• Biotechnology and Bioprocess Engineering:BBE
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• 제10권3호
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• pp.284-288
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• 2005

Baker's yeast was disrupted in a 1.4-L stainless steel horizontal bead mill under a continuous recycle mode using 0.3 mm diameter zirconia beads as abrasive. A single pass in continuous mode bead mill operation liberates half of the maximally released protein. The maximum total protein release can only be achieved after passaging the cells 5 times through the disruption chamber. The degree of cell disruption was increased with the increase in feeding rate, but the total protein release was highest at the middle range of feeding rate (45 L/h). The total protein release was increased with an increase in biomass concentration from 10 to $50\%$(w/v). However, higher heat dissipation as a result of high viscosity of concentrated biomass led to the denaturation of labile protein such as glucose 6-phosphate dehydrogenase (G6PDH). As a result the highest specific activity of G6PDH was achieved at biomass concentration of $20\%$(ww/v). Generally, the degree of cell disruption and total protein released were increased with an increase in impeller tip speed, but the specific activity of G6PDH was decreased substantially at higher impeller tip speed (14 m/s). Both the degree of cell disruption and total protein release increased, as the bead loading increased from 75 to $85\% (v/v)$. Hence, in order to obtain a higher yield of labile protein such as G6PDH, the yeast cell should not be disrupted at biomass concentration and impeller tip speed higher than $20\%(w/v)$ and 10 m/s, respectively.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2005년도 국제학술대회
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• pp.73-83
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• 2005

Higher methylmercury (MeHg) accumulation and susceptibility to toxicity in the fetus than in the mother at parturition is well known. However, the difference in MeHg exposure to fetus and offspring throughout gestation and suckling is not well established. In the human, the effects of MeHg exposure on pregnant and breast-feeding women remain an important issue for elucidation, especially those of continuous uptake in high-fish-consumption populations. The purpose of this paper was to evaluate the difference in MeHg exposure to fetus and offspring throughout gestation and lactation using our recent animal and human studies data. In the animal study, adult female rats were given a diet containing 5 ${\mu}$g/g Hg (as MeHg) for 8 weeks. Then they were mated and subsequently given the same diet throughout gestation and suckling. On embryonic days 18, 20, 22 and at parturition, the concentrations of Hg in the brains of fetus were approximately 1.5-2.0 times higher than those in the mothers. However, during the suckling period Hg concentrations in the brain rapidly declined to about 1/10 of that during late pregnancy. Hg concentrations in blood also decreased rapidly after birth. In human study, Hg concentrations in red blood cells (RBCs-Hg) in 16 pairs of maternal and umbilical cord blood samples were compared at birth and 3 months of age after parturition. RBCs-Hg concentration in the umbilical cords was about 1.6 times higher than those in the mothers at parturition. However, all the infants showed declines in Hg concentrations throughout the breast-feeding period. The Hg concentration in RBCs-Hg at 3 months of age was about half that at birth. Both the animal and human studies indicated that MeHg exposure to the fetus might be especially high but it dramatically decreases during the suckling period. Therefore, close attention should be paid to the gestation rather than the breast-feeding period to avoid the risk of MeHg to human infants.

• 한국해양학회지
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• 제27권1호
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• pp.11-18
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• 1992

요각들은 Calanus sinicus와 Acartia clausi(A. omorii)의 먹이섭취 양상을 파악 하기 위하여 식물 플랑크톤의 농도변화와 시간경과에 따른 먹이섭취율 및 여과율의 변 화를 실험실에서 조사하였다. 두종의 요각류들의 여과율은 먹이농도가 증가에 따라서 감소했으며, 평균 여과율은 C. sinicus가 2.42 ml/copepod/hr,이고, A. clausi가 3.37 ml/copepod/hr. 이였다. 먹이섭취율은 먹이농도의 증가에 따라 다소 변동은 있지만 수 평적으로 일정하게 유지되는 경향을 보였다. 시간에 따른 요각류들의 여과율은 주기성 을 보이지 않고 전반적으로 감소하는 경향을 보였으나 A. clausi 는 어떤 시간의 경과 후 증가하는 경향을 보였다. 결과적으로 신물플랑크톤의 농도변화에 따른 요각류의 먹 이섭취율과 여과율의 경향은 유사하게 나타났지만, 측정된 값들은 다소 차이를 보였 다. 그리고 시간경과에 따른 조사에서 두종의 요각류들은 불연속적인 포식활동을 전개 하는 것으로 나타났다.

• Asian-Australasian Journal of Animal Sciences
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• 제13권10호
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• pp.1394-1398
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• 2000

This experiment was carried out to examine the seasonal changes in feed intake and feeding behavior in Korean spotted deer under farmed condition to obtain basic information for efficient feeding management. The seasonal daily gain was the highest (p<0.05) in summer and the lowest (p<0.05) in winter. Dry matter intake (DMI) was the highest (p<0.05) in spring (2,685 g/day) and the lowest in winter (1,929 g/day). Intake of roughage in the DMI was the greatest in spring and that in winter was significantly lower (p<0.05) than in spring. Also DMI, expressed in terms of metabolic body weight ($kgW^{0.75}$), was 85.5 g, 70.6 g, 70.9 g and 65.1 g for spring, summer, autumn and winter, respectively, and thus was the highest in spring and the lowest in winter (p<0.05). Deer exhibited similar eating patterns, comparatively short and frequent periods, in all seasons. They showed comparatively intensive patterns of rumination during midnight for autumn and winter and relatively continuous patterns of chewing activity during spring and summer. There were no significant differences in seasonal eating time and ruminating time. However, exercise time was the greatest for winter and the lowest for summer and there was a significant difference (p<0.05) between summer and winter. Although not significant, eating time per 100 gDM ingested tended to be short in spring and summer and long in autumn and winter. Ruminating time per 100 gDM ingested was the shortest (p<0.05) in spring compared with in other seasons. The conclusion can be drawn that since deer have seasonal differences in feed intake and feeding habits, it is necessary to establish and develop an efficient feeding system for deer.

• Journal of Biosystems Engineering
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• 제39권4호
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• pp.366-376
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• 2014

Purpose: In the process of anaerobic digestion, stirring of the digester and feeding of organic waste into the digester have been considered important factors for digestive efficiency. The objective of this study was to determine the most appropriate conditions for both stirring interval of the digester and organic feeding frequency in order to improve anaerobic digestion performance. Methods: A 5-L anaerobic digester was used to conduct continuous batch tests to process swine manure and food waste. Four different stirring intervals of the digester were used: 5 min/h, 10 min/2 h, 15 min/3 h, and 20 min/4 h. Results: The application of swine manure to the digester every 5 min/h resulted in the highest production of biogas as well as the highest removal rates of volatile solids (VS) and total chemical oxygen demand. Stirring the digester with a mixture of swine manure and food waste at intervals of 5min/h and 10min/2 h produced the highest biogas yields of 515.3 mL/gVS and 521.1 mL/gVS, respectively. To test different supply frequencies, organic waste was added to the digester in either a 12-hor 24-h cycle. The 24-h cycle produced 1.5-fold greater biogas production than that during the 12-h cycle. Conclusions: Thus, from the above results, to optimize anaerobic digestion performance, the ideal stirring condition must be 5min/h for swine manure feeding and 10min/2h for co-digestion of food waste and swine manure in a 24-h cycle.

• Biotechnology and Bioprocess Engineering:BBE
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• 제9권3호
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• pp.184-190
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• 2004

The influences of impeller types on morphology and protein expression were investigated in a submerged culture of Aspergillus oryzae. The impeller types strongly affected mycelial morphology and protein production in batch and fed-batch fermentations. Cells that were cultured by propeller agitation grew in the form of a pellet, whereas cells that were cultured by turbine agitation grew in a freely dispersed-hyphal manner and in a clumped form. Pellet-grown cells showed high levels of protein production for both the intracellularly heterologous protein (${\beta}$-glucuronidase) and the extracellularly homologous protein (${\alpha}$-amylase). The feeding mode of the carbon source also influenced the morphological distribution and protein expression in fed-batch fermentation of A. oryzae. Pulsed-feeding mainly showed high protein expression and homogeneous distribution of pellet whereas continuous feeding resulted in less protein expression and heterogeneous distribution with pellet and dispersed-hyphae. The pellet growth with propeller agitation paralleling with the pulsed-feeding of carbon source showed a high level of protein production in the submerged fed-batch fermentation of recombinant A. oryzae.

• Environmental Engineering Research
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• 제23권1호
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• pp.114-119
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• 2018

Yarn dyed wastewater has to be treated prior to disposal into the water bodies due to its high content of harmful organic compounds. In this study, the performance of Chemical Oxygen Demand (COD) removal and kinetic rate constant are investigated via hybrid electrocoagulation-Fenton in a continuous system using wastewater discharged from a yarn dyed industry in Surabaya city. The wastewater was treated in a batch mode using electrocoagulation to reduce Total Suspended Solid, followed by Fenton method in a continuous system to reduce COD level. Various Fe(II) feeding modes, molar ratio of $Fe(II)/H_2O_2$, initial pH of wastewater, and flow rate are used in this study. The results show that COD removal process obeys a pseudo-first order kinetics. At $Fe(II)/H_2O_2$ ratio of 1:10, initial wastewater pH of 3.0, and feed flow rate of 30 mL/min, the COD removal efficiency was observed to be 80%, and the kinetic rate constant is $0.07046min^{-1}$. The chemical cost for the treatment estimated to be IDR 160 per L wastewater, which is cheaper than the previously reported batch system of IDR 256/L.

• 생명과학회지
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• 제14권1호
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• pp.167-173
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• 2004

Lactobacillus brevis BH-21의 균체를 고정화하여 column형 reactor를 이용하여 $\gamma$-aminobutyric acid의 연속적 생산을 검토하였다. Lactobacillus brevis BH-21에 의한 $\gamma$-aminobutyric acid 생산조건은 고정화 담체로는 3.0% sodium alginate가 좋았고 직경 2.2 mm의 bead를 사용하여 기질의 주입속도는 10 mL/h이 최적 조건이었다. Lactobacillus brevis BH-21의 고정화 균체와 유리 균체를 사용하여 $\gamma$-aminobutyric acid의 생산을 최적 조건하에서 1, 2, 3, 및 4차 발효 동안 48시간마다 신선한 기질을 주입하면서 비교ㆍ조사한 결과 고정화 균체를 사용 시에 생산량이 더 많았다. Column형 reactor에 의한 연속 발효 시 발효 25일까지 생산이 우수하였고 발효 30일까지는 $\gamma$-aminobutyric acid를 생산할 수 있었다.

• Parasites, Hosts and Diseases
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• 제56권1호
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• pp.53-59
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• 2018

Tick saliva is critically important for continuous attachment to the host, blood feeding for days, and transmission of tick-borne pathogens. To characterize the patterns of inflammatory cytokine gene expression during its attachment and blood sucking time, peripheral blood samples of rabbits infested with Haemaphysalis longicornis ticks were collected at different intervals. Blood histamine concentration was evaluated as well as gene encoding IFN-${\gamma}$, TNF-${\alpha}$, IL-2, IL-6, IL-4, and IL-10 were compared with non-infested rabbits. Blood histamine concentration of tick-infested rabbits during fast feeding time was significantly higher than that of non-infested rabbits. In both nymph and adult tick infested rabbits, expression of TNF-${\alpha}$ and IFN-${\gamma}$ genes were decreased significantly (P<0.05), while expression of IL-4, IL-6, and IL-10 were increased 1.3 to 7 folds in adult infested rabbits with the exception of IL-6 that was significantly (P<0.05) decreased in nymph infested rabbits. IL-2 was not expressed in either nymph or adult infestation. H. longicornis saliva is capable of modulate host responses through a complex correlation with histamine and Th1, Th2 mediated cytokines that suppress the inflammatory responses directed toward inflammatory mediators introduced into the host during tick feeding.

• 한국세라믹학회지
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• 제26권4호
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• pp.575-582
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• 1989

The effects of raw material feeding procedures and gelation temperatures on zeolite synthesis are investigated. Thus, the synthesis of zeolite 4A from sodium aluminate and sodium silicate solutions is chosen as a model reaction, for which equi-molar hydrogelation is performed with variation of feeding procedures and gelation temperatures. The formation of crystal nuclei, often being referred to as precursors, is induced under different conditions, the variation being examined by means of viscosity and water contents. The final products of zeolite 4A are evaluated by XRD, SEM morphology, particle size analysis and cation exchange capacity. Evidence shows that the viscosity of the initial products and their water contents are markedly influenced by the feeding methods of the reactant materials and by the gelation temperature. Further, it is found that the gelation at an elevated temperatures near 7$0^{\circ}C$ can be made possible through modification of mixing procedures. This provides convenient means of controlling the particle size of the final products. In this regard, a continuous flow-type mixing technique is proposed, which is demonstrated to be superior to the conventional batch-type mixings. The significance of this finding may lie in savings of equipment as well as energy costs, especialy on a large scale commercialization of zeolite production.