17 research outputs found
Chemical, Structural and Optical Properties of ē-Beam Evaporated Tungsten Diselenide Polycrystalline Thin Film
Polycrystalline thin films of tungsten dieseline were prepared by using rarely reported technique of electron beam evaporation for transition metal dichalcogenides. High purity (99.999 %) reacted compound was used as starting material for the preparation of WSe2 thin films. Various parameters and conditions are outlined which were used for deposition of thin films. The prepared films were characterized using EDAX spectrum, X-ray diffraction, Electron diffraction, Scanning electron microscopy and optical absorption spectroscopy methods. The as grown films were found to be partially transparent, uniform and well adherent. Uniformity was confirmed by SEM. WSe2 film was found in stoichiometric proportion. XRD pattern as well as TEM images revealed the fact that the deposited films are polycrystalline in nature having hexagonal structure. From the study of optical absorption spectra it is found that the prepared films show direct allowed transition with optical band gap of 1.89 eV. The results are in good agreement with the earlier published data of WSe2 thin films deposited by different techniques.
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Mechanisms of viral entry: sneaking in the front door
Recent developments in methods to study virus internalisation are providing clearer insights into mechanisms used by viruses to enter host cells. The use of dominant negative constructs, specific inhibitory drugs and RNAi to selectively prevent entry through particular pathways has provided evidence for the clathrin-mediated entry of hepatitis C virus (HCV) as well as the caveolar entry of Simian Virus 40. Moreover, the ability to image and track fluorescent-labelled virus particles in real-time has begun to challenge the classical plasma membrane entry mechanisms described for poliovirus and human immunodeficiency virus. This review will cover both well-documented entry mechanisms as well as more recent discoveries in the entry pathways of enveloped and non-enveloped viruses. This will include viruses which enter the cytosol directly at the plasma membrane and those which enter via endocytosis and traversal of internal membrane barrier(s). Recent developments in imaging and inhibition of entry pathways have provided insights into the ill-defined entry mechanism of HCV, bringing it to the forefront of viral entry research. Finally, as high-affinity receptors often define viral internalisation pathways, and tropism in vivo, host membrane proteins to which viral particles specifically bind will be discussed throughout
Towards reconciling structure and function in the nuclear pore complex
The spatial separation between the cytoplasm and the cell nucleus necessitates the continuous exchange of macromolecular cargo across the double-membraned nuclear envelope. Being the only passageway in and out of the nucleus, the nuclear pore complex (NPC) has the principal function of regulating the high throughput of nucleocytoplasmic transport in a highly selective manner so as to maintain cellular order and function. Here, we present a retrospective review of the evidence that has led to the current understanding of both NPC structure and function. Looking towards the future, we contemplate on how various outstanding effects and nanoscopic characteristics ought to be addressed, with the goal of reconciling structure and function into a single unified picture of the NPC