• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2409-2413
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• 2007

Time resolved phosphorescence of Dibromobenzophenone (DBBP) choleic acid crystal was observed at 4.2 K as functions of excitation energy and delay time. The experimental results reveal that the energy transfer efficiency is dependent on the excitation energy, i.e. the density of acceptors sites. As the excitation energy or delay time increases, the resonance phosphorescence does not broaden and shift gradually, rather a broad luminescence band develops about 290 cm?1 to lower energy of the resonance phosphorescence. The observation implies that energy transfer from high to low energy sites in this system is controlled by emission of phonons or vibrons. The data of time resolved experiments were analyzed in terms of a mechanism involving direct donor-acceptor excitation transport by exchange coupling. It was concluded that an isotropic twodimensional exchange interaction topology is consistent with energy transfer in this system.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2369-2376
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• 2007

N2O has been found from experimental and theoretical considerations to bind on-top to the Pd(110) surface in a tilted end-on fashion via its terminal N atom. We use a frontier orbital description of the bonding interactions in the Pd-N2O system to obtain molecular insight into the catalytic mechanism of the activation of N2O by the Pd(110) surface giving rise to the formation of N2 and O on the surface. For the tilted end-on N2O binding mode, the LUMO 3π of N2O has good overlap with the Pd dσ and dπ orbitals which can serve as the electron donors. The donor-acceptor orbital overlap is favorable for electron transfer from Pd to N2O and is expected to dominate the surface reaction pathway of N2O decomposition.

• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.885-889
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• 2012

In this study, amine and metal oxide additives were investigated to improve $CO_2$ adsorption capacity of activated carbons (ACs). The characteristics of surface modified ACs were studied by X-ray photoelectron spectroscopy (XPS), $N_2$ adsorption, X-ray diffraction (XRD), and BET. Amine surface treatment decreased specific surface area and pore volume of ACs, but increased alkalinity by the incorporated nitrogen functional groups. Adsorption capacities of amine functionalized ACs was larger than original ACs, because basic group which can react with $CO_2$ was grafted on the ACs surface. Presence of copper oxides on ACs also enhances the carbon dioxide adsorption. The copper oxides could increase the adsorption rate of carbon dioxides due to the acid-base interaction (or electron acceptor-donor interaction). It was found that copper oxide loading was a promising method to improve the $CO_2$ adsorption capacity of ACs.

• Journal of Microbiology and Biotechnology
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• v.29 no.2
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• pp.268-273
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• 2019

The specificity of a Bacillus licheniformis uridine diphosphate (UDP) glycosyltransferase, YjiC, was increased towards thymidine diphosphate (TDP)-sugar by site-directed mutagenesis. The Arg-282 of YjiC was identified and investigated by substituting with Trp. Conversion rate and kinetic parameters were compared between YjiC and its variants with several acceptor substrates such as 7-hydroxyflavone (7-HF), 4',7-dihydroxyisoflavone, 7,8-dihydroxyflavone and curcumin. Molecular docking of TDP-glucose and 7-HF with YjiC model showed pi-alkyl interaction with Arg-282 and His-14, and pi-pi interaction with $His^{14}$ and thymine ring. YjiC (H14A) variant lost its glucosylation activity with TDP-glucose validating significance of His-14 in binding of TDP-sugars.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.5
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• pp.19-30
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• 2016

We presented a hydrodynamic modeling necessary to accurately reproduce shock-induced detonation of pyrotechnic initiator. The methodology for such numerical prediction of shock propagation is quite straight forward if the models are properly implemented and solved in a well-formulated shock physics code. A series of SSGT(Small Scale Gap Test) and detailed hydrodynamic simulation are conducted to quantify the shock sensitivity of an acceptor that contains 97.5% RDX. A TBI(Through Bulkhead Initiator) system, consisting of a train configuration of Donor(HNS+HMX) - Bulkhead(STS) - Acceptor(RDX), were investigated to further validate the interaction between energetic and non-reactive materials for predicting the detonating response for successful operation of such small pyro device.

• Transactions on Electrical and Electronic Materials
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• v.15 no.5
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• pp.262-264
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• 2014

Pristine ZnO, 3 wt.% Ga-doped (3GZO) and 3 wt.% Ag-doped (3SZO) ZnO nanowires (NWs) were grown using the hot-walled pulse laser deposition (HW-PLD) technique. The doping of Ga and Ag in ZnO NWs was observed by analyzing the optical and chemical properties. We optimized the synthesis conditions, including processing temperature, time, gas flow, and distance between target and substrate for the growth of pristine and doped ZnO NWs. The diameter and length of pristine and doped ZnO NWs were controlled under 200 nm and several ${\mu}m$, respectively. Low temperature photoluminescence (PL) was performed to observe the optical property of doped NWs. We clearly observed the shift of the near band edge (NBE) emission by using low temperature PL. In the case of 3GZO and 3SZO NWs, the center photon energy of the NBE emissions shifted to low energy direction using the Burstein Moss effect. A strong donor-bound exciton peak was found in 3 GZO NWs, while an acceptor-bound exciton peak was found in 3SZO NWs. X-ray photoelectron spectroscopy (XPS) also indicated that the shift of binding energy was mainly attributed to the interaction between the metal ion and ZnO NWs.

• Bulletin of the Korean Chemical Society
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• v.29 no.2
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• pp.335-338
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• 2008

New efficient red emitter having short p?-conjugation length and asymmetric bulky structure, 2-(7-diphenylamino-benzo[1,2,5]thiadiazole-4-ylmethylene)-malononitrile, was synthesized and characterized. Using this material as a dopant, we fabricated electroluminescence device with a structure of ITO/DNTPD/NPD/BTZA (5 wt% in Alq3)/Alq3/LiF/Al. The device exhibited a high brightness of 761 cd/m2 at a driving voltage of 4.8 V, and current efficiency is 0.75 cd/A. The Commission International de IEclairage (CIE) coordinates of the EL device were found to be (0.62, 0.37) at 10 mA/cm2.

• Bulletin of the Korean Chemical Society
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• v.13 no.1
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• pp.75-79
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• 1992

Differences in chromatographic properties in RPLC of four brands of cyano bonded silica stationary phases are rationalized in terms of the type and relative strength of the solute-stationary phase interactions, which can be readily inferred from multiple linear regression analyses of retention data for a set of standard compounds on the stationary phases under study based on the linear solvation energy relationships (LSERs). Although four brands of cyano bonded columns studied (CPS-Hypersil, Ultrasphere cyano, Spherisorb-CN and ${\mu}$-Bondapak-CN) have similar bonding density and have been prepared from monofunctional cyanopropylsilane reagents, they possess quite different, relative hydrogen bonding (HB) donor and acceptor strengths. Comparison of the retention behavior on a cyano-bonded silica column with that on an ODS column shows that there are significant differences in the strength of HB interactions between the solute and the stationary phase on the two columns with different functionalities. Information on the differences in the interaction characteristics among brands of the cyano-bonded silica columns and between the ODS and cyano-bonded columns can be utilized to optimize the selectivity for a given separation on these columns.

• Bulletin of the Korean Chemical Society
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• v.19 no.10
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• pp.1105-1109
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• 1998

A chiral stationary phase derived from (S)-N-(3,5-dinitrobenzoyl)leucine N-phenyl N-alkyl amide (CSP 2) was applied in separating the two enantiomers of various π-basic aromatic derivatives of leucine N-propyl amide in order to evaluate π-basic aromatic groups as an effective derivatizing group for the resolution of a-amino acids. Subsequently N-(3,5-dimethoxybenzoyl) group was found to be very effective as a π-basic aromatic derivatizing group. Based on these results, N-(3,5-dimethoxybenzoyl) derivatives of various a-amino N-propyl amides, N,N-diethyl amides and esters were resolved on the CSP derived from (S)-N-(3,5-dinitrobenzoyl) leucine N-phenyl N-alkyl amide (CSP 2) and the resolution results were compared with those on the CSP derived from (S)-N-(3,5-dinitrobenzoyl)leucine N-alkyl amide (CSP 1). The enantioselectivities exerted by CSP 2 were much greater than those exerted by CSP 1. In addition, racemic N-(3,5-dimethoxybenzoyl)-a-mino N,Ndiethyl amides were resolved much better than the corresponding N-(3,5-dimethoxybenzoyl)-a-mino N-propyl amides and esters on both CSPs. Based on these results, a chiral recognition mechanism utilizing the π-π donor-acceptor interaction and the two hydrogen bondings between the CSP and the analyte was proposed.

• Applied Chemistry for Engineering
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• v.32 no.3
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• pp.348-356
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• 2021

The lignocellulose-based dried watermelon rind (WR) was modified with sulfuric acid, namely SWR for enhancement of methylene blue (MB) adsorption from the aqueous solution. According to FT-IR analysis, after the modification of WR with sulfuric acid, the functional groups of R-SO₃H, COOH and -OH groups was formated or enhanced on the surface of the WR. Moreover, the point of zero charge (pHpzc) was changed from 6.3 to 4.1 after modification, which widened the range for adsorbing of cationic dye MB. The adsorption process of MB onto the SWR was suitable for pseudo-2nd-order and Langmuir model and the maximum adsorption capacity of Langmuir was found to be 334.45 mg/g at pH 7. In adition, the adsorption process occurs through the electrostatic interaction, hydrogen bridge formation, electron donor-acceptor relationship, and 𝜋-𝜋 electron dispersing force between functional groups on the carbon surface with MB molecules. Depending on functional groups available on the SWR surface, the MB adsorption mechanism can occur in combination with various interactions.