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Efficient racemization of the pharmaceutical compound Levetiracetam using solvent free mechanochemistry
No full textWe present the racemization of an active pharmaceutical ingredient Levetiracetam using a novel approach. We demonstrate the design of a 100 solvent free process that proceeds by high energy milling inside a regular mixer mill. The kinetics of the racemization process is drastically improved compared to the solution based approach and illustrates the tremendous potential of mechanochemistry. In this study, we highlight the importance of mixing efficiency regarding data reproducibility, and we show, in particular, that water contamination has a negative impact on the reaction rate. Moreover, in situ X ray diffraction gives us first insights into the mechanisms involved in the solid state during the mechanochemical racemization proces
Enhancing the efficiency of a wavelength dispersive spectrometer based on a slitless design using a single bounce monocapillary
No full textThis paper introduces a novel slit less wavelength dispersive spectrometer design that incorporates a single bounce monocapillary with the goal of positioning the sample directly on the Rowland circle, thereby eliminating the need for a traditional entrance slit. This configuration enhances photon throughput while preserving energy resolution, demonstrated in comparative measurements on boron nitride and different lithium nickel manganese cobalt oxide cathodes. A common alternative to an entrance slit for limiting the source size on the Rowland circle is a customized design of the beamline involving a focusing optics unit consisting of two Kirkpatrick Baez mirrors close to the end station. The new slit less design does not rely on specialized beamlines and can be considered, thanks to the increased efficiency, for spectrometers using laboratory based sources equipped with equivalent optics. The comparative measurements found that the resolving power achieved was E amp; 916;E 1085 at 401.5 amp; 8197;eV incident energy, and the enhancement in detection efficiency was a factor of 3.7 due to more effective utilization of the X ray bea
Field induced spin liquid in the decorated square kagome antiferromagnet nabokoite KCu7TeO4 SO4 5Cl
Full text linkQuantum antiferromagnets based on the square kagome lattice are proving to be a fertile platform for realizing nontrivial phenomena in frustrated magnetism. Recently, several decorated square kagome compounds of the nabokoite family have been synthesized, allowing for experimental exploration of model Hamiltonians. Here, we carry out a theoretical analysis of KCu7TeO4 SO4 5Cl nabokoite using a Heisenberg Hamiltonian derived from density functional theory energy mapping. We employ classical Monte Carlo simulations to explain the two transitions experimentally observed in the low temperature magnetization curve. Interestingly, the intermediate field phase is also found in a purely two dimensional model and is described by a spin liquid featuring subextensive degeneracy with a ferrimagnetic component. We show that this phase can be approximated by a checkerboard lattice in a magnetic field. Finally, we assess the effects of quantum fluctuations in zero fields using the pseudo Majorana functional renormalization group metho
Substrate driven structural coherence in epitaxial hematite thin films for spintronics
No full textIn this work, we report the successful growth of high quality epitaxial hematite FeO thin films on three different substrates 0001 oriented sapphire, and 111 oriented perovskite structured SrTiO and LaAlO. Structural characterization confirms epitaxial growth with a 0001 out of plane orientation across all substrates. Synchrotron X ray diffraction reveals that the films are highly relaxed, exhibiting systematic in plane lattice variations driven by substrate induced strain. Notably, films grown on perovskite substrates display enhanced in plane crystal coherence compared to those on isostructural sapphire, indicating superior structural quality. These findings demonstrate the potential for seamless integration of hematite with perovskite oxides, enabling the development of high quality oxide heterostructures for spintronic application
Enhanced and Durable Light Driven Hydrogen Evolution by Cobalt Based Prussian Blue Analogs in Phospholipid Bilayers
Full text linkLight driven hydrogen H 2 evolution in water is performed using a series of cobalt based Prussian blue analogs M Co PBAs with M 3 II [Co III CN 6 ] 2 , M Co, Ni, Cu, Zn embedded in phospholipid bilayers with the amphiphilic ruthenium based photosensitizer RuC9. Hydrophobic surface functionalization of M Co PBA nanoparticles with oleylamine facilitates close proximity of the PBA to the photosensitizer within lipid bilayers of vesicles, enhancing photocatalytic performance. The type of metal and rigidity of the lipid environment significantly influences hydrogen evolution reaction efficiency, with the trend Ni gt; Co gt; Zn gt; Cu and DMPC gt; DOPC gt; DPPC. Among these, Ni Co PBA in DMPC 14 0 PEG2000 PE vesicles shows the highest efficiency, with a ninefold increase in H 2 production compared to the conventional aqueous system. This sustained activity is attributed to the efficient electron transfer and the scaffold s stability. This study provides valuable insights for the development of scalable and cost effective photocatalytic technologie
Effect of RNA on the supramolecular architecture of alpha synuclein fibrils
Full text linkStructural changes associated with protein aggregation are challenging to study, requiring the combination of experimental techniques providing insights at the molecular level across diverse scales, ranging from nanometers to microns. Understanding these changes is even more complex when aggregation occurs in the presence of molecular cofactors such as nucleic acids and when the resulting aggregates are highly polymorphic. Infrared IR spectroscopy is a powerful tool for studying protein aggregates since it combines the label free sensitivity to the cross amp; 946; architecture, an inherent feature of protein supra molecular aggregates, with the possibility to reach nanoscale sensitivity by leveraging atomic force microscopy AFM assisted detection. Here, we present a combined approach that detects IR spectral markers of aggregation using various IR spectroscopy techniques, covering micro to nanoscale ranges, to study the effect of RNA on the supramolecular architecture of alpha synuclein amyloid aggregates. We show a clear impact of RNA consistent with enhanced intermolecular forces, likely via a stronger hydrogen bonded network stabilizing the cross beta architecture. AFM assisted IR spectroscopy was crucial to assess that the more ordered the aggregates are, the stronger the structural impact of RNA. In addition, an RNA induced reduction of the degree of polymorphism within the aggregate population is obtaine
Periodic lateral superlattice in bonded SrTiO3 SrTiO3 twisted perovskites
Full text linkStacking of freestanding membranes enables the formation of interfaces beyond what can be obtained with classical heteroepitaxy. In particular, twisted interfaces provide unique physical properties not existent in the corresponding individual layers. An ideal twist grain boundary yields an in plane screw dislocation network, assuming sufficiently strong interactions across the interface, for example, via covalent or ionic bonding. Hereby, the distance between dislocation lines, that is the length scale of the Moir pattern, is set by the twist angle between the adjacent crystalline surfaces and the lattice mismatch in case that different materials are placed together. The associated strain gradients of the periodic pattern are especially appealing for oxide based perovskites due to the intricate connection between surface polarization and subtle structural deformations such as the oxygen octahedra tilt. Recently, freestanding oxide perovskites became available via the sacrificial layer approach, opening a pathway toward oxide based Moir materials. Here, we demonstrate efficient bonding of a freestanding SrTiO3 layer to a SrTiO3 single crystal by initially conducting a wafer bonding process at high temperature and only subsequently dissolving the sacrificial layer. We investigate the twisted SrTiO3 SrTiO3 interface with x ray diffraction in grazing incidence geometry and observe clear signatures of a highly periodic lateral superlattice consistent with the formation of a screw dislocation network. Our work demonstrates a robust route for the fabrication of twisted perovskites and their development into a functional material platform with designed strain gradients at the nanoscal
Delving into the effect of ZnO nanoparticles on the chemistry and electronic properties of aminated graphene Ab initio and experimental probing
No full textThe emerging versatile realm of graphene metal oxide nanoparticles NPs composites has boosted the development of energy storage and gas sensing systems. However, with the advancements in deriving composites of more complex designs, the explicit understanding of their physics with respect to chemistry and morphology began to fade. Here, we aspire to hint at the effect of ZnO nanoparticles on aminated graphene, bundling theoretical modeling with thorough experimental examination Transmission electron microscopy, X ray photoelectron, X ray absorption fine structure and valence band photoemission spectroscopies, and temperature dependent sheet resistance measurements . Starting with setting up the framework for modeling the Am ZnO composite with its thorough verification by experimental probing, we stepwise examine the material s properties. The effect of ZnO surface chemistry on bonding, often neglected theoretically, is highlighted by core level spectroscopy. In turn, band structure and charge localization alterations induced by ZnO NPs are pointed out experimentally, supplemented with the developed method for conductivity calculations. Given these results, the role of graphene, NPs, and their interface in chemiresistive signal appearance is further featured. Taken together, our results give a hint at the mechanisms underlying the interaction between the metal oxide NPs and derivatized graphene, advancing the engineering of such composites for practical application
Subnanometer Tracking of the Oxidation State on Co3O4 Nanoparticles by Identical Location Imaging and Spectroscopy
No full textUnderstanding a catalytic reaction requires tools that elucidate the structure of the catalyst surface and subsurface, ideally at atomic resolution and under reaction conditions. Operando electron microscopy meets this requirement in some cases, but fails in others where the required reaction conditions cannot be reached or lead to an unwanted influence of the electron beam on the reactant and catalyst. We introduce ILIAS identical location imaging and spectroscopy in combination with a quasi in situ approach to disentangle the effect of heat and gas on the surface of nanoparticles from the effect of the electron beam. With this approach we allow high temperatures and pressures in any gaseous environment on the one hand, and atomic resolution imaging and spectroscopy on the other. As a proof of concept, we resolve the structural evolution of a Co3O4 spinel catalyst using ILIAS and track the oxidation state across the surface before and after heating in a reductive or oxidative environment. We then titrate the surface of the catalyst using CO as a probe molecule to remove highly active oxygen species formed during the thermal treatment, providing unprecedented insight into the interplay between pretreatment and surface reactivity of Co3O4 nanoparticle
The insight into the biology of five homologous lectins produced by the entomopathogenic bacterium and nematode symbiont Photorhabdus laumondii
No full textPhotorhabdus laumondii is a well known bacterium with a complex life cycle involving mutualism with nematodes of the genus Heterorhabditis and pathogenicity towards insect hosts. It provides an excellent model for studying the diverse roles of lectins, saccharide binding proteins, in both symbiosis and pathogenicity. This study focuses on the seven bladed amp; 946; propeller lectins of P. laumondii PLLs , examining their biochemical properties structure and saccharide specificity and biological functions gene expression, interactions with the nematode symbiont, and the host immune system response . Structural analyses revealed diverse oligomeric states among PLLs and a unique organisation of binding sites not described outside the PLL lectin family. Lectins exhibited high specificity for fucosylated and O methylated saccharides with a significant avidity effect for multivalent ligands. Gene expression analysis across bacterial growth phases revealed that PLLs are predominantly expressed during the exponential phase. Interaction studies with the host immune system demonstrated that PLL5 uniquely induced melanisation in Galleria mellonella hemolymph. Furthermore, PLL2, PLL3, and PLL5 interfered with reactive oxygen species production in human blood cells, indicating their potential role in modulating host immune responses. Biofilm formation assays and binding studies with nematode life stages showed no significant involvement of PLLs in nematode colonization. Our findings highlight the primary role of PLLs in Photorhabdus pathogenicity rather than in symbiosis and offer valuable insight into the fascinating dynamics within the Photorhabdus nematode insect triparted syste