Chemical changes in PCPDTBT:PCBM solar cells using XPS and TOF-SIMS and use of inverted device structure for improving lifetime performance

Analysis of the degradation routes for poly[(4,4-bis(2-ethylhexyl)-cyclopenta-[2,1-b;3,4-b′]dithiophene)-2,6-diyl-alt-2,1,3-benzothiadiazole-4,7-diyl] (PCPDTBT)-based solar cells under illumination and in the presence of air have been conducted using a combination of X-ray Photoelectron Spectroscopy (XPS), Time-Of-Flight Secondary Ion Mass Spectrometry (TOF-SIMs) and solar cell device data. After ageing, XPS studies show that PCPDTBT appears as an oxygen-containing polymer, with data indicating that a break-up in the aromatic rings, formation of sulphates at the thiophene ring, chain scission in the polymer backbone and also loss of side chains. XPS studies have also been conducted on Phenyl-C71-butyric acid methyl ester (PC71BM) films and show a breakage of the fullerene cage, loss of molecular shape and oxidation of carbon atoms in the fullerene cage and side chains after ageing. XPS studies on active layers blends of PCPDTBT and PCBM also show significant changes in the vertical composition during ageing, with increased enrichment of PCPDTBT observed at the top surface and that the use of a processing additive (ODT) has a negative impact on the morphological stability. Based on these studies, it shown that inverted structures are better suited than non-inverted devices for PCPDTBT:PCBM solar cells. An additional advantage of inverted devices is shown using TOF-SIMS; electrode degradation during ageing experiments leads to migration of indium and tin ions into the active layer in non-inverted devices, but is eliminated for inverted devices.HW would like to thank Bangor University for financial support through his “125 scholarship” from the University. ZD is supported from the “SteelPV” project, which is funded from the EC’s Research Fund for Coal and Steel (RFCS) research programme under grant agreement number RFSR-CT-2014-00014. Finally, JK would like to thank the Royal Academy of Engineering for funding via the Newton Research Collaboration Programme (NRCP/1415/28)

Restoration of kTk_T factorization for low pTp_T hadron hadroproduction

We discuss the applicability of the $k_T$ factorization theorem to low-$p_T$ hadron production in hadron-hadron collision in a simple toy model, which involves only scalar particles and gluons. It has been shown that the $k_T$ factorization for high-$p_T$ hadron hadroproduction is broken by soft gluons in the Glauber region, which are exchanged among a transverse-momentum-dependent (TMD) parton density and other subprocesses of the collision. We explain that the contour of a loop momentum can be deformed away from the Glauber region at low $p_T$, so the above residual infrared divergence is factorized by means of the standard eikonal approximation. The $k_T$ factorization is then restored in the sense that a TMD parton density maintains its universality. Because the resultant Glauber factor is independent of hadron flavors, experimental constraints on its behavior are possible. The $k_T$ factorization can also be restored for the transverse single-spin asymmetry in hadron-hadron collision at low $p_T$ in a similar way, with the residual infrared divergence being factorized into the same Glauber factor.Comment: 12 pages, 2 figures, version to appear in EPJ

Impact of long-term erythromycin therapy on the oropharyngeal microbiome and resistance gene reservoir in non-cystic fibrosis bronchiectasis

Published 18 April 2018Long-term macrolide therapy reduces rates of pulmonary exacerbation in bronchiectasis. However, little is known about the potential for macrolide therapy to alter the composition and function of the oropharyngeal commensal microbiota or to increase the carriage of transmissible antimicrobial resistance. We assessed the effect of long-term erythromycin on oropharyngeal microbiota composition and the carriage of transmissible macrolide resistance genes in 84 adults with bronchiectasis, enrolled in the Bronchiectasis and Low-dose Erythromycin Study (BLESS) 48-week placebo-controlled trial of twice-daily erythromycin ethylsuccinate (400 mg). Oropharyngeal microbiota composition and macrolide resistance gene carriage were determined by 16S rRNA gene amplicon sequencing and quantitative PCR, respectively. Long-term erythromycin treatment was associated with a significant increase in the relative abundance of oropharyngeal Haemophilus parainfluenzae (P = 0.041) and with significant decreases in the relative abundances of Streptococcus pseudopneumoniae (P = 0.024) and Actinomyces odontolyticus (P = 0.027). Validation of the sequencing results by quantitative PCR confirmed a significant decrease in the abundance of Actinomyces spp. (P = 0.046). Erythromycin treatment did not result in a significant increase in the number of subjects who carried erm(A), erm(B), erm(C), erm(F), mef(A/E), and msrA macrolide resistance genes. However, the abundance of erm(B) and mef(A/E) gene copies within carriers who had received erythromycin increased significantly (P < 0.05). Our findings indicate that changes in oropharyngeal microbiota composition resulting from long-term erythromycin treatment are modest and are limited to a discrete group of taxa. Associated increases in levels of transmissible antibiotic resistance genes within the oropharyngeal microbiota highlight the potential for this microbial system to act as a reservoir for resistance.IMPORTANCE Recent demonstrations that long-term macrolide therapy can prevent exacerbations in chronic airways diseases have led to a dramatic increase in their use. However, little is known about the wider, potentially adverse impacts of these treatments. Substantial disruption of the upper airway commensal microbiota might reduce its contribution to host defense and local immune regulation, while increases in macrolide resistance carriage would represent a serious public health concern. Using samples from a randomized controlled trial, we show that low-dose erythromycin given over 48 weeks influences the composition of the oropharyngeal commensal microbiota. We report that macrolide therapy is associated with significant changes in the relative abundances of members of the Actinomyces genus and with significant increases in the carriage of transmissible macrolide resistance. Determining the clinical significance of these changes, relative to treatment benefit, now represents a research priority.Jocelyn M. Choo, Guy C. J. Abell, Rachel Thomson, Lucy Morgan, Grant Waterer, David L. Gordon, Steven L. Taylor, Lex E. X. Leong, Steve L. Wesselingh, Lucy D. Burr, Geraint B. Roger

Association between Perceived Discrimination in Healthcare Settings and HIV Medication Adherence: Mediating Psychosocial Mechanisms

There is insufficient research on the impact of perceived discrimination in healthcare settings on adherence to antiretroviral therapy (ART), particularly among women living with HIV, and even less is known about psychosocial mechanisms that may mediate this association. Cross-sectional analyses were conducted in a sample of 1356 diverse women living with HIV enrolled in the Women’s Interagency HIV Study (WIHS), a multi-center cohort study. Indirect effects analysis with bootstrapping was used to examine the potential mediating roles of internalized stigma and depressive symptoms in the association between perceived discrimination in healthcare settings and ART adherence. Perceived discrimination in healthcare settings was negatively associated with optimal (95% or better) ART adherence (adjusted odds ratio (AOR) = 0.81, p = 0.02, 95% confidence interval (CI) [0.68, 0.97]). Furthermore, internalization of stigma and depressive symptoms mediated the perceived discrimination-adherence association: Serial mediation analyses revealed a significant indirect effect of perceived discrimination in healthcare settings on ART adherence, first through internalized HIV stigma, and then through depressive symptoms (B = − 0.08, SE = 0.02, 95% CI [− 0.12, − 0.04]). Perceiving discrimination in healthcare settings may contribute to internalization of HIV-related stigma, which in turn may lead to depressive symptoms, with downstream adverse effects on ART adherence among women. These findings can guide the design of interventions to reduce discrimination in healthcare settings, as well as interventions targeting psychosocial mechanisms that may impact the ability of women living with HIV to adhere to ART regimens

Synthetic prions with novel strain-specified properties

Prions are infectious proteins that possess multiple self-propagating structures. The information for strains and structural specific barriers appears to be contained exclusively in the folding of the pathological isoform, PrP(Sc). Many recent studies determined that de novo prion strains could be generated in vitro from the structural conversion of recombinant (rec) prion protein (PrP) into amyloidal structures. Our aim was to elucidate the conformational diversity of pathological recPrP amyloids and their biological activities, as well as to gain novel insights in characterizing molecular events involved in mammalian prion conversion and propagation. To this end we generated infectious materials that possess different conformational structures. Our methodology for the prion conversion of recPrP required only purified rec full-length mouse (Mo) PrP and common chemicals. Neither infected brain extracts nor amplified PrP(Sc) were used. Following two different in vitro protocols recMoPrP converted to amyloid fibrils without any seeding factor. Mouse hypothalamic GT1 and neuroblastoma N2a cell lines were infected with these amyloid preparations as fast screening methodology to characterize the infectious materials. Remarkably, a large number of amyloid preparations were able to induce the conformational change of endogenous PrPC to harbor several distinctive proteinase-resistant PrP forms. One such preparation was characterized in vivo habouring a synthetic prion with novel strain specified neuropathological and biochemical properties