• KSTLE International Journal
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• v.4 no.1
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• pp.14-17
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• 2003

The electrical and rheological properties of a chitosan malonate suspension in silicone oil was investigated by varying the electric fields, volume fractions of particles, and shear rates, respectively, The chitosan malonate susepnsion showed a typical electrorheological (ER) response caused by the polarizability of an amide polar group and shear yield stress due to the formation of multiple chains upon application of an electric field. The shear stress fur the suspension exhibited a linear dependence on the volume fraction and an electric field power of 1.88. On the basis of the experimental results, the newly synthesized chitosan malonate suspension was found to be an anhydrous ER fluid.

• Journal of the Korean Chemical Society
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• v.54 no.5
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• pp.650-652
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• 2010

• Bulletin of the Korean Chemical Society
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• v.33 no.6
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• pp.2051-2054
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• 2012

• Bulletin of the Korean Chemical Society
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• v.34 no.5
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• pp.1592-1594
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• 2013

• Proceedings of the Membrane Society of Korea Conference
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• 1998.10a
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• pp.37-38
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• 1998

물질을 분리하기 위해서는 두 물질간의 현저한 물리적 성질의 차가 있어야 한다. 일반적으로 막분리법을 이용하여 기체분리를 수행하느 경우에는 확산계수와 용해도 차이에 의한 투과선택도를 얻게 된다. 막분리를 위한 기체간의 물리적 성질로는 기체의 크기차이, 고분자에 대한 기체용해도 차이 등이 있다.(생략)

• Bulletin of the Korean Chemical Society
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• v.18 no.12
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• pp.1256-1260
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• 1997

A series of acyclic polyethers bearing amide end-groups and lipophilic alkyl chains (3-5) were successfully synthesized with quantitative yields. Based upon the transport experiment in a bulk liquid membrane (BLM) system and solvent extraction, a very high selectivity of Pb2+ over other transition metal cations was observed. Measurement of thermodynamic parameters for complexation in methanol at 25 ℃ gave a strong evidence for excellent selective complexation for lead ion over other transition metal ions.

• Bulletin of the Korean Chemical Society
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• v.12 no.6
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• pp.674-678
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• 1991

Methanolysis of a ${\beta}$-lactam ring of a cephalosporin was simulated with AM1 semiempirical quantum mechanical calculation. The tetrahedral intermediate TD1 from an O-protonated cephalosporin and a methanol transfers the proton intramolecularly to the C-4 carboxylate to generate an oxyanion, i.e., second tetrahedral intermediate TD2, which undergoes the amide bond cleavage without further protonation on the N-5. For this cleavage a low-energy barrier TS2 was located. According to the energy diagram, tetrahedral intermediates easily undergo ring cleavage even without the protonation on the amide nitrogen.

• Composites Research
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• v.14 no.4
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• pp.15-26
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• 2001

Interfacial properties and microfailure degradation mechanisms of the bioabsorbable composites fur implant materials were investigated using micromechanical technique and nondestructive acoustic emission (AE). As hydrolysis time increased, the tensile strength, the modulus and the elongation of poly(ester-amide) (PEA) and bioactive glass fibers decreased, whereas these of chitosan fiber almost did not change. Interfacial shear strength (IFSS) between bioactive glass fiber and poly-L-lactide (PLLA) was much higher than PEA or chitosan fiber/PLLA systems using dual matrix composite (DMC) specimen. The decreasing rate of IFSS was the fastest in bioactive glass fiber/PLLA composites whereas that of chitosan fiber/PLLA composites was the slowest. AE amplitude and AE energy of PEA fiber decreased gradually, and their distributions became narrower than those in the initial state with hydrolysis time. In case of bioactive glass fiber, AE amplitude and AE energy in tensile failure were much higher than in compression. In addition, AE parameters at the initial state were much higher than those after degradation under both tensile and compressive tests. In this work, interfacial properties and microfailure degradation mechanisms can be important factors to control bioabsorbable composite performance.

• The Korean Journal of Pesticide Science
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• v.18 no.4
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• pp.439-442
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• 2014

Cinnamyl derivatives are abundant secondary metabolite in biomass, and they have been studied on their biological activities. However, little information was available for plant growth regulation of the cinnamyl derivatives. In here, the acid, amide, alcohol, aldehyde and ester of cinnamyl derivatives were screened for their root growth inhibition properties including germination. The aldehyde, amide and ester derivatives showed better the root growth inhibition than the carboxylic acid, and the meta-positioned electron withdrawing group on cinnamyl derivatives enhanced the inhibition activity. 3-Chlorocinnamic acid, cinnamaimde and 4-methoxycinnamaldehyde were highlighted with the early stage root development inhibition ($GR_{50}$ < 100 mg/L) on Brassica campestris.

• The Korean Journal of Zoology
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• v.13 no.3
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• pp.75-84
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• 1970

Gamma-radiolyses of oxygenated and deoxygenated glycylglycylclycine in aqueous solution and in the solid state are observed, with special regards to peptied bond rupture for elucidation of radiolytic mechanism of proteins, by means of chromatorgraphic separation of degradation products, spectrophotometric quantitation of carbonyl compounds, micro-titration of amide formation, infrared spectrophptometry, and ultraviolet spectrophotometry for evaluation of radiation damage. Essential difference of peptide bond rupture is observed in solution and in the solid state, being high in the former and negligible in the latter. On the other hand, the presence of and obsence of oxygen in solution during irradiation are not so significant with respect to peptide bond rupture, except the recombination of free-radicals produced in deoxygenated solution. Peptide bond rupture in solution is attributable to the mechanisms proposed by Garrison et al.; dehydrogenation followed by hydrolysis to yield acid amide and carbonyl function as found on the basis of radiolytic products. Peptide bond attack at $\\alpha$-carbon locus might be suggestive for irradiated solid but not significant in view of low degree of peptide bond rupture.