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11.
We have used a variety of microscopic techniques to reveal the structure and motion of flux line arrangements, when the flux
lines in low T
c type II superconductors are caused to move by a transport current. Using small-angle neutron scattering by the flux line
lattice (FLL), we are able to demonstrate directly the alignment by motion of the nearest-neighbor FLL direction. This tends
to be parallel to the direction of flux line motion, as had been suspected from two-dimensional simulations. We also see the
destruction of the ordered FLL by plastic flow and the bending of flux lines. Another technique that our collaboration has
employed is the direct measurement of flux line motion, using the ultra-high-resolution spectroscopy of the neutron spin-echo
technique to observe the energy change of neutrons diffracted by moving flux lines. The muon spin rotation (μSR) technique gives the distribution of values of magnetic field within the FLL. We have recently succeeded in performing
μSR measurements while the FLL is moving. Such measurements give complementary information about the local speed and orientation
of the FLL motion. We conclude by discussing the possible application of this technique to thin film superconductors. 相似文献
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Dr. Jianing Xie Dr. Axel Pahl Dr. Adrian Krzyzanowski Anna Krupp Dr. Jie Liu Sandra Koska Beate Schölermann Dr. Ruirui Zhang Jana Bonowski Dr. Sonja Sievers Prof. Dr. Carsten Strohmann Dr. Slava Ziegler Dr. Michael Grigalunas Prof. Dr. Herbert Waldmann 《Angewandte Chemie (International ed. in English)》2023,62(48):e202310222
Monoterpene indole alkaloids (MIAs) are endowed with high structural and spatial complexity and characterized by diverse biological activities. Given this complexity-activity combination in MIAs, rapid and efficient access to chemical matter related to and with complexity similar to these alkaloids would be highly desirable, since such compound classes might display novel bioactivity. We describe the design and synthesis of a pseudo-natural product (pseudo-NP) collection obtained by the unprecedented combination of MIA fragments through complexity-generating transformations, resulting in arrangements not currently accessible by biosynthetic pathways. Cheminformatic analyses revealed that both the pseudo-NPs and the MIAs reside in a unique and common area of chemical space with high spatial complexity-density that is only sparsely populated by other natural products and drugs. Investigation of bioactivity guided by morphological profiling identified pseudo-NPs that inhibit DNA synthesis and modulate tubulin. These results demonstrate that the pseudo-NP collection occupies similar biologically relevant chemical space that Nature has endowed MIAs with. 相似文献
14.
Davis WC Christopher SJ Pugh RS Donard OF Krupp EA Point D Horvat M Gibicar D Kljakovic-Gaspic Z Porter BJ Schantz MM 《Analytical and bioanalytical chemistry》2007,387(7):2335-2341
This paper describes the development of two independent analytical methods for the extraction and quantification of methylmercury
from marine biota. The procedures involve microwave extraction, followed by derivatization and either headspace solid-phase
microextraction (SPME) with a polydimethylsiloxane (PDMS)-coated silica fiber or back-extraction into iso-octane. The identification
and quantification of the extracted compounds is carried out by capillary gas chromatography/mass spectrometric (GC/MS) and
inductively coupled plasma mass spectrometric (GC/ICP-MS) detection. Both methods were validated for the determination of
methylmercury (MeHg) concentrations in a variety of biological standard reference materials (SRMs) including fresh-frozen
tissue homogenates of SRM 1946 Lake Superior fish tissue and SRM 1974a organics in mussel tissue (Mytilus edulis) and then applied to the certification effort of SRM 1947 Lake Michigan fish tissue and SRM 1974b organics in mussel tissue
(Mytilus edulis). While past certifications of methylmercury in tissue SRMs have been based on two independent methods from the National
Institute of Standards and Technology (NIST) and participating laboratories, the methods described within provide improved
protocols and will allow future certification efforts to be based on at least two independent analytical methods within NIST. 相似文献
15.
Krupp EM Grümping R Furchtbar UR Hirner AV 《Analytical and bioanalytical chemistry》1996,354(5-6):546-549
Low temperature GC on-line coupled with an ICP/MS has been used as analytical device to detect organometallic and -metalloid compounds from various sediments of rivers and harbours in West Germany. The different species have been volatilized by derivatization with NaBH(4) and cryofocussed in a trap. Different alkylated species of As, Sn and Sb have been identified, while only methylated compounds of the elements Ge, Se, Te, Hg and Bi could be detected. 相似文献
16.
R. C. Rodríguez Martín‐Doimeadios T. Stoichev E. Krupp D. Amouroux M. Holeman O. F. X. Donard 《应用有机金属化学》2002,16(10):610-615
A synthesis method for the micro‐scale laboratory preparation of isotopically enriched monomethylmercury (MMHg) has been successfully established. This compound is an important standard for species‐specific isotope dilution analysis. The isotopically enriched MMHg has been synthesized from commercially available mercury oxide (201HgO) using methylcobalamin co‐enzyme as methylating agent. The time required is less than 2 h and the final yield is about 90%. The proposed method is faster than those previously reported in the literature. It allows work on a micro scale to control the use of expensive enriched isotope standard. It also allows control of unintentional formation of dimethylmercury. The enriched mercury‐containing reaction products were analyzed by capillary gas chromatography coupled to an inductively coupled plasma mass spectrometer after derivatization with sodium tetraethylborate. The isotopic composition, concentration, purity and stability of the synthesized, enriched MMHg have been investigated in order to establish standard protocols for MMHg isotope dilution analysis or isotope labeling incubation experiments. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
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KM Clauwaert Van Bocxlaer JF HJ Major JA Claereboudt WE Lambert Van den Eeckhout EM Van Peteghem CH De Leenheer AP 《Rapid communications in mass spectrometry : RCM》1999,13(14):1540-1545
This paper describes the investigation of the potential of a quadrupole orthogonal acceleration time-of-flight mass spectrometer (Q-TOF) equipped with an atmospheric pressure ionisation interface for quantitative measurements of small molecules separated by reversed phase liquid chromatography. To this end, the detection limits and linear dynamic range in particular were studied in an LC/MS/MS experiment using 3,4-methylenedioxymethamphetamine standards and 3,4-methylenedioxyethylamphetamine for internal standardisation. In a second phase, the experiment was repeated with real biological extracts (whole blood, serum, and vitreous humour). A calibration for 3,4-methylenedioxymethamphetamine and its metabolite 3,4-methylenedioxyamphetamine was prepared in each of these matrices again using 3,4-methylenedioxyethylamphetamine as internal standard. The resulting quantitative data were compared with those obtained by liquid chromatography with fluorescence detection for the same extracts. The Q-TOF results revealed excellent sensitivity and a linear dynamic range of nearly four decades (2-10 000 pg on-column, r(2) = 0.9998, 1/x weighting). Furthermore, all the calibration curves prepared in biological material were superimposable, LC/MS/MS and LC-fluorescence, and the quantitative results for actual samples compared very favourably. It was concluded that the Q-TOF achieves a linear dynamic range for quantitative LC/MS/MS work exceeding that of fluorescence detection and at much better absolute sensitivity. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
19.
Reinhard Niessner Wilfried Robers Andreas Krupp 《Fresenius' Journal of Analytical Chemistry》1991,341(3-4):207-213
Summary Laser-induced fluorescence is introduced as an analytical technique for the detection of particle-bound PAHs, which can be found as a result of most combustion processes. A quartz fiber is used to couple the light of a frequency-doubled excimer-pumped dye laser into the sensor head. The fluorescence light is detected using collecting optics, a set of interference filters and a photomultiplier. PAHs in different forms (crystalline, as homogeneous particles and coated on NaCl particles) were investigated. Fluorescence spectra and time-resolved signals, which exhibit characteristic decay times, are presented. 相似文献
20.
D. Krupp 《辐射效应与固体损伤》2019,174(11-12):1047-1052
ABSTRACTIn a novel approach using blended learning techniques members of the CHERNE network have organized novel courses. This report covers a course in Radiochemistry and Medical Dosimetry. Homework assignments on the global sustainability tools laid the foundation of simulation work on cyclotron targetry and radiochemical laboratory courses. A role play game on Medical Dosimetry concluded the one week of instructions. For the next course, the first year students prepare an instruction scheme for another batch of students and will give that instruction themselves. 相似文献