| 1. |
- Faatz, B., et al.
(författare)
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Simultaneous operation of two soft x-ray free-electron lasers driven by one linear accelerator
- 2016
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 18
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Tidskriftsartikel (refereegranskat)abstract
- Extreme-ultraviolet to x-ray free-electron lasers (FELs) in operation for scientific applications are up to now single-user facilities. While most FELs generate around 100 photon pulses per second, FLASH at DESY can deliver almost two orders of magnitude more pulses in this time span due to its superconducting accelerator technology. This makes the facility a prime candidate to realize the next step in FELs-dividing the electron pulse trains into several FEL lines and delivering photon pulses to several users at the same time. Hence, FLASH has been extended with a second undulator line and self-amplified spontaneous emission (SASE) is demonstrated in both FELs simultaneously. FLASH can now deliver MHz pulse trains to two user experiments in parallel with individually selected photon beam characteristics. First results of the capabilities of this extension are shown with emphasis on independent variation of wavelength, repetition rate, and photon pulse length.
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| 2. |
- Vlacil, AK, et al.
(författare)
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Deficiency of Nucleotide-binding oligomerization domain-containing proteins (NOD) 1 and 2 reduces atherosclerosis
- 2020
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Ingår i: Basic research in cardiology. - : Springer Science and Business Media LLC. - 1435-1803 .- 0300-8428. ; 115:4, s. 47-
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Tidskriftsartikel (refereegranskat)abstract
- Atherosclerosis is crucially fueled by inflammatory pathways including pattern recognition receptor (PRR)-related signaling of the innate immune system. Currently, the impact of the cytoplasmic PRRs nucleotide-binding oligomerization domain-containing protein (NOD) 1 and 2 is incompletely characterized. We, therefore, generated Nod1/Nod2 double knockout mice on a low-density lipoprotein receptor (Ldlr)-deficient background (= Ldlr−/−Nod1/2−/−) which were subsequently analyzed regarding experimental atherosclerosis, lipid metabolism, insulin resistance and gut microbiota composition. Compared to Ldlr−/− mice, Ldlr−/−Nod1/2−/− mice showed reduced plasma lipids and increased hepatic expression of the scavenger receptor LDL receptor-related protein 1 after feeding a high-fat diet for 12 weeks. Furthermore, intestinal cholesterol and its bacterial degradation product coprostanol were elevated in Ldlr−/−Nod1/2−/− mice, correlating with the increased abundance of Eubacterium coprostanoligenes as assessed by 3rd generation sequencing of the gut microbiota. Atherosclerotic plaques of Ldlr−/−Nod1/2−/− mice exhibited less lipid deposition and macrophage accumulation. Moreover, macrophages from Ldlr−/−Nod1/2−/− mice showed higher expression of the cholesterol efflux transporters Abca1 and Abcg1 and accordingly reduced foam cell formation. Deficiency of Nod1 and Nod2 led to reduced plaque lipid deposition and inflammatory cell infiltration in atherosclerotic plaques. This might be explained by diminished plasma lipid levels and foam cell formation due to altered expression of key regulators of the hepatic cholesterol pathway as well as differential intestinal cholesterol metabolism and microbiota composition.
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| 3. |
- Esau, Derek, et al.
(författare)
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Controlled-Atmosphere Flame Fusion Growth of Nickel Poly-oriented Spherical Single Crystals-Unraveling Decades of Impossibility
- 2020
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Ingår i: Electrocatalysis. - : SPRINGER. - 1868-2529 .- 1868-5994. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Experimental research using monocrystalline electrodes has been a hallmark of interfacial electrochemistry and electrocatalysis since 1980. However, it has been limited to mainly noble metals because of the challenges encountered when using non-noble metals. We report on the development of controlled-atmosphere flame fusion that enables the growth of spherical single crystals of non-noble metals in controlled gaseous atmosphere and without the formation of surface or bulk oxides. The set-up is used to grow nickel single crystals the structure of which is verified using Laue X-ray back-scattering and scanning electron microscopy (SEM). The equilibrium shape of the nickel single crystals calculated using Wulff construction agrees with the actual shape determined using SEM. Electrochemical measurements in aqueous NaOH solution using the monocrystalline Ni electrodes reveal cyclic voltammetry features unique to their surface structure. The methodology, transferrable to other metals, creates enormous research opportunities in interfacial electrochemistry, electrocatalysis, surface science, gas-phase catalysis, and corrosion science.
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| 4. |
- Schuett, Fabian M., et al.
(författare)
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Controlled-Atmosphere Flame Fusion Single-Crystal Growth of Non-Noble fcc, hcp, and bcc Metals Using Copper, Cobalt, and Iron
- 2020
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Ingår i: Angewandte Chemie International Edition. - : WILEY-V C H VERLAG GMBH. - 1433-7851 .- 1521-3773. ; 59:32, s. 13246-13252
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Tidskriftsartikel (refereegranskat)abstract
- The growth of noble-metal single crystals via the flame fusion method was developed in the 1980s. Since then, there have been no major advancements to the technique until the recent development of the controlled-atmosphere flame fusion (CAFF) method to grow non-noble Ni single crystals. Herein, we demonstrate the generality of this method with the first preparation of fcc Cu as well as the first hcp and bcc single crystals of Co and Fe, respectively. The high quality of the single crystals was verified using scanning electron microscopy and Laue X-ray backscattering. Based on Wulff constructions, the equilibrium shapes of the single-crystal particles were studied, confirming the symmetry of the fcc, hcp, and bcc single-crystal lattices. The low cost of the CAFF method makes all kinds of high-quality non-noble single crystals independent of their lattice accessible for use in electrocatalysis, electrochemistry, surface science, and materials science.
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| 5. |
- Smazna, Daria, et al.
(författare)
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Buckminsterfullerene hybridized zinc oxide tetrapods : defects and charge transfer induced optical and electrical response
- 2018
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 10:21, s. 10050-10062
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Tidskriftsartikel (refereegranskat)abstract
- Buckminster fullerene (C-60) based hybrid metal oxide materials are receiving considerable attention because of their excellent fundamental and applied aspects, like semiconducting, electron transfer, luminescent behaviors, etc. and this work briefly discusses the successful fabrication of C-60 decorated ZnO tetrapod materials and their detailed structure-property relationships including device sensing applications. The electron microscopy investigations indicate that a quite dense surface coverage of ZnO tetrapods with C-60 clusters is achieved. The spectroscopy studies confirmed the identification of the C-60 vibrational modes and the C-60 induced changes in the absorption and luminescence properties of the ZnO tetrapods. An increased C-60 concentration on ZnO results in steeper ZnO bandgap absorption followed by well-defined free exciton and 3.31 eV line emissions. As expected, higher amounts of C-60 increase the intensity of C-60-related visible absorption bands. Pumping the samples with photons with an energy corresponding to these absorption band maxima leads to additional emission from ZnO showing an effective charge transfer phenomenon from C-60 to the ZnO host. The density of states model obtained from DFT studies for pure and C-60 coated ZnO surfaces confirms the experimental observations. The fabricated C-60-ZnO hybrid tetrapod based micro- and nanodevices showed interesting ethanol gas sensing characteristics.
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