Electrically conducting polypyrrole-fuller's earth nanocomposites: Their preparation and characterisation

Cu(II)-exchanged fuller's earth was prepared by ion-exchanging Ca²⁺ ions which are present within the interlayer of fuller's earth with Cu(II)ions by the solution-phase ion-exchange process. Pyrrole was introduced into Cu(II)-exchanged fuller's earth to spontaneously polymerize to within the interlayer to result in a nanocomposite of Cu(I)-polypyrrole-fuller's earth where both Cu(I) and polypyrrole occupy within the interlayer spaces of fuller's earth. The nanomaterial [Cu(I)-PPY-FE] has been fully characterized with X-ray diffraction studies, FTIR spectroscopy, DC polarisation test with both blocking stainless steel and non-blocking copper electrodes. The material is found to be a mixed conductor whose ionic mobility is 1.5 times faster than electronic mobility. DC polarisation studies also clearly revealed that the mobile ionic species in this material to be cuprous ions. AC impedance studies have been carried out with blocking stainless steel electrodes at different applied potentials. The necessary theoretical background to explain AC impedance results is also provided and the results obtained agree very well with the corresponding data obtained by other mutually independent methods. The electronic conductivities are around 3.0 × 10⁻⁴ S cm⁻¹ and the ionic conductivities are around 9.0 × 10⁻³ S cm⁻¹. The material may find applications in semi-fuel cells such as air-metal batteries.     

Pinostrobin Suppresses the α-Melanocyte-Stimulating Hormone-Induced Melanogenic Signaling Pathway

Pinostrobin is a dietary flavonoid found in several plants that possesses pharmacological properties, such as anti-cancer, anti-virus, antioxidant, anti-ulcer, and anti-aromatase effects. However, it is unclear if pinostrobin exerts anti-melanogenic properties and, if so, what the underlying molecular mechanisms comprise. Therefore, we, in this study, investigated whether pinostrobin inhibits melanin biosynthesis in vitro and in vivo, as well as the potential associated mechanism. Pinostrobin reduced mushroom tyrosinase activity in vitro in a concentration-dependent manner, with an IC₅₀ of 700 μM. Molecular docking simulations further revealed that pinostrobin forms a hydrogen bond, as well as other non-covalent interactions, between the C-type lectin-like fold and polyphenol oxidase chain, rather than the previously known copper-containing catalytic center. Additionally, pinostrobin significantly decreased α-melanocyte-stimulating hormone (α-MSH)-induced extracellular and intracellular melanin production, as well as tyrosinase activity, in B16F10 melanoma cells. More specifically, pinostrobin inhibited the α-MSH-induced melanin biosynthesis signaling pathway by suppressing the cAMP–CREB–MITF axis. In fact, pinostrobin also attenuated pigmentation in α-MSH-stimulated zebrafish larvae without causing cardiotoxicity. The findings suggest that pinostrobin effectively inhibits melanogenesis in vitro and in vivo via regulation of the cAMP–CREB–MITF axis.     

Sensitization of zinc oxide photoanode with an indoline dye

A dye‐sensitized solar cell (DSC) made of nanoporous ZnO film on aluminum‐doped zinc oxide (ZnO/AZO) transparent substrate has higher solar‐to‐electric energy conversion efficiency than a DSC consisting of nanoporous ZnO film deposited on conventional fluorine‐doped tin oxide (ZnO/FTO) transparent substrate. The ZnO/AZO DSC gave an overall conversion efficiency of 7.2% whereas the ZnO/FTO yielded a conversion efficiency of 4.5%. The film‐substrate orientation and higher light harvesting of the nanoporous ZnO film on the AZO after heating in air are mainly attributed to the higher energy conversion efficiency of the ZnO/AZO DSC. Copyright © 2012 John Wiley & Sons, Ltd.     

Evolutionary Minimization of Network Coding Resources

A method to identify feasible minimal network coding configurations between a source and a set of receivers without altering or modifying the established network infrastructure is proposed. The approach minimizes the resources used for multicast coding while achieving the desired throughput in the multicast scenario. Because the problem of identifying minimal configurations of a graph is known to be NP-hard, our method first identifies candidate minimal configurations and then searches for the optimal ones using a genetic algorithm (GA). Because the optimization process considers the number of coding nodes, the mean number of coding node input links and the sharing of resources by sinks, the problem is thus a multiobjective problem. Two multiobjective algorithms, MOGA and VEGA, are chosen to solve the problem because they are simple enough not to place heavy demands on source nodes when the minimal configuration is sought. The optimization process is investigated by the simulation of a range of randomly generated networks of varying sizes. Performance differences between the multiple-objective GAs are observed, which seem to arise from the difference in their methods of searching. Nevertheless, both methods perform well in terms of identifying feasible minimal configurations with optimized coding resources. The performance is assessed by comparing the optimized solutions with randomly chosen starting configurations. There are always reductions in the number of coding nodes used, typically 50%, and resource sharing is multiplied by several times. Typical mean in-link savings are 10% but may range from zero to close to 30%. We thus show that relatively simple multiple-objective GAs can deliver optimized minimal coding configurations for the network coding multicast problem. Moreover, the approach here offers an improvement over solutions in the literature because our method remains feasible for relatively large networks and its implementation at the source simplifies the functions that must be employed at intermediate nodes.     

Analysis and Experiment of Self-Powered,Pulse-Based Energy Harvester Using 400 V FEP-Based Segmented Triboelectric Nanogenerators and 98.2% Tracking Efficient Power Management IC for Multi-Functional IoT Applications

A self-powered system for the Internet of Things (IoT) is demonstrated for efficient energy harvesting of naturally available mechanical energy. In this system, new contact-separation mode triboelectric nanogenerators (TENGs), based on fluorinated ethylene propylene, are investigated using the segmented multi-TENG configuration to reduce the effect of parasitic capacitance. The TENG extraction is optimized using a unit step excitation involved with the Dawson function to achieve a high voltage (400 V) and a high current (26.6 µA). To fully extract the power of the TENGs, the power management integrated circuit (PMIC) specially designed for adaptively controlled, high-voltage (HV) maximum power point tracking (MPPT) is proposed. The PMIC implemented in a bipolar CMOS-DMOS 180 nm process can handle a wide input range (5–70 V) by consuming 420 nW. The MPPT control allows a wide range of impedance matching from 10 to 300 MΩ, achieving a tracking efficiency of up to 98.2%. The end-to-end efficiency of 88% demonstrates state-of-the-art performance. To supply a higher instantaneous power than that available from the TENGs, a duty-cycling technique is successfully demonstrated. The proposed energy harvesting system provides a promising approach to realizing sustainable and autonomous energy sources for various IoT applications.     

Numerical modelling of reinforced concrete columns subject to coupled uplift and shear forces induced by internal explosions

This article investigates the effect of time-variant coupled uplift forces and lateral blast pressures on the vulnerability of reinforced concrete columns when subjected to internal explosions. Detailed examination of archived events has demonstrated that confined blast can induce significant uplift forces on concrete columns carrying predominantly compression loads. These uplift forces can deteriorate the strength of concrete columns leading to destabilisation and a critical loss of structural adequacy. This research employs the applied element method together with high-resolution computational fluid dynamics simulations to model column response due to complex vented and contained internal blast environments. Results from a number of parametric studies highlighted the important effect of uplift forces and blast wave confinement with regard to the overall vulnerability of the column to internal building detonations. This research will be of direct importance to both practitioners and researchers involved with protective design of buildings.     

Double transition metal atoms anchored on Graphdiyne as promising catalyst for electrochemical nitrogen reduction reaction

Ammonia synthesis by electrochemical nitrogen reduction technique is an attractive alternative to tradi-tional Haber-Bosch process.Currently,development of an efficient and effective electrocatalyst is one of the remaining key challenges.In this work,density functional theory(DFT)computations were systemat-ically employed on double transition metal atoms(Fe,Co,Ni,Cu and Mo)anchored Graphdiyne(GDY)for nitrogen reduction reaction(NRR).The Co-Ni heteronuclear complex and Mo-Mo homonuclear complex showed the highest NRR activity while demonstrating synergistic effect of double atomic catalytic sites towards the promising NRR activity.     

Controlling software architecture erosion: A survey

Software architectures capture the most significant properties and design constraints of software systems. Thus, modifications to a system that violate its architectural principles can degrade system performance and shorten its useful lifetime. As the potential frequency and scale of software adaptations increase to meet rapidly changing requirements and business conditions, controlling such architecture erosion becomes an important concern for software architects and developers. This paper presents a survey of techniques and technologies that have been proposed over the years either to prevent architecture erosion or to detect and restore architectures that have been eroded. These approaches, which include tools, techniques and processes, are primarily classified into three generic categories that attempt to minimise, prevent and repair architecture erosion. Within these broad categories, each approach is further broken down reflecting the high-level strategies adopted to tackle erosion. These are: process-oriented architecture conformance, architecture evolution management, architecture design enforcement, architecture to implementation linkage, self-adaptation and architecture restoration techniques consisting of recovery, discovery and reconciliation. Some of these strategies contain sub-categories under which survey results are presented.We discuss the merits and weaknesses of each strategy and argue that no single strategy can address the problem of erosion. Further, we explore the possibility of combining strategies and present a case for further work in developing a holistic framework for controlling architecture erosion.     

Electrochemical investigation of superoxide anion scavenging ability of 1,2,3-triketohydrindene hydrate in aprotic solvents

1,2,3-Triketohydrindene hydrate (NHy) shows well-defined redox electrochemistry in the formation of monoanionic radical (NHy⁻) and dianion (NHy²⁻) in nitrogen saturated aprotic solvents such as acetonitrile and dimethylsulfoxide. Cyclic voltammetry reveals that in an oxygen-saturated solution of DMSO, the oxidation peak of superoxide anion (O₂⁻) at −0.7 V versus Ag/AgCl wire electrode, decreases systematically with increasing NHy concentration. The similar behaviour is observed in the rotating disk voltammetry. On Pt disk, oxygen is reduced to O₂⁻ at a constant potential of −0.8 V and at Pt ring, O₂⁻ is oxidised to oxygen and the corresponding limiting current plateau in the ring voltammogram is decreased linearly as [NHy] is increased. In aqueous solutions, NHy is found to exhibit completely different redox chemistry due to its structural changes and hence showed no favourable redox potentials for efficient quenching of O₂⁻.     

Scenario-based analyses of energy system development and its environmental implications in Thailand

Thailand is one of the fastest growing energy-intensive economies in Southeast Asia. To formulate sound energy policies in the country, it is important to understand the impact of energy use on the environment over the long-period. This study examines energy system development and its associated greenhouse gas and local air pollutant emissions under four scenarios in Thailand through the year 2050. The four scenarios involve different growth paths for economy, population, energy efficiency and penetration of renewable energy technologies. The paper assesses the changes in primary energy supply mix, sector-wise final energy demand, energy import dependency and CO₂, SO₂ and NO_x emissions under four scenarios using end-use based Asia-Pacific Integrated Assessment Model (AIM/Enduse) of Thailand.