Carbon microtubes: tuning internal diameters and conical angles

In this paper, we report a synthesis strategy for a new class of hollow, curved carbon morphologies, 'carbon microtubes' (CMTs), with absolute control over their conical angles and internal diameters. Our synthesis methodology employs nitrogen or oxygen dosing to change the wetting behaviour of gallium metal with the growing carbon walls to tune the conical angles. Increasing N(2) concentrations in the gas phase during growth increases the conical angles of CMTs from +25° to about -20°. A methodology using the timing of oxygen or nitrogen dosing during CMT growth is shown to tune the internal diameters anywhere from a few nanometres to a few microns. The walls of the carbon microtubes are characterized using transmission electron microscopy (TEM) and Raman spectroscopy and are found to consist of aligned graphite nanocrystals (2-5?nm in size). Furthermore, dark field images of CMTs showed that the graphite nanocrystals are aligned with their c-axes perpendicular to the wall surface and that the crystals themselves are oriented with respect to the wall surface depending upon the conical angle of the CMT.     

Au/SnO2 an excellent material for room temperature carbon monoxide sensing

Tin dioxide synthesized by the hydrothermal method, impregnated with Au has been used for the room temperature carbon monoxide sensing in air. Incorporation of poly ethylene glycol (PEG-6000) as a modifier during the synthesis procedure results in well dispersed nanosized particles of SnO₂ which influence the sensing capability dramatically. This tailored morphology leads to development of a material with improved sensor response. Incorporation of gold resulted in a composition that was capable of selectively sensing low concentrations (upto 10 ppm CO in air) at temperatures below 50 °C. The mechanism of improved sensing has been explained based on the gas sensing characteristics with support from TEM, UV-DRS, XPS and FTIR.     

Distributed, multi-sensor tracking of multiple participants within immersive environments using a 2-cohort camera setup

Vision-based human motion tracking has gained significant interest in recent years, as the need for more intuitive human–computer interaction paradigms are sought after. Immersive environments, such as large-scale displays and virtual reality systems are particularly suitable for such interaction mechanisms, as they provide a controlled basis for experimentation and evaluation. However, despite the growing interest, human-motion tracking within immersive environments is still in its infancy. The lack of visible light and the presence of multiple people within such environments pose several challenges to the problem. In this research a robust framework for real-time, multi-camera human-motion tracking within an immersive environment is presented. The static nature of the environment is exploited to utilise a novel 2-cohort camera layout. This layout proves to be highly useful for tracking, providing several benefits over existing techniques, which treat all cameras as the same.     

Chitin scaffolds in tissue engineering

Tissue engineering/regeneration is based on the hypothesis that healthy stem/progenitor cells either recruited or delivered to an injured site, can eventually regenerate lost or damaged tissue. Most of the researchers working in tissue engineering and regenerative technology attempt to create tissue replacements by culturing cells onto synthetic porous three-dimensional polymeric scaffolds, which is currently regarded as an ideal approach to enhance functional tissue regeneration by creating and maintaining channels that facilitate progenitor cell migration, proliferation and differentiation. The requirements that must be satisfied by such scaffolds include providing a space with the proper size, shape and porosity for tissue development and permitting cells from the surrounding tissue to migrate into the matrix. Recently, chitin scaffolds have been widely used in tissue engineering due to their non-toxic, biodegradable and biocompatible nature. The advantage of chitin as a tissue engineering biomaterial lies in that it can be easily processed into gel and scaffold forms for a variety of biomedical applications. Moreover, chitin has been shown to enhance some biological activities such as immunological, antibacterial, drug delivery and have been shown to promote better healing at a faster rate and exhibit greater compatibility with humans. This review provides an overview of the current status of tissue engineering/regenerative medicine research using chitin scaffolds for bone, cartilage and wound healing applications. We also outline the key challenges in this field and the most likely directions for future development and we hope that this review will be helpful to the researchers working in the field of tissue engineering and regenerative medicine.     

Electrical and Electromagnetic Interference (EMI) shielding properties of hexagonal boron nitride nanoparticles reinforced polyvinylidene fluoride nanocomposite films

The hexagonal boron nitride nanoparticles (h-BNNPs) reinforced flexible polyvinylidene fluoride (PVDF) nanocomposite films were prepared via a simple and versatile solution casting method. The morphological, thermal and electrical properties of h-BNNPs/PVDF nanocomposite films were elucidated. The electromagnetic interference (EMI) shielding properties of prepared nanocomposite films were investigated in the X-band frequency regime (8–12 GHz). The EMI shielding effectiveness (SE) was increased from 1 dB for the PVDF film to 11.21 dB for the h-BNNPs/PVDF nanocomposite film containing 25 wt% h-BNNPs loading. The results suggest that h-BNNPs/PVDF nanocomposite films can be used as lightweight and low-cost EMI shielding materials.     

Dynamic video anomaly detection and localization using sparse denoising autoencoders

The emergence of novel techniques for automatic anomaly detection in surveillance videos has significantly reduced the burden of manual processing of large, continuous video streams. However, existing anomaly detection systems suffer from a high false-positive rate and also, are not real-time, which makes them practically redundant. Furthermore, their predefined feature selection techniques limit their application to specific cases. To overcome these shortcomings, a dynamic anomaly detection and localization system is proposed, which uses deep learning to automatically learn relevant features. In this technique, each video is represented as a group of cubic patches for identifying local and global anomalies. A unique sparse denoising autoencoder architecture is used, that significantly reduced the computation time and the number of false positives in frame-level anomaly detection by more than 2.5%. Experimental analysis on two benchmark data sets - UMN dataset and UCSD Pedestrian dataset, show that our algorithm outperforms the state-of-the-art models in terms of false positive rate, while also showing a significant reduction in computation time.     

Automated image processing for grain boundary analysis

The image processing used in the automated analysis of grain boundaries and triple junctions in scanning electron microscopy images is described. The required image processing includes the location of grain boundaries and triple junctions, calculation of the dihedral angles at triple junctions, and selection of electron backscatter probe points (to obtain grain orientation data).     

Corrosion protection ability of plasma-deposited amorphous hydrogenated carbon and fluorocarbon films

Hydrogenated diamond-like carbon and fluorocarbon films, deposited in a radio-frequency (rf) plasma reactor, have high chemical inertness and high electrical resistivity. These films, deposited on aluminum and type 301 stainless steel substrates at several rf power and feed gas flow rates using different gas phase precursors, were characterized for their pinhole density and stability with exposure to 0.6 M NaCl and 0.1 M NaCl and 0.1 M Na₂SO₄ solutions using electrochemical impedance spectroscopy and potentiostatic techniques, respectively. The results from electrochemical characterizations with salt water exposure indicated that films with high effective pore resistances (>10⁸ Ω · cm²)* and high stability with exposure (<10% changes in capacitance values) can be obtained over a narrow range of process conditions and gas phase compositions.     

Synthesis of low-melting metal oxide and sulfide nanowires and nanobelts

The bulk nucleation and basal growth of semiconducting nanowires from molten Ga pools has been demonstrated earlier using oxygen/hydrogen plasma over molten Ga pools. Herein, we extend the above concept for bulk synthesis of oxide and sulfide nanowires of low-melting metal melts such as Sn and In. Specifically, nanowires of β-Ga₂O₃, β-In₂O₃, SnO₂, α-Ga₂S₃, and β-In₂S₃ were synthesized using direct reactions between respective molten metal pools and the gases such as oxygen/hydrogen mixture for oxides and H₂S for sulfides. In the case of β-Ga₂O₃ and SnO₂, a change in the morphology from nanowires to nanobelts was observed with an increase in the synthesis temperature. No such behavior was observed in the case of β-In₂O₃. Furthermore, we present evidence for α-Ga₂S₃ nanowires, which to our knowledge is being reported for the first time in the literature. Our studies with the sulfide nanowires suggest that H₂S reacts directly at the molten metal surface to form gallium sulfide. Finally, we discuss the role of chamber pressure and hydrogen on the size distribution of nanostructured β-Ga₂O₃ and SnO₂.     

Core-shell MoO3-MoS2 nanowires for hydrogen evolution: a functional design for electrocatalytic materials

We synthesize vertically oriented core-shell nanowires with substoichiometric MoO(3) cores of ～20-50 nm and conformal MoS(2) shells of ～2-5 nm. The core-shell architecture, produced by low-temperature sulfidization, is designed to utilize the best properties of each component material while mitigating their deficiencies. The substoichiometric MoO(3) core provides a high aspect ratio foundation and enables facile charge transport, while the conformal MoS(2) shell provides excellent catalytic activity and protection against corrosion in strong acids.