Tunneling conduction in graphene/(poly)vinyl alcohol composites

Graphene/(Poly)vinyl alcohol (PVA) composite film with thickness $60 \mu m$ were synthesized by solidification of a PVA solution comprising of dispersed graphene nanosheets. The close proximity of the graphene sheets enables the fluctuation induced tunneling of electrons to occur from one sheet to another. The dielectric data show that the present system can be simulated to a parallel resistance-capacitor network. The high frequency exponent of the frequency variation of the ac conductivity indicates that the charge carriers move in a two-dimensional space. The sample preparation technique will be helpful for synthesizing flexible conductors.Comment: 10 pages, 8 figure

Graph theoretic network analysis reveals protein pathways underlying cell death following neurotropic viral infection

Complex protein networks underlie any cellular function. Certain proteins play a pivotal role in many network configurations, disruption of whose expression proves fatal to the cell. An efficient method to tease out such key proteins in a network is still unavailable. Here, we used graph-theoretic measures on protein-protein interaction data (interactome) to extract biophysically relevant information about individual protein regulation and network properties such as formation of function specific modules (sub-networks) of proteins. We took 5 major proteins that are involved in neuronal apoptosis post Chandipura Virus (CHPV) infection as seed proteins in a database to create a meta-network of immediately interacting proteins (1st order network). Graph theoretic measures were employed to rank the proteins in terms of their connectivity and the degree upto which they can be organized into smaller modules (hubs). We repeated the analysis on 2nd order interactome that includes proteins connected directly with proteins of 1st order. FADD and Casp-3 were connected maximally to other proteins in both analyses, thus indicating their importance in neuronal apoptosis. Thus, our analysis provides a blueprint for the detection and validation of protein networks disrupted by viral infections

Challenges of teaching engineering analysis software to distance education students

CONTEXT Engineering analysis software packages are regularly used in industry for solving problems. Therefore, it has become a necessity for the engineering academics to teach the students how to use software for solving problems. Academics face considerable challenges while teaching distance education students. The challenge arises not only from teaching the students we cannot see but also how the students access and use the software from home. In fact, providing proper software access to off-campus students (up to the students’ satisfaction) is not an easy task. The access process involves multiple technical issues. Diverse and dispersed student cohorts working in another part of the world at a different time zone, make the situation even trickier. The complexity increases further depending on how easy it is to learn the software and how technically involved the software is. PURPOSE In this paper, we present an example of how we are teaching the Strand7 software to our off-campus students at the University of Southern Queensland (USQ). The challenges we had faced over the years and the performances of various technologies that we have implemented, the learning and teaching activities we have designed, are discussed in detail. This paper can serve as a guide for options to teach software online. APPROACH We have implemented various technologies for providing remote access, and have designed learning and teaching activities for online teaching. In addition, we have provided recordings of live video tutorials as learning resources showing how to use the software Strand7. The performance of each technology was judged based on students’ satisfaction and whether the intended learning outcomes were achieved or not. RESULTS Progressively, we have implemented various technologies including Virtual Desktops, Remote Access Laboratories (RALs) and Virtual Private Networks (VPNs) for providing remote access. We have found that multiple technical factors, some of them beyond our control, affected the system performance badly. These technologies failed to provide viable long-term options for the online teaching of engineering analysis software. Therefore, we have explored other avenues. The current option in which the Strand7 Company provides the service to the students for a nominal charge is perhaps one of the best. Other options including the software CD provided by the Company for a limited period or the Student Version/Open Source software packages are also good. CONCLUSIONS Teaching online students how to use engineering analysis software packages comes with an additional challenge of providing remote access. We have trialled various technologies for providing this service with limited success. We found that other options including the service provided by the Company or Student Versions/Open Source software packages are perhaps better alternatives. We found that our designed learning and teaching activities along with the video tutorials helped the distance education students to achieve similar learning outcomes as the face-to-face students

Magnetodielectric effect in nickel nanosheet-Na-4 mica composites

Nickel nanosheets of thickness 0.6 nm were grown within the nanochannels of Na-4 mica template. The specimens show magnetodielectric effect at room temperature with a change of dielectric constant as a function of magnetic field, the electric field frequency varying from 100 to 700 kHz. A decrease of 5% in the value of dielectric constant was observed up to a field of 1.2 Tesla. This is explained by an inhomogeneous two-component composite model as theoretically proposed recently. The present approach will open up synthesis of various nanocomposites for sensor applications.Comment: 11 pages, 7 figure

Deposition of thin layers containing Ga, C and N by sequential pulses of Trimethylgallium and Ammonia

Gallium nitride (GaN) is a semiconductor with broad applications in the (opto-)electronic industry. State-of-the-art fabrication of GaN demands a nanometer-level control over layer thickness, which can be achieved with atomic layer deposition (ALD). Introducing carbon (C) into GaN layers, similar to introducing C into BN [1] or as a dopant in GaN [2], can facilitate control over material properties such as the band-gap and resistivity, respectively. In this work, we report on our results obtained from thermal deposition of layers, containing varying concentration of gallium (Ga), carbon (C) and nitrogen (N), from trimethylgallium (TMG) and ammonia (NH3) precursors. The precursors were sequentially introduced in a pulsed mode, i.e., without mixing them

Network analysis reveals common host protein/s modulating pathogenesis of neurotropic viruses

Network analysis through graph theory provides a quantitative approach to characterize specific proteins and their constituent assemblies that underlie host-pathogen interactions. In the present study, graph theory was used to analyze the interactome designed out of 50 differentially expressing proteins from proteomic analysis of Chandipura Virus (CHPV, Family: Rhabdoviridae) infected mouse brain tissue to identify the primary candidates for intervention. Using the measure of degree centrality, that quantifies the connectedness of a single protein within a milieu of several other interacting proteins, DJ-1 was selected for further molecular validation. To elucidate the generality of DJ-1’s role in propagating infection its role was also monitored in another RNA virus, Japanese Encephalitis Virus (JEV, Family: Flaviviridae) infection. Concurrently, DJ-1 got over-expressed in response to reactive oxygen species (ROS) generation following viral infection which in the early phase of infection migrated to mitochondria to remove dysfunctional mitochondria through the process of mitophagy. DJ-1 was also observed to modulate the viral replication and interferon responses along with low-density lipoprotein (LDL) receptor expression in neurons. Collectively these evidences reveal a comprehensive role for DJ-1 in neurotropic virus infection in the brain

Hot-Wire Assisted ALD: A Study Powered by In Situ Spectroscopic Ellipsometry

Hot-wire assisted atomic layer deposition (HWALD) is a novel energy-enhancement technique. HWALD enables formation of reactive species (radicals) at low substrate temperatures, without the generation of energetic ions and UV photons as by plasma. This approach employs a hot wire (tungsten filament) that is heated up to a temperature in the range of 1300–2000 °C to dissociate precursor molecules. HWALD has the potential to overcome certain limitations of plasma-assisted processes. This work investigates the ability of a heated tungsten filament to catalytically crack molecular hydrogen or ammonia into atomic hydrogen and nitrogen-containing radicals. The generation of these radicals and their successful delivery to the wafer (substrate) surface are experimentally confirmed by dedicated tellurium-etching and silicon-nitridation experiments. It further reports on deposition of low-resistivity oxygen-free tungsten films by using HWALD, as well as on the effect of hot-wire-generated nitrogen radicals and atomic hydrogen in deposition of aluminum nitride and boron nitride films. In parallel, this work provides important illustrative examples of using in situ real-time monitoring of deposition and etching processes, together with extracting a variety of film properties, by spectroscopic ellipsometry technique

Optical phase noise engineering via acousto-optic interaction and its interferometric applications

We exercise rapid and fine control over the phase of light by transferring digitally gen- erated phase jumps from radio frequency (rf) electrical signals onto light by means of acousto-optic interaction. By tailoring the statistics of phase jumps in the electrical signal and thereby engineering the optical phase noise, we manipulate the visibil- ity of interference fringes in a Mach-Zehnder interferometer that incorporates two acousto-optic modulators. Such controlled dephasing finds applications in modern experiments involving the spread or diffusion of light in an optical network. Further, we analytically show how engineered partial phase noise can convert the dark port of a stabilised interferometer to a weak source of highly correlated photons.Comment: 5 figure