609 research outputs found

    Highly efficient fullerene and non-fullerene based ternary organic solar cells incorporating a new tetrathiocin-cored semiconductor

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    A new dual-chain oligothiophene-based organic semiconductor, EH-5T-TTC, is presented. The molecule contains two conjugated chains linked by a fused tetrathiocin core. X-ray crystallography reveals a boat conformation within the 8-membered sulfur heterocycle core and extensive π–π and intermolecular sulfur–sulfur interactions in the bulk, leading to a 2-dimensional structure. This unusual molecule has been studied as a ternary component in organic solar cell blends containing the electron donor PTB7-Th and both fullerene (PC71BM) and non-fullerene acceptors ITIC and EH-IDTBR. By incorporating EH-5T-TTC as a ternary component, the power conversion efficiency of the binary blends containing non-fullerene acceptor increases by 17% (from 7.8% to 9.2%) and by 85% for the binary blend with fullerene acceptor (from 3.3% to 6.3%). Detailed characterisation of the ternary blend systems implies that the ternary small molecule EH-5T-TTC functions differently in polymer:fullerene and polymer:non-fullerene blends and has dual functions of morphology modification and complementary spectral absorption

    Tris-ureas as transmembrane anion transporters

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    Nine tris-urea receptors (L1–L9) have been synthesised and shown to coordinate to a range of anionic guests both by 1H NMR titration techniques and single crystal X-ray structural analysis. The compounds have been shown to be capable of mediating the exchange of chloride and nitrate and also chloride and bicarbonate across POPC or POPC : cholesterol 7 : 3 vesicle bilayer membranes at low transporter loadings. An interesting dependency of anion transport on the nature of the cation is evidence to suggest that a M+/Cl− cotransport process may also contribute to the release of chloride from the vesicles

    Proteomic comparisons of opaque and transparent variants of <i>Streptococcus pneumoniae</i> by two dimensional-differential gel electrophoresis

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    Streptococcus pneumoniae (the pneumococcus) is a human pathogen, accounting for massive global morbidity and mortality. Although asymptomatic colonization of the nasopharynx almost invariably precedes disease, the critical determinants enabling pneumococcal progression from this niche to cause invasive disease are poorly understood. One mechanism proposed to be central to this transition involves opacity phase variation, whereby pneumococci harvested from the nasopharynx are typically transparent, while those simultaneously harvested from the blood are opaque. Here, we used two dimensional-differential gel electrophoresis (2D-DIGE) to compare protein expression profiles of transparent and opaque variants of 3 pneumococcal strains, D39 (serotype 2), WCH43 (serotype 4) and WCH16 (serotype 6A) in vitro. One spot comprising a mixture of capsular polysaccharide biosynthesis protein and other proteins was significantly up-regulated in the opaque phenotype in all 3 strains; other proteins were differentially regulated in a strain-specific manner. We conclude that pneumococcal phase variation is a complex and multifactorial process leading to strain-specific pathogenicity.Melissa H. Chai, Florian Weiland, Richard M. Harvey, Peter Hoffmann, Abiodun D. Ogunniyi, James C. Pato

    Imaging features of foreign body granuloma in the lower extremities mimicking a soft tissue neoplasm

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    Foreign body granuloma is a tissue reaction for retained foreign bodies after skin-penetrating trauma. Detection of retained foreign bodies can be extremely difficult when the patients present with non-specific symptoms such as pain and/or swelling without recognizing a previous trauma. We report three patients of foreign body granulomas in the lower extremities with emphasis placed on their unique clinical and radiological features. The involved sites were the foot, posterior thigh, and posterior lower leg, with wooden splinters in two patients and a fragment of tile in one. Plain radiographs could not reveal the existence of foreign bodies. Magnetic resonance imaging (MRI) showed foreign bodies as low intensities on both T1- and T2-weighted images in two patients, and the surrounding reactive lesion as low to iso intensities on T1- and high intensities on T2-weighted images in all the patients. The peripheral areas of the lesion were strongly enhanced after gadolinium injection. Ultrasound sonography could clearly visualize a foreign body as an echogenic area with posterior acoustic shadowing in one patient. The surrounding ring-like reactive lesion is easily mistaken for a soft tissue neoplasm when foreign bodies are not identified. The key to arriving at the correct diagnosis is to clarify the previous trauma and to identify foreign bodies with low signal intensities on both T1- and T2-weighted images and/or the characteristic ring-like enhancement on MRI. It is also necessary to rule out a foreign body granuloma whenever we see patients with a soft tissue tumor in the extremities, irrespective of their previous trauma history

    Verified and potential pathogens of predatory mites (Acari: Phytoseiidae)

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    Several species of phytoseiid mites (Acari: Phytoseiidae), including species of the genera Amblyseius, Galendromus, Metaseiulus, Neoseiulus, Phytoseiulus and Typhlodromus, are currently reared for biological control of various crop pests and/or as model organisms for the study of predator¿prey interactions. Pathogen-free phytoseiid mites are important to obtain high efficacy in biological pest control and to get reliable data in mite research, as pathogens may affect the performance of their host or alter their reproduction and behaviour. Potential and verified pathogens have been reported for phytoseiid mites during the past 25 years. The present review provides an overview, including potential pathogens with unknown host effects (17 reports), endosymbiotic Wolbachia (seven reports), other bacteria (including Cardinium and Spiroplasma) (four reports), cases of unidentified diseases (three reports) and cases of verified pathogens (six reports). From the latter group four reports refer to Microsporidia, one to a fungus and one to a bacterium. Only five entities have been studied in detail, including Wolbachia infecting seven predatory mite species, other endosymbiotic bacteria infecting Metaseiulus (Galendromus, Typhlodromus) occidentalis (Nesbitt), the bacterium Acaricomes phytoseiuli infecting Phytoseiulus persimilis Athias-Henriot, the microsporidium Microsporidium phytoseiuli infecting P. persimilis and the microsporidium Oligosproridium occidentalis infecting M. occidentalis. In four cases (Wolbachia, A. phytoseiuli, M. phytoseiuli and O. occidentalis) an infection may be connected with fitness costs of the host. Moreover, infection is not always readily visible as no obvious gross symptoms are present. Monitoring of these entities on a routine and continuous basis should therefore get more attention, especially in commercial mass-production. Special attention should be paid to field-collected mites before introduction into the laboratory or mass rearing, and to mites that are exchanged among rearing facilities. However, at present general pathogen monitoring is not yet practical as effects of many entities are unknown. More research effort is needed concerning verified and potential pathogens of commercially reared arthropods and those used as model organisms in research

    Molecular identification of adenoviruses associated with respiratory infection in Egypt from 2003 to 2010.

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    BACKGROUND: Human adenoviruses of species B, C, and E (HAdV-B, -C, -E) are frequent causative agents of acute respiratory infections worldwide. As part of a surveillance program aimed at identifying the etiology of influenza-like illness (ILI) in Egypt, we characterized 105 adenovirus isolates from clinical samples collected between 2003 and 2010. METHODS: Identification of the isolates as HAdV was accomplished by an immunofluorescence assay (IFA) and confirmed by a set of species and type specific polymerase chain reactions (PCR). RESULTS: Of the 105 isolates, 42% were identified as belonging to HAdV-B, 60% as HAdV-C, and 1% as HAdV-E. We identified a total of six co-infections by PCR, of which five were HAdV-B/HAdV-C co-infections, and one was a co-infection of two HAdV-C types: HAdV-5/HAdV-6. Molecular typing by PCR enabled the identification of eight genotypes of human adenoviruses; HAdV-3 (n = 22), HAdV-7 (n = 14), HAdV-11 (n = 8), HAdV-1 (n = 22), HAdV-2 (20), HAdV-5 (n = 15), HAdV-6 (n = 3) and HAdV-4 (n = 1). The most abundant species in the characterized collection of isolates was HAdV-C, which is concordant with existing data for worldwide epidemiology of HAdV respiratory infections. CONCLUSIONS: We identified three species, HAdV-B, -C and -E, among patients with ILI over the course of 7 years in Egypt, with at least eight diverse types circulating

    A transcription factor contributes to pathogenesis and virulence in streptococcus pneumoniae

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    To date, the role of transcription factors (TFs) in the progression of disease for many pathogens is yet to be studied in detail. This is probably due to transient, and generally low expression levels of TFs, which are the central components controlling the expression of many genes during the course of infection. However, a small change in the expression or specificity of a TF can radically alter gene expression. In this study, we combined a number of quality-based selection strategies including structural prediction of modulated genes, gene ontology and network analysis, to predict the regulatory mechanisms underlying pathogenesis of Streptococcus pneumoniae (the pneumococcus). We have identified two TFs (SP_0676 and SP_0927 [SmrC]) that might control tissue-specific gene expression during pneumococcal translocation from the nasopharynx to lungs, to blood and then to brain of mice. Targeted mutagenesis and mouse models of infection confirmed the role of SP_0927 in pathogenesis and virulence, and suggests that SP_0676 might be essential to pneumococcal viability. These findings provide fundamental new insights into virulence gene expression and regulation during pathogenesis.Layla K. Mahdi, Esmaeil Ebrahimie, David L. Adelson, James C. Paton, Abiodun D. Ogunniy

    Efficacy of Single-Dose and Triple-Dose Albendazole and Mebendazole against Soil-Transmitted Helminths and Taenia spp.: A Randomized Controlled Trial

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    BACKGROUND: The control of soil-transmitted helminth (STH) infections currently relies on the large-scale administration of single-dose oral albendazole or mebendazole. However, these treatment regimens have limited efficacy against hookworm and Trichuris trichiura in terms of cure rates (CR), whereas fecal egg reduction rates (ERR) are generally high for all common STH species. We compared the efficacy of single-dose versus triple-dose treatment against hookworm and other STHs in a community-based randomized controlled trial in the People's Republic of China. METHODOLOGY/PRINCIPAL FINDINGS: The hookworm CR and fecal ERR were assessed in 314 individuals aged </=5 years who submitted two stool samples before and 3-4 weeks after administration of single-dose oral albendazole (400 mg) or mebendazole (500 mg) or triple-dose albendazole (3x400 mg over 3 consecutive days) or mebendazole (3x500 mg over 3 consecutive days). Efficacy against T. trichiura, Ascaris lumbricoides, and Taenia spp. was also assessed. ALBENDAZOLE CURED SIGNIFICANTLY MORE HOOKWORM INFECTIONS THAN MEBENDAZOLE IN BOTH TREATMENT REGIMENS (SINGLE DOSE: respective CRs 69% (95% confidence interval [CI]: 55-81%) and 29% (95% CI: 20-45%); triple dose: respective CRs 92% (95% CI: 81-98%) and 54% (95% CI: 46-71%)). ERRs followed the same pattern (single dose: 97% versus 84%; triple dose: 99.7% versus 96%). Triple-dose regimens outperformed single doses against T. trichiura; three doses of mebendazole - the most efficacious treatment tested - cured 71% (95% CI: 57-82%). Both single and triple doses of either drug were highly efficacious against A. lumbricoides (CR: 93-97%; ERR: all <99.9%). Triple dose regimens cured all Taenia spp. infections, whereas single dose applications cured only half of them. CONCLUSIONS/SIGNIFICANCE: Single-dose oral albendazole is more efficacious against hookworm than mebendazole. To achieve high CRs against both hookworm and T. trichiura, triple-dose regimens are warranted. CONCLUSIONS/SIGNIFICANCE: Single-dose oral albendazole is more efficacious against hookworm than mebendazole. To achieve high CRs against both hookworm and T. trichiura, triple-dose regimens are warranted. TRIAL REGISTRATION: www.controlled-trials.comISRCTN4737502

    Factors influencing citrus fruit scarring caused by Pezothrips kellyanus

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    [EN] Kelly s citrus thrips (KCT) Pezothrips kellyanus (Bagnall) (Thysanoptera: Thripidae) is a recently recorded cosmopolitan citrus pest, causing fruit scarring that results in downgrading of fruit. Due to the detrimental effects caused on fruits by KCT, we wanted to study some of the factors influencing fruit scarring. Specifically, the objectives were: (1) to determine the fruit development stage when citrus fruits are damaged by KCT and the population structure of KCT during this period, (2) to study the influence of temperature on intensity of damage, and finally, (3) to identify alternative host plants. KCT populations on flowers and fruitlets and alternate plant hosts were sampled in four citrus orchards from 2008 to 2010. The percentage of damaged fruits was also recorded. The exotic vine Araujia sericifera (Apocynaceae) was recorded as a new host for KCT. Thrips scarring started to increase at 350 650 degree-days (DD) above 10.2 C, coinciding with a peak abundance of the second instar larval stages over all 3 years of the study. The maximum percentage of larval stages of KCT was observed in the 3 years at about 500 DD, a period which corresponds to the end of May or early June. Variation in the severity of fruit scarring appeared to be related to air temperature. Temperature likely affects the synchronisation between the peak in abundance of KCT larvae, and the period when fruitlets are susceptible to thrips damage. Temperature can also influence the survival and development of KCT populations in citrus and other host plants in the citrus agro-ecosystem.The authors thank Alejandro Tena for his valuable suggestions and two anonymous referees for their careful review and helpful comments. We also extend our thanks to the owners of the commercial orchards for giving us permission to use their citrus orchards. 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