Microstructural Transitions during Powder Metallurgical Processing of Solute Stabilized Nanostructured Tungsten Alloys

Exploiting grain boundary engineering in the design of alloys for extreme environments provides a promising pathway for enhancing performance relative to coarse-grained counterparts. Due to its attractive properties as a plasma facing material for fusion devices, tungsten presents an opportunity to exploit this approach in addressing the significant materials challenges imposed by the fusion environment. Here, we employ a ternary alloy design approach for stabilizing W against recrystallization and grain growth while simultaneously enhancing its manufacturability through powder metallurgical processing. Mechanical alloying and grain refinement in W-10 at.% Ti-(10,20) at.% Cr alloys are accomplished through high-energy ball milling with transitions in the microstructure mapped as a function of milling time. We demonstrate the multi-modal nature of the resulting nanocrystalline grain structure and its stability up to 1300 °C with the coarser grain size population correlated to transitions in crystallographic texture that result from the preferred slip systems in BCC W. Field-assisted sintering is employed to consolidate the alloy powders into bulk samples, which, due to the deliberately designed compositional features, are shown to retain ultrafine grain structures despite the presence of minor carbides formed during sintering due to carbon impurities in the ball-milled powders.

A Genomic Snapshot of the SARS-CoV-2 Pandemic in the Balearic Islands

Objective: To analyze the SARS-CoV-2 genomic epidemiology in the Balearic Islands, a unique setting in which the course of the pandemic has been influenced by a complex interplay between insularity, severe social restrictions and tourism travels.Methods: Since the onset of the pandemic, more than 2,700 SARS-CoV-2 positive respiratory samples have been randomly selected and sequenced in the Balearic Islands. Genetic diversity of circulating variants was assessed by lineage assignment of consensus whole genome sequences with PANGOLIN and investigation of additional spike mutations.Results: Consensus sequences were assigned to 46 different PANGO lineages and 75% of genomes were classified within a VOC, VUI, or VUM variant according to the WHO definitions. Highest genetic diversity was documented in the island of Majorca (42 different lineages detected). Globally, lineages B.1.1.7 and B.1.617.2/AY.X were identified as the 2 major lineages circulating in the Balearic Islands during the pandemic, distantly followed by lineages B.1.177/B.1.177.X. However, in Ibiza/Formentera lineage distribution was slightly different and lineage B.1.221 was the third most prevalent. Temporal distribution analysis showed that B.1 and B.1.5 lineages dominated the first epidemic wave, lineage B.1.177 dominated the second and third, and lineage B.1.617.2 the fourth. Of note, lineage B.1.1.7 became the most prevalent circulating lineage during first half of 2021; however, it was not associated with an increased in COVID-19 cases likely due to severe social restrictions and limited travels. Additional spike mutations were rarely documented with the exception of mutation S:Q613H which has been detected in several genomes (n = 25) since July 2021.Conclusion: Virus evolution, mainly driven by the acquisition and selection of spike substitutions conferring biological advantages, social restrictions, and size population are apparently key factors for explaining the epidemic patterns registered in the Balearic Islands.

Latin American Small and Medium-Sized Enterprises: A Historical Perspective

This special issue seeks to appreciate the long-term study of SMEs as key players in the Latin American economies, with contributions on six countries: Mexico, Brazil, Argentina, Ecuador, Bolivia, and Chile. This is a representative sample of the Latin American subcontinent’s diversity when it comes to economy size, population, and inequality index. The articles presented spot key topics in the study of Latin American SMEs. This introduction focus on three central issues that arise from those articles: the role of public policies in SME emergence and development, the strategies pursued by these firms to adapt to environment changes, and the links between informality and SME creation.

Accuracy and precision of non-invasive continuous haemoglobin concentration monitoring in diabetic patients

Background Accuracy and precision of non-invasive continuous haemoglobin concentration (SpHb) provided by Masimo device in diabetic patients is poorly studied. This retrospective analysis aimed to provide data on SpHb accuracy and precision in diabetic patients. Results The sample size population consisted of 14 patients, with 56 SpHb/Lab data pairs. Lab value showed a mean ± standard deviation (SD) of 13.2 ± 1.2 g/dL, whilst SpHb showed a mean ± SD of 11.8 ± 1.1 g/dL. Linear regression analysis between Lab/SpHb data pairs showed a r of 0.8960 (CI95% 0.8281-0.9379, p value < 0.0001). SpHb underestimated the real Hb values provided by Lab. Bland-Altman analysis showed that SpHb accuracy was −1.37 g/dL (CI95% −1.51 to −1.22 g/dL, p value < 0.0001), precision of 0.55 g/dL, lower LOA −2.45 g/dL (CI95% −2.71 to −2.20 g/dL) and upper LOA −0.28 g/dL (CI95% −0.53 to −0.02 g/dL). Conclusions For the first time, we provided data on SpHb accuracy and precision in the diabetic population. SpHb showed a high correlation coefficient when compared with Lab values, but the wide LOA limits its accuracy.

Demographic Theory and Population Ethics – Relationships between Population Size and Population Growth

Demographic theory aims at explaining how population systems regulate themselves given available resources. Population ethics is concerned with demography in the sense that the analytical objects of interest are births, deaths, and populations. However, demographic theory which explores theoretically when, how and why populations grow, based on empirically observed patterns, has up until now played a minor role in population ethics. Similarly, debates about population dynamics among demographers have seldom been concerned with ideas and concepts in population ethics. In this manuscript, I will give a brief outline of how population size, population growth, and welfare mutually affect each other. Theories on the endogeneity between population size, population growth, and welfare will be referred to as demographic theory. I will give a particular focus on how population growth responds with respect to welfare, as welfare, utility, well-being, and happiness are important concepts in population ethics. A key concept in demographic theory is population homeostasis (the dynamics of a system which maintains a population at a steady population size, or growth rate), in particular resource dependent homeostasis. I will also discuss demographic theory in relation to historical and future demographic change. This working paper was later published in Oxford Handbook of Population Ethics, and is available at https://osf.io/preprints/socarxiv/at5pj/

Tracking the Catalyst Layer Depth-Dependent Electrochemical Degradation of a Bimodal Pt/C Fuel Cell Catalyst: A Combined Operando Small- and Wide-Angle X-Ray Scattering Study

The combination of operando small- and wide-angle X-ray scattering (SAXS, WAXS) is here presented to provide insights into the changes in mean particle sizes and phase fractions in fuel cell catalyst layers during accelerated stress tests (ASTs). As fuel cell catalyst, a bimodal Pt/C catalyst was chosen that consists of two distinguishable particle size populations. The presence of the two different sizes should favor and uncover electrochemical Ostwald ripening as degradation mechanism, i.e., the growth of larger particles in the Pt/C catalyst at the expense of the smaller particles via the formation of ionic metal species. However, instead of electrochemical Ostwald ripening, the results point toward classical Ostwald ripening via the local diffusion of metal atoms on the support. Furthermore, the grazing incidence mode provides insights into the catalyst layer depth-dependent degradation. While the larger particles show the same particle size changes close to the electrolyte-catalyst interface and within the catalyst layer, the smaller Pt nanoparticles exhibit a slightly decreased size at the electrolyte-catalyst interface. During the AST, both size populations increase in size, independent of the depth. Their phase fraction, i.e., the ratio of smaller to larger size population, however, exhibits a depth-dependent behavior. While at the electrolyte-catalyst interface the phase fraction of the smaller size population decreases, it increases in the inner catalyst layer. The results of a depth-dependent degradation suggest that employing a depth-dependent catalyst design can be used for future improvement of catalyst stability.

Tracking the Catalyst Layer Depth-Dependent Electrochemical Degradation of a Bimodal Pt/C Fuel Cell Catalyst: A Combined Operando Small- and Wide-Angle X-Ray Scattering Study

The combination of operando small- and wide-angle X-ray scattering (SAXS, WAXS) is here presented to provide insights into the changes in mean particle sizes and phase fractions in fuel cell catalyst layers during accelerated stress tests (ASTs). As fuel cell catalyst, a bimodal Pt/C catalyst was chosen that consists of two distinguishable particle size populations. The presence of the two different sizes should favor and uncover electrochemical Ostwald ripening as degradation mechanism, i.e., the growth of larger particles in the Pt/C catalyst at the expense of the smaller particles via the formation of ionic metal species. However, instead of electrochemical Ostwald ripening, the results point toward classical Ostwald ripening via the local diffusion of metal atoms on the support. Furthermore, the grazing incidence mode provides insights into the catalyst layer depth-dependent degradation. While the larger particles show the same particle size changes close to the electrolyte-catalyst interface and within the catalyst layer, the smaller Pt nanoparticles exhibit a slightly decreased size at the electrolyte-catalyst interface. During the AST, both size populations increase in size, independent of the depth. Their phase fraction, i.e., the ratio of smaller to larger size population, however, exhibits a depth-dependent behavior. While at the electrolyte-catalyst interface the phase fraction of the smaller size population decreases, it increases in the inner catalyst layer. The results of a depth-dependent degradation suggest that employing a depth-dependent catalyst design can be used for future improvement of catalyst stability.

The Human Vulvar Microbiome: A Systematic Review

The link between cancer and the microbiome is a fast-moving field in research. There is little knowledge on the microbiome in ((pre)malignant) conditions of the vulvar skin. This systematic review aims to provide an overview of the literature regarding the microbiome composition of the healthy vulvar skin and in (pre)malignant vulvar disease. This study was performed according to the PRISMA guidelines. A comprehensive, electronic search strategy was used to identify original research articles (updated September 2021). The inclusion criteria were articles using culture-independent methods for microbiome profiling of the vulvar region. Ten articles were included. The bacterial composition of the vulva consists of several genera including Lactobacillus, Corynebacterium, Staphylococcus and Prevotella, suggesting that the vulvar microbiome composition shows similarities with the corresponding vaginal milieu. However, the vulvar microbiome generally displayed higher diversity with commensals of cutaneous and fecal origin. This is the first systematic review that investigates the relationship between microbiome and vulvar (pre)malignant disease. There are limited data and the level of evidence is low with limitations in study size, population diversity and methodology. Nevertheless, the vulvar microbiome represents a promising field for exploring potential links for disease etiology and targets for therapy.

Modeling the control processes of the size population of microorganisms using modulated microwave

The paper describes a mathematical model of a control system for the size population of microorganisms using modulated microwave radiation of non-thermal power.The model is implemented in the dynamic environment MATLAB+Simulink, the areas of optimal values of the impact parameters are found. An algorithm for automatic tuning of the modulation frequency during the experiment has been developed.The efficiency of the algorithmis shown with the help of computer simulation.