Search

In this work, a fundamental investigation of an industrial (Cr,Al)N reactive high power pulsed magnetron sputtering (HPPMS) process is presented. The results will be used to improve the coating development for the addressed application, which is the tool coating for plastics processing industry. Substrate-oriented plasma diagnostics and deposition of the (Cr,Al)N coatings were per- formed for a variation of the HPPMS pulse frequency with values from f = 300Hz to f = 2000Hz at constant average power P = 2.5 kW and pulse length ton = 40µs. The plasma was investigated using an oscilloscope, an intensified charge coupled device camera, phase-resolved optical emission spectroscopy, and an energy-dispersive mass spectrometer. The coating properties were determined by means of scanning electron microscopy, glow discharge optical emission spectros- copy, cantilever stress sensors, nanoindentation, and synchrotron X-ray diffraction. Regarding the plasma properties, it was found that the average energy within the plasma is nearly constant for the frequency variation. In contrast, the metal to gas ion flux ratio is changed from JM/JG = 0.51 to JM/JG = 0.10 for increasing frequency. Regarding the coating properties, a structure refinement as well as lower residual stresses, higher universal hardness, and a changing crystal orientation from (111) to (200) were observed at higher frequencies. By correlating the plasma and coating properties, it can be concluded that the change in the gas ion to metal ion flux ratio results in a competitive crystal growth of the film, which results in changing coating properties. [ABSTRACT FROM AUTHOR]

Background: A cornerstone of surgical residency training is an educational program that produces highly skilled and effective surgeons. Training structures are constantly being revised due to evolving program structures, shifting workforces, and variability in the clinical environment. This has resulted in significant heterogeneity in all surgical resident education, training tools utilized, and measures of training efficacy., Methods: We systematically reviewed educational interventions for technical skills in neurosurgery published across PubMed, Embase, and Web of Science over four decades. We extracted general characteristics of each surgical training tool while categorizing educational interventions by modality and neurosurgical application., Results: We identified 626 studies which developed surgical training tools across eight different training modalities: textbooks and literature (11), online resources (53), didactic teaching and one-on-one instruction (7), laboratory courses (50), cadaveric models (63), animal models (47), mixed reality (166), and physical models (229). While publication volume has grown exponentially, a majority of studies were cited with relatively low frequency. Most training programs were published in the development and validation phase with only 2.1% of tools implemented long-term. Each training modality expressed unique strengths and limitations, with limited data reported on the educational impact connected to each training tool., Conclusions: Numerous surgical training tools have been developed and implemented across residency training programs. Though many creative and cutting-edge tools have been devised, evidence supporting educational efficacy and long-term application is lacking. Increased utilization of novel surgical training tools will require validation of metrics used to assess the training outcomes and optimized integration with clinical practice., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Compositionally complex materials such as high-entropy alloys and oxides have the potential to be efficient platforms for catalyst discovery because of the vast chemical space spanned by these novel materials. Identifying the composition of the most active catalyst materials, however, requires unraveling the descriptor-activity relationship, as experimentally screening the multitude of possible element ratios quickly becomes a daunting task. In this work, we show that inferred adsorption energy distributions of *OH and *O on complex solid solution surfaces within the space spanned by the system Ag-Pd-Pt-Ru are coupled to the experimentally observed electrocatalytic performance for the oxygen reduction reaction. In total, the catalytic activity of 1582 alloy compositions is predicted with a cross-validated mean absolute error of 0.042 mA/cm 2 by applying a theory-derived model with only two adjustable parameters. Trends in the discrepancies between predicted electrochemical performance values of the model and the measured values on thin film surfaces subsequently provide insight into the alloys' surface compositions during reaction conditions. Bridging this gap between computationally modeled and experimentally observed catalytic activities, not only reveals insight into the underlying theory of catalysis but also takes a step closer to realizing exploration and exploitation of high-entropy materials., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Polyelemental material systems, specifically high-entropy alloys, promise unprecedented properties. Due to almost unlimited combinatorial possibilities, their exploration and exploitation is hard. This challenge is addressed by co-sputtering combined with shadow masking to produce a multitude of microscale combinatorial libraries in one deposition process. These thin-film composition spreads on the microscale cover unprecedented compositional ranges of high-entropy alloy systems and enable high-throughput characterization of thousands of compositions for electrocatalytic energy conversion reactions using nanoscale scanning electrochemical cell microscopy. The exemplary exploration of the composition space of two high-entropy alloy systems provides electrocatalytic activity maps for hydrogen evolution and oxygen evolution as well as oxygen reduction reactions. Activity optima in the system Ru-Rh-Pd-Ir-Pt are identified, and active noble-metal lean compositions in the system Co-Ni-Mo-Pd-Pt are discovered. This illustrates that the proposed microlibraries are a holistic discovery platform to master the multidimensionality challenge of polyelemental systems., (© 2023 The Authors. Advanced Materials published by Wiley-VCH GmbH.)

The psychological consequences of losing a parent to cancer are unclear. We investigated whether experiencing parental death to cancer before 18 years of age increases the risk of psychotropic medication. We used register data of all children born in Denmark between 1 January 1987 and 31 December 2016 (N = 1,488,846). We assessed rate ratios (RRs) with 95% confidence intervals (CIs) for first redeemed prescription of antidepressants, anxiolytics and hypnotics according to parental death status using Poisson multi-state models. We further examined whether the associations differed according to the gender of the deceased parent, child's age at the time of death or the parental length of illness. Cancer-bereaved children had a significantly increased risk of first prescription of psychotropic medication (rate ratio, RR 1.22, 95% confidence interval, CI 1.10-1.34 for males; RR 1.18, 95% CI 1.09-1.28 for females). Associations were strongest if the parent had the same sex as the child and if the parent died within one year of diagnosis. The risk was highest during the first six months after the loss (RR 2.35, 95% confidence interval, CI 1.48-3.73 for males; RR 1.81, 95% CI 1.17-2.80 for females). Children who lose a parent to cancer, particularly in cases when the disease progressed quickly, may need extra psychological support, especially during the first six months after the death., (© 2021. Springer-Verlag GmbH Germany, part of Springer Nature.)

Active, selective and stable catalysts are imperative for sustainable energy conversion, and engineering materials with such properties are highly desired. High-entropy alloys (HEAs) offer a vast compositional space for tuning such properties. Too vast, however, to traverse without the proper tools. Here, we report the use of Bayesian optimization on a model based on density functional theory (DFT) to predict the most active compositions for the electrochemical oxygen reduction reaction (ORR) with the least possible number of sampled compositions for the two HEAs Ag-Ir-Pd-Pt-Ru and Ir-Pd-Pt-Rh-Ru. The discovered optima are then scrutinized with DFT and subjected to experimental validation where optimal catalytic activities are verified for Ag-Pd, Ir-Pt, and Pd-Ru binary alloys. This study offers insight into the number of experiments needed for optimizing the vast compositional space of multimetallic alloys which has been determined to be on the order of 50 for ORR on these HEAs., (© 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

The discovery of new structural and functional materials is driven by phase identification, often using X-ray diffraction (XRD). Automation has accelerated the rate of XRD measurements, greatly outpacing XRD analysis techniques that remain manual, time-consuming, error-prone and impossible to scale. With the advent of autonomous robotic scientists or self-driving laboratories, contemporary techniques prohibit the integration of XRD. Here, we describe a computer program for the autonomous characterization of XRD data, driven by artificial intelligence (AI), for the discovery of new materials. Starting from structural databases, we train an ensemble model using a physically accurate synthetic dataset, which outputs probabilistic classifications-rather than absolutes-to overcome the overconfidence in traditional neural networks. This AI agent behaves as a companion to the researcher, improving accuracy and offering substantial time savings. It is demonstrated on a diverse set of organic and inorganic materials characterization challenges. This method is directly applicable to inverse design approaches and robotic discovery systems, and can be immediately considered for other forms of characterization such as spectroscopy and the pair distribution function., (© 2021. This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply.)

Thin-film continuous composition spreads of Fe-Co-O were fabricated by reactive cosputtering from elemental Fe and Co targets in reactive Ar/O 2 atmosphere using deposition temperatures ranging from 300 to 700 °C. Fused silica and platinized Si/SiO 2 strips were used as substrates. Ti and Ta were investigated as adhesion layer for Pt and the fabrication of the Fe-Co-O films. The thin-film composition spreads were characterized by high-throughput electron-dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, and optical transmission spectroscopy. The Fe-content ranged from 28 to 72 at. %. The spinel phases Fe 2 CoO 4 and FeCo 2 O 4 could be synthesized and stabilized at all deposition temperatures with a continuous variation in spinel composition in between. The dependence of the film surface microstructure on the deposition temperature and the composition was mapped. Moreover, the band gap values, ranging from 2.41 eV for FeCo 2 O 4 to 2.74 eV for Fe 2 CoO 4 , show a continuous variation with the composition.

Research data management is a major necessity for the digital transformation in material science. Material science is multifaceted and experimental data, especially, is highly diverse. We demonstrate an adjustable approach to a group level data management based on a customizable document management software. Our solution is to continuously transform data management workflows from generalized to specialized data management. We start up fast with a relatively unregulated base setting and adapt continuously over the period of use to transform more and more data procedures into specialized data management workflows. By continuous adaptation and integration of analysis workflows and metadata schemes, the amount and the quality of the data improves. As an example of this process, in a period of 36 months, data on over 1800 samples, mainly materials libraries with hundreds of individual samples, were collected. The research data management system now contains over 1700 deposition processes and more than 4000 characterization documents. From initially mainly user-defined data input, an increased number of specialized data processing workflows was developed allowing the collection of more specialized, quality-assured data sets.

Multiple principal element alloys, also often referred to as compositionally complex alloys or high entropy alloys, present extreme challenges to characterize. They show a vast, multidimensional composition space that merits detailed investigation and optimization to identify compositions and to map the composition ranges where useful properties are maintained. Combinatorial thin film material libraries are a cost-effective and efficient way to create directly comparable, controlled composition variations. Characterizing them comes with its own challenges, including the need for high-speed, automated measurements of dozens to hundreds or more compositions to be screened. By selecting an appropriate thin film morphology through predictable control of critical deposition parameters, representative measured values can be obtained with less scatter, i.e., requiring fewer measurement repetitions for each particular composition. In the present study, equiatomic CoCrFeNi was grown by magnetron sputtering in different locations in the structure zone diagram applied to multinary element alloys, followed by microstructural and morphological characterizations. Increasing the energy input to the deposition process by increased temperature and adding high-power impulse magnetron sputtering (HiPIMS) plasma generators led to denser, more homogeneous morphologies with smoother surfaces until recrystallization and grain boundary grooving began. Growth at 300 °C, even without the extra particle energy input of HiPIMS generators, led to consistently repeatable nanoindentation load-displacement curves and the resulting hardness and Young's modulus values.

Cr-Al-N thin film materials libraries were synthesized by combinatorial reactive high power impulse magnetron sputtering (HiPIMS). Different HiPIMS repetition frequencies and peak power densities were applied altering the ion to growth flux ratio. Moreover, time-resolved ion energy distribution functions were measured with a retarding field energy analyzer (RFEA). The plasma properties were measured during the growth of films with different compositions within the materials library and correlated to the resulting film properties such as phase, grain size, texture, indentation modulus, indentation hardness, and residual stress. The influence of the ion to growth flux ratio on the film properties was most significant for films with high Al-content ( x Al = 50 at. %). X-ray diffraction with a 2D detector revealed hcp-AlN precipitation starting from Al-concentration x Al ≥ 50 at. %. This precipitation might be related to the kinetically enhanced adatom mobility for a high ratio of ions per deposited atoms, leading to strong intermixing of the deposited species. A structure zone transition, induced by composition and flux ratio J I / J G , from zone T to zone Ic structure was observed which hints toward the conclusion that the combination of increasing flux ratio and Al-concentration lead to opposing trends regarding the increase in homologous temperature.

A study on the plasma-enhanced atomic layer deposition of amorphous inorganic oxides SiO 2 and Al 2 O 3 on polypropylene (PP) was carried out with respect to growth taking place at the interface of the polymer substrate and the thin film employing in situ quartz-crystal microbalance (QCM) experiments. A model layer of spin-coated PP (scPP) was deposited on QCM crystals prior to depositions to allow a transfer of findings from QCM studies to industrially applied PP foil. The influence of precursor choice (trimethylaluminum (TMA) vs [3-(dimethylamino)propyl]-dimethyl aluminum (DMAD)) and of plasma pretreatment on the monitored QCM response was investigated. Furthermore, dyads of SiO 2 /Al 2 O 3 , using different Al precursors for the Al 2 O 3 thin-film deposition, were investigated regarding their barrier performance. Although the growth of SiO 2 and Al 2 O 3 from TMA on scPP is significantly hindered if no oxygen plasma pretreatment is applied to the scPP prior to depositions, the DMAD process was found to yield comparable Al 2 O 3 growth directly on scPP similar to that found on a bare QCM crystal. From this, the interface formed between the Al 2 O 3 and the PP substrate is suggested to be different for the two precursors TMA and DMAD due to different growth modes. Furthermore, the residual stress of the thin films influences the barrier properties of SiO 2 /Al 2 O 3 dyads. Dyads composed of 5 nm Al 2 O 3 (DMAD) + 5 nm SiO 2 exhibit an oxygen transmission rate (OTR) of 57.4 cm 3 m -2 day -1 , which correlates with a barrier improvement factor of 24 against 5 when Al 2 O 3 from TMA is applied.

We present a case of aortic intramural hematoma (IMH) in an elderly woman who presented with sudden onset of mid-scapular pain. The patient underwent a series of multimodality imaging studies before the diagnosis of IMH was evident by cardiovascular magnetic resonance, which is rapidly becoming the gold standard in the evaluation of acute aortic disease due to its high spatial resolution and ability to characterize tissue composition. Early diagnosis and prompt treatment is critical in improving the outcome of patients with IMH.