Synthesis and morphological control of europium doped cadmium sulphide nanocrystals

Europium doped cadmium sulphide (Cd(0.98)Eu(0.2)S) nanostructures were synthesised by chemical co-precipitation method using ethylene glycol (EG) and deionized water (Eu:CdS-1), and isopropyl alcohol (IPA) and deionized water (Eu:CdS-2) as mixed solvents. It has been found that the nanostructure of the europium doped CdS can be controlled by simply varying the mixed solvent system. Powder XRD pattern reveals the formation of hexagonal (wurtzite) and cubic (zinc blende) structure for Eu:CdS-1, and Eu:CdS-2, respectively. The crystallite size of the sample prepared using IPA and deionized water was measured to be 2.64 nm which is much smaller than that of the sample prepared using EG and deionized water as mixed solvent (3.65 nm). Morphology of the materials can also be changed from flower shaped crystals to paddy like structures by varying the mixed solvents. Band gap values of Eu3+ doped CdS nanocrystals synthesized from two different solvents were estimated using UV-reflectance spectra. The size and crystallinity of the samples were confirmed by HRTEM and SAED analysis. A significant change in the PL emission of the CdS nanocrystals was observed for the europium doped CdS which is mainly due to the presence of EU3+ ions which also play a significant role in the energy transfer process. It was also observed that the shift in the emission and efficiency depends on size and shape of the synthesised nanoparticles.     

Optimization of Process Parameters for Decortication of Finger Millet Through Response Surface Methodology

Decorticated finger millet is prepared by hardening the endosperm by hydrothermal processing and polishing the processed grains. The yield of the decorticated grains is of paramount importance in the millet industry. Milling yield depends on the grain moisture content and incipient moisture conditioning during milling. It was found that steaming conditions such as steaming time and steam pressure significantly influenced the milling yield. Hence, studies were undertaken to determine the influence of moisture and steaming conditions on the yield of decorticated millet. Steaming conditions were optimized through response surface methodology. The responses studied were hardness, milling yield, porosity and water uptake of hydrothermally processed millet. The studies indicated that hydrothermally processed millet with 16±1% moisture content, tempered with 5% added water at I stage and 4% water in the II stage milling, resulted in a yield of 64.6%. The relationship of milling yield, hardness and porosity of the millet was quadratic with the severity of steaming conditions, while water uptake of the steamed millet exhibited a linear relationship. Based on the regression analysis, optimum conditions estimated for steaming time and pressure were 17.5 min and 313.8 kPa, respectively. At this condition, the milling yield, water uptake, porosity and hardness values were also predicted and the values were 68.33 g/100 g, 63.43 g/100 g, 52.23% and 204.01 N, respectively. The studies indicate that steaming the millet at elevated pressure and temperature increases the milling yield and steaming beyond the threshold level has a detrimental effect on the yield of head grains.     

A Comparative Assessment of Nutritional Composition,Total Phenolic,Total Flavonoid,Antioxidant Capacity,and Antioxidant Vitamins of Two Types of Malaysian Underutilized Fruits (Averrhoa Bilimbi and Averrhoa Carambola)

Nutritional composition, total phenolic content, total flavonoid, antioxidant capacity, and antioxidant vitamins of bilimbi (Averrhoa bilimbi) and carambola (Averrhoa carambola) were determined and compared in this study. Bilimbi was found to contain higher moisture, ash, carbohydrate, protein, fat, and dietary fiber compared to carambola. Total phenolic content was higher in carambola although bilimbi yielded more total flavonoid. Vitamins A, C, and E contents of bilimbi were also higher than carambola. Antioxidant and scavenging activity as determined by β-carotene bleaching assay and DPPH radical scavenging assay of carambola were significantly (p < 0.05) higher than bilimbi. These results suggested that carambola was a potent natural antioxidant food and that contribution of phenolic compounds to its antioxidant capacity was greater than that of antioxidant vitamins.     

Effect of KCl on the bulk growth KDP crystals by Sankaranarayanan-Ramasamy method

The effect of the addition of potassium chloride (KCl) in bulk growth unidirectional 〈0 0 1〉 potassium dihydrogen phosphate (KDP) grown from aqueous solution by Sankaranarayanan-Ramasamy (SR) method has been studied. The crystal of 15 mm diameter, 95 mm height was grown by SR method. Addition of 5 M% KCl in the bulk growth medium increases the quality as well as the growth rate. The grown crystals were characterized by UV–Vis spectroscopy, microhardness and dielectric studies. It reveals that the SR method grown crystalline quality and perfection is better than the conventional method grown crystal.     

Highly basic CaO nanoparticles in mesoporous carbon materials and their excellent catalytic activity

Highly basic CaO nanoparticles immobilized mesoporous carbon materials (CaO-CMK-3) with different pore diameters have been successfully prepared by using wet-impregnation method. The prepared materials were subjected to extensive characterization studies using sophisticated techniques such as XRD, nitrogen adsorption, HRSEM-EDX, HRTEM and temperature programmed desorption of CO2 (TPD of CO2). The physico-chemical characterization results revealed that these materials possess highly dispersed CaO nanoparticles, excellent nanopores with well-ordered structure, high specific surface area, large specific pore volume, pore diameter and very high basicity. We have also demonstrated that the basicity of the CaO-CMK-3 samples can be controlled by simply varying the amount of CaO loading and pore diameter of the carbon support. The basic catalytic performance of the samples was investigated in the base-catalyzed transesterification of ethylacetoacetate by aryl, aliphatic and cyclic primary alcohols. CMK-3 catalyst with higher CaO loading and larger pore diameter was found to be highly active with higher conversion within a very short reaction time. The activity of 30% CaO-CMK3-150 catalyst for transesterification of ethylacetoacetate using different alcohols increases in the following order: octanol > butanol > cyclohexanol > benzyl alcohol > furfuryl alcohol.     

Correlating Molecular Structure to the Behavior of Linear Styrene–Butadiene Viscosity Modifiers

The effect of linear styrene–butadiene polymer structure on the temperature–viscosity behavior of model polymer-base oil solutions is investigated using molecular dynamics simulations. Simulations of alternating, random, and block styrene–butadiene polymers in a dodecane solvent are used to calculate viscosity at 40 and 100 °C, reference temperatures for characterizing their function as viscosity modifiers. Mechanisms underlying this function are explored by quantifying the radius of gyration and intramolecular interactions of the polymers at the same reference temperatures. The block styrene–butadiene configuration exhibits the least change in viscosity with temperature, characteristic of a good viscosity modifier or viscosity index improver, and the behavior is correlated to the ability of this structure to form smaller coils with more intramolecular interactions at lower temperatures and then expand as temperature is increased. The results indicate that there is a correlation between styrene–butadiene polymer structure, additive function, and the mechanisms underlying that function.     

Effect of temperature on the ozonation of textile waste effluent

Ozonation in batch experiments were conducted at elevated temperatures to study the influence of temperature on the efficiency of ozonation. The effect of temperature on ozonation was determined by measuring the extent of colour removal and the reduction of chemical oxygen demand (COD) and total organic carbon (TOC) of a textile waste effluent. It was found that increasing the temperature causes a decrease in the levels of colour, COD and TOC. Complete mineralisation of the dye molecule, however, did not occur to an appreciable extent. The efficiency of colour removal was 71.3%, whilst the COD and TOC reduction efficiency was 20.3 and 19.3%, respectively, at the highest temperature studied (50 °C). The removal efficiency of COD, however, did not improve significantly when the temperature was increased from 40 to 50 °C.     

Computational Modelling on Heat Transfer Study of Molten Silicon During Multi-crystalline Silicon Growth Process for PV Applications

Multi-crystalline silicon is an important material with advantages of low-production cost and high conversion efficiency for photovoltaic solar cells. Directional solidifi cation has become the main technique for producing mc-Si ingots for solar cell applications. The study is performed in the framework of the incompressible Navier-Stokes equation in the Boussinesq approximation with convection-conduction equations. The computations are carried out in a two dimensional (2D) axisymmetric model by the finite- element method. The influence of the Reynolds numbers, total heat flux and velocity streamline pattern on the silicon melt was simulated and analyzed for various Rayleigh numbers between 10 to 10 ⁶ with the help of a numerical technique. The following key findings are presented in this paper. The velocity field value is increased above 0.02(m/s), heat flux value is increased to 10 ⁴(W/m ²), when the Rayleigh number is increased above 1000. Reynolds numbers are also studied in five parallel horizontal cross-sections of the melt silicon region for various Prandtl numbers at a critical Rayleigh number of 1000. Reynolds numbers are varied between 100 and 10 ⁵ for the Rayleigh numbers between 10 to 10 ⁶. Meanwhile, the melt has high fluctuation when the Prandtl number is increased above 0.01. The flow is converted from laminar to turbulence at a critical Rayleigh number 1000 and Prandtl number 0.01. These results provide important information for controlling the melt fluctuations during the solidification process which are used to increase the average grain size in growing silicon multicrystals and reduce the dislocation density.     

Effective solution for unhandled exception in decision tree induction algorithms

This paper deals with some improvements to rule induction algorithms in order to resolve the tie that appear in special cases during the rule generation procedure for specific training data sets. These improvements are demonstrated by experimental results on various data sets. The tie occurs in decision tree induction algorithm when the class prediction at a leaf node cannot be determined by majority voting. When there is a conflict in the leaf node, we need to find the source and the solution to the problem. In this paper, we propose to calculate the Influence factor for each attribute and an update procedure to the decision tree has been suggested to deal with the problem and provide subsequent rectification steps.     

Interface Oxygen Vacancy-Enhanced Co3O4/WO3 Nanorod Heterojunction for Sub-ppm Level Detection of NOx

Herein, a cobalt oxide/tungsten oxide (Co₃O₄/WO₃) p–n heterojunction for NO_x detection is developed and optimized. Field-emission scanning electron microscopy shows that the WO₃ nanorods are embellished with Co₃O₄ nanostructure. X-ray photoelectron spectroscopy reveals the presence of oxygen vacancy on the Co₃O₄ coupled with WO₃ heterojunction. Compared to bare WO₃ and pure Co₃O₄, the Co₃O₄/WO₃ heterojunction sensor shows significant sensitivity to NO_x at 200 °C. The sensor exhibits higher linearity from 0.4 to 10 ppm of NO_x, with a sensing response of 4.4–93%. The NO_x sensitivity of the Co₃O₄/WO₃ heterojunction sensor is ninefold higher than that of the pure WO₃ sensor. Even in a high humidity (84%) environment, the Co₃O₄/WO₃ heterojunction sensor demonstrates high NO_x sensitivity. The sensor maintains remarkable stability measured for up to 4 weeks. The possible NO_x sensing mechanism of the Co₃O₄/WO₃ heterojunction is additionally discussed.