In situ Investigation during Low Pressure Carburizing by Means of Synchrotron X-ray Diffraction*

In situ X-ray diffraction investigations during low pressure carburizing (LPC) processes were performed with a specially developed process chamber at the German Electron Synchrotron Facility (DESY) in Hamburg, Germany. Carbon saturation in austenite was reached in less than 20 seconds for all processes with different parameters and carbides formed at the surface. Therefore, the direct contribution of carbon donor gas to the carbon profile after 20 seconds was reduced to very low levels. After that point, further supply of carbon donor gas increased the amount of carbides formed at the surface, which will contribute to the carbon profile indirectly by dissolution in the following diffusion steps. During quenching, martensite at higher temperatures had a lower c/a ratio than later formed ones. This difference is credited to self-tempering effects and reordering of carbon atoms within the martensite lattice.

Pulmonary acini exhibit complex changes during postnatal rat lung development

Pulmonary acini represent the functional gas-exchanging units of the lung. Due to technical limitations, individual acini cannot be identified on microscopic lung sections. To overcome these limitations, we imaged the right lower lobes of instillation-fixed rat lungs from postnatal days P4, P10, P21, and P60 at the TOMCAT beamline of the Swiss Light Source synchrotron facility at a voxel size of 1.48 μm. Individual acini were segmented from the three-dimensional data by closing the airways at the transition from conducting to gas exchanging airways. For a subset of acini (N = 268), we followed the acinar development by stereologically assessing their volume and their number of alveoli. We found that the mean volume of the acini increases 23 times during the observed time-frame. The coefficients of variation dropped from 1.26 to 0.49 and the difference between the mean volumes of the fraction of the 20% smallest to the 20% largest acini decreased from a factor of 27.26 (day 4) to a factor of 4.07 (day 60), i.e. shows a smaller dispersion at later time points. The acinar volumes show a large variation early in lung development and homogenize during maturation of the lung by reducing their size distribution by a factor of 7 until adulthood. The homogenization of the acinar sizes hints at an optimization of the gas-exchange region in the lungs of adult animals and that acini of different size are not evenly distributed in the lungs. This likely leads to more homogeneous ventilation at later stages in lung development.

The first infrared beamline at the Middle East SESAME synchrotron facility

SESAME (Synchrotron-light for Experimental Science and Applications in the Middle East) is the only synchrotron light facility in the Middle East and neighboring regions, officially opened in 2017. Among the identification and construction of the first operational beamlines, infrared spectromicroscopy was selected as one of the two beamlines to be opened to the general users' program (the so-called Day-1 beamlines). Being one of the most demanded techniques by various scientific communities in the Middle East, the beamline has been designed and implemented in the framework of a collaboration agreement with the French synchrotron facility, SOLEIL. The design, construction and initial performances of the IR beamline (D02-IR), nowadays operational, are reported.

Performance and characterization of the FinEstBeAMS beamline at the MAX IV Laboratory

FinEstBeAMS (Finnish–Estonian Beamline for Atmospheric and Materials Sciences) is a multidisciplinary beamline constructed at the 1.5 GeV storage ring of the MAX IV synchrotron facility in Lund, Sweden. The beamline covers an extremely wide photon energy range, 4.5–1300 eV, by utilizing a single elliptically polarizing undulator as a radiation source and a single grazing-incidence plane grating monochromator to disperse the radiation. At photon energies below 70 eV the beamline operation relies on the use of optical and thin-film filters to remove higher-order components from the monochromated radiation. This paper discusses the performance of the beamline, examining such characteristics as the quality of the gratings, photon energy calibration, photon energy resolution, available photon flux, polarization quality and focal spot size.

Electrochemical feedback on strain dynamics in noble metal nanocatalysts

The theoretical design of effective metal electrocatalysts for energy conversion and storage devices relies on the structure sensitivity of electrochemical processes to their catalyst materials, assuming the structural integrity during operation. However, theoretical predictions do not necessarily match practical performance. Here, by using high-energy X-ray diffraction from the new Extremely Brilliant Source of the European Radiation Synchrotron Facility (ESRF-EBS) on device-relevant Pd and Pt nanocatalysts during cyclic voltammetry experiments in liquid electrolyte, we quantitatively reveal how different electrochemical processes permanently affect the bulk microstructure of nanocatalysts in a distinctive fashion. The reported structural insights provide experimental access to reactivity descriptors such as adsorption and absorption trends operando. The ease and power of such an experimental approach at new and future beamlines is foreseen to guide computational model description of practical nanomaterials in electrochemical environment while providing a discovery platform toward the study of nanocatalysts encompassing a large variety of applications.

Perspectives for microbeam irradiation at the SYRMEP beamline

It has been shown previously both in vitro and in vivo that microbeam irradiation (MBI) can control malignant tumour cells more effectively than the clinically established concepts of broad beam irradiation. With the aim to extend the international capacity for microbeam research, the first MBI experiment at the biomedical beamline SYRMEP of the Italian synchrotron facility ELETTRA has been conducted. Using a multislit collimator produced by the company TECOMET, arrays of quasi-parallel microbeams were successfully generated with a beam width of 50 µm and a centre-to-centre distance of 400 µm. Murine melanoma cell cultures were irradiated with a target dose of approximately 65 Gy at a mean photon energy of ∼30 keV with a dose rate of 70 Gy s−1 and a peak-to-valley dose of ∼123. This work demonstrated a melanoma cell reduction of approximately 80% after MBI. It is suggested that, while a high energy is essential to achieve high dose rates in order to deposit high treatment doses in a short time in a deep-seated target, for in vitro studies and for the treatment of superficial tumours a spectrum in the lower energy range might be equally suitable or even advantageous.

Micro-XRF study of the troodontid dinosaur Jianianhualong tengi reveals new biological and taphonomical signals

Jianianhualong tengi is a key taxon for understanding the evolution of pennaceous feathers as well as troodontid theropods, and it is known by only the holotype, which was recovered from the Lower Cretaceous Yixian Formation of western Liaoning, China. Here, we carried out a large-area micro-X-Ray fluorescence (micro-XRF) analysis on the holotypic specimen of Jianianhualong tengi via a Brucker M6 Jetstream mobile XRF scanner. The elemental distribution measurements of the specimen show an enrichment of typical bones couponing elements such as S, P and Ca allowing to visualize the fossil structure. Additionally, to this, the bones are enriched in several heavier elements such as Sr, Th, Y and Ce over the surrounding rocks. The enrichment is most likely associated to secondary mineralization and the phosphates from the bones. Interestingly the plumage shape correlates with an enrichment in elements such as Cu, Ni and Ti, consistent with a previous study [1] on Archaeopteryx using synchrotron imaging. The analysis presented here provide new biological and taphonomic information of this fossil. An in-situ and nondestructive micro-XRF analysis is currently the most ideal way to map the chemistry of fossils, so far this is manly restricted to small samples. Larger samples usually required a synchrotron facility for analysis. Our study demonstrated that laboratory-based large-area micro-XRF scanner can provides a practical tool for the study of large large-sized specimens allowing collect full chemical data for a better understanding of evolutionary and taphonomic processes.