Numerical Analysis for the Oxidation of Phenol with TiO2 in Wastewater Photocatalytic Reactors

Phenolic compounds in wastewater (even at low levels) are found to be quite toxic to humans due to their carcinogenic effects. Photocatalysis has been widely studied for the removal of phenol from industrial wastewater. In this study, photocatalytic oxidation of phenol, under UV irradiation in the presence of TiO2, has been numerically investigated. Phenol mass balance and forward finite difference method (explicit) along with various assumed/calculated parameters, from previous works, were used to numerically plot phenol concertation profiles in water with different initial phenol concentrations. Phenol compounds were observed to be totally oxidized at the bottom of the reactor and the maximum conversion rates occur near the reactor walls. It was found that higher irradiation times increase phenol oxidation rates due to higher water hydrolysis. Oxidation rate of phenol (consumption) increases with the increase in initial phenol concentration

Segmentation of corpus callosum using diffusion tensor imaging: validation in patients with glioblastoma

Abstract Background This paper presents a three-dimensional (3D) method for segmenting corpus callosum in normal subjects and brain cancer patients with glioblastoma. Methods Nineteen patients with histologically confirmed treatment naïve glioblastoma and eleven normal control subjects underwent DTI on a 3T scanner. Based on the information inherent in diffusion tensors, a similarity measure was proposed and used in the proposed algorithm. In this algorithm, diffusion pattern of corpus callosum was used as prior information. Subsequently, corpus callosum was automatically divided into Witelson subdivisions. We simulated the potential rotation of corpus callosum under tumor pressure and studied the reproducibility of the proposed segmentation method in such cases. Results Dice coefficients, estimated to compare automatic and manual segmentation results for Witelson subdivisions, ranged from 94% to 98% for control subjects and from 81% to 95% for tumor patients, illustrating closeness of automatic and manual segmentations. Studying the effect of corpus callosum rotation by different Euler angles showed that although segmentation results were more sensitive to azimuth and elevation than skew, rotations caused by brain tumors do not have major effects on the segmentation results. Conclusions The proposed method and similarity measure segment corpus callosum by propagating a hyper-surface inside the structure (resulting in high sensitivity), without penetrating into neighboring fiber bundles (resulting in high specificity)

Arcuate Fasciculus Abnormalities and Their Relationship with Psychotic Symptoms in Schizophrenia

Disruption of fronto-temporal connections involving the arcuate fasciculus (AF) may underlie language processing anomalies and psychotic features such as auditory hallucinations in schizophrenia. No study to date has specifically investigated abnormalities of white matter integrity at particular loci along the AF as well as its regional lateralization in schizophrenia. We examined white matter changes (fractional anisotropy (FA), axial diffusivity (AD), asymmetry indices) along the whole extent of the AF and their relationship with psychotic symptoms in 32 males with schizophrenia and 44 healthy males. Large deformation diffeomorphic metric mapping and Fiber Assignment Continuous Tracking were employed to characterize FA and AD along the geometric curve of the AF. Our results showed that patients with schizophrenia had lower FA in the frontal aspects of the left AF compared with healthy controls. Greater left FA and AD lateralization in the temporal segment of AF were associated with more severe positive psychotic symptoms such as delusions and hallucinations in patients with schizophrenia. Disruption of white matter integrity of the left frontal AF and accentuation of normal left greater than right asymmetry of FA/AD in the temporal AF further support the notion of aberrant fronto-temporal connectivity in schizophrenia. AF pathology can affect corollary discharge of neural signals from frontal speech/motor initiation areas to suppress activity of auditory cortex that may influence psychotic phenomena such as auditory hallucinations and facilitate elaboration of delusional content

Computation of metallic nanofluid natural convection in a two-dimensional solar enclosure with radiative heat transfer, aspect ratio and volume fraction effects

As a model of nanofluid direct absorber solar collectors (nano-DASCs), the present article describes recent numerical simulations of steady-state nanofluid natural convection in a two-dimensional enclosure. Incompressible laminar Newtonian viscous flow is considered with radiative heat transfer. The ANSYS FLUENT finite volume code (version 19.1) is employed. The enclosure has two adiabatic walls, one hot (solar receiving) and one colder wall. The Tiwari-Das volume fraction nanofluid model is used and three different nanoparticles are studied (Copper (Cu), Silver (Ag) and Titanium Oxide (TiO2)) with water as the base fluid. The solar radiative heat transfer is simulated with the P1 flux and Rosseland diffusion models. The influence of geometrical aspect ratio and solid volume fraction for nanofluids is also studied and a wider range is considered than in other studies. Mesh-independence tests are conducted. Validation with published studies from the literature is included for the copperwater nanofluid case. The P1 model is shown to more accurately predict the actual influence of solar radiative flux on thermal fluid behaviour compared with Rosseland radiative model. With increasing Rayleigh number (natural convection i.e. buoyancy effect), significant modification in the thermal flow characteristics is induced with emergence of a dual structure to the circulation. With increasing aspect ratio (wider base relative to height of the solar collector geometry) there is a greater thermal convection pattern around the whole geometry, higher temperatures and the elimination of the cold upper zone associated with lower aspect ratio. Titanium Oxide nano-particles achieve slightly higher Nusselt number at the hot wall compared with Silver nano-particles. Thermal performance can be optimized with careful selection of aspect ratio and nano-particles and this is very beneficial to solar collector designers

Fiber modeling and clustering based on neuroanatomical features

Abstract. DTI tractography allows unprecedented understanding of brain neural connectivity in-vivo by capturing water diffusion patterns in brain white-matter microstructures. However, tractography algorithms often output hundreds of thousands of fibers, rendering the computation needed for subsequent data analysis intractable. A remedy is to group the fibers into bundles using fiber clustering techniques. Most existing fiber clustering methods, however, rely on fiber geometrical information only by viewing fibers as curves in the 3D Euclidean space. The important neuroanatomical aspect of the fibers is mostly ignored. In this paper, neuroanatomical information is encapsulated in a feature vector called the associativity vector, which functions as the “fingerprint ” for each fiber and depicts the connectivity of the fiber with respect to individual anatomies. Using the associativity vectors of fibers, we model the fibers as observations sampled from multivariate Gaussian mixtures in the feature space. An expectation-maximization clustering approach is then employed to group the fibers into 16 major bundles. Experimental results indicate that the proposed method groups the fibers into anatomically meaningful bundles, which are highly consistent across subjects.

Aluminum Oxide Nanofluid Energy Transfer

Nanofluid is a new class of heat transfer fluids engineered by dispersing metallic or non-metallic nanoparticles with a typical size of less than 100 nm in the conventional heat transfer fluids.This article aims to investigate the overall and convection heat transfer coefficient and Nusselt number of Al2O3-water nanofluid flowing in a horizontal double pipe heat exchanger under turbulent flow () conditions. Al2O3 nanoparticles with diameter of 20 nm dispersed in Deionized water with volume concentrations of  vol. are used as the test fluid. The results show that the overall and convection heat transfer coefficient and Nusselt number of nanofluid were approximately 15% -21% greater than that of pure fluid. Additionally, the heat transfer coefficient and Nusselt number increase with an increase in flow rate,Reynolds number, nanoparticle concentration and nanofluid temperature. Finally, the new correlations were proposed for predicting the Nusselt number of the nanofluids, especially. Employing particles of nanometer dimension suspended in solution as nanofluid shows considerable increase in the nanofluid thermal conductivity and heat transfer coefficient which result in increasing heat transfer and decreasing operational cost