• Bulletin of the Korean Chemical Society
• /
• v.18 no.9
• /
• pp.916-922
• /
• 1997

A superconducting phase La2CuO4+δ (Tc=44 K) has been prepared by electrochemical oxidation which allows the oxygen to intercalat into the La2O2 layers. According to the Cu K-edge X-ray absorption near edge structure spectroscopic analysis, the oxidized phase shows an overall spectra shift of about 0.5 eV to a higher energy region compared to the as sintered one with the occurrence of an additional peak corresponding to the transition to the |1s13dn+1L-14pσ1 > final state, indicating the oxidation of CuO2 layer. From the X-ray photoelectron spectroscopic studies, it is found that the binding energy of La 3d5/2 is significantly shifted from 834.3 eV (as sintered La2CuO4) to 833.6 eV (as electrochemically oxidized La2CuO4+δ), implying that the covalency of the (La-O) bond is decreased due to the oxygen intercalation. The O 1s spectra do not provide an evidence of the superoxide or peroxide, but the oxide (O2-) with the contaminated carbonate (CO32-) based on the peaks at 529 eV and 532 eV, respectively, which is clearly confirmed by the Auger spectroscopic analysis. Oxygen contents determined by iodometric titration (δ=0.07) and thermogravimetry (δ=0.09) show good coincidence each other, also giving an evidence for the "O2-" nature of excess oxygen. From the above results, it is concluded that "O2-" appeared as O 1s peak at 528.6 eV is responsible for superconductivity of La2CuO4+δ.

• Bulletin of the Korean Chemical Society
• /
• v.21 no.6
• /
• pp.588-594
• /
• 2000

Structural changes of an iron phthalocyanine (FePC) monolayer induced by adsorption and externally applied potential on high area carbon surface have been investigated in situ by iron K-edge X-ray absorption fine structure (XAFS) in 0.5 M $H_2S0_4.$ Fine structures shown in the X-ray absorption near edge structure (XANES) for microcrystalline FePC decreased upon adsorption and further diminished under electrochemical conditions. Fe(II)PC(-2) showed a 1s ${\rightarrow}$ 4p transition as poorly resolved shoulder to the main absorption edge rather than a distinct peak and a weak 1s ${\rightarrow}$ 3d transition. The absorption edge position measured at half maximum was shifted from 7121.8 eV for Fe(lI)PC(-2) to 7124.8 eV for $[Fe(III)PC(-2)]^+$ as well as the 1s ${\rightarrow}$ 3d pre-edge peak being slightly enhanced. However, essentially no absorption edge shift was observed by the 1-electron reduction of Fe(Il)PC(-2), indicating that the species formed is $[Fe(II)PC(-3)]^-$. Structural parameters were obtained by analyzing extended X-ray absorption fine structure (EXAFS) oscillations with theoretical phases and amplitudes calculated from FEFF 6.01 using multiple-scattering theory. When applied to the powder FePC, the average iron-to-phthalocyanine nitrogen distance, d(Fe-$N_p$) and the coordination number were found to be 1.933 $\AA$ and 3.2, respectively, and these values are the same, within experimental error, as those reported ( $1.927\AA$ and 4). Virtually no structural changes were found upon adsorption except for the increased Debye-Wailer factor of $0.005\AA^2$ from $0.003\AA^2.$ Oxidation of Fe(II)PC(-2) to $[Fe(III)PC(-2)]^+$ yielded an increased d(Fe-Np) (1 $.98\AA)$ and Debye-Wailer factor $(0.005\AA^2).$ The formation of $[Fe(II)PC(-3)]^-$, however, produced a shorter d(Fe-$N_p$) of $1.91\AA$ the same as that of crystalline FePC within experimental error, and about the same DebyeWaller $factor(0.006\AA^2)$.

• Journal of Adhesion and Interface
• /
• v.13 no.4
• /
• pp.188-192
• /
• 2012

Herein, CdS-coated PMMA nanoparticles were prepared by in-situ surfactant-free emulsion copolymerization and subsequent CdS coating process. As-prepared CdS/PMMA hybrid particles had 201.7 nm in diameter. The amount of CdS nanocrystals in the hybrid particles was 10.37 wt% determined by TGA and elemental analysis. The size of CdS crystals was 3.55 nm preferentially grown in (111) plane. UV-vis spectrum of PMMA/CdS nanoparticles showed the significant blue-shift in optical illumination. The reason was found because the synthesized CdS nanocrystals on PMMA particles had a different band gap energy of 2.70 eV which was significantly higher than that of known-value of bulk CdS (2.41 eV) due to a quantum confinement effect.

• Journal of the Semiconductor & Display Technology
• /
• v.8 no.3
• /
• pp.19-23
• /
• 2009

We have studied dielectric characteristics of low-k interlayer dielectric materials was fabricated by plasma enhanced chemical vapor deposition (PECVD). BTMSM precursor was introduced with the flow rates from 24 sccm to 32 sccm by 2 sccm step in the constant flow rate of 60 sccm $O_2$. Then, SiOCH thin film deposited at room temperature was annealed at temperature of $400^{\circ}C$ and $500^{\circ}C$ for 30 minutes in vacuum. The vibrational groups of SiOCH thin films were analyzed by FT/IR absorption lines, and the dielectric constant of the low-k SiOCH thin films were obtained by measuring C-V characteristic curves. With the result that FTIR analysis, as BTMSM flow rate increase, relative carbon content of SiOCH thin film increased from 29.5% to 32.2%, and increased by 32.8% in 26 sccm specimen after $500^{\circ}C$ annealing. Dielectric constant was lowest by 2.32 in 26 sccm specimen, and decreased more by 2.05 after $500^{\circ}C$ annealing. Also, leakage current is lowest by $8.7{\times}10^{-9}A/cm^2$ in this specimen. In the result, shift phenomenon of chemical bond appeared in SiOCH thin film that BTMSM flow rate is deposited by 26 sccms, and relative carbon content was highest in this specimen and dielectric constant also was lowest value

• The Journal of the Korea institute of electronic communication sciences
• /
• v.18 no.2
• /
• pp.277-284
• /
• 2023

It is not easy to implement an energy management system in an industrial complex where small businesses are scattered, so the method of collecting and adjusting energy-related data is mainly used. FEMS is a system that responds to the demand for a paradigm shift from a passive energy management method to an active energy management method using IoT and ICT. In this study, a factory energy management system(FEMS) is designed for small and medium-sized enterprises located in chemical industrial complexes. Efficiency was confirmed by reviewing energy saving measures and efficiencies through FEMS for the electric energy of facilities built in each company. The cost effectiveness of FEMS is created when it is utilized by responsible and empowered personnel within the business processes of the host company. Therefore, it is necessary to utilize EMS that can be applied to the planning, support, operation and evaluation, and continuous improvement of the energy management system to achieve corporate organization and energy management goals.

• Analytical Science and Technology
• /
• v.13 no.4
• /
• pp.494-503
• /
• 2000

A 21-residue peptide corresponding to amino acids 84-104 of $p16^{INK4A}$, the tumor suppressor, has been synthesized and its structure was studied by Circular Dichroism, $^1H$ NMR spectroscopy and molecular modeling. A p16-derived peptide (84-104 amino acids) forming stable complex with CDK4 and CDK6 inhibits the ability of CDK4/6 to phosphorylate pRb in vitro, and blocks cell-cycle progression through G1/S phase as shown in the function of the full-length p16. Its NMR spectral data including NOEs, $^3J_{NH-H{\alpha}}$ coupling constants, $C_{\alpha}H$ chemical shift, the average amplitude of amide chemical shift oscillation and temperature coefficients indicate that the secondary structure of a p16-derived peptide is similar to that of the same region of full-length p16, which consists of helix-turn-helix structure. The 3-D distance geometry structure based on NOE-hased distance and torsion angle restraints is characterized by ${\gamma}$-turn conformation between residues $Gly^{89}-Leu^{91}$(${\varphi}_{i+1}=-79.8^{\circ}$, ${\varphi}_{i+1}=60.2^{\circ}$) as evidenced in a single crystal structure for the corresponding region of p18 or p19, but is undefined at both the N and C termini. This compact and rigid ${\gamma}$-turn region is considered to stabilize the structure of p16-derived peptide and serve as a site recognizing cyelin dependent kinase, and this well-defined ${\gamma}$-turn structure could be utilized for the design of anti-cancer drug candidates.

• Natural Product Sciences
• /
• v.6 no.4
• /
• pp.193-198
• /
• 2000

Phytochemical study of the constitutive polyphenolics of the flower aqueous alcohol extract of Tamarix tetragyna was carried out. The new sulphated flavonol, quercetin 3',4'-dimethyl ether $3-O-KSO_3$ as well as the new natural galloyl glucose, $2-O-galloyl-({\alpha}/{\beta})-^4C_1-glucopyranose$ were isolated and characterized. The known sulphated flavonols, kaempferol 7,4-dimethyl ether $3,5-di-O-KSO_3$, quercetin 7-methyl ether $3,3',4'-tri-O-KSO_3$, quercetin 7,4'-dimethyl ether $3-O-KSO_3$ and quercetin $3-O-KSO_3$ and the known sulphated phenolics, isoferulic acid $3-O-KSO_3$ and ellagic acid 4,4'-dimethyl ether $3-O-KSO_3$ were also separated and identified. The structures were established by conventional methods of analysis and confirmed by $^1H-,\;^{13}C-NMR$ and negative ESI-mass spectrometry. 2D-homonuclear chemical shift correlation NMR experiment was applied for the new natural galloylglucose.

• Molecules and Cells
• /
• v.24 no.3
• /
• pp.437-440
• /
• 2007

$OGL-20P^T$-358 is a novel 66 amino acid residue protein from the hyperthermophile Thermococcus thioreducens sp. nov., strain $OGL-20P^T$, which was collected from the wall of the hydrothermal black smoker in the Rainbow Vent along the mid-Atlantic ridge. This protein, which has no detectable sequence homology with proteins or domains of known function, has a calculated pI of 4.76 and a molecular mass of 8.2 kDa. We report here the backbone $^1H$, $^{15}N$, and $^{13}C$ resonance assignments of $OGL-20P^T$-358. Assignments are 97.5% (316/324) complete. Chemical shift index was used to determine the secondary structure of the protein, which appears to consist of primarily ${\alpha}$-helical regions. This work is the foundation for future studies to determine the three-dimensional solution structure of the protein.

• Journal of Magnetics
• /
• v.19 no.1
• /
• pp.68-71
• /
• 2014

Copper doped Zinc Oxide nanofilms were prepared using a simple and low cost wet chemical method. The microstructures, phase structure, Raman shift and optical absorption spectrum as well as magnetization were investigated for the nanofilms. Room temperature ferromagnetism has been observed for the nanofilms. Structural analyses indicated that the films possess wurtzite structure and there are no segregated clusters of impurity phase appreciating. The results show that the ferromagnetism in Copper doped Zinc Oxide nanofilms is driven either by a carrier or defect-mediated mechanism. The present work provides an evidence for the origin of ferromagnetism on Copper doped Zinc Oxide nanofilms.

• Elastomers and Composites
• /
• v.52 no.4
• /
• pp.237-241
• /
• 2017

The tensile strength (TS) and elongation-at-break (EB) loss of a CR/CB rubber composite sample prepared for the automotive parts were measured after accelerated thermal ageing at temperatures of 100, 120, 140, and $150^{\circ}C$. The change in TS was observed to be linear from the master curve prepared using the time-temperature superposition-principle (TTSP). An Arrhenius type of shift factor, $a_T$ was used to predict the life time of the sample, and a plot of ln $a_T$ vs. 1/T was also shown to be linear. The activation energy ($E_a$) of the sample was calculated as 70.30 kJ/mole from the Arrhenius plot. The expected life time of the sample was predicted at the given operating conditions by applying Arrhenius analysis. Assuming the $E_a$ value was constant at lower operating condition, life time of the sample was calculated as 2.3 years when the life limit was set as time to reach the 20% decrease of the initial TS value at operating temperature of $40^{\circ}C$.