An Adaptive Rank Aggregation-Based Ensemble Multi-Filter Feature Selection Method in Software Defect Prediction

Feature selection is known to be an applicable solution to address the problem of high dimensionality in software defect prediction (SDP). However, choosing an appropriate filter feature selection (FFS) method that will generate and guarantee optimal features in SDP is an open research issue, known as the filter rank selection problem. As a solution, the combination of multiple filter methods can alleviate the filter rank selection problem. In this study, a novel adaptive rank aggregation-based ensemble multi-filter feature selection (AREMFFS) method is proposed to resolve high dimensionality and filter rank selection problems in SDP. Specifically, the proposed AREMFFS method is based on assessing and combining the strengths of individual FFS methods by aggregating multiple rank lists in the generation and subsequent selection of top-ranked features to be used in the SDP process. The efficacy of the proposed AREMFFS method is evaluated with decision tree (DT) and naïve Bayes (NB) models on defect datasets from different repositories with diverse defect granularities. Findings from the experimental results indicated the superiority of AREMFFS over other baseline FFS methods that were evaluated, existing rank aggregation based multi-filter FS methods, and variants of AREMFFS as developed in this study. That is, the proposed AREMFFS method not only had a superior effect on prediction performances of SDP models but also outperformed baseline FS methods and existing rank aggregation based multi-filter FS methods. Therefore, this study recommends the combination of multiple FFS methods to utilize the strength of respective FFS methods and take advantage of filter–filter relationships in selecting optimal features for SDP processes.     

Synthesis of 2,2'-arylmethylene bis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) in aqueous medium at room temperature

The reaction of dimedone with various aromatic aldehydes produces 2,2'-arylmethylene bis (3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) in excellent yields. The reactions occur in water as solvent at room temperature and avoiding the addition of any catalyst. The workup procedure is very simple and the products do not required further purification.     

Synthesis and application of a highly efficient tetraester calix[4]arene based resin for the removal of Pb from aqueous environment

The present study describes the Pb²⁺ sorption potential of newly synthesized tetraester calix[4]arene (TC4) based resin from aqueous media. The TC4 resin was synthesized through diazotization reaction of TC4 with Amberlite XAD-4 in the presence of sodium nitrite in acidic medium. The TC4 resin was characterized by using different analytical techniques such as FT-IR, elemental analysis and scanning electron microscopy (SEM). The Pb²⁺ removal ability of the resin from the aqueous environment has been evaluated by both batch adsorption as well as column studies. The experiments have been conducted involving the determination of effect of pH, adsorbate concentration, adsorbent dosage, contact time and temperature. Moreover, on the basis of kinetic studies, the pseudo-first-order and pseudo-second-order adsorption kinetics were calculated. The thermodynamic parameters of lead adsorption were also calculated. Equation isotherms such as Langmuir (L), Freundlich (F), and Dubinin-Radushkevich (D-R) were successfully used to model the experimental data. From the D-R isotherm parameters, it was considered that the uptake of Pb²⁺ by TC4 resin is ion exchange mechanism. From the results it has been found that the TC4 resin is a versatile adsorbent for the removal of Pb²⁺ from the aqueous environment. The study also confers its impact on human health, reinstate of polluted sites and other fields of material science.     

Phase Control of Transient Optical Properties of Double Coupled Quantum-Dot Nanostructure via Gaussian Laser Beams

We theoretically analyze the transient properties of a probe field absorption and dispersion in a coupled semiconductor double-quantum-dot nanostructure.We show that in the presence of the Gaussian laser beams,absorption and dispersion of the probe field can be dramatically influenced by the relative phase between applied fields and intensity of the Gaussian laser beams.Transient and steady-state behaviors of the probe field absorption and dispersion are discussed to estimate the required switching time.The estimated range is between 5–8 ps for subluminal to superluminal light propagation.     

Applications of Ionic Liquids in Whole-Cell and Isolated Enzyme Biocatalysis

Ionic liquids have unique chemical properties that have fascinated scientists in many fields. The effects of adding ionic liquids to biocatalysts are many and varied. The uses of ionic liquids in biocatalysis include improved separations and phase behaviour, reduction in toxicity, and stabilization of protein structures. As the ionic liquid state of the art has progressed, concepts of what can be achieved in biocatalysis using ionic liquids have evolved and more beneficial effects have been discovered. In this review ionic liquids for whole-cell and isolated enzyme biocatalysis will be discussed with an emphasis on the latest developments, and a look to the future.     

Isolation and characterisation of new bio-active compounds from Euphorbia cornigera: cytotoxic ingenol esters

The aerial parts of Euphorbia cornigera Boiss., on extraction with MeOH, yielded new bio-active constituents (1, 2) and known compounds (3 and 4) after MTT cytotoxicity assay-guided fractionation and chromatographic separation were conducted. From the aerial parts of E. cornigera Boiss., new bio-active constituents were extracted in methanol. The extract was partitioned in different organic solvents and the ethylacetate-soluble portion was subjected to Craig's distribution. The MTT cytotoxicity assay-guided chromatographic separation yielded four (1-4), out of which two (1, 2) were new and two known (3, 4) bio-active compounds, and they are reported for the first time from this source. Their structure and relative stereochemistry were established by analysing spectroscopic and mass measurement data. The isolates were named as: 13-O-[(2Z ,4 E ,6 Z)]-deca-2,4,6-trienoylingenol (1), 13-O-( 2 Z ,4 E ,6 Z)-deca-2,4,6-trienoyl-20-O-angeloylingenol (2), 13-O-dodecanoyl-20-O-hexanoylingenol (3) and 3-O-(2,3-dimethylbutanoyl)-13-O-dodecanoyl-20-O-hexadecanoylingenol (4). Literature revealed that compounds 1 and 2 are new metabolites, while 3 and 4 are known, and are reported for the first time from this source. Cytotoxicities of isolates were evaluated in terms of IC(50) against RAW and HT-29 cell lines through MTT assay using ambrucin hydrochloride as a control. Compound 3 showed more activity than control, while 1, 2 and 4 were moderate.     

The quasibound state model for self-consistent characteristics of semiconductor intersubband devices

The quasibound state model (QBSM) for determining the self-consistent conduction band profile and space charge density of semiconductor intersubband devices is presented. This new method is based on the quasibound (QB) state resonances of quantum structures. For heterostructures, the traditional self-consistent energy continuum model (ECM) calculates space charge by integration over the entire energy continuum, weighted by Fermi–Dirac statistics. In the present approach, the continuum of energy states of the heterostructure is accurately represented by a small number of QB states, and the space charge calculations are performed only at these eigen-energies. This approach significantly reduces the computational burden associated with all self-consistent algorithms. Theoretical formulation of QBSM is compared with the traditional ECM approach. The bound (B) and QB eigenenergies of the structure are obtained by solving the single-band effective-mass Schrödinger equation using the argument principle method. The performance and the accuracy of the QBSM are evaluated for a double-barrier resonant structure and an asymmetric Fabry–Perot electron-wave interference filter. The self-consistent electron density and potential profiles calculated by the present method are shown to be in excellent agreement with the results obtained from the traditional ECM model. In addition to requiring less computational time, the present method is easily implemented and may be applied equally well to biased/unbiased, symmetric/asymmetric heterostructures.     

Spatial Frequency Response and Transient Anisotropy in Bacteriorhodopsin Thin Films

In this paper, we present new results describing the spatial frequency response in bacteriorhodopsin (bR), immobilised in gelatin films. It is shown that the spatial frequency response is flat, as compared to bR contained in solution form. An experimental investigation into the photoinduced anisotropy of bR films is also presented. It is shown that the anisotropy can be induced using two wavelengths (632.8 nm and 454 nm) and is dependent on the pH of the gelatin matrix, the 454 nm laser polarisation and the 454 nm pump power. The mechanisms producing the anisotropy are briefly discussed.Presented at the International Commission of Optics Topical Meeting, Kyoto, 1994.