• Korean Journal of Fisheries and Aquatic Sciences
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• v.25 no.5
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• pp.392-398
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• 1992

Field study on the sporogenesis periods of 16 red algae growing at the intertidal zone of Daesongri was conducted from April 1987 to March 1988, obseuing the occurence of carposporic and tetrasporic fronds. The period of Gloiopeltis furcata was in spring and summer; that of Laurencia intermedia, Laurencia undulata and Rhodymenia intricate in summer; that of Chondria dasyphylla and Hypnea charoides in autumn; that of Carpopeltis affinis, Pachymeniopsis lanceolata, Chondrus ocellatus, Awosorium polyneunm, Gymnogongrus flabelliformis, Gigartina intermedia, Champia parvula and Ceramium paniculatum in summer and autumn. Of the species, G. flabelliiformis, G. intermedia and R. intricate only matured the carposporic phase, and P. telfairiae, H charoides, C. parvula and C. paniculatum did the tetrasporic phase. But the carposporic phase of G. flabelliformis and the tetrasporic phase of C. paniculatum were not occured in Kori area where water temperature was 3 C higher than that in Daesongri. In that area they only matured the other phase. This suggests that the life history is rarely complete in nature and water temperature is a important factor influencing on the sporogenesis. Also it was observed in C. affinis, C. ocellatus and S. latiuscula that the period of one phase is much longer than that of the other phase. But in most of species with both phases, tatrasporic and caropsporic, the former phase appeared a month later than the latter phase. In addition, their biomass became maximum just before sporgenesis, and then gradually decreased with release of reproductive cells.

• Asian-Australasian Journal of Animal Sciences
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• v.2 no.2
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• pp.77-84
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• 1989

Twenty-four Hereford steers, 22 months old and a mean liveweight (${\pm}\;s.e.$) of $250\;{\pm}\;7\;kg$ were used in an experiment to evaluate over 42 days two rates of copra meal supplementation to cattle on a low N ($8.6\;{\pm}\;0.9$ g N/kg dry matter (DM)), low digestible ($45\;{\pm}\;5.2%$ DM) native pasture hay. Steers given the two rates (500, 1000 g/steer/day; i.e. 500C, 1000C) were compared to steers on a non-supplemental diet and to the effects on steers of supplemental urea (30g/steer/day; 30U) or with copra meal (500 g/steer/day; 500C.U), or of cottonseed meal (500 g/steer/day; 500S). Liveweight change was increased (P<0.01) by all of the supplements except by supplemental urea. The most effective treatment, 1000C, increased significantly (P<0.01) liveweight change (946 g/day) in steers above all supplements except those steers given 500C.U (718 g/day). Hay intake per unit liveweight was increased (P<0.05) by 7% by the 30U and 500C.U treatment, and by 9% by 500C; this group having the highest supplements, being greatest (P<0.05) for the 1000C group (6.0 g feed intake/g gain) and least for the 500S supplemented group (11.5 g/g gain). Efficiency was lowest (18.6 g/g gain) for the non-supplemented steers on the basal hay diet. Copra meal N was less degradable (i.e. 29%) in nylon bags over 15 hours in the rumen than was cottonseed meal N (37%), and rumen ammonia concentrations were lower (P<0.05) in cattle supplemented with copra meal (25, 27 mg N/L) than in cattle given urea (36 mg N/L) or cottonseed meal (39 mg N/L). It is concluded that copra meal at a daily rate of 500 g/head, and with rumen soluble nitrogen from urea, is an effective supplement for improving growth of cattle on a low quality forage.

• Microbiology and Biotechnology Letters
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• v.39 no.1
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• pp.93-96
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• 2011

It has been shown that a nucleotide substitution at position 770 in Escherichia coli 16S rRNA, which is implicated in forming the evolutionary conserved B2c intersubunit bridge, has a detrimental effect on ribosome function. In order to isolate second-site revertants that complement ribosomes containing C770G, we performed a random mutagenesis of the 16S rRNA gene and selected clones that could produce more CAT protein translated by specialized ribosome. One of the clones contained two nucleotide substitutions at positions 569 and 904 (C569G and U904C) and these mutations partially complemented the loss of protein-synthesis ability caused by C770G. Further studies using the isolated revertant will provide information about which part of 16S rRNA is interacting with C770 and the consequence of the structure formed by these interactions in the process of protein synthesis.

• Parasites, Hosts and Diseases
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• v.30 no.2
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• pp.141-146
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• 1992

A total of 197 fecal specimens was prepared for quantitative examination of helminth eggs by modified Kato's cellophane thick smear (M.C.T.S.) and Stoll's dilution egg counting technique (D.E,C.T.). The comparative effectiveness of two techniques was evaluated and conversion function was deduced. The average time required for the microscopic examination on one slide by M.C.T.S. was 12.6 minutes and that of D.E.C.T. was 14.6 minutes. M.C.T.S. showed lower false negative rate than D.E.C.T in light worm burden cases. Functions to convert the counts obtained by M.C.T.S. to E.P.G. by Stoll's dilution egg counting technique were $47.86{\times}10^{0.87{\;}logM.C.T.S.},{\;}$ in A. lumbricoides, $41.69{\times}10^{0.82{\;}logM.C.T.S.}$ in T. trichiura and $63.10{\times}10^{0.85{\;}logM.C.T.S.}$ in C. sinensis. It was suggested M.C.T.S. be better than D.E.C.T. for the quantitative examination of intestinal helminthiases such as A. lumbricoides, T. trichiura, and C. sinensis infections even in the cases with low worm burden.

• Journal of Food Hygiene and Safety
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• v.13 no.4
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• pp.441-447
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• 1998

This study was performed to investigate the changes of amount of S. typhimurium during cooking processes using pork and japchae (a Korean food which is made from meat, vegetables and noodles), and to support a practical application to develop a hazard analysis critical control point (HACCP) model. The pork was purchased in a retail shop, cut ($0.5\;cm\;{\times}\;10\;cm\;{\times}\;10\;cm$, 25 g), tested for Salmonella contamination (results: negative), inoculated with S. typhimurium ($10^{7}\;CFU/g$), then treated in various conditions related to cooking. Mter thawing for 24 hours in various conditions, the number of S. typhimurium was increased to $10^{10}\;CFU/g$ at a refrigerated temperature ($4~10^{\circ}C$), and to $10^{21}\;CFU/g$ at room temperature ($22~29^{\circ}C$). Mter thawing in a microwave oven for 40 seconds, the number of S. typhimurium increased to $10^{8}\;CFU/g$. During the thawing period, the number of S. typhimurium increased over time. At the refrigerated temperature, the number of the bacteria was $10^{10}\;CFU/g$ after 24 hours, $10^{13}\;CFU/g$ after 48 hours, and $10^{20}\;CFU/g$ after 72 hours. At room temperature the number of bacteria reached $10^{11}\;CFU/g$ in 2 hours, $10^{15}\;CFU/g$ in 4 hours, $10^{16}\;CFU/g$ in 8 hours, $10^{18}\;CFU/g$ in 12 hours, and $10^{21}\;CFU/g$ in 24 hours. Mter cooking in a frying pan (150{\pm}7^{\circ}C$) for 3 minutes, the bacterial count was $10^{16}\;CFU/g$. After cooking in hot water for 20 minutes, the bacterial count was $10^{7}\;CFU/g\;at\;60^{\circ}C,\;10^{6}\;CFU/g\;at\;63^{\circ}C,\;and\;10^{4}\;CFU/g\;at\;65^{\circ}C$. The fried pork was mixed with cooked vegetables, noodles, sesame oil, sesame seeds, and seasonings to make Korean japchae. This process took $10{\pm}2$ minutes. The bacterial count in the japchae increased to $10^{7}\;CFU/g$ from the count of $10^{6}\;CFU/g$ of the fried pork before it was mixed with the other ingredients. These results indicate that the amount of S. typhimurium is effected by various different cooking processes. This study can suggest that pork should be cooked in water at over $65^{\circ}C$ for 20 minutes in order to prevent food poisoning, if the pork is contaminated with S. typhimurium. The presence of S. typhimurium in the raw pork is identified in an HA for japchae, and the primary CCP for japchae is inadequate cooking (cooking method and time/temperature). We need to standardize time-temperature-size and amount of pork in cooking japchae, because pork is usually cooked in ordinary frying pans when we make this food.

• Bulletin of the Korean Chemical Society
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• v.24 no.8
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• pp.1141-1149
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• 2003

The structures and gas-phase ionization energies (ΔG°) of Meldrum's acid (I) and related cyclic (II-VI) and acyclic compounds (VII-IX) are investigated theoretically at the MP2/6-31+$G^*$, B3LYP/6-31+$G^*$, B3LYP/6- 311+$G^{**}$, B3LYP/6-311++G(3df,2p) and G3(+)(MP2) levels. Conformations of three neutral cyclic series vary gradually from boat (Meldrum's acid, I), to twisted chair (II) and to chair (III) as the methylene group is substituted for the ether oxygen successively. The preferred boat form of I can be ascribed to the two strong $n_O$ → σ* c-c antiperiplanar vicinal charge transfer interactions and electrostatic attraction between negatively charged C¹ and positively charged C⁴at the opposite end of the boat. All the deprotonated anionic forms have half-chair forms due to the two strong $n_C$ → π* c=0 vicinal charge transfer interactions. The dipole-dipole interaction theory cannot account for the higher acidity of Meldrum's acid (I) than dimedone (III). The origin of the anomalously high acidity of I is the strong increase in the vicinal charge transfer ($n_C$ → π* c=0) and 1,4-attrative electrostatic interactions (C¹↔C⁴) in the ionization (I → $I^-$ + $H^+$). In the acyclic series (VII-IX) the positively charged end atom, C⁴, is absent and the attractive electrostatic stabilization (C¹↔C⁴) is missing in the anionic form so that the acidities are much less than the corresponding cyclic series.

• Food Science and Preservation
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• v.18 no.3
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• pp.310-318
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• 2011

The main objective of this study was to manufacture black onions using different methods, and to analyze the color and physiological and antioxidant activities of their water extracts. Black onions were produced via high-temperature aging (70, 80, and $90^{\circ}C$). At $90^{\circ}C$, onions with different weights (large, 90-L; medium, 90-M; and small, 90-S) and small onions with different appearances (whole, 90-S-W; cut, 90-S-C; and peeled, 90-S-P) were also produced. The colorimetry measurements showed that the extract from the 90-S-C black onion had the highest ${\Delta}E$ value among all the extracts from all the black onion groups. The extract from the 90-S-C black onion had a 3.3 times higher total phenol content than that from the $70^{\circ}C$ black onion extract (11.62 and 3.51 mg/g, respectively). The DPPH radical scavenging activities of the extracts from 90-S-W, 90-S-C, and 90-S-P were higher than those of the other black onion extracts, and the 90-S-C black onion extract had the highest level of 48.3% (at the concentration of 10 mg/ml). The 90-S-C black onion extract also had the highest level of antioxidant activities (ABTS radical scavenging activity, 0.84 mg AA eq/100 g, and nitrite scavenging ability, 49.8%). These results clearly demonstrated that 90-S-C was the best among the conditions used and that the water extract of the 90-S-C black onions had a significantly higher level of antioxidant activities than the extracts from the other black onions.

• Bulletin of the Korean Chemical Society
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• v.20 no.5
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• pp.559-566
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• 1999

Gas-phase alkylations of delocalized ambident anions, Y---CH---X- where X, Y=CH2, O, or S, have been investigated theoretically at the MP2/6-31+G*//MP2/6-31+G* and QCISD/6-31+G*//MP2/6-31+G* lev-els. O-and S-alkylations (X=O and S) are more favored kinetically by ΔE^≠ = 4.6 and 9.8 kcal mol-1 than the respective C-alkylations even though they are thermodynamically less favored by 22.4 and 6.0 kcal mol-1 respectively. It was found that the transition structures for the C-alkylations are imbalanced due to the endoergic rehybridi-zation of the carbon center from sp2 to sp3 which leads to premature bond contraction of the C-Y bond and delayed bond stretching of the C-X bond. In the O-, or S-alkylation, such endoergic process is not required since the σ-lone pair on O or S is involved in the initial stage of alkylation. The imbalanced TSs for the C-alkylation are accompanied by higher intrinsic barriers and deformation energies.

• Korean Journal of Microbiology
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• v.39 no.1
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• pp.16-20
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• 2003

A phylogenetic analysis of bacterial populations inhabiting soil derived from serpentine was conducted. The samples were collected from adjacent metamorphic rocks and serpentinite soil at Kwangcheon. The pH of the serpentine areas ranged from 8.5 to 9.2. The number of bacteria on the DAL medium which was diluted with $10^{-2}$ of AL medium was 10~100 fold higher than that from the full strength of AL medium, and which indicates that oligotrophs are distributed in the serpentinite soil. Of a total of 76 isolates, 42 isolates were oligotrophic bacteria, which grew only on the DAL medium. Based on a phylogenetic analysis using 16S rDNA sequences, these isolates are found to fall within five major phylogenetic groups: proteobacteria $\alpha$-subdivision (3 strains), $\alpha$-subdivision (7 strains), $\gamma$-subdivision (2 trains); high G+C gram-positive bacteria (19 strains); low G+C grampositive bacteria (14 strains). Bacteria of the genus Streptomyces (high G+C division) and Bacillus (low G+C division) have been considered to form a numerically important fraction of serpentinite soil. Oligotrophic strains categorized as Afipia ($\alpha$-subdivision), Ralstonia, Variovorax ($\beta$-subdivision), Pseudomonas ($\gamma$ -subdivision), Arthrobacter (high G+C division), and Streptomyces (low G+C division).

• Journal of Food Hygiene and Safety
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• v.33 no.6
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• pp.495-499
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• 2018

The reduction effect of UV-C irradiation and mild heat treatment was examined against Escherichia coli O157:H7 and Salmonella Typhimurium on black pepper powder. E. coli O157:H7 (ATCC 35150) and S. Typhimurium (ATCC 19585) were inoculated onto black pepper powder at approximately $10^7$ and $10^6CFU/g$, respectively. E. coli O157:H7 and S. Typhimurium were treated with UV-C and mild heat at $60^{\circ}C$. A UV-C intensity ($2.32W/cm^2$ ) was used for 10 min to 70 min at $60^{\circ}C$. After UV-C and heat treatment at $60^{\circ}C$, microbial analysis and color change of black pepper powder was conducted. E. coli O157:H7 and S. Typhimurium were reduced by a level of 1.89 and 2.24 log CFU/g, respectively, when treated with UV-C alone for 70 min. And E. coli O157:H7 and S. Typhimurium were reduced by 2.22 and 5.10 log CFU/g, respectively, when treated with mild heat treatment at $60^{\circ}C$ alone for 70 min. But when combined with UV-C and mild heat, it showed higher levels of reduction by 2.46 and 5.70 log CFU/g. S. Typhimurium was more easily reduced than E. coli O157:H7. Color values were not significantly (p > 0.05) different in all treated samples. Therefore, these results suggest that the combined treatment with UV-C and mild heat was effective to inactivate the food pathogens in black pepper powder and can be used as a food industrial microbial intervention method.