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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Chemical Society
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Journal DOI :
Korean Chemical Society
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Volume & Issues
Volume 58, Issue 6 - Dec 2014
Volume 58, Issue 5 - Oct 2014
Volume 58, Issue 4 - Aug 2014
Volume 58, Issue 3 - Jun 2014
Volume 58, Issue 2 - Apr 2014
Volume 58, Issue 1 - Feb 2014
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Conductance of a Single Molecule Junction Formed with Ni, Au, and Ag Electrodes
Kim, Taekyeong ;
Journal of the Korean Chemical Society, volume 58, issue 6, 2014, Pages 513~516
DOI : 10.5012/jkcs.2014.58.6.513
We measure the conductance of a 4,4'-diaminobiphenyl formed with Ni electrodes using a scanning tunneling microscope-based break-junction technique. For comparison, we use Au or Ag electrodes to form a metal-molecular junction. For molecules that conduct through the highest occupied molecular orbital, junctions formed with Ni show similar conductance as Au and are more conductive than those formed with Ag, consistent with the higher work function for Ni or Au. Furthermore, we observe that the measured molecular junction length that is formed with the Ni or Au electrodes was shorter than that formed with the Ag electrodes. These observations are attributed to a larger gap distance of the Ni or Au electrodes compared to that of the Ag electrodes after the metal contact ruptures. Since our work allows us to measure the conductance of a molecule formed with various electrodes, it should be relevant to molecular electronics with versatile materials.
Effects of NaCl and n-Butanol on the Solubilization of 4-Halogenated Phenols in Aqueous Solution of TTAB
Lee, Byung-Hwan ;
Journal of the Korean Chemical Society, volume 58, issue 6, 2014, Pages 517~523
DOI : 10.5012/jkcs.2014.58.6.517
The micellization of TTAB(tetradecyltrimethylammonium bromide) and the solubilization of 4-halogenated phenol isomers in aqueous solution of that surfactant in water have been studied by the UV-Vis spectrophotometric method. Those properties in aqueous solutions of NaCl and n-butanol have been also measured to determine the interactions between the micelle and 4-halogenated phenols and the solubilized sites of those molecules in the micelle. The results show that the values of
are all negative and the trends of those values depend on both the kinds and the concentrations of additives. Namely, by adding NaCl both
values are all decreasing, but by adding n-butanol the
value decreases and the
Large-Scale Assembly of Aligned Graphene Nanoribbons with Sub 30-nm Width
Kim, Taekyeong ;
Journal of the Korean Chemical Society, volume 58, issue 6, 2014, Pages 524~527
DOI : 10.5012/jkcs.2014.58.6.524
We report a simple yet efficient method to assemble large-scale aligned graphene nanoribbons (GNRs) with a width as small as 30 nm. The
nanowires (NWs) were aligned on a graphene surface via spraying a solution of the
NWs, and the graphene was selectively etched by the reactive ion etching method using the
NWs as a shadow mask. This process allowed us to prepare large scale patterns of the aligned GNRs on a
substrate. The orientation of the aligned and randomly oriented GNRs was compared by the atomic force microscope (AFM) images. We achieved the highly aligned GNRs along the flow direction of the
NWs solution. Furthermore, we successfully fabricated a field effect-transistor with the aligned GNRs and measured its electrical properties. Since our method enable to prepare the aligned GNRs over a large area, it should open up new way for the various applications.
Partial Miscibility of Binary Solution with Specific Interaction of Binomial Distribution
Jung, Hae-Young ;
Journal of the Korean Chemical Society, volume 58, issue 6, 2014, Pages 528~534
DOI : 10.5012/jkcs.2014.58.6.528
In some binary solution, closed miscibility loop of temperature-composition phase diagram occurs where both an upper critical solution temperature and a lower critical solution temperature exist. It is known that this phenomena occurs if specific interaction between molecules exists. There are several ways describing the specific interaction. In this work it is assumed that the total number of specific interactions is distributed according to binomial distribution. In this case, exact mathematical conditions for closed miscibility loop phase behavior are derived when the specific interaction is applied to regular solution theory, quasichemical theory and Flory-Huggins lattice theory. And we investigated the effect of parameters on the phase diagram. The phase diagram of water-nicotine is calculated and compared with experimental data.
Simultaneous Determination of Tetracycline Antibiotics by 3-Phase Hollow Fiber-Liquid Phase Microextraction (HF-LPME) and HPLC-UV/Vis
Oh, Woong Kyo ; Myung, Seung-Woon ;
Journal of the Korean Chemical Society, volume 58, issue 6, 2014, Pages 535~542
DOI : 10.5012/jkcs.2014.58.6.535
A simple and efficient preconcentration method was developed using three-phase liquid phase microextraction prior to HPLC-UV for simultaneous extraction and determination of tetracycline antibiotics (tetracycline, oxytetracycline, and chlortetracycline). The tetracycline antibiotics were separated simultaneously on a column (
) with high selectivity and sensitivity using gradient elution. Under optimized conditions (extraction solvent, heptanal; pH of donor, 9.0; pH of acceptor, 1.0; stirring speed, 700 rpm; NaCl salt, 0%; and extraction time, 60 min), enrichment factors (EF) were between 5.6 and 22.3. The limit of detection (LOD) and limit of quantitation (LOQ) in the spiked urine matrix were in the concentration range of
, respectively. The calibration curves were linear within the range of
with the square of the correlation coefficient being more than 0.995. The precision (as a relative standard deviation, RSD) and accuracy (as a relative recovery) within working range were 1.3~9.1% and 84~118%, respectively.
Quantitative Structure Activity Relationship Prediction of Oral Bioavailabilities Using Support Vector Machine
Fatemi, Mohammad Hossein ; Fadaei, Fatemeh ;
Journal of the Korean Chemical Society, volume 58, issue 6, 2014, Pages 543~552
DOI : 10.5012/jkcs.2014.58.6.543
A quantitative structure activity relationship (QSAR) study is performed for modeling and prediction of oral bioavailabilities of 216 diverse set of drugs. After calculation and screening of molecular descriptors, linear and nonlinear models were developed by using multiple linear regression (MLR), artificial neural network (ANN), support vector machine (SVM) and random forest (RF) techniques. Comparison between statistical parameters of these models indicates the suitability of SVM over other models. The root mean square errors of SVM model were 5.933 and 4.934 for training and test sets, respectively. Robustness and reliability of the developed SVM model was evaluated by performing of leave many out cross validation test, which produces the statistic of
and SPRESS = 7.902. Moreover, the chemical applicability domains of model were determined via leverage approach. The results of this study revealed the applicability of QSAR approach by using SVM in prediction of oral bioavailability of drugs.
β-Secretase (BACE1) Purification by Refolding Method and Complex with Hispidin
Lim, Ji-Hong ; Lee, Bo Ram ; Park, Hee Won ; Hong, Bum Soo ; Lim, Beong Ou ; Kim, Young Jun ;
Journal of the Korean Chemical Society, volume 58, issue 6, 2014, Pages 553~559
DOI : 10.5012/jkcs.2014.58.6.553
Alzheimer's disease (AD) is a devastating neurodegenerative disease that represents the most common form of dementia among the elderly population. The deposition of aggregated
) senile plaques in the human brain is a classic observation in the neuropathology of AD, yet an understanding of the mechanism of their formation remains elusive.
is formed through endoproteolysis of the amyloid precursor protein (APP) by
-site APP-cleaving enzyme) and
-secretase. In this study, BACE1 protein was successfully over-expressed, purified, and refolded and utilized in a binding study with hispidin. We developed a simpler refolding method using a urea gradient and size-exclusion gel filtration to purify an active BACE1 protein variant, in larger quantities than that reported previously, and measured the binding affinity of hispidin to the BACE1 protein variant through isothermal titration calorimetry.
Contribution of Electrostatic Interactions to Protein Folding Reaction
Kim, Dae Won ; Park, Soon-Ho ;
Journal of the Korean Chemical Society, volume 58, issue 6, 2014, Pages 560~568
DOI : 10.5012/jkcs.2014.58.6.560
The contribution of electrostatic interactions to protein folding reaction was studied by using mutant ubiquitin with lysine to alanine mutation at residue position 29. Based on the three dimensional structure of ubiquitin, lysine 29 is located close to negatively charged glutamate 16 and aspartate 21 and considered to stabilize the native state of ubiquitin by electrostatic interactions between these residues. The equilibrium unfolding experiment showed that the native stability was decreased by about ~20% upon mutation. This observation indicates lysine 29 indeed forms electrostatic interactions with nearby residues. Folding kinetics measurements using stopped-flow device and quantitative analysis of kinetics data indicate that ubiquitin folds from unfolded state to native state via intermediate state as observed previously. This intermediate state was observed to form immediately after the initiation of folding reaction. The folding intermediate was shown to be destabilized considerably upon lysine to alanine mutation. These observations indicate that electrostatic interactions can form early stage of protein folding and hence lead the folding reaction.
A Versatile Synthesis of O-Desmethylangolensin Analogues from Methoxy-Substituted Benzoic Acids
Hong, Hyo Jeong ; Lee, Jae In ;
Journal of the Korean Chemical Society, volume 58, issue 6, 2014, Pages 569~574
DOI : 10.5012/jkcs.2014.58.6.569
The synthesis of O-desmethylangolensin (O-DMA) analogues from methoxy-substituted benzoic acids was described. Treatment of methoxy-substituted benzoic acids with 2 equiv of ethyllithium afforded methoxypropiophenones, which were subsequently transformed to ethyl 2-(methoxyphenyl)propionates via 1,2-rearrangement of the methoxyphenyl group using
in triethyl orthoformate. After hydrolysis with KOH, the 2-(methoxyphenyl)propionic acids were reacted with di-2-pyridyl carbonate to afford 2-pyridyl 2-(methoxyphenyl)propionates, which were acylated with methoxy-substituted phenylmagnesium bromides to give methoxy-
-methyldesoxybenzoins. The methoxy groups of these compounds were selectively or fully demethylated using boron tribromide to give diverse O-DMA analogues in high yields.
Drug Release from Thermosensitive Liposomes by High-Intensity Focused Ultrasound
Jeon, Ye Won ; Cho, Sun Hang ; Han, Hee Dong ; Shin, Byung Cheol ;
Journal of the Korean Chemical Society, volume 58, issue 6, 2014, Pages 575~579
DOI : 10.5012/jkcs.2014.58.6.575
Development of liposomes has been actively studied for effective delivery of drug at tumor site. However, despite their preferential accumulation at tumor site, the therapeutic efficacy of such liposomal drug has been limited because of low drug release. Therefore, we developed a temperature-sensitive liposome (TSL), which can be made to maximize release of drug by external stimulation such as ultrasound. Doxorubicin (DOX) as a model drug was encapsulated into TSL by a pH gradient method. The particle size of the TSL was
. Surface charge was
. Release of drug from TSLs was up to 80% within 15 min at over
measured by fluorescence intensity. Cytotoxicity of released DOX from TSLs with ultrasound was highly increased compared to TSLs without ultrasound. Taken together, we demonstrate that temperature sensitive drug release from TSLs with ultrasound, which may be useful for cancer therapy to increase drug concentration at tumor site by external stimulation.
Analysis of Coherence in Middle School Students' Representation of Particulate Concepts
Yoon, Heojeong ; Lee, Yoonha ;
Journal of the Korean Chemical Society, volume 58, issue 6, 2014, Pages 580~589
DOI : 10.5012/jkcs.2014.58.6.580
The concepts used to explain specific phenomenon can be influenced by context or coherent regardless of context. The purpose of this study is to understand middle school students' concept of particles in particular context and to investigate the effects of context on concept of particles. A conceptual questionnaire was developed to find out how students represented particles in two contexts: solid and solution states of electrolytes, and ion precipitation reaction. The questionnaire was administered to
grade students after classes of 'electrolyte and ions' unit. The responses of students were analyzed using framework developed for categorization of students' concepts. The results are as follows: First, it was found that students used various concepts on particles when they explained solid and solution state of electrolytes, respectively. Second, we identified students' concepts of particles used to explain ion precipitation reaction. In addition, we recognized that majority of students failed to write correct chemical symbols. Third, approximately 79% of students showed coherent responses for explanation of particles in solution state of both electrolytes and ion precipitation reaction. About 57% of students had scientific concepts. Some suggestions were made based on results for acquisition of scientific concepts on particles in different contexts.
The Perception of Middle School Teachers about the Environmental Problem
Park, Jaemoon ; Lee, Sujin ; Moon, Seongbae ;
Journal of the Korean Chemical Society, volume 58, issue 6, 2014, Pages 590~599
DOI : 10.5012/jkcs.2014.58.6.590
Environmental education, effectively performed at school, is very important to solve the environmental problems. Moreover the survey for teacher's perception is essential. The purpose of the study was to investigate the perception of environmental problems of middle school teachers in Pusan. The survey was done twice in 2007 and 2012, and based on the time intervals, careers, and major of the teachers. 200 teachers were chosen in 2007 and 300 teachers in 2012. How many environmental problems occurred during this time period affected the 471 teachers' perception was investigated and analyzed. The results are as follows. First, the perception difference of environmental problems was meaningful between two time intervals (p<.01). Especially, the perception of modern environmental problems and carbon emission showed considerable increase in both science and non-science major teachers. This may be caused by the climate change and the severity of lifestyles of indiscriminate consumerism. Second, the perception difference of environmental problems by careers was also meaningful (p<.01). Overall, the perception was obvious on the aspects of modern environmental problems, carbon emission, destruction of ozone layers, nuclear wastes, environmental hormones, and red tides. Teachers, having more careers irrespective of their teaching subjects, showed higher perception on the seriousness of environmental pollution, the necessity of environmental conservation, and the importance of health. Third, the perception of environmental problems between science and non-science major teachers was meaningful (p<.01). Particularly, the perception in the broad environmental problems was distinctive between them.
An Comparison Analysis of Science Writing Tasks in the Chemistry Domain of Middle School Science Textbooks Developed under the 2007 & the 2009 Revised National Curriculums (RNC)
Lee, Gyu Hui ; Hong, Hun-Gi ;
Journal of the Korean Chemical Society, volume 58, issue 6, 2014, Pages 600~611
DOI : 10.5012/jkcs.2014.58.6.600
In this study, we sampled science writing tasks and investigated their frequency of use shown in the chemistry domain from two sets of 18 middle school science textbooks developed under the 2007 Revised National Curriculum(RNC) and the 2009 RNC, respectively. In addition, we categorized the sampled science writing tasks depending on the cognitive process and type of writing and compared with the results obtained from analysis of global issues presented in the science writings. From the textbooks developed under the 2007 RNC, a total of 183 science writing tasks were identified in which 10.17 tasks per textbook and 1.32 tasks per 10 pages were used averagely. A total of 168 were identified from the textbooks for the 2009 RNC. Among them, 9.33 tasks per textbook and 1.23 tasks per 10 pages were used on average. Comparing with these results, the average frequency of use of the tasks per textbook and per ten pages were decreased, respectively. Moreover, the number of science writing tasks were found in each curriculum varied considerably depending on the units and the publishers, and that the writing tasks were mainly arranged in the finale, wrapping up stage. In the analysis of science writing tasks according to the cognitive process, the highest and lowest frequency of use were observed in the category of 'understand' and 'remember', respectively. According to the classification of science writing tasks based on the types of writing, the writings for the information delivery were most used and the highest frequency of use was observed in the category of 'understand' of the cognitive process belonging to 'information delivery'. As for the results of the analysis of global issues, the number of science writing tasks including global issues increased from 21(11.48%) in the 2007 RNC to 33(19.64%) in the 2009 RNC. Furthermore, science writing tasks associated with protection of environment showed the highest frequency of use in the both curriculums, and it was analyzed that the materials of global issues used in the 2009 RNC were much more diverse.
The Effect of Peer Mentoring Activity on Academic Achievement and Views on Nature of Science
Song, Bon-Uk ; Moon, Seongbae ;
Journal of the Korean Chemical Society, volume 58, issue 6, 2014, Pages 612~621
DOI : 10.5012/jkcs.2014.58.6.612
The purpose of this study is to examine the effect of peer mentor on academic achievement of mentee and views on nature of science. The experimental group was consisted of 20 mentor students, formed as a high level being less than 20% of achievement test, and 20 mentee, low level less than 15% of that. The mentoring activities were conducted 23 times for 8 weeks and progressed for 15~30 minutes after the teacher's main classes. During the mentoring activity, studying materials were provided to students and mentees asked to mentors for the parts which were difficult to understand among the contents of classes and got replies by arranging studying materials. As the results of this study, First, peer mentoring activity was shown statistically meaningful effects and improved the academic achievement in mentee's group than traditional classes (p<.01). But, there was no meaningful effects on mentor's achievement (p>.05). Second, the students who took part in the peer mentoring activity said that it was a good chance to have a close relationship between mentors and mentees. Also, the science recognition of the students were changed positively even though the science is hard and difficult to memorize, but interesting subject included the experiments. Third, the satisfaction of the peer mentoring activity is high both mentors and mentees (p<.01). Fourth, according to mentees' positive attitude, and as the level of closeness is higher, the academic achievement was increased. Based on this study, if teachers organize mentoring team effectively according to their closeness, one can expect the positive change of recognition on science as well as academic achievement of mentees.
Analyzing the Trend and Creativity of Entry in Chemistry Sector of National Science Exhibition
Ryu, Sigyeong ; Park, Jongseok ;
Journal of the Korean Chemical Society, volume 58, issue 6, 2014, Pages 622~629
DOI : 10.5012/jkcs.2014.58.6.622
This study analyze the trend and creativity of entry in chemistry sector of National Science Exhibition. For this study, award-winning entry in chemistry sector of National Science Exhibition during the last five years (2009-2013) were analyzed. The inquiry subject were classified six different items. The creativity evaluation rating of each entry was decided by a survey of the evaluator groups; teachers who participated in the training, winners' teacher. The results turned out as follows: First, In case of trying to choose inquiry subject of entry, it would be better for teacher to guide student into choosing everyday life or natural phenomenon in elementary school level, everyday life or academic area in middle school level, academic area in high school. Second, there was no correlation of creativity rating and actual award rating. Therefore, teacher will need to guide students' research synthetically in a variety of research areas.
Current Situation of Implementing Cooperative Learning in Elementary Science Classes and Teachers' Perceptions toward Cooperative Learning
Noh, Taehee ; Han, Jiwon ; Kang, Sukjin ;
Journal of the Korean Chemical Society, volume 58, issue 6, 2014, Pages 630~637
DOI : 10.5012/jkcs.2014.58.6.630
In this study, we investigated the current situation of implementing cooperative learning (CL) in elementary science classes and teachers' perceptions toward CL in science instructions. Participants were 138 elementary school teachers and 96 of them had experiences of implementing CL in their science classes. We developed a questionnaire on the basis of previous studies. The results indicated that many teachers did not seem to comprehend CL and some of them did not seem to distinguish CL from the traditional small group learning. The teachers who had experiences of implementing CL tended to exhibit positive perceptions toward CL than their counterpart in the effects of CL category whereas they did not show any positive evidence in the processes of CL category. The influences of teaching career and the experience of participating inservice training about CL on teachers' perceptions toward CL were not clear. Educational implications are discussed.
An Analysis on Mentor Teacher's Difficulties during Collaborative Mentoring Program
Choi, So Jung ; Kwon, Jeongin ; Nam, Jeonghee ;
Journal of the Korean Chemical Society, volume 58, issue 6, 2014, Pages 638~648
DOI : 10.5012/jkcs.2014.58.6.638
The purpose of this study was to examine mentor teachers' difficulties during their collaborative mentoring process to improve beginning science teachers' teaching practice. Participants were fourteen science teachers. This study collected questionnaires for mentor teachers' perception of the mentoring program, questionnaires for mentor teachers' efficacy, a record and transcript of interview, a record and transcript of mentoring conversation, and mentor teachers' journals for the study. The result showed that mentor teachers were having difficulties with mentee teachers when they have different major or work in different levels of school, and they found it hard to set aside time for mentoring due to heavy amount of school work. Also, they had low self-confidence experiencing a lack of expertise as a mentor teacher, and some mentor teachers were having difficulties in building a rapport with mentee teachers. Mentor teachers had difficulties as well when they have different point of view with mentee teachers about mentoring.
Study on Enhancement Problem Solving Ability through Science Writing Activities
Park, Hyejin ; Kang, Soonhee ;
Journal of the Korean Chemical Society, volume 58, issue 6, 2014, Pages 649~657
DOI : 10.5012/jkcs.2014.58.6.649
The purpose of this study was to develop a teaching strategy focused on science writing and to investigate its effects on enhancing students' problem solving ability. A teaching strategy using science writing enhancing problem solving ability (REWS model) was designed. The REWE model consisted of four stages: 1) Sensing and Stating of Scientific Problem by Reading (R stage), 2) Exploring Problem (E stage) 3) Explaining by Writing (W stage), 4) Integrated problem-solving (S stage). 135 10th grade of students were assigned to one experimental group and one control group. Students in the experiment group were taught by REWE model. Students in control group were taught by traditional lecture-based instructions. The program was implemented over a semester. The results indicated that the experimental group presented statistically meaningful improvement in critical thinking necessary to solve problems (p<.05). This study suggests that science writing can be effective for improvement of problem solving ability.
Pre-Service Science Teachers' Understanding and Views of Argument-Based Inquiry Approach
Choi, Aeran ;
Journal of the Korean Chemical Society, volume 58, issue 6, 2014, Pages 658~666
DOI : 10.5012/jkcs.2014.58.6.658
This study was designed to explore pre-service secondary science teachers' understanding and views of argument-based inquiry approach. Participants were 17 pre-service secondary science teachers enrolled in chemistry curricular materials and teaching methods course for majors in the college of education at a university in Seoul. Main data sources included each student responses to an open ended survey and individual interviews. Data analyses indicated that the pre-service teachers had very limited and biased understanding on scientific inquiry at the beginning of the semester. While the pre-service teachers understood that scientific inquiry should be an essential component of science teaching, a few pre-service teachers mentioned 'argumentation' or 'discussions' when they defined what scientific inquiry is. The majority of the pre-service teachers mentioned that science should be taught through scientific inquiry since science is inquiry itself. However, the pre-service teachers expressed several potential barriers and their concerns on implementing argumentation in scientific inquiry. While they concerned about students' lack of participation at the beginning of the semester, they concerned more about the teachers' ability of leading student argumentation at the end of the semester.
The Effect of Inquiry Teaching Strategy Enhancing the Logical Thinking Skill through the Science Teaching about the 1st Year Students of the Junior High School
Hong, Hyein ; Kang, Soonhee ;
Journal of the Korean Chemical Society, volume 58, issue 6, 2014, Pages 667~680
DOI : 10.5012/jkcs.2014.58.6.667
The purpose of this study was to develop teaching stratege focused on Conservational reasoning, Proportional reasoning, Variable-controlling reasoning, Probabilitic reasoning, Correlational reasoning, Combinational reasoning and investigate its effects on enhancing students' logical thinking skills through the science teaching on common education. And the teaching materials was implemented to 110 students in middle school over about six months. The results indicated that the experimental group presented statistically meaningful improvement in logical thinking skills (p<05). Especially, this teaching stratege was effective on Conservational reasoning, Variable-controlling reasoning, Combinational reasoning but was not effective on Proportional reasoning, Probabilitic reasoning, Correlational reasoning (p<.05). Logical thinking according to the teaching strategy skill was not affected by gender, cognitive level, academic achievement (p<.05).
Spectroscopic Properties and Ligand Field Analysis of trans-[Cr(Me
Choi, Jong-Ha ; Ryoo, Keon Sang ; Hong, Yong Pyo ;
Journal of the Korean Chemical Society, volume 58, issue 6, 2014, Pages 681~685
DOI : 10.5012/jkcs.2014.58.6.681
Chemical Constituents of the Halophyte Vitex rotundifolia
Kim, You Ah ; Kim, Hojun ; Oh, Kwang-Suk ; Seo, Youngwan ;
Journal of the Korean Chemical Society, volume 58, issue 6, 2014, Pages 686~690
DOI : 10.5012/jkcs.2014.58.6.686