• Restorative Dentistry and Endodontics
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• v.24 no.2
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• pp.330-336
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• 1999

In biological systems, the mineral that forms hard tissue is of an apatitic nature, and hydroxyapatite($Ca_5OH(PO_4)_3$: HA) is generally considered as the prototype for such a mineral. Thus, the precipitation of HA, having biological implications, has been the subject of several investigations. Crystal growth studies using HA seeds in supersaturated solutions have enhanced our understanding of the process and mechanism involved in seeded crystal growth. From these studies, it has become apparent that the precipitation rate of HA onto the seed crystals depends on the various conditions, especially on the additives. The relation between the supersaturated solution containing fluoride and the process of HA crystal growth enhances the understanding of mechanism of HA crystal growth. Until recently, the studies have been on the crystal growth of enamel minerals and synthetic HA seeds in the supersaturated solution containing 1~2 ppm fluoride. The purpose of the present investigation is to study the effect that fluoride of high concentration has on the crystal growth kinetics of HA. In order to produce the composition found in the secretory enamel fluid, experimental solutions of 1mM Ca, 3mM P, and 100mM Tris as background electrolyte were used. Then this experimental solutions were added to 0, 2, 4, 6, 8, 10 ppm fluoride. The effect of fluoride at high concentrations on the precipitation was examined in a bench-top crystal growth model adopting a miniaturized reaction column. Chemical analysis was employed for characterization of working solutions before and after the experimentation. Remarkable findings were : 1) the amount of crystal growth was gradually accelerated as the fluoride concentration increased until 6 ppm, but decreased in 8 and 10 ppm fluoride; 2) the amount of fluoride ion consumed in crystal formation was constant despite the increase in fluoride concentration.

• Journal of Korean Society on Water Environment
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• v.34 no.4
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• pp.375-381
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• 2018

The monitoring of phytoplankton biomass and community structure is essential as a first step to control the harmful cyanobacterial blooms in freshwater systems, such as seen in rivers and lakes, due to the process of eutrophication and climate change. In order to quantify the biomass of phytoplankton with a wide range in size and shape, the measurement of cell biovolume along with cell density is required for a comprehensive review on this issue. However, most routine monitoring programs preserve the gathered phytoplankton samples before analysis using chemical additives, because of the constraint of time and the number of samples. The purpose of this study was to investigate the cell biovolume change characteristics of six cyanobacterial species, which are common bloom-causing cyanobacteria in the Nakdong River, after the preservation with Lugol's iodine solution. All species showed a statistically significant difference after the addition of Lugol's iodine solution compared to the live cell biovolume, and the cell biovolume decreased to the level of 34.0 ~ 56.3 % at maximum in each species after the preservation. The nonlinear regression models for determining the shrinkage ratio by a preservation period were derived by using the cell biovolume measured until 180 days preservation of each target species, and the equation to convert the cell biovolume measured after preservation for a certain period to the cell biovolume of viable cell was derived using that formula. The conversion equation derived from this study can be used to estimate the actual cell biovolume in the natural environment at the time of sampling, by using the measured biovolume after the preservation in the phytoplankton monitoring. Moreover this is expected to contribute to the final interpretation of the water quality and aquatic ecosystem impacts due to the cyanobacterial blooms.

• Journal of the Korean Applied Science and Technology
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• v.37 no.6
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• pp.1678-1686
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• 2020

This study attempted to derive the possibility of using wood pellet using rice husk, which is an agricultural byproduct, and tried to improve the lower calorific value of rice hulls thorough expansion technology and combustion additives. In the physical and chemical analysis of rice husk, the result was obtained that the chlorine content was 0.09%, which did not meet the wood pellet quality standard of Korea. When making rice hulls into expanded rice husk through the expansion technology, the chlorine content decreased, resulting in a product of 0.02%, which is equivalent to the wood pellet standard of Korea, and the calorific value was also increased to 4,280 kcal/kg compared to the existing 3,780 kcal/kg. To obtain a product of 5,000 kcal/kg or more, borax, hydrogen peroxide, and sodium hydroxide was used as combustion improver. However the improvement in calorific value was insufficient. After conversion to coffee oil path using coffee grounds, which is a waste resource biomass, it is mixed into an expanded rice husk, and when the product is analyzed, the coffee oil 15 wt% mixed product shows an excess of 4,949 kcal/kg. When using rice husk, an agricultural byproduct, as wood pellets, it is considered desirable to use waste resources to improve the calorific value, and according to the results of this study, when mixing coffee oil, rice husk can be sufficiently used as wooden pellets.

• Journal of Animal Science and Technology
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• v.64 no.1
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• pp.38-51
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• 2022

Whole-plant corn (Zea may L.) and sorghum-sudangrass hybrid [Sorghum bicolor (L.) Moench] are major summer crops that can be fed as direct-cut or silage. Proso millet is a short-season growing crop with distinct agronomic characteristics that can be productive in marginal lands. However, information is limited about the potential production, feed value, and ensilability of proso millet forage. We evaluated proso millet as a silage crop in comparison with conventional silage crops. Proso millet was sown on June 8 and harvested on September 5 at soft-dough stage. Corn and sorghum-sudangrass hybrid were planted on May 10 and harvested on September 10 at the half milk-line and soft-dough stages, respectively. The fermentation was evaluated at 1, 2, 3, 5, 10, 15, 20, 30, and 45 days after ensiling. Although forage yield of proso millet was lower than corn and sorghum-sudangrass hybrid, its relative feed value was greater than sorghum-sudangrass hybrid. Concentrations of dry matter (DM), crude protein, and water-soluble carbohydrate decreased commonly in the ensiling forage crops. The DM loss was greater in proso millet than those in corn and sorghum-sudangrass hybrid. The in vitro dry matter digestibility declined in the forage crops as fermentation progressed. In the early stages of fermentation, pH dropped rapidly, which was stabilized in the later stages. Compared to corn and sorghum-sudangrass hybrid, the concentration of ammonia-nitrogen was greater in proso millet. The count of lactic acid bacteria reached the maximum level on day 10, with the values of 6.96, 7.77, and 6.95 Log₁₀ CFU/g fresh weight for proso millet, corn, and sorghum-sudangrass hybrid, respectively. As ensiling progressed, the concentrations of lactic acid and acetic acid of the three crops increased and lactic acid proportion became higher in the order of sorghum-sudangrass hybrid, corn, and proso millet. Overall, the shorter, fast-growing proso millet comparing with corn and sorghum-sudangrass hybrid makes this forage crop an alternative option, particularly in areas where agricultural inputs are limited. However, additional research is needed to evaluate the efficacy of viable strategies such as chemical additives or microbial inoculants to minimize ammonia-nitrogen formation and DM loss during ensiling.

• Animal Bioscience
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• v.35 no.12
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• pp.1871-1880
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• 2022

Objective: The primary goal was to identify the effectiveness of chemical or biological additives in delaying the deterioration of early-harvested wilted rye silage after exposure to air. Methods: Rye harvested as a whole plant at the early heading stage was wilted for 24 h. The wilted forage was divided into treatments including sodium diacetate (SDA) at 3 (SDA3) and 6 g/kg (SDA6), Lactobacillus plantarum (LP), L. buchneri (LB), or their equal mixture (LP+LB) at 1×10⁶ colony-forming unit/g fresh matter. Results: After 60 d of conservation in 20-L silos, lactic acid was greater in LP and LP+LB silages than other treatments (102 vs 90.2 g/kg dry matter [DM]). Acetic acid was greatest in SDA6 (32.0 g/kg DM) followed by LB (26.1 g/kg DM) and was lowest in LP treatment (4.73 g/kg DM). Silage pH was lower with microbial inoculation and the lowest and highest values were observed in LP and untreated silages, respectively. After 60 d, neutral detergent fiber concentration was lowest in SDA6 silages, resulting in the greatest in vitro DM digestibility (846 g/kg DM). Aerobic stability was longest in SDA6 (176 h) followed by LB treatment (134 h). Instability after aerobiosis was greatest in LP silages (68 h), about 8 h less than untreated silages. After aerobic exposure, yeast and mold numbers were lowest in SDA6 silages, resulting in DM loss minimization. Exhaustion of acetic acid and lactic acid after aerobic exposure was lowest with SDA6 but greatest with untreated and LP silages. Conclusion: Treatment of early-cut wilted rye forage with SDA at 6 g/kg resulted in silages with higher feeding value and fermentation quality, and substantially delayed deterioration after aerobic exposure, potentially qualifying SDA at this load for promotion of silage quality and delaying aerobic spoilage of early-harvested (low DM) rye forage.

• Journal of Microbiology and Biotechnology
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• v.33 no.4
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• pp.552-558
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• 2023

Levulinic acid (LA) is a valuable chemical used in fuel additives, fragrances, and polymers. In this study, we proposed possible biosynthetic pathways for LA production from lignin and poly(ethylene terephthalate). We also created a genetically encoded biosensor responsive to LA, which can be used for screening and evolving the LA biosynthesis pathway genes, by employing an LvaR transcriptional regulator of Pseudomonas putida KT2440 to express a fluorescent reporter gene. The LvaR regulator senses LA as a cognate ligand. The LA biosensor was first examined in an Escherichia coli strain and was found to be non-functional. When the host of the LA biosensor was switched from E. coli to P. putida KT2440, the LA biosensor showed a linear correlation between fluorescence intensity and LA concentration in the range of 0.156-10 mM LA. In addition, we determined that 0.156 mM LA was the limit of LA detection in P. putida KT2440 harboring an LA-responsive biosensor. The maximal fluorescence increase was 12.3-fold in the presence of 10 mM LA compared to that in the absence of LA. The individual cell responses to LA concentrations reflected the population-averaged responses, which enabled high-throughput screening of enzymes and metabolic pathways involved in LA biosynthesis and sustainable production of LA in engineered microbes.

• Journal of the Korean Applied Science and Technology
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• v.41 no.2
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• pp.375-385
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• 2024

The purpose of this study is to manufacture ice cream with perilla leaves fermented extract(5%, 10%, 15%, and 20% w/v) fermented by Lactobacillus acidophilus KCTC 3164 strain as functional additives. The physical and chemical properties(color, viscosity, pH, total acidity, melting rate, overrun) and antioxidant activity of ice cream with perilla leaves fermented extract were evaluated. The addition of perilla leaves fermented extract affected the color of the ice cream, and the melting rate increased with increasing addition of perilla leaves fermented extract. In contrast, viscosity showed a gradual decrease. Overrun increased gradually with higher levels of perilla leaves fermented extract, while pH decreased significantly, and total acidity increased. The DPPH radical scavenging activity and total polyphenol content of ice cream with perilla leaves fermented extract significantly increased with higher concentrations of fermented perilla leaves extract. The results of this study indicate that the ice cream sample with 10% fermented perilla leaves extract has a potential as a functional ice cream since it exhibited high overrun, a low melting rate, the desired viscosity, and high DPPH radical scavenging activity and total polyphenol content.

• Journal of Animal Science and Technology
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• v.45 no.2
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• pp.283-296
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• 2003

Emulsion-type sausages were manufactured to investigate the effects of CLA-vegetable oils and CLA-lard on quality characteristics of emulsion-type sausage. Each treatments replaced pork back fat with CLA-corn oil (CLA-CO), CLA-safflower seed oil (CLA-SSO) and CLA-lard (CLA-LD) were stored during 1, 7, 14, 21 and 28 days at 4$^{\circ}C$. The changes in physico-chemical properties, texture, thiobarbituric acid reactive substances (TBARS), fatty acid composition and CLA content of each treatments were measured during 1, 7, 14, 21 and 28 days at 4$^{\circ}C$. During storage, pH of control showed higher pH value than that of CLA-vegetable and CLA-lard treatments. The pH values of all treatments was significantly low at storage 14 days (p<0.05). The color L* and a*-value of all the treatments was not significantly changed with the storage periods. Color b*-value of CLA-treatments was higher than that of control during the storage period. Fatty acids composition was changed by addition of CLA-vegetable oils and CLA-lard. All kinds of fatty acids composition were decreased with CLA replacements than that of the control. Whereas linolenic acid content extremely increased by replacement of CLA-vegetable. CLA content of CLA-treatments was extremely increased than that of the control. The cohesiveness, springness, gumminess and brittleness of CLA-LD treatment was significantly higher (P<0.05) than that of the other treatments. The TBARS value of all treatments were significantly increased (P<0.05) as the storage period was passed. TBARS of sausage products containing CLA-CO was the lowest. Summing up the a forementioned results, emulsion-type sausage manufacturing with CLA-vegetable oil and CLA-lard was not affected in physico-chemical properties and texture characteristics. Also, it may be assumed that the high quality sausage can be manufactured with the extent of storage period and CLA accumulation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.3
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• pp.285-290
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• 2001

To utilize canned oyster processing waste water effectively, this study was carried out to prepare instant powdered soup using the waste water (IPSW), Instant powdered souu from oyster hot-water extracts (IPSE) was prepared by mixing hot-water extracts powder (15 g) with table salt (5 g), cream powder (19 g), milk replacer (12 g), wheat flour (20 g), corn flour (15 g), starch (5 g), glucose (7.5 g) and onion powder (1.5 g). In preparing IPSW, mixed powder from wash water and boiling liquid waste, instead of powder from hot-water extracts and table salt, was added (powder from boiling liquid waste: powder from wash water= 12: 8) and other additives were added in proportion to those in the IPSE, The IPSW consists mainly of carbohydrates (about $72\%$). It was not different from the IPSE. The volatile basic nitrogen, viable cell counts, coliform group of the IPSW contains 33.4 mg/100g, $2.2\times10^4CFU/g$, <180 MPN/100g, respectively, and its water activity has 0.257. So it was a hygienically safe and conservable instant food. The main fatty acids of IPSW were 16: 0 and 18: 1n-9. Its chemical score of protein was $61.4\%$ and its main inorganic matter was iron. According to a sensual evaluation, in contrast to the IPSE, the IPSW had a bit lower aroma but better taste, It was concluded from the above chemical and sensory evaluation that even the boiling liquid waste which had been mostly abandoned because of its high table salt content can be used as a good material for instant powdered soup if it's powdered and mixed adequately with powder from wash water, and its table salt content is properly adjusted.

• The Korean Journal of Mycology
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• v.29 no.2
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• pp.79-85
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• 2001

A strain of Dictyophora echinovolvata ASI 32002 showing good fruiting body formation was selected. Analyses of chemical and nutritional components as well as antimicrobial activity of different parts of the mushroom such as mycelium, egg, and fruiting body were carried out. There were differences in the chemical compositions and the quantities depending on developmental stages of veiled lady mushroom, D. echinovolvata ASI 32002. Nitrogen, phosphate, magnesium, and calcium in inorganic chemicals were abundant in mycelium, and potassium and mineral elements were abundant in the egg and fruiting body. Mannitol and trehalose were abundant in free sugar contents. Glutamic acid and arginine in mycelium and aspartic acid and glutamic acid in egg and fruiting body were abundant in free amino acid contents. Linoleic acid, an polyunsaturated fatty acid, was abundant in all parts of the Dictyophora species, but compositions and quantities of other fatty acids varied depending on the different parts of the mushroom. It was detected that malic acid, lactic acid and acetic acid in mycelium, formic acid, acetic acid and fumaric acid in egg, and malic acid, citric acid, lactic acid, fumaric acid in fruiting body were abundant. The methanol extracts of D. echinovolvata ASI 32002 mycelium showed antifungal activity with minimal inhibition concentration (MIC) of $62{\sim}125\;{\mu}g/ml$ that was similar levels of cyclohexamide against Aspergillus awamori, Hypocrea nigricance and Trichoderma virens. The MIC of extracts from mycelium and fruiting body against Candida albicans was $250\;{\mu}g/ml$, similar to that of tetracycline. In addition to the above results, further as food additives and ingredient of cosmetics.