Propagation of an Air Finger Into a Fluid Filled Bifurcation

2010 ◽  
Author(s):  
Benjamin L. Vaughan ◽  
James B. Grotberg
Keyword(s):  
Numerical Model ◽  
Viscous Fluid ◽  
Pressure Difference ◽  
Respiratory Diseases ◽  
Critical Pressure ◽  
Distress Syndrome ◽  
The Other ◽  
Liquid Plug ◽  
Pulmonary Airways ◽  
Single Branch

The occlusion of pulmonary airways can be caused by many respiratory diseases such as respiratory distress syndrome. It is believed that these occluded airways are reopened by the propagation of an air finger. The mechanics of airway reopening have been studied in-depth for an individual airway [1,2] without considering the frequent branching of pulmonary airways. The presence of a bifurcation leads to the question of whether the propagating air finger will clear both branches of the airway or will propagate through a single branch, leaving the other branch occluded. The propagation of a finite length liquid plug through a fixed bifurcation has been studied experimentally [3, 4]. We wish to develop a numerical model for the propagation of an air finger through bifurcating channel filled with a viscous fluid. In this model, the air finger is driven by a pressure difference between the parent channel and the two daughter branches. The presence of an additional pressure difference between the two branches can cause unsymmetrical splitting of the air finger and, above a critical pressure difference, prevent the clearance of both branches.

The effectiveness of waist-shaped and straight-shaped interdental brushes in cleaning implant overdenture attachments: a self-controlled clinical trial

2020 ◽  
Author(s):  
Qiuwen Chen ◽  
Yanjun Ge ◽  
Jinyou Chai ◽  
Hailan Feng ◽  
Jianzhang Liu ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Oral Hygiene ◽  
Respiratory Diseases ◽  
The Other ◽  
Controlled Clinical Trial ◽  
Cleaning Procedure ◽  
Plaque Removal ◽  
Line Angle ◽  
Implant Overdenture ◽  
Interdental Brush

Elderly patients often find it challenging to remove plaque accumulated on the attachments of implant overdentures (IOD) using conventional cleaning instruments. Further, excessive plaque accumulation can lead to peri-implant diseases and occasionally to respiratory diseases. Therefore, here, we aimed to compare the effectiveness of waist-shaped interdental brushes (WIB) with that of straight-shaped ones (SIB) in plaque removal from the locator attachments of IOD. Twenty participants with two locator attachments retaining mandibular IOD participated in this study. After the baseline cleaning, the participants refrained from oral hygiene maintenance for 3 days. A dentist cleaned one of the attachments using the WIB and the other attachment using the SIB. The pre- and post-cleaning modified plaque index (mPLI) scores were recorded. Following another 3 days free from oral hygiene maintenance, the trained participants repeated the same cleaning procedure using the WIB and SIB. Pre- and post-cleaning mPLI scores were recorded. Regardless of the type of brush used, the post-cleaning mPLI scores were lower than the pre-cleaning ones. After the cleaning procedure, the overall mean mPLI score was lower in the WIB group than in the SIB group. The post-cleaning mPLI scores at the line-angles and on the axial surfaces of the attachments were also lower in the WIB group than in the SIB group. There was no difference in the cleaning effectiveness between the dentist and participants when they used the same type of interdental brush. The WIB was significantly more efficient in plaque removal than the SIB, especially at the line-angle sites.

scholarly journals Administration route governs the therapeutic efficacy, biodistribution and macrophage targeting of anti-inflammatory nanoparticles in the lung

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Lu Wang ◽  
Yafei Rao ◽  
Xiali Liu ◽  
Liya Sun ◽  
Jiameng Gong ◽  
...  
Keyword(s):  
Therapeutic Efficacy ◽  
Lung Inflammation ◽  
Respiratory Diseases ◽  
Inflammatory Responses ◽  
The Other ◽  
Target Cells ◽  
Administration Route ◽  
Toll Like Receptor ◽  
Administration Routes ◽  
Anti Inflammatory

Abstract Background Uncontrolled inflammation is a central problem for many respiratory diseases. The development of potent, targeted anti-inflammatory therapies to reduce lung inflammation and re-establish the homeostasis in the respiratory tract is still a challenge. Previously, we developed a unique anti-inflammatory nanodrug, P12 (made of hexapeptides and gold nanoparticles), which can attenuate Toll-like receptor-mediated inflammatory responses in macrophages. However, the effect of the administration route on its therapeutic efficacy and tissue distribution remained to be defined. Results In this study, we systematically compared the effects of three different administration routes [the intratracheal (i.t.), intravenous (i.v.) and intraperitoneal (i.p.)] on the therapeutic activity, biodistribution and pulmonary cell targeting features of P12. Using the LPS-induced ALI mouse model, we found that the local administration route via i.t. instillation was superior in reducing lung inflammation than the other two routes even treated with a lower concentration of P12. Further studies on nanoparticle biodistribution showed that the i.t. administration led to more accumulation of P12 in the lungs but less in the liver and other organs; however, the i.v. and i.p. administration resulted in more nanoparticle accumulation in the liver and lymph nodes, respectively, but less in the lungs. Such a lung favorable distribution was also determined by the unique surface chemistry of P12. Furthermore, the inflammatory condition in the lung could decrease the accumulation of nanoparticles in the lung and liver, while increasing their distribution in the spleen and heart. Interestingly, the i.t. administration route helped the nanoparticles specifically target the lung macrophages, whereas the other two administration routes did not. Conclusion The i.t. administration is better for treating ALI using nanodevices as it enhances the bioavailability and efficacy of the nanodrugs in the target cells of the lung and reduces the potential systematic side effects.

Practical Aspects of Propulsion Shaft Alignment

2021 ◽  
Author(s):  
Kyriakos Avgouleas ◽  
Emmanouil Sarris ◽  
George Gougoulidis
Keyword(s):  
Cost Effectiveness ◽  
Numerical Model ◽  
High Speed ◽  
The Other ◽  
Technical Literature ◽  
Trade Off ◽  
Fea Model ◽  
Shaft Alignment ◽  
Alignment Strategy ◽  
Potential Damage

The economical and operational implications of poor alignment are indisputable for the propulsion shafting system of a commercial vessel. This holds true for naval vessels as well, although far less documented in the technical literature. This paper addresses some of the challenges associated with the proper alignment of a high-speed naval craft, which has been in service for many years. Laser bore-sighting was performed on a Guided Missile Fast Patrol Boat resting on a docking cradle. The measured bearing offsets were input to a FEA model of the shafting system to calculate bearing reactions and detect potential misalignment issues. Subsequent decisions regarding corrective measures take into account the results computed by the numerical model, experience from sister ships, the available documentation from the building yard and several other factors which are discussed in the paper. The solutions proposed are targeted towards a balanced trade-off between cost effectiveness and out-of-service time on one hand, and the risk of potential damage from misalignment on the other hand, which would seriously disrupt the ship’s operational availability. Practical aspects and lessons identified in the process are also presented, which demonstrate the distinct differences in alignment strategy of a high-speed naval craft compared to a typical commercial vessel.

Fractality of Simulated Fracture

2009 ◽  
Vol 409 ◽  
pp. 154-160 ◽  
Author(s):  
Petr Frantík ◽  
Zbyněk Keršner ◽  
Václav Veselý ◽  
Ladislav Řoutil
Keyword(s):  
Numerical Model ◽  
Elastic Plate ◽  
Model Simulation ◽  
Element Model ◽  
The Other ◽  
Particle Model ◽  
Discrete Element Model ◽  
Fractal Nature ◽  
Discrete Elements ◽  
The Impact

The paper is focussed on numerical simulations of the fracture of a quasi-brittle specimen due to its impact onto a fixed rigid elastic plate. The failure of the specimen after the impact is modelled in two ways based on the physical discretization of continuum: via physical discrete elements and pseudo-particles. Advantages and drawbacks of both used methods are discussed. The size distribution of the fragments of the broken specimen resulting from physical discrete element model simulation follows a power law, which indicates the ability of the numerical model to identify the fractal nature of the fracture. The pseudo-particle model, on the other side, can successfully predict the kinematics of the fragments of the specimen under impact failure.

Numerical Simulation Research on the Shape of Top Coal Drawn-Body in Gently Inclined Seam

2012 ◽  
Vol 468-471 ◽  
pp. 2248-2254
Author(s):  
Qiang Li ◽  
Wan Kui Bu ◽  
Hui Xu ◽  
Xiao Bo Song
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Random Medium ◽  
Body Movement ◽  
The Other ◽  
Simulation Research ◽  
Research Results ◽  
Shape Equation ◽  
The Difference ◽  
Meso Scale

The numerical model of top coal drawing in gently inclined seam is built based on PFC2d software. By comparing with the theory of drawn-body movement law, it can be obtained that the shape of top coal drawn-body accords with the theory of random medium movement. The research results show that the form of the shape equation of top coal drawn-body is uniform while the top coal caving angle is different. On the other hand, with the difference of top coal caving angle and drawing height, the shape of top coal drawn-body is differential at the meso scale, which depends on the parameters of the shape equation of top coal drawn-body.

scholarly journals Modelling the impact of microbial contamination of fuel filtration efficiency

2017 ◽  
Vol 169 (2) ◽  
pp. 133-136
Author(s):  
Rafał KRAKOWSKI
Keyword(s):  
Numerical Model ◽  
Microbial Contamination ◽  
Petroleum Products ◽  
Filtration Efficiency ◽  
The Other ◽  
Entire System ◽  
Factors Influencing ◽  
Three Stages ◽  
The Impact ◽  
Growth Of Bacteria

In this paper the concept of filtration and the problem of microbial contamination occurring in the fuels and oils was presented. Then the factors influencing the growth of bacteria in petroleum products were described in detail. In the next part of the article modeling of the impact of fuel microbial contamination on filtration efficiency was performed. The modeling presented in the article is an example showing how undesirable phenomenon is the microbial contamination and how pollution affects the other elements of the entire system. As part of the modeling, numerical model of filtration with the solution was presented. Then analysis results on the basis of the impurities concentration characteristics in the fuel as a function of the fouling thickness in the partition of the filter is performed. The development of impurities was divided into three stages. In the article for one case the trend line was presented. The article was completed conclusions.

scholarly journals COVID-19: A Therapeutic Approach Based on Pathophysiological Staging

2020 ◽  
Vol 14 (1) ◽  
pp. 32-37
Author(s):  
Christian Domingo Ribas
Keyword(s):  
Respiratory Failure ◽  
Therapeutic Approach ◽  
Distress Syndrome ◽  
The Other ◽  
Present Evidence ◽  
Respiratory Events ◽  
Therapeutic Decisions ◽  
Disease Staging ◽  
The One ◽  
Rule Out

The COVID-19 pandemic is a recently emerging problem. This has caused that the knowledge of the disease has been progressive and, therefore, the therapeutic decisions have been conditioned by this lack of knowledge on the one hand and by the therapeutic limitations on the other. Many published studies are methodologically weak and their conclusions, of limited value, have contributed to creating confusion on the therapeutic approach of the disease. In the present paper, we propose a therapeutic approach based on a new disease staging. The therapeutic approach is divided into two big sections: the pharmacological treatment for the phase of viral replication, cytokine storm or late respiratory events (which includes the adult respiratory distress syndrome (ARDS)) and the treatment of the respiratory failure In every stage, we discuss the pathophysiology and comment (accept or rule out) the pharmacological options according to the present evidence. Moreover, we indicate how respiratory failure should be treated. Some characteristics are based on the evidence found in the literature. Others are the result of my experience in other situations.

Multifidelity Recursive Cokriging for Dynamic Systems' Response Modification

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Luigi Bregant ◽  
Lucia Parussini ◽  
Valentino Pediroda
Keyword(s):  
Numerical Model ◽  
Numerical Simulations ◽  
Dynamic Systems ◽  
System Optimization ◽  
The Other ◽  
Experimental Measurements ◽  
Reciprocal Influence ◽  
Tests And Measurements ◽  
Invaluable Tool ◽  
Mixed Approach

In order to perform the accurate tuning of a machine and improve its performance to the requested tasks, the knowledge of the reciprocal influence among the system's parameters is of paramount importance to achieve the sought result with minimum effort and time. Numerical simulations are an invaluable tool to carry out the system optimization, but modeling limitations restrict the capabilities of this approach. On the other side, real tests and measurements are lengthy, expensive, and not always feasible. This is the reason why a mixed approach is presented in this work. The combination, through recursive cokriging, of low-fidelity, yet extensive, numerical model results, together with a limited number of highly accurate experimental measurements, allows to understand the dynamics of the machine in an extended and accurate way. The results of a controllable experiment are presented and the advantages and drawbacks of the proposed approach are also discussed.

scholarly journals Effect of ventilation rate on instilled surfactant distribution in the pulmonary airways of rats

2004 ◽  
Vol 97 (1) ◽  
pp. 45-56 ◽  
Author(s):  
Joseph C. Anderson ◽  
Robert C. Molthen ◽  
Christopher A. Dawson ◽  
Steve T. Haworth ◽  
Joseph L. Bull ◽  
...  
Keyword(s):  
Image Intensifier ◽  
Ventilation Rate ◽  
Exogenous Surfactant ◽  
Partial Liquid Ventilation ◽  
Liquid Distribution ◽  
Liquid Plug ◽  
Transport Dynamics ◽  
Surfactant Replacement Therapy ◽  
Pulmonary Airways ◽  
Uniform Liquid

Liquid can be instilled into the pulmonary airways during medical procedures such as surfactant replacement therapy, partial liquid ventilation, and pulmonary drug delivery. For all cases, understanding the dynamics of liquid distribution in the lung will increase the efficacy of treatment. A recently developed imaging technique for the study of real-time liquid transport dynamics in the pulmonary airways was used to investigate the effect of respiratory rate on the distribution of an instilled liquid, surfactant, in a rat lung. Twelve excised rat lungs were suspended vertically, and a single bolus (0.05 ml) of exogenous surfactant (Survanta, Ross Laboratories, Columbus, OH) mixed with radiopaque tracer was instilled as a plug into the trachea. The lungs were ventilated with a 4-ml tidal volume for 20 breaths at one of two respiratory rates: 20 or 60 breaths/min. The motion of radiodense surfactant was imaged at 30 frames/s with a microfocal X-ray source and an image intensifier. Dynamics of surfactant distribution were quantified for each image by use of distribution statistics and a homogeneity index. We found that the liquid distribution depended on the time to liquid plug rupture, which depends on ventilation rate. At 20 breaths/min, liquid was localized in the gravity-dependent region of the lung. At 60 breaths/min, the liquid coated the airways, providing a more vertically uniform liquid distribution.

Phytoplankton Productivity Changes in a Small, Double-Basin Lake in Response to Termination of Experimental Fertilization

1987 ◽  
Vol 44 (S1) ◽  
pp. s47-s54 ◽  
Author(s):  
J. A. Shearer ◽  
E. J. Fee ◽  
E. R. DeBruyn ◽  
D. R. DeClercq
Keyword(s):  
Numerical Model ◽  
Primary Production ◽  
The Other ◽  
Production Rates ◽  
Nitrogen And Phosphorus ◽  
Phytoplankton Productivity ◽  
Phytoplankton Primary Production ◽  
Carbon And Nitrogen ◽  
Model Technique ◽  
Reference Lakes

One basin of a small, double-basin lake was fertilized with carbon, nitrogen, and phosphorus for eight years, and then fertilization was stopped. The other basin was fertilized simultaneously with equivalent amounts of carbon and nitrogen only. Phytoplankton primary production was monitored using an incubator–numerical model technique. Production increased dramatically in the basin receiving artificial additions of C, N, and P. The increase was particularly large in the epilimnion where Cyanophyte blooms occurred during each year of fertilization and production rates averaged 2 to 10 times higher than in nearby, unfertilized reference lakes. Phosphorus, not nitrogen or carbon, was the critical nutrient. The productivity of the other basin also increased, but to a lesser degree and no Cyanophyte blooms were observed in this basin. When all fertilization was terminated, production in both basins immediately decreased. No more surface blooms were observed in either basin. Within 3 yr, the production had dropped to levels typical of reference lakes.

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