• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.129-129
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• 2012

Covalently bonded halogen ligands possess unusual charge distributions, attracting both electrophilic and nucleophilic molecular ligands to form halogen bonds. In many biochemical systems, halogen bonds coexist with hydrogen bonds, being complementary to them due to their similar bond strength and dissimilardirectionality. In this study, we directly visualize the individual molecular configuration of chlorinated 1,5-dichloroanthraquinone and brominated 1,5-dibromoanthraquinone molecules on Au(111) using scanning tunneling microscopy. The precise arrangements of observed molecular structures were explained in the context of halogen and hydrogen bonds. We discuss the distances and the strengths of the observed halogen and hydrogen bonds, which are consistent with previous bulk data.

• 한국수소및신에너지학회논문집
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• 제12권3호
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• pp.231-238
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• 2001

Electrocatalytic activity of palladium for hydrogen oxidation and reduction was studied using AC impedance method. The system under study was arranged in electrolytic mode consisting of Pd electrode under study, Pt counter electrode and Nafion electrolyte between them. Two types of Pd electrodes were used - carbon-supported Pd (Pd/C) and Pd foil electrode. Pd/C anode contacting pure hydrogen showed a steady decrease of charge transfer resistance with the increase of anodic overpotential, which is an opposite trend to that found with Pd foil anode. But Pd foil cathode also exhibited a decrease of the resistance with the increase of cathodic overpotential. The relationship between imposition of overpotential and subsequent change of the charge transfer resistance is determined by the ratio of the rate of faradaic process to the rate of mass transportation; if mass transfer limitation holds, increase of overpotential accompanies the increase of charge transfer resistance. Regardless of the physical type of Pd electrode, the anode contacting hydrogen/oxygen gas mixture did not reveal any independent arc originated from local anodic oxygen reduction.

• 공업화학
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• 제33권3호
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• pp.322-327
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• 2022

Fucoidans were degraded by hydrogen peroxide under the electron beam (2.5 MeV) with various radiation doses (5 kGy, 10 kGy, 15 kGy, and 20 kGy) at room temperature. The degradation property was analyzed with a gel permeation chromatography (GPC-MALLS) method. An average molecular weight of fucoidan decreased from 99,956 at the irradiation dose of 0 kGy to 6,725 at the irradiation dose of 20 kGy. The solution viscosity of fucoidans showed a similar pattern to the molecular weight change. The number of chain breaks per molecule (N) increased with increasing the irradiation dose and concentration of hydrogen peroxide. The radiation yield of scission value markedly increased with increasing the irradiation dose up to 15 kGy. Also a 10% hydrogen peroxide concentration was more efficient than that of 5%. The structures of degraded fucoidan samples were studied with Fourier transform infrared spectroscopy (FT-IR). The results showed that the degradation process did not significantly change the chemical structure or the content of sulfate group. The sulfur content of each sample was determined with an Elemental Analyzer. With increasing the concentration of hydrogen peroxide, the ratios of sulfur/carbon, hydrogen/carbon, and nitrogen/carbon slightly decreased. The antioxidant activities of fucoidans were investigated based on hydroxyl radical scavenging activities. The ability of fucoidan to inhibit the hydroxyl radical scavenging activity was depended on its molecular weight.

• Bulletin of the Korean Chemical Society
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• 제32권11호
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• pp.4011-4015
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• 2011

We explored the interpretation of the well-accepted correlation between the apparent peak maximum position shift and extent of molecular interactions, like hydrogen bonding and dipole-dipole interactions, based on the overlapped multiple band model. The simulation of two overlapped Lorentzian bands was carried out to interpret how the maximum position of a composite peak relates to the relative contributions of two species representing the different levels of molecular interactions, i.e., free (or very weekly bound) vs. strongly bound. To demonstrate the validity of our interpretation of the origin of the peak position shift, the temperaturedependent IR spectra of ethylene glycol were also analyzed. It was found through the analysis of simulated and experimental spectra that the apparent peak shift in certain case can be safely interpreted as the measure of the strength of hydrogen bonding. The result of this study gives a new insight to interpret molecular interactions probed by vibrational spectroscopy.

• 한국미생물·생명공학회지
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• 제11권3호
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• pp.211-216
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• 1983

R. sphaeroides K- 7에 의한 수소생성과 질소고정효소(nitrogenase)와의 연관성을 조사한 결과 수소생성은 질소고정효소에 의해 이루어지는 것으로 나타났다. 또한 수소생성은 수소효소(hydrogenase)와 무관하며 박테리오클로로필의 농도와도 무관한 것으로 나타났다. 글루타민산이 in vivo에서 질소고정효소의 활성도를 조절하는데 중요한 역할을 할 수 있는 것으로 나타났으며 질소개스를 이용해 키운 세균을 글루타민산 존재하로 옮겼을때 보다 큰 정도의 수소생성능 및 질소고정효소 활성도가 나타났다.

• Composites Research
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• 제37권1호
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• pp.32-39
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• 2024

고체수소저장은 수소 기반 경제 발전과 에너지 저장 기술 혁신의 핵심 주제로 부각되고 있다. 이러한 저장 방식은 압축 및 액화수소 저장 등 기존 방식에 비해 안전성과 저장 및 운용 효율성 측면에서 우수한 특성을 보여주고 있다. 본 연구에서는 다양한 구조적 설계 요소 별로 나노튜브 표면에서의 고체수소저장 성능을 평가하고자 한다. 본 연구는 나노튜브의 저장 메커니즘을 밝히고자 분자 역학 시뮬레이션(MD)을 도입하여 수행되었다. 본 연구의 시뮬레이션에는 다양한 직경, 다중벽 구조(MWNT), 단일벽 구조(SWNT)의 탄소나노튜브(CNT) 및 붕소-질소 나노튜브(BNNT)가 도입되어 진행되었다. 방사형 밀도 함수(RDF)를 통해 다양한 조건에서 수소의 저장 및 효과적인 방출을 분석한 결과, 반경 감소와 이중벽 구조가 고체 수소 저장을 높이는 데 기여하는 것으로 나타났다. 또한, 붕소-질소 나노튜브의 수소 저장 용량은 탄소 나노튜브에 비해 낮게 측정되었지만, 유효 수소 저장 측면에서는 탄소 나노튜브를 훨씬 능가하는 것으로 나타났다.

• 한국수소및신에너지학회논문집
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• 제12권1호
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• pp.51-63
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• 2001

In this paper molecular dynamics simulations were employed to investigate the structural and dynamic properties of hydrogen ions impacted on the Ni (100) surface with the $45^{\circ}$ incident angle. The initial kinetic energies of the hydrogen ion range from 100 to 1,600 eV. Together with the trajectory visualization of hydrogen ions, we computed scattering and penetration yields, mean energies and angles, and probability and energy distributions as a function of longitudinal and azimuthal directions. In the case of lower energy scattering ions, the multiple collision effects were found to be important to the third layers or lower. For higher energy penetrating ions, compared with the normal incident angle, it was significant the effective channeling effects through the Ni layers and the angle dependencies were indicated both in the longitudinal and the azimuthal angle directions.

• International Journal of Safety
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• 제6권1호
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• pp.16-21
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• 2007

Carbon nanotubes hold much promise as future materials for safe storage of hydrogen. In this paper, hydrogen transport mechanisms in single-walled carbon nano-tubes (SWNTs) for various temperatures and chiral indices were studied using molecular dynamics simulation method. The SWNT models of zigzag (10,0), chiral (10,5) and armchair (10,10) with hydrogen molecules inside were simulated at temperatures ranging from 253K to 373K. Movements of hydrogen molecules ($H_2$) inside a SWNT were analyzed using mean-square displacements and velocity autocorrelation functions.

• BMB Reports
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• 제29권4호
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• pp.380-385
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• 1996

Ovomucoid third domain is a serine proteinase inhibitor protein which consists of 56 amino acid residues. A fifty picosecond molecular dynamics (MD) simulation was carried out for ovomucoid third domain protein with 5 $\AA$ layer of water molecules. A comparison of main chain atoms in the MD averaged structure with the crystal structure showed that most of the backbone structures are maintained during the simulation. Investigation of the intramolecular hydrogen bondings indicated that most of the interactions between main chain atoms were conserved, whereas those between side chains were reorganized for the period of the simulation. Especially, the side chain interactions around the scissile bond of reactive site P1 (Met18) were found to be more extensive for the MD structures. During the simulation, hydrogen bonds were maintained between the side chains of Glu19 and Arg21 as well as those of Thr17 and Glu19. Extensive side chain interactions observed in the MD structures may shed light on the question of why protein proteinase inhibitors are strong inhibitors for proteinases rather than good substrates.

• 한국자기공명학회논문지
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• 제22권4호
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• pp.139-143
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• 2018

Short antimicrobial peptide, A4W, have been studied by molecular dynamics (MD) simulation in an explicit dodecylphosphocholine (DPC) micelle. Peptide was aligned with DPC micelle and transferred new peptide-micelle coordinates within the same solvent box using specific micelle topology parameters. After initial energy minimization and equilibration, the conformation and orientation of the peptide were analyzed from trajectories obtained from the RMD (restrained molecular dynamics) or the subsequent free MD. Also, the information of solvation in the backbone and the side chain of the peptide, hydrogen bonding, and the properties of the dynamics were obtained. The results showed that the backbone residues of peptide are either solvated using water or in other case, they relate to hydrogen bonding. These properties could be a critical factor against the insertion mode of interaction. Most of the peptide-micelle interactions come from the hydrophobic interaction between the side chains of peptide and the structural interior of micelle system. The interaction of peptide-micelle, electrostatic potential and hydrogen bonding, between the terminal residues of peptide and the headgroups in micelle were observed. These interactions could be effect on the structure and flexibility of the peptide terminus.