Graphene oxide grafted poly(acrylic acid) synthesized via surface initiated RAFT as a pH-responsive additive for mixed matrix membrane

Incorporation of nanostructured materials into the membrane matrix is a new strategy to improve mechanical and performance properties. Graphene oxide (GO) is one of the advantageous carbon-based nanomaterials, which recently has been used extensively in this field. However, in the most cases, the surface modification of GO has been considered for the creation of new properties like a response to different stimuli such as temperature, pH, and pressure. In the present study, a well-defined poly(acrylic acid) was grafted on GO using reversible addition–fragmentation chain transfer polymerization technique. This modified GO was incorporated into the mixed matrix membrane as a pH-sensitive additive and its effect on the membrane performance was investigated. The membrane with 5 wt % of modified GO provides better hydrophilicity, flux, antifouling, and rejection properties and so the effect of pH change on the aforementioned characteristic properties was studied for this membrane. It is indicated that modified membrane shows different behaviors in acidic and alkaline conditions. In addition, excellent heavy metal separation was observed among rejection tests, especially for Hg ions. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47213.     

Utility of silver‐coated fabrics as electrodes in electrotherapy applications

The present study deals with the deposition of silver particles onto knitted fabrics for possible applications in electrotherapy. The performance of silver‐coated fabrics was evaluated based on number of properties such as electrical conductivity, physiological comfort, antibacterial, and durability. Furthermore, the conductive fabrics were subjected to various repeated extensions and change in electrical resistivity was examined to simulate the performance of electrodes under various movements of human body. With increase in extension till 80%, very small change in volume electrical resistance was observed and after 90% extension, the electrical resistance was found to increase significantly. The volume resistance was found to remain constant for repeated extensions of over 100 cycles and also there was insignificant change in electrical resistivity when constant current was applied over prolonged time. The utility of silver‐coated fabrics can be expected as flexible textile electrodes in transcutaneous electrical nerve stimulation electrotherapy applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46357.     

Photocatalytic removal of NOx over immobilized BiFeO<Subscript>3</Subscript> nanoparticles and effect of operational parameters

Perovskite type BiFeO₃ (BFO) was synthesized by sol-gel auto-combustion method. Synthesized BFO was immobilized on the micro slides glass plates by sol-gel dip-coating method. The sample was characterized by XRD, FESEM, UV-Vis DRS, and BET techniques. The XRD pattern confirmed the perovskite structure, and from the Debye-Scherrer equation the average crystalline size was calculated as 19 nm. The FE-SEM images of prepared BFO showed porous structure with low agglomeration. The band gap energy was calculated about 2.13 eV, and the specific surface area (SSA) of prepared BFO nanostructure was obtained 55.1m² g^?1. The photocatalytic activity of prepared pure and immobilized BFO was investigated in the removal of NOx under UV irradiation, in the batch photoreactor. The effects of operational parameters such as initial concentration of NOx, light intensity and amount of coated photocatalyst, under identical conditions, were investigated. The results showed that the highest conversion of NOx was obtained as 35.83% in the 5 ppm of NOx with 1.2 g immobilized BFO and under 15 W illumination lamp.     

Diffusion augmented complex adaptive IIR algorithm for training widely linear ARMA models

In this paper, our aim is to propose a fully distributed adaptive algorithm for learning the parameters of a widely linear autoregressive moving average model by measurements collected by a network. To this end, we consider a connected network where every node uses the augmented complex adaptive infinite impulse response (ACA-IIR) filter as the learning rule. We firstly formulate the learning problem as an optimization problem and resort to stochastic gradient optimization argument to solve it and derive the proposed algorithm, which will be referred to as diffusion ACAIIR (DACA-IIR) algorithm. We also introduce a reduced-complexity version of the DACA-IIR algorithm. We use both synthetic and real-world signals in our simulations where the results show that the proposed cooperative algorithm outperforms the noncooperative solution.     

Structural,elastic, optoelectronic and magnetic properties of $$\mathbf{CdHo }_\mathbf{2}{} \mathbf{S}_\mathbf{4}$$ spinel: a first-principle study

We report the results of the full-potential linearized augmented plane wave (FP-LAPW) calculations on the structural, elastic, optoelectronic and magnetic properties of \(\hbox {CdHo}_{2}\hbox {S}_{4}\) spinel. Both the generalized gradient approximation (GGA) and Trans-Blaha modified Becke-Johnson potential (TB-mBJ) are used to model the exchange-correlation effects. The computed lattice parameter, internal coordinate and bulk modulus are in good agreement with the existing experimental data. According to the calculated elastic moduli, \(\hbox {CdHo}_{2}\hbox {S}_{4}\) is mechanically stable with a ductile nature and a noticeable elastic anisotropy. The ferromagnetic phase of \(\hbox {CdHo}_{2}\hbox {S}_{4}\) is energetically favourable compared to non-magnetic one, with a high magnetic moment of about 8.15 \(\upmu _{\mathrm{B}}\). The calculated band structure demonstrates that the title compound is a direct band gap semiconductor. The TB-mBJ yields a band gap of \(\sim \)1.86 and \(\sim \)2.17 eV for the minority and majority spins, respectively. The calculated optical spectra reveal a strong response in the energy range between the visible light and the extreme UV regions.     

Design of X‐band Moreno cross‐guide coupler based on superformula curves

This article deals with the design of Moreno cross‐guide couplers based on supershapes for X‐band applications. Crossed‐waveguide couplers are mainly used due to their compact structures. In these couplers, cross‐aperture structures are usually employed to offer flat coupling and high isolation. In the present article, the possible shapes for apertures and metal inserts that can be derived by the superfomula curves are explored and the effects of variations of superformula parameters are investigated on the performance of Moreno coupler. Finally, the proposed Moreno coupler is validated through fabrication and measurement. The experimental validation shows an excellent agreement with the simulated results. In the frequency range from 8 to 12.5 GHz, the measured coupling value changes from 18.8 to 20.8 dB and the directivity is better than 38 dB and 29 dB from 8 to 11 GHz and 11 to 12.5 GHz, respectively. The results are valuable for the design and evaluation of broadband high directive waveguide couplers.     

Using learning automata in brain emotional learning for speech emotion recognition

We propose an improved version of brain emotional learning (BEL) model trained via learning automata (LA) for speech emotion recognition. Inspiring from the limbic system in mammalian brain, the original BEL model is composed of two neural network components, namely amygdala and orbitofrontal cortex. In this modified BEL model, named brain emotional learning based on learning automata (BELBLA), we have employed the theory of the stochastic LA in error back-propagation to train the BEL model in decreasing the high computational complexity of the traditional gradient method. Hence, the performance of the model can be enhanced. For a speech emotion recognition task, we extract the usual features, such as energy, pitch, formants, amplitude, zero crossing rate and MFCC, from average short-term signals of the emotional Berlin dataset. The experimental results show that the BELBLA outperforms some opponents, like hidden Markov model, Gaussian mixture model, k-nearest neighbor, support vector machines and artificial neural networks, for this application.     

Synthesis of polyaniline based composite material and its analytical applications for the removal of highly toxic Hg<Superscript>2+</Superscript> metal ion: Antibacterial activity against <Emphasis Type="Italic">E. coli</Emphasis>

A composite material polyaniline-Zr(IV) phosphoborate (PZPB) was synthesized via sol-gel method by the combination of Zr(IV) phosphoborate and polyaniline. The PZPB composite material was characterized by various analytical techniques. The PZPB composite material was found to be selective for Hg²⁺+ metal ion due to the high distribution coefficient values for Hg²⁺+ metal ion in all mediums. The PZPB composite material was used for Hg²⁺+ removal under different experimental conditions. The antibacterial activity of PZPB composite material was also studied against E. coli.     

A probe into the status quo of interfacial adhesion in the compatibilized ternary blends with core/shell droplets: Selective versus dictated compatibilization

A simple approach was applied to probe into the situation of interfacial adhesion in the compatibilized ternary polymer blends with core/shell morphology. The performance of compatibilization was discussed in terms of thermal, rheological, and mechanical properties analyses for blends prepared through different mixing strategies for which maleic anhydride‐grafted high‐density polyethylene (HDPE‐g‐MAH) could be localized at the interface of HDPE/poly(ethylene‐co‐vinyl alcohol) copolymer (EVOH) or HDPE/polyamide 6 (PA‐6) in their ternary blends. Two mixing strategies, one simultaneously (one‐step or selective) and two sequentially (two‐step or dictated), were performed, compared, and discussed. It was found that mixing policy (dictated or selective) significantly changes the interfacial adhesion, as signaled by variations in rheological and thermal properties. In the case of mechanical properties, facilitation of stress transfer across the matrix/shell/core interfaces was detected by calculation of semi‐experimental models' coefficients. It was found that one‐step mixing or selective localization of HDPE‐g‐MAH helps in accumulation of more compatibilizer molecules at the interface HDPE/EVOH or EVOH/PA‐6. By contrast, addition of compatibilizer to minor phase (masterbatch of EVOH and PA‐6) or to HDPE matrix alone in case of two‐step blending causes imperfect stress transfer. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45503.     

Automating test oracles from restricted natural language agile requirements

Manual testing of software requirements written in natural language for agile or any other methodology requires more time and human resources. This leaves the testing process error prone and time consuming. For satisfied end users with bug‐free software delivered on time, there is a need to automate the test oracle process for natural language or informal requirements. The automation of the test oracle is relatively easier with formal requirements, but this task is difficult to achieve with natural language requirements. This study proposes an approach called Restricted Natural Language Agile Requirements Testing (ReNaLART) to automate the test oracle from restricted natural language agile requirements. For this purpose, it uses an existing user story template with some modifications for writing user stories. This helps in identifying test input and expected output for a user story. For comparison of expected and observed outputs it makes use of a regex pattern and string distance functions. It is capable of assigning different types of verdicts automatically depending upon the similarity/dissimilarity between observed and expected outputs of user stories. ReNaLART is validated using several case studies of different domains, namely, OLX Pakistan, Mental Health Tests, McDelivery Pakistan, BlueStacks, Power Searching with Google, TensorFlow Playground, w3Schools 2018 offline and Touch'D. It revealed several faults in five of the above listed eight applications. Plus, the proposed test oracle on an average took 0.02 s for test data generation, expected output generation and verdict assignment. Both these facts show the fault revealing effectiveness and efficiency of ReNaLART.