• Title/Summary/Keyword: tension pressure

Search Result 633, Processing Time 0.028 seconds

A Study on the Expression of Glycosaminoglycans in the Experimental Tooth Movement of Rat and in Cultured Periodontal Ligament Cells (실험적 치아이동시 glycosaminoglycan의 발현에 관한 연구)

  • Lee, Kyung-Hwan;Lee, Jong-Jin;Kang, Kyung-hwa;Kim, Eun-Cheol;Kim, Sang-Cheol
    • The korean journal of orthodontics
    • /
    • v.31 no.4 s.87
    • /
    • pp.447-458
    • /
    • 2001
  • The purpose of this study was to evaluate 1) in vivo, the expression of chondroitin 4-sulfate (CH-4S), a structural element of glycosaminoglycans(GAGs), in periodontal tissue during the experimental movement of rat incisors, by labelled streptavidine biotin immunohistochemical staining for CH-4S, 2) In vitro, the expression of CH-4S in cultured human periodontal ligament(PDL) cells supplemented with 10ng/ml of $TGF-{\beta}_1$, 20ng/ml of PDGF-BB, 1ng/ml $TNF-\alpha$, or $1{\mu}g/ml$ LPS by western blot analysis. The results of this study were as follows ; 1. The expression of CH-4S was stronger in pulp, PDL, osteoblasts, osteoclasts and osteocytes in experimental group than in control group, but was rare in dentin, and cementum of experimental groups, regardless of the duration of force application, which was not different from that of control group. 2. In experimental group, the expression of CH-4S in pulp began to increase at 1 day after force application and got to the highest degree at 7 days. After 14 days, the expression in CH-4S immunoreactivity was decreased, and became similar to that of control group at 28 days. 3. The expression of CH-4S in PDL was noted in adjacent to alveolar bone. PDL showed higher intensity of immunolabelling after 1 day of orthodontic tooth movement. And the expression was more stronger in the tension side than that of pressure side of PDL at 1 day, but more stronger in the pressure side than that of tension side of PDL at 4 days. After 7 days, a decrease in CH-4S expression was observed. 4. The expression of CH-4S in alveolar bone got to the highest degree at 4 days, and At 7 days, a decrease in CH-4S expression was observed. 5. PDGF-BB notably raised the expression of CH-4S in the PDL cells at 3 days of cultivation 6. The expression of CH-4S of PDL cells was decreased with the application of $TNF-\alpha$ at 1 day. 7. Admixture of $TGF-{\beta}_1$ and PDGF-BB got more expression of CH-4S in PDL as compared to only $TGF-{\beta}1$ or PDGF-BB. A similar decrease of the expression of CH-4S was observed in the case of application of LPS or $TNF-\alpha$.

  • PDF

The Effects of Estrogen on Experimental Tooth Movement in Ovariectomized Rats (난소적출 백서에서 estrogen투여가 실험적 치아이동에 미치는 영향)

  • Jin, Keun-Ho;Kim, Jong-Ghee;Park, Byung-Keon;Kim, Oh-Hwan
    • The korean journal of orthodontics
    • /
    • v.27 no.4 s.63
    • /
    • pp.585-597
    • /
    • 1997
  • The purpose of this study was to evaluate the effect of estrogen on the periodontium and alveolar bone tissue response during experimental tooth movement in ovariectomized rats. Eighty female rats, 250gm in body weight, were classified into four groups ; sham operated group(NN), ovariectomized group(ON), ovariectomized & estrogen injected group(OE), sham operated & estrogen injected group(NE). flats were ovariectomized before 3 weeks to begin the experiment, which resulted in estrogen-deficient osteoporosis. In OE group & NE group, estrogen was injected $50{\mu}g/kg\;B.W.$ every other days. The left maxillary 1st molar was moved mesially with 60g force. Each foot rats were sacrificed after 1, 3, 7, 15 days from application of orthodontic appliance and alter additional 7 days from removal of orthodontic appliance. Histological findings on mesial roots of upper 1st molar in pressure and tension side are observed. The results were summarized as follows ; 1. In pressure side of alveolar bone, the number of osteoclasts and Howship's lacuna of ON group was significantly more than that of NN group from 1 day to 15 days(P<0.05). Especially the number of Howship's lacuna of ON group was significantly more than that of OE group during all experimental period(P<0.05). 2. In tension side of alveolar tune, the number of osteoclasts of ON group was significantly increased from 1 day to 3 days and decreased after 7 days. But the number of osteoclast of ON group was significantly mote than that of NN group during all experimental period(P<0.05). Also the number of Howship's lacuna of all groups was abruptly increased at 1 day, but slowly decreased till experimental 15 days. And the number of Howship's lacuna of of group was significantly more than that of NN group from 0 hr to 7 days(P<0.05). 3. The speed of tooth movement of OE group & NE group was similar to that of NN group(P>0.05). The amount of tooth movement of ON group between 7 days and 15 days was significantly greater than those of other groups(P<0.05). 4. The degree of relapse of ON group after 7 days from removal of orthodontic appliance was similar to those of other groups(P>0.05).

  • PDF

Association between Snoring and Hypertension in a Rural Population (일부 농촌지역 주민의 코골이와 고혈압의 연관성)

  • Choi, Jin-Su;Rhee, Jung-Ae;Shin, Hee-Young
    • Journal of Preventive Medicine and Public Health
    • /
    • v.34 no.3
    • /
    • pp.284-290
    • /
    • 2001
  • Objectives : To evaluate the association of snoring and hyper-tension in a rural population. Methods : A population-based sample of 1,763 adults in Chonnam, Korea was investigated with questionnaires and height, weight, and blood pressure measurements. Information on the demographic characteristics, cigarette smoking, alcohol consumption, hypertension and snoring was collected through a person-to-person interview using a structured questionnaire. The level of obesity was measured by the body mass index(BMI). Hypertension was considered to be present if the average of two blood pressure measurements was greater than 140mmHg systolic or 90mmHg diastolic, or if they were currently on antihypertensive treatment. Results : The prevalence of snoring was 42.7% in men and 39.8% in women. With regard to age, snoring prevalence was 44.3% in the middle-aged group(45 to 64 years), greater than 33.9% in the younger(<45 years) group or 38.7% in the elderly($\geq65$ years) group. The snoring prevalence increased progressively with increasing BMI, but cigarette smoking and alcohol consumption was not associated with snoring. Hypertension occurred more frequently in snorers than in non-snorers (Odds ratio: 1.25, 95% confidence interval : 1.01-1.55). However after adjusting for sex, age, obesity, smoking, and alcohol use, an effect of snoring on hypertension was no longer present (Odds ratio: 1.13, 95% confidence interval = 0.90-1.41). Conclusion : These results suggest that snoring might not be associated with hypertension.

  • PDF

Nonlinear Analysis of Nuclear Reinforced Concrete Containment Structures under Accidental Thermal Load and Pressure (온도 및 내압을 받는 원자로 철근콘크리트 격납구조물의 비선형해석)

  • Oh, Byung Hwan;Lee, Myung Gue
    • KSCE Journal of Civil and Environmental Engineering Research
    • /
    • v.14 no.3
    • /
    • pp.403-414
    • /
    • 1994
  • Nonlinear analysis of RC containment structure under thermal load and pressure is presented to trace the behaviour after an assumed LOCA. The temperature distribution varying with time through the wall thickness is determined by transient finite element analysis with the two time level scheme in time domain. The layered shell finite elements are used to represent the containment structures in nuclear power plants. Both geometric and material nonlinearities are taken into account in the finite element formulation. The constitutive relation of concrete is modeled according to Drucker-Prager yield criteria in compression. Tension stiffening model is used to represent the tensile behaviour of concrete including bond effect. The reinforcing bars are modeled by smeared layer at the location of reinforcements accounting elasto-plastic axial behaviors. The steel liner model under Von Mises yield criteria is adopted to represent elastic-perfect plastic behaviour. Geometric nonlinearity is formulated to consider the large displacement effect. Thermal stress components are determined by the initial strain concept during each time step. The temperature differential between any two consecutive time steps is considered as a load incremental. The numerical results from this study reveal that nonlinear temperature gradient based on transient thermal analysis will produces excessive large displacement. Nonlinear behavior of containment structures up to ultimate stage can be traced reallistically. The present study allows more realistic analysis of concrete containment structures in nuclear power plants.

  • PDF

Fundamentals of Contact Lens Movement (콘택트렌즈 운동의 기초)

  • Kim, Dae Soo
    • Journal of Korean Ophthalmic Optics Society
    • /
    • v.13 no.1
    • /
    • pp.5-13
    • /
    • 2008
  • Purpose: This review article was written to investigate what kind of forces are acting on the contact lens fitted on the cornea and its subsequent motion. Methods: A capillary action-induced force develops in the tear layer between the lens and cornea, which leads to the restoring force due to difference in layer thickness according to lens rotation. The characteristics of the lens movement can be determined by the various factors such as friction between eyelid and lens, acceleration force based on blinking and the restoring force incorporated with the viscous damping force. A mathematical model which consists of the differential equations and their numerical solution was proposed to analyze the damped motion of lenses. The model predicts the time dependence of lenses during and after the blink varying the BC, blink period and eyelid pressure. Results: It was found that both the blink period and lid pressure increases the movement increases because of the enhanced lid friction. As the BC increases the viscous damping reduces due to the lacrimal layer's increase which resulted in the enhanced lens motion. After blink the lens illustrates the damped oscillation because of the restoring force by the increased lacrimal layer thickness and reduced viscous resistance. The time for the lens to return to the equilibrium shortens as the BC increase because of the resistance reduction. Conclusions: The movement of the contact lens is governed by the characteristics of the lacrimal layer between the lens and cornea as well as the lid blink.

  • PDF

Pulp and periodontal tissue changes following rapid tooth retraction by periodontal distraction in young adult dogs (유성견에서 periodontal distraction에 의한 급속 치아견인 시 치수 및 치주조직의 변화에 관한 연구)

  • Lee, Jong-Jin;Hong, Hyun-Sil;Chae, Jong-Moon;Jo, Jin-Hyung;Kim, Sang-Cheol
    • The korean journal of orthodontics
    • /
    • v.37 no.5
    • /
    • pp.351-363
    • /
    • 2007
  • The aim of this study was to evaluate pulp and periodontal changes following rapid tooth retraction by periodontal distraction after bone undermining surgery in young adult dogs. Methods: Alter extraction of second premolars, the interseptal bone mesial to the upper 3rd premolar was undermined. After activating the distraction appliance at 0.5 mm/day for six days, the dogs were sacrificed at 0, 1, 3, 5, 7, and 9 weeks during the consolidation period. Tissue changes of periodontium and pulp were evaluated radiologically, histologically, and immunohistochemically. Results: Digital subtraction radiography showed active bone formation in the stretched periodontal ligament from 0 - 4 weeks. Resorption of the alveolar bone, appearance of osteoclasts, and infiltration of inflammatory cells were observed just after the activation period at the pressure side, and distinctive bone formation was seen in the tension side of the periodontal ligament from 1 week. New bone formation was active at 1 - 3 weeks. The expression of calcitonin gene-related peptide in the experimental group was increased at the alveolar bone and pulp, and periodontal ligament at the pressure side from 0 - 1 week, and it decreased after 5 weeks to become similar to that of the control group. Conclusions: The results showed that rapid tooth movement using periodontal distraction can be new form of orthodontic tooth movement for accelerating normal bone formation.

Flow Regime Transition in Air-Molten Carbonate Salt Two-Phase Flow System (공기-탄산용융염 이상흐름계에서의 흐름영역전이)

  • Cho, Yung-Zun;Yang, Hee-Chul;Eun, Hee-Chul;Kang, Yong
    • Korean Chemical Engineering Research
    • /
    • v.47 no.4
    • /
    • pp.481-487
    • /
    • 2009
  • In this of study, effects of input air velocity(0.05~0.22 m/sec) and molten carbonate salt temperature ($870{\sim}970^{\circ}C$) on flow regime transition have been studied by adopting a drift-flux model of air holdup and a stochastic analysis of differential pressure fluctuations in an air-molten sodium carbonate salt two-phase system(molten salt oxidation process). Air holdup where the flow regime transition begins was determined by air holdup-drift flux plot. The air holdup value which the flow regime transition begins was increased with increasing molten carbonate salt temperature due to the decrease of viscosity and surface tension of molten carbonate salt. To characterize the flow regime transition more quantitatively, differential pressure fluctuation signals have been analyzed by adopting the stochastic method such as phase space portraits and Kolmogorov entropy, The Kolmogorov entropy decreased with an increasing of molten carbonate salt temperature but increased gradually with an increase in an air velocity, however, it exhibited different tendency with the flow regime and the air velocity value which flow regime transition begins was same to the results of drift-flux analysis.

A Review on Spray Characteristics of Bioethanol and Its Blended Fuels in CI Engines

  • No, Soo-Young
    • Journal of ILASS-Korea
    • /
    • v.19 no.4
    • /
    • pp.155-166
    • /
    • 2014
  • This review will be concentrated on the spray characteristics of bioethanol and its derived fuels such as ethanol-diesel, ethanol-biodiesel in compression ignition (CI) engines. The difficulty in meeting the severe limitations on NOx and PM emissions in CI engines has brought about many methods for the application of ethanol because ethanol diffusion flames in engine produce virtually no soot. The most popular method for the application of ethanol as a fuel in CI engines is the blending of ethanol with diesel. The physical properties of ethanol and its derivatives related to spray characteristics such as viscosity, density and surface tension are discussed. Viscosity and density of e-diesel and e-biodiesel generally are decreased with increase in ethanol content and temperature. More than 22% and 30% of ethanol addition would not satisfied the requirement of viscosity and density in EN 590, respectively. Investigation of neat ethanol sprays in CI engines was conducted by very few researchers. The effect of ambient temperature on liquid phase penetration is a controversial topic due to the opposite result between two studies. More researches are required for the spray characteristics of neat ethanol in CI engines. The ethanol blended fuels in CI engines can be classified into ethanol-diesel blend (e-diesel) and ethanol-biodiesel (e-biodiesel) blend. Even though dodecanol and n-butanol are rarely used, the addition of biodiesel as blend stabilizer is the prevailing method because it has the advantage of increasing the biofuel concentration in diesel fuel. Spray penetration and SMD of e-diesel and e-biodiesel decrease with increase in ethanol concentration, and in ambient pressure. However, spray angle is increased with increase in the ethanol percentage in e-diesel. As the ambient pressure increases, liquid phase penetration was decreased, but spray angle was increased in e-diesel. The increase in ambient temperature showed the slight effect on liquid phase penetration, but spray angle was decreased. A numerical study of micro-explosion concluded that the optimum composition of e-diesel binary mixture for micro-explosion was approximately E50D50, while that of e-biodiesel binary mixture was E30B70 due to the lower volatility of biodiesel. Adding less volatile biodiesel into the ternary mixture of ethanol-biodiesel-diesel can remarkably enhance micro-explosion. Addition of ethanol up to 20% in e-biodiesel showed no effect on spray penetration. However, increase of nozzle orifice diameter results in increase of spray penetration. The more study on liquid phase penetration and SMD in e-diesel and e-biodiesel is required.

Stability Analysis of Excavation Slope on Soft Ground (연약지반 굴착사면의 안정해석)

  • Kang, Yea Mook;Cho, Jae Hong;Kim, Yong Seong;Kim, Ji Hoon
    • Korean Journal of Agricultural Science
    • /
    • v.23 no.1
    • /
    • pp.25-38
    • /
    • 1996
  • To investigate the stability problem of irrigation-drainage channel excavation slope on soft ground, analyzed the behavior of the soft ground with excavation slope by the limit equilibrium method and the finite element method, and compared with field tests. The results of this study were summarized as follows; 1. When rapid drawdown the water level, the crack was occurred by the effect of the excess pore water pressure, and the pore water pressure was decreased slowly. 2. As the width of excavation was larger, the crack width was larger. And, excavated depth was deeper, the progressive failure was appeared. 3. When the soft ground excavation was small-scale, the minimum safety factor was more effected by cohesion(1.0, 1.5, 2.0, 2.5, 3.0) than excavated slope inclination(1:l, 1:1.5, 1:2). 4. As excavation was progressed, the settlement occurred on the top-slope due to plastic domain, and heaving was occurred at the bottom of excavation. 5. The maximum shear stress was appeared greatly as the base part of slope went down. Because of the increase of the maximum shear stress, tension area occurred and local failure possibility was increased. 6. As the excavation depth was increased, the maximum shear strain was appeared greatly at the base of slope and distribution pattern was concentrated beneath the middle of slope.

  • PDF

A simple approach to preserve keratinized mucosa around implants using a pre-fabricated implant-retained stent: a report of two cases

  • Park, Jung-Chul;Yang, Ki-Bin;Choi, You-Na;Kim, Yong-Tae;Jung, Ui-Won;Kim, Chang-Sung;Cho, Kyoo-Sung;Chai, Jung-Kiu;Kim, Chong-Kwan;Choi, Seong-Ho
    • Journal of Periodontal and Implant Science
    • /
    • v.40 no.4
    • /
    • pp.194-200
    • /
    • 2010
  • Purpose: There is no consensus regarding the relationship between the width of keratinized mucosa and the health of periimplant tissues, but clinicians prefer to provide enough keratinized mucosa around dental implants for long-term implant maintenance. An apically positioned flap during second stage implant surgery is the chosen method of widening the keratinized zone in simple procedures. However, the routine suture techniques used with this method tend to apply tension over the provisional abutments and decrease pre-existing keratinized mucosa. To overcome this shortcoming, a pre-fabricated implant-retained stent was designed to apply vertical pressure on the labial flap and stabilize it in a bucco-apical direction to create a wide keratinized mucous zone. Methods: During second stage implant surgery, an apically displaced, partial thickness flap with a lingualized incision was retracted. A pre-fabricated stent was clipped over the abutments after connecting to the provisional abutment. Vertical pressure was applied to displace the labial flap. No suture was required and the stent was removed after 10 days. Results: A clinically relevant amount of keratinized mucosa was achieved around the dental implants. Buccally displaced keratinized mucosa was firmly attached to the underlying periosteum. A slight shrinkage of the keratinized zone was noted after the healing period in one patient, but no discomfort during oral hygiene was reported. Clinically healthy gingiva with enough keratinized mucosa was achieved in both patients. Conclusions: The proposed technique is a simple and time-effective technique for preserving and providing keratinized tissue around dental implants.