Roma Chauhan

Synthesis and characterization of ZnO thin film grown by electron beam evaporation

Highly transparent, conducting, highly oriented, and almost single phase ZnO films have been deposited by simple e-beam evaporation method, and the deposition parameters were optimized. The films were prepared by (a) evaporation of ZnO at different substrate temperatures and (b) evaporation of ZnO at room temperature and subsequent annealing of the films in oxygen ambient at different temperatures. The characterizations of the film were performed by optical absorption spectroscopy (UV-visible), Fourier transform infrared spectroscopy, resistivity measurement, transmission electron microscopy (TEM), photoluminescence, and x-ray diffraction measurement. Absorption spectra revealed that the films were highly transparent and the band gap of the pre- and postannealed films was in good agreement with the reported values. The band gap of the films increases on increasing the substrate temperature as well as annealing temperature, whereas the resistivity of the film decreases with substrate temperature and increa...

Newcastle disease virus-induced cytopathic effect in infected cells is caused by apoptosis.

The velogenic Newcastle disease virus (NDV) causes highly infectious and economically significant Newcastle disease (ND) in birds of various species. In cell culture NDV induces cytopathic effect (CPE) characterized by rounding, vacuolation, syncytia formation and cell death. Aside from cell to cell fusion caused by the F and HN glycoprotein of the virus molecular events leading to cell death are not known. In the current study, NDV-infected Vero cells, at 48 h p.i., showed nuclear condensation, cytoplasm blebbing, DNA fragmentation, and phosphatidylserine translocation to the cell surface. In addition, virus-infected cells demonstrated decreased DNA content and an increased Bax to Bcl-2 ratio, p53 level and caspase 3, 8, 9 expression compared to mock-infected cells. Based on these results, it was concluded that CPE in NDV-infected cells was caused by to the induction of apoptosis with the involvement of p53 and the Bax, dependent apoptotic pathways.

Formation of self-affine nanostructures on ZnO surfaces by swift heavy ions

The topography evolution using the high energy heavy ion irradiation revealed the fact that ion bombardment produces self-affine nanostructures, creating peculiar surface morphologies and regular structures on the surface of the ZnO thin film at certain fluences. The self-affine nanopatterns produced on the surface of ZnO thin film under swift heavy ion irradiation are different types of nanostructures such as nanodimensional grains aligned like a linear array. Scanning probe microscopy is used for investigating the ZnO surfaces and UV-visible spectroscopy for studying the effect of surface modification on optical properties. The two-dimensional power spectral density of the irradiated ZnO thin films have been evaluated for each image to extract the value of growth factor (β) and roughness exponent (α). The exponent n increases from 2.2 to 4.0 up to a critical value of fluence and beyond which it decreases. These values suggest that ion assisted∕induced diffusion process plays a crucial role in the evolution of self-affine nanostructures on ZnO surface.The topography evolution using the high energy heavy ion irradiation revealed the fact that ion bombardment produces self-affine nanostructures, creating peculiar surface morphologies and regular structures on the surface of the ZnO thin film at certain fluences. The self-affine nanopatterns produced on the surface of ZnO thin film under swift heavy ion irradiation are different types of nanostructures such as nanodimensional grains aligned like a linear array. Scanning probe microscopy is used for investigating the ZnO surfaces and UV-visible spectroscopy for studying the effect of surface modification on optical properties. The two-dimensional power spectral density of the irradiated ZnO thin films have been evaluated for each image to extract the value of growth factor (β) and roughness exponent (α). The exponent n increases from 2.2 to 4.0 up to a critical value of fluence and beyond which it decreases. These values suggest that ion assisted∕induced diffusion process plays a crucial role in the evolut...

Induction of apoptosis in Vero cells by Newcastle disease virus requires viral replication, de-novo protein synthesis and caspase activation

Newcastle disease virus causes (NDV) apoptotic death of infected cells. In the present study, the stimulus that provoked the induction of apoptosis in infected cells was examined. Vero cells infected with NDV developed apoptosis as characterized by DNA fragmentation and decreased DNA content. In presence of ammonium chloride, infected cells did not show reduced DNA content indicating the requirement of virus entry for the induction of apoptosis. UV-inactivated NDV did not induce apoptosis in cells suggesting the need of virus replication. Although cycloheximide blocked NDV-induced apoptosis, actinomycin-D did not, suggesting that de-novo viral protein synthesis was critical for the induction of apoptosis. In addition, activation of caspases was also detected by flowcytometry, indirect fluorescent and colorimetric assays. Based on the results, it was concluded that NDV-induced apoptosis in Vero cells required virus replication, de-novo protein synthesis and caspase activation.

HN protein of Newcastle disease virus causes apoptosis in chicken embryo fibroblast cells

Newcastle disease virus (NDV), an avian paramyxovirus, induces apoptosis in chicken embryo fibroblast (CEF) cells. In the present investigation, the ability of haemagglutinin-neuraminidase (HN) protein of NDV to cause apoptosis in CEF cells was examined. The results revealed that cells expressing the HN protein demonstrated decreased DNA content, phosphatidylserine exposure and increased cytoplasmic vacuolation. Up-regulation of caspase-1, -9, -8, -3, loss of mitochondrial transmembrane potential and an increase in oxidative stress were also observed in cells expressing the HN protein. Based on the above results it can be concluded that HN protein of NDV causes apoptosis in CEF cells.

Time course of Newcastle disease virus-induced apoptotic pathways.

Newcastle disease virus (NDV) causes economically significant Newcastle disease (ND) in almost all birds worldwide. Previous studies have shown that NDV induces caspase dependent apoptotic pathways in infected cells. In the present study, time course induction of apoptotic pathways in Vero cells is described. In NDV-infected cells, caspase-8 activity, percentage of cells showing TRAIL expression was higher at 24h p.i. (post-infection) compared to 48 h p.i. In contrast, caspase-9 activity, efflux of cytochrome c, loss of mitochondrial membrane potential was higher at 48 h compared to 24h p.i. The caspase-3 activity was high both times. Based on these results, it was concluded that at 24h p.i., NDV induces apoptosis through extrinsic apoptotic pathway while at 48 h p.i. predominantly through intrinsic apoptotic pathway.

Virtual business empires at Second Life

The participants gathered hours before the beginning of the event in January 2007 to occupy their virtual space for the scheduled event. All dressed in the best of the costumes to attend the long awaited event at the virtual business centre. One of the attendees tried big shiny eyes and long black hairs for the meeting and shortly afterwards flew to music island waiting for the music band to appear. The virtual world may sound futuristic where users can fly, swim, collaborate in real time and all this is part of a virtual world of Second Life (SL). The case draws focus on virtual world of SL and how corporates can exploit the benefits to use it for collaboration, marketing and promotion. The case explores hurdles encountered by users while using SL platform.

SaaS Empowered Innovative On-Demand Software Applications: Potential and Challenges of the Cloud

The current business environment has migrated more towards distributed systems. Company offices are located in dispersed geographical locations worldwide, leading to the sheer need for a collaborative dispersed workplace. Business has transformed to a great extent from being physically limited to office locations to becoming atomized and distributed. To keep pace with the evolving workplace the business challenge is to establish an effective collaborative environment that would work across dispersed environments, helping it to stay connected and work seamlessly with anyone anywhere instantaneously. The drift in the scenario has led software vendors to adapt to the challenge of delivering more value to customers. The challenge is not confined to software delivery and support but also concerns how to make critical information more accessible and usable for knowledge workers.

Digital content delivery and monetisation issues at vReach

vReach, a digital media company is a pioneer in design and development of interactive digital content for various conferences and summits held across India. Their core product offering used to be fusion of video, PowerPoint, audio, text, animation and graphics. Thus, they provided a more interactive experience of the event to users. The company had complete capability, from media acquisition to distribution, with support for all media formats, under its own control. The product was further extended to the user through the medium of internet/intranet – in a form of webcast. Two years ago, the company decided to provide digital content on the web to its customers to get a competitive advantage. The company invested heavily in terms of money and manpower on the project. But, this was not as successful as anticipated. The case explores the hurdles encountered in deployment of the product in a form of Software as a Service (SaaS) on the web. This case focuses on the technical, schedule and financial feasibility issues which occurred during the implementation phase.