Tungsten Fabricated by Laser Powder Bed Fusion

AbstractAdditive Manufacturing (AM) is the process that allows the production of complex geometry and lightweight components. Thanks to the high density of refractory metals, AM could be a possible solution for their application in the aerospace field and for biomedical or future nuclear fusion devices. Yet, Laser Powder Bed Fusion (LPBF) of refractory metals as Ta, Mo, and W faces some challenges due to their main properties: high melting point, heat conductivity, and susceptibility to cracks.The purpose of this study is to optimize the process parameters in order to produce high-density Tungsten parts by LPBF on an EOS M100 (maximum power of 170 W). The characterization is performed through physical properties measurements and microstructural analysis. Single Scan Tracks (SSTs) are produced on the top surfaces of Tungsten blocks to evaluate the process parameters that give regular-shape and continuous melt-pools. Both analytical and experimental optimizations of process parameters were performed. Micro-hardness measurements were done for dense bulk specimens. Finally, a description of susceptibility to cracks of additively manufactured Tungsten was performed

Dysfunctional mitochondria accumulate in a skeletal muscle knockout model of Smn1, the causal gene of spinal muscular atrophy

The approved gene therapies for spinal muscular atrophy (SMA), caused by loss of survival motor neuron 1 (SMN1), greatly ameliorate SMA natural history but are not curative. These therapies primarily target motor neurons, but SMN1 loss has detrimental effects beyond motor neurons and especially in muscle. Here we show that SMN loss in mouse skeletal muscle leads to accumulation of dysfunctional mitochondria. Expression profiling of single myofibers from a muscle specific Smn1 knockout mouse model revealed down-regulation of mitochondrial and lysosomal genes. Albeit levels of proteins that mark mitochondria for mitophagy were increased, morphologically deranged mitochondria with impaired complex I and IV activity and respiration and that produced excess reactive oxygen species accumulated in Smn1 knockout muscles, because of the lysosomal dysfunction highlighted by the transcriptional profiling. Amniotic fluid stem cells transplantation that corrects the SMN knockout mouse myopathic phenotype restored mitochondrial morphology and expression of mitochondrial genes. Thus, targeting muscle mitochondrial dysfunction in SMA may complement the current gene therapy

Epidemiology of schistosomiasis mansoni in a low endemic area

We discuss the epidemiological patterns of schistosomiasis mansoni in areas with low transmission in Brazil. We define as areas of low endemicity those where the prevalence is less than 10%, the number Schistosoma mansoni eggs per gram of feces (epg) is less than 96, and carriers are asymptomatic. Data are from the county of Pedro de Toledo in the Ribeira Valley (São Paulo State) and were collected randomly according to the aggregate pattern of S. mansoni within the hosts. We suggest the replacement of parasitological methods by more sensitive and specific serological techniques. The main risk factor for infection is type of leisure activity. Infection is more frequent in the 10-14, 15-19, and 20-24-year age brackets. Geometric mean epg is 58.5. Intensity of infections correlates well (rs = 0.745) with prevalence. The highest index of potential contamination is in the 5-20-year age bracket (57.6%). Autochthonous cases show close association with Biomphalaria tenagophila, which has a low infection rate (2%). Prevalence, incidence, and intensity of infection patterns are similar to those of moderate and high endemic areas. Social and cultural aspects must be studied in order to obtain a global epidemiological view of schistosomiasis.Discutem se padrões epidemiológicos da esquistossomos mansônica em áreas brasileiras de baixa endemicidade que possuem prevalência inferior a 10%, menos de 96 ovos por grama de fezes (epg) e onde os infectados são assintomáticos. Apresentam-se dados do município de Pedro de Toledo (Vale do Ribeira, SP) área de baixa endemicidade cujos resultados foram obtidos de amostragem aleatória devida à agregação de Schistosoma mansoni. Sugere-se substituição de métodos parasitológicos por técnicas sorológicas com maiores sensibilidade e especificidade. O principal fator de risco é o lazer. A infecção predomina nos grupos etários de 10-14, 15-19 e 20-24. A intensidade de infecção foi baixa, com 58,5 epg (média geométrica). Há boa correlação (rs = 0,745) entre intensidade de infecção e prevalência. Os mais altos índices de potencial de contaminação ocorreram nas idades de 5 a 20 anos (57,6%). Os casos autóctones mantêm íntimo contato com Biomphalaria tenagophila, com infecção inferior a 2%. Os padrões de prevalência, de incidência e de intensidade de infecção são semelhantes aos de áreas de moderada e alta endemicidade. Questões sócio-culturais merecem estudo para visão global da epidemiologia.S254S26

Inoculum origin and soil legacy can shape plant–soil feedback outcomes for tropical grassland restoration

This is the author accepted manuscript. The final version is available from Wiley / Society for Ecological Restoration International via the DOI in this record.Restoration techniques tailored to grasslands are needed to improve the effectiveness of restoration in tropical landscapes. In this study, we investigated the joint effects of plant–soil legacies and soil inocula in native and invaded Cerrado grasslands to evaluate whether different microbial origins affect plant–soil feedbacks and the likelihood of restoration. Using two grass species, we measured aboveground biomass, and several plant traits over two growth cycles. Species responded differently to inocula and legacies. The legacy of the invasive Urochloa eminii and invaded soil inocula positively affected mycorrhizal colonization. The legacy of Diectomis fastigiata, a commonly used species in Cerrado restoration, resulted in a negative self-feedback potentially limiting its effectiveness for restoration. The success of the invasive species was in part due to its broad ecological niche and its ability to cope with a broad range of soil conditions. Our research suggests soil inocula and legacies could be used to aid restoration efforts in the tropics, allowing restoration practitioners to stimulate the growth of species targeting functional traits for a given ecosystem.Natural Environment Research Council (NERC)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior-Brasi

Predicting Responses of Geo-ecological Carbonate Reef Systems to Climate Change: A Conceptual Model and Review

[Chapter Abstract] 230Coral reefs provide critical ecological and geomorphic (e.g. sediment production for reef-fronted shoreline maintenance) services, which interact in complex and dynamic ways. These services are under threat from climate change, requiring dynamic modelling approaches that predict how reef systems will respond to different future climate scenarios. Carbonate budgets, which estimate net reef calcium carbonate production, provide a comprehensive ‘snap-shot’ assessment of reef accretionary potential and reef stability. These budgets, however, were not intended to account for the full suite of processes that maintain coral reef services or to provide predictive capacity on longer timescales (decadal to centennial). To respond to the dual challenges of enhancing carbonate budget assessments and advancing their predictive capacity, we applied a novel model elicitation and review method to create a qualitative geo-ecological carbonate reef system model that links geomorphic, ecological and physical processes. Our approach conceptualizes relationships between net carbonate production, sediment transport and landform stability, and rates knowledge confidence to reveal major knowledge gaps and critical future research pathways. The model provides a blueprint for future coral reef research that aims to quantify net carbonate production and sediment dynamics, improving our capacity to predict responses of reefs and reef-fronted shorelines to future climate change.https://nsuworks.nova.edu/occ_facbooks/1116/thumbnail.jp

New insights into the genetic diversity of Schistosoma mansoni and S. haematobiumin Yemen

The file attached is the Published/publisher’s pdf version of the article.© 2015 Sady et al. Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated

Now, switch! Individuals’ responses to imposed switches between exploration and exploitation

Individual ambidexterity is an important micro-foundation of organizational ambidexterity. However, switching back-and-forth between exploration and exploitation can be challenging for individuals. Prior research has mostly focused on bottom-up approaches to stimulating individual ambidexterity, yet many organizations are characterized by greater top-down control. Exercising control may complicate the pursuit of individual ambidexterity because it amplifies switching resistance. We draw on an observational study of facilitated strategy workshops to explore the role of switching resistance and steps that can be taken to deal with it in top-down settings. Our findings suggest that imposing switches on individuals tends to trigger a distinct pattern of behavioral responses. Furthermore, we find that increasing control and offering emotional support can reduce switching resistance and help individuals execute ambidextrous work tasks. Our study contributes to the literature on individual ambidexterity by extending it from bottom-up to top-down settings. Specifically, we identify emotional, cognitive and behavioral drivers of switching resistance and unpack the process leading up to resistance. Furthermore, we identify organizational measures relevant for addressing such resistance and resolving ambidexterity at the individual level.info:eu-repo/semantics/publishedVersio