• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
• /
• v.15 no.1
• /
• pp.96-126
• /
• 2002

In the course of screening natural extracts for hair growth, we found that the extract of dried root of Sophora flavescens has the prominent hair growth promoting effect. After topical application of Sophora flavescens extract to the back of C57BL/6 mice, the earlier conversion of telogen-to-anagen phase was induced. In addition, the Sophora flavescens extract revealed to possess potent inhibitory effect on $5{\alpha}$-reductase Ⅰ and Ⅱ activity. The growth of dermal papilla cells and mouse vibrissae hair follicle cultured in vitro, however, was not affected by Sophora flavescens extract treatment. RT-PCR analysis showed that Sophora flavescens extract induced mRNA levels of growth factors such as insulin-like growth factor-Ⅰ and keratinocyte growth factor in dermal papilla cells, suggesting hair growth promoting effect of Sophora flavescens extract is mediated through inhibition of $5{\alpha}$-reductase type Ⅱ activity and the regulation of growth factors in dermal papilla cells. Furthermore, Sophora flavescens extract also showed anti-bacterial effect on Propionibacterium acnes. These results suggest that Sophora flavescens can be used as a potent treatment agent for helping hair growth stimulation and acne inhibition.

• Journal of Power System Engineering
• /
• v.11 no.1
• /
• pp.115-120
• /
• 2007

The effect of grain size on the damping capacity of Fe-26Mn-2Al alloy studied in this paper has been investigated after changing the microstructure by cold rolling and changing grain size. Micro structures in Fe-26Mn-2Al at room temperature consist of a large quantity of austenite and a small quantity of ${\varepsilon}\;and\;{\alpha}'$ martensite. And ${\varepsilon}\;and\;{\alpha}'$ martensite was increased by increasing the degree of cold rolling. The content of deformation induced martensite was increased with increasing the degree of cold rolling. Damping capacity was linearly increased with increasing ${\varepsilon}$ martensite content, which suggests that stacking faults and ${\varepsilon}$ martensite variant boundaries are the principle damping sources. With increasing the grain size in Fe-26Mn-2Al alloy, the damping capacity was increased due to increasing the volume fraction of ${\varepsilon}$ martensite by decrement in stability of austenite phase. With decreasing the grain size, the content of deformation induced martensite was decreased and the damping capacity was decreased.

• Journal of the Korean Chemical Society
• /
• v.39 no.12
• /
• pp.896-901
• /
• 1995

The critical micelle concentrations(CMC$^*$) of the mixed surfactant systems of Sodium dodecyl sulfate(SDS) with Tetraethylene glycol monododecyl ether(TGME) in the aqueous solutions of NaCl at $25^{\circ}C$ were determined as a function of the overall mole fraction of $SDS(\alpha1)$ by the use of surface tension method. Various thermodynamic parameters for the micellization of SDS/TGME mixed surfactant systems were calculated and analyzed by means of the equations derived from the nonideal mixed micelle model, based on the pseudo-phase separation model.

• Journal of Advanced Marine Engineering and Technology
• /
• v.31 no.4
• /
• pp.377-384
• /
• 2007

A backscatter Kikuchi diffraction attachment to an SEM enables the convenient investigation of grain orientations on bulk or micro surface. Their relation to micro structural features gives insight into many aspects of anisotropic materials properties. In micro area such as Micro Electro Mechanical Systems(MEMS) devices is required in order to improve understanding of how they may be expected to perform upon the micro scale. Electro Back Scatter Diffraction (EBSD) helps us to find uniform area as MEMS material. The ${\gamma}-TiAl$ has two different lamellar structures ${\gamma}/{\alpha}2-Ti_3Al$ phase which have shows $\{111\}{\gamma}//\{0001\}{\alpha}2$ plane indexing. The micro size testing specimen was successfully made by this structural relation. Interlamellar structure specimen averagely show $20{\sim}25%$ lower fracture toughness value compare with translamellar specimens Moreover micro fracture surface and micro crack progress were observed.

• Journal of the Korean Chemical Society
• /
• v.34 no.1
• /
• pp.69-75
• /
• 1990

An ion-association chromatography was applied for the separation and determination of individual rare earth elements (REE) contained in mineral monazite. Prior to the determination, the group separation of REE was achieved by a cation exchange column of Dowex 5OW-X8 resin. The quantitative recovery of REE by the resin column, free from coexisting elements in monazite, was confirmed with radioactive tracers as well as with ICP-MS. Individual REE at ppm level was separated on reversed-phase column ($\mu$-Bondapak $C_{18}$) using gradient elution from 0.05 to 0.3 M $\alpha$-hydroxyisobutyric acid at pH 4.6. The individual REE was detected at 546 nm following post-column reaction with PAR (4-(2-pyridylazo)-resorcinol monosodium salt).

• Journal of the Korean Ceramic Society
• /
• v.37 no.4
• /
• pp.320-326
• /
• 2000

Development of texture in SiC materials by hot-pressing and subsequent annealing was studied. Crystallographic texture type was characterized by measuring X-ray pole figures on the perpendicular plane to the hot-pressing direction. Observed all pole figures were nearly axially symmetric (fiber texture). In case of ${\beta}$-SiC materials, the pole density of basal plane (0004) increased as annealing time increased, in contrast, other planes (hkil) of ${\beta}$-SiC materials and all planes of ${\alpha}$-SiC materials nearly remained unchanged. In the case of ${\beta}$-SiC materials, therefore, a weak texture of (0001) plane at the normal direction took place in the 8h annealed samples, resulting from grian growth. The fracture toughness values of ${\alpha}$-SiC materials measured in both planes parallel and perpendicular to the hot-pressing direction were very similar. However, the fracture toughness of ${\beta}$-SiC materials measured parallel to the hot-pressing direction were higher than that measured perpendicular to the hot-pressing derection, relatively, because of the texture and the microstructure anisotropy.

• Journal of Powder Materials
• /
• v.11 no.3
• /
• pp.247-252
• /
• 2004

Recently, it has been found that mechanical alloying (MA) facilitates the nanocomposites formation of metal-metal oxide systems through solid-state reduction during ball milling. In this work, we studied the MA effect of Fe$_{3}$O$_{4}$-M (M = Al, Ti) systems, where pure metals are used as reducing agents. It is found that composite powders in which $Al_{2}$O$_{3}$ and TiO$_{2}$ are dispersed in $\alpha$-Fe matrix with nano-sized grains are obtained by mechanical alloying of Fe$_{3}$O$_{4}$ with Al and Ti for 25 and 75 hours, respectively. It is suggested that the large negative heat associated with the chemical reduction of magnetite by aluminum is responsible for the shorter MA time for composite powder formation in Fe$_{3}$O$_{4}$-Al system. X-ray diffraction results show that the reduction of magnetite by Al and Ti if a relatively simple reaction, involving one intermediate phase of FeAl$_{2}$O$_{4}$ or Fe$_{3}$Ti$_{3}$O$_{10}$. The average grain size of $\alpha$-Fe in Fe-TiO$_{2}$ composite powders is in the range of 30 nm. From magnetic measurement, we can also obtain indirect information about the details of the solid-state reduction process during MA.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.07a
• /
• pp.94-98
• /
• 2000

Polycrystalline SBTN ferroelectric thin films were prepared by sol-gel method with various Nb mole ratios on Pt/ $SiO_2$/Si (100) substrates. The films were annealed at different temperatures and characterized in terms of phase and microstructure. Relatively a well saturated hysteresis pattern was obtained at x =0.2 in S $r_{0.8}$B $i_{2.3}$(T $a_{1-x}$ N $b_{x}$)$_2$ $O_{9+}$$\alpha$/ thin films. At an applied voltage of 5V, the dielectric constant ($\varepsilon$$_{r}$) and dissipation factor (tan $\delta$) of typical S $r_{0.8}$B $i_{2.3}$(T $a_{1-x}$ N $b_{x}$)$_2$ $O_{9+}$$\alpha$/ thin film (x=0.2) were about 236.2 and 0.034. Measured remanent polarization (2Pr) and coercive field (Ec) were 4.28C/c $m_2$, and 38.88kv/cm respectively. No fatigue was observed up to 6$\times$10$_{10}$ switching cycles at 5V and the normalized polarization reduced by a factor of only 4%.%. 4%.%. 4%.%.%.%.%.

• Electrical & Electronic Materials
• /
• v.10 no.2
• /
• pp.97-104
• /
• 1997

In this paper, in order to investigate the behavior of charged particles on (Sr.Ca)TiO$_{3}$ ceramics with paraelectric properties, the characteristics of electrical conduction and thermally stimulated current was measured respectively. As a result, the conduction mechanism is divided into three regions having different mechanism as the current increased. The region I below 200[V/Cm] shows the ohmic conduction. The region B between 200[V/cm] and 2000[V/cm] can be explained by the Poole-Frenkel emission theory, and the region III above 2000[V/cm] is dominated by the tunneling effect. The three peaks of TSC were obtained at the temperature of -20[.deg. C], 20[.deg. C] and 80[.deg. C], respectively. The origins of these peaks are that the .alpha. peak observed at -20[.deg. C] looks like to be ascribed to the ionization excitation from donor level in the grain, and the .alpha.' peak observed at 20 [.deg. C] appears to show up by hopping conduction of the trapped carrier of border between the oxidation layer and the grain, and the .betha. peak observed at 80[.deg. C] seems to be resulted from hopping conduction of existing carrier in the trap site of the border between the oxidation and second phase.

• Natural Product Sciences
• /
• v.14 no.4
• /
• pp.249-253
• /
• 2008

Two oleanane-type triterpenes (1, 2) and their glycosides (4-6), and one ursane-type triterpene (3) have been isolated from a methanolic extract of Patrinia saniculaefolia Hemsley (Valerianaceae) through repeated silica gel and reversed-phase C-18 column chromatography. Their chemical structures were determined as oleanolic acid (1), oleanonic acid (2), 23-hydroxyursolic acid (3), 3-O-${\alpha}$-L-arabinopyranosyl-oleanolic acid (4), 3-O-${\beta}$-D-glucopyranosyl-oleanolic acid (5), and oleanolic acid 3-O-[${\alpha}$-D-xylopyranosyl-($1{\rightarrow}3$)-${\beta}$-D-glucuronopyranoside-6-O-butyl-ester] (6) on the basis of their MS, $^1H$-, and $^{13}C$-NMR spectral data. All compounds were isolated from the whole plant of the P. saniculaefolia for the first time. These compounds were examined for their anti-complement activity against the classical pathway of the complement system. Among them, compounds 1 - 3 exhibited anti-complement activity with $IC_{50}$ values of 470.1, 212.2, and 121.0 ${\mu}M$, respectively, whereas compounds 4 - 6 were inactive. These results suggest that the carbonyl or hydroxy group at C-3 in the oleananeand/or ursane-triterpenes are important for the anti-complement activity against the classical pathway.