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Linker aggregation engineering of TADF materials to tune carrierbalance for highly efﬁcient organic LEDs with long operationallifetime

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Aggregate 2024年第5期5卷 385-393页

作者： Zhen Zhang Rongrong Xia Ke Wang Youjun Wu Panpan Zang Xuemin Gan Zhangcheng Liao Bin Wei Peng Wu stefan bräse Zixing Wang Key Laboratory of Advanced Display and System Applications Ministry of EducationShanghai UniversityShanghaiChina Institute of Organic Chemistry Karlsruhe Institute of Technology(KIT)KarlsruheGermany Institute of Biological and Chemical Systems-Functional Molecular Systems(IBCS-FMS) Karlsruhe Institute of Technology(KIT)KarlsruheGermany

Thermally activated delayedﬂuorescence(TADF)molecules are regarded as promis-ing materials for realizing high-performance organic light-emitting diodes(OLEDs).The connecting groups between donor(D)and acceptor(A)units in D–A type TADF molecules could affect the charge transfer and luminescence performance of TADF materials in aggregated *** this work,we design and synthesize four TADF molecules using planar and twisted linkers to connect the aza-azulene donor(D)and triazine acceptor(A).Compared with planar linkers,the twisted ones(Az-NP-T and Az-NN-T)can enhance A–A aggregation interaction between adjacent molecules to balance hole and electron *** a result,highly efﬁcient and stable deep-red top-emission OLEDs with a high electroluminescence efﬁciency of 57.3%and an impressive long operational lifetime(LT_(95)∼30,000 h,initial luminance of 1000 cd m^(-2))are *** study provides a new strategy for designing more efﬁ-cient and stable electroluminescent devices through linker aggregation engineering in donor–acceptor molecules.

关键词： acceptor stacking balanced carrier transfer host materials long device lifetime thermally activated delayedﬂuorescence

Modulation of the Nogo signaling pathway to overcome amyloid-β-mediated neurite inhibition in human pluripotent stem cell-derived neurites

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Neural Regeneration Research 2025年第9期20卷 2645-2654页

作者： Kirsty Goncalves stefan Przyborski Department of Biosciences Durham UniversityDurhamUK Reprocell Europe Ltd. GlasgowUK

Neuronal cell death and the loss of connectivity are two of the primary pathological mechanisms underlying Alzheimer's *** accumulation of amyloid-βpeptides,a key hallmark of Alzheimer's disease,is believed to induce neuritic abnormalities,including reduced growth,extension,and abnormal growth cone morphology,all of which contribute to decreased ***,the precise cellular and molecular mechanisms governing this response remain *** this study,we used an innovative approach to demonstrate the effect of amyloid-βon neurite dynamics in both two-dimensional and three-dimensional cultu re systems,in order to provide more physiologically relevant culture *** utilized various methodologies,including the addition of exogenous amyloid-βpeptides to the culture medium,growth substrate coating,and the utilization of human-induced pluripotent stem cell technology,to investigate the effect of endogenous amyloid-βsecretion on neurite outgrowth,thus paving the way for potential future applications in personalized ***,we also explore the involvement of the Nogo signaling cascade in amyloid-β-induced neurite *** demonstrate that inhibition of downstream ROCK and RhoA components of the Nogo signaling pathway,achieved through modulation with Y-27632(a ROCK inhibitor)and Ibuprofen(a Rho A inhibitor),respectively,can restore and even enhance neuronal connectivity in the presence of amyloid-β.In summary,this study not only presents a novel culture approach that offers insights into the biological process of neurite growth and inhibition,but also proposes a specific mechanism for reduced neural connectivity in the presence of amyloid-βpeptides,along with potential intervention points to restore neurite ***,we aim to establish a culture system that has the potential to serve as an assay for measuring preclinical,predictive outcomes of drugs and their ability to promote neurite outgrowth,both generally and in a patie

关键词： Alzheimer's disease induced pluripotent stem cell neurite outgrowth neuron Nogo Rho A ROCK stem cell three-dimensional culture

Lensless diffractive imaging with ultra-broadbandtable-top sources: from infrared to extreme-ultravioletwavelengths

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Light(Science & Applications) 2014年第1期3卷 274-281页

作者： stefan Witte Vasco T Tenner Daniel WE Noom Kjeld se Eikema LaserLaB Amsterdam VU University Amsterdam1081 HV AmsterdamThe Netherlands Present address:Huygens-Kamerlingh Onnes Laboratorium Universiteit Leiden2333 CA LeidenThe Netherlands

Lensless imaging is an approach to microscopy in which a high-resolution image of an object is reconstructed from one or more measured diffraction patterns,providing a solution in situations where the use of imaging optics is not ***,current lensless imaging methods are typically limited by the need for a light source with a narrow,stable and accurately known *** have developed a general approach to lensless imaging without spectral bandwidth limitations or sample *** use two time-delayed coherent light pulses and show that scanning the pulse-to-pulse time delay allows the reconstruction of diffraction-limited images for all the spectral components in the *** addition,we introduce an iterative phase retrieval algorithm that uses these spectrally resolved Fresnel diffraction patterns to obtain high-resolution images of complex extended *** demonstrate this two-pulse imaging method with octave-spanning visible light sources,in both transmission and reflection geometries,and with broadband extreme-ultraviolet radiation from a high-harmonic generation *** approach enables effective use of low-flux ultra-broadband sources,such as table-top high-harmonic generation systems,for high-resolution imaging.

关键词： coherent diffractive imaging extreme ultraviolet Fourier transform spectroscopy high-harmonic generation lensless imaging

Cytokinin levels and signaling respond to wounding and the perception of herbivore elicitors in Nicotiana attenuata

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Journal of Integrative Plant Biology 2015年第2期57卷 198-212页

作者： Martin Sch?fer Ivan D. Meza-Canales Aura Navarro-Quezada Christoph brütting Radomira Vanková Ian T. Baldwin stefan Meldau Department of Molecular Ecology Max Planck Institute for Chemical Ecology Laboratory of Hormonal Regulations in Plants Institute of Experimental Botany AS CR German Centre for integrative Biodiversity Research (i Div)

Nearly half a century ago insect herbivores were found to induce the formation of green islands by manipulating cytokinin （CK） levels. However, the response of the CK pathway to attack by chewing insect herbivores remains unclear. Here, we characterize the CK pathway of Nicotiana attenuata （Torr. ex S. Wats.） and its response to wounding and perception of herbivoreassociated molecular patterns （HAMPs）. We identified 44 genes involved in CK biosynthesis, inactivation, degradation, and signaling. Leaf wounding rapidly induced transcriptional changes in multiple genes throughout the pathway, as well as in the levels of CKs, including isopentenyladenosine and cis-zeatin riboside; perception of HAMPs present in the oral secretions （OS） of the specialist herbivore Manduca sexta amplified these responses. The jasmonate pathway, which triggers many herbivore-induced processes, was not required for these HAMP-triggered changes, but rather suppressed the CK responses. Interestingly CK pathway changes were observed also in systemic leaves in response to wounding and OS application indicating a role of CKs in mediating long distance systemic processes in response to herbivory. Since wounding and grasshopper OS elicited similar accumulations of CKs in Arabidopsis thaliana L., we propose that CKs are integral components of wounding and HAMP-triggered responses in many plant species.

关键词： Arabidopsis thaliana cytokinin herbivore-associated molecular patterns herbivory insect jasmonic acid Manduca sexta Nicotiana attenuata wounding

Generalized Sampling in Shift Invariant Spaces with Frames

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Acta Mathematica Sinica,English series 2012年第9期28卷 1823-1844页

作者： stefan ERICSSON Department of Engineering Sciences and Mathematics Lule University of Technology

Generalized sampling in a shift invariant subspace V of L2（R） is considered. A function f in V is processed with different filters Lm and then one tries to reconstruct f from the samples L^mf（j＇k）. We develop a theory of how to do this in the case when V possesses a shift invariant frame. Special attention is paid to the question： How to obtain dual frames with compact support？

关键词： Generalized sampling frames Riesz basis reproducing kernel shift invariant spaces

Constitutive relations for the shear band evolution in granular matter under large strain

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Particuology 2008年第6期6卷 501-505页

作者： stefan Luding Multi Scale Mechanics TS CTW UTwente P.O. Box 217 7500 AE Enschede Netherlands

A so-called ＂split-bottom ring shear cell＂ leads to wide shear bands under slow, quasi-static deformation. Unlike normal cylindrical Couette shear cells or rheometers, the bottom plate is split such that the outer part of it can move with the outer wall, while the other part （inner disk） is immobile. From discrete element simulations （DEM）, several continuum fields like the density, velocity, deformation gradient and stress are computed and evaluated with the goal to formulate objective constitutive relations for the powder flow behavior. From a single simulation, by applying time- and （local） space-averaging, a non-linear yield surface is obtained with peculiar stress dependence. The anisotropy is always smaller than the macroscopic friction coefficient. However, the lower bound of anisotropy increases with the strain rate, approaching the maximum according to a stretched exponential with a specific rate that is consistent with a shear path of about one particle diameter.

关键词： Ring shear cell Shear bands DEM simulation Micro-macro transition Objective constitutive relations Yield stress fluid

Significance of scintigraphy for the localisation of obscure gastrointestinal bleedings

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World Journal of Gastroenterology 2008年第32期14卷 5015-5019页

作者： Tanja brünnler Frank Klebl Sascha Mundorff Christoph Eilles Michael Reng Hans von Korn Jürgen Schlmerich Julia Langgartner stefan Grüne Department of Internal Medicine I University of Regensburg Department of Surgery Hospital Neumarkt Department of Nuclear Medicine University of Regensburg Department of Internal Medicine Hospital Bogen Department of Internal Medicine II Hospital Hetzelstift

AIM： To determine the role of scintigraphy in patients with gastrointestinal （GI） bleeding of unknown Iocalisation. METHODS： We performed retrospective analyses on 92 patients receiving scintigraphies from 1993 to 2000 in the University of Regensburg hospital, which were done for Iocalisation of GI bleeding as a diagnostic step after an unsuccessful endoscopy. In addition to the scintigraphies, further diagnostic steps such as endoscopy, angiography or operations were performed. In some of the scintigraphies with negative results, a provocation test for bleeding with heparinisation was carried out. RESULTS： 73% of all scintigraphies showed a positive result. In 4.5% of the positive results, the source was located in the stomach, in 37% the source was the small bowel, in 25% the source was the right colon, in 4.5% the source was the left colon, and in 20% no clear Iocalisation was possible. Only 4% of all scintigraphies were false positive. A reliable positive scintigraphy was independent of the age of the examined patient. A provocation test for bleeding with heparin resulted in an additional 46% of positive scintigraphies with a reliable Iocalisation in primary negative scintigraphies. CONCLUSION- Our results show that scintigraphy and scintigraphy with heparin provocation tests are reliable procedures. They enable a reliable Iocalisation in about half of the obscure GI-bleeding cases. Scintigraphy is superior to angiography in locating a bleeding. It is shown that even in the age of video capsule endoscopy and double-balloon enteroscopy, scintigraphy provides a reliable and directed localization of GI bleeding and offers carefully targeted guidance for other procedures.

关键词： Gastrointestinal bleeding Scintigraphy Localisation Angiography

Influence of sample preparation on nanoindentation results of twinninginduced plasticity steel

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International Journal of Minerals,Metallurgy and Materials 2021年第5期28卷 877-887页

作者： Jiali Zhang stefan Zaefferer Institute for Materials Applications in Mechanical Engineering RWTH Aachen UniversityAachen 52062Germany Max-Planck-Institut für Eisenforschung Düsseldorf 40237Germany

Nanoindentation is an attractive characterization technique,as it not only measures the local properties of a material but also facilitates understanding of deformation mechanisms at submicron ***,because of the complex stress-strain field and the small scale of the deformation under the nanoindenter,the results can be easily influenced by artifacts induced during sample *** this work,a systematic study was conducted to better understand the influence of sample preparation methods on the nanoindentation results of ductile *** experiments were conducted on a steel(Fe-22Mn-0.65C,wt%)with twinning-induced plasticity(TWIP),which was selected for its large grain size and sensitivity to different surface preparation *** grouping the results obtained from each nanoindent,chemical polishing was found to be the best sample preparation method with respect to the resulting mechanical properties of the *** contrast,the presence of a deformation layer left by mechanical polishing and surface damage induced by focused ion beam(FIB)scanning were confirmed by the dislocation-nucleation-induced pop-in events of nanoindentation.

关键词： TWIP steels nanoindentation mechanical polishing chemical polishing pop-in

Experimental investigation on slip conditions during thread rolling with flat dies

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Friction 2024年第1期12卷 136-143页

作者： stefan VOLZ Peter GROCHE Institute for Production Engineering and Forming Machines Technical University DarmstadtOtto-Berndt Straße 2Darmstadt 64287Germany

The process design of flat die rolling operations can be a tedious and costly process due to the challenges posed by small process *** this work,an effort is made to closely investigate and understand the process limits caused by excessive slippage of the *** measurements are carried out to capture the characteristics of excessive slippage and the influence of the stroke rate and the tribological system on this process *** differences in slippage were observed,depending on the tribological *** systems with polymer based lubricants showed excessive slippage at low stroke rates,systems using oil or no lubricant endured higher stroke rates before process limits were *** optical measurements revealed three major forms of slippage:successful rolling without slippage,failure due to excessive slippage at process start,and failure due to excessive slippage at around one workpiece rotation.

关键词： rolling incremental forming thread rolling slippage profile rolling