Biomimetic protein‐based elastomeric hydrogels for biomedical applications

In recent years, protein‐based elastomeric hydrogels have gained increased research interest in biomedical applications for their remarkable self‐assembly behaviour, tunable 3D porous structure, high resilience (elasticity), fatigue lifetime (durability), water uptake, excellent biocompatibility and biological activity. The proteins and polypeptides can be derived naturally (animal or insect sources) or by recombinant (bacterial expression) routes and can be crosslinked via physical or chemical approaches to obtain elastomeric hydrogels. Here we review and present the recent accomplishments in the synthesis, fabrication and biomedical applications of protein‐based elastomeric hydrogels such as elastin, resilin, flagelliform spider silk and their derivatives. © 2013 Society of Chemical Industry     

Steady states of continuous-time open quantum walks

Continuous-time open quantum walks (CTOQW) are introduced as the formulation of quantum dynamical semigroups of trace-preserving and completely positive linear maps (or quantum Markov semigroups) on graphs. We show that a CTOQW always converges to a steady state regardless of the initial state when a graph is connected. When the graph is both connected and regular, it is shown that the steady state is the maximally mixed state. As shown by the examples in this article, the steady states of CTOQW can be very unusual and complicated even though the underlying graphs are simple. The examples demonstrate that the structure of a graph can affect quantum coherence in CTOQW through a long-time run. Precisely, the quantum coherence persists throughout the evolution of the CTOQW when the underlying topology is certain irregular graphs (such as a path or a star as shown in the examples). In contrast, the quantum coherence will eventually vanish from the open quantum system when the underlying topology is a regular graph (such as a cycle).     

Plasma-deposited fluorocarbon films: insulation material for microelectrodes and combined atomic force microscopy-scanning electrochemical microscopy probes

Pinhole-free insulation of micro- and nanoelectrodes is the key to successful microelectrochemical experiments performed in vivo or in combination with scanning probe experiments. A novel insulation technique based on fluorocarbon insulation layers deposited from pentafluoroethane (PFE, CF3CHF2) plasmas is presented as a promising electrical insulation approach for microelectrodes and combined atomic force microscopy-scanning electrochemical microscopy (AFM-SECM) probes. The deposition allows reproducible and uniform coating, which is essential for many analytical applications of micro- and nanoelectrodes such as, e.g., in vivo experiments and SECM experiments. Disk-shaped microelectrodes and frame-shaped AFM tip-integrated electrodes have been fabricated by postinsulation focused ion beam (FIB) milling. The thin insulation layer for combined AFM-SECM probes renders this fabrication technique particularly useful for submicro insulation providing radius ratios of the outer insulation versus the disk electrode (RG values) suitable for SECM experiments. Characterization of PFE-insulated AFM-SECM probes will be presented along with combined AFM-SECM approach curves and imaging.     

Structural,optical and electrical properties of ZnTe<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Se<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> thin films

ZnTe_1−x Se _x films were deposited on glass substrates kept at 200 °C by the electron beam evaporation technique. These films exhibited cubic structure and the lattice parameter increased with increase of Tellurium concentration in the films which confirmed the solid solution formation. The grain size is found to increase with Te content. The dislocation density and lattice strain show a decreasing trend with increasing of Te content. Band gap values of 2.73 eV, 2.63 eV, 2.52 eV and 2.41 eV have been calculated for the films of composition ‘x’ = 0.2, 0.4, 0.6 and 0.8, respectively, which confirmed the formation of solid solution between ZnSe and ZnTe. Refractive index of the films increased from 2.535 to 2.826 as the concentration of Te increased. All the films showed high resistivity values. Laser Raman spectral studies of ZnTe_1−x Se _x revealed LO phonon frequencies whose values are located in between the LO phonon frequencies of ZnSe and ZnTe.     

Power system remedial action methodology

The authors address the problem of remedial-action computations for the purpose of alleviating overloads, abnormal voltages, etc. The method is based on a linear programming (LP) approach. Applications for voltage/reactive-power control, discrete capacitor/reactor switching, load transfer, and interchange control are considered. The method is optionally based on a DC or AC network model. It utilizes a number of innovations to yield an efficient computational procedure. The major innovations are: a procedure for determining coherent constraints which results in a fast identification of active constraints, fast linearization procedures for active constraints, procedures to define the region of validity of the linearized model, and a fast sparsity-coded LP algorithm. The performance of the method for large power systems is evaluated     

An application of Keller's method to the solution of an eighth-order nonlinear boundary value problem

An efficient implicit finite difference method, called the Keller's box scheme, is applied to solve an eighth-order nonlinear two-point boundary value problem. The example considered here is the compressible boundary layer equations at a general three-dimensional stagnation point. The solutions obtained are compared with results from other methods and the potential advantages of the method are demonstrated.     

Acalypha indica–mediated green synthesis of ZnO nanostructures under differential thermal treatment: Effect on textile coating,hydrophobicity, UV resistance,and antibacterial activity

In this study, ZnO nanoparticles were green-synthesized from Acalypha indica leaf extract using zinc acetate as a precursor. The prepared ZnO nanoparticles were calcined at three different temperatures, namely 100, 300, and 600?°C. The structure/morphology of the green-synthesized ZnO nanoparticles was ascertained through X-ray diffraction, particle size analysis, scanning electron microscopy, transmission electron microscopy, and surface area analysis techniques. It was observed from the physico-chemical and biological characterization studies that ZnO nanoparticles calcined at high temperature (600?°C) exhibit high surface area (230?m²?g^?1) and small particle size (20?nm) with good antibacterial activity against Escherichia coli (22.89?±?0.06?mm) and Staphylococcus aureus (24.62?±?0.08?mm). In addition, cotton fabrics coated with these nanoparticles showed higher UV-protection (87.8?UPF), hydrophobicity (155°), and maximum zone of bacterial inhibition against E. coli and S. aureus (25.13?±?0.05 mm and 30.17?±?0.03?mm) than those coated with particles calcined at 100?°C and 300?°C. High temperature calcination has a vital role in the crystallization of the particles towards nanoscale with increased resistivity to UV exposure, washing treatments, and microbial infection in fabrics. Thus, the cost-effective ZnO nanoparticles obtained through green synthesis method proves their potential applications in the field of biomedical, textile, and cosmetic applications.     

Optoelectronic,magnetic and antibacterial properties of CdO thin films doubly doped with Mn (cationic) and F (anionic) ions

This paper outlines the effect of (Mn?+?F) double doping on the structural, morphological, optoelectronic, magnetic and antibacterial properties of CdO thin films. Undoped CdO, Mn-doped CdO and (Mn?+?F) doubly doped CdO films exhibit face-centered cubic structure with a strong (1 1 1) preferential growth. Crystallite size value of the undoped film estimated using the Scherrer formula decreases with Mn doping and with double doping it increases. Cauliflower shaped nanostructures are evinced from the SEM images. Increased optical transparency is observed for the doubly doped films. The optical band gap value of the Mn-doped CdO film is found to be red shifted and for the (Mn?+?F) doubly doped films it is blue shifted which may be attributed to the Moss-Burstein effect. Ferromagnetic ordering is observed for the doped films. The doped films show increased antibacterial efficiency against K. pneumonia a gram ?ve bacteria. The obtained results infer that the CdO films doubly doped with Mn (cationic) and F (anionic) ions exhibited better optical, electrical, magnetic and antibacterial properties.     

Influence of ball milling on the particle size and antimicrobial properties of Tridax procumbens leaf nanoparticles

The herbal nanoparticles were prepared from shade dried Tridax procumbens plant leaves employing ball milling technique using different process parameters, like ball ratio/size and milling time. The obtained nanoparticles were comprehensively characterised using X‐ray diffraction, Fourier transform infrared spectroscopy, UV–visible spectroscopy, dynamic light scattering, scanning electron microscopy and antimicrobial analysis techniques. The crystallinity of the nanoparticles was retained without altering even though the particle size changes due to milling periods. The antibacterial activities of the prepared herbal nanoparticles against Staphylococcus aureus and Escherichia coli were explored to understand the influence of particle size on antimicrobial activities and their functional properties. The increase in ball ratio and milling time periods leads to a decrease in nanoparticle size from 114 to 45 nm which in turn increases the antimicrobial activities. The above study confirms that antimicrobial activity relies on nanoparticle size. The observed knowledge on influence of particle size on antimicrobial activities will help to optimise the production of potential herbal nanoparticles for different biomedical applications.Inspec keywords: nanoparticles, antibacterial activity, biomedical materials, nanomedicine, X‐ray diffraction, Fourier transform infrared spectra, scanning electron microscopy, ultraviolet spectra, visible spectra, microorganisms, particle sizeOther keywords: antimicrobial properties, Tridax procumbens leaf nanoparticles, herbal nanoparticles, ball milling technique, X‐ray diffraction, Fourier transform infrared spectroscopy, UV‐visible spectroscopy, dynamic light scattering, scanning electron microscopy, antimicrobial analysis techniques, Staphylococcus aureus, Escherichia coli, nanoparticle size     

SEAI: Secrecy and Efficiency Aware Inter-gNB Handover Authentication and Key Agreement Protocol in 5G Communication Network

Recently, the Third Generation Partnership Project (3GPP) has initiated the research in the Fifth Generation (5G) network to fulfill the security characteristics of IoT-based services. 3GPP has proposed the 5G handover key structure and framework in a recently published technical report. In this paper, we evaluate the handover authentication mechanisms reported in the literature and identify the security vulnerabilities such as violation of global base-station attack, failure of key forward/backward secrecy, de-synchronization attack, and huge network congestion. Also, these protocols suffer from high bandwidth consumption that doesn’t suitable for energy-efficient mobile devices in the 5G communication network. To overcome these issues, we introduce Secrecy and Efficiency Aware Inter-gNB (SEAI) handover Authentication and Key Agreement (AKA) protocol. The formal security proof of the protocol is carried out by Random Oracle Model (ROM) to achieve the session key secrecy, confidentiality, and integrity. For the protocol correctness and achieve the mutual authentication, simulation is performed using the AVISPA tool. Also, the informal security evaluation represents that the protocol defeats all the possible attacks and achieves the necessary security properties.Moreover, the performance evaluation of the earlier 5G handover schemes and proposed SEAI handover AKA protocol is carried out in terms of communication, transmission, computation overhead, handover delay, and energy consumption. From the evaluations, it is observed that the SEAI handover AKA protocol obtains significant results and strengthens the security of the 5G network during handover scenarios.