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Ring-opening metathesis polymerization of tetracyclododecene using various catalyst systems
Kim, Jaehoon,Wu, Chun Ji,Kim, Wan-Joo,Kim, Junhyuk,Lee, Hyunjoo,Kim, Jae-Duck Wiley Subscription Services, Inc., A Wiley Company 2010 Journal of applied polymer science Vol.116 No.1
<P>Ring-opening metathesis polymerization (ROMP) of a polycyclic olefin monomer (tetracyclododecene, TCD) was carried out using various catalyst systems. The catalysts included titanium-based ternary system (titanium tetrachloride, TiCl<SUB>4</SUB>/triethylaluminum, Et<SUB>3</SUB>Al/triethylamine, Et<SUB>3</SUB>N), tungsten-based ternary system (tungsten hexachloride, WCl<SUB>6</SUB>/triisobutyl aluminum, (i-Bu)<SUB>3</SUB>Al/ethanol), and a ruthenium benzylidene catalyst (Grubbs 1st catalyst). The Grubbs 1st catalyst was most active in ROMP of TCD. The tungsten-based catalyst was found to be more active than the titanium-based catalyst. In contrast to the titanium-based and the Grubbs 1st catalysts, ROMP of TCD with the tungsten-based catalyst was very sensitive to gelation in the course of reaction. The effects of ethanol, WCl<SUB>6</SUB> concentration, TCD/WCl<SUB>6</SUB> ratio, and 1-hexane on the polymerization yield and the polymer gel formation were investigated in detail, and optimized ROMP conditions were determined. Chemical structure of synthesized polymer was characterized using one- and two-dimensional 150 MHz <SUP>13</SUP>C and 600 MHz <SUP>1</SUP>H nuclear magnetic resonance spectroscopy, molecular weights were measured using gel-permeation chromatography, and thermal properties were characterized using differential scanning calorimetry. Number-average molecular weights (M<SUB>n</SUB>) of the polymer were in the range of 1.5–4.7 × 10<SUP>4</SUP> g/mol, and glass transition temperatures were in the range of 185–220°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010</P>
Toward Modular Analysis of Supramolecular Protein Assemblies
Kim, Jaehoon,Kim, Jin-Gyun,Yun, Giseok,Lee, Phill-Seung,Kim, Do-Nyun American Chemical Society 2015 Journal of chemical theory and computation Vol.11 No.9
<P>Despite recent advances in molecular simulation technologies, analysis of high-molecular-weight structures is still challenging. Here, we propose an automated model reduction procedure aiming to enable modular analysis of these structures. It employs a component mode synthesis for the reduction of finite element protein models. Reduced models may consist of real biological subunits or artificial partitions whose dynamics is described using the degrees of freedom at the substructural interfaces and a small set of dominant vibrational modes only. Notably, the proper number of dominant modes is automatically determined using a novel estimator for eigenvalue errors without calculating the reference eigensolutions of the full model. The performance of the proposed approach is thoroughly investigated by analyzing 50 representative structures including a crystal structure of GroEL and an electron density map of a ribosome.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jctcce/2015/jctcce.2015.11.issue-9/acs.jctc.5b00329/production/images/medium/ct-2015-00329r_0015.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ct5b00329'>ACS Electronic Supporting Info</A></P>
Kim, Jun Young,Cho, Eunae,Kim, Jaehoon,Shin, Hyeonwoo,Roh, Jeongkyun,Thambidurai, Mariyappan,Kang, Chan-Mo,Song, Hyung-Jun,Kim, SeongMin,Kim, Hyeok,Lee, Changhee Optical Society of America 2015 Optics express Vol.23 No.19
<P>We demonstrate that nanocrystalline Al-doped zinc oxide (n-AZO) thin film used as an electron-extraction layer can significantly enhance the performance of inverted polymer solar cells based on the bulk heterojunction of poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl] (PCDTBT) and [6,6]-phenyl C<sub>71</sub>-butyric acid methyl ester (PC<sub>70</sub>BM). A synergistic study with both simulation and experiment on n-AZO was carried out to offer a rational guidance for the efficiency improvement. As a result, An n-AZO film with an average grain size of 13 to 22 nm was prepared by a sol-gel spin-coating method, and a minimum resistivity of 2.1 ?? 10<sup>-3</sup> 곽·cm was obtained for an Al-doping concentration of 5.83 at.%. When an n-AZO film with a 5.83 at.% Al concentration was inserted between the ITO electrode and the active layer (PCDTBT:PC<sub>70</sub>BM), the power conversion efficiency increased from 3.7 to 5.6%.</P>
일부 의료서비스업 VDT작업자의 상지 근골격계 증상의 정도와 관련된 요인
김형렬,원종욱,송재석,김현수,김치년,노재훈 大韓産業醫學會 2003 대한직업환경의학회지 Vol.15 No.2
목적: 본 연구는 상지 근골격계 질환의 유병율이 높은 집단으로 알려진 VDT작업자를 대상으로 이들의 근골격계 통증을 정량화하고, 정량화된 통증점수를 종속변수로 하여, 이와 관련성을 갖는 작업요인, 사회심리적 요인을 파악하고자 하였다. 방법: 서울지역에 위치한 1500병상 규모의 대학병원에 근무하고 단말기 작업을 주로 수행한다고 알려진 부서에 대해 병원내 안전관리과와 협의를 거쳐 163명을 연구대상으로 선정하였다. 이중 138명이 설문에 참가하였고, 이들을 최종 연구대상으로 하였다. 설문지를 가지고 연구변수를 측정하여, 나이, 근무연수, 가사노동의 정도 등의 인구학적 변수와 직무스트레스 및 사회적지지, 근골격계 증상, 통증의 양상 등을 조사하였다. 분석방법은 일반적 특성 및 작업특성, 통증의 양상을 성별에 따라 파악하였고, 통증점수의 타당성을 검정하기 위해, 통증점수의 구성요소와 통증점수를 시각적 상사척도와 상관성 검정을 시행하였다. 통증점수를 종속변수로 하고 직무요구도, 직무재량도, 동료의지지, 상사의지지, 여러작업환경특성, 인구학적 특징 등을 독립변수로 하여 다중회귀분석을 시행하였다. 결과: 첫째 통증의 정량화를 위해 사용한 통증평정지수는 시각적 상사척도와의 상관관계가 높은 것으로 나타나, 어느 정도의 타당성을 지닌 방법으로 해석할 수 있었다. 둘째, 이 통증 점수를 종속변수로 하여, 관련요인 분석한 다중회귀분석에서 직무요구도가 높을수록 통증의 정도가 높고(p<0.01), 여성일수록 남성에 비해 높은 통증점수를 보였다(p<0.01). 결론: 근골격계 질환의 높은 유병율을 보이는 집단의 경우, 이들의 증상 유무만을 가지고 관련요인을 분석하는 방법을 사용하기 어렵다. 따라서 이런 경우, 통증을 정량화하여, 다양한 관련요인을 찾으려는 노력이 필요하며, 본 연구에서 사용한 통증평정지수는 타당성을 지닌 정량화 방법이라고 여겨진다. 또한 본 연구에서는 직무요구도가 높을수록, 여성일수록 높은 통증점수를 보였다. Objectives: This study was designed to quantify symptoms in the upper extremities and to identify the pain related factors among hospital workers using video display terminals. Methods: The subject-group consisted of 138 employees working at a hospital using video display terminals. A structured questionnaire was used to estimate the participants' general characteristics, and job contents. Job stress was measured using Karaseks JCQ(Job Content Questionnaire). Pain in the upper extremities was identified according to the NIOSH symptoms survey criteria. Quantification was measured using Kim Chul's method. Pearson's Correlation analysis was used to identify validity in quantification. VAS(visual analog scale) was used to compare with this method. Multiple regression analyses elucidated the relationship between quantified pain and various work factors, such as job stress. Data were analysed with SAS 6.12 program. Results: First, in quantification using Kim Chul's method, the correlation between modified PRS(pain rating score) and VAS was extremely high by 0.60(P<0.01), indicating the high validity of PRS. Second, the groups of high job demand, high job control, and females were related to an increased pain level. Conclusions: These results suggest that the self pain assessment method, PRS, is valuable and useful in analyzing occupational musculoskeletal symptoms. High demand, job control and gender may influence the levels of pain. Prospective studies about musculoskeletal disorder are required.