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Enhancement of NOx photo-oxidation by Fe-doped TiO2 nanoparticles
Adriana Martinez-Oviedo,Schindra Kumar Ray,Gobinda Gyawali,Vicente Rodriguez-Gonzalez,Soo Wohn Lee 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.3
Microwave hydrothermal-assisted sol-gel method was employed to synthesize the Fe doped TiO2 photocatalyst. Themorphological analysis suggests anatase phase nanoparticles of ~20 nm with an SBET area of 283.99 m2/g. The doping of Feions in TiO2 created oxygen vacancies and Ti3+ species as revealed through the XPS analysis. The reduction of the band gap(3.1 to 2.8 eV) is occurred by doping effect. The as-prepared photocatalyst was applied for removal of NOx under solar lightirradiation. The doping of Fe in TiO2 facilitates 75 % of NOx oxidation efficiency which is more than two-fold enhancementthan the TiO2 photocatalyst. The possible reason of enhancement is associated with high surface area, oxygen vacancy, andreduction of the band gap. Also, the low production of toxic intermediates, NO2 gas, is further confirmed by Combustion IonChromatography. The mechanism related NOx oxidation by the doped photocatalyst is explained in this study.
Lu, Ning,Wang, Jinguo,Oviedo, uan Pablo,Lian, Guoda,Kim, Moon Jea Korean Society of Microscopy 2015 Applied microscopy Vol.45 No.4
Transition metal dichalcogenides (TMDs) are a class of two-dimensional (2D) materials that have attracted growing interest because of their promising applications. The properties of TMDs strongly depend on the crystalline structure and the number and stacking sequence of layers in their crystals and thin films. Though electrical, mechanical, and magnetic studies of 2D materials are being conducted, there is an evident lack of direct atom-by-atom visualization, limiting insight on these highly exciting material systems. Herein, we present our recent studies on the characterization of 2D layered materials by means of aberration corrected scanning transmission electron microscopy (STEM), in particular via high angle annular dark field (HAADF) imaging. We have identified the atomic arrangements and defects in 2H stacked TMDs, 1T stacked TMDs, distorted 1T stacked TMDs, and vertically integrated heterojunctions of 2D TMDs crystals.
Tiantian (Nicole) Chen,Oscar Oviedo-Trespalacios,N.N. Sze,Sikai Chen 대한교통학회 2023 대한교통학회 학술대회지 Vol.88 No.-
Use of ride-hailing mobile apps has surged and reshaped the taxi industry. These apps allow real-time taxi-customer matching of taxi dispatch system. However, there are also increasing concerns for driver distractions as a result of these ride-hailing systems. This study aims to investigate the effects of distractions by different ride-hailing systems on the driving performance of taxi drivers using the driving simulator experiment. In this investigation, fifty-one male taxi drivers were recruited. During the experiment, the road environment (urban street versus motorway), driving task (free-flow driving versus car-following), and distraction type (no distraction, auditory distraction by radio system, and visual-manual distraction by mobile app) were varied. Repeated measures ANOVA and random parameter generalized linear models were adopted to evaluate the distracted driving performance accounting for correlations among different observations of a same driver. Results indicate that distraction by mobile app impairs driving performance to a larger extent than traditional radio systems, in terms of the lateral control in the free-flow motorway condition and the speed control in the free-flow urban condition. In addition, for car-following task on urban street, compensatory behaviour (speed reduction) is more prevalent when distracted by mobile app while driving, compared to that of radio system. Additionally, no significant difference in subjective workload between distractions by mobile app and radio system were found. Several driver characteristics such as experience, driving records, and perception variables also influence driving performances. The findings are expected to facilitate the development of safer ride-hailing systems, as well as driver training and road safety policy.
Pedro Roa-Sanchez,Pamela Bido,Jairo Oviedo,Hans-Jürgen Huppertz,Herwin Speckter,Peter Stoeter 대한파킨슨병및이상운동질환학회 2021 Journal Of Movement Disorders Vol.14 No.2
ObjectiveaaTo determine the volume changes in gray and white matter during a long-term follow-up in patients suffering frompantothenate kinase-associated neurodegeneration (PKAN). MethodsaaMagnetic resonance imaging was repeated in 13 patients and 14 age-matched controls after a mean interval of morethan 7 years. T1-weighted sequences were evaluated by fully automated atlas-based volumetry, compared between groups andcorrelated with disease progression. ResultsaaThe patients did not show generalized cerebral atrophy but did show a significantly faster volume reduction in theglobus pallidus during follow-up (between -0.96% and -1.02% per year, p < 0.05 adjusted for false discovery rate) than controls,which was significantly related to the progression in their dystonia scores (p = 0.032). ConclusionaaThe volume loss in the globus pallidus over time—together with the accumulation of iron known as the “tiger’seye”—supports the pathophysiologic concept of this nucleus as a center of inhibition and its severe malfunction in PKAN.
Modified blue TiO2 nanostructures for efficient photo-oxidative removal of harmful NOx gases
Hao Huy Nguyen,GYAWALI GOBINDA,Adriana Martinez-Oviedo,Hoang Phuc Nguyen,이수원 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.9
Blue TiO2 nanostructures were produced via Lithium/ethylenediamine (Li/EDA) reduction method and applied for photo-oxidative removal of harmful NOx gases under simulated solar light irradiation. Blue TiO2 possesses some unique physicochemical properties such as enhanced visible-light absorption, superficial defects or oxygen vacancies, and the evolution of Ti3+ species. Moreover, the photoluminescence spectra (PL) revealed the efficient separation of photoinduced electron-hole pairs in the modified blue TiO2 nanostructures, enhancing their photocatalytic activities. The results indicated that the blue TiO2 nanostructures exhibited the highest performance towards photo-oxidation of NOx gases, with an efficiency of 72.6% under simulated solar light irradiation
The Inter-generic Fungicidal Activity of Xanthophyllomyces dendrorhous
Marcelo Baeza,Oriana Flores,Mario Carrasco,Juan Manuel Rozas,Vicente Oviedo,Salvador Barahona,Víctor Cifuentes 한국미생물학회 2010 The journal of microbiology Vol.48 No.6
In this study, the existence of intra-specific and inter-generic fungicidal activity in Xanthophyllomyces dendrorhous and Phaffia rhodozyma strains isolated from different regions of the earth was examined. Assays were performed under several culture conditions, showing that all the analyzed X. dendrorhous and P. rhodozyma strains have killing activity against Kloeckera apiculata, Rhodotorula sloffiae, and R. minuta. This activity was greater in rich media at a pH from 4.6 to 5.0. Extracellular protein extracts with fungicidal activity were obtained from cultures of all strains, and their characterization suggested that a protein of ∼33kDa is the antifungal factor. According to peptide mass fingerprinting and an analysis of the results with the MASCOT search engine, this protein was identified as an aspartic protease. Additionally, extrachromosomal double-stranded DNA elements (dsDNAs) were observed in all X. dendrorhous and P. rhodozyma strains. Although there is a high variability, two dsDNAs of 5.4 and 6.8 kb are present in all strains.