Publications by authors named "Jihyeon Park"

8 Publications

  • Page 1 of 1

Counter-rotatable dual cinchona quinuclidinium salts and their phase transfer catalysis in enantioselective alkylation of glycine imines.

Chem Commun (Camb) 2021 Jul;57(55):6816-6819

School of Chemistry and Biochemistry, Yeungnam University, 280 Daehak-Ro, Gyeongsan, Gyeongbuk 38541, Republic of Korea.

Dual cinchona quinuclidinium salts with a diphenyl ether linker were synthesized and used as powerful asymmetric phase transfer catalysts in the α-alkylation of imines of glycine and alanine ester with 0.01-0.1 mol% loading (17 examples, 92-99% ee). Skewed conformers of dual quinuclidiniums at TS were proposed to rationalize their high efficiency via DFT calculations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/d1cc02785aDOI Listing
July 2021

Daily Life Changes and Life Satisfaction among Korean School-Aged Children in the COVID-19 Pandemic.

Int J Environ Res Public Health 2021 03 23;18(6). Epub 2021 Mar 23.

Department of Child Development and Family Studies, College of Human Ecology, Seoul National University, Seoul 08826, Korea.

The recent COVID-19 pandemic has been disrupting the daily lives of people across the world, causing a major concern for psychological well-being in children. This study aimed to examine (1) how life satisfaction and its potential predictors have been affected by the pandemic among school-aged children in Korea, and (2) which factors would predict their life satisfaction during the pandemic. We surveyed 166 fourth-graders in the Seoul metropolitan area to assess their psychological well-being and potentially related variables during the pandemic. The data were compared with those available from two pre-COVID-19 surveys, the 2018 Korean Children and Youth Panel Survey ( = 1236) and the 2019 Korean Children and Youth Well-being Index Survey ( = 334). Higher levels of stress were observed in children during the COVID-19 pandemic; however, the level of their life satisfaction remained unchanged when compared with data from the pre-COVID-19 surveys. The pandemic also affected peer relationship quality and susceptibility to smartphone addiction, but not perceived parenting style nor academic engagement. Interestingly, peer relationship quality no longer predicted life satisfaction during the pandemic; perceived parenting styles and parent-child conversation time predicted life satisfaction. The results suggest a central role of parent-child relationship in supporting the psychological well-being of school-aged children during the pandemic.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/ijerph18063324DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8004811PMC
March 2021

Ultra-low concentration of total organic carbon in ultrapure water using ion-exchange resin embedding silanized magnetic nanoparticles.

J Environ Sci (China) 2020 Jun 18;92:11-17. Epub 2019 Dec 18.

Korea Institute of Industrial Technology, 89 Yangdaegiro-gil, Ipjang-myeon, Cheonan-si 31056, South Korea. Electronic address:

Regeneration of pure water is an important issue not only for the healthy life but also for the fine control of precise processes in various industries. One important issue in ultra-high purified water is to reduce the amount of total organic carbon (TOC). Herein, we introduce a new approach to reduce the TOC using the surface silanized nanoparticles, in which the magnetic nanoparticles (mNPs) are silanized and then complexed with ion exchange resin (IER) beads. The FeO mNPs are surface modified by using high concentrated vinyltrimethoxysilane (VTMS) and then adhered on the surface of IER beads. The surface modified mNPs have a thick-shell of polysiloxane layer varying from 5 to 22 nm depending on the amount of VTMS used, which leads the significant increase of specific surface area. The IER beads embedding VTMS-silanized mNPs achieves about 7 μg/L of the TOC level in ultrapure water system, which is two orders less than 228 μg/L of the feeding water and one order less than 96 μg/L from the system using pristine IER beads. This result is mainly attributed to the polysiloxane layer forming broccoli-like surface structure and some part by the vinyl group of VTMS exposed to the amines in the water.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jes.2019.11.023DOI Listing
June 2020

RGO-Coated TiO Microcones for High-Rate Lithium-Ion Batteries.

ACS Omega 2018 Aug 30;3(8):10205-10210. Epub 2018 Aug 30.

Department of Chemistry and Chemical Engineering, Inha University, 22212 Incheon, South Korea.

Reduced graphene oxide (RGO)-coated TiO microcones have been synthesized via simple anodization and cyclic voltammetry for use in lithium-ion batteries (LIBs). Microcones had a perpendicularly oriented hollow core, an anatase structure, and a high surface area, allowing higher capacity than other nanosized TiO structures. TiO has low electrical conductivity, leading to the limitation of fast charging and high capacity; however, this was improved by the application of an RGO coating in this work. As anode materials of LIB, the obtained RGO microcone showed a capacity of 157 mAh g at 10C (fully charged within ∼360 s) and sustained 1000 cycles with only 0.02% capacity fading per cycle. The capacity was 1.5 times higher than that of conventional microcone. We speculated that the decrease in the charge-transfer resistance ( ) played a crucial role in increasing the capacity with fast charging.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsomega.8b00926DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6644754PMC
August 2018

A comparison of biomechanical workload between smartphone and smartwatch while sitting and standing.

Appl Ergon 2019 Apr 20;76:105-112. Epub 2018 Dec 20.

The Human and Safety Engineering Laboratory, Department of Industrial Engineering, Pusan National University, Busan, 46241, Republic of Korea. Electronic address:

Increasing concerns about musculoskeletal disorders in the upper back arising from excessive daily use of the smartwatch have been widely validated by the rising prevalence of discomfort. This study explored the smartwatch as a potential ergonomic intervention over the smartphone. Fourteen healthy participants completed five tasks (application setting, calling, message typing, message checking and vocal message entry) with smartphone and smartwatch in both sitting and standing postures. The neck-shoulder kinematics and muscle activation levels were monitored to assess the effects of the tasks, devices, and postures. The results indicated greater head flexion, head rotation and shoulder abduction and greater muscle activities for smartwatch use compared to smartphone use, but the performance measure (i.e., elapsed time) was superior for smartwatch use in all tasks except message typing. Collectively, only short and simple tasks such as message checking and application setting should be conducted with the smartwatch.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.apergo.2018.11.009DOI Listing
April 2019

Genomic characterization of malonate positive serotype O:2, sequence type 64 strains, isolated from clinical, food, and environment samples.

Gut Pathog 2018 10;10:11. Epub 2018 Mar 10.

1Center of Food Safety and Applied Nutrition, U. S. Food and Drug Administration, Laurel, MD 20708 USA.

Background: Malonate utilization, an important differential trait, well recognized as being possessed by six of the seven species is thought to be largely absent in (Csak). The current study provides experimental evidence that confirms the presence of a malonate utilization operon in 24 strains of sequence type (ST) 64, obtained from Europe, Middle East, China, and USA; it offers explanations regarding the genomic diversity and phylogenetic relatedness among these strains, and that of other strains.

Results: In this study, the presence of a malonate utilization operon in these strains was initially identified by DNA microarray analysis (MA) out of a pool of 347 strains obtained from various surveillance studies involving clinical, spices, milk powder sources and powdered infant formula production facilities in Ireland and Germany, and dried dairy powder manufacturing facilities in the USA. All ST64 strains tested could utilize malonate. Zebrafish embryo infection studies showed that ST64 strains are as virulent as other species. Parallel whole genome sequencing (WGS) and MA showed that the strains phylogenetically grouped as a separate clade among the Csak species cluster. Additionally, these strains possessed the Csak O:2 serotype. The nine-gene, ~ 7.7 kbp malonate utilization operon was located in these strains between two conserved flanking genes, and Plasmidotyping results showed that these strains possessed the virulence plasmid pESA3, but in contrast to the USA ST64 Csak strains, ST64 Csak strains isolated from sources in Europe and the Middle East, did not possess the type six secretion system effector gene.

Conclusions: Until this investigation, the presence of malonate-positive Csak strains, which are associated with foods and clinical cases, was under appreciated. If this trait was used solely to identify strains, many strains would likely be misidentified. Parallel WGS and MA were useful in characterizing the total genome content of these Csak O:2, ST64, malonate-positive strains and further provides an understanding of their phylogenetic relatedness among other virulent strains.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s13099-018-0238-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5845375PMC
March 2018

Draft Genome Sequences of Enterotoxigenic Strains Obtained from Powdered Infant Formula.

Genome Announc 2017 Feb 23;5(8). Epub 2017 Feb 23.

Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Laurel, Maryland, USA

We introduce the draft genome sequences of five enterotoxigenic strains: Bc 12, Bc 67, Bc 111, Bc 112, and Bc 113, which were obtained from powdered infant formula. The genome sizes of the strains ranged from 5.5 to 5.8 Mb, and the G+C contents were ~35.2%.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1128/genomeA.01644-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5323619PMC
February 2017

[A case of cap polyposis complicated with idiopathic retroperitoneal fibrosis].

Korean J Gastroenterol 2011 Nov;58(5):275-9

Department of Internal Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.

An optimal treatment for cap polyposis has not been established. Several treatment approaches, including anti-inflammatory agents, antibiotics, immunomodulators, and endoscopic therapy have been described. Surgical resection of the affected colon and rectum may be indicated for patients with persistent disease. Repeat surgery is indicated in cases of recurrence after surgery. However, symptomatic polyposis may still recur, and spontaneous resolution of cap polyposis is possible. We report a case of recurrent cap polyposis complicated with retroperitoneal fibrosis after inadequate low anterior resection with a positive resection margin. Surgical approaches for the treatment of cap polyposis should be carefully considered before treatment.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4166/kjg.2011.58.5.275DOI Listing
November 2011
-->