• Applied Biological Chemistry
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• v.45 no.4
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• pp.223-227
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• 2002

Characteristic stereostructures of farnesyl protein transferase (FPTase) inhibition materials isolated from Artemisia sylvatica and regioselectivity of biogenic Diels-Alder reactions between dehydromatricarin molecules A and B were examined quantitatively. Results revealed that the major reaction of frontier molecular orbital (FMO) interaction proceeds through charge-control reaction between LUMO of A16, dienophile and HOMO of B1, diene, and the isolated 8-acetylarteminolide and artanomaloide were minor products. FPTase inhibition activity and hydrophobicity of 8-acetylarteminolide were $pI_{50}=3.75$ and logP=2.62, respectively. FPTase inhibition activity of 8-acetylarteminolide was higher than those of artanomaloide and dehydromatricarin.

• Archives of Pharmacal Research
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• v.12 no.2
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• pp.88-93
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• 1989

In order to obtain some informations about the effect of molecular weight on the release rate of drug from drug carrier, two types of poly-L-glutamic acid (PLGA)-cytarabine (ara-C) conjugates, PLGA-ara-C:I and PLGA-ara-C:II, were synthesized using two types of PLGA having different average molecular weight, 43,000 and 77,800, respectively. The PLGA-ara-C conjugates were synthesized by mixed anhydride method and found to be covalently linked. Both types of conjugates charged negatively at biological pH. The pH-dependent release rate of ara-C was observed in both cases, and the release rate was accelerated in basic, acidic conditions (the k values were 0.015 $day^{-1}$ at pH 7.0, 0.024 $day^{-1}$ at pH 5.0, and 0.059 $day^{-1}$ at pH 9.0 in the case of PLGA-ara-C:I) and in the presence of pretense. The time required for the release of 16.5% of ara-C from PLGA-ara-C:I were 8 hr and 144 hr in the presence and absence of protease, respectively. Although both types of conjugates showed similar drug substitution ratio, they showed different release rates. Between the two types of conjugates, PLGA-ara-C:II showed the faster release rate (0.030 vs 0.042 $day^{-1}$ in pH 7.4 phosphate buffer solution at $37^{\circ}C$) and the smaller activation energy for the release of drug (12.5 vs 7.7 Kcal/mol) than PLGA-ara-C:I. The characteristic effect of molecular weight on the release rates of PLGA-ara-C conjugates suggests that the drug release rate might be effectively controlled over a prolonged period of time by the combined use of the different types of PLGA-ara-C conjugates having different molecular weights.

• Journal of the Korean Ceramic Society
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• v.32 no.11
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• pp.1262-1268
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• 1995

Photoelectrochemical properties of p-GaAs electrode have been investigated. I-V characteristic shows that the cathodic photocurrent is observed at -0.7 V vs. SCE. The photoresponse at near 870~880nm wavelength indicates that the photogenerated carriers contibuted to the observed current. The maximum converson efficiency of 35% is obtained for a Xe lamp light source at 400nm. In C-V relation, capacitance peaks appeared at the frequencies of 100Hz and 300Hz due to the activation of the interfacial states which exist at the energy level corresponding to the one-third of the GaAs band gap. The difference of about 1.1V between flatband potential (Vfb) from the Mott-Schottky method and onset voltage from I-V curve is observed due to the trap of carriers at the interfacial states in the boundary between GaAs and electrolyte. In case of WO3 deposited p-GaAs electrode, higher positive onset current and photocurent density are obtained. This can be explained by the fact that carriers are generated by light penetrated into the WO3 thin flm as well as p-GaAs substrate and then move into the electrolyte effectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.6
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• pp.575-579
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• 2008

Al-doped p-type ZnO films were fabricated on n-Si (100) and homo-buffer layers in pure oxygen at $450^{\circ}C$ of by RF magnetron sputtering. Target was ZnO ceramic mixed with 2 wt% $Al_2O_3$. XRD spectra show that the Al-doped ZnO thin films have ZnO crystal structure and homo-buffer layers are beneficial to Al-doped ZnO films to grow along c-axis. Hall Effect experiments with Van der Pauw configuration show that p-type carrier concentrations are ranged from $1.66{\times}10^{16}$ to $4.04{\times}10^{18}\;cm^{-3}$, mobilities from 0.194 to $2.3\;cm^2V^{-1}s^{-1}$ and resistivities from 7.97 to $18.4\;{\Omega}cm$. p-type sample has density of $5.40\;cm^{-3}$ which is smaller than theoretically calculated value of $5.67\;cm^{-3}$. XPS spectra show that Ols has O-O and Zn-O structures and Al2p has only Al-O structure. P-ZnO:Al/n-ZnO:Al junctions were fabricated by magnetron sputtering. V-I curves show that the p-n junctions have rectifying characteristics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.408-409
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• 2007

Al-doped p-type ZnO films were fabricated on n-Si (100) and homo-buffer layers in pure oxygen at $450^{\circ}C$ by RF magnetron sputtering. Target was ZnO ceramic mixed with 2wt% $Al_2O_3$. XRD spectra show that the Al-doped ZnO thin films have ZnO crystal structure and homo-buffer layers are beneficial to Al-doped ZnO films to grow along c-axis. Hall Effect experiments with Van der Pauw configuration show that p-type carrier concentrations are ranged from $1.66{\times}10^{16}\;to\;4.04{\times}10^{18}cm^{-3}$, mobilities from 0.194 to $2.3cm^2V^{-1}s^{-1}$ and resistivities from 7.97 to $18.4{\Omega}cm$. P-type sample has density of $5.40cm^{-3}$ which is smaller than theoretically calculated value of $5.67cm^{-3}$. XPS spectra show that O1s has O-O and Zn-O structures and A12p has only Al-O structure. P-ZnO:Al/n-ZnO:Al junctions were fabricated by magnetron sputtering. V-I curves show that the p-n junctions have rectifying characteristics.

• Journal of the Korean Institute of Telematics and Electronics
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• v.20 no.1
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• pp.45-49
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• 1983

The four-layered(metal/insulator/n epi-layer/p+) controlled inversion devices have been fabricated. The I-V curve showed two characteristic states―an On state and an OFF state which were separated by a negative resistance region. The switching voltage and the holding voltage were about 5.0V and 2.5V, respectively. The switching voltage of the device was decreased by photo illumination while the holding voltage remained unaffected.

• Journal of Microbiology and Biotechnology
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• v.17 no.6
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• pp.919-927
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• 2007

Antagonistic fluorescent pseudomonads isolated from rhizospheric soil of rice were characterized by 16S rRNA amplicon and fatty acid methyl ester (FAME) analyses. Antagonistic isolates were grown in the fermentation media, and production of antibiotics was confirmed by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). Production of fungal cell-wall-degrading enzymes such as protease, cellulase, pectinase, and chitinase was determined. Dendrogram based on the major and differentiating fatty acids resulted into 5 clusters, viz., cluster I (P. pseudoalcaligenes group), cluster II (P. plecoglossicida group), cluster III (P. fluorescens group), cluster IV (P. aeruginosa group), and cluster V (P. putida group). Characteristic presence of high relative proportions of cyclopropane (17:0 CYCLO w7c) was observed in antagonistic bacteria. Data revealed biodiversity among antagonistic fluorescent pseudomonads associated with the rice rhizosphere. Results presented in this study will help to identify the antagonistic isolates and to determine their mechanisms that mediate antagonism against fungal pathogens of rice.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.10
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• pp.29-34
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• 1992

JFET's with gate lengths ranging from 1$\mu$m to 8.3$\mu$m are successfully fabricated on InP substrate where the long haul (1.3$\mu$m~8.3$\mu$m) OEIC's(OptoElectronic Integrated Circuits) have been made. The pn junction of InP JFET's is made by co-implantation and RTA process. JFET's have etched-mesa-gate structure and the maximum gm larger than 90mS/mm was measured and this is the highest record in JFET's of such structure without S/D n$^{+}$ ion implantation. To maintain maximum g$_m$ should be well controlled the overetch of n-layer which inevitably occurs during etching off the unused p-layer. The I-V characteristic is checked during p-layer etch, for this purpose. A dc voltage gain of 11 is obtained from a preamplifier circuit thus fabricated.

• Journal of Animal Environmental Science
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• v.12 no.1
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• pp.7-12
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• 2006

Ammonia emission from swine production process originates from three major sources: manure storage facility, swine housing, and land application of manure. Most of the ammonia gas that are emitted from swine production operations is the by-product of aerobic or anaerobic decomposition of swine waste by microorganism. Knowing the ammonia emission rate is necessary to understand how management practices or alternative manure handling process could reduce impacts of this emission on the environment and neighbors. Ammonia gas emission from pig slurry is very difficult to predict because it is affected by many factors including wind speed of slurry surface, temperature or pH of the swine slurry, sort breed differences and classes, and diets. This study was carried out to effects of pH and temperature on ammonia gas emission from growing-finishing pig slurry. Treated far slurry in this study were pH and temperature. Results showed that pH of slurry variable changes 5, 6, 7, 8 upon an addition of NaOH and $HNO_3$, respectively. The temperature of the slurry which was contained in a water bath maintained at increasing levels ranging from 10 to $35^{\circ}C$. Ammonia emission rate of influenced pH and temperature such that the increase in pH or temperature resulted to an increase in ammonia emission. The ammonia gas was not detected at pH 5 and 6. Moreover, at a slurry of pH 8, the ammonia ranged from 28 to 60ppm and 8-29 ppm at slurry pH of 7 while temperature was 13 to $33^{\circ}C$. When slurry pH was>6, the ammonia emission was significantly increased according to rise in temperature in contrast to acid treatment of the pH. There was also a significantly increase in ammonia emission relative to slurry pH of 7 to 8. The above findings showed that to effectively reduce ammonia emission from slurry of growing-finishing pigs, the pH and temperature should be maintained a low levels.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.5
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• pp.318-323
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• 2008

We studied on the effects of slurry composting and biofiltration liquid fertilizer (SCBLF) on growth of two-year-old poplar clones planted in a reclaimed land mounding soil. The soil on the experimental site had lower concentrations of both exchangeable cations and salinity than before reclamation. However, the content of organic matter was low compared with the most soils. We applied SCBLF to the poplars six times and 5 L in each time for 80 days. Ten clones of six poplar species or hybrids were tested in this study: Populus alba ${\times}$ P. glandulosa(Clivus, 72-30, 72-31, Bongwha1), P. deltoides ${\times}$ P. nigra(Dorskamp), P. deltoides(Lux) ${\times}$ P. deltoides(Harvard)(97-19), P. euramericana(Eco28, I-476), P. nigra ${\times}$ P. maximowiczii(62-2) and P. Koreana ${\times}$ P. nigra var. italica(Suwon). Growth performance varied more among clones than among species. Average height growth of treated plots was 18% greater than control, and clones Clivus, 97-19, Eco28 and Dorskamp were more vigorous than other clones. Diameter at breast height in treated plots was 41% greater than control, and 97-19, Dorskamp, Eco28 and Clivus were the four best clones in this respect. Mean leaf area of treated trees was 26% greater for control trees. Chlorophyll content was similar between treated and controlled trees. Total nitrogen values in leaves were much higher in treated trees 18%. SCBLF treatment on poplars planted in reclaimed land helped tree growth.