• 제목/요약/키워드: Reactive Fluid

검색결과 120건 처리시간 0.032초

Experimental and Numerical Investigation for NOx Reduction with Fuel Lean Reburning System (NOx저감을 위한 연료희박 재연소 기법의 실험 및 수치적 연구)

  • Kim, Hak-Young;Baek, Seung-Wook;Son, Hee;Kim, Se-Won
    • Journal of the Korean Society of Combustion
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    • 제14권2호
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    • pp.18-25
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    • 2009
  • Fuel lean reburning method is very attractive way in comparison with conventional reburning method for reducing NOX. Meanwhile, the knowledge of the how flue gas re-circulated, temperature distribution and species concentration is crucial for the design and operation of an effective fuel lean reburning system. For this reason, numerical analysis of fuel lean reburning system is a very important and challenge task. In this work, the effect of fuel lean reburn system on NOX reduction has been experimentally and numerically conducted. Experimental study has been conducted with a 15kW lab scale furnace. Liquefied Petroleum Gas is used as main fuel and reburn fuel. To carry out numerical study, the finite-volume based commercial computational fluid dynamics (CFD) code FLUENT6.3 was used to simulate the reacting flow in a given laboratory furnace. Steady state, three dimensional analysis performed for turbulent reactive flow and radiative heat transfer in the furnace.

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Development of having double-chamber in micro-bubble pump (두 개의 챔버를 갖는 마이크로 버블펌프의 개발)

  • 최종필;박대섭;반준호;김병희;장인배;김헌영
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 한국정밀공학회 2003년도 춘계학술대회 논문집
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    • pp.1186-1190
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    • 2003
  • In this paper, a valveless bubble-actuated fluid micropump was has been developed and its performance was tested. The valveless micropump consists of the lower plate, the middle plate, the upper plate and a resistive heater. The lower plate includes the nozzle-diffuser elements and the double-chamber. Nozzle-diffuser elements and a double-chamber are fabricated on the silicon wafer by the DRIE(Deep Reactive Ion Etching) process. The lower plate also has inlet/outlet channels for fluid flow. The middle plate is made of glass and plays the role of the diaphragm. The chamber in the upper plate is filled with deionized water, and which contacts with the resistive heater. The resistive heater is patterned on a silicon substrate by Ti/Pt sputtering. Three plates and the resister heater are laminated by the aligner and bonded in the anodic bonder. Since the bubble is evaporated and condensed periodically in the chamber, the fluid flows from inlet to outlet with respect to the diffusion effect. In order to avoid backflow, the double chamber system is introduced. Analytical and experimental results show the validity of the developed double-chamber micropump.

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Effects of Building-roof Cooling on Scalar Dispersion in Urban Street Canyons (도시 협곡에서 건물 지붕 냉각이 스칼라 물질 확산에 미치는 영향)

  • Park, Soo-Jin;Kim, Jae-Jin
    • Atmosphere
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    • 제24권3호
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    • pp.331-341
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    • 2014
  • In this study, the effects of building-roof cooling on scalar dispersion in three-dimensional street canyons are investigated using a computational fluid dynamics (CFD) model. For this, surface temperature of building roof is systematically changed and non-reactive pollutants are released from street bottom in urban street canyons with the aspect ratio of 1. The characteristics of flow, air temperature, and non-reactive pollutant dispersion in the control experiment are analyzed first. Then, the effects of building-roof cooling are investigated by comparing the results with those in the control experiment. In the control experiment, a portal vortex which is a secondary flow induced by ambient air flow is formed in each street canyon. Averaged air temperature is higher inside the street canyon than in both sides of the street canyon, because warmer air is coming into the street canyon from the roof level. However, air temperature near the street bottom is lower inside the street canyon due to the inflow of cooler air from both sides of the street canyon. As building-roof temperature decreases, wind speed at the roof level increases and portal vortex becomes intensified (that is, downdraft, reverse flow, and updraft becomes stronger). Building-roof cooling contributes to the reduction of average concentration of the non-reactive pollutants and average air temperature in the street canyon. The results imply that building-roof cooling has positive effects on improvement of thermal environment and air quality in urban areas.

Seminal reactive oxygen species and total antioxidant capacity: Correlations with sperm parameters and impact on male infertility

  • Subramanian, Vidyalakshmi;Ravichandran, Aishwarya;Thiagarajan, Nivethitha;Govindarajan, Matheswari;Dhandayuthapani, Silambuchelvi;Suresh, Sujatha
    • Clinical and Experimental Reproductive Medicine
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    • 제45권2호
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    • pp.88-93
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    • 2018
  • Objective: The aim of this study was to measure reactive oxygen species (ROS) production and total antioxidant capacity (TAC) in the seminal fluid of the male partners in couples undergoing intrauterine insemination and to evaluate correlations between these values and their semen parameters. Methods: The study was conducted at Vamsam Fertility Center, Coimbatore, India and enrolled 110 male patients from whom semen samples were collected. ROS production was measured by a thiobarbituric acid reactive species assay, and TAC was measured by a 2,2-diphenyl-2-picrylhydrazyl free radical assay. The differences in the TAC and malondialdehyde (MDA) levels between the subfertile and fertile groups were analysed. Correlations between sperm parameters and TAC and MDA levels were statistically analysed, and cutoff values with respect to the controls were determined. All hypothesis tests used were two-tailed, with statistical significance assessed at the level of p< 0.05. Results: A total of 87 subfertile and 23 fertile men were included in the study. The mean MDA level was significantly higher in the subfertile subjects than in the fertile subjects, and the mean antioxidant level was significantly lower in the subfertile subjects than in the fertile subjects. Seminal MDA levels were negatively associated with sperm concentration, motility, and morphology, whereas the opposite was seen with TAC levels. Conclusion: Measurements of seminal TAC and ROS are valuable for predicting semen quality, and hence predicting the outcomes of fertility treatment.

Relationship between Obesity, Gingival Inflammation, and Periodontal Bacteria after 4-Week Weight Control Program in 20's

  • Seo, Min-Seock;Hwang, Soo-Jeong
    • Journal of dental hygiene science
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    • 제22권2호
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    • pp.99-107
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    • 2022
  • Background: Obesity weakens acquired immunity and causes infection. This study aimed to investigate the relationship between the inflammatory markers in the gingival crevicular fluid and serum and periodontal bacteria in saliva through obesity control for 4 weeks. Methods: Forty-six subjects with a body mass index (BMI) of ≥23 kg/m2 stayed in the camp for 4 weeks, followed by exercise and a low salt-low fat diet. Body size measurements, oral examinations, blood, saliva, and gingival crevicular fluid were collected before and after the program. C-reactive protein (CRP) in serum, matrix metalloproteinase (MMP)-8, MMP-9, and interleukin (IL)-1β in the gingival sulcus fluid were measured. After extracting bacterial genomic DNA from saliva, the presence of periodontal bacteria were detected using Taq probe. The relationship of each index before and after the program was analyzed through paired t-test and partial correlation analysis. Results: Campylobacter rectus (Cr) increased after the program, and there was no significant change in other bacteria. Serum CRP and Fusobacterium nucleatum (Fn), Aggregatibacter actinomycetemcomitans, Cr, ratio of Fn, and ratio of Cr had a positive relationship at baseline; however, the relationship was not significant after the program. Ratio of Prevotella intermedia had a positive relationship with MMP-9, MMP-8, IL-1β at baseline. Moreover, the ratio of Treponema denticola and the ratio of Tannerella forsythia showed a positive relationship with MMP-8, MMP-9, and IL-1β. The relationship between the ratio of Porphyromonas gingivalis and IL-1β showed a constant positive relationship at baseline and after the program. Conclusion: Obesity control program in subjects with a BMI of ≥23 kg/m2 accompanied by diet and exercise did not affect the changes in periodontal bacteria itself, but changes in the relationship between periodontal bacteria and serum CRP, the relationship between the inflammatory index in the gingival crevicular fluid and periodontal bacteria was observed.

Effects of NaOCl on the Intracellular Calcium Concentration in Rat Dorsal Root Ganglion Neurons

  • Lee, Hae-In;Chun, Sang-Woo
    • International Journal of Oral Biology
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    • 제35권3호
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    • pp.129-135
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    • 2010
  • Recent studies have implicated reactive oxygen species (ROS) as determinants of the pathological pain caused by the activation of peripheral neurons. It has not been elucidated, however, how ROS activate the primary sensory neurons in the pain pathway. In this study, calcium imaging was performed to investigate the effects of NaOCl, a ROS donor, on the intracellular calcium concentration ($[Ca^{2+}]i$) in acutely dissociated dorsal root ganglion (DRG) neurons. DRG was sequentially treated with 0.2 mg/ml of both protease and thermolysin, and single neurons were then obtained by mechanical dissociation. The administration of NaOCl then caused a reversible increase in the $[Ca^{2+}]i$, which was inhibited by pretreatment with phenyl-N-tertbuthylnitrone (PBN) and isoascorbate, both ROS scavengers. The NaOCl-induced $[Ca^{2+}]i$ increase was suppressed both in a calcium free solution and after depletion of the intracellular $Ca^{2+}$ pool by thapsigargin. Additionally, this increase was predominantly blocked by pretreatment with the transient receptor potential (TRP) antagonists, ruthenium red ($50\;{\mu}M$) and capsazepine ($10\;{\mu}M$). Collectively, these results suggest that an increase in the intracellular calcium concentration is produced from both extracellular fluid and the intracellular calcium store, and that TRP might be involved in the sensation of pain induced by ROS.

A Study of Transonic Premixed Combustion in a Diverging Channel Using Asymptotic Analysis (점근해석을 이용한 확대형 채널 내의 천음속 예혼합 연소에 관한 연구)

  • Lee, Jang-Chang
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • 제33권8호
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    • pp.75-83
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    • 2005
  • A steady transonic dilute premixed combustion in a diverging channel is investigated by using asymptotic analysis. This model explores the nonlinear interactions between the near-sonic speed of the flow, the small changes in geometry from a straight channel, and the small heat release due to the one-step first-order Arrhenius chemical reaction. The reactive flow is described by a nonhomogeneous transonic small-disturbance (TSD) equation coupled with an ordinary differential equation for the calculation of the reactant mass fraction in the combustible gas. Also the asymptotic analysis reveals the similarity parameters that govern the reacting flow problem. The results show the complicated nonlinear interaction between the convection, reaction, and geometry effects and its effect on the flow behavior.

Glycine induces enhancement of bactericidal activity of neutrophils

  • Kang, Shin-Hae;Ham, Hwa-Yong;Hong, Chang-Won;Song, Dong-Keun
    • The Korean Journal of Physiology and Pharmacology
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    • 제26권4호
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    • pp.229-238
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    • 2022
  • Severe bacterial infections are frequently accompanied by depressed neutrophil functions. Thus, agents that increase the microbicidal activity of neutrophils could add to a direct antimicrobial therapy. Lysophosphatidylcholine augments neutrophil bactericidal activity via the glycine (Gly)/glycine receptor (GlyR) α2/TRPM2/p38 mitogen-activated protein kinase (MAPK) pathway. However, the direct effect of glycine on neutrophil bactericidal activity was not reported. In this study, the effect of glycine on neutrophil bactericidal activity was examined. Glycine augmented bactericidal activity of human neutrophils (EC50 = 238 μM) in a strychnine (a GlyR antagonist)-sensitive manner. Glycine augmented bacterial clearance in mice, which was also blocked by strychnine (0.4 mg/kg, s.c.). Glycine enhanced NADPH oxidase-mediated reactive oxygen species (ROS) production and TRPM2-mediated [Ca2+]i increase in neutrophils that had taken up E. coli. Glycine augmented Lucifer yellow uptake (fluid-phase pinocytosis) and azurophil granule-phagosome fusion in neutrophils that had taken up E. coli in an SB203580 (a p38 MAPK inhibitor)-sensitive manner. These findings indicate that glycine augments neutrophil microbicidal activity by enhancing azurophil granule-phagosome fusion via the GlyRα2/ROS/calcium/p38 MAPK pathway. We suggest that glycine could be a useful agent for increasing neutrophil bacterial clearance.

The antioxidative and cytoprotective effect of Lonicerae japonicae Flos water extracts on the ultraviolet(UV)B-induced human HaCaT keratinocytes (금은화 물추출물의 항산화 효과와 Ultraviolet(UV)B로 유도된 사람 각질형성세포 손상에 대한 보호효과)

  • Seo, Seung-Hee;Bae, Gi-Sang;Choi, Sun Bok;Jo, Il-Joo;Kim, Dong-Goo;Shin, Joon-Yeon;Song, Ho-Joon;Park, Sung-Joo;Choi, Mee-Ok
    • The Korea Journal of Herbology
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    • 제29권6호
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    • pp.63-71
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    • 2014
  • Objectives : Lonicerae japonicae Flos(LJF) has been reported to exhibit anti-oxidant, anti-inflammatory, anti-viral, anti-rheumatoid properties. However, it is still largely unknown whether LJF inhibits the ultraviolet(UV)B-induced oxidative damage in human HaCaT keratinocytes. Therefore in this paper, we investigated the anti-oxidative capacity and protective effect of LJF against UVB-induced oxidative demage in human HaCaT keratinocytes. Methods : To evaluate the anti-oxidative activity of LJF extracts, we measured total phenolic contents, total flavonoid contents, antioxidant capacity, and superoxide scavenging activity. To give an oxidative stress to HaCaT cells, UVB was irradiated with $200mJ/cm^2$ to HaCaT cells. To detect the protective effect of LJF against UVB, we measured cell viability, DNA fragmentation and reactive oxygen species (ROS) production. In addition, we performed high-performance liquid chromatography (HPLC) analysis to find a major component of LJF. Results : LJF contained phenolic and flavonoid contents, and showed the anti-oxidant and superoxide scavenging activity. The UVB-induced oxidative conditions led to the cell death, DNA fragmentation and reactive oxygen species (ROS) production. However, pretreatment with LJF reduced oxidative conditions, including inhibition of cell death, DNA fragmentation and ROS production. In addition, we found out chlorogenic acid as major component of LJF. Conclusions : These results could suggest that LJF contained anti-oxidative contents and exhibited protective effects against UVB on human HaCaT keratinocytes. And the effective compound of LJF which could show protective activities against UVB is chlorogenic acid. Thus, LJF and chlorogenic acid would be useful for the development of drug or cosmetics treating skin troubles.

Impact of scaling and root planing on C-reactive protein levels in gingival crevicular fluid and serum in chronic periodontitis patients with or without diabetes mellitus

  • Mohan, Mahendra;Jhingran, Rajesh;Bains, Vivek Kumar;Gupta, Vivek;Madan, Rohit;Rizvi, Iram;Mani, Kanchan
    • Journal of Periodontal and Implant Science
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    • 제44권4호
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    • pp.158-168
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    • 2014
  • Purpose: The present study was conducted to evaluate the impact of scaling and root planing (SRP) on the C-reactive protein (CRP) levels of gingival crevicular fluid (GCF) and serum in chronic periodontitis patients with type 2 diabetes mellitus (T2DM-CP) or without type 2 diabetes mellitus (NDM-CP). Methods: Forty-eight human participants were divided into two groups: an experimental (T2DM-CP) group (group I, n=24) comprising chronic periodontitis patients with random blood sugar ${\geq}200mg/dL$ and type 2 diabetes mellitus, and control (NDM-CP) group (group II, n=24) of those with chronic periodontitis and random blood sugar <200 without T2DM for the study. All subjects underwent nonsurgical periodontal therapy (NSPT) including complete SRP and subgingival debridement. Periodontal health parameters, plaque index (PI), gingival index (GI), probing pocket depth (PPD), clinical attachment level (CAL), GCF volume (GCF vol), GCF-CRP, random blood glucose (RBS), glycated hemoglobin, and systemic inflammatory markers, serum CRP, total leukocyte count (TLC), neutrophil count (Neutr) and lymphocyte count (Lymph), were evaluated at baseline, 1 month, and 3 months after SRP. Results: NSPT resulted in statistically significant improvement in periodontal health parameters (PI, GI, PPD, CAL, GCF vol), CRP levels in serum as well as GCF of both groups I and II. The mean improvement in periodontal health parameters (PI, GI, PPD, CAL, GCF vol), CRP levels in serum and GCF was greater in group I than group II after NSPT. There was nonsignificant increase in GCF-CRP, TLC, Lymph, and RBS, and a significant increase in Neutr and Serum CRP in group II at 1 month. The Serum CRP level of 20 out of 24 group II patients had also increased at 1 month. Conclusions: The CRP levels in both GCF and serum were higher in T2DM-CP patients than in NDM-CP patients. Although there was a significant improvement in both the groups, greater improvement was observed in both GCF and serum samples of T2DM-CP patients.