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Abstract: The high pulse intensity and repetition rate of the European X-ray Free-Electron Laser (EuXFEL) provide superior temporal resolution compared with other X-ray sources. In combination with MHz X-ray microscopy techniques, it offers a unique opportunity to achieve superior contrast and spatial resolution in applications demanding high temporal resolution. In both live visualization and offline data analysis for microscopy experiments, baseline normalization is essential for further processing steps such as phase retrieval and modal decomposition. In addition, access to normalized projections during data acquisition can play an important role in decision-making and improve the quality of the data. However, the stochastic nature of X-ray free-electron laser sources hinders the use of standard flat-field normalization methods during MHz X-ray microscopy experiments. Here, an online (i.e. near real-time) dynamic flat-field correction method based on principal component analysis of dynamically evolving flat-field images is presented. The method is used for the normalization of individual X-ray projections and has been implemented as a near real-time analysis tool at the Single Particles, Clusters, and Biomolecules and Serial Femtosecond Crystallography (SPB/SFX) instrument of EuXFEL.

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Abstract: Purpose / Aim: Dentine hypersensitivity (DH) is a commonly occurring dental condition where sharp pain derived from exposed dentine in response to stimuli that cannot be ascribed to any other dental diseases. It is highly prevalent affecting up to 69% of the UK population and has a significant impact on the quality of life. Bioactive glasses that degrade in oral environment and form apatite are thought to be beneficial in occluding the exposed open dentine tubules and have been introduced to toothpastes, e.g. Novamin® (45S5 Bioglass) for Sensodyne by GSK, fluoride containing bioactive glass for BioMin® F by BioMin Technologies Ltd. Post-mortem characterisations evidenced tubule occlusion (Fig.1) but failed in providing dynamic history. Therefore, this study aimed to monitor dentine tubule occlusion with bioactive glasses using an operando time-lapse X-ray diffraction tomography experiment. Materials & Methods: Disinfected Teeth (collected under REC reference 16/SW/0220) were sectioned mesio-distally into discs approximately 500 μm thick using a precision diamond saw, polished down to 300 μm manually. Matchstick specimens (5 mm length x 3 mm width) prepared were brushed for 2 mins with bioactive glasses pastes, housed in a modified Eppendorf tube and positioned on the tomography stage of the Dual Imaging and Diffraction (DIAD) beamline at Diamond Light Source (UK’s national synchrotron). A baseline X-ray tomography (pink beam, 0-180°, detector exposure of 0.01 and 5,000 projections) and X-ray diffraction mapping (matrix scan with 10x10 points, 20 s exposure) were collected before artificial saliva was introduced. Time-lapse X-ray tomography and X-ray diffraction mapping using the same parameters as baseline scan were carried out consecutively for 8 h allowing the visualisation of tubule occlusion and changes of mineral density as well as monitor the phase evolution from glass to apatite. Artificial saliva was manually replenished. Monochromatic beam with an energy of 20 keV was used and calibrations were performed. Results: The collected tomography data allow visualisation of dentine tubule occlusion showing improved occlusion with time. 2D XRD data provide qualitative and quantitative information relates to glass dissolution and apatite formation as a function of time. Conclusions: The Dual Imaging and Diffraction (DIAD) beamline correlates X-ray tomography and X-ray diffraction mapping offers the opportunity to study dentine occlusion by bioactive glasses in a time evolving manner that is not available via other techniques. Although in vitro but clinically relevant. The results will potentially provide a guidance for optimising and designing products for dentine tubule occlusion/treating dentine hypersensitivity – one of the most prevalent global diseases with healthy ageing.

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Abstract: In situations where the stereoregularity of the polymer chains permits, crystals can form in synthetic or natural polymers. These crystals have an immense impact on the properties of the polymeric material. Typically polymers crystallized from a quiescent melt form spherulites, but where the melt exhibits a level of anisotropy, the crystalline morphology, is quite different to the spherulitic structure, although it may well contain chain-folded lamellar crystals. We consider a number of different systems in which the anisotropy has developed in different ways. Despite these differences, there are strong features in common within the semi-crystalline polymer morphology. We consider the strain-induced crystallization in deformed natural rubber, in sheared melts containing both self-assembling nanoparticles and engineered nanoparticles, and during extrusion as part of fused granular deposition-based 3D printing.

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Abstract: Among the functional materials suitable for the realization of solar cells and light emission diodes (LEDs), perovskites, especially fully inorganic perovskites, are considered among the most promising. CsPbBr3 is the most studied due to its favorable band gap value and stability under mild atmospheric conditions: moisture and UV visible radiation exposure. Using this material, highly efficient thin film solar cells have been produced at the lab scale, and researchers aim to scale the process up to the industrial level. Here, ultrathin films of CsPbBr3 were obtained by magnetron sputtering, and the texture and morphology of the deposited films were evaluated as a function of their thickness and the substrate's nature. The obtained films are composed of highly textured structures of submicrometric crystals homogeneously distributed all over the surface. Finally, the texture decreases as the deposit thickness increases.

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Abstract: The aTfaRel2/faRel2 operon from Coprobacillus sp. D7 encodes a bicistronic type II toxin–antitoxin (TA) module. The FaRel2 toxin is a toxic small alarmone synthetase (toxSAS) that inhibits translation through the pyrophosphorylation of uncharged tRNAs at the 3′-CCA end. The toxin is neutralized by the antitoxin ATfaRel2 through the formation of an inactive TA complex. Here, the production, biophysical analysis and crystallization of ATfaRel2 and FaRel2 as well as of the ATfaRel2–FaRel2 complex are reported. ATfaRel2 is monomeric in solution. The antitoxin crystallized in space group P21212 with unit-cell parameters a = 53.3, b = 34.2, c = 37.6 Å, and the best crystal diffracted to a resolution of 1.24 Å. Crystals of FaRel2 in complex with APCPP, a non­hydrolysable ATP analogue, belonged to space group P21, with unit-cell parameters a = 31.5, b = 60.6, c = 177.2 Å, β = 90.6°, and diffracted to 2.6 Å resolution. The ATfaRel2–FaRel2Y128F complex forms a heterotetramer in solution composed of two toxins and two antitoxins. This complex crystallized in two space groups: F4132, with unit-cell parameters a = b = c = 227.1 Å, and P212121, with unit-cell parameters a = 51.7, b = 106.2, c = 135.1 Å. The crystals diffracted to 1.98 and 2.1 Å resolution, respectively.