• 제목/요약/키워드: relative growth

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Growth Modelling of Listeria monocytogenes in Korean Pork Bulgogi Stored at Isothermal Conditions

  • Lee, Na-Kyoung;Ahn, Sin Hye;Lee, Joo-Yeon;Paik, Hyun-Dong
    • 한국축산식품학회지
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    • 제35권1호
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    • pp.108-113
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    • 2015
  • The purpose of this study was to develop predictive models for the growth of Listeria monocytogenes in pork Bulgogi at various storage temperatures. A two-strain mixture of L. monocytogenes (ATCC 15313 and isolated from pork Bulgogi) was inoculated on pork Bulgogi at 3 Log CFU/g. L. monocytogenes strains were enumerated using general plating method on Listeria selective medium. The inoculated samples were stored at 5, 15, and $25^{\circ}C$ for primary models. Primary models were developed using the Baranyi model equations, and the maximum specific growth rate was shown to be dependent on storage temperature. A secondary model of growth rate as a function of storage temperature was also developed. As the storage temperature increased, the lag time (LT) values decreased dramatically and the specific growth rate of L. monocytogenes increased. The mathematically predicted growth parameters were evaluated based on the modified bias factor ($B_f$), accuracy factor ($A_f$), root mean square error (RMSE), coefficient of determination ($R^2$), and relative errors (RE). These values indicated that the developed models were reliably able to predict the growth of L. monocytogenes in pork Bulgogi. Hence, the predictive models may be used to assess microbiological hygiene in the meat supply chain as a function of storage temperature.

쇠미역사촌과 미역 포자체의 배양 및 야외 개체군의 생장 비교 (Comparison on the Growth of Costaria costata and Undaria pinnatifida Sporophytes in Culture and Their Field Populations)

  • 박서경;허진석;김보연;송지나;임거영;김하니;최한길
    • 한국수산과학회지
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    • 제44권1호
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    • pp.71-77
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    • 2011
  • The effects of temperature, light, and salinity on the growth of Costaria costata and Undaria pinnatifida juveniles were examined in laboratory cultures. In a cultivation farm, the monthly yield and density were also investigated between December and April for C. costata and between December and March in 2007 and 2008 for U. pinnatifida. The relative growth rates (RGRs) were greater at $20{\sim}60\;{\mu}mol$ photons $m^{-2}s^{-1}$ than at low ($0{\sim}10\;{\mu}mol$ photons $m^{-2}s^{-1}$) and high ($100{\sim}180\;{\mu}mol$ photons $m^{-2}s^{-1}$) irradiance levels. The optimal growth conditions for the two species were $17^{\circ}C$, 35 psu, $60\;{\mu}mol$ photons $m^{-2}s^{-1}$, and a daylength of 12 h, indicating that C. costata and U. pinnatifida have very similar growth responses to temperature, light, and salinity. However, the growth responses of the two species to various environmental factors were different; C. costata grew faster than U. pinnatifida but the latter species grew well at low salinity. The monthly yield of C. costata and U. pinnatifida increased steadily over the study period, and it was maximal in March for both species, but the yield of U. pinnatifida was greater than that of C. costata.

가압부상 후 잔류 응집제가 플랑크톤 군집에 미치는 영향 (The Effects of Residual Al on Plankton Community after Dissolved Air Flotation (DAF) Application)

  • 김호섭;공동수;이형진;신종규;강태구
    • 한국물환경학회지
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    • 제23권6호
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    • pp.837-842
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    • 2007
  • This study was conducted to test the effect of residual Al on plankton community after dissolved air flotation (DAF) application. Growth rate of phytoplankton after DAF application ($0.37day^{-1}$) was about 2 times lower than that before DAF application ($0.70day^{-1}$). Under the condition of addition of nitrogen and phosphorus without light, growth rate phytoplankton in treatment without residual Al increased in difference with showing the negative growth rate in treatment with residual Al. Under the condition of light without addition of nutrient, growth rate of phytoplankton was no noticeable difference between the before and after DAF application. The relatively high settling rate (0.47 m/day) was observed in treatment after DAF application. Although the abundance of rotifer decreased, the abundance of copepod and cladoceran such as Daphnia galeata, Diaphanosoma sp. and Bosmina longirostris with relative higher grazing was no noticeable difference between the before and after DAF application. In the treatments before and after DAF application with zooplankton, growth rate of phytoplankton was $0.41{\pm}0.08day^{-1}$, $0.20{\pm}0.03day^{-1}$, respectively. This difference was in treatment after DAF application similar with those in treatments before and after DAF application without zooplankton. Those indicate that the filter-feeding effect of zooplankton on phytoplankton community may be not changed by residual Al after the DAF application. These results suggest that residual Al after DAF application be to improve water quality by inhibition of growth rate as well as increasing settling rate of phytoplankton.

Growth behavior on initial layer of ZnO:P layers grown by magnetron sputtering with controlled by $O_2$ partial pressure

  • 김영이;안철현;배영숙;김동찬;조형균
    • 한국재료학회:학술대회논문집
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    • 한국재료학회 2009년도 춘계학술발표대회
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    • pp.28.1-28.1
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    • 2009
  • The superior properties of ZnO such as high exciton binding energy, high thermal and chemical stability, low growth temperature and possibility of wet etching process in ZnO have great interest for applications ranging from optoelectronics to chemical sensor. Particularly, vertically well-aligned ZnO nanorods on large areas with good optical and structural properties are of special interest for the fabrication of electronic and optical nanodevices. Currently, low-dimensional ZnO is synthesized by metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), thermal evaporation, and sol.gel growth. Recently, our group has been reported about achievement the growth of Ga-doped ZnO nanorods using ZnO seed layer on p-type Si substrate by RF magnetron sputtering system at high rf power and high growth temperature. However, the crystallinity of nanorods deteriorates due to lattice mismatch between nanorods and Si substrate. Also, in the growth of oxide using sputtering, the oxygen flow ratio relative to argon gas flow is an important growth parameter and significantly affects the structural properties. In this study, Phosphorus (P) doped ZnO nanorods were grown on c-sapphire substrates without seed layer by radio frequency magnetron sputtering with various argon/oxygen gas ratios. The layer change films into nanorods with decreasing oxygen partial pressure. The diameter and length of vertically well-aligned on the c-sapphire substrate are in the range of 51-103 nm and about 725 nm, respectively. The photoluminescence spectra of the nanorods are dominated by intense near band-edge emission with weak deep-level emission.

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보리 유식물에 처리한 수은의 분포 및 독성 연구 (Toxic Effects and Distribution of Mercury in Barley Seedlings)

  • 이춘환;장호식
    • 한국환경과학회지
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    • 제1권1호
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    • pp.13-21
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    • 1992
  • The inhibitory effects of mercury ions on the growth of barley seedlings were studied and the distribution of metal elements in the organs of treated plants was investigated by using synchrotron radiation induced X-ray emission (SRIXE). Although the treatment of mercury ions caused growth inhibition, the mercury-specific increase in variable fluorescence and the abolishment of energy-dependent quenching in broken barley chloroplasts as shown by Moon et at. (1992) were not observed in the leaves of growth-inhibited seedlings. Instead the treatment of mercury decreased Fmax and Fo values. However, Fmax/Fo ratio and photochemical and nonphotochemical quenching coefficients were not affected significantly. By SRIXE analysis of $10\mu\textrm{m}$ mercury chloride treated seedlings, accumulation of mercury in roots was observed after 1 hour of treatment and similar concentration was sustained for 48 hours. Relative contents of mercury was high in roots and underground nodes where seeds were attachedl but was very low in leaves. Iron and zinc were also distributed mainly in the lower parts of the seedlings. However after 72 hours of treatment the contents of these metals in roots decreased and their distribution became more uniform, which may lead to death of the plants. These results suggest that the observed inhibitory effects on barley seedlings upto 48 hours after the treatment is not due to direct damages in the photosynthetic apparatus, but due to its accumulation in roots and the consequent retardation of the growth of barley seedlings. The decrease in Fmax and Fo is probably due to the decrease in chlorophyll and protein contents caused by the retardation of growth. The observed slow expansion of primary leaves could be also explained by the retardation of growth, but the fluorescence induction pattern from the leaves did not show characteristic symptoms of leaves under water stress.

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Artificial cultivation of Medicinal Mushroom, Phellinus linteus using Mulberry logs

  • Hong, In-Pyo;Sung, Gyoo-Byung;Chung, In-Mo;Lee, Won-Chu
    • 한국잠사곤충학회지
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    • 제44권2호
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    • pp.74-81
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    • 2002
  • The optimal conditions for mycelial growth of P. linteus ASI 26011 were 25-30$^{\circ}C$ and pH 6.0, respectively. The mycelial growth of P. linteus was excellent on MCM medium. In case of carbon sources, the mycelial growth of P. linteus was best on the culture media that were contained with sucrose, mannose and glucose. Potassium nitrate and sodium nitrate were good for the mycelial growth of P. linteus as a nitrogen source. For comparison of the mycelial colonization of P. linteus on logs, several techniques of inoculation were tested; the sterilized short log inoculation, drilling inoculation and log-end sandwich inoculation. The mycelial colonization of P. linteus on logs was good in the treatment of sterilized short log inoculation, but poor in the traditional methods such as drilling inoculation and log-end sandwich. The initial mycelial growth and the full mycelial colonization of P. linteus were the best on 20 cm logs under the condition of 42% of moisture content in log. Also the initial mycelial growth of P. linteus was accelerated over 12 hours of sterilization. Burying method of logs after 5-6 months of incubation was the best for formation of basidiocarp of P. linteus. The formation of fruiting body of P. linteus was quite good in the cultivation house at the 31-35$^{\circ}C$ and over 96% of relative humidity.

중국경제의 성장요인과 성장요인별 기여도에 관한 실증연구 (An Empirical Study on the Determinants of Economic Growth and Contribution in China)

  • 김종섭
    • 국제지역연구
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    • 제15권2호
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    • pp.151-173
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    • 2011
  • 본 연구의 목적은 1979년부터 2008년까지 30년 기간 동안 중국에 있어서 경제성장에 영향을 미치는 중요 요소와 요소별 기여수준을 파악하기 위한 것이다. 이를 위하여 고정효과모형과 확률효과모형을 활용하였으며, 적합모델을 선택하기 위하여 Hausman 검정을 활용하였다. 본 연구의 결과 지역금융변수(rsav)가 6개 모형에서 그리고 사회간접자본변수(rsoc)가 2개 모형에서 경제성장에 대해 부(-)의 관계를 보였으나 나머지 3개 변수는 전 모델에서 경제성장에 대해 정(+)의 관계를 보이고 있는 것으로 나타나고 있다. 그리고 노동력 변수의 영향은 서부지역과 동북지역의 경우를 제외하고는 기여율이 상당히 낮은 것으로 파악되었다. 본 연구는 중국의 1인당경제성장률에 대한 각 성장요인의 의미를 찾았는데, 전국모형의 경우 자본의 기여율이 35.9%로 나타난 반면 노동기여율은 4.7% 수준에 불과한 것으로 분석되었다. 그리고 모든 모형에서 자본(rcap)이 중국경제 성장에서 가장 중요한 요인으로 입증되었다.

Salicylic Acid Counteracts Aluminum Stress-induced Growth and Biomass Yield Reduction in Medicago sativa L.

  • Rahman, Md. Atikur;Lee, Sang-Hoon;Song, Yowook;Ji, Hee Jung;Kim, Ki-Yong;Choi, Gi Jun;Lee, Ki-Won
    • 한국초지조사료학회지
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    • 제39권3호
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    • pp.153-157
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    • 2019
  • Salicylic acid (SA) is an essential plant growth regulator that functions as a signaling molecule in plants. The purpose of this study was to clarify how the exogenous application of SA counteracts aluminum stress-induced growth and biomass yield reduction in alfalfa exposed to aluminum (Al) stress. Two-week-old alfalfa seedlings were exposed to a combination of $AlCl_3$ ($0{\mu}M$, $50{\mu}M$ and $100{\mu}M$, respectively) and SA (0.1 mM) for 72 hours. We observed, Al stress-induced plant growth inhibition and forage yield reduction are Al stress-dependent manner. A significant reduction of plant height (42.0-52.9%), leaf relative water content (13.0-21.4%), root length (35.4-48.7%), shoot fresh weight (31.2-25.9%), root fresh weight (15.4-23.3%), shoot dry weight (12.7-22.2%), roots dry weight (47.3-53.5%), were observed in alfalfa. In contrast, SA alleviated the Al-stress and enhanced growth and biomass yield in alfalfa. This study provides useful information concerning the role of SA that counteracts aluminum stress-induced growth and yield reduction in alfalfa.

Effect of substratum types on the growth of assimilators and stolons of Caulerpa okamurae (Bryopsidales, Chlorophyta)

  • Seo Kyoung, Park;Jang K., Kim;Han Gil, Choi
    • ALGAE
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    • 제37권4호
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    • pp.293-299
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    • 2022
  • To examine the effects of substratum types on the growth of Caulerpa okamurae, sand surface and sand burial experiments were conducted. Five assimilators (erect fronds) per replicate were cultured for 15 d on the surface of three different treatments: fine sand (200 ㎛), coarse sand (600 ㎛), and no sand (control). Also, three stolons and three assimilators were buried by fine grain or coarse grain sands and incubated for 15 d. In both experiments, other culture conditions included 25℃, 30 μmol photons m-2 s-1, and 16 : 8 h L : D (light : dark). In both experiments, stolon + assimilator-, assimilator-, and stolon-weights were measured. Relative growth rates (RGRs) of stolon + assimilator weights ranged from 0.43 to 1.95% d-1 at no sand and fine sand treatment, respectively. RGRs for the weight of stolon + assimilator and new assimilators were significantly greater on the fine- and coarse sand surface than the control. In the burial experiments, RGRs of stolons (4.28% d-1 at coarse sand and 5.57% d-1 at fine sand, respectively) were significantly greater than those of assimilators (1.38% d-1 at fine sand and 1.82% d-1 at coarse sand, respectively). When stolons were buried, RGRs for assimilators were greater at the fine sand than at the coarse sand treatment. On the other hand, RGRs of buried assimilators for total frond weights and for newly produced stolons were significantly greater at the coarse sands than at the fine sands. In conclusion, C. okamurae grew well with all substrates of sands and showed better growth on fine sands than coarse ones. This result suggests that the growth of stolons and assimilators of C. okamurae is stimulated after stable attachment to the sand substrates by rhizophores. In addition, stolons showed higher growth rates than the assimilators in the sand burial states, indicating that stolons are more tolerant to low light than assimilators of C. okamurae.

Determination of optimal dietary valine concentrations for improved growth performance and innate immunity of juvenile Pacific white shrimp Penaeus vannamei

  • Daehyun Ko;Chorong Lee;Kyeong-Jun Lee
    • Fisheries and Aquatic Sciences
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    • 제27권3호
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    • pp.171-179
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    • 2024
  • A study was conducted to evaluate dietary valine (Val) requirement for Pacific white shrimp (Penaeus vannamei). Five isonitrogenous (353 g/kg) and isocaloric (4.08 kcal/g) semi-purified diets containing graded levels of Val (2.7, 5.1, 8.7, 12.1 or 16.0 g/kg) were formulated. Quadruplicate groups of 12 shrimp (average body weight: 0.46 ± 0.00 g) were fed one of the experimental diets (2%-5% of total body weight) for 8 weeks. Maximum weight gain was observed in 8.7 g/kg Val group. However, the growth performance was reduced when Val concentration in diets were higher than 12.1 g/kg. Feed conversion ratio was significantly increased with 2.7 and 16.0 g/kg Val inclusion. Shrimp fed the diets containing 2.7 g/kg Val showed significantly lower protein efficiency ratio, whole-body crude protein and Val concentrations. Dietary inclusion of Val significantly improved the relative expression of insulin-like growth factor binding protein and immune-related genes (prophenoloxidase, lysozyme and crustin) in the hepatopancreas and 8.7 g/kg Val group showed highest expression among all the groups. The dietary requirement of Val for maximum growth of juvenile P. vannamei, estimated using polynomial regression analysis on growth, was 9.54 g/kg of Val (27.2 g/kg based on protein level) and maximum growth occurred at 9.27 g/kg of Val (26.2 g/kg based on protein level) based on broken-line regression analysis.