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Search Results: 1 - 10 of 324950 matches for " S. Diebold "
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Nucleic acids and endosomal pattern recognition: how to tell friend from foe?
Eva Brencicova,Sandra S. Diebold
Frontiers in Cellular and Infection Microbiology , 2013, DOI: 10.3389/fcimb.2013.00037
Abstract: The innate immune system has evolved endosomal and cytoplasmic receptors for the detection of viral nucleic acids as sensors for virus infection. Some of these pattern recognition receptors (PRR) detect features of viral nucleic acids that are not found in the host such as long stretches of double-stranded RNA (dsRNA) and uncapped single-stranded RNA (ssRNA) in case of Toll-like receptor (TLR) 3 and RIG-I, respectively. In contrast, TLR7/8 and TLR9 are unable to distinguish between viral and self-nucleic acids on the grounds of distinct molecular patterns. The ability of these endosomal TLR to act as PRR for viral nucleic acids seems to rely solely on the mode of access to the endolysosomal compartment in which recognition takes place. The current dogma states that self-nucleic acids do not enter the TLR-sensing compartment under normal physiological conditions. However, it is still poorly understood how dendritic cells (DC) evade activation by self-nucleic acids, in particular with regard to specific DC subsets, which are specialized in taking up material from dying cells for cross-presentation of cell-associated antigens. In this review we discuss the current understanding of how the immune system distinguishes between foreign and self-nucleic acids and point out some of the key aspects that still require further research and clarification.
Ordered Array of Single Adatoms with Remarkable Thermal Stability: Au/Fe3O4(001)
Zbyněk Novotny,Giacomo Argentero,Zhiming Wang,Michael Schmid,Ulrike Diebold,Gareth S. Parkinson
Physics , 2012, DOI: 10.1103/PhysRevLett.108.216103
Abstract: Gold deposited on the Fe$_3$O$_4$(001) surface at room temperature was studied using Scanning Tunneling Microscopy (STM) and X-ray photoelectron spectroscopy (XPS). This surface forms a ($\sqrt2 \times \sqrt2$)R45$^{\circ}$ reconstruction, where pairs of Fe and neighboring O ions are slightly displaced laterally producing undulating rows with `narrow' and `wide' hollow sites. At low coverages, single Au adatoms adsorb exclusively at the narrow sites, with no significant sintering up to annealing temperatures of 400 $^{\circ}$C. We propose the strong site preference to be related to charge and orbital ordering within the first subsurface layer of Fe$_3$O$_4$(001)-($\sqrt2 \times \sqrt2$)R45$^{\circ}$. Due to its high thermal stability, this could prove an ideal model system for probing the chemical reactivity of single atomic species.
Ordered Array of Single Au Adatoms with Remarkable Thermal Stability: Au/Fe3O4(001)
Zbyněk Novotny,Giacomo Argentero,Zhiming Wang,Michael Schmid,Ulrike Diebold,Gareth S. Parkinson
Physics , 2012, DOI: 10.1103/PhysRevLett.108.216103
Abstract: We present a Scanning Tunneling Microscopy (STM) investigation of gold deposited at the magnetite Fe3O4(001) surface at room temperature. This surface forms a reconstruction with (\surd2\times\surd2)R45{\deg} symmetry, where pairs of Fe and neighboring O ions are slightly displaced laterally, forming undulating rows with 'narrow' and 'wide' adsorption sites. At fractional monolayer coverages, single Au adatoms adsorb exclusively at the narrow sites, with no significant sintering up to annealing temperatures of 400 {\deg}C. The strong preference for this site is possibly related to charge and orbital ordering within the first subsurface layer of the reconstructed Fe3O4(001) surface. Because of their high thermal stability, the ordered Au atoms at Fe3O4(001)- (\surd2\times\surd2)R45{\deg} could provide useful for probing the chemical reactivity of single atomic species.
Soft Proton Scattering Efficiency Measurements on X-Ray Mirror Shells
S. Diebold,C. Tenzer,E. Perinati,A. Santangelo,M. Freyberg,P. Friedrich,J. Jochum
Physics , 2015, DOI: 10.1007/s10686-015-9451-4
Abstract: In-orbit experience has shown that soft protons are funneled more efficiently through focusing Wolter-type optics of X-ray observatories than simulations predicted. These protons can degrade the performance of solid-state X-ray detectors and contribute to the instrumental background. Since laboratory measurements of the scattering process are rare, an experiment for grazing angles has been set up at the accelerator facility of the University of T\"ubingen. Systematic measurements at incidence angles ranging from 0.3{\deg} to 1.2{\deg} with proton energies around 250 keV, 500 keV, and 1 MeV have been carried out. Parts of spare mirror shells of the eROSITA (extended ROentgen Survey with an Imaging Telescope Array) instrument have been used as scattering targets. This publication comprises a detailed description of the setup, the calibration and normalization methods, and the scattering efficiency and energy loss results. A comparison of the results with a theoretical scattering description and with simulations is included as well.
Antibody-Antigen-Adjuvant Conjugates Enable Co-Delivery of Antigen and Adjuvant to Dendritic Cells in Cis but Only Have Partial Targeting Specificity
Martin Kreutz, Benoit Giquel, Qin Hu, Ram Abuknesha, Satoshi Uematsu, Shizuo Akira, Frank O. Nestle, Sandra S. Diebold
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0040208
Abstract: Antibody-antigen conjugates, which promote antigen-presentation by dendritic cells (DC) by means of targeted delivery of antigen to particular DC subsets, represent a powerful vaccination approach. To ensure immunity rather than tolerance induction the co-administration of a suitable adjuvant is paramount. However, co-administration of unlinked adjuvant cannot ensure that all cells targeted by the antibody conjugates are appropriately activated. Furthermore, antigen-presenting cells (APC) that do not present the desired antigen are equally strongly activated and could prime undesired responses against self-antigens. We, therefore, were interested in exploring targeted co-delivery of antigen and adjuvant in cis in form of antibody-antigen-adjuvant conjugates for the induction of anti-tumour immunity. In this study, we report on the assembly and characterization of conjugates consisting of DEC205-specific antibody, the model antigen ovalbumin (OVA) and CpG oligodeoxynucleotides (ODN). We show that such conjugates are more potent at inducing cytotoxic T lymphocyte (CTL) responses than control conjugates mixed with soluble CpG. However, our study also reveals that the nucleic acid moiety of such antibody-antigen-adjuvant conjugates alters their binding and uptake and allows delivery of the antigen and the adjuvant to cells partially independently of DEC205. Nevertheless, antibody-antigen-adjuvant conjugates are superior to antibody-free antigen-adjuvant conjugates in priming CTL responses and efficiently induce anti-tumour immunity in the murine B16 pseudo-metastasis model. A better understanding of the role of the antibody moiety is required to inform future conjugate vaccination strategies for efficient induction of anti-tumour responses.
CO Induced Adatom Sintering in a Model Catalyst: Pd/Fe3O4
Gareth S. Parkinson,Zbynek Novotny,Giacomo Argentero,Michael Schmid,Ji?í Pavelec,Rukan Kosak,Peter Blaha,Ulrike Diebold
Physics , 2013, DOI: 10.1038/nmat3667
Abstract: The coarsening of catalytically-active metal clusters is often accelerated by the presence of gases through the formation of mobile intermediates, though the exact mechanism through which this happens is often subject to debate. We use scanning tunneling microscopy (STM) to follow the CO induced coalescence of Pd adatoms supported on the Fe3O4(001) surface at room temperature. We show that highly-mobile Pd-carbonyl species, formed via the so-called skyhook effect, are temporarily trapped at other Pd adatoms. Once these reach a critical density, clusters nucleate; subsequent coarsening occurs through cluster diffusion and coalescence. While CO increases the mobility in the Pd/Fe3O4 system, surface hydroxyls have the opposite effect. Pd atoms transported to surface OH groups are no longer susceptible to the skyhook effect and remain isolated. Following the evolution from well-dispersed metal adatoms into clusters, atom-by-atom, allows identification of the key processes that underlie gas-induced mass transport.
地球物理学报 , 1994,
Abstract: 本文利用中、美联合调查南海海洋地质项目所采集的双船地震扩展排列剖面资料,研究了南海北部陆缘的地壳结构.其特征为:从陆架到深海平原,地壳呈阶梯状减薄,地壳厚度分别为26—28km,23—24km,13—15km,以及南海洋盆中5—7km厚的洋壳,反映了地壳在新生代早期是幕式拉张的.地壳底部存在高速地壳层,地震波速度为7.1—7.4km/s.它是在地壳被拉张后,上地幔熔融物质上涌到地壳底部冷却而形成的.
Recent developments for the testing of Cherenkov Telescope Array mirrors and actuators in Tübingen
J. Dick,A. Bonardi,S. Bressel,M. Capasso,S. Diebold,F. Eisenkolb,D. Gottschall,E. Kendziorra,G. Pühlhofer,S. Renner,A. Santangelo,T. Schanz,C. Tenzer
Physics , 2015,
Abstract: The Cherenkov Telescope Array (CTA) is the next generation Cherenkov telescope facility. It will consist of a large number of segmented-mirror telescopes of three different diameters, placed in two locations, one in the northern and one in the southern hemisphere, thus covering the whole sky. The total number of mirror tiles will be on the order of 10,000, corresponding to a reflective area of ~10^4 m^2. The Institute for Astronomy and Astrophysics in T\"ubingen (IAAT) is currently developing mirror control alignment mechanics, electronics, and software optimized for the medium sized telescopes. In addition, IAAT is participating in the CTA mirror prototype testing. In this paper we present the status of the current developments, the main results of recent tests, and plans for the production phase of the mirror control system. We also briefly present the T\"ubingen facility for mirror testing.
Monitoring of In Vivo Function of Superparamagnetic Iron Oxide Labelled Murine Dendritic Cells during Anti-Tumour Vaccination
Richard Tavaré, Pervinder Sagoo, Gopal Varama, Yakup Tanriver, Alice Warely, Sandra S. Diebold, Richard Southworth, Tobias Schaeffter, Robert I. Lechler, Reza Razavi, Giovanna Lombardi, Gregory E. D. Mullen
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0019662
Abstract: Dendritic cells (DCs) generated in vitro to present tumour antigens have been injected in cancer patients to boost in vivo anti-tumour immune responses. This approach to cancer immunotherapy has had limited success. For anti-tumour therapy, delivery and subsequent migration of DCs to lymph nodes leading to effective stimulation of effector T cells is thought to be essential. The ability to non-invasively monitor the fate of adoptively transferred DCs in vivo using magnetic resonance imaging (MRI) is an important clinical tool to correlate their in vivo behavior with response to treatment. Previous reports of superparamagnetic iron oxides (SPIOs) labelling of different cell types, including DCs, have indicated varying detrimental effects on cell viability, migration, differentiation and immune function. Here we describe an optimised labelling procedure using a short incubation time and low concentration of clinically used SPIO Endorem to successfully track murine DC migration in vivo using MRI in a mouse tumour model. First, intracellular labelling of bone marrow derived DCs was monitored in vitro using electron microscopy and MRI relaxometry. Second, the in vitro characterisation of SPIO labelled DCs demonstrated that viability, phenotype and functions were comparable to unlabelled DCs. Third, ex vivo SPIO labelled DCs, when injected subcutaneously, allowed for the longitudinal monitoring by MR imaging of their migration in vivo. Fourth, the SPIO DCs induced the proliferation of adoptively transferred CD4+ T cells but, most importantly, they primed cytotoxic CD8+ T cell responses to protect against a B16-Ova tumour challenge. Finally, using anatomical information from the MR images, the immigration of DCs was confirmed by the increase in lymph node size post-DC injection. These results demonstrate that the SPIO labelling protocol developed in this study is not detrimental for DC function in vitro and in vivo has potential clinical application in monitoring therapeutic DCs in patients with cancer.
Real Space Imaging of the Verwey Transition at the (100) Surface of Magnetite
Juan de la Figuera,Zbynek Novotny,Martin Setvin,Tijiang Liu,Zhiqiang Mao,Gong Chen,Alpha T. N'Diaye,Michael Schmid,Ulrike Diebold,Andreas K. Schmid,Gareth S. Parkinson
Physics , 2013, DOI: 10.1103/PhysRevB.88.161410
Abstract: Effects of the Verwey transition on the (100) surface of magnetite were studied using scanning tunelling microscopy and spin polarized low-energy electron microsccopy. On cooling through the transition temperature Tv, the initially flat surface undergoes a roof-like distortion with a periodicity of ~0.5 um due to ferroelastic twinning within monoclinic domains of the low-temperature monoclinic structure. The monoclinic c axis orients in the surface plane, along the [001]c directions. At the atomic scale, the charge-ordered sqrt2xsqrt2R45 reconstruction of the (100) surface is unperturbed by the bulk transition, and is continuous over the twin boundaries. Time resolved low-energy electron microscopy movies reveal the structural transition to be first-order at the surface, indicating that the bulk transition is not an extension of the Verwey-like sqrt2xsqrt2R45 reconstruction. Although conceptually similar, the charge-ordered phases of the (100) surface and sub-Tv bulk of magnetite are unrelated phenomena.
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