Morphology controls the thermoelectric power factor of a doped semiconducting polymer

The electrical performance of doped semiconducting polymers is strongly governed by processing methods and underlying thin-film microstructure. We report on the influence of different doping methods (solution versus vapor) on the thermoelectric power factor (PF) of PBTTT molecularly p-doped with FnTCNQ (n = 2 or 4). The vapor-doped films have more than two orders of magnitude higher electronic conductivity (s) relative to solution-doped films. On the basis of resonant soft x-ray scattering, vapor-doped samples are shown to have a large orientational correlation length (OCL) (that is, length scale of aligned backbones) that correlates to a high apparent charge carrier mobility (m). The Seebeck coefficient (a) is largely independent of OCL. This reveals that, unlike s, leveraging strategies to improve m have a smaller impact on a. Our best-performing sample with the largest OCL, vapor-doped PBTTT: F4TCNQ thin film, has a s of 670 S/cm and an a of 42 μV/K, which translates to a large PF of 120 mW m-1 K-2. In addition, despite the unfavorable offset for charge transfer, doping by F2TCNQ also leads to a large PF of 70 μW m-1 K-2, which reveals the potential utility of weak molecular dopants. Overall, our work introduces important general processing guidelines for the continued development of doped semiconducting polymers for thermoelectrics

The dopamine D2 receptor mediates approach-avoidance tendencies in smokers

Dopamine D2 receptors (DRD2) have been strongly implicated in reward processing of natural stimuli and drugs. By using the Approach-Avoidance Task (AAT), we recently demonstrated that smokers show an increased approach bias toward smoking-related cues but not toward naturally-rewarding stimuli. Here we examined the contribution of the DRD2 Taq1B polymorphism to smokers’ and non-smokers’ responsivity toward smoking versus naturally-rewarding stimuli in the AAT. Smokers carrying the minor B1 allele of the DRD2 Taq1B polymorphism showed reduced approach behavior for food-related pictures compared to non-smokers with the same allele. In the group of smokers, a higher approach-bias toward smoking-related compared to food-related pictures was found in carriers of the B1 allele. This pattern was not evident in smokers homozygous for the B2 allele. Additionally, smokers with the B1 allele reported fewer attempts to quit smoking relative to smokers homozygous for the B2 allele. This is the first study demonstrating that behavioral shifts in response to smoking relative to natural rewards in smokers are mediated by the DRD2 Taq1B polymorphism. Our results indicate a reduced natural-reward brain reactivity in smokers with a genetically determined decrease in dopaminergic activity (i.e., reduction of DRD2 availability). It remains to be determined whether this pattern might be related to a different outcome after psychological cessation interventions, i.e. AAT modification paradigms, in smokers

Longitudinal observation and decline of neutralizing antibody responses in the three months following SARS-CoV-2 infection in humans

Antibody responses to SARS-CoV-2 can be detected in most infected individuals 10–15 d after the onset of COVID-19 symptoms. However, due to the recent emergence of SARS-CoV-2 in the human population, it is not known how long antibody responses will be maintained or whether they will provide protection from reinfection. Using sequential serum samples collected up to 94 d post onset of symptoms (POS) from 65 individuals with real-time quantitative PCR-confirmed SARS-CoV-2 infection, we show seroconversion (immunoglobulin (Ig)M, IgA, IgG) in >95% of cases and neutralizing antibody responses when sampled beyond 8 d POS. We show that the kinetics of the neutralizing antibody response is typical of an acute viral infection, with declining neutralizing antibody titres observed after an initial peak, and that the magnitude of this peak is dependent on disease severity. Although some individuals with high peak infective dose (ID50 > 10,000) maintained neutralizing antibody titres >1,000 at >60 d POS, some with lower peak ID50 had neutralizing antibody titres approaching baseline within the follow-up period. A similar decline in neutralizing antibody titres was observed in a cohort of 31 seropositive healthcare workers. The present study has important implications when considering widespread serological testing and antibody protection against reinfection with SARS-CoV-2, and may suggest that vaccine boosters are required to provide long-lasting protection

Primitive layered gabbros from fast-spreading lower oceanic crust

Three-quarters of the oceanic crust formed at fast-spreading ridges is composed of plutonic rocks whose mineral assemblages, textures and compositions record the history of melt transport and crystallization between the mantle and the sea floor. Despite the importance of these rocks, sampling them in situ is extremely challenging owing to the overlying dykes and lavas. This means that models for understanding the formation of the lower crust are based largely on geophysical studies and ancient analogues (ophiolites) that did not form at typical mid-ocean ridges. Here we describe cored intervals of primitive, modally layered gabbroic rocks from the lower plutonic crust formed at a fast-spreading ridge, sampled by the Integrated Ocean Drilling Program at the Hess Deep rift. Centimetre-scale, modally layered rocks, some of which have a strong layering-parallel foliation, confirm a long-held belief that such rocks are a key constituent of the lower oceanic crust formed at fast-spreading ridges. Geochemical analysis of these primitive lower plutonic rocks-in combination with previous geochemical data for shallow-level plutonic rocks, sheeted dykes and lavas-provides the most completely constrained estimate of the bulk composition of fast-spreading oceanic crust so far. Simple crystallization models using this bulk crustal composition as the parental melt accurately predict the bulk composition of both the lavas and the plutonic rocks. However, the recovered plutonic rocks show early crystallization of orthopyroxene, which is not predicted by current models of melt extraction from the mantle and mid-ocean-ridge basalt differentiation. The simplest explanation of this observation is that compositionally diverse melts are extracted from the mantle and partly crystallize before mixing to produce the more homogeneous magmas that erupt

Role of Crystallization in the Morphology of Polymer:Non-fullerene Acceptor Bulk Heterojunctions

Many high efficiency organic photovoltaics use fullerene-based acceptors despite their high production cost, weak optical absorption in the visible range, and limited synthetic variability of electronic and optical properties. To circumvent this deficiency, non-fullerene small-molecule acceptors have been developed that have good synthetic flexibility, allowing for precise tuning of optoelectronic properties, leading to enhanced absorption of the solar spectrum and increased open-circuit voltages (<i>V</i>_OC). We examined the detailed morphology of bulk heterojunctions of poly­(3-hexyl­thio­phene) and the small-molecule acceptor HPI-BT to reveal structural changes that lead to improvements in the fill factor of solar cells upon thermal annealing. The kinetics of the phase transformation process of HPI-BT during thermal annealing were investigated through <i>in situ</i> grazing incidence wide-angle X-ray scattering studies, atomic force microscopy, and transmission electron microscopy. The HPI-BT acceptor crystallizes during film formation to form micron-sized domains embedded within the film center and a donor rich capping layer at the cathode interface reducing efficient charge extraction. Thermal annealing changes the surface composition and improves charge extraction. This study reveals the need for complementary methods to investigate the morphology of BHJs

High conductivity in a nonplanar n-doped ambipolar semiconducting polymer

n-Doping of P(BTP-DPP) with the organometallic dimer (RuCp*mes)(2), processed through sequential casting, is reported. Maximum conductivities of 0.45 S cm(-1) were achieved that are relatively high for n-type semiconducting polymers. Electron paramagnetic resonance spectroscopy, ultraviolet visible spectroscopy, and ultraviolet photoemission spectroscopy are consistent with the introduction of high carrier concentrations by sequential processing, leading to bipolaronic, or otherwise spin-paired carriers. P(BTP-DPP) has glassy ordering in thin films, observed using wide angle X-ray scattering, that allows efficient incorporation of the dopant as a function of processing condition. The changes in electrical conductivity as a function of the dopant concentration are proposed to occur by charge percolation through domains with a mixture of polaronic and bipolaronic carriers

Highly Organized Smectic-like Packing in Vapor-Deposited Glasses of a Liquid Crystal

Glasses of a model smectic liquid crystal-forming molecule, itraconazole, were prepared by vapor deposition onto substrates with temperatures ranging from <i>T</i>_substrate = 0.78<i>T</i>_g to 1.02<i>T</i>_g, where <i>T</i>_g (=330 K) is the glass transition temperature. The films were characterized using X-ray scattering techniques. For <i>T</i>_substrate near and below <i>T</i>_g, glasses with layered smectic-like structures can be prepared and the layer spacing can be tuned by 16% through the choice of <i>T</i>_substrate. Remarkably, glasses prepared with <i>T</i>_substrate values above <i>T</i>_g exhibit levels of structural organization much higher than that of a thermally annealed film. These results are explained by a mechanism based upon a preferred molecular orientation and enhanced molecular motion at the free surface, indicating that molecular organization in the glass is independent of the anchoring preferred at the substrate. These results suggest new strategies for optimizing molecular packing within active layers of organic electronic and optoelectronic devices

High Conductivity in a Nonplanar <i>n</i>‑Doped Ambipolar Semiconducting Polymer

<i>n</i>-Doping of P­(BTP-DPP) with the organometallic dimer (RuCp*mes)₂, processed through sequential casting, is reported. Maximum conductivities of 0.45 S cm^–1 were achieved that are relatively high for <i>n</i>-type semiconducting polymers. Electron paramagnetic resonance spectroscopy, ultraviolet visible spectroscopy, and ultraviolet photoemission spectroscopy are consistent with the introduction of high carrier concentrations by sequential processing, leading to bipolaronic, or otherwise spin-paired carriers. P­(BTP-DPP) has glassy ordering in thin films, observed using wide angle X-ray scattering, that allows efficient incorporation of the dopant as a function of processing condition. The changes in electrical conductivity as a function of the dopant concentration are proposed to occur by charge percolation through domains with a mixture of polaronic and bipolaronic carriers

Associations between IgG antibody responses and CHMI outcome measures.

<p>Associations are reported between anti-MSP1₁₉ or anti-AMA1 total IgG ELISA titer readouts at various time-points and/or fold-change post-CHMI (as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0107903#pone-0107903-g001" target="_blank">Figure 1E</a>), as well as with time to malaria diagnosis by thick-film microscopy during CHMI, and parasitemia at time of diagnosis (measured by qPCR in terms of parasites/mL blood). In all cases, Spearman’s rank correlation coefficient and <i>P</i> value are shown. n/a = not applicable; n.d. = not done. *For these analyses, relevant vaccine groups were included: for the MSP1₁₉ analysis, data were combined from the MSP1-only vaccination group and from the MSP1+AMA1 and MSP1+ME-TRAP co-administration groups; and for the AMA1 analysis data were combined from the AMA1-only vaccination group and from the MSP1+AMA1 co-administration group.</p><p>Associations between IgG antibody responses and CHMI outcome measures.</p