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Variation of Selected Phenotypic Characteristics, Anthocyanins and Bitter Sesquiterpene Lactones in Lettuce (Lactuca sativa L.) Germplasm (상추(Lactuca sativa L.)유전자원의 형태 특성 및 Anthocyanins과 Bitter Sesquiterpene Lactones 변이)

  • Choi, Susanna;Assefa, Awraris Derbie;Lee, Jae-Eun;Hur, On-Sook;Ro, Na-Young;Lee, Ho-Sun;Noh, Jae-Jong;Hwang, Ae-Jin;Kim, Yeong-Jee;Kim, Bich-Saem;Ko, Ho-Cheol;Rhee, Ju-Hee
    • Proceedings of the Plant Resources Society of Korea Conference
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    • 2019.10a
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    • pp.95-95
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    • 2019
  • 상추(Lactuca sativa L.)는 대표적인 쌈 및 샐러드 채소로 우리나라 기준(2016년) 3,387 ha의 면적에서 86,128톤을 생산하여 엽채류 중 배추, 양배추 다음으로 많이 생산되는 작물이다. 안토시아닌(Anthocyanins)은 열매, 꽃, 줄기, 잎 등 식물계에 널리 분포되어 있는 페놀 화합물 중 하나로 적색, 자색 등의 색을 나타내는 수용성 flavonoid계 색소이다. BSLs (Bitter sesquiterpene lactones)는 항암, 항균, 해열과 염증완화에 효과가 있는 것으로 알려져 있다. 본 연구는 농촌진흥청 농업유전자원센터에서 보유 중인 상추 66자원의 형태학적 특성 및 액체크로마토그래피(HPLC, UPLC)를 이용한 안토시아닌과 BSLs성분을 분석하여 함량이 높은 자원을 선발하고자 한다. 상추시료 0.05 g을 $MeOH/H_2O/AcAc$로 추출 한 후, UPLC를 사용하여 안토시아닌 함량을 분석하였으며, 상추시료 0.25 g을 100% MeOH로 추출 한 후 HPLC를 사용하여 BSLs 함량을 분석하였다. 연구 결과, 상추 유전자원의 안토시아닌 함량 범위는 0 mg/100 g에서 371.94 mg/100 g이고, BSLs성분 함량 범위는 $60.28{\mu}g/g\;DW$에서 $2821.92{\mu}g/g\;DW$ 이었다. 상추 66자원 중 안토시아닌함량이 200 mg/100 g이상인 자원은 IT217012, IT218395, IT231524, IT231525, IT260852이며, BSLs 함량이 $1700{\mu}g/g\;DW$이상인 자원은 IT231524, IT231525, IT231527, IT264971, IT271118이다. 두 성분의 함량이 모두 높은 자원 IT231524와 IT231525 이었다. 이 두자원의 형태적 특성은 초형이 잎상추로 잎이 넓은 타원형에 가장자리 결각이 강한 자주색이다. 따라서 본 연구는 다양한 상추 유전자원의 형태학적 특성 및 BSLs, 안토시아닌 성분이 높은 자원을 선발하여 육종소재로 활용하고자 한다.

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A study on the awareness about "Dong-YI(東夷)" in Confucianism scripture (유교경전의 동이 인식에 관한 연구 - 13경 및 그 주석서를 중심으로 -)

  • Ham, HyunChan
    • The Journal of Korean Philosophical History
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    • no.30
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    • pp.123-159
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    • 2010
  • Dongyi (Chinese: 東夷; pinyin: $D{\bar{o}}ngy{\acute{i}}$; Wade-Giles: Tung-yi; literally "eastern 'barbarians'") was a collective term for people in eastern China and in the east of China. People referred to as Dongyi vary across the ages. The early Dongyi culture was one of earliest neolithic cultures in China. According to the earliest Chinese record, Zuo Zhuan, the Shang Dynasty was attacked by King Wu of Zhou, while attacking Dongyi, and collapsed afterwards Dongyi culture was one of the oldest neolithic cultures in China. Some Chinese scholars extend the historical use of Dongyi to prehistoric times, according to this belief, the neolithic culture correlates to Houli culture, Beixin culture, Dawenkou culture, Longshan culture and Yueshi culture, five evolutionary phases. Deliang He, thinks that Dongyi culture used to be one of the leading cultures in neolithic China. The writing system of Dongyi was one of the oldest writing systems in neolithic China. There are opinions that the 20 pictogram characters discovered in a Dongyi tomb (山東?縣大汶口墓葬) in Shangdong indictates some of the characters found, like "旦, 越, 斤, 皇, 封, 酒, 拍, ?", are still used in Chinese characters. There are also opinions that Dongyi people were the inventor of arrows. Some classic Chinese history records like Zuo Zhuan, Shuowen Jiezi, Classic of Rites, all have some similar records about this. [3][4] The legendary god of archery in Chinese mythology, Houyi, could also be a Dongyi leader. Based on archeology findings, Dongyi people's ancestral worship totem is bird-shaped. In the meantime, The fundamental thing that Koreans should do is to find out Korean identy. Koreans cannot achieve their goals unless they enforce politics economics, educations, etc. in harmony with their own identity. However, some people say that Koreans do not have any dentity on the grounds that there is no Korean traditional thought. This view is, however, absolutely absurd because it is impossible for a nation to exist for oner five thousand years without having it's own native characteristics. The most essential thought in Korean identity is Confucius' In(仁). In is originated from Yi(夷) or Yi-jok(夷族)'s heart. On this account, Confucius' In can be a precious thought to Korean people who have been suffering from many problem caused by the absence of Korean identity. If Korean could understand their original characteristics and if Korean couldrealize that their original characteristics are Confucius' In, then our culture and identity recovery of though may maximize efficiency of country and society development.

Anti-hyperlipidemic and anti-obesity effects of Sparassis latifolia fruiting bodies in high-fat and cholesterol-diet-induced hyperlipidemic rats (고지방과 고콜레스테롤 식이 급여에 의해 고지혈증이 유도된 흰쥐에서 꽃송이버섯 자실체의 항고지혈증과 항비만 효과)

  • Im, Kyung-Hoan;Baek, Seung-A;Choi, Jaehyuk;Lee, Tae-Soo
    • Journal of Mushroom
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    • v.19 no.1
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    • pp.23-32
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    • 2021
  • This study investigated the anti-hyperlipidemic and anti-obesity effects of Sparassis latifolia (S. latifolia) fruiting body powder in rats fed with a high fat and cholesterol diet (HFD). Rats were fed a normal control diet (ND), an HFD, an HFD supplemented with 5% fruiting body powder of S. latifolia (HFD+SL), or an HFD supplemented with 0.03% simvastatin (HFD+SS), for 6 weeks. The HFD group demonstrated considerable increase in body weight gain, the food efficiency ratio (FER), and plasma cholesterol and triglyceride levels, compared to the ND group. In contrast, the HFD+SL and HFD+SS groups showed significantly reduced body weight gain, food intake, and plasma cholesterol and triglyceride levels compared to the HFD group. In particular, the HFD+SL and HFD+SS diets significantly suppressed the occurrence of non-alcoholic fat deposits in the liver. Taken together, these results suggest that dietary supplementation of the fruiting body powder of S. latifolia in an HFD could lower the risks of hyperlipidemia, atherogenesis, and obesity and may be used as a functional food to manage cardiovascular disease and fecal lipid and cholesterol levels.

Dehydration of Lactic Acid to Bio-acrylic Acid over NaY Zeolites: Effect of Calcium Promotion and KOH Treatment (NaY 제올라이트 촉매 상에서 젖산 탈수반응을 통한 바이오아크릴산 생산: Ca 함침 및 KOH 처리 영향)

  • Jichan, Kim;Sumin, Seo;Jungho, Jae
    • Clean Technology
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    • v.28 no.4
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    • pp.269-277
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    • 2022
  • With the recent development of the biological enzymatic reaction industry, lactic acid (LA) can be mass-produced from biomass sources. In particular, a catalytic process that converts LA into acrylic acid (AA) is receiving much attention because AA is used widely in the petrochemical industry as a monomer for superabsorbent polymers (SAP) and as an adhesive for displays. In the LA conversion process, NaY zeolites have been previously shown to be a high-activity catalyst, which improves AA selectivity and long-term stability. However, NaY zeolites suffer from fast deactivation due to severe coking. Therefore, the aim of this study is to modify the acid-base properties of the NaY zeolite to address this shortcoming. First, base promoters, Ca ions, were introduced to the NaY zeolites to tune their acidity and basicity via ion exchange (IE) and incipient wetness impregnation (IWI). The IWI method showed superior catalyst selectivity and stability compared to the IE method, maintaining a high AA yield of approximately 40% during the 16 h reaction. Based on the NH3- and CO2-TPD results, the calcium salts that impregnated into the NaY zeolites were proposed to exit as an oxide form mainly at the exterior surface of NaY and act as additional base sites to promote the dehydration of LA to AA. The NaY zeolites were further treated with KOH before calcium impregnation to reduce the total acidity and improve the dispersion of calcium through the mesopores formed by KOH-induced desilication. However, this KOH treatment did not lead to enhanced AA selectivity. Finally, calcium loading was increased from 1wt% to 5wt% to maximize the amount of base sites. The increased basicity improved the AA selectivity substantially to 65% at 100% conversion while maintaining high activity during a 24 h reaction. Our results suggest that controlling the basicity of the catalyst is key to obtaining high AA selectivity and high catalyst stability.

A Wide Region of Tropical Asia Adaptable Japonica Rice 'Asemi' (아시아 광지역 적응성 자포니카 벼 '아세미')

  • Jeong, Eung-Gi;kang, Kyeong-Ho;Hong, Ha-Cheol;Cho, Young-Chan;Jung, O-Young;Jeon, Yong-Hee;Chang, Jae-Ki;Lee, Jeom-Ho;Won, Yong-Jae;Yang, Un-Ho;Jung, Kuk-Hyun;Yeo, Un-Sang;Kim, Bo-Kyeong
    • Journal of the Korean Society of International Agriculture
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    • v.31 no.1
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    • pp.76-81
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    • 2019
  • 'Asemi' is a rice variety derived from a cross between 'Jinmibyeo' which has translucent milled rice and medium maturity and 'Cheolwon46', an elite line with high yield and early maturity by the rice breeding team at NICS, RDA in 2013. The heading date of 'Asemi' is August 1, six days earlier than the check variety 'Hwaseong'. It has 82 cm culm length and 109 spikelets per panicle. 'Asemi' is resistant to blast disease, stripe virus and tungro virus, but susceptible to other viruses and planthoppers. The milled rice of this variety exhibits translucent, clear non-glutinous endosperm and short grain shape. It has protein content (6.7%) higher than 'Hwaseong', and amylose content (19.5%) similar to 'Hwaseong'. The milled rice recovery rate of 'Asemi' is similar to that of 'Hwaseong'. However, the head rice rate of 'Asemi' is higher than that of 'Hwaseong'. Milled rice yield of 'Asemi' is 5.23 MT/ha in ordinary cultivation. ' Asemi' could be adaptable to the wide region of tropical Asia (Registration No. 5639).

Degradation of Poultry Feathers by Bacillus amyloliquefaciens Y10 With Plant Growth-promoting Activity and Biological Activity of Feather Hydrolyzates (식물 성장 촉진 활성을 가진 Bacillus amyloliquefaciens Y10에 의한 가금 우모의 분해 및 생산된 우모 분해산물의 생리활성)

  • Yedam Kim;Young Seok Lee;Youngsuk Kim;Jinmyeong Song;Yeongbeen Bak;Gyulim Park;O-Mi Lee;Hong-Joo Son
    • Journal of Life Science
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    • v.34 no.5
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    • pp.304-312
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    • 2024
  • This study was conducted to characterize strain Y10, isolated from discarded chicken feathers. Strain Y10 was identified as Bacillus amyloliquefaciens through phenotypic and 16S rRNA gene analysis. B. amyloliquefaciens Y10 exhibited plant growth-promoting activities, including the production of fungal cell-degrading enzymes (cellulase, lipase, protease, and pectinase), siderophores, ammonia, and indoleacetic acid. Furthermore, strain Y10 was able to inhibit the mycelial growth of several phytopathogenic fungi. When 0.1% sucrose as a carbon source and 0.05% casein as a nitrogen source were added to the basal medium, adjusted to pH 10, and cultured at 35℃, the degradation rate of chicken feathers by strain Y10 was about two times higher than that of the basal medium, with the feathers almost completely degraded in four days. Strain Y10 also degraded various keratin substrates, including duck feathers, wool, and human nails. It was confirmed that the feather hydrolyzates prepared using strain Y10 exhibited antioxidant activities, such as 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity (EC50 = 0.38 mg/ml) and superoxide dismutase-like activity (EC50 = 183.7 mg/ml). These results suggest that B. amyloliquefaciens Y10 is a potential candidate for the development of bioinoculants and feed additives applicable to the agricultural and livestock industries, as well as the microbiological treatment of keratin waste.

Effectiveness of controlled atmosphere container on the freshness of exported PMRsupia melon (CA 컨테이너를 이용한 수출 멜론의 선도유지 효과)

  • Haejo Yang;Min-Sun Chang;Puehee Park;Hyang Lan Eum;Jae-Han Cho;Ji Weon Choi;Sooyeon Lim;Yeo Eun Yun;Han Ryul Choi;Me-Hea Park;Yoonpyo Hong;Ji Hyun Lee
    • Food Science and Preservation
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    • v.30 no.5
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    • pp.822-832
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    • 2023
  • This study investigates the effectiveness of CA (controlled atmosphere) containers in maintaining the freshness of exported melons. The melons were harvested on June 5, 2023, in the Yeongam area of Jeollanam-do, Korea. The CA container was loaded with melon samples packed in an export box. The temperature inside the container was set at 4℃, while the gas composition was set at 5% oxygen, 12% carbon dioxide, and 83% nintrogen. Following two weeks of simulated transportation, quality analysis was conducted at 10℃. The melons were inoculated with spore suspensions, and the decay rate was determined to investigate the effect of the gas composition inside the CA container on suppressing the occurrence of Penicillium oxalicum in melons. The results were compared with a Reefer container set at the same temperature. The samples transported in the CA container exhibited lower weight loss. The melon pulp softening, respiration rate, and ethylene production were slower using the CA container. Moreover, the decay rate during the distribution period in the CA container was lower than in the Reefer container. In contrast, the firmness of melons transported in the Reefer container decreased significantly (from 9.03N to 5.18N) immediately after transportation. The soluble solid content (SSC) of melons transported in the Reefer container also decreased rapidly. The results suggested that the CA container is the optimal export container for maintaining the freshness of melons.

Preference and Sensory Trait Analysis of Korean Rice Varieties among International Consumers (해외소비자의 국내육성 벼 품종에 대한 선호도 및 식미관련 형질 분석)

  • Chang-Min Lee;Song-Hee Park;Su-Kyung Ha;Hyun-Sook Lee;Gileng Lee;Seung Young Lee;Ji-Ung Jeung;Hyun-Su Park;Jae-Ryoung Park;O-Young Jeong
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.68 no.4
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    • pp.262-275
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    • 2023
  • This study aimed to assess the preferences of African, American, and Asian panels, in comparison to a Korean panel, for various Korean rice varieties, including three japonica, two indica, and one Tongil-type, all developed by the Rural Development Administration in Korea. Regarding rice appearance, most panelists, except for the Koreans, favored long and slender rice varieties like 'Hanyeol', 'Hyangyeol', and 'Amissal'. In contrast, the Koreans preferred wider varieties like 'Sindongjin' and 'Deuraehyang'. Notably, the overseas panelists consistently favored rice varieties with high appearance quality in sensory evaluations of cooked rice. Both overseas and Korean panelists strongly preferred the indica rice variety 'Hanyeol' in terms of appearance quality and sensory evaluations. However, Korean rice varieties like 'Amissal' and 'Sindongjin' scored high in appearance quality with overseas panelists but received low ratings in sensory aspects, including shape, stickiness, and taste, compared to those for 'Hanyeol'. This suggests that considering sensory characteristics is important when exporting Korean rice varieties. Regarding taste characteristics preferred by the panelists derived from the correlation analysis between taste traits, Africans preferred rice with a smooth texture and no stickiness, especially favoring long-grain rice. Americans leaned towards rice with a slightly firm texture, some stickiness, and late aging characteristics. Asians preferred rice with a smooth texture, low stickiness, and long-grain varieties. In contrast, Koreans favored round rice with a glossy appearance, a slightly firm texture, late aging traits, and some stickiness. These research findings can serve as valuable data for the development of rice varieties for overseas markets and are expected to contribute to securing competitiveness in international markets.

The Effect of Users' Personality on Emotional and Cognitive Evaluation in UCC Web Site Usage (UCC(user-created-contents) 웹 사이트에서 사용자의 인성이 감정적, 인지적 평가와 UCC 활용에 미치는 영향)

  • Moon, Yun-Ji;Kang, So-Ra;Kim, Woo-Gon
    • Asia pacific journal of information systems
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    • v.20 no.3
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    • pp.167-190
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    • 2010
  • The research conducted here focuses on the effect of factors that affect the behavior of UCC (User Created Content) website users, other than user's rational recognition of how useful a UCC website can be. Most discussions in the existing literature on information systems have focused on users' evaluation how a UCC website can help to attain the users' own goals. However, there are other factors and this research pays attention to an individual's 'personality,' which is stable and biological in nature. Specifically, I have noted here that 'extroversion' and 'neuroticism,' the two common personality factors presented in Eysenck's most representative 'EPQ Model' and 'Big Five Model,' are the two personality factors that affect a site's 'usefulness,' by this I mean how useful does the user consider the website and its content. How useful a site is considered by the user is the other factor that has been regarded as the antecedent factor that influences the adoption of information systems in the existing MIS (Management Information System) research. Secondly, as using or creating a UCC website does not guarantee the user's or the creator's extrinsic motivation, unlike when using the information system within an organization, there is a greater likelihood that the increase in user's activities in relation to a UCC website is motivated by emotional factors rather than rational factors. Thus, I have decided to include the relationship between an individual's personality and what they find pleasurable in the research model. Thirdly, when based on the S-O-R Paradigm of Mehrabian and Russell, the two cognitive factors and emotional factors are finally affected by stimulus, and thus these factors ultimately have an effect on an individual's respondent behavior. Therefore, this research has presented an assumption that the recognition of how useful the site and content is and what emotional pleasure it provides will finally affect the behavior of the UCC website users. Finally, the relationship between the recognition of how useful a site is and how pleasurable it is to useand UCC usage may differ depending on certain situational conditions. In other words, the relationship between the three factors may vary according to how much users are involved in the creation of the website content. Creation thus emerges as the keyword of UCC. I analyzed the above relationships through the moderating variable of the user's involvement in the creation of the site. The research result shows the following: When it comes to the relationship between an individual's personality and what they find pleasurable it is extroverted users who have a greater likelihood to feel pleasure when using a UCC website, as was expected in this research. This in turn leads to a more active usage of the UCC web site because a person who is an extrovert likes to spend time on activities with other people, is sensitive to new experiences and stimuli and thus actively responds to these. An extroverted person accepts new UCC activities as part of his/her social life, rather than getting away from this new UCC environment. This is represented by the term 'Foxonomy' where the users meet a variety of users from all over the world and contact new types of content created by these users. However, neuroticism creates the opposite situation to that created by extroversion. The representative symptoms of neuroticism are instability, stress, and tension. These dispositions are more closely related to stress caused by a new environment rather than this creatingcuriosity or pleasure. Thus, neurotic persons have an uneasy feeling and will eventually avoid the situation where their own or others' daily lives are frequently exposed to the open web environment, this eventually makes them have a negative attitude towards the web environment. When it comes to an individual's personality and how useful site is, the two personality factors of extroversion and neuroticism both have a positive relationship with the recognition of how useful the site and its content is. The positive, curious, and social dispositions of extroverted persons tend to make them consider the future usefulness and possibilities of a new type of information system, or website, based on their positive attitude, which has a significant influence on the recognition of how useful these UCC sites are. Neuroticism also favorably affects how useful a UCC website can be through a different mechanism from that of extroversion. As the neurotic persons tend to feel uneasy and have much doubt about a new type of information system, they actively explore its usefulness in order to relieve their uncomfortable feelings. In other words, neurotic persons seek out how useful a site can be in order to secure their own stable feelings. Meanwhile, extroverted persons explore how useful a site can be because of their positive attitude and curiosity. As a lot of MIS research has revealed that the recognition of how useful a site can be and how pleasurable it can be to use have been proven to have a significant effect on UCC activity. However, the relationship between these factors reveals different aspects based on the user's involvement in creation. This factor of creationgauges the interest of users in the creation of UCC contents. Involvement is a variable that shows the level of an individual's mental effort in creating UCC contents. When a user is highly involved in the creation process and makes an enormous effort to create UCC content (classed a part of a high-involvement group), their own pleasure and recognition of how useful the site is have a significantly higher effect on the future usage of the UCC contents, more significantly than the users who sit back and just retrieve the UCC content created by others. The cognitive and emotional response of those in the low-involvement group is unlikely to last long,even if they recognize the contents of a UCC website is pleasurable and useful to them. However, the high-involvement group tends to participate in the creation and the usage of UCC more favorably, connecting the experience with their own goals. In this respect, this research presents an answer to the question; why so many people are participating in the usage of UCC, the representative form of the Web 2.0 that has drastically involved more and more people in the creation of UCC, even if they cannot gain any monetary or social compensation. Neither information system nor a website can succeed unless it secures a certain level of user base. Moreover, it cannot be further developed when the reasons, or problems, for people's participation are not suitably explored, even if it has a certain user base. Thus, what is significant in this research is that it has studied users' respondent behavior based on an individual's innate personality, emotion, and cognitive interaction, unlike the existing research that has focused on 'compensation' to explain users' participation with the UCC website. There are also limitations in this research. Firstly, I divided an individual's personality into extroversion and neuroticism; however, there are many other personal factors such as neuro-psychiatricism, which also needs to be analyzed for its influence on UCC activities. Secondly, as a UCC website comes in many types such as multimedia, Wikis, and podcasting, these types need to be included as a sub-category of the UCC websites and their relationship with personality, emotion, cognition, and behavior also needs to be analyzed.

THE EFFECT OF ND:YAG LASER IRRADIATION ON THE FORMATION OF CALCIUM FLUORIDE AND ACID RESISTANCE OF TOOTH ENAMEL (Nd:YAG 레이저 조사가 Calcium Fluoride 형성 및 치아 내산성에 미치는 영향)

  • Lee, Jae-Ho;Sohn, Heung-Kyu;Kim, Seong-Oh;Park, Kwang-Kyun;Choi, Byung-Jai
    • Journal of the korean academy of Pediatric Dentistry
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    • v.26 no.2
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    • pp.377-398
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    • 1999
  • Calcium fluoride, created by topical fluoride application, is the reservoir for fluoride ion regulated by pH in the oral environment. Therefore, the amount and the maintenance of calcium fluoride have an important role in preventing dental caries. The aim of this study is to evaluate the effect of Nd:YAG laser irradiation on the generation of calcium fluoride and the acid resistance of tooth enamel. The bovine anterior permanent teeth were prepared (n=276), and divided into following groups : no treatment (control) fluoride application alone, laser irradiation alone, laser irradiation after fluoride application, and fluoride application after laser irradiation. And each group was subdivided based on the application time of 1.23% acidulated phosphate fluoride (APF) (5 min and 30 min) and the irradiation energy of Nd:YAG laser ($20J/cm^2\;and\;40J/cm^2$). In case of fluoride application, each group was divided according to KOH treatment. Twenty three treatment conditions were made for this experiment and twelve specimens were assigned to each treatment condition. In each treatment condition, ten specimens were used for chemical analysis and two specimens were observed under SEM. In groups without treating KOH, fluoride content and the depth of enamel dissolved were measured using enamel biopsy technique. In groups with treating KOH, the amount of calcium fluoride was measured by the treatment with 1 M KOH for 24 hours and enamel biopsy was performed after KOH treatment. The results were analyzed by the fluoride content and the depth of enamel dissolved by enamel biopsy, amount and thickness of calcium fluoride, and the surface structures of enamel. The results are as follows: 1. In groups without treating KOH, the fluoride content of removed enamel showed a positive relationship with the energy density of laser when the laser irradiated before fluoride application 2. In groups without treating KOH, the depth of enamel dissolved decreased more with the combined laser and fluoride treatment than with laser or fluoride treatment, except for the case of $20J/cm^2$ laser irradiation after 5 minute fluoride application (p<0.05). 3. The amount of calcium fluoride did not increased by laser treatment with no statistical significance(p>0.05). 4. The particle size of calcium fluoride increased in case of fluoride treatment after laser irradiation, compared with fluoride application alone. In case of laser treatment after fluoride application, the particle size of calcium fluoride increased and some of the particles fused as well. 5. There were no significant differences in the fluoride content of dissolved enamel between groups without treating KOH and control group, except for the case of laser irradiation after treatment of APF for 30 minutes (p>0.05). 6. In groups with treating KOH, depth of removed enamel in the groups of combined treatment with laser and fluoride was shallower than that in fluoride application groups (p<0.05). 7. In groups without treating KOH, the relationship between fluoride content and the depth of enamel dissolved showed more negative (Spearman correlation coefficient: -0.6281) than in groups with treating KOH (Spearman correlation coefficient: -0.3792). The greater amount of calcium fluoride could be found in case where there was a significant differences of the depth of enamel dissolved between groups with and without treating KOH. From these results, it can be concluded that laser seems to be a little effects on the amount of calcium fluoride formation, but has some effect on the lowering the solubility of calcium fluoride. As the combined treatment of laser and fluoride application showed more effective acid-resistant property, more extended recall period for fluoride application can be achieved with this combined treatment in the clinic.

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