Photoresponse from noble metal nanoparticles-multi walled carbon nanotube composites

In this Letter, we investigated the photo-response of multi wall carbon nanotube-based composites obtained from in situ thermal evaporation of noble metals (Au, Ag, and Cu) on the nanotube films. The metal deposition process produced discrete nanoparticles on the nanotube outer walls. The nanoparticle-carbon nanotube films were characterized by photo-electrochemical measurements in a standard three electrode cell. The photocurrent from the decorated carbon nanotubes remarkably increased with respect to that of bare multiwall tubes. With the aid of first-principle calculations, these results are discussed in terms of metal nanoparticle–nanotube interactions and electronic charge transfer at the interface.VC 2012 American Institute of Physics

Phosphatidylinositol phosphate kinase type Iγ regulates dynamics of large dense-core vesicle fusion.

Phosphatidylinositol-4,5-bisphosphate was proposed to be an important regulator of large dense-core vesicle exocytosis from neuroendocrine tissues. Here, we have examined the kinetics of secretion in chromaffin cells from mice lacking phosphatidylinositol phosphate kinase type Iγ, the major neuronal phosphatidylinositol-4-phosphate 5-kinase. Absence of this enzyme caused a reduction of the readily releasable vesicle pool and its refilling rate, with a small increase in morphologically docked vesicles, indicating a defect in vesicle priming. Furthermore, amperometry revealed a delay in fusion pore expansion. These results provide direct genetic evidence for a key role of phosphatidylinositol-4,5-bisphosphate synthesis in the regulation of large dense-core vesicle fusion dynamics

Endophilins interact with Moloney murine leukemia virus Gag and modulate virion production

BACKGROUND: The retroviral Gag protein is the central player in the process of virion assembly at the plasma membrane, and is sufficient to induce the formation and release of virus-like particles. Recent evidence suggests that Gag may co-opt the host cell's endocytic machinery to facilitate retroviral assembly and release. RESULTS: A search for novel partners interacting with the Gag protein of the Moloney murine leukemia virus (Mo-MuLV) via the yeast two-hybrid protein-protein interaction assay resulted in the identification of endophilin 2, a component of the machinery involved in clathrin-mediated endocytosis. We demonstrate that endophilin interacts with the matrix or MA domain of the Gag protein of Mo-MuLV, but not of human immunodeficiency virus, HIV. Both exogenously expressed and endogenous endophilin are incorporated into Mo-MuLV viral particles. Titration experiments suggest that the binding sites for inclusion of endophilin into viral particles are limited and saturable. Knock-down of endophilin with small interfering RNA (siRNA) had no effect on virion production, but overexpression of endophilin and, to a lesser extent, of several fragments of the protein, result in inhibition of Mo-MuLV virion production, but not of HIV virion production. CONCLUSIONS: This study shows that endophilins interact with Mo-MuLV Gag and affect virion production. The findings imply that endophilin is another component of the large complex that is hijacked by retroviruses to promote virion production

A role of OCRL in clathrin-coated pit dynamics and uncoating revealed by studies of Lowe syndrome cells

Mutations in the inositol 5-phosphatase OCRL cause Lowe syndrome and Dent's disease. Although OCRL, a direct clathrin interactor, is recruited to late-stage clathrin-coated pits, clinical manifestations have been primarily attributed to intracellular sorting defects. Here we show that OCRL loss in Lowe syndrome patient fibroblasts impacts clathrin-mediated endocytosis and results in an endocytic defect. These cells exhibit an accumulation of clathrin-coated vesicles and an increase in U-shaped clathrin-coated pits, which may result from sequestration of coat components on uncoated vesicles. Endocytic vesicles that fail to lose their coat nucleate the majority of the numerous actin comets present in patient cells. SNX9, an adaptor that couples late-stage endocytic coated pits to actin polymerization and which we found to bind OCRL directly, remains associated with such vesicles. These results indicate that OCRL acts as an uncoating factor and that defects in clathrin-mediated endocytosis likely contribute to pathology in patients with OCRL mutations

Tracking interfacial changes of graphene/Ge(110) during in-vacuum annealing

Graphene quality indicators obtained by Raman spectroscopy have been correlated to the structural changes of the graphene/Germanium interface as a function of in-vacuum thermal annealing. Specifically, it is found that graphene becomes markedly defected at 650 {\deg}C. By combining scanning tunneling microscopy, x-Ray Photoelectron Spectroscopy and Near Edge x-ray Absorption Fine Structure Spectroscopy, we conclude that these defects are due to the release of H_{2} gas trapped at the graphene/Germanium interface. The H_{2} gas was produced following the transition from the as-grown hydrogen-termination of the Ge(110) surface to the emergence of surface reconstructions in the substrate. Interestingly, a complete self-healing process is observed in graphene upon annealing to 800 {\deg}C. The subtle interplay revealed between the microscopic changes occurring at the graphene/Germanium interface and graphene's defect density is valuable for advancing graphene growth, controlled 2D-3D heterogeneous materials interfacing and integrated fabrication technology on semiconductors

an integrated low cost road traffic and air pollution monitoring platform to assess vehicles air quality impact in urban areas

Abstract An integrated monitoring platform (IMP) was developed for real-time monitoring of traffic flows and related air pollution in urban areas. The IMP includes: (i) an air quality monitoring unit, integrating the "Arduino" open-source technology with low-cost and high-resolution sensors, to measure air pollutant concentrations; (ii) a traffic monitoring device, equipped with a camera sensor and a video analysis software, to detect vehicles' counts, speed and category; (iii) a spatial data infrastructure, composed of a central GeoDatabase, a GIS engine, and a web interface, for data storage and management. The IMP was tested in Florence (Italy) by installing sensor devices at a road site where a 1-year measuring campaign was carried out. A reference meteorological station in the city centre was used to provide observations of wind speed and direction, air temperature, and relative humidity. In this work, a statistical analysis was performed to investigate the influence of local road traffic and meteorological conditions on CO, NO2 and CO2 concentrations. Two different methods were applied: a linear regression model and an artificial neural network. To investigate the role played by emissions from road traffic, the influence of all drivers by period of the year (cold vs. warm months) and day of the week (weekdays vs. weekends) was analysed. As a result, the contribution of local road traffic on pollutant concentrations proved to be lower than meteorological parameters