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"Ferrari, M."
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Polymer ultrapermeability from the inefficient packing of 2D chains
The promise of ultrapermeable polymers, such as poly(trimethylsilylpropyne) (PTMSP), for reducing the size and increasing the efficiency of membranes for gas separations remains unfulfilled due to their poor selectivity. We report an ultrapermeable polymer of intrinsic microporosity (PIM-TMN-Trip) that is substantially more selective than PTMSP. From molecular simulations and experimental measurement we find that the inefficient packing of the two-dimensional (2D) chains of PIM-TMN-Trip generates a high concentration of both small (<0.7 nm) and large (0.7–1.0 nm) micropores, the former enhancing selectivity and the latter permeability. Gas permeability data for PIM-TMN-Trip surpass the 2008 Robeson upper bounds for O
2
/N
2
, H
2
/N
2
, CO
2
/N
2
, H
2
/CH
4
and CO
2
/CH
4
, with the potential for biogas purification and carbon capture demonstrated for relevant gas mixtures. Comparisons between PIM-TMN-Trip and structurally similar polymers with three-dimensional (3D) contorted chains confirm that its additional intrinsic microporosity is generated from the awkward packing of its 2D polymer chains in a 3D amorphous solid. This strategy of shape-directed packing of chains of microporous polymers may be applied to other rigid polymers for gas separations.
Polymer membranes were formed from the inefficient packing of 2D polymer chains in a 3D amorphous solid, forming small and large micropores that enable high gas selectivity and permeability. This strategy may be applied to other polymers.
Journal Article
Explaining Seasonal Fluctuations of Measles in Niger Using Nighttime Lights Imagery
Measles epidemics in West Africa cause a significant proportion of vaccine-preventable childhood mortality. Epidemics are strongly seasonal, but the drivers of these fluctuations are poorly understood, which limits the predictability of outbreaks and the dynamic response to immunization. We show that measles seasonality can be explained by spatiotemporal changes in population density, which we measure by quantifying anthropogenic light from satellite imagery. We find that measles transmission and population density are highly correlated for three cities in Niger. With dynamic epidemic models, we demonstrate that measures of population density are essential for predicting epidemic progression at the city level and improving intervention strategies. In addition to epidemiological applications, the ability to measure fine-scale changes in population density has implications for public health, crisis management, and economic development.
Journal Article
Vaccination strategies for measles control and elimination: time to strengthen local initiatives
Background
Through a combination of strong routine immunization (RI), strategic supplemental immunization activities (SIA) and robust surveillance, numerous countries have been able to approach or achieve measles elimination. The fragility of these achievements has been shown, however, by the resurgence of measles since 2016. We describe trends in routine measles vaccine coverage at national and district level, SIA performance and demographic changes in the three regions with the highest measles burden.
Findings
WHO-UNICEF estimates of immunization coverage show that global coverage of the first dose of measles vaccine has stabilized at 85% from 2015 to 19. In 2000, 17 countries in the WHO African and Eastern Mediterranean regions had measles vaccine coverage below 50%, and although all increased coverage by 2019, at a median of 60%, it remained far below levels needed for elimination. Geospatial estimates show many low coverage districts across Africa and much of the Eastern Mediterranean and southeast Asian regions. A large proportion of children unvaccinated for MCV live in conflict-affected areas with remote rural areas and some urban areas also at risk. Countries with low RI coverage use SIAs frequently, yet the ideal timing and target age range for SIAs vary within countries, and the impact of SIAs has often been mitigated by delays or disruptions. SIAs have not been sufficient to achieve or sustain measles elimination in the countries with weakest routine systems. Demographic changes also affect measles transmission, and their variation between and within countries should be incorporated into strategic planning.
Conclusions
Rebuilding services after the COVID-19 pandemic provides a need and an opportunity to increase community engagement in planning and monitoring services. A broader suite of interventions is needed beyond SIAs. Improved methods for tracking coverage at the individual and community level are needed together with enhanced surveillance. Decision-making needs to be decentralized to develop locally-driven, sustainable strategies for measles control and elimination.
Journal Article
The Receptor-Mediated Endocytosis of Nonspherical Particles
Enveloped viruses and nanosized biomimetic particles for drug and gene delivery enter target cells mainly through receptor-mediated endocytosis. A few models have been presented to elucidate the mechanics of particle engulfment by the cell membrane, showing how size and surface chemico-physical properties favor or oppose internalization. In this work, the effect of particle nonsphericity is addressed considering elliptical cylindrical particles with aspect ratio Γ. Using a continuum energetic approach, three different conditions have been identified: for sufficiently small Γ, the particle is not even wrapped by the cell membrane; for sufficiently large Γ, the particle is partially wrapped (“frustrated endocytosis”); and for intermediate values of Γ, the particle is fully wrapped and eventually internalized. Given the pleomorphism of viruses and the broad spectrum of shapes for nanosized biomimetic particles, the results presented may be of interest to virologists, pharmacologists, toxicologists, and nanotechnologists.
Journal Article
Ezetimibe Added to Statin Therapy after Acute Coronary Syndromes
In this trial, patients with an acute coronary syndrome within the previous 10 days were randomly assigned to simvastatin plus either ezetimibe or placebo. At a median of 6 years, the rate of cardiovascular events was modestly but significantly lower with simvastatin–ezetimibe.
The use of 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins) reduces both low-density lipoprotein (LDL) cholesterol levels and the risk of cardiovascular events in patients with and those without cardiovascular disease.
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Intensive statin therapy, as compared with moderate-dose statin therapy, incrementally lowers LDL cholesterol levels and rates of nonfatal cardiovascular events.
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Because of the residual risk of recurrent cardiovascular events and safety concerns associated with high-dose statin therapy,
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additional lipid-modifying therapies have been sought.
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Ezetimibe targets the Niemann–Pick C1–like 1 (NPC1L1) protein, thereby reducing absorption of cholesterol from the intestine.
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,
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When added to statins, ezetimibe reduces LDL cholesterol . . .
Journal Article
Rationale and design of the effect of evolocumab in patients at high cardiovascular risk without prior myocardial infarction or stroke (VESALIUS-CV) trial
The reduction of low-density lipoprotein cholesterol (LDL-C) with evolocumab, a fully human monoclonal antibody inhibitor of proprotein convertase subtilisin/kexin type 9 (PCSK9i), reduces the risk of major adverse cardiovascular events in patients with established atherosclerotic cardiovascular disease (ASCVD) with a prior MI, prior stroke, or symptomatic peripheral artery disease, with no offsetting safety concerns. The effect of evolocumab on CV outcomes in lower risk patients without a history of MI or stroke has not been explored.
VESALIUS-CV is a randomized, double-blind, placebo-controlled, global clinical trial designed to evaluate the effect of evolocumab on the risk of major cardiovascular events in patients at high cardiovascular risk but without a prior ischemic event. The study population consists of 12,301 patients with atherosclerosis or high-risk diabetes mellitus without a prior MI or stroke; an LDL-C ≥ 90 mg/dL, or non-high-density lipoprotein cholesterol (non-HDL-C) ≥ 120 mg/dL, or apolipoprotein B ≥ 80 mg/dL; and treated with optimized lipid-lowering therapy. Patients were randomized in a 1:1 ratio to evolocumab 140 mg subcutaneously every 2 weeks or matching placebo. The primary efficacy objective is to assess whether evolocumab reduces the risk of the dual primary composite endpoints of coronary heart disease (CHD) death, myocardial infarction (MI), or ischemic stroke (triple primary endpoint) and of CHD death, MI, ischemic stroke, or ischemia-driven arterial revascularization (quadruple primary endpoint). Recruitment began in June 2019 and completed in November 2021. The trial is planned to continue until at least 751 patients experience an adjudicated triple endpoint, at least 1254 experience an adjudicated quadruple endpoint, and the median follow-up is ≥4.5 years.
VESALIUS-CV will determine whether the addition of evolocumab to optimized lipid-lowering therapy reduces cardiovascular events in patients at high cardiovascular risk without a prior MI or stroke.
NCT03872401.
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Journal Article