Silicon Thin Films:Functional Materials for Energy, Healthcare, and IT Applications

The authors review selected topics in the development of hydrogenated amorphous silicon (a‐Si:H), from its emergence some 50 years ago to its present status as a mature thin‐film semiconductor, with market successes including flat‐panel displays, solar modules, and x‐ray scanners. By altering process gas mixtures and deposition conditions, films with a range of atomic, structural, and amorphous/crystalline phase compositions may be deposited, offering tunable bandgap, refractive index, and light‐scattering properties. Films thus “functionalized” have greatly increased scope and utility. Three emerging applications are reported, and more extensive sections on two topics of current importance are presented: 1) Multi‐junction thin film silicon solar cells for water splitting applications; and 2) thin‐film silicon solar cells on flexible substrates

In renal cell carcinoma the PTEN splice variant PTEN-Δ shows similar function as the tumor suppressor PTEN itself

BACKGROUND: Loss of PTEN is involved in tumor progression of several tumor entities including renal cell carcinoma (RCC). During the translation process PTEN generates a number of splice variants, including PTEN-Δ. We analyzed the impact of PTEN-Δ in RCC progression. METHODS: In specimens of RCC patients the expression of PTEN-Δ and PTEN was quantified. The PTEN expressing RCC cell line A498 and the PTEN deficient 786-O cell line were stably transfected with the PTEN-Δ or PTEN transcript. In Caki-1 cells that highly express PTEN-Δ, this isoform was knocked down by siRNA. Cell migration, adhesion, apoptosis and signaling pathways activities were consequently analyzed in vitro. RESULTS: Patients with a higher PTEN-Δ expression had a longer lymph node metastasis free and overall survival. In RCC specimens, the PTEN-Δ expression correlated with the PTEN expression. PTEN-Δ as well as PTEN induced a reduced migration when using extracellular matrix (ECM) compounds as chemotaxins. This effect was confirmed by knockdown of PTEN-Δ, inducing an enhanced migration. Likewise a decreased adhesion on these ECM components could be shown in PTEN-Δ and PTEN transfected cells. The apoptosis rate was slightly increased by PTEN-Δ. In a phospho-kinase array and Western blot analyses a consequently reduced activity of AKT, p38 and JNK could be shown. CONCLUSIONS: We could show that the PTEN splice variant PTEN-Δ acts similar to PTEN in a tumor suppressive manner, suggesting synergistic effects of the two isoforms. The impact of PTEN-Δ in context of tumor progression should thus be taken into account when generating new therapeutic options targeting PTEN signaling in RCC

Identification of 12 new susceptibility loci for different histotypes of epithelial ovarian cancer.

To identify common alleles associated with different histotypes of epithelial ovarian cancer (EOC), we pooled data from multiple genome-wide genotyping projects totaling 25,509 EOC cases and 40,941 controls. We identified nine new susceptibility loci for different EOC histotypes: six for serous EOC histotypes (3q28, 4q32.3, 8q21.11, 10q24.33, 18q11.2 and 22q12.1), two for mucinous EOC (3q22.3 and 9q31.1) and one for endometrioid EOC (5q12.3). We then performed meta-analysis on the results for high-grade serous ovarian cancer with the results from analysis of 31,448 BRCA1 and BRCA2 mutation carriers, including 3,887 mutation carriers with EOC. This identified three additional susceptibility loci at 2q13, 8q24.1 and 12q24.31. Integrated analyses of genes and regulatory biofeatures at each locus predicted candidate susceptibility genes, including OBFC1, a new candidate susceptibility gene for low-grade and borderline serous EOC

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Solar driven water electrolysis based on silicon solar cells and earth-abundant catalysts

In the present work “proof of concept” upscaling steps were taken for a PV-EC device of 100 cm² substrate size. The active thin film silicon solar cell area was increased to 64 cm², while earth-abundant nickel based catalysts were scaled up by a factor of 100 to electrode areas of 50.3 cm². Implementing the thin film silicon solar cell into the PV-EC device in combination with the earth-abundant catalysts yielded a solar-to-hydrogen efficiency of 5.1 %, which is significantly improved compared to a PV-EC device based on nickel electrodes. It is shown that noble metal catalysts can be replaced by earth-abundant materials without performance losses. The long-term stable operation of the scaled up PV-EC devices is ensured by the use of metal sheet electrodes serving as substrate for the catalyst deposition. Regarding the catalyst stability, an excellent performance over 4 days under day-night-cycling was found for the earth-abundant nickel based system. Furthermore, the characterization of integrated PV-EC devices was expanded to illumination conditions similar to those obtained outdoors. All components used in water splitting devices are usually optimized under standard test conditions in the laboratory, which only represent one set of a wide range of possible outdoor operating conditions. For a combined PV-EC system the generation of hydrogen will only occur for output voltages above a certain value (thermodynamic potential + overpotential losses). This means, any illumination conditions shifting the illuminated current-voltage curve of the coupled system such that the voltage at the operating point is too low, will switch the system off. The influence of the operating temperature has been investigated prior to the present work, but studies concerning other possible illumination conditions were missing and therefore investigated in the present work. Additionally, a first estimation of the annual hydrogen output is given to compare devices based on different multi-junction cells and employing different catalyst systems for spectral data reported in literature

Solar driven water electrolysis based on silicon solar cells and earth-abundant catalysts

In the present work “proof of concept” upscaling steps were taken for a PV-EC device of 100 cm$^{2}$ substrate size. The active thin film silicon solar cell area was increased to 64 cm$^{2}$, while earth-abundant nickel based catalysts were scaled up by a factor of 100 to electrode areas of 50.3 cm$^{2}$. Implementing the thin film siliconsolar cell into the PV-EC device in combination with the earth-abundant catalysts yielded a solar-to-hydrogen efficiency of 5.1 %, which is significantly improved compared to a PV-EC device based on nickel electrodes. It is shown that noble metal catalysts can be replaced by earth-abundant materials without performance losses. The long-term stable operation of the scaled up PV-EC devices is ensured by the use of metal sheet electrodes serving as substrate for the catalyst deposition. Regarding the catalyst stability, an excellent performance over 4 days under day-night-cycling was found for the earth-abundant nickel based system. Furthermore, the characterization of integrated PV-EC devices was expanded to illumination conditions similar to those obtained outdoors. All components used in water splitting devices are usually optimized under standard test conditions in the laboratory, which only represent one set of a wide range of possible outdoor operating conditions. For a combined PV-EC system the generation of hydrogen will only occur for output voltages above a certain value (thermodynamic potential + overpotential losses). This means, any illumination conditions shifting the illuminated current-voltage curve of the coupled system such that the voltage at the operating point is too low, will switch the system off. The influence of the operating temperature has been investigated prior to the present work, but studies concerning other possible illumination conditions were missing and therefore investigated in the present work. Additionally, a first estimation of the annual hydrogen output is given to compare devices based on different multi-junction cells and employing different catalyst systems for spectral data reported in literature