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ABSTRACT: Die virtuelle Endoskopie der oberen, zentralen und peripheren Atemwege (virtuelle Laryngoskopie oder virtuelle Bronchoskopie)
erzeugt eine der fiberoptischen Endoskopie vergleichbare Ansicht und kommt insbesondere zur Diagnostik von tracheobronchialen
Stenosen und Tumoren mit endoluminaler Ausdehnung zur Anwendung. Vor allem seit Einführung der Mehrzeilen-Spiral-CT lassen
sich qualitativ hochwertige Rekonstruktionen der Atemwege erstellen. Das erfolgt entweder mittels Oberflächenrekonstruktion
(Surface rendering) oder Volumenrekonstruktion (Volume rendering). Die semitransparente, farbkodierte Volumenrekonstruktion
bietet den Vorteil, dass zusätzlich zur endoluminalen Darstellung auch die Umgebungsstrukturen beurteilt werden können. Weitere
wesentliche Vorteile der virtuellen gegenüber der fiberoptischen Endoskopie sind deren Nichtinvasivität, die Möglichkeit der
Passage subtotaler Stenosen mit Beurteilung der nachgeschalteten Atemwege und Navigationshilfen. Nachteilig sind die fehlende
Farbwiedergabe und Interventionsmöglichkeiten. Im Vergleich zu anderen CT-Darstellungsformen ist virtuell-endoskopisch eine
wirklichkeitsgetreuere Beurteilung tracheobronchialer Stenosen möglich als mit axialen Schnittbildern oder multiplanaren Reformationen.
Als ergänzende Methode zur fiberoptischen Endoskopie kann die virtuelle Endoskopie der Atemwege sowohl präoperativ vor Tracheotomie,
Stenting oder Resektion als auch bei der postoperativen Verlaufsbeurteilung Verwendung finden. Die virtuelle Endoskopie wird
zunehmend assistierend bei bronchoskopischen und chirurgischen Eingriffen an den Atemwegen eingesetzt werden.
Virtual endoscopy of the upper, central and peripheral airways (virtual laryngoscopy or virtual bronchoscopy) produces endoluminal
images similar to those of fiberoptic endoscopy. In particular, virtual endoscopy is useful for the assessment of endoluminal
tumor extent and tracheobronchial stenosis. Especially since the introduction of multirow detector CT, high-resolution virtual-endoscopic
images of the airways can be reconstructed. Either surface rendering or volume rendering can be used for realistic depiction
of the airways. Semitransparent color-coded volume rendering is advantageous, because adjacent structures can be displayed
in addition to endoluminal views. A major advantage of virtual endoscopy over fiberoptic endoscopy is its non-invasiveness.
With virtual endoscopy, even a high-grade stenosis is passable, enabling evaluation of the distal airways. Disadvantages are
its inability to depict mucosal color and to perform therapeutic maneuvers. In comparison to other CT display modes, virtual
endoscopy allows a more realistic assessment of tracheobronchial stenosis than axial CT slices and multiplanar reformats.
Virtual endoscopy of the airways can be used complementary to fiberoptic endoscopy before tracheotomy, stent implantation
or lung resection and for post-operative follow-up. In the future, virtual airway endoscopy will be increasingly applied for
interactive virtual reality guidance of airway procedures such as bronchoscopy and surgery.
Der Radiologe 04/2012; 42(9):703-711. · 0.61 Impact Factor
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ABSTRACT: This article presents the lock-in thermography measurement technique applied to encapsulated organic heterojunction solar cells, built from poly(3-hexylthiophene) (P3HT) and 1-(3-methaoxycarbonyl)propyl-1-phenyl[6,6]C61 (PCBM). The realizable temperature resolution grants the possibility to visualize even very weak thermal losses in solar cells. The thermal behavior of the cells is demonstrated for different applied voltages. Especially, parallel and serial resistances can be spatially resolved. In order to explain the nonuniform behavior of the serial resistance a simplified replacement circuit of the organic cell is created, according to the Kirchhoff laws. The matrix of series and parallel resistivities allows the simulation of the currents flowing vertically through the semiconducting layer. Bias dependent simulations reveal that the considerable difference of the sheet resistances between the indium-tin-oxide (ITO) and aluminum contacts is responsible for the experimentally observed inhomogeneous temperature profiles of the organic solar cells.
Solar Energy Materials and Solar Cells 04/2010; 94:642. · 4.54 Impact Factor
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Sol. Ener. Mat. Sol. Cells. 01/2010; 94:642.
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ABSTRACT: Polymer/fullerene bulk heterojunction solar cells consisting of PDDTP:PCBM blends have been investigated and optimized. The structural properties of the photoactive layers were studied by GID-XRD, which revealed a pronounced response of photovoltaic parameters on the polymer crystallinity. In addition to P3HT, another donor polymer was found that develops crystalline domains upon annealing. We found a clear correlation between annealing time, power conversion efficiency, and polymer crystallinity. The PDDTP crystallization ability is a promising property. This is a first step toward the synthesis of low-bandgap polymers, which likewise show ability to form crystalline domains and may therefore lead to a substantial increase in efficiency.
Macromolecular Chemistry and Physics. 01/2010; 211(15):1689-1694.
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Advanced Functional Materials 03/2007; 17(7):1071 - 1078. · 10.18 Impact Factor
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ABSTRACT: Novel copolymers consisting of the alternating push-pull comonomers fluorene and thieno[3,4-b]pyrazine/quinoxaline were synthesized by a palladium-catalyzed Suzuki cross-coupling reaction in 60-80% yields. The structure of the deeply colored copolymers was confirmed with H-1 and C-13 NMR. All the new materials were characterized with spectroscopic and electrochemical methods. Bulk heterojunction organic solar cells based on some of the novel polymers in combination with the well-known fullerene acceptor [6,6]phenyl C-61-butyric acid methyl ester were fabricated, and their photovoltaic parameters were measured. (c) 2006 Wiley Periodicals, Inc.
Journal of Polymer Science Part a-Polymer Chemistry. 01/2006; 44(24):6952-6961.
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B. Maennig,
J. Drechsel,
D. Gebeyehu,
P. Simon,
F. Kozlowski,
A. Werner,
F. Li,
S. Grundmann,
S. Sonntag,
M. Koch,
K. Leo,
M. Pfeiffer, H. Hoppe,
D. Meissner,
N.S. Sariciftci,
I. Riedel,
V. Dyakonov,
J. Parisi
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ABSTRACT: We introduce a p-i-n-type heterojunction architecture for organic solar cells where the active region is sandwiched between two doped wide-gap layers. The term p-i-n means here a layer sequence in the form p-doped layer, intrinsic layer and n-doped layer. The doping is realized by controlled co-evaporation using organic dopants and leads to conductivities of 10-4 to 10-5S/cm in the p- and n-doped wide-gap layers, respectively. The photoactive layer is formed by a mixture of phthalocyanine zinc (ZnPc) and the fullerene C60 and shows mainly amorphous morphology. As a first step towards p-i-n structures, we show the advantage of using wide-gap layers in M-i-p-type diodes (metal layer–intrinsic layer–p-doped layer). The solar cells exhibit a maximum external quantum efficiency of 40% between 630-nm and 700-nm wavelength. With the help of an optical multilayer model, we optimize the optical properties of the solar cells by placing the active region at the maximum of the optical field distribution. The results of the model are largely confirmed by the experimental findings. For an optically optimized device, we find an internal quantum efficiency of around 82% under short-circuit conditions. Adding a layer of 10-nm thickness of the red material N,N-dimethylperylene-3,4:9,10-dicarboximide (Me-PTCDI) to the active region, a power-conversion efficiency of 1.9% for a single cell is obtained. Such optically thin cells with high internal quantum efficiency are an important step towards high-efficiency tandem cells. First tandem cells which are not yet optimized already show 2.4% power-conversion efficiency under simulated AM 1.5 illumination of 125mW/cm2 .
Applied Physics A 05/2004; 79(1):1-14. · 1.63 Impact Factor
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ABSTRACT: We investigated blends of poly hexylthiophene (P3HT) with copper indium diselenide nanocrystals for photovoltaic applications. Depending on the synthesis, the particles were shielded by different organic surfactants. Different concentrations of these nanoparticles were suspended in the polymer solutions and spin cast onto ITO glass. Morphological studies have been performed by atomic force microscopy and transmission electron microscopy. Films consisting of tri-n-octylphosphine oxide-capped CISe:P3HT show photovoltaic response. The best performance we obtained is an open-circuit voltage of about 1V and a photocurrent of 0.3mA/cm2 using a white light illumination intensity of 80mW/cm2.
Applied Physics A 05/2004; 79(1):59-64. · 1.63 Impact Factor
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ABSTRACT: In contrast to the left ventricle, the maximal rate of intraventricular pressure rise in the right ventricle does not occur within the isovolumic phase of the contraction. Occlusion of the pulmonary artery by inflation of a balloon during the diastole causes an isovolumic systole of the following heart beat. The canine heart-lung preparation was used to test whether dP/dtmax measured isovolumically and the peak ventricular pressure Pmax as well as the parameters derived are useful indices for the contractile state of the right ventricle.Changes only of the aortic pressure influence neither dP/dtmax, Pmax and the time values from the onset of contraction to dP/dtmax (t-dP/dtmax), nor the time to Pmax (t-Pmax). A rise in heart frequency leads to an increase in dP/dtmax and Pmax at lowered enddiastolic pressure. It does not influence the time interval t-dP/dtmax and t-Pmax. With augmented diastolic filling, dP/dtmax as well as Pmax increase, and t-dP/dtmax and t-Pmax are extended.The present study suggests that dP/dtmax and Pmax measured isovolumically provide accurate and practical measurements of right ventricular contractility, provided that changes in enddiastolic pressure and heart frequency are taken into account. The time parameters are found to be not useful.Im Gegensatz zum linken Ventrikel liegt die grte Druckanstiegsgeschwindigkeit im rechten Ventrikel gewhnlich nicht innerhalb der isovolumetrischen Kontraktionsphase. Durch Verschlu der Pulmonalarterie (Aufblasen eines Ballons) innerhalb der Diastole kann ein isovolumetrischer Verlauf der folgenden Systole erzwungen werden.Am Herz-Lungen-Prparat des Hundes wird geprft, inwieweit das isovolumetrisch gemessene dP/dtmax und der maximale Ventrikeldruck Pmax sowie die Zeit vom Beginn der Kontraktion bis dP/dtmax (t-dP/dtmax) bzw. bis Pmax (t-Pmax) als Ma fr die Kontraktilitt des rechten Ventrikels brauchbar sind.Alleinige nderung des Aortendrucks bleibt ohne Einflu auf dP/dtmax und Pmax sowie t-dP/dtmax bzw. t-Pmax. Die Erhhung der Herzfrequenz fhrt zu einer Vergrerung von dP/dtmax und Pmax bei sinkendem enddiastolischem Druck (EDP) und bleibt ohne Einflu auf t-dP/dtmax und t-Pmax.Mit Erhhung der enddiastolischen Fllung nehmen sowohl dP/dtmax als auch Pmax deutlich zu, und t-dP/dtmax und t-Pmax werden im Mittel lnger. Verbesserung (Strophanthin) oder Verschlechterung (Hypoxie) der Kontraktilitt werden bei der isometrischen Kontraktion des rechten Ventrikels von dP/dtmax und Pmax eindeutig wiedergegeben. Von den hier geprften Parametern lassen nur dP/dtmax und Pmax unter Bercksichtigung des enddiastolischen Drucks und der Herzfrequenz bei isovolumetrischer Kontraktion eindeutige Angaben ber die Kontraktilitt des rechten Ventrikels zu, whrend die Zeitparameter unbrauchbar sind.
Archiv für Kreislaufforschung 08/1976; 71(5):521-529. · 7.35 Impact Factor
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ABSTRACT: Durch vergleichende Toxizittsbestimmungen an der weien Maus und durch Ermittlung der funktionellen Entgiftung an der Katze wird gezeigt, da, bereinstimmend mit klinischen Beobachtungen, Cardiazol gegenber Novokain und Larokain eine starke entgiftende Wirkung besitzt.
Archiv für Experimentelle Pathologie und Pharmakologie 12/1935; 183(1):67-70. · 2.65 Impact Factor
