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  • 1
    Electronic Resource
    Electronic Resource
    Phase behaviour and physical properties of the cationic quaternary system tetradecyldimethylamine oxide hydrochloric acid 1-hexanol water (2000)
    Springer
    Colloid & polymer science 278 (2000), S. 137-142 
    Details
    ISSN: 1435-1536
    Keywords: Key words Small vesicles ; Phase behaviour ; Small-angle neutron scattering ; Charged surfactants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The phase behaviour and properties of the tetradecyldimethylamine oxide/HCl/hexanol/water quaternary surfactant system have been studied by means of electric conductivity, rheology, freeze-fracture transmission electron microscopy (FF-TEM) and small-angle neutron scattering (SANS). In this system the originally zwitterionic surfactant can become increasingly charged by protonation through the addition of HCl, i.e. the degree of charging can be changed continuously. An interesting, isotropic phase (L1 * phase) of low viscosity was observed for intermediate degrees of charging. From viscosity and conductivity measurements this phase can clearly be distinguished from the conventional L1 phase that is composed of micelles. Investigation of the structures present by means of FF-TEM and SANS showed that the L1 * phase is made up of unilamellar vesicles of extremely small diameter of 8–10 nm. Evidently such highly curved structures are stabilized by the electrostatic conditions in this system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050023
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  • 2
    Electronic Resource
    Electronic Resource
    Search for narrow dibaryon resonances in neutral pion photoproduction from the deuteron (2000)
    Springer
    The European physical journal 9 (2000), S. 309-311 
    Details
    ISSN: 1434-601X
    Keywords: PACS. 13.60.Le Meson production – 14.20.Pt Dibaryons – 25.20.Lj Photoproduction reactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The reaction γd↦π0 X has been measured with TAPS at MAMI in the energy range E γ = 140-300 MeV. Using the Glasgow tagging spectrometer a photon energy resolution of 0.8 MeV was achieved. The energy excitation functions of integral and differential total cross-sections show no structures of statistical significance 〉 2σ. Upper limits for the production of narrow isoscalar or isovector dibaryons with masses m? 2100 MeV/c2 were deduced. They are in the range 2-5 μb averaged over the 0.8 MeV energy resolution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100500070015
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  • 3
    Electronic Resource
    Electronic Resource
    Reliability of cranial CT versus intracerebral pressure measurement for the evaluation of generalised cerebral oedema in children (2000)
    Springer
    Pediatric radiology 30 (2000), S. 439-443 
    Details
    ISSN: 1432-1998
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objective. To examine the extent to which intracranial pressure (ICP) in children after severe brain trauma can be determined by cranial CT.¶Materials and methods. Two experienced paediatric radiologists, without any knowledge of the clinical symptoms, evaluated 124 CT scans from 65 children (average age 5.4 years) who underwent intracranial measurement of their cerebral pressure.¶Results. CT had high sensitivity (99.1 %) for ’high cerebral pressure' but a much lower specificity (78.1 %). The examiners tended to estimate ICP as ’high' even when actual ICP was low. Since therapy for lowering cerebral pressure involves potential risks, actual cerebral pressure measurement, particularly in children, should be considered before intervention (e. g. hyperventilation or trepanation). We report the change in different intracerebral fluid compartments with varying cerebral pressure and modifications of the density of the brain tissue in an inter- and intraobserver comparison.¶Conclusion. The radiologist cannot differentiate, for methodological reasons, between a change in the intracranial fluid compartments not associated with a change in ICP and one in which it is critically elevated. Before any interventional treatments such as decompression-trepanation or hyperventilation are instituted, measurement of ICP should be considered, especially in children.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002470000255
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  • 4
    Electronic Resource
    Electronic Resource
    Ein 3-D-Kapselsackmodell zur Beschreibung der biomechanischen Eigenschaften neuer Kunstlinsentypen (2000)
    Springer
    Der Ophthalmologe 97 (2000), S. 546-551 
    Details
    ISSN: 1433-0423
    Keywords: Schlüsselwörter 3-D-Kapselsackmodell ; Intraokularlinsen ; Kapselsackverformung ; Keywords Three-dimensional capsular bag model ; Intraocular lenses ; Capsular bag distortion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Background. This study quantified the geometric deformation of the capsular bag following implantation of various intraocular lenses (IOL) using a three-dimensional capsular bag model made of silicone caoutchouc. Methods. After implantation of 13 different IOLs (polymethylmethacrylate, silicone acrygel) into the artificial bag, the induced capsular bag deformation was measured and analyzed. The posterior space between IOL and capsule was examined by ultrasonographic biomicroscopy. Results. Polymethylmethacrylate IOLs with C-haptic design induced a greater deformation of the capsular bag than silicone lenses; however, both types showed a larger gap posterior to the IOL than acrygel lenses. Acrygel IOLs with different haptic design revealed only minimal deformation with close contact posteriorly. Conclusions. The presented three-dimensional model simulates the biomechanical and geometrical parameters of the vital capsular bag. Further investigations may determine a correlation of close posterior IOL contact and lens epithelial cell progression.
    Notes: Zusammenfassung Hintergrund. Zur Bestimmung einer eventuellen Verformung des Kapselsackes nach Implantation von. Intraokularlinsen (IOL) aus unterschiedlichem Material und Design wurde mit Hilfe einer geeigneten Preßvorrichtung aus Silikonkautschuck ein 3-dimensionales Modell des Kapselsackes hergestellt. Material und Methode. Nach Einsetzen von 13 verschiedenen Intraokularlinsen aus PMMA, Silikon und Acrygel in den künstlichen Kapselsack wurden die Verformungsgrade mit Hilfe von Deformierungsquotienten und -faktoren bestimmt. Mit Hilfe des Ultraschallbiomikroskopes (UBM) wurde die Größe des Spaltes zur Kapselsackrückwand ermittelt. Ergebnisse. Intraokularlinsen aus PMMA mit C-Haptik-Design bewirkten eine relativ stärkere Verformung des Kapselsackes als Linsen aus Silikon. Beide Linsentypen zeigten einen relativ breiten Spalt zwischen Optik und Kapselsackrückwand. Intraokularlinsen aus Acrygel mit atypischen Haptikkonfigurationen oder C-Haptik erzielten bessere Ergebnisse hinsichtlich der Verformung und spaltfreier Lage der Optik zur Kapselsackrückwand. Schlussfolgerungen. Ein 3-D-Silikonkautschuckmodell ist geeignet, eine mögliche Verformung des Kapselsackes nach der Implantation einer IOL und die Lage der Optik zur Kapselsackrückwand außerhalb des Auges zu simulieren. Aus den gewonnenen Ergebnissen hinsichtlich der spaltfreien Lage der Optik zur Kapselsackrückwand könnte man Rückschlüsse auf die zu erwartende Nachstarentwicklung ziehen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003470070063
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  • 5
    Electronic Resource
    Electronic Resource
    In-flight test of a continuous laser remote sensing system (1978)
    Springer
    Applied physics 15 (1978), S. 257-260 
    Details
    ISSN: 1432-0630
    Keywords: 42.60 ; 07.62
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract An airborne laser system for remote sensing has been developed and tested at flight altitudes from 500 to 1200 m. The system is based on two continuous-wave CO2 lasers (output 3 W), tunable to different wavelengths, and detects the laser radiation scattered back from earth by heterodyne reception. The feasibility of the heterodyne reception technique under aircraft environment conditions was demonstrated, and man-made SF6 clouds and different types of uncovered minerals were traced. The data obtained indicate that the measuring range of the system can be increased to satellite distance by using a larger telescope and a more powerful laser and by reducing the electrical bandwidth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00896105
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  • 6
    Electronic Resource
    Electronic Resource
    The effect of ribonuclease on the replicative forms of Sindbis virus RNA (1979)
    Springer
    Archives of virology 60 (1979), S. 131-146 
    Details
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Three species of double-stranded RNA, designated RF I, RF II, and RF III in order of decreasing size (25), are produced by ribonuclease treatment of extracts of chicken embryo cells infected for 6 hours with Sindbis virus. Only one class of replicative form RNA is present in extracts not treated with ribonuclease; this class contains some molecules which can be enzymatically cleaved to produce the other two replicative forms. At a low level of enzyme (0.001 µg/ml) the major species obtained was RF I, the replicative form of the genome. When the enzyme concentration was increased 10-, 100-, and 1000-fold, there was a progressive increase in the proportions of RF's II and III and a concomitant decrease in the proportion of RF I. The generation of RF's II and III by nuclease resulted in the ratio expected for these two species if they are produced by cleavage of RF I-like molecules. In preparations of isolated double-stranded RNA, only RF I and replicative intermediate RNA were present. Mild nuclease treatment of these preparations converted the replicative intermediates primarily to RF I. Higher enzyme levels generated greater proportions of RF II and RF III, but RF I-like molecules were the major source for these increased proportions. Treatment of the isolated naturally occurring replicative form with 0.01 µg of ribonuclease per ml cleaved some molecules migrating as RF I during gel electrophoresis into molecules which migrated as RF II and RF III.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01348029
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  • 7
    Electronic Resource
    Electronic Resource
    Ermittlung der Wärmeübergangszahl beim Erspinnen monofiler Fäden aus der Schmelze bei freier Konvektion (1977)
    Springer
    Colloid & polymer science 255 (1977), S. 1156-1164 
    Details
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Zusammenfassung Mit in der Literatur veröffentlichten Angaben wird der Fadenbildungsvorgang aus der Schmelze für Polyamid 6 und Polyäthylenterephthalat bei der freien Konvektion untersucht. Mit dem Spinnwegx s, der dem Glasumwandlungspunkt zugeordnet ist, werden der mittlere Fadendurchmesser und die Oberfläche des Polymerstrahles bestimmt. Die mittlere Wärmeübergangszahl ergibt sich aus der Wärmemenge der Polymerschmelze des monofilen Fadens, die zur Oberfläche und zur mittleren Fadentemperatur ins Verhältnis gesetzt wird. Nach dem gefundenen Ergebnis ist die mittlere Wärmeübergangszahl zum mittleren Fadendurchmesser umgekehrt proportional. Für Polyamid 6 und Polyäthylenterephthalat sind Gleichungen angegeben, die zeigen, daß die mittlere Wärmeübergangszahl zur Wärmeleitzahl des jeweiligen Polymers proportional ist. Bei den 30 ausgewerteten Meßwetten aus der Literatur wird gefunden, daß die Fadenkühlung, die sich aus dem Verhältnis der mittleren Fadentemperatur zum Spinnwegx s ergibt, bei der freien Konvektion zur Durchsatzmenge des monofilen Fadens umgekehrt proportional ist. Der Nachweis wird geführt, wie relevant der Durchmesser der Kapillârbohrung der Düse für den mittleren Fadendurchmesser und damit die mittlere Wärmeübergangszahl ist. Gleichungen zur Berechnung des mittleren Fadendurchmessers, des Spinnwegesx s, der mittleren Wärmeübergangszahl und der Fadenkühlung sind angegeben. In der Abbildung 1 läßt sich zum mittleren Fadendurchmesser die mittlere Wärmeübergangszahl ablesen. Bei der freien Konvektion ist die mittlere Wärmeübergangszahl für Polyamid 6 größer als für Polyäthylenterephthalat. Die Fadenkühlung dagegen ist für Polyamid 6 kleiner als für Polyäthylenterephthalat, da der Wärmeinhalt des Polymerstrahles des monofilen Fadens bei Polyamid 6 größer ist.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01447583
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  • 8
    Electronic Resource
    Electronic Resource
    Double- π0 photoproduction from the deuteron (2000)
    Springer
    The European physical journal 9 (2000), S. 1-4 
    Details
    ISSN: 1434-601X
    Keywords: PACS. 13.60.Le Meson production – 25.20.Lj Photoproduction reactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The photoproduction of two neutral pions from the deuteron has been studied for incident photon energies from 200 MeV to 820 MeV with the TAPS spectrometer at MAMI (Mainz Microtron). The total cross-section was determined and used to deduce the cross-section from the neutron. Due to the good statistical quality of the data Dalitz plots for the three particles in the exit channel (π0π0 N) could be constructed. The invariant mass distributions derived from them are presented in this paper. They indicate that the important reaction mechanism in the second resonance region is a sequential decay pattern involving the population of the Δ(1232)-resonance as an intermediate state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100500070047
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  • 9
    Electronic Resource
    Electronic Resource
    Photoproduction of neutral pion pairs from the proton (2000)
    Springer
    The European physical journal 9 (2000), S. 5-8 
    Details
    ISSN: 1434-601X
    Keywords: PACS. 13.60.Le Meson production – 25.20.Lj Photoproduction reactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: Double neutral pion photoproduction from the proton has been measured at MAMI for photon energies between threshold and 820 MeV. The reaction was identified by an invariant mass and missing mass analysis. From threshold up to 370 MeV the total cross-section does not exceed 30 nb. For higher energies it shows a smooth rise until it reaches a maximum of about 10 μb at E γ = 740 MeV. Dalitz plots of m 2(π0π0) versus m 2(p,π0) for seven bins of incident photon energy have been analysed. For E γ 〉 610 MeV, a strong contribution of a sequential decay is observed with the Δ(1232)-resonance as intermediate state. A comparison to model calculations shows that these sequential decays presumably originate from the D 13(1520) and also the P 11(1440)-resonance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100500070048
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  • 10
    Electronic Resource
    Electronic Resource
    On the change of polarization of positive muons in alkali halides (1975)
    Springer
    The European physical journal 22 (1975), S. 109-115 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Positive muons implanted in nonconducting solids form with high probability hydrogenlike muonium atoms (µ + e −) with properties similar to those ofU 2-centers. The influence of superhyperfine interactions with neighbor nuclei on the evolution of the polarization of the muon is investigated theoretically. The resulting muon polarization in longitudinal magnetic fields is calculated for muonicU 2-centers in some alkali halides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01322352
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