• Journal of the Korean Chemical Society
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• v.53 no.1
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• pp.34-41
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• 2009

A new series of hydrazone derivatives were synthesized from 4-(2-chloroethyl)semicarbazide and their antiproliferative activity against human brain (U251) and liver (Hepg2) carcinoma cell lines were evaluated. The hydrazone compounds are benzaldehyde (2a-2g), acetophenone (3a-3f), and 3-formylindole derivatives (4a-4d). Among the acetophenone derivatives, 3e (p-methoxy substituted) and 3f (p-nitro substituted) showed the highest cytotoxic activity against Hepg2 cell line (I$C_{50}$ = 6 and 8 $\mu$g/ml, respectively). Among the 3-formylindole derivatives, 4a (hydrazone of 3-formylindole itself) showed a pronounced cytotoxic activity against both U251 (I$C_{50}$ = 21 $\mu$g/ml) and Hepg2 (I$C_{50}$ = 7 $\mu$g/ml).

• Applied Biological Chemistry
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• v.41 no.1
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• pp.99-103
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• 1998

Triazolopyrimidine sulfonanilide (TP) derivative is one of excellent herbicide compounds. We have synthesized three classes of a new sulfonamide derivative (TPP) as Acetolactate synthase (ALS) inhibitors, in which the benzene ring in TP skeleton was converted to substituted pyrimidyl ring and examined their inhibitory activities on barley for ALS. $I_{50}$ values of the inhibitors ranged from 0.005 to 2 mM. Comparing the $I_{50}$ value of each class of TPP derivatives, the substituents in pyrimidine and triazolopyrimidine ring were found to affect the degree of ALS inhibition. TPP with substituted methyl group in pyrimidine ring showed higher inhibitory activity than that with methoxy group, while the substitution of the cyclopentano group in triazolopyrimidine ring gave very large inhibitory activity than that of methyl group. The present study established that variation of the electron density by substitution at heterocyclic ring is a very important factor for ALS inhibition, but showed no dependence on steric effect by substituents.

• Journal of the Korean Chemical Society
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• v.43 no.6
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• pp.720-727
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• 1999

The science teachers' perceptions and the status of formative assessment in science teaching were identified through a questionnaire. The majority of teachers thought that the most important goal of assessment in education was to identify to what extent pupils achieved learning objectives. They suggested that formative assessment was the most appropriate method regardless of the purposes of assessment. They thought that formative assessment was an assessment carried out at the end of lesson to identify to what extent pupils achieved learning objectives. The teachers stressed the need for formative assessment to identify what pupils achieved. But they carried out formative assessment about once a week and there were very few teachers carrying out formative assessment during the lesson. They responded that it was difficult to carry out formative assessment because of large class size, lack of time and difficulty in preparation. And they used the information from formative assessment to judge the level of attainment.

• Journal of the Korean Chemical Society
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• v.59 no.5
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• pp.434-444
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• 2015

Inquiry-based experiments provide opportunities to understand scientific knowledge and acquire nature of science. In this study, the difficulties which pre-service teachers experienced in inquiry-based experiment class were investigated and analyzed. Twenty-two pre-service teachers attended course designed as ‘ill-structured inquiry’ for 13 weeks, and researchers investigated their difficulties by questionnaires and interview. They showed difficulties mostly in designing experiment and interpretation and also in understanding inquiry purpose, lack of prior knowledge, confidence in inquiry performance, and understanding of experimental instruments and facilities. As a result, it is necessary to provide opportunities to engage in inquiries and environments to properly instruct pre-service teachers the inquiry ability in college of education.

• Applied Chemistry for Engineering
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• v.29 no.5
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• pp.519-523
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• 2018

Cyclodextrins are a class of oligosaccharides having an extremely low toxicity, so that they have been used for the formation of host-guest complexes and removal of toxic gases or molecules. In this study, the subtle phenomenon associated with the formation of host-guest complexes between cyclodextrin and toxic molecules (methyl paraben) was experimentally investigated. First, the formation of cyclodextrin-methyl paraben complexes was monitored by UV/Vis spectroscopy as a function of the cyclodextrin concentration. Secondly, the electrochemical measurement was performed with the surface engineered Au electrode having cyclodextrin molecules on the Au substrate. The sensing signal derived from the addition of methyl paraben solution into the Au surface was measured delicately. This study can be informative for future applications such as sensors.

• Journal of the Korean Chemical Society
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• v.46 no.4
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• pp.377-384
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• 2002

In this study, the effect of cooperative computer-assisted instruction upon students' conceptual under-standing,application ability, and learning motivation were investigated by a previous achievement level. The treatment and the control groups (2 classes) were selected from a middle school in Seoul, and taught about the motion of molecule for 5 class periods. Prior to the instructions, a learning motivation test was administered and used as covariate. The scores of a previous achievement test were also used as covariate. The scores of the mid-term science examination were used as blocking variable. After the instructions, the conceptions test, the application test, and the learning motivation test were administered. Two-way ANCOVA results revealed that there were no significant differences in the scores of the con-ceptions test and the application test. However, the scores of the treatment group were found to be significantly higher than those of the control group in the learning motivation test.

• Journal of the Korean Chemical Society
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• v.47 no.6
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• pp.625-632
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• 2003

In this study, the effects of two types of reward methods in cooperative learning were investigated upon students' achievement, learning motivation, perceptions of learning environment and perceptions of reward methods. Seventh graders (N=61) were selected from a co-ed middle school in Seoul, and were taught about 'three states of matter', 'motion of molecules' and 'change of state and thermal energy' for 14 class hours. Reward methods were classified into task-oriented reward and performance-oriented reward. The results revealed that high-level students performed better in the task-oriented reward group, and low-level students performed better in the performance-reward group for the 'application' subcategory of the achievement test. The scores of attention and relevance in learning motivation and task orientation, involvement, and order and organization in perceptions of learning environment test were significantly higher in the task-oriented reward group than those in the performance-oriented reward group.

• Journal of the Korean Chemical Society
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• v.46 no.5
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• pp.450-468
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• 2002

As the computer is popularized in individual and society, it is using in a many of area. In particular, there are many materials to learn a science knowledge using multimedia through computer. Many of them are web-based learning materials, which are developed by Java or Flash. Since the technology of the representation, storage, com-putation and communication in computer make progress, the environment of education is also developed. Especially, the internet and VR technology will cause the education to change. A key feature of VR is real-time interactivity, in that the computer is able to detect student input and instantaneously modify the virtual world. It is reported that using the VR simulation in chemistry education can increase student engagement in class, promote understanding of basic chem-ical principles, and augment laboratory experience. In this study, application way of the virtual reality technology in chemistry education is examined.

• Korean Journal of Environmental Agriculture
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• v.30 no.3
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• pp.323-329
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• 2011

BACKGROUND: The conazoles, difenoconazole, diniconazole, hexaconazole, penconazole and tetraconazole are a large class of synthetic fungicides used extensively for foliage and seed treatments in agricultural crops. The extensive use of conazoles has brought concerns on the potentiality of environmental contamination and toxicity. Thus studies on the development of methods for monitoring the conazoles are required. METHODS AND RESULTS: A modified quick, easy, effective, rugged and safe (QuEChERS) method was involved in sample preparation. Quadrapole time of flight mass spectrometer (Q-TOF MS) in electron spray ionization (ESI) mode was employed to determine conazoles in garlic samples. The limit of detection (LOD) and limit of quantification (LOQ) of conazoles by Q-TOF-MS ranged from 0.001 to 0.002 mg/L and 0.002 to 0.005 mg/L, respectively. Q-TOF-MS analysis exhibited less than 2.6 ppm error of accurate mass measurements for the detection of conazoles spiked at 0.05 mg/L in garlic matrix. Recovery values of conazoles fortified in garlic samples at 0.02, 0.05 and 0.1 mg/L were between 79.2 and 106.2% with a maximum 11.8% of standard deviation. No detectable conazoles were found in the domestic market samples by using the Q-TOF-MS method. CONCLUSION(s): High degree of confirmation for conazoles by accurate mass measurements demonstrated that Q-TOF-MS analysis combined with a QuEChERS method may be applicable to simultaneous determination of conazoles in garlic samples.

• Analytical Science and Technology
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• v.36 no.5
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• pp.236-249
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• 2023

Carbon dioxide (CO₂) capture and storage is a critical issue for mitigating climate change. Porous aromatic Schiff base complexes have emerged as a promising class of materials for CO₂ capture due to their high surface area, porosity, and stability. In this study, we investigate the potential of Schiff base complexes as an effective media for CO₂ storage. We review the synthesis and characterization of porous aromatic Schiff bases materials complexes and examine their CO₂ sorption properties. We find that Schiff base complexes exhibit high CO₂ adsorption capacity and selectivity, making them a promising candidate for use in carbon capture applications. Moreover, we investigate the effect of various parameters such as temperature, and pressure on the CO₂ adsorption properties of Schiff base complexes. The Schiff bases possessed tiny Brunauer-Emmett-Teller surface areas (4.7-19.4 m²/g), typical pore diameters of 12.8-29.43 nm, and pore volumes ranging from 0.02-0.073 cm³/g. Overall, our results suggest that synthesized complexes have great potential as an effective media for CO₂ storage, which could significantly reduce greenhouse gas emissions and contribute to mitigating climate change. The study provides valuable insights into the design of novel materials for CO₂ capture and storage, which is a critical area of research for achieving a sustainable future.