Photovoltaic performance of dye-sensitized solar cells fabricated with polyvinylidene fluoride–polyacrylonitrile–silicondioxide hybrid composite membrane

Electrospun fibrous membranes of hybrid composites of polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN) and silicon dioxide (SiO₂) (PVdF–PAN–SiO₂) are prepared with different proportions of SiO₂ (3, 5 and 7% w/w). The field emission scanning electron microscopy (FE-SEM) reveals that these membranes have three-dimensional, fully interconnected network structures, which are combined with micropores of fine SiO₂ distribution. The surface roughness of the membranes increases with increasing the SiO₂ content. It is found that 7 wt% SiO₂/PVdF–PAN electrolyte membrane has the highest ionic conductivity (6.96 × 10⁻² S cm⁻¹) due to the large liquid electrolyte uptake (about 570%). As the concentration of SiO₂ nanoparticles increase, the contact angle value also increases, ranging from 135.70° to 140.60° which indicates that the membrane has higher hydrophobicity. The dye sensitized solar cells (DSSCs) are fabricated using the hybrid composite membrane with PVdF–PAN with 7 wt % SiO₂. Its photovoltaic performance exhibits an open circuit voltage (V_oc) of 0.79 V and a short circuit current 11.6 mA cm⁻² at an incident light intensity of 100 mW cm⁻², producing an efficiency of 5.61%. DSSC, using the hybrid composite electrospun membrane which shows more stable photovoltaic performance than other assembled DSSCs.     

Prediction of cutting force based on machining parameters on AL7075-T6 aluminum alloy by response surface methodology in end milling

Cutting forces modeling is the basic to understand the cutting process, which should be kept in minimum to reduce tool deflection, vibration, tool wear and optimize the process parameters in order to obtain a high quality product within minimum machining time. In this paper a statistical model has been developed to predict cutting force in terms of geometrical parameters such as rake angle, nose radius of cutting tool and machining parameters such as cutting speed, cutting feed and axial depth of cut. Response surface methodology experimental design was employed for conducting experiments. The work piece material is Aluminum (Al 7075-T6) and the tool used is high speed steel end mill cutter with different tool geometry. The cutting forces are measured using three axis milling tool dynamometer. The second order mathematical model in terms of machining parameters is developed for predicting cutting forces. The adequacy of the model is checked by employing ANOVA. The direct effect of the process parameter with cutting forces are analyzed, which helps to select process parameter in order to keep cutting forces minimum, which ensures the stability of end milling process. The study observed that feed rate has the highest statistical and physical influence on cutting force.     

Cellulose acetate and sulfonated polysulfone blend ultrafiltration membranes. I. Preparation and characterization

Modification of polymeric membrane materials by incorporation of hydrophilicity results in membranes with low fouling behavior and high flux. Hence, Polysulfone was functionalized by sulfonation and ultrafiltration membranes were prepared based on sulfonated polysulfone and cellulose acetate in various blend compositions. Polyethyleneglycol 600 was employed as a nonsolvent additive in various concentrations to the casting solution to improve the ultrafiltration performance of the resulting membranes. The total polymer concentration, cellulose acetate, and sulfonated polysulfone polymer blend composition, additive concentration, and its compatibility with polymer blends were optimized. The membranes prepared were characterized in terms of compaction, pure water flux, membrane resistance, and water content. The compaction takes place within 3–4 h for all the membranes. The pure water flux is determined largely by the composition of sulfonated polysulfone and concentration of additive. Membrane resistance is inversely proportional to pure water flux, and water content is proportional to pure water flux for all the membranes. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1749–1761, 2002     

Polyelectrolyte and silver nanoparticle modification of microfiltration membranes to mitigate organic and bacterial fouling

Membrane fouling remains one of the most problematic issues surrounding membrane use in water and wastewater treatment applications. Organic and biological fouling contribute to irreversible fouling and flux decline in these processes. The aim of this study was to reduce both organic and biological fouling by modifying the surface of commercially available poly(ether sulfone) (PES) membranes using the polyelectrolyte multilayer modification method with poly(styrenesulfonate) (PSS), poly(diallyldimethylammonium chloride) (PDADMAC), and silver nanoparticles (nanoAg) integrated onto the surface as stable, thin (15 nm) films. PSS increases the hydrophilicity of the membrane and increases the negative surface charge, while integration of nanoAg into the top PSS layer imparts biocidal characteristics to the modified surface. Fouling was simulated by filtering aqueous solutions of humic acid (5 and 20 mg L(-1)), a suspension of Escherichia coli (10(6) colony-forming units (CFU) mL(-1)), and a mixture of both foulants through unmodified and modified PES membranes under batch conditions. Filtration and cleaning studies confirmed that the modification significantly reduced organic and biological fouling.     

Green synthesis of copper oxide nanoparticles and mosquito larvicidal activity against dengue,zika and chikungunya causing vector Aedes aegypti

In the present study, high purity copper oxide nanoparticles (NPs) were synthesised using Tridax procumbens leaf extract. Green syntheses of nano‐mosquitocides rely on plant compounds as reducing and stabilising agents. Copper oxide NPs were characterised using X‐ray diffraction (XRD) analysis, Fourier transform infrared (FT‐IR), Field‐emission scanning electron microscopy with energy dispersive spectroscopy, Ultraviolet–visible spectrophotometry and fluorescence spectroscopy. XRD studies of the NPs indicate crystalline nature which was perfectly matching with a monoclinic structure of bulk CuO with an average crystallite size of 16 nm. Formation of copper oxide NPs was confirmed by FT‐IR studies and photoluminescence spectra with emission peaks at 331, 411 and 433 nm were assigned to a near‐band‐edge emission band of CuO in the UV, violet and blue region. Gas chromatography–mass spectrometry studies inferred the phytochemical constituents of the leaf extract. Larvicidal activity of synthesised NPs using T. procumbens leaf extract was tested against Aedes aegypti species (dengue, chikungunya, zika and yellow fever transmit vector).Inspec keywords: photoluminescence, spectrophotometry, thermal analysis, chromatography, nanoparticles, antibacterial activity, field emission electron microscopy, microorganisms, wide band gap semiconductors, scanning electron microscopy, X‐ray diffraction, copper compounds, ultraviolet spectra, nanofabrication, X‐ray chemical analysis, crystallites, visible spectra, field emission scanning electron microscopy, nanobiotechnology, semiconductor materials, semiconductor growth, fluorescence, mass spectraOther keywords: energy dispersive spectroscopy, ultraviolet–visual spectrophotometry, fluorescence spectroscopy, chikungunya, green synthesis, mosquito larvicidal activity, zika, X‐ray diffraction analysis, field‐emission scanning electron microscopy, XRD, gas chromatography–mass spectrometry, copper oxide nanoparticles, dengue, tridax procumben leaf extract, nanomosquitocides, FTIR, monoclinic structure, crystallite size, photoluminescence spectra, near‐band‐edge emission band, phytochemical constituents, Aedes aegypti species, yellow fever transmit vector, CuO     

Design and Development of Dipole Array Antenna for Wi-Fi Applications

Wireless Personal Communications - This paper illustrates the design and development of the series-fed two-dipole-array antenna (STDA) for Wi-Fi applications. The proposed antenna consists of two...     

Evaluation of biohydrogen production potential of fragmented sugar industry biosludge using ultrasonication coupled with egtazic acid

In this study, the influence of ultrasonication (USN) combined with egtazic acid fragmentation method on sugar industry waste (SWS) sludge was studied for improving biohydrogen production. Initially, USN method was proceeded by varying power and fragmentation time. At an optimal power (115 W) and fragmentation time (30 min), USN method demanded 23,000 kJ/kg TS specific energy for achieving 15.2% complex organics solubilization rate (COR). To further upsurge of SWS sludge solubilization, USN assisted with egtazic acid (USNEG) method was performed by varying fragmentation time and egtazic acid dosage at an optimal power (115 W). USNEG method has achieved more COR (23%) at minimum specific energy of 11,500 kJ/kg TS (fragmentation time: 15 min and EGTA dosage: 0.03 g/g TS). Then, biohydrogen potential (BHP) assay was investigated in which USNEG method has obtained higher biohydrogen production. Also, energy analysis revealed that USNEG method exhibited an energy ratio of 1.78.     

Study on optimization of co-digestion process parameters for enhancing biohydrogen production using response surface methodology

In the present study, batch anaerobic co-digestion experiment was conducted with dairy secondary clarifier waste activated sludge as substrate and anaerobic digested municipal waste activated sludge as seed sludge for enhancing biohydrogen rate. The statistical tools were used to study the effect of co-digestion process parameters (pH, seed sludge, temperature, and digestion time) on mixed liquor suspended soils (MLSS) reduction % and chemical oxygen demand (COD) solubilization %. The maximum of MLSS reduction and COD solubilization obtained at global optimal condition (pH 6, temperature 40°C, seed sludge 35 ml, and digestion time 30 days) determined, respectively, were 22.7 and 28.02%. Subsequently, the production data of cumulative biohydrogen were fitted with modified Gompertz equation and the biohydrogen kinetic parameters were determined.     

Physical,sensory, in-vitro starch digestibility and glycaemic index of granola bars prepared using sucrose alternatives

Granola bars were prepared using barley flakes, groundnut bits, cocoa powder, sucrose and/or sucrose alternatives (coconut sugar, fructooligosaccharide and inulin). Apart from sensory acceptance, nutritional composition, energy values and glycaemic responses (glycaemic index, GI and glycaemic load, GL) of the bars were evaluated. Physico-chemical properties and sensorial acceptance of granola bar made with coconut sugar and fructooligosaccharide were on par with those made with sucrose. Further, all formulated granola bars, except with inulin, were intermediate moisture foods. GI of all five formulations of granola bars was <55; ranging between 51 and 54.9, corresponding to low glycaemic food. Granola bars with coconut sugar had high GL (≥20), while bars prepared with FOS, inulin and without sugar were in the medium range (>10 to <20). Effect of choice of raw materials, complexity of matrix structure and particle size of ingredients on GI and GL of the bars is explained.