Effect of time lapse on the diagnostic accuracy of cone beam computed tomography for detection of vertical root fractures

Accurate and early diagnosis of vertical root fractures (VRFs) is imperative to prevent extensive bone loss and unnecessary endodontic and prosthodontic treatments. The aim of this study was to assess the effect of time lapse on the diagnostic accuracy of cone beam computed tomography (CBCT) for VRFs in endodontically treated dog’s teeth. Forty-eight incisors and premolars of three adult male dogs underwent root canal therapy. The teeth were assigned to two groups: VRFs were artificially induced in the first group (n=24) while the teeth in the second group remained intact (n=24). The CBCT scans were obtained by NewTom 3G unit immediately after inducing VRFs and after one, two, three, four, eight, 12 and 16 weeks. Three oral and maxillofacial radiologists blinded to the date of radiographs assessed the presence/absence of VRFs on CBCT scans. The sensitivity, specificity and accuracy values were calculated and data were analyzed using SPSS v.16 software and ANOVA. The total accuracy of detection of VRFs immediately after surgery, one, two, three, four, eight, 12 and 16 weeks was 67.3%, 68.7%, 66.6%, 64.6%, 64.5%, 69.4%, 68.7%, 68% respectively. The effect of time lapse on detection of VRFs was not significant (p>0.05). Overall sensitivity, specificity and accuracy of CBCT for detection of VRFs were 74.3%, 62.2%, 67.2% respectively. Cone beam computed tomography is a valuable tool for detection of VRFs. Time lapse (four months) had no effect on detection of VRFs on CBCT scans. © 2016, Associacao Brasileira de Divulgacao Cientifica. All rights reserved

INFLUENCE OF THE CHEMICAL STRUCTURE OF ORGANIC POLLUTANTS ON PHOTOCATALYTIC ACTIVITY OF TiO 2 NANOPARTICLES: KINETIC ANALYSIS AND EVALUATION OF ELECTRICAL ENERGY PER ORDER (E EO )

Photocatalytic degradation of different organic pollutants such as C.I. Acid Red 27(AR27), Methyl Orange (MO), Malachite Green (MG) and 4-Nitrophenol (4-NP) were investigated under UV light irradiation using synthesized TiO 2 nanoparticles by sol-gel method. It was found that the photocatalytic degradation rate depends on pollutants structure. The results indicate that from these pollutants MG can be removed faster than other pollutants. Also, 4-NP with a more stable structure than other pollutants has lowest removal rate in the presence of TiO 2 nanoparticles under UV light irradiation. The results prove that removal rate of pollutants with different structures follows pseudo-first order kinetics. The figures-of-merit based on electric energy consumption (electrical energy per order (E EO )) were evaluated in the photocatalytic degradation of four organic pollutants. The results indicate that E EO values depend on the basic structure of the pollutants

Study of the Effect of Additives on the Photocatalytic Degradation of a Triphenylmethane Dye in the Presence of Immobilized TiO₂/NiO Nanoparticles: Artificial Neural Network Modeling

In the present work, TiO₂/NiO coupled nanoparticles were prepared from a powder mixture of the corresponding component solid oxides by using an impregnation technique. Then, the prepared TiO₂/NiO nanoparticles were immobilized on glass plate and used as a fixed-bed photocatalytic system for photodegradation of Acid Fuchsin (AF), as a triphenylmethane dye pollutant. The effects of nature and concentration of various additives included inorganic oxidants (such as HSO₅^–, IO₄^–, ClO₃^–, S₂O₈^2–, H₂O₂, and BrO₃^–), inorganic anions (such as CH₃COO^–, CO₃^2–, NO₃^–, Cl^–, H₂PO₄^–, and SO₄^2–), and transition-metal ions (such as Co²⁺, Zn²⁺, Fe²⁺, Cu²⁺, Ni²⁺, and Mn²⁺) on photocatalytic degradation of AF, were investigated. It was found that the nature and concentration of studied additives significantly affected the photocatalytic degradation of dye pollutant in fixed-bed systems. The transition-metal ions and inorganic oxidants have a positive effect on the photocatalytic degradation rate of AF dye, whereas inorganic anions have a negative effect. An artificial neural network (ANN) model was designed for modeling of the photocatalytic degradation rate of AF dye. The results showed that the predicted data from designed ANN model were in good agreement with the experimental data. Designed ANN provides a reliable method for modeling the photocatalytic activity of immobilized TiO₂/NiO nanoparticles in the presence of various additives

Horizontally rotating disc recirculated photoreactor with TiO₂-P25 nanoparticles immobilized onto a HDPE plate for photocatalytic removal of <i>p</i>-nitrophenol

<p>In this study, a horizontally rotating disc recirculated (HRDR) photoreactor equipped with two UV lamps (6 W) was designed and fabricated for photocatalytic removal of <i>p</i>-nitrophenol (PNP). Photocatalyst (TiO₂) nanoparticles were immobilized onto a high-density polyethylene (HDPE) disc, and PNP containing solution was allowed to flow (flow rate of 310 mL min^–1) in radial direction along the surface of the rotating disc illuminated with UV light. The efficiency of direct photolysis and photocatalysis and the effect of rotating speed on the removal of PNP were studied in the HRDR photoreactor. It was found that TiO₂-P25 nanoparticles are needed for the effective removal of PNP and there was an optimum rotating speed (450 rpm) for the efficient performance of the HRDR photoreactor. Then effects of operational variables on the removal efficiency were optimized using response surface methodology. The results showed that the predicted values of removal efficiency are consistent with experimental results with an <i>R</i>₂ of 0.9656. Optimization results showed that maximum removal percent (82.6%) was achieved in the HRDR photoreactor at the optimum operational conditions. Finally, the reusability of the HRDR photoreactor was evaluated and the results showed high reusability and stability without any significant decrease in the photocatalytic removal efficiency.</p

High-temperature stable anatase-type TiO2nanotube arrays: A studyof the structure–activity relationship

Anatase-type TiO2 nanotube arrays (TiO2-NTAs) were grown on Ti foil by anodic oxidation inCH3COOH/NH4F solutions followed by thermal treatment. The surface of TiO2-NTAs was further deco-rated by palladium and silver metal clusters through a chemical-reduction method and its photocatalyticactivity was tested by investigating the degradation of p-nitrophenol (PNP) in aqueous solutionunder visible-light irradiation and electrical polarization. The effects of preparation variables bothon microstructural properties of samples and photocatalytic activity were examined by using the 3Dresponse surface and the 2D contour plots. The experimental investigations carried out by using XRD,SEM, HRTEM, EDS, XRF, ICP-AES, XPS, DRS, and PL, demonstrated a strong relation between the phasestructure and the photocatalytic activity of TiO2-NTAs. Titania nanotubes grown in acetic acid solutionand thermally post-treated have stable anatase crystal structure, to a point that by performing annealingat 800◦C for 3 h, only the 35% of anatase transforms into rutile. Finally, it was shown that the TiO2-NTAs decorated with Pd(0.72 wt%) and Ag(1.26 wt%) particles show higher photocatalytic activity comparedwith nanotubes modified with single metal particles. It is believed that the high photoactivity of TiO2 nanotubes decorated with Pd–Ag heterostructures is due to the prolonged lifetimes of photogenerated electron–hole pairs. The possible mechanism for the enhanced photocatalytic activity is discussed in detail

Synthesis of Highly Monodispersed, Stable, and Spherical NZVI of 20–30 nm on Filter Paper for the Removal of Phosphate from Wastewater: Batch and Column Study

A nanobiodegradable adsorbent was prepared by stabilizing nanoscale zerovalent iron (NZVI) on cellulose filter paper. Characterization of the sample disclosed that the NZVI particles were rounded, well-monodispersed through the paper, and smaller than 30 nm in diameter. We explored this material’s ability to capture phosphate ions in batch and repeated operations, specifically studying the impact of pH, adsorption time, initial phosphate concentration, interference ions, and temperature. The equilibrium results were matched to dissimilar kinds of adsorption isotherms, with the Sips adsorption model displaying the best match. The stabilized NZVI indicated high reusability after 7 adsorption–desorption cycles. We also demonstrated how this nanobiodegradable adsorbent could be applied to eliminate phosphate ions from a real water source (<i>Cayuga Lake</i>). In the continuous system, the results confirmed that an enhancement in the initial phosphate ion concentration improved the phosphate removal ability of the filter-paper-stabilized NZVI, likely due to more motive power for mass transfer by the greater phosphate concentration. However, an enhancement in bed height and flow rate reduced phosphate removal because of the higher flow rate decreasing the reaction time of the solution and adsorbent, whereas the higher bed height resulted in a channeling effect. Breakthrough curves gained from fixed-bed column tests showed the strong potential of the NZVI for phosphate ion sequestration. An artificial neural network model was used to envision the phosphate ions removal in both batch and continuous systems by this composite. The adsorption mechanism of phosphate onto the filter-paper-stabilized NZVI was further investigated by X-ray spectroscopy, X-ray diffraction, elemental mapping, and zeta potential techniques