• Bulletin of the Korean Chemical Society
• /
• v.15 no.7
• /
• pp.534-537
• /
• 1994

A new metabolite 2 of bastadin class and the previously reported bastadins 3 and 4 were isolated from the sponge Ianthella basta collected in Indonesia.

• Journal of the Korean Chemical Society
• /
• v.48 no.3
• /
• pp.291-299
• /
• 2004

The purpose of this study is to investigate views of high school students' learning of chemistry as one aspect of conceptual ecology. The results of this study will help us expand our understanding of conceptual change as it is used to evaluate learners. I made use of an interpretative research design based on principles of naturalistic inquiry. The participants in this study were six sophomore students. The picture of a chemistry class we draw from analyzing data is a play on stage with little interaction. Students accept passive and difficult-to-modify views of the learner roles that they should play in the chemistry classroom. Students identified chemistry classes as conservative places. 'Transmission' seems to remain the persistent and dominant classroom cultural dynamic for both the teaching and learning of chemistry. Students should understand about learning processes, and how to play, monitor, evaluate and regulate them. Students should experience the plausibility and fruitfulness of learning chemistry, and it will help students to feel a "love of learning chemistry." As students change their views of learning chemistry, it will help to improve their learning and to experience conceptual change in chemistry learning.

• YAKHAK HOEJI
• /
• v.42 no.3
• /
• pp.302-306
• /
• 1998

In the previous study we described the antitumor activity of GLB, a protein-polysaccharide fraction of the growing tips of Ganoderma lucidum, against sarcoma 180 solid tu mor in ICR mice. In this study we investigated the stimulatory activity of GLB on macrophages. When analyzed using a flow cytometer, GLB ($100{\mu}g/ml$) was found to increase the phagocytic activity of the BALB/c mouse peritoneal macrophages as well as chicken macrophage BM2CL cells against FITC-labeled C.albicans by 55.2% and 21.2%, respectively. GLB also increased the spreading and the expression of MHC class II molecules of BM2CL cells as well as the mouse peritoneal macrophages. From these results, it is clear that GLB is a strong stimulator to the macrophages.

• Proceedings of the Korean Society of Dyers and Finishers Conference
• /
• 2004.11a
• /
• pp.274-275
• /
• 2004

The majority of dyes belong to the chromophoric class known as donor-acceptor systems, the essential structural feature of such systems being the presence of one or more electron donating groups conjugated to one or more electron withdrawing groups via an unsaturated bridge. The indigo molecule may be formally divided into two identical electron donor/acceptor subsystems, each containing an add number of pi electrons, two subsystems being joined by carbon-carbon double bond. Indigoid type dyes which show a strong colour change on protonation or dissociation have many potential functional applications, for example as analytical pH indicators, solvent polarity indicators, and in various imaging and reprographic systems.

• Genomics & Informatics
• /
• v.16 no.3
• /
• pp.44-51
• /
• 2018

Fluoroquinolone (FQ) antibiotics are an important class of synthetic antibacterial agents. These are the most extensively used drugs for treating bacterial infections in the field of both human and veterinary medicine. Herein, the antibacterial and pharmacological properties of four fluoroquinolones: lomefloxacin, norfloxacin, ciprofloxacin, and ofloxacin have been studied. The objective of this study was to analyze the antibacterial characteristics of the different fluoroquinolones. Also, the pharmacological properties of the compounds including the Lipinski rule of five, absorption, distribution, metabolism, and excretion, LD50, drug likeliness, and toxicity were evaluated. We found that among all four FQ molecules, ofloxacin showed the highest antibacterial activity through in silico assays with a strong interaction (-38.52 kJ/mol) with the antibacterial target protein (topoisomerase-II DNA gyrase enzyme). The pharmacological and pharmacokinetic analysis also showed that the compounds ciprofloxacin, ofloxacin, lomefloxacin and norfloxacin have good pharmacological properties. Notably, ofloxacin was found to possess an IGC50 (concentration needed to inhibit 50% growth) value of $0.286{\mu}g/L$ against the Tetrahymena pyriformis protozoa. It also tested negative for the Ames toxicity test, showing its non-carcinogenic character.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.1
• /
• pp.146-150
• /
• 2010

A distinguished class of hydrophobic ionic liquids bearing a Br${\o}$nsted acidic character derived from amide-like compounds were prepared by a neutralization reaction of N,N-diethylformamide, N,N-dibutylformamide, 1-formylpiperidine, and $\varepsilon$-caprolactam with trifluoroacetic acid and physical absorptions of $CO_2$ in these ionic liquids were demonstrated and evaluated. $CO_2$ solubilities in these ionic liquids were influenced by the molecular structure of the cation and were apparently increased with the molar volume. Comparison based on a volume unit reveals that $CO_2$ solubilities in these liquids are relatively higher than those in imidazolium-based ionic liquids. Henry's coefficients calculated from low-pressure solubility tests at 313 to 333 K were used to derive the thermodynamics quantities. Enthalpy and entropy of solvation may share equal contributions in solubility.

• Toxicological Research
• /
• v.33 no.4
• /
• pp.299-304
• /
• 2017

Thallium and its compounds are a class of highly toxic chemicals that cause wide-ranging symptoms such as gastrointestinal disturbances; polyneuritis; encephalopathy; tachycardia; skin eruptions; hepatic, renal, cardiac, and neurological toxicities; and have mutagenic and genotoxic effects. The present research aimed to evaluate the efficacy of the chelating agents deferasirox (DFX) and deferiprone (L1) in reducing serum and tissue thallium levels after the administration of thallium (III), according to two different dosing regimens, to several groups of Wistar rats for 60 days. It was hypothesized that the two chelators might be more efficient as a combined therapy than as monotherapies in removing thallium (III) from the rats' organs. The chelators were administered orally as either single or combined therapies for a period of 14 days. Serum and tissue thallium (III) and iron concentrations were determined by flame atomic absorption spectroscopy. Serum and tissue thallium (III) levels were significantly reduced by combined therapy with DFX and L1. Additionally, iron concentrations returned to normal levels and symptoms of toxicity decreased.

• Journal of the Korean Chemical Society
• /
• v.51 no.1
• /
• pp.73-81
• /
• 2007

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.

• Applied Chemistry for Engineering
• /
• v.21 no.4
• /
• pp.366-371
• /
• 2010

Accompanying the rapid advance of nanotechnology, various nano-particles have shown promise as strong antimicrobial agents against a broad spectrum of microorganisms. These nanoparticles also have potential applications in medical devices, water treatments systems, environmental sensors and so on. However, with increasing concerns about the impact of engineered nanoparticles, many researchers are recently reporting the cytotoxicity of nanoparticles. In this review paper, we summarized the antimicrobial activities and mechanisms of various kinds of engineered nanoparticles to imprale understanding about these characteristics of nanoparticles.

• Journal of the Korean Chemical Society
• /
• v.61 no.4
• /
• pp.211-217
• /
• 2017

The purpose of this study was to examine UK students' use of multimodal representations in science. Students were asked to explain their understandings of the scientific concept and presentation of the multimodal representations in a science Assessing Pupils' Progress (APP) task. Participants of this study were fifty-four Year 7 students taught by the same teacher. Students from one class (27 students) were assigned to the experimental group, and then they received instruction encouraging the using of multimodal representations as evidences to support students' claims. One class (27 students) was assigned to the control group and they received instruction with traditional teaching methods. Both groups performed an APP task for assessment. The samples of APP assessments produced by students both from the experimental and control groups were analyzed using an analysis framework of multimodal representations, embeddedness in evidence and understanding of scientific concepts. Data analysis indicated that the students in the experimental group performed better than that of the control group on embeddedness of multimodal representations in the APP task. In addition, there was a significant difference between the two groups in the evaluation of understand of the scientific concepts.