• 분석과학
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• 제35권4호
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• pp.181-188
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• 2022

This paper describes a comparative analysis of yeast cell viability at exponential and stationary growth phases using multiple conventional techniques and statistical tools. Overall, cellular responses to various viability assays were asynchronous. Results of optical density measurement and direct cell counting were asynchronous both at exponential and stationary phases. Proliferative capacity measurement using SP-SDS indicated that cells at the end of the stationary phase were proliferative as much as exponentially growing cells. Metabolic activity assays using two different dyes concluded that the inside of cells at stationary phase is slightly less reducing compared to that of exponentially growing cells, implying that the metabolic activity imperceptibly declined as cells were aged. These results will be helpful to understand the details of yeast cell viability at exponential and stationary growth phases.

• 한국광물학회지
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• 제18권4호통권46호
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• pp.237-248
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• 2005

[ $Mg_{2}SiO_{4}{-}$ ]스피넬에서 올리빈으로의 역상변이에 대한 고온 X-선 회절실험 결과, 진공상태에서 가열하였을 때 상변이가 일어나며, 일정한 온도에서 스피넬상으로부터 올리빈상이 시간이 경과하면서 성장하는 것으로 보아 상변이 메커니즘은 '핵생성 및 성장' 형태인 것으로 판단된다. 스피넬 상으로부터 올리빈 상으로 역상변이 할 때의 활성화 에너지를 구하기 위해 $Mg_{2}SiO_{4}{-}$스피넬 시료에 대한 상변이 실험을 진공 및 고온($1023\∼1116\;k$)에서 시행하였다. 올리빈 상에 대해 '주어진 시간에 따른 비분율법'을 이용하여 활성화 에너지 값을 결정하였다. 아브라미 방정식을 이용하여 계산한 결과, n값은 대체로 온도가 증가함에 따라 매우 넓은 영역에서 동반 상승하는데, 이러한 현상은 '핵생성 및 성장' 메커니즘이 아마도 온도에 종속적이지 않느냐 하는 것을 제시해주고 있다. 상대적으로 낮은 온도에서는 $Mg_{2}SiO_{4}{-}$스피넬은 핵이 생성된 자리가 포화된 후, 새로운 결정상이 표면에서 성장을 시작하고 시간이 지남에 따라 내부 쪽으로 옮아가는 것으로 판단된다. 그러나 고온에서, 성장은 핵이 생성된 자리가 포화되고 난 후 표면뿐만 아니라, 내부에서도 동시에 시작되는 것으로 보인다.

• Journal of Animal Science and Technology
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• 제58권11호
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• pp.39.1-39.12
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• 2016

Background: The current study investigates the anti-stress effects of clove (Eugenia caryophyllus) extracts (0, 200, 400, and 600 mg/kg) on serum antioxidant biomarkers, immune response, immunological organ growth index, and expression levels of acute phase proteins (APPs); ovotransferrin (OVT), ceruloplasmin (CP), ceruloplasmin (AGP), C-reactive protein (CRP), and serum amyloid-A (SAA) mRNA in the immunological organs of 63-d-old male black-meated Silkie fowls subjected to 21 d chronic heat stress at $35{\pm}2^{\circ}C$. Results: The results demonstrated that clove extract supplementation in the diet of Silkie fowls subjected to elevated temperature (ET) improve growth performance, immune responses, and suppressed the activities of glutathion peroxidase (GSH-Px), superoxide dismutase (SOD), catalase (CAT), and thioredoxin reductase (TXNRD); reduced serum malonaldehyde (MDA) and glutathione (GSH) concentrations when compared with fowls raised under thermoneutral condition (TC). Upon chronic heat stress and supplementation of clove extracts, the Silkie fowls showed a linear increase in GSH-Px, SOD, CAT, and TXNRD activities (P = 0.01) compared with fowls fed diets without clove extract. ET decreased (P < 0.05) the growth index of the liver, spleen, bursa of Fabricius and thymus. However, the growth index of the liver, spleen, bursa of Fabricius and thymus increased significantly (P < 0.05) which corresponded to an increase in clove supplemented levels. The expression of OVT, CP, AGP, CRP, and SAA mRNA in the liver, spleen, bursa of Fabricius and thymus were elevated (P < 0.01) by ET compared with those maintained at TC. Nevertheless, clove mitigates heat stress-induced overexpression of OVT, CP, AGP, CRP and SAA mRNA in the immune organs of fowls fed 400 mg clove/kg compared to other groups. Conclusions: The results showed that clove extracts supplementation decreased oxidative stress in the heat-stressed black-meated fowls by alleviating negative effects of heat stress via improvement in growth performance, antioxidant defense mechanisms, immunity, and regulate the expression of acute phase genes in the liver and immunological organs.

• Asian-Australasian Journal of Animal Sciences
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• 제29권7호
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• pp.979-986
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• 2016

This experiment was conducted to investigate the effects of dried mealworm (Tenebrio molitor larva) on growth performance, nutrient digestibility and blood profiles in weaning pigs. A total of 120 weaning pigs ($28{\pm}3days$ and $8.04{\pm}0.08kg$ of body weight) were allotted to one of five treatments, based on sex and body weight, in 6 replicates with 4 pigs per pen by a randomized complete block design. Supplementation level of dried mealworm was 0%, 1.5%, 3.0%, 4.5%, or 6.0% in experimental diet as treatment. Two phase feeding programs (phase I from 0 day to 14 day, phase II from 14 day to 35 day) were used in this experiment. All animals were allowed to access diet and water ad libitum. During phase I, increasing level of dried mealworm in diet linearly improved the body weight (p<0.01), average daily gain (ADG) (p<0.01) and average daily feed intake (ADFI) (p<0.01). During phase II, ADG also tended to increase linearly when pigs were fed higher level of dried mealworm (p = 0.08). In addition, increasing level of dried mealworm improved the ADG (p<0.01), ADFI (p<0.05) and tended to increase gain to feed ratio (p = 0.07) during the whole experimental period. As dried mealworm level was increased, nitrogen retention and digestibility of dry matter as well as crude protein were linearly increased (p = 0.05). In the results of blood profiles, decrease of blood urea nitrogen (linear, p = 0.05) and increase of insulin-like growth factor (linear, p = 0.03) were observed as dried mealworm was increased in diet during phase II. However, there were no significant differences in immunoglobulin A (IgA) and IgG concentration by addition of dried mealworm in the growth trial. Consequently, supplementation of dried mealworm up to 6% in weaning pigs' diet improves growth performance and nutrient digestibility without any detrimental effect on immune responses.

• Journal of Microbiology and Biotechnology
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• 제1권4호
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• pp.274-280
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• 1991

Effects of IPTG induction on cell growth and production of ${\beta}$-galactosidase-preS2 fusion protein (${\beta}$gal-preS2) were studied in a defined medium using a recombinant Escherichia coli JM109/pCMHB30. IPTG was added (0.2 mM) to induce the cloned-gene expression in the early-, mid-, and late-log growth phases. The most serious decreases in growth rate and plasmid stability were observed for the induction in the early-log growth phase. The expression level of ${\beta}$gal-preS2 attained by the induction in the mid-log phase was about 0.51 mg fusion protein/mg total cellular protein, which was 2- and 5-fold improvement over the levels obtained with the inductions in the early- and late-log phases. Formation of acidic byproducts including acetate and pyruvate showed different profiles during the fermentation period for each cases of induction; pyruvate was the major byproduct for the induction in the early-log phase while acetate production became more significant for the cases of inductions in the mid- and late-log phases.

• 한국세라믹학회지
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• 제47권6호
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• pp.485-490
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• 2010

In our previous studies, continuous SiC fiber-reinforced SiC-matrix composites ($SiC_f$/SiC) had been fabricated by two different slurry infiltration methods: vacuum infiltration and electrophoretic deposition (EPD). 12 wt% of $Al_2O_3-Y_2O_3$-MgO with respect to SiC powder was used as additives for liquid-phase assisted sintering. After hot pressing at $1750^{\circ}C$ under 20 MPa for 2 h in Ar atmosphere, a high composite density could be achieved for both cases, whereas the problems such as large grain size and non-uniform distribution of liquid phase were observed, which was resulted in the relatively poor mechanical properties of composites. Therefore, efforts have been made to reduce the grain growth during the sintering, including the optimization for hot pressing condition and utilization of spark plasma sintering using a SiC monolith. Based on the results, spark plasma sintering was found to be effective method in decreasing the amount of sintering additive, time and grain growth, which will be explained in comparison to the results of hot pressing in this paper.

• 한국컴퓨터산업학회논문지
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• 제3권7호
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• pp.837-844
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• 2002

소프트웨어 개발 과정에서 시스템 내에 잔존하는 결함을 발견하거나 수정하기 위해 테스트를 실시한다. 테스트 단계에서 결함을 발견하고 소프트웨어 신뢰성을 평가할 수 있다. 수리적으로 신뢰성을 평가할 수 있는 모델이 소프트웨어 신뢰도 성장 모델이다. 이 모델의 대부분은 결함의 형태가 하나이고 결함율은 일정하다라는 가정에서 진행되고 있다. 본 연구에서는 테스트 단계에서 발견되는 결함이 일정하지 않다라는 관점에서 새로운 모델을 제안하고 결함 데이터를 적용해보았다. 또한 기존의 모델과 비교 및 분석하여 타당성을 증명하였다.

• Molecules and Cells
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• 제21권1호
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• pp.82-88
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• 2006

The global pattern of growth-dependent gene expression in Streptococcus pneumoniae strains was evaluated using a high-density DNA microarray. Total RNAs obtained from an avirulent S. pneumoniae strain R6 and a virulent strain AMC96-6 were used to compare the expression patterns at seven time points (2.5, 3.5, 4.5, 5.5, 6.0, 6.5, and 8.0 h). The expression profile of strain R6 changed between log and stationary growth (the Log-Stat switch). There were clear differences between the growth-dependent gene expression profiles of the virulent and avirulent pneumococcal strains in 367 of 1,112 genes. Transcripts of genes associated with bacterial competence and capsular polysaccharide formation, as well as clpP and cbpA, were higher in the virulent strain. Our data suggest that late log or early stationary phase may be the most virulent phase of S. pneumoniae.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 2000년도 Proceedings of 2000 International Nano Crystals/Ceramics Forum and International Symposium on Intermaterials
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• pp.243-248
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• 2000

Effect of NiO addition on microstructure, stability of tetragonal phase and mechanical properties was investigated. (Y, Ni)-TZP solid solution was obtained by pressureless sintering. The fracture toughness was increased by solid solution of NiO. Neither reaction phase nor glassy phase was observed at the grain boundaries. From these results, it was determined that solid solution of NiO was destabilized tetragonal phase of Y-TZP. Y-TZP/Ni nanocomposite that contained nano-sized Ni particles was also fabricated by internal reduction method. Some evaluations and discussions were carried out for both (Y, Ni)-TZP solid solution and Y-TZP/Ni nanocomposite.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1997년도 Proceedings of the 12th KACG Technical Meeting and the 4th Korea-Japan EMGS (Electronic Materials Growth Symposium)
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• pp.79-85
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• 1997

Fe$_2$O$_3$ thin films were prepared on $Al_2$O$_3$ substrate by PECVD(Plasma-Enhanced Chemical Vapor Deposition) process. The phase transformation of iron oxide film was determined as the substrate temperature and reduction-oxidation process. $\alpha$-Fe$_2$O$_3$ was stable in deposition temperature ranges of 80~15$0^{\circ}C$. Fe$_3$O$_4$ phase was obtained by the reduction process of $\alpha$-Fe$_2$O$_3$ phase in H$_2$ ambient. Fe$_3$O$_4$ phase was transformed into a ${\gamma}$-Fe$_2$O$_3$ thin film under controlled oxidation conditions at 280~30$0^{\circ}C$.