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Sample records for brush border membrane

  1. Taurocholate transport by brush-border membrane vesicles from the developing rabbit ileum: Structure/function relationships

    International Nuclear Information System (INIS)

    Schwarz, S.M.; Watkins, J.B.; Ling, S.C.

    1990-01-01

    To examine the ontogenesis of bile acid transport in the rabbit ileum, brush-border membrane vesicles (12- to 20-fold purified) were prepared from 14- to 49-day-old animals. Taurocholate uptake was characterized by the emergence of secondary active, Na(+)-dependent transport at the start of weaning (21 days). Transient intravesicular accumulation (overshoot) of taurocholate occurred at 5-10 s of incubation, and the overshoot maximum increased significantly from 21 days (349.2 +/- 22.4 nmol/mg protein) to 35 days (569.0 +/- 84.3 nmol/mg protein; p less than 0.001), without further increase at maturity (49 days, not equal to 607.6 +/- 136.7 nmol/mg protein). No significant taurocholate active uptake component was noted at 14 days; however, ileal vesicles from sucklings showed carrier-mediated, Na+ D-glucose cotransport. In greater than or equal to 35-day-old rabbits, osmolarity studies at 20 s of incubation showed that only approximately 12% of [14C]taurocholate uptake was secondary to bile acid-to-membrane binding. Conversely, at 20 min, greater than 95% of radiolabel incorporation represented solute bound to the external and/or internal membrane surface. Arrhenius plots establish brush-border membrane taurocholate uptake as an intrinsic, lipid-dependent process, with a slope discontinuity between 24 and 28 degrees C, similar to the membrane lipid thermotropic transition region. Steady-state fluorescence polarization studies (1,6-diphenyl-1,3,5-hexatriene) demonstrate a temporal association between the maturation of taurocholate uptake and age-related decreases in ileal brush-border membrane fluidity. These data indicate that maturation of bile acid secondary active transport in the rabbit ileum may be regulated, at least in part, by changes in brush-border membrane lipid dynamics

  2. Generation of stable lipid raft microdomains in the enterocyte brush border by selective endocytic removal of non-raft membrane.

    Directory of Open Access Journals (Sweden)

    E Michael Danielsen

    Full Text Available The small intestinal brush border has an unusually high proportion of glycolipids which promote the formation of lipid raft microdomains, stabilized by various cross-linking lectins. This unique membrane organization acts to provide physical and chemical stability to the membrane that faces multiple deleterious agents present in the gut lumen, such as bile salts, digestive enzymes of the pancreas, and a plethora of pathogens. In the present work, we studied the constitutive endocytosis from the brush border of cultured jejunal explants of the pig, and the results indicate that this process functions to enrich the contents of lipid raft components in the brush border. The lipophilic fluorescent marker FM, taken up into early endosomes in the terminal web region (TWEEs, was absent from detergent resistant membranes (DRMs, implying an association with non-raft membrane. Furthermore, neither major lipid raft-associated brush border enzymes nor glycolipids were detected by immunofluorescence microscopy in subapical punctae resembling TWEEs. Finally, two model raft lipids, BODIPY-lactosylceramide and BODIPY-GM1, were not endocytosed except when cholera toxin subunit B (CTB was present. In conclusion, we propose that constitutive, selective endocytic removal of non-raft membrane acts as a sorting mechanism to enrich the brush border contents of lipid raft components, such as glycolipids and the major digestive enzymes. This sorting may be energetically driven by changes in membrane curvature when molecules move from a microvillar surface to an endocytic invagination.

  3. Generation of stable lipid raft microdomains in the enterocyte brush border by selective endocytic removal of non-raft membrane.

    Science.gov (United States)

    Danielsen, E Michael; Hansen, Gert H

    2013-01-01

    The small intestinal brush border has an unusually high proportion of glycolipids which promote the formation of lipid raft microdomains, stabilized by various cross-linking lectins. This unique membrane organization acts to provide physical and chemical stability to the membrane that faces multiple deleterious agents present in the gut lumen, such as bile salts, digestive enzymes of the pancreas, and a plethora of pathogens. In the present work, we studied the constitutive endocytosis from the brush border of cultured jejunal explants of the pig, and the results indicate that this process functions to enrich the contents of lipid raft components in the brush border. The lipophilic fluorescent marker FM, taken up into early endosomes in the terminal web region (TWEEs), was absent from detergent resistant membranes (DRMs), implying an association with non-raft membrane. Furthermore, neither major lipid raft-associated brush border enzymes nor glycolipids were detected by immunofluorescence microscopy in subapical punctae resembling TWEEs. Finally, two model raft lipids, BODIPY-lactosylceramide and BODIPY-GM1, were not endocytosed except when cholera toxin subunit B (CTB) was present. In conclusion, we propose that constitutive, selective endocytic removal of non-raft membrane acts as a sorting mechanism to enrich the brush border contents of lipid raft components, such as glycolipids and the major digestive enzymes. This sorting may be energetically driven by changes in membrane curvature when molecules move from a microvillar surface to an endocytic invagination.

  4. Dietary free fatty acids form alkaline phosphatase-enriched microdomains in the intestinal brush border membrane

    DEFF Research Database (Denmark)

    Hansen, Gert H; Rasmussen, Karina; Niels-Christiansen, Lise-Lotte

    2011-01-01

    this membrane passage in organ cultured intestinal mucosal explants. We found that in addition to a rapid uptake into the cytoplasm, a fraction of the fatty acid analogs were inserted directly into the brush border membrane. Furthermore, a brief exposure of microvillar membrane vesicles to a fat mixture...... mimicking a physiological solution of dietary mixed micelles, rearranged the lipid raft microdomain organization of the membranes. Thus, the fat mixture generated a low-density subpopulation of microvillar detergent resistant membranes (DRMs) highly enriched in alkaline phosphatase (AP). Since this GPI-linked...... enzyme is the membrane protein in the brush border with the highest affinity for lipid rafts, this implies that free fatty acids selectively insert stably into these membrane microdomains. We have previously shown that absorption of dietary lipids transiently induce a selective endocytosis of AP from...

  5. Generation of stable lipid raft microdomains in the enterocyte brush border by selective endocytic removal of non-raft membrane

    DEFF Research Database (Denmark)

    Danielsen, E Michael; Hansen, Gert H

    2013-01-01

    The small intestinal brush border has an unusually high proportion of glycolipids which promote the formation of lipid raft microdomains, stabilized by various cross-linking lectins. This unique membrane organization acts to provide physical and chemical stability to the membrane that faces...... functions to enrich the contents of lipid raft components in the brush border. The lipophilic fluorescent marker FM, taken up into early endosomes in the terminal web region (TWEEs), was absent from detergent resistant membranes (DRMs), implying an association with non-raft membrane. Furthermore, neither...... major lipid raft-associated brush border enzymes nor glycolipids were detected by immunofluorescence microscopy in subapical punctae resembling TWEEs. Finally, two model raft lipids, BODIPY-lactosylceramide and BODIPY-GM1, were not endocytosed except when cholera toxin subunit B (CTB) was present...

  6. Probing endocytosis from the enterocyte brush border using fluorescent lipophilic dyes

    DEFF Research Database (Denmark)

    Danielsen, E Michael

    2015-01-01

    The small intestinal brush border is a specialized cell membrane that needs to withstand the solubilizing effect of bile salts during assimilation of dietary nutrients and to achieve detergent resistance; it is highly enriched in glycolipids organized in lipid raft microdomains. In the present work......-toluenesulfonate), and CellMask Orange plasma membrane stain were used to study endocytosis from the enterocyte brush border of organ-cultured porcine mucosal explants. All the dyes readily incorporated into the brush border but were not detectably endocytosed by 5 min, indicating a slow uptake compared with other cell types...

  7. A photoactivatable probe for the Na+/H+ exchanger cross-links a 66-kDa renal brush border membrane protein

    International Nuclear Information System (INIS)

    Ross, W.; Bertrand, W.; Morrison, A.

    1990-01-01

    Earlier studies on LLC-PK1 cells have demonstrated two pharmacologically distinct Na+/H+ exchangers in renal epithelia. In addition, the cDNA clone for the human Na+/H+ antiporter which is growth factor activatable has been isolated and expressed. We report here the synthesis of an amiloride analogue that can be photoactivated and labeled with 125I. This analogue covalently cross-links a 66-kDa protein of bovine renal brush border membranes. A rabbit polyclonal antibody that was directed against a 20-amino acid peptide of the cytoplasmic domain of its human Na+/H+ antiporter also gives a positive Western against 66-kDa protein of bovine brush border membranes. Thus, the photoactive probe may be helpful in the isolation and purification of the brush border Na+/H+ exchanger

  8. Changes in intestinal absorption of nutrients and brush border glycoproteins after total parenteral nutrition in rats.

    Science.gov (United States)

    Miura, S; Tanaka, S; Yoshioka, M; Serizawa, H; Tashiro, H; Shiozaki, H; Imaeda, H; Tsuchiya, M

    1992-01-01

    The effect of total parenteral nutrition on nutrients absorption and glycoprotein changes of brush border membrane was examined in rat small intestine. In total parenteral nutrition rats, a marked decrease in activity of brush border enzymes was observed mainly in the proximal and middle segments of the intestine. Galactose perfusion of jejunal segment showed that hexose absorption was significantly inhibited, while intestinal absorption of glycine or dipeptide, glycylglycine was not significantly affected by total parenteral nutrition treatment. When brush border membrane glycoprotein profile was examined by [3H]-glucosamine or [3H]-fucose incorporation into jejunal loops, significant changes were observed in the glycoprotein pattern of brush border membrane especially in the high molecular weight range over 120 kDa after total parenteral nutrition treatment, suggesting strong dependency of glycoprotein synthesis on luminal substances. Molecular weight of sucrase isomaltase in brush border membrane detected by specific antibody showed no significant difference, however, in total parenteral nutrition and control rats. Also, molecular weight of specific sodium glucose cotransporter of intestinal brush border membrane detected by selective photoaffinity labelling was not altered in total parenteral nutrition rats. It may be that prolonged absence of oral food intake may produce significant biochemical changes in brush border membrane glycoprotein and absorptive capacity of small intestine, but these changes were not observed in all brush border membrane glycoproteins. Images Figure 1 Figure 2 Figure 3 Figure 4 PMID:1582592

  9. Inhibition of beta-amino acid transport by diamide does not involve the brush border membrane surface

    International Nuclear Information System (INIS)

    Chesney, R.W.; Gusowski, N.; Albright, P.

    1985-01-01

    Diamide (dicarboxylic acid bis-(N,N-dimethylamide) has been shown in previous studies to block the uptake of the beta-amino acid taurine at its high affinity transport site in rat renal cortex slices. Diamide may act by increasing the efflux of taurine from the slice. Studies performed in rat slices again indicate enhanced efflux over 8-12 minutes. The time course of reduced glutathione (GSH) depletion from renal cortex is similar, indicating a potential interaction between GSH depletion and inhibition of taurine accumulation. The effect of 9 mM diamide on the Na+ -dependent accumulation of taurine (10 and 250 microM) by brush border membrane vesicles was examined, and the taurine uptake value both initially and at equilibrium was the same in the presence and absence of diamide. Isolation of the brush border surface and subsequent transport studies of taurine are not influenced by diamide. Thus, diamide inhibition of taurine uptake does not involve physiochemical alteration of the membrane surface where active amino acid transport occurs, despite the thiol-oxidizing properties of this agent. Further, these studies suggest that diamide either acts at the basolateral surface, rather than the brush border surface of rat renal cortex or requires the presence of an intact tubule, capable of metabolism, prior to its inhibitory action

  10. Galectin-4 and small intestinal brush border enzymes form clusters

    DEFF Research Database (Denmark)

    Danielsen, E M; van Deurs, B

    1997-01-01

    that galectin-4 is indeed an intestinal brush border protein; we also localized galectin-4 throughout the cell, mainly associated with membraneous structures, including small vesicles, and to the rootlets of microvillar actin filaments. This was confirmed by subcellular fractionation, showing about half...... by a nonclassical pathway, and the brush border enzymes represent a novel class of natural ligands for a member of the galectin family. Newly synthesized galectin-4 is rapidly "trapped" by association with intracellular structures prior to its apical secretion, but once externalized, association with brush border......Detergent-insoluble complexes prepared from pig small intestine are highly enriched in several transmembrane brush border enzymes including aminopeptidase N and sucrase-isomaltase, indicating that they reside in a glycolipid-rich environment in vivo. In the present work galectin-4, an animal lectin...

  11. Endocytic trafficking from the small intestinal brush border probed with FM dye

    DEFF Research Database (Denmark)

    Hansen, Gert H; Rasmussen, Karina; Niels-Christiansen, Lise-Lotte

    2009-01-01

    -linking galectins/intelectin, but little is known about the dynamic properties of this highly specialized membrane. Here, we probed the endocytic membrane trafficking from the brush border of organ cultured pig intestinal mucosal explants by use of a fixable, lipophilic FM dye. The fluorescent dye readily......, contributes to the overall permeability barrier of the gut. Key words: FM dye, small intestine, brush border, endocytosis....

  12. Dimeric assembly of enterocyte brush border enzymes

    DEFF Research Database (Denmark)

    Danielsen, E M

    1994-01-01

    The noncovalent, dimeric assembly of small intestinal brush border enzymes was studied by sedimentation analysis in density gradients of extracts of pulse-labeled pig jejunal mucosal explants. Like aminopeptidase N (EC 3.4.11.2), sucrase-isomaltase (EC 3.2.1.48-10), aminopeptidase A (EC 3...... appearance of the liposome-reconstituted enzyme [Norén et al. (1986) J. Biol. Chem. 261, 12306-12309], showing only the inner, membrane-anchored domains of the monomers to be in close contact with one another while the outer domains are far apart. In contrast to the other brush border enzymes studied...

  13. Sulfate uptake by crustacean hepatopancreatic brush border membrane vesicles

    International Nuclear Information System (INIS)

    Gerencser, G.A.; Cattey, M.A; Ahearn, G.A.

    1990-01-01

    Purified brush border membrane vesicles (BBMV) were prepared from Atlantic lobster (Homarus americanus) hepatopancreas using differential centrifugation and Mg +2 precipitation techniques. Uptake of 0.1 mM 35 SO 4 -2 was stimulated by pre-loading vesicles with Cl - leading to a transient accumulation of isotope more than twice that at equilibrium. Pre-loading with HCO 3 - or gluconate had no effect on sulfate uptake. No stimulation of 35 SO 4 -2 was observed in the presence of inwardly directed Na + or tetramethylammonium + gradients. Uptake of the divalent anion was strongly stimulated by inwardly directed proton gradients (pH o i ) and markedly inhibited by outwardly directed proton gradients (pH o > pH i ). 35 SO 4 -2 /Cl - exchange was enhanced by imposing a transmembrane inside positive K + diffusion potential and inhibited by a membrane potential of the opposite polarity (K + /valinomycin). Results suggest the presence of a proton-dependent, electrogenic anion antiport mechanism in BBMV isolated from the crustacean hepatopancreas

  14. Uptake of 75Se-selenite by brush border membrane vesicles from chick duodenum stimulated by vitamin D

    International Nuclear Information System (INIS)

    Mykkanen, H.M.; Wasserman, R.H.

    1989-01-01

    Brush border membrane vesicles were isolated from mucosal homogenates of duodena from normal, rachitic and vitamin D-treated rachitic chicks using a discontinuous sucrose gradient, and further purified by glycerol gradient centrifugation. In vitro uptake of 75Se-selenite by purified brush border membrane vesicles was studied using a rapid filtration technique. The time course of 75Se uptake was non-linear; rapid initial binding was followed by a gradual decrease in the rate of uptake until an equilibrium value was reached at 60-120 min. The initial binding at 36 s was not affected by selenite concentration in the incubation buffer, while the fractional rate of uptake between the 36 s and 2 min time periods was clearly lower with 1 mM Se than with 4-100 microM Se. 75Se uptake did not show any dependency on the external Na-gradient, nor could it be inhibited by other anions (arsenate, phosphate). Treatment of rachitic chicks either with cholecalciferol (500 Iu, 72 h) or with 1,25(OH)2-cholecalciferol (0.5 microgram given 16 h prior to isolation of the vesicles) significantly enhanced 75Se uptake. A threefold excess of mannitol in the outside buffer reduced 75Se uptake by vesicles from vitamin D-deficient and D-treated chicks 60% and 35% respectively, but had no effect on vesicles from vitamin D-treated chicks preloaded with 75Se. Neither saponin treatment nor excess cold selenite could release the label from the vesicles preloaded with 75Se. These data are compatible with the hypothesis that selenite easily crosses the brush border membrane into the intravesicular space and, once inside, is tightly bound by the membrane

  15. Native proteomic analysis of protein complexes in murine intestinal brush border membranes

    Czech Academy of Sciences Publication Activity Database

    Babušiak, M.; Man, Petr; Petrák, J.; Vyoral, D.

    2007-01-01

    Roč. 7, č. 1 (2007), s. 121-129 ISSN 1615-9853 R&D Projects: GA ČR(CZ) GD204/03/H066; GA AV ČR KJB500200612; GA MŠk LC545 Grant - others:GA ČR(CZ) GA303/04/0003; GA MZd(CZ) NR8930; GA MŠk(CZ) LC06044; CZ(CZ) 023736; GA MZd(CZ) NR8317 Program:NR Institutional research plan: CEZ:AV0Z50200510 Keywords : blue native electrophoresis * brush border membranes * protein complexes Subject RIV: EE - Microbiology, Virology Impact factor: 5.479, year: 2007

  16. H+ V-ATPase-Energized Transporters in Brush Border Membrane Vesicles from Whole Larvae of Aedes Aegypti

    Science.gov (United States)

    Brush Border Membrane vesicles (BBMVs) from Whole larvae of Aedes aegypti (AeBBMVWs ) contain an H+ V-ATPase (V), a Na+/H+ antiporter, NHA1 (A) and a Na+-coupled, nutrient amino acid transporter, NAT8 (N), VAN for short. All V-ATPase subunits are present in the Ae. aegypti genome and in the vesicles...

  17. Immunoelectrophoretic studies on pig intestinal brush border proteins

    DEFF Research Database (Denmark)

    Danielsen, Erik Michael; Sjöström, H; Norén, O

    1977-01-01

    Brush borders were prepared from pig intestinal mucosa and the membrane proteins solubilized with either Triton X-100 or papain. Proteins, thus released, were used as antigens to raise antisera in rabbits. The immunoglobulin G fractions were isolated and shown by the double layer immunofluorescence...

  18. Deep-apical tubules: dynamic lipid-raft microdomains in the brush-border region of enterocytes

    DEFF Research Database (Denmark)

    Hansen, Gert H; Pedersen, Jens; Niels-Christiansen, Lise-Lotte

    2003-01-01

    microdomains. Deep-apical tubules were positioned close to the actin rootlets of adjacent microvilli in the terminal web region, which had a diameter of 50-100 nm, and penetrated up to 1 microm into the cytoplasm. Markers for transcytosis, IgA and the polymeric immunoglobulin receptor, as well as the resident...... lipid raft-containing compartments, but little is otherwise known about these raft microdomains. We therefore studied in closer detail apical lipid-raft compartments in enterocytes by immunogold electron microscopy and biochemical analyses. Novel membrane structures, deep-apical tubules, were visualized...... brush-border enzyme aminopeptidase N, were present in these deep-apical tubules. We propose that deep-apical tubules are a specialized lipid-raft microdomain in the brush-border region functioning as a hub in membrane trafficking at the brush border. In addition, the sensitivity to cholesterol depletion...

  19. Lipid rafts exist as stable cholesterol-independent microdomains in the brush border membrane of enterocytes

    DEFF Research Database (Denmark)

    Hansen, Gert Helge; Immerdal, Lissi; Thorsen, Evy

    2001-01-01

    Glycosphingolipid/cholesterol-rich membranes ("rafts")can be isolated from many types of cells, but their existence as stable microdomains in the cell membrane has been elusive. Addressing this problem, we studied the distribution of galectin-4, a raft marker, and lactase, a protein excluded from...... rafts, on microvillar vesicles from the enterocyte brush border membrane. Magnetic beads coated with either anti-galectin-4 or anti-lactase antibodies were used for immunoisolation of vesicles followed by double immunogold labeling of the two proteins. A morphometric analysis revealed subpopulations...... of raft-rich and raft-poor vesicles by the following criteria: 1) the lactase/galectin-4 labeling ratio/vesicle captured by the anti-lactase beads was significantly higher (p

  20. Bile salt-induced increases in duodenal brush-border membrane proton permeability, fluidity, and fragility

    International Nuclear Information System (INIS)

    Zhao, D.L.; Hirst, B.H.

    1990-01-01

    Rabbit duodenal brush-border membrane vesicles were treated in vitro with deoxycholate, glycodeoxycholate, or taurodeoxycholate. Intravesicular [14C]glucose space at equilibrium, 0.54 microliters/mg protein, was reduced by exposure to the three bile salts in a concentration (0.1-5.0 mM)-dependent manner, equatable with increased membrane fragility. Net proton permeability (Pnet), determined by acridine orange fluorescence quenching, was increased from 6.3 x 10(-4) cm/sec in untreated vesicles, by approximately 120, 150, and 170%, by treatment with bile salts at 0.1, 0.5 and 1.0 mM, respectively. The three bile salts were equipotent. The increases in membrane fragility and Pnet were not accompanied by significant increases in membrane fluidity, as assessed from steady-state and time-resolved diphenylhexatriene fluorescence anisotropy. The data demonstrate direct effects of bile salts on duodenal apical membrane fragility and proton permeability that are likely to be early events in bile salt-induced mucosal damage

  1. Faecal excretion of brush border membrane enzymes in patients with clostridium difficile diarrhoea

    Directory of Open Access Journals (Sweden)

    Katyal R

    2002-01-01

    Full Text Available PURPOSE: To look for the presence of intestinal brush border membrane (BBM enzymes in the faecal samples of patients with Clostridium difficile association. METHODS: One hundred faecal samples were investigated for C.difficile toxin (CDT. Simultaneous assays for faecal excretion of intestinal BBM enzymes viz., disaccharidases, alkaline phosphatase (AP and leucine aminopeptidase (LAP were also done. RESULTS: C.difficile toxin was detected in 25 (25% of the samples with a titre ranging from 10 to 160. No significant difference (p>0.05 was seen between the CDT positive and negative groups with any of the disaccharidases studied. However, significant increase (pC.difficile diarrhoea.

  2. Involvement of detergent-insoluble complexes in the intracellular transport of intestinal brush border enzymes

    DEFF Research Database (Denmark)

    Danielsen, E M

    1995-01-01

    A number of transmembrane digestive enzymes of the porcine small intestinal brush border membrane were found to be partially Triton X-100-insoluble at 0 degree C and colocalized in gradient centrifugation experiments with the GPI-anchored alkaline phosphatase in low-density, detergent-insoluble c...... intracellularly. I therefore propose that, in the enterocyte, the brush border enzymes are targeted directly from the trans-Golgi network toward the apical cell surface......., and their insolubility increased to that of the steady-state level soon after they achieved their mature, complex glycosylation, i.e., after passage through the Golgi complex. Detergent-insoluble complexes isolated by density gradient centrifugation were highly enriched in brush border enzymes, and the enrichment...

  3. Library of monoclonal antibodies against brush border membrane epithelial antigens

    International Nuclear Information System (INIS)

    Behar, M.; Katz, A.; Silverman, M.

    1986-01-01

    A purified fraction of proximal tubule brush border membranes (BBM) was prepared from dog kidney and used to immunize mice. The standard technique of hybridoma production was followed as described by Kohler and Milstein. Production of antibodies was detected by indirect immunofluorescence on dog kidney slices and by immunodot against the purified fraction on nitrocellulose. Five hybrids exhibited anti BBM activity. These were cloned twice and yielded stable cell lines producing IgG type monoclonal antibodies against BBM. They were designated A 1 , C 7 , D 3 , D 7 and H 4 . As a family these five monoclonals have broad tissue specificity, i.e. positive staining of the surface mucosa of intestinal kidney proximal tubules. D 3 exhibits even broader specificity for epithelium reacting with bile canaliculi and choroid plexus. The authors have verified that at least 4/5 antibodies are directed against BBM protein as revealed by immunoprecipitation of solubilized BBM and detected by Coomassie blue staining or autoradiography of lactoperoxidase labelled BBM. Most interestingly all antibodies bind to the surface of LL CPK 1 cells, a continuous pig kidney cell line of undefined origin but exhibiting many characteristics of proximal tubule cells. The library of monoclonal antibodies obtained provide important probes with which to study membrane biogenesis and polarization in epithelial cells

  4. Transport of acidic amino acids by human jejunal brush-border membrane vesicles

    International Nuclear Information System (INIS)

    Rajendran, V.M.; Harig, J.M.; Adams, M.B.; Ramaswamy, K.

    1987-01-01

    This study characterizes the transport of radiolabeled acidic amino acids into brush-border membrane vesicles prepared from human jejunum. The uptakes of L-glutamic, L-aspartic, and D-aspartic acids were stimulated by a Na + gradient. Concentrative uptake (resulting in an overshoot phenomenon) of these dicarboxylic amino acids occurred when there was an outward K + gradient. In addition, increasing K + gradients resulted in enhanced uptake of L-glutamic acid. This K + requirement is somewhat specific as Rb + and Cs + could enhance uptake to a limited extent, whereas Li + and choline + showed no enhancement. The presence of a K + gradient did not affect the affinity of the carrier system for L-glutamic acid but it did increase the V/sub max/. The presence of extravesicular anions having differing membrane permeabilities did not altar L-glutamic acid uptake indicating an absence of an effect of membrane potential on the transport process. Finally, the human transport system for L-glutamic acid appears to be specific for acidic amino acids as demonstrated by inhibition studies. The studies demonstrate a transport system in human jejunum specific for acidic amino acids that is energized by an inward Na + gradient and an outward K + gradient

  5. The Secretion and Action of Brush Border Enzymes in the Mammalian Small Intestine.

    Science.gov (United States)

    Hooton, Diane; Lentle, Roger; Monro, John; Wickham, Martin; Simpson, Robert

    2015-01-01

    Microvilli are conventionally regarded as an extension of the small intestinal absorptive surface, but they are also, as latterly discovered, a launching pad for brush border digestive enzymes. Recent work has demonstrated that motor elements of the microvillus cytoskeleton operate to displace the apical membrane toward the apex of the microvillus, where it vesiculates and is shed into the periapical space. Catalytically active brush border digestive enzymes remain incorporated within the membranes of these vesicles, which shifts the site of BB digestion from the surface of the enterocyte to the periapical space. This process enables nutrient hydrolysis to occur adjacent to the membrane in a pre-absorptive step. The characterization of BB digestive enzymes is influenced by the way in which these enzymes are anchored to the apical membranes of microvilli, their subsequent shedding in membrane vesicles, and their differing susceptibilities to cleavage from the component membranes. In addition, the presence of active intracellular components of these enzymes complicates their quantitative assay and the elucidation of their dynamics. This review summarizes the ontogeny and regulation of BB digestive enzymes and what is known of their kinetics and their action in the peripheral and axial regions of the small intestinal lumen.

  6. (Na+ + K+)-ATPase and plasma membrane polarity of intestinal epithelial cells: Presence of a brush border antigen in the distal large intestine that is immunologically related to beta subunit

    Energy Technology Data Exchange (ETDEWEB)

    Marxer, A.; Stieger, B.; Quaroni, A.; Kashgarian, M.; Hauri, H.P. (Univ. of Basel (Switzerland))

    1989-09-01

    The previously produced monoclonal antibody IEC 1/48 against cultured rat intestinal crypt cells was extensively characterized and found to be directed against the beta subunit of (Na+ + K+)-ATPase as assessed by immunological and enzymatic criteria. Under nondenaturing conditions the antibody precipitated the alpha-beta enzyme complex (98,000 and 48,000 Mr). This probe, together with the monoclonal antibody C 62.4 against the alpha subunit was used to localize (Na+ + K+)-ATPase in epithelial cells along the rat intestinal tract by immunofluorescence and immunoelectron microscopy. Both antibodies exclusively labeled the basolateral membrane of small intestine and proximal colon epithelial cells. However, in the distal colon, IEC 1/48, but not C 62.4, also labeled the brush border membrane. The cross-reacting beta-subunit-like antigen on the apical cell pole was tightly associated with isolated brush borders but was apparently devoid of (Na+ + K+)-ATPase activity. Subcellular fractionation of colonocytes in conjunction with limited proteolysis and surface radioiodination of intestinal segments suggested that the cross-reacting antigen in the brush border may be very similar to the beta subunit. The results support the notion that in the small intestine and proximal colon the enzyme subunits are exclusively targeted to the basolateral membrane while in the distal colon nonassembled beta subunit or a beta-subunit-like protein is also transported to the apical cell pole.

  7. Galectin-2 at the enterocyte brush border of the small intestine

    DEFF Research Database (Denmark)

    Thomsen, Martha Kampp; Hansen, Gert H; Danielsen, E Michael

    2009-01-01

    boundary. Together with the membrane glycolipids these lectins form stable lipid raft microdomains that also harbour several of the major digestive microvillar enzymes. In the present work, we identified a lactose-sensitive 14-kDa protein enriched in a microvillar detergent resistant fraction as galectin-2....... Its release from closed, right-side-out microvillar membrane vesicles shows that at least some of the galectin-2 resides at the lumenal surface of the brush border, indicating that it plays a role in the organization/stabilization of the lipid raft domains. Galectin-2 was released more effectively...

  8. Isolation and partial characterization of gypsy moth BTR-270, an anionic brush border membrane glycoconjugate that binds Bacillus thuringiensis Cry1A toxins with high affinity

    Science.gov (United States)

    Algimantas P. Valaitis; Jeremy L. Jenkins; Mi Kyong Lee; Donald H. Dean; Karen J. Garner

    2001-01-01

    BTR-270, a gypsy moth (Lymantria dispar) brush border membrane molecule that binds Bacillus thuringiensis (Bt) Cry1A toxins with high affinity, was purified by preparative gel electrophoresis. Rabbit antibodies specific for the Bt toxin-binding molecule were raised. Attempts to label BTR-270 by protein-directed techniques were...

  9. Association and dissociation of Escherichia coli heat-stable enterotoxin from rat brush border membrane receptors

    International Nuclear Information System (INIS)

    Cohen, M.B.; Thompson, M.R.; Overmann, G.J.; Giannella, R.A.

    1987-01-01

    Escherichia coli heat-stable enterotoxin (ST) binds to receptors on rat intestinal cells and brush border membranes (BBM). We devised experiments to examine the reversibility of ST binding. We found that both 125 I-labeled ST and native ST were spontaneously dissociable from the BBM receptor. Radiolabeled ST bound to BBM was also dissociated by the addition of avid goat anti-ST antiserum. Furthermore, using a computer program for analysis of ligand binding, we calculated an apparent Ka of 10(8) liters/mol from competitive inhibition and saturation-binding data. This is significantly lower than the value previously reported by others. Our findings, of a lower Ka and a reversible ST-binding process, suggest that a therapeutic strategy of removing bound ST from its receptor or competing with the enterocyte receptor for unbound ST might be successful in terminating ST-induced secretion

  10. Zinc uptake in swine intestinal brush border membrane vesicles using a 65Zn/69mZn duel isotope experiment

    International Nuclear Information System (INIS)

    Huntington, C.E.; Morris, J.S.; Veum, T.L.

    2008-01-01

    Supplemental zinc as ZnO is routinely added to nursery pig diets at 15 to 20 times the nutritional requirement to alleviate physiological stress and enhance performance. The mechanism by which Zn accomplishes this function is unknown, however, high concentrations of Zn are excreted in the environment at undesirable levels. To study Zn uptake, we developed a multi-stage digestion model followed by exposure to swine intestinal brush border membrane vesicles (BBMV). We report on the feasibility of using a duel label ( 65 Zn and 69m Zn) to simultaneously quantify the competitive uptake of Zn from co-existing zinc supplements using our BBMV model. (author)

  11. Nephrotoxicity of uranyl acetate: effect on rat kidney brush border membrane vesicles

    International Nuclear Information System (INIS)

    Goldman, M.; Yaari, A.; Moran, A.; Doshnitzki, Z.; Cohen-Luria, R.

    2006-01-01

    Since the Gulf war exposure to depleted uranium, a known nephrotoxic agent, there is a renewed interest in the toxic effects of uranium in general and its mechanism of nephrotoxicity which is still largely unknown in particular. In order to investigate the mechanism responsible for uranium nephrotoxicity and the therapeutic effect of urine alkalization, we utilized rat renal brush border membrane vesicles (BBMV). Uranyl acetate (UA) caused a decrease in glucose transport in BBMV. The apparent K i of uranyl was 139±30 μg uranyl/mg protein of BBMV. Uranyl at 140 μg/mg protein of BBMV reduced the maximal capacity of the system to transport glucose [V max 2.2±0.2 and 0.96±0.16 nmol/mg protein for control and uranyl treated BBMV (P m (1.54±0.33 and 1.54±0.51 mM for control, and uranyl treated BBMV, respectively). This reduction in V max is at least partially due to a decrease in the number of sodium-coupled glucose transporters as apparent from the reduction in phlorizin binding to the uranyl treated membranes, V max was reduced from 247±13 pmol/mg protein in control BBMV to 119±3 pmol/mg protein in treated vesicles (P<0.001). The pH of the medium has a profound effect on the toxicity of UA on sodium-coupled glucose transport in BBMV: higher toxicity at neutral pH (around pH 7.0), and practically no toxicity at alkaline pH (7.6). This is the first report showing a direct inhibitory dose and pH dependent effect of uranyl on the glucose transport system in isolated apical membrane from kidney cortex. (orig.)

  12. Specificity of Bacillus thuringiensis endotoxins is correlated with the presence of high-affinity binding sites in the brush border membrane of target insect midguts

    International Nuclear Information System (INIS)

    Hofmann, C.; Vanderbruggen, H.; Hoefte, H.; Van Rie, J.; Jansens, S.; Van Mellaert, H.

    1988-01-01

    Binding studies were performed with two 125 I-labeled Bacillus thuringiensis δ-endotoxins on brush border membrane vesicles prepared from the larval midgut of the tobacco hornworm Manduca sexta or the cabbage butterfly Pieris brassicae. One δ-endotoxin, Bt2-protoxin, is a 130-kDa recombinant crystalline protein from B. thuringiensis subsp. berliner. It kills larvae of both insect species. The active Bt2-toxin is a 60-kDa proteolytic fragment of the Bt2-protoxin. It binds saturably and with high affinity to brush border membrane vesicles from the midgut of both species. The other δ-endotoxin, Bt4412-protoxin, is a 136-kDa crystalline protein from B. thuringiensis subsp. thuringiensis, which is highly toxic for P. brassicae, but not for M. sexta larvae. Bt4412-toxin, obtained after proteolytic activation of Bt4412-protoxin, shows high-affinity saturable binding to P. brassicae vesicles but not to M. sexta vesicles. The correlation between toxicity and specific binding is further strengthened by competition studies. Other B. thuringiensis δ-endotoxins active against M. sexta compete for binding of 125 I-labeled Bt2-toxin to M. sexta vesicles, whereas toxins active against dipteran or coleopteran larvae do not compete. Bt2-toxin and Bt4412-toxin bind to different sites on P. brassicae vesicles

  13. Intestinal alkaline phosphatase: selective endocytosis from the enterocyte brush border during fat absorption

    DEFF Research Database (Denmark)

    Hansen, Gert Helge; Niels-Christiansen, Lise-Lotte; Immerdal, Lissi

    2007-01-01

    explants. By immunofluorescence microscopy, fat absorption caused a translocation of IAP from the enterocyte brush border to the interior of the cell, whereas other brush-border enzymes were unaffected. By electron microscopy, the translocation occurred by a rapid (5 min) induction of endocytosis via...

  14. Mechanism of cis- and trans-substrate interactions at the tetraethylammonium/H+ exchanger of rabbit renal brush-border membrane vesicles

    International Nuclear Information System (INIS)

    Wright, S.H.; Wunz, T.M.

    1988-01-01

    The kinetic basis for trans-effects of intravesicular substrates on the uptake of the organic cation, tetraethylammonium (TEA), into rabbit renal brush-border membrane vesicles (BBMV) was studied. Preloading BBMV with 1, 2, or 4 mM TEA stimulated the initial rate of uptake and the total net accumulation of 0.1 mM [ 3 H]TEA. The stimulatory effect of intravesicular TEA on the initial rate of uptake was a saturable function of the trans-TEA concentration, with a half-maximal effect noted at an intravesicular concentration of 0.28 mM. A 1 mM trans-concentration of TEA increased the Jmax of [ 3 H]TEA uptake (from 4.3 to 6.8 nmol.mg-1.min-1) without affecting the apparent Kt. An outwardly directed H+ gradient also increased Jmax (to 10.7 nmol.mg-1.min-1), although the addition of an outwardly directed TEA gradient did not produce further increases in the rate of TEA uptake. External H+ acted as a competitive inhibitor of TEA uptake, and an increase in external [H+] (from 32 nM to 100 nM) produced an increase in the apparent Kt for TEA transport (from 0.12 to 0.26 mM) without affecting the Jmax. The results suggested that TEA and H+ compete for a common site or set of mutually exclusive sites on the cytoplasmic and luminal aspects of TEA/H+ exchanger in the renal brush border, and that these sites have a similar affinity for TEA

  15. Effect of alpha interferon on glucose and alanine transport by rat renal brush border membrane vesicles

    International Nuclear Information System (INIS)

    Batuman, V.; Chadha, I.

    1990-01-01

    To investigate the pathogenetic mechanisms of interferon nephrotoxicity, we studied the effect of recombinant interferon alfa-2b on the uptake of 14 C-D-glucose and 14 C-L-alanine by rat renal brush-border-membrane vesicles. Interferon significantly inhibited 20 sec. sodium-dependent and 5 and 10 min. equilibrium uptake of both glucose and alanine. The inhibitory effect was dose dependent with maximum effect achieved at interferon concentration of 5 x 10 -8 M in the uptake media. The half-maximal inhibitory concentrations, IC 50 , of interferon on glucose uptake was 1.8 x 10 -8 M, and 5.4 x 10 -9 M on alanine uptake. Dixon plot analysis of uptake data was consistent with pure non-competitive inhibition. The inhibition constants, K i , 1.5 x 10 -8 M for glucose uptake, and 7.3 x 10 -9 M for alanine uptake, derived from Dixon plots were in close agreement with the IC 50 s calculated from the semilog dose response curves. These observations reveal that direct interactions at the proximal tubule cell membrane are involved in the pathogenesis of interferon nephrotoxicity, and that its mechanism of nephrotoxicity is similar to that of other low molecular weight proteins

  16. Post-translational suppression of expression of intestinal brush border enzymes by fructose

    DEFF Research Database (Denmark)

    Danielsen, E M

    1989-01-01

    The two major dietary sugars, fructose and sucrose, were found to suppress effectively the biosynthetic renewal of brush border enzymes in the gut. When studied in cultured explants of pig small intestine mucosa, 10-50 mM concentrations of fructose completely prevented the expression of mature...... cotranslational glycosylation that in turn triggers a rapid proteolytic breakdown. Our findings suggest that renewal of digestive brush border enzymes is transiently suppressed during intake of fructose- or sucrose-rich meals....

  17. A Tenebrio molitor GPI-anchored alkaline phosphatase is involved in binding of Bacillus thuringiensis Cry3Aa to brush border membrane vesicles.

    Science.gov (United States)

    Zúñiga-Navarrete, Fernando; Gómez, Isabel; Peña, Guadalupe; Bravo, Alejandra; Soberón, Mario

    2013-03-01

    Bacillus thuringiensis Cry toxins recognizes their target cells in part by the binding to glycosyl-phosphatidyl-inositol (GPI) anchored proteins such as aminopeptidase-N (APN) or alkaline phosphatases (ALP). Treatment of Tenebrio molitor brush border membrane vesicles (BBMV) with phospholipase C that cleaves out GPI-anchored proteins from the membranes, showed that GPI-anchored proteins are involved in binding of Cry3Aa toxin to BBMV. A 68 kDa GPI-anchored ALP was shown to bind Cry3Aa by toxin overlay assays. The 68 kDa GPI-anchored ALP was preferentially expressed in early instar larvae in comparison to late instar larvae. Our work shows for the first time that GPI-anchored ALP is important for Cry3Aa binding to T. molitor BBMV suggesting that the mode of action of Cry toxins is conserved in different insect orders. Copyright © 2012 Elsevier Inc. All rights reserved.

  18. Proline transport by brush-border membrane vesicles of lobster antennal glands

    International Nuclear Information System (INIS)

    Behnke, R.D.; Wong, R.K.; Huse, S.M.; Reshkin, S.J.; Ahearn, G.A.

    1990-01-01

    Purified brush-border membrane vesicles (BBMV) of lobster antennal gland labyrinth and bladder were separately formed by a magnesium precipitation technique. L-[3H]proline uptake was stimulated by a transmembrane NaCl gradient [outside (o) greater than inside (i)] to a greater extent in BBMV from labyrinth than those from the bladder. Detailed study of the labyrinth proline-transport processes revealed a specific dependence on NaCl, with negligible stimulatory effects by NaSCN, Na-gluconate, or KCl. A transmembrane proton gradient (o greater than i) was without stimulatory effect on proline transport. A transmembrane potential difference alone, in the presence of equilibrated NaCl and L-[3H]proline, led to net influx of the labeled amino acid, suggesting that the uptake process was electrogenic and capable of bringing about the net transfer of positive charge to the vesicle interior. Although a transmembrane Na gradient alone, in the presence of equilibrated Cl and L-[3H]proline, was able to bring about the net influx of the amino acid, a transmembrane Cl gradient alone under Na- and L-[3H]proline-equilibrated conditions was not, suggesting that only the Na gradient could energize the carrier process through cotransport, while the anion served an essential activating role. Proline influx by these vesicles occurred by the combination of at least one saturable Michaelis-Menten carrier system (apparent Kt = 0.37 mM; apparent JM = 1.19 nmol.mg protein-1.10 s-1) and apparent diffusion (P = 0.33 nmol.mg protein-1.10 s-1.mM-1). Static head analysis of the transport process suggested a cotransport stoichiometry of 2 Na:1 proline with essential activation by Cl ion

  19. Rotavirus NSP4114-135 peptide has no direct, specific effect on chloride transport in rabbit brush-border membrane

    Directory of Open Access Journals (Sweden)

    Vasseur Monique

    2006-11-01

    Full Text Available Abstract The direct effect of the rotavirus NSP4114-135 and Norovirus NV464-483 peptides on 36Cl uptake was studied by using villus cell brush border membrane (BBM isolated from young rabbits. Both peptides inhibited the Cl-/H+ symport activity about equally and partially. The interaction involved one peptide-binding site per carrier unit. Whereas in vitro NSP4114-135 caused nonspecific inhibition of the Cl-/H+ symporter, the situation in vivo is different. Because rotavirus infection in young rabbits accelerated both Cl- influx and Cl- efflux rates across villi BBM without stimulating Cl- transport in crypt BBM, we conclude that the NSP4114-135 peptide, which causes diarrhea in young rodents, did not have any direct, specific effect on either intestinal absorption or secretion of chloride. The lack of direct effect of NSP4 on chloride transport strengthens the hypothesis that NSP4 would trigger signal transduction pathways to enhance net chloride secretion at the onset of rotavirus diarrhea.

  20. Differential association of the Na+/H+ Exchanger Regulatory Factor (NHERF) family of adaptor proteins with the raft- and the non-raft brush border membrane fractions of NHE3.

    Science.gov (United States)

    Sultan, Ayesha; Luo, Min; Yu, Qin; Riederer, Brigitte; Xia, Weiliang; Chen, Mingmin; Lissner, Simone; Gessner, Johannes E; Donowitz, Mark; Yun, C Chris; deJonge, Hugo; Lamprecht, Georg; Seidler, Ursula

    2013-01-01

    Trafficking, brush border membrane (BBM) retention, and signal-specific regulation of the Na+/H+ exchanger NHE3 is regulated by the Na+/H+ Exchanger Regulatory Factor (NHERF) family of PDZ-adaptor proteins, which enable the formation of multiprotein complexes. It is unclear, however, what determines signal specificity of these NHERFs. Thus, we studied the association of NHE3, NHERF1 (EBP50), NHERF2 (E3KARP), and NHERF3 (PDZK1) with lipid rafts in murine small intestinal BBM. Detergent resistant membranes ("lipid rafts") were isolated by floatation of Triton X-incubated small intestinal BBM from a variety of knockout mouse strains in an Optiprep step gradient. Acid-activated NHE3 activity was measured fluorometrically in BCECF-loaded microdissected villi, or by assessment of CO2/HCO3(-) mediated increase in fluid absorption in perfused jejunal loops of anethetized mice. NHE3 was found to partially associate with lipid rafts in the native BBM, and NHE3 raft association had an impact on NHE3 transport activity and regulation in vivo. NHERF1, 2 and 3 were differentially distributed to rafts and non-rafts, with NHERF2 being most raft-associated and NHERF3 entirely non-raft associated. NHERF2 expression enhanced the localization of NHE3 to membrane rafts. The use of acid sphingomyelinase-deficient mice, which have altered membrane lipid as well as lipid raft composition, allowed us to test the validity of the lipid raft concept in vivo. The differential association of the NHERFs with the raft-associated and the non-raft fraction of NHE3 in the brush border membrane is one component of the differential and signal-specific NHE3 regulation by the different NHERFs. © 2013 S. Karger AG, Basel.

  1. Ezetimibe Promotes Brush Border Membrane-to-Lumen Cholesterol Efflux in the Small Intestine.

    Directory of Open Access Journals (Sweden)

    Takanari Nakano

    Full Text Available Ezetimibe inhibits Niemann-Pick C1-like 1 (NPC1L1, an apical membrane cholesterol transporter of enterocytes, thereby reduces intestinal cholesterol absorption. This treatment also increases extrahepatic reverse cholesterol transport via an undefined mechanism. To explore this, we employed a trans-intestinal cholesterol efflux (TICE assay, which directly detects circulation-to-intestinal lumen 3H-cholesterol transit in a cannulated jejunal segment, and found an increase of TICE by 45%. To examine whether such increase in efflux occurs at the intestinal brush border membrane(BBM-level, we performed luminal perfusion assays, similar to TICE but the jejunal wall was labelled with orally-given 3H-cholesterol, and determined elevated BBM-to-lumen cholesterol efflux by 3.5-fold with ezetimibe. Such increased efflux probably promotes circulation-to-lumen cholesterol transit eventually; thus increases TICE. Next, we wondered how inhibition of NPC1L1, an influx transporter, resulted in increased efflux. When we traced orally-given 3H-cholesterol in mice, we found that lumen-to-BBM 3H-cholesterol transit was rapid and less sensitive to ezetimibe treatment. Comparison of the efflux and fractional cholesterol absorption revealed an inverse correlation, indicating the efflux as an opposite-regulatory factor for cholesterol absorption efficiency and counteracting to the naturally-occurring rapid cholesterol influx to the BBM. These suggest that the ezetimibe-stimulated increased efflux is crucial in reducing cholesterol absorption. Ezetimibe-induced increase in cholesterol efflux was approximately 2.5-fold greater in mice having endogenous ATP-binding cassette G5/G8 heterodimer, the major sterol efflux transporter of enterocytes, than the knockout counterparts, suggesting that the heterodimer confers additional rapid BBM-to-lumen cholesterol efflux in response to NPC1L1 inhibition. The observed framework for intestinal cholesterol fluxes may provide ways to

  2. Anti-glycosyl antibodies in lipid rafts of the enterocyte brush border: a possible host defense against pathogens

    DEFF Research Database (Denmark)

    Hansen, Gert Helge; Pedersen, Esben D K; Immerdal, Lissi

    2005-01-01

    a major part of the immunoglobulins at the lumenal surface of the gut. The antibodies were associated with lipid rafts at the brush border, and they frequently (52%) coclustered with the raft marker galectin 4. A lactose wash increased the susceptibility of the brush border toward lectin peanut agglutin...

  3. Jejunal brush border microvillous alterations in Giardia muris-infected mice: role of T lymphocytes and interleukin-6.

    Science.gov (United States)

    Scott, K G; Logan, M R; Klammer, G M; Teoh, D A; Buret, A G

    2000-06-01

    Intestinal colonization with the protozoan Giardia causes diffuse brush border microvillous alterations and disaccharidase deficiencies, which in turn are responsible for intestinal malabsorption and maldigestion. The role of T cells and/or cytokines in the pathogenesis of Giardia-induced microvillous injury remains unclear. The aim of this study was to assess the role of T cells and interleukin-6 (IL-6) in the brush border pathophysiology of acute murine giardiasis in vivo. Athymic nude (nu(-)/nu(-)) CD-1 mice and isogenic immunocompetent (nu(+)/nu(+)) CD-1 mice (4 weeks old) received an axenic Giardia muris trophozoite inoculum or vehicle (control) via orogastric gavage. Weight gain and food intake were assessed daily. On day 6, segments of jejunum were assessed for parasite load, brush border ultrastructure, IL-6 content, maltase and sucrase activities, villus-crypt architecture, and intraepithelial lymphocyte (IEL) infiltration. Despite similar parasitic loads on day 6, infected immunocompetent animals, but not infected nude mice, showed a diffuse loss of brush border microvillous surface area, which was correlated with a significant reduction in maltase and sucrase activities and a decrease in jejunal IL-6 concentration. In both athymic control and infected mice, jejunal brush border surface area and disaccharidases were high, but levels of tissue IL-6 were low and comparable to the concentration measured in immunocompetent infected animals. In both immunocompetent and nude mice, infection caused a small but significant increase in the numbers of IELs. These findings suggest that the enterocyte brush border injury and malfunction seen in giardiasis is, at least in part, mediated by thymus-derived T lymphocytes and that suppressed jejunal IL-6 does not necessarily accompany microvillous shortening.

  4. Effects of divalent cations on vitamin B12 adsorption to brush borders of rat intestine

    International Nuclear Information System (INIS)

    Miyata, Satoru; Inada, Masami

    1976-01-01

    A brush border preparation from rat intestine was incubated with rat intrinsic factor-vitamin B 12 complex in 0.01M Tris-HCl buffer, pH 7.4. The 57 Co-B 12 uptake to brush borders was proportional to the amount of protein or to alkaline phosphatase activity in the preparations. The uptake increased with time of incubation. At 37 0 C, the uptake after incubation for 15 min. was 80-85% of that for one hr. The uptake at 4 0 C was approximately 70% of that at 37 0 C. There was no difference as a result of adding glucose to the incubation medium. The uptake was observed in the alkaline environment above pH 6.3. Maximum uptake occurred at pH 8.0. Brush borders washed with Krebs-Ringer bicarbonate buffer (pH 7.4) exhibited no difference in B 12 uptake, whether in the presence of absence of calcium ion. But brush borders washed with ethylenediaminetetraacetate exhibited no uptake when incubated in calcium-free medium. The uptake reached a maximum by addition of calcium ion at a concentration of 0.3 mM, and was not alter up to 10 mM. Addition of magnesium ion exhibited no uptake. Calcium-dependent B 12 uptake was markedly inhibited by manganese ion. Magnesium ion seemed to slightly inhibit the calcium-dependent uptake. (auth.)

  5. Studies on the mechanism of cholesterol uptake and on the effects of bile salts on this uptake by brush-border membranes isolated from rabbit small intestine.

    Science.gov (United States)

    Proulx, P; Aubry, H; Brglez, I; Williamson, D G

    1984-12-19

    The effect of bile salts and other surfactants on the rate of incorporation of cholesterol into isolated brush-border membranes was tested. At constant cholesterol concentration, a stimulatory effect of taurocholate was noticed which increased as the bile salt concentration was raised to 20 mM. Taurodeoxycholate was as effective as taurocholate at concentrations of up to 5 mM and inhibited at higher concentrations. Glycocholate was only moderately stimulatory whereas cholate was nearly as effective as taurocholate at concentrations above 5 mM. Other surfactants such as sodium lauryl sulfate and Triton X-100 were very inhibitory at all concentrations tried whereas cetyltrimethyl ammonium chloride was stimulatory only at a very low range of concentrations. These micellizing agents all caused some disruption of the membranes and the greater effectiveness of taurocholate in stimulating sterol uptake was partly relatable to the weaker membrane solubilizing action of this bile salt. Preincubation of membranes with 20 mM taurocholate followed by washing and exposure to cholesterol-containing lipid suspensions lacking bile salt, did not enhance the incorporation of the sterol. In the absence of bile salt the incorporation of cholesterol was unaffected by stirring of the incubation mixtures. Increasing the cholesterol concentration in the mixed micelle while keeping the concentration of bile salt constant caused an increase in rate of sterol incorporation. This increased rate was seen whether the cholesterol suspension was turbid, i.e., contained non-micellized cholesterol, or whether it was optically-clear and contained only monomers and micelles. When the concentration of taurocholate and cholesterol were increased simultaneously such that the concentration ratio of these two components was kept constant, there resulted a corresponding increase in rate of cholesterol uptake. The initial rates of cholesterol incorporation from suspensions containing micellar and monomer

  6. Relationship of membrane-bound sulfhydryl groups to vitamin D-stimulated uptake of [75Se]Selenite by the brush border membrane vesicles from chick duodenum

    International Nuclear Information System (INIS)

    Mykkanen, H.M.; Wasserman, R.H.

    1990-01-01

    The uptake of selenite by purified brush border membrane vesicles isolated from duodena of rachitic or vitamin D-treated chicks was studied by using radioactive selenite and a rapid filtration technique. Cholecalciferol treatment (500 IU at 72 h) significantly enhanced selenite uptake, a response that decreased when the vesicles were stored at room temperature for 2.5 h prior to the uptake measurement. Preincubation of the vesicles in 1.0 mmol/L H2O2 reduced [75Se]selenite uptake, indicating the involvement of oxidizable groups in the uptake reaction. Iodoacetic acid (IAA), a sulfhydryl-blocking reagent, at 1-2 mmol/L concentration eliminated the difference in selenite uptake due to cholecalciferol and had no effect on vesicles from rachitic animals. A higher concentration of IAA (10 mmol/L) enhanced selenite uptake manyfold and increased the absolute difference due to cholecalciferol treatment. Single intravenous doses of 100 IU cholecalciferol, 100 IU ergocalciferol, or 0.1 micrograms 1,25-dihydroxycholecalciferol also stimulated selenite uptake, suggesting a general response to vitamin D compounds. Normal animals given a single dose of 1,25-dihydroxycholecalciferol 12 h prior to killing also responded. Treatments that enhanced the uptake of [75Se]selenite also increased the amount of membrane-bound sulfhydryl groups, suggesting the involvement of membrane-bound sulfhydryl groups in the vitamin D response. A significant increase in selenite uptake by intravenous 1,25-dihydroxycholecalciferol occurred within 10 min. This rapid effect provides a new tool to probe early biochemical effects of vitamin D on intestinal epithelium

  7. Radiation inactivation studies of renal brush border water and urea transport

    International Nuclear Information System (INIS)

    Verkman, A.S.; Dix, J.A.; Seifter, J.L.; Skorecki, K.L.; Jung, C.Y.; Ausiello, D.A.

    1985-01-01

    Radiation inactivation was used to determine the nature and molecular weight of water and urea transport pathways in brush border membrane vesicles (BBMV) isolated from rabbit renal cortex. BBMV were frozen to -50 degrees C, irradiated with 1.5 MeV electrons, thawed, and assayed for transport or enzyme activity. The freezing process had no effect on enzyme or transport kinetics. BBMV alkaline phosphatase activity gave linear ln(activity) vs. radiation dose plots with a target size of 68 +/- 3 kDa, similar to previously reported values. Water and solute transport were measured using the stopped-flow light-scattering technique. The rates of acetamide and osmotic water transport did not depend on radiation dose (0-7 Mrad), suggesting that transport of these substances does not require a protein carrier. In contrast, urea and thiourea transport gave linear ln(activity) vs. dose curves with a target size of 125-150 kDa; 400 mM urea inhibited thiourea flux by -50% at 0 and 4.7 Mrad, showing that radiation does not affect inhibitor binding to surviving transporters. These studies suggest that BBMV urea transport requires a membrane protein, whereas osmotic water transport does not

  8. Lipid raft organization and function in the small intestinal brush border

    DEFF Research Database (Denmark)

    Danielsen, E M; Hansen, Gert Helge

    2008-01-01

    proteinases, are protected from untimely release into the gut lumen. Finally, anti-glycosyl antibodies, synthesized by plasma cells locally in the gut, are deposited on the brush border glycolipid rafts, protecting the epithelium from lumenal pathogens that exploit lipid rafts as portals for entry...... to the organism....

  9. Induction of a gradual, reversible morphogenesis of its host's epithelial brush border by Vibrio fischeri.

    Science.gov (United States)

    Lamarcq, L H; McFall-Ngai, M J

    1998-02-01

    Bacteria exert a variety of influences on the morphology and physiology of animal cells whether they are pathogens or cooperative partners. The association between the luminous bacterium Vibrio fischeri and the sepiolid squid Euprymna scolopes provides an experimental model for the study of the influence of extracellular bacteria on the development of host epithelia. In this study, we analyzed bacterium-induced changes in the brush borders of the light organ crypt epithelia during the initial hours following colonization of this tissue. Transmission electron microscopy of the brush border morphology in colonized and uncolonized hosts revealed that the bacteria effect a fourfold increase in microvillar density over the first 4 days of the association. Estimates of the proportions of bacterial cells in contact with host microvilli showed that the intimacy of the bacterial cells with animal cell surfaces increases significantly during this time. Antibiotic curing of the organ following colonization showed that sustained interaction with bacteria is essential for the retention of the induced morphological changes. Bacteria that are defective in either light production or colonization efficiency produced changes similar to those by the parent strain. Conventional fluorescence and confocal scanning laser microscopy revealed that the brush border is supported by abundant filamentous actin. However, in situ hybridization with beta-actin probes did not show marked bacterium-induced increases in beta-actin gene expression. These experiments demonstrate that the E. scolopes-V. fischeri system is a viable model for the experimental study of bacterium-induced changes in host brush border morphology.

  10. Binding kinetics of Clostridium difficile toxins A and B to intestinal brush border membranes from infant and adult hamsters

    International Nuclear Information System (INIS)

    Rolfe, R.D.

    1991-01-01

    This study was undertaken to determine if the relative resistance of neonates and infants to Clostridium difficile-associated intestinal disease can be related to age-dependent differences in intestinal receptors for C. difficile toxins A and B. Brush border membranes (BBMs) from the small intestines of adult and infant hamsters were examined for their ability to bind radiolabeled toxins A and B. [125I]toxin A bound to both infant and adult hamster BBMs at physiological temperature, whereas [125I]toxin B did not bind to the BBMs under any of the conditions examined. The number of [125I]toxin A molecules bound at saturation was approximately 4 x 10(10) per micrograms of membrane protein for adult BBMs and 1 x 10(11) per micrograms of membrane protein for infant BBMs. Scatchard plot analysis suggested the presence of a single class of toxin A binding sites on both infant and adult hamster BBMs. Maximal binding capacity and Kd values were 0.63 pmol/mg of protein and 66.7 nM, respectively, for the infant BBMs, and 0.24 pmol/mg of protein and 27 nM, respectively, for the adult BBMs. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic analyses of extracted BBM proteins revealed differences in the proteins of infant and adult BBMs. However, there were not any detectable differences in the protein bands which bound [125I]toxin A between infant and adult hamsters. The results from these investigations indicate that differences in the binding kinetics of toxins A and/or B to infant and adult hamster BBMs do not account for the observed differences in their susceptibility to C. difficile-associated intestinal disease

  11. Binding kinetics of Clostridium difficile toxins A and B to intestinal brush border membranes from infant and adult hamsters

    Energy Technology Data Exchange (ETDEWEB)

    Rolfe, R.D. (Texas Tech Univ. Health Sciences Center, Lubbock (USA))

    1991-04-01

    This study was undertaken to determine if the relative resistance of neonates and infants to Clostridium difficile-associated intestinal disease can be related to age-dependent differences in intestinal receptors for C. difficile toxins A and B. Brush border membranes (BBMs) from the small intestines of adult and infant hamsters were examined for their ability to bind radiolabeled toxins A and B. (125I)toxin A bound to both infant and adult hamster BBMs at physiological temperature, whereas (125I)toxin B did not bind to the BBMs under any of the conditions examined. The number of (125I)toxin A molecules bound at saturation was approximately 4 x 10(10) per micrograms of membrane protein for adult BBMs and 1 x 10(11) per micrograms of membrane protein for infant BBMs. Scatchard plot analysis suggested the presence of a single class of toxin A binding sites on both infant and adult hamster BBMs. Maximal binding capacity and Kd values were 0.63 pmol/mg of protein and 66.7 nM, respectively, for the infant BBMs, and 0.24 pmol/mg of protein and 27 nM, respectively, for the adult BBMs. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic analyses of extracted BBM proteins revealed differences in the proteins of infant and adult BBMs. However, there were not any detectable differences in the protein bands which bound (125I)toxin A between infant and adult hamsters. The results from these investigations indicate that differences in the binding kinetics of toxins A and/or B to infant and adult hamster BBMs do not account for the observed differences in their susceptibility to C. difficile-associated intestinal disease.

  12. Improving Hemocompatibility of Membranes for Extracorporeal Membrane Oxygenators by Grafting Nonthrombogenic Polymer Brushes.

    Science.gov (United States)

    Obstals, Fabian; Vorobii, Mariia; Riedel, Tomáš; de Los Santos Pereira, Andres; Bruns, Michael; Singh, Smriti; Rodriguez-Emmenegger, Cesar

    2018-03-01

    Nonthrombogenic modifications of membranes for extracorporeal membrane oxygenators (ECMOs) are of key interest. The absence of hemocompatibility of these membranes and the need of anticoagulation of patients result in severe and potentially life-threatening complications during ECMO treatment. To address the lack of hemocompatibility of the membrane, surface modifications are developed, which act as barriers to protein adsorption on the membrane and, in this way, prevent activation of the coagulation cascade. The modifications are based on nonionic and zwitterionic polymer brushes grafted directly from poly(4-methyl-1-pentene) (TPX) membranes via single electron transfer-living radical polymerization. Notably, this work introduces the first example of well-controlled surface-initiated radical polymerization of zwitterionic brushes. The antifouling layers markedly increase the recalcification time (a proxy of initiation of coagulation) compared to bare TPX membranes. Furthermore, platelet and leukocyte adhesion is drastically decreased, rendering the ECMO membranes hemocompatible. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Exposure to Engineered Nanomaterial Results in Disruption of Brush Borders in Epithelia Models in vitro

    Science.gov (United States)

    Faust, James J.

    Engineered nanoparticles (NP; 10-9 m) have found use in a variety of consumer goods and medical devices because of the unique changes in material properties that occur when synthesized on the nanoscale. Although many definitions for nanoparticle exist, from the perspective of size, nanoparticle is defined as particles with diameters less than 100 nm in any external dimension. Examples of their use include titanium dioxide added as a pigment in products intended to be ingested by humans, silicon dioxide NPs are used in foods as an anticaking agent, and gold or iron oxide NPs can be used as vectors for drug delivery or contrast agents for specialized medical imaging. Although the intended use of these NPs is often to improve human health, it has come to the attention of investigators that NPs can have unintended or even detrimental effects on the organism. This work describes one such unintended effect of NP exposure from the perspective of exposure via the oral route. First, this Dissertation will explain an event referred to as brush border disruption that occurred after nanoparticles interacted with an in vitro model of the human intestinal epithelium. Second, this Dissertation will identify and characterize several consumer goods that were shown to contain titanium dioxide that are intended to be ingested. Third, this Dissertation shows that sedimentation due to gravity does not artifactually result in disruption of brush borders as a consequence of exposure to food grade titanium dioxide in vitro. Finally, this Dissertation will demonstrate that iron oxide nanoparticles elicited similar effects after exposure to an in vitro brush border expressing model of the human placenta. Together, these data suggest that brush border disruption is not an artifact of the material/cell culture model, but instead represents a bona fide biological response as a result of exposure to nanomaterial.

  14. The PDZ domain of the guanine nucleotide exchange factor PDZGEF directs binding to phosphatidic acid during brush border formation.

    Directory of Open Access Journals (Sweden)

    Sarah V Consonni

    Full Text Available PDZGEF is a guanine nucleotide exchange factor for the small G protein Rap. It was recently found that PDZGEF contributes to establishment of intestinal epithelial polarity downstream of the kinase Lkb1. By binding to phosphatidic acid enriched at the apical membrane, PDZGEF locally activates Rap2a resulting in induction of brush border formation via a pathway that includes the polarity players TNIK, Mst4 and Ezrin. Here we show that the PDZ domain of PDZGEF is essential and sufficient for targeting PDZGEF to the apical membrane of polarized intestinal epithelial cells. Inhibition of PLD and consequently production of phosphatidic acid inhibitis targeting of PDZGEF to the plasma membrane. Furthermore, localization requires specific positively charged residues within the PDZ domain. We conclude that local accumulation of PDZGEF at the apical membrane during establishment of epithelial polarity is mediated by electrostatic interactions between positively charged side chains in the PDZ domain and negatively charged phosphatidic acid.

  15. Experimental type II diabetes and related models of impaired glucose metabolism differentially regulate glucose transporters at the proximal tubule brush border membrane.

    Science.gov (United States)

    Chichger, Havovi; Cleasby, Mark E; Srai, Surjit K; Unwin, Robert J; Debnam, Edward S; Marks, Joanne

    2016-06-01

    What is the central question of this study? Although SGLT2 inhibitors represent a promising treatment for patients suffering from diabetic nephropathy, the influence of metabolic disruption on the expression and function of glucose transporters is largely unknown. What is the main finding and its importance? In vivo models of metabolic disruption (Goto-Kakizaki type II diabetic rat and junk-food diet) demonstrate increased expression of SGLT1, SGLT2 and GLUT2 in the proximal tubule brush border. In the type II diabetic model, this is accompanied by increased SGLT- and GLUT-mediated glucose uptake. A fasted model of metabolic disruption (high-fat diet) demonstrated increased GLUT2 expression only. The differential alterations of glucose transporters in response to varying metabolic stress offer insight into the therapeutic value of inhibitors. SGLT2 inhibitors are now in clinical use to reduce hyperglycaemia in type II diabetes. However, renal glucose reabsorption across the brush border membrane (BBM) is not completely understood in diabetes. Increased consumption of a Western diet is strongly linked to type II diabetes. This study aimed to investigate the adaptations that occur in renal glucose transporters in response to experimental models of diet-induced insulin resistance. The study used Goto-Kakizaki type II diabetic rats and normal rats rendered insulin resistant using junk-food or high-fat diets. Levels of protein kinase C-βI (PKC-βI), GLUT2, SGLT1 and SGLT2 were determined by Western blotting of purified renal BBM. GLUT- and SGLT-mediated d-[(3) H]glucose uptake by BBM vesicles was measured in the presence and absence of the SGLT inhibitor phlorizin. GLUT- and SGLT-mediated glucose transport was elevated in type II diabetic rats, accompanied by increased expression of GLUT2, its upstream regulator PKC-βI and SGLT1 protein. Junk-food and high-fat diet feeding also caused higher membrane expression of GLUT2 and its upstream regulator PKC

  16. Angiotensin 2 directly increases rabbit renal brush-border membrane sodium transport: Presence of local signal transduction system

    International Nuclear Information System (INIS)

    Morduchowicz, G.A.; Sheikh-Hamad, D.; Dwyer, B.E.; Stern, N.; Jo, O.D.; Yanagawa, N.

    1991-01-01

    In the present study, the authors have examined the direct actions of angiotensin II (AII) in rabbit renal brush border membrane (BBM) where binding sites for AII exist. Addition of AII (10(-11)-10(-7) M) was found to stimulate 22Na+ uptake by the isolated BBM vesicles directly. All did not affect the Na(+)-dependent BBM glucose uptake, and the effect of AII on BBM 22Na+ uptake was inhibited by amiloride, suggesting the involvement of Na+/H+ exchange mechanism. BBM proton permeability as assessed by acridine orange quenching was not affected by AII, indicating the direct effect of AII on Na+/H+ antiport system. In search of the signal transduction mechanism, it was found that AII activated BBM phospholipase A2 (PLA) and that BBM contains a 42-kDa guanine nucleotide-binding regulatory protein (G-protein) that underwent pertussis toxin (PTX)-catalyzed ADP-ribosylation. Addition of GTP potentiated, while GDP-beta S or PTX abolished, the effects of AII on BBM PLA and 22Na+ uptake, suggesting the involvement of G-protein in AII's actions. On the other hand, inhibition of PLA by mepacrine prevented AII's effect on BBM 22Na+ uptake, and activation of PLA by mellitin or addition of arachidonic acid similarly enhanced BBM 22Na+ uptake, suggesting the role of PLA activation in mediating AII's effect on BBM 22Na+ uptake. In summary, results of the present study show a direct stimulatory effect of AII on BBM Na+/H+ antiport system, and suggest the presence of a local signal transduction system involving G-protein mediated PLA activation

  17. Distribution of IGF receptors in the plasma membrane of proximal tubular cells

    International Nuclear Information System (INIS)

    Hammerman, M.R.; Rogers, S.

    1987-01-01

    To characterize the distribution of receptors for insulin-like growth factors I and II (IGF I and II) in the plasma membrane of the renal proximal tubular cell, the authors measured binding of 125 I-labeled IGF I and 125 I-labeled IGF II to proximal tubular basolateral and brush-border membranes and characterized IGF I-stimulated phosphorylation of detergent-solubilized membranes. 125 I-IGF bound primarily to a 135,000 relative molecular weight (M r ) protein and IGF II to a 260,000 M r protein in isolated membranes. Binding of 125 I-IGF I was severalfold greater in basolateral than in brush-border membranes. IGF I-stimulated phosphorylation of the 92,000 M r β-subunit of its receptors could be demonstrated only in basolateral membranes. These findings are consistent with an asymmetrical distribution of receptors for IGF I in the plasma membrane of the renal proximal tubular cell, localization being primary on the basolateral side. In contrast, binding of 125 I-IGF II to isolated basolateral and brush-border membranes was equivalent, suggesting that receptors for this peptide are distributed more symmetrically in the plasma membrane. The findings suggest that the action of IGF I in proximal tubule are mediated via interaction of circulating peptide with specific receptors in the basolateral membrane. However, the findings established the potential for actions of IGF II to be exerted in proximal tubule via interaction with both basolateral and/or brush-border membrane receptors

  18. Multilayer affinity adsorption of albumin on polymer brushes modified membranes in a continuous-flow system.

    Science.gov (United States)

    Hu, Meng-Xin; Li, Xiang; Li, Ji-Nian; Huang, Jing-Jing; Ren, Ge-Rui

    2018-02-23

    Polymer brushes modified surfaces have been widely used for protein immobilization and isolation. Modification of membranes with polymer brushes increases the surface concentration of affinity ligands used for protein binding. Albumin is one of the transporting proteins and shows a high affinity to bile acids. In this work, the modified membranes with cholic acid-containing polymer brushes can be facilely prepared by the immobilization of cholic acid on the poly(2-hydroxyethyl methacrylate) grafted microporous polypropylene membranes (MPPMs) for affinity adsorption of albumin. ATR/FT-IR and X-ray photoelectron spectroscopy were used to characterize the chemical composition of the modified membranes. Water contact angle measurements were used to analyze the hydrophilic/hydrophobic properties of the membrane surface. The modified MPPMs show a high affinity to albumin and have little non-specific adsorption of hemoglobin. The dynamic binding capacity of albumin in the continous-flow system increases with the cycle number and feed rate as the binding degree of cholic acid is moderate. The highest binding capacity of affinity membranes is about 52.49 g/m 2 membrane, which is about 24 times more than the monolayer binding capacity. These results reveal proteins could be captured in multilayers by the polymer brushes containing affinity ligands similar to the polymer brushes containing ion-exchange groups, which open up the potential of the polymer brushes containing affinity ligands in protein or another components separation. And the cholic acid containing polymer brushes modified membranes has the promising potential for albumin separation and purification rapidly from serum or fermented solution in medical diagnosis and bioseparation. Copyright © 2018 Elsevier B.V. All rights reserved.

  19. Interactions of [14C]phosphonoformic acid with renal cortical brush-border membranes. Relationship to the Na+-phosphate co-transporter

    International Nuclear Information System (INIS)

    Szczepanska-Konkel, M.; Yusufi, A.N.; Dousa, T.P.

    1987-01-01

    Since phosphonoformic acid (PFA) acts as a specific competitive inhibitor of Na+-Pi co-transport across renal brush-border membrane (BBM), we employed the [ 14 C]PFA as a probe to determine the mechanism of its interaction with rat renal BBM. The binding of [ 14 C]PFA to BBM vesicles (BBMV), with Na+ present in extravesicular medium (Na+o), was time- and temperature-dependent. The replacement of Na+o with other monovalent cations reduced the PFA binding by -80%. Cl- was the most effective accompanying monovalent anion as NaCl for maximum PFA binding. The Na+o increased the apparent affinity of BBMV for [ 14 C]PFA binding, but it did not change the maximum binding capacity. The maximum [ 14 C]PFA binding was achieved at Na+o approximately equal to 50 mM. The extent of Na+-dependent [ 14 C]PFA binding correlated with percent inhibition by an equimolar dose of PFA of the dependent BBMV uptake of 32Pi. Intravesicular Na+ (Na+i) decreased [ 14 C]PFA binding, on BBMV, and this inhibition by Na+i was dependent on the presence of Na+o. The increase in Na+i, at constant [Na+]o, decreased the Vmax, but not the Km, for [ 14 C]PFA binding on BBMV. Bound [ 14 C]PFA was displaced from BBMV by phosphonocarboxylic acids proportionally to their ability to inhibit gradient-dependent Pi transport, whereas other monophosphonates, diphosphonates, L-proline, or D-glucose did not influence the [ 14 C]PFA binding. The Na+-dependent binding of [ 14 C]PFA and of [ 3 H]phlorizin by BBMV was 10 times higher than binding of these ligands to renal basolateral membranes and to mitochondria. [ 14 C]PFA probably binds onto the same locus on the luminal surface of BBM, where Pi and Na+ form a ternary complex with the Na+-Pi co-transporter

  20. Angiotensin 2 directly increases rabbit renal brush-border membrane sodium transport: Presence of local signal transduction system

    Energy Technology Data Exchange (ETDEWEB)

    Morduchowicz, G.A.; Sheikh-Hamad, D.; Dwyer, B.E.; Stern, N.; Jo, O.D.; Yanagawa, N. (Sepulveda Veterans Administration, CA (USA))

    1991-05-01

    In the present study, the authors have examined the direct actions of angiotensin II (AII) in rabbit renal brush border membrane (BBM) where binding sites for AII exist. Addition of AII (10(-11)-10(-7) M) was found to stimulate 22Na+ uptake by the isolated BBM vesicles directly. All did not affect the Na(+)-dependent BBM glucose uptake, and the effect of AII on BBM 22Na+ uptake was inhibited by amiloride, suggesting the involvement of Na+/H+ exchange mechanism. BBM proton permeability as assessed by acridine orange quenching was not affected by AII, indicating the direct effect of AII on Na+/H+ antiport system. In search of the signal transduction mechanism, it was found that AII activated BBM phospholipase A2 (PLA) and that BBM contains a 42-kDa guanine nucleotide-binding regulatory protein (G-protein) that underwent pertussis toxin (PTX)-catalyzed ADP-ribosylation. Addition of GTP potentiated, while GDP-beta S or PTX abolished, the effects of AII on BBM PLA and 22Na+ uptake, suggesting the involvement of G-protein in AII's actions. On the other hand, inhibition of PLA by mepacrine prevented AII's effect on BBM 22Na+ uptake, and activation of PLA by mellitin or addition of arachidonic acid similarly enhanced BBM 22Na+ uptake, suggesting the role of PLA activation in mediating AII's effect on BBM 22Na+ uptake. In summary, results of the present study show a direct stimulatory effect of AII on BBM Na+/H+ antiport system, and suggest the presence of a local signal transduction system involving G-protein mediated PLA activation.

  1. Brush border membrane vesicle and Caco-2 cell line: Two experimental models for evaluation of absorption enhancing effects of saponins, bile salts, and some synthetic surfactants

    Directory of Open Access Journals (Sweden)

    Eskandar Moghimipour

    2016-01-01

    Full Text Available The aim of this study was to investigate the influence of absorption enhancers in the uptake of hydrophilic compounds. The permeation of the two hydrophilic drug models gentamicin and 5 (6-carboxyfluorescein (CF across the brush border membrane vesicles and Caco-2 cell lines were evaluated using total saponins of Acanthophyllum squarrosum, Quillaja saponaria, sodium lauryl sulfate, sodium glycocholate, sodium taurodeoxycholate , and Tween 20 as absorption enhancers. Transepithelial electrical resistance (TEER measurement was utilized to assess the paracellular permeability of cell lines. Confocal laser scanning microscopy (CLSM was performed to obtain images of the distribution of CF in Caco-2 cells. These compounds were able to loosen tight junctions, thus increasing paracellular permeability. CLSM confirmed the effect of these absorption enhancers on CF transport across Caco-2 lines and increased the Caco-2 permeability via transcellular route. It was also confirmed that the decrease in TEER was transient and reversible after removal of permeation enhancers.

  2. Apolipoprotein A-1 (apoA-1) deposition in, and release from, the enterocyte brush border: a possible role in transintestinal cholesterol efflux (TICE)?

    Science.gov (United States)

    Danielsen, E Michael; Hansen, Gert H; Rasmussen, Karina; Niels-Christiansen, Lise-Lotte; Frenzel, Franz

    2012-03-01

    Transintestinal cholesterol efflux (TICE) has been proposed to represent a non-hepatobiliary route of cholesterol secretion directly "from blood to gut" and to play a physiologically significant role in excretion of neutral sterols, but so far little is known about the proteins involved in the process. We have previously observed that apolipoprotein A-1 (apoA-1) synthesized by enterocytes of the small intestine is mainly secreted apically into the gut lumen during fasting where its assembly into chylomicrons and basolateral discharge is at a minimal level. In the present work we showed, both by immunomicroscopy and subcellular fractionation, that a fraction of the apically secreted apoA-1 in porcine small intestine was not released from the cell surface but instead deposited in the brush border. Cholesterol was detected in immunoisolated microvillar apoA-1, and it was partially associated with detergent resistant membranes (DRMs), indicative of localization in lipid raft microdomains. The apolipoprotein was not readily released from microvillar vesicles by high salt or by incubation with phosphatidylcholine-specific phospholipase C or trypsin, indicating a relatively firm attachment to the membrane bilayer. However, whole bile or taurocholate efficiently released apoA-1 at low concentrations that did not solubilize the transmembrane microvillar protein aminopeptidase N. Based on these findings and the well known role played by apoA-1 in extrahepatic cellular cholesterol removal and reverse cholesterol transport (RCT), we propose that brush border-deposited apoA-1 in the small intestine acts in TICE by mediating cholesterol efflux into the gut lumen. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. Small molecule pinocytosis and clathrin-dependent endocytosis at the intestinal brush border

    DEFF Research Database (Denmark)

    Danielsen, Erik Michael; Hansen, Gert H

    2016-01-01

    Pinocytosis at the small intestinal brush border was studied in postweaned porcine cultured mucosal explants, using the fluorescent polar probes Alexa hydrazide (AH, MW 570), Texas red dextran (TRD, MW ~ 3000), and Cascade blue dextran (CBD, MW ~ 10,000). Within 1 h, AH appeared in a string...... of subapical punctae in enterocytes, indicative of an ongoing constitutive pinocytosis. By comparison, TRD was taken up less efficiently into the same compartment, and no intracellular labeling of CBD was detectable, indicating that only small molecules are pinocytosed from the postweaned gut lumen. AH...

  4. Comparative Proteomic Analysis of the Effect of Periplocoside P from Periploca sepium on Brush Border Membrane Vesicles in Midgut Epithelium of Mythimna separata Larvae

    Directory of Open Access Journals (Sweden)

    Mingxing Feng

    2017-12-01

    Full Text Available Periplocoside P (PSP, a novel compound isolated from Periploca sepium Bunge, possesses insecticidal activity against some lepidopterans, such as Mythimna separata. In M. separata, the brush border membrane vesicles of the midgut epithelium are the initial site of action of periplocosides. We conducted two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization time of flight/time of flight mass spectrometry analysis to analyze differentially expressed proteins (DEPs from periplocoside P (PSP-treated M. separata. We successfully isolated seven up-regulated and three down-regulated DEPs that have been previously identified, as well as a novel DEP. The DEPs are implicated in protein degradation, transporter, folding, and synthesis, and in juvenile hormone biosynthesis. DEPs involved in the oxidative phosphorylation energy metabolism pathway are enriched. Through real-time polymerase chain reaction assay, we confirmed that vma1 expression is significantly up-regulated expression levels in PSP-treated M. separata larvae. Enzymology validation further indicated that PSP can significantly inhibit V-type ATPase activity in a concentration-dependent manner. Given these results, we speculate that in M. separata, the V-type ATPase A subunit in the midgut epithelium is the putative target binding site of periplocosides. This finding provides preliminary evidence for the mode of action of periplocosides.

  5. Improving protein resistance of {alpha}-Al{sub 2}O{sub 3} membranes by modification with POEGMA brushes

    Energy Technology Data Exchange (ETDEWEB)

    He Huating [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing University of Technology, Nanjing 210009 (China); Jing Wenheng, E-mail: jingwenheng@yahoo.com.cn [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing University of Technology, Nanjing 210009 (China); Xing Weihong; Fan Yiqun [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing University of Technology, Nanjing 210009 (China)

    2011-11-15

    A kind of protein-resistant ceramic membrane is prepared by grafting poly(oligo (ethylene glycol) methyl ether methacrylate) (POEGMA) brushes onto the surfaces and pore walls of {alpha}-Al{sub 2}O{sub 3} membrane (AM) by surface-initiated atom-transfer radical polymerization (SI-ATRP). Contact-angle, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and field-emission scanning electron microscopy (FESEM) were measured to confirm that the surfaces and pore walls of the ceramic porous membranes have been modified by the brushes with this method successfully. The protein interaction behavior with the POEGMA modified membranes (AM-POEGMA) was studied by the model protein of bovine serum albumin (BSA). A protein-resistant mechanism of AM-POEGMA was proposed to describe an interesting phenomenon discovered in the filtration experiment, in which the initial flux filtrating BSA solution is higher than the pure water flux. The fouling of AM-POEGMA was easier to remove than AM for the action of POEGMA brushes, indicated that the ceramic porous membranes modified with POEGMA brushes exhibit excellent protein resistance.

  6. Role of intestinal brush border peptidases in the simulated digestion of milk proteins.

    Science.gov (United States)

    Picariello, Gianluca; Miralles, Beatriz; Mamone, Gianfranco; Sánchez-Rivera, Laura; Recio, Isidra; Addeo, Francesco; Ferranti, Pasquale

    2015-05-01

    This study aimed to assess the impact of the "often neglected" intestinal brush border membranes (BBMs) hydrolases on dietary peptides, exploring the possibility that the disintegration of proteins progressed in the small intestine up to a "core" of intrinsically stable oligopeptides, persisting independently on the up-stream breakdown. Samples of sodium caseinate, skim milk powder, and whey protein isolate were submitted to in vitro simulated gastropancreatic digestion using two different procedures: (i) a simplified model involving the main compartmental specific proteases; (ii) a static digestion method based on a frameset of parameters inferred from in vivo. The gastroduodenal digesta were further hydrolyzed with peptidases from porcine jejunal BBM. The peptidomes arising from the two digestion models, characterized by combined HPLC and MS techniques, differed to some extent. However, only specific protein domains survived digestion, among which are potential bioactive or immunogenic (food allergy) peptides. The degree of hydrolysis (DH) after BBM digestion (70-77%) practically did not differ between the digestion models and significantly increased the DH after duodenal steps. Any in vitro digestion model should be supplemented with a jejunal phase to realistically determine the bioaccessibility and bioavailability of dietary peptides. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Correction of enhanced Na(+)-H+ exchange of rat small intestinal brush-border membranes in streptozotocin-induced diabetes by insulin or 1,25-dihydroxycholecalciferol

    International Nuclear Information System (INIS)

    Dudeja, P.K.; Wali, R.K.; Klitzke, A.; Sitrin, M.D.; Brasitus, T.A.

    1991-01-01

    Diabetes was induced in rats by administration of a single i.p. injection of streptozotocin (50 mg/kg body wt). After 7 d, diabetic rats were further treated with insulin or 1,25-dihydroxycholecalciferol [1,25(OH)2D3] for an additional 5-7 d. Control, diabetic, diabetic + insulin, and diabetic + 1,25(OH)2D3 rats were then killed, their proximal small intestines were removed, and villus-tip epithelial cells were isolated and used to prepare brush-border membrane vesicles. Preparations from each of these groups were then analyzed and compared with respect to their amiloride-sensitive, electroneutral Na(+)-H+ exchange activity, using 22 Na uptake as well as acridine orange techniques. The results of these experiments demonstrated that (a) H+ gradient-dependent 22 Na uptake as well as Na+ gradient-dependent transmembrane H+ fluxes were significantly increased in diabetic vesicles compared to their control counterparts, (b) kinetic studies demonstrated that this enhanced 22 Na uptake in diabetes was a result of increased maximal velocity (Vmax) of this exchanger with no change in apparent affinity (Km) for Na+, (c) serum levels of 1,25(OH)2D3 were significantly lower in diabetic animals compared with their control counterparts; and (d) insulin or 1,25(OH)2D3 treatment restored the Vmax alterations to control values, without any significant changes in Km, concomitant with significantly increasing the serum levels of 1,25(OH)2D3 in diabetic animals. These results indicate that Na(+)-H+ activity is significantly increased in proximal small intestinal luminal membranes of streptozotocin-induced diabetic rats. Moreover, alterations in the serum levels of 1,25(OH)2D3 may, at least in part, explain this enhanced antiporter activity and its correction by insulin

  8. Cholesterol depletion of enterocytes. Effect on the Golgi complex and apical membrane trafficking

    DEFF Research Database (Denmark)

    Hansen, Gert Helge; Niels-Christiansen, L L; Thorsen, Evy

    2000-01-01

    Intestinal brush border enzymes, including aminopeptidase N and sucrase-isomaltase, are associated with "rafts" (membrane microdomains rich in cholesterol and sphingoglycolipids). To assess the functional role of rafts in the present work, we studied the effect of cholesterol depletion on apical......, the rates of the Golgi-associated complex glycosylation and association with rafts of newly synthesized aminopeptidase N were reduced, and less of the enzyme had reached the brush border membrane after 2 h of labeling. In contrast, the basolateral Na(+)/K(+)-ATPase was neither missorted nor raft......-associated. Our results implicate the Golgi complex/trans-Golgi network in raft formation and suggest a close relationship between this event and apical membrane trafficking....

  9. Control of biofouling on reverse osmosis polyamide membranes modified with biocidal nanoparticles and antifouling polymer brushes

    KAUST Repository

    Rahaman, Md. Saifur

    2014-01-01

    Thin-film composite (TFC) polyamide reverse osmosis (RO) membranes are prone to biofouling due to their inherent physicochemical surface properties. In order to address the biofouling problem, we have developed novel surface coatings functionalized with biocidal silver nanoparticles (AgNPs) and antifouling polymer brushes via polyelectrolyte layer-by-layer (LBL) self-assembly. The novel surface coating was prepared with polyelectrolyte LBL films containing poly(acrylic acid) (PAA) and poly(ethylene imine) (PEI), with the latter being either pure PEI or silver nanoparticles coated with PEI (Ag-PEI). The coatings were further functionalized by grafting of polymer brushes, using either hydrophilic poly(sulfobetaine) or low surface energy poly(dimethylsiloxane) (PDMS). The presence of both LBL films and sulfobetaine polymer brushes at the interface significantly increased the hydrophilicity of the membrane surface, while PDMS brushes lowered the membrane surface energy. Overall, all surface modifications resulted in significant reduction of irreversible bacterial cell adhesion. In microbial adhesion tests with E. coli bacteria, a normalized cell adhesion in the range of only 4 to 16% on the modified membrane surfaces was observed. Modified surfaces containing silver nanoparticles also exhibited strong antimicrobial activity. Membranes coated with LBL films of PAA/Ag-PEI achieved over 95% inactivation of bacteria attached to the surface within 1 hour of contact time. Both the antifouling and antimicrobial results suggest the potential of using these novel surface coatings in controlling the fouling of RO membranes. © The Royal Society of Chemistry 2014.

  10. The cell adhesion molecule Fasciclin2 regulates brush border length and organization in Drosophila renal tubules

    DEFF Research Database (Denmark)

    Halberg, Kenneth Agerlin; Rainey, Stephanie M.; Veland, Iben Rønn

    2016-01-01

    Multicellular organisms rely on cell adhesion molecules to coordinate cell-cell interactions, and to provide navigational cues during tissue formation. In Drosophila, Fasciclin 2 (Fas2) has been intensively studied due to its role in nervous system development and maintenance; yet, Fas2 is most...... role for this well-known cell adhesion molecule, and propose that Fas2-mediated intermicrovillar homophilic adhesion complexes help stabilize the brush border....

  11. Scavenger receptor class B type I (SR-BI) in pig enterocytes: trafficking from the brush border to lipid droplets during fat absorption

    DEFF Research Database (Denmark)

    Hansen, Gert Helge; Niels-Christiansen, Lise-Lotte W; Immerdal, Lissi

    2003-01-01

    BACKGROUND: Scavenger receptor class B type I (SR-BI) is known to mediate cellular uptake of cholesterol from high density lipoprotein particles and is particularly abundant in liver and steroidogenic tissues. In addition, SR-BI expression in the enterocyte brush border has also been reported...... but its role in the small intestine remains unclear. AIM AND METHODS: To gain insight into the possible function of pig SR-BI during uptake of dietary fat, its localisation in enterocytes was studied in the fasting state and during fat absorption by immunogold electron microscopy and subcellular...... fat, SR-BI is endocytosed from the enterocyte brush border and accumulates in cytoplasmic lipid droplets. Internalisation of the receptor occurs mainly by clathrin coated pits rather than by a caveolae/lipid raft based mechanism....

  12. Inhibition of Na+-P/sub i/ cotransporter in small gut brush border by phosphonocarboxylic acids

    International Nuclear Information System (INIS)

    Loghman-Adham, M.; Szczepsanska-Konkel, M.; Yusufi, A.N.K.; Van Scoy, M.; Dousa, T.P.

    1987-01-01

    The authors examined the effect of phosphonoformic acid (PFA) and phosphonoacetic acid (PAA) upon Na + -P/sub i/ cotransport in brush-border membrane (BBM) from small gut of rat. Both PFA and PAA inhibited the Na + gradient-dependent uptake of 32 P/sub i/ by BBM vesicles (BBMV) prepared from intestinal mucosa but had no effect on Na + -dependent uptakes of D-[ 3 H]glucose, L-[ 3 H]proline, or [ 14 C]succinate. The uptake in the absence of Na + gradient, or uptake at equilibrium period (180 min), was not affected by PFA or by PAA. A chemical analogue of PFA and PAA, phosphonopropionic acid, had only a minor inhibitory effect and phenylphosphonic acid was inactive. Neither PFA nor PAA influenced the activity of rat intestinal BBM alkaline phosphatase. The BBMV from rat jejunum had a much higher capacity for Na + gradient-dependent uptake of 32 P/sub i/ than BBMV from duodenum or ileum. The inhibition of BBMV 32 P/sub i/ transport across rat jejunum by PFA is competitive. They suggest that PFA and PAA are specific inhibitors of Na + gradient-dependent uptake of P/sub i/ by BBMV from small intestinal mucosa and that they could serve as useful experimental tools for the studies of intestinal Na + -P/sub i/ cotransport

  13. Fabrication of cell outer membrane mimetic polymer brush on polysulfone surface via RAFT technique

    International Nuclear Information System (INIS)

    Ma Qian; Zhang Hui; Zhao Jiang; Gong Yongkuan

    2012-01-01

    Highlights: ► Cell membrane mimetic antifouling polymer brush was grown on polysulfone surface. ► Graft density and polymerization degree were calculated from XPS results. ► Water contact angle measurements showed an extremely hydrophilic surface. ► Platelet adhesion and protein adsorption results suggested excellent antifouling ability. - Abstract: Cell membrane mimetic antifouling polymer brush was grown on polysulfone (PSF) membrane by surface-induced reversible addition–fragmentation chain transfer (RAFT) polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC). The RAFT agent immobilized PSF substrate was prepared by successive chloromethylation, amination with ethylenediamine (EDA) and amidation of the amine group of grafted EDA with the carboxylic group of 4-cyanopentanoic acid dithiobenzoate (CPAD). The surface RAFT polymerization of MPC was initiated in aqueous solution by 4,4′-azobis-4-cyanopentanoic acid (ACPA). The formation of PMPC brush coating is evidenced by X-ray photoelectron spectroscopy and water contact angle measurements. The degree of polymerization of PMPC and the polymer grafting density were calculated from the high resolution XPS spectra. The platelet adhesion and protein adsorption results showed that the PMPC-grafted PSF surface has excellent antifouling ability to resist platelet adhesion completely and suppress protein adsorption significantly. This biomimetic and bio-friendly surface RAFT polymerization strategy could be promising for a variety of biomedical applications.

  14. Folding of intestinal brush border enzymes. Evidence that high-mannose glycosylation is an essential early event

    DEFF Research Database (Denmark)

    Danielsen, E M

    1992-01-01

    a posttranslational process. In the presence of fructose, not only the malglycosylated forms but also the electrophoretically normal, high-mannose-glycosylated form of the brush border enzymes were retained in the endoplasmic reticulum and proteolytically degraded. The results obtained demonstrate an intimate...... enzymes. In pulse-labeled mucosal explants, complete synthesis of the polypeptide chains of aminopeptidase N and sucrase-isomaltase required about 2 and 4 min, respectively, whereas maximal antiserum precipitation was acquired with half-times of 4-5 and 8 min, respectively. Fructose, which induces...

  15. Oral administration of thymoquinone mitigates the effect of cisplatin on brush border membrane enzymes, energy metabolism and antioxidant system in rat intestine.

    Science.gov (United States)

    Shahid, Faaiza; Farooqui, Zeba; Abidi, Subuhi; Parwez, Iqbal; Khan, Farah

    2017-10-01

    Cisplatin (CP) is a widely used chemotherapeutic agent that elicits severe gastrointestinal toxicity. Nigella sativa, a member of family Ranunculaceae, is one of the most revered medicinal plant known for its numerous health benefits. Thymoquinone (TQ), a major bioactive component derived from the volatile oil of Nigella sativa seeds, has been shown to improve gastrointestinal functions in animal models of acute gastric/intestinal injury. In view of this, the aim of the present study was to investigate the protective effect of TQ on CP induced toxicity in rat intestine and to elucidate the mechanism underlying these effects. Rats were divided into four groups viz. control, CP, TQ and CP+TQ. Animals in CP+TQ and TQ groups were orally administered TQ (1.5mg/kg bwt) with and without a single intraperitoneal dose of CP (6mg/kg bwt) respectively. The effect of TQ was determined on CP induced alterations in the activities of brush border membrane (BBM), carbohydrate metabolism, and antioxidant defense enzymes in rat intestine. TQ administration significantly mitigated CP induced decline in the specific activities of BBM marker enzymes, both in the mucosal homogenates and in the BBM vesicles (BBMV) prepared from intestinal mucosa. Furthermore, TQ administration restored the redox and metabolic status of intestinal mucosal tissue in CP treated rats. The biochemical results were supported by histopathological findings that showed extensive damage to intestine in CP treated rats and markedly preserved intestinal histoarchitecture in CP and TQ co-treated group. The biochemical and histological data suggest a protective effect of TQ against CP-induced gastrointestinal damage. Thus, TQ may have a potential for clinical application to counteract the accompanying gastrointestinal toxicity in CP chemotherapy. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  16. Intestinal surfactant permeation enhancers and their interaction with enterocyte cell membranes in a mucosal explant system

    DEFF Research Database (Denmark)

    Danielsen, E Michael; Hansen, Gert H

    2017-01-01

    Intestinal permeation enhancers (PEs) are agents aimed to improve oral delivery of therapeutic drugs with poor bioavailability. The main permeability barrier for oral delivery is the intestinal epithelium, and PEs act to increase the paracellular and/or transcellular passage of drugs. Transcellular...... for the fluorescent polar tracer lucifer yellow, but surprisingly, they all also blocked both constitutive -and receptor-mediated pathways of endocytosis from the brush border, indicating a complete arrest of apical membrane trafficking. At the ultrastructural level, the PEs caused longitudinal fusion of brush border...

  17. Apolipoprotein A-1 (apoA-1) deposition in, and release from, the enterocyte brush border

    DEFF Research Database (Denmark)

    Danielsen, E Michael; Hansen, Gert H; Rasmussen, Karina

    2012-01-01

    Transintestinal cholesterol efflux (TICE) has been proposed to represent a non-hepatobiliary route of cholesterol secretion directly "from blood to gut" and to play a physiologically significant role in excretion of neutral sterols, but so far little is known about the proteins involved in the pr......Transintestinal cholesterol efflux (TICE) has been proposed to represent a non-hepatobiliary route of cholesterol secretion directly "from blood to gut" and to play a physiologically significant role in excretion of neutral sterols, but so far little is known about the proteins involved...... transport (RCT), we propose that brush border-deposited apoA-1 in the small intestine acts in TICE by mediating cholesterol efflux into the gut lumen....

  18. Modifications in the brush border enzymes of the small intestine after irradiation at different times of the day

    Energy Technology Data Exchange (ETDEWEB)

    Becciolini, A; Lanini, A; Giache, V; Balzi, M; Bini, R [Florence Univ. (Italy). Ist. di Radiologia

    1982-01-01

    The behaviour of the brush border enzyme activity of the intestinal epithelium after the same sublethal radiation dose to the abdomen at different times of the day was investigated. Three previously observed post-irradiation phases (initial increase of activity, reduction, and return to control values) were confirmed, although with some differences. A later return to normal of lactase was also confirmed. The same dose produced different behaviour of the enzyme activities both during the initial and the recovery phase, depending on the time of the day when irradiation was performed, i.e. on the functional condition of the epithelial cells.

  19. Fouling-resistant polymer brush coatings

    KAUST Repository

    Thérien-Aubin, Héloïse

    2011-11-01

    A major problem to be addressed with thin composite films used in processes such as coatings or water purification is the biofouling of the surface. To address this problem in a model system, functionalized polyaramide membranes containing an atom transfer radical polymerization (ATRP) initiator were synthesized as a versatile approach to easily modify the surface properties of the polyaramide. Poly(methacrylic acid) brushes were grown using surface initiated ATRP followed by the functionalization of the poly(methacrylic acid) brushes with different side-chains chosen to reduce adhesion between the membrane and foulant. The relation between membrane fouling and the physicochemical properties of the surface was investigated in detail. © 2011 Elsevier Ltd. All rights reserved.

  20. Fouling-resistant polymer brush coatings

    KAUST Repository

    Thé rien-Aubin, Hé loï se; Chen, Lin; Ober, Christopher K.

    2011-01-01

    A major problem to be addressed with thin composite films used in processes such as coatings or water purification is the biofouling of the surface. To address this problem in a model system, functionalized polyaramide membranes containing an atom transfer radical polymerization (ATRP) initiator were synthesized as a versatile approach to easily modify the surface properties of the polyaramide. Poly(methacrylic acid) brushes were grown using surface initiated ATRP followed by the functionalization of the poly(methacrylic acid) brushes with different side-chains chosen to reduce adhesion between the membrane and foulant. The relation between membrane fouling and the physicochemical properties of the surface was investigated in detail. © 2011 Elsevier Ltd. All rights reserved.

  1. Myosin-1A Targets to Microvilli Using Multiple Membrane Binding Motifs in the Tail Homology 1 (TH1) Domain*

    Science.gov (United States)

    Mazerik, Jessica N.; Tyska, Matthew J.

    2012-01-01

    One of the most abundant components of the enterocyte brush border is the actin-based monomeric motor, myosin-1a (Myo1a). Within brush border microvilli, Myo1a carries out a number of critical functions at the interface between membrane and actin cytoskeleton. Proper physiological function of Myo1a depends on its ability to bind to microvillar membrane, an interaction mediated by a C-terminal tail homology 1 (TH1) domain. However, little is known about the mechanistic details of the Myo1a-TH1/membrane interaction. Structure-function analysis of Myo1a-TH1 targeting in epithelial cells revealed that an N-terminal motif conserved among class I myosins and a C-terminal motif unique to Myo1a-TH1 are both required for steady state microvillar enrichment. Purified Myo1a bound to liposomes composed of phosphatidylserine and phosphoinositol 4,5-bisphosphate, with moderate affinity in a charge-dependent manner. Additionally, peptides of the N- and C-terminal regions required for targeting were able to compete with Myo1a for binding to highly charged liposomes in vitro. Single molecule total internal reflection fluorescence microscopy showed that these motifs are also necessary for slowing the membrane detachment rate in cells. Finally, Myo1a-TH1 co-localized with both lactadherin-C2 (a phosphatidylserine-binding protein) and PLCδ1-PH (a phosphoinositol 4,5-bisphosphate-binding protein) in microvilli, but only lactaderin-C2 expression reduced brush border targeting of Myo1a-TH1. Together, our results suggest that Myo1a targeting to microvilli is driven by membrane binding potential that is distributed throughout TH1 rather than localized to a single motif. These data highlight the diversity of mechanisms that enable different class I myosins to target membranes in distinct biological contexts. PMID:22367206

  2. Borders as membranes :metaphors and models for improved policy in border regions.

    Energy Technology Data Exchange (ETDEWEB)

    Malczynski, Leonard A.; Passell, Howard David; Forster, Craig B. (University of Utah, Salt Lake City, UT); Cockerill, Kristan (Cockerill Consulting, Boone, NC)

    2005-10-01

    Political borders are controversial and contested spaces. In an attempt to better understand movement along and through political borders, this project applied the metaphor of a membrane to look at how people, ideas, and things ''move'' through a border. More specifically, the research team employed this metaphor in a system dynamics framework to construct a computer model to assess legal and illegal migration on the US-Mexico border. Employing a metaphor can be helpful, as it was in this project, to gain different perspectives on a complex system. In addition to the metaphor, the multidisciplinary team utilized an array of methods to gather data including traditional literature searches, an experts workshop, a focus group, interviews, and culling expertise from the individuals on the research team. Results from the qualitative efforts revealed strong social as well as economic drivers that motivate individuals to cross the border legally. Based on the information gathered, the team concluded that legal migration dynamics were of a scope we did not want to consider hence, available demographic models sufficiently capture migration at the local level. Results from both the quantitative and qualitative data searches were used to modify a 1977 border model to demonstrate the dynamic nature of illegal migration. Model runs reveal that current US-policies based on neo-classic economic theory have proven ineffective in curbing illegal migration, and that proposed enforcement policies are also likely to be ineffective. We suggest, based on model results, that improvement in economic conditions within Mexico may have the biggest impact on illegal migration to the U.S. The modeling also supports the views expressed in the current literature suggesting that demographic and economic changes within Mexico are likely to slow illegal migration by 2060 with no special interventions made by either government.

  3. Effect of nonpathogenic Escherichia coli monoassociation on small intestinal brush-border glycoconjugate moieties and cytokine production after colonization in ex-germ-free rats and pigs

    Czech Academy of Sciences Publication Activity Database

    Kolínská, Jiřina; Zákostelecká, Marie; Schwarzer, Martin; Štěpánková, Renata; Hudcovic, Tomáš; Kozáková, Hana

    2010-01-01

    Roč. 2, - (2010), s. 73-84 ISSN 1179-139X R&D Projects: GA MŠk(CZ) ME10017 Grant - others:GA AV ČR(CZ) IAA500200710; GA ČR(CZ) GA303/09/0449 Program:IA; GA Institutional research plan: CEZ:AV0Z50110509; CEZ:AV0Z50200510 Keywords : nonpathogenic E. coli * glycoconjugates * brush-border vesicles Subject RIV: CE - Biochemistry

  4. Lipid rafts in epithelial brush borders: atypical membrane microdomains with specialized functions

    DEFF Research Database (Denmark)

    Danielsen, E Michael; Hansen, Gert H

    2003-01-01

    of the apical surface sterically accessible for membrane fusion/budding events. Many of these invaginations appear as pleiomorphic, deep apical tubules that extend up to 0.5-1 microm into the underlying terminal web region. Their sensitivity to methyl-beta-cyclodextrin suggests them to contain cholesterol...

  5. Cholera toxin entry into pig enterocytes occurs via a lipid raft- and clathrin-dependent mechanism

    DEFF Research Database (Denmark)

    Hansen, Gert H; Dalskov, Stine-Mathilde; Rasmussen, Christina Rehné

    2005-01-01

    The small intestinal brush border is composed of lipid raft microdomains, but little is known about their role in the mechanism whereby cholera toxin gains entry into the enterocyte. The present work characterized the binding of cholera toxin B subunit (CTB) to the brush border and its internaliz......The small intestinal brush border is composed of lipid raft microdomains, but little is known about their role in the mechanism whereby cholera toxin gains entry into the enterocyte. The present work characterized the binding of cholera toxin B subunit (CTB) to the brush border and its...... accompanied the toxin internalization whereas no formation of caveolae was observed. CTB was strongly associated with the buoyant, detergent-insoluble fraction of microvillar membranes. Neither CTB's raft association nor uptake via clathrin-coated pits was affected by methyl-beta-cyclodextrin, indicating...... that membrane cholesterol is not required for toxin binding and entry. The ganglioside GM(1) is known as the receptor for CTB, but surprisingly the toxin also bound to sucrase-isomaltase and coclustered with this glycosidase in apical membrane pits. CTB binds to lipid rafts of the brush border...

  6. Fabrication of high-capacity polyelectrolyte brush-grafted porous AAO-silica composite membrane via RAFT polymerization.

    Science.gov (United States)

    Song, Cunfeng; Wang, Meijie; Liu, Xin; Wang, He; Chen, Xiaoling; Dai, Lizong

    2017-09-01

    Surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization has been utilized to fabricate high-capacity strong anion-exchange (AEX) membrane for the separation of protein. By means of RAFT polymerization, quaternized poly(3-(methacrylamidomethyl)-pyridine) brushes formed 3-dimensional nanolayers on the surface of porous anodic aluminum oxide (AAO)-silica composite membrane. The surface properties of the membranes were analyzed by SEM, water contact angle, ATR-FTIR, XPS and TGA. To investigate the adsorption performance, the new AEX membranes were applied to recover a model protein, ovalbumin (OVA). High adsorption capacities of 95.8mg/g membranes (static) and 65.3mg/g membranes (dynamic) were obtained at ambient temperature. In the further studies, up to 90% of the adsorbed OVA was efficiently eluted by using phosphate buffer-1M NaCl as elution medium. The successful separation of OVA with high purity from a mixture protein solution was also achieved by using the AEX membranes. The present study demonstrated that under mild reaction condition, RAFT polymerization can be used to fabricate ion-exchange membrane which has many remarkable features, such as high capacity and selectivity, easy elution and so on. Copyright © 2017. Published by Elsevier B.V.

  7. Hemocompatibility of poly(vinylidene fluoride) membrane grafted with network-like and brush-like antifouling layer controlled via plasma-induced surface PEGylation.

    Science.gov (United States)

    Chang, Yung; Shih, Yu-Ju; Ko, Chao-Yin; Jhong, Jheng-Fong; Liu, Ying-Ling; Wei, Ta-Chin

    2011-05-03

    In this work, the hemocompatibility of PEGylated poly(vinylidene fluoride) (PVDF) microporous membranes with varying grafting coverage and structures via plasma-induced surface PEGylation was studied. Network-like and brush-like PEGylated layers on PVDF membrane surfaces were achieved by low-pressure and atmospheric plasma treatment. The chemical composition, physical morphology, grafting structure, surface hydrophilicity, and hydration capability of prepared membranes were determined to illustrate the correlations between grafting qualities and hemocompatibility of PEGylated PVDF membranes in contact with human blood. Plasma protein adsorption onto different PEGylated PVDF membranes from single-protein solutions and the complex medium of 100% human plasma were measured by enzyme-linked immunosorbent assay (ELISA) with monoclonal antibodies. Hemocompatibility of the PEGylated membranes was evaluated by the antifouling property of platelet adhesion observed by scanning electron microscopy (SEM) and the anticoagulant activity of the blood coagulant determined by testing plasma-clotting time. The control of grafting structures of PEGylated layers highly regulates the PVDF membrane to resist the adsorption of plasma proteins, the adhesion of platelets, and the coagulation of human plasma. It was found that PVDF membranes grafted with brush-like PEGylated layers presented higher hydration capability with binding water molecules than with network-like PEGylated layers to improve the hemocompatible character of plasma protein and blood platelet resistance in human blood. This work suggests that the hemocompatible nature of grafted PEGylated polymers by controlling grafting structures gives them great potential in the molecular design of antithrombogenic membranes for use in human blood.

  8. Bottle-Brush Brushes: Cylindrical Molecular Brushes of Poly(2-oxazoline) on Glassy Carbon

    KAUST Repository

    Zhang, Ning; Steenackers, Marin; Luxenhofer, Robert; Jordan, Rainer

    2009-01-01

    We report on the synthesis of brushes of bottle-brushes of poly(2-oxazoline)s on polished glassy carbon (GC) substrates. First, homogeneous and stable poly(2-isopropenyl-2-oxazoline) (PIPOx) brush layers with thicknesses up to 160 nm were created directly onto GC by the self-initiated photografting and photopolymerization (SIPGP) of 2-isopropenyl-2-oxazoline (IPOx). Kinetic studies reveal a linear increase in thickness with the polymerization time. In a second reaction, the pendant 2-oxazoline ring of the PIPOx brushes were used for the living cationic ring-opening polymerization (LCROP) with different substituted 2-oxazoline monomers to form the side chains. Also for the second surface-initiatedLCROPfrom the surface-bound macroinitiator brushes, the thickness increase with the polymerization time was found to be linear and reproducible. Characterization of the resulting bottle-brush brushes by FTIR spectroscopy,contact angle, and AFM indicates a high side chain grafting density and quantitative reactions. Finally, we have demonstrated the possibility of functionalizing the bottle-brush brushes side chain end groups with sterically demanding molecules. © 2009 American Chemical Society.

  9. Bottle-Brush Brushes: Cylindrical Molecular Brushes of Poly(2-oxazoline) on Glassy Carbon

    KAUST Repository

    Zhang, Ning

    2009-07-28

    We report on the synthesis of brushes of bottle-brushes of poly(2-oxazoline)s on polished glassy carbon (GC) substrates. First, homogeneous and stable poly(2-isopropenyl-2-oxazoline) (PIPOx) brush layers with thicknesses up to 160 nm were created directly onto GC by the self-initiated photografting and photopolymerization (SIPGP) of 2-isopropenyl-2-oxazoline (IPOx). Kinetic studies reveal a linear increase in thickness with the polymerization time. In a second reaction, the pendant 2-oxazoline ring of the PIPOx brushes were used for the living cationic ring-opening polymerization (LCROP) with different substituted 2-oxazoline monomers to form the side chains. Also for the second surface-initiatedLCROPfrom the surface-bound macroinitiator brushes, the thickness increase with the polymerization time was found to be linear and reproducible. Characterization of the resulting bottle-brush brushes by FTIR spectroscopy,contact angle, and AFM indicates a high side chain grafting density and quantitative reactions. Finally, we have demonstrated the possibility of functionalizing the bottle-brush brushes side chain end groups with sterically demanding molecules. © 2009 American Chemical Society.

  10. Surface grafted polymer brushes: potential applications in dengue biosensors

    Energy Technology Data Exchange (ETDEWEB)

    Baratela, Fernando Jose Costa; Higa, Olga Zazuco, E-mail: ozahiga@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Faria, Henrique Antonio Mendonca de; Queiroz, Alvaro Antonio Alencar de, E-mail: alencar@unifei.edu.br [Universidade Federal de Itajuba (UNIFEI), Itajuba, MG (Brazil). Instituto de Fisica e Quimica

    2013-07-01

    A polymer brush membrane-based ultrasensitive biosensor for dengue diagnosis was constructed using poly(hydroxyethyl methacrylate) (PHEMA) brushes immobilized onto low density polyethylene (LDPE) films. LDPE surface films were initially modified by Ar{sup +} ion irradiation to activate the polymer surface. Subsequently, graft polymerization of 2-hydroxyethyl methacrylate onto the activated LDPE surface was carried out under aqueous conditions to create patterned polymer brushes of PHEMA. The grafted PHEMA brushes were characterized by Fourier transform-infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and contact angle analysis. The SEM observations showed that selective surface activation with Ar+ implantation and graft polymerization on the selectively activated surface had occurred. The PHEMA brushes were electrically characterized in the presence of concentrations of human immunoglobulin (IgG). The proposed amperometric biosensor was successfully used for determination of IgG in physiologic samples with excellent responses. (author)

  11. Surface grafted polymer brushes: potential applications in dengue biosensors

    International Nuclear Information System (INIS)

    Baratela, Fernando Jose Costa; Higa, Olga Zazuco; Faria, Henrique Antonio Mendonca de; Queiroz, Alvaro Antonio Alencar de

    2013-01-01

    A polymer brush membrane-based ultrasensitive biosensor for dengue diagnosis was constructed using poly(hydroxyethyl methacrylate) (PHEMA) brushes immobilized onto low density polyethylene (LDPE) films. LDPE surface films were initially modified by Ar + ion irradiation to activate the polymer surface. Subsequently, graft polymerization of 2-hydroxyethyl methacrylate onto the activated LDPE surface was carried out under aqueous conditions to create patterned polymer brushes of PHEMA. The grafted PHEMA brushes were characterized by Fourier transform-infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and contact angle analysis. The SEM observations showed that selective surface activation with Ar+ implantation and graft polymerization on the selectively activated surface had occurred. The PHEMA brushes were electrically characterized in the presence of concentrations of human immunoglobulin (IgG). The proposed amperometric biosensor was successfully used for determination of IgG in physiologic samples with excellent responses. (author)

  12. In vivo antibody-mediated modulation of aminopeptidase A in mouse proximal tubular epithelial cells.

    Science.gov (United States)

    Mentzel, S; Dijkman, H B; van Son, J P; Wetzels, J F; Assmann, K J

    1999-07-01

    Aminopeptidase A (APA) is one of the many renal hydrolases. In mouse kidney, APA is predominantly expressed on the brush borders and sparsely on the basolateral membranes of proximal tubular epithelial cells. However, when large amounts of monoclonal antibodies (MAbs) against APA were injected into mice, we observed strong binding of the MAbs to the basolateral membranes, whereas the MAbs bound only transiently to the brush borders of the proximal tubular epithelial cells. In parallel, APA itself disappeared from the brush borders by both endocytosis and shedding, whereas it was increasingly expressed on the basolateral sides. Using ultrastructural immunohistology, we found no evidence for transcellular transport of endocytosed APA to the basolateral side of the proximal tubular epithelial cells. The absence of transcellular transport was confirmed by experiments in which we used a low dose of the MAbs. Such a low dose did not result in binding of the MAbs to the brush borders and had no effect on the presence of APA in the brush borders of the proximal tubular epithelial cells. In these experiments we still could observe binding of the MAbs to the basolateral membranes in parallel with the local appearance of APA. In addition, treatment of mice with chlorpromazine, a calmodulin antagonist that interferes with cytoskeletal function, largely inhibited the MAb-induced modulation of APA. Our studies suggest that injection of MAbs to APA specifically interrupts the normal intracellular traffic of this enzyme in proximal tubular epithelial cells. This intracellular transport is dependent on the action of cytoskeletal proteins.

  13. Structure of the human vitreoretinal border region

    DEFF Research Database (Denmark)

    Heegaard, Steffen

    1994-01-01

    Øjenpatologi, vitreoretinal border region, inner limiting membrane, retina, topographical variation, human......Øjenpatologi, vitreoretinal border region, inner limiting membrane, retina, topographical variation, human...

  14. Food grade titanium dioxide disrupts intestinal brush border microvilli in vitro independent of sedimentation.

    Science.gov (United States)

    Faust, James J; Doudrick, Kyle; Yang, Yu; Westerhoff, Paul; Capco, David G

    2014-06-01

    Bulk- and nano-scale titanium dioxide (TiO2) has found use in human food products for controlling color, texture, and moisture. Once ingested, and because of their small size, nano-scale TiO2 can interact with a number of epithelia that line the human gastrointestinal tract. One such epithelium responsible for nutrient absorption is the small intestine, whose constituent cells contain microvilli to increase the total surface area of the gut. Using a combination of scanning and transmission electron microscopy it was found that food grade TiO2 (E171 food additive coded) included ∼25% of the TiO2 as nanoparticles (NPs; TiO2 sedimentation. It was found that TiO2 isolated from the candy coating of chewing gum and a commercially available TiO2 food grade additive samples were of the anatase crystal structure. Exposure to food grade TiO2 additives, containing nanoparticles, at the lowest concentration tested within this experimental paradigm to date at 350 ng/mL (i.e., 100 ng/cm(2) cell surface area) resulted in disruption of the brush border. Through the use of two independent techniques to remove the effects of gravity, and subsequent TiO2 sedimentation, it was found that disruption of the microvilli was independent of sedimentation. These data indicate that food grade TiO2 exposure resulted in the loss of microvilli from the Caco-2BBe1 cell system due to a biological response, and not simply a physical artifact of in vitro exposure.

  15. Monoclonal antibodies that bind the renal Na+/glucose symport system. 1. Identification

    International Nuclear Information System (INIS)

    Wu, J.S.R.; Lever, J.E.

    1987-01-01

    Phlorizin is a specific, high-affinity ligand that binds the active site of the Na + /glucose symporter by a Na + -dependent mechanism but is not itself transported across the membrane. The authors have isolated a panel of monoclonal antibodies that influence high-affinity, Na + -dependent phlorizin binding to pig renal brush border membranes. Antibodies were derived after immunization of mice either with highly purified renal brush border membranes or with apical membranes purified from LLC-PK 1 , a cell line of pig renal proximal tubule origin. Antibody 11A3D6, an IgG/sub 2b/, reproducibly stimulated Na + -dependent phlorizin binding whereas antibody 18H10B12, an IgM, strongly inhibited specific binding. These effects were maximal after 30-min incubation and exhibited saturation at increased antibody concentrations. Antibodies did not affect Na + -dependent sugar uptake in vesicles but significantly prevented transport inhibition by bound phlorizin. Antibodies recognized a 75-kDa antigen identified by Western blot analysis of brush border membranes, and a 75-kDa membrane protein could be immunoprecipitated by 18H10B12. These properties, provide compelling evidence that the 75-kDa antigen recognized by these antibodies is a component of the renal Na + /glucose symporter

  16. [Kinetic properties of the fructose influx across the brush border of the rat jejunum. Effects of a diet rich in fructose].

    Science.gov (United States)

    Crouzoulon, G

    1978-10-01

    The unidirectional influx (i.e. initial rate of uptake) of D-fructose across the brush border of rat jejunum is a saturable function of concentration, with a Kt of 125 mM, which implicates a carrier mechanism. This mechanism appears to be very specific for fructose in view of the lack of influx inhibition observed in the presence of large concentrations of the sugars or polyols, D-glucose, D-galactose, D-mannose, D-xylose, L-sorbose, D-tagatose, sorbitol or mannitol. D-Fructose uptake is inhibited by incubation, preceded by a 30-min preincubation in the same inhibitory conditions, in the absence of Na, or in the presence of metabolic poisons, NaF, 2,4-dinitrophenol, monoiodoacetate. Phloridzin (10-3 M), with or without preincubation, has no effect on uptake. D-Fructose influx is stimulated by fructose feeding, mainly because the augmentation of the number of active sites of transfer: Jmax is increased two-fold, Kt is more weakly affected.

  17. Structure of the animal vitreoretinal border region

    DEFF Research Database (Denmark)

    Heegaard, Steffen

    1994-01-01

    Øjenpatologi, vitreoretinal border region, inner limiting membrane of the retina, animals, ultrastructure, comparative anatomy......Øjenpatologi, vitreoretinal border region, inner limiting membrane of the retina, animals, ultrastructure, comparative anatomy...

  18. Mapping the membrane-aqueous border for the voltage-sensing domain of a potassium channel.

    Science.gov (United States)

    Neale, Edward J; Rong, Honglin; Cockcroft, Christopher J; Sivaprasadarao, Asipu

    2007-12-28

    Voltage-sensing domains (VSDs) play diverse roles in biology. As integral components, they can detect changes in the membrane potential of a cell and couple these changes to activity of ion channels and enzymes. As independent proteins, homologues of the VSD can function as voltage-dependent proton channels. To sense voltage changes, the positively charged fourth transmembrane segment, S4, must move across the energetically unfavorable hydrophobic core of the bilayer, which presents a barrier to movement of both charged species and protons. To reduce the barrier to S4 movement, it has been suggested that aqueous crevices may penetrate the protein, reducing the extent of total movement. To investigate this hypothesis in a system containing fully functional channels in a native environment with an intact membrane potential, we have determined the contour of the membrane-aqueous border of the VSD of KvAP in Escherichia coli by examining the chemical accessibility of introduced cysteines. The results revealed the contour of the membrane-aqueous border of the VSD in its activated conformation. The water-inaccessible regions of S1 and S2 correspond to the standard width of the membrane bilayer (~28 A), but those of S3 and S4 are considerably shorter (> or = 40%), consistent with aqueous crevices pervading both the extracellular and intracellular ends. One face of S3b and the entire S3a were water-accessible, reducing the water-inaccessible region of S3 to just 10 residues, significantly shorter than for S4. The results suggest a key role for S3 in reducing the distance S4 needs to move to elicit gating.

  19. Electrospun regenerated cellulose nanofibrous membranes surface-grafted with polymer chains/brushes via the atom transfer radical polymerization method for catalase immobilization.

    Science.gov (United States)

    Feng, Quan; Hou, Dayin; Zhao, Yong; Xu, Tao; Menkhaus, Todd J; Fong, Hao

    2014-12-10

    In this study, an electrospun regenerated cellulose (RC) nanofibrous membrane with fiber diameters of ∼200-400 nm was prepared first; subsequently, 2-hydroxyethyl methacrylate (HEMA), 2-dimethylaminoethyl methacrylate (DMAEMA), and acrylic acid (AA) were selected as the monomers for surface grafting of polymer chains/brushes via the atom transfer radical polymerization (ATRP) method. Thereafter, four nanofibrous membranes (i.e., RC, RC-poly(HEMA), RC-poly(DMAEMA), and RC-poly(AA)) were explored as innovative supports for immobilization of an enzyme of bovine liver catalase (CAT). The amount/capacity, activity, stability, and reusability of immobilized catalase were evaluated, and the kinetic parameters (Vmax and Km) for immobilized and free catalase were determined. The results indicated that the respective amounts/capacities of immobilized catalase on RC-poly(HEMA) and RC-poly(DMAEMA) nanofibrous membranes reached 78 ± 3.5 and 67 ± 2.7 mg g(-1), which were considerably higher than the previously reported values. Meanwhile, compared to that of free CAT (i.e., 18 days), the half-life periods of RC-CAT, RC-poly(HEMA)-CAT, RC-poly(DMAEMA)-CAT, and RC-poly(AA)-CAT were 49, 58, 56, and 60 days, respectively, indicating that the storage stability of immobilized catalase was also significantly improved. Furthermore, the immobilized catalase exhibited substantially higher resistance to temperature variation (tested from 5 to 70 °C) and lower degree of sensitivity to pH value (tested from 4.0 and 10.0) than the free catalase. In particular, according to the kinetic parameters of Vmax and Km, the nanofibrous membranes of RC-poly(HEMA) (i.e., 5102 μmol mg(-1) min(-1) and 44.89 mM) and RC-poly(DMAEMA) (i.e., 4651 μmol mg(-1) min(-1) and 46.98 mM) had the most satisfactory biocompatibility with immobilized catalase. It was therefore concluded that the electrospun RC nanofibrous membranes surface-grafted with 3-dimensional nanolayers of polymer chains/brushes would be

  20. Microimaging of Bacillus thuringiensis Toxin-binding proteins in gypsy moth larval gut using confocal fluorescence microscopy

    Science.gov (United States)

    Daniel J. Krofcheck; Algimantas P. Valaitis

    2010-01-01

    After ingestion by susceptible insect larvae, Bacillus thuringiensis (Bt) insecticidal proteins bind to the brush border membranes of gut epithelial cells and disrupt the integrity of the plasma membrane by forming...

  1. Further characterization of intestinal lactase/phlorizin hydrolase

    DEFF Research Database (Denmark)

    Skovbjerg, H; Norén, O; Sjöström, H

    1982-01-01

    Pig intestinal lactase/phlorizin hydrolase (EC 3.2.1.23/62) was purified in its amphiphilic form by immunoadsorbent chromatography. The purified enzyme was free of other known brush border enzymes and appeared homogeneous in immunoelectrophoresis and polyacrylamide gel electrophoresis in the pres......Pig intestinal lactase/phlorizin hydrolase (EC 3.2.1.23/62) was purified in its amphiphilic form by immunoadsorbent chromatography. The purified enzyme was free of other known brush border enzymes and appeared homogeneous in immunoelectrophoresis and polyacrylamide gel electrophoresis...... in the presence of SDS. Pig lactase/phlorizin hydrolase was shown to have the same quaternary structure as the human enzyme, i.e., built up of two polypeptides of the same molecular weight (160000). In addition to hydrolyzing lactose, phlorizin and a number of synthetic substrates, both the human and the pig...... membranes (basolateral and intracellular membranes) exhibited in SDS-polyacrylamide gel electrophoresis the same size of constituent polypeptides and the same catalytic and immunological properties as a normal brush border lactase/phlorizin hydrolase....

  2. Effect of nephrotoxicants on renal membrane transport: In vitro studies

    International Nuclear Information System (INIS)

    Ansari, R.A.; Berndt, W.O.

    1990-01-01

    It is possible to study the effects of nephrotoxicants on membrane function free of other cellular influences. By the use of Percoll gradient centrifugation, highly purified preparations of right-side-out basolateral (BL) and brush border (BB) membrane vesicles can be obtained from rat (male, Sprague-Dawley) renal cortex. Membrane function can be monitored by evaluation of sodium driven transport: 14 C-p-aminohippurate (PAH) for BL and 14 C-glucose for BB. Transport was measured by the rapid filtration technique. Each vesicle preparation was preincubated with the nephrotoxicant for five minutes before initiation of transport. Control vesicles showed a prominant overshoot 1 to 2 minutes after start of transport. Mercuric ion (Hg) had no effect on transport by BB at concentrations as high as 10μM. Transport by BL was reduced significantly at Hg concentrations as low as 100 nM. Chromate (Cr) also reduced BL transport at 100 nM and had no effect on BB transport. Citrinin significantly reduced both BB and BL transport, but the sensitivity of the membrane preparations differed. These data are consistent with the hypothesis that some nephrotoxicants may act on either side of the renal tubular cell membrane

  3. Improved surface property of PVDF membrane with amphiphilic zwitterionic copolymer as membrane additive

    Energy Technology Data Exchange (ETDEWEB)

    Li Jianhua, E-mail: jhli_2005@163.com [Institute of Biomedical and Pharmaceutical Technology and College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350001 (China); Li Mizi; Miao Jing; Wang Jiabin; Shao Xisheng [Institute of Biomedical and Pharmaceutical Technology and College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350001 (China); Zhang Qiqing, E-mail: zhangqiq@126.com [Institute of Biomedical and Pharmaceutical Technology and College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350001 (China) and Institute of Biomedical Engineering, Chinese Academy of Medical Science, Peking Union Medical College, Tianjin 300192 (China)

    2012-06-15

    An attempt to improve hydrophilicity and anti-fouling properties of PVDF membranes, a novel amphiphilic zwitterionic copolymer poly(vinylidene fluoride)-graft-poly(sulfobetaine methacrylate) (PVDF-g-PSBMA) was firstly synthesized by atom transfer radical polymerization (ATRP) and used as amphiphilic copolymer additive in the preparation of PVDF membranes. The PVDF-g-PSBMA/PVDF blend membranes were prepared by immersion precipitation process. Fourier transform infrared attenuated reflection spectroscopy (FTIR-ATR) and X-ray photoelectronic spectroscopy (XPS) measurements confirmed that PSBMA brushes from amphiphilic additives were preferentially segregated to membrane-coagulant interface during membrane formation. The morphology of membranes was characterized by scanning electron microscopy (SEM). Water contact angle measurements showed that the surface hydrophilicity of PVDF membranes was improved significantly with the increasing of amphiphilic copolymer PVDF-g-PSBMA in cast solution. Protein static adsorption experiment and dynamic fouling resistance experiment revealed that the surface enrichment of PSBMA brush endowed PVDF blend membrane great improvement of surface anti-fouling ability.

  4. Improved surface property of PVDF membrane with amphiphilic zwitterionic copolymer as membrane additive

    International Nuclear Information System (INIS)

    Li Jianhua; Li Mizi; Miao Jing; Wang Jiabin; Shao Xisheng; Zhang Qiqing

    2012-01-01

    An attempt to improve hydrophilicity and anti-fouling properties of PVDF membranes, a novel amphiphilic zwitterionic copolymer poly(vinylidene fluoride)-graft-poly(sulfobetaine methacrylate) (PVDF-g-PSBMA) was firstly synthesized by atom transfer radical polymerization (ATRP) and used as amphiphilic copolymer additive in the preparation of PVDF membranes. The PVDF-g-PSBMA/PVDF blend membranes were prepared by immersion precipitation process. Fourier transform infrared attenuated reflection spectroscopy (FTIR-ATR) and X-ray photoelectronic spectroscopy (XPS) measurements confirmed that PSBMA brushes from amphiphilic additives were preferentially segregated to membrane-coagulant interface during membrane formation. The morphology of membranes was characterized by scanning electron microscopy (SEM). Water contact angle measurements showed that the surface hydrophilicity of PVDF membranes was improved significantly with the increasing of amphiphilic copolymer PVDF-g-PSBMA in cast solution. Protein static adsorption experiment and dynamic fouling resistance experiment revealed that the surface enrichment of PSBMA brush endowed PVDF blend membrane great improvement of surface anti-fouling ability.

  5. Improved antifouling properties of polymer membranes using a ‘layer-by-layer’ mediated method

    KAUST Repository

    Chen, Lin

    2013-01-01

    Polymeric reverse osmosis membranes were modified with antifouling polymer brushes through a \\'layer by layer\\' (LBL) mediated method. Based on pure physical electrostatic interaction, the attachment of LBL films did not alter separation performance of the membranes. In addition, the incorporation of an LBL film also helped to amplify the number of potential reaction sites on the membrane surfaces for attachment of antifouling polymer brushes, which were then attached to the surface. Attachment of the brushes included two different approaches, grafting to and grafting from. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and water contact angle measurements showed successful growth of the LBL films and subsequently the polymer brushes. Using this method to modify reverse osmosis membranes, preliminary performance testing showed the antifouling properties of the as-modified membranes were much better than the virgin membrane with no significant loss in water flux and salt rejection. © 2013 The Royal Society of Chemistry.

  6. Polymer Brushes

    NARCIS (Netherlands)

    Vos, de W.M.; Kleijn, J.M.; Keizer, de A.; Cosgrove, T.; Cohen Stuart, M.A.

    2010-01-01

    A polymer brush can be defined as a dense array of polymers end-attached to an interface that stretch out into the surrounding medium. Polymer brushes have been investigated for the past 30 years and have shown to be an extremely useful tool to control interfacial properties. This review is intended

  7. Biomolecule-functionalized polymer brushes.

    Science.gov (United States)

    Jiang, Hui; Xu, Fu-Jian

    2013-04-21

    Functional polymer brushes have been utilized extensively for the immobilization of biomolecules, which is of crucial importance for the development of biosensors and biotechnology. Recent progress in polymerization methods, in particular surface-initiated atom transfer radical polymerization (ATRP), has provided a unique means for the design and synthesis of new biomolecule-functionalized polymer brushes. This current review summarizes such recent research activities. The different preparation strategies for biomolecule immobilization through polymer brush spacers are described in detail. The functional groups of the polymer brushes used for biomolecule immobilization include epoxide, carboxylic acid, hydroxyl, aldehyde, and amine groups. The recent research activities indicate that functional polymer brushes become versatile and powerful spacers for immobilization of various biomolecules to maximize their functionalities. This review also demonstrates that surface-initiated ATRP is used more frequently than other polymerization methods in the designs of new biomolecule-functionalized polymer brushes.

  8. Stratified polymer brushes from microcontact printing of polydopamine initiator on polymer brush surfaces.

    Science.gov (United States)

    Wei, Qiangbing; Yu, Bo; Wang, Xiaolong; Zhou, Feng

    2014-06-01

    Stratified polymer brushes are fabricated using microcontact printing (μCP) of initiator integrated polydopamine (PDOPBr) on polymer brush surfaces and the following surface initiated atom transfer radical polymerization (SI-ATRP). It is found that the surface energy, chemically active groups, and the antifouling ability of the polymer brushes affect transfer efficiency and adhesive stability of the polydopamine film. The stickiness of the PDOPBr pattern on polymer brush surfaces is stable enough to perform continuous μCP and SI-ATRP to prepare stratified polymer brushes with a 3D topography, which have broad applications in cell and protein patterning, biosensors, and hybrid surfaces. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Intestinal epithelial cell surface glycosylation in mice. I. Effect of high-protein diet.

    Science.gov (United States)

    Gupta, R; Jaswal, V M; Meenu Mahmood, A

    1992-01-01

    The effects of variation in dietary protein content have been investigated on brush border glycosylation and enzyme activities in mice small intestine. The comparison of different parameters was made between the mice fed 30% (high protein, HP) and 18% protein (pair-fed, PF, and ad libitum-fed) for 21 days. The activities of brush border sucrase, lactase, p-nitrophenyl (PNP)-beta-D-glucosidase and PNP-beta-D-galactosidase were reduced in the HP diet-fed mice compared to PF and ad libitum-fed controls. Alkaline phosphatase and leucine amino-peptidase activities were significantly enhanced while gamma-glutamyl transpeptidase activity was unaltered under these conditions. Total hexoses and sialic acid content in the brush borders were reduced significantly in the test group compared to the controls while hexosamine and fucose contents remained essentially similar in different groups. The results on the binding of wheat germ agglutinin and Ulex europaeus agglutininI to microvillus membranes corroborated the chemical analysis data on sialic acid and fucose contents of the membranes. Peanut agglutinin binding was enhanced in mice from the HP group. Incorporation of (14C)-mannose into membranes was significantly less in HP diet-fed mice. These results indicate that the feeding of HP diet to mice brings about marked alterations in small intestinal epithelial cell surface glycosylation and enzyme functions.

  10. Effects of cashew nut shell liquid (CNSL) component upon Aedes ...

    African Journals Online (AJOL)

    ... cells from the basal membrane, and disintegration of the brush border and damage of the peritrophic membrane occurred. CNSL caused damage to the midgut of 3rd instars of A. aegypti by irreversibly disrupting their complete larval development. Key words: Dengue fever, bioinsecticids from plants, morfology of midgut ...

  11. ``Smart'' Surfaces of Polymer Brushes

    Science.gov (United States)

    Wang, Qiang; Meng, Dong

    2009-03-01

    ``Smart'' surfaces, also known as stimuli-responsive surfaces, can change their properties (e.g., wettability, adhesion, friction, elasticity, and biocompatibility) in response to external stimuli (e.g., temperature, pressure, light, solvent selectivity, ionic strength, type of salt, pH, applied electric field, etc.). In this work, we use numerical self-consistent field calculations to study in detail the structure and stimuli- responses of various polymer brushes, including (1) the thermo- response of PNIPAM brushes in water, (2) solvent-response of uncharged diblock copolymer brushes, and (3) the stimuli- response of charged two-component polymer brushes (including both the binary A/B brushes and diblock copolymer A-B brushes) to ionic strength, pH, and applied electric field. Among the many design parameters (e.g., chain lengths, grafting densities, A-B incompatibility, degree of ionization of charged polymers, etc.) we identify those that strongly affect the surface switchability. Such knowledge is useful to the experimental design of these smart polymer brushes for their applications.

  12. Structure of the vitreoretinal border region in spontaneously hypertensive rats (SHR rats)

    DEFF Research Database (Denmark)

    Heegaard, Steffen

    1993-01-01

    Øjenpatologi, vitreoretinal border region, inner limiting membrane of the retina, spontaneously hypertensive rats, SHR rats, ultrastructure......Øjenpatologi, vitreoretinal border region, inner limiting membrane of the retina, spontaneously hypertensive rats, SHR rats, ultrastructure...

  13. Localization of Bacillus thuringiensis Cry1A toxin-binding molecules in gypsy moth larval gut sections using fluorescence microscopy

    Science.gov (United States)

    Algimantas P. Valaitis

    2011-01-01

    The microbial insecticide Bacillus thuringiensis (Bt) produces Cry toxins, proteins that bind to the brush border membranes of gut epithelial cells of insects that ingest it, disrupting the integrity of the membranes, and leading to cell lysis and insect death. In gypsy moth, Lymantria dispar, two toxin-binding molecules for the...

  14. Adaptation of intestinal hydrolases to starvation in rats: effect of thyroid function

    DEFF Research Database (Denmark)

    Galluser, M; Belkhou, R; Freund, J N

    1991-01-01

    The effects of long-term starvation on the activities of sucrase, lactase, and aminopeptidase, and on their respective mRNA were determined in the small intestine of thyroidectomized and sham-operated adult rats. Thyroidectomy reduced the protein loss at the level of the intestinal brush border...... membranes during starvation. Prolonged fasting caused a significant decrease in sucrase activity, but thyroidectomy partly prevented this effect. However, the amount of the corresponding mRNA dropped during long term starvation without incidence of thyroidectomy. Lactase activity in the brush border...... membranes was increased by starvation, and thyroidectomy caused a further elevation of the enzyme activity. Simultaneously, lactase mRNA content rose only slightly compared to the enzyme activity. Aminopeptidase activity and mRNA content decreased during starvation and thyroidectomy did not prevent...

  15. Water Soluble Responsive Polymer Brushes

    Directory of Open Access Journals (Sweden)

    Andrew J. Parnell

    2011-12-01

    Full Text Available Responsive polymer brushes possess many interesting properties that enable them to control a range of important interfacial behaviours, including adhesion, wettability, surface adsorption, friction, flow and motility. The ability to design a macromolecular response to a wide variety of external stimuli makes polymer brushes an exciting class of functional materials, and has been made possible by advances in modern controlled polymerization techniques. In this review we discuss the physics of polymer brush response along with a summary of the techniques used in their synthesis. We then review the various stimuli that can be used to switch brush conformation; temperature, solvent quality, pH and ionic strength as well as the relatively new area of electric field actuation We discuss examples of devices that utilise brush conformational change, before highlighting other potential applications of responsive brushes in real world devices.

  16. Brush head composition, wear profile, and cleaning efficacy: an assessment of three electric brush heads using in vitro methods.

    Science.gov (United States)

    Kaiser, Eva; Meyners, Michael; Markgraf, Dirk; Stoerkel, Ulrich; von Koppenfels, Roxana; Adam, Ralf; Soukup, Martin; Wehrbein, Heinrich; Erbe, Christina

    2014-01-01

    The objective of this research was to evaluate a current store brand (SB) brush head for composition/physical characteristics, Wear Index (WI), and cleaning efficacy versus the previous SB brush head refill design (SB control) and the Oral-B Precision Clean brush head (positive control, PC). This research consisted of three parts: 1) Analytical analysis using Fourier Transform Infrared (FT-IR) spectrometry to evaluate the chemical composition of the current SB brush head bristles relative to the SB control. In addition, physical parameters such as bristle count and diameter were determined. 2) Wear Index (WI) investigation to determine the Wear Index scores of in vitro-aged brush heads at four weeks (one month) and 13 weeks (three months) by a trained investigator. To "age" the brush heads, a robot system was used as a new alternative in vitro method to simulate aging by consumer use. 3) Robot testing to determine the cleaning performance of in vitro-aged brush heads, comparing one month-aged current SB brush heads with the SB control (one and three months-aged) and the PC brush heads (three months-aged) in a standardized fashion. 1) FT-IR analysis revealed that the chemical composition of the current and control SB refill brush heads is identical. In terms of physical parameters, the current SB brush head has 12% more bristles and a slightly oval brush head compared to the round brush head of the SB control. 2) Wear Index analysis showed there was no difference in the one month-aged current SB brush head versus the one month-aged SB control (1.67 vs. 1.50, p = 0.65) or versus the three months-aged PC brush head (1.67 vs. 1.50, p = 0.65). The one month-aged current SB brush head demonstrated statistically significantly less wear than the three months-aged SB control (1.67 vs. 2.67, p = 0.01). 3) Analysis of cleaning efficacy shows that the one month-aged current SB brush head had improved cleaning performance over the one month-aged SB control brush head (p < 0

  17. AFM-based force spectroscopy on polystyrene brushes: effect of brush thickness on protein adsorption.

    Science.gov (United States)

    Hentschel, Carsten; Wagner, Hendrik; Smiatek, Jens; Heuer, Andreas; Fuchs, Harald; Zhang, Xi; Studer, Armido; Chi, Lifeng

    2013-02-12

    Herein we present a study on nonspecific binding of proteins at highly dense packed hydrophobic polystyrene brushes. In this context, an atomic force microscopy tip was functionalized with concanavalin A to perform single-molecule force spectroscopy measurements on polystyrene brushes with thicknesses of 10 and 60 nm, respectively. Polystyrene brushes with thickness of 10 nm show an almost two times stronger protein adsorption than brushes with a thickness of 60 nm: 72 pN for the thinner and 38 pN for the thicker layer, which is in qualitative agreement with protein adsorption studies conducted macroscopically by fluorescence microscopy.

  18. Tyrosine transport in winter flounder intestine: Interaction with Na+-K+-2Cl- cotransport

    International Nuclear Information System (INIS)

    Musch, M.W.; McConnell, F.M.; Goldstein, L.; Field, M.

    1987-01-01

    Tyrosine absorption across the brush border of the intestinal epithelium of the winter flounder Pseudopleuronectes americanus was studied in Ussing chambers modified to determine early rates of uptake. At 0.1 mM tyrosine, the 4-min rate of uptake (influx) of tyrosine across the brush border averaged 37.5 nmol·cm -2 ·h -1 . Omission of Na decreased influx by 60%, indicting that tyrosine influx occurs, at least in part, by a Na-coupled process. Ouabain inhibited influx by 80%. Inhibition of brush border Na + -K + -2Cl - cotransport by bumetanide, 8-bromo-cyclic GMP, or Cl replacement stimulated tyrosine influx 2.5- to 4-fold. However, atriopeptin III, which also inhibits Na + -K + -2Cl - cotransport, did not stimulate tyrosine influx. Cyclic AMP, which does not appear to inhibit ion cotransport, did not stimulate tyrosine influx. Both cyclic GMP and bumetanide also stimulated the net mucosa-to-serosa tyrosine flux (43 and 29%, respectively) and increased the cellular concentration of tyrosine by 50%. Thus tyrosine's influx is increased to a greater extent than is its transmural flux or its cellular concentration, suggesting that the main change occurs at the brush border and represents large increases in both influx and efflux of tyrosine across this membrane

  19. Local pH domains regulate NHE3-mediated Na+ reabsorption in the renal proximal tubule

    Science.gov (United States)

    Burford, James L.; McDonough, Alicia A.; Holstein-Rathlou, Niels-Henrik; Peti-Peterdi, Janos

    2014-01-01

    The proximal tubule Na+/H+ exchanger 3 (NHE3), located in the apical dense microvilli (brush border), plays a major role in the reabsorption of NaCl and water in the renal proximal tubule. In response to a rise in blood pressure NHE3 redistributes in the plane of the plasma membrane to the base of the brush border, where NHE3 activity is reduced. This NHE3 redistribution is assumed to provoke pressure natriuresis; however, it is unclear how NHE3 redistribution per se reduces NHE3 activity. To investigate if the distribution of NHE3 in the brush border can change the reabsorption rate, we constructed a spatiotemporal mathematical model of NHE3-mediated Na+ reabsorption across a proximal tubule cell and compared the model results with in vivo experiments in rats. The model predicts that when NHE3 is localized exclusively at the base of the brush border, it creates local pH microdomains that reduce NHE3 activity by >30%. We tested the model's prediction experimentally: the rat kidney cortex was loaded with the pH-sensitive fluorescent dye BCECF, and cells of the proximal tubule were imaged in vivo using confocal fluorescence microscopy before and after an increase of blood pressure by ∼50 mmHg. The experimental results supported the model by demonstrating that a rise of blood pressure induces the development of pH microdomains near the bottom of the brush border. These local changes in pH reduce NHE3 activity, which may explain the pressure natriuresis response to NHE3 redistribution. PMID:25298526

  20. Polyethyleneimine brushes effectively inhibit encrustation on polyurethane ureteral stents both in dynamic bioreactor and in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Gultekinoglu, Merve [Department of Basic Pharmaceutical Sciences, Faculty of Pharmacy, Hacettepe University, Ankara 06100 (Turkey); Bioengineering Division, Institute for Graduate Studies in Science and Engineering, Hacettepe University, Ankara 06532 (Turkey); Kurum, Barış [Department of Surgery, Faculty of Veterinary Medicine, Kırıkkale University, Kırıkkale 71450 (Turkey); Karahan, Siyami [Department of Histology and Embryology, Faculty of Veterinary Medicine, Kırıkkale University, Kırıkkale 71450 (Turkey); Kart, Didem; Sagiroglu, Meral [Department of Pharmaceutical Microbiology, Faculty of Pharmacy, Hacettepe University, Ankara 06100 (Turkey); Ertaş, Nusret [Department of Analytical Chemistry, Faculty of Pharmacy, Gazi University, Ankara 06330 (Turkey); Haluk Ozen, A. [Department of Urology, Faculty of Medicine, Hacettepe University, Ankara 06100 (Turkey); Ulubayram, Kezban, E-mail: ukezban@hacettepe.edu.tr [Department of Basic Pharmaceutical Sciences, Faculty of Pharmacy, Hacettepe University, Ankara 06100 (Turkey); Bioengineering Division, Institute for Graduate Studies in Science and Engineering, Hacettepe University, Ankara 06532 (Turkey)

    2017-02-01

    Polyurethane (PU) ureteral stents have been widely used as biomedical devices to aid the flow of the urine. Due to the biofilm formation and encrustation complications it has been hindered their long term clinical usage. To overcome these complications, in this study, cationic polyethyleneimine (PEI) brushes grafted on PU stents and their performances were tested both in a dynamic biofilm reactor system (in vitro) and in a rat model (in vivo). Thus, we hypothesized that PEI brushes inhibit bacterial adhesion owing to the dynamic motion of brushes in liquid environment. In addition, cationic structure of PEI disrupts the membrane and so kills the bacteria on time of contact. Cationic PEI brushes decreased the biofilm formation up to 2 orders of magnitude and approximately 50% of encrustation amount in respect to unmodified PU, in vitro. In addition, according to Atomic Absorption Spectroscopy (AAS) results, approximately 90% of encrustation was inhibited on in vivo animal models. Decrease in encrustation was clearly observed on the stents obtained from rat model, by Scanning Electron Microscopy (SEM). Also, histological evaluations showed that; PEI brush grafting decreased host tissue inflammation in close relation to decrease in biofilm formation and encrustation. As a results; dual effect of anti-adhesive and contact-killing antibacterial strategy showed high efficiency on PEI brushes grafted PU stents both in vitro and in vivo.

  1. Polyethyleneimine brushes effectively inhibit encrustation on polyurethane ureteral stents both in dynamic bioreactor and in vivo

    International Nuclear Information System (INIS)

    Gultekinoglu, Merve; Kurum, Barış; Karahan, Siyami; Kart, Didem; Sagiroglu, Meral; Ertaş, Nusret; Haluk Ozen, A.; Ulubayram, Kezban

    2017-01-01

    Polyurethane (PU) ureteral stents have been widely used as biomedical devices to aid the flow of the urine. Due to the biofilm formation and encrustation complications it has been hindered their long term clinical usage. To overcome these complications, in this study, cationic polyethyleneimine (PEI) brushes grafted on PU stents and their performances were tested both in a dynamic biofilm reactor system (in vitro) and in a rat model (in vivo). Thus, we hypothesized that PEI brushes inhibit bacterial adhesion owing to the dynamic motion of brushes in liquid environment. In addition, cationic structure of PEI disrupts the membrane and so kills the bacteria on time of contact. Cationic PEI brushes decreased the biofilm formation up to 2 orders of magnitude and approximately 50% of encrustation amount in respect to unmodified PU, in vitro. In addition, according to Atomic Absorption Spectroscopy (AAS) results, approximately 90% of encrustation was inhibited on in vivo animal models. Decrease in encrustation was clearly observed on the stents obtained from rat model, by Scanning Electron Microscopy (SEM). Also, histological evaluations showed that; PEI brush grafting decreased host tissue inflammation in close relation to decrease in biofilm formation and encrustation. As a results; dual effect of anti-adhesive and contact-killing antibacterial strategy showed high efficiency on PEI brushes grafted PU stents both in vitro and in vivo.

  2. Antifouling Properties of Fluoropolymer Brushes toward Organic Polymers: The Influence of Composition, Thickness, Brush Architecture, and Annealing.

    Science.gov (United States)

    Wang, Zhanhua; Zuilhof, Han

    2016-07-05

    Fluoropolymer brushes are widely used to prevent nonspecific adsorption of commercial polymeric or biological materials due to their strongly hydrophobic character. Herein, a series of fluoropolymer brushes with different compositions, thicknesses and molecular architectures was prepared via surface-initiated atom transfer radical polymerization (ATRP). Subsequently, the antifouling properties of these fluoropolymer brushes against organic polymers were studied in detail using X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) measurements and polystyrene as a representative fouling polymer. Among all of the molecular architectures studied, homopolymerized methacrylate-based fluoropolymer brushes (PMAF17) show the best antifouling properties. Annealing the fluoropolymer brushes improves the antifouling property dramatically due to the reregulated surface composition. These fluoropolymer brushes can be combined with, e.g., micro- and nanostructuring and other advanced materials properties to yield even better long-term antifouling behavior under harsh environments.

  3. Slow brushing reduces heat pain in humans.

    Science.gov (United States)

    Liljencrantz, J; Strigo, I; Ellingsen, D M; Krämer, H H; Lundblad, L C; Nagi, S S; Leknes, S; Olausson, H

    2017-08-01

    C-tactile (CT) afferents are unmyelinated low-threshold mechanoreceptors optimized for signalling affective, gentle touch. In three separate psychophysical experiments, we examined the contribution of CT afferents to pain modulation. In total, 44 healthy volunteers experienced heat pain and CT optimal (slow brushing) and CT sub-optimal (fast brushing or vibration) stimuli. Three different experimental paradigms were used: Concurrent application of heat pain and tactile (slow brushing or vibration) stimulation; Slow brushing, applied for variable duration and intervals, preceding heat pain; Slow versus fast brushing preceding heat pain. Slow brushing was effective in reducing pain, whereas fast brushing or vibration was not. The reduction in pain was significant not only when the CT optimal touch was applied simultaneously with the painful stimulus but also when the two stimuli were separated in time. For subsequent stimulation, the pain reduction was more pronounced for a shorter time interval between brushing and pain. Likewise, the effect was more robust when pain was preceded by a longer duration of brush stimulation. Strong CT-related pain reduction was associated with low anxiety and high calmness scores obtained by a state anxiety questionnaire. Slow brushing - optimal for CT activation - is effective in reducing pain from cutaneous heating. The precise mechanisms for the pain relief are as yet unknown but possible mechanisms include inhibition of nociceptive projection neurons at the level of the dorsal horn as well as analgesia through cortical mechanisms. Slow brushing stimuli - optimal for activation of C-tactile fibres - can reduce pain from cutaneous heating. No such effect was seen with fast brushing or vibration. These observations indicate the role of C-tactile fibres in pain modulation. © 2017 European Pain Federation - EFIC®.

  4. Stimuli-Responsive Polyelectrolyte Brushes As a Matrix for the Attachment of Gold Nanoparticles: The Effect of Brush Thickness on Particle Distribution

    Directory of Open Access Journals (Sweden)

    Stephanie Christau

    2014-06-01

    Full Text Available The effect of brush thickness on the loading of gold nanoparticles (AuNPs within stimuli-responsive poly-(N,N-(dimethylamino ethyl methacrylate (PDMAEMA polyelectrolyte brushes is reported. Atom transfer radical polymerization (ATRP was used to grow polymer brushes via a “grafting from” approach. The brush thickness was tuned by varying the polymerization time. Using a new type of sealed reactor, thick brushes were synthesized. A systematic study was performed by varying a single parameter (brush thickness, while keeping all other parameters constant. AuNPs of 13 nm in diameter were attached by incubation. X-ray reflectivity, electron scanning microscopy and ellipsometry were used to study the particle loading, particle distribution and interpenetration of the particles within the brush matrix. A model for the structure of the brush/particle hybrids was derived. The particle number densities of attached AuNPs depend on the brush thickness, as do the optical properties of the hybrids. An increasing particle number density was found for increasing brush thickness, due to an increased surface roughness.

  5. Role of transporters in placental transfer of drugs

    International Nuclear Information System (INIS)

    Ganapathy, Vadivel; Prasad, Puttur D.

    2005-01-01

    Human placenta functions as an important transport organ that mediates the exchange of nutrients and metabolites between maternal and fetal circulations. This function is made possible because of the expression of a multitude of transport proteins in the placental syncytiotrophoblast with differential localization in the maternal-facing brush border membrane versus the fetal-facing basal membrane. Even though the physiological role of most of these transport proteins is to handle nutrients, many of them interact with xenobiotics and pharmacological agents. These transport proteins therefore play a critical role in the disposition of drugs across the maternal-fetal interface, with some transporters facilitating the entry of drugs from maternal circulation into fetal circulation whereas others preventing such entry by actively eliminating drugs from the placenta back into maternal circulation. The net result as to whether the placenta enhances the exposure of the developing fetus to drugs and xenobiotics or functions as a barrier to protect the fetus from such agents depends on the types of transporters expressed in the brush border membrane and basal membrane of the syncytiotrophoblast and on the functional mode of these transporters (influx versus efflux)

  6. Anthrax Cases Associated with Animal-Hair Shaving Brushes.

    Science.gov (United States)

    Szablewski, Christine M; Hendricks, Kate; Bower, William A; Shadomy, Sean V; Hupert, Nathaniel

    2017-05-01

    During the First World War, anthrax cases in the United States and England increased greatly and seemed to be associated with use of new shaving brushes. Further investigation revealed that the source material and origin of shaving brushes had changed during the war. Cheap brushes of imported horsehair were being made to look like the preferred badger-hair brushes. Unfortunately, some of these brushes were not effectively disinfected and brought with them a nasty stowaway: Bacillus anthracis. A review of outbreak summaries, surveillance data, and case reports indicated that these cases originated from the use of ineffectively disinfected animal-hair shaving brushes. This historical information is relevant to current public health practice because renewed interest in vintage and animal-hair shaving brushes has been seen in popular culture. This information should help healthcare providers and public health officials answer questions on this topic.

  7. Interaction between two polyelectrolyte brushes.

    Science.gov (United States)

    Kumar, N Arun; Seidel, Christian

    2007-08-01

    We report molecular dynamics simulations on completely charged polyelectrolyte brushes grafted to two parallel surfaces. The pressure Pi is evaluated as a function of separation D between the two grafting planes. For decreasing separation, Pi shows several regimes distinguished by their scaling with D which reflects the different physical nature of the various regimes. At weak compression the pressure obeys the 1D power law predicted by scaling theory of an ideal gas of counterions in the osmotic brush regime. In addition we find that the brushes shrink as they approach each other trying to avoid interpenetration. At higher compressions where excluded volume interactions become important, we obtain scaling exponents between -2 at small grafting density rho(a) and -3 at large rho(a). This behavior indicates a transition from a brush under good solvent condition to the melt regime with increasing grafting density.

  8. A randomized clinical trial evaluating gingivitis and plaque reduction of an oscillating-rotating power brush with a new brush head with angled bristles versus a marketed sonic brush with self-adjusting technology.

    Science.gov (United States)

    Klukowska, Malgorzata; Grender, Julie M; Conde, Erinn; Ccahuana-Vasquez, Renzo Alberto; Ram Goyal, C

    2014-08-01

    To compare the efficacy of an oscillating-rotating power toothbrush with a novel brush head incorporating angled CrissCross bristles (Oral-B Pro 7000 SmartSeries and Oral-B CrossAction brush head) versus a marketed sonic toothbrush (Colgate ProClinical A1500 with the Triple Clean brush head) in the reduction of gingivitis and plaque over a 6-week period. This was a single center, randomized, open label, examiner-blind, 2-treatment, parallel group study. Study participants who met the entrance criteria were enrolled in the study and randomly assigned to one of the two toothbrush groups. Study participants brushed with their assigned toothbrush and a marketed fluoride dentifrice for 2 minutes twice daily at home for 6 weeks. Gingivitis and plaque were evaluated at baseline and Week 6. Gingivitis was assessed using the Modified Gingival Index (MGI) and Gingival Bleeding Index (GBI) and plaque was assessed using the Rustogi Modified Navy Plaque Index (RMNPI). Data was analyzed using the ANCOVA with baseline as the covariate. In total, 130 study participants were randomized to treatment resulting in 64 study participants per group completing the study. Both brushes produced statistically significant (P gingivitis and plaque measures relative to baseline. The oscillating-rotating,brush with the novel brush head demonstrated statistically significantly (P gingivitis measures, as well as whole mouth and interproximal plaque measures, compared to the sonic toothbrush. The benefit for the oscillating- rotating brush over the sonic brush was 21.3% for gingivitis, 35.7% for gingival bleeding, 34.7% for number of bleeding sites, 17.4% for whole mouth plaque, and 21.2% for interproximal plaque. There were no adverse events reported or observed for either brush.

  9. Genetic diversity of the Plasmodium falciparum apical membrane antigen I gene in parasite population from the China-Myanmar border area.

    Science.gov (United States)

    Zhu, Xiaotong; Zhao, Zhenjun; Feng, Yonghui; Li, Peipei; Liu, Fei; Liu, Jun; Yang, Zhaoqing; Yan, Guiyun; Fan, Qi; Cao, Yaming; Cui, Liwang

    2016-04-01

    To investigate the genetic diversity of the Plasmodium falciparum apical membrane antigen 1 (PfAMA1) gene in Southeast Asia, we determined PfAMA1 sequences from 135 field isolates collected from the China-Myanmar border area and compared them with 956 publically available PfAMA1 sequences from seven global P. falciparum populations. This analysis revealed high genetic diversity of PfAMA1 in global P. falciparum populations with a total of 229 haplotypes identified. The genetic diversity of PfAMA1 gene from the China-Myanmar border is not evenly distributed in the different domains of this gene. Sequence diversity in PfAMA1 from the China-Myanmar border is lower than that observed in Thai, African and Oceanian populations, but higher than that in the South American population. This appeared to correlate well with the levels of endemicity of different malaria-endemic regions, where hyperendemic regions favor genetic cross of the parasite isolates and generation of higher genetic diversity. Neutrality tests show significant departure from neutrality in the entire ectodomain and Domain I of PfAMA1 in the China-Myanmar border parasite population. We found evidence supporting a substantial continent-wise genetic structure among P. falciparum populations, with the highest genetic differentiation detected between the China-Myanmar border and the South American populations. Whereas no alleles were unique to a specific region, there were considerable geographical differences in major alleles and their frequencies, highlighting further necessity to include more PfAMA1 alleles in vaccine designs. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Nanopatterned polymer brushes: conformation, fabrication and applications

    Science.gov (United States)

    Yu, Qian; Ista, Linnea K.; Gu, Renpeng; Zauscher, Stefan; López, Gabriel P.

    2015-12-01

    Surfaces with end-grafted, nanopatterned polymer brushes that exhibit well-defined feature dimensions and controlled chemical and physical properties provide versatile platforms not only for investigation of nanoscale phenomena at biointerfaces, but also for the development of advanced devices relevant to biotechnology and electronics applications. In this review, we first give a brief introduction of scaling behavior of nanopatterned polymer brushes and then summarize recent progress in fabrication and application of nanopatterned polymer brushes. Specifically, we highlight applications of nanopatterned stimuli-responsive polymer brushes in the areas of biomedicine and biotechnology.

  11. Phosphorous digestibility and activity of intestinal phytase in hybrid tilapia, Oreochromis niloticus X O. aureus

    Science.gov (United States)

    La Vorgna, M.W.; Hafez, Y.; Hughes, S.G.; Handwerker, T.

    2003-01-01

    Experiments were conducted to determine the degree to which phytate-bound phosphorus from plant protein sources could be used by hybrid tilapia (Oreochromis niloticus X O. aureus). Utilizing an inert marker technique with chromic oxide, hybrid tilapia in our study were effective at utilizing both inorganic and phytate phosphorus as evidenced by average apparent digestibility values of 93.2% and 90.0% for total and phytate phosphorus, respectively. Analysis of the intestinal brush border membrane of the tilapia revealed enzyme activity that was capable of hydrolyzing phytic acid. The presence of phytic acid hydrolyzing enzyme activity in the intestinal brush border provides a probable mechanism by which these hybrid tilapia are able to utilize phytate phosphorus effectively. ?? 2003 by The Haworth Press, Inc. All rights reserved.

  12. Nonlinearity in the rotational dynamics of Haidinger's brushes

    Science.gov (United States)

    Rothmayer, Mark; Dultz, Wolfgang; Frins, Erna; Zhan, Qiwen; Tierney, Dennis; Schmitzer, Heidrun

    2007-10-01

    Haidinger's brushes are an entoptic effect of the human visual system that enables us to detect polarized light. However, individual perceptions of Haidinger's brushes can vary significantly. We find that the birefringence of the cornea influences the rotational motion and the contrast of Haidinger's brushes and may offer an explanation for individual differences. We have devised an experimental setup to simulate various phase shifts of the cornea and found a switching effect in the rotational dynamics of Haidinger's brushes. In addition, age related macular degeneration reduces the polarization effect of the macula and thus also leads to changes in the brush pattern.

  13. Comparative analysis of Bacillus thuringiensis toxin binding to gypsy moth, browntail moth, and douglas-fir tussock moth midgut tissue sections using fluorescence microscopy

    Science.gov (United States)

    Algimantas P. Valaitis; John D. Podgwaite

    2011-01-01

    Many strains of Bacillus thuringiensis (Bt) produce insecticidal proteins, also referred to as Cry toxins, in crystal inclusions during sporulation. When ingested by insects, the Cry toxins bind to receptors on the brush border midgut epithelial cells and create pores in the epithelial gut membranes resulting in the death of...

  14. Polyelectrolyte brushes at the air/water interface

    International Nuclear Information System (INIS)

    Matsuoka, Hideki

    2005-01-01

    The nanostructure of amphiphilic diblock copolymer monolayer on water surface was investigated by in situ X-ray and neutron reflectivity. The diblock copolymers used have a long hydrophobic chain and a polyelectrolyte chain as a hydrophilic block. The monolayer was found not to have a simple double layer structure (hydrophobic layer / hydrophilic (carpet) layer) but to have a three layer structure consisting of hydrophobic layer, hydrophilic dense carpet layer, and polyelectrolyte brush layer when the polyelectrolyte block is long enough and the surface pressure (i.e. brush density) is high enough. The transition from carpet only to carpet/brush double layer structure in hydrophilic layer was observed as a function of polyelectrolyte chain length, the surface pressure. When the hydrophilic chain is a weak polyelectrolyte, the monolayer first expanded and then shrunk with increasing salt concentration in the subphase. For the strongly ionic polyelectrolyte, the monolayer structure was not affected by salt addition up to ∼0.2 M. These observations can be explained by a balance of the charged state of the brush chain, an electrostatic repulsion between brush chains and salt concentration in the brush layer

  15. Interfacial Friction and Adhesion of Polymer Brushes

    KAUST Repository

    Landherr, Lucas J. T.

    2011-08-02

    A bead-probe lateral force microscopy (LFM) technique is used to characterize the interfacial friction and adhesion properties of polymer brushes. Our measurements attempt to relate the physical structure and chemical characteristics of the brush to their properties as thin-film, tethered lubricants. Brushes are synthesized at several chain lengths and surface coverages from polymer chains of polydimethylsiloxane (PDMS), polystyrene (PS), and a poly(propylene glycol)-poly(ethylene glycol) block copolymer (PPG/PEG). At high surface coverage, PDMS brushes manifest friction coefficients (COFs) that are among the lowest recorded for a dry lubricant film (μ ≈ 0.0024) and close to 1 order of magnitude lower than the COF of a bare silicon surface. Brushes synthesized from higher molar mass chains exhibit higher friction forces than those created using lower molar mass polymers. Increased grafting density of chains in the brush significantly reduces the COF by creating a uniform surface of stretched chains with a decreased surface viscosity. Brushes with lower surface tension and interfacial shear stresses manifest the lowest COF. In particular, PDMS chains exhibit COFs lower than PS by a factor of 3.7 and lower than PPG/PEG by a factor of 4.7. A scaling analysis conducted on the surface coverage (δ) in relation to the fraction (ε) of the friction force developing from adhesion predicts a universal relation ε ∼ δ4/3, which is supported by our experimental data. © 2011 American Chemical Society.

  16. Regulation of the epithelial Ca2+ channels in small intestine as studied by quantitative mRNA detection.

    NARCIS (Netherlands)

    Abel, M. van; Hoenderop, J.G.J.; Kemp, J.W.C.M. van der; Leeuwen, J.P.P.M. van; Bindels, R.J.M.

    2003-01-01

    The epithelial Ca2+ channels TRPV5 and TRPV6 are localized to the brush border membrane of intestinal cells and constitute the postulated rate-limiting entry step of active Ca2+ absorption. The aim of the present study was to investigate the hormonal regulation of these channels. To this end, the

  17. Water driven turbine/brush pipe cleaner

    Science.gov (United States)

    Werlink, Rudy J. (Inventor)

    1995-01-01

    Assemblies are disclosed for cleaning the inside walls of pipes and tubes. A first embodiment includes a small turbine with angled blades axially mounted on one end of a standoff support. An O-ring for stabilizing the assembly within the pipe is mounted in a groove within the outer ring. A replaceable circular brush is fixedly mounted on the opposite end of the standoff support and can be used for cleaning tubes and pipes of various diameters, lengths and configurations. The turbine, standoff support, and brush spin in unison relative to a hub bearing that is fixedly attached to a wire upstream of the assembly. The nonrotating wire is for retaining the assembly in tension and enabling return of the assembly to the pipe entrance. The assembly is initially placed in the pipe or tube to be cleaned. A pressurized water or solution source is provided at a required flow-rate to propel the assembly through the pipe or tube. The upstream water pressure propels and spins the turbine, standoff support and brush. The rotating brush combined with the solution cleans the inside of the pipe. The solution flows out of the other end of the pipe with the brush rotation controlled by the flow-rate. A second embodiment is similar to the first embodiment but instead includes a circular shaped brush with ring backing mounted in the groove of the exterior ring of the turbine, and also reduces the size of the standoff support or eliminates the standoff support.

  18. Dual wound dc brush motor gearhead

    Science.gov (United States)

    Henson, Barrie W.

    1986-01-01

    The design requirements, the design, development tests and problems, the qualification and life test and the findings of the strip examination of a dual wound DC brushed motor gearhead are described. It is the only space qualified dual wound dc brushed motor gearhead in Europe.

  19. Binary Polymer Brushes of Strongly Immiscible Polymers.

    Science.gov (United States)

    Chu, Elza; Babar, Tashnia; Bruist, Michael F; Sidorenko, Alexander

    2015-06-17

    The phenomenon of microphase separation is an example of self-assembly in soft matter and has been observed in block copolymers (BCPs) and similar materials (i.e., supramolecular assemblies (SMAs) and homo/block copolymer blends (HBCs)). In this study, we use microphase separation to construct responsive polymer brushes that collapse to generate periodic surfaces. This is achieved by a chemical reaction between the minor block (10%, poly(4-vinylpyridine)) of the block copolymer and a substrate. The major block of polystyrene (PS) forms mosaic-like arrays of grafted patches that are 10-20 nm in size. Depending on the nature of the assembly (SMA, HBC, or neat BCP) and annealing method (exposure to vapors of different solvents or heating above the glass transition temperature), a range of "mosaic" brushes with different parameters can be obtained. Successive grafting of a secondary polymer (polyacrylamide, PAAm) results in the fabrication of binary polymer brushes (BPBs). Upon being exposed to specific selective solvents, BPBs may adopt different conformations. The surface tension and adhesion of the binary brush are governed by the polymer occupying the top stratum. The "mosaic" brush approach allows for a combination of strongly immiscible polymers in one brush. This facilitates substantial contrast in the surface properties upon switching, previously only possible for substrates composed of predetermined nanostructures. We also demonstrate a possible application of such PS/PAAm brushes in a tunable bioadhesion-bioadhesive (PS on top) or nonbioadhesive (PAAm on top) surface as revealed by Escherichia coli bacterial seeding.

  20. Brush seal performance measurement system

    OpenAIRE

    Aksoy, Serdar; Akşit, Mahmut Faruk; Aksit, Mahmut Faruk; Duran, Ertuğrul Tolga; Duran, Ertugrul Tolga

    2009-01-01

    Brush seals are rapidly replacing conventional labyrinth seals in turbomachinery applications. Upon pressure application, seal stiffness increases drastically due to frictional bristle interlocking. Operating stiffness is critical to determine seal wear life. Typically, seal stiffness is measured by pressing a curved shoe to brush bore. The static-unpressurized measurement is extrapolated to pressurized and high speed operating conditions. This work presents a seal stiffness measurement syste...

  1. Localization and biosynthesis of aminopeptidase N in pig fetal small intestine

    DEFF Research Database (Denmark)

    Danielsen, E M; Niels-Christiansen, L L; Hansen, Gert Helge

    1995-01-01

    BACKGROUND & AIMS: Little is known about the expression of brush border enzymes in fetal enterocytes. The aim of this study was to describe the localization and biosynthesis of porcine fetal aminopeptidase N. METHODS: This study was performed using histochemistry and immunoelectron microscopy......, and large vacuoles in the apical cytoplasm. The transient high mannose-glycosylated form of fetal aminopeptidase N was processed to the mature complex-glycosylated form at a markedly slower rate than the enzyme in adult intestine. Likewise, dimerization occurred slowly compared with the adult form...... of aminopeptidase N, and it took place mainly after the Golgi-associated complex glycosylation. The enzyme had a biphasic appearance in the Mg(2+)-precipitated and microvillar fractions, indicating that the bulk of newly made aminopeptidase N is transported to the brush border membrane before appearing...

  2. Evaluation of ¹¹¹in-labelled exendin-4 derivatives containing different meprin β-specific cleavable linkers.

    Directory of Open Access Journals (Sweden)

    Andreas Jodal

    Full Text Available Cleavable linkers, which are specifically cleaved by defined conditions or enzymes, are powerful tools that can be used for various purposes. Amongst other things, they have been successfully used to deliver toxic payloads as prodrugs into target tissues. In this work novel linker sequences targeting meprin β, a metalloprotease expressed in the kidney brush-border membrane, were designed and included in the sequence of three radiolabelled exendin-4 derivatives. As radiolabelled exendin-4 derivatives strongly accumulate in the kidneys, we hypothesised that specific cleavage of the radiolabelled moiety at the kidney brush-border membrane would allow easier excretion of the activity into the urine and therefore improve the pharmacological properties of the peptide.The insertion of a cleavable linker did not negatively influence the in vitro properties of the peptides. They showed a good affinity to the GLP-1 receptor expressed in CHL cells, a high internalisation and sufficiently high stability in fresh human blood plasma. In vitro digestion with recombinant meprin β rapidly metabolised the corresponding linker sequences. After 60 min the majority of the corresponding peptides were digested and at the same time the anticipated fragments were formed. The peptides were also quickly metabolised in CD1 nu/nu mouse kidney homogenates. Immunofluorescence staining of meprin β in kidney sections confirmed the expression of the protease in the kidney brush-border membrane. Biodistribution in GLP-1 receptor positive tumour-xenograft bearing mice revealed high specific uptake of the 111In-labelled tracers in receptor positive tissue. Accumulation in the kidneys, however, was still high and comparable to the lead compound 111In-Ex4NOD40.In conclusion, we show that the concept of cleavable linkers specific for meprin β is feasible, as the peptides are rapidly cleaved by the enzyme while retaining their biological properties.

  3. Magnetohydrodynamic instability of a cylindrical liquid-metal brush

    International Nuclear Information System (INIS)

    Hong, S.H.; Wilhelm, H.E.

    1976-01-01

    The stability of a homopolar generator brush, consisting of a liquid-metal-filled cavity between rotating (rotor) and fixed (stator) cylinder electrodes, is analyzed in the presence of radial current transport and an axial homogeneous magnetic field. Within the frame of linear magnetohydrodynamics, it is shown that the liquid-metal flow in the brush is always unstable if the brush transports current. In the absence of current flow (infinite load) the axial magnetic field stabilizes the liquid-metal flow in the brush if the magnetic energy density is larger than a certain fraction of the energy density of the rotating fluid

  4. Tracking the fate of pasta (T. Durum semolina) immunogenic proteins by in vitro simulated digestion.

    Science.gov (United States)

    Mamone, Gianfranco; Nitride, Chiara; Picariello, Gianluca; Addeo, Francesco; Ferranti, Pasquale; Mackie, Alan

    2015-03-18

    The aim of the present study was to identify and characterize the celiacogenic/immunogenic proteins and peptides released during digestion of pasta (Triticum durum semolina). Cooked pasta was digested using a harmonized in vitro static model of oral-gastro-duodenal digestion. The course of pasta protein digestion was monitored by SDS-PAGE, and gluten proteins were specifically analyzed by Western blot using sera of celiac patients. Among the allergens, nonspecific lipid-transfer protein was highly resistant to gastro-duodenal hydrolysis, while other digestion-stable allergens such as α-amylase/trypsin inhibitors were not detected being totally released in the pasta cooking water. To simulate the final stage of intestinal degradation, the gastro-duodenal digesta were incubated with porcine jejunal brush-border membrane hydrolases. Sixty-one peptides surviving the brush-border membrane peptidases were identified by liquid chromatography-mass spectrometry, including several gluten-derived sequences encrypting different motifs responsible for the induction of celiac disease. These results provide new insights into the persistence of wheat-derived peptides during digestion of cooked pasta samples.

  5. Contaminated tooth brushes-potential threat to oral and general health

    Directory of Open Access Journals (Sweden)

    Rashmi Naik

    2015-01-01

    Full Text Available Background: Tooth brushing is most common method of maintaining oral hygiene. In removing plaque and other soft debris from the teeth, tooth brushes become contaminated with bacteria, blood, saliva and oral debris. These contaminated tooth brushes can be a source of infection. Aims and objectives: The aim of the present study was to evaluate the presence of microorganisms in the tooth brushes and to investigate the effect of disinfectants such as chlorhexidine gluconate, sodium hypochlorite and water to decontaminate them. Materials and Methods: Twenty-one children were asked to brush their teeth for 5 days with a tooth brush. The tooth brushes were put in Robertson′s Cooked Meat broth and were observed for growth of Streptococcal microorganisms. These tooth brushes were then placed in disinfectants such as 0.2% chlorhexidine gluconate (Group I, 1% sodium hypochlorite (Group II and water (Group III for 24 hrs and then cultured again. Reduction of growth of microorganisms was seen in Group I, Group II and remnants of growth seen in Group III. Conclusion: We conclude that the use of disinfectant for a tooth brush is a must for every individual at least at regular intervals.

  6. Superhydrophilic Polyelectrolyte Brush Layers with Imparted Anti-Icing Properties

    DEFF Research Database (Denmark)

    Chernyy, Sergey; Järn, Mikael; Shimizu, Kyoko

    2014-01-01

    . In general, superhydrophilic polyelectrolyte brushes exhibit better anti-icing property at -10 °C compared to partially hydrophobic brushes such as poly(methyl methacrylate) and surfactant exchanged polyelectrolyte brushes. The data are interpreted using the concept of a quasi liquid layer (QLL...

  7. Virtual hairy brush for digital painting and calligraphy

    Institute of Scientific and Technical Information of China (English)

    XU Songhua; Lau Francis C. M.; XU Congfu; PAN Yunhe

    2005-01-01

    The design of user friendly and expressive virtual brush systems for interactive digital painting and calligraphy has attracted a lot of attention and effort in both computer graphics and human-computer interaction circles for a long time. Providing a digital environment for paper-less artwork creation is not only challenging in terms of algorithmic design, but also promising for its potential market values. This paper proposes a novel algorithmic framework for interactive digital painting and calligraphy based a novel virtual hairy brush model. The algorithms in the kernel of our simulation framework are built upon solid modeling techniques. Implementing the algorithms, we have developed a virtual hairy brush prototype system with which end users can interactively produce high-quality digital paintings and calligraphic artwork. (The latest progress of our virtual brush project is reported at the website "http://www.cs.hku.hk/~songhua/e-brush/".)

  8. Method for making a high current fiber brush collector

    Science.gov (United States)

    Scuro, S. J.

    1986-05-01

    An axial-type homopolar motor having high density, high current fiber brush collectors affording efficient, low contact resistance and low operating temperatures is discussed. The collectors include a ring of concentric row of brushes in equally spaced beveled holes soldered in place using a fixture for heating the ring to just below the solder melting point at a soldering iron for the local application of additional heat at each brush. Prior to soldering, an oxide film is formed on the surfaces of the brushes and ring, and the bevels are burnished to form a wetting surface. Flux applied with the solder at each bevel removes to an effective soldering depth the oxide film on the brushes and the holes.

  9. Cold plasma brush generated at atmospheric pressure

    International Nuclear Information System (INIS)

    Duan Yixiang; Huang, C.; Yu, Q. S.

    2007-01-01

    A cold plasma brush is generated at atmospheric pressure with low power consumption in the level of several watts (as low as 4 W) up to tens of watts (up to 45 W). The plasma can be ignited and sustained in both continuous and pulsed modes with different plasma gases such as argon or helium, but argon was selected as a primary gas for use in this work. The brush-shaped plasma is formed and extended outside of the discharge chamber with typical dimension of 10-15 mm in width and less than 1.0 mm in thickness, which are adjustable by changing the discharge chamber design and operating conditions. The brush-shaped plasma provides some unique features and distinct nonequilibrium plasma characteristics. Temperature measurements using a thermocouple thermometer showed that the gas phase temperatures of the plasma brush are close to room temperature (as low as 42 deg. C) when running with a relatively high gas flow rate of about 3500 ml/min. For an argon plasma brush, the operating voltage from less than 500 V to about 2500 V was tested, with an argon gas flow rate varied from less than 1000 to 3500 ml/min. The cold plasma brush can most efficiently use the discharge power as well as the plasma gas for material and surface treatment. The very low power consumption of such an atmospheric argon plasma brush provides many unique advantages in practical applications including battery-powered operation and use in large-scale applications. Several polymer film samples were tested for surface treatment with the newly developed device, and successful changes of the wettability property from hydrophobic to hydrophilic were achieved within a few seconds

  10. Polyelectrolyte brushes: a novel stable lubrication system in aqueous conditions.

    Science.gov (United States)

    Kobayashi, Motoyasu; Terada, Masami; Takahara, Atsushi

    2012-01-01

    Surface-initiated controlled radical copolymerizations of 2-dimethylaminoethyl methacrylate (DMAEMA), 2-(methacryloyloxy)ethyl phosphorylcholine (MPC), 2-(methacryloyloxy)ethyltrimethylammonium chloride) (MTAC), and 3-sulfopropyl methacrylate potassium salt (SPMK) were carried out on a silicon wafer and glass ball to prepare polyelectrolyte brushes with excellent water wettability. The frictional coefficient of the polymer brushes was recorded on a ball-on-plate type tribometer by linear reciprocating motion of the brush specimen at a selected velocity of 1.5 x 10(-3) m s-1 under a normal load of 0.49 N applied to the stationary glass ball (d = 10 mm) at 298 K. The poly(DMAEMA-co-MPC) brush partially cross-linked by bis(2-iodoethoxy)ethane maintained a relatively low friction coefficient around 0.13 under humid air (RH > 75%) even after 200 friction cycles. The poly(SPMK) brush revealed an extremely low friction coefficient around 0.01 even after 450 friction cycles. We supposed that the abrasion of the brush was prevented owing to the good affinity of the poly(SPMK) brush for water forming a water lubrication layer, and electrostatic repulsive interactions among the brushes bearing sulfonic acid groups. Furthermore, the poly(SPMK-co-MTAC) brush with a chemically cross-linked structure showed a stable low friction coefficient in water even after 1400 friction cycles under a normal load of 139 MPa, indicating that the cross-linking structure improved the wear resistance of the brush layer.

  11. Evaluation of multi-brush anode systems in microbial fuel cells

    KAUST Repository

    Lanas, Vanessa

    2013-11-01

    The packing density of anodes in microbial fuel cells (MFCs) was examined here using four different graphite fiber brush anode configurations. The impact of anodes on performance was studied in terms of carbon fiber length (brush diameter), the number of brushes connected in parallel, and the wire current collector gage. MFCs with different numbers of brushes (one, three or six) set perpendicular to the cathode all produced similar power densities (1200±40mW/m2) and coulombic efficiencies (60%±5%). Reducing the number of brushes by either disconnecting or removing them reduced power, demonstrating the importance of anode projected area covering the cathode, and therefore the need to match electrode projected areas to maintain high performance. Multi-brush reactors had the same COD removal as single-brush systems (90%). The use of smaller Ti wire gages did not affect power generation, which will enable the use of less metal, reducing material costs. © 2013 Elsevier Ltd.

  12. Expression of nutrient transporters in duodenum, jejunum, and ileum of Eimeria maxima-infected broiler chickens.

    Science.gov (United States)

    Fetterer, Raymond H; Miska, Katarzyna B; Jenkins, Mark C; Wong, Eric A

    2014-10-01

    The uptake of amino acids is mediated by active transporters located on the basolateral and brush border membranes of intestinal epithelial cells. The current study investigated the expression of amino acid transporters (AAT) and other genes in the intestine of chicks infected with Eimeria maxima. At 7-day postinfection (PI), tissue from each intestinal segment (duodenum, jejunum, and ileum) was taken from birds inoculated with 3 × 10(3) oocysts/bird and processed to recover RNA. Analysis of gene expression was performed using real-time reverse transcription polymerase chain reaction (qRT-PCR). Results were given as relative expression using β₂-microglobulin as an endogenous control. All the genes studied were expressed in three segments of the intestines, and expression of the genes was altered by infection with E. maxima. Even though the jejunum is considered the parasite's primary predilection site, there was no segment-related difference in expression of most of the genes studied. The antimicrobial peptide (LEAP2) was downregulated in all three segments of the intestine. The results also demonstrate that transporters associated with brush border membranes were downregulated while transporters associated with the basolateral membranes were upregulated and that E. maxima alters the expression of AAT and LEAP2 throughout the small intestine.

  13. 75 FR 13489 - Natural Bristle Paint Brushes and Brush Heads from the People's Republic of China: Final Results...

    Science.gov (United States)

    2010-03-22

    ... Brushes and Brush Heads from the People's Republic of China: Final Results of the Expedited Sunset Review... from the People's Republic of China (``PRC'') pursuant to section 751(c) of the Tariff Act of 1930, as amended (``the Act''). See Initiation of Five-year (``Sunset'') Review, 74 FR 56593 (November 2, 2009...

  14. Tooth brushing among 11- to 15-year-olds in Denmark

    DEFF Research Database (Denmark)

    Bast, L. S.; Holstein, B. E.; Nordahl, Helene

    2015-01-01

    brushing. Results: 10,607 respondents: a response rate of 88.3%. Boys of lower social class had higher odds ratio (OR) of infrequent tooth brushing than girls: 1.98 (95% confidence interval 1.62-2.41) vs 1.80 (1.53-2.24). Immigrants and descendants had higher odds compared to adolescents of Danish origin......Objective: Regular tooth brushing in adolescence predicts stable tooth brushing habits later in life. Differences in tooth brushing habits by ethnic background and socioeconomic position have been suggested. We investigated migration status and social class in relation to infrequent tooth brushing...... both separately and combined. Methods: The study population was 11-15 year-olds chosen from a clustered random sample of schools. Univariate and multivariate logistic regression analyses estimated the separate and combined effects of migration status and social class on less than twice daily tooth...

  15. Impact of electroviscosity on the hydraulic conductance of the bordered pit membrane: a theoretical investigation.

    Science.gov (United States)

    Santiago, Michael; Pagay, Vinay; Stroock, Abraham D

    2013-10-01

    In perfusion experiments, the hydraulic conductance of stem segments ( ) responds to changes in the properties of the perfusate, such as the ionic strength ( ), pH, and cationic identity. We review the experimental and theoretical work on this phenomenon. We then proceed to explore the hypothesis that electrokinetic effects in the bordered pit membrane (BPM) contribute to this response. In particular, we develop a model based on electroviscosity in which hydraulic conductance of an electrically charged porous membrane varies with the properties of the electrolyte. We use standard electrokinetic theory, coupled with measurements of electrokinetic properties of plant materials from the literature, to determine how the conductance of BPMs, and therefore , may change due to electroviscosity. We predict a nonmonotonic variation of with with a maximum reduction of 18%. We explore how this reduction depends on the characteristics of the sap and features of the BPM, such as pore size, density of chargeable sites, and their dissociation constant. Our predictions are consistent with changes in observed for physiological values of sap and pH. We conclude that electroviscosity is likely responsible, at least partially, for the electrolyte dependence of conductance through pits and that electroviscosity may be strong enough to play an important role in other transport processes in xylem. We conclude by proposing experiments to differentiate the impact of electroviscosity on from that of other proposed mechanisms.

  16. At the border: the plasma membrane-cell wall continuum.

    Science.gov (United States)

    Liu, Zengyu; Persson, Staffan; Sánchez-Rodríguez, Clara

    2015-03-01

    Plant cells rely on their cell walls for directed growth and environmental adaptation. Synthesis and remodelling of the cell walls are membrane-related processes. During cell growth and exposure to external stimuli, there is a constant exchange of lipids, proteins, and other cell wall components between the cytosol and the plasma membrane/apoplast. This exchange of material and the localization of cell wall proteins at certain spots in the plasma membrane seem to rely on a particular membrane composition. In addition, sensors at the plasma membrane detect changes in the cell wall architecture, and activate cytoplasmic signalling schemes and ultimately cell wall remodelling. The apoplastic polysaccharide matrix is, on the other hand, crucial for preventing proteins diffusing uncontrollably in the membrane. Therefore, the cell wall-plasma membrane link is essential for plant development and responses to external stimuli. This review focuses on the relationship between the cell wall and plasma membrane, and its importance for plant tissue organization. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  17. Clinical evaluation of a newly designed orthodontic tooth brush - A clinical study

    Directory of Open Access Journals (Sweden)

    C S Saimbi

    2009-01-01

    In this study, the newly designed orthodontic tooth brush is compared with an ordinary tooth brush. Results of this study show that the newly designed orthodontic tooth brush is superior in its cleaning efficiency as compared to the ordinary tooth brush. The results show that plaque removing capacity of orthodontic tooth brush is nearly 95-99%.

  18. Polyacrylic acid polymer brushes as substrates for the incorporation of anthraquinone derivatives. Unprecedented application of decorated polymer brushes on organocatalysis

    Science.gov (United States)

    Ruiz-Muelle, Ana Belén; Contreras-Cáceres, Rafael; Oña-Burgos, Pascual; Rodríguez-Dieguez, Antonio; López-Romero, Juan Manuel; Fernández, Ignacio

    2018-01-01

    The synthesis of amino-terminated anthraquinone derivatives and their incorporation onto polymer brushes for the fabrication of silicon-based nanometric functional coatings are described for the first time. The general process involves the covalent grafting of anthraquinone 1 onto two different polymer-brushes by amidation reactions. They are composed by amino- and carboxy-terminated poly(acrylic acid) chains (PAA-NH2- and PAA-COOH, respectively) tethered by one end to an underlying silicon oxide (SiO2) substrate in a polymer brush configuration. A third substrate is fabricated by UV induced hydrosilylation reaction using undecenoic acid as adsorbate on hydrogen-terminated Si(111) surfaces. One- and two-dimensional nuclear magnetic resonance (NMR), FT-IR, MS and X-ray diffraction (XRD) were used to characterize anthraquinone 1. Ellipsometric and X-ray photoelectron spectroscopy (XPS) measurements demonstrated the presence of the polymer brushes on the silicon wafers, and atomic force microscopy (AFM) was used to study its surface morphology. The covalent linkage between anthraquinone and polymer brushes was proven by XPS and confocal fluorescence microscopy. The resulting surfaces were assayed in the heterogenous organocatalytic transformation of (1H)-indole into 3-benzyl indole with moderate yields but with high recyclability.

  19. Endobiliary brush biopsy

    DEFF Research Database (Denmark)

    Adamsen, Sven; Olsen, Marianne; Jendresen, Marianne Bille

    2006-01-01

    OBJECTIVE: Obtaining cytological specimens by wire-guided endobiliary brushing at the time of endoscopic retrograde cholangiopancreatography (ERCP) is a convenient way to reach a diagnosis. Sensitivity for malignant disease is generally around 50% and specificity around 100%. The present study wa...

  20. Electroosmotic Flow in Mixed Polymer Brush-Grafted Nanochannels

    Directory of Open Access Journals (Sweden)

    Qianqian Cao

    2016-12-01

    Full Text Available Mixed polymer brush-grafted nanochannels—where two distinct species of polymers are alternately grafted on the inner surface of nanochannels—are an interesting class of nanostructured hybrid materials. By using a coarse-grained molecular dynamics simulation method, we are able to simulate the electrokinetic transport dynamics of the fluid in such nanochannels as well as the conformational behaviors of the mixed polymer brush. We find that (1 the brush adopts vertically-layered and longitudinally-separated structures due to the coupling of electroosmotic flow (EOF and applied electric field; (2 the solvent quality affects the brush conformations and the transport properties of the EOF; (3 the EOF flux non-monotonically depends on the grafting density, although the EOF velocity in the central region of the channel monotonically depends on the grafting density.

  1. Behavioral Determinants of Brushing Young Children's Teeth: Implications for Anticipatory Guidance

    Science.gov (United States)

    Huebner, Colleen E.; Riedy, Christine A.

    2010-01-01

    Purpose The purposes of this study were to identify parents' motivation, support, and barriers to twice daily tooth-brushing of infants and preschool-age children and to discover new approaches to encourage this important health behavior. Methods Qualitative interviews were conducted with 44 rural parents about tooth-brushing habits and experiences. Results Forty of 44 parents reported that they had begun to brush their child's teeth; 24 (55%) reported brushing twice a day or more. Parents who brushed twice a day, vs less often, were more likely to describe specific skills to overcome barriers; they expressed high self-efficacy and held high self-standards for brushing. Parents who brushed their children's teeth less than twice daily were more likely to: hold false beliefs about the benefits of twice daily tooth-brushing; report little normative pressure or social support for the behavior; have lower self-standards; describe more external constraints; and offer fewer ideas to overcome barriers. Conclusions The findings support an integrative framework in which barriers and support for parents' twice daily brushing of their young children's teeth are multiple and vary among individuals. Knowledge of behavioral determinants specific to individual parents could strengthen anticipatory guidance and recommendations about at-home oral hygiene of young children. PMID:20298653

  2. Efficiency of the surgical washing of hands with brush and without brush

    Directory of Open Access Journals (Sweden)

    Fresia Canales Carmona

    2013-10-01

    Full Text Available The purpose of this article is to establish the answer to a clinical question regarding the effectiveness ofpreoperative hygiene with hand washing brush or without it. This first technique has been performed on the skinto reduce transient bacteria and to inhibit the growth of resident microorganisms as a common and required actbefore any surgical procedure. Despite this measure and others such as prophylactic antibiotics, the mainoperative complication continues to be the surgical wound infection. Today, it is as prevalent as in the past withthe consequent negative effects derived from it, both for the institutions and for patients. Being controversialtoday which one is the most effective and safe surgical hand washing method for the binomial: professionalsurgical team/ patient, this study is done under the criteria of the Evidence-Based Nursing.A question was builtin PICO format (Personal, Intervention, Comparison and Outcome. After this is done, continues informationsearch in the databases GOOGLE ACADÉMICO, Pub Med, Cochrane y Base de Datos para la Investigación enEnfermería (BDIE We obtained 20 articles related to the topic of them 8, which fulfilled the set CASPe criteriato answer the clinical question, were analyzed. We conclude that washing hands with a brush is equally effectiveas without brush technique in terms of decreased of the superficial skin bacterial flora, although this technique hasadvantages over the traditional practice.

  3. Polymer Brushes: Synthesis, Characterization, Applications

    Science.gov (United States)

    Advincula, Rigoberto C.; Brittain, William J.; Caster, Kenneth C.; Rühe, Jürgen

    2004-09-01

    Materials scientists, polymer chemists, surface physicists and materials engineers will find this book a complete and detailed treatise on the field of polymer brushes, their synthesis, characterization and manifold applications. In a first section, the various synthetic pathways and different surface materials are introduced and explained, followed by a second section covering important aspects of characterization and analysis in both flat surfaces and particles. These specific surface initiated polymerization (SIP) systems such as linear polymers, homopolymers, block copolymers, and hyperbranched polymers are unique compared to previously reported systems by chemisorption or physisorption. They have found their way in both large-scale and miniature applications of polymer brushes, which is covered in the last section. Such 'hairy' surfaces offer fascinating opportunities for addressing numerous problems of both academic and, in particular, industrial interest: high-quality, functional or protective coatings, composite materials, surface engineered particles, metal-organic interfaces, biological applications, micro-patterning, colloids, nanoparticles, functional devices, and many more. It is the desire of the authors that this book will be of benefit to readers who want to "brush-up on polymers".

  4. Antifouling Properties of Fluoropolymer Brushes toward Organic Polymers

    NARCIS (Netherlands)

    Wang, Zhanhua; Zuilhof, Han

    2016-01-01

    Fluoropolymer brushes are widely used to prevent nonspecific adsorption of commercial polymeric or biological materials due to their strongly hydrophobic character. Herein, a series of fluoropolymer brushes with different compositions, thicknesses and molecular architectures was prepared via

  5. Force-displacement measurements of earlywood bordered pits using a mesomechanical tester

    Science.gov (United States)

    Samuel L. Zelinka; Keith J. Bourne; John C. Hermanson; Samuel V. Glass; Adriana Costa; Alex C. Wiedenhoeft

    2015-01-01

    The elastic properties of pit membranes are reported to have important implications in understanding air-seeding phenomena in gymnosperms, and pit aspiration plays a large role in wood technological applications such as wood drying and preservative treatment. Here we present force–displacement measurements for pit membranes of circular bordered pits, collected on a...

  6. Brushes and soap : grafted polymers and their interactions with nanocolloids

    NARCIS (Netherlands)

    Currie, E.P.K.

    2000-01-01

    Layers of polymer chains end-attached to a grafting plane at high densities, so-called brushes, are a curious state of matter. The (average) monomer density within the brush is as high as in a semi-dilute polymer solution, resulting in a high osmotic pressure in the brush. Due to the

  7. Renal transport and metabolism of nicotinic acid

    International Nuclear Information System (INIS)

    Schuette, S.; Rose, R.C.

    1986-01-01

    Renal metabolism and brush-border transport of nicotinic acid were studied in renal cortical slices and brush-border membrane vesicles exposed to a physiological concentration of vitamin (2.2-3.5 microM). Vesicle transport of [ 3 H]nicotinic acid was found to be Na+ dependent and concentrative. The presence of a Na+ gradient resulted in a fivefold increase in the rate of nicotinic acid uptake over that observed with mannitol and caused a transient nicotinic acid accumulation two- to fourfold above the equilibrium value. The effects of membrane potential, pH, and elimination of Na+-H+ exchange were also studied. Cortical slices and isolated tubules exposed to 2.2 microM [ 14 C]nicotinic acid took up vitamin and rapidly metabolized most of it to intermediates in the Preiss-Handler pathway for NAD biosynthesis; little free nicotinic acid was detectable intracellularly. The replacement of Na+ with Li+ in the bathing medium reduced total accumulation of 14 C label primarily as a result of reduced nicotinic acid uptake. Cortical tissue concentrated free nicotinic acid only when the involved metabolic pathways were saturated by levels of nicotinic acid far in excess of what occurs in vivo

  8. Biosynthesis of intestinal microvillar proteins. Dimerization of aminopeptidase N and lactase-phlorizin hydrolase

    DEFF Research Database (Denmark)

    Danielsen, E M

    1990-01-01

    of dimers of this enzyme therefore occurs prior to the Golgi-associated processing, and the slow rate of dimerization may be the rate-limiting step in the transport from the endoplasmic reticulum to the Golgi complex. For lactase-phlorizin hydrolase, the posttranslational processing includes a proteolytic......The pig intestinal brush border enzymes aminopeptidase N (EC 3.4.11.2) and lactase-phlorizin hydrolase (EC 3.2.1.23-62) are present in the microvillar membrane as homodimers. Dimethyl adipimidate was used to cross-link the two [35S]methionine-labeled brush border enzymes from cultured mucosal...... explants. For aminopeptidase N, dimerization did not begin until 5-10 min after synthesis, and maximal dimerization by cross-linking of the transient form of the enzyme required 1 h, whereas the mature form of aminopeptidase N cross-linked with unchanged efficiency from 45 min to 3 h of labeling. Formation...

  9. LM2500+ Brush Seal Case Study

    Science.gov (United States)

    Haaser, Fred G.

    2006-01-01

    The LM2500+ industrial aeroderivative gas turbine, a 25% enhanced power derivative of the LM2500 gas turbine, recently completed its development test program during the period 5/96 - 10/96. Early in the engine program a Quality Function Deployment (QFD) process was used to determine customer needs for this project.The feedback obtained from the QFD process showed without doubt that gas turbine customers now emphasize product reliability and availability at the top of their needs. One area of development on the LM2500+ was to investigate the use of a brush seal as a means to reduce undesirable turbine cooling leakages within the turbine mid frame in order to enhance part life. This presentation presents a case study on the factors that went into evaluating a brush seal during engine test, test results, and the ultimate decision not to implement the brush seal for cost and other reasons.

  10. Fundamental and Applied Studies of Polymer Membranes

    Science.gov (United States)

    Imbrogno, Joseph

    Four major areas have been studied in this research: 1) synthesizing novel monomers, e.g. chiral monomers, to produce new types of functionalized membranes for the biotechnology and pharmaceutical industries, 2) hydrophobic brush membranes for desalinating brackish water, sea water, and separating organics, 3) fundamental studies of water interactions at surfaces using sum frequency generation (SFG), and 4) discovering new surface chemistries that will control the growth and differentiation of stem cells. We have developed a novel synthesis method in order to increase the breadth of our high throughput screening library. This library was generated using maleimide chemistry to react a common methacrylate linker with a variety of different functions groups (R groups) in order to form new monomers that were grafted from the surface of PES ultrafiltration membranes. From this work, we discovered that the chirality of a membrane can affect performance when separating chiral feed streams. This effect was observed when filtering bovine serum albumin (BSA) and ovalbumin in a high salt phosphate buffered saline (PBS, 150 mM salt). The Phe grafted membranes showed a large difference in performance when filtering BSA with selectivity of 1.13 and 1.00 for (S) and (R) Phe, respectively. However, when filtering ovalbumin, the (S) and (R) modified surfaces showed selectivity of 2.06 and 2.31, respectively. The higher selectivity enantiomer switched for the two different proteins. Permeability when filtering BSA was 3.06 LMH kPa-1 and 4.31 LMH kPa -1 for (S)- and (R)- Phe, respectively, and 2.65 LMH kPa -1 and 2.10 LMH kPa-1 when filtering ovalbumin for (S)- and (R)- Phe, respectively. Additionally, these effects were no longer present when using a low salt phosphate buffer (PB, 10 mM salt). Since, to our knowledge, membrane chirality is not considered in current industrial systems, this discovery could have a large impact on the pharmaceutical and biotechnology industries. We

  11. Polyelectrolyte brushes in mixed ionic medium studied via intermolecular forces

    Science.gov (United States)

    Farina, Robert; Laugel, Nicolas; Pincus, Philip; Tirrell, Matthew

    2011-03-01

    The vast uses and applications of polyelectrolyte brushes make them an attractive field of research especially with the growing interest in responsive materials. Polymers which respond via changes in temperature, pH, and ionic strength are increasingly being used for applications in drug delivery, chemical gating, etc. When polyelectrolyte brushes are found in either nature (e.g., surfaces of cartilage and mammalian lung interiors) or commercially (e.g., skin care products, shampoo, and surfaces of medical devices) they are always surrounded by mixed ionic medium. This makes the study of these brushes in varying ionic environments extremely relevant for both current and future potential applications. The polyelectrolyte brushes in this work are diblock co-polymers of poly-styrene sulfonate (N=420) and poly-t-butyl styrene (N=20) which tethers to a hydrophobic surface allowing for a purely thermodynamic study of the polyelectrolyte chains. Intermolecular forces between two brushes are measured using the SFA. As multi-valent concentrations are increased, the brushes collapse internally and form strong adhesion between one another after contact (properties not seen in a purely mono-valent environment).

  12. Carbazole functionalized isocyanide brushes in heterojunction photovoltaic devices

    NARCIS (Netherlands)

    Lim, E.; Gao, F.; Schwartz, E.; Schwartz, E.; Cornelissen, Jeroen Johannes Lambertus Maria; Nolte, R.J.M.; Rowan, A.E.; Greenham, N.C.; Do, L.M.

    2012-01-01

    In this work, carbazole-containing polyisocyanide (PIACz) brushes were used for photovoltaic devices. A photovoltaic device was fabricated on top of the brushes by spin-coating a suitable acceptor and evaporating an Al cathode. Devices with a poly(N-vinylcarbazole) (PVK) bulk polymer were also

  13. Intestinal sugar transport

    OpenAIRE

    Drozdowski, Laurie A; Thomson, Alan BR

    2006-01-01

    Carbohydrates are an important component of the diet. The carbohydrates that we ingest range from simple monosaccharides (glucose, fructose and galactose) to disaccharides (lactose, sucrose) to complex polysaccharides. Most carbohydrates are digested by salivary and pancreatic amylases, and are further broken down into monosaccharides by enzymes in the brush border membrane (BBM) of enterocytes. For example, lactase-phloridzin hydrolase and sucrase-isomaltase are two disaccharidases involved ...

  14. Wildlife responses to brush management: a contemporary evaluation

    Science.gov (United States)

    Brush management has been widely practiced with the general intent of curtailing or reversing the proliferation of shrubs and trees in grasslands and savannas. The traditional aim of brush management has been to increase livestock forage or to improve water yield. Its potential role for restoring h...

  15. Design and Testing of High Performance Brushes.

    Science.gov (United States)

    1983-05-01

    shows an example. What ordinarily serves as a ’brush’. applitations such as homopolar motors / generators and in transmitting current across an interface...speed current collection bricating layer of silver and graphite debris. systems for homopolar electrical machines. Use The other, associated with the...performantc hornopolar by examining the origin of the power losses when electrical motors and generators, based either on superconducting or brushes

  16. 21 CFR 868.5795 - Tracheal tube cleaning brush.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Tracheal tube cleaning brush. 868.5795 Section 868.5795 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5795 Tracheal tube cleaning brush. (a...

  17. Effect of Frequency of Brushing Teeth on Plaque and Calculus Accumulation, and Gingivitis in Dogs.

    Science.gov (United States)

    Harvey, Colin; Serfilippi, Laurie; Barnvos, Donald

    2015-01-01

    The efficacy of brushing the teeth of beagle dogs in a randomized, controlled, blinded study design using a clearly-defined brushing technique was evaluated for 4 brushing frequencies: brushing daily, brushing every other day, brushing weekly and brushing every other week, compared with no brushing in a control group of dogs. All dogs were fed a standard dry kibble diet during the study. Standard plaque, calculus, and gingivitis indices were used to score the teeth. A 'clean tooth' model was used. No gingival or non-gingival lacerations or other signs of injury to oral tissues were found at the end of the 28 day trial period. Brushing more frequently had greater effectiveness in retarding accumulation of plaque and calculus, and reducing the severity of pre-existing gingivitis. Brushing daily or every other day produced statistically significant improved results compared with brushing weekly or every other week. Based on the results of this study, daily brushing is recommended.

  18. Tooth brushing, tongue cleaning and snacking behaviour of dental technology and therapist students

    Directory of Open Access Journals (Sweden)

    Clement C. Azodo

    2010-08-01

    Full Text Available Objective: To determine the tooth brushing, tongue cleaning and snacking behaviour of dental technology and therapist students. Methods: A descriptive cross-sectional study of students of Federal School of Dental Therapy and Technology Enugu, Nigeria. Self-administered questionnaire was used to obtain information on demography, frequency, duration and technique of tooth brushing and tongue cleaning as well as information on consumption of snacks. Results: A total of 242 students responded. Dental technology students made up 52.5% of the respondents and dental therapist in training made up 47.5%. Majority (63.2% of the respondents considered the strength of tooth brush when purchasing a tooth brush and 78.9% use tooth brushes with medium strength. Seven-tenth (71.9% of the respondents brush their teeth twice daily and 52.1% brush for 3–5 minutes. About one-third (30.2% brush their teeth in front of a mirror. Chewing stick was used by 51.7% of respondents in addition to the use of tooth brush. Tongue cleaning was done by 94.2% with only 9.5% using a tongue cleaner. Only 20.2% reported regular snacks consumption. Nine-tenth (90.4% of respondents were previously involved in educating others, apart from their colleagues, on tooth brushing. Conclusion: This survey revealed that most of the dental therapy and technology students had satisfactory tooth-brushing behaviour. The zeal to educate others about proper tooth brushing revealed in this study suggests that the students may be helpful in oral health promotion.

  19. Spontaneous bending of 2D molecular bottle-brush

    NARCIS (Netherlands)

    Subbotin, A; Jong, J; ten Brinke, G

    Using a scaling approach we consider a 2D comb copolymer brush under bending deformations. We show that the rectilinear brush is locally stable and can be characterized by a persistence length lambda increasing with the molecular weight of grafting side chains as lambda similar to M-3. A bending

  20. Alcohol versus brush PRK: visual outcomes and adverse effects.

    Science.gov (United States)

    Sia, Rose K; Ryan, Denise S; Stutzman, Richard D; Psolka, Maximilian; Mines, Michael J; Wagner, Melvin E; Weber, Eric D; Wroblewski, Keith J; Bower, Kraig S

    2012-08-01

    A smooth corneal surface prior to laser ablation is important in order to achieve a favorable refractive outcome. In this study, we compare PRK outcomes following two commonly used methods of epithelial debridement: Amoils epithelial scrubber (brush) versus 20% ethanol (alcohol). We reviewed records of patients who underwent wavefront-optimized PRK for myopia or myopic astigmatism between January 2008 and June 2010. Two treatment groups (brush vs. alcohol) were compared in terms of uncorrected distance visual acuity (UDVA), manifest refraction spherical equivalent (MRSE), corrected distance visual acuity (CDVA), and complications at postoperative months 1, 3, 6, and 12. One thousand five hundred ninety-three eyes of 804 patients underwent PRK during the study period: 828 brush-treated eyes and 765 alcohol-treated eyes. At 6 months postoperatively UDVA was ≥20/20 in 94.7% of brush-treated eyes versus 94.4% of alcohol-treated eyes (P = 0.907). At 1 month a higher percentage of brush-treated eyes maintained or gained one or more lines CDVA compared to alcohol-treated eyes (P = 0.007), but there were no other differences in UDVA, MRSE, or CDVA at any point postoperatively. At 1 month 75.4% of brush-treated eyes versus 70.4% of alcohol-treated eyes were free of complications (P = 0.032), and there were fewer brush-treated eyes with corneal haze (4.0% vs. 6.9%, P = 0.012) and dry eye (8.9% vs. 14.4%, P = 0.001). Although corneal haze was slightly more frequent in the alcohol group, most was trace and not significant. Although alcohol-assisted PRK had more minor complications in the early postoperative period, including corneal haze and dry eye, results for both groups beyond 1 month were comparable. Copyright © 2012 Wiley Periodicals, Inc.

  1. Shroud brushing device

    International Nuclear Information System (INIS)

    Sakamaki, Kazuo; Takabayashi, Jun-ichi.

    1996-01-01

    A roller screw is assembled at an axial center of the inside of a device main body. A nut is assembled to the axial center of the roller screw secured so as not to be rotated, and a base is integrally connected to the nut. An air cylinder is pivoted to the base by a pin, and an arm is disposed to a piston rod of the air cylinder. The top end of the arm is secured to a motor case, and a brush is rotated by an electric motor in the motor case. The device main body is suspended into the reactor pressure vessel of a BWR type reactor, and seated on the upper surface of a fuel support metal fitting. The roller screw is rotated to move vertically the arm by way of the nut and the base. The device main body is rotated to rotate the arm. The arm is extended and then the electric motor is driven to rotate the brush thereby polishing the inner surface of the shroud. (I.N.)

  2. Shroud brushing device

    Energy Technology Data Exchange (ETDEWEB)

    Sakamaki, Kazuo; Takabayashi, Jun-ichi

    1996-07-12

    A roller screw is assembled at an axial center of the inside of a device main body. A nut is assembled to the axial center of the roller screw secured so as not to be rotated, and a base is integrally connected to the nut. An air cylinder is pivoted to the base by a pin, and an arm is disposed to a piston rod of the air cylinder. The top end of the arm is secured to a motor case, and a brush is rotated by an electric motor in the motor case. The device main body is suspended into the reactor pressure vessel of a BWR type reactor, and seated on the upper surface of a fuel support metal fitting. The roller screw is rotated to move vertically the arm by way of the nut and the base. The device main body is rotated to rotate the arm. The arm is extended and then the electric motor is driven to rotate the brush thereby polishing the inner surface of the shroud. (I.N.)

  3. Daylong Effect of Tooth Brushing or Combination Tooth Brushing and Tongue Cleaning Using Antiplaque®Toothpaste on Volatile Sulphur Compound Levels

    Directory of Open Access Journals (Sweden)

    Indriasti Indah Wardhany

    2013-07-01

    Full Text Available Objective: to determine the daylong effect of Antiplaque® toothpaste active copound and the effect of tooth brushing or combination of tooth brushing and tongue cleaning on Volatile Sulphur Compounds (VSC levels. Methods: Clinical experimental double blinded microbiological and clinical examination. Subjects mainly from dental faculty student with or without a chief complain of halitosis. One hundred and twenty subjects were divided into four groups that consist of thirty samples each group. Two group are treatment subjects were divided into four groups that consist thirty samples each group. Two groups are treatment groups using Antiplaque® toothpaste and two groups are control groups using placebo toothpaste. The daylong effects of VSC levels are measured by Halimeter and organoleptic. The intraoral status were measured including periodontal status and tongue index. Result: There are a reduction of VSC levels in both treatment and control group, but the reduction only significant in group using Antiplaque® toothpaste (Wilcoxon signed rank test, p<0.05. There are a reduction of VSC levels in both treatment using Antiplaque® toothpaste, but the combination of tooth brushing and tongue cleaning reduced VSC levels significantly lower than tooth brushing treatment (Mann Whitney U test, P,0.05. Conclusion: Tooth brushing and tongue cleaning using Antiplaque® toothpaste significantly reduced VSC levels.DOI: 10.14693/jdi.v16i2.95

  4. Radiocesium movement in a gray rabbit brush community

    International Nuclear Information System (INIS)

    Klepper, B.; Rogers, L.E.; Hedlund, J.D.; Schreckhise, R.G.; Price, K.R.

    1978-01-01

    Gray rabbit brush, Chrysothamnus nauseosus (Compositae), is the dominant shrub on disturbed land surfaces on much of the Energy Research and Development Administration's Hanford Reservation in south-central Washington State. A stand of rabbit brush growing on an inactive liquid-waste-disposal crib was studied. Thirty percent of the shrubs showed low but detectable radiation levels in a field survey. The primary radionuclide was 137 Cs. The source of 137 Cs in shrubs was the gravel drain field in the crib, at least 2.4 m below the surface, which was the approximate maximum depth of penetration of rabbit brush taproots. Cesium-137 was observed in roots of certain rabbit brush plants, in the upper 1 cm of soil, and in litter beneath contaminated plants but was not detectable in soil samples taken at depths of 15, 50, 100, and 150 cm. Invertebrates associated with a contaminated shrub showed higher concentrations of 137 Cs than did wider-ranging species. Two of seven pocket mice trapped on the crib contaminated detectable amounts of 137 Cs

  5. Design optimization of a brush turbine with a cleaner/water based solution

    Science.gov (United States)

    Kim, Rhyn H.

    1995-01-01

    Recently, a turbine-brush was analyzed based on the energy conservation and the force momentum equation with an empirical relationship of the drag coefficient. An equation was derived to predict the rotational speed of the turbine-brush in terms of the blade angle, number of blades, rest of geometries of the turbine-brush and the incoming velocity. Using the observed flow conditions, drag coefficients were determined. Based on the experimental values as boundary conditions, the turbine-brush flows were numerically simulated to understand first the nature of the flows, and to extend the observed drag coefficient to a flow without holding the turbine-brush.

  6. Keep Kids' Mouths Healthy: Brush 2min2X

    Science.gov (United States)

    Make sure your kids brush for 2 minutes, twice a day. En Español facebook twitter instagram Kids’ Healthy Mouths Health Watch & Brush! Watch ... About Kids’ Teeth Teeth Helpful Resources Links Keep Kids’ Mouths Healthy Roll over or click the time ...

  7. Parallel array of nanochannels grafted with polymer-brushes-stabilized Au nanoparticles for flow-through catalysis.

    Science.gov (United States)

    Liu, Jianxi; Ma, Shuanhong; Wei, Qiangbing; Jia, Lei; Yu, Bo; Wang, Daoai; Zhou, Feng

    2013-12-07

    Smart systems on the nanometer scale for continuous flow-through reaction present fascinating advantages in heterogeneous catalysis, in which a parallel array of straight nanochannels offers a platform with high surface area for assembling and stabilizing metallic nanoparticles working as catalysts. Herein we demonstrate a method for finely modifying the nanoporous anodic aluminum oxide (AAO), and further integration of nanoreactors. By using atomic transfer radical polymerization (ATRP), polymer brushes were successfully grafted on the inner wall of the nanochannels of the AAO membrane, followed by exchanging counter ions with a precursor for nanoparticles (NPs), and used as the template for deposition of well-defined Au NPs. The membrane was used as a functional nanochannel for novel flow-through catalysis. High catalytic performance and instantaneous separation of products from the reaction system was achieved in reduction of 4-nitrophenol.

  8. Parallel array of nanochannels grafted with polymer-brushes-stabilized Au nanoparticles for flow-through catalysis

    Science.gov (United States)

    Liu, Jianxi; Ma, Shuanhong; Wei, Qiangbing; Jia, Lei; Yu, Bo; Wang, Daoai; Zhou, Feng

    2013-11-01

    Smart systems on the nanometer scale for continuous flow-through reaction present fascinating advantages in heterogeneous catalysis, in which a parallel array of straight nanochannels offers a platform with high surface area for assembling and stabilizing metallic nanoparticles working as catalysts. Herein we demonstrate a method for finely modifying the nanoporous anodic aluminum oxide (AAO), and further integration of nanoreactors. By using atomic transfer radical polymerization (ATRP), polymer brushes were successfully grafted on the inner wall of the nanochannels of the AAO membrane, followed by exchanging counter ions with a precursor for nanoparticles (NPs), and used as the template for deposition of well-defined Au NPs. The membrane was used as a functional nanochannel for novel flow-through catalysis. High catalytic performance and instantaneous separation of products from the reaction system was achieved in reduction of 4-nitrophenol.

  9. Macroion induced dehydration of weak polyelectrolyte brushes

    Science.gov (United States)

    Zheng, Zhongli; Zhu, Y. Elaine

    2014-03-01

    The interaction of macroions, including polyelectrolytes, DNAs, and proteins, with polymer and cellular surfaces is critically related to many biomolecular activities, such as protein adsorption and DNA hybridization at probe surfaces. In an experimental approach to examine the macroion electrostatic interaction with a polymer surface while minimizing the long-debated hydrophobic interaction, we study the interaction of molybdenum-based inorganic polyoxometalate (POM) nanoclusters carrying 42 negative charges as model hydrophilic macroions with surface-tethered poly-2-vinylpyridine (P2VP) brushes immersed in aqueous solutions. By AFM, QCM, and contact goniometer, we have observed the collapse of P2VP chains by adding POM macroions at a constant pH. Surprisingly, added POM macroions can cause the shift of swollen-to-collapse transition pH to a lower value, in contrast to the shift to high pH value by adding simple monovalent salts. At sufficiently high POM concentration, a stable POM-P2VP composite layer, showing little dependence on solution pH and additional salts, can be formed, suggesting a simple route to construct meso-porous polymer membranes.

  10. Single-chain-in-mean-field simulations of weak polyelectrolyte brushes

    Science.gov (United States)

    Léonforte, F.; Welling, U.; Müller, M.

    2016-12-01

    Structural properties of brushes which are composed of weak acidic and basic polyelectrolytes are studied in the framework of a particle-based approach that implicitly accounts for the solvent quality. Using a semi-grandcanonical partition function in the framework of the Single-Chain-in-Mean-Field (SCMF) algorithm, the weak polyelectrolyte is conceived as a supramolecular mixture of polymers in different dissociation states, which are explicitly treated in the partition function and sampled by the SCMF procedure. One obtains a local expression for the equilibrium acid-base reaction responsible for the regulation of the charged groups that is also incorporated to the SCMF sampling. Coupled to a simultaneous treatment of the electrostatics, the approach is shown to capture the main features of weak polyelectrolyte brushes as a function of the bulk pH in the solution, the salt concentration, and the grafting density. Results are compared to experimental and theoretical works from the literature using coarse-grained representations of poly(acrylic acid) (PAA) and poly(2-vinyl pyridine) (P2VP) polymer-based brushes. As the Born self-energy of ions can be straightforwardly included in the numerical approach, we also study its effect on the local charge regulation mechanism of the brush. We find that its effect becomes significant when the brush is dense and exposed to high salt concentrations. The numerical methodology is then applied (1) to the study of the kinetics of collapse/swelling of a P2VP brush and (2) to the ability of an applied voltage to induce collapse/swelling of a PAA brush in a pH range close to the pKa value of the polymer.

  11. Uptake of pH-Sensitive Gold Nanoparticles in Strong Polyelectrolyte Brushes

    Directory of Open Access Journals (Sweden)

    Dikran Kesal

    2016-04-01

    Full Text Available The impact of electrostatic attraction on the uptake of gold nanoparticles (AuNPs into positively charged strong poly-[2-(Methacryloyloxy ethyl] trimethylammonium chloride (PMETAC polyelectrolyte brushes was investigated. In this work, PMETAC brushes were synthesized via surface-initiated atom transfer radical polymerization (Si-ATRP. PMETAC/AuNP composite materials were prepared by incubation of the polymer brush coated samples into 3-mercaptopropionic acid-capped AuNP (5 nm in diameter suspension. The electrostatic interactions were tuned by changing the surface charge of the AuNPs through variations in pH value, while the charge of the PMETAC brush was not affected. Atomic-force microscopy (AFM, ellipsometry, UV/Vis spectroscopy, gravimetric analysis and transmission electron microscopy (TEM were employed to study the loading and penetration into the polymer brush. The results show that the number density of attached AuNPs depends on the pH value and increases with increasing pH value. There is also strong evidence that the particle assembly is dependent on the pH value of the AuNP suspension. Incubation of PMETAC brushes in AuNP suspension at pH 4 led to the formation of a surface layer on top of the brush (2D assembly due to sterical hindrance of the clustered AuNPs, while incubation in AuNP suspension at pH 8 led to deeper particle penetration into the brush (3D assembly. The straightforward control of particle uptake and assembly by tuning the charge density of the nanoparticle surface is a valuable tool for the development of materials for colorimetric sensor applications.

  12. Functional patterns obtained by nanoimprinting lithography and subsequent growth of polymer brushes

    International Nuclear Information System (INIS)

    Genua, A; AlduncIn, J A; Pomposo, J A; Grande, H; Kehagias, N; Reboud, V; Sotomayor, C; Mondragon, I; Mecerreyes, D

    2007-01-01

    In this work the growth of polymer brushes was combined with nanoimprint lithography (NIL) in order to obtain new functional nanopatterns. First, a functional thermoplastic methacrylic copolymer poly(methyl methacrylate-co-2-bromoisobutyryl-oxy-ethyl methacrylate) was synthesized. This copolymer was successfully patterned by NIL using a silicon stamp at 160 deg. C and 60 bar. Next, hydrophilic polymer brushes based on poly(3-sulfopropylmethacrylate) and hydrophobic polymer brushes based on a poly(fluorinated methacrylate) were grown on the imprinted surfaces. The surface properties of the patterned polymer were accordingly modified and, as a consequence, the water contact angle was modified from 80.3 deg. to 32.5 deg. in the case of the hydrophilic brushes and to 118.1 deg. in the case of the hydrophobic brushes. As an application we demonstrated the use of hydrophobic polymer brushes in order to modify the surface of polymeric stamps for NIL with self-demoulding properties

  13. Dendritic brushes under theta and poor solvent conditions

    Science.gov (United States)

    Gergidis, Leonidas N.; Kalogirou, Andreas; Charalambopoulos, Antonios; Vlahos, Costas

    2013-07-01

    The effects of solvent quality on the internal stratification of polymer brushes formed by dendron polymers up to third generation were studied by means of molecular dynamics simulations with Langevin thermostat. The distributions of polymer units, of the free ends, the radii of gyration, and the back folding probabilities of the dendritic spacers were studied at the macroscopic states of theta and poor solvent. For high grafting densities we observed a small decrease in the height of the brush as the solvent quality decreases. The internal stratification in theta solvent was similar to the one we found in good solvent, with two and in some cases three kinds of populations containing short dendrons with weakly extended spacers, intermediate-height dendrons, and tall dendrons with highly stretched spacers. The differences increase as the grafting density decreases and single dendron populations were evident in theta and poor solvent. In poor solvent at low grafting densities, solvent micelles, polymeric pinned lamellae, spherical and single chain collapsed micelles were observed. The scaling dependence of the height of the dendritic brush at high density brushes for both solvents was found to be in agreement with existing analytical results.

  14. Border Crossings, US-Mexico Border, 2010, NAVTEQ

    Data.gov (United States)

    U.S. Environmental Protection Agency — NAVTEQ Border Crossings for Region 9. The Border Crossing layer contains all international border crossings for all motorway crossings, as well as other important...

  15. Improved antifouling properties of polymer membranes using a ‘layer-by-layer’ mediated method

    KAUST Repository

    Chen, Lin; Thé rien-Aubin, Hé loï se; Wong, Mavis C. Y.; Hoek, Eric M. V.; Ober, Christopher K.

    2013-01-01

    Polymeric reverse osmosis membranes were modified with antifouling polymer brushes through a 'layer by layer' (LBL) mediated method. Based on pure physical electrostatic interaction, the attachment of LBL films did not alter separation performance

  16. Experience of racism and tooth brushing among pregnant Aboriginal Australians: exploring psychosocial mediators.

    Science.gov (United States)

    Ben, J; Jamieson, L M; Priest, N; Parker, E J; Roberts-Thomson, K F; Lawrence, H P; Broughton, J; Paradies, Y

    2014-09-01

    Despite burgeoning evidence regarding the pathways by which experiences of racism influence health outcomes, little attention has been paid to the relationship between racism and oral health-related behaviours in particular. We hypothesised that self-reported racism was associated with tooth brushing, and that this association was mediated by perceived stress and sense of control and moderated by social support. Data from 365 pregnant Aboriginal Australian women were used to evaluate tooth brushing behaviour, sociodemographic factors, psychosocial factors, general health, risk behaviours and racism exposure. Bivariate associations were explored and hierarchical logistic regression models estimated odds ratios (OR) and 95% confidence intervals (CI) for tooth brushing. Perceived stress and sense of control were examined as mediators of the association between self-reported racism and tooth brushing using binary mediation with bootstrapping. High levels of self-reported racism persisted as a risk indicator for tooth brushing (OR 0.51, 95%CI 0.27,0.98) after controlling for significant covariates. Perceived stress mediated the relationship between self-reported racism and tooth brushing: the direct effect of racism on tooth brushing was attenuated, and the indirect effect on tooth brushing was significant (beta coefficient -0.09; bias-corrected 95%CI -0.166,-0.028; 48.1% of effect mediated). Sense of control was insignificant as a mediator of the relationship between racism and tooth brushing. High levels of self-reported racism were associated with non-optimal tooth brushing behaviours, and perceived stress mediated this association among this sample of pregnant Aboriginal women.. Limitations and implications are discussed.

  17. In Vivo and In Vitro Binding of Vip3Aa to Spodoptera frugiperda Midgut and Characterization of Binding Sites by 125I Radiolabeling

    Science.gov (United States)

    Chakroun, Maissa

    2014-01-01

    Bacillus thuringiensis vegetative insecticidal proteins (Vip3A) have been recently introduced in important crops as a strategy to delay the emerging resistance to the existing Cry toxins. The mode of action of Vip3A proteins has been studied in Spodoptera frugiperda with the aim of characterizing their binding to the insect midgut. Immunofluorescence histological localization of Vip3Aa in the midgut of intoxicated larvae showed that Vip3Aa bound to the brush border membrane along the entire apical surface. The presence of fluorescence in the cytoplasm of epithelial cells seems to suggest internalization of Vip3Aa or a fragment of it. Successful radiolabeling and optimization of the binding protocol for the 125I-Vip3Aa to S. frugiperda brush border membrane vesicles (BBMV) allowed the determination of binding parameters of Vip3A proteins for the first time. Heterologous competition using Vip3Ad, Vip3Ae, and Vip3Af as competitor proteins showed that they share the same binding site with Vip3Aa. In contrast, when using Cry1Ab and Cry1Ac as competitors, no competitive binding was observed, which makes them appropriate candidates to be used in combination with Vip3A proteins in transgenic crops. PMID:25002420

  18. Brushes and soap : grafted polymers and their interactions with nanocolloids

    OpenAIRE

    Currie, E.P.K.

    2000-01-01

    Layers of polymer chains end-attached to a grafting plane at high densities, so-called brushes, are a curious state of matter. The (average) monomer density within the brush is as high as in a semi-dilute polymer solution, resulting in a high osmotic pressure in the brush. Due to the grafting, however, this isotropic osmotic pressure results in an anisotropic stretching of the chains normal to the surface. This degree of stretching can be quite extensive; in this thesis PEO-chains of...

  19. Current control by a homopolar machine with moving brushes

    International Nuclear Information System (INIS)

    Vogel, H.

    1978-01-01

    The equation for TNS Doublet's E-coil circuit with moving brush homopolar machine is integrated in the flux of the homopolar for a monotonically increasing current function extending beyond the current reversal into the burn period. The results show that the moving brush feature is not useful for controlling the burn

  20. The Effects of a Brushing Procedure on Stereotypical Behavior

    Science.gov (United States)

    Davis, Tonya N.; Durand, Shannon; Chan, Jeffrey M.

    2011-01-01

    In this study we analyzed the effects of a brushing protocol on stereotyped behavior of a young boy with autism. First, a functional analysis was conducted which showed that the participant's stereotypy was maintained by automatic reinforcement. Next, the Wilbarger Protocol, a brushing intervention, was implemented. An ABA design was implemented…

  1. Effects of Bristle Hardness & Duration of Manual Tooth brushing on Plaque Control

    Directory of Open Access Journals (Sweden)

    . Sunny

    2017-03-01

    Full Text Available Background: Oral health is an integral part of general health. Poor oral health can have adverse effect on general health hence a good oral health is very essential, which in turn is achieved by good oral hygiene. Even though, the concept of good oral hygiene evolved 5000 years back, it is only in the beginning of 19th century it gained more importance. (1 Dental caries and periodontal disease are the most commonly occurring diseases affecting mankind. Dental plaque is a very important factor in the causation of both the diseases. (2 Aims & Objectives: To evaluate efficacy of four different types of toothbrushes, with difference in duration of brushing along with different bristle hardness in removal of microbial plaque. Material & Methods: In a randomized controlled trial, four groups with 40 subjects used manual toothbrushes with either hard, medium, soft and ultra-soft bristles. On baseline examination, clinical parameter plaque index (Sillness & Loe, 1964 was recorded. Selected subjects were refrained from all kinds of oral hygiene measures for 24 hrs before clinical appointment. On the day of clinical appointment scores of pre and post brushing were recorded in each patient when brushing time was set for 1 minute and same procedure was repeated after a wash off period of 3 days and similar recordings were made with brushing time of 11/2minute. Primary outcome was measured with differences in the plaque index (Sillness & Loe, 1964 compared to baseline. Results: Significant reduction in mean value of plaque score was observed on comparing pre-brushing and post-brushing data in all the subjects irrespective of bristle hardness in both 1 minute and 11/2 minute groups. On increasing time duration from 1 minute to 11/2 minute intergroup comparison revealed that significant correlation exist in mean plaque score reduction in subjects using medium bristle brush, soft bristle brush, ultra-soft bristle brush. However, no significant reduction in

  2. Trends in Social Inequality in Tooth Brushing among Adolescents: 1991-2014

    DEFF Research Database (Denmark)

    Holstein, Bjørn Evald; Bast, Lotus Sofie; Brixval, Carina Sjöberg

    2015-01-01

    This study examines whether social inequality in tooth brushing frequency among adolescents changed from 1991 to 2014. The data material was seven comparable cross-sectional studies of nationally representative samples of 11- to 15-year-olds in Denmark with data about frequency of tooth brushing...... and occupation of parents. The total number of participants was 31,464, of whom 21.7% brushed their teeth less than the recommended 2 times a day. The absolute social inequality measured as prevalence difference between low and high social class increased from 7.7% in 1991 to 14.6% in 2014. The relative social...... inequality assessed by odds ratios for infrequent tooth brushing also increased from 1991 to 2014....

  3. Synergy of brushing mode and antibacterial use on in vivo biofilm formation.

    Science.gov (United States)

    Jongsma, Marije A; van de Lagemaat, Marieke; Busscher, Henk J; Geertsema-Doornbusch, Gesinda I; Atema-Smit, Jelly; van der Mei, Henny C; Ren, Yijin

    2015-12-01

    Orthodontic, multi-strand retention-wires are used as a generalized model for oral retention sites to investigate whether biofilm left-behind after powered toothbrushing in-vivo enabled better penetration of antibacterials as compared with manual brushing. 2-cm multi-strand, stainless-steel retention-wires were placed in brackets bonded bilaterally in the upper arches of 10-volunteers. Volunteers used NaF-sodium-lauryl-sulphate-containing toothpaste and antibacterial, triclosan-containing toothpaste supplemented or not with an essential-oils containing mouthrinse. Opposite sides of the dentition including the retention-wires, were brushed manually or with a powered toothbrush. Health-care-regimens were maintained for 1-week, after which wires were removed and oral biofilm was collected. When powered toothbrushing was applied, slightly less bacteria were collected than after manual brushing, regardless whether an antibacterial-regimen was used or not. Powered-toothbrushing combined with antibacterial-regimens yielded lower biofilm viability than manual brushing, indicating better antibacterial penetration into biofilm left-behind after powered brushing. Major shifts in biofilm composition, with a decrease in prevalence of both cariogenic species and periodontopathogens, were induced after powered brushing using an antibacterial-regimen. Oral biofilm left-behind after powered brushing in-vivo enabled better penetration of antibacterials than after manual brushing. Mechanical removal of oral biofilm is important for prevention of dental pathologies, but biofilm is always left-behind, such as in fissures, buccal pits, interproximal areas and gingival margins and around orthodontic appliances. Use of antibacterial toothpastes or mouthrinses can contribute to removal or killing of biofilm bacteria, but biofilm structure hampers antibacterial penetration. A synergy between brushing mode and antibacterial-regimen applied exists with clinically demonstrable effects

  4. Gingival abrasion and recession in manual and oscillating-rotating power brush users.

    Science.gov (United States)

    Rosema, N A M; Adam, R; Grender, J M; Van der Sluijs, E; Supranoto, S C; Van der Weijden, G A

    2014-11-01

    To assess gingival recession (GR) in manual and power toothbrush users and evaluate the relationship between GR and gingival abrasion scores (GA). This was an observational (cross-sectional), single-centre, examiner-blind study involving a single-brushing exercise, with 181 young adult participants: 90 manual brush users and 91 oscillating-rotating power brush users. Participants were assessed for GR and GA as primary response variables. Secondary response variables were the level of gingival inflammation, plaque score reduction and brushing duration. Pearson correlation was used to describe the relationship between number of recession sites and number of abrasions. Prebrushing (baseline) and post-brushing GA and plaque scores were assessed and differences analysed using paired tests. Two-sample t-test was used to analyse group differences; ancova was used for analyses of post-brushing changes with baseline as covariate. Overall, 97.8% of the study population had at least one site of ≥1 mm of gingival recession. For the manual group, this percentage was 98.9%, and for the power group, this percentage was 96.7% (P = 0.621). Post-brushing, the power group showed a significantly smaller GA increase than the manual group (P = 0.004); however, there was no significant correlation between number of recession sites and number of abrasions for either group (P ≥ 0.327). Little gingival recession was observed in either toothbrush user group; the observed GR levels were comparable. Lower post-brushing gingival abrasion levels were seen in the power group. There was no correlation between gingival abrasion as a result of brushing and the observed gingival recession following use of either toothbrush. © 2014 The Authors International Journal of Dental Hygiene Published by John Wiley & Sons Ltd.

  5. Plaque-left-behind after brushing: intra-oral reservoir for antibacterial toothpaste ingredients.

    Science.gov (United States)

    Otten, Marieke P T; Busscher, Henk J; Abbas, Frank; van der Mei, Henny C; van Hoogmoed, Chris G

    2012-10-01

    Plaque is never fully removed by brushing and may act as a reservoir for antibacterial ingredients, contributing to their substantive action. This study investigates the contribution of plaque-left-behind and saliva towards substantivity of three antibacterial toothpastes versus a control paste without antibacterial claims. First, volunteers brushed 2 weeks with a control or antibacterial toothpaste. Next, plaque and saliva samples were collected 6 and 12 h after brushing and bacterial concentrations and viabilities were measured. The contributions of plaque and saliva towards substantivity were determined by combining control plaques with experimental plaque or saliva samples and subsequently assessing their viabilities. Bacterial compositions in the various plaque and saliva samples were compared using denaturing gradient gel electrophoresis. The viabilities of plaques after brushing with Colgate-Total® and Crest-Pro-Health® were smaller than of control plaques and up to 12 h after brushing with Crest-Pro-Health® plaques still contained effective, residual antibacterial activity against control plaques. No effective, residual antibacterial activity could be measured in saliva samples after brushing. There was no significant difference in bacterial composition of plaque or saliva after brushing with the different toothpastes. Plaque-left-behind after mechanical cleaning contributes to the substantive action of an antibacterial toothpaste containing stannous fluoride (Crest-Pro-Health®). The absorptive capacity of plaque-left-behind after brushing is of utmost clinical importance, since plaque is predominantly left behind in places where its removal and effective killing matter most. Therewith this study demonstrates a clear and new beneficial effect of the use of antibacterial toothpastes.

  6. Evaluation of brushing cytology in the diagnosis of Helicobacter pylori gastritis

    Directory of Open Access Journals (Sweden)

    Amir Ahmad Mostaghni

    2008-02-01

    Full Text Available Background: Helicobacter pylori (HP is the cause of the most common infection in the world. It has been recognized as the major cause of peptic ulcer and an important risk factor for gastric malignancy. A variety of reliable methods are available for detecting HP during upper gastrointestinal endoscopy. Rapid urease test (RUT is the cheapest method and histology is the most expensive brush cytology is faster and cheaper than histology. Methods: The brushing cytology materials were obtained from the antrum of the stomach in 109 patients who suffered from dyspepsia and were candidates for endoscopy. The RUT and histology with hematoxylin-eosin staining were also performed on each patient separately. The infection status for each patient was established by a concordance of two test results. Results: Seventy-eight of 100 patients (78% were diagnosed as positive for Helicobacter pylori organisms using brushing cytology. The sensitivity and specificity of brushing cytology were 96% and 72% respectively. Sensitivity of brush cytology (96% was higher than RUT (77.4%, and RUT was more specific than histology (100% vs 90%. Conclusion: Gastric brushing cytology provides an accurate, inexpensive and easy technique in the rapid detection of Helicobacter pylori infection. When additional information about the severity of mucosal damage or the presence of cell atypias is not necessary, histologic examination can be omitted, and a cost effective strategy for assessing HP status might consist of taking antral biopsies, the former for RUT and performing brush cytology slide, which should be stained and examined only when the RUT result is negative.

  7. Microsecond MD Simulations of Nano-patterned Polymer Brushes on Self-Assembled Monolayers

    Science.gov (United States)

    Buie, Creighton; Qiu, Liming; Cheng, Kwan; Park, Soyeun

    2010-03-01

    Nano-patterned polymer brushes end-grafted onto self-assembled monolayers have gained increasing research interests due to their unique thermodynamic properties and their chemical and biomedical applications in colloids, biosensing and tissue engineering. So far, the interactions between the polymer brushes with the surrounding environments such as the floor and solvent at the nanometer length scale and microsecond time scale are still difficult to obtained experimentally and computationally. Using a Coarse-Grained MD approach, polymer brushes of different monomeric lengths, grafting density and hydrophobicity of the monomers grafted on self-assembled monolayers and in explicit solvent were studied. Molecular level information, such as lateral diffusion, transverse height and volume contour of the brushes, were calculated from our microsecond-MD simulations. Our results demonstrated the significance of the hydration of the polymer in controlling the conformational arrangement of the polymer brushes.

  8. The impact of Border policy effect on cross-border ethnic areas

    Science.gov (United States)

    Bie, Q. L.; Zhou, S. Y.; Li, C. S.

    2013-11-01

    Boundary effect analysis is related to border policy making in the cross-border ethnic area. The border effect literatures show that geographic boundaries have obvious impacts on economic, social and cultural relations in both sides of a nation border. Particularly in cross-border ethnic areas, each ethnic group has strong internal spatial structure relevance, and the boundary effect is more obvious. However, most of China's border areas are cross-border ethnic areas, each of border issues is unique. Under this perspective, we analyze the border effects of various boundaries can provide basis for formulating border management policies. For small scale of cross-border ethnic minority areas, how to formulate the boundary management policy is a good question to explore. This paper is demonstrated by a study of the impact of border management policies in Dehong Dai and Jingpo Autonomous Prefecture in Yunnan Province at the border area to Burma. The comparative method is used to analysis the border management policies in past 50 decades for the border area of Yunnan Province .This research aims to define trends within border policy and its influences to national security. This paper also examines Wendy Brown's liberal theory of border management policy. We found that it is not suitable for Sino-Burma border area. The conclusion is that the changes or instability of international economic and political situation has more influence to this cross-border ethnic area, and only innovative policy will be effective in cross-border ethnic area. So the border management policies should reflect the change of international context.

  9. Visualization of structural organization of ventral membranes of sheared-open resorbing osteoclasts attached to apatite pellets.

    Science.gov (United States)

    Akisaka, Toshitaka; Yoshida, Atsushi

    2015-05-01

    Osteoclasts are highly polarized cells from both morphological and functional points of view. Using quick-freeze, rotary-replication methods combined with cell-shearing, we clarified the variability of cytoplasmic surface of the polarized membranes of osteoclasts seeded on apatite. As to the organization of actin filaments and clathrin sheets, we confirmed almost the same ventral membrane specializations of osteoclasts on apatite as seen on glass plates. The organized actin filaments and membrane-associated particles supported the ruffled border membranes. Inside the actin sealing zone, membrane specializations were not always occupied with the ruffled border but also with other types of membranes. Some osteoclasts formed an actin ring but lacked the ruffled border projections. We report a unique and distinctive membrane modification of apatite-attached osteoclasts, i.e., the presence of dense aggregates of membrane-associated particles and related structures not found in the osteoclasts seeded on glass plates. Actin filament polarity in the podosomes was determined by decoration with myosin S1. The actin filament polarity within podosome appears to be oriented predominantly with its barbed ends toward the core, whereas the interconnecting F-actin appears to be mixed oriented. Two different types of clathrin plaques displayed different distributions: clathrin-dependent endocytosis was observed in the ruffled border regions, whereas flat clathrin sheets were found in the leading edge of lamellipodia and near podosomes. The clathrin sheets adhered to the apatite surface tightly on the ventral membranes overlaying the resorption lacunae. All these membrane specializations as mentioned above may indicate the functional variability of osteoclasts seeded on apatite.

  10. Evaluation of multi-brush anode systems in microbial fuel cells

    KAUST Repository

    Lanas, Vanessa; Logan, Bruce E.

    2013-01-01

    ), the number of brushes connected in parallel, and the wire current collector gage. MFCs with different numbers of brushes (one, three or six) set perpendicular to the cathode all produced similar power densities (1200±40mW/m2) and coulombic efficiencies (60

  11. Molecular Design of Antifouling Polymer Brushes Using Sequence-Specific Peptoids.

    Science.gov (United States)

    Lau, King Hang Aaron; Sileika, Tadas S; Park, Sung Hyun; Sousa, Ana Maria Leal; Burch, Patrick; Szleifer, Igal; Messersmith, Phillip B

    2015-01-07

    Material systems that can be used to flexibly and precisely define the chemical nature and molecular arrangement of a surface would be invaluable for the control of complex biointerfacial interactions. For example, progress in antifouling polymer biointerfaces that prevent non-specific protein adsorption and cell attachment, which can significantly improve the performance of an array of biomedical and industrial applications, is hampered by a lack of chemical models to identify the molecular features conferring their properties. Poly(N-substituted glycine) "peptoids" are peptidomimetic polymers that can be conveniently synthesized with specific monomer sequences and chain lengths, and are presented as a versatile platform for investigating the molecular design of antifouling polymer brushes. Zwitterionic antifouling polymer brushes have captured significant recent attention, and a targeted library of zwitterionic peptoid brushes with a different charge densities, hydration, separations between charged groups, chain lengths, and grafted chain densities, is quantitatively evaluated for their antifouling properties through a range of protein adsorption and cell attachment assays. Specific zwitterionic brush designs were found to give rise to distinct but subtle differences in properties. The results also point to the dominant roles of the grafted chain density and chain length in determining the performance of antifouling polymer brushes.

  12. Border Crossing Points, US-Mexico Border, 2015, NAVTEQ

    Data.gov (United States)

    U.S. Environmental Protection Agency — NAVTEQ Border Crossings for the United States. The Border Crossing layer contains all international border crossings for all motorway crossings, as well as other...

  13. Minimum free-energy paths for the self-organization of polymer brushes.

    Science.gov (United States)

    Gleria, Ignacio; Mocskos, Esteban; Tagliazucchi, Mario

    2017-03-22

    A methodology to calculate minimum free-energy paths based on the combination of a molecular theory and the improved string method is introduced and applied to study the self-organization of polymer brushes under poor solvent conditions. Polymer brushes in a poor solvent cannot undergo macroscopic phase separation due to the physical constraint imposed by the grafting points; therefore, they microphase separate forming aggregates. Under some conditions, the theory predicts that the homogeneous brush and the aggregates can exist as two different minima of the free energy. The theoretical methodology introduced in this work allows us to predict the minimum free-energy path connecting these two minima as well as the morphology of the system along the path. It is shown that the transition between the homogeneous brush and the aggregates may involve a free-energy barrier or be barrierless depending on the relative stability of the two morphologies and the chain length and grafting density of the polymer. In the case where a free-energy barrier exists, one of the morphologies is a metastable structure and, therefore, the properties of the brush as the quality of the solvent is cycled are expected to display hysteresis. The theory is also applied to study the adhesion/deadhesion transition between two opposing surfaces modified by identical polymer brushes and it is shown that this process may also require surpassing a free-energy barrier.

  14. Sweet brushes and dirty proteins

    NARCIS (Netherlands)

    Bosker, Wouter T. E.; Patzsch, Katja; Stuart, Martien A. Cohen; Norde, Willem

    2007-01-01

    We studied the protein repellency of dextran brushes. Dextran was grafted to a polystyrene surface in a broad range of grafting densities using polystyrene - dextran block copolymers and the Langmuir - Blodgett deposition technique. Ellipsometry measurements confirmed a successful transfer of the

  15. Na+-H+ exchange and Na+-dependent transport systems in streptozotocin diabetic rat kidneys

    International Nuclear Information System (INIS)

    El-Seifi, S.; Freiberg, J.M.; Kinsella, F.J.; Cheng, L.; Sacktor, B.

    1987-01-01

    The streptozotocin-induced diabetic rat was used to test the hypothesis that Na + -H + exchange activity in the proximal tubule luminal membrane would be increased in association with renal hypertrophy, altered glomerular hemodynamics, enhanced filtered load and tubular reabsorption of 22 Na + , and stimulated 22 Na= pump activity in the basolateral membrane, previously reported characteristics of this experimental animal model. Amiloride-sensitive H + gradient-dependent Na + uptake and Na + gradient-dependent H + flux were increased in brush-border membrane vesicles from the streptozotocin-treated animals. Na + gradient-dependent uptakes of phosphate, D-glucose, L-proline, and myoinositol were decreased in the drug-induced diabetic animals. These membrane transport alterations were not found when the streptozotocin-diabetic animals were treated with insulin

  16. 46 CFR 108.187 - Ventilation for brush type electric motors in classified spaces.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Ventilation for brush type electric motors in classified... Ventilation for brush type electric motors in classified spaces. Ventilation for brush type electric motors in... Electrical Equipment in Hazardous Locations”, except audible and visual alarms may be used if shutting down...

  17. Border effects without borders: What divides Japan's internal trade?

    OpenAIRE

    Wrona, Jens

    2015-01-01

    Over the last 20 years the trade literature repeatedly documented the trade-reducing effects of inter- and intra-national borders. Thereby, the puzzling size and persistence of observed border effects from the beginning raised doubts on the role of underlying political borders. However, when observed border effects are not caused by political trade barriers, why should their spatial dimension then inevitably coincide with the geography of present or past political borders? This paper identifi...

  18. Vision, healing brush, and fiber bundles

    Science.gov (United States)

    Georgiev, Todor

    2005-03-01

    The Healing Brush is a tool introduced for the first time in Adobe Photoshop (2002) that removes defects in images by seamless cloning (gradient domain fusion). The Healing Brush algorithms are built on a new mathematical approach that uses Fibre Bundles and Connections to model the representation of images in the visual system. Our mathematical results are derived from first principles of human vision, related to adaptation transforms of von Kries type and Retinex theory. In this paper we present the new result of Healing in arbitrary color space. In addition to supporting image repair and seamless cloning, our approach also produces the exact solution to the problem of high dynamic range compression of17 and can be applied to other image processing algorithms.

  19. A novel approach for UV-patterning with binary polymer brushes.

    Science.gov (United States)

    Li, Lifu; Nakaji-Hirabayashi, Tadashi; Kitano, Hiromi; Ohno, Kohji; Saruwatari, Yoshiyuki; Matsuoka, Kazuyoshi

    2018-01-01

    A mixed self-assembled monolayer (SAM) of an initiator (3-(2-bromo-2-isobutyryloxy)propyl triethoxysilane) for atom transfer radical polymerization (ATRP) and an agent (6-(triethoxysilyl)hexyl 2-(((methylthio)carbonothioyl)thio)-2-phenylacetate) for reversible addition-fragmentation chain transfer (RAFT) polymerization was constructed on the surface of a silicon wafer or glass plate by a silane coupling reaction. When a UV light at 254nm was irradiated at the mixed SAM through a photomask, the surface density of the bromine atom at the end of BPE in the irradiated region was drastically reduced by UV-driven scission of the BrC bond, as observed by X-ray photoelectron spectroscopy. Consequently, the surface-initiated (SI)-ATRP of 2-ethylhexyl methacrylate (EHMA) was used to easily construct the poly(EHMA) (PEHMA) brush domain. Subsequently, SI-RAFT polymerization of a zwitterionic vinyl monomer, carboxymethyl betaine (CMB), was performed. Using the sequential polymerization, the PCMB and PEHMA brush domains on the solid substrate could be very easily patterned. Patterning proteins and cells with the binary polymer brush is expected because the PCMB brush indicated strong suppression of protein adsorption and cell adhesion, and the PEHMA brush had non-polar properties. This technique is very simple and useful for regulating the shape and size of bio-fouling and anti-biofouling domains on solid surfaces. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Molecular Velcro constructed from polymer loop brushes showing enhanced adhesion force

    Science.gov (United States)

    Zhou, Tian; Han, Biao; Han, Lin; Li, Christopher; Department of Materials Science; Engineering Team; School of Biomedical Engineering, Science; Health Systems Team

    2015-03-01

    Molecular Velcro is commonly seen in biological systems as the formation of strong physical entanglement at molecular scale could induce strong adhesion, which is crucial to many biological processes. To mimic this structure, we designed, and fabricated polymer loop brushes using polymer single crystals with desired surface functionality and controlled chain folding. Compared with reported loop brushes fabricated using triblock copolymers, the present loop bushes have precise loop sizes, loop grafting density, and well controlled tethering locations on the solid surface. Atomic force microscopy-based force spectroscopy measurements using a polymer chain coated probe reveal that the adhesion force are significantly enhanced on the loop brush surface as compared with its single-strand counterpart. This study directly shows the effect of polymer brush conformation on their properties, and suggests a promising strategy for advanced polymer surface design.

  1. De novo expression of sodium-glucose cotransporter SGLT2 in Bowman’s capsule coincides with replacement of parietal epithelial cell layer with proximal tubule-like epithelium

    OpenAIRE

    Tabatabai, Niloofar M.; North, Paula E.; Regner, Kevin R.; Kumar, Suresh N.; Duris, Christine B.; Blodgett, Amy B.

    2014-01-01

    In kidney nephron, parietal epithelial cells line the Bowman’s capsule and function as a permeability barrier for the glomerular filtrate. Bowman’s capsule cells with proximal tubule epithelial morphology have been found. However, the effects of tubular metaplasia in Bowman’s capsule on kidney function remain poorly understood. Sodium-glucose cotransporter 2 (SGLT2) plays a major role in reabsorption of glucose in the kidney and is expressed on brush border membrane of epithelial cells in the...

  2. Comparison of Three types of Tooth Brushes on Plaque and Gingival Indices: A Randomized Clinical Trial.

    Science.gov (United States)

    Moeintaghavi, Amir; Sargolzaie, Naser; Rostampour, Mehrnoosh; Sarvari, Sara; Kargozar, Sanaz; Gharaei, Shideh

    2017-01-01

    To compare clinical results of three types of manual tooth brushes on plaque removal efficacy and gingivitis. This study is a single blind randomized trial with crossover design which involved 30 periodontaly healthy individuals. Professional plaque removal and oral hygiene instruction were performed for all the participants in the first step of our study followed by asking them to avoid brushing for 2 days. Thereafter plaque and gingivitis scores were measured using plaque and gingival indices (PI and GI). Then subjects were instructed to use Pulsar tooth brush for a two-week period and then, GI and PI indices were assessed again. After passing one-week period for wash out, subjects didn't brush for 2 days and indices were recorded again. The same procedure was done for CrossAction, and Butler 411 tooth brushes respectively and at the end of the study these variables were analyzed using SPSS software ver.16. Repeated measurement ANOVA test was used to compare the scores between different brushes. Finding of this study reveals that using all three types of tooth brushes resulted in significant plaque and gingivitis reduction compared to baseline levels. Pulsar tooth brush was significantly more effective in diminishing PI and GI than Butler tooth brush (p=0.044 and 0.031 respectively). According to our findings all 3 types of tooth brushes are effective in reduction of plaque and gingivitis and this reduction is significantly greater for Pulsar tooth brush compared to Butler and CrossAction tooth brushes.

  3. Effects of whitening dentifrice on yttria-stabilized tetragonal zirconia polycrystal surfaces after simulating brushing.

    Science.gov (United States)

    Pinelli, Lígia Antunes Pereira; Gimenes Olbera, Amanda Caroline; Candido, Lucas Miguel; Miotto, Larissa Natiele; Antonio, Selma Gutierrez; Fais, Laiza Maria Grassi

    2017-01-01

    The changes that occur after brushing yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) are unknown. These changes may favor the retention of microorganisms and chemisorption of water, impairing its longevity. The purpose of this in vitro study was to evaluate the effects of a whitening dentifrice on Y-TZP surfaces after simulating 10 years of brushing. Seventy-two bar-shaped specimens (20×4×1.2 mm) were divided into 4 groups: storage in distilled water (SW, control), brushing with distilled water (BW), brushing with dentifrice (BD), and brushing with whitening dentifrice (BWD). Brushing was conducted using a linear brushing machine (878400 cycles, 0.98 N, soft toothbrush). The mean roughness (Ra) was analyzed with a profilometer and the superficial topography with scanning electron microscopy (SEM) at baseline and after treatment. Crystalline phases were characterized using x-ray diffraction. Baseline and posttreatment Ra were analyzed using the 1-way ANOVA and Tukey HSD multiple comparison test; the paired t test was used for intragroup comparison (all α=.05). The Ra (μm) means (before/after treatment) were SW 0.28/0.28; BW 0.32/0.31; BD 0.28/0.36; BWD 0.30/0.20. No statistically significant difference was found for Ra at baseline (P=.108) than for posttreatment results (P<.001); the BD group had higher Ra values when compared with baseline (P=.019); the BWD group had the lowest values (P<.001). The BD surfaces showed pronounced scratches and detachment of the surface, while BWD showed smoother surfaces; similar crystallographic results among groups were observed. Brushing Y-TZP with conventional dentifrice increased roughness, while brushing with whitening dentifrice reduced roughness. Neither dentifrice changed the crystallographic phases after brushing. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  4. Unconventional ordering behavior of semi-flexible polymers in dense brushes under compression.

    Science.gov (United States)

    Milchev, Andrey; Binder, Kurt

    2014-06-07

    Using a coarse-grained bead-spring model for semi-flexible macromolecules which form a polymer brush, the structure and dynamics of the polymers were investigated, varying the chain stiffness and the grafting density. The anchoring conditions for the grafted chains were chosen such that their first bonds were oriented along the normal to the substrate plane. The compression of such a semi-flexible brush by a planar piston was observed to be a two-stage process: for a small compression the chains were shown to contract by "buckling" deformation whereas for a larger compression the chains exhibited a collective (almost uniform) bending deformation. Thus, the stiff polymer brush underwent a 2nd order phase transition of collective bond reorientation. The pressure, required to keep the stiff brush at a given degree of compression, was thereby significantly smaller than for an otherwise identical brush made of entirely flexible polymer chains! While both the brush height and the chain linear dimensions in the z-direction perpendicular to the substrate increased monotonically with an increase in the chain stiffness, the lateral (xy) chain linear dimensions exhibited a maximum at an intermediate chain stiffness. Increasing the grafting density led to a strong decrease of these lateral dimensions which is compatible with an exponential decay. Also the recovery kinetics after removal of the compressing piston were studied, and were found to follow a power-law/exponential decay with time. A simple mean-field theoretical consideration, accounting for the buckling/bending behavior of semi-flexible polymer brushes under compression was suggested.

  5. Salt dependence of compression normal forces of quenched polyelectrolyte brushes

    Science.gov (United States)

    Hernandez-Zapata, Ernesto; Tamashiro, Mario N.; Pincus, Philip A.

    2001-03-01

    We obtained mean-field expressions for the compression normal forces between two identical opposing quenched polyelectrolyte brushes in the presence of monovalent salt. The brush elasticity is modeled using the entropy of ideal Gaussian chains, while the entropy of the microions and the electrostatic contribution to the grand potential is obtained by solving the non-linear Poisson-Boltzmann equation for the system in contact with a salt reservoir. For the polyelectrolyte brush we considered both a uniformly charged slab as well as an inhomogeneous charge profile obtained using a self-consistent field theory. Using the Derjaguin approximation, we related the planar-geometry results to the realistic two-crossed cylinders experimental set up. Theoretical predictions are compared to experimental measurements(Marc Balastre's abstract, APS March 2001 Meeting.) of the salt dependence of the compression normal forces between two quenched polyelectrolyte brushes formed by the adsorption of diblock copolymers poly(tert-butyl styrene)-sodium poly(styrene sulfonate) [PtBs/NaPSS] onto an octadecyltriethoxysilane (OTE) hydrophobically modified mica, as well as onto bare mica.

  6. Nanostructure of Cationic Polymer Brush at the Air/Water Interface

    Directory of Open Access Journals (Sweden)

    Matsuoka Hideki

    2013-08-01

    Full Text Available Cationic amphiphilic diblock copolymers were synthesized by RAFT polymerization and the nanostructure of their monolayers was investigated by π-A isotherm and X-ray reflectivity. Carpet layer (dense hydrophilic block layer formation under the hydrophobic layer was confirmed and a “brush” layer was found beneath the carpet layer. However, the thickness of brush layer was much thinner than that of the fully-stretched chain length. The critical salt concentration was found to be 0.01 M NaCl, which is much lower than that of the previous strongly anionic brush. These differences were probably caused by the low effective charge on the brush chains due to the hydrophobic nature of the quarternized ammonium cation.

  7. Preparing high-density polymer brushes by mechanically assisted polymer assembly (MAPA)

    Science.gov (United States)

    Wu, Tao; Efimenko, Kirill; Genzer, Jan

    2001-03-01

    We introduce a novel method of modifying the surface properties of materials. This technique, called MAPA (="mechanically assisted polymer assembly"), is based on: 1) chemically attaching polymerization initiators to the surface of an elastomeric network that has been previously stretched by a certain length, Δx, and 2) growing end-anchored macromolecules using surface initiated ("grafting from") atom transfer living radical polymerization. After the polymerization, the strain is removed from the substrate, which returns to its original size causing the grafted macromolecules to stretch away from the substrate and form a dense polymer brush. We demonstrate the feasibility of the MAPA method by preparing high-density polymer brushes of poly(acryl amide), PAAm. We show that, as expected, the grafting density of the PAAm brushes can be increased by increasing Δx. We demonstrate that polymer brushes with extremely high grafting densities can be successfully prepared by MAPA.

  8. The Art and Science of Polymer Brushes: Recent Developments in Patterning and Characterization Approaches.

    Science.gov (United States)

    Panzarasa, Guido

    2017-06-28

    Polymer brushes are dense arrays of macromolecular chains tethered by one end at a surface. They are at the cutting edge of polymer nanotechnology since the dawn of controlled surface-initiated polymerization techniques unlocked new prospects for the synthesis of polymer brushes with tailorable properties. More recently, thanks to the growing interest in the use of brushes for the generation of functional surfaces, the need for advanced patterning and characterization approaches rapidly increased. Meeting these needs requires the contribution of experts from different disciplines: polymer chemistry, surface science, electrochemistry and particle physics. The focus of this review is to highlight recent developments in the field of polymer brushes, specifically the application of photocatalytic lithography as a versatile patterning strategy, the study of grafted-from polymer brushes by electrochemical methods and, most importantly, the introduction of positron annihilation spectroscopy as a powerful technique for the investigation of the structure of polymer brushes and of their composites with nanoparticles.

  9. A bioartificial environment for kidney epithelial cells based on a supramolecular polymer basement membrane mimic and an organotypical culture system.

    Science.gov (United States)

    Mollet, Björne B; Bogaerts, Iven L J; van Almen, Geert C; Dankers, Patricia Y W

    2017-06-01

    Renal applications in healthcare, such as renal replacement therapies and nephrotoxicity tests, could potentially benefit from bioartificial kidney membranes with fully differentiated and functional human tubular epithelial cells. A replacement of the natural environment of these cells is required to maintain and study cell functionality cell differentiation in vitro. Our approach was based on synthetic supramolecular biomaterials to mimic the natural basement membrane (BM) on which these cells grow and a bioreactor to provide the desired organotypical culture parameters. The BM mimics were constructed from ureidopyrimidinone (UPy)-functionalized polymer and bioactive peptides by electrospinning. The resultant membranes were shown to have a hierarchical fibrous BM-like structure consisting of self-assembled nanofibres within the electrospun microfibres. Human kidney-2 (HK-2) epithelial cells were cultured on the BM mimics under organotypical conditions in a custom-built bioreactor. The bioreactor facilitated in situ monitoring and functionality testing of the cultures. Cell viability and the integrity of the epithelial cell barrier were demonstrated inside the bioreactor by microscopy and transmembrane leakage of fluorescently labelled inulin, respectively. Furthermore, HK-2 cells maintained a polarized cell layer and showed modulation of both gene expression of membrane transporter proteins and metabolic activity of brush border enzymes when subjected to a continuous flow of culture medium inside the new bioreactor for 21 days. These results demonstrated that both the culture and study of renal epithelial cells was facilitated by the bioartificial in vitro environment that is formed by synthetic supramolecular BM mimics in our custom-built bioreactor. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  10. Strong Stretching of Poly(ethylene glycol) Brushes Mediated by Ionic Liquid Solvation.

    Science.gov (United States)

    Han, Mengwei; Espinosa-Marzal, Rosa M

    2017-09-07

    We have measured forces between mica surfaces coated with a poly(ethylene glycol) (PEG) brush solvated by a vacuum-dry ionic liquid, 1-ethyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)imide, with a surface forces apparatus. At high grafting density, the solvation mediated by the ionic liquid causes the brush to stretch twice as much as in water. Modeling of the steric repulsion indicates that PEG behaves as a polyelectrolyte; the hydrogen bonding between ethylene glycol and the imidazolium cation seems to effectively charge the polymer brush, which justifies the strong stretching. Importantly, under strong polymer compression, solvation layers are squeezed out at a higher rate than for the neat ionic liquid. We propose that the thermal fluctuations of the PEG chains, larger in the brush than in the mushroom configuration, maintain the fluidity of the ionic liquid under strong compression, in contrast to the solid-like squeezing-out behavior of the neat ionic liquid. This is the first experimental study of the behavior of a polymer brush solvated by an ionic liquid under nanoconfinement.

  11. Applications of functional polymer brushes for nanoparticle uptake and prevention of protein adsorption

    Science.gov (United States)

    Arifuzzaman, Shafi M.

    The central theme of this Ph.D. dissertation is to develop novel multifunctional polymer coatings for understanding partition of proteins and nanoparticles on polymers grafted to flat surfaces (so-called brushes). Systematic investigation of the adsorption phenomena is accomplished by utilizing surface-anchored assemblies comprising grafted polymers with variation in physical properties (i.e., length or/and grafting density) and chemical functionality. The chemical composition of the brush is tailored by either "chemical coloring" of a parent homopolymer brush with selective chemical moieties or by sequential growth of two chemically dissimilar polymer blocks. We present preparation of two types of tailor-made, surface-grafted copolymers: (1) those composed of hydrophilic and hydrophobic blocks (so-called amphiphilic polymer brushes), and (2) those comprising of anionic and cationic polymer segments (so-called polyampholyte brushes). We describe the organization of functionality in the grafted polymer brushes and the partitioning of proteins and nanoparticles using a battery of complementary analytical probes. Specifically, we address how varying the molecular weight, grafting density, and chemical composition of the brush affects adsorbtion and desorbtion of model proteins and gold nanoparticles. Our observations indicate densely-populated responsive amphiphilic polymers are very efficient in suppressing protein adsorption. In addition, we have established that the length of poly(ethylene glycol) spacers attached to a parent homopolymer brush is a key factor governing uptake of gold nanoparticles. Both grafting density and molecular weight of the coating are important in controlling the kinetics and thermodynamics of protein adsorption on surfaces. Our findings and methodologies can lead to the development of next generation environmentally friendly antifouling surfaces and will find application in medical devices, antifouling coatings and anti reflection finishes.

  12. Identification and characterization of insulin receptors in basolateral membranes of dog intestinal mucosa

    International Nuclear Information System (INIS)

    Gingerich, R.L.; Gilbert, W.R.; Comens, P.G.; Gavin, J.R. III

    1987-01-01

    Little is known about hormonal regulation of substrate transport and metabolism in the mucosal lining of the small intestine. Because insulin regulates these functions in other tissues by binding to its receptor, we have investigated the presence of insulin receptors in canine small intestinal mucosa with basolateral membranes (BLM) and brush border membranes (BBM) prepared by sorbitol density centrifugation. A14-[ 125 I]iodoinsulin was used to study binding and structural characteristics of specific insulin receptors in BLM. Analysis of receptors in BLM identified binding sites with high affinity (Kd 88 pM) and low capacity (0.4 pmol/mg protein) as well as with low affinity (Kd 36 nM) and high capacity (4.7 pmol/mg protein). Binding was time, temperature, and pH dependent, and 125 I-labeled insulin dissociation was enhanced in the presence of unlabeled insulin. Cross-reactivity of these receptors to proinsulin, IGF-II, and IGF-I was 4, 1.8, and less than 1%, respectively. Covalent cross-linking of labeled insulin to BLM insulin receptors with disuccinimidyl suberate revealed a single 135,000-Mr band that was completely inhibited by unlabeled insulin. There was a 16-fold greater specific binding of insulin to BLM (39.0 +/- 2.4%) than to BBM (2.5 +/- 0.6%). These results demonstrate the presence of a highly specific receptor for insulin on the vascular, but not the luminal, surface of the small intestinal mucosa in dogs, and suggest that insulin may play an important role in the regulation of gastrointestinal physiology

  13. Calves Use an Automated Brush and a Hanging Rope When Pair-Housed

    Directory of Open Access Journals (Sweden)

    Gosia Zobel

    2017-11-01

    Full Text Available Calf housing often only meets the basic needs of calves, but there is a growing interest in providing enrichments. This study described the behaviour of calves when they were given the opportunity to interact with two commonly available enrichment items. Female and male calves (approximately 11 days old were pair-housed in 8 identical pens fitted with an automated brush and a hanging rope. Frequency and duration of behaviours were recorded on 3 separate days (from 12:00 until 08:00 the following day. Calves spent equal time using the brush and rope (27.1 min/day, but there was less variation in the use of the brush as opposed to the rope (coefficient of variation, CV: 23 vs. 78%, respectively. Calves had more frequent (94 bouts, CV: 24% and shorter (17.8 s/bout, CV: 24% brush use bouts compared to fewer (38 bouts, CV: 43% and longer (38.3 s/bout, CV: 53% rope use bouts. There was a diurnal pattern of use for both items. Frequency of play was similar to rope use, but total time playing was 8% of rope and brush use. Variability among calves suggested that individual preference existed; however, the social dynamics of the pair-housed environment were not measured and therefore could have influenced brush and rope use. Multiple enrichment items should be considered when designing improvements to calf housing.

  14. Development of the Upgraded DC Brush Gear Motor for Spacebus Platforms

    Science.gov (United States)

    Berning, Robert H.; Viout, Olivier

    2010-01-01

    The obsolescence of materials and processes used in the manufacture of traditional DC brush gear motors has necessitated the development of an upgraded DC brush gear motor (UBGM). The current traditional DC brush gear motor (BGM) design was evaluated using Six-Sigma process to identify potential design and production process improvements. The development effort resulted in a qualified UBGM design which improved manufacturability and reduced production costs. Using Six-Sigma processes and incorporating lessons learned during the development process also improved motor performance for UBGM making it a more viable option for future use as a deployment mechanism in space flight applications.

  15. Hydration of poly( N-isopropylacrylamide) brushes on micro-silica beads measured by a fluorescent probe

    Science.gov (United States)

    Hattori, Yusuke; Nagase, Kenichi; Kobayashi, Jun; Kikuchi, Akihiko; Akiyama, Yoshikatsu; Kanazawa, Hideko; Okano, Teruo

    2010-05-01

    Hydration of poly( N-isopropylacrylamide) brushes on silica micro-beads was investigated using a fluorescent probe method. The free ends, the bottom, and the random of brushes were labeled with dansyl group. The emission spectra at the thin brushes were reduced with increasing temperature regardless of their labeling locations. At the free ends of thick brushes, the emission intensity was enhanced at 500 nm and reduced at 455 nm by heating, which was corresponding to the local micro-environmental change around the free ends. The spectral shift was speculated to be due to the enhancement of the flexibility and the hydration of thick brushes.

  16. Analysis of carbon fiber brush loading in anodes on startup and performance of microbial fuel cells

    KAUST Repository

    Hutchinson, Adam J.

    2011-11-01

    Flat carbon anodes placed near a cathode in a microbial fuel cell (MFC) are adversely affected by oxygen crossover, but graphite fiber brush anodes placed near the cathode produce high power densities. The impact of the brush size and electrode spacing was examined by varying the distance of the brush end from the cathode and solution conductivity in multiple MFCs. The startup time was increased from 8 ± 1 days with full brushes (all buffer concentrations) to 13 days (50 mM), 14 days (25 mM) and 21 days (8 mM) when 75% of the brush anode was removed. When MFCs were all first acclimated with a full brush, up to 65% of the brush material could be removed without appreciably altering maximum power. Electrochemical impedance spectroscopy (EIS) showed that the main source of internal resistance (IR) was diffusion resistance, which together with solution resistance reached 100 Ω. The IR using EIS compared well with that obtained using the polarization data slope method, indicating no major components of IR were missed. These results show that using full brush anodes avoids adverse effects of oxygen crossover during startup, although brushes are much larger than needed to sustain high power. © 2011 Elsevier B.V.

  17. Analysis of carbon fiber brush loading in anodes on startup and performance of microbial fuel cells

    KAUST Repository

    Hutchinson, Adam J.; Tokash, Justin C.; Logan, Bruce E.

    2011-01-01

    Flat carbon anodes placed near a cathode in a microbial fuel cell (MFC) are adversely affected by oxygen crossover, but graphite fiber brush anodes placed near the cathode produce high power densities. The impact of the brush size and electrode spacing was examined by varying the distance of the brush end from the cathode and solution conductivity in multiple MFCs. The startup time was increased from 8 ± 1 days with full brushes (all buffer concentrations) to 13 days (50 mM), 14 days (25 mM) and 21 days (8 mM) when 75% of the brush anode was removed. When MFCs were all first acclimated with a full brush, up to 65% of the brush material could be removed without appreciably altering maximum power. Electrochemical impedance spectroscopy (EIS) showed that the main source of internal resistance (IR) was diffusion resistance, which together with solution resistance reached 100 Ω. The IR using EIS compared well with that obtained using the polarization data slope method, indicating no major components of IR were missed. These results show that using full brush anodes avoids adverse effects of oxygen crossover during startup, although brushes are much larger than needed to sustain high power. © 2011 Elsevier B.V.

  18. The use of non-bronchoscopic brushings to study the paediatric airway

    Directory of Open Access Journals (Sweden)

    Kicic Anthony

    2005-06-01

    Full Text Available Abstract Background The use of cytology brushes for the purpose of obtaining respiratory cells from adults for clinical and research purposes is well established. However, the safety and utility of non-bronchoscopic brushings to study the paediatric airway has not been assessed. The purpose of this study was to assess the practicality of using non-bronchoscopic brushing to sample epithelial cells from children for investigation of epithelial function in health and disease using a wide range of molecular and cellular techniques. Methods Non-bronchoscopic brushing was investigated in a non-selected cohort of healthy, and mildly asthmatic children presenting for surgery unrelated to respiratory conditions, at the major children's hospital in Perth. Safety and side-effects of the procedure were assessed. Cell number, phenotype and viability were measured for all samples. The potential of these cells for use in long-term cell culture, immunohistochemistry, western blotting, quantitative PCR and gene arraying was examined. Results Non-bronchoscopic brushing was well tolerated in all children. The only significant side effect following the procedure was cough: nursing staff reported cough in 20% of patients; parents reported cough in 40% of patients. Cells sampled were of sufficient quantity and quality to allow cell culture in 93% of samples. Similarly, protein and RNA extracted from the cells was suitable for investigation of both gene and protein expression using micro-array and real-time PCR. Conclusion Non-bronchoscopic brushing in children is safe and easy to perform, and is not associated with any complications. Using this technique, adequate numbers of epithelial cells can be retrieved to allow cell culture, western blotting, real time PCR, and microarray analysis. The purpose of this study is to demonstrate the utility of non-bronchoscopic airway brushing to obtain and study epithelial cells and to encourage others so that we can accelerate

  19. Measurement of Tooth Brushing Frequency, Time of Day and Duration of Adults and Children in Jakarta, Indonesia

    Directory of Open Access Journals (Sweden)

    Anton Rahardjo

    2015-05-01

    Full Text Available Epidemiological study of tooth brushing is essential to evaluate dental health of a country. Objective: To obtain data on tooth brushing frequency, time of day and duration from adults and children in Jakarta, Indonesia. Methods: Toothbrushes containing data loggers were distributed to 120 random families in Jakarta to record how many times a day, when and for how long subjects brushed their teeth. The families were each composed of a mother, father and two children aged between 6 and 15 years. Results: The mean brushing frequency of the population was 1.27 times per day. The majority of the tooth brushing (46% was performed in the morning. The mean tooth brushing duration of this population was 57.29 seconds. The mothers’ tooth brushing frequencies tended to be higher than that of the other family members, and the fathers tended to brush their teeth longer. Conclusion: Effective education aimed at increasing both the duration and frequency of tooth brushing from once to twice per day is urgently required in Indonesia.DOI: 10.14693/jdi.v21i3.251

  20. Border markets

    DEFF Research Database (Denmark)

    Walther, Olivier

    2014-01-01

    The objective of this issue of Articulo – Journal of Urban Research is to examine the characteristics of border markets in a comparative perspective. In this introductory paper, I first discuss what makes African border markets different from other markets, and examine several factors that explain...... their unequal economic development: the presence of a trade community, the combination of trading and productive activities, and the relative porosity of borders. In a second part, I examine how border markets on the U.S.-Mexico border must simultaneously guarantee the security of the state while favoring...... regional trade. The last part of the paper argues that more policy attention should be paid to border markets which, despite being at the margin of states, are a vital component of their economy. Fifty years after most West African states became independent and just as NAFTA turns 20, it is high time...

  1. Frequency of daily tooth brushing: predictors of change in 9- to 11-year old US children.

    Science.gov (United States)

    Polk, D E; Geng, M; Levy, S; Koerber, A; Flay, B R

    2014-09-01

    To investigate whether an increase in daily tooth brushing frequency in children was predicted by either a) having a strong intention to brush twice a day or b) their parents receiving information about their new caries experience. Secondary data analyses were conducted on two waves of data from the Aban Aya Youth Project and the Iowa Fluoride Study. The Aban Aya study included 576 10- and 11-year olds from Chicago, Illinois. The Iowa Fluoride Study included a convenience sample of 709 babies born in Iowa. The present study includes those children at age 9. In both studies, reported daily tooth brushing frequency was assessed twice six months apart. In the Aban Aya data, compared with children with a weak intention at wave 1 to brush twice a day, children with a strong intention to brush twice a day were more likely to increase their brushing frequency by wave 2, OR 7.0, 95%CI 1.5,32.9. In the Iowa Fluoride Study, compared with children who did not have new caries at wave 1, children who had new caries experience were less likely to increase their brushing frequency by wave 2, OR 0.4, 95%CI 0.2,0.9. Strengthening intention to brush twice a day might increase children's brushing frequency. However, simply providing parents with information about new caries probably will not. Future studies should assess tooth brushing frequency, habit strength, intention, and situational cues at closely-spaced waves.

  2. Features of Running Brush Motors in Dry Nitrogen Environment When Using in Electrohydraulic Actuators

    Directory of Open Access Journals (Sweden)

    Y. A. Petrov

    2014-01-01

    Full Text Available The work concerns the constructive characteristics optimization of brushless D.C. (direct current motors used in electromechanical spacecraft drives.The spacecraft electromechanical drives and units use rather widely the brushless D.C. motors in which a motor commutator is replaced with more reliable semiconductor commutator controlled by the rotor position sensors. However, these motors are of low power.Electrohydraulic actuators (EHA use simple permanent-magnet motors (PMM of rather high power and commutator motors with graphite brush variable contacts.High reliability of brush motors, and, therefore a reliability of EHA in general, substantially depends on the quality of motor commutator operation. There are different reasons for a possible impact on the normal motor commutator operation. One of them is brush wear. Sparking brushes and burning commutator bars are possible in case brushes are poorly grinded to fit, brushes cannot freely move true in the brush holder box, and in case an incorrect force to clamp brushes to the commutator is chosen.It is established that drive wear resistance and operability depends on the gas environment composition being under sealed motor housing. In dry nitrogen environment brush wear suddenly raises because of the changing tribological performances of the commutator thus leading to essentially falling isolation resistance and no motor start.It is recommended to fill a space under sealed motor housing with air. Positive experience of operating spacecraft device containers with mobile electromechanical couples allowed us to find that in this case a dew point of filled air must be minus 20˚C.The paper offers an electromechanical alternative of design to the electrohydraulic actuators, with a ball-screw gear of the actuation mechanism, possessing a number of advantages.

  3. Metastatic urachal carcinoma in bronchial brush cytology

    Directory of Open Access Journals (Sweden)

    Fatima Zahra Aly

    2013-01-01

    Full Text Available Urachal carcinoma is rare comprising less than 1% of all bladder carcinomas. Metastases of urachal carcinoma have been reported to meninges, brain, ovary, lung, and maxilla. Cytologic features of metastatic urachal carcinoma have not been previously reported. We present a case of metastatic urachal adenocarcinoma in bronchial brushings and review the use of immunohistochemistry in its diagnosis. A 47-year-old female was seen initially in 2007 with adenocarcinoma of the bladder dome for which she underwent partial cystectomy. She presented in 2011 with a left lung mass and mediastinal adenopathy. Bronchoscopy showed an endobronchial lesion from which brushings were obtained. These showed numerous groups of columnar cells with medium sized nuclei and abundant cytoplasm. The cells were positive for CK20 and CDX2 and negative for CK7. The cytomorphological findings were similar to those in the previous resection specimen and concurrent biopsy. This is the first case report of bronchial brushings containing metastatic urachal carcinoma. No specific immunohistochemical profile is available for its diagnosis. The consideration of a second primary was a distinct possibility in this case due to the lapse of time from primary resection, absence of local disease, and lack of regional metastases.

  4. A hybrid floating brush seal (HFBS) for improved sealing and wear performance in turbomachinery applications

    Science.gov (United States)

    Lattime, Scott Byran

    A conceptually new type of seal has been developed for gas turbine applications which dramatically reduces wear and leakage associated with current labyrinth and brush seal technologies. The Hybrid Floating Brush Seal (HFBS) combines brush seal and film riding face seal technologies to create a hybrid seal that allows both axial and radial excursions of the sealed shaft, while simultaneously eliminating interface surface speeds (friction and heat) between the rotor and the brush material that characterize standard brush seal technology. A simple test rig was designed to evaluate feasibility of the HFBS under relatively low pressures and rotational speeds (50psig, 5krpm). A second test stand was created to study the effects of centrifugal force on bristle deflection. A third test facility was constructed for prototype development and extensive room temperature testing at moderate pressures and fairly high rotational speeds (100psig, 40krpm). This test rig also allowed the evaluation of the HFBS during axial movement of a rotating shaft. An analytical model to predict the effects of centrifugal force on the bristles of a rotating brush seal was developed. Room temperature analysis of the HFBS proved successful for relatively high operating rotational velocities at moderate pressures with very acceptable leakage rates for gas turbine engines. Brush seals were able to track rotor speeds up to 24krpm while maintaining sealing integrity. The HFBS's ability to function under axial shaft displacement and synchronous dynamic radial loading was also proven successful. Hydrodynamic performance of the face seal was proven to provide adequate stiffness and load carrying capacity to keep the brush seal from contacting the face seal at pressure drops across the brush of up to 100psi. Leakage performance over standard brush seal and labyrinth technology was quite dramatic. The HFBS showed its sealing advantage using much higher radial interference between the rotor and the bristle

  5. Making strong polyelectrolyte brushes pH-sensitive by incorporation of gold nanoparticles.

    Science.gov (United States)

    Boyaciyan, D; Krause, P; von Klitzing, R

    2018-04-19

    Doping polymer brushes with gold nanoparticles (AuNPs) results in composite materials with colorimetric sensor properties. The present paper addresses the effect of electrostatic particle-particle interaction and the effect of the polymer brush type on particle assembly formation within the polymer matrix. The prospect for long-term use as colorimetric sensors is tested. Therefore, two different types of brushes of pH-insensitive polymers, non-ionic poly(N-isopropylacrylamide) (PNIPAM) and cationic poly-[2-(methacryloyloxy)ethyl] trimethylammonium chloride (PMETAC), are studied. After incubation of the non-ionic PNIPAM brush in an aqueous suspension of AuNPs with a pH-sensitive carboxylic acid capping, hydrogen binding led to attachment of the AuNPs, but they were easily detached at high pH due to loss of the hydrogen binding. In contrast, the anionic AuNPs adhere well to cationic PMETAC brushes even after post-treatment at low pH where the charge density of the AuNPs is strongly reduced. Therefore, the PMETAC/AuNP composites were further tested with respect to their stability against pH variations and their impact for colorimetric sensors. Although the neat PMETAC brush is not pH-sensitive, after embedding pH-sensitive AuNPs, the PMETAC/AuNP composite becomes pH-sensitive in a reversible manner. This is detectable by the reversible shift of the plasmon band and the reversible thickness change of the composites by exposing them to different pH.

  6. Polymer Brush-Functionalized Chitosan Hydrogels as Antifouling Implant Coatings.

    Science.gov (United States)

    Buzzacchera, Irene; Vorobii, Mariia; Kostina, Nina Yu; de Los Santos Pereira, Andres; Riedel, Tomáš; Bruns, Michael; Ogieglo, Wojciech; Möller, Martin; Wilson, Christopher J; Rodriguez-Emmenegger, Cesar

    2017-06-12

    Implantable sensor devices require coatings that efficiently interface with the tissue environment to mediate biochemical analysis. In this regard, bioinspired polymer hydrogels offer an attractive and abundant source of coating materials. However, upon implantation these materials generally elicit inflammation and the foreign body reaction as a consequence of protein fouling on their surface and concomitant poor hemocompatibility. In this report we investigate a strategy to endow chitosan hydrogel coatings with antifouling properties by the grafting of polymer brushes in a "grafting-from" approach. Chitosan coatings were functionalized with polymer brushes of oligo(ethylene glycol) methyl ether methacrylate and 2-hydroxyethyl methacrylate using photoinduced single electron transfer living radical polymerization and the surfaces were thoroughly characterized by XPS, AFM, water contact angle goniometry, and in situ ellipsometry. The antifouling properties of these new bioinspired hydrogel-brush coatings were investigated by surface plasmon resonance. The influence of the modifications to the chitosan on hemocompatibility was assessed by contacting the surfaces with platelets and leukocytes. The coatings were hydrophilic and reached a thickness of up to 180 nm within 30 min of polymerization. The functionalization of the surface with polymer brushes significantly reduced the protein fouling and eliminated platelet activation and leukocyte adhesion. This methodology offers a facile route to functionalizing implantable sensor systems with antifouling coatings that improve hemocompatibility and pave the way for enhanced device integration in tissue.

  7. The synthesis of hydrogels with controlled distribution of polymer brushes in hydrogel network

    Energy Technology Data Exchange (ETDEWEB)

    Sun, YuWei; Zhou, Chao; Zhang, AoKai; Xu, LiQun; Yao, Fang [School of Chemistry and Chemical Engineering, Southeast University, Jiangning District, Nanjing, Jiangsu Province, 211189 (China); Cen, Lian, E-mail: cenlian@hotmail.com [National Tissue Engineering Center of China, No.68, East Jiang Chuan Road, Shanghai, 200241 (China); School of Chemical Engineering, East China University of Science and Technology, No.130, Mei Long Road, Shanghai, 200237 (China); Fu, Guo-Dong, E-mail: fu7352@seu.edu.cn [School of Chemistry and Chemical Engineering, Southeast University, Jiangning District, Nanjing, Jiangsu Province, 211189 (China)

    2014-11-30

    Highlights: • Many biological tissues are 3-dimensionally asymmetric in structure and properties, it would be desirable if hydrogels could bear such structural similarity with specialized surface and bulk properties. Moreover, gradual but continuous variation in spatial structural and property is also a common phenomenon in biological tissues, such as interfaces between bone and tendon, or between bone and cartilage. Hence, the development of a method to introduce well-defined functional polymer brushes on PEG hydrogels, especially with precisely controlled spatial structure in 3-dimensions, would impart the hydrogels with special functionalities and wider applications. Poly(ethylene glycol) (PEG) hydrogels with 3-dimensionally controlled well-defined poly(N-isopropylacrylamide) (poly(NIPAAm)) brushes were prepared by combined copper(I)-catalyzed azide-alkyne cycloaddition (“Click Chemistry”) and atom transfer radical polymerization (ATRP). The resulting hydrogels were presented as representatives with their detailed synthesis routes and characterization. H{sub PEG}-S-poly(NIPAAm) is a hydrogel with poly(NIPAAm) brushes mainly grafted on surface, whereas H{sub PEG}-G-poly(NIPAAm) has a gradiently decreased poly(NIPAAm) brushes in their chain length from surface to inside. On the other hand, poly(NIPAAm) brushes in H{sub PEG}-U-poly(NIPAAm) are uniformly dispersed throughout the whole hydrogel network. Successful preparation of H{sub PEG}-S-poly(NIPAAm), H{sub PEG}-G-poly(NIPAAm) and H{sub PEG}-U-poly(NIPAAm) were ascertained by X-ray photoelectron spectroscopy (XPS) and water contact angle measurement. Hence, the flexibility and controllability of the synthetic strategy in varying the distribution of polymer brushes and hydrogel surface properties was demonstrated. Hydrogels with tunable and well-defined 3-dimensional poly(NIPAAm) polymer brushes could be tailor-designed to find potential applications in smart devices or skin dressing, such as for diabetics

  8. Peptides Displayed as High Density Brush Polymers Resist Proteolysis and Retain Bioactivity

    Science.gov (United States)

    2015-01-01

    We describe a strategy for rendering peptides resistant to proteolysis by formulating them as high-density brush polymers. The utility of this approach is demonstrated by polymerizing well-established cell-penetrating peptides (CPPs) and showing that the resulting polymers are not only resistant to proteolysis but also maintain their ability to enter cells. The scope of this design concept is explored by studying the proteolytic resistance of brush polymers composed of peptides that are substrates for either thrombin or a metalloprotease. Finally, we demonstrate that the proteolytic susceptibility of peptide brush polymers can be tuned by adjusting the density of the polymer brush and offer in silico models to rationalize this finding. We contend that this strategy offers a plausible method of preparing peptides for in vivo use, where rapid digestion by proteases has traditionally restricted their utility. PMID:25314576

  9. Spectroscopic study of a DNA brush synthesized in situ by surface initiated enzymatic polymerization.

    Science.gov (United States)

    Khan, M Nuruzzaman; Tjong, Vinalia; Chilkoti, Ashutosh; Zharnikov, Michael

    2013-08-29

    We used a combination of synchrotron-based X-ray photoelectron spectroscopy (XPS) and angle-resolved near-edge X-ray absorption fine structure (NEXAFS) spectroscopy to study the chemical integrity, purity, and possible internal alignment of single-strand (ss) adenine deoxynucleotide (poly(A)) DNA brushes. The brushes were synthesized by surface-initiated enzymatic polymerization (SIEP) on a 25-mer of adenine self-assembled monolayer (SAM) on gold (A25-SH), wherein the terminal 3'-OH of the A25-SH serve as the initiation sites for SIEP of poly(A). XPS and NEXAFS spectra of poly(A) brushes were found to be almost identical to those of A25-SH initiator, with no unambiguous traces of contamination. Apart from the well-defined chemical integrity and contamination-free character, the brushes were found to have a high degree of orientational order, with an upright orientation of individual strands, despite their large thickness up to ~55 nm, that corresponds to a chain length of at least several hundred nucleotides for individual ssDNA molecules. The orientational order exhibited by these poly(A) DNA brushes, mediated presumably by base stacking, was found to be independent of the brush thickness as long as the packing density was high enough. The well-defined character and orientational ordering of the ssDNA brushes make them a potentially promising system for different applications.

  10. Effect of tooth brushing on gloss retention and surface roughness of five bulk-fill resin composites.

    Science.gov (United States)

    O'Neill, Catherine; Kreplak, Laurent; Rueggeberg, Frederick A; Labrie, Daniel; Shimokawa, Carlos Alberto Kenji; Price, Richard Bengt

    2018-01-01

    To determine the effects of tooth brushing on five bulk-fill resin based composites (RBCs). Ten samples of Filtek Supreme Enamel (control), Filtek One Bulk Fill, Tetric EvoCeram Bulk Fill, SonicFill 2, SDR flow+, and Admira Fusion X-tra were light cured for 20 seconds using the Valo Grand curing light. After 24 hours storage in air at 37°C, specimens were brushed in a random order using Colgate OpticWhite dentifrice and a soft toothbrush. Surface gloss was measured prior to brushing, after 5,000, 10,000 and 15,000 back and forth brushing cycles. Surface roughness was measured after 15,000 brushing cycles using atomic force microscopy (AFM) and selected scanning electron microscope (SEM) images were taken. The data was examined using ANOVA and pair-wise comparisons using Scheffe's post-hoc multiple comparison tests (α = 0.05). Surface gloss decreased and the surface roughness increased after brushing. Two-way ANOVA showed that both the RBC and the number of brushing cycles had a significant negative effect on the gloss. One-way ANOVA showed that the RBC had a significant effect on the roughness after 15,000 brushing cycles. For both gloss and roughness, brushing had the least effect on the nano-filled control and nano-filled bulk-fill RBC, and the greatest negative effect on Admira Fusion X-tra. The SEM images provided visual agreement. There was an excellent linear correlation (R 2  = 0.98) between the logarithm of the gloss and roughness. After brushing, the bulk-fill RBCs were all rougher than the control nano-filled RBC. The nano-filled bulk-fill RBC was the least affected by brushing. Bulk-fill RBCs lose their gloss faster and become rougher than the nanofilled conventional RBC, Filtek Supreme Ultra. The nanofilled bulk-fill RBC was the least affected by tooth brushing. © 2017 Wiley Periodicals, Inc.

  11. Illela border market: origin and contributions to trans-border ...

    African Journals Online (AJOL)

    Illela border market: origin and contributions to trans-border relations between Nigeria and Niger republic. ... cordial relations between her and her immediate neighbours and thus stem the scourge of smuggling and other trans-border crimes which have negatively affected the Nigerian economy and her international image.

  12. Segment density profiles of polyelectrolyte brushes determined by Fourier transform ellipsometry

    Science.gov (United States)

    Biesalski, Markus; Rühe, Jürgen; Johannsmann, Diethelm

    1999-10-01

    We describe a method for the explicit determination of the segment density profile φ(z) of surface-attached polymer brushes with multiple angle of incidence null-ellipsometry. Because the refractive index contrast between the brush layer and the solvent is weak, multiple reflections are of minor influence and the ellipsometric spectrum is closely related to the Fourier transform of the refractive index profile, thereby allowing for explicit inversion of the ellipsometric data. We chose surface-attached monolayers of polymethacrylic acid (PMAA), a weak polyelectrolyte, as a model system and determined the segment density profile of this system as a function of the pH value of the surrounding medium by the Fourier method. Complementary to the Fourier analysis, fits with error functions are given as well. The brushes were prepared on the bases of high refractive index prisms with the "grafting-from" technique. In water, the brushes swell by more than a factor of 30. The swelling increases with increasing pH because of a growing fraction of dissociated acidic groups leading to a larger electrostatic repulsion.

  13. Structure of the vitreoretinal border region in spontaneously diabetic BB rats

    DEFF Research Database (Denmark)

    Heegaard, S

    1993-01-01

    The morphology of the vitreoretinal border region, also termed the inner limiting membrane, was examined in spontaneously diabetic rats (BB rats), in non-diabetes-prone rats (WB rats) and in Buffalo rats (BUF rats) by scanning electron microscopy (SEM) and transmission electron microscopy (TEM......). This was performed in order to visualize a possible increase in thickness of the lamina densa or in the whole vitreoretinal border region complex with duration of diabetes. The median thickness of the lamina densa in the three groups varied between 34 and 68 nm. In BB rats the thickness decreased with age...... and duration of diabetes. In WB rats the lamina densa thickened up to the 9th month and then decreased to the level of the young rats. In BUF rats the lamina densa decreased in thickness with age. The median thickness of the whole vitreoretinal border region varied between: BB rats: 84 and 126 nm (SEM) and 68...

  14. Description of fuel element brush assembly's fabrication for 105-K west

    International Nuclear Information System (INIS)

    Maassen, D.P.

    1997-01-01

    This report is a description of the process to redesign and fabricate, as well as, describe the features of the Fuel Element Brush Assembly used in the 105-K West Basin. This narrative description will identify problems that occurred during the redesigning and fabrication of the 105-K West Basin Fuel Element Brush Assembly and specifically address their solutions

  15. Structural analysis of paintings based on brush strokes

    Science.gov (United States)

    Sablatnig, Robert; Kammerer, Paul; Zolda, Ernestine

    1998-05-01

    The origin of works of art can often not be attributed to a certain artist. Likewise it is difficult to say whether paintings or drawings are originals or forgeries. In various fields of art new technical methods are used to examine the age, the state of preservation and the origin of the materials used. For the examination of paintings, radiological methods like X-ray and infra-red diagnosis, digital radiography, computer-tomography, etc. and color analyzes are employed to authenticate art. But all these methods do not relate certain characteristics in art work to a specific artist -- the artist's personal style. In order to study this personal style of a painter, experts in art history and image processing try to examine the 'structural signature' based on brush strokes within paintings, in particular in portrait miniatures. A computer-aided classification and recognition system for portrait miniatures is developed, which enables a semi- automatic classification and forgery detection based on content, color, and brush strokes. A hierarchically structured classification scheme is introduced which separates the classification into three different levels of information: color, shape of region, and structure of brush strokes.

  16. Development of Self-Assembled Nanoscale Templates via Microphase Separation Induced by Polymer Brushes

    Science.gov (United States)

    Chu, Elza

    Phase separation in soft matter has been the crucial element in generating hybrid materials, such as polymer blends and mixed polymer brushes. This dissertation discusses two methods of developing self-assembled nanoscale templates via microphase separation induced by polymer brush synthesis. This work introduces a novel soft substrate approach with renewable grafting sites where polyacrylamide is "grafted through" chitosan soft substrates. The mechanism of grafting leads to ordered arrays of filament-like nanostructures spanning the chitosan-air interface. Additionally, the chemical composition of the filaments allows for post-chemical modification to change the physical properties of the filaments, and subsequently tailor surfaces for specific application. Unlike traditional materials, multi-functional or "smart" materials, such as binary polymer brushes (BPB) are capable of spontaneously changing the spatial distribution of functional groups and morphology at the surface upon external stimuli. Although promising in principle, the limited range of available complementary polymers with common non-selective solvents confines the diversity of usable materials and restricts any further advancement in the field. This dissertation also covers the fabrication and characterization of responsive nanoscale polystyrene templates or "mosaic" brushes that are capable of changing interfacial composition upon exposure to varying solvent qualities. Using a "mosaic" brush template is a unique approach that allows the fabrication of strongly immiscible polymer BPB without the need for a common solvent. The synthesis of such BPB is exemplified by two strongly immiscible polymers, i.e. polystyrene (polar) and polyacrylamide (non-polar), where polyacrylamide brush is "graft through" a Si-substrate modified with the polystyrene collapsed "mosaic" brush. The surface exhibits solvent-triggered responses, as well as application potential for anti-biofouling.

  17. A Nanosecond Pulsed Plasma Brush for Surface Decontamination

    Science.gov (United States)

    Neuber, Johanna; Malik, Muhammad; Song, Shutong; Jiang, Chunqi

    2015-11-01

    This work optimizes a non-thermal, atmospheric pressure plasma brush for surface decontamination. The generated plasma plumes with a maximum length of 2 cm are arranged in a 5 cm long, brush-like array. The plasma was generated in ambient air with Acinetobacter baumannii. Laminate surfaces inoculated with over-night cultured bacteria were subject to the plasma treatment for varying water concentrations in He, flow rates and discharge voltages. It was found that increasing the water content of the feed gas greatly enhanced the bactericidal effect. Emission spectroscopy was performed to identify the reactive plasma species that contribute to this variation. Additional affiliation: Frank Reidy Research Center for Bioelectrics

  18. Border Encounters: American Cultural Politics and the U.S.-Mexico Border

    OpenAIRE

    Reimer, Jennifer Andrea

    2011-01-01

    AbstractBorder Encounters: American Cultural Politics and the U.S.-Mexico BorderbyJennifer Andrea ReimerDoctor of Philosophy in Ethnic StudiesUniversity of California, BerkeleyProfessor José David Saldívar, Co-ChairProfessor Laura E. Pérez, Co-ChairBorder Encounters: American Cultural Politics and the U.S.-Mexico Border is a transnational, interdisciplinary cultural study of the contemporary U.S.-Mexico border that argues for the critical role of the international border in the racial past, p...

  19. Molecular dynamics simulations of polyelectrolyte brushes under poor solvent conditions: origins of bundle formation.

    Science.gov (United States)

    He, Gui-Li; Merlitz, Holger; Sommer, Jens-Uwe

    2014-03-14

    Molecular dynamics simulations are applied to investigate salt-free planar polyelectrolyte brushes under poor solvent conditions. Starting above the Θ-point with a homogeneous brush and then gradually reducing the temperature, the polymers initially display a lateral structure formation, forming vertical bundles of chains. A further reduction of the temperature (or solvent quality) leads to a vertical collapse of the brush. By varying the size and selectivity of the counterions, we show that lateral structure formation persists and therefore demonstrate that the entropy of counterions being the dominant factor for the formation of the bundle phase. By applying an external compression force on the brush we calculate the minimal work done on the polymer phase only and prove that the entropy gain of counterions in the bundle state, as compared to the homogeneously collapsed state at the same temperature, is responsible for the lateral microphase segregation. As a consequence, the observed lateral structure formation has to be regarded universal for osmotic polymer brushes below the Θ-point.

  20. The Border Multiple

    DEFF Research Database (Denmark)

    Addressing and conceptualizing the changing character of borders in contemporary Europe, this book examines developments occurring in the light of European integration processes and an on-going tightening of Europe's external borders. Moreover, the book suggests new ways of investigating the nature...... of European borders by looking at border practices in the light of the mobility turn, and thus as dynamic, multiple, diverse and best expressed in everyday experiences of people living at and with borders, rather than focusing on static territorial divisions between states and regions at geopolitical level...

  1. The chemical modification and characterization of polypropylene membrane with environment response by in-situ chlorinating graft copolymerization

    Science.gov (United States)

    Zhang, Yue; Liu, Jiankai; Hu, Wenjie; Feng, Ying; Zhao, Jiruo

    2017-08-01

    In this study, a novel chemical surface modification method of polyolefin membranes is applied following the in-situ chlorinating graft copolymerization (ISCGC). Polypropylene (PP)/methyl methacrylate (MMA) system was used as an example. A unique structure was formed by the modification process on the original membrane surface and the product exhibited an environmental response. Chlorine free radicals were generated using ultraviolet and heat and were used to capture the hydrogen in the polymer chains on the substrate surface. The formed macromolecular radicals could react with MMA over 2 h to achieve a high coverage ratio polymer on the PP membrane surface. The graft copolymers were characterized using FTIR, 1H-NMR, DSC, and XPS, which all proved the feasibility of chemically modifying the PP membrane surface by ISCGC. The surface morphology of the grafted PP membrane was characterized using SEM and AFM. The results showed that the grafted product presents a uniform, neat, and dense mastoid structure with an average thickness of 4.44 μm, which was expected to be similar to the brush-like surface structure. The contact angle and AFM tests indicated that the product surface is responsive to solvent and pH. The experimental results showed that the PP membrane surface structure can be reconstructed using ISCGC, a method that can be used for environment-responsive polymer materials. Moreover, the product has the characteristics of polymer interfacial brush.

  2. Changes to Glazed Dental Ceramic Shade, Roughness, and Microhardness after Bleaching and Simulated Brushing.

    Science.gov (United States)

    Rodrigues, Carlos Roberto Teixeira; Turssi, Cecilia Pedroso; Amaral, Flávia Lucisano Botelho; Basting, Roberta Tarkany; França, Fabiana Mantovani Gomes

    2017-09-05

    To evaluate shade stability, surface roughness, microhardness, and compressive strength of a glazed feldspathic ceramic subjected to bleaching and simulated brushing. Eighty-eight glazed feldspathic ceramic specimens were made from microparticulate leucite and divided into eight groups (n = 10). The whitening products used were: Opalescence Trèswhite Supreme (Ultradent), Opalescence®\\ PF 15% (Ultradent), and Oral-B 3D White Whitestrips. All substances for whitening were used for 4 hours/day for a period of 14 days; the control group was not bleached. Next, half of the specimens were individually brushed. Microhardness and surface roughness data were subjected to three-way ANOVA and Tukey test. The diametrical tensile strength data were subjected to two-way ANOVA. The shade change data were analyzed using Kruskal-Wallis, Mann-Whitney, and the Student-Newman-Keuls test. The significance level was set at 5%. Glazed feldspathic ceramic surface microhardness was significantly affected by bleaching agents (p = 0.007). Initially, glazed ceramic microhardness was significantly higher than that observed after contact with the bleaching agents, whether or not brushing was performed. The specimens submitted to bleaching in preloaded trays presented lower surface roughness values after brushing (p = 0.037). The surface roughness was significantly lower in the brushed specimens (p = 0.044). The diametrical tensile strength was not significantly affected by the application of bleaching agents (p = 0.563) or by brushing (p = 0.477). When the specimens were brushed, however, shade change was significantly influenced by the bleaching agent used (p = 0.041). Bleaching agents associated with brushing cycles can alter surface properties and shade stability of glazed feldspathic ceramics, though such findings may not reflect the performance of unglazed feldspathic ceramics. © 2017 by the American College of Prosthodontists.

  3. 21 CFR 884.1100 - Endometrial brush.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Endometrial brush. 884.1100 Section 884.1100 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL...) Indication: Only to evaluate the endometrium, and (ii) Contraindications: Pregnancy, history of uterine...

  4. Heat-Induced Structural Changes Affect OVA-Antigen Processing and Reduce Allergic Response in Mouse Model of Food Allergy

    Czech Academy of Sciences Publication Activity Database

    Goliáš, Jaroslav; Schwarzer, Martin; Wallner, M.; Kverka, Miloslav; Kozáková, Hana; Šrůtková, Dagmar; Klimešová, Klára; Šotkovský, Petr; Palová-Jelínková, Lenka; Ferreira, F.; Tučková, Ludmila

    2012-01-01

    Roč. 7, č. 5 (2012), s. 1-10 E-ISSN 1932-6203 R&D Projects: GA ČR GA310/07/0414; GA ČR GD310/08/H077; GA AV ČR IAA500200801; GA AV ČR IAA500200710; GA AV ČR KJB500200904; GA MŠk 2B06155; GA MŠk LC07017 Institutional research plan: CEZ:AV0Z50200510 Keywords : BRUSH-BORDER MEMBRANES * BIRCH POLLEN ALLERGEN * MURINE MODEL Subject RIV: EC - Immunology Impact factor: 3.730, year: 2012

  5. Renal cortex taurine content regulates renal adaptive response to altered dietary intake of sulfur amino acids.

    OpenAIRE

    Chesney, R W; Gusowski, N; Dabbagh, S

    1985-01-01

    Rats fed a reduced sulfur amino acid diet (LTD) or a high-taurine diet (HTD) demonstrate a renal adaptive response. The LTD results in hypotaurinuria and enhanced brush border membrane vesicle (BBMV) accumulation of taurine. The HTD causes hypertaurinuria and reduced BBMV uptake. This adaptation may relate to changes in plasma or renal cortex taurine concentration. Rats were fed a normal-taurine diet (NTD), LTD, or HTD for 14 d or they underwent: (a) 3% beta-alanine for the last 8 d of each d...

  6. Friction Properties of Carbon Fiber Brush

    OpenAIRE

    大塚, 由佳; 月山, 陽介; 野老山, 貴行; 梅原, 徳次; OHTSUKA, Yuka; TSUKIYAMA, Yosuke; TOKOROYAMA, Takayuki; UMEHARA, Noritsugu

    2011-01-01

    直径数μmのカーボンファイバーを束ねたカーボンファイバーブラシ材料と金属材料のすべり摩擦におけるすべり出しの摩擦及び平均摩擦特性と,金属同士のそれらの摩擦特性の相違を調べ,カーボンファイバーブラシ材料の摩擦の特異性を明らかにした. Friction properties as initial and average friction coefficient were investigated for carbon brush materials. Experimental results shows that static friction coefficient of carbon fiber brush is smaller than kinetic friction after a macro slip. This phenomena is different from the usual friction properties between metals. I...

  7. Effects of Protease, Phytase and a Bacillus sp. Direct-Fed Microbial on Nutrient and Energy Digestibility, Ileal Brush Border Digestive Enzyme Activity and Cecal Short-Chain Fatty Acid Concentration in Broiler Chickens

    Science.gov (United States)

    Murugesan, Ganapathi R.; Romero, Luis F.; Persia, Michael E.

    2014-01-01

    Two experiments were conducted to determine the effects of protease and phytase (PP) and a Bacillus sp. direct-fed microbial (DFM) on dietary energy and nutrient utilization in broiler chickens. In the first experiment, Ross 308 broiler chicks were fed diets supplemented with PP and DFM in a 2×2 factorial arrangement. The 4 diets (control (CON), CON + PP, CON + DFM, and CON + PP + DFM) were fed from 15–21 days of age. In Experiment 1, significant interaction (P≤0.01) between PP and DFM on the apparent ileal digestibility coefficient for starch, crude protein, and amino acid indicated that both additives increased the digestibility. Both additives increased the nitrogen retention coefficient with a significant interaction (P≤0.01). Although no interaction was observed, significant main effects (P≤0.01) for nitrogen-corrected apparent ME (AMEn) for PP or DFM indicated an additive response. In a follow-up experiment, Ross 308 broiler chicks were fed the same experimental diets from 1–21 days of age. Activities of ileal brush border maltase, sucrase, and L-alanine aminopeptidase were increased (P≤0.01) by PP addition, while a trend (P = 0.07) for increased sucrase activity was observed in chickens fed DFM, in Experiment 2. The proportion of cecal butyrate was increased (P≤0.01) by DFM addition. Increased nutrient utilization and nitrogen retention appear to involve separate but complementary mechanisms for PP and DFM, however AMEn responses appear to have separate and additive mechanisms. PMID:25013936

  8. Structures of Bordered Pits Potentially Contributing to Isolation of a Refilled Vessel from Negative Xylem Pressure in Stems of Morus australis Poir.: Testing of the Pit Membrane Osmosis and Pit Valve Hypotheses.

    Science.gov (United States)

    Ooeda, Hiroki; Terashima, Ichiro; Taneda, Haruhiko

    2017-02-01

    Two hypotheses have been proposed to explain the mechanism preventing the refilling vessel water from being drained to the neighboring functional vessels under negative pressure. The pit membrane osmosis hypothesis proposes that the xylem parenchyma cells release polysaccharides that are impermeable to the intervessel pit membranes into the refilling vessel; this osmotically counteracts the negative pressure, thereby allowing the vessel to refill. The pit valve hypothesis proposes that gas trapped within intervessel bordered pits isolates the refilling vessel water from the surrounding functional vessels. Here, using the single-vessel method, we assessed these hypotheses in shoots of mulberry (Morus australis Poir.). First, we confirmed the occurrence of xylem refilling under negative pressure in the potted mulberry saplings. To examine the pit membrane osmosis hypothesis, we estimated the semi-permeability of pit membranes for molecules of various sizes and found that the pit membranes were not semi-permeable to polyethylene glycol of molecular mass osmosis mechanism in mulberry would be unrealistically large. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  9. Revitalising Borders: Memory, Mobility and Materiality in a Latvian-Russian Border Region

    Directory of Open Access Journals (Sweden)

    Aija Lulle

    2016-04-01

    Full Text Available In this paper I investigate how an international border is 'revitalised' in political discourses as opposed to lived experiences. Based on narratives I have collected from border dwellers on both sides of the current border between Latvia and Rus-sia and placing them into a broader context of current border debates, I analyse how geographical and social mobility is remembered from Soviet times and reworked in current contexts. I argue that while politically the border is revitalised through aban-doning and forgetting the Soviet past and through the idea of constant threats in the future, locally it is revitalised through giving a life to the abandoned: memories of 'vigorous times' in life-courses and material things. People who dwell at the border did not move themselves: the international border moved several times in one cen-tury leaving border dwellers' memories and significant places on the 'other' side. I focus on how these borders were crossed in the past, how they are (not crossed now, and the social meanings assigned to these circumstances. In the current con-text I follow diverse paths of reasoning that describe how the uneven flow of goods and people through the Latvian-Russian border shapes the power dynamic against which the people living in the border area used to reconstruct imaginaries of 'Soviet times' versus 'Europe' and 'vigorous times' versus decline.

  10. Characterization of swollen structure of high-density polyelectrolyte brushes in salt solution by neutron reflectivity

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Motoyasu; Takahara, Atsushi [Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Terayama, Yuki [Graduate School of Engineering, Kyushu University (Japan); Hino, Masahiro [Reactor Research Institute, Kyoto University (Japan); Ishihara, Kazuhiko, E-mail: takahara@cstf.kyushu-u.ac.j [Graduate School of Engineering, University of Tokyo (Japan)

    2009-08-01

    Zwitterionic and cationic polyelectrolyte brushes on quartz substrate were prepared by surface-initiated atom transfer radical polymerization of 2-(methacryloyloxy)ethyl phosphorylcholine (MPC) and 2-(methacryloyloxy)ethyltrimethylammonium chloride (METAC), respectively. The effects of ionic strength on brush structure and surface properties of densely grafted polyelectrolyte brushes were analysed by neutron reflectivity (NR) measurements. NR at poly(METAC)/D{sub 2}O and poly(MPC)/D{sub 2}O interface revealed that the grafted polymer chains were fairly extended from the substrate surface, while the thickness reduction of poly(METAC) brush was observed in 5.6 M NaCl/D{sub 2}O solution due to the screening of the repulsive interaction between polycations by hydrated salt ions. Interestingly, no structural change was observed in poly(MPC) brush even in a salt solution probably due to the unique interaction properties of phosphorylcholine units.

  11. Surface Grafted Glycopolymer Brushes to Enhance Selective Adhesion of HepG2 Cells

    DEFF Research Database (Denmark)

    Chernyy, Sergey; Jensen, Bettina Elisabeth Brøgger; Shimizu, Kyoko

    2013-01-01

    on the polymerization kinetics of 2-lactobionamidoethyl methacrylate) (LAMA) monomer on thermally oxidized silicon wafer. Both monolayer and multilayered aminosilane precursor layers have been prepared followed by reaction with 2-bromoisobutyrylbromide to form the ATRP initiator layer. It is inferred from the kinetic...... studies that the rate of termination is low on a multilayered initiator layer compared to a disordered monolayer structure. However both initiator types results in similar graft densities. Furthermore, it is shown that thick comb-like poly(LAMA) brushes can be constructed by initiating a second ATRP...... process on a previously formed poly(LAMA) brushes. The morphology of human hepatocellular carcinoma cancer cells (HepG2) on the comb-like poly(LAMA) brush layer has been studied. The fluorescent images of the HepG2 cells on the glycopolymer brush surface display distinct protrusions that extend outside...

  12. Anthrax in Vintage Animal-hair Shaving Brushes

    Centers for Disease Control (CDC) Podcasts

    2017-08-08

    Dr. Kate Hendricks, a CDC anthrax expert, discusses anthrax in vintage shaving brushes.  Created: 8/8/2017 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 8/8/2017.

  13. Polyelectrolyte Properties in Mono and Multi-Valent Ionic Media: Brushes and Complex Coacervates

    Science.gov (United States)

    Farina, Robert M.

    Materials composed of polyelectrolytes have unique and interesting physical properties resulting primarily from their charged monomer segments. Polyelectrolytes, which exist in many different biological and industrial forms, have also been shown to be highly responsive to external environmental changes. Here, two specific polyelectrolyte systems, brushes and complex coacervates, are discussed in regards to how their properties can be tailored by adjusting the surrounding ionic environment with mono and multi-valent ions. End-tethered polyelectrolyte brushes, which constitute an interesting and substantial portion of polyelectrolyte applications, are well known for their ability to provide excellent lubrication and low friction when coated onto surfaces (e.g. articular cartilage and medical devices), as well as for their ability to stabilize colloidal particles in solution (e.g. paint and cosmetic materials). These properties have been extensively studied with brushes in pure mono-valent ionic media. However, polyelectrolyte brush interactions with multi-valent ions in solution are much less understood, although highly relevant considering mono and multi-valent counterions are present in most applications. Even at very low concentrations of multi-valent ions in solution, dramatic polyelectrolyte brush physical property changes can occur, resulting in collapsed chains which also adhere to one another via multi-valent bridging. Here, the strong polyelectrolyte poly(sodium styrene sulfonate) was studied using the Surface Forces Apparatus (SFA) and electrochemistry in order to investigate brush height and intermolecular interactions between two brushes as a function of multi-valent counterion population inside a brush. Complex coacervates are formed when polyanions and polycations are mixed together in proper conditions of an aqueous solution. This mixing results in a phase separation of a polymer-rich, coacervate phase composed of a chain network held together via

  14. Obstructive jaundice: a comparative study of forceps and brush biopsy under percutaneous transhepatic cholangiography

    International Nuclear Information System (INIS)

    Li Yongdong; Han Xinwei; Wu Gang; Ma Bo; Xing Gusheng

    2004-01-01

    Objective: To compare the sensitivity between forceps biopsy and brushing, and to explore a feasible approach to pathological diagnosis of the obstructive jaundice. Methods: 92 consecutive patients with obstructive jaundice underwent transluminal forceps biopsy and brushing during percutaneous transhepatic cholangiography and percutaneous transhepatic cholangiodrainage. The technique was performed through a preexisting percutaneous transhepatic tract with multiple specimens obtained after passing the forceps biopsy or brush into a 8-French sheath. Finally the specimens were fixed with formalin for pathologic or cytologic diagnosis. Results: The histopathologic diagnosis was acquired in 81 out of 92 patients with forceps biopsy reaching the successful rate of 97.83%. Sensitivity of forceps biopsy in 92 patients was higher than that of brush in 84 patients (88.04% vs 76.19% χ 2 =4.251, P= <0.05). Conclusions: Percutaneous transhepatic cholangiobiopsy is a simple technique with minimal invasion, high sensitivity and worthy to be used spread extensively. Percutaneous transluminal brush cytology is also an useful method for establishing a diagnosis of cholangiocarcinoma. (authors)

  15. The Effect of Machining Conditions on the Forces in the Process of Roller Brush Machining

    Directory of Open Access Journals (Sweden)

    Jakub Matuszak

    2017-12-01

    Full Text Available Because of its advantages, brushing processing has many uses. The main ones include the removal of corrosion products, surface cleaning, deburring and shaping the properties of the surface layer. The intensity of these processes depends on the degree of impact of brush fibres on the work surface. In the case of tools, in which the resilient fibres are the working elements, forces in the brushing process, apart from the machining parameters, depend on the characteristics and overall dimensions of individual fibres. The paper presents the results of studies of the influence of technological parameters and type of fibres on the radial force in the brushing process.

  16. Self-consistent field theory of protein adsorption in a non-Gaussian polyelectrolyte brush

    NARCIS (Netherlands)

    Biesheuvel, P.M.; Leermakers, F.A.M.; Stuart, M.A.C.

    2006-01-01

    To describe adsorption of globular protein molecules in a polyelectrolyte brush we use the strong-stretching approximation of the Edwards self-consistent field equation, combined with corrections for a non-Gaussian brush. To describe chemical potentials in this mixture of (globular) species of

  17. Colon luminal content and epithelial cell morphology are markedly modified in rats fed with a high-protein diet.

    Science.gov (United States)

    Andriamihaja, Mireille; Davila, Anne-Marie; Eklou-Lawson, Mamy; Petit, Nathalie; Delpal, Serge; Allek, Fadhila; Blais, Anne; Delteil, Corine; Tomé, Daniel; Blachier, François

    2010-11-01

    Hyperproteic diets are used in human nutrition to obtain body weight reduction. Although increased protein ingestion results in an increased transfer of proteins from the small to the large intestine, there is little information on the consequences of the use of such diets on the composition of large intestine content and on epithelial cell morphology and metabolism. Rats were fed for 15 days with either a normoproteic (NP, 14% protein) or a hyperproteic isocaloric diet (HP, 53% protein), and absorptive colonocytes were observed by electron microscopy or isolated for enzyme activity studies. The colonic luminal content was recovered for biochemical analysis. Absorbing colonocytes were characterized by a 1.7-fold reduction in the height of the brush-border membranes (P = 0.0001) after HP diet consumption when compared with NP. This coincided in the whole colon content of HP animals with a 1.8-fold higher mass content (P = 0.0020), a 2.2-fold higher water content (P = 0.0240), a 5.2-fold higher protease activity (P = 0.0104), a 5.5-fold higher ammonia content (P = 0.0008), and a more than twofold higher propionate, valerate, isobutyrate, and isovalerate content (P hyperproteic diet ingestion causes marked changes both in the luminal environment of colonocytes and in the characteristics of these cells, demonstrating that hyperproteic diet interferes with colonocyte metabolism and morphology. Possible causal relationships between energy metabolism, reduced height of colonocyte brush-border membranes, and reduced water absorption are discussed.

  18. Scaling features of the tribology of polymer brushes of increasing grafting density around the mushroom-to-brush transition.

    Science.gov (United States)

    Mayoral, E; Klapp, J; Gama Goicochea, A

    2017-01-01

    Nonequilibrium coarse-grained, dissipative particle dynamics simulations of complex fluids, made up of polymer brushes tethered to planar surfaces immersed in a solvent yield nonmonotonic behavior of the friction coefficient as a function of the polymer grating density on the substrates, Γ, while the viscosity shows a monotonically increasing dependence on Γ. This effect is shown to be independent of the degree of polymerization, N, and the size of the system. It arises from the composition and the structure of the first particle layer adjacent to each surface that results from the confinement of the fluid. Whenever such layers are made up of as close a proportion of polymer beads to solvent particles as there are in the fluid, the friction coefficient shows a minimum, while for disparate proportions the friction coefficient grows. At the mushroom-to-brush transition (MBT) the viscosity scales with an exponent that depends on the characteristic exponent of the MBT (6/5) and the solvent quality exponent (ν=0.5, for θsolvent), but it is independent of the polymerization degree (N). On the other hand, the friction coefficient at the MBT scales as μ∼N^{6/5}, while the grafting density at the MBT scales as Γ∼N^{-6/5} when friction is minimal, in agreement with previous scaling theories. We argue these aspects are the result of cooperative phenomena that have important implications for the understanding of biological brushes and the design of microfluidics devices, among other applications of current academic and industrial interest.

  19. Development of plastic elongation in nanocrystalline and amorphous Ni–W dual phase alloys by brushing technique

    International Nuclear Information System (INIS)

    Nakayama, S.; Adachi, H.; Yamasaki, T.

    2015-01-01

    Highlights: • A novel agitation technique called the brushing technique is proposed. • A homogeneous material can be obtained with the brushing technique. • The brushed material exhibits large plastic elongation with work hardening. - Abstract: A novel agitation technique, referred to as the “brushing technique” is proposed to treat the surface of a Ni–W alloy film during electrodeposition. This technique was developed to directly remove hydrogen bubbles on the film surface and to apply Ni ions to the interfacial layer with the substrate. The intrinsic mechanical properties of the Ni–W electrodeposits are then evaluated with respect to application. High resolution transmission electron microscopy observations revealed that both treated and untreated films have nanocrystallites of approximately 5 nm in diameter and an amorphous phase. There was a compositional difference of about. 1.4 at% W between the face side and the reverse side of the film that was not subjected to the brushing technique, whereas this difference was absent in the film subjected to the brushing technique. In addition, the brushing technique reduced the surface roughness of the film and decreased the number of defects. As a result, a large plastic strain of about. 2.9% was observed with work hardening under tensile testing

  20. Interfacial Friction and Adhesion of Polymer Brushes

    KAUST Repository

    Landherr, Lucas J. T.; Cohen, Claude; Agarwal, Praveen; Archer, Lynden A.

    2011-01-01

    higher molar mass chains exhibit higher friction forces than those created using lower molar mass polymers. Increased grafting density of chains in the brush significantly reduces the COF by creating a uniform surface of stretched chains with a decreased

  1. RAFT-mediated synthesis of cationic poly[(ar-vinylbenzyl)trimethylammonium chloride] brushes for quantitative DNA immobilization

    International Nuclear Information System (INIS)

    Demirci, Serkan; Caykara, Tuncer

    2013-01-01

    The synthesis of cationic poly[(ar-vinylbenzyl)trimethylammonium chloride)] [poly(VBTAC)] brushes was achieved via reversible addition-fragmentation chain transfer (RAFT) polymerization and used for quantitative DNA immobilization. Initially, silicon surfaces were modified with RAFT chain transfer agent by utilizing an amide reaction involving a silicon wafer modified with allylamine and 4-cyanopentanoic acid dithiobenzoate (CPAD). Poly(VBTAC) brushes were then prepared via RAFT-mediated polymerization from the surface immobilized CPAD. Various characterization techniques including ellipsometry, X-ray photoelectron spectroscopy, grazing angle-Fourier transform infrared spectroscopy, atomic force microscopy and contact-angle goniometer were used to characterize the immobilization of CPAD on the silicon wafer and the subsequent polymer formation. The addition of free CPAD was required for the formation of well-defined polymer brushes, which subsequently resulted in the presence of free polymer chains in solution. The free polymer chains were isolated and used to estimate the molecular weights and polydispersity index of chains attached to the surface. Moreover, from atomic force microscopy and ellipsometry measurements, it was also determined that the density of immobilized DNA on the cationic poly(VBTAC) brushes can be quantitatively controlled by adjusting the solution concentration. Highlights: ► The cationic poly(VBTAC) brushes were prepared by RAFT polymerization. ► Grafting density of cationic poly(VBTAC) brushes was as high as 0.76 chains/nm 2 . ► The cationic poly(VBTAC) brushes were used for quantitative DNA immobilization.

  2. Mechanisms of mercurial and arsenical inhibition of tyrosine absorption in intestine of the winter flounder Pseudopleuronectus americanus

    International Nuclear Information System (INIS)

    Musch, M.W.; Chauncey, B.; Schmid, E.C.; Kinne, R.K.; Goldstein, L.

    1990-01-01

    Effects of HgCl2 (100 microM) para-chloromercuribenzene sulfonate (PCMBS) (1 mM), and oxophenylarsine (OPA) (250 microM) were determined on (a) the rate of Na pump activity in intact winter flounder intestine; (b) activity of Na-K-ATPase in tissue homogenates; and (c) Na-dependent and Na-independent uptake of tyrosine in brush border membrane vesicles. Initial rate of uptake (influx) of 86Rb from the serosal solution of tissues mounted in Ussing chambers, a measure of Na-K-ATPase activity in the intact cell, was inhibited by all three agents with differing time courses. Rapidly permeating HgCl2 inhibited influx to the same degree as ouabain at 30 min, whereas the effects of PCMBS and OPA required 90 min. Cell potassium was also measured as an indirect indicator of ATPase activity and cell membrane permeability. All three agents decreased cell K, although effects on cell K lagged behind those for inhibition of the ATPase. At the concentrations used in the Ussing chamber (or at one-tenth concentration), all agents completely inhibited Na-K-ATPase activity in enzyme assays performed with tissue homogenates. In contrast, only HgCl2 decreased Na-dependent uptake of tyrosine by brush border membrane vesicles. These results suggest that mercurial and arsenical effects on tyrosine absorption are due to inhibition of the Na-K-ATPase thus decreasing the driving force for the cellular uptake by the Na-tyrosine cotransport system. Direct effects on Na-tyrosine cotransport may play a role in the inhibition observed with HgCl2, but not for PCMBS or OPA

  3. Effects of carbon brush anode size and loading on microbial fuel cell performance in batch and continuous mode

    KAUST Repository

    Lanas, Vanessa; Ahn, Yongtae; Logan, Bruce E.

    2014-01-01

    Larger scale microbial fuel cells (MFCs) require compact architectures to efficiently treat wastewater. We examined how anode-brush diameter, number of anodes, and electrode spacing affected the performance of the MFCs operated in fed-batch and continuous flow mode. All anodes were initially tested with the brush core set at the same distance from the cathode. In fed-batch mode, the configuration with three larger brushes (25 mm diameter) produced 80% more power (1240 mW m-2) than reactors with eight smaller brushes (8 mm) (690 mW m-2). The higher power production by the larger brushes was due to more negative and stable anode potentials than the smaller brushes. The same general result was obtained in continuous flow operation, although power densities were reduced. However, by moving the center of the smaller brushes closer to the cathode (from 16.5 to 8 mm), power substantially increased from 690 to 1030 mW m-2 in fed batch mode. In continuous flow mode, power increased from 280 to 1020 mW m-2, resulting in more power production from the smaller brushes than the larger brushes (540 mW m-2). These results show that multi-electrode MFCs can be optimized by selecting smaller anodes, placed as close as possible to the cathode. © 2013 Elsevier B.V. All rights reserved.

  4. Effects of carbon brush anode size and loading on microbial fuel cell performance in batch and continuous mode

    KAUST Repository

    Lanas, Vanessa

    2014-02-01

    Larger scale microbial fuel cells (MFCs) require compact architectures to efficiently treat wastewater. We examined how anode-brush diameter, number of anodes, and electrode spacing affected the performance of the MFCs operated in fed-batch and continuous flow mode. All anodes were initially tested with the brush core set at the same distance from the cathode. In fed-batch mode, the configuration with three larger brushes (25 mm diameter) produced 80% more power (1240 mW m-2) than reactors with eight smaller brushes (8 mm) (690 mW m-2). The higher power production by the larger brushes was due to more negative and stable anode potentials than the smaller brushes. The same general result was obtained in continuous flow operation, although power densities were reduced. However, by moving the center of the smaller brushes closer to the cathode (from 16.5 to 8 mm), power substantially increased from 690 to 1030 mW m-2 in fed batch mode. In continuous flow mode, power increased from 280 to 1020 mW m-2, resulting in more power production from the smaller brushes than the larger brushes (540 mW m-2). These results show that multi-electrode MFCs can be optimized by selecting smaller anodes, placed as close as possible to the cathode. © 2013 Elsevier B.V. All rights reserved.

  5. Surface interaction forces of cellulose nanocrystals grafted with thermoresponsive polymer brushes.

    Science.gov (United States)

    Zoppe, Justin O; Osterberg, Monika; Venditti, Richard A; Laine, Janne; Rojas, Orlando J

    2011-07-11

    The colloidal stability and thermoresponsive behavior of poly(N-isopropylacrylamide) brushes grafted from cellulose nanocrystals (CNCs) of varying graft densities and molecular weights was investigated. Indication of the grafted polymer brushes was obtained after AFM imaging of CNCs adsorbed on silica. Also, aggregation of the nanoparticles carrying grafts of high degree of polymerization was observed. The responsiveness of grafted CNCs in aqueous dispersions and as an ultrathin film was evaluated by using light scattering, viscosimetry, and colloidal probe microscopy (CPM). Light transmittance measurements showed temperature-dependent aggregation originating from the different graft densities and molecular weights. The lower critical solution temperature (LCST) of grafted poly(NiPAAm) brushes was found to decrease with the ionic strength, as is the case for free poly(NiPAAm) in aqueous solution. Thermal responsive behavior of grafted CNCs in aqueous dispersions was observed by a sharp increase in dispersion viscosity as the temperature approached the LCST. CPM in liquid media for asymmetric systems consisting of ultrathin films of CNCs and a colloidal silica probe showed the distinctive effects of the grafted polymer brushes on interaction and adhesive forces. The origin of such forces was found to be mainly electrostatic and steric in the case of bare and grafted CNCs, respectively. A decrease in the onset of attractive and adhesion forces of grafted CNCs films were observed with the ionic strength of the aqueous solution. The decreased mobility of polymer brushes upon partial collapse and decreased availability of hydrogen bonding sites with higher electrolyte concentration were hypothesized as the main reasons for the less prominent polymer bridging between interacting surfaces.

  6. Force-displacement measurements of earlywood bordered pits using a mesomechanical tester.

    Science.gov (United States)

    Zelinka, Samuel L; Bourne, Keith J; Hermanson, John C; Glass, Samuel V; Costa, Adriana; Wiedenhoeft, Alex C

    2015-10-01

    The elastic properties of pit membranes are reported to have important implications in understanding air-seeding phenomena in gymnosperms, and pit aspiration plays a large role in wood technological applications such as wood drying and preservative treatment. Here we present force-displacement measurements for pit membranes of circular bordered pits, collected on a mesomechanical testing system. The system consists of a quartz microprobe attached to a microforce sensor that is positioned and advanced with a micromanipulator mounted on an inverted microscope. Membrane displacement is measured from digital image analysis. Unaspirated pits from earlywood of never-dried wood of Larix and Pinus and aspirated pits from earlywood of dried wood of Larix were tested to generate force-displacement curves up to the point of membrane failure. Two failure modes were observed: rupture or tearing of the pit membrane by the microprobe tip, and the stretching of the pit membrane until the torus was forced out of the pit chamber through the pit aperture without rupture, a condition we refer to as torus prolapse. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

  7. Manufacturing of copper-graphite brushes for automobile applications

    International Nuclear Information System (INIS)

    Answar, M.Y.

    2006-01-01

    Copper-graphite brushes are used in high-volume automotive applications, such as ignition switches, window lifts, wiper motors, engine cooling fans, ABS break system and seat actuators etc. The amount of graphite in these brushes may range from 5 -20 wt. %. In this paper, some of the results of a study carried out using locally produced electrolytic copper powder and imported graphite powder are being summarized. The green compacts were produced by compaction at 650 MPa. These compacts were sintered at temperatures between 950 to 1050 degree C for various time intervals. The effects of sintering temperatures and time on the properties are analyzed. The influence of small additions of zinc on hardness of the sintered alloy compacts is also investigated. (author)

  8. Cross Sectional: bilateral parent-child interactions in school-age children's tooth-brushing behaviors.

    Science.gov (United States)

    Goh, Esther C L; Hsu, Stephen Chin-Ying

    2013-01-01

    The purpose of this study was to examine bilateral dynamics between parents and children in influencing children's tooth-brushing behaviors. In-depth conversational interviews-a specific qualitative method-were conducted with 38 parents in urban Xiamen, China and Singapore to learn insights into parental strategies for encouraging tooth-brushing habits in 6- to 9-year-old children. The interviews also examined the range of responses from children toward these parental strategies. Children usually do not comply with these tooth-brushing instructions from parents without a process of negotiation. Children's responses ranged from active resistant to compliant. Parents in Xiamen tended to use softer strategies and were more prone to be emotionally and behaviorally influenced by children's effort to thwart these strategies. Conversely, Singapore parents tended to demonstrate greater tenacity in negotiating with children. The process of developing children's tooth-brushing habits is not a unilateral from-parent-to-children process. Instead, it should be conceptualized as an ongoing interaction with bilateral power of influence from both parties.

  9. Novel Strategy for Photopatterning Emissive Polymer Brushes for Organic Light Emitting Diode Applications.

    Science.gov (United States)

    Page, Zachariah A; Narupai, Benjaporn; Pester, Christian W; Bou Zerdan, Raghida; Sokolov, Anatoliy; Laitar, David S; Mukhopadhyay, Sukrit; Sprague, Scott; McGrath, Alaina J; Kramer, John W; Trefonas, Peter; Hawker, Craig J

    2017-06-28

    A light-mediated methodology to grow patterned, emissive polymer brushes with micron feature resolution is reported and applied to organic light emitting diode (OLED) displays. Light is used for both initiator functionalization of indium tin oxide and subsequent atom transfer radical polymerization of methacrylate-based fluorescent and phosphorescent iridium monomers. The iridium centers play key roles in photocatalyzing and mediating polymer growth while also emitting light in the final OLED structure. The scope of the presented procedure enables the synthesis of a library of polymers with emissive colors spanning the visible spectrum where the dopant incorporation, position of brush growth, and brush thickness are readily controlled. The chain-ends of the polymer brushes remain intact, affording subsequent chain extension and formation of well-defined diblock architectures. This high level of structure and function control allows for the facile preparation of random ternary copolymers and red-green-blue arrays to yield white emission.

  10. The Border Multiple

    DEFF Research Database (Denmark)

    of European borders by looking at border practices in the light of the mobility turn, and thus as dynamic, multiple, diverse and best expressed in everyday experiences of people living at and with borders, rather than focusing on static territorial divisions between states and regions at geopolitical level...

  11. Real-time x-ray scattering study of the initial growth of organic crystals on polymer brushes

    Energy Technology Data Exchange (ETDEWEB)

    An, Sung Yup; Ahn, Kwangseok; Kim, Doris Yangsoo; Lee, Dong Ryeol, E-mail: drlee@ssu.ac.kr [Department of Physics, Soongsil University, Seoul 156-743 (Korea, Republic of); Lee, Hyun-Hwi [Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Cho, Jeong Ho, E-mail: jhcho94@skku.edu [Department of Chemical Engineering, SKKU Advanced Institute of Nanotechnology (SAINT) and Center for Human Interface Nano Technology (HINT), Sungkyunkwan University, Suwon 440-476 (Korea, Republic of)

    2014-04-21

    We studied the early-stage growth structures of pentacene organic crystals grown on polymer brushes using real-time x-ray scattering techniques. In situ x-ray reflectivity and atomic force microscopy analyses revealed that at temperatures close to the glass transition temperature of polymer brush, the pentacene overlayer on a polymer brush film showed incomplete condensation and 3D island structures from the first monolayer. A growth model based on these observations was used to quantitatively analyze the real-time anti-Bragg x-ray scattering intensities measured during pentacene growth to obtain the time-dependent layer coverage of the individual pentacene monolayers. The extracted total coverage confirmed significant desorption and incomplete condensation in the pentacene films deposited on the polymer brushes. These effects are ascribed to the change in the surface viscoelasticity of the polymer brushes around the glass transition temperature.

  12. Hydrogel brushes grafted from stainless steel via surface-initiated atom transfer radical polymerization for marine antifouling

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jingjing, E-mail: jjwang1@hotmail.com; Wei, Jun

    2016-09-30

    Highlights: • Crosslinked hydrogel brushes were grafted from SS surfaces for marine antifouling. • All brush-coated SS surfaces could effectively reduce the adhesion of biofouling. • The antifouling efficacy increased with the crosslinking density of hydrogels. - Abstract: Crosslinked hydrogel brushes were grafted from stainless steel (SS) surfaces for marine antifouling. The brushes were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) of 2-methacryloyloxyethyl phosphorylcholine (MPC) and poly(ethylene glycol) methyl ether methacrylate (PEGMA) respectively with different fractions of crosslinker in the feed. The grafted layers prepared with different thickness were characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), ellipsometry and water contact angle measurements. With the increase in the fraction of crosslinker in the feed, the thickness of the grafted layer increased and the surface became smooth. All the brush-coated SS surfaces could effectively reduce the adhesion of bacteria and microalgae and settlement of barnacle cyprids, as compared to the pristine SS surface. The antifouling efficacy of the PEGMA polymer (PPEGMA)-grafted surface was higher than that of the MPC polymer (PMPC)-grafted surfaces. Furthermore, the crosslinked hydrogel brush-grafted surfaces exhibited better fouling resistance than the non-crosslinked polymer brush-grafted surfaces, and the antifouling efficacy increased with the crosslinking density. These hydrogel coatings of low toxicity and excellent anti-adhesive characteristics suggested their useful applications as environmentally friendly antifouling coatings.

  13. Hydrogel brushes grafted from stainless steel via surface-initiated atom transfer radical polymerization for marine antifouling

    International Nuclear Information System (INIS)

    Wang, Jingjing; Wei, Jun

    2016-01-01

    Highlights: • Crosslinked hydrogel brushes were grafted from SS surfaces for marine antifouling. • All brush-coated SS surfaces could effectively reduce the adhesion of biofouling. • The antifouling efficacy increased with the crosslinking density of hydrogels. - Abstract: Crosslinked hydrogel brushes were grafted from stainless steel (SS) surfaces for marine antifouling. The brushes were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) of 2-methacryloyloxyethyl phosphorylcholine (MPC) and poly(ethylene glycol) methyl ether methacrylate (PEGMA) respectively with different fractions of crosslinker in the feed. The grafted layers prepared with different thickness were characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), ellipsometry and water contact angle measurements. With the increase in the fraction of crosslinker in the feed, the thickness of the grafted layer increased and the surface became smooth. All the brush-coated SS surfaces could effectively reduce the adhesion of bacteria and microalgae and settlement of barnacle cyprids, as compared to the pristine SS surface. The antifouling efficacy of the PEGMA polymer (PPEGMA)-grafted surface was higher than that of the MPC polymer (PMPC)-grafted surfaces. Furthermore, the crosslinked hydrogel brush-grafted surfaces exhibited better fouling resistance than the non-crosslinked polymer brush-grafted surfaces, and the antifouling efficacy increased with the crosslinking density. These hydrogel coatings of low toxicity and excellent anti-adhesive characteristics suggested their useful applications as environmentally friendly antifouling coatings.

  14. Surface changes of enamel after brushing with charcoal toothpaste

    Science.gov (United States)

    Pertiwi, U. I.; Eriwati, Y. K.; Irawan, B.

    2017-08-01

    The aim of this study was to determine the surface roughness changes of tooth enamel after brushing with charcoal toothpaste. Thirty specimens were brushed using distilled water (the first group), Strong® Formula toothpaste (the second group), and Charcoal® Formula toothpaste for four minutes and 40 seconds (equivalent to one month) and for 14 minutes (equivalent to three months) using a soft fleece toothbrush with a mass of 150 gr. The roughness was measured using a surface roughness tester, and the results were tested with repeated ANOVA test and one-way ANOVA. The value of the surface roughness of tooth enamel was significantly different (penamel.

  15. Fast discharging homopolar drum-type generator with gas bearing and flexible copper-fiber brushes

    International Nuclear Information System (INIS)

    Kibardin, A.S.; Komin, A.V.; Sojkin, V.F.; Frolkin, V.I.

    1984-01-01

    The description and results of testing schock-excited homopolar generator (SEHG) with a drum-type rotor, a gas bearing and flexible copper-fiber brushes are presented. SEHG has a magnetic core with two excitation coils with the designed field of 1.8-2 T in the gap. The drum-type titanium rotor has 80 kg, is 0.5 m in diameter, 0.25 m length and 0.05 m thick. SEHG power is 3.6 MJ, overall dimensions are 0.8x1 m. Single- and double-row bearings, representing an aluminium shell of 15 mm thick, established inside an external backward current lead and isolated from it, are used to control serviceability of a radial gas-static bearing, which is a support for an SEHG rotor. The bearing surface was covered with the colloidal graphite and had one or two rows by 24 openings for swelling. Brush units represent a bronze brush ring, containing 44 copper-fiber brushes. Tests results confirm serviceability of copper-fiber brushes with quite large dimensions and permit to count on producing the 2.4 MA electric discharge and 12 ms pulse rise time

  16. The effect of food location, heat load, and intrusive medical procedures on brushing activity in dairy cows.

    Science.gov (United States)

    Mandel, R; Whay, H R; Nicol, C J; Klement, E

    2013-10-01

    Animals allocate time and effort to a range of core (e.g., sleeping, feeding, drinking) and "luxury" (e.g., playing, exploring) activities. A luxury activity is characterized by low resilience and, as such, will be reduced when time or energy resources are limited, including under conditions of stress or discomfort. One seemingly luxurious activity available to cows on an increasing number of dairy farms is rubbing against an automated brush. The current study examined the effect of distance from food, heat load, and an intrusive medical procedure (i.e., artificial insemination and transrectal pregnancy examination) on the resilience of brush usage. The probability of using the brush decreased significantly when food was located distantly from the brush (mean=0.53) compared with days when food was located closer to the brush (mean=0.81). Brush usage also decreased at high temperature and humidity levels, with an average decrease of 0.062 brushing events for an increase of 1 temperature-humidity index unit (95% confidence interval=-0.93-0.030). In addition, a significant reduction of approximately 50% in brushing activity was observed on days of artificial insemination compared with the preceding 3d and the following 3d. These findings show that brush usage is a low resilience activity that reduces under a range of conditions. It may thus have the potential to be used as an indicator of a range of health and welfare problems in cows. Further research should be conducted to assess the sensitivity and specificity of this suggested tool and its possible contribution to the early detection of morbidity. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  17. Tooth brushing among 11- to 15-year-olds in Denmark: combined effect of social class and migration status.

    Science.gov (United States)

    Bast, L S; Nordahl, H; Christensen, L B; Holstein, B E

    2015-03-01

    Regular tooth brushing in adolescence predicts stable tooth brushing habits later in life. Differences in tooth brushing habits by ethnic background and socioeconomic position have been suggested. We investigated migration status and social class in relation to infrequent tooth brushing both separately and combined. The study population was 11-15 year-olds chosen from a clustered random sample of schools. Univariate and multivariate logistic regression analyses estimated the separate and combined effects of migration status and social class on less than twice daily tooth brushing. 10,607 respondents: a response rate of 88.3%. Boys of lower social class had higher odds ratio (OR) of infrequent tooth brushing than girls: 1.98 (95% confidence interval 1.62-2.41) vs 1.80 (1.53-2.24). Immigrants and descendants had higher odds compared to adolescents of Danish origin: immigrant boys OR 1.39 (1.05-1.89), girls OR 1.92 (1.47-2.50); descendant boys OR 2.53 (1.97-3.27), girls OR 2.56 (2.02-3.35). Analyses of the combined effect of social class and migration status showed that the social gradient in tooth brushing habits observed among ethnic Danes cannot be found among groups of immigrants and descendants. The study shows that both non-Danish origin and low social class increases the risk of infrequent tooth brushing among school-aged children. The study calls for in depth analyses of the processes which influence young people's tooth brushing habits. Further, there is a need to strengthen the promotion of appropriate tooth brushing habits of minority and low social class youths.

  18. Amphiphilic brushes from metallo-supramolecular block copolymers

    NARCIS (Netherlands)

    Guillet, P.; Fustin, C.A.; Wouters, D.; Höppener, S.; Schubert, U.S.; Gohy, J.M.W.

    2009-01-01

    A novel strategy to control the formation of amphiphilic brushes from metallo-supramol. block copolymers is described. The investigated copolymer consists of a polystyrene block linked to a poly(ethylene oxide) one via a charged bis-terpyridine ruthenium(ii) complex (PS-[Ru]-PEO). The initial

  19. Biologically Complex Planar Cell Plasma Membranes Supported on Polyelectrolyte Cushions Enhance Transmembrane Protein Mobility and Retain Native Orientation.

    Science.gov (United States)

    Liu, Han-Yuan; Chen, Wei-Liang; Ober, Christopher K; Daniel, Susan

    2018-01-23

    Reconstituted supported lipid bilayers (SLB) are widely used as in vitro cell-surface models because they are compatible with a variety of surface-based analytical techniques. However, one of the challenges of using SLBs as a model of the cell surface is the limited complexity in membrane composition, including the incorporation of transmembrane proteins and lipid diversity that may impact the activity of those proteins. Additionally, it is challenging to preserve the transmembrane protein native orientation, function, and mobility in SLBs. Here, we leverage the interaction between cell plasma membrane vesicles and polyelectrolyte brushes to create planar bilayers from cell plasma membrane vesicles that have budded from the cell surface. This approach promotes the direct incorporation of membrane proteins and other species into the planar bilayer without using detergent or reconstitution and preserves membrane constituents. Furthermore, the structure of the polyelectrolyte brush serves as a cushion between the planar bilayer and rigid supporting surface, limiting the interaction of the cytosolic domains of membrane proteins with this surface. Single particle tracking was used to analyze the motion of GPI-linked yellow fluorescent proteins (GPI-YFP) and neon-green fused transmembrane P2X2 receptors (P2X2-neon) and shows that this platform retains over 75% mobility of multipass transmembrane proteins in its native membrane environment. An enzyme accessibility assay confirmed that the protein orientation is preserved and results in the extracellular domain facing toward the bulk phase and the cytosolic side facing the support. Because the platform presented here retains the complexity of the cell plasma membrane and preserves protein orientation and mobility, it is a better representative mimic of native cell surfaces, which may find many applications in biological assays aimed at understanding cell membrane phenomena.

  20. Interaction between two parallel plates covered with a polyelectrolyte brush layer in an electrolyte solution.

    Science.gov (United States)

    Ohshima, Hiroyuki

    An approximate analytic expression is derived for the interaction energy between two parallel plates covered with a polyelectrolyte brush layer in an electrolyte solution. The interaction energy has three components: electrostatic interaction energy between two brush layers before and after their contact, steric interaction energy between two brush layers after their contact, and the van der Waals interaction energy between the cores of the plates. It is shown that these three components are of the same order of magnitude and contribute equally to the total interaction energy between two polyelectrolyte-coated plates in an electrolyte solution. On the basis of Derjaguin's approximation, an approximate expression for the interaction energy between two spherical particles covered with polyelectrolyte brush layers is also derived.

  1. A theoretical study of colloidal forces near an amphiphilic polymer brush

    Science.gov (United States)

    Wu, Jianzhong

    2011-03-01

    Polymer-based ``non-stick'' coatings are promising as the next generation of effective, environmentally-friendly marine antifouling systems that minimize nonspecific adsorption of extracellular polymeric substances (EPS). However, design and development of such systems are impeded by the poor knowledge of polymer-mediated interactions of biomacromolecules with the protected substrate. In this work, a polymer density functional theory (DFT) is used to predict the potential of mean force between spherical biomacromolecules and amphiphilic copolymer brushes within a coarse-grained model that captures essential nonspecific interactions such as the molecular excluded volume effects and the hydrophobic energies. The relevance of theoretical results for practical control of the EPS adsorption is discussed in terms of the efficiency of different brush configurations to prevent biofouling. It is shown that the most effective antifouling surface may be accomplished by using amphiphilic brushes with a long hydrophilic backbone and a hydrophobic end at moderate grafting density.

  2. The theory of reasoned action in describing tooth brushing, dental caries and diabetes adherence among diabetic patients.

    Science.gov (United States)

    Syrjälä, Anna-Maija H; Niskanen, Mirka C; Knuuttila, Matti L E

    2002-05-01

    Preventive oral health behaviour is important among diabetic patients, as it has been found that dental diseases and insulin-dependent diabetes mellitus (IDDM) have some psychological and biological factors in common. The aim here was to analyze the variables of Ajzen and Fishbein's theory of reasoned action to explain the reported frequency of tooth brushing, dental caries, HbA1c level and diabetes adherence. Cross-sectional data were gathered from 149 IDDM patients by means of a quantitative questionnaire, clinical examination and patient records. The results showed that a firmer intention to brush the teeth was related to a higher reported frequency of tooth brushing (p < 0.001). The attitude to and the subjective norm of tooth brushing were related to the intention to brush(p < 0.001) and to the reported frequency of tooth brushing. A better dental attitude was related to better diabetes adherence (p = 0.002) and fewer decayed surfaces (p = 0.01), and a firmer intention to brush the teeth was related to a lower HbA1c level (p = 0.015). Our results suggest that in oral health promotion among diabetic patients, both subjective norm and attitude are important and that diabetes adherence may be influenced by promoting dental attitude.

  3. Cigarette smoking, tooth brushing characteristics, and perceived ...

    African Journals Online (AJOL)

    This study was conducted among four hundred non-dental undergraduates of University of Benin, Benin City, Nigeria to assess the prevalence of cigarette smoking, tooth brushing characteristics, perceived efficacy in oral self-care and preventing gingivodental diseases among them. The result showed that the perceived ...

  4. Drilling Deeper into tooth brushing skills: Is proactive interference an under-recognized factor in oral hygiene behavior change?

    Science.gov (United States)

    Thavarajah, Rooban; Kumar, Madan; Mohandoss, Anusa Arunachalam; Vernon, Lance T

    2015-09-01

    Proper tooth brushing is a seemingly simple motor activity that can promote oral health. Applying health theories, such as the Information-Motivation-Behavioral Skills (IMB) model, Motivational Interviewing (MI) and Integrated Health Coaching (IHC), may help optimize tooth brushing technique in those with suboptimal skills. Some motor activities, including tooth brushing, may over time become rote and unconscious actions, such that an existing habit can inhibit new learning, i.e., exert proactive interference on learning the new skill. Proactive interference may impede the acquisition of new tooth brushing skills; thus, in this report, we: (1) Review how the habit of tooth brushing is formed; (2) Postulate how proactive interference could impede the establishment of proper tooth brushing retraining; (3) Discuss the merits of this hypothesis; and (4) Provide guidance for future work in this topic within the context of an approach to behavior change that integrates IMB, MI and IHC methodology.

  5. Border installations

    International Nuclear Information System (INIS)

    Lenaerts, Koen

    1988-01-01

    Border installations cover all nuclear plants located near the border with a neighbouring state. However, the actual distance depends on the context. The distance can vary considerably. Also the prohibition on siting near a heavily populated area also defines the actual distance variably. The distance criteria may be modified by other factors of topography, prevailing climate and so on. Various examples which illustrate the problems are given. For example, the Creys-Melville nuclear power plant is 80km from Geneva and the Cattonam installation is 12km from the French border with Luxembourg and Germany. The Cattenom case is explained and the legal position within the European Institutions is discussed. The French licensing procedures for nuclear power stations are described with special reference to the Cattenom power plant. Border installations are discussed in the context of European Community Law and Public International Law. (U.K.)

  6. A test for Creutzfeldt-Jakob disease using nasal brushings.

    Science.gov (United States)

    Orrú, Christina D; Bongianni, Matilde; Tonoli, Giovanni; Ferrari, Sergio; Hughson, Andrew G; Groveman, Bradley R; Fiorini, Michele; Pocchiari, Maurizio; Monaco, Salvatore; Caughey, Byron; Zanusso, Gianluigi

    2014-08-07

    Definite diagnosis of sporadic Creutzfeldt-Jakob disease in living patients remains a challenge. A test that detects the specific marker for Creutzfeldt-Jakob disease, the prion protein (PrP(CJD)), by means of real-time quaking-induced conversion (RT-QuIC) testing of cerebrospinal fluid has a sensitivity of 80 to 90% for the diagnosis of sporadic Creutzfeldt-Jakob disease. We have assessed the accuracy of RT-QuIC analysis of nasal brushings from olfactory epithelium in diagnosing sporadic Creutzfeldt-Jakob disease in living patients. We collected olfactory epithelium brushings and cerebrospinal fluid samples from patients with and patients without sporadic Creutzfeldt-Jakob disease and tested them using RT-QuIC, an ultrasensitive, multiwell plate-based fluorescence assay involving PrP(CJD)-seeded polymerization of recombinant PrP into amyloid fibrils. The RT-QuIC assays seeded with nasal brushings were positive in 30 of 31 patients with Creutzfeldt-Jakob disease (15 of 15 with definite sporadic Creutzfeldt-Jakob disease, 13 of 14 with probable sporadic Creutzfeldt-Jakob disease, and 2 of 2 with inherited Creutzfeldt-Jakob disease) but were negative in 43 of 43 patients without Creutzfeldt-Jakob disease, indicating a sensitivity of 97% (95% confidence interval [CI], 82 to 100) and specificity of 100% (95% CI, 90 to 100) for the detection of Creutzfeldt-Jakob disease. By comparison, testing of cerebrospinal fluid samples from the same group of patients had a sensitivity of 77% (95% CI, 57 to 89) and a specificity of 100% (95% CI, 90 to 100). Nasal brushings elicited stronger and faster RT-QuIC responses than cerebrospinal fluid (PCreutzfeldt-Jakob disease and indicated substantial prion seeding activity lining the nasal vault. (Funded by the Intramural Research Program of the National Institute of Allergy and Infectious Diseases and others.).

  7. A Test for Creutzfeldt–Jakob Disease Using Nasal Brushings

    Science.gov (United States)

    Orrú, Christina D.; Bongianni, Matilde; Tonoli, Giovanni; Ferrari, Sergio; Hughson, Andrew G.; Groveman, Bradley R.; Fiorini, Michele; Pocchiari, Maurizio; Monaco, Salvatore; Caughey, Byron; Zanusso, Gianluigi

    2014-01-01

    BACKGROUND Definite diagnosis of sporadic Creutzfeldt–Jakob disease in living patients remains a challenge. A test that detects the specific marker for Creutzfeldt–Jakob disease, the prion protein (PrPCJD), by means of real-time quaking-induced conversion (RT-QuIC) testing of cerebrospinal fluid has a sensitivity of 80 to 90% for the diagnosis of sporadic Creutzfeldt–Jakob disease. We have assessed the accuracy of RT-QuIC analysis of nasal brushings from olfactory epithelium in diagnosing sporadic Creutzfeldt– Jakob disease in living patients. METHODS We collected olfactory epithelium brushings and cerebrospinal fluid samples from patients with and patients without sporadic Creutzfeldt–Jakob disease and tested them using RT-QuIC, an ultrasensitive, multiwell plate–based fluorescence assay involving PrPCJD-seeded polymerization of recombinant PrP into amyloid fibrils. RESULTS The RT-QuIC assays seeded with nasal brushings were positive in 30 of 31 patients with Creutzfeldt–Jakob disease (15 of 15 with definite sporadic Creutzfeldt–Jakob disease, 13 of 14 with probable sporadic Creutzfeldt–Jakob disease, and 2 of 2 with inherited Creutzfeldt–Jakob disease) but were negative in 43 of 43 patients without Creutzfeldt–Jakob disease, indicating a sensitivity of 97% (95% confidence interval [CI], 82 to 100) and specificity of 100% (95% CI, 90 to 100) for the detection of Creutzfeldt–Jakob disease. By comparison, testing of cerebrospinal fluid samples from the same group of patients had a sensitivity of 77% (95% CI, 57 to 89) and a specificity of 100% (95% CI, 90 to 100). Nasal brushings elicited stronger and faster RT-QuIC responses than cerebrospinal fluid (PCreutzfeldt–Jakob disease and indicated substantial prion seeding activity lining the nasal vault. (Funded by the Intramural Research Program of the National Institute of Allergy and Infectious Diseases and others.) PMID:25099576

  8. Evaluation of a parent-designed programme to support tooth brushing of infants and young children*

    Science.gov (United States)

    Huebner, CE; Milgrom, P

    2015-01-01

    Objectives This study developed and tested an intervention to help parents establish a routine of brushing their young children’s teeth twice a day. Methods Community-based participatory research methods were used to engage parents in the design of the intervention to maximize its relevance and acceptability to others. Input was obtained by interviews and focus groups. The resulting intervention was four 90-min small-group sessions that provided educational information, direct instruction, practice and peer-to-peer problem-solving. A pre- to post-non-randomized design was used to evaluate the intervention’s effect to increase or maintain parents’ twice daily brushing. Results Intervention participants were 67 primary caregivers of children under six years of age. Of the 67 initial participants, 50 completed a post-intervention questionnaire administered 4 to 8 weeks following the intervention. The proportion of parents who reported brushing their young children’s teeth twice a day increased significantly from 59 per cent prior to the intervention to 89 per cent post-intervention (McNemar’s X2 = 10.71, P = 0.002). There were concomitant and statistically significant increases over the study period in parents’ confidence for brushing twice a day, attitudes about the importance of brushing and their self-efficacy for tooth brushing. Parents’ knowledge of children’s oral health, assessed by a 15-item scale developed for this study (‘Things to Know About Baby Teeth’), also increased significantly. Conclusions Twice daily tooth brushing is a low-cost, effective strategy to reduce the risk of childhood caries. As demonstrated here, community-based efforts can help parents achieve this important health behaviour. PMID:25070036

  9. Evaluation of a parent-designed programme to support tooth brushing of infants and young children.

    Science.gov (United States)

    Huebner, C E; Milgrom, P

    2015-02-01

    This study developed and tested an intervention to help parents establish a routine of brushing their young children's teeth twice a day. Community-based participatory research methods were used to engage parents in the design of the intervention to maximize its relevance and acceptability to others. Input was obtained by interviews and focus groups. The resulting intervention was four 90-min small-group sessions that provided educational information, direct instruction, practice and peer-to-peer problem-solving. A pre- to post-non-randomized design was used to evaluate the intervention's effect to increase or maintain parents' twice daily brushing. Intervention participants were 67 primary caregivers of children under six years of age. Of the 67 initial participants, 50 completed a post-intervention questionnaire administered 4 to 8 weeks following the intervention. The proportion of parents who reported brushing their young children's teeth twice a day increased significantly from 59 per cent prior to the intervention to 89 per cent post-intervention (McNemar's X(2)  = 10.71, P = 0.002). There were concomitant and statistically significant increases over the study period in parents' confidence for brushing twice a day, attitudes about the importance of brushing and their self-efficacy for tooth brushing. Parents' knowledge of children's oral health, assessed by a 15-item scale developed for this study ('Things to Know About Baby Teeth'), also increased significantly. Twice daily tooth brushing is a low-cost, effective strategy to reduce the risk of childhood caries. As demonstrated here, community-based efforts can help parents achieve this important health behaviour. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  10. Dual brush process for selective surface modification in graphoepitaxy directed self-assembly

    Science.gov (United States)

    Doise, Jan; Chan, Boon Teik; Hori, Masafumi; Gronheid, Roel

    2017-07-01

    Graphoepitaxy directed self-assembly is a potential low-cost solution for patterning via layers with pitches beyond the reach of a single optical lithographic exposure. In this process, selective control of the interfacial energy at the bottom and sidewall of the template is an important but challenging exercise. A dual brush process is implemented, in which two brushes with distinct end-groups are consecutively grafted to the prepattern to achieve fully independent modification of the bottom and sidewall surface of the template. A comprehensive study of hole pattern quality shows that using a dual brush process leads to a substantial improvement in terms of positional and dimensional variability across the process window. These findings will be useful to others who wish to manipulate polymer-surface interactions in directed self-assembly flows.

  11. Hierarchical antifouling brushes for biosensing applications

    Czech Academy of Sciences Publication Activity Database

    de los Santos Pereira, Andres; Riedel, Tomáš; Brynda, Eduard; Rodriguez-Emmenegger, Cesar

    2014-01-01

    Roč. 202, 31 October (2014), s. 1313-1321 ISSN 0925-4005 R&D Projects: GA ČR GAP205/12/1702; GA MŠk(CZ) EE2.3.30.0029; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:61389013 Keywords : hierarchically structured brushes * affinity biosensors * fouling Subject RIV: CE - Biochemistry Impact factor: 4.097, year: 2014

  12. Gallium-containing polymer brush film as efficient supported Lewis acid catalyst in a glass microreactor

    Directory of Open Access Journals (Sweden)

    Rajesh Munirathinam

    2013-08-01

    Full Text Available Polystyrene sulfonate polymer brushes, grown on the interior of the microchannels in a microreactor, have been used for the anchoring of gallium as a Lewis acid catalyst. Initially, gallium-containing polymer brushes were grown on a flat silicon oxide surface and were characterized by FTIR, ellipsometry, and X-ray photoelectron spectroscopy (XPS. XPS revealed the presence of one gallium per 2–3 styrene sulfonate groups of the polymer brushes. The catalytic activity of the Lewis acid-functionalized brushes in a microreactor was demonstrated for the dehydration of oximes, using cinnamaldehyde oxime as a model substrate, and for the formation of oxazoles by ring closure of ortho-hydroxy oximes. The catalytic activity of the microreactor could be maintained by periodic reactivation by treatment with GaCl3.

  13. Metrics for border management systems.

    Energy Technology Data Exchange (ETDEWEB)

    Duggan, Ruth Ann

    2009-07-01

    There are as many unique and disparate manifestations of border systems as there are borders to protect. Border Security is a highly complex system analysis problem with global, regional, national, sector, and border element dimensions for land, water, and air domains. The complexity increases with the multiple, and sometimes conflicting, missions for regulating the flow of people and goods across borders, while securing them for national security. These systems include frontier border surveillance, immigration management and customs functions that must operate in a variety of weather, terrain, operational conditions, cultural constraints, and geopolitical contexts. As part of a Laboratory Directed Research and Development Project 08-684 (Year 1), the team developed a reference framework to decompose this complex system into international/regional, national, and border elements levels covering customs, immigration, and border policing functions. This generalized architecture is relevant to both domestic and international borders. As part of year two of this project (09-1204), the team determined relevant relative measures to better understand border management performance. This paper describes those relative metrics and how they can be used to improve border management systems.

  14. Synthesis of thermoresponsive poly(N-isopropylacrylamide) brush on silicon wafer surface via atom transfer radical polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Turan, Eylem; Demirci, Serkan [Department of Chemistry, Faculty of Art and Science, Gazi University, 06500 Besevler, Ankara (Turkey); Caykara, Tuncer, E-mail: caykara@gazi.edu.t [Department of Chemistry, Faculty of Art and Science, Gazi University, 06500 Besevler, Ankara (Turkey)

    2010-08-31

    Thermoresponsive poly(N-isopropylacrylamide) [poly(NIPAM)] brush on silicon wafer surface was prepared by combining the self-assembled monolayer of initiator and atom transfer radical polymerization (ATRP). The resulting polymer brush was characterized by in situ reflectance Fourier transform infrared spectroscopy, atomic force microscopy and ellipsometry techniques. Gel permeation chromatography determination of the number-average molecular weight and polydispersity index of the brush detached from the silicon wafer surface suggested that the surface-initiated ATRP method can provide relatively homogeneous polymer brush. Contact angle measurements exhibited a two-stage increase upon heating over the board temperature range 25-45 {sup o}C, which is in contrast to the fact that free poly(NIPAM) homopolymer in aqueous solution exhibits a phase transition at ca. 34 {sup o}C within a narrow temperature range. The first de-wetting transition takes place at 27 {sup o}C, which can be tentatively attributed to the n-cluster induced collapse of the inner region of poly(NIPAM) brush close to the silicon surface; the second de-wetting transition occurs at 38 {sup o}C, which can be attributed to the outer region of poly(NIPAM) brush, possessing much lower chain density compared to that of the inner part.

  15. The association between parents' perceived social norms for toothbrushing and the frequency with which they report brushing their child's teeth.

    Science.gov (United States)

    Trubey, R J; Moore, S C; Chestnutt, I G

    2015-06-01

    To determine whether parents' judgements on how often other parents brush their children's teeth are associated with the frequency with which they brush their own children's teeth, and their satisfaction with their child's brushing routine. A cross-sectional questionnaire survey completed by 297 parents of children aged 3-6. Parents were asked how often they brushed their own child's teeth per week, how often they thought other parents did so, and how satisfied they were with their child's toothbrushing routine. Demographic data were also collected. The mean frequency that parents brushed their children's teeth was 12.5 times per week. Multiple regression analysis tested the relationship between parents' perceptions of other parents brushing frequency (mean 10.5 times per week) and how often they brushed their own child's teeth, controlling for socio-demographic factors, and yielded a positive association (p parents' satisfaction with their child's brushing routine and the extent to which they thought it was better than that of the average child (p Parents' judgements on how frequently other parents brush their children's teeth are associated with their own behaviour and satisfaction. Re-framing oral health messages to include some form of social normative information ("most parents do this") may prove more persuasive than simple prescriptive advice ("you should do this").

  16. Thermodynamics, electrostatics, and ionic current in nanochannels grafted with pH-responsive end-charged polyelectrolyte brushes.

    Science.gov (United States)

    Chen, Guang; Das, Siddhartha

    2017-03-01

    In this paper, we study the thermodynamics, electrostatics, and an external electric field driven ionic current in a pH-responsive, end-charged polyelectrolyte (PE) brush grafted nanochannel. By employing a mean field theory, we unravel a highly nonintuitive interplay of pH and electrolyte salt concentration in dictating the height of the end-charged PE brush. Larger pH or weak hydrogen ion concentration leads to maximum ionization of the charge-producing group-as a consequence, the resulting the electric double layer (EDL) energy get maximized causing a maximum deviation of the brush height from the value (d 0 ) of the uncharged brush. This deviation may result in enhancement or lowering of the brush height as compared to d 0 depending on whether the PE end locates lower or higher than h/2 (h is the nanochannel half height) and the salt concentration. Subsequently, we use this combined PE-brush-configuration-EDL-electrostatics framework to compute the ionic current in the nanochannel. We witness that the ionic current for smaller pH is much larger despite the corresponding magnitude of the EDL electrostatic potential being much smaller-this stems from the presence of a much larger concentration of H+ ions at small pH and the fact that H+ ions have very large mobilities. In fact, this ionic current shows a steep variation with pH that can be useful in exploring new designs for applications involving quantification and characterization of ionic current in PE-brush-grafted nanochannels. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Plaque-left-behind after brushing: intra-oral reservoir for antibacterial toothpaste ingredients

    OpenAIRE

    Otten, Marieke P. T.; Busscher, Henk J.; Abbas, Frank; van der Mei, Henny C.; van Hoogmoed, Chris G.

    2012-01-01

    Objectives Plaque is never fully removed by brushing and may act as a reservoir for antibacterial ingredients, contributing to their substantive action. This study investigates the contribution of plaque-left-behind and saliva towards substantivity of three antibacterial toothpastes versus a control paste without antibacterial claims. Materials and methods First, volunteers brushed 2 weeks with a control or antibacterial toothpaste. Next, plaque and saliva samples were collected 6 and 12 h af...

  18. Well-defined polyethylene molecular brushes by polyhomologation and ring opening metathesis polymerization

    KAUST Repository

    Zhang, Hefeng; Gnanou, Yves; Hadjichristidis, Nikolaos

    2014-01-01

    A novel strategy using polyhomologation and ring opening metathesis polymerization (ROMP) has been developed for the synthesis of well-defined polyethylene (PE) molecular brushes. Polyhomologation was used to afford an OH-terminated PE, which after transformation to the norbornyl PE macromonomer was subjected to ROMP. Kinetics of ROMP of the PE macromonomer was studied by in situ1H NMR monitoring. The brush structure was proved from HT-GPC, 1H NMR and DSC results.

  19. Magnetically Activated Self-Cleaning Membranes

    Science.gov (United States)

    2010-06-01

    potassium phthalimide was reacted with the brushes to attach the phthalimide group to the end of the brushes. Hydralization then yields a primary amine...Synthesis reaction For the first step of the Gabriel Synthesis, 1 g potassium phthalimide was dissolved into 20 mL of ethanol. This solution (4.5 mL...resulting polyacrylic acid (pAA) brushes 12 through an amide linkage. Grafting of pAA brushes was confirmed using two types of spectroscopy

  20. De novo expression of sodium-glucose cotransporter SGLT2 in Bowman's capsule coincides with replacement of parietal epithelial cell layer with proximal tubule-like epithelium.

    Science.gov (United States)

    Tabatabai, Niloofar M; North, Paula E; Regner, Kevin R; Kumar, Suresh N; Duris, Christine B; Blodgett, Amy B

    2014-08-01

    In kidney nephron, parietal epithelial cells line the Bowman's capsule and function as a permeability barrier for the glomerular filtrate. Bowman's capsule cells with proximal tubule epithelial morphology have been found. However, the effects of tubular metaplasia in Bowman's capsule on kidney function remain poorly understood. Sodium-glucose cotransporter 2 (SGLT2) plays a major role in reabsorption of glucose in the kidney and is expressed on brush border membrane (BBM) of epithelial cells in the early segment of the proximal tubule. We hypothesized that SGLT2 is expressed in tubularized Bowman's capsule and used our novel antibody to test this hypothesis. Immunohistochemical analysis was performed with our SGLT2 antibody on C57BL/6 mouse kidney prone to have tubularized Bowman's capsules. Cell membrane was examined with periodic acid-Schiff (PAS) stain. The results showed that SGLT2 was localized on BBM of the proximal tubules in young and adult mice. Bowman's capsules were lined mostly with normal brush border-less parietal epithelial cells in young mice, while they were almost completely covered with proximal tubule-like cells in adult mice. Regardless of age, SGLT2 was expressed on BBM of the tubularized Bowman's capsule but did not co-localize with nephrin in the glomerulus. SGLT2-expressing tubular cells expanded from the urinary pole toward the vascular pole of the Bowman's capsule. This study identified the localization of SGLT2 in the Bowman's capsule. Bowman's capsules with tubular metaplasia may acquire roles in reabsorption of filtered glucose and sodium.

  1. Pancreatic α-Amylase Controls Glucose Assimilation by Duodenal Retrieval through N-Glycan-specific Binding, Endocytosis, and Degradation*

    Science.gov (United States)

    Date, Kimie; Satoh, Ayano; Iida, Kaoruko; Ogawa, Haruko

    2015-01-01

    α-Amylase, a major pancreatic protein and starch hydrolase, is essential for energy acquisition. Mammalian pancreatic α-amylase binds specifically to glycoprotein N-glycans in the brush-border membrane to activate starch digestion, whereas it significantly inhibits glucose uptake by Na+/glucose cotransporter 1 (SGLT1) at high concentrations (Asanuma-Date, K., Hirano, Y., Le, N., Sano, K., Kawasaki, N., Hashii, N., Hiruta, Y., Nakayama, K., Umemura, M., Ishikawa, K., Sakagami, H., and Ogawa, H. (2012) Functional regulation of sugar assimilation by N-glycan-specific interaction of pancreatic α-amylase with glycoproteins of duodenal brush border membrane. J. Biol. Chem. 287, 23104–23118). However, how the inhibition is stopped was unknown. Here, we show a new mechanism for the regulation of intestinal glucose absorption. Immunohistochemistry revealed that α-amylase in the duodena of non-fasted, but not fasted, pigs was internalized from the pancreatic fluid and immunostained. We demonstrated that after N-glycan binding, pancreatic α-amylase underwent internalization into lysosomes in a process that was inhibited by α-mannoside. The internalized α-amylase was degraded, showing low enzymatic activity and molecular weight at the basolateral membrane. In a human intestinal Caco-2 cell line, Alexa Fluor 488-labeled pancreatic α-amylase bound to the cytomembrane was transported to lysosomes through the endocytic pathway and then disappeared, suggesting degradation. Our findings indicate that N-glycan recognition by α-amylase protects enterocytes against a sudden increase in glucose concentration and restores glucose uptake by gradual internalization, which homeostatically controls the postprandial blood glucose level. The internalization of α-amylase may also enhance the supply of amino acids required for the high turnover of small intestine epithelial cells. This study provides novel and significant insights into the control of blood sugar during the absorption

  2. Surface roughness and hardness of yttria stabilized zirconia (Y-TZP after 10 years of simulated brushing

    Directory of Open Access Journals (Sweden)

    Lucas Miguel Candido

    Full Text Available Introduction: The Y-TZP zirconia used for prosthetic infrastructure, in some clinical situations, can be exposed to the oral environment. In these situations, a polished surface without changes is extremely important. Objective: The aim of this study was to evaluate the mean roughness (Ra and Vickers hardness of Y-TZP zirconia (Lava™ after simulating ten years of brushing. Material and method: Thirty-six Y-TZP bar-shaped specimens (20mm X 4mm X 1.2mm were divided into three groups: storage in distilled water (DW, n=12, control; brushing with distilled water (BDW, n=12 and brushing with distilled water and fluoride toothpaste (BFT, n=12. Brushing was performed using a brushing machine with a soft-bristled toothbrush, simulating 10 years of brushing (878.400 cycles, 100gf. The mean roughness (Ra in μm and Vickers hardness (VHN of all specimens were measured twice: before and after the experimental treatment, in profilometer and microhardness tester (500gf, 30 seconds, respectively. Data were analyzed using the two-way ANOVA test (α = 0.05. Result: The interaction between groups was not significant for roughness (p = 0.701 nor for hardness (p = 0.928. The final averages for Ra (μm were equal to: DW - 0.63; BDW - 0.64; and, BFT - 0.68. The final averages for Vickers hardness (VHN were: DW - 1301.16; BDW - 1316.60; and, BFT - 1299.58. Conclusion: It was concluded that the brushing with distilled or fluoridated toothpaste was not able to change the roughness and hardness of Y-TZP zirconia used in this study.

  3. Brushed Target on Rock 'Champagne' in Gusev Crater

    Science.gov (United States)

    2005-01-01

    NASA's Mars Exploration Rover Spirit took this microscopic image of a target called 'Bubbles' on a rock called 'Champagne' after using its rock abrasion tool to brush away a coating of dust. The circular brushed area is about 5 centimeters (2 inches) across. This rock is different from rocks out on the plains of Gusev Crater but is similar to other rocks in this area of the 'Columbia Hills' in that it has higher levels of phosphorus. Plagioclase, a mineral commonly found in igneous rocks, is also present in these rocks, according to analysis with the minature thermal emission spectrometer. By using the alpha particle X-ray spectrometer to collect data over multiple martian days, or sols, scientists are also beginning to get measurements of trace elements in these rocks. Spirit took the images that are combined into this mosaic on sol 354 (Dec. 30, 2004).

  4. Insight into the electrical properties and chain conformation of spherical polyelectrolyte brushes by dielectric spectroscopy

    Science.gov (United States)

    Guo, Xiaoxia; Zhao, Kongshuang

    2017-02-01

    We report here a dielectric study on three kinds of anionic spherical polyelectrolyte brush (SPBs, consisting of a polystyrene (PS) core and three different poly (acrylic acid) chains grafted onto the core) suspensions over a frequency ranging from 40 Hz to 110 MHz. The relaxation behavior of the SPB suspensions shows significant changes in the brush-layer properties when the mass fraction of SPBs and the pH of the suspensions change. Two definite relaxations related to the interfacial polarization are observed around 100 kHz and 10 MHz. A single-layer spherical-shell model is applied to describe the SPB suspensions wherein the suspended SPB is modeled as a spherical-shell composite particle in which an insulated PS sphere is surrounded by a conducting ion-permeable shell (the polyelectrolyte chain layer). We developed the curve-fitting procedure to analyze the dielectric spectrum in order to obtain the dielectric properties of the components of the SPBs, especially the properties of the polyelectrolyte brush. Based on this method and model, the permittivity and conductivity of the brush layer, ζ potential, etc are calculated. The ordered orientation of the water molecules in the layer leads to an additional electrical dipole moment; increasing pH causes the brush layer to swell. In addition, the repulsive force between the SPB particles are evaluated using the brush-layer thickness, which is obtained by fitting dielectric spectra, combined with relative theoretical formulas. Increasing PH values or SPB concentration would improve the stability of the SPBs dispersion.

  5. Dynamic Properties of Star-Branched Polymer Brushes

    International Nuclear Information System (INIS)

    Sikorski, A.; Romiszowski, P.

    2004-01-01

    We studied a simplified model of a polymer brush. It consisted of star-branched chains, which were restricted to a simple cubic lattice. Each star-branched macromolecule consisted of three linear arms of equal length emanating from a common origin (the branching point). The chains were grafted to an impenetrable surface, i.e. they were terminally attached to the surface with one arm. The number of chains was varied from low to high grafting density. The model system was studied at good solvent conditions because the excluded volume effect was the only potential of interaction included in the model. The properties of this model system were studied by means of Monte Carlo simulation. The sampling algorithm was based on local changes of chain conformations. The dynamic properties of the polymer brush were studied and correlated with its structure. The differences in relaxation times of particular star arms were shown. The short-time mobility of polymer layers was analyzed. The lateral self-diffusion of chains was also studied and discussed. (author)

  6. The effect of brushing with nano calcium carbonate and calcium carbonate toothpaste on the surface roughness of nano-ionomer

    Science.gov (United States)

    Anisja, D. H.; Indrani, D. J.; Herda, E.

    2017-08-01

    Nanotechnology developments in dentistry have resulted in the development of nano-ionomer, a new restorative material. The surface roughness of restorative materials can increase bacteria adhesion and lead to poor oral hygiene. Abrasive agents in toothpaste can alter tooth and restorative material surfaces. The aim of this study is to identify the effect of brushing with nano calcium carbonate, and calcium carbonate toothpaste on surface roughness of nano-ionomer. Eighteen nano-ionomer specimens were brushed with Aquabidest (doubledistilled water), nano calcium carbonate and calcium carbonate toothpaste. Brushing lasted 30 minutes, and the roughness value (Ra) was measured after each 10 minute segment using a surface roughness tester. The data was analyzed using repeated ANOVA and one-way ANOVA test. The value of nano-ionomer surface roughness increased significantly (p<0.05) after 20 minutes of brushing with the nano calcium carbonate toothpaste. Brushing with calcium carbonate toothpaste leaves nano-ionomer surfaces more rugged than brushing with nano calcium carbonate toothpaste.

  7. Border Crossing/Entry Data - Border Crossing/Entry Data Time Series tool

    Data.gov (United States)

    Department of Transportation — The dataset is known as “Border Crossing/Entry Data.” The Bureau of Transportation Statistics (BTS) Border Crossing/Entry Data provides summary statistics to the...

  8. Chain-brush method in delimbing and debarking of wood; Ketjuharja-menetelmae puun karsinnassa ja kuorinnassa

    Energy Technology Data Exchange (ETDEWEB)

    Aho, V J; Nikala, L; Laitinen, H [VTT Energy, Jyvaeskylae (Finland)

    1997-12-01

    The objective of this project is to study, develop and make an integrated method for production of wood fuels and industrial raw material, promoting the competitiveness of the refining and energy usage of felling residues based on chain-brush delimbing-debarking technology, operational. VTT Energy has tested different brush constructions and the thickness of chains using varying feeding speeds and rotation speeds of the brush-delimber. First thinning pine, spruce and birch have been tested as single trees. Different temperatures have been used in the summer, and frozen timber in the winter. A method has been developed for estimation of the bark content and the wood losses for pine. The method is based on the measurement of the areas covered by bark and the debarked areas of the timber, on the bark thickness values and dry substance content of the wood obtained from the literature, as well as on the calculation formulas obtained from these. Unscrambler software will be used to assist the planning of the tests, and for analysing of the results. The utilisation of the chain-brush method for different wood-species, and the effect of different chain adjustments will be simulated by the software. The chain-brush delimbing will be studied using the high-speed camera acquired to VTT Energy. (orig.)

  9. Oral Health: Brush Up on Dental Care Basics

    Science.gov (United States)

    ... Mayo Clinic Staff Your smile depends on simple dental care habits, such as brushing and flossing. But are you using the right techniques? Follow these steps to protect your oral health. Oral health begins with clean teeth. Keeping the area where your teeth meet your ...

  10. Compartmentalised expression of meprin in small intestinal mucosa: enhanced expression in lamina propria in coeliac disease.

    Science.gov (United States)

    Lottaz, Daniel; Buri, Caroline; Monteleone, Giovanni; Rösmann, Sandra; Macdonald, Thomas T; Sanderson, Ian R; Sterchi, Erwin E

    2007-03-01

    Epithelial cells in the human small intestine express meprin, an astacin-like metalloprotease, which accumulates normally at the brush border membrane and in the gut lumen. Therefore, meprin is targeted towards luminal components. In coeliac disease patients, peptides from ingested cereals trigger mucosal inflammation in the small intestine, disrupting epithelial cell differentiation and function. Using in situ hybridisation on duodenal tissue sections, we observed a marked shift of meprin mRNA expression from epithelial cells, the predominant expression site in normal mucosa, to lamina propria leukocytes in coeliac disease. Meprin thereby gains access to the substrate repertoire present beneath the epithelium.

  11. The California Border Health Collaborative: A Strategy for Leading the Border to Better Health

    Directory of Open Access Journals (Sweden)

    Charles Edwards Matthews III

    2015-05-01

    Full Text Available There are hundreds of departments and organizations working on border health issues in the California/Baja California border region trying to protect and improve health without a collaborative structure that integrates jurisdictions and organizations. As a result, there is a need to effectively improve the health in the border region by coordinating these organizations to work together and benefit from each other’s best practices. The newly developed California Border Health Collaborative (CBHC can provide the leadership and collaborative culture to positively improve the health of the border region. This article aims to describe the development process of this collaborative to include key ingredients to success, the roles of mulit-level jurisdictions, and policy implications.This article describes the methods used to develop key aspects of collaborative leadership, strategic alignment and a common vision toward the building of this collective impact approach to border health. In addition, we describe the role of key local County (County of San Diego Live Well San Diego initiative, State, (California Department of Public Health- Office of Binational Border Health, Federal (US-Mexico Border Health Commission’s Leaders across Borders, Academia (e.g., University of California San Diego and San Diego State University and non-profit entities (e.g., Project Concern International, San Ysidro Health Center in forming the BHCC. Evaluating the consortium development process included a literature review of similar processes, a review of internal documents and an analysis of developmental events. To this point the CBHC has built a strong, cohesive collaborative on the U.S. side of the border. It is sharing and leveraging local expertise to address many border health issues. Even more importantly, the BHCC has reached a key stage in which it can effectively engage its Baja California, Mexico counterparts in a manner that will prove extremely powerful

  12. Borders as barriers to tourism: tourists experiences at the Beitbridge Border Post (Zimbabwean side

    Directory of Open Access Journals (Sweden)

    Getrude Kwanisai

    2014-01-01

    Full Text Available International borders greatly influence tourism development. In 2012 and 2013, a decline in tourists to Zimbabwe from South Africa was partially attributed to tourist border facilitation issues. It is against this background that this study sought to establish the nature of challenges faced by tourists when using the Beitbridge border post (Zimbabwean side. Questionnaire responses were thematically analysed and the study concluded that border administrative management related issues are a major barrier to tourism. Key among the study's recommendations is that the depressed tourists' border experiences obtaining at Beitbridge border post among other constraints have to be addressed as a matter of urgency. This will enhance Zimbabwe's accessibility, tourist satisfaction and the image of the country as a destination. The paper further identifies several destination managerial implications and future research priorities.

  13. Monitoring the Switching of Single BSA-ATTO 488 Molecules Covalently End-Attached to a pH-Responsive PAA Brush

    NARCIS (Netherlands)

    Akkilic, Namik; Molenaar, Robert; Claessens, Mireille Maria Anna Elisabeth; Blum, Christian; de Vos, Wiebe Matthijs

    2016-01-01

    We describe a novel combination of a responsive polymer brush and a fluorescently labeled biomolecule, where the position of the biomolecule can be switched from inside to outside the brush and vice versa by a change in pH. For this, we grafted ultrathin, amino-terminated poly(acrylic acid) brushes

  14. BORDERS AS AN INTERDISCPLINARY PROBLEM

    Directory of Open Access Journals (Sweden)

    Duško Vrban

    2018-04-01

    Full Text Available This article deals with the concepts of space and territoriality in law and politics seen through reflexion on borders, which are understood primarily as forms of identification and the basis for nation-building. While in the classical antiquity, borders were seen as exclusionary defensive structures, in modern international law in the 18th and 19th centuries, they became spaces for the delimitation of states sovereign territories. The author attempts to enligthen the symbolic significance of borders in modern European history, which have been connected with imperial designs, nationalist discourses and political imaginaries. Border rhetoric often emphasised territorial inclusions and exclusions relied to the concepts such as sovereignty, security and natural living space (“natural borders”. The concept of borders is also related to the understanding of the division of Earth’s surface into areas defined as regions. Regions may construct and transcend natural and political borders. Although, borders have been through world history sites of conflict, they also build ways of interconnections between locals and neighbours. The struggle over cultural and political domination and attempts to integrate and assimilate border populations were mostly reflected into deliberate linguistic policies relating to the language of administration and the public sphere. After the Second world war, the perception of borders have changed and the new understanding of borders have prevailed, based upon the idea of cooperation and the recognition of local traditions and minority rights. The principle of uti possidetis iuris was applied in order to prevent redrawing of the borders of new states and to maintain the territorial stability of the regions. But the recent migration crisis and security concerns in Europe and America have re-actualised the perception of state borders as defensive structures. Moreover, introduction of new technologies, such as ICT and the

  15. "Long life" DC brush motor for use on the Mars surveyor program

    Science.gov (United States)

    Braun, David; Noon, Don

    1998-01-01

    DC brush motors have several qualities which make them very attractive for space flight applications. Their mechanical commutation is simple and lightweight, requiring no external sensing and control in order to function properly. They are extremely efficient in converting electrical energy into mechanical energy. Efficiencies over 80% are not uncommon, resulting in high power throughput to weight ratios. However, the inherent unreliability and short life of sliding electrical contacts, especially in vacuum, have driven previous programs to utilize complex brushless DC or the less efficient stepper motors. The Mars Surveyor Program (MSP'98) and the Shuttle Radar Topography Mission (SRTM) have developed a reliable "long life" brush type DC motor for operation in low temperature, low pressure CO2 and N2, utilizing silver-graphite brushes. The original intent was to utilize this same motor for SRTM's space operation, but the results thus far have been unsatisfactory in vacuum. This paper describes the design, test, and results of this development.

  16. Hydrogel brushes grafted from stainless steel via surface-initiated atom transfer radical polymerization for marine antifouling

    Science.gov (United States)

    Wang, Jingjing; Wei, Jun

    2016-09-01

    Crosslinked hydrogel brushes were grafted from stainless steel (SS) surfaces for marine antifouling. The brushes were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) of 2-methacryloyloxyethyl phosphorylcholine (MPC) and poly(ethylene glycol) methyl ether methacrylate (PEGMA) respectively with different fractions of crosslinker in the feed. The grafted layers prepared with different thickness were characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), ellipsometry and water contact angle measurements. With the increase in the fraction of crosslinker in the feed, the thickness of the grafted layer increased and the surface became smooth. All the brush-coated SS surfaces could effectively reduce the adhesion of bacteria and microalgae and settlement of barnacle cyprids, as compared to the pristine SS surface. The antifouling efficacy of the PEGMA polymer (PPEGMA)-grafted surface was higher than that of the MPC polymer (PMPC)-grafted surfaces. Furthermore, the crosslinked hydrogel brush-grafted surfaces exhibited better fouling resistance than the non-crosslinked polymer brush-grafted surfaces, and the antifouling efficacy increased with the crosslinking density. These hydrogel coatings of low toxicity and excellent anti-adhesive characteristics suggested their useful applications as environmentally friendly antifouling coatings.

  17. Brushes and picks used on nails during the surgical scrub to reduce bacteria: a randomised trial.

    Science.gov (United States)

    Tanner, J; Khan, D; Walsh, S; Chernova, J; Lamont, S; Laurent, T

    2009-03-01

    Though brushes are no longer used on the hands and forearms during the surgical scrub, they are still widely used on the nails. The aim of this study was to determine whether nail picks and nail brushes are effective in providing additional decontamination during a surgical hand scrub. A total of 164 operating department staff were randomised to undertake one of the following three surgical hand-scrub protocols: chlorhexidine only; chlorhexidine and a nail pick; or chlorhexidine and a nail brush. Bacterial hand sampling was conducted before and 1h after scrubbing using a modified version of the glove juice method. No statistically significant differences in bacterial numbers were found between any two of the three intervention groups. Nail brushes and nail picks used during surgical hand scrubs do not decrease bacterial numbers and are unnecessary.

  18. Business, brokers and borders

    DEFF Research Database (Denmark)

    Walther, Olivier

    Using social network analysis, this paper studies the structure of trade networks that developed across West African borders. The first part aims to understand the centralization of cross-border trade networks. In a business environment where transaction costs are extremely high, we find...... developed with foreign partners from a different origin, religion or culture. In the second part, we study the spatial structure of trade networks and the influence of national borders on the development of social ties. The paper shows that the spatial form of trade networks is constrained by the historical...... origin of the traders engaged in cross-border activities. In those markets where trade is recent and where most of the traders are not native of the region, national borders are likely to exert a greater influence than in those regions where trade has pre-colonial roots....

  19. Clickable antifouling polymer brushes for polymer pen lithography

    Czech Academy of Sciences Publication Activity Database

    Bog, U.; de los Santos Pereira, Andres; Mueller, S. L.; Havenridge, S.; Parrillo, Viviana; Bruns, M.; Holmes, A. E.; Rodriguez-Emmenegger, C.; Fuchs, H.; Hirtz, M.

    2017-01-01

    Roč. 9, č. 13 (2017), s. 12109-12117 ISSN 1944-8244 R&D Projects: GA ČR(CZ) GJ15-09368Y Institutional support: RVO:61389013 Keywords : antifouling * biofunctional interfaces * polymer brushes Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 7.504, year: 2016

  20. Male brush-turkeys attempt sexual coercion in unusual circumstances.

    Science.gov (United States)

    Wells, David A; Jones, Darryl N; Bulger, David; Brown, Culum

    2014-07-01

    Sexual coercion by males is generally understood to have three forms: forced copulation, harassment and intimidation. We studied Australian brush-turkeys, Alectura lathami, to determine whether some male behaviours towards females at incubation mounds could be classified as aggressive, whether males were attempting sexual coercion and, if so, whether the coercion was successful. We found that some male behaviours towards females were significantly more likely to be followed by the cessation of female mound activity, and hence could be classified as aggressive, while others were significantly more likely to be followed by the commencement of female mound activity, and hence could be classified as enticing. Copulation was preceded by higher rates of male enticement and by higher rates of certain types of male aggression. It therefore seemed that males were attempting sexual coercion. There was little evidence, however, that this combination of coercion and enticement was successful in obtaining copulations. While forced copulation did occur, it was infrequent, and no evidence could be found for intimidation. We conclude that harassment is the primary form of sexual coercion by male brush-turkeys. Although sexual coercion is understood to be a sub-optimal tactic, brush-turkey sexual coercion was employed as a primary tactic by dominant males who owned incubation mounds. One possible explanation for this apparent paradox is that aggression is the default solution for social conflicts in this species, and hence can be interpreted as a behavioural syndrome. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Technology of high-speed combined machining with brush electrode

    Science.gov (United States)

    Kirillov, O. N.; Smolentsev, V. P.; Yukhnevich, S. S.

    2018-03-01

    The new method was proposed for high-precision dimensional machining with a brush electrode when the true position of bundles of metal wire is adjusted by means of creating controlled centrifugal forces appeared due to the increased frequency of rotation of a tool. There are the ultimate values of circumferential velocity at which the bundles are pressed against a machined area of a workpiece in a stable manner despite the profile of the machined surface and variable stock of the workpiece. The special aspects of design of processing procedures for finishing standard parts, including components of products with low rigidity, are disclosed. The methodology of calculation and selection of processing modes which allow one to produce high-precision details and to provide corresponding surface roughness required to perform finishing operations (including the preparation of a surface for metal deposition) is presented. The production experience concerned with the use of high-speed combined machining with an unshaped tool electrode in knowledge-intensive branches of the machine-building industry for different types of production is analyzed. It is shown that the implementation of high-speed dimensional machining with an unshaped brush electrode allows one to expand the field of use of the considered process due to the application of a multipurpose tool in the form of a metal brush, as well as to obtain stable results of finishing and to provide the opportunities for long-term operation of the equipment without its changeover and readjustment.

  2. Methylation analysis of CMTM3 and DUSP1 gene promoters in high-quality brush hair in the Yangtze River delta white goat.

    Science.gov (United States)

    Qiang, Wang; Guo, Haiyan; Li, Yongjun; Shi, Jianfei; Yin, Xiuyuan; Qu, Jingwen

    2018-08-20

    The Yangtze River delta white goat is the only goat breed that produces high-quality brush hair, which is specifically used in top-grade writing brushes. Previous studies have indicated that the CMTM3 and DUSP1 genes are involved in the growth and cycle of high-quality brush hair, and these genes are thought to be involved in the formation of high-quality brush hair traits. In this study, we investigated the relationship between methylation of CMTM3 and DUSP1 and such traits. The results indicated that the relative expression levels of the CMTM3 and DUSP1 genes were higher in non-high-quality brush hair than in high-quality brush hair. Furthermore, the CpG sites of the DUSP1 gene were not methylated, and the methylation level of CMTM3 was negatively correlated with the gene expression level. We believe that the DUSP1 gene regulates the formation of high-quality brush hair by non-methylated, and that methylation of the CMTM3 gene results in a decrease in its expression, causing an increase in the activity of the androgen receptor and the level of androgen. This high androgen level promotes the growth of high-quality brush hair. These study results provide a theoretical basis for further elucidating the molecular mechanism of the formation of high-quality brush hair characteristics, and provide scientific reference for the molecular breeding of high-quality brush hair. Copyright © 2018 Elsevier B.V. All rights reserved.

  3. Border Security: Barriers Along the U.S. International Border

    Science.gov (United States)

    2009-03-16

    1980). 120 Mexican Government Press Release, “Crecimiento con Calidad: El Presidente Vicente Fox encabezará la cena de gala de la XI Cumbre Anual...and Roads at Various Project Areas Located in California, Arizona, New Mexico , and Texas...Diego Border Primary Fence The USBP’s San Diego sector extends along the first 66 miles from the Pacific Ocean of the international border with Mexico

  4. Tooth brushing, tongue cleaning and snacking behaviour of dental ...

    African Journals Online (AJOL)

    2010-08-12

    Aug 12, 2010 ... frequency, duration and technique of tooth brushing and tongue cleaning as well as information on ... All the students in Year 1Б4 were included in the study. .... agents which are beneficial for prevention and treatment.

  5. Cross-border policy effects on alcohol outcomes: drinking without thinking on the u.s.-Mexico border?

    Science.gov (United States)

    Mills, Britain A; Caetano, Raul; Vaeth, Patrice

    2014-11-01

    Rates of alcohol-related outcomes are sensitive to policy differences in politically distinct, adjacent territories. Factors that shape these cross-border effects, particularly when the policy differences are longstanding, remain poorly understood. We compared the ability of 2 classes of variables with theoretical relevance to the U.S.-Mexico border context-bar attendance and alcohol-related social-cognitive variables-to explain elevated drinking on the U.S. side of the border relative to other areas of the United States. Data were collected from multistage cluster samples of adult Mexican Americans on and off the U.S.-Mexico border (current drinker N = 1,351). Structural equation models were used to test drinking context (frequency of bar attendance) and 6 different social-cognitive variables (including alcohol-related attitudes, norms, motives, and beliefs) as mediators of border effects on a composite drinking index. The border effect on drinking varied by age (with younger adults showing a stronger effect), consistent with previous findings and known risk factors in the region. Contrary to theoretical expectations, 6 different social-cognitive variables-despite relating strongly with drinking-were comparable in border and nonborder areas (within and across age) and played no role in elevated drinking on the border. Conversely, elevated drinking among border youth was mediated by bar attendance. This mediated moderation effect held after adjusting for potential sociodemographic and neighborhood-level confounders. Increased drinking among U.S.-Mexico border youth is explained by patterns of bar attendance, but not by more permissive alcohol-related social-cognitive variables in border areas: Border youth attend bars and drink more than their nonborder counterparts, despite having comparable alcohol-related beliefs, attitudes, norms, and motives for use. Alcohol's heightened availability and visibility on both sides of the border may create opportunities for

  6. [Surface roughness and gloss of novel flowable composites after polishing and simulated brushing wear].

    Science.gov (United States)

    Wang, R L; Yuan, C Y; Pan, Y X; Tian, F C; Wang, Z H; Wang, X Y

    2017-04-09

    Objective: To investigate surface properties of novel flowable composites after polishing and simulated brushing wear, compared to their pasty counterpart. Methods: Composites employed in this study were: three flowable composites (A1: Clearfil Majesty ES Flow; B1: Beautifil Flow Plus F00; C1: Filtek Bulk Fill) and three paste composites (A2: Clearfil Majesty; B2: Beautifil; C2: Filtek Z350. Eleven disk-shaped specimens were made for each material. The specimens were cured, then subjected to sandpaper finishing for 20 s, one-step polishing for 30 s, finally subjected to simulated brushing for 10 000 cycles. Surface roughness and glossiness were measured before finishing, after finishing, after polishing, after 5 000 brushing cycles and after 10 000 brushing cycles, respectively. Data obtained were analyzed using two-way ANOVA method. Scanning electron microscope was employed to examine the microscopic appearance of each material. Results: Surface roughness (0.11~0.22 μm) and glossiness (74.25~86.48 GU) of each material were similar after one-step polishing. After brushing simulation, roughness increased significantly and glossiness decreased significantly for each material ( Pgloss ([50.68±1.58] GU) after final wear ( P< 0.05). Flowable composites of group A1 and B1 tested in the present setup showed better surface properties compared to their pasty counterpart (group A2 and B2). Conclusions: Within the limit of this study, flowable composites tested in the present research can obtain similar surface polish or even better than the paste composite counterpart.

  7. Thermo-responsive and fluorescent cellulose nanocrystals grafted with polymer brushes

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Weibing [Nanjing Forestry Univ. (China); Georgia Inst. of Technology, Atlanta, GA (United States); Huang, Fang [Georgia Inst. of Technology, Atlanta, GA (United States); Pan, Shaobo [Georgia Inst. of Technology, Atlanta, GA (United States); Mu, Wei [Georgia Inst. of Technology, Atlanta, GA (United States); Meng, Xianzhi [Georgia Inst. of Technology, Atlanta, GA (United States); Yang, Haitao [Hubei Univ. of Technology, Wuhan (China); Xu, Zhaoyang [Nanjing Forestry Univ. (China); Ragauskas, Arthur J. [Georgia Inst. of Technology, Atlanta, GA (United States); Deng, Yulin [Georgia Inst. of Technology, Atlanta, GA (United States)

    2014-11-24

    Fluorescent and thermo-responsive cellulose nanocrystals (CNCs) with tuned polymer brushes were preparedviasurface initiated activators generated by electron transfer for atom transfer radical polymerization.

  8. Opportunities for Cross-Border Entrepreneurship Development in a Cluster Model Exemplified by the Polish–Czech Border Region

    Directory of Open Access Journals (Sweden)

    Joanna Kurowska-Pysz

    2016-03-01

    Full Text Available The subject of the paper is the analysis and evaluation of cross-border entrepreneurship development opportunities on the basis of cross-border cooperation, which has gradually evolved from consisting of bilateral partnerships to a networking model or even a cluster. The study conducted at the Polish–Czech border area indicates that, in terms of the development of cross-border cooperation, the economic sphere is lagging far behind social activities such as culture, education and tourism. At the same time, Polish and Czech enterprises are not sufficiently mobilized to develop cross-border entrepreneurship, although a number of support instruments in this regard have been proposed. Sustainable development of the border should take into account both social and economic aspects. An important research problem therefore becomes determining the possibility of boosting the development of cross-border entrepreneurship on the basis of the existing forms of cross-border cooperation, including cooperation in the social sphere. The aim of this paper is to define the conditions and opportunities for the development of cluster cooperation in the area of cross-border entrepreneurship. The author has attempted to resolve whether the intensity of cross-border cooperation can be a factor which mobilizes companies to develop their cross-border entrepreneurship and whether cross-border entrepreneurship can be further developed within the cluster model.

  9. Improved curvature-based inpainting applied to fine art: recovering van Gogh's partially hidden brush strokes

    Science.gov (United States)

    Kuang, Yubin; Stork, David G.; Kahl, Fredrik

    2011-03-01

    Underdrawings and pentimenti-typically revealed through x-ray imaging and infrared reflectography-comprise important evidence about the intermediate states of an artwork and thus the working methods of its creator.1 To this end, Shahram, Stork and Donoho introduced the De-pict algorithm, which recovers layers of brush strokes in paintings with open brush work where several layers are partially visible, such as in van Gogh's Self portrait with a grey felt hat.2 While that preliminary work served as a proof of concept that computer image analytic methods could recover some occluded brush strokes, the work needed further refinement before it could be a tool for art scholars. Our current work makes several steps to improve that algorithm. Specifically, we refine the inpainting step through the inclusion of curvature-based constraints, in which a mathematical curvature penalty biases the reconstruction toward matching the artist's smooth hand motion. We refine and test our methods using "ground truth" image data: passages of four layers of brush strokes in which the intermediate layers were recorded photographically. At each successive top layer (currently identified by the user), we used k-means clustering combined with graph cuts to obtain chromatically and spatially coherent segmentation of brush strokes. We then reconstructed strokes at the deeper layer with our new curvature-based inpainting algorithm based on chromatic level lines. Our methods are clearly superior to previous versions of the De-pict algorithm on van Gogh's works giving smoother, natural strokes that more closely match the shapes of unoccluded strokes. Our improved method might be applied to the classic drip paintings of Jackson Pollock, where the drip work is more open and the physics of splashing paint ensures that the curvature more uniform than in the brush strokes of van Gogh.

  10. Spontaneous transfer of stearic acids between human serum albumin and PEG:2000-grafted DPPC membranes.

    Science.gov (United States)

    Pantusa, Manuela; Stirpe, Andrea; Sportelli, Luigi; Bartucci, Rosa

    2010-05-01

    Electron spin resonance (ESR) spectroscopy is used to study the transfer of stearic acids between human serum albumin (HSA) and sterically stabilized liposomes (SSL) composed of dipalmitoylphosphatidylcholine (DPPC) and of submicellar content of poly(ethylene glycol:2000)-dipalmitoylphosphatidylethanolamine (PEG:2000-DPPE). Protein/lipid dispersions are considered in which spin-labelled stearic acids at the 16th carbon atom along the acyl chain (16-SASL) are inserted either in the protein or in the SSL. Two component ESR spectra with different rotational mobility are obtained over a broad range of temperature and membrane composition. Indeed, superimposed to an anisotropic protein-signal, appears a more isotropic lipid-signal. Since in the samples only one matrix (protein or membranes) is spin-labelled, the other component accounts for the transfer of 16-SASL between albumin and membranes. The two components have been resolved and quantified by spectral subtractions, and the fraction, f (p) (16-SASL), of spin labels bound non-covalently to the protein has been used to monitor the transfer. It is found that it depends on the type of donor and acceptor matrix, on the physical state of the membranes and on the grafting density of the polymer-lipids. Indeed, it is favoured from SSL to HSA and the fraction of stearic acids transferred increases with temperature in both directions of transfer. Moreover, in the presence of polymer-lipids, the transfer from HSA to SSL is slightly attenuated, especially in the brush regime of the polymer-chains. Instead, the transfer from SSL to HSA is favoured by the polymer-lipids much more in the mushroom than in the brush regime.

  11. Profilometric analysis of two composite resins' surface repolished after tooth brush abrasion with three polishing systems.

    Science.gov (United States)

    Uppal, Mudit; Ganesh, Arathi; Balagopal, Suresh; Kaur, Gurleen

    2013-07-01

    To evaluate the effect of three polishing protocols that could be implemented at recall on the surface roughness of two direct esthetic restorative materials. Specimens (n = 40) measuring 8 mm (length) × 5 mm (width) × 4 mm (height) were fabricated in an acrylic mold using two light-cured resin-based materials (microfilled composite and microhybrid composite). After photopolymerization, all specimens were finished and polished with one of three polishing protocols (Enhance, One Gloss, and Sof-Lex polishing systems). The average surface roughness of each treated specimen was determined using 3D optical profilometer. Next all specimens were brushed 60,000 times with nylon bristles at 7200 rpm using crosshead brushing device with equal parts of toothpaste and water used as abrasive medium. The surface roughness of each specimen was measured after brushing followed by repolishing with one of three polishing protocols, and then, the final surface roughness values were determined. The data were analyzed using one-way and two-factor analysis of variance (ANOVA) and Tukey's honestly significant difference (HSD). Significant difference (P < 0.05) in surface roughness was observed. Simulated brushing following initial polishing procedure significantly roughened the surface of restorative material (P < 0.05). Polishing protocols can be used to restore a smooth surface on esthetic restorative materials following simulated tooth brushing.

  12. Border patrol: insights into the unique role of perlecan/heparan sulfate proteoglycan 2 at cell and tissue borders.

    Science.gov (United States)

    Farach-Carson, Mary C; Warren, Curtis R; Harrington, Daniel A; Carson, Daniel D

    2014-02-01

    The extracellular matrix proteoglycan (ECM) perlecan, also known as heparan sulfate proteoglycan 2 or HSPG2, is one of the largest (>200 nm) and oldest (>550 M years) extracellular matrix molecules. In vertebrates, perlecan's five-domain structure contains numerous independently folding modules with sequence similarities to other ECM proteins, all connected like cars into one long, diverse complex train following a unique N-terminal domain I decorated with three long glycosaminoglycan chains, and an additional glycosaminoglycan attachment site in the C-terminal domain V. In lower invertebrates, perlecan is not typically a proteoglycan, possessing the majority of the core protein modules, but lacking domain I where the attachment sites for glycosaminoglycan chains are located. This suggests that uniting the heparan sulfate binding growth factor functions of domain I and the core protein functions of the rest of the molecule in domains II-V occurred later in evolution for a new functional purpose. In this review, we surveyed several decades of pertinent literature to ask a fundamental question: Why did nature design this protein uniquely as an extraordinarily long multifunctional proteoglycan with a single promoter regulating expression, rather than separating these functions into individual proteins that could be independently regulated? We arrived at the conclusion that the concentration of perlecan at functional borders separating tissues and tissue layers is an ancient key function of the core protein. The addition of the heparan sulfate chains in domain I likely occurred as an additional means of binding the core protein to other ECM proteins in territorial matrices and basement membranes, and as a means to reserve growth factors in an on-site depot to assist with rapid repair of those borders when compromised, such as would occur during wounding. We propose a function for perlecan that extends its role from that of an extracellular scaffold, as we previously

  13. Securing the Borders: Creation of the Border Patrol Auxiliary

    Science.gov (United States)

    2007-05-05

    DATES COVERED 00-00-2007 to 00-00-2007 4. TITLE AND SUBTITLE Securing the Borders: Creation of the Border Patrol Auxillary 5a. CONTRACT NUMBER...Substantial work experience which demonstrates an ability to (1) take charge, make sound decisions , and maintain composure in stressful situations; (2...applicable laws, court decisions , and law enforcement procedures; and 4. Develop and maintain contact with the network of informants. ¾ To qualify at

  14. "Nonclassical" secretion of annexin A2 to the lumenal side of the enterocyte brush border membrane

    DEFF Research Database (Denmark)

    Danielsen, E Michael; van Deurs, Bo; Hansen, Gert H

    2003-01-01

    side of the microvilli, showing an apical secretion by a "nonclassical" mechanism. In addition, annexin A2 was associated with surface-connected, deep apical tubules in the apical terminal web region and with an underlying pleiomorphic, tubulo-vesicular compartment (subapical compartment...

  15. Phototriggered functionalization of hierarchically structured polymer brushes

    Czech Academy of Sciences Publication Activity Database

    de los Santos Pereira, Andres; Kostina, Nina Yu.; Bruns, M.; Rodriguez-Emmenegger, Cesar; Barner-Kowollik, C.

    2015-01-01

    Roč. 31, č. 21 (2015), s. 5899-5907 ISSN 0743-7463 R&D Projects: GA ČR(CZ) GJ15-09368Y; GA MŠk(CZ) ED1.1.00/02.0109 Grant - others:OPPK(XE) CZ.2.16/3.1.00/21545 Program:OPPK Institutional support: RVO:61389013 Keywords : polymer brushes * antifouling * click chemistry Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.993, year: 2015

  16. Antifouling polymer brushes displaying antithrombogenic surface properties

    Czech Academy of Sciences Publication Activity Database

    de los Santos Pereira, Andres; Sheikh, S.; Blaszykowski, C.; Pop-Georgievski, Ognen; Fedorov, K.; Thompson, M.; Rodriguez-Emmenegger, Cesar

    2016-01-01

    Roč. 17, č. 3 (2016), s. 1179-1185 ISSN 1525-7797 R&D Projects: GA ČR(CZ) GJ15-09368Y; GA MŠk(CZ) ED1.1.00/02.0109 Grant - others:OPPK(XE) CZ.2.16/3.1.00/21545 Program:OPPK Institutional support: RVO:61389013 Keywords : polymer brushes * surface characterization * antifouling surfaces Subject RIV: BO - Biophysics Impact factor: 5.246, year: 2016

  17. Co-adhesion and removal of adhering bacteria from salivary pellicles by three different modes of brushing

    NARCIS (Netherlands)

    Yang, J; Belder, GF; Busscher, HJ; Bos, R.R.M.

    2001-01-01

    This study compares removal of pairs of co-adhering and non-co-adhering oral actinomyces and streptococci by hand, electric and sonic brushing from salivary pellicles. In addition, re-deposition of a co-adhering and non-co-adhering streptococcal strain to brushed pellicles was studied. First,

  18. Why Border Enforcement Backfired.

    Science.gov (United States)

    Massey, Douglas S; Durand, Jorge; Pren, Karen A

    2016-03-01

    In this article we undertake a systematic analysis of why border enforcement backfired as a strategy of immigration control in the United States. We argue theoretically that border enforcement emerged as a policy response to a moral panic about the perceived threat of Latino immigration to the United States propounded by self-interested bureaucrats, politicians, and pundits who sought to mobilize political and material resources for their own benefit. The end result was a self-perpetuating cycle of rising enforcement and increased apprehensions that resulted in the militarization of the border in a way that was disconnected from the actual size of the undocumented flow. Using an instrumental variable approach, we show how border militarization affected the behavior of unauthorized migrants and border outcomes to transform undocumented Mexican migration from a circular flow of male workers going to three states into an eleven-million person population of settled families living in 50 states.

  19. Production rates for United States Forest Service brush disposal planning in the northern Rocky Mountains

    Science.gov (United States)

    Dan Loeffler; Stu Hoyt; Nathaniel Anderson

    2017-01-01

    Timber harvesting operations generate brush and other vegetative debris, which often has no marketable value. In many western U.S. forests, these materials represent a fire hazard and a potential threat to forest health and must be removed or burned for disposal. Currently, there is no established, consistent method to estimate brush disposal production rates in the U....

  20. Cytology evaluation for brushing in biliary and pancreatic stenosis during endoscopic cholangiopancreatography

    International Nuclear Information System (INIS)

    Ruiz, Mario H; Castano, Rodrigo; Alvarez, Oscar A; Velez, Alejandro; Munera, Veronica

    2002-01-01

    No surgical pathologic confirmation of malignant bile duct strictures is desirable for defining subsequent treatment and prognosis. Endoscopic retrograde cholangiopancreatography is frequently performed in patients suspected of having pancreaticobiliary obstruction, but there exists no standardized method or instruments for defining benign or malignant nature of obstructing lesions by ERCP. We prospectively evaluated the yields of endoscopic retrograde brush cytology for the diagnosis of malignant bile and pancreatic duct strictures. Fluoroscopically guided endobiliary brush cytology was performed during endoscopic retrograde cholangiopancreatography in 29 consecutive patients, 20 with malignant strictures and 9 with benign stricture. A single pathologist classified the results of these studies as positive, or negative for malignancy. The sensitivities of the procedure were 69%. Specificity proved excellent, 100%. Two major complications that occurred in the same patient were acute pancreatitis in a patient with chronic pancreatitis and bleeding from pancreatic duct. Both were managed medically and improved. This study indicates that endoscopic retrograde brush cytology alone may be sufficient in daily practice, to differentiate against benign and malignant biliary or pancreatic stenosis

  1. Organic monolayers and fluoropolymer brushes : functionalization, stability and tribology

    NARCIS (Netherlands)

    Bhairamadgi, N.S.

    2014-01-01

    This thesis deals with the adhesion and friction properties of densely grafted and covalently bound fluoropolymer brushes on silicon surfaces with varying thickness and fluorine content. A novel surface-functionalizing method is described using the thiol-yne click (TYC) reaction. The TYC

  2. International Issues, High-Stakes Testing, and Border Pedagogy: Social Studies at Border High School

    Science.gov (United States)

    Cashman, Timothy G.; McDermott, Benjamin R.

    2013-01-01

    A recently constructed border wall stands within walking distance of Border High School (BHS) and was created to impede the flow of people, goods, fauna, and contraband from Mexico into the United States (U.S.). The reality, however, is that this geopolitical border is fluid, allowing connections between sociopolitical zones. The researchers…

  3. Cross-border shopping and tourism destination marketing

    DEFF Research Database (Denmark)

    Makkonen, Teemu

    2016-01-01

    This article addresses the economic impact that cross-border shopping has on the local tourism industry and the ways that cross-border shopping is taken advantage of in tourism destination marketing. Southern Jutland–situated in Denmark just north of the German border, where border shops situated......-border shopping into tourism destination marketing strategies. The results have wider relevance for other border regions.......This article addresses the economic impact that cross-border shopping has on the local tourism industry and the ways that cross-border shopping is taken advantage of in tourism destination marketing. Southern Jutland–situated in Denmark just north of the German border, where border shops situated...... just south of the same border enable Danes to capitalize on the lower value added tax levels in Germany–is utilized as an illustrative case example. The data was collected by analysing the relevant tourism destination marketing material and via interviews with local destination marketing organizations...

  4. Border mythology: Turner and modernity

    Directory of Open Access Journals (Sweden)

    Jorge E. Brenna B.

    2011-07-01

    Full Text Available Modernity has been creating spaces, new boundaries and borders, as metaphysical, mythological and symbolic marks of physical and imaginary territories. Modern space and its borders are metaphors, boundaries that are created, walls that rise to identify with some and categorize others. In this short paper we want to approach the problem of the transformation of the idea of border (geographical, cultural, symbolic, etc., for a reflection on the transformations of that civilized obsession called border. The border has always been a reference in facing the identities, names, symbols, different imaginary: it is more confrontational line between two otherness. From the previous framework, we reflect on Turnerian mythology, as we believe that behind the creation of the imagination of the northern border is the mythical vision of the American frontier as ideological canon that explains and confirms the presence of the white race in a border re–made in the image and likeness of the “American Dream”. Frederick Turner’s reflection on the role of the frontier in American history is not only the study of the importance of progress towards the West but –even more so, is the analysis of meaning that had the American frontier as a historical process that ended in 1893, as Turner said, but rather extended into the twentieth century and continues to constantly shaping the process of territorialization of the border.

  5. Border trees of complex networks

    International Nuclear Information System (INIS)

    Villas Boas, Paulino R; Rodrigues, Francisco A; Travieso, Gonzalo; Fontoura Costa, Luciano da

    2008-01-01

    The comprehensive characterization of the structure of complex networks is essential to understand the dynamical processes which guide their evolution. The discovery of the scale-free distribution and the small-world properties of real networks were fundamental to stimulate more realistic models and to understand important dynamical processes related to network growth. However, the properties of the network borders (nodes with degree equal to 1), one of its most fragile parts, remained little investigated and understood. The border nodes may be involved in the evolution of structures such as geographical networks. Here we analyze the border trees of complex networks, which are defined as the subgraphs without cycles connected to the remainder of the network (containing cycles) and terminating into border nodes. In addition to describing an algorithm for identification of such tree subgraphs, we also consider how their topological properties can be quantified in terms of their depth and number of leaves. We investigate the properties of border trees for several theoretical models as well as real-world networks. Among the obtained results, we found that more than half of the nodes of some real-world networks belong to the border trees. A power-law with cut-off was observed for the distribution of the depth and number of leaves of the border trees. An analysis of the local role of the nodes in the border trees was also performed

  6. Preparation of polystyrene brush film by radical chain-transfer polymerization and micromechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Jing [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Chen Miao [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)], E-mail: miaochen99@yahoo.com; An Yanqing [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Liu Jianxi [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Yan Fengyuan [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)], E-mail: fyyan@lzb.ac.cn

    2008-12-30

    A radical chain-transfer polymerization technique has been applied to graft-polymerize brushes of polystyrene (PSt) on single-crystal silicon substrates. 3-Mercapto-propyltrimethoxysilane (MPTMS), as a chain-transfer agent for grafting, was immobilized on the silicon surface by a self-assembling process. The structure and morphology of the graft-functionalized silicon surfaces were characterized by the means of contact-angle measurement, ellipsometric thickness measurement, Fourier transformation infrared (FTIR) spectroscopy, and atomic force microscopy (AFM). The nanotribological and micromechanical properties of the as-prepared polymer brush films were investigated by frictional force microscopy (FFM), force-volume analysis and scratch test. The results indicate that the friction properties of the grafted polymer films can be improved significantly by the treatment of toluene, and the chemically bonded polystyrene film exhibits superior scratch resistance behavior compared with the spin-coated polystyrene film. The resultant polystyrene brush film is expected to develop as a potential lubrication coating for microelectromechanical systems (MEMS)

  7. Hmong Across Borders or Borders Across Hmong? Social and Political Influences Upon Hmong People

    Directory of Open Access Journals (Sweden)

    Prasit Leepreecha

    2014-12-01

    Full Text Available The Hmong are a transnational ethnic people, because of their dispersal from China into Southeast Asia in the early 19th century and from Southeast Asia to Western countries from 1975 onward. However, even within the context of Southeast Asia and southern China, the Hmong are a transnational ethnic group, due to state boundaries and the enforcement of international laws.Scholars speak as though the Hmong population has crossed political and legal borders by their movement across state boundaries and international borders. However, I argue that it is the political, social, and legal borders that have cut across the Hmong people and subjected them to be citizens of different modern nation-states. Even in the present time, these borders still, and continuously, play important roles that cross and divide the Hmong people into distinctive subgroups and fragments. In this article, I will start by describing the generally understood situation of Hmong being across national borders, and then will explain my argument that borders are across the Hmong.

  8. The Migrant Border Crossing Study: A methodological overview of research along the Sonora-Arizona border.

    Science.gov (United States)

    Martínez, Daniel E; Slack, Jeremy; Beyerlein, Kraig; Vandervoet, Prescott; Klingman, Kristin; Molina, Paola; Manning, Shiras; Burham, Melissa; Walzak, Kylie; Valencia, Kristen; Gamboa, Lorenzo

    2017-07-01

    Increased border enforcement efforts have redistributed unauthorized Mexican migration to the United States (US) away from traditional points of crossing, such as San Diego and El Paso, and into more remote areas along the US-Mexico border, including southern Arizona. Yet relatively little quantitative scholarly work exists examining Mexican migrants' crossing, apprehension, and repatriation experiences in southern Arizona. We contend that if scholars truly want to understand the experiences of unauthorized migrants in transit, such migrants should be interviewed either at the border after being removed from the US, or during their trajectories across the border, or both. This paper provides a methodological overview of the Migrant Border Crossing Study (MBCS), a unique data source on Mexican migrants who attempted an unauthorized crossing along the Sonora-Arizona border, were apprehended, and repatriated to Nogales, Sonora in 2007-09. We also discuss substantive and theoretical contributions of the MBCS.

  9. Straddling the border

    DEFF Research Database (Denmark)

    Eilenberg, Michael

    2011-01-01

    border between the Indonesian province of West Kalimantan and the Malaysian state of Sarawak on the island of Borneo. Based on local narratives, the aim of this paper is to unravel the little known history of how the Iban segment of the border population in West Kalimantan became entangled in the highly...

  10. Preparing polymer brushes on polytetrafluoroethylene films by free radical polymerization

    International Nuclear Information System (INIS)

    Sun Wei; Chen Yiwang; Deng Qilan; Chen Lie; Zhou Lang

    2006-01-01

    Films of polytetrafluoroethylene (PTFE) were exposed to sodium naphthalenide (Na/naphtha) etchant so as to defluorinate the surface for obtaining hydroxyl functionality. Surface-initiators were immobilized on the PTFE films by esterification of 4,4'-azobis(4-cyanopentanoic acid) (ACP) and the hydroxyl groups covalently linked to the surface. Grafting of polymer brushes on the PTFE films was carried out by the surface-initiated free radical polymerization. Homopolymers brushes of methyl methacrylate (MMA) were prepared by free radical polymerization from the azo-functionalized PTFE surface. The chemical composition and topography of the graft-functionalized PTFE surfaces were characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance (ATR) FT-IR spectroscopy and atomic force microscopy (AFM). Water contact angles on PTFE films were reduced by surface grafting of MMA

  11. Tooth brushing, tongue cleaning and snacking behaviour of dental ...

    African Journals Online (AJOL)

    Objective: To determine the tooth brushing, tongue cleaning and snacking behaviour of dental technology and therapist students. Methods: A descriptive cross-sectional study of students of Federal School of Dental Therapy and Technology Enugu, Nigeria. Self-administered questionnaire was used to obtain information on ...

  12. Border Crossing/Entry Data

    Data.gov (United States)

    Department of Transportation — The dataset is known as “Border Crossing/Entry Data.” The Bureau of Transportation Statistics (BTS) Border Crossing/Entry Data provides summary statistics to the...

  13. Small Border Traffic and Cross-Border Tourism Between Poland and the Kaliningrad Oblast of the Russian Federation

    OpenAIRE

    Anisiewicz Renata; Palmowski Tadeusz

    2014-01-01

    Polish and Russian cross-border cooperation is governed by lawful agreements. The enlargement of the Schengen Area had a significant impact on Kaliningrad Oblast relations and cross-border cooperation with its neighbours. The introduction of visas between Poland and Russia hindered and restricted local border trade which had for years been the only measure mitigating social and economic problems of the cross-border regions. Nevertheless, border traffic between Poland and Kaliningrad grew stea...

  14. Molecular aggregation states of poly{2-(perfluorooctyl)ethyl acrylate} polymer brush thin film analyzed by grazing incidence X-ray diffraction

    International Nuclear Information System (INIS)

    Yamaguchi, H; Honda, K; Takahara, A; Kobayashi, M; Morita, M; Masunaga, H; Sasaki, S; Takata, M; Sakata, O

    2009-01-01

    Fluoropolymer brush with crystalline side chains was prepared by surface-initiated atom transfer radical polymerization of 2-(perfluorooctyl)ethyl acrylate (FA-C 8 ) from a flat silicon substrate. The crystallization and the molecular aggregation structures of polymer side chain at the outermost surface and internal region in the brush film were characterized by grazing incidence X-ray diffraction (GIXD) measurement using two different incident angles of X-ray. At the air interface of PFA-C 8 brush film, the rod-like R f group was oriented perpendicular to the surface forming a hexagonal packing structure to reduce surface energy. In contrast, the oriented R f groups parallel to the substrate coexisted at the internal region in the brush. This unique depth dependence of crystalline state of the fluoropolymer brush was observed by surface-sensitive GIXD measurement.

  15. Brush Seals for Cryogenic Applications: Performance, Stage Effects, and Preliminary Wear Results in LN2 and LH2

    Science.gov (United States)

    Proctor, Margaret P.; Walker, James F.; Perkins, H. Douglas; Hoopes, Joan F.; Williamson, G. Scott

    1996-01-01

    Brush seals are compliant contacting seals and have significantly lower leakage than labyrinth seals in gas turbine applications. Their long life and low leakage make them candidates for use in rocket engine turbopumps. Brush seals, 50.8 mm (2 in.) in diameter with a nominal 127-micron (0.005-in.) radial interference, were tested in liquid nitrogen (LN2) and liquid hydrogen (LH2) at shaft speeds up to 35,000 and 65,000 rpm, respectively, and at pressure drops up to 1.21 MPa (175 psid) per brush. A labyrinth seal was also tested in liquid nitrogen to provide a baseline. The LN2 leakage rate of a single brush seal with an initial radial shaft interference of 127 micron (0.005 in.) measured one-half to one-third the leakage rate of a 12-tooth labyrinth seal with a radial clearance of 127 micron (0.005 in.). Two brushes spaced 7.21 micron (0.248 in.) apart leaked about one-half as much as a single brush, and two brushes tightly packed together leaked about three-fourths as much as a single brush. The maximum measured groove depth on the Inconel 718 rotor with a surface finish of 0.81 micron (32 microinch) was 25 micron (0.0010 in.) after 4.3 hr of shaft rotation in liquid nitrogen. The Haynes-25 bristles wore approximately 25 to 76 micron (0.001 to 0.003 in.) under the same conditions. Wear results in liquid hydrogen were significantly different. In liquid hydrogen the rotor did not wear, but the bristle material transferred onto the rotor and the initial 127 micron (0.005 in.) radial interference was consumed. Relatively high leakage rates were measured in liquid hydrogen. More testing is required to verify the leakage performance, to validate and calibrate analysis techniques, and to determine the wear mechanisms. Performance, staging effects, and preliminary wear results are presented.

  16. Normally Oriented Adhesion versus Friction Forces in Bacterial Adhesion to Polymer-Brush Functionalized Surfaces Under Fluid Flow

    NARCIS (Netherlands)

    Swartjes, Jan J. T. M.; Veeregowda, Deepak H.; van der Mei, Henny C.; Busscher, Henk J.; Sharma, Prashant K.

    2014-01-01

    Bacterial adhesion is problematic in many diverse applications. Coatings of hydrophilic polymer chains in a brush configuration reduce bacterial adhesion by orders of magnitude, but not to zero. Here, the mechanism by which polymer-brush functionalized surfaces reduce bacterial adhesion from a

  17. Titanium surface topography after brushing with fluoride and fluoride-free toothpaste simulating 10 years of use.

    Science.gov (United States)

    Fais, Laiza M G; Fernandes-Filho, Romeu B; Pereira-da-Silva, Marcelo A; Vaz, Luis G; Adabo, Gelson L

    2012-04-01

    To conduct a controlled study contrasting titanium surface topography after procedures that simulated 10 years of brushing using toothpastes with or without fluoride. Commercially pure titanium (cp Ti) and Ti-6Al-4V disks (6 mm Ø×4 mm) were mirror-polished and treated according to 6 groups (n=6) as a function of immersion (I) or brushing (B) using deionised water (W), fluoride-free toothpaste (T) and fluoride toothpaste (FT). Surface topography was evaluated at baseline (pretreatment) and post-treatment, using atomic force microscope in order to obtain three-dimensional images and mean roughness. Specimens submitted to immersion were submerged in the vehicles without brushing. For brushed specimens, procedures were conducted using a linear brushing machine with a soft-bristled toothbrush. Immersion and brushing were performed for 244 h. IFT and BFT samples were analysed under scanning electron microscope with Energy-Dispersive X-ray Spectroscopy (EDS). Pre and post-treatment values were compared using the paired Student T-test (α=.05). Intergroup comparisons were conducted using one-way ANOVA with Tukey post-test (α=.05). cp Ti mean roughness (in nanometers) comparing pre and post-treatment were: IW, 2.29±0.55/2.33±0.17; IT, 2.24±0.46/2.02±0.38; IFT, 2.22±0.53/1.95±0.36; BW, 2.22±0.42/3.76±0.45; BT, 2.27±0.55/16.05±3.25; BFT, 2.27±0.51/22.39±5.07. Mean roughness (in nanometers) measured in Ti-6Al-4V disks (pre/post-treatment) were: IW, 1.79±0.25/2.01±0.25; IT, 1.61±0.13/1.74±0.19; IFT, 1.92±0.39/2.29±0.51; BW, 2.00±0.71/2.05±0.43; BT, 2.37±0.86/11.17±2.29; BFT, 1.83±0.50/15.73±1.78. No significant differences were seen after immersions (p>.05). Brushing increased the roughness of cp Ti and of Ti-6Al-4V (p<.01); cp Ti had topographic changes after BW, BT and BFT treatments whilst Ti-6Al-4V was significantly different only after BT and BTF. EDS has not detected fluoride or sodium ions on metal surfaces. Exposure to toothpastes (immersion

  18. Who’s Who at the Border? A rights-based approach to identifying human trafficking at international borders

    Directory of Open Access Journals (Sweden)

    Marika McAdam

    2013-09-01

    Full Text Available International borders are widely touted as bastions in the fight against trafficking in persons. This article acknowledges the important role border officials play in preventing human trafficking, but calls for expectations to be tempered by deference to the conceptual complexity of cross-border trafficking and the migration processes involved. The fact that many trafficked victims begin their journeys as irregular or smuggled migrants highlights the challenge posed to border officials in identifying trafficked persons among the people they encounter. Indicators of trafficking generally relate to the exploitation phase, leaving border officials with little guidance as to how persons vulnerable to trafficking can be accurately identified before any exploitation has occurred. Ultimately, this paper advocates a pragmatic rights-based approach in designating anti-trafficking functions to border officials. A rights-based approach to border control acknowledges the core work of border officials as being to uphold border integrity, while ensuring that their performance of this role does not jeopardise the rights of those they intercept nor result in missed opportunities for specialists to identify trafficked persons and other vulnerable people among them.

  19. Cylindrical polymer brushes with dendritic side chains by iterative anionic reactions

    KAUST Repository

    Zhang, Hefeng

    2015-05-01

    We report in this paper an easy method for the synthesis of cylindrical polymer brushes with dendritic side chains through anionic reaction. The synthesis is accomplished by iteratively grafting a living block copolymer, polyisoprene-. b-polystyrenyllithium (PI-. b-PSLi), to the main chain and subsequently to the branches in a divergent way. PI segment is short and serves as a precursor for multifunctional branching unit. The grafting reaction involves two successive steps: i) epoxidation of internal double bonds of PI segments, either in main chain or side chains; ii) ring-opening addition to the resulting epoxy group by the living PI-. b-PSLi. Repeating the two steps affords a series of cylindrical polymer brushes with up to 3rd generation and extremely high molecular weight. The branching multiplicity depends on the average number of oxirane groups per PI segment, usually ca. 8 in the present work. The high branching multiplicity leads to tremendous increase in molecular weights of the cylindrical products with generation growth. Several series of cylindrical polymer brushes with tunable aspect ratios are prepared using backbones and branches with controlled lengths. Shape anisotropy is investigated in dilute solution using light scattering technique. Worm-like single molecular morphology with large persistence length is observed on different substrates by atomic force microscopy.

  20. A Novel Method for Sensorless Speed Detection of Brushed DC Motors

    Directory of Open Access Journals (Sweden)

    Ernesto Vazquez-Sanchez

    2016-12-01

    Full Text Available Many motor applications require accurate speed measurement. For brushed dc motors, speed can be measured with conventional observers or sensorless observers. Sensorless observers have the advantage of not requiring any external devices to be attached to the motor. Instead, voltage and/or current are measured and used to estimate the speed. The sensorless observers are usually divided into two groups: those based on the dynamic model, and those based on the ripple component. This paper proposes a method that measures the current of brushed dc motors and analyses the position of its spectral components. From these spectral components, the method estimates the motor speed. Three tests, performed each with the speeds ranging from 2000 to 3000 rpm either at constant-speed, at slowly changing speeds, or at rapidly changing speeds, showed that the average error was below 1 rpm and that the deviation error was below 1.5 rpm. The proposed method: (i is a novel method that is not based on either the dynamic model or on the ripple component; (ii requires only the measurement of the current for the speed estimation; (iii can be used for brushed dc (direct current motors with a large number of coils; and (iv achieves a low error in the speed estimation.

  1. Small Border Traffic and Cross-Border Tourism Between Poland and the Kaliningrad Oblast of the Russian Federation

    Directory of Open Access Journals (Sweden)

    Anisiewicz Renata

    2014-06-01

    Full Text Available Polish and Russian cross-border cooperation is governed by lawful agreements. The enlargement of the Schengen Area had a significant impact on Kaliningrad Oblast relations and cross-border cooperation with its neighbours. The introduction of visas between Poland and Russia hindered and restricted local border trade which had for years been the only measure mitigating social and economic problems of the cross-border regions. Nevertheless, border traffic between Poland and Kaliningrad grew steadily, to exceed four million in 2012.

  2. Measuring cross-border travel times for freight : Otay Mesa international border crossing.

    Science.gov (United States)

    2010-09-01

    Cross border movement of people and goods is a vital part of the North American economy. Accurate real-time data on travel times along the US-Mexico border can help generate a range of tangible benefits covering improved operations and security, lowe...

  3. Cross-border innovation cooperation

    DEFF Research Database (Denmark)

    Hjaltadóttir, Rannveig Edda; Makkonen, Teemu; Sørensen, Nils Karl

    2017-01-01

    Finding a suitable partner is paramount for the success of innovation cooperation. Thus, this paper sets out to analyse the determinants of cross-border innovation cooperation in Denmark by focusing on partner selection. The aim of the article is to investigate determinants of partner selection...... by taking the location of the partners into account. In particular, the discussion is tied to the notion of varying knowledge bases firms utilize in their innovation creation processes. Firm level data from the 2010 Community Innovation Survey in Denmark was utilized to analyse cross-border innovation...... of innovativeness increase the likelihood of cross-border innovation cooperation. Accordingly, geographical proximity to international borders is found to have a significant, positive effect on selecting partners within the European Union. The multivariate probit model shows that the decision of choosing a domestic...

  4. Smart border initiative: a Franco-German cross-border energy optimisation project

    International Nuclear Information System (INIS)

    2017-01-01

    Integrated and optimised local energy systems will play a key role in achieving the energy transition objectives set by France and Germany, in line with the Energy Union's goals, and contribute to ensuring a secure, affordable and climate-friendly energy supply in the EU. In order to capitalise on the French and German expertise and experiences in developing such systems and to continue strengthening the cross-border cooperation towards a fully integrated European energy market, both Governments have decided to launch a common initiative to identify and structure a cross-border energy optimisation project. Tilia and Dena have undertaken this mission to jointly develop the Smart Border Initiative (SBI). The SBI will, on the one hand, connect policies designed by France and Germany in order to support their cities and territories in their energy transition strategies and European market integration. It is currently a paradox that, though more balanced and resilient energy systems build up, bottom-up, at the local level, borders remain an obstacle to this local integration, in spite of the numerous complementarities observed in cross-border regions, and of their specific needs, in terms of smart mobility for example. The SBI project aims at enabling European neighbouring regions separated by a border to jointly build up optimised local energy systems, and jointly develop their local economies following an integrated, sustainable and low-carbon model. On the other hand, this showcase project will initiate a new stage in the EU electricity market integration, by completing high voltage interconnections with local, low voltage integration at DSO level, opening new optimisation possibilities in managing the electricity balance, and enabling DSOs to jointly overcome some of the current challenges, notably the increased share of renewable energy (RE) and ensuring Europe's security of supply

  5. Border information flow architecture

    Science.gov (United States)

    2006-04-01

    This brochure describes the Border Information Flow Architecture (BIFA). The Transportation Border Working Group, a bi-national group that works to enhance coordination and planning between the United States and Canada, identified collaboration on th...

  6. Damage of target edges in brush-like geometry in the course of ELM-like plasma pulses in QSPA Kh-50

    Science.gov (United States)

    Makhlaj, V. A.; Garkusha, I. E.; Aksenov, N. N.; Bazylev, B.; Byrka, O. V.; Chebotarev, V. V.; Landman, I.; Herashchenko, S. S.; Staltsov, V. V.

    2015-08-01

    Castellated edges of macro-brush armour elements of ITER divertor can be a source of molten/solid dust particles which are injected into the plasma. The targets that combined in brush-like geometry have been irradiated under different inclination angles in QSPA Kh-50. The cubic brushes element has typical size of 1 cm. The titanium was used to investigate dynamics of mountains' formation. The onset of dust particles ejection from the exposed castellated targets has been studied. Formation of resolidified bridges through the gaps of brush-like targets due to the melt motion is studied in dynamics. With following plasma impacts such resolidified bridges became additional source of dust.

  7. Damage of target edges in brush-like geometry in the course of ELM-like plasma pulses in QSPA Kh-50

    International Nuclear Information System (INIS)

    Makhlaj, V.A.; Garkusha, I.E.; Aksenov, N.N.; Bazylev, B.; Byrka, O.V.; Chebotarev, V.V.; Landman, I.; Herashchenko, S.S.; Staltsov, V.V.

    2015-01-01

    Castellated edges of macro-brush armour elements of ITER divertor can be a source of molten/solid dust particles which are injected into the plasma. The targets that combined in brush-like geometry have been irradiated under different inclination angles in QSPA Kh-50. The cubic brushes element has typical size of 1 cm. The titanium was used to investigate dynamics of mountains’ formation. The onset of dust particles ejection from the exposed castellated targets has been studied. Formation of resolidified bridges through the gaps of brush-like targets due to the melt motion is studied in dynamics. With following plasma impacts such resolidified bridges became additional source of dust

  8. Damage of target edges in brush-like geometry in the course of ELM-like plasma pulses in QSPA Kh-50

    Energy Technology Data Exchange (ETDEWEB)

    Makhlaj, V.A., E-mail: makhlay@ipp.kharkov.ua [Institute of Plasma Physics of the NSC KIPT, 61108 Kharkov (Ukraine); Garkusha, I.E.; Aksenov, N.N. [Institute of Plasma Physics of the NSC KIPT, 61108 Kharkov (Ukraine); Bazylev, B. [Karlsruhe Institute of Technology (KIT), IHM, 76344 Karlsruhe (Germany); Byrka, O.V.; Chebotarev, V.V. [Institute of Plasma Physics of the NSC KIPT, 61108 Kharkov (Ukraine); Landman, I. [Karlsruhe Institute of Technology (KIT), IHM, 76344 Karlsruhe (Germany); Herashchenko, S.S.; Staltsov, V.V. [Institute of Plasma Physics of the NSC KIPT, 61108 Kharkov (Ukraine)

    2015-08-15

    Castellated edges of macro-brush armour elements of ITER divertor can be a source of molten/solid dust particles which are injected into the plasma. The targets that combined in brush-like geometry have been irradiated under different inclination angles in QSPA Kh-50. The cubic brushes element has typical size of 1 cm. The titanium was used to investigate dynamics of mountains’ formation. The onset of dust particles ejection from the exposed castellated targets has been studied. Formation of resolidified bridges through the gaps of brush-like targets due to the melt motion is studied in dynamics. With following plasma impacts such resolidified bridges became additional source of dust.

  9. Growing Embossed Nanostructures of Polymer Brushes on Wet-Etched Silicon Templated via Block Copolymers

    Science.gov (United States)

    Lu, Xiaobin; Yan, Qin; Ma, Yinzhou; Guo, Xin; Xiao, Shou-Jun

    2016-02-01

    Block copolymer nanolithography has attracted enormous interest in chip technologies, such as integrated silicon chips and biochips, due to its large-scale and mass production of uniform patterns. We further modified this technology to grow embossed nanodots, nanorods, and nanofingerprints of polymer brushes on silicon from their corresponding wet-etched nanostructures covered with pendent SiHx (X = 1-3) species. Atomic force microscopy (AFM) was used to image the topomorphologies, and multiple transmission-reflection infrared spectroscopy (MTR-IR) was used to monitor the surface molecular films in each step for the sequential stepwise reactions. In addition, two layers of polymethacrylic acid (PMAA) brush nanodots were observed, which were attributed to the circumferential convergence growth and the diffusion-limited growth of the polymer brushes. The pH response of PMAA nanodots in the same region was investigated by AFM from pH 3.0 to 9.0.

  10. Lung malignancy: Diagnostic accuracies of bronchoalveolar lavage, bronchial brushing, and fine needle aspiration cytology

    Science.gov (United States)

    Sareen, Rateesh; Pandey, C L

    2016-01-01

    Background: Early diagnosis of lung cancer plays a pivotal role in reducing lung cancer death rate. Cytological techniques are safer, economical and provide quick results. Bronchoscopic washing, brushing and fine needle aspirations not only complement tissue biopsies in the diagnosis of lung cancer but also comparable. Objectives: (1) To find out diagnostic yields of bronchioalveolar lavage, bronchial brushings, FNAC in diagnosis of lung malignancy. (2) To compare relative accuracy of these three cytological techniques. (3) To correlate the cytologic diagnosis with clinical, bronchoscopic and CT findings. (4) Cytological and histopathological correlation of lung lesions. Methods: All the patients who came with clinical or radiological suspicion of lung malignancy in two and a half year period were included in study. Bronchoalveolar lavage was the most common type of cytological specimen (82.36%), followed by CT guided FNAC (9.45%) and bronchial brushings (8.19%). Sensitivity, specificity, positive and negative predictive value for all techniques and correlation with histopathology was done using standard formulas. Results: The most sensitive technique was CT FNAC – (87.25%) followed by brushings (77.78%) and BAL (72.69%). CT FNAC had highest diagnostic yield (90.38%), followed by brushings (86.67%) and BAL (83.67%). Specificity and positive predictive value were 100 % each of all techniques. Lowest false negatives were obtained in CT FNAC (12.5%) and highest in BAL (27.3%). Highest negative predictive value was of BAL 76.95 % followed by BB 75.59% and CT FNAC 70.59%. Conclusion: Before administering antitubercular treatment every effort should be made to rule out malignancy. CT FNAC had highest diagnostic yield among three cytological techniques. BAL is an important tool in screening central as well as in accessible lesions. It can be used at places where CT guided FNAC is not available or could not be done due to technical or financial limitations PMID:27890992

  11. Photodegradable neutral-cationic brush block copolymers for nonviral gene delivery.

    Science.gov (United States)

    Hu, Xianglong; Li, Yang; Liu, Tao; Zhang, Guoying; Liu, Shiyong

    2014-08-01

    We report on the fabrication of a photodegradable gene-delivery vector based on PEO-b-P(GMA-g-PDMAEMA) neutral-cationic brush block copolymers that possess cationic poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) brushes for DNA compaction, poly(ethylene oxide) (PEO) as a hydrophilic block, and poly(glycidyl methacrylate) (PGMA) as the backbone. The PEO-b-P(GMA-g-PDMAEMA) copolymers were synthesized through the combination of reversible addition-fragmentation transfer (RAFT) polymerization and postmodification. A photocleavable PEO-based macroRAFT agent was first synthesized; next, the PEO-b-PGMA block copolymer was prepared by RAFT polymerization of GMA; this was followed by a click reaction to introduce the RAFT initiators on the side chains of the PGMA block; then, RAFT polymerization of DMAEMA afforded the PEO-b-P(GMA-g-PDMAEMA) copolymer. The obtained neutral-cationic brush block copolymer could effectively complex plasmid DNA (pDNA) into nanoparticles at an N/P ratio (i.e., the number of nitrogen residues per DNA phosphate) of 4. Upon UV irradiation, pDNA could be released owing to cleavage of the pDNA-binding cationic PDMAEMA side chains as well as the nitrobenzyl ester linkages at the diblock junction point. In addition, in vitro gene transfection results demonstrated that the polyplexes could be effectively internalized by cells with good transfection efficiency, and the UV irradiation protocol could considerably enhance the efficiency of gene transfection. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Organizing cross-border fire brigade response in the Dutch-German border region

    NARCIS (Netherlands)

    Boersma, F.K.; Engelman, E.

    2012-01-01

    This article addresses the opportunities and problems with cross-border collaboration between the Dutch and German fire brigades. The following are the main problems: 1) no uniformity in concluding and using the cross-border agreements for emergency assistance, 2) the language problem, 3) the

  13. Pit membranes of Ephedra resemble gymnosperms more than angiosperms

    Science.gov (United States)

    Roland Dute; Lauren Bowen; Sarah Schier; Alexa Vevon; Troy Best; Maria Auad; Thomas Elder; Pauline Bouche; Steven Jansen

    2014-01-01

    Bordered pit pairs of Ephedra species were characterized using different types of microscopy. Pit membranes contained tori that did not stain for lignin. SEM and AFM views of the torus surface showed no plasmodesmatal openings, but branched, secondary plasmodesmata were occasionally noted using TEM in conjunction with ultrathin sections. The margo consisted of radial...

  14. Lateral phase separation of mixed polymer brushes on planar and spherical surfaces

    Science.gov (United States)

    van Lehn, Reid; Alexander-Katz, Alfredo

    2012-02-01

    A mixed polymer brush consists of two (or more) polymer species grafted to a surface at a high density, inducing the polymers to highly stretch to maximize favorable solvent interactions while minimizing polymer overlap. The enthalpic and entropic interactions between the different polymers give rise to lateral phase behavior on the surface. Understanding this phase separation behavior is interesting for applications in nanotemplating and controlled protein adsorption. In this work, we present a novel theoretical model to quickly predict lateral phase separated morphologies of mixed polymer brushes on planar, cylindrical and spherical surfaces. The model combines a Flory-Huggins model for enthalpic interactions between the polymer components with an Alexander-de Gennes model for the entropy of the brush layers. When there is a length difference between the polymer components, these two interactions along with the conformational entropy of the system lead to a range of morphologies including stripes, dimples, mixing, and complete phase separation. The computational efficiency of this model allows for phase diagrams to be generated with great accuracy. The results of our model thus allow for the fast prediction of lateral morphologies on different geometries.

  15. Polymer brushes infiltrated by nanoparticles and applications to the nuclear pore complex

    Science.gov (United States)

    Opferman, Michael G.

    Systems of grafted polymers in the presence of additives are useful in a variety of contexts including industrial applications, solar cells, organic electronics, drug delivery, and nucleocytoplasmic transport. In this thesis, we will consider the morphologies that polymer brushes attain when exposed to a solution of additives (which we generically term "nanoparticles"), particularly when those nanparticles interact attractively with the polymers. We find that nanoparticles of this type can have a dramatic effect on the height of the polymer chains above the grafting surface, and they can induce highly non-uniform morphologies, including ones in which a dense layer of nanoparticles and monomers forms near the grafting surface. We consider especially the relevance of the system to several experiments performed on biopolymers in the nuclear pore complex when they interact attractively with transport factors that regulate nucleocytoplasmic transport. We find that, although these experiments appear to give inconsistent results, the inconsistencies can be reconciled through two simple models: the Alexander-de Gennes polymer brush, and the Milner-Witten-Cates polymer brush. Our findings should contribute to the understanding of the nuclear pore complex in that experiments can be better understood in the context of their relevant control parameters.

  16. The Intersectionality of Border Pedagogy and Latino/a Youth: Enacting Border Pedagogy in Multiple Spaces

    Science.gov (United States)

    Ramirez, Pablo C.; Ross, Lydia; Jimenez-Silva, Margarita

    2016-01-01

    In this one-year qualitative study, the authors examined how border pedagogy is enacted by two Latino/a high school teachers in a border community in Southern California. Through classroom observations, the authors documented powerful student discussions that named complex borders (Giroux, 1992) that existed in their daily lives. We drew from…

  17. Polymer brush-functionalized chitosan hydrogels as antifouling implant coatings

    Czech Academy of Sciences Publication Activity Database

    Buzzacchera, I.; Vorobii, M.; Kostina, N. Yu.; de los Santos Pereira, Andres; Riedel, Tomáš; Bruns, M.; Ogieglo, W.; Möller, M.; Wilson, C. J.; Rodriguez-Emmenegger, C.

    2017-01-01

    Roč. 18, č. 6 (2017), s. 1983-1992 ISSN 1525-7797 R&D Projects: GA ČR(CZ) GBP205/12/G118 Institutional support: RVO:61389013 Keywords : chitosan * hemocompatible * polymer brushes Subject RIV: CE - Biochemistry OBOR OECD: Biochemistry and molecular biology Impact factor: 5.246, year: 2016

  18. Mechanism of ochratoxin A transport in kidney

    International Nuclear Information System (INIS)

    Sokol, P.P.; Ripich, G.; Holohan, P.D.; Ross, C.R.

    1988-01-01

    The effect of the fungal metabolite (mycotoxin) Ochratoxin A (OTA) on the transport of p-amino[ 3 H]hippurate (PAH), a prototypic organic anion, was examined in renal brush border (BBMV) and basolateral membrane vesicles (BLMV). OTA was as effective an inhibitor of PAH uptake in both membranes as probenecid. The dose response curves for OTA in BBMV and BLMV gave IC50 values of 20 +/- 6 and 32 +/- 7 microM, respectively. The effect was specific since the transport of the organic cation N1-methylnicotinamide was not affected. The phenomenon of counterflow was studied to establish that OTA is translocated. OTA produced trans stimulation of PAH transport in both BBMV and BLMV, demonstrating that OTA is transported across both these membranes. The data suggest that OTA interacts with the PAH transport system in both BBMV and BLMV. We conclude that OTA transport in the kidney is mediated via the renal organic anion transport system

  19. Brush Polymer of Donor-Accepter Dyads via Adduct Formation between Lewis Base Polymer Donor and All Carbon Lewis Acid Acceptor

    Directory of Open Access Journals (Sweden)

    Yang Wang

    2017-09-01

    Full Text Available A synthetic method that taps into the facile Lewis base (LB→Lewis acid (LA adduct forming reaction between the semiconducting polymeric LB and all carbon LA C60 for the construction of covalently linked donor-acceptor dyads and brush polymer of dyads is reported. The polymeric LB is built on poly(3-hexylthiophene (P3HT macromers containing either an alkyl or vinyl imidazolium end group that can be readily converted into the N-heterocyclic carbene (NHC LB site, while the brush polymer architecture is conveniently constructed via radical polymerization of the macromer P3HT with the vinyl imidazolium chain end. Simply mixing of such donor polymeric LB with C60 rapidly creates linked P3HT-C60 dyads and brush polymer of dyads in which C60 is covalently linked to the NHC junction connecting the vinyl polymer main chain and the brush P3HT side chains. Thermal behaviors, electronic absorption and emission properties of the resulting P3HT-C60 dyads and brush polymer of dyads have been investigated. The results show that a change of the topology of the P3HT-C60 dyad from linear to brush architecture enhances the crystallinity and Tm of the P3HT domain and, along with other findings, they indicate that the brush polymer architecture of donor-acceptor domains provides a promising approach to improve performances of polymer-based solar cells.

  20. Numerical investigation of the contraction of neutral-charged diblock copolymer brushes in electric fields

    International Nuclear Information System (INIS)

    Chen, Yuwei; Li, Haiming; Zhu, Yuejin; Tong, Chaohui

    2016-01-01

    Using self-consistent field theory (SCFT), the contraction of neutral-charged A-B diblock copolymer brushes in electric fields generated by opposite surface charges on two parallel electrodes has been numerically investigated. The diblock copolymer chains were grafted with the free end of the neutral block to one electrode and immersed in a salt-free solution sandwiched between the two electrodes. The numerical results reveal that the charged monomers, A-B joint segment and the tail exhibit bimodal distributions under external electric fields, which are absent for homopolymer polyelectrolyte brushes. The dependences of the relative populations and peak positions of the two modes on various parameters such as block ratio, grafting density, chain length and strength of the applied electric field were systematically examined and the underlining mechanisms were elucidated. It was found in this study that, if the total amount of surface charges on the grafting electrode is no more than that of the counter-ions in the system, overall charge neutrality is generally maintained inside the brushes when including the contribution of surface charges on the grafting electrode. In such a case, the counter-ions expelled from the brushes are highly enriched in the immediate vicinity of the second electrode and an approximate charge balance between these expelled counter-ions and the opposite surface charges on the second electrode is achieved. (paper)

  1. Temporary reintroduction of border controls at French borders inside the Schengen Area

    CERN Multimedia

    2015-01-01

    The French authorities have informed CERN that, in view of the upcoming COP21 Paris Climate Conference, France will exceptionally reintroduce controls at its borders with Schengen states for one month from 13 November to 13 December 2015. All border posts and crossing points between France and Switzerland will be affected by this measure.   Members of the personnel are therefore reminded that, when crossing borders within the Schengen Area*, they must carry: either, in the case of citizens of European Economic Area (EEA) countries and Switzerland, an official identity document (identity card or passport); or, in the case of non-EEA and non-Swiss citizens, an identity document together with a Schengen visa if they are subject to this obligation, or an identity document together with a residence permit issued by a Schengen state** if they have one.   The French authorities will make every effort to limit the impact of this measure on cross-border traffic, and wish to thank the members of th...

  2. Effect of the US-Mexico border region in cardiovascular mortality: ecological time trend analysis of Mexican border and non-border municipalities from 1998 to 2012.

    Science.gov (United States)

    Anaya, Gabriel; Al-Delaimy, Wael K

    2017-05-06

    An array of risk factors has been associated with cardiovascular diseases, and developing nations are becoming disproportionately affected by such diseases. Cardiovascular diseases have been reported to be highly prevalent in the Mexican population, but local mortality data is poor. The Mexican side of the US-Mexico border has a culture that is closely related to a developed nation and therefore may share the same risk factors of cardiovascular diseases. We wanted to explore if there was higher cardiovascular mortality in the border region of Mexico compared to the rest of the nation. We conducted a population based cross-sectional time series analysis to estimate the effects of education, insurance and municipal size in Mexican border (n = 38) and non-border municipalities (n = 2360) and its association with cardiovascular age-adjusted mortality rates between the years 1998-2012. We used a mixed effect linear model with random effect estimation and repeated measurements to compare the main outcome variable (mortality rate), the covariates (education, insurance and population size) and the geographic delimiter (border/non-border). Mortality due to cardiovascular disease was consistently higher in the municipalities along the US-Mexico border, showing a difference of 78 · 5 (95% CI 58 · 7-98 · 3, p Insurance coverage showed an increase in cardiovascular mortality of 3 · 6 (95% CI 3 · 1-4 · 0, p Mexico border region is disproportionately affected by cardiovascular disease mortality as compared to the non-border region of Mexico. This was not explained by education, population density, or insurance coverage. Proximity to the US culture and related diet and habits can be explanations of the increasing mortality trend.

  3. Investigating the dominant corrections to the strong-stretching theory for dry polymeric brushes.

    Science.gov (United States)

    Matsen, M W

    2004-07-22

    The accuracy of strong-stretching theory (SST) is examined against a detailed comparison to self-consistent field theory (SCFT) on dry polymeric brushes with thicknesses of up to approximately 17 times the natural chain extension. The comparison provides the strongest evidence to date that SST represents the exact thick-brush limit of SCFT. More importantly, it allows us to assess the effectiveness of proposed finite-stretching corrections to SST. Including the entropy of the free ends is shown to rectify the most severe inaccuracies in SST. The proximal layer proposed by Likhtman and Semenov provides another significant improvement, and we identify one further effect of similar importance for which there is not yet an accurate treatment. Furthermore, our study provides a valuable means of rejecting mistaken refinements to SST, and indeed one such example is revealed. A proper treatment of finite-stretching corrections is vital to a wide range of phenomena that depend on a small excess free energy, such as autophobic dewetting and the interaction between opposing brushes.

  4. Symmetry or asymmetry? Cross-border openness of service providers in Polish-Czech and Polish-German border towns

    Directory of Open Access Journals (Sweden)

    Dołzbłasz Sylwia

    2015-03-01

    Full Text Available The symmetry and/or asymmetry in terms of cross-border openness of service providers is examined in this article, for the cases of two border twin towns: Cieszyn/Český Těšín at the Polish-Czech border, and Gubin/Guben at the Polish-German border. To assess the level of openness of firms towards clients from the other side of the border, four trans-border categories were examined: neighbour’s language visible at store location; business offers in the language of the neighbour; the possibilities of payment in the neighbour’s currency; and the staff’s knowledge of the language. This enabled a comparison of both parts of the particular twin towns in relation to the character of cross-border openness, as well as an assessment of their symmetry/asymmetry. Comparisons of Gubin/Guben and Cieszyn/Český Těšín with respect to the analysed features were also carried out. The analysis shows significant variation in the level of cross-border openness towards clients from neighbouring countries. Whereas in the Polish-Czech town a relative symmetry was observed, in the Polish-German case, significant asymmetry was noted.

  5. Border Malaria Associated with Multidrug Resistance on Thailand-Myanmar and Thailand-Cambodia Borders: Transmission Dynamic, Vulnerability, and Surveillance

    Science.gov (United States)

    Bhumiratana, Adisak; Intarapuk, Apiradee; Sorosjinda-Nunthawarasilp, Prapa; Maneekan, Pannamas; Koyadun, Surachart

    2013-01-01

    This systematic review elaborates the concepts and impacts of border malaria, particularly on the emergence and spread of Plasmodium falciparum and Plasmodium vivax multidrug resistance (MDR) malaria on Thailand-Myanmar and Thailand-Cambodia borders. Border malaria encompasses any complex epidemiological settings of forest-related and forest fringe-related malaria, both regularly occurring in certain transmission areas and manifesting a trend of increased incidence in transmission prone areas along these borders, as the result of interconnections of human settlements and movement activities, cross-border population migrations, ecological changes, vector population dynamics, and multidrug resistance. For regional and global perspectives, this review analyzes and synthesizes the rationales pertaining to transmission dynamics and the vulnerabilities of border malaria that constrain surveillance and control of the world's most MDR falciparum and vivax malaria on these chaotic borders. PMID:23865048

  6. Sulfobetaine-based polymer brushes in marine environment: Is there an effect of the polymerizable group on the antifouling performance?

    NARCIS (Netherlands)

    Quintana, R.; Janczewski, D.; Vasantha, V.A.; Jana, S.; Lee, S.S.C.; Parra-Velandia, F.J.; Guo, S.; Parthiban, A.; Teo, S.L-M.; Vancso, Gyula J.

    2014-01-01

    Three different zwitterionic polymer brush coatings for marine biofouling control were prepared bysurface-initiated atom transfer radical polymerization (ATRP) of sulfobetaine-based monomers includingmethacrylamide (SBMAm), vinylbenzene (SBVB) and vinylimidazolium (SBVI). None of these brush

  7. Morphological and functional changes in the enterocyte induced by fructose

    DEFF Research Database (Denmark)

    Danielsen, E M; Hansen, Gert Helge; Wetterberg, L L

    1991-01-01

    In the presence of 10-50 mM-fructose, enterocytes of organ-cultured pig intestinal-mucosal explants fail to glycosylate correctly their newly synthesized microvillar enzymes, and instead degrade them [Danielsen (1989) J. Biol. Chem. 264, 13726-13729]. In the present work, this degradation was shown....... Thus the stack of Golgi cisternae was condensed and devoid of dilated rims, and the secretion of a non-glycosylated protein, apolipoprotein A-1, was almost completely blocked in the presence of fructose, showing that transport through the secretory pathway is disturbed even for proteins unaffected...... by the defective glycosylation. The microvilli of the brush-border membrane were markedly shortened (by about 40%) in the presence of fructose, and incorporation of newly made actin into the microvillar cytoskeleton was similarly decreased. By affecting membrane glycoprotein synthesis, the common dietary sugar...

  8. Electric double layer electrostatics of pH-responsive spherical polyelectrolyte brushes in the decoupled regime.

    Science.gov (United States)

    Li, Hao; Chen, Guang; Das, Siddhartha

    2016-11-01

    Understanding the behavior and properties of spherical polyelectrolyte brushes (SPEBs), which are polyelectrolyte brushes grafted to a spherical core, is fundamental to many applications in biomedical, chemical and petroleum engineering as well as in pharmaceutics. In this paper, we study the pH-responsive electrostatics of such SPEBs in the decoupled regime. In the first part of the paper, we derive the scaling conditions in terms of the grafting density of the PEs on the spherical core that ensure that the analysis can be performed in the decoupled regime. In such a regime the elastic and the excluded volume effects of polyelectrolyte brushes (PEBs) can be decoupled from the electrostatic effects associated with the PE charge and the induced EDL. As a consequence the PE brush height, assumed to be dictated by the balance of the elastic and excluded volume effects, can be independent of the electrostatic effects. In the second part, we quantify the pH-responsive electrostatics of the SPEBs - we pinpoint that the radial monomer distribution for a given brush molecule exhibit a non-unique cubic distribution that decays away from the spherical core. Such a monomer distribution ensures that the hydrogen ion concentration is appropriately accounted for in the description of the SPEB thermodynamics. We anticipate that the present analysis, which provides possibly one of the first models for probing the electrostatics of pH-responsive SPEBs in a thermodynamically-consistent framework, will be vital for understanding the behavior of a large number of entities ranging from PE-coated NPs and stealth liposomes to biomolecules like bacteria and viruses. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Brush seal leakage performance with gaseous working fluids at static and low rotor speed conditions

    Science.gov (United States)

    Carlile, Julie A.; Hendricks, Robert C.; Yoder, Dennis A.

    1992-01-01

    The leakage performance of a brush seal with gaseous working fluids at static and low rotor speed conditions was studied. The leakage results included for air, helium, and carbon dioxide at several bristle/rotor interferences. Also, the effects of packing a lubricant into the bristles and also of reversing the pressure drop across the seal were studied. Results were compared to that of an annular seal at similar operating conditions. In order to generalize the results, they were correlated using corresponding state theory. The brush seal tested had a bore diameter of 3.792 cm (1.4930 in.), a fence height of 0.0635 cm (0.025 in.), and 1800 bristles/cm circumference (4500 bristles/in. circumference). Various bristle/rotor radial interferences were achieved by using a tapered rotor. The brush seal reduced the leakage in comparison to the annular seal, up to 9.5 times. Reversing the pressure drop across the brush seal produced leakage rates approximately the same as that of the annular seal. Addition of a lubricant reduced the leakage by 2.5 times. The air and carbon dioxide data were successfully correlated using corresponding state theory. However, the helium data followed a different curve than the air and carbon dioxide data.

  10. Self-Assembly of Narrowly Dispersed Brush Diblock Copolymers with Domain Spacing more than 100 nm

    Science.gov (United States)

    Gu, Weiyin; Sveinbjornsson, Benjamin; Hong, Sung Woo; Grubbs, Robert; Russell, Thomas

    2012-02-01

    Self-assembled structures of high molecular weight (MW), narrow molecular weight distribution brush block copolymers containing polylactic acid (PLA) and polystyrene (PS) side chains with similar MWs were studied in both the melt and thin films. The polynorbornene-backbone-based brush diblock copolymers containing approximately equal volume fractions of each block self-assembled into highly ordered lamellae with domain spacing over 100 nm, as revealed by SAXS, GISAXS and AFM. The domain size increased approximately linearly with backbone length, which indicated an extended conformation of the backbone in the ordered state. The length of side chains also played a significant role in terms of controlling the domain size. As the degree of polymerization (DP) increased, the symmetric brush diblock copolymers with longer side chains tended to form larger lamellar microdomains in comparison to those that have the same DP but shorter side chains.

  11. Border Malaria Associated with Multidrug Resistance on Thailand-Myanmar and Thailand-Cambodia Borders: Transmission Dynamic, Vulnerability, and Surveillance

    Directory of Open Access Journals (Sweden)

    Adisak Bhumiratana

    2013-01-01

    Full Text Available This systematic review elaborates the concepts and impacts of border malaria, particularly on the emergence and spread of Plasmodium falciparum and Plasmodium vivax multidrug resistance (MDR malaria on Thailand-Myanmar and Thailand-Cambodia borders. Border malaria encompasses any complex epidemiological settings of forest-related and forest fringe-related malaria, both regularly occurring in certain transmission areas and manifesting a trend of increased incidence in transmission prone areas along these borders, as the result of interconnections of human settlements and movement activities, cross-border population migrations, ecological changes, vector population dynamics, and multidrug resistance. For regional and global perspectives, this review analyzes and synthesizes the rationales pertaining to transmission dynamics and the vulnerabilities of border malaria that constrain surveillance and control of the world’s most MDR falciparum and vivax malaria on these chaotic borders.

  12. Suppressing Pseudomonas aeruginosa adhesion via non-fouling polymer brushes

    Czech Academy of Sciences Publication Activity Database

    Rodriguez-Emmenegger, Cesar; Decker, A.; Surman, František; Preuss, C. M.; Sedláková, Zdeňka; Zydziak, N.; Barner-Kowollik, C.; Schwartz, T.; Barner, L.

    2014-01-01

    Roč. 4, č. 110 (2014), s. 64781-64790 ISSN 2046-2069 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0109; GA ČR GAP106/12/1451 Institutional support: RVO:61389013 Keywords : polymer brushes * tissue engineering * biology Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.840, year: 2014

  13. Brush Day & Night Phase III to Phase IV: ensuring that good oral health habits are sustainable.

    Science.gov (United States)

    Melo, Paulo; Fine, Charlotte; Malone, Sinead; Horn, Virginie

    2018-05-01

    Over the past 10 years, the FDI-Unilever Brush Day & Night partnership has significantly influenced the life of children worldwide through the implementation of school programmes for oral health education and prevention. This article reports the key facts and outcomes of Phase III of the partnership, and announces the launch of Phase IV. During Phase III, the expert advisors of the Brush Day & Night partnership conducted a longitudinal study to evaluate the impact of the '21 Day' programme in almost 8,000 children in 10 countries. Analysis revealed the effectiveness of the 21 Day programme in sustainably educating children to brush their teeth twice a day, with the greatest impact observed in children aged 7-9 years. With the launch of Phase IV, the Brush Day & Night partnership will continue to deliver its oral health school programme for 7-9 year-old children with a strengthened methodology, including randomized sampling and control groups. The scope of the evaluation will be broadened to include oral health-related quality of life indicators, and monitoring of the oral health knowledge of children's parents/carers. © 2018 FDI World Dental Federation.

  14. Versatile antifouling polyethersulfone filtration membranes modified via surface grafting of zwitterionic polymers from a reactive amphiphilic copolymer additive.

    Science.gov (United States)

    Zhao, Yi-Fan; Zhang, Pei-Bin; Sun, Jian; Liu, Cui-Jing; Yi, Zhuan; Zhu, Li-Ping; Xu, You-Yi

    2015-06-15

    Here we describe the development of versatile antifouling polyethersulfone (PES) filtration membranes modified via surface grafting of zwitterionic polymers from a reactive amphiphilic copolymer additive. Amphiphilic polyethersulfone-block-poly(2-hydroxyethyl methacrylate) (PES-b-PHEMA) was beforehand designed and used as the blending additive of PES membranes prepared by phase inversion technique. The surface enriched PHEMA blocks on membrane surface acted as an anchor to immobilize the initiating site. Poly(sulfobetaine methacrylate) (PSBMA) were subsequently grafted onto the PES blend membranes by surface-initiated atom transfer radical polymerization (SI-ATRP). The analysis of surface chemistry confirmed the successful grafting of zwitterionic PSBMA brushes on PES membrane surface. The resulted PES-g-PSBMA membranes were capable of separating proteins from protein solution and oil from oil/water emulsion efficiently. Furthermore, the modified membranes showed high hydrophilicity and strongly antifouling properties due to the incorporation of well-defined PSBMA layer. In addition, the PES-g-PSBMA membranes exhibited excellent blood compatibility and durability during the washing process. The developed antifouling PES membranes are versatile and can find their applications in protein filtration, blood purification and oil/water separation, etc. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Brush competition retards early stand development of planted ponderosa pine: update on a 24-year study

    Science.gov (United States)

    William W. Oliver

    1990-01-01

    Growth of ponderosa pine (Pinus ponderosa) was monitored for 24 years after planting at five different square spacings (6, 9. 12, 15, and 18 ft) in the presence or absence of competing brush on the westside Sierra Nevada. Spacing strongly influenced both mean dbh and basal area/ac. In plots maintained free of brush, diameters ranged from 5.1 in. at the 6-ft spacing to...

  16. The development of cross-border economic relations

    NARCIS (Netherlands)

    van Houtum, H.J.

    1998-01-01

    This dissertation investigates the influence of a state border on the development of cross-border economic relations in the European Union. The focus is on the frequency, number, and success of cross-border relations between firms in the border regions of the Netherlands and Belgium. The study fills

  17. Polymer brushes: a controllable system with adjustable glass transition temperature of fragile glass formers.

    Science.gov (United States)

    Xie, Shi-Jie; Qian, Hu-Jun; Lu, Zhong-Yuan

    2014-01-28

    We present results of molecular dynamics simulations for coarse-grained polymer brushes in a wide temperature range to investigate the factors that affect the glass transition in these systems. We focus on the influences of free surface, polymer-substrate interaction strength, grafting density, and chain length not only on the change of glass transition temperature Tg, but also the fragility D of the glass former. It is found that the confinement can enhance the dependence of the Tg on the cooling rate as compared to the bulk melt. Our layer-resolved analysis demonstrates that it is possible to control the glass transition temperature Tg of polymer brushes by tuning the polymer-substrate interaction strength, the grafting density, and the chain length. Moreover, we find quantitative differences in the influence range of the substrate and the free surface on the density and dynamics. This stresses the importance of long range cooperative motion in glass formers near the glass transition temperature. Furthermore, the string-like cooperative motion analysis demonstrates that there exists a close relation among glass transition temperature Tg, fragility D, and string length ⟨S⟩. The polymer brushes that possess larger string length ⟨S⟩ tend to have relatively higher Tg and smaller D. Our results suggest that confining a fragile glass former through forming polymer brushes changes not only the glass transition temperature Tg, but also the very nature of relaxation process.

  18. Cylindrical polymer brushes with dendritic side chains by iterative anionic reactions

    KAUST Repository

    Zhang, Hefeng; Qu, Chengke; He, Junpo

    2015-01-01

    We report in this paper an easy method for the synthesis of cylindrical polymer brushes with dendritic side chains through anionic reaction. The synthesis is accomplished by iteratively grafting a living block copolymer, polyisoprene-. b

  19. Salt-Induced Control of the Grafting Density in Poly(ethylene glycol) Brush Layers by a Grafting-to Approach

    DEFF Research Database (Denmark)

    Ortiz, Roberto; Olsen, Stefan; Thormann, Esben

    2018-01-01

    In this work, a method to obtain control of the grafting density during the formation of polymer brush layers by the grafting-to method of thiolated poly(ethylene glycol) onto gold is presented. The grafting density of the polymer chains was adjusted by adding Na2SO4 in concentrations between 0.......2 and 0.9 M to the aqueous polymer solution during the grafting process. The obtained grafting densities ranged from 0.26 to 1.60 chains nm-2, as determined by surface plasmon resonance. The kinetics of the grafting process were studied in situ by a quartz crystal microbalance with dissipation......, and a mushroom to brush conformational transition was observed when the polymer was grafted in the presence of Na2SO4. The transition from mushroom to brush was only observed for long periods of grafting, highlighting the importance of time to obtain high grafting densities. Finally, the prepared brush layer...

  20. Wetting phase diagrams of polyacid brush with a triple point.

    NARCIS (Netherlands)

    Mercurieva, A.A.; Iakovlev, P.A.; Zhulina, E.B.; Birshtein, T.M.; Leermakers, F.A.M.

    2006-01-01

    The (pre)wetting behavior of an annealed polyelectrolyte (PE) brush by an electrolyte solution that is strongly segregated from an apolar phase is analyzed. In this complex interface, there are interactions on various length scales. There are short-range interactions with the (uncharged) surface,

  1. Stable Protein-Repellent Zwitterionic Polymer Brushes Grafted from Silicon Nitride

    NARCIS (Netherlands)

    Nguyen, A.T.; Baggerman, J.; Paulusse, J.M.J.; Rijn, van C.J.M.; Zuilhof, H.

    2011-01-01

    Zwitterionic poly(sulfobetaine acrylamide) (SBMAA) brushes were grafted from silicon-rich silicon nitride (SixN4, x > 3) surfaces by atom transfer radical polymerization (ATRP) and studied in protein adsorption experiments. To this aim ATRP initiators were immobilized onto SixN4 through stable

  2. Cross-Border Exposures and Financial Contagion

    NARCIS (Netherlands)

    Degryse, H.A.; Elahi, M.A.; Penas, M.F.

    2009-01-01

    Integrated financial markets provide opportunities for expansion and improved risk sharing, but also pose threats of contagion risk through cross-border exposures. This paper examines cross-border contagion risk over the period 1999-2006. To that purpose we use aggregate cross-border exposures of

  3. Old Borders and New Bordering Capabilities: Cities as Frontier Zones

    Directory of Open Access Journals (Sweden)

    Saskia Sassen

    2015-12-01

    Full Text Available The global city is a new frontier zone. Deregulation, privatization, and new fiscal and monetary policies create the formal instruments to construct their equivalent of the old military “fort”. The city is also a strategic frontier zone for those who lack power, and allows the making of informal politics. At the same time the border is a mix of regimes, marked by protections and opportunities for corporations and high-level professionals, and implies confinement, capture and detention for migrants. The essay discusses the transformation of the city in a frontier zone and analyses the separation between the capabilities entailed by territoriality and the geographic territory tout court. The analysis focuses on the effects of neoliberal policies that, far from making this a borderless world, have actually multiplied the bordered spaces that allow firms and markets to move across conventional borders. Cities are therefore one of the key sites where new neoliberal norms are made and where new identities emerge.

  4. The Border Pedagogy Revisited

    Science.gov (United States)

    Kazanjian, Christopher John

    2011-01-01

    Border pedagogy is a multicultural educational approach utilized in multicultural settings to help students understand their histories and experiences and how it affects their identities and cultures. The approach seeks to produce intellectuals that transcend physical and metaphysical boundaries. The goal of border pedagogy is to remove cultural…

  5. Border of spacetime

    International Nuclear Information System (INIS)

    Harada, Tomohiro; Nakao, Ken-ichi

    2004-01-01

    It is still uncertain whether the cosmic censorship conjecture is true or not. To get a new insight into this issue, we propose the concept of the border of spacetime as a generalization of the spacetime singularity and discuss its visibility. The visible border, corresponding to the naked singularity, is not only relevant to mathematical completeness of general relativity but also a window into new physics in strongly curved spacetimes, which is in principle observable

  6. Extreme delta brush evolving into status epilepticus in a patient with anti-NMDA encephalitis

    Directory of Open Access Journals (Sweden)

    Aline Herlopian, MD

    2017-01-01

    Full Text Available Extreme delta brush (EDB is an EEG pattern unique to anti-NMDA encephalitis. It is correlated with seizures and status epilepticus in patients who have a prolonged course of illness. The etiology of the underlying association between EDB and seizures is not understood. We present a patient with anti-NMDA encephalitis who developed status epilepticus evolving from the high frequency activity of the extreme delta brush. This case demonstrates that EDB is not only a marker for a greater propensity for seizures but also directly implicated in seizure generation.

  7. [Relationship between first molar caries and eating and tooth brushing habits in elementary school children].

    Science.gov (United States)

    Fujiwara, Aiko; Takeda, Fumi

    2010-11-01

    The aim of the present study was to elucidate the relationship between eating and tooth brushing habits in the second grade of elementary school with first molar caries in the third to sixth grades. Subjects were 130 students at one elementary school in the Tokai region who were in the second grade in 2002, for which eating and tooth-brushing habits were ascertained by a self-administered questionnaire survey. A follow-up survey was conducted based on the 2002 to 2006 school dental examination record and analyses were performed on data from 104 students without first molar dental caries in the second grade. The incidences of first molar caries in the third grade were higher among students who ate cookies at least once daily or every 2 to 3 days, compared with those who ate cookies once a week or not at all in the second grade. Incidences were also higher among those whose daily frequency of tooth brushing was once or sometimes compared with twice or three times or more. Furthermore, the incidences of first molar caries in the fourth, fifth and sixth grades were higher among students who ate candy at least once daily or every 2 to 3 days, compared with those who ate candy once a week or not at all in the second grade. The intake frequency of cookies was related to the first molar caries in the third grade, and of candy for that in the fourth to sixth grades. Moreover, first molar caries in the third grade were also related to the daily frequency of second-grade tooth brushing. These findings suggest the importance of measures encouraging lower-grade elementary students to establish and maintain habits of tooth brushing and of limiting consumption of sweets, such as cookies and candy, in order to prevent caries in their permanent teeth during elementary school.

  8. Rangeland Brush Estimation Toolbox (RaBET): An Approach for Evaluating Brush Management Conservation Efforts in Western Grazing Lands

    Science.gov (United States)

    Holifield Collins, C.; Kautz, M. A.; Skirvin, S. M.; Metz, L. J.

    2016-12-01

    There are over 180 million hectares of rangelands and grazed forests in the central and western United States. Due to the loss of perennial grasses and subsequent increased runoff and erosion that can degrade the system, woody cover species cannot be allowed to proliferate unchecked. The USDA-Natural Resources Conservation Service (NRCS) has allocated extensive resources to employ brush management (removal) as a conservation practice to control woody species encroachment. The Rangeland-Conservation Effects Assessment Project (CEAP) has been tasked with determining how effective the practice has been, however their land managers lack a cost-effective means to conduct these assessments at the necessary scale. An ArcGIS toolbox for generating large-scale, Landsat-based, spatial maps of woody cover on grazing lands in the western United States was developed through a collaboration with NRCS Rangeland-CEAP. The toolbox contains two main components of operation, image generation and temporal analysis, and utilizes simple interfaces requiring minimum user inputs. The image generation tool utilizes geographically specific algorithms developed from combining moderate-resolution (30-m) Landsat imagery and high-resolution (1-m) National Agricultural Imagery Program (NAIP) aerial photography to produce the woody cover scenes at the Major Land Resource (MLRA) scale. The temporal analysis tool can be used on these scenes to assess treatment effectiveness and monitor woody cover reemergence. RaBET provides rangeland managers an operational, inexpensive decision support tool to aid in the application of brush removal treatments and assessing their effectiveness.

  9. Recent trends in cross-border banking

    NARCIS (Netherlands)

    De Haas, Ralph; van Horen, Neeltje; Beck, Thorsten; Casu, Barbara

    2017-01-01

    This chapter identifies a number of recent trends in European cross-border banking. The authors first distinguish between two main modes of international banking: cross-border versus multinational banking. Cross-border banking occurs when a bank in country A lends directly to a borrower in country

  10. Nonadhesive, silica nanoparticles-based brush-coated contact lens cases--compromising between ease of cleaning and microbial transmission to contact lenses.

    Science.gov (United States)

    Qu, Wenwen; Hooymans, Johanna M M; Qiu, Jun; de-Bont, Nik; Gelling, Onko-Jan; van der Mei, Henny C; Busscher, Henk J

    2013-05-01

    Surface properties of lens cases are determinant for their cleanability and for microbial transmission from lens cases to contact lenses (CLs). PEG-polymer-brush-coatings are known to decrease microbial adhesion more than other surface-coatings. Here, we applied a robust, silica nanoparticles-based brush-coating to polypropylene cases to evaluate their ease of cleaning and probability of bacterial transmission to CLs. Adhesion forces of nine bacterial strains (Pseudomonas, Staphylococci, and Serratia) to rigid CLs, polypropylene, and silica nanoparticles-based brush-coated polypropylene were measured using atomic-force-microscopy and subjected to Weibull analyses to yield bacterial transmission probabilities. Biofilms of each strain were grown in coated and uncoated cases and rinsed with a NaCl or antimicrobial lens care solution. Residual, viable organisms were quantified. Bacterial adhesion forces of all strains were significantly, up to tenfold smaller on brush-coated than on uncoated polypropylene. This yielded, higher transmission probabilities to a CL, but mild-rinsing yielded 10-100 fold higher removal of bacteria from brush-coated than from polypropylene cases. Moreover, due to weak adhesion forces, bacteria on brush-coated cases were two-to-three fold more susceptible to an antimicrobial lens care solution than on polypropylene cases. Therewith, the design of lens case surfaces is a compromise between ease of cleaning and transmission probability to CLs. Copyright © 2013 Wiley Periodicals, Inc.

  11. Briefing : the Eritrean-Ethiopian border dispute

    NARCIS (Netherlands)

    Abbink, G.J.

    1998-01-01

    On 6 May 1998, a violent conflict erupted in the Ethiopian-Eritrean border area. This article contends that this border crisis is neither unexpected nor the result of a real border dispute. Rather, it is due to three factors: the particular history and relationship of the two insurgent movements

  12. Stable Protein-Repellent Zwitterionic Polymer Brushes Grafted from Silicon Nitride

    NARCIS (Netherlands)

    Nguyen, Ai T.; Baggerman, Jacob; Paulusse, Jos Marie Johannes; van Rijn, Cees J.M.; Zuilhof, Han

    2011-01-01

    Zwitterionic poly(sulfobetaine acrylamide) (SBMAA) brushes were grafted from silicon-rich silicon nitride (SixN4, x > 3) surfaces by atom transfer radical polymerization (ATRP) and studied in protein adsorption experiments. To this aim ATRP initiators were immobilized onto SixN4 through stable Si−C

  13. An Eight-Week Clinical Evaluation of an Oscillating-Rotating Power Toothbrush with a Brush Head Utilizing Angled Bristles Compared with a Sonic Toothbrush in the Reduction of Gingivitis and Plaque.

    Science.gov (United States)

    Ccahuana-Vasquez, Renzo A; Conde, Erinn; Grender, Julie M; Cunningham, Pamela; Qaqish, Jimmy; Goyal, C Ram

    2015-01-01

    To evaluate and compare the efficacy of an oscillating-rotating (O-R) power toothbrush with a brush head utilizing angled bristles to a marketed sonic toothbrush in the reduction of plaque and gingivitis over an eight-week period. This study used a randomized, examiner-blind, single-center, two-treatment, parallel group, eight-week design. Subjects with mild-to-moderate plaque and gingivitis were evaluated for baseline whole mouth, gingival margin, and approximal plaque, gingivitis, and gingival bleeding. Clinical assessments were performed using the Modified Gingival Index, Gingival Bleeding Index, and the Rustogi Modified Navy Plaque Index. Subjects received either the O-R brush (Oral-B Professional Care 1000 [D16u] with Oral-B CrossAction brush head [EB50]) or the sonic brush (Sonicare DiamondClean with the standard DiamondClean brush head). Subjects brushed twice daily for two minutes per brushing with the assigned brush and a standard fluoride dentifrice for eight weeks before returning for plaque and gingivitis evaluations using the same methods. Prior to baseline and Week 8 measurements, participants abstained from oral hygiene for 12 hours. One hundred and forty-eight subjects completed the study; 75 in the O-R group and 73 in the sonic group. Both brushes demonstrated statistically significant reductions in plaque and gingivitis over the eight-week study period (p gingivitis than the sonic brush. Whole mouth, gingival margin, and approximal plaque reductions were 27.7%, 46.8%, and 29.3% greater, respectively, compared with the sonic brush, while the reductions in gingivitis, gingival bleeding, and number of bleeding sites were 34.6%, 36.4%, and 36.1% greater, respectively, for the O-R brush than for the sonic brush (p gingivitis reductions for the O-R power brush incorporating the angled-bristled brush head were significantly greater than for the sonic power brush.

  14. 13C-labeled 18 : 2n-6 recovered in brush border membrane phospholipids short time after administration

    DEFF Research Database (Denmark)

    Vistisen, Bodil; Høy, Carl-Erik

    2004-01-01

    fatty acids in the two phospholipid pools. Minor effects on BBM-PC and BBM-PE fatty acid profiles (mole-%) were observed. The present study demonstrated for the first time incorporation of C-13-labeled 18:2n-6 into BBM-PC 2 hours and 6 hours after intragastric administration of L*L*L* or ML......*M. This emphasizes the influence of the dietary fatty acid on BBM fatty acid composition and the rapid incorporation of dietary long-chain fatty acids into intestinal enterocyte phospholipids. Medium-chain fatty acids in a single meal exert only a minor influence on the BBM phospholipid fatty acid profile....

  15. A Voice of the US Southwestern Border: The 2012 “We the Border: Envisioning a Narrative for Our Future” Conference

    Directory of Open Access Journals (Sweden)

    Josiah McC. Heyman

    2013-08-01

    Full Text Available In July 2012, a diverse group of US residents living near the US-Mexico border met in El Paso, Texas for a conference entitled, We the Border: Envisioning a Narrative for Our Future.  This paper describes a vision for the US-Mexico border by diverse border residents that is at odds with the widespread view of the border as a threat to the United States. These border residents viewed their region as a set of human communities with rights, capacities, and valuable insights and knowledge. They embraced an alternative vision of border enforcement that would focus on “quality” (dangerous entrants and contraband over “quantity” (mass migration enforcement.  They called for investments in the functionality and security of ports of entry, rather than in between ports of entry.  They noted the low crime rate in US border cities, and examined how policies of not mixing local law enforcement with federal immigration enforcement contributed to this achievement. They saw the border region as the key transportation and brokerage zone of the emerging, integrated North American economy. In their view, the bilingual, bicultural, and binational skills that characterize border residents form part of a wider border culture that embraces diversity and engenders creativity. Under this vision the border region is not an empty enforcement zone, but is part of the national community and its residents should enjoy the same constitutional and human rights as other US residents. The conference participants emphasized the necessity and value of accountability and oversight of central government enforcement operations, and the need for border communities to participate in federal decision-making that affects their lives. 

  16. The effects of brushing on human enamel surface roughness after NaF gel and theobromine gel exposure

    Science.gov (United States)

    Mahardhika, A.; Noerdin, A.; Eriwati, Y. K.

    2017-08-01

    This study aimed to determine the effects of brushing on human enamel surface roughness after different exposure times of 200 mg/L theobromine gel (8, 16, and 32 minutes) and 2% NaF gel (16 minutes). Twenty-four human upper premolars were used and divided into four groups. Group 1 was exposed to 2% NaF gel for 16 minutes. In contrast, groups 2, 3, and 4 were exposed to 200 mg/L theobromine gel for 8 minutes, 16 minutes, and 32 minutes, and each group was then brushed for 9 minutes and 20 seconds. After the treatment, samples were tested using a surface roughness tester (Mitutoyo SJ 301, Japan). The Wilcoxon test showed significant changes (p enamel surface and then increase roughness after brushing.

  17. Biophysical characterization and functional studies on calbindin-D28K: A vitamin D-induced calcium-binding protein

    International Nuclear Information System (INIS)

    Leathers, V.L.

    1989-01-01

    Vitamin D dependent calcium binding protein, or calbindin-D, is the principal protein induced in the intestine in response to the steroid hormone 1,25(OH) 2 -vitamin D 3 . A definitive role for calbindin-D in vitamin D 3 mediated biological responses remains unclear. Biophysical and functional studies on chick intestinal calbindin-D 28K (CaBP) were initiated so that some insight might be gained into its relevance to the process of intestinal calcium transport. Calbindin-D belongs to a class of high affinity calcium binding proteins which includes calmodulin, parvalbumin and troponin C. The Ca 2+ binding stoichiometry and binding constants for calbindin-D 28K were quantitated by Quin 2 titration analysis. The protein was found to bind 5-6 Ca 2+ ions with a K D on the order of 10 -8 , in agreement with the 6 domains identified from the amino acid sequence. A slow Ca 2+ exchange rate (80 s -1 ) as assessed by 43 Ca NMR and extensive calcium dependent conformational changes in 1 H NMR spectra were also observed. Functional studies on chick intestinal CaBP were carried out by two different methods. Interactions between CaBP and intestinal cellular components were assessed via photoaffinity labeling techniques. Specific calcium dependent complexes for CaBP were identified with bovine intestinal alkaline phosphatase and brush border membrane proteins of 60 and 150 kD. CaBP was also found to co-migrate with the alkaline phosphatase activity of chick intestinal brush border membranes as evaluated by gel filtration chromatography. The second procedure for evaluating CaBP functionality has involved the quantitation of CaBP association with vesicular transport components as assessed by ELISA. CaBP, immunoreactivity was observed in purified lysosomes, microsomes and microtubules

  18. Frequency and levels of autoantibodies in healthy adult Omanis

    International Nuclear Information System (INIS)

    Al-Jabri, Ali A.; A-Belushi Mohammad; Nanze, Herburt

    2003-01-01

    A previous pilot study showed high frequency of anti-smooth muscle autoantibody in Omani blood donors and pregnant women. We conducted this larger-scale study to investigate the frequency and significance of several autoantibodies in healthy individuals from different regions of Oman. Sera obtained from 1537 healthy Omanis (1153 males and 384 females ), ranging in age from 18 to 57 years, tested for the presence of ten different autoantibodies using indirect immunofluoresence, haemagglutination and latex agglutination techniques. Low levels of autoantibodies were detected in 33.5%, whereas a few individuals (1.8%) showed high autoantibody titres. Anti-smooth muscle autoantibodies (ASMA) were the most prevalent (11%). Anti-nuclear autoantibodies (ANA) were the second most prevalent (7.6%). Anti-thyroid microsomal autoantibodies (ATMA) and anti-thyroglobulin autoantibodies (ATA) were present in 6.5% and 4.4% of individuals,respectively. The other autoantibodies were detected much less frequently: anti-parietal cells autoandibodies (APCA) were found in 1.6%,anti-brush border antibodies (ABBA) in 1.3% anti-reticulin autoantibodies (ARA) in 1%, anti-mitochondrial antibodies in 0.8%, antiglomerular basement membrane antibodies (AGBMA) in 0.7% and rheumatoid factor(RF) in 0.4%.Low levels of autoantibodies were detected in 33.5%, whereas a few individuals (1.8%) showed high autoantibody titres. Anti-smooth muscle autoantibodies (ASMA) were the most prevalent (11%). Anti-nuclear autoantibodies (ANA) were the second most prevalent (7.6%). Anti-thyroid microsomal autoantibodies (ATMA) and anti-thyroglobulin autoantibodies (ATA) were present in 6.5% and 4.4% of individuals,respectively. The other autoantibodies were detected much less frequently: anti-parietal cells autoandibodies (APCA) were found in 1.6%,anti-brush border antibodies (ABBA) in 1.3% anti-reticulin autoantibodies (ARA) in 1%, anti-mitochondrial antibodies in 0.8%, antiglomerular basement membrane antibodies

  19. Role of lycopene against hepatorenal oxidative stress induced by sodium fluoride and gamma rays

    International Nuclear Information System (INIS)

    Mansour, H.H.; Abd El Azeem, M.G.; Ismael, N.E.R.

    2011-01-01

    Fluorosis is a serious public health problem in many parts of the world. The present study have been designed to evaluate the potential efficacy of lycopene in protecting the hepatic as well as renal tissues from the sodium fluoride (NaF) and gamma radiation (IRR) induced oxidative stress in male mice. Biochemical and histopathological examinations were utilized for evaluation of the oxidative stress, hepatotoxicity and nephrotoxicity. Results showed that NaF and IRR (2 Gy) caused elevation in liver and kidney MDA and NO (x) levels and reduction in SOD activity and GSH content. The activities of AST, ALT, LDH, ALP, urea nitrogen, creatinine and lipid profiles were increased, HDL-c was decreased. Ultrastructural examination of liver and kidney tissues confirmed the biochemical data. Irradiation exhibited hepatocytes with varying lesions that included lysis of cytoplasm with fragmented endoplasmic reticulum, dilated blood sinusoids with thickness membrane. Serious damage of the epithelial cells lining the proximal tubules of irradiated mice was manifested by development of dilated rough endoplasmic reticulum, swelling mitochondria and pyknotic nuclei also, degeneration in brush border. NaF induced degeneration in nucleus, mitochondria, erosion in brush border in kidney, fragmentation in endoplasmic reticulum, thickness of blood sinusoids membrane in liver. Serious damage of the hepatocytes and proximal tubules of the mice treated with NaF and exposed to irradiation. Administration of lycopene (5 mg/kg, oral gavage), prior to NaF and/or IRR, ameliorated the hepatotoxicity and nephrotoxicity induced by NaF and/or IRR. The present results revealed that lycopene has a protective effect against NaF and/or IRR-induced hepatotoxicity and nephrotoxicity by antagonizing the free radicals generation and enhancement of the antioxidant defense mechanisms.

  20. [An historical, sociocultural view and in the fiction literature of Bacillus anthracis cases by shaving brushes].

    Science.gov (United States)

    Vázquez-Espinosa, E; Laganà, C; Vazquez, F

    2018-06-01

    In the period from 1915 to 1924 anthrax outbreaks were described by Bacillus anthracis due to the contamination of razor brushes that reached Europe and the United States from areas such as Japan, China or Russia. The brushes were made with badger hair, and then, to reduce the cost with horse hair and other animals. World War I supoosed that the traffics of these brushes, that passed through Europe, changed and the processes of sterilization of the same were deficient giving rise to these outbreaks, that in a percentage of 20% produced the death of the users. The impact of the fashion of wearing a beard, the presence of these cases in the press, in the society of that period, and literature are studied through the work of Agatha Christie who wrote, in 1936, the Hercules Poirot´s novel Cards on the table, and where she describes the murder of one of the characters with the shaving brush contaminated with Bacillus anthracis spores. ©The Author 2018. Published by Sociedad Española de Quimioterapia. This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)(https://creativecommons.org/licenses/by-nc/4.0/).

  1. Badger hair in shaving brushes comes from protected Eurasian badgers

    NARCIS (Netherlands)

    Domingo-Roura, X.; Marmi, J.; Ferrando, A.; López-Giráldez, F.; Macdonald, D.W.; Jansman, H.A.H.

    2006-01-01

    The Eurasian badger (Meles meles) is included in Appendix III of the Bern Convention and protected by national laws in many European countries. Badger hair is used to manufacture luxury shaving brushes, although it is frequently argued that the hog badger (Arctonyx collaris), which in Europe is an

  2. Time and temperature dependent analytical stability of dry-collected Evalyn HPV self-sampling brush for cervical cancer screening

    DEFF Research Database (Denmark)

    Ejegod, Ditte Møller; Pedersen, Helle; Alzua, Garazi Peña

    2018-01-01

    As a new initiative, HPV self-sampling to non-attenders using the dry Evalyn self-sampling brush is offered in the Capital Region of Denmark. The use of a dry brush is largely uncharted territory in terms of analytical stability. In this study we aim to provide evidence on the analytical quality...

  3. Carbon nanotube surface modification with polyelectrolyte brushes endowed with quantum dots and metal oxide nanoparticles through in situ synthesis

    International Nuclear Information System (INIS)

    Llarena, Irantzu; Romero, Gabriela; Moya, Sergio E; Ziolo, Ronald F

    2010-01-01

    Carbon nanotubes (CNTs) have been successfully coated with a covalently bonded polymer brush of negatively charged poly(3-sulfopropylamino methacrylate) (PSPM) by in situ polymerization employing atomic transfer radical polymerization (ATRP) from initiating silanes attached to the CNTs before the polymerization. The CNT-bonded brush forms a polymer layer or shell-like structure around the CNTs and provides colloidal stabilization for the CNTs in aqueous media. In situ syntheses of nanocrystalline CdS and magnetic iron oxide in the polymer brushes lead to the formation of hybrid nanocomposites consisting of nanoparticle-containing PSPM-coated CNTs that remain readily dispersible and stable in aqueous media. The hybrid nanostructures are synthesized by ion exchange with the cations of the sulfonate groups of the PSPM followed by precipitation and were followed by stepwise zeta potential measurements and TEM. Such structures could have applications in the design of more complex structures and devices. The general synthetic scheme can be extended to include other nanoparticles as brush cargo to broaden the utility or functionality of the CNTs. TEM data shows nanocrystalline CdS in the range of 5-8 nm embedded in the PSPM brush and nanocrystalline iron oxide with a size between 2 and 4 nm, with the former consistent with UV-vis spectroscopy and fluorescence measurements.

  4. Crossing borders via mental bridges

    DEFF Research Database (Denmark)

    Keil, Dirk

    The project studies cross-border regional integration in Europe drawing on the example of the emerging Danish-German Femern Belt Region. It focuses on cross-border networking within public administration as part of regional integra- tion. My central question is how national-cultural differences...... influence coopera- tion, coordination and collaboration in administrative cross-border networks. In this connection the project asks after the perception of regional integration seen from the different national backgrounds. The research concentrates on the group of decision makers within the field of public...... administration, and in specific on the attempt to initiate and promote cross-border regional integration via the building of mental bridges between Danish and German parts of the Femern Belt Region. Here one of the first projects aiming primarily at building mental bridges in the Femern Belt Region...

  5. Regional Joint Border Commands: A Pathway to Improving Collaboration and Effectiveness for Border Control

    Science.gov (United States)

    2009-12-01

    Police xii SBI Secure Border Initiative SES Senior Executive Service SSP Secretaria de Seguridad Publica TSA Transportation Security...also been involvement from the Mexican law enforcement agency, Secretaria de Seguridad Publica (SSP) on the southwest border (CBP, 2009; ICE, 2009, p. 5

  6. Value of brush cytology for dominant strictures in primary sclerosing cholangitis

    NARCIS (Netherlands)

    Ponsioen, C. Y.; Vrouenraets, S. M.; van Milligen de Wit, A. W.; Sturm, P.; Tascilar, M.; Offerhaus, G. J.; Prins, M.; Huibregtse, K.; Tytgat, G. N.

    1999-01-01

    Around 10% of patients with primary sclerosing cholangitis (PSC) develop cholangiocarcinoma, which is cholangiographically often indistinguishable from a benign dominant stricture. The aim of the present study was to assess the value of brush cytology in discriminating between benign and malignant

  7. Streptococcus mutans adhesion to titanium after brushing with fluoride and fluoride-free toothpaste simulating 10 years of use.

    Science.gov (United States)

    Fais, Laiza M G; Carmello, Juliana C; Spolidorio, Denise M P; Adabo, Gelson L

    2013-01-01

    To assess the influence of fluoride on the adhesion of Streptococcus mutans to titanium using an experimental paradigm simulating 10 years of brushing. Commercially pure titanium (cpTi) and titanium alloy (Ti-6Al-4V) disks (6 mm in diameter and 4 mm thick) were mirror-polished and randomly assigned to one of the following six groups (n = 6): immersion (I) or brushing (B) in deionized water (groups IW [control] and BW), fluoride-free toothpaste (groups IT and BT), or fluoridated toothpaste (groups IFT and BFT). Specimens subjected to immersion were statically submerged into the solutions without brushing. For the brushed specimens, a linear brushing machine with a soft-bristled toothbrush was used. The experiments lasted a total of 244 hours. Before and after treatment, the specimens were analyzed under an atomic force microscope to determine the mean roughness (Ra) and the mean of the maximum peak-to-valley heights of the profile (Rtm). The disks were contaminated with standard strains of S mutans in well plates with brain-heart infusion broth. Adhesion was analyzed based on the numbers of colony-forming units (CFU/mL) of adhered viable cells using scanning electronic microscopy. Differences in CFU/mL between the groups were analyzed by one-way analysis of variance. Immersion did not affect either surface. As suggested by Ra and Rtm, BW, BT, and BFT induced changes on the surface of cpTi, whereas only BT and BTF induced changes on the surface of Ti-6Al-4V. No significant differences were observed regarding CFU/mL among the cpTi or Ti-6Al-4V groups. S mutans adhesion was similar for all surfaces. The changes in titanium induced by 10 years of simulated brushing with fluoride toothpaste did not increase the adhesion of S mutans.

  8. Canada and Mexico Border Crossings

    Data.gov (United States)

    Department of Homeland Security — Border Crossing Ports are points of entry for land modes along the U.S. - Canadian and U.S.- Mexcian borders. The ports of entry are located in 15 states along the...

  9. Internal Border Controls in the European Union

    DEFF Research Database (Denmark)

    Jørgensen, Carsten Willemoes; Sørensen, Karsten Engsig

    2012-01-01

    Recent events, involving inter alia France and Denmark, have stimulated renewed interest in the introduction of different forms of border controls at the internal borders within the European Union. These border control measures are aimed at checking either persons or goods or both. Against...... the background of these events, this article analyses the existing rules regulating controls of persons and goods, and explores how these rules may or may not stand in the way of introducing border controls at the European Union’s internal borders. These events have resulted in a call for reforms of the current...

  10. A novel miniaturized zinc oxide/hydroxylated multiwalled carbon nanotubes as a stir-brush microextractor device for carbamate pesticides analysis

    International Nuclear Information System (INIS)

    Makkliang, Fonthip; Kanatharana, Proespichaya; Thavarungkul, Panote; Thammakhet, Chongdee

    2016-01-01

    A novel miniaturized “stir-brush microextractor” was prepared using a zinc oxide/hydroxylated multiwalled carbon nanotubes (ZnO/MWCNTs–OH) coated stainless steel brush connected to a small dc motor. The synthesized zinc oxide on each strand of stainless steel had a flower-like nanostructure when observed by a scanning electron microscope (SEM). This structure produced a large surface area before it was coated with the hydroxylated multiwalled carbon nanotubes sorbent. Under optimal conditions, the developed device provided a good linearity for the extraction of carbofuran and carbaryl, in the range of 25–500 ng mL"−"1 and 50–500 ng mL"−"1, respectively, with low limits of detection of 17.5 ± 2.0 ng mL"−"1 and 13.0 ± 1.8 ng mL"−"1. It also provided a good stir-brush-to-stir-brush reproducibility (% relative standard deviation < 5.6%, n = 6). The device was applied for the extraction and preconcentration of carbamate pesticides in fruit and vegetable samples prior to analysis with a gas chromatograph coupled with a flame ionization detector (GC–FID). Carbofuran was found at 9.24 ± 0.93 ng g"−"1 and carbaryl was detected at 7.05 ± 0.61 ng g"−"1 with good recoveries in the range of 73.7 ± 10.0% to 108.4 ± 2.6% for carbofuran and 75.7 ± 10.0% to 111.7 ± 5.7% for carbaryl. - Highlights: • A brush as the sampling tool was first introduced. • A novel miniaturized and portable stir brush microextractor was developed for carbamate pesticides extraction. • Large surface area of ZnO flower-like nanostructure coated with MWCNTs–OH on each brush fiber was observed.

  11. A novel miniaturized zinc oxide/hydroxylated multiwalled carbon nanotubes as a stir-brush microextractor device for carbamate pesticides analysis

    Energy Technology Data Exchange (ETDEWEB)

    Makkliang, Fonthip; Kanatharana, Proespichaya [Trace Analysis and Biosensor Research Center, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Center of Excellence for Innovation in Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Department of Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Thavarungkul, Panote [Trace Analysis and Biosensor Research Center, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Center of Excellence for Innovation in Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Department of Physics, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Thammakhet, Chongdee, E-mail: chongdee.t@psu.ac.th [Trace Analysis and Biosensor Research Center, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Center of Excellence for Innovation in Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Department of Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand)

    2016-04-21

    A novel miniaturized “stir-brush microextractor” was prepared using a zinc oxide/hydroxylated multiwalled carbon nanotubes (ZnO/MWCNTs–OH) coated stainless steel brush connected to a small dc motor. The synthesized zinc oxide on each strand of stainless steel had a flower-like nanostructure when observed by a scanning electron microscope (SEM). This structure produced a large surface area before it was coated with the hydroxylated multiwalled carbon nanotubes sorbent. Under optimal conditions, the developed device provided a good linearity for the extraction of carbofuran and carbaryl, in the range of 25–500 ng mL{sup −1} and 50–500 ng mL{sup −1}, respectively, with low limits of detection of 17.5 ± 2.0 ng mL{sup −1} and 13.0 ± 1.8 ng mL{sup −1}. It also provided a good stir-brush-to-stir-brush reproducibility (% relative standard deviation < 5.6%, n = 6). The device was applied for the extraction and preconcentration of carbamate pesticides in fruit and vegetable samples prior to analysis with a gas chromatograph coupled with a flame ionization detector (GC–FID). Carbofuran was found at 9.24 ± 0.93 ng g{sup −1} and carbaryl was detected at 7.05 ± 0.61 ng g{sup −1} with good recoveries in the range of 73.7 ± 10.0% to 108.4 ± 2.6% for carbofuran and 75.7 ± 10.0% to 111.7 ± 5.7% for carbaryl. - Highlights: • A brush as the sampling tool was first introduced. • A novel miniaturized and portable stir brush microextractor was developed for carbamate pesticides extraction. • Large surface area of ZnO flower-like nanostructure coated with MWCNTs–OH on each brush fiber was observed.

  12. three intelligence methodologies for border defence and border

    African Journals Online (AJOL)

    Administrator

    Of these there are three intelligence methodologies applicable to this article – trends ..... globalisation associated with open and artificial borders and ever increasing costs of weapon ..... the technological development of mass tourist transport.

  13. Okadaic acid

    DEFF Research Database (Denmark)

    Danielsen, E Michael; Hansen, Gert H; Severinsen, Mai C K

    2014-01-01

    are the hallmark of phospholipidosis, a pathological condition characterized by lysosomal phospholipid accumulation. Phospholipidosis is observed in acquired lysosomal storage diseases and is induced by a large number of cationic amphiphilic drugs. Unlike the latter, however, OA does not act by accumulating...... in acidic organelles, implying a different toxic mechanism of action. We propose that rapid induction of LBs, an indicator of phospholipidosis, should be included in the future toxicity profile of OA....... hyper protein phosphorylation, but no detectable loss of cell polarity or cytoskeletal integrity of the enterocytes. Using a fluorescent membrane marker, FM dye, endocytosis from the brush border was affected by the toxin. Although constitutive uptake into subapical terminal web-localized early...

  14. The Nature and Functions of European Political Borders

    Directory of Open Access Journals (Sweden)

    Jernej Zupančič

    2008-07-01

    Full Text Available The political border limits a state’s territory and symbolizes the extent of a state’s power and ownership. Borders give integrity to the inner state territory which they enclose (the role of establishing national integrity and at the same time form an outer boundary segregating the state territory from the surrounding politicial entities (the segregation role. European borders are old and reflect the political history of an old continent. The last major border changes happened after World War II. Over the centuries borders were merely lines separating one territory from another. Such borders were understood as »frontiers«. Forming an effective barrier against enemies was the overriding function of borders. Many borders were fortified and further enhanced by means of various defensive systems. In the second half of the 20th century the character of political borders changed. They became a contact area between countries, nations and cultures. Contemporary European borders reflect the colourful history of an old continent. They are predominantely functional markers: they represent the political and juridical delimitation of territories, they mark economic barriers and show their defensive nature and reveal the extent of cultural contact. As a result of European integration processes, the nature of political borders has changed: instead of division, their integration role is brought to the fore. A united Europe is nevertheless still not a borderless Europe! The borders within the »Schengen-area« have retained their political and administrative functions, it is just that the customs and security checks at the borders have been removed. During the period of European integration, borderlines were stabilized in accordance with the 1974 Helsinki Agreement. But despite this we can still observe ongoing changes to state borders, particularly in areas of conflict such as the Balkan peninsula. It seems after all that the process of demarcation

  15. Enhancement of plaque removal efficacy by tooth brushing with baking soda dentifrices: results of five clinical studies.

    Science.gov (United States)

    Putt, Mark S; Milleman, Kimberly R; Ghassemi, Annahita; Vorwerk, Linda M; Hooper, William J; Soparkar, Pramod M; Winston, Anthony E; Proskin, Howard M

    2008-01-01

    An earlier clinical study demonstrated that brushing with a commercial Arm & Hammer dentifrice containing baking soda physically removed significantly more plaque than brushing with either of two commercial dentifrices which did not contain baking soda. However, little has been done to confirm these results and to compare baking soda-containing dentifrices with more recently commercialized non-baking soda dentifrice formulations. The objective of this study was to compare commercial dentifrices containing 20% to 65% baking soda and commercial dentifrices without baking soda in enhancing plaque removal efficacy of tooth brushing. Five randomized, controlled, blinded, crossover clinical studies were performed among healthy adult volunteers who provided informed consent. After approximately 24 hours without oral hygiene, subjects with sufficient plaque were enrolled in the study phase. Plaque was scored before and after supervised brushing for one minute using the Turesky, et al. modification of the Quigley-Hein Plaque Index at six sites per tooth according to Soparkar's modification as described by Lobene, et al. In each study, wash-out periods with a regular dentifrice not evaluated in the study separated each product treatment. In all studies, every dentifrice exhibited a significant (p baking soda dentifrices resulted in statistically greater (p baking soda. Results on other tooth surfaces, such as facial, lingual, proximal, and gingival surfaces also demonstrated statistically greater (p baking soda-containing dentifrices as compared to the baking soda-free dentifrices. In three of the studies comparing different levels of baking soda, brushing with dentifrices with higher concentrations of baking soda consistently removed numerically more plaque than those containing lower levels. In one of these three studies, the difference in plaque removal between the baking soda dentifrices reached statistical significance. The results suggest a positive relationship

  16. Why Sociology Is Silent Concerning Borders

    Directory of Open Access Journals (Sweden)

    S.E. Nikolov

    2015-08-01

    Full Text Available Border in sociological sense means a barrier that separates social groups, strata, their values, and the difference between ways of life between particular social groups. Such groups may be separated by many dividing lines, or borders: social/living conditions, opportunities/prospects, legal rights/customs, viewpoints, and so on. Sometimes mobility does not permit other than individual, or small-group, crossing of these borders. It seems really strange why border topic is almost completely absent from the sociology. It is so pertinent to the fate and shaping of various social groups, depending from the location of the border. We think of a boundary whenever we think of an entity demarcated from its surroundings. Events, too, have boundaries – temporal ones: their beginning, climax, final. All our lives are bounded in the continuum between our births and our deaths. A philosopher would imply also that even imaginary, abstract entities, such as concepts or layouts, have boundaries of their own. One may say that condition for all this boundary/border talk is coherent, and whether it reproduces the world around us’ structure, or the organizing activity of our intellect, are matters of deep philosophical controversy. Borders are difficult to disappear totally even within the European Union, providing some obstacles to the freedom of movement to those left still outside the Schengen agreement.

  17. The resurgence of cultural borders in international finance during the financial crisis: Evidence from Eurozone cross-border depositing

    NARCIS (Netherlands)

    Kleimeier, S.; Sander, H.; Heuchemer, S.

    2014-01-01

    In this paper, we demonstrate that cultural borders in international finance resurge during financial crises. To investigate the role of cultural borders during both tranquil and crisis periods, we employ a unique data set that focuses on Eurozone cross-border depositing in a gravity-model

  18. Synthesis and conformational characterization of functional di-block copolymer brushes for microarray technology

    Energy Technology Data Exchange (ETDEWEB)

    Di Carlo, Gabriele; Damin, Francesco [Institute of Chemistry of Molecular Recognition, National Research Council of Italy, Via M. Bianco 9, 20131 Milano (Italy); Armelao, Lidia [ISTM-CNR and INSTM, Department of Chemistry, University of Padova, Via F. Marzolo 1, 35131 Padova (Italy); Maccato, Chiara [Department of Chemistry and INSTM, University of Padova, Via F. Marzolo 1, 35131 Padova (Italy); Unlu, Selim [Department of Electrical and Computer Engineering, Boston University, St. Mary Street 8, Boston, MA 02215 (United States); Department of Biomedical Engineering, Boston University, St. Mary Street 8, Boston, MA 02215 (United States); Spuhler, Philipp S. [Department of Biomedical Engineering, Boston University, St. Mary Street 8, Boston, MA 02215 (United States); Chiari, Marcella, E-mail: marcella.chiari@icrm.cnr.it [Institute of Chemistry of Molecular Recognition, National Research Council of Italy, Via M. Bianco 9, 20131 Milano (Italy)

    2012-02-01

    Surface initiated polymerization (SIP) coupled with reversible addition-fragmentation chain transfer polymerization (RAFT) was used to functionalize microarray glass slides with block polymer brushes. N,N-dimethylacrylamide (DMA) and N-acryloyloxysuccinimide (NAS) (graft-poly[DMA-b-(DMA-co-NAS)]) brushes, with di-block architecture, were prepared from a novel RAFT chain transfer agent bearing a silanating moiety (RAFT silane) directly anchored onto the glass surfaces. Conformational characterization of the coatings was performed by Self Spectral Interference Fluorescence Microscopy (SSFM), an innovative technique that describes the location of a fluorescent DNA molecule relative to a surface with sub-nanometer accuracy. X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscopy (SEM) were used to characterize the coatings composition and morphology.

  19. Synthesis and conformational characterization of functional di-block copolymer brushes for microarray technology

    International Nuclear Information System (INIS)

    Di Carlo, Gabriele; Damin, Francesco; Armelao, Lidia; Maccato, Chiara; Unlu, Selim; Spuhler, Philipp S.; Chiari, Marcella

    2012-01-01

    Surface initiated polymerization (SIP) coupled with reversible addition-fragmentation chain transfer polymerization (RAFT) was used to functionalize microarray glass slides with block polymer brushes. N,N-dimethylacrylamide (DMA) and N-acryloyloxysuccinimide (NAS) (graft-poly[DMA-b-(DMA-co-NAS)]) brushes, with di-block architecture, were prepared from a novel RAFT chain transfer agent bearing a silanating moiety (RAFT silane) directly anchored onto the glass surfaces. Conformational characterization of the coatings was performed by Self Spectral Interference Fluorescence Microscopy (SSFM), an innovative technique that describes the location of a fluorescent DNA molecule relative to a surface with sub-nanometer accuracy. X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscopy (SEM) were used to characterize the coatings composition and morphology.

  20. AFM imaging of functionalized carbon nanotubes on biological membranes

    International Nuclear Information System (INIS)

    Lamprecht, C; Danzberger, J; Rangl, M; Gruber, H J; Hinterdorfer, P; Kienberger, F; Ebner, A; Liashkovich, I; Neves, V; Heister, E; Coley, H M; McFadden, J; Flahaut, E

    2009-01-01

    Multifunctional carbon nanotubes are promising for biomedical applications as their nano-size, together with their physical stability, gives access into the cell and various cellular compartments including the nucleus. However, the direct and label-free detection of carbon nanotube uptake into cells is a challenging task. The atomic force microscope (AFM) is capable of resolving details of cellular surfaces at the nanometer scale and thus allows following of the docking of carbon nanotubes to biological membranes. Here we present topographical AFM images of non-covalently functionalized single walled (SWNT) and double walled carbon nanotubes (DWNT) immobilized on different biological membranes, such as plasma membranes and nuclear envelopes, as well as on a monolayer of avidin molecules. We were able to visualize DWNT on the nuclear membrane while at the same time resolving individual nuclear pore complexes. Furthermore, we succeeded in localizing individual SWNT at the border of incubated cells and in identifying bundles of DWNT on cell surfaces by AFM imaging.

  1. Beneficial Insect Borders Provide Northern Bobwhite Brood Habitat

    Science.gov (United States)

    Moorman, Christopher E.; Plush, Charles J.; Orr, David B.; Reberg-Horton, Chris

    2013-01-01

    Strips of fallow vegetation along cropland borders are an effective strategy for providing brood habitat for declining populations of upland game birds (Order: Galliformes), including northern bobwhite (Colinus virginianus), but fallow borders lack nectar-producing vegetation needed to sustain many beneficial insect populations (e.g., crop pest predators, parasitoids, and pollinator species). Planted borders that contain mixes of prairie flowers and grasses are designed to harbor more diverse arthropod communities, but the relative value of these borders as brood habitat is unknown. We used groups of six human-imprinted northern bobwhite chicks as a bioassay for comparing four different border treatments (planted native grass and prairie flowers, planted prairie flowers only, fallow vegetation, or mowed vegetation) as northern bobwhite brood habitat from June-August 2009 and 2010. All field border treatments were established around nine organic crop fields. Groups of chicks were led through borders for 30-min foraging trials and immediately euthanized, and eaten arthropods in crops and gizzards were measured to calculate a foraging rate for each border treatment. We estimated arthropod prey availability within each border treatment using a modified blower-vac to sample arthropods at the vegetation strata where chicks foraged. Foraging rate did not differ among border treatments in 2009 or 2010. Total arthropod prey densities calculated from blower-vac samples did not differ among border treatments in 2009 or 2010. Our results showed plant communities established to attract beneficial insects should maximize the biodiversity potential of field border establishment by providing habitat for beneficial insects and young upland game birds. PMID:24376759

  2. The combined effect of food-simulating solutions, brushing and staining on color stability of composite resins

    Science.gov (United States)

    Silva, Tânia Mara Da; Sales, Ana Luísa Leme Simões; Pucci, Cesar Rogerio; Borges, Alessandra Bühler; Torres, Carlos Rocha Gomes

    2017-01-01

    Abstract Objective: This study evaluated the effect of food-simulating media associated with brushing and coffee staining on color stability of different composite resins. Materials and methods: Eighty specimens were prepared for each composite: Grandio SO (Voco), Amaris (Voco), Filtek Z350XT (3M/ESPE), Filtek P90 (3M/ESPE). They were divided into four groups according to food-simulating media for 7 days: artificial saliva (control), heptane, citric acid and ethanol. The composite surface was submitted to 10,950 brushing cycles (200 g load) in an automatic toothbrushing machine. The specimens were darkened with coffee solution at 37 °C for 24 h. After each treatment, color measurements were assessed by spectrophotometry, using CIE L*a*b* system. The overall color change (ΔE) was determined for each specimen at baseline (C1) and after the treatments (food-simulating media immersion/C2, brushing/C3 and dye solution/C4). Data were analyzed by two-way repeated measures ANOVA and Tukey’s tests (p composites (p = .001), time (p = .001) and chemical degradation (p = .002). The mean of ΔE for composites were: Z350XT (5.39)a, Amaris (3.89)b, Grandio (3.75)bc, P90 (3.36)c. According to food-simulating media: heptane (4.41)a, citric acid (4.24)a, ethanol (4.02)ab, artificial saliva (3.76)b. For the treatments: dye solution (4.53)a, brushing (4.26)a, after food-simulating media (3.52)b. Conclusions: The composite resin Filtek Z350XT showed significantly higher staining than all other composite resin tested. The immersion in heptane and citric acid produced the highest color alteration than other food-simulating media. The exposure of samples to brushing protocols and darkening in coffee solution resulted in significant color alteration of the composite resins. PMID:28642926

  3. Cross-border cooperation potential in fostering redevelopment of degraded border areas - a case study approach.

    Science.gov (United States)

    Alexandre Castanho, Rui; Ramírez, Beatriz; Loures, Luis; Fernández-Pozo, Luis; Cabezas, José

    2017-04-01

    Border interactions have reached unprecedented levels in recent decades, not only due to their potential for territorial integration but also considering their role in supranational processes, such as landscape reclamation, infrastructure development and land use planning on European territory. In this scenario, successful examples related to the redevelopment of degraded areas have been showing positive impacts at several levels, such as the social, economic, environmental and aesthetic ones which have ultimately related this process, positively, to sustainability issues. However, concerning to border areas, and due to their inherent legislative and bureaucratic conflicts, the intervention in these areas is more complex. Still, and taking into account previously developed projects and strategies of cross-border cooperation (CBC) in European territory it is possible to identified that the definition of common master plans and common objectives are critical issues to achieve the desired territorial success. Additionally, recent studies have put forward some noteworthy ideas highlighting that it is possible to establish a positive correlation between CBC processes and an increasing redevelopment of degraded border areas, with special focus on the reclamation of derelict landscapes fostering soil reuse and redevelopment. The present research, throughout case study analysis at the Mediterranean level - considering case studies from Portugal, Spain, Monaco and Italy - which presents specific data on border landscape redevelopment, enables us to conclude that CBC processes have a positive influence on the potential redevelopment of degraded border areas, considering not only urban but also rural land. Furthermore, this paper presents data obtained through a public participation process which highlights that these areas present a greater potential for landscape reclamation, fostering resource sustainability and sustainable growth. Keywords: Spatial planning; Land

  4. Karyotype analysis and sex determination in Australian Brush-turkeys (Alectura lathami.

    Directory of Open Access Journals (Sweden)

    Madison T Ortega

    Full Text Available Sexual differentiation across taxa may be due to genetic sex determination (GSD and/or temperature sex determination (TSD. In many mammals, males are heterogametic (XY; whereas females are homogametic (XX. In most birds, the opposite is the case with females being heterogametic (ZW and males the homogametic sex (ZZ. Many reptile species lack sex chromosomes, and instead, sexual differentiation is influenced by temperature with specific temperatures promoting males or females varying across species possessing this form of sexual differentiation, although TSD has recently been shown to override GSD in Australian central beaded dragons (Pogona vitticeps. There has been speculation that Australian Brush-turkeys (Alectura lathami exhibit TSD alone and/or in combination with GSD. Thus, we sought to determine if this species possesses sex chromosomes. Blood was collected from one sexually mature female and two sexually mature males residing at Sylvan Heights Bird Park (SHBP and shipped for karyotype analysis. Karyotype analysis revealed that contrary to speculation, Australian Brush-turkeys possess the classic avian ZW/ZZ sex chromosomes. It remains a possibility that a biased primary sex ratio of Australian Brush-turkeys might be influenced by maternal condition prior to ovulation that result in her laying predominantly Z- or W-bearing eggs and/or sex-biased mortality due to higher sensitivity of one sex in environmental conditions. A better understanding of how maternal and extrinsic factors might differentially modulate ovulation of Z- or W-bearing eggs and hatching of developing chicks possessing ZW or ZZ sex chromosomes could be essential in conservation strategies used to save endangered members of Megapodiidae.

  5. Effect of the US-Mexico border region in cardiovascular mortality: ecological time trend analysis of Mexican border and non-border municipalities from 1998 to 2012

    Directory of Open Access Journals (Sweden)

    Gabriel Anaya

    2017-05-01

    Full Text Available Abstract Background An array of risk factors has been associated with cardiovascular diseases, and developing nations are becoming disproportionately affected by such diseases. Cardiovascular diseases have been reported to be highly prevalent in the Mexican population, but local mortality data is poor. The Mexican side of the US-Mexico border has a culture that is closely related to a developed nation and therefore may share the same risk factors of cardiovascular diseases. We wanted to explore if there was higher cardiovascular mortality in the border region of Mexico compared to the rest of the nation. Methods We conducted a population based cross-sectional time series analysis to estimate the effects of education, insurance and municipal size in Mexican border (n = 38 and non-border municipalities (n = 2360 and its association with cardiovascular age-adjusted mortality rates between the years 1998–2012. We used a mixed effect linear model with random effect estimation and repeated measurements to compare the main outcome variable (mortality rate, the covariates (education, insurance and population size and the geographic delimiter (border/non-border. Results Mortality due to cardiovascular disease was consistently higher in the municipalities along the US-Mexico border, showing a difference of 78 · 5 (95% CI 58 · 7-98 · 3, p < 0 · 001 more cardiovascular deaths after adjusting for covariates. Larger municipal size and higher education levels showed a reduction in cardiovascular mortality of 12 · 6 (95% CI 11 · 4-13 · 8, p < 0 · 001 deaths and 8 · 6 (95% CI 5 · 5-11 · 8, p < 0 · 001 deaths respectively. Insurance coverage showed an increase in cardiovascular mortality of 3 · 6 (95% CI 3 · 1-4 · 0, p < 0 · 001 deaths per decile point increase. There was an increase in cardiovascular mortality of 0 · 3 (95% CI −0 · 001-0 · 6

  6. Numerical simulation of flow in Brush Creek Valley, Colorado

    International Nuclear Information System (INIS)

    Leone, J.M. Jr.; Lee, R.L.

    1987-06-01

    In this paper, we present some results from our three-dimensional, non-hydrostatic, finite element model applied to simulations of flow in Brush Creek Valley. These simulations are not intended to reproduce any particular experiment, but rather are to evaluate the qualitative performance of the model, to explore the major difficulties involved, and to begin sensitivity studies of the flows of interest. 2 refs., 11 figs

  7. Border region studies

    DEFF Research Database (Denmark)

    Makkonen, Teemu; Williams, Allan

    2016-01-01

    The contemporary conditions of academic capitalism exert pressures on researchers to avoid ‘peripheral’ journals and ‘unfashionable’ topics. Here an attempt is made to shed light onto the structure of one such ‘offbeat’ field, namely ‘border region studies’, by discussing its geographical...... distribution, key themes, significance and impact. The review suggests that border region studies can be considered a significant and important ‘branch’ of regional studies, which accounts for a small but increasing proportion of regional studies research particularly in Europe and North America. Four main...

  8. The structure of borders in a small world.

    Science.gov (United States)

    Thiemann, Christian; Theis, Fabian; Grady, Daniel; Brune, Rafael; Brockmann, Dirk

    2010-11-18

    Territorial subdivisions and geographic borders are essential for understanding phenomena in sociology, political science, history, and economics. They influence the interregional flow of information and cross-border trade and affect the diffusion of innovation and technology. However, it is unclear if existing administrative subdivisions that typically evolved decades ago still reflect the most plausible organizational structure of today. The complexity of modern human communication, the ease of long-distance movement, and increased interaction across political borders complicate the operational definition and assessment of geographic borders that optimally reflect the multi-scale nature of today's human connectivity patterns. What border structures emerge directly from the interplay of scales in human interactions is an open question. Based on a massive proxy dataset, we analyze a multi-scale human mobility network and compute effective geographic borders inherent to human mobility patterns in the United States. We propose two computational techniques for extracting these borders and for quantifying their strength. We find that effective borders only partially overlap with existing administrative borders, and show that some of the strongest mobility borders exist in unexpected regions. We show that the observed structures cannot be generated by gravity models for human traffic. Finally, we introduce the concept of link significance that clarifies the observed structure of effective borders. Our approach represents a novel type of quantitative, comparative analysis framework for spatially embedded multi-scale interaction networks in general and may yield important insight into a multitude of spatiotemporal phenomena generated by human activity.

  9. Clinical evaluation of an ionic tooth brush on oral hygiene status, gingival status, and microbial parameter

    Directory of Open Access Journals (Sweden)

    Deshmukh J

    2006-01-01

    Full Text Available It has long been recognised that the presence of dental plaque leads to gingivitis and periodontal disease, as well as dental caries. Today tooth brushing is the most widely accepted method of removing plaque. Hence this present clinical study was undertaken to evaluate the effectiveness of an ionic toothbrush on oral hygiene status. For this study, 20 dental students in the age group of 18-20 years were included. All the subjects after undergoing dental prophylaxis were then provided with ionic toothbrushes, either active (equipped with lithium battery or inactive (without lithium battery. Plaque index and gingival bleeding index were examined at 7th, 14th, and 21st day. Microbial assessment was done for detection of colony forming units (CFU from the plaque samples which were collected on 0 day and 21st day, both before brushing and after brushing. Results shown a significant reduction in all the parameters and the reduction was more significant in active and inactive ionic toothbrush users. It was concluded that both active and inactive ionic toothbrushes reduced the plaque index and gingival bleeding index scores significantly and active ionic tooth brushes were more effective as compared to inactive ionic toothbrushes. There was no soft tissue trauma following the use of both type of toothbrushes, which showed that ionic toothbrushes were equally safe for regular long-term use.

  10. Controlled growth of protein resistant PHEMA brushes via S-RAFT polymerization

    Czech Academy of Sciences Publication Activity Database

    Zamfir, M.; Rodriguez-Emmenegger, Cesar; Bauer, S.; Barner, L.; Rosenhahn, A.; Barner-Kowollik, C.

    2013-01-01

    Roč. 1, č. 44 (2013), s. 6027-6034 ISSN 2050-750X R&D Projects: GA ČR GAP205/12/1702; GA ČR GAP106/12/1451 Institutional support: RVO:61389013 Keywords : surface RAFT * polymer brushes * antifouling Subject RIV: CD - Macromolecular Chemistry

  11. Synthesis of novel glycopolymer brushes via a combination of RAFT-mediated polymerisation and ATRP

    Directory of Open Access Journals (Sweden)

    Eric T.A. van den Dungen

    2011-03-01

    Full Text Available Glycopolymers (synthetic sugar-containing polymers have become increasingly attractive to polymer chemists because of their role as biomimetic analogues and their potential for commercial applications. Glycopolymers of different structures confer high hydrophilicity and water solubility and can therefore be used for specialised applications, such as artificial materials for a number of biological, pharmaceutical and biomedical uses. The synthesis and characterisation of a series of novel glycopolymer brushes, namely poly(2-(2-bromoisobutyryloxy ethyl methacrylate-g-poly(methyl 6-O-methacryloyl-α-D-glucoside (P(BIEM-g-P(6-O-MMAGIc, poly(2-(2-bromoisobutyryloxy ethyl methacrylate-co-methyl methacrylate-g-poly(methyl 6-O-methacryloyl-α-D-glucoside P(BIEM-co-MMA-g-P(6-O-MMAGIc, poly(2-(2-bromoisobutyryloxy ethyl methacrylate-b-methyl methacrylate-g-poly(methyl 6-O-methacryloyl-α-D-glucoside P(BIEM-b-MMA-g-P(6-O-MMAGIc and poly(4-vinylbenzyl chloride-alt-maleic anhydride-g-poly(methyl 6-O-methacryloyl-α-D-glucoside (P(Sd-alt-MAnh-g-P(6-O-MMAGIc are described in this paper. Reversible addition-fragmentation chain transfer (RAFT-mediated polymerisation was used to synthesise four well-defined atom transfer radical polymerisation (ATRP macroinitiators (the backbone of the glycopolymer brushes. These ATRP macroinitiators were subsequently used in the ‘grafting from’ approach (in which side chains are grown from the backbone to prepare high molar mass and low polydispersity index glycopolymer brushes with different grafting densities along the backbone. The number average molar mass of the glycopolymer brushes was determined using size exclusion chromatography with a multi-angle laser light

  12. Introduction: Borders in Translation and Intercultural Communication

    Directory of Open Access Journals (Sweden)

    Jonathan Evans

    2017-09-01

    Full Text Available The introduction to this special issue discusses the notion of border and its position in current scholarship in translation studies and intercultural communication. It then analyses ways in which borders can be useful for thinking, focusing particularly on Walter Mignolo’s notion of “border thinking”. It reviews how borders are viewed in both translation studies and intercultural communication and offers some possible directions for future research before introducing the papers in this special issue.

  13. Extreme delta brush: a unique EEG pattern in adults with anti-NMDA receptor encephalitis.

    Science.gov (United States)

    Schmitt, Sarah E; Pargeon, Kimberly; Frechette, Eric S; Hirsch, Lawrence J; Dalmau, Josep; Friedman, Daniel

    2012-09-11

    To determine continuous EEG (cEEG) patterns that may be unique to anti-NMDA receptor (NMDAR) encephalitis in a series of adult patients with this disorder. We evaluated the clinical and EEG data of 23 hospitalized adult patients with anti-NMDAR encephalitis who underwent cEEG monitoring between January 2005 and February 2011 at 2 large academic medical centers. Twenty-three patients with anti-NMDAR encephalitis underwent a median of 7 (range 1-123) days of cEEG monitoring. The median length of hospitalization was 44 (range 2-200) days. Personality or behavioral changes (100%), movement disorders (82.6%), and seizures (78.3%) were the most common symptoms. Seven of 23 patients (30.4%) had a unique electrographic pattern, which we named "extreme delta brush" because of its resemblance to waveforms seen in premature infants. The presence of extreme delta brush was associated with a more prolonged hospitalization (mean 128.3 ± 47.5 vs 43.2 ± 39.0 days, p = 0.008) and increased days of cEEG monitoring (mean 27.6 ± 42.3 vs 6.2 ± 5.6 days, p = 0.012). The modified Rankin Scale score showed a trend toward worse scores in patients with the extreme delta brush pattern (mean 4.0 ± 0.8 vs 3.1 ± 1.1, p = 0.089). Extreme delta brush is a novel EEG finding seen in many patients with anti-NMDAR encephalitis. The presence of this pattern is associated with a more prolonged illness. Although the specificity of this pattern is unclear, its presence should raise consideration of this syndrome.

  14. Regulatory signals for intestinal amino acid transporters and peptidases

    International Nuclear Information System (INIS)

    Ferraris, R.P.; Kwan, W.W.; Diamond, J.

    1988-01-01

    Dietary protein ultimately regulates many processes involved in protein digestion, but it is often unclear whether proteins themselves, peptides, or amino acids (AAs) are the proximate regulatory signal. Hence the authors compared several processes involved in protein digestion in mice adapted to one of three rations, identical except for containing 54% of either casein, a partial hydrolysate of casein, or a free AA mixture simulating a complete hydrolysate of casein. The authors measured brush-border uptakes of seven AAs that variously serve as substrates for four AA transporters, and brush-border and cytosolic activities of four peptidases. The three rations yielded essentially the same AA uptake rates. Peptidase activities tended to be lower on the AA ration than on the protein ration. In other studies, all three rations yielded the same rates of brush-border peptide uptake; protein is only modestly more effective than AAs at inducing synthesis of pancreatic proteases; and, depending on the animal species, protein is either much less or much more effective than AAs at stimulating release of cholecystokinin and hence of pancreatic enzymes. Thus the regulators of each process involved in protein digestion are not necessarily that process's substrate

  15. Molecular aggregation states of poly{l_brace}2-(perfluorooctyl)ethyl acrylate{r_brace} polymer brush thin film analyzed by grazing incidence X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, H; Honda, K; Takahara, A [Graduate School of Engineering, Kyushu University, Nishi-ku, Fukuoka 819-0395 (Japan); Kobayashi, M [Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Morita, M [Fundamental Research Department, Chemical Division, Daikin Industries, Ltd., 1-1 Nishi Hitotsuya, Settsu-shi, Osaka 566-8585 (Japan); Masunaga, H; Sasaki, S; Takata, M [Japan Synchrotron Research Institute, Mikazuki Sayo, Hyogo 671-5198 (Japan); Sakata, O, E-mail: takahara@cstf.kyushu-u.ac.j [RIKEN Harima Institute, Mikazuki Sayo, Hyogo 671-5198 (Japan)

    2009-08-01

    Fluoropolymer brush with crystalline side chains was prepared by surface-initiated atom transfer radical polymerization of 2-(perfluorooctyl)ethyl acrylate (FA-C{sub 8}) from a flat silicon substrate. The crystallization and the molecular aggregation structures of polymer side chain at the outermost surface and internal region in the brush film were characterized by grazing incidence X-ray diffraction (GIXD) measurement using two different incident angles of X-ray. At the air interface of PFA-C{sub 8} brush film, the rod-like R{sub f} group was oriented perpendicular to the surface forming a hexagonal packing structure to reduce surface energy. In contrast, the oriented R{sub f} groups parallel to the substrate coexisted at the internal region in the brush. This unique depth dependence of crystalline state of the fluoropolymer brush was observed by surface-sensitive GIXD measurement.

  16. Helicobacter pylori in dental plaque; is it related to brushing frequency, plaque load and oral health status?

    Science.gov (United States)

    Chaudhry, Saima; Khan, Ayyaz Ali; Butt, Arshad Kamal; Idrees, Muhammad; Izhar, Mateen; Iqbal, Hafiz Aamer

    2011-10-01

    To determine the relation between presence of H. pylori in supra-gingival dental plaque with oral hygiene habits and oral health status of patients suffering from symptomatic dyspepsia. Descriptive study. The Department of Oral Health Sciences, Shaikh Zayed FPGMI, Lahore, from September 2008 to August 2009. One hundred and fifty dyspeptic subjects with dental plaque were enrolled. After recording brushing frequency, oral health status and plaque load, the supra-gingival dental plaque samples were collected by sterile curettes. Helicobacter pylori were detected in dental plaque samples through PCR assay. Presence of H. pylori in dental plaque was found to be 37.5% in the sample. Most of the subjects brushed once daily, had plaque index score of 1 and had fair to poor oral hygiene status. Approximately 35% of the individuals who brushed once or twice a day harbored the bacterium in their dental plaque. There was no difference between bacterial detection rates among different categories of plaque index and oral health status of the study subjects. Presence of H. pylori in dental plaque was found to be associated with neither brushing frequency nor with the plaque load nor with the oral health status of individuals suffering from symptomatic dyspepsia.

  17. U.S. Border Patrol Fiscal Year Statistics Southwest border sector deaths - FY 1998 through FY 2013

    Data.gov (United States)

    Department of Homeland Security — Southwest Border Sectors include: Del Rio, El Centro, El Paso, Laredo, Rio Grande Valley, San Diego, Tucson, Yuma Southwest Border Deaths By Fiscal Year (Oct. 1st...

  18. Network communities within and across borders

    OpenAIRE

    Cerina, Federica; Chessa, Alessandro; Pammolli, Fabio; Riccaboni, Massimo

    2014-01-01

    We investigate the impact of borders on the topology of spatially embedded networks. Indeed territorial subdivisions and geographical borders significantly hamper the geographical span of networks thus playing a key role in the formation of network communities. This is especially important in scientific and technological policy-making, highlighting the interplay between pressure for the internationalization to lead towards a global innovation system and the administrative borders imposed by t...

  19. The Hippo pathway controls border cell migration through distinct mechanisms in outer border cells and polar cells of the Drosophila ovary.

    Science.gov (United States)

    Lin, Tzu-Huai; Yeh, Tsung-Han; Wang, Tsu-Wei; Yu, Jenn-Yah

    2014-11-01

    The Hippo pathway is a key signaling cascade in controlling organ size. The core components of this pathway are two kinases, Hippo (Hpo) and Warts (Wts), and a transcriptional coactivator, Yorkie (Yki). Yes-associated protein (YAP, a Yki homolog in mammals) promotes epithelial-mesenchymal transition and cell migration in vitro. Here, we use border cells in the Drosophila ovary as a model to study Hippo pathway functions in cell migration in vivo. During oogenesis, polar cells secrete Unpaired (Upd), which activates JAK/STAT signaling of neighboring cells and specifies them into outer border cells. The outer border cells form a cluster with polar cells and undergo migration. We find that hpo and wts are required for migration of the border cell cluster. In outer border cells, overexpression of hpo disrupts polarization of the actin cytoskeleton and attenuates migration. In polar cells, knockdown of hpo and wts or overexpression of yki impairs border cell induction and disrupts migration. These manipulations in polar cells reduce JAK/STAT activity in outer border cells. Expression of upd-lacZ is increased and decreased in yki and hpo mutant polar cells, respectively. Furthermore, forced expression of upd in polar cells rescues defects of border cell induction and migration caused by wts knockdown. These results suggest that Yki negatively regulates border cell induction by inhibiting JAK/STAT signaling. Together, our data elucidate two distinct mechanisms of the Hippo pathway in controlling border cell migration: (1) in outer border cells, it regulates polarized distribution of the actin cytoskeleton; (2) in polar cells, it regulates upd expression to control border cell induction and migration. Copyright © 2014 by the Genetics Society of America.

  20. Interactions between Nanoparticles and Polymer Brushes: Molecular Dynamics Simulations and Self-consistent Field Theory Calculations

    Science.gov (United States)

    Cheng, Shengfeng; Wen, Chengyuan; Egorov, Sergei

    2015-03-01

    Molecular dynamics simulations and self-consistent field theory calculations are employed to study the interactions between a nanoparticle and a polymer brush at various densities of chains grafted to a plane. Simulations with both implicit and explicit solvent are performed. In either case the nanoparticle is loaded to the brush at a constant velocity. Then a series of simulations are performed to compute the force exerted on the nanoparticle that is fixed at various distances from the grafting plane. The potential of mean force is calculated and compared to the prediction based on a self-consistent field theory. Our simulations show that the explicit solvent leads to effects that are not captured in simulations with implicit solvent, indicating the importance of including explicit solvent in molecular simulations of such systems. Our results also demonstrate an interesting correlation between the force on the nanoparticle and the density profile of the brush. We gratefully acknowledge the support of NVIDIA Corporation with the donation of the Tesla K40 GPU used for this research.

  1. The Cosmopolitanization of the EU’s Borders?

    Directory of Open Access Journals (Sweden)

    Damian Spruce

    2007-08-01

    Full Text Available For centuries the political geography of Europe has been based around borders of its nation states. The ability of the nation state to control its territory has been essential to the practices of war and diplomacy, the legitimacy of governments, immigration policies and trade. But processes of globalization and EU integration have transformed the borders of the European nation state. While globalization theorists tend to posit an opening up of borders to global flows of capital, information and people, the changed nature of the border is itself often left unexamined and is assumed to have simply disappeared. But scholars and activists are now arguing that, rather than fading away, borders are proliferating in the globalized world and their functions spreading into many different areas of society. This article examines the transformation of the ‘classical’ border of the nation-state into its recent forms, using the work of theorists such as Balibar, Mezzadra, Rigo and Walters. It then examines how these theories have been applied in recent literature, and in particular Chris Rumford’s analysis of the European Neighbourhood policy and his argument that this represents a ‘cosmopolitanisation’ of European borders.

  2. The brush model - a new approach to numerical modeling of matrix diffusion in fractured clay stone

    International Nuclear Information System (INIS)

    Lege, T.; Shao, H.

    1998-01-01

    A special approach for numerical modeling of contaminant transport in fractured clay stone is presented. The rock matrix and the fractures are simulated with individual formulations for FE grids and transport, coupled into a single model. The capacity of the rock matrix to take up contaminants is taken into consideration with a discrete simulation of matrix diffusion. Thus, the natural process of retardation due to matrix diffusion can be better simulated than by a standard introduction of an empirical parameter into the transport equation. Transport in groundwater in fractured clay stone can be simulated using a model called a 'brush model'. The 'brush handle' is discretized by 2-D finite elements. Advective-dispersive transport in groundwater in the fractures is assumed. The contaminant diffuses into 1D finite elements perpendicular to the fractures, i.e., the 'bristles of the brush'. The conclusion is drawn that matrix diffusion is an important property of fractured clay stone for contaminant retardation. (author)

  3. Mate choice in Australian brush-turkeys Alectura lathami : a preliminary report

    NARCIS (Netherlands)

    Birks, S.

    1992-01-01

    Female brush-turkeys respond to several factors when choosing with whom they will mate and where they will lay their eggs. The most important factors seem to be mound condition (especially incubation stage and digging effort required), male presence at mounds (though not necessarily male quality),

  4. European Banks Straddling Borders: Risky or Rewarding?

    NARCIS (Netherlands)

    P. Duijm (Patty); D. Schoenmaker (Dirk)

    2017-01-01

    textabstractTheory suggests that cross-border banking is beneficial as long as there is a non-perfect correlation across country-specific risks. Using a unique hand-collected dataset with cross-border loans for the 61 largest European banks, we find that cross-border banking in general decreases

  5. Grafting of functional methacrylate polymer brushes by photoinduced SET-LRP

    Czech Academy of Sciences Publication Activity Database

    Vorobii, M.; Pop-Georgievski, Ognen; de los Santos Pereira, Andres; Kostina, N. Yu.; Jezorek, R.; Sedláková, Zdeňka; Percec, V.; Rodriguez-Emmenegger, C.

    2016-01-01

    Roč. 7, č. 45 (2016), s. 6934-6945 ISSN 1759-9954 R&D Projects: GA ČR(CZ) GJ15-09368Y Grant - others:OPPK(XE) CZ.2.16/3.1.00/21545 Program:OPPK Institutional support: RVO:61389013 Keywords : photo-induced polymerization * polymer brushes * spatial control Subject RIV: CD - Macromolecular Chemistry Impact factor: 5.375, year: 2016

  6. Factors Associated with Depression Among Mexican Americans Living in U.S.-Mexico Border and Non-Border Areas.

    Science.gov (United States)

    Vaeth, Patrice A C; Caetano, Raul; Mills, Britain A

    2016-08-01

    Factors associated with CES-D depression among Mexican Americans living on and off the U.S.-Mexico border are examined. Data are from two studies of Mexican American adults. The Border Survey conducted face-to-face interviews in urban U.S.-Mexico border counties of California, Arizona, New Mexico, and Texas (N = 1307). The non-border HABLAS survey conducted face-to-face interviews in Houston, Los Angeles, New York, Philadelphia, and Miami (N = 1288). Both surveys used a multistage cluster sample design with response rates of 67 and 76 %, respectively. The multivariate analysis showed that border residence and higher perceived neighborhood collective efficacy were protective for depression among men. Among men, lower education, unemployment, increased weekly drinking, and poor health status were associated with depression. Among women, alcohol-related problems and poorer health status were also associated with depression. Further examinations of how neighborhood perceptions vary by gender and how these perceptions influence the likelihood of depression are warranted.

  7. Tailored Poly(2-oxazoline) Polymer Brushes to Control Protein Adsorption and Cell Adhesion

    KAUST Repository

    Zhang, Ning

    2012-05-18

    POx bottle-brush brushes (BBBs) are synthesized by SIPGP of 2-isopropenyl-2-oxazoline and consecutive LCROP of 2-oxazolines on 3-aminopropyltrimethoxysilane-modified silicon substrates. The side chain hydrophilicity and polarity are varied. The impact of the chemical composition and architecture of the BBB upon protein (fibronectin) adsorption and endothelial cell adhesion are investigated and prove extremely low protein adsorption and cell adhesion on BBBs with hydrophilic side chains such as poly(2-methyl-2-oxazoline) and poly(2-ethyl-2-oxazoline). The influence of the POx side chain terminal function upon adsorption and adhesion is minor but the side chain length has a significant effect on bioadsorption. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Tailored Poly(2-oxazoline) Polymer Brushes to Control Protein Adsorption and Cell Adhesion

    KAUST Repository

    Zhang, Ning; Pompe, Tilo; Amin, Ihsan; Luxenhofer, Robert; Werner, Carsten; Jordan, Rainer

    2012-01-01

    POx bottle-brush brushes (BBBs) are synthesized by SIPGP of 2-isopropenyl-2-oxazoline and consecutive LCROP of 2-oxazolines on 3-aminopropyltrimethoxysilane-modified silicon substrates. The side chain hydrophilicity and polarity are varied. The impact of the chemical composition and architecture of the BBB upon protein (fibronectin) adsorption and endothelial cell adhesion are investigated and prove extremely low protein adsorption and cell adhesion on BBBs with hydrophilic side chains such as poly(2-methyl-2-oxazoline) and poly(2-ethyl-2-oxazoline). The influence of the POx side chain terminal function upon adsorption and adhesion is minor but the side chain length has a significant effect on bioadsorption. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Endobiliary brush biopsy: Intra- and interobserver variation in cytological evaluation of brushings from bile duct strictures

    DEFF Research Database (Denmark)

    Adamsen, S; Olsen, M; Jendresen, MB

    2006-01-01

    OBJECTIVE: Obtaining cytological specimens by wire-guided endobiliary brushing at the time of endoscopic retrograde cholangiopancreatography (ERCP) is a convenient way to reach a diagnosis. Sensitivity for malignant disease is generally around 50% and specificity around 100%. The present study...... was designed to assess the reproducibility of the cytological examination. MATERIAL AND METHODS: Samples were obtained from 55 consecutive patients with biliary duct strictures that eventually turned out to be caused by malignant disease in 41 patients (73%). The cytology specimens were evaluated twice...... in different random order with an interval of at least 4 months by two pathologists blinded to the final diagnoses. Suitability for diagnosis (suitable, suboptimal or unsuitable) and cytologic diagnosis (benign, atypical, suspicious for malignancy and malignant cells) were registered. Kappa analysis...

  10. Competitive implications of cross-border banking

    OpenAIRE

    Claessens, Stijn

    2006-01-01

    This paper reviews the recent literature on cross-border banking, with a focus on policy implications. Cross-border banking has increased sharply in recent decades, particularly in the form of entry, and has affected the development of financial systems, access to financial services, and stability. Reviewing the empirical literature, the author finds much, although not uniform, evidence that cross-border banking supports the development of an efficient and stable financial system that offers ...

  11. Two Randomized Clinical Studies to Confirm Differential Plaque Removal by Sodium Bicarbonate Dentifrices in a Single Timed Brushing Model.

    Science.gov (United States)

    Mason, Stephen; Karwal, Ritu; Bosma, Mary Lynn

    2017-09-01

    This study evaluated and compared plaque removal efficacy of commercially available dentifrices containing sodium bicarbonate (NaHCO3) to those without NaHCO3 in a single timed brushing clinical study model. Two randomized, examiner-blind, three-period, three-treatment, crossover studies were performed in adults with a mean Turesky modification of the Quigley-Hein Plaque Index (TPI) score of = 2.00. In Study 1, 60 subjects were randomized to commercially available dentifrices containing: (i) 67% NaHCO3 plus 1425 ppm fluoride (F) as sodium fluoride (NaF); (ii) 45% NaHCO3 plus 1425 ppm F as NaF; or (iii) 0% NaHCO3 plus silica and 1450 ppm F as NaF. In Study 2, 55 subjects were randomized to commercially available dentifrices containing: (i) 67% NaHCO3 plus 1425 ppm F as NaF; (ii) 0% NaHCO3 plus silica and 1400 ppm F as amine F/stannous F; or (iii) 0% NaHCO3 plus chlorhexidine/aluminum lactate and silica with 1360 ppm F as aluminum F. In both studies, subjects brushed their teeth for one timed minute under supervised conditions. Plaque was assessed pre- and post-brushing according to a six-site modification of the TPI. Mean TPI score was analyzed using an analysis of covariance model with treatment and study period as fixed effects, subject as a random variable, and pre-brushing score as a covariate. In both studies, mean TPI score decreased in all groups post-brushing compared with pre-brushing. In Study 1, statistically significant improvements in mean TPI score were reported with the 67% and 45% NaHCO3 dentifrices compared with the 0% NaHCO3 dentifrice (p = 0.0003 and p = 0.0005, respectively). In Study 2, improvements in mean TPI score were statistically significantly greater with the 67% NaHCO3 dentifrice compared with both 0% NaHCO3 dentifrices (p < 0.0001 for both comparisons). All dentifrices were generally well tolerated. A single timed brushing with commercially available dentifrices containing 67% or 45% NaHCO3 exerted a significantly greater effect on

  12. Picking and Choosing the ‘Sovereign’Border

    DEFF Research Database (Denmark)

    Parker, Noel; Adler-Nissen, Rebecca

    2012-01-01

    We argue that the continued persistence of borders is an effect of their constitutive role for the many dimensions of a social particular. States cannot choose to have a border; but they can and do make choices amongst the materials available on the various planes of inscription for bordering. Fo...

  13. Measuring cross-border regional integration with composite indicators

    DEFF Research Database (Denmark)

    Makkonen, Teemu

    2016-01-01

    Earlier quantitative studies on cross-border regional integration processes have commonly neglected science, technology and innovation (STI) indicators: even the most notable example of a composite indicator approach to measuring cross-border regional integration, i.e. the Oresund index, lacks...... a sub-category for STI. Consequently, by ignoring cross-border innovation and knowledge flows, the Oresund integration index fails to take into account one of the most important drivers of economic growth in cross-border regions. Therefore, a new composite STI indicator (sub-category) was introduced......-border regions....

  14. Carrier-mediated transport of peptides by the kidney

    International Nuclear Information System (INIS)

    Skopicki, H.A.

    1988-01-01

    Small peptide transport was characterized to determine if: (1) Multiple carriers are present in the luminal membrane of renal proximal tubular cells; (2) Carrier-mediated peptide transport is limited by size; and (3) Gentamicin inhibits carrier-mediated reabsorption of peptides. Uptake of glycyl-[ 3 H]proline (Gly-Pro) into renal brush border membrane vesicles demonstrated a dual affinity carrier system. Whether multiple carriers are present was further investigated by characterizing the uptake of [ 3 H]pyroglutamyl-histidine. To determine if carrier-mediated transport of peptides is limited by size of the molecule, uptake of the hydrolytically resistant tripeptide, [ 3 H]pryroglutamyl-histidyl-tryptophan (pGlu-His-Trp), and tetrapeptide, [ 3 H]pyroglutamyl-histidyl-tryptophyl-serine (pGlu-His-Trp-Ser) were assessed. These data indicate: multiple carriers exist on the luminal membrane of renal proximal tubular cells for the transport of dipeptides, and tripeptide pGlu-His-Trp and the tetrapeptide pGlu-His-Trp-Ser are not taken up by a carrier-mediated mechanism, suggesting that the carrier may be limited by the size of the substrate

  15. Long-term follow-up of patients with a clinically benign extrahepatic biliary stenosis and K-ras mutation in endobiliary brush cytology

    NARCIS (Netherlands)

    van Heek, N. Tjarda; Rauws, Erik A. J.; Caspers, Eric; Drillenburg, Paul; Gouma, Dirk J.; Offerhaus, G. Johan A.

    2002-01-01

    Background. K-ras mutations in endobiliary brush cytology are an early event in carcinogenesis and justify a suspicion of malignancy in patients with extrahepatic biliary stenosis. However, K-ras mutations have been detected in specimens obtained by brushing of clinically benign extrahepatic biliary

  16. The role of immigration age on alcohol and drug use among border and non-border Mexican Americans.

    Science.gov (United States)

    Reingle, Jennifer M; Caetano, Raul; Mills, Britain A; Vaeth, Patrice A C

    2014-07-01

    To determine the age of immigration at which the marked increase in risk for alcohol- and drug-use problems in adulthood is observed among Mexican American adults residing in 2 distinct contexts: the U.S.-Mexico border, and cities not proximal to the border. We used 2 samples of Mexican American adults: specifically, 1,307 who resided along the U.S.-Mexico border, and 1,288 non-border adults who were interviewed as a part of the 2006 Hispanic Americans Baseline Alcohol Survey study. Survey logistic and Poisson regression methods were used to examine how immigration age during adolescence is related to alcohol- and drug-use behavior in adulthood. We found that participants who immigrate to the United States prior to age 14 have qualitatively different alcohol- and drug-related outcomes compared to those who immigrate later in life. Adults who immigrated at younger ages have alcohol- and drug-use patterns similar to those who were U.S.-born. Adults who immigrated at young ages and reside distal from the U.S.-Mexico border are at greater risk for alcohol and drug use than those who live in border contexts. Immigration from Mexico to the U.S. before age 14 results in alcohol- and drug-related behavior that mirrors the behavior of U.S.-born residents, and the alcohol- and drug-use effects were more pronounced among adults who did not reside proximal to the U.S.-Mexico border. Copyright © 2014 by the Research Society on Alcoholism.

  17. Decision Model for U.S.- Mexico Border Security Measures

    Science.gov (United States)

    2017-09-01

    missions that the I&A focuses on is, “border security, including narcotics smuggling, alien and human smuggling, and money laundering ...and money assigned to border security investments. 14. SUBJECT TERMS Department of Homeland Security (DHS), border security, U.S.–Mexico border...and money assigned to border security investments. vi THIS PAGE INTENTIONALLY LEFT BLANK vii TABLE OF CONTENTS I. INTRODUCTION

  18. Network communities within and across borders.

    Science.gov (United States)

    Cerina, Federica; Chessa, Alessandro; Pammolli, Fabio; Riccaboni, Massimo

    2014-04-01

    We investigate the impact of borders on the topology of spatially embedded networks. Indeed territorial subdivisions and geographical borders significantly hamper the geographical span of networks thus playing a key role in the formation of network communities. This is especially important in scientific and technological policy-making, highlighting the interplay between pressure for the internationalization to lead towards a global innovation system and the administrative borders imposed by the national and regional institutions. In this study we introduce an outreach index to quantify the impact of borders on the community structure and apply it to the case of the European and US patent co-inventors networks. We find that (a) the US connectivity decays as a power of distance, whereas we observe a faster exponential decay for Europe; (b) European network communities essentially correspond to nations and contiguous regions while US communities span multiple states across the whole country without any characteristic geographic scale. We confirm our findings by means of a set of simulations aimed at exploring the relationship between different patterns of cross-border community structures and the outreach index.

  19. Border Crossing/Entry Data - Boarder Crossing

    Data.gov (United States)

    Department of Transportation — Border Crossing/Entry Data provides summary statistics for incoming crossings at the U.S.-Canadian and the U.S.-Mexican border at the port level. Data are available...

  20. Nanocomposite Membrane via Magnetite Nanoparticle Assembly

    KAUST Repository

    Xie, Yihui

    2012-07-01

    Membrane technology is one of the most promising technologies for addressing the global water crisis as well as in many other applications. One of the drawbacks of current ultra- and nanofiltration membranes is the relatively broad pore size distribution. Block copolymer membranes with ultrahigh permeability and very regular pore sizes have been recently demonstrated with pores being formed by the supramolecular assembly of core/shell micelles. Our study aimed at developing an innovative and economically efficient alternative method to fabricate isoporous membrane by self-assembly of magnetic nanoparticle with a polystyrene shell, mimicking the behavior of block copolymer micelle. Fe3O4 nanoparticles of ~13 nm diameter were prepared by co-precipitation as cores. The initiator for ATRP was covalently bonded onto the surface of magnetic nanoparticles with two strategies. Then the surface initiated ATRP of styrene was carried out to functionalize nanoparticles with polystyrene through a “grafting from” method. Finally, the nanocomposite membrane was cast from 50 wt % Fe3O4@PS brush polymer solution in DMF via non solvent phase inversion. Microscopies reveal an asymmetric membrane with a dense thin layer on top of a porous sponge-like layer. This novel class of asymmetric membrane, based on the pure assembly of functionalized nanoparticles was prepared for the first time. The nanoparticles are well distributed however with no preferential order yet in the as-cast film.I would like to thank my committee chair and advisor, Prof. Suzana Nunes, and other committee members, Prof. Klaus-Viktor Peinemann and Prof. Gary Amy, for their guidance and support throughout the course of this research. My appreciation also goes to my colleagues in our group for useful discussions and suggestions. I also want to extend my gratitude to the staff from the KAUST Core Lab for Advanced Nanofabrication, Imaging and Characterization, especially Dr. Ali Reza Behzad, Dr. Rachid Sougrat, and