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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 51, Issue 6 - Dec 2007
Volume 51, Issue 5 - Oct 2007
Volume 51, Issue 4 - Aug 2007
Volume 51, Issue 3 - Jun 2007
Volume 51, Issue 2 - Apr 2007
Volume 51, Issue 1 - Feb 2007
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DFT Studies on the Proton Affinities of Oxazole
Lee, Hyun-Mee ; Lee, Gab-Yong ;
Journal of the Korean Chemical Society, volume 51, issue 1, 2007, Pages 7~13
DOI : 10.5012/jkcs.2007.51.1.007
The oxazole plays an important role in the binding of lexitropsin to the guanine-cytosine base pair from minor groove of DNA. The geometry optimization is performed with DFT calculations for the two possible conformations of the protonated oxazole. The proton affinities are calculated at B3LYP level of theory with 6-31G* basis set for the optimized geometry. It is found that the proton affinites of the conformations in which the oxazole nitrogen is the protonation center are greater than that of the conformations in which the oxazole oxygen is the protonation center. This result is in good agreement with molecular electrostatic potential (MEP) contour map. The proton affinities are also studied for various substituted oxazoles with the electron-donating and -withdrawing groups to estimate substitutent effect on the proton affinity at the hydrogen bonding site of the oxazoles. it is shown that the electron-donating substituents increase the proton affinity of oxazole, while the electron-withdrawing substituents decrease it.
Anodic Dissolution of Electrodeposited Iron Group Elements in Phthalate Buffer Solution
Chon, Jung-Kyoon ; Kim, Youn-Kyoo ;
Journal of the Korean Chemical Society, volume 51, issue 1, 2007, Pages 14~20
DOI : 10.5012/jkcs.2007.51.1.014
The anodic dissolution of electrodeposited iron group elements (Fe, Co, Ni) were studied in phthalate buffer solution. The pH dependence of the corrosion potential, the corrosion current and Tafel slope was measured for each element. Based on the electrochemical parameters including Tafel slopes, we proposed the redox mechanism of the corrosion and the passivation. The adsorption of various phthalate species on the electrodeposited iron group elements seemed to be affected the corrosion mechanisms.
Effect of Ethanol on the Protolytic Properties of the Vitamins B Group
Ghasemi, J. ; Shiri, F. ;
Journal of the Korean Chemical Society, volume 51, issue 1, 2007, Pages 21~30
DOI : 10.5012/jkcs.2007.51.1.021
A multiwavelength spectrophotometric titration method was applied to study protolytic constants of four water-soluble vitamins, folic acid(vitamin B9 or B0), thiamine(vitamin B1), riboflavin(vitamin B2) and pyridoxal (vitamin B6) in binary ethanol-water mixtures at 25oC and an ionic strength of 0.1M NaNO3. The protolytic equilibrium constants, spectral profiles, concentration diagrams and also the number of components has been calculated from the curve fitting of the pH-absorbance data with appropriate mass balance equations by an established factor analysis model. DATAN program was used for determination of acidity constant and SPECFIT program was used for calculation of standard deviations and partial correlation coefficients. A glass electrode calibration procedure based on the four parameter equation pH=α+SpcH+JH+[H+]+ JOH-Kw/[H+] based on the Gran,s plots was used to obtain pH-readings in the concentration scale (pcH). The effect of the solvent on the protolytic constants was discussed.
Synthesis, Properties, and X-ray Crystal Structure of Copper(II) Complex with Bis[(2-pyridyl)methyl]-2-(2-pyridyl)ethylamine
Choi, Ki-Young ;
Journal of the Korean Chemical Society, volume 51, issue 1, 2007, Pages 31~35
DOI : 10.5012/jkcs.2007.51.1.031
The tripodal copper(II) complex [Cu(pmea)(H2O)](ClO4)2·H2O (1) (pmea = bis[(2-pyridyl)methyl]-2-(2-pyridyl)ethylamine) has been synthesized and structurally characterized by X-ray diffraction method. It crystallizes in the triclinic system P-1 with a = 9.9362(9), b = 15.7299(17), c = 18.0562(11) A, α = 68.760(8), β = 76.331(6), γ = 77.092(9)°, V = 2526.2(4) A3, Z = 2. Each copper atom reveals a distorted square pyramidal with three nitrogen atoms of the pmea ligand and water molecule occupying the basal plane and one nitrogen atom from the pyridine ring according the axial position. The cyclic voltammogram of 1 undergoes reversible one-electron oxidation to the CuIII and reversible one-electron reduction to the CuI.
Detection of Hepatitis B Virus Using Micro-PCR and Real-Time PCR Methods
Kang, Won ; Park, Sang-Bum ; Nam, Youn-Hyoung ; An, Young-Chang ; Lee, Sang-Hyun ; Jang, Won-Cheoul ; Park, Su-Min ; Kim, Jong-Wan ; Chong, Song-Chun ;
Journal of the Korean Chemical Society, volume 51, issue 1, 2007, Pages 36~42
DOI : 10.5012/jkcs.2007.51.1.036
Hepatitis B is a serious public health problem leading to chronic infection and liver cancer. Quantitation of circulating hepatitis B virus (HBV) is important for monitoring disease progression and for assessing the response to antiviral therapy. In this study, by using Real-Time PCR and novel Micro-PCR assay method, we measured HBV concentration in the clinical sample. A total of 120 serum samples from patients with HBV infection collected was in Dankook university hospital to compare the detection limit, sensitivity, specificity and reproducibility of the two assay methods. These findings of this study suggest that Micro-PCR and Real-Time PCR assay methods are comparable to each other in there detection limit, sensitivity, and reproducibility for HBV DNA quantitation. However, Micro-PCR assay is more efficient than Real-Time PCR method, because Real-Time PCR is not so time - consuming, technically easy and need to reagent of a small quantity. It will be useful for rapid and reliable clinical diagnosis of HBV in many countries.
In Vitro Stability of Liposomes Containing Newly Synthesized Glycolipid
Song, Chung-Kil ; Jung, Soon-Hwa ; Seong, Ha-Soo ; Cho, Sun-Hang ; Shin, Byung-Cheol ;
Journal of the Korean Chemical Society, volume 51, issue 1, 2007, Pages 43~50
DOI : 10.5012/jkcs.2007.51.1.043
Liposomes having particle size from several tens to hundreds nanometers are efficient carriers for injectable drug delivery. Enhancement of liposome stability in bloodstream has been studied because of its relatively short circulation time and fast clearance from human body by reticuloendothelial system (RES) in blood vessel. In this study, new disaccharide-1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE) derivatives in which lactose or sucrose as the disaccharide molecule was conjugated covalently to DSPE were synthesized. Liposomes of which surface had disaccharide molecules were prepared by incorporating the disaccharide-DSPE into liposomes as one of their lipid components. Particle size of the prepared liposomes was approximately 100 nm. The liposomes of which surface were modified with the disaccharide-DSPE showed -25 mV of zeta potential value due to the presence of hydroxyl groups on their surface, while the unmodified control liposomes showed -10 mV of zeta potential value. Loading efficiency of model drug, doxorubicin, into liposomes was about 90%. Stability of the disaccharide-modified liposomes in vitro was evaluated by monitoring the amount of protein adsorption and particle size of the liposomes in serum. Disaccharide-modified liposomes were more stable in serum than unmodified control liposomes or polyethyleneglycol (PEG)-modified liposomes due to less adsorption of serum protein and hence less increase of their particle size. The liposomes of which surface was modified with disaccharide-DSPE conjugate can be used as long-circulating carriers for drugs having high toxicity or short half-life time due to their enhanced stability in blood circulatory system.
Fatty Acid Profile Of Thiocyanate Utilizing Bacillus Brevis
Tm, Usha Mary ; Balasubramaniyan, S. ; Swaminathan, M. ;
Journal of the Korean Chemical Society, volume 51, issue 1, 2007, Pages 51~55
DOI : 10.5012/jkcs.2007.51.1.051
The fatty acid composition of thiocyanate utilizing Bacillus brevis isolated from carbonization wastewater was determined by Gas Chromatography and the results were analyzed. In addition to the saturated and unsaturated straight chain fatty acids this B. brevis strain contained a hydroxy fatty acid. The hydroxy fatty acids in general are shown to be interesting chemotaxonomic markers of bacteria. Cyclopropane fatty acids are totally absent in this strain. A comparison of the fatty acid composition of this strain with B-33 and B-34 strains of Bacillus brevis shows that there are deviations among these strains. The deviation in Bacillus brevis could be due to the stress effect of thiocyanate. This result supports that fatty acid synthesis depends highly on the environment.
Influences of Cognitive Conflict and Non-cognitive Variables Induced by Discrepant Event and Alternative Hypothesis on Conceptual Change
Kang, Hun-Sik ; Kwack, Jin-Ha ; Kim, You-Jung ; Noh, Tae-Hee ;
Journal of the Korean Chemical Society, volume 51, issue 1, 2007, Pages 56~64
DOI : 10.5012/jkcs.2007.51.1.056
This study examined the influences of cognitive conflict and anxiety induced by a discrepant event and an alternative hypothesis, attention, and effort on conceptual change. Two hundred three students having misconceptions about density were selected from 462 seventh graders based on the results of a preconception test. Tests of cognitive responses and anxiety to a discrepant event were administered before and after presenting an alternative hypothesis. Computer-assisted instruction (CAI) was then provided to students as a conceptual change intervention. Tests assessing attention and effort allocated to the CAI, and conceptual understanding were administered as posttests. Cognitive conflict induced by a discrepant event was found to increase after presenting an alternative hypothesis. Pre-cognitive conflict induced by only a discrepant event exerted a direct effect on post-cognitive conflict induced by a discrepant event and an alternative hypothesis. Post-cognitive conflict had a direct effect on conceptual change. Pre-anxiety decreased after presenting an alternative hypothesis. Pre-anxiety influenced post-anxiety, and this influenced on conceptual change via effort negatively. Attention had a direct effect as well as an indirect effect on conceptual change via effort. These results suggest that the strategy presenting both a discrepant event and an alternative hypothesis to students in concept learning could facilitate conceptual change by inducing more cognitive conflict or active participation of students through the decrease of anxiety than that presenting a discrepant event only.
Examining the Concept of Matter in the 7th National Science Curriculum
Hong, Mi-Young ; Jeon, Kyung-Moon ;
Journal of the Korean Chemical Society, volume 51, issue 1, 2007, Pages 65~72
DOI : 10.5012/jkcs.2007.51.1.065
The purpose of this study was to examine the 7th national science curriculum (chemistry domain) regarding the meanings of ‘mulgil' (Korean), the particulate nature of matter, and the state of matter. It was found that the term of ‘mulgil' was being used vaguely as representing material, matter, or substance without clear definition. This was problematic by reason that it could hinder students from having the concept of substance. Regarding the particulate nature of matter, molecule was introduced as a basic unit of matter at grade 7, prior to atom and ion, which were introduced at grade 9 and 10, respectively. It is necessary to reconsider the sequence of each particle concept to provide students with more consistent and comprehensive understanding of structure of matter. In the case of change of state, key concepts such as conservation of matter or reversibility were omitted in the curriculum document, and explanations based on various aspects of particles were somewhat insufficient. The concept of matter is fundamental to chemistry, and we must recognize it as a concept that needs to be taught clearly. Implications for curriculum revision were discussed.
Survey of Chemistry Teachers' Perceptions and Teaching Style on Chemistry I Course
Lee, Eun-Ju ; Cho, Young-Ja ; Kim, Eun-Suk ; Ryu, Ran-Yeong ; Kim, Dong-Jin ; Park, Kuk-Tae ;
Journal of the Korean Chemical Society, volume 51, issue 1, 2007, Pages 73~81
DOI : 10.5012/jkcs.2007.51.1.073
The purpose of this study was to find out chemistry teachers' perceptions on the aims and characteristics of the chemistry I course from the 7th national curriculum by means of investigating how frequently particular learning contents were selected and what the teachers' teaching styles were in order to find out how effectively teachers were working with the 7th national curriculum in teaching. For this study, data was collected by means of questionnaires, which was answered by 44 chemistry teachers in 40 different high schools. Results from this study are as follows: As for the perception on the aim and characteristics of chemistry I course, many chemistry teachers have already perceived that the aim of the course was to promote democratic citizens with the knowledge of chemistry. And the most appropriate way of teaching chemistry I course was inquiry-centered teaching such as experiment-practice and inquiry-discussion. However, these perceptions were not reflected when they actually taught students in the classroom. Instead, most of the class was concepts learning and there were a lot of differences in selecting learning contents among chemistry teachers. Furthermore, although chemistry I course was considered a good subject to make students have interest and curiosity in chemistry, it was not appropriate to make students understand the concepts of chemistry. Therefore, learning contents in chemistry I course need to improve. In conclusion, as the goal of 7th national curriculum of chemistry I course was to emphasize inquiry teaching, inquiry based teaching should be practiced in the class. Moreover, sufficient teacher training should be accompanied and alternative additional teaching contents should be developed. Finally teachers' experiences should be reflected in the national curriculum when it is revised.
The Influences of Reciprocal Peer Tutoring Strategy and Field Independence-Dependence in Instruction Enhancing Student Questions by Using Weekly Reports
Kang, Hun-Sik ; Kwon, Eun-Kyung ; Noh, Tae-Hee ;
Journal of the Korean Chemical Society, volume 51, issue 1, 2007, Pages 82~92
DOI : 10.5012/jkcs.2007.51.1.082
This study investigated the influences of reciprocal peer tutoring strategy and field independencedependence in the instruction enhancing student questions by using weekly reports. Seventh graders (N=152) from a middle school were assigned to WR (weekly reports) and WR-RPT (weekly reports-reciprocal peer tutoring) groups. Students were taught about ‘three states of matter', ‘motion of molecules', and ‘change of states and thermal energy for eighteen class hours and wrote weekly reports six times for the period. The students in the WR-RPT group also conducted reciprocal peer tutoring with the questions of weekly reports which they wrote. The results revealed that the scores of the WR-RPT group were significantly higher than those of the WR group in a conception test regardless of students' field independence-dependence. The field dependent students in the WR-RPT group performed better in an achievement test than those in WR group, while there was no significant difference for the field independent stu dents between the two groups. Additionally, field independent students in each group scored significantly higher than field dependent students in the two tests. Many students, especially having more field independence in the WR-RPT group, perceived WR-RPT positively.
An Analysis and Improvement of the Experiments for Comparing Properties of a Mixture with a Compound of Iron and Sulfur in the Middle School Science Textbooks
Park, Kyong-Hee ; Kang, Seong-Joo ;
Journal of the Korean Chemical Society, volume 51, issue 1, 2007, Pages 93~100
DOI : 10.5012/jkcs.2007.51.1.093
The purposes of this study were to analyze problems in the experiments for comparing properties of a mixture with a compound of iron and sulfur and then to suggest the improved experiments. For this study, the experimental methods in 9th science textbooks described were analyzed and middle school science teachers were asked to conduct the experiment according to the process of the textbook and to point problems of the experiment. Two alternative experiments, which improves the problems of the toxic and provocative experiment and of distinction between a mixture and a compound by magnetic properties, were proposed. The two experiments were applied to the 10 science teachers and 60 students from a “S” middle school. They responded that the experiments were suitable for comparing properties of a mixture and a compound and helpful to understand the concept.
DFT Studies on the Copper(II) Complexes of DNA Bases
Lee, Gab-Yong ;
Journal of the Korean Chemical Society, volume 51, issue 1, 2007, Pages 101~105
DOI : 10.5012/jkcs.2007.51.1.101
An Efficient Synthesis of 2,3-Dihydro-2-phenyl-4-quinolones from 2'-Aminoacetophenones
Lee, Jae-In ; Jung, Hye-Jin ;
Journal of the Korean Chemical Society, volume 51, issue 1, 2007, Pages 106~110
DOI : 10.5012/jkcs.2007.51.1.106