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Sample records for airway surface layer

  1. 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

  2. Airway surface liquid depth imaged by surface laser reflectance microscopy.

    PubMed

    Thiagarajah, Jay R; Song, Yuanlin; Derichs, Nico; Verkman, A S

    2010-09-01

    The thin layer of liquid at the surface of airway epithelium, the airway surface liquid (ASL), is important in normal airway physiology and in the pathophysiology of cystic fibrosis. At present, the best method to measure ASL depth involves scanning confocal microscopy after staining with an aqueous-phase fluorescent dye. We describe here a simple, noninvasive imaging method to measure ASL depth by reflectance imaging of an epithelial mucosa in which the surface is illuminated at a 45-degree angle by an elongated 13-microm wide rectangular beam produced by a 670-nm micro-focus laser. The principle of the method is that air-liquid, liquid-liquid, and liquid-cell interfaces produce distinct specular or diffuse reflections that can be imaged to give a micron-resolution replica of the mucosal surface. The method was validated using fluid layers of specified thicknesses and applied to measure ASL depth in cell cultures and ex vivo fragments of pig trachea. In addition, the method was adapted to measure transepithelial fluid transport from the dynamics of fluid layer depth. Compared with confocal imaging, ASL depth measurement by surface laser reflectance microscopy does not require dye staining or costly instrumentation, and can potentially be adapted for in vivo measurements using fiberoptics. PMID:20713545

  3. Regulation of human airway surface liquid.

    PubMed

    Widdicombe, J H; Widdicombe, J G

    1995-01-01

    Human airways are lined with a film of liquid from 5-100 microns in depth, consisting of a periciliary sol around and a mucous gel above the cilia. Microscopical studies have shown the sol to be invariably the same depth as the length of the cilia, and we discuss possible reasons for this. The composition and sources of the airway surface liquid are also described. In addition the forces regulating its volume are analyzed. Several airway diseases are characterised by dramatic changes in the volume and composition of airway liquid. We review recent research suggesting that the accumulation of airway mucous secretions in cystic fibrosis is caused by alterations in active transport of ions and water across both the surface and gland epithelia. PMID:7740210

  4. REGIONAL DIFFERENCES IN AIRWAY SURFACE LIQUID COMPOSITION

    EPA Science Inventory

    Liquid from canine airway surfaces was absorbed onto filter paper strips and analyzed. In resting conditions, tracheal surface liquid was hyperosmolal (330 mosmol/kg H2O) compared to plasma with raised Na(+1) (158 meq/l), Cl(-1) (134 meq/l), K(-1) (28 meq/l), and HCO3(-1) (32 meq...

  5. Airway Surface Mycosis in Chronic Th2-Associated Airway Disease

    PubMed Central

    Porter, Paul; Lim, Dae Jun; Maskatia, Zahida Khan; Mak, Garbo; Tsai, Chu-Lin; Citardi, Martin J; Fakhri, Samer; Shaw, Joanne L.; Fothergil, Annette; Kheradmand, Farrah; Corry, David B; Luong, Amber

    2014-01-01

    Background Environmental fungi have been linked to T helper type 2 (Th2) cell-related airway inflammation and the Th2-associated chronic airway diseases asthma, chronic rhinosinusitis with nasal polyps (CRSwNP) and allergic fungal rhinosinusitis (AFRS), but whether these organisms participate directly or indirectly in disease pathology remains unknown. Objective To determine the frequency of fungus isolation and fungus-specific immunity in Th2-associated and non-associated airway disease patients. Methods Sinus lavage fluid and blood were collected from sinus surgery patients (n=118) including CRS patients with and without nasal polyps and AFRS and non-CRS/non-asthmatic control patients. Asthma status was deteremined from medical history. Sinus lavage fluids were cultured and directly examined for evidence of viable fungi. Peripheral blood mononuclear cells were restimulated with fungal antigens in an enzyme linked immunocell spot (ELISpot) assay to determine total memory fungus-specific IL-4-secreting cells. These data were compared to fungus-specific IgE levels measured from plasma by ELISA. Results Filamentous fungi were significantly more commonly cultured from Th2-associated airway disease subjects (asthma, CRSwNP, or AFRS: n=68) compared to non-Th2-associated control patients (n=31); 74% vs 16% respectively, p<0.001. Both fungus-specific IL-4 ELISpot (n=48) and specific IgE (n=70) data correlated with Th2-associated diseases (sensitivity 73% and specificity 100% vs. 50% and 77%, respectively). Conclusions The frequent isolation of fungi growing directly within the airways accompanied by specific immunity to these organisms only in patients with Th2-associated chronic airway diseases suggests that fungi participate directly in the pathogenesis of these conditions. Efforts to eradicate airway fungi from the airways should be considered in selected patients. Clinical Implications Airway fungi may contribute to the expression of sinusitis with nasal polyps and

  6. 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.

  7. Compliant layer chucking surface

    SciTech Connect

    Blaedel, Kenneth L.; Spence, Paul A.; Thompson, Samuel L.

    2004-12-28

    A method and apparatus are described wherein a thin layer of complaint material is deposited on the surface of a chuck to mitigate the deformation that an entrapped particle might cause in the part, such as a mask or a wafer, that is clamped to the chuck. The harder particle will embed into the softer layer as the clamping pressure is applied. The material composing the thin layer could be a metal or a polymer for vacuum or electrostatic chucks. It may be deposited in various patterns to affect an interrupted surface, such as that of a "pin" chuck, thereby reducing the probability of entrapping a particle.

  8. 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

  9. Inhibition of airway surface fluid absorption by cholinergic stimulation.

    PubMed

    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

  10. 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

  11. Molecular insights into the physiology of the ‘thin film’ of airway surface liquid

    PubMed Central

    Boucher, R C

    1999-01-01

    The epithelia that line the airways of the lung exhibit two general functions: (1) airway epithelia in all regions ‘defend’ the lung against infectious and noxious agents; and (2) airway epithelia in the proximal regions replenish water lost from airway surfaces, i.e. the ‘insensible water loss’, consequent to conditioning inspired air. How airway epithelia perform both functions, and co-ordinate them in health and disease, is the subject of this review. PMID:10200413

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

    PubMed

    Zabner, J; Seiler, M P; Launspach, J L; Karp, P H; Kearney, W R; Look, D C; Smith, J J; Welsh, M J

    2000-10-10

    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. PMID:11027360

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

    PubMed Central

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

    2000-01-01

    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. PMID:11027360

  14. Normal and Cystic Fibrosis Airway Surface Liquid Homeostasis

    PubMed Central

    Tarran, Robert; Button, Brian; Picher, Maryse; Paradiso, Anthony M.; Ribeiro, Carla M.; Lazarowski, Eduardo R.; Zhang, Liqun; Collins, Peter L.; Pickles, Raymond J.; Fredberg, Jeffrey J.; Boucher, Richard C.

    2010-01-01

    Mammalian airways normally regulate the volume of a thin liquid layer, the periciliary liquid (PCL), to facilitate the mucus clearance component of lung defense. Studies under standard (static) culture conditions revealed that normal airway epithelia possess an adenosine-regulated pathway that blends Na+ absorption and Cl− secretion to optimize PCL volume. In cystic fibrosis (CF), the absence of CF transmembrane conductance regulator results in a failure of adenosine regulation of PCL volume, which is predicted to initiate mucus stasis and infection. However, under conditions that mimic the phasic motion of the lung in vivo, ATP release into PCL was increased, CF ion transport was rebalanced, and PCL volume was restored to levels adequate for lung defense. This ATP signaling system was vulnerable, however, to insults that trigger CF bacterial infections, such as viral (respiratory syncitial virus) infections, which up-regulated extracellular ATPase activity and abolished motion-dependent ATP regulation of CF PCL height. These studies demonstrate (i) how the normal coordination of opposing ion transport pathways to maintain PCL volume is disrupted in CF, (ii) the hitherto unknown role of phasic motion in regulating key aspects of normal and CF innate airways defense, and (iii) that maneuvers directed at increasing motion-induced nucleotide release may be therapeutic in CF patients. PMID:16087672

  15. Reduced airway surface pH impairs bacterial killing in the porcine cystic fibrosis lung.

    PubMed

    Pezzulo, Alejandro A; Tang, Xiao Xiao; Hoegger, Mark J; Alaiwa, Mahmoud H Abou; Ramachandran, Shyam; Moninger, Thomas O; Karp, Phillip H; Wohlford-Lenane, Christine L; Haagsman, Henk P; van Eijk, Martin; Bánfi, Botond; Horswill, Alexander R; Stoltz, David A; McCray, Paul B; Welsh, Michael J; Zabner, Joseph

    2012-07-01

    Cystic fibrosis (CF) is a life-shortening disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Although bacterial lung infection and the resulting inflammation cause most of the morbidity and mortality, how the loss of CFTR function first disrupts airway host defence has remained uncertain. To investigate the abnormalities that impair elimination when a bacterium lands on the pristine surface of a newborn CF airway, we interrogated the viability of individual bacteria immobilized on solid grids and placed onto the airway surface. As a model, we studied CF pigs, which spontaneously develop hallmark features of CF lung disease. At birth, their lungs lack infection and inflammation, but have a reduced ability to eradicate bacteria. Here we show that in newborn wild-type pigs, the thin layer of airway surface liquid (ASL) rapidly kills bacteria in vivo, when removed from the lung and in primary epithelial cultures. Lack of CFTR reduces bacterial killing. We found that the ASL pH was more acidic in CF pigs, and reducing pH inhibited the antimicrobial activity of ASL. Reducing ASL pH diminished bacterial killing in wild-type pigs, and, conversely, increasing ASL pH rescued killing in CF pigs. These results directly link the initial host defence defect to the loss of CFTR, an anion channel that facilitates HCO(3)(-) transport. Without CFTR, airway epithelial HCO(3)(-) secretion is defective, the ASL pH falls and inhibits antimicrobial function, and thereby impairs the killing of bacteria that enter the newborn lung. These findings suggest that increasing ASL pH might prevent the initial infection in patients with CF, and that assaying bacterial killing could report on the benefit of therapeutic interventions. PMID:22763554

  16. Reduced Airway Surface pH Impairs Bacterial Killing in the Porcine Cystic Fibrosis Lung

    PubMed Central

    Pezzulo, Alejandro A.; Tang, Xiao Xiao; Hoegger, Mark J.; Abou Alaiwa, Mahmoud H.; Ramachandran, Shyam; Moninger, Thomas O.; Karp, Phillip H.; Wohlford-Lenane, Christine L.; Haagsman, Henk P.; van Eijk, Martin; Bánfi, Botond; Horswill, Alexander R.; Stoltz, David A.; McCray, Paul B.; Welsh, Michael J.; Zabner, Joseph

    2012-01-01

    Cystic fibrosis (CF) is a life-shortening disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene 1. Although bacterial lung infection and the resulting inflammation cause most of the morbidity and mortality, how loss of CFTR first disrupts airway host defense has remained uncertain 2–6. We asked what abnormalities impair eradication when a bacterium lands on the pristine surface of a newborn CF airway? To investigate these defects, we interrogated the viability of individual bacteria immobilized on solid grids and placed on the airway surface. As a model we studied CF pigs, which spontaneously develop hallmark features of CF lung disease 7,8. At birth, their lungs lack infection and inflammation, but have a reduced ability to eradicate bacteria 8. Here we show that in newborn wild-type pigs, the thin layer of airway surface liquid (ASL) rapidly killed bacteria in vivo, when removed from the lung, and in primary epithelial cultures. Lack of CFTR reduced bacterial killing. We found that ASL pH was more acidic in CF, and reducing pH inhibited the antimicrobial activity of ASL. Reducing ASL pH diminished bacterial killing in wild-type pigs, and increasing ASL pH rescued killing in CF pigs. These results directly link the initial host defense defect to loss of CFTR, an anion channel that facilitates HCO3− transport 9–13. Without CFTR, airway epithelial HCO3− secretion is defective, ASL pH falls and inhibits antimicrobial function, and thereby impairs killing of bacteria that enter the newborn lung. These findings suggest that increasing ASL pH might prevent the initial infection in patients with CF and that assaying bacterial killing could report on the benefit of therapeutic interventions. PMID:22763554

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

    PubMed Central

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

    2014-01-01

    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. PMID:25136096

  18. The effect of viscoelasticity on the stability of a pulmonary airway liquid layer

    NASA Astrophysics Data System (ADS)

    Halpern, David; Fujioka, Hideki; Grotberg, James B.

    2010-01-01

    The lungs consist of a network of bifurcating airways that are lined with a thin liquid film. This film is a bilayer consisting of a mucus layer on top of a periciliary fluid layer. Mucus is a non-Newtonian fluid possessing viscoelastic characteristics. Surface tension induces flows within the layer, which may cause the lung's airways to close due to liquid plug formation if the liquid film is sufficiently thick. The stability of the liquid layer is also influenced by the viscoelastic nature of the liquid, which is modeled using the Oldroyd-B constitutive equation or as a Jeffreys fluid. To examine the role of mucus alone, a single layer of a viscoelastic fluid is considered. A system of nonlinear evolution equations is derived using lubrication theory for the film thickness and the film flow rate. A uniform film is initially perturbed and a normal mode analysis is carried out that shows that the growth rate g for a viscoelastic layer is larger than for a Newtonian fluid with the same viscosity. Closure occurs if the minimum core radius, Rmin(t), reaches zero within one breath. Solutions of the nonlinear evolution equations reveal that Rmin normally decreases to zero faster with increasing relaxation time parameter, the Weissenberg number We. For small values of the dimensionless film thickness parameter ɛ, the closure time, tc, increases slightly with We, while for moderate values of ɛ, ranging from 14% to 18% of the tube radius, tc decreases rapidly with We provided the solvent viscosity is sufficiently small. Viscoelasticity was found to have little effect for ɛ >0.18, indicating the strong influence of surface tension. The film thickness parameter ɛ and the Weissenberg number We also have a significant effect on the maximum shear stress on tube wall, max(τw), and thus, potentially, an impact on cell damage. Max(τw) increases with ɛ for fixed We, and it decreases with increasing We for small We provided the solvent viscosity parameter is sufficiently

  19. The effect of viscoelasticity on the stability of a pulmonary airway liquid layer

    PubMed Central

    Halpern, David; Fujioka, Hideki; Grotberg, James B.

    2010-01-01

    The lungs consist of a network of bifurcating airways that are lined with a thin liquid film. This film is a bilayer consisting of a mucus layer on top of a periciliary fluid layer. Mucus is a non-Newtonian fluid possessing viscoelastic characteristics. Surface tension induces flows within the layer, which may cause the lung’s airways to close due to liquid plug formation if the liquid film is sufficiently thick. The stability of the liquid layer is also influenced by the viscoelastic nature of the liquid, which is modeled using the Oldroyd-B constitutive equation or as a Jeffreys fluid. To examine the role of mucus alone, a single layer of a viscoelastic fluid is considered. A system of nonlinear evolution equations is derived using lubrication theory for the film thickness and the film flow rate. A uniform film is initially perturbed and a normal mode analysis is carried out that shows that the growth rate g for a viscoelastic layer is larger than for a Newtonian fluid with the same viscosity. Closure occurs if the minimum core radius, Rmin(t), reaches zero within one breath. Solutions of the nonlinear evolution equations reveal that Rmin normally decreases to zero faster with increasing relaxation time parameter, the Weissenberg number We. For small values of the dimensionless film thickness parameter ε, the closure time, tc, increases slightly with We, while for moderate values of ε, ranging from 14% to 18% of the tube radius, tc decreases rapidly with We provided the solvent viscosity is sufficiently small. Viscoelasticity was found to have little effect for ε>0.18, indicating the strong influence of surface tension. The film thickness parameter ε and the Weissenberg number We also have a significant effect on the maximum shear stress on tube wall, max(τw), and thus, potentially, an impact on cell damage. Max(τw) increases with ε for fixed We, and it decreases with increasing We for small We provided the solvent viscosity parameter is sufficiently

  20. 17β-Estradiol inhibits Ca2+-dependent homeostasis of airway surface liquid volume in human cystic fibrosis airway epithelia

    PubMed Central

    Coakley, Ray D.; Sun, Hengrui; Clunes, Lucy A.; Rasmussen, Julia E.; Stackhouse, James R.; Okada, Seiko F.; Fricks, Ingrid; Young, Steven L.; Tarran, Robert

    2008-01-01

    Normal airways homeostatically regulate the volume of airway surface liquid (ASL) through both cAMP- and Ca2+-dependent regulation of ion and water transport. In cystic fibrosis (CF), a genetic defect causes a lack of cAMP-regulated CFTR activity, leading to diminished Cl– and water secretion from airway epithelial cells and subsequent mucus plugging, which serves as the focus for infections. Females with CF exhibit reduced survival compared with males with CF, although the mechanisms underlying this sex-related disadvantage are unknown. Despite the lack of CFTR, CF airways retain a limited capability to regulate ASL volume, as breathing-induced ATP release activates salvage purinergic pathways that raise intracellular Ca2+ concentration to stimulate an alternate pathway to Cl– secretion. We hypothesized that estrogen might affect this pathway by reducing the ability of airway epithelia to respond appropriately to nucleotides. We found that uridine triphosphate–mediated (UTP-mediated) Cl– secretion was reduced during the periovulatory estrogen maxima in both women with CF and normal, healthy women. Estrogen also inhibited Ca2+ signaling and ASL volume homeostasis in non-CF and CF airway epithelia by attenuating Ca2+ influx. This inhibition of Ca2+ signaling was prevented and even potentiated by estrogen antagonists such as tamoxifen, suggesting that antiestrogens may be beneficial in the treatment of CF lung disease because they increase Cl– secretion in the airways. PMID:19033671

  1. Surface layers of bacteria.

    PubMed Central

    Beveridge, T J; Graham, L L

    1991-01-01

    Since bacteria are so small, microscopy has traditionally been used to study them as individual cells. To this end, electron microscopy has been a most powerful tool for studying bacterial surfaces; the viewing of macromolecular arrangements of some surfaces is now possible. This review compares older conventional electron-microscopic methods with new cryotechniques currently available and the results each has produced. Emphasis is not placed on the methodology but, rather, on the importance of the results in terms of our perception of the makeup and function of bacterial surfaces and their interaction with the surrounding environment. Images PMID:1723487

  2. [Surface layers of methanotrophic bacteria].

    PubMed

    Khmelenina, V N; Suzina, N E; Trotsenko, Iu A

    2013-01-01

    Structural and functional characteristics of the regular glycoprotein layers in prokaryotes are analyzed with a special emphasis on aerobic methanotrophic bacteria. S-layers are present at the surfaces of Methylococcus, Methylothermus, and Methylomicrobium cells. Different Methylomicrobium species either synthesize S-layers with planar (p2, p4) symmetry or form cup-shaped or conicalstructures with hexagonal (p6) symmetry. A unique, copper-binding polypeptide 'CorA'/MopE (27/45 kDa), which is coexpressed with the diheme periplasmic cytochrome c peroxidase 'CorB'/Mca (80 kDa) was found in Methylomicrobium album BG8, Methylomicrobium alcaliphilum 20Z, and Methylococcus capsulatus Bath. This tandem of the surface proteins is functionally analogous to a new siderophore, methanobactin. Importantly, no 'CorA'/MopE homologue was found in methanotrophs not forming S-layers. The role of surface proteins in copper metabolism and initial methane oxidation is discussed. PMID:25509389

  3. Airway Surface Dehydration Aggravates Cigarette Smoke-Induced Hallmarks of COPD in Mice

    PubMed Central

    Seys, Leen J. M.; Verhamme, Fien M.; Dupont, Lisa L.; Desauter, Elke; Duerr, Julia; Seyhan Agircan, Ayca; Conickx, Griet; Joos, Guy F.; Brusselle, Guy G.

    2015-01-01

    Introduction Airway surface dehydration, caused by an imbalance between secretion and absorption of ions and fluid across the epithelium and/or increased epithelial mucin secretion, impairs mucociliary clearance. Recent evidence suggests that this mechanism may be implicated in chronic obstructive pulmonary disease (COPD). However, the role of airway surface dehydration in the pathogenesis of cigarette smoke (CS)-induced COPD remains unknown. Objective We aimed to investigate in vivo the effect of airway surface dehydration on several CS-induced hallmarks of COPD in mice with airway-specific overexpression of the β-subunit of the epithelial Na+ channel (βENaC). Methods βENaC-Tg mice and wild-type (WT) littermates were exposed to air or CS for 4 or 8 weeks. Pathological hallmarks of COPD, including goblet cell metaplasia, mucin expression, pulmonary inflammation, lymphoid follicles, emphysema and airway wall remodelling were determined and lung function was measured. Results Airway surface dehydration in βENaC-Tg mice aggravated CS-induced airway inflammation, mucin expression and destruction of alveolar walls and accelerated the formation of pulmonary lymphoid follicles. Moreover, lung function measurements demonstrated an increased compliance and total lung capacity and a lower resistance and hysteresis in βENaC-Tg mice, compared to WT mice. CS exposure further altered lung function measurements. Conclusions We conclude that airway surface dehydration is a risk factor that aggravates CS-induced hallmarks of COPD. PMID:26066648

  4. Glycobiology of surface layer proteins.

    PubMed

    Schäffer, C; Messner, P

    2001-07-01

    Over the last two decades, a significant change of perception has taken place regarding prokaryotic glycoproteins. For many years, protein glycosylation was assumed to be limited to eukaryotes; but now, a wealth of information on structure, function, biosynthesis and molecular biology of prokaryotic glycoproteins has accumulated, with surface layer (S-layer) glycoproteins being one of the best studied examples. With the designation of Archaea as a second prokaryotic domain of life, the occurrence of glycosylated S-layer proteins had been considered a taxonomic criterion for differentiation between Bacteria and Archaea. Extensive structural investigations, however, have demonstrated that S-layer glycoproteins are present in both domains. Among Gram-positive bacteria, S-layer glycoproteins have been identified only in bacilli. In Gram-negative organisms, their presence is still not fully investigated; presently, there is no indication for their existence in this class of bacteria. Extensive biochemical studies of the S-layer glycoprotein from Halobacterium halobium have, at least in part, unravelled the glycosylation pathway in Archaea; molecular biological analyses of these pathways have not been performed, so far. Significant observations concern the occurrence of unusual linkage regions both in archaeal and bacterial S-layer glycoproteins. Regarding S-layer glycoproteins of bacteria, first genetic data have shed some light into the molecular organization of the glycosylation machinery in this domain. In addition to basic S-layer glycoprotein research, the biotechnological application potential of these molecules has been explored. With the development of straightforward molecular biological methods, fascinating possibilities for the expression of prokaryotic glycoproteins will become available. S-layer glycoprotein research has opened up opportunities for the production of recombinant glycosylation enzymes and tailor-made S-layer glycoproteins in large quantities

  5. Protein composition of bronchoalveolar lavage fluid and airway surface liquid from newborn pigs

    PubMed Central

    Bartlett, Jennifer A.; Albertolle, Matthew E.; Wohlford-Lenane, Christine; Pezzulo, Alejandro A.; Zabner, Joseph; Niles, Richard K.; Fisher, Susan J.; McCray, Paul B.

    2013-01-01

    The airway mucosa and the alveolar surface form dynamic interfaces between the lung and the external environment. The epithelial cells lining these barriers elaborate a thin liquid layer containing secreted peptides and proteins that contribute to host defense and other functions. The goal of this study was to develop and apply methods to define the proteome of porcine lung lining liquid, in part, by leveraging the wealth of information in the Sus scrofa database of Ensembl gene, transcript, and protein model predictions. We developed an optimized workflow for detection of secreted proteins in porcine bronchoalveolar lavage (BAL) fluid and in methacholine-induced tracheal secretions [airway surface liquid (ASL)]. We detected 674 and 3,858 unique porcine-specific proteins in BAL and ASL, respectively. This proteome was composed of proteins representing a diverse range of molecular classes and biological processes, including host defense, molecular transport, cell communication, cytoskeletal, and metabolic functions. Specifically, we detected a significant number of secreted proteins with known or predicted roles in innate and adaptive immunity, microbial killing, or other aspects of host defense. In greatly expanding the known proteome of the lung lining fluid in the pig, this study provides a valuable resource for future studies using this important animal model of pulmonary physiology and disease. PMID:23709621

  6. 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.

  7. Automated acquisition and analysis of airway surface liquid height by confocal microscopy

    PubMed Central

    Choi, Hyun-Chul; Kim, Christine Seul Ki

    2015-01-01

    The airway surface liquid (ASL) is a thin-liquid layer that lines the luminal side of airway epithelia. ASL contains many molecules that are involved in primary innate defense in the lung. Measurement of ASL height on primary airway cultures by confocal microscopy is a powerful tool that has enabled researchers to study ASL physiology and pharmacology. Previously, ASL image acquisition and analysis were performed manually. However, this process is time and labor intensive. To increase the throughput, we have developed an automatic ASL measurement technique that combines a fully automated confocal microscope with novel automatic image analysis software that was written with image processing techniques derived from the computer science field. We were able to acquire XZ ASL images at the rate of ∼1 image/s in a reproducible fashion. Our automatic analysis software was able to analyze images at the rate of ∼32 ms/image. As proofs of concept, we generated a time course for ASL absorption and a dose response in the presence of SPLUNC1, a known epithelial sodium channel inhibitor, on human bronchial epithelial cultures. Using this approach, we determined the IC50 for SPLUNC1 to be 6.53 μM. Furthermore, our technique successfully detected a difference in ASL height between normal and cystic fibrosis (CF) human bronchial epithelial cultures and detected changes in ATP-stimulated Cl−/ASL secretion. We conclude that our automatic ASL measurement technique can be applied for repeated ASL height measurements with high accuracy and consistency and increased throughput. PMID:26001773

  8. 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.

  9. Synergistic and additive killing by antimicrobial factors found in human airway surface liquid.

    PubMed

    Singh, P K; Tack, B F; McCray, P B; Welsh, M J

    2000-11-01

    Airway surface liquid contains multiple factors thought to provide a first line of defense against bacteria deposited in the airways. Although the antimicrobial action of individual factors has been studied, less is known about how they work in combination. We examined the combined action of six antimicrobial peptides found in airway surface liquid. The paired combinations of lysozyme-lactoferrin, lysozyme-secretory leukocyte protease inhibitor (SLPI), and lactoferrin-SLPI were synergistic. The triple combination of lysozyme, lactoferrin, and SLPI showed even greater synergy. Other combinations involving the human beta-defensins, LL-37, and tobramycin (often administered to cystic fibrosis patients by inhalation) were additive. Because the airway surface liquid salt concentration may be elevated in cystic fibrosis patients, we examined the effect of salt on the synergistic combinations. As the ionic strength increased, synergistic interactions were lost. Our data suggest that the antibacterial potency of airway surface liquid may be significantly increased by synergistic and additive interactions between antimicrobial factors. These results also suggest that increased salt concentrations that may exist in cystic fibrosis could inhibit airway defenses by diminishing these synergistic interactions. PMID:11053013

  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. PMID:25068642

  11. Regulation of the epithelial Na+ channel and airway surface liquid volume by serine proteases

    PubMed Central

    Gaillard, Erol A.; Kota, Pradeep; Gentzsch, Martina; Dokholyan, Nikolay V.; Stutts, M. Jackson

    2010-01-01

    Mammalian airways are protected from infection by a thin film of airway surface liquid (ASL) which covers airway epithelial surfaces and acts as a lubricant to keep mucus from adhering to the epithelial surface. Precise regulation of ASL volume is essential for efficient mucus clearance and too great a reduction in ASL volume causes mucus dehydration and mucus stasis which contributes to chronic airway infection. The epithelial Na+ channel (ENaC) is the rate-limiting step that governs Na+ absorption in the airways. Recent in vitro and in vivo data have demonstrated that ENaC is a critical determinant of ASL volume and hence mucus clearance. ENaC must be cleaved by either intracellular furin-type proteases or extracellular serine proteases to be active and conduct Na+, and this process can be inhibited by protease inhibitors. ENaC can be regulated by multiple pathways, and once proteolytically cleaved ENaC may then be inhibited by intracellular second messengers such as cAMP and PIP2. In the airways, however, regulation of ENaC by proteases seems to be the predominant mode of regulation since knockdown of either endogenous serine proteases such as prostasin, or inhibitors of ENaC proteolysis such as SPLUNC1, has large effects on ENaC activity in airway epithelia. In this review, we shall discuss how ENaC is proteolytically cleaved, how this process can regulate ASL volume, and how its failure to operate correctly may contribute to chronic airway disease. PMID:20401730

  12. Particle Deposition During Airway Closure

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

    Inhaled aerosol particles deposit in the lung and may be from environmental, toxic, or medical therapy sources. While much research focuses on inspiratory deposition, primarily at airway bifurcations due to inertial impaction, there are other mechanisms that allow the particles to reach the airway surface, such as gravitational settling and diffusion depending on particle size. We introduce a new mechanism not previously studied, i.e. aerosol deposition from airway closure. The airways are lined with a liquid layer. Due to the surface tension driven instability, a liquid plug can form from this layer which blocks the airway. This process of airway closure tends to occur toward the end of expiration. In this study, the efficiency of the impaction of the particles during airway closure will be investigated. The particles will be released from the upstream of the airway and convected by the air flow and deposited onto the closing liquid layer. We solve the governing equations using a finite volume approach in conjunction with a sharp interface method for the interfaces. Once the velocity field of the gas flow is obtained, the path of the particles will be calculated and the efficiency of the deposition can be estimated. We acknowledge support from the National Institutes of Health grant number NIH HL85156.

  13. Liquid Movement Across the Surface Epithelium of Large Airways

    PubMed Central

    Chambers, Lucy A.; Rollins, Brett M.; Tarran, Robert

    2009-01-01

    The cystic fibrosis conductance regulator CFTR gene is found on chromosome 7 (Kerem et al., 1989; Riordan et al., 1989) and encodes for a 1,480 amino acid protein which is present in the plasma membrane of epithelial cells (Anderson et al., 1992). This protein appears to have many functions, but a unifying theme is that it acts as a protein kinase C- and cyclic AMP-regulated Cl- channel (Winpenny et al., 1995; Jia et al., 1997). In the superficial epithelium of the conducting airways, CFTR is involved in Cl- secretion (Boucher, 2003) and also acts as a regulator of the epithelial Na+ channel (ENaC) and hence Na+ absorption (Boucher et al., 1986; Stutts et al., 1995). In this chapter, we will discuss the regulation of these two ion channels, and how they can influence liquid movement across the superficial airway epithelium. PMID:17692578

  14. An improved method for fixation of the respiratory epithelial surface with the mucous and surfactant layers

    SciTech Connect

    Hulbert, W.C.; Forster, B.B.; Laird, W.; Pihl, C.E.; Walker, D.C.

    1982-10-01

    A new technique for the stabilization of the mucous layers in the upper respiratory tree is described. The methodology combines perfusion of the thoracic vasculature through the carotid, thyroid, and bronchial arteries, with aerosolization of fixative onto the airway surface through a tracheostomy. The biphasic nature of the mucous layer in healthy animals is confirmed and is compared with the nature of the mucus in animals exposed to cigarette smoke. The fundamental advantage of the technique is that, because airway surface phenomena are stabilized, more thorough correlates of physiology and morphology can be accomplished. The intrapulmonary airways and parenchyma are also fixed by using this technique, and the results are discussed. A preliminary communication using this technique to document leukocyte transit across the respiratory mucosa has been published.

  15. 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

  16. Cigarette smoke exposure induces CFTR internalization and insolubility, leading to airway surface liquid dehydration.

    PubMed

    Clunes, Lucy A; Davies, Catrin M; Coakley, Raymond D; Aleksandrov, Andrei A; Henderson, Ashley G; Zeman, Kirby L; Worthington, Erin N; Gentzsch, Martina; Kreda, Silvia M; Cholon, Deborah; Bennett, William D; Riordan, John R; Boucher, Richard C; Tarran, Robert

    2012-02-01

    Cigarette smoke (CS) exposure induces mucus obstruction and the development of chronic bronchitis (CB). While many of these responses are determined genetically, little is known about the effects CS can exert on pulmonary epithelia at the protein level. We, therefore, tested the hypothesis that CS exerts direct effects on the CFTR protein, which could impair airway hydration, leading to the mucus stasis characteristic of both cystic fibrosis and CB. In vivo and in vitro studies demonstrated that CS rapidly decreased CFTR activity, leading to airway surface liquid (ASL) volume depletion (i.e., dehydration). Further studies revealed that CS induced internalization of CFTR. Surprisingly, CS-internalized CFTR did not colocalize with lysosomal proteins. Instead, the bulk of CFTR shifted to a detergent-resistant fraction within the cell and colocalized with the intermediate filament vimentin, suggesting that CS induced CFTR movement into an aggresome-like, perinuclear compartment. To test whether airway dehydration could be reversed, we used hypertonic saline (HS) as an osmolyte to rehydrate ASL. HS restored ASL height in CS-exposed, dehydrated airway cultures. Similarly, inhaled HS restored mucus transport and increased clearance in patients with CB. Thus, we propose that CS exposure rapidly impairs CFTR function by internalizing CFTR, leading to ASL dehydration, which promotes mucus stasis and a failure of mucus clearance, leaving smokers at risk for developing CB. Furthermore, our data suggest that strategies to rehydrate airway surfaces may provide a novel form of therapy for patients with CB. PMID:21990373

  17. Cigarette smoke exposure induces CFTR internalization and insolubility, leading to airway surface liquid dehydration

    PubMed Central

    Clunes, Lucy A.; Davies, Catrin M.; Coakley, Raymond D.; Aleksandrov, Andrei A.; Henderson, Ashley G.; Zeman, Kirby L.; Worthington, Erin N.; Gentzsch, Martina; Kreda, Silvia M.; Cholon, Deborah; Bennett, William D.; Riordan, John R.; Boucher, Richard C.; Tarran, Robert

    2012-01-01

    Cigarette smoke (CS) exposure induces mucus obstruction and the development of chronic bronchitis (CB). While many of these responses are determined genetically, little is known about the effects CS can exert on pulmonary epithelia at the protein level. We, therefore, tested the hypothesis that CS exerts direct effects on the CFTR protein, which could impair airway hydration, leading to the mucus stasis characteristic of both cystic fibrosis and CB. In vivo and in vitro studies demonstrated that CS rapidly decreased CFTR activity, leading to airway surface liquid (ASL) volume depletion (i.e., dehydration). Further studies revealed that CS induced internalization of CFTR. Surprisingly, CS-internalized CFTR did not colocalize with lysosomal proteins. Instead, the bulk of CFTR shifted to a detergent-resistant fraction within the cell and colocalized with the intermediate filament vimentin, suggesting that CS induced CFTR movement into an aggresome-like, perinuclear compartment. To test whether airway dehydration could be reversed, we used hypertonic saline (HS) as an osmolyte to rehydrate ASL. HS restored ASL height in CS-exposed, dehydrated airway cultures. Similarly, inhaled HS restored mucus transport and increased clearance in patients with CB. Thus, we propose that CS exposure rapidly impairs CFTR function by internalizing CFTR, leading to ASL dehydration, which promotes mucus stasis and a failure of mucus clearance, leaving smokers at risk for developing CB. Furthermore, our data suggest that strategies to rehydrate airway surfaces may provide a novel form of therapy for patients with CB.—Clunes, L. A., Davies, C. M., Coakley, R. D., Aleksandrov, A. A., Henderson, A. G., Zeman, K. L., Worthington, E. N., Gentzsch, M., Kreda, S. M., Cholon, D., Bennett, W. D., Riordan, J. R., Boucher, R. C., Tarran, R. Cigarette smoke exposure induces CFTR internalization and insolubility, leading to airway surface liquid dehydration. PMID:21990373

  18. Cell Surface Human Airway Trypsin-Like Protease Is Lost During Squamous Cell Carcinogenesis

    PubMed Central

    DUHAIME, MICHAEL J.; PAGE, KHALIPH O.; VARELA, FAUSTO A.; MURRAY, ANDREW S.; SILVERMAN, MICHAEL E.; ZORATTI, GINA L.; LIST, KARIN

    2016-01-01

    Cancer progression is accompanied by increased levels of extracellular proteases that are capable of remodeling the extracellular matrix, as well as cleaving and activating growth factors and receptors that are involved in pro-cancerous signaling pathways. Several members of the type II transmembrane serine protease (TTSP) family have been shown to play critical roles in cancer progression, however, the expression or function of the TTSP Human Airway Trypsin-like protease (HAT) in carcinogenesis has not been examined. In the present study we aimed to determine the expression of HAT during squamous cell carcinogenesis. HAT transcript is present in several tissues containing stratified squamous epithelium and decreased expression is observed in carcinomas. We determined that HAT protein is consistently expressed on the cell surface in suprabasal/apical layers of squamous cells in healthy cervical and esophageal epithelia. To assess whether HAT protein is differentially expressed in normal tissue versus tissue in different stages of carcinogenesis, we performed a comprehensive immunohistochemical analysis of HAT protein expression levels and localization in arrays of paraffin embedded human cervical and esophageal carcinomas compared to the corresponding normal tissue. We found that HAT protein is expressed in the non-proliferating, differentiated cellular strata and is lost during the dedifferentiation of epithelial cells, a hallmark of squamous cell carcinogenesis. Thus, HAT expression may potentially be useful as a marker for clinical grading and assessment of patient prognosis in squamous cell carcinomas. PMID:26297835

  19. Cell Surface Human Airway Trypsin-Like Protease Is Lost During Squamous Cell Carcinogenesis.

    PubMed

    Duhaime, Michael J; Page, Khaliph O; Varela, Fausto A; Murray, Andrew S; Silverman, Michael E; Zoratti, Gina L; List, Karin

    2016-07-01

    Cancer progression is accompanied by increased levels of extracellular proteases that are capable of remodeling the extracellular matrix, as well as cleaving and activating growth factors and receptors that are involved in pro-cancerous signaling pathways. Several members of the type II transmembrane serine protease (TTSP) family have been shown to play critical roles in cancer progression, however, the expression or function of the TTSP Human Airway Trypsin-like protease (HAT) in carcinogenesis has not been examined. In the present study we aimed to determine the expression of HAT during squamous cell carcinogenesis. HAT transcript is present in several tissues containing stratified squamous epithelium and decreased expression is observed in carcinomas. We determined that HAT protein is consistently expressed on the cell surface in suprabasal/apical layers of squamous cells in healthy cervical and esophageal epithelia. To assess whether HAT protein is differentially expressed in normal tissue versus tissue in different stages of carcinogenesis, we performed a comprehensive immunohistochemical analysis of HAT protein expression levels and localization in arrays of paraffin embedded human cervical and esophageal carcinomas compared to the corresponding normal tissue. We found that HAT protein is expressed in the non-proliferating, differentiated cellular strata and is lost during the dedifferentiation of epithelial cells, a hallmark of squamous cell carcinogenesis. Thus, HAT expression may potentially be useful as a marker for clinical grading and assessment of patient prognosis in squamous cell carcinomas. PMID:26297835

  20. 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

  1. Optimal Graph Search Based Segmentation of Airway Tree Double Surfaces Across Bifurcations

    PubMed Central

    Chen, Danny Z.; Tawhai, Merryn H.; Wu, Xiaodong; Hoffman, Eric A.; Sonka, Milan

    2014-01-01

    Identification of both the luminal and the wall areas of the bronchial tree structure from volumetric X-ray computed tomography (CT) data sets is of critical importance in distinguishing important phenotypes within numerous major lung diseases including chronic obstructive pulmonary diseases (COPD) and asthma. However, accurate assessment of the inner and outer airway wall surfaces of a complete 3-D tree structure is difficult due to their complex nature, particularly around the branch areas. In this paper, we extend a graph search based technique (LOGISMOS) to simultaneously identify multiple inter-related surfaces of branching airway trees. We first perform a presegmentation of the input 3-D image to obtain basic information about the tree topology. The presegmented image is resampled along judiciously determined paths to produce a set of vectors of voxels (called voxel columns). The resampling process utilizes medial axes to ensure that voxel columns of appropriate lengths and directions are used to capture the object surfaces without interference. A geometric graph is constructed whose edges connect voxels in the resampled voxel columns and enforce validity of the smoothness and separation constraints on the sought surfaces. Cost functions with directional information are employed to distinguish inner and outer walls. The assessment of wall thickness measurement on a CT-scanned double-wall physical phantom (patterned after an in vivo imaged human airway tree) achieved highly accurate results on the entire 3-D tree. The observed mean signed error of wall thickness ranged from −0.09 ± 0.24 mm to 0.07 ± 0.23 mm in bifurcating/nonbifurcating areas. The mean unsigned errors were 0.16 ± 0.12 mm to 0.20 ± 0.11 mm. When the airway wall surface was partitioned into meaningful subregions, the airway wall thickness accuracy was the same in most tested bifurcation/nonbifurcation and carina/noncarina regions (p=NS). Once validated on phantoms, our method was applied

  2. Uncertainties in Surface Layer Modeling

    NASA Astrophysics Data System (ADS)

    Pendergrass, W.

    2015-12-01

    A central problem for micrometeorologists has been the relationship of air-surface exchange rates of momentum and heat to quantities that can be predicted with confidence. The flux-gradient profile developed through Monin-Obukhov Similarity Theory (MOST) provides an integration of the dimensionless wind shear expression where is an empirically derived expression for stable and unstable atmospheric conditions. Empirically derived expressions are far from universally accepted (Garratt, 1992, Table A5). Regardless of what form of these relationships might be used, their significance over any short period of time is questionable since all of these relationships between fluxes and gradients apply to averages that might rarely occur. It is well accepted that the assumption of stationarity and homogeneity do not reflect the true chaotic nature of the processes that control the variables considered in these relationships, with the net consequence that the levels of predictability theoretically attainable might never be realized in practice. This matter is of direct relevance to modern prognostic models which construct forecasts by assuming the universal applicability of relationships among averages for the lower atmosphere, which rarely maintains an average state. Under a Cooperative research and Development Agreement between NOAA and Duke Energy Generation, NOAA/ATDD conducted atmospheric boundary layer (ABL) research using Duke renewable energy sites as research testbeds. One aspect of this research has been the evaluation of legacy flux-gradient formulations (the ϕ functions, see Monin and Obukhov, 1954) for the exchange of heat and momentum. At the Duke Energy Ocotillo site, NOAA/ATDD installed sonic anemometers reporting wind and temperature fluctuations at 10Hz at eight elevations. From these observations, ϕM and ϕH were derived from a two-year database of mean and turbulent wind and temperature observations. From this extensive measurement database, using a

  3. Regulation of Murine Airway Surface Liquid Volume by CFTR and Ca2+-activated Cl− Conductances

    PubMed Central

    Tarran, Robert; Loewen, Matthew E.; Paradiso, Anthony M.; Olsen, John C.; Gray, Micheal A.; Argent, Barry E.; Boucher, Richard C.; Gabriel, Sherif E.

    2002-01-01

    Two Cl− conductances have been described in the apical membrane of both human and murine proximal airway epithelia that are thought to play predominant roles in airway hydration: (1) CFTR, which is cAMP regulated and (2) the Ca2+-activated Cl− conductance (CaCC) whose molecular identity is uncertain. In addition to second messenger regulation, cross talk between these two channels may also exist and, whereas CFTR is absent or defective in cystic fibrosis (CF) airways, CaCC is preserved, and may even be up-regulated. Increased CaCC activity in CF airways is controversial. Hence, we have investigated the effects of CFTR on CaCC activity and have also assessed the relative contributions of these two conductances to airway surface liquid (ASL) height (volume) in murine tracheal epithelia. We find that CaCC is up-regulated in intact murine CF tracheal epithelia, which leads to an increase in UTP-mediated Cl−/volume secretion. This up-regulation is dependent on cell polarity and is lost in nonpolarized epithelia. We find no role for an increased electrical driving force in CaCC up-regulation but do find an increased Ca2+ signal in response to mucosal nucleotides that may contribute to the increased Cl−/volume secretion seen in intact epithelia. CFTR plays a critical role in maintaining ASL height under basal conditions and accordingly, ASL height is reduced in CF epithelia. In contrast, CaCC does not appear to significantly affect basal ASL height, but does appear to be important in regulating ASL height in response to released agonists (e.g., mucosal nucleotides). We conclude that both CaCC and the Ca2+ signal are increased in CF airway epithelia, and that they contribute to acute but not basal regulation of ASL height. PMID:12198094

  4. Secretory response induced by essential oils on airway surface fluid: a pharmacological MRI study.

    PubMed

    Nicolato, Elena; Boschi, Federico; Marzola, Pasquina; Sbarbati, Andrea

    2009-07-30

    Using pharmacological magnetic resonance imaging, we have performed an in vivo evaluation of the secretory response induced by essential oils in the rat airway. Aim of the work was to establish a computerized method to assess the efficacy of volatile compounds in spatially localized areas without the bias derived by subjective evaluation. Magnetic resonance experiments were carried out using a 4.7 T horizontal magnet. In the trachea, airway surface fluid was easily identified for its high intensity signal. The tracheal glands were also easily visible. The oesophageal lumen was usually collapsed and was identifiable only in the presence of intraluminal liquid. Scotch pine essential oil inhalation significantly increased the surface fluid in the middle portion of the trachea and the increase was visible at both 5 and 10 min. A lesser secretory response was detected after rosemary essential oil inhalation even though the response was significant with respect to the control in particular at 10 min. No secretory response was detected after peppermint essential oil inhalation both at 5 and 10 min. The data obtained in the present work demonstrate a chemically induced airway secretion. The availability of a pharmacological magnetic resonance imaging approach opens new perspectives to test the action of volatile compounds on the airway. PMID:19422906

  5. Water molecules orientation in surface layer

    NASA Astrophysics Data System (ADS)

    Klingo, V. V.

    2000-08-01

    The water molecules orientation has been investigated theoretically in the water surface layer. The surface molecule orientation is determined by the direction of a molecule dipole moment in relation to outward normal to the water surface. Entropy expressions of the superficial molecules in statistical meaning and from thermodynamical approach to a liquid surface tension have been found. The molecules share directed opposite to the outward normal that is hydrogen protons inside is equal 51.6%. 48.4% water molecules are directed along to surface outward normal that is by oxygen inside. A potential jump at the water surface layer amounts about 0.2 volts.

  6. Basolateral localization of fiber receptors limits adenovirus infection from the apical surface of airway epithelia.

    PubMed

    Walters, R W; Grunst, T; Bergelson, J M; Finberg, R W; Welsh, M J; Zabner, J

    1999-04-01

    Recent identification of two receptors for the adenovirus fiber protein, coxsackie B and adenovirus type 2 and 5 receptor (CAR), and the major histocompatibility complex (MHC) Class I alpha-2 domain allows the molecular basis of adenoviral infection to be investigated. Earlier work has shown that human airway epithelia are resistant to infection by adenovirus. Therefore, we examined the expression and localization of CAR and MHC Class I in an in vitro model of well differentiated, ciliated human airway epithelia. We found that airway epithelia express CAR and MHC Class I. However, neither receptor was present in the apical membrane; instead, both were polarized to the basolateral membrane. These findings explain the relative resistance to adenovirus infection from the apical surface. In contrast, when the virus was applied to the basolateral surface, gene transfer was much more efficient because of an interaction of adenovirus fiber with its receptors. In addition, when the integrity of the tight junctions was transiently disrupted, apically applied adenovirus gained access to the basolateral surface and enhanced gene transfer. These data suggest that the receptors required for efficient infection are not available on the apical surface, and interventions that allow access to the basolateral space where fiber receptors are located increase gene transfer efficiency. PMID:10187807

  7. Stable water layers on solid surfaces.

    PubMed

    Hong, Ying-Jhan; Tai, Lin-Ai; Chen, Hung-Jen; Chang, Pin; Yang, Chung-Shi; Yew, Tri-Rung

    2016-02-17

    Liquid layers adhered to solid surfaces and that are in equilibrium with the vapor phase are common in printing, coating, and washing processes as well as in alveoli in lungs and in stomata in leaves. For such a liquid layer in equilibrium with the vapor it faces, it has been generally believed that, aside from liquid lumps, only a very thin layer of the liquid, i.e., with a thickness of only a few nanometers, is held onto the surface of the solid, and that this adhesion is due to van der Waals forces. A similar layer of water can remain on the surface of a wall of a microchannel after evaporation of bulk water creates a void in the channel, but the thickness of such a water layer has not yet been well characterized. Herein we showed such a water layer adhered to a microchannel wall to be 100 to 170 nm thick and stable against surface tension. The water layer thickness was measured using electron energy loss spectroscopy (EELS), and the water layer structure was characterized by using a quantitative nanoparticle counting technique. This thickness was found for channel gap heights ranging from 1 to 5 μm. Once formed, the water layers in the microchannel, when sealed, were stable for at least one week without any special care. Our results indicate that the water layer forms naturally and is closely associated only with the surface to which it adheres. Our study of naturally formed, stable water layers may shed light on topics from gas exchange in alveoli in biology to the post-wet-process control in the semiconductor industry. We anticipate our report to be a starting point for more detailed research and understanding of the microfluidics, mechanisms and applications of gas-liquid-solid systems. PMID:26856872

  8. Layering of ionic liquids on rough surfaces

    NASA Astrophysics Data System (ADS)

    Sheehan, Alexis; Jurado, L. Andres; Ramakrishna, Shivaprakash N.; Arcifa, Andrea; Rossi, Antonella; Spencer, Nicholas D.; Espinosa-Marzal, Rosa M.

    2016-02-01

    Understanding the behavior of ionic liquids (ILs) either confined between rough surfaces or in rough nanoscale pores is of great relevance to extend studies performed on ideally flat surfaces to real applications. In this work we have performed an extensive investigation of the structural forces between two surfaces with well-defined roughness (<9 nm RMS) in 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide by atomic force microscopy. Statistical studies of the measured layer thicknesses, layering force, and layering frequency reveal the ordered structure of the rough IL-solid interface. Our work shows that the equilibrium structure of the interfacial IL strongly depends on the topography of the contact.Understanding the behavior of ionic liquids (ILs) either confined between rough surfaces or in rough nanoscale pores is of great relevance to extend studies performed on ideally flat surfaces to real applications. In this work we have performed an extensive investigation of the structural forces between two surfaces with well-defined roughness (<9 nm RMS) in 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide by atomic force microscopy. Statistical studies of the measured layer thicknesses, layering force, and layering frequency reveal the ordered structure of the rough IL-solid interface. Our work shows that the equilibrium structure of the interfacial IL strongly depends on the topography of the contact. Electronic supplementary information (ESI) available: Optimized geometries and sizes for [HMIM] Ntf2, SEM images of the smooth and rough colloids, frequency of occurrence of layering in the resolved force-distance curves for all investigated systems with [HMIM] Ntf2, layer size and layering force measured with a sharp tip on mica for the same IL, and results of the kinetics experiments. See DOI: 10.1039/c5nr07805a

  9. Effect of surface ionization on wetting layers

    NASA Technical Reports Server (NTRS)

    Kayser, R. F.

    1986-01-01

    A surface ionization model due to Langmuir is generalized to liquid mixtures of polar and nonpolar components in contact with ionizable substrates. When a predominantly nonpolar mixture is near a miscibility gap, thick wetting layers of the conjugate polar phase form on the substrate. Such charged layers can be much thicker than similar wetting layers stabilized by dispersion forces. This model may explain the 0.4- to 0.6-micron-thick wetting layers formed in stirred mixtures of nitromethane and carbon disulfide in contact with glass.

  10. Surface layer effects on waste glass corrosion

    SciTech Connect

    Feng, X.

    1993-12-31

    Water contact subjects waste glass to chemical attack that results in the formation of surface alteration layers. Two principal hypotheses have been advanced concerning the effect of surface alteration layers on continued glass corrosion: (1) they act as a mass transport barrier and (2) they influence the chemical affinity of the glass reaction. In general, transport barrier effects have been found to be less important than affinity effects in the corrosion of most high-level nuclear waste glasses. However, they can be important under some circumstances, for example, in a very alkaline solution, in leachants containing Mg ions, or under conditions where the matrix dissolution rate is very low. The latter suggests that physical barrier effect may affect the long-term glass dissolution rate. Surface layers influence glass reaction affinity through the effects of the altered glass and secondary phases on the solution chemistry. The reaction affinity may be controlled by various precipitates and crystalline phases, amorphous silica phases, gel layer, or all the components of the glass. The surface alteration layers influence radionuclide release mainly through colloid formation, crystalline phase incorporation, and gel layer retention. This paper reviews current understanding and uncertainties.

  11. Regulation of normal and cystic fibrosis airway surface liquid volume by phasic shear stress.

    PubMed

    Tarran, Robert; Button, Brian; Boucher, Richard C

    2006-01-01

    The physical removal of viruses and bacteria on the mucociliary escalator is an important aspect of the mammalian lung's innate defense mechanism. The volume of airway surface liquid (ASL) present in the respiratory tract is a critical determinant of both mucus hydration and the rate of mucus clearance from the lung. ASL volume is maintained by the predominantly ciliated epithelium via coordinated regulation of (a) absorption, by the epithelial Na+ channel, and (b) secretion, by the Ca2+-activated Cl- channel (CaCC) and CFTR. This review provides an update on our current understanding of how shear stress regulates ASL volume height in normal and cystic fibrosis (CF) airway epithelia through extracellular ATP- and adenosine (ADO)-mediated pathways that modulate ion transport and ASL volume homeostasis. We also discuss (a) how derangement of the ADO-CFTR pathway renders CF airways vulnerable to viral infections that deplete ASL volume and produce mucus stasis, and (b) potential shear stress-dependent therapies for CF. PMID:16460283

  12. Effect of surface tension of mucosal lining liquid on upper airway mechanics in anesthetized humans.

    PubMed

    Kirkness, Jason P; Eastwood, Peter R; Szollosi, Irene; Platt, Peter R; Wheatley, John R; Amis, Terence C; Hillman, David R

    2003-07-01

    Upper airway (UA) patency may be influenced by surface tension (gamma) operating within the (UAL). We examined the role of gamma of UAL in the maintenance of UA patency in eight isoflurane-anesthetized supine human subjects breathing via a nasal mask connected to a pneumotachograph attached to a pressure delivery system. We evaluated 1). mask pressure at which the UA closed (Pcrit), 2). UA resistance upstream from the site of UA collapse (RUS), and 3). mask pressure at which the UA reopened (Po). A multiple pressure-transducer catheter was used to identify the site of airway closure (velopharyngeal in all subjects). UAL samples (0.2 microl) were collected, and the gamma of UAL was determined by using the "pull-off force" technique. Studies were performed before and after the intrapharyngeal instillation of 5 ml of exogenous surfactant (Exosurf, Glaxo Smith Kline). The gamma of UAL decreased from 61.9 +/- 4.1 (control) to 50.3 +/- 5.0 mN/m (surfactant; P < 0.02). Changes in Po, RUS, and Po - Pcrit (change = control - surfactant) were positively correlated with changes in gamma (r2 > 0.6; P < 0.02) but not with changes in Pcrit (r2 = 0.4; P > 0.9). In addition, mean peak inspiratory airflow (no flow limitation) significantly increased (P < 0.04) from 0.31 +/- 0.06 (control) to 0.36 +/- 0.06 l/s (surfactant). These findings suggest that gamma of UAL exerts a force on the UA wall that hinders airway opening. Instillation of exogenous surfactant into the UA lowers the gamma of UAL, thus increasing UA patency and augmenting reopening of the collapsed airway. PMID:12626492

  13. The surface layer for free-surface turbulent flows

    NASA Astrophysics Data System (ADS)

    Shen, Lian; Zhang, Xiang; Yue, Dick K. P.; Triantafyllou, George S.

    1999-05-01

    Direct numerical simulation (DNS) is used to examine low Froude number free-surface turbulence (FST) over a two-dimensional mean shear flow. The Navier Stokes equations are solved using a finite-difference scheme with a grid resolution of 1283. Twenty separate simulations are conducted to calculate the statistics of the flow. Based on the velocity deficit and the vertical extent of the shear of the mean flow, the Reynolds number is 1000 and the Froude number is 0.7. We identify conceptually and numerically the surface layer, which is a thin region adjacent to the free surface characterized by fast variations of the horizontal vorticity components. This surface layer is caused by the dynamic zero-stress boundary conditions at the free surface and lies inside a thicker blockage (or ‘source’) layer, which is due to the kinematic boundary condition at the free surface. The importance of the outer blockage layer is manifested mainly in the redistribution of the turbulence intensity, i.e. in the increase of the horizontal velocity fluctuations at the expense of the vertical velocity fluctuation. A prominent feature of FST is vortex connections to the free surface which occur inside the surface layer. It is found that as hairpin-shaped vortex structures approach the free surface, their ‘head’ part is dissipated quickly in the surface layer, while the two ‘legs’ connect almost perpendicularly to the free surface. Analysis of the evolution of surface-normal vorticity based on vortex surface-inclination angle shows that both dissipation and stretching decrease dramatically after connection. As a result, vortex structures connected to the free surface are persistent and decay slowly relative to non-connected vorticities. The effects of surface and blockage layers on the turbulence statistics of length scales, Reynolds-stress balance, and enstrophy dynamics are examined, which elucidate clearly the different turbulence mechanisms operating in the respective near-surface

  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. The Epithelial Anion Transporter Pendrin Is Induced by Allergy and Rhinovirus Infection, Regulates Airway Surface Liquid, and Increases Airway Reactivity and Inflammation in an Asthma Model1

    PubMed Central

    Nakagami, Yasuhiro; Favoreto, Silvio; Zhen, Guohua; Park, Sung-Woo; Nguyenvu, Louis T.; Kuperman, Douglas A.; Dolganov, Gregory M.; Huang, Xiaozhu; Boushey, Homer A.; Avila, Pedro C.; Erle, David J.

    2008-01-01

    Asthma exacerbations can be triggered by viral infections or allergens. The Th2 cytokines IL-13 and IL-4 are produced during allergic responses and cause increases in airway epithelial cell mucus, electrolyte and water secretion into the airway surface liquid (ASL). Since ASL dehydration can cause airway inflammation and obstruction, ion transporters could play a role in pathogenesis of asthma exacerbations. We previously reported that expression of the epithelial cell anion transporter pendrin is markedly increased in response to IL-13. Here we show that pendrin plays a role in allergic airway disease and in regulation of ASL thickness. Pendrin-deficient mice had less allergen-induced airway hyperreactivity and inflammation than control mice although other aspects of the Th2 response were preserved. In cultures of IL-13-stimulated mouse tracheal epithelial cells, pendrin deficiency caused an increase in ASL thickness, suggesting that reductions in allergen-induced hyperreactivity and inflammation in pendrin-deficient mice result from improved ASL hydration. To determine whether pendrin might also play a role in virus-induced exacerbations of asthma, we measured pendrin mRNA expression in human subjects with naturally occurring common colds caused by rhinovirus and found a 4.9-fold-increase in mean expression during colds. Studies of cultured human bronchial epithelial cells indicated that this increase could be explained by the combined effects of rhinovirus and IFN-γ, a Th1 cytokine induced during virus infection. We conclude that pendrin regulates ASL thickness and may be an important contributor to asthma exacerbations induced by viral infections or allergens. PMID:18641360

  16. Surface shear rheology of saponin adsorption layers.

    PubMed

    Golemanov, Konstantin; Tcholakova, Slavka; Denkov, Nikolai; Pelan, Edward; Stoyanov, Simeon D

    2012-08-21

    Saponins are a wide class of natural surfactants, with molecules containing a rigid hydrophobic group (triterpenoid or steroid), connected via glycoside bonds to hydrophilic oligosaccharide chains. These surfactants are very good foam stabiliziers and emulsifiers, and show a range of nontrivial biological activities. The molecular mechanisms behind these unusual properties are unknown, and, therefore, the saponins have attracted significant research interest in recent years. In our previous study (Stanimirova et al. Langmuir 2011, 27, 12486-12498), we showed that the triterpenoid saponins extracted from Quillaja saponaria plant (Quillaja saponins) formed adsorption layers with unusually high surface dilatational elasticity, 280 ± 30 mN/m. In this Article, we study the shear rheological properties of the adsorption layers of Quillaja saponins. In addition, we study the surface shear rheological properties of Yucca saponins, which are of steroid type. The experimental results show that the adsorption layers of Yucca saponins exhibit purely viscous rheological response, even at the lowest shear stress applied, whereas the adsorption layers of Quillaja saponins behave like a viscoelastic two-dimensional body. For Quillaja saponins, a single master curve describes the data for the viscoelastic creep compliance versus deformation time, up to a certain critical value of the applied shear stress. Above this value, the layer compliance increases, and the adsorption layers eventually transform into viscous ones. The experimental creep-recovery curves for the viscoelastic layers are fitted very well by compound Voigt rheological model. The obtained results are discussed from the viewpoint of the layer structure and the possible molecular mechanisms, governing the rheological response of the saponin adsorption layers. PMID:22830458

  17. Surface state and normal layer effects

    SciTech Connect

    Klemm, R.A.; Ledvij, M.; Liu, S.H.

    1995-08-01

    In addition to the conducting CuO{sub 2} (S) layers, most high-T{sub c} superconductors also contain other conducting (N) layers, which are only superconducting due to the proximity effect. The combination of S and N layers can give rise to complicated electronic densities of states, leading to quasilinear penetration depth and NMR relaxation rate behavior at low temperatures. Surface states can also complicate the analysis of tunneling and, photoemission measurements. Moreover, geometrical considerations and in homogeneously trapped flux axe possible explanations of the paramagnetic Meissner effect and of corner and ring SQUID experiments. Hence, all of the above experiments could be consistent with isotropic s-wave superconductivity within the S layers.

  18. Characteristics of the Martian atmosphere surface layer

    NASA Technical Reports Server (NTRS)

    Clow, G. D.; Haberle, R. M.

    1990-01-01

    Elements of various terrestrial boundary layer models are extended to Mars in order to estimate sensible heat, latent heat, and momentum fluxes within the Martian atmospheric surface ('constant flux') layer. The atmospheric surface layer consists of an interfacial sublayer immediately adjacent to the ground and an overlying fully turbulent surface sublayer where wind-shear production of turbulence dominates buoyancy production. Within the interfacial sublayer, sensible and latent heat are transported by non-steady molecular diffusion into small-scale eddies which intermittently burst through this zone. Both the thickness of the interfacial sublayer and the characteristics of the turbulent eddies penetrating through it depend on whether airflow is aerodynamically smooth or aerodynamically rough, as determined by the Roughness Reynold's number. Within the overlying surface sublayer, similarity theory can be used to express the mean vertical windspeed, temperature, and water vapor profiles in terms of a single parameter, the Monin-Obukhov stability parameter. To estimate the molecular viscosity and thermal conductivity of a CO2-H2O gas mixture under Martian conditions, parameterizations were developed using data from the TPRC Data Series and the first-order Chapman-Cowling expressions; the required collision integrals were approximated using the Lenard-Jones potential. Parameterizations for specific heat and binary diffusivity were also determined. The Brutsart model for sensible and latent heat transport within the interfacial sublayer for both aerodynamically smooth and rough airflow was experimentally tested under similar conditions, validating its application to Martian conditions. For the surface sublayer, the definition of the Monin-Obukhov length was modified to properly account for the buoyancy forces arising from water vapor gradients in the Martian atmospheric boundary layer. It was found that under most Martian conditions, the interfacial and surface

  19. Electronic structure of bacterial surface protein layers

    SciTech Connect

    Maslyuk, Volodymyr V.; Mertig, Ingrid; Bredow, Thomas; Mertig, Michael; Vyalikh, Denis V.; Molodtsov, Serguei L.

    2008-01-15

    We report an approach for the calculation of the electronic density of states of the dried two-dimensional crystalline surface protein layer (S layer) of the bacterium Bacillus sphaericus NCTC 9602. The proposed model is based on the consideration of individual amino acids in the corresponding conformation of the peptide chain which additively contribute to the electronic structure of the entire protein complex. The derived results agree well with the experimental data obtained by means of photoemission (PE), resonant PE, and near-edge x-ray absorption spectroscopy.

  20. A novel fluorescent sensor protein for detecting changes in airway surface liquid glucose concentration

    PubMed Central

    Helassa, Nordine; Garnett, James P.; Farrant, Matthew; Khan, Faaizah; Pickup, John C.; Hahn, Klaus M.; MacNevin, Christopher J.; Tarran, Robert; Baines, Deborah L.

    2015-01-01

    Both lung disease and elevation of blood glucose are associated with increased glucose concentration (from 0.4 to ~4.0 mM) in the airway surface liquid (ASL). This perturbation of ASL glucose makes the airway more susceptible to infection by respiratory pathogens. ASL is minute (~1 μl/cm2) and the measurement of glucose concentration in the small volume ASL is extremely difficult. Therefore, we sought to develop a fluorescent biosensor with sufficient sensitivity to determine glucose concentrations in ASL in situ. We coupled a range of environmentally sensitive fluorophores to mutated forms of a glucose/galactose-binding protein (GBP) including H152C and H152C/A213R and determined their equilibrium binding properties. Of these, GBP H152C/A213R–BADAN (Kd 0.86 ± 0.01 mM, Fmax/F0 3.6) was optimal for glucose sensing and in ASL increased fluorescence when basolateral glucose concentration was raised from 1 to 20 mM. Moreover, interpolation of the data showed that the glucose concentration in ASL was increased, with results similar to that using glucose oxidase analysis. The fluorescence of GBP H152C/A213R–BADAN in native ASL from human airway epithelial cultures in situ was significantly increased over time when basolateral glucose was increased from 5 to 20 mM. Overall our data indicate that this GBP is a useful tool to monitor glucose homoeostasis in the lung. PMID:25220254

  1. A novel fluorescent sensor protein for detecting changes in airway surface liquid glucose concentration.

    PubMed

    Helassa, Nordine; Garnett, James P; Farrant, Matthew; Khan, Faaizah; Pickup, John C; Hahn, Klaus M; MacNevin, Christopher J; Tarran, Robert; Baines, Deborah L

    2014-12-01

    Both lung disease and elevation of blood glucose are associated with increased glucose concentration (from 0.4 to ~4.0 mM) in the airway surface liquid (ASL). This perturbation of ASL glucose makes the airway more susceptible to infection by respiratory pathogens. ASL is minute (~1 μl/cm(2)) and the measurement of glucose concentration in the small volume ASL is extremely difficult. Therefore, we sought to develop a fluorescent biosensor with sufficient sensitivity to determine glucose concentrations in ASL in situ. We coupled a range of environmentally sensitive fluorophores to mutated forms of a glucose/galactose-binding protein (GBP) including H152C and H152C/A213R and determined their equilibrium binding properties. Of these, GBP H152C/A213R-BADAN (Kd 0.86 ± 0.01 mM, Fmax/F0 3.6) was optimal for glucose sensing and in ASL increased fluorescence when basolateral glucose concentration was raised from 1 to 20 mM. Moreover, interpolation of the data showed that the glucose concentration in ASL was increased, with results similar to that using glucose oxidase analysis. The fluorescence of GBP H152C/A213R-BADAN in native ASL from human airway epithelial cultures in situ was significantly increased over time when basolateral glucose was increased from 5 to 20 mM. Overall our data indicate that this GBP is a useful tool to monitor glucose homoeostasis in the lung. PMID:25220254

  2. Regular surface layer of Azotobacter vinelandii.

    PubMed Central

    Bingle, W H; Doran, J L; Page, W J

    1984-01-01

    Washing Azotobacter vinelandii UW1 with Burk buffer or heating cells at 42 degrees C exposed a regular surface layer which was effectively visualized by freeze-etch electron microscopy. This layer was composed of tetragonally arranged subunits separated by a center-to-center spacing of approximately 10 nm. Cells washed with distilled water to remove an acidic major outer membrane protein with a molecular weight of 65,000 did not possess the regular surface layer. This protein, designated the S protein, specifically reattached to the surface of distilled-water-washed cells in the presence of the divalent calcium, magnesium, strontium, or beryllium cations. All of these cations except beryllium supported reassembly of the S protein into a regular tetragonal array. Although the surface localization of the S protein has been demonstrated, radioiodination of exposed envelope proteins in whole cells did not confirm this. The labeling behavior of the S protein could be explained on the basis of varying accessibilities of different tyrosine residues to iodination. Images PMID:6735982

  3. Resveratrol Enhances Airway Surface Liquid Depth in Sinonasal Epithelium by Increasing Cystic Fibrosis Transmembrane Conductance Regulator Open Probability

    PubMed Central

    Zhang, Shaoyan; Blount, Angela C.; McNicholas, Carmel M.; Skinner, Daniel F.; Chestnut, Michael; Kappes, John C.; Sorscher, Eric J.; Woodworth, Bradford A.

    2013-01-01

    Background Chronic rhinosinusitis engenders enormous morbidity in the general population, and is often refractory to medical intervention. Compounds that augment mucociliary clearance in airway epithelia represent a novel treatment strategy for diseases of mucus stasis. A dominant fluid and electrolyte secretory pathway in the nasal airways is governed by the cystic fibrosis transmembrane conductance regulator (CFTR). The objectives of the present study were to test resveratrol, a strong potentiator of CFTR channel open probability, in preparation for a clinical trial of mucociliary activators in human sinus disease. Methods Primary sinonasal epithelial cells, immortalized bronchoepithelial cells (wild type and F508del CFTR), and HEK293 cells expressing exogenous human CFTR were investigated by Ussing chamber as well as patch clamp technique under non-phosphorylating conditions. Effects on airway surface liquid depth were measured using confocal laser scanning microscopy. Impact on CFTR gene expression was measured by quantitative reverse transcriptase polymerase chain reaction. Results Resveratrol is a robust CFTR channel potentiator in numerous mammalian species. The compound also activated temperature corrected F508del CFTR and enhanced CFTR-dependent chloride secretion in human sinus epithelium ex vivo to an extent comparable to the recently approved CFTR potentiator, ivacaftor. Using inside out patches from apical membranes of murine cells, resveratrol stimulated an ~8 picosiemens chloride channel consistent with CFTR. This observation was confirmed in HEK293 cells expressing exogenous CFTR. Treatment of sinonasal epithelium resulted in a significant increase in airway surface liquid depth (in µm: 8.08+/-1.68 vs. 6.11+/-0.47,control,p<0.05). There was no increase CFTR mRNA. Conclusion Resveratrol is a potent chloride secretagogue from the mucosal surface of sinonasal epithelium, and hydrates airway surface liquid by increasing CFTR channel open probability

  4. Surface layer effect on nuclear deformation energy

    NASA Astrophysics Data System (ADS)

    Kolomietz, V. M.; Sanzhur, A. I.; Reznychenko, B. V.

    2016-03-01

    In this paper, we apply the direct variational method to derive the nuclear deformation energy. The extended Thomas-Fermi approximation (ETFA) for the energy functional with Skyrme forces is used. We study the influence of the finite surface layer of the nuclear density profile function on the formation of the fission barrier and the scission configuration. Comparison of the variational approach with the traditional liquid drop model (LDM) is presented. We show the sensitivity of the numerical results to the surface diffuseness parameter.

  5. 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. PMID:26808501

  6. 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

  7. Characteristics of the Martian atmosphere surface layer

    NASA Technical Reports Server (NTRS)

    Clow, G. D.; Haberle, R. M.

    1991-01-01

    Researchers extend elements of various terrestrial boundary layer models to Mars in order to estimate sensible heat, latent heat, and momentum fluxes within the Martian atmospheric surface layer. To estimate the molecular viscosity and thermal conductivity of a CO2-H2O gas mixture under Martian conditions, parameterizations were developed. Parameterizations for specific heat and and binary diffusivity were also determined. The Prandtl and Schmidt numbers derived from these thermophysical properties were found to range from 0.78 - 1.0 and 0.47 - 0.70, respectively, for Mars. Brutsaert's model for sensible and latent heat transport within the interfacial sublayer for both aerodynamically smooth and rough airflow was experimentally tested under similar conditions, validating its application to Martian conditions. For the surface sublayer, the researchers modified the definition of the Monin-Obukhov length to properly account for the buoyancy forces arising from water vapor gradients in the Martian atmospheric boundary layer. This length scale was then utilized with similarity theory turbulent flux profiles with the same form as those used by Businger et al. and others. It was found that under most Martian conditions, the interfacial and surface sublayers offer roughly comparable resistance to sensible heat and water vapor transport and are thus both important in determining the associated fluxes.

  8. Surface rheology of saponin adsorption layers.

    PubMed

    Stanimirova, R; Marinova, K; Tcholakova, S; Denkov, N D; Stoyanov, S; Pelan, E

    2011-10-18

    Extracts of the Quillaja saponaria tree contain natural surfactant molecules called saponins that very efficiently stabilize foams and emulsions. Therefore, such extracts are widely used in several technologies. In addition, saponins have demonstrated nontrivial bioactivity and are currently used as essential ingredients in vaccines, food supplements, and other health products. Previous preliminary studies showed that saponins have some peculiar surface properties, such as a very high surface modulus, that may have an important impact on the mechanisms of foam and emulsion stabilization. Here we present a detailed characterization of the main surface properties of highly purified aqueous extracts of Quillaja saponins. Surface tension isotherms showed that the purified Quillaja saponins behave as nonionic surfactants with a relatively high cmc (0.025 wt %). The saponin adsorption isotherm is described well by the Volmer equation, with an area per molecule of close to 1 nm(2). By comparing this area to the molecular dimensions, we deduce that the hydrophobic triterpenoid rings of the saponin molecules lie parallel to the air-water interface, with the hydrophilic glucoside tails protruding into the aqueous phase. Upon small deformation, the saponin adsorption layers exhibit a very high surface dilatational elasticity (280 ± 30 mN/m), a much lower shear elasticity (26 ± 15 mN/m), and a negligible true dilatational surface viscosity. The measured dilatational elasticity is in very good agreement with the theoretical predictions of the Volmer adsorption model (260 mN/m). The measured characteristic adsorption time of the saponin molecules is 4 to 5 orders of magnitude longer than that predicted theoretically for diffusion-controlled adsorption, which means that the saponin adsorption is barrier-controlled around and above the cmc. The perturbed saponin layers relax toward equilibrium in a complex manner, with several relaxation times, the longest of them being around 3

  9. Surface roughness scattering in multisubband accumulation layers

    NASA Astrophysics Data System (ADS)

    Fu, Han; Reich, K. V.; Shklovskii, B. I.

    2016-06-01

    Accumulation layers with very large concentrations of electrons where many subbands are filled became recently available due to ionic liquid and other new methods of gating. The low-temperature mobility in such layers is limited by the surface roughness scattering. However, theories of roughness scattering so far dealt only with the small-density single subband two-dimensional electron gas (2DEG). Here we develop a theory of roughness-scattering limited mobility for the multisubband large concentration case. We show that with growing 2D electron concentration n the surface dimensionless conductivity σ /(2 e2/h ) first decreases as ∝n-6 /5 and then saturates as ˜(d aB/Δ2)≫1 , where d and Δ are the characteristic length and height of the surface roughness and aB is the effective Bohr radius. This means that in spite of the shrinkage of the 2DEG thickness and the related increase of the scattering rate the 2DEG remains a good metal.

  10. Diurnal ocean surface layer model validation

    NASA Technical Reports Server (NTRS)

    Hawkins, Jeffrey D.; May, Douglas A.; Abell, Fred, Jr.

    1990-01-01

    The diurnal ocean surface layer (DOSL) model at the Fleet Numerical Oceanography Center forecasts the 24-hour change in a global sea surface temperatures (SST). Validating the DOSL model is a difficult task due to the huge areas involved and the lack of in situ measurements. Therefore, this report details the use of satellite infrared multichannel SST imagery to provide day and night SSTs that can be directly compared to DOSL products. This water-vapor-corrected imagery has the advantages of high thermal sensitivity (0.12 C), large synoptic coverage (nearly 3000 km across), and high spatial resolution that enables diurnal heating events to be readily located and mapped. Several case studies in the subtropical North Atlantic readily show that DOSL results during extreme heating periods agree very well with satellite-imagery-derived values in terms of the pattern of diurnal warming. The low wind and cloud-free conditions necessary for these events to occur lend themselves well to observation via infrared imagery. Thus, the normally cloud-limited aspects of satellite imagery do not come into play for these particular environmental conditions. The fact that the DOSL model does well in extreme events is beneficial from the standpoint that these cases can be associated with the destruction of the surface acoustic duct. This so-called afternoon effect happens as the afternoon warming of the mixed layer disrupts the sound channel and the propagation of acoustic energy.

  11. Surface Properties of PEMFC Gas Diffusion Layers

    SciTech Connect

    WoodIII, David L; Rulison, Christopher; Borup, Rodney

    2010-01-01

    The wetting properties of PEMFC Gas Diffusion Layers (GDLs) were quantified by surface characterization measurements and modeling of material properties. Single-fiber contact-angle and surface energy (both Zisman and Owens-Wendt) data of a wide spectrum of GDL types is presented to delineate the effects of hydrophobic post-processing treatments. Modeling of the basic sessile-drop contact angle demonstrates that this value only gives a fraction of the total picture of interfacial wetting physics. Polar forces are shown to contribute 10-20 less than dispersive forces to the composite wetting of GDLs. Internal water contact angles obtained from Owens-Wendt analysis were measured at 13-19 higher than their single-fiber counterparts. An inverse relationship was found between internal contact angle and both Owens-Wendt surface energy and % polarity of the GDL. The most sophisticated PEMFC mathematical models use either experimentally measured capillary pressures or the standard Young-Laplace capillary-pressure equation. Based on the results of the Owens-Wendt analysis, an advancement to the Young-Laplace equation is proposed for use in these mathematical models, which utilizes only solid surface energies and fractional surface coverage of fluoropolymer. Capillary constants for the spectrum of analyzed GDLs are presented for the same purpose.

  12. Atmospheric boundary layer over steep surface waves

    NASA Astrophysics Data System (ADS)

    Troitskaya, Yuliya; Sergeev, Daniil A.; Druzhinin, Oleg; Kandaurov, Alexander A.; Ermakova, Olga S.; Ezhova, Ekaterina V.; Esau, Igor; Zilitinkevich, Sergej

    2014-08-01

    Turbulent air-sea interactions coupled with the surface wave dynamics remain a challenging problem. The needs to include this kind of interaction into the coupled environmental, weather and climate models motivate the development of a simplified approximation of the complex and strongly nonlinear interaction processes. This study proposes a quasi-linear model of wind-wave coupling. It formulates the approach and derives the model equations. The model is verified through a set of laboratory (direct measurements of an airflow by the particle image velocimetry (PIV) technique) and numerical (a direct numerical simulation (DNS) technique) experiments. The experiments support the central model assumption that the flow velocity field averaged over an ensemble of turbulent fluctuations is smooth and does not demonstrate flow separation from the crests of the waves. The proposed quasi-linear model correctly recovers the measured characteristics of the turbulent boundary layer over the waved water surface.

  13. Thermal characteristics of the lunar surface layer.

    NASA Technical Reports Server (NTRS)

    Cremers, C. J.; Birkebak, R. C.; White, J. E.

    1972-01-01

    The thermophysical properties of the fines from the Apollo 12 landing site have been determined as a function of their relevant parameters. These properties include the thermal conductivity, thermal diffusivity, directional reflectance and emittance. The density used was the same as that observed from the returned core-tube samples and so should be close to the true density of the surface layer at the Apollo 12 site. The measured properties are used to calculate the diurnal temperature variation of the moon's surface as well as for several depths below the surface. The maximum surface of 389 K is obtained at lunar noon while the minimum temperature of 86.1 K is obtained at sunrise. It is shown that the most significant effects on temperature, as compared with previous calculations, are caused by using the directional reflectance which controls the amount of solar energy absorption during the day in place of a constant hemispherical reflectance. The results are compared with previous analyses and remote measurements.

  14. Relationship between surface tension of upper airway lining liquid and upper airway collapsibility during sleep in obstructive sleep apnea hypopnea syndrome.

    PubMed

    Kirkness, Jason P; Madronio, Melanie; Stavrinou, Rosie; Wheatley, John R; Amis, Terence C

    2003-11-01

    Lowering surface tension (gamma) of upper airway lining liquid (UAL) reduces upper airway opening (anesthetized humans) and closing (anesthetized rabbits) pressures. We now hypothesize that in sleeping obstructive sleep apnea hypopnea syndrome (OSAHS) patients lowering gamma of UAL will enhance upper airway stability and decrease the severity of sleep-disordered breathing. Nine OSAHS patients [respiratory disturbance index (RDI): 49 +/- 8 (SE) events/h, diagnostic night] participated in a two-part, one-night, polysomnography study. In the first part, upper airway closing pressures (during non-rapid eye movement sleep, Pcrit) were measured and samples of UAL (awake) were obtained before and after 2.5 ml of surfactant (Exosurf, Glaxo Smith Kline) was instilled into the posterior pharynx. The gamma of UAL was determined with the use of the "pull-off" force technique. In the second part, subjects received a second application of 2.5 ml of surfactant and then slept the remainder of the night (205 +/- 30 min). Instillation of surfactant decreased the gamma of UAL from 60.9 +/- 3.1 mN/m (control) to 45.2 +/- 2.5 mN/m (surfactant group) (n = 9, P < 0.001). Pcrit decreased from 1.19 +/- 1.14 cmH2O (control) to -0.56 +/- 1.15 cmH2O (surfactant group) (n = 7, P < 0.02). Compared with the second half of diagnostic night, surfactant decreased RDI from 51 +/- 8 to 35 +/- 8 events/h (n = 9, P < 0.03). The fall in RDI (deltaRDI) correlated with the fall in gamma of UAL (deltagamma) (deltaRDI = 1.8 x deltagamma, r = 0.68, P = 0.04). Hypopneas decreased approximately 50% from 42 +/- 8 to 20 +/- 5 events/h (n = 9, P < 0.03, paired t-test). The gamma of UAL measured the next morning remained low at 49.5 +/- 2.7 mN/m (n = 9, P < 0.001, ANOVA, compared with control). In conclusion, instillation of surfactant reduced the gamma of UAL in OSAHS patients and decreased Pcrit and the occurrence of hypopneas. Therapeutic manipulation of gamma of UAL may be beneficial in reducing the severity

  15. Surface shear stress fluctuations in the atmospheric surface layer

    NASA Astrophysics Data System (ADS)

    Monty, Jason; Hutchins, Nick; Chong, Min

    2005-11-01

    A lightweight, high frequency response (25Hz), floating element sensor was used to measure wall shear stress fluctuations in the atmospheric surface layer formed over a salt flat at the SLTEST site, Utah, USA. The sensor uses a laser position measurement system to track the motion of the floating element which consisted of a 50mm diameter foam disc, as described by Heuer & Marusic (Meas. Sci. Tech., Vol. 16, 1644- -1649, 2005). The measurements were taken as part of an internationally coordinated experimental program designed to make extensive spatial and temporal measurements of velocity, temperature and wall shear stress of the surface layer. Velocity measurements were made with both a 30m high vertical array and a 100m wide horizontal array of sonic anemometers; 18 anemometers in total were employed. Cross-correlations of shear stress and streamwise velocity fluctuations were analysed in an attempt to identify structure angles in the flow. The results were also compared with experimental data from controlled, laboratory turbulent boundary layers having three orders of magnitude lower Reynolds number.

  16. 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.

  17. Carbides composite surface layers produced by (PTA)

    SciTech Connect

    Tajoure, Meloud; Tajouri, Ali E-mail: dr.mokhtarphd@yahoo.com; Abuzriba, Mokhtar E-mail: dr.mokhtarphd@yahoo.com; Akreem, Mosbah

    2013-12-16

    The plasma transferred arc technique was applied to deposit a composite layer of nickel base with tungsten carbide in powder form on to surface of low alloy steel 18G2A type according to polish standard. Results showed that, plasma transferred arc hard facing process was successfully conducted by using Deloro alloy 22 plus tungsten carbide powders. Maximum hardness of 1489 HV and minimum dilution of 8.4 % were achieved by using an arc current of 60 A. However, when the current was further increased to 120 A and the dilution increases with current increase while the hardness decreases. Microstructure of the nickel base deposit with tungsten carbide features uniform distribution of reinforcement particles with regular grain shape half - dissolved in the matrix.

  18. Carbides composite surface layers produced by (PTA)

    NASA Astrophysics Data System (ADS)

    Tajoure, Meloud; Tajouri, Ali; Abuzriba, Mokhtar; Akreem, Mosbah

    2013-12-01

    The plasma transferred arc technique was applied to deposit a composite layer of nickel base with tungsten carbide in powder form on to surface of low alloy steel 18G2A type according to polish standard. Results showed that, plasma transferred arc hard facing process was successfully conducted by using Deloro alloy 22 plus tungsten carbide powders. Maximum hardness of 1489 HV and minimum dilution of 8.4 % were achieved by using an arc current of 60 A. However, when the current was further increased to 120 A & the dilution increases with current increase while the hardness decreases. Microstructure of the nickel base deposit with tungsten carbide features uniform distribution of reinforcement particles with regular grain shape half - dissolved in the matrix.

  19. 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

  20. 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. PMID:23757023

  1. Inhibitors of pendrin anion exchange identified in a small molecule screen increase airway surface liquid volume in cystic fibrosis.

    PubMed

    Haggie, Peter M; Phuan, Puay-Wah; Tan, Joseph-Anthony; Zlock, Lorna; Finkbeiner, Walter E; Verkman, A S

    2016-06-01

    Pendrin (SLC26A4) is a Cl(-)/anion exchanger expressed in the epithelium of inflamed airways where it is thought to facilitate Cl(-) absorption and HCO3 (-) secretion. Studies using pendrin knockout mice and airway epithelial cells from hearing-impaired subjects with pendrin loss of function suggest involvement of pendrin in inflammatory lung diseases, including cystic fibrosis (CF), perhaps by regulation of airway surface liquid (ASL) volume. Here we identified small-molecule pendrin inhibitors and demonstrated their efficacy in increasing ASL volume. A cell-based, functional high-throughput screen of ∼36,000 synthetic small molecules produced 3 chemical classes of inhibitors of human pendrin. After structure-activity studies, tetrahydropyrazolopyridine and pyrazolothiophenesulfonamide compounds reversibly inhibited pendrin-facilitated Cl(-) exchange with SCN(-), I(-), NO3 (-), and HCO3 (-) with drug concentration causing 50% inhibition down to ∼2.5 μM. In well-differentiated primary cultures of human airway epithelial cells from non-CF and CF subjects, treatment with IL-13, which causes inflammation with strong pendrin up-regulation, strongly increased Cl(-)/HCO3 (-) exchange and the increase was blocked by pendrin inhibition. Pendrin inhibition significantly increased ASL depth (by ∼8 μm) in IL-13-treated non-CF and CF cells but not in untreated cells. These studies implicate the involvement of pendrin-facilitated Cl(-)/HCO3 (-) in the regulation of ASL volume and suggest the utility of pendrin inhibitors in inflammatory lung diseases, including CF.-Haggie, P. M., Phuan, P.-W., Tan, J.-A., Zlock, L., Finkbeiner, W. E., Verkman, A. S. Inhibitors of pendrin anion exchange identified in a small molecule screen increase airway surface liquid volume in cystic fibrosis. PMID:26932931

  2. Turbulent boundary layer over porous surfaces with different surface geometries

    NASA Technical Reports Server (NTRS)

    Kong, F. Y.; Schetz, J. A.

    1982-01-01

    The turbulent boundary layer over three porous walls with different surface geometries was studied in order to investigate the individual influences of porosity and small roughness, as well as their combined effects, on turbulent boundary layer behavior. The tests were conducted in a 2 m x 2 m tunnel on a large axisymmetric model at speeds corresponding to Re(L) = 5,000,000-6,000,000. The development of the turbulent boundary layer was compared for that of sintered metal, bonded screening, and perforated sheet and then to that for the flow over a solid smooth wall and a solid, sand-roughened wall. The comparisons reveal that the effect of porosity is to shift the logarithmic region of the wall law down by a certain amount from the solid wall results and to increase the skin friction values by about 30-40%. The downward shift of the logarithmic region of the wall law and the increase of the skin friction value by the combined effects of small roughness and porosity are found to be roughly the sum of their individual effects.

  3. Automated segmentation of porcine airway wall layers using optical coherence tomography: comparison with manual segmentation and histology

    NASA Astrophysics Data System (ADS)

    Kirby, Miranda; Lee, Anthony M. D.; Candido, Tara; MacAulay, Calum; Lane, Pierre; Lam, Stephen; Coxson, Harvey O.

    2014-03-01

    The objective was to develop an automated optical coherence tomography (OCT) segmentation method. We evaluated three ex-vivo porcine airway specimens; six non-sequential OCT images were selected from each airway specimen. Histology was also performed for each airway and histology images were co-registered to OCT images for comparison. Manual segmentation of the airway luminal area, mucosa area, submucosa area and the outer airway wall area were performed for histology and OCT images. Automated segmentation of OCT images employed a despecking filter for pre-processing, a hessian-based filter for lumen and outer airway wall area segmentation, and K-means clustering for mucosa and submucosa area segmentation. Bland-Altman analysis indicated that there was very little bias between automated OCT segmentation and histology measurements for the airway lumen area (bias=-6%, 95% CI=-21%-8%), mucosa area, (bias=-4%, 95% CI=-14%-5%), submucosa area (bias=7%, 95% CI=-7%-20%) and outer airway wall area segmentation results (bias=-5%, 95% CI=-14%-5%). We also compared automated and manual OCT segmentation and Bland-Altman analysis indicated that there was negligible bias between luminal area (bias=4%, 95% CI=1%-8%), mucosa area (bias=-3%, 95% CI=-6%-1%), submucosa area (bias=-2%, 95% CI=-10%-6%) and the outer airway wall (bias=-3%, 95% CI=-13%-6%). The automated segmentation method for OCT airway imaging developed here allows for accurate and precise segmentation of the airway wall components, suggesting that translation of this method to in vivo human airway analysis would allow for longitudinal and serial studies.

  4. Surface Layer Turbulence During a Frontal Passage

    SciTech Connect

    Piper, M; Lundquist, J K

    2004-06-15

    Some recent investigations have begun to quantify turbulence and dissipation in frontal zones to address the question of what physical mechanism counteracts the intensification of temperature and velocity gradients across a developing front. Frank (1994) examines the turbulence structure of two fronts that passed a 200m instrumented tower near Karlsruhe, Germany. In addition to showing the mean vertical structure of the fronts as they pass the tower, Frank demonstrates that there is an order of magnitude or more increase in turbulent kinetic energy across the frontal zone. Blumen and Piper (1999) reported turbulence statistics, including dissipation rate measurements, from the MICROFRONTS field experiment, where high-frequency turbulence data were collected from tower-mounted hotwire and sonic anemometers in a cold front and in a density current. Chapman and Browning (2001) measured dissipation rate in a precipitating frontal zone with high-resolution Doppler radar. Their measurements were conducted above the surface layer, to heights of 5km. The dissipation rate values they found are comparable to those measured in Kennedy and Shapiro (1975) in an upper-level front. Here, we expand on these recent studies by depicting the behavior of the fine scales of turbulence near the surface in a frontal zone. The primary objective of this study is to quantify the levels of turbulence and dissipation occurring in a frontal zone through the calculation of kinetic energy spectra and dissipation rates. The high-resolution turbulence data used in this study are taken during the cold front that passed the MICROFRONTS site in the early evening hours of 20 March 1995. These new measurements can be used as a basis for parameterizing the effects of surface-layer turbulence in numerical models of frontogenesis. We present three techniques for calculating the dissipation rate: direct dissipation technique, inertial dissipation technique and Kolmogorov's four-fifths law. Dissipation rate

  5. A model of surfactant-induced surface tension effects on the parenchymal tethering of pulmonary airways.

    PubMed

    Fujioka, Hideki; Halpern, David; Gaver, Donald P

    2013-01-18

    We developed a computational model of lung parenchyma, which is comprised of individual alveolar chamber models. Each alveolus is modeled by a truncated octahedron. Considering the force balance between the elastin and collagen fibers laying on the alveolar membrane and the pressures acting on the membrane, we computed the deformations of the parenchyma with a finite element method. We focused on the effect of surfactant on the force of parenchymal tethering an airway. As the lung inflates, the parenchyma becomes stiffer and the tethering force becomes stronger. As the alveolar surfactant concentration is reduced, the lung volume at a fixed alveolar pressure decreases, and thus, the tethering force becomes weaker. The distortion of parenchyma caused by the deformation of an airway extends widely around the airway. The displacement of parenchyma decays with distance from the airway wall, but deviates from the prediction based on a theory for a continuum material. Using results obtained from the present lung parenchyma model, we also developed a simple 1-dimensional model for parenchyma tethering force on an airway, which could be utilized for the analysis of liquid/gas transports in an axis-symmetric elastic airway. The effective shear modulus was calculated from the pressure-volume relation of parenchyma. By manipulating the pressure-volume curve, this simple model may be used to predict the parenchyma tethering force in diseased lungs. PMID:23235110

  6. 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. PMID:25665521

  7. Neutral surface layer turbulence over complex terrain

    SciTech Connect

    Bowen, B.M.

    1995-09-01

    Accurate turbulence estimates are important input to atmospheric dispersion models since they characterize downwind dispersion and hence, potential pollutant concentrations. When only basic wind information is available, an atmospheric modeler must first estimate roughness length (z{sub 0},) at the location of interest, ({mu}*) from similarity theory using average wind speed ({mu}) and z{sub 0}, and finally apply experimentally derived relationships to determine the turbulence intensities. Even when turbulence coefficients are measured, the turbulence profile must be estimated in the surface layer, using, for example, the power law recommended in a US Environmental Protection Agency guidance document. In this study, turbulent intensities and wind profiles are analyzed in eight direction sectors during near neutral stability. ``Local`` and ``regional`` roughness lengths are calculated from wind speed profiles and from longitudinal turbulence intensities ({sigma}{sub {mu}}) at both sites. With ``regional`` roughness length, complex terrain features are in effect the roughness elements. Profiles of median, 15-minute averaged turbulence intensities {sigma}{sub {mu}}, {sigma}{sub {nu}} and {sigma}{sub w} are calculated at both sites. Profiles of median {sigma}{sub {theta}} and {sigma}{sub {phi}} are also calculated using four mean values of regional z{sub 0} at both sites. Finally, differences between widely-used turbulence relationships and the relationships determined in this study, and their possible effect on model results, are discussed.

  8. A Turbulent Boundary Layer over Superhydrophobic Surfaces

    NASA Astrophysics Data System (ADS)

    Park, Hyunwook; Kim, John

    2015-11-01

    Direct numerical simulations of a spatially developing turbulent boundary layer (TBL) developing over superhydrophobic surfaces (SHS) were performed in order to investigate the underlying physics of turbulent flow over SHS. SHS were modeled through the shear-free boundary condition, assuming that the gas-liquid interfaces remained as non-deformable. Pattern-averaged turbulence statistics were examined in order to determine the effects of SHS on turbulence in no-slip and slip regions separately. Near-wall turbulence over the slip region was significantly affected by SHS due to insufficient mean shear required to sustain near-wall turbulence. SHS also indirectly affected near-wall turbulence over the no-slip region. In addition to the effects of the spanwise width of SHS on skin-friction drag reduction reported previously, spatial effects in the streamwise direction were examined. A guideline for optimal design of SHS geometry will be discussed. This research was supported by the ONR (Grant No. N000141410291).

  9. Acute exposure to silica nanoparticles aggravate airway inflammation: different effects according to surface characteristics

    PubMed Central

    Park, Hye Jung; Sohn, Jung-Ho; Kim, Yoon-Ju; Park, Yoon Hee; Han, Heejae; Park, Kyung Hee; Lee, Kangtaek; Choi, Hoon; Um, Kiju; Choi, In-Hong; Park, Jung-Won; Lee, Jae-Hyun

    2015-01-01

    Silica nanoparticles (SNPs) are widely used in many scientific and industrial fields despite the lack of proper evaluation of their potential toxicity. This study examined the effects of acute exposure to SNPs, either alone or in conjunction with ovalbumin (OVA), by studying the respiratory systems in exposed mouse models. Three types of SNPs were used: spherical SNPs (S-SNPs), mesoporous SNPs (M-SNPs), and PEGylated SNPs (P-SNPs). In the acute SNP exposure model performed, 6-week-old BALB/c female mice were intranasally inoculated with SNPs for 3 consecutive days. In the OVA/SNPs asthma model, the mice were sensitized two times via the peritoneal route with OVA. Additionally, the mice endured OVA with or without SNP challenges intranasally. Acute SNP exposure induced significant airway inflammation and airway hyper-responsiveness, particularly in the S-SNP group. In OVA/SNPs asthma models, OVA with SNP-treated group showed significant airway inflammation, more than those treated with only OVA and without SNPs. In these models, the P-SNP group induced lower levels of inflammation on airways than both the S-SNP or M-SNP groups. Interleukin (IL)-5, IL-13, IL-1β and interferon-γ levels correlated with airway inflammation in the tested models, without statistical significance. In the mouse models studied, increased airway inflammation was associated with acute SNPs exposure, whether exposed solely to SNPs or SNPs in conjunction with OVA. P-SNPs appear to be relatively safer for clinical use than S-SNPs and M-SNPs, as determined by lower observed toxicity and airway system inflammation. PMID:26183169

  10. Mechanisms of surface-tension-induced epithelial cell damage in a model of pulmonary airway reopening.

    PubMed

    Bilek, Anastacia M; Dee, Kay C; Gaver, Donald P

    2003-02-01

    Airway collapse and reopening due to mechanical ventilation exerts mechanical stress on airway walls and injures surfactant-compromised lungs. The reopening of a collapsed airway was modeled experimentally and computationally by the progression of a semi-infinite bubble in a narrow fluid-occluded channel. The extent of injury caused by bubble progression to pulmonary epithelial cells lining the channel was evaluated. Counterintuitively, cell damage increased with decreasing opening velocity. The presence of pulmonary surfactant, Infasurf, completely abated the injury. These results support the hypotheses that mechanical stresses associated with airway reopening injure pulmonary epithelial cells and that pulmonary surfactant protects the epithelium from this injury. Computational simulations identified the magnitudes of components of the stress cycle associated with airway reopening (shear stress, pressure, shear stress gradient, or pressure gradient) that may be injurious to the epithelial cells. By comparing these magnitudes to the observed damage, we conclude that the steep pressure gradient near the bubble front was the most likely cause of the observed cellular damage. PMID:12433851

  11. Layers of Porous Superhydrophobic Surfaces for Robust Water Repellency

    NASA Astrophysics Data System (ADS)

    Ahmadi, Farzad; Boreyko, Jonathan; Nature-Inspired Fluids; Interfaces Team

    2015-11-01

    In nature, birds exhibit multiple layers of superhydrophobic feathers that repel water. Inspired by bird feathers, we utilize porous superhydrophobic surfaces and compare the wetting and dewetting characteristics of a single surface to stacks of multiple surfaces. The superhydrophobic surfaces were submerged in water in a closed chamber. Pressurized gas was regulated to measure the critical pressure for the water to fully penetrate through the surfaces. In addition to using duck feathers, two-tier porous superhydrophobic surfaces were fabricated to serve as synthetic mimics with a controlled surface structure. The energy barrier for the wetting transition was modeled as a function of the number of layers and their orientations with respect to each other. Moreover, after partial impalement into a subset of the superhydrophobic layers, it was observed that a full dewetting transition was possible, which suggests that natural organisms can exploit their multiple layers to prevent irreversible wetting.

  12. 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...

  13. 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...

  14. Effects of acid aerosol exposure on the surface properties of airway mucus

    SciTech Connect

    Lee, M.M.; Schuerch, S.; Roth, S.H.

    1995-12-31

    It was hypothesized that the mucous layer lining the tracheas of rats and guinea pigs contains surfactant material capable of lowering the air/mucus surface tension, {gamma}, and that exposure to an irritant aerosol would raise the {gamma}. The {gamma} of the surface film was measured directly by a spreading droplet technique and indirectly by displacement of polymethyl methacrylate particles into the aqueous layer. The morphology of the mucous film was examined by electron microscopy after nonaqueous fixation. {gamma} was 33.3 {plus_minus} 0.70 (SE) mN/m and 32.3 {plus_minus} 0.68 (SE) mN/m for the normal rat and guinea pig trachea, respectively. Exposure for 4 h to aerosols of sulfuric acid (94.1 {plus_minus} 18.68 (SD) and 43.3 {plus_minus} 4.57 (SD) mg/m{sup 3}) caused a several-fold increase in thickness of the mucous layer with exudation of protein-like material. The osmiophilic surfactant film at the air/mucus interface became irregularly thickened and multilayered. Despite these morphological changes {gamma} remained low, 33.2 {plus_minus} 0.43 (SE) mN/m and 32.6 {plus_minus} 0.60 (SE) mN/m for rats and guinea pigs, respectively, and displacement of particles into the subphase was not compromised. The results indicate that rodent tracheas are able to maintain a low surface tension in the presence of injury. 24 refs., 9 figs.

  15. Modeling of turbulent transport in the surface layer

    NASA Technical Reports Server (NTRS)

    Smith, G. L.

    1973-01-01

    The turbulence equations as written by Donaldson using the method of invariant modeling have been applied to the following limiting cases of the surface or constant flux layer of the planetary boundary layer: (1) Neutrally stable; (2) stable (above influence of surface roughness); (3) nearly neutrally stable; and (4) very unstable (free convection). For the neutrally stable case, the equations are shown to admit as a solution the familiar logarithmic profile. By use of this result, boundary conditions suitable for the surface layer are defined and are simple to apply to rough surfaces.

  16. ac conductance of surface layer in lithium tetraborate single crystals

    NASA Astrophysics Data System (ADS)

    Kim, Chung-Sik; Park, Jong-Ho; Moon, Byung Kee; Seo, Hyo-Jin; Choi, Byung-Chun; Hwang, Yoon-Hwae; Kim, Hyung Kook; Kim, Jung Nam

    2003-12-01

    ac conductance for the electrode effect in Li2B4O7 single crystal was investigated by use of a coplanar electrode applied on the surface of a (001) plate. A coplanar electrode in this material more clearly shows conduction of the electrode effect than a conventional parallel planar electrode. The electrode effect in ac conductance is likely to be controlled by the surface layer, which is a poorly conductive depletion layer possibly filled with vacancies of lithium ions. We found that the surface layer is not locally distributed near the electrodes, but, rather, on the broad area of the surface (001) plane of the material. So we conclude that the electrode effect in ac conduction of Li2B4O7 single crystal is mainly due to the poor conductive surface layer distributed over the whole surface of the (001) plane and is not a secondary phase formed by reaction with the electrode material.

  17. Equilibrium of wetting layers on rough surfaces

    NASA Astrophysics Data System (ADS)

    Liu, Kuang-Yu

    The objective of this dissertation is to study physical adsorption on solids with complex surface geometry--especially on self-similar and self-affine fractal surfaces--in the context of three phase equilibria. Such studies will facilitate the prediction of the adsorbed film from known surface properties, e.g., topography or interactions (direct problem), and the inference of unknown surface properties from experimental data (inverse problem). These results will then be compared against wetting phenomena on planar surfaces and with other methods of probing complex surface geometries of solids. Chapter One offers the basic context, including wetting phenomena on planar surfaces, the cornerstone prediction of wetting transition on planar surfaces by Cahn, the concepts of fractal geometry, and the formation of fractal objects, for later comparison. The rest of this dissertation will be devoted to the study of multilayer adsorption on fractal surfaces. When a liquid film completely wets the surface, the number of adsorbed molecules as a function of the vapor pressure will depend strongly on the underlying surface geometry. The fractal structure leads to the Frenkel-Halsey-Hill type isotherms with the exponents in the corresponding power laws depending on the fractal dimension and on whether the dominant influence is from the substrate potential (van der Waals wetting) or from the film-vapor surface tension (capillary wetting). The transition between the two is the analog of Cahn's transition: The thermal disorder is replaced by the quenched disorder. This analogy is studied in Chapter Two for self-similar surfaces, and in Chapter Four for self-affine surfaces. In Chapter Two the derivation framework also automatically identifies well-defined coexistence lines in the pressure-dimension diagram. The effect of the repulsive part is examined there too. A simple analysis of adsorption/desorption hysteresis on self-similar surfaces in Chapter Three concludes that the

  18. Surface and interface properties of thin pentacene and parylene layers

    NASA Astrophysics Data System (ADS)

    Vincze, Andrej; Jakabovič, Ján; Srnánek, Rudolf; Šatka, Alexander; Kováč, Jaroslav; Kováč, Jaroslav

    2009-06-01

    To improve Organic Thin Film Transistor (OTFT) properties we study OTFT semiconductor/dielectric interfacial properties via examination of the gate dielectric using thin Parylene C layer. Structural and morphology properties of pentacene layers deposited on parylene layer and SiO2/Si substrate structure were compared. The surface morphology was investigated using atomic force microscopy (AFM) and scanning electron microscopy (SEM). AFM topography of pentacene layer in non-contact mode confirmed the preferable pentacene grain formation on parylene surface in dependence on layer thickness. The distribution of chemical species on the surfaces and composition depth profiles were measured by secondary ion mass spectroscopy (SIMS) and surface imaging. The depth profiles of the analyzed structures show a homogenous pentacene layer, characterized with C or C2 ions. Relatively sharp interface between pentacene and parylene layers was estimated by characteristic increased intensity of CCl ions peak. For revealing the pentacene phases in the structures the Micro-Raman spectroscopy was utilized. Conformal coatings of parylene and pentacene layers without pinholes resulted from the deposition process as was confirmed by SIMS surface imaging. For the pentacene layers thicker than 20 nm, both thin and bulk pentacene phases were detected by Micro-Raman spectroscopy, while for the pentacene layer thickness of 5 and 10 nm the preferable thin phase was detected. The complete characterisation of pentacene layers deposited on SiO2 and parylene surface revealed that the formation of large grains suggests 3D pentacene growth at parylene layer with small voids between grains and more than one monolayer step growth. The results will be utilized for optimization of the deposition process.

  19. Preservation of Archaeal Surface Layer Structure During Mineralization

    PubMed Central

    Kish, Adrienne; Miot, Jennyfer; Lombard, Carine; Guigner, Jean-Michel; Bernard, Sylvain; Zirah, Séverine; Guyot, François

    2016-01-01

    Proteinaceous surface layers (S-layers) are highly ordered, crystalline structures commonly found in prokaryotic cell envelopes that augment their structural stability and modify interactions with metals in the environment. While mineral formation associated with S-layers has previously been noted, the mechanisms were unconstrained. Using Sulfolobus acidocaldarius a hyperthermophilic archaeon native to metal-enriched environments and possessing a cell envelope composed only of a S-layer and a lipid cell membrane, we describe a passive process of iron phosphate nucleation and growth within the S-layer of cells and cell-free S-layer “ghosts” during incubation in a Fe-rich medium, independently of metabolic activity. This process followed five steps: (1) initial formation of mineral patches associated with S-layer; (2) patch expansion; (3) patch connection; (4) formation of a continuous mineral encrusted layer at the cell surface; (5) early stages of S-layer fossilization via growth of the extracellular mineralized layer and the mineralization of cytosolic face of the cell membrane. At more advanced stages of encrustation, encrusted outer membrane vesicles are formed, likely in an attempt to remove damaged S-layer proteins. The S-layer structure remains strikingly well preserved even upon the final step of encrustation, offering potential biosignatures to be looked for in the fossil record. PMID:27221593

  20. Preservation of Archaeal Surface Layer Structure During Mineralization.

    PubMed

    Kish, Adrienne; Miot, Jennyfer; Lombard, Carine; Guigner, Jean-Michel; Bernard, Sylvain; Zirah, Séverine; Guyot, François

    2016-01-01

    Proteinaceous surface layers (S-layers) are highly ordered, crystalline structures commonly found in prokaryotic cell envelopes that augment their structural stability and modify interactions with metals in the environment. While mineral formation associated with S-layers has previously been noted, the mechanisms were unconstrained. Using Sulfolobus acidocaldarius a hyperthermophilic archaeon native to metal-enriched environments and possessing a cell envelope composed only of a S-layer and a lipid cell membrane, we describe a passive process of iron phosphate nucleation and growth within the S-layer of cells and cell-free S-layer "ghosts" during incubation in a Fe-rich medium, independently of metabolic activity. This process followed five steps: (1) initial formation of mineral patches associated with S-layer; (2) patch expansion; (3) patch connection; (4) formation of a continuous mineral encrusted layer at the cell surface; (5) early stages of S-layer fossilization via growth of the extracellular mineralized layer and the mineralization of cytosolic face of the cell membrane. At more advanced stages of encrustation, encrusted outer membrane vesicles are formed, likely in an attempt to remove damaged S-layer proteins. The S-layer structure remains strikingly well preserved even upon the final step of encrustation, offering potential biosignatures to be looked for in the fossil record. PMID:27221593

  1. Effect of modifying quantum dot surface charge on airway epithelial cell uptake in vitro

    PubMed Central

    Chau, Eric; Galloway, Justin F.; Nelson, Antoinette; Breysse, Patrick N.; Wirtz, Denis; Searson, Peter C.

    2012-01-01

    The respiratory system is one of the portals of entry into the body, and hence inhalation of engineered nanomaterials is an important route of exposure. The broad range of physicochemical properties that influence biological responses necessitate the systematic study to contribute to understanding occupational exposure. Here, we report on the influence of nanoparticle charge and dose on human airway epithelial cells, and show that this platform can be used to evaluate consequences of exposure to engineered nanomaterials. PMID:22783847

  2. TEM studies of the nitrided Ni-Ti surface layer.

    PubMed

    Lelatko, J; Paczkowski, P; Wierzchoń, T; Morawiec, H

    2006-09-01

    The structure of surface layer, obtained on the nearly equiatomic Ni-Ti alloy after nitriding under glow discharge conditions at temperatures 700 or 800 degrees C, was investigated. The structural characterization of the intruded layer was performed on cross-sectional thin foils by the use of the transmission and scanning electron microscopes. The obtained results show that the nitrided layers consist mainly of the nanocrystalline TiN phase and small amount of Ti(2)N. Between the nitrided layers and beta-NiTi matrix an intermediate Ti(2)Ni phase layer was observed. PMID:17059538

  3. 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

  4. Generation and characterization of surface layers on acoustically levitated drops.

    PubMed

    Tuckermann, Rudolf; Bauerecker, Sigurd; Cammenga, Heiko K

    2007-06-15

    Surface layers of natural and technical amphiphiles, e.g., octadecanol, stearic acid and related compounds as well as perfluorinated fatty alcohols (PFA), have been investigated on the surface of acoustically levitated drops. In contrast to Langmuir troughs, traditionally used in the research of surface layers at the air-water interface, acoustic levitation offers the advantages of a minimized and contact-less technique. Although the film pressure cannot be directly adjusted on acoustically levitated drops, it runs through a wide pressure range due to the shrinking surface of an evaporating drop. During this process, different states of the generated surface layer have been identified, in particular the phase transition from the gaseous or liquid-expanded to the liquid-condensed state of surface layers of octadecanol and other related amphiphiles. Characteristic parameters, such as the relative permeation resistance and the area per molecule in a condensed surface layer, have been quantified and were found comparable to results obtained from surface layers generated on Langmuir troughs. PMID:17376468

  5. Observation of Surface Layering in a Nonmetallic Liquid

    SciTech Connect

    Mo,H.; Evmenenko, G.; Kewalramani, S.; Kim, K.; Ehrlich, S.; Dutta, P.

    2006-01-01

    Oscillatory density profiles (layers) have previously been observed at the free surfaces of liquid metals but not in other isotropic liquids. We have used x-ray reflectivity to study a molecular liquid, tetrakis(2-ethylhexoxy)silane. When cooled to T/T{sub c}{approx}0.25 (well above the freezing point for this liquid), density oscillations appear at the surface. Lateral order within the layers is liquidlike. Our results confirm theoretical predictions that a surface-layered state will appear even in dielectric liquids at sufficiently low temperatures, if not preempted by freezing.

  6. Improve oxidation resistance at high temperature by nanocrystalline surface layer.

    PubMed

    Xia, Z X; Zhang, C; Huang, X F; Liu, W B; Yang, Z G

    2015-01-01

    An interesting change of scale sequence occurred during oxidation of nanocrystalline surface layer by means of a surface mechanical attrition treatment. The three-layer oxide structure from the surface towards the matrix is Fe3O4, spinel FeCr2O4 and corundum (Fe,Cr)2O3, which is different from the typical two-layer scale consisted of an Fe3O4 outer layer and an FeCr2O4 inner layer in conventional P91 steel. The diffusivity of Cr, Fe and O is enhanced concurrently in the nanocrystalline surface layer, which causes the fast oxidation in the initial oxidation stage. The formation of (Fe,Cr)2O3 inner layer would inhabit fast diffusion of alloy elements in the nanocrystalline surface layer of P91 steel in the later oxidation stage, and it causes a decrease in the parabolic oxidation rate compared with conventional specimens. This study provides a novel approach to improve the oxidation resistance of heat resistant steel without changing its Cr content. PMID:26269034

  7. Improve oxidation resistance at high temperature by nanocrystalline surface layer

    NASA Astrophysics Data System (ADS)

    Xia, Z. X.; Zhang, C.; Huang, X. F.; Liu, W. B.; Yang, Z. G.

    2015-08-01

    An interesting change of scale sequence occurred during oxidation of nanocrystalline surface layer by means of a surface mechanical attrition treatment. The three-layer oxide structure from the surface towards the matrix is Fe3O4, spinel FeCr2O4 and corundum (Fe,Cr)2O3, which is different from the typical two-layer scale consisted of an Fe3O4 outer layer and an FeCr2O4 inner layer in conventional P91 steel. The diffusivity of Cr, Fe and O is enhanced concurrently in the nanocrystalline surface layer, which causes the fast oxidation in the initial oxidation stage. The formation of (Fe,Cr)2O3 inner layer would inhabit fast diffusion of alloy elements in the nanocrystalline surface layer of P91 steel in the later oxidation stage, and it causes a decrease in the parabolic oxidation rate compared with conventional specimens. This study provides a novel approach to improve the oxidation resistance of heat resistant steel without changing its Cr content.

  8. Improve oxidation resistance at high temperature by nanocrystalline surface layer

    PubMed Central

    Xia, Z. X.; Zhang, C.; Huang, X. F.; Liu, W. B.; Yang, Z. G.

    2015-01-01

    An interesting change of scale sequence occurred during oxidation of nanocrystalline surface layer by means of a surface mechanical attrition treatment. The three-layer oxide structure from the surface towards the matrix is Fe3O4, spinel FeCr2O4 and corundum (Fe,Cr)2O3, which is different from the typical two-layer scale consisted of an Fe3O4 outer layer and an FeCr2O4 inner layer in conventional P91 steel. The diffusivity of Cr, Fe and O is enhanced concurrently in the nanocrystalline surface layer, which causes the fast oxidation in the initial oxidation stage. The formation of (Fe,Cr)2O3 inner layer would inhabit fast diffusion of alloy elements in the nanocrystalline surface layer of P91 steel in the later oxidation stage, and it causes a decrease in the parabolic oxidation rate compared with conventional specimens. This study provides a novel approach to improve the oxidation resistance of heat resistant steel without changing its Cr content. PMID:26269034

  9. Dry deposition of pollutant and marker particles onto live mouse airway surfaces enhances monitoring of individual particle mucociliary transit behaviour.

    PubMed

    Donnelley, Martin; Morgan, Kaye S; Siu, Karen K W; Parsons, David W

    2012-07-01

    Particles suspended in the air are inhaled during normal respiration and unless cleared by airway defences, such as the mucociliary transit (MCT) system, they can remain and affect lung and airway health. Synchrotron phase-contrast X-ray imaging (PCXI) methods have been developed to non-invasively monitor the behaviour of individual particles in live mouse airways and in previous studies the MCT behaviour of particles and fibres in the airways of live mice after deposition in a saline carrier fluid have been examined. In this study a range of common respirable pollutant particles (lead dust, quarry dust and fibreglass fibres) as well as marker particles (hollow glass micro-spheres) were delivered into the trachea of live mice using a dry powder insufflator to more accurately mimic normal environmental particulate exposure and deposition via inhalation. The behaviour of the particles once delivered onto the airway surface was tracked over a five minute period via PCXI. All particles were visible after deposition. Fibreglass fibres remained stationary throughout while all other particle types transited the tracheal surface throughout the imaging period. In all cases the majority of the particle deposition and any airway surface activity was located close to the dorsal tracheal wall. Both the individual and bulk motions of the glass bead marker particles were visible and their behaviour enabled otherwise hidden MCT patterns to be revealed. This study verified the value of PCXI for examining the post-deposition particulate MCT behaviour in the mouse trachea and highlighted that MCT is not a uniform process as suggested by radiolabel studies. It also directly revealed the advantages of dry particle delivery for establishing adequate particulate presence for visualizing MCT behaviour. The MCT behaviour and rate seen after dry particle delivery was different from that in previous carrier-fluid studies. It is proposed that dry particle delivery is essential for producing

  10. Process Conditions of Forming the Surface Layer of Aluminum Powder Product by Layer-by-layer Laser Sintering

    NASA Astrophysics Data System (ADS)

    Saprykina, N. A.; Saprykin, A. A.; Ibragimov, E. A.; Arkhipova, D. A.

    2016-07-01

    The paper presents data on state of the art in selective laser sintering of products. Layer-by-layer sintering is shown to be a future-oriented technology, making it possible to synthesize products of metal powder materials. Factors, influencing the quality of a sintered product, are revealed in the paper. It presents outcomes of experiments, focused on the dependence of surface layer thickness of sintered aluminum powder PA-4 on laser processing conditions. Basic factors, influencing the quality of a sintered surface layer include laser power, speeds of scanning and moving the laser beam on the layer of powder. Thickness of the sintered layer varies from 0.74 to 1.55 mm, as the result of changing the laser processing conditions.

  11. Thin gold layer in Ni electroforming process: optical surface characterization

    NASA Astrophysics Data System (ADS)

    Sironi, G.; Spiga, D.; Pareschi, G.; Missaglia, N.; Paganini, L.

    2009-08-01

    Mandrel replication by Nickel electroforming is a well-suited process to manufacture X-ray mirrors, making use of Gold layer playing the twofold role of release agent and reflective coating. To increase the optical performances of mirrors it is crucial to minimize the impact of X-ray scattering effects related to surface microroughness, especially when the mirror is intended to operate in hard X-rays. In this case, the Gold layer simply acts as release agent because the reflection is demanded to interferential over-coatings. Even though the replicated optical surface is usually believed to reproduce the smooth topography of the master, a surface degradation is commonly observed. Such a worsening can also suffer from a contribution from the spontaneous roughness growth of the Gold layer itself: if this is the case, the mirror's optical quality could potentially benefit from the utilization of a thin Gold layer (< 100 nm) instead of the traditional thick gold layer (> 100 nm). To prove the effectiveness of the Gold thickness reduction, a microroughness characterization of replicated thin gold layers has been achieved. We report here a preliminary roughness study of 3 electroformed Ni samples replicated from a super-polished Zerodur flat master with various Gold layer thicknesses, in the spectral range 0.02-1000 μm. The study is organized as follows: (a) characterization of the 3 replicated samples; (b) comparison of the Gold roughness for thin vs. thick layers; (c) comparison of the two sides of Gold layers.

  12. Subgrid-scale Modeling in the Atmospheric Surface Layer^1

    NASA Astrophysics Data System (ADS)

    Khanna, S.; Wyngaard, J. C.; Brasseur, J. G.

    1996-11-01

    Subgrid-scale (SGS) modeling is crucial in the surface layer of wall-bounded flows where the vertical velocity fluctuations cannot be well resolved. We focus on the distinct characteristics of the surface layer of the atmospheric boundary layer (ABL), and analyze, from a highly resolved surface-layer field of a moderately convective ABL, the extent to which Smagorinsky-based SGS models predict these characteristics. The fields were generated using a nested-mesh large-eddy simulation (LES) with the finest mesh having an effective grid resolution of 512^3 covering 1/16^th of the boundary-layer depth. At a height where the fine mesh resolves 90 % of the total fluxes and variances, the resolved fields were treated as surrogate fully resolved fields that were filtered onto a coarser mesh to get ``resolvable'' and ``subgrid'' fields. Preliminary results show that Smagorinsky-based models fail to capture many of the distinctive characteristics of the ABL surface layer. For example, they do not capture the anisotropic distribution of subgrid-scale energy among the horizontal and the vertical components, and they grossly underestimate the SGS horizontal temperature flux. Currently we are focusing on more suitable closures for the atmospheric surface layer. A DNS-based study is also underway and will be used to supplement this analysis. ^1 supported by ARO (# DAAL03-92-G-0117) and ONR (# N00014-92-J-1688)

  13. Turbulent boundary layer on a convex, curved surface

    NASA Technical Reports Server (NTRS)

    Gillis, J. C.; Johnston, J. P.; Kays, W. M.; Moffat, R. J.

    1980-01-01

    The effects of strong convex curvature on boundary layer turbulence were investigated. The data gathered on the behavior of Reynolds stress suggested the formulation of a simple turbulence model. Three sets of data were taken on two separate facilities. Both rigs had flow from a flat surface, over a convex surface with 90 deg of turning, and then onto a flat recovery surface. The geometry was adjusted so that, for both rigs, the pressure gradient along the test surface was zero - thus avoiding any effects of streamwise acceleration on the wall layers. Results show that after a sudden introduction of curvature, the shear stress in the outer part of the boundary layer is sharply diminished and is even slightly negative near the edge. The wall shear also drops off quickly downstream. In contrast, when the surface suddenly becomes flat again, the wall shear and shear stress profiles recover very slowly towards flat wall conditions.

  14. Nanoshells made easy: improving Au layer growth on nanoparticle surfaces.

    PubMed

    Brinson, Bruce E; Lassiter, J Britt; Levin, Carly S; Bardhan, Rizia; Mirin, Nikolay; Halas, Naomi J

    2008-12-16

    The growth of a continuous, uniform Au layer on a dielectric nanoparticle is the critical step in the synthesis of nanoparticles such as nanoshells or nanorice, giving rise to their unique geometry-dependent plasmon resonant properties. Here, we report a novel, streamlined method for Au layer metallization on prepared nanoparticle surfaces using carbon monoxide as the reducing agent. This approach consistently yields plasmonic nanoparticles with highly regular shell layers and is immune to variations in precursor or reagent preparation. Single particle spectroscopy combined with scanning electron microscopy reveal that thinner, more uniform shell layers with correspondingly red-shifted optical resonances are achievable with this approach. PMID:19360963

  15. Dusty boundary layer in a surface-burst explosion

    SciTech Connect

    Kuhl, A.L.; Ferguson, R.E.; Chien, K.Y.; Collins, J.P.

    1993-08-01

    Dusty boundary layers are an inherent feature of explosions over ground surfaces. Detailed knowledge of dusty boundary layer characteristics is needed in explosion safety analysis (e.g., to calculate the drag loads on structures). Also, to predicct the amount of dust in the rising fireball of an explsion, one must know the dusty boundary layer swept up during the positive and negative phases of the blast wave and how much of this boundary layer dust is entrained into the stem of the dust cloud. This paper describes the results of numerical simulations of the dusty boundary layer created by a surface burst explosion. The evolution of the flow was calculated by a high-order Godunov code that solves the nonsteady conservation laws.

  16. Thermocapillary convection in two immiscible liquid layers with free surface

    NASA Technical Reports Server (NTRS)

    Doi, Takao; Koster, Jean N.

    1993-01-01

    Thermocapillary convection is studied in two immiscible liquid layers with one free surface, one liquid/liquid interface, and differential heating applied parallel to the interfaces. An analytical solution is introduced for infinite horizontal layers. The defining parameter for the flow pattern is lambda, the ratio of the temperature coefficient of the interfacial tension to that of the surface tension. Four different flow patterns exist under zero gravity conditions. 'Halt' conditions which halt the fluid motion in the lower encapsulated liquid layer have been found. A numerical experiment is carried out to study effects of vertical end walls on the double layer convection in a 2D cavity. The halt condition obtained from the analytical study is found to be valid in the limit of small Reynolds numbers. The flow in the encapsulated liquid layer can be suppressed substantially.

  17. Surgical Airway

    PubMed Central

    Patel, Sapna A; Meyer, Tanya K

    2014-01-01

    Close to 3% of all intubation attempts are considered difficult airways, for which a plan for a surgical airway should be considered. Our article provides an overview of the different types of surgical airways. This article provides a comprehensive review of the main types of surgical airways, relevant anatomy, necessary equipment, indications and contraindications, preparation and positioning, technique, complications, and tips for management. It is important to remember that the placement of a surgical airway is a lifesaving procedure and should be considered in any setting when one “cannot intubate, cannot ventilate”. PMID:24741501

  18. Boundary Layer Flow Over a Moving Wavy Surface

    NASA Astrophysics Data System (ADS)

    Hendin, Gali; Toledo, Yaron

    2016-04-01

    Boundary Layer Flow Over a Moving Wavy Surface Gali Hendin(1), Yaron Toledo(1) January 13, 2016 (1)School of Mechanical Engineering, Tel-Aviv University, Israel Understanding the boundary layer flow over surface gravity waves is of great importance as various atmosphere-ocean processes are essentially coupled through these waves. Nevertheless, there are still significant gaps in our understanding of this complex flow behaviour. The present work investigates the fundamentals of the boundary layer air flow over progressive, small-amplitude waves. It aims to extend the well-known Blasius solution for a boundary layer over a flat plate to one over a moving wavy surface. The current analysis pro- claims the importance of the small curvature and the time-dependency as second order effects, with a meaningful impact on the similarity pattern in the first order. The air flow over the ocean surface is modelled using an outer, inviscid half-infinite flow, overlaying the viscous boundary layer above the wavy surface. The assumption of a uniform flow in the outer layer, used in former studies, is now replaced with a precise analytical solution of the potential flow over a moving wavy surface with a known celerity, wavelength and amplitude. This results in a conceptual change from former models as it shows that the pressure variations within the boundary layer cannot be neglected. In the boundary layer, time-dependent Navier-Stokes equations are formulated in a curvilinear, orthogonal coordinate system. The formulation is done in an elaborate way that presents additional, formerly neglected first-order effects, resulting from the time-varying coordinate system. The suggested time-dependent curvilinear orthogonal coordinate system introduces a platform that can also support the formulation of turbulent problems for any surface shape. In order to produce a self-similar Blasius-type solution, a small wave-steepness is assumed and a perturbation method is applied. Consequently, a

  19. Surface charge and wetting characteristics of layered silicate minerals.

    PubMed

    Yin, Xihui; Gupta, Vishal; Du, Hao; Wang, Xuming; Miller, Jan D

    2012-11-01

    The surface characteristics, including surface charge and wettability, of layered silicates are reviewed based on experimental results and molecular dynamics simulation (MDS) results. The surface charge features of important layered silicates including mica, talc, and kaolinite are described from atomic force microscopy (AFM) measurements, electrophoresis measurements, and/or results from potentiometric titration. In addition, the wetting characteristics of the silica tetrahedral surface which is common to all layered silicates are examined with different experimental techniques and results are discussed. The wettability of trilayer silicates and bilayer silicates is discussed, particularly the wettability of the silica tetrahedral face and alumina octahedral face of kaolinite based on MDS results as well as recent AFM results. PMID:22809732

  20. Modification of surfaces and surface layers by non equilibrium processes

    NASA Astrophysics Data System (ADS)

    Beamson, G.; Brennan, W. J.; Clark, D. T.; Howard, J.

    1988-01-01

    Methods for using plasma in the synthesis and modification of materials in ways impossible by conventional routes are introduced. The equipment used in these methods is described. The chemical analysis of polymer surfaces undergoing modification by inert gas, hydrogen or oxygen plasmas is shown to give physical information regarding the relative roles of diffusion of active species and direct and radiative energy transfer from the plasma. Surface modification by plasma depositing a new material onto an existing substrate is discussed with particular reference to the deposition of amorphous carbon films. Applications of the unique properties of these films are outlined together with current understanding of these properties based on chemical and physical methods of analysis of both the films and the plasmas producing them. Finally, surface modification by ion beams is briefly illustrated using examples from the electronics and metals industries.

  1. Vapor layer evolution during drop impact on a heated surface

    NASA Astrophysics Data System (ADS)

    Lee, Sanghyeon; Lee, Sangjun; Lee, Jisan; Fezzaa, Kamel; Je, Jung Ho

    2015-11-01

    When a liquid drop impacts on a sufficiently hot surface above the boiling point, a vapor layer is formed between the drop and the surface, preventing direct contact between them and as a result levitating the drop, known as the Leidenfrost effect. Understanding the evolution of the vapor layer is largely unexplored despite its importance in estimating heat transfer in cooling systems of thermal or nuclear power plants. The side-profile visualization of the vapor layer, as absolutely required for investigating its evolution, has been however unavailable by conventional optical microscopy. In this study, by employing ultrafast X-ray phase contrast imaging, we directly visualize the profiles of the vapor layers during liquid drop impact on a hot surface and elucidate the evolution of the vapor layers during spreading and retraction of the drop as functions of impact height and surface temperature. We reveal that the evolution is governed by the propagation of capillary waves generated in retraction and the wavelength of capillary waves λ is inversely proportional to the impact height h with a relation ~σ/ρh ~We-1 where We is weber number. Capillary waves that converge at the center of the vapor layers are linked to the bouncing behavior of the drop.

  2. Method for producing functionally graded nanocrystalline layer on metal surface

    DOEpatents

    Ajayi, Oyelayo O.; Hershberger, Jeffrey G.

    2010-03-23

    An improved process for the creation or formation of nanocrystalline layers on substrates' surfaces is provided. The process involves "prescuffing" the surface of a substrate such as a metal by allowing friction to occur on the surface by a load-bearing entity making rubbing contact and moving along and on the substrate's surface. The "prescuffing" action is terminated when the coefficient of friction between the surface and the noise is rising significantly. Often, the significant rise in the coefficient of friction is signaled by a change in pitch of the scuffing action sound emanating from the buffeted surface. The "prescuffing" gives rise to a harder and smoother surface which withstands better any inadequate lubrication that may take place when the "prescuffed" surface is contacted by other surfaces.

  3. Directional dependence of surface morphological stability of heteroepitaxial layers

    NASA Astrophysics Data System (ADS)

    Obayashi, Y.; Shintani, K.

    1998-09-01

    Surface morphological stability in coherent heteroepitaxial layers is analyzed focusing on the directional dependence of surface undulations created by surface diffusion. The critical stability condition is defined in terms of the free energy of the system which is assumed to be the sum of the elastic strain energy and the surface free energy. The displacement and stress fields of the semi-infinite anisotropic solid with the slightly undulating surface are calculated by using the surface admittance tensor and the vector complex potential function. Numerical results for the Si1-xGex/Si systems show that the critical wavelength of the <100> surface undulations is smaller than that of the <110> surface undulations, which means that surface undulations are likely to be formed in the <100> directions. It is also found that the critical wavelength decreases with the increase of Ge fraction. These tendencies are in good agreement with the observations in annealing experiments for the Si1-xGex/Si systems in the literature. If the substrate is assumed to be rigid, the range of layer thickness where the system is absolutely stable against a surface undulation of any wavelength exists. Finally, the growth rate of the amplitude of surface undulations is estimated from an evolution equation for the surface shape. It is shown that even if anisotropy is taken into account, the growth rate of the amplitude takes the maximum value when the wavelength is 4/3 times the critical wavelength, which is the same as in the isotropic approximation.

  4. Atomic and molecular layer deposition for surface modification

    SciTech Connect

    Vähä-Nissi, Mika; Sievänen, Jenni; Salo, Erkki; Heikkilä, Pirjo; Kenttä, Eija; Johansson, Leena-Sisko; Koskinen, Jorma T.; Harlin, Ali

    2014-06-01

    Atomic and molecular layer deposition (ALD and MLD, respectively) techniques are based on repeated cycles of gas–solid surface reactions. A partial monolayer of atoms or molecules is deposited to the surface during a single deposition cycle, enabling tailored film composition in principle down to molecular resolution on ideal surfaces. Typically ALD/MLD has been used for applications where uniform and pinhole free thin film is a necessity even on 3D surfaces. However, thin – even non-uniform – atomic and molecular deposited layers can also be used to tailor the surface characteristics of different non-ideal substrates. For example, print quality of inkjet printing on polymer films and penetration of water into porous nonwovens can be adjusted with low-temperature deposited metal oxide. In addition, adhesion of extrusion coated biopolymer to inorganic oxides can be improved with a hybrid layer based on lactic acid. - Graphical abstract: Print quality of a polylactide film surface modified with atomic layer deposition prior to inkjet printing (360 dpi) with an aqueous ink. Number of printed dots illustrated as a function of 0, 5, 15 and 25 deposition cycles of trimethylaluminum and water. - Highlights: • ALD/MLD can be used to adjust surface characteristics of films and fiber materials. • Hydrophobicity after few deposition cycles of Al{sub 2}O{sub 3} due to e.g. complex formation. • Same effect on cellulosic fabrics observed with low temperature deposited TiO{sub 2}. • Different film growth and oxidation potential with different precursors. • Hybrid layer on inorganic layer can be used to improve adhesion of polymer melt.

  5. Multi-layer surface profiling using gated wavefront sensing

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Nordin, Nur Dalilla; Tik, Eddy Chow Mun; Tan, ChingSeong; Chew, Kuew Wai; Menoni, Carmen

    2015-01-01

    Recently, multi-layer surface profiling and inspection has been considered an emerging topic that can be used to solve various manufacturing inspection problems, such as graded index lenses, TSV (Thru-Silicon Via), and optical coating. In our study, we proposed a gated wavefront sensing approach to estimate the multi-layer surface profile. In this paper, we set up an experimental platform to validate our theoretical models and methods. Our test bed consists of pulse laser, collimator, prism, well-defined focusing lens, testing specimen, and gated wavefront sensing assembly (e.g., lenslet and gated camera). Typical wavefront measurement steps are carried out for the gated system, except the reflectance is timed against its time of flight as well as its intensity profile. By synchronizing the laser pulses to the camera gate time, it is possible to discriminate a multi-layer wavefront from its neighbouring discrete layer reflections.

  6. Synthesis and characterization of macromolecular layers grafted to polymer surfaces

    NASA Astrophysics Data System (ADS)

    Burtovyy, Oleksandr

    The composition and behavior of surfaces and interfaces play a pivotal role in dictating the overall efficiency of the majority of polymeric materials and devices. Surface properties of the materials can be altered using surface modification techniques. It is necessary to highlight that successful methods of surface modification should affect only the upper layer of the polymer material without changing bulk properties. The processes must introduce new functionalities to the surface, optimize surface roughness, lubrication, hydrophobicity, hydrophilicity, adhesion, conductivity, and/or biocompatibility. Research presented in this dissertation is dedicated to the synthesis, characterization, and application of thin macromolecular layers anchored to polymer substrates. Specifically, attachment of functional polymers via a "grafting to" approach has been extensively studied using PET and nylon model substrates. First, poly(glycidyl methacrylate) was used to introduce permanent functionalities to the model substrates by anchoring it to model films. Then, three different functional polymers were grafted on top of the previous layer. As one part of this study, the temperature and time dependence of grafting functional layers were studied. The surface coverage by hydrophobic polymer was determined from experimental data and predicted by a model. In general, the model has a high degree of predictive capability. Next, surface modification of polymeric fibers and membranes is presented as an important application of the polymer thin layers targeted in the study. Specifically, the procedures developed for surface modification of model substrates was employed for modification of PET, nylon, and cotton fabrics as well as PET track-etched membranes. Since epoxy groups are highly reactive in various chemical reactions, the approach becomes virtually universal, allowing both various surfaces and end-functionalized macromolecules to be used in the grafted layer synthesis. PET

  7. Surface stress of graphene layers supported on soft substrate

    PubMed Central

    Du, Feng; Huang, Jianyong; Duan, Huiling; Xiong, Chunyang; Wang, Jianxiang

    2016-01-01

    We obtain the surface stress of a single layer and multilayers of graphene supported on silicone substrates by measuring the deformation of the graphene-covered substrates induced by the surface tension of liquid droplets together with the Neumann’s triangle concept. We find that the surface stress of the graphene-covered substrate is significant larger than that of the bare substrate, and it increases with increasing graphene layers, and finally reaches a constant value of about 120 mN/m on three and more layers of graphene. This work demonstrates that the apparent surface stress of graphene-substrate systems can be tuned by the substrate and the graphene layers. The surface stress and the tuning effect of the substrate on it may have applications in design and characterization of graphene-based ultra-sensitive sensors and other devices. Moreover, the method may also be used to measure the surface stress of other ultrathin films supported on soft substrates. PMID:27166087

  8. Surface stress of graphene layers supported on soft substrate.

    PubMed

    Du, Feng; Huang, Jianyong; Duan, Huiling; Xiong, Chunyang; Wang, Jianxiang

    2016-01-01

    We obtain the surface stress of a single layer and multilayers of graphene supported on silicone substrates by measuring the deformation of the graphene-covered substrates induced by the surface tension of liquid droplets together with the Neumann's triangle concept. We find that the surface stress of the graphene-covered substrate is significant larger than that of the bare substrate, and it increases with increasing graphene layers, and finally reaches a constant value of about 120 mN/m on three and more layers of graphene. This work demonstrates that the apparent surface stress of graphene-substrate systems can be tuned by the substrate and the graphene layers. The surface stress and the tuning effect of the substrate on it may have applications in design and characterization of graphene-based ultra-sensitive sensors and other devices. Moreover, the method may also be used to measure the surface stress of other ultrathin films supported on soft substrates. PMID:27166087

  9. Surface stress of graphene layers supported on soft substrate

    NASA Astrophysics Data System (ADS)

    Du, Feng; Huang, Jianyong; Duan, Huiling; Xiong, Chunyang; Wang, Jianxiang

    2016-05-01

    We obtain the surface stress of a single layer and multilayers of graphene supported on silicone substrates by measuring the deformation of the graphene-covered substrates induced by the surface tension of liquid droplets together with the Neumann’s triangle concept. We find that the surface stress of the graphene-covered substrate is significant larger than that of the bare substrate, and it increases with increasing graphene layers, and finally reaches a constant value of about 120 mN/m on three and more layers of graphene. This work demonstrates that the apparent surface stress of graphene-substrate systems can be tuned by the substrate and the graphene layers. The surface stress and the tuning effect of the substrate on it may have applications in design and characterization of graphene-based ultra-sensitive sensors and other devices. Moreover, the method may also be used to measure the surface stress of other ultrathin films supported on soft substrates.

  10. The Turbulent Boundary Layer on a Rough Curvilinear Surface

    NASA Technical Reports Server (NTRS)

    Droblenkov, V. F.

    1958-01-01

    A number of semiempirical approximate methods exist for determining the characteristics of the turbulent boundary layer on a curvilinear surface. At present, among these methods, the one proposed by L. G. Loitsianskii is given frequent practical application. This method is sufficiently effective and permits, in the case of wing profiles with technically smooth surfaces, calculating the basic characteristics of the boundary layer and the values of the overall drag with an accuracy which suffices for practical purposes. The idea of making use of the basic integral momentum equation ((d delta(sup xx))/dx) + ((V' delta(sup xx))/V) (2 + H) = (tau(sub 0))/(rho V(exp 2)) proves to be fruitful also for the solution of the problems in the determination of the characteristics of the turbulent boundary layer on a rough surface.

  11. An experimental investigation of turbulent boundary layers along curved surfaces

    NASA Technical Reports Server (NTRS)

    So, R. M. C.; Mellor, G. L.

    1972-01-01

    A curved wall tunnel was designed, and an equilibrium turbulent boundary layer was set up on the straight section preceding the curved test section. Turbulent boundary layer flows with uniform and adverse pressure distributions along convex and concave walls were investigated. Hot-wire measurements along the convex surface indicated that turbulent mixing between fluid layers was very much reduced. However, the law of the wall held and the skin friction, thus determined, correlated well with other measurements. Hot-wire measurements along the concave test wall revealed a system of longitudinal vortices inside the boundary layer and confirmed that concave curvature enhances mixing. A self-consistent set of turbulent boundary layer equations for flows along curved surfaces was derived together with a modified eddy viscosity. Solution of these equations together with the modified eddy viscosity gave results that correlated well with the present data on flows along the convex surface with arbitrary pressure distribution. However, it could only be used to predict the mean characteristics of the flow along concave walls because of the existence of the system of longitudinal vortices inside the boundary layer.

  12. Assessment of surface turbulent fluxes using geostationary satellite surface skin temperatures and a mixed layer planetary boundary layer scheme

    NASA Technical Reports Server (NTRS)

    Diak, George R.; Stewart, Tod R.

    1989-01-01

    A method is presented for evaluating the fluxes of sensible and latent heating at the land surface, using satellite-measured surface temperature changes in a composite surface layer-mixed layer representation of the planetary boundary layer. The basic prognostic model is tested by comparison with synoptic station information at sites where surface evaporation climatology is well known. The remote sensing version of the model, using satellite-measured surface temperature changes, is then used to quantify the sharp spatial gradient in surface heating/evaporation across the central United States. An error analysis indicates that perhaps five levels of evaporation are recognizable by these methods and that the chief cause of error is the interaction of errors in the measurement of surface temperature change with errors in the assigment of surface roughness character. Finally, two new potential methods for remote sensing of the land-surface energy balance are suggested which will relay on space-borne instrumentation planned for the 1990s.

  13. Surface reactions on thin layers of silane coupling agents

    SciTech Connect

    Kurth, D.G.; Bein, T. )

    1993-11-01

    The reactivity of immobilized functional groups in thin layers of (3-aminopropyl)triethoxysilane (APS), (3-mercaptopropyl)trimethoxysilane, (3-bromopropyl)trimethoxysilane, and (8-bromooctyl)trimethoxysilane on oxidized aluminum substrates was studied with reflection-adsorption infrared spectroscopy (RAIR), optical ellipsometry and contact-angle measurements. Mass changes on the surface associated with the surface-confined reactions were measured with the quartz crystal microbalance (QCM). Single layers of (3-aminopropyl)triethoxysilane on oxidized aluminum react with chlorodimethylsilane to give [(-O)[sub 3]Si(CH[sub 2])[sub 3]NH[sub 2][sup +]SiMe[sub 2]H]Cl[sup [minus

  14. S-nitrosothiols regulate cell-surface pH buffering by airway epithelial cells during the human immune response to rhinovirus.

    PubMed

    Carraro, Silvia; Doherty, Joseph; Zaman, Khalequz; Gainov, Iain; Turner, Ronald; Vaughan, John; Hunt, John F; Márquez, Javier; Gaston, Benjamin

    2006-05-01

    Human rhinovirus infection is a common trigger for asthma exacerbations. Asthma exacerbations and rhinovirus infections are both associated with markedly decreased pH and ammonium levels in exhaled breath condensates. This observation is thought to be related, in part, to decreased activity of airway epithelial glutaminase. We studied whether direct rhinovirus infection and/or the host immune response to the infection decreased airway epithelial cell surface pH in vitro. Interferon-gamma and tumor necrosis factor-alpha, but not direct rhinovirus infection, decreased pH, an effect partly associated with decreased ammonium concentrations. This effect was 1) prevented by nitric oxide synthase inhibition; 2) independent of cyclic GMP; 3) associated with an increase in endogenous airway epithelial cell S-nitrosothiol concentration; 4) mimicked by the exogenous S-nitrosothiol, S-nitroso-N-acetyl cysteine; and 5) independent of glutaminase expression and activity. We then confirmed that decreased epithelial pH inhibits human rhinovirus replication in airway epithelial cells. These data suggest that a nitric oxide synthase-dependent host response to viral infection mediated by S-nitrosothiols, rather than direct infection itself, plays a role in decreased airway surface pH during human rhinovirus infection. This host immune response may serve to protect the lower airways from direct infection in the normal host. In patients with asthma, however, this fall in pH could be associated with the increased mucus production, augmented inflammatory cell degranulation, bronchoconstriction, and cough characteristic of an asthma exacerbation. PMID:16603595

  15. Evolving surface cusps during strained-layer epitaxy

    SciTech Connect

    Jesson, D.E.; Pennycook, S.J.; Baribeau, J.M.; Houghton, D.C.

    1993-04-01

    We have combined Z-contrast imaging and Ge marker layer experiments to study the evolving surface morphology of Si{sub x}Ge{sub 1-x} alloys grown by molecular beam epitaxy (MBE). Surface cusps are seen to arise as the intersection lines between coherent islands. The potential implications of stress concentrations associated with cusps are considered with a view to strain relaxation in the film via dislocation nucleation.

  16. Surface morphological evolution during annealing of epitaxial Cu(001) layers

    SciTech Connect

    Purswani, J. M.; Gall, D.

    2008-08-15

    Single crystal Cu(001) layers were grown on MgO(001) by ultrahigh vacuum magnetron sputtering at T{sub s}=100 deg. C. Quantitative surface morphological analyses by in situ scanning tunneling microscopy show that the surfaces exhibit self-affine mound structures with a scaling exponent of 0.82{+-}0.03 and a mound radius r{sub c} that increases from 31{+-}8 to 39{+-}6 nm for increasing layer thickness t=24-120 nm. In situ annealing at 200 and 300 deg. C leads to a thermodynamically driven mass transport that minimizes the surface step density, resulting in broader mounds and a smaller root mean square surface roughness {sigma}. This effect is most pronounced for t=24 nm, for which r{sub c} increases from 31{+-}8 to 70{+-}20 nm and {sigma} decreases from 1.3{+-}0.1 to 0.74{+-}0.08 nm, resulting in a decrease in the average surface slope from {chi}=7 deg. to 2 deg. and an increase in the average terrace width w{sub T} by more than a factor of 4. In contrast, w{sub T} increases by only 20% for t=120 nm. This remarkable difference between 'thin' and 'thick' layers is attributed to diverging surface morphological pathways during annealing: The strong smoothening for t=24 nm is due to a competitive coalescence process where some mounds grow laterally at the expense of their smaller neighbors, which die out. In contrast, the initially wider mounds of thicker layers (t=120 nm) combine to form a quasistable surface morphology that exhibits anisotropic mound structures, which limit mass transport and stabilize the surface step density.

  17. A scheme for computing surface layer turbulent fluxes from mean flow surface observations

    NASA Technical Reports Server (NTRS)

    Hoffert, M. I.; Storch, J.

    1978-01-01

    A physical model and computational scheme are developed for generating turbulent surface stress, sensible heat flux and humidity flux from mean velocity, temperature and humidity at some fixed height in the atmospheric surface layer, where conditions at this reference level are presumed known from observations or the evolving state of a numerical atmospheric circulation model. The method is based on coupling the Monin-Obukov surface layer similarity profiles which include buoyant stability effects on mean velocity, temperature and humidity to a force-restore formulation for the evolution of surface soil temperature to yield the local values of shear stress, heat flux and surface temperature. A self-contained formulation is presented including parameterizations for solar and infrared radiant fluxes at the surface. Additional parameters needed to implement the scheme are the thermal heat capacity of the soil per unit surface area, surface aerodynamic roughness, latitude, solar declination, surface albedo, surface emissivity and atmospheric transmissivity to solar radiation.

  18. Epithelial hyperplasia, airways

    Cancer.gov

    Number of respiratory epithelial cells is increased diffusely or focally. Frequently luminal protrusions are observed, sometimes forming papillae. Mucous (goblet) cell metaplastic hyperplasia is a variant, in which the respiratory epithelium of conducting airways is replaced by mucous cells either as a single or a pseudostratified layer.

  19. Laminarization of Turbulent Boundary Layer on Flexible and Rigid Surfaces

    NASA Technical Reports Server (NTRS)

    Maestrello, Lucio

    2001-01-01

    An investigation of the control of turbulent boundary layer flow over flexible and rigid surfaces downstream of a concave-convex geometry has been made. The concave-convex curvature induces centrifugal forces and a pressure gradient on the growth of the turbulent boundary layer. The favorable gradient is not sufficient to overcome the unfavorable; thus, the net effect is a destabilizing, of the flow into Gortler instabilities. This study shows that control of the turbulent boundary layer and structural loading can be successfully achieved by using localized surface heating because the subsequent cooling and geometrical shaping downstream over a favorable pressure gradient is effective in laminarization of the turbulence. Wires embedded in a thermally insulated substrate provide surface heating. The laminarized velocity profile adjusts to a lower Reynolds number, and the structure responds to a lower loading. In the laminarization, the turbulent energy is dissipated by molecular transport by both viscous and conductivity mechanisms. Laminarization reduces spanwise vorticity because of the longitudinal cooling gradient of the sublayer profile. The results demonstrate that the curvature-induced mean pressure gradient enhances the receptivity of the flow to localized surface heating, a potentially viable mechanism to laminarize turbulent boundary layer flow; thus, the flow reduces the response of the flexible structure and the resultant sound radiation.

  20. Surface modification of layered zirconium phosphate with PNIPAM.

    PubMed

    Wang, Xuezhen; Zhao, Di; Medina, Ilse B Nava; Diaz, Agustin; Wang, Huiliang; Clearfield, Abraham; Mannan, M Sam; Cheng, Zhengdong

    2016-04-01

    A new method was reported to modify layered zirconium phosphate (ZrP) with thermoresponsive polymer PNIPAM (poly N-isopropylacrylamide). PNIPAM was proved to be covalently grafted onto ZrP. (60)Co γ-rays irradiation produced peroxide groups on the surface which, upon heating, initiated free radical polymerization and subsequent attachment of PNIPAM. PMID:26966882

  1. NMR of thin layers using a meanderline surface coil

    DOEpatents

    Cowgill, Donald F.

    2001-01-01

    A miniature meanderline sensor coil which extends the capabilities of nuclear magnetic resonance (NMR) to provide analysis of thin planar samples and surface layer geometries. The sensor coil allows standard NMR techniques to be used to examine thin planar (or curved) layers, extending NMRs utility to many problems of modern interest. This technique can be used to examine contact layers, non-destructively depth profile into films, or image multiple layers in a 3-dimensional sense. It lends itself to high resolution NMR techniques of magic angle spinning and thus can be used to examine the bonding and electronic structure in layered materials or to observe the chemistry associated with aging coatings. Coupling this sensor coil technology with an arrangement of small magnets will produce a penetrator probe for remote in-situ chemical analysis of groundwater or contaminant sediments. Alternatively, the sensor coil can be further miniaturized to provide sub-micron depth resolution within thin films or to orthoscopically examine living tissue. This thin-layer NMR technique using a stationary meanderline coil in a series-resonant circuit has been demonstrated and it has been determined that the flat meanderline geometry has about he same detection sensitivity as a solenoidal coil, but is specifically tailored to examine planar material layers, while avoiding signals from the bulk.

  2. Mercurian megaregolith layer and surface heat flows constraints

    NASA Astrophysics Data System (ADS)

    Egea-Gonzalez, Isabel; Ruiz, Javier

    2013-04-01

    Mercury is covered by a thermally insulating megaregolith layer. Despite the fact that it is known that this poor conducting layer has important influences on surface heat flows, most thermal modeling studies have overlooked it. Mercurian megaregolith is not very well known, but data provided by MESSENGER suggest that mercurian megaregolith is less insulating than its lunar counterpart. This information together with brittle-ductile transition (BDT) depths, estimated from the analysis of fault geometries associated with lobate scarps, allow us to constrain the surface heat flow on Mercury at the time of scarps formation. In this work, we have solved the heat conduction equation in order to constrain surface heat flows. Firstly, we obtain an upper limit in surface heat flows by using published values of the BDT depth and by neglecting the megaregolith layer. Then, we calculate a lower limit by including in the heat equation a top layer with thermal properties representative of the lunar megaregolith. In our calculations we have taken into account volumetric heat production rates obtained from the surface abundances of radioactive elements provided by MESSENGER. Heat equation solutions constrain surface heat flows to a range of 6 - 29 mWm-2. These results suggest the possibility that surface heat flows could be lower than those calculated in previous works, which is in agreement with the small amount of radial contraction detected on Mercury. Furthermore, the procedure followed in this article can be easily applied to other planets and satellites, which will improve our knowledge about the thermal evolution of these bodies.

  3. Hierarchy of adhesion forces in patterns of photoreactive surface layers

    NASA Astrophysics Data System (ADS)

    Hlawacek, Gregor; Shen, Quan; Teichert, Christian; Lex, Alexandra; Trimmel, Gregor; Kern, Wolfgang

    2009-01-01

    Precise control of surface properties including electrical characteristics, wettability, and friction is a prerequisite for manufacturing modern organic electronic devices. The successful combination of bottom up approaches for aligning and orienting the molecules and top down techniques to structure the substrate on the nano- and micrometer scale allows the cost efficient fabrication and integration of future organic light emitting diodes and organic thin film transistors. One possibility for the top down patterning of a surface is to utilize different surface free energies or wetting properties of a functional group. Here, we used friction force microscopy (FFM) to reveal chemical patterns inscribed by a photolithographic process into a photosensitive surface layer. FFM allowed the simultaneous visualization of at least three different chemical surface terminations. The underlying mechanism is related to changes in the chemical interaction between probe and film surface.

  4. Effects of mesoscale surface inhomogeneities on atmospheric boundary layer transfer

    SciTech Connect

    Shaw, W.J.; Doran, J.C.; Hubbe, J.M.

    1992-09-01

    Defining the nature of turbulent transfer over horizontally inhomogeneous surfaces remains one of the challenges in meteorology. Because the transfer of energy and momentum through the atmospheric boundary layer forms part of the lower boundary condition for global climate models (GCMs), the problem is important. Over the last two decades, advances in sensor and computer technology wave made good point measurements of turbulent fluxes fairly routine. A fundamental question with respect to climate models, however, is how such point measurements are related to average fluxes over the area of a GCM grid box. In this paper we will use data from the field program to depict the evolution of the boundary layer over adjacent, sharply contrasting surface types on two separate occasions. We will then use simple scaling based on the observations to argue that sub-gridscale motions would often be likely to significantly alter the estimates and resulting parameterizations of GCM-scale surface fluxes in the region.

  5. Nucleation and Early Stages of Layer-by-Layer Growth of Metal Organic Frameworks on Surfaces

    PubMed Central

    2015-01-01

    High resolution atomic force microscopy (AFM) is used to resolve the evolution of crystallites of a metal organic framework (HKUST-1) grown on Au(111) using a liquid-phase layer-by-layer methodology. The nucleation and faceting of individual crystallites is followed by repeatedly imaging the same submicron region after each cycle of growth and we find that the growing surface is terminated by {111} facets leading to the formation of pyramidal nanostructures for [100] oriented crystallites, and triangular [111] islands with typical lateral dimensions of tens of nanometres. AFM images reveal that crystallites can grow by 5–10 layers in each cycle. The growth rate depends on crystallographic orientation and the morphology of the gold substrate, and we demonstrate that under these conditions the growth is nanocrystalline with a morphology determined by the minimum energy surface. PMID:26709359

  6. Ultrastructure of the Bacteroides nodosus cell envelope layers and surface.

    PubMed Central

    Every, D; Skerman, T M

    1980-01-01

    The surface structure and cell envelope layers of various virulent Bacteroides nodosus strains were examined by light microscopy and by electron microscopy by using negative staining, thin-section, and freeze-fracture-etch techniques. Three surface structures were described: pili and a diffuse material, both of which emerged from one or both poles of the bacteria (depending on the stage of growth and division), and large rodlike structures (usually 30 to 40 nm in diameter) associated with a small proportion of the bacterial population. No capsule was detected. The cell envelope consisted of four layers: a plasma membrane, a peptidoglycan layer, an outer membrane, and an outermost additional layer. The additional layer was composed of subunits, generally hexagonally packed with center-to-center spacing of 6 to 7 nm. The outer membrane and plasma membrane freeze-fractured through their hydrophobic regions revealing four fracture faces with features similar to those of other gram-negative bacteria. However, some unusual features were seen on the fracture faces of the outer membrane: large raised ring structure (11 to 12 nm in diameter) on cw 3 at the poles of the bacteria; complementary pits or ring-shaped depressions on cw 2; and small raised ring structures (7 to 8 nm in diameter) all over cw 2. Images PMID:6154040

  7. Friedel oscillations at the surfaces of rhombohedral N -layer graphene

    NASA Astrophysics Data System (ADS)

    Dutreix, C.; Katsnelson, M. I.

    2016-01-01

    The low-energy physics of rhombohedral N -layer graphene mainly arises on the external layers, where most of the π electrons are located. Their Bloch band structure defines a two-band semimetal; the dispersion relation scales as ±qN with the momentum norm q in the vicinity of two nonequivalent valleys. In this paper, we address the problem of elastic scattering through a localized impurity located either on the surface of the material or within the bulk, and focus on the quantum interferences it induces on the two external layers. It is apprehended in the framework of a T -matrix approach, both numerically and analytically, regardless of the impurity magnitude, which enables the description of realistic scatters. In rhombohedral multilayer graphene, the impurity induces Friedel oscillations that always decay as 1 /r . As a result, monolayer graphene is the only material of the rhombohedral class that exhibits 1 /r2 -decaying Friedel oscillations. The interference patterns are subsequently analyzed in momentum space. This analysis enables a clear distinction between monolayer graphene and multilayer graphene. It also shows that the interference pattern reveals the whole Bloch band structure, and highlights the number of layers stacked in the material, as well as the π -quantized Berry phases that characterize the existence of nodal points in the semimetallic spectrum. Experimentally, these features may be probed from scanning tunneling microscopy, when imaging the local density of states at the surfaces of suspended rhombohedral N -layer graphene.

  8. The Role of Surface Layer Processes in Solid Propellant Combustion.

    NASA Astrophysics Data System (ADS)

    Chakravarthy, Satyanarayanan R.

    The qualitative multidimensional theory of composite solid propellant combustion based on the sandwich burning methodology was applied to certain specific problems: (a) burning rate enhancement by ferric oxide, (b) plateau burning behavior caused by binder melt flow effects, and (c) characterization of the combustion of new energetic oxidizers--ADN and HNIW. Exothermic reactions at the interfacial contact lines between AP particles and the binder in the surface layer of the burning propellant assume significance in the presence of ferric oxide, and control the burning rate. Binder melt flow covers adjacent AP particle surfaces increasingly at higher pressures, and disperses the O/F leading edge flames attached to coarse particles. It also causes fine AP/binder matrix areas on the surface not to support a steady premixed flame at intermediate pressures, resulting in an overall decrease in the burning rate with increasing pressure, which implies plateau or mesa effects. ADN self -deflagration rate is significantly higher than that of AP, and controls the sandwich burning rate to a great extent. The O/F flame of ADN and binder still behaves as rate limiting, although strongly supported by ADN self-deflagration. ADN melts and vaporizes substantially before the binder, allowing for the possibility of complex physical processes in the surface layer. The strong exothermic decomposition of HNIW at moderate temperatures causes the oxidizer particles in the surface layer to be the sites of burning rate control. The problems addressed in this study combinedly point to the significance of crucial surface layer processes under the situations of interest, and signal a need to characterize such processes directly and in greater detail.

  9. Oxygen inhibition layer of composite resins: effects of layer thickness and surface layer treatment on the interlayer bond strength.

    PubMed

    Bijelic-Donova, Jasmina; Garoushi, Sufyan; Lassila, Lippo V J; Vallittu, Pekka K

    2015-02-01

    An oxygen inhibition layer develops on surfaces exposed to air during polymerization of particulate filling composite. This study assessed the thickness of the oxygen inhibition layer of short-fiber-reinforced composite in comparison with conventional particulate filling composites. The effect of an oxygen inhibition layer on the shear bond strength of incrementally placed particulate filling composite layers was also evaluated. Four different restorative composites were selected: everX Posterior (a short-fiber-reinforced composite), Z250, SupremeXT, and Silorane. All composites were evaluated regarding the thickness of the oxygen inhibition layer and for shear bond strength. An equal amount of each composite was polymerized in air between two glass plates and the thickness of the oxygen inhibition layer was measured using a stereomicroscope. Cylindrical-shaped specimens were prepared for measurement of shear bond strength by placing incrementally two layers of the same composite material. Before applying the second composite layer, the first increment's bonding site was treated as follows: grinding with 1,000-grit silicon-carbide (SiC) abrasive paper, or treatment with ethanol or with water-spray. The inhibition depth was lowest (11.6 μm) for water-sprayed Silorane and greatest (22.9 μm) for the water-sprayed short-fiber-reinforced composite. The shear bond strength ranged from 5.8 MPa (ground Silorane) to 36.4 MPa (water-sprayed SupremeXT). The presence of an oxygen inhibition layer enhanced the interlayer shear bond strength of all investigated materials, but its absence resulted in cohesive and mixed failures only with the short-fiber-reinforced composite. Thus, more durable adhesion with short-fiber-reinforced composite is expected. PMID:25556290

  10. Plasma behavior in the boundary layer near a railgun surface

    SciTech Connect

    Kang, S.W.; McCallen, R. )

    1989-01-01

    Viscous flow and thermal characteristics are theoretically analyzed for the plasma behind a moving projectile inside a railgun. When only convective effects are included in the turbulent boundary layer analysis, the results suggest a temperature maximum in the wall region for very high velocity flows. The case of radiative as well as convective transport has also been investigated for an optically thick boundary layer flow by application of an approximate method. Results show a sizable effect of radiation on the flow characteristics, especially on the heat transfer rate to the railgun surface.

  11. Plasma behavior in the boundary layer near a railgun surface

    SciTech Connect

    Kang, Sang-Wook; McCallen, R.E.

    1988-03-01

    Viscous flow and thermal characteristics are theoretically analyzed for the plasma behind a moving projectile inside a railgun. When only convective effects are included in the turbulent boundary layer analysis, the results suggest a temperature maximum in the wall region for very high velocity flows. The case of radiative as well as convective transport has also been investigated for an optically-thick boundary layer flow by application of an approximate method. Results show a sizable effect of radiation on the flow characteristics, especially on the heat-transfer rate to the railgun surface. 7 refs., 2 figs.

  12. Modification of Surface Layers by Surfacing Intermetallic Coatings with Variable Properties

    NASA Astrophysics Data System (ADS)

    Makeev, D. N.; Zakharov, O. V.; Vinogradov, A. N.; Kochetkov, A. V.

    2016-02-01

    The paper considers the possibility of forming coating layers for parts within wide limits of microhardness. The technology uses surfacing of intermetallic coatings provided by a unique experimental setup. Theoretical and experimental dependence of the coating layer microhardness on the filler concentration using the changes in the speed of the filler wire feed and current intensity were determined.

  13. 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

  14. CX3CR1 is an important surface molecule for respiratory syncytial virus infection in human airway epithelial cells

    PubMed Central

    Chirkova, Tatiana; Lin, Songbai; Oomens, Antonius G. P.; Gaston, Kelsey A.; Boyoglu-Barnum, Seyhan; Meng, Jia; Stobart, Christopher C.; Cotton, Calvin U.; Hartert, Tina V.; Moore, Martin L.; Ziady, Assem G.

    2015-01-01

    Respiratory syncytial virus (RSV) is a major cause of severe pneumonia and bronchiolitis in infants and young children, and causes disease throughout life. Understanding the biology of infection, including virus binding to the cell surface, should help develop antiviral drugs or vaccines. The RSV F and G glycoproteins bind cell surface heparin sulfate proteoglycans (HSPGs) through heparin-binding domains. The G protein also has a CX3C chemokine motif which binds to the fractalkine receptor CX3CR1. G protein binding to CX3CR1 is not important for infection of immortalized cell lines, but reportedly is so for primary human airway epithelial cells (HAECs), the primary site for human infection. We studied the role of CX3CR1 in RSV infection with CX3CR1-transfected cell lines and HAECs with variable percentages of CX3CR1-expressing cells, and the effect of anti-CX3CR1 antibodies or a mutation in the RSV CX3C motif. Immortalized cells lacking HSPGs had low RSV binding and infection, which was increased markedly by CX3CR1 transfection. CX3CR1 was expressed primarily on ciliated cells, and ∼50 % of RSV-infected cells in HAECs were CX3CR1+. HAECs with more CX3CR1-expressing cells had a proportional increase in RSV infection. Blocking G binding to CX3CR1 with anti-CX3CR1 antibody or a mutation in the CX3C motif significantly decreased RSV infection in HAECs. The kinetics of cytokine production suggested that the RSV/CX3CR1 interaction induced RANTES (regulated on activation normal T-cell expressed and secreted protein), IL-8 and fractalkine production, whilst it downregulated IL-15, IL1-RA and monocyte chemotactic protein-1. Thus, the RSV G protein/CX3CR1 interaction is likely important in infection and infection-induced responses of the airway epithelium, the primary site of human infection. PMID:26297201

  15. Surface morphological evolution of epitaxial CrN(001) layers

    SciTech Connect

    Frederick, J.R.; Gall, D.

    2005-09-01

    CrN layers, 57 and 230 nm thick, were grown on MgO(001) at T{sub s}=600-800 deg. C by ultrahigh-vacuum magnetron sputter deposition in pure N{sub 2} discharges from an oblique deposition angle {alpha}=80 deg. . Layers grown at 600 deg. C nucleate as single crystals with a cube-on-cube epitaxial relationship with the substrate. However, rough surfaces with cauliflower-type morphologies cause the nucleation of misoriented CrN grains that develop into cone-shaped grains that protrude out of the epitaxial matrix to form triangular faceted surface mounds. The surface morphology of epitaxial CrN(001) grown at 700 deg. C is characterized by dendritic ridge patterns extending along the orthogonal <110> directions superposed by square-shaped super mounds with <100> edges. The ridge patterns are attributed to a Bales-Zangwill instability while the supermounds form due to atomic shadowing which leads to the formation of epitaxial inverted pyramids that are separated from the surrounding layer by tilted nanovoids. Growth at 800 deg. C yields complete single crystals with smooth surfaces. The root-mean-square surface roughness for 230-nm-thick layers decreases from 18.8 to 9.3 to 1.1 nm as T{sub s} is raised from 600 to 700 to 800 deg. C. This steep decrease is due to a transition in the roughening mechanism from atomic shadowing to kinetic roughening. Atomic shadowing is dominant at 600 and 700 deg. C, where misoriented grains and supermounds, respectively, capture a larger fraction of the oblique deposition flux in comparison to the surrounding epitaxial matrix, resulting in a high roughening rate that is described by a power law with an exponent {beta}>0.5. In contrast, kinetic roughening controls the surface morphology for T{sub s}=800 deg. C, as well as the epitaxial fraction of the layers grown at 600 and 700 deg. C, yielding relatively smooth surfaces and {beta}{<=}0.27.

  16. Electrografted diazonium salt layers for antifouling on the surface of surface plasmon resonance biosensors.

    PubMed

    Zou, Qiongjing; Kegel, Laurel L; Booksh, Karl S

    2015-02-17

    Electrografted diazonium salt layers on the surface of surface plasmon resonance (SPR) sensors present potential for a significant improvement in antifouling coatings. A pulsed potential deposition profile was used in order to circumvent mass-transport limitations for layer deposition rate. The influence of number of pulses with respect to antifouling efficacy was evaluated by nonspecific adsorption surface coverage of crude bovine serum proteins. Instead of using empirical and rough estimated values, the penetration depth and sensitivity of the SPR instrument were experimentally determined for the calculation of nonspecific adsorption surface coverage. This provides a method to better examine antifouling surface coatings and compare crossing different coatings and experimental systems. Direct comparison of antifouling performance of different diazonium salts was facilitated by a tripad SPR sensor design. The electrografted 4-phenylalanine diazonium chloride (4-APhe) layers with zwitterionic characteristic demonstrate ultralow fouling. PMID:25526646

  17. Arctic Cloud-driven Mixed Layers and Surface Coupling State

    NASA Astrophysics Data System (ADS)

    Shupe, M.; Persson, O. P.; Solomon, A.; de Boer, G.

    2013-12-01

    Arctic low-level clouds interact with the atmosphere and underlying surface via many inter-related processes. The balance of cloud radiative warming and cooling effects imparts a strong control on the net surface energy budget. Cloud-driven atmospheric circulations can impact surface turbulent heat fluxes and influence the vertical mixing of atmospheric state parameters and aerosols. Large-scale advection of heat and moisture provides the background context within which these local interactions unfold. Importantly, these radiative, dynamical, and advective processes also contribute to a complex web of self-sustaining cloud processes that can promote cloud maintenance over long periods of time. We examine many of these processes, with a specific focus on the dynamical linkages between Arctic clouds and the surface that influence low-level atmospheric structure and mixing. Comprehensive, ground-based observations from meteorological towers, remote-sensors, and radiosondes are used to simultaneously characterize surface fluxes, atmospheric structure, cloud properties, in-cloud motions, and the depth of the cloud-driven mixed layer in multiple Arctic environments. Relationships among these parameters are explored to elucidate the properties of the system that determine the degree of vertical atmospheric mixing and the coupling state between cloud and surface. The influence of temperature and moisture inversions on this system is also explored. Transitions in the coupling state are utilized to illustrate the relative roles of different processes. Cases from a coastal Arctic site at Barrow, Alaska and a station embedded in the Arctic sea-ice pack are used to contrast conditional influences related to season and surface type. It is found that over sea-ice, where surface turbulent fluxes are weak, the coupling of cloud-level processes to the surface layer is largely due to proximity of the cloud-driven mixed layer to the surface, which appears to be primarily influenced by

  18. Characterization of carbides composite surface layers produced by PTA

    NASA Astrophysics Data System (ADS)

    Tajoure, M.; Tajouri, A.

    2015-03-01

    Composite surface layer of nickel base with titanium carbide in powder form was deposited on to surface of low alloy steel 18G2A type according to polish standard by using plasma transferred arc technique. Results showed that, plasma transferred arc hardfacin process was successfully conducted by using PMNICr50P alloy plus titanium carbide powders. Maximum hardness of 754 HV and minimum dilution of 4.6 % were achieved by using an arc current of 80 A. However, when the current was further increased to 120 A& the dilution increases with current increase while the hardness decreases. Microstructure of the nickel base with titanium carbide feature uniform distribution of reinforcement particles with irregular grain shape and relatively small particles size, and regular boundary line between the substrate and over layer with presence of black area along the boundary line. A few micro - porosities are located in the matrix.

  19. On the Effects of Surface Roughness on Boundary Layer Transition

    NASA Technical Reports Server (NTRS)

    Choudhari, Meelan M.; Li, Fei; Chang, Chau-Lyan; Edwards, Jack

    2009-01-01

    Surface roughness can influence laminar-turbulent transition in many different ways. This paper outlines selected analyses performed at the NASA Langley Research Center, ranging in speed from subsonic to hypersonic Mach numbers and highlighting the beneficial as well as adverse roles of the surface roughness in technological applications. The first theme pertains to boundary-layer tripping on the forebody of a hypersonic airbreathing configuration via a spanwise periodic array of trip elements, with the goal of understanding the physical mechanisms underlying roughness-induced transition in a high-speed boundary layer. The effect of an isolated, finite amplitude roughness element on a supersonic boundary layer is considered next. The other set of flow configurations examined herein corresponds to roughness based laminar flow control in subsonic and supersonic swept wing boundary layers. A common theme to all of the above configurations is the need to apply higher fidelity, physics based techniques to develop reliable predictions of roughness effects on laminar-turbulent transition.

  20. Rotating compact bodies with a disk surface layer

    NASA Astrophysics Data System (ADS)

    Haggag, Salah

    2016-03-01

    The Senovilla family for a subclass of Petrov type-D stationary axisymmetric differentially rotating perfect fluids is considered. A scheme is presented to construct from a solution an interior of a rotating compact body satisfying dominant energy conditions and with a boundary of vanishing pressure. The equatorial disk of the body is a surface layer due to a jump in the second fundamental form. However, unlike previous results, the body is free from curvature singularities.

  1. Surface-plasmons lasing in double-graphene-layer structures

    SciTech Connect

    Dubinov, A. A.; Aleshkin, V. Ya.; Ryzhii, V.; Shur, M. S.; Otsuji, T.

    2014-01-28

    We consider the concept of injection terahertz lasers based on double-graphene-layer (double-GL) structures with metal surface-plasmon waveguide and study the conditions of their operation. The laser under consideration exploits the resonant radiative transitions between GLs. This enables the double-GL laser room temperature operation and the possibility of voltage tuning of the emission spectrum. We compare the characteristics of the double-GL lasers with the metal surface-plasmon waveguides with those of such laser with the metal-metal waveguides.

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

    PubMed

    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

  3. 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

  4. Efficient killing of inhaled bacteria in DeltaF508 mice: role of airway surface liquid composition.

    PubMed

    McCray, P B; Zabner, J; Jia, H P; Welsh, M J; Thorne, P S

    1999-07-01

    Cystic fibrosis mice have been generated by gene targeting but show little lung disease without repeated exposure to bacteria. We asked if murine mucosal defenses and airway surface liquid (ASL) Cl(-) were altered by the DeltaF508 cystic fibrosis transmembrane conductance regulator mutation. Naive DeltaF508 -/- and +/- mice showed no pulmonary inflammation and after inhaled Pseudomonas aeruginosa had similar inflammatory responses and bacterial clearance rates. We therefore investigated components of the innate immune system. Bronchoalveolar lavage fluid from mice killed Escherichia coli, and the microbicidal activity was inhibited by NaCl. Because beta-defensins are salt-sensitive epithelial products, we looked for pulmonary beta-defensin expression. A mouse homolog of human beta-defensin-1 (termed "MBD-1") was identified; the mRNA was expressed in the lung. Using a radiotracer technique, ASL volume and Cl(-) concentration ([Cl(-)]) were measured in cultured tracheal epithelia from normal and DeltaF508 -/- mice. The estimated ASL volume was similar for both groups. There were no differences in ASL [Cl(-)] in DeltaF508 -/- and normal mice (13.8 +/- 2.6 vs. 17.8 +/- 5.6 meq/l). Because ASL [Cl(-)] is low in normal and mutant mice, salt-sensitive antimicrobial factors, including MBD-1, may be normally active. PMID:10409246

  5. Moored surface buoy observations of the diurnal warm layer

    NASA Astrophysics Data System (ADS)

    Prytherch, J.; Farrar, J. T.; Weller, R. A.

    2013-09-01

    An extensive data set is used to examine the dynamics of diurnal warming in the upper ocean. The data set comprises more than 4700 days of measurements at five sites in the tropics and subtropics, obtained from surface moorings equipped to make comprehensive meteorological, incoming solar and infrared radiation, and high-resolution subsurface temperature (and, in some cases, velocity) measurements. The observations, which include surface warmings of up to 3.4°C, are compared with a selection of existing models of the diurnal warm layer (DWL). A simple one-layer physical model is shown to give a reasonable estimate of both the magnitude of diurnal surface warming (model-observation correlation 0.88) and the structure and temporal evolution of the DWL. Novel observations of velocity shear obtained during 346 days at one site, incorporating high-resolution (1 m) upper ocean (5-15 m) acoustic Doppler current profile measurements, are also shown to be in reasonable agreement with estimates from the physical model (daily maximum shear model-observation correlation 0.77). Physics-based improvements to the one-layer model (incorporation of rotation and freshwater terms) are discussed, though they do not provide significant improvements against the observations reported here. The simplicity and limitations of the physical model are used to discuss DWL dynamics. The physical model is shown to give better model performance under the range of forcing conditions experienced across the five sites than the more empirical models.

  6. Surface-cooling effects on compressible boundary-layer instability

    NASA Technical Reports Server (NTRS)

    Seddougui, Sharon O.; Bowles, R. I.; Smith, F. T.

    1990-01-01

    The influence of surface cooling on compressible boundary layer instability is discussed theoretically for both viscous and inviscid modes, at high Reynolds numbers. The cooling enhances the surface heat transfer and shear stress, creating a high heat transfer sublayer. This has the effect of distorting and accentuating the viscous Tollmien-Schlichting modes to such an extent that their spatial growth rates become comparable with, and can even exceed, the growth rates of inviscid modes, including those found previously. This is for moderate cooling, and it applies at any Mach number. In addition, the moderate cooling destabilizes otherwise stable viscous or inviscid modes, in particular triggering outward-traveling waves at the edge of the boundary layer in the supersonic regime. Severe cooling is also discussed as it brings compressible dynamics directly into play within the viscous sublayer. All the new cooled modes found involve the heat transfer sublayer quite actively, and they are often multi-structured in form and may be distinct from those observed in previous computational and experimental investigations. The corresponding nonlinear processes are also pointed out with regard to transition in the cooled compressible boundary layer. Finally, comparisons with Lysenko and Maslov's (1984) experiments on surface cooling are presented.

  7. Laser-Based Transient Surface Acceleration of Thermoelastic Layers

    NASA Astrophysics Data System (ADS)

    CETINKAYA, CETIN; WU, CUNLI; LI, CHEN

    2000-03-01

    The removal of particles from elastic substrates has been an important practical problem in the electronics industry especially as the sizes of electronic units shrink. In recent years, there has been an interest in removingsubmicron level particles from surfaces. The use of traditional surface cleaning methods, such as ultrasonically induced fluid flow, vibrational methods, centrifugal techniques, is limited to particles that require surface acceleration lower than 107m/s2. For the effective removal of submicron particles, a higher level surface acceleration is needed since the adhesion forces (mainly van der Waals force for dry surfaces) are related to the particle size and increase approximately linearly as the characteristic radius of small particles that are to be removed decreases. In current work, based on the generalized dynamic theory of thermoelasticity reported, a transfer matrix formulation including the second sound effect is developed for a thermoelastic layer. The transfer matrix for axisymmetric wave propagation in a thermoelastic layer is obtained by adopting a double integral transform approach. The second sound effect is included to eliminate the thermal wave travelling with infinite velocity as predicted by the diffusion heat transfer model, and, consequently, the immediate arrival of waves. Using the current formulation and the periodic systems framework, a transfer function formulation for calculating the accelerations is developed for transient analysis. A double integral transform inversion method is used for transient response calculations. Acceleration levels, sufficient for submicron particle removal, are reported. Various processes such as thermoelastic stresses, surface evaporation, and optical breakdown may be responsible for surface acceleration components and particle removal. In current work, only the surface acceleration due to transient thermoelastic wave propagation is under investigation.

  8. Tailored surface engineering of pigments by layer-by-layer coating.

    PubMed

    Dähne, Lars; Schneider, Julia; Lewe, Dirk; Petersen, Henrik

    2015-01-01

    We have evaluated the feasibility of layer-by-layer encapsulation technology for the improvement of dye pigments used for tattoos or permanent make-up. The formation of core-shell structures is possible by coating pigments with thin films of several different polyelectrolytes using this technology. The physicochemical surface properties, such as charge density and chemical functionality, can be reproducibly varied in a wide range. Tailoring the surface properties independently from the pigment core allows one to control the rheological behaviour of pigment suspensions, to prevent aggregation between different pigments, to reduce the cytotoxicity, and to influence the response of phagocytes in order to have similar or the same uptake and bioclearance for all pigments. These properties determine the durability and colour tone stability of tattoos and permanent make-up. PMID:25833634

  9. Turbulence effects on concentration statistics in the atmospheric surface layer

    SciTech Connect

    Biltoft, C.; Bowers, J.; Yee, E.; Klewicki, J.; Metzger, M.

    1996-12-31

    The dispersion of windborne material released near the earth`s surface is strongly influenced by this impenetrable boundary, which inhibits downward mixing and creates sharp vertical gradients in wind, temperature, turbulence. These strong gradients and the continuous creation of turbulence at the surface cause a rapid evolution of the vertical concentration structure for material released into the atmospheric surface layer (ASL). Recent developments in fast-response instrumentation and an increased realization of potential hazards from the release of common industrial chemicals into the ASL have led to a series of tripartite (US, UK, Canada) field experiments at the US Army Dugway Proving Ground, Utah. This paper contains a preliminary analysis of the data from the most recent follow-on experiments, which included measurements of the vertical profiles of mean and peak concentrations.

  10. Nucleotide-mediated airway clearance.

    PubMed

    Schmid, Andreas; Clunes, Lucy A; Salathe, Mathias; Verdugo, Pedro; Dietl, Paul; Davis, C William; Tarran, Robert

    2011-01-01

    A thin layer of airway surface liquid (ASL) lines the entire surface of the lung and is the first point of contact between the lung and the environment. Surfactants contained within this layer are secreted in the alveolar region and are required to maintain a low surface tension and to prevent alveolar collapse. Mucins are secreted into the ASL throughout the respiratory tract and serve to intercept inhaled pathogens, allergens and toxins. Their removal by mucociliary clearance (MCC) is facilitated by cilia beating and hydration of the ASL by active ion transport. Throughout the lung, secretion, ion transport and cilia beating are under purinergic control. Pulmonary epithelia release ATP into the ASL which acts in an autocrine fashion on P2Y(2) (ATP) receptors. The enzymatic network describes in Chap. 2 then mounts a secondary wave of signaling by surface conversion of ATP into adenosine (ADO), which induces A(2B) (ADO) receptor-mediated responses. This chapter offers a comprehensive description of MCC and the extensive ramifications of the purinergic signaling network on pulmonary surfaces. PMID:21560046

  11. Linear stability of a layered fluid with mobile surface plates

    NASA Technical Reports Server (NTRS)

    Buffett, B. A.; Gable, C. W.; O'Connell, R. J.

    1994-01-01

    We develop a general method of calculating the linear stability of a fluid with homogeneous layers that is heated from below. The method employs a propagator technique to obtain expressions for the fluid velocity, stress, and temperature. The principal advantage of the method is the ease with which solutions are adapted to a wide variety of boundary conditions and fluid properties. We demonstrate the utility of the method using three examples which quantify the effects of (1) rheological layering, (2) mobile plates at the surface, and (3) multiple phase transitions. Each example is presented in the context of Earth's mantle. In the first example, we predict that convection becomes confined to the upper mantle once the viscosity increase between the upper and lower mantle exceeds a factor of 2000, consistent with the nonlinear calculations of Davies (1977). In the second example we find that the heat flux variations in a convecting fluid with variably sized, surface plates can be attributed, in part, to changes in the critical Rayleigh number. The linear stability of a fluid with multiple phase transitions is significantly affects by the locations of the transitions. We find that phase transitions have their largest effect when they are located at the center of the fluid layer and become much less important when they are located near the exterior boundaries.

  12. Multi-layer topological transmissions of spoof surface plasmon polaritons.

    PubMed

    Pan, Bai Cao; Zhao, Jie; Liao, Zhen; Zhang, Hao Chi; Cui, Tie Jun

    2016-01-01

    Spoof surface plasmon polaritons (SPPs) in microwave frequency provide a high field confinement in subwavelength scale and low-loss and flexible transmissions, which have been widely used in novel transmission waveguides and functional devices. To play more important roles in modern integrated circuits and systems, it is necessary and helpful for the SPP modes to propagate among different layers of devices and chips. Owing to the highly confined property and organized near-field distribution, we show that the spoof SPPs could be easily transmitted from one layer into another layer via metallic holes and arc-shaped transitions. Such designs are suitable for both the ultrathin and flexible single-strip SPP waveguide and double-strip SPP waveguide for active SPP devices. Numerical simulations and experimental results demonstrate the broadband and high-efficiency multi-layer topological transmissions with controllable absorption that is related to the superposition area of corrugated metallic strips. The transmission coefficient of single-strip SPP waveguide is no worse than -0.8 dB within frequency band from 2.67 GHz to 10.2 GHz while the transmission of double-strip SPP waveguide keeps above -1 dB within frequency band from 2.26 GHz to 11.8 GHz. The proposed method will enhance the realizations of highly complicated plasmonic integrated circuits. PMID:26939995

  13. Multi-layer topological transmissions of spoof surface plasmon polaritons

    PubMed Central

    Pan, Bai Cao; Zhao, Jie; Liao, Zhen; Zhang, Hao Chi; Cui, Tie Jun

    2016-01-01

    Spoof surface plasmon polaritons (SPPs) in microwave frequency provide a high field confinement in subwavelength scale and low-loss and flexible transmissions, which have been widely used in novel transmission waveguides and functional devices. To play more important roles in modern integrated circuits and systems, it is necessary and helpful for the SPP modes to propagate among different layers of devices and chips. Owing to the highly confined property and organized near-field distribution, we show that the spoof SPPs could be easily transmitted from one layer into another layer via metallic holes and arc-shaped transitions. Such designs are suitable for both the ultrathin and flexible single-strip SPP waveguide and double-strip SPP waveguide for active SPP devices. Numerical simulations and experimental results demonstrate the broadband and high-efficiency multi-layer topological transmissions with controllable absorption that is related to the superposition area of corrugated metallic strips. The transmission coefficient of single-strip SPP waveguide is no worse than −0.8 dB within frequency band from 2.67 GHz to 10.2 GHz while the transmission of double-strip SPP waveguide keeps above −1 dB within frequency band from 2.26 GHz to 11.8 GHz. The proposed method will enhance the realizations of highly complicated plasmonic integrated circuits. PMID:26939995

  14. Summer surface layer thermal response to surface gravity waves in the Yellow Sea

    NASA Astrophysics Data System (ADS)

    Zhang, Xuefeng; Han, Guijun; Wang, Dongxiao; Deng, Zengan; Li, Wei

    2012-07-01

    The Princeton Ocean Model (POM) with generalized coordinate system (POMgcs) is used to study the summer surface-layer thermal response to surface gravity waves in the Yellow Sea (YS). The parameterization schemes of wave breaking developed by Mellor and Blumberg (J Phys Oceanogr 34:693-698, 2004) and Kantha and Clayson (Ocean Model 6:101-124, 2004), respectively, and Stokes production developed by Kantha and Clayson (Ocean Model 6:101-124, 2004) are both included in the Mellor-Yamada turbulence closure model Mellor and Yamada (Rev Geophys 20:851-875, 1982) of POMgcs. Numerical results show that surface gravity waves impact the depth of surface mixed layer of temperature in the YS in summer. The surface mixed layer in the YS cannot be reproduced well and has a visible difference from the observation if the parameterization schemes are not included. A diagnostic analysis of turbulent kinetic energy suggests that both Stokes production and wave breaking play key roles in enhancing the turbulent mixing near the sea surface in the YS. Stokes production seems to have a greater impact throughout the upper mixed layer in the YS in summer than that of wave breaking. In addition, a diagnostic analysis of the momentum balance shows that Coriolis-Stokes forcing has a significant effect on the momentum budget in the upper layer in the YS, and surface gravity waves are able to reduce the velocity of mean flow near the surface and make the mean flow near the surface more homogeneous vertically in the YS.

  15. Soil moisture sensor calibration for organic soil surface layers

    NASA Astrophysics Data System (ADS)

    Bircher, S.; Andreasen, M.; Vuollet, J.; Vehviläinen, J.; Rautiainen, K.; Jonard, F.; Weihermüller, L.; Zakharova, E.; Wigneron, J.-P.; Kerr, Y. H.

    2015-12-01

    This paper's objective is to present generic calibration functions for organic surface layers derived for the soil moisture sensors Decagon ECH2O 5TE and Delta-T ThetaProbe ML2x, using material from northern regions, mainly from the Finish Meteorological Institute's Arctic Research Center in Sodankylä and the study area of the Danish Center for Hydrology HOBE. For the Decagon 5TE sensor such a function is currently not reported in literature. Data were compared with measurements from underlying mineral soils including laboratory and field measurements. Shrinkage and charring during drying were considered. For both sensors all field and lab data showed consistent trends. For mineral layers with low soil organic matter (SOM) content the validity of the manufacturer's calibrations was demonstrated. Deviating sensor outputs in organic and mineral horizons were identified: for the Decagon 5TE apparent relative permittivities at a given moisture content decreased for increased SOM content, which was attributed to an increase of bound water in organic materials with large surface areas compared to the studied mineral soils. ThetaProbe measurements from organic horizons showed stronger non-linearity in the sensor response and signal saturation in the high level data. The derived calibration fit functions between sensor response and volumetric water content hold for samples spanning a wide range of humus types with differing SOM characteristics. This strengthens confidence in their validity under various conditions, rendering them highly suitable for large-scale applications in remote sensing and land surface modeling studies. Agreement between independent Decagon 5TE and ThetaProbe time series from an organic surface layer at the Sodankylä site was significantly improved when the here proposed fit functions were used. Decagon 5TE data also well-reflected precipitation events. Thus, Decagon 5TE network data from organic surface layers at the Sodankylä and HOBE sites are

  16. Soil moisture sensor calibration for organic soil surface layers

    NASA Astrophysics Data System (ADS)

    Bircher, Simone; Andreasen, Mie; Vuollet, Johanna; Vehviläinen, Juho; Rautiainen, Kimmo; Jonard, François; Weihermüller, Lutz; Zakharova, Elena; Wigneron, Jean-Pierre; Kerr, Yann H.

    2016-04-01

    This paper's objective is to present generic calibration functions for organic surface layers derived for the soil moisture sensors Decagon ECH2O 5TE and Delta-T ThetaProbe ML2x, using material from northern regions, mainly from the Finnish Meteorological Institute's Arctic Research Center in Sodankylä and the study area of the Danish Center for Hydrology (HOBE). For the Decagon 5TE sensor such a function is currently not reported in the literature. Data were compared with measurements from underlying mineral soils including laboratory and field measurements. Shrinkage and charring during drying were considered. For both sensors all field and lab data showed consistent trends. For mineral layers with low soil organic matter (SOM) content the validity of the manufacturer's calibrations was demonstrated. Deviating sensor outputs in organic and mineral horizons were identified. For the Decagon 5TE, apparent relative permittivities at a given moisture content decreased for increased SOM content, which was attributed to an increase of bound water in organic materials with large specific surface areas compared to the studied mineral soils. ThetaProbe measurements from organic horizons showed stronger nonlinearity in the sensor response and signal saturation in the high-level data. The derived calibration fit functions between sensor response and volumetric water content hold for samples spanning a wide range of humus types with differing SOM characteristics. This strengthens confidence in their validity under various conditions, rendering them highly suitable for large-scale applications in remote sensing and land surface modeling studies. Agreement between independent Decagon 5TE and ThetaProbe time series from an organic surface layer at the Sodankylä site was significantly improved when the here-proposed fit functions were used. Decagon 5TE data also well-reflected precipitation events. Thus, Decagon 5TE network data from organic surface layers at the Sodankylä and

  17. Atmospheric surface and boundary layers of the Amazon Basin

    NASA Technical Reports Server (NTRS)

    Garstang, Michael

    1987-01-01

    Three phases of work were performed: design of and preparation for the Amazon Boundary Layer Experiment (ABLE 2-A); execution of the ABLE 2-A field program; and analysis of the ABLE 2-A data. Three areas of experiment design were dealt with: surface based meteorological measurements; aircraft missions; and project meteorological support. The primary goal was to obtain a good description of the structure of the atmosphere immediately above the rain forest canopy (top of canopy to a few thousand meters), to describe this region during the growing daytime phase of the boundary layer; and to examine the nighttime stratified state. A secondary objective was to examine the role that deep convective storms play in the vertical transport of heat, water vapor, and other trace gases. While significant progress was made, much of the analysis remains to be done.

  18. Site of Fluid Secretion in Small Airways.

    PubMed

    Flores-Delgado, Guillermo; Lytle, Christian; Quinton, Paul M

    2016-03-01

    The secretion and management of readily transportable airway surface liquid (ASL) along the respiratory tract is crucial for the clearance of debris and pathogens from the lungs. In proximal large airways, submucosal glands (SMGs) can produce ASL. However, in distal small airways, SMGs are absent, although the lumens of these airways are, uniquely, highly plicated. Little is known about the production and maintenance of ASL in small airways, but using electrophysiology, we recently found that native porcine small airways simultaneously secrete and absorb. How these airways can concurrently transport ASL in opposite directions is puzzling. Using high expression of the Na-K-2Cl cotransport (NKCC) 1 protein (SLC12a2) as a phenotypic marker for fluid secretory cells, immunofluorescence microscopy of porcine small airways revealed two morphologically separated sets of luminal epithelial cells. NKCC1 was abundantly expressed by most cells in the contraluminal regions of the pleats but highly expressed very infrequently by cells in the luminal folds of the epithelial plications. In larger proximal airways, the acini of SMGs expressed NKCC1 prominently, but cells expressing NKCC1 in the surface epithelium were sparse. Our findings indicate that, in the small airway, cells in the pleats of the epithelium secrete ASL, whereas, in the larger proximal airways, SMGs mainly secrete ASL. We propose a mechanism in which the locations of secretory cells in the base of pleats and of absorptive cells in luminal folds physically help maintain a constant volume of ASL in small airways. PMID:26562629

  19. Seaglider observations of surface mixed layer physics and biogeochemistry

    NASA Astrophysics Data System (ADS)

    Damerell, Gillian; Heywood, Karen; Thompson, Andrew; Henson, Stephanie; Rumyantseva, Anya

    2013-04-01

    The Ocean Surface Mixing, Ocean Sub-mesoscale Interaction Study (OSMOSIS) aims to develop new, physically-based parameterisations of processes that deepen and shoal the ocean surface boundary layer. As part of this project, 2 Seagliders were deployed in September 2012 at the Porcupine Abyssal Plain (PAP) site in the North Atlantic, to measure the structure and evolution of the ocean surface boundary layer over the seasonal cycle. The gliders measured temperature, salinity, dissolved oxygen, dive-averaged currents, chlorophyll fluorescence, CDOM fluorescence and PAR. We present results from the first 6 months of the Seaglider deployments, examining particular case studies of deepening/shoaling events and their impact on the biogeochemistry. Shoaling events appear to be more abrupt than deepening events. We also discuss the water masses found in the area, in particular, the occurrences of Mediterranean Water observed at a depth of approximately 800 m. As a contribution to the GROOM project, we assess the advantages and challenges of maintaining a continuous glider-based multidisciplinary observing system at the PAP site, with 2 gliders being turned around approximately every 4 months.

  20. Oblique surface Josephson plasma waves in layered superconductors

    NASA Astrophysics Data System (ADS)

    Averkov, Yu. O.; Yakovenko, V. M.; Yampol'skii, V. A.; Nori, Franco

    2013-02-01

    We have theoretically studied oblique surface waves (OSWs) which propagate along the interface between a dielectric and a layered superconductor. We assume that this interface is perpendicular to the superconducting layers, and OSWs at the interface can propagate at an arbitrary angle with respect to them. The electromagnetic field of the OSWs in a layered superconductor is a superposition of an ordinary wave (with its electric field parallel to the layers) and an extraordinary wave (with its magnetic field parallel to the layers). We have derived the dispersion equation for the OSWs and shown that the dispersion curves have end points where the extraordinary mode transforms from evanescent wave to bulk wave, propagating deep into the superconductor. In addition, we have analytically solved the problem of the resonance excitation of the OSWs by the attenuated-total-reflection method using an additional dielectric prism. Due to the strong current anisotropy in the boundary of the superconductor, the excitation of the OSWs is accompanied by an additional important phenomenon: The electromagnetic field component with the orthogonal polarization appears in the wave reflected from the bottom of the prism. We show that, for definite optimal combinations of the problem parameters (the wave frequency, the direction of the incident wave vector, the thickness of the gap between dielectric prism and superconductor, etc.), there is a complete suppression of the reflected wave with its polarization coinciding with the polarization of the incident wave. Contrary to the isotropic case, this phenomenon can be observed even in the dissipationless limit. In such a regime, the complete transformation of the incident wave into a reflected wave with orthogonal polarization can be observed.

  1. Characteristics of turbulent structures in the unstable atmospheric surface layer

    NASA Astrophysics Data System (ADS)

    Schols, J. L. J.; Jansen, A. E.; Krom, J. G.

    1985-10-01

    An atmospheric surface-layer (ASL) experiment conducted at a meteorological site in the Oostelijk-Flevoland polder of the Netherlands is described. Turbulent fluctuations of wind velocity, air temperature and static pressure were measured, using three 10 m towers. Simultaneous turbulent signals at several heights on the towers were used to investigate the properties of the turbulent structures which contribute most significantly to the turbulent vertical transports in the unstable ASL. These turbulent structures produce between 30 and 50% of the mean turbulent vertical transport of horizontal alongwind momentum and they contribute to between 40 and 50% of the mean turbulent vertical heat transport; in both cases this occurs during 15 to 20% of the total observation time. The translation speed of the turbulent structures equals the wind speed averaged over the depth of the ASL, which scales on the surface friction velocity. The inclination angle of the temperature interface at the upstream edge of the turbulent structures to the surface is significantly smaller than that of the internal shear layer, which is associated with the temperature interface. The turbulent structures in the unstable ASL are determined by a large-scale temperature field: Convective motions, which encompass the whole depth of the planetary boundary layer (PBL), penetrate into the ASL. The curvature of the vertical profile of mean horizontal alongwind velocity forces the alignment of the convective cells in the flow direction (Kuettner, 1971), which have an average length of several hundreds of metres and an average width of a few tens of metres. This mechanism leads to the formation of turbulent structures, which extend throughout the depth of the ASL.

  2. Surface activation of CNT Webs towards layer by layer assembly of biosensors.

    PubMed

    Musameh, Mustafa; Huynh, Chi P; Hickey, Mark; Kyratzis, Ilias Louis

    2016-04-25

    Several surface activation methods such as chemical, electrochemical and plasma have been used for enhancing the electrochemical performance of carbon based electrodes for various applications. However, some of these surface activation methods may not be useful depending on the chemical and physical properties of the activated surface. Herein we investigate the surface activation of carbon nanotube (CNT) webs by electrochemical and plasma techniques to enhance their electrochemical performance and enable the fabrication of a biosensor using the layer-by-layer (LBL) approach. The pretreated CNT webs were characterized by SEM, TEM, Raman, XPS and electrochemical methods. TEM images and Raman analysis showed an increase in the level of surface defects upon pretreatment with higher number of defects after electrochemical pretreatment. XPS analysis showed an increase in the level of oxygen functional groups after pretreatment (4 to 5 times increase) which resulted in enhanced water wettability especially for plasma pretreated CNT webs. The pretreated CNT web electrodes also showed an enhanced electrochemical activity towards the oxidation and reduction of different redox probes with higher sensitivity for the electrochemically pretreated CNT web electrode that was accompanied by a higher level of noise in amperometric measurements. A highly linear response was obtained for the untreated and the electrochemically pretreated CNT web electrodes towards the amperometric detection of NADH (R(2) of 0.9996 and 0.9986 respectively) while a non-linear response was observed for the plasma pretreated CNT web electrode (R(2) of 0.8538). The pretreated CNT web electrodes enabled the fabrication of a LBL biosensor for alcohol detection with highest operational stability obtained for the plasma pretreated CNT web surface. PMID:26818435

  3. Boundary layer flow of nanofluid over an exponentially stretching surface

    PubMed Central

    2012-01-01

    The steady boundary layer flow of nanofluid over an exponential stretching surface is investigated analytically. The transport equations include the effects of Brownian motion parameter and thermophoresis parameter. The highly nonlinear coupled partial differential equations are simplified with the help of suitable similarity transformations. The reduced equations are then solved analytically with the help of homotopy analysis method (HAM). The convergence of HAM solutions are obtained by plotting h-curve. The expressions for velocity, temperature and nanoparticle volume fraction are computed for some values of the parameters namely, suction injection parameter α, Lewis number Le, the Brownian motion parameter Nb and thermophoresis parameter Nt. PMID:22289390

  4. Systems-level airway models of bronchoconstriction.

    PubMed

    Donovan, Graham M

    2016-09-01

    Understanding lung and airway behavior presents a number of challenges, both experimental and theoretical, but the potential rewards are great in terms of both potential treatments for disease and interesting biophysical phenomena. This presents an opportunity for modeling to contribute to greater understanding, and here, we focus on modeling efforts that work toward understanding the behavior of airways in vivo, with an emphasis on asthma. We look particularly at those models that address not just isolated airways but many of the important ways in which airways are coupled both with each other and with other structures. This includes both interesting phenomena involving the airways and the layer of airway smooth muscle that surrounds them, and also the emergence of spatial ventilation patterns via dynamic airway interaction. WIREs Syst Biol Med 2016, 8:459-467. doi: 10.1002/wsbm.1349 For further resources related to this article, please visit the WIREs website. PMID:27348217

  5. Epitaxially guided assembly of collagen layers on mica surfaces.

    PubMed

    Leow, Wee Wen; Hwang, Wonmuk

    2011-09-01

    Ordered assembly of collagen molecules on flat substrates has potential for various applications and serves as a model system for studying the assembly process. While previous studies demonstrated self-assembly of collagen on muscovite mica into highly ordered layers, the mechanism by which different conditions affect the resulting morphology remains to be elucidated. Using atomic force microscopy, we follow the assembly of collagen on muscovite mica at a concentration lower than the critical fibrillogenesis concentration in bulk. Initially, individual collagen molecules adsorb to mica and subsequently nucleate into fibrils possessing the 67 nm D-periodic bands. Emergence of fibrils aligned in parallel despite large interfibril distances agrees with an alignment mechanism guided by the underlying mica. The epitaxial growth was further confirmed by the formation of novel triangular networks of collagen fibrils on phlogopite mica, whose surface lattice is known to have a hexagonal symmetry, whereas the more widely used muscovite does not. Comparing collagen assembly on the two types of mica at different potassium concentrations revealed that potassium binds to the negatively charged mica surface and neutralizes it, thereby reducing the binding affinity of collagen and enhancing surface diffusion. These results suggest that collagen assembly on mica follows the surface adsorption, diffusion, nucleation, and growth pathway, where the growth direction is determined at the nucleation step. Comparison with other molecules that assemble similarly on mica supports generality of the proposed assembly mechanism, the knowledge of which will be useful for controlling the resulting surface morphologies. PMID:21740026

  6. Molecular orientation of rhodamine dyes on surfaces of layered silicates.

    PubMed

    Bujdák, Juraj; Iyi, Nobuo

    2005-03-17

    Films of the layered silicates fluorohectorite (FH) and saponite (Sap) with various rhodamine dyes were prepared. The dyes with acidic as well as large hydrophobic groups in their molecule were not adsorbed on the surface of FH, which was interpreted in terms of high charge density on the surface of this silicate. All adsorbed dyes formed similar forms, such as isolated cations and H-type molecular aggregates, which were characterized by different spectral properties. Polarized ultraviolet-visible (UV-vis) spectroscopy was used for the characterization of the molecular orientation of dye chromophores on the silicate surface. The isolated dye cations and species, which absorbed light at the low energy part of the spectra, were only slightly tilted with respect to the plane of the silicate surface. The cations forming H-aggregates and absorbing light at low wavelengths were oriented in a nearly perpendicular fashion. The nearly perpendicular orientation was observed as a strong increase of dichroic ratio with film tilting. The orientation of the cations in H-aggregates depends partially on the structure of the dye molecule, namely, on the type of amino group (primary, secondary, or tertiary) in the dye molecule. The type of amino groups probably plays a role in the suitable orientation of dye cations for effective electrostatic interaction between the cations and the negatively charged siloxane surface. X-ray powder diffraction could not distinguish dye phases of dye monomers and molecular aggregates. PMID:16851539

  7. Nanofilms of hyaluronan/chitosan assembled layer-by-layer: An antibacterial surface for Xylella fastidiosa.

    PubMed

    Hernández-Montelongo, Jacobo; Nascimento, Vicente F; Murillo, Duber; Taketa, Thiago B; Sahoo, Prasana; de Souza, Alessandra A; Beppu, Marisa M; Cotta, Monica A

    2016-01-20

    In this work, nanofilms of hyaluronan/chitosan (HA/CHI) assembled layer by layer were synthesized; their application as a potential antimicrobial material was demonstrated for the phytopathogen Xylella fastidiosa, a gram-negative bacterium, here used as a model. For the synthesis, the influence of pH and ionic strength of these natural polymer stem-solutions on final characteristics of the HA/CHI nanofilms was studied in detail. The antibacterial effect was evaluated using widefield fluorescence microscopy. These results were correlated with the chemical properties of the nanofilms, studied by FTIR and Raman spectroscopy, as well as with their morphology and surface properties characterized using SEM and AFM. The present findings can be extended to design and optimize HA/CHI nanofilms with enhanced antimicrobial behavior for other type of phytopathogenic gram-negative bacteria species, such as Xanthomonas citri, Xanthomas campestri and Ralstonia solanacearum. PMID:26572322

  8. Trapping surface electrons on graphene layers and islands

    NASA Astrophysics Data System (ADS)

    Niesner, D.; Fauster, Th.; Dadap, J. I.; Zaki, N.; Knox, K. R.; Yeh, P.-C.; Bhandari, R.; Osgood, R. M.; Petrović, M.; Kralj, M.

    2012-02-01

    We report the use of time- and angle-resolved two-photon photoemission to map the bound, unoccupied electronic structure of the weakly coupled graphene/Ir(111) system. The energy, dispersion, and lifetime of the lowest three image-potential states are measured. In addition, the weak interaction between Ir and graphene permits observation of resonant transitions from an unquenched Shockley-type surface state of the Ir substrate to graphene/Ir image-potential states. The image-potential-state lifetimes are comparable to those of midgap clean metal surfaces. Evidence of localization of the excited electrons on single-atom-layer graphene islands is provided by coverage-dependent measurements.

  9. Layer by Layer, Nano-particle "Only" Surface Modification of Filtration Membranes

    NASA Astrophysics Data System (ADS)

    Escobar-Ferrand, Luis

    Layer by Layer (LbL) deposition using primarily inorganic silica nanoparticles is employed for the modification of polymeric micro and ultrafiltration (MF/UF) membranes to produce thin film composites (TFC) with potential nanofiltration (NF) and reverse osmosis (RO) capabilities.. A variety of porous substrate membranes with different membrane surface characteristics are employed, but exhibiting in common that wicking of water does not readily occur into the pore structure, including polycarbonate track etched (PCTE), polyethersulfone (PES) and sulfonated PES (SPEES) MF/UF membranes. Both spherical (cationic/anionic) and eccentric elongated (anionic) silica nanoparticles are deposited using conditions similar to those reported by Lee et al. Appropriate selection of the pH's for anionic and cationic particle deposition enables the construction of nanoparticle only layers 100--1200 nm in thickness atop the original membrane substrates. The surface layer thickness varies monotonically with the number of bilayers (anionic/cationic deposition cycles) as expected. The deposition process is optimized to eliminate drying induced cracking and to improve mechanical durability via thickness control and post-deposition hydro-thermal treatment. The hydrodynamic permeability of these TFC membranes is measured to evaluate their performance under typical NF operating conditions using dead-end permeation experiments and their performance compared quantitatively with realistic hydrodynamic models, with favorable results. For track etched polycarbonate MF substrates, surface modification causes a permeability reduction of approximately two orders of magnitude with respect to the bare substrates, to values comparable to those for typical commercial NF membranes. Good quantitative agreement with hydrodynamic models with no adjustable parameters was also established for this case, providing indirect confirmation that the LbL deposited surface layers are largely defect (crack) free

  10. In vivo Measurement of the Mouse Pulmonary Endothelial Surface Layer

    PubMed Central

    Yang, Yimu; Yang, Gaoqing; Schmidt, Eric P.

    2013-01-01

    The endothelial glycocalyx is a layer of proteoglycans and associated glycosaminoglycans lining the vascular lumen. In vivo, the glycocalyx is highly hydrated, forming a substantial endothelial surface layer (ESL) that contributes to the maintenance of endothelial function. As the endothelial glycocalyx is often aberrant in vitro and is lost during standard tissue fixation techniques, study of the ESL requires use of intravital microscopy. To best approximate the complex physiology of the alveolar microvasculature, pulmonary intravital imaging is ideally performed on a freely-moving lung. These preparations, however, typically suffer from extensive motion artifact. We demonstrate how closed-chest intravital microscopy of a freely-moving mouse lung can be used to measure glycocalyx integrity via ESL exclusion of fluorescently-labeled high molecular weight dextrans from the endothelial surface. This non-recovery surgical technique, which requires simultaneous brightfield and fluorescent imaging of the mouse lung, allows for longitudinal observation of the subpleural microvasculature without evidence of inducing confounding lung injury. PMID:23462690

  11. Thermal stability of nanocrystalline layers fabricated by surface nanocrystallization

    NASA Astrophysics Data System (ADS)

    Mai, Yong-jin; Jie, Xiao-hua; Liu, Li-li; Yu, Neng; Zheng, Xiang-xin

    2010-01-01

    A nanocrystalline layer with ultrafine grains (about 30-40 nm) on the surface of 7050 aluminum alloy was fabricated by a new technique called High Pressure Shot Peening (HPSP) which is the combination of common Shot Peening equipment with a pressurizing vessel. Relationship between hot flow and temperature was observed by Differential Scanning Calorimetry (DSC) and the activation energy, calculated by Kisssinger equation, of the as-treated sample increased 26.6 kJ/mol when it is compared with the as-reserved sample. The Bragg peaks of the as-prepared samples, respectively treated with various annealing treatments were characterized by XRD and the microhardness distribution along the depth from the treated surface were measured at the same time, which indicated that the broadening of Bragg peaks decreased with the increasing of anneal temperature; the grain size, calculated by Scherrer-Wilson equation, increased obviously during 180-220 °C, accordingly, the microhardness obviously decreased. According to the results of DSC, XRD and microhardness, it is reasonable to deduce that the temperature range of thermal stability for aluminum alloy nanocrystalline layer is lower than 200 °C.

  12. Atomic layer deposition of ultrathin platinum films on tungsten atomic layer deposition adhesion layers: Application to high surface area substrates

    SciTech Connect

    Clancey, Joel W.; Cavanagh, Andrew S.; Kukreja, Ratandeep S.; Kongkanand, Anusorn; George, Steven M.

    2015-01-15

    Platinum (Pt) atomic layer deposition (ALD) usually yields Pt nanoparticles during initial film growth. In contrast, deposition of continuous and ultrathin Pt films is needed for many important applications, such as the oxygen reduction reaction in polymer electrolyte membrane (PEM) fuel cells. A continuous and high radius of curvature Pt film is more stable and has a higher area-specific activity than the Pt nanoparticles commonly used in PEM fuel cells. However, the Pt film must be ultrathin and have a large surface area to be cost effective. In this paper, a review of earlier Pt ALD studies on flat substrates is presented that demonstrates that tungsten, with a higher surface energy than platinum, can serve as an adhesion layer to achieve Pt ALD films that are continuous at ultrathin thicknesses of ∼1.5 nm. This work utilized MeCpPtMe{sub 3} and H{sub 2} plasma as the Pt ALD reactants. The deposition of continuous and ultrathin Pt ALD films using MeCpPtMe{sub 3} and H{sub 2} plasma as the reactants is then studied on two high surface area substrate materials: TiO{sub 2} nanoparticles and 3M nanostructured thin film (NSTF). Transmission electron microscopy (TEM) showed uniform and continuous Pt films with thicknesses of ∼4 nm on the TiO{sub 2} nanoparticles. TEM with electron energy loss spectroscopy analysis revealed W ALD and Pt ALD films with thicknesses of ∼3 nm that were continuous and conformal on the high aspect ratio NSTF substrates. These results demonstrate that cost effective use of Pt ALD on high surface area substrates is possible for PEM fuel cells.

  13. pH modulates the activity and synergism of the airway surface liquid antimicrobials β-defensin-3 and LL-37

    PubMed Central

    Abou Alaiwa, Mahmoud H.; Reznikov, Leah R.; Gansemer, Nicholas D.; Sheets, Kelsey A.; Horswill, Alexander R.; Stoltz, David A.; Zabner, Joseph; Welsh, Michael J.

    2014-01-01

    The pulmonary airways are continuously exposed to bacteria. As a first line of defense against infection, the airway surface liquid (ASL) contains a complex mixture of antimicrobial factors that kill inhaled and aspirated bacteria. The composition of ASL is critical for antimicrobial effectiveness. For example, in cystic fibrosis an abnormally acidic ASL inhibits antimicrobial activity. Here, we tested the effect of pH on the activity of an ASL defensin, human β-defensin-3 (hBD-3), and the cathelicidin-related peptide, LL-37. We found that reducing pH from 8.0 to 6.8 reduced the ability of both peptides to kill Staphylococcus aureus. An acidic pH also attenuated LL-37 killing of Pseudomonas aeruginosa. In addition, we discovered synergism between hBD-3 and LL-37 in killing S. aureus. LL-37 and lysozyme were also synergistic. Importantly, an acidic pH reduced the synergistic effects of combinations of ASL antibacterials. These results indicate that an acidic pH reduces the activity of individual ASL antimicrobials, impairs synergism between them, and thus may disrupt an important airway host defense mechanism. PMID:25512526

  14. pH modulates the activity and synergism of the airway surface liquid antimicrobials β-defensin-3 and LL-37.

    PubMed

    Abou Alaiwa, Mahmoud H; Reznikov, Leah R; Gansemer, Nicholas D; Sheets, Kelsey A; Horswill, Alexander R; Stoltz, David A; Zabner, Joseph; Welsh, Michael J

    2014-12-30

    The pulmonary airways are continuously exposed to bacteria. As a first line of defense against infection, the airway surface liquid (ASL) contains a complex mixture of antimicrobial factors that kill inhaled and aspirated bacteria. The composition of ASL is critical for antimicrobial effectiveness. For example, in cystic fibrosis an abnormally acidic ASL inhibits antimicrobial activity. Here, we tested the effect of pH on the activity of an ASL defensin, human β-defensin-3 (hBD-3), and the cathelicidin-related peptide, LL-37. We found that reducing pH from 8.0 to 6.8 reduced the ability of both peptides to kill Staphylococcus aureus. An acidic pH also attenuated LL-37 killing of Pseudomonas aeruginosa. In addition, we discovered synergism between hBD-3 and LL-37 in killing S. aureus. LL-37 and lysozyme were also synergistic. Importantly, an acidic pH reduced the synergistic effects of combinations of ASL antibacterials. These results indicate that an acidic pH reduces the activity of individual ASL antimicrobials, impairs synergism between them, and thus may disrupt an important airway host defense mechanism. PMID:25512526

  15. Chronic effects of mechanical force on airways.

    PubMed

    Tschumperlin, Daniel J; Drazen, Jeffrey M

    2006-01-01

    Airways are embedded in the mechanically dynamic environment of the lung. In utero, this mechanical environment is defined largely by fluid secretion into the developing airway lumen. Clinical, whole lung, and cellular studies demonstrate pivotal roles for mechanical distention in airway morphogenesis and cellular behavior during lung development. In the adult lung, the mechanical environment is defined by a dynamic balance of surface, tissue, and muscle forces. Diseases of the airways modulate both the mechanical stresses to which the airways are exposed as well as the structure and mechanical behavior of the airways. For instance, in asthma, activation of airway smooth muscle abruptly changes the airway size and stress state within the airway wall; asthma also results in profound remodeling of the airway wall. Data now demonstrate that airway epithelial cells, smooth muscle cells, and fibroblasts respond to their mechanical environment. A prominent role has been identified for the epithelium in transducing mechanical stresses, and in both the fetal and mature airways, epithelial cells interact with mesenchymal cells to coordinate remodeling of tissue architecture in response to the mechanical environment. PMID:16460284

  16. Real-time assessment of surface interactions with titanium passivation layer by surface plasmon resonance

    PubMed Central

    Hirata, Isao; Yoshida, Yasuhiro; Nagaoka, Noriyuki; Hiasa, Kyou; Abe, Yasuhiko; Maekawa, Kenji; Kuboki, Takuo; Akagawa, Yasumasa; Suzuki, Kazuomi; Van Meerbeek, Bart; Messersmith, Phillip B.; Okazaki, Masayuki

    2011-01-01

    The high corrosion resistance and strength-to-density ratio makes titanium widely used in major industry, but also in a gamut of medical applications. Here we report for the first time on our development of a titanium passivation layer sensor that makes use of surface plasmon resonance (SPR). The deposited titanium metal layer on the sensor was passivated in air, like titanium medical devices. Our ‘Ti-SPR sensor’ enables analysis of biomolecules interactions with the passivated surface of titanium in real time. As a proof of concept, corrosion of titanium passivation layer exposed to acid was monitored in real time. Also, the Ti-SPR sensor can accurately measure the time-dependence of protein adsorption onto titanium passivation layer with a sub-nanogram per square millimeter accuracy. Besides such SPR analyses, an SPR-imaging (SPRI) enables real-time assessment of chemical surface processes that occur simultaneously at ‘multiple independent spots’ on the Ti-SPR sensor, such as acid-corrosion or adhesion of cells. Our Ti-SPR sensor will therefore be very useful to study titanium-corrosion phenomena and biomolecular titanium-surface interactions with application in a broad range of industrial and biomedical fields. PMID:22154862

  17. Crystalline Bacterial Surface Layer (S-Layer) Opens Golden Opportunities for Nanobiotechnology in Textiles.

    PubMed

    Asadi, Narges; Chand, Nima; Rassa, Mehdi

    2015-12-01

    This study focuses on the successful recrystallization of bacterial S-layer arrays of the Lactobacillus acidophilus ATCC 4356 at textile surfaces to create a novel method and material. Optimum bacterial growth was obtained at approximately 45 °C, pH 5.0, and 14 h pi. The cells were resuspended in guanidine hydrochloride and the 43 kDa S-protein was dialyzed and purified. The optimum reassembly on the polypropylene fabric surface in terms of scanning electron microscopy (SEM), reflectance, and uniformity (spectrophotometry) was obtained at 30 °C, pH 5.0 for 30 minutes in the presence of 2 gr/l (liquor ratio; 1:40) of the S-protein. Overall, our data showed that the functional aspects and specialty applications of the fabric would be very attractive for the textile and related sciences, and result in advanced technical textiles. PMID:26552090

  18. Numerical Computations of Hypersonic Boundary-Layer over Surface Irregularities

    NASA Technical Reports Server (NTRS)

    Chang, Chau-Lyan; Choudhari, Meelan M.; Li, Fei

    2010-01-01

    Surface irregularities such as protuberances inside a hypersonic boundary layer may lead to premature transition on the vehicle surface. Early transition in turn causes large localized surface heating that could damage the thermal protection system. Experimental measurements as well as numerical computations aimed at building a knowledge base for transition Reynolds numbers with respect to different protuberance sizes and locations have been actively pursued in recent years. This paper computationally investigates the unsteady wake development behind large isolated cylindrical roughness elements and the scaled wind-tunnel model of the trip used in a recent flight measurement during the reentry of space shuttle Discovery. An unstructured mesh, compressible flow solver based on the space-time conservation element, solution element (CESE) method is used to perform time-accurate Navier-Stokes calculations for the flow past a roughness element under several wind-tunnel conditions. For a cylindrical roughness element with a height to the boundary-layer thickness ratio from 0.8 to 2.5, the wake flow is characterized by a mushroom-shaped centerline streak and horse-shoe vortices. While time-accurate solutions converged to a steady-state for a ratio of 0.8, strong flow unsteadiness is present for a ratio of 1.3 and 2.5. Instability waves marked by distinct disturbance frequencies were found in the latter two cases. Both the centerline streak and the horse-shoe vortices become unstable downstream. The oscillatory vortices eventually reach an early breakdown stage for the largest roughness element. Spectral analyses in conjunction with the computed root mean square variations suggest that the source of the unsteadiness and instability waves in the wake region may be traced back to possible absolute instability in the front-side separation region.

  19. Exploring the bronzing effect at the surface of ink layers

    NASA Astrophysics Data System (ADS)

    Hébert, Mathieu; Mallet, Maxime; Deboos, Alexis; Chavel, Pierre; Kuang, Deng-Feng; Hugonin, Jean-Paul; Besbes, Mondher; Cazier, Anthony

    2015-03-01

    We investigate the optical phenomenon responsible for the colored shine that sometimes appears at the surface of ink layers in the specular direction, often called bronzing or gloss differential. It seems to come from the wavelength-dependent refractive index of the ink, which induces a wavelength-dependent reflectance of the ink-air interface. Our experiments on cyan and magenta inkjet inks confirm this theory. Complex refractive indices can be obtained from measurements of the spectral reflectance and transmittance of a transparency film coated with the ink. We propose a correction of the classical Clapper-Yule model in order to include the colored gloss in the prediction of the spectral reflectance of an inked paper. We also explored effects of scattering by the micrometric or nanometric roughness of the ink surface. The micrometric roughness, easy to model with a geometrical optics model, can predict the spreading of the colored gloss over a large cone. Electromagnetic models accounting for the effect of the nanometric roughness of the surface also predict the attenuation of short wavelengths observed under collimated illumination.

  20. Characterization of cathode keeper wear by surface layer activation

    NASA Technical Reports Server (NTRS)

    Polk, James E.

    2003-01-01

    In this study, the erosion rates of the discharge cathode keeper in a 30 cm NSTAR configuration ion thruster were measured using a technique known as Surface Layer Activation (SLA). This diagnostic technique involves producing a radioactive tracer in a given surface by bombardment with high energy ions. The decrease in activity of the tracer material may be monitored as the surface is subjected to wear processes and correlated to a depth calibration curve, yielding the eroded depth. Analysis of the activities was achieved through a gamma spectroscopy system. The primary objectives of this investigation were to reproduce erosion data observed in previous wear studies in order to validate the technique, and to determine the effect of different engine operating parameters on erosion rate. The erosion profile at the TH 15 (23 kw) setting observed during the 8200 hour Life Demonstration Test (LDT) was reproduced. The maximum keeper erosion rate at this setting was determined to be 0.085 pm/hr. Testing at the TH 8 (1.4 kw) setting demonstrated lower erosion rates than TH 15, along with a different wear profile. Varying the keeper voltage was shown to have a significant effect on the erosion, with a positive bias with respect to cathode potential decreasing the erosion rate significantly. Accurate measurements were achieved after operating times of only 40 to 70 hours, a significant improvement over other erosion diagnostic methods.

  1. Modelling boundary layer flow over barnacle-fouled surfaces

    NASA Astrophysics Data System (ADS)

    Sadique, Jasim; Yang, Xiang; Meneveau, Charles; Mittal, Rajat

    2014-11-01

    Macro-biofouling is a critical concern for the marine industry. However, there is little data on flow and drag over such surfaces. Accurate modelling of such multi-scale flows remains a big challenge. Such simulations are vital in providing insights into the fundamental flow physics, and they can be used to estimate the timing, need and effectiveness of measures used to counteract bio-fouling. This talk focuses on the use of a sharp-interface immersed boundary method coupled with a wall model and large-eddy simulations to carry out accurate simulations of a turbulent boundary layer flow over macro-fouled surfaces. For the current study, high resolution scans of barnacles were used to create simple geometrical representations. Simulations were then carried out to test how well these simpler geometric models mimic the flow over actual barnacles. Simulations of array of modeled barnacles, with different barnacle densities have also been carried out and we present results on the effect distribution density on the flow physics and drag on the surfaces. This work is funded by ONR Grant N00014-12-1-0582.

  2. Surface plasma source with anode layer plasma accelerator

    SciTech Connect

    Dudnikov, Vadim

    2012-02-15

    Proposed plasma generation system can be used for high current negative ion beam production and for directed deposition by flux of sputtered neutrals and negative ions. The main mechanism of negative ion formation in surface plasma sources is the secondary emission from low work function surface bombarded by a flux of positive ion or neutrals. The emission of negative ions is enhanced significantly by introducing a small amount of cesium or other substance with low ionization potential. In the proposed source are used positive ions generated by Hall drift plasma accelerator (anode layer plasma accelerator or plasma accelerator with insulated channel, with cylindrical or race track configuration of emission slit). The target-emitter is bombarded by the ion beam accelerated in crossed ExB fields. Negative ions are extracted from the target surface with geometrical focusing and are accelerated by negative voltage applied between emitter and plasma, contacting with the plasma accelerator. Hall drift ion source has a special design with a space for passing of the emitted negative ions and sputtered particles through the positive ion source.

  3. Can mobilization of the coarse surface layer release fine sediment trapped beneath the surface?

    NASA Astrophysics Data System (ADS)

    Wydzga, M. A.; Venditti, J. G.; Dunne, T.

    2006-12-01

    The U.S. EPA estimates that 40 percent of U.S. rivers are ecologically impaired by sedimentation. On dam- controlled rivers that are impaired by sedimentation, flushing flows with the potential to flush the fine sediments are commonly prescribed to improve ecological conditions. One goal of these flushing flows is to mobilize the riverbed's coarse surface layer and thus to create the potential to release fine sediment trapped beneath the surface. Given the economical value of water, releasing flows large enough to generate shear stresses adequate to mobilize the coarse surface can be difficult. Gravel augmentation using fine gravel has been recently demonstrated as a viable alternative to mobilizing coarse surface layers. This occurs because sheets of fine gravel smooth the bed, increasing the local shear stress available to move the grains. Does the mobilization of the coarse surface layer by fine gravel increase the depth to which fines are selectively removed or decrease the amount of fine sediment in the bed subsurface? To answer this question we conducted two series of laboratory experiments designed to flush or selectively remove fine sediment from the bed subsurface in a 28 m long and 0.86 m wide gravel-bedded flume channel. Before each experiment, we fed fine sediment (2,000 g/min; D50 = 0.4 mm) into the flume to saturate the gravel bed (D50 = 10 mm). The flow during the infiltration period was competent to transport the sand as bedload but not to suspend it (Q = 0.05 m3/s). In the first series of experiments, we attempted to flush the fine sediment from a non-mobile bed with a steady flow that was not competent to mobilize the coarse surface layer (Q = 0.205 m3/s). In the second set of experiments, the magnitude (Q = 0.205 m3/s) and duration of the flow conditions were the same; however, we fed fine gravel into the flume that moved thru the flume as bedload sheets and mobilized the coarse surface layer. After each experiment, we photographed the bed

  4. The theoretical model of atmospheric turbulence spectrum in surface layer

    NASA Astrophysics Data System (ADS)

    Liu, Shida; Liu, Shikuo; Xin, Guojun; Liang, Fuming

    1994-12-01

    It is shown that the slope of energy spectrum obtained from the velocity solution of Kdv—Burgers equation lies between —5/3 and—2 in the dilogarithmic coordinates paper. The spectrum is very close to one of Kolmogorov's isotropic turbulence and Frisch's intermittent turbulence in inertial region. In this paper, the Kdv-Burgers equation to describe atmospheric boundary layer turbulence is obtained. In the equation, the 1 / R e corresponds to dissipative coefficient v, R /2 t to dispersive coefficient β, then ( v/2 β)2 corresponds to 1 / R 2 e • Ri. We prove that the wave number corresponding to maximum energy spectrum S(k) decreases with the decrease of stability (i.e., the increase of ( v / 2 β)2 in eddy—containing region. And the spectrim amplitude decreases with the increase of ( v / 2 β)2 (i.e., the decrease of stability). These results are consistent with actual turbulence spectrum of atmospheric surface layer from turbulence data.

  5. GYROSCOPIC PUMPING IN THE SOLAR NEAR-SURFACE SHEAR LAYER

    SciTech Connect

    Miesch, Mark S.; Hindman, Bradley W.

    2011-12-10

    We use global and local helioseismic inversions to explore the prevailing dynamical balances in the solar near-surface shear layer (NSSL). The differential rotation and meridional circulation are intimately linked, with a common origin in the turbulent stresses of the upper solar convection zone. The existence and structure of the NSSL cannot be attributed solely to the conservation of angular momentum by solar surface convection, as is often supposed. Rather, the turbulent angular momentum transport accounts for the poleward meridional flow while the often overlooked meridional force balance is required to maintain the mid-latitude rotational shear. We suggest that the base of the NSSL is marked by a transition from baroclinic to turbulent stresses in the meridional plane which suppress Coriolis-induced circulations that would otherwise establish a cylindrical rotation profile. The turbulent angular momentum transport must be nondiffusive and directed radially inward. Inferred mean flows are consistent with the idea that turbulent convection tends to mix angular momentum but only if the mixing efficiency is inhomogeneous and/or anisotropic. The latitudinal and longitudinal components of the estimated turbulent transport are comparable in amplitude and about an order of magnitude larger than the vertical component. We estimate that it requires 2%-4% of the solar luminosity to maintain the solar NSSL against the inertia of the mean flow. Most of this energy is associated with the turbulent transport of angular momentum out of the layer, with a spin-down timescale of {approx}600 days. We also address implications of these results for numerical modeling of the NSSL.

  6. Gyroscopic Pumping in the Solar Near-surface Shear Layer

    NASA Astrophysics Data System (ADS)

    Miesch, Mark S.; Hindman, Bradley W.

    2011-12-01

    We use global and local helioseismic inversions to explore the prevailing dynamical balances in the solar near-surface shear layer (NSSL). The differential rotation and meridional circulation are intimately linked, with a common origin in the turbulent stresses of the upper solar convection zone. The existence and structure of the NSSL cannot be attributed solely to the conservation of angular momentum by solar surface convection, as is often supposed. Rather, the turbulent angular momentum transport accounts for the poleward meridional flow while the often overlooked meridional force balance is required to maintain the mid-latitude rotational shear. We suggest that the base of the NSSL is marked by a transition from baroclinic to turbulent stresses in the meridional plane which suppress Coriolis-induced circulations that would otherwise establish a cylindrical rotation profile. The turbulent angular momentum transport must be nondiffusive and directed radially inward. Inferred mean flows are consistent with the idea that turbulent convection tends to mix angular momentum but only if the mixing efficiency is inhomogeneous and/or anisotropic. The latitudinal and longitudinal components of the estimated turbulent transport are comparable in amplitude and about an order of magnitude larger than the vertical component. We estimate that it requires 2%-4% of the solar luminosity to maintain the solar NSSL against the inertia of the mean flow. Most of this energy is associated with the turbulent transport of angular momentum out of the layer, with a spin-down timescale of ~600 days. We also address implications of these results for numerical modeling of the NSSL.

  7. Selective visualisation of sensory receptors in the smooth muscle layer of ex-vivo airway whole-mounts by styryl pyridinium dyes.

    PubMed

    De Proost, Ian; Pintelon, Isabel; Brouns, Inge; Timmermans, Jean-Pierre; Adriaensen, Dirk

    2007-09-01

    Recently, we established the location, morphology and neurochemical coding of vagal smooth-muscle-associated airway receptors (SMARs) in rat lungs. These receptors were characterised as branching laminar terminals that originated from myelinated nerve fibres and were intercalated between airway smooth-muscle bundles. To allow the direct physiological examination of these receptors, the present investigation aimed at visualising SMARs in airway whole-mounts of rat and mouse lungs ex vivo. Short incubation with various styryl pyridinium dyes (AM1-43, FM2-10, FM4-64 or 4-Di-2-ASP) gave a highly selective fluorescent visualisation of both laminar nerve terminals and myelinated fibres from which they originated throughout the intrapulmonary airway tree in mouse and in rat. The reliable and specific labelling of SMARs ex vivo with these lipophilic membrane dyes was confirmed via immunostaining for protein gene-product 9.5 and vesicular glutamate transporters. Similar to the intrapulmonary location of NEBs, these SMARs appeared to be even more explicitly located near airway bifurcations. Both the trachealis muscle and the smooth-muscle bundles of extrapulmonary bronchi were also shown to contain laminar nerve terminals that were morphologically similar to the SMARs reported in the intrapulmonary airways. Thus, this study provides an in-vitro model enabling, for the first time, the fast and reliable visualisation of SMARs and the myelinated nerve fibres from which they originate in airway whole-mount preparations ex vivo. As such, this model opens up further perspectives and creates a valid basis for direct physiological measurement and manipulation of the individually identified airway receptors. PMID:17522895

  8. Water Surface Ripples Generated by the Turbulent Boundary Layer of a Surface-Piercing Moving Wall

    NASA Astrophysics Data System (ADS)

    Washuta, N.; Masnadi, N.; Duncan, J. H.

    2014-11-01

    Free surface ripples created by subsurface turbulence along a surface-piercing moving wall are studied experimentally. In this experiment, a meter-wide stainless steel belt travels horizontally in a loop around two rollers with vertically oriented axes, which are separated by 7.5 meters. One of the two 7.5-m-long belt sections between the rollers is in contact with the water in a large open-surface water tank and the water level is adjusted so that the top of the belt pierces the water free surface. The belt is launched from rest with a 3 g acceleration in order to quickly reach a steady state velocity. This belt motion creates a temporally evolving boundary layer analogous to the spatially evolving boundary layer created along the side of a ship hull moving at the belt velocity, with a length equivalent to the length of belt that has passed the measurement region. The water surface ripples generated by the subsurface turbulence are measured in a plane normal to the belt using a cinematic LIF technique. It is found that the overall RMS surface fluctuations increase linearly with belt speed and that the spatial distributions of the fluctuations show a sharp increase near the wall. The support of the Office of Naval Research is gratefully acknowledged.

  9. The North Atlantic surface layer and the shallow overturning circulation

    NASA Astrophysics Data System (ADS)

    Busecke, Julius; Gordon, Arnold L.

    2014-05-01

    gradient might be a mechanism for seasonally enhanced mesoscale turbulence, which could be important for the seasonal mixed layer budget as well as interannual variability in surface properties within the SSS-max.

  10. 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

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

    2015-10-16

    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, Ca(2+)- 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

  11. Novel routes for direct preparation of surface-modifying polyelectrolyte layers and patterned polymer surfaces

    NASA Astrophysics Data System (ADS)

    Sankhe, Amit Y.

    The focus of this research was on the use of surface-confined atom transfer radical polymerization (SC-ATRP) for growing surface-tethered brushes of electrolytic or charged monomers on solid substrates. The use of SC-ATRP to produce well-defined polymer brushes from monomers with non-ionic functionalities in aprotic solvents has been well documented. Although it is possible to produce PE brushes by postpolymerization chemical conversion of some neutral brushes, this approach limits the types of PE brushes that can be produced and uses organic solvents. Thus, to more widely open the design envelope in terms of types of PE brushes that can be made and to reduce the use of organic solvents, it would be beneficial to directly synthesize PE brushes using more environmentally friendly, "green" solvents, such as water, for the reaction media. But the direct ATRP of hydrophilic monomers with ionic groups presents new challenges due to the complex interactions of the charged monomers and water with the ATRP catalyst. In this dissertation, I report findings on SC-ATRP of charged monomers such as itaconic acid (IA), methacrylic acid (MAA) and sodium 4-styrenesulfonate (SS) in aqueous solutions. Surface-tethered polyelectrolyte brushes comprised of poly(itaconic acid) (PIA), poly(methacrylic acid) (PMAA) and poly(4-styrenesulfonate) (PSS) were grown using surface-confined atom transfer radical polymerization (ATRP). The surface-tethered initiator monolayer was formed by self-assembling 2-bromoisobutyryl bromide terminated thiol molecules on gold coated silicon substrates. This polymerization initiator molecule and a copper-based organometallic catalyst allowed tethered polyelectrolyte chains to be grown via radical polymerization at room temperature in aqueous solutions. To suppress consumption of the ATRP deactivator, a halide salt was added to the reaction mixture, which enabled controlled growth of the polyelectrolyte layers. Phase-modulated ellipsometry was used to follow

  12. Thin hydroxyapatite surface layers on titanium produced by ion implantation

    NASA Astrophysics Data System (ADS)

    Baumann, H.; Bethge, K.; Bilger, G.; Jones, D.; Symietz, I.

    2002-11-01

    In medicine metallic implants are widely used as hip replacement protheses or artificial teeth. The biocompatibility is in all cases the most important requirement. Hydroxyapatite (HAp) is frequently used as coating on metallic implants because of its high acceptance by the human body. In this paper a process is described by which a HAp surface layer is produced by ion implantation with a continuous transition to the bulk material. Calcium and phosphorus ions are successively implanted into titanium under different vacuum conditions by backfilling oxygen into the implantation chamber. Afterwards the implanted samples are thermally treated. The elemental composition inside the implanted region was determined by nuclear analysis methods as (α,α) backscattering and the resonant nuclear reaction 1H( 15N,αγ) 12C. The results of X-ray photoelectron spectroscopy indicate the formation of HAp. In addition a first biocompatibility test was performed to compare the growing of marrow bone cells on the implanted sample surface with that of titanium.

  13. Turbulent boundary layer over a convergent and divergent superhydrophobic surface

    NASA Astrophysics Data System (ADS)

    Nadeem, Muhammad; Hwang, Jinyul; Sung, Hyung Jin

    2015-11-01

    Direct numerical simulation (DNS) of spatially developing turbulent boundary layer (TBL) over a convergent and divergent superhydrophobic surface (SHS) was performed. The convergent and divergent SHS was aligned in the streamwise direction. The SHS was modeled as a pattern of slip and no-slip surfaces. For comparison, DNS of TBL over a straight SHS was also carried out. The momentum thickness Reynolds number was varied from 800 to 1400. The gas fraction of the convergent and divergent SHS was the same as that of the straight SHS, keeping the slip area constant. The slip velocity in the convergent SHS was higher than that of the straight SHS. An optimal streamwise length of the convergent and divergent SHS was obtained. The convergent and divergent SHS gave more drag reduction than the straight SHS. The convergent and divergent SHS led to the modification of near wall-turbulent structures, resembling the narrowing and widening streaky structures near the wall. The convergent and divergent SHS had a relatively larger damping effect on near-wall turbulence than the straight SHS. These observations will be further analyzed statistically to demonstrate the effect of the convergent and divergent SHS on the interaction of inner and outer regions of TBL.

  14. Characterization of Floating Surface Layers of Lipids and Lipopolymers by Surface-Sensitive Scattering

    NASA Astrophysics Data System (ADS)

    Krüger, Peter; Lösche, Mathias

    Nanotechnology and molecular (bio-)engineering are making ever deepening inroads into everybodys daily life. Physicochemical and biotechnological achievements in the design of physiologically active supramolecular assemblies have brought about the quest for their submolecular-level characterization. We employ surface-sensitive scattering techniques for the investigation of planar lipid membranes - floating monolayers on aqueous surfaces - to correlate structural, functional and dynamic aspects of biomembrane models. This chapter surveys recent work on the submolecular structure of floating phospholipid monolayers - where the advent of third-generation synchrotron X-ray sources has driven the development of realistic, submolecular-scale quasi-chemical models - as well as of more complex systems: cation binding to anionic lipid surfaces; conformational changes of lipopolymers undergoing phase transitions; the conformational organization of phosphatidylinositol and phosphatidylinositides, as examples of physiologically important lipids; and the adsorption of peptides (neuropeptide Y, NPY) or solvents (dimethylsulfoxide, DMSO) onto phospholipid surface layers.

  15. Extending the Diffuse Layer Model of Surface Acidity Constant Behavior: IV. Diffuse Layer Charge/Potential Relationships

    EPA Science Inventory

    Most current electrostatic surface complexation models describing ionic binding at the particle/water interface rely on the use of Poisson - Boltzmann (PB) theory for relating diffuse layer charge densities to diffuse layer electrostatic potentials. PB theory is known to contain ...

  16. New Material Development for Surface Layer and Surface Technology in Tribology Science to Improve Energy Efficiency

    NASA Astrophysics Data System (ADS)

    Ismail, R.; Tauviqirrahman, M.; Jamari, Jamari; Schipper, D. J.

    2009-09-01

    This paper reviews the development of new material and surface technology in tribology and its contribution to energy efficiency. Two examples of the economic benefits, resulted from the optimum tribology in the transportation sector and the manufacturing industry are discussed. The new materials are proposed to modify the surface property by laminating the bulk material with thin layer/coating. Under a suitable condition, the thin layer on a surface can provide a combination of good wear, a low friction and corrosion resistance for the mechanical components. The innovation in layer technology results molybdenum disulfide (MoS2), diamond like carbon (DLC), cubic boron nitride (CBN) and diamond which perform satisfactory outcome. The application of the metallic coatings to carbon fibre reinforced polymer matrix composites (CFRP) has the capacity to provide considerable weight and power savings for many engineering components. The green material for lubricant and additives such as the use of sunflower oil which possesses good oxidation resistance and the use of mallee leaves as bio-degradable solvent are used to answer the demand of the environmentally friendly material with good performance. The tribology research implementation for energy efficiency also touches the simple things around us such as: erasing the laser-print in a paper with different abrasion techniques. For the technology in the engineering surface, the consideration for generating the suitable surface of the components in running-in period has been discussed in order to prolong the components life and reduce the machine downtime. The conclusion, tribology can result in reducing manufacturing time, reducing the maintenance requirements, prolonging the service interval, improving durability, reliability and mechanical components life, and reducing harmful exhaust emission and waste. All of these advantages will increase the energy efficiency and the economic benefits.

  17. Emergency airway puncture

    MedlinePlus

    Emergency airway puncture is the placement of a hollow needle through the throat into the airway. It ... Emergency airway puncture is done in an emergency situation, when someone is choking and all other efforts ...

  18. Surface-layer protein from Caulobacter crescentus: expression, purification and X-ray crystallographic analysis.

    PubMed

    Jones, Michael D; Chan, Anson C K; Nomellini, John F; Murphy, Michael E P; Smit, John

    2016-09-01

    Protein surface layers are self-assembling, paracrystalline lattices on the surface of many prokaryotes. Surface-layer proteins have not benefited from widespread structural analysis owing to their resistance to crystallization. Here, the successful expression of a truncated version of RsaA, the surface-layer protein from Caulobacter crescentus, from a Caulobacter protein-expression system is reported. The purification, crystallization and initial X-ray diffraction analysis of the truncated RsaA, the largest surface-layer protein studied to date and the first from a Gram-negative bacterium, are also reported. PMID:27599857

  19. Enrichment and association of lead and bacteria at particulate surfaces in a salt-marsh surface layer

    USGS Publications Warehouse

    Harvey, R.W.; Lion, Leonard W.; Young, L.Y.; Leckie, J.O.

    1982-01-01

    The particle-laden surface layer (approx 150-370 mu m) and subsurface waters of a South San Francisco Bay salt marsh were sampled over 2 tidal cycles and analyzed for particle numbers and particulate-associated and total concentrations of Pb and bacteria. Laboratory studies examined the ability of a bacterial isolate from the surface layer and a bacterial 'film-former' to sorb Pb at environmentally significant concentrations in seawater. Degrees by which Pb concentrated in the surface layer relative to the subsurface strongly correlated with enrichments of surface layer bacteria (bacterioneuston). A significant fraction of the bacterioneuston and surface layer Pb were associated with particles. Particle-bound bacterioneuston may interact with Pb at particulate surfaces in this microenvironment.

  20. 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

  1. The surface and through crack problems in layered orthotropic plates

    NASA Technical Reports Server (NTRS)

    Erdogan, Fazil; Wu, Binghua

    1991-01-01

    An analytical method is developed for a relatively accurate calculation of Stress Intensity Factors in a laminated orthotropic plate containing a through or part-through crack. The laminated plate is assumed to be under bending or membrane loading and the mode 1 problem is considered. First three transverse shear deformation plate theories (Mindlin's displacement based first-order theory, Reissner's stress-based first-order theory, and a simple-higher order theory due to Reddy) are reviewed and examined for homogeneous, laminated and heterogeneous orthotropic plates. Based on a general linear laminated plate theory, a method by which the stress intensity factors can be obtained in orthotropic laminated and heterogeneous plates with a through crack is developed. Examples are given for both symmetrically and unsymmetrically laminated plates and the effects of various material properties on the stress intensity factors are studied. In order to implement the line-spring model which is used later to study the surface crack problem, the corresponding plane elasticity problem of a two-bonded orthotropic plated containing a crack perpendicular to the interface is also considered. Three different crack profiles: an internal crack, an edge crack, and a crack terminating at the interface are considered. The effect of the different material combinations, geometries, and material orthotropy on the stress intensity factors and on the power of stress singularity for a crack terminating at the interface is fully examined. The Line Spring model of Rice and Levy is used for the part-through crack problem. The surface crack is assumed to lie in one of the two-layered laminated orthotropic plates due to the limitation of the available plane strain results. All problems considered are of the mixed boundary value type and are reduced to Cauchy type of singular integral equations which are then solved numerically.

  2. Dual Nature of Heat Flux in Stable Atmospheric Surface Layer

    NASA Astrophysics Data System (ADS)

    Srivastava, P.; Sharan, M.

    2015-12-01

    The behavior of heat flux (H) with respect to the stability parameter (ζ) in stable surface layer (SSL) is analyzed with in the framework of Monin-Obukhov similarity (MOS) theory. The analytical expressions of H are obtained as functions of wind speed (U) and wind shear (dU/dz) using the linear similarity functions and accordingly two cases, (i) U = δ (constant) and (ii) dU/dz = δ are considered. The mathematical analysis shows that the magnitude of H increases with ζ till it attains a maximum value at ζ =ζc and then starts decreasing with increasing stability suggesting the dual characteristic of heat flux with stability parameter. The point of maximum heat flux is found to be dependent on the roughness length (z0) as well as the height above the surface. An attempt has been made to analyze the sensitivity of this dual characteristic of H with ζ using the non-linear similarity functions. The analysis shows that the dual nature of H persists in the case of linear as well as non-linear similarity functions. However, the point of extremum appears to be dependent on the nature of the similarity functions. Turbulent data over a tropical site Ranchi (India) is analyzed to validate the observed nature of H with the theoretical nature as predicted by MOS. The analysis of observational data reveals the non-existence of any preferred stability state in SSL as speculated by Wang and Bras (2010, 2011) and supports the conclusions of Malhi 1995, Derbyshire 1999, van de Wiel et al. 2007, Basu et al. 2008, and van de Wiel et al. 2011. Thus, the non-uniqueness of MOS equations does not appear to be a mathematical artifact and it is consistent with the observations as far as the nature of heat flux with respect to stability parameter in SSL is concerned.

  3. Airway Gland Structure and Function.

    PubMed

    Widdicombe, Jonathan H; Wine, Jeffrey J

    2015-10-01

    Submucosal glands contribute to airway surface liquid (ASL), a film that protects all airway surfaces. Glandular mucus comprises electrolytes, water, the gel-forming mucin MUC5B, and hundreds of different proteins with diverse protective functions. Gland volume per unit area of mucosal surface correlates positively with impaction rate of inhaled particles. In human main bronchi, the volume of the glands is ∼ 50 times that of surface goblet cells, but the glands diminish in size and frequency distally. ASL and its trapped particles are removed from the airways by mucociliary transport. Airway glands have a tubuloacinar structure, with a single terminal duct, a nonciliated collecting duct, then branching secretory tubules lined with mucous cells and ending in serous acini. They allow for a massive increase in numbers of mucus-producing cells without replacing surface ciliated cells. Active secretion of Cl(-) and HCO3 (-) by serous cells produces most of the fluid of gland secretions. Glands are densely innervated by tonically active, mutually excitatory airway intrinsic neurons. Most gland mucus is secreted constitutively in vivo, with large, transient increases produced by emergency reflex drive from the vagus. Elevations of [cAMP]i and [Ca(2+)]i coordinate electrolyte and macromolecular secretion and probably occur together for baseline activity in vivo, with cholinergic elevation of [Ca(2+)]i being mainly responsive for transient increases in secretion. Altered submucosal gland function contributes to the pathology of all obstructive diseases, but is an early stage of pathogenesis only in cystic fibrosis. PMID:26336032

  4. Layer by layer removal of Au atoms from passivated Au(111) surfaces using the scanning tunneling microscope: Nanoscale ``paint stripping''

    NASA Astrophysics Data System (ADS)

    Keel, J. M.; Yin, J.; Guo, Q.; Palmer, R. E.

    2002-04-01

    Layer by layer removal of gold atoms from the (111) surface of gold has been performed using the scanning tunneling microscope. The process is made possible by a chemisorbed self-assembled monolayer (SAM) of dodecanethiol molecules on the surface, which gives rise to a reduced bonding strength between the top two layers of gold atoms. The gold atoms and associated adsorbed molecules are peeled off and displaced laterally by the STM tip, and the size of the modified area (down to ˜10×10 nm) is more or less determined by the scan size.

  5. Surface Passivation by Quantum Exclusion Using Multiple Layers

    NASA Technical Reports Server (NTRS)

    Hoenk, Michael E. (Inventor)

    2013-01-01

    A semiconductor device has a multilayer doping to provide improved passivation by quantum exclusion. The multilayer doping includes a plurality M of doped layers, where M is an integer greater than 1. The dopant sheet densities in the M doped layers need not be the same, but in principle can be selected to be the same sheet densities or to be different sheet densities. M-1 interleaved layers provided between the M doped layers are not deliberately doped (also referred to as "undoped layers"). Structures with M=2, M=3 and M=4 have been demonstrated and exhibit improved passivation.

  6. Patterning of gold nanoparticles on fluoropolymer films by using patterned surface grafting and layer-by-layer deposition techniques.

    PubMed

    Jung, Chang-Hee; Hwang, In-Tae; Jung, Chan-Hee; Choi, Jae-Hak; Kwon, Oh-Sun; Shin, Kwanwoo

    2013-09-11

    The patterning of gold nanoparticles (GNPs) on the surface of a fluoropolymer substrate by using patterned surface grafting and layer-by-layer deposition techniques is described. The surface of a poly(tetrafluoroethylene-co-perfluorovinyl ether) (PFA) substrate was selectively implanted with 150 keV proton ions. Peroxide groups were successfully formed on the implanted PFA surface, and their concentration depended on the fluence. Acrylic acid was graft polymerized onto the implanted regions of the PFA substrate, resulting in well-defined patterns of poly(acrylic acid) (PAA) on the PFA substrate. The surface properties of the PAA-patterned PFA surface, such as chemical compositions, wettability, and morphology, were investigated. The surface analysis results revealed that PAA was definitely present on the implanted regions of the PFA surface, and the degree of grafting was dependent on three factors: fluence, grafting time, and monomer concentration. Furthermore, GNP patterns were generated on the prepared PAA-patterned PFA surface by layer-by-layer deposition of GNPs and poly(diallyldimethyl ammonium chloride). The multilayers of GNPs were deposited only onto the PAA-grafted regions separated by bare PFA regions, and the resulting GNP patterns exhibited good electrical conductivity. PMID:23927646

  7. Surface pressure fluctuations in hypersonic turbulent boundary layers

    NASA Technical Reports Server (NTRS)

    Raman, K. R.

    1974-01-01

    The surface pressure fluctuations on a flat plate model at hypersonic Mach numbers of 5.2, 7.4 and 10.4 with an attached turbulent boundary layer were measured using flush mounted small piezoelectric sensors. A high frequency resolution of the pressure field was achieved using specially designed small piezoelectric sensors that had a good frequency response well above 300 KHz. The RMS pressures and non-dimensional energy spectra for all above Mach numbers are presented. The convective velocities, obtained from space time correlation considerations are equal to 0.7 U sub infinity. The results indicate the RMS pressures vary from 5 to 25 percent of the mean static pressures. The ratios of RMS pressure to dynamic pressure are less than the universally accepted subsonic value of 6 x 10/3. The ratio decreases in value as the Mach number or the dynamic pressure is increased. The ratio of RMS pressure to wall shear for Mach number 7.4 satisfies one smaller than or equal to p/tau sub w smaller than or equal to three.

  8. Planetary boundary layer response to surface temperature anomalies forcing

    NASA Astrophysics Data System (ADS)

    Perrot, Xavier; Lapeyre, Guillaume; Plougonven, Riwal

    2015-04-01

    Recent studies showed that strong sea surface temperature (SST) fronts, on the scale of the western boundary currents, strongly affect the planetary boundary layer (PBL) but also all the troposphere. This renewed the interest of air-sea interactions at oceanic meso-scales. Mainly two mechanisms are proposed in the literature, the first one (due to Wallace et al 1989) is based on the destabilization of the PBL above SST anomalies, the second one (Lindzen and Nigam 1987) is based on the pressure anomalies linked to the atmosphere temperature adjustment to the SST. These two mechanisms predict different responses of the PBL to the SST. We did numerical simulations with a meso-scale atmospheric model (WRF) with the same configuration as the one described in Lambert et al 2013. The model is forced by a SST anomaly which is first a zonally or meridionally constant field and secondly a field of meso-scale structures. Firstly we studied the influence of the initial wind strength on the PBL response for the two different types of SST anomalies. We showed that the dominant mechanism can change according to weak or strong wind and to the orientation of the SST anomaly. Secondly after considering a dry atmosphere we switched on the humidity in our configuration. We studied how it influences the PBL response and whether the mechanism driving the PBL response is still the same as in the dry case.

  9. Continuity of airway goblet cells and intraluminal mucus in the airways of patients with bronchial asthma.

    PubMed

    Shimura, S; Andoh, Y; Haraguchi, M; Shirato, K

    1996-07-01

    The aim of this study was to elucidate the mechanism of the formation of the widespread mucous-plugging observed in autopsied lungs from patients with bronchial asthma. We performed morphometric analysis of airways of autopsied lungs from eight patients with bronchial asthma (Group BA), and compared it with those of six chronic bronchitics (Group CB) and four control patients (Control). The following parameters were measured in paraffin sections: volume proportion of bronchial glands to bronchial wall (Gland%); goblet cell granules to total epithelial layer (Goblet %); intraluminal mucus expressed as the mucus occupying ratio (MOR); volume ratio of intraluminal mucus continuous with goblet cells to total intraluminal mucus (Vc/Vtol %); and surface ratio of the contact surface of intraluminal mucus continuous with goblet cells to the total luminal surface (Sc/Stot %). Gland%, Goblet %, and MOR or inflammatory cell numbers in the airway walls both from Group BA and CB were larger than those from the Control group. However, no significant differences were observed between Group BA and CB in Gland%, Goblet %, MOR or inflammatory cell numbers, except for the eosinophil number: i.e. 23 +/- 3, 22 +/- 3 and 6 +/- 2% in Gland%; 22 +/- 9, 5 +/- 4 and 2 +/- 2% in Goblet%; 10 +/- 3, 18 +/- 3 and 0.3 +/- 0.5% in MOR; 199 +/- 68, 10 +/- 3 and 2 +/- 2 cells. mm-2 in eosinophil number of the peripheral airways from Groups BA, CB and Control, respectively. In contrast, marked and significant increases were observed both in Vc/Vtot% and Sc/Stot% in Group BA compared to Groups CB and Control both in central and peripheral airways: i.e. Vc/Vtot% in the peripheral airways was 53 +/- 5, 4 +/- 3 and 0.8 +/- 0.8% from Groups BA, CB and Control, respectively (BA vs CB or BA vs Control, p < 0.01 each). These findings suggest that the continuity of goblet cells and intraluminal mucus or lack of full release of mucus, from goblet cells, is peculiar to asthmatic airways, and may contribute to

  10. Physiological Impact of Abnormal Lipoxin A4 Production on Cystic Fibrosis Airway Epithelium and Therapeutic Potential

    PubMed Central

    Higgins, Gerard; McNally, Paul; Urbach, Valérie

    2015-01-01

    Lipoxin A4 has been described as a major signal for the resolution of inflammation and is abnormally produced in the lungs of patients with cystic fibrosis (CF). In CF, the loss of chloride transport caused by the mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) Cl− channel gene results in dehydration, mucus plugging, and reduction of the airway surface liquid layer (ASL) height which favour chronic lung infection and neutrophil based inflammation leading to progressive lung destruction and early death of people with CF. This review highlights the unique ability of LXA4 to restore airway surface hydration, to stimulate airway epithelial repair, and to antagonise the proinflammatory program of the CF airway, circumventing some of the most difficult aspects of CF pathophysiology. The report points out novel aspects of the cellular mechanism involved in the physiological response to LXA4, including release of ATP from airway epithelial cell via pannexin channel and subsequent activation of and P2Y11 purinoreceptor. Therefore, inadequate endogenous LXA4 biosynthesis reported in CF exacerbates the ion transport abnormality and defective mucociliary clearance, in addition to impairing the resolution of inflammation, thus amplifying the vicious circle of airway dehydration, chronic infection, and inflammation. PMID:25866809

  11. 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 ...

  12. Modification of surface oxide layers of titanium targets for increasing lifetime of neutron tubes

    SciTech Connect

    Zakharov, A. M. Dvoichenkova, O. A.; Evsin, A. E.

    2015-12-15

    The peculiarities of interaction of hydrogen ions with a titanium target and its surface oxide layer were studied. Two ways of modification of the surface oxide layers of titanium targets for increasing the lifetime of neutron tubes were proposed: (1) deposition of an yttrium oxide barrier layer on the target surface; (2) implementation of neutron tube work regime in which the target is irradiated with ions with energies lower than 1000 eV between high-energy ion irradiation pulses.

  13. Modification of surface oxide layers of titanium targets for increasing lifetime of neutron tubes

    NASA Astrophysics Data System (ADS)

    Zakharov, A. M.; Dvoichenkova, O. A.; Evsin, A. E.

    2015-12-01

    The peculiarities of interaction of hydrogen ions with a titanium target and its surface oxide layer were studied. Two ways of modification of the surface oxide layers of titanium targets for increasing the lifetime of neutron tubes were proposed: (1) deposition of an yttrium oxide barrier layer on the target surface; (2) implementation of neutron tube work regime in which the target is irradiated with ions with energies lower than 1000 eV between high-energy ion irradiation pulses.

  14. Accurate Sound Velocity Measurement in Ocean Near-Surface Layer

    NASA Astrophysics Data System (ADS)

    Lizarralde, D.; Xu, B. L.

    2015-12-01

    Accurate sound velocity measurement is essential in oceanography because sound is the only wave that can propagate in sea water. Due to its measuring difficulties, sound velocity is often not measured directly but instead calculated from water temperature, salinity, and depth, which are much easier to obtain. This research develops a new method to directly measure the sound velocity in the ocean's near-surface layer using multi-channel seismic (MCS) hydrophones. This system consists of a device to make a sound pulse and a long cable with hundreds of hydrophones to record the sound. The distance between the source and each receiver is the offset. The time it takes the pulse to arrive to each receiver is the travel time.The errors of measuring offset and travel time will affect the accuracy of sound velocity if we calculated with just one offset and one travel time. However, by analyzing the direct arrival signal from hundreds of receivers, the velocity can be determined as the slope of a straight line in the travel time-offset graph. The errors in distance and time measurement result in only an up or down shift of the line and do not affect the slope. This research uses MCS data of survey MGL1408 obtained from the Marine Geoscience Data System and processed with Seismic Unix. The sound velocity can be directly measured to an accuracy of less than 1m/s. The included graph shows the directly measured velocity verses the calculated velocity along 100km across the Mid-Atlantic continental margin. The directly measured velocity shows a good coherence to the velocity computed from temperature and salinity. In addition, the fine variations in the sound velocity can be observed, which is hardly seen from the calculated velocity. Using this methodology, both large area acquisition and fine resolution can be achieved. This directly measured sound velocity will be a new and powerful tool in oceanography.

  15. Mathematical model of nucleotide regulation on airway epithelia. Implications for airway homeostasis.

    PubMed

    Zuo, Peiying; Picher, Maryse; Okada, Seiko F; Lazarowski, Eduardo R; Button, Brian; Boucher, Richard C; Elston, Timothy C

    2008-09-26

    In the airways, adenine nucleotides support a complex signaling network mediating host defenses. Released by the epithelium into the airway surface liquid (ASL) layer, they regulate mucus clearance through P2 (ATP) receptors, and following surface metabolism through P1 (adenosine; Ado) receptors. The complexity of ASL nucleotide regulation provides an ideal subject for biochemical network modeling. A mathematical model was developed to integrate nucleotide release, the ectoenzymes supporting the dephosphorylation of ATP into Ado, Ado deamination into inosine (Ino), and nucleoside uptake. The model also includes ecto-adenylate kinase activity and feed-forward inhibition of Ado production by ATP and ADP. The parameters were optimized by fitting the model to experimental data for the steady-state and transient concentration profiles generated by adding ATP to polarized primary cultures of human bronchial epithelial (HBE) cells. The model captures major aspects of ATP and Ado regulation, including their >4-fold increase in concentration induced by mechanical stress mimicking normal breathing. The model also confirmed the independence of steady-state nucleotide concentrations on the ASL volume, an important regulator of airway clearance. An interactive approach between simulations and assays revealed that feed-forward inhibition is mediated by selective inhibition of ecto-5'-nucleotidase. Importantly, the model identifies ecto-adenylate kinase as a key regulator of ASL ATP and proposes novel strategies for the treatment of airway diseases characterized by impaired nucleotide-mediated clearance. These new insights into the biochemical processes supporting ASL nucleotide regulation illustrate the potential of this mathematical model for fundamental and clinical research. PMID:18662982

  16. REGIONAL DIFFERENCES IN BIOELECTRIC PROPERTIES AND ION FLOW IN EXCISED CANINE AIRWAYS

    EPA Science Inventory

    Absorption of airway liquid, as it moves from the large surface area of distal airways to more central airway surfaces, is considered to be essential for regulation of the depth of airway liquid. The short-circuited excised canine trachea, however, secretes C(-1) and absorbs a le...

  17. Control of the morphology of lipid layers by substrate surface chemistry.

    PubMed

    Granqvist, Niko; Yliperttula, Marjo; Välimäki, Salla; Pulkkinen, Petri; Tenhu, Heikki; Viitala, Tapani

    2014-03-18

    In this study, surface coatings were used to control the morphology of the deposited lipid layers during vesicle spreading, i.e., to control if liposomes self-assemble on a surface into a supported lipid bilayer or a supported vesicular layer. The influence of the properties of the surface coating on formation of the deposited lipid layer was studied with quartz crystal microbalance and two-wavelength multiparametric surface plasmon resonance techniques. Control of lipid self-assembly on the surface was achieved by two different types of soft substrate materials, i.e., dextran and thiolated polyethylene glycol, functionalized with hydrophobic linkers for capturing the lipid layer. The low-molecular-weight dextran-based surface promoted formation of supported lipid bilayers, while the thiolated polyethylene glycol-based surface promoted supported vesicular layer formation. A silicon dioxide surface was used as a reference surface in both measurement techniques. In addition to promoting supported lipid bilayer formation of known lipid mixtures, the dextran surface also promoted supported lipid bilayer formation of vesicles containing the cell membrane extract of human hepatoblastoma cells. The new dextran-based surface was also capable of protecting the supported lipid bilayer against dehydration when exposed to a constant flow of air. The well-established quartz crystal microbalance technique was effective in determining the morphology of the formed lipid layer, while the two-wavelength surface plasmon resonance analysis enabled further complementary characterization of the adsorbed supported lipid bilayers and supported vesicular layers. PMID:24564782

  18. Airway injury during high-level exercise.

    PubMed

    Kippelen, Pascale; Anderson, Sandra D

    2012-05-01

    Airway epithelial cells act as a physical barrier against environmental toxins and injury, and modulate inflammation and the immune response. As such, maintenance of their integrity is critical. Evidence is accumulating to suggest that exercise can cause injury to the airway epithelium. This seems the case particularly for competitive athletes performing high-level exercise, or when exercise takes place in extreme environmental conditions such as in cold dry air or in polluted air. Dehydration of the small airways and increased forces exerted on to the airway surface during severe hyperpnoea are thought to be key factors in determining the occurrence of injury of the airway epithelium. The injury-repair process of the airway epithelium may contribute to the development of the bronchial hyper-responsiveness that is documented in many elite athletes. PMID:22247295

  19. Surfactant and allergic airway inflammation.

    PubMed

    Winkler, Carla; Hohlfeld, Jens M

    2013-01-01

    Pulmonary surfactant is a complex mixture of unique proteins and lipids that covers the airway lumen. Surfactant prevents alveolar collapse and maintains airway patency by reducing surface tension at the air-liquid interface. Furthermore, it provides a defence against antigen uptake by binding foreign particles and enhancing cellular immune responses. Allergic asthma is associated with chronic airway inflammation and presents with episodes of airway narrowing. The pulmonary inflammation and bronchoconstriction can be triggered by exposure to allergens or pathogens present in the inhaled air. Pulmonary surfactant has the potential to interact with various immune cells which orchestrate allergen- or pathogen-driven episodes of airway inflammation. The complex nature of surfactant allows multiple sites of interaction, but also makes it susceptible to external alterations, which potentially impair its function. This duality of modulating airway physiology and immunology during inflammatory conditions, while at the same time being prone to alterations accompanied by restricted function, has stimulated numerous studies in recent decades, which are reviewed in this article. PMID:23896983

  20. Surface-confined single-layer covalent organic framework on single-layer graphene grown on copper foil.

    PubMed

    Xu, Lirong; Zhou, Xin; Tian, Wei Quan; Gao, Teng; Zhang, Yan Feng; Lei, Shengbin; Liu, Zhong Fan

    2014-09-01

    The integration of 2D covalent organic frameworks (COFs) with atomic thickness with graphene will lead to intriguing two-dimensional materials. A surface-confined covalently bonded Schiff base network was prepared on single-layer graphene grown on copper foil and the dynamic reaction process was investigated with scanning tunneling microscopy. DFT simulations provide an understanding of the electronic structures and the interactions between the surface COF and graphene. Strong coupling between the surface COF and graphene was confirmed by the dispersive bands of the surface COF after interaction with graphene, and also by the experimental observation of tunneling condition dependent contrast of the surface COF. PMID:25145927

  1. Dynamics of heat, water, and soluble gas exchange in the human airways: 1. A model study.

    PubMed

    Tsu, M E; Babb, A L; Ralph, D D; Hlastala, M P

    1988-01-01

    In order to provide a means for analysis of heat, water, and soluble gas exchange with the airways during tidal ventilation, a one dimensional theoretical model describing heat and water exchange in the respiratory airways has been extended to include soluble gas exchange with the airway mucosa and water exchange with the mucous layer lining the airways. Not only do heat, water, and gas exchange occur simultaneously, but they also interact. Heating and cooling of the airway surface and mucous lining affects both evaporative water and soluble gas exchange. Water evaporation provides a major source of heat exchange. The model-predicted mean airway temperature profiles agree well with literature data for both oral and nasal breathing validating that part of the model. With model parameters giving the best fit to experimental data, the model shows: (a) substantial heat recovery in the upper airways, (b) minimal respiratory heat and water loss, and (c) low average mucous temperatures and maximal increases in mucous thickness. For resting breathing of room air, heat and water conservation appear to be more important than conditioning efficiency. End-tidal expired partial pressures of very soluble gases eliminated by the lungs are predicted to be lower than the alveolar partial pressures due to the absorption of the expired gases by the airway mucosa. The model may be usable for design of experiments to examine mechanisms associated with the local hydration and dehydration dynamics of the mucosal surface, control of bronchial perfusion, triggering of asthma, mucociliary clearance and deposition of inhaled pollutant gases. PMID:3228218

  2. Characterization of silane layers on modified stainless steel surfaces and related stainless steel-plastic hybrids

    NASA Astrophysics Data System (ADS)

    Honkanen, Mari; Hoikkanen, Maija; Vippola, Minnamari; Vuorinen, Jyrki; Lepistö, Toivo; Jussila, Petri; Ali-Löytty, Harri; Lampimäki, Markus; Valden, Mika

    2011-09-01

    The aim of this work was to characterize silane layers on the modified stainless steel surfaces and relate it to the adhesion in the injection-molded thermoplastic urethane-stainless steel hybrids. The silane layers were characterized with scanning electron microscope and transmission electron microscope, allowing the direct quantization of silane layer thickness and its variation. The surface topographies were characterized with atomic force microscope and chemical analyses were performed with X-ray photoelectron spectroscopy. The mechanical strength of the respective stainless steel-thermoplastic urethane hybrids was determined by peel test. Polishing and oxidation treatment of the steel surface improved the silane layer uniformity compared to the industrially pickled surface and increased the adhesion strength of the hybrids, resulting mainly cohesive failure in TPU. XPS analysis indicated that the improved silane bonding to the modified steel surface was due to clean Fe 2O 3-type surface oxide and stronger interaction with TPU was due to more amino species on the silane layer surface compared to the cleaned, industrially pickled surface. Silane layer thickness affected failure type of the hybrids, with a thick silane layer the hybrids failed mainly in the silane layer and with a thinner layer cohesively in plastic.

  3. Flux measurements in the near surface layer over a non-uniform crop surface in China

    NASA Astrophysics Data System (ADS)

    Gao, Z.; Bian, L.; Liu, S.

    2005-06-01

    Eddy covariance measurements were conducted on fluxes of moisture, heat and CO2 in a near-surface layer over a non-uniform crop surface in an agricultural ecosystem in the central plain of China from 10 June to 20 July 2002. During this period, the mean canopy height was about 0.50 m. The study site consisted of grass (10% of area), bean (15%), corn (15%) and rice (60%). Based on footprint analysis, we expected >90% of the measured flux (at a height of 4 m above ground surface) to occur within the nearest 600 m of upwind area. We examined interdiurnal variations in the components of the surface energy balance and in CO2 flux. Results show that the pattern of energy partition had no obvious variation during the season. Daytime absorption of CO2 flux by the crop canopy suddenly increased after thunderstorm events. We examined the energy budget closure and found it to be around 0.85. We compared energy partitioning for all rain-free days, and found energy imbalance was more significant for the 1~3 days after rainy events and energy components almost achieve balance for the other rain-free days. It indicated that the cold or warm rainwater infiltrating into soil made problems.

  4. Surface coating for flame retardant behavior of cotton fabric by layer-by-layer processing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Flame retardant behavior has been prepared by the layer-by layer assemblies of branched polyethylenimine (BPEI), kaolin, urea, diammonium phosphate (dibasic) on cotton fabrics. Three different kinds of cotton fabrics (print cloth, mercerized print cloth, and mercerized twill fabric) were prepared wi...

  5. Surface Layer Formation When Finish-Hardening Processing of the Parts by Smoothing

    NASA Astrophysics Data System (ADS)

    Belyaev, V. N.; Tatarkin, E. Ju

    2016-04-01

    Problems of surface layer formation of the parts, when hydraulic smoothing, are considered in this work. The results of theoretical and pilot studies of smoothing in case of nanocarbons and copper salts introduction into the process liquid are given. The influence dependences of the processing modes on roughness and microhardness of surface layer are defined.

  6. Distributions of surface-layer buoyance versus lifting condensation level over a heterogeneous land surface

    SciTech Connect

    Schrieber, K.; Zhang, Qing; Stull, R.

    1996-04-15

    Onset and coverage of small cumulus clouds depend on the relative abundance of surface-layer air parcels possessing favorable buoyancy and moisture - two variables that are coupled through the surface energy budget. This abundance is described using a joint frequency distribution (JFD) as a function of virtual potential temperature {theta}{sub v} and height of the lifting condensation level z{sub LCL}. It is shown analytically that the shape and spread of this JFD depends on the ranges of Bowen ratios and solar forcings (albedoes, cloud shading, etc.) that exist within a domain of heterogeneous land use. To sample the character of such JFDs in the real atmosphere, a case study is presented using turbulence data gathered by aircraft flying in the surface layer of southwest France. This case study includes 4 days of clear skies during the Hydrologic Atmospheric Pilot Experiment (HAPEX) of 1986. The full flight track during HAPEX overflew a wide range of land use including evergreen forest, corn, vineyards, pastures, and irrigated fields over varied topography. The JFDs from these full tracks are found to be quite complex, being frequently multimodal with a convoluted perimeter. However, when a full track is broken into segments, each over a subdomain of quasi-homogeneous land use, the resulting segment JFDs are mono-modal with simpler topology. Such a characterization of JFDs provides guidance toward eventual subgrid cumulus parameterization in large-scale forecast models, with associated impacts in aviation forecasting, pollutant venting and chemical reactions, verticle dispersion and turbulence modulation, and radiation balance in climate-change models. 48 refs., 17 figs., 7 tabs.

  7. Structure, surface interactions, and compressibility of bacterial S-layers through scanning force microscopy and the surface force apparatus.

    PubMed

    Martín-Molina, Alberto; Moreno-Flores, Susana; Perez, Eric; Pum, Dietmar; Sleytr, Uwe B; Toca-Herrera, José L

    2006-03-01

    Two-dimensional crystalline bacterial surface layers (S-layers) are found in a broad range of bacteria and archaea as the outermost cell envelope component. The self-assembling properties of the S-layers permit them to recrystallize on solid substrates. Beyond their biological interest as S-layers, they are currently used in nanotechnology to build supramolecular structures. Here, the structure of S-layers and the interactions between them are studied through surface force techniques. Scanning force microscopy has been used to study the structure of recrystallized S-layers from Bacillus sphaericus on mica at different 1:1 electrolyte concentrations. They give evidence of the two-dimensional organization of the proteins and reveal small corrugations of the S-layers formed on mica. The lattice parameters of the S-layers were a=b=14 nm, gamma=90 degrees and did not depend on the electrolyte concentration. The interaction forces between recrystallized S-layers on mica were studied with the surface force apparatus as a function of electrolyte concentration. Force measurements show that electrostatic and steric interactions are dominant at long distances. When the S-layers are compressed they exhibit elastic behavior. No adhesion between recrystallized layers takes place. We report for the first time, to our knowledge, the value of the compressibility modulus of the S-layer (0.6 MPa). The compressibility modulus is independent on the electrolyte concentration, although loads of 20 mN m-1 damage the layer locally. Control experiments with denatured S-proteins show similar elastic properties under compression but they exhibit adhesion forces between proteins, which were not observed in recrystallized S-layers. PMID:16361337

  8. Layered devices having surface curvature and method of constructing same

    DOEpatents

    Woodbury, Richard C.; Perkins, Raymond T.; Thorne, James M.

    1989-01-01

    A method of treating a substrate having first and second sides with corresponding oppositely facing first and second surfaces, to produce curvature in the first surface. The method includes the steps of removing material, according to a predetermined pattern, from the second side of the substrate, and applying a stress-producing film of material to at least one surface of the substrate to thereby cause the substrate to bend to produce the desired curvature in the first surface.

  9. Turbulent boundary layer over solid and porous surfaces with small roughness

    NASA Technical Reports Server (NTRS)

    Kong, F. Y.; Schetz, J. A.; Collier, F.

    1982-01-01

    Skin friction and profiles of mean velocity, axial and normal turbulence intensity, and Reynolds stress in the untripped boundary layer were measured directly on a large diameter, axisymmetric body with: (1) a smooth, solid surface; (2) a sandpaper-roughened, solid surface; (3) a sintered metal, porous surface; (4) a smooth, perforated titanium surface; (5) a rough solid surface made of fine, diffusion bonded screening, and (6) a rough, porous surface of the same screening. Results obtained for each of these surfaces are discussed. It is shown that a rough, porous wall simply does not influence the boundary layer in the same way as a rough solid wall. Therefore, turbulent transport models for boundary layers over porous surfaces either with or without injection or suction, must include both surface roughness and porosity effects.

  10. Influence of ultrathin water layer on the van der Waals/Casimir force between gold surfaces

    SciTech Connect

    Palasantzas, G.; Zwol, P. J. van; Svetovoy, V. B.

    2009-06-15

    In this paper we investigate the influence of ultrathin water layer ({approx}1-1.5 nm) on the van der Waals/Casimir force between gold surfaces. Adsorbed water is inevitably present on gold surfaces at ambient conditions as jump-up-to contact during adhesion experiments demonstrate. Calculations based on the Lifshitz theory give very good agreement with the experiment in the absence of any water layer for surface separations d > or approx. 10 nm. However, a layer of thickness h < or approx. 1.5 nm is allowed by the error margin in force measurements. At shorter separations, d < or approx. 10 nm, the water layer can have a strong influence as calculations show for flat surfaces. Nonetheless, in reality the influence of surface roughness must also be considered, and it can overshadow any water layer influence at separations comparable to the total sphere-plate rms roughness w{sub shp}+w.

  11. Effect of impurities in the description of surface nanobubbles: Role of nonidealities in the surface layer

    NASA Astrophysics Data System (ADS)

    Das, Siddhartha

    2011-06-01

    In a recent study [S. Das, J. H. Snoeijer, and D. Lohse, Phys. Rev. E1539-375510.1103/PhysRevE.82.056310 82, 056310 (2010)], we provided quantitative demonstration of the conjecture [W. A. Ducker, LangmuirLANGD50743-746310.1021/la902011v 25, 8907 (2009)] that the presence of impurities at the surface layer (or the air-water interface) of surface nanobubbles can substantially lower the gas-side contact angle and the Laplace pressure of the nanobubbles. Through an analytical model for any general air-water interface without nonideality effects, we showed that a large concentration of soluble impurities at the air-water interface of the nanobubbles ensures significantly small contact angles (matching well with the experimental results) and Laplace pressure (though large enough to forbid stability). In this paper this general model is extended to incorporate the effect of nonidealities at the air-water interface in impurity-induced alteration of surface nanobubble properties. Such nonideality effects arise from finite enthalpy or entropy of mixing or finite ionic interactions of the impurity molecules at the nanobubble air-water interface and ensure significant lowering of the nanobubble contact angle and Laplace pressure even at relatively small impurity coverage. In fact for impurity molecules that show enhanced tendency to get adsorbed at the nanobubble air-water interface from the bulk phase, impurity-induced lowering of the nanobubble contact angle is witnessed for extremely small bulk concentration. Surface nanobubble experiments being typically performed in an ultraclean environment, the bulk concentration of impurities is inevitably very small, and in this light the present calculations can be viewed as a satisfactory explanation of the conjecture that impurities, even in trace concentration, have significant impact on surface nanobubbles.

  12. The surface modified composite layer formation with boron carbide particles on magnesium alloy surfaces through pulse gas tungsten arc treatment

    NASA Astrophysics Data System (ADS)

    Ding, W. B.; Jiang, H. Y.; Zeng, X. Q.; Li, D. H.; Yao, S. S.

    2007-02-01

    A novel fabrication process of surface modified composite layer by pulse current gas tungsten arc (GTA) surface modification process was used to deposit B 4C particles on the surface of magnesium alloy AZ31. This method is an effective technique in producing a high performance surface modified composite layer. During the pulse current GTA surface modification process, considerable convection can exist in the molten pool due to various driving forces and the pulse current could cause violent stirring in the molten pool, and the large temperature gradient across the boundary between the GTA modified surface and matrix metal resulted in rapid resolidification with high cooling rates in the molten pool, so that the process result notable grain refinement in the GTA surface modified composite layer. The hardness and wear resistance of the GTA surface modified composite layer are superior to that of as-received magnesium alloy AZ31. The hardness values and wear resistance of GTA surface modified composite layer depend on the GTA process parameters and the B 4C particles powder concentration and distribution. The optimum processing parameters for the formation of a homogeneous crack/defect-free and grain refinement microstructure were established.

  13. Surface Passivation by Quantum Exclusion Using Multiple Layers

    NASA Technical Reports Server (NTRS)

    Hoenk, Michael E. (Inventor)

    2015-01-01

    A semiconductor device has a multilayer doping to provide improved passivation by quantum exclusion. The multilayer doping includes at least two doped layers fabricated using MBE methods. The dopant sheet densities in the doped layers need not be the same, but in principle can be selected to be the same sheet densities or to be different sheet densities. The electrically active dopant sheet densities are quite high, reaching more than 1.times.10.sup.14 cm.sup.-2, and locally exceeding 10.sup.22 per cubic centimeter. It has been found that silicon detector devices that have two or more such dopant layers exhibit improved resistance to degradation by UV radiation, at least at wavelengths of 193 nm, as compared to conventional silicon p-on-n devices.

  14. Bonding of copper surface in ambient air using propylene carbonate as passivation layer

    NASA Astrophysics Data System (ADS)

    Zhu, Zhiyuan; Yu, Min; Phillips, Oluwadamilola; Liu, Lisha; Jin, Yufeng

    2015-07-01

    Bonding of a copper surface in a nonvacuum environment has been studied for the purpose of reducing manufacturing costs. Cu-Cu bonding in ambient air is demonstrated by using propylene carbonate (PPC) as a passivation layer. The decomposition of the PPC passivation layer during bonding would protect the copper surface from oxidation by providing a shielding gas atmosphere between the copper surface and the air. Further, the PPC passivation layer would also overcome the degradation of copper surface during storage in the atmosphere.

  15. A literature review of surface alteration layer effects on waste glass behavior

    SciTech Connect

    Feng, X.; Cunnane, J.C.; Bates, J.K.

    1993-01-01

    When in contact with an aqueous solution, nuclear waste glass is subject to a chemical attack that results in progressive alteration. During tills alteration, constituent elements of the glass pass into the solution; elements initially in solution diffuse into, or are adsorbed onto, the solid; and new phases appear. This results in the formation of surface layers on the reacted glass. The glass corrosion and radionuclide release can be better understood by investigating these surface layer effects. In the past decade, there have been numerous studies regarding the effects of surface layers on glass reactions. This paper presents a systematic analysis and summary of the past knowledge regarding the effects of surface layers on glass-water interaction. This paper describes the major formation mechanisms of surface layers; reviews the role of surface layers in controlling mass transport and glass reaction affinity (through crystalline phases, an amorphous silica, a gel layer, or all the components in the glass); and discusses how the surface layers contribute to the retention of radionuclides during glass dissolution.

  16. A literature review of surface alteration layer effects on waste glass behavior

    SciTech Connect

    Feng, X.; Cunnane, J.C.; Bates, J.K.

    1993-05-01

    When in contact with an aqueous solution, nuclear waste glass is subject to a chemical attack that results in progressive alteration. During tills alteration, constituent elements of the glass pass into the solution; elements initially in solution diffuse into, or are adsorbed onto, the solid; and new phases appear. This results in the formation of surface layers on the reacted glass. The glass corrosion and radionuclide release can be better understood by investigating these surface layer effects. In the past decade, there have been numerous studies regarding the effects of surface layers on glass reactions. This paper presents a systematic analysis and summary of the past knowledge regarding the effects of surface layers on glass-water interaction. This paper describes the major formation mechanisms of surface layers; reviews the role of surface layers in controlling mass transport and glass reaction affinity (through crystalline phases, an amorphous silica, a gel layer, or all the components in the glass); and discusses how the surface layers contribute to the retention of radionuclides during glass dissolution.

  17. Layer-by-layer fabrication of supramolecular dyes on TiO2 surfaces for optoelectronic applications

    NASA Astrophysics Data System (ADS)

    Kong, Xiaoqing; Maguire, Shawn; Lye, Diane; Weck, Marcus; Lee, Stephanie

    We present a modular layer-by-layer approach based on metal coordination chemistry to assemble supramolecular dyes exhibiting increased absorption in the visible range on electrode surfaces. Specifically, palladiated bis-pincer complexes (Pd-BPCs) were employed as linkers between pyridyl-terminated organic molecules via dative bonding. By alternately immersing mesoporous TiO2-coated glass substrates in solutions containing dissolved zinc porphyin (ZnP) and Pd-BPCs, supramolecular dyes were assembled layer-by-layer on the TiO2 surfaces. UV-visible absorption spectra of these assembled structures revealed a linear increase in the Soret and Q bands of ZnP after each immersion of the substrate in the ZnP solution. Coordination of the ZnP layers with Pd-BPC resulted in a slight red shift (<10 nm) of the absorption bands. The modular nature of the assembly process afforded the incorporation of other pyridyl-terminated organic molecules in specific layers of the supramolecular assemblies. By assembling unique organic dyes that absorb different wavelengths of light, we expect to expand light absorption across the visible region of the solar spectrum for solar cell applications.

  18. Adapting the Electrospinning Process to Provide Three Unique Environments for a Tri-layered In Vitro Model of the Airway Wall.

    PubMed

    Bridge, Jack C; Aylott, Jonathan W; Brightling, Christopher E; Ghaemmaghami, Amir M; Knox, Alan J; Lewis, Mark P; Rose, Felicity R A J; Morris, Gavin E

    2015-01-01

    Electrospinning is a highly adaptable method producing porous 3D fibrous scaffolds that can be exploited in in vitro cell culture. Alterations to intrinsic parameters within the process allow a high degree of control over scaffold characteristics including fiber diameter, alignment and porosity. By developing scaffolds with similar dimensions and topographies to organ- or tissue-specific extracellular matrices (ECM), micro-environments representative to those that cells are exposed to in situ can be created. The airway bronchiole wall, comprised of three main micro-environments, was selected as a model tissue. Using decellularized airway ECM as a guide, we electrospun the non-degradable polymer, polyethylene terephthalate (PET), by three different protocols to produce three individual electrospun scaffolds optimized for epithelial, fibroblast or smooth muscle cell-culture. Using a commercially available bioreactor system, we stably co-cultured the three cell-types to provide an in vitro model of the airway wall over an extended time period. This model highlights the potential for such methods being employed in in vitro diagnostic studies investigating important inter-cellular cross-talk mechanisms or assessing novel pharmaceutical targets, by providing a relevant platform to allow the culture of fully differentiated adult cells within 3D, tissue-specific environments. PMID:26275100

  19. Adapting the Electrospinning Process to Provide Three Unique Environments for a Tri-layered In Vitro Model of the Airway Wall

    PubMed Central

    Bridge, Jack C.; Aylott, Jonathan W.; Brightling, Christopher E.; Ghaemmaghami, Amir M.; Knox, Alan J.; Lewis, Mark P.; Rose, Felicity R.A.J.; Morris, Gavin E.

    2015-01-01

    Electrospinning is a highly adaptable method producing porous 3D fibrous scaffolds that can be exploited in in vitro cell culture. Alterations to intrinsic parameters within the process allow a high degree of control over scaffold characteristics including fiber diameter, alignment and porosity. By developing scaffolds with similar dimensions and topographies to organ- or tissue-specific extracellular matrices (ECM), micro-environments representative to those that cells are exposed to in situ can be created. The airway bronchiole wall, comprised of three main micro-environments, was selected as a model tissue. Using decellularized airway ECM as a guide, we electrospun the non-degradable polymer, polyethylene terephthalate (PET), by three different protocols to produce three individual electrospun scaffolds optimized for epithelial, fibroblast or smooth muscle cell-culture. Using a commercially available bioreactor system, we stably co-cultured the three cell-types to provide an in vitro model of the airway wall over an extended time period. This model highlights the potential for such methods being employed in in vitro diagnostic studies investigating important inter-cellular cross-talk mechanisms or assessing novel pharmaceutical targets, by providing a relevant platform to allow the culture of fully differentiated adult cells within 3D, tissue-specific environments. PMID:26275100

  20. Surface Layering at the Mercury-Electrolyte Interface

    SciTech Connect

    Ocko, B.M.; Elsen, A.; Murphy, B.M.; Tamam, L.; Deutsch, M.; Kuzmenko, I.; Magnussen, O.M.

    2010-03-12

    X-ray reflectometry reveals atomic layering at a liquid-liquid interface--mercury in a 0.01 M NaF solution. The interface width exceeds capillary wave theory predictions and displays an anomalous dependence on the voltage applied across it, displaying a minimum positive of the potential of zero charge. The latter is explained by electrocapillary effects and an additional intrinsic broadening of the interface profile, tentatively assigned to polarization of the conduction electrons due to the electric field of the electrochemical double layer at the interface.

  1. Expansible apparatus for removing the surface layer from a concrete object

    DOEpatents

    Allen, Charles H.

    1979-01-01

    A method and apparatus for removing the surface layer from a concrete object. The method consists of providing a hole having a circular wall in the surface layer of the object, the hole being at least as deep as the thickness of the surface layer to be removed, and applying an outward wedging pressure on the wall of the hole sufficient to spall the surface layer around the hole. By the proper spacing of an appropriate number of holes, it is possible to remove the entire surface layer from an object. The apparatus consists of an elongated tubular-shaped body having a relatively short handle with a solid wall at one end, the wall of the remainder of the body containing a plurality of evenly spaced longitudinal cuts to form a relatively long expandable section, the outer end of the expandable section having an expandable, wedge-shaped spalling edge extending from the outer surface of the wall, perpendicular to the longitudinal axis of the body, and expanding means in the body for outwardly expanding the expandable section and forcing the spalling edge into the wall of a hole with sufficient outward pressure to spall away the surface layer of concrete. The method and apparatus are particularly suitable for removing surface layers of concrete which are radioactively contaminated.

  2. Modifying of Cotton Fabric Surface with Nano-ZnO Multilayer Films by Layer-by-Layer Deposition Method.

    PubMed

    Uğur, Sule S; Sarıışık, Merih; Aktaş, A Hakan; Uçar, M Ciğdem; Erden, Emre

    2010-01-01

    ZnO nanoparticle-based multilayer nanocomposite films were fabricated on cationized woven cotton fabrics via layer-by-layer molecular self-assembly technique. For cationic surface charge, cotton fabrics were pretreated with 2,3-epoxypropyltrimethylammonium chloride (EP3MAC) by pad-batch method. XPS and SEM were used to examine the deposited nano-ZnO multilayer films on the cotton fabrics. The nano-ZnO films deposited on cotton fabrics exhibited excellent antimicrobial activity against Staphylococcus aureus bacteria. The results also showed that the coated fabrics with nano-ZnO multilayer films enhanced the protection of cotton fabrics from UV radiation. Physical tests (tensile strength of weft and warp yarns, air permeability and whiteness values) were performed on the fabrics before and after the treatment with ZnO nanoparticles to evaluate the effect of layer-by-layer (LbL) process on cotton fabrics properties. PMID:20596450

  3. Modifying of Cotton Fabric Surface with Nano-ZnO Multilayer Films by Layer-by-Layer Deposition Method

    PubMed Central

    2010-01-01

    ZnO nanoparticle–based multilayer nanocomposite films were fabricated on cationized woven cotton fabrics via layer-by-layer molecular self-assembly technique. For cationic surface charge, cotton fabrics were pretreated with 2,3-epoxypropyltrimethylammonium chloride (EP3MAC) by pad-batch method. XPS and SEM were used to examine the deposited nano-ZnO multilayer films on the cotton fabrics. The nano-ZnO films deposited on cotton fabrics exhibited excellent antimicrobial activity against Staphylococcus aureus bacteria. The results also showed that the coated fabrics with nano-ZnO multilayer films enhanced the protection of cotton fabrics from UV radiation. Physical tests (tensile strength of weft and warp yarns, air permeability and whiteness values) were performed on the fabrics before and after the treatment with ZnO nanoparticles to evaluate the effect of layer-by-layer (LbL) process on cotton fabrics properties. PMID:20596450

  4. Layer-by-layer modification of high surface curvature nanoparticles with weak polyelectrolytes using a multiphase solvent precipitation process.

    PubMed

    Nagaraja, Ashvin T; You, Yil-Hwan; Choi, Jeong-Wan; Hwang, Jin-Ha; Meissner, Kenith E; McShane, Michael J

    2016-03-15

    The layer-by-layer modification of ≈5 nm mercaptocarboxylic acid stabilized gold nanoparticles was studied in an effort to illustrate effective means to overcome practical issues in handling and performing surface modification of such extremely small materials. To accomplish this, each layer deposition cycle was separated into a multi-step process wherein solution pH was controlled in two distinct phases of polyelectrolyte adsorption and centrifugation. Additionally, a solvent precipitation step was introduced to make processing more amenable by concentrating the sample and exchanging solution pH before ultracentrifugation. The pH-dependent assembly on gold nanoparticles was assessed after each layer deposition cycle by monitoring the plasmon peak absorbance location, surface charge, and the percentage of nanoparticles recovered. The selection of solution pH during the adsorption phase was found to be a critical parameter to enhance particle recovery and maximize surface charge when coating with weak polyelectrolytes. One bilayer was deposited with a high yield and the modified particles exhibited enhanced colloidal stability across a broad pH range and increased ionic strength. These findings support the adoption of this multi-step processing approach as an effective and generalizable approach to improve stability of high surface curvature particles. PMID:26771506

  5. Method for removing surface-damaged layers from nickel alloys

    NASA Technical Reports Server (NTRS)

    Fawley, R. W.

    1968-01-01

    Electrical discharge machining /EDM/ damaged layer can be effectively removed from Rene 41, Inconel 625, Inconel 718, and Monel K-500 by abrasive-grit blasting or electropolishing /at room temperature/ at a current density of 5A/inches squared in a water solution of phosphoric and sulfuric acids.

  6. Study of microstructure of surface layers of low-carbon steel after turning and ultrasonic finishing

    NASA Astrophysics Data System (ADS)

    Kovalevskaya, Zh. G.; Ivanov, Yu. F.; Perevalova, O. B.; Klimenov, V. A.; Uvarkin, P. V.

    2013-01-01

    Profilometry and optical and transmission electron microscopy are used to examine the microstructure of surface layers of a low-carbon ferrite-pearlite steel subjected to turning and ultrasonic finishing. It is shown that turning peaks and valleys have different microstructures, which stipulates manifestation of technological hereditary when processing surfaces of machined parts. Ultrasonic finishing causes the severe plastic deformation of the surface layer, which favors the elimination of a technological heredity that is acquired during turning.

  7. Effect of the interplay between protein and surface on the properties of adsorbed protein layers.

    PubMed

    Ouberai, Myriam M; Xu, Kairuo; Welland, Mark E

    2014-08-01

    Although protein adsorption to surface is a common phenomenon, investigation of the process is challenging due to the complexity of the interplay between external factors, protein and surface properties. Therefore experimental approaches have to measure the properties of adsorbed protein layers with high accuracy in order to achieve a comprehensive description of the process. To this end, we used a combination of two biosensing techniques, dual polarization interferometry and quartz crystal microbalance with dissipation. From this, we are able to extract surface coverage values, layer structural parameters, water content and viscoelastic properties to examine the properties of protein layers formed at the liquid/solid interface. Layer parameters were examined upon adsorption of proteins of varying size and structural properties, on surfaces with opposite polarity. We show that "soft" proteins such as unfolded α-synuclein and high molecular weight albumin are highly influenced by the surface polarity, as they form a highly diffuse and hydrated layer on the hydrophilic silica surface as opposed to the denser, less hydrated layer formed on a hydrophobic methylated surface. These layer properties are a result of different orientations and packing of the proteins. By contrast, lysozyme is barely influenced by the surface polarity due to its intrinsic structural stability. Interestingly, we show that for a similar molecular weight, the unfolded α-synuclein forms a layer with the highest percentage of solvation not related to surface coverage but resulting from the highest water content trapped within the protein. Together, these data reveal a trend in layer properties highlighting the importance of the interplay between protein and surface for the design of biomaterials. PMID:24780165

  8. Evolution of the surface area of a snow layer

    SciTech Connect

    Hanot, L.; Domine, F.

    1999-12-01

    Atmospheric trace gases can partition between the atmosphere and the snow surface. Because snow has a large surface-to-volume ratio, an important interaction potential between ice and atmospheric trace gases exists. Quantifying this partitioning requires the knowledge of the surface area (SA) of snow. Eleven samples were taken from a 50 cm thick snow fall at Col de Porte, near Grenoble (French Alps) between January 20 and February 4, 1998. Fresh snow and 3, 8, and 15-day-old snow were sampled at three different depths. Surface hoar, formed after the fall, was also sampled. Air and surface snow temperature, snow density, and snow fall rate were measured. Snow temperature always remained below freezing. Snow SA was measured using methane adsorption at 77.15 K. Values ranged from 2.25 m{sup 2}/g for fresh snow to 0.25 m{sup 2}/g for surface hoar and surface snow after 15 days. These values are much too high to be explained by the macroscopic aspect of snow crystals, and microstructures such as small rime droplets must have been present. Large decrease in SA with time were observed. The first meter of snowpack had a total surface area of about 50,000 m{sup 2} per m{sup 2} of ground. Reduction in SA will lead to the emission of adsorbed species by the snowpack, with possible considerable increase in atmospheric concentrations.

  9. 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. PMID:2390765

  10. Relations among stability parameters in the stable surface layer: Golder curves revisited

    NASA Astrophysics Data System (ADS)

    Sharan, Maithili; Rama Krishna, T. V. B. P. S.; Panda, Jagabandhu

    A nomogram was prepared by [Golder, 1972. Boundary Layer Meteorology 3, 47-58] to compute the surface layer parameters in stable conditions. This note revisits the Golder's curves and examines the methodology underlying their derivation in stable conditions. The inherent limitation in the methodology used for construction of Golder's curves was also noticed by Trombetti et al. (1986). Surface layer fluxes computed using the parameters derived from modified curves are found to be closer to the turbulence measurements from CASES-99 experiment for stable conditions than those calculated from the [Golder, 1972. Boundary Layer Meteorology 3, 47-58] curves.

  11. Layered Gold and Titanium Dioxide Substrates for Improved Surface Enhanced Raman Spectroscopic Sensing.

    PubMed

    Strobbia, Pietro; Henegar, Alex J; Gougousi, Theodosia; Cullum, Brian M

    2016-08-01

    This manuscript describes a simple process for fabricating gold-based, multi-layered, surface-enhanced Raman scattering (SERS) substrates that can be applied to a variety of different nanostructures, while still providing multi-layer enhancement factors comparable to those previously achieved only with optimized silver/silver oxide/silver substrates. In particular, gold multi-layered substrates generated by atomic layer deposition (ALD) have been fabricated and characterized in terms of their optimal performance, revealing multi-layer enhancements of 2.3-fold per spacer layer applied. These substrates were fabricated using TiO2 as the dielectric spacer material between adjacent gold layers, with ALD providing a conformal thin film with high surface coverage and low thickness. By varying the spacer layer thicknesses from sub-monolayer (non-contiguous) films through multiple TiO2 layer thick films, the non-monotonic spacer layer thickness response has been elucidated, revealing the importance of thin, contiguous dielectric spacer layers for optimal enhancement. Furthermore, the extended shelf life of these gold multi-layered substrates was characterized, demonstrating usable lifetimes (i.e. following storage in ambient conditions) of greater than five months, with the further potential for simple limited electrochemical regeneration even after this time. PMID:27329834

  12. Origin and consequences of silicate glass passivation by surface layers

    NASA Astrophysics Data System (ADS)

    Gin, Stéphane; Jollivet, Patrick; Fournier, Maxime; Angeli, Frédéric; Frugier, Pierre; Charpentier, Thibault

    2015-02-01

    Silicate glasses are durable materials, but are they sufficiently durable to confine highly radioactive wastes for hundreds of thousands years? Addressing this question requires a thorough understanding of the mechanisms underpinning aqueous corrosion of these materials. Here we show that in silica-saturated solution, a model glass of nuclear interest corrodes but at a rate that dramatically drops as a passivating layer forms. Water ingress into the glass, leading to the congruent release of mobile elements (B, Na and Ca), is followed by in situ repolymerization of the silicate network. This material is at equilibrium with pore and bulk solutions, and acts as a molecular sieve with a cutoff below 1 nm. The low corrosion rate resulting from the formation of this stable passivating layer enables the objective of durability to be met, while progress in the fundamental understanding of corrosion unlocks the potential for optimizing the design of nuclear glass-geological disposal.

  13. Origin and consequences of silicate glass passivation by surface layers

    PubMed Central

    Gin, Stéphane; Jollivet, Patrick; Fournier, Maxime; Angeli, Frédéric; Frugier, Pierre; Charpentier, Thibault

    2015-01-01

    Silicate glasses are durable materials, but are they sufficiently durable to confine highly radioactive wastes for hundreds of thousands years? Addressing this question requires a thorough understanding of the mechanisms underpinning aqueous corrosion of these materials. Here we show that in silica-saturated solution, a model glass of nuclear interest corrodes but at a rate that dramatically drops as a passivating layer forms. Water ingress into the glass, leading to the congruent release of mobile elements (B, Na and Ca), is followed by in situ repolymerization of the silicate network. This material is at equilibrium with pore and bulk solutions, and acts as a molecular sieve with a cutoff below 1 nm. The low corrosion rate resulting from the formation of this stable passivating layer enables the objective of durability to be met, while progress in the fundamental understanding of corrosion unlocks the potential for optimizing the design of nuclear glass-geological disposal. PMID:25695377

  14. Origin and consequences of silicate glass passivation by surface layers.

    PubMed

    Gin, Stéphane; Jollivet, Patrick; Fournier, Maxime; Angeli, Frédéric; Frugier, Pierre; Charpentier, Thibault

    2015-01-01

    Silicate glasses are durable materials, but are they sufficiently durable to confine highly radioactive wastes for hundreds of thousands years? Addressing this question requires a thorough understanding of the mechanisms underpinning aqueous corrosion of these materials. Here we show that in silica-saturated solution, a model glass of nuclear interest corrodes but at a rate that dramatically drops as a passivating layer forms. Water ingress into the glass, leading to the congruent release of mobile elements (B, Na and Ca), is followed by in situ repolymerization of the silicate network. This material is at equilibrium with pore and bulk solutions, and acts as a molecular sieve with a cutoff below 1 nm. The low corrosion rate resulting from the formation of this stable passivating layer enables the objective of durability to be met, while progress in the fundamental understanding of corrosion unlocks the potential for optimizing the design of nuclear glass-geological disposal. PMID:25695377

  15. Shape-selective sieving layers on an oxide catalyst surface.

    PubMed

    Canlas, Christian P; Lu, Junling; Ray, Natalie A; Grosso-Giordano, Nicolas A; Lee, Sungsik; Elam, Jeffrey W; Winans, Randall E; Van Duyne, Richard P; Stair, Peter C; Notestein, Justin M

    2012-12-01

    New porous materials such as zeolites, metal-organic frameworks and mesostructured oxides are of immense practical utility for gas storage, separations and heterogeneous catalysis. Their extended pore structures enable selective uptake of molecules or can modify the product selectivity (regioselectivity or enantioselectivity) of catalyst sites contained within. However, diffusion within pores can be problematic for biomass and fine chemicals, and not all catalyst classes can be readily synthesized with pores of the correct dimensions. Here, we present a novel approach that adds reactant selectivity to existing, non-porous oxide catalysts by first grafting the catalyst particles with single-molecule sacrificial templates, then partially overcoating the catalyst with a second oxide through atomic layer deposition. This technique is used to create sieving layers of Al(2)O(3) (thickness, 0.4-0.7 nm) with 'nanocavities' (<2 nm in diameter) on a TiO(2) photocatalyst. The additional layers result in selectivity (up to 9:1) towards less hindered reactants in otherwise unselective, competitive photocatalytic oxidations and transfer hydrogenations. PMID:23174984

  16. Shape-selective sieving layers on an oxide catalyst surface

    NASA Astrophysics Data System (ADS)

    Canlas, Christian P.; Lu, Junling; Ray, Natalie A.; Grosso-Giordano, Nicolas A.; Lee, Sungsik; Elam, Jeffrey W.; Winans, Randall E.; van Duyne, Richard P.; Stair, Peter C.; Notestein, Justin M.

    2012-12-01

    New porous materials such as zeolites, metal-organic frameworks and mesostructured oxides are of immense practical utility for gas storage, separations and heterogeneous catalysis. Their extended pore structures enable selective uptake of molecules or can modify the product selectivity (regioselectivity or enantioselectivity) of catalyst sites contained within. However, diffusion within pores can be problematic for biomass and fine chemicals, and not all catalyst classes can be readily synthesized with pores of the correct dimensions. Here, we present a novel approach that adds reactant selectivity to existing, non-porous oxide catalysts by first grafting the catalyst particles with single-molecule sacrificial templates, then partially overcoating the catalyst with a second oxide through atomic layer deposition. This technique is used to create sieving layers of Al2O3 (thickness, 0.4-0.7 nm) with ‘nanocavities’ (<2 nm in diameter) on a TiO2 photocatalyst. The additional layers result in selectivity (up to 9:1) towards less hindered reactants in otherwise unselective, competitive photocatalytic oxidations and transfer hydrogenations.

  17. Transient Heat Transfer in a Semitransparent Radiating Layer with Boundary Convection and Surface Reflections

    NASA Technical Reports Server (NTRS)

    Siegel, Robert

    1996-01-01

    Surface convection and refractive index are examined during transient radiative heating or cooling of a grey semitransparent layer with internal absorption, emission and conduction. Each side of the layer is exposed to hot or cold radiative surroundings, while each boundary is heated or cooled by convection. Emission within the layer and internal reflections depend on the layer refractive index. The reflected energy and heat conduction distribute energy across the layer and partially equalize the transient temperature distributions. Solutions are given to demonstrate the effect of radiative heating for layers with various optical thicknesses, the behavior of the layer heated by radiation on one side and convectively cooled on the other, and a layer heated by convection while being cooled by radiation. The numerical method is an implicit finite difference procedure with non-uniform space and time increments. The basic method developed in earlier work is expanded to include external convection and incident radiation.

  18. Microporous structure with layered interstitial surface treatment, and method and apparatus for preparation thereof

    NASA Technical Reports Server (NTRS)

    Koontz, Steven L. (Inventor)

    1992-01-01

    A microporous structure with layered interstitial surface treatments, and the method and apparatus for its preparation are disclosed. The structure is prepared by sequentially subjecting a uniformly surface treated structure to atomic oxygen treatment to remove an outer layer of surface treatment to a generally uniform depth, and then surface treating the so exposed layer with another surface treating agent. The atomic oxygen/surface treatment steps may optionally be repeated, each successive time to a lesser depth, to produce a microporous structure having multilayered surface treatments. The apparatus employs at least one side arm from a main oxygen-containing chamber. The side arm has characteristic relaxation times such that a uniform atomic oxygen dose rate is delivered to a specimen positioned transversely in the side arm spaced from the main gas chamber.

  19. Microporous structure with layered interstitial surface treatment, and method and apparatus for preparation thereof

    NASA Technical Reports Server (NTRS)

    Koontz, Steven L. (Inventor)

    1994-01-01

    A microporous structure with layered interstitial surface treatments, and method and apparatus for preparation thereof is presented. The structure is prepared by sequentially subjecting a uniformly surface-treated structure to atomic oxygen treatment to remove an outer layer of surface treatment to a generally uniform depth, and then surface treating the so exposed layer with another surface treating agent. The atomic oxygen/surface treatment steps may optionally be repeated, each successive time to a lesser depth, to produce a microporous structure having multilayered surface treatments. The apparatus employs at least one side arm from a main atomic oxygen-containing chamber. The side arm has characteristic relaxation times such that a uniform atomic oxygen dose rate is delivered to a specimen positioned transversely in the side arm spaced from the main gas chamber.

  20. Surface double-layer structure in (110) oriented BiFeO{sub 3} thin film

    SciTech Connect

    Yang, Tieying; Zhang, Xingmin; Gao, Xingyu; Li, Zhong; Li, Xiaolong; Wang, Can; Feng, Yu; Guo, Haizhong; Jin, Kuijuan

    2014-11-17

    Surface double-layer structure different from the interior was found in BiFeO{sub 3} thin film grown on SrRuO{sub 3} covered SrTiO{sub 3} (110) substrate by pulsed laser deposition. It was shown that BiFeO{sub 3} film exhibits epitaxial phase with single domain. X-ray reflectivity and X-ray photoelectron spectroscopy results revealed a skin layer of less than 1 nm with a reduced electron density and different surface state. Grazing incidence x-ray diffraction convinced a surface multi-domain structure of several nm beneath the surface skin layer. The double-layer near surface structure would be originated from the large depolarization field produced by the single-domain structure with strain.

  1. Surface plasmon sensing with different metals in single and double layer configurations.

    PubMed

    Nesterenko, Dmitry V; Saif-ur-Rehman; Sekkat, Zouheir

    2012-09-20

    The resolution of surface plasmon resonance sensors in the geometry of Kretschmann is estimated by numerical simulation for different thicknesses of combinations of silver (Ag), copper, and aluminum (Al) metallic layers with a gold coating layer at set of wavelengths in cases of detecting the change of the refractive index of the bulk medium and the change in optical thickness of an adsorption layer. The lowest resolution among the examined combinations of the sensors is achieved with a single Al layer for ultraviolet region and with a single Ag layer for longer wavelengths. PMID:23205393

  2. Cryoscanning electron microscopic study of the surface amorphous layer of articular cartilage.

    PubMed Central

    Kobayashi, S; Yonekubo, S; Kurogouchi, Y

    1995-01-01

    In order to elucidate the structure near the articular surface, frozen unfixed hydrated articular cartilage with subchondral bone from the pig knee was examined using a cryoscanning electron microscope (cryo-SEM). This method is considered to reduce the introduction of artefacts due to fixation and drying. An amorphous layer, without a collagen-fibril network or chondrocytes, covered most of the surface of the cartilage. This layer was termed the surface amorphous layer. It showed various appearances, which were classified into 4 groups. The average thickness of the layer did not differ among the 8 anatomical regions from which the specimens were taken. The thickness of the layer was found to correlate with the type of appearance of the layer. The 4 appearances associated with thicknesses in descending order are: 'streaked', 'foliate', 'spotted', and 'vestigial'. The surface layer observed in the cryo-SEM was thicker than that observed by a conventional SEM. This difference may be attributable to dehydration of the specimen used in specimen preparation for the latter technique. The layer was also observed in articular cartilage taken from human and rabbit knees. The layer was found to be unstable and to have very variable features. Its thickness and appearance may be influenced by various factors such as dehydration, fluid absorption or mechanical stress. Images Fig. 1 Fig. 3 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 Fig. 13 Fig. 14 Fig. 15 Fig. 16 Fig. 17 Fig. 18 Fig. 19 PMID:7592006

  3. Apical localization of the coxsackie-adenovirus receptor by glycosyl-phosphatidylinositol modification is sufficient for adenovirus-mediated gene transfer through the apical surface of human airway epithelia.

    PubMed

    Walters, R W; van't Hof, W; Yi, S M; Schroth, M K; Zabner, J; Crystal, R G; Welsh, M J

    2001-08-01

    In well-differentiated human airway epithelia, the coxsackie B and adenovirus type 2 and 5 receptor (CAR) resides primarily on the basolateral membrane. This location may explain the observation that gene transfer is inefficient when adenovirus vectors are applied to the apical surface. To further test this hypothesis and to investigate requirements and barriers to apical gene transfer to differentiated human airway epithelia, we expressed CAR in which the transmembrane and cytoplasmic tail were replaced by a glycosyl-phosphatidylinositol (GPI) anchor (GPI-CAR). As controls, we expressed wild-type CAR and CAR lacking the cytoplasmic domain (Tailless-CAR). All three constructs enhanced gene transfer with similar efficiencies in fibroblasts. In airway epithelia, GPI-CAR localized specifically to the apical membrane, where it bound adenovirus and enhanced gene transfer to levels obtained when vector was applied to the basolateral membrane. Moreover, GPI-CAR facilitated gene transfer of the cystic fibrosis transmembrane conductance regulator to cystic fibrosis airway epithelia, correcting the Cl(-) transport defect. In contrast, when we expressed wild-type CAR it localized to the basolateral membrane and failed to increase apical gene transfer. Only a small amount of Tailless-CAR resided in the apical membrane, and the effects on apical virus binding and gene transfer were minimal. These data indicate that binding of adenovirus to an apical membrane receptor is sufficient to mediate effective gene transfer to human airway epithelia and that the cytoplasmic domain of CAR is not required for this process. The results suggest that targeting apical receptors in differentiated airway epithelia may be sufficient for gene transfer in the genetic disease cystic fibrosis. PMID:11462042

  4. Apical Localization of the Coxsackie-Adenovirus Receptor by Glycosyl-Phosphatidylinositol Modification Is Sufficient for Adenovirus-Mediated Gene Transfer through the Apical Surface of Human Airway Epithelia

    PubMed Central

    Walters, Robert W.; van't Hof, Wouter; Yi, Su Min P.; Schroth, Mary K.; Zabner, Joseph; Crystal, Ronald G.; Welsh, Michael J.

    2001-01-01

    In well-differentiated human airway epithelia, the coxsackie B and adenovirus type 2 and 5 receptor (CAR) resides primarily on the basolateral membrane. This location may explain the observation that gene transfer is inefficient when adenovirus vectors are applied to the apical surface. To further test this hypothesis and to investigate requirements and barriers to apical gene transfer to differentiated human airway epithelia, we expressed CAR in which the transmembrane and cytoplasmic tail were replaced by a glycosyl-phosphatidylinositol (GPI) anchor (GPI-CAR). As controls, we expressed wild-type CAR and CAR lacking the cytoplasmic domain (Tailless-CAR). All three constructs enhanced gene transfer with similar efficiencies in fibroblasts. In airway epithelia, GPI-CAR localized specifically to the apical membrane, where it bound adenovirus and enhanced gene transfer to levels obtained when vector was applied to the basolateral membrane. Moreover, GPI-CAR facilitated gene transfer of the cystic fibrosis transmembrane conductance regulator to cystic fibrosis airway epithelia, correcting the Cl− transport defect. In contrast, when we expressed wild-type CAR it localized to the basolateral membrane and failed to increase apical gene transfer. Only a small amount of Tailless-CAR resided in the apical membrane, and the effects on apical virus binding and gene transfer were minimal. These data indicate that binding of adenovirus to an apical membrane receptor is sufficient to mediate effective gene transfer to human airway epithelia and that the cytoplasmic domain of CAR is not required for this process. The results suggest that targeting apical receptors in differentiated airway epithelia may be sufficient for gene transfer in the genetic disease cystic fibrosis. PMID:11462042

  5. Functionalised nanoscale coatings using layer-by-layer assembly for imparting antibacterial properties to polylactide-co-glycolide surfaces.

    PubMed

    Gentile, Piergiorgio; Frongia, Maria E; Cardellach, Mar; Miller, Cheryl A; Stafford, Graham P; Leggett, Graham J; Hatton, Paul V

    2015-07-01

    In order to achieve high local biological activity and reduce the risk of side effects of antibiotics in the treatment of periodontal and bone infections, a localised and temporally controlled delivery system is desirable. The aim of this research was to develop a functionalised and resorbable surface to contact soft tissues to improve the antibacterial behaviour during the first week after its implantation in the treatment of periodontal and bone infections. Solvent-cast poly(d,l-lactide-co-glycolide acid) (PLGA) films were aminolysed and then modified by Layer-by-Layer technique to obtain a nano-layered coating using poly(sodium4-styrenesulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) as polyelectrolytes. The water-soluble antibiotic, metronidazole (MET), was incorporated from the ninth layer. Infrared spectroscopy showed that the PSS and PAH absorption bands increased with the layer number. The contact angle values had a regular alternate behaviour from the ninth layer. X-ray Photoelectron Spectroscopy evidenced two distinct peaks, N1s and S2p, indicating PAH and PSS had been introduced. Atomic Force Microscopy showed the presence of polyelectrolytes on the surface with a measured roughness about 10nm after 20 layers' deposition. The drug release was monitored by Ultraviolet-visible spectroscopy showing 80% loaded-drug delivery in 14 days. Finally, the biocompatibility was evaluated in vitro with L929 mouse fibroblasts and the antibacterial properties were demonstrated successfully against the keystone periodontal bacteria Porphyromonas gingivalis, which has an influence on implant failure, without compromising in vitro biocompatibility. In this study, PLGA was successfully modified to obtain a localised and temporally controlled drug delivery system, demonstrating the potential value of LbL as a coating technology for the manufacture of medical devices with advanced functional properties. PMID:25871538

  6. The morphology of an epitaxial Mg Al spinel layer on a sapphire surface

    NASA Astrophysics Data System (ADS)

    Liu, Che-Ming; Chen, Jyh-Chen; Chen, Chun-Jen

    2006-07-01

    In this work an epitaxial Mg-Al spinel layer was successfully grown on a C- and A-plane sapphire single crystal surface by solid-state reactions. When observed by a scanning electron microscope, it can be seen that the morphology of an epitaxial spinel layer surface has a three-fold symmetrical structure. The results of X-ray diffraction analysis indicate that the surface morphology of the epitaxial spinel layer has particular crystallographic directions and the crystallographic directions will be influenced by the orientation of the sapphire substrates.

  7. Shear-induced surface alignment of polymer dispersed liquid crystal microdroplets on the boundary layer

    NASA Technical Reports Server (NTRS)

    Parmar, D. S.; Singh, J. J.

    1993-01-01

    Polymer dispersed liquid crystal thin films have been deposited on a glass substrate, utilizing the processes of polymerization and solvent evaporation induced phase separation. Liquid crystal microdroplets trapped on the upper surface of the thin film respond to the shear stress due to air or gas flow on the surface layer. Response to an applied step shear stress input on the surface layer has been measured by measuring the time response of the transmitted light intensity. Initial results on the measurements of the light transmission as a function of the air flow differential pressure indicate that these systems offer features suitable for boundary layer and gas flow sensors.

  8. Summer Surface Layer Thermal Response to Surface Gravity Waves in the Yellow Sea and the East China Sea

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Han, G.; Deng, Z.; Wang, X.

    2010-12-01

    A three-dimensional ocean model is applied to study the summer surface layer thermal response to surface gravity waves in the Yellow sea and the East China Sea(YES).The parameterization schemes of wave breaking developed by Mellor and Blumberg(2004) and Langmuir circulation developed by Kantha and Clayson(2004) are both included in the Mellor-Yamada turbulence closure model(Mellor and Yamada, 1982). Numerical results show that both surface wave breaking and Langmuir circulation determine the depth of surface boundary layer of temperature in the YES in summer. Langmuir circulation is able to obtain the turbulent kinetic energy injected by breaking waves near the surface and transport it downward to greater depths. A diagnostic analysis of the momentum balance shows that surface gravity waves can decrease the velocity near the surface and make the flow near the surface more homogeneous vertically in the YES. In addition, a diagnostic analysis of the temperature equation has been done for studying the heat budget. Diagnostic results show that more heat that is brought from surface in the YES can been transferred into the deeper layer owing to the surface gravity waves, which can induce local temperature there increase more rapidly. Besides, diagnostic results also suggest that surface gravity waves are likely to decrease upwelling near the bank in the region.

  9. The surface chemistry of GaAs atomic layer epitaxy

    SciTech Connect

    Creighton, J.R.; Banse, B.A.

    1991-01-01

    In this paper we review three proposed mechanisms for GaAs ALE and review or present data support or contradiction of these mechanisms. Surface chemistry results clearly demonstrated that TMGa irreversibly chemisorbs on the Ga-rich GaAs(100) surface. The reactive sticking coefficient (RSC) of TMGa on the adsorbate-free Ga-rich GaAs(100) surface was measured to be {approximately}0.5, conclusively demonstrating that the selective adsorption'' mechanism of ALE is not valid. We describe kinetic evidence for methyl radical desorption in support of the adsorbate inhibition'' mechanism. The methyl radical desorption rates determined by temperature programmed desorption (TPD) demonstrate that desorption is at least a factor of {approximately}10 faster from the As-rich c(2 {times} 8)/(2 {times} 4) surface than from the Ga-rich surface. It is disparity in CH{sub 3} desorption rates between the As-rich and Ga-rich surfaces that is largely responsible for GaAs ALE behavior. A gallium alkyl radical (e.g. MMGa) is also observed during TPD and molecular beam experiments, in partial support of the flux balance'' mechanism. Stoichiometry issues of ALE are also discussed. We have discovered that arsine exposures typical of atmospheric pressure and reduced pressure ALE lead to As coverages {ge} 1 ML, which provides the likely solution to the stoichiometry question regarding the arsine cycle. 32 refs., 6 figs.

  10. MEASUREMENTS OF CONFORMATION CHANGES DURING ADHESION OF LIPID PROTEIN (POLYLYSINE AND S-LAYER) SURFACES

    EPA Science Inventory

    The adhesion forces between various surfaces were measured using the "surface forces apparatus" technique which allows for the thickness of surface layers and the adhesion force between them to be directly measured in controlled vapor or liquid environments. hree types of biologi...

  11. Wettability of terminally anchored polymer brush layers on a polyamide surface.

    PubMed

    Varin, Kari J Moses; Cohen, Yoram

    2014-12-15

    Surface wettability of terminally anchored hydrophilic polymer brush layers on polyamide-silicon (PA-Si) surfaces was evaluated with respect to surface topography at the nanoscale. Hydrophilic polyvinylpyrrolidone (PVP) and polyacrylamide (PAAm) brush layers were synthesized via graft polymerization onto a PA-Si surface previously activated by surface treatment with atmospheric pressure plasma. Hydrophilicity (or wettability) of the PA substrate, as quantified by the free energy of hydration, was increased upon surface coverage with the PVP and PAAm brush layers by 13-24% (-101.4 to -111.3 mJ/m(2)) and 19-37% (-106.1 to -122.4 mJ/m(2)), respectively. Surface hydrophilicity increased with both increasing surface roughness (0.55-2.89 nm and 1.54-5.84 nm for PVP and PAAm, respectively) and polymer volume (1.3×10(6)-7.3×10(6) nm(3)/μm(2) and 3.3×10(6)-2.8×10(7) nm(3)/μm(2) for PVP and PAAm surfaces, respectively). The present study suggests that a specific level of surface wettability can be attained by tailor-designing the polymer brush layer's physicochemical characteristics (e.g., surface roughness, wettability, and polymer water affinity) by adjusting surface topography and surface chemistry, which are controlled by surface activation and polymerization conditions. The above indicates that there is merit in structuring various surfaces with hydrophilic brush layers to increase surface wettability in membrane filtration, biomedical devices, and lubrication applications. PMID:25305445

  12. Upper airway test (image)

    MedlinePlus

    An upper airway biopsy is obtained by using a flexible scope called a bronchoscope. The scope is passed down through ... may be performed when an abnormality of the upper airway is suspected. It may also be performed as ...

  13. [Texture variation of CC 5052 aluminum alloy slab from surface to center layer by XRD].

    PubMed

    Chen, Ming-Biao; Liu, Wen-Chang; Ma, Xiao-Yi; Li, Jian; Yang, Qing-Xiang; Wang, Shan; Ma, Min; Liu, Chang; Zhao, Y M

    2013-05-01

    For improvement of the processing and gaining uniformity texture structure and performance of direct chill cast CCAA 5052 aluminum alloy band after first hot rolling with different reduction, the material was annealed at 454 degrees C and then cold rolling with different reduction was conducted, the texture at surface, quarter and center layer of the sample was tested and examined by X-ray diffraction method, the data calculated using special software and the difference of texture at surface, quarter and center layer was analyzed. There existed an elevated gradient of intensity from surface layer to center layer after cold rolled with less than or equal to 40% reduction, The main texture of beta is stronger mainly due to transformation from remainder exposure, while the goss and remainder is infirm, the state of texture at each layer is close to each other after cold rolling with reduction high than 56.1%. PMID:23905353

  14. Evaluation of parameterization for turbulent fluxes of momentum and heat in stably stratified surface layers

    NASA Astrophysics Data System (ADS)

    Sodemann, H.; Foken, Th.

    2003-04-01

    General Circulation Models calculate the energy exchange between surface and atmosphere by means of parameterisations for turbulent fluxes of momentum and heat in the surface layer. However, currently implemented parameterisations after Louis (1979) create large discrepancies between predictions and observational data, especially in stably stratified surface layers. This work evaluates a new surface layer parameterisation proposed by Zilitinkevich et al. (2002), which was specifically developed to improve energy flux predictions in stable stratification. The evaluation comprises a detailed study of important surface layer characteristics, a sensitivity study of the parameterisation, and a direct comparison to observational data from Antarctica and predictions by the Louis (1979) parameterisation. The stability structure of the stable surface layer was found to be very complex, and strongly influenced fluxes in the surface layer. The sensitivity study revealed that the new parameterisation depends strongly on the ratio between roughness length and roughness temperature, which were both observed to be very variable parameters. The comparison between predictions and measurements showed good agreement for momentum fluxes, but large discrepancies for heat fluxes. A stability dependent evaluation of selected data showed better agreement for the new parameterisation of Zilitinkevich et al. (2002) than for the Louis (1979) scheme. Nevertheless, this comparison underlines the need for more detailed and physically sound concepts for parameterisations of heat fluxes in stably stratified surface layers. Zilitinkevich, S. S., V. Perov and J. C. King (2002). "Near-surface turbulent fluxes in stable stratification: Calculation techniques for use in General Circulation Models." Q. J. R. Meteorol. Soc. 128(583): 1571--1587. Louis, J. F. (1979). "A Parametric Model of Vertical Eddy Fluxes in the Atmosphere." Bound.-Layer Meteor. 17(2): 187--202.

  15. Microhydrodynamics of flotation processes in the sea surface layer

    NASA Astrophysics Data System (ADS)

    Grammatika, Marianne; Zimmerman, William B.

    2001-10-01

    The uppermost surface of the ocean forms a peculiarly important ecosystem, the sea surface microlayer (SML). Comprising the top 1-1000 μm of the ocean surface, the SML concentrates many chemical substances, particularly those that are surface active. Important economically as a nursery for fish eggs and larvae, the SML unfortunately is also especially vulnerable to pollution. Contaminants that settle out from the air, have low solubility, or attach to floatable matter tend to accumulate in the SML. Bubbles contribute prominently to the dynamics of air-sea exchanges, playing an important role in geochemical cycling of material in the upper ocean and SML. In addition to the movement of bubbles, the development of a bubble cloud interrelates with the single particle dynamics of all other bubbles and particles. In the early sixties, several in situ oceanographic techniques revealed an "unbelievably immense" number of coastal bubbles of radius 15-300 μm. The spatial and temporal variation of bubble numbers were studied; acoustical oceanographers now use bubbles as tracers to determine ocean processes near the ocean surface. Sea state and rain noises have both been definitively ascribed to the radiation from huge numbers of infant micro bubbles [The Acoustic Bubble. Academic Press, San Diego]. Our research programme aims at constructing a hydrodynamic model for particle transport processes occurring at the microscale, in multi-phase flotation suspensions. Current research addresses bubble and floc microhydrodynamics as building blocks for a microscale transport model. This paper reviews sea surface transport processes in the microlayer and the lower atmosphere, and identifies those amenable to microhydrodynamic modelling and simulation. It presents preliminary simulation results including the multi-body hydrodynamic mobility functions for the modelling of "dynamic bubble filters" and floc suspensions. Hydrodynamic interactions versus spatial anisotropy and size of

  16. Thermodynamic stability of a bi-layer of copper nitride on Cu(100) surface

    NASA Astrophysics Data System (ADS)

    Pushpa, Raghani; Williamson, Izaak; Jones, Barbara

    2011-08-01

    Ultrathin insulating films composed of a few atomic layers are being extensively used for controlling the electronic coupling of nanostructures deposited on a substrate. Ultrathin film, for example, a single layer of Cu2N deposited on a Cu(100) surface (known as Cu2N/Cu(100) surface) has been used to determine the spectral properties of nanomagnets using scanning tunneling spectroscopy. However, recent experiments that measure spin relaxation times in a single atom suggest that the single layer of Cu2N does not provide efficient electronic decoupling. In this work, we study the thermodynamic stability of a bi-layer of copper nitride on the Cu(100) surface. We calculate adsorption and co-adsorption energies of Cu and N as a function of their concentration on the Cu2N/Cu(100) surface using density functional theory. We find that the adsorption and co-adsorption energies of Cu and N on the Cu2N/Cu(100) surface are of the order of a few eV. This suggests that the bi-layer of copper nitride is thermodynamically stable on the Cu(100) surface. We also find that the work function of N-adsorbed Cu2N/Cu(100) increases with the N concentration, suggesting a better insulating character of the bi-layer of copper nitride on the Cu(100) surface.

  17. Stormwater infiltration and surface runoff pollution reduction performance of permeable pavement layers.

    PubMed

    Niu, Zhi-Guang; Lv, Zhi-Wei; Zhang, Ying; Cui, Zhen-Zhen

    2016-02-01

    In this paper, the laboratory-scale permeable pavement layers, including a surface permeable brick layer, coarse sand bedding layers (thicknesses = 2, 3.5, and 5 cm), and single-graded gravel sub-base layers (thicknesses = 15, 20, 25, and 30 cm), were built to evaluate stormwater infiltration and surface runoff pollution reduction performance. And, the infiltration rate (I) and concentrations of suspended solids (SS), total phosphorus (TP), chemical oxygen demand (COD), ammonia nitrogen, and total nitrogen (TN) were measured under the simulated rainfall intensity of 72.4 mm/h over duration of 60 min. The results indicate that the thickness factor primarily influences the infiltration rate and pollutant removal rate. The highest steady infiltration rate was for surface brick layer 51.0 mm/h, for 5-cm sand bedding layer 32.3 mm/h, and for 30-cm gravel sub-base layer 42.3 mm/h, respectively. The SS average removal rate was relative higher (79.8 ∼ 98.6 %) for all layers due to the interception and filtration. The average removal rates of TP and COD were for surface layer 71.2 and 24.1 %, for 5-cm bedding layer 54.8 and 9.0 %, and for 20-cm sub-base layer 72.2 and 26.1 %. Ammonia nitrogen and TN cannot steadily be removed by layers according to the experiment results. The optimal thickness of bedding sands was 5 cm, and that of sub-base gravels was 20 ∼ 30 cm. PMID:26429141

  18. Two-Layer Variable Infiltration Capacity Land Surface Representation for General Circulation Models

    NASA Technical Reports Server (NTRS)

    Xu, L.

    1994-01-01

    A simple two-layer variable infiltration capacity (VIC-2L) land surface model suitable for incorporation in general circulation models (GCMs) is described. The model consists of a two-layer characterization of the soil within a GCM grid cell, and uses an aerodynamic representation of latent and sensible heat fluxes at the land surface. The effects of GCM spatial subgrid variability of soil moisture and a hydrologically realistic runoff mechanism are represented in the soil layers. The model was tested using long-term hydrologic and climatalogical data for Kings Creek, Kansas to estimate and validate the hydrological parameters. Surface flux data from three First International Satellite Land Surface Climatology Project Field Experiments (FIFE) intensive field compaigns in the summer and fall of 1987 in central Kansas, and from the Anglo-Brazilian Amazonian Climate Observation Study (ABRACOS) in Brazil were used to validate the mode-simulated surface energy fluxes and surface temperature.

  19. Surface Phonon Dispersion of the Layered Transition-metal Oxides

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Ismail; Matzdorf, R.; Plummer, E. W.; Kimura, T.; Tokura, Y.

    2000-03-01

    Transition-metal oxides exhibit strong coupling between the charge and spin of the electrons and the lattice. Creating a surface by cleaving a single crystal breaks the symmetry of the lattice and disturbs the correlated system without changing the stoichiometry, providing the opportunity to study the response of electronic, structural, and magnetic properties. We have utilized electron-energy loss sprectroscopy (EELS) to study the electronic and lattice excitations of the Sr_2RuO4 and La_0.5Sr_1.5MnO4 surfaces. For both of these materials there are many more than three modes; three dominate surface optical phonons with small dispersion and with higher energies compared to those in the bulk materials. However, these phonons show completely different temperature dependence for different samples. The surface phonons become soft for Sr_2RuO4 while they become stiff for La_0.5Sr_1.5MnO4 with increasing temparature. The change of phonon energy of La_0.5Sr_1.5MnO4 with temperature is also in opposite direction to that of (La, Ca)MnO_4( Zhang et al., Surf. Sci. 393, 64(1997) * LMER Corp. for U.S. DOE under contract No. DE-AC05-96OR22464). These behaviors will be discussed in terms of the electronic, magnetic, and structural properties.

  20. Microstructure and biocompatibility of titanium oxides produced on nitrided surface layer under glow discharge conditions.

    PubMed

    Czarnowska, E; Morgiel, J; Ossowski, M; Major, R; Sowinska, A; Wierzchon, T

    2011-10-01

    The disadvantages of titanium implants are their low wear resistance and the release of titanium elements into surrounding tissue. These can be eliminated by modifying the surface by surface engineering methods, among them nitriding under glow discharge conditions which allow to produce diffusive surface layers. Their combining with an oxide layer might be valuable for biological events occurring at the bone implant interface. The aim of this study was to enhance the titanium biomaterial performance via combining nitriding and oxidizing treatments in one process under glow discharge conditions. The oxynitrided surface layers were produced at 680 degrees C. The obtained layer was TiO + TiN + Ti2N + alphaTi(N) type and about 4-microm thick and was of diffusive character. This layer significantly increased wear resistance and slightly corrosion resistance compared to that of the reference titanium alloy. The produced titanium oxide was about 400-nm thick and built from fine crystallites. This oxide exhibits bioactivity in SBF (simulated body fluid). Osteoblasts of Saos-2 line incubated on this surface exhibited good adhesion and proliferation and ALP release comparable with cells cultured on the reference titanium alloy and TiN + Ti2N + alphaTi(N) surface layers. A quantitative analysis of blood platelets adhering to this layer revealed their highest amount in comparison to that on both the nitrided surface layer and titanium alloy. The presented study provided a simple and reproducible method of combining oxidizing and nitriding under glow discharge in one process. Experimental data in vitro suggests that titanium alloy oxynitriding under low temperatures at glow discharge conditions improves titanium alloy properties and biocompatibility and tissue healing. Therefore, the layer of TiO + TiN +Ti2N + alphaTi(N) type could be valuable for long-term bone implants. PMID:22400281

  1. Surface-segregated Si and Ge ultrathin films formed by Ag-induced layer exchange process

    NASA Astrophysics Data System (ADS)

    Kurosawa, Masashi; Ohta, Akio; Araidai, Masaaki; Zaima, Shigeaki

    2016-08-01

    We have developed a new method of growing Si or Ge ultrathin films on a Ag(111) surface by using a Ag-induced layer exchange (ALEX) process toward the creation of 2D honeycomb sheets of Si and Ge, known as silicene and germanene, respectively. In the present paper, we clarify ALEX features, specifically the surface segregation of Si (or Ge) atoms from the underlying substrate, focusing on the annealing temperature and time. Hard X-ray photoelectron spectroscopy analyses demonstrate that surface-segregated Si (or Ge) exists on the Ag surfaces after the epitaxial growth of the Ag layer on Si(111) [or Ge(111)] substrates; the amount of segregated Si (or Ge) can be controlled by a subsequent annealing. Also, we find that the segregation of an ultrathin Si or Ge layer proceeds at an interface between Ag and the AlO x capping layer.

  2. Rapid Melt and Resolidification of Surface Layers Using Intense, Pulsed Ion Beams Final Report

    SciTech Connect

    Renk, Timothy J. Turman, Bob Senft, Donna Sorensen, Neil R. Stinnett, Regan Greenly, John B. Thompson, Michael O. Buchheit, Rudolph G.

    1998-10-02

    The emerging technology of pulsed intense ion beams has been shown to lead to improvements in surface characteristics such as hardness and wear resistance, as well as mechanical smoothing. We report hereon the use of this technology to systematically study improvements to three types of metal alloys - aluminum, iron, and titanium. Ion beam tieatment produces a rapid melt and resolidification (RMR) of the surface layer. In the case of a predeposited thin-fihn layer, the beam mixes this layer into the substrate, Ieading to improvements that can exceed those produced by treatment of the alloy alone, In either case, RMR results in both crystal refinement and metastable state formation in the treated surface layer not accessible by conventional alloy production. Although more characterization is needed, we have begun the process of relating these microstructural changes to the surface improvements we discuss in this report.

  3. A manufacturing method for multi-layer polysilicon surface-micromachining technology

    SciTech Connect

    Sniegowski, J.J.; Rodgers, M.S.

    1998-01-01

    An advanced manufacturing technology which provides multi-layered polysilicon surface micromachining technology for advanced weapon systems is presented. Specifically, the addition of another design layer to a 4 levels process to create a 5 levels process allows consideration of fundamentally new architecture in designs for weapon advanced surety components.

  4. Surface Morphology Transformation Under High-Temperature Annealing of Ge Layers Deposited on Si(100).

    PubMed

    Shklyaev, A A; Latyshev, A V

    2016-12-01

    We study the surface morphology and chemical composition of SiGe layers after their formation under high-temperature annealing at 800-1100 °C of 30-150 nm Ge layers deposited on Si(100) at 400-500 °C. It is found that the annealing leads to the appearance of the SiGe layers of two types, i.e., porous and continuous. The continuous layers have a smoothened surface morphology and a high concentration of threading dislocations. The porous and continuous layers can coexist. Their formation conditions and the ratio between their areas on the surface depend on the thickness of deposited Ge layers, as well as on the temperature and the annealing time. The data obtained suggest that the porous SiGe layers are formed due to melting of the strained Ge layers and their solidification in the conditions of SiGe dewetting on Si. The porous and dislocation-rich SiGe layers may have properties interesting for applications. PMID:27541814

  5. 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…

  6. Formation of Hard Surfacing Layers of WC-Co with Electron Beam Cladding Method

    NASA Astrophysics Data System (ADS)

    Abe, Nobuyuki; Morimoto, Junji

    Hard surfacing layers of WC-Co/Ni-base self-fluxing alloy were successfully formed on a steel substrate using an electron beam cladding method. The WC particles were densely and homogenously dispersed within the Ni-base self-fluxing alloy without porosity. The effect of the electron beam conditions on layer formation was investigated, and the cladding layer properties were examined by hardness tests, abrasive wear tests and immersion corrosion tests. It was found that the cladding layers showed higher hardness and abrasion resistance with increasing WC-Co mixing ratio, however, corrosion resistance decreased with WC-Co mixing ratio. A coating layer having high abrasive and corrosion resistance simultaneously was achieved by multiple cladding of high WC-Co mixing ratio layers after low WC-Co mixing ratio layers.

  7. Microstructures of Si surface layers implanted with Cu

    SciTech Connect

    Follstaedt, D.M.; Myers, S.M.

    1993-12-31

    Microstructures of Si ion-implanted with Cu have been characterized by TEM after annealing. For 1.2 at.%, the Cu is trapped at planar defects, but for 10 at.%, {eta}-Cu{sub 3}Si forms and Cu diffuses at its equilibrium solubility. These observations allow proper evaluation of the binding energies of Cu to previously formed internal cavities (2.2 eV) and {eta}-Cu{sub 3}Si (1.7 eV). The 10 at.% Cu layer promotes oxidation of Si catalyzed by {eta}-Cu{sub 3}Si. The microstructures also indicate that Si implanted with {approximately}2 at.% Cu reforms epitaxially with embedded defects after 8 hr at 700C, but for {approximately}10 at.% Cu, epitaxy is not recovered after 6 hours at 600C.

  8. Surface morphology study of recrystallization dynamics of amorphous ZnO layers prepared on different substrates

    NASA Astrophysics Data System (ADS)

    Haško, Daniel; Bruncko, Jaroslav; Uherek, František

    2014-06-01

    Amorphous oxides-based devices are exposed, during fabrication, to different processing conditions affecting their properties. Zinc oxide is a prospective candidate for transparent amorphous oxides, but its structure is changing under the influence of temperature. We investigated surface recrystallization of amorphous zinc oxide layers deposited onto fused silica, sapphire and Si substrates by pulsed laser deposition. The prepared three series of layers had highly nonequilibrium phase structures. Using atomic force microscopy and scanning electron microscopy, the effect was studied of subsequent annealing at 200, 400, 600, 800 °C for 60 min upon the surface structural properties of the layers. The following parameters were analyzed: average roughness, RMS roughness and size of formed grains on selected places with 1 × 1 μm2 area. Surface structural analysis revealed that annealing led to recrystallization of the prepared layers and roughening of the structural features on the surface. With increasing annealing temperature, the calculated parameters were increasing. The average surface roughness of zinc oxide layers annealed at 800 °C is three times higher than that of the layers annealed at lower temperatures for all substrates used. The process dynamics of thermally caused recrystallization of the layers was different for each of the substrates used.

  9. A simple method to determine evaporation duct height in the sea surface boundary layer

    NASA Astrophysics Data System (ADS)

    Musson-Genon, Luc; Gauthier, Sylvie; Bruth, Eric

    1992-09-01

    A formulation to determine the evaporation duct height in the sea surface boundary layer is presented. This formulation is based upon the theory of similarity of Monin Obukhov by using analytical solutions currently used in the field of numerical weather prediction. The proposed solution is simple, coherent with the surface boundary layer parameterization used in the Meteo France and European Centre for Medium-Range Weather Forecasts weather prediction models and gives good results when compared to more traditional methods.

  10. Comparison of a carboxylated terthiophene surface with carboxymethylated dextran layer for surface plasmon resonance detection of progesterone.

    PubMed

    Wang, Yijing; Partridge, Ashton; Wu, Yinqiu

    2016-09-01

    Functionalization of a gold surface is usually accomplished by covalent binding via self-assembled monolayers (SAMs) on the gold surface, followed by attachment of flexible polymeric linker layers such as dextran hydrogels. However, these techniques require multiple steps and also have nonspecific interactions and steric problems. In this study, a self-assembled carboxylated terthiophene monolayer was formed onto a gold surface to create a sensitive and stable surface plasmon resonance (SPR) biosensing system. Compared with a commercial carboxymethyl dextran chip (CM5), the terthiophene SAM surface provided more than six times more antibody-binding signals and nearly three times the SPR assay sensitivity for progesterone (P4). PMID:27288558

  11. Near Surface Vapor Bubble Layers in Buoyant Low Stretch Burning of Polymethylmethacrylate

    NASA Technical Reports Server (NTRS)

    Olson, Sandra L.; Tien, J. S.

    1999-01-01

    Large-scale buoyant low stretch stagnation point diffusion flames over solid fuel (polymethylmethacrylate) were studied for a range of aerodynamic stretch rates of 2-12/ sec which are of the same order as spacecraft ventilation-induced stretch in a microgravity environment. An extensive layer of polymer material above the glass transition temperature is observed. Unique phenomena associated with this extensive glass layer included substantial swelling of the burning surface, in-depth bubble formation, and migration and/or elongation of the bubbles normal to the hot surface. The bubble layer acted to insulate the polymer surface by reducing the effective conductivity of the solid. The reduced in-depth conduction stabilized the flame for longer than expected from theory neglecting the bubble layer. While buoyancy acts to move the bubbles deeper into the molten polymer, thermocapillary forces and surface regression both act to bring the bubbles to the burning surface. Bubble layers may thus be very important in low gravity (low stretch) burning of materials. As bubbles reached the burning surface, monomer fuel vapors jetted from the surface, enhancing burning by entraining ambient air flow. Popping of these bubbles at the surface can expel burning droplets of the molten material, which may increase the fire propagation hazards at low stretch rates.

  12. Controlled surface functionality of magnetic nanoparticles by layer-by-layer assembled nano-films

    NASA Astrophysics Data System (ADS)

    Choi, Daheui; Son, Boram; Park, Tai Hyun; Hong, Jinkee

    2015-04-01

    Over the past several years, the preparation of functionalized nanoparticles has been aggressively pursued in order to develop desired structures, compositions, and structural order. Among the various nanoparticles, iron oxide magnetic nanoparticles (MNPs) have shown great promise because the material generated using these MNPs can be used in a variety of biomedical applications and possible bioactive functionalities. In this study, we report the development of various functionalized MNPs (F-MNPs) generated using the layer-by-layer (LbL) self-assembly method. To provide broad functional opportunities, we fabricated F-MNP bio-toolbox by using three different materials: synthetic polymers, natural polymers, and carbon materials. Each of these F-MNPs displays distinct properties, such as enhanced thickness or unique morphologies. In an effort to explore their biomedical applications, we generated basic fibroblast growth factor (bFGF)-loaded F-MNPs. The bFGF-loaded F-MNPs exhibited different release mechanisms and loading amounts, depending on the film material and composition order. Moreover, bFGF-loaded F-MNPs displayed higher biocompatibility and possessed superior proliferation properties than the bare MNPs and pure bFGF, respectively. We conclude that by simply optimizing the building materials and the nanoparticle's film composition, MNPs exhibiting various bioactive properties can be generated.Over the past several years, the preparation of functionalized nanoparticles has been aggressively pursued in order to develop desired structures, compositions, and structural order. Among the various nanoparticles, iron oxide magnetic nanoparticles (MNPs) have shown great promise because the material generated using these MNPs can be used in a variety of biomedical applications and possible bioactive functionalities. In this study, we report the development of various functionalized MNPs (F-MNPs) generated using the layer-by-layer (LbL) self-assembly method. To provide

  13. On the coupling between a supersonic boundary layer and a flexible surface

    NASA Technical Reports Server (NTRS)

    Frendi, Abdelkader; Maestrello, Lucio; Bayliss, Alvin

    1992-01-01

    The coupling between a two-dimensional, supersonic, laminar boundary layer and a flexible surface is studied using direct numerical computations of the Navier-Stokes equations coupled with the plate equation. The flexible surface is forced to vibrate by plane acoustic waves at normal incidence emanated by a sound source located on the side of the flexible surface opposite to the boundary layer. The effect of the source excitation frequency on the surface vibration and boundary layer stability is analyzed. We find that, for frequencies near the fifth natural frequency of the surface or lower, large disturbances are introduced in the boundary layer which may alter its stability characteristics. The interaction between a stable two-dimensional disturbance of Tollmien-Schlichting (TS) type with the vibrating surface is also studied. We find that the disturbance level is higher over the vibrating flexible surface than that obtained when the surface is rigid, which indicates a strong coupling between flow and structure. However, in the absence of the sound source the disturbance level over the rigid and flexible surfaces are identical. This result is due to the high frequency of the TS disturbance which does not couple with the flexible surface.

  14. Solution-processed amorphous silicon surface passivation layers

    SciTech Connect

    Mews, Mathias Sontheimer, Tobias; Korte, Lars; Rech, Bernd; Mader, Christoph; Traut, Stephan; Wunnicke, Odo

    2014-09-22

    Amorphous silicon thin films, fabricated by thermal conversion of neopentasilane, were used to passivate crystalline silicon surfaces. The conversion is investigated using X-ray and constant-final-state-yield photoelectron spectroscopy, and minority charge carrier lifetime spectroscopy. Liquid processed amorphous silicon exhibits high Urbach energies from 90 to 120 meV and 200 meV lower optical band gaps than material prepared by plasma enhanced chemical vapor deposition. Applying a hydrogen plasma treatment, a minority charge carrier lifetime of 1.37 ms at an injection level of 10{sup 15}/cm{sup 3} enabling an implied open circuit voltage of 724 mV was achieved, demonstrating excellent silicon surface passivation.

  15. A surface layer variance heat budget for ENSO

    NASA Astrophysics Data System (ADS)

    Boucharel, Julien; Timmermann, Axel; Santoso, Agus; England, Matthew H.; Jin, Fei-Fei; Balmaseda, Magdalena A.

    2015-05-01

    Characteristics of the El Niño-Southern Oscillation (ENSO), such as frequency, propagation, spatial extent, and amplitude, strongly depend on the climatological background state of the tropical Pacific. Multidecadal changes in the ocean mean state are hence likely to modulate ENSO properties. To better link background state variations with low-frequency amplitude changes of ENSO, we develop a diagnostic framework that determines locally the contributions of different physical feedback terms on the ocean surface temperature variance. Our analysis shows that multidecadal changes of ENSO variance originate from the delicate balance between the background-state-dependent positive thermocline feedback and the atmospheric damping of sea surface temperatures anomalies. The role of higher-order processes and atmospheric and oceanic nonlinearities is also discussed. The diagnostic tool developed here can be easily applied to other tropical ocean areas and climate phenomena.

  16. Airway and lung pathology due to mucosal surface dehydration in β-Epithelial Na+ Channel-overexpressing mice: role of TNFα and IL-4Rα signaling, influence of neonatal development, and limited efficacy of glucocorticoid treatment

    PubMed Central

    Livraghi, Alessandra; Grubb, Barbara R.; Hudson, Elizabeth J.; Wilkinson, Kristen J.; Sheehan, John K.; Mall, Marcus A.; O'Neal, Wanda K.; Boucher, Richard C.; Randell, Scott H.

    2009-01-01

    Overexpression of the epithelial Na+ channel β subunit (Scnn1b gene, βENaC protein) in transgenic (Tg) mouse airways dehydrates mucosal surfaces, producing mucus obstruction, inflammation, and neonatal mortality. Airway inflammation includes macrophage activation, neutrophil and eosinophil recruitment, and elevated KC, TNFα and chitinase levels. These changes recapitulate aspects of complex human obstructive airway diseases, but their molecular mechanisms are poorly understood. We used genetic and pharmacologic approaches to identify pathways relevant to the development of Scnn1b-Tg mouse lung pathology. Genetic deletion of tumor necrosis factor alpha (TNFα) or its receptor, TNFR1, had no measurable effect on the phenotype. Deletion of the interleukin-4 receptor alpha subunit (IL-4Rα) abolished transient mucous secretory cell (MuSC) abundance and eosinophilia normally observed in neonatal wild-type (WT) mice. Similarly, IL-4Rα deficiency decreased MuSC and eosinophils in neonatal Scnn1b-Tg mice, which correlated with improved neonatal survival. However, chronic lung pathology in adult Scnn1b-Tg mice was not affected by IL-4Rα status. Prednisolone treatment ablated eosinophilia and MuSC in adult Scnn1b-Tg mice, but did not decrease mucus plugging or neutrophilia. These studies demonstrate that: 1) normal neonatal mouse airway development entails an IL-4Rα-dependent, transient abundance of MuSC and eosinophils; 2) absence of IL-4Rα improved neonatal survival of Scnn1b-Tg mice, likely reflecting decreased formation of asphyxiating mucus plugs; and 3) in Scnn1b-Tg mice, neutrophilia, mucus obstruction, and airspace enlargement are IL-4Rα- and TNFα-independent, and only MuSC and eosinophilia are sensitive to glucocorticoids. Thus, manipulation of multiple pathways will likely be required to treat the complex pathogenesis caused by airway surface dehydration. PMID:19299736

  17. Methane oxidation and methane fluxes in the ocean surface layer and deep anoxic waters

    NASA Technical Reports Server (NTRS)

    Ward, B. B.; Kilpatrick, K. A.; Novelli, P. C.; Scranton, M. I.

    1987-01-01

    Measured biological oxidation rates of methane in near-surface waters of the Cariaco Basin are compared with the diffusional fluxes computed from concentration gradients of methane in the surface layer. Methane fluxes and oxidation rates were investigated in surface waters, at the oxic/anoxic interface, and in deep anoxic waters. It is shown that the surface-waters oxidation of methane is a mechanism which modulates the flux of methane from marine waters to the atmosphere.

  18. Marine Atmospheric Surface Layer and Its Application to Electromagnetic Wave Propagation

    NASA Astrophysics Data System (ADS)

    Wang, Q.

    2015-12-01

    An important application of the atmospheric surface layer research is to characterize the near surface vertical gradients in temperature and humidity in order to predict radar and radio communication conditions in the environment. In this presentation, we will give an overview of a new research initiative funded under the Office of Naval Research (ONR) Multi-University Research Initiative (MURI): the Coupled Air-Sea Processes and EM Ducting Research (CASPER). The objective is to fully characterize the marine atmospheric boundary layer (MABL) as an electromagnetic (EM) propagation environment with the emphasis of spatial and temporal heterogeneities and surface wave/swell effects, both of which contravene the underlying assumptions of Monin-Obukhov Similarity Theory (MOST) used in coupled environmental forecast models. Furthermore, coastal variability in the inversion atop the MABL presents a challenge to forecast models and also causes practical issues in EM prediction models. These issues are the target of investigation of CASPER. CASPER measurement component includes two major field campaigns: CASPER-East (2015 Duck, NC) and CASPER-West (2018 southern California). This presentation will show the extensive measurements to be made during the CASPER -East field campaign with the focus on the marine atmospheric surface layer measurements with two research vessels, two research aircraft, surface flux buoy, wave gliders, ocean gliders, tethered balloons, and rawinsondes. Unlike previous research on the marine surface layer with the focus on surface fluxes and surface flux parameterization, CASPER field campaigns also emphasize of the surface layer profiles and the validation of the surface layer flux-profile relationship originally derived over land surfaces. Results from CASPER pilot experiment and preliminary results from CASPER-East field campaign will be discussed.

  19. Synthesis of superhydrophobic SiO{sub 2} layers via combination of surface roughness and fluorination

    SciTech Connect

    Kim, Eun-Kyeong; Yeong Kim, Ji; Sub Kim, Sang

    2013-01-15

    We describe the preparation of superhydrophobic SiO{sub 2} layers through a combination of surface roughness and fluorination. Electrospraying SiO{sub 2} precursor solutions that were prepared by a sol-gel route and included trichloro(1H,1H,2H,2H-perfluorooctyl)silane as a fluorination source produced highly rough, fluorinated SiO{sub 2} layers. In sharp contrast to the fluorinated flat SiO{sub 2} layer, the fluorinated rough SiO{sub 2} layer showed much enhanced repellency toward liquid droplets of different surface tensions. The surface fraction and the work of adhesion of the superhydrophobic SiO{sub 2} layers were determined, respectively, based on Cassie-Baxter and Young-Dupre equations. The satisfactory long-term stability for 30 days, the ultraviolet resistance and the thermal stability up to 400 {sup o}C of the superhydrophobic SiO{sub 2} layers prepared in this work confirm a promising practical application. - Graphical abstract: A schematic illustration of the electrospray deposition used for preparing SiO{sub 2} layers. Shapes of liquid droplets of water, glycerol, coffee, juice and milk created on the fluorinated rough SiO{sub 2} layer deposited on a silicon wafer. Highlights: Black-Right-Pointing-Pointer Superhydrophobic SiO{sub 2} layers are realized by a combination of surface roughness and fluorination. Black-Right-Pointing-Pointer The fluorinated rough SiO{sub 2} layer shows enhanced repellency toward various liquid droplets. Black-Right-Pointing-Pointer The wetting behavior is explained based on Cassie-Baxter and Young-Dupre equations. Black-Right-Pointing-Pointer The superhydrophobic SiO{sub 2} layers confirm a promising practical application.

  20. Long-term cultures of polarized airway epithelial cells from patients with cystic fibrosis.

    PubMed

    Wiszniewski, Ludovic; Jornot, Lan; Dudez, Tecla; Pagano, Alessandra; Rochat, Thierry; Lacroix, Jean Silvain; Suter, Susanne; Chanson, Marc

    2006-01-01

    The poor ability of respiratory epithelial cells to proliferate and differentiate in vitro into a pseudostratified mucociliated epithelium limits the general use of primary airway epithelial cell (AEC) cultures generated from patients with rare diseases, such as cystic fibrosis (CF). Here, we describe a procedure to amplify AEC isolated from nasal polyps and generate long-term cultures of the respiratory epithelium. AEC were seeded onto microporous permeable supports that carried on their undersurface a preformed feeder layer of primary human airway fibroblasts. The use of fibroblast feeder layers strongly stimulated the proliferation of epithelial cells, allowing the expansion of the cell pool with successive passages. AEC at increasing passage were seeded onto supports undercoated with airway fibroblasts and exposed to air. Either freshly isolated or amplified AEC could differentiate into a pseudostratified mucociliated epithelium for at least 10 mo. Thus, CF epithelia cultures showed elevated Na+ transport, drastic hyperabsorption of surface liquid, and absence of cAMP-induced Cl- secretion as compared with non-CF cultures. They were also characterized by thick apical secretion that hampered the movement of cell surface debris by cilia. However, CF respiratory epithelia did not show increased production of mucins or IL-8. The method described here is now routinely used in our laboratory to establish long-term cultures of well differentiated respiratory epithelia from human airway biopsies. PMID:16179582

  1. Cloud layer thicknesses from a combination of surface and upper-air observations

    NASA Technical Reports Server (NTRS)

    Poore, Kirk D.; Wang, Junhong; Rossow, William B.

    1995-01-01

    Cloud layer thicknesses are derived from base and top altitudes by combining 14 years (1975-1988) of surface and upper-air observations at 63 sites in the Northern Hemisphere. Rawinsonde observations are employed to determine the locations of cloud-layer top and base by testing for dewpoint temperature depressions below some threshold value. Surface observations serve as quality checks on the rawinsonde-determined cloud properties and provide cloud amount and cloud-type information. The dataset provides layer-cloud amount, cloud type, high, middle, or low height classes, cloud-top heights, base heights and layer thicknesses, covering a range of latitudes from 0 deg to 80 deg N. All data comes from land sites: 34 are located in continental interiors, 14 are near coasts, and 15 are on islands. The uncertainties in the derived cloud properties are discussed. For clouds classified by low-, mid-, and high-top altitudes, there are strong latitudinal and seasonal variations in the layer thickness only for high clouds. High-cloud layer thickness increases with latitude and exhibits different seasonal variations in different latitude zones: in summer, high-cloud layer thickness is a maximum in the Tropics but a minimum at high latitudes. For clouds classified into three types by base altitude or into six standard morphological types, latitudinal and seasonal variations in layer thickness are very small. The thickness of the clear surface layer decreases with latitude and reaches a summer minimum in the Tropics and summer maximum at higher latitudes over land, but does not vary much over the ocean. Tropical clouds occur in three base-altitude groups and the layer thickness of each group increases linearly with top altitude. Extratropical clouds exhibit two groups, one with layer thickness proportional to their cloud-top altitude and one with small (less than or equal to 1000 m) layer thickness independent of cloud-top altitude.

  2. XPS study on double glow plasma corrosion-resisting surface alloying layer

    NASA Astrophysics Data System (ADS)

    Ai, Jiahe; Xu, Jiang; He, Fei; Xie, Xishan; Xu, Zhong

    2003-02-01

    Double glow plasma corrosion-resisting surface alloying layer (SAL) formed on low carbon steel 1020 was studied by X-ray photoelectron spectroscopy (XPS) and other means. Results show that the passive film of the surface alloying layer after electrochemical test in 3.5% NaCl solution consists of Cr and Fe oxide such as CrO 3, Cr 2O 3, Fe 2O 3 and FeO and metallic Ni and Mo, and it attributes to the fact that a continuous and compact corrosion-resisting surface alloying layer with rich Cr, Ni and Mo was formed on the surface of steel 1020 so as to increase its corrosion resistance greatly. Therefore, double glow plasma technique will be widely used in corrosion-resisting surface science.

  3. Interfacial layer effects on surface capacitances and electro-osmosis in electrolytes.

    PubMed

    Bonthuis, Douwe Jan; Uematsu, Yuki; Netz, Roland R

    2016-02-13

    Many properties of the interfacial layer of water at surfaces differ significantly from those of bulk water. The consequences are most significant for the double-layer capacitance and the electrokinetic properties. We model the interfacial hydration layer by a modified dielectric constant and a modified local viscosity over a single interfacial width. Analytic expressions in the low-charge Debye-Hückel approximation are derived and shown to describe experimental surface capacitance and electro-osmotic data in a unified framework. PMID:26712645

  4. Polyethylenimine surface layer for enhanced virus immobilization on cellulose

    NASA Astrophysics Data System (ADS)

    Tiliket, Ghania; Ladam, Guy; Nguyen, Quang Trong; Lebrun, Laurent

    2016-05-01

    Thin regenerated cellulose films are prepared by hydrolysis of cellulose acetate (CA). A polycation, namely polyethylenimine (PEI), is then adsorbed onto the films. From QCM-D analysis, PEI readily adsorbs from a 0.1% w/v solution in NaCl 0.2 M (ca. 100 ng cm-2). Further PEI adsorption steps at higher PEI concentrations induce a linear growth of the PEI films, suggesting that free adsorption sites still exist after the initial adsorption. The adsorbed PEI chains are resistant to variations of the ionic strength up to NaCl 1 M. Promisingly, the adsorption of T4D bacteriophages are 15-fold more efficient onto the PEI-treated, compared to the native regenerated cellulose films, as measured by QCM-D. This confirms the strong affinity between the negatively charged viruses and PEI, even at low PEI concentration, probably governed by strong electrostatic attractive interactions. This result explains the remarkable improvement of the affinity of medical masks for virus droplets when one of their cellulose layers was changed by two-PEI-functionalized cellulose-based filters.

  5. Influence of transverse surface waves on turbulent boundary layers

    NASA Technical Reports Server (NTRS)

    Balasubramanian, R.; Ash, R. L.; Cary, A. M., Jr.; Bushnell, D. M.

    1977-01-01

    Wavy wall experiments using solid waves and progressive waves have been reported. For this paper, the major effects of waviness of the wall on the flow are identified as due to oscillatory curvature (convex-concavity) and oscillatory acceleration/deceleration of the flow, which imposes a highly nonequilibrium influence upon the turbulence structure. The theoretical analysis in this presentation takes into account proper turbulence modeling (including the nonequilibrium effects) for the wavy wall problem. The analysis proceeds in three stages: (1) inviscid solution for induced pressure due to the physical wall, (2) solution of a turbulent boundary layer with pressure gradients and curvature effects in the modeling from which the profile correction is computed, and (3) induced pressure computations for the corrected profile. The phase shift of pressure perturbations with respect to the physical wall can be predicted, and pressure drag and skin friction drag can be estimated, with nonlinear viscous effects included. Comparison of the theoretical estimates with experimental data are also presented.

  6. Thermal stresses in small meteoroids. II. Effects of an insulating surface layer

    NASA Astrophysics Data System (ADS)

    Čapek, D.; Vokrouhlický, D.

    2012-03-01

    Aims: We extend our previous analysis of thermal stresses in small, spherical and homogeneous meteoroids by taking into account the effects of a surface insulating layer. Methods: Using analytical computations, we determine the temperature distribution in a spherical inhomogeneous body smaller than ~10 cm with a high-conductivity core and a low-conductivity surface layer. Our main approximation consists in (i) linearization of the surface energy-conservation constraint and (ii) omission of the seasonal effects in the Fourier spectrum of the incident solar radiation flux. Using the temperature solution, we analytically compute the mechanical (thermal) stress field in the core, neglecting its effects in the particulate surface layer. Conditions for material failure in the whole volume of the body are analyzed. In particular, we pay attention to whether the surface layer depth evolves toward an equilibrium situation. Results: As the meteoroid approaches the Sun, the thermal stress first exceeds the material strength at the surface of meteoroid. If the fractured material is able to stay on meteoroid, a particulate shell begins to form. After one revolution about the Sun, this process is roughly completed. We determine the dependence of its thickness on perihelion distance, spin axis orientation with respect to the Sun, and the size of meteoroid. We estimate the distribution of the final depths of the surface layer for eight major meteoroid showers with perihelion distances smaller than 1 AU.

  7. Trapping and depth profile of tritium in surface layers of metallic materials

    NASA Astrophysics Data System (ADS)

    Matsuyama, M.; Chen, Z.; Nisimura, K.; Akamaru, S.; Torikai, Y.; Hatano, Y.; Ashikawa, N.; Oya, Y.; Okuno, K.; Hino, T.

    2011-10-01

    Tritium amount retained in surface layers and release behavior from surface layers were examined using SS316L samples exposed to plasmas in the Large Helical Device and a commercial Cu-Be alloy plate. BIXS analyses and observation by SEM indicate that carbon and titanium deposited on the plasma-facing surface of the SS316L samples. Larger amount of tritium was trapped in the plasma-facing surface in comparison with the polished surface. Higher enrichment of tritium in surface layers was similarly found in the polished surface of both samples. The amount of surface tritium in both samples was almost same, while the bulk concentration of tritium in Cu-Be was much lower than that in SS316L. Tritium release from the SS316L and Cu-Be samples into water was examined by immersion experiments. Tritium elution was observed for both samples, but changes in the residual tritium amount in surface layers were different from each other.

  8. 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

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

    PubMed

    Shah, Viral S; Meyerholz, David K; Tang, Xiao Xiao; Reznikov, Leah; Abou Alaiwa, Mahmoud; 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

    2016-01-29

    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

  10. Effect of tethering on the surface dynamics of a thin polymer melt layer.

    PubMed

    Uğur, Gökçe; Akgun, Bulent; Jiang, Zhang; Narayanan, Suresh; Satija, Sushil; Foster, Mark D

    2016-06-28

    The surface height fluctuations of a layer of low molecular weight (2.2k) untethered perdeuterated polystyrene (dPS) chains adjacent to a densely grafted polystyrene brush are slowed dramatically. Due to the interpenetration of the brush with the layer of "untethered chains" a hydrodynamic continuum theory can only describe the fluctuations when the effective thickness of the film is taken to be that which remains above the swollen brush. The portion of the film of initially untethered chains that interpenetrates with the brush becomes so viscous as to effectively play the role of a rigid substrate. Since these hybrid samples containing a covalently tethered layer at the bottom do not readily dewet, and are more robust than thin layers of untethered short chains on rigid substrates, they provide a route for tailoring polymer layer surface properties such as wetting, adhesion and friction. PMID:27222250

  11. Surface passivation of InP solar cells with InAlAs layers

    NASA Technical Reports Server (NTRS)

    Jain, Raj K.; Flood, Dennis J.; Landis, Geoffrey A.

    1993-01-01

    The efficiency of indium phosphide solar cells is limited by high values of surface recombination. The effect of a lattice-matched In(0.52)Al(0.48)As window layer material for InP solar cells, using the numerical code PC-1D is investigated. It was found that the use of InAlAs layer significantly enhances the p(+)n cell efficiency, while no appreciable improvement is seen for n(+)p cells. The conduction band energy discontinuity at the heterojunction helps in improving the surface recombination. An optimally designed InP cell efficiency improves from 15.4 percent to 23 percent AMO for a 10 nm thick InAlAs layer. The efficiency improvement reduces with increase in InAlAs layer thickness, due to light absorption in the window layer.

  12. Air-sea boundary layer dynamics in the presence of mesoscale surface currents

    NASA Astrophysics Data System (ADS)

    Rooth, Claes; Xie, Lian

    1992-09-01

    In the presence of surface currents, a shear stress at the air-sea interface is induced by the surface currents. In the case of a unidirectional current, a quadratic stress law leads to a stress curl proportional to and opposing the surface current vorticity even with a uniform wind. This causes a spindown effect on the surface vorticity field at a rate proportional to the wind speed. In the steady state, or in slowly varying processes which can be treated as parametrically developing quasi-steady states, the surface-layer potential vorticity modulation causes upwelling and downwelling patterns associated with the surface-current vorticity. These effects are analyzed for an idealized jet current, and for a physical situation characteristic of a Gulf Stream boundary ring along the Florida Keys, where the induced transport patterns may be important for onshore transport of fish and spiny lobster larvae, as well as for onshore transport to the Florida Keys of general flotsam transported past them by the Gulf Stream. The spindown time scale (t*) for a 1.5-layer system is H/( ρ'cdVa) for a surface jet on the deformation radius scale (where H is the thickness of the surface layer, Va the surface wind speed, ρ' the air to water density ratio and cd the surface drag coefficient) and increases for large horizontal scales in proportion to the current width squared. For a typical wind speed of 5 m/s and a density normalized drag coefficient ρ'cd= 2 × 10-6, t* is on the order of 1 month for a 30-m surface layer. In the more general case of a stratified interior water column, the vorticity spindown directly affects only the potential vorticity of the surface layer and generally leads to subsurface velocity and vorticity maxima for mesoscale eddies and jets.

  13. The Physiologically Difficult Airway.

    PubMed

    Mosier, Jarrod M; Joshi, Raj; Hypes, Cameron; Pacheco, Garrett; Valenzuela, Terence; Sakles, John C

    2015-12-01

    Airway management in critically ill patients involves the identification and management of the potentially difficult airway in order to avoid untoward complications. This focus on difficult airway management has traditionally referred to identifying anatomic characteristics of the patient that make either visualizing the glottic opening or placement of the tracheal tube through the vocal cords difficult. This paper will describe the physiologically difficult airway, in which physiologic derangements of the patient increase the risk of cardiovascular collapse from airway management. The four physiologically difficult airways described include hypoxemia, hypotension, severe metabolic acidosis, and right ventricular failure. The emergency physician should account for these physiologic derangements with airway management in critically ill patients regardless of the predicted anatomic difficulty of the intubation. PMID:26759664

  14. The Physiologically Difficult Airway

    PubMed Central

    Mosier, Jarrod M.; Joshi, Raj; Hypes, Cameron; Pacheco, Garrett; Valenzuela, Terence; Sakles, John C.

    2015-01-01

    Airway management in critically ill patients involves the identification and management of the potentially difficult airway in order to avoid untoward complications. This focus on difficult airway management has traditionally referred to identifying anatomic characteristics of the patient that make either visualizing the glottic opening or placement of the tracheal tube through the vocal cords difficult. This paper will describe the physiologically difficult airway, in which physiologic derangements of the patient increase the risk of cardiovascular collapse from airway management. The four physiologically difficult airways described include hypoxemia, hypotension, severe metabolic acidosis, and right ventricular failure. The emergency physician should account for these physiologic derangements with airway management in critically ill patients regardless of the predicted anatomic difficulty of the intubation. PMID:26759664

  15. Effect of Thickness on Surface Morphology of Silver Nanoparticle Layer During Furnace Sintering

    NASA Astrophysics Data System (ADS)

    Moon, Yoon Jae; Kang, Heuiseok; Kang, Kyungtae; Moon, Seung-Jae; Young hwang, Jun

    2015-04-01

    In printed electronics applications, specific resistances of conductive lines are critical to the performance of the devices. The specific resistance of a silver (Ag) nanoparticle electrode is affected by surface morphology of the layered nanoparticles which were sintered by the heat treatment after printing. In this work, the relationship between surface morphology and specific resistance was investigated with various sintering temperatures and various layer thicknesses of Ag nanoparticle ink. Ag nanoparticles with an average size of approximately 50 nm were spin-coated on Eagle XG glass substrates with various spin speed to change the layer thickness of Ag nanoparticles from 200 nm to 900 nm. Coated Ag nanoparticle layers were heated from 150°C to 450°C for 30 min in a furnace. The result showed that higher sintering temperature produces larger grains in an Ag layer and decreases specific resistance of the layer, but that the maximum allowable heating temperature is limited by the thickness of the layer. When grain size exceeded the thickness of the layer, the morphology of the Ag nanoparticles changed to submicron-sized islands and the Ag layers did not have electrical conductivity any more.

  16. Contribution of material's surface layer on charge state distribution in laser ablation plasma.

    PubMed

    Kumaki, Masafumi; Steski, Dannie; Ikeda, Shunsuke; Kanesue, Takeshi; Okamura, Masahiro; Washio, Masakazu

    2016-02-01

    To generate laser ablation plasma, a pulse laser is focused onto a solid target making a crater on the surface. However, not all the evaporated material is efficiently converted to hot plasma. Some portion of the evaporated material could be turned to low temperature plasma or just vapor. To investigate the mechanism, we prepared an aluminum target coated by thin carbon layers. Then, we measured the ablation plasma properties with different carbon thicknesses on the aluminum plate. The results showed that C(6+) ions were generated only from the surface layer. The deep layers (over 250 nm from the surface) did not provide high charge state ions. On the other hand, low charge state ions were mainly produced by the deeper layers of the target. Atoms deeper than 1000 nm did not contribute to the ablation plasma formation. PMID:26931982

  17. Effect of a 3D surface depression on boundary layer transition

    NASA Astrophysics Data System (ADS)

    Xu, Hui; Mughal, Shahid; Sherwin, Spencer J.

    2015-11-01

    The influence of a three-dimensional surface depression on the transitional boundary layer is investigated numerically. In the boundary layer transition, the primary mode is a Tollmien-Schlichting (TS) wave which is a viscous instability. These modes are receptive to surface roughness interacting with free stream disturbances and/or surface vibrations. In this paper, numerical calculations are carried out to investigate the effect of the depression on instability of the boundary layer. In order to implement linear analysis, two/three (2D/3D)-dimensional nonlinear Navier-Stokes equations are solved by spectral element method to generate base flows in a sufficient large domain. The linear analyses are done by the parabolic stability equations (PSE). Finally, a DNS calculation is done to simulate the boundary layer transition.

  18. Critical CuI buffer layer surface density for organic molecular crystal orientation change

    SciTech Connect

    Ahn, Kwangseok; Kim, Jong Beom; Lee, Dong Ryeol; Kim, Hyo Jung; Lee, Hyun Hwi

    2015-01-21

    We have determined the critical surface density of the CuI buffer layer inserted to change the preferred orientation of copper phthalocyanine (CuPc) crystals grown on the buffer layer. X-ray reflectivity measurements were performed to obtain the density profiles of the buffer layers and out-of-plane and 2D grazing-incidence X-ray diffraction measurements were performed to determine the preferred orientations of the molecular crystals. Remarkably, it was found that the preferred orientation of the CuPc film is completely changed from edge-on (1 0 0) to face-on (1 1 −2) by a CuI buffer layer with a very low surface density, so low that a large proportion of the substrate surface is bare.

  19. Measurement and correlation of aerodynamic heating to surface corrugation stiffened structures in thick turbulent boundary layers

    NASA Technical Reports Server (NTRS)

    Brandon, H. J.; Masek, R. V.

    1974-01-01

    The flow conditions for which heating distributions were measured on corrugated surfaces and wavy walls in turbulent boundary layers are shown, along with the ratio of the displacement thickness to the roughness height versus the local edge Mach number for an equivalent smooth surface. The present data are seen to greatly extend the range of data available on corrugated surfaces in turbulent boundary layers. These data were obtained by testing fullscale corrugation roughened panels in the wall boundary layer of a supersonic and hypersonic wind tunnel. The experimental program used to obtain the data is described. The data are analyzed and correlated in terms of the pertinent flow and geometric parameters. The developed correlations are compared with the available thin boundary layer data, as well as with previously published correlation techniques.

  20. Surface treatment for the atomic layer deposition of HfO{sub 2} on silicon

    SciTech Connect

    Damlencourt, J-F.; Renault, O.; Martin, F.; Semeria, M-N.; Billon, T; Bedu, F.

    2005-04-04

    The atomic layer deposition (ALD) of HfO{sub 2} on silicon with a Cl{sub 2} surface treatment is investigated by physicochemical and electrical techniques. The specificity of this treatment is to create, on a HF-dipped silicon surface, the nucleation sites necessary for the ALD growth. The growth rates obtained by spectroscopic ellipsometry and total x-ray fluorescence spectroscopy indicate that the nucleation sites (i.e., the -OH groups), which are necessary to perform some bidimensional ALD growth, are generated during this surface treatment. After deposition of thin HfO{sub 2} layers (from a few monolayers up to 8.7 nm), a very thin parasitic SiO{sub x} layer, underneath 1 monolayer of Hf silicate, is observed by x-ray photoelectron spectroscopy. Nevertheless, an equivalent oxide thickness of 1.1 nm is obtained with an as-deposited 3.7 nm thick HfO{sub 2} layer.

  1. An analytical study of the effects of surface roughness on a compressible turbulent boundary layer

    NASA Astrophysics Data System (ADS)

    Khan, Z. H.

    1983-12-01

    A previous study on the effect of surface roughness on the turbulent boundary layer, using a FORTRAN code, ITRACT, solved for the characteristics of a laminar, transitional and turbulent boundary layer on smooth surfaces. The present study investigates the influence of surface roughness on a compressible turbulent boundary layer and then extends the usefulness of ITRACT by including in it the optional capability of rough-surface boundary-layer calculations. Surface roughness was represented by distributed sources and sinks in the appropriate governing equations. The most important term is a sink term in the mean momentum equation, representing the form drag due to the roughness element. Governing boundary-layer equations for continuity, momentum, and energy were derived in a form to account for blockage effects due to roughness elements. The modified governing equations were then transformed using Probstein-Elliott and Levy-Lees transformations. The resulting equations, with appropriate boundary conditions, were solved by finite-difference techniques to determine the nondimensional velocity components and temperature at a finite number of nodes in the boundary-layer flow field.

  2. Enhanced magneto-optical imaging of internal stresses in the removed surface layer

    NASA Astrophysics Data System (ADS)

    Agalidi, Yuriy; Kozhukhar, Pavlo; Levyi, Sergii; Turbin, Dmitriy

    2015-10-01

    The paper describes a software method of reconstructing the state of the removed surface layer by visualising internal stresses in the underlying layers of the sample. Such a problem typically needs to be solved as part of forensic investigation that aims to reveal original marking of a sample with removed surface layer. For example, one may be interested in serial numbers of weapons or vehicles that had the surface layer of metal removed from the number plate. Experimental results of studying gradient internal stress fields in ferromagnetic sample using the NDI method of magneto-optical imaging (MOI) are presented. Numerical modelling results of internal stresses enclosed in the surface marking region are analysed and compared to the experimental results of magneto-optical imaging (MOI). MOI correction algorithm intended for reconstructing internal stress fields in the removed surface layer by extracting stresses retained by the underlying layers is described. Limiting ratios between parameters of a marking font are defined for the considered correction algorithm. Enhanced recognition properties for hidden stresses left by marking symbols are experimentally verified and confirmed.

  3. CHARACTERIZING SURFACE LAYERS IN NITINOL USING X-RAY PHOTOELECTRON SPECTROSCOPY

    SciTech Connect

    Christopfel, R.; Mehta, A.

    2008-01-01

    Nitinol is a shape memory alloy whose properties allow for large reversible deformations and a return to its original geometry. This nickel-titanium (NiTi) alloy has become a material used widely in the biomedical fi eld as a stent to open up collapsed arteries. Both ambient and biological conditions cause surface oxidation in these devices which in turn change its biocompatibility. The thickness of oxidized layers can cause fractures in the material if too large and can allow for penetration if too thin. Depending on the type and abundance of the chemical species on or near the surface, highly toxic metal ions can leak into the body causing cell damage or even cell death. Thus, biocompatibility of such devices is crucial. By using highly surface sensitive x-ray photoelectron spectroscopy to probe the surface of these structures, it is possible to decipher both layer composition and layer thickness. Two samples, both of which were mechanically polished, were investigated. Of the two samples, one was then exposed to a phosphate buffered saline (PBS) solution to mimic the chemical properties of blood, while the other remained unexposed. Although both samples were found to have oxide layers of appropriate thickness (on the order of a few nm), it was found that the sample exposed to the saline solution had a slightly thicker oxide layer and more signifi cantly, a phosphate layer very near the surface suggesting toxic metal components are well contained within the sample. These are considerable indications of a biocompatible device.

  4. Histochemistry of the surface mucous gel layer of the human colon.

    PubMed Central

    Matsuo, K; Ota, H; Akamatsu, T; Sugiyama, A; Katsuyama, T

    1997-01-01

    BACKGROUND AND AIMS: Histochemical analysis of the surface mucous gel layer of the human colon is difficult, as it dissolves in fixatives. This study was undertaken to explore the surface mucous gel layer on the normal mucosa and neoplastic tissues of the large intestine. In addition, the distribution of different mucins secreted from goblet cells was studied with a series of histochemical stains for mucins. METHODS: Twenty four surgically resected specimens were fixed in Carnoy's solution and embedded in paraffin. In four cases, the surface mucous gel layer was also studied in frozen sections. Serial sections were stained by a battery of histochemical techniques characterising mucins. RESULTS AND CONCLUSION: The surface mucous gel layer consisted of the inner and outer layers. The first covered the luminal surface of the mucosa, consisted of mucins, and showed a vertical striped pattern. The second overlaid the first, showed a lateral striped pattern, and was contaminated with bacteria and other substances. Their thickness in paraffin sections varied considerably among the sites in the large intestine, but was the thickest in the rectum and measured 12.7 (SEM 6.0) microns and 88.8 (SEM 80.1) microns respectively. Mucins forming the inner layer were obviously derived from goblet cells underlying it. Images PMID:9245933

  5. ENaC inhibitors and airway re-hydration in cystic fibrosis: state of the art.

    PubMed

    Althaus, Mike

    2013-03-01

    Cystic fibrosis (CF) is a hereditary disease caused by mutations in the gene encoding the chloride channel "cystic fibrosis transmembrane conductance regulator" (CFTR). The lack of functional CFTR in CF airways leads to impaired ion and fluid homeostasis of the fluid layer which lines the airway surfaces (ASL). The ASL is important for proper ciliary beat and clearance of mucus from the airways. According to the "low volume hypothesis", CF airway epithelia hyperabsorb sodium via the epithelial sodium channel (ENaC). Although the contribution of ENaC to CF pathogenesis is still under debate, there is convincing data demonstrating that re-hydration of the ASL might improve mucociliary clearance in CF patients. ASL re-hydration might, amongst other things, be achieved by a block of airway transepithelial sodium absorption with inhibitors of ENaC. This mini-review article describes the role of ENaC in ASL fluid homeostasis and rehydration, and summarizes the current state of the art in the discovery and establishment of compounds which inhibit ENaC activity and may represent pharmacological tools for the treatment of CF. PMID:23547930

  6. Turbulent Structures and Coherence in the Atmospheric Surface Layer

    NASA Astrophysics Data System (ADS)

    Träumner, K.; Damian, Th.; Stawiarski, Ch.; Wieser, A.

    2015-01-01

    Organized structures in turbulent flow fields are a well-known and still fascinating phenomenon. Although these so-called coherent structures are obvious from visual inspection, quantitative assessment is a challenge and many aspects e.g., formation mechanisms and contribution to turbulent fluxes, are discussed controversially. During the "High Definition Clouds and Precipitation for Advancing Climate Prediction" Observational Prototype Experiment (HOPE) from April to May 2013, an advanced dual Doppler lidar technique was used to image the horizontal wind field near the surface for approximately 300 h. A visual inspection method, as well as a two-dimensional integral length scale analysis, were performed to characterize the observations qualitatively and quantitatively. During situations with forcing due to shear, the wind fields showed characteristic patterns in the form of clearly bordered, elongated areas of enhanced or reduced wind speed, which can be associated with near-surface streaks. During calm situations with strong buoyancy forcing, open cell patterns in the horizontal divergence field were observed. The measurement technique used enables the calculation of integral length scales of both horizontal wind components in the streamwise and cross-stream directions. The individual length scales varied considerably during the observation period but were on average shorter during situations with compared to strongly stable situations. During unstable situations, which were dominated by wind fields with structures, the streamwise length scales increased with increasing wind speed, whereas the cross-stream length scales decreased. Consequently, the anisotropy increased from 1 for calm situations to values of 2-3 for wind speeds of 8-10. During neutral to stable situations, the eddies were on average quite isotropic in the horizontal plane.

  7. Measuring air layer volumes retained by submerged floating-ferns Salvinia and biomimetic superhydrophobic surfaces.

    PubMed

    Mayser, Matthias J; Bohn, Holger F; Reker, Meike; Barthlott, Wilhelm

    2014-01-01

    Some plants and animals feature superhydrophobic surfaces capable of retaining a layer of air when submerged under water. Long-term air retaining surfaces (Salvinia-effect) are of high interest for biomimetic applications like drag reduction in ship coatings of up to 30%. Here we present a novel method for measuring air volumes and air loss under water. We recorded the buoyancy force of the air layer on leaf surfaces of four different Salvinia species and on one biomimetic surface using a highly sensitive custom made strain gauge force transducer setup. The volume of air held by a surface was quantified by comparing the buoyancy force of the specimen with and then without an air layer. Air volumes retained by the Salvinia-surfaces ranged between 0.15 and 1 L/m(2) depending on differences in surface architecture. We verified the precision of the method by comparing the measured air volumes with theoretical volume calculations and could find a good agreement between both values. In this context we present techniques to calculate air volumes on surfaces with complex microstructures. The introduced method also allows to measure decrease or increase of air layers with high accuracy in real-time to understand dynamic processes. PMID:24991518

  8. Research into preparation and properties of graded cemented carbides with face center cubic-rich surface layer

    NASA Astrophysics Data System (ADS)

    Chen, Jian; Deng, Xin; Gong, Manfeng; Liu, Wei; Wu, Shanghua

    2016-09-01

    This paper systematically investigated a set of functionally graded WC-TiC-Mo-Co cemented carbides with modified surface layer (called fcc-rich surface layer in this study), which is mainly composed of fcc phases (Ti(CN) and TiN) and WC. Nitridation at liquid phase sintering temperature is the key process making this fcc-rich surface layer. The functionally graded WC-TiC-Mo-Co cemented carbides synthesized in this study show 3 layer structure: the outer layer, i.e. the fcc-rich surface layer; the intermediate layer, which is characterized by abnormally large WC and high Co content; and the inner layer. It was found that TiC is the most critical component for the formation of fcc-rich surface layer. The higher content of TiC results in the thicker fcc-rich outer layer, higher (Ti(CN) and TiN) content in the outer layer, and higher hardness of the fcc-rich outer layer. The formation of this fcc-rich surface layer is mainly due to the nitridation process between Ti and N, which leads to the diffusion of Ti outwards (from the inside of the sample to the surface) and the subsequent migration of liquid cobalt inwards (from surface to the inside of the sample). The three-layer structure developed in this study provides the excellent combination of high wear resistance and high toughness, which is favorable for some applications.

  9. Experimental Study on Surface Characteristics of Laser Cladding Layer Regulated by High-Frequency Microforging

    NASA Astrophysics Data System (ADS)

    Fan, Xiang Fang; Zhou, Ju; Qiu, Chang Jun; He, Bin; Ye, Jiang; Yuan, Bo; Pi, Zhengqing

    2011-03-01

    High-frequency microforging technology is used to produce micrometer-scale plastic deformation on the surface of material out of the vibration impact of a forging punch, and the cumulative effect of its various frequencies on micrometer-scale plastic deformation can cause changes of surface microstructure and mechanical properties. This study used (1) a self-made machine to treat NiCrBSi alloy, (2) a mechanical comparator and optical microscopy (OM) to study the geometric characteristics of plastic deformation, (3) OM and scanning electric microscopy (SEM) to observe influence on surface microstructure and cracking behavior of the laser cladding layer under microforging, (4) x-ray diffractometer (XRD) to measure the surface residual stress of laser cladding layer before and after forging, and (5) microhardness tester and wearing experimental machine to study changes of microhardness, friction coefficient, and wear characteristics of laser cladding layer after microforging. The results have shown that high-frequency microforging could produce plastic deformation about 150 μm deep on the surface of NiCrBSi alloy clad by laser. Regular dendrite and eutectic crystallization microstructure, which is a peculiar characteristic of the laser cladding layer, was broken into pieces and formed residual compression residual stress on the surface. Resistance to cracking of laser cladding layer improved greatly, microhardness and wearability increased, and the friction coefficient did not under go a noticeable change.

  10. Surface layer composition of titania produced by various methods. The change of layer state under illumination

    NASA Astrophysics Data System (ADS)

    Zakharenko, V.; Daibova, E.; Kosova, N.; Zmeeva, O.

    2016-01-01

    The comparative analysis of experimental data over titanium dioxide powders prepared by various ways under ambient air is carried out. The results over TiO2 prepared by high-temperature heating of anatase, produced by burning of titanium micro particles and grinding of rutile crystal are used for that comparison. Water and carbon dioxide were the main products released from the surface of the titania powders. It was found that under UV irradiation absorbed by titania, in absent oxygen, water effectively reacts with lattice oxygen of titanium dioxide.

  11. Improvement of the surface wettability of silicone hydrogel contact lenses via layer-by-layer self-assembly technique.

    PubMed

    Lin, Chien-Hong; Cho, Hsien-Lung; Yeh, Yi-Hsing; Yang, Ming-Chien

    2015-12-01

    The surface wettability and anti-protein adsorption of a silicone-based hydrogel that was synthesized by a block copolymer of polydimethylsiloxane (PDMS) and poly (ethylene glycol) methacrylate (PEGMA) was improved via polyelectrolyte multilayer (PEM) immobilization. Polysaccharide PEMs of chitosan (CS, as a positive-charged agent) and hyaluronic acid (HA, as a negative-charged and anti-adhesive agent) were successfully assembled on the PDMS-PU-PEGMA silicone hydrogel in a layer-by-layer (LBL) self-assembly manner. Atomic force microscopy (AFM) and dyeing data verified the progressive buildup of the PEM silicone hydrogel. The results showed that the contact angle of the silicone hydrogel decreased with an increase in the number of PEM grafting layers. Furthermore, after immobilizing five layers of CS/HA, the protein adsorption decreased from 78 ± 11 to 26 ± 4 μg/cm(2) for HSA and from 55 ± 10 to 20 ± 4 μg/cm(2) for lysozymes. This indicates that CS/HA PEM-immobilized silicone hydrogels can resist protein adsorption. Furthermore, these hydrogels were non-cytotoxic according to an in vitro L929 fibroblast assay. Overall, the results demonstrated that the modified silicone hydrogels exhibited hydrophilicity and anti-protein adsorption, as well as relatively high oxygen permeability and optical transparency. Therefore, they would be applicable as a contact lens material. PMID:26519935

  12. Radar scattering from a diffuse vegetation layer over a smooth surface

    NASA Technical Reports Server (NTRS)

    Engheta, N.; Elachi, C.

    1982-01-01

    A simple model is presented for the oblique backscatter and bistatic scatter from a smooth surface overlain by a diffuse layer. Only single scattering in the diffuse layer is taken into account. The model analysis shows that the combination of volume scattering and oblique reflection at the surface may increase appreciably the waves scattering. The scattering strongly depends on the properties of the smooth surface. These results support some of the observations made with the Seasat spaceborne imaging radar over flooded regions with heavy vegetation cover.

  13. Capillary waves in an inhomogeneous three-layer liquid with a free surface

    NASA Astrophysics Data System (ADS)

    Shiryaeva, S. O.; Grigor'ev, A. I.; Zav'yalov, D. A.

    2016-06-01

    In the domain of capillary waves, a bicubic dispersion relation is derived and analyzed for surface and internal capillary-gravitational waves in a three-layer liquid with a free surface. It is shown that the ratio of the internal wave amplitudes to the surface wave amplitudes is fairly large if the trivial condition of a "homogeneous liquid" is discarded. The amplitude ratio between the internal waves themselves (generated at different interfaces) may be both greater and smaller than unity depending on the physical parameters of the system. Specifically, it strongly depends on the densities of the layers and their thicknesses.

  14. Layer-by-layer generation of PEG-based regenerable immunosensing surfaces for small-sized analytes.

    PubMed

    Huebner, Maria; Ben Haddada, Maroua; Méthivier, Christophe; Niessner, Reinhard; Knopp, Dietmar; Boujday, Souhir

    2015-05-15

    Small molecules (haptens) like pharmaceuticals or peptides can serve as targets for antibody binding in competitive immunoassay-based flow-through assays. In this work, a strategy for preparing polyethylene glycol (PEG) coatings for subsequent hapten immobilization on glass-type silica surfaces is presented and characterized in detail. Two substrates bearing terminal silanol groups were utilized, a glass slide and a silicon wafer. First, surfaces were thoroughly cleaned and pretreated to generate additional silanol groups. Then, a silane layer with terminal epoxy groups was created using 3-glycidyloxypropyltrimethoxysilane (GOPTS). Epoxy groups were used to bind a layer of diamino-poly(ethylene glycol) (DAPEG) with terminal amino groups. Finally, the low molecular weight compound diclofenac was bound to the surface to be used as model ligand for competitive biosensing of haptens. The elementary steps were characterized using atomic force microscopy (AFM), water contact angle measurement, grazing-angle attenuated total reflection (GA-ATR) FT-IR spectroscopy, and X-ray photoelectron spectroscopy (XPS). The data collected using these techniques have confirmed the successive grafting of the molecular species, evidencing, that homogeneous monolayers were created on the silica surfaces and validated the proposed mechanism of functionalization. The resulting surfaces were used to investigate polyclonal anti-diclofenac antibodies recognition and reversibility using quartz crystal microbalance with dissipation (QCM-D) measurements or an automated flow-through immunoassay with chemiluminescence (CL) read-out. For both techniques, recognition and reversibility of the antibody binding were observed. The stability of sensors over time was also assessed and no decrease in CL response was observed upon 14 days in aqueous solution. The herein presented strategy for surface functionalization can be used in the future as reproducible and reusable universal platform for hapten

  15. Seasonality of submesoscale flows in the ocean surface boundary layer

    NASA Astrophysics Data System (ADS)

    Buckingham, Christian E.; Naveira Garabato, Alberto C.; Thompson, Andrew F.; Brannigan, Liam; Lazar, Ayah; Marshall, David P.; George Nurser, A. J.; Damerell, Gillian; Heywood, Karen J.; Belcher, Stephen E.

    2016-03-01

    A signature of submesoscale flows in the upper ocean is skewness in the distribution of relative vorticity. Expected to result for high Rossby number flows, such skewness has implications for mixing, dissipation, and stratification within the upper ocean. An array of moorings deployed in the Northeast Atlantic for 1 year as part of the experiment of the Ocean Surface Mixing, Ocean Submesoscale Interaction Study (OSMOSIS) reveals that relative vorticity is positively skewed during winter even though the scale of the Rossby number is less than 0.5. Furthermore, this skewness is reduced to zero during spring and autumn. There is also evidence of modest seasonal variations in the gradient Rossby number. The proposed mechanism by which relative vorticity is skewed is that the ratio of lateral to vertical buoyancy gradients, as summarized by the inverse gradient Richardson number, restricts its range during winter but less so at other times of the year. These results support recent observations and model simulations suggesting that the upper ocean is host to a seasonal cycle in submesoscale turbulence.

  16. Helicity and potential vorticity in the surface boundary layer turbulence

    NASA Astrophysics Data System (ADS)

    Chkhetiani, Otto; Kurgansky, Michael; Koprov, Boris; Koprov, Victor

    2016-04-01

    An experimental measurement of all three components of the velocity and vorticity vectors, as well as the temperature and its gradient, and potential vorticity, has been developed using four acoustic anemometers. Anemometers were placed at vertices of a tetrahedron, the horizontal base of which was a rectangular triangle with equal legs, and the upper point was exactly above the top of the right angle. The distance from the surface to the tetrahedron its base was 5.5 m, and the lengths of legs and a vertical edge were 5 m. The measurements were carried out of total duration near 100 hours both in stable and unstable stratification conditions (at the Tsimlyansk Scientific Station in a uniform area of virgin steppe 700 x 650 m, August 2012). A covariance-correlation matrix for turbulent variations in all measured values has been calculated. In the daytime horizontal and vertical components of the helicity are of the order of -0.03 and +0.01 m s-2, respectively. The nighttime signs remain unchanged, but the absolute values are several times smaller. It is confirmed also by statistics of a relative helicity. The cospectra and spectral correlation coefficients have been calculated for all helicity components. The time variations in the components of "instantaneous" relative helicity and potential vorticity are considered. Connections of helicity with Monin-Obukhov length and the wind vertical profile structure are discussed. This work was supported by the Russian Science Foundation (Project No 14-27-00134).

  17. Structure of the surface layer of the methanogenic archaean Methanosarcina acetivorans

    SciTech Connect

    Arbing, Mark A.; Chan, Sum; Shin, Annie; Phan, Tung; Ahn, Christine J.; Rohlin, Lars; Gunsalus, Robert P.

    2012-09-05

    Archaea have a self-assembling proteinaceous surface (S-) layer as the primary and outermost boundary of their cell envelopes. The S-layer maintains structural rigidity, protects the organism from adverse environmental elements, and yet provides access to all essential nutrients. We have determined the crystal structure of one of the two 'homologous' tandem polypeptide repeats that comprise the Methanosarcina acetivorans S-layer protein and propose a high-resolution model for a microbial S-layer. The molecular features of our hexameric S-layer model recapitulate those visualized by medium resolution electron microscopy studies of microbial S-layers and greatly expand our molecular view of S-layer dimensions, porosity, and symmetry. The S-layer model reveals a negatively charged molecular sieve that presents both a charge and size barrier to restrict access to the cell periplasmic-like space. The {beta}-sandwich folds of the S-layer protein are structurally homologous to eukaryotic virus envelope proteins, suggesting that Archaea and viruses have arrived at a common solution for protective envelope structures. These results provide insight into the evolutionary origins of primitive cell envelope structures, of which the S-layer is considered to be among the most primitive: it also provides a platform for the development of self-assembling nanomaterials with diverse functional and structural properties.

  18. Pseudomonas aeruginosa Pili and Flagella Mediate Distinct Binding and Signaling Events at the Apical and Basolateral Surface of Airway Epithelium

    PubMed Central

    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

  19. Dynamics of cathode spots in low-pressure arc plasma removing oxide layer on steel surfaces

    NASA Astrophysics Data System (ADS)

    Tang, Z. L.; Yang, K.; Liu, H. X.; Zhang, Y. C.; Li, H.; Zhu, X. D.

    2016-03-01

    The dynamics of cathode spots has been investigated in low-pressure arc plasma for removing oxide layer on low carbon steel surfaces. The motion of cathode spots was observed with a high speed camera, and the arc voltage was analyzed by fast Fourier transform. The spots move on clean steel surface as a random walk, and the low-frequency components dominated the voltage waveform. However, the spots on steel surfaces with oxide layer tend to burn on the rim of the eroded area formed in the previous arcing, and the low-frequency components decrease correspondingly. The "color" of the colored random noise for arc voltage varies from the approximate brown noise for clean steel surface to pink noise for thick oxide layer, where the edge effect of boundary is considered to play a significant role.

  20. Electronic absorption band broadening and surface roughening of phthalocyanine double layers by saturated solvent vapor treatment

    SciTech Connect

    Kim, Jinhyun; Yim, Sanggyu

    2012-10-15

    Variations in the electronic absorption (EA) and surface morphology of three types of phthalocyanine (Pc) thin film systems, i.e. copper phthalocyanine (CuPc) single layer, zinc phthalocyanine (ZnPc) single layer, and ZnPc on CuPc (CuPc/ZnPc) double layer film, treated with saturated acetone vapor were investigated. For the treated CuPc single layer film, the surface roughness slightly increased and bundles of nanorods were formed, while the EA varied little. In contrast, for the ZnPc single layer film, the relatively high solubility of ZnPc led to a considerable shift in the absorption bands as well as a large increase in the surface roughness and formation of long and wide nano-beams, indicating a part of the ZnPc molecules dissolved in acetone, which altered their molecular stacking. For the CuPc/ZnPc film, the saturated acetone vapor treatment resulted in morphological changes in mainly the upper ZnPc layer due to the significantly low solubility of the underlying CuPc layer. The treatment also broadened the EA band, which involved a combination of unchanged CuPc and changed ZnPc absorption.

  1. Surface deformation and geoid anomalies over single and double-layered convective systems

    NASA Technical Reports Server (NTRS)

    Koch, M.; Yuen, D. A.

    1985-01-01

    Using a primitive variable formulation of the finite-element method, the differences in the surface observables, such as topography and geoid, produced by single- and double-layered thermal convection, were compared. Both constant and depth-dependent viscosities have been considered. For the same Rayleigh number, larger surface perturbations are produced by single-cell convection. For the same Nusselt number, the magnitudes of the surface observables are greater for double-layered convection. For the same surface heat-flux, surface topographies have similar magnitudes, but the relative amplitudes of geoid anomalies depend greatly on the style of viscosity stratification. This difference in the geoid between the two systems increases with greater surface heat-flow, regardless of viscosity structure.

  2. Thermocouple Rakes for Measuring Boundary Layer Flows Extremely Close to Surface

    NASA Technical Reports Server (NTRS)

    Hwang, Danny P.; Fralick, Gustave C.; Martin, Lisa C.; Blaha, Charles A.

    2001-01-01

    Of vital interest to aerodynamic researchers is precise knowledge of the flow velocity profile next to the surface. This information is needed for turbulence model development and the calculation of viscous shear force. Though many instruments can determine the flow velocity profile near the surface, none of them can make measurements closer than approximately 0.01 in. from the surface. The thermocouple boundary-layer rake can measure much closer to the surface than conventional instruments can, such as a total pressure boundary layer rake, hot wire, or hot film. By embedding the sensors (thermocouples) in the region where the velocity is equivalent to the velocity ahead of a constant thickness strut, the boundary-layer flow profile can be obtained. The present device fabricated at the NASA Glenn Research Center microsystem clean room has a heater made of platinum and thermocouples made of platinum and gold. Equal numbers of thermocouples are placed both upstream and downstream of the heater, so that the voltage generated by each pair at the same distance from the surface is indicative of the difference in temperature between the upstream and downstream thermocouple locations. This voltage differential is a function of the flow velocity, and like the conventional total pressure rake, it can provide the velocity profile. In order to measure flow extremely close to the surface, the strut is made of fused quartz with extremely low heat conductivity. A large size thermocouple boundary layer rake is shown in the following photo. The latest medium size sensors already provide smooth velocity profiles well into the boundary layer, as close as 0.0025 in. from the surface. This is about 4 times closer to the surface than the previously used total pressure rakes. This device also has the advantage of providing the flow profile of separated flow and also it is possible to measure simultaneous turbulence levels within the boundary layer.

  3. A Numerical Model of Viscoelastic Layer Entrainment by Airflow in Cough

    NASA Astrophysics Data System (ADS)

    Mitran, Sorin M.

    2008-07-01

    Coughing is an alternative mode of ensuring mucus clearance in the lung when normal cilia induced flow breaks down. A numerical model of this process is presented with the following aspects. (1) A portion of the airway comprising the first three bronchus generations is modeled as radially reinforced elastic tubes. Elasticity equations are solved to predict airway deformation under effect of airway pressure. (2) The compressible, turbulent flow induced by rapid lung contraction is modeled by direct numerical simulation for Reynolds numbers in the range 5,000-10,000 and by Large Eddy Simulation for Reynolds numbers in the range 5,000-40,000. (3) A two-layer model of the airway surface liquid (ASL) covering the airway epithelial layer is used. The periciliary liquid (PCL) in direct contact with the epithelial layer is considered to be a Newtonian fluid. Forces modeling cilia beating can act upon this layer. The mucus layer between the PCL and the interior airflow is modeled as an Oldroyd-B fluid. The overall computation is a fluid-structure interaction simulation that tracks changes in ASL thickness and airway diameters that result from impulsive airflow boundary conditions imposed at bronchi ends. In particular, the amount of mucus that is evacuated from the system is computed as a function of cough intensity and mucus rheological properties.

  4. Laser-induced oxidation of titanium substrate: Analysis of the physicochemical structure of the surface and sub-surface layers

    NASA Astrophysics Data System (ADS)

    Antończak, Arkadiusz J.; Skowroński, Łukasz; Trzcinski, Marek; Kinzhybalo, Vasyl V.; Łazarek, Łukasz K.; Abramski, Krzysztof M.

    2015-01-01

    This paper presents the results of the analysis of the complex chemical structure of the layers made on titanium in the process of the heating of its surfaces in an atmospheric environment, by irradiating samples with a nanosecond-pulsed laser. The study was carried out for electroplated, high purity, polycrystalline titanium substrates using a Yb:glass fiber laser. All measurements were made for samples irradiated in a broad range of accumulated fluence, below the ablation threshold. It has been determined how the complex index of refraction of both the oxynitride layers and the substrate vary as a function of accumulated laser fluence. It was also shown that the top layer of the film produced on titanium, which is transparent, is not a pure TiO2 as had been supposed before. The XPS and XRD analyses confirmed the presence of nitrogen compounds and the existence of nonstoichiometric compounds. By sputtering of the sample's surface using an Ar+ ion gun, the changes in the concentration of individual elements as a function of the layer's cross-section were determined. Lastly, an analysis of the surface morphology has also been carried out, explaining why the layers crack and exfoliate from their substrate.

  5. TEM studies of the nitrided/oxided Ni-Ti surface layer.

    PubMed

    Lelatko, J; Goryczka, T; Paczkowski, P; Wierzchoń, T; Morawiec, H

    2010-03-01

    TiN and TiO(2) coatings, which are known from their low chemical reactivity, high hardness and wear and corrosion resistance, are used for protecting the NiTi surface. In the present work, nearly equiatomic NiTi (50.6 at.%) shape memory alloy was covered with the layers obtained by nitriding under glow discharge at 1073 K. Additionally, at the end of the process some amount of oxygen was added. Characterization of the nitrided/oxided layers structure was carried out using transmission and scanning electron microscopy. The investigations were focused on the structure of the multilayer nitrided/oxided NiTi surface. The surface is formed from nanocrystalline and columnar grains of the TiN phase. Between the top layer and beta-NiTi substrate the interface Ti(2)Ni layer was formed. Addition of oxygen at the end of the process created a thin layer of TiO(2) phase nanograins at the surface of the TiN phase. In the same areas, small amount of amorphous phase was identified. The combination of nitriding and oxidation formed layers that reveal relatively high corrosion resistance. PMID:20500413

  6. Thin gold layer in NiCo and Ni electroforming process: optical surface characterization

    NASA Astrophysics Data System (ADS)

    Sironi, G.; Spiga, D.; Raimondi, L.; Pareschi, G.; Orlandi, A.; Borghi, G.; Missaglia, N.; Negri, B.

    2010-07-01

    Mandrel replication by NiCo electroforming is an upgrade of the well-suited X-ray mirrors manufacturing process with pure Nickel. In this process, a Gold layer deposited on the mandrel acts as release agent and, at the same time, as reflective coating. To increase the optical performances of X-ray mirrors, the replicated optical surface is meant to reproduce the smooth topography of the mandrel: a surface degradation is commonly observed, indeed. A factor leading to surface smoothness worsening can be the spontaneous roughness growth of the Gold layer itself; therefore, the optical quality of the reflecting surface might be improved by optimizing the Gold layer thickness. A preliminary study, aimed at investigating the effects of Gold thickness reduction (< 100 nm Vs. the usual 200 nm), had already been dealt in the spectral range 0.02-1000 μm: measurements performed on flat electroformed samples showed that the Gold thickness reduction chiefly affects the roughness around 1 μm. Here we presents a study of the effectiveness of a Gold layer with reduced (< 100 nm) thickness in the NiCo X-ray mirrors electroforming, aimed at surface micro-roughness mitigation. The characterization, in the spectral range 0.02-1000 μm, of 3 X-ray mirrors manufactured utilizing Gold layers with different thickness values from a flight mandrel is reported. The performed investigation is organized as follows: (a) characterization of the flight mandrel; (b) dependence of the micro-roughness from different Gold layers thicknesses supported by XRD study; (c) comparison of the micro-roughness of mirrors manufactured in NiCo in Ni, with the same Gold layer thickness. As a conclusive remark the effects of the Gold layer thinning on the angular degradation at high energy are reported.

  7. A critical study of the role of the surface oxide layer in titanium bonding

    NASA Technical Reports Server (NTRS)

    Dias, S.; Wightman, J. P.

    1982-01-01

    The molecular understanding of the role which the surface oxide layer of the adherend plays in titanium bonding is studied. The effects of Ti6-4 adherends pretreatment, bonding conditions, and thermal aging of the lap shear specimens were studied. The use of the SEM/EDAX and ESCA techniques to study surface morphology and surface composition was emphasized. In addition, contact angles and both infrared and visible reflection spectroscopy were used in ancillary studies.

  8. Mechanisms of drag reduction of superhydrophobic surfaces in a turbulent boundary layer flow

    NASA Astrophysics Data System (ADS)

    Zhang, Jingxian; Tian, Haiping; Yao, Zhaohui; Hao, Pengfei; Jiang, Nan

    2015-09-01

    The drag-reducing property of a superhydrophobic surface is investigated along with its mechanism. A superhydrophobic surface with micro-nanotextures is fabricated and tested using SEM and contact angle measurement. Velocity distributions in the turbulent boundary layer with a superhydrophobic surface and a smooth surface are measured by particle image velocimetry at Re θ = 810, 990, and 1220. An upward lift effect on the velocity profile caused by the rugged air layer on the superhydrophobic surface is observed, which indicates drag reduction. Estimated by the wall shear stress, a drag reduction of 10.1, 20.7, and 24.1 % is observed for Re θ equal to 810, 990, and 1220, respectively. The drag reduction is caused mainly by slip on the interface and modifications in the turbulent structures, and the latter plays a more important role as Re θ increases. Suppressions are observed in turbulence intensities, and reductions in the total Reynolds shear stress T {turb/+} are 2.5, 18.5, and 23.1 % for Re θ = 810, 990, and 1220, respectively. Vortex fields above the superhydrophobic and smooth surfaces at Re θ = 990 are investigated. Vortexes are weakened and lifted upward by the superhydrophobic surface, and the position of the maximum swirling strength is lifted 0.17 δ ( δ is the boundary layer thickness) upward in the wall-normal direction. This modification in turbulence structures contributes significantly to the drag reduction in the turbulent boundary layer flow.

  9. Insight in layer-by-layer assembly of cysteamine and L-cysteine on the copper surface by electrochemistry and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Song, Ping; Shen, Shu; Li, Chuan-Chuan; Guo, Xiao-Yu; Wen, Ying; Yang, Hai-Feng

    2015-02-01

    In this work, we examined the relationship between the anticorrosion behavior and the structure of the cysteamine/L-cysteine layer-by-layer coating on the copper surface via the self-assembled monolayers (SAMs) technique with electrochemistry and surface-enhanced Raman scattering (SERS) spectroscopy. SERS results elucidated the layer-by-layer adsorption mechanism of cysteamine/L-cysteine at the copper surface. Electrochemical investigations explored the inhibition behavior of cysteamine/L-cysteine for copper from corrosion with a high protection efficiency of 91.4%.

  10. Effects of mixed discrete surface charges on the electrical double layer.

    PubMed

    Jiménez-Ángeles, Felipe

    2012-08-01

    Adsorption of surface coions and charge reversal are induced at the electrical double layer of a wall charged with positive and negative surface sites next to an electrolyte solution. While for the considered surface charge density these effects are found over a wide range of conditions, they are not observed for the typically employed surface models in equivalent conditions. Important consequences in electrophoresis experiments for different colloids with equal effective surface charge density are foreseen. This study is carried out by means of molecular dynamics simulations. PMID:23005771

  11. Relevance of glycosylation of S-layer proteins for cell surface properties

    PubMed Central

    Schuster, Bernhard; Sleytr, Uwe B.

    2015-01-01

    Elucidating the building principles and intrinsic features modulating certain water-associated processes (e.g., surface roughness in the nanometer scale, surface hydration and accompanied antifouling property, etc.) of surface structures from (micro)organisms is nowadays a highly challenging task in fields like microbiology, biomimetic engineering and (bio)material sciences. Here, we show for the first time the recrystallization of the wild-type S-layer glycoprotein wtSgsE from Geobacillus stearothermophilus NRS 2004/3a and its recombinantly produced non-glycosylated form, rSgsE, on gold sensor surfaces. Whereas the proteinaceous lattice of the S-layer proteins is forming a rigid layer on the sensor surface, the glycan chains are developing an overall soft, highly dissipative film. Interestingly, to the wtSgsE lattice almost twice the amount of water is bound and/or coupled in comparison with the non-glycosylated rSgsE with the preferred region being the extending glycan residues. The present results are discussed in terms of the effect of the glycan residues on the recrystallization, the adjoining hydration layer, and the nanoscale roughness and fluidic behavior. The latter features may turn out to be one of the most general ones among bacterial and archaeal S-layer lattices. PMID:25818946

  12. Relevance of glycosylation of S-layer proteins for cell surface properties.

    PubMed

    Schuster, Bernhard; Sleytr, Uwe B

    2015-06-01

    Elucidating the building principles and intrinsic features modulating certain water-associated processes (e.g., surface roughness in the nanometer scale, surface hydration and accompanied antifouling property, etc.) of surface structures from (micro)organisms is nowadays a highly challenging task in fields like microbiology, biomimetic engineering and (bio)material sciences. Here, we show for the first time the recrystallization of the wild-type S-layer glycoprotein wtSgsE from Geobacillus stearothermophilus NRS 2004/3a and its recombinantly produced non-glycosylated form, rSgsE, on gold sensor surfaces. Whereas the proteinaceous lattice of the S-layer proteins is forming a rigid layer on the sensor surface, the glycan chains are developing an overall soft, highly dissipative film. Interestingly, to the wtSgsE lattice almost twice the amount of water is bound and/or coupled in comparison with the non-glycosylated rSgsE with the preferred region being the extending glycan residues. The present results are discussed in terms of the effect of the glycan residues on the recrystallization, the adjoining hydration layer, and the nanoscale roughness and fluidic behavior. The latter features may turn out to be one of the most general ones among bacterial and archaeal S-layer lattices. PMID:25818946

  13. Surface (S)-layer proteins of Deinococcus radiodurans and their utility as vehicles for surface localization of functional proteins.

    PubMed

    Misra, Chitra Seetharam; Basu, Bhakti; Apte, Shree Kumar

    2015-12-01

    The radiation resistant bacterium, Deinococcus radiodurans contains two major surface (S)-layer proteins, Hpi and SlpA. The Hpi protein was shown to (a) undergo specific in vivo cleavage, and (b) closely associate with the SlpA protein. Using a non-specific acid phosphatase from Salmonella enterica serovar Typhi, PhoN as a reporter, the Surface Layer Homology (SLH) domain of SlpA was shown to bind deinococcal peptidoglycan-containing cell wall sacculi. The association of SlpA with Hpi on one side and peptidoglycan on the other, localizes this protein in the 'interstitial' layer of the deinoccocal cell wall. Gene chimeras of hpi-phoN and slh-phoN were constructed to test efficacy of S-layer proteins, as vehicles for cell surface localization in D. radiodurans. The Hpi-PhoN protein localized exclusively in the membrane fraction, and displayed cell-based phosphatase activity in vivo. The SLH-PhoN, which localized to both cytosolic and membrane fractions, displayed in vitro activity but no cell-based in vivo activity. Hpi, therefore, emerged as an efficient surface localizing protein and can be exploited for suitable applications of this superbug. PMID:26450150

  14. Effect of surface energy and seed layer annealing temperature on ZnO seed layer formation and ZnO nanowire growth

    NASA Astrophysics Data System (ADS)

    Park, Ji-Sub; Mahmud, Imtiaz; Shin, Han Jae; Park, Min-Kyu; Ranjkesh, Amid; Lee, Do Kyung; Kim, Hak-Rin

    2016-01-01

    We discuss the effects of surface energy and seed layer annealing temperature (Tannealing) on seed layer growth and hydrothermally-grown zinc oxide (ZnO) nanowires (NWs). In this work, by varying the ultraviolet ozone (UVO) treatment times on a silicon surface, the surface energy conditions for the seed layer formation changed and the seed layer was annealed under different Tannealing conditions. Under a lower surface energy condition of the substrate, with increasing Tannealing, the coverage density and the average thickness of the seed layer increased, but island-like growth was observed. This case was inevitably accompanied by an increase in surface roughness, which resulted in agglomerated low density growth of ZnO NWs. After sufficient UVO treatment, hydroxyl groups on the silicon surface activated the ZnO seed layer formation in the chemical reaction and increased the bonding energy between the active nucleation sites of the seed layer and the substrate surface. This ensured higher coverage density of the seed layer with lower surface roughness under the same Tannealing condition, thereby providing the ZnO NW growth with an enhanced density and aspect ratio as well as good crystallinity.

  15. Influence of surface forcing on near-surface and mixing layer turbulence in the tropical Indian Ocean

    NASA Astrophysics Data System (ADS)

    Callaghan, Adrian H.; Ward, Brian; Vialard, Jérôme

    2014-12-01

    An autonomous upwardly-moving microstructure profiler was used to collect measurements of the rate of dissipation of turbulent kinetic energy (ε) in the tropical Indian Ocean during a single diurnal cycle, from about 50 m depth to the sea surface. This dataset is one of only a few to resolve upper ocean ε over a diurnal cycle from below the active mixing layer up to the air-sea interface. Wind speed was weak with an average value of ~5 m s-1 and the wave field was swell-dominated. Within the wind and wave affected surface layer (WWSL), ε values were on the order of 10-7-10-6 W kg-1 at a depth of 0.75 m and when averaged, were almost a factor of two above classical law of the wall theory, possibly indicative of an additional source of energy from the wave field. Below this depth, ε values were closer to wall layer scaling, suggesting that the work of the Reynolds stress on the wind-induced vertical shear was the major source of turbulence within this layer. No evidence of persistent elevated near-surface ε characteristic of wave-breaking conditions was found. Profiles collected during night-time displayed relatively constant ε values at depths between the WWSL and the base of the mixing layer, characteristic of mixing by convective overturning. Within the remnant layer, depth-averaged values of ε started decaying exponentially with an e-folding time of 47 min, about 30 min after the reversal of the total surface net heat flux from oceanic loss to gain.

  16. Study of the amorphization of surface silicon layers implanted by low-energy helium ions

    NASA Astrophysics Data System (ADS)

    Lomov, A. A.; Myakon'kikh, A. V.; Oreshko, A. P.; Shemukhin, A. A.

    2016-03-01

    The structural changes in surface layers of Si(001) substrates subjected to plasma-immersion implantation by (2-5)-keV helium ions to a dose of D = 6 × 1015-5 × 1017 cm-2 have been studied by highresolution X-ray diffraction, Rutherford backscattering, and spectral ellipsometry. It is found that the joint application of these methods makes it possible to determine the density depth distribution ρ( z) in an implanted layer, its phase state, and elemental composition. Treatment of silicon substrates in helium plasma to doses of 6 × 1016 cm-2 leads to the formation of a 20- to 30-nm-thick amorphized surface layer with a density close to the silicon density. An increase in the helium dose causes the formation of an internal porous layer.

  17. Aerodynamically-driven condensate layer thickness distributions on isothermal cylindrical surfaces

    NASA Technical Reports Server (NTRS)

    Rosner, D. E.; Gunes, D.; Nazih-Anous, N.

    1983-01-01

    A simple yet rather general mathematical model is presented for predicting the distribution of condensate layer thickness when aerodynamic shear is the dominant mechanism of liquid flow along the surface. The Newtonian condensate film is treated using well-known thin-layer (lubrication theory) approximations, and condensate supply is taken to be the result of either convective diffusion or inertial impaction. Illustrative calculations for a circular cylinder in a crossflow at Re = 100,000 reveal the consequences of alternate condensate arrival mechanisms and the existence of thicker reverse-flow films behind the position of gas boundary-layer separation. The present formulation is readily generalized to include transient liquid layer flows on noncircular objects of variable surface temperature, as encountered in turbine-blade materials testing or operation.

  18. Hard Coat Layers by PE-CVD Process for the Top Surface of Touch Panel

    NASA Astrophysics Data System (ADS)

    Okunishi, T.; Sato, N.; Yazawa, K.

    2013-06-01

    In order to protect surface from damages, the high pencil hardness and the high abrasion resistance are required for the hard coat layers on polyethylene telephthalate (PET) films for the application of touch panel surface. We have already found that the UV-curing-hard-coat-polymer (UHP) coated PET films show the poor abrasion resistance, while they have the high pencil hardness. It reveals that the abrasion resistance of hard coat layers of the UHP is not simply dependent on the pencil hardness. In this work, we have studied to improve the abrasion resistance of SiOC films as hard coat layers, which were formed by PE-CVD process on UHP coated PET. The abrasion resistance was evaluated by Taber abrasion test. PE-CVD hard coat layers which formed on UHP coater PET films have showed the better abrasion resistance and have the possibility of substitution to the thin glass sheets for touch panel application.

  19. Electrical conductivity of reconstructed Si(111) surface with sodium-doped C{sub 60} layers

    SciTech Connect

    Tsukanov, D. A. Saranin, A. A.; Ryzhkova, M. V.; Borisenko, E. A.; Zotov, A. V.

    2015-01-05

    Electrical conductance of sodium-doped C{sub 60} ultra-thin layers (1–6 monolayers) grown on the Na-adsorbed Si(111)√3 × √3-Au surface has been studied in situ by four-point probe technique, combined with low-energy electron diffraction observations. Evidence of conductance channel formation through the C{sub 60} ultrathin layer is demonstrated as a result of Na dosing of 3 and 6 monolayers thick C{sub 60} layers. The observed changes in surface conductivity can be attributed to the formation of fulleride-like NaC{sub 60} and Na{sub 2}C{sub 60} compound layers.

  20. Computer graphic visualization of orbiter lower surface boundary-layer transition

    NASA Technical Reports Server (NTRS)

    Throckmorton, D. A.; Hartung, L. C.

    1984-01-01

    Computer graphic techniques are applied to the processing of Shuttle Orbiter flight data in order to create a visual presentation of the extent and movement of the boundary-layer transition front over the orbiter lower surface during entry. Flight-measured surface temperature-time histories define the onset and completion of the boundary-layer transition process at any measurement location. The locus of points which define the spatial position of the boundary-layer transition front on the orbiter planform is plotted at each discrete time for which flight data are available. Displaying these images sequentially in real-time results in an animated simulation of the in-flight boundary-layer transition process.

  1. Surface structure and surface kinetics of InN grown by plasma-assisted atomic layer epitaxy: A HREELS study

    SciTech Connect

    Acharya, Ananta R. E-mail: anantaach@gmail.com; Thoms, Brian D.; Nepal, Neeraj; Eddy, Charles R.

    2015-03-15

    The surface bonding configuration and kinetics of hydrogen desorption from InN grown by plasma-assisted atomic layer epitaxy have been investigated. High resolution electron energy loss spectra exhibited loss peaks assigned to a Fuchs–Kliewer surface phonon, N-N and N-H surface species. The surface N-N vibrations are attributed to surface defects. The observation of N-H but no In-H surface species suggested N-terminated InN. Isothermal desorption data were best fit by the first-order desorption kinetics with an activation energy of (0.88 ± 0.06) eV and pre-exponential factor of (1.5 ± 0.5) × 10{sup 5 }s{sup −1}.

  2. Cell surface display of chimeric glycoproteins via the S-layer of Paenibacillus alvei

    PubMed Central

    Zarschler, Kristof; Janesch, Bettina; Kainz, Birgit; Ristl, Robin; Messner, Paul; Schäffer, Christina

    2015-01-01

    The Gram-positive, mesophilic bacterium Paenibacillus alvei CCM 2051T possesses a two-dimensional crystalline protein surface layer (S-layer) with oblique lattice symmetry composed of a single type of O-glycoprotein species. Herein, we describe a strategy for nanopatterned in vivo cell surface co-display of peptide and glycan epitopes based on this S-layer glycoprotein self-assembly system. The open reading frame of the corresponding structural gene spaA codes for a protein of 983 amino acids, including a signal peptide of 24 amino acids. The mature S-layer protein has a theoretical molecular mass of 105.95 kDa and a calculated pI of 5.83. It contains three S-layer homology domains at the N-terminus that are involved in anchoring of the glycoprotein via a non-classical, pyruvylated secondary cell wall polymer to the peptidoglycan layer of the cell wall. For this polymer, several putative biosynthesis enzymes were identified upstream of the spaA gene. For in vivo cell surface display, the hexahistidine tag and the enhanced green fluorescent protein, respectively, were translationally fused to the C-terminus of SpaA. Immunoblot analysis, immunofluorescence staining, and fluorescence microscopy revealed that the fused epitopes were efficiently expressed and successfully displayed via the S-layer glycoprotein matrix on the surface of P. alvei CCM 2051T cells. In contrast, exclusively non-glycosylated chimeric SpaA proteins were displayed, when the S-layer of the glycosylation-deficient wsfP mutant was used as a display matrix. PMID:20513375

  3. Cell surface display of chimeric glycoproteins via the S-layer of Paenibacillus alvei.

    PubMed

    Zarschler, Kristof; Janesch, Bettina; Kainz, Birgit; Ristl, Robin; Messner, Paul; Schäffer, Christina

    2010-07-01

    The Gram-positive, mesophilic bacterium Paenibacillus alvei CCM 2051(T) possesses a two-dimensional crystalline protein surface layer (S-layer) with oblique lattice symmetry composed of a single type of O-glycoprotein species. Herein, we describe a strategy for nanopatterned in vivo cell surface co-display of peptide and glycan epitopes based on this S-layer glycoprotein self-assembly system. The open reading frame of the corresponding structural gene spaA codes for a protein of 983 amino acids, including a signal peptide of 24 amino acids. The mature S-layer protein has a theoretical molecular mass of 105.95kDa and a calculated pI of 5.83. It contains three S-layer homology domains at the N-terminus that are involved in anchoring of the glycoprotein via a non-classical, pyruvylated secondary cell wall polymer to the peptidoglycan layer of the cell wall. For this polymer, several putative biosynthesis enzymes were identified upstream of the spaA gene. For in vivo cell surface display, the hexahistidine tag and the enhanced green fluorescent protein, respectively, were translationally fused to the C-terminus of SpaA. Immunoblot analysis, immunofluorescence staining, and fluorescence microscopy revealed that the fused epitopes were efficiently expressed and successfully displayed via the S-layer glycoprotein matrix on the surface of P. alvei CCM 2051(T) cells. In contrast, exclusively non-glycosylated chimeric SpaA proteins were displayed, when the S-layer of the glycosylation-deficient wsfP mutant was used as a display matrix. PMID:20513375

  4. Investigation of mucus transport in an idealized lung airway model using multiphase CFD analysis

    NASA Astrophysics Data System (ADS)

    Rajendran, Rahul; Banerjee, Arindam

    2015-11-01

    Mucus, a Bingham fluid is transported in the pulmonary airways by consistent beating of the cilia and exhibits a wide range of physical properties in response to the core air flow and various pathological conditions. A better understanding of the interfacial instability is required as it plays a crucial role in gas transport, mixing, mucus clearance and drug delivery. In the current study, mucus is modelled as a Newtonian fluid and the two phase gas-liquid flow in the airways is investigated using an inhomogeneous Eulerian-Eulerian approach. The complex interface between the phases is tracked using the conventional VOF (Volume of Fluid) method. Results from our CFD simulations which are performed in idealized single and double bifurcation geometries will be presented and the influence of airflow rate, mucus layer thickness, mucus viscosity, airway geometry (branching & diameter) and surface tension on mucus flow behavior will be discussed. Mean mucus layer thickness, pressure drop due to momentum transfer & increased airway resistance, mucus transport speed and the flow morphology will be compared to existing experimental and theoretical data.

  5. Engineering Airway Epithelium

    PubMed Central

    Soleas, John P.; Paz, Ana; Marcus, Paula; McGuigan, Alison; Waddell, Thomas K.

    2012-01-01

    Airway epithelium is constantly presented with injurious signals, yet under healthy circumstances, the epithelium maintains its innate immune barrier and mucociliary elevator function. This suggests that airway epithelium has regenerative potential (I. R. Telford and C. F. Bridgman, 1990). In practice, however, airway regeneration is problematic because of slow turnover and dedifferentiation of epithelium thereby hindering regeneration and increasing time necessary for full maturation and function. Based on the anatomy and biology of the airway epithelium, a variety of tissue engineering tools available could be utilized to overcome the barriers currently seen in airway epithelial generation. This paper describes the structure, function, and repair mechanisms in native epithelium and highlights specific and manipulatable tissue engineering signals that could be of great use in the creation of artificial airway epithelium. PMID:22523471

  6. Synergistic effects of the Lactobacillus acidophilus surface layer and nisin on bacterial growth.

    PubMed

    Prado-Acosta, Mariano; Ruzal, Sandra M; Allievi, Mariana C; Palomino, María Mercedes; Sanchez Rivas, Carmen

    2010-02-01

    We have previously described a murein hydrolase activity for the surface layer (S-layer) of Lactobacillus acidophilus ATCC 4356. Here we show that, in combination with nisin, this S-layer acts synergistically to inhibit the growth of pathogenic Gram-negative Salmonella enterica and potential pathogenic Gram-positive bacteria, Staphylococcus aureus and Bacillus cereus. In addition, bacteriolytic effects were observed for the Gram-positive species tested. We postulate that the S-layer enhances the access of nisin into the cell membrane by enabling it to cross the cell wall, while nisin provides the sudden ion-nonspecific dissipation of the proton motive force required to enhance the S-layer murein hydrolase activity. PMID:19948852

  7. Magnetic field-related heating instabilities in the surface layers of the sun and stars

    NASA Technical Reports Server (NTRS)

    Ferrari, A.; Rosner, R.; Vaiana, G. S.

    1982-01-01

    The stability of a magnetized low-density plasma to current-driven filamentation instabilities is investigated and the results are applied to the surface layers of stars. Unlike previous studies, the initial (i.e., precoronal) state of the stellar surface atmosphere is taken to be a low-density, optically thin magnetized plasma in radiative equilibrium. The linear analysis shows that the surface layers of main-sequence stars (including the sun) which are threaded by magnetic fields are unstable; the instabilities considered lead to structuring perpendicular to the ambient magnetic fields. These results suggest that relatively modest surface motions, in conjunction with the presence of magnetic fields, suffice to account for the presence of inhomogeneous chromospheric and coronal plasma overlying a star's surface.

  8. Turbulent flow over a surface-mounted 2-D block in thermally-stratified boundary layers

    NASA Astrophysics Data System (ADS)

    Zhang, W.; Markfort, C. D.; Porte-Agel, F.

    2013-12-01

    Turbulent boundary-layer flows over complex topography have been of great interest in the atmospheric sciences and wind engineering communities. The geometry of the topography, surface characteristics and atmospheric thermal stability play important roles in determining momentum and scalar flux distribution. Studies of turbulent flow over simplified topography, such as 2-D or 3-D blocks and 2-D or 3-D sinusoidal hills, conducted under neutrally stratified boundary-layer conditions have provided insightful information of fluid dynamics. However, atmospheric thermal stability has rarely been incorporated into laboratory simulations, in particular, wind-tunnel experiments. Extension of such studies in thermally-stratified wind tunnels will fill this gap and advance our understanding of the underlying physics of flow over complex topography. Additionally, experimental data are useful for the development of new parameterizations for surface fluxes and validation of numerical models such as Large-Eddy Simulation (LES). A series of experiments involving neutral and thermally-stratified boundary-layer flows over a surface-mounted 2-D block, conducted at the Saint Anthony Falls Laboratory boundary-layer wind tunnel, will be presented. The 2-D block, with a width to height ratio of 2:1, occupied the lowest 25% of the turbulent boundary layer. Thermal stratification of the boundary layer was achieved by independently controlling the temperature of both the airflow, the test section floor and block surfaces. Measurements using high-resolution PIV, x-wire/cold-wire anemometry, thermal-couples and surface heat flux sensors were made to identify and quantify the turbulent flow properties, including the size of the recirculation zone, coherent vortex structures and the subsequent boundary layer recovery. Emphasis will be put on addressing thermal stability effects on momentum and scalar flux distribution.

  9. Hardening of the surface layers of commercial pure titanium VT1-0 under combined treatment

    NASA Astrophysics Data System (ADS)

    Bashchenko, Lyudmila P.; Gromov, Viktor E.; Budovskikh, Evgenii A.; Ivanov, Yurii F.; Soskova, Nina A.

    2015-10-01

    The treatment of VT1-0 titanium samples was carried out by concentrated energy fluxes. The combined treatment included surface carburizing with the joint use of powder samples of compounds with high physical and mechanical properties (namely, titanium diboride TiB2, silicon carbide SiC and zirconium oxide ZrO2) and subsequent electron beam treatment of surface layers formed in electroexplosive treatment. The combined treatment of surface layers resulted in the multifold increase in microhardness, which reduces depending on the depth of hardening zone. After electron-beam treatment, the depth of hardening zone is increased. During electron-beam treatment, the two-layer hardening zone forms.

  10. Scanning tunneling spectroscopy studies of angle-dependent van Hove singularities on twisted graphite surface layer

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Luo, Hong

    2013-12-01

    Slightly misoriented surface graphene layer on highly ordered pyrolytic graphite (HOPG) can result in Moiré patterns (MP). Two van Hove singularity (VHS) peaks in the density of states are observed with scanning tunneling spectroscopy on a series of the MPs with different periods on HOPG surface, flanking the Fermi energy. The energy difference between the two VHS peaks (ΔEVHS) is linearly proportional to the sine of interlayer rotation angle. A similar relation between ΔEVHS and MP periods has recently been reported on twisted graphene layers. Compared to the case of twisted graphene layers, the Fermi velocity of MPs on a HOPG surface is found to be larger, and the interlayer hopping is enhanced.

  11. Fabrication of TI/SIC Surface Nano-Composite Layer by Friction Stir Processing

    NASA Astrophysics Data System (ADS)

    Shamsipur, Ali; Kashani-Bozorg, Seyed Farshid; Zareie-Hanzaki, Abbas

    In the present investigation, novel Ti/SiC surface nano-composite layer was successfully fabricated by dispersing nano-sized SiC particles into commercially pure titanium plates employing friction stir processing technique. The process parameters such as tool rotation and advancing speeds were adjusted to produce defect-free surface composite layer, however, uniform distribution of the nano-size SiC particles in a matrix of titanium was achieved after the second pass. The micro hardness value of the Ti/SiC nano-composite surface layer was found to be 534 HV; this is 3.3 times higher than that of the commercially pure titanium substrate. No reaction was detected between SiC powders and the titanium matrix after friction stir processing.

  12. Enhancement of effective electromechanical coupling factor by mass loading in layered surface acoustic wave device structures

    NASA Astrophysics Data System (ADS)

    Tang, Gongbin; Han, Tao; Teshigahara, Akihiko; Iwaki, Takao; Hashimoto, Ken-ya

    2016-07-01

    This paper describes a drastic enhancement of the effective coupling factor K\\text{e}2 by mass loading in layered surface acoustic wave (SAW) device structures such as the ScAlN film/Si substrate structure. This phenomenon occurs when the piezoelectric layer exhibits a high acoustic wave velocity. The mass loading decreases the SAW velocity and causes SAW energy confinement close to the top surface where an interdigital transducer is placed. It is shown that this phenomenon is obvious even when an amorphous SiO2 film is deposited on the top surface for temperature compensation. This K\\text{e}2 enhancement was also found in various combinations of electrode, piezoelectric layer, and/or substrate materials. The existence of this phenomenon was verified experimentally using the ScAlN film/Si substrate structure.

  13. Synoptic classification and horizontal homogeneity of the refractive index structure function parameter in the surface layer

    NASA Astrophysics Data System (ADS)

    Boyle, P. J.; Davidson, K. L.

    1984-02-01

    This is a two part report. The first part describes an investigation of the feasibility of using the synoptic scale classification scheme described in the Refractive Effects Guidebook (REG) to predict the level of optical turbulence in the surface layer as measured by C sub n squared, the refractive index structure function parameter. Data were examined from nine experiments which took place in the north Pacific and north Atlantic. The measurement experiments spanned five years and included all four seasons. The REG appears to be useful in a limited way in predicting ranges of C sub n squared in the surface layer. Inclusion of local factors would increase predictability. The second part deals with horizontal homogeneity of the surface layer C sub n squared as measured during the JASIN experiment in the North Atlantic in 1978. Periods of homogeneity lasting between one and two days were encountered along 200 km sectors and for up to nine hours over the entire JASIN experimental area.

  14. On the influence of nanometer-thin antiferromagnetic surface layer on ferromagnetic CrO2

    NASA Astrophysics Data System (ADS)

    Das, P.; Bajpai, A.; Ohno, Y.; Ohno, H.; Müller, J.

    2012-09-01

    We investigate the influence of naturally grown 2-5 nm thin surface layer of antiferromagnetic (AFM) Cr2O3 on the half metallic ferromagnet CrO2 by measuring the magnetic behavior of a single micro-crystal. The temperature variation of the magnetic stray fields of the micro-crystal measured by micro-Hall magnetometry shows an anomalous increase below ˜60 K. We find clear evidence that this behavior is due to the influence of the AFM surface layer. The average amplitude of the Barkahausen jumps exhibits a similar temperature dependence indicating that the AFM surface layer plays a role in defining the potential landscape seen by the domain configuration in the ferromagnetic grain.

  15. Hardening of the surface layers of commercial pure titanium VT1-0 under combined treatment

    SciTech Connect

    Bashchenko, Lyudmila P. Gromov, Viktor E. Budovskikh, Evgenii A. Soskova, Nina A.; Ivanov, Yurii F.

    2015-10-27

    The treatment of VT1-0 titanium samples was carried out by concentrated energy fluxes. The combined treatment included surface carburizing with the joint use of powder samples of compounds with high physical and mechanical properties (namely, titanium diboride TiB{sub 2}, silicon carbide SiC and zirconium oxide ZrO{sub 2}) and subsequent electron beam treatment of surface layers formed in electroexplosive treatment. The combined treatment of surface layers resulted in the multifold increase in microhardness, which reduces depending on the depth of hardening zone. After electron-beam treatment, the depth of hardening zone is increased. During electron-beam treatment, the two-layer hardening zone forms.

  16. Manufacture of silicon-based devices having disordered sulfur-doped surface layers

    DOEpatents

    Carey, III; James Edward; Mazur, Eric

    2008-04-08

    The present invention provides methods of fabricating a radiation-absorbing semiconductor wafer by irradiating at least one surface location of a silicon substrate, e.g., an n-doped crystalline silicon, by a plurality of temporally short laser pulses, e.g., femtosecond pulses, while exposing that location to a substance, e.g., SF.sub.6, having an electron-donating constituent so as to generate a substantially disordered surface layer (i.e., a microstructured layer) that incorporates a concentration of that electron-donating constituent, e.g., sulfur. The substrate is also annealed at an elevated temperature and for a duration selected to enhance the charge carrier density in the surface layer. For example, the substrate can be annealed at a temperature in a range of about 700 K to about 900 K.

  17. Initial growth process of Co (Pd) layers on a Pd (Co) surface

    SciTech Connect

    Nishizawa, N. Porquez, J. G.; Munekata, H.; Kitamoto, Y.

    2015-05-07

    The deposition process of ultra-thin Co and Pd layers is studied using DC magnetron sputtering and ex situ atomic force microscopy (AFM). It is found that observation with AFM in the air atmosphere is reliable to discuss nucleation of Co and Pd crystallites. It is discussed that a Co ultra-thin layer is formed primarily through the process of two-dimensional island formation, whereas a Pd ultra-thin layer is formed through the process of mixed two- and three-dimensional island formation. On the basis of those results, Co/Pd multilayers having a flat top surface are prepared successfully.

  18. The effects of oxalate treatment on the smear layer of ground surfaces of human dentine.

    PubMed

    Pashley, D H; Galloway, S E

    1985-01-01

    The layer was evaluated by scanning electron microscopy and by measurement of hydraulic conductance before and after 2-min topical treatment with potassium chloride, neutral potassium oxalate, half-neutralized oxalic acid or both neutral and acidic oxalates. The treated smear layers were then re-evaluated microscopically and functionally both before and after acid challenge. The layers treated with KCl were not altered either microscopically or functionally and were susceptible to acid etching. Dentine surfaces treated with either oxalate solutions became less permeable and were acid-resistant. PMID:3866520

  19. Resonance oscillation damping of a scanning microscope probe by a near-surface viscous liquid layer

    NASA Astrophysics Data System (ADS)

    Maslenikov, I. I.; Reshetov, N. V.

    2016-05-01

    Viscous liquid layer motion between a probe with a tip shaped as a paraboloid of revolution and a surface is considered for semicontact-mode operation of a scanning probe microscope. The presence of a viscous liquid layer leads to energy dissipation and is one of the factors responsible for the decrease in the probe oscillation amplitude. The Reynolds equation for viscous liquid motion is used to obtain an analytic solution to the problem. The formula derived for the loss is compared with experimental data obtained for probes and layers with various curvature radii and viscosities.

  20. Tribological Properties of the Fe-Al-Cr Alloyed Layer by Double Glow Plasma Surface Metallurgy

    NASA Astrophysics Data System (ADS)

    Luo, Xixi; Yao, Zhengjun; Zhang, Pingze; Zhou, Keyin; Wang, Zhangzhong

    2016-07-01

    A Fe-Al-Cr alloyed layer was deposited onto the surface of Q235 low-carbon steel via double glow plasma surface metallurgy (DGPSM) to improve the steel's wear resistance. After the DGPSM treatment, the Fe-Al-Cr alloyed layer grown on the Q235 low-carbon steel was homogeneous and compact and had a thickness of 25 µm. The layer was found to be metallurgically adhered to the substrate. The frictional coefficient and specific wear rate of the sample with a Fe-Al-Cr alloyed layer (treated sample) were both lower than those of the bare substrate (untreated sample) at the measured temperatures (25, 250 and 450 °C). The results indicated that the substrate and the alloyed layer suffered oxidative wear and abrasive wear, respectively, and that the treated samples exhibited much better tribological properties than did the substrate. The formation of Fe2AlCr, Fe3Al(Cr), FeAl(Cr), Fe(Cr) sosoloid and Cr23C6 phases in the alloyed layer dramatically enhanced the wear resistance of the treated sample. In addition, the alloyed layer's oxidation film exhibited a self-healing capacity with lubrication action that also contributed to the improvement of the wear resistance at high temperature. In particular, at 450 °C, the specific wear rate of treated sample was 2.524 × 10-4 mm3/N m, which was only 45.2% of the untreated sample.

  1. Epithelium damage and protection during reopening of occluded airways in a physiologic microfluidic pulmonary airway model.

    PubMed

    Tavana, Hossein; Zamankhan, Parsa; Christensen, Paul J; Grotberg, James B; Takayama, Shuichi

    2011-08-01

    Airways of the peripheral lung are prone to closure at low lung volumes. Deficiency or dysfunction of pulmonary surfactant during various lung diseases compounds this event by destabilizing the liquid lining of small airways and giving rise to occluding liquid plugs in airways. Propagation of liquid plugs in airways during inflation of the lung exerts large mechanical forces on airway cells. We describe a microfluidic model of small airways of the lung that mimics airway architecture, recreates physiologic levels of pulmonary pressures, and allows studying cellular response to repeated liquid plug propagation events. Substantial cellular injury happens due to the propagation of liquid plugs devoid of surfactant. We show that addition of a physiologic concentration of a clinical surfactant, Survanta, to propagating liquid plugs protects the epithelium and significantly reduces cell death. Although the protective role of surfactants has been demonstrated in models of a propagating air finger in liquid-filled airways, this is the first time to study the protective role of surfactants in liquid plugs where fluid mechanical stresses are expected to be higher than in air fingers. Our parallel computational simulations revealed a significant decrease in mechanical forces in the presence of surfactant, confirming the experimental observations. The results support the practice of providing exogenous surfactant to patients in certain clinical settings as a protective mechanism against pathologic flows. More importantly, this platform provides a useful model to investigate various surface tension-mediated lung diseases at the cellular level. PMID:21487664

  2. Surface modification induced phase transformation and structure variation on the rapidly solidified recast layer of titanium

    SciTech Connect

    Tsai, Ming-Hung; Haung, Chiung-Fang; Shyu, Shih-Shiun; Chou, Yen-Ru; Lin, Ming-Hong; Peng, Pei-Wen; and others

    2015-08-15

    In this study, neodymium-doped yttrium orthovanadate (Nd:YVO{sub 4}) as a laser source with different scanning speeds was used on biomedical Ti surface. The microstructural and biological properties of laser-modified samples were investigated by means of optical microscope, electron microscope, X-ray diffraction, surface roughness instrument, contact angle and cell cytotoxicity assay. After laser modification, the rough volcano-like recast layer with micro-/nanoporous structure and wave-like recast layer with nanoporous structure were generated on the surfaces of laser-modified samples, respectively. It was also found out that, an α → (α + rutile-TiO{sub 2}) phase transition occurred on the recast layers of laser-modified samples. The Ti surface becomes hydrophilic at a high speed laser scanning. Moreover, the cell cytotoxicity assay demonstrated that laser-modified samples did not influence the cell adhesion and proliferation behaviors of osteoblast (MG-63) cell. The laser with 50 mm/s scanning speed induced formation of rough volcano-like recast layer accompanied with micro-/nanoporous structure, which can promote cell adhesion and proliferation of MG-63 cell on Ti surface. The results indicated that the laser treatment was a potential technology to enhance the biocompatibility for titanium. - Highlights: • Laser induced the formation of recast layer with micro-/nanoporous structure on Ti. • An α → (α + rutile-TiO{sub 2}) phase transition was observed within the recast layer. • The Ti surface becomes hydrophilic at a high speed laser scanning. • Laser-modified samples exhibit good biocompatibility to osteoblast (MG-63) cell.

  3. The surface location of individual residues in a bacterial S-layer protein.

    PubMed

    Kinns, Helen; Howorka, Stefan

    2008-03-21

    Bacterial surface layer (S-layer) proteins self-assemble into large two-dimensional crystalline lattices that form the outermost cell-wall component of all archaea and many eubacteria. Despite being a large class of self-assembling proteins, little is known about their molecular architecture. We investigated the S-layer protein SbsB from Geobacillus stearothermophilus PV72/p2 to identify residues located at the subunit-subunit interface and to determine the S-layer's topology. Twenty-three single cysteine mutants, which were previously mapped to the surface of the SbsB monomer, were subjected to a cross-linking screen using the photoactivatable, sulfhydryl-reactive reagent N-[4-(p-azidosalicylamido)butyl]-3'-(2'-pyridyldithio)propionamide. Gel electrophoretic analysis on the formation of cross-linked dimers indicated that 8 out of the 23 residues were located at the interface. In combination with surface accessibility data for the assembled protein, 10 residues were assigned to positions at the inner, cell-wall-facing lattice surface, while 5 residues were mapped to the outer, ambient-exposed lattice surface. In addition, the cross-linking screen identified six positions of intramolecular cross-linking within the assembled protein but not in the monomeric S-layer protein. Most likely, these intramolecular cross-links result from conformational changes upon self-assembly. The results are an important step toward the further structural elucidation of the S-layer protein via, for example, X-ray crystallography and cryo-electron microscopy. Our approach of identifying the surface location of residues is relevant to other planar supramolecular protein assemblies. PMID:18262545

  4. Optimizing pentacene thin-film transistor performance: Temperature and surface condition induced layer growth modification

    PubMed Central

    Lassnig, R.; Hollerer, M.; Striedinger, B.; Fian, A.; Stadlober, B.; Winkler, A.

    2015-01-01

    In this work we present in situ electrical and surface analytical, as well as ex situ atomic force microscopy (AFM) studies on temperature and surface condition induced pentacene layer growth modifications, leading to the selection of optimized deposition conditions and entailing performance improvements. We prepared p++-silicon/silicon dioxide bottom-gate, gold bottom-contact transistor samples and evaluated the pentacene layer growth for three different surface conditions (sputtered, sputtered + carbon and unsputtered + carbon) at sample temperatures during deposition of 200 K, 300 K and 350 K. The AFM investigations focused on the gold contacts, the silicon dioxide channel region and the highly critical transition area. Evaluations of coverage dependent saturation mobilities, threshold voltages and corresponding AFM analysis were able to confirm that the first 3–4 full monolayers contribute to the majority of charge transport within the channel region. At high temperatures and on sputtered surfaces uniform layer formation in the contact–channel transition area is limited by dewetting, leading to the formation of trenches and the partial development of double layer islands within the channel region instead of full wetting layers. By combining the advantages of an initial high temperature deposition (well-ordered islands in the channel) and a subsequent low temperature deposition (continuous film formation for low contact resistance) we were able to prepare very thin (8 ML) pentacene transistors of comparably high mobility. PMID:26543442

  5. SEM Analysis of MTAD Efficacy for Smear Layer Removal from Periodontally Affected Root Surfaces

    PubMed Central

    Houshmand, B.; Ghandi, M.; Nekoofar, MH.; Gholamii, Gh. A.; Tabor, R. K.; Dummer, P. M. H.

    2011-01-01

    Objective Biopure® MTAD (Dentsply Tulsa Dental, USA) has been developed as a final irrigant following root canal shaping to remove intracanal smear layer. Many of the unique properties of MTAD potentially transfer to the conditioning process of tooth roots during periodontal therapy. The aim of this ex vivo study was to evaluate the effect of MTAD on the removal of smear layer from root surfaces. Materials and Methods Thirty two longitudinally sectioned specimens from 16 freshly extracted teeth diagnosed with advanced periodontal disease were divided into four groups. In group 1 and 2, the root surfaces were scaled using Gracey curettes. In group 3 and 4, 0.5 mm of the root surface was removed using a fissure bur. The specimens in group 1 and 3 were then irrigated by normal saline. The specimens in groups 2 and 4 were irrigated with Biopure MTAD. All specimens were prepared for SEM and scored according to the presence of smear layer. Results MTAD significantly increased (P=0.001) the smear layer removal in both groups 2 and 4 compared to the associated control groups, in which only saline was used. Conclusion MTAD increased the removal of the smear layer from periodontally affected root surfaces. Use of MTAD as a periodontal conditioner may be suggested. PMID:22509454

  6. Impact of Bay-Breeze Circulations on Surface Air Quality and Boundary Layer Export

    NASA Technical Reports Server (NTRS)

    Loughner, Christopher P.; Tzortziou, Maria; Follette-Cook, Melanie; Pickering, Kenneth E.; Goldberg, Daniel; Satam, Chinmay; Weinheimer, Andrew; Crawford, James H.; Knapp, David J.; Montzka, Denise D.; Diskin, Glenn S.; Dickerson, Russell R.

    2014-01-01

    Meteorological and air-quality model simulations are analyzed alongside observations to investigate the role of the Chesapeake Bay breeze on surface air quality, pollutant transport, and boundary layer venting. A case study was conducted to understand why a particular day was the only one during an 11-day ship-based field campaign on which surface ozone was not elevated in concentration over the Chesapeake Bay relative to the closest upwind site and why high ozone concentrations were observed aloft by in situ aircraft observations. Results show that southerly winds during the overnight and early-morning hours prevented the advection of air pollutants from the Washington, D.C., and Baltimore, Maryland, metropolitan areas over the surface waters of the bay. A strong and prolonged bay breeze developed during the late morning and early afternoon along the western coastline of the bay. The strength and duration of the bay breeze allowed pollutants to converge, resulting in high concentrations locally near the bay-breeze front within the Baltimore metropolitan area, where they were then lofted to the top of the planetary boundary layer (PBL). Near the top of the PBL, these pollutants were horizontally advected to a region with lower PBL heights, resulting in pollution transport out of the boundary layer and into the free troposphere. This elevated layer of air pollution aloft was transported downwind into New England by early the following morning where it likely mixed down to the surface, affecting air quality as the boundary layer grew.

  7. Conquering the difficult airway.

    PubMed

    Gandy, William E

    2008-01-01

    Every medic should practice regularly for the inevitable difficult airway case. Practice should include review of the causes of difficult airways, as well as skill practice. Having a preassembled airway kit can make your response to an unexpected difficult situation easier. Of all the devices mentioned, the bougie is the airway practitioner's best friend. Using the BURP technique, if not contraindicated, together with the bougie will enable you to intubate many difficult patients with confidence. Remember, "If your patient cannot breathe, nothing else matters. PMID:18251307

  8. Covalent assembly of poly(ethyleneimine) via layer-by-layer deposition for enhancing surface density of protein and bacteria attachment

    NASA Astrophysics Data System (ADS)

    Xia, Bing; Shi, Jisen; Dong, Chen; Zhang, Wenyi; Lu, Ye; Guo, Ping

    2014-02-01

    Covalently assembly of low molecular weight poly(ethyleneimine) was introduced to glass surfaces via glutaraldehyde crosslinking, with focus on its application on protein immobilization or bacteria attachment. Characterizations of Fourier transform infrared spectroscopy and ellipsometry measurement revealed a stepwise growth of poly(ethyleneimine) films by layer-by-layer deposition. After fluorescein isothiocyanate labelling, photoluminescence spectroscopy measurement indicated that the amount of surface accessible amine groups had been gradually enhanced with increasing poly(ethyleneimine) layers deposition. As compared with traditional aminosilanized surfaces, the surface density of amine groups was enhanced by ∼11 times after five layers grafting, which resulted in ∼9-time increasing of surface density of immobilized bovine serum albumin. Finally, these as-prepared PEI multi-films with excellent biocompatibility were adopted as culture substrates to improve Escherichia coli adherence, which showed that their surface density had been increased by ∼251 times.

  9. 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...

  10. Surface modulation of complex stiffness via layer-by-layer assembly as a facile strategy for selective cell adhesion.

    PubMed

    Chang, Hao; Zhang, He; Hu, Mi; Chen, Xia-chao; Ren, Ke-feng; Wang, Jin-lei; Ji, Jian

    2015-02-01

    In-stent restenosis and thrombosis are the main severe problems that occur after the percutaneous vascular intervention. The competition between endothelial cells (ECs) and smooth muscle cells (SMCs) plays a key role during these pathological changes. The regulation of this competition offers new opportunities to design biomaterials in the cardiovascular fields. Bioactive molecules have been typically employed to increase EC adhesion and thereafter to enhance EC competitiveness; however, this method is associated with limitations from the point of view of practical and industrial applications. Herein, we present an approach to enhance EC competitiveness over that of SMC through the selective EC adhesion, which is achieved by modulating a complex surface stiffness based on the technique of layer-by-layer (LbL) assembly. This complex stiffness can be achieved by regulating the thickness of multilayer films coordinating with a rigid underlying substrate. The selective cell adhesion is attributed to changes in the complex surface stiffness and a different intrinsic property between ECs and SMCs. This study provides a facile and broadly applicable approach for the purpose of the enhancement of EC competitiveness over that of SMC, which has great potential for the development of cell-based functional biomaterials in the cardiovascular field. PMID:26218126

  11. Macro-carriers of plastic deformation of steel surface layers detected by digital image correlation

    NASA Astrophysics Data System (ADS)

    Kopanitsa, D. G.; Ustinov, A. M.; Potekaev, A. I.; Klopotov, A. A.; Kopanitsa, G. D.

    2016-01-01

    This paper presents a study of characteristics of an evolution of deformation fields in surface layers of medium-carbon low-alloy specimens under compression. The experiments were performed on the "Universal Testing Machine 4500" using a digital stereoscopic image processing system Vic-3D. A transition between stages is reflected as deformation redistribution on the near-surface layers. Electronic microscopy shows that the structure of the steel is a mixture of pearlite and ferrite grains. A proportion of pearlite is 40% and ferrite is 60%.

  12. Phase composition and structure of femtosecond laser-produced oxide layer on VT6 alloy surface

    NASA Astrophysics Data System (ADS)

    Kolobov, Yu R.; Zhidkov, M. V.; Golosov, E. V.; Vershinina, T. N.; Kudryashov, S. I.; Makarov, S. V.; Ionin, A. A.; Ligachev, A. E.

    2016-07-01

    The influence of femtosecond laser irradiation on the formation of an oxide layer on the surface of VT6 titanium alloy (Ti–6Al–4V) is studied. The structure, chemical and phase composition have been studied by x-ray diffraction, and scanning and transmission electron microscopy. The formation features of an oxide layer, which contains TiO2-rutile, TiO2-anatase Al2TiO5-aluminum titanate, Ti3O5-titanium oxide and TiO-titanium monoxide on the femtosecond laser-irradiation modified surface have been analyzed.

  13. Puzzling evidence for surface superconductivity in the layered dichalcogenide Cu10%TiSe2

    NASA Astrophysics Data System (ADS)

    Levy-Bertrand, F.; Michon, B.; Marcus, J.; Marcenat, C.; Kačmarčík, J.; Klein, T.; Cercellier, H.

    2016-04-01

    We report on specific heat and magnetotransport measurements performed on superconducting Cu10%TiSe2 single crystals. We show that superconductivity persists in transport measurements up to magnetic fields HR well above the upper critical field Hc2 deduced from the calorimetric measurements. Surprisingly this "surface" superconductivity is present for all magnetic field orientations, either parallel or perpendicular to the layers. For H‖ab, the temperature dependence of the HR/Hc2 ratio can be well reproduced by solving the Ginzburg-Landau equations in presence of a surface layer with reduced superconducting properties. Unexpectedly this temperature dependence does not depend on the field orientation.

  14. Modification of the surface layers of copper by a diffuse discharge in atmospheric pressure air

    NASA Astrophysics Data System (ADS)

    Shulepov, Mikhail A.; Erofeev, Mikhail V.; Oskomov, Konstantin V.; Tarasenko, Victor F.

    2015-12-01

    The paper presents the results of examination of copper samples exposed to a diffuse discharge initiated by a runaway electron beam in air under normal pressure. The changes in the chemical composition of the surface layers of copper caused by the action of the discharge were investigated. It has been found that the oxygen and carbon concentrations in the surface layers depend on the number of discharge pulses. The study was aimed at finding possible ways of using this type of discharge in research and industry.

  15. On the interaction of a vertical shear layer with a free surface

    NASA Astrophysics Data System (ADS)

    Dabiri, Dana

    2003-04-01

    New experiments have been conducted using a combined free-surface gradient detector (FSGD) and digital particle image velocimetry (DPIV) technique to study the interaction between a vertical shear layer, created by a surface-piercing splitter plate, and a free surface. The emphasis of this study is on understanding aspects of the interaction between the free-surface deformation (FSD) and the near-surface turbulence through the correlations between the elevation and the vorticity fields, and the spectral behaviour of the near-surface pressure. The Reynolds number of the present study, based on visual thickness and the velocity average of the two streams, is 12 100. Mean results for the velocity and vorticity fields show that self-similarity is achieved. Instantaneous data sets show that at the free surface, vortex tubes within the main rollers connect normally with the free surface as is evidenced by strong vorticity as well as the strong deformations at the free surface. The instantaneous data sets also show that the streamwise vortices near the braid regions, while weaker than those seen in the main rollers, also reconnect with the free surface. Statistical analyses show that the FSD is strongly correlated with the near-surface vorticity field, as the correlation coefficients are quite high (˜ 0.7-0.8). The pressure spectrum slope within the shear layer near the surface is found to be -10/3, compared with the analytically derived value of -11/3 (George et al. 1984) found for a shear layer in unbounded flow.

  16. Surface layer ozone and nitric oxides in the Arctic: The inuence of boundary layer dynamics, snowpack chemistry, surface exchanges, and seasonality

    NASA Astrophysics Data System (ADS)

    Van Dam, Brie A.

    The snowpack is a region of active chemistry. Aqueous chemistry in a quasi-liquid layer on snow grains and gas-phase chemical reactions in snow interstitial air can lead to the production or destruction of important trace gases. Physical transport parameters such as wind pumping and diffusion affect the vertical distribution of gases within the snowpack. The resulting emission or uptake of trace gases at the atmosphere-snowpack interface can have significant in uence on the chemistry of the lower atmosphere. In this work the dynamic interactions between the snowpack and atmosphere are examined from multiple perspectives. The primary focus is on ozone (O3) and nitrogen oxides (NOx) in the Arctic, a region undergoing widespread environmental change. To investigate an ice-sheet location with year round snow cover, data from a two-year campaign at Summit, Greenland are implemented. At Summit this study examines (1) the processes contributing to vigorous chemistry in snow interstitial air, and (2) the role of the boundary layer over snow in determining surface layer NOx. Physical and chemical processes are shown to contribute to distinct seasonal and diurnal cycles of O3, NO, and NO2 in the snowpack. Boundary layer depths estimated from sonic anemometer turbulence quantities are used alongside sodar-derived values to show that the depth of the stable to weakly stable boundary layer at Summit was not a primary factor in determining NO x in early summer. Motivated by observations of an increase in the length of the snow-free season in the Arctic in recent decades, data from a one-year experiment at the seasonally-snow covered location of Toolik Lake, AK are also incorporated. This study shows the first observations of springtime ozone depletion events at a location over 200 km from the coast in the Arctic. FLEXPART analysis is used to illustrate that these inland events are linked to transport conditions. Lastly at this location, eddy-covariance O3 uxes were calculated to

  17. Layer-by-layer TiO(2)/WO(3) thin films as efficient photocatalytic self-cleaning surfaces.

    PubMed

    Patrocinio, Antonio Otavio T; Paula, Leonardo F; Paniago, Roberto M; Freitag, Janna; Bahnemann, Detlef W

    2014-10-01

    New TiO2/WO3 films were produced by the layer-by-layer (LbL) technique and successfully applied as self-cleaning photocatalytic surfaces. The films were deposited on fluorine doped tin oxide (FTO) glass substrates from the respective metal oxide nanoparticles obtained by the sol-gel method. Thirty alternative immersions in pH = 2 TiO2 and pH = 10 WO3 sols resulted in ca. 400 nm thick films that exhibited a W(VI)/Ti(IV) molar ratio of 0.5, as determined by X-ray photoelectron spectroscopy. Scanning electron microscopy, along with atomic force images, showed that the resulting layers are constituted by aggregates of very small nanoparticles (<20 nm) and exhibited nanoporous and homogeneous morphology. The electronic and optical properties of the films were investigated by UV-vis spectrophotometry and ultraviolet photoelectron spectroscopy. The films behave as nanoscale heterojunctions, and the presence of WO3 nanoparticles caused a decrease in the optical band gap of the bilayers compared to that of pure LbL TiO2 films. The TiO2/WO3 thin films exhibited high hydrophilicity, which is enhanced after exposition to UV light, and they can efficiently oxidize gaseous acetaldehyde under UV(A) irradiation. Photonic efficiencies of ξ = 1.5% were determined for films constituted by 30 TiO2/WO3 bilayers in the presence of 1 ppm of acetaldehyde, which are ∼2 times higher than those observed for pure LbL TiO2 films. Therefore, these films can act as efficient and cost-effective layers for self-cleaning, antifogging applications. PMID:25216058

  18. Role of platelets in allergic airway inflammation.

    PubMed

    Idzko, Marco; Pitchford, Simon; Page, Clive

    2015-06-01

    Increasing evidence suggests an important role for platelets and their products (e.g., platelet factor 4, β-thromboglobulin, RANTES, thromboxane, or serotonin) in the pathogenesis of allergic diseases. A variety of changes in platelet function have been observed in patients with asthma, such as alterations in platelet secretion, expression of surface molecules, aggregation, and adhesion. Moreover, platelets have been found to actively contribute to most of the characteristic features of asthma, including bronchial hyperresponsiveness, bronchoconstriction, airway inflammation, and airway remodeling. This review brings together the current available data from both experimental and clinical studies that have investigated the role of platelets in allergic airway inflammation and asthma. It is anticipated that a better understanding of the role of platelets in the pathogenesis of asthma might lead to novel promising therapeutic approaches in the treatment of allergic airway diseases. PMID:26051948

  19. Observations and proxies of the surface layer throughflow in Lombok Strait

    NASA Astrophysics Data System (ADS)

    Susanto, R. Dwi; Gordon, Arnold L.; Sprintall, Janet

    2007-03-01

    Seasonal to interannual variability of the Lombok Strait surface layer transport is investigated. The geostrophic transport within the surface layer is estimated from the cross-channel pressure gradient measured by a pair of shallow pressure gauges positioned on opposing sides of Lombok Strait during 1996-1999. The Ekman transport through Lombok Strait, derived from scatterometer winds, is less than 10% or ˜0.15 Sv of the estimated surface layer geostrophic transport. Monsoonal forcing is clearly evident in the regional sea surface height anomalies (SSHA) as derived from the satellite altimeter measurements. During the southeast monsoon, relatively low sea level is observed to the south of Lombok Strait, with relatively high sea level to the north; conditions reverse during the northwest monsoon. Estimated transports from the cross-channel pressure gradient, winds, SSHA and thermocline depth anomalies all reveal interannual variability associated with ENSO. Both the thermocline depth anomaly and the SSHA to the south of the East Java coast correlate significantly (r = 0.7) with the Lombok Strait total surface layer throughflow. The difference of SSHA from the south of the East Java coast minus the SSHA north of Lombok shows a higher correlation (r = 0.84). These high correlation values suggest that SSHA and thermocline depth anomalies can be used as proxies for the Lombok Strait surface layer throughflow. Qualitatively, such proxy transports agree with the surface transport inferred from the pressure gauges and Ekman transport in Lombok Strait from 1996 to 1999, and also with direct velocity measurements from current meter data obtained in 1985 and 2004-2005.

  20. Improvement and protection of niobium surface superconductivity by atomic layer deposition and heat treatment

    SciTech Connect

    Proslier, T.; Zasadzinski, J.; Moore, J.; Pellin, M.; Elam, J.; Cooley, L.; Antoine, C.; /Saclay

    2008-11-01

    A method to treat the surface of Nb is described, which potentially can improve the performance of superconducting rf cavities. We present tunneling and x-ray photoemission spectroscopy measurements at the surface of cavity-grade niobium samples coated with a 3 nm alumina overlayer deposited by atomic layer deposition. The coated samples baked in ultrahigh vacuum at low temperature degraded superconducting surface. However, at temperatures above 450 C, the tunneling conductance curves show significant improvements in the superconducting density of states compared with untreated surfaces.

  1. Surface-layer response over shrub-steppe canopy during springtime

    SciTech Connect

    Hubbe, J.M.; Kirkham, R.R.; Downs, J.L.; Shaw, W.J.

    1994-03-01

    The exchange of energy and trace gases between the atmosphere and heterogeneous surfaces is gaining increasing attention in the scientific community. An observational study of surface energetics and atmospheric response was undertaken in 1992 to provide data for model application to semi-arid climates and for the evaluation of various models. The objectives of this field study were to quantify surface-layer fluxes over a mixed canopy in a semi-arid climate, to quantify canopy and soil energetics during the transition from moist winter conditions to dry summer conditions, and to investigate parameterization of surface exchange processes in a mixed canopy setting.

  2. Ozone depletion events observed in the high latitude surface layer during the TOPSE aircraft program

    NASA Astrophysics Data System (ADS)

    Ridley, B. A.; Atlas, E. L.; Montzka, D. D.; Browell, E. V.; Cantrell, C. A.; Blake, D. R.; Blake, N. J.; Cinquini, L.; Coffey, M. T.; Emmons, L. K.; Cohen, R. C.; Deyoung, R. J.; Dibb, J. E.; Eisele, F. L.; Flocke, F. M.; Fried, A.; Grahek, F. E.; Grant, W. B.; Hair, J. W.; Hannigan, J. W.; Heikes, B. J.; Lefer, B. L.; Mauldin, R. L.; Moody, J. L.; Shetter, R. E.; Snow, J. A.; Talbot, R. W.; Thornton, J. A.; Walega, J. G.; Weinheimer, A. J.; Wert, B. P.; Wimmers, A. J.

    2003-02-01

    During the Tropospheric Ozone Production about the Spring Equinox (TOPSE) aircraft program, ozone depletion events (ODEs) in the high latitude surface layer were investigated using lidar and in situ instruments. Flight legs of 100 km or longer distance were flown 32 times at 30 m altitude over a variety of regions north of 58° between early February and late May 2000. ODEs were found on each flight over the Arctic Ocean but their occurrence was rare at more southern latitudes. However, large area events with depletion to over 2 km altitude in one case were found as far south as Baffin Bay and Hudson Bay and as late as 22 May. There is good evidence that these more southern events did not form in situ but were the result of export of ozone-depleted air from the surface layer of the Arctic Ocean. Surprisingly, relatively intact transport of ODEs occurred over distances of 900-2000 km and in some cases over rough terrain. Accumulation of constituents in the frozen surface over the dark winter period cannot be a strong prerequisite of ozone depletion since latitudes south of the Arctic Ocean would also experience a long dark period. Some process unique to the Arctic Ocean surface or its coastal regions remains unidentified for the release of ozone-depleting halogens. There was no correspondence between coarse surface features such as solid ice/snow, open leads, or polynyas with the occurrence of or intensity of ozone depletion over the Arctic or subarctic regions. Depletion events also occurred in the absence of long-range transport of relatively fresh "pollution" within the high latitude surface layer, at least in spring 2000. Direct measurements of halogen radicals were not made. However, the flights do provide detailed information on the vertical structure of the surface layer and, during the constant 30 m altitude legs, measurements of a variety of constituents including hydroxyl and peroxy radicals. A summary of the behavior of these constituents is made. The

  3. Effects of the Thickness of Niobium Surface Oxide Layers on Field Emission

    SciTech Connect

    A.T. Wu, S. Jin, J.D. Mammosser, R.A. Rimmer, X.Y. Lu, K. Zhao

    2011-09-01

    Field emission on the inner surfaces of niobium superconducting radio frequency cavities is still one of the major obstacles for reaching high accelerating gradients for SRF community. Our previous experimental results* seemed to imply that the threshold of field emission was related to the thickness of Nb surface oxide layers. In this contribution, a more detailed study on the influences of the surface oxide layers on the field emission on Nb surfaces will be reported. By anodization technique, the thickness of the surface pentoxide layer was artificially fabricated from 3 nm up to 460 nm. A home-made scanning field emission microscope was employed to perform the scans on the surfaces. Emitters were characterized using a scanning electron microscope together with an energy dispersive x-ray analyzer. The SFEM experimental results were analyzed in terms of surface morphology and oxide thickness of Nb samples and chemical composition and geographic shape of the emitters. A model based on the classic electromagnetic theory was developed trying to understand the experimental results. Possibly implications for Nb SRF cavity applications from this study will be discussed.

  4. Crossover between silicene and ultra-thin Si atomic layers on Ag(111) surfaces

    NASA Astrophysics Data System (ADS)

    Guo, Zhi-Xin; Oshiyama, Atsushi

    2015-04-01

    We report on total-energy electronic structure calculations in the density-functional theory performed for the ultra-thin atomic layers of Si on Ag(111) surfaces. We find several distinct stable silicene structures: \\sqrt{3}× \\sqrt{3}, 3 × 3, \\sqrt{7}× \\sqrt{7} with the thickness of Si increasing from monolayer to quad-layer. The structural bistability and tristability of the multilayer silicene structures on Ag surfaces are obtained, where the calculated transition barriers infer the occurrence of the flip-flop motion at low temperature. The calculated scanning tunneling microscope (STM) images agree well with the experimental observations. We also find the stable existence of 2 × 1 π-bonded chain and 7 × 7 dimer-adatom-stacking fault Si(111)-surface structures on Ag(111), which clearly shows the crossover of silicene-silicon structures for the multilayer Si on Ag surfaces. We further find the absence of the Dirac states for multilayer silicene on Ag(111) due to the covalent interactions of the silicene-Ag interface and Si-Si interlayer. Instead, we find a new state near the Fermi level composed of π orbitals located on the surface layer of \\sqrt{3}× \\sqrt{3} multilayer silicene, which satisfies the hexagonal symmetry and exhibits the linear energy dispersion. By examining the electronic properties of 2 × 1 π-bonded chain structures, we find that the surface-related π states of multilayer Si structures are robust on Ag surfaces.

  5. Surfactant-associated bacteria in the near-surface layer of the ocean.

    PubMed

    Kurata, Naoko; Vella, Kate; Hamilton, Bryan; Shivji, Mahmood; Soloviev, Alexander; Matt, Silvia; Tartar, Aurélien; Perrie, William

    2016-01-01

    Certain marine bacteria found in the near-surface layer of the ocean are expected to play important roles in the production and decay of surface active materials; however, the details of these processes are still unclear. Here we provide evidence supporting connection between the presence of surfactant-associated bacteria in the near-surface layer of the ocean, slicks on the sea surface, and a distinctive feature in the synthetic aperture radar (SAR) imagery of the sea surface. From DNA analyses of the in situ samples using pyrosequencing technology, we found the highest abundance of surfactant-associated bacterial taxa in the near-surface layer below the slick. Our study suggests that production of surfactants by marine bacteria takes place in the organic-rich areas of the water column. Produced surfactants can then be transported to the sea surface and form slicks when certain physical conditions are met. This finding has potential applications in monitoring organic materials in the water column using remote sensing techniques. Identifying a connection between marine bacteria and production of natural surfactants may provide a better understanding of the global picture of biophysical processes at the boundary between the ocean and atmosphere, air-sea exchange of greenhouse gases, and production of climate-active marine aerosols. PMID:26753514

  6. Surfactant-associated bacteria in the near-surface layer of the ocean

    PubMed Central

    Kurata, Naoko; Vella, Kate; Hamilton, Bryan; Shivji, Mahmood; Soloviev, Alexander; Matt, Silvia; Tartar, Aurélien; Perrie, William

    2016-01-01

    Certain marine bacteria found in the near-surface layer of the ocean are expected to play important roles in the production and decay of surface active materials; however, the details of these processes are still unclear. Here we provide evidence supporting connection between the presence of surfactant-associated bacteria in the near-surface layer of the ocean, slicks on the sea surface, and a distinctive feature in the synthetic aperture radar (SAR) imagery of the sea surface. From DNA analyses of the in situ samples using pyrosequencing technology, we found the highest abundance of surfactant-associated bacterial taxa in the near-surface layer below the slick. Our study suggests that production of surfactants by marine bacteria takes place in the organic-rich areas of the water column. Produced surfactants can then be transported to the sea surface and form slicks when certain physical conditions are met. This finding has potential applications in monitoring organic materials in the water column using remote sensing techniques. Identifying a connection between marine bacteria and production of natural surfactants may provide a better understanding of the global picture of biophysical processes at the boundary between the ocean and atmosphere, air-sea exchange of greenhouse gases, and production of climate-active marine aerosols. PMID:26753514

  7. Experimental data and model for the turbulent boundary layer on a convex, curved surface

    NASA Technical Reports Server (NTRS)

    Gillis, J. C.; Johnson, J. P.; Moffat, R. J.; Kays, W. M.

    1981-01-01

    Experiments were performed to determine how boundary layer turbulence is affected by strong convex curvature. The data gathered on the behavior of the Reynolds stress suggested the formulation of a simple turbulence model. Data were taken on two separate facilities. Both rigs had flow from a flat surface, over a convex surface with 90 deg of turning and then onto a flat recovery surface. The geometry was adjusted so that, for both rigs, the pressure gradient along the test surface was zero. Two experiments were performed at delta/R approximately 0.10, and one at weaker curvature with delta/R approximately 0.05. Results show that after a sudden introduction of curvature the shear stress in the outer part of the boundary layer is sharply diminished and is even slightly negative near the edge. The wall shear also drops off quickly downstream. When the surface suddenly becomes flat again, the wall shear and shear stress profiles recover very slowly towards flat wall conditions. A simple turbulence model, which was based on the theory that the Prandtl mixing length in the outer layer should scale on the velocity gradient layer, was shown to account for the slow recovery.

  8. Critical heat flux maxima resulting from the controlled morphology of nanoporous hydrophilic surface layers

    NASA Astrophysics Data System (ADS)

    Tetreault-Friend, Melanie; Azizian, Reza; Bucci, Matteo; McKrell, Thomas; Buongiorno, Jacopo; Rubner, Michael; Cohen, Robert

    2016-06-01

    Porous hydrophilic surfaces have been shown to enhance the critical heat flux (CHF) in boiling heat transfer. In this work, the separate effects of pore size and porous layer thickness on the CHF of saturated water at atmospheric pressure were experimentally investigated using carefully engineered surfaces. It was shown that, for a fixed pore diameter (˜20 nm), there is an optimum layer thickness (˜2 μm), for which the CHF value is maximum, corresponding to ˜115% enhancement over the value for uncoated surfaces. Similarly, a maximum CHF value (˜100% above the uncoated surface CHF) was observed while changing the pore size at a constant layer thickness (˜1 μm). To explain these CHF maxima, we propose a mechanistic model that can capture the effect of pore size and pore thickness on CHF. The good agreement found between the model and experimental data supports the hypothesis that CHF is governed by the competition between capillary wicking, viscous pressure drop and evaporation, as well as conduction heat transfer within the porous layer. The model can be used to guide the development of engineered surfaces with superior boiling performance.

  9. Polarization-Conversion Guided Mode (PCGM) technique for exploring thin anisotropic surface layers.

    PubMed

    Yang, Fuzi; Ruan, Lizhen; Sambles, John R

    2007-09-01

    A Polarization-Conversion Guided Mode (PCGM) technique has been developed to quantify optical anisotropy as low as 10-5 for a surface layer only 10 nm thick. The optical geometry consists of an index-fluid matched prism-coupler and an air-gap waveguide comprising the thin sample on a glass plate as the incident surface with a gold reflector forming the other surface of the guide. This allows non-destructive characterization of the optical anisotropy of surface layers. The polarization conversion signal is extraordinarily sensitive. Thus the influence of the polarization purity of the incoming beam, very small twists and/or tilts between the normal to the prism bottom surface and the sample plane, have all been analyzed in detail to allow extraction of the sought for information about the thin layer. Rubbed polyimide thin films and incline-evaporated SiOx layers, both used for liquid crystal alignment, have been examined by this PCGM technique to demonstrate its power. PMID:19547479

  10. Gallium nitride surface protection during RTA annealing with a GaOxNy cap-layer

    NASA Astrophysics Data System (ADS)

    Khalfaoui, Wahid; Oheix, T.; Cayrel, F.; Benoit, R.; Yvon, A.; Collard, E.; Alquier, D.

    2016-04-01

    Gallium nitride (GaN) is generally considered a good candidate for power electronic devices such as Schottky barrier diodes (SBDs). Nevertheless, GaN has a strong sensitivity to high temperature treatments and a cap-layer is mandatory to protect the material surface during annealing at high temperature such as post-implantation treatments. In this work, an oxidized gallium nitride layer (GaOxNy) was generated with Oxford PECVD equipment using a N2O plasma treatment to protect the GaN surface during a rapid thermal annealing (RTA), in the range of 1000 °C-1150 °C for a few minutes. Before annealing, c-TLM patterns were processed on the GaOxNy/GaN sample to characterize its sheet resistance. After the N2O plasma treatment, the sample exhibited lower sheet resistance, indicating a better n-type conduction of the GaOxNy layer due to an excess of free carriers, compared to the as-grown GaN layer. The GaOxNy/GaN surface was then annealed at 1150 °C for 3 min and observed through AFM imaging. The surface exhibited a good quality with a low roughness, nevertheless, a low density of small hexagonal pits appeared after annealing. Finally, studies to determine an efficient etching process of the GaOxNy cap-layer were conducted using both chemical and physical approaches. We observed that efficient etching of the layer was achieved using a heated hydrofluoridric acid (HF 25%) solution. To conclude, GaOxNy has proved to be an efficient cap-layer for GaN protection at high temperature.

  11. Shear rheology of mixed protein adsorption layers vs their structure studied by surface force measurements.

    PubMed

    Danov, Krassimir D; Kralchevsky, Peter A; Radulova, Gergana M; Basheva, Elka S; Stoyanov, Simeon D; Pelan, Eddie G

    2015-08-01

    The hydrophobins are proteins that form the most rigid adsorption layers at liquid interfaces in comparison with all other investigated proteins. The mixing of hydrophobin HFBII with other conventional proteins is expected to reduce the surface shear elasticity and viscosity, E(sh) and η(sh), proportional to the fraction of the conventional protein. However, the experiments show that the effect of mixing can be rather different depending on the nature of the additive. If the additive is a globular protein, like β-lactoglobulin and ovalbumin, the surface rigidity is preserved, and even enhanced. The experiments with separate foam films indicate that this is due to the formation of a bilayer structure at the air/water interface. The more hydrophobic HFBII forms the upper layer adjacent to the air phase, whereas the conventional globular protein forms the lower layer that faces the water phase. Thus, the elastic network formed by the adsorbed hydrophobin remains intact, and even reinforced by the adjacent layer of globular protein. In contrast, the addition of the disordered protein β-casein leads to softening of the HFBII adsorption layer. Similar (an even stronger) effect is produced by the nonionic surfactant Tween 20. This can be explained with the penetration of the hydrophobic tails of β-casein and Tween 20 between the HFBII molecules at the interface, which breaks the integrity of the hydrophobin interfacial elastic network. The analyzed experimental data for the surface shear rheology of various protein adsorption layers comply with a viscoelastic thixotropic model, which allows one to determine E(sh) and η(sh) from the measured storage and loss moduli, G' and G″. The results could contribute for quantitative characterization and deeper understanding of the factors that control the surface rigidity of protein adsorption layers with potential application for the creation of stable foams and emulsions with fine bubbles or droplets. PMID:24828304

  12. A Novel Surface Structure Consisting of Contact-active Antibacterial Upper-layer and Antifouling Sub-layer Derived from Gemini Quaternary Ammonium Salt Polyurethanes.

    PubMed

    He, Wei; Zhang, Yi; Li, Jiehua; Gao, Yunlong; Luo, Feng; Tan, Hong; Wang, Kunjie; Fu, Qiang

    2016-01-01

    Contact-active antibacterial surfaces play a vital role in preventing bacterial contamination of artificial surfaces. In the past, numerous researches have been focused on antibacterial surfaces comprising of antifouling upper-layer and antibacterial sub-layer. In this work, we demonstrate a reversed surface structure which integrate antibacterial upper-layer and antifouling sub-layer. These surfaces are prepared by simply casting gemini quaternary ammonium salt waterborne polyurethanes (GWPU) and their blends. Due to the high interfacial energy of gemini quaternary ammonium salt (GQAS), chain segments containing GQAS can accumulate at polymer/air interface to form an antibacterial upper-layer spontaneously during the film formation. Meanwhile, the soft segments composed of polyethylene glycol (PEG) formed the antifouling sub-layer. Our findings indicate that the combination of antibacterial upper-layer and antifouling sub-layer endow these surfaces strong, long-lasting antifouling and contact-active antibacterial properties, with a more than 99.99% killing efficiency against both gram-positive and gram-negative bacteria attached to them. PMID:27561546

  13. A Novel Surface Structure Consisting of Contact-active Antibacterial Upper-layer and Antifouling Sub-layer Derived from Gemini Quaternary Ammonium Salt Polyurethanes

    PubMed Central

    He, Wei; Zhang, Yi; Li, Jiehua; Gao, Yunlong; Luo, Feng; Tan, Hong; Wang, Kunjie; Fu, Qiang

    2016-01-01

    Contact-active antibacterial surfaces play a vital role in preventing bacterial contamination of artificial surfaces. In the past, numerous researches have been focused on antibacterial surfaces comprising of antifouling upper-layer and antibacterial sub-layer. In this work, we demonstrate a reversed surface structure which integrate antibacterial upper-layer and antifouling sub-layer. These surfaces are prepared by simply casting gemini quaternary ammonium salt waterborne polyurethanes (GWPU) and their blends. Due to the high interfacial energy of gemini quaternary ammonium salt (GQAS), chain segments containing GQAS can accumulate at polymer/air interface to form an antibacterial upper-layer spontaneously during the film formation. Meanwhile, the soft segments composed of polyethylene glycol (PEG) formed the antifouling sub-layer. Our findings indicate that the combination of antibacterial upper-layer and antifouling sub-layer endow these surfaces strong, long-lasting antifouling and contact-active antibacterial properties, with a more than 99.99% killing efficiency against both gram-positive and gram-negative bacteria attached to them. PMID:27561546

  14. In vivo measurement of skin surface strain and sub-surface layer deformation induced by natural tissue stretching.

    PubMed

    Maiti, Raman; Gerhardt, Lutz-Christian; Lee, Zing S; Byers, Robert A; Woods, Daniel; Sanz-Herrera, José A; Franklin, Steve E; Lewis, Roger; Matcher, Stephen J; Carré, Matthew J

    2016-09-01

    Stratum corneum and epidermal layers change in terms of thickness and roughness with gender, age and anatomical site. Knowledge of the mechanical and tribological properties of skin associated with these structural changes are needed to aid in the design of exoskeletons, prostheses, orthotics, body mounted sensors used for kinematics measurements and in optimum use of wearable on-body devices. In this case study, optical coherence tomography (OCT) and digital image correlation (DIC) were combined to determine skin surface strain and sub-surface deformation behaviour of the volar forearm due to natural tissue stretching. The thickness of the epidermis together with geometry changes of the dermal-epidermal junction boundary were calculated during change in the arm angle, from flexion (90°) to full extension (180°). This posture change caused an increase in skin surface Lagrange strain, typically by 25% which induced considerable morphological changes in the upper skin layers evidenced by reduction of epidermal layer thickness (20%), flattening of the dermal-epidermal junction undulation (45-50% reduction of flatness being expressed as Ra and Rz roughness profile height change) and reduction of skin surface roughness Ra and Rz (40-50%). The newly developed method, DIC combined with OCT imaging, is a powerful, fast and non-invasive methodology to study structural skin changes in real time and the tissue response provoked by mechanical loading or stretching. PMID:27310571

  15. Spectroscopic study on uranyl carboxylate complexes formed at the surface layer of Sulfolobus acidocaldarius.

    PubMed

    Reitz, Thomas; Rossberg, Andre; Barkleit, Astrid; Steudtner, Robin; Selenska-Pobell, Sonja; Merroun, Mohamed L

    2015-02-14

    The complexation of U(vi) at the proteinaceous surface layer (S-layer) of the archaeal strain Sulfolobus acidocaldarius was investigated over a pH range from pH 1.5 to 6 at the molecular scale using time-resolved laser-induced fluorescence spectroscopy (TRLFS) and U L(III)-edge extended X-ray absorption fine structure (EXAFS). The S-layer, which represents the interface between the cell and its environment, is very stable against high temperatures, proteases, and detergents. This allowed the isolation and purification of S-layer ghosts (= empty cells) that maintain the size and shape of the cells. In contrast to many other microbial cell envelope compounds the studied S-layer is not phosphorylated, enabling the investigation of uranyl carboxylate complexes formed at microbial surfaces. The latter are usually masked by preferentially formed uranyl phosphate complexes. We demonstrated that at highly acidic conditions (pH 1.5 to 3) no uranium was bound by the S-layer. In contrast to that, at moderate acidic pH conditions (pH 4.5 and 6) a complexation of U(vi) at the S-layer via deprotonated carboxylic groups was stimulated. Titration studies revealed dissociation constants for the carboxylic groups of glutamic and aspartic acid residues of pK(a) = 4.78 and 6.31. The uranyl carboxylate complexes formed at the S-layer did not show luminescence properties at room temperature, but only under cryogenic conditions. The obtained luminescence maxima are similar to those of uranyl acetate. EXAFS spectroscopy demonstrated that U(vi) in these complexes is mainly coordinated to carboxylate groups in a bidentate binding mode. The elucidation of the molecular structure of these complexes was facilitated by the absence of phosphate groups in the studied S-layer protein. PMID:25387060

  16. Analysis of corrosion layers in ancient Roman silver coins with high resolution surface spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Keturakis, Christopher J.; Notis, Ben; Blenheim, Alex; Miller, Alfred C.; Pafchek, Rob; Notis, Michael R.; Wachs, Israel E.

    2016-07-01

    Determination of the microchemistry of surface corrosion layers on ancient silver alloy coins is important both in terms of understanding the nature of archaeological environmental conditions to which these ancient coins were exposed and also to help in their conservation. In this present study, five ancient silver alloy coins (225 BCE-244 CE) were used as test vehicles to measure their immediate surface microchemistry and evaluate the appropriateness and limitations of High Sensitivity-Low Energy Ion Scattering Spectroscopy (HS-LEIS, 0.3 nm depth analysis), High Resolution-X-ray Photoelectron Spectroscopy (HR-XPS, 1-3 nm depth analysis) and High Resolution-Raman Spectroscopy (HR-Raman, ∼1000 nm depth analysis). Additional information about the deeper corrosion layers, up to ∼300-1000 nm, was provided by dynamic HS-LEIS and HR-Raman spectroscopy. While not archeologically significant, the use of these coins of small commercial value provides data that is more representative of the weaker signals typically obtained from ancient corroded objects, which can be in stark contrast to pristine data often obtained from carefully prepared alloys of known composition. The oldest coins, from 225 to 214 BCE, possessed an outermost surface layer containing Cu2O, Na, Al, Pb, and adsorbed hydrocarbons, while the more recent coins, from 98 to 244 CE, contained Cu2O, Ag, N, F, Na, Al, S, Cl, and adsorbed hydrocarbons in similar corresponding surface layers. It thus appears that alloying with copper, even in small amounts, leads to the formation of an outer Cu2O layer. Depth profiling revealed the presence of K, Na, Cl, and S as key corrosion components for both sets of coins with S, most likely as Ag2S, concentrated towards the surface while the Cl, most likely as AgCl, penetrated deeper. Schema to understand the overall chemistry of the corrosion layers present on these silver alloy coins were developed from the equipment limitations encountered and are presented.

  17. An Optimal Estimation Method to Obtain Surface Layer Turbulent Fluxes from Profile Measurements

    NASA Astrophysics Data System (ADS)

    Kang, D.

    2015-12-01

    In the absence of direct turbulence measurements, the turbulence characteristics of the atmospheric surface layer are often derived from measurements of the surface layer mean properties based on Monin-Obukhov Similarity Theory (MOST). This approach requires two levels of the ensemble mean wind, temperature, and water vapor, from which the fluxes of momentum, sensible heat, and water vapor can be obtained. When only one measurement level is available, the roughness heights and the assumed properties of the corresponding variables at the respective roughness heights are used. In practice, the temporal mean with large number of samples are used in place of the ensemble mean. However, in many situations the samples of data are taken from multiple levels. It is thus desirable to derive the boundary layer flux properties using all measurements. In this study, we used an optimal estimation approach to derive surface layer properties based on all available measurements. This approach assumes that the samples are taken from a population whose ensemble mean profile follows the MOST. An optimized estimate is obtained when the results yield a minimum cost function defined as a weighted summation of all error variance at each sample altitude. The weights are based one sample data variance and the altitude of the measurements. This method was applied to measurements in the marine atmospheric surface layer from a small boat using radiosonde on a tethered balloon where temperature and relative humidity profiles in the lowest 50 m were made repeatedly in about 30 minutes. We will present the resultant fluxes and the derived MOST mean profiles using different sets of measurements. The advantage of this method over the 'traditional' methods will be illustrated. Some limitations of this optimization method will also be discussed. Its application to quantify the effects of marine surface layer environment on radar and communication signal propagation will be shown as well.

  18. Deformation characteristics of the near-surface layers of zirconia ceramics implanted with aluminum ions

    NASA Astrophysics Data System (ADS)

    Ghyngazov, S. A.; Vasiliev, I. P.; Frangulyan, T. S.; Chernyavski, A. V.

    2015-10-01

    The effect of ion treatment on the phase composition and mechanical properties of the near-surface layers of zirconium ceramic composition 97 ZrO2-3Y2O3 (mol%) was studied. Irradiation of the samples was carried out by accelerated ions of aluminum with using vacuum-arc source Mevva 5-Ru. Ion beam had the following parameters: the energy of the accelerated ions E = 78 keV, the pulse current density Ji = 4mA / cm2, current pulse duration equal τ = 250 mcs, pulse repetition frequency f = 5 Hz. Exposure doses (fluence) were 1016 и 1017 ion/cm2. The depth distribution implanted ions was studied by SIMS method. It is shown that the maximum projected range of the implanted ions is equal to 250 nm. Near-surface layers were investigated by X-ray diffraction (XRD) at fixed glancing incidence angle. It is shown that implantation of aluminum ions into the ceramics does not lead to a change in the phase composition of the near-surface layer. The influence of implanted ions on mechanical properties of ceramic near-surface layers was studied by the method of dynamic nanoindentation using small loads on the indenter P=300 mN. It is shown that in ion- implanted ceramic layer the processes of material recovery in the deformed region in the unloading mode proceeds with higher efficiency as compared with the initial material state. The deformation characteristics of samples before and after ion treatment have been determined from interpretation of the resulting P-h curves within the loading and unloading sections by the technique proposed by Oliver and Pharr. It was found that implantation of aluminum ions in the near-surface layer of zirconia ceramics increases nanohardness and reduces the Young's modulus.

  19. Surface morphology and Raman spectroscopy of thin layers of antimony and bismuth chalcogenides

    NASA Astrophysics Data System (ADS)

    Luk'yanova, L. N.; Bibik, A. Yu.; Aseev, V. A.; Usov, O. A.; Makarenko, I. V.; Petrov, V. N.; Nikonorov, N. V.; Kutasov, V. A.

    2016-07-01

    The phonon spectra in thin layers of bismuth telluride and solid solutions of Bi2- x Sb x Te3- y Se y of different composition, belonging to three-dimensional topological insulators, have been investigated by micro-Raman spectroscopy, and the morphology of an interlayer van der Waals (0001) surface in them has been studied by semicontact atomic force microscopy at room temperature. The analysis of the Raman spectra and the intensity ratio of active and inactive longitudinal optical modes depending on the composition, morphology of the interlayer surface, and thickness of the layers enabled the estimation of the effect of topological surface states of Dirac fermions, associated with the strengthening of the electron-phonon interaction as a result of resonance Raman scattering, and the identification of the compositions, in which the contribution of topological surface states becomes dominant.

  20. Overexpression of Smad2 Drives House Dust Mite–mediated Airway Remodeling and Airway Hyperresponsiveness via Activin and IL-25

    PubMed Central

    Gregory, Lisa G.; Mathie, Sara A.; Walker, Simone A.; Pegorier, Sophie; Jones, Carla P.; Lloyd, Clare M.

    2010-01-01

    Rationale: Airway hyperreactivity and remodeling are characteristic features of asthma. Interactions between the airway epithelium and environmental allergens are believed to be important in driving development of pathology, particularly because altered epithelial gene expression is common in individuals with asthma. Objectives: To investigate the interactions between a modified airway epithelium and a common aeroallergen in vivo. Methods: We used an adenoviral vector to generate mice overexpressing the transforming growth factor-β signaling molecule, Smad2, in the airway epithelium and exposed them to house dust mite (HDM) extract intranasally. Measurements and Main Results: Smad2 overexpression resulted in enhanced airway hyperreactivity after allergen challenge concomitant with changes in airway remodeling. Subepithelial collagen deposition was increased and smooth muscle hyperplasia was evident resulting in thickening of the airway smooth muscle layer. However, there was no increase in airway inflammation in mice given the Smad2 vector compared with the control vector. Enhanced airway hyperreactivity and remodeling did not correlate with elevated levels of Th2 cytokines, such as IL-13 or IL-4. However, mice overexpressing Smad2 in the airway epithelium showed significantly enhanced levels of IL-25 and activin A after HDM exposure. Blocking activin A with a neutralizing antibody prevented the increase in lung IL-25 and inhibited subsequent collagen deposition and also the enhanced airway hyperreactivity observed in the Smad2 overexpressing HDM-exposed mice. Conclusions: Epithelial overexpression of Smad2 can specifically alter airway hyperreactivity and remodeling in response to an aeroallergen. Moreover, we have identified novel roles for IL-25 and activin A in driving airway hyperreactivity and remodeling. PMID:20339149

  1. Electrolyte transport properties in distal small airways from cystic fibrosis pigs with implications for host defense.

    PubMed

    Li, Xiaopeng; 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; Meyerholz, David K; Stoltz, David A; Zabner, Joseph

    2016-04-01

    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

  2. Differential effects of cyclic and constant stress on ATP release and mucociliary transport by human airway epithelia.

    PubMed

    Button, Brian; Picher, Maryse; Boucher, Richard C

    2007-04-15

    In the lungs, the first line of defence against bacterial infection is the thin layer of airway surface liquid (ASL) lining the airway surface. The superficial airway epithelium exhibits complex regulatory pathways that blend ion transport to adjust ASL volume to maintain proper mucociliary clearance (MCC). We hypothesized that stresses generated by airflow and transmural pressures during breathing govern ASL volume by regulating the rate of epithelial ATP release. Luminal ATP, via interactions with apical membrane P2-purinoceptors, regulates the balance of active ion secretion versus absorption to maintain ASL volume at optimal levels for MCC. In this study we tested the hypothesis that cyclic compressive stress (CCS), mimicking normal tidal breathing, regulates ASL volume in airway epithelia. Polarized tracheobronchial epithelial cultures from normal and cystic fibrosis (CF) subjects responded to a range of CCS by increasing the rate of ATP release. In normal airway epithelia, the CCS-induced increase in ASL ATP concentration was sufficient to induce purinoceptor-mediated increases in ASL height and MCC, via inhibition of epithelial Na(+)-channel-mediated Na(+) absorption and stimulation of Cl(-) secretion through CFTR and the Ca(2+)-activated chloride channels. In contrast, static, non-oscillatory stress did not stimulate ATP release, ion transport or MCC, emphasizing the importance of rhythmic mechanical stress for airway defence. In CF airway cultures, which exhibit basal ASL depletion, CCS was partially effective, producing less ASL volume secretion than in normal cultures, but a level sufficient to restore MCC. The present data suggest that CCS may (1) regulate ASL volume in the normal lung and (2) improve clearance in the lungs of CF patients, potentially explaining the beneficial role of exercise in lung defence. PMID:17317749

  3. An Experimental Study of the Statistical Scaling of Turbulent Surface Pressure in the Atmospheric Boundary Layer

    NASA Astrophysics Data System (ADS)

    Lyons, G. W.; Murray, N. E.

    2015-12-01

    Turbulence in the atmospheric boundary layer (ABL) produces fluctuations in the static pressure. The instantaneous pressure at a point depends on an integral over the entire flow; therefore, the effects from turbulence far aloft may be felt at the earth's surface. The statistics of fluctuating pressure at the surface have been studied extensively in the context of wall-bounded engineering-type flows. At best, these neutral flows are a special case of the thermally-stratified ABL, but relatively few experimental studies have considered pressure at the ground under various stability conditions. Here the scaling of pressure statistics at the surface, particularly the spectral density, is reported over a range of convective and stable conditions for both inner and outer turbulence parameters. Measurements of turbulent surface pressure were made using low-frequency microphones buried flush to the ground in a field near Laramie, Wyoming. Simultaneous measurements from three near-surface sonic anemometers and a 50-meter wind tower give estimates of the mean surface-layer parameters. The normalization of the pressure spectrum with the inner scales collapses the spectra along the high-frequency viscous power-law band. The wall shear stress, Obukhov length, L, and horizontal integral scale, λ, are identified as outer scaling parameters for the surface pressure spectrum from an integral solution employing a Monin-Obukhov-similar profile and a simple model of inhomogeneous surface-layer turbulence. Normalization with the outer scales collapses the spectra at low frequencies. Spectral scaling also reveals trends with λ/L in the low-frequency region for both convective and stable boundary layers.

  4. Production and cell surface display of recombinant anthrax protective antigen on the surface layer of attenuated Bacillus anthracis.

    PubMed

    Wang, Yan-chun; Yuan, Sheng-ling; Tao, Hao-xia; Wang, Ling-chun; Zhang, Zhao-shan; Liu, Chun-jie

    2015-02-01

    To investigate the surface display of the anthrax protective antigen (PA) on attenuated Bacillus anthracis, a recombinant B. anthracis strain, named AP429 was constructed by integrating into the chromosome a translational fusion harboring the DNA fragments encoding the cell wall-targeting domain of the S-layer protein EA1 and the anthrax PA. Crerecombinase action at the loxP sites excised the antibiotic marker. Western blot analysis, fluorescence-activated cell sorting and immunofluorescence analysis confirmed that PA was successfully expressed on the S-layer of the recombinant antibiotic marker-free strain. Notwithstanding extensive proteolytic degradation of the hybrid protein SLHs-PA, quantitative ELISA revealed that approximately 8.1 × 10(6) molecules of SLHs-PA were gained from each Bacillus cell. Moreover, electron microscopy assay indicated that the typical S-layer structures could be clearly observed from the recombinant strain micrographs. PMID:25504373

  5. Magnetic properties and surface morphology of layered In2Se3 crystals intercalated with cobalt

    NASA Astrophysics Data System (ADS)

    Bakhtinov, A. P.; Boledzyuk, V. B.; Kovalyuk, Z. D.; Kudrynskyi, Z. R.; Lytvyn, O. S.; Shevchenko, A. D.

    2013-06-01

    The magnetic properties of layered Co x In2Se3 crystals electrochemically intercalated with cobalt in an external magnetic field and without a magnetic field and the morphology of the van der Waals surfaces of layers of these crystals have been investigated. It has been found that the ferromagnetic ordering at room temperature is observed only for Co x In2Se3 crystals intercalated in an external magnetic field. These crystals are nanocomposite materials that consist of a layered matrix and arrays of nanorings and nanowires formed from Co nanocrystals on the van der Waals surfaces of the In2Se3 layers. Cobalt nanocrystals in Co x In2Se3 crystals have a pyramidal equilibrium shape, which is characteristic of the face-centered cubic crystal structure, and their geometrical sizes are of the order of a few nanometers. The specific features of self-organization of cobalt magnetic nanostructures on the van der Waals surfaces of layered semiconductor crystals during their electrolytic intercalation in a magnetic field and the magnetic properties of these structures have been considered.

  6. A Simple Method to Assess Surface Roughness by Photothermal Investigation (PTR) Using an Effective Semitransparent Layer

    NASA Astrophysics Data System (ADS)

    Antoniow, J. S.; Chirtoc, M.; Drevet, R.; Jensen, C.; Benhayoune, H.

    2012-11-01

    Samples of a titanium-aluminum-vanadium alloy (Ti6Al4V) having different values of roughness are studied by photothermal radiometry. Among the numerous studies carried out on the influence of surface roughness on the photothermal signal, those that relate the air/substrate interfacial volume to an apparent homogeneous layer with effective thermal properties are considered. For such a system, a one-dimensional heat transfer model can successfully be used to describe the response to harmonic excitation up to high frequencies where the thermal diffusion length is of the order of magnitude as the roughness. The breakdown of the effective layer model at high frequencies has prompted some authors to develop more sophisticated methods to describe the complex phenomena encountered. In this study, it is proposed to keep the simple, effective layer model, but also to modify it by including an effective optical absorption coefficient and a reflection coefficient closely related to the surface characteristics. The effective layer becomes semitransparent to the excitation as it turns thermally thick (thickness/thermal diffusion length >1). The apparent thickness of the layer is shown to be directly related to the average difference between the maximum peak and the minimum trough of the surface profile and linearly correlated with the average roughness. This model can be used over a wide range of roughnesses.

  7. Substrate surface treatment and YSZ buffer layers by IBAD method for coated conductors

    NASA Astrophysics Data System (ADS)

    Feng, F.; Liu, R.; Chen, H.; Shi, K.; Wang, Z.; Wu, W.; Han, Z.

    2009-10-01

    In this work, an Ion Beam Assisted Deposition (IBAD) system was utilized to fabricate Yttria-Stabilized Zirconia (YSZ) template films for coated conductors. The surface of the Hastelloy C276 substrate was modified by rolling and electropolishing. The effect of the electropolishing parameters of the substrate on the texture of the YSZ buffer layers was studied. The electropolishing current and time were optimized for short samples of 1 cm×1 cm square shape as 1 A and 60 s, respectively. And the relationship between the roughness of the substrate surface and the texture of the YSZ layer is discussed. Reel-to-reel metal tape moving apparatus was installed and used to produce meter-long buffer layer for coated conductors. The YSZ template film was deposited by IBAD method on meter-long Hastelloy tape with tape shifting speed of 15-20 m/h, and the thickness of the buffer layer was up to about 1.7 μm. The Hastelloy substrate surface was measured by Atomic Force Microscope. The thickness of the YSZ films over length was measured by Thermal Field Emission Scan Electronic Microscopy. X Ray Diffraction Ω-scan and ϕ-scan measurements were performed in order to examine the out-of-plane and in-plane texture of the YSZ buffer layers, respectively.

  8. Enhanced surface plasmon resonance on a smooth silver film with a seed growth layer.

    PubMed

    Liu, Hong; Wang, Bing; Leong, Eunice S P; Yang, Ping; Zong, Yun; Si, Guangyuan; Teng, Jinghua; Maier, Stefan A

    2010-06-22

    This paper reports an effective method to enhance the surface plasmon resonance (SPR) on Ag films by using a thin Ni seed layer assisted deposition. Ag films with a thickness of about 50 nm were deposited by electron beam evaporation above an ultrathin Ni seed layer of approximately 2 nm on both silicon and quartz substrates. The root-mean-square (rms) surface roughness and the correlation length have been reduced from >4 nm and 28 nm for a pure Ag film to approximately 1.3 and 19 nm for Ag/Ni films, respectively. Both experimental and simulation results show that the Ag/Ni films exhibit an enhanced SPR over the pure Ag film with a narrower full width at half-maximum. Ag films with a Ge seed layer have also been prepared under the same conditions. The surface roughness can be reduced to less than 0.7 nm, but narrowing of the SPR curve is not observed due to increased absorptive damping in the Ge seed layer. Our results show that Ni acts as a roughness-diminishing growth layer for the Ag film while at the same time maintaining and enhancing the plasmonic properties of the combined structures. This points toward its use for low-loss plasmonic devices and optical metamaterials applications. PMID:20515054

  9. Quantitative study for surface properties of AlGaN epi-layers by ARXPS

    NASA Astrophysics Data System (ADS)

    Yang, Hongquan; Zhang, Xiong; Wang, Shuchang; Zhu, Min; Cui, Yiping

    2015-11-01

    The surface chemical properties of AlxGa1-xN (x=0.35, 0.47, 0.60) epi-layers grown on c-plane sapphire substrates by metal-organic chemical vapor deposition (MOCVD) were quantitatively characterized by angle-resolved X-ray photoelectron spectroscopy (ARXPS). The results suggested that the Ga Auger peak for the AlxGa1-xN epi-layers was greatly suppressed with increasing Al composition since the amount of N-Ga bonds were dramatically decreased. Moreover, more Al-O bonds were found near the surfaces of the AlxGa1-xN epi-layers with relatively high Al composition due to the large chemical affinity of aluminum to oxygen. In addition, the Al composition in the AlxGa1-xN epi-layers was showed to be non-uniform because Al atom has higher oxidizability and lower mobility than Ga atom, especially for the AlxGa1-xN epi-layers with relatively high Al composition. Our work should be very helpful to further investigation of the surface properties for making Al-containing III-nitrides optoelectronic devices.

  10. Effects of surface source/sink distributions on the flux-gradient similarity in the unstable surface layer

    NASA Astrophysics Data System (ADS)

    Huo, Qing; Cai, Xuhui; Kang, Ling; Zhang, Hongsheng; Song, Yu

    2015-01-01

    Based on the micrometeorological measurements at a heterogeneous farmland in the North China Plain, this study focused on the effects of surface source/sink distributions on the flux-gradient similarity theory in the unstable surface layer. Firstly, the quality of the micrometeorological measurements was evaluated by the analysis of the surface energy balance closure and the integral turbulence characteristics. In general, a 22 % deficit of energy balance was found at this site, with the sum of sensible and latent heat being smaller than the available energy. The normalized standard deviations of turbulent quantities behaved in accordance with Monin-Obukhov similarity theory. However, slight departures from the classical formulations might be caused by the surface heterogeneity. Then, the applicability of flux-gradient similarity over the heterogeneous surface was examined. The observed normalized wind gradients agreed with the classical universal function established over homogeneous surface. However, due to the effects of surface source/sink distributions, the observed normalized humidity and temperature gradients deviated from the classical universal functions. Our study shows that the classical universal functions, when adjusted by a coefficient considering the effects of surface heterogeneity, can be utilized to estimate fluxes via gradient method even though over the heterogeneous surface. This adjustment coefficient was found to decrease linearly from unity with the increase of the absolute value of the vertical flux divergence.

  11. Using of standard marine radar for determination of a water surface and an atmosphere near-surface layer parameters

    NASA Astrophysics Data System (ADS)

    Bogatov, Nikolay A.; Bakhanov, Victor V.; Ermoshkin, Aleksei V.; Kazakov, Vasily I.; Kemarskaya, Olga N.; Titov, Victor I.; Troitskaya, Yulia I.

    2014-10-01

    At present time radar methods of the seas and oceans diagnostics are actively developing. Using of the radar stations based on satellites and planes allows to receive information on a sea surface and a atmosphere near-surface layer with coverage of big water surface areas independently of day time. The developed methods of satellite radio images processing can be applied to marine radar stations. In Institute of Applied Physics RAS works on sea surface diagnostics systems development on the basis of standard marine radar are actively conducted. Despite smaller coverage of the territory in comparison with satellite data, marine radar have possibility to record spatially temporary radar images and to receive information on a surrounding situation quickly. This work deals with results of the researches which were conducted within the international expedition in the Atlantic Ocean in the autumn of 2012 on a route Rotterdam (Netherlands) - Ushuaya (Argentina) - Antarctica — Ushuaya. During this expedition a complex measurements of a sea surface, a atmosphere near-surface layer parameters and subsurface currents in the wide range of hydroweather conditions, including the storm were carried out. The system developed in IAP RAS on the basis of a marine radar ICOM MR-1200RII and the ADC (Analog Digital Converter) block for data recording on the personal computer was used. Display of a non-uniform near-surface current on sea surface radar images in storm conditions is shown. By means of the high-speed anemometer and meteorological station the measurements of the atmosphere parameters were carried out. Comparison of the anemometer data with calculated from radar images is carried out. Dependence of radar cross section from wind speed in the wide range of wind speeds, including storm conditions is investigated. Possibility of marine radar using for surface waves intensity and ice situation estimates also as icebergs detection is shown.

  12. Non-linear boundary-layer receptivity due to distributed surface roughness

    NASA Technical Reports Server (NTRS)

    Amer, Tahani Reffet; Selby, Gregory V.

    1995-01-01

    The process by which a laminar boundary layer internalizes the external disturbances in the form of instability waves is known as boundary-layer receptivity. The objective of the present research was to determine the effect of acoustic excitation on boundary-layer receptivity for a flat plate with distributed variable-amplitude surface roughness through measurements with a hot-wire probe. Tollmien-Schlichting (T-S) mode shapes due to surface-roughness receptivity have also been determined, analyzed, and shown to be in agreement with theory and other experimental work. It has been shown that there is a linear relationship between the surface roughness and receptivity for certain roughness configurations with constant roughness wavelength. In addition, strong nonlinear receptivity effects exist for certain surface roughness configurations over a band where the surface roughness and T-S wavelength are matched. The results from the present experiment follow the trends predicted by theory and other experimental work for linear receptivity. In addition, the results show the existence of nonlinear receptivity effects for certain combinations of surface roughness elements.

  13. A unified account of perceptual layering and surface appearance in terms of gamut relativity.

    PubMed

    Vladusich, Tony; McDonnell, Mark D

    2014-01-01

    When we look at the world--or a graphical depiction of the world--we perceive surface materials (e.g. a ceramic black and white checkerboard) independently of variations in illumination (e.g. shading or shadow) and atmospheric media (e.g. clouds or smoke). Such percepts are partly based on the way physical surfaces and media reflect and transmit light and partly on the way the human visual system processes the complex patterns of light reaching the eye. One way to understand how these percepts arise is to assume that the visual system parses patterns of light into layered perceptual representations of surfaces, illumination and atmospheric media, one seen through another. Despite a great deal of previous experimental and modelling work on layered representation, however, a unified computational model of key perceptual demonstrations is still lacking. Here we present the first general computational model of perceptual layering and surface appearance--based on a boarder theoretical framework called gamut relativity--that is consistent with these demonstrations. The model (a) qualitatively explains striking effects of perceptual transparency, figure-ground separation and lightness, (b) quantitatively accounts for the role of stimulus- and task-driven constraints on perceptual matching performance, and (c) unifies two prominent theoretical frameworks for understanding surface appearance. The model thereby provides novel insights into the remarkable capacity of the human visual system to represent and identify surface materials, illumination and atmospheric media, which can be exploited in computer graphics applications. PMID:25402466

  14. Surface reconstruction and chemical evolution of stoichiometric layered cathode materials for lithium-ion batteries.

    PubMed

    Lin, Feng; Markus, Isaac M; Nordlund, Dennis; Weng, Tsu-Chien; Asta, Mark D; Xin, Huolin L; Doeff, Marca M

    2014-01-01

    The present study sheds light on the long-standing challenges associated with high-voltage operation of LiNi(x)Mn(x)Co(1-2x)O2 cathode materials for lithium-ion batteries. Using correlated ensemble-averaged high-throughput X-ray absorption spectroscopy and spatially resolved electron microscopy and spectroscopy, here we report structural reconstruction (formation of a surface reduced layer, to transition) and chemical evolution (formation of a surface reaction layer) at the surface of LiNi(x)Mn(x)Co(1-2x)O2 particles. These are primarily responsible for the prevailing capacity fading and impedance buildup under high-voltage cycling conditions, as well as the first-cycle coulombic inefficiency. It was found that the surface reconstruction exhibits a strong anisotropic characteristic, which predominantly occurs along lithium diffusion channels. Furthermore, the surface reaction layer is composed of lithium fluoride embedded in a complex organic matrix. This work sets a refined example for the study of surface reconstruction and chemical evolution in battery materials using combined diagnostic tools at complementary length scales. PMID:24670975

  15. The dynamic deformation of a layered viscoelastic medium under surface excitation.

    PubMed

    Aglyamov, Salavat R; Wang, Shang; Karpiouk, Andrei B; Li, Jiasong; Twa, Michael; Emelianov, Stanislav Y; Larin, Kirill V

    2015-06-01

    In this study the dynamic behavior of a layered viscoelastic medium in response to the harmonic and impulsive acoustic radiation force applied to its surface was investigated both theoretically and experimentally. An analytical solution for a layered viscoelastic compressible medium in frequency and time domains was obtained using the Hankel transform. A special incompressible case was considered to model soft biological tissues. To verify our theoretical model, experiments were performed using tissue-like gel-based phantoms with varying mechanical properties. A 3.5 MHz single-element focused ultrasound transducer was used to apply the radiation force at the surface of the phantoms. A phase-sensitive optical coherence tomography system was used to track the displacements of the phantom surface. Theoretically predicted displacements were compared with experimental measurements. The role of the depth dependence of the elastic properties of a medium in its response to an acoustic pulse at the surface was studied. It was shown that the low-frequency vibrations at the surface are more sensitive to the deep layers than high-frequency ones. Therefore, the proposed model in combination with spectral analysis can be used to evaluate depth-dependent distribution of the mechanical properties based on the measurements of the surface deformation. PMID:25974168

  16. Non-linear boundary-layer receptivity due to distributed surface roughness

    NASA Technical Reports Server (NTRS)

    Amer, Tahani Reffet

    1995-01-01

    The process by which a laminar boundary layer internalizes the external disturbances in the form of instability waves is known as boundary-layer receptivity. The objective of the present research was to determine the effect of acoustic excitation on boundary-layer receptivity for a flat plate with distributed variable-amplitude surface roughness through measurements with a hot-wire probe. Tollmien-Schlichting mode shapes due to surface roughness receptivity have also been determined, analyzed, and shown to be in agreement with theory and other experimental work. It has been shown that there is a linear relationship between the surface roughness and receptivity for certain roughness configurations with constant roughness wavelength. In addition, strong non-linear receptivity effects exist for certain surface roughness configurations over a band where the surface roughness and T-S wavelength are matched. The results from the present experiment follow the trends predicted by theory and other experimental work for linear receptivity. In addition, the results show the existence of non-linear receptivity effects for certain combinations of surface roughness elements.

  17. A Unified Account of Perceptual Layering and Surface Appearance in Terms of Gamut Relativity

    PubMed Central

    Vladusich, Tony; McDonnell, Mark D.

    2014-01-01

    When we look at the world—or a graphical depiction of the world—we perceive surface materials (e.g. a ceramic black and white checkerboard) independently of variations in illumination (e.g. shading or shadow) and atmospheric media (e.g. clouds or smoke). Such percepts are partly based on the way physical surfaces and media reflect and transmit light and partly on the way the human visual system processes the complex patterns of light reaching the eye. One way to understand how these percepts arise is to assume that the visual system parses patterns of light into layered perceptual representations of surfaces, illumination and atmospheric media, one seen through another. Despite a great deal of previous experimental and modelling work on layered representation, however, a unified computational model of key perceptual demonstrations is still lacking. Here we present the first general computational model of perceptual layering and surface appearance—based on a boarder theoretical framework called gamut relativity—that is consistent with these demonstrations. The model (a) qualitatively explains striking effects of perceptual transparency, figure-ground separation and lightness, (b) quantitatively accounts for the role of stimulus- and task-driven constraints on perceptual matching performance, and (c) unifies two prominent theoretical frameworks for understanding surface appearance. The model thereby provides novel insights into the remarkable capacity of the human visual system to represent and identify surface materials, illumination and atmospheric media, which can be exploited in computer graphics applications. PMID:25402466

  18. On the development of boundary layer secondary circulations resulting from horizontally varying surface heat flux

    SciTech Connect

    Shaw, W.J.; Doran, J.C.

    1994-03-01

    During the last decade there has been a surge in efforts to understand the processes at work in the inhomogeneous atmospheric boundary layer. Much of the interest in the problem has been driven by increasingly urgent needs to develop accurate assessments of man`s Contribution to climate change. It has been argued that subgrid-scale secondary circulations in the boundary layer can cause significant errors in parameterized turbulent surface fluxes. Such circulations -- variously termed ``inland breezes``, ``lake breezes``, ``snow breezes``, or ``nonclassical mesoscale circulations`` are becoming widely discussed and modeled. Because surface fluxes are part of the lower boundary condition for global climate models, it is important to understand when these circulations occur and what their effects are on overall turbulent transfer. What are not yet clear are the combinations of the ambient wind and the horizontal scale and intensity of surface flux variability under which we may expect boundary layer secondary circulations to occur. Several authors have modeled the development of these circulations for ad hoc situations of alternating surface characteristics, and SA have developed one parameterization relating the scale of surface heat flux variability and the ambient wind to the evolution of NCMCs. In this paper we present observations, collected in a region of inhomogeneous surface fluxes, that suggest the development of a ``farm breeze``, and we develop an alternative scaling argument to that of SA that better represents our measurement conditions.

  19. Role of uppermost superficial surface layer of articular cartilage in the lubrication mechanism of joints

    PubMed Central

    KUMAR, P.; OKA, M.; TOGUCHIDA, J.; KOBAYASHI, M.; UCHIDA, E.; NAKAMURA, T.; TANAKA, K.

    2001-01-01

    The uppermost superficial surface layer of articular cartilage, the ‘lamina splendens’ which provides a very low friction lubrication surface in articular joints, was investigated using atomic force microscopy (AFM). Complementary specimens were also observed under SEM at −10 °C without dehydration or sputter ion coating. Fresh adult pig osteochondral specimens were prepared from the patellas of pig knee joints and digested with the enzymes, hyaluronidase, chondroitinase ABC and alkaline protease. Friction coefficients between a pyrex glass plate and the osteochondral specimens digested by enzymes as well as natural (undigested) specimens were measured, using a thrust collar apparatus. Normal saline, hyaluronic acid (HA) and a mixture of albumin, globulin, HA (AGH) were used as lubrication media. The surface irregularities usually observed in SEM studies were not apparent under AFM. The articular cartilage surface was resistant to hyaluronidase and also to chondroitinase ABC, but a fibrous structure was exhibited in alkaline protease enzymes-digested specimens. AFM analysis revealed that the thickness of the uppermost superficial surface layer of articular cartilage was between 800 nm and 2 μm in adult pig articular cartilage. The coefficient of friction (c.f.) was significantly higher in chondroitinase ABC and alkaline protease enzymes digested specimens. Generally, in normal saline lubrication medium, c.f. was higher in comparison to HA and AGH lubrication media. The role of the uppermost, superficial surface layer of articular cartilage in the lubrication mechanism of joints is discussed. PMID:11554503

  20. Role of uppermost superficial surface layer of articular cartilage in the lubrication mechanism of joints.

    PubMed

    Kumar, P; Oka, M; Toguchida, J; Kobayashi, M; Uchida, E; Nakamura, T; Tanaka, K

    2001-09-01

    The uppermost superficial surface layer of articular cartilage, the 'lamina splendens' which provides a very low friction lubrication surface in articular joints, was investigated using atomic force microscopy (AFM). Complementary specimens were also observed under SEM at -10 degrees C without dehydration or sputter ion coating. Fresh adult pig osteochondral specimens were prepared from the patellas of pig knee joints and digested with the enzymes, hyaluronidase, chondroitinase ABC and alkaline protease. Friction coefficients between a pyrex glass plate and the osteochondral specimens digested by enzymes as well as natural (undigested) specimens were measured, using a thrust collar apparatus. Normal saline, hyaluronic acid (HA) and a mixture of albumin, globulin, HA (AGH) were used as lubrication media. The surface irregularities usually observed in SEM studies were not apparent under AFM. The articular cartilage surface was resistant to hyaluronidase and also to chondroitinase ABC, but a fibrous structure was exhibited in alkaline protease enzymes-digested specimens. AFM analysis revealed that the thickness of the uppermost superficial surface layer of articular cartilage was between 800 nm and 2 microm in adult pig articular cartilage. The coefficient of friction (c.f.) was significantly higher in chondroitinase ABC and alkaline protease enzymes digested specimens. Generally, in normal saline lubrication medium, c.f. was higher in comparison to HA and AGH lubrication media. The role of the uppermost, superficial surface layer of articular cartilage in the lubrication mechanism of joints is discussed. PMID:11554503

  1. Optical luminescence studies of the ethyl xanthate adsorption layer on the surface of sphalerite minerals

    NASA Astrophysics Data System (ADS)

    Todoran, R.; Todoran, D.; Szakács, Zs.

    2016-01-01

    In this work we propose optical luminescence measurements as a method to evaluate the kinetics of adsorption processes. Measurement of the intensity of the integral optical radiation obtained from the mineral-xanthate interface layer, stimulated with a monochromatic pulsating optical signal, as a function of time were made. The luminescence radiation was obtained from the thin interface layer formed at the separation surface between the sphalerite natural mineral and potassium ethyl xanthate solution, for different solution concentrations and pH-es at the constant industry standard temperature. This method enabled us to determine the time to achieve dynamic equilibrium in the formation of the interface layer of approximately 20 min, gaining information on the adsorption kinetics in the case of xanthate on mineral surface and leading to the optimization of the industrial froth flotation process.

  2. MHD-instability of the equilibrium state of the surface of a conductive liquid thin layer.

    NASA Astrophysics Data System (ADS)

    Kolesnichenko, I.; Khripchenko, S.

    2001-12-01

    In this paper, the phenomenon of MHD-instability of the surface equilibrium of a conductive liquid thin layer under small long-wave disturbances is investigated. The layer is under the action of electric and magnetic fields. The equations of motion and oscillation of the layer surface about the equilibrium state are presented. The equation of oscillation is investigated by the methods of the linear stability theory. A numerical analysis of the equations of motion allows to obtain some neutral curves for different values of the magnetic fields. These curves divide the region of process parameters into two domains of stability and instability for small long-wave disturbances. Figs 2, Refs 5.

  3. Modeling of transition and surface roughness effects in boundary-layer flows

    NASA Technical Reports Server (NTRS)

    Feiereisen, W. J.; Acharya, M.

    1986-01-01

    Experiments were carried out to examine the influence of three-dimensional, stochastic roughness on the growth of incompressible turbulent boundary layers, as well as the effect of streamwise pressure gradients and freestream turbulence intensity on smooth-wall boundary-layer transition. The modeling of these effects in a two-dimensional boundary-layer computation program was examined with the help of the experiments. A model for surface roughness was developed that relates directly measurable statistical parameters quantifying the roughness geometry to the aerodynamic effects. This model should be valid for a limited class of surfaces found on turbomachinery blading and in other engineering applications. Commonly used criteria for the transition onset performed poorly and presumably need to be modified to account for other factors influencing the process.

  4. Electron microscopy of an aluminum layer grown on the vicinal surface of a gallium arsenide substrate

    SciTech Connect

    Lovygin, M. V. Borgardt, N. I.; Kazakov, I. P.; Seibt, M.

    2015-03-15

    A thin Al layer grown by molecular-beam epitaxy on a misoriented GaAs (100) substrate is studied by transmission electron microscopy. Electron diffraction data and bright-field, dark-field, and high-resolution images show that, in the layer, there are Al grains of three types of crystallographic orientation: Al (100), Al (110), and Al (110)R. The specific structural features of the interfaces between the differently oriented grains and substrate are studied by digital processing of the high-resolution images. From quantitative analysis of the dark-field images, the relative content and sizes of the differently oriented grains are determined. It is found that atomic steps at the substrate surface cause an increase in the fraction and sizes of Al (110)R grains and a decrease in the fraction of Al (100) grains, compared to the corresponding fractions and sizes in the layer grown on a singular substrate surface.

  5. Fabrication of nanocrystalline surface composite layer on Cu plate under ball collisions.

    PubMed

    Romankov, S; Park, Y C; Yoon, J M

    2014-10-01

    It was demonstrated that the severe plastic deformation of a surface induced by repeated ball collisions can be effectively used for fabrication of the nanocrystalline surface composite layers. The Cu disk was fixed at the top of a vibration chamber and ball treated. Al, Zr, Ni, Co and Fe were introduced into a Cu plate as contaminants from the grinding media one after the other by 15-min ball treatment. The composite structure was formed as a result of mechanical intermixing of the components. The particle size in as-fabricated layer ranged from 2 nm to 20 nm, with average values of about 7 nm. As-fabricated layer contained non-equilibrium multicomponent solid solution based on FCC Cu crystal structure, Zr-based phase, nanosized steel debris and amorphous phase. The hardness of the as-fabricated composite was almost ten times that of the initial Cu plate. PMID:25942932

  6. Optical luminescence studies of the ethyl xanthate adsorption layer on the surface of sphalerite minerals.

    PubMed

    Todoran, R; Todoran, D; Szakács, Zs

    2016-01-01

    In this work we propose optical luminescence measurements as a method to evaluate the kinetics of adsorption processes. Measurement of the intensity of the integral optical radiation obtained from the mineral-xanthate interface layer, stimulated with a monochromatic pulsating optical signal, as a function of time were made. The luminescence radiation was obtained from the thin interface layer formed at the separation surface between the sphalerite natural mineral and potassium ethyl xanthate solution, for different solution concentrations and pH-es at the constant industry standard temperature. This method enabled us to determine the time to achieve dynamic equilibrium in the formation of the interface layer of approximately 20min, gaining information on the adsorption kinetics in the case of xanthate on mineral surface and leading to the optimization of the industrial froth flotation process. PMID:25619858

  7. Brachycephalic airway syndrome: management.

    PubMed

    Lodato, Dena L; Hedlund, Cheryl S

    2012-08-01

    Brachycephalic airway syndrome (BAS) is a group of primary and secondary abnormalities that result in upper airway obstruction. Several of these abnormalities can be addressed medically and/or surgically to improve quality of life. This article reviews potential complications, anesthetic considerations, recovery strategies, and outcomes associated with medical and surgical management of BAS. PMID:22935992

  8. Simvastatin Inhibits Airway Hyperreactivity

    PubMed Central

    Zeki, Amir A.; Franzi, Lisa; Last, Jerold; Kenyon, Nicholas J.

    2009-01-01

    Rationale: Statin use has been linked to improved lung health in asthma and chronic obstructive pulmonary disease. We hypothesize that statins inhibit allergic airway inflammation and reduce airway hyperreactivity via a mevalonate-dependent mechanism. Objectives: To determine whether simvastatin attenuates airway inflammation and improves lung physiology by mevalonate pathway inhibition. Methods: BALB/c mice were sensitized to ovalbumin over 4 weeks and exposed to 1% ovalbumin aerosol over 2 weeks. Simvastatin (40 mg/kg) or simvastatin plus mevalonate (20 mg/kg) was injected intraperitoneally before each ovalbumin exposure. Measurements and Main Results: Simvastatin reduced total lung lavage leukocytes, eosinophils, and macrophages (P < 0.05) in the ovalbumin-exposed mice. Cotreatment with mevalonate, in addition to simvastatin, reversed the antiinflammatory effects seen with simvastatin alone (P < 0.05). Lung lavage IL-4, IL-13, and tumor necrosis factor-α levels were all reduced by treatment with simvastatin (P < 0.05). Simvastatin treatment before methacholine bronchial challenge increased lung compliance and reduced airway hyperreactivity (P = 0.0001). Conclusions: Simvastatin attenuates allergic airway inflammation, inhibits key helper T cell type 1 and 2 chemokines, and improves lung physiology in a mouse model of asthma. The mevalonate pathway appears to modulate allergic airway inflammation, while the beneficial effects of simvastatin on lung compliance and airway hyperreactivity may be independent of the mevalonate pathway. Simvastatin and similar agents that modulate the mevalonate pathway may prove to be treatments for inflammatory airway diseases, such as asthma. PMID:19608720

  9. Corrosion product layers on magnesium alloys AZ31 and AZ61: Surface chemistry and protective ability

    NASA Astrophysics Data System (ADS)

    Feliu, S.; Llorente, I.

    2015-08-01

    This paper studies the chemical composition of the corrosion product layers formed on magnesium alloys AZ31 and AZ61 following immersion in 0.6 M NaCl, with a view to better understanding their protective action. Relative differences in the chemical nature of the layers were quantified by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDX) and low-angle X-ray diffraction (XRD). Corrosion behavior was investigated by Electrochemical Impedance Spectroscopy (EIS) and hydrogen evolution measurement. An inhibitive effect from the corrosion product layers was observed from EIS, principally in the case of AZ31, as confirmed by hydrogen evolution tests. A link was found between carbonate enrichment observed by XPS in the surface of the corrosion product layer, concomitant with the increase in the protective properties observed by EIS.

  10. Goertler instability in compressible boundary layers along curved surfaces with suction and cooling

    NASA Technical Reports Server (NTRS)

    El-Hady, N.; Verma, A. K.

    1982-01-01

    The Goertler instability of the laminar compressible boundary layer flows along concave surfaces is investigated. The linearized disturbance equations for the three-dimensional, counter-rotating streamwise vortices in two-dimensional boundary layers are presented in an orthogonal curvilinear coordinate. The basic approximation of the disturbance equations, that includes the effect of the growth of the boundary layer, is considered and solved numerically. The effect of compressibility on critical stability limits, growth rates, and amplitude ratios of the vortices is evaluated for a range of Mach numbers for 0 to 5. The effect of wall cooling and suction of the boundary layer on the development of Goertler vortices is investigated for different Mach numbers.

  11. Figure of merit enhancement of surface plasmon resonance sensors using absentee layer.

    PubMed

    Chen, Zhaoyang; Zhao, Xin; Lin, Chengyou; Chen, Shujing; Yin, Liang; Ding, Yingchun

    2016-09-01

    By adding an absentee layer on the top of the metallic layer, the figure of merit (FOM) of a surface plasmon resonance (SPR) sensor with Kretschmann configuration was enhanced, without changing the resonance angle and the reflectance at the resonance angle. Comparing with a traditional SPR sensor, the FOM of the SPR sensor with an absentee layer composed of either 1367 nm thick KCl or 235 nm thick Si3N4 can be improved by 5.53% or 11.41%, respectively. The enhancement of the FOM should be attributed to the faster decrease of the full width at half-maximum than the sensitivity after an absentee layer was applied in the SPR sensor. PMID:27607256

  12. Surface-Engineered Graphene Quantum Dots Incorporated into Polymer Layers for High Performance Organic Photovoltaics

    PubMed Central

    Kim, Jung Kyu; Kim, Sang Jin; Park, Myung Jin; Bae, Sukang; Cho, Sung-Pyo; Du, Qing Guo; Wang, Dong Hwan; Park, Jong Hyeok; Hong, Byung Hee

    2015-01-01

    Graphene quantum dots (GQDs), a newly emerging 0-dimensional graphene based material, have been widely exploited in optoelectronic devices due to their tunable optical and electronic properties depending on their functional groups. Moreover, the dispersibility of GQDs in common solvents depending on hydrophobicity or hydrophilicity can be controlled by chemical functionalization, which is particularly important for homogeneous incorporation into various polymer layers. Here we report that a surface-engineered GQD-incorporated polymer photovoltaic device shows enhanced power conversion efficiency (PCE), where the oxygen-related functionalization of GQDs enabled good dispersity in a PEDOT:PSS hole extraction layer, leading to significantly improved short circuit current density (Jsc) value. To maximize the PCE of the device, hydrophobic GQDs that are hydrothermally reduced (rGQD) were additionally incorporated in a bulk-heterojunction layer, which is found to promote a synergistic effect with the GQD-incorporated hole extraction layer. PMID:26392211

  13. Surface recombination velocity and diffusion length of minority carriers in heavily doped silicon layers

    NASA Technical Reports Server (NTRS)

    Gatos, H. C.; Watanabe, M.; Actor, G.

    1977-01-01

    Quantitative analysis of the electron beam-induced current and the dependence of the effective diffusion length of the minority carriers on the penetration depth of the electron beam were employed for the analysis of the carrier recombination characteristics in heavily doped silicon layers. The analysis is based on the concept of the effective excitation strength of the carriers which takes into consideration all possible recombination sources. Two dimensional mapping of the surface recombination velocity of P-diffused Si layers will be presented together with a three dimensional mapping of minority carrier lifetime in ion implanted Si. Layers heavily doped with As exhibit improved recombination characteristics as compared to those of the layers doped with P.

  14. Surface state and normal layer effects in high T{sub c} superconductors

    SciTech Connect

    Klemm, R.A.; Ledvij, M.; Liu, Samuel H.

    1996-01-01

    In addition to the conducting CuO{sub 2} (S) layers, most high-{Tc}, superconductors also contain other conducting (N) layers, which are only superconducting due to the proximity effect. The combination of S and N layers can give rise to complicated electronic densities of states, leading to quasilinear penetration depth and NMR relaxation rate behavior at low temperatures. Surface states can also complicate the analysis of tunneling and photoemission measurements. Moreover, geometrical considerations and inhomogeneously trapped flux are possible explanations of the paramagnetic Meissner effect and of corner and ring SQUID experiments. Hence, all of the above experiments could be consistent with isotropic s-wave superconductive within the S layers.

  15. Correction of localized shape errors on optical surfaces by altering the localized density of surface or near-surface layers

    DOEpatents

    Taylor, John S.; Folta, James A.; Montcalm, Claude

    2005-01-18

    Figure errors are corrected on optical or other precision surfaces by changing the local density of material in a zone at or near the surface. Optical surface height is correlated with the localized density of the material within the same region. A change in the height of the optical surface can then be caused by a change in the localized density of the material at or near the surface.

  16. Influence of substrate preparation on the shaping of the topography of the surface of nanoceramic oxide layers

    NASA Astrophysics Data System (ADS)

    Bara, Marek; Kubica, Marek

    2014-02-01

    The paper discusses the shaping mechanism and changes occurring in the structure and topography of the surface of nanoceramic oxide layers during their formation. The paper presents the influence of substrate preparation on the surface topography of oxide layers. The layers were produced via hard anodizing on the EN AW-5251 aluminum alloy. The layers obtained were subjected to microscope examinations, image and chemical composition analyses, and stereometric examinations. Heredity of substrate properties in the topography of the surface of nanoceramic oxide layers formed as a result of electrochemical oxidation has been shown.

  17. Microthermal measurements of the surface layer and its contribution to the seeing

    NASA Astrophysics Data System (ADS)

    Guerra, Juan Carlos; Gonzalez, Manuel

    2006-06-01

    In order to obtain more knowledge of the atmospheric surface layer, an internet based remote monitoring system has been developed. The surface layer turbulence degrades the images to a degree that will depend on the terrain, vegetation, structures and earth thermal effects on the local site. To find the contribution of these micro-thermal fluctuations introduced by the surface layer to the image degradation a series of fast response temperature sensor are placed at different heights and a front-end electronic system is used to control the sensors and manage the Ethernet communication to a remote PC. From the instantaneous temperature differences between the micro thermocouple systems we can derive the temperature structure function coefficient C t2 which is related to the refractive index structure function coefficient C n2. Data from the micro thermocouples must be read at fairly high frequency and recorded in a fashion which may be synchronised. The long term surface layer turbulence measurements are stored in a remote PC.

  18. Extending the Diffuse Layer Model of Surface Acidity Behavior: III. Estimating Bound Site Activity Coefficients

    EPA Science Inventory

    Although detailed thermodynamic analyses of the 2-pK diffuse layer surface complexation model generally specify bound site activity coefficients for the purpose of accounting for those non-ideal excess free energies contributing to bound site electrochemical potentials, in applic...

  19. A SIMPLE, EFFICIENT SOLUTION OF FLUX-PROFILE RELATIONSHIPS IN THE ATMOSPHERIC SURFACE LAYER

    EPA Science Inventory

    This note describes a simple scheme for analytical estimation of the surface layer similarity functions from state variables. What distinguishes this note from the many previous papers on this topic is that this method is specifically targeted for numerical models where simplici...

  20. Surface fluxes and convective boundary layer instability in summer over harvested wheat fields in Oklahoma

    NASA Astrophysics Data System (ADS)

    Li, W.; Barros, A. P.

    2008-05-01

    Vertical profiles of wind, pressure, air temperature and humidity up to 500 m obtained from measurements by a tethersonde system were used in combination with upper level temperature and humidity soundings from Rapid Update Cycle (RUC), to calculate Convective Available Potential Energy (CAPE) in an unstable boundary layer. The surface fluxes of sensible and latent heat were also calculated based on turbulent similarity theory for the atmospheric surface layer. The measurements were performed during the Cloud and Land Surface Interaction Campaign (CLASIC) June 2007 that includes pre-storm and post-storm conditions for a record monthly rainfall in excess of 300 mm at the site. The daytime trajectories of the surface layer in the Relative-Humidity and Bowen Ratio phase-space are consistent with the rainfall and aridity attractors in previous studies, with strong decrease in the post-storm periods. The decrease of Bowen ratio was the result of a strong decrease in the magnitude of sensible heat fluxes. The latent heat fluxes in the post-storm environment were not significantly different from the pre-storm environment, which is explained by a significant decrease in the net radiation. High soil moisture and increased moisture in boundary layer in the post-storm environment led to sustained low-level instability and daily evening showers. The diurnal cycle of potential temperature and specific humidity during the duration of the field campaign with an emphasis on conditions before and after one major rainy event are also discussed in this study.

  1. Structure fragmentation of a surface layer of commercial purity titanium during ultrasonic impact treatment

    NASA Astrophysics Data System (ADS)

    Kozelskaya, Anna; Panin, Alexey; Kazachenok, Marina; Hairullin, Rustam; Sinyakova, Elena; Pochivalov, Yurii; Perevalova, Olga

    2015-10-01

    The mechanisms of surface layer fragmentation of titanium specimens subjected to ultrasonic impact treatment is investigated by atomic force microscopy, transmission electron microscopy and electron backscatter diffraction. It is shown that the twin boundaries Σ7b and Σ11b are unable to be strong obstacles for propagation of dislocations and other twins.

  2. Structure fragmentation of a surface layer of commercial purity titanium during ultrasonic impact treatment

    SciTech Connect

    Kozelskaya, Anna Kazachenok, Marina Sinyakova, Elena Pochivalov, Yurii Perevalova, Olga; Panin, Alexey Hairullin, Rustam

    2015-10-27

    The mechanisms of surface layer fragmentation of titanium specimens subjected to ultrasonic impact treatment is investigated by atomic force microscopy, transmission electron microscopy and electron backscatter diffraction. It is shown that the twin boundaries Σ7b and Σ11b are unable to be strong obstacles for propagation of dislocations and other twins.

  3. Formation of tubes during self-assembly of bacterial surface layers.

    PubMed

    Bobeth, Manfred; Blecha, Andreas; Blüher, Anja; Mertig, Michael; Korkmaz, Nuriye; Ostermann, Kai; Rödel, Gerhard; Pompe, Wolfgang

    2011-12-20

    Based on experimental studies on tube formation during self-assembly of bacterial surface (S)-layers, a mechanistic model for describing the underlying basic mechanisms is proposed and the effect of process parameters on growth velocity and tube radius is investigated. The S-layer is modeled as a curved sheet with discrete binding sites for the association of monomers distributed along the S-layer edges. Reported changes of the tube radius owing to genetic protein modifications are explained within the framework of continuum mechanics. S-layer growth velocity and shape development are analyzed by Monte Carlo simulation in their dependence on the attachment and detachment frequencies of monomers at the S-layer. For curved S-layer patches, a criterion for the formation of S-layer tubes is derived. Accordingly, tubes can form only within a certain range of the initial monomer concentration. Furthermore, the effect of calcium ion concentration on tube formation is discussed, including recent experimental findings on the calcium effect. PMID:22029537

  4. Layers: A molecular surface peeling algorithm and its applications to analyze protein structures

    PubMed Central

    Karampudi, Naga Bhushana Rao; Bahadur, Ranjit Prasad

    2015-01-01

    We present an algorithm ‘Layers’ to peel the atoms of proteins as layers. Using Layers we show an efficient way to transform protein structures into 2D pattern, named residue transition pattern (RTP), which is independent of molecular orientations. RTP explains the folding patterns of proteins and hence identification of similarity between proteins is simple and reliable using RTP than with the standard sequence or structure based methods. Moreover, Layers generates a fine-tunable coarse model for the molecular surface by using non-random sampling. The coarse model can be used for shape comparison, protein recognition and ligand design. Additionally, Layers can be used to develop biased initial configuration of molecules for protein folding simulations. We have developed a random forest classifier to predict the RTP of a given polypeptide sequence. Layers is a standalone application; however, it can be merged with other applications to reduce the computational load when working with large datasets of protein structures. Layers is available freely at http://www.csb.iitkgp.ernet.in/applications/mol_layers/main. PMID:26553411

  5. Layers: A molecular surface peeling algorithm and its applications to analyze protein structures

    NASA Astrophysics Data System (ADS)

    Karampudi, Naga Bhushana Rao; Bahadur, Ranjit Prasad

    2015-11-01

    We present an algorithm ‘Layers’ to peel the atoms of proteins as layers. Using Layers we show an efficient way to transform protein structures into 2D pattern, named residue transition pattern (RTP), which is independent of molecular orientations. RTP explains the folding patterns of proteins and hence identification of similarity between proteins is simple and reliable using RTP than with the standard sequence or structure based methods. Moreover, Layers generates a fine-tunable coarse model for the molecular surface by using non-random sampling. The coarse model can be used for shape comparison, protein recognition and ligand design. Additionally, Layers can be used to develop biased initial configuration of molecules for protein folding simulations. We have developed a random forest classifier to predict the RTP of a given polypeptide sequence. Layers is a standalone application; however, it can be merged with other applications to reduce the computational load when working with large datasets of protein structures. Layers is available freely at http://www.csb.iitkgp.ernet.in/applications/mol_layers/main.

  6. Regulation of airway neurogenic inflammation by neutral endopeptidase.

    PubMed

    Di Maria, G U; Bellofiore, S; Geppetti, P

    1998-12-01

    Airway neurogenic inflammation is caused by tachykinins released from peripheral nerve endings of sensory neurons within the airways, and is characterized by plasma protein extravasation, airway smooth muscle contraction and increased secretion of mucus. Tachykinins are degraded and inactivated by neutral endopeptidase (NEP), a membrane-bound metallopeptidase, which is located mainly at the surface of airway epithelial cells, but is also present in airway smooth muscle cells, submucosal gland cells and fibroblasts. The key role of NEP in limiting and regulating the neurogenic inflammation provoked by different stimuli has been demonstrated in a large series of studies published in recent years. It has also been shown that a variety of factors, which are relevant for airway diseases, including viral infections, allergen exposure, inhalation of cigarette smoke and other respiratory irritants, is able to reduce NEP activity, thus enhancing the effects of tachykinins within the airways. On the basis of these observations, the reduction of neutral endopeptidase activity may be regarded as a factor that switches neurogenic airway responses from their physiological and protective functions to a detrimental role that increases and perpetuates airway inflammation. However, further studies are needed to assess the role of neutral endopeptidase down regulation in the pathogenesis of asthma and other inflammatory airway diseases. PMID:9877509

  7. 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.

  8. Combined effects of surface conditions, boundary layer dynamics and chemistry on diurnal SOA evolution

    NASA Astrophysics Data System (ADS)

    Janssen, R. H. H.; Vilà-Guerau de Arellano, J.; Ganzeveld, L. N.; Kabat, P.; Jimenez, J. L.; Farmer, D. K.; van Heerwaarden, C. C.; Mammarella, I.

    2012-08-01

    We study the combined effects of land surface conditions, atmospheric boundary layer dynamics and chemistry on the diurnal evolution of biogenic secondary organic aerosol in the atmospheric boundary layer, using a model that contains the essentials of all these components. First, we evaluate the model for a case study in Hyytiälä, Finland, and find that it is able to satisfactorily reproduce the observed dynamics and gas-phase chemistry. We show that the exchange of organic aerosol between the free troposphere and the boundary layer (entrainment) must be taken into account in order to explain the observed diurnal cycle in organic aerosol (OA) concentration. An examination of the budgets of organic aerosol and terpene concentrations show that the former is dominated by entrainment, while the latter is mainly driven by emission and chemical transformation. We systematically investigate the role of the land surface, which governs both the surface energy balance partitioning and terpene emissions, and the large-scale atmospheric process of vertical subsidence. Entrainment is especially important for the dilution of organic aerosol concentrations under conditions of dry soils and low terpene emissions. Subsidence suppresses boundary layer growth while enhancing entrainment. Therefore, it influences the relationship between organic aerosol and terpene concentrations. Our findings indicate that the diurnal evolution of secondary organic aerosols (SOA) in the boundary layer is the result of coupled effects of the l