A5023595611- Rare-earth and actinide compounds
- Magnetic Properties of Alloys
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Electron Spin Resonance Studies
- Magnetism in coordination complexes
- Magnetic properties of thin films
- Lanthanide and Transition Metal Complexes
- Iron-based superconductors research
- DNA and Nucleic Acid Chemistry
- Crystallography and molecular interactions
- Advanced biosensing and bioanalysis techniques
- Advanced Condensed Matter Physics
- Metal complexes synthesis and properties
- Physics of Superconductivity and Magnetism
- Magnetic Properties and Applications
- Magnetic and transport properties of perovskites and related materials
- Intermetallics and Advanced Alloy Properties
- Advanced Fluorescence Microscopy Techniques
- Metallurgical and Alloy Processes
- Click Chemistry and Applications
- Porphyrin and Phthalocyanine Chemistry
- RNA Interference and Gene Delivery
- Ferrocene Chemistry and Applications
- Magnetic Properties and Synthesis of Ferrites
University of Bonn
1933-2024
Leibniz Institute for Applied Geophysics
2024
Max Planck Institute for Multidisciplinary Sciences
2022-2024
University of Göttingen
2023-2024
Augusta University
2023
Max Planck Institute for Biophysical Chemistry
2018-2021
Biogen (Switzerland)
2021
ETH Zurich
2016-2021
Friedrich-Alexander-Universität Erlangen-Nürnberg
2014-2016
Bielefeld University
2016
Numerous measurements of saturation magnetization Fe and Ni are reported. Saturation is determined by consideration all contributions in the change high magnetic fields, i.e., internal demagnetizing homogeneous rotations, paramagnetic terms. The value found for absolute iron σ0,∞ = 221.71±0.08 emu/g, corresponding to M 2.216 μB, good agreement with previously accepted values. For Ni, obtained 58.57±0.03 0.616 other previous data but 1.6% larger than Weiss Forrer's 0.606 μB.
Distance distribution information obtained by pulsed dipolar EPR spectroscopy provides an important contribution to many studies in structural biology. Increasingly, such is used integrative modeling, where it delivers unique restraints on the width of conformational ensembles. In order ensure reliability models and biological conclusions, we herein define quality standards for sample preparation characterization, measurements distributed dipole-dipole couplings between paramagnetic labels,...
Golden times for metal-based drugs? Alkynyl triphenylphosphine gold(I) complexes display interesting biological properties and show high potential future drug development. They are strong inhibitors of the enzyme thioredoxin reductase, trigger antiproliferative effects in tumor cells, influence cell metabolism, mitochondrial respiration, angiogenesis zebrafish embryos. Detailed facts importance to specialist readers published as "Supporting Information". Such documents peer-reviewed, but not...
The magnetomechanical ratio g′ and the spectroscopic factor g were measured on same samples of iron nickel. factors also for some Fe-Ni, Fe-Co, Co-Ni, alloys. experimental values are used to check Kittel-Van Vleck relations, whose exact form 1/g+1/g′ = 1 appears well satisfied. It is shown that effective geff′ an alloy, which given by quotient total magnetic moment angular momentum system, converts itself means relation 1/g+l/g′ formula Tsuya Wangsness, gives splitting geff a two-sublattice...
The magnetization and high-field susceptibility of disordered cold-worked Fe1-cAlc alloys with 0<c<or=0.51 have been determined at 4K in fields up to 150 kOe. well known initial magnetic behaviour is found extend about c approximately=0.25. At higher values the mean atomic moment decreases faster than a dilution but still has not vanished c=0.51, while an increasingly strong paramagnetic term simultaneously appears. experimental results, moments susceptibilities, are satisfactorily described...
In search of a reliable drying method, which might be used even under field conditions, microwave was compared to freeze-drying plant material. Leaves Ananas comosus and Avicennia germinans as well buds phloem Acer pseudoplatanus were checked for one or more the following substances: sugars, sugar alcohols, organic amino acids, total nitrogen, glycinebetaine. With most samples good agreement achieved between two methods. Only in case leaves, exhibited low pH high water content, did...
The authors present the results of XPS (X-ray photoemission spectroscopy) and XRA absorption) studies performed on several intermetallic cerium compounds (CeRh3, CeCo5, CeNi5, CeNi2, CeRu4B4, CePd3 CeBe13). In CeBe13, is known to be in so-called intermediate valence state; CeRh3 thought tetravalent state: Ce4+ (4f05d2). Finally for CeNi2 CeRu4B4 situation unclear. main purpose this paper show that these cannot deduced from measurements same way as it other rare-earth (Tm or Sm instance)....
Gold compounds with N-heterocyclic carbene (NHC) ligands have been widely described as potent thioredoxin reductase (TrxR) inhibitors and effective anticancer agents. However, despite these promising aspects structure–activity-relationship (SAR) studies still remain limited. In this study a structurally diverse library of gold(I) gold(III) NHC complexes was investigated for inhibitory capacity against TrxR antiproliferative activity in HT-29 human colon adenocarcinoma cells the aim...
Green fluorescent proteins (GFPs) are invaluable tools for modern cell biology. Even though many properties of GFP have been successfully engineered, a retaining brightness at low pH has not emerged. This limits the use in quantitative studies performed fluctuating or acidic conditions. We report engineering and characterisation tandem dimer (pH-tdGFP), bright stable that can be efficiently excited maintains its fluorescence Therefore, pH-tdGFP could act as marker cellular processes occur...
Abstract A catalytic system for titanocene‐catalyzed epoxide hydrosilylation is described. It features a straightforward preparation of titanocene hydrides that leads to reaction with low catalyst loading, high yields, and selectivity radical reduction. The mechanism was studied by suite methods, including kinetic studies, EPR spectroscopy, computational methods. An unusual resting state the observation an inverse rate order respect epoxide.
EPR-based nanometre distance measurements are becoming ever more important in structural biology. Usually the constraints measured between two nitroxide spin labels. Yet, a metal center and labels enable, e.g., localization of ions within tertiary fold biomolecules. Therefore, it is to find methods that provide such information quickly, with high precision reliability. In present study, methods, pulsed electron–electron double resonance (PELDOR) relaxation-induced dipolar modulation...
Low-temperature heat capacity data are presented for a series of AuCu3 type MPd3 compounds (M=Ce, La, Lu, Y and Sc). The coefficient gamma the linear term electronic specific non-magnetic ranges from 0.28 LaPd3 to 8.2 mJ mol-1 K-2 ScPd3 reflects lower density states at Fermi surface than that M or Pd. high value intermediate valence CePd3 is confirmed shown vary with Ce content near stoichiometry: maximum 38.6 obtained while contribution T3 found be very small. electrical resistivity CePd3+x...
Abstract Organometallic conjugates consisting of a gold(I) N ‐heterocyclic carbene (NHC) moiety and naphthalimide were prepared investigated as cytotoxic agents that interact with both DNA the disulfide reductase enzyme thioredoxin (TrxR). The complexes potent intercalators related to their partial structure, inhibited TrxR consequence incorporation moiety, triggered efficient effects in MCF‐7 breast HT‐29 colon adenocarcinoma cells. Strong on tumor cell metabolism noted for most complex,...
Electron paramagnetic resonance (EPR) based distance measurements in combination with site directed spin labeling is an important method for determining biomolecular structures and their conformational changes. Commonly used labels are nitroxides but trityl radicals emerging as a new type of specifically measurements. Here, systematic evaluation presented the performance different EPR pulse sequences measuring inter-spin distances using labels. The model systems two bistrityl one tristrityl...
Spectroscopic and biophysical methods for structural determination at atomic resolution are fundamental in studies of biological function. Here we introduce an approach to measure molecular distances bio-macromolecules using 19 F nuclear spins nitroxide radicals combination with high-frequency (94 GHz/3.4 T) electron-nuclear double resonance (ENDOR). The small size large gyromagnetic ratio the label enables access up about 1.5 nm accuracy 0.1-1 Å. experiment is not limited by...
Abstract Known molecular, “caged” siRNAs are activated by UV light. Since the light of this type is toxic to cells, uncaging can cause undesired side effects. A modular, molecular system for designing reported, which be non‐toxic in live cells. For example, responsive green and red described. The mediated 1 O 2 photogenerated on a photosensitizer, attached 3′‐terminus lagging strand. 5′‐terminus guide strand alkylated (“caged”) with 9‐anthracenyl residue. latter fragment reacts formation...
The structure of Jahn–Teller distorted copper–nitroxide complexes in neutral and acidic solutions is investigated using EPR distance measurements taking into account the influence orientation selectivity multispin effects.
A homoleptic bisnitroxide complex of manganese(II) was synthesized as a model system for EPR spectroscopic distance determinations involving high-spin metal ions and more than one distance. The performance the RIDME experiment is compared with that frequently used PELDOR experiment. It shown yields both distances, Mn(II)–nitroxide nitroxide–nitroxide, they can be separated to certain extent, whereas only Both pulse sequences yield artifacts, either due multispin effects or higher...
Ribonucleotide reductases (RNRs) catalyze the reduction of ribonucleotides to deoxyribonucleotides, thereby playing a key role in DNA replication and repair. Escherichia coli class Ia RNR is an α2β2 enzyme complex that uses reversible multistep radical transfer (RT) over 32 Å across its two subunits, α β, initiate, using metallo-cofactor β2, nucleotide α2. Each step proposed involve distinct proton-coupled electron-transfer (PCET) process. An unresolved RT involving Y356(β) Y731(α) α/β...
Abstract Riboswitches control gene regulation upon external stimuli such as environmental factors or ligand binding. The fluoride sensing riboswitch from Thermotoga petrophila is a complex regulatory RNA proposed to be involved in resistance F − cytotoxicity. details of structure and dynamics underpinning the mechanism are currently debated. Here we demonstrate that combination pulsed electron paramagnetic resonance (ESR/EPR) spectroscopies, detecting distances angstrom nanometre range, can...
Goldene Zeiten für Metallwirkstoffe? Alkinyl(triphenylphosphan)gold(I)-Komplexe zeigen interessante biologische Aktivität und haben ein vielversprechendes Potenzial die Wirkstoffentwicklung. Sie stellen starke Hemmstoffe des Enzyms Thioredoxin-Reduktase dar, lösen zellwachstumshemmende Effekte bei kultivierten Tumorzellen aus, beeinflussen den Tumorzellmetabolismus mitochondriale Atmung bewirken antiangiogene in Zebrafischembryos. Detailed facts of importance to specialist readers are...
Saturation magnetization measurements of Ni-Pd alloys show for a Pd concentration range c, 0–50 at. %, linear decrease the mean atomic moment according to M = MNi−0.11c, with MNi 0.616 μB. The extrapolated is 0.51 Ferromagnetic resonance at 35 GHz hyperbolic increase g factor addition. calculated spin moments vary linearly as Msp 0.56−0.17c, indicating 0.39 hole in 4d band Pd. would be 2.58, non-negligible orbital contribution.