Development of an Artificial Intelligence Method to Detect COVID-19 Pneumonia in Computed Tomography Images

Introduction:This study aimed to construct an artificial intelligence system to detect Coronavirus disease-2019 (COVID-19) pneumonia on computed tomography (CT) images and to test its diagnostic performance.Methods:Data were acquired between March 18-April 17, 2020. CT data of 269 reverse tran-scriptase-polymerase chain reaction proven patients were extracted, and 173 studies (122 for training, 51 testing) were finally used. Most typical lesions of COVID-19 pneumonia were la-beled by two radiologists using a custom tool to generate multiplanar ground-truth masks. Us-ing a patch size of 128x128 pixels, 18,255 axial, 71,458 coronal, and 72,721 sagittal patches were generated to train the datasets with the U-Net network. Lesions were extracted in the or-thogonal planes and filtered by lung segmentation. Sagittal and coronal predicted masks were reconverted to the axial plane and were merged into the intersect-ed axial mask using a voting scheme.Results:Based on the axial predicted masks, the sensitivity and specificity of the model were found as 91.4% and 99.9%, respectively. The total number of positive predictions has increased by 3.9% by the use of intersected predicted masks, whereas the total number of negative predic-tions has only slightly decreased by 0.01%. These changes have resulted in 91.5% sensitivity, 99.9% specificity, and 99.9% accuracy.Conclusion:This study has shown the reliability of the U-Net architecture in diagnosing typical pulmonary lesions of COVID-19 in CT images. It also showed a slightly favorable effect of the intersection method to increase the model’s performance. Based on the performance level pre-sented, the model may be used in the rapid and accurate detection and characterization of the typical COVID-19 pneumonia to assist radiologists

Catalytic oxidation of nitrogen containing compounds for nitrogen determination

The high temperature catalytic oxidation (HTCO) performance of Al2O3 supported Pt, Cu, Cu-Ce and Fe catalysts were systematically studied with a perspective of selective oxidation of nitrogenous compounds to nitric oxide for quantitative determination of bound nitrogen. The catalyst samples were prepared via impregnation and characterized by XRD and BET. In addition, temperature programmed reaction experiments with acetonitrile and oxygen were conducted to evaluate the catalytic activity and selectivity toward N-2, N2O and NO. The catalyst samples were also tested for model components; urea, EDTA, pyridine, glutamic acid and ammonium sulfate representing different functional groups

Catalyst For Complete Oxidation of Nitrogen Containing Samples

High temperature catalytic oxidation of nitrogen containing compounds has great importance for the analysis of environmental and industrial samples and the control of emissions of waste incineration facilities.The complete oxidation of nitrogen in different functional groups to NO and NO2is a crucial step for the determination of nitrogen in samples and NOxabatement[1,2]. Altough platinum group metals have excellent oxidation activity, they are expensive and easily poisoned by the presence of S, Cl and P containing organic substances. Therefore, there is a great interest to develop new active, selective and resistant catalyst to treat waste oxidation gases. In this study, the activities of CuO/ Al2O3, CuO-CeO2/ Al2O3and Pt/ Al2O3catalysts for total oxidation of nitrogen containing compounds were analyzed. The catalyst samples were prepared to obtain a loading of 10% Cu, 3%Cu-7%Ce, 1% Pt over the Al2O3as a suppport by impregnation method. Characterization of the catalyst samples was performed by X-ray powder diffraction (XRD) and BET. EDTA, urea, potassium nitrate, ammonium chloride, thiourea, pyridine, glycine, yeast extract, metylaminewere selected as model components representing various nitrogen containing functional groups. The experiments were performed in a quartz tubular reactor in two zone furnace and the sample first oxidized at 700-850 oC under air flow of 200 ml/min and the cataytic oxidation was performed at 500oC in second zone, gas stream passed over catalytic bed. The catalytic activities of the samples were investigated with mass spectrometry by analyzing combustion products. In table 1, BET surface area values of the catalysts samples are given. It is seen that the surface area changes significantly when impregnating cerium and copper on Al2O3

Fatigue strength estimation of butt welded joints in magnesium AZ31 alloy using the genetic algorithm

Genetic Algorithm is applied to calculate the substitute structural length (SSL) and obtain the fatigue strength of welded joints in magnesium. Fatigue tests with unnotched and notched specimens of the base material metal (BM), the weld metal (WM) and the heat-affected zone (HAZ) of magnesium AZ31 (MgA13) were carried out in order to derive the unknown substitute structural length. Results of fatigue tests with geometrically similar welded joints with full and partial penetration were available. The comparison of the experimental and predicted substitute structural length using Genetic Algorithm Substitute Structural Length Estimation Model (GASLEM) shows that the developed models seem to be capable of predicting the SSL values. Fatigue strength values were also obtained using predicted SSL. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA

The effects of the intraamygdalar melatonin injections on the anxiety like behavior and the spatial memory performance in male Wistar rats

In the present study, the effects of intraamygdalar administrations of melatonin (1 and 100 mu g/kg), saline and diazepam on the anxiety-like behavior and spatial memory performance in pinealectomized and sham-pinealectomized Wistar rats were investigated. The animals were tested by open field and elevated plus maze tests for anxiety-like behavior, and Morris water maze test for spatial memory. In open field, (a) diazepam was more effective in reducing the anxiety, (b) control subjects were more mobile than pinealectomized subjects and (c) 100 mu g/kg melatonin administrations reduced the velocity of the animals. In elevated plus maze, (a) 100 mu g/kg melatonin administrations increased the distance totally travelled and (b) enhanced the time spent in open arms, however, after the pinealectomy, 1 mu g/kg melatonin administrations decreased it and (c) control animals were less mobile than pinealectomized ones. In Morris water maze, (a) diazepam group travelled more distance than the others in control condition whereas, in pinealectomy condition high dose of melatonin and saline groups travelled more distance than the others, (b) in pinealectomy condition subjects who received 100 mu g/kg melatonin also travelled more distance than those who received 1 mu g/kg melatonin and diazepam, (c) the subjects who received 1 mu g/kg spent less time than those who received other treatments, and (d) in control condition subjects who received 100 mu g/kg melatonin were slower than those who received the other treatments. In conclusion, melatonin administration to amygdala decreased the anxiety; however, spatial memory performance of the rats was impaired by the pinealectomy and melatonin administrations. (C) 2011 Elsevier B.V. All rights reserved

Çernobil nükleer faciasının insan yaşamı ve çevre üzerindeki etkileri

Ankara : İhsan Doğramacı Bilkent Üniversitesi İktisadi, İdari ve Sosyal Bilimler Fakültesi, Tarih Bölümü, 2012.This work is a student project of the The Department of History, Faculty of Economics, Administrative and Social Sciences, İhsan Doğramacı Bilkent University.by İbrahim Mert Öztürk.Öztürk, İbrahim Mert. HIST 203-06ÖZTÜRK HIST 203-06/6 2011-1

Fatigue design values for welded joints of the wrought magnesium alloy AZ31 (ISO-MgAl3Zn1) according to the nominal, structural and notch stress concepts in comparison to welded steel and aluminium connections

The following investigation provides knowledge about the fatigue behaviour of welded wrought magnesium alloy AZ31 (ISO-MgAI3Zn1). Three different types of joints, fully penetrated and partially penetrated butt welds, transversal stiffeners, were tested under fully reversed (R = -1), pulsating (R = 0) and high mean tensile (R = 0.5) loadings. The results were presented according to the nominal, structural (hot-spot) and notch stress (rf =1.0 and 0.05 mm) concepts. For these four concepts the FAT - values according to IIW - Recommendations were derived and compared with those already known for welded steel and aluminium joints