Rationally engineered nanosensors: A novel strategy for the detection of heavy metal ions in the environment

Heavy metal ions (HMIs) have been mainly originated from natural and anthropogenic agents. It has become one of biggest societal issues due to their recognised accumulative and toxic effects in the environment as well as biological media. Key measures are required to reduce the risks posed by toxic metal pollutants existing in the environment. The increased research activities of HMIs detection, and use of technologies based on electrochemical detection that combine with engineered nanomaterials, is a key promising and innovative strategy that can potentially confine heavy metal poisoning. Deep understanding of the characteristics of the physicochemical properties of nanomaterials is highly required. It is also important to interpret the parameters at the nano-bio interface level that merely affect cross-interactions between nanomaterials and HMIs. Therefore, the authors outlined the state-of-the-art techniques that used engineeringly developed nanomaterials to detect HMIs in the environment. The possible novel applications of extensive and relatively low-cost HMIs monitoring and detection are discussed on the basis of these strengths. Finally, it is concluded by providing gist on acquaintance with facts in the present-day scenario along with highlighting areas to explore the strategies to overcome the current limitations for practical applications is useful in further generations of nano-world

Paper Thermoelectrics by a Solvent-Free Drawing Method of All Carbon-Based Materials

As practical interest in the flexible or wearable thermoelectric generators (TEGs) has increased, the demand for the high-performance TEGs based on ecofriendly, mechanically resilient, and economically viable TEGs as alternatives to the brittle inorganic materials is growing. Organic or hybrid thermoelectric (TE) materials have been employed in flexible TEGs; however, their fabrication is normally carried out using wet processing such as spin-coating or screen printing. These techniques require materials dissolved or dispersed in solvents; thus, they limit the substrate choice. Herein, we have rationally designed solvent-free, all carbon-based TEGs dry-drawn on a regular office paper using few-layered graphene (FLG). This technique showed very good TE parameters, yielding a power factor of 97 μW m–1 K–2 at low temperatures. The p-type only device exhibited an output power of up to ∼19.48 nW. As a proof of concept, all carbon-based p-n TEGs were created on paper with the addition of HB pencil traces. The HB pencil exhibited low Seebeck coefficients (−7 μV K–1), and the traces were highly resistive compared to FLG traces, which resulted in significantly lower output power compared to the p-type only TEG. The demonstration of all carbon-based TEGs drawn on paper highlights the potential for future low-cost, flexible, and almost instantaneously created TEGs for low-power applications

Financial cointegration and spillover effect of global financial crisis: a study of emerging Asian financial markets

This paper examines the financial cointegration and spillover effect of the global financial crisis to emerging Asian financial markets (India, China, Pakistan, Malaysia, Russia and Korea). The analysis used daily stock returns, divided into three time periods: pre-, during and post-crisis from 1 July 2005 to 30 June 2015. We applied the Johansen and Juselius cointegration test, the vector error correction model (V.E.C.M.) and the G.A.R.C.H.-B.E.K.K. model for an examination of integration and conditional volatility. We find long-term cointegration between the U.S. market and emerging stock markets, and the level of cointegration increased after the crisis period. The V.E.C.M. and impulse response function reveal that a shock in the U.S. financial market has a short-term impact on the returns of emerging financial markets. Past shocks and volatility have more effect on the selected stock markets during all time periods. The Korea Composite Stock Price Index and the Bombay stock exchange (B.S.E.) are the only stock markets that have cross-market news and volatility spillover effects during the crisis period. After the crisis period, news effects are positive on the B.S.E. and the Russian Trading System and have a negative effecton the Kuala Lumpur Stock Exchange and the Shanghai Stock Exchange

Blockchain Based Secure Interoperable Framework for the Internet of Medical Things

Internet of Medical Things (IoMT) has revolutionized the way medical infrastructure has been managed in the past. Multiple platforms in IoMT have disparate communication standards, data format requirements, and access policies, which produce immense overhead during data transfer among these platforms. In order to provide seamless healthcare services using IoMT, interoperability concerns of heterogeneous devices need to be addressed. Smart contracts using blockchain provide a secure communication for distributed objects to interact in a secure way. We propose a Blockchain-based Secure Interoperable Framework (BSIIoMT) using smart contracts for secure communication in IoMT. We present components, workflow, and design considerations of the BSIIoMT framework to show the feasibility of using edge-enabled blockchain for secure interoperability in IoMT. The BSIIoMT framework is an ongoing project where we present the framework and its components in this research where further results and evaluation will be presented in future

Highly sensitive capacitive cell based on a novel CuTsPc-TiO2 nanocomposite electrolytic solution for low-temperature sensing applications

This work demonstrates a highly efficient electrochemical cell based on the hybrid nanofluid of titanium dioxide (TiO2) nanoparticles dispersed in a water-based copper (II) phthalocyanine-tetrasulfonic acid tetrasodium salt (CuTsPc) solution. A chemical cell of ITO/nanofluid/ITO has been fabricated to study the effect of temperature variations towards its capacitance and resistance. The resultant device possessed capacitive sensing mechanism, and the synergistic hybridization of the two different sensing elements lead to the superior performance as compared to the single CuTsPc based device. The hybrid device outperformed the pristine CuTsPc based device in terms of sensitivity, stability, linearity, response/recovery and possessed narrow hysteresis loop

Density functional theory simulation of cobalt oxide aggregation and facile synthesis of a cobalt oxide, gold and multiwalled carbon nanotube based ternary composite for a high performance supercapattery

A novel ternary composite consisting of cobalt oxide (Co3O4) nanoparticles (NPs) grown on multiwalled carbon nanotubes (MWCNTs) and mixed with gold (Au) NPs is synthesized by a single step hydrothermal route. Initially, density functional theory (DFT) simulations were carried out to model the aggregation of Co3O4 NPs and validated further with experimental results. To circumvent this issue, MWCNTs with gold NPs were introduced, which significantly reduced the particle aggregation. Standard three electrode cell studies revealed that the Co3O4/Au@MWCNT composite possesses an excellent energy density, rate capability and very good cyclic stability compared to unsupported Co3O4 or the binary Co3O4@MWCNT. The promising electrochemical performance compared to the single Co3O4 or the binary Co3O4@MWCNT materials is assigned to the synergetic effects of MWCNTs and Au to disaggregate the Co3O4 NPs and to enhance the overall conductivity, respectively. In order to get insight into the evaluation of the performance, two electrode devices were assembled employing activated carbon as a negative electrode and the Co3O4/Au@MWCNT composite as a positive electrode material. The two electrode supercapattery device demonstrated splendid cycling stability with a retention value of 91.90% in 1 M KOH for over 3500 cycles. Additionally, it exhibited an excellent energy density of 18.80 W h kg-1 at a power density of 302.00 W kg-1. These encouraging outcomes can be associated with the distinctive morphology, outstanding conductive networks, increased electroactive sites, and emergence of strong networking of Co3O4, MWCNT and Au in the ternary composite. This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique

UV- ozone treated graphene oxide/ PEDOT:PSS bilayer as a novel hole transport layer in highly efficient and stable organic solar cells

The utilization of UV-ozone (UVO) treated graphene oxide (GO)/PEDOT:PSS bilayer as hole transport layer (HTL) in solution processed organic solar cells (OSCs) is demonstrated. The HTLs were treated with UVO for 0, 5, 10 and 15 min. The 10 min treated OSC showed the best performance and displayed power conversion efficiency (PCE) of 5.24%, much higher than the untreated OSC device. This enhanced performance is mainly driven by improvements in the short circuit current (∼10.82 mA/cm2) as well as the fill factor (∼57%) that is ascribed to the moderate reduction of GO and increased work function (WF) of PEDOT:PSS after UVO treatment, which improved the contact conditions between the HTL and photoactive layer. Consequently, extraction efficiency of the photogenerated holes is increased, while recombination probability of holes and electrons in the photoactive layer is decreased. Moreover, the UVO-reduction of GO and consequently increased conductivity of reduced-GO (r-GO) has been modeled and proved using the density functional theory (DFT) simulation. Meanwhile, the 15 min UVO-treated OSC device showed severe reduction in the PCE that dropped to 2.11%, possibly due to couple of factors such as decomposition of chemical bonds, significant increase in the series resistance and pronounced drop in the photovoltaic performance parameters

Analysing and Modelling the Corrosion Behavior of Ni/Al2O3, Ni/SiC, Ni/ZrO2 and Ni/Graphene Nanocomposite Coatings

A study has been presented on the effects of intrinsic mechanical parameters, such as the surface stress, surface elastic modulus, surface porosity, permeability and grain size on the corrosion failure of nanocomposite coatings. A set of mechano-electrochemical equations was developed by combining the popular Butler-Volmer and Duhem expressions to analyse the direct influence of mechanical parameters on the electrochemical reactions in nanocomposite coatings. Nanocomposite coatings of Ni with Al2O3, SiC, ZrO2 and Graphene nanoparticles were studied as examples. The predictions showed that the corrosion rate of the nanocoatings increased with increasing grain size due to increase in surface stress, surface porosity and permeability of nanocoatings. A detailed experimental study was performed in which the nanocomposite coatings were subjected to an accelerated corrosion testing. The experimental results helped to develop and validate the equations by qualitative comparison between the experimental and predicted results showing good agreement between the two