• Bulletin of the Korean Chemical Society
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• v.12 no.6
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• pp.625-628
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• 1991

Using uniform flat plate-like samples of ZSM-5 zeolites, diffusion coefficients were measured volumetrically for the diffusion of xylene, ethyltoluene and diethylbenzene by direct measurement of sorption rate. Toluene disproportionation over H(100)-, K(72)-and Cs(82)-ZSM-5 at 773 K and toluene methylation, toluene ethylation and ethylbenzene ethylation over Cs(75)-ZSM-5 at 623 K were carried out. The selective formation of para xylene during the toluene disproportionation, presumably due to the increased tortuosity over Cs-ZSM-5, could be explained by smaller diffusion coefficient in Cs-ZSM-5 than in K-and H-ZSM-5. The para selectivity increased in the order; toluene methylation < toluene ethylation < ethylbenzene ethylation. As the chain length of the alkyl substituent in dialkylbenzenes is increased, the para selectivity of the products was improved. It may be attributed to the differences in the ratios of diffusion coefficient of para products to that of ortho ones. Diffusion coefficient of m-xylene was about 1 order of magnitude smaller than that of o-xylene.

• Journal of the Korean Chemical Society
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• v.59 no.2
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• pp.142-147
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• 2015

Two new chitosan derivatives, polyamine grafted chitosan copolymers have been synthesized for corrosion protection of carbon steel in acidic medium. First, methyl acrylate graft chitosan copolymer (CS-MAA) was prepared by the reaction of chitosan (CS) and methyl acrylate (MAA) via the Michael addition reaction. Then, CS-MAA was reacted with ethylene diamine (EN) and triethylene tetramine (TN) respectively to synthesize ethylene diamine grafted chitosan copolymer (CS-MAA-EN) and triethylene tetramine grafted chitosan copolymer (CS-MAA-TN), and the structures were characterized by Fourier-transform infrared spectroscopy (FT-IR). At last, the corrosion inhibition activities on Q235 carbon steel were investigated by using gravimetric measurements, metallographic microscope, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The compounds CS-MAA-EN and CS-MAA-TN show an appreciable corrosion inhibition property against corrosion of Q235 carbon steel in 5% HCl solution at $25^{\circ}C$. It has been observed that CS-MAA-EN shows greater corrosion inhibition efficiency than CS-MAA-TN. The inhibition efficiency of CS-MAA-EN was close to 90% when the mass fraction concentration was 0.2%~0.3%; the inhibition efficiency of CS-MAA-TN was close to 85% when the mass fraction concentration was 0.02%. The present work provided very promising results in the preparation of green corrosion inhibitors.

• Bulletin of the Korean Chemical Society
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• v.27 no.6
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• pp.853-856
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• 2006

Dion-Jacobson phases $CsCa_2Nb_2FeO_9$ and $CsCa_2Nb_2AlO_9$ were reinvestigated by the Rietveld analysis of powder X-ray diffraction (XRD) method, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). These nominal compounds, previously known as the oxygen-deficient layered perovskites with the sequences of $NbO_6-MO_4-NbO_6$ in tripled slab, in fact, were mixed phases of n = 3 Dion-Jacobson phases and impurities such as $Ca_2NbFeO_6$ and $Ca_3Al_2O_6$. The difference of morphology and chemical in-homogeneity between Dion-Jacobson phases and impurities could be clearly identified by scanning electron microscopy with energy-dispersive X-ray spectroscopy. The chemical composition of $CsCa_2Nb_2FeO_9$ was calculated into $Cs_{0.59}Ca_{2.64}Nb_{2.92}Fe_{0.81}$ in small agglomerate crystals and $Cs_{0.95}Ca_{1.97}Nb_{3.08}Fe_{0.15}$ in long plate-like crystals.

• Journal of the Korean Chemical Society
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• v.24 no.1
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• pp.1-7
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• 1980

Solvolysis rate constants for methylchloroformate, methylthionochloroformate, methylthiolchloroformate and methyldithiochloroformate have been determined conductometrically in methanol, ethanol and ethanol-water mixtures and activation parameters have been derived. Results show that methylchloroformate solvolyzes through $S_N2$ process while methyldithiochloroformate solvolyzes by $S_N1$ process in all the solvent systems. The rate of hydrolysis decreased in the order, $CH_3S(CS)Cl>CH_3S(CO)Cl>CH_3O(CS)Cl>CH_3O(CO)Cl$ which corresponds to the order of decreasing $S_N1$ character. In methanol, $CH_3S(CS)Cl$ solvolyzed via the $S_N1$ mechanism while the others solvolyzed via the $S_N2$ process. In ethanol, however, $S_N2$ character was dominant for all the compounds, except methyldithiochloroformate, for which $S_N1$ character was still strong enough to accelerate the rate of ethanolysis. In ethanol-water mixtures, $CH_3S(CS)Cl$ and $CH_3S(CS)Cl$ solvolyzed via $S_N2$ process in ethanol-rich region while the $S_N1$ character increased greatly in water-rich region for the solvolysis of these compounds. The order of $S_N1$ character for solvolysis in water-rich region was the same as the order of hydrolysis rate.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.4
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• pp.533-537
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• 2004

The experiment was conducted to test the hypothesis that supplementing diets of lactating first parity sows with a mixture of carbohydrases (CS) improves lactation performance and second parity reproductive performance. The CS used in this study contained 7 units/g of $\alpha$-1,6-galactosidase, 22 units/g of $\beta$-1,4-mannanase, $\beta$-1,4-mannosidase and trace amounts of other enzymes. Twenty primiparous sows (Newsham Hybrid) were allotted to either the control group (no CS supplement) or the CS group (0.1% CS supplement) and fed the experimental diets during 21 d lactation period. Sows and nursing pigs were weighed at birth and weekly until weaning. Days of weaning-to-estrus were recorded. Sows had free access to feed and water. Feed intake of sows was measured daily. During the second parity gestation and lactation, all the sows were fed the same gestation and lactation diets and their reproductive performance was measured. During the second parity, there were 14 sows (7 sows per group) remained productive. For the first lactation, maternal body weight loss of the CS group was smaller (p<0.05) than that of the control group. There was no difference in litter weight gain between two groups. Voluntary feed intake of sows did not differ between the two groups. Days of weaning-to-estrus of the CS group were smaller (p<0.05) than those of the control group. In the second parity, there was no difference in the reproductive performance between the two groups. In conclusion, supplementing CS in the diet of lactating sows during the first parity decreased body weight loss and days of weaning-to-estrus of sows. However, these effects of the CS supplementation in the first parity were not successfully carried over to the second parity.

• Analytical Science and Technology
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• v.9 no.1
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• pp.43-51
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• 1996

We have discussed on the deintercalation process of Li-EaGICs and Li-EGICs synthesized under pressure and temperature by spontaneous oxidation reaction of those compounds based on the results of X-ray diffraction, thermal analysis and electrical specific resistivity analysis. According to the results of the X-ray analysis for the intercalation process, we have found that the stage 1 for Li-EaGICs and Li-EGICs were not completly formed, but their lower stages were formed mainly. And from this results of the deintercalation process, we have found that the deintercalation process did not occur any more after 4 weeks, and the Li-EGDICs have more residual lithium metals than LiEaGDICs between the graphite interlayers. According to the thermal decomposition analysis, Li-two compounds had included very hard exothermic reaction. And we have found that these compounds did not occrurred deintercalation reaction above $400^{\circ}C$. According to the results of the electrical specific resistivity measurements, Li-EGDICs have relatively lower electrical specific resistivity than Li-EaGDICs, and Li-EaGDICs showed a formation of the ideal curve. From these results, we can suggest that Li-EaGDICs have a better properties as an anode material secondary than Li-EGICs.

• Bulletin of the Korean Chemical Society
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• v.34 no.3
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• pp.731-734
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• 2013

Reduced tungsten bronze nanoparticles of ternary and quaternary compounds were prepared by adding sodium and cesium to crystal structures of tungsten trioxides ($Na_xCs_{0.33-x}WO_3$, x = 0, 0.11) while maintaining the overall alkali metal fraction at 0.33, in an attempt to control near infrared (NIR) shielding property in the particular wavelength range of 780 to 1200 nm. The structure and composition analysis of the quaternary compound, $Na_{0.11}Cs_{0.22}WO_3$, revealed that 93.1% of the hexagonal phase was formed, suggesting that both alkali metals were mainly inserted in hexagonal channel. The NIR shielding property for $Na_{0.11}Cs_{0.22}WO_3$ was remarkable, as this material demonstrated efficient transmittance of visible light up to 780 nm and enhancement in NIR shielding because of the blue-shifted absorption maximum in comparison to $Cs_{0.33}WO_3$.

• Journal of the Korean Magnetics Society
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• v.25 no.5
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• pp.139-143
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• 2015

The surface magnetism of the CsCl structured Co binary compounds, CoX (X = Ti, V, Nb) (001) surface was studied with the calculated electronic structure data obtained by the full-potential linearized augmented plane-wave (FLAPW) method. The magnetic moment of the surface Co atom of the Co-terminated CoTi(001) system was $1.19{\mu}_B$, which is enhanced compared with that of the Co atom in the center layer. The magnetic moment of the surface V atom in the V terminated the CoV(001) system was $1.64{\mu}_B$, which is more than twice of the center layered V atom. The magnetic moment of surface Co atom in the Co terminated CoV(001) system has the value of $1.34{\mu}_B$, little bit smaller than the bulk value. The magnetism was disappeared in the Co terminated CoNb(001) system, and the magnetic moment of the surface Nb atom in the Nb terminated CoNb(001) system was $0.26{\mu}_B$ which is little bit decreased compared to the center layer value.

• The Korean Journal of Mycology
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• v.40 no.1
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• pp.69-71
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• 2012

During search for novel bioactive materials from natural resources with the potential as health food and alternative medicine, the culture broth of Cordyceps longissima (CL) J106, J144 and C. scarabaeicola (CS) J94, J123 were prepared, and their effect on cytotoxicity and nitric oxide (NO) production in RAW 264.7 cells were investigated. Whereas the culture broth of CL J144 and CS J123 had cytotoxicity in RAW 264.7 cells, that of CL J106 and CS J94 did not. The culture broth of CL J106 and CS J94 suppressed NO production in RAW 264.7 cells activated with lipopolysaccharide (LPS) at a dose-dependent manner. These results suggest that culture broth, a by-product of Cordyceps, may have active compounds with anti-inflammatory effect. In addition, it appears that their biological activity is dependent on the strains in spite of the same species.

• Analytical Science and Technology
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• v.13 no.5
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• pp.565-572
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• 2000

In this paper it was described on the standards for Xe analysis by Wavelength Dispersive X-ray Spectrometer (WDS) of Electron Probe Micro Analyser. According to the experimental results, CsI and $BaCO_3$ are appropriate compounds as standard specimen for Cs, I and Ba which has not suitable pure metal standards. In the beam current of 10-30 nA range, the Cs x-ray intensity measured from CsBr and CsI was proportional to the beam current. It was found that the linear regression factor R, showing the linearity between the atomic number and x-ray intensity between In and Nd elements, was higher than 0.99 at 25 kV and PET crystal. The caJlculated x-ray intensity of Xe standard from this linear regression equation was 1.095 times higher than that ofTe at 25 kV.