Conformationally locked bridged bicyclic diselenides: synthesis, structure, Se...O interaction, and theoretical studies

A general synthetic methodology has been developed for the synthesis of a conformationally locked, bridged diselena-bicyclo[3.2.1]octane skeleton by regio- and stereospecific tandem nucleophilic ring opening of cis-1,4-aziridino-epoxides with tetraethylammonium tetraselenotungstate [Et4N]2WSe4, 1, in a one-pot synthesis. Some correlations have been made on the physicochemical characteristics of the diselenides with a change in the dihedral angles.     

Regio- and stereospecific synthesis of beta-sulfonamidodisulfides and beta-sulfonamidosulfides from aziridines using tetrathiomolybdate as a sulfur transfer reagent

A comprehensive study of a general and effective one-step procedure for the synthesis of beta-sulfonamidodisulfides directly from N-tosyl aziridines in a regio- and stereospecific manner under neutral conditions without the use of any Lewis acid or base has been reported. This methodology is extended to the synthesis of an optically pure cyclic seven-membered disulfide 29. Synthesis of a variety of beta-sulfonamidosulfides involving tandem, multistep reactions in one pot is also reported.     

A novel extracellular synthesis of monodisperse gold nanoparticles using marine alga, Sargassum wightii Greville

The process of development of reliable and eco-friendly metallic nanoparticles is an important step in the field of nanotechnology. To achieve this use of natural sources like biological systems becomes essential. In the present, work we have investigated extracellular biosynthesis of gold nanoparticles using Sargassum wightii and have achieved rapid formation of gold nanoparticles in a short duration. The UV-vis spectrum of the aqueous medium containing gold ion showed peak at 527 nm corresponding to the plasmon absorbance of gold nanoparticles. Transmission electron microscopy (TEM) showed formation of well-dispersed gold nanoparticles in the range of 8-12 nm. X-ray diffraction (XRD) spectrum of the gold nanoparticles exhibited Bragg reflections corresponding to gold nanoparticles.     

Poissonian Behavior of Ising Spin Systems in an External Field

We apply the Stein–Chen method for Poisson approximation to spin-half Ising-type models in positive external field which satisfy the FKG inequality. In particular, we show that, provided the density of minus spins is low and can be expanded as a convergent power series in the activity (fugacity) variable, the distribution of minus spins is approximately Poisson. The error of the approximation is inversely proportional to the number of lattice sites (we obtain upper and lower bounds on the total variation distance between the exact distribution and its Poisson approximation). We illustrate these results by application to specific models, including the mean-field and nearest neighbor ferromagnetic Ising models.     

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.     

Particle Sizing Using Frequency Domain Photon Migration

The transport properties of particulate process streams and their final product quality, are directly affected by critical parameters of particle size distribution, f(x), and volume, mass, or number density of particles or dispersed phase droplets. A method is proposed for the potential on-line monitoring of particle size distribution and volume fraction in real time, using frequency-domain photon migration measurements (FDPM). Theory, experimental measurements, and results for the determination of particle size distributions for both a polystyrene latex and a titanium dioxide suspension determined using the photon migration technique are presented. The critical issues associated with the application of photon migration to particulate and dispersed phase processes are discussed, including the effects of interparticle interactions on the transport of light.     

Distributed adaptive control for multiple under-actuated Lagrangian systems under fixed or switching topology

Nonlinear Dynamics - This paper presents distributed adaptive tracking control algorithms under fixed or switching communication graph for a team of agents, each of which is a special class of...     

Multiscale Model for Assessing the Effect of Bacterial Growth on Intrinsic Permeability of Soil: Column Experiment Simulation

A multiscale model was proposed in a companion paper for assessing the impact of bacterial growth attached to soil particles on the intrinsic permeability of soil. In this paper, this model is used to simulate a column experiment. The simulation conditions are described and the results of the simulation runs are presented. Various possible explanations for the observed reduction in permeability in the column experiment are analyzed using the model and it is concluded that the reduction in the metabolic activity of the attached biomass at the bottom of the column is mainly responsible for the reduction in the intrinsic permeability near the top of the column. Based on the set of parameter values used in the simulations, upper and lower bounds on the reduction in metabolic activity are estimated.     

Gamma radiation dose rate in indoor, outdoor and underground atmosphere around Tehri dam project, Uttarakhand, India

The natural pollution level due to gamma radiation was measured in about 22 residential houses around the Tehri Dam Project in Uttarakhand state by using Environmental Radiation Dosimeter. Both urban and rural houses were selected for the measurements. The recorded gamma dose rate in indoor atmosphere was found to vary from 25.1 μR/h to 67 μR/h with a mean value 38.6 μR/h whereas in traditional rural houses the obtained values varied from 42.6 μR/h to 83.5 μR/h with mean value 60.3 μR/h. In outdoor atmosphere, it was found to vary from 25.1 μR/h to 60 μR/h with an average value 35.8 μR/h. It is observed that the dose rates are higher in rural houses than that in modern houses. Efforts have also been made to observe deviation of dose rate in the underground (Power House) atmosphere of Tehri Dam Project in vertical and horizontal mode. It was observed that dose rate remain almost same in horizontal mode, but a significant variation has been found in the vertical mode. In addition, the variation of dose rate with type of building material, trend and mode of construction of houses and the age of houses are also discussed in detail.