• Bulletin of the Korean Chemical Society
• /
• v.7 no.1
• /
• pp.53-55
• /
• 1986

The $trans{\rightarrow}cis$ photoisomerization and fluorescence of trans-1,2-bispyrazylethylene were investigated in various conditions. The quantum yields of the $trans{\rightarrow}cis$ photoisomerization and the fluorescence intensity of trans-1,2-bispyrazylethylene decrease on going from neutral to acidic or basic solutions. The quantum yields of photoisomerization, however, are little affected by changing the concentration of salt while the fluorescence intensity increases as the concentration of salt increases. pH and salt effects on the energy levels of $^1(n,\;{\pi}^*)\;and\;^1({\pi},\; {\pi}^*)$ states lead to opposing changes in photoisomerization and fluorescence quantum yields. The heavy atom effect on the fluorescence of 1,2-bispyrazylethylene was also investigated.

• Economic and Environmental Geology
• /
• v.54 no.3
• /
• pp.331-352
• /
• 2021

The relationship of both heavy metals and major elements in soil, plants, and groundwater was studied in a hyper-arid area and depends completely on the groundwater to cover its all needs. The study reviles that 27.3% of the studied groundwater was strongly acidic and has very low pH values (

• Korean Chemical Engineering Research
• /
• v.62 no.4
• /
• pp.281-295
• /
• 2024

This review examines the effects of different process parameters on the production of lactic acid. Especially focusing on the factors such as, pH, temperature, utilization of fungi, viz., Rhizopus species and selection of carbon and nitrogen sources. The development of lactic acid synthesis is promoted by acidic environment, usually falling within pH < 3.5, which allows optimal lactic acid synthesis. Another important factor is temperature. Strains such as lactobacillus rhamnosus DUT1908, have a high tolerance to temperature as high as 50℃, which allows for effective substrate utilization and high lactic acid yield. This review highlights the need of tailoring these process parameters to the specific characteristics of the biomass and the metabolic pathways of the microorganisms to achieve increased lactic acid production.

• Food Science of Animal Resources
• /
• v.42 no.1
• /
• pp.73-83
• /
• 2022

The aim of this study is to determine the effects of using emulsion manufactured with soybeans (ES) to substitute chicken breast in Vienna sausages. Four types of Vienna sausages (S1: 10% ES and 50% chicken, S2: 20% ES and 40% chicken, S3: 30% ES and 30% chicken, and S4: 40% ES and 20% chicken) for this study were made. The pH, color, proximate composition, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), microphotographs, cooking yields, and texture profile analysis of sausages were examined. The pH value of uncooked and cooked sausages increased significantly with increasing ES content (p<0.05). The crude protein contents of S2, S3, and S4 were significantly higher than that of the control (p<0.05). Furthermore, the SDS-PAGE results showed that α-conglycinin, β-conglycinin, and the acidic subunit of glycinin all increased with increasing ES content. Microphotographs revealed that increasing the ES content decreased the size of fat globules. The cooking yields of samples increased significantly with increasing ES content (p<0.05). The hardness values of ES treated samples were significantly lower than that of the control (p<0.05). Therefore, 30% substitute of chicken breast with ES can improve the quality and structure of Vienna sausage, without inducing critical defects.

• Archives of Pharmacal Research
• /
• v.12 no.2
• /
• pp.88-93
• /
• 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.

• Journal of the Korean Applied Science and Technology
• /
• v.33 no.3
• /
• pp.599-605
• /
• 2016

Serratia marcescens, a Gram-negative bacterium characterized by production of a nondiffusible red pigment. Serratia marcescens 2354 (ATCC 25419) was production and purification a high concentration of red pigments when growing on Cang's soytone (CS) culture broth with soytone and ethanol. The optimal temperature and intial pH range for the production of the red pigments were $28^{\circ}C$ and pH 7.5, respectively. The red pigments was separated and purified through organic solvents extraction. Characterization of the red pigments is studied by UV-spectrophotometer at ${\lambda}_{max}$ 537 nm. The HPLC-Mass analysis of the partially purified compounds showed two major peaks with the molecular masses of 537 and 565 g. The red pigments were stable at room temperature under the acidic pH (up to pH 6) but were unstable at the strong alkaline condition. And red pigments were stable at sun light.

• Korean Journal of Food Science and Technology
• /
• v.30 no.2
• /
• pp.293-298
• /
• 1998

Allithiamine was synthesized when thiamine was mixed with fresh garlic extract made with ethanol at a alkali medium. Allithiamine was isolated and purified using solvents such as ethyl acetate, diethyl ether and benzene. Purified allithiamine was identified by determination of melting point, elemental analyzer and LC/Thermospray/Mass-spectrometer. On the other hand, synthetic conditions of allithiamine from fresh garlic, pH, temperature and ratio of garlic to ethanol were investigated. Synthetic rates of allithiamine under alkali conditions were rapidly increased while those under acidic conditions very slowly increased. The synthetic rates of allithiamine increased as temperature increased, but decreased above $70^{\circ}C$ as reaction time increased. There was no significant difference in synthetic rate of allithiamine when garlic was mixed above 4 times of ethanol. Therefore, optimum condition of pH, temperature and ratio of garlic to ethanol for synthesis of allithiamine were 8, $60^{\circ}C$ and 1 : 4, respectively.

• Microbiology and Biotechnology Letters
• /
• v.20 no.5
• /
• pp.534-542
• /
• 1992

Trypsin inhibtor produced by Streptomyces sp. S-217 was purified by solvent extraction and various column chromatographies. and physico-chemical properties of the inhibitor were investigated. Inhibitor complex was formed for incubation of 10 min. Streptomyces 5-217 showed the highest production of trypsin inhibitor when it was cultivated at $37^{\circ}C$ for 66 hr in the medium containing 2% mannitol & 0.9% peptone, pH 7.0. Trypsin inhibitor was purified by column chromatography and high performance liquid chromatography. Trypsin inhibitor indicated the maxium wavelength at 215 nm and solubilities in water, methanol and dimethyl sulfoxide were 95, 70 and 75%, respectively. The concentration of 50% inhibition ($IC^{50}$) was 15 $\mu$g/ml. The inhibitor was stable on heating at $100^{\circ}C$ for 60 min in pH 5~9 and was more stable in alkaline region than acidic region.

• Food Science and Preservation
• /
• v.12 no.5
• /
• pp.489-495
• /
• 2005

Polyphenol oxidase (PPO) from Burdock (Arctium lappa L.) was purified and characterized. Purification of polyphenol oxidase was achieved by ammonium sulfate precipitation, Phenyl-sepharose CL-4B hydrophobic chromatography and Sephadex G-100 gel filtration chromatography. The molecular mass of the purified PPO was estimated to be 30 kDa by SDS polyacrylamide gel electrophoresis. In a substrate specificity, maximum activity was achieved with chlorogenic acid, followed by catechol and catechin. Whereas, there was low activity with hydroquinic acid, resorcinol or tyrosine. The optimum pH and temperature for enzyme activity were 7.0 and 35$\circC$ with catechol, respectively. The enzyme was most stable at pH 7.0 while unstable at acidic and alkaline pH. The enzyme was stable when heated to 40$\circC$. But heating at 50$\circC$ for more than 30 min caused 50% loss of activity. Ascorbic acid, L-cystein and $Cu^{2+}$ inhibited the activity of pholyphenol oxidase.

• Korean Journal of Food Science and Technology
• /
• v.25 no.4
• /
• pp.360-365
• /
• 1993

This study was carried out to examine the effects of phytate addition on the solubility and digestibility of the low-phytate soy protein isolate (LSPI) and high-phytate soy protein isolate (HSPI). In SDS-polyacrylamide gel electrophoresis of soy protein isolate, different patterns of proteins were observed in both HSPI and LSPI at various phytate and pH levels, suggesting that phytate may bind specifically to certain protein fractions at a particular pH. For example, proteins of M.W $1.8{\sim}3.5\;kDa$ resisted phytate binding at acidic pH. LSPI was fractionated into albumin, globulin, gliadin and glutelin, and phytate was shown to bind with difficultly to all three gliadin bands. Effects of phytate on the pepsin digestibility of soy proteins were apparent, especially in the short term digestion.