The association between residential greenspace and preterm birth (PTB) risk remained inconclusive. The PTB subtypes have been ignored and the effect of co-exposure of PM2.5 on PTB risk is still ...unclear.
To investigate the independent, interactive, and mixed effects of residential greenspace and PM2.5 on the risk of PTB subtypes.
A total of 19,900 singleton births from 20 hospitals in Shanghai, China, from 2015 to 2017 were included. The Normalized Difference Vegetation Index (NDVI) within 500 m and 1000 m buffers of the maternal residence and a combined geoscience-statistical model-derived PM2.5 and its six components were used as the exposure measures. PTB (<37 completed weeks of gestation) were divided into early PTB (24–33 weeks) vs. late PTB (34–36 weeks) and into spontaneous PTB (sPTB), preterm premature rupture of the fetal membranes (PPROM), and iatrogenic PTB. Multivariable logistic regression models were applied to assess the independent and interactive effects of NDVI and PM2.5 on PTB in each trimester. The quantile g-computation approach was employed to explore the mixture effect of PM2.5 components and greenspace across the pregnancy and to determine the main contributors.
Levels of PM2.5 and greenspace were associated with increased aOR (95%CI) ranging from 1.18 (1.07, 1.30) to 3.36 (2.45, 4.64) and decreased risks aORs (95%CI) ranging from 0.64 (0.53, 0.78) to 0.86 (0.73, 0.99) of PTB subtypes, respectively. At the same PM2.5 level, higher residential greenspace was associated with lower risks, and vice versa. All these associations were more pronounced in late pregnancy. Early PTB and PPROM were the main affected subtypes, and the main drivers in PM2.5 were black carbon and ammonium.
Residential greenspace may mitigate the PTB risks due to PM2.5 exposure during pregnancy.
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•Residential greenspace was negatively associated with the risk of preterm birth.•Residential greenspace may mitigate the preterm birth risk due to PM2.5 exposure.•Late pregnancy may be the most susceptive window of greenspace and PM2.5 exposures.•The harmful effect of PM2.5 was mainly driven by black carbon and ammonium.
•We downscaled the coarse spatial resolution of deaths to mitigate ecological bias.•We accounted for confounding, spatial autocorrelation and pre-existing conditions.•We found some evidence of an ...effect of NO2 on COVID-19 mortality.•The effect of long-term PM2.5 exposure remains more uncertain.•Our spatial model captured strong patterns likely reflecting disease spread.
Recent studies suggested a link between long-term exposure to air-pollution and COVID-19 mortality. However, due to their ecological design based on large spatial units, they neglect the strong localised air-pollution patterns, and potentially lead to inadequate confounding adjustment. We investigated the effect of long-term exposure to NO2 and PM2.5 on COVID-19 mortality in England using high geographical resolution. In this nationwide cross-sectional study in England, we included 38,573 COVID-19 deaths up to June 30, 2020 at the Lower Layer Super Output Area level (n = 32,844 small areas). We retrieved averaged NO2 and PM2.5 concentration during 2014–2018 from the Pollution Climate Mapping. We used Bayesian hierarchical models to quantify the effect of air-pollution while adjusting for a series of confounding and spatial autocorrelation. We find a 0.5% (95% credible interval: −0.2%, 1.2%) and 1.4% (95% CrI: −2.1%, 5.1%) increase in COVID-19 mortality risk for every 1 μg/m3 increase in NO2 and PM2.5 respectively, after adjusting for confounding and spatial autocorrelation. This corresponds to a posterior probability of a positive effect equal to 0.93 and 0.78 respectively. The spatial relative risk at LSOA level revealed strong patterns, similar for the different pollutants. This potentially captures the spread of the disease during the first wave of the epidemic. Our study provides some evidence of an effect of long-term NO2 exposure on COVID-19 mortality, while the effect of PM2.5 remains more uncertain.
The localized method is one of the popular approaches in solving large-scale problems in science and engineering. In this paper, we implement the localized method of particular solutions using ...polynomial basis functions for solving various nonlinear problems. To validate our proposed numerical method, we present four numerical examples in regular and irregular domains which are solved by using localized method of particular solution with polynomial basis functions. We compared our numerical method with localized method of particular solutions using multiquadric radial basis function and numerical results clearly show that our numerical method is highly accurate, efficient, and outperformed the method using multiquadric radial basis function.
Driven by the urgent need in practical applications of stimuli-responsive nano-carriers for intracellular drug delivery, the design and development of advanced polymeric micelles capable of ...responding to the intracellular environment (e.g., ions, proteins, enzymes, and pH changes) has represented a promising strategy as well as a new task in this research field during the past decade. To this end, an effective approach has been to incorporate cleavable links into the polymer structure, either to cause a structural change of the delivery systems, or to direct conjugate drug molecules which could be released on the cleavage of the links. The current review highlights the recent advance in this field and focuses on two types of polymeric micelles that can respond to the physiological signals, i.e., intracellular pH- and reduction-sensitive micelles.
•Multimode (SI, PFS & SACI) emissions from six fuels across, three CA50 phasings.•Ethanol in fuel lowered soot PM and particle numbers in all combustion modes.•Size distribution of particulate ...impacted by combustion mode, not fuel property.•Organic carbon PM dominated PM mass in both SI and PFS combustion modes.•Paraffins dominated PFS and SACI HC emissions while olefins most prevalent SI HC.
The U.S. Department of Energy’s Co-Optima initiative has focused on improving fuel economy and vehicle performance while reducing emissions through the simultaneous development of emerging sustainable fuels with beneficial properties and advanced combustion strategies. A major thrust has been the development of advanced compression ignition (ACI) combustion strategies of gasoline range fuels in combination with spark-ignited (SI) combustion in a single engine capable of multi-mode operation to achieve high power density with enhanced part load efficiency. The aim of this study was to further the understanding of how emissions from both ACI and SI strategies operating on the same fuels in the same engine are impacted by different fuel properties. This investigation focused on particulate matter (PM) and gaseous hydrocarbon emissions from 6 different fuels across 3 different combustion modes on the same single-cylinder engine designed for multi-mode operation: SI combustion, partial fuel stratification (PFS), and spark-assisted compression ignition (SACI). In each of these modes, 3 different CA50 phasings were studied such that all 6 fuels could be studied at the same phasings. Three of the six different fuels used were specially formulated in a previous investigation to study the impact of fuel distillation and aromatic content while maintaining the research octane number (RON) and octane sensitivity. Additionally, neat isooctane and two ethanol containing fuels (RD5-87 and Co-Optima E30) were studied. Different fuel and phasing impacts on emissions were observed across the three combustion modes. Fuel properties were found to impact soot PM and particle number more than the CA50 phasing, while the phasing had more impact on NOx emissions. The NOx emissions were reduced in the PFS mode for all fuels compared to SI combustion, but the SACI combustion mode did not reduce NOx emissions. Although PFS produced low soot PM emissions like SI, total PM mass emissions were significantly higher due to large organic carbon (OC) PM mass contribution. Both PFS and SACI had greater particle number emission than SI operation with small nuclei mode particles dominating in PFS compared to large agglomeration particles in SACI.
Amphiphilic random methacrylate copolymers, consisting of poly(ethylene glycol) (PEG) and alkyl pendent groups, undergo reversible single-chain self-folding in water via intramolecular hydrophobic ...interaction, to generate a dynamic unimolecular hydrophobic nanospace, similar in shape but structurally different relative to micelles and microgel star polymers. These copolymers were prepared by the ruthenium-catalyzed living radical copolymerization of a PEG methacrylate (PEGMA) and an alkyl methacrylate (RMA; R, −C n H2n+1, n = 1–18), where copolymer composition, degree of polymerization, and hydrophobic R moiety were varied. Detailed structural and chain-folding characterization has revealed: single-chain folding is favored with the RMA content 20–40 mol % per chain; the hydrophobic inner compartment (or the self-folded structure) is stable even at a high polymer concentration (up to ∼6 wt %); and folded–unfolded transition occurs on addition of methanol or by elevating solution temperature, finally to phase-separation above a lower critical solution temperature.
Polymers showing an upper critical solution temperature (UCST) in water are rare. Recently, the nonionic homopolymer poly(N-acryloyl glycinamide) (poly(NAGA)) has been shown to exhibit a sharp upper ...critical solution temperature in pure water as well as in electrolyte solution. Although poly(NAGA) is known for decades the UCST behavior had not been reported. The first controlled radical polymerization of poly(NAGA) by the RAFT (reversible addition–fragmentation transfer) process was also achieved recently, but no UCST was observed. The present study shows that traces of ionic groups in the polymer prevent phase separation. Failure to notice the UCST in the past was because ionic groups have been introduced unintentionally by either acrylate impurities in the monomer, hydrolysis of the polymer side chains, and/or usage of ionic initiators or chain transfer agents. A synthetic procedure for high purity NAGA monomer free of ionic impurities is reported. It is also shown how to obtain stable aqueous solutions of nonionic poly(NAGA) so that the UCST behavior can be exploited in pure water as well as in a physiological milieu. Further, ultrasensitive differential scanning calorimetry and light scattering were used to get insights into the phase separation mechanism. We believe that this knowledge is transferable to other systems and will greatly accelerate research in the field of macromolecules that feature thermally reversible hydrogen bonding.
In this paper, a closed-form particular solution of polyharmonic splines has been obtained for high order partial differential operators. Instead of using complex derivation, the new particular ...solution is derived simply by adding or subtracting several available particular solutions. The proposed particular solution is further coupled with polynomial basis for numerically solving thin plate problems. The relationship between number of nodes and order of polynomials are fully studied. Numerical examples with irregular domains are presented to demonstrate the effectiveness of the proposed algorithm.
Conducting polymers have been widely used in biomedical applications such as biosensors and tissue engineering but their non-degradability still poses a limitation. Therefore, great attention has ...been directed toward the recently developed degradable and electrically conductive polymers (DECPs). The different strategies for synthesis of degradable and conducting polymers containing conducting oligomers are summarized and discussed here as well as the influence of different macromolecular architectures such as linear, star-shaped, hyperbranched and cross-linked DECPs. Blends and composites of biodegradable and conductive polymers are also discussed. The developing trends and challenges with the design of DECPs are also presented.
Highly ultramicroporous, solution-processable polyimides bearing 9,10-bridgehead-substituted triptycene demonstrated the highest BET surface area reported for polyimides (840 m2 g–1) and several new ...highs in gas selectivity and permeability for hydrogen (1630–3980 barrers, H2/CH4 ∼ 38) and air (230–630 barrers, O2/N2 = 5.5–5.9) separations. Two new dianhydrides bearing 9,10-diethyl- and 9,10-dipropyltriptycenes indicate that the ultramicroporosity is optimized for fast polymeric sieving with the use of short, bulky isopropyl bridgeheads and methyl-substituted diamines (TrMPD, TMPD, and TMBZ) that increase intrachain rigidity. Mechanically, the triptycene-based analogue of a spirobisindane-based polyimide exhibited 50% increases in both tensile strength at break (94 MPa) and elastic modulus (2460 MPa) with corresponding 90% lower elongations at break (6%) likely due to the ability of highly entangled spiro-based chains to unwind. To guide future polyimide design, structure/property relationships are suggested between the geometry of the contortion center, the diamine and bridgehead substituent, and the mechanical, microstructural, and gas transport properties.
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