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Combined Confocal Atomic Force Microscope Setup for Quantum Sensing Applications with Sub diffractional Spatial Resolution
Full text linkQuantum sensors find applications ranging from material science to biophysics. Nitrogen vacancy NV center in diamond has been successfully implemented for measuring various types of signals. Optical NV center readout, routinely used in confocal microscopes, allows achieving high spatial resolution down to the diffraction limit. This work describes in detail the combined confocal atomic force microscope confocal AFM , which takes advantage of sharp AFM cantilevers, and shows its possible applications for nanoscale resolution. It demonstrates the sub diffractional localization of NV centers with platinum coated cantilevers and the ability to separately address optically unresolved sensors using cantilevers with ferromagnetic coating. The presented setup exhibits a lateral resolution of 13 amp; 8201;nm, providing a tool for nanoscale quantum sensin
Synergistic effect of sidewall holes and encapsulated phosphorus to improve lithium storage in single walled carbon nanotubes
No full textThe paper presents experimental and theoretical evidence that filling holey single walled carbon nanotubes hSWCNTs with phosphorus creates an anode material with increased lithium storage capacity. Tuball SWCNTs were purified of the catalyst, opened at the ends, and treated with hot mineral acids, followed by annealing in argon to reduce the sizes of the bundle and create holes in the walls. According to transmission electron microscopy, Raman scattering and near edge X ray absorption fine structure NEXAFS spectroscopy studies, sidewall defects affect the phosphorus vapor condensation into short and disordered chains inside the nanotubes. The interaction of thermally evaporated lithium with empty and phosphorus filled SWCNTs was studied using model X ray photoelectron and NEXAFS spectroscopy experiments at a synchrotron radiation source. In the case of phosphorus filled holey SWCNTs P hSWCNTs , a high dispersion of lithium along the nanotube walls and the formation of lithium phosphide inside were detected. Density functional theory calculations showed that the presence of encapsulated phosphorus reduces the energy barrier for lithium to penetrate through the hole into the nanotube. Electrochemical testing confirmed the synergistic effect of sidewall holes and encapsulated fibrous phosphorus in improving charge storage capacity in the lithium ion battery. The P hSWCNTs electrode delivered 946 mA h g amp; 8722;1 at a current density of 0.1 A g amp; 8722;1, which is 2 times higher than that of the analogue with intact walls, and demonstrated stable operation at 2 A g amp; 8722;1 for 100 discharge charge cycles, achieving amp; 8764;100 Coulombic efficienc
Soft phonon and the central peak at the cubic to tetragonal phase transition in SrTiO3
Full text linkThe continuous displacive phase transition in SrTiO3 near amp; 119879; amp; 119888; amp; 8776;105 K features a central elastic peak in neutron scattering investigations at temperatures above amp; 119879; amp; 119888;, i.e., before the corresponding soft phonon mode is overdamped upon cooling. The origin of this central peak is still not understood. Here, we report an inelastic x ray scattering investigation of the cubic to tetragonal phase transition in SrTiO3. We compare quantitatively measurements of the soft phonon mode on two differently grown samples and discuss the findings regarding results from thermodynamic and transport probes such as specific heat and thermal conductivity. Furthermore, we use inelastic x ray scattering to perform elastic scans with both high momentum and milli electronvolt energy resolution and, thus, are able to separate elastic intensities of the central peak from low energy quasielastic phonon scattering. Our results indicate that the evolution of the soft mode is similar in both samples though the intensities of the central peak differ by a factor of four. Measurements revealing anisotropic correlation lengths on cooling towards amp; 119879; amp; 119888;, indicate that local properties of the crystals to which collective lattice excitations are insensitive are likely at the origin of the central elastic line in SrTiO
Photopolymerized gel polymer electrolytes with cyclic carbonate side chains for Li organic batteries at room temperature
Full text linkIn this study, we developed gel polymer electrolytes GPEs containing cyclic carbonate side chains produced via UV induced free radical polymerization, a fast cost efficient synthesis route, for Li organic batteries. Cyclic carbonate methacrylate CCMA was copolymerized with diethylene glycol methyl ether methacrylate DEGMEM for 1 h. Then the resultant polymer films were swelled in 1 M LiPF6 in EC DMC 50 50, v v with an electrolyte uptake of 500 . These novel GPEs an ionic conductivity of 1.1 mS cm 1 at 20 degrees C were electrochemically tested in Li PTMA cells in comparison with LP30. They were found to show maximum discharge capacities 62.6 vs. 63.9 mAh g 1, GPE vs. LP30 at 0.1 C in addition to better compatibility with Li anodes 25.7 vs. 40.2 mV overpotential in Li stripping plating tests and a comparable electrochemical stability window. The results confirm that these GPEs are promising candidates for Li organic batterie
Supramolecular Polymer Bottlebrushes In Situ Assessment of Noncovalent Assemblies in Human Serum by Analytical Ultracentrifugation
Full text linkFor nanomedical targeting and drug delivery purposes, the noncovalent assembly of polymer building blocks into defined nanostructures is an intense area of research. One of the key assets desirable to know for the potential nanocarrier is the stability under conditions close to those in application scenarios. Here, a series of polymer building blocks based on poly ethylene glycol PEG , which comprise a functional end group facilitating self assembly into supramolecular polymer bottlebrushes SPBs , is hydrodynamically studied. The building blocks, and consequently the assemblies, are labeled with a cyanine5 Cy5 dye enabling selective tracing of the materials in human serum HS in analytical ultracentrifugation AUC experiments. Our experiments reveal a long term stability of the noncovalent assemblies over one month of storage of the materials in HS at body temperature. At the same time, the interaction of some of the Cy5 moieties with the transport protein human serum albumin HSA is evidence
pi Lewis Base Activation of Carbonyls and Hexafluorobenzene
No full textWe report hitherto elusive side on amp; 951;2 bonded palladium 0 carbonyl anthraquinone, benzaldehyde and arene benzene, hexafluorobenzene palladium 0 complexes and present the catalytic hydrodefluorination of hexafluorobenzene by cyclohexene. The comparison with respective cyclohexene, pyridine and tetrahydrofuran complexes reveals that the experimental ligand binding strengths follow the order THF lt;C6H6 lt;C6F6 lt;cyclohexene lt;pyridine lt;benzaldehyde lt;anthraquinone. To understand this surprising order, the complexes electronic structures were elucidated by nuclear magnetic resonance NMR , single crystal X Ray diffraction sc XRD , ultraviolet visible UV Vis electronic absorption, infrared IR vibrational, Pd L3 edge X ray absorption XAS , and X ray photoelectron XP spectroscopic techniques, complemented by Density Functional Theory DFT calculations including energy decomposition EDA NOCV and effective oxidation state EOS analyses. For benzene, pyridine and cyclohexene, bonding follows the donor acceptor picture of the Dewar Chatt Duncanson model. In stark contrast, hexafluorobenzene, benzaldehyde and anthraquinone bind via essentially the amp; 960; channel only and thus as amp; 960; analogues of Z acceptor ligands. This contribution elucidates the control of functional group selectivity in palladium 0 catalysis and delineates a novel strategy to activate electron deficient amp; 960; system
Pr and Pfr structures of plant phytochrome A
Full text linkPhytochromes are biliprotein photoreceptors widespread amongst microorganisms and ubiquitous in plants where they control developmental processes as diverse as germination, stem elongation and floral induction through the photoconversion of inactive Pr to the Pfr signalling state. Here we report crystal structures of the chromophore binding module of soybean phytochrome A, including 2.2 amp; 8201; XFEL structures of Pr and Pfr at ambient temperature and high resolution cryogenic structures of Pr. In the Pfr structure, the chromophore is exposed to the medium, the D ring remaining amp; 945; facial following the likely clockwise photoflip. The chromophore shifts within its pocket, while its propionate side chains, their partners as well as three neighbouring tyrosines shift radically. Helices near the chromophore show substantial shifts that might represent components of the light signal. These changes reflect those in bacteriophytochromes despite their quite different signalling mechanisms, implying that fundamental aspects of phytochrome photoactivation have been repurposed for photoregulation in the eukaryotic plan
Conductivity hysteresis in MXene driven by structural dynamics of nanoconfined water
Full text linkWater under 2D confinement exhibits unique structural and dynamic behaviors distinct from bulk water, including phase transitions and altered hydrogen bonding networks, making it of great scientific interest. While confinement in 2D materials like graphene, mica, or hexagonal boron nitride has been reported, their lack of intrinsic hydrophilicity or metallic conductivity limits their suitability for probing the interplay between confined water and electronic transport. MXenes, a family of 2D transition metal carbides and nitrides, overcome these limitations by combining high metallic conductivity 104 amp; 8201;S amp; 8201;cm amp; 8722;1 with hydrophilicity, offering a unique platform to investigate confined water dynamics and their influence on electronic properties. Here, we show that temperature and confinement drive structural transitions of water within MXene interlayers, including the formation of localized ice clusters, amorphous ice, and dynamic hydrogen bonded networks. These transformations disrupt stacking order, inducing a reversible metal to semiconductor transition and conductivity hysteresis in MXene films. Upon heating to 340 amp; 8201;K, the dissociation of ice clusters restores interlayer spacing and metallic behavior. Our findings experimentally establish MXenes as an exceptional platform for studying the phase change of confined water, offering new insights into how nanoscale water dynamics modulate electronic properties and enabling the design of advanced devices with tunable interlayer interaction
Improving the Identification of Layers in 3D Images of Ancient Papyrus using Artificial Neural Networks
No full textThe non invasive digital unfolding of ancient documents, such as folded papyrus packages, from 3D image data aims to reveal previously hidden writing without risking to damage the precious documents. One of the main tasks in this process is the geometric reconstruction of the writing sub strate, which is a prerequisite for its subsequent unfolding. All current reconstruction methods require the existence of an interspace between different layers of the document to ensure a correct topology. Layers that appear merged to gether in the 3D image often result in wrong connections between layers and thus also in a wrong topology of the reconstructed geometry, which hinders the successful unfolding. Here, we propose to use a neural network to facilitate the discrimination of the layers. Using papyrus documents as an example of a particularly difficult writing material, we show that our approach significantly reduces the number of wrong connections and improves the overall identification of the layers. This in turn enables fully automatic digital unfolding of large areas of highly complex papyrus packages. Utilizing explainable AI XAI further allows us to explore the results of the applied neural networ
A Framework for the AI based Visualization and Analysis of Massive Amounts of 4D Tomography Data for End Users of Beamlines
Full text linkThe size of 4D tomography datasets acquired at synchrotron or neutron imaging facilities can reach several terabytes, which presents a significant challenge for their evaluation. This paper presents a framework that allows a compressed dataset to be kept in memory and makes it possible to evaluate and manipulate the dataset without requiring enough memory to decompress the entire dataset. The framework enables the compensation of imaging artifacts, including the compression artifacts of the 4D dataset, through the integration of neural networks. The reduction of imaging artifacts can be performed at the imaging facility or at the user s home institution. This framework reduces the computational burden on the computing infrastructure of large synchrotron and neutron facilities by allowing end users to process datasets on their institution s computers. This is made possible by compressing TBs of data to less than 128 GB, allowing powerful PCs to process TBs of 4D tomography dat