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  • 1
    Publikationsdatum: 2012-09-08
    Beschreibung: Amorphous metal-oxide semiconductors have emerged as potential replacements for organic and silicon materials in thin-film electronics. The high carrier mobility in the amorphous state, and excellent large-area uniformity, have extended their applications to active-matrix electronics, including displays, sensor arrays and X-ray detectors. Moreover, their solution processability and optical transparency have opened new horizons for low-cost printable and transparent electronics on plastic substrates. But metal-oxide formation by the sol-gel route requires an annealing step at relatively high temperature, which has prevented the incorporation of these materials with the polymer substrates used in high-performance flexible electronics. Here we report a general method for forming high-performance and operationally stable metal-oxide semiconductors at room temperature, by deep-ultraviolet photochemical activation of sol-gel films. Deep-ultraviolet irradiation induces efficient condensation and densification of oxide semiconducting films by photochemical activation at low temperature. This photochemical activation is applicable to numerous metal-oxide semiconductors, and the performance (in terms of transistor mobility and operational stability) of thin-film transistors fabricated by this route compares favourably with that of thin-film transistors based on thermally annealed materials. The field-effect mobilities of the photo-activated metal-oxide semiconductors are as high as 14 and 7 cm(2) V(-1) s(-1) (with an Al(2)O(3) gate insulator) on glass and polymer substrates, respectively; and seven-stage ring oscillators fabricated on polymer substrates operate with an oscillation frequency of more than 340 kHz, corresponding to a propagation delay of less than 210 nanoseconds per stage.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kim, Yong-Hoon -- Heo, Jae-Sang -- Kim, Tae-Hyeong -- Park, Sungjun -- Yoon, Myung-Han -- Kim, Jiwan -- Oh, Min Suk -- Yi, Gi-Ra -- Noh, Yong-Young -- Park, Sung Kyu -- England -- Nature. 2012 Sep 6;489(7414):128-32. doi: 10.1038/nature11434.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Flexible Display Research Center, Korea Electronics Technology Institute, Seongnam 463-816, Korea.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22955624" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Publikationsdatum: 2014-10-14
    Beschreibung: Alzheimer's disease is the most common form of dementia, characterized by two pathological hallmarks: amyloid-beta plaques and neurofibrillary tangles. The amyloid hypothesis of Alzheimer's disease posits that the excessive accumulation of amyloid-beta peptide leads to neurofibrillary tangles composed of aggregated hyperphosphorylated tau. However, to date, no single disease model has serially linked these two pathological events using human neuronal cells. Mouse models with familial Alzheimer's disease (FAD) mutations exhibit amyloid-beta-induced synaptic and memory deficits but they do not fully recapitulate other key pathological events of Alzheimer's disease, including distinct neurofibrillary tangle pathology. Human neurons derived from Alzheimer's disease patients have shown elevated levels of toxic amyloid-beta species and phosphorylated tau but did not demonstrate amyloid-beta plaques or neurofibrillary tangles. Here we report that FAD mutations in beta-amyloid precursor protein and presenilin 1 are able to induce robust extracellular deposition of amyloid-beta, including amyloid-beta plaques, in a human neural stem-cell-derived three-dimensional (3D) culture system. More importantly, the 3D-differentiated neuronal cells expressing FAD mutations exhibited high levels of detergent-resistant, silver-positive aggregates of phosphorylated tau in the soma and neurites, as well as filamentous tau, as detected by immunoelectron microscopy. Inhibition of amyloid-beta generation with beta- or gamma-secretase inhibitors not only decreased amyloid-beta pathology, but also attenuated tauopathy. We also found that glycogen synthase kinase 3 (GSK3) regulated amyloid-beta-mediated tau phosphorylation. We have successfully recapitulated amyloid-beta and tau pathology in a single 3D human neural cell culture system. Our unique strategy for recapitulating Alzheimer's disease pathology in a 3D neural cell culture model should also serve to facilitate the development of more precise human neural cell models of other neurodegenerative disorders.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4366007/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4366007/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Choi, Se Hoon -- Kim, Young Hye -- Hebisch, Matthias -- Sliwinski, Christopher -- Lee, Seungkyu -- D'Avanzo, Carla -- Chen, Hechao -- Hooli, Basavaraj -- Asselin, Caroline -- Muffat, Julien -- Klee, Justin B -- Zhang, Can -- Wainger, Brian J -- Peitz, Michael -- Kovacs, Dora M -- Woolf, Clifford J -- Wagner, Steven L -- Tanzi, Rudolph E -- Kim, Doo Yeon -- 5P01AG15379/AG/NIA NIH HHS/ -- 5R37MH060009/MH/NIMH NIH HHS/ -- P01 AG004953/AG/NIA NIH HHS/ -- P01 AG015379/AG/NIA NIH HHS/ -- P30 HD018655/HD/NICHD NIH HHS/ -- P30 NS045776/NS/NINDS NIH HHS/ -- P50 AG005134/AG/NIA NIH HHS/ -- R01 AG014713/AG/NIA NIH HHS/ -- R01 NS045860/NS/NINDS NIH HHS/ -- R21 AG031483/AG/NIA NIH HHS/ -- RF1 AG048080/AG/NIA NIH HHS/ -- England -- Nature. 2014 Nov 13;515(7526):274-8. doi: 10.1038/nature13800. Epub 2014 Oct 12.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129, USA [2]. ; 1] Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129, USA [2] Division of Mass Spectrometry Research, Korea Basic Science Institute, Cheongju-si, Chungbuk 363-883, South Korea [3]. ; 1] Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129, USA [2] Institute of Reconstructive Neurobiology, Life and Brain Center, University of Bonn and Hertie Foundation, 53127 Bonn, Germany. ; Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129, USA. ; FM Kirby Neurobiology Center, Boston Children's Hospital and Harvard Stem Cell Institute, Boston, Massachusetts 02115, USA. ; The Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142, USA. ; Institute of Reconstructive Neurobiology, Life and Brain Center, University of Bonn and Hertie Foundation, 53127 Bonn, Germany. ; Department of Neurosciences, University of California, San Diego, La Jolla, California 92093, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25307057" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Alzheimer Disease/genetics/*metabolism/*pathology ; Amyloid beta-Peptides/chemistry/genetics/metabolism ; Cell Culture Techniques/*methods ; Cell Differentiation ; Drug Evaluation, Preclinical/methods ; Extracellular Space/metabolism ; Glycogen Synthase Kinase 3/metabolism ; Humans ; Microtubule-Associated Proteins/metabolism ; *Models, Biological ; Neural Stem Cells/*metabolism/pathology ; Neurites/metabolism ; Phosphorylation ; Presenilin-1/metabolism ; Protein Aggregation, Pathological ; Reproducibility of Results ; tau Proteins/chemistry/metabolism
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Publikationsdatum: 2010-12-15
    Beschreibung: Elevated levels of formaldehyde (HCHO) along the ship corridors have been observed by satellite sensors, such as ESA/ERS-2 GOME (Global Ozone Monitoring Experiment), and were also simulated by global 3-D chemistry-transport models. In this study, three likely sources of the elevated HCHO levels in the ship plumes as well as their contributions to the elevated HCHO levels (budget) were investigated using a newly-developed ship-plume photochemical/dynamic model: (1) primary HCHO emission from ships; (2) secondary HCHO production via the atmospheric oxidation of non-methane volatile organic compounds (NMVOCs) emitted from ships; and (3) atmospheric oxidation of CH4 within the ship plumes. For this ship-plume modelling study, the ITCT 2K2 (Intercontinental Transport and Chemical Transformation 2002) ship-plume experiment, which was carried out about 100 km off the coast of California on 8 May 2002 (11:00 local standard time), was chosen as a base study case because it is the best defined in terms of (1) meteorological data, (2) in-plume chemical composition, and (3) background chemical composition. From multiple ship-plume model simulations for the ITCT 2K2 ship-plume experiment case, CH4 oxidation by elevated levels of in-plume OH radicals was found to be the main factor responsible for the elevated levels of HCHO in the ITCT 2K2 ship-plume. More than ~88% of the HCHO for the ITCT 2K2 ship-plume is produced by this atmospheric chemical process, except in the areas close to the ship stacks where the main source of the elevated HCHO levels would be primary HCHO from the ships (due to the deactivation of CH4 oxidation from the depletion of in-plume OH radicals). Because of active CH4 oxidation by OH radicals, the instantaneous chemical lifetime of CH4 (τCH4) decreased to ~0.45 yr inside the ship plume, which is in contrast to τCH4 of ~1.1 yr in the background (up to ~41% decrease) for the ITCT 2K2 ship-plume case. A variety of likely ship-plume situations at three different latitudinal locations within the global ship corridors was also studied to determine the enhancements in the HCHO levels in the marine boundary layer (MBL) influenced by ship emissions. It was found that the ship-plume HCHO levels could be 19.9–424.9 pptv higher than the background HCHO levels depending on the latitudinal locations of the ship plumes (i.e., intensity of solar radiation and temperature), MBL stability and NOx emission rates. On the other hand, NMVOC emissions from ships were not found to be a primary source of photochemical HCHO production inside ship plumes due to their rapid and individual dilution. However, the diluted NMVOCs would contribute to the HCHO productions in the background air.
    Print ISSN: 1680-7316
    Digitale ISSN: 1680-7324
    Thema: Geologie und Paläontologie
    Publiziert von Copernicus im Namen von European Geosciences Union.
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Publikationsdatum: 2012-11-16
    Beschreibung: For a case study of Typhoon Ewiniar performed with a mesoscale model, we compare stratospheric gravity wave (GW) momentum flux determined from temperature variances by applying GW polarization relations and by assuming upward propagating waves, with GW momentum flux calculated from model winds which is considered as a reference. The temperature-based momentum-flux profile exhibits positive biases relative to the reference, which fluctuate significantly with altitude. The vertically-averaged magnitude of the positive biases is about 14% of the reference momentum flux. We found that this deviation from the reference stems from the interference between upward and downward propagating waves. The downward propagating GWs are due mainly to partial reflections of upward propagating waves at altitudes where the background wind and stability change with height. When the upward and downward propagating waves are decomposed and their momentum fluxes are calculated separately from temperature perturbations, the fraction of the momentum flux arising from the downward propagating waves is about 4.5–8.2% of that from the upward propagating waves. The net momentum flux of upward and downward propagating GWs agrees well with the reference from the model wind perturbations. The implications of this study for the GW momentum-flux observations from satellites are discussed.
    Print ISSN: 1680-7316
    Digitale ISSN: 1680-7324
    Thema: Geologie und Paläontologie
    Publiziert von Copernicus im Namen von European Geosciences Union.
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Publikationsdatum: 2012-02-29
    Beschreibung: For a case study of Typhoon Ewiniar performed with a mesoscale model, we compare stratospheric gravity wave (GW) momentum flux determined from temperature variances by applying GW polarization relations and by assuming upward propagating waves with GW momentum flux calculated from model winds, which is considered as a reference. The temperature-based momentum-flux profile exhibits positive biases which fluctuate with altitude and have peak values of 17–39% at 20–40 km. We found that this deviation stems from the interference between upward and downward propagating waves. The downward propagating GWs are due mainly to partial reflections of upward propagating waves at altitudes where the background wind and stability change with height. When the upward and downward propagating waves are decomposed and their momentum fluxes are calculated separately from temperature perturbations, the fraction of the momentum flux arising from the downward propagating waves is about 4.5–8.2%. The net momentum flux of upward and downward propagating GWs agrees well with the reference from the model wind perturbations. Global distributions of GW momentum flux can be deduced from satellite measurements of temperatures also employing GW polarization relations but using different analysis methods. The implications of this study for the GW momentum-flux observations from satellites are discussed.
    Digitale ISSN: 1680-7375
    Thema: Geologie und Paläontologie
    Publiziert von Copernicus im Namen von European Geosciences Union.
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Publikationsdatum: 2012-07-17
    Beschreibung: Convective gravity wave (GW) sources are spatially localized and emit at the same time waves with a wide spectrum of phase speeds. Any wave analysis therefore compromises between spectral and spatial resolution. Future satellite borne limb imagers will for a first time provide real 3-D volumes of observations. These volumes will be however limited which will impose further constraints on the analysis technique. In this study a three dimensional few-wave approach fitting sinusoidal waves to limited 3-D volumes is introduced. The method is applied to simulated GWs above typhoon Ewiniar and GW momentum flux is estimated from temperature fluctuations. Phase speed spectra as well as average profiles of positive, negative and net momentum fluxes are compared to momentum flux estimated by Fourier transform as well as spatial averaging of wind fluctuations. The results agree within 10–20%. The few-wave method can also reveal the spatial orientation of the GWs with respect to the source. The relevance of the results for different types of measurements as well as its applicability to model data is discussed.
    Print ISSN: 1867-1381
    Digitale ISSN: 1867-8548
    Thema: Geologie und Paläontologie
    Publiziert von Copernicus im Namen von European Geosciences Union.
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Publikationsdatum: 2012-02-20
    Beschreibung: Convective gravity wave (GW) sources are spatially localized and emit at the same time waves with a wide spectrum of phase speeds. Any wave analysis therefore compromises between spectral and spatial resolution. Future satellite borne limb imagers will for a first time provide real 3d volumes of observations. These volumes will be however limited which will impose further constraints on the analysis technique. In this study a three dimensional few-wave appoach fitting sinusoidal waves to limited 3-D volumes is introduced. The method is applied to simulated GWs above typhoon Ewiniar and GW momentum flux is estimated from temperature fluctuations. Phase speed spectra as well as average profiles of positive, negative and net momentum fluxes are compared to momentum flux estimated by Fourier transform as well as spatial averaging of wind fluctuations. The results agree within 10–20%. The few-wave method can also reveal the spatial orientation of the GWs with respect to the source. The relevance of the results for different types of measurements as well as its applicability to model data is discussed.
    Digitale ISSN: 1867-8610
    Thema: Geologie und Paläontologie
    Publiziert von Copernicus im Namen von European Geosciences Union.
    Standort Signatur Erwartet Verfügbarkeit
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