Functionalized carbon nanocones performance in water harvesting.

In this work, we investigate the water capture process for functionalized carbon nanocones (CNCs) through molecular dynamic simulations in the following three scenarios: a single CNC in contact with a reservoir containing liquid water, a single CNC in contact with a water vapor reservoir, and a combination of more than one CNC in contact with vapor. We found that water flows through the nanocones when in contact with the liquid reservoir if the nanocone tip presents hydrophilic functionalization. In contact with steam, we observed the formation of droplets at the base of the nanocone only when hydrophilic functionalization is present. Then, water flows through in a linear manner, a process that is more efficient than that in the liquid reservoir regime. The scalability of the process is tested by analyzing the water flow through more than one nanocone. The results suggest that the distance between the nanocones is a fundamental ingredient for the efficiency of water harvesting.

Self-perceived competences by future chemistry teachers in Brazil.

In this work we have compared the self-perceived competences of future chemistry teachers who are pursuing teacher training courses in all the regions of Brazil taking the following factors into account: sex, age and Brazilian region origin. A quantitative exploration was adopted and the data were collected using the Self-Perceived Competences of Teachers in Initial Chemistry Training (SPCTICT) instrument, composed of 21 items. An exploratory factor analysis enabled grouping the items into three factors: (a) self-perception of technical competences (knowledge), (b) Self-perception of competences linked to specific aspects (know-how) and, finally, (c) self-perception of generic competences (knowing how to act or how to behave). The results demonstrate statistically significant differences among men and women on the self-perception of their own competences regarding knowledge construction in chemistry.

Androcentrism in the scientific field: Brazilian systems of graduate studies, science and technology as a case study.

This article performs an analysis of female participation in science, in the Brazilian system of graduate studies and scientific research as a case study. This is relevant because science is a central supporting structure for modern societies and, therefore, a detailed analysis of the scientific power structure behind academic policy creation can reveal aspects of androcentrism in scientific activity. The main goal of this work is to identify the process of misogyny in science by describing its reproductive pattern. Our results show that women are around 50% of the undergraduate and graduate students when all fields are taken into consideration, but only 37% of the researchers in the CNPq system. We also observe a significant increase in female percentage within scientific activities at the initial and intermediary levels, except for the most prestigious areas as hard science. However, a scissor effect is identified between the initial level and the more prominent positions. This unbalanced participation reveals that female occupations in science are mostly as lower workforce since women are quite far from the social decision-making circles in this career.

Structure and dynamics of nanoconfined water and aqueous solutions.

This review is devoted to discussing recent progress on the structure, thermodynamic, reactivity, and dynamics of water and aqueous systems confined within different types of nanopores, synthetic and biological. Currently, this is a branch of water science that has attracted enormous attention of researchers from different fields interested to extend the understanding of the anomalous properties of bulk water to the nanoscopic domain. From a fundamental perspective, the interactions of water and solutes with a confining surface dramatically modify the liquid's structure and, consequently, both its thermodynamical and dynamical behaviors, breaking the validity of the classical thermodynamic and phenomenological description of the transport properties of aqueous systems. Additionally, man-made nanopores and porous materials have emerged as promising solutions to challenging problems such as water purification, biosensing, nanofluidic logic and gating, and energy storage and conversion, while aquaporin, ion channels, and nuclear pore complex nanopores regulate many biological functions such as the conduction of water, the generation of action potentials, and the storage of genetic material. In this work, the more recent experimental and molecular simulations advances in this exciting and rapidly evolving field will be reported and critically discussed.

Water mobility in MoS2 nanopores: effects of the dipole-dipole interaction on the physics of fluid transport.

Use of nanoscale materials is a promising desalination technology. While fast water flow in nanotubes is well understood, this is not the case for water permeability in single-layer membranes. The advances in nanofluidics have opened up the possibility to shift the permeability-selectivity tradeoff. The physical-chemical balance between nanopore size, shape, and charge might be the answer. In this work, we investigate the role of the MoS2 nanopore charge distribution in water mobility by tuning its strength. We shed light on the competition between charge and nanopore size. The strong dipole interaction between water and the MoS2 nanopore is responsible for adding a constraint to the water angular orientation possibilities to travel through the nanopore, but this effect also depends on the nanopore size.

Molecular fluid flow in MoS2 nanoporous membranes and hydrodynamics interactions.

We study the impact of the induced pressure fields on the water flow and salt rejection in nanopores produced in MoS2 membranes. We observe that the water permeability and the salt rejection are not impacted by the distance between the pores. This result contradicts the continuous fluid mechanics calculations in microfilters, which indicates the existence of hydrodynamic interactions between adjacent pores that increase the water mobility. Our results suggest that at this nanoscale, the hydrodynamic interactions do not affect the water mobility through nanopores.

Echocardiographic screening of pregnant women by non-physicians with remote interpretation in primary care.

BACKGROUND: Impact of heart disease (HD) on pregnancy is significant. OBJECTIVE: We aimed to evaluate the feasibility of integrating screening echocardiography (echo) into the Brazilian prenatal primary care to assess HD prevalence. METHODS: Over 13 months, 20 healthcare workers acquired simplified echo protocols, utilizing hand-held machines (GE-VSCAN), in 22 primary care centres. Consecutive pregnant women unaware of HD underwent focused echo, remotely interpreted in USA and Brazil. Major HD was defined as structural valve abnormalities, more than mild valve dysfunction, ventricular systolic dysfunction/hypertrophy, or other major abnormalities. Screen-positive women were referred for standard echo. RESULTS: At total, 1 112 women underwent screening. Mean age was 27 ± 8 years, mean gestational age 22 ± 9 weeks. Major HD was found in 100 (9.0%) patients. More than mild mitral regurgitation was observed in 47 (4.2%), tricuspid regurgitation in 11 (1.0%), mild left ventricular dysfunction in 4 (0.4%), left ventricular hypertrophy in 2 (0.2%) and suspected rheumatic heart disease in 36 (3.2%): all, with mitral valve and two with aortic valve (AV) involvement. Other AV disease was observed in 11 (10%). In 56 screen-positive women undergoing standard echo, major HD was confirmed in 45 (80.4%): RHD findings in 12 patients (all with mitral valve and two with AV disease), mitral regurgitation in 40 (14 with morphological changes, 10 suggestive of rheumatic heart disease), other AV disease in two (mild/moderate regurgitation). CONCLUSIONS: Integration of echo screening into primary prenatal care is feasible in Brazil. However, the low prevalence of severe disease urges further investigations about the effectiveness of the strategy.

Impact of incorporating echocardiographic screening into a clinical prediction model to optimise utilisation of echocardiography in primary care.

INTRODUCTION: Access to public subspecialty healthcare is limited in underserved areas of Brazil, including echocardiography (echo). Long waiting lines and lack of a prioritisation system lead to diagnostic lag and may contribute to poor outcomes. We developed a prioritisation tool for use in primary care, aimed at improving resource utilisation, by predicting those at highest risk of having an abnormal echo, and thus in highest need of referral. METHODS: All patients in the existing primary care waiting list for echo were invited for participation and underwent a clinical questionnaire, simplified 7-view echo screening by non-physicians with handheld devices, and standard echo by experts. Two derivation models were developed, one including only clinical variables and a second including clinical variables and findings of major heart disease (HD) on echo screening (cut point for high/low-risk). For validation, patients were risk-classified according to the clinical score. High-risk patients and a sample of low-risk underwent standard echo. Intermediate-risk patients first had screening echo, with a standard echo if HD was suspected. Discrimination and calibration of the two models were assessed to predict HD in standard echo. RESULTS: In derivation (N = 603), clinical variables associated with HD were female gender, body mass index, Chagas disease, prior cardiac surgery, coronary disease, valve disease, hypertension and heart failure, and this model was well calibrated with C-statistic = 0.781. Performance was improved with the addition of echo screening, with C-statistic = 0.871 after cross-validation. For validation (N = 1526), 227 (14.9%) patients were classified as low risk, 1082 (70.9%) as intermediate risk and 217 (14.2%) as high risk by the clinical model. The final model with two categories had high sensitivity (99%) and negative predictive value (97%) for HD in standard echo. Model performance was good with C-statistic = 0.720. CONCLUSION: The addition of screening echo to clinical variables significantly improves the performance of a score to predict major HD.

Open Access Publications with Article Processing Charge (APC) Payment: a Brazilian Scenario Analysis.

The expansion of open access publications has been correlated with specific government policies in many countries. The evolution in these cases is understandable within the framework of funding regulations. However, this is not the case for Brazil, where no regulation is currently in place. The unusually high percentage of open access publications in the Brazilian scientific community is analyzed here toward understanding which factors influence this growth and how similar effects may also impact other countries, particularly developing nations. We found that from 2012 to 2019 the Brazilian scientific community drifted to international open access journals. This transition is discussed in the framework of mega journals.

Misogyny in Brazilian Federal Government Agencies for Science and High-Education.

The transformation of women's role in society has been systematically studied. Numerous authors point out that among the factors of extreme relevance to this fact, the main is the increased presence of women in the formal job market. Researches also reveal that the increase in quantity is not reflected equally in all productive sectors nor the egalitarian occupation of high hierarchical positions. The present study aimed to analyze how the presence of women, especially in leadership positions, has evolved at the Brazilian Federal Agency for the Support and Evaluation of Postgraduate Education (CAPES) and the National Council for Scientific and Technological Development (CNPq) over the last 20 years. For these analyzes, surveys were conducted in the people management systems of the Brazilian Federal Public Administration. The initial hypothesis was that female attendance had increased in both the total number of female servants and in management and auxiliary positions, known as DAS in Brazil; however, evidence shows that women reduced overall agency presence, especially in the number of female Analysts occupying DAS positions. These results indicate that the misogyny observed in the academic sphere of the Brazilian National Postgraduate and Science, Technology, and Innovation systems are replicated in the politic-bureaucratic sphere that manages and sponsors these systems.

Correction: Salt parameterization can drastically affect the results from classical atomistic simulations of water desalination by MoS2 nanopores.

Correction for 'Salt parameterization can drastically affect the results from classical atomistic simulations of water desalination by MoS2 nanopores' by João P. K. Abal et al., Phys. Chem. Chem. Phys., 2020, 22, 11053-11061, DOI: 10.1039/d0cp00484g.

Salt parameterization can drastically affect the results from classical atomistic simulations of water desalination by MoS2 nanopores.

Water scarcity is a reality in our world, and scenarios predicted by leading scientists in this area indicate that it will worsen in the next decades. However, new technologies based on low-cost seawater desalination can prevent the worst scenarios, providing fresh water for humanity. With this goal, membranes based on nanoporous materials have been suggested in recent years. One of the materials suggested is MoS2, and classical Molecular Dynamics (MD) simulation is one of the most powerful tools to explore these nanomaterials. However, distinct force fields employed in MD simulations are parameterized based on distinct experimental quantities. In this paper, we compare two models of salt that were built based on distinct properties of water-salt mixtures. One model fits the hydration free energy and lattice properties, and the second fits the crystal density and the density and the dielectric constant of water and salt mixtures. To compare the models, MD simulations for salty water flow through nanopores of two sizes were used - one pore big enough to accommodate hydrated ions, and one smaller in which the ion has to dehydrate to enter - and two rigid water models from the TIP4P family - TIP4P/2005 and TIP4P/ε. Our results indicate that the water permeability and salt rejection by the membrane are more influenced by the salt model than by the water model, especially for the narrow pore. In fact, completely distinct mechanisms were observed, and they are related to the characteristics employed in the ion model parameterization. The results show that not only can the water model influence the outcomes, but the ion model plays a crucial role when the pore is small enough.

Water diffusion in carbon nanotubes: Interplay between confinement, surface deformation, and temperature.

In this article, we investigate, through molecular dynamics simulations, the diffusion behavior of the TIP4P/2005 water confined in pristine and deformed carbon nanotubes (armchair and zigzag). To analyze different diffusive mechanisms, the water temperature was varied as 210 ≤ T ≤ 380 K. The results of our simulations reveal that water presents a non-Arrhenius to Arrhenius diffusion crossover. The confinement shifts the diffusion transition to higher temperatures when compared with the bulk system. In addition, for narrower nanotubes, water diffuses in a single line, which leads to its mobility independent of the activation energy.

Water diffusion in rough carbon nanotubes.

We use molecular dynamics simulations to study the diffusion of water inside deformed carbon nanotubes with different degrees of deformation at 300 K. We found that the number of hydrogen bonds that water forms depends on nanotube topology, leading to enhancement or suppression of water diffusion. The simulation results reveal that more realistic nanotubes should be considered to understand the confined water diffusion behavior, at least for the narrowest nanotubes, when the interaction between water molecules and carbon atoms is relevant.

Association of Xpert MTB/RIF Cycle Threshold Values with Tuberculosis Treatment Outcomes.

PURPOSE: Considering the current recommendation of the World Health Organization to replace sputum smear microscopy with Xpert MTB/RIF as an initial diagnostic test for tuberculosis (TB), and that culture takes time to provide results, the cycle threshold (CT) of the Xpert test may be the only way to assess bacillary load. The objective of this study is to evaluate the association of bacillary load, measured by the Xpert CT, with the TB treatment outcomes. METHODS: In cohort study, Xpert CT values were evaluated in cured and non-cured (failure and death) patients. Multivariate analysis was performed to evaluate if CT is independently associated with TB treatment outcomes. RESULTS: During this study period, 155 patients (84 cured and 71 non-cured) met the inclusion and were included in the analysis. The mean CT value for Xpert MTB/RIF test was 20.7 ± 5.6 in cured patients and 17.1 ± 5.6 in non-cured patients (p < 0.0001). Previous TB was more frequent in non-cured (28.2%) than in cured patients (7.1%) (p < 0.0001). Non-cured patients were younger than cured ones (37.1 ± 13.3 vs 43.6 ± 16.2; p = 0.006). HIV was more frequent in non-cured (28.2%) than in cured patients (15.5%), although this difference was not statistically significant (p = 0.054). In multivariate analysis, CT values, age, previous TB, and HIV were independently associated with non-cure. CONCLUSIONS: Lower Xpert MTB/RIF CT values were independently associated with worse treatment outcomes. The information from even a single test performed before starting treatment proved to be a relatively good predictor of TB treatment outcome.

2D nanoporous membrane for cation removal from water: Effects of ionic valence, membrane hydrophobicity, and pore size.

Using molecular dynamic simulations, we show that single-layers of molybdenum disulfide (MoS2) and graphene can effectively reject ions and allow high water permeability. Solutions of water and three cations with different valencies (Na+, Zn2+, and Fe3+) were investigated in the presence of the two types of membranes, and the results indicate a high dependence of the ion rejection on the cation charge. The associative characteristic of ferric chloride leads to a high rate of ion rejection by both nanopores, while the monovalent sodium chloride induces lower rejection rates. Particularly, MoS2 shows 100% of Fe3+ rejection for all pore sizes and applied pressures. On the other hand, the water permeation does not vary with the cation valence, having dependence only with the nanopore geometric and chemical characteristics. This study helps us to understand the fluid transport through a nanoporous membrane, essential for the development of new technologies for the removal of pollutants from water.

Association of Radiological Findings with the Xpert MTB/RIF Test in Patients with Suspected Pulmonary Tuberculosis.

PURPOSE: Tuberculosis (TB) treatment is often carried out empirically, based on clinical and radiological findings. Chest X-ray (CXR) has good sensitivity but poor specificity in TB diagnosis. Xpert MTB/RIF (Mycobacterium tuberculosis/Rifampicin) is increasingly used in many countries as the initial diagnostic test for TB. The aim of the present study was to evaluate the association of radiological findings with the Xpert MTB/RIF test in patients with suspected pulmonary TB. METHODS: Cross-sectional study in an outpatient TB clinic. Sputum AFB smear, culture, Xpert MTB/RIF, and CXR were collected in patients with suspected pulmonary TB. RESULTS: During the study period, 312 patients met the inclusion criteria and were included in the analysis. Among Xpert MTB/RIF-positive cases, the radiographic patterns were classified as typical of TB, compatible of TB, and normal in 78 (70.3%), 31 (27.9%), and 2 (1.8%) patients, respectively. CXRs were classified as typical of TB, compatible of TB, and normal in 20 (10.0%), 25 (12.4%), and 152 (75.6%) patients, respectively, in Xpert MTB/RIF-negative cases. CONCLUSIONS: We found an association between radiographic patterns and Xpert MTB/RIF results in patients with suspected pulmonary TB. These results confirm the current recommended diagnosis algorithm.

Geographic and Gender Diversity in the Brazilian Academy of Sciences.

Recent studies have shown that diversity in race and gender is important to improve competitiveness, creativity and innovation. However, many studies have shown that the universe of science is not diverse in none of these criteria. In this work, we quantify the gender and geographic diversity in the Brazilian science. We study in detail the profile of the titular members of the most prestigious academic institution of Brazil, the Brazilian Academy of Sciences (ABC). Our analysis shows that the members of the ABC concentrates 80% in the Southeast region and that the overwhelming majority is composed by men. We show that female and male researchers have roughly the same amount of publication per year but women produce more human resources. Using the Brazilian Researchers' Fellowship databank we show that the gender and diversity both in gender and in geography decreases along the researchers' career.

Breakdown of the Stokes-Einstein water transport through narrow hydrophobic nanotubes.

In this paper the transport properties of water confined inside hydrophobic and hydrophilic nanotubes are compared for different nanotube radii and densities. While for wider nanotubes the nature of the wall plays no relevant role in the water mobility, for small nanotubes the hydrophobic confinement presents a peculiar behavior. As the density is increased the viscosity shows a huge increase associated with a small increase in the diffusion coefficient. This breakdown in the Stokes-Einstein relation for diffusion and viscosity was observed in the hydrophobic, but not in the hydrophilic nanotubes. The mechanism underlying this behavior is explained in terms of the structure of water under confinement. This result indicates that some of the features observed for water inside hydrophobic carbon nanotubes cannot be observed in other nanopores.

Structure and mobility of water confined in AlPO4-54 nanotubes.

We performed molecular dynamics simulations of water confined within AlPO4-54 nanotubes. AlPO4-54 is an artificial material made of AlO4 and of PO4 in tetrahedra arranged in a periodic structure forming pores of approximately 1.3 nm in diameter. This makes AlPO4-54 an excellent candidate for practical applications, such as for water filtration and desalination. In this work, the structural and dynamical properties of the confined water are analyzed for various temperatures and water loadings. We find that the water structure is controlled by the heterogeneity of the nanopore surface with the water molecules located preferentially next to the surface of oxygens of AlPO4-54; consequently, at very low densities, water forms helicoidal structures in string-like arrangements.