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Biological stability of Zirconia/Alumina composite ceramic Implant abutment (지르코니아/알루미나 복합 지대주의 생물학적 안정성에 관한 연구)

  • Bae, Kyu-Hyun;Han, Jung-Suk.;Kim, Tae-Il;Seol, Yang-Jo;Lee, Yong-Moo;Ku, Young;Cho, Ki-Young;Chung, Chong-Pyoung;Han, Soo-Boo;Rhyu, In-Chul
    • Journal of Periodontal and Implant Science
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    • v.36 no.2
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    • pp.555-565
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    • 2006
  • The purpose of the present study is to evaluate the biological stability of the zirconia/alumina composite abutment by histologic and radiographic examination in clinical cases. 17 partially edentulous patients (5 men and 12 women, mean age 47) were treated with 37 implants. The implants were placed following the standard two-stage protocol. After a healing period of 3 to 6 months, zirconia/alumina composite abutments were connected. All radiographs were taken using paralleling technique with individually fabricated impression bite block, following insertion of the prosthesis and at the 3-, 6-, 12 month re-examinations. After processing the obtained images, the osseous level was calculated using the digital image in the mesial and distal aspect in each implant. An ANOVA and t-test were used to test for difference between the baseline and 3-, 6-, 12 months re-examinations, and for difference between maxilla and mandible. Differences at P <0.05 were considered statistically significant. For histologic examination, sample was obtained from the palatal gingiva which implant functioned for 12 months. Sections were examined under a light microscope under various magnifications. Clinically, no abutment fracture or crack as well as periimplantitis was observed during the period of study. The mean bone level reduction(${\pm}standard$ deviation) was 0.34 rom(${\pm}\;0.26$) at 3-months, 0.4 2mm(${\pm}\;0.30$) at 6-months, 0.62 mm(${\pm}\;0.28$) at 12-months respectively. No statistically significant difference was found between baseline and 3-, 6-, 12-months re-examinations (p > 0.05). The mean bone level reduction in maxilla was 0.33(${\pm}0.25$) at 3-months, 0.36(${\pm}0.33$) at 6-months, 0.56(${\pm}0.26$) at 12-months. And the mean bone level reduction in mandible was 0.35(${\pm}0.27$) at 3-months, 0,49(${\pm}0.27$) at 6-months, 0.68(${\pm}0.30$) at 12-months. No statistical difference in bone level reduction between implants placed in the maxilla and mandible. Histologically, the height of the junctional epithelium was about 2.09 mm. And the width was about 0.51 mm. Scattered fibroblasts and inflammatory cells, and dense collagen network with few vascular structures characterized the portion of connective tissue. The inflammatory cell infiltration was observed just beneath the apical end of junctional epithelium and the area of direct in contact with zirconia/alumina abutment. These results suggest the zirconia/alumina composite abutment can be used in variable intraoral condition, in posterior segment as well as anterior segment without adverse effects.

Effect of specimen preparation method on the microtensile bond strength of veneering ceramic to zirconia (시편 제작 방법이 지르코니아 코어와 비니어링 세라믹의 미세 인장결합강도에 미치는 영향)

  • Kim, Ki-Yeon;Yeo, In-Sung;Kim, Sung-Hun;Han, Jung-Suk;Lee, Jai-Bong;Yang, Jae-Ho
    • The Journal of Korean Academy of Prosthodontics
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    • v.49 no.2
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    • pp.114-119
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    • 2011
  • The aim of this study was to investigate effect of specimen preparation method on the microtensile bond strength of veneering ceramic to zirconia core. Materials and methods: Cylindrical Lava zirconia block (3M ESPE, Seefeld, Germany) was cut into discs using a diamond disc. After sintering, the core specimens were placed in an adjustable mold and veneered with Lava ceram (3M ESPE, Seefeld, Germany). The disc shaped specimen of group 1 was cut into microbars ($1{\times}1{\times}7\;mm^3$) using a low speed diamond disc under water cooling (n = 15). The specimen of group 2 was cut into microbars ($1.2{\times}1.2{\times}7\;mm^3$) in the same way. Whereafter the microbars were trimmed ($1{\times}1{\times}7\;mm^3$) using a thick diamond disc under water cooling (n = 15). The microtensile bond strength was tested in a microtensile tester (Instron 8848, $Instron^{(R)}$ Co., Norwood, USA). Fractured microtensile specimens were analyzed under a stereomicroscope (MZ6, Leica Microsystems GmbH, Wetzlar, Germany) at magnification ${\times}30$. Results: The microtensile bond strength of group 1 ($28.8{\pm}7.0\;MPa$) was significantly higher than group 2 ($11.0{\pm}33\;MPa$) (P=.00). Conclusion: It appears advisable to avoid the trimming action, especially high strength ceramic specimens.

A Three-year Study on the Leaf and Soil Nitrogen Contents Influenced by Irrigation Frequency, Clipping Return or Removal and Nitrogen Rate in a Creeping Bentgrass Fairway (크리핑 벤트그라스 훼어웨이에서 관수회수.예지물과 질소시비수준이 엽조직 및 토양 질소함유량에 미치는 효과)

  • 김경남;로버트쉬어만
    • Asian Journal of Turfgrass Science
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    • v.11 no.2
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    • pp.105-115
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    • 1997
  • Responses of 'Penncross' creeping bentgrass turf to various fairway cultural practices are not well-established or supported by research results. This study was initiated to evaluate the effects of irrigation frequency, clipping return or removal, and nitrogen rate on leaf and soil nitrogen con-tent in the 'Penncross' creeping bentgrass (Agrostis palustris Huds.) turf. A 'Penncross' creeping bentgrass turf was established in 1988 on a Sharpsburg silty-clay loam (Typic Argiudoll). The experiment was conducted from 1989 to 1991 under nontraffic conditions. A split-split-plot experimental design was used. Daily or biweekly irrigation, clipping return or removal, and 5, 15, or 25 g N $m-^2$ $yr-^1$ were the main-, sub-, and sub-sub-plot treatments, respectively. Treatments were replicated 3 times in a randomized complete block design. The turf was mowed 4 times weekly at a l3 mm height of cut. Leaf tissue nitrogen content was analyzed twice in 1989 and three times in both 1990 and 1991. Leaf samples were collected from turfgrass plants in the treatment plots, dried immediately at 70˚C for 48 hours, and evaluated for total-N content, using the Kjeldahl method. Concurrently, six soil cores (18mm diam. by 200 mm depth) were collected, air dried, and analyzed for total-N content. Nitrogen analysis on the soil and leaf samples were made in the Soil and Plant Analyical Laboratory, at the University of Nebraska, Lincoln, USA. Data were analyzed as a split-split-plot with analysis of variance (ANOVA), using the General Linear Model procedures of the Statistical Analysis System. The nitrogen content of the leaf tissue is variable in creeping bentgrass fairway turf with clip-ping recycles, nitrogen application rate and time after establishment. Leaf tissue nitrogen content increased with clipping return and nitrogen rate. Plots treated with clipping return had 8% and 5% more nitrogen content in the leaf tissue in 1989 and 1990, respectively, as compared to plots treated with clipping removal. Plots applied with high-N level (25g N $m-^2$ $yr-^1$)had 10%, 17%, and 13% more nitrogen content in leaf tissue in 1989, 1990, and 1991, respectively, when compared with plots applied with low-N level (5g N $m-^2$ $yr-^1$). Overall observations during the study indicated that leaf tissue nitrogen content increased at any nitrogen rate with time after establishment. At the low-N level treatment (5g N $m-^2$ $yr-^1$ ), plots sampled in 1991 had 15% more leaf nitrogen content, as compared to plots sampled in 1989. Similar responses were also found from the high-N level treatment (25g N $m-^2$ $yr-^1$ ).Plots analyzed in 1991 were 18% higher than that of plots analyzed in 1989. No significant treatment effects were observed for soil nitrogen content over the first 3 years after establishment. Strategic management application is necessary for the golf course turf, depending on whether clippings return or not. Different approaches should be addressed to turf fertilization program from a standpoint of clipping recycles. It is recommended that regular analysis of the soil and leaf tissue of golf course turf must be made and fertilization program should be developed through the interpretation of its analytic data result. In golf courses where clippings are recycled, the fertilization program need to be adjusted, being 20% to 30% less nitrogen input over the clipping-removed areas. Key words: Agrostis palustris Huds., 'Penncross' creeping bentgrass fairway, Irrigation frequency, Clipping return, Nitrogen rate, Leaf nitrogen content, Soil nitrogen content.

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Effect of Seeding Dates of Italian Ryegrass Interseeded into Bermudagrass Sod on the Forage Productivity and Botanical Composition of Italian Ryegrass and Bermudagrass (버뮤다그라스 초지에 보파한 이탈리안 라이그라스의 파종시기가 목초생산성과 식생에 미치는 영향)

  • Park, Nam-Geon;Hwang, Kyung-Jun;Lee, Chong-Eon;Kim, Nam-Young;Park, Hyung-Soo;Ko, Moon-Suk;Lim, Young-Cheol
    • Journal of The Korean Society of Grassland and Forage Science
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    • v.31 no.4
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    • pp.383-388
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    • 2011
  • This study was carried out to determine the effect of seeding dates of Italian ryegrass interseeded into bermudagrass sod on the forage productivity and botanical composition of Italian ryegrass and bermudagrass. Experimental plot was located at 200 m altitude within Subtropical Animal Experiment Station, National Institute of Animal Science in Jeju from 2009 to 2010. Seeding date treatments of Italian ryegrass into bermudagrass sod were arranged in a randomized complete block design replicated three times. Italian ryegrass was drilled in row 20 cm apart after clipping the bermudagrass at a cutting height of 2~3 cm. Seeding time was on 15 September, 30 September and 15 October. The dry matter yield of Italian ryegrass was higher in 15 September seeding treatment, the dry matter yields of 30 September and 15 October seeding treatment were not different. The Italian ryegrass interseeded into bermudagrass sod didn't affect the dry matter yield in the summer harvests of bermudagrass, and the dry matter yield of bermudagrass showed the highest in August. In botanical composition, Italian ryegrass showed to reduced growth in early seedling stage after seeding by competition with bermudagrass, but Italian ryegrass was dominant to June increasing of temperature in spring next year and bermudagrass after Italian ryegrass harvests was dominant during summer season.

Effects of Harvest Stage on Agronomic Characteristics, Yield and Feed Value of Silage Corn in the Newly Reclaimed Hilly Land (산지 신개간 토양에서 사료용 옥수수 수확시기가 생육특성, 생산성 및 사료가치에 미치는 영향)

  • Do, Gu-Ho;Kim, Eun-Joong;Lee, Sang-Moo
    • Journal of The Korean Society of Grassland and Forage Science
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    • v.32 no.3
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    • pp.253-264
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    • 2012
  • This study was carried out to investigate growth characteristics, yield, chemical compositions and nutrients yield of corn hybrids for silage in the newly reclaimed hilly land. The experimental design was arranged in a randomized block design with three replications. The seeding time was at May 6. The harvest time of four treatments was milk stage (97 days), dough stage (105 days), yellow stage (112 days) and late yellow stage (119 days after seeding). Plant height, ear height, leaf numbers and ear length were highest in yellow stage (p<0.05, 0.01), but dead leaf, stem hardness and sugar degree (Brix) were higher in late yellow than other treatments. Leaf width, tip filling degree and fresh yield were not significantly different. Dry matter yield increased as the maturity stage progressed (p<0.01). Crude protein and crude fat were not significantly different. NDF and ADF decreased as the maturity stage progressed (p<0.01). Ca content was the highest at milk stage (p<0.05), Fe and P were the highest at dough stage (p<0.05, 0.01). However another minerals were not significantly different. Essential amino acid (EAA), nonessential amino acid (NEAA) and total amino acid were highest at yellow stage, but no significant differences were found among the treatments. Total free sugar contents were higher in the order of Milk > dough > yellow > late yellow stage, but no significant differences were found among the treatments. Crude protein yield was the highest at yellow stage, but crude fat yield, amino acid yield and TDN yield were highest at late yellow stage (p<0.01). Total mineral yield showed no significant difference. Based on the above results, yellow and late yellow stage compared to other maturity stage have been shown to increase dry matter yield and nutrients yield, when silage corn grow cultivate in the newly reclaimed hilly land.

Palatability and Yield of Winter Annual Forage Crops under Horse Grazing System in Jeju (제주지역 말 방목체계에서 동계사료작물의 말 기호성 및 생산성)

  • Park, Nam Geon;Woo, Jae Hoon;Yoo, Ji hyun;Shin, Sang-Min;Park, Hyung Soo;Hwang, Won-Uk
    • Journal of The Korean Society of Grassland and Forage Science
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    • v.40 no.2
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    • pp.106-110
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    • 2020
  • The purpose of this study was to evaluate winter annual forage crops for yield, and horse palatability under horse grazing during the fall and spring in Jeju. The winter annual forage crops such as Italian ryegrass(IRG), rye, and oat were planted in randomized block design in October 30. The horse grazing was initiated on March 17 of the following year. At the first cutting, the dry matter yield of rye was the highest with 4,600 kg/ha compared to the IRG and oat (p<0.05). But there were no significantly different in the yield of winter annual forage crops after the second and third harvests. The total dry matter yield showed rye 12,593 kg/ha, IRG 10,941 kg/ha, and oat 9,424 kg/ha respectively. The horse intake duration of the IRG was significantly higher than the oat and rye (p<0.05). In the first grazing and the second grazing, the intake duration of the IRG was 853.2 seconds and 989.4 seconds, respectively, with oat at 147.6 seconds, and 73.0 seconds, and rye at 89.4 seconds, and 33.18 seconds. The intake duration of IRG was longer than that of oat and rye (p<0.05). The intake rate of the IRG was 60.0% in the first and 82.8% in the second, and the average intake rate was 71.4%. When considering the maintenance of pastures and the palatability of horses, the IRG is the most suitable forage crop in winter annual forage crops in Jeju.

Activation of Pro-Apoptotic Multidomain Bcl-2 Family Member Bak and Mitochondria-Dependent Caspase Cascade are Involved in p-Coumaric Acid-Induced Apoptosis in Human Jurkat T Cells (p-Coumaric acid에 의해 유도되는 인체 Jurkat T 세포의 에폽토시스 기전)

  • Lee, Je-Won;Kim, Young-Ho
    • Journal of Life Science
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    • v.21 no.12
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    • pp.1678-1688
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    • 2011
  • The apoptogenic effect of p-coumaric acid, a phenolic acid found in various edible plants, on human acute leukemia Jurkat T cells was investigated. Exposure of Jurkat T cells to p-coumaric acid (50-$150{\mu}M$) caused cytotoxicity and TdT-mediated dUTP nick-end labeling (TUNEL)-positive apoptotic DNA fragmentation along with Bak activation, ${\Delta}{\psi}m$ loss, activation of caspase-9, -3, -7, and -8, and PARP degradation in a dose-dependent manner. However,these apoptotic events were completely abrogated in Jurkat T cells overexpressing Bcl-2.Under these conditions, necrosis was not accompanied. Pretreatment of the cells with the pan-caspase inhibitor (z-VAD-fmk) could prevent p-coumaric acid-induced sub-$G_1$ peak representing apoptotic cells, whereas it failed to block ${\Delta}{\psi}m$ loss, indicating that the activation of caspase cascade was prerequisite for p-coumaric acid-induced apoptosis as a downstream event of ${\Delta}{\psi}m$ loss. FADD- and caspase-8-positive wild-type Jurkat T cell clone A3, FADD-deficient Jurkat T cell clone I2.1, and caspase-8-deficient Jurkat T cell clone I9.2 exhibited similar susceptibilities to the cytotoxicity of p-coumaric acid, excluding an involvement of Fas/FasL system in triggering the apoptosis. The apoptogenic activity of p-coumaric acid is more potent in malignant Jurkat T cells than in normal human peripheral T cells. Together, these results demonstrated that p-coumaric acid-induced apoptogenic activity in Jurkat T cellswas mediated by Bak activation, ${\Delta}{\psi}m$ loss, and subsequent activation of multiple caspases such as caspase-9, -3, -7, and-8, and PARP degradation, which could be regulated by anti-apoptotic protein Bcl-2.

Effects of Planting Density on Growth and Yield in Cassia obtusifolia. L. (결명자(決明子)의 재식밀도(栽植密度)가 생육(生育) 및 수량(收量)에 미치는 영향(影響))

  • Kim, Young-Guk;Bang, Jin-Ki;Yu, Hong-Seob;Lee, Seoung-Tack;Park, Jong-Sun
    • Korean Journal of Medicinal Crop Science
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    • v.5 no.2
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    • pp.95-101
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    • 1997
  • This study was conducted to investigate how a labor saving for conventional hand sowing and respond to major agronomic traits under different planting density in 1993 and 1994. Each trial was a randomized block split plot with row spacing as the main plots and hill spacing as subplots. Sowing rate appeared lower in 20 or 25cm hill spacing using machine seeder than in hand sowing. Sowing time required reduced more 121 hours per hectare in 60cm row, 20cm hill spacings using machine seeder than in hand sowing. Increasing row and hill spacings reduced number of seedling stand per unit $area(m^2)$. Both number of pods per plant and grain weight per plant and showed highly increase in wide planting. Best yield obtained in 60cm row, 20cm hill spacing using machine seeder. Accumulative mean air temperature was positively correlated with stem height, number of pods per plant and yield, otherwise accumulative rainfall was negatively correlated with ones. A highly significant negative correlation was showed between number of seedling stand per unit $area(m^2)$ and number of branches, number of pods per plant, grain weight per plant and yield. Yield was positively correlated with number of branches, number of pods per plant and grain weight per plant.

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EFFECT OF INTERMITTENT POLYMERIZATION ON THE RATE OF POLYMERIZATION SHRINKAGE AND CUSPAL DEFLECTION IN COMPOSITE RESIN (복합 레진의 간헐적 광중합 방법이 중합 수축 속도와 치아의 교두 변위에 미치는 영향)

  • Kim, Min-Kyung;Park, Sung-Ho;Seo, Deog-Gyu;Song, Yun-Jung;Lee, Yoon;Lee, Chan-Young
    • Restorative Dentistry and Endodontics
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    • v.33 no.4
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    • pp.341-351
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    • 2008
  • This study investigated the effect of intermittent polymerization on the rate of polymerization shrinkage and cuspal deflection in composite resins. The linear polymerization shrinkage of each composite was measured using the custom-made linometer along with the light shutter specially devised to block the light at the previously determined interval. Samples were divided into 4 groups by light curing method; Group 1) continuous light (60s with light on); Group 2) intermittent light (cycles of 3s with 2s light on & 1s with light off for 90s): Group 3) intermittent light (cycles of 2s with 1s light on & 1s with light off for 120s); Group 4) intermittent light (cycles of 3s with 1s light on & 2s with light off for 180s). The amount of linear polymerization shrinkage was measured and its maximum rate (Rmax) and peak time (PT) in the first 15 seconds were calculated. For the measurement of cuspal deflection of teeth, MOD cavities were prepared in 10 extracted maxillary premolars. Reduction in the intercuspal distance was measured by the custom-made cuspal deflection measuring machine. ANOVA analysis was used for the comparison of the light curing groups and t-test was used to determine significant difference between the composite resins. Pyramid showed the greater amount of polymerization shrinkage than Heliomolar (p < 0.05). There was no significant difference in the linear polymerization shrinkage among the groups. The Rmax was group 4 < 3, 2 < 1 in Heliomolar and group 3 < 4 < 2, 1 in Pyramid (p < 0.05). Pyramid demonstrated greater cuspal deflection than Heliomolar. The cuspal deflection in Heliomolar was group 4 < 3 < 2, 1 and group 4, 3 < 2, 1 in Pyramid (p < 0.05). It was concluded that the reduced rate of polymerization shrinkage by intermittent polymerization can help to decrease the cuspal deflection.

Physical Geography of Munkyung (문경의 자연지리)

  • Bak, Byeong-Su;Son, Myoung-Won
    • Journal of the Korean association of regional geographers
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    • v.4 no.2
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    • pp.15-30
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    • 1998
  • Physical geography is the discipline which deals with the relationship between man and natural environment. Therefore, it should be studied as the organized unity. In this paper I recognize the drainage basin as a framework outlining physical geography, describe the difference of inhabitant's life style due to the difference of natural environment in the drainage basin, and consider the meaning of drainage basin as a unit of life(and unit of regional geography). Munkyung is divided into three regions(intermontane basin region, middle mountainous region, marginal hilly region of the great basin) owing to the topographic characteristics. Subdivision in these regions is related closely to drainage network distribution, specially in intermontane basin region. And small regions have developed with the confluence point of $3{\sim}4$ order streams as the central figure. Intermontane basin region is the valley floor of Sinbuk-Soya-Kauun-Nongam stream located in the limestone region which is exposed according to Munkyung fault at its northern part. Small streams are affected strongly by the influence of the NNE-SSE or WNW-ESE tectolineament. Thus Kaeripryungro(鷄立嶺路), Saejaegil(새재길), Ewharyungro(伊火嶺路) and so on are constructed through the tectolineament. In the valley floors of small streams which flow into the intermontane basin, there are large floodplains. Floodplain in Sinbuk, Joryung, and Yangsan stream is used to paddy field or orchard, and in Nongam stream is used to paddy field or vegetable field. Hills are distributed largely in the periphery of intermontane basin. Limestone hills in Kauun and Masung basin are not continuous to the present low and flat floodplain, and most of those are used to forest land and field. On the other side. granite hills in Koyori are continuous to be used to the present floodplain, and they are used to residential area and field. In the middle mountainous region are there hilly mountains constructed in the geology of Palaeozoic Pyeongan System in northern area and Chosun System's Limestone Series in southern area, and banded gneiss and schist among Sobaeksan Gneiss Complex. In Palaeozoic Pyeongan System region are there relatively rugged mountains and ingrown meanders developed along tectolineaments. Chosun System's Limestone Series region builds up a geomorphic surface, develops various karst landforms. Mountainous area is used to field. On the other hand, especially in case of Hogye, valley bottom is wide, long, and discontinuous to slope, is used to paddy field dominantly. And schist region in Youngnam Block of Pre-Cambrian is rugged mountainous. Marginal hilly region of the great basin is hilly zone located in the margin of erosional basin(Bonghwa-Youngju-Yechon-Hamchang-Sangju). This region is lower geomorphic surface which is consisted of hills of $50{\sim}100$m height. Hills are used to field or orchard, and dissected gentle depression is used to paddy field.

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