517 research outputs found
Early Localization of Bronchogenic Carcinoma
The performance of a fluorescence imaging device was compared with conventional white-light bronchoscopy in 100 patients with lung cancer, 46 patients with resected stage I non-small cell lung cancer,
10 patients with head and neck cancer, and 67 volunteers who had smoked at least 1 pack of
cigarettes per day for 25 years or more. Using differences in tissue autofluorescence between premalignant,
malignant, and normal tissues, fluorescence bronchoscopy was found to detect significantly
more areas with moderate/severe dysplasia or carcinoma in situ than conventional white-light
bronchoscopy with a similar specificity. Multiple foci of dysplasia or cancer were found in 13–24%
of these individuals. Fluorescence bronchoscopy may be an important adjunct to conventional bronchoscopic
examination to improve our ability to detect and localize premalignant and early lung cancer
lesions
Three-dimensional flow instability in a lid-driven isosceles triangular cavity
Linear three-dimensional modal instability of steady laminar two-dimensional states developing in a lid-driven cavity of isosceles triangular cross-section is investigated theoretically and experimentally for the case in which the equal sides form a rectangular corner. An asymmetric steady two-dimensional motion is driven by the steady motion of one of the equal sides. If the side moves away from the rectangular corner, a stationary three-dimensional instability is found. If the motion is directed towards the corner, the instability is oscillatory. The respective critical Reynolds numbers are identified both theoretically and experimentally. The neutral curves pertinent to the two configurations and the properties of the respective leading eigenmodes are documented and analogies to instabilities in rectangular lid-driven cavities are discussed
MoO3/CuI hybrid buffer layer for the optimization of organic solar cells based on a donor-acceptor triphenylamine
We investigate the effect of anode buffer layers (ABLs) on the performances of multi-layer heterojunction solar cells with thienylenevinylene-triphenylamine with peripheral dicyanovinylene groups (TDCV-TPA) as donor material and fullerene C-60 as acceptor. The deposition of a CuI layer between the ITO anode and the electron donor significantly improves the short-circuit current density (J(sc)) and fill factor (FF) but reduces the open-circuit voltage (V-oc). On the other hand, a MoO3 buffer layer increases the V-oc but leads to limited J(sc) and FF values, thus reducing power conversion efficiency (PCE). In this context, we show that the use of a hybrid anode buffer layer MoO3/CuI leads to a considerable improvement of the cells performances and a PCE of 2.50% has been achieved. These results are discussed on the basis of the dual function of MoO3 and CuI. While both of them reduce the hole injection barrier, CuI improves the conductivity of the organic film through an improvement of molecular order while MoO3 prevents leakage current through the diode. Finally the results of a cursory study of the ageing process provide further support to this interpretation of the effects of the various buffer layers. (C) 2012 Elsevier B.V. All rights reserved
One step synthesis of D-A-D chromophores as active materials for organic solar cells by basic condensation
Donor-Acceptor-Donor conjugated systems are synthesized in good yield by double condensation of aromatic aldehydes of triarylamines with 2,3-diaminomaleonitrile under microwave activation with trifluoroacetic acid as catalyst. The electronic properties of the compounds are investigated and discussed and a first evaluation of their potential as donor material in organic photovoltaic cells is presented
PILOT: a balloon-borne experiment to measure the polarized FIR emission of dust grains in the interstellar medium
Future cosmology space missions will concentrate on measuring the
polarization of the Cosmic Microwave Background, which potentially carries
invaluable information about the earliest phases of the evolution of our
universe. Such ambitious projects will ultimately be limited by the sensitivity
of the instrument and by the accuracy at which polarized foreground emission
from our own Galaxy can be subtracted out. We present the PILOT balloon project
which will aim at characterizing one of these foreground sources, the
polarization of the dust continuum emission in the diffuse interstellar medium.
The PILOT experiment will also constitute a test-bed for using multiplexed
bolometer arrays for polarization measurements. We present the results of
ground tests obtained just before the first flight of the instrument.Comment: 17 pages, 13 figures. Presented at SPIE, Millimeter, Submillimeter,
and Far-Infrared Detectors and Instrumentation for Astronomy VII. To be
published in Proc. SPIE volume 915
Synthèse et caractérisation de molécules conjuguées push-pull dérivées du thiéno[2,3-b]indole pour le photovoltaïque organique
Extended triphenylamine conjugated systems derivatized by perfluorophenyl groups
Two triphenylamine derivatives bearing terminal perfluorophenyl groups have been synthesized. Their HOMO. LUMO levels and electronic band gap have been evaluated by spectroscopic and electrochemical measurements and rationalized with theoretical calculations. X-ray structure analysis of crystals allowed the observation of multiple intermolecular interactions due to the presence of the perfluorophenyl pendant groups. The multiplication of these interactions explains the differences between calculated (in gas phase) and observed (in solid states) structures. (C) 2011 Elsevier Ltd. All rights reserved
Facile synthesis of 3-substituted thieno[3,2-b]furan derivatives
A facile synthesis of dimethyl 3-hydroxythieno[3,2-b]furan-2,5-dicarboxylate is reported from the available methyl thioglycolate and dimethyl acetylenedicarboxylate starting materials. This compound represents an efficient precursor for the synthesis of 3-substituted thieno[3,2-b]furan derivatives
Sharks of the order Carcharhiniformes from the British Coniacian, Santonian and Campanian (Upper Cretaceous).
Bulk sampling of phosphate-rich horizons within the British Coniacian to Campanian (Upper Cretaceous) yielded very large samples of shark and ray teeth. All of these samples yielded teeth of diverse members of the Carcharhiniformes, which commonly dominate the fauna. The following species are recorded and described: Pseudoscyliorhinus reussi (Herman, 1977) comb. nov., Crassescyliorhinus germanicus (Herman, 1982) gen. nov., Scyliorhinus elongatus (Davis, 1887), Scyliorhinus brumarivulensis sp. nov., ? Palaeoscyllium sp., Prohaploblepharus riegrafi (Müller, 1989) gen. nov., ? Cretascyliorhinus sp., Scyliorhinidae inc. sedis 1, Scyliorhinidae inc. sedis 2, Pteroscyllium hermani sp. nov., Protoscyliorhinus sp., Leptocharias cretaceus sp. nov., Palaeogaleus havreensis Herman, 1977, Paratriakis subserratus sp. nov., Paratriakis tenuis sp. nov., Paratriakis sp. indet. and ? Loxodon sp. Taxa belonging to the families ?Proscylliidae, Leptochariidae, and Carcharhinidae are described from the Cretaceous for the first time. The evolutionary and palaeoecological implications of these newly recognised faunas are discussed
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