Event-triggered state estimation for Markovian jumping impulsive neural networks with interval time-varying delays

This paper investigates the event-triggered state estimation problem of Markovian jumping impulsive neural networks with interval time-varying delays. The purpose is to design a state estimator to estimate system states through available output measurements. In the neural networks, there are a set of modes, which are determined by Markov chain. A Markovian jumping time-delay impulsive neural networks model is employed to describe the event-triggered scheme and the network- related behaviour, such as transmission delay, data package dropout and disorder. The proposed event-triggered scheme is used to determine whether the sampled state information should be transmitted. The discrete delays are assumed to be time-varying and belong to a given interval, which means that the lower and upper bounds of interval time-varying delays are available. First, we design a state observer to estimate the neuron states. Second, based on a novel Lyapunov-Krasovskii functional (LKF) with triple-integral terms and using an improved inequality, several sufficient conditions are derived. The derived conditions are formulated in terms of a set of linear matrix inequalities , under which the estimation error system is globally asymptotically stable in the mean square sense. Finally, numerical examples are given to show the effectiveness and superiority of the results.     

Properties of pulse electrodeposited copper gallium sulphide films

Copper gallium sulphide films were deposited for the first time by the pulse electrodeposition technique at different duty cycles in the range of 6–50 % at room temperature and at a constant current density of 1.0 mA cm^?2. The films exhibited single phase copper gallium sulphide. The grain size increased from 30 to 70 nm with increase of duty cycle. Optical band gap of the films varied in the range of 2.30–2.36 eV. The resistivity increased from 0.10 to 1.70 ohm cm with increase of duty cycle from 6 to 50 %. Preliminary studies on solar cells with p-CuGaS₂/n-CuInS₂ junction yielded an efficiency of 4.14 %. This is the first report on solar cells using CuGaS₂ with CuInS₂.     

Rapid Microwave‐Assisted Solvothermal Synthesis of Methanol Tolerant Pt–Pd–Co Nanoalloy Electrocatalysts

We report here a microwave‐assisted solvothermal (MW‐ST) method to synthesise carbon‐supported multimetallic nanostructured alloys of Pt, Pd and Co with high crystallinity and homogeneity for electrocatalytic application in fuel cells. Multimetallic nanoalloy electrocatalysts have been synthesised by a one‐pot, rapid MW‐ST method within 15 min at <300 °C without any post‐annealing in reducing gas atmospheres. For a comparison, same multimetallic alloys were also synthesised by heat treatment of co‐precipitated metals. Significant differences were observed in the phase structure and surface composition of the alloys synthesised by the two methods, which were rationalised based on the synthesis procedures adopted. Further, the multimetallic alloys were also explored for their electrocatalytic applications as cathode catalysts for oxygen reduction reaction (ORR). The multimetallic alloys, synthesised by the MW‐ST method, show much higher ORR activity compared to their counterparts synthesised by the conventional borohydride reduction method. While the ORR activity of Pt₇₀Pd₂₀Co₁₀ is comparable to that of commercial Pt, the ORR activity of Pt₅₀Pd₃₀Co₂₀ in direct methanol fuel cells (DMFC) is superior to that of commercial Pt at high methanol concentrations due to its high tolerance to methanol that may crossover from the anode to the cathode.     

A co-catalyst free,eco-friendly,novel visible light absorbing iron based complex oxide nanocomposites for enhanced photocatalytic hydrogen evolution

This study exposes enhanced hydrogen evolution capability of Mg doped Calcium ferrite nanocomposite without any co-catalysts under natural sunlight irradiation. Structural studies of this chemically (sol-gel) synthesised nanocomposite revealed the co-existence of two or three complex oxide ferrites along with iron oxide phases. Optical studies confirmed its narrower bandgap suitable for visible light absorbance. Elemental analysis shows the presence and oxidation state of elements in all undoped and doped calcium ferrite photocatalysts. Hydrogen evolution rate of undoped and Mg doped Calcium ferrite calcined at three different temperatures is discussed. It was found that doping of Mg in calcium ferrite resulted in 19.6 times higher hydrogen evolution ratethan undoped calcium ferritedue to the co-operative assistance of each individual phase present in the nanocomposite.     

Preparation of nanocrystalline Mg4Nb2O9 by citrate gel method

A gel was formed when a aqueous solution of Mg(NO₃)₂, NbF₅ and citric acid in stoichiometric ratio was heated on a water bath. No precipitation was observed at acidic pH and gellation was complete with evaporation of the solvent. This gel on decomposition at 750°C produced nanocrystallites of ternary oxide, Mg₄Nb₂O₉ (M4N2). The phase contents and lattice parameters were studied by powder X-ray diffraction (XRD) at various temperatures. Particle size and morphology were studied by transmission electron spectroscopy (TEM). For comparison, M4N2 powders were also prepared by conventional ceramic route at 900°C.     

Multifiller nanocomposites containing gadolinium oxide and bismuth nanoparticles with enhanced X-ray attenuation property

We report here the development of multifiller nanocomposite containing gadolinium oxide and bismuth nanofillers with enhanced X-ray attenuation property. The mass attenuation coefficient of the nanocomposite is found to be 5.26 (X-ray attenuation: 95%) and 2.22 cm²/g (X-ray attenuation: 71%), respectively, under dental and lung X-ray scan conditions. Fourier transform infrared spectroscopy confirms the interfacial interaction between Gd₂O₃ nanofillers and the polymer matrix through hydrogen bonding. Atomic force microscopy images of the nanocomposite show a smooth and uniform topography with an average surface roughness of ~19 nm. Thermogravimetric analysis confirms the thermal stability of the nanocomposite upto 384°C. The enhanced X-ray attenuation property of the nanocomposite is attributed to the good interfacial bonding, dual k-edge effect of nanofillers and their uniform distribution within the polymeric matrix. Therefore, this nanocomposite is a promising material for diagnostic X-ray shielding, especially as, thyroid collar, gonad shield, aprons, gloves, and so on.     

Antioxidant and antidiabetic properties of condensed tannins in acetonic extract of selected raw and processed indigenous food ingredients from Kenya

Recently, tannins have received considerable attention as health-promoting component in various plant foods and several studies have reported on its nutraceutical properties. However, no study has established the role of condensed tannins in indigenous foods of Kenya. Therefore, this study was designed to evaluate the antioxidant activity (DPPH and FRAP) and antidiabetic effects (α-amylase and α-glucosidase inhibition activities) of condensed tannins in some selected raw and traditionally processed indigenous cereals, legumes, oil seeds, and vegetables. The condensed tannin content of the grains and vegetables ranged between 2.55 and 4.35 g/100 g DM and 1.53 and 5.73 g/100 g DM, respectively. The scavenging effect of acetonic extract on DPPH radical ranged from 77% to 90% while the reducing power was found to be 31 to 574 mmol Fe(II)/g DM in all the investigated food ingredients. The condensed tannin extracts of the analyzed samples showed promising antidiabetic effects with potential α-amylase and α-glucosidase inhibition activities of 23% to 44% and 58% to 88%, respectively. Condensed tannins extracted from the amaranth grain, finger millet, field bean, sunflower seeds, drumstick, and amaranth leaves exerted significantly higher antioxidant and antidiabetic activities than other food ingredients. Among the traditional processing methods, roasting of grains and cooking of vegetables were found to be more suitable mild treatments for preserving the tannin compound and its functional properties as opposed to soaking + cooking and blanching treatments. The identified elite sources of optimally processed indigenous food ingredients with promising results could be used as health-promoting ingredients through formulation of therapeutic diets.     

The nutritional and antinutritional attributes of sword bean [Canavalia gladiata (Jacq.) DC.]: an under-utilized tribal pulse from south India

Six accessions [three with maroon‐coloured seed coat and three with white‐coloured seed coat) of sword bean (Canavalia gladiata (Jacq.) DC.], were collected from six different locations in south India. They were analysed for their proximate and mineral composition, amino acid profiles of total seed proteins, in vitro protein digestibility (IVPD) and certain antinutritional factors. The essential amino acid profile of total seed proteins compared favourably with FAO/WHO requirements, except that there were deficiencies of sulphur containing amino acids in all the six accessions and also the leucine, lysine and tryptophan contents were low in maroon‐coloured seed coat accessions. The IVPD of the accessions ranged from 63.39 to 76.92%. Antinutritional substances like total free phenolics, tannins, l ‐DOPA (3,4‐dihydroxyphenylalanine), trypsin inhibitor activity and phytohaemagglutinating activity were also investigated. The antinutritional factors that were detected were thought to have little nutritional significance if the beans are properly processed.