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Mathematical modeling of a methanol reactor by using different kinetic models
Grazia Leonzio 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.85 No.-
In this research, a mathematical model for an industrial methanol reactor is developed comparingdifferent kinetic models: Graaf et al., Vanden Bussche and Froment, pseudofirst order and pseudo zeroorder. Similar studies have not been carried out previously. The considered reactor is multi-tubularwith a methanol productivity of 2061 ton/day. Comparing the results obtained by mathematicalmodels with experimental data, it is evident that only the Vanden Bussche and Froment kinetic modeldescribes the methanol industrial reactor better. Also, it results that for all kinetic models, theeffectiveness factor is equal to 1: for industrial reactors at high pressure and low temperaturelimitation phenomena are not present (the calculated Weis-Prater parameter is equal to 0.03). Asensitivity analysis is developed to analyze the effect of recycling ratio, global heat exchangecoefficient, temperature, pressure, tube diameter on carbon conversion and specific heatflux. Byincreasing the recycling ratio and temperature, carbon conversion decreases, while by increasing allparameters, excluding the recycling ratio, the exchanged heat decreases. Different feeds are alsoanalyzed: coke oven gas allows the highest methanol production, whileflue gas and hydrogen fromwater electrolysis ensure the lowest productivity.
Application of the Seven-Factor-Model of Personality to an Italian Preschool Sample
Maria Grazia Melegari,Assunta Marano,Margherita Innocenzi,Loredana De Rosa,Renato Donfrancesco,Sandor Rozsa,C. Robert Cloninger 대한신경정신의학회 2014 PSYCHIATRY INVESTIGATION Vol.11 No.4
Objective Advances in dimensional assessment of children in healthy and clinical populations has renewed interest in the study of temperament. Cloninger’s Temperament and Character Inventory (TCI) has shown high reliability and internal consistency. Adult and adolescent versions have been translated into a number of languages and validated in cross-cultural studies worldwide. To date only one preschool-TCI-based study has been conducted in early infancy with teachers as observers. The present study is aimed to test an Italian Preschool version of the Temperament and Character Inventory (PsTCI). This is the first replication and the first validation study of TCI on preschoolers with parents as observers. Methods 395 preschool children, recruited from pediatric communities and day-care centres throughout Italy, participated in the study. Parents of each child enrolled in the study and completed a PsTCI about the child. Standard psychometric tests of reliability and validation were performed. Results Exploratory factor analyses demonstrated the presence of distinct domains for temperament and character. TCI dimensions had good internal consistency with Cronbach’s alpha ranging values (|0.60|–|0.81|). Gender differences were found for Harm Avoidance (β=-0.186; p≤0.001) and Self-Directedness (β=-0.216; p≤0.01), and accounted for 5–35% of the observed variance. Conclusion The present work suggests the psychological complexity of Cloninger’s model and confirms its application in pre-school children from diverse environmental and cultural backgrounds. The results confirm that Cloninger’s instrument for temperament and character evaluations can also be used with different observers and highlight the importance of considering cultural and demographic differences in the assessment of temperament and character in preschoolers.
GRB970228 in the "Canonical GRB" Scenario
Maria Grazia Bernardini,Carlo Luciano Bianco,Letizia Caito,Maria Giovanna Dainotti,Roberto Guida,Remo Ruffini 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.5
Within the "fireshell" model, we define a "canonical GRB" light curve with two sharply different components: the proper-GRB (P-GRB), emitted when the optically thick fireshell of an electron-positron plasma originating from the phenomenon reaches transparency, and the afterglow, emitted due to the collision between the remaining optically thin fireshell and the circumburst medium (CBM). On the basis of the recent understanding of GRB970228 as the prototype for a new class of GRBs with "an occasional softer extended emission lasting tenths of seconds after an initial spikelike emission", we outline our "canonical GRB" scenario, originating from the gravitational collapse to a black hole, with special emphasis on the discrimination between "genuine" and "fake" short GRBs. Furthermore, we investigate how the GRB970228 analysis provides a theoretical explanation for the apparent absence of such a correlation for the GRBs belonging to this new class.
Accardo, Grazia,Frattini, Domenico,Ham, Hyung Chul,Yoon, Sung Pil Elsevier 2019 CERAMICS INTERNATIONAL Vol.45 No.7
<P><B>Abstract</B></P> <P>To improve the microstructural and electrochemical properties of gadolinium-doped ceria (GDC) electrolytes, materials co-doped with 0.5–2 mol% of lithium and cobalt oxides were successfully prepared in a one-step sol gel combustion synthesis route. Vegard's slope theory was used to predict the dopant solubility and the sintering behaviour. The charge and size of the added dopant influence the atom flux near the grain boundary with a change in the lattice parameter. In fact, compared to traditional multi grinding steps, sol gel combustion facilitates molecular mixing of the precursors and substitution of the dopant cations into the fluorite structure, considerably reducing the sintering temperature. Adding precursors of lithium and cobalt, as dopant, increases the GDC densification and reduces its traditional sintering temperature down to 1000–1100 °C, with an improvement of electrochemical properties. Impedance analysis showed that the addition of 2 mol% of lithium or 0.5 mol% of cobalt enhances the conductivity with a consequent improvement of cell performances. High total conductivities of 1.26·10<SUP>−1</SUP> S cm<SUP>−1</SUP> and 8.72·10<SUP>−2</SUP> S cm<SUP>−1</SUP> at 800 °C were achieved after sintering at 1000 °C and 1100 °C for <SUP>2</SUP>LiGDC and <SUP>0.5</SUP>CoGDC, respectively.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Accardo, Grazia,Frattini, Domenico,Moreno, Angelo,Yoon, Sung Pil,Han, Jong Hee,Nam, Suk Woo Elsevier Sequoia 2017 Journal of Power Sources Vol. No.
<P><B>Abstract</B></P> <P>Anode materials in Molten Carbonate Fuel Cells should have high creep resistance and good mechanical behavior to endure in high temperature-corrosive environments. In this work, zirconia nanoparticles (1–10% wt.) are added to NiAl anodes in order to investigate their effects on mechanical properties and single cell performances. Results show that nanoparticles strongly adhere to metal particles and bending strength increases from 6.08 to 11.33 kg<SUB>f</SUB> cm<SUP>−2</SUP> while creep strain is reduced from 7.55% to 3.25%. In the case of the anode with ZrO<SUB>2</SUB> 3% wt., the stable and high output voltage of 0.81 V at 150 mA cm<SUP>−2</SUP> is a promising result, compared to the literature. In addition, the solid contact angles between melted electrolyte and anode, for the NiAl reference sample and the ZrO<SUB>2</SUB> 3% wt. are 37.6° and 17°, respectively, showing the improved wettability of the modified anode. However, it seems to be a limit to the effective zirconia content as the contact angle of the anode with ZrO<SUB>2</SUB> 10% wt. is 58.1°, which indicates a low wetting ability. When zirconia content is too high, single cells have low performances due to high internal resistance and porosity reduction. The formation of a zirconate phase also occurs during operations.</P> <P><B>Highlights</B></P> <P> <UL> <LI> NiAl anodes with nano ZrO<SUB>2</SUB> are tested in MCFC single cell after characterization. </LI> <LI> Results show that nanoparticles improve mechanical and creep properties. </LI> <LI> The anode with ZrO<SUB>2</SUB> 3% wt. has the best performance over 1000 h operations. </LI> <LI> Post analysis shows zirconates formation at cathode for ZrO<SUB>2</SUB> contents over 5% wt. </LI> <LI> A high content of nanoparticles can diminish too much porosity and pore size. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Pizzoli, Giuliano,Lobello, Maria Grazia,Carlotti, Benedetta,Elisei, Fausto,Nazeeruddin, Mohammad K.,Vitillaro, Giuseppe,De Angelis, Filippo The Royal Society of Chemistry 2012 Dalton Transactions Vol.41 No.38
<P>We report a combined spectro-photometric and computational investigation of the acid–base equilibria of the N3 solar cell sensitizer [Ru(dcbpyH<SUB>2</SUB>)<SUB>2</SUB>(NCS)<SUB>2</SUB>] (dcbpyH<SUB>2</SUB> = 4,4′-dicarboxyl-2,2′ bipyridine) in aqueous/ethanol solutions. The absorption spectra of N3 recorded at various pH values were analyzed by Single Value Decomposition techniques, followed by Global Fitting procedures, allowing us to identify four separate acid–base equilibria and their corresponding ground state p<I>K</I><SUB>a</SUB> values. DFT/TDDFT calculations were performed for the N3 dye in solution, investigating the possible relevant species obtained by sequential deprotonation of the four dye carboxylic groups. TDDFT excited state calculations provided UV-vis absorption spectra which nicely agree with the experimental spectral shapes at various pH values. The calculated p<I>K</I><SUB>a</SUB> values are also in good agreement with experimental data, within <1 p<I>K</I><SUB>a</SUB> unit. Based on the calculated energy differences a tentative assignment of the N3 deprotonation pathway is reported.</P> <P>Graphic Abstract</P><P>The acid–base properties of the N3 solar cell sensitizer are investigated, identifying four separate equilibria and determining the corresponding p<I>K</I><SUB>a</SUB>s. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2dt31340e'> </P>
Alessia Chini,Michele Manigrasso,Grazia Cantore,Rosa Maione,Marco Milone,Francesco Maione,Giovanni Domenico De Palma 대한소화기내시경학회 2022 Clinical Endoscopy Vol.55 No.2
Colorectal cancer is an important cause of morbidity and mortality worldwide. Optical colonoscopy (OC) is widely accepted as thereference standard for the screening of colorectal polyps and cancers, and computed tomography colonography (CTC) is a validalternative to OC. The purpose of this review was to assess the diagnostic accuracy of OC and CTC for colorectal lesions. A literaturesearch was performed in PubMed, Embase, and Cochrane Library, and 18 articles were included. CTC has emerged in recent years asa potential screening examination with high accuracy for the detection of colorectal lesions. However, the clinical application of CTCas a screening technique is limited because it is highly dependent on the size of the lesions and has poor performance in detectingindividual lesions <5 mm or flat lesions, which, although rarely, can have a malignant potential.