• Mass Spectrometry Letters
• /
• v.15 no.1
• /
• pp.49-53
• /
• 2024

Ceramide is a lipid in which sphingoid bases and fatty acids are linked by amide bonds. As a marker of skin disease in the human stratum corneum, its disease-causing and therapeutic effects have been partially confirmed, and it is therefore an important element in commercially available cosmetic formulations. However, structural diversity caused by differences in the chain length, number, and location of hydroxyl groups makes quality control difficult. In this study, a method was established to separate different ceramide species using reversed-phase LC-MS/MS and thus enable qualitative evaluation. Separation of four standards was achieved within a short retention time, and the accuracy and sensitivity of the method were demonstrated by the low limit of detection (LOD) calculated based on the calibration curve showing linearity, with R² > 0.994. After verification of reproducibility and reliability through intra- and inter-day analyses, the efficiency of the method was confirmed through analysis of commercial cosmetic raw materials.

• Bulletin of the Korean Chemical Society
• /
• v.29 no.8
• /
• pp.1575-1578
• /
• 2008

• Proceedings of the Korean Magnetic Resonance Society Conference
• /
• 2002.01a
• /
• pp.6-6
• /
• 2002

• Bulletin of the Korean Chemical Society
• /
• v.32 no.4
• /
• pp.1346-1348
• /
• 2011

• Applied Microscopy
• /
• v.38 no.4
• /
• pp.383-386
• /
• 2008

In performing in situ heating transmission electron microscopy (TEM) for materials characterizations, arising concerns such as specimen drifts and unintentional Cu contamination are discussed. In particular, we analysed the thermal and mechanical characteristics of in situ heating holders to estimate thermal drift phenomena. From the experimental results, we suggest an empirical model to describe the thermal drift behavior so that we can design an effective plan for in situ heating experiment. Practical approaches to minimize several hindrances arisen from the experiment are proposed. We believe that our experimental recommendations will be useful for a microscopist fascinated with the powerful potential of in situ heating TEM.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.1
• /
• pp.209-212
• /
• 2010

• Bulletin of the Korean Chemical Society
• /
• v.28 no.3
• /
• pp.391-396
• /
• 2007

The three-dimensional structure of an inorganic crystal, CaMoO4 (space group I 41/a, a = 5.198(69) A and c = 11.458(41) A), was determined by electron crystallography utilizing a high voltage electron microscope. An initial structure of CaMoO4 was determined with 3-D electron diffraction patterns. This structure was refined by crystallographic image processing of high resolution TEM images. X-ray crystallography of the same material was performed to evaluate the accuracy of the TEM structure determination. The cell parameters of CaMoO4 determined by electron crystallography coincide with the X-ray crystallography result to within 0.033-0.040 A, while the atomic coordinates were determined to within 0.072 A.

• Mass Spectrometry Letters
• /
• v.11 no.4
• /
• pp.77-81
• /
• 2020

Characterization of the various chemical aspects of composite polymers is important for quality control of manufactured polymers. In this study, we compared three suitable matrices (α cyano-4-hydroxycinnamic acid [CHCA], 2,5 dihydroxy benzoic acid [2,5-DHB], and dithranol), to characterize various synthetic polymers by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Although the spectra obtained with the CHCA and 2,5-DHB matrices were generally good, in certain samples ghost peaks disappeared only when dithranol was used as the matrix. Furthermore, we examined the use of sodium trifluoroacetate (NaTFA) as an additive to reduce interference by metals and copolymers in the spectra. In conclusion, appropriate selection of a matrix, according to the characteristics of the polymer, and the use of additives to improve sensitivity are important considerations for polymer analysis and development.

• 나누는사람들
• /
• s.39
• /
• pp.22-23
• /
• 2007

KBSi 지원을 받아 이식치료를 받은 후 건강하게 지내고 있는 김남훈 군을 만나봤습니다.

• Publications of The Korean Astronomical Society
• /
• v.22 no.3
• /
• pp.55-61
• /
• 2007

The KASINICS (Korea Astronomy and Space science Institute Near Infrared Camera System) is a ground-based near-infrared (NIR) imaging instrument. KASINICS has offner relay optics to reduce unwanted infrared light. For the offner optics, we adopted an ultra precision machining process which is installed at KBSI (Korea Basics Science research Institute). Since the offner relay optics is made of aluminum 6061 metal material, we did several tests to reach the specification. We found that a 0.497mm radius nose bite and 220m/min machining speed are best tool and condition to make this offner optics with the precision machine. In this paper, we report the technical method of ultra precision machining and results of the KASINICS offner optics.