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"X radiation"
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The Race to X-ray Microbeam and Nanobeam Science
X-ray microbeams are an emerging characterization tool with broad implications for science, ranging from materials structure and dynamics, to geophysics and environmental science, to biophysics and protein crystallography. We describe how submicrometer hard x-ray beams with the ability to penetrate tens to hundreds of micrometers into most materials and with the ability to determine local composition, chemistry, and (crystal) structure can characterize buried sample volumes and small samples in their natural or extreme environments. Beams less than 10 nanometers have already been demonstrated, and the practical limit for hard x-ray beam size, the limit to trace-element sensitivity, and the ultimate limitations associated with near-atomic structure determinations are the subject of ongoing research.
Journal Article
Spontaneous and X-ray-Triggered Crystallization at Long Range in Self-Assembling Filament Networks
We report here crystallization at long range in networks of like-charge supramolecular peptide filaments mediated by repulsive forces. The crystallization is spontaneous beyond a given concentration of the molecules that form the filaments but can be triggered by x-rays at lower concentrations. The crystalline domains formed by x-ray irradiation, with interfilament separations of up to 320 angstroms, can be stable for hours after the beam is turned off, and ions that screen charges on the filaments suppress ordering. We hypothesize that the stability of crystalline domains emerges from a balance of repulsive tensions linked to native or x-ray-induced charges and the mechanical compressive entrapment of filaments within a network. Similar phenomena may occur naturally in the cytoskeleton of cells and, if induced externally in biological or artificial systems, lead to possible biomedical and lithographic functions.
Journal Article
Synchrotron radiation X‐ray imaging with large field of view and high resolution using micro‐scanning method
In synchrotron radiation X‐ray imaging, the imaging field of view and spatial resolution are mutually restricted, which makes it impossible to have both a large field of view and high resolution when carrying out experiments. Constructing an oversampled image through the micro‐scanning method and using the deconvolution algorithm to eliminate the point spread function introduced by pixel overlap can increase the resolution under a fixed imaging field of view, thereby improving the ratio of the field of view to the spatial resolution. In this paper, numerical simulation and synchrotron radiation experiments are carried out with a different number of micro‐scanning steps. In numerical simulation experiments only affected by the image pixel size, as the number of micro‐scanning steps increases, the ability of the oversampled image with deconvolution to improve the resolution is stronger. The achievable resolution of the oversampled image with deconvolution is basically the same as that of the sample image. In the synchrotron radiation experiments, the resolution of the oversampled image with deconvolution in the 2 × 2 mode is significantly improved. However, as the number of micro‐scanning steps increases, the resolution improvement is limited, or even no longer improved. Finally, by analyzing the results of numerical simulation and synchrotron radiation experiments, three factors (four other factors affecting the resolution besides the camera resolution, translational accuracy of micro‐scanning, and the signal‐to‐noise ratio of projections) affecting the micro‐scanning method are proposed and verified by experiments. In synchrotron radiation X‐ray imaging, the spatial resolution under a fixed field of view is improved using the micro‐scanning method.
Journal Article
Ultrafast Bond Softening in Bismuth: Mapping a Solid's Interatomic Potential with X-rays
Intense femtosecond laser excitation can produce transient states of matter that would otherwise be inaccessible to laboratory investigation. At high excitation densities, the interatomic forces that bind solids and determine many of their properties can be substantially altered. Here, we present the detailed mapping of the carrier density-dependent interatomic potential of bismuth approaching a solid-solid phase transition. Our experiments combine stroboscopic techniques that use a high-brightness linear electron accelerator-based x-ray source with pulse-by-pulse timing reconstruction for femtosecond resolution, allowing quantitative characterization of the interatomic potential energy surface of the highly excited solid.
Journal Article
Application of Synchrotron Radiation Based X‐Ray Diffraction in Zeolite Research: Advanced Analysis from Atomic Structure to Dynamic Behavior
Zeolites, as crystalline materials with regular pore channels, are widely utilized in energy, environmental, and advanced manufacturing sectors. Characterizing zeolites is crucial for understanding their structure and properties, which are essential for various applications. Synchrotron Radiation‐based X‐ray Diffraction (SR‐XRD) has become an advanced tool in zeolite research, providing higher resolution, faster scans, and more precise structural information than laboratory X‐ray diffraction methods. This technique allows for detailed studies, from atomic structures to dynamic behaviors, particularly in understanding structural evolution during synthesis and monitoring changes in the framework during reactions. Moreover, SR‐XRD has made significant contributions to catalytic research by revealing structural alterations during catalytic processes and identifying active sites. However, SR‐XRD still faces challenges in data interpretation and other technological limitations. To overcome these, integrating SR‐XRD with other techniques and using AI‐assisted analysis are expected to further advance zeolite characterization and catalytic research. Synchrotron Radiation‐based X‐ray Diffraction (SR‐XRD) offers high‐resolution insights and real‐time monitoring of zeolite synthesis, structural transformations, and catalytic reactions, advancing zeolite‐based catalyst development. However, challenges such as data interpretation and technological limitations remain. Combining SR‐XRD with other techniques and AI‐assisted analysis can overcome these issues and accelerate research in zeolite and catalytic studies.
Journal Article
Elemental analysis and imaging of sunscreen fingermarks by X-ray fluorescence
Chemical composition in fingermarks could provide useful information for forensic studies and applications. Here, we evaluate the feasibility of analysis and imaging of fingermarks via elements by synchrotron radiation X-ray fluorescence (SRXRF) and commercial X-ray fluorescence (XRF). As a proof of concept, we chose four brands of sunscreens to make fingermarks on different substrates, including plastic film, glass, paper, and silicon wafer. We obtained an evident image of fingermarks via zinc and titanium by XRF methods. In addition, the ratios of element concentrations in sunscreen fingermarks were obtained, which were in accordance with the results obtained by acid digestion and ICP-OES analysis. In comparison, commercial XRF offers the most advantages in terms of non-destructive detection, easy accessibility, fast element images, and broad applicability. The possibility to acquire fingermark images simultaneously with element information opens up new avenues for forensic science.
Journal Article
The endothelium in seeds of early angiosperms
Studies of Cretaceous age mesofossil floras – assemblages of small carbonaceous plant fossils isolated from poorly consolidated sediments – have provided a wealth of new insights into the early fossil history of angiosperms (for references, see Friis et al ., 2011). The fossils recovered from such mesofloras include well‐preserved flowers, fruits and seeds that can be compared in detail with those of living plants to provide an integrated picture of early angiosperm evolution. Data from mesofossil floras have also provided many of the fossil calibrations used to model the age of different angiosperm clades based on molecular data (Magallón & Sanderson, 2005; Beaulieu et al ., 2015; Magallón et al ., 2015). From the Early Cretaceous these kinds of fossils have so far only been discovered in deposits from Portugal and eastern North America, where they are sometimes abundant, and often have an exquisite preservation of cellular details.
Journal Article
Protection from radiation-induced apoptosis by the radioprotector amifostine (WR-2721) is radiation dose dependent
The radioprotective agent amifostine is a free radical scavenger that can protect cells from the damaging effects of ionising radiation when administered prior to radiation exposure. However, amifostine has also been shown to protect cells from chromosomal mutations when administered after radiation exposure. As apoptosis is a common mechanism by which cells with mutations are removed from the cell population, we investigated whether amifostine stimulates apoptosis when administered after radiation exposure. We chose to study a relatively low dose which is the maximum radiation dose for radiation emergency workers (0.25 Gy) and a high dose relevant to radiotherapy exposures (6 Gy). Mice were administered 400 mg/kg amifostine 30 min before, or 3 h after, whole-body irradiation with 0.25 or 6 Gy X-rays and apoptosis was analysed 3 or 7 h later in spleen and bone marrow. We observed a significant increase in radiation-induced apoptosis in the spleen of mice when amifostine was administered before or after 0.25 Gy X-rays. In contrast, when a high dose of radiation was used (6 Gy), amifostine caused a reduction in radiation-induced apoptosis 3 h post-irradiation in spleen and bone marrow similar to previously published studies. This is the first study to investigate the effect of amifostine on radiation-induced apoptosis at a relatively low radiation dose and the first to demonstrate that while amifostine can reduce apoptosis from high doses of radiation, it does not mediate the same effect in response to low-dose exposures. These results suggest that there may be a dose threshold at which amifostine protects from radiation-induced apoptosis and highlight the importance of examining a range of radiation doses and timepoints.
Journal Article
Tanispermum, a new genus of hemi-orthotropous to hemi-anatropous angiosperm seeds from the Early Cretaceous of eastern North America
Premise of the Study Exotestal seeds with characters that indicate relationship to extant Austrobaileyales and Nymphaeales are abundant in Early Cretaceous sediments from Portugal and eastern North America, but their variety and unique features provide evidence of extensive extinct diversity among early angiosperms. Methods The fossils were extracted from Early Cretaceous sediments from Virginia and Maryland, United States, by sieving in water. After cleaning with HF, HCl and water, they were examined using SEM and SRXTM and compared to seeds of extant and fossil angiosperms. Key Results A new genus, Tanispermum gen. nov., with four species (T. hopewellense sp. nov., T. marylandense sp. nov., T. drewriense sp. nov., and T. antiquum sp. nov.) is recognized. Relationship with extant Austrobaileyales and Nymphaeales is indicated by an exotesta of tall palisade sclerenchyma with undulate anticlinal walls forming a jigsaw puzzle‐like surface pattern. However, seeds of Tanispermum differ from those of Austrobaileyales and Nymphaeales in their hemi‐orthotropous–hemi‐anatropous organization. Attempts to place Tanispermum in a phylogenetic context confront a variety of problems, including lack of information on other parts of these extinct plants. Conclusions The discovery highlights the extent to which the morphology of extant angiosperms is not representative of the diversity that once existed among early‐diverging members of the group. The relictual nature of extant taxa near the base of the angiosperm tree greatly complicates the reconstruction of ancestral character states and emphasizes the need for focused paleobotanical studies to elucidate the extinct diversity that existed early in angiosperm evolution.
Journal Article