• Food Science of Animal Resources
• /
• v.21 no.1
• /
• pp.1-9
• /
• 2001

This study was carried out to investigate the extraction yield, the contents of total phenol substances and antioxidative substances, electron donating abilities, nitrite scavenging abilities of water and ethanol extracts from Cassia tora L. and Pueraria thunbergiana and antioxidative activity of water and ethoanol extract from Cassia tara L. Tatal phenol substances of water and ethanol extract from Cassia tora L. and Pueraria thunbergiana showed nearly the same levels, and the antioxidative substances of water and ethanol extract from Pueraria thunbergiana has as much as two times higher than those from Cassia tara L.. The nitrite scavenging abilities were measured at pH 1.2, 3.0, 4.2 and 6.0, respectively. Water and ethanol extracts from Cassia tora L showed 14.9%∼22.3% and 49.1%∼56.7%, and those from Pueraria thunbergiana revealed 57.7%∼61.0% of nitrite scavenging abilities, respectively. Especially the extracts from Pueraria thunbergiana showed higher pH dependence than those from Cassia tora L. The electrol donating abilities of water extract from Cassia tora L. were higher than those from Pueraria thunbergiana, and vice versa in the case of ethanol extracts. In the antioxidative activitiy of extracts from Cassia tora L. against linoleic acid during storage of 20 days at 50$^{circ}C$, peroxide values at the addition level of 5mg and 10mg were consoderably lower than 2mg although peroxide value increased above 375 after 12days of storage compared with the control(BHA-added) of 129 at 8days.

• Korean Journal of Optics and Photonics
• /
• v.25 no.2
• /
• pp.95-101
• /
• 2014

When voltage is applied on the metal layer of a surface plasmon resonance (SPR) sensor, electric field excitation causes charge accumulation on the metal surface. This alters not only the optical properties of the metal but also the SPR angle. In this study we investigate this effectby performing experiments using solutions of various pH values, and we obtain the relation between total surface charge and SPR angle. The curves for the various pH conditions become coincident. We compare our results to those from an earlier space charge layer (SCL) model, and suggest a modified SCL model which explains our result well. This result will be useful in applications of SPR sensors, and in studying the optical properties of thin metal layers.

• Journal of the Korean Chemical Society
• /
• v.36 no.4
• /
• pp.540-545
• /
• 1992

Kinetics and mechanism on the solvent extraction of nickel(Ⅱ) with 8-hydroxyquinoline (HOx) was studied spectrophotometrically. Absorbance variation was measured by changing the 8-hydroxyquinoline concentration in the chloroform organic phase and the pH values in the aquous phase. By analyzing absorbance data the reaction rate was found to be the first order for 8-hydroxyquinoline concentration and the inverse first one for [H$^+$]. Therefore the rate determining step of the extraction reaction is the formation of the one-to-one metal chelate NiOx$^+$ and the rate equation is as follows; -d[Ni$^{2+}$]/dt = k[Ni$^{2+}$][Ox$^-$] = k'[Ni$^{2+}$][HOx]$_0$/[H$^+$]. The value of k' was evaluated from the slope of plot of log [Ni$^{2+}$]$_0$/[Ni$^{2+}$]$_t$ versus time and the rate constant k was calculated according to the equation k' = k ${\times}$ K$_{HOx}$ / K$_{D,HOx}$. From the temperature dependence of the extraction rate, the activation energy E$_a$ = 6.26 kcal/mol is calculated, and activation parameters, ${\Delta}$G$^{\neq}_{298}$ = 6.59 kcal/mol, ${\Delta}$H$^{\neq}_{298}$ = 5.68 kcal/mol, ${\Delta}$S$^{\neq}_{298}$ = -3.09 eu/mol are estimated.

• Journal of the East Asian Society of Dietary Life
• /
• v.23 no.6
• /
• pp.723-732
• /
• 2013

We investigated the inducing effects of Rubus coreanus extract (RCE) on apoptosis and its related gene expressions in human breast cancer cells. MDA-MB-231 cells were cultured in the presence of 0, 200, 300, and $400{\mu}g/mL$ RCE for 24h. MTT assay demonstrated that relative cell viability measured a decrease in a dose-dependent manner (p<0.05). This dependency was also found in the increasing levels of cell death by a dual staining with Hoechst 33322 and propidium iodide (p<0.05). These close associations was also observed by different stages of apoptotic processes, as shown by an Apoptosis Detection Kit. To determine whether the alterations in such cell activities obtained above cause the induction of apoptotic genes, PT-PCR was performed expressions of both Bcl-2 and Bax mRNAs. The Bcl-2/Bax ratio which is an important indicator of apoptosis, was found to have significantly decreased dose dependence (p<0.05). Western blot analysis also demonstrated that Caspase-3 significantly increases in a dose-dependent manner (p<0.05) in addition to similar alterations of other proteins examined. Taken these results together, the ethanolic RCE used induces a reduction in cell viability along with increased membrane permeability. This leads to a precautious apoptotic process and, subsequently, cell death through the apoptotic pathway involving Bax and Caspase-3 in human breast cancer MDA-MB-231 cells.

• Bulletin of the Korean Chemical Society
• /
• v.24 no.6
• /
• pp.792-796
• /
• 2003

Polychlorinated dibenzo-p-dioxins (PCDDs) are extremely toxic and persistent environmental pollutants. Their chemical reactivities and other physicochemical/biological properties show a strong dependence on the chlorination pattern. With increasing the number of chlorines, dioxin congeners become more electronegative and gain higher electron affinities. The vertical electron affinities (VEA) are related with the LUMO energies of neutral molecules. LUMO energies of all PCDD congeners were calculated at the B3LYP/6-31G** level and those of some selected congeners at the level of B3LYP/6-311G**//B3LYP/6-31G** and B3LYP/cc-pvtz/ /B3LYP/6-31G**. The total energies of neutral and anionic species for dibenzo-p-dioxins (DD), 1469-TCDD, 2378-TCDD, and OCDD were calculated at the level of B3LYP/6-31G**, B3LYP/aug-cc-pvdz, and B3LYP/ aug-cc-pvtz//B3LYP/6-31G**. By using the four congeners with D2h symmetry as reference molecules, we could estimate VEA (B3LYP/aug-cc-pvdz) of 75 PCDD congeners based on the linear correlations between LUMO energy and VEA (B3LYP/6-31G**) and between VEA (B3LYP/6-31G**) and VEA (B3LYP/aug-ccpvtz// B3LYP/6-31G**). Results show that all PCDDs with the number of Cl ≥ 3 have positive electron affinities. The PCDD electron affinity values provided in this work can be a useful data set in understanding the congener-specific reactivities of dioxins in various environmental media.

• Korean Journal of Pharmacognosy
• /
• v.25 no.3
• /
• pp.238-248
• /
• 1994

The hypoglycemic and metabolic effects of Commelina communis L. extract were investigated in alloxan induced diabetic rats. The increased blood glucose level in the diabetic rats was significantly reduced and the loss of body weight was recovered with the treatment of the plant protein fractions($30{\sim}70%$ ammonium sulfate precipitates). Administration of the plant protein fractions elicited the significant increase of glucose-6-phosphate dehydrogenase (G-6-P DH) activity and liver weight which were decreased in the diabetic rat liver. G-6-P DH was partially purified from extract- or insulin-treated diabetics, diabetic control, and normal rat liver and studied for the biochemical properties. The $K_m$ value(9.002 mM) of diabetic rat liver enzyme was greatly higher than that (0.033 mM) of normal enzyme indicating the affinity of enzyme for the substrate was significantly reduced in the diabetic rat liver. This reduced affinity of enzyme for the substrate in the diabetic rat was recovered in the extract- or insulin-treated rat liver enzyme having 0.164 or 0.208 mM of their $K_m$ values, respectively. Although there was no significant difference in the optimum pH(6.0) and optimum temperature($37^{\circ}C$) of enzyme among the experimental groups, the dependence of their activities on pH appeared to be slightly resistant in the extract- or insulin-treated group compared to the diabetic group. In order to investigate the antigenicity of rat liver enzyme among experimental groups, enzyme-linked immunosorbent assay was carried out by using anti-G-6-P DH anti-serum. Absorbance(0.102) shown in the normal rat liver was reduced even below zero in the alloxan-diabetic rat liver, but increased again in the extract- or insulin-treated rat liver(0.096 or 0.118, respectively). The result of this study suggested that G-6-P DH may be used as a marker enzyme to diagnose and to indicate the progress of the diabetics, and the hypoglycemic effect of the extracts of Commelina communis L. was certainly associated with action or mode of G-6-P DH on the rat liver.

• Korean Journal of Materials Research
• /
• v.20 no.4
• /
• pp.210-216
• /
• 2010

This paper investigates the dependence of a-Si:H/c-Si passivation and heterojunction solar cell performances on various cleaning processes of silicon wafers. It is observed that the passivation quality of a-Si:H thin-films on c-Si wafers depends highly on the initial H-termination properties of the wafer surface. The effective minority carrier lifetime (MCLT) of highly H-terminated wafer is beneficial for obtaining high quality passivation of a-Si:H/c-Si. The wafers passivated by p(n)-doped a-Si:H layers have low MCLT regardless of the initial H-termination quality. On the other hand, the MCLT of wafers incorporating intrinsic (i) a-Si:H as a passivation layer shows sensitive variation with initial cleaning and H-termination schemes. By applying the improved cleaning processes, we can obtain an MCLT of $100{\mu}sec$ after H-termination and above $600{\mu}sec$ after i a-Si:H thin film deposition. By adapting improved cleaning processes and by improving passivation and doped layers, we can fabricate a-Si:H/c-Si heterojunction solar cells with an active area conversion efficiency of 18.42%, which cells have an open circuit voltage of 0.670V, short circuit current of $37.31\;mA/cm^2$ and fill factor of 0.7374. These cells show more than 20% pseudo efficiency measured by Suns-$V_{oc}$ with an elimination of series resistance.

• BMB Reports
• /
• v.32 no.3
• /
• pp.232-238
• /
• 1999

Sex differences in the induction of microsomal cytochrome P-450 (CYP) and the activities of several related enzymes of Sprague-Dawley rats treated with 1-bromopropane (1-BrP) were investigated. Male and female rats were exposed to 50, 300, and 1800 ppm of 1-BrP per kg body weight (6 h a day,S days a week, 8 weeks) by inhalation. The mean body weight of 1-BrP treated groups increased according to the day elapsed, but four and five weeks respectively after the start of the exposure, the mean body weight of male and female rats had significantly reduced in the group treated with 1800 ppm 1-BrP compared with the control group (p<0.01). While the relative weights of liver increased in both sexes, statistical significance in both sexes was found only in the group receiving 1800 ppm/kg of 1-BrP (p<0.01). The total contents of CYP, $b_5$, NADPH-P-450 reductase, NADH $b_5$ reductase, ethoxyresorufin-O-deethylase (EROD), pentoxyresorufin-O-dealkylase (PROD), and p-nitrophenol hydroxylase (pNPH) activities were examined for the possible effects of 1-BrP. No significant changes in the CYP and $b_5$ contents, NADPH-P-450 reuctase, NADH $b_5$ reductase, ethoxyresorufin-O-deethylase (EROD), and pentoxyresorufin- O-dealkylase (PROD) were observed between the control and treated groups. The activity of pNPH increased steadily with the increase in the concentration of 1-BrP in both sexes, but was significantly increased only in the 1800 ppm-treated group of male rats (p<0.05). When Western blottings were carried out with three monoclonal antibodies (MAb 1-7-1, MAb 2-66-3, and MAb 1-98-1) which were specific against CYP1A1/2, CYP2B1/2, and CYP2E1, respectively, a strong signal corresponding to CYP2E1 was observed in microsomes obtained from rats treated with 1-BrP. Glutathione S-transferase (GST) activity and the content of lipid peroxide significantly increased in the treated groups compared with the control group (p<0.05). These results suggest that 1-BrP can primarily induce CYP2E1 as the major form and that GST phase II enzymes play important roles in 1-BrP metabolism, showing sex-dependence in the metabolic mechanism of 1-BrP in the rat liver.

• Analytical Science and Technology
• /
• v.6 no.5
• /
• pp.471-477
• /
• 1993

The novel macrocylic ligand {(4, 5):(13, 14)-dibenzo-6, 9, 12-trioxa-3, 15, 21, -triazabicyclo [15. 3. 1]heneicosa-(1, 17, 19)(18, 20, 21) triene: HDBPDA} was synthesized, and protonable constants of the ligand and the complex stability constants with alkali metals alkaline earth metals were determined. We evaluated the resolution factor(${\Delta}$) from equation that inducing from stability constants(pK). Also, this ligand was grafted on chloromethylated styrene-divinyl benzene(Merrifield resin) for HDBPDA, ion exchanger. Alkali and alkaline earth metal ions were separated using water by the column chromatography with this ion exchanger. Selectivity(${\alpha}$) and resolution(Rs) of alkali and alkaline earth metal ions were measured from the elution curves chromatogram. The selectivity and resolution values of the various ions calculated from the elution curves were compared with those abtained from pK values. The results were in a good agreement between tow methods. Ion exchange capacity of the resin were determined using the alkali and alkaline earth metal ions and pH dependence of capacity was also discussed.

• Korean Journal of Food Science and Technology
• /
• v.26 no.2
• /
• pp.110-116
• /
• 1994

In order to study the effects of enzyme modification on the physico-chemical and functional properties of myofibrillar protein prepared from the frozen sardine, Sardinops melanostica, the protein was hydrolyzed with pepsin under the enzyme-substrate ratio 1:100 at $37^{\circ}C$ and pH 1.65 for 1, 4, 8, 12, and 24 hr, respectively. The properties of pepsin-modified sardine myofibriliar protein were determined. The extents of proteolysis with pepsin as a fuction of time was showed a typical enzyme hydorlysis curve with an initial region of 4 hour period followed by plateau region. The SDS-acrylamide slab gel electrophoresis patterns of pepsin-modified proteins showed mainly disappearances of minor protein bands, but no changes of main protein bands. The gel filtration patterns through Sephadex G-75 of sardine myofibrillar protein showed two big peaks and three small peaks. All the small peaks were disappearanced by proteolysis with pepsin in one hour. and during the period of proteolysis the fast big peak became gradually smaller and the late big peak eluted more slowly. By proteolysis, the emulsifying activity and emulsifying capacity of sardine myofibrillar protein were all decreased. The effects of pepsin-modification on emulsifying capacity were greater than those on emulsifying activity of protein. The aeration capacity of the protein was increased about 1.9 folds and the foam stability decreased to 0.6 folds of control by pepsin-modification. The pepsin-modified sardine myofibrillar proteins showed about 0.6 folds of heat coagulation and 1.4 folds of viscosity of control. The pH dependence of solubilities of sardine myofibrillar protein showed two isoelectric areas of pH 5 and 9. The pepsin-modified protein showed more clear pH dependences at the early stage but not at the late stage of proteolysis.