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Sample records for airway surface fluid

  1. Inhibition of airway surface fluid absorption by cholinergic stimulation

    PubMed Central

    Joo, Nam Soo; Krouse, Mauri E.; Choi, Jae Young; Cho, Hyung-Ju; Wine, Jeffrey J.

    2016-01-01

    In upper airways airway surface liquid (ASL) depth and clearance rates are both increased by fluid secretion. Secretion is opposed by fluid absorption, mainly via the epithelial sodium channel, ENaC. In static systems, increased fluid depth activates ENaC and decreased depth inhibits it, suggesting that secretion indirectly activates ENaC to reduce ASL depth. We propose an alternate mechanism in which cholinergic input, which causes copious airway gland secretion, also inhibits ENaC-mediated absorption. The conjoint action accelerates clearance, and the increased transport of mucus out of the airways restores ASL depth while cleansing the airways. We were intrigued by early reports of cholinergic inhibition of absorption by airways in some species. To reinvestigate this phenomenon, we studied inward short-circuit currents (Isc) in tracheal mucosa from human, sheep, pig, ferret, and rabbit and in two types of cultured cells. Basal Isc was inhibited 20–70% by the ENaC inhibitor, benzamil. Long-lasting inhibition of ENaC-dependent Isc was also produced by basolateral carbachol in all preparations except rabbit and the H441 cell line. Atropine inhibition produced a slow recovery or prevented inhibition if added before carbachol. The mechanism for inhibition was not determined and is most likely multi-factorial. However, its physiological significance is expected to be increased mucus clearance rates in cholinergically stimulated airways. PMID:26846701

  2. Surface fluid absorption and secretion in small airways

    PubMed Central

    Shamsuddin, A K M; Quinton, P M

    2012-01-01

    Native small airways must remain wet enough to be pliable and support ciliary clearance, but dry enough to remain patent for gas flow. The airway epithelial lining must both absorb and secrete ions to maintain a critical level of fluid on its surface. Despite frequent involvement in lung diseases, the minuscule size has limited studies of peripheral airways. To meet this challenge, we used a capillary to construct an Ussing chamber (area <1 mm2) to measure electrolyte transport across small native airways (∼1 mm ø) from pig lung. Transepithelial potentials (Vt) were recorded in open circuit conditions while applying constant current pulses across the luminal surface of dissected airways to calculate transepithelial electrical conductance (Gt) and equivalent short circuit current () in the presence and absence of selected Na+ and Cl− transport inhibitors (amiloride, GlyH-101, Niflumic acid) and agonists (Forskolin + IBMX, UTP). Considered together the responses suggest an organ composed of both secreting and absorbing epithelia that constitutively and concurrently transport fluids into and out of the airway, i.e. in opposite directions. Since the epithelial lining of small airways is arranged in long, accordion-like rows of pleats and folds that run axially down the lumen, we surmise that cells within the pleats are mainly secretory while the cells of the folds are principally absorptive. This structural arrangement could provide local fluid transport from within the pleats toward the luminal folds that may autonomously regulate the local surface fluid volume for homeostasis while permitting acute responses to maintain clearance. PMID:22547637

  3. Desiccation and hypertonicity of the airway surface fluid and thermally induced asthma.

    PubMed

    Kotaru, Chakradhar; Hejal, Rana B; Finigan, J H; Coreno, Albert J; Skowronski, Mary E; Brianas, Lori; McFadden, E R

    2003-01-01

    To determine whether drying and hypertonicity of the airway surface fluid (ASF) are involved in thermally induced asthma, nine subjects performed isocapnic hyperventilation (HV) (minute ventilation 62.2 +/- 8.3 l/min) of frigid air (-8.9 +/- 3.3 degrees C) while periciliary fluid was collected endoscopically from the trachea. Osmolality was measured by freezing-point depression. The baseline 1-s forced expiratory volume was 73 +/- 4% of predicted and fell 26.4% 10 min postchallenge (P > 0.0001). The volume of ASF collected was 11.0 +/- 2.2 microl at rest and remained constant during and after HV as the airways narrowed (HV 10.6 +/- 1.9, recovery 6.5 +/- 1.7 microl; P = 0.18). The osmolality also remained stable throughout (rest 336 +/- 16, HV 339 +/- 16, and recovery 352 +/- 19 mosmol/kgH(2)O, P = 0.76). These data demonstrate that airway desiccation and hypertonicity of the ASF do not develop during hyperpnea in asthma; therefore, other mechanisms must cause exercise- and hyperventilation-induced airflow limitation.

  4. Structure and function of airway surface layer of the human lungs & mobility of probe particles in complex fluids

    NASA Astrophysics Data System (ADS)

    Cai, Liheng

    Numerous infectious particles such as bacteria and pathogens are deposited on the airway surface of the human lungs during our daily breathing. To avoid infection the lung has evolved to develop a smart and powerful defense system called mucociliary clearance. The airway surface layer is a critical component of this mucus clearance system, which consists of two parts: (1) a mucus layer, that traps inhaled particles and transports them out of the lung by cilia-generated flow; and (2) a periciliary layer, that provides a favorable environment for ciliary beating and cell surface lubrication. For 75 years, it has been dogma that a single gel-like mucus layer, which is composed of secreted mucin glycoproteins, is transported over a "watery" periciliary layer. This one-gel model, however, does not explain fundamental features of the normal system, e.g. formation of a distinct mucus layer, nor accurately predict how the mucus clearance system fails in disease. In the first part of this thesis we propose a novel "Gel-on-Brush" model with a mucus layer (the "gel") and a "brush-like" periciliary layer, composed of mucins tethered to the luminal of airway surface, and supporting data accurately describes both the biophysical and cell biological bases for normal mucus clearance and its failure in disease. Our "Gel-on-Brush" model describes for the first time how and why mucus is efficiently cleared in health and unifies the pathogenesis of major human diseases, including cystic fibrosis and chronic obstructive pulmonary disease. It is expected that this "Gel-on-Brush" model of airway surface layer opens new directions for treatments of airway diseases. A dilemma regarding the function of mucus is that, although mucus traps any inhaled harmful particulates, it also poses a long-time problem for drug delivery: mobility of cargos carrying pharmaceutical agents is slowed down in mucus. The second part of this thesis aims to answer the question: can we theoretically understand the

  5. Fluid and electrolyte transport by cultured human airway epithelia.

    PubMed Central

    Smith, J J; Welsh, M J

    1993-01-01

    An understanding of the fluid and electrolyte transport properties of any epithelium requires knowledge of the direction, rate, and regulation of fluid transport and the composition of the fluid. Although human airway epithelial likely play a key role in controlling the quantity and composition of the respiratory tract fluid, evidence for such a role is not available. To obtain such knowledge, we measured fluid and electrolyte transport by cultured human nasal epithelia. Under basal conditions we found that epithelia absorbed Na+ and fluid; both processes were inhibited by addition of amiloride to the mucosal surface. These data suggest that active Na+ absorption is responsible for fluid absorption. Interestingly, Na+ absorption was not accompanied by the net absorption of Cl-; some other anion accompanied Na+. The combination of cAMP agonists and mucosal amiloride stimulated the secretion of NaCl-rich fluid. But surprisingly, the response to cAMP agonists in the absence of amiloride showed substantial intersubject variability: cAMP stimulated fluid secretion across some epithelia, for others, cAMP stimulated fluid absorption. The explanation for the differences in response is uncertain, but we speculate that the magnitude of apical membrane Na+ conductance may modulate the direction of fluid transport in response to cAMP. We also found that airway epithelial secrete H+ and absorb K+ under basal conditions; both processes were inhibited by cAMP agonists. Because the H+/K(+)-ATPase inhibitor, SCH 28080, inhibited K+ absorption, an apical membrane H+/K(+)-ATPase may be at least partly responsible for K+ and H+ transport. However, H+/K+ exchange could not entirely account for the luminal acidification. The finding that cAMP agonists inhibited luminal acidification may be explained by the recent finding that cAMP increases apical HCO3- conductance. These results provide new insights into how the intact airway epithelium may modify the composition of the respiratory

  6. Release of beryllium into artificial airway epithelial lining fluid.

    PubMed

    Stefaniak, Aleksandr B; Virji, M Abbas; Day, Gregory A

    2012-01-01

    Inhaled beryllium particles that deposit in the lung airway lining fluid may dissolve and interact with immune-competent cells resulting in sensitization. As such, solubilization of 17 beryllium-containing materials (ore, hydroxide, metal, oxide, alloys, and process intermediates) was investigated using artificial human airway epithelial lining fluid. The maximum beryllium release in 7 days was 11.78% (from a beryl ore melter dust), although release from most materials was < 1%. Calculated dissolution half-times ranged from 30 days (reduction furnace material) to 74,000 days (hydroxide). Despite rapid mechanical clearance, billions of beryllium ions may be released in the respiratory tract via dissolution in airway lining fluid. Beryllium-containing particles that deposit in the respiratory tract dissolve in artificial lung epithelial lining fluid, thereby providing ions for absorption in the lung and interaction with immune-competent cells in the respiratory tract.

  7. Two layer fluid stress analysis during airway closure

    NASA Astrophysics Data System (ADS)

    Tai, Cheng-Feng; Halpern, David; Grotberg, James

    2009-11-01

    The airways are lined with a film consisting of two immiscible liquids, a serous layer and a more viscous mucus layer. Due to a surface tension driven instability, a liquid plug can form that obstructs the passage of air along the airways provided the ratio of the film thickness to the tube radius is greater than a critical value ˜0.12. In this study, we assume that the liquid layers are Newtonian, the surface tension is constant at the interfaces and the air-core phase is passive. We solve the Navier-Stokes and continuity equations subject to interfacial stress conditions and kinematic boundary conditions numerically using a finite volume approach in conjunction with a sharp interface method for the interfaces. Surface tension, viscosity and film thickness ratios can be altered by disease, and their influence on the closure instability is investigated. Results show that the shear and normal stresses along the airway walls can be strong enough to injure airway epithelial cells. We acknowledge support from the National Institutes of Health grant number NIH HL85156.

  8. Airway wall stiffening increases peak wall shear stress: a fluid-structure interaction study in rigid and compliant airways.

    PubMed

    Xia, Guohua; Tawhai, Merryn H; Hoffman, Eric A; Lin, Ching-Long

    2010-05-01

    The airflow characteristics in a computed tomography (CT) based human airway bifurcation model with rigid and compliant walls are investigated numerically. An in-house three-dimensional (3D) fluid-structure interaction (FSI) method is applied to simulate the flow at different Reynolds numbers and airway wall stiffness. As the Reynolds number increases, the airway wall deformation increases and the secondary flow becomes more prominent. It is found that the peak wall shear stress on the rigid airway wall can be five times stronger than that on the compliant airway wall. When adding tethering forces to the model, we find that these forces, which produce larger airway deformation than without tethering, lead to more skewed velocity profiles in the lower branches and further reduced wall shear stresses via a larger airway lumen. This implies that pathologic changes in the lung such as fibrosis or remodeling of the airway wall-both of which can serve to restrain airway wall motion-have the potential to increase wall shear stress and thus can form a positive feed-back loop for the development of altered flow profiles and airway remodeling. These observations are particularly interesting as we try to understand flow and structural changes seen in, for instance, asthma, emphysema, cystic fibrosis, and interstitial lung disease.

  9. Numerical simulation of soft palate movement and airflow in human upper airway by fluid-structure interaction method

    NASA Astrophysics Data System (ADS)

    Sun, Xiuzhen; Yu, Chi; Wang, Yuefang; Liu, Yingxi

    2007-08-01

    In this paper, the authors present airflow field characteristics of human upper airway and soft palate movement attitude during breathing. On the basis of the data taken from the spiral computerized tomography images of a healthy person and a patient with Obstructive Sleep Apnea-Hypopnea Syndrome (OSAHS), three-dimensional models of upper airway cavity and soft palate are reconstructed by the method of surface rendering. Numerical simulation is performed for airflow in the upper airway and displacement of soft palate by fluid-structure interaction analysis. The reconstructed three-dimensional models precisely preserve the original configuration of upper airways and soft palate. The results of the pressure and velocity distributions in the airflow field are quantitatively determined, and the displacement of soft palate is presented. Pressure gradients of airway are lower for the healthy person and the airflow distribution is quite uniform in the case of free breathing. However, the OSAHS patient remarkably escalates both the pressure and velocity in the upper airway, and causes higher displacement of the soft palate. The present study is useful in revealing pathogenesis and quantitative mutual relationship between configuration and function of the upper airway as well as in diagnosing diseases related to anatomical structure and function of the upper airway.

  10. Computational analysis of microbubble flows in bifurcating airways: role of gravity, inertia, and surface tension.

    PubMed

    Chen, Xiaodong; Zielinski, Rachel; Ghadiali, Samir N

    2014-10-01

    Although mechanical ventilation is a life-saving therapy for patients with severe lung disorders, the microbubble flows generated during ventilation generate hydrodynamic stresses, including pressure and shear stress gradients, which damage the pulmonary epithelium. In this study, we used computational fluid dynamics to investigate how gravity, inertia, and surface tension influence both microbubble flow patterns in bifurcating airways and the magnitude/distribution of hydrodynamic stresses on the airway wall. Direct interface tracking and finite element techniques were used to simulate bubble propagation in a two-dimensional (2D) liquid-filled bifurcating airway. Computational solutions of the full incompressible Navier-Stokes equation were used to investigate how inertia, gravity, and surface tension forces as characterized by the Reynolds (Re), Bond (Bo), and Capillary (Ca) numbers influence pressure and shear stress gradients at the airway wall. Gravity had a significant impact on flow patterns and hydrodynamic stress magnitudes where Bo > 1 led to dramatic changes in bubble shape and increased pressure and shear stress gradients in the upper daughter airway. Interestingly, increased pressure gradients near the bifurcation point (i.e., carina) were only elevated during asymmetric bubble splitting. Although changes in pressure gradient magnitudes were generally more sensitive to Ca, under large Re conditions, both Re and Ca significantly altered the pressure gradient magnitude. We conclude that inertia, gravity, and surface tension can all have a significant impact on microbubble flow patterns and hydrodynamic stresses in bifurcating airways.

  11. Measurement of the Airway Surface Liquid Volume with Simple Light Refraction Microscopy

    PubMed Central

    Harvey, Peter R.; Tarran, Robert; Garoff, Stephen

    2011-01-01

    In the cystic fibrosis (CF) lung, the airway surface liquid (ASL) volume is depleted, impairing mucus clearance from the lung and leading to chronic airway infection and obstruction. Several therapeutics have been developed that aim to restore normal airway surface hydration to the CF airway, yet preclinical evaluation of these agents is hindered by the paucity of methods available to directly measure the ASL. Therefore, we sought to develop a straightforward approach to measure the ASL volume that would serve as the basis for a standardized method to assess mucosal hydration using readily available resources. Primary human bronchial epithelial (HBE) cells cultured at an air–liquid interface develop a liquid meniscus at the edge of the culture. We hypothesized that the size of the fluid meniscus is determined by the ASL volume, and could be measured as an index of the epithelial surface hydration status. A simple method was developed to measure the volume of fluid present in meniscus by imaging the refraction of light at the ASL interface with the culture wall using low-magnification microscopy. Using this method, we found that primary CF HBE cells had a reduced ASL volume compared with non-CF HBE cells, and that known modulators of ASL volume caused the predicted responses. Thus, we have demonstrated that this method can detect physiologically relevant changes in the ASL volume, and propose that this novel approach may be used to rapidly assess the effects of airway hydration therapies in high-throughput screening assays. PMID:21239602

  12. AMPK agonists ameliorate sodium and fluid transport and inflammation in cystic fibrosis airway epithelial cells.

    PubMed

    Myerburg, Michael M; King, J Darwin; Oyster, Nicholas M; Fitch, Adam C; Magill, Amy; Baty, Catherine J; Watkins, Simon C; Kolls, Jay K; Pilewski, Joseph M; Hallows, Kenneth R

    2010-06-01

    The metabolic sensor AMP-activated kinase (AMPK) inhibits both the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) Cl(-) channel and epithelial Na(+) channel (ENaC), and may inhibit secretion of proinflammatory cytokines in epithelia. Here we have tested in primary polarized CF and non-CF human bronchial epithelial (HBE) cells the effects of AMPK activators, metformin and 5-aminoimidazole-4-carboxamide-1-beta-D-riboside (AICAR), on various parameters that contribute to CF lung disease: ENaC-dependent short-circuit currents (I(sc)), airway surface liquid (ASL) height, and proinflammatory cytokine secretion. AMPK activation after overnight treatment with either metformin (2-5 mM) or AICAR (1 mM) substantially inhibited ENaC-dependent I(sc) in both CF and non-CF airway cultures. Live-cell confocal images acquired 60 minutes after apical addition of Texas Red-dextran-containing fluid revealed significantly greater ASL heights after AICAR and metformin treatment relative to controls, suggesting that AMPK-dependent ENaC inhibition slows apical fluid reabsorption. Both metformin and AICAR decreased secretion of various proinflammatory cytokines, both with and without prior LPS stimulation. Finally, prolonged exposure to more physiologically relevant concentrations of metformin (0.03-1 mM) inhibited ENaC currents and decreased proinflammatory cytokine levels in CF HBE cells in a dose-dependent manner. These findings suggest that novel therapies to activate AMPK in the CF airway may be beneficial by blunting excessive sodium and ASL absorption and by reducing excessive airway inflammation, which are major contributors to CF lung disease.

  13. AMPK Agonists Ameliorate Sodium and Fluid Transport and Inflammation in Cystic Fibrosis Airway Epithelial Cells

    PubMed Central

    Myerburg, Michael M.; King, J Darwin; Oyster, Nicholas M.; Fitch, Adam C.; Magill, Amy; Baty, Catherine J.; Watkins, Simon C.; Kolls, Jay K.; Pilewski, Joseph M.; Hallows, Kenneth R.

    2010-01-01

    The metabolic sensor AMP-activated kinase (AMPK) inhibits both the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) Cl− channel and epithelial Na+ channel (ENaC), and may inhibit secretion of proinflammatory cytokines in epithelia. Here we have tested in primary polarized CF and non-CF human bronchial epithelial (HBE) cells the effects of AMPK activators, metformin and 5-aminoimidazole-4-carboxamide-1-β-D-riboside (AICAR), on various parameters that contribute to CF lung disease: ENaC-dependent short-circuit currents (Isc), airway surface liquid (ASL) height, and proinflammatory cytokine secretion. AMPK activation after overnight treatment with either metformin (2–5 mM) or AICAR (1 mM) substantially inhibited ENaC-dependent Isc in both CF and non-CF airway cultures. Live-cell confocal images acquired 60 minutes after apical addition of Texas Red–dextran-containing fluid revealed significantly greater ASL heights after AICAR and metformin treatment relative to controls, suggesting that AMPK-dependent ENaC inhibition slows apical fluid reabsorption. Both metformin and AICAR decreased secretion of various proinflammatory cytokines, both with and without prior LPS stimulation. Finally, prolonged exposure to more physiologically relevant concentrations of metformin (0.03–1 mM) inhibited ENaC currents and decreased proinflammatory cytokine levels in CF HBE cells in a dose-dependent manner. These findings suggest that novel therapies to activate AMPK in the CF airway may be beneficial by blunting excessive sodium and ASL absorption and by reducing excessive airway inflammation, which are major contributors to CF lung disease. PMID:19617399

  14. Thick airway surface liquid volume and weak mucin expression in pendrin-deficient human airway epithelia

    PubMed Central

    Lee, Hyun Jae; Yoo, Jee Eun; Namkung, Wan; Cho, Hyung-Ju; Kim, Kyubo; Kang, Joo Wan; Yoon, Joo-Heon; Choi, Jae Young

    2015-01-01

    Pendrin is an anion exchanger whose mutations are known to cause hearing loss. However, recent data support the linkage between pendrin expression and airway diseases, such as asthma. To evaluate the role of pendrin in the regulation of the airway surface liquid (ASL) volume and mucin expression, we investigated the function and expression of pendrin and ion channels and anion exchangers. Human nasal epithelial cells were cultured from 16 deaf patients carrying pendrin mutations (DFNB4) and 17 controls. The cells were treated with IL-13 to induce mucus hypersecretion. Airway surface liquid thickness was measured and real-time polymerase chain reaction was performed targeting various transporters and MUC5AC. Anion exchanger activity was measured using a pH-sensitive fluorescent probe. Periodic acid-Schiff staining was performed on the cultured cells and inferior turbinate tissues. The ASL layer of the nasal epithelia from DFNB4 subjects was thicker than the controls, and the difference became more prominent following IL-13 stimulation. There was no difference in anion exchange activity after IL-13 treatment in the cells from DFNB4 patients, while it increased in the controls. Goblet cell metaplasia induced by IL-13 treatment seen in the controls was not observed in the DFNB4 cells. Furthermore, the periodic acid-Schiff staining-positive area was lesser in the inferior turbinate tissues from DFNB4 patients that those from controls. Pendrin plays a critical role in ASL volume regulation and mucin expression as pendrin-deficient airway epithelial cells are refractory to stimulation with IL-13. Specific blockers targeting pendrin in the airways may therefore have therapeutic potential in the treatment of allergic airway diseases. PMID:26243215

  15. Automatic construction of subject-specific human airway geometry including trifurcations based on a CT-segmented airway skeleton and surface.

    PubMed

    Miyawaki, Shinjiro; Tawhai, Merryn H; Hoffman, Eric A; Wenzel, Sally E; Lin, Ching-Long

    2017-04-01

    We propose a method to construct three-dimensional airway geometric models based on airway skeletons, or centerlines (CLs). Given a CT-segmented airway skeleton and surface, the proposed CL-based method automatically constructs subject-specific models that contain anatomical information regarding branches, include bifurcations and trifurcations, and extend from the trachea to terminal bronchioles. The resulting model can be anatomically realistic with the assistance of an image-based surface; alternatively a model with an idealized skeleton and/or branch diameters is also possible. This method systematically identifies and classifies trifurcations to successfully construct the models, which also provides the number and type of trifurcations for the analysis of the airways from an anatomical point of view. We applied this method to 16 normal and 16 severe asthmatic subjects using their computed tomography images. The average distance between the surface of the model and the image-based surface was 11 % of the average voxel size of the image. The four most frequent locations of trifurcations were the left upper division bronchus, left lower lobar bronchus, right upper lobar bronchus, and right intermediate bronchus. The proposed method automatically constructed accurate subject-specific three-dimensional airway geometric models that contain anatomical information regarding branches using airway skeleton, diameters, and image-based surface geometry. The proposed method can construct (i) geometry automatically for population-based studies, (ii) trifurcations to retain the original airway topology, (iii) geometry that can be used for automatic generation of computational fluid dynamics meshes, and (iv) geometry based only on a skeleton and diameters for idealized branches.

  16. Nucleotide release provides a mechanism for airway surface liquid homeostasis.

    PubMed

    Lazarowski, Eduardo R; Tarran, Robert; Grubb, Barbara R; van Heusden, Catharina A; Okada, Seiko; Boucher, Richard C

    2004-08-27

    Nucleotides within the airway surface liquid (ASL) regulate airway epithelial ion transport rates by Ca(2+) -and protein kinase C-dependent mechanisms via activation of specific P2Y receptors. Extracellular adenine nucleotides also serve as precursors for adenosine, which promotes cyclic AMP-mediated activation of the cystic fibrosis transmembrane regulator chloride channel via A(2b) adenosine receptors. A biological role for extracellular ATP in ASL volume homeostasis has been suggested by the demonstration of regulated ATP release from airway epithelia. However, nucleotide hydrolysis at the airway surface makes it difficult to assess the magnitude of ATP release and the relative abundance of adenyl purines and, hence, to define their biological functions. We have combined ASL microsampling and high performance liquid chromatography analysis of fluorescent 1,N(6)-ethenoadenine derivatives to measure adenyl purines in ASL. We found that adenosine, AMP, and ADP accumulated in high concentrations relative to ATP within the ASL covering polarized primary human normal or cystic fibrosis airway epithelial cells. By using immortalized epithelial cell monolndogenayers that eously express a luminal A(2b) adenosine receptor, we found that basal as well asforskolin-promoted cyclic AMP production was reduced by exogenous adenosine deaminase, suggesting that A(2b) receptors sense endogenous adenosine within the ASL. The physiological role of adenosine was further established by illustrating that adenosine removal or inhibition of adenosine receptors in primary cultures impaired ASL volume regulation. Our data reveal a complex pattern of nucleotides/nucleosides in ASL under resting conditions and suggest that adenosine may play a key role in regulating ASL volume homeostasis.

  17. Nucleotide Release Provides a Mechanism for Airway Surface Liquid Homeostasis*

    PubMed Central

    Lazarowski, Eduardo R.; Tarran, Robert; Grubb, Barbara R.; van Heusden, Catharina A.; Okada, Seiko; Boucher, Richard C.

    2010-01-01

    Nucleotides within the airway surface liquid (ASL) regulate airway epithelial ion transport rates by Ca2+- and protein kinase C-dependent mechanisms via activation of specific P2Y receptors. Extracellular adenine nucleotides also serve as precursors for adenosine, which promotes cyclic AMP-mediated activation of the cystic fibrosis transmembrane regulator chloride channel via A2b adenosine receptors. A biological role for extracellular ATP in ASL volume homeostasis has been suggested by the demonstration of regulated ATP release from airway epithelia. However, nucleotide hydrolysis at the airway surface makes it difficult to assess the magnitude of ATP release and the relative abundance of adenyl purines and, hence, to define their biological functions. We have combined ASL microsampling and high performance liquid chromatography analysis of fluorescent 1,N6-ethenoadenine derivatives to measure adenyl purines in ASL. We found that adenosine, AMP, and ADP accumulated in high concentrations relative to ATP within the ASL covering polarized primary human normal or cystic fibrosis airway epithelial cells. By using immortalized epithelial cell monolayers that endogenously express a luminal A2b adenosine receptor, we found that basal as well as forskolin-promoted cyclic AMP production was reduced by exogenous adenosine deaminase, suggesting that A2b receptors sense endogenous adenosine within the ASL. The physiological role of adenosine was further established by illustrating that adenosine removal or inhibition of adenosine receptors in primary cultures impaired ASL volume regulation. Our data reveal a complex pattern of nucleotides/nucleosides in ASL under resting conditions and suggest that adenosine may play a key role in regulating ASL volume homeostasis. PMID:15210701

  18. Computational Fluid Dynamics Modeling of Bacillus anthracis Spore Deposition in Rabbit and Human Respiratory Airways

    SciTech Connect

    Kabilan, Senthil; Suffield, Sarah R.; Recknagle, Kurtis P.; Jacob, Rick E.; Einstein, Daniel R.; Kuprat, Andrew P.; Carson, James P.; Colby, Sean M.; Saunders, James H.; Hines, Stephanie; Teeguarden, Justin G.; Straub, Tim M.; Moe, M.; Taft, Sarah; Corley, Richard A.

    2016-09-30

    Three-dimensional computational fluid dynamics and Lagrangian particle deposition models were developed to compare the deposition of aerosolized Bacillus anthracis spores in the respiratory airways of a human with that of the rabbit, a species commonly used in the study of anthrax disease. The respiratory airway geometries for each species were derived from computed tomography (CT) or µCT images. Both models encompassed airways that extended from the external nose to the lung with a total of 272 outlets in the human model and 2878 outlets in the rabbit model. All simulations of spore deposition were conducted under transient, inhalation-exhalation breathing conditions using average species-specific minute volumes. The highest exposure concentration was modeled in the rabbit based upon prior acute inhalation studies. For comparison, human simulation was also conducted at the same concentration. Results demonstrated that regional spore deposition patterns were sensitive to airway geometry and ventilation profiles. Due to the complex airway geometries in the rabbit nose, higher spore deposition efficiency was predicted in the upper conducting airways compared to the human at the same air concentration of anthrax spores. As a result, higher particle deposition was predicted in the conducting airways and deep lung of the human compared to the rabbit lung due to differences in airway branching pattern. This information can be used to refine published and ongoing biokinetic models of inhalation anthrax spore exposures, which currently estimate deposited spore concentrations based solely upon exposure concentrations and inhaled doses that do not factor in species-specific anatomy and physiology.

  19. Sialic acid-to-urea ratio as a measure of airway surface hydration.

    PubMed

    Esther, Charles R; Hill, David B; Button, Brian; Shi, Shuai; Jania, Corey; Duncan, Elizabeth A; Doerschuk, Claire M; Chen, Gang; Ranganathan, Sarath; Stick, Stephen M; Boucher, Richard C

    2017-03-01

    Although airway mucus dehydration is key to pathophysiology of cystic fibrosis (CF) and other airways diseases, measuring mucus hydration is challenging. We explored a robust method to estimate mucus hydration using sialic acid as a marker for mucin content. Terminal sialic acid residues from mucins were cleaved by acid hydrolysis from airway samples, and concentrations of sialic acid, urea, and other biomarkers were analyzed by mass spectrometry. In mucins purified from human airway epithelial (HAE), sialic acid concentrations after acid hydrolysis correlated with mucin concentrations (r(2) = 0.92). Sialic acid-to-urea ratios measured from filters applied to the apical surface of cultured HAE correlated to percent solids and were elevated in samples from CF HAEs relative to controls (2.2 ± 1.1 vs. 0.93 ± 1.8, P < 0.01). Sialic acid-to-urea ratios were elevated in bronchoalveolar lavage fluid (BALF) from β-epithelial sodium channel (ENaC) transgenic mice, known to have reduced mucus hydration, and mice sensitized to house dust mite allergen. In a translational application, elevated sialic acid-to-urea ratios were measured in BALF from young children with CF who had airway infection relative to those who did not (5.5 ± 3.7 vs. 1.9 ± 1.4, P < 0.02) and could be assessed simultaneously with established biomarkers of inflammation. The sialic acid-to-urea ratio performed similarly to percent solids, the gold standard measure of mucus hydration. The method proved robust and has potential to serve as flexible techniques to assess mucin hydration, particularly in samples like BALF in which established methods such as percent solids cannot be utilized.

  20. Validation of computational fluid dynamics methodology used for human upper airway flow simulations.

    PubMed

    Mylavarapu, Goutham; Murugappan, Shanmugam; Mihaescu, Mihai; Kalra, Maninder; Khosla, Sid; Gutmark, Ephraim

    2009-07-22

    An anatomically accurate human upper airway model was constructed from multiple magnetic resonance imaging axial scans. This model was used to conduct detailed Computational Fluid Dynamics (CFD) simulations during expiration, to investigate the fluid flow in the airway regions where obstruction could occur. An identical physical model of the same airway was built using stereo lithography. Pressure and velocity measurements were conducted in the physical model. Both simulations and experiments were performed at a peak expiratory flow rate of 200 L/min. Several different numerical approaches within the FLUENT commercial software framework were used in the simulations; unsteady Large Eddy Simulation (LES), steady Reynolds-Averaged Navier-Stokes (RANS) with two-equation turbulence models (i.e. k-epsilon, standard k-omega, and k-omega Shear Stress Transport (SST)) and with one-equation Spalart-Allmaras model. The CFD predictions of the average wall static pressures at different locations along the airway wall were favorably compared with the experimental data. Among all the approaches, standard k-omega turbulence model resulted in the best agreement with the static pressure measurements, with an average error of approximately 20% over all ports. The highest positive pressures were observed in the retroglossal regions below the epiglottis, while the lowest negative pressures were recorded in the retropalatal region. The latter is a result of the airflow acceleration in the narrow retropalatal region. The largest pressure drop was observed at the tip of the soft palate. This location has the smallest cross section of the airway. The good agreement between the computations and the experimental results suggest that CFD simulations can be used to accurately compute aerodynamic flow characteristics of the upper airway.

  1. Computational fluid dynamics modeling of Bacillus anthracis spore deposition in rabbit and human respiratory airways

    SciTech Connect

    Kabilan, S.; Suffield, S. R.; Recknagle, K. P.; Jacob, R. E.; Einstein, D. R.; Kuprat, A. P.; Carson, J. P.; Colby, S. M.; Saunders, J. H.; Hines, S. A.; Teeguarden, J. G.; Straub, T. M.; Moe, M.; Taft, S. C.; Corley, R. A.

    2016-09-01

    Three-dimensional computational fluid dynamics and Lagrangian particle deposition models were developed to compare the deposition of aerosolized Bacillus anthracis spores in the respiratory airways of a human with that of the rabbit, a species commonly used in the study of anthrax disease. The respiratory airway geometries for each species were derived respectively from computed tomography (CT) and µCT images. Both models encompassed airways that extended from the external nose to the lung with a total of 272 outlets in the human model and 2878 outlets in the rabbit model. All simulations of spore deposition were conducted under transient, inhalation–exhalation breathing conditions using average species-specific minute volumes. Two different exposure scenarios were modeled in the rabbit based upon experimental inhalation studies. For comparison, human simulations were conducted at the highest exposure concentration used during the rabbit experimental exposures. Results demonstrated that regional spore deposition patterns were sensitive to airway geometry and ventilation profiles. Due to the complex airway geometries in the rabbit nose, higher spore deposition efficiency was predicted in the nasal sinus compared to the human at the same air concentration of anthrax spores. In contrast, higher spore deposition was predicted in the lower conducting airways of the human compared to the rabbit lung due to differences in airway branching pattern. This information can be used to refine published and ongoing biokinetic models of inhalation anthrax spore exposures, which currently estimate deposited spore concentrations based solely upon exposure concentrations and inhaled doses that do not factor in species-specific anatomy and physiology for deposition.

  2. Airway Microbiota in Bronchoalveolar Lavage Fluid from Clinically Well Infants with Cystic Fibrosis

    PubMed Central

    Wagner, Brandie D.; Williams, Cynthia B.; Stevens, Mark J.; Robertson, Charles E.; Welchlin, Cole W.; Moen, Catherine E.; Zemanick, Edith T.; Harris, Jonathan K.

    2016-01-01

    Background Upper airway cultures guide the identification and treatment of lung pathogens in infants with cystic fibrosis (CF); however, this may not fully reflect the spectrum of bacteria present in the lower airway. Our objectives were to characterize the airway microbiota using bronchoalveolar lavage fluid (BALF) from asymptomatic CF infants during the first year of life and to investigate the relationship between BALF microbiota, standard culture and clinical characteristics. Methods BALF, nasopharyngeal (NP) culture and infant pulmonary function testing data were collected at 6 months and one year of age during periods of clinical stability from infants diagnosed with CF by newborn screening. BALF was analyzed for total bacterial load by qPCR and for bacterial community composition by 16S ribosomal RNA sequencing. Clinical characteristics and standard BALF and NP culture results were recorded over five years of longitudinal follow-up. Results 12 BALF samples were collected from 8 infants with CF. Streptococcus, Burkholderia, Prevotella, Haemophilus, Porphyromonas, and Veillonella had the highest median relative abundance in infant CF BALF. Two of the 3 infants with repeat BALF had changes in their microbial communities over six months (Morisita-Horn diversity index 0.36, 0.38). Although there was excellent percent agreement between standard NP and BALF cultures, these techniques did not routinely detect all bacteria identified by sequencing. Conclusions BALF in asymptomatic CF infants contains complex microbiota, often missed by traditional culture of airway secretions. Anaerobic bacteria are commonly found in the lower airways of CF infants. PMID:27930727

  3. In situ measurement of airway surface liquid [K+] using a ratioable K+-sensitive fluorescent dye.

    PubMed

    Namkung, Wan; Song, Yuanlin; Mills, Aaron D; Padmawar, Prashant; Finkbeiner, Walter E; Verkman, A S

    2009-06-05

    The airway surface liquid (ASL) is the thin fluid layer lining airway surface epithelial cells, whose volume and composition are tightly regulated and may be abnormal in cystic fibrosis (CF). We synthesized a two-color fluorescent dextran to measure ASL [K(+)], TAC-Lime-dextran-TMR, consisting of a green-fluorescing triazacryptand K(+) ionophore-Bodipy conjugate, coupled to dextran, together with a red fluorescing tetramethylrhodamine reference chromophore. TAC-Lime-dextran-TMR fluorescence was K(+)-selective, increasing >4-fold with increasing [K(+)] from 0 to 40 mm. In well differentiated human airway epithelial cells, ASL [K(+)] was 20.8 +/- 0.3 mm and decreased by inhibition of the Na(+)/K(+) pump (ouabain), ENaC (amiloride), CF transmembrane conductance regulator (CFTR(inh)-172), or K(+) channels (TEA or XE991). ASL [K(+)] was increased by forskolin but not affected by Na(+)/K(+)/2Cl(-) cotransporter inhibition (bumetanide). Functional and expression studies indicated the involvement of [K(+)] channels KCNQ1, KCNQ3, and KCNQ5 as determinants of ASL [K(+)]. [K(+)] in CF cultures was similar to that in non-CF cultures, suggesting that abnormal ASL [K(+)] is not a factor in CF lung disease. In intact airways, ASL [K(+)] was also well above extracellular [K(+)]: 22 +/- 1 mm in pig trachea ex vivo and 16 +/- 1 mm in mouse trachea in vivo. Our results provide the first noninvasive measurements of [K(+)] in the ASL and indicate the involvement of apical and basolateral membrane ion transporters in maintaining a high ASL [K(+)].

  4. Regulation of airway surface liquid volume and mucus transport by active ion transport.

    PubMed

    Tarran, Robert

    2004-01-01

    Mucus clearance is an important component of the lung's innate defense against disease, and the ability of the airways to clear mucus is strongly dependent on the volume of liquid on airway surfaces. Whether airway surface liquid (ASL) volume is maintained by passive surface forces or by active ion transport is controversial yet crucial to the understanding of how this system operates in both health and disease. In support of active ion transport being the major determinant of ASL volume, we have demonstrated that normal airway epithelia sense and autoregulate ASL height (volume) by adjusting the rates of Na+ absorption and Cl- secretion to maintain mucus transport.

  5. Airflow behavior changes in upper airway caused by different head and neck positions: Comparison by computational fluid dynamics.

    PubMed

    Wei, Wei; Huang, Shi-Wei; Chen, Lian-Hua; Qi, Yang; Qiu, Yi-Min; Li, Shi-Tong

    2017-02-08

    The feasibility of computational fluid dynamics (CFD) to evaluate airflow characteristics in different head and neck positions has not been established. This study compared the changes in volume and airflow behavior of the upper airway by CFD simulation to predict the influence of anatomical and physiological airway changes due to different head-neck positions on mechanical ventilation. One awake volunteer with no risk of difficult airway underwent computed tomography in neutral position, extension position (both head and neck extended), and sniffing position (head extended and neck flexed). Three-dimensional airway models of the upper airway were reconstructed. The total volume (V) and narrowest area (Amin) of the airway models were measured. CFD simulation with an Spalart-Allmaras model was performed to characterize airflow behavior in neutral, extension, and sniffing positions of closed-mouth and open-mouth ventilation. The comparison result for V was neutral airway patency by increasing airway volume and decreasing airway resistance, suggesting that sniffing position may be the optimal choice for mask ventilation.

  6. Computational Fluid Dynamic Analysis of the Posterior Airway Space After Maxillomandibular Advancement For Obstructive Sleep Apnea Syndrome

    PubMed Central

    Sittitavornwong, Somsak; Waite, Peter D.; Shih, Alan M.; Cheng, Gary C.; Koomullil, Roy; Ito, Yasushi; Cure, Joel K; Harding, Susan M.; Litaker, Mark

    2013-01-01

    Purpose Evaluate the soft tissue change of the upper airway after maxillomandibular advancement (MMA) by computational fluid dynamics (CFD). Materials and Methods Eight OSAS patients who required MMA were recruited into this study. All participants had pre- and post-operative computed tomography (CT) and underwent MMA by a single oral and maxillofacial surgeon. Upper airway CT data sets for these 8 participants were created with high-fidelity 3-D numerical models for computational fluid dynamics (CFD). The 3-D models were simulated and analyzed to study how changes in airway anatomy affects pressure effort required for normal breathing. Airway dimensions, skeletal changes, Apnea-Hypopnea Index (AHI), and pressure efforts of pre- and post-operative 3-D models were compared and correlations interpreted. Results After MMA, laminar and turbulent air flow was significantly decreased at every level of the airway. The cross-sectional areas at the soft palate and tongue base were significantly increased. Conclusions This study shows that MMA increases airway dimensions by the increasing the occipital base (Base) - pogonion (Pg) distance. An increase of the Base-Pg distance showed a significant correlation with an AHI improvement and a decreased pressure effort of the upper airway. Decreasing the pressure effort will decrease the breathing workload. This improves the condition of OSAS. PMID:23642544

  7. Free DNA in Cystic Fibrosis Airway Fluids Correlates with Airflow Obstruction

    PubMed Central

    Marcos, Veronica; Zhou-Suckow, Zhe; Önder Yildirim, Ali; Bohla, Alexander; Hector, Andreas; Vitkov, Ljubomir; Krautgartner, Wolf Dietrich; Stoiber, Walter; Griese, Matthias; Eickelberg, Oliver; Mall, Marcus A.; Hartl, Dominik

    2015-01-01

    Chronic obstructive lung disease determines morbidity and mortality of patients with cystic fibrosis (CF). CF airways are characterized by a nonresolving neutrophilic inflammation. After pathogen contact or prolonged activation, neutrophils release DNA fibres decorated with antimicrobial proteins, forming neutrophil extracellular traps (NETs). NETs have been described to act in a beneficial way for innate host defense by bactericidal, fungicidal, and virucidal actions. On the other hand, excessive NET formation has been linked to the pathogenesis of autoinflammatory and autoimmune disease conditions. We quantified free DNA structures characteristic of NETs in airway fluids of CF patients and a mouse model with CF-like lung disease. Free DNA levels correlated with airflow obstruction, fungal colonization, and CXC chemokine levels in CF patients and CF-like mice. When viewed in combination, our results demonstrate that neutrophilic inflammation in CF airways is associated with abundant free DNA characteristic for NETosis, and suggest that free DNA may be implicated in lung function decline in patients with CF. PMID:25918476

  8. Hypercapnia modulates cAMP signalling and cystic fibrosis transmembrane conductance regulator‐dependent anion and fluid secretion in airway epithelia

    PubMed Central

    Turner, Mark J.; Saint‐Criq, Vinciane; Patel, Waseema; Ibrahim, Salam H.; Verdon, Bernard; Ward, Christopher; Garnett, James P.; Tarran, Robert; Cann, Martin J.

    2015-01-01

    Key points Raised arterial blood CO2 (hypercapnia) is a feature of many lung diseases.CO2 has been shown to act as a cell signalling molecule in human cells, notably by influencing the levels of cell signalling second messengers: cAMP and Ca2+.Hypercapnia reduced cAMP‐stimulated cystic fibrosis transmembrane conductance regulator‐dependent anion and fluid transport in Calu‐3 cells and primary human airway epithelia but did not affect cAMP‐regulated HCO3 − transport via pendrin or Na+/HCO3 − cotransporters.These results further support the role of CO2 as a cell signalling molecule and suggests CO2‐induced reductions in airway anion and fluid transport may impair innate defence mechanisms of the lungs. Abstract Hypercapnia is clinically defined as an arterial blood partial pressure of CO2 of above 40 mmHg and is a feature of chronic lung disease. In previous studies we have demonstrated that hypercapnia modulates agonist‐stimulated cAMP levels through effects on transmembrane adenylyl cyclase activity. In the airways, cAMP is known to regulate cystic fibrosis transmembrane conductance regulator (CFTR)‐mediated anion and fluid secretion, which contributes to airway surface liquid homeostasis. The aim of the current work was to investigate if hypercapnia could modulate cAMP‐regulated ion and fluid transport in human airway epithelial cells. We found that acute exposure to hypercapnia significantly reduced forskolin‐stimulated elevations in intracellular cAMP as well as both adenosine‐ and forskolin‐stimulated increases in CFTR‐dependent transepithelial short‐circuit current, in polarised cultures of Calu‐3 human airway cells. This CO2‐induced reduction in anion secretion was not due to a decrease in HCO3 − transport given that neither a change in CFTR‐dependent HCO3 − efflux nor Na+/HCO3 − cotransporter‐dependent HCO3 − influx were CO2‐sensitive. Hypercapnia also reduced the volume of forskolin‐stimulated fluid

  9. Surface cleanliness of fluid systems, specification for

    NASA Technical Reports Server (NTRS)

    1995-01-01

    This specification establishes surface cleanliness levels, test methods, cleaning and packaging requirements, and protection and inspection procedures for determining surface cleanliness. These surfaces pertain to aerospace parts, components, assemblies, subsystems, and systems in contact with any fluid medium.

  10. Use of mucolytics to enhance magnetic particle retention at a model airway surface

    NASA Astrophysics Data System (ADS)

    Ally, Javed; Roa, Wilson; Amirfazli, A.

    A previous study has shown that retention of magnetic particles at a model airway surface requires prohibitively strong magnetic fields. As mucus viscoelasticity is the most significant factor contributing to clearance of magnetic particles from the airway surface, mucolytics are considered in this study to reduce mucus viscoelasticity and enable particle retention with moderate strength magnetic fields. The excised frog palate model was used to simulate the airway surface. Two mucolytics, N-acetylcysteine (NAC) and dextran sulfate (DS) were tested. NAC was found to enable retention at moderate field values (148 mT with a gradient of 10.2 T/m), whereas DS was found to be effective only for sufficiently large particle concentrations at the airway surface. The possible mechanisms for the observed behavior with different mucolytics are also discussed based on aggregate formation and the loading of cilia.

  11. Contribution of rostral fluid shift to intrathoracic airway narrowing in asthma.

    PubMed

    Bhatawadekar, Swati A; Inman, Mark D; Fredberg, Jeffrey J; Tarlo, Susan M; Lyons, Owen D; Keller, Gabriel; Yadollahi, Azadeh

    2017-04-01

    In asthma, supine posture and sleep increase intrathoracic airway narrowing. When humans are supine, because of gravity fluid moves out of the legs and accumulates in the thorax. We hypothesized that fluid shifting out of the legs into the thorax contributes to the intrathoracic airway narrowing in asthma. Healthy and asthmatic subjects sat for 30 min and then lay supine for 30 min. To simulate overnight fluid shift, supine subjects were randomized to receive increased fluid shift out of the legs with lower body positive pressure (LBPP, 10-30 min) or none (control) and crossed over. With forced oscillation at 5 Hz, respiratory resistance (R5) and reactance (X5, reflecting respiratory stiffness) and with bioelectrical impedance, leg and thoracic fluid volumes (LFV, TFV) were measured while subjects were seated and supine (0 min, 30 min). In 17 healthy subjects (age: 51.8 ± 10.9 yr, FEV1/FVC z score: -0.4 ± 1.1), changes in R5 and X5 were similar in both study arms (P > 0.05). In 15 asthmatic subjects (58.5 ± 9.8 yr, -2.1 ± 1.3), R5 and X5 increased in both arms (ΔR5: 0.6 ± 0.9 vs. 1.4 ± 0.8 cmH2O·l(-1)·s(-1), ΔX5: 0.3 ± 0.7 vs. 1.1 ± 0.9 cmH2O·l(-1)·s(-1)). The increases in R5 and X5 were 2.3 and 3.7 times larger with LBPP than control, however (P = 0.008, P = 0.006). The main predictor of increases in R5 with LBPP was increases in TFV (r = 0.73, P = 0.002). In asthmatic subjects, the magnitude of increases in X5 with LBPP was comparable to that with posture change from sitting to supine (1.1 ± 0.9 vs. 1.4 ± 0.9 cmH2O·l(-1)·s(-1), P = 0.32). We conclude that in asthmatic subjects fluid shifting from the legs to the thorax while supine contributed to increases in the respiratory resistance and stiffness.NEW & NOTEWORTHY In supine asthmatic subjects, application of positive pressure to the lower body caused appreciable increases in respiratory system resistance and stiffness. Moreover, these changes in respiratory mechanics correlated positively with

  12. Surface modeling and segmentation of the 3D airway wall in MSCT

    NASA Astrophysics Data System (ADS)

    Ortner, Margarete; Fetita, Catalin; Brillet, Pierre-Yves; Pr"teux, Françoise; Grenier, Philippe

    2011-03-01

    Airway wall remodeling in asthma and chronic obstructive pulmonary disease (COPD) is a well-known indicator of the pathology. In this context, current clinical studies aim for establishing the relationship between the airway morphological structure and its function. Multislice computed tomography (MSCT) allows morphometric assessment of airways, but requires dedicated segmentation tools for clinical exploitation. While most of the existing tools are limited to cross-section measurements, this paper develops a fully 3D approach for airway wall segmentation. Such approach relies on a deformable model which is built up as a patient-specific surface model at the level of the airway lumen and deformed to reach the outer surface of the airway wall. The deformation dynamics obey a force equilibrium in a Lagrangian framework constrained by a vector field which avoids model self-intersections. The segmentation result allows a dense quantitative investigation of the airway wall thickness with a deeper insight at bronchus subdivisions than classic cross-section methods. The developed approach has been assessed both by visual inspection of 2D cross-sections, performed by two experienced radiologists on clinical data obtained with various protocols, and by using a simulated ground truth (pulmonary CT image model). The results confirmed a robust segmentation in intra-pulmonary regions with an error in the range of the MSCT image resolution and underlined the interest of the volumetric approach versus purely 2D methods.

  13. The osmolyte xylitol reduces the salt concentration of airway surface liquid and may enhance bacterial killing

    NASA Astrophysics Data System (ADS)

    Zabner, Joseph; Seiler, Michael P.; Launspach, Janice L.; Karp, Philip H.; Kearney, William R.; Look, Dwight C.; Smith, Jeffrey J.; Welsh, Michael J.

    2000-10-01

    The thin layer of airway surface liquid (ASL) contains antimicrobial substances that kill the small numbers of bacteria that are constantly being deposited in the lungs. An increase in ASL salt concentration inhibits the activity of airway antimicrobial factors and may partially explain the pathogenesis of cystic fibrosis (CF). We tested the hypothesis that an osmolyte with a low transepithelial permeability may lower the ASL salt concentration, thereby enhancing innate immunity. We found that the five-carbon sugar xylitol has a low transepithelial permeability, is poorly metabolized by several bacteria, and can lower the ASL salt concentration in both CF and non-CF airway epithelia in vitro. Furthermore, in a double-blind, randomized, crossover study, xylitol sprayed for 4 days into each nostril of normal volunteers significantly decreased the number of nasal coagulase-negative Staphylococcus compared with saline control. Xylitol may be of value in decreasing ASL salt concentration and enhancing the innate antimicrobial defense at the airway surface.

  14. Airway surface liquid depth measured in ex vivo fragments of pig and human trachea: dependence on Na+ and Cl− channel function

    PubMed Central

    Song, Yuanlin; Namkung, Wan; Nielson, Dennis W.; Lee, Jae-Woo; Finkbeiner, Walter E.

    2009-01-01

    The airway surface liquid (ASL) is the thin fluid layer lining the airways whose depth may be reduced in cystic fibrosis. Prior measurements of ASL depth have been made in airway epithelial cell cultures. Here, we established methodology to measure ASL depth to ∼1-μm accuracy in ex vivo fragments of freshly obtained human and pig tracheas. Airway fragments were mounted in chambers designed for perfusion of the basal surface and observation of the apical, fluorescently stained ASL by scanning confocal microscopy using a high numerical aperture lens immersed in perfluorocarbon. Measurement accuracy was verified using standards of specified fluid thickness. ASL depth in well-differentiated primary cultures of human nasal respiratory epithelium was 8.0 ± 0.5 μm (SE 10 cultures) under basal conditions, 8.4 ± 0.4 μm following ENaC inhibition by amiloride, and 14.5 ± 1.2 μm following CFTR stimulation by cAMP agonists. ASL depth in human trachea was 7.0 ± 0.7 μm under basal conditions, 11.0 ± 1.7 μm following amiloride, 17.0 ± 3.4 μm following cAMP agonists, and 7.1 ± 0.5 μm after CFTR inhibition. Similar results were found in pig trachea. This study provides the first direct measurements of ASL depth in intact human airways and indicates the involvement of ENaC sodium channels and CFTR chloride channels in determining ASL depth. We suggest that CF lung disease may be caused by the inability of CFTR-deficient airways to increase their ASL depth transiently following secretory stimuli that in non-CF airways produce transient increases in ASL depth. PMID:19820035

  15. Computational fluid dynamics for the assessment of upper airway response to oral appliance treatment in obstructive sleep apnea.

    PubMed

    Zhao, Moyin; Barber, Tracie; Cistulli, Peter; Sutherland, Kate; Rosengarten, Gary

    2013-01-04

    Mandibular advancement splints (MAS), which protrude the lower jaw during sleep, are recognized as an effective treatment for obstructive sleep apnea (OSA) through their action of enlarging the airway space and preventing upper airway collapse. However a clinical challenge remains in preselecting patients who will respond to this form of therapy. We aimed to use computational fluid dynamics (CFD) in conjunction with patient upper airway scans to understand the upper airway response to treatment. Seven OSA patients were selected based on their varied treatment response (assessed by the apnea-hypopnoea index (AHI) on overnight polysomnography). Anatomically-accurate upper airway computational models were reconstructed from magnetic resonance images with and without MAS. CFD simulations of airflow were performed at the maximum flow rate during inspiration. A physical airway model of one patient was fabricated and the CFD method was validated against the pressure profile on the physical model. The CFD analysis clearly demonstrated effects of MAS treatment on the patient's UA airflow patterns. The CFD results indicated the lowest pressure often occurs close to the soft palate and the base of the tongue. Percentage change in the square root of airway pressure gradient with MAS (Δsqrt(ΔP(Max))%) was found to have the strongest relationship with treatment response (ΔAHI%) in correlation analysis (r=0.976, p=0.000167). Changes in upper airway geometry alone did not significantly correlate with treatment response. We provide further support of CFD as a potential tool for prediction of treatment outcome with MAS in OSA patients without requiring patient specific flow rates.

  16. A Spatial Model of Fluid Recycling in the Airways of the Lung

    PubMed Central

    Sharp, K.; Crampin, E.; Sneyd, J.

    2015-01-01

    The genetic disease cystic fibrosis (CF) is a mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, and results in viscous mucus and impaired mucociliary clearance leading to chronic recurring pulmonary infections. Although extensive experimental research has been conducted over the last few decades, CF lung pathophysiology remains controversial. There are two competing explanations for the observed depletion of periciliary liquid (PCL) in CF lungs. The low volume hypothesis assumes fluid hyperabsorption through surface epithelia due to an over-active Epithelial Na+ Channel (ENaC), and the low secretion hypothesis assumes inspissated mucins secreted from glands due to lack of serous fluid secreted from gland acini. We present a spatial mathematical model that reflects in vivo fluid recycling via submucosal gland (SMG) secretion, and absorption through surface epithelia. We then test the model in CF conditions by increasing ENaC open probability and decreasing SMG flux while simultaneously reducing CFTR open probability. Increasing ENaC activity only results in increased fluid absorption across surface epithelia, as seen in in vitro experiments. However, combining potential CF mechanisms results in markedly less fluid absorbed while providing the largest reduction in PCL volume, suggesting that a compromise in gland fluid secretion dominates over increased ENaC activity to decrease the amount of fluid transported transcellularly in CF lungs in vivo. Model results also indicate that a spatial model is necessary for an accurate calculation of total fluid transport, as the effects of spatial gradients can be severe, particularly in close proximity to the SMGs. PMID:26169010

  17. Analysis of Fluid Flow over a Surface

    NASA Technical Reports Server (NTRS)

    McCloud, Peter L. (Inventor)

    2013-01-01

    A method, apparatus, and computer program product for modeling heat radiated by a structure. The flow of a fluid over a surface of a model of the structure is simulated. The surface has a plurality of surface elements. Heat radiated by the plurality of surface elements in response to the fluid flowing over the surface of the model of the structure is identified. An effect of heat radiated by at least a portion of the plurality of surface elements on each other is identified. A model of the heat radiated by the structure is created using the heat radiated by the plurality of surface elements and the effect of the heat radiated by at least a portion of the plurality of surface elements on each other.

  18. High resolution lung airway cast segmentation with proper topology suitable for computational fluid dynamic simulations.

    PubMed

    Carson, James P; Einstein, Daniel R; Minard, Kevin R; Fanucchi, Michelle V; Wallis, Christopher D; Corley, Richard A

    2010-10-01

    Developing detailed lung airway models is an important step towards understanding the respiratory system. While modern imaging and airway casting approaches have dramatically improved the potential detail of such models, challenges have arisen in image processing as the demand for greater detail pushes the image processing approaches to their limits. Airway segmentations with proper topology have neither loops nor invalid voxel-to-voxel connections. Here we describe a new technique for segmenting airways with proper topology and apply the approach to an image volume generated by magnetic resonance imaging of a silicone cast created from an excised monkey lung.

  19. A model for the volume regulatory mechanism of the Airway Surface Layer

    NASA Astrophysics Data System (ADS)

    Lang, Michael; Rubinstein, Michael; Davis, C. William; Tarran, Robert; Boucher, Richard

    2006-03-01

    The airway surface layer (ASL) of a lung consists of two parts: a mucus layer with thickness of about 30 μm in contact with air and a periciliary layer (PCL) of about 7 μm below. Mucus collects dust and bacteria and is swept to throat by beating cilia, while riding on top of PCL. It is important that the thickness of PCL is matched with the length of cilia in order to optimize clearance of mucus. Decrease of PCL thickness would finally lead to an occlusion of the respiratory system. Experiments show that the height of PCL stays constant after removing mucus. When modifying height or composition of this open PCL by removing fluid or adding isotonic solution leads to the same final height of PCL. Thus, there must be a regulatory mechanism, that controls height, i.e. ASL volume. Additional experiments show that mechanical stimulus of the cells like shear leads to an increase of ASL volume, thus, the cell is able to actively adjust this volume. Based on these observations a class of models is introduced that describes the experiments and a specific minimum model for the given problem is proposed.

  20. Fluid-Structure Analysis of Opening Phenomena in a Collapsible Airway

    NASA Astrophysics Data System (ADS)

    Ghadiali, Samir N.; Banks, Julie; Swarts, J. Douglas

    2003-11-01

    Several physiological functions require the opening of collapsed respiratory airways. For example, the Eustachian tube (ET), which connects the nasopharynx with the middle ear (ME), must be periodically opened to maintain ambient ME pressures. These openings normally occur during swallowing when muscle contraction deforms the surrounding soft tissue. The inability to open the ET results in the most common and costly ear disease in children, Otitis Media. Although tissue-based treatments have been purposed, the influence of the various tissue mechanical properties on flow phenomena has not been investigated. A computational model of ET opening was developed using in-vivo structural data to investigate these fluid-structure interactions. This model accounts for both tissue deformation and the resulting airflow in a non-circular conduit. Results indicate that ET opening is more sensitive to the applied muscle forces than elastic tissue properties. These models have therefore identified how different tissue elements alter ET opening phenomena, which elements should be targeted for treatment and the optimal mechanical properties of these tissue constructs. Research supported by NIH grant DC005345.

  1. Computer simulation of fluid flow and particle diffusion within human upper airways system

    NASA Astrophysics Data System (ADS)

    Yu, Genqiang

    Computer simulation of air flow and particle transport phenomenon within the human upper respiratory system has important applications in inhalation toxicology, aerosol medicine delivery as well as basic medical science research. A three-dimensional physiologically realistic computer model of the human upper respiratory tract has been developed. The respiratory tract consists of nasal airways, oral airways, laryngeal airways and the first two generations of tracheobronchial airways. A rubber mold of the airway system was first cast from the impression of the human head airway teaching model. The rubber cast was sliced into 2mm-apart parallel pieces. The cross-sectional geometry of the sliced rubber pieces were then scanned into the computer to be stored as the digital information. A body-fitted three-dimensional curvilinear grid system and a multi-block method have been employed to mimic the complex head airway. A total of 280,000 grid node was used for the entire respiratory tract. Air flow patterns within the human upper airways are investigated by numerically solving the corresponding full Navier-Stokes equations using the flow simulation software CFX-F3D. Effects of human breath patterns on respiratory flow distribution and ultrafine particle deposition are investigated. Results of ultrafine particle deposition generated by computer simulation show reasonable agreements with the experimental measurements.

  2. Dropwise Condensation of Low Surface Tension Fluids on Omniphobic Surfaces

    PubMed Central

    Rykaczewski, Konrad; Paxson, Adam T.; Staymates, Matthew; Walker, Marlon L.; Sun, Xiaoda; Anand, Sushant; Srinivasan, Siddarth; McKinley, Gareth H.; Chinn, Jeff; Scott, John Henry J.; Varanasi, Kripa K.

    2014-01-01

    Compared to the significant body of work devoted to surface engineering for promoting dropwise condensation heat transfer of steam, much less attention has been dedicated to fluids with lower interfacial tension. A vast array of low-surface tension fluids such as hydrocarbons, cryogens, and fluorinated refrigerants are used in a number of industrial applications, and the development of passive means for increasing their condensation heat transfer coefficients has potential for significant efficiency enhancements. Here we investigate condensation behavior of a variety of liquids with surface tensions in the range of 12 to 28 mN/m on three types of omniphobic surfaces: smooth oleophobic, re-entrant superomniphobic, and lubricant-impregnated surfaces. We demonstrate that although smooth oleophobic and lubricant-impregnated surfaces can promote dropwise condensation of the majority of these fluids, re-entrant omniphobic surfaces became flooded and reverted to filmwise condensation. We also demonstrate that on the lubricant-impregnated surfaces, the choice of lubricant and underlying surface texture play a crucial role in stabilizing the lubricant and reducing pinning of the condensate. With properly engineered surfaces to promote dropwise condensation of low-surface tension fluids, we demonstrate a four to eight-fold improvement in the heat transfer coefficient. PMID:24595171

  3. Dropwise condensation of low surface tension fluids on omniphobic surfaces.

    PubMed

    Rykaczewski, Konrad; Paxson, Adam T; Staymates, Matthew; Walker, Marlon L; Sun, Xiaoda; Anand, Sushant; Srinivasan, Siddarth; McKinley, Gareth H; Chinn, Jeff; Scott, John Henry J; Varanasi, Kripa K

    2014-03-05

    Compared to the significant body of work devoted to surface engineering for promoting dropwise condensation heat transfer of steam, much less attention has been dedicated to fluids with lower interfacial tension. A vast array of low-surface tension fluids such as hydrocarbons, cryogens, and fluorinated refrigerants are used in a number of industrial applications, and the development of passive means for increasing their condensation heat transfer coefficients has potential for significant efficiency enhancements. Here we investigate condensation behavior of a variety of liquids with surface tensions in the range of 12 to 28 mN/m on three types of omniphobic surfaces: smooth oleophobic, re-entrant superomniphobic, and lubricant-impregnated surfaces. We demonstrate that although smooth oleophobic and lubricant-impregnated surfaces can promote dropwise condensation of the majority of these fluids, re-entrant omniphobic surfaces became flooded and reverted to filmwise condensation. We also demonstrate that on the lubricant-impregnated surfaces, the choice of lubricant and underlying surface texture play a crucial role in stabilizing the lubricant and reducing pinning of the condensate. With properly engineered surfaces to promote dropwise condensation of low-surface tension fluids, we demonstrate a four to eight-fold improvement in the heat transfer coefficient.

  4. Airway surface liquid volume expansion induces rapid changes in amiloride-sensitive Na+ transport across upper airway epithelium-Implications concerning the resolution of pulmonary edema

    PubMed Central

    Azizi, Fouad; Arredouani, Abdelilah; Mohammad, Ramzi M

    2015-01-01

    During airway inflammation, airway surface liquid volume (ASLV) expansion may result from the movement of plasma proteins and excess liquid into the airway lumen due to extravasation and elevation of subepithelial hydrostatic pressure. We previously demonstrated that elevation of submucosal hydrostatic pressure increases airway epithelium permeability resulting in ASLV expansion by 500 μL cm−2 h−1. Liquid reabsorption by healthy airway epithelium is regulated by active Na+ transport at a rate of 5 μL cm−2 h−1. Thus, during inflammation the airway epithelium may be submerged by a large volume of luminal liquid. Here, we have investigated the mechanism by which ASLV expansion alters active epithelial Na+ transport, and we have characterized the time course of the change. We used primary cultures of tracheal airway epithelium maintained under air interface (basal ASLV, depth is 7 ± 0.5 μm). To mimic airway flooding, ASLV was expanded to a depth of 5 mm. On switching from basal to expanded ASLV conditions, short-circuit current (Isc, a measure of total transepithelial active ion transport) declined by 90% with a half-time (t1/2) of 1 h. 24 h after the switch, there was no significant change in ATP concentration nor in the number of functional sodium pumps as revealed by [3H]-ouabain binding. However, amiloride-sensitive uptake of 22Na+ was reduced by 70% upon ASLV expansion. This process is reversible since after returning cells back to air interface, Isc recovered with a t1/2 of 5–10 h. These results may have important clinical implications concerning the development of Na+ channels activators and resolution of pulmonary edema. PMID:26333829

  5. Role of Mechanical Stress in Regulating Airway Surface Hydration and Mucus Clearance Rates

    PubMed Central

    Button, Brian; Boucher, Richard C.

    2008-01-01

    Effective clearance of mucus is a critical innate airway defense mechanism, and under appropriate conditions, can be stimulated to enhance clearance of inhaled pathogens. It has become increasingly clear that extracellular nucleotides (ATP and UTP) and nucleosides (adenosine) are important regulators of mucus clearance in the airways as a result of their ability to stimulate fluid secretion, mucus hydration, and cilia beat frequency (CBF). One ubiquitous mechanism to stimulate ATP release is through external mechanical stress. This article addresses the role of physiologically-relevant mechanical forces in the lung and their effects on regulating mucociliary clearance (MCC). The effects of mechanical forces on the stimulating ATP release, fluid secretion, CBF, and MCC are discussed. Also discussed is evidence suggesting that airway hydration and stimulation of MCC by stress-mediated ATP release may play a role in several therapeutic strategies directed at improving mucus clearance in patients with obstructive lung diseases, including cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD). PMID:18585484

  6. In Vivo Airway Surface Liquid Cl− Analysis with Solid-State Electrodes

    PubMed Central

    Caldwell, Ray A.; Grubb, Barbara R.; Tarran, Robert; Boucher, Richard C.; Knowles, Michael R.; Barker, Pierre M.

    2002-01-01

    The pathogenesis of cystic fibrosis (CF) airways disease remains controversial. Hypotheses that link mutations in CFTR and defects in ion transport to CF lung disease predict that alterations in airway surface liquid (ASL) isotonic volume, or ion composition, are critically important. ASL [Cl−] is pivotal in discriminating between these hypotheses, but there is no consensus on this value given the difficulty in measuring [Cl−] in the “thin” ASL (∼30 μm) in vivo. Consequently, a miniaturized solid-state electrode with a shallow depth of immersion was constructed to measure ASL [Cl−] in vivo. In initial experiments, the electrode measured [Cl−] in physiologic salt solutions, small volume (7.6 μl) test solutions, and in in vitro cell culture models, with ≥93% accuracy. Based on discrepancies in reported values and/or absence of data, ASL Cl− measurements were made in the following airway regions and species. First, ASL [Cl−] was measured in normal human nasal cavity and averaged 117.3 ± 11.2 mM (n = 6). Second, ASL [Cl−] measured in large airway (tracheobronchial) regions were as follows: rabbit trachea and bronchus = 114.3 ± 1.8 mM; (n = 6) and 126.9 ± 1.7 mM; (n = 3), respectively; mouse trachea = 112.8 ± 4.2 mM (n = 13); and monkey bronchus = 112.3 ± 10.9 mM (n = 3). Third, Cl− measurements were made in small (1–2 mm) diameter airways of the rabbit (108.3 ± 7.1 mM, n = 5) and monkey (128.5 ± 6.8 mM, n = 3). The measured [Cl−], in excess of 100 mM throughout all airway regions tested in multiple species, is consistent with the isotonic volume hypothesis to describe ASL physiology. PMID:11773234

  7. Airway surface liquid homeostasis in cystic fibrosis: pathophysiology and therapeutic targets.

    PubMed

    Haq, Iram J; Gray, Michael A; Garnett, James P; Ward, Christopher; Brodlie, Malcolm

    2016-03-01

    Cystic fibrosis (CF) is a life-limiting disease characterised by recurrent respiratory infections, inflammation and lung damage. The volume and composition of the airway surface liquid (ASL) are important in maintaining ciliary function, mucociliary clearance and antimicrobial properties of the airway. In CF, these homeostatic mechanisms are impaired, leading to a dehydrated and acidic ASL. ASL volume depletion in CF is secondary to defective anion transport by the abnormal cystic fibrosis transmembrane conductance regulator protein (CFTR). Abnormal CFTR mediated bicarbonate transport creates an unfavourable, acidic environment, which impairs antimicrobial function and alters mucus properties and clearance. These disease mechanisms create a disordered airway milieu, consisting of thick mucopurulent secretions and chronic bacterial infection. In addition to CFTR, there are additional ion channels and transporters in the apical airway epithelium that play a role in maintaining ASL homeostasis. These include the epithelial sodium channel (ENaC), the solute carrier 26A (SLC26A) family of anion exchangers, and calcium-activated chloride channels. In this review we discuss how the ASL is abnormal in CF and how targeting these alternative channels and transporters could provide an attractive therapeutic strategy to correct the underlying ASL abnormalities evident in CF.

  8. Effect of Nasal Obstruction on Continuous Positive Airway Pressure Treatment: Computational Fluid Dynamics Analyses

    PubMed Central

    Wakayama, Tadashi; Suzuki, Masaaki; Tanuma, Tadashi

    2016-01-01

    Objective Nasal obstruction is a common problem in continuous positive airway pressure (CPAP) therapy for obstructive sleep apnea and limits treatment compliance. The purpose of this study is to model the effects of nasal obstruction on airflow parameters under CPAP using computational fluid dynamics (CFD), and to clarify quantitatively the relation between airflow velocity and pressure loss coefficient in subjects with and without nasal obstruction. Methods We conducted an observational cross-sectional study of 16 Japanese adult subjects, of whom 9 had nasal obstruction and 7 did not (control group). Three-dimensional reconstructed models of the nasal cavity and nasopharynx with a CPAP mask fitted to the nostrils were created from each subject’s CT scans. The digital models were meshed with tetrahedral cells and stereolithography formats were created. CPAP airflow simulations were conducted using CFD software. Airflow streamlines and velocity contours in the nasal cavities and nasopharynx were compared between groups. Simulation models were confirmed to agree with actual measurements of nasal flow rate and with pressure and flow rate in the CPAP machine. Results Under 10 cmH2O CPAP, average maximum airflow velocity during inspiration was 17.6 ± 5.6 m/s in the nasal obstruction group but only 11.8 ± 1.4 m/s in the control group. The average pressure drop in the nasopharynx relative to inlet static pressure was 2.44 ± 1.41 cmH2O in the nasal obstruction group but only 1.17 ± 0.29 cmH2O in the control group. The nasal obstruction and control groups were clearly separated by a velocity threshold of 13.5 m/s, and pressure loss coefficient threshold of approximately 10.0. In contrast, there was no significant difference in expiratory pressure in the nasopharynx between the groups. Conclusion This is the first CFD analysis of the effect of nasal obstruction on CPAP treatment. A strong correlation between the inspiratory pressure loss coefficient and maximum airflow

  9. Simulation of upper airway occlusion without and with mandibular advancement in obstructive sleep apnea using fluid-structure interaction.

    PubMed

    Zhao, Moyin; Barber, Tracie; Cistulli, Peter A; Sutherland, Kate; Rosengarten, Gary

    2013-10-18

    Obstructive Sleep Apnea (OSA) is a common sleep disorder characterized by repetitive collapse of the upper airway (UA). One treatment option is a mandibular advancement splint (MAS) which protrudes the lower jaw, stabilizing the airway. However not all patients respond to MAS therapy and individual effects are not well understood. Simulations of airway behavior may represent a non-invasive means to understand OSA and individual treatment responses. Our aims were (1) to analyze UA occlusion and flow dynamics in OSA using the fluid structure interaction (FSI) method, and (2) to observe changes with MAS. Magnetic resonance imaging (MRI) scans were obtained at baseline and with MAS in a known treatment responder. Computational models of the patients' UA geometry were reconstructed for both conditions. The FSI model demonstrated full collapse of the UA (maximum 5.83mm) pre-treatment (without MAS). The UA collapse was located at the oropharynx with low oropharyngeal pressure (-51.18Pa to -39.08Pa) induced by velopharyngeal jet flow (maximum 10.0m/s). By comparison, simulation results from the UA with MAS, showed smaller deformation (maximum 2.03mm), matching the known clinical response. Our FSI modeling method was validated by physical experiment on a 1:1 flexible UA model fabricated using 3D steriolithography. This is the first study of airflow dynamics in a deformable UA structure and inspiratory flow. These results expand on previous UA models using computational fluid dynamics (CFD), and lay a platform for application of computational models to study biomechanical properties of the UA in the pathogenesis and treatment of OSA.

  10. Numerical and experimental study of expiratory flow in the case of major upper airway obstructions with fluid structure interaction

    NASA Astrophysics Data System (ADS)

    Chouly, F.; van Hirtum, A.; Lagrée, P.-Y.; Pelorson, X.; Payan, Y.

    2008-02-01

    This study deals with the numerical prediction and experimental description of the flow-induced deformation in a rapidly convergent divergent geometry which stands for a simplified tongue, in interaction with an expiratory airflow. An original in vitro experimental model is proposed, which allows measurement of the deformation of the artificial tongue, in condition of major initial airway obstruction. The experimental model accounts for asymmetries in geometry and tissue properties which are two major physiological upper airway characteristics. The numerical method for prediction of the fluid structure interaction is described. The theory of linear elasticity in small deformations has been chosen to compute the mechanical behaviour of the tongue. The main features of the flow are taken into account using a boundary layer theory. The overall numerical method entails finite element solving of the solid problem and finite differences solving of the fluid problem. First, the numerical method predicts the deformation of the tongue with an overall error of the order of 20%, which can be seen as a preliminary successful validation of the theory and simulations. Moreover, expiratory flow limitation is predicted in this configuration. As a result, both the physical and numerical models could be useful to understand this phenomenon reported in heavy snorers and apneic patients during sleep.

  11. Increased phosphatidylcholine concentration in saliva reduces surface tension and improves airway patency in obstructive sleep apnoea.

    PubMed

    Kawai, M; Kirkness, J P; Yamamura, S; Imaizumi, K; Yoshimine, H; Oi, K; Ayuse, T

    2013-10-01

    Surface tension may have important role for maintaining upper airway patency in patients with obstructive sleep apnoea. It has been demonstrated that elevated surface tension increases the pharyngeal pressures required to reopen the upper airway following collapse. The aim of the study was to evaluate the associations between the concentrations of endogenous surfactants in saliva with indices of upper airway patency in obstructive sleep apnoea. We studied 20 male patients with obstructive sleep apnoea (age: 60·3 ± 10·3 years; BMI: 25·9 ± 4·6 kg m(-2); AHI: 41·5 ± 18·6 events h(-1)). We obtained 100-μL samples of saliva prior to overnight polysomnographic sleep study. The surface tension was determined using the pull-off force technique. The concentration of phosphatidylcholine (PC) was evaluated by liquid chromatography-mass spectrometry (LC-MS/MS). Regression analysis between apnoea, hypopnoea and apnoea/hypopnoea indices and the ratio of hypopnoea time/total disordered breathing time (HT/DBT) with surface tension and PC were performed. P < 0·05 was considered significant. The mean saliva surface tension was 48·8 ± 8·0 mN m(-1) and PC concentration was 15·7 ± 11·1 nM. The surface tension was negatively correlated with the PC concentration (r = -0·48, P = 0·03). There was a significant positive correlation between surface tension with hypopnoea index (r = 0·50, P = 0·03) and HT/DBT (r = 0·6, P = 0·006), but not apnoea or apnoea/hypopnoea index (P > 0·11). Similarly, PC concentration negatively correlated with hypopnoea index (r = -0·45, P = 0·04) and HT/DBT (r = -0·6, P = 0·004), but not with apnoea index or AHI (P > 0·08). An increase in salivary PC concentration may increase upper airway patency in obstructive sleep apnoea through a reduction in surface tension.

  12. LES of Laminar-to-Turbulent Particle-Fluid Dynamics in Human and Nonhuman Primate Airways: Applications to Aerosolized Drug Delivery Animal Testing

    NASA Astrophysics Data System (ADS)

    Geisler, Taylor; Padhy, Sourav; Shaqfeh, Eric; Iaccarino, Gianluca

    2016-11-01

    Both the human health benefit and risk from the inhalation of aerosolized medications is often predicted by extrapolating experimental data taken using nonhuman primates to human inhalation. In this study, we employ Large Eddy Simulation to simulate particle-fluid dynamics in realistic upper airway models of both humans and rhesus monkeys. We report laminar-to-turbulent flow transitions triggered by constrictions in the upper trachea and the persistence of unsteadiness into the low Reynolds number bifurcating lower airway. Micro-particle deposition fraction and locations are shown to depend significantly on particle size. In particular, particle filtration in the nasal airways is shown to approach unity for large aerosols (8 microns) or high-rate breathing. We validate the accuracy of LES mean flow predictions using MRV imaging results. Additionally, particle deposition fractions are validated against experiments in 3 model airways.

  13. Pseudomonas aeruginosa triggers CFTR-mediated airway surface liquid secretion in swine trachea.

    PubMed

    Luan, Xiaojie; Campanucci, Verónica A; Nair, Manoj; Yilmaz, Orhan; Belev, George; Machen, Terry E; Chapman, Dean; Ianowski, Juan P

    2014-09-02

    Cystic fibrosis (CF) is an autosomal recessive genetic disorder caused by mutations in the gene encoding for the anion channel cystic fibrosis transmembrane conductance regulator (CFTR). Several organs are affected in CF, but most of the morbidity and mortality comes from lung disease. Recent data show that the initial consequence of CFTR mutation is the failure to eradicate bacteria before the development of inflammation and airway remodeling. Bacterial clearance depends on a layer of airway surface liquid (ASL) consisting of both a mucus layer that traps, kills, and inactivates bacteria and a periciliary liquid layer that keeps the mucus at an optimum distance from the underlying epithelia, to maximize ciliary motility and clearance of bacteria. The airways in CF patients and animal models of CF demonstrate abnormal ASL secretion and reduced antimicrobial properties. Thus, it has been proposed that abnormal ASL secretion in response to bacteria may facilitate the development of the infection and inflammation that characterize CF airway disease. Whether the inhalation of bacteria triggers ASL secretion, and the role of CFTR, have never been tested, however. We developed a synchrotron-based imaging technique to visualize the ASL layer and measure the effect of bacteria on ASL secretion. We show that the introduction of Pseudomonas aeruginosa and other bacteria into the lumen of intact isolated swine tracheas triggers CFTR-dependent ASL secretion by the submucosal glands. This response requires expression of the bacterial protein flagellin. In patients with CF, the inhalation of bacteria would fail to trigger ASL secretion, leading to infection and inflammation.

  14. Non-Genomic Estrogen Regulation of Ion Transport and Airway Surface Liquid Dynamics in Cystic Fibrosis Bronchial Epithelium

    PubMed Central

    Saint-Criq, Vinciane; Kim, Sung Hoon; Katzenellenbogen, John A.; Harvey, Brian J.

    2013-01-01

    Male cystic fibrosis (CF) patients survive longer than females and lung exacerbations in CF females vary during the estrous cycle. Estrogen has been reported to reduce the height of the airway surface liquid (ASL) in female CF bronchial epithelium. Here we investigated the effect of 17β-estradiol on the airway surface liquid height and ion transport in normal (NuLi-1) and CF (CuFi-1) bronchial epithelial monolayers. Live cell imaging using confocal microscopy revealed that airway surface liquid height was significantly higher in the non-CF cells compared to the CF cells. 17β-estradiol (0.1–10 nM) reduced the airway surface liquid height in non-CF and CF cells after 30 min treatment. Treatment with the nuclear-impeded Estrogen Dendrimer Conjugate mimicked the effect of free estrogen by reducing significantly the airway surface liquid height in CF and non-CF cells. Inhibition of chloride transport or basolateral potassium recycling decreased the airway surface liquid height and 17β-estradiol had no additive effect in the presence of these ion transporter inhibitors. 17β-estradiol decreased bumetanide-sensitive transepithelial short-circuit current in non-CF cells and prevented the forskolin-induced increase in ASL height. 17β-estradiol stimulated an amiloride-sensitive transepithelial current and increased ouabain-sensitive basolateral short-circuit current in CF cells. 17β-estradiol increased PKCδ activity in CF and non-CF cells. These results demonstrate that estrogen dehydrates CF and non-CF ASL, and these responses to 17β-estradiol are non-genomic rather than involving the classical nuclear estrogen receptor pathway. 17β-estradiol acts on the airway surface liquid by inhibiting cAMP-mediated chloride secretion in non-CF cells and increasing sodium absorption via the stimulation of PKCδ, ENaC and the Na+/K+ATPase in CF cells. PMID:24223826

  15. Computational fluid dynamics simulation of the upper airway response to large incisor retraction in adult class I bimaxillary protrusion patients

    PubMed Central

    Zheng, Zhe; Liu, Hong; Xu, Qi; Wu, Wei; Du, Liling; Chen, Hong; Zhang, Yiwen; Liu, Dongxu

    2017-01-01

    The changes of the upper airway after large retraction of the incisors in adult class I bimaxillary protrusion patients were assessed mainly focused on the anatomic variation and ignored the functional changes. This study aimed to investigate the changes of the upper airway in adult class I bimaxillary protrusion patients after extraction treatment using the functional images based on computational fluid dynamics (CFD). CFD was implemented after 3D reconstruction based on the CBCT of 30 patients who have completed extraction treatment. After treatment, pressure drop in the minimum area, oropharynx, and hypopharynx increased significantly. The minimum pressure and the maximum velocity mainly located in the hypopharynx in pre-treatment while they mostly occured in the oropharynx after treatment. Statistically significant correlation between pressure drop and anatomic parameters, pressure drop and treatment outcomes was found. No statistical significance changes in pressure drop and volume of nasopharynx was found. This study suggested that the risk of pharyngeal collapsing become higher after extraction treatment with maximum anchorage in bimaxillary protrusion adult patients. Those adverse changes should be taken into consideration especially for high-risk patients to avoid undesired weakening of the respiratory function in clinical treatment. PMID:28387372

  16. Bicarbonate-dependent chloride transport drives fluid secretion by the human airway epithelial cell line Calu-3

    PubMed Central

    Shan, Jiajie; Liao, Jie; Huang, Junwei; Robert, Renaud; Palmer, Melissa L; Fahrenkrug, Scott C; O'Grady, Scott M; Hanrahan, John W

    2012-01-01

    Anion and fluid secretion are both defective in cystic fibrosis (CF); however, the transport mechanisms are not well understood. In this study, Cl− and HCO3− secretion was measured using genetically matched CF transmembrane conductance regulator (CFTR)-deficient and CFTR-expressing cell lines derived from the human airway epithelial cell line Calu-3. Forskolin stimulated the short-circuit current (Isc) across voltage-clamped monolayers, and also increased the equivalent short-circuit current (Ieq) calculated under open-circuit conditions. Isc was equivalent to the HCO3− net flux measured using the pH-stat technique, whereas Ieq was the sum of the Cl− and HCO3− net fluxes. Ieq and HCO3− fluxes were increased by bafilomycin and ZnCl2, suggesting that some secreted HCO3− is neutralized by parallel electrogenic H+ secretion. Ieq and fluid secretion were dependent on the presence of both Na+ and HCO3−. The carbonic anhydrase inhibitor acetazolamide abolished forskolin stimulation of Ieq and HCO3− secretion, suggesting that HCO3− transport under these conditions requires catalysed synthesis of carbonic acid. Cl− was the predominant anion in secretions under all conditions studied and thus drives most of the fluid transport. Nevertheless, 50–70% of Cl− and fluid transport was bumetanide-insensitive, suggesting basolateral Cl− loading by a sodium–potassium–chloride cotransporter 1 (NKCC1)-independent mechanism. Imposing a transepithelial HCO3− gradient across basolaterally permeabilized Calu-3 cells sustained a forskolin-stimulated current, which was sensitive to CFTR inhibitors and drastically reduced in CFTR-deficient cells. Net HCO3− secretion was increased by bilateral Cl− removal and therefore did not require apical Cl−/HCO3− exchange. The results suggest a model in which most HCO3− is recycled basolaterally by exchange with Cl−, and the resulting HCO3−-dependent Cl− transport provides an osmotic driving force for

  17. Yield-stress fluid drop impact on heated surfaces

    NASA Astrophysics Data System (ADS)

    Blackwell, Brendan; Wu, Alex; Ewoldt, Randy

    2015-11-01

    Yield-stress fluids, including gels and pastes, are effectively fluid at high stress and solid at low stress. In liquid-solid impacts, these fluids can stick and accumulate where they impact, motivating several applications of these rheologically-complex materials. Here we use high-speed imaging to experimentally study liquid-solid impact of yield-stress fluids on heated surfaces. At low temperatures yield-stress fluids tend to stick to surfaces and leave a coating layer. At sufficiently high temperatures the Leidenfrost effect can be observed, wherein a layer of vapor is created between the material and the surface due to rapid boiling, which can prevent a droplet of yield-stress fluid from sticking to the surface. In this study rheological material properties, drop size, drop velocity, and surface temperature are varied to characterize behavioral regimes. Material sticking to and releasing from the surface is observed as a function of the input parameters.

  18. Motility of active fluid drops on surfaces

    NASA Astrophysics Data System (ADS)

    Khoromskaia, Diana; Alexander, Gareth P.

    2015-12-01

    Drops of active liquid crystal have recently shown the ability to self-propel, which was associated with topological defects in the orientation of active filaments [Sanchez et al., Nature 491, 431 (2013), 10.1038/nature11591]. Here, we study the onset and different aspects of motility of a three-dimensional drop of active fluid on a planar surface. We analyze theoretically how motility is affected by orientation profiles with defects of various types and locations, by the shape of the drop, and by surface friction at the substrate. In the scope of a thin drop approximation, we derive exact expressions for the flow in the drop that is generated by a given orientation profile. The flow has a natural decomposition into terms that depend entirely on the geometrical properties of the orientation profile, i.e., its bend and splay, and a term coupling the orientation to the shape of the drop. We find that asymmetric splay or bend generates a directed bulk flow and enables the drop to move, with maximal speeds achieved when the splay or bend is induced by a topological defect in the interior of the drop. In motile drops the direction and speed of self-propulsion is controlled by friction at the substrate.

  19. Lipoxin A4 Stimulates Calcium-Activated Chloride Currents and Increases Airway Surface Liquid Height in Normal and Cystic Fibrosis Airway Epithelia

    PubMed Central

    Al-Alawi, Mazen; Costello, Richard W.; McNally, Paul; Chiron, Raphaël; Harvey, Brian J.; Urbach, Valérie

    2012-01-01

    Cystic Fibrosis (CF) is a genetic disease characterised by a deficit in epithelial Cl− secretion which in the lung leads to airway dehydration and a reduced Airway Surface Liquid (ASL) height. The endogenous lipoxin LXA4 is a member of the newly identified eicosanoids playing a key role in ending the inflammatory process. Levels of LXA4 are reported to be decreased in the airways of patients with CF. We have previously shown that in normal human bronchial epithelial cells, LXA4 produced a rapid and transient increase in intracellular Ca2+. We have investigated, the effect of LXA4 on Cl− secretion and the functional consequences on ASL generation in bronchial epithelial cells obtained from CF and non-CF patient biopsies and in bronchial epithelial cell lines. We found that LXA4 stimulated a rapid intracellular Ca2+ increase in all of the different CF bronchial epithelial cells tested. In non-CF and CF bronchial epithelia, LXA4 stimulated whole-cell Cl− currents which were inhibited by NPPB (calcium-activated Cl− channel inhibitor), BAPTA-AM (chelator of intracellular Ca2+) but not by CFTRinh-172 (CFTR inhibitor). We found, using confocal imaging, that LXA4 increased the ASL height in non-CF and in CF airway bronchial epithelia. The LXA4 effect on ASL height was sensitive to bumetanide, an inhibitor of transepithelial Cl− secretion. The LXA4 stimulation of intracellular Ca2+, whole-cell Cl− currents, conductances and ASL height were inhibited by Boc-2, a specific antagonist of the ALX/FPR2 receptor. Our results provide, for the first time, evidence for a novel role of LXA4 in the stimulation of intracellular Ca2+ signalling leading to Ca2+-activated Cl− secretion and enhanced ASL height in non-CF and CF bronchial epithelia. PMID:22662206

  20. Early cystic fibrosis lung disease: Role of airway surface dehydration and lessons from preventive rehydration therapies in mice.

    PubMed

    Mall, Marcus A; Graeber, Simon Y; Stahl, Mirjam; Zhou-Suckow, Zhe

    2014-07-01

    Cystic fibrosis (CF) lung disease starts in the first months of life and remains one of the most common fatal hereditary diseases. Early therapeutic interventions may provide an opportunity to prevent irreversible lung damage and improve outcome. Airway surface dehydration is a key disease mechanism in CF, however, its role in the in vivo pathogenesis and as therapeutic target in early lung disease remains poorly understood. Mice with airway-specific overexpression of the epithelial Na(+) channel (βENaC-Tg) recapitulate airway surface dehydration and phenocopy CF lung disease. Recent studies in neonatal βENaC-Tg mice demonstrated that airway surface dehydration produces early mucus plugging in the absence of mucus hypersecretion, which triggers airway inflammation, promotes bacterial infection and causes early mortality. Preventive rehydration therapy with hypertonic saline or amiloride effectively reduced mucus plugging and mortality in neonatal βENaC-Tg mice. These results support clinical testing of preventive/early rehydration strategies in infants and young children with CF.

  1. Acidic pH increases airway surface liquid viscosity in cystic fibrosis

    PubMed Central

    Tang, Xiao Xiao; Ostedgaard, Lynda S.; Hoegger, Mark J.; Moninger, Thomas O.; Karp, Philip H.; McMenimen, James D.; Choudhury, Biswa; Varki, Ajit; Stoltz, David A.; Welsh, Michael J.

    2016-01-01

    Cystic fibrosis (CF) disrupts respiratory host defenses, allowing bacterial infection, inflammation, and mucus accumulation to progressively destroy the lungs. Our previous studies revealed that mucus with abnormal behavior impaired mucociliary transport in newborn CF piglets prior to the onset of secondary manifestations. To further investigate mucus abnormalities, here we studied airway surface liquid (ASL) collected from newborn piglets and ASL on cultured airway epithelia. Fluorescence recovery after photobleaching revealed that the viscosity of CF ASL was increased relative to that of non-CF ASL. CF ASL had a reduced pH, which was necessary and sufficient for genotype-dependent viscosity differences. The increased viscosity of CF ASL was not explained by pH-independent changes in HCO3– concentration, altered glycosylation, additional pH-induced disulfide bond formation, increased percentage of nonvolatile material, or increased sulfation. Treating acidic ASL with hypertonic saline or heparin largely reversed the increased viscosity, suggesting that acidic pH influences mucin electrostatic interactions. These findings link loss of cystic fibrosis transmembrane conductance regulator–dependent alkalinization to abnormal CF ASL. In addition, we found that increasing Ca2+ concentrations elevated ASL viscosity, in part, independently of pH. The results suggest that increasing pH, reducing Ca2+ concentration, and/or altering electrostatic interactions in ASL might benefit early CF. PMID:26808501

  2. Acidic pH increases airway surface liquid viscosity in cystic fibrosis.

    PubMed

    Tang, Xiao Xiao; Ostedgaard, Lynda S; Hoegger, Mark J; Moninger, Thomas O; Karp, Philip H; McMenimen, James D; Choudhury, Biswa; Varki, Ajit; Stoltz, David A; Welsh, Michael J

    2016-03-01

    Cystic fibrosis (CF) disrupts respiratory host defenses, allowing bacterial infection, inflammation, and mucus accumulation to progressively destroy the lungs. Our previous studies revealed that mucus with abnormal behavior impaired mucociliary transport in newborn CF piglets prior to the onset of secondary manifestations. To further investigate mucus abnormalities, here we studied airway surface liquid (ASL) collected from newborn piglets and ASL on cultured airway epithelia. Fluorescence recovery after photobleaching revealed that the viscosity of CF ASL was increased relative to that of non-CF ASL. CF ASL had a reduced pH, which was necessary and sufficient for genotype-dependent viscosity differences. The increased viscosity of CF ASL was not explained by pH-independent changes in HCO3- concentration, altered glycosylation, additional pH-induced disulfide bond formation, increased percentage of nonvolatile material, or increased sulfation. Treating acidic ASL with hypertonic saline or heparin largely reversed the increased viscosity, suggesting that acidic pH influences mucin electrostatic interactions. These findings link loss of cystic fibrosis transmembrane conductance regulator-dependent alkalinization to abnormal CF ASL. In addition, we found that increasing Ca2+ concentrations elevated ASL viscosity, in part, independently of pH. The results suggest that increasing pH, reducing Ca2+ concentration, and/or altering electrostatic interactions in ASL might benefit early CF.

  3. Luminal cholinergic signalling in airway lining fluid: a novel mechanism for activating chloride secretion via Ca2+-dependent Cl− and K+ channels

    PubMed Central

    Hollenhorst, Monika I; Lips, Katrin S; Wolff, Miriam; Wess, Jürgen; Gerbig, Stefanie; Takats, Zoltan; Kummer, Wolfgang; Fronius, Martin

    2012-01-01

    BACKGROUND AND PURPOSE Recent studies detected the expression of proteins involved in cholinergic metabolism in airway epithelial cells, although the function of this non-neuronal cholinergic system is not known in detail. Thus, this study focused on the effect of luminal ACh as a regulator of transepithelial ion transport in epithelial cells. EXPERIMENTAL APPROACH RT-PCR experiments were performed using mouse tracheal epithelial cells for ChAT and organic cation transporter (OCT) transcripts. Components of tracheal airway lining fluid were analysed with desorption electrospray ionization (DESI) MS. Effects of nicotine on mouse tracheal epithelial ion transport were examined with Ussing-chamber experiments. KEY RESULTS Transcripts encoding ChAT and OCT1–3 were detected in mouse tracheal epithelial cells. The DESI experiments identified ACh in the airway lining fluid. Luminal ACh induced an immediate, dose-dependent increase in the transepithelial ion current (EC50: 23.3 µM), characterized by a transient peak and sustained plateau current. This response was not affected by the Na+-channel inhibitor amiloride. The Cl−-channel inhibitor niflumic acid or the K+-channel blocker Ba2+ attenuated the ACh effect. The calcium ionophore A23187 mimicked the ACh effect. Luminal nicotine or muscarine increased the ion current. Experiments with receptor gene-deficient animals revealed the participation of muscarinic receptor subtypes M1 and M3. CONCLUSIONS AND IMPLICATIONS The presence of luminal ACh and activation of transepithelial ion currents by luminal ACh receptors identifies a novel non-neuronal cholinergic pathway in the airway lining fluid. This pathway could represent a novel drug target in the airways. PMID:22300281

  4. Density-functional theory for polar fluids at functionalized surfaces. I. Fluid-wall association

    NASA Astrophysics Data System (ADS)

    Tripathi, Sandeep; Chapman, Walter G.

    2003-12-01

    We present a novel perturbation density-functional theory (DFT) to describe adsorption of associating fluids on surfaces activated with polar sites to which fluid molecules can bond or associate, such as water adsorbing on activated carbon, silica, clay minerals, etc. Association is modeled within the framework of first order thermodynamic perturbation theory (TPT1). In this first of two papers, we explore in detail the changes brought about in a system due to fluid-wall (FW) association. Hence fluid-fluid association is not considered here. However, the theory can be coupled with existing DF theories of associating fluids to study the interplay between the wall-fluid and fluid-fluid association as is shown in a future paper by S. Tripathi. The proposed theory, in excellent agreement with simulations, shows that FW association significantly changes the fluid structure and adsorption behavior. The theory accurately predicts the distribution of bonded and nonbonded species away from the surface, adsorption characteristics and surface coverage over a range of conditions commonly found in several real systems. The most striking feature of the theory is that in addition to properties away from the wall, it also estimates the distribution of the fluid along the surface, or the three-dimensional (3D) structure, despite being one-dimensional (1D) in form.

  5. When sticky fluids don't stick: yield-stress fluid drops on heated surfaces

    NASA Astrophysics Data System (ADS)

    Blackwell, Brendan; Wu, Alex; Ewoldt, Randy

    2016-11-01

    Yield-stress fluids, including gels and pastes, are effectively fluid at high stress and solid at low stress. In liquid-solid impacts, these fluids can stick and accumulate where they impact; this sticky behavior motivates several applications of these rheologically-complex materials. Here we describe experiments with aqueous yield stress fluids that are more 'sticky' than water at room temperature (e.g. supporting larger coating thicknesses), but are less 'sticky' at higher temperatures. Specifically, we study the conditions for aqueous yield stress fluids to bounce and slide on heated surfaces when water sticks. Here we present high-speed imaging and color interferometry to observe the thickness of the vapor layer between the drop and the surface during both stick and non-stick events. We use these data to gain insight into the physics behind the phenomenon of the yield-stress fluids bouncing and sliding, rather than sticking, on hot surfaces.

  6. Airway reopening: Steadily propagating bubbles in buckled elastic tubes

    NASA Astrophysics Data System (ADS)

    Heil, Matthias; Hazel, Andrew L.

    2001-11-01

    Many pulmonary diseases result in the collapse and occlusion of parts of the lung by viscous fluid. The subsequent airway reopening is generally assumed to occur via the propagation of an air finger into the collapsed, fluid-filled part of the airway. The problem has some similarity to the scenario of the `first breath' when air has to enter the fluid-filled lungs of a newborn baby for the first time. We have developed the first three-dimensional computational model of airway reopening, based on a finite-element solution of the free-surface Stokes equations, fully coupled to the equations of large-displacement shell theory. Following a brief discussion of the numerical method, we will present results that illustrate the 3D flow field by which the steadily propagating air finger reopens the non-axisymmetrically collapsed airway. Finally, we will contrast the system's behaviour to predictions from earlier two-dimensional models.

  7. Influence of breathing route on upper airway lining liquid surface tension in humans

    PubMed Central

    Verma, Manisha; Seto-Poon, Margaret; Wheatley, John R; Amis, Terence C; Kirkness, Jason P

    2006-01-01

    We have recently demonstrated that the severity of sleep-disordered breathing in obstructive sleep apnoea hypopnoea syndrome (OSAHS) can be reduced by lowering the surface tension (γ) of the upper airway lining liquid (UAL). Morning xerostomia (related to oral breathing during sleep) is reported by most OSAHS patients. In the present study we examine relationships between breathing route, oral mucosal ‘wetness’ and the γ of UAL. We studied eight healthy subjects (age, 25 ± 5 years [mean ± s.d.]; body-mass index, 23 ± 2 kg m−2) during a 120 min challenge of both nasal-only breathing (mouth taped) and oral-only breathing (nose clip), each on a separate day (randomized). Both oral mucosal ‘wetness’ (5 s contact gravimetric absorbent paper strip method) and the γ (‘pull-off’ force technique) of 0.2 μl samples of UAL obtained from the posterior pharyngeal wall were measured at 15 min intervals (mouth tape removed and replaced as required). Upper airway mucosal ‘wetness’ increased during 120 min of nasal breathing from 4.0 ± 0.4 (mean ± s.e.m.) to 5.3 ± 0.3 μl (5 s)−1 but decreased from 4.5 ± 0.4 to 0.1 ± 0.2 μl (5 s)−1 with oral breathing (both P < 0.001, repeated-measures ANOVA, Tukey's multiple comparison test, post hoc test). Concurrently, the γ of UAL decreased from 59.3 ± 2.2 to 51.8 ± 0.98 mN m−1 with nasal breathing but increased from 64.4 ± 2.7 to 77.4 ± 1.1 mN m−1 with oral breathing (P < 0.001). For the group and all conditions studied, γ of UAL values strongly correlated with upper airway mucosal ‘wetness’ (correlation coefficient, r2=−0.34, P < 0.001; linear regression). We conclude that oral breathing increases and nasal breathing decreases the γ of UAL in healthy subjects during wakefulness. We speculate that nasal breathing in OSAHS patients during sleep may promote a low γ of UAL that may contribute to reducing the severity of sleep-disordered breathing. PMID:16690717

  8. Effects of smooth random surface on fluid monolayer thermodynamics

    NASA Astrophysics Data System (ADS)

    Khlyupin, A. N.

    2016-11-01

    We consider the lattice gas approach to statistical mechanics of fluid adsorbed on random surfaces with fluid-fluid and fluid-surface potentials. It was shown that effective Hamiltonian contains quenched random interactions and random site fields. Their statistical features combine the properties of random geometry and fluid-fluid pair interaction potential. The high-temperature expansion leads to infinite-ranged random field model and Sherrington-Kirkpatrick spin-glass model. Thermodynamic properties are evaluated using replica theory procedure widely used to analyze quenched disorder systems. On the other hand we consider the random field model in random graph with finite connectivity instead of previous “infinite-ranged” approximations. This model has been investigated using finite connectivity technique. The replica symmetry ansatz for the order function is expressed in terms of an effective-field distribution. Analysis of random geometry effects on thermodynamic properties in such approach was done for the first time.

  9. Surface tension driven flow in glass melts and model fluids

    NASA Technical Reports Server (NTRS)

    Mcneil, T. J.; Cole, R.; Subramanian, R. S.

    1982-01-01

    Surface tension driven flow has been investigated analytically and experimentally using an apparatus where a free column of molten glass or model fluids was supported at its top and bottom faces by solid surfaces. The glass used in the experiments was sodium diborate, and the model fluids were silicone oils. In both the model fluid and glass melt experiments, conclusive evidence was obtained to prove that the observed flow was driven primarily by surface tension forces. The experimental observations are in qualitative agreement with predictions from the theoretical model.

  10. Surface/Fluid Interactions in Micro and Nano-Channels

    DTIC Science & Technology

    2007-05-15

    05-2007 Final 01-01-2004 - 31-12-2006 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER SURFACE/FLUID INTERACTIONS IN MICRO & NANO -CHANNELS 5b. GRANT NUMBER...NOTES 14. ABSTRACT This research project investigates the dynamics of surface/fluid interactions that occur in micro - and nano -cnanneis. For example...ANSI Std. Z39.18 SURFACE/FLUID INTERACTIONS IN MICRO & NANO -CHANNELS AFSOR FA9950-04-0106 Carl D. Meinhart Department of Mechanical Engineering

  11. Simulation of the Velocity and Temperature Distribution of Inhalation Thermal Injury in a Human Upper Airway Model by Application of Computational Fluid Dynamics.

    PubMed

    Chang, Yang; Zhao, Xiao-zhuo; Wang, Cheng; Ning, Fang-gang; Zhang, Guo-an

    2015-01-01

    Inhalation injury is an important cause of death after thermal burns. This study was designed to simulate the velocity and temperature distribution of inhalation thermal injury in the upper airway in humans using computational fluid dynamics. Cervical computed tomography images of three Chinese adults were imported to Mimics software to produce three-dimensional models. After grids were established and boundary conditions were defined, the simulation time was set at 1 minute and the gas temperature was set to 80 to 320°C using ANSYS software (ANSYS, Canonsburg, PA) to simulate the velocity and temperature distribution of inhalation thermal injury. Cross-sections were cut at 2-mm intervals, and maximum airway temperature and velocity were recorded for each cross-section. The maximum velocity peaked in the lower part of the nasal cavity and then decreased with air flow. The velocities in the epiglottis and glottis were higher than those in the surrounding areas. Further, the maximum airway temperature decreased from the nasal cavity to the trachea. Computational fluid dynamics technology can be used to simulate the velocity and temperature distribution of inhaled heated air.

  12. Hot Surface Ignition Tests of Aircraft Fluids

    DTIC Science & Technology

    1988-11-01

    commionly f~und in aircraft engine components, JP-4 and JP-8 fuels, Mil-H-5606 and Mil-H-83282 hydraulic fluids and Mil-L-7808 lubricating oil , were tested in...4 and JP-8 fuels and Nil-L-7808 lubricating oil ) using an air- heated bleed-air du:t in a high realism test article. First, tests were conducted on a...JP-4 and JP-8 fuels, Mil-H.- 5606 and Mil-H-83282 hydraulic "J.,tids and Mil-L-7806 lubricating oil were injected as spray or streuins clto various

  13. Basolateral chloride loading by the anion exchanger type 2: role in fluid secretion by the human airway epithelial cell line Calu-3

    PubMed Central

    Huang, Junwei; Shan, Jiajie; Kim, Dusik; Liao, Jie; Evagelidis, Alexandra; Alper, Seth L; Hanrahan, John W

    2012-01-01

    Anion exchanger type 2 (AE2 or SLC4A2) is an electroneutral Cl−/HCO3− exchanger expressed at the basolateral membrane of many epithelia. It is thought to participate in fluid secretion by airway epithelia. However, the role of AE2 in fluid secretion remains uncertain, due to the lack of specific pharmacological inhibitors, and because it is electrically silent and therefore does not contribute directly to short-circuit current (Isc). We have studied the role of AE2 in Cl− and fluid secretion by the airway epithelial cell line Calu-3. After confirming expression of its mRNA and protein, a knock-down cell line called AE2-KD was generated by lentivirus-mediated RNA interference in which AE2 mRNA and protein levels were reduced ≥90%. Suppressing AE2 increased the expression of the cystic fibrosis transmembrane conductance regulator (CFTR) by ∼70% without affecting the levels of NKCC1 (Na+–K+–2Cl− cotransporter) or NBCe1 (Na+–nHCO3− cotransporter). cAMP agonists stimulated fluid secretion by parental Calu-3 and scrambled shRNA cells >6.5-fold. In AE2-KD cells this response was reduced by ∼70%, and the secreted fluid exhibited elevated pH and [HCO3−] as compared with the control lines. Unstimulated equivalent short-circuit current (Ieq) was elevated in AE2-KD cells, but the incremental response to forskolin was unaffected. The modest bumetanide-induced reductions in both Ieq and fluid secretion were more pronounced in AE2-KD cells. Basolateral Cl−/HCO3− exchange measured by basolateral pH-stat in cells with permeabilized apical membranes was abolished in AE2-KD monolayers, and the intracellular alkalinization resulting from basolateral Cl− removal was reduced by ∼80% in AE2-KD cells. These results identify AE2 as a major pathway for basolateral Cl− loading during cAMP-stimulated secretion of Cl− and fluid by Calu-3 cells, and help explain the large bumetanide-insensitive component of fluid secretion reported previously in airway

  14. Expression of surface platelet receptors (CD62P and CD41/61) in horses with recurrent airway obstruction (RAO).

    PubMed

    Iwaszko-Simonik, Alicja; Niedzwiedz, Artur; Graczyk, Stanislaw; Slowikowska, Malwina; Pliszczak-Krol, Aleksandra

    2015-03-15

    Recurrent airway obstruction (RAO) is an allergic disease of horses similar to human asthma, which is characterized by airway inflammation and activation of neutrophils, lymphocytes and platelets. Platelet activation and an increase in circulating platelet-leukocyte aggregates may lead to airway remodeling. The aim of this study was to investigate platelet status in RAO-affected horses based on the platelet morphology and platelet surface expression of CD41/61 and CD62P. Ten RAO-affected horses and ten healthy horses were included in this study. Blood samples were obtained to determine the platelet count (PLT), mean platelet volume (MPV) and platelet large cell ratio (P-LCR). Expression of CD62P and CD41/61 was detected by flow cytometry on activated platelets. The median PLT was significantly reduced in horses with RAO compared to the controls. The MPV and the P-LCR values were significantly higher in RAO horses than controls. Expression of CD41/61 on platelets was increased in RAO horses, while CD62P expression was reduced. This study demonstrated the morphological changes in platelets and expression of platelet surface receptors. Despite the decrease of CD62P expression, the observed increased surface expression of CD41/61 on platelets in horses with RAO may contribute to the formation of platelet aggregates in their respiratory system.

  15. Nanodrop of an Ising magnetic fluid on a solid surface.

    PubMed

    Berim, Gersh O; Ruckenstein, Eli

    2011-07-19

    The density functional theory of inhomogeneous simple fluids is extended to an Ising magnetic fluid in contact with a solid surface, which is subjected to an external uniform or nonuniform magnetic field. The system is described by two coupled integral equations regarding the magnetic moment and fluid density distributions. The dependence of the contact angle that a nanodrop makes with the solid surface on the parameters involved in the magnetic interactions between the molecules of fluid and between the molecules of fluid and an external magnetic field is calculated. For the uniform magnetic field, the contact angle increases with increasing magnetic field, approaching an asymptotic value that depends on the strength of the fluid-fluid magnetic interactions. In the nonuniform field generated by a permanent magnet, the contact angle first increases with increasing magnetic field B(M) and then decreases, with the decrease being almost linear for large values of B(M). The obtained results are in qualitative agreement with the experimental data on the contact angle of magnetic drops on a solid surface available in the literature.

  16. Engineered Multifunctional Surfaces for Fluid Handling

    NASA Technical Reports Server (NTRS)

    Thomas, Chris; Ma, Yonghui; Weislogel, Mark

    2012-01-01

    Designs incorporating variations in capillary geometry and hydrophilic and/or antibacterial surface properties have been developed that are capable of passive gas/liquid separation and passive water flow. These designs can incorporate capillary grooves and/or surfaces arranged to create linear and circumferential capillary geometry at the micro and macro scale, radial fin configurations, micro holes and patterns, and combinations of the above. The antibacterial property of this design inhibits the growth of bacteria or the development of biofilm. The hydrophilic property reduces the water contact angle with a treated substrate such that water spreads into a thin layer atop the treated surface. These antibacterial and hydrophilic properties applied to a thermally conductive surface, combined with capillary geometry, create a novel heat exchanger capable of condensing water from a humid, two-phase water and gas flow onto the treated heat exchanger surfaces, and passively separating the condensed water from the gas flow in a reduced gravity application. The overall process to generate the antibacterial and hydrophilic properties includes multiple steps to generate the two different surface properties, and can be divided into two major steps. Step 1 uses a magnetron-based sputtering technique to implant the silver atoms into the base material. A layer of silver is built up on top of the base material. Completion of this step provides the antibacterial property. Step 2 uses a cold-plasma technique to generate the hydrophilic surface property on top of the silver layer generated in Step 1. Completion of this step provides the hydrophilic property in addition to the antibacterial property. Thermally conductive materials are fabricated and then treated to create the antibacterial and hydrophilic surface properties. The individual parts are assembled to create a condensing heat exchanger with antibacterial and hydrophilic surface properties and capillary geometry, which is

  17. Generating Inviscid and Viscous Fluid-Flow Simulations over an Aircraft Surface Using a Fluid-Flow Mesh

    NASA Technical Reports Server (NTRS)

    Rodriguez, David L. (Inventor); Sturdza, Peter (Inventor)

    2013-01-01

    Fluid-flow simulation over a computer-generated aircraft surface is generated using inviscid and viscous simulations. A fluid-flow mesh of fluid cells is obtained. At least one inviscid fluid property for the fluid cells is determined using an inviscid fluid simulation that does not simulate fluid viscous effects. A set of intersecting fluid cells that intersects the aircraft surface are identified. One surface mesh polygon of the surface mesh is identified for each intersecting fluid cell. A boundary-layer prediction point for each identified surface mesh polygon is determined. At least one boundary-layer fluid property for each boundary-layer prediction point is determined using the at least one inviscid fluid property of the corresponding intersecting fluid cell and a boundary-layer simulation that simulates fluid viscous effects. At least one updated fluid property for at least one fluid cell is determined using the at least one boundary-layer fluid property and the inviscid fluid simulation.

  18. Containment of a silicone fluid free surface in reduced gravity

    NASA Technical Reports Server (NTRS)

    Pline, A.; Jacobson, T.

    1988-01-01

    In support of the surface tension driven convection experiment planned for flight aboard the Space Shuttle, tests were conducted under reduced gravity in the 2.2-sec drop tower and the 5.0-sec Zero-G facility at the Lewis Research Center. The dynamics of controlling the test fluid, a 10-centistoke viscosity silicone fluid, in a low-gravity environment were investigated using different container designs and barrier coatings. Three container edge designs were tested without a barrier coating: a square edge, a sharp edge with a 45-deg slope, and a saw-tooth edge. All three edge designs were successful in containing the fluid below the edge.

  19. Surface activity of Janus particles adsorbed at fluid-fluid interfaces: Theoretical and experimental aspects.

    PubMed

    Fernandez-Rodriguez, Miguel Angel; Rodriguez-Valverde, Miguel Angel; Cabrerizo-Vilchez, Miguel Angel; Hidalgo-Alvarez, Roque

    2016-07-01

    Since de Gennes coined in 1992 the term Janus particle (JP), there has been a continued effort to develop this field. The purpose of this review is to present the most relevant theoretical and experimental results obtained so far on the surface activity of amphiphilic JPs at fluid interfaces. The surface activity of JPs at fluid-fluid interfaces can be experimentally determined using two different methods: the classical Langmuir balance or the pendant drop tensiometry. The second method requires much less amount of sample than the first one, but it has also some experimental limitations. In all cases collected here the JPs exhibited a higher surface or interfacial activity than the corresponding homogeneous particles. This reveals the significant advantage of JPs for the stabilization of emulsions and foams.

  20. Fluid dynamics of liquids on Titans surface

    NASA Astrophysics Data System (ADS)

    Ori, Gian Gabriele; Marinangeli, Lucia; Baliva, Antonio; Bressan, Mario; Strom, Robert G.

    1998-10-01

    On the surface of Titan liquids can be present in three types of environments : (i) oceans, (ii) seas and lakes, and (iii) fluvial channels. The liquid in these environments will be affected by several types of motion: progressive (tidal) waves, wind-generated waves and unidirectional currents. The physical parameters of the liquid on Titans surface can be reconstructed using the Peng-Robinson equation of state. The total energy of the waves, both tidal and wind, depends on the gravity and liquid density ; both values are lower on Titan than on Earth. Thus, the same total energy will produce larger waves on Titan. This is also valid also for the progressive waves, as it is confirmed by the physical relationship between horizontal velocity, wave amplitude, and depth of the liquid. Wind-driven waves also will tend to be larger, because the viscosity of the liquid (which is lower on Titan) controls the deformation of the liquid under shear stress. Wind-generated waves would be rather large, but the dimension of the liquid basin limits the size of the waves ; in small lakes or seas the wave power cannot reach large values. Unidirectional currents are also affected by the liquid properties. Both the relations from driving and resting forces and the Reynolds number suggests that the flows exhibit a large erosional capacity and that, theoretically, a true fluvial network could be formed. However, caution should be exercised, because the cohesion of the sedimentary interface can armour bottom and induce laterally extensive, unchanelled sheet flows with small erosional capacity.

  1. Fluids of the ocular surface: concepts, functions and physics.

    PubMed

    Cher, Ivan

    2012-08-01

    General adoption of the ocular surface (OS) concept has advanced the therapy of the external eye. Fresh physical findings have prompted new concepts; examples taken from each section of the text are: (i) ever-present lipid sealant bridges the palpebral fissure capping the three-dimensional 'OS' sac. The muco-aqueous pool (MAP) is thus enclosed, secluded from atmosphere, evaporation mitigated. Hence, the OS is conceptually, a compartment. The term 'dacruon' (otherwise 'tear film') has been coined for the combined fluids of the OS, viz. lipid film and MAP. (ii) Investigative techniques of physics yield data on (say) surface tension and viscosity, and on functions such as anchorage of dacruon base to the varied mucosae of the OS, lubrication, renovation of intermarginal fluid layers as the eye opens after each blink, and refinement of optics and vision by the fluids attached to the cornea. (iii) Physical events in the opening eye produce the unique 'black line' phenomenon in which capillary force induces subsurface flows into thirsty menisci, bringing about parameniscal dark grooves, pupil-ward of each meniscus. Attenuation of fluorescein in the shallowed fluid gaps behind each groove makes the dye appear unilluminated ('black lines') relative to adjacent full-thickness MAP fluid glowing under cobalt-blue illumination. Isolated from cornea by grooves and gaps, the meniscal fluid cannot pass freely over the cornea. It therefore streams through the menisci to nasolacrimal outflow.

  2. Mechanosensitive ATP Release Maintains Proper Mucus Hydration of Airways

    PubMed Central

    Button, Brian; Okada, Seiko F.; Frederick, Charles Brandon; Thelin, William R.; Boucher, Richard C.

    2013-01-01

    The clearance of mucus from the airways protects the lungs from inhaled noxious and infectious materials. Proper hydration of the mucus layer enables efficient mucus clearance through beating of cilia on airway epithelial cells, and reduced clearance of excessively concentrated mucus occurs in patients with chronic obstructive pulmonary disease and cystic fibrosis. Key steps in the mucus transport process are airway epithelia sensing and responding to changes in mucus hydration. We reported that extracellular adenosine triphosphate (ATP) and adenosine were important luminal auto-crine and paracrine signals that regulated the hydration of the surface of human airway epithelial cultures through their action on apical membrane purinoceptors. Mucus hydration in human airway epithelial cultures was sensed by an interaction between cilia and the overlying mucus layer: Changes in mechanical strain, proportional to mucus hydration, regulated ATP release rates, adjusting fluid secretion to optimize mucus layer hydration. This system provided a feedback mechanism by which airways maintained mucus hydration in an optimum range for cilia propulsion. Understanding how airway epithelia can sense and respond to changes in mucus properties helps us to understand how the mucus clearance system protects the airways in health and how it fails in lung diseases such as cystic fibrosis. PMID:23757023

  3. Mechanosensitive ATP release maintains proper mucus hydration of airways.

    PubMed

    Button, Brian; Okada, Seiko F; Frederick, Charles Brandon; Thelin, William R; Boucher, Richard C

    2013-06-11

    The clearance of mucus from the airways protects the lungs from inhaled noxious and infectious materials. Proper hydration of the mucus layer enables efficient mucus clearance through beating of cilia on airway epithelial cells, and reduced clearance of excessively concentrated mucus occurs in patients with chronic obstructive pulmonary disease and cystic fibrosis. Key steps in the mucus transport process are airway epithelia sensing and responding to changes in mucus hydration. We reported that extracellular adenosine triphosphate (ATP) and adenosine were important luminal autocrine and paracrine signals that regulated the hydration of the surface of human airway epithelial cultures through their action on apical membrane purinoceptors. Mucus hydration in human airway epithelial cultures was sensed by an interaction between cilia and the overlying mucus layer: Changes in mechanical strain, proportional to mucus hydration, regulated ATP release rates, adjusting fluid secretion to optimize mucus layer hydration. This system provided a feedback mechanism by which airways maintained mucus hydration in an optimum range for cilia propulsion. Understanding how airway epithelia can sense and respond to changes in mucus properties helps us to understand how the mucus clearance system protects the airways in health and how it fails in lung diseases such as cystic fibrosis.

  4. Low level ozone exposure induces airways inflammation and modifies cell surface phenotypes in healthy humans

    EPA Science Inventory

    Background: The effects of low level ozone exposure (0.08 ppm) on pulmonary function in healthy young adults are well known, however much less is known about the inflammatory and immuno-modulatory effects oflow level ozone in the airways. Techniques such as induced sputum and flo...

  5. COMPUTER SIMULATIONS OF LUNG AIRWAY STRUCTURES USING DATA-DRIVEN SURFACE MODELING TECHNIQUES

    EPA Science Inventory

    ABSTRACT

    Knowledge of human lung morphology is a subject critical to many areas of medicine. The visualization of lung structures naturally lends itself to computer graphics modeling due to the large number of airways involved and the complexities of the branching systems...

  6. Three-dimensional reconstruction of upper airways from MDCT

    NASA Astrophysics Data System (ADS)

    Perchet, Diane; Fetita, Catalin; Preteux, Francoise

    2005-03-01

    Under the framework of clinical respiratory investigation, providing accurate modalities for morpho-functional analysis is essential for diagnosis improvement, surgical planning and follow-up. This paper focuses on the upper airways investigation and develops an automated approach for 3D mesh reconstruction from MDCT acquisitions. In order to overcome the difficulties related to the complex morphology of the upper airways and to the image gray level heterogeneity of the airway lumens and thin bony septa, the proposed 3D reconstruction methodology combines 2D segmentation and 3D surface regularization approaches. The segmentation algorithm relies on mathematical morphology theory and provides airway lumen robust discrimination from the surrounding tissues, while preserving the connectivity relationship between the different anatomical structures. The 3D regularization step uses an energy-based modeling in order to achieve a smooth and well-fitted 3D surface of the upper airways. An accurate 3D mesh representation of the reconstructed airways makes it possible to develop specific clinical applications such as virtual endoscopy, surgical planning and computer assisted intervention. In addition, building up patient-specific 3D models of upper airways is highly valuable for the study and design of inhaled medication delivery via computational fluid dynamics (CFD) simulations.

  7. Catheter-Based Sensing In The Airways

    NASA Astrophysics Data System (ADS)

    Fouke, J. M.; Saunders, K. G.

    1988-04-01

    Studies attempting to define the role of the respiratory tract in heating and humidifying inspired air point to the need for sensing many variables including airway wall and airstream temperatures, humidity, and surface fluid pH and osmolarity. In order to make such measurements in vivo in human volunteers, catheter based technologies must be exploited both to assure subject safety and subject comfort. Miniturization of the electrodes or sensors becomes a top priority. This paper describes the use of thin-film microelectronic technology to fabricate a miniature, flexible sensor which can be placed directly onto the surface of the airway to measure the electrical conductance of the fluids present. From this information the osmolarity of the surface fluid was calculated. Physiologic evaluation of the device and corroboration of the calculations was performed in mongrel dogs. We also describe the successful application of current thermistor technology for the thermal mapping of the airways in humans in order to characterize the dynamic intrathoracic events that occur during breathing. The thermal probe consisted of a flexible polyvinyl tube that contained fourteen small thermistors fixed into the catheter. Data have been obtained in dozens of people, both normal subjects and asthmatic patients, under a variety of interventions. These data have substantively advanced the study of asthma, a particularly troublesome chronic obstructive pulmonary disorder.

  8. A study of the surface motion on a turbulent fluid

    NASA Astrophysics Data System (ADS)

    Cheung, Cecil

    The motion of small particles floating on the surface of a turbulent fluid and the velocity fluctuations in the underlying fluid are studied experimentally. The aim of the experiment is to probe the characteristics of the surface turbulence. Another goal is to find out the relation between the two dimensional motion of the floating particles and the underlying three dimensional turbulence which drives the surface motion. A vertically oscillating grid produces a zero-mean-shear turbulent flow in a plexi-glass container filled with distilled water. Particle tracking from video images is used to study the motion of the particles floating on the surface. The turbulent flow in the bulk volume is studied by a light scattering technique known as homodyne photon correlation spectroscopy. The two measurements are then compared. For the surface motion, the root-mean-squared fluctuation of the velocity difference of pairs of particles separated by a distance R increases as the logarithm of R. In the fluid below the surface, the typical velocity difference over a length scale l apparently follows a power law l to the power of 0.75. This suggests that the interior flow is a transition from a random laminar flow (which gives an exponent of unity) to fully developed turbulence (with the exponent being 1/3). These results imply that there is no simple way to relate the surface turbulence to the volume turbulence. Nonetheless the experiment may help understand the spreading of surface contaminants over the ocean, which was the motivation of this study.

  9. Evaluation and comparison of nasal airway flow patterns among three subjects from Caucasian, Chinese and Indian ethnic groups using computational fluid dynamics simulation.

    PubMed

    Zhu, Jian Hua; Lee, Heow Pueh; Lim, Kian Meng; Lee, Shu Jin; Wang, De Yun

    2011-01-31

    Nasal airflow is one of the most important determinants for nasal physiology. During the long evolution of human beings, different races have developed their own attributes of nasal morphologies which result in variations of nasal airflow patterns and nasal functions. This study evaluated and compared the effects of differences of nasal morphology among three healthy male subjects from Caucasian, Chinese and Indian ethnic groups on nasal airflow patterns using computational fluid dynamics simulation. By examining the anterior nasal airway, the nasal indices and the nostril shapes of the three subjects were found to be similar to nasal cavities of respective ethnic groups. Computed tomography images of these three subjects were obtained to reconstruct 3-dimensional models of nasal cavities. To retain the flow characteristics around the nasal vestibules, a 40 mm-radius semi sphere was assembled around the human face for the prescription of zero ambient gauge pressure. The results show that more airflow tends to pass through the middle passage of the nasal airway in the Caucasian model, and through the inferior portion in the Indian model. The Indian model was found with extremely low flow flux flowing through the olfactory region. The sizes of vortexes near the anterior cavity were found to be correlated with the angles between the upper nasal valve wall and the anterior head of the nasal cavity.

  10. Fluid flow near the surface of earth's outer core

    NASA Technical Reports Server (NTRS)

    Bloxham, Jeremy; Jackson, Andrew

    1991-01-01

    This review examines the recent attempts at extracting information on the pattern of fluid flow near the surface of the outer core from the geomagnetic secular variation. Maps of the fluid flow at the core surface are important as they may provide some insight into the process of the geodynamo and may place useful constraints on geodynamo models. In contrast to the case of mantle convection, only very small lateral variations in core density are necessary to drive the flow; these density variations are, by several orders of magnitude, too small to be imaged seismically; therefore, the geomagnetic secular variation is utilized to infer the flow. As substantial differences exist between maps developed by different researchers, the possible underlying reasons for these differences are examined with particular attention given to the inherent problems of nonuniqueness.

  11. The flow of a compressible fluid past a curved surface

    NASA Technical Reports Server (NTRS)

    Kaplan, Carl

    1943-01-01

    An iteration method is employed to obtain the flow of a compressible fluid past a curved surface. The first approximation which leads to the Prandtl-Glauert rule, is based on the assumption that the flow differs but little from a pure translation. The iteration process then consists in improving this first approximation in order that it will apply to a flow differing from pure translatory motion to a greater degree. The method fails when the Mach number of the undisturbed stream reaches unity but permits a transition from subsonic to supersonic conditions without the appearance of a compression shock. The limiting value at which potential flow no longer exits is indicated by the apparent divergence of the power series representing the velocity of the fluid at the surface of the solid boundary.

  12. Surface tension effects on instability in viscoelastic respiratory fluids.

    PubMed

    Vasudevan, Muraari; Lange, Carlos F

    2007-02-01

    This paper establishes the mathematical formalism for the modeling of the mucus layer in the human trachea as a viscoelastic multiphase fluid system with surface tension with a view toward study of instability properties of the air-mucus system aimed at improving the design of new bioaerosol suppressing medication. The effects of surface tension, previously only conjectured and very poorly understood, are clearly established with quantitative relationships. Several very important physiological conclusions are obtained supporting one method of potential treatment and prevention of disease transmission by alteration of the mucus layer properties over other potential methods.

  13. Real-time non-invasive detection of inhalable particulates delivered into live mouse airways.

    PubMed

    Donnelley, Martin; Morgan, Kaye S; Fouras, Andreas; Skinner, William; Uesugi, Kentaro; Yagi, Naoto; Siu, Karen K W; Parsons, David W

    2009-07-01

    Fine non-biological particles small enough to be suspended in the air are continually inhaled as we breathe. These particles deposit on airway surfaces where they are either cleared by airway defences or can remain and affect lung health. Pollutant particles from vehicles, building processes and mineral and industrial dusts have the potential to cause both immediate and delayed health problems. Because of their small size, it has not been possible to non-invasively examine how individual particles deposit on live airways, or to consider how they behave on the airway surface after deposition. In this study, synchrotron phase-contrast X-ray imaging (PCXI) has been utilized to detect and monitor individual particle deposition. The in vitro detectability of a range of potentially respirable particulates was first determined. Of the particulates tested, only asbestos, quarry dust, fibreglass and galena (lead sulfate) were visible in vitro. These particulates were then examined after delivery into the nasal airway of live anaesthetized mice; all were detectable in vivo but each exhibited different surface appearances and behaviour along the airway surface. The two fibrous particulates appeared as agglomerations enveloped by fluid, while the non-fibrous particulates were present as individual particles. Synchrotron PCXI provides the unique ability to non-invasively detect and track deposition of individual particulates in live mouse airways. With further refinement of particulate sizing and delivery techniques, PCXI should provide a novel approach for live animal monitoring of airway particulates relevant to lung health.

  14. Fluid mechanics of biological surfaces and their technological application.

    PubMed

    Bechert, D W; Bruse, M; Hage, W; Meyer, R

    2000-04-01

    A survey is given on fluid-dynamic effects caused by the structure and properties of biological surfaces. It is demonstrated that the results of investigations aiming at technological applications can also provide insights into biophysical phenomena. Techniques are described both for reducing wall shear stresses and for controlling boundary-layer separation. (a) Wall shear stress reduction was investigated experimentally for various riblet surfaces including a shark skin replica. The latter consists of 800 plastic model scales with compliant anchoring. Hairy surfaces are also considered, and surfaces in which the no-slip condition is modified. Self-cleaning surfaces such as that of lotus leaves represent an interesting option to avoid fluid-dynamic deterioration by the agglomeration of dirt. An example of technological implementation is discussed for riblets in long-range commercial aircraft. (b) Separation control is also an important issue in biology. After a few brief comments on vortex generators, the mechanism of separation control by bird feathers is described in detail. Self-activated movable flaps (= artificial bird feathers) represent a high-lift system enhancing the maximum lift of airfoils by about 20%. This is achieved without perceivable deleterious effects under cruise conditions. Finally, flight experiments on an aircraft with laminar wing and movable flaps are presented.

  15. Textured-surface quartz resonator fluid density and viscosity monitor

    DOEpatents

    Martin, Stephen J.; Wiczer, James J.; Cernosek, Richard W.; Frye, Gregory C.; Gebert, Charles T.; Casaus, Leonard; Mitchell, Mary A.

    1998-08-25

    A pair of thickness-shear mode resonators, one smooth and one with a textured surface, allows fluid density and viscosity to be independently resolved. A textured surface, either randomly rough or regularly patterned, leads to trapping of liquid at the device surface. The synchronous motion of this trapped liquid with the oscillating device surface allows the device to weigh the liquid; this leads to an additional response that depends on liquid density. This additional response enables a pair of devices, one smooth and one textured, to independently resolve liquid density and viscosity; the difference in responses determines the density while the smooth device determines the density-viscosity product, and thus, the pair determines both density and viscosity.

  16. Fluid mobility over corrugated surfaces in the Stokes regime

    NASA Astrophysics Data System (ADS)

    Shelley, S. R.; Smith, J. D.; Hibbins, A. P.; Sambles, J. R.; Horsley, S. A. R.

    2016-08-01

    An exact solution is found for laminar fluid flow along the grooves of a family of surfaces whose shape is given by the Lambert W-function. This simple solution allows for the slip length in the direction parallel to the grooves to be calculated exactly. With this analytical model, we establish the regime of validity for a previously untested perturbation theory intended for calculating the surface mobility tensor of arbitrary periodic surfaces, finding that it compares well to the exact expression for nearly all choices of parameters of the conformal map. To test this perturbation theory further, the mobility tensor is evaluated for a simple sinusoidal surface for flow both parallel and perpendicular to the grooves, finding that the perturbation theory is less accurate in the latter of these two cases.

  17. Local mesh refinement for incompressible fluid flow with free surfaces

    SciTech Connect

    Terasaka, H.; Kajiwara, H.; Ogura, K.

    1995-09-01

    A new local mesh refinement (LMR) technique has been developed and applied to incompressible fluid flows with free surface boundaries. The LMR method embeds patches of fine grid in arbitrary regions of interest. Hence, more accurate solutions can be obtained with a lower number of computational cells. This method is very suitable for the simulation of free surface movements because free surface flow problems generally require a finer computational grid to obtain adequate results. By using this technique, one can place finer grids only near the surfaces, and therefore greatly reduce the total number of cells and computational costs. This paper introduces LMR3D, a three-dimensional incompressible flow analysis code. Numerical examples calculated with the code demonstrate well the advantages of the LMR method.

  18. Tear Film Mucins: Front Line Defenders of the Ocular Surface; Comparison with Airway and Gastrointestinal Tract Mucins

    PubMed Central

    Hodges, Robin R.; Dartt, Darlene A.

    2014-01-01

    The ocular surface including the cornea and conjunctiva and its overlying tear film are the first tissues of the eye to interact with the external environment. The tear film is complex containing multiple layers secreted by different glands and tissues. Each layer contains specific molecules and proteins that not only maintain the health of the cells on the ocular surface by providing nourishment and removal of waste products but also protect these cells from environment. A major protective mechanism that the corneal and conjunctival cells have developed is secretion of the innermost layer of the tear film, the mucous layer. Both the cornea and conjunctiva express membrane spanning mucins, whereas the conjunctiva also produces soluble mucins. The mucins present in the tear film serve to maintain the hydration of the ocular surface and to provide lubrication and anti-adhesive properties between the cells of the ocular surface and conjunctiva during the blink. A third function is to contribute to the epithelial barrier to prevent pathogens from binding to the ocular surface. This review will focus on the different types of mucins produced by the corneal and conjunctival epithelia. Also included in this review will be a presentation of the structure of mucins, regulation of mucin production, role of mucins in ocular surface diseases, and the differences in mucin production by the ocular surface, airways and gastrointestinal tract. PMID:23954166

  19. Structure, biomimetics, and fluid dynamics of fish skin surfaces*

    NASA Astrophysics Data System (ADS)

    Lauder, George V.; Wainwright, Dylan K.; Domel, August G.; Weaver, James C.; Wen, Li; Bertoldi, Katia

    2016-10-01

    The interface between the fluid environment and the surface of the body in swimming fishes is critical for both physiological and hydrodynamic functions. The skin surface in most species of fishes is covered with bony scales or toothlike denticles (in sharks). Despite the apparent importance of fish surfaces for understanding aquatic locomotion and near-surface boundary layer flows, relatively little attention has been paid to either the nature of surface textures in fishes or possible hydrodynamic effects of variation in roughness around the body surface within an individual and among species. Fish surfaces are remarkably diverse and in many bony fishes scales can have an intricate surface texture with projections, ridges, and comblike extensions. Shark denticles (or scales) are toothlike and project out of the skin to form a complexly textured surface that interacts with free-stream flow. Manufacturing biomimetic foils with fishlike surfaces allows hydrodynamic testing and we emphasize here the importance of dynamic test conditions where the effect of surface textures is assessed under conditions of self-propulsion. We show that simple two-dimensional foils with patterned cuts do not perform as well as a smooth control surface, but that biomimetic shark skin foils can swim at higher self-propelled speeds than smooth controls. When the arrangement of denticles on the foil surface is altered, we find that a staggered-overlapped pattern outperforms other arrangements. Flexible foils made of real shark skin outperform sanded controls when foils are moved with a biologically realistic motion program. We suggest that focus on the mechanisms of drag reduction by fish surfaces has been too limiting and an additional role of fish surface textures may be to alter leading edge vortices and flow patterns on moving surfaces in a way that enhances thrust. Analysis of water flow over an artificial shark skin foil under both static and dynamic conditions shows that a shear layer

  20. Allergic airway inflammation induces a pro-secretory epithelial ion transport phenotype in mice.

    PubMed

    Anagnostopoulou, P; Dai, L; Schatterny, J; Hirtz, S; Duerr, J; Mall, M A

    2010-12-01

    The airway epithelium is a central effector tissue in allergic inflammation and T-helper cell (Th) type 2-driven epithelial responses, such as mucus hypersecretion contribute to airflow obstruction in allergic airway disease. Previous in vitro studies demonstrated that Th2 cytokines also act as potent modulators of epithelial ion transport and fluid secretion, but the in vivo effect of allergic inflammation on airway ion transport remains unknown. We, therefore, induced allergic inflammation by intratracheal instillation of Aspergillus fumigatus extract or interleukin-13 in mice and determined effects on ion transport in native tracheal and bronchial tissues. We demonstrate that allergic inflammation enhanced basal Cl(-) secretion in both airway regions and inhibited epithelial Na(+) channel (ENaC)-mediated Na(+) absorption and increased Ca²(+)-dependent Cl(-) secretion in bronchi. Allergen-induced alterations in bronchial ion transport were associated with reduced transcript levels of α-, β- and γENaC, and were largely abrogated in signal transducer and activator of transcription (Stat)6(-/-) mice. Our studies demonstrate that Th2-dependent airway inflammation produced a pro-secretory ion transport phenotype in vivo, which was largely Stat6-dependent. These results suggest that Th2-mediated fluid secretion may improve airway surface hydration and clearance of mucus that is hypersecreted in allergic airway diseases such as asthma, and identify epithelial Stat6 signalling as a potential therapeutic target to promote mucus hydration and airway clearance.

  1. Tissue factor pathway inhibitor prevents airway obstruction, respiratory failure and death due to sulfur mustard analog inhalation

    SciTech Connect

    Rancourt, Raymond C. Veress, Livia A. Ahmad, Aftab Hendry-Hofer, Tara B. Rioux, Jacqueline S. Garlick, Rhonda B. White, Carl W.

    2013-10-01

    Sulfur mustard (SM) inhalation causes airway injury, with enhanced vascular permeability, coagulation, and airway obstruction. The objective of this study was to determine whether recombinant tissue factor pathway inhibitor (TFPI) could inhibit this pathogenic sequence. Methods: Rats were exposed to the SM analog 2-chloroethyl ethyl sulfide (CEES) via nose-only aerosol inhalation. One hour later, TFPI (1.5 mg/kg) in vehicle, or vehicle alone, was instilled into the trachea. Arterial O{sub 2} saturation was monitored using pulse oximetry. Twelve hours after exposure, animals were euthanized and bronchoalveolar lavage fluid (BALF) and plasma were analyzed for prothrombin, thrombin–antithrombin complex (TAT), active plasminogen activator inhibitor-1 (PAI-1) levels, and fluid fibrinolytic capacity. Lung steady-state PAI-1 mRNA was measured by RT-PCR analysis. Airway-capillary leak was estimated by BALF protein and IgM, and by pleural fluid measurement. In additional animals, airway cast formation was assessed by microdissection and immunohistochemical detection of airway fibrin. Results: Airway obstruction in the form of fibrin-containing casts was evident in central conducting airways of rats receiving CEES. TFPI decreased cast formation, and limited severe hypoxemia. Findings of reduced prothrombin consumption, and lower TAT complexes in BALF, demonstrated that TFPI acted to limit thrombin activation in airways. TFPI, however, did not appreciably affect CEES-induced airway protein leak, PAI-1 mRNA induction, or inhibition of the fibrinolytic activity present in airway surface liquid. Conclusions: Intratracheal administration of TFPI limits airway obstruction, improves gas exchange, and prevents mortality in rats with sulfur mustard-analog-induced acute lung injury. - Highlights: • TFPI administration to rats after mustard inhalation reduces airway cast formation. • Inhibition of thrombin activation is the likely mechanism for limiting casts. • Rats given TFPI

  2. Generating Inviscid and Viscous Fluid Flow Simulations over a Surface Using a Quasi-simultaneous Technique

    NASA Technical Reports Server (NTRS)

    Sturdza, Peter (Inventor); Martins-Rivas, Herve (Inventor); Suzuki, Yoshifumi (Inventor)

    2014-01-01

    A fluid-flow simulation over a computer-generated surface is generated using a quasi-simultaneous technique. The simulation includes a fluid-flow mesh of inviscid and boundary-layer fluid cells. An initial fluid property for an inviscid fluid cell is determined using an inviscid fluid simulation that does not simulate fluid viscous effects. An initial boundary-layer fluid property a boundary-layer fluid cell is determined using the initial fluid property and a viscous fluid simulation that simulates fluid viscous effects. An updated boundary-layer fluid property is determined for the boundary-layer fluid cell using the initial fluid property, initial boundary-layer fluid property, and an interaction law. The interaction law approximates the inviscid fluid simulation using a matrix of aerodynamic influence coefficients computed using a two-dimensional surface panel technique and a fluid-property vector. An updated fluid property is determined for the inviscid fluid cell using the updated boundary-layer fluid property.

  3. Surface chemistry modulates osteoblasts sensitivity to low fluid shear stress.

    PubMed

    Xing, Juan; Li, Yan; Lin, Manping; Wang, Jinfeng; Wu, Jinchuan; Ma, Yufei; Wang, Yuanliang; Yang, Li; Luo, Yanfeng

    2014-11-01

    Low fluid shear stress (FSS) is the mechanical environment encountered by osteoblasts in implanted bones or native bones of bed rest patients. High sensitivity of osteoblasts to low FSS is beneficial to osteogenesis. We hypothesize that this sensitivity might be regulated by chemical microenvironment provided by scaffolds. To confirm this hypothesis, self-assembled monolayers (SAMs) were used to provide various surface chemistries including OH, CH3 , and NH2 while parallel-plate fluid flow system produced low FSS (5 dynes/cm(2) ). Alterations in S-phase cell fraction, alkaline phosphatase activity, fibronectin (Fn), and collagen type I (COL I) secretion compared to those without FSS exposure were detected to characterize the sensitivity. Osteoblasts on OH and CH3 SAMs demonstrated obvious sensitivity while on NH2 SAMs negligible sensitivity was observed. Examination of the cell aspect ratio, orientation, and focal adhesions before and after FSS exposure indicates that the full spreading and robust focal adhesions on NH2 SAMs should be responsible for the negligible sensitivity through increasing the cell tolerance to low FSS. Despite the higher sensitivity, the Fn and COL I depositions on both OH and CH3 SAMs after FSS exposure were still less than on NH2 SAMs without FSS exposure. These results suggest that elaborate design of surface chemical compositions is essential for orchestration of surface chemistry with low FSS to realize both high sensitivity and high matrix secretion, facilitating the formation of functional bone tissues in implanted bone.

  4. Release of beryllium from mineral ores in artificial lung and skin surface fluids.

    PubMed

    Duling, Matthew G; Stefaniak, Aleksandr B; Lawrence, Robert B; Chipera, Steve J; Virji, M Abbas

    2012-06-01

    Exposure to some manufactured beryllium compounds via skin contact or inhalation can cause sensitization. A portion of sensitized persons who inhale beryllium may develop chronic beryllium disease (CBD). Little is understood about exposures to naturally occurring beryllium minerals. The purpose of this study was to assess the bioaccessibility of beryllium from bertrandite ore. Dissolution of bertrandite from two mine pits (Monitor and Blue Chalk) was evaluated for both the dermal and inhalation exposure pathways by determining bioaccessibility in artificial sweat (pH 5.3 and pH 6.5), airway lining fluid (SUF, pH 7.3), and alveolar macrophage phagolysosomal fluid (PSF, pH 4.5). Significantly more beryllium was released from Monitor pit ore than Blue Chalk pit ore in artificial sweat buffered to pH 5.3 (0.88 ± 0.01% vs. 0.36 ± 0.00%) and pH 6.5 (0.09 ± 0.00% vs. 0.03 ± 0.01%). Rates of beryllium released from the ores in artificial sweat were faster than previously measured for manufactured forms of beryllium (e.g., beryllium oxide), known to induce sensitization in mice. In SUF, levels of beryllium were below the analytical limit of detection. In PSF, beryllium dissolution was biphasic (initial rapid diffusion followed by latter slower surface reactions). During the latter phase, dissolution half-times were 1,400 to 2,000 days, and rate constants were ~7 × 10(-10) g/(cm(2)·day), indicating that bertrandite is persistent in the lung. These data indicate that it is prudent to control skin and inhalation exposures to bertrandite dusts.

  5. Hydroetching of high surface area ceramics using moist supercritical fluids

    DOEpatents

    Fryxell, Glen; Zemanian, Thomas S.

    2004-11-02

    Aerogels having a high density of hydroxyl groups and a more uniform pore size with fewer bottlenecks are described. The aerogel is exposed to a mixture of a supercritical fluid and water, whereupon the aerogel forms a high density of hydroxyl groups. The process also relaxes the aerogel into a more open uniform internal structure, in a process referred to as hydroetching. The hydroetching process removes bottlenecks from the aerogels, and forms the hydrogels into more standard pore sizes while preserving their high surface area.

  6. Theory of surface light scattering from a fluid-fluid interface with adsorbed polymeric surfactants

    NASA Astrophysics Data System (ADS)

    Buzza, D. M. A.; Jones, J. L.; McLeish, T. C. B.; Richards, R. W.

    1998-09-01

    We present a microscopic theory for the interfacial rheology of a fluid-fluid interface with adsorbed surfactant and calculate the effect of this on surface light scattering from the interface. We model the head and tail groups of the surfactant as polymer chains, a description that becomes increasingly accurate for large molecular weight surfactants, i.e., polymeric surfactants. Assuming high surface concentrations so that we have a double-sided polymer brush monolayer, we derive microscopic scaling expressions for the surface viscoelastic constants using the Alexander-deGennes model. Our results for the surface elastic constants agree with those in the literature, while the results for the viscous constants are new. We find that four elastic constants, i.e., γ (surface tension), ɛ (dilational elasticity), κ (bending modulus), λ (coupling constant), and three viscous constants, i.e., ɛ',κ',λ' (the viscous counterparts of ɛ, κ, and λ, respectively) are required for a general description of interfacial viscoelasticity (neglecting in-plane shear). In contrast to current phenomenological models, we find (1) there is no viscous counterpart to γ, i.e., γ'≡0; (2) there are two additional complex surface constants (i.e., λ+iωλ' and κ+iωκ') due to the finite thickness of the monolayer. Excellent agreement is found comparing our microscopic theory with measurements on diblock copolymer monolayers. We further derive the dispersion relation governing surface hydrodynamic modes and the power spectrum for surface quasielastic light scattering (SQELS) for a general interface parameterized by all the surface viscoelastic constants. Limiting results are presented for (1) liquid-air interfaces; (2) liquid-liquid interfaces with ultralow γ. The significant contribution of κ in the latter case opens up the possibility for a direct measurement of κ using SQELS for polymeric surfactant monolayers. Finally, we show that the coupling constant λ can lead to

  7. The relative roles of passive surface forces and active ion transport in the modulation of airway surface liquid volume and composition.

    PubMed

    Tarran, R; Grubb, B R; Gatzy, J T; Davis, C W; Boucher, R C

    2001-08-01

    Two hypotheses have been proposed recently that offer different views on the role of airway surface liquid (ASL) in lung defense. The "compositional" hypothesis predicts that ASL [NaCl] is kept low (<50 mM) by passive forces to permit antimicrobial factors to act as a chemical defense. The "volume" hypothesis predicts that ASL volume (height) is regulated isotonically by active ion transport to maintain efficient mechanical mucus clearance as the primary form of lung defense. To compare these hypotheses, we searched for roles for: (1) passive forces (surface tension, ciliary tip capillarity, Donnan, and nonionic osmolytes) in the regulation of ASL composition; and (2) active ion transport in ASL volume regulation. In primary human tracheobronchial cultures, we found no evidence that a low [NaCl] ASL could be produced by passive forces, or that nonionic osmolytes contributed substantially to ASL osmolality. Instead, we found that active ion transport regulated ASL volume (height), and that feedback existed between the ASL and airway epithelia to govern the rate of ion transport and volume absorption. The mucus layer acted as a "reservoir" to buffer periciliary liquid layer height (7 microm) at a level optimal for mucus transport by donating or accepting liquid to or from the periciliary liquid layer, respectively. These data favor the active ion transport/volume model hypothesis to describe ASL physiology.

  8. Flow of viscous fluid along a nonlinearly stretching curved surface

    NASA Astrophysics Data System (ADS)

    Sanni, K. M.; Asghar, S.; Jalil, M.; Okechi, N. F.

    This paper focuses on the flow of viscous fluid over a curved surface stretching with nonlinear power-law velocity. The boundary layer equations are transformed into ordinary differential equations using suitable non-dimensional transformations. These equations are solved numerically using shooting and Runge-Kutta (RK) methods. The impact of non-dimensional radius of curvature and power-law indices on the velocity field, the pressure and the skin friction coefficient are investigated. The results deduced for linear stretching are compared with the published work to validate the numerical procedure. The important findings are: (a) Slight variation of the curvature of the stretching sheet increases the velocity and the skin friction coefficient significantly. (b) The nonlinearity of the stretching velocity increases the skin friction. (c) The results for linear stretching and the flat surface are the special cases of this problem.

  9. Ultrasensitive surface-enhanced Raman scattering detection in common fluids

    PubMed Central

    Yang, Shikuan; Dai, Xianming; Stogin, Birgitt Boschitsch; Wong, Tak-Sing

    2016-01-01

    Detecting target analytes with high specificity and sensitivity in any fluid is of fundamental importance to analytical science and technology. Surface-enhanced Raman scattering (SERS) has proven to be capable of detecting single molecules with high specificity, but achieving single-molecule sensitivity in any highly diluted solutions remains a challenge. Here we demonstrate a universal platform that allows for the enrichment and delivery of analytes into the SERS-sensitive sites in both aqueous and nonaqueous fluids, and its subsequent quantitative detection of Rhodamine 6G (R6G) down to ∼75 fM level (10−15 mol⋅L−1). Our platform, termed slippery liquid-infused porous surface-enhanced Raman scattering (SLIPSERS), is based on a slippery, omniphobic substrate that enables the complete concentration of analytes and SERS substrates (e.g., Au nanoparticles) within an evaporating liquid droplet. Combining our SLIPSERS platform with a SERS mapping technique, we have systematically quantified the probability, p(c), of detecting R6G molecules at concentrations c ranging from 750 fM (p > 90%) down to 75 aM (10−18 mol⋅L−1) levels (p ≤ 1.4%). The ability to detect analytes down to attomolar level is the lowest limit of detection for any SERS-based detection reported thus far. We have shown that analytes present in liquid, solid, or air phases can be extracted using a suitable liquid solvent and subsequently detected through SLIPSERS. Based on this platform, we have further demonstrated ultrasensitive detection of chemical and biological molecules as well as environmental contaminants within a broad range of common fluids for potential applications related to analytical chemistry, molecular diagnostics, environmental monitoring, and national security. PMID:26719413

  10. Models of muco-ciliary transport and tracer dispersion in airway surface liquid

    NASA Astrophysics Data System (ADS)

    Smith, David; Blake, John; Gaffney, Eamonn

    2003-11-01

    The airways of the lungs are protected by a thin layer of mucus ( 5-15 microns) which traps dust and other pathogens. The mucus plaque is secreted by specialised epithelial cells, then transported axially towards the pharynx by the action of a dense mat of beating cilia. The cilia beat in a watery `periciliary liquid' (PCL). According to previous theoretical analysis, axial transport of PCL is relatively small, consistent with an impermeable epithelium. However, tracer dispersion experiments by Matsui et al. (1998) appear to show large axial transport, consistent with a highly permeable epithelium. The resolution of the question of the amount of absorption of PCL is related to the issue of the pathogensis of cystic fibrosis lung disease. We present the results of a new model of mucociliary transport which combines the best features of several very different previous models. We also present a model of tracer dispersion and show how this can be used to interpret the findings of Matsui et al. and relate them to our theoretical results.

  11. Tunable Surface Hydrophobicity and Fluid Transport through Nanoporous Membranes

    NASA Astrophysics Data System (ADS)

    Ostrowski, Joseph H. J.

    There are more than three billion people across the globe that struggle to obtain clean drinkable water. One of the most promising avenues for generating potable water is through reverse osmosis and nanofiltration. Both solutions require a semipermeable membrane that prohibits passage of unwanted solute particles but allows passage of the solvent. Atomically thin two-dimensional membranes based on porous graphene show great promise as semipermeable materials, but modeling fluid flow on length scales between the microscopic (nanometer and smaller) and macroscopic (micron and larger) regimes presents formidable challenges. This thesis explores both equilibrium and nonequilibrium aspects of this problem and develops new methodology for simulating systems away from thermal equilibrium. First, we hypothesize that there is a wetting penalty for water as it tries to breach a sheet of graphene that should be naturally hydrophobic. By using equilibrium molecular dynamics simulations, we show that the hydrophobicity depends sensitively on the degree of electrical doping, offering an opportunity to tune the hydrophobic effect of graphene using small amounts of doping. The wetting contact angle, a measure of hydrophobicity, changes dramatically with the voltage applied to single layer graphene. We find that the sensitivity of the hydrophobic effect to voltage depends not on hydrogen bonding motifs at the interface between graphene and water, but instead on a phenomenon known as electrowetting. The theory of electrowetting predicts that the difference in surface tensions that defines the contact angle is quartic in the voltage, rather than quadratic, as it would be in bilayer graphene or in a two-dimensional metal. To explore the nonequilibrium aspects of fluid passage through atomically thin membranes, we developed a molecular dynamics methodology for simulating fluid flow at constant flux based on Gauss's principle of least constraint. This method develops microscopic

  12. Surface tension dominates insect flight on fluid interfaces

    PubMed Central

    Mukundarajan, Haripriya; Bardon, Thibaut C.; Kim, Dong Hyun; Prakash, Manu

    2016-01-01

    ABSTRACT Flight on the 2D air–water interface, with body weight supported by surface tension, is a unique locomotion strategy well adapted for the environmental niche on the surface of water. Although previously described in aquatic insects like stoneflies, the biomechanics of interfacial flight has never been analysed. Here, we report interfacial flight as an adapted behaviour in waterlily beetles (Galerucella nymphaeae) which are also dexterous airborne fliers. We present the first quantitative biomechanical model of interfacial flight in insects, uncovering an intricate interplay of capillary, aerodynamic and neuromuscular forces. We show that waterlily beetles use their tarsal claws to attach themselves to the interface, via a fluid contact line pinned at the claw. We investigate the kinematics of interfacial flight trajectories using high-speed imaging and construct a mathematical model describing the flight dynamics. Our results show that non-linear surface tension forces make interfacial flight energetically expensive compared with airborne flight at the relatively high speeds characteristic of waterlily beetles, and cause chaotic dynamics to arise naturally in these regimes. We identify the crucial roles of capillary–gravity wave drag and oscillatory surface tension forces which dominate interfacial flight, showing that the air–water interface presents a radically modified force landscape for flapping wing flight compared with air. PMID:26936640

  13. Hydromagnetic Steady Flow of Maxwell Fluid over a Bidirectional Stretching Surface with Prescribed Surface Temperature and Prescribed Surface Heat Flux

    PubMed Central

    Shehzad, Sabir Ali; Alsaedi, Ahmad; Hayat, Tasawar

    2013-01-01

    This paper investigates the steady hydromagnetic three-dimensional boundary layer flow of Maxwell fluid over a bidirectional stretching surface. Both cases of prescribed surface temperature (PST) and prescribed surface heat flux (PHF) are considered. Computations are made for the velocities and temperatures. Results are plotted and analyzed for PST and PHF cases. Convergence analysis is presented for the velocities and temperatures. Comparison of PST and PHF cases is given and examined. PMID:23874523

  14. Mechanics of fluid flow over compliant wrinkled polymeric surfaces

    NASA Astrophysics Data System (ADS)

    Raayai, Shabnam; McKinley, Gareth; Boyce, Mary

    2014-03-01

    Skin friction coefficients (based on frontal area) of sharks and dolphins are lower than birds, fish and swimming beetles. By either exploiting flow-induced changes in their flexible skin or microscale textures, dolphins and sharks can change the structure of the fluid flow around them and thus reduce viscous drag forces on their bodies. Inspired by this ability, investigators have tried using compliant walls and riblet-like textures as drag reduction methods in aircraft and marine industries and have been able to achieve reductions up to 19%. Here we investigate flow-structure interaction and wrinkling of soft polymer surfaces that can emulate shark riblets and dolphin's flexible skin. Wrinkling arises spontaneously as the result of mismatched deformation of a thin stiff coating bound to a thick soft elastic substrate. Wrinkles can be fabricated by controlling the ratio of the stiffness of the coating and substrate, the applied displacement and the thickness of the coating. In this work we will examine the evolution in the kinematic structures associated with steady viscous flow over the polymer wrinkled surfaces and in particular compare the skin friction with corresponding results for flow over non-textured and rigid surfaces.

  15. Liquid secretion properties of airway submucosal glands

    PubMed Central

    Ballard, Stephen T; Inglis, Sarah K

    2004-01-01

    The tracheobronchial submucosal glands secrete liquid that is important for hydrating airway surfaces, supporting mucociliary transport, and serving as a fluid matrix for numerous secreted macromolecules including the gel-forming mucins. This review details the essential structural elements of airway glands and summarizes what is currently known regarding the ion transport processes responsible for producing the liquid component of gland secretion. Liquid secretion most likely arises from serous cells and is principally under neural control with muscarinic agonists, substance P, and vasoactive intestinal peptide (VIP) functioning as effective secretogogues. Liquid secretion is driven by the active transepithelial secretion of both Cl− and HCO3− and at least a portion of this process is mediated by the cystic fibrosis transmembrane conductance regulator (CFTR), which is highly expressed in glands. The potential role of submucosal glands in cystic fibrosis lung disease is discussed. PMID:14660706

  16. Relationship between airway reactivity induced by methacholine or ultrasonically nebulized distilled cold water and BAL fluid cellular constituents in patients with sulfur mustard gas-induced asthma.

    PubMed

    Emad, Ali; Emad, Yasaman

    2007-01-01

    The objective of this article was to evaluate the relationship between the bronchial reactivity to methacholine and distilled cold water and inflammatory bronchial alveolar lavage (BAL) cells in mustard gas-induced asthma. This was a randomized, crossover clinical study set in a university hospital. The patients were 17 veterans with mustard gas-induced asthma and 17 normal veterans as a control group. Inhalation challenges with ultrasonically nebulized distilled water and methacholine and BAL via bronchoscopy and were performed in all patients and subjects. All patients did sustain a 20% fall in FEV(1) after methacholine, whereas two of them did not with distilled cold water. The patients were sensitive to distilled cold water with a median PD20 of 8.44 +/- 6.55 mL and sensitive to methacholine with the median PC20 of 4.88 +/- 4.22 mg/mL. Significant correlation was found between PC20 of methacholine and PD20 of distilled cold water (r = -0.74, p = 0.005). The proportion of BAL macrophages was significantly lower in patients with asthma than in the control group (p = 0.001). The proportions of lymphocytes and neutrophils were similar in the two groups. The percentage of eosinophils was higher in BAL fluid from the asthmatics compared with that in BAL fluid from the control group (p < 0.001). The percentage of the BAL eosinophils significantly correlated with both PC20 of methacholine (r = - 0.58, p = 0.01) and PD20 of distilled cold water (r = -0.81, p = 0.002). No relationship between PC20 of methacholine or PD20 of distilled cold water was found for other inflammatory BAL cells. This study showed that in patients with mustard gas-induced asthma, the degree of airway responsiveness to both methacholine and distilled water was associated with the percentage of BAL eosinophils.

  17. Adenosine deaminase 1 and concentrative nucleoside transporters 2 and 3 regulate adenosine on the apical surface of human airway epithelia: implications for inflammatory lung diseases.

    PubMed

    Hirsh, Andrew J; Stonebraker, Jaclyn R; van Heusden, Catja A; Lazarowski, Eduardo R; Boucher, Richard C; Picher, Maryse

    2007-09-11

    Adenosine is a multifaceted signaling molecule mediating key aspects of innate and immune lung defenses. However, abnormally high airway adenosine levels exacerbate inflammatory lung diseases. This study identifies the mechanisms regulating adenosine elimination from the apical surface of human airway epithelia. Experiments conducted on polarized primary cultures of nasal and bronchial epithelial cells showed that extracellular adenosine is eliminated by surface metabolism and cellular uptake. The conversion of adenosine to inosine was completely inhibited by the adenosine deaminase 1 (ADA1) inhibitor erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA). The reaction exhibited Km and Vmax values of 24 microM and 0.14 nmol x min(-1) x cm(-2). ADA1 (not ADA2) mRNA was detected in human airway epithelia. The adenosine/mannitol permeability coefficient ratio (18/1) indicated a minor contribution of paracellular absorption. Adenosine uptake was Na+-dependent and was inhibited by the concentrative nucleoside transporter (CNT) blocker phloridzin but not by the equilibrative nucleoside transporter (ENT) blocker dipyridamole. Apparent Km and Vmax values were 17 microM and 7.2 nmol x min(-1) x cm(-2), and transport selectivity was adenosine = inosine = uridine > guanosine = cytidine > thymidine. CNT3 mRNA was detected throughout the airways, while CNT2 was restricted to nasal epithelia. Inhibition of adenosine elimination by EHNA or phloridzin raised apical adenosine levels by >3-fold and stimulated IL-13 and MCP-1 secretion by 6-fold. These responses were reproduced by the adenosine receptor agonist 5'-(N-ethylcarboxamido)adenosine (NECA) and blocked by the adenosine receptor antagonist, 8-(p-sulfophenyl) theophylline (8-SPT). This study shows that adenosine elimination on human airway epithelia is mediated by ADA1, CNT2, and CNT3, which constitute important regulators of adenosine-mediated inflammation.

  18. Hyperglycaemia and Pseudomonas aeruginosa acidify cystic fibrosis airway surface liquid by elevating epithelial monocarboxylate transporter 2 dependent lactate-H+ secretion

    PubMed Central

    Garnett, James Peter; Kalsi, Kameljit K.; Sobotta, Mirko; Bearham, Jade; Carr, Georgina; Powell, Jason; Brodlie, Malcolm; Ward, Christopher; Tarran, Robert; Baines, Deborah L.

    2016-01-01

    The cystic fibrosis (CF) airway surface liquid (ASL) provides a nutrient rich environment for bacterial growth including elevated glucose, which together with defective bacterial killing due to aberrant HCO3− transport and acidic ASL, make the CF airways susceptible to colonisation by respiratory pathogens such as Pseudomonas aeruginosa. Approximately half of adults with CF have CF related diabetes (CFRD) and this is associated with increased respiratory decline. CF ASL contains elevated lactate concentrations and hyperglycaemia can also increase ASL lactate. We show that primary human bronchial epithelial (HBE) cells secrete lactate into ASL, which is elevated in hyperglycaemia. This leads to ASL acidification in CFHBE, which could only be mimicked in non-CF HBE following HCO3− removal. Hyperglycaemia-induced changes in ASL lactate and pH were exacerbated by the presence of P. aeruginosa and were attenuated by inhibition of monocarboxylate lactate-H+ co-transporters (MCTs) with AR-C155858. We conclude that hyperglycaemia and P. aeruginosa induce a metabolic shift which increases lactate generation and efflux into ASL via epithelial MCT2 transporters. Normal airways compensate for MCT-driven H+ secretion by secreting HCO3−, a process which is dysfunctional in CF airway epithelium leading to ASL acidification and that these processes may contribute to worsening respiratory disease in CFRD. PMID:27897253

  19. Hyperglycaemia and Pseudomonas aeruginosa acidify cystic fibrosis airway surface liquid by elevating epithelial monocarboxylate transporter 2 dependent lactate-H(+) secretion.

    PubMed

    Garnett, James Peter; Kalsi, Kameljit K; Sobotta, Mirko; Bearham, Jade; Carr, Georgina; Powell, Jason; Brodlie, Malcolm; Ward, Christopher; Tarran, Robert; Baines, Deborah L

    2016-11-29

    The cystic fibrosis (CF) airway surface liquid (ASL) provides a nutrient rich environment for bacterial growth including elevated glucose, which together with defective bacterial killing due to aberrant HCO3(-) transport and acidic ASL, make the CF airways susceptible to colonisation by respiratory pathogens such as Pseudomonas aeruginosa. Approximately half of adults with CF have CF related diabetes (CFRD) and this is associated with increased respiratory decline. CF ASL contains elevated lactate concentrations and hyperglycaemia can also increase ASL lactate. We show that primary human bronchial epithelial (HBE) cells secrete lactate into ASL, which is elevated in hyperglycaemia. This leads to ASL acidification in CFHBE, which could only be mimicked in non-CF HBE following HCO3(-) removal. Hyperglycaemia-induced changes in ASL lactate and pH were exacerbated by the presence of P. aeruginosa and were attenuated by inhibition of monocarboxylate lactate-H(+) co-transporters (MCTs) with AR-C155858. We conclude that hyperglycaemia and P. aeruginosa induce a metabolic shift which increases lactate generation and efflux into ASL via epithelial MCT2 transporters. Normal airways compensate for MCT-driven H(+) secretion by secreting HCO3(-), a process which is dysfunctional in CF airway epithelium leading to ASL acidification and that these processes may contribute to worsening respiratory disease in CFRD.

  20. SGLT1 activity in lung alveolar cells of diabetic rats modulates airway surface liquid glucose concentration and bacterial proliferation

    PubMed Central

    Oliveira, Tales Lyra; Candeia-Medeiros, Návylla; Cavalcante-Araújo, Polliane M.; Melo, Igor Santana; Fávaro-Pípi, Elaine; Fátima, Luciana Alves; Rocha, Antônio Augusto; Goulart, Luiz Ricardo; Machado, Ubiratan Fabres; Campos, Ruy R.; Sabino-Silva, Robinson

    2016-01-01

    High glucose concentration in the airway surface liquid (ASL) is an important feature of diabetes that predisposes to respiratory infections. We investigated the role of alveolar epithelial SGLT1 activity on ASL glucose concentration and bacterial proliferation. Non-diabetic and diabetic rats were intranasally treated with saline, isoproterenol (to increase SGLT1 activity) or phlorizin (to decrease SGLT1 activity); 2 hours later, glucose concentration and bacterial proliferation (methicillin-resistant Sthaphylococcus aureus, MRSA and Pseudomonas aeruginosa, P. aeruginosa) were analyzed in bronchoalveolar lavage (BAL); and alveolar SGLT1 was analyzed by immunohistochemistry. BAL glucose concentration and bacterial proliferation increased in diabetic animals: isoproterenol stimulated SGLT1 migration to luminal membrane, and reduced (50%) the BAL glucose concentration; whereas phlorizin increased the BAL glucose concentration (100%). These regulations were accompanied by parallel changes of in vitro MRSA and P. aeruginosa proliferation in BAL (r = 0.9651 and r = 0.9613, respectively, Pearson correlation). The same regulations were observed in in vivo P. aeruginosa proliferation. In summary, the results indicate a relationship among SGLT1 activity, ASL glucose concentration and pulmonary bacterial proliferation. Besides, the study highlights that, in situations of pulmonary infection risk, such as in diabetic subjects, increased SGLT1 activity may prevent bacterial proliferation whereas decreased SGLT1 activity can exacerbate it. PMID:26902517

  1. Clinical applications of image-based airway computational fluid dynamics: assessment of inhalation medication and endobronchial devices

    NASA Astrophysics Data System (ADS)

    De Backer, Jan W.; Vos, Wim G.; Germonpré, Paul; Salgado, Rodrigo; Parizel, Paul M.; De Backer, Wilfried

    2009-02-01

    Computational fluid dynamics (CFD) is a technique that is used increasingly in the biomedical field. Solving the flow equations numerically provides a convenient way to assess the efficiency of therapies and devices, ranging from cardiovascular stents and heart valves to hemodialysis workflows. Also in the respiratory field CFD has gained increasing interest, especially through the combination of three dimensional image reconstruction which results in highend patient-specific models. This paper provides an overview of clinical applications of CFD through image based modeling, resulting from recent studies performed in our center. We focused on two applications: assessment of the efficiency of inhalation medication and analysis of endobronchial valve placement. In the first application we assessed the mode of action of a novel bronchodilator in 10 treated patients and 4 controls. We assessed the local volume increase and resistance change based on the combination of imaging and CFD. We found a good correlation between the changes in volume and resistance coming from the CFD results and the clinical tests. In the second application we assessed the placement and effect of one way endobronchial valves on respiratory function in 6 patients. We found a strong patientspecific result of the therapy where in some patients the therapy resulted in complete atelectasis of the target lobe while in others the lobe remained inflated. We concluded from these applications that CFD can provide a better insight into clinically relevant therapies.

  2. Nonatopic asthma: in vivo airway hyperreactivity adoptively transferred to naive mice by THY-1(+) and B220(+) antigen-specific cells that lack surface expression of CD3.

    PubMed Central

    Geba, G P; Wegner, C D; Wolyniec, W W; Li, Y; Askenase, P W

    1997-01-01

    To investigate the cellular immune events contributing to airway hyperreactivity (AHR), we studied an in vivo mouse model induced by the hapten picryl (trinitrophenyl) chloride (PCl). Mice were immunized by cutaneous contact sensitization with PCl and airway challenged subsequently with picryl sulfonic acid (PSA) antigen (Ag). Increased airway resistance was produced late (24 h) after Ag challenge, disappeared by 48 h, and was associated with no decrease in diffusion capacity. AHR could be produced in PCl immune/ PSA challenged mice on day 7 or even, with challenge, as early as 1 d after contact sensitization, after adoptive transfer of immune cells lacking CD3(+) contact sensitivity effector T cells, or after transfer of Ag-specific lymphoid cells depleted of conventional T lymphocytes with surface determinants for CD3, CD4, CD8, TCR-beta, or TCR-delta molecules. Further experiments showed that development of AHR depended upon transfer of immune cells expressing surface membrane Thy-1 and B220 (CD45RA) determinants. We concluded that a novel population of Ag-specific lymphoid cells with a defined surface phenotype (Thy-1(+), CD3(-), CD4(-), CD8(-), TCR-alphabeta-, TCR-gammadelta-, and CD45RA+) is required in a mouse model for the development of AHR. PMID:9241124

  3. Defective postsecretory maturation of MUC5B mucin in cystic fibrosis airways

    PubMed Central

    Abdullah, Lubna H.; Evans, Jessica R.; Wang, T. Tiffany; Ford, Amina A.; Makhov, Alexander M.; Nguyen, Kristine; Coakley, Raymond D.; Griffith, Jack D.; Davis, C. William; Ballard, Stephen T.

    2017-01-01

    In cystic fibrosis (CF), airway mucus becomes thick and viscous, and its clearance from the airways is impaired. The gel-forming mucins undergo an ordered “unpacking/maturation” process after granular release that requires an optimum postsecretory environment, including hydration and pH. We hypothesized that this unpacking process is compromised in the CF lung due to abnormal transepithelial fluid transport that reduces airway surface hydration and alters ionic composition. Using human tracheobronchial epithelial cells derived from non-CF and CF donors and mucus samples from human subjects and domestic pigs, we investigated the process of postsecretory mucin unfolding/maturation, how these processes are defective in CF airways, and the probable mechanism underlying defective unfolding. First, we found that mucins released into a normal lung environment transform from a compact granular form to a linear form. Second, we demonstrated that this maturation process is defective in the CF airway environment. Finally, we demonstrated that independent of HCO3− and pH levels, airway surface dehydration was the major determinant of this abnormal unfolding process. This defective unfolding/maturation process after granular release suggests that the CF extracellular environment is ion/water depleted and likely contributes to abnormal mucus properties in CF airways prior to infection and inflammation. PMID:28352653

  4. A density functional theory for association of fluid molecules with a functionalized surface: fluid-wall single and double bonding

    NASA Astrophysics Data System (ADS)

    Haghmoradi, Amin; Wang, Le; Chapman, Walter G.

    2017-02-01

    In this manuscript we extend Wertheim’s two-density formalism beyond its first order to model a system of fluid molecules with a single association site close to a planar hard wall with association sites on its surface in a density functional theory framework. The association sites of the fluid molecules are small enough that they can form only one bond, while the wall association sites are large enough to bond with more than one fluid molecule. The effects of temperature and of bulk fluid and wall site densities on the fluid density profile, extent of association, and competition between single and double bonding of fluid segments at the wall sites versus distance from the wall are presented. The theory predictions are compared with new Monte Carlo simulation results and they are in good agreement. The theory captures the surface coverage over wide ranges of temperature and bulk density by introducing the effect of steric hindrance in fluid association at a wall site.

  5. Biomechanics of liquid-epithelium interactions in pulmonary airways

    PubMed Central

    Ghadiali, Samir N.; Gaver, Donald P.

    2008-01-01

    The delicate structure of the lung epithelium makes it susceptible to surface tension induced injury. For example, the cyclic reopening of collapsed and/or fluid-filled airways during the ventilation of injured lungs generates hydrodynamic forces that further damage the epithelium and exacerbate lung injury. The interactions responsible for epithelial injury during airway reopening are fundamentally multiscale, since air-liquid interfacial dynamics affect global lung mechanics, while surface tension forces operate at the molecular and cellular scales. This article will review the current state-of-knowledge regarding the effect of surface tension forces on a) the mechanics of airway reopening and b) epithelial cell injury. Due to the complex nature of the liquid-epithelium system, a combination of computational and experimental techniques are being used to elucidate the mechanisms of surface-tension induced lung injury. Continued research is leading to an integrated understanding of the biomechanical and biological interactions responsible for cellular injury during airway reopening. This information may lead to novel therapies that minimize ventilation induced lung injury. PMID:18511356

  6. Effects of second hand smoke on airway secretion and mucociliary clearance

    PubMed Central

    Liu, Yanyan; Di, Y. Peter

    2012-01-01

    The airway acts as the first defense against inhaled pathogens and particulate matter from the environment. One major way for the airway to clear inhaled foreign objects is through mucociliary clearance (MCC), an important component of the respiratory innate immune defense against lung disease. MCC is characterized by the upward movement of mucus by ciliary motion that requires a balance between the volume and composition of the mucus, adequate periciliary liquid (PCL) volume, and normal ciliary beat frequency (CBF). Airway surface fluid (ASL) is a thin layer liquid that consists of the highly viscous mucus upper “gel” layer, and the watery lubricating lower “sol” layer. Mucus production, secretion and clearance are considered to play a critical role in maintenance of airway health because it maintains hydration in the airway and traps particulates, bacteria, and viruses. Different types of epithelial cells, including secretory cells, and ciliated cells, contribute to the MCC function. Cigarette smoke (CS) contains chemicals and particulates that significantly affect airway secretion. Active and passive CS-induced chronic obstructive pulmonary disease (COPD) is frequently associated with hyperplasia of goblet cells and submucosal glands (SMGs), thus increasing the secretory capacity of the airways that impairs MCC. PMID:22973232

  7. Critical Steady Surface Waves of Idea Fluid over a Bump with Surface Tension

    NASA Astrophysics Data System (ADS)

    Choi, Jeongwhan; Lee, Sangwon; Kim, Joonkyoung; Whang, Sungim

    2016-11-01

    The paper deals with steady forced surface waves propagating on a two-dimensional incompressible and inviscid fluid with a small bump placed on a rigid flat bottom. If the surface tension coefficient T on the free surface is not zero and the wave is moving with a constant speed C, the wave motion is determined by two non-dimensional constants, F = √ gh and I = T / (ρgh 2) , where g is the gravity constant and h is the height of the fluid at infinity. It has been known that F = 1 and t = 1/3 are the critical values of F and t, respectively. In the critical case F = 1 + λ 1 ɛ 2 and t = 1/3 + t1 ɛ with ɛ > 0 a small parameter, a time-dependent forced Kawahara (F-Kawahara)equation is derived to model the wave propagation on the free surface and the steady F-Kawahara equation is studied both theoretically and merically. It is shown that the steady F-Kawahara equation has many different kinds of one and multi-hump solutions when t1 and λ 1 vary. In particular, for a fixed t 1, there is a λ 0 < 0 such that if λ 1 < λ 0 , two one-hump steady solutions can be obtained, one with small amplitude and the other with large amplitude. By using the unsteady F-Kawahara equation, it appears that the small one-hump solution is stable while the large one is nstable. In addition, two-hump solutions are unstable.

  8. Surface tension measurement techniques of magnetic fluids at an interface between different fluids using perpendicular field instability

    NASA Astrophysics Data System (ADS)

    Amin, M. Shahrooz; Elborai, Shihab; Lee, Se-Hee; He, Xiaowei; Zahn, Markus

    2005-05-01

    Two measurement techniques to determine the surface tension of ferrofluids using the perpendicular field instability are described. Four ferrofluid layers were examined with magnetic field applied perpendicularly to the surface of (1) oil-based ferrofluid in air; (2) water-based ferrofluid in air, (3) oil-based ferrofluid, and (4) fluorocarbon-based ferrofluid, both below a blend of 50% n-Propyl alcohol and 50% deionized water (propanol). Surface tension was accurately calculated by utilizing the measured Taylor wavelength from measurements of incipient fluid instability peaks and the measured densities of fluids. For cases (1) and (2), the calculated surface tension values were in good agreement with a tensiometer measurement. No accurate tensiometer measurements were conducted for the superposed liquids (3) and (4) since accurate tensiometer measurements are difficult for a two fluid layer system. The second less accurate method used the ferrofluid's nonlinear Langevin magnetization characteristics to compute the surface tension from incipience of interfacial instability conditions. Discrepancies between the surface tensions measured by the two methods were probably due to the ferrofluid particle size distributions and the strong dependence of the ferrofluid magnetization on particle size.

  9. Correlation and discriminant analysis between clinical, endoscopic, thoracic X-ray and bronchoalveolar lavage fluid cytology scores, for staging horses with recurrent airway obstruction (RAO).

    PubMed

    Tilley, P; Sales Luis, J P; Branco Ferreira, M

    2012-10-01

    As recurrent airway obstruction (RAO) is progressive and as medical history is frequently unknown by owners, it's important to suggest a score model to characterize RAO stages for a more accurate diagnosis and treatment. The authors correlated clinical (CS), endoscopic (ES), thoracic X-ray (XRS) and bronchoalveolar lavage fluid (BALFS) scores in horses with RAO, in an attempt to establish relevance of each factor's contribution for the characterization of RAO stages and to suggest a staging method. Thirty horses with RAO and ten healthy controls were studied. Pearson correlation coefficients were determined between CS, ES, XRS and BALFS. Only significant correlation coefficients (>0.60) were considered. One way variance analyses were used to compare the two groups. A discriminant analysis model was adjusted on the RAO staging method suggested. There was a significant correlation coefficient between the CS cough, nostril flare and abdominal lift, all the mucus ES (0.61-0.84), the XRS interstitial pattern, bronchial radiopacity and thickening and tracheal thickening (0.67-0.78) and the BALFS neutrophil percentages (0.63-0.84). These variables (e.g., cough) which presented a significant correlation coefficient were considered relevant and chosen for a score model to characterize RAO stages. The ten healthy controls were attributed stage 0 and the 30 RAO horses were attributed stages 1 (4 horses), 2 (7 horses), 3 (10 horses) and 4 (9 horses). There was also a significant correlation coefficient between all the relevant variables and the RAO stage (0.61-0.89). Furthermore, discriminant analysis of the RAO staging method showed 92.5% of original grouped cases and 85.0% of cross-validated grouped cases correctly classified, having confirmed major contribution of the same variables that had significant correlation coefficients. Even though further confirmation by lung functional testing is desirable, the significant correlation between relevant variables and RAO stage and

  10. Manipulation of fluids in three-dimensional porous photonic structures with patterned surface properties

    DOEpatents

    Aizenberg, Joanna; Burgess, Ian B.; Mishchenko, Lidiya; Hatton, Benjamin; Loncar, Marko

    2016-03-08

    A three-dimensional porous photonic structure, whose internal pore surfaces can be provided with desired surface properties in a spatially selective manner with arbitrary patterns, and methods for making the same are described. When exposed to a fluid (e.g., via immersion or wicking), the fluid can selectively penetrate the regions of the structure with compatible surface properties. Broad applications, for example in security, encryption and document authentication, as well as in areas such as simple microfluidics and diagnostics, are anticipated.

  11. Identifying two regimes of slip of simple fluids over smooth surfaces with weak and strong wall-fluid interaction energies

    NASA Astrophysics Data System (ADS)

    Hu, Haibao; Bao, Luyao; Priezjev, Nikolai V.; Luo, Kai

    2017-01-01

    The slip behavior of simple fluids over atomically smooth surfaces was investigated in a wide range of wall-fluid interaction (WFI) energies at low shear rates using non-equilibrium molecular dynamics simulations. The relationship between slip and WFI shows two regimes (the strong-WFI and weak-WFI regimes): as WFI decreases, the slip length increases in the strong-WFI regime and decreases in the weak-WFI regime. The critical value of WFI energy that separates these regimes increases with temperature, but it remains unaffected by the driving force. The mechanism of slip was analyzed by examining the density-weighted average energy barrier ( Δ E ¯ ) encountered by fluid atoms in the first fluid layer (FFL) during their hopping between minima of the surface potential. We demonstrated that the relationship between slip and WFI can be rationalized by considering the effect of the fluid density distribution in the FFL on Δ E ¯ as a function of the WFI energy. Moreover, the dependence of the slip length on WFI and temperature is well correlated with the exponential factor exp ( - Δ E ¯ / ( k B T ) ) , which also determines the critical value of WFI between the strong-WFI and weak-WFI regimes.

  12. Method and apparatus for monitoring and measuring the surface tension of a fluid using fiber optics

    DOEpatents

    Abraham, Bernard M.; Ketterson, John B.; Bohanon, Thomas M.; Mikrut, John M.

    1994-01-01

    A non-contact method and apparatus for measuring and monitoring the surface of a fluid using fiber optics and interferometric detection to permit measurement mechanical characteristics' fluid surfaces. The apparatus employs an alternating electric field gradient for generating a capillary wave on the surface of the fluid. A fiber optic coupler and optical fiber directs a portion of a laser beam onto the surface of the fluid, another portion of the laser beam onto the photo sensor, and directs light reflected from the surface of the fluid onto the photo sensor. The output of the photo sensor is processed and coupled to a phase sensitive detector to permit measurement of phase shift between the drive signal creating the capillary wave and the detected signal. This phase shift information is then used to determine mechanical properties of the fluid surface such as surface tension, surface elasticity, and surface inhomogeneity. The resulting test structure is easily made compact, portable, and easy to align and use.

  13. Method and apparatus for monitoring and measuring the surface tension of a fluid using fiber optics

    DOEpatents

    Abraham, B.M.; Ketterson, J.B.; Bohanon, T.M.; Mikrut, J.M.

    1994-04-12

    A non-contact method and apparatus are described for measuring and monitoring the surface of a fluid using fiber optics and interferometric detection to permit measurement of mechanical characteristics of fluid surfaces. The apparatus employs an alternating electric field gradient for generating a capillary wave on the surface of the fluid. A fiber optic coupler and optical fiber directs a portion of a laser beam onto the surface of the fluid, another portion of the laser beam onto the photo sensor, and directs light reflected from the surface of the fluid onto the photo sensor. The output of the photo sensor is processed and coupled to a phase sensitive detector to permit measurement of phase shift between the drive signal creating the capillary wave and the detected signal. This phase shift information is then used to determine mechanical properties of the fluid surface such as surface tension, surface elasticity, and surface inhomogeneity. The resulting test structure is easily made compact, portable, and easy to align and use. 4 figures.

  14. Non-Newtonian fluid effects on surface reactions in a microfluidic flow cell

    NASA Astrophysics Data System (ADS)

    Akgül, M. Bahattin; Sarı, Gözde; Pakdemirli, Mehmet

    2012-11-01

    Mass transfer over a reactive surface in microfluidic flow cells plays a key role in understanding biomoleculer interactions and diagnosis of small molecules for biomedical and environmental applications. The effects of Non-Newtonian power law fluid on the binding reaction kinetic of immunoglobulin G in a flow cell are analyzed in this study. Governing equations for the fluid flow, mass transport and surface reaction are derived. The finite element method is employed to solve resulting equations. In addition, the effects of volumetric flow rate, fluid behavior index and reaction constants on the surface reaction are analyzed and presented graphically.

  15. Study of Surface Wave Propagation in Fluid-Saturated Porous Solids.

    NASA Astrophysics Data System (ADS)

    Azcuaga, Valery Francisco Godinez

    1995-01-01

    This study addresses the surface wave propagation phenomena on fluid-saturated porous solids. The analytical method for calculation of surface wave velocities (Feng and Johnson, JASA, 74, 906, 1983) is extended to the case of a porous solid saturated with a wetting fluid in contact with a non-wetting fluid, in order to study a material combination suitable for experimental investigation. The analytical method is further extended to the case of a non-wetting fluid/wetting fluid-saturated porous solid interface with an arbitrary finite surface stiffness. These extensions of the analytical method allows to theoretically study surface wave propagation phenomena during the saturation process. A modification to the 2-D space-time reflection Green's function (Feng and Johnson, JASA, 74, 915, 1983) is introduced in order to simulate the behavior of surface wave signals detected during the experimental investigation of surface wave propagation on fluid-saturated porous solids (Nagy, Appl. Phys. Lett., 60, 2735, 1992). This modification, together with the introduction of an excess attenuation for the Rayleigh surface mode, makes it possible to explain the apparent velocity changes observed on the surface wave signals during saturation. Experimental results concerning the propagation of surface waves on an alcohol-saturated porous glass are presented. These experiments were performed at frequencies of 500 and 800 kHz and show the simultaneous propagation of the two surface modes predicted by the extended analytical method. Finally an analysis of the displacements associated with the different surface modes is presented. This analysis reveals that it is possible to favor the generation of the Rayleigh surface mode or of the slow surface mode, simply by changing the type of transducer used in the generation of surface waves. Calculations show that a shear transducer couples more energy into the Rayleigh mode, whereas a longitudinal transducer couples more energy into the slow

  16. A new method for the determination of particulate contamination levels for surface cleanliness of fluid systems

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Levels of contamination in fluid systems can be determined by a definition of a particle by a mathematical model, a method for calculating the tolerance limits of contamination, and an estimation of the probability that the contamination on the surface will migrate with the fluid in the system.

  17. Airway Surface Dehydration by Transforming Growth Factor β (TGF-β) in Cystic Fibrosis Is Due to Decreased Function of a Voltage-dependent Potassium Channel and Can Be Rescued by the Drug Pirfenidone*

    PubMed Central

    Manzanares, Dahis; Krick, Stefanie; Baumlin, Nathalie; Dennis, John S.; Tyrrell, Jean; Tarran, Robert; Salathe, Matthias

    2015-01-01

    Transforming growth factor β1 (TGF-β1) is not only elevated in airways of cystic fibrosis (CF) patients, whose airways are characterized by abnormal ion transport and mucociliary clearance, but TGF-β1 is also associated with worse clinical outcomes. Effective mucociliary clearance depends on adequate airway hydration, governed by ion transport. Apically expressed, large-conductance, Ca2+- and voltage-dependent K+ (BK) channels play an important role in this process. In this study, TGF-β1 decreased airway surface liquid volume, ciliary beat frequency, and BK activity in fully differentiated CF bronchial epithelial cells by reducing mRNA expression of the BK γ subunit leucine-rich repeat-containing protein 26 (LRRC26) and its function. Although LRRC26 knockdown itself reduced BK activity, LRRC26 overexpression partially reversed TGF-β1-induced BK dysfunction. TGF-β1-induced airway surface liquid volume hyper-absorption was reversed by the BK opener mallotoxin and the clinically useful TGF-β signaling inhibitor pirfenidone. The latter increased BK activity via rescue of LRRC26. Therefore, we propose that TGF-β1-induced mucociliary dysfunction in CF airways is associated with BK inactivation related to a LRRC26 decrease and is amenable to treatment with clinically useful TGF-β1 inhibitors. PMID:26338706

  18. Stretching a Curved Surface in a Viscous Fluid

    NASA Astrophysics Data System (ADS)

    Sajid, M.; N., Ali; T., Javed; Z., Abbas

    2010-02-01

    This work is concerned with the viscous flow due to a curved stretching sheet. The similarity solution of the problem is obtained numerically by a shooting method using the Runge-Kutta algorithm. The physical quantities of interest like the fluid velocity and skin friction coefficient are obtained and discussed under the influence of dimensionless curvature. It is evident from the results that dimensionless curvature causes an increase in boundary layer thickness and a decrease in the skin friction coefficient.

  19. Wave turbulence in a two-layer fluid: Coupling between free surface and interface waves

    NASA Astrophysics Data System (ADS)

    Issenmann, Bruno; Laroche, Claude; Falcon, Eric

    2016-12-01

    We experimentally study gravity-capillary wave turbulence on the interface between two immiscible fluids of close density with free upper surface. We locally measure the wave height at the interface between both fluids by means of a highly sensitive laser Doppler vibrometer. We show that the inertial range of the capillary wave turbulence regime is significantly extended when the upper fluid depth is increased: The crossover frequency between the gravity and capillary wave turbulence regimes is found to decrease whereas the dissipative cut-off frequency of the spectrum is found to increase. We explain these observations by the progressive decoupling between waves propagating at the interface and the ones at the free surface, using the full dispersion relation of gravity-capillary waves in a two-layer fluid of finite depths. The cut-off evolution is due to the disappearance of parasitic capillaries responsible for the main wave dissipation for a single fluid.

  20. The Phillips airway.

    PubMed

    Haridas, R P; Wilkinson, D J

    2012-07-01

    The Phillips airway was developed by George Ramsay Phillips. There is no known original description of the airway and the earliest known reference to it is from 1919. The airway and its modifications are described.

  1. Interaction of Mycobacterium leprae with human airway epithelial cells: adherence, entry, survival, and identification of potential adhesins by surface proteome analysis.

    PubMed

    Silva, Carlos A M; Danelishvili, Lia; McNamara, Michael; Berredo-Pinho, Márcia; Bildfell, Robert; Biet, Franck; Rodrigues, Luciana S; Oliveira, Albanita V; Bermudez, Luiz E; Pessolani, Maria C V

    2013-07-01

    This study examined the in vitro interaction between Mycobacterium leprae, the causative agent of leprosy, and human alveolar and nasal epithelial cells, demonstrating that M. leprae can enter both cell types and that both are capable of sustaining bacterial survival. Moreover, delivery of M. leprae to the nasal septum of mice resulted in macrophage and epithelial cell infection in the lung tissue, sustaining the idea that the airways constitute an important M. leprae entry route into the human body. Since critical aspects in understanding the mechanisms of infection are the identification and characterization of the adhesins involved in pathogen-host cell interaction, the nude mouse-derived M. leprae cell surface-exposed proteome was studied to uncover potentially relevant adhesin candidates. A total of 279 cell surface-exposed proteins were identified based on selective biotinylation, streptavidin-affinity purification, and shotgun mass spectrometry; 11 of those proteins have been previously described as potential adhesins. In vitro assays with the recombinant forms of the histone-like protein (Hlp) and the heparin-binding hemagglutinin (HBHA), considered to be major mycobacterial adhesins, confirmed their capacity to promote bacterial attachment to epithelial cells. Taking our data together, they suggest that the airway epithelium may act as a reservoir and/or portal of entry for M. leprae in humans. Moreover, our report sheds light on the potentially critical adhesins involved in M. leprae-epithelial cell interaction that may be useful in designing more effective tools for leprosy control.

  2. Apoptosis and the Airway Epithelium

    PubMed Central

    White, Steven R.

    2011-01-01

    The airway epithelium functions as a barrier and front line of host defense in the lung. Apoptosis or programmed cell death can be elicited in the epithelium as a response to viral infection, exposure to allergen or to environmental toxins, or to drugs. While apoptosis can be induced via activation of death receptors on the cell surface or by disruption of mitochondrial polarity, epithelial cells compared to inflammatory cells are more resistant to apoptotic stimuli. This paper focuses on the response of airway epithelium to apoptosis in the normal state, apoptosis as a potential regulator of the number and types of epithelial cells in the airway, and the contribution of epithelial cell apoptosis in important airways diseases. PMID:22203854

  3. Dynamic, Hot Surface Ignition of Aircraft Fuels and Hydraulic Fluids

    DTIC Science & Technology

    1980-10-01

    alloys involved the formation of surface catalysts in the form of oxides of the parent metal, iron, nickel, and chromium , on the heated surfaces. Some...stainless steels and inconel X, the formed oxides or spinels (e.g. (FeO) 0 . 2 5 (Cr 2 03 ) 1 . 7 5 ) were quite stable and while protecting the heated

  4. Investigation of aluminum surface cleaning using cavitating fluid flow

    SciTech Connect

    Ralys, Aurimas; Striška, Vytautas; Mokšin, Vadim

    2013-12-16

    This paper investigates efficiency of specially designed atomizer used to spray water and cavitate microbubbles in water flow. Surface cleaning system was used to clean machined (grinded) aluminum surface from abrasive particles. It is established that cleaning efficiency depends on diameter of the diffuser, water pressure and distance between nozzle and metal surface. It is obtained that the best cleaning efficiency (100%) is achieved at pressure 36 bar, when diameter of diffuser is 0.4 mm and distance between nozzle and surface is 1 mm. It is also established that satisfactory cleaning efficiency (80%) is achieved not only when atomizer is placed closer to metal surface, but also at larger (120 mm) distances.

  5. Generating a Simulated Fluid Flow over a Surface Using Anisotropic Diffusion

    NASA Technical Reports Server (NTRS)

    Rodriguez, David L. (Inventor); Sturdza, Peter (Inventor)

    2016-01-01

    A fluid-flow simulation over a computer-generated surface is generated using a diffusion technique. The surface is comprised of a surface mesh of polygons. A boundary-layer fluid property is obtained for a subset of the polygons of the surface mesh. A gradient vector is determined for a selected polygon, the selected polygon belonging to the surface mesh but not one of the subset of polygons. A maximum and minimum diffusion rate is determined along directions determined using the gradient vector corresponding to the selected polygon. A diffusion-path vector is defined between a point in the selected polygon and a neighboring point in a neighboring polygon. An updated fluid property is determined for the selected polygon using a variable diffusion rate, the variable diffusion rate based on the minimum diffusion rate, maximum diffusion rate, and the gradient vector.

  6. Generating a Simulated Fluid Flow Over an Aircraft Surface Using Anisotropic Diffusion

    NASA Technical Reports Server (NTRS)

    Rodriguez, David L. (Inventor); Sturdza, Peter (Inventor)

    2013-01-01

    A fluid-flow simulation over a computer-generated aircraft surface is generated using a diffusion technique. The surface is comprised of a surface mesh of polygons. A boundary-layer fluid property is obtained for a subset of the polygons of the surface mesh. A pressure-gradient vector is determined for a selected polygon, the selected polygon belonging to the surface mesh but not one of the subset of polygons. A maximum and minimum diffusion rate is determined along directions determined using a pressure gradient vector corresponding to the selected polygon. A diffusion-path vector is defined between a point in the selected polygon and a neighboring point in a neighboring polygon. An updated fluid property is determined for the selected polygon using a variable diffusion rate, the variable diffusion rate based on the minimum diffusion rate, maximum diffusion rate, and angular difference between the diffusion-path vector and the pressure-gradient vector.

  7. Hard Surface Detergency. Part I. Interfacial Tensions of Candidate Surface Decontaminating Agents in Contact with Model Fluids.

    DTIC Science & Technology

    1982-04-23

    malathion . The effect of surfactant structure and model fluid on the adsorption process were catalogued with the aid of the Szyszkowski equation and the...the interfacial tension to low values by the surfactant when combined with the kinetic energy of the flow process assists in significant erosion of...methyl salicylate, malathion and ortho- dichlorobenzene. The interfacial tension properties of the fluids used are shown in Table 3. The surface tension

  8. Blockage of upper airway

    MedlinePlus

    ... Airway obstruction - acute upper Images Throat anatomy Choking Respiratory system References Cukor J, Manno M. Pediatric respiratory emergencies: upper airway obstruction and infections. In: Marx ...

  9. Convective Flow of Sisko Fluid over a Bidirectional Stretching Surface

    PubMed Central

    Munir, Asif; Shahzad, Azeem; Khan, Masood

    2015-01-01

    The present investigation focuses the flow and heat transfer characteristics of the steady three-dimensional Sisko fluid driven by a bidirectional stretching sheet. The modeled partial differential equations are reduced to coupled ordinary differential equations by a suitable transformation. The resulting equations are solved numerically by the shooting method using adaptive Runge Kutta algorithm in combination with Newton's method in the domain [0,∞). The numerical results for the velocity and temperature fields are graphically presented and effects of the relevant parameters are discussed in detail. Moreover, the skin-friction coefficient and local Nusselt number for different values of the power-law index and stretching ratio parameter are presented through tabulated data. The numerical results are also verified with the results obtained analytically by the homotopy analysis method (HAM). Additionally, the results are validated with previously published pertinent literature as a limiting case of the problem. PMID:26110873

  10. Convective Flow of Sisko Fluid over a Bidirectional Stretching Surface.

    PubMed

    Munir, Asif; Shahzad, Azeem; Khan, Masood

    2015-01-01

    The present investigation focuses the flow and heat transfer characteristics of the steady three-dimensional Sisko fluid driven by a bidirectional stretching sheet. The modeled partial differential equations are reduced to coupled ordinary differential equations by a suitable transformation. The resulting equations are solved numerically by the shooting method using adaptive Runge Kutta algorithm in combination with Newton's method in the domain [0,∞). The numerical results for the velocity and temperature fields are graphically presented and effects of the relevant parameters are discussed in detail. Moreover, the skin-friction coefficient and local Nusselt number for different values of the power-law index and stretching ratio parameter are presented through tabulated data. The numerical results are also verified with the results obtained analytically by the homotopy analysis method (HAM). Additionally, the results are validated with previously published pertinent literature as a limiting case of the problem.

  11. The capturing of free surfaces in incompressible multi-fluid flows

    NASA Astrophysics Data System (ADS)

    Pan, Dartzi; Chang, Chih-Hao

    2000-05-01

    By treating it as a contact discontinuity in the density field, a free surface between two immiscible fluids can be automatically captured by the enforcement of conservation laws. A surface-capturing method of this kind requires no special tracking or fitting treatment for the free surface, thereby offering the advantage of algorithm simplicity over the surface-tracking or the surface-fitting method. A surface-capturing method based on a new multi-fluid incompressible Navier-Stokes formulation is developed. It is applied to a variety of free-surface flows, including the Rayleigh-Taylor instability problem, the ship waves around a Wigley hull and a model bubble-rising problem to demonstrate the validity and versatility of the present method. Copyright

  12. Effect of the surface charge distribution on the fluid phase behavior of charged colloids and proteins

    NASA Astrophysics Data System (ADS)

    Blanco, Marco A.; Shen, Vincent K.

    2016-10-01

    A generic but simple model is presented to evaluate the effect of the heterogeneous surface charge distribution of proteins and zwitterionic nanoparticles on their thermodynamic phase behavior. By considering surface charges as continuous "patches," the rich set of surface patterns that is embedded in proteins and charged patchy particles can readily be described. This model is used to study the fluid phase separation of charged particles where the screening length is of the same order of magnitude as the particle size. In particular, two types of charged particles are studied: dipolar fluids and protein-like fluids. The former represents the simplest case of zwitterionic particles, whose charge distribution can be described by their dipole moment. The latter system corresponds to molecules/particles with complex surface charge arrangements such as those found in biomolecules. The results for both systems suggest a relation between the critical region, the strength of the interparticle interactions, and the arrangement of charged patches, where the critical temperature is strongly correlated to the magnitude of the dipole moment. Additionally, competition between attractive and repulsive charge-charge interactions seems to be related to the formation of fluctuating clusters in the dilute phase of dipolar fluids, as well as to the broadening of the binodal curve in protein-like fluids. Finally, a variety of self-assembled architectures are detected for dipolar fluids upon small changes to the charge distribution, providing the groundwork for studying the self-assembly of charged patchy particles.

  13. The Airway Microbiome at Birth

    PubMed Central

    Lal, Charitharth Vivek; Travers, Colm; Aghai, Zubair H.; Eipers, Peter; Jilling, Tamas; Halloran, Brian; Carlo, Waldemar A.; Keeley, Jordan; Rezonzew, Gabriel; Kumar, Ranjit; Morrow, Casey; Bhandari, Vineet; Ambalavanan, Namasivayam

    2016-01-01

    Alterations of pulmonary microbiome have been recognized in multiple respiratory disorders. It is critically important to ascertain if an airway microbiome exists at birth and if so, whether it is associated with subsequent lung disease. We found an established diverse and similar airway microbiome at birth in both preterm and term infants, which was more diverse and different from that of older preterm infants with established chronic lung disease (bronchopulmonary dysplasia). Consistent temporal dysbiotic changes in the airway microbiome were seen from birth to the development of bronchopulmonary dysplasia in extremely preterm infants. Genus Lactobacillus was decreased at birth in infants with chorioamnionitis and in preterm infants who subsequently went on to develop lung disease. Our results, taken together with previous literature indicating a placental and amniotic fluid microbiome, suggest fetal acquisition of an airway microbiome. We speculate that the early airway microbiome may prime the developing pulmonary immune system, and dysbiosis in its development may set the stage for subsequent lung disease. PMID:27488092

  14. Locomotion of microorganisms near a no-slip surface in a viscoelastic fluid

    NASA Astrophysics Data System (ADS)

    Yazdi, Shahrzad; Ardekani, Arezoo; Borhan, Ali

    2013-11-01

    Microorganisms are exposed to complex fluids in their natural habitats, especially during biological processes. In many of these processes, microorganisms swim in confined domains such as spermatozoa in mucus of mammalian reproduction tracts or bacteria in extracellular polymeric matrices during biofilm formation. Thus, it is important to understand the kinematics of propulsion in a viscolastic fluid near a no-slip surface. We used a squirmer model with a time-reversible body motion to analytically investigate the swimming kinematics in an Oldroyd-B fluid near a no-slip surface. Our results show that the time-averaged propulsion for a pusher (puller) is towards (away from) the no-slip surface. We present the swimming trajectory as a function of Deborah number, initial distance from the surface, and initial swimming direction.

  15. Ancient microbes from halite fluid inclusions: optimized surface sterilization and DNA extraction.

    PubMed

    Sankaranarayanan, Krithivasan; Timofeeff, Michael N; Spathis, Rita; Lowenstein, Tim K; Lum, J Koji

    2011-01-01

    Fluid inclusions in evaporite minerals (halite, gypsum, etc.) potentially preserve genetic records of microbial diversity and changing environmental conditions of Earth's hydrosphere for nearly one billion years. Here we describe a robust protocol for surface sterilization and retrieval of DNA from fluid inclusions in halite that, unlike previously published methods, guarantees removal of potentially contaminating surface-bound DNA. The protocol involves microscopic visualization of cell structures, deliberate surface contamination followed by surface sterilization with acid and bleach washes, and DNA extraction using Amicon centrifugal filters. Methods were verified on halite crystals of four different ages from Saline Valley, California (modern, 36 ka, 64 ka, and 150 ka), with retrieval of algal and archaeal DNA, and characterization of the algal community using ITS1 sequences. The protocol we developed opens up new avenues for study of ancient microbial ecosystems in fluid inclusions, understanding microbial evolution across geological time, and investigating the antiquity of life on earth and other parts of the solar system.

  16. Strongly coupled partitioned approach for fluid structure interaction in free surface flows

    NASA Astrophysics Data System (ADS)

    Facci, Andrea Luigi; Ubertini, Stefano

    2016-06-01

    In this paper we describe and validate a methodology for the numerical simulation of the fluid structure interaction in free surface flows. Specifically, this study concentrates on the vertical impact of a rigid body on the water surface, (i.e. on the hull slamming problem). The fluid flow is modeled through the volume of fluid methodology, and the structure dynamics is described by the Newton's second law. An iterative algorithm guarantees the tight coupling between the fluid and solid solvers, allowing the simulations of lightweight (i.e. buoyant) structures. The methodology is validated comparing numerical results to experimental data on the free fall of different rigid wedges. The correspondence between numerical results and independent experimental findings from literature evidences the reliability and the accuracy of the proposed approach.

  17. Drops settling in a fluid with surface tension increasing with depth

    NASA Astrophysics Data System (ADS)

    Shapiro, Avi; Blanchette, Francois

    2011-11-01

    We investigated numerically drops settling across layers of miscible fluids, representing oil droplets settling in a fluid stratified by temperature or salinity variations. The top layer is lighter than the lower one, while the drop itself is heavier than both layers. As the drop settles into the lower, its surface tension with the ambient fluid increases, which generates significant Marangoni effects. If the surface tension difference is small, the drop is delayed as it settles into the lower layer. Above a critical surface tension difference, the drop may be altogether prevented from crossing into the lower layer. We determine the conditions under which a drop may remain suspended at the transition region, and study the mixing generated by suspended drops. We acknowledge support from NSF grant DMS 0808129.

  18. Non-Newtonian fluid flow over a heterogeneously slippery surface

    NASA Astrophysics Data System (ADS)

    Haase, A. Sander; Wood, Jeffery A.; Sprakel, Lisette M. J.; Lammertink, Rob G. H.

    2015-11-01

    The no-slip boundary condition does not always hold. In the past, we have investigated the influence of effective wall slip on interfacial transport for a bubble mattress - a superhydrophobic surface consisting of an array of transverse gas-filled grooves. We proved experimentally that the amount of effective wall slip depends on the bubble protrusion angle and the surface porosity (Karatay et al., PNAS 110, 2013), and predicted that mass transport can be enhanced significantly (Haase et al., Soft Matter 9, 2013). Both studies involve the flow of water. In practise, however, many liquids encountered are non-Newtonian, like blood and polymer solutions. This raises some interesting questions. How does interfacial transport depend on the rheological properties of the liquid? Does the time-scale of the experiment matter? A bubble mattress is a suitable platform to investigate this, due to local variations in shear rate. We predict that for shear-thinning liquids, compared to water, the amount of wall slip can be enhanced considerably, although this depends on the applied flow rate. Experiments are performed to proof this behaviour. Simulations are used to assess what will happen when the characteristic time-scale of the system matches the relaxation time of the visco-elastic liquid. R.G.H.L. acknowledges the European Research Council for the ERC starting grant 307342-TRAM.

  19. Comparison of Simulated and Measured Fluid-Surface Oscillation Frequencies in a Channel

    NASA Astrophysics Data System (ADS)

    Trapuzzano, Matthew; Pierre, Kiesha; Tufekcioglu, Emre; Guldiken, Rasim; Tejada-Martinez, Andres; Crane, Nathan

    2016-11-01

    Many important processes from agriculture to manufacturing depend on the wetting of fluids on rough or textured surfaces. This has traditionally been studied from a macro-perspective. The effects of these surface features can be dramatically altered by vibrations that overcome energy barriers to contact line motion caused by surface roughness. In order to study these effects in confined geometries and at different length scales, a validated model is required. This presentation will compare the measured and simulated frequencies of capillary vibrations in a cylindrical glass tube. Fluid surface vibrations are excited externally through deformation of the interface. The resulting surface oscillations are observed with a high speed video camera and the dominant oscillation frequencies are calculated. The measured oscillation frequencies are compared to predictions from transient CFD simulations across a range of interface diameters from 400 um to 1.5 mm. These results may be used to inform studies of wetting under vibration. NSF CMMI-1361919.

  20. Fluid flow facilitates inward rectifier K+ current by convectively restoring [K+] at the cell membrane surface

    PubMed Central

    Kim, Jae Gon; Park, Sang Woong; Byun, Doyoung; Choi, Wahn Soo; Sung, Dong Jun; Shin, Kyung Chul; Kim, Hyun-ji; Leem, Young-Eun; Kang, Jong-Sun; Cho, Hana; Kim, Bokyung; Cho, Sung I; Bae, Young Min

    2016-01-01

    The inward rectifier Kir2.1 current (IKir2.1) was reported to be facilitated by fluid flow. However, the mechanism underlying this facilitation remains uncertain. We hypothesized that during K+ influx or efflux, [K+] adjacent to the outer mouth of the Kir2.1 channel might decrease or increase, respectively, compared with the average [K+] of the bulk extracellular solution, and that fluid flow could restore the original [K+] and result in the apparent facilitation of IKir2.1. We recorded the IKir2.1 in RBL-2H3 cells and HEK293T cells that were ectopically over-expressed with Kir2.1 channels by using the whole-cell patch-clamp technique. Fluid-flow application immediately increased the IKir2.1, which was not prevented by either the pretreatment with inhibitors of various protein kinases or the modulation of the cytoskeleton and caveolae. The magnitudes of the increases of IKir2.1 by fluid flow were driving force-dependent. Simulations performed using the Nernst-Planck mass equation indicated that [K+] near the membrane surface fell markedly below the average [K+] of the bulk extracellular solution during K+ influx, and, notably, that fluid flow restored the decreased [K+] at the cell surface in a flow rate-dependent manner. These results support the “convection-regulation hypothesis” and define a novel interpretation of fluid flow-induced modulation of ion channels. PMID:28004830

  1. Fluid flow facilitates inward rectifier K(+) current by convectively restoring [K(+)] at the cell membrane surface.

    PubMed

    Kim, Jae Gon; Park, Sang Woong; Byun, Doyoung; Choi, Wahn Soo; Sung, Dong Jun; Shin, Kyung Chul; Kim, Hyun-Ji; Leem, Young-Eun; Kang, Jong-Sun; Cho, Hana; Kim, Bokyung; Cho, Sung I; Bae, Young Min

    2016-12-22

    The inward rectifier Kir2.1 current (IKir2.1) was reported to be facilitated by fluid flow. However, the mechanism underlying this facilitation remains uncertain. We hypothesized that during K(+) influx or efflux, [K(+)] adjacent to the outer mouth of the Kir2.1 channel might decrease or increase, respectively, compared with the average [K(+)] of the bulk extracellular solution, and that fluid flow could restore the original [K(+)] and result in the apparent facilitation of IKir2.1. We recorded the IKir2.1 in RBL-2H3 cells and HEK293T cells that were ectopically over-expressed with Kir2.1 channels by using the whole-cell patch-clamp technique. Fluid-flow application immediately increased the IKir2.1, which was not prevented by either the pretreatment with inhibitors of various protein kinases or the modulation of the cytoskeleton and caveolae. The magnitudes of the increases of IKir2.1 by fluid flow were driving force-dependent. Simulations performed using the Nernst-Planck mass equation indicated that [K(+)] near the membrane surface fell markedly below the average [K(+)] of the bulk extracellular solution during K(+) influx, and, notably, that fluid flow restored the decreased [K(+)] at the cell surface in a flow rate-dependent manner. These results support the "convection-regulation hypothesis" and define a novel interpretation of fluid flow-induced modulation of ion channels.

  2. Analysis of matching conditions at the boundary surface of a fluid-saturated porous solid and a bulk fluid: the use of Lagrange multipliers

    NASA Astrophysics Data System (ADS)

    Kubik, J.; Cieszko, M.

    2005-12-01

    The compatibility conditions matching macroscopic mechanical fields at the contact surface between a fluid-saturated porous solid and an adjacent bulk fluid are considered. The general form of balance equations at that discontinuity surface are analyzed to obtain the compatibility conditions for the tangent and normal components of the velocity and the stress vector fields. Considerations are based on the procedure similar to that used in the phenomenological thermodynamics for derivation of constitutive relations, where the entropy inequality and the concept of Lagrange multipliers are applied. This procedure made possible to derive the compatibility conditions for the viscous fluid flowing tangentially and perpendicularly to the boundary surface of the porous solid and to formulate the generalized form of the so called slip condition for the fluid velocity field, postulated earlier by Beavers and Joseph, J. Fluid. Mech. 30, 197-207 (1967).

  3. Monitoring of Surface Grinding process using Acoustic Emission (AE) with emphasis on Cutting Fluid selection

    NASA Astrophysics Data System (ADS)

    Nisal, Tejas V.

    Correct selection of cutting fluid is an important step in all machining operations. In this study, experiments were designed and conducted on AISI 52100 steel to determine the effects of using different cutting fluids in Surface Grinding. The grinding parameters varied were wheel speed, feed, depth of cut and type of cutting fluid. The grinding responses studied here were Acoustic Emission (AE) Signals, Normal and Tangential Forces on the workpiece surface, Grinding Temperature and Surface Roughness. Potential of Acoustic Emission technique as a tool to provide efficient real-time knowledge and monitoring of the grinding process, is tested in this research. AERMS values were used to analyses the process characteristics. This paper proposes four different statistical models for predicting Grinding Temperature, Force, Acoustic Emission (AERMS) and Roughness, based on grinding parameters. This research concludes that the selection of Cutting Fluids influence the Surface finish, AE signals, Temperature and grinding Forces measured. Further, prediction of surface roughness during the grinding process using AE signal monitoring is demonstrated in this work.

  4. Macroscopic surface tension in a lattice Bhatnagar-Gross-Krook model of two immiscible fluids

    NASA Astrophysics Data System (ADS)

    Halliday, I.; Thompson, S. P.; Care, C. M.

    1998-01-01

    We present a method by which an interface generating algorithm, similar to that of earlier lattice Boltzmann models of immiscible fluids, may be extended to a two component, two-speed two-dimensional (D2), nine-link (Q9) lattice Bhatnagar-Gross-Krook fluid. For two-dimensional, microcurrent-free planar interfaces between the two immiscible fluids we derive expressions for static interfacial tensions and interfacial distributions of the two fluids. Extending our analysis to curved interfaces, we propose a scheme for incorporating the influence of interfacial microcurrents that is based upon general symmetry arguments and is correct to second order in lattice velocity. The analysis demonstrates that the interfacial microcurrents have only second-order influence upon the macroscopic behavior of the model. We find good agreement between our calculations and simulation results based on the microcurrent stream function and surface tension results from the pressure tensor or Laplace law.

  5. Macroscopic Surface Tension in a Lattice Boltzmann BGK Model of Two Immiscible Fluids.

    NASA Astrophysics Data System (ADS)

    Thompson, S. P.; Halliday, I.; Care, C. M.

    1997-08-01

    We present a method by which an interface generating algorithm, similar to that of earlier lattice Boltzmann models of immisible fluids, may be extended to a two component, two-speed D2Q9 lattice Bhatnagar Gross Krook fluid. For two-dimensional, microcurrent-free planar interfaces between the two immiscible fluids we derive expressions for static interfacial tensions and interfacial distributions of the two fluids. Extending our analysis to curved interfaces we propose a scheme for incorporating the influence of interfacial microcurrents which is based upon general symmetry arguments and is correct to second order in lattice velocity. The analysis demonstrates that the interfacial microcurrents have only second order influence upon the macroscopic behaviour of the model. We find good agreement between our calculations and simulation results based on the microcurrent stream function and surface tension results from the pressure tensor or Laplace law.

  6. Nonorthogonal Stagnation-point Flow of a Second-grade Fluid Past a Lubricated Surface

    NASA Astrophysics Data System (ADS)

    Mahmood, Khalid; Sajid, Muhammad; Ali, Nasir

    2016-03-01

    The stagnation-point flow of a second-grade fluid past a power law lubricated surface is considered in this paper. It is assumed that the fluid impinges on the wall obliquely. A suitable choice of similarity transformations reduces the governing partial differential equations into ordinary differential equations. The thin lubrication layer suggests that the interface conditions between the fluid and the lubricant can be imposed on the boundary. An implicit finite difference scheme known as the Keller-Box method is employed to obtain the numerical solutions. The effects of slip parameter and Weissenberg number on the fluid velocity and streamlines is discussed in the graphs. The limiting cases of partial-slip and no-slip can be deduced from the present solutions.

  7. Triggers of airway inflammation.

    PubMed

    Kerrebijn, K F

    1986-01-01

    Most asthmatics have hyperresponsive airways. This makes them more sensitive than non-asthmatics to bronchoconstricting environmental exposures which, in their turn, may enhance responsiveness. Airway inflammation is considered to be a key determinant of airway hyperresponsiveness: the fact that chronic airway inflammation in cystic fibrosis does not lead to airway hyperresponsiveness of any importance indicates, however, that the role of airway inflammation is complex and incompletely elucidated. The main inducers of airway inflammation are viral infections, antigens, occupational stimuli and pollutants. Although exercise, airway cooling and hyper- or hypotonic aerosols are potent stimuli of bronchoconstriction, it is questionable if airway inflammation is involved in their mode of action. Each of the above-mentioned stimuli is discussed, with emphasis laid on the relation of symptoms to mechanisms.

  8. Broadband cylindrical acoustic cloak for linear surface waves in a fluid.

    PubMed

    Farhat, M; Enoch, S; Guenneau, S; Movchan, A B

    2008-09-26

    We describe the first practical realization of a cylindrical cloak for linear surface liquid waves. This structured metamaterial bends surface waves radiated by a closely located acoustic source over a finite interval of Hertz frequencies. We demonstrate theoretically its unique mechanism using homogenization theory: the cloak behaves as an effective anisotropic fluid characterized by a diagonal stress tensor in a cylindrical basis. A low azimuthal viscosity is achieved, where the fluid flows most rapidly. Numerical simulations demonstrate that the homogenized cloak behaves like the actual structured cloak. We experimentally analyze the decreased backscattering of a fluid with low viscosity and finite density (methoxynonafluorobutane) from a cylindrical rigid obstacle surrounded by the cloak when it is located a couple of wavelengths away from the acoustic source.

  9. Dropwise Condensation of Low Surface Tension Fluids on iCVD Grafted Polymer Films

    NASA Astrophysics Data System (ADS)

    Khalil, Karim; Gleason, Karen; Varanasi, Kripa

    2016-11-01

    A large majority of the work devoted to surface engineering for promoting dropwise condensation heat transfer has focused on steam. Much less attention has been dedicated to the condensation of low surface tension fluids such as hydrocarbons, cryogens, and fluorinated refrigerants, which are used in several industrial applications, including LNG storage and organic Rankine cycles used for heat recovery from low temperature sources such as biomass combustion, industrial waste, or geothermal heat sources. Most hydrophobic modifiers used previously to promote dropwise condensation are silane-based monolayers that have been shown to rapidly degrade under industrial conditions. Here we investigate condensation behavior of a variety of low surface tension liquids on durable covalently-grafted polymer films deposited using initiated chemical vapor deposition (iCVD) on metals such as titanium. We observe a four to seven-fold improvement in the vapor-side heat transfer coefficient by promoting dropwise condensation of low surface tension fluids on these stable films.

  10. Surface water paleotemperatures and chemical compositions from fluid inclusions in Permian Nippewalla Group halite

    SciTech Connect

    Benison, K.C.

    1996-12-31

    Quantitative climatic data for the Permian have been determined from Nippewalla Group halite. The middle Permian Nippewalla Group of Kansas and Oklahoma consists of several hundred feet of bedded halite, anhydrite, and red beds. Study of core and surface samples suggest that this halite was deposited by ephemeral lakes. Fluid inclusions provide evidence for the geochemistry of these Permian saline lake waters, including temperatures, salinities, and chemical compositions. Primary fluid inclusions are well-preserved in the Nippewalla halite. They are 5 - 30 {mu}m cubic inclusions situated along chevron and cornet growth bands. Most are one phase aqueous inclusions, but some also contain anhydride {open_quote}accidental{close_quotes} crystals. Rare two phase liquid-vapor inclusions may have formed by subaqueous outgassing or trapping of air at the water surface. Fluid inclusion freezing-melting behavior and leachate analyses suggest that Nippewalla halite precipitated from Na-Cl-rich waters with lesser quantities of SO{sub 4}, Mg, K, Al, and Si. This composition may be a product of long-term weathering. Surface water paleotemperatures were determined from one phase aqueous fluid inclusions. Homogenization temperatures range from 32 to 46{degrees}C in primary fluid inclusions and are consistent (within 3{degrees}C) along individual chevrons and cornets. These homogenization temperatures are interpreted to represent maximum surface water temperatures. These fluid inclusion data are significant in addressing global change problems. Temperatures and chemistries in these Permian lake waters agree with some modern shallow saline lake waters and with Permian climate models. This study suggests that this Permian environment was relatively similar to its modern counterparts.

  11. Surface water paleotemperatures and chemical compositions from fluid inclusions in Permian Nippewalla Group halite

    SciTech Connect

    Benison, K.C. )

    1996-01-01

    Quantitative climatic data for the Permian have been determined from Nippewalla Group halite. The middle Permian Nippewalla Group of Kansas and Oklahoma consists of several hundred feet of bedded halite, anhydrite, and red beds. Study of core and surface samples suggest that this halite was deposited by ephemeral lakes. Fluid inclusions provide evidence for the geochemistry of these Permian saline lake waters, including temperatures, salinities, and chemical compositions. Primary fluid inclusions are well-preserved in the Nippewalla halite. They are 5 - 30 [mu]m cubic inclusions situated along chevron and cornet growth bands. Most are one phase aqueous inclusions, but some also contain anhydride [open quote]accidental[close quotes] crystals. Rare two phase liquid-vapor inclusions may have formed by subaqueous outgassing or trapping of air at the water surface. Fluid inclusion freezing-melting behavior and leachate analyses suggest that Nippewalla halite precipitated from Na-Cl-rich waters with lesser quantities of SO[sub 4], Mg, K, Al, and Si. This composition may be a product of long-term weathering. Surface water paleotemperatures were determined from one phase aqueous fluid inclusions. Homogenization temperatures range from 32 to 46[degrees]C in primary fluid inclusions and are consistent (within 3[degrees]C) along individual chevrons and cornets. These homogenization temperatures are interpreted to represent maximum surface water temperatures. These fluid inclusion data are significant in addressing global change problems. Temperatures and chemistries in these Permian lake waters agree with some modern shallow saline lake waters and with Permian climate models. This study suggests that this Permian environment was relatively similar to its modern counterparts.

  12. Fluid dynamics and noise in bacterial cell–cell and cell–surface scattering

    PubMed Central

    Drescher, Knut; Dunkel, Jörn; Cisneros, Luis H.; Ganguly, Sujoy; Goldstein, Raymond E.

    2011-01-01

    Bacterial processes ranging from gene expression to motility and biofilm formation are constantly challenged by internal and external noise. While the importance of stochastic fluctuations has been appreciated for chemotaxis, it is currently believed that deterministic long-range fluid dynamical effects govern cell–cell and cell–surface scattering—the elementary events that lead to swarming and collective swimming in active suspensions and to the formation of biofilms. Here, we report direct measurements of the bacterial flow field generated by individual swimming Escherichia coli both far from and near to a solid surface. These experiments allowed us to examine the relative importance of fluid dynamics and rotational diffusion for bacteria. For cell–cell interactions it is shown that thermal and intrinsic stochasticity drown the effects of long-range fluid dynamics, implying that physical interactions between bacteria are determined by steric collisions and near-field lubrication forces. This dominance of short-range forces closely links collective motion in bacterial suspensions to self-organization in driven granular systems, assemblages of biofilaments, and animal flocks. For the scattering of bacteria with surfaces, long-range fluid dynamical interactions are also shown to be negligible before collisions; however, once the bacterium swims along the surface within a few microns after an aligning collision, hydrodynamic effects can contribute to the experimentally observed, long residence times. Because these results are based on purely mechanical properties, they apply to a wide range of microorganisms. PMID:21690349

  13. Low gravity experiment for studying a rotating fluid having a free surface

    NASA Technical Reports Server (NTRS)

    Holderer, O. C.

    1983-01-01

    Electrical, mechanical, and operational aspects of a test cell assembly for studying rotating fluids with a free surface are described. Results of a stress analysis prepared to document the structural adequacy for safe use on the KC-135 aircraft are presented along with results of a single load proof test of the most critical load case. Engineering drawings are included.

  14. An uptake of cationized ferritin by alveolar type I cells in airway-instilled goat lung: distribution of anionic sites on the epithelial surface.

    PubMed

    Atwal, O S; Viel, L; Minhas, K J

    1990-07-01

    The present study has investigated ultrastructural localization of anionic sites on the luminal surface of the alveolar epithelium of goat lung by direct airway instillation of cationized ferritin (CF) in the cranial lobe of the right lung through a bronchoscope. The cationic probe decorated preferentially the luminal plasmalemmal vesicles and plasmalemma proper of alveolar type I cell. This indicated the presence of highly charged anionic microdomains at these binding sites. The ligand was internalized in the free plasmalemmal vesicles of alveolar type I cell within 2 min. Heavy decoration of vesicles at 5 min of perfusion indicated that the amount of CF internalization increased with its concentration in the alveoli. It is suggested that exposure of alveolar surface to several gases of ruminal-origin induces changes in the surface charge of luminal plasmalemma of alveolar type I cells. The significance of these anionic plasmalemmal sites is discussed in relation to the adjustment of osmotic pressure gradient across the alveolar-capillary membrane of the ruminant lung.

  15. Upregulation and activation of eosinophil integrins in blood and airway after segmental lung antigen challenge1

    PubMed Central

    Johansson, Mats W.; Kelly, Elizabeth A. B.; Busse, William W.; Jarjour, Nizar N.; Mosher, Deane F.

    2008-01-01

    We hypothesized that there are clinically relevant differences in eosinophil integrin expression and activation in patients with asthma. To evaluate this, surface densities and activation states of integrins on eosinophils in blood and bronchoalveolar lavage (BAL) of 19 asthmatic subjects were studied before and 48 h after segmental Ag challenge. At 48 h, there was increased expression of αD and the N29 epitope of activated β1 integrins on blood eosinophils and of αM, β2, and the mAb24 epitope of activated β2 integrins on airway eosinophils. Changes correlated with the late-phase fall in forced expiratory volume in 1 s (FEV1) after whole-lung inhalation of the Ag that was subsequently used in segmental challenge and were greater in subjects defined as dual responders. Increased surface densities of αM and β2 and activation of β2 on airway eosinophils correlated with the concentration of IL-5 in BAL fluid. Activation of β1 and β2 on airway eosinophils correlated with eosinophil percentage in BAL. Thus, eosinophils respond to an allergic stimulus by activation of integrins in a sequence that likely promotes eosinophilic inflammation of the airway. Before challenge, β1 and β2 integrins of circulating eosinophils are in low-activation conformations, and αDβ2 surface expression is low. After Ag challenge, circulating eosinophils adopt a phenotype with activated β1 integrins and upregulated αDβ2, changes that are predicted to facilitate eosinophil arrest on VCAM-1 in bronchial vessels. Finally, eosinophils present in IL-5-rich airway fluid have a hyperadhesive phenotype associated with increased surface expression of αMβ2 and activation of β2 integrins. PMID:18490765

  16. Surface tension of the two center Lennard-Jones plus point dipole fluid.

    PubMed

    Werth, Stephan; Horsch, Martin; Hasse, Hans

    2016-02-07

    Molecular dynamics simulations are used for systematically studying the surface tension of the two center Lennard-Jones plus point dipole (2CLJD) model fluid. In a dimensionless representation, this model fluid has two parameters describing the elongation and the dipole moment. These parameters were varied in the entire range relevant for describing real fluids resulting in a grid of 38 individual models. For each model, the surface tension was determined at temperatures between 60% and 90% of the critical temperature. For completeness, the vapor pressure and the saturated densities were also determined. The latter results agree well with the literature data, whereas for the surface tension, only few data were previously available. From the present results, an empirical correlation for the surface tension of the 2CLJD model as a function of the model parameters is developed. The correlation is used to predict the surface tension of 46 2CLJD molecular models from the literature, which were adjusted to bulk properties, but not to interfacial properties. The results are compared to the experimental data. The molecular models overestimate the surface tension, and deviations between the predictions and experimental data are below 12% on average.

  17. Enhanced slippery behavior and stability of lubricating fluid infused nanostructured surfaces

    NASA Astrophysics Data System (ADS)

    Pant, Reeta; Ujjain, Sanjeev Kumar; Nagarajan, Arun Kumar; Khare, Krishnacharya

    2016-07-01

    Stability of lubricating fluid infused slippery surfaces is a concern for scientists and engineers and attempts are being made for its improvement. Lubricating oil coated slippery surface for aqueous drops is one of the important candidates in this class and their stability needs be improved to make them useful for practical applications. Cloaking of water drops with thin lubricant layer results in the loss of lubricant leading to deterioration of slippery behavior. Surface roughness or porosity provides larger surface area to the lubricating fluid and would to affect the stability of the lubricating film. Here we report the effect of surface roughness, from tens of nanometer to few microns, on the stability of slippery surface. Samples with small nanoscale roughness show improved performance in terms of contact angle hysteresis, critical tilt angle and slip velocity. Whereas large roughness samples show poorer performance compared to small nanoscale roughness and smooth samples. Small nanoscale roughness samples also show relatively slower deterioration against loss of lubricant during water flow. Once completely lost, the slippery behavior can be restored again simply by coating the sample again by the lubricating fluid.

  18. Surface contouring by controlled application of processing fluid using Marangoni effect

    DOEpatents

    Rushford, Michael C.; Britten, Jerald A.

    2003-04-29

    An apparatus and method for modifying the surface of an object by contacting said surface with a liquid processing solution using the liquid applicator geometry and Marangoni effect (surface tension gradient-driven flow) to define and confine the dimensions of the wetted zone on said object surface. In particular, the method and apparatus involve contouring or figuring the surface of an object using an etchant solution as the wetting fluid and using realtime metrology (e.g. interferometry) to control the placement and dwell time of this wetted zone locally on the surface of said object, thereby removing material from the surface of the object in a controlled manner. One demonstrated manifestation is in the deterministic optical figuring of thin glasses by wet chemical etching using a buffered hydrofluoric acid solution and Marangoni effect.

  19. Pathway from subducting slab to surface for melt and fluids beneath Mount Rainier.

    PubMed

    McGary, R Shane; Evans, Rob L; Wannamaker, Philip E; Elsenbeck, Jimmy; Rondenay, Stéphane

    2014-07-17

    Convergent margin volcanism originates with partial melting, primarily of the upper mantle, into which the subducting slab descends. Melting of this material can occur in one of two ways. The flow induced in the mantle by the slab can result in upwelling and melting through adiabatic decompression. Alternatively, fluids released from the descending slab through dehydration reactions can migrate into the hot mantle wedge, inducing melting by lowering the solidus temperature. The two mechanisms are not mutually exclusive. In either case, the buoyant melts make their way towards the surface to reside in the crust or to be extruded as lava. Here we use magnetotelluric data collected across the central state of Washington, USA, to image the complete pathway for the fluid-melt phase. By incorporating constraints from a collocated seismic study into the magnetotelluric inversion process, we obtain superior constraints on the fluids and melt in a subduction setting. Specifically, we are able to identify and connect fluid release at or near the top of the slab, migration of fluids into the overlying mantle wedge, melting in the wedge, and transport of the melt/fluid phase to a reservoir in the crust beneath Mt Rainier.

  20. Pathway from subducting slab to surface for melt and fluids beneath Mount Rainier

    NASA Astrophysics Data System (ADS)

    McGary, R. Shane; Evans, Rob L.; Wannamaker, Philip E.; Elsenbeck, Jimmy; Rondenay, Stéphane

    2014-07-01

    Convergent margin volcanism originates with partial melting, primarily of the upper mantle, into which the subducting slab descends. Melting of this material can occur in one of two ways. The flow induced in the mantle by the slab can result in upwelling and melting through adiabatic decompression. Alternatively, fluids released from the descending slab through dehydration reactions can migrate into the hot mantle wedge, inducing melting by lowering the solidus temperature. The two mechanisms are not mutually exclusive. In either case, the buoyant melts make their way towards the surface to reside in the crust or to be extruded as lava. Here we use magnetotelluric data collected across the central state of Washington, USA, to image the complete pathway for the fluid-melt phase. By incorporating constraints from a collocated seismic study into the magnetotelluric inversion process, we obtain superior constraints on the fluids and melt in a subduction setting. Specifically, we are able to identify and connect fluid release at or near the top of the slab, migration of fluids into the overlying mantle wedge, melting in the wedge, and transport of the melt/fluid phase to a reservoir in the crust beneath Mt Rainier.

  1. Emergency airway puncture

    MedlinePlus

    ... support for only a very short period of time. Alternative Names Needle cricothyrotomy Images Emergency airway puncture Cricoid cartilage Emergency airway puncture - series References Hebert RB, Bose S, Mace SE. Cricothyrotomy and ...

  2. Upper airway biopsy

    MedlinePlus

    ... upper airway Images Upper airway test Bronchoscopy Throat anatomy References Yung RC, Boss EF. Tracheobronchial endoscopy. In: Flint PW, Haughey BH, Lund LJ, et al, eds. Cummings Otolaryngology: Head & Neck Surgery. 5th ed. Philadelphia, PA: Elsevier Mosby; ...

  3. 3-D Maxwell fluid flow over an exponentially stretching surface using 3-stage Lobatto IIIA formula

    NASA Astrophysics Data System (ADS)

    Awais, M.; Hayat, T.; Ali, Aamir

    2016-05-01

    The present study looks at the three dimensional boundary layer flow driven by an exponentially stretching surface. An upper-convected Maxwell (UCM) fluid is considered. Characteristics here are characterized by rheological constitutive equations of upper convected Maxwell (UCM) fluid. Involved mathematical modeling constitutes a nonlinear differential system. 3-stage Lobatto IIIA formula is employed to construct the numerical solutions whereas analytic solutions are computed using HAM. Both solutions are compared and found in good agreement. The velocity components are analyzed for the Deborah number and ratio parameters.

  4. Secretion of acid and base equivalents by intact distal airways.

    PubMed

    Inglis, S K; Wilson, S M; Olver, R E

    2003-05-01

    Secretion of HCO(3)(-) by airway submucosal glands is essential for normal liquid and mucus secretion. Because the liquid bathing the airway surface (ASL) is acidic, it has been proposed that the surface epithelium may acidify HCO(3)(-)-rich glandular fluid. The aim of this study was to investigate the mechanisms by which intact distal bronchi, which contain both surface and glandular epithelium, modify pH of luminal fluid. Distal bronchi were isolated from pig lungs, cannulated in a bath containing HCO(3)(-)-buffered solution, and perfused continually with an aliquot of similar, lightly buffered solution (LBS) in which NaCl replaced NaHCO(3)(-) (pH 7 with NaOH). The pH of this circulating LBS initially acidified (by 0.053 +/- 0.0053 pH units) and transepithelial potential difference (PD) depolarized. The magnitude of acidification was increased when pH(LBS) was higher. This acidification was unaffected by luminal dimethylamiloride (DMA, 100 microM) but was inhibited by 100 nM bafilomycin A(1) (by 76 +/- 13%), suggesting involvement of vacuolar-H(+) ATPase. Addition of ACh (10 microM) evoked alkalinization of luminal LBS and hyperpolarization of transepithelial PD. The alkalinization was inhibited in HCO(3)(-)-free solutions containing acetazolamide (1 mM) and by DMA and was enhanced by bumetanide (100 microM), an inhibitor of Cl(-) secretion. The hyperpolarization was unaffected by these maneuvers. The anion channel blocker 5-nitro-2-(3-phenylpropylamino)benzoate (300 microM) and combined treatment with DMA and bumetanide blocked both the alkalinization and hyperpolarization responses to ACh. These results are consistent with earlier studies showing that ACh evokes glandular secretion of HCO(3)(-) and Cl(-). Isolated distal airways thus secrete both acid and base equivalents.

  5. Surface energetics of freely suspended fluid molecular monolayer and multilayer smectic liquid crystal films

    PubMed Central

    Nguyen, Zoom Hoang; Park, Cheol Soo; Pang, Jinzhong; Clark, Noel A.

    2012-01-01

    A study of the surface energetics of the thinnest substrate-free liquid films, fluid molecular monolayer and multilayer smectic liquid crystal films suspended in air, is reported. In films having monolayer and multilayer domains, the monolayer areas contract, contrary to predictions from the van der Waals disjoining pressure of thin uniform slabs. This discrepancy is accounted for by modeling the environmental asymmetry of the surface layers in multilayer films, leading to the possibility that preferential end-for-end polar ordering of the rod shaped molecules can reduce the surface energy of multilayers relative to that of the monolayer, which is inherently symmetric. PMID:22826264

  6. Transient Thermal Model and Analysis of the Lunar Surface and Regolith for Cryogenic Fluid Storage

    NASA Technical Reports Server (NTRS)

    Christie, Robert J.; Plachta, David W.; Yasan, Mohammad M.

    2008-01-01

    A transient thermal model of the lunar surface and regolith was developed along with analytical techniques which will be used to evaluate the storage of cryogenic fluids at equatorial and polar landing sites. The model can provide lunar surface and subsurface temperatures as a function of latitude and time throughout the lunar cycle and season. It also accounts for the presence of or lack of the undisturbed fluff layer on the lunar surface. The model was validated with Apollo 15 and Clementine data and shows good agreement with other analytical models.

  7. Careers in Airway Science.

    ERIC Educational Resources Information Center

    Federal Aviation Administration (DOT), Washington, DC.

    The Federal Aviation Administration (FAA) has initiated the Airway Science curriculum as a method of preparing the next generation of aviation technicians and managers. This document: (1) discusses the FAA's role in the Airway Science program; (2) describes some of the career fields that FAA offers to Airway Science graduates (air traffic control…

  8. Theory of Wetting-Induced Fluid Entrainment by Advancing Contact Lines on Dry Surfaces

    NASA Astrophysics Data System (ADS)

    Ledesma-Aguilar, R.; Hernández-Machado, A.; Pagonabarraga, I.

    2013-06-01

    We report on the onset of fluid entrainment when a contact line is forced to advance over a dry solid of arbitrary wettability. We show that entrainment occurs at a critical advancing speed beyond which the balance between capillary, viscous, and contact-line forces sustaining the shape of the interface is no longer satisfied. Wetting couples to the hydrodynamics by setting both the morphology of the interface at small scales and the viscous friction of the front. We find that the critical deformation that the interface can sustain is controlled by the friction at the contact line and the viscosity contrast between the displacing and displaced fluids, leading to a rich variety of wetting-entrainment regimes. We discuss the potential use of our theory to measure contact-line forces using atomic force microscopy and to study entrainment under microfluidic conditions exploiting colloid-polymer fluids of ultralow surface tension.

  9. Theory of wetting-induced fluid entrainment by advancing contact lines on dry surfaces.

    PubMed

    Ledesma-Aguilar, R; Hernández-Machado, A; Pagonabarraga, I

    2013-06-28

    We report on the onset of fluid entrainment when a contact line is forced to advance over a dry solid of arbitrary wettability. We show that entrainment occurs at a critical advancing speed beyond which the balance between capillary, viscous, and contact-line forces sustaining the shape of the interface is no longer satisfied. Wetting couples to the hydrodynamics by setting both the morphology of the interface at small scales and the viscous friction of the front. We find that the critical deformation that the interface can sustain is controlled by the friction at the contact line and the viscosity contrast between the displacing and displaced fluids, leading to a rich variety of wetting-entrainment regimes. We discuss the potential use of our theory to measure contact-line forces using atomic force microscopy and to study entrainment under microfluidic conditions exploiting colloid-polymer fluids of ultralow surface tension.

  10. Saturated pool-boiling heat transfer of toluene-solvent magnetic fluid on a horizontal surface

    SciTech Connect

    Takahashi, Minoru; Inoue, Akiro; Matsuzaki, Mitsuo; Ohkawa, Riichiro . Research Lab. for Nuclear Reactors)

    1994-07-01

    Saturated pool-boiling heat transfer of a toluene-solvent magnetic fluid containing magnetite particles of 0--36.5 wt% was investigated on a horizontal surface in a vertical magnetic field at pressures of 0.021--0.061 MPa. In the absence of a magnetic field gradient, the heat transfer was enhanced significantly using a magnetic fluid with dilute magnetite particles, while it was reduced for the case of dense particles. As the magnetic field gradient was increased up to 3.9 [times] 10[sup 5] A/m[sup 2], the heat transfer of the dense magnetic fluid was enhanced significantly in the heat flux region, although it slowly began to show a reduced heat-transfer curve again at a certain transition heat flux. The transition heat flux increased as the magnetic field gradient became larger, the magnetic concentration, lower, and the pressure, higher.

  11. The Effect of Surface Roughness on Fluid Configuration and Solute Transport in Unsaturated Porous Media

    NASA Astrophysics Data System (ADS)

    Kibbey, T. C.

    2013-12-01

    When describing the configuration of water in unsaturated media, a distinction is often made between water that is held by capillary forces between grains (capillary water), and water associated with adsorbed films on solid surfaces (film water). The objective of this work was to better understand the nature of the water associated with solid surfaces, with emphasis on understanding the configuration of water on rough natural surfaces. Stereoscopic SEM was used to determine elevation maps on a range of different natural solid surfaces. A computational technique was then developed to calculate the configuration of water on the surfaces as a function of capillary pressure. Calculations of fluid configurations show that, except at extremely high capillary pressures, fluid configuration is dominated by bridging of surface roughness features, even for extremely smooth surfaces. Results suggest that true adsorbed films are likely extremely rare in the environment except under near-dry, ultra-high capillary pressure conditions. This result has significant implications for understanding fate and transport within the unsaturated zone. Preliminary simulations exploring the impact on transport will be discussed.

  12. Coupled computational fluid-thermal investigation of hypersonic flow over a quilted dome surface

    NASA Astrophysics Data System (ADS)

    Ostoich, Christopher; Bodony, Daniel; Geubelle, Philippe

    2009-11-01

    The hypersonic environment is characterized by the high temperatures that are generated in the fluid at a vehicle surface. In the effort to enable the operation of lightweight, reusable hypersonic vehicles, flexible, thin thermal protection panels have been considered to mitigate thermal loads. High surface temperatures create through-the-thickness thermal gradients which cause the panels to bow, resulting in changes to the external flow field and leading to a fully coupled fluid-thermal-structural problem. Certain aspects of the fluid-thermal (no structural) coupling were examined in a 1980s NASA Langley experiment of a Mach 5.74 laminar boundary past an array of spherical domes. We reexamine this case computationally using a high-fidelity Navier-Stokes solver coupled with a thermal solver to investigate the effects on the flow and resulting heat load on the structure due to the bowed panels. Specifically the surface temperature, surface heat flux, and downstream boundary developments are reported, and compared with experiment.

  13. Ertel's vorticity theorem and new flux surfaces in multi-fluid plasmas

    SciTech Connect

    Hameiri, Eliezer

    2013-09-15

    Dedicated to Professor Harold Weitzner on the occasion of his retirement“Say to wisdom ‘you are my sister,’ and to insight ‘you are my relative.’”—Proverbs 7:4Based on an extension to plasmas of Ertel's classical vorticity theorem in fluid dynamics, it is shown that for each species in a multi-fluid plasma there can be constructed a set of nested surfaces that have this species' fluid particles confined within them. Variational formulations for the plasma evolution and its equilibrium states are developed, based on the new surfaces and all of the dynamical conservation laws associated with them. It is shown that in the general equilibrium case, the energy principle lacks a minimum and cannot be used as a stability criterion. A limit of the variational integral yields the two-fluid Hall-magnetohydrodynamic (MHD) model. A further special limit yields MHD equilibria and can be used to approximate the equilibrium state of a Hall-MHD plasma in a perturbative way.

  14. Bacterial migration and motion in a fluid phase and near a solid surface

    SciTech Connect

    Frymier, P.D. Jr.

    1995-01-01

    An understanding of the migration and motion of bacteria in a fluid phase and near solid surfaces is necessary to characterize processes such as the bioremediation of hazardous waste, the pathogenesis of infection, industrial biofouling and wastewater treatment, among others. This study addresses three questions concerning the prediction of the distribution of a population of bacteria in a fluid phase and the motion of bacteria near a solid surface: Under what conditions does a one-dimensional phenomenological model for the density of a population of chemotactic bacteria yield an adequate representation of the migration of bacteria subject to a one-dimensional attractant gradient? How are the values of transport coefficients obtained from experimental data affected by the use of the one-dimensional phenomenological model and also by the use of different descriptions of bacterial swimming behavior in a mathematically rigorous balance equation? How is the characteristic motion of bacteria swimming in a fluid affected by the presence of a solid phase? A computer simulation that rigorously models the movement of a large population of individual chemotactic bacteria in three dimensions is developed to test the validity of a one-dimensional phenomenological model for bacterial migration in a fluid.

  15. Current Inhalers Deliver Very Small Doses to the Lower Tracheobronchial Airways: Assessment of Healthy and Constricted Lungs.

    PubMed

    Walenga, Ross L; Longest, P Worth

    2016-01-01

    To evaluate the regional delivery of conventional aerosol medications, a new whole-lung computational fluid dynamics modeling approach was applied for metered dose inhaler (MDI) and dry powder inhaler (DPI) aerosols delivered to healthy and constricted airways. The computational fluid dynamics approach included complete airways through the third respiratory bifurcation (B3) and applied the new stochastic individual pathway modeling technique beyond B3 through the remainder of the conducting airways together with a new model of deposition in the alveolar region. Bronchiolar (B8-B15) deposition fraction values were low (∼1%) for both MDI and DPI aerosols with the healthy geometry, whereas delivery to the constricted model was even lower, with deposition fraction values of 0.89% and 0.81% for the MDI and DPI, respectively. Calculating dose per unit surface area for the commercial MDI and DPI products resulted in approximately 10(-3) μg/cm(2) in the lower tracheobronchial region of B8-B15 and 10(-4) μg/cm(2) in the alveolar region. Across the lung, dose per unit surface area varied by 2 orders of magnitude, which increased to 4 orders of magnitude when the mouth-throat region was included. The MDI and DPI both provided very low drug dose per unit surface area to the small tracheobronchial and alveolar airways.

  16. Surface properties and flow behavior of foams in relation to fluid displacement in porous media

    SciTech Connect

    Ling, T.F.T.

    1987-01-01

    Surface properties such as surface tension, surface viscosity, foaminess, foam quality, apparent foam viscosity, rate of drainage, bubble size distribution, etc., were investigated and correlated with fluid displacement in porous media. The effect of chain length compatability, i.e., similarity, on surface properties of foaming solutions and fluid displacement in porous media were also studied. Two mathematical models for foam flow through porous media were developed which can be used to predict foam viscosity and foam behavior in porous media. To better understand the foam stability, a numerical solution of the Poisson-Boltzmann equation in two dimensional bispherical coordinates was obtained and used to calculate the potential energy of interaction between two spherical bubbles. Predicted potential energies were consistent with results from other models. The effect of polymer on foam properties was also studied. The improvement of surface activity of the surfactants was due mainly to the effect of the excluded polymer volume and electrical double layers. The change of the surface properties of the polymer containing foam was dependent on the counterbalance of the rheology of the liquid films and the water content in the liquid films. These studies have been successfully applied to enhanced oil recovery and to characterization of biological polymers. A concept of surfactant-polymer-foam flooding is proposed, including the use of nonionic surfactants to form alcohol-free microemulsions and the injection of foam for the mobility control in heavy oil recovery.

  17. Pressure Distribution in a Squeeze Film Spherical Bearing with Rough Surfaces Lubricated by an Ellis Fluid

    NASA Astrophysics Data System (ADS)

    Jurczak, P.; Falicki, J.

    2016-08-01

    In this paper, the solution to a problem of pressure distribution in a curvilinear squeeze film spherical bearing is considered. The equations of motion of an Ellis pseudo-plastic fluid are presented. Using Christensen's stochastic model of rough surfaces, different forms of Reynolds equation for various types of surface roughness pattern are obtained. The analytical solutions of these equations for the cases of externally pressurized bearing and squeeze film bearing are presented. Analytical solutions for the film pressure are found for the longitudinal and circumferential roughness patterns. As a result the formulae expressing pressure distribution in the clearance of bearing lubricated by an Ellis fluid was obtained. The numerical considerations for a spherical bearing are given in detail.

  18. Simultaneous optical sensing of multiple fluids via spatially multiplexed surface-multiplasmonic-resonance imaging

    NASA Astrophysics Data System (ADS)

    Swiontek, Stephen E.; Lakhtakia, Akhlesh

    2016-09-01

    Multiple surface-plasmon-polariton (SPP) waves are guided by the interface of a metal and a chiral sculptured thin film (STF) at a single wavelength. Spatially multiplexed 4-quadrant chips comprising a lanthanum-fluoride chiral STF embedded with a silver-nanoparticle layer were deposited atop an aluminum-coated glass substrate, each quadrant functioning as an autonomous sensor. The void regions of the chiral STF in each quadrant were in filtrated with sucrose solutions of increasing molarity and deployed in a prism-coupled surface-multi-plasmonics-resonance- imaging (SMPRI) machine. The angular locations of the SPP-wave modes shift as the molarity of the fluid increases, thus demonstrating simultaneous sensing of fluids via SMPRI.

  19. Bulk and surface acoustic waves in solid-fluid Fibonacci layered materials.

    PubMed

    Quotane, I; El Boudouti, E H; Djafari-Rouhani, B; El Hassouani, Y; Velasco, V R

    2015-08-01

    We study theoretically the propagation and localization of acoustic waves in quasi-periodic structures made of solid and fluid layers arranged according to a Fibonacci sequence. We consider two types of structures: either a given Fibonacci sequence or a periodic repetition of a given sequence called Fibonacci superlattice. Various properties of these systems such as: the scaling law and the self-similarity of the transmission spectra or the power law behavior of the measure of the energy spectrum have been highlighted for waves of sagittal polarization in normal and oblique incidence. In addition to the allowed modes which propagate along the system, we study surface modes induced by the surface of the Fibonacci superlattice. In comparison with solid-solid layered structures, the solid-fluid systems exhibit transmission zeros which can break the self-similarity behavior in the transmission spectra for a given sequence or induce additional gaps other than Bragg gaps in a periodic structure.

  20. Numerical investigation of thermally stratified Williamson fluid flow over a cylindrical surface via Keller box method

    NASA Astrophysics Data System (ADS)

    Bilal, S.; Rehman, Khalil Ur; Malik, M. Y.

    Present study is addressed to express the implementation of Keller-Box technique on physical problem in the field of fluid rheology, for this purpose the Williamson fluid flow is considered along a cylindrical stretching surface manifested with temperature stratification. The flow model is translated mathematically in terms of differential equations. Numerical simulation is executed to trace out the solution structure of developed differential system. The graphical outcomes for the flow regime of two different geometries (i-e cylindrical and plane surface) are reported and examined towards involved physical parameters. Furthermore, the local skin friction coefficient and local Nusselt number are computed numerically. A remarkable agreement of present study is noticed with the previously published results, which confirms the implementation and validation of Keller-Box scheme and it will serve as a helping source for the future correspondence.

  1. Airway acidification initiates host defense abnormalities in cystic fibrosis mice

    PubMed Central

    Shah, Viral S.; Meyerholz, David K.; Tang, Xiao Xiao; Reznikov, Leah; Alaiwa, Mahmoud Abou; Ernst, Sarah E.; Karp, Philip H.; Wohlford-Lenane, Christine L.; Heilmann, Kristopher P.; Leidinger, Mariah R.; Allen, Patrick D.; Zabner, Joseph; McCray, Paul B.; Ostedgaard, Lynda S.; Stoltz, David A.; Randak, Christoph O.; Welsh, Michael J.

    2016-01-01

    Cystic fibrosis (CF) is caused by mutations in the gene that encodes the cystic fibrosis transmembrane conductance regulator (CFTR) anion channel. In humans and pigs, the loss of CFTR impairs respiratory host defenses, causing airway infection. But CF mice are spared. We found that in all three species, CFTR secreted bicarbonate into airway surface liquid. In humans and pigs lacking CFTR, unchecked H+ secretion by the nongastric H+/K+ adenosine triphosphatase (ATP12A) acidified airway surface liquid, which impaired airway host defenses. In contrast, mouse airways expressed little ATP12A and secreted minimal H+; consequently, airway surface liquid in CF and non-CF mice had similar pH. Inhibiting ATP12A reversed host defense abnormalities in human and pig airways. Conversely, expressing ATP12A in CF mouse airways acidified airway surface liquid, impaired defenses, and increased airway bacteria. These findings help explain why CF mice are protected from infection and nominate ATP12A as a potential therapeutic target for CF. PMID:26823428

  2. Integrating aerodynamic surface modeling for computational fluid dynamics with computer aided structural analysis, design, and manufacturing

    NASA Technical Reports Server (NTRS)

    Thorp, Scott A.

    1992-01-01

    This presentation will discuss the development of a NASA Geometry Exchange Specification for transferring aerodynamic surface geometry between LeRC systems and grid generation software used for computational fluid dynamics research. The proposed specification is based on a subset of the Initial Graphics Exchange Specification (IGES). The presentation will include discussion of how the NASA-IGES standard will accommodate improved computer aided design inspection methods and reverse engineering techniques currently being developed. The presentation is in viewgraph format.

  3. Global Solvability of a Free Boundary Three-Dimensional Incompressible Viscoelastic Fluid System with Surface Tension

    NASA Astrophysics Data System (ADS)

    Xu, Li; Zhang, Ping; Zhang, Zhifei

    2013-06-01

    Motivated by Beale (Commun Pure Appl Math 34:359-392, 1981; Arch Ration Mech Anal 84:307-352, 1983/1984), we investigate the global well-posedness of a free boundary problem of a three-dimensional incompressible viscoelastic fluid system in an infinite strip and with surface tension on the upper free boundary, provided that the initial data is sufficiently close to the equilibrium state.

  4. Relative Contribution of P5 and Hap Surface Proteins to Nontypable Haemophilus influenzae Interplay with the Host Upper and Lower Airways.

    PubMed

    Euba, Begoña; Moleres, Javier; Viadas, Cristina; Ruiz de los Mozos, Igor; Valle, Jaione; Bengoechea, José Antonio; Garmendia, Junkal

    2015-01-01

    Nontypable Haemophilus influenzae (NTHi) is a major cause of opportunistic respiratory tract disease, and initiates infection by colonizing the nasopharynx. Bacterial surface proteins play determining roles in the NTHi-airways interplay, but their specific and relative contribution to colonization and infection of the respiratory tract has not been addressed comprehensively. In this study, we focused on the ompP5 and hap genes, present in all H. influenzae genome sequenced isolates, and encoding the P5 and Hap surface proteins, respectively. We employed isogenic single and double mutants of the ompP5 and hap genes generated in the pathogenic strain NTHi375 to evaluate P5 and Hap contribution to biofilm growth under continuous flow, to NTHi adhesion, and invasion/phagocytosis on nasal, pharyngeal, bronchial, alveolar cultured epithelial cells and alveolar macrophages, and to NTHi murine pulmonary infection. We show that P5 is not required for bacterial biofilm growth, but it is involved in NTHi interplay with respiratory cells and in mouse lung infection. Mechanistically, P5NTHi375 is not a ligand for CEACAM1 or α5 integrin receptors. Hap involvement in NTHi375-host interaction was shown to be limited, despite promoting bacterial cell adhesion when expressed in H. influenzae RdKW20. We also show that Hap does not contribute to bacterial biofilm growth, and that its absence partially restores the deficiency in lung infection observed for the ΔompP5 mutant. Altogether, this work frames the relative importance of the P5 and Hap surface proteins in NTHi virulence.

  5. Relative Contribution of P5 and Hap Surface Proteins to Nontypable Haemophilus influenzae Interplay with the Host Upper and Lower Airways

    PubMed Central

    Viadas, Cristina; Ruiz de los Mozos, Igor; Valle, Jaione; Bengoechea, José Antonio; Garmendia, Junkal

    2015-01-01

    Nontypable Haemophilus influenzae (NTHi) is a major cause of opportunistic respiratory tract disease, and initiates infection by colonizing the nasopharynx. Bacterial surface proteins play determining roles in the NTHi-airways interplay, but their specific and relative contribution to colonization and infection of the respiratory tract has not been addressed comprehensively. In this study, we focused on the ompP5 and hap genes, present in all H. influenzae genome sequenced isolates, and encoding the P5 and Hap surface proteins, respectively. We employed isogenic single and double mutants of the ompP5 and hap genes generated in the pathogenic strain NTHi375 to evaluate P5 and Hap contribution to biofilm growth under continuous flow, to NTHi adhesion, and invasion/phagocytosis on nasal, pharyngeal, bronchial, alveolar cultured epithelial cells and alveolar macrophages, and to NTHi murine pulmonary infection. We show that P5 is not required for bacterial biofilm growth, but it is involved in NTHi interplay with respiratory cells and in mouse lung infection. Mechanistically, P5NTHi375 is not a ligand for CEACAM1 or α5 integrin receptors. Hap involvement in NTHi375-host interaction was shown to be limited, despite promoting bacterial cell adhesion when expressed in H. influenzae RdKW20. We also show that Hap does not contribute to bacterial biofilm growth, and that its absence partially restores the deficiency in lung infection observed for the ΔompP5 mutant. Altogether, this work frames the relative importance of the P5 and Hap surface proteins in NTHi virulence. PMID:25894755

  6. Impact of airway morphological changes on pulmonary flows in scoliosis

    NASA Astrophysics Data System (ADS)

    Farrell, James; Garrido, Enrique; Valluri, Prashant

    2016-11-01

    The relationship between thoracic deformity in scoliosis and lung function is poorly understood. In a pilot study, we reviewed computed tomography (CT) routine scans of patients undergoing scoliosis surgery. The CT scans were processed to segment the anatomy of the airways, lung and spine. A three-dimensional model was created to study the anatomical relationship. Preliminary analysis showed significant airway morphological differences depending on the anterior position of the spine. A computational fluid dynamics (CFD) study was also conducted on the airway geometry using the inspiratory scans. The CFD model assuming non-compliant airway walls was capable of showing pressure drops in areas of high airway resistance, but was unable to predict regional ventilation differences. Our results indicate a dependence between the dynamic deformation of the airway during breathing and lung function. Dynamic structural deformation must therefore be incorporated within any modelling approaches to guide clinicians on the decision to perform surgical correction of the scoliosis.

  7. Investigation of the link between fluid shift and airway collapsibility as a mechanism for obstructive sleep apnea in congestive heart failure.

    PubMed

    Carlisle, Tom; Ward, Neil R; Atalla, Angela; Cowie, Martin R; Simonds, Anita K; Morrell, Mary J

    2017-01-01

    The increased prevalence of obstructive sleep apnea (OSA) in congestive heart failure (CHF) may be associated with rostral fluid shift. We investigated the effect of overnight rostral fluid shift on pharyngeal collapsibility (Pcrit), pharyngeal caliber (APmean), and apnea-hypopnea index (AHI) in CHF patients. Twenty-three optimally treated systolic CHF patients were studied. Neck circumference was measured immediately prior to sleep in the evening and immediately after waking in the morning as a marker of rostral fluid shift. Pcrit was measured during sleep, early and late in the night. APmean was measured using acoustic reflection at the same times as neck circumference measurements. 15/23 CHF patients experienced an overnight increase in neck circumference; overall neck circumference significantly increased overnight (mean±SD, evening: 41.7 ± 3.2 cm; morning: 42.3 ± 3.1 cm; P = 0.03). Pcrit increased significantly overnight (early-night: -3.8 ± 3.3 cmH2O; late-night: -2.6 ± 3.0 cmH2O; P = 0.03) and APmean decreased (evening: 4.2 ± 1.3 cm(2); morning: 3.7 ± 1.3 cm(2); P = 0.006). The total AHI correlated with neck circumference (r = 0.4; P = 0.04) and Pcrit (r = 0.5; P = 0.01). APmean correlated with neck circumference (r = -0.47; P = 0.02). There was no significant change in AHI between the first and second half of the night (first-half: 12.9 ± 12.4/h; second-half: 13.7 ± 13.3/h; P = 0.6). Overnight rostral fluid shift was associated with increased pharyngeal collapsibility and decreased pharyngeal caliber during sleep in CHF patients. Rostral fluid shift may be an important mechanism of OSA in this patient group.

  8. Modified two-fluid model of conductivity for superconducting surface resistance calculation. Master's thesis

    SciTech Connect

    Linden, D.S.

    1993-05-01

    The traditional two-fluid model of superconducting conductivity was modified to make it accurate, while remaining fast, for designing and simulating microwave devices. The modification reflects the BCS coherence effects in the conductivity of a superconductor, and is incorporated through the ratio of normal to superconducting electrons. This modified ratio is a simple analytical expression which depends on frequency, temperature and material parameters. This modified two-fluid model allows accurate and rapid calculation of the microwave surface impedance of a superconductor in the clean and dirty limits and in the weak- and strong-coupled regimes. The model compares well with surface resistance data for Nb and provides insight into Nb3Sn and Y1Ba2Cu3O(7-delta). Numerical calculations with the modified two-fluid model are an order of magnitude faster than the quasi-classical program by Zimmermann (1), and two to five orders of magnitude faster than Halbritter's BCS program (2) for surface resistance.

  9. Vapor-liquid surface tension of strong short-range Yukawa fluid.

    PubMed

    Odriozola, G; Bárcenas, M; Orea, P

    2011-04-21

    The thermodynamic properties of strong short-range attractive Yukawa fluids, κ = 10, 9, 8, and 7, are determined by combining the slab technique with the standard and the replica exchange Monte Carlo (REMC) methods. A good agreement was found among the coexistence curves of these systems calculated by REMC and those previously reported in the literature. However, REMC allows exploring the coexistence at lower temperatures, where dynamics turns glassy. To obtain the surface tension we employed, for both methods, a procedure that yields the pressure tensor components for discontinuous potentials. The surface tension results obtained by the standard MC and REMC techniques are in good agreement.

  10. The Role of Bacterial Secretion Systems in the Virulence of Gram-Negative Airway Pathogens Associated with Cystic Fibrosis

    PubMed Central

    Depluverez, Sofie; Devos, Simon; Devreese, Bart

    2016-01-01

    Cystic fibrosis (CF) is the most common lethal inherited disorder in Caucasians. It is caused by mutation of the CF transmembrane conductance regulator (CFTR) gene. A defect in the CFTR ion channel causes a dramatic change in the composition of the airway surface fluid, leading to a highly viscous mucus layer. In healthy individuals, the majority of bacteria trapped in the mucus layer are removed and destroyed by mucociliary clearance. However, in the lungs of patients with CF, the mucociliary clearance is impaired due to dehydration of the airway surface fluid. As a consequence, patients with CF are highly susceptible to chronic or intermittent pulmonary infections, often causing extensive lung inflammation and damage, accompanied by a decreased life expectancy. This mini review will focus on the different secretion mechanisms used by the major bacterial CF pathogens to release virulence factors, their role in resistance and discusses the potential for therapeutically targeting secretion systems. PMID:27625638

  11. Pseudomonas aeruginosa pili and flagella mediate distinct binding and signaling events at the apical and basolateral surface of airway epithelium.

    PubMed

    Bucior, Iwona; Pielage, Julia F; Engel, Joanne N

    2012-01-01

    Pseudomonas aeruginosa, an important opportunistic pathogen of man, exploits numerous factors for initial attachment to the host, an event required to establish bacterial infection. In this paper, we rigorously explore the role of two major bacterial adhesins, type IV pili (Tfp) and flagella, in bacterial adherence to distinct host receptors at the apical (AP) and basolateral (BL) surfaces of polarized lung epithelial cells and induction of subsequent host signaling and pathogenic events. Using an isogenic mutant of P. aeruginosa that lacks flagella or utilizing beads coated with purified Tfp, we establish that Tfp are necessary and sufficient for maximal binding to host N-glycans at the AP surface of polarized epithelium. In contrast, experiments utilizing a P. aeruginosa isogenic mutant that lacks Tfp or using beads coated with purified flagella demonstrate that flagella are necessary and sufficient for maximal binding to heparan sulfate (HS) chains of heparan sulfate proteoglycans (HSPGs) at the BL surface of polarized epithelium. Using two different cell-free systems, we demonstrate that Tfp-coated beads show highest binding affinity to complex N-glycan chains coated onto plastic plates and preferentially aggregate with beads coated with N-glycans, but not with single sugars or HS. In contrast, flagella-coated beads bind to or aggregate preferentially with HS or HSPGs, but demonstrate little binding to N-glycans. We further show that Tfp-mediated binding to host N-glycans results in activation of phosphatidylinositol 3-kinase (PI3K)/Akt pathway and bacterial entry at the AP surface. At the BL surface, flagella-mediated binding to HS activates the epidermal growth factor receptor (EGFR), adaptor protein Shc, and PI3K/Akt, and induces bacterial entry. Remarkably, flagella-coated beads alone can activate EGFR and Shc. Together, this work provides new insights into the intricate interactions between P. aeruginosa and lung epithelium that may be potentially useful

  12. Mechanical Properties of the Upper Airway

    PubMed Central

    Strohl, Kingman P.; Butler, James P.; Malhotra, Atul

    2013-01-01

    The importance of the upper airway (nose, pharynx, and larynx) in health and in the pathogenesis of sleep apnea, asthma, and other airway diseases, discussed elsewhere in the Comprehensive Physiology series, prompts this review of the biomechanical properties and functional aspects of the upper airway. There is a literature based on anatomic or structural descriptions in static circumstances, albeit studied in limited numbers of individuals in both health and disease. As for dynamic features, the literature is limited to studies of pressure and flow through all or parts of the upper airway and to the effects of muscle activation on such features; however, the links between structure and function through airway size, shape, and compliance remain a topic that is completely open for investigation, particularly through analyses using concepts of fluid and structural mechanics. Throughout are included both historically seminal references, as well as those serving as signposts or updated reviews. This article should be considered a resource for concepts needed for the application of biomechanical models of upper airway physiology, applicable to understanding the pathophysiology of disease and anticipated results of treatment interventions. PMID:23723026

  13. Nasal Drug Absorption from Powder Formulations: Effect of Fluid Volume Changes on the Mucosal Surface.

    PubMed

    Tanaka, Akiko; Furubayashi, Tomoyuki; Enomura, Yuki; Hori, Tomoki; Shimomura, Rina; Maeda, Chiaki; Kimura, Shunsuke; Inoue, Daisuke; Kusamori, Kosuke; Katsumi, Hidemasa; Sakane, Toshiyasu; Yamamoto, Akira

    2017-01-01

    The effect of changes in the mucosal fluid volume on the nasal drug absorption of powder formulations was evaluated using warfarin (WF), piroxicam (PXC), and norfloxacin (NFX) as model drugs. Lactose and sodium chloride (NaCl), which are water soluble and small-sized chemicals that increase osmotic pressure after dissolution, were used as excipients to change the mucosal fluid volume. The in vitro study using a Madin-Darby canine kidney (MDCK) cell monolayer indicated that lactose and NaCl, sprayed over the surface of air interface monolayers, increased the fluid volume on the monolayer surface and enhanced the transepithelial transport of the model drugs. The in vivo animal study indicated that the nasal absorption of PXC is enhanced by lactose and NaCl after nasal administration of the powder formulations. This is likely due to the enhanced dissolution of PXC on fluid-rich nasal mucosa and an increase in the effective surface area for drug permeation, which lead to better nasal absorption. However, both excipients failed to increase the nasal absorption of WF and NFX. To clarify the mechanism of the drug-dependent effect of lactose and NaCl, the nasal residence of the formulation was examined using FD70 as a non-absorbable marker. The nasal clearance of FD70 was enhanced by lactose and NaCl, leading to a decrease in the nasal drug absorption. Lactose and NaCl caused no damage to the nasal tissue. These results indicate that the addition of water-soluble excipients such as lactose to powder formulations can enhance the nasal absorption of highly permeable but poorly soluble drugs.

  14. Silibinin attenuates allergic airway inflammation in mice

    SciTech Connect

    Choi, Yun Ho; Jin, Guang Yu; Guo, Hui Shu; Piao, Hong Mei; Li, Liang chang; Li, Guang Zhao; Lin, Zhen Hua; Yan, Guang Hai

    2012-10-26

    Highlights: Black-Right-Pointing-Pointer Silibinin diminishes ovalbumin-induced inflammatory reactions in the mouse lung. Black-Right-Pointing-Pointer Silibinin reduces the levels of various cytokines into the lung of allergic mice. Black-Right-Pointing-Pointer Silibinin prevents the development of airway hyperresponsiveness in allergic mice. Black-Right-Pointing-Pointer Silibinin suppresses NF-{kappa}B transcriptional activity. -- Abstract: Allergic asthma is a chronic inflammatory disease regulated by coordination of T-helper2 (Th2) type cytokines and inflammatory signal molecules. Silibinin is one of the main flavonoids produced by milk thistle, which is reported to inhibit the inflammatory response by suppressing the nuclear factor-kappa B (NF-{kappa}B) pathway. Because NF-{kappa}B activation plays a pivotal role in the pathogenesis of allergic inflammation, we have investigated the effect of silibinin on a mouse ovalbumin (OVA)-induced asthma model. Airway hyperresponsiveness, cytokines levels, and eosinophilic infiltration were analyzed in bronchoalveolar lavage fluid and lung tissue. Pretreatment of silibinin significantly inhibited airway inflammatory cell recruitment and peribronchiolar inflammation and reduced the production of various cytokines in bronchoalveolar fluid. In addition, silibinin prevented the development of airway hyperresponsiveness and attenuated the OVA challenge-induced NF-{kappa}B activation. These findings indicate that silibinin protects against OVA-induced airway inflammation, at least in part via downregulation of NF-{kappa}B activity. Our data support the utility of silibinin as a potential medicine for the treatment of asthma.

  15. Containment of a silicone fluid free surface in reduced gravity using barrier coatings

    NASA Technical Reports Server (NTRS)

    Pline, Alexander D.; Jacobson, Thomas P.

    1988-01-01

    In support of the Surface Tension Driven Convection Experiment planned for flight aboard the Space Shuttle, tests were conducted under reduced gravity in the 2.2-sec Drop Tower and the 5.0-sec Zero-G facility at the NASA Lewis Research Center. The dynamics of controlling the test fluid, a 10-cSt viscosity silicone fluid in a low gravity environment were investigated using different container designs and barrier coatings. Three container edge designs were tested without a barrier coating; a square edge, a sharp edge with a 45-deg slope, and a sawtooth edge. All three edge designs were successful in containing the fluid below the edge. G-jitter experiments were made in scaled down containers subjected to horizontal accelerations. The data showed that a barrier coating is effective in containing silicone fluid under g-levels up to 10 sup -1 sub g sub 0. In addition, a second barrier coating was found which has similar anti-wetting characteristics and is also more durable.

  16. Computer simulations of fluid flow over catalytic surfaces for water splitting

    NASA Astrophysics Data System (ADS)

    Chong, Leebyn; Dutt, Meenakshi

    2014-12-01

    Interfacial phenomena arising at solid/fluid interfaces depend upon the nanoscale structural and dynamical properties of the system. The presence of active sites on the solid surface that can bind with reactants in the fluid enables the investigation of reaction kinetics and its effect on multi-scale transport processes. We develop a coarse-grained particle-based model of the flow of reactants over a solid surface composed of close packed particles with embedded active sites. We investigate the role of the adsorption of the reactants onto these sites on the transport phenomena via the coarse-grained molecular dynamics technique. Our objective is to understand the role of nanoscale interfacial phenomena on the structural and dynamical properties of the system through the measurement of diffusion coefficients, velocity profiles, radial distribution functions, and mean residence times. We have investigated these properties as a function of the active site density, coarse graining effects and interaction strengths. Our results can potentially be used for future studies on multi-scale phenomena driven by reaction kinetics at solid/fluid interfaces, such as artificial photosynthesis cells.

  17. A surface energy analysis of mucoadhesion: contact angle measurements on polycarbophil and pig intestinal mucosa in physiologically relevant fluids.

    PubMed

    Lehr, C M; Bouwstra, J A; Boddé, H E; Junginger, H E

    1992-01-01

    The possible role of surface energy thermodynamics in mucoadhesion was investigated with Polycarbophil and pig intestinal mucosa. In separate experiments, the surface energy parameters of the substrate (mucosa) and the adhesive (polymer film) were determined by contact angle measurements on captive air/octane bubbles in three physiologically relevant test fluids (isotonic saline, artificial gastric fluid, and artificial intestinal fluid). Whereas the swollen Polycarbophil films were relatively hydrophilic as indicated by small water contact angles (22, 23, and 16 degrees), the water contact angles measured on mucosal tissue were significantly larger (61, 48, and 57 degrees). Hence, mucus was found to possess an appreciable hydrophobicity. The measured adhesive performance (force of detachment) between Polycarbophil and pig small intestinal mucosa was highest in nonbuffered saline medium, intermediate in gastric fluid, and minimal in intestinal fluid. In agreement with this trend, the mismatch in surface polarities between substrate and adhesive, calculated from the contact angle data, increased in the same order.

  18. Recent advances in computational fluid dynamics relevant to the modelling of pesticide flow on leaf surfaces.

    PubMed

    Glass, C Richard; Walters, Keith F A; Gaskell, Philip H; Lee, Yeaw C; Thompson, Harvey M; Emerson, David R; Gu, Xiao-Jun

    2010-01-01

    Increasing societal and governmental concern about the worldwide use of chemical pesticides is now providing strong drivers towards maximising the efficiency of pesticide utilisation and the development of alternative control techniques. There is growing recognition that the ultimate goal of achieving efficient and sustainable pesticide usage will require greater understanding of the fluid mechanical mechanisms governing the delivery to, and spreading of, pesticide droplets on target surfaces such as leaves. This has led to increasing use of computational fluid dynamics (CFD) as an important component of efficient process design with regard to pesticide delivery to the leaf surface. This perspective highlights recent advances in CFD methods for droplet spreading and film flows, which have the potential to provide accurate, predictive models for pesticide flow on leaf surfaces, and which can take account of each of the key influences of surface topography and chemistry, initial spray deposition conditions, evaporation and multiple droplet spreading interactions. The mathematical framework of these CFD methods is described briefly, and a series of new flow simulation results relevant to pesticide flows over foliage is provided. The potential benefits of employing CFD for practical process design are also discussed briefly.

  19. Intergranular solid-fluid phase transformations under stress: The effect of surface forces

    NASA Astrophysics Data System (ADS)

    Heidug, Wolfgang K.

    1995-04-01

    Existing work on mineral solubility in fluid-infiltrated and stressed rock has remained limited in that it has neglected surface forces. These forces are appreciable only when the fluid exists as a thin film, as in the grain-to-grain contact zone and in microcracks. Indeed, when the film thickness is of the order of 10(exp -9) m or so, the strength of the forces can be comparable to overburden stress at several kilometers depth. In this contribution we develop the thermodynamics of the phase reaction between nonhydrostatically stressed grains and an intervening water layer by using the concept of the disjoining pressure to account for surface forces acting in the grain-to-grain contact zone. Using a thermodynamic extremum principle, we find an extended version of Gibb's classical condition for the equilibrium of a stressed solid in contact with its solution phase. We then employ nonequilibrium thermodynamics to formulate kinetic equations describing phase boundary migration and intergranular mass transfer. It is demonstrated that surface forces weaken the efficacy with which diffusion removes dissolved material from the grain-to-grain contact zone and enhance the tendency of intergranular pressure solution to flatten initially rough surfaces.

  20. Slowly Adapting Sensory Units Have More Receptors in Large Airways than in Small Airways in Rabbits

    PubMed Central

    Liu, Jun; Song, Nana; Guardiola, Juan; Roman, Jesse; Yu, Jerry

    2016-01-01

    Sensory units of pulmonary slowly adapting receptors (SARs) are more active in large airways than in small airways. However, there is no explanation for this phenomenon. Although sensory structures in large airways resemble those in small airways, they are bigger and more complex. Possibly, a larger receptor provides greater surface area for depolarization, and thus has a lower activating threshold and/or a higher sensitivity to stretch, leading to more nerve electrical activities. Recently, a single sensory unit has been reported to contain multiple receptors. Therefore, sensory units in large airways may contain more SARs, which may contribute to high activities. To test this hypothesis, we used a double staining technique to identify sensory receptor sizes. We labeled the sensory structure with Na+/K+-ATPase antibodies and the myelin sheath with myelin basic protein (MBP) antibodies. A SAR can be defined as the end formation beyond MBP labeling. Thus, we are able to compare sizes of sensory structures and SARs in large (trachea and bronchi) vs. small (bronchioles <500 μm in diameter) airways in the rabbit. We found that even though the sensory structure was bigger in large airways than in small airways (3340 ± 223 vs. 1168 ± 103 μm2; P < 0.0001), there was no difference in receptor sizes (349 ± 14 vs. 326 ± 16 μm2; > 0.05). However, the sensory structure contains more SARs in large airways than in small airways (9.6 ± 0.6 vs. 3.6 ± 0.3; P < 0.0001). Thus, our data support the hypothesis that greater numbers of SARs in sensory units of large airways may contribute to higher activities. PMID:28018231

  1. Slowly Adapting Sensory Units Have More Receptors in Large Airways than in Small Airways in Rabbits.

    PubMed

    Liu, Jun; Song, Nana; Guardiola, Juan; Roman, Jesse; Yu, Jerry

    2016-01-01

    Sensory units of pulmonary slowly adapting receptors (SARs) are more active in large airways than in small airways. However, there is no explanation for this phenomenon. Although sensory structures in large airways resemble those in small airways, they are bigger and more complex. Possibly, a larger receptor provides greater surface area for depolarization, and thus has a lower activating threshold and/or a higher sensitivity to stretch, leading to more nerve electrical activities. Recently, a single sensory unit has been reported to contain multiple receptors. Therefore, sensory units in large airways may contain more SARs, which may contribute to high activities. To test this hypothesis, we used a double staining technique to identify sensory receptor sizes. We labeled the sensory structure with Na(+)/K(+)-ATPase antibodies and the myelin sheath with myelin basic protein (MBP) antibodies. A SAR can be defined as the end formation beyond MBP labeling. Thus, we are able to compare sizes of sensory structures and SARs in large (trachea and bronchi) vs. small (bronchioles <500 μm in diameter) airways in the rabbit. We found that even though the sensory structure was bigger in large airways than in small airways (3340 ± 223 vs. 1168 ± 103 μm(2); P < 0.0001), there was no difference in receptor sizes (349 ± 14 vs. 326 ± 16 μm(2); > 0.05). However, the sensory structure contains more SARs in large airways than in small airways (9.6 ± 0.6 vs. 3.6 ± 0.3; P < 0.0001). Thus, our data support the hypothesis that greater numbers of SARs in sensory units of large airways may contribute to higher activities.

  2. Fracture Surface Area Effects on Fluid Extraction and the Electrical Resistivity of Geothermal Reservoir Rocks

    SciTech Connect

    Roberts, J J; Detwiler, R L; Ralph, W; Bonner, B

    2002-05-09

    Laboratory measurements of the electrical resistivity of fractured analogue geothermal reservoir rocks were performed to investigate the resistivity contrast caused by active boiling and to determine the effects of variable fracture dimensions and surface area on water extraction. Experiments were performed at confining pressures up to 10 h4Pa (100 bars) and temperatures to 170 C. Fractured samples show a larger resistivity change at the onset of boiling than intact samples. Monitoring the resistivity of fractured samples as they equilibrate to imposed pressure and temperature conditions provides an estimate of fluid migration into and out of the matrix. Measurements presented are an important step toward using field electrical methods to quantitatively search for fractures, infer saturation, and track fluid migration in geothermal reservoirs.

  3. DeepPIV: Measuring in situ Biological-Fluid Interactions from the Surface to Benthos

    NASA Astrophysics Data System (ADS)

    Katija, K.; Sherman, A.; Graves, D.; Kecy, C. D.; Klimov, D.; Robison, B. H.

    2015-12-01

    The midwater region of the ocean (below the euphotic zone and above the benthos) is one of the largest ecosystems on our planet, yet it remains one of the least explored. Little known marine organisms that inhabit midwater have developed strategies for swimming and feeding that ultimately contributes to their evolutionary success, and may inspire engineering solutions for societally relevant challenges. Fluid mechanics governs the interactions that midwater organisms have with their physical environment, but limited access to midwater depths and lack of non-invasive methods to measure in situ small-scale fluid motions prevent these interactions from being better understood. Significant advances in underwater vehicle technologies have only recently improved access to midwater. Unfortunately, in situ small-scale fluid mechanics measurement methods are still lacking in the oceanographic community. Here we present DeepPIV, an instrumentation package that can be affixed to remotely operated underwater vehicles that quantifies small-scale fluid motions from the surface of the ocean down to 4000 m depths. Utilizing ambient, suspended particulate in the coastal regions of Monterey Bay, fluid-structure interactions are evaluated on a range of marine organisms in midwater. Initial science targets include larvaceans, biological equivalents of flapping flexible foils, that create mucus houses to filter food. Little is known about the structure of these mucus houses and the function they play in selectively filtering particles, and these dynamics can serve as particle-mucus models for human health. Using DeepPIV, we reveal the complex structures and flows generated within larvacean mucus houses, and elucidate how these structures function.

  4. Numerical analysis of respiratory flow patterns within human upper airway

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Liu, Yingxi; Sun, Xiuzhen; Yu, Shen; Gao, Fei

    2009-12-01

    A computational fluid dynamics (CFD) approach is used to study the respiratory airflow dynamics within a human upper airway. The airway model which consists of the airway from nasal cavity, pharynx, larynx and trachea to triple bifurcation is built based on the CT images of a healthy volunteer and the Weibel model. The flow characteristics of the whole upper airway are quantitatively described at any time level of respiratory cycle. Simulation results of respiratory flow show good agreement with the clinical measures, experimental and computational results in the literature. The air mainly passes through the floor of the nasal cavity in the common, middle and inferior nasal meatus. The higher airway resistance and wall shear stresses are distributed on the posterior nasal valve. Although the airways of pharynx, larynx and bronchi experience low shear stresses, it is notable that relatively high shear stresses are distributed on the wall of epiglottis and bronchial bifurcations. Besides, two-dimensional fluid-structure interaction models of normal and abnormal airways are built to discuss the flow-induced deformation in various anatomy models. The result shows that the wall deformation in normal airway is relatively small.

  5. INDUCED SPUTUM DERIVES FROM THE CENTRAL AIRWAYS: CONFIRMATION USING A RADIOLABELED AEROSOL BOLUS DELIVERY TECHNIQUE

    EPA Science Inventory

    Indirect evidence suggests that induced sputum derives from the surfaces of the bronchial airways. To confirm this experimentally, we employed a radiolabeled aerosol bolus delivery technique that preferentially deposits aerosol in the central airways in humans. We hypothesized th...

  6. Using SEM Analysis on Ion-Milled Shale Surface to Determine Shale-Fracturing Fluid Interaction

    NASA Astrophysics Data System (ADS)

    Lu, J.; Mickler, P. J.; Nicot, J. P.

    2014-12-01

    It is important to document and assess shale-fluid interaction during hydraulic fracturing (HF) in order to understand its impact on flowback water chemistry and rock property. A series of autoclave experiments were conducted to react shale samples from major oil and gas shales with synthetic HF containing various additives. To better determine mineral dissolution and precipitation at the rock-fluid interface, ion-milling technique was applied to create extremely flat rock surfaces that were examined before and after the autoclave experiments using a scanning electron microscope (SEM) coupled with energy dispersive spectroscopy (EDS) detectors. This method is able to reveal a level of detail not observable on broken surface or mechanically polished surface. It allows direct comparison of the same mineral and organic matter particles before and after the reaction experiments. Minerals undergone dissolution and newly precipitated materials are readily determined by comparing to the exact locations before reaction. The dissolution porosity and the thickness of precipitates can be quantified by tracing and measuring the geometry of the pores and precipitates. Changes in porosity and permeability were confirmed by mercury intrusion capillary tests.

  7. Measurements of Deposition, Lung Surface Area and Lung Fluid for Simulation of Inhaled Compounds

    PubMed Central

    Fröhlich, Eleonore; Mercuri, Annalisa; Wu, Shengqian; Salar-Behzadi, Sharareh

    2016-01-01

    Modern strategies in drug development employ in silico techniques in the design of compounds as well as estimations of pharmacokinetics, pharmacodynamics and toxicity parameters. The quality of the results depends on software algorithm, data library and input data. Compared to simulations of absorption, distribution, metabolism, excretion, and toxicity of oral drug compounds, relatively few studies report predictions of pharmacokinetics and pharmacodynamics of inhaled substances. For calculation of the drug concentration at the absorption site, the pulmonary epithelium, physiological parameters such as lung surface and distribution volume (lung lining fluid) have to be known. These parameters can only be determined by invasive techniques and by postmortem studies. Very different values have been reported in the literature. This review addresses the state of software programs for simulation of orally inhaled substances and focuses on problems in the determination of particle deposition, lung surface and of lung lining fluid. The different surface areas for deposition and for drug absorption are difficult to include directly into the simulations. As drug levels are influenced by multiple parameters the role of single parameters in the simulations cannot be identified easily. PMID:27445817

  8. Parallel Simulation of Three-Dimensional Free-Surface Fluid Flow Problems

    SciTech Connect

    BAER,THOMAS A.; SUBIA,SAMUEL R.; SACKINGER,PHILIP A.

    2000-01-18

    We describe parallel simulations of viscous, incompressible, free surface, Newtonian fluid flow problems that include dynamic contact lines. The Galerlin finite element method was used to discretize the fully-coupled governing conservation equations and a ''pseudo-solid'' mesh mapping approach was used to determine the shape of the free surface. In this approach, the finite element mesh is allowed to deform to satisfy quasi-static solid mechanics equations subject to geometric or kinematic constraints on the boundaries. As a result, nodal displacements must be included in the set of problem unknowns. Issues concerning the proper constraints along the solid-fluid dynamic contact line in three dimensions are discussed. Parallel computations are carried out for an example taken from the coating flow industry, flow in the vicinity of a slot coater edge. This is a three-dimensional free-surface problem possessing a contact line that advances at the web speed in one region but transitions to static behavior in another part of the flow domain. Discussion focuses on parallel speedups for fixed problem size, a class of problems of immediate practical importance.

  9. Virtual Surface Characteristics of a Tactile Display Using Magneto-Rheological Fluids

    PubMed Central

    Lee, Chul-Hee; Jang, Min-Gyu

    2011-01-01

    Virtual surface characteristics of tactile displays are investigated to characterize the feeling of human touch for a haptic interface application. In order to represent the tactile feeling, a prototype tactile display incorporating Magneto-Rheological (MR) fluid has been developed. Tactile display devices simulate the finger’s skin to feel the sensations of contact such as compliance, friction, and topography of the surface. Thus, the tactile display can provide information on the surface of an organic tissue to the surgeon in virtual reality. In order to investigate the compliance feeling of a human finger’s touch, normal force responses of a tactile display under various magnetic fields have been assessed. Also, shearing friction force responses of the tactile display are investigated to simulate the action of finger dragging on the surface. Moreover, different matrix arrays of magnetic poles are applied to form the virtual surface topography. From the results, different tactile feelings are observed according to the applied magnetic field strength as well as the arrays of magnetic poles combinations. This research presents a smart tactile display technology for virtual surfaces. PMID:22163769

  10. Contact angle hysteresis on superhydrophobic surfaces: an ionic liquid probe fluid offers mechanistic insight.

    PubMed

    Krumpfer, Joseph W; Bian, Pei; Zheng, Peiwen; Gao, Lichao; McCarthy, Thomas J

    2011-03-15

    Silicon/silicon dioxide surfaces containing 3 μm (width) × 6 μm (length) × 40 μm (height) staggered rhombus posts were prepared using photolithography and hydrophobized using a perfluoroalkyl-containing monofunctional silane. These surfaces exhibit water contact angles of θ(A)/θ(R) = 169°/156°. Water drops come to rest on a carefully aligned horizontal sample but roll when the surface is tilted slightly. No visible trail or evidence of water "left behind" at the receding edge of the drop is apparent on surfaces that water drops have rolled on or on samples removed from water through the air-water interface. When dimethylbis(β-hydroxyethyl)ammonium methanesulfonate (N(+)S(-), a nonvolatile ionic liquid) is used as the liquid probe fluid (instead of water), contact angles of θ(A)/θ(R) = 164°/152° are observed and ∼3-μm-diameter sessile drops are visible (by scanning electron microscopy - SEM) on the top of every post of a sample drawn out of this liquid. We interpret the formation of these sessile microdrops as arising from microcapillary bridge failure that occurs during receding events and emphasize that the capillary bridges rupture in primarily a tensile failure mode. Smaller sessile drops could be prepared using mixtures of water and N(+)S(-). Microdroplets of N(+)S(-) were also observed to form selectively at particular features on surfaces containing square holes separated by ridges. This suggests that pinning sites can be identified using microscopy and this ionic liquid probe fluid.

  11. High-Speed Transport of Fluid Drops and Solid Particles via Surface Acoustic Waves

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph; Bao, Xiaoqi; Sherrit, Stewart; Badescu, Mircea; Lih, Shyh-shiuh

    2012-01-01

    A compact sampling tool mechanism that can operate at various temperatures, and transport and sieve particle sizes of powdered cuttings and soil grains with no moving parts, has been created using traveling surface acoustic waves (SAWs) that are emitted by an inter-digital transducer (IDT). The generated waves are driven at about 10 MHz, and it causes powder to move towards the IDT at high speed with different speeds for different sizes of particles, which enables these particles to be sieved. This design is based on the use of SAWs and their propelling effect on powder particles and fluids along the path of the waves. Generally, SAWs are elastic waves propagating in a shallow layer of about one wavelength beneath the surface of a solid substrate. To generate SAWs, a piezoelectric plate is used that is made of LiNbO3 crystal cut along the x-axis with rotation of 127.8 along the y-axis. On this plate are printed pairs of fingerlike electrodes in the form of a grating that are activated by subjecting the gap between the electrodes to electric field. This configuration of a surface wave transmitter is called IDT. The IDT that was used consists of 20 pairs of fingers with 0.4-mm spacing, a total length of 12.5 mm. The surface wave is produced by the nature of piezoelectric material to contract or expand when subjected to an electric field. Driving the IDT to generate wave at high amplitudes provides an actuation mechanism where the surface particles move elliptically, pulling powder particles on the surface toward the wavesource and pushing liquids in the opposite direction. This behavior allows the innovation to separate large particles and fluids that are mixed. Fluids are removed at speed (7.5 to 15 cm/s), enabling this innovation of acting as a bladeless wiper for raindrops. For the windshield design, the electrodes could be made transparent so that they do not disturb the driver or pilot. Multiple IDTs can be synchronized to transport water or powder over larger

  12. Experimental assessment of Owen's second hypothesis on surface shear stress induced by a fluid during sediment saltation

    NASA Astrophysics Data System (ADS)

    Walter, B.; Horender, S.; Voegeli, C.; Lehning, M.

    2014-09-01

    A widely used, yet thus far unproven, fluid dynamical hypothesis originally presented by P. R. Owen 50 years ago, states that the surface shear stress induced by a fluid on the ground during equilibrium sediment saltation is constant and independent of the magnitude of the fluid velocity and consequently the particle mass flux. This hypothesis is one of the key elements in almost all current model descriptions of sediment erosion. We measured the surface shear stress in a drifting-sand wind tunnel and found Owen's hypothesis being merely an approximation of the real situation. A significant decrease of the fluid stress with increasing wind velocities was measured for low to intermediate particle mass fluxes. For high particle mass fluxes, Owen's hypothesis essentially holds, although a slight increase of the fluid stress was measured.

  13. Flow of Oldroyd 8-constant fluid in a scraped surface heat exchanger

    NASA Astrophysics Data System (ADS)

    Imran, A.; Siddiqui, A. M.; Rana, M. A.

    2016-12-01

    In this work the flow of the Oldroyd 8-constant fluid model in a scraped surface heat exchanger (SSHE) is studied. We have taken the steady incompressible isothermal flow of a fluid around a periodic arrangement of pivoted scraper blades in a channel for a generalized Poiseuille flow, and the flow is modeled using the lubrication-approximation theory (LAT), where as in SSHE the gaps between the blades and the device walls are narrow. Using these approximations we got the non-linear boundary value problem which is solved using the Adomian decomposition method. Expressions for velocity profiles for different regions, flow rates, stream function are obtained. Graphical and tabular representation for the velocity profile and for the different flow parameters involved is also incorporated. Foodstuffs behave as non-Newtonian material, possess shear-thinning and shear-thickening effects, so they are considered for the understanding of non-Newtonian effects inside the SSHE Oldroyd 8-constant fluid model. In addition to food industry this work will also be helpful in pharmaceutical and chemical industries as most of the materials used in the industry are non-Newtonian in nature.

  14. Passive movement of human soft palate during respiration: A simulation of 3D fluid/structure interaction.

    PubMed

    Zhu, Jian Hua; Lee, Heow Pueh; Lim, Kian Meng; Lee, Shu Jin; Teo, Li San Lynette; Wang, De Yun

    2012-07-26

    This study reconstructed a three dimensional fluid/structure interaction (FSI) model to investigate the compliance of human soft palate during calm respiration. Magnetic resonance imaging scans of a healthy male subject were obtained for model reconstruction of the upper airway and the soft palate. The fluid domain consists of nasal cavity, nasopharynx and oropharynx. The airflow in upper airway was assumed as laminar and incompressible. The soft palate was assumed as linear elastic. The interface between airway and soft palate was the FSI interface. Sinusoidal variation of velocity magnitude was applied at the oropharynx corresponding to ventilation rate of 7.5L/min. Simulations of fluid model in upper airway, FSI models with palatal Young's modulus of 7539Pa and 3000Pa were carried out for two cycles of respiration. The results showed that the integrated shear forces over the FSI interface were much smaller than integrated pressure forces in all the three directions (axial, coronal and sagittal). The total integrated force in sagittal direction was much smaller than that of coronal and axial directions. The soft palate was almost static during inspiration but moved towards the posterior pharyngeal wall during expiration. In conclusion, the displacement of human soft palate during respiration was mainly driven by air pressure around the surface of the soft palate with minimal contribution of shear stress of the upper airway flow. Despite inspirational negative pressure, expiratory posterior movement of soft palate could be another factor for the induction of airway collapse.

  15. Computational fluid dynamic study on obstructive sleep apnea syndrome treated with maxillomandibular advancement.

    PubMed

    Yu, Chung-Chih; Hsiao, Hung-Da; Lee, Lung-Cheng; Yao, Chih-Min; Chen, Ning-Hung; Wang, Chau-Jan; Chen, Yu-Ray

    2009-03-01

    Maxillomandibular advancement is one of the treatments available for obstructive sleep apnea. The influence of this surgery on the upper airway and its mechanism are not fully understood. The present research simulates the flow fields of narrowed upper airways of 2 patients with obstructive sleep apnea treated with maxillomandibular advancement. The geometry of the upper airway was reconstructed from computed tomographic images taken before and after surgery. The consequent three-dimensional surface model was rendered for measurement and computational fluid dynamics simulation. Patients showed clinical improvement 6 months after surgery. The cross-sectional area of the narrowest part of the upper airway was increased in all dimensions. The simulated results showed a less constricted upper airway, with less velocity change and a decreased pressure gradient across the whole conduit during passage of air. Less breathing effort is therefore expected to achieve equivalent ventilation with the postoperative airway. This study demonstrates the possibility of computational fluid dynamics in providing information for understanding the pathogenesis of OSA and the effects of its treatment.

  16. Effects of fluid recirculation on mass transfer from the arterial surface to flowing blood

    NASA Astrophysics Data System (ADS)

    Zhang, Zhi-Guo; Zhang, Xi-Wen; Liu, Ying-Xi

    2012-06-01

    The effect of disturbed flow on the mass transfer from arterial surface to flowing blood was studied numerically, and the results were compared with that of our previous work. The arterial wall was assumed to be viscoelastic and the blood was assumed to be incompressible and non-Newtonian fluid, which is more close to human arterial system. Numerical results indicated that the mass transfer from the arterial surface to flowing blood in regions of disturbed flow is positively related with the wall shear rates and it is significantly enhanced in regions of disturbed flow with a local minimum around the reattachment point which is higher than the average value of the downstream. Therefore, it may be implied that the accumulation of cholesterol or lipids within atheromatous plaques is not caused by the reduced efflux of cholesterol or lipids, but by the infiltration of the LDL (low-density lipoprotein) from the flowing blood to the arterial wall.

  17. Surface fluid-swellable chitosan fiber as the wound dressing material.

    PubMed

    Xia, Guixue; Lang, Xuqian; Kong, Ming; Cheng, Xiaojie; Liu, Ya; Feng, Chao; Chen, Xiguang

    2016-01-20

    The objective of this study was to develop a novel surface fluid-swellable chitosan (SFSC) fiber for potential wound dressing. The SFSC fiber was successfully prepared by surface modification of chitosan fiber with succinic anhydride, which was characterized by FTIR and solid-state (13)C NMR. The SFSC fiber exhibited better water absorption capacity (approx. 2980%) and stronger antibacterial activities (both above 90%) against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) than chitosan fiber (both below 75%). The cell viability was more than 90% after treated with the SFSC fiber extract, which demonstrated that SFSC fiber had low cytotoxicity towards mouse embryo fibroblasts (MEFs). The SFSC fiber could promote wound healing with advanced development of granulation tissue and epithelial coverage compared with the control (gauze-covered) group. The results indicated that SFSC fiber had great potential to be used as wound dressing material.

  18. Effect of surface texture and working gap on the braking performance of the magnetorheological fluid brake

    NASA Astrophysics Data System (ADS)

    Wang, Na; Li, Dong Heng; Li Song, Wan; Chao Xiu, Shi; Zhi Meng, Xiang

    2016-10-01

    In this paper, the effect of the surface textures of braking disc on the braking performance is experimentally investigated under the conditions of different working gaps and applied currents. For this purpose, a new configuration of magnetorheological fluid brake (MRB) with adjustable working gap is developed to improve the manufacturing accuracy and cost, and to reduce the problem of replacing the braking disc. In addition, the braking discs with three types of surface texture are designed and machined. Based on the test bed developed for the proposed MRB, a series of experiments are carried out on the manufactured prototype and the results are presented to obtain the relationship among the surface texture of the braking disc, applied current, working gap and the braking performance. The results show that the braking torque is significantly influenced by the working gap and surface texture of the braking disc, and the maximum braking torque is obtained on the conditions of 0.25 mm working gap and the braking disc with square surface texture.

  19. Parallel Simulation of Three-Dimensional Free Surface Fluid Flow Problems

    SciTech Connect

    BAER,THOMAS A.; SACKINGER,PHILIP A.; SUBIA,SAMUEL R.

    1999-10-14

    Simulation of viscous three-dimensional fluid flow typically involves a large number of unknowns. When free surfaces are included, the number of unknowns increases dramatically. Consequently, this class of problem is an obvious application of parallel high performance computing. We describe parallel computation of viscous, incompressible, free surface, Newtonian fluid flow problems that include dynamic contact fines. The Galerkin finite element method was used to discretize the fully-coupled governing conservation equations and a ''pseudo-solid'' mesh mapping approach was used to determine the shape of the free surface. In this approach, the finite element mesh is allowed to deform to satisfy quasi-static solid mechanics equations subject to geometric or kinematic constraints on the boundaries. As a result, nodal displacements must be included in the set of unknowns. Other issues discussed are the proper constraints appearing along the dynamic contact line in three dimensions. Issues affecting efficient parallel simulations include problem decomposition to equally distribute computational work among a SPMD computer and determination of robust, scalable preconditioners for the distributed matrix systems that must be solved. Solution continuation strategies important for serial simulations have an enhanced relevance in a parallel coquting environment due to the difficulty of solving large scale systems. Parallel computations will be demonstrated on an example taken from the coating flow industry: flow in the vicinity of a slot coater edge. This is a three dimensional free surface problem possessing a contact line that advances at the web speed in one region but transitions to static behavior in another region. As such, a significant fraction of the computational time is devoted to processing boundary data. Discussion focuses on parallel speed ups for fixed problem size, a class of problems of immediate practical importance.

  20. PRECISION CLEANING OF SEMICONDUCTOR SURFACES USING CARBON DIOXIDE-BASED FLUIDS

    SciTech Connect

    J. RUBIN; L. SIVILS; A. BUSNAINA

    1999-07-01

    The Los Alamos National Laboratory, on behalf of the Hewlett-Packard Company, is conducting tests of a closed-loop CO{sub 2}-based supercritical fluid process, known as Supercritical CO{sub 2} Resist Remover (SCORR). We have shown that this treatment process is effective in removing hard-baked, ion-implanted photoresists, and appears to be fully compatible with metallization systems. We are now performing experiments on production wafers to assess not only photoresist removal, but also residual surface contamination due to particulate and trace metals. Dense-phase (liquid or supercritical) CO{sub 2}, since it is non-polar, acts like an organic solvent and therefore has an inherently high volubility for organic compounds such as oils and greases. Also, dense CO{sub 2} has a low-viscosity and a low dielectric constant. Finally, CO{sub 2} in the liquid and supercritical fluid states can solubilize metal completing agents and surfactants. This combination of properties has interesting implications for the removal not only of organic films, but also trace metals and inorganic particulate. In this paper we discuss the possibility of using CO{sub 2} as a precision-cleaning solvent, with particular emphasis on semiconductor surfaces.

  1. Convective Instability of a Gravity Modulated Fluid Layer with Surface Tension Variation

    NASA Technical Reports Server (NTRS)

    Skarda, J. Raymond Lee

    1998-01-01

    Gravity modulation of an unbounded fluid layer with surface tension variations along its free surface is investigated. In parameter space of (wavenumber, Marangoni number) modulation has a destabilizing effect on the unmodulated neutral stability curve for large Prandtl number, Pr, and small modulation frequency, Omega, while a stabilizing effect is observed for small Pr and large Omega. As Omega yields infinity, the modulated neutral stability curves approach the unmodulated neutral stability curve. At certain values of Pr and L2 multiple minima are observed and the neutral stability curves become highly distorted. Closed regions of subharmonic instability are also observed. Alternating regions of synchronous and subharmonic instability separated by very thin stable regions are observed in (1/Omega,g(sub 1)) space for the singly diffusive cases. Quasiperiodic behavior in addition to the synchronous and subharmonic responses, are observed for the case of a double diffusive fluid layer. Minimum acceleration amplitudes were observed to closely correspond with a subharmonic response, Lambda(sub im) = Omega/2 .

  2. Controversies in Pediatric Perioperative Airways

    PubMed Central

    Klučka, Jozef; Štourač, Petr; Štoudek, Roman; Ťoukálková, Michaela; Harazim, Hana; Kosinová, Martina

    2015-01-01

    Pediatric airway management is a challenge in routine anesthesia practice. Any airway-related complication due to improper procedure can have catastrophic consequences in pediatric patients. The authors reviewed the current relevant literature using the following data bases: Google Scholar, PubMed, Medline (OVID SP), and Dynamed, and the following keywords: Airway/s, Children, Pediatric, Difficult Airways, and Controversies. From a summary of the data, we identified several controversies: difficult airway prediction, difficult airway management, cuffed versus uncuffed endotracheal tubes for securing pediatric airways, rapid sequence induction (RSI), laryngeal mask versus endotracheal tube, and extubation timing. The data show that pediatric anesthesia practice in perioperative airway management is currently lacking the strong evidence-based medicine (EBM) data that is available for adult subpopulations. A number of procedural steps in airway management are derived only from adult populations. However, the objective is the same irrespective of patient age: proper securing of the airway and oxygenation of the patient. PMID:26759809

  3. Investigation of change in surface morphology of heated surfaces upon pool boiling of magnetic fluids under magnetic actuation

    NASA Astrophysics Data System (ADS)

    Shojaeian, Mostafa; Yildizhan, Melike-Mercan; Coşkun, Ömer; Ozkalay, Ebrar; Tekşen, Yiğit; Gulgun, Mehmet Ali; Funda Yagci Acar, Havva; Koşar, Ali

    2016-09-01

    Nanofluids are becoming a significant candidate for new generation coolants to be used in industrial applications. In order to reduce clustering and sedimentation of nanoparticles and improve the heat transfer performance simultaneously, magnetic fluids prepared with magnetic Fe3O4 nanoparticles dispersed in water, which were placed in a pool and were exposed to varying magnetic fields to actuate nanoparticles in the system. The effect of magnetic actuation on boiling heat transfer characteristics and on the surface morphology of the pool was examined. An average enhancement of 29% in boiling heat transfer was achieved via magnetic actuation with rather low magnetic field (magnetic flux densities up to 11 mT) densities. Furthermore, it was observed that magnetic actuation significantly prevented the deposition and sedimentation of the nanoparticles in the pool. Otherwise, significant destabilization of nanoparticles causing aggregation and heavy sedimentation was present as a result of the performed surface analysis. Even though magnetic actuation reduced the sedimentation on the macroscale, the deposition of a thick and porous film occurred onto the pool floor, increasing the surface roughness.

  4. Dynamics of Surfactant Liquid Plugs at Bifurcating Lung Airway Models

    NASA Astrophysics Data System (ADS)

    Tavana, Hossein

    2013-11-01

    A surfactant liquid plug forms in the trachea during surfactant replacement therapy (SRT) of premature babies. Under air pressure, the plug propagates downstream and continuously divides into smaller daughter plugs at continuously branching lung airways. Propagating plugs deposit a thin film on airway walls to reduce surface tension and facilitate breathing. The effectiveness of SRT greatly depends on the final distribution of instilled surfactant within airways. To understand this process, we investigate dynamics of splitting of surfactant plugs in engineered bifurcating airway models. A liquid plug is instilled in the parent tube to propagate and split at the bifurcation. A split ratio, R, is defined as the ratio of daughter plug lengths in the top and bottom daughter airway tubes and studied as a function of the 3D orientation of airways and different flow conditions. For a given Capillary number (Ca), orienting airways farther away from a horizontal position reduced R due to the flow of a larger volume into the gravitationally favored daughter airway. At each orientation, R increased with 0.0005 < Ca < 0.05. This effect diminished by decrease in airways diameter. This approach will help elucidate surfactant distribution in airways and develop effective SRT strategies.

  5. Acoustic simulation of a patient's obstructed airway.

    PubMed

    van der Velden, W C P; van Zuijlen, A H; de Jong, A T; Lynch, C T; Hoeve, L J; Bijl, H

    2016-01-01

    This research focuses on the numerical simulation of stridor; a high pitched, abnormal noise, resulting from turbulent airflow and vibrating tissue through a partially obstructed airway. Characteristics of stridor noise are used by medical doctors as indication for location and size of the obstruction. The relation between type of stridor and the various diseases associated with airway obstruction is unclear; therefore, simply listening to stridor is an unreliable diagnostic tool. The overall aim of the study is to better understand the relationship between characteristics of stridor noise and localization and size of the obstruction. Acoustic analysis of stridor may then in future simplify the diagnostic process, and reduce the need for more invasive procedures such as laryngoscopy under general anesthesia. In this paper, the feasibility of a coupled flow, acoustic and structural model is investigated to predict the noise generated by the obstruction as well as the propagation of the noise through the airways, taking into account a one-way coupled fluid, structure, and acoustic interaction components. The flow and acoustic solver are validated on a diaphragm and a simplified airway model. A realistic airway model of a patient suffering from a subglottic stenosis, derived from a real computed tomography scan, is further analyzed. Near the mouth, the broadband noise levels at higher frequencies increased with approximately 15-20 dB comparing the stridorous model with the healthy model, indicating stridorous sound.

  6. Surface-texture evolution of different chemical-vapor-deposited zinc sulfide flats polished with various magnetorheological fluids

    DOE PAGES

    Salzman, S.; Romanofsky, H. J.; Jacobs, S. D.; ...

    2015-08-19

    The macro-structure of chemical-vapor-deposited (CVD) zinc sulfide (ZnS) substrates is characterizedby cone-like structures that start growing at the early stages of deposition. As deposition progresses,these cones grow larger and reach centimeter size in height and millimeter size in width. It is challengingto polish out these features from the top layer, particularly for the magnetorheological finishing (MRF)process. A conventional MR fluid tends to leave submillimeter surface artifacts on the finished surface,which is a direct result of the cone-like structure. Here we describe the MRF process of polishing four CVD ZnS substrates, manufactured by four differentvendors, with conventional MR fluid at pHmore » 10 and zirconia-coated-CI (carbonyl iron) MR fluids at pH 4, 5,and 6. We report on the surface–texture evolution of the substrates as they were MRF polished with thedifferent fluids. We show that performances of the zirconia-coated-CI MR fluid at pH 4 are significantlyhigher than that of the same fluid at pH levels of 5 and 6 and moderately higher than that of a conventionalMR fluid at pH 10. An improvement in surface–texture variability from part to part was also observedwith the pH 4 MR fluid.« less

  7. Surface-texture evolution of different chemical-vapor-deposited zinc sulfide flats polished with various magnetorheological fluids

    SciTech Connect

    Salzman, S.; Romanofsky, H. J.; Jacobs, S. D.; Lambropoulos, J. C.

    2015-08-19

    The macro-structure of chemical-vapor-deposited (CVD) zinc sulfide (ZnS) substrates is characterizedby cone-like structures that start growing at the early stages of deposition. As deposition progresses,these cones grow larger and reach centimeter size in height and millimeter size in width. It is challengingto polish out these features from the top layer, particularly for the magnetorheological finishing (MRF)process. A conventional MR fluid tends to leave submillimeter surface artifacts on the finished surface,which is a direct result of the cone-like structure. Here we describe the MRF process of polishing four CVD ZnS substrates, manufactured by four differentvendors, with conventional MR fluid at pH 10 and zirconia-coated-CI (carbonyl iron) MR fluids at pH 4, 5,and 6. We report on the surface–texture evolution of the substrates as they were MRF polished with thedifferent fluids. We show that performances of the zirconia-coated-CI MR fluid at pH 4 are significantlyhigher than that of the same fluid at pH levels of 5 and 6 and moderately higher than that of a conventionalMR fluid at pH 10. An improvement in surface–texture variability from part to part was also observedwith the pH 4 MR fluid.

  8. Current Inhalers Deliver Very Small Doses to the Lower Tracheobronchial Airways: Assessment of Healthy and Constricted Lungs

    PubMed Central

    Walenga, Ross L.; Longest, P. Worth

    2015-01-01

    To evaluate the regional delivery of conventional aerosol medications, a new whole-lung computational fluid dynamics (CFD) modeling approach was applied for metered dose inhaler (MDI) and dry powder inhaler (DPI) aerosols delivered to healthy and constricted airways. The CFD approach included complete airways through the third respiratory bifurcation (B3) and applied the new stochastic individual pathway (SIP) modeling technique beyond B3 through the remainder of the conducting airways together with a new model of deposition in the alveolar region. Bronchiolar (B8-B15) deposition fraction (DF) values were low (~1%) for both MDI and DPI aerosols with the healthy geometry, while delivery to the constricted model was even lower, with DF values of 0.89% and 0.81% for the MDI and DPI, respectively. Calculating dose per unit-surface-area for the commercial MDI and DPI products resulted in approximately 10−3 μg/cm2 in the lower tracheobronchial (TB) region of B8-B15 and 10−4 μg/cm2 in the alveolar region. Across the lung, dose per unit-surface-area varied by 2 orders of magnitude, which increased to 4 orders of magnitude when the mouth-throat region was included. The MDI and DPI both provided very low drug dose per unit-surface-area to the small TB and alveolar airways. PMID:26852850

  9. Surface Forces and Interaction Mechanisms of Emulsion Drops and Gas Bubbles in Complex Fluids.

    PubMed

    Xie, Lei; Shi, Chen; Cui, Xin; Zeng, Hongbo

    2017-02-22

    The interactions of emulsion drops and gas bubbles in complex fluids play important roles in a wide range of biological and technological applications, such as programmable drug and gene delivery, emulsion and foam formation, and froth flotation of mineral particles. In this feature article, we have reviewed our recent progress on the quantification of surface forces and interaction mechanisms of gas bubbles and emulsion drops in different material systems by using several complementary techniques, including the drop/bubble probe atomic force microscope (AFM), surface forces apparatus (SFA), and four-roll mill fluidic device. These material systems include the bubble-self-assembled monolayer (SAM), bubble-polymer, bubble-superhydrophobic surface, bubble-mineral, water-in-oil and oil-in-water emulsions with interface-active components in oil production, and oil/water wetting on polyelectrolyte surfaces. The bubble probe AFM combined with reflection interference contrast microscopy (RICM) was applied for the first time to simultaneously quantify the interaction forces and spatiotemporal evolution of a confined thin liquid film between gas bubbles and solid surfaces with varying hydrophobicity. The nanomechanical results have provided useful insights into the fundamental interaction mechanisms (e.g., hydrophobic interaction in aqueous media) at gas/water/solid interfaces, the stabilization/destabilization mechanisms of emulsion drops, and oil/water wetting mechanisms on solid surfaces. A long-range hydrophilic attraction was found between water and polyelectrolyte surfaces in oil, with the strongest attraction for polyzwitterions, contributing to their superior water wettability in oil and self-cleaning capability of oil contamination. Some remaining challenges and future research directions are discussed and provided.

  10. Surface Tension and Viscosity Measurements in Microgravity: Some Results and Fluid Flow Observations during MSL-1

    NASA Technical Reports Server (NTRS)

    Hyer, Robert W.; Trapaga, G.; Flemings, M. C.

    1999-01-01

    The viscosity of a liquid metal was successfully measured for the first time by a containerless method, the oscillating drop technique. This method also provides a means to obtain a precise, non-contact measurement of the surface tension of the droplet. This technique involves exciting the surface of the molten sample and then measuring the resulting oscillations; the natural frequency of the oscillating sample is determined by its surface tension, and the damping of the oscillations by the viscosity. These measurements were performed in TEMPUS, a microgravity electromagnetic levitator (EML), on the Space Shuttle as a part of the First Microgravity Science Laboratory (MSL-1), which flew in April and July 1997 (STS-83 and STS-94). Some results of the surface tension and viscosity measurements are presented for Pd82Si18. Some observations of the fluid dynamic characteristics (dominant flow patterns, turbulent transition, cavitation, etc.) of levitated droplets are presented and discussed together with magnetohydrodynamic calculations, which were performed to justify these findings.

  11. On the mechanical interaction between a fluid-filled fracture and the earth's surface

    USGS Publications Warehouse

    Pollard, D.D.; Holzhausen, G.

    1979-01-01

    The mechanical interaction between a fluid-filled fracture (e.g., hydraulic fracture joint, or igneous dike) and the earth's surface is analyzed using a two-dimensional elastic solution for a slit of arbitrary inclination buried beneath a horizontal free surface and subjected to an arbitrary pressure distribution. The solution is obtained by iteratively superimposing two fundamental sets of analytical solutions. For uniform internal pressure the slit behaves essentially as if it were in an infinite region if the depth-to-center is three times greater than the half-length. For shallower slits interaction with the free surface is pronounced: stresses and displacements near the slit differ by more than 10% from values for the deeply buried slit. The following changes are noted as the depth-to-center decreases: 1. (1) the mode I stress intensity factor increases for both ends of the slit, but more rapidly at the upper end; 2. (2) the mode II stress-intensity factor is significantly different from zero (except for vertical slits) suggesting propagation out of the original plane of the slit; 3. (3) displacements of the slit wall are asymmetric such that the slit gaps open more widely near the upper end. Similar changes are noted if fluid density creates a linear pressure gradient that is smaller than the lithostatic gradient. Under such conditions natural fractures should propagate preferentially upward toward the earth's surface requiring less pressure as they grow in length. If deformation near the surface is of interest, the model should account explicitly for the free surface. Stresses and displacements at the free surface are not approximated very well by values calculated along a line in an infinite region, even when the slit is far from the line. As depth-to-center of a shallow pressurized slit decreases, the following changes are noted: 1. (1) displacements of the free surface increase to the same order of magnitude as the displacements of the slit walls, 2. (2

  12. Wave propagation in fluid-conveying viscoelastic single-walled carbon nanotubes with surface and nonlocal effects

    NASA Astrophysics Data System (ADS)

    Zhen, Ya-Xin

    2017-02-01

    In this paper, the transverse wave propagation in fluid-conveying viscoelastic single-walled carbon nanotubes is investigated based on nonlocal elasticity theory with consideration of surface effect. The governing equation is formulated utilizing nonlocal Euler-Bernoulli beam theory and Kelvin-Voigt model. Explicit wave dispersion relation is developed and wave phase velocities and frequencies are obtained. The effect of the fluid flow velocity, structural damping, surface effect, small scale effects and tube diameter on the wave propagation properties are discussed with different wave numbers. The wave frequency increases with the increase of fluid flow velocity, but decreases with the increases of tube diameter and wave number. The effect of surface elasticity and residual surface tension is more significant for small wave number and tube diameter. For larger values of wave number and nonlocal parameters, the real part of frequency ratio raises.

  13. Surface chemistry regulates the sensitivity and tolerability of osteoblasts to various magnitudes of fluid shear stress.

    PubMed

    Li, Yan; Wang, Jinfeng; Xing, Juan; Wang, Yuanliang; Luo, Yanfeng

    2016-12-01

    Scaffolds provide a physical support for osteoblasts and act as the medium to transfer mechanical stimuli to cells. To verify our hypothesis that the surface chemistry of scaffolds regulates the perception of cells to mechanical stimuli, the sensitivity and tolerability of osteoblasts to fluid shear stress (FSS) of various magnitudes (5, 12, 20 dynes/cm(2) ) were investigated on various surface chemistries (-OH, -CH3 , -NH2 ), and their follow-up effects on cell proliferation and differentiation were examined as well. The sensitivity was characterized by the release of adenosine triphosphate (ATP), nitric oxide (NO) and prostaglandin E2 (PGE2 ) while the tolerability was by cellular membrane integrity. The cell proliferation was characterized by S-phase cell fraction and the differentiation by ALP activity and ECM expression (fibronectin and type I collagen). As revealed, osteoblasts demonstrated higher sensitivity and lower tolerability on OH and CH3 surfaces, yet lower sensitivity and higher tolerability on NH2 surfaces. Observations on the focal adhesion formation, F-actin organization and cellular orientation before and after FSS exposure suggest that the potential mechanism lies in the differential control of F-actin organization and focal adhesion formation by surface chemistry, which further divergently mediates the sensitivity and tolerability of ROBs to FSS and the follow-up cell proliferation and differentiation. These findings are essentially valuable for design/selection of desirable surface chemistry to orchestrate with FSS stimuli, inducing appropriate cell responses and promoting bone formation. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2978-2991, 2016.

  14. Heat transfer at an upstream-facing surface washed by fluid en route to an aperture in the surface

    NASA Astrophysics Data System (ADS)

    Sparrow, E. M.; Gurdal, U.

    1981-05-01

    Forced convection heat transfer coefficients were measured at a plane surface pierced by an aperture (or tube inlet) of diameter (d) into which fluid flows from a large upstream space. Heat transfer effects were confined to a portion of the surface contained within an annulus of outer diameter D which surrounds the aperture. The experiments were carried out for several values of the d/D ratio ranging from 1/6 to 1/14.4, and for each fixed d/D the Reynolds number was varied parameterically over a range that spanned a factor of five. Dimensional analysis led to a Reynolds number involving the rate of mass flow through the aperture and the outer diameter of the thermall active region. The end result of the dimensional analysis indicated that for a fixed Prandtl number, the Nusselt number could depend on both Re and d/D. When the Nusselt number data for all cases were brought together on a single graph which spanned more than a decade in Reynolds number, no dependence on d/D was observed. It was also found that the average rate of heat transfer per unit area drops off sharply as the outer diameter of the thermally active annular region increases.

  15. Organelle Redox of CF and CFTR-Corrected Airway Epithelia

    PubMed Central

    Schwarzer, Christian; Illek, Beate; Suh, Jung H.; Remington, S. James; Fischer, Horst; Machen, Terry E.

    2014-01-01

    In cystic fibrosis reduced CFTR function may alter redox properties of airway epithelial cells. Redox-sensitive GFP (roGFP1) and imaging microscopy were used to measure redox potentials of cytosol, ER, mitochondria and cell surface of cystic fibrosis nasal epithelial cells and CFTR-corrected cells. We also measured glutathione and cysteine thiol redox states in cell lysates and apical fluids to provide coverage over a range of redox potentials and environments that might be affected by CFTR. As measured with roGFP1, redox potentials at the cell surface (~ -207 ±8 mV) and in the ER (~ -217 ±1 mV) and rates of regulation of the apical fluid and ER lumen following DTT treatment were similar for CF and CFTR-corrected cells. CF and CFTR-corrected cells had similar redox potentials in mitochondria (-344 ±9 mV) and cytosol (-322 ±7 mV). Oxidation of carboxy-dichlorodihydrofluoresceindiacetate and of apical Amplex Red occurred at equal rates in CF and CFTR-corrected cells. Glutathione and cysteine redox couples in cell lysates and apical fluid were equal in CF and CFTR-corrected cells. These quantitative estimates of organelle redox potentials combined with apical and cell measurements using small molecule couples confirmed there were no differences in redox properties of CF and CFTR-corrected cells. PMID:17603939

  16. Polydimethylsiloxane-LiNbO3 surface acoustic wave micropump devices for fluid control into microchannels.

    PubMed

    Girardo, Salvatore; Cecchini, Marco; Beltram, Fabio; Cingolani, Roberto; Pisignano, Dario

    2008-09-01

    This paper presents prototypical microfluidic devices made by hybrid microchannels based on piezoelectric LiNbO(3) and polydimethylsiloxane. This system enables withdrawing micropumping by acoustic radiation in microchannels. The withdrawing configuration, integrated on chip, is here quantitatively investigated for the first time, and found to be related to the formation and coalescence dynamics of droplets within the microchannel, primed by surface acoustic waves. The growth dynamics of droplets is governed by the water diffusion on LiNbO(3), determining the advancement of the fluid front. Observed velocities are up to 2.6 mm s(-1) for 30 dBm signals applied to the interdigital transducer, corresponding to tens of nl s(-1), and the micropumping dynamics is described by a model taking into account an acoustic power exponentially decaying upon travelling along the microchannel. This straighforward and flexible micropumping approach is particularly promising for the withdrawing of liquids in lab-on-chip devices performing cycling transport of fluids and biochemical reactions.

  17. Surface Patterning: Controlling Fluid Flow Through Dolphin and Shark Skin Biomimicry

    NASA Astrophysics Data System (ADS)

    Gamble, Lawren; Lang, Amy; Bradshaw, Michael; McVay, Eric

    2013-11-01

    Dolphin skin is characterized by circumferential ridges, perpendicular to fluid flow, present from the crest of the head until the tail fluke. When observing a cross section of skin, the ridges have a sinusoidal pattern. Sinusoidal grooves have been proven to induce vortices in the cavities that can help control flow separation which can reduce pressure drag. Shark skin, however, is patterned with flexible scales that bristle up to 50 degrees with reversed flow. Both dolphin ridges and shark scales are thought to help control fluid flow and increase swimming efficiency by delaying the separation of the boundary layer. This study investigates how flow characteristics can be altered with bio-inspired surface patterning. A NACA 4412 hydrofoil was entirely patterned with transverse sinusoidal grooves, inspired by dolphin skin but scaled so the cavities on the model have the same Reynolds number as the cavities on a swimming shark. Static tests were conducted at a Reynolds number of approximately 100,000 and at varying angles of attack. The results were compared to the smooth hydrofoil case. The flow data was quantified using Digital Particle Image Velocimetry (DPIV). The results of this study demonstrated that the patterned hydrofoil experienced greater separation than the smooth hydrofoil. It is hypothesize that this could be remediated if the pattern was placed only after the maximum thickness of the hydrofoil. Funding through NSF REU grant 1062611 is gratefully acknowledged.

  18. Surface Enhanced Raman Spectroscopy on Carbonate Fluids at High Pressures: A New Technique to Study Fluid Species Under Geologically Relevant Conditions

    NASA Astrophysics Data System (ADS)

    Chopelas, A.; Black, J. R.; Kavner, A.; Manning, C. E.

    2010-12-01

    The physical and chemical behavior of fluid/mineral interfaces at high pressures and temperatures help govern the generation of magmas, the evolution of the continental crust, and the storage and cycling of volatiles such as water and carbon in and through the Earth’s crust and mantle reservoirs. Little is known of the speciation of silica- and oxidized carbon- bearing fluids at relevant conditions of pressure, temperature and concentration. Currently, our high pressure P/high temperature T Raman spectroscopy studies in the hydrothermal DAC have yielded promising insights into P,T dependence of carbon/bicarbonate speciation. However, due to the low intensity of Raman scattering, results can only be obtained on fluids with carbon species concentrations that are unreasonably high compared with actual geological fluids. To help examine the chemistry of geological fluids at relevant concentrations and P-T conditions, we are developing a technique known as Surface Enhanced Raman Spectroscopy (SERS) in the hydrothermal diamond anvil cell. SERS is a resonant Raman phenomenon yielding potentially large enhancements in spectroscopic signal for Raman-active species adsorbed on nano-structured metals. Currently, this technique is widely used in the chemistry community, and has been mostly been devoted to studying organic materials, including proteins, aromatics, etc, and fluid-nanoparticle interactions. Enhancements in Raman signal of a few orders of magnitude are typical. Here, we show our SERS results on dilute carbonate/bicarbonate solutions at ambient conditions, and at high pressures in the diamond anvil cell. We obtained ambient pressure SERS signal for a dilute 0.02 M bicarbonate/carbonate fluid, using Au, Ag, and Cu as nanoparticle substrates. In the diamond cell, we obtained SERS spectra on a ~0.1 M bicarbonate solution at pressures ranging from 1 GPa to 3 GPa. The SERS spectra revealed the same sequence carbonate/bicarbonate transformations we observed at higher

  19. Effectiveness of surface enhanced Raman spectroscopy of tear fluid with soft substrate for point-of-care therapeutic drug monitoring

    NASA Astrophysics Data System (ADS)

    Yamada, K.; Endo, T.; Imai, H.; Kido, M.; Jeong, H.; Ohno, Y.

    2016-03-01

    We have developed the point-of-care therapeutic drug monitoring kit based on Raman Spectroscopy of tear fluid. In this study, we were examined a soft substrate for an optimal lattice based on nanoimprint lithography using cyclo-olefin polymer to improve the sensitivity for measuring drug concentration in tear fluid. This is photonics crystal which is one of the nano-photonics based device was fabricated. Target is Sodium Phenobarbital which is an anticonvulsant agent. We show the effectiveness of Surface Enhanced Raman Spectroscopy of tear fluid with soft substrate for point-of-care therapeutic drug monitoring.

  20. Computational Fluid Dynamics Simulation of Flows in an Oxidation Ditch Driven by a New Surface Aerator.

    PubMed

    Huang, Weidong; Li, Kun; Wang, Gan; Wang, Yingzhe

    2013-11-01

    In this article, we present a newly designed inverse umbrella surface aerator, and tested its performance in driving flow of an oxidation ditch. Results show that it has a better performance in driving the oxidation ditch than the original one with higher average velocity and more uniform flow field. We also present a computational fluid dynamics model for predicting the flow field in an oxidation ditch driven by a surface aerator. The improved momentum source term approach to simulate the flow field of the oxidation ditch driven by an inverse umbrella surface aerator was developed and validated through experiments. Four kinds of turbulent models were investigated with the approach, including the standard k-ɛ model, RNG k-ɛ model, realizable k-ɛ model, and Reynolds stress model, and the predicted data were compared with those calculated with the multiple rotating reference frame approach (MRF) and sliding mesh approach (SM). Results of the momentum source term approach are in good agreement with the experimental data, and its prediction accuracy is better than MRF, close to SM. It is also found that the momentum source term approach has lower computational expenses, is simpler to preprocess, and is easier to use.

  1. Dependence of ion concentration in simulated body fluid on apatite precipitation on titania surface

    NASA Astrophysics Data System (ADS)

    Sakaguchi, Akira; Nakano, Masayuki; Hieda, Junko; Ohtake, Naoto; Akasaka, Hiroki

    2015-08-01

    Titanium and its alloys are used as biomaterials, because of their high biocompatibility. Apatite precipitates on a titania surface in vivo, and living bone and titanium alloy are coupled through the thin apatite layer. The initial precipitation behavior of apatite on titania in simulated body fluid (SBF) solutions was evaluated and the effect of inorganic ions in the SBF was investigated. Measurement using the SPR phenomenon was used to evaluate the initial apatite precipitation. An SBF containing approximately equal ion concentrations to those in blood plasma was added to a titania surface and the SPR profile was obtained, from which the initial apatite precipitation rate was found to be 1.14 nm/h. Furthermore, the relationship between the inorganic concentration and the precipitation rate was determined for SBFs with different Na+ and Ca2+ concentrations. Apatite precipitation did not occur in the SBF with a low Na+ concentration, whereas the initial apatite precipitation rate in the SBF that did not contain Ca2+ was 0.32 nm/h. According to these results, Ca2+ has little effect on the initial apatite precipitation. In the initial reaction of apatite precipitation, sodium titanate is formed by the absorption of Na+. Next, calcium titanate precipitates upon the substitution of Na+ with Ca2+. Finally, Na+, phosphate ions and hydroxyl ions are attracted to the surface and apatite is formed. Thus, the rate-limiting factor in the initial nucleation of apatite is the Na+ concentration.

  2. Human airway ciliary dynamics

    PubMed Central

    Thompson, Kristin; Knowles, Michael R.; Davis, C. William

    2013-01-01

    Airway cilia depend on precise changes in shape to transport the mucus gel overlying mucosal surfaces. The ciliary motion can be recorded in several planes using video microscopy. However, cilia are densely packed, and automated computerized systems are not available to convert these ciliary shape changes into forms that are useful for testing theoretical models of ciliary function. We developed a system for converting planar ciliary motions recorded by video microscopy into an empirical quantitative model, which is easy to use in validating mathematical models, or in examining ciliary function, e.g., in primary ciliary dyskinesia (PCD). The system we developed allows the manipulation of a model cilium superimposed over a video of beating cilia. Data were analyzed to determine shear angles and velocity vectors of points along the cilium. Extracted waveforms were used to construct a composite waveform, which could be used as a standard. Variability was measured as the mean difference in position of points on individual waveforms and the standard. The shapes analyzed were the end-recovery, end-effective, and fastest moving effective and recovery with mean (± SE) differences of 0.31(0.04), 0.25(0.06), 0.50(0.12), 0.50(0.10), μm, respectively. In contrast, the same measures for three different PCD waveforms had values far outside this range. PMID:23144323

  3. Cold weather exercise and airway cytokine expression.

    PubMed

    Davis, Michael S; Malayer, Jerry R; Vandeventer, Lori; Royer, Christopher M; McKenzie, Erica C; Williamson, Katherine K

    2005-06-01

    Athletes who perform repeated exercise while breathing cold air have a high prevalence of asthmalike chronic airway disease, but the mechanism linking such activity to airway inflammation is unknown. We used a novel animal model (exercising horses) to test the hypothesis that exercise-induced chronic airway disease is caused by exposure of intrapulmonary airways to unconditioned air, resulting in the upregulation of cytokine expression. Bronchoalveolar lavage fluid (BALF) was obtained from eight horses 5 h after submaximal exercise while they breathed room temperature or subfreezing air in a random crossover design. BALF total and differential nucleated cell counts were determined, and relative cytokine mRNA expression in BALF nucleated cells was quantified by real-time RT-PCR using primer and probe sequences specific for equine targets. There were no significant changes in total or differential cell concentrations between BALF recovered after warm and cold air exercise, although there was a strong trend toward increased concentrations of airway epithelial cells after cold air exercise (P = 0.0625). T(H)2 cytokines IL-4, IL-5, and IL-10 were preferentially upregulated after cold air exercise 12-, 9-, and 10-fold, respectively, compared with warm air exercise. Other cytokines (IL-2 and IL-6) were upregulated to a lesser extent (6- and 3-fold, respectively) or not at all (IL-1, IL-8, IFN-gamma, and TNF-alpha). These results suggest that cold weather exercise can lead to asthmalike airway disease through the local induction of cytokines typical of the T(H)2 phenotype.

  4. Quantitative imaging of airway liquid absorption in cystic fibrosis.

    PubMed

    Locke, Landon W; Myerburg, Michael M; Markovetz, Matthew R; Parker, Robert S; Weber, Lawrence; Czachowski, Michael R; Harding, Thomas J; Brown, Stefanie L; Nero, Joseph A; Pilewski, Joseph M; Corcoran, Timothy E

    2014-09-01

    New measures are needed to rapidly assess emerging treatments for cystic fibrosis (CF) lung disease. Using an imaging approach, we evaluated the absorptive clearance of the radiolabeled small molecule probe diethylene triamine penta-acetic acid (DTPA) as an in vivo indicator of changes in airway liquid absorption. DTPA absorption and mucociliary clearance rates were measured in 21 patients with CF (12 adults and nine children) and nine adult controls using nuclear imaging. The effect of hypertonic saline on DTPA absorption was also studied. In addition, in vitro studies were conducted to identify the determinants of transepithelial DTPA absorption. CF patients had significantly increased rates of DTPA absorption compared with control subjects but had similar mucociliary clearance rates. Treatment with hypertonic saline resulted in a decrease in DTPA absorption and an increase in mucociliary clearance in 11 out of 11 adult CF patients compared with treatment with isotonic saline. In vitro studies revealed that ∼ 50% of DTPA absorption can be attributed to transepithelial fluid transport. Apically applied mucus impedes liquid and DTPA absorption. However, mucus effects become negligible in the presence of an osmotic stimulus. Functional imaging of DTPA absorption provides a quantifiable marker of immediate response to treatments that promote airway surface liquid hydration.

  5. Experimental measurement of dynamic fluid shear stress on the ventricular surface of the aortic valve leaflet

    PubMed Central

    Yap, Choon Hwai; Saikrishnan, Neelakantan

    2015-01-01

    Aortic valve (AV) calcification is a highly prevalent disease with serious impact on mortality and morbidity. The exact causes and mechanisms of AV calcification are unclear, although previous studies suggest that mechanical forces play a role. It has been clinically demonstrated that calcification preferentially occurs on the aortic surface of the AV. This is hypothesized to be due to differences in the mechanical environments on the two sides of the valve. It is thus necessary to characterize fluid shear forces acting on both sides of the leaflet to test this hypothesis. The current study is one of two studies characterizing dynamic shear stress on both sides of the AV leaflets. In the current study, shear stresses on the ventricular surface of the AV leaflets were measured experimentally on two prosthetic AV models with transparent leaflets in an in vitro pulsatile flow loop using two-component Laser Doppler Velocimetry (LDV). Experimental measurements were utilized to validate a theoretical model of AV ventricular surface shear stress based on the Womersley profile in a straight tube, with corrections for the opening angle of the valve leaflets. This theoretical model was applied to in vivo data based on MRI-derived volumetric flow rates and valve dimension obtained from the literature. Experimental results showed that ventricular surface shear stress was dominated by the streamwise component. The systolic shear stress waveform resembled a half-sinusoid during systole and peaks at 64–71 dyn/cm2, and reversed in direction at the end of systole for 15–25 ms, and reached a significant negative magnitude of 40–51 dyn/cm2. Shear stresses from the theoretical model applied to in vivo data showed that shear stresses peaked at 77–92 dyn/cm2 and reversed in direction for substantial period of time (108–110 ms) during late systole with peak negative shear stress of 35–38 dyn/cm2. PMID:21465260

  6. Acid-Sensing Ion Channel 1a Contributes to Airway Hyperreactivity in Mice

    PubMed Central

    Reznikov, Leah R.; Meyerholz, David K.; Adam, Ryan J.; Abou Alaiwa, Mahmoud; Jaffer, Omar; Michalski, Andrew S.; Powers, Linda S.; Price, Margaret P.; Stoltz, David A.; Welsh, Michael J.

    2016-01-01

    Neurons innervating the airways contribute to airway hyperreactivity (AHR), a hallmark feature of asthma. Several observations suggested that acid-sensing ion channels (ASICs), neuronal cation channels activated by protons, might contribute to AHR. For example, ASICs are found in vagal sensory neurons that innervate airways, and asthmatic airways can become acidic. Moreover, airway acidification activates ASIC currents and depolarizes neurons innervating airways. We found ASIC1a protein in vagal ganglia neurons, but not airway epithelium or smooth muscle. We induced AHR by sensitizing mice to ovalbumin and found that ASIC1a-/- mice failed to exhibit AHR despite a robust inflammatory response. Loss of ASIC1a also decreased bronchoalveolar lavage fluid levels of substance P, a sensory neuropeptide secreted from vagal sensory neurons that contributes to AHR. These findings suggest that ASIC1a is an important mediator of AHR and raise the possibility that inhibiting ASIC channels might be beneficial in asthma. PMID:27820848

  7. Computational fluid dynamic modeling of a medium-sized surface mine blasthole drill shroud

    PubMed Central

    Zheng, Y.; Reed, W.R.; Zhou, L.; Rider, J.P.

    2016-01-01

    The Pittsburgh Mining Research Division of the U.S. National Institute for Occupational Safety and Health (NIOSH) recently developed a series of models using computational fluid dynamics (CFD) to study airflows and respirable dust distribution associated with a medium-sized surface blasthole drill shroud with a dry dust collector system. Previously run experiments conducted in NIOSH’s full-scale drill shroud laboratory were used to validate the models. The setup values in the CFD models were calculated from experimental data obtained from the drill shroud laboratory and measurements of test material particle size. Subsequent simulation results were compared with the experimental data for several test scenarios, including 0.14 m3/s (300 cfm) and 0.24 m3/s (500 cfm) bailing airflow with 2:1, 3:1 and 4:1 dust collector-to-bailing airflow ratios. For the 2:1 and 3:1 ratios, the calculated dust concentrations from the CFD models were within the 95 percent confidence intervals of the experimental data. This paper describes the methodology used to develop the CFD models, to calculate the model input and to validate the models based on the experimental data. Problem regions were identified and revealed by the study. The simulation results could be used for future development of dust control methods for a surface mine blasthole drill shroud. PMID:27932851

  8. Surface scanning through a cylindrical tank of coupling fluid for clinical microwave breast imaging exams

    SciTech Connect

    Pallone, Matthew J.; Meaney, Paul M.; Paulsen, Keith D.

    2012-06-15

    Purpose: Microwave tomographic image quality can be improved significantly with prior knowledge of the breast surface geometry. The authors have developed a novel laser scanning system capable of accurately recovering surface renderings of breast-shaped phantoms immersed within a cylindrical tank of coupling fluid which resides completely external to the tank (and the aqueous environment) and overcomes the challenges associated with the optical distortions caused by refraction from the air, tank wall, and liquid bath interfaces. Methods: The scanner utilizes two laser line generators and a small CCD camera mounted concentrically on a rotating gantry about the microwave imaging tank. Various calibration methods were considered for optimizing the accuracy of the scanner in the presence of the optical distortions including traditional ray tracing and image registration approaches. In this paper, the authors describe the construction and operation of the laser scanner, compare the efficacy of several calibration methods-including analytical ray tracing and piecewise linear, polynomial, locally weighted mean, and thin-plate-spline (TPS) image registrations-and report outcomes from preliminary phantom experiments. Results: The results show that errors in calibrating camera angles and position prevented analytical ray tracing from achieving submillimeter accuracy in the surface renderings obtained from our scanner configuration. Conversely, calibration by image registration reliably attained mean surface errors of less than 0.5 mm depending on the geometric complexity of the object scanned. While each of the image registration approaches outperformed the ray tracing strategy, the authors found global polynomial methods produced the best compromise between average surface error and scanner robustness. Conclusions: The laser scanning system provides a fast and accurate method of three dimensional surface capture in the aqueous environment commonly found in microwave breast

  9. Surface scanning through a cylindrical tank of coupling fluid for clinical microwave breast imaging exams

    PubMed Central

    Pallone, Matthew J.; Meaney, Paul M.; Paulsen, Keith D.

    2012-01-01

    Purpose: Microwave tomographic image quality can be improved significantly with prior knowledge of the breast surface geometry. The authors have developed a novel laser scanning system capable of accurately recovering surface renderings of breast-shaped phantoms immersed within a cylindrical tank of coupling fluid which resides completely external to the tank (and the aqueous environment) and overcomes the challenges associated with the optical distortions caused by refraction from the air, tank wall, and liquid bath interfaces. Methods: The scanner utilizes two laser line generators and a small CCD camera mounted concentrically on a rotating gantry about the microwave imaging tank. Various calibration methods were considered for optimizing the accuracy of the scanner in the presence of the optical distortions including traditional ray tracing and image registration approaches. In this paper, the authors describe the construction and operation of the laser scanner, compare the efficacy of several calibration methods—including analytical ray tracing and piecewise linear, polynomial, locally weighted mean, and thin-plate-spline (TPS) image registrations—and report outcomes from preliminary phantom experiments. Results: The results show that errors in calibrating camera angles and position prevented analytical ray tracing from achieving submillimeter accuracy in the surface renderings obtained from our scanner configuration. Conversely, calibration by image registration reliably attained mean surface errors of less than 0.5 mm depending on the geometric complexity of the object scanned. While each of the image registration approaches outperformed the ray tracing strategy, the authors found global polynomial methods produced the best compromise between average surface error and scanner robustness. Conclusions: The laser scanning system provides a fast and accurate method of three dimensional surface capture in the aqueous environment commonly found in microwave

  10. Estimation of the reactive mineral surface area during CO2-rich fluid-rock interaction: the influence of neogenic phases

    NASA Astrophysics Data System (ADS)

    Scislewski, A.; Zuddas, P.

    2010-12-01

    Mineral dissolution and precipitation reactions actively participate to control fluid chemistry during water-rock interaction. It is however, difficult to estimate and well normalize bulk reaction rates if the mineral surface area exposed to the aqueous solution and effectively participating on the reactions is unknown. We evaluated the changing of the reactive mineral surface area during the interaction between CO2-rich fluids and Albitite/Granitoid rocks (similar mineralogy but different abundances), reacting under flow-through conditions. Our methodology, adopting an inverse modeling approach, is based on the estimation of dissolution rate and reactive surface area of the different minerals participating in the reactions by the reconstruction the chemical evolution of the interacting fluids. The irreversible mass-transfer processes is defined by a fractional degree of advancement, while calculations were carried out for Albite, Microcline, Biotite and Calcite assuming that the ion activity of dissolved silica and aluminium ions was limited by the equilibrium with quartz and kaolinite. Irrespective of the mineral abundance in granite and albitite, we found that mineral dissolution rates did not change significantly in the investigated range of time where output solution’s pH remained in the range between 6 and 8, indicating that the observed variation in fluid composition depends not on pH but rather on the variation of the parent mineral’s reactive surface area. We found that the reactive surface area of Albite varied by more than 2 orders of magnitude, while Microcline, Calcite and Biotite surface areas changed by 1-2 orders of magnitude. We propose that parent mineral chemical heterogeneity and, particularly, the stability of secondary mineral phases may explain the observed variation of the reactive surface area of the minerals. Formation of coatings at the dissolving parent mineral surfaces significantly reduced the amount of surface available to react

  11. The role bronchoscopy in the diagnosis of airway disease in children

    PubMed Central

    Soyer, Tutku

    2016-01-01

    Bronchoscopy is endoscopic examination of airways that allows both diagnostic and interventional procedures in the evaluation of airway disease in children. It can be performed with either rigid or flexible instruments, depending on the particular needs of patients and skills of bronchoscopist. In addition to visualization of airways, bronchoscopy enables to obtain specimens from lungs and distal airways. Bronchoalveolar lavage (BAL) yields samples from surfaces of the alveoli and aids differential diagnosis of various pulmonary disease. Foreign body removal and examination of anatomy and dynamics of airways are also common indications of bronchoscopy in children. Improvement in the technology, endoscopic instrumentation allows detailed evaluation and interventional manipulation of airway lesions in small children. Although bronchoscopy is considered as a safe procedure, obstruction of airway may challenge and require special endoscopic skills with appropriate instrumentation. This review is aimed to outline the role of bronchoscopy in diagnosis airway disease in children. PMID:28066622

  12. Numerical Simulation of MHD Hiemenz Flow of a Micropolar Fluid towards a Nonlinear Stretching Surface through a Porous Medium

    NASA Astrophysics Data System (ADS)

    Sharma, Rajesh; Bhargava, Rama

    2015-07-01

    In this article, the two-dimensional boundary layer problem of Hiemenz flow (two-dimensional flow of a fluid near a stagnation point) of an incompressible micropolar fluid towards a nonlinear stretching surface placed in a porous medium in the presence of transverse magnetic field is examined. The resulting nonlinear differential equations governing the problem have been transformed by a similarity transformation into a system of nonlinear ordinary differential equations which are solved numerically by the Element Free Galerkin method. The influence of various parameters on the velocity, microrotation, temperature, and concentration is shown. Some of the results are compared with the Finite Element Method. Finally, validation of the numerical results is demonstrated for local skin friction ? for hydrodynamic micropolar fluid flow on a linearly stretching surface.

  13. Respiratory fluid mechanics

    NASA Astrophysics Data System (ADS)

    Grotberg, James B.

    2011-02-01

    This article covers several aspects of respiratory fluid mechanics that have been actively investigated by our group over the years. For the most part, the topics involve two-phase flows in the respiratory system with applications to normal and diseased lungs, as well as therapeutic interventions. Specifically, the topics include liquid plug flow in airways and at airway bifurcations as it relates to surfactant, drug, gene, or stem cell delivery into the lung; liquid plug rupture and its damaging effects on underlying airway epithelial cells as well as a source of crackling sounds in the lung; airway closure from "capillary-elastic instabilities," as well as nonlinear stabilization from oscillatory core flow which we call the "oscillating butter knife;" liquid film, and surfactant dynamics in an oscillating alveolus and the steady streaming, and surfactant spreading on thin viscous films including our discovery of the Grotberg-Borgas-Gaver shock.

  14. Respiratory fluid mechanics

    PubMed Central

    Grotberg, James B.

    2011-01-01

    This article covers several aspects of respiratory fluid mechanics that have been actively investigated by our group over the years. For the most part, the topics involve two-phase flows in the respiratory system with applications to normal and diseased lungs, as well as therapeutic interventions. Specifically, the topics include liquid plug flow in airways and at airway bifurcations as it relates to surfactant, drug, gene, or stem cell delivery into the lung; liquid plug rupture and its damaging effects on underlying airway epithelial cells as well as a source of crackling sounds in the lung; airway closure from “capillary-elastic instabilities,” as well as nonlinear stabilization from oscillatory core flow which we call the “oscillating butter knife;” liquid film, and surfactant dynamics in an oscillating alveolus and the steady streaming, and surfactant spreading on thin viscous films including our discovery of the Grotberg–Borgas–Gaver shock. PMID:21403768

  15. Respiratory fluid mechanics.

    PubMed

    Grotberg, James B

    2011-02-01

    This article covers several aspects of respiratory fluid mechanics that have been actively investigated by our group over the years. For the most part, the topics involve two-phase flows in the respiratory system with applications to normal and diseased lungs, as well as therapeutic interventions. Specifically, the topics include liquid plug flow in airways and at airway bifurcations as it relates to surfactant, drug, gene, or stem cell delivery into the lung; liquid plug rupture and its damaging effects on underlying airway epithelial cells as well as a source of crackling sounds in the lung; airway closure from "capillary-elastic instabilities," as well as nonlinear stabilization from oscillatory core flow which we call the "oscillating butter knife;" liquid film, and surfactant dynamics in an oscillating alveolus and the steady streaming, and surfactant spreading on thin viscous films including our discovery of the Grotberg-Borgas-Gaver shock.

  16. Robust and general method for determining surface fluid flow boundary conditions in articular cartilage contact mechanics modeling.

    PubMed

    Pawaskar, Sainath Shrikant; Fisher, John; Jin, Zhongmin

    2010-03-01

    Contact detection in cartilage contact mechanics is an important feature of any analytical or computational modeling investigation when the biphasic nature of cartilage and the corresponding tribology are taken into account. The fluid flow boundary conditions will change based on whether the surface is in contact or not, which will affect the interstitial fluid pressurization. This in turn will increase or decrease the load sustained by the fluid phase, with a direct effect on friction, wear, and lubrication. In laboratory experiments or clinical hemiarthroplasty, when a rigid indenter or metallic prosthesis is used to apply load to the cartilage, there will not be any fluid flow normal to the surface in the contact region due to the impermeable nature of the indenter/prosthesis. In the natural joint, on the other hand, where two cartilage surfaces interact, flow will depend on the pressure difference across the interface. Furthermore, in both these cases, the fluid would flow freely in non-contacting regions. However, it should be pointed out that the contact area is generally unknown in advance in both cases and can only be determined as part of the solution. In the present finite element study, a general and robust algorithm was proposed to decide nodes in contact on the cartilage surface and, accordingly, impose the fluid flow boundary conditions. The algorithm was first tested for a rigid indenter against cartilage model. The algorithm worked well for two-dimensional four-noded and eight-noded axisymmetric element models as well as three-dimensional models. It was then extended to include two cartilages in contact. The results were in excellent agreement with the previous studies reported in the literature.

  17. A Finite Element Method for Free-Surface Flows of Incompressible Fluids in Three Dimensions, Part II: Dynamic Wetting Lines

    SciTech Connect

    Baer, T.A.; Cairncross, R.A.; Rao, R.R.; Sackinger, P.A.; Schunk, P.R.

    1999-01-29

    To date, few researchers have solved three-dimensional free-surface problems with dynamic wetting lines. This paper extends the free-surface finite element method described in a companion paper [Cairncross, R.A., P.R. Schunk, T.A. Baer, P.A. Sackinger, R.R. Rao, "A finite element method for free surface flows of incompressible fluid in three dimensions, Part I: Boundary-Fitted mesh motion.", to be published (1998)] to handle dynamic wetting. A generalization of the technique used in two dimensional modeling to circumvent double-valued velocities at the wetting line, the so-called kinematic paradox, is presented for a wetting line in three dimensions. This approach requires the fluid velocity normal to the contact line to be zero, the fluid velocity tangent to the contact line to be equal to the tangential component of web velocity, and the fluid velocity into the web to be zero. In addition, slip is allowed in a narrow strip along the substrate surface near the dynamic contact line. For realistic wetting-line motion, a contact angle which varies with wetting speed is required because contact lines in three dimensions typically advance or recede a different rates depending upon location and/or have both advancing and receding portions. The theory is applied to capillary rise of static fluid in a corner, the initial motion of a Newtonian droplet down an inclined plane, and extrusion of a Newtonian fluid from a nozzle onto a moving substrate. The extrusion results are compared to experimental visualization. Subject Categories

  18. Early airway infection, inflammation, and lung function in cystic fibrosis

    PubMed Central

    Nixon, G; Armstrong, D; Carzino, R; Carlin, J; Olinsky, A; Robertson, C; Grimwood, K

    2002-01-01

    Aims: To determine the relation between lower airway infection and inflammation, respiratory symptoms, and lung function in infants and young children with cystic fibrosis (CF). Methods: A prospective study of children with CF aged younger than 3 years, diagnosed by a newborn screening programme. All were clinically stable and had testing as outpatients. Subjects underwent bronchial lavage (BL) and lung function testing by the raised volume rapid thoracoabdominal compression technique under general anaesthesia. BL fluid was cultured and analysed for neutrophil count, interleukin 8, and neutrophil elastase. Lung function was assessed by forced expiratory volume in 0.5, 0.75, and 1 second. Results: Thirty six children with CF were tested on 54 occasions. Lower airway infection shown by BL was associated with a 10% reduction in FEV0.5 compared with subjects without infection. No relation was identified between airway inflammation and lung function. Daily moist cough within the week before testing was reported on 20/54 occasions, but in only seven (35%) was infection detected. Independent of either infection status or airway inflammation, those with daily cough had lower lung function than those without respiratory symptoms at the time of BL (mean adjusted FEV0.5 195 ml and 236 ml respectively). Conclusions: In young children with CF, both respiratory symptoms and airway infection have independent, additive effects on lung function, unrelated to airway inflammation. Further studies are needed to understand the mechanisms of airway obstruction in these young patients. PMID:12244003

  19. Surface structure and biocompatibility of demineralized dentin matrix granules soaked in a simulated body fluid

    NASA Astrophysics Data System (ADS)

    Akazawa, Toshiyuki; Murata, Masaru; Hino, Jun; Nagano, Futami; Shigyo, Tatsuhiro; Nomura, Takafumi; Inano, Hiroyuki; Itabashi, Kohji; Yamagishi, Tohru; Nakamura, Katsuo; Takahashi, Touru; Iida, Shunji; Kashiwazaki, Haruhiko

    2012-12-01

    Demineralized dentin matrix (DDM) granules with excellent biocompatibility were easily prepared using unnecessary human teeth by a new cooling-pulverizing and demineralizing technique. Extracted human teeth were pulverized together with saline ice at 12,000 rpm-rotation number of a ZrO2 blade for 30 s in a ZrO2 vessel. The pulverized granules exhibited the particle size distribution of 0.5-2 mm that was efficient for regeneration of alveolar bone. The (Ca/P) ratios of the granules were 1.60-1.66, which were close to the stoichiometric value of 1.67 for standard hydroxyapatite (HAp). Small amounts of Na+ and Mg2+ ions present at less than 1% were detected. The pulverized granules were dissolved with stirring under 500 rpm for 10-60 min in 2.0%-HNO3 solutions to obtain partial or complete DDM granules. As the dissolution time increased, crystallinity of HAp phase lowered and asperity on surfaces of the granules became outstanding due to elution of mineral components. At the dissolution of 60 min, the pulverizing granules were completely demineralized and the weight decreased to about one-fifth. To improve surface activity of the DDM granules without denaturation of bone growth factors, the DDM granules were soaked at 309.5 K and pH 7.40 in a simulated body fluid (SBF). HAp microcrystals were gradually precipitated on surfaces of the DDM granules with increasing the soaking time. Different morphology of the precipitates was observed, depending on the demineralization situation of the pulverized granules. For the DDM with low dissolution efficiency of 42%, porous bone-like apatites at 24 h after the soaking and fiber-oriented aggregates at 144 h were recognized. The bioactive DDM granules were implanted into the subcutaneous tissues of the back region of rats. At 4 weeks after the implantation, bio-absorption by comparatively small amounts of multi-giant cells was recognized around the surface layers of DDM granules.

  20. Titan's atmosphere and surface liquid: New calculation using Statistical Associating Fluid Theory

    NASA Astrophysics Data System (ADS)

    Tan, Sugata P.; Kargel, Jeffrey S.; Marion, Giles M.

    2013-01-01

    The application of PC-SAFT equation of state (EOS) in analyzing the in situ measurement of atmospheric data by Huygens probe reveals new insights into Titan's atmosphere and surface liquids. The EOS offers the most reliable and accurate calculations in fluid phase equilibria at the cryogenic conditions encountered in Titan and other extra-terrestrial bodies. This paper and a succeeding one pertaining to solid phases are foundational introductions to a new thermodynamics tool (new to planetary science) and will open the way for many diverse planetological applications, but here we limit applications to Titan. Titan's lower stratosphere and lower troposphere are modeled as a well-mixed chemical solution with fixed overall composition of nine components. Using this model in the lower stratosphere, the dew point, below which condensation occurs, is calculated to be at an altitude of 65.3 km (T = 91.3 K, P = 0.031 bar). The first drop of liquid at this point is almost pure propane, which would form a haze (not a dense cloud) due to the minor abundance of this species. Using this model in the lower troposphere, the atmospheric methane mole fractions measured by Huygens probe is well predicted up to an altitude of 29 km, thus validates the model and the EOS. The surface liquid, which is assumed to be in thermodynamic equilibrium with the ground-level atmosphere, is dominated by C2H6, CH4, C3H8, and N2 with mole percents of 53%, 32%, 7%, and 7%, respectively, at a density of 614 kg/m3 in the equator. The effects of the temperature on the surface liquid composition are also discussed. Despite the small surface temperature difference between equatorial and polar regions (3.7 K), the composition of liquid in polar regions is very different from that in the equator: 68% CH4, 22% N2, and 8% C2H6 with the amount of liquid nine times larger than that in the equator at a 10%-smaller density of 551 kg/m3. The system is accurately estimated using the binary of CH4 and N2 only at an

  1. Scanning probe acceleration microscopy (SPAM) in fluids: Mapping mechanical properties of surfaces at the nanoscale

    PubMed Central

    Legleiter, Justin; Park, Matthew; Cusick, Brian; Kowalewski, Tomasz

    2006-01-01

    One of the major thrusts in proximal probe techniques is combination of imaging capabilities with simultaneous measurements of physical properties. In tapping mode atomic force microscopy (TMAFM), the most straightforward way to accomplish this goal is to reconstruct the time-resolved force interaction between the tip and surface. These tip–sample forces can be used to detect interactions (e.g., binding sites) and map material properties with nanoscale spatial resolution. Here, we describe a previously unreported approach, which we refer to as scanning probe acceleration microscopy (SPAM), in which the TMAFM cantilever acts as an accelerometer to extract tip–sample forces during imaging. This method utilizes the second derivative of the deflection signal to recover the tip acceleration trajectory. The challenge in such an approach is that with real, noisy data, the second derivative of the signal is strongly dominated by the noise. This problem is solved by taking advantage of the fact that most of the information about the deflection trajectory is contained in the higher harmonics, making it possible to filter the signal by “comb” filtering, i.e., by taking its Fourier transform and inverting it while selectively retaining only the intensities at integer harmonic frequencies. Such a comb filtering method works particularly well in fluid TMAFM because of the highly distorted character of the deflection signal. Numerical simulations and in situ TMAFM experiments on supported lipid bilayer patches on mica are reported to demonstrate the validity of this approach. PMID:16551751

  2. The self-interaction of a fluid interface, the wavevector dependent surface tension and wedge filling.

    PubMed

    Parry, Andrew O; Rascón, Carlos

    2011-01-12

    We argue that whenever an interface, separating bulk fluid phases, adopts a non-planar configuration (induced by a confining geometry or thermal fluctuations, say), the energy cost of it will contain a non-local self-interaction term. For systems with short-ranged forces and Ising symmetry, we determine the self-interaction by integrating out bulk-like degrees of freedom from a more microscopic Landau-Ginzburg-Wilson model. The self-interaction can be written in a simple diagrammatic form involving integrals over effective two-body forces acting at the interface and consistently accounts for a number of known features of the microscopic model, including the wavevector dependence of the surface tension describing the fluctuations of a near planar interface. When applied to wedge filling transitions, the self-interaction describes the attraction between the wetting films on either side of the wedge. We show that, for sufficiently acute wedges, this can alter the order of the filling phase transition.

  3. Quantifying the residence time distribution of surface transient storage in streams: A computational fluid dynamics approach

    NASA Astrophysics Data System (ADS)

    Jackson, T. R.; Drost, K. J.; Haggerty, R.; Apte, S. V.

    2011-12-01

    Transient storage is the sum of surface transient storage (STS) and hyporheic transient storage (HTS) and separating the two storage components is challenging. A number of studies have attempted to determine the relationship between transient storage and stream channel properties; however, difficulties ensue when attempting to calculate STS. The present study attempts to develop a predictive relationship between a stream's STS residence time distribution (RTD) to physically-based and field-measureable properties of natural streams. Our approach is to use field measurements to constrain a computational fluid dynamics (CFD) model of STS and use both to develop and test a predictive model of STS RTD. Field sites were located on Oak and Soap creeks in the Willamette Valley near Corvallis, Oregon. Data collection included: (1) obtaining detailed stream and STS zone morphologies through dense survey measurements; (2) determining turbulence parameters and CFD model boundary inputs from stream and storage zone velocity measurements with a Marsh-McBirney and acoustic Doppler velocimeter; (3) quantifying the RTD and its mean using salt tracer injections and electrical conductivity probes; and (4) estimating mixing layer parameters using velocity measurements and a visual dye. Preliminary results from the CFD model and comparison to field data will be presented, and resulting insights into the RTD.

  4. A Global Assessment of Accelerations in Mass Transport of Surface Geophysical Fluid

    NASA Astrophysics Data System (ADS)

    Wu, X.; Heflin, M. B.

    2015-12-01

    Mass transport in the Earth's surface geophysical fluid layer has complex spatiotemporal patterns. The GRACE gravity mission provides an unprecedented global capability to monitor this important process with high accuracy and resolution. Accurate assessments of global mass transport patterns and budget also depend critically on changes in degree-1 coefficients (geocenter motion) and in Earth's dynamic oblateness coefficient J2. We combine GRACE measurements, time series of GNSS data, JPL's ECCO ocean bottom pressure model, and high-resolution loose a priori models of mass variation regimes to derive complete spherical harmonic spectra of detrended mass variations up to degree and order 180. Mass accelerations are estimated along with linear, annual, semiannual, and the 161-day tidal aliasing components from coefficient time series. The appropriateness of a priori information and estimate uncertainties are further evaluated by variance component estimation and residual statistics of fitting the time series. During the GRACE data period of 2002.2-2015.0, accelerations in mass transport are geographically uneven with significant positive or negative accelerations in various parts of the world. While Greenland and West Antarctica show strong accelerated mass losses, Alaska and the Arctic Ocean have significant positive accelerations with reversals of earlier mass loss trends. No evidence of non-Arctic global mean sea level acceleration due to mass has been found. Depending on region, some estimated accelerations are also not steady over time due to large irregular and interannual variations.

  5. Scanning probe acceleration microscopy (SPAM) in fluids: Mapping mechanical properties of surfaces at the nanoscale

    NASA Astrophysics Data System (ADS)

    Legleiter, Justin; Park, Matthew; Cusick, Brian; Kowalewski, Tomasz

    2006-03-01

    One of the major thrusts in proximal probe techniques is combination of imaging capabilities with simultaneous measurements of physical properties. In tapping mode atomic force microscopy (TMAFM), the most straightforward way to accomplish this goal is to reconstruct the time-resolved force interaction between the tip and surface. These tip-sample forces can be used to detect interactions (e.g., binding sites) and map material properties with nanoscale spatial resolution. Here, we describe a previously unreported approach, which we refer to as scanning probe acceleration microscopy (SPAM), in which the TMAFM cantilever acts as an accelerometer to extract tip-sample forces during imaging. This method utilizes the second derivative of the deflection signal to recover the tip acceleration trajectory. The challenge in such an approach is that with real, noisy data, the second derivative of the signal is strongly dominated by the noise. This problem is solved by taking advantage of the fact that most of the information about the deflection trajectory is contained in the higher harmonics, making it possible to filter the signal by “comb” filtering, i.e., by taking its Fourier transform and inverting it while selectively retaining only the intensities at integer harmonic frequencies. Such a comb filtering method works particularly well in fluid TMAFM because of the highly distorted character of the deflection signal. Numerical simulations and in situ TMAFM experiments on supported lipid bilayer patches on mica are reported to demonstrate the validity of this approach.

  6. Scanning probe acceleration microscopy (SPAM) in fluids: mapping mechanical properties of surfaces at the nanoscale.

    PubMed

    Legleiter, Justin; Park, Matthew; Cusick, Brian; Kowalewski, Tomasz

    2006-03-28

    One of the major thrusts in proximal probe techniques is combination of imaging capabilities with simultaneous measurements of physical properties. In tapping mode atomic force microscopy (TMAFM), the most straightforward way to accomplish this goal is to reconstruct the time-resolved force interaction between the tip and surface. These tip-sample forces can be used to detect interactions (e.g., binding sites) and map material properties with nanoscale spatial resolution. Here, we describe a previously unreported approach, which we refer to as scanning probe acceleration microscopy (SPAM), in which the TMAFM cantilever acts as an accelerometer to extract tip-sample forces during imaging. This method utilizes the second derivative of the deflection signal to recover the tip acceleration trajectory. The challenge in such an approach is that with real, noisy data, the second derivative of the signal is strongly dominated by the noise. This problem is solved by taking advantage of the fact that most of the information about the deflection trajectory is contained in the higher harmonics, making it possible to filter the signal by "comb" filtering, i.e., by taking its Fourier transform and inverting it while selectively retaining only the intensities at integer harmonic frequencies. Such a comb filtering method works particularly well in fluid TMAFM because of the highly distorted character of the deflection signal. Numerical simulations and in situ TMAFM experiments on supported lipid bilayer patches on mica are reported to demonstrate the validity of this approach.

  7. Magnetohydrodynamic two-phase dusty fluid flow and heat model over deforming isothermal surfaces

    NASA Astrophysics Data System (ADS)

    Turkyilmazoglu, Mustafa

    2017-01-01

    This paper is devoted to the mathematical analysis of a magnetohydrodynamic viscous two-phase dusty fluid flow and heat transfer over permeable stretching or shrinking bodies. The wall boundary is subjected to a linear deformation as well as to a quadratic surface temperature. Such a highly nonlinear phenomenon, for the first time in the literature, is attacked to search for occurrence of exact solutions, whose numerical correspondences are already available for limited wall transpiration velocities. The obtained analytical solutions are found be in perfect line with the numerical computations. Besides this, exact solutions point to the existence of dual solutions for both permeable stretching and shrinking cases, which were not detected from the numerical studies up to date. The existence of such exact solutions and their parameter domain particularly depending on the wall suction or injection are successfully analyzed. The physical outcomes concerning the effects of suspended particles on the momentum and thermal boundary layers well-documented in the open literature can be best understood from the presented exact solutions.

  8. Spinodal decomposition of a binary magnetic fluid confined to a surface.

    PubMed

    Lichtner, K; Klapp, S H L

    2013-09-01

    In our previous work [J. Chem. Phys. 136, 024502 (2012)], we reported a demixing phase transition of a quasi-two-dimensional, binary Heisenberg fluid mixture driven by the ferromagnetic interactions of the magnetic species. Here, we present a theoretical study for the time-dependent coarsening occurring within the two-phase region in the density-concentration plane, also known as spinodal decomposition. Our investigations are based on dynamical density functional theory (DDFT). The particles in the mixture are modeled as Gaussian soft spheres on a two-dimensional surface, where one component carries a classical spin of Heisenberg type. To investigate the two-phase region, we first present a linear stability analysis with respect to small, harmonic density perturbations. Second, to capture nonlinear effects, we calculate time-dependent structure factors by combining DDFT with Percus' test particle method. For the growth of the average domain size l during spinodal decomposition with time t, we observe a power-law behavior l∝t^{δ_{α}} with δ_{m}≃0.333 for the magnetic species and δ_{n}≃0.323 for the nonmagnetic species.

  9. Determination of glucose in interstitial fluid by surface plasmon resonance biosensor

    NASA Astrophysics Data System (ADS)

    Huang, Fuxiang; Liu, Jin; Yu, Haixia; Zhang, Zengfu; Li, Dachao; Xu, Kexin

    2008-02-01

    The concentration of glucose in interstitial fluid determined by using the surface plasmon resonance (SPR) biosensor with chemical bonding D-Galactose/D-Glucose Binding Protein (GGBP) is proposed in this paper. D-Galactose/D-Glucose Binding Protein (GGBP), a kind of protein which has the ability to absorb the glucose specifically, is immobilized on the gold film of the SPR sensor to improve the sensitivity of glucose detecting. The GGBPs mutated at different points have different association abilities with glucose, which bring different measurement range and precision. So the selection of proteins is a critical problem of the determination of glucose by using SPR biosensor. Using different mutated GGBPs, the samples with different concentrations of glucose are measured in the experiment, and the prediction error and precision are discussed. Furthermore, the light intensity of sensor is instable, so the baseline of SPR responses is tracked and adjusted accordingly using the methods - fixing points and fixing areas' ratio. The experiment results show that GGBPs mutated at different points have its corresponding working curves and different measurement precision. In conclusion, the study is significant for the application of SPR biosensor to the minimally invasive diabetes testing and other detection of human body components.

  10. A surface acoustic wave micropump to pump fluids from a droplet into a closed microchannel using evaporation and capillary effects

    NASA Astrophysics Data System (ADS)

    Zhang, Anliang; Zha, Yan; Zhang, Jiansheng

    2014-12-01

    A new method for converting a microdroplet on a piezoelectric substrate into continuous fluid flow in microchannels is presented. An interdigital transducer with 27.5 MHz center frequency is fabricated on a 1280 yx-LiNbO3 piezoelectric substrate for exciting surface acoustic wave. A PDMS (Polydimethylsiloxane) microchannel is mounted on the piezoelectric substrate. One end of the microchannel is connected with water absorbing paper, while the other end of the microchannel is in touch with a droplet to be converted. The surface acoustic wave is used for controlling the evaporation velocity of the fluid in the microchannel. Part of fluid in the droplet can be entered into the microchannel and transported there due to the evaporation and capillary effects. Red dye solution is used to demonstrate the conversion of the droplet and the transportation of the fluid in the microchannel. Results show that the droplet on the piezoelectric substrate can successfully be converted into continuous fluid. The flow velocity is increased with the power of the electric signal applied to the interdigital transducer. Average flow velocity is 0.0235μl/s when the power of the electric signal is 30.0dBm. The work is helpful for piezoelectric microfluidic devices for biochemical analysis.

  11. Theoretical treatment of the bulk and surface properties of fluids containing long, flexible molecules

    SciTech Connect

    Not Available

    1993-01-01

    Purpose is to develop an equation of state for predicting the thermodynamic properties of fluids containing chain-like molecules ranging from alkanes to polymers. Foundation of this work is the Generalized Flory Dimer (GFD) theory. GFD is extended to square-well chain mixtures. The second virial coefficient has been evaluated for hard-chain and square-well chain fluids using a Monte Carlo approach. The polymer RISM theory was used to determine the segment-segment radial distributrion function for hard chain fluids. Monte Carlo simulations are being performed of the self-diffusion coeffient, shear and longitudinal viscosities, and thermal conductivity for hard chain fluids. (DLC)

  12. Theoretical treatment of the bulk and surface properties of fluids containing long, flexible molecules

    SciTech Connect

    Not Available

    1993-06-01

    Purpose is to develop an equation of state for predicting the thermodynamic properties of fluids containing chain-like molecules ranging from alkanes to polymers. Foundation of this work is the Generalized Flory Dimer (GFD) theory. GFD is extended to square-well chain mixtures. The second virial coefficient has been evaluated for hard-chain and square-well chain fluids using a Monte Carlo approach. The polymer RISM theory was used to determine the segment-segment radial distributrion function for hard chain fluids. Monte Carlo simulations are being performed of the self-diffusion coeffient, shear and longitudinal viscosities, and thermal conductivity for hard chain fluids. (DLC)

  13. Reducing bacterial contamination inside fluid catch bag in 25-gauge vitrectomy by use of 0.25 % povidone-iodine ocular surface irrigation.

    PubMed

    Shimada, Hiroyuki; Nakashizuka, Hiroyuki; Hattori, Takayuki; Kitagawa, Yorihisa; Manabe, Ayumu; Otani, Kuon; Yuzawa, Mitsuko

    2013-02-01

    To examine the bacterial detection rate in infusion fluid collected inside the fluid catch bag during 25-gauge (25G) vitrectomy when the ocular surface was irrigated with infusion fluid or 0.25 % povidone-iodine. Two groups using different fluids for ocular surface irrigation during 25G vitrectomy were studied. Fifty-five consecutive eyes received ocular surface irrigation with infusion fluid (IF group) and 52 consecutive eyes with 0.25 % povidone-iodine (PI group). Samples of ocular surface fluid were collected at the beginning of surgery and samples of infusion fluid inside the fluid catch bag were collected at the end of surgery for bacteriological cultures. At the beginning of surgery, the bacterial detection rates in ocular surface fluid samples were 5.8 % (3 of 52 eyes) in the IF group and 7.7 % (4 of 52 eyes) in the PI group, with no significant difference (P = 0.6955). At the end of surgery, the bacterial detection rates in infusion fluid collected inside the fluid catch bag were 23.1 % (12 of 52 eyes) in the IF group and 3.8 % (2 of 52 eyes) in the PI group, with a significant difference (P = 0.0041). No endophthalmitis occurred in either group. These results demonstrate the risk of bacterial contamination when surgical instruments fall accidentally into the fluid catch bag during conventional 25G vitrectomy. Irrigating the ocular surface with 0.25 % povidone-iodine instead of infusion fluid significantly reduces the bacterial contamination rate in the fluid catch bag.

  14. The Effect of Surface Tension on the Gravity-driven Thin Film Flow of Newtonian and Power-law Fluids.

    PubMed

    Hu, Bin; Kieweg, Sarah L

    2012-07-15

    Gravity-driven thin film flow is of importance in many fields, as well as for the design of polymeric drug delivery vehicles, such as anti-HIV topical microbicides. There have been many prior works on gravity-driven thin films. However, the incorporation of surface tension effect has not been well studied for non-Newtonian fluids. After surface tension effect was incorporated into our 2D (i.e. 1D spreading) power-law model, we found that surface tension effect not only impacted the spreading speed of the microbicide gel, but also had an influence on the shape of the 2D spreading profile. We observed a capillary ridge at the front of the fluid bolus. Previous literature shows that the emergence of a capillary ridge is strongly related to the contact line fingering instability. Fingering instabilities during epithelial coating may change the microbicide gel distribution and therefore impact how well it can protect the epithelium. In this study, we focused on the capillary ridge in 2D flow and performed a series of simulations and showed how the capillary ridge height varies with other parameters, such as surface tension coefficient, inclination angle, initial thickness, and power-law parameters. As shown in our results, we found that capillary ridge height increased with higher surface tension, steeper inclination angle, bigger initial thickness, and more Newtonian fluids. This study provides the initial insights of how to optimize the flow and prevent the appearance of a capillary ridge and fingering instability.

  15. Glutathione redox regulates airway hyperresponsiveness and airway inflammation in mice.

    PubMed

    Koike, Yoko; Hisada, Takeshi; Utsugi, Mitsuyoshi; Ishizuka, Tamotsu; Shimizu, Yasuo; Ono, Akihiro; Murata, Yukie; Hamuro, Junji; Mori, Masatomo; Dobashi, Kunio

    2007-09-01

    Glutathione is the major intracellular redox buffer. We have shown that glutathione redox status, which is the balance between intracellular reduced (GSH) and oxidized (GSSG) glutathione, in antigen-presenting cells (APC) regulates the helper T cell type 1 (Th1)/Th2 balance due to the production of IL-12. Bronchial asthma is a typical Th2 disease. Th2 cells and Th2 cytokines are characteristic of asthma and trigger off an inflammation. Accordingly, we studied the effects of the intracellular glutathione redox status on airway hyperresponsiveness (AHR) and allergen-induced airway inflammation in a mouse model of asthma. We used gamma-Glutamylcysteinylethyl ester (gamma-GCE), which is a membrane-permeating GSH precursor, to elevate the intracellular GSH level and GSH/GSSG ratio of mice. In vitro, gamma-GCE pretreatment of human monocytic THP-1 cells elevated the GSH/GSSG ratio and enhanced IL-12(p70) production induced by LPS. In the mouse asthma model, intraperitoneal injection of gamma-GCE elevated the GSH/GSSG ratio of lung tissue and reduced AHR. gamma-GCE reduced levels of IL-4, IL-5, IL-10, and the chemokines eotaxin and RANTES (regulated on activation, normal T cell expressed and secreted) in bronchoalveolar lavage fluid, whereas it enhanced the production of IL-12 and IFN-gamma. Histologically, gamma-GCE suppressed eosinophils infiltration. Interestingly, we also found that gamma-GCE directly inhibited chemokine-induced eosinophil chemotaxis without affecting eotaxin receptor chemokine receptor 3 (CCR3) expressions. Taken together, these findings suggest that changing glutathione redox balance, increase in GSH level, and the GSH/GSSG ratio by gamma-GCE, ameliorate bronchial asthma by altering the Th1/Th2 imbalance through IL-12 production from APC and suppressing chemokine production and eosinophil migration itself.

  16. A Magnetic-Fluid Seal for Measurement of Aerodynamic Surface Pressure.

    DTIC Science & Technology

    1977-04-01

    A magnetic - fluid sliding seal was designed, fabricated, and tested for application in a special instrumentation arrangement to measure the...spin rates. The effects of certain seal parameters were investigated including: gap distance between stationary and moving components, magnetic ... fluid properties (i.e., magnetization strength and viscosity), and ferrous versus nonferrous moving component material. These tests demonstrated that the

  17. Upper airway radiographs in infants with upper airway insufficiency.

    PubMed Central

    Tonkin, S L; Davis, S L; Gunn, T R

    1994-01-01

    Upper airway measurements in nine infants considered to be at risk of upper airway insufficiency, six of whom presented after an apnoeic episode, were compared with measurements taken in two age groups of healthy infants. Paired, inspiratory and expiratory, lateral upper airway radiographs were obtained while the infants were awake and breathing quietly. The radiographs of all nine infants demonstrated narrowing in the oropharyngeal portion of the airway during inspiration and in six infants there was ballooning of the upper airway during expiration. Seven of the nine infants subsequently experienced recurrent apnoeic episodes which required vigorous stimulation to restore breathing. Experience suggests that respiratory phase timed radiographs are a useful adjunct to the evaluation of infants who are suspected of having upper airway dysfunction. They provide information regarding both the dimensions and compliance of the upper airway as well as the site of any restriction. Images PMID:8048825

  18. Vesicular nucleotide transporter regulates the nucleotide content in airway epithelial mucin granules

    PubMed Central

    Sesma, Juliana I.; Kreda, Silvia M.; Okada, Seiko F.; van Heusden, Catharina; Moussa, Lama; Jones, Lisa C.; O'Neal, Wanda K.; Togawa, Natsuko; Hiasa, Miki; Moriyama, Yoshinori

    2013-01-01

    Nucleotides within the airway surface liquid promote fluid secretion via activation of airway epithelial purinergic receptors. ATP is stored within and released from mucin granules as co-cargo with mucins, but the mechanism by which ATP, and potentially other nucleotides, enter the lumen of mucin granules is not known. We assessed the contribution of the recently identified SLC17A9 vesicle nucleotide transporter (VNUT) to the nucleotide availability within isolated mucin granules and further examined the involvement of VNUT in mucin granule secretion-associated nucleotide release. RT-PCR and Western blot analyses indicated that VNUT is abundantly expressed in airway epithelial goblet-like Calu-3 cells, migrating as a duplex with apparent mobility of 55 and 60 kDa. Subcellular fractionation studies indicated that VNUT55 was associated with high-density mucin granules, whereas VNUT60 was associated with low-density organelles. Immunofluorescence studies showed that recombinant VNUT localized to mucin granules and other organelles. Mucin granules isolated from VNUT short hairpin RNA-expressing cells exhibited a marked reduction of ATP, ADP, AMP, and UTP levels within granules. Ca2+-regulated vesicular ATP release was markedly reduced in these cells, but mucin secretion was not affected. These results suggest that VNUT is the relevant nucleotide transporter responsible for the uptake of cytosolic nucleotides into mucin granules. By controlling the entry of nucleotides into mucin granules, VNUT contributes to the release of purinergic signaling molecules necessary for the proper hydration of co-released mucins. PMID:23467297

  19. Vesicular nucleotide transporter regulates the nucleotide content in airway epithelial mucin granules.

    PubMed

    Sesma, Juliana I; Kreda, Silvia M; Okada, Seiko F; van Heusden, Catharina; Moussa, Lama; Jones, Lisa C; O'Neal, Wanda K; Togawa, Natsuko; Hiasa, Miki; Moriyama, Yoshinori; Lazarowski, Eduardo R

    2013-05-15

    Nucleotides within the airway surface liquid promote fluid secretion via activation of airway epithelial purinergic receptors. ATP is stored within and released from mucin granules as co-cargo with mucins, but the mechanism by which ATP, and potentially other nucleotides, enter the lumen of mucin granules is not known. We assessed the contribution of the recently identified SLC17A9 vesicle nucleotide transporter (VNUT) to the nucleotide availability within isolated mucin granules and further examined the involvement of VNUT in mucin granule secretion-associated nucleotide release. RT-PCR and Western blot analyses indicated that VNUT is abundantly expressed in airway epithelial goblet-like Calu-3 cells, migrating as a duplex with apparent mobility of 55 and 60 kDa. Subcellular fractionation studies indicated that VNUT55 was associated with high-density mucin granules, whereas VNUT60 was associated with low-density organelles. Immunofluorescence studies showed that recombinant VNUT localized to mucin granules and other organelles. Mucin granules isolated from VNUT short hairpin RNA-expressing cells exhibited a marked reduction of ATP, ADP, AMP, and UTP levels within granules. Ca(2+)-regulated vesicular ATP release was markedly reduced in these cells, but mucin secretion was not affected. These results suggest that VNUT is the relevant nucleotide transporter responsible for the uptake of cytosolic nucleotides into mucin granules. By controlling the entry of nucleotides into mucin granules, VNUT contributes to the release of purinergic signaling molecules necessary for the proper hydration of co-released mucins.

  20. Quantitative analysis of airway abnormalities in CT

    NASA Astrophysics Data System (ADS)

    Petersen, Jens; Lo, Pechin; Nielsen, Mads; Edula, Goutham; Ashraf, Haseem; Dirksen, Asger; de Bruijne, Marleen

    2010-03-01

    A coupled surface graph cut algorithm for airway wall segmentation from Computed Tomography (CT) images is presented. Using cost functions that highlight both inner and outer wall borders, the method combines the search for both borders into one graph cut. The proposed method is evaluated on 173 manually segmented images extracted from 15 different subjects and shown to give accurate results, with 37% less errors than the Full Width at Half Maximum (FWHM) algorithm and 62% less than a similar graph cut method without coupled surfaces. Common measures of airway wall thickness such as the Interior Area (IA) and Wall Area percentage (WA%) was measured by the proposed method on a total of 723 CT scans from a lung cancer screening study. These measures were significantly different for participants with Chronic Obstructive Pulmonary Disease (COPD) compared to asymptomatic participants. Furthermore, reproducibility was good as confirmed by repeat scans and the measures correlated well with the outcomes of pulmonary function tests, demonstrating the use of the algorithm as a COPD diagnostic tool. Additionally, a new measure of airway wall thickness is proposed, Normalized Wall Intensity Sum (NWIS). NWIS is shown to correlate better with lung function test values and to be more reproducible than previous measures IA, WA% and airway wall thickness at a lumen perimeter of 10 mm (PI10).

  1. Fluids by design using chaotic surface waves to create a metafluid that is Newtonian, thermal, and entirely tunable

    NASA Astrophysics Data System (ADS)

    Welch, Kyle J.; Liebman-Peláez, Alexander; Corwin, Eric I.

    2016-09-01

    In conventional fluids, viscosity depends on temperature according to a strict relationship. To change this relationship, one must change the molecular nature of the fluid. Here, we create a metafluid whose properties are derived not from the properties of molecules but rather from chaotic waves excited on the surface of vertically agitated water. By making direct rheological measurements of the flow properties of our metafluid, we show that it has independently tunable viscosity and temperature, a quality that no conventional fluid possesses. We go on to show that the metafluid obeys the Einstein relation, which relates many-body response (viscosity) to single-particle dynamics (diffusion) and is a fundamental result in equilibrium thermal systems. Thus, our metafluid is wholly consistent with equilibrium thermal physics, despite being markedly nonequilibrium. Taken together, our results demonstrate a type of material that retains equilibrium physics while simultaneously allowing for direct programmatic control over material properties.

  2. Fluids by design using chaotic surface waves to create a metafluid that is Newtonian, thermal, and entirely tunable

    PubMed Central

    Welch, Kyle J.; Liebman-Peláez, Alexander; Corwin, Eric I.

    2016-01-01

    In conventional fluids, viscosity depends on temperature according to a strict relationship. To change this relationship, one must change the molecular nature of the fluid. Here, we create a metafluid whose properties are derived not from the properties of molecules but rather from chaotic waves excited on the surface of vertically agitated water. By making direct rheological measurements of the flow properties of our metafluid, we show that it has independently tunable viscosity and temperature, a quality that no conventional fluid possesses. We go on to show that the metafluid obeys the Einstein relation, which relates many-body response (viscosity) to single-particle dynamics (diffusion) and is a fundamental result in equilibrium thermal systems. Thus, our metafluid is wholly consistent with equilibrium thermal physics, despite being markedly nonequilibrium. Taken together, our results demonstrate a type of material that retains equilibrium physics while simultaneously allowing for direct programmatic control over material properties. PMID:27621467

  3. MHD Convective Flow of Jeffrey Fluid Due to a Curved Stretching Surface with Homogeneous-Heterogeneous Reactions.

    PubMed

    Imtiaz, Maria; Hayat, Tasawar; Alsaedi, Ahmed

    2016-01-01

    This paper looks at the flow of Jeffrey fluid due to a curved stretching sheet. Effect of homogeneous-heterogeneous reactions is considered. An electrically conducting fluid in the presence of applied magnetic field is considered. Convective boundary conditions model the heat transfer analysis. Transformation method reduces the governing nonlinear partial differential equations into the ordinary differential equations. Convergence of the obtained series solutions is explicitly discussed. Characteristics of sundry parameters on the velocity, temperature and concentration profiles are analyzed by plotting graphs. Computations for pressure, skin friction coefficient and surface heat transfer rate are presented and examined. It is noted that fluid velocity and temperature through curvature parameter are enhanced. Increasing values of Biot number correspond to the enhancement in temperature and Nusselt number.

  4. MHD Convective Flow of Jeffrey Fluid Due to a Curved Stretching Surface with Homogeneous-Heterogeneous Reactions

    PubMed Central

    Imtiaz, Maria; Hayat, Tasawar; Alsaedi, Ahmed

    2016-01-01

    This paper looks at the flow of Jeffrey fluid due to a curved stretching sheet. Effect of homogeneous-heterogeneous reactions is considered. An electrically conducting fluid in the presence of applied magnetic field is considered. Convective boundary conditions model the heat transfer analysis. Transformation method reduces the governing nonlinear partial differential equations into the ordinary differential equations. Convergence of the obtained series solutions is explicitly discussed. Characteristics of sundry parameters on the velocity, temperature and concentration profiles are analyzed by plotting graphs. Computations for pressure, skin friction coefficient and surface heat transfer rate are presented and examined. It is noted that fluid velocity and temperature through curvature parameter are enhanced. Increasing values of Biot number correspond to the enhancement in temperature and Nusselt number. PMID:27583457

  5. The innate immune properties of airway mucosal surfaces are regulated by dynamic interactions between mucins and interacting proteins: the mucin interactome

    PubMed Central

    Ford, Amina A.; Wang, Tiffany; Li, Lily; Kesimer, Mehmet

    2016-01-01

    Summary Chronic lung diseases such as cystic fibrosis, chronic bronchitis and asthma, are characterized by hypersecretion and poor clearance of mucus, which are associated with poor prognosis and mortality. Little is known about the relationship between the biophysical properties of mucus and its molecular composition. The mucins MUC5B and MUC5AC are traditionally believed to generate the characteristic biophysical properties of airway mucus. However, the contribution of hundreds of globular proteins to the biophysical properties of mucus is not clear. Approximately one-third of the total mucus proteome comprises distinct, multi-protein complexes centered around airway mucins. These complexes constitute a discrete entity we call the “mucin interactome”. The data suggest that while the majority of these proteins interact with mucins via electrostatic and weak interactions, some interact through very strong hydrophobic and/or covalent interactions. Using reagents that interfere with protein-protein interactions, the complexes can be disassembled, and mucus rheology can be dramatically altered. Using MUC5B-glutathione S-transferase (GST) and MUC5B-galectin-3 as a representative of these interactions, we provide evidence that individual mucin protein interactions can alter the biophysical properties of mucus and modulate the biological function of the protein. We propose that the key mechano- and bio-active functions of mucus depend on the dynamic interactions between mucins and globular proteins. These observations challenge the paradigm that mucins are the only molecules that confer biophysical properties of mucus. These observations may ultimately lead to a greater understanding of the system and guide the development of strategies for more effective interventions using better therapeutic agents. PMID:27072609

  6. Rapid detection of Pseudomonas aeruginosa biomarkers in biological fluids using surface-enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Wu, Xiaomeng; Chen, Jing; Zhao, Yiping; Zughaier, Susu M.

    2014-05-01

    Pseudomonas aeruginosa (PA) is an opportunistic pathogen that causes major infection not only in Cystic Fibrosis patients but also in chronic obstructive pulmonary disease and in critically ill patients in intensive care units. Successful antibiotic treatment of the infection relies on accurate and rapid identification of the infectious agents. Conventional microbiological detection methods usually take more than 3 days to obtain accurate results. We have developed a rapid diagnostic technique based on surface-enhanced Raman scattering to directly identify PA from biological fluids. P. aeruginosa strains, PAO1 and PA14, are cultured in lysogeny broth, and the SERS spectra of the broth show the signature Raman peaks from pyocyanin and pyoverdine, two major biomarkers that P. aeruginosa secretes during its growth, as well as lipopolysaccharides. This provides the evidence that the presence of these biomarkers can be used to indicate P. aeruginosa infection. A total of 22 clinical exhaled breath condensates (EBC) samples were obtained from subjects with CF disease and from non-CF healthy donors. SERS spectra of these EBC samples were obtained and further analyzed by both principle component analysis and partial least square-discriminant analysis (PLS-DA). PLS-DA can discriminate the samples with P. aeruginosa infection and the ones without P. aeruginosa infection at 99.3% sensitivity and 99.6% specificity. In addition, this technique can also discriminate samples from subject with CF disease and healthy donor with 97.5% sensitivity and 100% specificity. These results demonstrate the potential of using SERS of EBC samples as a rapid diagnostic tool to detect PA infection.

  7. Pharyngeal airway volume and shape from cone-beam computed tomography: Relationship to facial morphology

    PubMed Central

    Grauer, Dan; Cevidanes, Lucia S. H.; Styner, Martin A.; Ackerman, James L.; Proffit, William R.

    2010-01-01

    Introduction The aim of this study was to assess the differences in airway shape and volume among subjects with various facial patterns. Methods Cone-beam computed tomography records of 62 nongrowing patients were used to evaluate the pharyngeal airway volume (superior and inferior compartments) and shape. This was done by using 3-dimensional virtual surface models to calculate airway volumes instead of estimates based on linear measurements. Subgroups of the sample were determined by anteroposterior jaw relationships and vertical proportions. Results There was a statistically significant relationship between the volume of the inferior component of the airway and the anteroposterior jaw relationship (P = 0.02), and between airway volume and both size of the face and sex (P = 0.02, P = 0.01). No differences in airway volumes related to vertical facial proportions were found. Skeletal Class II patients often had forward inclination of the airway (P <0.001), whereas skeletal Class III patients had a more vertically oriented airway (P = 0.002). Conclusions Airway volume and shape vary among patients with different anteroposterior jaw relationships; airway shape but not volume differs with various vertical jaw relationships. The methods developed in this study make it possible to determine the relationship of 3-dimensional pharyngeal airway surface models to facial morphology, while controlling for variability in facial size. PMID:19962603

  8. Supraglottic airway devices in children

    PubMed Central

    Ramesh, S; Jayanthi, R

    2011-01-01

    Modern anaesthesia practice in children was made possible by the invention of the endotracheal tube (ET), which made lengthy and complex surgical procedures feasible without the disastrous complications of airway obstruction, aspiration of gastric contents or asphyxia. For decades, endotracheal intubation or bag-and-mask ventilation were the mainstays of airway management. In 1983, this changed with the invention of the laryngeal mask airway (LMA), the first supraglottic airway device that blended features of the facemask with those of the ET, providing ease of placement and hands-free maintenance along with a relatively secure airway. The invention and development of the LMA by Dr. Archie Brain has had a significant impact on the practice of anaesthesia, management of the difficult airway and cardiopulmonary resuscitation in children and neonates. This review article will be a brief about the clinical applications of supraglottic airways in children. PMID:22174464

  9. Hydromagnetic Flow and Heat Transfer over a Porous Oscillating Stretching Surface in a Viscoelastic Fluid with Porous Medium.

    PubMed

    Khan, Sami Ullah; Ali, Nasir; Abbas, Zaheer

    2015-01-01

    An analysis is carried out to study the heat transfer in unsteady two-dimensional boundary layer flow of a magnetohydrodynamics (MHD) second grade fluid over a porous oscillating stretching surface embedded in porous medium. The flow is induced due to infinite elastic sheet which is stretched periodically. With the help of dimensionless variables, the governing flow equations are reduced to a system of non-linear partial differential equations. This system has been solved numerically using the finite difference scheme, in which a coordinate transformation is used to transform the semi-infinite physical space to a bounded computational domain. The influence of the involved parameters on the flow, the temperature distribution, the skin-friction coefficient and the local Nusselt number is shown and discussed in detail. The study reveals that an oscillatory sheet embedded in a fluid-saturated porous medium generates oscillatory motion in the fluid. The amplitude and phase of oscillations depends on the rheology of the fluid as well as on the other parameters coming through imposed boundary conditions, inclusion of body force term and permeability of the porous medium. It is found that amplitude of flow velocity increases with increasing viscoelastic and mass suction/injection parameters. However, it decreases with increasing the strength of the applied magnetic field. Moreover, the temperature of fluid is a decreasing function of viscoelastic parameter, mass suction/injection parameter and Prandtl number.

  10. Hydromagnetic Flow and Heat Transfer over a Porous Oscillating Stretching Surface in a Viscoelastic Fluid with Porous Medium

    PubMed Central

    Khan, Sami Ullah; Ali, Nasir; Abbas, Zaheer

    2015-01-01

    An analysis is carried out to study the heat transfer in unsteady two-dimensional boundary layer flow of a magnetohydrodynamics (MHD) second grade fluid over a porous oscillating stretching surface embedded in porous medium. The flow is induced due to infinite elastic sheet which is stretched periodically. With the help of dimensionless variables, the governing flow equations are reduced to a system of non-linear partial differential equations. This system has been solved numerically using the finite difference scheme, in which a coordinate transformation is used to transform the semi-infinite physical space to a bounded computational domain. The influence of the involved parameters on the flow, the temperature distribution, the skin-friction coefficient and the local Nusselt number is shown and discussed in detail. The study reveals that an oscillatory sheet embedded in a fluid-saturated porous medium generates oscillatory motion in the fluid. The amplitude and phase of oscillations depends on the rheology of the fluid as well as on the other parameters coming through imposed boundary conditions, inclusion of body force term and permeability of the porous medium. It is found that amplitude of flow velocity increases with increasing viscoelastic and mass suction/injection parameters. However, it decreases with increasing the strength of the applied magnetic field. Moreover, the temperature of fluid is a decreasing function of viscoelastic parameter, mass suction/injection parameter and Prandtl number. PMID:26657931

  11. Pseudomonas aeruginosa Outer Membrane Vesicles Triggered by Human Mucosal Fluid and Lysozyme Can Prime Host Tissue Surfaces for Bacterial Adhesion

    PubMed Central

    Metruccio, Matteo M. E.; Evans, David J.; Gabriel, Manal M.; Kadurugamuwa, Jagath L.; Fleiszig, Suzanne M. J.

    2016-01-01

    Pseudomonas aeruginosa is a leading cause of human morbidity and mortality that often targets epithelial surfaces. Host immunocompromise, or the presence of indwelling medical devices, including contact lenses, can predispose to infection. While medical devices are known to accumulate bacterial biofilms, it is not well understood why resistant epithelial surfaces become susceptible to P. aeruginosa. Many bacteria, including P. aeruginosa, release outer membrane vesicles (OMVs) in response to stress that can fuse with host cells to alter their function. Here, we tested the hypothesis that mucosal fluid can trigger OMV release to compromise an epithelial barrier. This was tested using tear fluid and corneal epithelial cells in vitro and in vivo. After 1 h both human tear fluid, and the tear component lysozyme, greatly enhanced OMV release from P. aeruginosa strain PAO1 compared to phosphate buffered saline (PBS) controls (∼100-fold). Transmission electron microscopy (TEM) and SDS-PAGE showed tear fluid and lysozyme-induced OMVs were similar in size and protein composition, but differed from biofilm-harvested OMVs, the latter smaller with fewer proteins. Lysozyme-induced OMVs were cytotoxic to human corneal epithelial cells in vitro and murine corneal epithelium in vivo. OMV exposure in vivo enhanced Ly6G/C expression at the corneal surface, suggesting myeloid cell recruitment, and primed the cornea for bacterial adhesion (∼4-fold, P < 0.01). Sonication disrupted OMVs retained cytotoxic activity, but did not promote adhesion, suggesting the latter required OMV-mediated events beyond cell killing. These data suggest that mucosal fluid induced P. aeruginosa OMVs could contribute to loss of epithelial barrier function during medical device-related infections. PMID:27375592

  12. Prevention of allergic airway hyperresponsiveness and remodeling in mice by Astragaliradix Antiasthmatic decoction

    PubMed Central

    2013-01-01

    Background Astragali radix Antiasthmatic Decoction (AAD), a traditional Chinese medication, is found effective in treating allergic diseases and chronic cough. The purpose of this study is to determine whether this medication could suppress allergen-induced airway hyperresponsiveness (AHR) and remodeling in mice, and its possible mechanisms. Methods A mouse model of chronic asthma was used to investigate the effects of AAD on the airway lesions. Mice were sensitized and challenged with ovalbumin (OVA), and the extent of AHR and airway remodeling were characterized. Cells and cytokines in the bronchoalveolar lavage fluid (BALF) were examined. Results AAD treatment effectively decreased OVA-induced AHR, eosinophilic airway inflammation, and collagen deposition around the airway. It significantly reduced the levels of IL-13 and TGF-β1, but exerted inconsiderable effect on INF-γ and IL-10. Conclusions AAD greatly improves the symptoms of allergic airway remodeling probably through inhibition of Th2 cytokines and TGF-β1. PMID:24367979

  13. Measurement of glucose concentration in interstitial fluid by surface plasmon resonance with D-galactose/D-glucose binding protein

    NASA Astrophysics Data System (ADS)

    Li, D. C.; Zhang, J. X.; Wu, P.; Huang, F. X.; Song, B.; Xu, K. X.

    2009-08-01

    A novel minimally invasive way to measure blood glucose concentration is proposed by combining interstitial fluid transdermal extraction and surface plasma resonance (SPR) detecting. 55K Hz low-frequency ultrasound pulse is applied for less than 30 seconds to enhance the skin permeability and then interstitial fluid is extracted out of skin by vacuum. The mathematical model to express the correlation between interstitial fluid glucose and blood glucose is also developed by considering the changes of the skin conductivity. The glucose concentration in the interstitial fluid is determined using an optical SPR biological sensor that measures the refractive index. A protein-glucose binding technology using Dgalactose/ D-glucose Binding Protein for specific absorption of glucose is employed to increase SPR measurement precision. By immobilizing GGBP onto the surface of the SPR sensor, the experimental result indicates the detecting resolution of glucose rises to 1mg/L, the system succeeds in distinguishing glucose from other components in mixture. The feasibility of this method is validated for clinical application with the requirements of bloodless, painless, continuous glucose monitoring and a prototype microfluidic diabetes-monitoring device is under development.

  14. Mucociliary clearance defects in a murine in vitro model of pneumococcal airway infection.

    PubMed

    Fliegauf, Manfred; Sonnen, Andreas F-P; Kremer, Bernhard; Henneke, Philipp

    2013-01-01

    Mucociliary airway clearance is an innate defense mechanism that protects the lung from harmful effects of inhaled pathogens. In order to escape mechanical clearance, airway pathogens including Streptococcus pneumoniae (pneumococcus) are thought to inactivate mucociliary clearance by mechanisms such as slowing of ciliary beating and lytic damage of epithelial cells. Pore-forming toxins like pneumolysin, may be instrumental in these processes. In a murine in vitro airway infection model using tracheal epithelial cells grown in air-liquid interface cultures, we investigated the functional consequences on the ciliated respiratory epithelium when the first contact with pneumococci is established. High-speed video microscopy and live-cell imaging showed that the apical infection with both wildtype and pneumolysin-deficient pneumococci caused insufficient fluid flow along the epithelial surface and loss of efficient clearance, whereas ciliary beat frequency remained within the normal range. Three-dimensional confocal microscopy demonstrated that pneumococci caused specific morphologic aberrations of two key elements in the F-actin cytoskeleton: the junctional F-actin at the apical cortex of the lateral cell borders and the apical F-actin, localized within the planes of the apical cell sides at the ciliary bases. The lesions affected the columnar shape of the polarized respiratory epithelial cells. In addition, the planar architecture of the entire ciliated respiratory epithelium was irregularly distorted. Our observations indicate that the mechanical supports essential for both effective cilia strokes and stability of the epithelial barrier were weakened. We provide a new model, where--in pneumococcal infection--persistent ciliary beating generates turbulent fluid flow at non-planar distorted epithelial surface areas, which enables pneumococci to resist mechanical cilia-mediated clearance.

  15. Airway Microbiota and the Implications of Dysbiosis in Asthma.

    PubMed

    Durack, Juliana; Boushey, Homer A; Lynch, Susan V

    2016-07-01

    The mucosal surfaces of the human body are typically colonized by polymicrobial communities seeded in infancy and are continuously shaped by environmental exposures. These communities interact with the mucosal immune system to maintain homeostasis in health, but perturbations in their composition and function are associated with lower airway diseases, including asthma, a developmental and heterogeneous chronic disease with various degrees and types of airway inflammation. This review will summarize recent studies examining airway microbiota dysbioses associated with asthma and their relationship with the pathophysiology of this disease.

  16. Deep ancient fluids in the continental crust and their impact on near-surface economic, environmental and biological systems.

    NASA Astrophysics Data System (ADS)

    Ballentine, Christopher; Warr, Oliver; Sutcliffe, Chelsea; McDermott, Jill; Fellowes, Jonathan; Holland, Greg; Mabry, Jennifer; Sherwood Lollar, Barbara

    2016-04-01

    With a few exceptions the mobility of water, oil and gas, provides for an ephemeral view of subsurface fluids relative to geological or planetary timescales. Aquifers supplying water for drinking and irrigation have mean residence ages from hundreds to tens of thousands of years; Hydrothermal systems can be active for hundreds of thousands to millions of years forming key mineral reserves; Sedimentary basin formation expels fluids during compaction and generates oil and gas on times scales of millions to hundreds of millions of years. Within these exemplar systems biological activity can play a crucial role by mediating system oxidation state: releasing arsenic into shallow groundwaters; precipitating ore bodies; generating methane; and biodegrading oil. It is becoming increasingly apparent that fluids resident in fractures and porespace in the crystalline basement underlying many of these systems can have a mean residence time that ranges from tens to hundreds of millions of years [1,2] to billions of years [3,4]. These fluids are highly saline and trace element rich; they are abundant in nitrogen, hydrogen, methane and helium and can contain microbes that have uniquely adapted to these isolated environments [5]. We are actively expanding discovery of sites with fluids exhibiting extreme age and have recently shown that these systems contribute to half of the terrestrial hydrogen production; a key component in biosphere energy and carbon cycles [6]. Tectonic or thermal release of these fluids can result in helium deposits; possible ore body generation and the inoculation of near-surface systems with microbial biota protected in the deep surface; the controls and rate of fluid release to shallow systems can fundamentally change the nature of some shallow systems. These deep ancient fluids represent a little tapped scientific resource for understanding how life survives and evolves in such isolation, how life is transported and communicates in extremis together and

  17. Linearized formulation for fluid-structure interaction: Application to the linear dynamic response of a pressurized elastic structure containing a fluid with a free surface

    NASA Astrophysics Data System (ADS)

    Schotté, J.-S.; Ohayon, R.

    2013-05-01

    To control the linear vibrations of structures partially filled with liquids is of prime importance in various industries such as aerospace, naval, civil and nuclear engineering. It is proposed here to investigate a linearized formulation adapted to a rational computation of the vibrations of such coupled systems. Its particularity is to be fully Lagrangian since it considers the fluid displacement field with respect to a static equilibrium configuration as the natural variable describing the fluid motion, as classically done in structural dynamics. As the coupled system considered here is weakly damped in the low frequency domain (low modal density), the analysis of the vibrations of the associated undamped conservative system constitutes the main objective of this paper. One originality of the present formulation is to take into account the effect of the pressurization of the tank on the dynamics of the system, particularly in the case of a compressible liquid. We propose here a new way of deriving the linearized equations of the coupled problem involving a deformable structure and an inner inviscid liquid with a free surface. A review of the classical case considering a heavy incompressible liquid is followed by an application to the new case involving a light compressible liquid. A solution procedure in the frequency domain is proposed and a numerical discretization using the finite element method is discussed. In order to reduce the computational costs, an appropriate reduced order matrix model using modal synthesis approach is also presented.

  18. Harmonic oscillations of a lamina in a viscous fluid near a solid surface: A lattice Boltzmann-immersed boundary approach

    NASA Astrophysics Data System (ADS)

    De Rosis, Alessandro

    2014-12-01

    In this paper, a rigid thickless lamina is immersed in a quiescent viscous fluid and it undergoes transverse finite amplitude harmonic oscillations near a solid surface. The surrounding flow physics is computed through the lattice Boltzmann method. In order to account for the presence of the lamina in the lattice fluid background, the Immersed Boundary method is adopted. Several scenarios are investigated by varying the distance between the initial position of the lamina and the solid wall. For a given lamina-solid surface distance, the effect of the Reynolds number is investigated, together with the influence of the Keulegan-Carpenter number. Findings in terms of drag coefficient show that the force exerted by the encompassing fluid upon the lamina is remarkably influenced by the distance from the solid surface, especially for low values of the Reynolds number. Moreover, such results are confirmed by the computation of the hydrodynamic function. In fact, it highlights that the added mass effect and the non-linear damping experienced by the oscillating lamina grow as the above mentioned distance and the Reynolds number reduce.

  19. Electrolyte transport properties in distal small airways from cystic fibrosis pigs with implications for host defense

    PubMed Central

    Tang, Xiao Xiao; Vargas Buonfiglio, Luis G.; Comellas, Alejandro P.; Thornell, Ian M.; Ramachandran, Shyam; Karp, Philip H.; Taft, Peter J.; Sheets, Kelsey; Abou Alaiwa, Mahmoud H.; Welsh, Michael J.; Stoltz, David A.; Zabner, Joseph

    2016-01-01

    While pathological and clinical data suggest that small airways are involved in early cystic fibrosis (CF) lung disease development, little is known about how the lack of cystic fibrosis transmembrane conductance regulator (CFTR) function contributes to disease pathogenesis in these small airways. Large and small airway epithelia are exposed to different airflow velocities, temperatures, humidity, and CO2 concentrations. The cellular composition of these two regions is different, and small airways lack submucosal glands. To better understand the ion transport properties and impacts of lack of CFTR function on host defense function in small airways, we adapted a novel protocol to isolate small airway epithelial cells from CF and non-CF pigs and established an organotypic culture model. Compared with non-CF large airways, non-CF small airway epithelia cultures had higher Cl− and bicarbonate (HCO3−) short-circuit currents and higher airway surface liquid (ASL) pH under 5% CO2 conditions. CF small airway epithelia were characterized by minimal Cl− and HCO3− transport and decreased ASL pH, and had impaired bacterial killing compared with non-CF small airways. In addition, CF small airway epithelia had a higher ASL viscosity than non-CF small airways. Thus, the activity of CFTR is higher in the small airways, where it plays a role in alkalinization of ASL, enhancement of antimicrobial activity, and lowering of mucus viscosity. These data provide insight to explain why the small airways are a susceptible site for the bacterial colonization. PMID:26801568

  20. Osmotic regulation of airway reactivity by epithelium.

    PubMed

    Fedan, J S; Yuan, L X; Chang, V C; Viola, J O; Cutler, D; Pettit, L L

    1999-05-01

    Inhalation of nonisotonic solutions can elicit pulmonary obstruction in asthmatic airways. We evaluated the hypothesis that the respiratory epithelium is involved in responses of the airways to nonisotonic solutions using the guinea pig isolated, perfused trachea preparation to restrict applied agents to the mucosal (intraluminal) or serosal (extraluminal) surface of the airway. In methacholine-contracted tracheae, intraluminally applied NaCl or KCl equipotently caused relaxation that was unaffected by the cyclo-oxygenase inhibitor, indomethacin, but was attenuated by removal of the epithelium and Na+ and Cl- channel blockers. Na+-K+-2Cl- cotransporter and nitric oxide synthase blockers caused a slight inhibition of relaxation, whereas Na+,K+-pump inhibition produced a small potentiation. Intraluminal hyperosmolar KCl and NaCl inhibited contractions in response to intra- or extraluminally applied methacholine, as well as neurogenic cholinergic contractions elicited with electric field stimulation (+/- indomethacin). Extraluminally applied NaCl and KCl elicited epithelium-dependent relaxation (which for KCl was followed by contraction). In contrast to the effects of hyperosmolarity, intraluminal hypo-osmolarity caused papaverine-inhibitable contractions (+/- epithelium). These findings suggest that the epithelium is an osmotic sensor which, through the release of epithelium-derived relaxing factor, can regulate airway diameter by modulating smooth muscle responsiveness and excitatory neurotransmission.

  1. Simulation of Two-Fluid Flows by the Least-Squares Finite Element Method Using a Continuum Surface Tension Model

    NASA Technical Reports Server (NTRS)

    Wu, Jie; Yu, Sheng-Tao; Jiang, Bo-nan

    1996-01-01

    In this paper a numerical procedure for simulating two-fluid flows is presented. This procedure is based on the Volume of Fluid (VOF) method proposed by Hirt and Nichols and the continuum surface force (CSF) model developed by Brackbill, et al. In the VOF method fluids of different properties are identified through the use of a continuous field variable (color function). The color function assigns a unique constant (color) to each fluid. The interfaces between different fluids are distinct due to sharp gradients of the color function. The evolution of the interfaces is captured by solving the convective equation of the color function. The CSF model is used as a means to treat surface tension effect at the interfaces. Here a modified version of the CSF model, proposed by Jacqmin, is used to calculate the tension force. In the modified version, the force term is obtained by calculating the divergence of a stress tensor defined by the gradient of the color function. In its analytical form, this stress formulation is equivalent to the original CSF model. Numerically, however, the use of the stress formulation has some advantages over the original CSF model, as it bypasses the difficulty in approximating the curvatures of the interfaces. The least-squares finite element method (LSFEM) is used to discretize the governing equation systems. The LSFEM has proven to be effective in solving incompressible Navier-Stokes equations and pure convection equations, making it an ideal candidate for the present applications. The LSFEM handles all the equations in a unified manner without any additional special treatment such as upwinding or artificial dissipation. Various bench mark tests have been carried out for both two dimensional planar and axisymmetric flows, including a dam breaking, oscillating and stationary bubbles and a conical liquid sheet in a pressure swirl atomizer.

  2. Ionic fluids in lubrication of aluminium-steel contacts. Surface and tribochemical interactions

    NASA Astrophysics Data System (ADS)

    Jimenez Ballesta, Ana Eva

    Room-temperature ionic liquids (ILs) are high performance fluids with a wide thermal stability range. They are being studied as new lubricants in a variety of sliding contacts. One of their more interesting tribological applications is that of steel-aluminium lubrication. In this work we study the influence of the lateral alkyl chain length and of the anion on the lubricating ability of six imidazolium ILs, a pyridinium and a phosphonium derivative. For first time, these ILs have been studied as neat lubricants and as 1wt.% base oil additives in variable conditions of velocity, load and temperature in pin-on-disk tests for AISI 52100 steel-ASTM 2011 aluminium contacts. In this work we present the first study of ILs as lubricants under extreme temperature conditions. The tribological performance of ILs has been compared with that of a mineral oil and of a synthetic ester. Under these conditions, ILs show lower friction and wear values than conventional oils at all temperatures. As 1wt.% additives, the conditions of optimum lubrication and the transitions between regimes and lubrication mechanisms have been determined. We have also studied the performance of ILs as 1wt.% additives of the synthetic oil. A relationship between additive polarity and wear index has been established. If the more soluble phosphonium IL additive is used, no friction or wear reduction takes place due to competition between solvation and adsorption processes. Electronic microscopy (SEM), energy dispersive (EDS) and X-ray photoelectron (XPS) spectroscopies have been used to study the wear mechanisms and tribochemical processes that take place in the contact. Finally, we have studied the performance of three aluminium alloys in corrosion and erosion-corrosion tests. In immersion tests with free-water ILs, the aluminium alloy 2011 shows a good resistance to corrosion, but dilution of 1-ethyl, 3-methylimidazolium tetrafluoroborate in water produces the hydrolysis of the anion and the corrosion of

  3. Liquid microjunction surface sampling probe fluid dynamics: computational and experimental analysis of coaxial intercapillary positioning effects on sample manipulation.

    PubMed

    Elnaggar, Mariam S; Barbier, Charlotte; Van Berkel, Gary J

    2011-07-01

    A coaxial geometry liquid microjunction surface sampling probe (LMJ-SSP) enables direct extraction of analytes from surfaces for subsequent analysis by techniques like mass spectrometry. Solution dynamics at the probe-to-sample surface interface in the LMJ-SSP has been suspected to influence sampling efficiency and dispersion but has not been rigorously investigated. The effect on flow dynamics and analyte transport to the mass spectrometer caused by coaxial retraction of the inner and outer capillaries from each other and the surface during sampling with a LMJ-SSP was investigated using computational fluid dynamics and experimentation. A transparent LMJ-SSP was constructed to provide the means for visual observation of the dynamics of the surface sampling process. Visual observation, computational fluid dynamics (CFD) analysis, and experimental results revealed that inner capillary axial retraction from the flush position relative to the outer capillary transitioned the probe from a continuous sampling and injection mode through an intermediate regime to sample plug formation mode caused by eddy currents at the sampling end of the probe. The potential for analytical implementation of these newly discovered probe operational modes is discussed.

  4. Liquid Microjunction Surface Sampling Probe Fluid Dynamics: Computational and Experimental Analysis of Coaxial Intercapillary Positioning Effects on Sample Manipulation

    NASA Astrophysics Data System (ADS)

    ElNaggar, Mariam S.; Barbier, Charlotte; Van Berkel, Gary J.

    2011-07-01

    A coaxial geometry liquid microjunction surface sampling probe (LMJ-SSP) enables direct extraction of analytes from surfaces for subsequent analysis by techniques like mass spectrometry. Solution dynamics at the probe-to-sample surface interface in the LMJ-SSP has been suspected to influence sampling efficiency and dispersion but has not been rigorously investigated. The effect on flow dynamics and analyte transport to the mass spectrometer caused by coaxial retraction of the inner and outer capillaries from each other and the surface during sampling with a LMJ-SSP was investigated using computational fluid dynamics and experimentation. A transparent LMJ-SSP was constructed to provide the means for visual observation of the dynamics of the surface sampling process. Visual observation, computational fluid dynamics (CFD) analysis, and experimental results revealed that inner capillary axial retraction from the flush position relative to the outer capillary transitioned the probe from a continuous sampling and injection mode through an intermediate regime to sample plug formation mode caused by eddy currents at the sampling end of the probe. The potential for analytical implementation of these newly discovered probe operational modes is discussed.

  5. Analysis of surface segregation in polymer mixtures: A combination of mean field and statistical associated fluid theories

    NASA Astrophysics Data System (ADS)

    Krawczyk, Jaroslaw; Croce, Salvatore; Chakrabarti, Buddhapriya; Tasche, Jos

    The surface segregation in polymer mixtures remains a challenging problem for both academic exploration as well as industrial applications. Despite its ubiquity and several theoretical attempts a good agreement between computed and experimentally observed profiles has not yet been achieved. A simple theoretical model proposed in this context by Schmidt and Binder combines Flory-Huggins free energy of mixing with the square gradient theory of wetting of a wall by fluid. While the theory gives us a qualitative understanding of the surface induced segregation and the surface enrichment it lacks the quantitative comparison with the experiment. The statistical associating fluid theory (SAFT) allows us to calculate accurate free energy for a real polymeric materials. In an earlier work we had shown that increasing the bulk modulus of a polymer matrix through which small molecules migrate to the free surface causes reduction in the surface migrant fraction using Schmidt-Binder and self-consistent field theories. In this work we validate this idea by combining mean field theories and SAFT to identify parameter ranges where such an effect should be observable. Department of Molecular Physics, Łódź University of Technology, Żeromskiego 116, 90-924 Łódź, Poland.

  6. Airway cooling and mucosal injury during cold weather exercise.

    PubMed

    Davis, M S; Lockard, A J; Marlin, D J; Freed, A N

    2002-09-01

    In human subjects that exercise strenuously in cold weather, there is evidence that hyperventilation with cold air leads to peripheral airway cooling, desiccation and mucosal injury. Our hypothesis was that hyperventilation with cold air can result in penetration of unconditioned air (air that is not completely warmed and humidified) into the peripheral airways of exercising horses, resulting in peripheral airway mucosal injury. To test this hypothesis, a thermister-tipped catheter was inserted through the midcervical trachea and advanced into a sublobar bronchus in three horses that cantered on a treadmill at 6.6 m/s while breathing cold (5 degrees C) air. The mean (+/- s.e.) intra-airway temperature during cantering was 33.3 +/- 0.4 degrees C, a value comparable to the bronchial lumen temperatures measured in man during maximal exercise while breathing subfreezing dry air. In a second experiment, 6 fit Thoroughbred racehorses with satisfactory performance were used to determine whether strenuous exercise in cold conditions can produce airway injury. Horses were assigned to Exercise (E) or Control (C) groups in a random crossover design. Samples of bronchoalveolar lavage fluid (BALF) in the E treatment were recovered within 30 min of galloping exercise in 4 degrees C, 100% relative humidity (E), while in C BALF samples were obtained when the horses had not performed any exercise for at least 48 h prior. Ciliated epithelial cells in BALF were higher in E than in the C treatment. Similar results have been found in human athletes and laboratory animal models of cold weather exercise. These results support the hypothesis that, similar to man, horses that exercise in cold weather experience peripheral airway mucosal injury due to the penetration of unconditioned air. Furthermore, these results suggest that airway cooling and desiccation may be a factor in airway inflammation commonly found in equine athletes.

  7. Modeling the Nonlinear Motion of the Rat Central Airways.

    PubMed

    Ibrahim, G; Rona, A; Hainsworth, S V

    2016-01-01

    Advances in volumetric medical imaging techniques allowed the subject-specific modeling of the bronchial flow through the first few generations of the central airways using computational fluid dynamics (CFD). However, a reliable CFD prediction of the bronchial flow requires modeling of the inhomogeneous deformation of the central airways during breathing. This paper addresses this issue by introducing two models of the central airways motion. The first model utilizes a node-to-node mapping between the discretized geometries of the central airways generated from a number of successive computed tomography (CT) images acquired dynamically (without breath hold) over the breathing cycle of two Sprague-Dawley rats. The second model uses a node-to-node mapping between only two discretized airway geometries generated from the CT images acquired at end-exhale and at end-inhale along with the ventilator measurement of the lung volume change. The advantage of this second model is that it uses just one pair of CT images, which more readily complies with the radiation dosage restrictions for humans. Three-dimensional computer aided design geometries of the central airways generated from the dynamic-CT images were used as benchmarks to validate the output from the two models at sampled time-points over the breathing cycle. The central airway geometries deformed by the first model showed good agreement to the benchmark geometries within a tolerance of 4%. The central airway geometry deformed by the second model better approximated the benchmark geometries than previous approaches that used a linear or harmonic motion model.

  8. Patterns of recruitment and injury in a heterogeneous airway network model

    PubMed Central

    Stewart, Peter S.; Jensen, Oliver E.

    2015-01-01

    In respiratory distress, lung airways become flooded with liquid and may collapse due to surface-tension forces acting on air–liquid interfaces, inhibiting gas exchange. This paper proposes a mathematical multiscale model for the mechanical ventilation of a network of occluded airways, where air is forced into the network at a fixed tidal volume, allowing investigation of optimal recruitment strategies. The temporal response is derived from mechanistic models of individual airway reopening, incorporating feedback on the airway pressure due to recruitment. The model accounts for stochastic variability in airway diameter and stiffness across and between generations. For weak heterogeneity, the network is completely ventilated via one or more avalanches of recruitment (with airways recruited in quick succession), each characterized by a transient decrease in the airway pressure; avalanches become more erratic for airways that are initially more flooded. However, the time taken for complete ventilation of the network increases significantly as the network becomes more heterogeneous, leading to increased stresses on airway walls. The model predicts that the most peripheral airways are most at risk of ventilation-induced damage. A positive-end-expiratory pressure reduces the total recruitment time but at the cost of larger stresses exerted on airway walls. PMID:26423440

  9. The coupling of surface charge and boundary slip at the solid-liquid interface and their combined effect on fluid drag: A review.

    PubMed

    Jing, Dalei; Bhushan, Bharat

    2015-09-15

    Fluid drag of micro/nano fluidic systems has inspired wide scientific interest. Surface charge and boundary slip at the solid-liquid interface are believed to affect fluid drag. This review summarizes the recent studies on the coupling of surface charge and slip, and their combined effect on fluid drag at micro/nano scale. The effect of pH on surface charge of borosilicate glass and silica surfaces in deionized (DI) water and saline solution is discussed using a method based on colloidal probe atomic force microscopy (AFM). The boundary slip of various oil-solid interfaces are discussed for samples with different degrees of oleophobicity prepared by nanoparticle-binder system. By changing the pH of solution or applying an electric field, effect of surface charge on slip of a smooth hydrophobic octadecyltrichlorosilane (OTS) in DI water and saline solution is studied. A theoretical model incorporating the coupling relationship between surface charge and slip is used to discuss the combined effect of surface charge-induced electric double layer (EDL) and slip on fluid drag of pressure-driven flow in a one-dimensional parallel-plates microchannel. A theoretical method is used to reduce the fluid drag. The studies show that the increasing magnitude of surface charge density leads to a decrease in slip length. The surface charge results in a larger fluid drag, and the coupling of surface charge and slip can further increase the fluid drag. Surface charge-induced EDLs with asymmetric zeta potentials can effectively reduce the fluid drag.

  10. Extensional flow of low-viscosity fluids in capillary bridges formed by pulsed surface acoustic wave jetting

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, P. K.; McDonnell, A. G.; Prabhakar, R.; Yeo, L. Y.; Friend, J.

    2011-02-01

    Forming capillary bridges of low-viscosity (lsim10 mPa s) fluids is difficult, making the study of their capillary-thinning behavior and the measurement of the fluid's extensional viscosity difficult as well. Current techniques require some time to form a liquid bridge from the stretching of a droplet. Rapidly stretching a liquid bridge using these methods can cause its breakup if the viscosity is too low. Stretching more slowly allows the bridge to thin and break up before a suitable bridge geometry can be established to provide reliable and accurate rheological data. Using a pulsed surface acoustic wave to eject a jet from a sessile droplet, a capillary bridge may be formed in about 7.5 ms, about seven times quicker than current methods. With this approach, capillary bridges may be formed from Newtonian and non-Newtonian fluids having much lower viscosities—water, 0.04% by weight solution of high-molecular-weight (7 MDa) polystyrene in dioctyl phthalate and 0.25% fibrinogen solution in demineralized water, for example. Details of the relatively simple system used to achieve these results are provided, as are experimental results indicating deviations from a Newtonian response by the low-viscosity non-Newtonian fluids used in our study.

  11. Hydrothermal fluid flow models of Campi Flegrei caldera, Italy constrained by InSAR surface deformation time series observations

    NASA Astrophysics Data System (ADS)

    Lundgren, P.; Lanari, R.; Manzo, M.; Sansosti, E.; Tizzani, P.; Hutnak, M.; Hurwitz, S.

    2008-12-01

    Campi Flegrei caldera, Italy, located along the Bay of Naples, has a long history of significant vertical deformation, with the most recent large uplift (>1.5m) occurring in 1983-1984. Each episode of uplift has been followed by a period of subsidence that decreases in rate with time and may be punctuated by brief episodes of lesser uplift. The large amplitude of the major uplifts that occur without volcanic activity, and the subsequent subsidence has been argued as evidence for hydrothermal amplification of any magmatic source. The later subsidence and its temporal decay have been argued as due to diffusion of the pressurized caldera fill material into the less porous surrounding country rock. We present satellite synthetic aperture radar (SAR) interferometry (InSAR) time series analysis of ERS and Envisat data from the European Space Agency, based on exploiting the Small Baseline Subset (SBAS) approach [Berardino et al., 2002]; this allows us to generate maps of relative surface deformation though time, beginning in 1992 through 2007, that are relevant to both ascending and descending satellite orbits. The general temporal behavior is one of subsidence punctuated by several lesser uplift episodes. The spatial pattern of deformation can be modeled through simple inflation/deflation sources in an elastic halfspace. Given the evidence to suggest that fluids may play a significant role in the temporal deformation of Campi Flegrei, rather than a purely magmatic or magma chamber-based interpretation, we model the temporal and spatial evolution of surface deformation as a hydrothermal fluid flow process. We use the TOUGH2-BIOT2 set of numerical codes [Preuss et al., 1999; Hsieh, 1996], which couple multi-phase (liquid-gas) and multi-component (H2O-CO2) fluid flow in a porous or fractured media with plane strain deformation and fluid flow in a linearly elastic porous medium. We explore parameters related to the depth and temporal history of fluid injection, fluid

  12. Plane surface suddenly set in motion in a viscoelastic fluid with fractional Maxwell model

    NASA Astrophysics Data System (ADS)

    Wenchang, Tan; Mingyu, Xu

    2002-08-01

    The fractional calculus approach in the constitutive relationship model of viscoelastic fluid is introduced. The flow near a wall suddenly set in motion is studied for a non-Newtonian viscoelastic fluid with the fractional Maxwell model. Exact solutions of velocity and stress are obtained by using the discrete inverse Laplace transform of the sequential fractional derivatives. It is found that the effect of the fractional orders in the constitutive relationship on the flow field is significant. The results show that for small times there are appreciable viscoelastic effects on the shear stress at the plate, for large times the viscoelastic effects become weak.

  13. Mature cystic fibrosis airway neutrophils suppress T cell function: evidence for a role of arginase 1 but not programmed death-ligand 1.

    PubMed

    Ingersoll, Sarah A; Laval, Julie; Forrest, Osric A; Preininger, Marcela; Brown, Milton R; Arafat, Dalia; Gibson, Greg; Tangpricha, Vin; Tirouvanziam, Rabindra

    2015-06-01

    Bacteria colonize cystic fibrosis (CF) airways, and although T cells with appropriate Ag specificity are present in draining lymph nodes, they are conspicuously absent from the lumen. To account for this absence, we hypothesized that polymorphonuclear neutrophils (PMNs), recruited massively into the CF airway lumen and actively exocytosing primary granules, also suppress T cell function therein. Programmed death-ligand 1 (PD-L1), which exerts T cell suppression at a late step, was expressed bimodally on CF airway PMNs, delineating PD-L1(hi) and PD-L1(lo) subsets, whereas healthy control (HC) airway PMNs were uniformly PD-L1(hi). Blood PMNs incubated in CF airway fluid lost PD-L1 over time; in coculture, Ab blockade of PD-L1 failed to inhibit the suppression of T cell proliferation by CF airway PMNs. In contrast with PD-L1, arginase 1 (Arg1), which exerts T cell suppression at an early step, was uniformly high on CF and HC airway PMNs. However, arginase activity was high in CF airway fluid and minimal in HC airway fluid, consistent with the fact that Arg1 activation requires primary granule exocytosis, which occurs in CF, but not HC, airway PMNs. In addition, Arg1 expression on CF airway PMNs correlated negatively with lung function and positively with arginase activity in CF airway fluid. Finally, combined treatment with arginase inhibitor and arginine rescued the suppression of T cell proliferation by CF airway fluid. Thus, Arg1 and PD-L1 are dynamically modulated upon PMN migration into human airways, and, Arg1, but not PD-L1, contributes to early PMN-driven T cell suppression in CF, likely hampering resolution of infection and inflammation.

  14. MATURE CYSTIC FIBROSIS AIRWAY NEUTROPHILS SUPPRESS T-CELL FUNCTION: EVIDENCE FOR A ROLE OF ARGINASE 1, BUT NOT PROGRAMMED DEATH-LIGAND 1

    PubMed Central

    Ingersoll, Sarah A.; Laval, Julie; Forrest, Osric A.; Preininger, Marcela; Brown, Milton R.; Arafat, Dalia; Gibson, Greg; Tangpricha, Vin; Tirouvanziam, Rabindra

    2015-01-01

    Bacteria colonize cystic fibrosis (CF) airways, and while T cells with appropriate antigen specificity are present in draining lymph nodes, they are conspicuously absent from the lumen. To account for this absence, we hypothesized that polymorphonuclear neutrophils (PMNs), recruited massively into the CF airway lumen and actively exocytosing primary granules, also suppress T-cell function therein. Programmed Death-Ligand 1 (PD-L1), which exerts T-cell suppression at a late step, was expressed bimodally on CF airway PMNs, delineating PD-L1hi and PD-L1lo subsets, while healthy control (HC) airway PMNs were uniformly PD-L1hi. Blood PMNs incubated in CF airway fluid lost PD-L1 over time, and in coculture, antibody blockade of PD-L1 failed to inhibit the suppression of T-cell proliferation by CF airway PMNs. In contrast with PD-L1, arginase 1 (Arg1), which exerts T-cell suppression at an early step, was uniformly high on CF and HC airway PMNs. However, arginase activity was high in CF airway fluid and minimal in HC airway fluid, consistent with the fact that Arg1 activation requires primary granule exocytosis, which occurs in CF, but not HC, airway PMNs. In addition, Arg1 expression on CF airway PMNs correlated negatively with lung function and positively with arginase activity in CF airway fluid. Finally, combined treatment with arginase inhibitor and arginine rescued the suppression of T-cell proliferation by CF airway fluid. Thus, Arg1 and PD-L1 are dynamically modulated upon PMN migration into human airways, and, Arg1, but not PD-L1, contributes to early PMN-driven T-cell suppression in CF, likely hampering resolution of infection and inflammation. PMID:25926674

  15. Surface Modification Methods to Control Wettability in Immiscible Fluid Displacement Experimental Model Systems Relevant to Geological Carbon Sequestration

    NASA Astrophysics Data System (ADS)

    Grate, J. W.; Warner, M. G.; Oostrom, M.; Zhang, C.; Wietsma, T. W.; Pittman, J. W.; Dehoff, K. J.

    2011-12-01

    Wettability is a critical parameter influencing immiscible fluid displacements relevant to geological carbon sequestration. Fully water-wet clean silica surfaces can be modified with silanes to alter the wettability, with the majority of such efforts to date related to conversions of water-wet to oil-wet systems. While a sizable literature exist on contact angles obtained on silanized surfaces, these are by and large air-water contact angle data, not the oil-water contact angles needed. We have investigated a large range of silanes to modify silica surfaces over a range of wettabilities, measuring both air-water and oil-water contact angles. We have identified surface modifications to produce intermediate wet surfaces. We have found a linear correlation between air-water contact angles and oil-water contact angles, enabling literature data on air-water contact angles to be interpreted in terms of likely oil-water contact angles. In addition, we have found that while glass and silica surfaces modified by the same chemistry give the same contact angles in terms of air water contact angles, the surfaces are not as similar in terms of oil-water contact angles. These studies are being carried out in conjunction with immiscible displacements of water by liquid and supercritical CO2 in microfabricated pore network micromodels in silicon with oxidized silica surfaces and glass cover plates.

  16. CD38 and airway hyper-responsiveness: studies on human airway smooth muscle cells and mouse models.

    PubMed

    Guedes, Alonso G P; Deshpande, Deepak A; Dileepan, Mythili; Walseth, Timothy F; Panettieri, Reynold A; Subramanian, Subbaya; Kannan, Mathur S

    2015-02-01

    Asthma is an inflammatory disease in which altered calcium regulation, contractility, and airway smooth muscle (ASM) proliferation contribute to airway hyper-responsiveness and airway wall remodeling. The enzymatic activity of CD38, a cell-surface protein expressed in human ASM cells, generates calcium mobilizing second messenger molecules such as cyclic ADP-ribose. CD38 expression in human ASM cells is augmented by cytokines (e.g., TNF-α) that requires the activation of MAP kinases and the transcription factors, NF-κB and AP-1, and is post-transcriptionally regulated by miR-140-3p and miR-708 by binding to 3' Untranslated Region of CD38 as well as by modulating the activation of signaling mechanisms involved in its regulation. Mice deficient in Cd38 exhibit reduced airway responsiveness to inhaled methacholine relative to the response in wild-type mice. Intranasal challenge of Cd38-deficient mice with TNF-α or IL-13, or the environmental fungus Alternaria alternata, causes significantly attenuated methacholine responsiveness compared with wild-type mice, with comparable airway inflammation. Reciprocal bone marrow transfer studies revealed partial restoration of airway hyper-responsiveness to inhaled methacholine in the Cd38-deficient mice. These studies provide evidence for CD38 involvement in the development of airway hyper-responsiveness; a hallmark feature of asthma. Future studies aimed at drug discovery and delivery targeting CD38 expression and (or) activity are warranted.

  17. Free-Surface Computational Fluid Dynamics Modeling of a Spillway and Tailrace: Case Study of The Dalles Project

    SciTech Connect

    Cook, Chris B.; Richmond, Marshall C.; Serkowski, John A.; Ebner, Laurie L.

    2002-07-30

    Based upon acoustic tracking and fish tagging data, The Dalles Project constructed and operated by the U. S. Army Corps of Engineers has been shown to have the highest mortality rates for juvenile salmonids on the Lower Columbia River. In efforts to assist the hydraulic and biological communities in managing this hydroelectric project, a three-dimensional computational fluid dynamics (CFD) model was applied to the spillway, stilling basin, and tailrace zones downstream of the dam. To simulate the highly transient and turbulent flow conditions in this region, a free-surface computational fluid dynamics (CFD) numerical model has been applied. This model is based upon the volume-of-fluids (VOF) method, and is capable of simulating sudden discontinuities in the free surface, including wave breakup. The model solves the non-hydrostatic Reynolds-averaged Navier-Stokes (RANS) equations over variable-sized hexahedral cells. To verify the ability of the numerical model to simulate flows downstream of the spillway, the model was verified against data from three different physical models of The Dalles tailrace at scales of 1:36, 1:40, and 1:80. Results from these physical models allow for validation of the numerical model at various scales of motion from the small scale highly dynamic variations near the baffle blocks (1:36 and 1:40 scale) to the larger scale general circulation patterns that encompass the tailrace (1:80 scale).

  18. Determination of surface tension and contact angle from the shapes of axisymmetric fluid interfaces without use of apex coordinates.

    PubMed

    Cabezas, M Guadalupe; Bateni, Arash; Montanero, José M; Neumann, A Wilhelm

    2006-11-21

    Drop shape techniques, such as axisymmetric drop shape analysis, are widely used to measure surface properties, as they are accurate and reliable. Nevertheless, they are not applicable in experimental studies dealing with fluid configurations that do not present an apex. A new methodology is presented for measuring interfacial properties of liquids, such as surface tension and contact angles, by analyzing the shape of an axisymmetric liquid-fluid interface without use of apex coordinates. The theoretical shape of the interface is generated numerically as a function of surface tension and some geometrical parameters at the starting point of the interface, e.g., contact angle and radius of the interface. Then, the numerical shape is fitted to the experimental profile, taking the interfacial properties as adjustable parameters. The best fit identifies the true values of surface tension and contact angle. Comparison between the experimental and the theoretical profiles is performed using the theoretical image fitting analysis (TIFA) strategy. The new method, TIFA-axisymmetric interfaces (TIFA-AI), is applicable to any axisymmetric experimental configuration (with or without apex). The versatility and accuracy of TIFA-AI is shown by considering various configurations: liquid bridges, sessile and pendant drops, and liquid lenses.

  19. Continuum-kinetic-microscopic model of lung clearance due to core-annular fluid entrainment

    NASA Astrophysics Data System (ADS)

    Mitran, Sorin

    2013-07-01

    The human lung is protected against aspirated infectious and toxic agents by a thin liquid layer lining the interior of the airways. This airway surface liquid is a bilayer composed of a viscoelastic mucus layer supported by a fluid film known as the periciliary liquid. The viscoelastic behavior of the mucus layer is principally due to long-chain polymers known as mucins. The airway surface liquid is cleared from the lung by ciliary transport, surface tension gradients, and airflow shear forces. This work presents a multiscale model of the effect of airflow shear forces, as exerted by tidal breathing and cough, upon clearance. The composition of the mucus layer is complex and variable in time. To avoid the restrictions imposed by adopting a viscoelastic flow model of limited validity, a multiscale computational model is introduced in which the continuum-level properties of the airway surface liquid are determined by microscopic simulation of long-chain polymers. A bridge between microscopic and continuum levels is constructed through a kinetic-level probability density function describing polymer chain configurations. The overall multiscale framework is especially suited to biological problems due to the flexibility afforded in specifying microscopic constituents, and examining the effects of various constituents upon overall mucus transport at the continuum scale.

  20. Onset of motion at the surface of a porous granular bed by a shearing fluid flow

    NASA Astrophysics Data System (ADS)

    Hong, Anyu; Tao, Mingjiang; Kudrolli, Arshad

    2014-03-01

    We will discuss an experimental investigation of the onset of particle motion by a fluid flow over an unconsolidated granular bed. This situation arises in a number of natural and industrial processes including wind blowing over sand, sediment transport in rivers, tidal flows interacting with beaches and flows in slurry pipelines and mixing tanks. The Shields criteria given by the ratio of the viscous shear and normal stresses is used to understand the onset of motion. However, reviews reveals considerable scatter while noting broad trends with Reynolds Number. We discuss an idealized model system where fluid flows with a prescribed flow rate through a horizontal rectangular pipe initially fully filled with granular beads. The granular bed height decreases and reaches a constant height when the shear stress at the boundary decreases below a critical value. We compare and contrast the values obtained assuming no-slip boundary conditions with those observed with PIV using florescent tracer particles to measure the actual fluid flow profile near the porous interface. We will also report the observed variation of the Shields criteria with particle Reynolds Number by varying particle size and fluid flow rates.

  1. Surface Roughness Effects on Fluid Transport Through a Natural Rock Fracture

    SciTech Connect

    Crandall, D.M.; Ahmadi, Goodarz; Smith, D.H.

    2008-04-01

    Fluid flow through rock fractures can be orders of magnitude faster than through the adjacent low-permeability rock. Understanding how fluid moves through these pathways is important for the prediction of sequestered CO2 transport in geologic reservoirs. Reservoir-scale, discrete-fracture simulators use simplified models of flow through fractures to determine transport properties in complex fracture networks. A high level of approximation is required in these reservoir-scale simulations due to the number of fractures within the domain of interest and because of the limited amount of information that can be obtained from geophysical well-logs (Long et al. (1996)). For this study, flow simulations through a CT-scanned fracture were performed to evaluate different fluid transport parameters that are important in geological flow analysis. The ‘roughness’ of the fracture was varied to determine the effect of the bumpy fracture walls on the fluid flow. The permeability and effective aperture were determined for flow under a constant pressure head. The fracture roughness is shown to dramatically reduce the flow through the fracture, and various relations are described.

  2. Virial series for inhomogeneous fluids applied to the Lennard-Jones wall-fluid surface tension at planar and curved walls.

    PubMed

    Urrutia, Ignacio; Paganini, Iván E

    2016-05-07

    We formulate a straightforward scheme of statistical mechanics for inhomogeneous systems that includes the virial series in powers of the activity for the grand free energy and density distributions. There, cluster integrals formulated for inhomogeneous systems play a main role. We center on second order terms that were analyzed in the case of hard-wall confinement, focusing in planar, spherical, and cylindrical walls. Further analysis was devoted to the Lennard-Jones system and its generalization, the 2k-k potential. For these interaction potentials, the second cluster integral was evaluated analytically. We obtained the fluid-substrate surface tension at second order for the planar, spherical, and cylindrical confinement. Spherical and cylindrical cases were analyzed using a series expansion in the radius including higher order terms. We detected a lnR/R(2) dependence of the surface tension for the standard Lennard-Jones system confined by spherical and cylindrical walls, no matter if particles are inside or outside of the hard walls. The analysis was extended to bending and Gaussian curvatures, where exact expressions were also obtained.

  3. Upper airway segmentation and measurement in MRI using fuzzy connectedness

    NASA Astrophysics Data System (ADS)

    Liu, Jianguo; Udupa, Jayaram K.; Odhner, Dewey; McDonough, Joe M.; Arens, Raanan

    2002-04-01

    The purpose of this work is to build a computerized system for the delineation of upper airway structures via MRI and to evaluate its effectiveness for routine clinical use in aiding diagnosis of upper airway disorders in children. We use two MRI protocols, axial T1 and T2, to gather information about different aspects of the airway and its surrounding soft tissue structures including adenoid, tonsils, tongue and soft palate. These images are processed and segmented to compute the architectural parameters of the airway such as its surface description, volume, central (medial) line, and cross-sectional areas at planes orthogonal to the central line. We have built a software package based on 3DVIEWNIX and running on a 450 MHz Pentium PC under Linux system (and on a Sun workstation under Unix) for the various operations of visualization, segmentation, registration, prefiltering, interpolation, standardization, and quantitative analysis of the airway. The system has been tested utilizing 40 patient studies. For every study, the system segmented and displayed a smooth 3D rendition of the airway, its central line and a plot of the cross-sectional area of the airway orthogonal to the central line as a function of the distance from one end of the central line. The tests indicate 97% precision and accuracy for segmentation. The mean time taken per study is about 4 minutes for the airway. This includes operator interaction time and processing time. This method provides a robust and fast means of assessing the airway size, shape, and places of restriction, as well as providing a structural data set suitable for use in modeling studies of airflow and mechanics.

  4. Immunomodulatory Effects of Ambroxol on Airway Hyperresponsiveness and Inflammation

    PubMed Central

    Miyahara, Nobuaki; Matsubara, Shigeki; Taube, Christian; Kitamura, Kenichi; Hirano, Astushi; Tanimoto, Mitsune; Gelfand, Erwin W.

    2016-01-01

    Ambroxol is used in COPD and asthma to increase mucociliary clearance and regulate surfactant levels, perhaps through anti-oxidant and anti-inflammatory activities. To determine the role and effect of ambroxol in an experimental model of asthma, BALB/c mice were sensitized to ovalbumin (OVA) followed by 3 days of challenge. Airway hyperresponsiveness (AHR), lung cell composition and histology, and cytokine and protein carbonyl levels in bronchoalveolar lavage (BAL) fluid were determined. Ambroxol was administered either before the first OVA challenge or was begun after the last allergen challenge. Cytokine production levels from lung mononuclear cells (Lung MNCs) or alveolar macrophages (AM) were also determined. Administration of ambroxol prior to challenge suppressed AHR, airway eosinophilia, goblet cell metaplasia, and reduced inflammation in subepithelial regions. When given after challenge, AHR was suppressed but without effects on eosinophil numbers. Levels of IL-5 and IL-13 in BAL fluid were decreased when the drug was given prior to challenge; when given after challenge, increased levels of IL-10 and IL-12 were detected. Decreased levels of protein carbonyls were detected in BAL fluid following ambroxol treatment after challenge. In vitro, ambroxol increased levels of IL-10, IFN-γ, and IL-12 from Lung MNCs and AM, whereas IL-4, IL-5, and IL-13 production was not altered. Taken together, ambroxol was effective in preventing AHR and airway inflammation through upregulation of Th1 cytokines and protection from oxidative stress in the airways. PMID:27340385

  5. Solvation force induced by short range, exact dissipative particle dynamics effective surfaces on a simple fluid and on polymer brushes.

    PubMed

    Goicochea, Armando Gama; Alarcón, Francisco

    2011-01-07

    The thermodynamic properties of a simple fluid confined by effective wall forces are calculated using Monte Carlo simulations in the grand canonical ensemble. The solvation force produced by polymer brushes of two different lengths is obtained also. For the particular type of model interactions used, known as the dissipative particle dynamics method, we find that it is possible to obtain an exact, simple expression for the effective force induced by a planar wall composed of identical particles that interact with those in the fluid. We show that despite the short range of all forces in the model, the solvation force can be finite at relatively large distances and therefore does not depend only on the range of the interparticle or solvent-surface forces. As for the polymer brushes, we find that the shape of the solvation force profiles is in fair agreement with scaling and self-consistent field theories. The applications and possible extensions of this work are discussed.

  6. Progenitor Cells in Proximal Airway Epithelial Development and Regeneration

    PubMed Central

    Lynch, Thomas J.; Engelhardt, John F.

    2015-01-01

    Multiple distinct epithelial domains are found throughout the airway that are distinguishable by location, structure, function, and cell-type composition. Several progenitor cell populations in the proximal airway have been identified to reside in confined microenvironmental niches including the submucosal glands (SMGs), which are embedded in the tracheal connective tissue between the surface epithelium and cartilage, and basal cells that reside within the surface airway epithelium (SAE). Current research suggests that regulatory pathways that coordinate development of the proximal airway and establishment of progenitor cell niches may overlap with pathways that control progenitor cell responses during airway regeneration following injury. SMGs have been shown to harbor epithelial progenitor cells, and this niche is dysregulated in diseases such as cystic fibrosis. However, mechanisms that regulate progenitor cell proliferation and maintenance within this glandular niche are not completely understood. Here we discuss glandular progenitor cells during development and regeneration of the proximal airway and compare properties of glandular progenitors to those of basal cell progenitors in the SAE. Further investigation into glandular progenitor cell control will provide a direction for interrogating therapeutic interventions to correct aberrant conditions affecting the SMGs in diseases such as cystic fibrosis, chronic bronchitis, and asthma. PMID:24818588

  7. Settling and deformation of a thin elastic shell on a thin fluid layer lying on a solid surface.

    PubMed

    Chauhan, A; Radke, C J

    2002-01-01

    placement of a soft contact lens onto the cornea, the upper eyelid deforms and settles the lens by squeezing fluid out of the post-lens tear film or POLTF (i.e., the tear fluid layer sandwiched between the lens and the cornea). This paper studies the physical mechanisms that control the dynamic state of the contact lens during blinking, i.e., its shape and its distance from the cornea, especially a long time after insertion. We model the lens as a deformable elastic shell and the cornea as a flat nondeformable body. The tear fluid is assumed to be Newtonian, and the lens is characterized by an elastic modulus and a Poisson ratio. Lubrication equations under creeping flow are used to solve the fluid problem, while the thin-shell approximation is applied to the solid lens. The solid and fluid mechanics problems are coupled by maintaining continuity of stress and velocity at the solid/liquid interface. Lid applied pressure causes the lens to approach the cornea by squeezing tear fluid out and also leads to the deformation of the lens. Subsequently, in the interblink period, since there is no applied force, the elastic energy stored in the lens due to its deformation is released causing it to move away from the cornea by imbibing tear fluid into the POLTF. If the POLTF thickness is large, the inward motion of the lens in the blink is more than the outward motion during interblink, and this causes the lens to settle closer to the cornea. Eventually, there may be a balance of the inward motion during the blink and the outward motion during the interblink. If so, the lens subsequently exhibits periodic steady-state motion. However, it is also possible that a balance of inward and outward motion is never achieved, and the lens continues to settle endlessly. If this happens, then the thinfilm interactions between the mucin-covered corneal surface and the lens material determine whether the lens actually touches the cornea and possibly adheres. Our elastohydrodynamic

  8. Nonlinear vibration of viscoelastic embedded-DWCNTs integrated with piezoelectric layers-conveying viscous fluid considering surface effects

    NASA Astrophysics Data System (ADS)

    Fereidoon, A.; Andalib, E.; Mirafzal, A.

    2016-07-01

    This article studies the nonlinear vibration of viscoelastic embedded nano-sandwich structures containing of a double walled carbon nanotube (DWCNT) integrated with two piezoelectric Zinc oxide (ZnO) layers. DWCNT and ZnO layers are subjected to magnetic and electric fields, respectively. This system is conveying viscous fluid and the related force is calculated by modified Navier-Stokes relation considering slip boundary condition and Knudsen number. Visco-Pasternak model with three parameters of the Winkler modulus, shear modulus, and damp coefficient is used for simulation of viscoelastic medium. The nano-structure is simulated as an orthotropic Timoshenko beam (TB) and the effects of small scale, structural damping and surface stress are considered based on Eringen's, Kelvin-voigt and Gurtin-Murdoch theories. Energy method and Hamilton's principle are employed to derive motion equations which are then solved using differential quadrature method (DQM). The detailed parametric study is conducted, focusing on the combined effects of small scale effect, fluid velocity, thickness of piezoelectric layer, boundary condition, surface effects, van der Waals (vdW) force on the frequency and critical velocity of nano-structure. Results indicate that the frequency and critical velocity increases with assume of surface effects.

  9. One type of hydrodynamic instability in joule heating of a fluid near an ion-selective surface

    NASA Astrophysics Data System (ADS)

    Nikitin, N. V.; Khasmatulina, N. Yu.; Ganchenko, G. S.; Kalaidin, E. N.; Kiriy, V. A.; Demekhin, E. A.

    2016-06-01

    The stability of the equilibrium state of an electrolyte in a horizontal microgap between two ionselective surfaces in an electric field is studied with the Joule heating of the fluid taken into account. It is established that the Joule heating can lead to instability at the potential differences, which are several times smaller than those in the isothermal case. The effects of microscale thermal instability differ from the Rayleigh-Benard thermal convection: the destabilization occurs upon heating in the upper part of the gap.

  10. Magnetic Field and Slip Effects on the Flow and Heat Transfer of Stagnation Point Jeffrey Fluid over Deformable Surfaces

    NASA Astrophysics Data System (ADS)

    Turkyilmazoglu, Mustafa

    2016-06-01

    The Mhd slip flow and heat transfer of stagnation point Jeffrey fluid over deformable surfaces are the state of the art of this article. Following an analytical approach, the existence, uniqueness, and possible multiplicity of the physical solutions affected by several physical parameters are investigated. Particularly, magnetic interaction and slip factor are shown to much influence the structure of the solutions regarding both momentum and thermal boundary layers. The presented exact solutions not only provide a clear understanding of fruitful physical mechanisms present in this nonlinear flow problem but they have also merits in calculations by means of numerous numerical schemes aiming to explore further complex phenomena.

  11. Polymer films removed from solid surfaces by nanostructured fluids: microscopic mechanism and implications for the conservation of cultural heritage.

    PubMed

    Raudino, Martina; Selvolini, Giulia; Montis, Costanza; Baglioni, Michele; Bonini, Massimo; Berti, Debora; Baglioni, Piero

    2015-03-25

    Complex fluids based on amphiphilic formulations are emerging, particularly in the field of conservation of works of art, as effective and safe liquid media for the removal of hydrophobic polymeric coatings. The comprehension of the cleaning mechanism is key to designing tailored fluids for this purpose. However, the interaction between nanostructured fluids and hydrophobic polymer films is still poorly understood. In this study, we show how the combination of confocal laser scanning microscopy (CLSM) and atomic force microscopy (AFM) provides interesting and complementary insight into this process. We focused on the interaction between an ethyl methacrylate/methyl acrylate 70:30 copolymer film deposited onto a glass surface and a water/nonionic surfactant/2-butanone (MEK) ternary system, with MEK being a good solvent and water being a nonsolvent for the polymer. Our results indicate a synergy between the organic solvent and the surfactant assemblies: MEK rapidly swells the outer layers of the polymer film allowing for the subsequent diffusion of solvent molecules, while the amphiphile decreases the interfacial energy between the polymeric coating and the liquid phase, favoring dewetting and dispersion of swollen polymer droplets in the aqueous phase. The chemical nature of the surfactant and the microstructure of the assemblies determine both the kinetics and the overall efficiency of polymer removal, as assessed by comparing the behavior of similar formulations containing an anionic surfactant (sodium dodecyl sulfate, SDS).

  12. Operative endoscopy of the airway

    PubMed Central

    Walters, Dustin M.

    2016-01-01

    Airway endoscopy has long been an important and useful tool in the management of thoracic diseases. As thoracic specialists have gained experience with both flexible and rigid bronchoscopic techniques, the technology has continued to evolve so that bronchoscopy is currently the foundation for diagnosis and treatment of many thoracic ailments. Airway endoscopy plays a significant role in the biopsy of tumors within the airways, mediastinum, and lung parenchyma. Endoscopic methods have been developed to treat benign and malignant airway stenoses and tracheomalacia. And more recently, techniques have been conceived to treat end-stage emphysema and prolonged air leaks in select patients. This review describes the abundant uses of airway endoscopy, as well as technical considerations and limitations of the current technologies. PMID:26981263

  13. Global airway disease beyond allergy.

    PubMed

    Hellings, Peter W; Prokopakis, Emmanuel P

    2010-03-01

    Besides the anatomic continuity of the upper and lower airways, inflammation in one part of the airway influences the homeostasis of the other. The mechanisms underlying this interaction have been studied primarily in allergic disease, showing systemic immune activation, induction of inflammation at a distance, and a negative impact of nasal inflammation on bronchial homeostasis. In addition to allergy, other inflammatory conditions of the upper airways are associated with lower airway disease. Rhinosinusitis is frequently associated with asthma and chronic obstructive pulmonary disease. The impairment of purification, humidification, and warming up of the inspired air by the nose in rhinosinusitis may be responsible in part for bronchial pathology. The resolution of sinonasal inflammation via medical and/or surgical treatment is responsible for the beneficial effect of the treatment on bronchial disease. This article provides a comprehensive overview of the current knowledge of upper and lower airway communication beyond allergic disease.

  14. Recurrent airway obstruction: a review.

    PubMed

    Pirie, R S

    2014-05-01

    Recurrent airway obstruction is a widely recognised airway disorder, characterised by hypersensitivity-mediated neutrophilic airway inflammation and lower airway obstruction in a subpopulation of horses when exposed to suboptimal environments high in airborne organic dust. Over the past decade, numerous studies have further advanced our understanding of different aspects of the disease. These include clarification of the important inhaled airborne agents responsible for disease induction, improving our understanding of the underlying genetic basis of disease susceptibility and unveiling the fundamental immunological mechanisms leading to establishment of the classic disease phenotype. This review, as well as giving a clinical overview of recurrent airway obstruction, summarises much of the work in these areas that have culminated in a more thorough understanding of this debilitating disease.

  15. The airway microbiome and disease.

    PubMed

    Marsland, Benjamin J; Yadava, Koshika; Nicod, Laurent P

    2013-08-01

    Although traditionally thought to be sterile, accumulating evidence now supports the concept that our airways harbor a microbiome. Thus far, studies have focused upon characterizing the bacterial constituents of the airway microbiome in both healthy and diseased lungs, but what perhaps provides the greatest impetus for the exploration of the airway microbiome is that different bacterial phyla appear to dominate diseased as compared with healthy lungs. As yet, there is very limited evidence supporting a functional role for the airway microbiome, but continued research in this direction is likely to provide such evidence, particularly considering the progress that has been made in understanding host-microbe mutualism in the intestinal tract. In this review, we highlight the major advances that have been made discovering and describing the airway microbiome, discuss the experimental evidence that supports a functional role for the microbiome in health and disease, and propose how this emerging field is going to impact clinical practice.

  16. Computational Flow Modeling of Human Upper Airway Breathing

    NASA Astrophysics Data System (ADS)

    Mylavarapu, Goutham

    Computational modeling of biological systems have gained a lot of interest in biomedical research, in the recent past. This thesis focuses on the application of computational simulations to study airflow dynamics in human upper respiratory tract. With advancements in medical imaging, patient specific geometries of anatomically accurate respiratory tracts can now be reconstructed from Magnetic Resonance Images (MRI) or Computed Tomography (CT) scans, with better and accurate details than traditional cadaver cast models. Computational studies using these individualized geometrical models have advantages of non-invasiveness, ease, minimum patient interaction, improved accuracy over experimental and clinical studies. Numerical simulations can provide detailed flow fields including velocities, flow rates, airway wall pressure, shear stresses, turbulence in an airway. Interpretation of these physical quantities will enable to develop efficient treatment procedures, medical devices, targeted drug delivery etc. The hypothesis for this research is that computational modeling can predict the outcomes of a surgical intervention or a treatment plan prior to its application and will guide the physician in providing better treatment to the patients. In the current work, three different computational approaches Computational Fluid Dynamics (CFD), Flow-Structure Interaction (FSI) and Particle Flow simulations were used to investigate flow in airway geometries. CFD approach assumes airway wall as rigid, and relatively easy to simulate, compared to the more challenging FSI approach, where interactions of airway wall deformations with flow are also accounted. The CFD methodology using different turbulence models is validated against experimental measurements in an airway phantom. Two case-studies using CFD, to quantify a pre and post-operative airway and another, to perform virtual surgery to determine the best possible surgery in a constricted airway is demonstrated. The unsteady

  17. Effects of fluid flow on elution of hydrophilic modifier from dialysis membrane surfaces.

    PubMed

    Matsuda, Masato; Sato, Mika; Sakata, Hiroki; Ogawa, Takahisa; Yamamoto, Ken-ichiro; Yakushiji, Taiji; Fukuda, Makoto; Miyasaka, Takehiro; Sakai, Kiyotaka

    2008-01-01

    When uremic blood flows through dialyzers during hemodialysis, dialysis membrane surfaces are exposed to shear stress and internal filtration, which may affect the surface characteristics of the dialysis membranes. In the present study, we evaluated changes in the characteristics of membrane surfaces caused by shear stress and internal filtration using blood substitutes: water purified by reverse osmosis and 6.7 wt% dextran70 solution. We focused on the levels of a hydrophilic modifier, polyvinylpyrrolidone (PVP), on the membrane surface measured by attenuated total reflectance Fourier transform infrared spectroscopy. Experiments involving 4 h dialysis, 0-144 h shear-stress loading, and 4 h dead-end filtration were performed using polyester-polymer alloy (PEPA) and polysulfone (PS) membranes. After the dialysis experiments with accompanying internal filtration, average PVP retention on the PEPA membrane surface was 93.7% in all areas, whereas that on the PS membrane surface was 98.9% in all areas. After the shear-stress loading experiments, PVP retention on the PEPA membrane surface decreased as shear-stress loading time and the magnitude of shear stress increased. However, with the PS membrane, PVP retention scarcely changed. After the dead-end filtration experiments, PVP retention decreased in all areas for both PEPA and PS membranes, but PVP retention on the PEPA membrane surface was lower than that on the PS membrane surface. PVP on the PEPA membrane surface was eluted by both shear stress and internal filtration, while that on the PS membrane surface was eluted only by internal filtration.

  18. The adsorption and lubrication behavior of synovial fluid proteins and glycoproteins on the bearing-surface materials of hip replacements.

    PubMed

    Roba, Marcella; Naka, Marco; Gautier, Emanuel; Spencer, Nicholas D; Crockett, Rowena

    2009-04-01

    The selectivity of synovial fluid protein adsorption onto ultra-high molecular weight polyethylene (UHMWPE) and alumina (Al(2)O(3)), and in particular the ability of glycoproteins to adsorb in the presence of all the other synovial fluid proteins, was investigated by means of fluorescence microscopy and gel electrophoresis (SDS-PAGE). The non-specific nature of protein adsorption from synovial fluid indicated that the lubrication of artificial hip-joint materials may not be attributable to a single protein as has been frequently suggested. The friction behavior of polyethylene (PE) sliding against Al(2)O(3) in solutions of bovine serum albumin (BSA), alpha-1-acid glycoprotein (AGP) and alpha-1-antitrypsin (A1AT) was investigated by means of colloidal probe atomic force microscopy. BSA was shown to be a poorer boundary lubricant than the phosphate buffered saline used as a control. This was attributed to denaturation of the BSA upon adsorption, which provided a high-shear-strength layer at the interface, impairing the lubrication. Interestingly, both the glycoproteins AGP and A1AT, despite their low concentrations, improved lubrication. The lubricating properties of AGP and A1AT were attributed to adsorption via the hydrophobic backbone, allowing the hydrophilic carbohydrate moieties to be exposed to the aqueous solution, thus providing a low-shear-strength fluid film that lubricated the system. The amount of glycoprotein adsorbed on hydrophobic surfaces was determined by means of optical waveguide lightmode spectroscopy (OWLS), allowing conclusions to be drawn about the conformation of the glycan residues following adsorption.

  19. Magnetohydrodynamic Flow and Mass Transfer of a Jeffery Fluid over a Nonlinear Stretching Surface

    NASA Astrophysics Data System (ADS)

    Hayat, Tasawar; Qasim, Muhammad; Abbas, Zaheer; Hendi, Awatif A.

    2010-12-01

    This paper investigates the magnetohydrodynamic (MHD) boundary layer flow of a Jeffery fluid induced by a nonlinearly stretching sheet with mass transfer. The relevant system of partial differential equations has been reduced into ordinary differential equations by employing the similarity transformation. Series solutions of velocity and concentration fields are developed by using the homotopy analysis method (HAM). Effects of the various parameters such as Hartman number, Schmidt number, and chemical reaction parameter on velocity and concentration fields are discussed by presenting graphs. Numerical values of the mass transfer coefficient are also tabulated and analyzed.

  20. Controls of surface topography on submarine and subaerial hydrothermal fluid flow and vent-site location

    NASA Astrophysics Data System (ADS)

    Bani Hassan, N.; Rupke, L.; Iyer, K. H.; Borgia, A.

    2010-12-01

    Hydrothermal convection is an important process that occurs in the oceanic lithosphere as well as within continents where the geothermal gradient is high enough to drive fluid flow. This process efficiently mines heat from the lithosphere, sustains life in the otherwise bleak settings at oceanic depths and is associated with mineral deposits. Although recent focus on hydrothermal systems has greatly improved our understanding on how they work, the detailed effects of topography on these systems has largely been ignored. While the qualitative effects of topography on hydrothermal flow are largely known (e.g. Ingebritsen 2006), we here present results from systematic numerical modeling on the importance of topography for both, subaerial and submarine hydrothermal convection. The model is based on a 2-D Finite Element Method (FEM) solver for fully compressible, single-phase, porous media fluid flow and is used to simulate hydrothermal convection in a number of synthetic studies as well as for two case studies for the Lucky Strike vent field (submarine) and the Amiata volcano (subaerial). The results of synthetic studies using sinusoidal topography variations show that topography indeed has a profound effect on the distribution and flow field of the convection cells. In the submarine case, fluid venting occurs at the topographic highs while the recharge zones are restricted to the lows. For the subaerial scenarios, the opposite occurs where groundwater flow focuses venting at flank regions and the recharge zones are situated at the highs. For example, in the submarine case, ~90% of the hydrothermal fluids vent at upper 50% of topographic highs if the number of topographic highs equals the number of plumes in a flat-top reference simulation. The results show that the focusing effect into topographic highs (submarine) and lows (subaerial) is highly dependent on the wavelength and amplitude of topography, i.e. wavelengths that are too high or low result in venting at

  1. Computational modelling on 2D magnetohydrodynamic flow of Sisko fluid over a time dependent stretching surface

    NASA Astrophysics Data System (ADS)

    Mahmood, T.; Shahzad, A.; Iqbal, Z.; Ahmed, J.; Khan, M.

    A study is presented for the flow and heat transfer of Sisko fluid model over an unsteady stretching sheet in the presence of uniform magnetic field. While taking newly developed similarity transformations, the governing time dependent partial differential equations are reduced to nonlinear ordinary differential equations. Numerical solutions of the reduced nonlinear differential equations are found by employing Shooting method. The influence of physical parameters of interest on the velocity and temperature profiles are highlighted graphically and examined in detail. Moreover, the skin friction coefficient and Nusselt number are tabulated against influential parameters. Skin friction coefficient increases with unsteadiness parameter, magnetic field and suction parameter.

  2. Lysophosphatidylcholine plays critical role in allergic airway disease manifestation

    PubMed Central

    Bansal, Preeti; Gaur, Shailendera Nath; Arora, Naveen

    2016-01-01

    Phospholipase A2 (sPLA2), pivotal for allergic and inflammatory response, hydrolyses phosphatidylcholine (PC) to lysophosphatidylcholine (LPC). In present study, the role of LPC in allergic airway disease manifestation was studied using mouse model. Balb/c mice were immunized using cockroach extract (CE) and LPC release was blocked by sPLA2 inhibitor. Airway hyperresponse (AHR), lung-histology, total and differential leukocyte count (TLC&DLC), Th2 type cytokines, sPLA2 activity and LPC levels in bronchoalveolar lavage fluid (BALF) were measured. Exogenous LPC was given to the mice with or without CE sensitization, to demonstrate its role in allergic airway disease manifestation. Anti-CD1d antibody was given to study the involvement of natural killer T (NKT) cells in LPC induced response. AHR, lung-inflammation, TLC, DLC, Th2 type cytokines, sPLA2 activity and LPC levels were increased on CE challenge. sPLA2 activity and LPC release was blocked by sPLA2-inhibitor, which decreased AHR, and inflammatory parameters. Exogenous LPC with or without CE sensitization increased above parameters. CE challenge or LPC exposure increased LY49C+TCRβ+ NKT cells in BALF and spleen, which was reduced by anti-CD1d antibody, accompanied with reduction in AHR and allergic airway inflammation parameters. Conclusively, LPC induces allergic airway disease manifestation and it does so probably via CD1d-restricted LY49C+TCRβ+ NKT cells. PMID:27282246

  3. Modulating contact angle hysteresis to direct fluid droplets along a homogenous surface.

    PubMed

    Luo, Mingxiang; Gupta, Rohini; Frechette, Joelle

    2012-02-01

    The shape and motion of drops on surfaces is governed by the balance between the driving and the pinning forces. Here we demonstrate control over the motion of droplets on an inclined surface by exerting control over the contact angle hysteresis. The external modulation of contact angle hysteresis is achieved through a voltage-induced local molecular reorganization within the surface film at the solid-liquid interface. We show that tuning contact angle hysteresis alone is sufficient to direct and deform drops when subjected to a constant external driving force, here gravity, in the absence of a pre-defined surface energy gradient or pattern. We also show that the observed stretching and contraction of the drops mimic the motion of an inchworm. Such reversible manipulation of the pinning forces could be an attractive means to direct drops, especially with the dominance of surface forces at micro-/nanoscale.

  4. Lubrication of the human ankle joint in walking with the synovial fluid filtrated by the cartilage with the surface zone worn out: steady pure sliding motion.

    PubMed

    Hlavácek, M

    1999-10-01

    A mixture model of synovial fluid filtration by cartilage in the human ankle joint during walking is presented for steady sliding motion of the articular surfaces. In the paper the cartilage surface zone is assumed worn out. The same model has been recently applied to the squeeze-film problem for the human hip joint loaded by the body weight during standing (Hlavácek, Journal of Biomechanics 26, 1145-1150, 1151-1160, 1993; Hlavácek and Novák, Journal of Biomechanics 28, 1193-1198, 1199-1205, 1995). The linear biphasic model for cartilage (elastic porous matrix + ideal fluid) due to Prof. V. C. Mow and his co-workers and the biphasic model for synovial fluid (viscous fluid + ideal fluid), as used in the above-mentioned squeeze-film problem, are applied. For the physiologic parameters of the ankle joint during walking, a continuous synovial fluid film about 1 microm thick is maintained under steady entraining motion according to the classical model without the fluid transport across the articular surface. This is not the case in the filtration model with the cartilage surface zones worn out. On the contrary, this filtration model indicates that synovial fluid is intensively filtrated by such cartilage, so that no continuous fluid film is maintained and a synovial gel layer, about 10(-8) m thick, develops over the majority of the contact. Thus, if the cartilage surface zones are worn out, boundary lubrication should prevail in the ankle joint under steady sliding motion for the mean values of loading and the sliding velocity encountered in walking cycle.

  5. Surface Waves and Flow-Induced Oscillations along an Underground Elliptic Cylinder Filled with a Viscous Fluid

    NASA Astrophysics Data System (ADS)

    Sakuraba, A.

    2015-12-01

    I made a linear analysis of flow-induced oscillations along an underground cylindrical conduit with an elliptical cross section on the basis of the hypothesis that volcanic tremor is a result of magma movement through a conduit. As a first step to understand how the self oscillation occurs because of magma flow, I investigated surface wave propagation and attenuation along an infinitely long fluid-filled elliptic cylinder in an elastic medium. The boundary element method is used to obtain the two-dimensional wave field around the ellipse in the frequency-wavenumber domain. When the major axis is much greater than the minor axis of the ellipse, we obtain the analytic form of the dispersion relation of both the crack-wave mode (Korneev 2008, Lipovsky & Dunham 2015) and the Rayleigh-wave mode with flexural deformation. The crack-wave mode generally has a slower phase speed and a higher attenuation than the Rayleigh-wave mode. In the long-wavelength limit, the crack-wave mode disappears because of fluid viscosity, but the Rayleigh-wave mode exists with a constant Q-value that depends on viscosity. When the aspect ratio of the ellipse is finite, the surface waves can basically be understood as those propagating along a fluid pipe. The flexural mode does exist even when the wavelength is much longer than the major axis, but its phase speed coincides with that of the surrounding S-wave (Randall 1991). As its attenuation is zero in the long-wavelength limit, the flexural mode differs in nature from surface wave. I also obtain a result on linear stability of viscous flow through an elliptic cylinder. In this analysis, I made an assumption that the fluid inertia is so small that the Stokes equation can be used. As suggested by the author's previous study (Sakuraba & Yamauchi 2014), the flexural (Rayleigh-wave) mode is destabilized at a critical flow speed that decreases with the wavelength. However, when the wavelength is much greater than the major axis of the ellipse, the

  6. A New Formulation for Volume-of-Fluid Simulations of Drops on Solid Surfaces: Inclusion of Adhesion Force

    NASA Astrophysics Data System (ADS)

    Chang, C.; Criscione, A.; Jakirlic, S.; Tropea, C.; Amirfazli, Alidad

    2012-11-01

    The capillary forces acting on a sessile drop placed on a solid surface has two basic components: (1) the Laplace pressure (LP) due to the curvature of the liquid-gas interface, and (2) the Surface Tension Force (STF) as a concentrated force acting at the three-phase contact line. STF can be thought of adhesion force for a drop placed on a solid surface. To date, Volume-of-Fluid (VoF) simulations of drops on solid surfaces have only considered LP, and ignored the STF. Ignoring the STF can lead to incorrect description of the physics for systems involving sessile drops (e.g. shedding of a drop from a surface) especially when capillary and external (e.g. inertial) forces are of the same order of magnitude. Continuum Surface Force (CSF) method is widely used in VoF to model the LP. By modifying the CSF implementation at the contact line, we have added the STF to the VoF formulation. Two case studies, i.e. water drops on an inclined surface and a sessile drop exposed to a shearing airflow are considered. When the STF was ignored, a drop placed on an inclined surface moved at an unrealistically low inclination (e.g. 1 degree for a system with considerable contact angle hysteresis of 10-30 deg.). Same unrealistic motion for the drop was observed when exposed to very low air velocities. Inclusion of the STF corrected both of these unphysical outcomes. A discussion of various systems with different wettabilities (adhesion force values) for each of the two case studies will be provided and comparisons with experiments will be presented.

  7. Transient motion of mucus plugs in respiratory airways

    NASA Astrophysics Data System (ADS)

    Zamankhan, Parsa; Hu, Yingying; Helenbrook, Brian; Takayama, Shuichi; Grotberg, James B.

    2011-11-01

    Airway closure occurs in lung diseases such as asthma, cystic fibrosis, or emphysema which have an excess of mucus that forms plugs. The reopening process involves displacement of mucus plugs in the airways by the airflow of respiration. Mucus is a non-Newtonian fluid with a yield stress; therefore its behavior can be approximated by a Bingham fluid constitutive equation. In this work the reopening process is approximated by simulation of a transient Bingham fluid plug in a 2D channel. The governing equations are solved by an Arbitrary Lagrangian Eulerian (ALE) finite element method through an in-house code. The constitutive equation for the Bingham fluid is implemented through a regularization method. The effects of the yield stress on the flow features and wall stresses are discussed with applications to potential injuries to the airway epithelial cells which form the wall. The minimum driving pressure for the initiation of the motion is computed and its value is related to the mucus properties and the plug shape. Supported by HL84370 and HL85156.

  8. Effect of aerosol propellants and surfactants on airway resistance

    PubMed Central

    Sterling, G. M.; Batten, J. C.

    1969-01-01

    The effects on the airways of inhalation of the vehicles used in two commercial pressurized bronchodilator aerosols were studied in 20 normal and seven asthmatic subjects. Changes in bronchial calibre due to bronchoconstriction were measured as changes in airway resistance using a constant volume whole body plethysmograph, and results were expressed as changes in the ratio Airway conductance/Thoracic gas volume (=specific airway conductance). The aerosols caused very slight bronchoconstriction in the normal subjects, with a mean decrease of 5·3% in specific airway conductance after inhalation of a spray containing sorbitol trioleate as a surface tension lowering agent, and of 9·7% after inhalation of a spray containing lecithin. This effect was prevented by prior inhalation of atropine methonitrate, and its mechanism was therefore probably a vagally mediated reflex. The bronchoconstriction was also reversed by the addition of isoprenaline to the aerosol. The asthmatic subjects showed larger mean reductions in specific airway conductance of 13% and 21% after sorbitol and lecithin respectively: the response was again prevented by atropine. We conclude that, although the aerosol vehicles cause slight bronchoconstriction, this is unlikely to be a clinical danger since it is insufficient to cause symptoms of wheezing, and is less than that caused by inhalation of a single cigarette. Moreover, the constriction is regularly converted to dilatation in both normal and asthmatic subjects by the addition of atropine or isoprenaline to the aerosol. PMID:5821624

  9. Small airways involvement in coal mine dust lung disease.

    PubMed

    Long, Joshua; Stansbury, Robert C; Petsonk, Edward L

    2015-06-01

    Inhalation of coal mine dust results in a spectrum of symptoms, dysfunction, and pathological changes in the respiratory tract that collectively have been labeled coal mine dust lung disease. Recent reports from periodic health surveillance among underground and surface coal miners in the United States have demonstrated an increasing prevalence and severity of dust diseases, and have also documented that some miners experience rapid disease progression. The coal macule is an inflammatory lesion associated with deposited dust, and occurs in the region of the most distal conducting airways and proximal respiratory bronchioles. Inflammatory changes in the small airways have long been recognized as the signature lung pathology among coal miners. Human and laboratory studies have suggested oxidant injury, and increased recruitment and activity of macrophages play important roles in dust-induced lung injury. However, the functional importance of the small airway changes was debated for many years. We reviewed published literature that documents a pervasive occurrence of both physiologic and structural abnormalities in small airways among coal miners and other workers exposed to airborne particulates. There is increasing evidence supporting an important association of abnormalities in the small peripheral airways with the development of respiratory symptoms, deficits in spirometry values, and accelerated declines in ventilatory lung function. Pathologic changes associated with mineral dust deposition in the small airways may be of particular importance in contemporary miners with rapidly progressive respiratory impairment.

  10. Airway drug pharmacokinetics via analysis of exhaled breath condensate.

    PubMed

    Esther, Charles R; Boucher, Richard C; Johnson, M Ross; Ansede, John H; Donn, Karl H; O'Riordan, Thomas G; Ghio, Andrew J; Hirsh, Andrew J

    2014-02-01

    Although the airway surface is the anatomic target for many lung disease therapies, measuring drug concentrations and activities on these surfaces poses considerable challenges. We tested whether mass spectrometric analysis of exhaled breath condensate (EBC) could be utilized to non-invasively measure airway drug pharmacokinetics and predicted pharmacological activities. Mass spectrometric methods were developed to detect a novel epithelial sodium channel blocker (GS-9411/P-680), two metabolites, a chemically related internal standard, plus naturally occurring solutes including urea as a dilution marker. These methods were then applied to EBC and serum collected from four (Floridian) sheep before, during and after inhalation of nebulized GS-9411/P-680. Electrolyte content of EBC and serum was also assessed as a potential pharmacodynamic marker of drug activity. Airway surface concentrations of drug, metabolites, and electrolytes were calculated from EBC measures using EBC:serum urea based dilution factors. GS-9411/P-680 and its metabolites were quantifiable in the sheep EBC, with peak airway concentrations between 1.9 and 3.4 μM measured 1 h after inhalation. In serum, only Metabolite #1 was quantifiable, with peak concentrations ∼60-fold lower than those in the airway (45 nM at 1 h). EBC electrolyte concentrations suggested a pharmacological effect; but this effect was not statistical significant. Analysis of EBC collected during an inhalation drug study provided a method for quantification of airway drug and metabolites via mass spectrometry. Application of this methodology could provide an important tool in development and testing of drugs for airways diseases.

  11. Crystallization processes at the surface of polylactic acid-bioactive glass composites during immersion in simulated body fluid.

    PubMed

    Ginsac, Nathalie; Chenal, Jean-Marc; Meille, Sylvain; Pacard, Elodie; Zenati, Rachid; Hartmann, Daniel J; Chevalier, Jérôme

    2011-11-01

    We report on the crystallization processes occurring at the surface of PDLLA-Bioglass® composites immersed in simulated body fluid. Composites manufactured by injection molding and containing different amounts (0, 20, 30, and 50 wt %) of 45S5 Bioglass® particles were tested for durations up to 56 days and compared with Bioglass® particles alone. Crystallization processes were followed by visual inspection, X-ray diffraction (with Rietveld analysis) and scanning electron microscopy. Both calcite and hydroxyapatite were formed at the surface of all materials, but their relative ratio was dependent on the Bioglass® content and immersion time. Hydroxyapatite was always the major phase after sufficient immersion time, insuring bioactivity of such composites especially for Bioglass® content higher than 30 wt %. A scenario of crystallization is proposed. Rapid degradation of the composites with 50 wt % was also observed during immersion. Therefore, composites with 30 wt % of Bioglass® particles seem to exhibit the best balance between bioactivity and stability at least during the first weeks of immersion in contact with body fluids.

  12. Finite amplitude vibrations of a sharp-edged beam immersed in a viscous fluid near a solid surface

    NASA Astrophysics Data System (ADS)

    Grimaldi, Emma; Porfiri, Maurizio; Soria, Leonardo

    2012-11-01

    In this paper, we study finite amplitude bending vibrations of a slender thin beam immersed in a quiescent viscous liquid and oscillating near a solid surface. We focus on the regime of low Knudsen and squeeze numbers and moderately large Keulegan-Carpenter number, for which neither squeeze film models nor unsteady Stokes hydrodynamics are suitable to describe the flow physics. In this case, the distributed hydrodynamic loading experienced by the oscillating beam is represented by a complex-valued hydrodynamic function, which explicitly depends on the Keulegan-Carpenter number to account for convection-driven nonlinearities in the fluid-structure interaction. We conduct a parametric study on the two-dimensional computational fluid dynamics of a rigid lamina oscillating in the vicinity of a solid surface to establish a handleable semianalytical formula for the hydrodynamic function in terms of the key nondimensional parameters. We validate the proposed modeling approach through experiments on centimeter-size compliant cantilevers vibrating underwater under base excitation at varying distances from a rigid wall.

  13. Altered Epithelial Gene Expression in Peripheral Airways of Severe Asthma

    PubMed Central

    Singhania, Akul; Rupani, Hitasha; Jayasekera, Nivenka; Lumb, Simon; Hales, Paul; Gozzard, Neil; Davies, Donna E.

    2017-01-01

    Management of severe asthma remains a challenge despite treatment with glucocorticosteroid therapy. The majority of studies investigating disease mechanisms in treatment-resistant severe asthma have previously focused on the large central airways, with very few utilizing transcriptomic approaches. The small peripheral airways, which comprise the majority of the airway surface area, remain an unexplored area in severe asthma and were targeted for global epithelial gene expression profiling in this study. Differences between central and peripheral airways were evaluated using transcriptomic analysis (Affymetrix HG U133 plus 2.0 GeneChips) of epithelial brushings obtained from severe asthma patients (N = 17) and healthy volunteers (N = 23). Results were validated in an independent cohort (N = 10) by real-time quantitative PCR. The IL-13 disease signature that is associated with an asthmatic phenotype was upregulated in severe asthmatics compared to healthy controls but was predominantly evident within the peripheral airways, as were genes related to mast cell presence. The gene expression response associated with glucocorticosteroid therapy (i.e. FKBP5) was also upregulated in severe asthmatics compared to healthy controls but, in contrast, was more pronounced in central airways. Moreover, an altered epithelial repair response (e.g. FGFBP1) was evident across both airway sites reflecting a significant aspect of disease in severe asthma unadressed by current therapies. A transcriptomic approach to understand epithelial activation in severe asthma has thus highlighted the need for better-targeted therapy to the peripheral airways in severe asthma, where the IL-13 disease signature persists despite treatment with currently available therapy. PMID:28045928

  14. Altered Epithelial Gene Expression in Peripheral Airways of Severe Asthma.

    PubMed

    Singhania, Akul; Rupani, Hitasha; Jayasekera, Nivenka; Lumb, Simon; Hales, Paul; Gozzard, Neil; Davies, Donna E; Woelk, Christopher H; Howarth, Peter H

    2017-01-01

    Management of severe asthma remains a challenge despite treatment with glucocorticosteroid therapy. The majority of studies investigating disease mechanisms in treatment-resistant severe asthma have previously focused on the large central airways, with very few utilizing transcriptomic approaches. The small peripheral airways, which comprise the majority of the airway surface area, remain an unexplored area in severe asthma and were targeted for global epithelial gene expression profiling in this study. Differences between central and peripheral airways were evaluated using transcriptomic analysis (Affymetrix HG U133 plus 2.0 GeneChips) of epithelial brushings obtained from severe asthma patients (N = 17) and healthy volunteers (N = 23). Results were validated in an independent cohort (N = 10) by real-time quantitative PCR. The IL-13 disease signature that is associated with an asthmatic phenotype was upregulated in severe asthmatics compared to healthy controls but was predominantly evident within the peripheral airways, as were genes related to mast cell presence. The gene expression response associated with glucocorticosteroid therapy (i.e. FKBP5) was also upregulated in severe asthmatics compared to healthy controls but, in contrast, was more pronounced in central airways. Moreover, an altered epithelial repair response (e.g. FGFBP1) was evident across both airway sites reflecting a significant aspect of disease in severe asthma unadressed by current therapies. A transcriptomic approach to understand epithelial activation in severe asthma has thus highlighted the need for better-targeted therapy to the peripheral airways in severe asthma, where the IL-13 disease signature persists despite treatment with currently available therapy.

  15. Hyaluronan mediates airway hyperresponsiveness in oxidative lung injury

    PubMed Central

    Lazrak, Ahmed; Creighton, Judy; Yu, Zhihong; Komarova, Svetlana; Doran, Stephen F.; Aggarwal, Saurabh; Emala, Charles W.; Stober, Vandy P.; Trempus, Carol S.; Garantziotis, Stavros

    2015-01-01

    Chlorine (Cl2) inhalation induces severe oxidative lung injury and airway hyperresponsiveness (AHR) that lead to asthmalike symptoms. When inhaled, Cl2 reacts with epithelial lining fluid, forming by-products that damage hyaluronan, a constituent of the extracellular matrix, causing the release of low-molecular-weight fragments (L-HA, <300 kDa), which initiate a series of proinflammatory events. Cl2 (400 ppm, 30 min) exposure to mice caused an increase of L-HA and its binding partner, inter-α-trypsin-inhibitor (IαI), in the bronchoalveolar lavage fluid. Airway resistance following methacholine challenge was increased 24 h post-Cl2 exposure. Intratracheal administration of high-molecular-weight hyaluronan (H-HA) or an antibody against IαI post-Cl2 exposure decreased AHR. Exposure of human airway smooth muscle (HASM) cells to Cl2 (100 ppm, 10 min) or incubation with Cl2-exposed H-HA (which fragments it to L-HA) increased membrane potential depolarization, intracellular Ca2+, and RhoA activation. Inhibition of RhoA, chelation of intracellular Ca2+, blockade of cation channels, as well as postexposure addition of H-HA, reversed membrane depolarization in HASM cells. We propose a paradigm in which oxidative lung injury generates reactive species and L-HA that activates RhoA and Ca2+ channels of airway smooth muscle cells, increasing their contractility and thus causing AHR. PMID:25747964

  16. A new technique for surface and shallow subsurface paleobarometry using fluid inclusions: An example from the Upper Ordovician Viola Formation, Kansas, USA

    USGS Publications Warehouse

    Newell, K.D.; Goldstein, R.H.

    1999-01-01

    This research illustrates a new approach for paleobarometry employing heterogeneously entrapped fluid inclusions to determine timing and depth of diagenesis. Heterogeneously entrapped fluid inclusions (gas + water) in vug-filling quartz from the Upper Ordovician Viola Formation in the Midcontinent of the United States were analyzed for their internal pressure with a fluid-inclusion crushing stage. The free gas in fluid inclusions was entrapped at near-surface temperature, as indicated by the presence of all-liquid fluid inclusions and fluid inclusions with low homogenization temperatures ( <40??C). Crushing the crystal and measuring the change in bubble size determines the pressure of entrapment directly. Heterogeneous trapping is indicated by widely varying L:V ratios, from all-liquid to vapor-rich. Gas bubbles in most fluid inclusions analyzed expanded upon release to atmospheric pressure, but some collapsed. A mode of 1.5 to 2.0 atm internal pressure was indicated by the crushing runs, but pressures up to 42.9 atm were recorded. Quartz precipitation and associated fluid-inclusion entrapment therefore occurred over a wide depth-range, but principally at depths of approximately 10 m. Crushing runs done in kerosene confirmed the presence of hydrocarbon gases in most of these inclusions, and bulk analyses of gases in the quartz by quadrupole mass spectrometer revealed methane, ethane, and atmospheric gases. The hydrocarbon gases may have originated in deeper thermogenically mature sedimentary strata, and then leaked to the near-surface where they were entrapped in the precipitating quartz cement. Freezing data indicate an event of quartz precipitation from fluids of marine-fresh water intermediate salinity and other events of precipitation from more saline fluids. Considering the determined pressures, the precipitating fluids probably originated at surfaces of subaerial exposure (unconformities) and surfaces of evaporite precipitation in the overlying Silurian

  17. Solid particles adsorbed on capillary-bridge-shaped fluid polystyrene surfaces.

    PubMed

    McEnnis, Kathleen; Dinsmore, Anthony D; Russell, Thomas P

    2015-05-19

    Particles adsorbed on microscopic polystyrene (PS) capillary bridge surfaces were observed to investigate their motion under capillary forces arising from a nonuniform shape. Capillary bridges were created by placing thin PS films, heated above the glass transition temperature (Tg), between two electrodes with an air gap between the surface of the PS and the upper electrode. Silica particles, 100 nm in diameter, were placed on the surface of the PS capillary bridges, and the sample was heated above the Tg of PS to enable particle motion. Samples were cooled to below Tg, and the locations of the particles were observed using scanning electron microscopy. The particles did not preferentially locate around the center of the capillary bridge, as predicted by others, but instead segregated to the edges. These results indicate that the forces driving particles to the three-phase contact line (air/PS/electrode surface) are greater than those locating particles around the center.

  18. Effect of fluid viscosity on surface patterns formed by gravitational instability

    NASA Astrophysics Data System (ADS)

    Shimokawa, Michiko; Takami, Toshiya

    2015-12-01

    When a droplet of a higher-density solution (HDS) is placed on the top of a lower-density solution (LDS), the HDS on the surface of the LDS sinks due to gravitational instability. In the sinking process, the HDS draws a fractal pattern or a hole/cell pattern on the surface of the LDS. It is observed that the surface pattern is determined by an aspect ratio of the container and viscosity of the LDS. In the formation of the surface pattern, a time series of the HDS density is analyzed. It is found that the profile of the series for the fractal pattern is different from that for the hole/cell pattern. In order to clarify the difference, we propose a phenomenological model for the time series to obtain fitting functions for both patterns.

  19. AFM fluid delivery/liquid extraction surface sampling/electrostatic spray cantilever probe

    SciTech Connect

    Van Berkel, Gary J.

    2015-06-23

    An electrospray system comprises a liquid extraction surface sampling probe. The probe comprises a probe body having a liquid inlet and a liquid outlet, and having a liquid extraction tip. A solvent delivery conduit is provided for receiving solvent liquid from the liquid inlet and delivering the solvent liquid to the liquid extraction tip. An open liquid extraction channel extends across an exterior surface of the probe body from the liquid extraction tip to the liquid outlet. An electrospray emitter tip is in liquid communication with the liquid outlet of the liquid extraction surface sampling probe. A system for analyzing samples, a liquid junction surface sampling system, and a method of analyzing samples are also disclosed.

  20. A hybrid method for airway segmentation and automated measurement of bronchial wall thickness on CT.

    PubMed

    Xu, Ziyue; Bagci, Ulas; Foster, Brent; Mansoor, Awais; Udupa, Jayaram K; Mollura, Daniel J

    2015-08-01

    Inflammatory and infectious lung diseases commonly involve bronchial airway structures and morphology, and these abnormalities are often analyzed non-invasively through high resolution computed tomography (CT) scans. Assessing airway wall surfaces and the lumen are of great importance for diagnosing pulmonary diseases. However, obtaining high accuracy from a complete 3-D airway tree structure can be quite challenging. The airway tree structure has spiculated shapes with multiple branches and bifurcation points as opposed to solid single organ or tumor segmentation tasks in other applications, hence, it is complex for manual segmentation as compared with other tasks. For computerized methods, a fundamental challenge in airway tree segmentation is the highly variable intensity levels in the lumen area, which often causes a segmentation method to leak into adjacent lung parenchyma through blurred airway walls or soft boundaries. Moreover, outer wall definition can be difficult due to similar intensities of the airway walls and nearby structures such as vessels. In this paper, we propose a computational framework to accurately quantify airways through (i) a novel hybrid approach for precise segmentation of the lumen, and (ii) two novel methods (a spatially constrained Markov random walk method (pseudo 3-D) and a relative fuzzy connectedness method (3-D)) to estimate the airway wall thickness. We evaluate the performance of our proposed methods in comparison with mostly used algorithms using human chest CT images. Our results demonstrate that, on publicly available data sets and using standard evaluation criteria, the proposed airway segmentation method is accurate and efficient as compared with the state-of-the-art methods, and the airway wall estimation algorithms identified the inner and outer airway surfaces more accurately than the most widely applied methods, namely full width at half maximum and phase congruency.

  1. Putting the Squeeze on Airway Epithelia

    PubMed Central

    Park, Jin-Ah; Fredberg, Jeffrey J.

    2015-01-01

    Asthma is characterized by chronic inflammation, airway hyperresponsiveness, and progressive airway remodeling. The airway epithelium is known to play a critical role in the initiation and perpetuation of these processes. Here, we review how excessive epithelial stress generated by bronchoconstriction is sufficient to induce airway remodeling, even in the absence of inflammatory cells. PMID:26136543

  2. AANA journal course: update for nurse anesthetists. The SLAM Emergency Airway Flowchart: a new guide for advanced airway practitioners.

    PubMed

    Rich, James M; Mason, Andrew M; Ramsay, Michael A E

    2004-12-01

    Advanced airway practitioners in anesthesiology, emergency medicine, and prehospital care can suddenly and unexpectedly face difficult airway situations that can surface without warning during mask ventilation or tracheal intubation. Although tracheal intubation remains the "gold standard" in airway management, it is not always achievable, and, when it proves impossible, appropriate alternative interventions must be used rapidly to avoid serious morbidity or mortality. The SLAM Emergency Airway Flowchart (SEAF) is intended to prevent the 3 reported primary causes of adverse respiratory events (ie, inadequate ventilation, undetected esophageal intubation, and difficult intubation). The 5 pathways of the SEAF include primary ventilation, rapid-sequence intubation, difficult intubation, rescue ventilation, and cricothyrotomy. It is intended for use with adult patients by advanced airway practitioners competent in direct laryngoscopy, tracheal intubation, administration of airway drugs, rescue ventilation, and cricothyrotomy. The SEAF has limitations (eg, suitable only for use with adult patients, cannot be used by certain categories of rescue personnel, and depends heavily on assessment of Spo2). A unique benefit is provision of simple alternative techniques that can be used when another technique fails.

  3. Effect of Joule Heating and Thermal Radiation in Flow of Third Grade Fluid over Radiative Surface

    PubMed Central

    Hayat, Tasawar; Shafiq, Anum; Alsaedi, Ahmed

    2014-01-01

    This article addresses the boundary layer flow and heat transfer in third grade fluid over an unsteady permeable stretching sheet. The transverse magnetic and electric fields in the momentum equations are considered. Thermal boundary layer equation includes both viscous and Ohmic dissipations. The related nonlinear partial differential system is reduced first into ordinary differential system and then solved for the series solutions. The dependence of velocity and temperature profiles on the various parameters are shown and discussed by sketching graphs. Expressions of skin friction coefficient and local Nusselt number are calculated and analyzed. Numerical values of skin friction coefficient and Nusselt number are tabulated and examined. It is observed that both velocity and temperature increases in presence of electric field. Further the temperature is increased due to the radiation parameter. Thermal boundary layer thickness increases by increasing Eckert number. PMID:24454694

  4. Effect of Joule heating and thermal radiation in flow of third grade fluid over radiative surface.

    PubMed

    Hayat, Tasawar; Shafiq, Anum; Alsaedi, Ahmed

    2014-01-01

    This article addresses the boundary layer flow and heat transfer in third grade fluid over an unsteady permeable stretching sheet. The transverse magnetic and electric fields in the momentum equations are considered. Thermal boundary layer equation includes both viscous and Ohmic dissipations. The related nonlinear partial differential system is reduced first into ordinary differential system and then solved for the series solutions. The dependence of velocity and temperature profiles on the various parameters are shown and discussed by sketching graphs. Expressions of skin friction coefficient and local Nusselt number are calculated and analyzed. Numerical values of skin friction coefficient and Nusselt number are tabulated and examined. It is observed that both velocity and temperature increases in presence of electric field. Further the temperature is increased due to the radiation parameter. Thermal boundary layer thickness increases by increasing Eckert number.

  5. Airway mucus: From production to secretion.

    PubMed

    Williams, Olatunji W; Sharafkhaneh, Amir; Kim, Victor; Dickey, Burton F; Evans, Christopher M

    2006-05-01

    Mucus hypersecretion is a phenotype associated with multiple obstructive lung diseases. However, in spite of its nefarious reputation under pathologic conditions, there are significant benefits to having low levels of mucus present in the airways at baseline, such as the ability to trap and eliminate inhaled particles and to prevent desiccation of airway surfaces. Mucins are high-molecular-weight glycoproteins that are the chief components that render viscoelastic and gel-forming properties to mucus. Recent advances in animal models and in vitro systems have provided a wealth of information regarding the identification of the mucin genes that are expressed in the lungs, the signal transduction pathways that regulate the expression of these mucins, and the secretory pathways that mediate their release into the airways. In addition, the clinical and pathologic literature has corroborated many of the basic laboratory findings. As a result, mucin overproduction and hypersecretion are moving away from being markers of disease and toward being testable as functional components of lung disease processes.

  6. Exercise and airway injury in athletes.

    PubMed

    Couto, Mariana; Silva, Diana; Delgado, Luis; Moreira, André

    2013-01-01

    Olympic level athletes present an increased risk for asthma and allergy, especially those who take part in endurance sports, such as swimming or running, and in winter sports. Classical postulated mechanisms behind EIA include the osmotic, or airway-drying, hypothesis. Hyperventilation leads to evaporation of water and the airway surface liquid becomes hyperosmolar, providing a stimulus for water to move from any cell nearby, which results in the shrinkage of cells and the consequent release of inflammatory mediators that cause airway smooth muscle contraction. But the exercise-induced asthma/bronchoconstriction explanatory model in athletes probably comprises the interaction between environmental training factors, including allergens and ambient conditions such as temperature, humidity and air quality; and athlete's personal risk factors, such as genetic and neuroimmuneendocrine determinants. After the stress of training and competitions athletes experience higher rate of upper respiratory tract infections (URTI), compared with lesser active individuals. Increasing physical activity in non-athletes is associated with a decreased risk of URTI. Heavy exercise induces marked immunodepression which is multifactorial in origin. Prolonged, high intensity exercise temporarily impairs the immune competence while moderate activity may enhance immune function. The relationship between URTI and exercise is affected by poorly known individual determinants such genetic susceptibility, neurogenic mediated immune inflammation and epithelial barrier dysfunction. Further studies should better define the aetiologic factors and mechanisms involved in the development of asthma in athletes, and propose relevant preventive and therapeutic measures.

  7. Effect of P2X4R on airway inflammation and airway remodeling in allergic airway challenge in mice

    PubMed Central

    CHEN, HONGXIA; XIA, QINGQING; FENG, XIAOQIAN; CAO, FANGYUAN; YU, HANG; SONG, YINLI; NI, XIUQIN

    2016-01-01

    P2X4 receptor (P2X4R) is the most widely expressed subtype of the P2XRs in the purinergic receptor family. Adenosine triphosphate (ATP), a ligand for this receptor, has been implicated in the pathogenesis of asthma. ATP-P2X4R signaling is involved in pulmonary vascular remodeling, and in the proliferation and differentiation of airway and alveolar epithelial cell lines. However, the role of P2X4R in asthma remains to be elucidated. This aim of the present study was to investigate the effects of P2X4R in a murine experimental asthma model. The asthmatic model was established by the inhalation of ovalbumin (OVA) in BALB/c mice. The mice were treated with P2X4R-specific agonists and antagonists to investigate the role of this receptor in vivo. Pathological changes in the bronchi and lung tissues were examined using hematoxylin and eosin staining, Masson's trichrome staining and Alcian blue staining. The inflammatory cells in the bronchoalveolar lavage fluid were counted, and the expression levels of P2X4R, α-smooth muscle actin (α-SMA) and proliferating cell nuclear antigen (PCNA) were detected using western blotting. In the OVA-challenged mice, inflammation, infiltration, collagen deposition, mucus production, and the expression levels of P2X4R and PCNA were all increased; however, the expression of α-SMA was decreased, compared with the mice in the control group. Whereas treatment with the P2X4R agonist, ATP, enhanced the allergic reaction, treatment with the P2X4R antagonist, 5-BDBD, attenuated the allergic reaction. The results suggested that ATP-P2X4R signaling may not only contribute to airway inflammation, but it may also contribute to airway remodeling in allergic asthma in mice. PMID:26648454

  8. Grepafloxacin inhibits tumor necrosis factor-alpha-induced interleukin-8 expression in human airway epithelial cells.

    PubMed

    Hashimoto, S; Matsumoto, K; Gon, Y; Maruoka, S; Hayashi, S; Asai, Y; Machino, T; Horie, T

    2000-01-01

    We examined the effect of grepafloxacin (GPFX), a new fluoroquinolone antimicrobial agent, on interleukin-8 (IL-8) expression in tumor necrosis factor-alpha (TNF-alpha)-stimulated human airway epithelial cells (AEC). GPFX inhibited IL-8 protein production as well as mRNA expression in a concentration-dependent manner (2.5 - 25 micro g/ml), but the inhibition of IL-8 expression by corresponding concentrations of GPFX to serum and airway lining fluids was not complete. We discuss the modulatory effect of GPFX on IL-8 production in the context of its efficacy on controlling chronic airway inflammatory diseases.

  9. Nonlocal and surface effects on the flutter instability of cantilevered nanotubes conveying fluid subjected to follower forces

    NASA Astrophysics Data System (ADS)

    Bahaadini, Reza; Hosseini, Mohammad; Jamalpoor, Ali

    2017-03-01

    On the basis of nonlocal elasticity theory, this paper studies the dynamic structural instability behavior of cantilever nanotubes conveying fluid incorporating end concentrated follower force and distributed tangential load, resting on the visco-Pasternak substrate. In order to improve the accuracy of the results, surface effects, i.e. surface elasticity and residual stresses are considered. Extended Hamilton's principle is implemented to obtain the nonlocal governing partial differential equation and related boundary conditions. Then, the extended Galerkin technique is used to convert partial differential equations into a general set of ordinary differential equations. Numerical results are expressed to reveal the variations of the critical flow velocity for flutter phenomenon of cantilever nanotubes with the various values of nonlocal parameter, mass ratios, nanotubes thickness, surface effects, various parameters of the visco-Pasternak medium, constant follower force and distributed compressive tangential load. Some numerical results of this research illustrated that the values of critical flutter flow velocity and stable region increase by considering surface effects. Also, critical flutter flow velocity decreases towards zero by increasing the value of the distributed compressive tangential load and constant follower force.

  10. Tribological investigation of diamond-like carbon coated micro-dimpled surface under bovine serum and osteoarthritis oriented synovial fluid

    PubMed Central

    Ghosh, Subir; Choudhury, Dipankar; Roy, Taposh; Bin Mamat, Azuddin; Masjuki, H H; Pingguan-Murphy, Belinda

    2015-01-01

    Osteoarthritis-oriented synovial fluid (OASF), i.e., that typical of a patient with osteoarthritis, has different physical and biological characteristics than bovine serum (BS), a lubricant widely used in biotribological investigations. Micro-dimpled and diamond-like carbon- (DLC) coated surfaces are key emerging interfaces for orthopedic implants. In this study, tribological performances of dimpled surfaces, with and without DLC coating, have been investigated under both BS and OASF. The friction tests were performed utilizing a pin on a disk tribometer, whereas contact pressure, speed, and temperature were simulated to a ‘medium walking gait’ of hip joint conditions. The mechanical properties of the specimen and the physical properties of the lubricant were characterized before the friction test. Raman analysis was conducted to identify the coating condition both before and after the test. The DLC-coated dimpled surface showed maximum hardness and residual stress. A DLC-coated dimpled surface under an OASF lubricated condition yielded a lower friction coefficient and wear compared to those of plain and dimpled specimens. The higher graphitization of coated materials with increasing load was confirmed by Raman spectroscopy. PMID:27877803

  11. Tribological investigation of diamond-like carbon coated micro-dimpled surface under bovine serum and osteoarthritis oriented synovial fluid

    NASA Astrophysics Data System (ADS)

    Ghosh, Subir; Choudhury, Dipankar; Roy, Taposh; Mamat, Azuddin Bin; Masjuki, H. H.; Pingguan-Murphy, Belinda

    2015-06-01

    Osteoarthritis-oriented synovial fluid (OASF), i.e., that typical of a patient with osteoarthritis, has different physical and biological characteristics than bovine serum (BS), a lubricant widely used in biotribological investigations. Micro-dimpled and diamond-like carbon- (DLC) coated surfaces are key emerging interfaces for orthopedic implants. In this study, tribological performances of dimpled surfaces, with and without DLC coating, have been investigated under both BS and OASF. The friction tests were performed utilizing a pin on a disk tribometer, whereas contact pressure, speed, and temperature were simulated to a ‘medium walking gait’ of hip joint conditions. The mechanical properties of the specimen and the physical properties of the lubricant were characterized before the friction test. Raman analysis was conducted to identify the coating condition both before and after the test. The DLC-coated dimpled surface showed maximum hardness and residual stress. A DLC-coated dimpled surface under an OASF lubricated condition yielded a lower friction coefficient and wear compared to those of plain and dimpled specimens. The higher graphitization of coated materials with increasing load was confirmed by Raman spectroscopy.

  12. Design of an experimental apparatus for measurement of the surface tension of metastable fluids

    NASA Astrophysics Data System (ADS)

    Vinš, V.; Hrubý, J.; Hykl, J.; Blaha, J.; Šmíd, B.

    2013-04-01

    A unique experimental apparatus for measurement of the surface tension of aqueous mixtures has been designed, manufactured, and tested in our laboratory. The novelty of the setup is that it allows measurement of surface tension by two different methods: a modified capillary elevation method in a long vertical capillary tube and a method inspired by the approach of Hacker (National Advisory Committee for Aeronautics, Technical Note 2510, 1-20, 1951), i.e. in a short horizontal capillary tube. Functionality of all main components of the apparatus, e.g., glass chamber with the capillary tube, temperature control unit consisting of two thermostatic baths with special valves for rapid temperature jumps, helium distribution setup allowing pressure variation above the liquid meniscus inside the capillary tube, has been successfully tested. Preliminary results for the surface tension of the stable and metastable supercooled water measured by the capillary elevation method at atmospheric pressure are provided. The surface tension of water measured at temperatures between +26 °C and -11 °C is in good agreement with the extrapolated IAPWS correlation (IAPWS Release on Surface Tension of Ordinary Water Substance, September 1994); however it disagrees with data by Hacker.

  13. Airway complications after lung transplantation.

    PubMed

    Machuzak, Michael; Santacruz, Jose F; Gildea, Thomas; Murthy, Sudish C

    2015-01-01

    Airway complications after lung transplantation present a formidable challenge to the lung transplant team, ranging from mere unusual images to fatal events. The exact incidence of complications is wide-ranging depending on the type of event, and there is still evolution of a universal characterization of the airway findings. Management is also wide-ranging. Simple observation or simple balloon bronchoplasty is sufficient in many cases, but vigilance following more severe necrosis is required for late development of both anastomotic and nonanastomotic airway strictures. Furthermore, the impact of coexisting infection, rejection, and medical disease associated with high-level immunosuppression further complicates care.

  14. Gene Delivery to the Airway

    PubMed Central

    Keiser, Nicholas W.; Engelhardt, John F.

    2013-01-01

    This unit describes generation of and gene transfer to several commonly used airway models. Isolation and transduction of primary airway epithelial cells are first described. Next, the preparation of polarized airway epithelial monolayers is outlined. Transduction of these polarized cells is also described. Methods are presented for generation of tracheal xenografts as well as both ex vivo and in vivo gene transfer to these xenografts. Finally, a method for in vivo gene delivery to the lungs of rodents is included. Methods for evaluating transgene expression are given in the support protocols. PMID:23853081

  15. Formation of caries-like lesions in vitro on the root surfaces of human teeth in solutions simulating plaque fluid.

    PubMed

    Shellis, R P

    2010-01-01

    Lesion formation on root surfaces of human posterior teeth was studied in acetate/lactate buffers with a background electrolyte composition based on plaque fluid analyses. Lesion depth after 28 days at 37 degrees C was measured in relation to: the presence or absence of cementum; the concentration of undissociated buffer; the presence or absence of magnesium ions at plaque fluid concentration. Each factor was evaluated at several values of -log(ion activity product for hydroxyapatite): pI(HA). Solutions were formulated to minimize variation in pH, which varied by < or =0.03 for a given comparison (individual pI(HA)) and by 0.42-0.82 over the range of pI(HA) within experiments. Lesions on surfaces from which cementum had been ground were significantly deeper than on intact surfaces, but this is considered to be due to subsurface mechanical damage and not to a solubility difference. Neither the concentration of undissociated buffer nor the presence of magnesium ions significantly affected lesion depth. Lesion depth was strongly influenced by the correlated variations in pI(HA) and pH. At pI(HA) 54 and 55, only extremely shallow lesions formed. From pI(HA) 56, lesion depth increased with increasing pI(HA). The results confirm that the solubility of the mineral of root tissues is higher than that of hydroxyapatite, but indicate that it is probably lower than suggested by Hoppenbrouwers et al. [Arch Oral Biol 1987;32:319-322]. For calcium concentrations of 3-12 mM, the critical pH for root tissue mineral was calculated as 5.22-5.66 assuming solubility equivalent to pI(HA) 54 and 5.08-5.51 assuming pI(HA) 55.

  16. Elastically driven surface plumes in rimming flow of a non-Newtonian fluid.

    PubMed

    Seiden, Gabriel; Steinberg, Victor

    2012-11-01

    A polymer solution partially filling a rotating horizontal drum undergoes an elastically driven instability at low Reynolds numbers. This instability manifests itself through localized plumelike bursts, perturbing the free liquid surface. Here we present an expanded experimental account regarding the dynamics of individual plumes and the statistics pertaining to the complex collective interaction between plumes, which leads to plume coagulation. We also present a detailed description of an optical technique that enables the visualization and measurement of surface perturbations in coating flows within a rotating horizontal drum.

  17. Adsorption of fluids on solid surfaces: A route toward very dense layers

    NASA Astrophysics Data System (ADS)

    Sartarelli, S. A.; Szybisz, L.

    2012-08-01

    Adsorption of Xe on single planar walls is investigated in the frame of a density functional theory. The strength of the adsorbate-substrate attraction is changed by considering surfaces of Cs, Na, Li, and Mg. The behavior is analyzed by varying the temperature T (between the triple point Tt and the critical Tc) and the coverage Γℓ. The obtained adsorption isotherms exhibit a variety of wetting situations. Density profiles are reported. It is shown that for strongly attractive surfaces the adsorbed liquid becomes very dense reaching densities characteristic of solids.

  18. Experimental and computational studies of sound transmission in a branching airway network embedded in a compliant viscoelastic medium

    NASA Astrophysics Data System (ADS)

    Dai, Zoujun; Peng, Ying; Mansy, Hansen A.; Sandler, Richard H.; Royston, Thomas J.

    2015-03-01

    Breath sounds are often used to aid in the diagnosis of pulmonary disease. Mechanical and numerical models could be used to enhance our understanding of relevant sound transmission phenomena. Sound transmission in an airway mimicking phantom was investigated using a mechanical model with a branching airway network embedded in a compliant viscoelastic medium. The Horsfield self-consistent model for the bronchial tree was adopted to topologically couple the individual airway segments into the branching airway network. The acoustics of the bifurcating airway segments were measured by microphones and calculated analytically. Airway phantom surface motion was measured using scanning laser Doppler vibrometry. Finite element simulations of sound transmission in the airway phantom were performed. Good agreement was achieved between experiments and simulations. The validated computational approach can provide insight into sound transmission simulations in real lungs.

  19. Evaluation of a coupled model for numerical simulation of a multiphase flow system in a porous medium and a surface fluid.

    PubMed

    Hibi, Yoshihiko; Tomigashi, Akira

    2015-09-01

    Numerical simulations that couple flow in a surface fluid with that in a porous medium are useful for examining problems of pollution that involve interactions among atmosphere, water, and groundwater, including saltwater intrusion along coasts. Coupled numerical simulations of such problems must consider both vertical flow between the surface fluid and the porous medium and complicated boundary conditions at their interface. In this study, a numerical simulation method coupling Navier-Stokes equations for surface fluid flow and Darcy equations for flow in a porous medium was developed. Then, the basic ability of the coupled model to reproduce (1) the drawdown of a surface fluid observed in square-pillar experiments, using pillars filled with only fluid or with fluid and a porous medium and (2) the migration of saltwater (salt concentration 0.5%) in the porous medium using the pillar filled with fluid and a porous medium was evaluated. Simulations that assumed slippery walls reproduced well the results with drawdowns of 10-30 cm when the pillars were filled with packed sand, gas, and water. Moreover, in the simulation of saltwater infiltration by the method developed in this study, velocity was precisely reproduced because the experimental salt concentration in the porous medium after saltwater infiltration was similar to that obtained in the simulation. Furthermore, conditions across the boundary between the porous medium and the surface fluid were satisfied in these numerical simulations of square-pillar experiments in which vertical flow predominated. Similarly, the velocity obtained by the simulation for a system coupling flow in surface fluid with that in a porous medium when horizontal flow predominated satisfied the conditions across the boundary. Finally, it was confirmed that the present simulation method was able to simulate a practical-scale surface fluid and porous medium system. All of these numerical simulations, however, required a great deal of

  20. Sustained distribution of aerosolized PEGylated liposomes in epithelial lining fluids on alveolar surfaces.

    PubMed

    Kaneko, Keita; Togami, Kohei; Yamamoto, Eri; Wang, Shujun; Morimoto, Kazuhiro; Itagaki, Shirou; Chono, Sumio

    2016-10-01

    The distribution characteristics of aerosolized PEGylated liposomes in alveolar epithelial lining fluid (ELF) were examined in rats, and the ensuing mechanisms were investigated in the in vitro uptake and protein adsorption experiments. Nonmodified or PEGylated liposomes (particle size 100 nm) were aerosolized into rat lungs. PEGylated liposomes were distributed more sustainably in ELFs than nonmodified liposomes. Furthermore, the uptake of PEGylated liposomes by alveolar macrophages (AMs) was less than that of nonmodified liposomes. In further in vitro uptake experiments, nonmodified and PEGylated liposomes were opsonized with rat ELF components and then added to NR8383 cells as cultured rat AMs. The uptake of opsonized PEGylated liposomes by NR8383 cells was lower than that of opsonized nonmodified liposomes. Moreover, the protein absorption levels in opsonized PEGylated liposomes were lower than those in opsonized nonmodified liposomes. These findings suggest that sustained distributions of aerosolized PEGylated liposomes in ELFs reflect evasion of liposomal opsonization with surfactant proteins and consequent reductions in uptake by AMs. These data indicate the potential of PEGylated liposomes as aerosol-based drug delivery system that target ELF for the treatment of respiratory diseases.

  1. Computational Fluid Dynamics Analysis on Radiation Error of Surface Air Temperature Measurement

    NASA Astrophysics Data System (ADS)

    Yang, Jie; Liu, Qing-Quan; Ding, Ren-Hui

    2017-01-01

    Due to solar radiation effect, current air temperature sensors inside a naturally ventilated radiation shield may produce a measurement error that is 0.8 K or higher. To improve air temperature observation accuracy and correct historical temperature of weather stations, a radiation error correction method is proposed. The correction method is based on a computational fluid dynamics (CFD) method and a genetic algorithm (GA) method. The CFD method is implemented to obtain the radiation error of the naturally ventilated radiation shield under various environmental conditions. Then, a radiation error correction equation is obtained by fitting the CFD results using the GA method. To verify the performance of the correction equation, the naturally ventilated radiation shield and an aspirated temperature measurement platform are characterized in the same environment to conduct the intercomparison. The aspirated temperature measurement platform serves as an air temperature reference. The mean radiation error given by the intercomparison experiments is 0.23 K, and the mean radiation error given by the correction equation is 0.2 K. This radiation error correction method allows the radiation error to be reduced by approximately 87 %. The mean absolute error and the root mean square error between the radiation errors given by the correction equation and the radiation errors given by the experiments are 0.036 K and 0.045 K, respectively.

  2. United airway disease: current perspectives

    PubMed Central

    Giavina-Bianchi, Pedro; Aun, Marcelo Vivolo; Takejima, Priscila; Kalil, Jorge; Agondi, Rosana Câmara

    2016-01-01

    Upper and lower airways are considered a unified morphological and functional unit, and the connection existing between them has been observed for many years, both in health and in disease. There is strong epidemiologic, pathophysiologic, and clinical evidence supporting an integrated view of rhinitis and asthma: united airway disease in the present review. The term “united airway disease” is opportune, because rhinitis and asthma are chronic inflammatory diseases of the upper and lower airways, which can be induced by allergic or nonallergic reproducible mechanisms, and present several phenotypes. Management of rhinitis and asthma must be jointly carried out, leading to better control of both diseases, and the lessons of the Allergic Rhinitis and Its Impact on Asthma initiative cannot be forgotten. PMID:27257389

  3. Extraglottic airway devices: A review

    PubMed Central

    Ramaiah, Ramesh; Das, Debasmita; Bhananker, Sanjay M; Joffe, Aaron M

    2014-01-01

    Extraglottic airway devices (EAD) have become an integral part of anesthetic care since their introduction into clinical practice 25 years ago and have been used safely hundreds of millions of times, worldwide. They are an important first option for difficult ventilation during both in-hospital and out-of-hospital difficult airway management and can be utilized as a conduit for tracheal intubation either blindly or assisted by another technology (fiberoptic endoscopy, lightwand). Thus, the EAD may be the most versatile single airway technique in the airway management toolbox. However, despite their utility, knowledge regarding specific devices and the supporting data for their use is of paramount importance to patient's safety. In this review, number of commercially available EADs are discussed and the reported benefits and potential pitfalls are highlighted. PMID:24741502

  4. Airway epithelial repair, regeneration, and remodeling after injury in chronic obstructive pulmonary disease.

    PubMed

    Puchelle, Edith; Zahm, Jean-Marie; Tournier, Jean-Marie; Coraux, Christelle

    2006-11-01

    In chronic obstructive pulmonary disease (COPD), exacerbations are generally associated with several causes, including pollutants, viruses, bacteria that are responsible for an excess of inflammatory mediators, and proinflammatory cytokines released by activated epithelial and inflammatory cells. The normal response of the airway surface epithelium to injury includes a succession of cellular events, varying from the loss of the surface epithelium integrity to partial shedding of the epithelium or even complete denudation of the basement membrane. The epithelium then has to repair and regenerate to restore its functions, through several mechanisms, including basal cell spreading and migration, followed by proliferation and differentiation of epithelial cells. In COPD, the remodeling of the airway epithelium, such as squamous metaplasia and mucous hyperplasia that occur during injury, may considerably disturb the innate immune functions of the airway epithelium. In vitro and in vivo models of airway epithelial wound repair and regeneration allow the study of the spatiotemporal modulation of cellular and molecular interaction factors-namely, the proinflammatory cytokines, the matrix metalloproteinases and their inhibitors, and the intercellular adhesion molecules. These factors may be markedly altered during exacerbation periods of COPD and their dysregulation may induce remodeling of the airway mucosa and a leakiness of the airway surface epithelium. More knowledge of the mechanisms involved in airway epithelium regeneration may pave the way to cytoprotective and regenerative therapeutics, allowing the reconstitution of a functional, well-differentiated airway epithelium in COPD.

  5. Electroanalytical and surface plasmon resonance sensors for detection of breast cancer and Alzheimer's disease biomarkers in cells and body fluids.

    PubMed

    Yang, Minghui; Yi, Xinyao; Wang, Jianxiu; Zhou, Feimeng

    2014-04-21

    Cancer and neurological disorders are two leading causes of human death. Their early diagnoses will either greatly improve the survival rate or facilitate effective treatments or modalities. Detection of biomarkers in body fluids and some tissues (e.g., blood, urine and cerebrospinal fluids) is relatively non-invasive and provides useful chemical and biological information that is complementary to tomographic imaging (e.g., magnetic resonance imaging, positron emission tomography and X-ray computed tomography). Recent years have witnessed the contributions from and potential applications of bioanalytical methods for early detection of major diseases. In this review, we survey some recent developments of electroanalytical (as a representative label-based technique) and surface plasmon resonance (SPR) (as a representative label-free technique) biosensors for detection of biomarkers relevant to etiologies of breast cancer and Alzheimer's disease (AD). While breast cancer is representative of cancers of complexity (multiple biomarkers, false positives from tomographic scans, and a need for more effective early diagnostic methods), AD is the most prevalent neurological disorder that is also linked to multiple biomarkers. Both electroanalytical and SPR-based sensors have attractive features of sensitivity, portability, obviation of large sample volumes, and capability of multiplexed detection. Various sensing protocols developed in the past five years are reviewed, demonstrating the feasibility of both techniques for diagnostic purposes. Problems inherent in these two techniques that must be overcome before being clinically viable are also discussed.

  6. Surface tension of dilute alcohol-aqueous binary fluids: n-Butanol/water, n-Pentanol/water, and n-Hexanol/water solutions

    NASA Astrophysics Data System (ADS)

    Cheng, Kuok Kong; Park, Chanwoo

    2017-01-01

    Surface tension of pure fluids, inherently decreasing with regard to temperature, creates a thermo-capillary-driven (Marangoni) flow moving away from a hot surface. It has been known that few high-carbon alcohol-aqueous solutions exhibit an opposite behavior of the surface tension increasing with regard to temperature, such that the Marangoni flow moves towards the hot surface (self-rewetting effect). We report the surface tensions of three dilute aqueous solutions of n-Butanol, n-Pentanol and n-Hexanol as self-rewetting fluids measured for ranges of alcohol concentration (within solubility limits) and fluid temperatures (25-85 °C). A maximum bubble pressure method using a leak-tight setup was used to measure the surface tension without evaporation losses of volatile components. It was found from this study that the aqueous solutions with higher-carbon alcohols exhibit a weak self-rewetting behavior, such that the surface tensions remain constant or slightly increases above about 60 °C. These results greatly differ from the previously reported results showing a strong self-rewetting behavior, which is attributed to the measurement errors associated with the evaporation losses of test fluids during open-system experiments.

  7. Imaging of mucus clearance in the airways of living spontaneously breathing mice by optical coherence microscopy (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Pieper, Mario; Schulz-Hildebrandt, Hinnerk; Hüttmann, Gereon; König, Peter

    2016-03-01

    Mucus transport is essential to remove inhaled particles and pathogens from the lung. Impaired removal of mucus often results in worsening of lung diseases. To understand the mechanisms of mucus transport and to monitor the impact of therapeutic strategies, it is essential to visualize airways and mucus in living animals without disturbing transport processes by intubation or surgically opening the airways. We developed a custom-built optical coherence microscope (OCM) providing a lateral and axial resolution of approximately 1.5 µm with a field of view of 2 mm at up to 150 images/s. Images of the intact trachea and its mucus transport were recorded in anesthetized spontaneously breathing mice. NaCl solution (0.9% and 7%) or Lipopolysaccharide were applied intranasally. OCM resolved detailed structure of the trachea and enabled measuring the airway surface liquid (ASL) thickness through the tracheal wall. Without stimulation, the amount of ASL was only a few µm above the epithelium and remained constant. After intranasal application of 30 µl saline at different concentrations, an early fast cough-like fluid removal with velocities higher than 1 mm/s was observed that removed a high amount of liquid. The ASL thickness increased transiently and quickly returned to levels before stimulation. In contrast to saline, application of Lipopolysaccharide induced substantial mucus release and an additional slow mucus transport by ciliary beating (around 100 µm/s) towards the larynx was observed. In conclusion, OCM is appropriate unique tool to study mechanisms of mucus transport in the airways and effects of therapeutic interventions in living animals.

  8. Surface uplift and time-dependent seismic hazard due to fluid-injection in eastern Texas

    NASA Astrophysics Data System (ADS)

    Shirzaei, M.; Ellsworth, W. L.; Tiampo, K. F.; González, P. J.; Manga, M.

    2015-12-01

    US states such as Texas and Oklahoma that produce high-volumes of unconventional oil and gas, are facing a sharp increase in seismicity. Observations of the associated surface deformation and accompanying physical models that unequivocally link the seismicity and waste water injection are scarce. Here, we find that the waste water injection in eastern Texas causes uplift, detectable using radar interferometric data. Combining the uplift and injection data through a poroelastic model allows for the resolution of a complex crustal distribution of hydraulic conductivity and pore pressure. We find that the ~5 years pore pressure increase is capable of triggering the 17 May 2012, Mw 4.8 earthquake, the largest event recorded in east Texas. This study shows that surface deformation data are vital in order to constrain the spatiotemporal variations of the stress field in the vicinity of injection sites.

  9. Characterization of Near Wall Surface Chemistry and Fluid Interaction in Hypersonic Boundary Layers

    DTIC Science & Technology

    2009-03-01

    required to obtain concentration profiles under the isothermal and isobaric conditions of the dead-end side-arm reactor. The ideal gas law was used as the...nitrogen and an NO titration technique to generate different mixtures of O and N atoms. In the first approach, two photon LIF of atomic oxygen and...used together with isotropically labeled titration gases to detect surface produced NO directly at two different positions in the diffusion tube as a

  10. Coupling fluid and solute dynamics within the ocular surface tear film: a modelling study of black line osmolarity.

    PubMed

    Zubkov, V S; Breward, C J W; Gaffney, E A

    2012-09-01

    We present a mathematical model describing the spatial distribution of tear film osmolarity across the ocular surface of a human eye during one blink cycle, incorporating detailed fluid and solute dynamics. Based on the lubrication approximation, our model comprises three coupled equations tracking the depth of the aqueous layer of the tear film, the concentration of the polar lipid, and the concentration of physiological salts contained in the aqueous layer. Diffusive boundary layers in the salt concentration occur at the thinnest regions of the tear film, the black lines. Thus, despite large Peclet numbers, diffusion ameliorates osmolarity around the black lines, but nonetheless is insufficient to eliminate the build-up of solute in these regions. More generally, a heterogeneous distribution of solute concentration is predicted across the ocular surface, indicating that measurements of lower meniscus osmolarity are not globally representative, especially in the presence of dry eye. Vertical saccadic eyelid motion can reduce osmolarity at the lower black line, raising the prospect that select eyeball motions more generally can assist in alleviating tear film hyperosmolarity. Finally, our results indicate that measured evaporative rates will induce excessive hyperosmolarity at the black lines, even for the healthy eye. This suggests that further evaporative retardation at the black lines, for instance due to the cellular glycocalyx at the ocular surface or increasing concentrations of mucus, will be important for controlling hyperosmolarity as the black line thins.

  11. Mechanism of calcium disilicide-induced calcification of crystalline silicon surfaces in simulated body fluid under zero bias.

    PubMed

    Seregin, Vladimir V; Coffer, Jeffery L

    2008-10-01

    A dry-etch spark ablation method was used to produce calcium disilicide (CaSi2/Si) layers on silicon surfaces, and their biomineralization under zero bias was followed by means of scanning electron microscopy, X-ray energy dispersive analysis, and Raman spectroscopy. CaSi2/Si wafers are bioinert at 25 degrees C and bioactive at 37 degrees C. Mechanistic insights regarding biomineralization were derived from an analysis of film growth morphology and chemical composition after various soaking periods in standard simulated body fluid (SBF). Changes in CaSi2/Si calcification behavior as a function of reaction temperature and pH, SBF concentration, and various surface modification processes were also employed for this purpose. During CaSi2/Si calcification under zero bias, calcium phosphate (CaP) growth is strongly dependent on the structural degradation of CaSi2/Si grains. Surface silanol groups, initially present on the as-prepared material, cannot induce CaP nucleation, which begins only upon delamination of CaSi2/Si layers. The calcium phosphate phases, which are present during various growth stages, possibly include a combination of Mg-substituted whitlockite, monetite, and tricalcium phosphate.

  12. Effect of surface tension on the dynamical behavior of bubble in rotating fluids under low gravity environment

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Tsao, Y. D.; Leslie, Fred W.; Hong, B. B.

    1988-01-01

    Time dependent evolutions of the profile of free surface (bubble shapes) for a cylindrical container partially filled with a Newtonian fluid of constant density, rotating about its axis of symmetry, have been studied. Numerical computations of the dynamics of bubble shapes have been carried out with the following situations: (1) linear functions of spin-up and spin-down in low and microgravity environments, (2) linear functions of increasing and decreasing gravity enviroment in high and low rotating cylidner speeds, (3) step functions of spin-up and spin-down in a low gravity environment, and (4) sinusoidal function oscillation of gravity environment in high and low rotating cylinder speeds. The initial condition of bubble profiles was adopted from the steady-state formulations in which the computer algorithms have been developed by Hung and Leslie (1988), and Hung et al. (1988).

  13. Satellite-based measurements of surface deformation reveal fluid flow associated with the geological storage of carbon dioxide

    SciTech Connect

    Vasco, D.W.; Rucci, A.; Ferretti, A.; Novali, F.; Bissell, R.; Ringrose, P.; Mathieson, A.; Wright, I.

    2009-10-15

    Interferometric Synthetic Aperture Radar (InSAR), gathered over the In Salah CO{sub 2} storage project in Algeria, provides an early indication that satellite-based geodetic methods can be effective in monitoring the geological storage of carbon dioxide. An injected volume of 3 million tons of carbon dioxide, from one of the first large-scale carbon sequestration efforts, produces a measurable surface displacement of approximately 5 mm/year. Using geophysical inverse techniques we are able to infer flow within the reservoir layer and within a seismically detected fracture/ fault zone intersecting the reservoir. We find that, if we use the best available elastic Earth model, the fluid flow need only occur in the vicinity of the reservoir layer. However, flow associated with the injection of the carbon dioxide does appear to extend several kilometers laterally within the reservoir, following the fracture/fault zone.

  14. Thixotropic solutions enhance viral-mediated gene transfer to airway epithelia.

    PubMed

    Seiler, Michael P; Luner, Paul; Moninger, Thomas O; Karp, Philip H; Keshavjee, Shaf; Zabner, Joseph

    2002-08-01

    Adenovirus-mediated gene transfer to airway epithelia is inefficient in part because its receptor is absent on the apical surface of the airways. Targeting adenovirus to other receptors, increasing the viral concentration, and even prolonging the incubation time with adenovirus vectors can partially overcome the lack of receptors and facilitate gene transfer. Unfortunately, mucociliary clearance would prevent prolonged incubation time in vivo. Thixotropic solutions (TS) are gels that upon a vigorous shearing force reversibly become liquid. We hypothesized that formulating recombinant adenoviruses in TS would decrease virus clearance and thus enhance gene transfer to the airway epithelia. We found that clearance of virus-sized fluorescent beads by human airway epithelia in vitro and by monkey trachea in vivo were markedly decreased when the beads were formulated in TS compared with phosphate-buffered saline (PBS). Adenovirus formulated in TS significantly increased adenovirus-mediated gene transfer of a reporter gene in human airway epithelia in vitro and in murine airway epithelia in vivo. Furthermore, an adenovirus encoding the cystic fibrosis transmembrane regulator (CFTR) gene (AdCFTR) formulated in TS was more efficient in correcting the chloride transport defect in cystic fibrosis airway epithelia than AdCFTR formulated in PBS. These data indicate a novel strategy to augment the efficiency of gene transfer to the airways that may be applicable to a number of different gene transfer vectors and could be of value in gene transfer to cystic fibrosis (CF) airway epithelia in vivo.

  15. A new removable airway stent

    PubMed Central

    Amundsen, Tore; Sørhaug, Sveinung; Leira, Håkon Olav; Tyvold, Stig Sverre; Langø, Thomas; Hammer, Tommy; Manstad-Hulaas, Frode; Mattsson, Erney

    2016-01-01

    Background Malignant airway obstruction is a feared complication and will most probably occur more frequently in the future because of increasing cancer incidence and increased life expectancy in cancer patients. Minimal invasive treatment using airway stents represents a meaningful and life-saving palliation. We present a new removable airway stent for improved individualised treatment. Methods To our knowledge, the new airway stent is the world's first knitted and uncovered self-expanding metal stent, which can unravel and be completely removed. In an in vivo model using two anaesthetised and spontaneously breathing pigs, we deployed and subsequently removed the stents by unravelling the device. The procedures were executed by flexible bronchoscopy in an acute and a chronic setting – a ‘proof-of-principle’ study. Results The new stent was easily and accurately deployed in the central airways, and it remained fixed in its original position. It was easy to unravel and completely remove from the airways without clinically significant complications. During the presence of the stent in the chronic study, granulation tissue was induced. This tissue disappeared spontaneously with the removal. Conclusions The new removable stent functioned according to its purpose and unravelled easily, and it was completely removed without significant technical or medical complications. Induced granulation tissue disappeared spontaneously. Further studies on animals and humans are needed to define its optimal indications and future use. PMID:27608269

  16. Incorporating and Compensating Cerebrospinal Fluid in Surface-Based Forward Models of Magneto- and Electroencephalography

    PubMed Central

    Stenroos, Matti; Nummenmaa, Aapo

    2016-01-01

    MEG/EEG source imaging is usually done using a three-shell (3-S) or a simpler head model. Such models omit cerebrospinal fluid (CSF) that strongly affects the volume currents. We present a four-compartment (4-C) boundary-element (BEM) model that incorporates the CSF and is computationally efficient and straightforward to build using freely available software. We propose a way for compensating the omission of CSF by decreasing the skull conductivity of the 3-S model, and study the robustness of the 4-C and 3-S models to errors in skull conductivity. We generated dense boundary meshes using MRI datasets and automated SimNIBS pipeline. Then, we built a dense 4-C reference model using Galerkin BEM, and 4-C and 3-S test models using coarser meshes and both Galerkin and collocation BEMs. We compared field topographies of cortical sources, applying various skull conductivities and fitting conductivities that minimized the relative error in 4-C and 3-S models. When the CSF was left out from the EEG model, our compensated, unbiased approach improved the accuracy of the 3-S model considerably compared to the conventional approach, where CSF is neglected without any compensation (mean relative error < 20% vs. > 40%). The error due to the omission of CSF was of the same order in MEG and compensated EEG. EEG has, however, large overall error due to uncertain skull conductivity. Our results show that a realistic 4-C MEG/EEG model can be implemented using standard tools and basic BEM, without excessive workload or computational burden. If the CSF is omitted, compensated skull conductivity should be used in EEG. PMID:27472278

  17. Altered Sputum Microstructure as a Marker of Airway Obstruction in Cystic Fibrosis Patients

    NASA Astrophysics Data System (ADS)

    Duncan, Gregg; Jung, James; West, Natalie; Boyle, Michael; Suk, Jung Soo; Hanes, Justin

    In the lungs of cystic fibrosis (CF) patients, highly viscoelastic mucus remains stagnant in the lung leading to obstructed airways prone to recurrent infections. Bulk-fluid rheological measurement is primarily used to assess the pathological features of mucus. However, this approach is limited in detecting microscopic properties on the length scale of pathogens and immune cells. We have shown in prior work based on the transport of muco-inert nanoparticles (MIP) in CF sputum that patients can carry significantly different microstructural properties. In this study, we aimed to determine the factors leading to variations between patients in sputum microstructure and their clinical implications. The microrheological properties of CF sputum were measured using multi-particle tracking experiments of MIP. MIP were made by grafting polyethylene glycol onto the surface of polystyrene nanoparticles which prior work has shown prevents adhesion to CF sputum. Biochemical analyses show that sputum microstructure was significantly altered by elevated mucin and DNA content. Reduction in sputum pore size is characteristic of patients with obstructed airways as indicated by measured pulmonary function tests. Our microstructural read-out may serve as a novel biomarker for CF.

  18. Response Surface Modeling of Combined-Cycle Propulsion Components using Computational Fluid Dynamics

    NASA Technical Reports Server (NTRS)

    Steffen, C. J., Jr.

    2002-01-01

    Three examples of response surface modeling with CFD are presented for combined cycle propulsion components. The examples include a mixed-compression-inlet during hypersonic flight, a hydrogen-fueled scramjet combustor during hypersonic flight, and a ducted-rocket nozzle during all-rocket flight. Three different experimental strategies were examined, including full factorial, fractionated central-composite, and D-optimal with embedded Plackett-Burman designs. The response variables have been confined to integral data extracted from multidimensional CFD results. Careful attention to uncertainty assessment and modeling bias has been addressed. The importance of automating experimental setup and effectively communicating statistical results are emphasized.

  19. Fluid surface behavior in low gravity. Center discretionary fund no. 83-21

    NASA Technical Reports Server (NTRS)

    Leslie, F.; Gans, R. F.; Schafer, C.

    1985-01-01

    Measurements of rotating equilibrium bubble shapes in the low-gravity environment of a free-falling aircraft are presented. Emphasis is placed on bubbles which intersect the container boundaries. These data are compared with theoretical profiles derived from Laplace's formula and are in good agreement with the measurements. Two types of instability are explored. The first occurs when the baffle spacing is too large for the bubble to intersect both the top and bottom boundaries. The second occurs when the hydrostatic pressure beneath a displaced free surface does not compensate for pressure change due to capillary forces. The interface shape depends on the contact angle, the radius of intersection with container, and the parameter F which is a measure of the relative importance of centrifugal force to surface tension. For isolated bubbles, F has a maximum value of 1/2. A further increase in F causes the bubble to break contact with the axis of rotation. For large values of F, the bubble becomes more cylindrical and the capillary rise occurs over a thinner layer so that the small radius of curvature can generate enough pressure drop to balance the increased hydrostatic contribution.

  20. Fluoride-containing bioactive glasses: surface reactivity in simulated body fluids solutions.

    PubMed

    Lusvardi, G; Malavasi, G; Menabue, L; Aina, V; Morterra, C

    2009-11-01

    The issue of the contribution of the addition of F to glass bioactivity is not well resolved. This work reports on the surface reactivity in different solutions (DMEM and Tris) for some potentially bioactive glasses based on the composition of 45S5 glass, in which CaF(2) is substituted alternately for (part of) CaO and Na(2)O. The reactivity of F-containing glasses has been compared with that of the reference 45S5 system. The aim of this study is to explain in detail the mechanism of formation of an apatitic crystalline phase at the interface between the inorganic material and simulated biological media. A multi-technique investigation approach proposes a set of reactions involving Ca-carbonate formation, which are somewhat different from that formerly proposed by Hench for 45S5 bioactive glass, and which occur when a F-containing glass surface is in contact with a SBF. The usefulness of IR spectroscopy in recognizing the starting step of apatite (and/or FA) formation with respect to XRD technique is well established here.

  1. Fluid imbalance

    MedlinePlus

    ... up in the body. This is called fluid overload (volume overload). This can lead to edema (excess fluid in ... Water imbalance; Fluid imbalance - dehydration; Fluid buildup; Fluid overload; Volume overload; Loss of fluids; Edema - fluid imbalance; ...

  2. Airway Hydration and COPD

    PubMed Central

    Ghosh, Arunava; Boucher, R.C.; Tarran, Robert

    2015-01-01

    Chronic obstructive pulmonary disease (COPD) is one of the prevalent causes of worldwide mortality and encompasses two major clinical phenotypes, i.e., chronic bronchitis (CB) and emphysema. The most common cause of COPD is chronic tobacco inhalation. Research focused on the chronic bronchitic phenotype of COPD has identified several pathological processes that drive disease initiation and progression. For example, the lung’s mucociliary clearance (MCC) system performs the critical task of clearing inhaled pathogens and toxic materials from the lung. MCC efficiency is dependent on: (i) the ability of apical plasma membrane ion channels such as the cystic fibrosis transmembrane conductance regulator (CFTR) and the epithelial Na+ channel (ENaC) to maintain airway hydration; (ii) ciliary beating; and, (iii) appropriate rates of mucin secretion. Each of these components is impaired in CB and likely contributes to the mucus stasis/accumulation seen in CB patients. This review highlights the cellular components responsible for maintaining MCC and how this process is disrupted following tobacco exposure and with CB. We shall also discuss existing therapeutic strategies for the treatment of chronic bronchitis and how components of the MCC can be used as biomarkers for the evaluation of tobacco or tobacco-like-product exposure. PMID:26068443

  3. Liquid Therapy Delivery Models Using Microfluidic Airways

    NASA Astrophysics Data System (ADS)

    Mulligan, Molly K.; Grotberg, James B.; Waisman, Dan; Filoche, Marcel; Sznitman, Josué

    2013-11-01

    The propagation and break-up of viscous and surfactant-laden liquid plugs in the lungs is an active area of research in view of liquid plug installation in the lungs to treat a host of different pulmonary conditions. This includes Infant Respiratory Distress Syndrome (IRDS) the primary cause of neonatal death and disability. Until present, experimental studies of liquid plugs have generally been restricted to low-viscosity Newtonian fluids along a single bifurcation. However, these fluids reflect poorly the actual liquid medication therapies used to treat pulmonary conditions. The present work attempts to uncover the propagation, rupture and break-up of liquid plugs in the airway tree using microfluidic models spanning three or more generations of the bronchiole tree. Our approach allows the dynamics of plug propagation and break-up to be studied in real-time, in a one-to-one scale in vitro model, as a function of fluid rheology, trailing film dynamics and bronchial tree geometry. Understanding these dynamics are a first and necessary step to deliver more effectively boluses of liquid medication to the lungs while minimizing the injury caused to epithelial cells lining the lungs from the rupture of such liquid plugs.

  4. Characterization of reservoir rocks and fluids by surface electromagnetic transient methods

    SciTech Connect

    Hoekstra, P.; Blohm, M.W.; Stoyer, C.H.; James, B.A.

    1992-07-17

    The objectives of this research were to improve the interpretations of transient electromagnetic (TEM) measurements over two-dimensional subsurface structures. TEM is a surface electromagnetic method employed in fossil energy reservoir exploration and characterization. Electrical measurements find application in (i) assisting in fossil energy exploration mainly in areas where seismic methods yield inadequate data quality, such as volcanic covered terrain, permafrost areas, and the Rocky Mountain Overthrust; (ii) mapping contacts between hydrocarbon and brines in shallow producing horizon, and (iii) in monitoring enhanced oil recovery processes which cause zones of lower resistivity. The work under this contract consisted of three tasks: (1) Selection of a test site and acquisition of a high density, 3-component data set over the test site; (2) development of finite element modeling algorithms for computing 3-D EM fields over 2-D EM fields over 2-D subsurface structures; and development of TEM 2-D subsurface imaging method. Accomplishments for this period are described.

  5. Heat transfer and fluid mechanics measurements in transitional boundary layers on convex-curved surfaces

    NASA Technical Reports Server (NTRS)

    Wang, T.; Simon, T. W.

    1987-01-01

    The test section of the present experiment to ascertain the effects of convex curvature and freestream turbulence on boundary layer momentum and heat transfer during natural transition provided a two-dimensional boundary layer flow on a uniformly heated curved surface, with bending to various curvature radii, R. Attention is given to results for the cases of R = infinity, 180 cm, and 90 cm, each with two freestream turbulence intensity levels. While the mild convex curvature of R = 180 cm delays transition, further bending to R = 90 cm leads to no signifucant further delay of transition. Cases with both curvature and higher freestream disturbance effects exhibit the latter's pronounced dominance. These data are pertinent to the development of transition prediction models for gas turbine blade design.

  6. Fluids in Contact with a Hard Surface: Universality of the Bridge Functions for the Density Profile.

    DTIC Science & Technology

    1986-05-27

    partial DD 4A~ 1473 gOriI oF INov es iOs sorre Unclassified / 01 02.LP.01 4.66 01 SECUFNITY ct.ASSIVICATION or THIS% Pikee (EI.. t e.#I* l~~~~~ ~- INC .I IV...I I"II I.. . + -I >- . UNCLASSIFIED sZCUPM"T C7- -t’ FICAT1000 OF THIS PACZ(W- D~IA vt. Abstract (Cont.) derivative of the free energy with respect...WITH A HARD SURFACE: UNIVERSALITY OF THE BRIDGE FUNCTIONS FOR THE DENSITY PROFILE by Y. Rosenfeld Nuclear Research Centre-Negev. P.O. Box 9901 Beer-Sheva

  7. Efficacy of Surgical Airway Plasty for Benign Airway Stenosis

    PubMed Central

    Takahama, Makoto; Nakajima, Ryu; Kimura, Michitaka; Inoue, Hidetoshi; Yamamoto, Ryoji

    2015-01-01

    Background: Long-term patency is required during treatment for benign airway stenosis. This study investigated the effectiveness of surgical airway plasty for benign airway stenosis. Methods: Clinical courses of 20 patients, who were treated with surgical plasty for their benign airway stenosis, were retrospectively investigated. Results: Causes of stenosis were tracheobronchial tuberculosis in 12 patients, post-intubation stenosis in five patients, malacia in two patients, and others in one patient. 28 interventional pulmonology procedures and 20 surgical plasty were performed. Five patients with post-intubation stenosis and four patients with tuberculous stenosis were treated with tracheoplasty. Eight patients with tuberculous stenosis were treated with bronchoplasty, and two patients with malacia were treated with stabilization of the membranous portion. Anastomotic stenosis was observed in four patients, and one to four additional treatments were required. Performance status, Hugh–Jones classification, and ventilatory functions were improved after surgical plasty. Outcomes were fair in patients with tuberculous stenosis and malacia. However, efficacy of surgical plasty for post-intubation stenosis was not observed. Conclusion: Surgical airway plasty may be an acceptable treatment for tuberculous stenosis. Patients with malacia recover well after surgical plasty. There may be untreated patients with malacia who have the potential to benefit from surgical plasty. PMID:26567879

  8. Computational Fluid Dynamics Modeling of Bacillus anthracis ...

    EPA Pesticide Factsheets

    Journal Article Three-dimensional computational fluid dynamics and Lagrangian particle deposition models were developed to compare the deposition of aerosolized Bacillus anthracis spores in the respiratory airways of a human with that of the rabbit, a species commonly used in the study of anthrax disease. The respiratory airway geometries for each species were derived from computed tomography (CT) or µCT images. Both models encompassed airways that extended from the external nose to the lung with a total of 272 outlets in the human model and 2878 outlets in the rabbit model. All simulations of spore deposition were conducted under transient, inhalation-exhalation breathing conditions using average species-specific minute volumes. Four different exposure scenarios were modeled in the rabbit based upon experimental inhalation studies. For comparison, human simulations were conducted at the highest exposure concentration used during the rabbit experimental exposures. Results demonstrated that regional spore deposition patterns were sensitive to airway geometry and ventilation profiles. Despite the complex airway geometries in the rabbit nose, higher spore deposition efficiency was predicted in the upper conducting airways of the human at the same air concentration of anthrax spores. This greater deposition of spores in the upper airways in the human resulted in lower penetration and deposition in the tracheobronchial airways and the deep lung than that predict

  9. Airway management in emergency situations.

    PubMed

    Dörges, Volker

    2005-12-01

    Securing and monitoring the airway are among the key requirements of appropriate therapy in emergency patients. Failures to secure the airways can drastically increase morbidity and mortality of patients within a very short time. Therefore, the entire range of measures needed to secure the airway in an emergency, without intermediate ventilation and oxygenation, is limited to 30-40 seconds. Endotracheal intubation is often called the 'gold standard' for airway management in an emergency, but multiple failed intubation attempts do not result in maintaining oxygenation; instead, they endanger the patient by prolonging hypoxia and causing additional trauma to the upper airways. Thus, knowledge and availability of alternative procedures are also essential in every emergency setting. Given the great variety of techniques available, it is important to establish a well-planned, methodical protocol within the framework of an algorithm. This not only facilitates the preparation of equipment and the training of personnel, it also ensures efficient decision-making under time pressure. Most anaesthesia-related deaths are due to hypoxaemia when difficulty in securing the airway is encountered, especially in obstetrics during induction of anaesthesia for caesarean delivery. The most commonly occurring adverse respiratory events are failure to intubate, failure to recognize oesophageal intubation, and failure to ventilate. Thus, it is essential that every anaesthesiologist working on the labour and delivery ward is comfortable with the algorithm for the management of failed intubation. The algorithm for emergency airway management describing the sequence of various procedures has to be adapted to internal standards and to techniques that are available.

  10. Antimicrobial Peptide P60.4Ac-Containing Creams and Gel for Eradication of Methicillin-Resistant Staphylococcus aureus from Cultured Skin and Airway Epithelial Surfaces

    PubMed Central

    Haisma, Elisabeth M.; Göblyös, Anikó; Ravensbergen, Bep; Adriaans, Alwin E.; Cordfunke, Robert A.; Schrumpf, Jasmijn; Limpens, Ronald W. A. L.; Schimmel, Kirsten J. M.; den Hartigh, Jan; Hiemstra, Pieter S.; Drijfhout, Jan Wouter; El Ghalbzouri, Abdoelwaheb

    2016-01-01

    We previously found the LL-37-derived peptide P60.4Ac to be effective against methicillin-resistant Staphylococcus aureus (MRSA) on human epidermal models (EMs). The goal of this study was to identify the preferred carrier for this peptide for topical application on skin and mucosal surfaces. We prepared P60.4Ac in three formulations, i.e., a water-in-oil cream with lanolin (Softisan 649), an oil-in-water cream with polyethylene glycol hexadecyl ether (Cetomacrogol), and a hydroxypropyl methylcellulose (hypromellose) 4000 gel. We tested the antimicrobial efficacy of the peptide in these formulations against mupirocin-resistant and -sensitive MRSA strains on EMs and bronchial epithelial models (BEMs). The cytotoxic effects of formulated P60.4Ac on these models were determined using histology and WST-1 and lactate dehydrogenase assays. Moreover, we assessed the stability of the peptide in these formulations with storage for up to 3 months. Killing of MRSA by P60.4Ac in the two creams was less effective than that by P60.4Ac in the hypromellose gel. In agreement with those findings, P60.4Ac in the hypromellose gel was highly effective in eradicating the two MRSA strains from EMs. We found that even 0.1% (wt/wt) P60.4Ac in the hypromellose gel killed >99% of the viable planktonic bacteria and >85% of the biofilm-associated bacteria on EMs. Hypromellose gels containing 0.1% and 0.5% (wt/wt) P60.4Ac effectively reduced the numbers of viable MRSA cells from BEMs by >90%. No cytotoxic effects of P60.4Ac in the hypromellose gel with up to 2% (wt/wt) P60.4Ac on keratinocytes in EMs and in the hypromellose gel with up to 0.5% (wt/wt) P60.4Ac on epithelial cells in BEMs were observed. High-performance liquid chromatography analysis showed that P60.4Ac was stable in the Softisan cream and the hypromellose gel but not in the Cetomacrogol cream. We conclude that P60.4Ac formulated in hypromellose gel is both stable and highly effective in eradicating MRSA from colonized EMs and

  11. Exact Solution to Stationary Onset of Convection Due to Surface Tension Variation in a Multicomponent Fluid Layer With Interfacial Deformation

    NASA Technical Reports Server (NTRS)

    Skarda, J. Raymond Lee; McCaughan, Frances E.

    1998-01-01

    Stationary onset of convection due to surface tension variation in an unbounded multicomponent fluid layer is considered. Surface deformation is included and general flux boundary conditions are imposed on the stratifying agencies (temperature/composition) disturbance equations. Exact solutions are obtained to the general N-component problem for both finite and infinitesimal wavenumbers. Long wavelength instability may coexist with a finite wavelength instability for certain sets of parameter values, often referred to as frontier points. For an impermeable/insulated upper boundary and a permeable/conductive lower boundary, frontier boundaries are computed in the space of Bond number, Bo, versus Crispation number, Cr, over the range 5 x 10(exp -7) less than or equal to Bo less than or equal to 1. The loci of frontier points in (Bo, Cr) space for different values of N, diffusivity ratios, and, Marangoni numbers, collapsed to a single curve in (Bo, D(dimensional variable)Cr) space, where D(dimensional variable) is a Marangoni number weighted diffusivity ratio.

  12. Pathogenic Yersinia Promotes Its Survival by Creating an Acidic Fluid-Accessible Compartment on the Macrophage Surface

    PubMed Central

    Bahnan, Wael; Boettner, Douglas R.; Westermark, Linda; Fällman, Maria; Schesser, Kurt

    2015-01-01

    Microbial pathogens and host immune cells each initiate events following their interaction in an attempt to drive the outcome to their respective advantage. Here we show that the bacterial pathogen Yersinia pseudotuberculosis sustains itself on the surface of a macrophage by forming acidic fluid-accessible compartments that are partially bounded by the host cell plasma membrane. These Yersinia-containing acidic compartments (YACs) are bereft of the early endosomal marker EEA1 and the lysosomal antigen LAMP1 and readily form on primary macrophages as well as macrophage-like cell lines. YAC formation requires the presence of the Yersinia virulence plasmid which encodes a type III secretion system. Unexpectedly, we found that the initial formation of YACs did not require translocation of the type III effectors into the host cell cytosol; however, the duration of YACs was markedly greater in infections using translocation-competent Y. pseudotuberculosis strains as well as strains expressing the effector YopJ. Furthermore, it was in this translocation- and YopJ-dependent phase of infection that the acidic environment was critical for Y. pseudotuberculosis survival during its interaction with macrophages. Our findings indicate that during its extracellular phase of infection Y. pseudotuberculosis initiates and then, by a separate mechanism, stabilizes the formation of a highly intricate structure on the surface of the macrophage that is disengaged from the endocytic pathway. PMID:26275291

  13. On the biodegradation performance of an Mg-Y-RE alloy with various surface conditions in simulated body fluid.

    PubMed

    Hänzi, Anja C; Gunde, Petra; Schinhammer, Michael; Uggowitzer, Peter J

    2009-01-01

    This study documents the influence of different surface conditions produced by various heat treatments on the in vitro degradation performance of an Mg-Y-RE alloy (WE43) investigated by immersion in simulated body fluid. WE43 samples were, respectively (i) annealed at 525 degrees C (plus artificial aging at 250 degrees C in one case) and afterwards polished; and (ii) polished, annealed at 500 degrees C in air and subsequently investigated in the oxidized state. Thermogravimetric analysis (TGA) indicates a mass gain during oxidation in air, following a square-root law over time. X-ray diffraction spectra imply a growing Y(2)O(3) layer upon oxidation, and Auger electron spectroscopy depth profiles show an increased oxide layer thickness which develops according to the behavior observed by TGA. Macroscopically, the degradation performance of the differently heat-treated samples can be divided into two groups. Annealed and polished samples show a fast and homogeneous degradation which slows with time. Their degradation behavior is approximated by a parabolic law. Oxidized samples exhibit a slow initial degradation rate which increases when the protection of the oxide layer is reduced. Overall, they reveal a sigmoidal degradation behavior. Here the differing degradation performances of the annealed-polished and the oxidized samples are related to the different surface conditions and explained on the basis of a depletion hypothesis.

  14. On using the levelling of the free surface of a Newtonian fluid to measure viscosity and Navier slip length

    PubMed Central

    Gilormini, P.; Teyssèdre, H.

    2013-01-01

    Measuring the relaxation time involved in the levelling of a free surface of a Newtonian fluid laid on a substrate can give access to material parameters. It is shown here how most favourable pattern geometries of the free surface and film thicknesses can be defined for the measures of viscosity and Navier slip length at the fluid–solid interface, respectively. Moreover, we put special emphasis on the conditions required to avoid shear thinning by controlling the maximum shear rate. For initially sinusoidal patterns with infinitesimal amplitudes, an analytical solution including slip at the fluid–solid interface is used, and numerical simulations based on the natural element method allow one to discuss the effect of finite amplitudes. This leads to the definition of a relevance domain for the analytical solution that avoids the need for numerical simulations in practical applications. It is also shown how these results can be applied to crenelated profiles, where Fourier series expansion can be used, but with caution. PMID:24353474

  15. The effect of some fluids on surface oxidation and amount of released iron of stainless steel endodontic files.

    PubMed

    Saghiri, Mohammad Ali; García-Godoy, Franklin; Lotfi, Mehrdad; Mehrvazfar, Peyman; Aminsobhani, Mohsen; Rezaie, Samad; Asgar, Kamal

    2012-01-01

    Endodontic files come in contact with blood, infected pulp tissue, and irrigating solutions during root canal therapy. Some instruments such as stereomicroscopy and scanning electron microscopy are used to observe corrosion of endodontic files which are complicated and dependent on preparation methods. Having knowledge of the corrosion and ion release of endodontic files can help in drawing firm deductions as to which files would perform better in the clinical scenario. Therefore, we have used energy dispersive X-ray analysis and an atomic absorption spectrophotometer to track oxygen on the surface and iron in the exposed media to observe the oxidative rate of the media. In this study, corrosion by blood was higher than other biological fluids, but less than with sodium hypochlorite (NaOCl). Observations of energy dispersive X-ray analysis and atomic absorption spectrophotometer results demonstrated that after exposure the amount of oxygen on the surface and surrounding areas increased. Therefore, the files should be rinsed as soon as possible during and after use to hinder the oxidation rate, but blood may produce a different behavior and it might be considered as a decreased risk of broken stainless steel files remaining in the root canal after treatment.

  16. Response surface methodology applied to Supercritical Fluid Extraction (SFE) of carotenoids from Persimmon (Diospyros kaki L.).

    PubMed

    Zaghdoudi, Khalil; Framboisier, Xavier; Frochot, Céline; Vanderesse, Régis; Barth, Danielle; Kalthoum-Cherif, Jamila; Blanchard, Fabrice; Guiavarc'h, Yann

    2016-10-01

    Supercritical carbon dioxide with ethanol as co-solvent was used to extract carotenoids from persimmon fruits (Diospyros kaki L.). Based on a response surface methodology (RSM), a predicting model describing the effects of CO2 temperature, pressure, flow rate, ethanol percentage and extraction time was set up for each of the four carotenoids of interest. The best extraction yields in our experimental domain were found at 300 bars, 60°C, 25% (w/w) ethanol, 3mL/min flow rate and 30min for xanthophylls (all-trans-lutein, all-trans-zeaxanthin and all-trans-β-cryptoxanthin). The yields were 15.46±0.56, 16.81±1.74 and 33.23±2.91μg/g of persimmon powder for all-trans-lutein, all-trans-zeaxanthin and all-trans-β-cryptoxanthin, respectively. As a non-oxygenated carotenoid, all-trans-β-carotene was better extracted using 100 bars, 40°C, 25% (w/w) ethanol, 1mL/min flow rate and 30min extraction time, with an extraction yield of 11.19±0.47μg/g of persimmon powder.

  17. Distal airway dysfunction identifies pulmonary inflammation in asymptomatic smokers

    PubMed Central

    Berger, Kenneth I.; Pradhan, Deepak R.; Goldring, Roberta M.; Oppenheimer, Beno W.; Rom, William N.

    2016-01-01

    Smoking induced inflammation leads to distal airway destruction. However, the relationship between distal airway dysfunction and inflammation remains unclear, particularly in smokers prior to the development of airway obstruction. Seven normal controls and 16 smokers without chronic obstructive pulmonary disease (COPD) were studied. Respiratory function was assessed using the forced oscillation technique (FOT). Abnormal FOT was defined as elevated resistance at 5 Hz (R5). Parameters reflecting distal lung function included frequency dependence of resistance (R5–20) and dynamic elastance (X5). Inflammation was quantified in concentrated bronchoalveolar lavage utilising cell count differential and cytokines expressed as concentration per mL epithelial lining fluid. All control subjects and seven smokers had normal R5. Nine smokers had elevated R5 with abnormal R5–20 and X5, indicating distal lung dysfunction. The presence of abnormal FOT was associated with two-fold higher lymphocyte and neutrophil counts (p<0.025) and with higher interleukin (IL)-8, eotaxin and fractalkine levels (p<0.01). Reactivity of R5–20 and X5 correlated with levels of IL-8, eotaxin, fractalkine, IL-12p70 and transforming growth factor-α (r>0.47, p<0.01). Distal airway dysfunction in smokers without COPD identifies the presence of distal lung inflammation that parallel reported observations in established COPD. These findings were not evident on routine pulmonary function testing and may allow the identification of smokers at risk of progression to COPD. PMID:27995132

  18. Chloride and potassium channels in cystic fibrosis airway epithelia

    NASA Astrophysics Data System (ADS)

    Welsh, Michael J.; Liedtke, Carole M.

    1986-07-01

    Cystic fibrosis, the most common lethal genetic disease in Caucasians, is characterized by a decreased permeability in sweat gland duct and airway epithelia. In sweat duct epithelium, a decreased Cl- permeability accounts for the abnormally increased salt content of sweat1. In airway epithelia a decreased Cl- permeability, and possibly increased sodium absorption, may account for the abnormal respiratory tract fluid2,3. The Cl- impermeability has been localized to the apical membrane of cystic fibrosis airway epithelial cells4. The finding that hormonally regulated Cl- channels make the apical membrane Cl- permeable in normal airway epithelial cells5 suggested abnormal Cl- channel function in cystic fibrosis. Here we report that excised, cell-free patches of membrane from cystic fibrosis epithelial cells contain Cl- channels that have the same conductive properties as Cl- channels from normal cells. However, Cl- channels from cystic fibrosis cells did not open when they were attached to the cell. These findings suggest defective regulation of Cl- channels in cystic fibrosis epithelia; to begin to address this issue, we performed two studies. First, we found that isoprenaline, which stimulates Cl- secretion, increases cellular levels of cyclic AMP in a similar manner in cystic fibrosis and non-cystic fibrosis epithelial cells. Second, we show that adrenergic agonists open calcium-activated potassium channels, indirectly suggesting that calcium-dependent stimulus-response coupling is intact in cystic fibrosis. These data suggest defective regulation of Cl- channels at a site distal to cAMP accumulation.

  19. Distal airway dysfunction identifies pulmonary inflammation in asymptomatic smokers.

    PubMed

    Berger, Kenneth I; Pradhan, Deepak R; Goldring, Roberta M; Oppenheimer, Beno W; Rom, William N; Segal, Leopoldo N

    2016-10-01

    Smoking induced inflammation leads to distal airway destruction. However, the relationship between distal airway dysfunction and inflammation remains unclear, particularly in smokers prior to the development of airway obstruction. Seven normal controls and 16 smokers without chronic obstructive pulmonary disease (COPD) were studied. Respiratory function was assessed using the forced oscillation technique (FOT). Abnormal FOT was defined as elevated resistance at 5 Hz (R5). Parameters reflecting distal lung function included frequency dependence of resistance (R5-20) and dynamic elastance (X5). Inflammation was quantified in concentrated bronchoalveolar lavage utilising cell count differential and cytokines expressed as concentration per mL epithelial lining fluid. All control subjects and seven smokers had normal R5. Nine smokers had elevated R5 with abnormal R5-20 and X5, indicating distal lung dysfunction. The presence of abnormal FOT was associated with two-fold higher lymphocyte and neutrophil counts (p<0.025) and with higher interleukin (IL)-8, eotaxin and fractalkine levels (p<0.01). Reactivity of R5-20 and X5 correlated with levels of IL-8, eotaxin, fractalkine, IL-12p70 and transforming growth factor-α (r>0.47, p<0.01). Distal airway dysfunction in smokers without COPD identifies the presence of distal lung inflammation that parallel reported observations in established COPD. These findings were not evident on routine pulmonary function testing and may allow the identification of smokers at risk of progression to COPD.

  20. On locating the obstruction in the human upper airway

    NASA Astrophysics Data System (ADS)

    Wang, Yong; Elghobashi, S.

    2013-11-01

    The fluid dynamical properties of the air flow in the human upper airway (UA) are not fully understood at present due to the three-dimensional, patient-specific complex geometry of the airway, flow transition from laminar to turbulent and flow-structure interaction during the breathing cycle. One of the major challenges to surgeons is determining the location of the UA obstruction before performing corrective surgeries. It is quite difficult at present to experimentally measure the instantaneous velocity and pressure at specific points in the human airway. On the other hand, direct numerical simulation (DNS) can predict all the flow properties and resolve all its relevant length- and time-scales. We developed a DNS solver with lattice Boltzmann method (LBM), and used it to investigate the flow in two patient-specific UAs reconstructed from CT scan data. Inspiration and expiration flows through these two airways are studied and compared. Pressure gradient-time signals at different locations in the UAs are used to determine the location of the obstruction. This work was supported by the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health (NIH).

  1. Micro-topography and reactivity of implant surfaces: an in vitro study in simulated body fluid (SBF).

    PubMed

    Gandolfi, M G; Taddei, P; Siboni, F; Perrotti, V; Iezzi, G; Piattelli, A; Prati, C

    2015-02-01

    The creation of micro-textured dental implant surfaces possessing a stimulating activity represents a challenge in implant dentistry; particularly, the formation of a thin, biologically active, calcium-phosphate layer on their surface could help to strengthen the bond to the surrounding bone. The aim of the present study was to characterize in terms of macrostructure, micro-topography and reactivity in simulated body fluid (SBF), the surface of titanium (Ti) implants blasted with TiO2 particles, acid etched with hydrofluoric acid, and activated with Ca and Mg-containing nanoparticles. Sandblasted and acid-etched implants were analyzed by ESEM-EDX (environmental scanning electron microscope with energy dispersive X-ray system) to study the micromorphology of the surface and to perform elemental X-ray microanalysis (microchemical analyses) and element mapping. ESEM-EDX analyses were performed at time 0 and after a 28-day soaking period in SBF Hank's balanced salt solution (HBSS) following ISO 23317 (implants for surgery—in vitro evaluation for apatite-forming ability of implant materials). Microchemical analyses (weight % and atomic %) and element mapping were carried out to evaluate the relative element content, element distribution, and calcium/phosphorus (Ca/P) atomic ratio. Raman spectroscopy was used to assess the possible presence of impurities due to manufacturing and to investigate the phases formed upon HBSS soaking. Micro-morphological analyses showed a micro-textured, highly rough surface with microgrooves. Microchemical analyses showed compositional differences among the apical, middle, and distal thirds. The micro-Raman analyses of the as-received implant showed the presence of amorphous Ti oxide and traces of anatase, calcite, and a carbonaceous material derived from the decomposition of an organic component of lipidic nature (presumably used as lubricant). A uniform layer of Ca-poor calcium phosphates (CaPs) (Ca/P ratio <1.47) was observed after

  2. Airway epithelial control of Pseudomonas aeruginosa infection in cystic fibrosis

    PubMed Central

    Campόdonico, Victoria L; Gadjeva, Mihaela; Paradis-Bleau, Catherine; Uluer, Ahmet; Pier, Gerald B

    2013-01-01

    Defective expression or function of the cystic fibrosis transmembrane conductance regulator (CFTR) underlies the hypersusceptibility of cystic fibrosis (CF) patients to chronic airway infections, particularly with Pseudomonas aeruginosa. CFTR is involved in the specific recognition of P. aeruginosa, thereby contributing to effective innate immunity and proper hydration of the airway surface layer (ASL). In CF, the airway epithelium fails to initiate an appropriate innate immune response, allowing the microbe to bind to mucus plugs that are then not properly cleared because of the dehydrated ASL. Recent studies have identified numerous CFTR-dependent factors that are recruited to the epithelial plasma membrane in response to infection and that are needed for bacterial clearance, a process that is defective in CF patients hypersusceptible to infection with this organism. PMID:18262467

  3. Re-thinking the Laramide: Investigating the role of fluids in producing surface uplift using xenolith mineralogy and geochronology

    NASA Astrophysics Data System (ADS)

    Butcher, Lesley Ann

    associated with phase changes at depth. The results of this study substantiate the hypothesis that chemical alteration of lower continental crust by slab-derived fluids played a role in producing Laramide-related surface uplift of the Colorado Plateau and establishes chemical modification of continental lithosphere as a credible possibility for producing elevated regional topography in continental interiors.

  4. Detonation Nanodiamond Toxicity in Human Airway Epithelial Cells Is Modulated by Air Oxidation

    EPA Science Inventory

    Detonational nanodiamonds (DND), a nanomaterial with an increasing range of industrial and biomedical applications, have previously been shown to induce a pro-inflammatory response in cultured human airway epithelial cells (HAEC). We now show that surface modifications induced by...

  5. Colonization of CF patients' upper airways with S. aureus contributes more decisively to upper airway inflammation than P. aeruginosa.

    PubMed

    Janhsen, Wibke Katharina; Arnold, Christin; Hentschel, Julia; Lehmann, Thomas; Pfister, Wolfgang; Baier, Michael; Böer, Klas; Hünniger, Kerstin; Kurzai, Oliver; Hipler, Uta-Christina; Mainz, Jochen Georg

    2016-10-01

    In cystic fibrosis (CF) patients' airways, inflammatory processes decisively contribute to remodeling and pulmonary destruction. The aims of this study were to compare upper airway (UAW) inflammation in the context of Staphylococcus aureus and Pseudomonas aeruginosa colonization in a longitudinal setting, and to examine further factors influencing UAW inflammation. Therefore, we analyzed soluble inflammatory mediators in noninvasively obtained nasal lavage (NL) of CF patients together with microbiology, medication, and relevant clinical parameters. NL, applying 10 mL of isotonic saline per nostril, was serially performed in 74 CF patients (326 samples). Concentrations of the inflammatory mediators' interleukin (IL)-1β, IL-6, IL-8, matrix metalloproteinase (MMP)-9, and its anti-protease TIMP-1 were quantified by bead-based multiplexed assay, neutrophil elastase (NE) via ELISA. Culture-based microbiology of the upper and lower airways (LAW), as well as serological and clinical findings, were compiled. Our results indicate that UAW colonization with S. aureus significantly impacts the concentration of all measured inflammatory mediators in NL fluid except TIMP-1, whereas these effects were not significant for P. aeruginosa. Patients with S. aureus colonization of both the UAW and LAW showed significantly increased concentrations of IL-1β, IL-6, IL-8, MMP-9, and slightly elevated concentrations of NE in NL fluid compared to non-colonized patients. This work elaborates a survey on S. aureus' virulence factors that may contribute to this underestimated pathology. Serial assessment of epithelial lining fluid by NL reveals that colonization of the UAW with S. aureus contributes more to CF airway inflammatory processes than hitherto expected.

  6. Cystic Fibrosis Transmembrane Conductance Regulator in Sarcoplasmic Reticulum of Airway Smooth Muscle. Implications for Airway Contractility

    PubMed Central

    Cook, Daniel P.; Rector, Michael V.; Bouzek, Drake C.; Michalski, Andrew S.; Gansemer, Nicholas D.; Reznikov, Leah R.; Li, Xiaopeng; Stroik, Mallory R.; Ostedgaard, Lynda S.; Abou Alaiwa, Mahmoud H.; Thompson, Michael A.; Prakash, Y. S.; Krishnan, Ramaswamy; Meyerholz, David K.; Seow, Chun Y.

    2016-01-01

    Rationale: An asthma-like airway phenotype has been described in people with cystic fibrosis (CF). Whether these findings are directly caused by loss of CF transmembrane conductance regulator (CFTR) function or secondary to chronic airway infection and/or inflammation has been difficult to determine. Objectives: Airway contractility is primarily determined by airway smooth muscle. We tested the hypothesis that CFTR is expressed in airway smooth muscle and directly affects airway smooth muscle contractility. Methods: Newborn pigs, both wild type and with CF (before the onset of airway infection and inflammation), were used in this study. High-resolution immunofluorescence was used to identify the subcellular localization of CFTR in airway smooth muscle. Airway smooth muscle function was determined with tissue myography, intracellular calcium measurements, and regulatory myosin light chain phosphorylation status. Precision-cut lung slices were used to investigate the therapeutic potential of CFTR modulation on airway reactivity. Measurements and Main Results: We found that CFTR localizes to the sarcoplasmic reticulum compartment of airway smooth muscle and regulates airway smooth muscle tone. Loss of CFTR function led to delayed calcium reuptake following cholinergic stimulation and increased myosin light chain phosphorylation. CFTR potentiation with ivacaftor decreased airway reactivity in precision-cut lung slices following cholinergic stimulation. Conclusions: Loss of CFTR alters porcine airway smooth muscle function and may contribute to the airflow obstruction phenotype observed in human CF. Airway smooth muscle CFTR may represent a therapeutic target in CF and other diseases of airway narrowing. PMID:26488271

  7. [Orthodontics and the upper airway].

    PubMed

    Cobo Plana, J; de Carlos Villafranca, F; Macías Escalada, E

    2004-03-01

    One of the general aims of orthodontic treatment and of the combination of orthodontics and orthognathic surgery is to achieve good occlusion and aesthetic improvement, especially in cases of severe dentoskeletal deformities. However, on many occasions, the parameters of the upper airways are not taken into account when the aims of conventional treatment are fulfilled. Patients with obstructive alterations during sleep represent for the orthodontist a type of patient who differs from the normal; for them, treatment should include the objective of improving oxygen saturation. Here, functional considerations should outweigh purely aesthetic ones. It is important, when making an orthodontic, surgical or combined diagnosis for a patient, to bear in mind the impact that treatment may have on the upper airways. Good aesthetics should never be achieved for some of our patients at the expense of diminishing the capacity of their upper airways.

  8. Injury Induces Localized Airway Increases in Pro-Inflammatory Cytokines in Humans and Mice

    PubMed Central

    Jonker, Mark A.; Hermsen, Joshua L.; Gomez, F. Enrique; Sano, Yoshifumi

    2011-01-01

    Abstract Background Secretory immunoglobulin A (sIgA) increases in the airways of humans and mice after injury to protect against infection. The pro-inflammatory cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 are linked molecularly to sIgA production and secretion and are required for sIgA increases in the airway after injury in a mouse model. We investigated the injury effect on airway and serum concentrations to determine the source of the cytokines involved in the airway IgA response. Methods In the first experiment, TNF-α, IL-1β, and IL-6 concentrations in bronchoalveolar lavage (BAL) fluid and serum obtained from 11 ventilated trauma patients within 30 h of admission were compared with those in eight elective surgical patients. In the second experiment, male ICR mice received no injury (n = 7) or injury with sham celiotomy and neck incisions (n = 8) with sacrifice of all animals at 8 h for BAL fluid and serum cytokine measurements by enzyme-linked immunosorbent assay. Results Injured patients had significantly higher BAL fluid and serum TNF-α, IL-1β, and IL-6 concentrations, with greater increases in the BAL fluid than in the serum. Injured mice had significantly increased BAL fluid concentrations of TNF-α, IL-1β, and IL-6 without significant changes in serum TNF-α or IL-1β. Serum IL-6 increased significantly. Conclusions Injury significantly increases human and mouse airway TNF-α, IL-1β, and IL-6. Increases are greater in the airway than in serum, implying a local rather than a systemic stress response to injury. PMID:21166596

  9. Intrapulmonary Versus Nasal Transduction of Murine Airways With GP64-pseudotyped Viral Vectors

    PubMed Central

    Oakland, Mayumi; Maury, Wendy; McCray, Paul B; Sinn, Patrick L

    2013-01-01

    Persistent viral vector-mediated transgene expression in the airways requires delivery to cells with progenitor capacity and avoidance of immune responses. Previously, we observed that GP64-pseudotyped feline immunodeficiency virus (FIV)-mediated gene transfer was more efficient in the nasal airways than the large airways of the murine lung. We hypothesized that in vivo gene transfer was limited by immunological and physiological barriers in the murine intrapulmonary airways. Here, we systematically investigate multiple potential barriers to lentiviral gene transfer in the airways of mice. We show that GP64-FIV vector transduced primary cultures of well-differentiated murine nasal epithelia with greater efficiency than primary cultures of murine tracheal epithelia. We further demonstrate that neutrophils, type I interferon (IFN) responses, as well as T and B lymphocytes are not the major factors limiting the transduction of murine conducting airways. In addition, we observed better transduction of GP64-pseudotyped vesicular stomatitis virus (VSV) in the nasal epithelia compared with the intrapulmonary airways in mice. VSVG glycoprotein pseudotyped VSV transduced intrapulmonary epithelia with similar efficiency as nasal epithelia. Our results suggest that the differential transduction efficiency of nasal versus intrapulmonary airways by FIV vector is not a result of immunological barriers or surface area, but rather differential expression of cellular factors specific for FIV vector transduction. PMID:23360952

  10. Airway Assessment for Office Sedation/Anesthesia.

    PubMed

    Rosenberg, Morton B; Phero, James C

    2015-01-01

    Whenever a patient is about to receive sedation or general anesthesia, no matter what the technique, the preoperative assessment of the airway is one of the most important steps in ensuring patient safety and positive outcomes. This article, Part III in the series on airway management, is directed at the ambulatory office practice and focuses on predicting the success of advanced airway rescue techniques.

  11. Cyclooxygenase-1 overexpression decreases Basal airway responsiveness but not allergic inflammation.

    PubMed

    Card, Jeffrey W; Carey, Michelle A; Bradbury, J Alyce; Graves, Joan P; Lih, Fred B; Moorman, Michael P; Morgan, Daniel L; DeGraff, Laura M; Zhao, Yun; Foley, Julie F; Zeldin, Darryl C

    2006-10-01

    Pharmacological inhibition or genetic disruption of cyclooxygenase (COX)-1 or COX-2 exacerbates the inflammatory and functional responses of the lung to environmentally relevant stimuli. To further examine the contribution of COX-derived eicosanoids to basal lung function and to allergic lung inflammation, transgenic (Tr) mice were generated in which overexpression of human COX-1 was targeted to airway epithelium. Although no differences in basal respiratory or lung mechanical parameters were observed, COX-1 Tr mice had increased bronchoalveolar lavage fluid PGE(2) content compared with wild-type littermates (23.0 +/- 3.6 vs 8.4 +/- 1.4 pg/ml; p < 0.05) and exhibited decreased airway responsiveness to inhaled methacholine. In an OVA-induced allergic airway inflammation model, comparable up-regulation of COX-2 protein was observed in the lungs of allergic wild-type and COX-1 Tr mice. Furthermore, no genotype differences were observed in allergic mice in total cell number, eosinophil content (70 vs 76% of total cells, respectively), and inflammatory cytokine content of bronchoalveolar lavage fluid, or in airway responsiveness to inhaled methacholine (p > 0.05). To eliminate the presumed confounding effects of COX-2 up-regulation, COX-1 Tr mice were bred into a COX-2 null background. In these mice, the presence of the COX-1 transgene did not alter allergen-induced inflammation but significantly attenuated allergen-induced airway hyperresponsiveness, coincident with reduced airway leukotriene levels. Collectively, these data indicate that COX-1 overexpression attenuates airway responsiveness under basal conditions but does not influence allergic airway inflammation.

  12. Restricted access magnetic materials prepared by dual surface modification for selective extraction of therapeutic drugs from biological fluids

    NASA Astrophysics Data System (ADS)

    Wang, Yu; Wang, Yuxia; Chen, Lei; Wan, Qian-Hong

    2012-02-01

    Magnetic porous particles with dual functionality have been prepared by a two-step procedure and evaluated as novel restricted access materials for extraction of therapeutic agents from biological fluids. The magnetic silica particles served as scaffolds were first modified with diol groups, which were then converted to octadecyl esters through reaction with stearoyl chloride. In the second step, the octadecyl esters on the exterior surface were hydrolyzed by the action of lipase to yield magnetic particles with hydrophobic reversed-phase ligands on the inner surface and biocompatible diol groups on the outer surface. The restricted access behavior of the resulting materials was confirmed by differential binding of small molecules such as methotrexate (MTX), leucovorin (LV) and folic acid (FA) relative to bovine serum albumin. While MTX, LV and FA were all bound to the magnetic particles with high affinity, the adsorption of the protein was markedly reduced due to size exclusion effect. The utility of the magnetic particles for sample preparation was tested in solid-phase extraction of MTX, LV and FA from spiked human serum and the effects of the SPE conditions on the recovery of the analytes were systematically studied. Moreover, the magnetic particle-based sample preparation procedure coupled with reversed-phase liquid chromatography analysis was validated in terms of specificity, linearity and reproducibility. The method was shown to be free from interference of endogenous compounds and linear over the concentration range of 0.5-10 μg/mL for the three drugs studied. The limits of detection for the three drugs in serum were in the range of 0.160-0.302 μg/mL. Reproducibility expressed as the RSD of the recovery for ten replicated extractions at three different concentrations was found to be less than 8.93%. With a unique combination of surface functionality with magnetic cores, the restricted access magnetic particles may be adapted in automated and high

  13. Comments to Role of upper airway ultrasound in airway management.

    PubMed

    Lien, Wan-Ching

    2017-01-01

    Tracheal ultrasound can be an alternative diagnostic tool in airway management, besides traditional confirmatory methods such as capnography and auscultation. The standard image is a hyperechoic air-mucosa (A-M) interface with a reverberation artifact posteriorly (comet-tail artifact). If the second A-M interface appears, which we call a "double-tract sign," esophageal intubation is considered.

  14. Thermal Elasto-Hydrodynamic Lubrication by Non - Fluids with Rough Surfaces: its Application to Spur Gear Transmission.

    NASA Astrophysics Data System (ADS)

    Wang, Jian M.

    1995-01-01

    A theoretical investigation of the behavior of thermal elasto-hydrodynamic lubrication by non-Newtonian fluids under rough surfaces has been conducted. The study consists of two parts. In the first part, a general line contact elasto-hydrodynamic lubrication model is derived, which integrates several critical effects such as rheological characteristics of lubricants, roughness and temperature into one system. A more effective numerical algorithm is adopted to obtains the solutions under wide ranges of operating conditions. Observations and extensive discussions of the results lead to further understand the phenomena of the different interactions among the various factors in a elasto-hydrodynamic lubrication process. In the second part, the forgoing theory is applied to the specific problem of the spur gear transmission. Various kinematics and dynamics features associated with the lubrication process in the spur gear have been investigated. The results has shown that the pitch point EHL film thickness does not reliably represent the minimum EHL film thickness. The full thermal EHL calculation along the line of action is needed in order to predict the minimum film thickness and pressure peak more precisely. The actual location of the minimum film thickness along the line of action is strongly influenced by the dynamic load sharing profile. Surface roughness has the moderate effect on the gear lubrication. The effects become more significant when the roughness amplitudes approach the nominal film thickness. Non-Newtonian behavior of lubricants may significantly alter the level of the minimum film thickness and temperature distribution, but has only small effect on pressure peak.

  15. Inhalation of inactivated‑Mycobacterium phlei prevents asthma‑mediated airway hyperresponsiveness and airway eosinophilia in mice by reducing IL‑5 and IL‑13 levels.

    PubMed

    Ming, Moyu; Luo, Zhixi; Lv, Shengqiu; Li, Chaoqian

    2016-12-01

    The present study aimed to investigate whether inhalation of inactivated‑Mycobacterium phlei could prevent airway hyperresponsiveness and airway eosinophilia. A total of 24 male Balb/c mice were randomly divided into three groups: Normal control group (group A), asthma model group (group B) and the intervention group (group C), (8 mice/group). Group A mice were sensitized and with challenged saline and group B with ovalbumin (OVA). Group C mice were administered with aerosol Mycobacterium phlei once daily prior to the allergen challenge. Airway responsiveness in each group was assessed. All the animals were sacrificed and lung tissues, blood samples and bronchoalveolar lavage fluid (BALF) were harvested. Cell fractionation and differential cells were counted in serum and BALF. HE staining and alcian blue/periodic acid Schiff staining were used to measure airway eosinophilic inflammation and mucus production. The levels of the cytokines IL‑5, IL‑13 and IgE were measured in lung and BALF as determined by ELISA and reverse transcription‑quantitative polymerase chain reaction assays. The results indicated that inactivated‑Mycobacterium phlei suppressed the airway hyperresponsiveness and mitigated airway eosinophilia induced by a methacholine challenge, and significantly reduced the levels of cytokines IL‑5 and IL‑13 in lung tissue and IgE level in BALF when compared with the OVA‑sensitized mice. In conclusion, inhalation of inactivated‑Mycobacterium phlei could reduce OVA‑induced airway hyperresponsiveness and may be a potential alternative therapy for allergic airway diseases.

  16. μ-PIV/Shadowgraphy measurements to elucidate dynamic physicochemical interactions in a multiphase model of pulmonary airway reopening

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Eiichiro

    2010-10-01

    We employ micro-particle image velocimetry (μ-PIV) and shadowgraphy to measure the ensemble-averaged fluid-phase velocity field and interfacial geometry during pulsatile bubble propagation that includes a reverse-flow phase under influence of exogenous lung surfactant (Infasurf). Disease states such as respiratory distress syndrome (RDS) are characterized by insufficient pulmonary surfactant concentrations that enhance airway occlusion and collapse. Subsequent airway reopening, driven by mechanical ventilation, may generate damaging stresses that cause ventilator-induced lung injury (VILI). It is hypothesized that reverse flow may enhance surfactant uptake and protect the lung from VILI. The microscale observations conducted in this study will provide us with a significant understanding of dynamic physicochemical interactions that can be manipulated to reduce the magnitude of this damaging mechanical stimulus during airway reopening. Bubble propagation through a liquid-occluded fused glass capillary tube is controlled by linear-motor-driven syringe pumps that provide mean and sinusoidal velocity components. A translating microscope stage mechanically subtracts the mean velocity of the bubble tip in order to hold the progressing bubble tip in the microscope field of view. To optimize the signal-to-noise ratio near the bubble tip, μ-PIV and shadow images are recorded in separate trials then combined during post-processing with help of a custom-designed micro scale marker. Non-specific binding of Infasurf proteins to the channel wall is controlled by oxidation and chemical treatment of the glass surface. The colloidal stability and dynamic/static surface properties of the Infasurf-PIV particle solution are carefully adjusted based on Langmuir trough measurements. The Finite Time Lyapunov Exponent (FTLE) is computed to provide a Lagrangian perspective for comparison with our boundary element predictions.

  17. Allergen-induced airway remodeling is impaired in galectin-3 deficient mice1

    PubMed Central

    Ge, Xiao Na; Bahaie, Nooshin S.; Kang, Bit Na; Hosseinkhani, Reza M.; Ha, Sung Gil; Frenzel, Elizabeth M.; Liu, Fu-Tong; Rao, Savita P.; Sriramarao, P.

    2010-01-01

    The role played by the β-galactoside-binding lectin galectin-3 (Gal-3) in airway remodeling, a characteristic feature of asthma that leads to airway dysfunction and poor clinical outcome in humans, was investigated in a murine model of chronic allergic airway inflammation. Wild-type (WT) and Gal-3 knock-out (KO) mice were subjected to repetitive allergen challenge with ovalbumin (OVA) up to 12 weeks and bronchoalveolar lavage fluid (BALF) and lung tissue collected after the last challenge were evaluated for cellular features associated with airway remodeling. Compared to WT mice, chronic OVA challenge in Gal-3 KO mice resulted in diminished remodeling of the airways with significantly reduced mucus secretion, sub-epithelial fibrosis, smooth muscle thickness, and peribronchial angiogenesis. The higher degree of airway remodeling in WT mice was associated with higher Gal-3 expression in the BALF as well as lung tissue. Cell counts in BALF and lung immunohistology demonstrated that eosinophil infiltration in OVA-challenged Gal-3 KO mice was significantly reduced compared to WT mice. Evaluation of cellular mediators associated with eosinophil recruitment and airway remodeling revealed that levels of eotaxin-1, IL-5, IL-13, FIZZ1 and TGF-β were substantially lower in Gal-3 KO mice. Finally, leukocytes from Gal-3 KO mice demonstrated decreased trafficking (rolling) on vascular endothelial adhesion molecules compared to WT cells. Overall, these studies demonstrate that Gal-3 is an important lectin that promotes airway remodeling via airway recruitment of inflammatory cells, specifically eosinophils, and the development of a Th2 phenotype as well as increased expression of eosinophil-specific chemokines, pro-fibrogenic and angiogenic mediators. PMID:20543100

  18. Investigation of pulmonary acoustic simulation: comparing airway model generation techniques

    NASA Astrophysics Data System (ADS)

    Henry, Brian; Dai, Zoujun; Peng, Ying; Mansy, Hansen A.; Sandler, Richard H.; Royston, Thomas

    2014-03-01

    Alterations in the structure and function of the pulmonary system that occur in disease or injury often give rise to measurable spectral, spatial and/or temporal changes in lung sound production and transmission. These changes, if properly quantified, might provide additional information about the etiology, severity and location of trauma, injury, or pathology. With this in mind, the authors are developing a comprehensive computer simulation model of pulmonary acoustics, known as The Audible Human Project™. Its purpose is to improve our understanding of pulmonary acoustics and to aid in interpreting measurements of sound and vibration in the lungs generated by airway insonification, natural breath sounds, and external stimuli on the chest surface, such as that used in elastography. As a part of this development process, finite element (FE) models were constructed of an excised pig lung that also underwent experimental studies. Within these models, the complex airway structure was created via two methods: x-ray CT image segmentation and through an algorithmic means called Constrained Constructive Optimization (CCO). CCO was implemented to expedite the segmentation process, as airway segments can be grown digitally. These two approaches were used in FE simulations of the surface motion on the lung as a result of sound input into the trachea. Simulation results were compared to experimental measurements. By testing how close these models are to experimental measurements, we are evaluating whether CCO can be used as a means to efficiently construct physiologically relevant airway trees.

  19. Wave propagation in fluid-conveying viscoelastic carbon nanotubes under longitudinal magnetic field with thermal and surface effect via nonlocal strain gradient theory

    NASA Astrophysics Data System (ADS)

    Zhen, Yaxin; Zhou, Lin

    2017-03-01

    Based on nonlocal strain gradient theory, wave propagation in fluid-conveying viscoelastic single-walled carbon nanotubes (SWCNTs) is studied in this paper. With consideration of thermal effect and surface effect, wave equation is derived for fluid-conveying viscoelastic SWCNTs under longitudinal magnetic field utilizing Euler-Bernoulli beam theory. The closed-form expressions are derived for the frequency and phase velocity of the wave motion. The influences of fluid flow velocity, structural damping coefficient, temperature change, magnetic flux and surface effect are discussed in detail. SWCNTs’ viscoelasticity reduces the wave frequency of the system and the influence gets remarkable with the increase of wave number. The fluid in SWCNTs decreases the frequency of wave propagation to a certain extent. The frequency (phase velocity) gets larger due to the existence of surface effect, especially when the diameters of SWCNTs and the wave number decrease. The wave frequency increases with the increase of the longitudinal magnetic field, while decreases with the increase of the temperature change. The results may be helpful for better understanding the potential applications of SWCNTs in nanotechnology.

  20. Slip effects on a mixed convection flow of a third-grade fluid near the orthogonal stagnation point on a vertical surface

    NASA Astrophysics Data System (ADS)

    Javed, T.; Mustafa, I.

    2016-05-01

    A mixed convection flow of a third-grade fluid near the orthogonal stagnation point on a vertical surface with slip and viscous dissipation effects is investigated. The governing partial differential equations for the third-grade fluid are converted into a system of nonlinear ordinary differential equations by using a similarity transformation. The effects of various parameters, including the Weissenberg number, third-grade parameter, local Reynolds number, Prandtl number, Eckert number, mixed convection parameter, velocity slip, and thermal slip on the velocity and temperature profiles, local skin friction coefficient, and local Nusselt number are discussed.

  1. The Lung Microbiome and Airway Disease.

    PubMed

    Lynch, Susan V

    2016-12-01

    A growing body of literature has demonstrated relationships between the composition of the airway microbiota (mixed-species communities of microbes that exist in the respiratory tract) and critical features of immune response and pulmonary function. These studies provide evidence that airway inflammatory status and capacity for repair are coassociated with specific taxonomic features of the airway microbiome. Although directionality has yet to be established, the fact that microbes are known drivers of inflammation and tissue damage suggests that in the context of chronic inflammatory airway disease, the composition and, more importantly, the function, of the pulmonary microbiome represent critical factors in defining airway disease outcomes.

  2. Airway nerves: in vitro electrophysiology.

    PubMed

    Fox, Alyson

    2002-06-01

    Recording the activity of single airway sensory fibres or neuronal cell bodies in vitro has allowed detailed characterisation of fibre types and membrane properties. Fibre types can be identified by their conduction velocities and further studied by the application of drugs to their receptive field. C-fibres are sensitive to mechanical stimuli and a range of irritant chemicals (bradykinin, capsaicin, low pH, platelet-activating factor), whereas Adelta-fibres are relatively insensitive to chemical stimuli and appear to correlate to the rapidly adapting receptors identified in airways in vivo. Their site of origin also differs: upper airway C-fibres arise predominantly from the jugular ganglion and Adelta-fibres from the jugular and nodose ganglia. Intracellular recording from cell bodies in the ganglia has revealed a calcium-dependent potassium current common to many putative C-fibre cell bodies. This slow after hyperpolarisation current may be inhibited by stimuli that excite and sensitise C-fibres - this could be an important mechanism underlying the sensitisation of C-fibres in airway irritability.

  3. Airway malacia in children with achondroplasia.

    PubMed

    Dessoffy, Kimberly E; Modaff, Peggy; Pauli, Richard M

    2014-02-01

    This study was undertaken to assess the frequency of airway malacia in infants and young children with achondroplasia, a population well known to be at risk for a variety of respiratory probl