• 상하수도학회지
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• 제34권6호
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• pp.437-443
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• 2020

Biological phosphorus removal is accomplished by exposing PAO(phosphorus accumulating organisms) to anaerobic-aerobic conversion conditions. In the anaerobic condition, PAO synthesize PHB(polyhydroxybutyrate) and simultaneously hydrolysis of poly-p resulting phosphorus(Pi) release. In aerobic condition, PAO uptake phosphorus(Pi) more than they have released. In this study, cyanobacteria Synechococcus sp., which is known to be able to synthesize PHB like PAO, was exposed to anaerobic-aerobic conversion. If Synechococcus sp. can remove excess phosphorus by the same mechanism as PAO, synergistic effects can occur through photosynthesis. Moreover, Synechococcus sp. is known to be capable of synthesizing PHB using inorganic carbon as well as organic carbon, so even if the available capacity of organic carbon decreases, it was expected to show stable phosphorus removal efficiency. In 6 hours of anaerobic condition, phosphorus release occurred in both inorganic and organic carbon conditions but SPRR(specific phosphorus release rate) of both conditions was 10 mg-P/g-MLSS/day, which was significantly lower than that of PAO. When converting to aerobic conditions, SPUR(specific phosphorus uptake rate) was about 9 mg-P/g-MLSS/day in both conditions, showing a higher uptake rate than the control condition showing SPUR of 6.4 mg-P/g-MLSS/day. But there was no difference in terms of the total amount of removal. According to this study, at least, it seems to be inappropriate to apply Synechococcus sp. to luxury uptake process for phosphorus removal.

• Archives of Pharmacal Research
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• 제12권2호
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• pp.88-93
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• 1989

In order to obtain some informations about the effect of molecular weight on the release rate of drug from drug carrier, two types of poly-L-glutamic acid (PLGA)-cytarabine (ara-C) conjugates, PLGA-ara-C:I and PLGA-ara-C:II, were synthesized using two types of PLGA having different average molecular weight, 43,000 and 77,800, respectively. The PLGA-ara-C conjugates were synthesized by mixed anhydride method and found to be covalently linked. Both types of conjugates charged negatively at biological pH. The pH-dependent release rate of ara-C was observed in both cases, and the release rate was accelerated in basic, acidic conditions (the k values were 0.015 $day^{-1}$ at pH 7.0, 0.024 $day^{-1}$ at pH 5.0, and 0.059 $day^{-1}$ at pH 9.0 in the case of PLGA-ara-C:I) and in the presence of pretense. The time required for the release of 16.5% of ara-C from PLGA-ara-C:I were 8 hr and 144 hr in the presence and absence of protease, respectively. Although both types of conjugates showed similar drug substitution ratio, they showed different release rates. Between the two types of conjugates, PLGA-ara-C:II showed the faster release rate (0.030 vs 0.042 $day^{-1}$ in pH 7.4 phosphate buffer solution at $37^{\circ}C$) and the smaller activation energy for the release of drug (12.5 vs 7.7 Kcal/mol) than PLGA-ara-C:I. The characteristic effect of molecular weight on the release rates of PLGA-ara-C conjugates suggests that the drug release rate might be effectively controlled over a prolonged period of time by the combined use of the different types of PLGA-ara-C conjugates having different molecular weights.

• Ocean and Polar Research
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• 제42권3호
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• pp.225-231
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• 2020

The aim of this study was to examine optimal induction method for carpospore release from Agarophyton vermiculophyllum cystocarps for seedling production. We tested the effects of environmental factors on carpospore release by using five different induction methods; spontaneous, desiccation, low temperature, desiccation+low temperature, and osmotic shock. Also, carpospores release was estimated at three temperatures (20, 25, and 30℃), and then under combinations of three day lengths (8, 12, and 16h) and two irradiances (30 and 60 μmol photons m^-2 s^-1), after pretreatment at desiccation+low temperature for 2 hr. The number of carpospores released was between 113 ~ 682 spores /cystocarp/day and it was maximal in the desiccation+low temperature treatment. Optimal environmental conditions for carpospore release of A. vermiculophyllum were 25℃, 16 h, and 60 μmol photons m^-2 s^-1. The present results suggest that massive carpospores for seedling production of A. vermiculophyllum could be obtained under a combination of 25℃, 16 h, and 60 μmol photons m^-2 s^-1 after pretreatment in the desiccation+low temperature.

• 한국식물병리학회지
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• 제11권4호
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• pp.344-347
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• 1995

Factors affecting on the ascospore release of Mycosphaerella nawae, the causal organism of persimmon leaf casting disease, were investigated. The ascospore release of the pathogen occurred following the precipitation of rain. The ascospore release started from the beginning of raining, reached maximum at 2 hours after the precipitation of rain, and then decreased abruptly. When the inoculum source (a file of infected leaves) was submerged in water to imitate raining conditions, 92.5% of the total ascospores were released within 1 hour after submerging, 5.8% were after 2 hours, 1.4% were after 4 hours, 0.1% were after 8 hours, and none detected after 10 hours. The inoculum source overwintered in the field released ascospores much more and earlier than the inoculum source kept in the greenhouse. The first ascospore release was about 10 days earlier, and the amount of the total liberated spores was 3∼4 times higher in the field inoculum source than the greenhouse nioculum source. The early defoliated leaves (in early October) in the previous year produced ascospores twice more than the late defoliated leaves (in early November) produced.

• The Korean Journal of Physiology
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• 제14권1호
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• pp.25-30
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• 1980

It has been well known that beta-adrenoceptor is responsible for the renin release stimulatory and alpha-adrenoceptor may be inhibitory. It has been observed accidently that alpha-adrenergic agonist can inhibit renin release by just changing the medium temperature in Vitro experiment in this laboratory. A series of experiments were performed to clarify this interesting phenomena in Vitro experiment. Rat renal slices were incubated in PSS medium under gas phase at $37^{\circ}C$. The following results were observed. 1) Isoproterenol and norepinephrine resulted in renin release stimulatory in dose-dependent by the concentrations of $10^{-9}$ to $10^{-5}\;M/L$ at $37^{\circ}C$. 2) Norepinephrine resulted in renin release inhibitory in dose dependent by the concentrations of $10^{-7}$ to $10^{-5}\;M/L$, and almost no effect by isoproterenol $10^{-6}\;M/L$ at $20^{\circ}C$. 3) Phenoxybenzamine pretreatment at $37^{\circ}C$ accentuated isoproterenol stimulatory effect at $37^{\circ}C$. 4) Phenoxybenzamine pretreatment at $20^{\circ}C$ attenuated isoproterenol stimulatory effect at $37^{\circ}C$. These data suggest that the renal adrenoceptor(s) related to renin release maybe a single entity, and can be interconverted different forms in certain conditions.

• Archives of Pharmacal Research
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• 제12권3호
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• pp.186-190
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• 1989

The release rates of methotrexate (MTX) from MTX-human serum albumin (HSA) conjugate, and 5-fluorouracil (5-FU) from 5-FU acetic acid (AA)-HSA conjugate were determined after incubation of the conjugates in various conditions. The concentrations of 5-FU released from the conjugate increased monoexponentially, however those of MTX increased biexponentially in all studies. It indicated that there are two distinct types of MTX-HSA linkage, weakly and tightly bound linkages. The release rates of 5-FU were lower than those of MTX in all studies indicating that the bond of 5-FU-AA-HSA conjugate is very stable, which is supported by the higher value of activation energy (39. 9 vs 10. 7 Kcal/mole) using Arrhenius equation. The release rates of MTX and 5 -FU from the conjugates increased with incubation temperatures. Proteolytic enzyme and liver homogenates accelerated significantly the release rates of MTX and 5-FU. Approximately 1.30 and 22.0% of MTX were released after 12 hours of incubation in the absence and presence of protease, respectively. The corresponding values for 5-FU were released after 12 hours of incubation with rat liver homogenates which were diluted 6 times with phosphate buffer of pH 6.0. The MTX-HSA and 5-FU-AA-HSA conjugates were very stable in rat plasma.

• Archives of Pharmacal Research
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• 제17권4호
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• pp.226-230
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• 1994

The characteristics of voltage-dependent ^{45}Calcium$ uptake and norepinephrine release as factors controlling neural activities in the hypothalamus which is an important regulatory site for cardiovascular function wre studied. Two groups of animals : male spontaneously hyperterisive rat (SHR) and age-matched nomotensive wistar rat (NW) were used in this study. Animals at 4, 6 and 16 weeks of age were sacrificed by decapitiation and the hypothalamus was dissected out. Voltage-dependent calcium uptake and norepinephrine release were determined from hypothalamic synaptosomes either in low potassium (5 mM) or high potassium (41 mM) stimulatory conditions by using ^{45}Ca$ isotope and HPLC-ECD techniques. Degrees of voltage-dependent ^{45}Calcium$ uptake and norepinephrine release evoked by calcium uptake in the hypothalamus of prehypertensive phase (4 weeks old) of SHR were significantly smaller than those in NW of the same age. However, in the developmental phase (6 weeks old) and the established phase (16 weeks old) of hyperrtension in SHR, degrees of voltage-dependent ^{45}Calcium$ uptake and norepinephrine release were similar to those of age-matched normotensive wistae eats. These data imply that the deficit in hypothalamic norepinephrine release might be an important underlying factor for the development of hypertension in SHR.

• 상하수도학회지
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• 제13권2호
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• pp.89-94
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• 1999

In this study small glass columns with 2.5cm inner diameter and 24.5cm length were used as many as the sample numbers to study the effects of initial pH, temperature, dissolved oxygen concentration, and sediment depth on the release of phosphorus from lake sediment. No phosphorus release occurred at $10^{\circ}C$ with all pHs, and release rate at $25^{\circ}C$ was higher than that at $35^{\circ}C$ with pH 4 and reverse trends were observed at pH 7 and 10. Under all conditions, DO concentrations were decreased and equilibrium was obtained after 4-8 days when phosphorus release started and the Do concentrations were less than 1 mg/l. Sediment depth had little effect on phosphorus release rate. It was found that relation between released SRP(Soluble Reactive Phosphorus) concentration and time was zero order reaction and reaction rate coefficients were obtained. The amount of phosphorus release from lake sediment can be predicted by considering these k values.

• 한국분무공학회지
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• 제8권4호
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• pp.9-16
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• 2003

The Purpose of this study is to investigate the relationships between the local heat release rate and CH concentration have been investigated by numerical simulations of methane-air premixed flames. And simultaneous CH and OH PLIF(Planar Laser Induced Fluorescence) measurement has been also conducted for lean premixed flame as well as for laminar flames. Numerical simulations are conducted for laminar premixed flames and turbulent ones by using PREMIX in CHEMKIN and two dimensional DNS code with GRI mechanism version 2.11, respectively. In the case of laminar premixed flame, the distance between the peak of heat release rate and that of CH concentration is under $91{\mu}m$ for all equivalence ratio calculated in present work. Even for the premixed flame in high intensity turbulence, the distribution of the heat release rate coincides with that of CH mole fraction. For CH PLIF measurements in the laminar premixed flame burner, CH fluorescence intensity as a function of equivalence ratio shows a similar trend with CH mole fraction computed by GRI mechanism. Simultaneous CH and OH PLIF measurement gave us useful information of instantaneous reaction zone. In addition, CH fluorescence can be measured even for lean conditions where CH mole fraction significantly decreases compared with that of stoichiometric condition. It was found that CH PLIF measurements can be applicable to the estimation of the spatial fluctuations of heat release rate in the engine combustion.

• 약학회지
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• 제32권1호
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• pp.26-39
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• 1988

Eudragit $RS^{\circledR}$ polymer was used as a wall material for the microencapsulation of aspirin by a phase separation method from chloroform-cyclohexane system with 5% polyisobutylene (PIB) in cyclohexane, and microcapsules obtained were evaluated by particle size analysis, scanning electron microscopy (SEM), drug release and drug stability test. With PIB as a coacervation inducing agent, smooth and tight microcapsules with less aggregation were obtained. Below 1 : 0.3 core-wall ratio, it was possible to coat individual particle. Variation of production conditions showed that increasing the proportion of wall material, particle size and wall thickness of microcapsules and the concentration of paraffin wax in cyclohexane as a sealant sustained drug release rates effectively. SEM confirmed that larger microcapsules after drug release did not rupture into smaller particles but contained a few small pores on the surface. Aspirin release from Eudragit $RS^{\circledR}$ coated microcapsules was independent of the pH of medium, and the mechanism of drug release from non-sealed and sealed microcapsules appeared to fit Higuchi matrix model kinetics. Aspirin in the mixture of aspirin microcapsules and sodium bicarbonate was by far more stable than that in the mixture of pure aspirin and sodium bicarbonate.