산소원자를 제거한 TiO₂ 나노입자 특성의 양자화학 계산 연구

김선경,고경철,이진용,Francesc Illas 대한환경공학회 2019 대한환경공학회 학술발표논문집 Vol.2019 No.12

When Anatase Nanoparticles Become Bulklike: Properties of Realistic TiO₂ Nanoparticles in the 1–6 nm Size Range from All Electron Relativistic Density Functional Theory Based Calculations

Lamiel-Garcia, Oriol,Ko, Kyoung Chul,Lee, Jin Yong,Bromley, Stefan T.,Illas, Francesc American Chemical Society 2017 Journal of chemical theory and computation Vol.13 No.4

<P>All electron relativistic density functional theory (DFT) based calculations using numerical atom-centered orbitals have been carried out to explore the relative stability, atomic, and electronic structure of a series of stoichiometric TiO2 anatase nanoparticles explicitly containing up to 1365 atoms as a function of size and morphology. The nanoparticles under scrutiny exhibit octahedral or truncated octahedral structures and span the 1-6 nm diameter size range. Initial structures were obtained using the Wulff construction, thus exhibiting the most stable (101) and (001) anatase surfaces. Final structures were obtained from geometry optimization with full relaxation of all structural parameters using both generalized gradient approximation (GGA) and hybrid density functionals. Results show that, for nanoparticles of a similar size, octahedral and truncated octahedral morphologies have comparable energetic stabilities. The electronic structure properties exhibit a clear trend converging:to the bulk values as the size of the nanoparticles increases but with a marked influence of the density functional employed. Our results suggest that electronic structure properties, and hence reactivity, for the largest anatase nanoparticles considered in this study will be similar to those exhibited by even larger mesoscale particles or by bulk systems. Finally, we present compelling evidence that anatase nanoparticles become effectively bulklike when reaching a size of similar to 20 nm diameter.</P>

Performance of a modified hybrid functional in the simultaneous description of stoichiometric and reduced TiO₂ polymorphs

Ko, Kyoung Chul,Lamiel-Garcí,a, Oriol,Lee, Jin Yong,Illas, Francesc The Royal Society of Chemistry 2016 Physical chemistry chemical physics Vol.18 No.17

<P>Conventional density functionals with either the local density approximation (LDA) or the generalized gradient approximation (GGA) form of the exchange-correlation potential fail to describe the electronic structure of a large number of metal oxides. Both the LDA and the GGA grossly underestimate the band gaps of these materials which severely affect the description of oxygen vacancy point defect states in reduced samples. To find a pragmatic approach to simultaneously and accurately describe the atomic and electronic structures of the most common TiO2 polymorphs, we explore the effect of the percentage of exact, non-local, Fock exchange on the electronic structure of stoichiometric rutile and anatase. From these results, a modified hybrid functional is proposed to properly describe the atomic structures, formation enthalpies and electronic structures of rutile and anatase and, at the same time, the results of reduced samples are also in good agreement with the available experimental results. The present approach can be safely used to accurately describe numerous TiO2 based materials containing defects or realistic nanoparticles for which the required large unit cells or system sizes hinder the use of GW related techniques.</P>

Single oxygen vacancies of (TiO₂)₃₅ as a prototype reduced nanoparticle: implication for photocatalytic activity

Kim, Sunkyung,Ko, Kyoung Chul,Lee, Jin Yong,Illas, Francesc The Royal Society of Chemistry 2016 Physical chemistry chemical physics Vol.18 No.34

<P>Titanium dioxide (TiO2), as a semiconductor metal oxide, has been one of the most popular materials studied in the field of photocatalysis. In the present study, the properties of single oxygen vacancies of (TiO2)(35), a prototype of an anatase nanoparticle, were investigated by DFT calculations. (TiO2)(35) is the minimum sized model (similar to 2 nm) for a bipyramidal nanoparticle with anatase phase and eight {101} facets. All the available oxygen vacancies at various sites according to position, coordination number, and distance from the center atom were examined. The geometric, energetic and electronic properties of the reduced TiO2 clusters were analyzed by hybrid DFT functionals with different Hartree-Fock exchange ratios (0, 12.5 and 25%). It was found that the structure of pristine (TiO2)(35) is somewhat different from the bulk lattice, with a relatively high surface to volume ratio. Moreover, the particular highly (three)-coordinated oxygen atom is energetically the most favorable for oxygen vacancy formation from the nanoparticle mainly due to its substantially high relaxation energy. TiO2 nanoparticles have low oxygen vacancy formation energy and narrow band gap because of their defect states, and can be utilized as an efficient photocatalyst material.</P>

Evaluation of selection program by assessing the genetic diversity and inbreeding effects on Nellore sheep growth through pedigree analysis

Illa Satish Kumar,Gollamoori Gangaraju,Nath Sapna 아세아·태평양축산학회 2020 Animal Bioscience Vol.33 No.9

Objective: The main objectives of the present study were to assess the genetic diversity, population structure and to appraise the efficiency of ongoing selective breeding program in the closed nucleus herd of Nellore sheep through pedigree analysis. Methods: Information utilized in the study was collected from the pedigree records of Livestock Research Station, Palamaner during the period from 1989 to 2016. Genealogical parameters like generation interval, pedigree completeness, inbreeding level, average relatedness among the animals and genetic conservation index were estimated based on gene origin probabilities. Lambs born during 2012 and 2016 were considered as reference population. Two animal models either with the use of Fi or ΔFi as linear co-variables were evaluated to know the effects of inbreeding on the growth traits of Nellore sheep. Results: Average generation interval and realized effective population size for the reference cohort were estimated as 3.38±0.10 and 91.56±1.58, respectively and the average inbreeding coefficient for reference population was 3.32%. Similarly, the effective number of founders, ancestors and founder genome equivalent of the reference population were observed as 47, 37, and 22.48, respectively. Fifty per cent of the genetic variability was explained by 14 influential ancestors in the reference cohort. The ratio fe/fa obtained in the study was 1.21, which is an indicator of bottlenecks in the population. The number of equivalent generations obtained in the study was 4.23 and this estimate suggested the fair depth of the pedigree. Conclusion: Study suggested that the population had decent levels of genetic diversity and a non-significant influence of inbreeding coefficient on growth traits of Nellore lambs. However, small portion of genetic diversity was lost due to a disproportionate contribution of founders and bottlenecks. Hence, breeding strategies which improve the genetic gain, widens the selection process and with optimum levels of inbreeding are recommended for the herd.

Physical, Psychological and Social Benefits of Participation in Youth Sports for Children Ages 9-12 Years

( Illa R. Haley ),( Seung Ho Chang ) 한국체육학회 2021 International journal of human movement science Vol.15 No.2

Youth sports differ from physical activity due to the fact that they are organized and help teach life lessons through interaction with other children, teach responsibility, and commitment. It has grown vastly over the years ranging in multiple sports and many studies found that participating in youth sports is beneficial to a developing child and it could potentially help prevent the child obesity pandemic. For example, youth sport programs can provide children and youth with opportunities to be physically active such as organized practice, training and scrimmage which will lead to improved physical health. In addition, youth sport programs have long been considered significant to children and youth’s development psychosocial aspects (e.g., cooperation, teamwork, discipline, leadership, and self-control). Furthermore, females who participate in youth sport have become a particular interest to sports science, motor development, and youth sport researchers. Therefore, the purpose of this paper was to review the literature on physical, psychological, and social benefits of children participating in youth sports. The particular age range that was focused on in this paper was children ages 9-12 who participate in youth sports.

Evaluation of models for estimation of genetic parameters for post-weaning body measurements and their association with yearling weight in Nellore sheep

Illa Satish Kumar,Gollamoori Gangaraju,Nath Sapna 아세아·태평양축산학회 2024 Animal Bioscience Vol.37 No.3

Objective: The objective of this study was to obtain (co) variance components and genetic parameter estimates for post-weaning body measurements such as body length (BL), height at withers (HW), and chest girth (HG) recorded at six (SBL, SHW, and SHG), nine (NBL, NHW, and NHG) and twelve (YBL, YHW, and YHG) months of age along with yearling weight (YW) in Nellore sheep maintained at livestock research station, Palamaner, Andhra Pradesh, India and also the association among body measurements with YW was studied. Methods: Data on 2,076 Nellore sheep (descended from 75 sires and 522 dams) recorded between 2007 and 2016 (10 years) were utilized in the study. Lambing year, sex of lamb, season of lambing and parity of dam were included in the model as fixed effects and ewe weight was kept as a covariate. Analyses were conducted with six animal models with different combinations of direct and maternal genetic effects using restricted maximum likelihood procedure. Best model for each trait was determined based on Akaike’s information criterion. Results: Moderate estimates of direct heritability were obtained for the studied traits viz., BL (0.02 to 0.24), HW (0.31 to 0.49), and CG (0.08 to 0.35) and their corresponding maternal heritability estimates were in the range of 0.00 to 0.07 (BL), 0.13 to 0.17 (HW), and 0.07 to 0.13 (CG), respectively. Positive direct genetic and phenotypic correlations among the traits and they ranged from 0.07 (YBL-YW) to 0.99 (SBL-SHG, SHG-YW, and NBL-YBL) and 0.01 (SBL-YBL) to 0.99 (NBL-NHG), respectively. Further, the genetic correlations among all the body measurements and YW were positive and ranged from 0.07 (YW and YBL) to 0.99 (YW and SHG). Conclusion: There was a strong association of chest girth at six months with YW. Further, it is indicated that moderate improvement of post-weaning body measurements in Nellore sheep would be possible through selection.

A review of wireless access vehicular environment multichannel operational medium access control protocols: Quality-of-service analysis and other related issues

Rasool, Illa Ul,Zikria, Yousaf Bin,Kim, Sung Won SAGE Publications 2017 International journal of distributed sensor networ Vol.13 No.5