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101.
M. Sbetti E. Moser M. Montagna M. Ferrari S. Chaussedent M. Bettinelli 《Journal of Non》1997,220(2-3):217-221
In this work we report on the temperature depedence of the homogeneous line width (Γh) in 4ZnO · 3B2O3:Eu3+ glass in the region between 30 K and room temperature. The time resolved resonant fluorescence line narrowing technique was applied to the 7F0 ↔ 5D0 transition of Eu3+. We obtain that Γh follows the commonly found behaviour T2 in the whole range of temperature (30–300 K). The Γh is comparable to that measured in borate glasses with a small amount of network modifier. This result, together with a linear increase of Γh with the excitation energy within the inhomogeneous profile, is indicative of a specific local environment around the Eu3+ ion in the zinc borate glass. 相似文献
102.
103.
The use of CE as a tool to conduct immunoassays has been an area of increasing interest over the last decade. This approach combines the efficiency, small sample requirements, and relatively high speed of CE with the selectivity of antibodies as binding agents. This review examines the various assay formats and detection modes that have been reported for these assays, along with some representative applications. Most CE immunoassays in the past have employed homogeneous methods in which the sample and reagents are allowed to react in solution. These homogeneous methods have been conducted as both competitive binding immunoassays and as noncompetitive binding immunoassays. Fluorescent labels are most commonly used for detection in these assays, but enzyme labels have also been utilized for such work. Some additional work has been performed in CE immunoassays with heterogeneous methods in which either antibodies or an analog of the analyte is immobilized to a solid support. These heterogeneous methods can be used for the selective isolation of analytes prior to their separation by CE or to remove a given species from a sample/reagent mixture prior to analysis by CE. These CE immunoassays can be used with a variety of detection modes, such as fluorescence, UV/Vis absorbance, chemiluminescence, electrochemical measurements, MS, and surface plasmon resonance. 相似文献
104.
Daniel Moser Dr. Kalipada Jana Prof. Dr. Christof Sparr 《Angewandte Chemie (International ed. in English)》2023,62(39):e202309053
Herein, we describe the feasibility of atroposelective PIII/PV=O redox organocatalysis by the Staudinger–aza-Wittig reaction. The formation of isoquinoline heterocycles thereby enables the synthesis of a broad range of valuable atropisomers under mild conditions with enantioselectivities of up to 98 : 2 e.r. Readily prepared azido cinnamate substrates convert in high yield with stereocontrol by a chiral phosphine catalyst, which is regenerated using a silane reductant under Brønsted acid co-catalysis. The reaction provides access to diversified aryl isoquinolines, as well as benzoisoquinoline and naphthyridine atropisomers. The products are expeditiously transformed into N-oxides, naphthol and triaryl phosphine variants of prevalent catalysts and ligands. With dinitrogen release and aromatization as ideal driving forces, it is anticipated that atroposelective redox organocatalysis provides access to a multitude of aromatic heterocycles with precise control over their configuration. 相似文献
105.
J.D. Pedarnig J. Heitz T. Stehrer B. Praher R. Viskup K. Siraj A. Moser A. Vlad M.A. Bodea D. Bäuerle N. Hari Babu D.A. Cardwell 《Spectrochimica Acta Part B: Atomic Spectroscopy》2008
Multi-component oxide ceramics and epitaxial oxide thin films are analyzed by laser-induced breakdown spectroscopy (LIBS). Furthermore, pulsed-laser deposition (PLD) of thin films is investigated by long-term monitoring of the optical plasma emission. Both nano-composite high-temperature superconductors (HTS) consisting of YBa2Cu3O7 − δ bulk and Y2Ba4MCuOx (M-2411, M = Ag, Nb) nano-particles, and semiconducting ZnO doped with Aluminum and Lithium are ablated by nano-second laser pulses. The plasma emission is recorded using grating spectrometers with intensified gated detectors. The LIBS signals of nano-particles correlate with the nominal content of the M-2411 phase (0–15 mol%) and reveal a strong signal of Ytterbium impurity (3–35 ppm). In situ monitoring of the PLD process shows element signals that are stable for more than 10,000 laser pulses for both HTS and ZnO ceramics. The relative concentration of elements in thin films and ceramics as determined by LIBS is almost the same. 相似文献
106.
G.J. Spühler T. Südmeyer R. Paschotta M. Moser K.J. Weingarten U. Keller 《Applied physics. B, Lasers and optics》2000,71(1):19-25
We discuss power scaling of passively mode-locked lasers using multiple laser heads in the resonator. We experimentally compared two different approaches for the cavity design, both using three side-pumped Nd:YAG laser heads. We obtained a record-high average output power of up to 27 W with close to diffraction-limited beam quality, a pulse duration of 19 ps, a pulse energy of 0.5 7J, and 23 kW peak power. Single-pass second-harmonic generation in a 10-mm-long LBO crystal yields 16.2 W of 532-nm radiation. 相似文献
107.
Walter Mühlecker Bernhard Krutler Daniel Moser Philippe Matile Stefan Hrtensteiner 《Helvetica chimica acta》2000,83(1):278-286
The primary fluorescent chlorophyll catabolite 1 (Ca‐FCC‐2) from sweet pepper (Capsicum annuum) has similar optical properties, but is slightly less polar than the primary FCC (pFCC; 2 ) from senescent cotyledons of oilseed rape (Brassica napus). Ca‐FCC‐2 was prepared from pheophorbide a using an enzyme extract from ripe C. annuum chromoplasts. The catabolite Ca‐FCC‐2 ( 1 ) could be determined from fast‐atom‐bombardment (FAB) mass spectra to be an isomer of pFCC ( 2 ). The constitution of Ca‐FCC‐2 was determined by homo‐ and heteronuclear magnetic‐resonance experiments and was found to be identical to that of pFCC. Further 2D‐homonuclear spectra of Ca‐FCC‐2 revealed it to differ from pFCC by the configuration at the methine atom C(1), whose configuration results from the action of red chlorophyll catabolite reductase (RCCR). The occurrence of two primary FCCs that are epimeric at C(1) provides a structural basis for the recent observation of two types of RCCRs among higher plants. 相似文献
108.
Tl2CuAsO4 – an Intermediate Phase in the Oxidation of Tl/Cu/As Alloys with Oxygen Waxy, honey-jellow single crystals of the new compound Tl2CuAsO4 (monoclinic, P21/c, a = 860.1(1) pm, b = 533.94(7) pm, c = 1200.1(2) pm, β = 98.10(1)°, Z = 4) were prepared as an intermediate product of the oxidation process in the reaction of Tl/Cu/As-alloys with oxygen. Their structure was determined from IPDS data (w2R = 0.071 for 1271 F2 values and 74 parameters). The structure contains an isolated [Cu2As2O8]4– group consisting of two AsO4-tetrahedra connected by two Cu+ ions with an approximately linear O–Cu–O coordination. The [Cu2As2O8]4– groups are linked to a threedimensional framework by thallium(I) ions which show an hemispheric coordination sphere of oxygen ions indicating the stereochemical activity of the Tl+ lone pair. 相似文献
109.
David Moser 《Journal of Graph Theory》1997,24(1):33-43
The star-chromatic number of a graph, a parameter introduced by Vince, is a natural generalization of the chromatic number of a graph. Here we construct planar graphs with star-chromatic number r, where r is any rational number between 2 and 3, partially answering a question of Vince. © 1997 John Wiley & Sons, Inc. 相似文献
110.
We propose a method to design pulses in a resonant three-level system to enhance the robustness of non-adiabatic geometric gate operations. By optimizing the shape of the pulse envelope, we show that the gate operations are more robust against frequency detuning than they are with Gaussian and square pulses. Our method provides a way to design pulses that can be employed in a system where robustness against frequency variations or inhomogeneous broadening is required, and may be extended to ensure robustness against other physical imperfections such as intensity fluctuations and random noises. 相似文献