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21.
Bernd Schaldach Barbara Grotemeyer Jürgen Grotemeyer Hans-Friedrich Grützmacher 《Journal of mass spectrometry : JMS》1981,16(9):410-415
meta and para substituted benzalacetones lose the substituents after electron impact in a multi-step intramolecular aromatic substitution. The differences in the relative abundances of the benzopyrylium ions thus formed are not determined by the activation energies for the substituent losses but depend on a delicate balance between the thermodynamic stability of the intermediates involved and the rates of several H-shifts within the intermediates (kinetic stability). The consequences for the analytical utility of intramolecular aromatic substitution are discussed briefly. 相似文献
22.
We analyze and demonstrate the feasibility and superiority of linear optical single-qubit fingerprinting over its classical counterpart. For one-qubit fingerprinting of two-bit messages, we prepare "tetrahedral" qubit states experimentally and show that they meet the requirements for quantum fingerprinting to exceed the classical capability. We prove that shared entanglement permits 100% reliable quantum fingerprinting, which will outperform classical fingerprinting even with arbitrary amounts of shared randomness. 相似文献
23.
24.
Christian Fischer Karl-Peter Fritz Peter Eberhard Heinz Kück 《Archive of Applied Mechanics (Ingenieur Archiv)》2013,83(8):1171-1192
New concepts for an impact actuated micro shift valve are presented which are useful, e.g. as implant for the hydrocephalus disease. Such an implant must fulfil requirements, such as using biocompatible materials, a separation of the actuator from the fluid, MRT safety and low-energy consumption in order to allow a battery-powered system. The concepts are based on the impacts that transmit an impulse into the interior of the valve through the casing, switching the valve. In order to predict the energy transmitted into the valve, an elastic multibody model is created, verified with full finite element simulations and experiments on scaled-up models. Using this model, the most important effects and parameters are discussed. Also, fluid effects are included into the elastic multibody model for a qualitative assessment of its influence on the efficiency. The simulations are compared to experiments performed with a scaled model for two different cases. Two designs of a shift valve based on impact actuation are built as prototypes and tested. 相似文献
25.
Nils Hellwig Alexander Thrun Tassilo Muskat Jürgen Grotemeyer 《Analytical and bioanalytical chemistry》2009,395(8):2457-2463
Ionic liquid matrices are a new class of matrices used in MALDI mass spectrometry. The ablation process of several ionic liquid
matrices was studied by determining the velocity distribution of ablated neutral matrix molecules. This was done by a postionization
approach, where the neutrals were ionized in the ablation plume by a second laser pulse. It was found that a second, time-delayed
ablation event occurs consisting completely of neutral molecules. To explain this, the reflected-shockwave model is used,
which assumes that the shockwave emerging from the laser ablation is reflected at the sample holder surface. When the shockwave
arrives at the sample surface it causes a second ablation. 相似文献
26.
Liebig T Lüning U Grotemeyer J 《European journal of mass spectrometry (Chichester, England)》2006,12(2):117-120
For the first time the formation of supramolecular clusters between concave pyridines and different carbohydrates could be observed in the gas phase. The different clusters have been investigated by means of laser desorption into a supersonic beam followed by resonant multi photon excitation yielding mass spectra with high intensity of the different cluster. These preliminary results open a way for the investigations of the hydrogen bonds in these compounds. 相似文献
27.
K. P. Grotemeyer 《Archiv der Mathematik》1958,9(1-2):117-122
Ohne ZusammenfassungHerrnHellmuth Kneser zum 60. Geburtstag am 16. April 1958 gewidmet 相似文献
28.
Resonance enhanced multi-photon ionization-reflectron time of flight mass spectrometry is the analytical method of choice to observe hydrogen bonded supramolecules in the gas phase when protonation of basic centers competes with cluster formation. 相似文献
29.
K. P. Grotemeyer 《Mathematische Zeitschrift》1955,62(1):17-22
Ohne ZusammenfassungHerrnWilhelm Süss zum 60. Geburtstag am 7. März 1955 gewidmet. 相似文献
30.
Adedamola A. Opalade Elizabeth N. Grotemeyer Timothy A. Jackson 《Molecules (Basel, Switzerland)》2021,26(23)
Manganese lipoxygenase (MnLOX) is an enzyme that converts polyunsaturated fatty acids to alkyl hydroperoxides. In proposed mechanisms for this enzyme, the transfer of a hydrogen atom from a substrate C-H bond to an active-site MnIII-hydroxo center initiates substrate oxidation. In some proposed mechanisms, the active-site MnIII-hydroxo complex is regenerated by the reaction of a MnIII-alkylperoxo intermediate with water by a ligand substitution reaction. In a recent study, we described a pair of MnIII-hydroxo and MnIII-alkylperoxo complexes supported by the same amide-containing pentadentate ligand (6Medpaq). In this present work, we describe the reaction of the MnIII-hydroxo unit in C-H and O-H bond oxidation processes, thus mimicking one of the elementary reactions of the MnLOX enzyme. An analysis of kinetic data shows that the MnIII-hydroxo complex [MnIII(OH)(6Medpaq)]+ oxidizes TEMPOH (2,2′-6,6′-tetramethylpiperidine-1-ol) faster than the majority of previously reported MnIII-hydroxo complexes. Using a combination of cyclic voltammetry and electronic structure computations, we demonstrate that the weak MnIII-N(pyridine) bonds lead to a higher MnIII/II reduction potential, increasing the driving force for substrate oxidation reactions and accounting for the faster reaction rate. In addition, we demonstrate that the MnIII-alkylperoxo complex [MnIII(OOtBu)(6Medpaq)]+ reacts with water to obtain the corresponding MnIII-hydroxo species, thus mimicking the ligand substitution step proposed for MnLOX. 相似文献