As an emerging persistent organic pollutant (POP), perfluorooctanoate (PFOA) is one of the most abundant perfluorinated compounds (PFCs) in the environment. This review summarized the molecular ...mechanisms and signaling pathways of PFOA-induced toxicity in animals and humans as well as their implications for health risks in humans. Traditional PFOA-induced signal pathways such as peroxisome proliferating receptor alpha (PPARα), constitutive androstane receptor (CAR), farnesoid X receptor (FXR), and pregnane-X receptor (PXR) may not be important for PFOA-induced health effects on humans. Instead, pathways including p53/mitochondrial pathway, nuclear lipid hyperaccumulation, phosphatidylinositol 3-kinase-serine/threonine protein kinase (PI3K-AKT), and tumor necrosis factor-α/nuclear factor κB (TNF-α/NF-κB) may play an important role for PFOA-induced health risks in humans. Both in vivo and in vitro studies are needed to better understand the PFOA-induced toxicity mechanisms as well as the associated health risk in humans.
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•Focused on emerging persistent organic pollutant perfluorooctanoate (PFOA)•Showed various toxicity evidence of PFOA exposure in animals and humans•Discussed molecular mechanisms of PFOA-induced health risks in humans•Traditional signal pathways include PPARα, CAR, and PXR•New pathways are mitochondrial pathway, nuclear lipid hyperaccumulation & TNF-α/κB
We compute quasilinear diffusion rates due to pitch angle scattering by various mechanisms in the Earth's electron radiation belts. The calculated theoretical lifetimes are compared with observed ...decay rates, and we find excellent qualitative agreement between the two. The overall structure of the observed lifetime profiles as a function of energy and
L is largely due to plasmaspheric hiss and Coulomb scattering. The results also reveal a local minimum in lifetimes in the inner zone at lower energy (
∼50 keV), attributed to enhanced scattering via ground‐based very low frequency transmitters, and a reduction in lifetimes at higher
L and energy (
>1 MeV), attributed to enhanced electromagnetic ion cyclotron wave scattering. In addition, we find significant quantitative disagreement at
L<3.5, where the theoretical lifetimes are typically a factor of
∼10 larger than the observed, pointing to an additional loss process that is missing from current models. We discuss potential factors that could contribute to this disagreement.
Plain Language Summary
The Earth is surrounded by two invisible, donut‐shaped belts of charged particle radiation (think electrons and protons) called the Van Allen belts. The particles in these belts orbit rapidly around the Earth in the same region where spacecraft fly, like GPS and weather satellites. Since the particles in the belts can damage satellites, we need to understand what specific processes make the intensity of the belts go up and down. Knowing which processes are important for changing the belt intensity helps us build better computer models that can be used to predict the future state of the belts (much like weather prediction models). This letter, along with a companion letter, examines the processes that make the belt intensity go down. We use both spacecraft observations and theoretical calculations to determine which of these “loss” processes are the most important. One particularly interesting result is that we show that high‐powered radio wave transmitters that are used to communicate with submarines can enhance the loss of particles from the inner belt.
Key Points
Electron scattering by Coulomb collisions, hiss, EMIC, and VLF transmitter waves is demonstrated in observed loss timescales
The energy‐
L structure of the observed electron lifetimes is in excellent qualitative agreement with quasilinear theory
Theoretical lifetimes in the inner region (
L<3.5) are much longer than the observed (1,000 vs. 100 days), pointing to a missing loss process
Purpose
Acrylamide (AA) is a potential carcinogen that mainly comes from fried, baked and roasted foods, and Hb adducts of AA (HbAA) and its metabolite glycidamide (HbGA) are the biomarkers of its ...exposure. Increasing evidence suggests that AA is associated with various hormone-related cancers. This study aims to explore the association of HbAA and HbGA with female serum sex hormone concentrations.
Methods
942 women from the National Health and Nutrition Examination Survey cycles (2013–2016) were included in this cross-sectional study. The associations between HbAA or HbGA or HbGA/HbAA and sex hormones were assessed by the multiple linear regression. Further stratified analyses were conducted to figure out the effects of menopausal status, BMI and smoking status on sex hormone levels.
Results
Among all participants, 597 were premenopausal and 345 were postmenopausal. HbAA was positively associated with both two androgen indicators. Specifically, a ln-unit increase in HbAA was associated with 0.41 ng/dL higher ln(total testosterone, TT) (95% CI 0.00, 0.27) and 0.14 ng/dL higher ln(free testosterone) (95%CI 0.00, 0.28), respectively. However, HbGA concentrations had no association with sex hormones in the overall population. Additionally, HbGA/HbAA was negatively associated with TT and SHBG in the overall population as well as postmenopausal women. In stratified analysis, higher HbAA was associated with rising TT in postmenopausal women (
β
= 0.29, 95%CI 0.04, 0.53) and underweight/normal-weight women (
β
= 0.18, 95%CI 0.03, 0.33). Other indicators had no significant association detected in estradiol and sex hormone-binding globulin.
Conclusion
Our results revealed that HbAA was positively associated with androgen concentrations, especially in postmenopausal and BMI < 25 women.
In this study, 46 PM2.5 samples collected from Nanjing, China were analyzed for total PAH concentration, with 14 samples assessed for PAH inhalation bioaccessibility and dioxin toxicity. The ...concentration of 19 PAH compounds in PM2.5 ranged from 4.03 to 102 ng m−3. When PAH inhalation bioaccessibility was assessed using simulated epithelial lung fluid, mean bioaccessibility values ranged from 3.21% (Benzo(c)fluorene) to 44.2% (Acenaphthylene). Benzo(a)pyrene concentration in 50% of the PM2.5 samples exceeded the Chinese air quality standard of 2.5 ng m−3, however, when bioaccessibility was considered, all samples were below the criterion. Similarly, the cancer risk probability for all PM2.5 samples was >10−4 incidences on the basis of total PAH concentration, while only 37% of samples posed a risk >10−4 after incorporation of bioaccessibility. Dioxin toxicity of PM2.5-bound PAHs was also investigated by characterizing mRNA expression of cytochrome P450 superfamily members in human lung cells (A549 cell). Compared to total PAH concentration, the use of bioaccessible concentration was better at predicting dioxin toxicity of PM2.5-associated PAHs (correlation coefficient R2 = 0.40–0.83 with p < 0.05). This study indicates that PAH inhalation bioaccessibility is an important consideration when assessing and predicting the risk posed by PM2.5 particles, which is particularly important for countries with deteriorating air quality.
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•Inhalation bioaccessibility of PM2.5-associated PAHs was measured by simulated epithelial lung fluid.•Life time cancer risk posed by PM2.5-associated PAHs was calculated with PAH inhalation bioaccessibility.•Bioaccessible concentration of PAHs can better predict toxicity posed by PM2.5-associated PAHs.
Summary
Background
Obesity, a comorbid medical condition, is usually observed in patients with established coronary artery disease. Paradoxically, patients with a higher body mass index (BMI) usually ...have better clinical outcomes after coronary revascularization.
Methods
We searched five online databases through December 2017. We identified studies reporting the rate of all‐cause mortality or cardiovascular‐related outcomes among patients after coronary revascularization with percutaneous coronary intervention or coronary artery bypass graft based on various BMI categories. Network meta‐analysis was performed using Bayesian methods.
Results
Sixty‐five records involving 865,774 participants were included in our study. A U‐shaped association was observed across BMI categories for all‐cause mortality. Using normal weight as the reference, all‐cause mortality was increased for (relative risk RR: 2.4; 95% credibility interval CrI: 2.1–2.7) patients with underweight, whereas it was lowered in patients with overweight, obese, and severely obese. This association remained significant in many subgroups. We also observed that the risk of major adverse cardiovascular events (MACE) was lowest among patients with overweight. Furthermore, patients with underweight were associated with greater risks of myocardial infarction (RR: 1.9; 95% CrI: 1.4–2.5), cardiovascular‐related mortality (RR: 2.8; 95% CrI: 1.6–4.7), stroke (RR: 2.0; 95% CrI: 1.3–3.3) and heart failure (RR: 1.7; 95% CrI: 1.1–2.7) compared with normal weight patients; no significant association was observed among individuals with higher BMI.
Conclusions
The ‘obesity paradox’ does exist in patients after coronary revascularization, especially for patients with post‐percutaneous coronary intervention. All‐cause mortality in patients with high BMI is significantly lower compared with patients with normal weight. Furthermore, patients with underweight experience higher rates of cardiovascular outcomes compared with patients with normal weight.
Hexagonal boron nitride (h-BN) is a natural hyperbolic material, in which the dielectric constants are the same in the basal plane (ε(t) ≡ ε(x) = ε(y)) but have opposite signs (ε(t)ε(z) < 0) in the ...normal plane (ε(z)). Owing to this property, finite-thickness slabs of h-BN act as multimode waveguides for the propagation of hyperbolic phonon polaritons--collective modes that originate from the coupling between photons and electric dipoles in phonons. However, control of these hyperbolic phonon polaritons modes has remained challenging, mostly because their electrodynamic properties are dictated by the crystal lattice of h-BN. Here we show, by direct nano-infrared imaging, that these hyperbolic polaritons can be effectively modulated in a van der Waals heterostructure composed of monolayer graphene on h-BN. Tunability originates from the hybridization of surface plasmon polaritons in graphene with hyperbolic phonon polaritons in h-BN, so that the eigenmodes of the graphene/h-BN heterostructure are hyperbolic plasmon-phonon polaritons. The hyperbolic plasmon-phonon polaritons in graphene/h-BN suffer little from ohmic losses, making their propagation length 1.5-2.0 times greater than that of hyperbolic phonon polaritons in h-BN. The hyperbolic plasmon-phonon polaritons possess the combined virtues of surface plasmon polaritons in graphene and hyperbolic phonon polaritons in h-BN. Therefore, graphene/h-BN can be classified as an electromagnetic metamaterial as the resulting properties of these devices are not present in its constituent elements alone.
Uniaxial materials whose axial and tangential permittivities have opposite signs are referred to as indefinite or hyperbolic media. In such materials, light propagation is unusual leading to novel ...and often non-intuitive optical phenomena. Here we report infrared nano-imaging experiments demonstrating that crystals of hexagonal boron nitride, a natural mid-infrared hyperbolic material, can act as a 'hyper-focusing lens' and as a multi-mode waveguide. The lensing is manifested by subdiffractional focusing of phonon-polaritons launched by metallic disks underneath the hexagonal boron nitride crystal. The waveguiding is revealed through the modal analysis of the periodic patterns observed around such launchers and near the sample edges. Our work opens new opportunities for anisotropic layered insulators in infrared nanophotonics complementing and potentially surpassing concurrent artificial hyperbolic materials with lower losses and higher optical localization.
van der Waals heterostructures assembled from atomically thin crystalline layers of diverse two-dimensional solids are emerging as a new paradigm in the physics of materials. We used infrared ...nanoimaging to study the properties of surface phonon polaritons in a representative van der Waals crystal, hexagonal boron nitride. We launched, detected, and imaged the polaritonic waves in real space and altered their wavelength by varying the number of crystal layers in our specimens. The measured dispersion of polaritonic waves was shown to be governed by the crystal thickness according to a scaling law that persists down to a few atomic layers. Our results are likely to hold true in other polar van der Waals crystals and may lead to new functionalities.
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