Synergistic effect of UV and <small>L</small>-ascorbic acid on the reduction of graphene oxide: Reduction kinetics and quantum chemical simulations

Go, Su-Hyeon,Kim, Hyungjun,Yu, Jaesang,You, Nam-Ho,Ku, Bon-Cheol,Kim, Young-Kwan Elsevier 2018 Solid state sciences Vol.84 No.-

<P><B>Abstract</B></P> <P>A photochemical strategy for eco-friendly reduction of graphene oxide (GO) was developed by using <SMALL>L</SMALL>-ascorbic acid (L-AA) as a photosensitive reducing agent. L-AA was excited and oxidized with deprotonation by UV irradiation (254 nm) and the proton coupled electron transfer induces chemical reduction of GO. This photochemical process is quite eco-friendly and scalable, and the reduction kinetics and degree of GO were highly enhanced. To understand the improved reduction power by UV light, the redox properties of L-AA in the ground and excited states were characterized by using quantum chemical simulations. Based on the results, we clearly demonstrated the mechanism how UV irradiation considerably enhances the reducing power of L-AA for the reduction of GO.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The enhancement of reducing power of <SMALL>L</SMALL>-ascorbic acid by UV irradiation. </LI> <LI> Theoretical investigation of UV-enhanced reducing power of <SMALL>L</SMALL>-ascorbic acid. </LI> <LI> The reduction of graphene oxide by using <SMALL>L</SMALL>-ascorbic acid under UV irradiation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

유기용제노출이 직업적 청력손실에 미치는 영향

이지호,고영주,이헌,강정학,유철인,이충렬,김양호 大韓産業醫學會 2000 대한직업환경의학회지 Vol.12 No.4

목적 : 산업 장에서 노출되는 유기용제가 청력역치에 어떠한 영향을 미치는가를 5년 동안의 추적조사를 통하여 파악하고자 하였다. 방 법 : 유기용제와 소음에 동시에 노출된 근로자 43명과 소음노출수준, 연령, 근무경력을 짝짓기 한소음노출군을 대상으로 문진과 이경검사, 소음노출 수준, 유기용제노출수준을 조사하였다. 결과 : 1. 전체 근로자의 각 주파수별 청력역치 변화양상에서 500Hz∼2000Hz에서는 추적기간 동 소음동안 현저한 변화가 없었고, 4000Hz 및 8000Hz에서는 역치가 증가하는 경향을 나타내었다. 2.유기용제와 소음에 동시에 노출된군에서 소음 노출군에 비해 4000Hz 이상에서 청력역치가 높게 나타났으나, 통계적인 유의성은 없었다(p(0.05). 3.반복측정 분산분석 법으로 각 주파수별 평균청력 역치의 연차적 변화에 미치는 영향을 분석한 결과 유기용제 노출은 통계적으로 유의한 영향이 없었으나(p)0.05), 소음노출수준은 250Hz, 2000Hz 및 4000Hz에서, 연령은 250Hz와 500Hz에서 통계학적으로 유의한 영향을 미치는 것으로 나타났다(p(0.05). 4.소음노출군파 동시노출군 각각에서의 청력역치 변화량을 paired t-test로 비교한 결과 250Hz∼4000Hz에서는 통계학적 유의성이 없었으며(p(0.1), 8000Hz에서만 경계치 (p=0.0884)의 유의성을 나타내었다. 5.요인들의 영향을 보정한 상태에서 관찰하기 위해 관찰기간동안의 청력역치변화량을 종속변수로 두고 일반선형모형을 이용하여 주파수별로 관찰한 결과 8000Hz에서만 모델에 통계학적 유의성이 있었으며 (p(0.05), 여기서 소음노출수준이 통계학적으로 유의한 영향을 미치는 것으로 나타났고(p(0.05), 유기용제노출은 경 계수준이 었다(p=0.087). 결론 : 청력에 대한 유기용제의 영향이 소음과 연령에 비해 상대적으로 미미하여 명확한 결론에 이르지는 못하였으나, 다소 영향이 있는 것으로 생각되어 유기용제의 영향에 대한 추가연구가 필요할 것으로 판단된다. 또한 보다 효과적인 근로자들의 청력관리를 위해서는 소음 외 산업 장에서 동시에 노출되는 여러 유해물질들을 고려하여야 할 것이다. Objectives : This study was to evaluate the impacts of simultaneous exposure to noise and mixed solvents on workers'hearing threshold level (HTL) over five-year period. Methods : The study was conducted by interview and annual audiometric test on workers in ship building industry from 1994 to 1998. The cases(workers who exposed to noise and mixed solvent simultaneously) were 43 male workers and controls (workers who exposed to nolle) were selected by matching method with regard to age, sex, carrier, and noise exposure level. To assess the impacts of solvent exposure on hearing threshold level, with considering other factors, general liner model was used. Results : 1. The audiogram of all subjects showed typical sensorineural hearing loss pattern. The mean HTLe were increased at high frequency (4000HB and 8000Hz) for study period. 2. The HTLs of cases were more increased than those of controls at high frequencies (4000Hz and 8000Hz), but there was not statlstical significance. 3. The impact of age on the HTL was statistically significant at 250Hz and 500Hz (p(0.05), and the impact of noise on the HTL was statistically significant at 250Hz, 2000Hz and 4000Hz (p(0.05), but the impact solvent exposure on the HTL was not significant. 4. The changes in HTLs of cases were higher than those of controls at high frequency, there were not statistical significance at 4000Hz, but only at 8000Hz (p=0.087). 5. Statistical analysis of the general linear model implicated that the changes in HTL was impacted by noise exposure bevel significantly (p=0.031) and Impacted by solvent exposure weakly (p=0.087) at 8000Hz. Conclusions : The results of this study suggest that workers who simultaneously exposed to noise and mixed solvent were at risk for more affected HTL than those exposed to noise exposure only, but we could not find definitive evidence. Further detailed studies must be made in large number of workers.

Regulatory Effect of Matcha Green Tea on Fine Dust-Exposed Cytotoxicity in Respiratory System

Jong Min Kim,Jong Hyun Moon,Min Ji Kim,Hyo Lim Lee,Hye Rin Jeong,Min Ji Go,Tae Yoon Kim,Seung Gyum Joo,Jong Cheol Kim,Ho Jin Heo 한국식품영양과학회 2021 한국식품영양과학회 학술대회발표집 Vol.2021 No.10

This study was performed to evaluate the protective effect of matcha green tea on particulate matter (PM)2.5-indued nasal and pulmonary cytotoxicity. The matcha green tea increased the cell viability and inhibited the ROS production in PM2.5-induced cytotoxicity in nasal RPMI2650 and pulmonary A549 cells. The matcha green tea regulated the expression of apoptosis, such as p-Akt, BCl-2, caspase-3, caspase-1 and HO-1, and inflammation, such as TLR4, TLR4 and Nrf2, in PM2.5-indued RPMI2650 cells. In addition, the matcha green tea showed regulatory effect of the apoptosis and inflammatory effect by increasing the BCl-2 and suppressing the caspase-3, TLR4, TNF-α and COX-2 in A549 cells. In addition, the matcha green tea suppressed antioxidant deficits by regulating the reduced GSH contents, SOD activities and MDA levels, and ameliorated the mitochondrial dysfunction by regulating the mitochondrial ROS production, mitochondrial membrane potential and ATP contents in pulmonary tissue. Ultimately, consumption of matcha green tea down-regulated the inflammatory proteins such as TNF-α, p-JNK, p-IκB-α, p-NF-κB and COX-2 in lung tissue.

지구성 트레이닝이 골격근 성장 유도 인자에 미치는 영향

고영호 ( Go Yeong Ho ),윤정수 ( Yun Jeong Su ),백인호 ( Baeg In Ho ),김재철 ( Kim Jae Cheol ) 한국운동영양학회 2002 Physical Activity and Nutrition (Phys Act Nutr) Vol.6 No.3

It was the aim of this study to investigate the expression of IGF-Ⅰ mRNA in the different fiber type and contractile property of skeletal muscle by endurance training. The male Sprague-Dawley rats underwent the treadmill running at the 55% of VO2 max (20m/min, 10°, 90min/day, 5days/week) during the 2, 4 and 8 weeks respectively. The expression of IGF-Ⅰ mRNA in gastrocnemius and soleus muscles were examined by quantitative Northern blotting. In the gastrocnemius and soleus IGF-Ⅰ mRNA level were increased after 2 weeks and 4 weeks endurance training and after 8weeks gradually decreased but higher than control group. These results indicate that the high expression of IGF-Ⅰ mRNA by endurance training may be contributing to the hypertrophy and regeneration response via the mobilization of satellite cells to provide increases in muscle DNA.

Genome-wide association study (GWAS) in pepper using a core collection

Hea-Young Lee,Ho-Cheol Go,On-Suk Heo,Jin-Kyung Kwon,Byoung-Cheorl Kang 한국육종학회 2015 한국육종학회 심포지엄 Vol.2015 No.07

GWAS (Genome-wide association study) provides a useful to associate phenotypic variation to genetic variation. It has emerged as a powerful approach for identifying genes underlying complex diseases or morphological traits at an unprecedented rate. Despite benefits, there are only a few examples applied in crop plants due to lack of effective genotyping techniques and well prepared resources for developing high density haplotype maps. In this study, 350 core accessions selected from almost 5,000 Capsicum accessions were used for GWAS. We are planning to construct a high-density haplotype map using GBS platform and perform GWAS for various agronomic traits including fruit traits and metabolites related to pungency to identify genes controlling the traits. These results will not only provide a list of candidate loci but also a powerful tools for finding genetic variants that can be directly used for crop improvement and deciphering the genetic architecture of complex traits.

Benchmarks of subcriticality in accelerator-driven system at Kyoto University Critical Assembly

Cheol Ho Pyeon,Masao Yamanaka,김송현,Thanh-Mai Vu,TOMOHIRO ENDO,Willem Fredrik G. Van Rooijen,GO CHIBA 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.6

Basic research on the accelerator-driven system is conducted by combining 235U-fueled and 232Th-loaded cores in the Kyoto University Critical Assembly with the pulsed neutron generator (14 MeV neutrons) and the proton beam accelerator (100 MeV protons with a heavy metal target). The results of experimental subcriticality are presented with a wide range of subcriticality level between near critical and 10,000 pcm, as obtained by the pulsed neutron source method, the Feynman-α method, and the neutron source multiplication method.

Temperature-controlled helical inversion of asymmetric triphenylamine-based supramolecular polymers; difference of handedness at the micro- and macroscopic levels

Go, Misun,Choi, Heekyoung,Kim, Ka Young,Moon, Cheol Joo,Choi, Yeonweon,Miyake, Hiroyuki,Lee, Shim Sung,Jung, Sung Ho,Choi, Myong Yong,Jung, Jong Hwa The Royal Society of Chemistry 2019 Organic chemistry frontiers Vol.6 No.8

<P>This study describes the temperature-controlled helicity inversion of supramolecular polymers based on <I>N</I>-triphenylamines (TPAs) bearing different numbers of d-alanine and/or glycine moieties. Despite chiral branching differences, the three investigated TPAs form helical supramolecular polymers <I>via</I> a typical nucleation-elongation model, characteristic of a cooperative assembly. The supramolecular polymer TPA-3, composed of symmetric tri-alanine segments, was more thermodynamically stable compared with TPA-1 and TPA-2, which had one or two alanine segments. More interestingly, at the microscopic level, temperature-dependent circular dichroism (CD) measurements revealed that the left-handed (<I>M</I>-type) helicity of supramolecular polymers TPA-1 and TPA-2 was inverted to the right-handed (<I>P</I>-type) helicity during heating. The (+/−) pattern of the vibrational circular dichroism (VCD) signal in the region of amide groups of self-assembled TPA-1 was also converted to the (−/+) pattern of the VCD signal. This indicates that the conformation of achiral gycine groups with the left-handed orientation was changed to the conformation of the glycine groups with the right-handed orientation. However, at the macroscopic level, the left- and the right-handed helical fibers were observed to coexist in self-assembled TPA-1 and TPA-2 at lower and higher temperatures. In contrast, no helicity conversion with the increase in temperature was observed for self-assembled TPA-3, which exhibited an ambiguous left-handed helical structure with a long helical pitch. Furthermore, the origin of the helical inversion at the microscopic level was supported <I>via</I> computational simulations. The helical inversion was possibly due to a molecular conformational change of flexible glycine moieties during the formation of supramolecular polymers. Based on AFM observations and DFT calculations, we conclude that even though either the positive or the negative signal of supramolecular polymers TPAs was obtained in CD spectra, the right- and the left-handed supramolecular polymer TPAs co-existed at the microscopic and macroscopic levels. Thus, the handedness of supramolecular polymers TPAs was determined by relative distribution of the right- and left-handed helical fibers.</P>

폐불가사리를 이용한 인산칼슘 제제의 제조

고철호,송현수,윤존도,곽재표 경남대학교 신소재연구소 2002 신소재연구 Vol.14 No.-

폐불가사리를 이용하여 고순도의 산화칼슘, 인산일수소 칼슘(DCPD, DCPA)과 파이로인산 칼슘(CPP) 등의 칼슘제제를 제조하였으며, 제조된 인산일수소 칼슘(DCPA)은 순도가 96.8%, 입도가 5.5㎛, 비표면적이 10.3㎡/g이었으며, 94%의 백색도를 가지는 양질의 분말인 것으로 평가되었다. 또한 DCPA를 하소하여 제조한 파이로인산 칼슘(CPP, Ca_2P_2O_7)의 순도는 97.9%, 입도가 4.4㎛, 비표면적인 1.5㎡/g이었으며, 백색도는 98%, pH는 7.0±0.2이었다. Calcium Oxide(CaO), Dicalcium Phosphates Dihydrate(DCPD), Dicalcium Phosphates Anhydrate(DCPA) and Calcium Pyrophosphates(CPP) of High purity were prepared from starfish by heat treatment and chemical reaction. It was characterized that Dicalcium Phosphates Anhydrate(DCPA) was the purity of 96.8%, the particle sized of 5.5㎛, specific surface area of 10.3㎡/g and standard of white color of 94%. It was characterized that Calcium Pyrophosphates(CPP) prepared from Dicalcium Phosphates Anhydrate(DCPA) was the purity of 97.9%, the particle size of 4.4㎛, the specific surface area of 1.5㎡/g, standard of white color of 98% and 7.0±0.2pH.

Morin, a Flavonoid from Moraceae, Induces Apoptosis by Induction of BAD Protein in Human Leukemic Cells

Park, Cheol,Lee, Won Sup,Go, Se-Il,Nagappan, Arulkumar,Han, Min Ho,Hong, Su Hyun,Kim, Gon Sup,Kim, Gi Young,Kwon, Taeg Kyu,Ryu, Chung Ho,Shin, Sung Chul,Choi, Yung Hyun MDPI 2015 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.16 No.1

<P>Evidence suggests that phytochemicals can safely modulate cancer cell biology and induce apoptosis. Here, we investigated the anti-cancer activity of morin, a flavone originally isolated from members of the Moraceae family in human leukemic cells, focusing on apoptosis. An anti-cancer effect of morin was screened with several human leukemic cell lines. U937 cells were most sensitive to morin, where it induced caspase-dependent apoptosis in a dose-dependent manner. It also induced loss of MMP (<I>ΔΨ<SUB>m</SUB></I>) along with cytochrome c release, down-regulated Bcl-2 protein, and up-regulated BAX proteins. The apoptotic activity of morin was significantly attenuated by Bcl-2 augmentation. In conclusion, morin induced caspase-dependent apoptosis through an intrinsic pathway by upregulating BAD proteins. In addition, Bcl-2 protein expression is also important in morin-induced apoptosis of U937 cells. This study provides evidence that morin might have anticancer properties in human leukemic cells.</P>

THE CHANNEL HOLDING TIME DISTRIBUTION IN A CELLULAR TELEPHONE SYSTEM WITH SOFT HANDOFF

Moo Ho Cho,Kwang Sik Kim,Go Whan Jin,Cheol Hye Cho,Kyoung Rok Cho 대한전자공학회 1996 대한전자공학회 워크샵 Vol.1996 No.-