Microgravity studies of solidification patterns in model transparent alloys onboard the International Space Station.

We review recent in situ solidification experiments using nonfaceted model transparent alloys in science-in-microgravity facilities onboard the International Space Station (ISS), namely the Transparent Alloys (TA) apparatus and the Directional Solidification Insert of the DEvice for the study of Critical Liquids and Crystallization (DECLIC-DSI). These directional-solidification devices use innovative optical videomicroscopy imaging techniques to observe the spatiotemporal dynamics of solidification patterns in real time in large samples. In contrast to laboratory conditions on ground, microgravity guarantees the absence or a reduction of convective motion in the liquid, thus ensuring a purely diffusion-controlled growth of the crystalline solid(s). This makes it possible to perform a direct theoretical analysis of the formation process of solidification microstructures with comparisons to quantitative numerical simulations. Important questions that concern multiphase growth patterns in eutectic and peritectic alloys on the one hand and single-phased, cellular and dendritic structures on the other hand have been addressed, and unprecedented results have been obtained. Complex self-organizing phenomena during steady-state and transient coupled growth in eutectics and peritectics, interfacial-anisotropy effects in cellular arrays, and promising insights into the columnar-to-equiaxed transition are highlighted.

Solidification furnace for in situ observation of bulk transparent systems and image analysis methods.

This paper aims to describe the experimental framework of the Directional Solidification Insert, installed onboard the International Space Station, dedicated to the in situ and real-time characterization of the dynamic selection of the solid-liquid interface morphology in bulk samples of transparent materials under diffusive growth conditions. The in situ observation of the solid-liquid interface is an invaluable tool for gaining knowledge on the time evolution of the interface pattern because the initial morphological instability evolves nonlinearly and undergoes a reorganization process. The result of each experiment, characterized by the sample concentration, a thermal gradient, and a pulling rate, is a large number of images. The interpretation of these images necessitates a robust identification of each cell/dendrite's position and size during the entire solidification. Several image analysis methods have been developed to reliably achieve this goal despite varying contrast and noise levels and are described in detail. Typical solidification experiments are presented, and the dynamics of the pattern formation are analyzed to illustrate the application of the image analysis methods.

Experimental characterization and theoretical analysis of cell tip oscillations in directional solidification.

Experiments performed in DECLIC-DSI on board the International Space Station evidenced oscillatory modes during the directional solidification of a bulk sample of succinonitrile-based transparent alloy. The interferometric data acquired during a reference experiment, V_{p}=1 µm/s and G=19 K/cm, allowed us to reconstruct the cell shape and thus measure the cell tip position, radius, and growth velocity evolution, in order to quantify the dynamics of the oscillating cells. This study completes our previous reports [Bergeon et al., Phys. Rev. Lett. 110, 226102 (2013)10.1103/PhysRevLett.110.226102; Tourret et al., Phys. Rev. E 92, 042401 (2015)10.1103/PhysRevE.92.042401; Pereda et al., Phys. Rev. E 95, 012803 (2017)10.1103/PhysRevE.95.012803] with, to our knowledge, the first complete monitoring of the geometric cell tip characteristics variations in bulk samples. The evolution of the shape, velocity, and position of the tip of the oscillating cells is associated with an evolution of the concentration field, inaccessible experimentally but mediating the diffusive interactions between the cells. The experimental results are supported by 3D phase-field simulations which evidence the existence of transversal solute fluxes between neighboring cells that play a fundamental role in the oscillation dynamics. The dynamics of oscillation of an individual cell is analyzed using a theoretical model based on classical equations of solidification through the calculation of the phase relationships between oscillation of the different tip characteristics.

Neoadjuvant therapy or upfront surgery? A systematic review and meta-analysis of T2N0 esophageal cancer treatment options.

BACKGROUND: Esophageal carcinoma usually shows poor long-term survival rates, even when esophagectomy, the standard curative treatment is performed. As a result, there has been increasing interest in the neoadjuvant therapy, which could potentially downstage cancer, eliminate micrometastasis and ergo increase resectability and curative (R0) resection. Currently, for the earliest stage esophageal cancers, most guidelines point out to the role of endoscopic treatment, and for T1bN0 upfront surgery. For locally advanced cases, several studies have demonstrated the benefits of neoadjuvant therapy to increase resectability. For clinical stage T2N0 esophageal cancer, there is no consensus as to the optimal treatment strategy. METHODS: A systematic review and meta-analysis was performed to compare neoadjuvant therapy with surgery alone on clinical stage T2N0 esophageal cancer patients, concerning overall survival, recurrence, post-operative mortality, anastomotic leak, and R0 resection rate. RESULTS: For overall survival at the mean follow-up point, the neoadjuvant therapy was not associated to a higher probability of survival than upfront surgery in cT2N0 patients (risk difference: 0.00; 95% CI: -0.09, 0.09). There was no difference between neoadjuvant therapy and primary surgery concerning recurrence (risk difference: 0.21; 95% CI: -0.03, 0.45); perioperative mortality (risk difference: 0.00; 95% CI: -0.02, 0.01); and risk for anastomotic leak (risk difference: -0.08; 95% CI: -0.21, 0.05). Pooled data showed that neoadjuvant therapy was associated to a higher risk for positive margins after resection (risk difference: 0.04; 95% CI: 0.02, 0.06). CONCLUSIONS: This review showed that neoadjuvant therapy is not associated to better results than surgery alone, for the management of clinical stage T2N0 esophageal cancer patients, concerning overall survival, recurrence rate, perioperative mortality, anastomotic leak, and seems to be associated to a higher risk for resection with positive margins.

Airborne fungi in an intensive care unit / Fungos anemófilos em uma unidade de terapia intensiva

Abstract The presence of airborne fungi in Intensive Care Unit (ICUs) is associated with increased nosocomial infections. The aim of this study was the isolation and identification of airborne fungi presented in an ICU from the University Hospital of Pelotas - RS, with the attempt to know the place's environmental microbiota. 40 Petri plates with Sabouraud Dextrose Agar were exposed to an environment of an ICU, where samples were collected in strategic places during morning and afternoon periods for ten days. Seven fungi genera were identified: Penicillium spp. (15.18%), genus with the higher frequency, followed by Aspergillus spp., Cladosporium spp., Fusarium spp., Paecelomyces spp., Curvularia spp., Alternaria spp., Zygomycetes and sterile mycelium. The most predominant fungi genus were Aspergillus spp. (13.92%) in the morning and Cladosporium spp. (13.92%) in the afternoon. Due to their involvement in different diseases, the identified fungi genera can be classified as potential pathogens of inpatients. These results reinforce the need of monitoring the environmental microorganisms with high frequency and efficiently in health institutions.

Resumo A presença de fungos anemófilos nas UTIs está associada com o aumento de infecções nosocomiais. O objetivo deste estudo foi isolar e identificar quais os principais fungos anemófilos presentes em uma Unidade de Terapia Intensiva (UTI) de um Hospital Universitário de Pelotas - RS, na tentativa de conhecer a microbiota ambiental do local. Através de 40 placas de Petri com Agar Sabouraud dextrose expostas no ambiente de UTI foram coletadas amostras por exposição em locais estratégicos durante períodos da manhã e tarde por dez dias. Sete gêneros fúngicos foram identificados: Penicillium spp. (15,18%), o gênero de maior frequência, seguido de Aspergillus spp., Cladosporium spp., Fusarium spp., Paecelomyces spp., Curvularia spp., Alternaria spp., além de Zigomicetos e micélios estéreis. Houve predomínio de Aspergillus spp. (13,92%) pela manhã e Cladosporium spp. (13,92%) a tarde. Por estarem envolvidos em diferentes enfermidades, os gêneros identificados podem ser classificados como patógenos em potencial aos pacientes internados. Estes resultados reforçam a necessidade de um monitoramento dos micro-organismos ambientais com maior freqüência e eficiência nas instituições de saúde.

Airborne fungi in an intensive care unit.

The presence of airborne fungi in Intensive Care Unit (ICUs) is associated with increased nosocomial infections. The aim of this study was the isolation and identification of airborne fungi presented in an ICU from the University Hospital of Pelotas - RS, with the attempt to know the place's environmental microbiota. 40 Petri plates with Sabouraud Dextrose Agar were exposed to an environment of an ICU, where samples were collected in strategic places during morning and afternoon periods for ten days. Seven fungi genera were identified: Penicillium spp. (15.18%), genus with the higher frequency, followed by Aspergillus spp., Cladosporium spp., Fusarium spp., Paecelomyces spp., Curvularia spp., Alternaria spp., Zygomycetes and sterile mycelium. The most predominant fungi genus were Aspergillus spp. (13.92%) in the morning and Cladosporium spp. (13.92%) in the afternoon. Due to their involvement in different diseases, the identified fungi genera can be classified as potential pathogens of inpatients. These results reinforce the need of monitoring the environmental microorganisms with high frequency and efficiently in health institutions.

Experimental observation of oscillatory cellular patterns in three-dimensional directional solidification.

We present a detailed analysis of oscillatory modes during three-dimensional cellular growth in a diffusive transport regime. We ground our analysis primarily on in situ observations of directional solidification experiments of a transparent succinonitrile 0.24wt% camphor alloy performed in microgravity conditions onboard the International Space Station. This study completes our previous reports [Bergeon et al., Phys. Rev. Lett. 110, 226102 (2013)10.1103/PhysRevLett.110.226102; Tourret et al., Phys. Rev. E 92, 042401 (2015)10.1103/PhysRevE.92.042401] from an experimental perspective, and results are supported by additional phase-field simulations. We analyze the influence of growth parameters, crystal orientation, and sample history on promoting oscillations, and on their spatiotemporal characteristics. Cellular patterns display a remarkably uniform oscillation period throughout the entire array, despite a high array disorder and a wide distribution of primary spacing. Oscillation inhibition may be associated to crystalline disorientation, which stems from polygonization and is manifested as pattern drifting. We determine a drifting velocity threshold above which oscillations are inhibited, thereby demonstrating that inhibition is due to cell drifting and not directly to disorientation, and also explaining the suppression of oscillations when the pulling velocity history favors drifting. Furthermore, we show that the array disorder prevents long-range coherence of oscillations, but not short-range coherence in localized ordered regions. For regions of a few cells exhibiting hexagonal (square) ordering, three (two) subarrays oscillate with a phase shift of approximately ±120^{∘} (180^{∘}), with square ordering occurring preferentially near subgrain boundaries.

Airborne fungi in an intensive care unit

Abstract The presence of airborne fungi in Intensive Care Unit (ICUs) is associated with increased nosocomial infections. The aim of this study was the isolation and identification of airborne fungi presented in an ICU from the University Hospital of Pelotas RS, with the attempt to know the places environmental microbiota. 40 Petri plates with Sabouraud Dextrose Agar were exposed to an environment of an ICU, where samples were collected in strategic places during morning and afternoon periods for ten days. Seven fungi genera were identified: Penicillium spp. (15.18%), genus with the higher frequency, followed by Aspergillus spp., Cladosporium spp., Fusarium spp., Paecelomyces spp., Curvularia spp., Alternaria spp., Zygomycetes and sterile mycelium. The most predominant fungi genus were Aspergillus spp. (13.92%) in the morning and Cladosporium spp. (13.92%) in the afternoon. Due to their involvement in different diseases, the identified fungi genera can be classified as potential pathogens of inpatients. These results reinforce the need of monitoring the environmental microorganisms with high frequency and efficiently in health institutions.

Resumo A presença de fungos anemófilos nas UTIs está associada com o aumento de infecções nosocomiais. O objetivo deste estudo foi isolar e identificar quais os principais fungos anemófilos presentes em uma Unidade de Terapia Intensiva (UTI) de um Hospital Universitário de Pelotas RS, na tentativa de conhecer a microbiota ambiental do local. Através de 40 placas de Petri com Agar Sabouraud dextrose expostas no ambiente de UTI foram coletadas amostras por exposição em locais estratégicos durante períodos da manhã e tarde por dez dias. Sete gêneros fúngicos foram identificados: Penicillium spp. (15,18%), o gênero de maior frequência, seguido de Aspergillus spp., Cladosporium spp., Fusarium spp., Paecelomyces spp., Curvularia spp., Alternaria spp., além de Zigomicetos e micélios estéreis. Houve predomínio de Aspergillus spp. (13,92%) pela manhã e Cladosporium spp. (13,92%) a tarde. Por estarem envolvidos em diferentes enfermidades, os gêneros identificados podem ser classificados como patógenos em potencial aos pacientes internados. Estes resultados reforçam a necessidade de um monitoramento dos micro-organismos ambientais com maior freqüência e eficiência nas instituições de saúde.

Importance of educational sessions on cardiometabolic comorbidities. Awareness among psoriasis patients / Importancia de las sesiones educativas sobre comorbilidades cardiometabólicas. Conciencia entre los pacientes con psoriasis

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Van der Waals stacks of few-layer h-AlN with graphene: an ab initio study of structural, interaction and electronic properties.

Graphite-like hexagonal AlN (h-AlN) multilayers have been experimentally manifested and theoretically modeled. The development of any functional electronics applications of h-AlN would most certainly require its integration with other layered materials, particularly graphene. Here, by employing vdW-corrected density functional theory calculations, we investigate structure, interaction energy, and electronic properties of van der Waals stacking sequences of few-layer h-AlN with graphene. We find that the presence of a template such as graphene induces enough interlayer charge separation in h-AlN, favoring a graphite-like stacking formation. We also find that the interface dipole, calculated per unit cell of the stacks, tends to increase with the number of stacked layers of h-AlN and graphene.

Tuning band inversion symmetry of buckled III-Bi sheets by halogenation.

First-principles calculations are employed to investigate structural, electronic and topological insulating properties of XBi (X = B, Al, Ga, and In) monolayers upon halogenation. It is known that Y-XBi (X = Ga, In, Tl; Y = F, Cl, Br, I) can originate inversion-asymmetric topological insulators with large bulk band gaps. Our results suggest that Y-XBi (X = B, Al; Y = F, Cl, Br, I) may also result in nontrivial topological insulating phases. Despite the lower atomic number of B and Al, the spin-orbit coupling opens a band gap of about 400 meV in Y-XBi (X = B, Al), exhibiting an unusual electronic behavior for practical applications in spintronics. The nature of the bulk band gap and Dirac-cone edge states in their nanoribbons depends on the group-III elements and Y chemical species. They lead to a chemical tunability, giving rise to distinct band inversion symmetries and exhibiting Rashba-type spin splitting in the valence band of these systems. These findings indicate that a large family of Y-XBi sheets can exhibit nontrivial topological characteristics, by a proper tuning, and open a new possibility for viable applications at room temperature.