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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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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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Synthesis, Characterization and Correlation Analysis in Styryl 6-Methoxy-2-Naphthyl Ketones
Thirunarayanan, G. ;
Journal of the Korean Chemical Society, volume 51, issue 2, 2007, Pages 115~124
DOI : 10.5012/jkcs.2007.51.2.115
A series of α, β-unsaturated ketones are synthesized by Crossed - Aldol condensation reaction, from ecofriendly 6-methoxy-2-naphthyl ketones and substituted benzaldehydes under solvent free conditions using silica-sulfuric acid as a catalytic reagent. The yields of ketones are more than 90% and the catalyst was reusable for further run. There is no appreciable decrease in the yield of product and the activity of catalyst. These chalcones were characterized by their physical constants and spectral data (IR, 1H-, 13C-NMR and Mass). These spectral data are subjected to correlate various Hammett substituent constants with single and multiparameter correlation equations. From the results of statistical analysis the influence of electronic effects of substituents on the spectral data of the ketones were explained.
Numerov-Cooley Method on a Potential of NO Molecule
Cho, Seon-Woog ;
Journal of the Korean Chemical Society, volume 51, issue 2, 2007, Pages 125~128
DOI : 10.5012/jkcs.2007.51.2.125
In applying Numerov-Cooley method, Excel tool ‘Solver' is used to match those two wave functions propagated inward and outward, respectively. It is numerically confirmed that the same eigenvalue is obtained by using the average of two energy values of each inward and outward wave functions. This method is applied to a NO molecule potential, and we calculated the variations of the average bond distance and tunneling for a given vibrational energy. It is found that the average bond lengths increase proportionately to the vibrational energy, while the tunneling is not so sensitive to the energy changes. Rather substantial amount of tunnel effect is found for every vibrational state.
Thermodynamic Study on the Micellar Properties of TTAB/Brij 35 Mixed Surfactant Systems
Gil, Han-Nae ; Lee, Byung-Hwan ;
Journal of the Korean Chemical Society, volume 51, issue 2, 2007, Pages 129~135
DOI : 10.5012/jkcs.2007.51.2.129
The critical micelle concentrations (CMC) and the counter ion binding constants (B) in a micellar state of the mixed surfactant systems of Tetradecyltrimethylammonium bromide (TTAB) with Polyoxyethylene(23) lauryl ether (Brij 35) in water were determined as a function of α1 (the overall mole fraction of TTAB) by the use of electric conductivity method and surface tensiometer method from 15 oC to 35 oC. Values of thermodynamic parameters (ΔGom, ΔHom, and ΔSom) for the micellization of TTAB/Brij 35 mixtures were calculated and analyzed from the temperature dependence of CMC values. The results say that the measured values of ΔGom are all negative at the whole measured condition but the values of ΔSom and ΔHom are positive or negative, depending on the measured temperature and α1.
Discrete Dipole Approximation Calculation of the Extinction Spectra of Gold-Silver Alloy Nanoparticles
Lee, Hee-Mi ; Chandra, Saha Leton ; Jang, Joon-Kyung ;
Journal of the Korean Chemical Society, volume 51, issue 2, 2007, Pages 136~140
DOI : 10.5012/jkcs.2007.51.2.136
By using the discrete-dipole approximation, we computed the extinction spectrum of a gold-silver alloy nanoparticle. We have examined how the surface plasmon resonance changes with respect to the variation in the composition of the alloy particle. As the fraction of silver increases for a 10nm particle, the peak position of the extinction spectrum blue-shifts linearly. The intensity of the peak however increases exponentially with increasing the silver fraction. These results are in accord with the previous experimental results.
Determination of Copper Ion with 2-Mercaptobenzimidazol Immobilized on Surfactant-Coated Alumina
Absalan, G. ; Goudi, A.Aghaei ;
Journal of the Korean Chemical Society, volume 51, issue 2, 2007, Pages 141~146
DOI : 10.5012/jkcs.2007.51.2.141
The present paper describes a procedure for separation, preconcentration and determination of trace amount of copper in natural water samples by using 2-mercaptobenzimidazol as the complexing agent. The proposed method is based on the surfactant aggregation formed on γ-alumina by mixing sodium dodecyl sulfate and γ-alumina in water; 2-mercaptobenzimidazol was incorporated into inner hydrophobic part of produced ad-micelles in acidic media to produce an assemble suitable for preconcentration and determination of copper ion. Optimum experimental conditions for adsorption of μg/ml levels of copper ions from aqueous solution by the adsorbent have been reported. The copper ions were quantitively adsorbed by the sorbent over the pH range of 7.1-8.0 and were quantitatively desorbed afterward by using sulfosalycilic acid as the eluent. The determination of copper was not interfered in the presence of common metal ions. The procedure was applied for analysis of river water sample. Relative standard deviation was found to be 4.91%.
Simple and Selective Flow Injection Catalytic Determination of Ruthenium with Spectrophotometric Detection
Rezaei, Behzad ; Majidi, Najmeh ;
Journal of the Korean Chemical Society, volume 51, issue 2, 2007, Pages 147~153
DOI : 10.5012/jkcs.2007.51.2.147
A simple, selective and highly sensitive flow injection catalytic method was presented for determination of ruthenium based on its catalytic effect on the oxidation of pyronin B by periodate in pH=1.0. The reaction rate is controlled specrophotometricaly by monitoring the dye absorbance at 555 nm. The optimized conditions make it possible to determine ruthenium in the ranges of 0.1-10.0 ng/mL (r2=0.9982) and 10.0-50.0 ng/mL (r2=0.9934) with a detection limit of 0.04 ng/mL and a sample rate of 30±5 samples/h. Relative standard deviation for the results of five replicate measurements does not exceed 1.44%. The proposed method has been successfully applied for quantitation of ultra trace amounts of ruthenium in some environmental and biological samples.
Enhanced Degradation of Quinoline by Immobilized Bacillus Brevis
S., Balasubramaniyan ; M., Swaminathan ;
Journal of the Korean Chemical Society, volume 51, issue 2, 2007, Pages 154~159
DOI : 10.5012/jkcs.2007.51.2.154
Biodegradation of Quinoline by free and immobilized Bacillus brevis has been investigated. The rate of quinoline degradation by immobilized Bacillus brevis on coconut shell carbon is faster than the rate by the microorganism immobilized on foam pieces and free cells. A complete removal of 100 ppm of Quinoline in the sample was achieved at a hydraulic retention time of 20 hours with the biocatalyst prepared by immobilizing Bacillus brevis onto coconut shell carbon. The biocatalyst had a reasonable shelf life and desirable recycle capacity.
Synthesis of Aminofuroxan Derivatives for the Alkyne Formation on Solid Surface and e-Beam Mediated Fragmentation in Gas Phase
Heo, Jeong-Mu ; Kim, Gi-Young ; Hwang, Kwang-Jin ;
Journal of the Korean Chemical Society, volume 51, issue 2, 2007, Pages 160~164
DOI : 10.5012/jkcs.2007.51.2.160
Aminofuroxan derivatives 3 and 4 were prepared by the reaction of chlorofuroxan 2 with butyl and benzyl amines, respectively. E-beam mediated fragmentation of aminofuroxans 3, 4 in mass spectrometer was analyzed in a view of the corresponding alkyne formation.
Separation of Caffeine and Catechin Compounds from Green Tea by Quercetin Molecular Imprinted Solid-Phase Extraction
Jin, Yin-Zhe ; Row, Kyung-Ho ;
Journal of the Korean Chemical Society, volume 51, issue 2, 2007, Pages 165~170
DOI : 10.5012/jkcs.2007.51.2.165
In this work, caffeine and some catechin compounds such as +C, EGC and EGCG were extracted from green tea using quercetin molecular imprinted polymers in solid-phase extraction. For synthesis of MIP, quercetin as the templates, MAA as the monomer, EGDMA as the crosslinker and AIBN as the initiator were used. For extraction of caffeine and catechin compounds from green tea, the solid-phase extractions of a load followed by wash and elution procedures were done with water, methanol and methanol:acetic acid=90:10 (vol.%) as the solvents, respectively. HPLC analysis (C18 column, 5 μm, 250×4.6 mm) with the mobile phase of methanol:water=40:60 (vol.%) at a flow rate of 0.5 ml/min was adopted for the quantitative determination. By solid-phase extraction, the resolutions of caffeine and some catechin compounds from green tea were increased. The quercetin-MIP had higher selectivity to +C compounds.
Novel Conductive Paste based on Cellulose Acetate Butyrate
Kim, Tae-Hyun ;
Journal of the Korean Chemical Society, volume 51, issue 2, 2007, Pages 171~177
DOI : 10.5012/jkcs.2007.51.2.171
Polymer-based electrically conductive pastes have been used to make the conductive paths between voltage sources and devices. The pastes used for these applications consist of two main components: a polymer binder and a conductive filler. Having both low viscosity and good metal-encapsulating properties, cellulose acetate butyrate (CAB) was regarded to be a good candidate as a binder for the conductive paste. We have prepared a formulation for a novel conductive paste based on CAB. Preliminary studies showed that this conductive paste revealed stable conductivity, together with uniform coating and flexibility.
Synthesis of Borosilicate Zeotypes by Steam-assisted Conversion Method
Mansour, R. ; Lafjah, M. ; Djafri, F. ; Bengueddach, A. ;
Journal of the Korean Chemical Society, volume 51, issue 2, 2007, Pages 178~185
DOI : 10.5012/jkcs.2007.51.2.178
Intermediate pentasil borosilicate zeolite-like materials have been crystallized by a novel method named steam-assisted conversion, which involves vapor-phase transport of water. Indeed, amorphous powders obtained by drying Na2O.SiO2.B2O3.TBA2O gels of various compositions using different boron sources are transformed into crystalline borosilicate zeolite belonging to pentasil family structure by contact with vapors of water under hydrothermal conditions. Using a variant of this method, a new material which has an intermediate structure of MFI/MEL in the ratio 90:10 was crystallized. The results show that steam and sufficiently high pH in the reacting hydrous solid are necessary for the crystallization to proceed. Characterization of the products shows some specific structural aspects which may have its unique catalytic properties. X-ray diffraction patterns of these microporous crystalline borosilicates are subjected to investigation, then, it is shown that the product structure has good crystallinity and is interpreted in terms of regular stacking of pentasil layers correlated by inversion centers (MFI structure) but interrupted by faults consisting of mirror-related layers (MEL structure). The products are also characterized by nitrogen adsorption at 77 K that shows higher microporous volume (0.160 cc/g) than that of pure MFI phase (0.119 cc/g). The obtained materials revealed high surface area (~600 m2/g). The infrared spectrum reveals the presence of an absorption band at 900.75 cm-1 indicating the incorporation of boron in tetrahedral sites in the silicate matrix of the crystalline phase.
The Effects of Concept Mapping Strategy in the Undergraduate General Chemistry Course
Koh, Han-Joong ; Doh, Eun-Jeong ; Kang, Suk-Jin ;
Journal of the Korean Chemical Society, volume 51, issue 2, 2007, Pages 186~192
DOI : 10.5012/jkcs.2007.51.2.186
In this study, the effects of concept mapping on the preservice elementary teachers' achievement, conceptual understanding, anxiety toward science, and science teaching efficacy belief were investigated in the undergraduate general chemistry course. The aptitude-treatment interaction (ATI) between preservice teachers' learning approach and concept mapping strategy was also investigated. Sixty-nine freshmen from a university of education were assigned to a control group and a treatment group. Tests regarding students' learning approach, anxiety toward science, and science teaching efficacy belief were administered as pretests. Treatment lasted for 9 weeks. In every class, students in the treatment group constructed concept maps, while those in the control group solved the problems of the textbook after the lecture. After the instructions, tests of achievement, conceptual understanding, anxiety toward science, and science teaching efficacy beliefs were administered. The results indicated that students in the treatment group significantly outperformed those of the control group in the achievement test. In the conceptual understanding and the science teaching efficacy beliefs, however, no statistically significant differences were found between two groups. Students of the treatment group showed significantly higher anxiety than their counterpart in the test of anxiety toward science. No aptitudetreatment interaction between students' learning approach and the concept mapping strategy was found.
The Effects of Situational Context Feedbacks in Chemistry Learning with Computer-Assisted Instruction
Kim, Kyung-Sun ; Chung, Kyoung-Jin ; Cha, Jeong-Ho ; Kang, Yi-Young ; Noh, Tae-Hee ;
Journal of the Korean Chemical Society, volume 51, issue 2, 2007, Pages 193~200
DOI : 10.5012/jkcs.2007.51.2.193
This study investigated the effects of situational context feedback in CAI upon students' conceptual understanding, science learning motivation, and the perception of CAI. Seventh graders (N = 114) from a coed middle school in Incheon were assigned to the situational context feedback CAI (SCF-CAI), the feedback CAI (F-CAI) and the CAI groups, and were taught about ‘three states of matter' and ‘motion of molecules' for 8 class hours. Prior science achievement test score used as a blocking variable. Two-way ANCOVA results revealed that the conceptual understanding test scores of the SCF-CAI group were significantly higher than those of the other groups. For the higher achievers, the scores of the F-CAI group in science learning motivation test were significantly higher than those of the CAI group. However, there was no significant difference among the lower achievers of three groups. The higher achievers in the SCFCAI and the F-CAI groups perceived the CAI more positively than those of the CAI group. The lower achievers in the FCAI group perceived the CAI more negatively than those of the other groups. Educational implications are discussed.
Influences of Current Education Programs for Preservice Chemistry Teachers upon Preservice Science Teachers' Self-Images as Science Teachers
Kang, Hun-Sik ; Shin, Suk-Jin ; Cha, Jeong-Ho ; Han, Jae-Young ; Noh, Tae-Hee ;
Journal of the Korean Chemical Society, volume 51, issue 2, 2007, Pages 201~212
DOI : 10.5012/jkcs.2007.51.2.201
This study examined the influences of current education programs for preservice chemistry teachers upon preservice science teachers' self-images as science teachers by using Draw-A-Science-Teacher-Test Checklist (DASTT-C). Seventy-two juniors and fifty-three seniors were selected from the department of chemistry education or department of science education (chemistry major) in three colleges of education. DASTT-C was administered to the juniors before having science education courses, and to the seniors before and after teaching practices. The results revealed that preservice science teachers' self-images as science teachers were more ‘teacher-centered' than ‘student-centered'. Only a few preservice science teachers exhibited ‘student-centered' images after having science education courses including the contents on constructivism. The self-images of some preservice science teachers even changed from ‘student-centered' to ‘teacher-centered' after having teaching practices. Many preservice science teachers answered that the main factors affected to their self-images as science teachers were prior teaching-learning experiences and/or the lim itations in the real situations. Educational implications of these findings are discussed.
The Effect of Science History Program Developed by Genetic Approach on Student's Conception toward Particulate Nature of Matter and Understanding about the Nature of Science
Yoo, Mi-Hyun ; Yeo, Sang-Ihn ; Hong, Hun-Gi ;
Journal of the Korean Chemical Society, volume 51, issue 2, 2007, Pages 213~222
DOI : 10.5012/jkcs.2007.51.2.213
In this study, science history program was developed to enhance student's concepts toward the particulate nature of matter and the understanding about the nature of science. And the effects of its application was investigated in the lesson of ‘Composition of Matter' in middle school science class. This science history program was based on genetic approach and included the contents from the old Greek natural philosophers to Avogadro. Before instruction, the test of understanding about nature of science was administered, and the science scores of the previous course were obtained, which were used as covariates. During 24 class hours, this study was conducted with two classes(experimental and comparison group) in a middle school in Seoul. The experimental group was received lessons by science history programs and the comparison group was received traditional lessons. After instruction, the scientific concept test, the test of understanding about nature of science were administered. The result of this study indicates that the scientific concept scores of experimental group were significantly higher than comparison group at p <.01 level of significance. It means that the students in experimental group has more sound conceptions about the particulate nature of matter and less mis conceptions about matter than the students in comparison group. However, there was no significant difference between two groups in the score of understanding about the nature of science.