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Deepthi B.,National Aerospace Laboratories, Bangalore | Srinivas G.,National Aerospace Laboratories, Bangalore | Kumar P.,National Aerospace Laboratories, Bangalore | Sridhara Rao D.V.,Electronic Microscopy Group | Barshilia H.C.,National Aerospace Laboratories, Bangalore
Nanoscience and Nanotechnology Letters | Year: 2012

Au-WS 2 nanocomposite coatings with approximately 60 at.% Au were prepared using magnetron sputtering from high purity Au and WS 2 targets. Structural characterization of the coatings using X-ray diffraction indicated the presence of (111), (200) and (220) peaks of cubic Au and broad bands corresponding to (002) and (004) planes of hexagonal WS 2. Surface morphology of Au-WS 2 coatings was studied using field emission scanning electron microscopy (FESEM) and atomic force microscopy which showed formation of uniformly distributed interconnected ligament-like features. High resolution transmission electron microscopy studies showed the presence of a two phase nanocomposite structure wherein nanocrystalline Au was dispersed in a matrix of nanocrystalline and amorphous WS 2. The electrical resistivity of Au-WS 2 coating measured using four-point-probe method was approximately 0.2 μω m compared to Au and WS 2 coatings which exhibited electrical resistivity values of approximately 0.04.m and 0.057 μωm, respectively. Ball-on-disc reciprocating tests at a load of 7 N showed that Au-WS 2 nanocomposite coating exhibited a friction coefficient of 0.22 after 57,600 cycles and outperformed Au and WS 2 coatings. Analyses of the ball and wear track of Au-WS 2 coating using FESEM at the end of the wear test indicated formation of smooth transfer films, less accumulation of wear debris and reduced oxidation. Copyright © 2012 American Scientific Publishers. All rights reserved.

De Boer A.D.,University of Gottingen | De Groot P.W.J.,University of Amsterdam | De Groot P.W.J.,University of Castilla - La Mancha | Weindl G.,University of Tubingen | And 10 more authors.
Yeast | Year: 2010

The glycosylphosphatidylinositol-modified protein Rhd3/Pga29 of the human pathogen Candida albicans belongs to a family of cell wall proteins that are widespread among Candida species but are not found in other fungi. Pga29 is covalently linked to the β-1,3-glucan framework of the cell wall via β-1,6-glucan. It is a small and abundant O-glycosylated protein and requires the protein-O-mannosyl transferase Pmt1 for glycosylation. Furthermore, Pga29 is strongly expressed in yeast cells but is downregulated in hyphae. Removal of the PGA29 gene in C. albicans leads to a significant reduction of cell wall mannan; however, Pga29 does not seem to have a major role in maintaining cell wall integrity. In addition, adhesion capacity and hyphae formation appear normal in pga29 deletion mutants. Importantly, the pga29 deletion mutant is less virulent, and infection of reconstituted human epithelium with the pga29 mutant results in a diminished induction of proinflammatory cytokines, such as GM-CSF, TNF, IL-6 and IL-8. We propose that the reduced virulence of the pga29 mutant is a consequence of altered surface properties, resulting in altered fungal recognition. Copyright © 2010 John Wiley & Sons, Ltd.

Edgcombe C.J.,TFM Group | Ionescu A.,TFM Group | Loudon J.C.,Electronic Microscopy Group | Blackburn A.M.,Hitachi Cambridge Laboratory | And 2 more authors.
Ultramicroscopy | Year: 2012

Holographic measurements on magnetised thin-film cobalt rings have demonstrated both onion and vortex states of magnetisation. For a ring in the vortex state, the difference between phases of electron paths that pass through the ring and those that travel outside it was found to agree very well with Aharonov-Bohm theory within measurement error. Thus the magnetic flux in thin-film rings of ferromagnetic material can provide the phase shift required for phase plates in transmission electron microscopy. When a ring of this type is used as a phase plate, scattered electrons will be intercepted over a radial range similar to the ring width. A cobalt ring of thickness 20. nm can produce a phase difference of π/2 from a width of just under 30. nm, suggesting that the range of radial interception for this type of phase plate can be correspondingly small. © 2012 Elsevier B.V.

Pramanik P.,University of Calcutta | Sen S.,University of Calcutta | Singha C.,University of Calcutta | Roy A.S.,University of Calcutta | And 3 more authors.
IEEE Journal of Quantum Electronics | Year: 2016

The detection of a specific spectral line in ultraviolet in the presence of broadband ambient lighting is necessary for many applications. We report wavelength-selective photodetection using AlGaN multiple quantum wells grown by molecular beam epitaxy. A near-Gaussian photoresponse peak at 300 nm with a width of 17 nm was achieved in the lateral photocurrent, along with a much faster transient response compared with the devices based on bulk AlGaN. The wavelength selectivity, controlled by the formation and subsequent splitting of excitons, was achieved by the optimization of the alloy properties of the barrier layers, reducing the leakage of photogenerated carriers into the active region. © 1965-2012 IEEE.

Studencka M.,Max Planck Institute for Biophysical Chemistry | Konzer A.,Max Planck Institute for Heart and Lung Research | Moneron G.,Max Planck Institute for Biophysical Chemistry | Wenzel D.,Electronic Microscopy Group | And 10 more authors.
Molecular and Cellular Biology | Year: 2012

Linker histone (H1) and heterochromatin protein 1 (HP1) are essential components of heterochromatin which contribute to the transcriptional repression of genes. It has been shown that the methylation mark of vertebrate histone H1 is specifically recognized by the chromodomain of HP1. However, the exact biological role of linker histone binding to HP1 has not been determined. Here, we investigate the function of the Caenorhabditis elegans H1 variant HIS-24 and the HP1-like proteins HPL-1 and HPL-2 in the cooperative transcriptional regulation of immune-relevant genes. We provide the first evidence that HPL-1 interacts with HIS-24 monomethylated at lysine 14 (HIS-24K14me1) and associates in vivo with promoters of genes involved in antimicrobial response. We also report an increase in overall cellular levels and alterations in the distribution of HIS-24K14me1 after infection with pathogenic bacteria. HIS-24K14me1 localization changes from being mostly nuclear to both nuclear and cytoplasmic in the intestinal cells of infected animals. Our results highlight an antimicrobial role of HIS-24K14me1 and suggest a functional link between epigenetic regulation by an HP1/H1 complex and the innate immune system in C. elegans. © 2012, American Society for Microbiology.

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