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LaForge AC, Stumpf V, Gokhberg K, von Vangerow J, Stienkemeier F, Kryzhevoi NV, O'Keeffe P, Ciavardini A, Krishnan SR, Coreno M, Prince KC, Richter R, Moshammer R, Pfeifer T, Cederbaum LS, Mudrich M. Enhanced Ionization of Embedded Clusters by Electron-Transfer-Mediated Decay in Helium Nanodroplets. PHYSICAL REVIEW LETTERS 2016; 116:203001. [PMID: 27258866 DOI: 10.1103/physrevlett.116.203001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Indexed: 06/05/2023]
Abstract
We report the observation of electron-transfer-mediated decay (ETMD) involving magnesium (Mg) clusters embedded in helium (He) nanodroplets. ETMD is initiated by the ionization of He followed by removal of two electrons from the Mg clusters of which one is transferred to the He ion while the other electron is emitted into the continuum. The process is shown to be the dominant ionization mechanism for embedded clusters for photon energies above the ionization potential of He. For Mg clusters larger than five atoms we observe stable doubly ionized clusters. Thus, ETMD provides an efficient pathway to the formation of doubly ionized cold species in doped nanodroplets.
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Schmöger L, Schwarz M, Baumann TM, Versolato OO, Piest B, Pfeifer T, Ullrich J, Schmidt PO, López-Urrutia JRC. Deceleration, precooling, and multi-pass stopping of highly charged ions in Be⁺ Coulomb crystals. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2015; 86:103111. [PMID: 26520944 DOI: 10.1063/1.4934245] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Preparing highly charged ions (HCIs) in a cold and strongly localized state is of particular interest for frequency metrology and tests of possible spatial and temporal variations of the fine structure constant. Our versatile preparation technique is based on the generic modular combination of a pulsed ion source with a cryogenic linear Paul trap. Both instruments are connected by a compact beamline with deceleration and precooling properties. We present its design and commissioning experiments regarding these two functionalities. A pulsed buncher tube allows for the deceleration and longitudinal phase-space compression of the ion pulses. External injection of slow HCIs, specifically Ar(13+), into the linear Paul trap and their subsequent retrapping in the absence of sympathetic cooling is demonstrated. The latter proved to be a necessary prerequisite for the multi-pass stopping of HCIs in continuously laser-cooled Be(+) Coulomb crystals.
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Heeg KP, Ott C, Schumacher D, Wille HC, Röhlsberger R, Pfeifer T, Evers J. Interferometric phase detection at x-ray energies via Fano resonance control. PHYSICAL REVIEW LETTERS 2015; 114:207401. [PMID: 26047250 DOI: 10.1103/physrevlett.114.207401] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Indexed: 06/04/2023]
Abstract
Modern x-ray light sources promise access to structure and dynamics of matter in largely unexplored spectral regions. However, the desired information is encoded in the light intensity and phase, whereas detectors register only the intensity. This phase problem is ubiquitous in crystallography and imaging and impedes the exploration of quantum effects at x-ray energies. Here, we demonstrate phase-sensitive measurements characterizing the quantum state of a nuclear two-level system at hard x-ray energies. The nuclei are initially prepared in a superposition state. Subsequently, the relative phase of this superposition is interferometrically reconstructed from the emitted x rays. Our results form a first step towards x-ray quantum state tomography and provide new avenues for structure determination and precision metrology via x-ray Fano interference.
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Woltsche N, Pfeifer T, Petru E, Haas J, Pickel H. Ab welcher Tumorgröße ist beim operablen Zervixkarzinom parametraner Befall zu erwarten? Geburtshilfe Frauenheilkd 2015. [DOI: 10.1055/s-0035-1548627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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30
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Schnorr K, Senftleben A, Schmid G, Rudenko A, Kurka M, Meyer K, Foucar L, Kübel M, Kling MF, Jiang YH, Düsterer S, Treusch R, Schröter CD, Ullrich J, Pfeifer T, Moshammer R. Multiple ionization and fragmentation dynamics of molecular iodine studied in IR-XUV pump-probe experiments. Faraday Discuss 2014; 171:41-56. [PMID: 25415043 DOI: 10.1039/c4fd00031e] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The ionization and fragmentation dynamics of iodine molecules (I(2)) are traced using very intense (∼10(14) W cm(-2)) ultra-short (∼60 fs) light pulses with 87 eV photons of the Free-electron LASer at Hamburg (FLASH) in combination with a synchronized femtosecond optical laser. Within a pump-probe scheme the IR pulse initiates a molecular fragmentation and then, after an adjustable time delay, the system is exposed to an intense FEL pulse. This way we follow the creation of highly-charged molecular fragments as a function of time, and probe the dynamics of multi-photon absorption during the transition from a molecule to individual atoms.
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31
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Fahrmayr C, König J, Auge D, Mieth M, Münch K, Segrestaa J, Pfeifer T, Treiber A, Fromm M. Phase I and II metabolism and MRP2-mediated export of bosentan in a MDCKII-OATP1B1-CYP3A4-UGT1A1-MRP2 quadruple-transfected cell line. Br J Pharmacol 2014; 169:21-33. [PMID: 23387445 DOI: 10.1111/bph.12126] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 12/05/2012] [Accepted: 12/16/2012] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Hepatic uptake (e.g. by OATP1B1), phase I and II metabolism (e.g. by CYP3A4, UGT1A1) and subsequent biliary excretion (e.g. by MRP2) are key determinants for the pharmacokinetics of numerous drugs. However, stably transfected cell models for the simultaneous investigation of transport and phase I and II metabolism of drugs are lacking. EXPERIMENTAL APPROACH A newly established quadruple-transfected MDCKII-OATP1B1-CYP3A4-UGT1A1-MRP2 cell line was used to investigate metabolism and transcellular transport of the endothelin receptor antagonist bosentan. KEY RESULTS Intracellular accumulation of bosentan equivalents (i.e. parent compound and metabolites) was significantly lower in all cell lines expressing MRP2 compared to cell lines lacking this transporter (P < 0.001). Accordingly, considerably higher amounts of bosentan equivalents were detectable in the apical compartments of cell lines with MRP2 expression (P < 0.001). HPLC and LC-MS measurements revealed that mainly unchanged bosentan accumulated in intracellular and apical compartments. Furthermore, the phase I metabolites Ro 48-5033 and Ro 47-8634 were detected intracellularly in cell lines expressing CYP3A4. Additionally, a direct glucuronide of bosentan could be identified intracellularly in cell lines expressing UGT1A1 and in the apical compartments of cell lines expressing UGT1A1 and MRP2. CONCLUSIONS AND IMPLICATIONS These in vitro data indicate that bosentan is a substrate of UGT1A1. Moreover, the efflux transporter MRP2 mediates export of bosentan and most likely also of bosentan glucuronide in the cell system. Taken together, cell lines simultaneously expressing transport proteins and metabolizing enzymes represent additional useful tools for the investigation of the interplay of transport and metabolism of drugs.
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Schnorr K, Senftleben A, Kurka M, Rudenko A, Schmid G, Pfeifer T, Meyer K, Kübel M, Kling MF, Jiang YH, Treusch R, Düsterer S, Siemer B, Wöstmann M, Zacharias H, Mitzner R, Zouros TJM, Ullrich J, Schröter CD, Moshammer R. Electron rearrangement dynamics in dissociating I(2)^(n+) molecules accessed by extreme ultraviolet pump-probe experiments. PHYSICAL REVIEW LETTERS 2014; 113:073001. [PMID: 25170702 DOI: 10.1103/physrevlett.113.073001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Indexed: 05/11/2023]
Abstract
The charge rearrangement in dissociating I_{2}^{n+} molecules is measured as a function of the internuclear distance R using extreme ultraviolet pulses delivered by the free-electron laser in Hamburg. Within an extreme ultraviolet pump-probe scheme, the first pulse initiates dissociation by multiply ionizing I_{2}, and the delayed probe pulse further ionizes one of the two fragments at a given time, thus triggering charge rearrangement at a well-defined R. The electron transfer between the fragments is monitored by analyzing the delay-dependent ion kinetic energies and charge states. The experimental results are in very good agreement with predictions of the classical over-the-barrier model demonstrating its validity in a thus far unexplored quasimolecular regime relevant for free-electron laser, plasma, and chemistry applications.
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Schnorr K, Senftleben A, Kurka M, Rudenko A, Foucar L, Schmid G, Broska A, Pfeifer T, Meyer K, Anielski D, Boll R, Rolles D, Kübel M, Kling MF, Jiang YH, Mondal S, Tachibana T, Ueda K, Marchenko T, Simon M, Brenner G, Treusch R, Scheit S, Averbukh V, Ullrich J, Schröter CD, Moshammer R. Time-resolved measurement of interatomic coulombic decay in Ne2. PHYSICAL REVIEW LETTERS 2013; 111:093402. [PMID: 24033032 DOI: 10.1103/physrevlett.111.093402] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Indexed: 06/02/2023]
Abstract
The lifetime of interatomic Coulombic decay (ICD) [L. S. Cederbaum et al., Phys. Rev. Lett. 79, 4778 (1997)] in Ne2 is determined via an extreme ultraviolet pump-probe experiment at the Free-Electron Laser in Hamburg. The pump pulse creates a 2s inner-shell vacancy in one of the two Ne atoms, whereupon the ionized dimer undergoes ICD resulting in a repulsive Ne+(2p(-1))-Ne+(2p(-1)) state, which is probed with a second pulse, removing a further electron. The yield of coincident Ne+-Ne2+ pairs is recorded as a function of the pump-probe delay, allowing us to deduce the ICD lifetime of the Ne2(+)(2s(-1)) state to be (150±50) fs, in agreement with quantum calculations.
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34
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Meyer K, Ott C, Raith P, Kaldun A, Jiang Y, Senftleben A, Kurka M, Moshammer R, Ullrich J, Pfeifer T. Enhancing temporal resolution in pump-probe experiments with noisy pulses. EPJ WEB OF CONFERENCES 2013. [DOI: 10.1051/epjconf/20134102001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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35
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Camus N, Fischer B, Kremer M, Sharma V, Rudenko A, Bergues B, Kübel M, Johnson NG, Kling MF, Pfeifer T, Ullrich J, Moshammer R. Attosecond correlated dynamics of two electrons passing through a transition state. PHYSICAL REVIEW LETTERS 2012; 108:073003. [PMID: 22401200 DOI: 10.1103/physrevlett.108.073003] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Indexed: 05/31/2023]
Abstract
The strong-field induced decay of a doubly excited, transient Coulomb complex Ar**→Ar(2+)+2e(-) is explored by tracing correlated two-electron emission in nonsequential double ionization of Ar as a function of the carrier-envelope phase. Using <6 fs pulses, electron emission is essentially confined to one optical cycle. Classical model calculations support that the intermediate Coulomb complex has lost memory of its formation dynamics and allows for a consistent, though model-dependent definition of "emission time," empowering us to trace transition-state two-electron decay dynamics with sub-fs resolution. We find a most likely emission time difference of ∼200±100 as.
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36
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Krishnan SR, Fechner L, Kremer M, Sharma V, Fischer B, Camus N, Jha J, Krishnamurthy M, Pfeifer T, Moshammer R, Ullrich J, Stienkemeier F, Mudrich M, Mikaberidze A, Saalmann U, Rost JM. Dopant-induced ignition of helium nanodroplets in intense few-cycle laser pulses. PHYSICAL REVIEW LETTERS 2011; 107:173402. [PMID: 22107516 DOI: 10.1103/physrevlett.107.173402] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Indexed: 05/31/2023]
Abstract
We demonstrate ultrafast resonant energy absorption of rare-gas doped He nanodroplets from intense few-cycle (~10 fs) laser pulses. We find that less than 10 dopant atoms "ignite" the droplet to generate a nonspherical electronic nanoplasma resulting ultimately in complete ionization and disintegration of all atoms, although the pristine He droplet is transparent for the laser intensities applied. Our calculations at those intensities reveal that the minimal pulse length required for ignition is about 9 fs.
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37
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Kremer M, Hofrichter C, Fischer B, Sharma V, Camus N, Pfeifer T, Moshammer R, Ullrich J. Minimizing dispersive distortions in carrier-envelope phase sweeping with glass wedges. OPTICS LETTERS 2011; 36:1455-1457. [PMID: 21499388 DOI: 10.1364/ol.36.001455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A systematic experimental study is performed to examine the f-2f technique for sweeping the carrier-envelope phase (CEP) of few-cycle laser pulses by changing the amount of positive dispersion in the extracavity beam path. Slightly changing the dispersion not only changes the CEP but affects the entire spectral-phase function. As a result, large discrepancies are found between the true CEP as independently measured with a stereo-above-threshold-ionization spectrometer and the CEP detected by an f-2f interferometer when sweeping the phase with glass wedges. A new CEP-stabilization scheme is proposed and experimentally shown to significantly improve the performance of CEP sweeping.
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38
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Bosbach C, Pfeifer T, Depiereux F. Neue Konzepte für ein faserbasiertes Messsystem zur absoluten Abstandsmessung (New Concepts for a Fiber Based System for Absolute Distance Measurements). ACTA ACUST UNITED AC 2009. [DOI: 10.1524/teme.70.2.85.20103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
Der Einsatz und die Nutzung von miniaturisierten Bauteilen oder Produkten ist seit Jahren etabliert, sei es in der Telekommunikation oder Automobilbranche. Jedoch ist die Frage nach geeigneten Produktionsverfahren und -mitteln immer aktuell und ist in vielen Fällen noch nicht ausreichend gelöst bzw. es stehen noch Lösungen aus. Gerade Bereiche der Prozesskontrolle bzw. -regelung mittels Messtechnik bergen Entwicklungspotentiale. Der vorliegende Artikel zeigt die Entwicklung eines faserbasierten Abstandsmesssystems und dessen Einsatzmöglichkeiten.
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Walter D, Pfeifer T, Winterfeldt C, Kemmer R, Spitzenpfeil R, Gerber G, Spielmann C. Adaptive spatial control of fiber modes and their excitation for high-harmonic generation. OPTICS EXPRESS 2006; 14:3433-3442. [PMID: 19516488 DOI: 10.1364/oe.14.003433] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We present the control of high-harmonic generation (HHG) in hollow fibers using adaptive pulse shaping techniques. The shaping capabilities of our spatial light modulator (SLM) are demonstrated by the excitation of specific fiber modes inside a hollow fiber with a helium-neon laser. Afterwards spatially shaped ultrashort pulses are used to generate phase-matched high-harmonic radiation in a fiber. We show that by controlling the mode structure, we can manipulate the spatial and spectral properties of the generated harmonics.
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40
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Pfeifer T, Ammermann A, Leber M, Effert R. Ophthalmologische Beschwerdesymptomatik bei Glioblastoma multiforme. Klin Monbl Augenheilkd 2005. [DOI: 10.1055/s-2005-922129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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41
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Brixner T, Krampert G, Pfeifer T, Selle R, Gerber G, Wollenhaupt M, Graefe O, Horn C, Liese D, Baumert T. Quantum control by ultrafast polarization shaping. PHYSICAL REVIEW LETTERS 2004; 92:208301. [PMID: 15169385 DOI: 10.1103/physrevlett.92.208301] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2004] [Indexed: 05/24/2023]
Abstract
We demonstrate that the use of time-dependent light polarization opens a new level of control over quantum systems. With potassium dimer molecules from a supersonic molecular beam, we show that a polarization-shaped laser pulse increases the ionization yield beyond that obtained with an optimally shaped linearly polarized laser pulse. This is due to the different multiphoton ionization pathways in K2 involving dipole transitions which favor different polarization directions of the exciting laser field. This experiment is a qualitative extension of quantum control mechanisms which opens up new directions giving access to the three-dimensional temporal response of molecular systems.
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42
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Krohne I, Pfeifer T, Zacher M, Depiereux F, Stepp H. New concept for the development of a confocal endomicroscope. BIOMED ENG-BIOMED TE 2003; 47 Suppl 1 Pt 1:206-8. [PMID: 12451818 DOI: 10.1515/bmte.2002.47.s1a.206] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
It is one of modern medicine's top priorities to reduce the stress for the patient during diagnosis and therapy by designing minimally invasive applications of medical techniques. Microsystems technology has always held the key to minimally invasive solutions in surgery and micro-endoscopy. The new measuring system KOMED is currently developed for the application of in-vivo cellular microscopy. This approach is based on the concept of a miniaturised fibre-optical confocal microscope. The application range of this microsensor system includes the minimally invasive optical biopsy for purposes such as the early detection of tumour cells. In this paper the concept of the KOMED system is described, as well as technical challenges to be solved in the project.
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43
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Krohne I, Pfeifer T, Meier R, Stepp H, Zimmermann N, Warnck S, Krampitz O, Höper R, Ehrhardt A, Irion KM, Menschig A, Rupp T. ENTWICKLUNG EINES KONFOKALEN MIKROENDOSKOPS - KOMED. BIOMED ENG-BIOMED TE 2003. [DOI: 10.1515/bmte.2003.48.s1.560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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44
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Pfeifer T, Klaus U, Hoffmann R, Spiteller M. Characterisation of humic substances using atmospheric pressure chemical ionisation and electrospray ionisation mass spectrometry combined with size-exclusion chromatography. J Chromatogr A 2001; 926:151-9. [PMID: 11554407 DOI: 10.1016/s0021-9673(01)00805-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Humic substances were analysed by atmospheric pressure chemical ionisation (APCI) and electrospray ionisation (ESI) mass spectrometry in positive and negative modes. Using APCI the average m/z range of humic substances was reduced 5-fold compared to ESI. High-resolution time-of-flight mass spectrometry revealed the formation of multiply charged molecules in the ESI mode. Moreover, it was possible to obtain daughter ion mass spectra of humic substances by nanospray tandem mass spectrometry. The size-exclusion chromatography elution profile of humic substances was highly influenced by the pH of the analyte solution. By contrast, the pH had no significant influence on the observed mass spectra of humic substances.
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45
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Lüttge U, Pfeifer T, Fischer-Schliebs E, Ratajczak R. The role of vacuolar malate-transport capacity in crassulacean acid metabolism and nitrate nutrition. Higher malate-transport capacity in ice plant after crassulacean acid metabolism-induction and in tobacco under nitrate nutrition. PLANT PHYSIOLOGY 2000; 124:1335-48. [PMID: 11080309 PMCID: PMC59231 DOI: 10.1104/pp.124.3.1335] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2000] [Accepted: 07/14/2000] [Indexed: 05/23/2023]
Abstract
Anion uptake by isolated tonoplast vesicles was recorded indirectly via increased H(+)-transport by H(+)-pumping of the V-ATPase due to dissipation of the electrical component of the electrochemical proton gradient, Deltamu(H+), across the membrane. ATP hydrolysis by the V-ATPase was measured simultaneously after the Palmgren test. Normalizing for ATP-hydrolysis and effects of chloride, which was added to the assays as a stimulating effector of the V-ATPase, a parameter, J(mal)(rel), of apparent ATP-dependent malate-stimulated H(+)-transport was worked out as an indirect measure of malate transport capacity. This allowed comparison of various species and physiological conditions. J(mal)(rel) was high in the obligate crassulacean acid metabolism (CAM) species Kalanchoë daigremontiana Hamet et Perrier, it increased substantially after CAM induction in ice plant (Mesembryanthemum crystallinum), and it was positively correlated with NO(3)(-) nutrition in tobacco (Nicotiana tabacum). For tobacco this was confirmed by measurements of malate transport energized via the V-PPase. In ice plant a new polypeptide of 32-kD apparent molecular mass appeared, and a 33-kD polypeptide showed higher levels after CAM induction under conditions of higher J(mal)(rel). It is concluded that tonoplast malate transport capacity plays an important role in physiological regulation in CAM and NO(3)(-) nutrition and that a putative malate transporter must be within the 32- to 33-kD polypeptide fraction of tonoplast proteins.
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46
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Pfeifer T, Drewello M, Schierhorn A. Using a matrix-assisted laser desorption/ionization time-of-flight mass spectrometer for combined in-source decay/post-source decay experiments. JOURNAL OF MASS SPECTROMETRY : JMS 1999; 34:644-650. [PMID: 10394629 DOI: 10.1002/(sici)1096-9888(199906)34:6<644::aid-jms816>3.0.co;2-h] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Mass spectrometric experiments with fragment ions have not yet been possible with a matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometer because intense signals of fragment ions were rarely observed during continuous extraction and the mass resolution of in-source formed fragment ions has been low. This paper describes a combination of MALDI in-source decay and post-source decay experiments on a MALDI-TOF mass spectrometer equipped with delayed extraction. Fragment ions initially formed in the ion source were selected by the precursor ion gate and investigated by post-source decay. The in-source formed fragment ions were sufficiently excited to undergo further metastable decay. The new method was applied to linear peptides, the cyclic peptide gramicidin S and a pentasaccharide, leading to unambiguous structural information.
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47
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Pfeifer T, Rücknagel P, Kuellertz G, Schierhorn A. A strategy for rapid and efficient sequencing of Lys-C peptides by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry post-source decay. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 1999; 13:362-369. [PMID: 10209874 DOI: 10.1002/(sici)1097-0231(19990315)13:5<362::aid-rcm492>3.0.co;2-i] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A modification procedure for Lys-C peptides is described which simplifies the correct assignment of the amino acid sequence. Release of the C-terminal lysine from Lys-C peptides by carboxypeptidase B and subsequent N-terminal acetylation of the resulting peptides leads to predictable shifts of the C- and N-terminal fragment ions in Matrix-assisted laser desorption/ionisation time-of-flight post-source decay mass spectra and facilitates the correct assignment of mostly complete amino acid sequences for oligopeptides. The derived sequences of peptides from unknown proteins were used to search in databases for homologous protein sequences. Our method was applied to an unknown protein isolated from eggs of Drosophila melanogaster, resulting in the identification of a peptidyl prolyl cis-trans-isomerase.
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48
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Pfeifer T, Siegler S, Varnhagen V. Business excellence through a robust development process for innovative products. ACTA ACUST UNITED AC 1998. [DOI: 10.1080/0954412988875] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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49
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50
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Fehlow P, Walther F, Pfeifer T, Schuchard UM. [Robin-Silverman-Smith (fetal face) syndrome]. KLINISCHE PADIATRIE 1995; 207:354-5. [PMID: 8569140 DOI: 10.1055/s-2008-1046568] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Report of a case of the fetal face syndrome associated with severe oligophrenia and septum pellucidum cyste in a male patient aged 30 years. The case demonstrates the good prognosis of the hypogenitalism resp. small genitalia; the correct diagnosis in this syndrome can the patients save a plastic of the penis.
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