Synthesis and systematic investigations of Al and Cu-doped ZnO nanoparticles and its structural,optical and photo-catalytic properties

Here we report, copper (Cu) and Aluminum (Al) doped zinc oxide (ZnO) nanoparticles by a novel one step microwave irradiation method for the first time. Powder X-ray diffraction (XRD) reveals that both pure and doped samples assigned to hexagonal wurtzite type structure. The calculated average crystalline size decreases from 24 to 11 nm for pure and doped (Al and Cu) ZnO respectively, which is in good agreement with the particles size observed from Transmission Electron Microscope (TEM) analyses. A considerable red shift in the absorption edge and the reduction in the energy gap from 3.35 to 2.95 eV reveal the substitution of Al³⁺ and Cu²⁺ ions into the ZnO lattice analyzed by UV–Vis transmission spectra. The photocatalytic degradation of Methyl Violet (MV), Phenol and Rhodamine B (RHB) was investigated by using pure, Al and Cu doped ZnO catalyst under UV light irradiation. The results showed that the photocatalytic property is significantly improved by Cu doping concentration. This could be attributed to extended visible light absorption, inhibition of the electronehole pair’s recombination and enhanced adsorptivity of dye molecule on the surface of Cu–ZnO nanopowders. The samples were further characterized by photoluminescence spectra and Fourier Infrared Spectra (FTIR) analysis.     

Priority scheduling with consolidation based backfilling algorithm in cloud

In cloud computing, scheduling plays an eminent role while processing enormous jobs. The paralle jobs utmost need parallel processing capabilities which leads to CPU underutilization mainly due to synchronization and communication among parallel processes. Researchers introduced several algorithms for scheduleing parallel jobs namely, Conservative Migration Consolidation supported Backfilling (CMCBF) and Aggressive Migration Consolidation supported Backfilling (AMCBF). The greatest challenge of a existing scheduling algorithm is to improve the data center utilization without affecting job responsiveness. Hence, this work proposes an Effective Multiphase Scheduling Approach (EMSA) to process the jobs. In EMSA, the jobs are initially preprocessed and batched together to avoid starvation and to mitigate unwanted delay. Later, an Associate Priority Method has been proposed which prioritizes the batch jobs to minimize the number of migrations. Finally, the prioritized jobs are scheduled using Priority Scheduling with BackFilling algorithm to utilize the intermediate idle nodes. Moreover, the virtualization technology partitions the computing capacity of the Virtual Machine (VM) into two-tier VM as foreground VM (FVM) and Background VM (BVM) to improve node utilization. Hence, Priority Scheduling with Consolidation based BackFilling algorithm has been deployed in a two-tier VM that processes the jobs by utilizing the VMs effectively. Experimental results show that the performance of the proposed work performs better than other existing algorithms by increasing the resource utilization by 8%.     

Tensile and flexural properties of snake grass natural fiber reinforced isophthallic polyester composites

Natural fiber composite materials are one such capable material which replaces the conventional and synthetic materials for the practical applications where we require less weight and energy conservation. The present paper, which emphasis the importance of the newly identified snake grass fibers which are extracted from snake grass plants by manual process. In this paper, the tensile properties of the snake grass fiber are studied and compared with the traditionally available other natural fibers. The mixed chopped snake grass fiber reinforced composite is prepared by using the isophthallic polyester resin and the detailed preparation methodology is presented. Fiber pull-outs on the fractured specimen during the physical testing of the composites are also investigated. The experimental evidence also shows that the volume fraction increases the tensile, flexural strength and modulus of the snake grass fiber reinforce composite.     

Finite-time mixed H∞ and passive filtering for Takagi–Sugeno fuzzy nonhomogeneous Markovian jump systems

This paper is concerned with the finite-time mixed H_∞ and passivity performance analysis and filter design for a class of uncertain nonlinear discrete-time Markovian jump systems (MJSs) described by Takagi–Sugeno fuzzy model with nonhomogeneous jump processes. In this paper, the proposed MJSs fuzzy model is formulated with norm-bounded parameter uncertainties and time-varying jump transition probability matrices. In particular, the time-varying transition probability matrices are expressed in respect of a polytope. By constructing a suitable Lyapunov functional, a new set of sufficient conditions is derived in the form of linear matrix inequalities (LMIs) to ensure that the filtering error system is robustly stochastically finite-time bounded and a prescribed mixed H_∞ and passive performance index is achieved. Moreover, the robust mixed H_∞ and passivity filter design gain matrices can be computed from the obtained LMIs. Furthermore, the developed results unify H_∞ and passive filtering problems in a single framework. Finally, two numerical examples including an application-oriented example are provided to demonstrate the effectiveness of the proposed filter design technique.     

Photoinduced electron transfer from phenanthroimidazole to nano WO3, CuO ZrO2 and Al2O3. LUMO – CB energy binding efficiency relationship

A new kind of fluorophore 2-(4-fluorophenyl)-1-phenyl-1H-phenanthro [9,10-d] imidazole has been synthesized and characterized by ¹H NMR, ¹³C NMR and mass spectral studies. The dynamics of photoinduced electron injection and energy transfer from phenanthroimidazole to CuO, ZrO₂, WO₃ and Al₂O₃ nanocrystals has been studied by Fourier transform infrared spectroscopy (FT-IR), absorption, fluorescence and lifetime spectroscopic methods. The association between nanocrystals and phenanthroimidazole is explained by both absorption and fluorescence quenching data. The distance between phenanthroimidazole and nanocrystals as well as the critical energy transfer distance has been obtained. The free energy change (ΔG_et) for electron injection has also been deduced. Qualitative relationship exists between the efficiency of binding with the LUMO – CB energy gap and also the efficiency of binding with the HOMO – CB energy gap.     

Effect of nickel on the structural and magnetic properties of nano structured CoZnFe<Subscript>2</Subscript>O<Subscript>4</Subscript>

Nano particles of Co_(0.5–x)Ni_xZn_0.5Fe₂O₄ (x = 0–0.3) were synthesized by chemical coprecipitation method. Powder X-ray diffraction pattern confirms the formation of spinel phase for all the prepared samples. The lattice parameters were calculated from powder X-ray diffraction data and the result reveals that the values are less than that of bulk values. The saturation magnetization decrease for the concentration x = 0.1 and increases for all the other concentration. Further, the hysteresis loop for the concentration x = 0 and 0.1 shows that there is no coercivity and remanance at 300 K and hence the samples behaves as superparamagnetic at 300 K. The field-cooled (FC) and zero-field-cooled (ZFC) curve for the concentration x = 0 and 0.1 separates at 150 and 167 K respectively hence the prepared samples behaves as superparamagnetic at room temperature.     

Magnetic and dielectric properties of cadmium substituted nickel cobalt nanoferrites

Nano particles of Cd_XNi_(0.5?X)Co_0.5Fe₂O₄ (x = 0.0, 0.1, 0.2 and 0.3) were prepared by coprecipitation method. The lattice constant and distribution of cation in A-site and B-site have been deduced through X-ray diffraction (XRD) data analysis. The lattice constant (?) was found to increase with increase in Cd²⁺ concentration in the spinel structure of Ni–Co ferrites. The saturation magnetization was found to decrease with increase in Cd concentration for all the samples. It is observed that the Curie temperature (T_c) is higher than in bulk counterpart. The dielectric constant increases with increase in Cd concentration. This increase in dielectric constant is attributed to the formation of Fe³⁺ ion in the octahedral site which increases the hopping between Fe³⁺ and Fe²⁺.