• Journal of Plant Biology
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• v.36 no.3
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• pp.195-201
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• 1993

The room temperature fluorescence induction of chloroplasts was utilized as a probe to locate the site of inhibition by mercury, copper and zinc on PS II by mercury. Inhibitory effect of Hg2+ on electron transport activity was notable as compared with Cu2+ and Zn2+. At concentrations of HgCl2 over 50 $\mu$M, activities of PS II and whole-chain electron transport decreased more than 70%, while that of PS I decreased about 10~30%. This suggests that PS II is more susceptible to Hg2+ than PS I is. In the presence of diphenylcarbazide (DPC), 50 $\mu$M HgCl2 inhibited the reduction of dichlorophenolindophenol (DCPIP) about 50%. Addition of heavy metals induced marked decrease in maximal variable fluorescence/initial fluorescence [(Fv)m/Fo], but no changes in Fo. With various concentrations of heavy metals, changes of chlorophyll a fluorescence emitted by PS II showed gradual decrease in photochemical quenching (qQ), which indicates an increase in reduced state of electron acceptor, QA. Especially, the addition of HgCl2 caused a notable decrease of qQ. In the presence of 50 $\mu$M CuCl2, energy-depended quenching (qE) was completely reduced, whereas in the presence of 50 $\mu$M CuCl2 and ZnCl2 it was still remained. The above results are discussed on the effects of mercury in relation to water-splitting system and plastoquinone (PQ) shuttle system.

• Journal of Korea Soil Environment Society
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• v.5 no.3
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• pp.65-75
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• 2001

This study purpose to elucidate the characteristics of water quality by elevation and groundwater samples has been studied with the samples from 150 selected groundwater represented the watershed of groundwater wells in Cheju Island. The evaluation of the characteristics of water quality utilized the physical and chemical property and the statistical analysis. According to the piper diagram, groundwater in the under 50 m region is shown N $a^{+}$＋ $K^{+}$-C $l^{[-10]}$ type, and that groundwater in the 50~100 m region is shown N $a^{+}$＋ $K^{+}$-HC $O_3$$^{[-10]}$ ＋C $O_3$$^{2-}$ type. and partly N $a^{+}$＋ $K^{+}$-C $l^{[-10]}$ type. In the above 100 m region belongs to N $a^{+}$＋ $K^{+}$-HC $O_3$$^{[-10]}$ ＋C $O_3$$^{2-}$ type. The result of factor analysis, commonly two factors as TDS(Total Dissolved Solid) and the contaminants extracted in the under 50m region and above 100 m region. Three factors were obtained from the result of the factor analysis in the 50~100 m region. Factor 1, consisting of TRS content. Factor 2, consisting of the contaminant and the dissolution of minerals. and Factor 3, consisting of HC $O_3$$^{[-10]}$ content. content.

• Applied Chemistry for Engineering
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• v.4 no.4
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• pp.791-797
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• 1993

The application of the pervaporation process in biotechnology is rapidly growing. A two stage pervaporation process can be applied to the downstream processing of ethanol fermentation. In this paper, the second stage process in which the water-ethanol composition was 50:50 wt.% was investigated in more detail by using Nylon 4 and its blended membranes containing poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA). Nylon 4 membranes were tested for compositions at 25, 30, and $35^{\circ}C$. Nylon 4 membranes had a separation factor of 4.18 with a permeability of $0.69kg/m^2hr$ at water-ethanol composition of 50:50 wt.%, while nylon 4-PVA blended membranes crosslinked by 5 Mrad gamma-ray irradiation showed a higher separation factor of 10.56 with permeability $0.55kg/m^2hr$ at the same composition. Nylon 4 also showed a high separation factor 27.8 at the ethanol-water azeotropic composition among the homopolymer membranes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.8
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• pp.2064-2071
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• 1998

A new digital clock level translator has been designed in order to produce a clock source of the internal logic circuits. The translator output has 50% duty ratio from small sinusoidal input such as TCXO which oscillates itself in poratable components. The circuit consists of positive and negative comparators, RS latch, charge pump, and reference vol- tage generator. It detects pulse width of the output waveform and feedbacks the control signal to the input com-parator. It detects pulse width of the output waveform and feedbacks the control signal to the input com-parator reference, producing output waveform with valid 50% duty ratio of the digital signal level. The designed level translator can be used as a sampling clock source of ADC, PLL and the colck source of the clock synthesizer. The circuit wasdesigned in a 0.8.mu.m analog CMOS technology with double metal, double poly, and BSIM3 circuit simulation model. From our experimental results, a stable operating characteristics of 50 +3% duty ratio was obtained from the sinusoidal input wave of 370 mV.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.41 no.4
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• pp.391-400
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• 2015

In the present study, 50% ethanol extract, the ethyl acetate and aglycone fraction were prepared from mate (Ilex paraguariensis) and their antioxidative ability was evaluated. The yields of extract and fractions were 32.0, 4.48 and 0.82% per dried powder, respectively. Free radical scavenging activities were performed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay and total antioxidant capacity was estimated using luminol-dependent chemiluminescence assay. Free radical scavenging activities ($FSC_{50}$) of 50 % ethanol extract, ethyl acetate fraction and aglycone fraction were 8.83, 5.84 and $6.05{\mu}g/mL$, respectively. Their total antioxidant capacities ($OSC_{50}$) were similar to that of L-ascorbic acid ($1.72{\mu}g/mL$), known as a prominent water soluble antioxidant, in all extracts and 50% ethanol extract ($1.03{\mu}g/mL$) was the most effective. The cellular protective effects on the $^1O_2$-induced cellular damage of erythrocytes were evaluated and the results showed that all extracts were significantly higher than (+)-${\alpha}$-tocopherol at $10{\mu}g/mL$. Especially, the ${\tau}_{50}$ value of aglycone fraction was 5 times higher than (+)-${\alpha}$-tocopherol at $10{\mu}g/mL$ and $50{\mu}g/mL$. The inhibitory effects of the ethyl acetate and aglycone fractions on tyrosinase were similar to arbutin, known as the whitening agent in cosmetics. These results suggest that the extracts of mate have the applicability as antioxidant and anti-aging cosmeceutical ingredients.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.1
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• pp.25-34
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• 2018

This study was conducted to investigate the germination and proteome profile characteristics of wheat seeds treated under various concentrations of abscisic acid (ABA). After-ripening, the seeds of three wheat cultivars (Baegjoong, Keumkang, and Uri) showing different levels of dormancy were used. Germination index and germination rate of the cultivars was higher than 0.95% and 98%, respectively, and these were not significantly different under 0, 10, 30, and $50{\mu}M$ ABA at 7 d after germination. However, the growth of the shoot and radicle was significantly inhibited at 10, 30, and $50{\mu}M$ ABA compared to that at $0{\mu}M$ ABA. Mean ABA content of the embryos of seeds germinated at 0 and $50{\mu}M$ ABA for 7 d was 0.8 and $269.0ngmg^{-1}DW$, respectively. Proteins extracted from embryos germinated for 4 d were analyzed by two-dimensional gel electrophoresis, and proteins showing a difference of 1.5-fold or greater in their spot volume relative to that of $0{\mu}M$ ABA were identified. The expression of four protein spots increased at $50{\mu}M$ ABA and two protein spots were detected only at $50{\mu}M$ ABA; these six proteins were all identified as globulin types. Conversely, the expression of three protein spots decreased at $50{\mu}M$ ABA and were identified as cytosolic glutamine sysnthetase, isocitrate dehydrogenase, and S-adenosylmethionine synthetase 2. In conclusion, ABA did not inhibit the germination rate regardless of pre-harvest sprouting characteristics of the cultivars. However, the growth of the shoot and radicle was significantly inhibited by ABA, most likely through the down regulation of glutamine, methyl group donor, and polyamines biosynthesis, among others, while accompanied by globulin accumulation in the embryos.

• Korean Journal of Plant Resources
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• v.26 no.2
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• pp.149-158
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• 2013

The objective of this study was to investigate the antioxidative capacity of ethanol extracts from Sanguisorbae officinalis L. root (Sanguisorbae radix) in vitro. The concentration of Sanguisorbae radix extract at which DPPH radical scavenging activity was inhibited by 50% was 0.33 mg/mL, which was similar to $IC_{50}$ of ${\alpha}$-tocopherol (0.40 mg/mL), as compared to 100% by pyrogallol as a reference. Total antioxidant status was examined by total antioxidant capacity against ABTS radical reactions. Total antioxidant capacities of Sanguisorbae radix extract were significantly (p<0.05) higher than those of ${\alpha}$-tocopherol. Superoxide scavenging activities of Sanguisorbae radix extract were significantly (p<0.05) higher than those of catechin. Oxygen radical absorbance capacities of Sanguisorbae radix extract were significantly (p<0.05) higher than those of ascorbic acid. Cupric reducing antioxidant capacities of Sanguisorbae radix extract were significantly (p<0.05) higher than those of ${\alpha}$-tocopherol. Sanguisorbae radix extract prevented supercoiled DNA strand breakage induced by hydroxyl radical and peroxyl radical. Total phenolic contents of Sanguisorbae radix extract at concentrations of 0.5 and 5 mg/mL were 0.50 and 3.33 mM gallic acid equivalents, respectively. Sanguisorbae radix extract at concentration of 0.01, 0.1 and 0.5 mg/mL inhibited 0.2 mM tert-butyl hydroperoxide-induced cytotoxicity by 33.8, 79.1 and 96.9%, respectively, in HepG2 cell culture system. Thus, strong antioxidant and cytotoxicity-ihnibiting effects of Sanguisorbae radix extract seem to be due to, at least in part, the prevention from free radicals-induced oxidation as well as high levels in total phenolic contents.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.3
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• pp.280-285
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• 1993

The bioactivity of garlic extract was evaluated, based on the inhibition of soybean lipoxygenase. While the inhibition of lipoxygenase by the chloroform extract (1$_{50}$ value after 10min precirculation, 55mg/$m\ell$) of garlic homogenate shows the property as irreversible inhibitors, the aqueous extract (1$_{50}$ value, 65mg/$m\ell$) appeared to contain mainly reversible inhibitors. In the related study, diallyldislufide and dimethyldisulfide inhibited the enzyme with 1$_{50}$ value of 1.3mM and 18mM, respectively. These disulfides demonstrated both irreversible and reversible patterns of inhibition. In addition, synthetic alliin(allylcysteine sulfoxide) was found to inhibit the enzyme at high concentration (approximately 22%, at 10mM), and its decomposition products showed the irreversible property in the inhibition, in contrast to S-ethyl cysteine sulfoxide which expressed no significant inhibition. Thus, it is suggested that the garlic macerate contains both irreversible and reversible sulfur inhibitors.itors.

• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.751-756
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• 1999

The inhibitory effect of antibiotics on growth of lactobacillus, streptococcus and bifidobacteria was examined to develop the selective media to isolate and enumerate bifidobacteria from the fermented foods containing various lactic bacteria. The growth of lactic bacteria was inhibited seriously but that of bifidobacteria was not inhibited by gentamycin or ripampicin at the concentration of more than $100\;{\mu}g/mL$. However lactic bacteria did not grow in MRS broth containing $50\;{\mu}g/mL$ of ampicillin and the growth inhibition of bifidobacteria occurred. The growth inhibition of bifidobacteria was more severe than lactic bacteria in $100\;{\mu}g/mL$ of fosfomycin. Therefore, the MRS medium containing $80\;{\mu}g/mL$ of neomycin sulfate, $50\;{\mu}g/mL$ of gentamycin, $50\;{\mu}g/mL$ of rifampicin, $15\;{\mu}g/mL$ of nalidixic acid and $3\;{\mu}g/mL$ of lithium chloride was concluded selective for bifidobacteria, but restrictive for the other lactic bacteria present in Kimchi and cheese.

• Journal of Aquaculture
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• v.11 no.2
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• pp.183-191
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• 1998

To substitute fromzed and freeze-dried food for live food in the development of the artificial seedling production of bivalve larvae, the dietary value of live T. suecica was compared with those of freeze-dried T. suecica, frozed T. suecica, live T. suecica (50%)+frozen T. suecica (50%), and live T. suecica (50%)+freeze-dried T. suecica (50%) in the rearing of oyster (Crassotrea gigas) and hen clam (Mactra chinensis) larvae, and manila clam (Tapes philipninarum) spats. Oyster larvae fed live T. suecica showed the highest growth (shell hight $231.9^{\mu}$m) and survival rate (72.6%) and those fed freeze-dried T. suecica showed the lowest growth (shell height $168.9^{\mu}$m) and survival rate (35.3%). However, in the hen clam larvae, there were not significantly different among diet group in growth and survival rate. The small spats of manila clam fed live t. suecica or live T. suecica (50%)+freeze-dried T. suecica (50%) showed higher growth and survival rate than those fed other diet group. In the case of large spats of manila clam, live T. suecica and live T. suecica (50%)+frozen T. suecica (50%) showed better growht. But, survival rates were not different among diet groups. Dietary valuse of frozen and dried T. suecica were different on species and growth stage, and frozen and freeze-dried T. suecica can be partially used as substitute food for T. suecica live T. succica in shellfish hatchery.