Plasmonic Enhancement of Dye Sensitized Solar Cells via a Tailored Size-Distribution of Chemically Functionalized Gold Nanoparticles

A substantial and stable increase of the current density J_sc of ruthenium (Ru) dye sensitized solar cells (DSC) of up to 16.18% and of the power efficiency of up to 25.5% is demonstrated in this article via plasmonic enhancement. The key aspect of this work is the use of a tailored bimodal size distribution of functionalized gold nanoparticles (AuNPs) that have been chemically immobilized onto the mesoporous titanium dioxide (TiO₂) layer via short, stable dithiodibutyric acid linkers. The size distribution of the AuNPs is a result of theoretical calculations that aimed at the perfection of the absorption characteristics of the complete solar cell system over a wide range of wavelengths. The functionalization of the AuNPs serves to bind them at a close but defined distance to TiO₂-particles and additionally to chemically protect them against potential corrosion by the electrolyte. Simulations of near field (enhanced absorption) and far field (scattering) contributions have been used to tailor a complex AuNPs bimodal size distribution that had subsequently demonstrated experimentally a close to optimum improvement of the absorbance over a wide wavelength range (500–675 nm) and therefore an impressive DSC efficiency enhancement. Finally, the modified DSCs are exhibiting pronounced longevity and stable performance as confirmed via long time measurements. In summary, the presented systems show increased performance compared to non plasmonic enhanced cells with otherwise identical composition, and are demonstrating a previously unpublished longevity for iodide electrolyte/AuNPs combinations.     

Population genomics of the pathogenic yeast Candida tropicalis identifies hybrid isolates in environmental samples

Candida tropicalis is a human pathogen that primarily infects the immunocompromised. Whereas the genome of one isolate, C. tropicalis MYA-3404, was originally sequenced in 2009, there have been no large-scale, multi-isolate studies of the genetic and phenotypic diversity of this species. Here, we used whole genome sequencing and phenotyping to characterize 77 isolates of C. tropicalis from clinical and environmental sources from a variety of locations. We show that most C. tropicalis isolates are diploids with approximately 2–6 heterozygous variants per kilobase. The genomes are relatively stable, with few aneuploidies. However, we identified one highly homozygous isolate and six isolates of C. tropicalis with much higher heterozygosity levels ranging from 36–49 heterozygous variants per kilobase. Our analyses show that the heterozygous isolates represent two different hybrid lineages, where the hybrids share one parent (A) with most other C. tropicalis isolates, but the second parent (B or C) differs by at least 4% at the genome level. Four of the sequenced isolates descend from an AB hybridization, and two from an AC hybridization. The hybrids are MTLa/α heterozygotes. Hybridization, or mating, between different parents is therefore common in the evolutionary history of C. tropicalis. The new hybrids were predominantly found in environmental niches, including from soil. Hybridization is therefore unlikely to be associated with virulence. In addition, we used genotype-phenotype correlation and CRISPR-Cas9 editing to identify a genome variant that results in the inability of one isolate to utilize certain branched-chain amino acids as a sole nitrogen source.     

Evaluation of the National Notifiable Diseases Surveillance System for Dengue Fever in Taiwan, 2010–2012

BackgroundIn Taiwan, around 1,500 cases of dengue fever are reported annually and incidence has been increasing over time. A national web-based Notifiable Diseases Surveillance System (NDSS) has been in operation since 1997 to monitor incidence and trends and support case and outbreak management. We present the findings of an evaluation of the NDSS to ascertain the extent to which dengue fever surveillance objectives are being achieved.MethodologyWe extracted the NDSS data on all laboratory-confirmed dengue fever cases reported during 1 January 2010 to 31 December 2012 to assess and describe key system attributes based on the Centers for Disease Control and Prevention surveillance evaluation guidelines. The system’s structure and processes were delineated and operational staff interviewed using a semi-structured questionnaire. Crude and age-adjusted incidence rates were calculated and key demographic variables were summarised to describe reporting activity. Data completeness and validity were described across several variables.Conclusions/SignificanceThe NDSS for dengue fever surveillance is a robust, well maintained and acceptable system that supports the collection of complete and valid data needed to achieve the surveillance objectives. The simplicity of the system engenders compliance leading to timely and accurate reporting. Completeness of hospitalization information could be further improved to allow assessment of severity of illness. To minimize misclassification, an algorithm to accurately classify travel cases should be established.     

An Outbreak of Cryptosporidium parvum across England & Scotland Associated with Consumption of Fresh Pre-Cut Salad Leaves,May 2012

BackgroundWe report a widespread foodborne outbreak of Cryptosporidium parvum in England and Scotland in May 2012. Cases were more common in female adults, and had no history of foreign travel. Over 300 excess cases were identified during the period of the outbreak. Speciation and microbiological typing revealed the outbreak strain to be C. parvum gp60 subtype IIaA15G2R1.MethodsHypothesis generation questionnaires were administered and an unmatched case control study was undertaken to test the hypotheses raised. Cases and controls were interviewed by telephone. Controls were selected using sequential digit dialling. Information was gathered on demographics, foods consumed and retailers where foods were purchased.ResultsSeventy-four laboratory confirmed cases and 74 controls were included in analyses. Infection was found to be strongly associated with the consumption of pre-cut mixed salad leaves sold by a single retailer. This is the largest documented outbreak of cryptosporidiosis attributed to a food vehicle.     

Use of the comet-FISH assay to demonstrate repair of the TP53 gene region in two human bladder carcinoma cell lines

The alkaline single-cell gel electrophoresis (comet) assay can be combined with fluorescence in situ hybridization (FISH) methodology to investigate the localization of specific gene domains within an individual cell. The position of the fluorescent hybridization spots in the comet head or tail indicates whether the sequence of interest lies within or in the vicinity of a damaged region of DNA. In this study, we used the comet-FISH assay to examine initial DNA damage and subsequent repair in the TP53 gene region of RT4 and RT112 bladder carcinoma cells after 5 Gy gamma irradiation. In addition to standard comet parameter measurements, the number and location of TP53 hybridization spots within each comet was recorded at each repair time. The results indicate that the rate of repair of the TP53 gene region was fastest during the first 15 min after damage in both cell lines. When compared to overall genomic repair, the repair of the TP53 gene region was observed to be significantly faster during the first 15 min and thereafter followed a rate similar to that for the overall genome. The data indicate that the TP53 domain in RT4 and RT112 cells is repaired rapidly after gamma irradiation. Furthermore, this repair may be preferential compared to the repair of overall genomic DNA, which gives a measure of the average DNA repair response of the whole genome. We suggest that the comet-FISH assay has considerable potential in the study of gene-specific repair after DNA damage.     

Nanoimprint Lithography–Based Fabrication of Plasmonic Array of Elliptical Nanoholes for Dual-Wavelength,Dual-Polarisation Refractive Index Sensing

Plasmonics - We report on the novel fabrication and characterisation of plasmonic arrays of elliptical nanohole, and their use for refractive index based sensing. The substrates were fabricated...     

Using photoelectron elliptical dichroism (PEELD) to determine real-time variation of enantiomeric excess

In this work, the photoionization of chiral molecules by an elliptically polarized, high repetition rate, femtosecond laser is probed. The resulting 3D photoelectron angular distribution shows a strong forward–backward asymmetry, which is highly dependent not only on the molecular structure but also on the ellipticity of the laser pulse. By continuously varying the laser ellipticity, we can observe molecular and enantiomer changes in real time at a previously unseen speed and precision. The technique allows enantiomeric excess of a pure compound to be measured with a 5% precision within 3 s, and a 10-min acquisition yields a precision of 0.4%. The isomers camphor and fenchone can be easily distinguished, unlike with conventional mass spectrometry. Preliminary results for the pharmaceutically interesting ibuprofen are also given, showing the capability of photoionization as a means of distinguishing larger molecular systems.     

Macrophages and Apoptotic cells in Human Colorectal Tumours

The numerical relationship between tumour associated macrophages (TAM) and apoptotic cells in 12 human colorectal tumours was evaluated. TAM were labelled immunohistochemically and apoptotic cells were visualized by counterstaining with haematoxylin and eosin (H&E). The stereological techniques. Cavalieri's estimator of volume and the Disector were used to estimate both tumour volume and numerical density of both cell types. The occurrence of TAM per unit volume of tissue increased with increasing tumour volume to a maximum in a tumour of 110·5 cm³, after which numbers declined. Levels of apoptosis also increased with tumour volume though more erratically than levels of TAM and declined for tumour volumes greater than 80 cm³. This is the first report of an attempt to assess the relationship between apoptotic cells and TAM in human tumours.