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  • Cambridge University Press  (2)
  • De Gruyter  (2)
  • Nature Publishing Group (NPG)  (2)
  • 1
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    Non-blinking semiconductor nanocrystals (2009)
    Nature Publishing Group (NPG)
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    Publication Date: 2009-05-12
    Description: The photoluminescence from a variety of individual molecules and nanometre-sized crystallites is defined by large intensity fluctuations, known as 'blinking', whereby their photoluminescence turns 'on' and 'off' intermittently, even under continuous photoexcitation. For semiconductor nanocrystals, it was originally proposed that these 'off' periods corresponded to a nanocrystal with an extra charge. A charged nanocrystal could have its photoluminescence temporarily quenched owing to the high efficiency of non-radiative (for example, Auger) recombination processes between the extra charge and a subsequently excited electron-hole pair; photoluminescence would resume only after the nanocrystal becomes neutralized again. Despite over a decade of research, completely non-blinking nanocrystals have not been synthesized and an understanding of the blinking phenomenon remains elusive. Here we report ternary core/shell CdZnSe/ZnSe semiconductor nanocrystals that individually exhibit continuous, non-blinking photoluminescence. Unexpectedly, these nanocrystals strongly photoluminesce despite being charged, as indicated by a multi-peaked photoluminescence spectral shape and short lifetime. To model the unusual photoluminescence properties of the CdZnSe/ZnSe nanocrystals, we softened the abrupt confinement potential of a typical core/shell nanocrystal, suggesting that the structure is a radially graded alloy of CdZnSe into ZnSe. As photoluminescence blinking severely limits the usefulness of nanocrystals in applications requiring a continuous output of single photons, these non-blinking nanocrystals may enable substantial advances in fields ranging from single-molecule biological labelling to low-threshold lasers.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wang, Xiaoyong -- Ren, Xiaofan -- Kahen, Keith -- Hahn, Megan A -- Rajeswaran, Manju -- Maccagnano-Zacher, Sara -- Silcox, John -- Cragg, George E -- Efros, Alexander L -- Krauss, Todd D -- England -- Nature. 2009 Jun 4;459(7247):686-9. doi: 10.1038/nature08072.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of Rochester, Rochester, New York 14627, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19430463" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 2
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    Small molecule inhibition of the KRAS-PDEdelta interaction impairs oncogenic KRAS signalling (2013)
    Nature Publishing Group (NPG)
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    Publication Date: 2013-05-24
    Description: The KRAS oncogene product is considered a major target in anticancer drug discovery. However, direct interference with KRAS signalling has not yet led to clinically useful drugs. Correct localization and signalling by farnesylated KRAS is regulated by the prenyl-binding protein PDEdelta, which sustains the spatial organization of KRAS by facilitating its diffusion in the cytoplasm. Here we report that interfering with binding of mammalian PDEdelta to KRAS by means of small molecules provides a novel opportunity to suppress oncogenic RAS signalling by altering its localization to endomembranes. Biochemical screening and subsequent structure-based hit optimization yielded inhibitors of the KRAS-PDEdelta interaction that selectively bind to the prenyl-binding pocket of PDEdelta with nanomolar affinity, inhibit oncogenic RAS signalling and suppress in vitro and in vivo proliferation of human pancreatic ductal adenocarcinoma cells that are dependent on oncogenic KRAS. Our findings may inspire novel drug discovery efforts aimed at the development of drugs targeting oncogenic RAS.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zimmermann, Gunther -- Papke, Bjorn -- Ismail, Shehab -- Vartak, Nachiket -- Chandra, Anchal -- Hoffmann, Maike -- Hahn, Stephan A -- Triola, Gemma -- Wittinghofer, Alfred -- Bastiaens, Philippe I H -- Waldmann, Herbert -- England -- Nature. 2013 May 30;497(7451):638-42. doi: 10.1038/nature12205. Epub 2013 May 22.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemical Biology, Max Planck Institute of Molecular Physiology, D-44227 Dortmund, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23698361" target="_blank"〉PubMed〈/a〉
    Keywords: Adenocarcinoma/drug therapy/genetics/metabolism ; Animals ; Benzimidazoles/*chemistry/metabolism/*pharmacology/therapeutic use ; Binding Sites ; Carcinoma, Pancreatic Ductal/drug therapy/genetics/metabolism ; Cell Line ; Cell Line, Tumor ; Cell Proliferation/drug effects ; Cyclic Nucleotide Phosphodiesterases, Type 6/antagonists & ; inhibitors/chemistry/*metabolism ; Dogs ; Humans ; Hydrogen Bonding ; MAP Kinase Signaling System/drug effects ; Mice ; Mice, Nude ; Mitogen-Activated Protein Kinases/metabolism ; Models, Molecular ; Molecular Conformation ; Neoplasm Transplantation ; Oncogene Protein p21(ras)/*antagonists & inhibitors/genetics/*metabolism ; Protein Binding/drug effects ; Signal Transduction/*drug effects
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 3
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    Über Brommesoporphyrin und die Reduktion von Blut- und Gallenfarbstoff bei Gegenwart von kolloidalem Palladium. (1914)
    De Gruyter
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    Publication Date: 1914-01-01
    Print ISSN: 0018-4888
    Topics: Biology , Chemistry and Pharmacology
    Published by De Gruyter
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  • 4
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    X. Thomsonit von Mettweiler bei St. Wendel (1891)
    De Gruyter
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    Publication Date: 1891-01-01
    Print ISSN: 2194-4946
    Electronic ISSN: 2196-7105
    Topics: Geosciences , Physics
    Published by De Gruyter
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  • 5
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    Testing the analytical performance of handheld XRF using marine sediments of IODP Expedition 355 (2019)
    Cambridge University Press
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    Publication Date: 2019-04-04
    Description: Obtaining geochemical profiles using X-ray fluorescent (XRF) techniques has become a standard procedure in many sediment core studies. The resulting datasets are not only important tools for palaeoclimatic and palaeoceanographic reconstructions, but also for stratigraphic correlation. The International Ocean Discovery Program (IODP) has therefore recently introduced shipboard application of a handheld XRF device, making geochemical data directly available to the science party. In all XRF scanning techniques, the physical properties of wet core halves cause substantial analytical deviations. In order to obtain estimates of element concentrations (e.g. for quantitative analyses of fluxes or mass-balance calculations), a calibration of the scanning data is required. We test whether results from the handheld XRF analysis on discrete samples are suitable for calibrating scanning data. Log-ratios with Ca as a common denominator were calculated. The comparison between the handheld device and conventional measurements show that the latter provide high-quality data describing Al, Si, K, Ca, Ti, Mn, Fe, Zn, Rb and Sr content (R2 compared with conventional measurements: ln(Al/Ca) = 0.99, ln(Si/Ca) = 0.98, ln(K/Ca) = 0.99, ln(Ti/Ca) = 0.99, ln(Mn/Ca) = 0.99, ln(Fe/Ca) = 0.99, ln(Zn/Ca) = 0.99 and ln(Sr/Ca) = 0.99). Our results imply that discrete measurements using the shipboard handheld analyser are suitable for the calibration of XRF scanning data. Our test was performed on downcore sediments from IODP Expedition 355 that display a wide variety of lithologies of both terrestrial and marine origin. The implication is that our findings are valid on a general scale and that shipboard handheld XRF analysis on discrete samples should be used for calibrating XRF scanning data.
    Print ISSN: 0016-7568
    Electronic ISSN: 1469-5081
    Topics: Geosciences
    Published by Cambridge University Press
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  • 6
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    Integrating heavy-mineral, geochemical and biomarker analyses of Plio-Pleistocene sandy and silty turbidites: a novel approach for provenance studies (Indus Fan, IODP Expedition 355) (2019)
    Cambridge University Press
    Details
    Publication Date: 2019-08-14
    Description: A multidisciplinary mineralogical, geochemical and biomarker study of Indus Fan sediments cored during International Ocean Discovery Program (IODP) Expedition 355 to the Laxmi Basin was carried out to define the different compositional signatures of sand, silt and clay. Upper Pliocene – lower Pleistocene turbidites from sites U1456 and U1457 were selected as the best candidates for this study. The integrated dataset presented here was obtained by coupling traditional and innovative bulk-sediment and single-mineral techniques on the same samples. Turbiditic deposits mostly consist of medium to fine silt, including rich and diverse heavy-mineral assemblages. Such a fine grain size forced us to push the limits of high-resolution quantitative heavy-mineral analysis down to as low as 5 μm. Heavy-mineral analysis allowed us to establish a Himalayan origin of the detritus in the studied turbidites. Heavy-mineral concentrations are higher in channel-fill than in overbank deposits. Mineralogical and geochemical data concur in revealing that fast-settling ultradense minerals such as zircon are preferentially concentrated in channel-fill deposits, whereas the top of overbank deposits are notably enriched with slow-settling platy phyllosilicates. Biomarker analysis represents a most suitable complementary technique that is able to investigate the provenance signature of the finer sediment fraction, largely consisting of clay. This technique allowed us to identify a largely terrigenous origin of organic matter at Site U1456 and an open marine origin at Site U1457. The latter site lies closer to the Laxmi Ridge, where thermal maturity increases with depth to reach the early oil window (127°C at c. 320 m below the seafloor).
    Print ISSN: 0016-7568
    Electronic ISSN: 1469-5081
    Topics: Geosciences
    Published by Cambridge University Press
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