Dispersion study for two‐dimensional modelling

Simulation of water quality variation in a particular river stretch or at a particular location with time requires mathematical modelling based on advection and dispersion phenomenon. In this context, estimation of an appropriate dispersion coefficient, which is a function of characteristics of a water body, is very essential and forms an important step in mathematical modelling. The tracer study conducted in this context on the river Ganga to estimate the dispersion coefficient is described in this paper with an analysis of data based on a stream‐tube approach. For the wide river Ganga, with a velocity in the range 0.3–0.5 m/s, the estimated transverse dispersion coefficient is 1.33 m²/s.     

Analyzing the fractal feature of nickel thin films surfaces modified by low energy nitrogen ion

Fractal concepts are used to explore how different energies (10, 20 and 50 keV) and fluence of 5 × 10¹⁷ N⁺ cm^?2 affect the morphology of nickel thin film. The nickel thin film with thickness of 100 nm is prepared by electron beam evaporation technique at room temperature on stainless steel (AISI 316) substrates. The nanoscale three‐dimensional (3‐D) surface micro‐morphologies are investigated by atomic force microscopy (AFM). Interface width is used to describe the surface height fluctuations. The autocorrelation function with height‐height correlation function give the quantitative data about the morphology of surface. The value of roughness exponent and fractal dimension is computed by height‐height correlation function. Fractal measure is an important analysis which provides fundamental insights into the texture characteristics and a direct way of testing their functional role.     

A nucleation mechanism leading to stacking of lamellar crystals in polymer thin films

Systematic studies based on well‐controllable model systems aim at understanding how crystallization from a melt or solution of randomly coiled polymers leads to the formation of mono‐lamellar crystals. However, besides mono‐lamellar crystals also various other morphologically simple but yet not well understood structures are found. In particular, stacks of correlated lamellar crystals have been observed since the early days of the study of polymer crystallization. Here, we demonstrate that a recently proposed mechanism of self‐induced nucleation within lamellar crystals provides a possibility to explain how in such stacks lamellar crystals can be correlated. Examining various polymer systems, we show that the probability for generating self‐induced nuclei depends on the morphology of an initiating dendritic basal lamellar crystal. In addition, we provide evidence that this self‐induced nucleation mechanism, together with a high rate of transport of molten polymer to the fold surface, may allow the formation of polymer crystals with similar size in all three dimensions, containing a large number of superposed correlated lamellae. © 2019 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

A DE-ANN Inspired Skin Cancer Detection Approach Using Fuzzy C-Means Clustering

Mobile Networks and Applications - As per recent developments in medical science, the skin cancer is considered as one of the common type disease in human body. Although the presence of melanoma is...     

PET Performance Evaluation of an MR-Compatible PET Insert

A magnetic resonance (MR) compatible positron emission tomography (PET) insert has been developed in our laboratory for simultaneous small animal PET/MR imaging. This system is based on lutetium oxyorthosilicate (LSO) scintillator arrays with position-sensitive avalanche photodiode (PSAPD) photodetectors. The PET performance of this insert has been measured. The average reconstructed image spatial resolution was 1.51 mm. The sensitivity at the center of the field of view (CFOV) was 0.35%, which is comparable to the simulation predictions of 0.40%. The average photopeak energy resolution was 25%. The scatter fraction inside the MRI scanner with a line source was 12% (with a mouse-sized phantom and standard 35 mm Bruker 1H RF coil), 7% (with RF coil only) and 5% (without phantom or RF coil) for an energy window of 350-650 keV. The front-end electronics had a dead time of 390 ns, and a trigger extension dead time of 7.32 μs that degraded counting rate performance for injected doses above ~0.75 mCi (28 MBq). The peak noise-equivalent count rate (NECR) of 1.27 kcps was achieved at 290 μCi (10.7 MBq). The system showed good imaging performance inside a 7-T animal MRI system; however improvements in data acquisition electronics and reduction of the coincidence timing window are needed to realize improved NECR performance.     

Absence of Gut Microbiota Is Associated with RPE/Choroid Transcriptomic Changes Related to Age-Related Macular Degeneration Pathobiology and Decreased Choroidal Neovascularization

Studies have begun to reveal significant connections between the gut microbiome and various retinal diseases, including age-related macular degeneration (AMD). As critical supporting tissues of the retina, the retinal pigment epithelium (RPE) and underlying choroid play a critical role in retinal homeostasis and degeneration. However, the relationship between the microbiome and RPE/choroid remains poorly understood, particularly in animal models of AMD. In order to better elucidate this role, we performed high-throughput RNA sequencing of RPE/choroid tissue in germ-free (GF) and specific pathogen-free (SPF) mice. Furthermore, utilizing a specialized laser-induced choroidal neovascularization (CNV) model that we developed, we compared CNV size and inflammatory response between GF and SPF mice. After correction of raw data, 660 differentially expressed genes (DEGs) were identified, including those involved in angiogenesis regulation, scavenger and cytokine receptor activity, and inflammatory response—all of which have been implicated in AMD pathogenesis. Among lasered mice, the GF group showed significantly decreased CNV lesion size and microglial infiltration around CNV compared to the SPF group. Together, these findings provide evidence for a potential gut–RPE/choroidal axis as well as a correlation with neovascular features of AMD.     

Development and qualification of a VH-TDMA for the study of pure aerosols

We create and qualify a Volatility and Hygroscopicity Tandem Differential Mobility Analyzer (VH-TDMA) for the study of aerosols. This VH-TDMA measures size distributions, volatility, and hygroscopicity and includes an auxiliary conditioner that allows quick connection to other external aerosol conditioners. The differential mobility analyzers are not temperature controlled, allowing the surrounding environment to influence the measurement conditions, and this is fully accounted for when measuring aerosol volatility and hygroscopicity. For the volatility conditioner, the VH-TDMA uses a 15?m coil of tubing in an oven to evaporate aerosol samples at elevated temperatures. We measured several single component model aerosols to qualify the differential mobility particle sizer (DMPS) channel and each of the conditioners: hygroscopicity and volatility. Due to insufficient power supply calibration in this study, the TDMA channel is limited to particle sizes greater than 70?nm. The DMPS channel was able to reproduce ammonium sulfate size distributions when compared to common scanning mobility particle sizers. For hygroscopicity, the standard deviation in the measured ammonium sulfate growth factors was 0.03 over a 4-h experiment. From this data, the TDMA has an observed relative humidity error of ±0.6% with manufacturer reported error of ±1.2% relative humidity. The volatility channel reproduced the previously published saw tooth pattern of room temperature saturation vapor pressures from atomized C3-C9 diacids. The maximum percent difference in room temperature saturation vapor pressure was approximately 80%. The enthalpy of sublimation derived from the diacids increased monotonically (except for suberic acid) and resembled measurements from mass effusion techniques.

Copyright © 2019 American Association for Aerosol Research     

Corruption-tolerant bandit learning

We present algorithms for solving multi-armed and linear-contextual bandit tasks in the face of adversarial corruptions in the arm responses. Traditional algorithms for solving these problems assume that nothing but mild, e.g., i.i.d. sub-Gaussian, noise disrupts an otherwise clean estimate of the utility of the arm. This assumption and the resulting approaches can fail catastrophically if there is an observant adversary that corrupts even a small fraction of the responses generated when arms are pulled. To rectify this, we propose algorithms that use recent advances in robust statistical estimation to perform arm selection in polynomial time. Our algorithms are easy to implement and vastly outperform several existing UCB and EXP-style algorithms for stochastic and adversarial multi-armed and linear-contextual bandit problems in wide variety of experimental settings. Our algorithms enjoy minimax-optimal regret bounds, as well as can tolerate an adversary that is allowed to corrupt upto a universally constant fraction of the arms pulled by the algorithm.

     

Comparative study of the determination of platinum by extraction with Cyanex 923 and Cyanex 471X from bromide media

The extraction equilibrium study of Pt(IV) was carried out with Cyanex 923 and Cyanex 471X in toluene from hydrobromic acid media to investigate their extraction capacity, since they have different donor atoms, ‘O’ and ‘S’. Their distribution equilibria were studied as a function of extractant concentration, diluents, hydrobromic acid concentration and the effect of temperature on extraction. Pt(IV) was quantitatively extracted with 0.1 mol dm^?3 Cyanex 923 in toluene from 5.0–8.0 mol dm^?3 HBr media and was stripped with 4.0 mol dm^?3 perchloric acid. However it was also quantitatively extracted with 0.1 mol dm^?3 Cyanex 471X (with 0.1 mol dm^?3SnCl₂) in toluene from 6.0–8.0 mol dm^?3 HBr media and was stripped with 1.0 mol dm^?3 stabilized sodium thiosulfate solution at pH 9.0. The slope analysis method indicated metal complex species of 1:1 for Pt(IV) with Cyanex 923 and Cyanex 471X in toluene from HBr media. These methods were successfully applied to the analysis of platinum in real samples. © 2001 Society of Chemical Industry     

Effect of Temperature on Structural and Optical Properties of Boehmite Nanostructure

The nanocrystalline boehmite, γ‐AlOOH, was synthesized by the hydrothermal method using AlCl₃·6H₂O and urea as precursors, and the effect of different annealing temperatures resulting in different phases of alumina (Al₂O₃) was obtained. The effects of different temperature on the phase and micrographs of the prepared γ‐AlOOH nanostructures were investigated. The obtained products were characterized by X‐ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy techniques. The XRD results show that with the increasing temperature, the transformation of boehmite into well‐crystallized α‐Al₂O₃ and the morphology from nanoplatelets with spindle‐like edges to vermicular structure take place. The crystallite size and lattice parameters were calculated by Rietveld refinement. The convincing evidence for the crystal phase of the as‐prepared and annealed samples was provided by FTIR spectra. The Raman spectra unveil the change in vibrational modes of the phase transition alumina.