The long theorized two-dimensional allotrope of SiC has remained elusive amid the exploration of graphenelike honeycomb structured monolayers. It is anticipated to possess a large direct band gap ...(2.5 eV), ambient stability, and chemical versatility. While sp^{2} bonding between silicon and carbon is energetically favorable, only disordered nanoflakes have been reported to date. Here we demonstrate large-area, bottom-up synthesis of monocrystalline, epitaxial monolayer honeycomb SiC atop ultrathin transition metal carbide films on SiC substrates. We find the 2D phase of SiC to be almost planar and stable at high temperatures, up to 1200 °C in vacuum. Interactions between the 2D-SiC and the transition metal carbide surface result in a Dirac-like feature in the electronic band structure, which in the case of a TaC substrate is strongly spin-split. Our findings represent the first step towards routine and tailored synthesis of 2D-SiC monolayers, and this novel heteroepitaxial system may find diverse applications ranging from photovoltaics to topological superconductivity.
This study identified the occurrence of Holocene chronology hiatuses in the sedimentary record of the Patos-Mirim system caused by river avulsion processes, as well as evidence of sharp anthropogenic ...changes in the surrounding region of the lagoon water bodies. The presence of chronology hiatuses demonstrates the importance of considering the disturbance effect of paleo-drainage processes on the paleoenvironmental resolution and expression of the sedimentary record of such coastal plains. Anthropogenic activities especially those related to agriculture and forestry have increased significantly during the great acceleration, resulting in modifications of both the landscape and the environmental conditions of the lagoon bodies. Such impacts were clearly reflected in the sedimentary record where abrupt changes in palynological trends, sedimentary DNA, isotopic and granulometric analyses were inferred. The climatic conditions combined with regressive sea level can explain the chronology hiatuses. Pollen analyses demonstrated changes in the landscape, particularly indicated by the shift from Cyperaceae to Poaceae dominance after the 1960 CE. Therefore, all proxies together demonstrate the modification in the landscape and changes in the environment, clearly influenced by anthropogenic action from unsustainable agricultural practices.
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•The Patos-Mirim system is extensively dissected by Pleistocene/Holocene incised valleys.•The Holocene record is eroded by currents of meandering streams, which expression consisted of a Middle Holocene hiatus.•Novel palynological and 16S rRNA long-term data demonstrate changes in both landscape and lagoon anthropogenic transformation.
Saxitoxin is a cyanotoxin which is very harmful to human health; the concentration limit in drinking water is only 3 μg/L. Therefore, a simple, fast, sensitive, low-cost, and specific method for its ...detection, quantification, and monitoring in water bodies is needed to avoid adverse effects on animal and human health. In this work, we developed an electrochemical impedimetric biosensor using a specific aptamer as recognition element for saxitoxin detection. This method allies the superior sensing characteristics of aptamers with the nondestructive, label-free, and easy working principles of the electrochemical impedance technique. The device presented sensitivity for detecting saxitoxin concentrations above 0.3 μg/L, with high selectivity in negative control experiments, demonstrating a promising alternative for water toxin detection.
Graphical abstract
Petroleum activity is characterized as a high-risk activity due to the probability of accidents with material and human losses. The leaders of this segment assume, besides the complex routine tasks, ...the challenge of making assertive decisions during an accident. This study aims to present an evaluation model of the Industry Leadership Index for Emergencies Situations ( ILIE ), using the Adaptive Neuro-Fuzzy System (ANFIS). The model was composed of 4 input variables, namely: knowledge, behavior, skill, and attitude; and one output variable, Industry Leadership. The data collection took place in petroleum production units in Brazil, with a sample of 151 respondents through the application of a survey. The observed data were treated in an Excel tabulator and used in the development of the ANFIS model. From this model, it was possible to carry out simulations to predict the impact, which the increase or decrease in the value of each input variable can influence the leader's profile. The model performed satisfactorily in the Root of the Mean Square Error (RMSE) analysis, being 0.199 in data training and 1.217 in data verification. The results suggest that the ANFIS method can be successfully applied to establish a model to analyze industry leaders prepared for assertive responses in crisis scenarios.
We recently reported on a new class of branched amphiphilic peptides that associate with double stranded DNA and promote in vitro transfection of eukaryotic cells. In the present study, we tested a ...different formulation in which plasmid DNA associates with the surface of preformed 20–30nm cationic capsules formed through the self-assembly of the two branched amphiphilic peptides. Under these conditions, the negatively charged DNA interacts with the cationic surface of the Branched Amphiphilic Peptide Capsules (BAPCs) through numerous electrostatic interactions generating peptide-DNA complexes with sizes ranging from 50 to 250nm. The BAPCs-DNA nanoparticles are capable of delivering plasmid DNA of different size into cells in culture, yielding high transfection rates and minimal cytotoxicity. Furthermore, BAPCs were tested for in vivo delivery of a DNA vaccine previously designed to activate immune responses and capable of controlling tumors induced by type 16 human papilloma virus (HPV-16). The BAPCs-DNA nanoparticles enhanced the vaccine-induced antitumor protection and promoted activation of murine dendritic cells without significant toxic effects. These results indicate that branched amphiphilic oligo-peptides nanoparticles represent a new and promising nonviral DNA/gene delivery approach endowing immunomodulatory properties for DNA vaccines.
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Heart transplant (HT) recipients may be at higher risk of acquiring SARS-CoV-2 infection and developing critical illness. The aim of this study is to describe characteristics and outcomes of HT ...recipients infected by SARS-COV-2, from a high-volume transplant center.
We have described data of all adult HT recipients with confirmed coronavirus disease 2019 by RT-PCR in nasopharyngeal samples from April 5, 2020, to January 5, 2021. Outcomes and follow-up were recorded until February 5, 2021.
Forty patients were included. Twenty-four patients (60%) were men; the median age was 53 (40-60) y old; median HT time was 34 mo; and median follow-up time 162 d. The majority needed hospitalization (83%). Immunosuppressive therapy was reduced/withdrawn in the majority of patients, except from steroids, which were maintained. Seventeen patients (42.5%) were classified as having severe disease according to the ordinal scale developed by the World Health Organization Committee. They tended to have lower absolute lymphocyte count (P < 0.001) during follow-up when compared with patients with mild disease. Thirty-day mortality was 12.5%. However, a longer follow-up revealed increased later mortality (27.5%), with median time to death around 35 d. Bacterial nosocomial infections were a leading cause of death. Cardiac allograft rejection (10%) and ventricular dysfunction (12.5%) were also not negligible.
Major findings of this study corroborate other cohorts' results, but it also reports significant rate of later events, suggesting that a strict midterm surveillance is advisable to HT recipients with coronavirus disease 2019.
Abstract
Background
Primary graft dysfunction (PGD) is the leading cause of death in the first year after heart transplant (HT). Physiopathology of PGD is not clear, and histological findings are not ...defined in literature.
Purpose
The objective of this study is to describe the morphological findings in the hearts of patients who died within the first 14 days after HT and to compare findings between 2 groups: a group with the diagnosis of PGD and a group without PGD.
Methods
We included all adult patients submitted to HT in one center who died within the first 14 days after the procedure and were submitted to necropsy between January 1st, 2013 and March 31st, 2020. Demographic, perioperative, histological and immunohistochemical data on heart slides obtained on necropsy were recorded retrospectively. We retrospectively analyzed if the patients met the ISHLT criteria for PGD, and then we categorized them in two groups: PGD group or non-PGD group. All heart slides were reviewed by an experienced pathologist considering the presence of histological features of acute cellular rejection, antibody-mediated rejection, necrosis and its morphological characteristics if present. Pathologist was blind for each patient group. We considered the necrosis significant if it took more than 10% of the examined area. All findings were compared between groups.
Results
Among 322 HTs performed, 31 patients died within 14 days after the procedure. Five patients were not subjected to autopsy, and the remaining 26 patients were included. Twelve patients presented PGD, while 14 patients did not. Comparison between groups shows longer ischemia time, higher incidence of pre-transplant mechanical circulatory support, lower post-transplant left ventricular ejection fraction and higher incidence of post-transplant right ventricular dysfunction in PGD group (Table 1). Necropsy findings were similar between groups and four patterns of necrosis were found, namely microcalcified, contraction-band, coagulative and liquefactive necrosis (Table 2). Necrosis was detected in the 80.7% of all cases, taking more than 10% of the myocardial area in 46.1% of them. Seven patients (26.9%) presented signs of mild cellular rejection (1R). One of them had also antibody-mediated rejection. One patient presented hyperacute graft rejection. The cause of death was defined by necropsy in 21 cases. The most common cause of death in PDG group was cardiogenic shock (66.7%), while in non-PGD group septic shock (28.5%) and bleeding (21.4%) were the most common causes.
Conclusion
While left ventricular ejection fraction was significantly lower in PGD group, necrosis was a frequent finding both groups, raising the hypothesis maybe necrosis is not directly the cause of cardiac dysfunction in PGD. More studies are needed to fully understand PGD pathology.Table 1Table 2
Summary
Background
Asthma is a common chronic respiratory disease in children and adults. An important genetic component to asthma susceptibility has long been recognized, most recently through the ...identification of several genes (e.g., ORMDL3, PDE4D, HLA‐DQ, and TLE4) via genome‐wide association studies.
Objective
To identify genetic variants associated with asthma affection status using genome‐wide association data.
Methods
We describe results from a genome‐wide association study on asthma performed in 3855 subjects using a panel of 455 089 single nucleotide polymorphisms (SNPs).
Result
The genome‐wide association study resulted in the prioritization of 33 variants for immediate follow‐up in a multi‐staged replication effort. Of these, a common polymorphism (rs9272346) localizing to within 1 Kb of HLA‐DQA1 (chromosome 6p21.3) was associated with asthma in adults (P‐value = 2.2E‐08) with consistent evidence in the more heterogeneous group of adults and children (P‐value = 1.0E‐04). Moreover, some genes identified in prior asthma GWAS were nominally associated with asthma in our populations.
Conclusion
Overall, our findings further replicate the HLA‐DQ region in the pathogenesis of asthma. HLA‐DQA1 is the fourth member of the HLA family found to be associated with asthma, in addition to the previously identified HLA‐DRA, HLA‐DQB1 and HLA‐DQA2.
Laboratory tests showed total cholesterol of 785 mg/dl, low-density lipoprotein cholesterol (LDL) of 710 mg/dl, triglycerides (TG) of 221 mg/dl, and high-density lipoprotein cholesterol (HDL) of 31 ...mg/dl.
A variety of experiments on vacuum-deposited methylammonium lead iodide perovskite solar cells are presented, including JV curves with different scan rates, light intensity-dependent open-circuit ...voltage, impedance spectra, intensity-modulated photocurrent spectra, transient photocurrents, and transient voltage step responses. All these experimental data sets are successfully reproduced by a charge drift-diffusion simulation model incorporating mobile ions and charge traps using a single set of parameters. While previous modeling studies focused on a single experimental technique, we combine steady-state, transient, and frequency-domain simulations and measurements. Our study is an important step toward quantitative simulation of perovskite solar cells, leading to a deeper understanding of the physical effects in these materials. The analysis of the transient current upon voltage turn-on in the dark reveals that the charge injection properties of the interfaces are triggered by the accumulation of mobile ionic defects. We show that the current rise of voltage step experiments allow for conclusions about the recombination at the interface. Whether one or two mobile ionic species are used in the model has only a minor influence on the observed effects. A delayed current rise observed upon reversing the bias from +3 to −3 V in the dark cannot be reproduced yet by our drift-diffusion model. We speculate that a reversible chemical reaction of mobile ions with the contact material may be the cause of this effect, thus requiring a future model extension. A parameter variation is performed in order to understand the performance-limiting factors of the device under investigation.
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