Synthesis,defect characterization and photocatalytic degradation efficiency of Tb doped CuO nanoparticles

Monoclinic undoped and Tb doped CuO are prepared by solution combustion method and annealed at different temperatures. The effect of annealing and doping on their structural and optical properties of CuO are examined using XRD, FTIR and DRS. The surface and lattice defects in CuO and Tb doped CuO is analyzed qualitatively and quantitatively using positron lifetime and Doppler broadening spectroscopy. The average positron lifetime and electron momentum (energy) S parameter increases owing to the number of vacancies in the CuO lattice upon doping and decreases with increasing temperature. The migration of vacancies from grain to grain boundary region is observed at 600 °C annealed samples. At 800 °C, the overall behavior of lifetime value denotes that the vacancy type defect is recovered, cluster vacancy and microvoids exists with reducing size. The photocatalytic performance of undoped and Tb doped CuO on degradation of methylene blue (MB) and methyl orange (MO) is investigated under visible light for two different lamp power and dye concentration. The influence of annealing temperature and dopant ion on the efficiency is also elaborated. Enhanced photocatalytic efficiency in Tb doped CuO is observed upon annealing. X-ray photoelectron spectroscopy (XPS) result indicates that the valence states of Cu, O and Tb ions exist at the surface of the particles. Brunauer–Emmett–Teller N₂ adsorption–desorption analyses were employed to characterize specific surface area and porosity of Tb doped CuO. The doped CuO with pore size of about ～34 nm have a surface area of 16–28 m²/g. The surface area effect plays an important role in the enhanced catalytic performance on Tb doped catalysts.     

A comparative study of 3E (energy,exergy, and economy) analysis of various solar stills

In this paper, an experimental study of the conventional solar still (CSS), the conventional solar still with glass cooling (CSSGC), the conventional solar still with basin heating (CSSBH), and the conventional solar still with glass cooling and basin heating (CSSGCBH) was carried out on the basis of the distilled water production, the energy efficiency (EnE), the exergy efficiency (ExE), and economic analysis. The CSSGC and CSSBH contain Peltier modules for cooling the glass and heating the basin. The evaporative heat transfer coefficient for all the experimental stills was calculated. The values of daily distilled water production from the CSSGCBH, CSSBH, CSSGC, and CSS were 4.56, 3.79, 2.49, and 1.89 kg/m², respectively. The daily distilled yield of the CSSBH and CSSGCBH were increased by 58.55% and 50.13%, respectively, as compared with the CSS. Moreover, the daily EnE and ExE of the CSSGCBH were 27.03% and 3.5%, respectively, whereas the EnE and ExE of the CSS were 10.88% and 1.3%, respectively. Furthermore, the cost of distilled water production was found to be 0.26, 0.35, 0.53, and 0.64 $/day for the CSS, CSSGC, CSSBH, and CSSGCBH, respectively, if the selling price of the distilled water was Rs10.     

CORROSION INHIBITION OF CARBON STEEL IN LOW CHLORIDE MEDIA BY AN AQUEOUS EXTRACT OF HIBISCUS ROSA-SINENSIS LINN

The inhibition efficiency (IE) of an aqueous extract of white flower, namely, Hibiscus rosa-sinensis Linn., in controlling corrosion of carbon steel immersed in an aqueous solution containing 60 ppm of Cl^-has been evaluated by the mass loss method. The flower extract (FE) shows good IE. In the presence of Zn²⁺, excellent IE is shown by the flower extract. A synergistic effect exists between the flower extract and Zn²⁺. The mechanistic aspects of corrosion inhibition have been investigated by polarization study and AC impedance spectra. Polarization study reveals that the formulation consisting of flower extract and Zn²⁺ functions as a mixed inhibitor. AC impedance spectra reveal that a protective film is formed on the metal surface. The active principle in the flower extract is quercetin-3-O-glucoside. This has been confirmed by UV-visible absorption spectra. The protective film formed on the metal surface has been analyzed by FT-IR and AFM spectra. It is found that the protective film consists of Fe²⁺-quercetin-3-O-glucoside complex and Zn(OH)₂.     

Biosorption of cadmium (II) and lead (II) from aqueous solutions using mushrooms: A comparative study

Sorption capacity of oyster mushroom (Pleurotus platypus), button mushroom (Agaricus bisporus) and milky mushroom (Calocybe indica) were evaluated on biosorption of heavy metals, viz. cadmium (II) and lead (II) from aqueous solutions. The optimum sorption conditions were studied for each metal separately. The desired pH of the aqueous solution was found to be 6.0 for the removal of cadmium (II) and 5.0 for removal of lead (II) for all the mushrooms. The percent removal of both the metals was found to increase with the increase in biosorbent dosage and contact time. The fitness of the biosorption data for Langmuir and Freundlich adsorption models was investigated. It was found that biosorption of cadmium (II) and lead (II) ions onto the biomass of the three mushrooms were better suitable to Langmuir than Freundlich adsorption model. P. platypus showed the highest metal uptake potential for cadmium (q_max 34.96 mg/g) whereas A. bisporus exhibited maximum potential for lead (q_max 33.78 mg/g). Milky mushroom showed the lowest metal uptake capacity for both the metals. The present data confirms that mushrooms may be used as efficient biosorbent for the removal of cadmium (II) and lead (II) ions from aqueous solution.     

An automatic non-English sentiment lexicon builder using unannotated corpus

The Journal of Supercomputing - Sentiment lexicons in the English language are widely accessible while in many other languages, these resources are extremely deficient. Current techniques and...     

Mobile Technology in the Classroom: What Drives Student-Lecturer Interactions?

Online learning when combined with mobile technology transforms the traditional classrooms from teacher-centered to student-centered classrooms. Despite the widespread use of mobile technology among students and educators today, limited researches have been conducted to study the effects of using mobile technology to enhance student–lecturer interactions. In addition, existing theories of technology acceptances, chiefly Information System Success Model (ISSM), Motivational Model (MM), Social Cognitive Theory (SCT), Technology Acceptance Model (TAM), and Cultural Dimension Theory (CDT) are widely recognized for their predictive power in determining adoption intentions. In this study, determinants from all five theories were unified and examined, namely system quality and information quality from ISSM, enjoyment from MM, perceived usefulness and perceived ease of use from TAM, self-efficacy from SCT, and uncertainty avoidance from CDT as predictors of adoption intention in the context of predicting student–lecturer interactions. This empirical study was conducted using an online survey. Data collected from the samples (n = 328) were analyzed using PLS-SEM. Results obtained exhibited adequate explanatory power, where information quality, system quality, enjoyment, and uncertainty avoidance significantly predict adoption intention, while perceived usefulness, perceived ease of use, and self-efficacy were insignificant. Secondly, each theory was independently analyzed, and the predictive power and relevance of ISSM, MM, TAM, and UDT confirmed the importance and relevance of these theories. Results obtained provided a comprehensive understanding of the factors that significantly affect students’ intentions to use mobile technology to interact with their lecturers on academic matters. The discussions and implications of this study are crucial for researchers and practitioners of educational technologies in higher education.     

Smile intensity recognition in real time videos: fuzzy system approach

Multimedia Tools and Applications - Facial emotion is a significant way of understanding or interpreting one’s inner thoughts. Real time video at any instant exhibits the emotion which serves...     

Inhibition of calcium phosphate precipitation under environmentally-relevant conditions

Precipitation of Ca phosphates plays an important role in controlling P activity and availability in environmental systems. The purpose of this study was to determine inhibitory effects on Ca phosphate precipitation by Mg(2+), SO(4)(2-), CO(3)(2-), humic acid, oxalic acid, biogenic Si, and Si-rich soil clay commonly found in soils, sediments, and waste streams. Precipitation rates were determined by measuring decrease of P concentration in solutions during the first 60 min; and precipitated solid phases identified using X-ray diffraction and electron microscopy. Poorly-crystalline hydroxyapatite (HAP: Ca(5)(PO(4))(3)OH) formed in control solutions over the experiment period of 24 h, following a second-order dependence on P concentration. Humic acid and Mg(2+) significantly inhibited formation of HAP, allowing formation of a more soluble amorphous Ca phosphate phase (ACP), and thus reducing the precipitation rate constants by 94-96%. Inhibition caused by Mg(2+) results from its incorporation into Ca phosphate precipitates, preventing formation of a well-crystalline phase. Humic acid likely suppressed Ca phosphate precipitation by adsorbing onto the newly-formed nuclei. Presence of oxalic acid resulted in almost complete inhibition of HAP precipitation due to preemptive Ca-oxalate formation. Carbonate substituted for phosphate, decreasing the crystallinity of HAP and thus reducing precipitation rate constant by 44%. Sulfate and Si-rich solids had less impact on formation of HAP; while they reduced precipitation in the early stage, they did not differ from the control after 24 h. Results indicate that components (e.g., Mg(2+), humic acid) producing relatively soluble ACP are more likely to reduce P stability and precipitation rate of Ca phosphate in soils and sediments than are components (e.g., SO(4)(2-), Si) that have less effect on the crystallinity.