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991.
Sung Cho Jong Min Lim Jung-Min You Seungwon Jeon Dongho Kim 《Israel journal of chemistry》2016,56(2-3):169-174
We investigated the electronic perturbation between graphene oxide and cobalt porphyrin to reveal the origin of the enhanced electrocatalytic activity of a hybrid complex using time-resolved spectroscopic measurements and theoretical calculations. The impulsively generated charge-separated state, GO−-(CoIIAPFP)+, undergoes fast charge recombination (<10 ps) between GO− and (CoIIAPFP)+ moieties. This fast charge recombination is directly related to the quick neutralization of (CoIIAPFP)+, which shortens the dead time of inactive CoIIIAPFP after the electrocatalytic reduction reaction. The fast transformation of inactive CoIIIAPFP to active CoIIAPFP is an important factor in the enhanced electrocatalytic activity of the hybrid complex. 相似文献
992.
993.
Hyunjin Lim Sooyoun Park Hyeonsik Cheong Hyun-Min Choi Young Chool Kim 《Diamond and Related Materials》2010,19(10):1254-1258
We have performed low-temperature (8 K) photoluminescence (PL) measurements on 71 natural and 12 high-pressure-and-high-temperature (HPHT)-treated type IIa diamonds. The GR1, NV0, NV?, H4, and H3 defect center PL signals are compared. Some distinct differences in the PL lineshape, intensity, and appearance of side-band PL signals are observed. Furthermore, we processed 6 of the natural diamond samples with the HPHT treatment to investigate the effect of the treatment on the PL spectrum. By systematically analyzing the differences in the PL spectra, we developed a scheme to discriminate natural and HPHT-treated diamonds with 99% validity. 相似文献
994.
Formation of the cone-shaped multi-walled carbon nanotube (MWCNT) bundles was investigated with the consideration of the induced dipole moments of the MWCNTs interaction under the ion irradiation which is accelerated by the applied sheath electric field for the various argon, hydrogen, nitrogen, and oxygen plasmas. Vertically grown MWCNTs were irradiated by energetic ion whose energy and dose were controlled by the sheath formed on the MWCNT substrate. Plasma irradiation was carried out in a downstream region separated from the plasma source region, providing that the irradiated ion density and energy could be controlled precisely with the sheath electric field. In argon and hydrogen plasmas, the cone-shaped MWCNT bundle was not fabricated, while it was formed successfully in nitrogen and oxygen plasmas. Especially, the oxygen plasma was the most effective in the formation of the bundle. The mechanism of the bundle formation could be explained by a model explaining the interaction between the induced dipole moment of the MWCNT and the sheath electric field. For the nitrogen and oxygen plasma irradiated MWCNT, the induced dipole moment could be enhanced by C-N and C-O bonds so the size of the bundle is proportional to the ion irradiation and the sheath electric field. 相似文献
995.
Jong Hun Lim Won Seob Song Sung Yul Woo Dong Hyun Lee 《Korean Journal of Chemical Engineering》2010,27(3):785-790
A new reaction model for dichloropropanol (DCP) synthesis from glycerol chlorination is proposed based on the models reported by Tesser et al. (2007) and Luo et al. (2009). Two reaction steps, glycerol to glycerol-1-acetate and α-MCP to 3-chloropropandiol-1-acetate, were defined as reversible reactions and other reaction steps were defined as irreversible processes. Using the experimental data reported by Luo et al. (2009), the values predicted in this study were compared with the previous model reported by Luo et al. (2009) using both the average absolute deviation (AAD) and root mean square deviation (RMSD). The AAD and RMSD of the new model were 31% and 33% lower than that of the existing one, respectively. Overall, the proposed model for glycerol chlorination is superior to the previous model. 相似文献
996.
Ki-Young Choi In-Tack Lim Kyu-Chul Lee Ki-Young Oh Moon-Jip Kim 《Journal of Inorganic and Organometallic Polymers and Materials》2012,22(1):295-300
The reaction of [Ni(L)]Cl2·2H2O (L = 3.14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,01.18,07.12]docosane) with trans-1,4-cyclohexanedicarboxylic acid (H2chdc) generates a 1D coordination and 2D hydrogen-bonded polymer {[Ni(L)(chdc)2]·2H2O}n (1). The polymer complex was characterized by X-ray crystallography, spectroscopy and magnetic susceptibility. Each nickel(II)
ion has a distorted octahedral coordination environment with the four secondary amines of the macrocycle in which two trans carboxylate anions of the chdc2− ligand have assembled around each nickel center. The electronic spectrum of 1 in the solid state exhibits a high-spin octahedral environment. The magnetic behavior of 1 reveals a weak intramolecular antiferromagnetic interaction with J values of −1.15(2) cm−1. 相似文献
997.
Yeonsil Moon Changmok Lim Yeahoon Kim Won-Jin Moon 《International journal of molecular sciences》2021,22(6)
The role of the blood–brain barrier (BBB) breakdown has been recognized as being important in Alzheimer’s disease pathogenesis. We aimed to evaluate whether regional BBB integrity differed according to sex and whether differences in BBB integrity changed as a consequence of aging or cognitive decline, using dynamic contrast-enhanced (DCE)-magnetic resonance imaging (MRI). In total, 75 participants with normal cognition (NC) or mild cognitive impairment (MCI) underwent cognitive assessments and MRI examination including DCE-MRI. Regional Ktrans was calculated in cortical regions and the Patlak permeability model was used to calculate BBB permeability (Ktrans, min−1). Females had a lower median Ktrans in the cingulate and occipital cortices. In the “older old” group, sex differences in Ktrans were only observed in the occipital cortex. In the MCI group, sex differences in Ktrans were only observed in the occipital cortex. Age was the only predictor of cognitive assessment scores in the male MCI group; however, educational years and Ktrans in the occipital cortex could predict cognitive scores in the female MCI group. Our study revealed that females may have better BBB integrity in cingulate and occipital cortices. We also found that sex-related differences in BBB integrity are attenuated with aging or cognitive decline. 相似文献
998.
999.
A series of polyesters with alkylated triazole heterocyclic rings at the branches were designed and synthesized via the polycondensation reaction. The synthesized polyesters were examined with various spectroscopic methods such as Fourier transform IR, 1H NMR and 13C NMR. The alkyl chain length at the branch was found to affect the thermal stability of the polyesters, which decreased with longer alkyl chain. These polyesters possessed an aggregation‐induced emission enhancement characteristic evidenced by the transformation of the clear solutions in tetrahydrofuran with weak greenish blue emission to cloudy solutions with enhanced blue emission when water was added to promote aggregation. Furthermore, enhancement in the photoluminescence intensity was observed when the polyesters underwent photocrosslinking upon UV irradiation and appeared as self‐assembled aggregates. The formation of aggregates in the water ? tetrahydrofuran solutions and after photocrosslinking was confirmed via TEM analysis. The SEM images showed that the photocrosslinked polyesters were highly porous which may enhance the π ? π stacking interaction that improved the photoluminescence intensity. © 2015 Society of Chemical Industry 相似文献
1000.
Organic batteries are attractive alternatives to conventional inorganic batteries because of their low cost, biodegradation, and renewability, and their consequent environmental friendliness. We investigated the influence of carbon conductors and electrolytes in organic batteries using dilithium terephthalate (Li2C8H4O4). The synthesized dilithium terephthalate has well-grown crystallinity and non-uniform shaped particles without impurities. The dilithium terephthalate-based battery shows good electrochemical properties with a LiTFSI/TEGDME electrolyte and graphene as the carbon conductor in an organic electrode. The results are ascribed to the high lithium transference number of LiTFSI/TEGDME and the high electrical conductivity of graphene. 相似文献