• ALGAE
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• 제29권2호
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• pp.137-152
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• 2014

Mixotrophic protists play diverse roles in marine food webs as predators and prey. Thus, exploring mixotrophy in phototrophic protists has emerged as a critical step in understanding marine food webs and cycling of materials in marine ecosystem. To investigate the feeding of newly described mixotrophic dinoflagellate Ansanella granifera, we explored the feeding mechanism and the different types of species that A. granifera was able to feed on. In addition, we measured the growth and ingestion rates of A. granifera feeding on the prasinophyte Pyramimonas sp., the only algal prey, as a function of prey concentration. A. granifera was able to feed on heterotrophic bacteria and the cyanobacterium Synechococcus sp. However, among the 12 species of algal prey offered, A. granifera ingested only Pyramimonas sp. A. granifera ingested the algal prey cell by engulfment. With increasing mean prey concentration, the growth rate of A. granifera feeding on Pyramimonas sp. increased rapidly, but became saturated at a concentration of $434ngCmL^{-1}$ (10,845 cells $mL^{-1}$). The maximum specific growth rate (i.e., mixotrophic growth) of A. granifera feeding on Pyramimonas sp. was $1.426d^{-1}$, at $20^{\circ}C$ under a 14 : 10 h light-dark cycle of $20{\mu}Em^{-2}s^{-1}$, while the growth rate (i.e., phototrophic growth) under similar light conditions without added prey was $0.391d^{-1}$. With increasing mean prey concentration, the ingestion rate of A. granifera feeding on Pyramimonas sp. increased rapidly, but slightly at the concentrations ${\geq}306ngCmL^{-1}$ (7,649 cells $mL^{-1}$). The maximum ingestion rate of A. granifera feeding on Pyramimonas sp. was 0.97 ng C $predator^{-1}d^{-1}$ (24.3 cells $grazer^{-1}d^{-1}$). The calculated grazing coefficients for A. granifera feeding on co-occurring Pyramimonas sp. were up to $2.78d^{-1}$. The results of the present study suggest that A. granifera can sometimes have a considerable grazing impact on the population of Pyramimonas spp.

• Advances in Energy Research
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• 제2권1호
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• pp.1-9
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• 2014

The green microalgae Chlamydomonas reinhardtti is well-known specie in the terms of $H_2$ production by photo fermentation and has been studying for a long time. Although the $H_2$ production yield is promising; there are some bottlenecks to enhance the yield and efficiency to focus on a well-designed, sustainable production and also scaling up for further studies. D1 protein of photosystem II (PSII) plays an important role in photosystem damage repair and related to $H_2$ production. Because Chlamydomonas is the model algae and the genetic basis is well-studied; metabolic engineering tools are intended to use for enhanced production. Mutations are focused on D1 protein which aims long-lasting hydrogen production by blocking the PSII repair system thus $O_2$ sensitive hydrogenases catalysis hydrogen production for a longer period of time under anaerobic and sulfur deprived conditions. Chlamydomonas CC124 as control strain and D1 mutant strains(D240, D239-40 and D240-41)are cultured photomixotrophically at $80{\mu}mol\;photons\;m^{-2}s^{-1}$, by two sides. Cells are grown in TAP medium as aerobic stage for culture growth; in logarithmic phase cells are transferred from aerobic to an anaerobic and sulfur deprived TAP- S medium and 12 mg/L initial chlorophyll content for $H_2$ production which is monitored by the water columns and later detected by Gas Chromatography. Total produced hydrogen was $82{\pm}10$, $180{\pm}20$, $196{\pm}20$, $290{\pm}30mL$ for CC124, D240, D239-40, D240-41, respectively. $H_2$ production rates for mutant strains was $1.3{\pm}0.5mL/L.h$ meanwhile CC124 showed 2-3 fold lower rate as $0.57{\pm}0.2mL/L.h$. Hydrogen production period was $5{\pm}2days$ for CC124 and mutants showed a longer production time for $9{\pm}2days$. It is seen from the results that $H_2$ productions for mutant strains have a significant effect in terms of productivity, yield and production time.

• 한국자원식물학회지
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• 제21권1호
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• pp.60-65
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• 2008

배발생 캘러스 유도 실험을 통해 음나무의 대량 증식의 가능성을 제시하였다. 절편체의 부위 및 호르몬 농도에 따라 약간의 차이는 보였으나 대부분의 조건에서 배발생 캘러스가 유기되었다. 특히 엽병 절편체에 비하여 잎 절편체에서 배발생 캘러스 유기가 더 활발히 이루어졌으며, 2.0mg/l의 2,4-D와 0.1mg/l의 BA를 혼합 처리한 조건에서 가장 많이 유기됨을 확인할 수 있었다. 배발생 캘러스의 대량 증식을 위하여 현탁배양을 실시한 결과 1.0mg/l의 2,4-D를 첨가한 배양액이 증식에 가장 좋은 것으로 나타났으며, 무기염류를 1/2로 반감한 B5 배지와 White 배지가 적당한 것으로 나타났다. 또한 탄소원은 3%의 농도를 사용하였을 때 캘러스 증식 뿐만 아니라 체세포 배의 발아에도 적당한 것으로 나타났다. 따라서 본 실험 결과는 생물반응기를 이용한 음나무의 대량 생산을 가능하게 하는 기초 자료로 이용될 수 있을 것으로 생각된다.

• Journal of Radiation Protection and Research
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• 제16권2호
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• pp.41-54
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• 1991

라돈 및 붕괴생성물의 호흡에 의한 인체 피폭선량의 제어가능성을 찾기 위해 다음과 같은 과정을 거쳤다. 1) 라돈에 관련된 기존모델을 토양 기공모델, 실내붕괴 모델, 폐선량계산모델로 분류해석하고, 2) topology이론에 따라 물리유추개념으로써 회로망으로 전환하여, 라돈환경계통을 정식화, 검증계산을 거쳐, 3) 모의계산으로 선량감도를 분석하여 최적 매개변수의 범위를 모색하였다. 매개변수인 환기율, 침적율, 부착율가 제어범위내 변화될 때, 정식화된 111원 연립방정식의 해를 구하여 선량감도를 분석하였으며, 제어매개변수의 선량감도에 의한 효과를 3차원으로 도식화하였다. 본 연구 수행결과, 제어매개변수 변화에 따른 실내의 $^{222}Rn$ 및 Rn-D의 농도 변화과정은 새롭게 해석할 수 있는 벡터감도단층모형으로, 일부 제어매개변수의 조합변화에 따른 선량감도는 3차원 그래프모형으로 나타낼 수 있었다. 선량감도의 3차원 그래프에서는 실내환경의 대표적 매개변수 값 범위에서 변곡점이 나타났으며, 일반적으로 높은 환기조건$(>1h^{-1})$하에서는 공기정화에 의하여 선량이 전반적으로 증가되나, 불충분한 환기조건$(<0.5h^{-1})$하에서는 공기정화에 의하여, 선량이 40%정도로 감소되는 것으로 나타났다 (* 라돈 및 붕괴생성물은 이하 $^{222}Rn$ 및 Rn-D로 통일한다.)

• 한국식품영양과학회지
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• 제7권2호
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• pp.43-46
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• 1978

고추과실의 placenta 조직(組織)을 합성배양(合成培養)기에서 배양(培養)코저 callus발생(發生)에 적합(適合)한 배지(培地)를 선택하고 callus의 증식 속도를 검토한 결과 다음의 결과(結果)를 얻었다. callus발생(發生)에는 Linsmaier and Skoog RM 1964 기본 배지에 2, 4-D $(10^{-5}M)$과 kinetin $(10^{-6}M)$을 함유한 고형배지(固形培地)가 가장 효과적(效果的)이었다. 이들 callus는 배양후 2주일부터 3주일 사이에 가장 증식이 빨랐고 그 이후는 완만한 속도를 보였다.

• 한국양식학회지
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• 제11권2호
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• pp.141-149
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• 1998

돌돔의 수정란을 조기에 생산하기 위하여 수온과 광주기 조절에 의한 산란을 유도하였다. 실험 I에서는 12월 15일 수온 14.5$^{\circ}C$에서 2월 22일 $21.0^{\circ}C$로 증가시키고 광주기도 10 : 30 L에서 2월 17일 15 : 30 L로 증가시킨 결과 65일 만에 산란이 시작되었으며 총 산란기간은 40일간 이었다. 총산란량은 3,004.4만개, 부상란 수는 2,454.2만개로 부상률은 85.6%이며, 평균 수정률은 77.2%였다. 실험 II에서는 수온만을 실험 I과 같이 상승시킨 결과 산란이 이루어지지 않아 광주기를 15 ; 30 L로 조절한 지 7일만에 산란이 이루어졌으며, 총 산란기간은 40일, 총산란량은 2,128만개, 부상란수는 1,862만개, 평균 수정률은 72.1%였다.

• 대한기계학회논문집B
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• 제28권10호
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• pp.1139-1146
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• 2004

The effect of triangular tabs attached at the perimeter of jet nozzle on heat transfer enhancement was investigated experimentally. The modified flow structure was visualized using a smoke-wire method. Four different types of jet nozzle having 0, 4, 6 and 8 tabs were tested at jet Reynolds number Re=15,000 to investigate the effect of tabs on the variation of heat transfer rate. The local and average Nusselt numbers are increased with increasing the number of tabs. At nozzle-to-plate distance of L/D=4, the average Nusselt number was increased about 9.9% at Re=15,000 in the impingement region for the case of 8 tabs attachment. As the nozzle-to-plate distance increases, however, the heat transfer enhancement effect of triangular tabs is reduced. For the case of 4 tabs, the heat transfer enhancement is not so distinctive at L/D=8. As the protrusion depth of tabs into the jet flow increases, the heat transfer rate is also enhanced when the nozzle-to-plate distance is smaller than L/D=6.

• KSBB Journal
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• 제27권2호
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• pp.97-102
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• 2012

In the present study, the biomass productivity of two green microalgae (Chlorella sp. and Dunaliella salina DCCBC2) were assessed in a 12 L tubular photobioreactor under optimum culture conditions. In the batch culture optimization process, the Chlorella sp. biomass was obtained as 1.2 g/L under atmospheric air as a sole $CO_2$ source and other culture conditions as follows: light intensity, temperature, pH, $NH_4Cl$ and $K_2HPO_4$ were 100 ${\mu}E/m^2/s$, $27^{\circ}C$, 7.0, 20.0 mM and 2.0 mM, respectively. On the other hand, 2.9 g/L of D. salina DCCBC2 biomass production was observed under the following conditions: light intensity, temperature, pH, $KNO_3$ and $K_2HPO_4$were 80 ${\mu}E/m^2/s$, $27^{\circ}C$, 8.0, 3.0 mM and 0.025 mM, respectively. At 1% $CO_2$ supply to the reactor, the Chlorella sp. production was reached 1.53 g/L with 25% increment under the same operating conditions. In addition, the maximum D. salina DCCBC2 biomass was observed as 3.40 g/L at 3% $CO_2$ concentration. Based on the aforementioned optimized conditions, the dilution rate and maximal biomass productivity of Chlorella sp. and D. salina DCCBC2 in the continuous cultivation were 0.4/d and 0.6 g/L/d and 0.6/d and 1.5 g/L/d, respectively.

• Asian-Australasian Journal of Animal Sciences
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• 제16권2호
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• pp.185-188
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• 2003

Data on the use of breeding records of dairy cattle farm of Fenghuang-shan in Chengdu areas during a period of six years is systematically analyzed. The results show that Holstein heifers have their 1st estrus at an average age of $513.6{\pm}46.7$ d which is not related to the calving season. Estrus mostly occurs in the months with mild ambient temperature (March, April, May, November and December). There is a very poor rate of estrus detection; only 30.0% successive estrus is observed within 24 d, 29.3% within 25-48 d, 40.6% over 48 d. The average number of insemination per conception is 1.50 for heifers and 1.74 for cows, but conception rate (CR) is lower in the relatively warm months (July, August and September) ranged from 48.1% to 51.9% compared with 58.1% to 68.5% in other months. High temperature is the most important factor affecting fertilization in warm months, but neither did CR decline immediately with the increased air temperature in June, nor did it increase immediately with the declined air temperature in September. Post partum anestrous period is $119.5{\pm}60.5$ d. The average interval from calving to conception is $159.4{\pm}85.6$ d with only 19.8% of the cows conceived within 85 d of calving. Cows with high milk yield have longer acyclic periods and lower conception rates. Improvement of efficient managements must be a precedent condition in Chengdu areas.

• Journal of Microbiology and Biotechnology
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• 제9권6호
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• pp.716-721
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• 1999

It has been known that continuous cultivation of hairy root is difficult to maintain for a long period of time compared to the microbial and callus cultures. Chemostat cultivation was successfully carried out in order to economically produce a plant-based colorant, betacyanin, from red beet hairy root for more than 85 days in a 14-1 fermentor. The result from the chemostat cultivation was compared to those of the batch and fed-batch cultivations of red beet hairy roots. It was shown that hairy root reached its steady state within 50 days of the cultivation, and then maintained for about 25-30 days in a wide range of dilution rates. Total betacyanin production from the continuous process was also calculated to be 2.65g at 0.28(l/d) of dilution rate, compared to 0.196g from fed-batch cultivation. It was found that betacyanin production was a partially growth related process, yielding 0.376 mg/g-fresh wt. cell and $1.89{\times}10^{-5}$ mg/g-fresh wt. cell/d, with 0.92 of correlation factor in a partial growth-product model. It was also shown that the cell growth required was relatively large for maintenance amount of energy at a low dilution rate. The growth of hairy root was inhibited by high light intensity in following a photo-inhibition model. The growth parameters were estimated to be 0.3(l/d), $10.56kcal/\textrm{m}^2/h$,{\;}and{\;}35.81kcal/\textrm{m}^2/h$ for the maximum specific growth rate, half saturation light intensity, and inhibition light intensity, respectively.