• Mass Spectrometry Letters
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• 제12권4호
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• pp.131-136
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• 2021

Collision-induced dissociation of peptides involves a series of proton-transfer reactions in the activated peptide. To describe the kinetics of energy-variable dissociation, we considered the heat capacity of the peptide and the Marcus-theory-type proton-transfer rate. The peptide ion was activated to the high internal energy states by collision with a target gas in the collision cell. The mobile proton in the activated peptide then migrated from the most stable site to the amide oxygen and subsequently to the amide nitrogen (N-protonated) of the peptide bond to be broken. The N-protonated intermediate proceeded to the product-like complex that dissociated to products. Previous studies have suggested that the proton-transfer equilibria in the activated peptide affect the dissociation kinetics. To take the extent of collisional activation into account, we assumed a soft-sphere collision model, where the relative collision energy was fully available to the internal excitation of a collision complex. In addition, we employed a Marcus-theory-type rate equation to account for the proton-transfer equilibria. Herein, we present results from the integrated thermochemical approach using a tryptic peptide of ubiquitin.

• 터널과지하공간
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• 제10권2호
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• pp.218-226
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• 2000

고성능 폭약의 성능을 결정하기 위해서는 폭발압력, 폭발속도, 열, 발생되는 가스 등이 정확히 기술될 수 있어야 한다. 본 연구에서는 실측하는데 어려움이 따르는 폭굉 시의 현상을 이해하기 위해 폭약이 폭발할 때 발생하는 압력, 부피팽창, 온도, 폭발속도 등을 이론적으로 계산하고자 하였다. 본 연구를 통해 폭발 현상을 표현하기 위한 계산 프로그램이 개발되었으며 이 프로그램을 이용하여 ANFO와 NG에 대해 폭약성능에 영향을 미치는 요소들을 이론적으로 계산하였다.

• Mass Spectrometry Letters
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• 제12권4호
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• pp.126-130
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• 2021

The mass spectrometry (MS) provides the mass-to-charge ratios of atoms, molecules, stable/metastable complexes, and their fragments. I have taken a long journey with MS to address outstanding issues and problems by experiments and theory and gain insights into underlying principles in chemistry. By looking through the mass-to-charge ratio, I have studied thermochemical problems in silicon chemistry, the infrared multiphoton dissociation spectroscopy of organometallic intermediates, unimolecular dissociations of halotoluene radical cations, and the kinetics of association/dissociation of alkali halide triple ions with Lewis bases. Various MS platforms have been used to characterize non-covalent interactions between porphyrins and fullerenes and those between the group IIB ions and trioctylchalcogenides, and to examine the binding of the group IA, IIA and porphyrin ions to G-quadruplex DNA. Recently, I have focused on mass-balanced H/D isotope dipeptide tags for MS-based quantitative proteomics, a simple chemical modification method for MS-based lipase assay, and the kinetics and dynamics of energy-variable collision-induced dissociation of chemically modified peptides. Now, I see an important role of MS in global issues in the post-COVID era, as the society demands high standards for indoor air quality to contain the airborne-pathogen transmission as well as in-situ monitoring and tracking of carbon emissions to reduce global warming.