Chain-assisted charge transport in semicrystalline conjugated polymers

Charge-carrier transport in a paradigmatic semicrystalline polymer semiconductor (P3HT) is important for both fundamental understanding and applications. In samples with enhanced structural disorder due to ad-hoc point defects, the mobility displays rich behavior as a function of electric field (F) and temperature (T). At low T, the mobility increases with the applied field, but upon further increasing T, the field-dependence becomes shallower. Eventually, at the highest T considered, the slope changes sign and the mobility then decreases with the field. This phenomenon can be interpreted with our model as a result of the competition between intrachain conductive-like transport (which slows on increasing F) and interchain activated transport (which is faster at higher F). The former is controlling at high T where interchain hops are strictly limited to nearest-neighbor monomers on adjacent chains. At low T, instead, interchain hops to distant sites are allowed and control the positive correlation of the mobility with the field.This study was supported by the Winton Programme for the Physics of Sustainability (B.O.C.).This is the author accepted manuscript. The final version is available from ACS at http://dx.doi.org/10.1021/acs.jpcc.6b04714

Effects of inhalable particulate matter on blood coagulation.

BACKGROUND: Particulate matter (PM) exposure has been linked to increased risk of cardiovascular disease, possibly resulting from hypercoagulability and thrombosis. Lung and systemic inflammation resulting from PM inhalation may activate blood coagulation, but mechanisms for PM-related hypercoagulability are still largely unknown. OBJECTIVES: To identify coagulation mechanisms activated by PM in a population with well-characterized exposure. METHODS: We measured prothrombin time (PT), activated partial thromboplastin time, endogenous thrombin potentials (ETPs) with/without exogenous triggers and with/without soluble thrombomodulin, tissue-type plasminogen activator (t-PA) antigen, D-dimer and C-reactive protein (CRP) in 37 workers in a steel production plant with well-characterized exposure to PM with aerodynamic diameter of < 1 mum (PM(1)) and coarse PM (PM(10) - PM(1)). Blood samples were collected from each subject on the first (baseline) and last (postexposure) day of a 4-day work week. We analyzed differences between baseline and postexposure levels using a paired Student's t-test. We fitted multivariate mixed-regression models to estimate the associations of interquartile range PM(1) and coarse PM exposure with parameter levels. RESULTS: None of the parameters showed any significant changes from baseline in postexposure samples. However, exposure levels were associated with shorter PT (beta[PM(1)] = -0.33 s, P = 0.08; beta[PM(coarse)] = - 0.33 s, P = 0.01), and higher ETP without exogenous triggers and with thrombomodulin (beta[PM(1)] = + 99 nm min, P = 0.02; beta[PM(coarse)] = + 66 nm min, P = 0.05), t-PA (beta[PM(1)] = + 0.72 ng mL(-1), P = 0.01; beta[PM(coarse)] = + 0.88 ng mL(-1), P = 0.04), and CRP (beta[PM(1)] = + 0.59 mg L(-1), P = 0.03; beta[PM(coarse)] = + 0.48 mg L(-1), P = 0.01). CONCLUSIONS: PM exposure did not show any short-term effect within the week of the study. The association of PM exposure with PT, ETP and CRP provides some evidence of long-term effects on inflammation and coagulation

Effects of particulate matter on genomic DNA methylation content and iNOS promoter methylation

Background: Altered patterns of gene expression mediate the effects of particulate matter (PM) on human health, but mechanisms through which PM modifies gene expression are largely undetermined. Objectives: We aimed at identifying short- and long-term effects of PM exposure on DNA methylation, a major genomic mechanism of gene expression control, in workers in an electric furnace steel plant with well-characterized exposure to PM with aerodynamic diameters < 10 μm (PM10). Methods: We measured global genomic DNA methylation content estimated in Alu and long interspersed nuclear element-1 (LINE-1) repeated elements, and promoter DNA methylation of iNOS (inducible nitric oxide synthase), a gene suppressed by DNA methylation and induced by PM exposure in blood leukocytes. Quantitative DNA methylation analysis was performed through bisulfite PCR pyrosequencing on blood DNA obtained from 63 workers on the first day of a work week (baseline, after 2 days off work) and after 3 days of work (postexposure). Individual PM10 exposure was between 73.4 and 1,220 μg/m3. Results: Global methylation content estimated in Alu and LINE-1 repeated elements did not show changes in postexposure measures compared with baseline. PM10 exposure levels were negatively associated with methylation in both Alu [β = –0.19 %5-methylcytosine (%5mC); p = 0.04] and LINE-1 [β = –0.34 %5mC; p = 0.04], likely reflecting long-term PM10 effects. iNOS promoter DNA methylation was significantly lower in postexposure blood samples compared with baseline (difference = –0.61 %5mC; p = 0.02). Conclusions: We observed changes in global and gene specific methylation that should be further characterized in future investigations on the effects of PM