Correlated Diffuse X-ray Scattering from Periodically Nano-Structured Surfaces

Laterally periodic nanostructures were investigated with grazing incidence small angle X-ray scattering. To support an improved reconstruction of nanostructured surface geometries, we investigated the origin of the contributions to the diffuse scattering pattern which is correlated to the surface roughness. Resonant diffuse scattering leads to a palm-like structure of intensity sheets. Dynamic scattering generates the so-called Yoneda band caused by a resonant scatter enhancement at the critical angle of total reflection and higher-order Yoneda bands originating from a subsequent diffraction of the Yoneda enhanced scattering at the grating. Our explanations are supported by modelling using a solver for the time-harmonic Maxwell's equations based on the finite-element method

Clinical, histopathological and molecular features of dedifferentiated melanomas:An EORTC Melanoma Group Retrospective Analysis

PURPOSE: Dedifferentiated melanoma (DedM) poses significant diagnostic challenges. We aimed to investigate the clinical, histopathological and molecular features of DedM. Methylation signature (MS) and copy number profiling (CNP) were carried out in a subgroup of cases.PATIENTS AND METHODS: A retrospective series of 78 DedM tissue samples from 61 patients retrieved from EORTC (European Organisation for Research and Treatment of Cancer) Melanoma Group centres were centrally reviewed. Clinical and histopathological features were retrieved. In a subgroup of patients, genotyping through Infinium Methylation microarray and CNP analysis was carried out.RESULTS: Most patients (60/61) had a metastatic DedM showing most frequently an unclassified pleomorphic, spindle cell, or small round cell morphology akin to undifferentiated soft tissue sarcoma, rarely associated with heterologous elements. Overall, among 20 successfully analysed tissue samples from 16 patients, we found retained melanoma-like MS in only 7 tissue samples while a non-melanoma-like MS was observed in 13 tissue samples. In two patients from whom multiple specimens were analysed, some of the samples had a preserved cutaneous melanoma MS while other specimens exhibited an epigenetic shift towards a mesenchymal/sarcoma-like profile, matching the histological features. In these two patients, CNP was largely identical across all analysed specimens, in line with their common clonal origin, despite significant modification of their epigenome.CONCLUSIONS: Our study further highlights that DedM represents a real diagnostic challenge. While MS and genomic CNP may help pathologists to diagnose DedM, we provide proof-of-concept that dedifferentiation in melanoma is frequently associated with epigenetic modifications.</p

Evidence Map of Pancreatic Surgery-A living systematic review with meta-analyses by the International Study Group of Pancreatic Surgery (ISGPS)

Background: Pancreatic surgery is associated with considerable morbidity and, consequently, offers a large and complex field for research. To prioritize relevant future scientific projects, it is of utmost importance to identify existing evidence and uncover research gaps. Thus, the aim of this project was to create a systematic and living Evidence Map of Pancreatic Surgery. Methods: PubMed, the Cochrane Central Register of Controlled Trials, and Web of Science were systematically searched for all randomized controlled trials and systematic reviews on pancreatic surgery. Outcomes from every existing randomized controlled trial were extracted, and trial quality was assessed. Systematic reviews were used to identify an absence of randomized controlled trials. Randomized controlled trials and systematic reviews on identical subjects were grouped according to research topics. A web-based evidence map modeled after a mind map was created to visualize existing evidence. Meta-analyses of specific outcomes of pancreatic surgery were performed for all research topics with more than 3 randomized controlled trials. For partial pancreatoduodenectomy and distal pancreatectomy, pooled benchmarks for outcomes were calculated with a 99% confidence interval. The evidence map undergoes regular updates. Results: Out of 30,860 articles reviewed, 328 randomized controlled trials on 35,600 patients and 332 systematic reviews were included and grouped into 76 research topics. Most randomized controlled trials were from Europe (46%) and most systematic reviews were from Asia (51%). A living meta-analysis of 21 out of 76 research topics (28%) was performed and included in the web-based evidence map. Evidence gaps were identified in 11 out of 76 research topics (14%). The benchmark for mortality was 2% (99% confidence interval: 1%–2%) for partial pancreatoduodenectomy and <1% (99% confidence interval: 0%–1%) for distal pancreatectomy. The benchmark for overall complications was 53% (99%confidence interval: 46%–61%) for partial pancreatoduodenectomy and 59% (99% confidence interval: 44%–80%) for distal pancreatectomy. Conclusion: The International Study Group of Pancreatic Surgery Evidence Map of Pancreatic Surgery, which is freely accessible via www.evidencemap.surgery and as a mobile phone app, provides a regularly updated overview of the available literature displayed in an intuitive fashion. Clinical decision making and evidence-based patient information are supported by the primary data provided, as well as by living meta-analyses. Researchers can use the systematic literature search and processed data for their own projects, and funding bodies can base their research priorities on evidence gaps that the map uncovers

Li K Emissions Detection In Various Compounds Using A Reflection Zone Plate Spectrometer

International audienceSoft x-ray emission spectroscopy (XES) is a technique used to study the electronic structure of materials. It measures the energy spectrum of emitted x-rays from a sample. It is performed by irradiating the sample with ionizing particles (electrons in our case) and measuring the energy distribution of the x-rays that are subsequently emitted. The emitted x-rays are characteristic of the electronic states of the sample, thus, the presence of an element can be detected and could be also used to perform quantitative analysis.Reflection zone plates (RZP) can be used in XES as a wavelength-dispersive element [1]. They consist of a series of concentric zones, each with a slightly different thickness. When x-rays are incident on the zone plate, the different zones act as diffraction gratings, causing the x-rays to diffract and interfere with one another while focusing them at the same time. They have higher spectral resolution and cover wider energy ranges compared to other optical elements such as periodic multilayers. RZPs allow the reach of energy resolutions as low as 0.49 eV at the Al L2,3 line (around 72 eV) [2]. With parallel detection of x-rays in contrast to conventional wavelength dispersive spectroscopy (WDS) spectrometers with a dispersive crystal (or multilayer) based on Rowland mounting they do not have a scanning mechanism. In this work, we demonstrate the use of a Fresnel (RZP) implemented in an electron microprobe for the detection of Li K (around 50-55 eV) emission in different lithium compounds. Li K emission is a characteristic emission band produced when Li 1s levels are ionized inside the material. However, it can be challenging to detect this emission due to its low fluorescence yield, re-absorption effects, and the presence of other spectral lines in the same energy range. We report on our measurements of the Li K emission bands in several lithium compounds with an RZP spectrometer. Our results demonstrate this approach’s potential for various applications in the field of x-ray spectroscopy.Acknowledgment: This research was funded by Agence Nationale de la Recherche in the framework of the SQLX Project (ANR-20-CE29-0022).References[1]A. Erko et al., Opt. Express, vol. 22, no. 14, p. 16897, Jul. 2014, doi: 10.1364/OE.22.016897.[2]A. Hafner et al., Opt. Express, vol. 23, no. 23, p. 29476, Nov. 2015, doi: 10.1364/OE.23.029476