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Excitation and detection of coherent nanoscale spin waves via extreme ultraviolet transient gratings
Get PDFThe advent of free electron lasers has opened the opportunity to explore interactions between extreme ultraviolet EUV photons and collective excitations in solids. While EUV transient grating spectroscopy, a noncollinear four wave mixing technique, has already been applied to probe coherent phonons, the potential of EUV radiation for studying nanoscale spin waves has not been harnessed. Here we report EUV transient grating experiments with coherent magnons in Fe Gd ferrimagnetic multilayers. Magnons with tens of nanometers wavelengths are excited by a pair of femtosecond EUV pulses and detected via diffraction of a probe pulse tuned to an absorption edge of Gd. The results unlock the potential of nonlinear EUV spectroscopy for studying magnons and provide a tool for exploring spin waves in a wave vector range not accessible by established inelastic scattering technique
Anwendung und Erweiterung der Amber Stop Codon Technologie mit Potential zur Generierung biomedizinischer Therapeutika
No full textComputational Investigation of the Structure and Reactivity of Metal Nitrogen Carbons for Electrocatalysis
No full textComparison of Bayesian optimization and the reduction of resonance driving terms in the optimization of the dynamic aperture of the BESSY III MBA lattice
Get PDFHZB is currently designing the lattice for BESSY III, the successor of the 1.7 GeV electron storage ring running in Berlin since 1998. HZB follows a deterministic lattice design strategy, where the natural substructures of a non hybrid MBA lattice are optimized separately. The substructures consist of only a few parameters, that can be derived from the strategic goals of the project. In the next step, the focusing and de focusing sextupole families are split up, to optimize the longitudinal and the transverse apertures. The paper compares two approaches to select the optimal sextupole strengths. The first one is multi objective Bayesian optimization, where the dynamic aperture volume from tracking simulations is used as an objective to be maximized. The second approach does not involve tracking and minimizes the geometric and chromatic resonance driving terms. The comparison of the two results includes their quality in terms of the size of the achievable 3D dynamic aperture and the computational effort involve
Variability aware modeling of electrochemical metallization memory cells
Get PDFResistively switching electrochemical metallization memory cells are gaining huge interest since they are seen as promising candidates and basic building blocks for future computation in memory applications. However, especially filamentary based memristive devices suffer from inherent variability, originating from their stochastic switching behavior. A variability aware compact model of electrochemical metallization memory cells is presented in this study and verified by showing a fit to experimental data. It is an extension of the deterministic model. Since this extension consists of several different features allowing for a realistic variability aware fit, it depicts a unique model comprising physics based, stochastically and experimentally originating variabilities and reproduces them well. In addition, a physics based model parameter study is executed, which enables a comprehensive view into the device physics and presents guidelines for the compact model fitting procedur
A soft molecular single source precursor approach to synthesize a nanostructured Co9S8 pre catalyst for efficient water oxidation and biomass valorization
Get PDFThe molecular single source precursor SSP route has emerged as a promising avenue for synthesizing highly efficient electro pre catalysts tailored for both oxygen evolution OER and organic electrooxidation reactions. This study introduces a novel [CoII PyHS 4 OTf 2] molecular complex, offering a facile route to access the nanocrystalline Co9S8 phase. Upon application in alkaline OER, Co9S8 displayed remarkably high electrocatalytic activity across various metrics, including overpotentials, Tafel slopes, faradaic efficiency, charge transfer resistance, turnover frequency, electrochemical surface area, Co redox active sites, and long term stability at industrially relevant current densities for 80 h at 100 mA cm amp; 8722;2 outperforming its Co based counterparts under identical conditions. In depth analysis employing several ex situ techniques revealed the complete leaching of sulfur and irreversible reconstruction of Co9S8 into a cobalt oxyhydroxide active phase during the OER. Moreover, quasi in situ Raman spectroscopy provided insights into the presence of CoIVO2 active species under operational OER conditions, along with the formation of the Co superoxide intermediate. Beyond OER applications, the Co9S8 derived active phase demonstrated notable efficiency in catalyzing the selective oxidation of biomass derived glycerol and furan 2 carboxaldehyde to formate and furan 2 carboxylic acid, respectively, achieving yields exceeding 80 , with excellent reusability. A full hybrid water electrolysis cell has been developed, wherein biomass valorization with Co9S8, coupled with H2 production, resulted in a significant improvement in energy efficiency compared to conventional water splittin
Ergosterol promotes aggregation of natamycin in the yeast plasma membrane
No full textPolyene macrolides are antifungal substances, which interact with cells in a sterol dependent manner. While being widely used, their mode of action is poorly understood. Here, we employ ultraviolet sensitive UV microscopy to show that the antifungal polyene natamycin binds to the yeast plasma membrane PM and causes permeation of propidium iodide into cells. Right before membrane permeability became compromised, we observed clustering of natamycin in the PM that was independent of PM protein domains. Aggregation of natamycin was paralleled by cell deformation and membrane blebbing as revealed by soft X ray microscopy. Substituting ergosterol for cholesterol decreased natamycin binding and caused a reduced clustering of natamycin in the PM. Blocking of ergosterol synthesis necessitates sterol import via the ABC transporters Aus1 Pdr11 to ensure natamycin binding. Quantitative imaging of dehydroergosterol DHE and cholestatrienol CTL , two analogues of ergosterol and cholesterol, respectively, revealed a largely homogeneous lateral sterol distribution in the PM, ruling out that natamycin binds to pre assembled sterol domains. Depletion of sphingolipids using myriocin increased natamycin binding to yeast cells, likely by increasing the ergosterol fraction in the outer PM leaflet. Importantly, binding and membrane aggregation of natamycin was paralleled by a decrease of the dipole potential in the PM, and this effect was enhanced in the presence of myriocin. We conclude that ergosterol promotes binding and aggregation of natamycin in the yeast PM, which can be synergistically enhanced by inhibitors of sphingolipid synthesi
Measuring out quasi local integrals of motion from entanglement
Get PDFQuasi local integrals of motion are a key concept underpinning the modern understanding of many body localisation, a phenomenon in which interactions and disorder come together. Despite the existence of several numerical ways to compute them and in the light of the observation that much of the phenomenology of many properties can be derived from them it is not obvious how to directly measure aspects of them in real quantum simulations; in fact, hard experimental evidence is still missing. In this work, we propose a way to extract the real space properties of such quasi local integrals of motion based on a spatially resolved entanglement probe able to distinguish Anderson from many body localisation from non equilibrium dynamics. We complement these findings with a rigorous entanglement bound and compute the relevant quantities using tensor networks. We demonstrate that the entanglement gives rise to a well defined length scale that can be measured in experiment
Frustrated magnetism in octahedra based Ce6Ni6P17
No full textMagnetic frustration allows to access novel and intriguing properties of magnetic systems and has been explored mainly in planar triangular like arrays of magnetic ions. In this work, we describe the phosphide Ce6 amp; 8290;Ni6 amp; 8290;P17, where the Ce 3 ions accommodate in a body centered cubic lattice of Ce6 regular octahedra. From measurements of magnetization, specific heat, and resistivity, we determine a rich phase diagram as a function of temperature and magnetic field in which different magnetic phases are found. Besides clear evidence of magnetic frustration is obtained from entropy analysis. At zero field, a second order antiferromagnetic transition occurs at amp; 119879; amp; 119873;1 amp; 8776;1 K followed by a first order transition at amp; 119879; amp; 119873;2 amp; 8776;0.45 K. With magnetic field new magnetic phases appear, including a weakly first order transition which ends in a classical critical point and a third magnetic phase. We also study the exact solution of the spin 1 2 Heisenberg model in an octahedron which allows us a qualitative understanding of the phase diagram and compare with the experimental result
Macromolecular crystallography
No full textDespite recent advances in other structure determination methods, such as for instance cryo electron microscopy, macromolecular X ray crystallography is still by far the most popular experimental method for determining the three dimensional structure of biological macromolecules. More than 80 of all macromolecular structures determined to date, have been determined by crystallography. The physical principle behind X ray crystallography is the elastic scattering of electromagnetic waves by the crystalline sample. The resulting three dimensional diffraction pattern is recorded and analyzed. It contains the information on the spatial structure of the crystallized molecule, although the structure itself is not directly available from the diffraction pattern. The fact that only the amplitudes but not the phases of the X ray reflections can be measured is also known as the crystallographic phase problem, which has to be solved before the structure can be determine