Non-monotonic Effect Research Articles

Refining acute human exposure assessment to pesticides in surface water: An integrated data-driven modeling approach

The substantial spatial and temporal variability of pesticides has led to large uncertainties when determining their peak aqueous concentrations. There is however a lack of large-scale studies dealing with accurate determination of annual maximum daily concentration (AMDC) across the landscape and over time based on the publicly available monitoring data. We developed a novel data-driven approach that firstly used time series modeling to generate AMDCs for qualified water monitoring sites in the conterminous U.S. With feature variables such as pesticide use and land cover compiled into the dataset, machine learning models using eXtreme Gradient Boosting (XGBoost) and Random Forest Regressor (RF) were then developed to estimate AMDCs in surface waters across the U.S. Both models exhibited significant predictability, while a hybrid model consisting of the average predictions by XGBoost and RF model had the highest prediction accuracy (mean absolute error (MAE): 1.23; R2: 0.61). The analysis of permutation variable importance indicated that pesticide use and drainage area were the two most important drivers. Partial dependence analysis revealed that pesticide use, precipitation, cultivated crop land cover and solubility exhibited concentration-promoting effects, whereas drainage area and molecular weight had concentration-demoting effects. Soil adsorption coefficient (Koc) showed nonmonotonic effects. The hybrid model was used to predict and map AMDCs of four example pesticides, including 2,4-dichlorophenoxyacetic acid (2,4-D), atrazine, glyphosate and imidacloprid during 2016–2019 at national scale. The predictive capability was validated using independent monitoring datasets. The fully evaluated approach significantly reduced the uncertainties in modeling annual peak concentrations and served as a valuable solution for conducting geographically oriented, highly refined exposure assessments for pesticides.

Behaviour of helium and hydrogen in vanadium alloys – innovative fusion reactor first wall materials: a review. Part 1. V – Ti and V – Fe alloys

This paper is the first part of a three-part review that looks at the effect of doping elements on the behaviour of helium, the development of gas porosity, as well as at the amount of retained hydrogen introduced into vanadium alloys with Ti, Cr, W and Ta (using different techniques) with a rapid decay of induced radioactivity. The same regularities have been identified regarding how the chemical composition of the alloys impacts the hydrogen entrapment and retention regardless of the way it is introduced: either through pressure saturation without defect formation or through ion implantation with radiation-induced defects entailed. It was established that when vanadium is doped with a chemically active element (V – Ti alloys), the concentration of the latter has a nonmonotonic effect on the helium porosity and the mass fraction of retained hydrogen. It can be attributed to the way titanium interacts with oxygen and nitrogen in vanadium, which dictates how much titanium hydride will form. The paper demonstrates that pre-irradiation of the alloy with helium ions results in a higher amount of retained hydrogen when it is introduced further, regardless of the temperature.

Experimental investigation of the stability and emission characteristics of premixed formic acid-methane-air flames in a swirl combustor

Formic acid (FA) is a potential hydrogen energy carrier and low-carbon fuel by reversing the decomposition products, CO2 and H2, back to restore FA without additional carbon release. However, FA-air mixtures feature high ignition energy and low flame speed; hence stabilizing FA-air flames in combustion devices is challenging. This study experimentally investigates the flame stability and emission of swirl flames fueled with pre-vaporized formic acid-methane blends over a wide range of formic acid fuel fractions. Results show that by using a swirl combustor, the premixed formic acid-methane-air flames could be stabilized over a wide range of FA fuel fractions, Reynolds numbers, and swirl numbers. The addition of formic acid increases the equivalence ratios at which the flashback and lean blowout occur. When Reynolds number increases, the equivalence ratio at the flashback limit increases, but that decreases at the lean blowout limit. Increasing the swirl number has a non-monotonic effect on stability limits variation because increasing the swirl number changes the axial velocity on the centerline of the burner throat non-monotonically. In addition, emission characteristics were investigated using a gas analyzer. The CO and NO concentrations were below 20 ppm for all tested conditions, which is comparable to that seen with traditional hydrocarbon fuels, which is in favor of future practical applications with formic acid.

A Unified Model of Cohort Mortality.

We propose a dynamic production function of population health and mortality from birth onward. Our parsimonious model provides an excellent fit for the mortality and survival curves for primate and human populations since 1816. The model sheds light on the dynamics behind many phenomena documented in the literature. Simple extensions of the model can reproduce (1) the existence and evolution of mortality gradients across socioeconomic statuses documented in the literature, (2) nonmonotonic dynamic effects of in utero shocks, (3) persistent or scarring effects of wars, and (4) mortality displacement after large temporary shocks, such as extreme weather.

RoSense: Refining LOS Signal Phase for Robust RFID Sensing via Spinning Antenna

RFID sensing leveraging backscatter signal features (e.g., phase shift) from tags has gained increasing popularity in numerous applications but also suffers from negative impacts of environmental multipaths. Past works to address it rely on extra customized devices, labor-intensive offline training, or frequency channel hopping, all of which are non-ubiquitous or ineffective for real-life adoption. This article presents RoSense, a universal method to alleviate multipath reflections’ impacts by spinning the reader antenna, thus enabling more robust RFID sensing. Besides, RoSense requires no RF devices or offline training and operates in a nonintrusive manner. The key insight of RoSense is to exploit two properties of line-of-sight (LOS) signal when spinning the antenna, i.e., the linearity of phase changes and stability of received signal strength to attenuate the nonlinear and nonmonotonic effect of multipath signals and refine the phase shift of LOS signal. We have implemented a prototype of RoSense with COTS devices and studied two cases for evaluation: 1) material identification and 2) object localization. Experimental results show that RoSense can improve the material identification accuracy by up to 16.22% and reduce the mean localization error by up to 39.93%, greatly outperforming the state-of-the-art solutions.

U-shaped impacts of institutional quality and ICT penetration on economic growth: Evidence from selected emerging countries

This research aims to consider determinants of economic growth, such as financial development, institutional quality, and information and communication technology (ICT) penetration, which have been explored separately in previous studies and have produced mixed findings in different regions. Using the two-step system generalized method of moments (GMM) estimator for a dynamic panel dataset of 35 selected emerging countries, several research findings could be drawn as the following. First, both ICT penetration and institutional quality have significantly positive effects on economic growth. On the contrary, economic development could be hampered by financial development. Second, there are the U-shape and inverted U-shape relations for the cases of institutional quality and ICT penetration on economic growth, respectively. Third, the interaction effect of ICT penetration and financial development could enhance economic growth while the negative impact of financial development on economic development is amplified by the high level of institutional quality. These findings are robust to the global financial crisis control and the use of an alternative ICT proxy when setting up the approach of principal component analysis. Given these findings from emerging countries, some policy challenges that policy-makers should address by simultaneously considering each growth driver, such as financial development, ICT evolution, and institutional quality and interactions between them, as well as the non-monotonic effect of ICT penetration and institutional quality to facilitate economic growth. U-shaped impacts of institutional quality and ICT penetration on economic growth: Evidence from selected emerging countriesAll authorsThanh Phuc Nguyen , Thi Thu Hong Dinh, Ngoc Tho Tran & Trang Duong Thi Thuyhttps://doi.org/10.1080/23322039.2022.2139887Published online:04 November 2022Display full size

Characteristic of Spiral Displacement Process in Primary Cementing of Vertical Well Washout

Summary Cementation is an essential process in well drilling, which provides security and isolation for following operations and for wells’ long-life production. Irregularity of the wellbore makes cementing more complex, with displaced fluid becoming easily trapped and leading to poor isolation. Here, we investigated spiral displacement of washout, which is one kind of irregularity, where the spiral flow is induced by a cyclone centralizer. The features of spiral flow with sudden hole enlargement, differences between spiral and nonspiral displacement processes, and influence of some parameters were investigated with a simulation method. First, the induced radial flow is around zero (10−1) of the main flow, which is enough for displacing radially, and this radial flow results in radial migration and dispersion of flow field. Cooperating with reversing flow after hitting the outer wall, radial migration leads to flow field mixing and spiral velocity dissipating quickly along the axial direction. Moreover, spiral flow is beneficial for cementing of washout, and the displacing pattern with spiral flow is different compared with axis flow. In spiral displacement, cement slurry accumulates at the bottom and outer side of the washout, while accumulation happens at the top and inner side of the washout for nonspiral flow. The accumulation pattern in spiral displacement prompts movement of residual fluid, but topside accumulation hinders removal of that. Of these parameters, density difference can depress the elongation of the interface and has a positive effect on displacement. An increase in washout length and diameter has a favorable influence, as such enlargement allows for further development of displacing flow and delays the breakthrough. An increase in displacing velocity and rotation angle has a nonmonotonic effect in that with the displacing velocity increasing, the displacement first worsens, then improves, but increasing the rotation angle has the opposite effect.

Thermal performance of a vapor chamber with synergistic effects of droplet jumping and pillared-wick capillarity

• Thermal performance of jumping-droplet vapor chamber was experimentally studied. • The number of auxiliary wick columns shows nonmonotonic effect on the performance. • Increased inner chamber height reduces thermal resistance and gravity dependence. • Jumping droplets may not directly reach the evaporator surface. • The minimum thermal resistance of the vapor chamber reaches 0.064 K/W. When condensate droplets coalesce on a superhydrophobic surface, the released surface energy may yield the merged droplet to jump off the substrate. Based on such principle, jumping-droplet vapor chamber (JDVC) has been proposed as a novel type of heat spreader for hot spot cooling, while the internal working mechanism is rather complicated and still remains inadequately understood. In the present work, the thermal performance of JDVC with auxiliary capillary pillars were experimentally studied, with particular interest on understanding the synergistic effects of droplet jumping and pillared-wick capillarity. Five JDVC samples were fabricated (with a fixed diameter of 97.6 mm, three different overall chamber heights of 3.4 mm, 3.9 mm and 4.4 mm, and a fixed heating area of 1.5 cm 2 ) to investigate the effect of filling ratio, number of auxiliary wick columns and inner chamber height on performance. Results show that, the thermal resistance shows a non-monotonic variation of “decrease-increase” with increasing filling ratio, with a higher heat flux favoring a higher optimal filling ratio. The temperature homogeneity is improved under bottom heat mode compared to under top heat mode, which could be possibly attributed to the improved efficiency of droplet removal. The number of auxiliary wick columns shows non-monotonic effect of “enhance-suppress” on the thermal performance, suggesting that a moderate number of auxiliary wick columns helps to gather the jumped-off droplets in space and facilitates stable capillary-driven working fluid circulation. Increasing the inner chamber height yields reduced thermal resistance and improved gravity independence, indicating that direct arrival of jumping droplets on the evaporator surface may not be the primary way of working fluid recirculation, otherwise the thermal performance should degrade since less jumping droplets are able to reach a higher evaporator surface. Among the results, the minimum thermal resistance of the vapor chamber reaches 0.064 K/W and the critical heat flux exceeds 253.2 W/cm 2 .

The Other Dimension-Tuning Hole Extraction via Nanorod Width.

Solar-to-hydrogen generation is a promising approach to generate clean and renewable fuel. Nanohybrid structures such as CdSe@CdS-Pt nanorods were found favorable for this task (attaining 100% photon-to-hydrogen production efficiency); yet the rods cannot support overall water splitting. The key limitation seems to be the rate of hole extraction from the semiconductor, jeopardizing both activity and stability. It is suggested that hole extraction might be improved via tuning the rod’s dimensions, specifically the width of the CdS shell around the CdSe seed in which the holes reside. In this contribution, we successfully attain atomic-scale control over the width of CdSe@CdS nanorods, which enables us to verify this hypothesis and explore the intricate influence of shell diameter over hole quenching and photocatalytic activity towards H2 production. A non-monotonic effect of the rod’s diameter is revealed, and the underlying mechanism for this observation is discussed, alongside implications towards the future design of nanoscale photocatalysts.

Emulsions stabilized by asphaltene-polyacrylamide-soil three-phase components: Stabilization mechanism and concentration effects

Polymer oil recovery technology has been widely applied, but the resultant increased polymer-containing oil sludge are facing with treatment difficulties. Internal interactions of oil sludge that contained hydrolyzed polyacrylamide (HPAM) have been not well understood. This study established specific emulsion systems to examine contributions of asphaltenes, soil particles, and HPAM to stabilization of polymer-containing oil sludge. According to emulsification index, emulsion droplet sizes, and emulsion shear rheology analysis, the results show that asphaltenes and soil particles have synergistic effect in stabilizing emulsions. The emulsion with soil particles and asphaltenes exhibited strongest stability, more stable than the emulsion with three-phase components. The surface adsorption of asphaltenes on soil particles enhanced lipophilicity of soil particles. But emulsion stability was weakened due to the flocculation of particles by HPAM. The concentration effect tests prove that high concentrations of soil particles (100–1000 g/L) and asphaltenes (100–300 ppm) can enhance emulsion stability, but HPAM has non-monotonic concentration effect. In addition, strongest emulsion stability was observed at neutral pH. Smaller soil particle size tended to cause high strength emulsion interfacial film forming. These findings benefit the development of “targeted” treatment technologies for polymer-containing oil sludge.

On sticky bookmaking as a learning device in horse-racing betting markets

We present a stochastic dynamic model of the adjustment of betting odds by bookmakers in a horse-racing betting market. We use optimal stopping theory in a two-horse benchmark model with both informed and noise punters. A costly learning process discloses what information the informed traders possess and a risk-neutral bookmaker selects a stopping time at which the betting odds for each horse in a race are adjusted. Our main finding shows that an increased fraction of informed punters has a non-monotonic effect on the loss per trade to the bookmaker. We also find that as the fraction of noise traders goes up, the learning process is less informative, so that the decision to change the prices for each horse is taken sooner.

Concentration-Dependent Effects of Cholesterol on the Dimerization of Amyloid-β Peptides in Lipid Bilayers.

Membrane disruption mediated by the accumulation of amyloid-β (Aβ) on cell membranes is central to the pathogenesis of Alzheimer's disease (AD). Cholesterol, an important component of membranes, is well-recognized as a risk factor in AD. It can affect the aggregation and pore formation of Aβ on membranes whereas the specific effects are rather complex, particularly regarding the non-linear response to cholesterol concentrations. Yet, the mechanistic understanding of the role of cholesterol in Aβ-membrane interactions remains incomplete. Herein, we employed microsecond-scale molecular dynamics simulations to investigate the effects of cholesterol on Aβ dimerization in a lipid bilayer containing different molar ratios of cholesterol (0, 20, and 40 mol %). Cholesterol reduces the time required for the formation of stable dimers and exerts dual effects on Aβ-membrane interactions. First, cholesterol promotes the extraction of the C-terminal region from the membrane to water. Consequently, at the ratios of 0 and 20 mol %, peptides are anchored at the membrane-water interface, but they are repelled to water at a ratio of 40 mol % with high structural flexibility. Second, cholesterol weakens Aβ-membrane interactions, thereby enhancing inter-peptide interactions. The former is favorable for dimerization while the latter is not. The balance between two factors eventually leads to a non-monotonic effect on the degree of dimerization, whereby the number of inter-peptide contacts is the largest at a cholesterol ratio of 20 mol %. These results provide atomistic insights into the regulation mechanism of Aβ42 aggregation by cholesterol and help to understand the pathological link between cholesterol and AD.

Effect of Social Influence on a Two-Party Election: A Markovian Multiagent Model

In digital social networks, the filtering algorithms employed by the platform management to sieve the contents shared among the users can alter the social influence intensity. In this article, a Markov multiagent model of opinion dynamics is used to analyze possible opinion manipulation under apparently neutral interventions on the influence intensity. We consider a two-party election, whose voters, modeled as heterogeneous agents, are connected in a social network with an arbitrary topology. The equations describing the variance of the vote share, both in transient and steady state, are derived. The key is the solution of the second-order marginalization problem under the form of a numerically tractable characterization of pairwise joint probabilities of the voters’ opinions. In particular, these probabilities are computed by means of a Lyapunov-like matrix differential equation driven by first-order moments. This result is used to answer some important questions, like the possible nonmonotonic effect of the influence intensity on the vote volatility and the interplay of topology and individuals’ stubbornness to determine the electoral balance between two parties.

Embryonic exposure to benzo[a]pyrene causes age-dependent behavioral alterations and long-term metabolic dysfunction in zebrafish

Polycyclic aromatic hydrocarbons (PAH) are products of incomplete combustion which are ubiquitous pollutants and constituents of harmful mixtures such as tobacco smoke, petroleum and creosote. Animal studies have shown that these compounds exert developmental toxicity in multiple organ systems, including the nervous system. The relative persistence of or recovery from these effects across the lifespan remain poorly characterized. These studies tested for persistence of neurobehavioral effects in AB* zebrafish exposed 5–120 h post-fertilization to a typical PAH, benzo[a]pyrene (BAP). Study 1 evaluated the neurobehavioral effects of a wide concentration range of BAP (0.02–10 μM) exposures from 5 to 120 hpf during larval (6 days) and adult (6 months) stages of development, while study 2 evaluated neurobehavioral effects of BAP (0.3–3 μM) from 5 to 120 hpf across four stages of development: larval (6 days), adolescence (2.5 months), adulthood (8 months) and late adulthood (14 months). Embryonic BAP exposure caused minimal effects on larval motility, but did cause neurobehavioral changes at later points in life. Embryonic BAP exposure led to nonmonotonic effects on adolescent activity (0.3 μM hyperactive, Study 2), which attenuated with age, as well as startle responses (0.2 μM enhanced, Study 1) at 6 months of age. Similar startle changes were also detected in Study 2 (1.0 μM), though it was observed that the phenotype shifted from reduced pretap activity to enhanced posttap activity from 8 to 14 months of age. Changes in the avoidance (0.02–10 μM, Study 1) and approach (reduced, 0.3 μM, Study 2) of aversive/social cues were also detected, with the latter attenuating from 8 to 14 months of age. Fish from study 2 were maintained into aging (18 months) and evaluated for overall and tissue-specific oxygen consumption to determine whether metabolic processes in the brain and other target organs show altered function in late life based on embryonic PAH toxicity. BAP reduced whole animal oxygen consumption, and overall reductions in total basal, mitochondrial basal, and mitochondrial maximum respiration in target organs, including the brain, liver and heart. The present data show that embryonic BAP exposure can lead to neurobehavioral impairment across the life-span, but that these long-term risks differentially emerge or attenuate as development progresses.

Non-monotonic effect of ethanol concentration on the spreading of an ethanol-water binary droplet impact on a supercooled surface

We investigate the effect of ethanol concentration on the spreading dynamics of an ethanol-water binary droplet impact on a supercooled surface. The maximum spreading factor, comprised of the maximum internal spreading factor and dimensionless fingering length, decreases and then increases with the ethanol concentration. It is attributed to the change in ethanol concentration which varies liquid viscosity and surface tension directly, and surface cooling which lowers the droplet temperature and thus varies liquid properties that further affect droplet spreading. The maximum internal spreading factor which is also non-monotonic with the ethanol concentration dominates the maximum spreading. The heat transfer analysis on droplet spreading shows that the temperature reduction of the droplet from impact to maximum spreading is non-monotonic dependent on the ethanol concentration, while shows different trends with surface cooling at various ethanol concentration. Deviations of the predicated maximum spreading factor, considering the droplet temperature reduction, obtained by reported correlations from the experimental ones in this study could be mainly due to the difficulty in accurately predicting the temperature-dependent spreading boundary layer thickness of the droplet. The maximum spreading time decreases and then increases with the ethanol concentration, while it keeps decreasing with the surface supercooling. A new correlation of the maximum spreading time is proposed by incorporating the coefficient of surface supercooling and capillary-inertial time of the droplet which involves density and surface tension.

Identification of nonmonotonic concentration-responses in Tox21 high-throughput screening estrogen receptor assays

Environmental endocrine-disrupting chemicals (EDCs) interfere with the metabolism and actions of endogenous hormones. It has been well documented in numerous in vivo and in vitro studies that EDCs can exhibit nonmonotonic dose response (NMDR) behaviors. Not conforming to the conventional linear or linear-no-threshold response paradigm, these NMDR relationships pose practical challenges to the risk assessment of EDCs. In the meantime, the endocrine signaling pathways and biological mechanisms underpinning NMDR remain incompletely understood. The US Tox21 program has conducted in vitro cell-based high-throughput screening assays for estrogen receptors (ER), androgen receptors, and other nuclear receptors, and screened the 10 K-compound library for potential endocrine activities. Using 15 concentrations across several orders of magnitude of concentration range and run in both agonist and antagonist modes, these Tox21 assay datasets contain valuable quantitative information that can be explored to evaluate the nonlinear effects of EDCs and may infer potential mechanisms. In this study we analyzed the concentration-response curves (CRCs) in all 8 Tox21 ERα and ERβ assays by developing clustering and classification algorithms customized to the datasets to identify various shapes of CRCs. After excluding NMDR curves likely caused by cytotoxicity, luciferase inhibition, or autofluorescence, hundreds of compounds were identified to exhibit Bell or U-shaped CRCs. Bell-shaped CRCs are about 7 times more frequent than U-shaped ones in the Tox21 ER assays. Many compounds exhibit NMDR in at least one assay, and some EDCs well-known for their NMDRs in the literature were also identified, suggesting their nonmonotonic effects may originate at cellular levels involving transcriptional ER signaling. The developed computational methods for NMDR identification in ER assays can be adapted and applied to other high-throughput bioassays.

Experimental study and surface complexation modeling of non-monotonic wettability behavior due to change in brine salinity/composition: Insight into anhydrite impurity in carbonates

Wettability alteration as the main mechanism of improved oil recovery in carbonates during low salinity/engineered water flooding (LS/EWF) is a complex phenomenon due to high heterogeneity of rock. During LS/EWF, wettability changes when electrochemical interactions at carbonate-brine interface happen. Anhydrite impurity in carbonates is one of the most important parameters affecting the electrochemical interactions at the rock-brine interface and the wettability alteration process. Therefore, the success of LS/EWF in carbonate reservoirs lies in perceiving the role of impurities such as anhydrite, from a geochemical and dissolution point of view.Modified flotation tests (MFT) were performed on two rock samples (calcite and a mixture of calcite and 10 wt% of anhydrite) to assess the wettability alteration which showed a non-monotonic wettability effect as the presence of anhydrite lowered the optimum salinity from 10-times diluted seawater (SW/10) to SW/25. Mineral dissolution and zeta potential measurement showed no comprehensive correlation with the wettability state of particles obtained from MFTs. To resolve this challenge, a diffuse double layer (DDL) based surface complexation model (SCM) was developed using PHREEQC geochemical package to shed light on the anhydrite role during the desorption of oil acidic components from the rock surface imposed on various brines. The model was validated using measured zeta potential. The DDL-based SCM proposed an anhydrite dominant window in which the presence of anhydrite, its dissolution, and in-situ supply of SO42-, lead to altering the wettability to more water wetness.This work is significant to explain the effect of anhydrite impurity on the performance of low salinity water injection using experimental data and DDL-based SCM, while the simple techniques of rock dissolution and zeta potential are not able to justify the non-monotonic behavior of wettability of the carbonates. Also, it introduces a new quantitative parameter of the wettability state of carbonate surface by considering the adsorbed carboxylic acid components on the calcite surface reported by SCM.

Pricing and quality decisions with conspicuous consumers

With the growing demand of individuality, conspicuous consumption has gradually become a common phenomenon. This study focuses on how conspicuous consumption affects firm’s pricing, quality decisions and profit. By developing a game-theoretic model consisting of one monopolist who sells a conspicuously consumed status product and two segments of consumers, i.e., conspicuous consumers and non-conspicuous consumers (the former are less sensitive to price than the latter), we come to the following results. Firstly, the presence of conspicuous consumers benefits the firm by leading to higher quality and price when their price sensitivity is relatively low, while can hurt the firm by leading to lower quality and price regardless of the proportion of conspicuous consumers and the conspicuousness degree when their price sensitivity is quite high. Secondly, for a moderate price sensitivity, we find an interesting result that the proportion of conspicuous consumers shows a non-monotonic effect on the firm’s profit. Specifically, the firm’s profit increases (decreases) with the proportion of conspicuous consumers when the quality investment efficiency is high (low) and the conspicuousness degree is low (high), while the profit decreases first and then increases for those medium quality investment efficiency and conspicuousness degree. Furthermore, we find that the joint decisions on quality and price exhibit strategic complementarity. Finally, the robustness of the results obtained is verified in numerous model extensions.

Competition between CO2-philicity and Mixing Entropy Leads to CO2 Solubility Maximum in Polyether Polyols.

In carbon dioxide-blown polymer foams, the solubility of carbon dioxide (CO2) in the polymer profoundly shapes the structure and, consequently, the physical properties of the foam. One such foam is polyurethane—commonly used for thermal insulation, acoustic insulation, and cushioning—which increasingly relies on CO2 to replace environmentally harmful blowing agents. Polyurethane is produced through the reaction of isocyanate and polyol, of which the polyol has the higher capacity for dissolving CO2. While previous studies have suggested the importance of the effect of hydroxyl end groups on CO2 solubility in short polyols (<1000 g/mol), their effect in polyols with higher molecular weight (≥1000 g/mol) and higher functionality (>2 hydroxyls per chain)—as are commonly used in polyurethane foams—has not been reported. Here, we show that the solubility of CO2 in polyether polyols decreases with molecular weight above 1000 g/mol and decreases with functionality using measurements performed by gravimetry-axisymmetric drop-shape analysis. The nonmonotonic effect of molecular weight on CO2 solubility results from the competition between effects that reduce CO2 solubility (lower mixing entropy) and effects that increase CO2 solubility (lower ratio of hydroxyl end groups to ether backbone groups). To generalize our measurements, we modeled the CO2 solubility using a perturbed chain-statistical associating fluid theory (PC-SAFT) model, which we validated by showing that a density functional theory model based on the PC-SAFT free energy accurately predicted the interfacial tension.

Association between per- and polyfluoroalkyl substances exposure and risk of diabetes: a systematic review and meta-analysis.

Emerging evidence suggests that per- and polyfluoroalkyl substances (PFAS) are endocrine disruptors and may contribute to the etiology of diabetes. This study aimed to systematically review the epidemiological evidence on the associations of PFAS with mortality and morbidity of diabetes and to quantitatively evaluate the summary effect estimates of the existing literature. We searched three electronic databases for epidemiological studies concerning PFAS and diabetes published before April 1, 2022. Summary odds ratio (OR), hazard ratio (HR), or β and their 95% confidence intervals (CIs) were respectively calculated to evaluate the association between PFAS and diabetes using random-effects model by the exposure type, and dose-response meta-analyses were also performed when possible. We also assessed the risk of bias of the studies included and the confidence in the body of evidence. An initial literature search identified 1969 studies, of which 22 studies were eventually included. The meta-analyses indicated that the observed statistically significant PFAS-T2DM associations were consistent in cohort studies, while the associations were almost non-significant in case-control and cross-sectional studies. Dose-response meta-analysis showed a "parabolic-shaped" association between perfluorooctanoate acid (PFOA) exposure and T2DM risk. Available evidence was rated with "low" risk of bias, and the level of evidence for PFAS and incident T2DM was considered "moderate". Our findings suggest that PFAS exposure may increase the risk of incident T2DM, and that PFOA may exert non-monotonic dose-response effect on T2DM risk. Considering the widespread exposure, persistence, and potential for adverse health effects of PFAS, further cohort studies with improvements in expanding the sample size, adjusting the covariates, and considering different types of PFAS exposure at various doses, are needed to elucidate the putative causal associations and potential mode of action of different PFAS on diabetes. A growing body of evidence suggests that per- and polyfluoroalkyl substances (PFAS) are endocrine disruptors and may contribute to the development of diabetes. However, epidemiological evidence on the associations of PFAS and diabetes is inconsistent. We performed this comprehensive systematic review and meta-analysis to quantitatively synthesize the evidence. The findings of this study suggest that exposure to PFAS may increase diabetes risk among the general population. Reduced exposure to these "forever and everywhere chemicals" may be an important preventative approach to reducing the risk of diabetes across the population.