch-rekonstruktive Defektdeckung und eine höchstmögliche Sicherheit für die Tumorfreiheit des angrenzenden Gewebes geschaffen. Die Daten von Patienten mit Basaliomrezidiven wurden in Korrelation mit den jeweiligen Untersuchungsergebnissen von Patienten mit primärer Tumormanifestation dargestellt. Als besonders bedeutend zeigte sich hierbei der Vergleich der jeweiligen Tumorlokalisationen sowie der histopathologischen Subdifferenzierung. Durch die Ergebnisse unserer Untersuchung konnte bestätigt werden, daß nach wie vor die chirurgische Excision des Basalioms, mit ausreichendem Sicherheitsabstand und histopathologischer Tumor- und Schnittrandkontrolle, die Therapie der Wahl ist.
    Notizen: Summary. The present investigation reviews the history of 673 patients having undergone surgical treatment for 1301 BCC of the face between 1977 and 1992 at our department. Based on this series the features with bearing on the surgical strategy, such as type, size and location of the lesions, will be outlined. Emphasis is put on the variants of local flap reconstruction and skin grafting techniques, particularly in the problem zones of the nose and eyelids, where no excess skin for closure of the defect is available. Throughout the whole series histologic control of the adequacy of marginal and deep tumor resection was performed. It became obvious that the required ranges for clearance to tumor edges and removal in depth cannot be predefined arbitrarily or on pure clinical judgement. Frequently a two-stage procedure of resection and repair will be necessitated. Recurrences during the mandatory follow-up were thoroughly reassessed to identify the reason for failure (e. g. accuracy of histologic category, multifocal growth, predisposition) and related to the time span from primary excision. Our series confirms that morphologically controlled surgical excision of the BCC of the face and subsequent application of reconstructive techniques produces both safe oncologic and esthetic results.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001040050641
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  • 6
    Digitale Medien
    Digitale Medien
    Dietary fiber reduces the antioxidative effect of a carotenoid and α-tocopherol mixture on LDL oxidation ex vivo in humans (1999)
    Springer
    European journal of nutrition 38 (1999), S. 278-285 
    Details
    ISSN: 1436-6215
    Schlagwort(e): Key words Carotenoids –α-tocopherol – dietary fiber – LDL oxidation – humans
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Medizin
    Notizen: Summary Background: Antioxidant concentrations in low density lipoproteins (LDL) are an important determinant for their susceptability to oxidation and can be modulated by dietary intake. Aim of the study: In the present study, the influence of dietary fiber on the antioxidant enrichment and the oxidation resistance of LDL after antioxidant supplementation is investigated. Method: An antioxidant supplement consisting of β-carotene, lycopene, lutein, canthaxanthin and α-tocopherol was given to six young women together with a standard meal. Using a cross-over study design, each subject received the standard meal without additional dietary fiber and enriched with pectin, guar, or cellulose in a random order. To determine the resistance of LDL against copper ion-induced oxidation, the formation of conjugated dienes was measured. Results: Eight, 10, and 24 hours after antioxidant supplementation the isolated LDL revealed significantly (p 〈 0.05) increased antioxidant concentrations; addition of pectin, guar, or cellulose to the meal depressed this increase. Concomitantly, the observed increase in the resistance of LDL against oxidation (measured as lag phase) was lower with dietary fiber supplementation than that found without. On average, pectin, guar, and cellulose reduced the increase of the lag phase (measured without addition of dietary fiber) by 38%, 22%, and 18%, respectively. Conclusions: These results indicate that dietary fiber supplementation decreases the antioxidative effect of a supplement consisting of carotenoids and α-tocopherol in LDL, an effect that is likely to be mediated by a reduced bioavailability of these antioxidants in the gut.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003940050078
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  • 7
    Digitale Medien
    Digitale Medien
    Photoemission of spinpolarized electrons from strained GaAsP (1996)
    Springer
    Applied physics 63 (1996), S. 203-206 
    Details
    ISSN: 1432-0630
    Schlagwort(e): 79.60
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Strained layer GaAs.95P.05 photo cathodes are presented, which emit electron beams spinpolarized to a degree of P = 75% typically. Quantum yields around QE = 0.4% are observed routinely. The figure of merit P2 × QE = 2.3 × 10−3 is comparable to that of the best strained layer cathodes reported in literature. The optimum wavelength of irradiating light around 830 nm is in convenient reach of Ti:sapphire lasers or diode lasers respectively. The cathodes are produced using MOCVD-techniques. A GaAs.55P.45-GaAs.85P.15 superlattice structure prevents the migration of dislocations from the substrate and bottom layers to the strained overlayer. The surface is protected by an arsenic layer so that no chemical cleaning is necessary before installation into vacuum. The source of polarized electrons attached to the Mainz race track microtron MAMI works with such cathodes now. More than 1000 hours beamtime have been performed successfully.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01567651
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  • 8
    Digitale Medien
    Digitale Medien
    Rapid communication Photoemission of spinpolarized electrons from strained GaAsP (1996)
    Springer
    Applied physics 63 (1996), S. 203-206 
    Details
    ISSN: 1432-0630
    Schlagwort(e): PACS79.60
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract. Strained layer GaAs $_{.95}$ P $_{.05}$ photo cathodes are presented, which emit electron beams spinpolarized to a degree of P = 75% typically. Quantum yields around QE = 0.4% are observed routinely. The figure of merit P $^2 \times $ QE = 2.3 $\times 10^{-3}$ is comparable to that of the best strained layer cathodes reported in literature. The optimum wavelength of irradiating light around $830\;{\rm nm}$ is in convenient reach of Ti:sapphire lasers or diode lasers respectively. The cathodes are produced using MOCVD-techniques. AaAs $_{.55}$ P $_{.45}$ –GaAs $_{.85}$ P $_{.15}$ superlattice structure prevents the migration of dislocations from the substrate and bottom layers to the strained overlayer. The surface is protected by anarsenic layer so that no chemical cleaning is necessary before installation into vacuum. The source of polarized electrons attached to the Mainz race track microtron MAMI works with such cathodes now. More than 1000 hours beamtime have been performed successfully.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01567651
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  • 9
    Digitale Medien
    Digitale Medien
    Factor V inhibitor associated with cold agglutinin disease (1998)
    Springer
    Annals of hematology 76 (1998), S. 49-50 
    Details
    ISSN: 1432-0584
    Schlagwort(e): Key words Factor V ; Deficiency ; Acquired ; Cold agglutinin ; Inhibitor
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  An 81-year-old man known to have a stable cold agglutinin syndrome presented with a progressive cerebral hemorrhage. Coagulation tests revealed prolonged APTT and prothrombin time and severely decreased factor V activity, which could not be normalized by mixing with normal plasma. The patient appeared refractory to substitution with fresh-frozen plasma, suggesting the presence of a circulating inhibitor specific for factor V. To our knowledge, this is the first case of a lymphoproliferative disease leading to a cold agglutinin syndrome and a putative inhibitor of factor V. In patients with paraproteinemia presenting with bleeding diathesis, the presence of a circulating inhibitor of a specific coagulation factor must be considered.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002770050361
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  • 10
    Digitale Medien
    Digitale Medien
    Modifications in the B10 and B26–30 regions of the B chain of human insulin alter affinity for the human IGF-I receptor more than for the insulin receptor (1997)
    Springer
    Diabetologia 40 (1997), S. S54 
    Details
    ISSN: 1432-0428
    Schlagwort(e): Keywords Insulin ; insulin analogues ; insulin receptor ; insulin-like growth factor-I receptor ; proliferation ; mammary epithelial cells.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Inversion of the natural sequence of the B chain of human insulin (HI) from ProB28LysB29 to LysB28ProB29 generates an insulin analogue with reduced tendency to self-associate. Since this substitution increases the homology of insulin to insulin-like growth factor-I (IGF-I), we have examined the affinity of a series of insulin analogues with the general modified structure XaaB28ProB29 HI for binding to both human placental insulin and IGF-I receptors. The XaaB28ProB29 HI series is approximately equipotent to HI in binding to the insulin receptor with the exception of when Xaa = Phe, Trp, Leu, Ile, and Gly (40–60 % relative to HI). Substitution with basic residues in the B28 position increased the relative affinity to the IGF-I receptor approximately 1.5−2-fold (ArgB28ProB29 〉 OrnB28ProB29 = LysB28ProB29). Substitution with acidic residues reduced relative affinity for the IGF-I receptor approximately 2-fold (CyaB28ProB29 = GluB28ProB29 〉 AspB28ProB29). Combination of AspB10 substitution in conjunction with a modification in the B28–29 position (e.g. AspB10LysB28ProB29 HI) showed an additional 2-fold selective increase in affinity for the IGF-I receptor, suggesting that these two effects are additive. Addition of Arg residues at B31–32, on the backbone of either HI or AspB10 HI, increased affinity for the IGF-I receptor 10 and 28 fold, respectively, compared to HI, confirming the significance of enhanced positive charge at the C-terminal end of the insulin B-chain in increasing selectivity for the IGF-I receptor. This relative increase in IGF-I receptor affinity correlated largely, but not completely, with enhanced growth promoting activity in human mammary epithelial cells. In the case of LysB28ProB29 HI, growth activity correlated with dissociation kinetics from the insulin receptor which were shown to be identical with those of human insulin. [Diabetologia (1997) 40: S 54–S 61]
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001250051402
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