• Title/Summary/Keyword: surface acting

Search Result 563, Processing Time 0.024 seconds

Phellopterin Suppresses Airway Mucin Secretion induced by Adenosine Triphosphate

  • Heo, Ho-Jin;Kim, Cheol-Su;Lee, Hyun-Jae;Kim, Jin-Woong;Kim, Young-Sik;Kang, Sam-Sik;Seo, Un-Kyo;Kim, Yun-Hee;Park, Yang-Chun;Seok, JeongHo;Lee, Choong-Jae
    • Biomolecules & Therapeutics
    • /
    • v.14 no.4
    • /
    • pp.202-206
    • /
    • 2006
  • Angelicae Dahiricae Radix has been used for controlling inflammatory respiratory diseases in oriental medicine and their components, phellopterin, isoimperatorin and byakangelicol were reported to have various biological effects. In this study, we investigated whether phellopterin, isoimperatorin and byakangelicol affect adenosine triphosphate(ATP)-induced mucin secretion from cultured airway epithelial cells. Confluent primary hamster tracheal surface epithelial(HTSE) cells were metabolically radiolabeled using $^3H$-glucosamine for 24 h and chased for 30 min in the presence of varying concentrations of each agent to assess the effects on $^3H$-mucin secretion. The results were as follows: 1) phellopterin significantly inhibited ATP-induced mucin secretion; 2) However, isoimperatorin and byakangelicol did not affect ATP-induced mucin secretion, significantly. This result suggests that phellopterin can regulate 'mucin secretion induced by ATP'-a phenomenon simulating mucus overproduction from inflamed airway epithelial cells-by directly acting on airway mucin-secreting cells. Therefore, phellopterin should further be investigated for the possible use as mucoregulators in the treatment of inflammatory airway diseases.

Effect of Imperatorin on Adenosine Triphosphate-stimulated Mucin Secretion from Airway Epithelial Cells

  • Heo, Ho-Jin;Kim, Cheol-Su;Lee, Hyun-Jae;Shin, Seung-Won;Kim, Young-Sik;Kang, Sam-Sik;Park, Yang-Chun;Kim, Yun-Hee;Seo, Un-Kyo;Seok, Jeong-Ho;Lee, Choong-Jae
    • Biomolecules & Therapeutics
    • /
    • v.14 no.4
    • /
    • pp.235-239
    • /
    • 2006
  • Angelicae Koreanae Radix has been used for controlling inflammatory respiratory diseases in folk medicine and their components, imperatorin, marmesinin and oxypeucedanin were reported to have diverse biological effects. In this study, we investigated whether imperatorin, marmesinin and oxypeucedanin affect adenosine triphosphate(ATP)-induced mucin secretion from cultured airway epithelial cells. Confluent primary hamster tracheal surface epithelial(HTSE) cells were metabolically radiolabeled using $^3H$-glucosamine for 24 h and chased for 30 min in the presence of varying concentrations of each agent to assess the effects on $^3H$-mucin secretion. The results were as follows: 1) imperatorin significantly inhibited ATP-induced mucin secretion; 2) However, marmesinin and oxypeucedanin did not affect ATP-induced mucin secretion, significantly. We conclude that imperatorin might inhibit ATP-induced mucin secretion by directly acting on airway mucin-secreting cells. Therefore, imperatorin should further be investigated for the possible use as mucoregulators in the treatment of inflammatory airway diseases.

Flow-induced pressure fluctuations of a moderate Reynolds number jet interacting with a tangential flat plate

  • Marco, Alessandro Di;Mancinelli, Matteo;Camussi, Roberto
    • Advances in aircraft and spacecraft science
    • /
    • v.3 no.3
    • /
    • pp.243-257
    • /
    • 2016
  • The increase of air traffic volume has brought an increasing amount of issues related to carbon and NOx emissions and noise pollution. Aircraft manufacturers are concentrating their efforts to develop technologies to increase aircraft efficiency and consequently to reduce pollutant discharge and noise emission. Ultra High By-Pass Ratio engine concepts provide reduction of fuel consumption and noise emission thanks to a decrease of the jet velocity exhausting from the engine nozzles. In order to keep same thrust, mass flow and therefore section of fan/nacelle diameter should be increased to compensate velocity reduction. Such feature will lead to close-coupled architectures for engine installation under the wing. A strong jet-wing interaction resulting in a change of turbulent mixing in the aeroacoustic field as well as noise enhancement due to reflection phenomena are therefore expected. On the other hand, pressure fluctuations on the wing as well as on the fuselage represent the forcing loads, which stress panels causing vibrations. Some of these vibrations are re-emitted in the aeroacoustic field as vibration noise, some of them are transmitted in the cockpit as interior noise. In the present work, the interaction between a jet and wing or fuselage is reproduced by a flat surface tangential to an incompressible jet at different radial distances from the nozzle axis. The change in the aerodynamic field due to the presence of the rigid plate was studied by hot wire anemometric measurements, which provided a characterization of mean and fluctuating velocity fields in the jet plume. Pressure fluctuations acting on the flat plate were studied by cavity-mounted microphones which provided point-wise measurements in stream-wise and spanwise directions. Statistical description of velocity and wall pressure fields are determined in terms of Fourier-domain quantities. Scaling laws for pressure auto-spectra and coherence functions are also presented.

Effect of Al Addition on the Cryogenic-Temperature Impact Properties of Austenitic Fe-23Mn-0.4C Steels (알루미늄 첨가에 따른 오스테나이트계 Fe-23Mn-0.4C 고망간강의 극저온 충격 특성)

  • Kim, Sang-Gyu;Kim, Jae-Yoon;Yun, Tae-Hee;Hwang, Byoungchul
    • Korean Journal of Materials Research
    • /
    • v.31 no.9
    • /
    • pp.519-524
    • /
    • 2021
  • The impact properties of two austenitic Fe-23Mn-0.4C steels with different Al contents for cryogenic applications are investigated in this study. The 4Al steel consists mostly of austenite single-phase microstructure, while the 5Al steel exhibits a two-phase microstructure of austenite and delta-ferrite with coarse and elongated grains. Charpy impact test results reveal that the 5Al steel with duplex phases of austenite and delta-ferrite exhibits a ductile-to-brittle transition behavior, while the 4Al steel with only single-phase austenite has higher absorbed energy over 100 J at -196 ℃. The SEM fractographs of Charpy impact specimens show that the 4Al steel has a ductile dimple fracture regardless of test temperature, whereas the 5Al steel fractured at -100 ℃ and -196 ℃ exhibits a mixed fracture mode of both ductile and brittle fractures. Additionally, quasi-cleavage fracture caused by crack propagation of delta-ferrite phase is found in some regions of the brittle fracture surface of the 5Al steel. Based on these results, the delta-ferrite phase hardly has a significant effect on absorbed energy at room-temperature, but it significantly deteriorates low-temperature toughness by acting as the main site of the propagation of brittle cracks at cryogenic-temperatures.

Experimental Study on Ventilation and Shaft Excitation Force of a Propeller in Partially Submerged Condition (부분 침수 조건에서 작동하는 프로펠러의 공기유입과 축계 기진력에 대한 실험적 연구)

  • Ha, Jeongsoo;Seo, Jeonghwa;Park, Gyukpo;Park, Jongyeol;Rhee, Shin Hyung;Yoo, Jaehoon;Park, Suyeong
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.58 no.1
    • /
    • pp.40-48
    • /
    • 2021
  • Through a series of bollard pull tests of a propeller in partially submerged condition, thrust, torque, and shaft excitation force of a conventional propeller model were measured using a six-component load cell. By variation of the Weber number and Reynolds number, a consistent towing tank model test condition was derived. The effects of propeller immersion depth on the ventilation behavior and change of force and moment acting onto the propeller shaft were investigated. The decrease in thrust owing to the inception of ventilation was confirmed, and a large degree of dispersion of the thrust and torque coefficients were also observed in the transition region where the blade tip was under the water surface. The shaft excitation force was derived from the force and moment onto the propeller shaft.

Effects of Self-Efficacy and Job Stress on Organizational Commitment among Clinical Dental Hygienists

  • Lee, Kyeong-Jin;Kim, Young-im
    • Journal of dental hygiene science
    • /
    • v.19 no.1
    • /
    • pp.60-66
    • /
    • 2019
  • Background: This study aimed to provide basic data to establish a foundation for efficient operation of the organization by assessing the effects of self-efficacy and job stress (measured by self-efficacy, job demand, and job autonomy) on organizational commitment among clinical dental hygienists. Methods: This was a cross-sectional survey study that used a self-administered questionnaire to collect data. After institutional review board approval, a survey was conducted from January to May 2017, targeting dental hygienists working in dental clinics and hospitals. The final 199 questionnaires were analyzed with PASW 18.0 for Windows (IBM Corp.). The data were analyzed using mean and/or standard deviation t-test, one-way ANOVA, and multiple regression analysis. Results: The means for self-efficacy, job demand, job autonomy, and organizational commitment were $55.94{\pm}9.65$, $26.55{\pm}2.29$, $20.24{\pm}3.88$, and $49.49{\pm}8.39$, respectively. Along with self-efficacy, the other factors of organizational commitment among dental hygienists that were statistically significant included job autonomy, mean salary (2,500~2,990 thousand Korean won [KRW] and ${\geq}3,000$ thousand KRW), and employee welfare (good), which are sub-areas of the surface acting. In other words, it was found that the higher the mean salary, the better the employee welfare, the higher self-efficacy, and the higher the organizational commitment, and the explanatory power of the model was approximately 42.1%. Conclusion: These results suggest that the higher the self-efficacy, job autonomy, mean salary, and employee welfare, the higher the organizational commitment. In order to improve job demand among dental hygienists, it is necessary to establish an effective plan to improve job welfare, self-efficacy, and job autonomy.

Development of Carbon Felt Electrode Using Urea for Vanadium Redox Flow Batteries (Urea를 이용한 바나듐 레독스 흐름 전지용 카본 펠트 전극 개발)

  • Kim, So Yeon;Kim, Hansung
    • Korean Chemical Engineering Research
    • /
    • v.57 no.3
    • /
    • pp.408-412
    • /
    • 2019
  • In this study, nitrogen doped carbon felt was prepared by pyrolysis of urea at high temperature and applied as an electrode for vanadium redox flow cell. Urea is easier to handle than ammonia and forms $NH_2$ radicals at higher temperatures, creating a nitrogen functional group on the carbon surface and acting as an active site in the vanadium redox reaction. Therefore, the discharge capacity of activated carbon felt electrodes using urea was 14.9 Ah/L at a current density of $150mA/cm^2$, which is 23% and 187% higher than OGF and GF, respectively. These results show the possibility that activated carbon felt electrode using urea can be used as electrode material for redox flow battery.

Computational Model for Hydrodynamic Pressure on Radial Gates during Earthquakes (레디얼 게이트에 작용하는 지진 동수압 계산 모형)

  • Phan, Hoang Nam;Lee, Jeeho
    • Journal of the Computational Structural Engineering Institute of Korea
    • /
    • v.32 no.5
    • /
    • pp.323-331
    • /
    • 2019
  • In this study, a computational model approach for the modeling of hydrodynamic pressures acting on radial gates during strong earthquakes is proposed. The use of the dynamic layering method with the Arbitrary Lagrangian Eulerian (ALE) algorithm and the SIMPLE method for simulating free reservoir surface flow in addition to moving boundary interfaces between the fluid domain and a structure due to earthquake excitation are suggested. The verification and validation of the proposed approach are realized by comparisons performed using the renowned formulation derived by the experimental results for vertical and inclined dam surfaces subjected to earthquake excitation. A parameter study for the truncated lengths of the two-dimensional fluid domain demonstrates that twice the water level leads to efficient and converged computational results. Finally, numerical simulations for large radial gates with different curvatures subjected to two strong earthquakes are successfully performed using the suggested computational model.

Effect of T6 and T73 Heat Treatments on Microstructure, Mechanical Responses and High Cycle Fatigue Properties of AA7075 Alloy Modified with Mg and Al2Ca ((Mg + Al2Ca)로 개량된 AA7075 합금의 미세조직, 기계적 특성, 그리고 고주기 피로 특성에 미치는 T6 및 T73 열처리의 효과)

  • Hwang, Y.J.;Kim, G.Y.;Kim, K.S.;Kim, Shae K.;Yoon, Y.O.;Lee, K.A.
    • Transactions of Materials Processing
    • /
    • v.30 no.1
    • /
    • pp.5-15
    • /
    • 2021
  • The effects of heat treatments (T6 and T73) on the microstructure, mechanical properties, and high cycle fatigue behavior of modified AA7075 alloys were investigated. A modified 7075 alloy was manufactured using modified-Mg (Mg-Al2Ca) instead of the conventional element Mg. Based on the microstructure, the average grain size was 4.5 ㎛ (T6) and 5.2 ㎛ (T73). Regardless of heat treatment, the modified AA7075 alloys consisted of Al matrix containing homogeneously distributed Al2CuMg and MgZn2 phases with reduced Fe-intermetallic compound. Room temperature tensile tests showed that the properties of modified 7075-T6 (Y.S.: 622MPa, T.S: 675MPa, elongation: 15.4%) were superior to those of T73 alloy (Y.S.: 492MPa, T.S: 548MPa, elongation: 12.8%). Experimental data show that the fatigue life of T6 was 400 MPa, about 64% of its yield strength. However, the fatigue life of T73 alloy was 330 MPa and 67%. Irrespective of the stress level, all crack initiation points were located on the specimen surface, and no inclusions acting as stress concentrators were seen. Superior mechanical properties and high cycle fatigue behavior of modified AA7075-T6 alloy are attributed to the fine grains and homogeneous distribution of small second phases such as MgZn2 and Al2CuMg, in addition to reduced Fe-intermetallic compounds.

Continuous Excavation Type TBM Parts Modification and Control Technology for Improving TBM Performance (TBM 굴진향상을 위한 연속굴착형 TBM 부품개조 및 제어기술 소개)

  • Young-Tae, Choi;Dong-Geon, Lee;Mun-Gyu, Kim;Joo-Young, Oh;Jung-Woo, Cho
    • Tunnel and Underground Space
    • /
    • v.32 no.6
    • /
    • pp.345-352
    • /
    • 2022
  • The existing NATM (New Austrian Tunneling Method) has induced civil compliants due to blasting vibration and noise. Machanized excavation methods such as TBM (Tunnel Boring Machine) are being adopted in the planning and construction of tunneling projects. Shield TBM method is composed of repetition processes of TBM excavation and segment installation, the machine has to be stopped during the later process. Consecutive excavation technology using helical segment is under developing to minimize the stoppage time. The modification of thrust jacks and module are planned to ensure the advance force acting on the inclined surface of helical segment. Also, the integrated system design of hydraulic circuit will be remodeled. This means that the system deactivate the jacks on the installing segment while the others automatically act the thrusting forces on the existing segments. This report briefly introduces the mechanical research part of the current consecutive excavation technological development project of TBM.