Feasibility Study of Polymer Gel Dosimetry Using a 3D Printed Phantom for Liver Cancer Radiotherapy

Minsik Lee,Seonyeong Noh,KyoungJun Yoon,Sang-Wook Lee,Sang Min Yoon,Jinhong Jung,Chiyoung Jeong,Jungwon Kwak 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.76 No.6

In this study, a new three-dimensional (3D) volumetric dosimetry method utilizing gel dosimetry with a patient-specific (PS) 3D-printed phantom was developed. A PS 3D-printed phantom that closely mimics the actual tumor and surrounding tissues was demonstrated using a 3D printer (3Dison Plus, Lokit, Korea). MAGAT normoxic polymer gel was filled in the tumor-shaped cavity of the 3D-printed phantom to represent the real tumor. Seven identical gel samples for dosimetric calibration were irradiated at different doses and scanned using magnetic resonance imaging. A chlorinated polyethylene filament was utilized as the 3D printing material. The two-dimensional gamma passing rates using the film were 96.1% and 84.3% for the 3%/3 mm and the 2%/1 mm dose accuracy/distance-to agreement criteria, respectively. The radiation dose-R2 (relaxation rate) calibration, with a coefficient of determination (R2) of 0.997, was applied for the absolute dose calibration. The overall gross tumor volume shape and the dose distribution of the gel measurement agreed reasonably well with the plan results. The 3D gamma passing rate was 91.2% for the 3%/3 mm criteria and decreased to 82.3% for the 2%/1 mm criterion. Our results suggest that polymer gel dosimetry with the 3D-printed phantom allows direct validation of the 3D dose distribution.

Relation between the emoticons and emotions

Minseop Kim,Juyong Chun,Seonyeong Jeon,Younha Chang,Pf. Youngshin Kwak 한국HCI학회 2017 한국HCI학회 학술대회 Vol.2017 No.2

This study aims to investigate relations between the emoticons and emotions using the ‘kakaotalk’ default emoticons. The emoticon distribution map would be made with new axes from PCA and some ‘Kakaotalk’ default emoticons. Facial expression and gesture cannot be expressed on mobile messenger. This leads to the global use of emoticon which complements the limitation of mobile messenger communication. Therefore, this study will see what emotions are delivered by each emoticons. 8 adjectives are generated and reduced through focus group interview, categorizing, and literature studies to evaluate stimuli, which is emoticons consisted of facial expression and motion. 37 emoticons are selected as the stimuli based on our own criteria such as emoticons that express emotions with a various degree rather than situations. The semantic differential experiment is performed with 12 subjects and monopolar scales of 8 adjectives. After PCA, the 1<SUP>st</SUP> principal component is defined as positiveness and 2<SUP>nd</SUP> one is unpredictability, which explains the results up to about 80%. Some emotions were orthogonal to one another and there are more various emotions in negative emoticons rather than positive space. We concluded that the threshold for using positive emoticons is much higher in comparison with that of negative emoticon. There were somewhat empty space at the positive area in the emoticon distribution map, which means less expressed emotion space through emoticons at the positive area. The emoticon designer could focus on that empty space on the map to fascinate messenger’s users.

Oxidative biodegradation of 4-chlorophenol by using recombinant monooxygenase cloned and overexpressed from <i>Arthrobacter chlorophenolicus</i> A6

Kang, Christina,Yang, Jun Won,Cho, Wooyoun,Kwak, Seonyeong,Park, Sungyoon,Lim, Yejee,Choe, Jae Wan,Kim, Han S. Elsevier 2017 Bioresource technology Vol.240 No.-

<P><B>Abstract</B></P> <P>In this study, <I>cphC-I</I> and <I>cphB,</I> encoding a putative two-component flavin-diffusible monooxygenase (TC-FDM) complex, were cloned from <I>Arthrobacter chlorophenolicus</I> A6. The corresponding enzymes were overexpressed to assess the feasibility of their utilization for the oxidative decomposition of 4-chlorophenol (4-CP). Soluble CphC-I was produced at a high level (∼50%), and subsequently purified. Since CphB was expressed in an insoluble form, a flavin reductase, Fre, cloned from <I>Escherichia coli</I> was used as an alternative reductase. CphC-I utilized cofactor FADH<SUB>2</SUB>, which was reduced by Fre for the hydroxylation of 4-CP. This recombinant enzyme complex exhibited a higher specific activity for the oxidation of 4-CP (45.34U/mg-protein) than that exhibited by CphC-I contained in cells (0.18U/mg-protein). The Michaelis-Menten kinetic parameters were determined as: <I>v<SUB>max</SUB> </I> =223.3μM·min<SUP>−1</SUP>, <I>K<SUB>M</SUB> </I> =249.4μM, and <I>k<SUB>cat</SUB>/K<SUB>M</SUB> </I> =0.052min<SUP>−1</SUP>·μM<SUP>−1</SUP>. These results could be useful for the development of a new biochemical remediation technique based on enzymatic agents catalyzing the degradation of phenolic contaminants.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>Arthrobacter chlorophenolicus</I> A6 possesses DNA genes for 4-chlorophenol degradation. </LI> <LI> Soluble form CphC-I was expressed, whereas CphB expressed in an insoluble form. </LI> <LI> CphC-I exhibited high specific activity when coupled with a flavin reductase, Fre. </LI> <LI> <I>v</I> <SUB>max</SUB> =223.3μM·min<SUP>−1</SUP>, <I>K<SUB>M</SUB> </I> =249.4μM, and <I>k<SUB>cat</SUB>/K<SUB>M</SUB> </I> =0.052min<SUP>−1</SUP>·μM<SUP>−1</SUP>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Color change from yellow to orange-red after 4-CP degradation by CphC-I. CphC-I concentration from 0.1 to 25μM from left to right.</P> <P>[DISPLAY OMISSION]</P>

Identification of the upstream 4-chlorophenol biodegradation pathway using a recombinant monooxygenase from <i>Arthrobacter chlorophenolicus</i> A6

Cho, Su Yeon,Kwean, Oh Sung,Yang, Jun Won,Cho, Wooyoun,Kwak, Seonyeong,Park, Sungyoon,Lim, Yejee,Kim, Han S. Elsevier 2017 Bioresource technology Vol.245 No.2

<P><B>Abstract</B></P> <P>This study aimed to clarify the initial 4-chlorophenol (4-CP) biodegradation pathway promoted by a two-component flavin-diffusible monooxygenase (TC-FDM) consisting of CphC-I and CphB contained in <I>Arthrobacter chlorophenolicus</I> A6 and the decomposition function of CphC-I. The TC-FDM genes were cloned from <I>A. chlorophenolicus</I> A6, and the corresponding enzymes were overexpressed. Since CphB was expressed in an insoluble form, Fre, a flavin reductase obtained from <I>Escherichia coli</I>, was used. These enzymes were purified using Ni<SUP>2+</SUP>-NTA resin. It was confirmed that TC-FDM catalyzes the oxidation of 4-CP and the sequential conversion of 4-CP to benzoquinone (BQN)→hydroquinone (HQN)→HQL. This indicated that CphC-I exhibits substrate specificity for 4-CP, BQN, and HQN. The activity of CphC-I for 4-CP was 63.22U/mg-protein, and the Michaelis-Menten kinetic parameters were <I>v<SUB>max</SUB> </I> =0.21mM/min, <I>K<SUB>M</SUB> </I> =0.19mM, and <I>k<SUB>cat</SUB> </I>/<I>K<SUB>M</SUB> </I> =0.04mM<SUP>−1</SUP> min<SUP>−1</SUP>. These results would be useful for the development of a novel biochemical treatment technology for 4-CP and phenolic hydrocarbons.</P> <P><B>Highlights</B></P> <P> <UL> <LI> TC-FDM catalyzes initial 4-chlorophenol biodegradation pathway. </LI> <LI> 4-CP is converted sequentially to BQN→HQN→HQL by CphC-I. </LI> <LI> The activity of CphC-I for 4-CP was 63.22U/mg-protein. </LI> <LI> <I>v<SUB>max</SUB> </I> =0.21mM/min, <I>K<SUB>M</SUB> </I> =0.19mM, and <I>k<SUB>cat</SUB> </I>/<I>K<SUB>M</SUB> </I> =0.04mM<SUP>−1</SUP> min<SUP>−1</SUP>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Immobilization of enzymes onto clay minerals for the biochemical decomposition of 4-chlorophenol

( Oh Oh Sung Kwean ),( Su Yeon Cho ),( Jun Won Yang ),( Wooyoun Cho ),( Seonyeong Kwak ),( Sungyoon Park ),( Yejee Lim ),( Han S. Kima ) 한국물환경학회 2017 한국물환경학회·대한상하수도학회 공동 춘계학술발표회 Vol.2017 No.-

In this study an oxidative enzyme was immobilized onto inorganic backbone materials to stimulate the detoxification of toxic aromatic hydrocarbon compounds. Smectite clay minerals and soil organic matter were screened as an enzyme support and a binding agent, respectively. Montmorillonite of which inner pores are layered with nano-scale spacing planar was activated by humic acid. A dioxygenase obtained by cloning of its corresponding gene from Arthrobacter chlorophenolicus A6 was immobilized onto the humic acid-activated montmorillonite. Oxygenated metabolites such as catechol and 4-chlorocatechol were selected as target aromatic contaminants (primary substrates of enzyme). The enzyme immobilization yield was as high as 63% and the reductions in enzyme activity for the decomposition of substrate compounds during enzyme immobilization were minimal: 15% for catechol and 24% for 4-chlorocatechol, respectively. The kinetic analysis of the free and immobilized enzymes demonstrated a slight decrease of vmax and a marginal increase of KM as compared with those for the free enzyme, indicating the changes in enzyme activity perhaps due to the changes in enzyme conformation associated with its immobilization were minimal. The results for the effects of environmental factors including pH, temperature, and ionic strength on the activity of free and immobilized enzymes showed that the activity of free enzyme changed significantly in response to the changes of the environmental factors whereas that of immobilized enzyme was pretty much consistent. This indicated that the stability of enzyme against the abrupt changes in environmental factors can be greatly improved by enzyme immobilization. The results of this study support the feasibility of a new environmental fusion technology based on bio-technology and nano-technology for the development of biochemical treatment processes.