Electric Conductivity Study of Porous Polyvinyl Alcohol/Graphene/Clay Aerogels: Effect of Compression

In this work, poly(vinyl alcohol) (PVOH)/graphene (GN) oxide/clay aerogels were prepared using montmorillonite (MMT) and kaolinite (KLT) as fillers. This work paves the way for the development of aerogels filled with MMT or KLT with high conductivity. The mechanical properties of the polymer/clay aerogels are enhanced by incorporating GN into these systems. These composite materials have an enhanced thermal stability, and the combination of PVOH and GN leads to interconnected channels which favored the conductivity when a clay (MMT or KLT) is added to the mixed PVOH/GN matrix. However, after compressing the samples, the conductivities drastically decreased. These results show that the design of solid MMT/GN and KLT/GN composites as aerogels allows maximizing the space utilization of the electrode volume to achieve unhindered ion transport, which seems contrary to the general design principle of electrode materials where a suitable porous structure is desired, such as in our uncompressed samples. These findings also demonstrate the potential of these materials in electrodes, sensors, batteries, pressure-sensing applications, and supercapacitors.Financial support for this research from Ministerio de Economía y Competitividad (project AGL2015-63855-C2-2-R) (MINECO/FEDER) is gratefully acknowledged.The authors acknowledge the Servei Central d’Instrumentació Científica (SCIC-UJI) and Servei Central de Suport a la Investigació Experimental (SCSIE-UV) from Universitat Jaume I and Universitat de València, respectively, for the use of instruments and staff assistance. Authors would like to acknowledge José Ortega and Raquel Oliver for experimental support

Comparison of seven prognostic tools to identify low-risk pulmonary embolism in patients aged <50 years

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Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Une approche moléculaire de la réponse de friction ultime des fluides confinés

In order to control energy losses in mechanical systems, a thin film of lubricant is often introduced between the solids in contact. The lubricated point contacts operate in the elastohydrodynamic regime, characterized by high pressures (of the order of GPa) and thin film thicknesses (of the order of 100 nanometers). At high shear rates, the fluid may exhibit a limiting shear stress whose physical origin is still uncertain. At present, the empirical models available for the prediction of friction fail to describe the ultimate response of lubricants at these severe operating conditions. In addition, in-situ experimental analysis is very difficult to achieve due to confinement and high pressures. Thus, in this thesis, the problem is approached from the angle of modeling at the atomic scale. The shear behavior of three fluids (a traction fluid, a model lubricant and an industrial lubricant for the aerospace industry) is analyzed by Molecular Dynamics Simulation. The numerical results are then compared qualitatively and quantitatively with experimental tests. The friction response is independent of the velocity profile in the confinement thickness, the latter appearing rather as a consequence of boundary conditions at the surfaces. The limiting friction regime naturally occurs when the lubricant is subjected to thermodynamic conditions characteristic of a solid state. In this case, the dynamics of the molecules is strongly slowed down. The activation energy increases rapidly with the pressure, so that the diffusion becomes negligible at high pressure, even at the severe shear rates imposed in the Molecular Dynamics simulations. The macroscopic response to this phenomenon is thus a saturation of the value of friction. This work ends by laying the foundations of a modeling that will allow the prediction of lubricated friction under severe conditions.Afin de contrôler les pertes d'énergie dans les systèmes mécaniques, un film mince de lubrifiant est souvent introduit entre les solides en contact. Les contacts lubrifiés ponctuels fonctionnent en régime élastohydrodynamique, caractérisé par des pressions élevées (de l’ordre du GPa) et des épaisseurs de film minces (de l’ordre de 100 nanomètres). A des taux de cisaillement élevés, le fluide peut présenter une contrainte de cisaillement limite dont l’origine physique est encore incertaine. Actuellement, les modèles empiriques disponibles pour la prédiction du frottement ne décrivent pas la réponse ultime des lubrifiants dans ces conditions sévères. De plus, l'analyse expérimentale in-situ est très difficile à réaliser en raison du confinement et des fortes pressions. Ainsi, dans cette thèse, le problème est abordé sous l’angle de la modélisation à l’échelle atomique. Le comportement en cisaillement de trois de fluides (un fluide de traction, un lubrifiant modèle et un lubrifiant industriel pour le secteur aérospatial) est analysé par simulation Dynamique Moléculaire. Les résultats numériques sont ensuite comparés qualitativement et quantitativement à des essais expérimentaux. La réponse en frottement est indépendante du profile de vitesse dans l’épaisseur du confinement, ce dernier apparaissant plutôt comme une conséquence des conditions limites aux surfaces. Le régime de frottement limite apparaît naturellement lorsque le lubrifiant est soumis à des conditions thermodynamiques caractéristiques d’un état solide. Dans ce cas, la dynamique des molécules est fortement ralentie. L’énergie d’activation augmente rapidement avec la pression, de sorte que la diffusion devient négligeable à forte pression, même aux taux de cisaillement sévères imposés dans les simulations Dynamique Moléculaire. La réponse macroscopique à ce phénomène est donc une saturation de la valeur du frottement. Ce travail s’achève en jetant les bases d’une modélisation qui pourra permettre la prédiction du frottement lubrifié sous conditions sévères

Laparoscopic ureteral antero-position in a retrocaval ureter: a case report and review

Retrocaval ureter is a rare congenital anomaly due to altered development of the vasculature, in which the ureter passes behind the inferior vena cava. This is often secondary vascular variants. Here we present a case about a 41-year-old woman with pain in the right renal fossa, stenotic retrocaval ringlet was established by CT scan. RG showed 43.3 ml/min with obstructive pattern and a bordering left renal exclusion. A laparoscopic transperitoneal approach was realized. Right pyeloureteromy and anteroposition was done. The patient evolved satisfactorily, showed no signs of inflammatory systemic response and continued under post-surgical surveillance until drainage was removed, with progressively diminished serohematic output. Laparoscopic ureteral antero-position with pyeloureterotomy is considered the treatment of choice because it’s a less invasive procedure. We recommend the laparoscopic approach because of a low postsurgical complications risk

Weaning from mechanical ventilation in intensive care units across 50 countries (WEAN SAFE): a multicentre, prospective, observational cohort study

Background: Current management practices and outcomes in weaning from invasive mechanical ventilation are poorly understood. We aimed to describe the epidemiology, management, timings, risk for failure, and outcomes of weaning in patients requiring at least 2 days of invasive mechanical ventilation. Methods: WEAN SAFE was an international, multicentre, prospective, observational cohort study done in 481 intensive care units in 50 countries. Eligible participants were older than 16 years, admitted to a participating intensive care unit, and receiving mechanical ventilation for 2 calendar days or longer. We defined weaning initiation as the first attempt to separate a patient from the ventilator, successful weaning as no reintubation or death within 7 days of extubation, and weaning eligibility criteria based on positive end-expiratory pressure, fractional concentration of oxygen in inspired air, and vasopressors. The primary outcome was the proportion of patients successfully weaned at 90 days. Key secondary outcomes included weaning duration, timing of weaning events, factors associated with weaning delay and weaning failure, and hospital outcomes. This study is registered with ClinicalTrials.gov, NCT03255109. Findings: Between Oct 4, 2017, and June 25, 2018, 10 232 patients were screened for eligibility, of whom 5869 were enrolled. 4523 (77·1%) patients underwent at least one separation attempt and 3817 (65·0%) patients were successfully weaned from ventilation at day 90. 237 (4·0%) patients were transferred before any separation attempt, 153 (2·6%) were transferred after at least one separation attempt and not successfully weaned, and 1662 (28·3%) died while invasively ventilated. The median time from fulfilling weaning eligibility criteria to first separation attempt was 1 day (IQR 0-4), and 1013 (22·4%) patients had a delay in initiating first separation of 5 or more days. Of the 4523 (77·1%) patients with separation attempts, 2927 (64·7%) had a short wean (≤1 day), 457 (10·1%) had intermediate weaning (2-6 days), 433 (9·6%) required prolonged weaning (≥7 days), and 706 (15·6%) had weaning failure. Higher sedation scores were independently associated with delayed initiation of weaning. Delayed initiation of weaning and higher sedation scores were independently associated with weaning failure. 1742 (31·8%) of 5479 patients died in the intensive care unit and 2095 (38·3%) of 5465 patients died in hospital. Interpretation: In critically ill patients receiving at least 2 days of invasive mechanical ventilation, only 65% were weaned at 90 days. A better understanding of factors that delay the weaning process, such as delays in weaning initiation or excessive sedation levels, might improve weaning success rates. Funding: European Society of Intensive Care Medicine, European Respiratory Society

Weaning from mechanical ventilation in intensive care units across 50 countries (WEAN SAFE): a multicentre, prospective, observational cohort study

Background Current management practices and outcomes in weaning from invasive mechanical ventilation are poorly understood. We aimed to describe the epidemiology, management, timings, risk for failure, and outcomes of weaning in patients requiring at least 2 days of invasive mechanical ventilation. Methods WEAN SAFE was an international, multicentre, prospective, observational cohort study done in 481 intensive care units in 50 countries. Eligible participants were older than 16 years, admitted to a participating intensive care unit, and receiving mechanical ventilation for 2 calendar days or longer. We defined weaning initiation as the first attempt to separate a patient from the ventilator, successful weaning as no reintubation or death within 7 days of extubation, and weaning eligibility criteria based on positive end-expiratory pressure, fractional concentration of oxygen in inspired air, and vasopressors. The primary outcome was the proportion of patients successfully weaned at 90 days. Key secondary outcomes included weaning duration, timing of weaning events, factors associated with weaning delay and weaning failure, and hospital outcomes. This study is registered with ClinicalTrials.gov, NCT03255109. Findings Between Oct 4, 2017, and June 25, 2018, 10 232 patients were screened for eligibility, of whom 5869 were enrolled. 4523 (77·1%) patients underwent at least one separation attempt and 3817 (65·0%) patients were successfully weaned from ventilation at day 90. 237 (4·0%) patients were transferred before any separation attempt, 153 (2·6%) were transferred after at least one separation attempt and not successfully weaned, and 1662 (28·3%) died while invasively ventilated. The median time from fulfilling weaning eligibility criteria to first separation attempt was 1 day (IQR 0–4), and 1013 (22·4%) patients had a delay in initiating first separation of 5 or more days. Of the 4523 (77·1%) patients with separation attempts, 2927 (64·7%) had a short wean (≤1 day), 457 (10·1%) had intermediate weaning (2–6 days), 433 (9·6%) required prolonged weaning (≥7 days), and 706 (15·6%) had weaning failure. Higher sedation scores were independently associated with delayed initiation of weaning. Delayed initiation of weaning and higher sedation scores were independently associated with weaning failure. 1742 (31·8%) of 5479 patients died in the intensive care unit and 2095 (38·3%) of 5465 patients died in hospital. Interpretation In critically ill patients receiving at least 2 days of invasive mechanical ventilation, only 65% were weaned at 90 days. A better understanding of factors that delay the weaning process, such as delays in weaning initiation or excessive sedation levels, might improve weaning success rates