Photovoltaic performance of TiO<Subscript>2</Subscript> using natural sensitizer extracted from <Emphasis Type="Italic">Phyllanthus Reticulatus</Emphasis>

Phyllanthus reticulatus, a natural sensitizer has been extracted from Karunelli fruit for the fabrication of TiO₂ based DSSCs. The extracted dye shows the visible light optical absorption at a wavelength of around 520 nm. The presence of anthocyanin in the dye extract has been identified by the functional molecular groups such as intermolecular –OH bond, conjugate C=O stretching vibrations using FTIR. A commercial P25 TiO₂ anatase powder has been employed for the fabrication of photoanode on fluorine doped tin oxide (FTO) substrate using Doctor-blade technique. The Platinum (Pt) counter electrode has been prepared using electron beam evaporation technique with a thickness of ~200 nm. To measure the photoconversion efficiency of the stacked DSSCs, the electrodes are assembled into a cell module and illuminated by a light source simulating AM 1.5 with a light intensity of 100 mW/cm². The freshly prepared sensitizer (P. reticulatus pH ~5.5) exhibits the photo-conversion efficiency of 0.19%, while decreasing the pH of the sensitizer (pH ~1.0) enhances the photoconversion efficiency to six times (0.69%) higher than that of fresh one.     

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.     

Binding of Citrate-Fe3+ to Plastic Culture Dishes,an Artefact Useful as a Simple Technique to Screen for New Iron Chelators

NaCT mediates citrate uptake in the liver cell line HepG2. When these cells were exposed to iron (Fe³⁺), citrate uptake/binding as monitored by the association of [¹⁴C]-citrate with cells increased. However, there was no change in NaCT expression and function, indicating that NaCT was not responsible for this Fe³⁺-induced citrate uptake/binding. Interestingly however, the process exhibited substrate selectivity and saturability as if the process was mediated by a transporter. Notwithstanding these features, subsequent studies demonstrated that the iron-induced citrate uptake/binding did not involve citrate entry into cells; instead, the increase was due to the formation of citrate-Fe³⁺ chelate that adsorbed to the cell surface. Surprisingly, the same phenomenon was observed in culture wells without HepG2 cells, indicating the adsorption of the citrate-Fe³⁺ chelate to the plastic surface of culture wells. We used this interesting phenomenon as a simple screening technique for new iron chelators with the logic that if another iron chelator is present in the assay system, it would compete with citrate for binding to Fe³⁺ and prevent the formation and adsorption of citrate-Fe³⁺ to the culture well. This technique was validated with the known iron chelators deferiprone and deferoxamine, and with the bacterial siderophore 2,3-dihydroxybenzoic acid and the catechol carbidopa.     

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.