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

PubMed

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.

Sulfate-bicarbonate exchange in brush-border membranes from rat renal cortex

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pritchard, J.B.

1987-02-01

Under Na/sup +/-free conditions /sup 35/SO/sub 4//sup 2 -/ uptake by rat renal brush-border membrane (BBM) vesicles could be driven by imposition of a HCO/sup -//sub 3/ gradient (in greater than out). The initial rate of /sup 35/SO/sub 4//sup 2 -/ uptake was stimulated 10-fold, and peak overshoot exceeded equilibrium uptake by 2-3 times. Cl/sup -/, SCN/sup -/, NO/sub 3//sup -/, I/sup -/, and OH/sup -/ were able to substitute for HCO/sub 3//sup -/. Divalent anions, including /sup 35/SO/sub 4//sup 2 -/ itself, were less effective as counterions. HCO/sub 3//sup -/-SO/sub 4//sup 2 -/ exchange was cis-inhibited by disulfonic stilbenes,more » ((SITS)(DIDS)), phloretin, Hg, and S/sub 2/O/sub 3//sup 2 -/. HCO/sub 3//sup -/-driven /sup 35/SO/sub 4//sup 2 -/ uptake was saturable, with an apparent K/sub m/ of 0.4 mM for SO/sub 4//sup 2 -/. Simultaneous imposition of Na/sup +/ and HCO/sub 3//sup -/ gradients produced approximately additive stimulation of /sup 35/SO/sub 4//sup 2 -/ uptake. The HCO/sub 3//sup -/-driven component of /sup 35/SO/sub 4//sup 2 -/ uptake, but not the component driven by Na/sup +/, was inhibited by SITS. Finally, Na/sup +/-driven SO/sub 4//sup 2 -/ accumulation could be reduced by imposing an out greater than in HCO/sub 3//sup +/ gradient, conditions accelerating exchange driven SO/sub 4//sup 2 -/ efflux. These findings indicate the presence of separate Na/sup +/-SO/sub 4//sup 2 -/ cotransport and SO /sub 4//sup 2 -/-anion exchange pathways in the same BBM vesicles.« less

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

PubMed Central

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

2014-01-01

Background/Aims 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. Methods 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. Results 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. Conclusions 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. PMID:24297041

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.

PubMed

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.

[Effect of natural or synthetic detergents on the transport of D-glucose in the membranes of vesicles of the brush border of the intestine of the rabbit].

PubMed

Favilli, F; Iantomasi, T; Stio, M; Treves, C; Vanni, P; Vincenzini, M T

1988-01-01

We describe here the effects of natural and synthetic detergents on the D-glucose transport into brush-border membranes of vesicles of rabbit's intestine. Two synthetic detergents: Triton X-100 and dodecyltrimethylammonium bromide have been found very strong inhibitors (more than 50 p. 100 of inhibition of maximal D-glucose uptake). Kinetic studies showed that these detergents behaved as mixed type inhibitors. The Na+-dependent transport of amino acids (aspartic acid, lysine, phenylalanine) is only poorly affected by dodecyltrimethylammonium bromide, while Triton X-100 inhibits unspecifically all the transport studied.

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

PubMed

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.

The mechanisms of brush border Na+/H+ exchanger activation by corticosteroids.

PubMed

Zallocchi, Marisa; Igarreta, Pilar; Calvo, Juan Carlos; Reboucas, Nancy Amaral; Damasco, María Christina

2003-02-01

Previously we showed that corticosterone and aldosterone increased proton fluxes in proximal tubule, by micropuncture and stationary microperfusion. Since the Na+/H+ exchanger is responsible for the main proximal proton secretion, we have now evaluated the effects aldosterone on Na+/H+ exchange activity in brush border vesicles. In order to evaluate the mechanism of action of glucocorticoids and mineralocorticoids, we studied the comparative effects of corticosterone and aldosterone on the abundance of NHE3 and NHE2 isoforms. We isolated renal brush border vesicles from rats by differential centrifugation in sham-operated, adrenalectomized, and adrenalectomized-aldosterone treated (ADX + aldosterone) animals. We measured the kinetics of H+ transport in response to increasing concentrations of Sodium Gluconate by fluorimetry using acridine orange. For Na+/H+ exchanger abundance we used Western blot analysis of brush border proteins in the above groups and in adrenalectomized-corticosterone treated rats. The Vmax in adrenalectomized animals was 22,162+/-1828 fluorescence units/min; in sham animals, 37,020+/-2722; and in ADX + aldosterone, 42,344+/-3044 (p<0.01 adrenalectomized vs others). No differences in Km were observed. Adrenalectomy decreased NHE3 abundance over Sham by 32% without modifying NHE2. Corticosterone-replacement enhanced NHE3 abundance by 76% and failed to increase NHE2. Aldosterone enhanced NHE2 abundance by 75% and did not increase NHE3. Mineralocorticoids enhance Na+/H+ exchange activity by increasing NHE2 abundance; glucocorticoids, by increasing NHE3 abundance.

Restoring effect of selenium on the molecular content, structure and fluidity of diabetic rat kidney brush border cell membrane.

PubMed

Gurbanov, Rafig; Bilgin, Mehmet; Severcan, Feride

2016-04-01

Diabetic kidney disease (DKD) is a dominant factor standing for kidney impairments during diabetes. In this study, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy was used to disclose the diabetes-induced structural changes in the kidney and evaluate the effects of selenium on diabetes. The increase in the area of the olefinic band indicated increased amount of lipid peroxidation end products in diabetic kidney brush border cell membrane. Moreover, saturated lipid content of this cell membrane considerably diminished. DKD was found to disrupt lipid order and cause a decrease in membrane dynamics. However, the administration of selenium at low and medium doses was shown to improve these conditions by changing the lipid contents toward control values, restoring the ordered structure of the lipids and membrane dynamics. Curve-fitting and artificial neural network (ANN) analyses of secondary structures of proteins demonstrated a relative increase in α-helix and reduction in the β-sheet during diabetes in comparison to the control group, which were ameliorated following selenium treatment at low and medium doses. These findings were further confirmed by applying hierarchical cluster analysis (HCA) and principal component analysis (PCA). A clear separation of the experimental groups was obtained with high heterogeneity in the lipid and protein regions. These chemometric analyses showed that the low and medium doses of selenium-treated diabetic groups are successfully segregated from the diabetic group and clustered closer to the control. The study suggests that medium and, more predominantly, low-dose selenium treatment can be efficient in eliminating diabetes-induced structural alterations. Copyright © 2016 Elsevier B.V. All rights reserved

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

PubMed

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.

Exploring the Midgut Transcriptome and Brush Border Membrane Vesicle Proteome of the Rice Stem Borer, Chilo suppressalis (Walker)

PubMed Central

Peng, Chuanhua; Wang, Xiaoping; Li, Fei; Lin, Yongjun

2012-01-01

The rice stem borer, Chilo suppressalis (Walker) (Lepidoptera: Pyralidae), is one of the most detrimental pests affecting rice crops. The use of Bacillus thuringiensis (Bt) toxins has been explored as a means to control this pest, but the potential for C. suppressalis to develop resistance to Bt toxins makes this approach problematic. Few C. suppressalis gene sequences are known, which makes in-depth study of gene function difficult. Herein, we sequenced the midgut transcriptome of the rice stem borer. In total, 37,040 contigs were obtained, with a mean size of 497 bp. As expected, the transcripts of C. suppressalis shared high similarity with arthropod genes. Gene ontology and KEGG analysis were used to classify the gene functions in C. suppressalis. Using the midgut transcriptome data, we conducted a proteome analysis to identify proteins expressed abundantly in the brush border membrane vesicles (BBMV). Of the 100 top abundant proteins that were excised and subjected to mass spectrometry analysis, 74 share high similarity with known proteins. Among these proteins, Western blot analysis showed that Aminopeptidase N and EH domain-containing protein have the binding activities with Bt-toxin Cry1Ac. These data provide invaluable information about the gene sequences of C. suppressalis and the proteins that bind with Cry1Ac. PMID:22666467

Bacillus thuringiensis delta-endotoxin binding to brush border membrane vesicles of rice stem borers.

PubMed

Alcantara, Edwin P; Aguda, Remedios M; Curtiss, April; Dean, Donald H; Cohen, Michael B

2004-04-01

The receptor binding step in the molecular mode of action of five delta-endotoxins (Cry1Ab, Cry1Ac, Cry1C, Cry2A, and Cry9C) from Bacillus thuringiensis was examined to find toxins with different receptor sites in the midgut of the striped stem borer (SSB) Chilo suppressalis (Walker) and yellow stem borer (YSB) Scirpophaga incertulas (Walker) (Lepidoptera: Pyralidae). Homologous competition assays were used to estimate binding affinities (K(com)) of (125)I-labelled toxins to brush border membrane vesicles (BBMV). The SSB BBMV affinities in decreasing order was: Cry1Ab = Cry1Ac > Cry9C > Cry2A > Cry1C. In YSB, the order of decreasing affinities was: Cry1Ac > Cry1Ab > Cry9C = Cry2A > Cry1C. The number of binding sites (B(max)) estimated by homologous competition binding among the Cry toxins did not affect toxin binding affinity (K(com)) to both insect midgut BBMVs. Results of the heterologous competition binding assays suggest that Cry1Ab and Cry1Ac compete for the same binding sites in SSB and YSB. Other toxins bind with weak (Cry1C, Cry2A) or no affinity (Cry9C) to Cry1Ab and Cry1Ac binding sites in both species. Cry2A had the lowest toxicity to 10-day-old SSB and Cry1Ab and Cry1Ac were the most toxic. Taken together, the results of this study show that Cry1Ab or Cry1Ac could be combined with either Cry1C, Cry2A, or Cry9C for more durable resistance in transgenic rice. Cry1Ab should not be used together with Cry1Ac because a mutation in one receptor site could diminish binding of both toxins. Copyright 2004 Wiley-Liss, Inc.

Induction of a Gradual, Reversible Morphogenesis of Its Host’s Epithelial Brush Border by Vibrio fischeri

PubMed Central

Lamarcq, Laurence H.; McFall-Ngai, Margaret J.

1998-01-01

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 β-actin probes did not show marked bacterium-induced increases in β-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. PMID:9453641

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

PubMed

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.

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

NASA Astrophysics Data System (ADS)

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.

Inhibition of gentamicin binding to rat renal brush-border membrane by megalin ligands and basic peptides.

PubMed

Nagai, Junya; Saito, Masaki; Adachi, Yoshinori; Yumoto, Ryoko; Takano, Mikihisa

2006-05-01

Our previous studies showed that coadministration of cytochrome c and a 20-residue basic peptide, N-WASP181-200 (NISHTKEKKKGKAKKKRLTK, pI=10.87) inhibits renal accumulation of gentamicin. In this study, we examined effects of ligands of megalin, an endocytic receptor involved in renal uptake of gentamicin, and basic peptides including N-WASP180-200 and its mutant peptides on gentamicin binding to isolated rat renal brush-border membrane (BBM). Gentamicin binding to BBM was inhibited by megalin ligands, basic peptide fragments of cytochrome c, and N-WASP181-200 in a concentration-dependent manner. Klotz plot analysis showed that N-WASP181-200 inhibited the binding of gentamicin in a competitive manner. By substituting glycines for lysines in N-WASP181-200 at positions 9 and 15, the inhibitory effect on gentamicin binding to BBM was reduced, which may be related to a decrease in the alpha-helix content in the peptide. Gentamicin binding to BBM treated with trypsin, in which megalin completely disappeared, was significantly but not completely decreased compared with the native BBM. In addition, treatment of BBM with trypsin led to a decrease in the inhibitory effect of N-WASP181-200 on gentamicin binding. These observations support that megalin ligands and basic peptides including N-WASP181-200 decrease renal accumulation of gentamicin by inhibiting its binding to BBM of proximal tubule cells, partly interacting with megalin. In addition, the alpha-helix conformation may play an important role in the inhibitory effect of N-WASP181-200 on the binding of gentamicin to BBM.

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

PubMed

Consonni, Sarah V; Brouwer, Patricia M; van Slobbe, Eleonora S; Bos, Johannes L

2014-01-01

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.

The PDZ Domain of the Guanine Nucleotide Exchange Factor PDZGEF Directs Binding to Phosphatidic Acid during Brush Border Formation

PubMed Central

Consonni, Sarah V.; Brouwer, Patricia M.; van Slobbe, Eleonora S.; Bos, Johannes L.

2014-01-01

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. PMID:24858808

Antifouling Thin-Film Composite Membranes by Controlled Architecture of Zwitterionic Polymer Brush Layer.

PubMed

Liu, Caihong; Lee, Jongho; Ma, Jun; Elimelech, Menachem

2017-02-21

In this study, we demonstrate a highly antifouling thin-film composite (TFC) membrane by grafting a zwitterionic polymer brush via atom-transfer radical-polymerization (ATRP), a controlled, environmentally benign chemical process. Initiator molecules for polymerization were immobilized on the membrane surface by bioinspired catechol chemistry, leading to the grafting of a dense zwitterionic polymer brush layer. Surface characterization revealed that the modified membrane exhibits reduced surface roughness, enhanced hydrophilicity, and lower surface charge. Chemical force microscopy demonstrated that the modified membrane displayed foulant-membrane interaction forces that were 1 order of magnitude smaller than those of the pristine TFC membrane. The excellent fouling resistance imparted by the zwitterionic brush layer was further demonstrated by significantly reduced adsorption of proteins and bacteria. In addition, forward osmosis fouling experiments with a feed solution containing a mixture of organic foulants (bovine-serum albumin, alginate, and natural organic matter) indicated that the modified membrane exhibited significantly lower water flux decline compared to the pristine TFC membrane. The controlled architecture of the zwitterionic polymer brush via ATRP has the potential for a facile antifouling modification of a wide range of water treatment membranes without compromising intrinsic transport properties.

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

PubMed

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

Environmental cues and symbiont microbe-associated molecular patterns function in concert to drive the daily remodelling of the crypt-cell brush border of the Euprymna scolopes light organ

PubMed Central

Heath-Heckman, Elizabeth A.C.; Foster, Jamie; Apicella, Michael A.; Goldman, William E.; McFall-Ngai, Margaret

2016-01-01

Summary Recent research has shown that the microbiota affects the biology of associated host epithelial tissues, including their circadian rhythms, although few data are available on how such influences shape the microarchitecture of the brush border. The squid-vibrio system exhibits two modifications of the brush border that supports the symbionts: effacement and repolarization. Together these occur on a daily rhythm in adult animals, at the dawn expulsion of symbionts into the environment, and symbiont colonization of the juvenile host induces an increase in microvillar density. Here we sought to define how these processes are related and the roles of both symbiont colonization and environmental cues. Ultrastructural analyses showed that the juvenile-organ brush borders also efface concomitantly with daily dawn-cued expulsion of symbionts. Manipulation of the environmental light cue and juvenile symbiotic state demonstrated that this behaviour requires the light cue, but not colonization. In contrast, symbionts were required for the observed increase in microvillar density that accompanies post dawn brush-border repolarization; this increase was induced solely by host exposure to phosphorylated lipid A of symbiont cells. These data demonstrate that a partnering of environmental and symbiont cues shapes the brush border and that microbe-associated molecular patterns play a role in the regulation of brush-border microarchitecture. PMID:27062511

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

PubMed

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morduchowicz, G.A.; Sheikh-Hamad, D.; Dwyer, B.E.

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 searchmore » 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.« less

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

PubMed Central

Moghimipour, Eskandar; Tabassi, Sayyed Abolghassem Sajadi; Ramezani, Mohammad; Handali, Somayeh; Löbenberg, Raimar

2016-01-01

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. PMID:27429925

Improving protein resistance of α-Al 2O 3 membranes by modification with POEGMA brushes

NASA Astrophysics Data System (ADS)

He, Huating; Jing, Wenheng; Xing, Weihong; Fan, Yiqun

2011-11-01

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 α-Al2O3 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.

Effect of cisplatin on organic ion transport in membrane vesicles from rat kidney cortex.

PubMed

Williams, P D; Hottendorf, G H

1985-01-01

Purified renal membrane vesicles were utilized to gain indirect information regarding the renal handling of cisplatin. The effects of cisplatin on prototypical organic anion (p-amino-hippurate, PAH) and cation (N1-methylnicotinamide; tetraethylammonium, TEA) transport in brush border and basolateral membrane vesicles prepared from rat kidney cortex were observed. While cisplatin inhibited organic cation transport (N1-methylnicotinamide; TEA) in brush border and basolateral membranes, no interaction with the organic anion (p-amino-hippurate) system was observed. Kinetic analyses revealed that cisplatin is a competitive inhibitor of TEA transport in brush border membranes with a ki of 0.12 mM. While the relationship between organic cation transport inhibition and cisplatin nephrotoxicity is unknown, it may suggest that the cisplatin complex itself is transported into the kidney by the organic cation system. The reported effect of the organic anion, probenecid, on the renal handling of cisplatin is discussed in light of these results.

Brush border enzyme-cleavable linkers: Evaluation for reducing renal uptake of radiolabeled prostate-specific membrane antigen inhibitors.

PubMed

Vaidyanathan, Ganesan; Kang, Choong Mo; McDougald, Darryl; Minn, Il; Brummet, Mary; Pomper, Martin G; Zalutsky, Michael R

2018-05-05

Radiolabeled, low-molecular-weight prostate-specific membrane antigen (PSMA) inhibitors based on the Glu-ureido pharmacophore show promise for the detection and treatment of castration-resistant prostate cancer; however, high renal retention of activity, related in part to overexpression of PSMA in kidneys can be problematic. The goal of the current study was to investigate the use of brush border enzyme-cleavable linkers as a strategy for reducing kidney activity levels from radiolabeled PSMA inhibitors. PSMA-769 (6), a derivative of the prototypical PSMA inhibitor (((S)‑1‑carboxy‑5‑(4‑iodobenzamido)pentyl)carbamoyl)glutamate (12) modified to contain a Gly-Tyr linker, and its protected tin precursor (11) were synthesized starting from the basic pharmacophore molecule Lys-urea-Glu. An analogue of 6 containing d‑tyrosine in lieu of l‑tyrosine (PSMA-769-d-tyrosine) and the corresponding tin precursor (d-11) also were synthesized. Both radioiodinated and 211 At-labeled 6 were synthesized by radiohalogenation of 11 and deprotection in situ. Similarly, radioiodinated d-6 was synthesized from d-11. Paired label biodistribution of [ 125 I]12 and [ 131 I]6 was performed in normal mice and in SCID mice bearing both PC3 PIP (PSMA+) and PC3 flu (PSMA-) subcutaneous prostate carcinoma xenografts. The biodistribution of [ 131 I]6 and [ 211 At]6 was also evaluated in this tumor model. Biodistribution of the two radioiodinated diastereomers of 6 was evaluated in normal mice and urine samples were analyzed for the presence of 4‑iodohippuric acid. Compounds [ 131 I]6 and [ 211 At]6 were synthesized from 11 in overall radiochemical yields of 32.5 ± 0.1% (n = 4) and 22% (n = 1), respectively; radiochemical purity was >95%. In normal mice, renal uptake of [ 131 I]6 was 1.4-, 2.8- and 161-fold lower than that seen for co-injected [ 125 I]12 at 1 h, 4 h and 21 h, respectively. In tumor-bearing mice, kidney uptake of [ 131 I]6 was similar to that for

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

PubMed

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.

Effect of dietary fatty acids on jejunal and ileal oleic acid uptake by rat brush border membrane vesicles.

PubMed

Prieto, R M; Stremmel, W; Sales, C; Tur, J A

1996-04-18

To test the effect of dietary fatty acids on fatty acid uptake, the influx kinetics of a representative long-chain fatty acid, 3H-oleic acid, in both the jejunum and ileum of rats has been studied using brush border membrane vesicles (BBMV). Animals were fed with semipurified diets containing 5 g fat/100 g diet, as corn oil (control group), safflower oil (unsaturated group) and coconut oil hydrogenated (saturated group). With increasing unbound oleate concentration in the medium, the three dietary groups showed saturable kinetics in both jejunal and ileal BBMV (controls: Vmax = 0.15 +/- 0.01 nmol x mg protein-1 x 5 min-1 and Km = 136 +/- 29.1 nmol for jejunum, and Vmax = 0.23 +/- 0.03 nmol x mg protein-1 x 5 min-1 and Km = 196 +/- 50.3 nmol for ileum; unsaturated: Vmax = 0.28 +/- 0.05 nmol x mg protein-1 x 5 min-1 and Km = 242.7 +/- 91.8 nmol for jejunum, and Vmax = 1.29 +/- 0.06 nmol x mg protein-1 x 5 min-1 and Km = 509.8 +/- 97.5 nmol for ileum; saturated: Vmax = 0.03 +/- 0.01 nmol x mg protein-1 x 5 min-1 and Km = 124.5 +/- 72.6 nmol for jejunum, and Vmax = 0.04 +/- 0.01 nmol x mg protein -1.5 min-1 and Km = 205.6 +/- 85.3 nmol for ileum). These results support the theory that feeding an isocaloric diet containing only unsaturated fatty acids enhanced oleic acid uptake, and feeding an isocaloric diet containing only saturated fatty acids decreased oleic acid uptake. The results obtained in the present work also show the adaptative ability of jejunum and ileum to the type of dietary fat.

Differential interaction of Escherichia coli heat-labile toxin and cholera toxin with pig intestinal brush border glycoproteins depending on their ABH and related blood group antigenic determinants.

PubMed

Balanzino, L E; Barra, J L; Monferran, C G; Cumar, F A

1994-04-01

The ability of glycoproteins from pig intestinal brush border membranes (BBM) to bind cholera toxin (CT) or heat-labile toxins from strains of Escherichia coli isolated from human (LTh) or pig (LTp) intestines was studied. Glycoproteins capable of binding the toxins are also recognized by antibodies or lectins specific for ABO(H) blood group and related antigens. Pigs expressing A, H, or I antigenic determinants were used for comparison. The toxin-binding capacity of a glycoprotein depends on the toxin type and the blood group epitope borne by the glycoprotein. LTh and LTp preferably bound to several blood group A-active glycoproteins rather than H-active glycoproteins. By contrast, CT practically did not recognize either blood group A- or blood group H-active glycoproteins, while glycoproteins from pigs expressing I antigenic determinants were able to interact with LTh, LTp, and CT. LTh, LTp, or CT glycoprotein binding was selectively inhibited by specific lectins or monosaccharides. Affinity purification of the toxin binding brush border glycoproteins on the basis of their blood group reactivity suggests that such glycoproteins are hydrolytic enzymes. BBM from A+ pigs contain about 27 times more LTh binding sites, in addition to those recognized by CT, than an equivalent membrane preparation from H+ pigs. The present findings may help clarify some previous unclear results on LTh binding to intestinal BBM glycoproteins obtained by use of animals not typed by their ABO(H) blood group phenotype.

Smart polymer brush nanostructures guide the self-assembly of pore-spanning lipid bilayers with integrated membrane proteins

NASA Astrophysics Data System (ADS)

Wilhelmina de Groot, G.; Demarche, Sophie; Santonicola, M. Gabriella; Tiefenauer, Louis; Vancso, G. Julius

2014-01-01

Nanopores in arrays on silicon chips are functionalized with pH-responsive poly(methacrylic acid) (PMAA) brushes and used as supports for pore-spanning lipid bilayers with integrated membrane proteins. Robust platforms are created by the covalent grafting of polymer brushes using surface-initiated atom transfer radical polymerization (ATRP), resulting in sensor chips that can be successfully reused over several assays. His-tagged proteins are selectively and reversibly bound to the nitrilotriacetic acid (NTA) functionalization of the PMAA brush, and consequently lipid bilayer membranes are formed. The enhanced membrane resistance as determined by electrochemical impedance spectroscopy and free diffusion of dyed lipids observed as fluorescence recovery after photobleaching confirmed the presence of lipid bilayers. Immobilization of the His-tagged membrane proteins on the NTA-modified PMAA brush near the pore edges is characterized by fluorescence microscopy. This system allows us to adjust the protein density in free-standing bilayers, which are stabilized by the polymer brush underneath. The potential application of the integrated platform for ion channel protein assays is demonstrated.

Effect of cephalosporins on organic ion transport in renal membrane vesicles from rat and rabbit kidney cortex.

PubMed

Williams, P D; Hitchcock, M J; Hottendorf, G H

1985-03-01

The effects of cephaloridine and cephalothin on prototypical organic anion (p-aminohippurate, PAH) and cation (N-methylnicotinamide, NMN) transport were observed in brush border and basolateral membrane vesicles prepared from rat and rabbit renal cortex. The cephalosporins interacted with both the cationic and anionic transport systems. Cephalothin inhibited PAH transport in basolateral and brush border membrane in both rats and rabbits. Cephaloridine on the other hand inhibited PAH and NMN transport across rabbit basolateral membranes while it showed a lack of interaction with transport systems in rat basolateral membranes. Conversely, cephaloridine inhibited brush border transport of PAH and NMN in the rat but not in the rabbit. These results provide indirect evidence that cephalothin may be secreted across the renal tubule cell in rats and rabbits while cephaloridine may not accumulate in the rat kidney and becomes trapped in rabbit renal tubule cells. The differences in transport effects observed may explain intra- and interspecies differences in susceptibility to cephalosporin nephrotoxicity.

Activation of intestinal brush border guanylate cyclase by aromatic disulphide compounds.

PubMed Central

elDeib, M M; Parker, C D; White, A A

1991-01-01

Guanylate cyclase in pig intestinal brush border membranes was stimulated by certain aromatic disulphides. The most effective were 6-thioguanine disulphide [(TGS)2], 6-mercaptopurine disulphide, 6,6'-dithiodinicotinic acid, 5,5'-dithiobis-(2-nitrobenzoic acid) and 5-carboxy-2-thiouracil disulphide. (TGS)2 stimulated activity 15-fold when present at 0.1 mM. The optimum concentration for each disulphide was different, and higher concentrations were inhibitory. There was no activation by alkyl disulphides or by N-ethylmaleimide. Activation by 50 microM-(TGS)2 was partially reversed by later addition of 0.1 mM-dithiothreitol, whereas activation by the Escherichia coli heat-stable enterotoxin STa was relatively unaffected. Pretreatment of the membranes with (TGS)2 produced a concentration-dependent inhibition of STa-stimulated activity, while stimulating basal activity, until the activities were equal at 50 microM. Activity was [Mg2+]-dependent, the optimal [Mg2+] progressively increasing as the enzyme was stimulated by (TGS)2, STa and Lubrol PX respectively. However, (TGS)2 pretreatment prevented the shift to higher [Mg2+]optima induced by STa or Lubrol alone. Substitution of Mn2+ for Mg2+ in the reaction elevated basal activity and eliminated by activation (TGS)2. (TGS)2 only inhibited Mn2(+)-dependent activity (both basal and stimulated). The affinity of 125I-STa for its receptor was slightly increased by (TGS)2. We propose that (TGS)2 undergoes thiol-disulphide exchange with at least three different protein thiols of decreasing reactivity. The first is associated with Mg2(+)-dependent activation, the second is associated with a tonic inhibition of activity and the third is associated with the catalytic activity, although probably not at the active site. PMID:1673335

Freeze-thaw and high-voltage discharge allow macromolecule uptake into ileal brush-border vesicles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Donowitz, M.; Emmer, E.; McCullen, J.

1987-06-01

High-voltage discharge or one cycle of freeze-thawing are shown to transiently permeabilize rabbit ileal brush-border membrane vesicles to macromolecules. Uptake of the radiolabeled macromolecule dextran, mol wt 70,000, used as a marker for vesicle permeability, was determined by a rapid filtration technique, with uptake defined as substrate associated with the vesicle and releasable after incubation of vesicles with 0.1% saponin. Dextran added immediately after electric shock (2000 V) or at the beginning of one cycle of freeze-thawing was taken up approximately eightfold compared with control. ATP also was taken up into freeze-thawed vesicles, whereas there was no significant uptake intomore » control vesicles. The increase in vesicle permeability was reversible, based on Na-dependent D-glucose uptake being decreased when studied 5 but not 15 min after electric shock, and was not significantly decreased after completion of one cycle of freeze-thawing. In addition, adenosine 3',5'-cyclic monophosphate and Ca/sup 2 +/-calmodulin-dependent protein kinase activity were similar in control vesicles and vesicles exposed to high-voltage discharge or freeze-thawing. Also, vesicles freeze-thawed with (/sup 32/P)ATP demonstrated increased phosphorylation compared with nonfrozen vesicles, while freeze-thawing did not alter vesicle protein as judged by Coomassie blue staining. These techniques should allow intestinal membrane vesicles to be used for studies of intracellular control of transport processes, for instance, studies of protein kinase regulation of transport.« less

Vigabatrin transport across the human intestinal epithelial (Caco-2) brush-border membrane is via the H+-coupled amino-acid transporter hPAT1

PubMed Central

Abbot, Emily L; Grenade, Danielle S; Kennedy, David J; Gatfield, Kelly M; Thwaites, David T

2005-01-01

The aim of this investigation was to determine if the human proton-coupled amino-acid transporter 1 (hPAT1 or SLC36A1) is responsible for the intestinal uptake of the orally-administered antiepileptic agent 4-amino-5-hexanoic acid (vigabatrin). The Caco-2 cell line was used as a model of the human small intestinal epithelium. Competition experiments demonstrate that [3H]GABA uptake across the apical membrane was inhibited by vigabatrin and the GABA analogues trans-4-aminocrotonic acid (TACA) and guvacine, whereas 1-(aminomethyl)cyclohexaneacetic acid (gabapentin) had no affect. Experiments with 2′,7′-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF)-loaded Caco-2 cells demonstrate that apical exposure to vigabatrin and TACA induce comparable levels of intracellular acidification (due to H+/amino-acid symport) to that generated by GABA, suggesting that they are substrates for a H+-coupled absorptive transporter such as hPAT1. In hPAT1 and mPAT1-expressing Xenopus laevis oocytes [3H]GABA uptake was inhibited by vigabatrin, TACA and guvacine, whereas gabapentin failed to inhibit [3H]GABA uptake. In Na+-free conditions, vigabatrin and TACA evoked similar current responses (due to H+/amino-acid symport) in hPAT1-expressing oocytes under voltage-clamp conditions to that induced by GABA (whereas no current was observed in water-injected oocytes) consistent with the ability of these GABA analogues to inhibit [3H]GABA uptake. This study demonstrates that hPAT1 is the carrier responsible for the uptake of vigabatrin across the brush-border membrane of the small intestine and emphasises the therapeutic potential of hPAT1 as a delivery route for orally administered, clinically significant GABA-related compounds. PMID:16331283

Trafficking Ion Transporters to the Apical Membrane of Polarized Intestinal Enterocytes.

PubMed

Engevik, Amy Christine; Goldenring, James R

2018-01-02

Epithelial cells lining the gastrointestinal tract require distinct apical and basolateral domains to function properly. Trafficking and insertion of enzymes and transporters into the apical brush border of intestinal epithelial cells is essential for effective digestion and absorption of nutrients. Specific critical ion transporters are delivered to the apical brush border to facilitate fluid and electrolyte uptake. Maintenance of these apical transporters requires both targeted delivery and regulated membrane recycling. Examination of altered apical trafficking in patients with Microvillus Inclusion disease caused by inactivating mutations in MYO5B has led to insights into the regulation of apical trafficking by elements of the apical recycling system. Modeling of MYO5B loss in cell culture and animal models has led to recognition of Rab11a and Rab8a as critical regulators of apical brush border function. All of these studies show the importance of apical membrane trafficking dynamics in maintenance of polarized epithelial cell function. Copyright © 2018 Cold Spring Harbor Laboratory Press; all rights reserved.

Functional Regulation of Sugar Assimilation by N-Glycan-specific Interaction of Pancreatic α-Amylase with Glycoproteins of Duodenal Brush Border Membrane*

PubMed Central

Asanuma-Date, Kimie; Hirano, Yuki; Le, Na; Sano, Kotone; Kawasaki, Nana; Hashii, Noritaka; Hiruta, Yoko; Nakayama, Ken-ichi; Umemura, Mariko; Ishikawa, Kazuhiko; Sakagami, Hiromi; Ogawa, Haruko

2012-01-01

Porcine pancreatic α-amylase (PPA) binds to N-linked glycans of glycoproteins (Matsushita, H., Takenaka, M., and Ogawa, H. (2002) J. Biol Chem., 277, 4680–4686). Immunostaining revealed that PPA is located at the brush-border membrane (BBM) of enterocytes in the duodenum and that the binding is inhibited by mannan but not galactan, indicating that PPA binds carbohydrate-specifically to BBM. The ligands for PPA in BBM were identified as glycoprotein N-glycans that are significantly involved in the assimilation of glucose, including sucrase-isomaltase (SI) and Na+/Glc cotransporter 1 (SGLT1). Binding of SI and SGLT1 in BBM to PPA was dose-dependent and inhibited by mannan. Using BBM vesicles, we found functional changes in PPA and its ligands in BBM due to the N-glycan-specific interaction. The starch-degrading activity of PPA and maltose-degrading activity of SI were enhanced to 240 and 175%, respectively, while Glc uptake by SGLT1 was markedly inhibited by PPA at high but physiologically possible concentrations, and the binding was attenuated by the addition of mannose-specific lectins, especially from Galanthus nivalis. Additionally, recombinant human pancreatic α-amylases expressed in yeast and purified by single-step affinity chromatography exhibited the same carbohydrate binding specificity as PPA in binding assays with sugar-biotinyl polymer probes. The results indicate that mammalian pancreatic α-amylases share a common carbohydrate binding activity and specifically bind to the intestinal BBM. Interaction with N-glycans in the BBM activated PPA and SI to produce much Glc on the one hand and to inhibit Glc absorption by enterocytes via SGLT1 in order to prevent a rapid increase in blood sugar on the other. PMID:22584580

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

PubMed

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.

Electroneutral, HCO3(-)-independent, pH gradient-dependent uphill transport of Cl- by ileal brush-border membrane vesicles. Possible role in the pathogenesis of chloridorrhea.

PubMed Central

Vasseur, M; Caüzac, M; Alvarado, F

1989-01-01

By applying a rapid filtration technique to isolated brush border membrane vesicles from guinea pig ileum, 36Cl uptake was quantified in the presence and absence of electrical, pH and alkali-metal ion gradients. A mixture of 20 mM-Hepes and 40 mM-citric acid, adjusted to the desired pH with Tris base, was found to be the most suitable buffer. Malate and Mes could be used to replace the citrate, but succinate, acetate and maleate proved to be unsuitable. In the absence of a pH gradient (pHout:pHin = 7.5:7.5), Cl- uptake increased slightly when an inside-positive membrane potential was applied, but uphill transport was never observed. A pH gradient (pHout:pHin = 5.0:7.5) induced both a 400% increase in the initial Cl- influx rate and a long-lasting (20 to 300 s) overshoot, indicating that a proton gradient can furnish the driving force for uphill Cl- transport. Under pH gradient conditions, initial Cl- entry rates had the following characteristics. (1) They were unaffected by cis-Na+ and/or -K+, indicating the absence of Cl-/K+, Cl-/Na+ or Cl-/K+/Na+ symport activity. (2) Inhibition by 20-100 mM-trans-Na+ and/or -K+ occurred, independent of the existence of an ion gradient. (3) Cl- entry was practically unaffected by short-circuiting the membrane potential with equilibrated potassium and valinomycin. (4) Carbonyl cyanide m-chlorophenylhydrazone was strongly inhibitory and so, to a lesser extent, was 4-acetamido-4'-isothiocyanostilbene-2,2'-disulphonic acid [(SITS)], independent of the sign and size of the membrane potential. (5) Cl- entry was negligibly increased (less than 30%) by either trans-Cl- or -HCO3-, indicating the absence of an obligatory Cl-/anion antiport activity. In contrast, the height of the overshoot at 60 s was increased by trans-Cl-, indicating time-dependent inhibition of 36Cl efflux. That competitive inhibition of 36Cl fluxes by anions is involved here is supported by initial influx rate experiments demonstrating: (1) the saturability of Cl

Expression of Mucin-Type Glycoprotein K88 Receptors Strongly Correlates with Piglet Susceptibility to K88+ Enterotoxigenic Escherichia coli, but Adhesion of This Bacterium to Brush Borders Does Not

PubMed Central

Francis, David H.; Grange, Philippe A.; Zeman, David H.; Baker, Diane R.; Sun, Ronggai; Erickson, Alan K.

1998-01-01

Three antigenic variants of the K88 fimbrial adhesin exist in nature, K88ab, K88ac, and K88ad. Enterotoxigenic Escherichia coli (ETEC) strains that produce these fimbriae cause life-threatening diarrhea in some but not all young pigs. The susceptibility of pigs to these organisms has been correlated with the adherence of bacteria to isolated enterocyte brush borders. Whether that correlation holds for multiple K88 variants and over a broad genetic base of pigs is unknown and was the impetus for this study. We also desired to examine the correlation of the expression of a porcine intestinal brush border mucin-type glycoprotein (IMTGP) which binds K88ab and K88ac with the susceptibility of piglets to K88+ ETEC. Of 31 neonatal gnotobiotic pigs inoculated with K88ab+ or K88ac+ ETEC, 13 developed severe diarrhea, became dehydrated, and died or became moribund. Another pig became severely lethargic but not dehydrated. In vitro brush border adherence analysis was not possible for 10 of the severely ill pigs due to colonization by challenge strains. However, of the 17 pigs that did not become severely ill, 8 (47%) had brush borders that supported the adherence of K88ab+ and K88ac+ bacteria in vitro, suggesting a poor correlation between in vitro brush border adherence and piglet susceptibility to K88+ ETEC. By contrast, the expression of IMTGP was highly correlated with susceptibility to K88+ ETEC. Of the 12 pigs that produced IMTGP, 11 developed severe diarrhea. The other pig that produced IMTGP became lethargic but not severely diarrheic. Only 2 of 18 pigs that did not produce IMTGP became severely diarrheic. Colonizing bacteria were observed in histologic sections of intestines from all pigs that expressed IMTGP except for the one that did not develop severe diarrhea. However, colonizing bacteria were observed in histologic sections from only one pig that did not produce IMTGP. The bacterial concentration in the jejuna and ilea of pigs expressing IMTGP was significantly

Structural specificity of mucosal-cell transport and metabolism of peptide drugs: implication for oral peptide drug delivery

NASA Technical Reports Server (NTRS)

Bai, J. P.; Amidon, G. L.

1992-01-01

The brush border membrane of intestinal mucosal cells contains a peptide carrier system with rather broad substrate specificity and various endo- and exopeptidase activities. Small peptide (di-/tripeptide)-type drugs with or without an N-terminal alpha-amino group, including beta-lactam antibiotics and angiotensin-converting enzyme (ACE) inhibitors, are transported by the peptide transporter. Polypeptide drugs are hydrolyzed by brush border membrane proteolytic enzymes to di-/tripeptides and amino acids. Therefore, while the intestinal brush border membrane has a carrier system facilitating the absorption of di-/tripeptide drugs, it is a major barrier limiting oral availability of polypeptide drugs. In this paper, the specificity of peptide transport and metabolism in the intestinal brush border membrane is reviewed.

Effect of chronic hypo and hypervitaminosis C on the brush border enzymes and the intestinal uptake of glucose and alanine.

PubMed

Mahmood, A; Chauhan, V P; Lyall, V; Sarkar, A K

1979-08-15

Brush border sucrase and alkaline phosphatase activities are considerably enhanced in the intestine of ascorbic acid deficient guinea-pigs. Similar increase in the uptake of D-glucose and L-alanine also occurs in chronic vitamin C deficiency. However the permeability of D-glucose and L-alanine in the intestine of animals fed with large doses of vitamin C is severely depressed, with a reduction in the levels of sucrase and alkaline phosphatase activities.

Trans-Membrane Area Asymmetry Controls the Shape of Cellular Organelles

PubMed Central

Beznoussenko, Galina V.; Pilyugin, Sergei S.; Geerts, Willie J. C.; Kozlov, Michael M.; Burger, Koert N. J.; Luini, Alberto; Derganc, Jure; Mironov, Alexander A.

2015-01-01

Membrane organelles often have complicated shapes and differ in their volume, surface area and membrane curvature. The ratio between the surface area of the cytosolic and luminal leaflets (trans-membrane area asymmetry (TAA)) determines the membrane curvature within different sites of the organelle. Thus, the shape of the organelle could be critically dependent on TAA. Here, using mathematical modeling and stereological measurements of TAA during fast transformation of organelle shapes, we present evidence that suggests that when organelle volume and surface area are constant, TAA can regulate transformation of the shape of the Golgi apparatus, endosomal multivesicular bodies, and microvilli of brush borders of kidney epithelial cells. Extraction of membrane curvature by small spheres, such as COPI-dependent vesicles within the Golgi (extraction of positive curvature), or by intraluminal vesicles within endosomes (extraction of negative curvature) controls the shape of these organelles. For instance, Golgi tubulation is critically dependent on the fusion of COPI vesicles with Golgi cisternae, and vice versa, for the extraction of membrane curvature into 50–60 nm vesicles, to induce transformation of Golgi tubules into cisternae. Also, formation of intraluminal ultra-small vesicles after fusion of endosomes allows equilibration of their TAA, volume and surface area. Finally, when microvilli of the brush border are broken into vesicles and microvilli fragments, TAA of these membranes remains the same as TAA of the microvilli. Thus, TAA has a significant role in transformation of organelle shape when other factors remain constant. PMID:25761238

Dimerization and actin-bundling properties of villin and its role in the assembly of epithelial cell brush borders.

PubMed

George, Sudeep P; Wang, Yaohong; Mathew, Sijo; Srinivasan, Kamalakkannan; Khurana, Seema

2007-09-07

Villin is a major actin-bundling protein in the brush border of epithelial cells. In this study we demonstrate for the first time that villin can bundle actin filaments using a single F-actin binding site, because it has the ability to self-associate. Using fluorescence resonance energy transfer, we demonstrate villin self-association in living cells in microvilli and in growth factor-stimulated cells in membrane ruffles and lamellipodia. Using sucrose density gradient, size-exclusion chromatography, and matrix-assisted laser desorption ionization time-of-flight, the majority of villin was identified as a monomer or dimer. Villin dimers were also identified in Caco-2 cells, which endogenously express villin and Madin-Darby canine kidney cells that ectopically express villin. Using truncation mutants of villin, site-directed mutagenesis, and fluorescence resonance energy transfer, an amino-terminal dimerization site was identified that regulated villin self-association in parallel conformation as well as actin bundling by villin. This detailed analysis describes for the first time microvillus assembly by villin, redefines the actin-bundling function of villin, and provides a molecular mechanism for actin bundling by villin, which could have wider implications for other actin cross-linking proteins that share a villin-like headpiece domain. Our study also provides a molecular basis to separate the morphologically distinct actin-severing and actin-bundling properties of villin.

Ultrathin graphene oxide-based hollow fiber membranes with brush-like CO2-philic agent for highly efficient CO2 capture.

PubMed

Zhou, Fanglei; Tien, Huynh Ngoc; Xu, Weiwei L; Chen, Jung-Tsai; Liu, Qiuli; Hicks, Ethan; Fathizadeh, Mahdi; Li, Shiguang; Yu, Miao

2017-12-13

Among the current CO 2 capture technologies, membrane gas separation has many inherent advantages over other conventional techniques. However, fabricating gas separation membranes with both high CO 2 permeance and high CO 2 /N 2 selectivity, especially under wet conditions, is a challenge. In this study, sub-20-nm thick, layered graphene oxide (GO)-based hollow fiber membranes with grafted, brush-like CO 2 -philic agent alternating between GO layers are prepared by a facile coating process for highly efficient CO 2 /N 2 separation under wet conditions. Piperazine, as an effective CO 2 -philic agent, is introduced as a carrier-brush into the GO nanochannels with chemical bonding. The membrane exhibits excellent separation performance under simulated flue gas conditions with CO 2 permeance of 1,020 GPU and CO 2 /N 2 selectivity as high as 680, demonstrating its potential for CO 2 capture from flue gas. We expect this GO-based membrane structure combined with the facile coating process to facilitate the development of ultrathin GO-based membranes for CO 2 capture.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malczynski, Leonard A.; Passell, Howard David; Forster, Craig B.

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 methodsmore » 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.« less

Polymer Brushes as Functional, Patterned Surfaces for Nanobiotechnology.

PubMed

Welch, M Elizabeth; Xu, Youyong; Chen, Hongjun; Smith, Norah; Tague, Michele E; Abruña, Héctor D; Baird, Barbara; Ober, Christopher K

2013-01-01

Polymer brushes have many desirable characteristics such as the ability to tether molecules to a substrate or change the properties of a surface. Patterning of polymer films has been an area of great interest due to the broad range of applications including bio-related and medicinal research. Consequently, we have investigated patterning techniques for polymer brushes which allow for two different functionalities on the same surface. This method has been applied to a biosensor device which requires both polymer brushes and a photosensitizer to be polymerized on a patterned gold substrate. Additionally, the nature of patterned polymer brushes as removable thin films was explored. An etching process has enabled us to lift off very thin membranes for further characterization with the potential of using them as Janus membranes for biological applications.

Short-term fasting induces intra-hepatic lipid accumulation and decreases intestinal mass without reduced brush-border enzyme activity in mink (Mustela vison) small intestine.

PubMed

Bjornvad, C R; Elnif, J; Sangild, P T

2004-11-01

For many mammalian species short-term fasting is associated with intestinal atrophy and decreased digestive capacity. Under natural conditions, strictly carnivorous animals often experience prey scarcity during winter, and they may therefore be particularly well adapted to short-term food deprivation. To examine how the carnivorous gastrointestinal tract is affected by fasting, small-intestinal structure, brush-border enzyme activities and hepatic structure and function were examined in fed mink (controls) and mink that had been fasted for 1-10 days. During the first 1-2 days of fasting, intestinal mass decreased more rapidly than total body mass and villus heights were reduced 25-40%. In contrast, tissue-specific activity of the brush-border enzymes sucrase, maltase, lactase, aminopeptidase A and dipeptidylpeptidase IV increased 0.5- to 1.5-fold at this time, but returned to prefasting levels after 6 days of fasting. After 6-10 days of fasting there was a marked increase in the activity of hepatic enzymes and accumulation of intra-hepatic lipid vacuoles. Thus, mink may be a useful model for studying fasting-induced intestinal atrophy and adaptation as well as mechanisms involved in accumulation of intra-hepatic lipids following food deprivation in strictly carnivorous domestic mammals, such as cats and ferrets.

The effect of essential fatty acid deficiency on the stimulation of intestinal calcium transport by 1,25-dihydroxyvitamin D3.

PubMed

Kreutter, D; Matsumoto, T; Peckham, R; Zawalich, K; Wen, W H; Zolock, D T; Rasmussen, H

1983-04-25

The effect of altering the lipid composition of the brush-border membrane on the ability of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) to stimulate calcium transport across the intestinal mucosa was examined by raising chicks on a vitamin D, essential fatty acid-deficient diet (-DEFAD) and measuring calcium absorption from duodenal sacs in situ and calcium uptake into brush-border membrane vesicles in vitro. Administration of 1,25-(OH)2D3 to -DEFAD and to -D control chicks led to the same increase in calcium transport in situ, whereas calcium transport in isolated brush-border membrane vesicles was not stimulated in the EFAD group, but responded normally in the control group. When the incubation temperature was increased to 34 degrees C, brush-border membrane vesicles from 1,25-(OH)2D3-treated essential fatty acid-deficient (+DE-FAD) chicks accumulated calcium at a faster rate than did vesicles from -DEFAD chicks. There was a marked decrease in the linoleic acid content and an increase in the oleic acid content of both the total lipid extract of the brush-border membrane as well as the phosphatidylcholine and phosphatidylethanolamine fractions, which could explain the temperature sensitivity of the in vitro system. When the diet of the EFAD chicks was supplemented with linoleic acid, the rate of calcium uptake into subsequently isolated vesicles from +DE-FAD chicks correlated with the amount of linoleic acid in the brush-border membranes. These results support the concept that the action of 1,25-(OH)2D3 on membrane lipid turnover and structure plays a critically important role in the 1,25-(OH)2D3-mediated cellular transport responses.

Does apical membrane GLUT2 have a role in intestinal glucose uptake?

PubMed

Naftalin, Richard J

2014-01-01

It has been proposed that the non-saturable component of intestinal glucose absorption, apparent following prolonged exposure to high intraluminal glucose concentrations, is mediated via the low affinity glucose and fructose transporter, GLUT2, upregulated within the small intestinal apical border. The evidence that the non-saturable transport component is mediated via an apical membrane sugar transporter is that it is inhibited by phloretin, after exposure to phloridzin. Since the other apical membrane sugar transporter, GLUT5, is insensitive to inhibition by either cytochalasin B, or phloretin, GLUT2 was deduced to be the low affinity sugar transport route. As in its uninhibited state, polarized intestinal glucose absorption depends both on coupled entry of glucose and sodium across the brush border membrane and on the enterocyte cytosolic glucose concentration exceeding that in both luminal and submucosal interstitial fluids, upregulation of GLUT2 within the intestinal brush border will usually stimulate downhill glucose reflux to the intestinal lumen from the enterocytes; thereby reducing, rather than enhancing net glucose absorption across the luminal surface. These states are simulated with a computer model generating solutions to the differential equations for glucose, Na and water flows between luminal, cell, interstitial and capillary compartments. The model demonstrates that uphill glucose transport via SGLT1 into enterocytes, when short-circuited by any passive glucose carrier in the apical membrane, such as GLUT2, will reduce transcellular glucose absorption and thereby lead to increased paracellular flow. The model also illustrates that apical GLUT2 may usefully act as an osmoregulator to prevent excessive enterocyte volume change with altered luminal glucose concentrations.

Does apical membrane GLUT2 have a role in intestinal glucose uptake?

PubMed Central

Naftalin, Richard J

2014-01-01

It has been proposed that the non-saturable component of intestinal glucose absorption, apparent following prolonged exposure to high intraluminal glucose concentrations, is mediated via the low affinity glucose and fructose transporter, GLUT2, upregulated within the small intestinal apical border. The evidence that the non-saturable transport component is mediated via an apical membrane sugar transporter is that it is inhibited by phloretin, after exposure to phloridzin. Since the other apical membrane sugar transporter, GLUT5, is insensitive to inhibition by either cytochalasin B, or phloretin, GLUT2 was deduced to be the low affinity sugar transport route. As in its uninhibited state, polarized intestinal glucose absorption depends both on coupled entry of glucose and sodium across the brush border membrane and on the enterocyte cytosolic glucose concentration exceeding that in both luminal and submucosal interstitial fluids, upregulation of GLUT2 within the intestinal brush border will usually stimulate downhill glucose reflux to the intestinal lumen from the enterocytes; thereby reducing, rather than enhancing net glucose absorption across the luminal surface. These states are simulated with a computer model generating solutions to the differential equations for glucose, Na and water flows between luminal, cell, interstitial and capillary compartments. The model demonstrates that uphill glucose transport via SGLT1 into enterocytes, when short-circuited by any passive glucose carrier in the apical membrane, such as GLUT2, will reduce transcellular glucose absorption and thereby lead to increased paracellular flow. The model also illustrates that apical GLUT2 may usefully act as an osmoregulator to prevent excessive enterocyte volume change with altered luminal glucose concentrations. PMID:25671087

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

PubMed

Danielsen, E Michael; Hansen, Gert H

2017-07-03

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 passage can be achieved by cell membrane permeabilization and/or by endocytic uptake and subsequent transcytosis. One broad class of PEs is surfactants which act by inserting into the cell membrane, thereby perturbing its integrity, but little is known about how the dynamics of the membrane are affected. In the present work, the interaction of the surfactants lauroyl-L-carnitine, 1-decanoyl-rac-glycerol, and nonaethylene glycol monododecyl ether with the intestinal epithelium was studied in organ cultured pig jejunal mucosal explants. As expected, at 2 mM, these agents rapidly permeabilized the enterocytes 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 microvilli. Such a membrane fusogenic activity could also explain the observed formation of vesicle-like structures and large vacuoles along the lateral cell membranes of the enterocytes induced by the PEs. We conclude that the surfactant action of the PEs selected in this study not only permeabilized the enterocytes, but profoundly changed the dynamic properties of their constituent cell membranes.

Anti-Fouling Double-Skinned Forward Osmosis Membrane with Zwitterionic Brush for Oily Wastewater Treatment.

PubMed

Ong, Chi Siang; Al-Anzi, Bader; Lau, Woei Jye; Goh, Pei Sean; Lai, Gwo Sung; Ismail, Ahmad Fauzi; Ong, Yue Seong

2017-07-31

Despite its attractive features for energy saving separation, the performance of forward osmosis (FO) has been restricted by internal concentration polarization and fast fouling propensity that occur in the membrane sublayer. These problems have significantly affected the membrane performance when treating highly contaminated oily wastewater. In this study, a novel double-skinned FO membrane with excellent anti-fouling properties has been developed for emulsified oil-water treatment. The double-skinned FO membrane comprises a fully porous sublayer sandwiched between a highly dense polyamide (PA) layer for salt rejection and a fairly loose dense bottom zwitterionic layer for emulsified oil particle removal. The top dense PA layer was synthesized via interfacial polymerization meanwhile the bottom layer was made up of a zwitterionic polyelectrolyte brush - (poly(3-(N-2-methacryloxyethyl-N,N-dimethyl) ammonatopropanesultone), abbreviated as PMAPS layer. The resultant double-skinned membrane exhibited a high water flux of 13.7 ± 0.3 L/m 2 .h and reverse salt transport of 1.6 ± 0.2 g/m 2 .h under FO mode using 2 M NaCl as the draw solution and emulsified oily solution as the feed. The double-skinned membrane outperforms the single-skinned membrane with much lower fouling propensity for emulsified oil-water separation.

Na+-independent D-glucose transport in rabbit renal basolateral membranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheung, P.T.; Hammerman, M.R.

1988-05-01

To define the mechanism by which glucose is transported across the basolateral membrane of the renal proximal tubular cell, we measured D-(14C)glucose uptake in basolateral membrane vesicles from rabbit kidney. Na+-dependent D-glucose transport, demonstrable in brush-border vesicles, could not be demonstrated in basolateral membrane vesicles. In the absence of Na+, the uptake of D-(14C)glucose in basolateral vesicles was more rapid than that of L-(3H)glucose over a concentration range of 1-50 mM. Subtraction of the latter from the former uptakes revealed a saturable process with apparent Km of 9.9 mM and Vmax of 0.80 nmol.mg protein-1.s-1. To characterize the transport componentmore » of D-glucose uptake in basolateral vesicles, we measured trans stimulation of 2 mM D-(14C)glucose entry in the absence of Na+. Trans stimulation could be effected by preloading basolateral vesicles with D-glucose, 2-deoxy-D-glucose, or 3-O-methyl-D-glucose, but not with L-glucose or alpha-methyl-D-glucoside. Trans-stimulated D-(14C)glucose uptake was inhibited by 0.1 mM phloretin or cytochalasin B but not phlorizin. In contrast, Na+-dependent D-(14C)glucose transport in brush-border vesicles was inhibited by phlorizin but not phloretin or cytochalasin B. Our findings are consistent with the presence of a Na+-independent D-glucose transporter in the proximal tubular basolateral membrane with characteristics similar to those of transporters present in nonepithelial cells.« less

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

PubMed

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.

Self-Renewing Microns-Thick Biopolymer Brush Made of Hyaluronan under Active Synthesis

NASA Astrophysics Data System (ADS)

Wei, W.; Washburn, J.; Weigel, P.; Curtis, J. E.

Hyaluronan (HA) is a large anionic polysaccharide distributed throughout many vertebrate tissues. We introduce a technology to produce dynamic HA polymer brush interfaces. The strategy relies on the enzyme hyaluronan synthase (HA synthase), which synthesizes and extrudes HA polymers up to 20 microns in length. We show that interfaces decorated by HA synthase-rich membrane fragments robustly produce polymer brushes of predictable heights and concentration profiles. The brush thickness can be tuned by the duration of growth or the enzyme density in the membranes. The system is self-renewing in that old polymers desorb and new polymers are produced. The brush can also be replenished after enzymatic removal multiple times. The large extent of the polymer interface allows for characterization of the brush architecture and for studying dynamic processes inside the brush using optical microscopy. At low ionic strengths (1 mM), we measure one of the largest polymer brushes yet reported, an average of 7.8 microns thick. For applications that require a stable brush interface, we have covalently reinforced the HA to the surfaces, and demonstrated that the brush is stable for at least two months. This self-renewing, dynamic biopolymer brush has great potential as a new biomaterial for implants, antifouling, tissue engineering and drug delivery.

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

PubMed

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.

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

PubMed

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.

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

PubMed

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.

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

PubMed

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.

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

PubMed

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

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

PubMed

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; <100 nm), and disrupted the normal organization of the microvilli as a consequence of 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.

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

Treesearch

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...

Distribution of Chains in Polymer Brushes Produced by a “Grafting From” Mechanism

DOE PAGES

Martinez, Andre P.; Carrillo, Jan-Michael Y.; Dobrynin, Andrey V.; ...

2016-01-11

The molecular weight and polydispersity of the chains in a polymer brush are critical parameters determining the brush properties. However, the characterization of polymer brushes is hindered by the vanishingly small mass of polymer present in brush layers. In this study, in order to obtain sufficient quantities of polymer for analysis, polymer brushes were grown from high surface area fibrous nylon membranes by ATRP. We synthesized the brushes with varying surface initiator densities, polymerization times, and amounts of sacrificial initiator, then cleaved from the substrate, and analyzed by GPC and NMR. Characterization showed that the surface-grown polymer chains were moremore » polydisperse and had lower average molecular weight compared to solution-grown polymers synthesized concurrently. Furthermore, the molecular weight distribution of the polymer brushes was observed to be bimodal, with a low molecular weight population of chains representing a significant mass fraction of the polymer chains at high surface initiator densities. Moreover, the origin of this low MW polymer fraction is proposed to be the termination of growing chains by recombination during the early stages of polymerization, a mechanism confirmed by molecular dynamics simulations of brush polymerization.« less

New Poly(amino acid methacrylate) Brush Supports the Formation of Well-Defined Lipid Membranes

PubMed Central

2015-01-01

A novel poly(amino acid methacrylate) brush comprising zwitterionic cysteine groups (PCysMA) was utilized as a support for lipid bilayers. The polymer brush provides a 12-nm-thick cushion between the underlying hard support and the aqueous phase. At neutral pH, the zeta potential of the PCysMA brush was ∼−10 mV. Cationic vesicles containing >25% DOTAP were found to form a homogeneous lipid bilayer, as determined by a combination of surface analytical techniques. The lipid mobility as measured by FRAP (fluorescence recovery after photobleaching) gave diffusion coefficients of ∼1.5 μm2 s–1, which are comparable to those observed for lipid bilayers on glass substrates. PMID:25746444

The In Ovo Feeding Administration (Gallus Gallus)—An Emerging In Vivo Approach to Assess Bioactive Compounds with Potential Nutritional Benefits

PubMed Central

2018-01-01

In recent years, the in ovo feeding in fertilized broiler (Gallus gallus) eggs approach was further developed and currently is widely applied in the evaluation process of the effects of functional foods (primarily plant origin compounds) on the functionality of the intestinal brush border membrane, as well as potential prebiotic properties and interactions with the intestinal microbial populations. This review collates the information of potential nutrients and their effects on the mineral absorption, gut development, brush border membrane functionality, and immune system. In addition, the advantages and limitations of the in ovo feeding method in the assessment of potential prebiotic effects of plant origin compounds is discussed. PMID:29597266

Development of a Brush Seals Program Leading to Ceramic Brush Seals

NASA Technical Reports Server (NTRS)

Hendricks, Robert C.; Flower, Ralph; Howe, Harold

1994-01-01

Some events of a U.S. Army/NASA Lewis Research Center brush seals program are reviewed, and the development of ceramic brush seals is described. Some preliminary room-temperature flow data are given, and the results of testing metallic brushes in cryogenic nitrogen are discussed.

Explicit Solvent Simulations of Friction between Brush Layers of Charged and Neutral Bottle-Brush Macromolecules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carrillo, Jan-Michael; Brown, W Michael; Dobrynin, Andrey

2012-01-01

We study friction between charged and neutral brush layers of bottle-brush macromolecules using molecular dynamics simulations. In our simulations the solvent molecules were treated explicitly. The deformation of the bottle-brush macromolecules under the shear were studied as a function of the substrate separation and shear stress. For charged bottle-brush layers we study effect of the added salt on the brush lubricating properties to elucidate factors responsible for energy dissipation in charged and neutral brush systems. Our simulations have shown that for both charged and neutral brush systems the main deformation mode of the bottle-brush macromolecule is associated with the backbonemore » deformation. This deformation mode manifests itself in the backbone deformation ratio, , and shear viscosity, , to be universal functions of the Weissenberg number W. The value of the friction coefficient, , and viscosity, , are larger for the charged bottle-brush coatings in comparison with those for neutral brushes at the same separation distance, D, between substrates. The additional energy dissipation generated by brush sliding in charged bottle-brush systems is due to electrostatic coupling between bottle-brush and counterion motion. This coupling weakens as salt concentration, cs, increases resulting in values of the viscosity, , and friction coefficient, , approaching corresponding values obtained for neutral brush systems.« less

Human neutral brush border endopeptidase EC 3.4.24.11 in urine, its isolation, characterisation and activity in renal diseases.

PubMed

Vlaskou, D; Hofmann, W; Guder, W G; Siskos, P A; Dionyssiou-Asteriou, A

2000-07-01

Human neutral brush border endopeptidase (NEP) was purified from the urine of patients suffering from acute toxic tubulointerstitial nephropathy. An enzyme preparation with specific activity of 102 Ug(-1) protein was obtained. The urinary activities of neutral endopeptidase and alanine aminopeptidase were measured in patients with renal disease and in 30 control patients, resulting in a reference range from 0.1 to 0.7 Ug(-1) creatinine and 1.4-14.1 Ug(-1) creatinine, respectively. Urine enzyme activities were highest in patients with acute tubulotoxic renal diseases. Neutral endopeptidase and alanine aminopeptidase activities were found to be 6.5- and 10-fold higher than the upper value of the reference range, respectively. Smaller increases in the rate of excretion of these enzymes (2.5- and 3.5-fold), respectively, were observed in patients suffering from acute tubular insufficiency and even lower increases, 2- and 1.5-fold, respectively, were observed in patients with chronic renal diseases. In diabetics and kidney transplant patients the enzyme excretion rates were within the reference range. Assay of both transmembrane metalloproteinases in urine may prove valuable in serving as markers for renal toxicity. Together with beta-NAG these enzymes could be employed as differentiation markers between acute and chronic tubular insufficiency.

Ureteral retrograde brush biopsy

MedlinePlus

Biopsy - brush - urinary tract; Retrograde ureteral brush biopsy cytology; Cytology - ureteral retrograde brush biopsy ... should not be performed in people with a: Urinary tract infection Blockage at or below the biopsy site ...

Mitigation of Biofilm Development on Thin-Film Composite Membranes Functionalized with Zwitterionic Polymers and Silver Nanoparticles.

PubMed

Liu, Caihong; Faria, Andreia F; Ma, Jun; Elimelech, Menachem

2017-01-03

We demonstrate the functionalization of thin-film composite membranes with zwitterionic polymers and silver nanoparticles (AgNPs) for combating biofouling. Combining hydrophilic zwitterionic polymer brushes and biocidal AgNPs endows the membrane with dual functionality: antiadhesion and bacterial inactivation. An atom transfer radical polymerization (ATRP) reaction is used to graft zwitterionic poly(sulfobetaine methacrylate) (PSBMA) brushes to the membrane surface, while AgNPs are synthesized in situ through chemical reduction of silver. Two different membrane architectures (Ag-PSBMA and PSBMA-Ag TFC) are developed according to the sequence AgNPs, and PSBMA brushes are grafted on the membrane surface. A static adhesion assay shows that both modified membranes significantly reduced the adsorption of proteins, which served as a model organic foulant. However, improved antimicrobial activity is observed for PSBMA-Ag TFC (i.e., AgNPs on top of the polymer brush) in comparison to the Ag-PSBMA TFC membrane (i.e., polymer brush on top of AgNPs), indicating that architecture of the antifouling layer is an important factor in the design of zwitterion-silver membranes. Confocal laser scanning microscopy (CLSM) imaging indicated that PSBMA-Ag TFC membranes effectively inhibit biofilm formation under dynamic cross-flow membrane biofouling tests. Finally, we demonstrate the regeneration of AgNPs on the membrane after depletion of silver from the surface of the PSBMA-Ag TFC membrane.

DNA decontamination of fingerprint brushes.

PubMed

Szkuta, Bianca; Oorschot, Roland A H van; Ballantyne, Kaye N

2017-08-01

Genetic profiling of DNA collected from fingerprints that have been exposed to various enhancement techniques is routine in many forensic laboratories. As a result of direct contact with fingermark residues during treatment, there is concern around the DNA contamination risk of dusting fingermarks with fingerprint brushes. Previous studies have demonstrated the potential for cross-contamination between evidentiary items through various mechanisms, highlighting the risk of using the same fingerprint brush to powder multiple surfaces within and between crime-scenes. Experiments were performed to assess the contamination risk of reused fingerprint brushes through the transfer of dried saliva and skin deposits from and to glass surfaces with new unused squirrel hair and fiberglass brushes. Additional new unused brushes and brushes previously used in casework were also tested for their ability to contaminate samples. In addition, the ability to eradicate DNA from used squirrel hair and fiberglass fingerprint brushes was assessed using a 1% sodium hypochlorite solution and a 5% solution of a commercially available alternative, Virkon. DNA profiling results from surfaces contacted by treated and untreated brushes were compared to determine the effectiveness of the devised cleaning protocol. Brush durability was also assessed over multiple wash/rinse/dry cycles with both agents. Varying amounts of DNA-containing material were collected and transferred by squirrel hair and fiberglass brushes, with detectability on the secondary surface dependent on the biological nature of the material being transferred. The impact of DNA contamination from dirty fingerprint brushes was most apparent in simulations involving the transfer of dried saliva and brushes previously used in casework, while minimal transfer of touch DNA was observed. Alarmingly, large quantities of DNA were found to reside on new unused squirrel hair brushes, while no DNA was detected on new unused fiberglass

Polyelectrolyte brushes on dielectric surfaces

NASA Astrophysics Data System (ADS)

Antila, Hanne; Luijten, Erik

When chains of charged polymers are grafted to a solid surface, a polyelectrolyte (PE) brush results. These types of PE assemblies have a wide range of applications ranging from fuel cells and switchable electrodes to drug delivery. Many of these applications stem from the ability of PE brushes to respond to external stimuli: the brush properties can be tuned, for example, by varying electric field, PE grafting density, pH, salt concentration or salt valency. Accordingly, deciphering the brush behavior under different conditions has been a subject of considerable experimental, theoretical, and computational research efforts. However, the effect of the dielectric properties of the substrate on the PE brush has received much less attention. We use coarse-grained molecular dynamics simulations to show how varying the dielectric mismatch between the solvent and the substrate can significantly affect the brush. We demonstrate how tuning this mismatch can either diminish or enhance the effects of other control parameters, such as pH, on the brush properties. Furthermore, we investigate how dielectric properties of the substrate affect the brush, and the ion distribution and mobility within the brush, when the brush is exposed to an electric field.

Histochemical study of lectin binding sites in fourth and fifth instar gypsy moth larval midgut epithelium

Treesearch

Algimantas P. Valaitis

2011-01-01

There is evidence that the gypsy moth, Lymantria dispar, midgut epithelial brush border membrane has membrane-bound glycoconjugates, such as BTR-270 and aminopeptidase N (APN), which function as high affinity binding sites (receptors) for the insecticidal proteins produced by Bacillus thuringiensis (Bt). As gypsy...

Osmotic and Salted Brush Phase of Polyelectrolyte Brushes

NASA Astrophysics Data System (ADS)

Helm, Christane A.; Ahrens, Heiko; Förster, Stephan

2004-03-01

Amphiphilic block copolymers consisting of a fluid hydrophobic Poly(ethyletylene) (PEE), and a Poly(styrenesulfonate) (PSS) part form monolayers at the air/water interface. With x-ray reflectivity it is shown that the hydrophobic blocks of PEE_114PSS_83 and PEE_144PSS_136 constitute a nm-thick melt, while the polyelectrolyte forms an osmotically swollen brush with counterion incorporation. A slight thickness increase on monolayer compression is found which can be explained by the strong stretching of the brushes. Only at high salt conditions (above 0.1 M), the brush shrinks and the thickness scales with the molecular area (exponent -1/3), and with the salt concentration (exponent ca. -1/5). With Grazing Incidence Diffraction, the lateral order of the polyelectrolyte chains can be detected.

Analysis of tooth brushing cycles.

PubMed

Tosaka, Yuki; Nakakura-Ohshima, Kuniko; Murakami, Nozomi; Ishii, Rikako; Saitoh, Issei; Iwase, Yoko; Yoshihara, Akihiro; Ohuchi, Akitsugu; Hayasaki, Haruaki

2014-11-01

The aim of this study was to demonstrate the effectiveness of an analysis of tooth brushing cycles using a system that measures tooth brushing motion and brushing force with an accelerometer and strain tension gage attached to a toothbrush. Mechanical plaque removal with a manual toothbrush remains the primary method of maintaining good oral hygiene for the majority of the population. Because toothbrush motion has not been fully understood, it should be clarified by analysis of tooth brushing cycles. Twenty healthy female dental hygienists participated in this study. Their tooth brushing motions were measured and analyzed using an American Dental Association-approved manual toothbrush to which a three-dimensional (3-D) accelerometer and strain tension gage were attached. 3-D motion and brushing force on the labial surface of the mandibular right central incisor and the lingual surface of the mandibular left first molar were measured, analyzed, and compared. Multilevel linear model analysis was applied to estimate variables and compare motion and forces related to the two tooth surfaces. The analysis of tooth brushing cycles was feasible, and significant differences were detected for durations and 3-D ranges of toothbrush motion as well as brushing force between the two tooth surfaces. The analysis used in this study demonstrated an ability to detect characteristics of tooth brushing motion, showing tooth brushing motion to change depending on the brushed location. These results also suggest that more detailed instructions might be required according to patient's oral condition.

Ordering nanoparticles with polymer brushes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Shengfeng; Stevens, Mark J.; Grest, Gary S.

Ordering nanoparticles into a desired super-structure is often crucial for their technological applications. We use molecular dynamics simulations to study the assembly of nanoparticles in a polymer brush randomly grafted to a planar surface as the solvent evaporates. Initially, the nanoparticles are dispersed in a solvent that wets the polymer brush. After the solvent evaporates, the nanoparticles are either inside the brush or adsorbed at the surface of the brush, depending on the strength of the nanoparticle-polymer interaction. For strong nanoparticle-polymer interactions, a 2-dimensional ordered array is only formed when the brush density is finely tuned to accommodate a singlemore » layer of nanoparticles. When the brush density is higher or lower than this optimal value, the distribution of nanoparticles shows large fluctuations in space and the packing order diminishes. For weak nanoparticle-polymer interactions, the nanoparticles order into a hexagonal array on top of the polymer brush as long as the grafting density is high enough to yield a dense brush. As a result, an interesting healing effect is observed for a low-grafting-density polymer brush that can become more uniform in the presence of weakly adsorbed nanoparticles.« less

Ordering nanoparticles with polymer brushes

NASA Astrophysics Data System (ADS)

Cheng, Shengfeng; Stevens, Mark J.; Grest, Gary S.

2017-12-01

Ordering nanoparticles into a desired super-structure is often crucial for their technological applications. We use molecular dynamics simulations to study the assembly of nanoparticles in a polymer brush randomly grafted to a planar surface as the solvent evaporates. Initially, the nanoparticles are dispersed in a solvent that wets the polymer brush. After the solvent evaporates, the nanoparticles are either inside the brush or adsorbed at the surface of the brush, depending on the strength of the nanoparticle-polymer interaction. For strong nanoparticle-polymer interactions, a 2-dimensional ordered array is only formed when the brush density is finely tuned to accommodate a single layer of nanoparticles. When the brush density is higher or lower than this optimal value, the distribution of nanoparticles shows large fluctuations in space and the packing order diminishes. For weak nanoparticle-polymer interactions, the nanoparticles order into a hexagonal array on top of the polymer brush as long as the grafting density is high enough to yield a dense brush. An interesting healing effect is observed for a low-grafting-density polymer brush that can become more uniform in the presence of weakly adsorbed nanoparticles.

Ordering nanoparticles with polymer brushes

DOE PAGES

Cheng, Shengfeng; Stevens, Mark J.; Grest, Gary S.

2017-12-08

Ordering nanoparticles into a desired super-structure is often crucial for their technological applications. We use molecular dynamics simulations to study the assembly of nanoparticles in a polymer brush randomly grafted to a planar surface as the solvent evaporates. Initially, the nanoparticles are dispersed in a solvent that wets the polymer brush. After the solvent evaporates, the nanoparticles are either inside the brush or adsorbed at the surface of the brush, depending on the strength of the nanoparticle-polymer interaction. For strong nanoparticle-polymer interactions, a 2-dimensional ordered array is only formed when the brush density is finely tuned to accommodate a singlemore » layer of nanoparticles. When the brush density is higher or lower than this optimal value, the distribution of nanoparticles shows large fluctuations in space and the packing order diminishes. For weak nanoparticle-polymer interactions, the nanoparticles order into a hexagonal array on top of the polymer brush as long as the grafting density is high enough to yield a dense brush. As a result, an interesting healing effect is observed for a low-grafting-density polymer brush that can become more uniform in the presence of weakly adsorbed nanoparticles.« less

Turbine-Driven Pipe-Cleaning Brush

NASA Technical Reports Server (NTRS)

Werlink, Rudy J.; Rowell, David E.

1994-01-01

Simple pipe-cleaning device includes small turbine wheel axially connected, by standoff, to circular brush. Turbine wheel turns on hub bearing attached to end of upstream cable. Turbine-and-brush assembly inserted in pipe with cable trailing upstream and brush facing downstream. Water or cleaning solution pumped through pipe. Cable held at upstream end, so it holds turbine and brush in pipe at location to be cleaned. Flow in pipe turns turbine, which turns wheel, producing desired cleaning action. In addition to brushing action, device provides even mixing of cleaning solution in pipe.

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

PubMed

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.

Brush seals for cryogenic applications

NASA Astrophysics Data System (ADS)

Proctor, Margaret P.

1994-07-01

This viewgraph presentation presents test results of brush seals for cryogenic applications. Leakage for a single brush seal was two to three times less than for a 12-tooth labyrinth seal. The maximum temperature rise for a single brush seal was less than 50 R and occurred at 25 psid across the seal and 35,000 rpm. A static blowout test demonstrated sealing capability up to 550 psid. The seal limit was not obtained. The power loss for a single brush at 35,000 rpm and 175 psid was 2.45 hp. Two brushes far apart leak less than two brushes tight packed. Rotor wear was approximately 0.00075 mils and bristle wear was 1-3 mils after 4-1/2 hours.

``Smart'' Surfaces of Polymer Brushes

NASA Astrophysics Data System (ADS)

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.

Cavitation during wire brushing

NASA Astrophysics Data System (ADS)

Li, Bo; Zou, Jun; Ji, Chen

2016-11-01

In our daily life, brush is often used to scrub the surface of objects, for example, teeth, pots, shoes, pool, etc. And cleaning rust and stripping paint are accomplished using wire brush. Wire brushes also can be used to clean the teeth for large animals, such as horses, crocodiles. By observing brushing process in water, we capture the cavitation phenomenon on the track of moving brush wire. It shows that the cavitation also can affect the surface. In order to take clear and entire pictures of cavity, a simplified model of one stainless steel wire brushing a boss is adopted in our experiment. A transparent organic tank filled with deionized water is used as a view box. And a high speed video camera is used to record the sequences. In experiment, ambient pressure is atmospheric pressure and deionized water temperature is kept at home temperature. An obvious beautiful flabellate cavity zone appears behind the moving steel wire. The fluctuation of pressure near cavity is recorded by a hydrophone. More movies and pictures are used to show the behaviors of cavitation bubble following a restoring wire. Beautiful tracking cavitation bubble cluster is captured and recorded to show.

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

Treesearch

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...

Glucose monitoring using a polymer brush modified polypropylene hollow fiber-based hydraulic flow sensor.

PubMed

Fortin, Nicolas; Klok, Harm-Anton

2015-03-04

Tight regulation of blood glucose levels of diabetic patients requires durable and robust continuous glucose sensing schemes. This manuscript reports the fabrication of ultrathin, phenylboronic acid (PBA) functionalized polymer brushes that swell upon glucose binding and which were integrated as the sensing interface in a new polypropylene hollow fiber (PPHF)-based hydraulic flow glucose sensor prototype. The polymer brushes were prepared via surface-initiated atom transfer radical polymerization of sodium methacrylate followed by postpolymerization modification with 3-aminophenyl boronic acid. In a first series of experiments, the glucose-response of PBA-functionalized poly(methacrylic acid) (PMAA) brushes grafted from planar silicon surfaces was investigated by quartz crystal microbalance with dissipation (QCM-D) and atomic force microscopy (AFM) experiments. The QCM-D experiments revealed a more or less linear change of the frequency shift for glucose concentrations up to ∼10 mM and demonstrated that glucose binding was completely reversible for up to seven switching cycles. The AFM experiments indicated that glucose binding was accompanied by an increase in the film thickness of the PBA functionalized PMAA brushes. The PBA functionalized PMAA brushes were subsequently grafted from the surface of PPHF membranes. The hydraulic permeability of these porous fibers depends on the thickness and swelling of the PMAA brush coating. PBA functionalized brush-coated PPHFs showed a decrease in flux upon exposure to glucose, which is consistent with swelling of the brush coating. Because they avoid the use of enzymes and do not rely on an electrochemical transduction scheme, these PPHF-based hydraulic flow sensors could represent an interesting alternative class of continuous glucose sensors.

Carbachol regulation of rabbit ileal brush border Na+–H+ exchanger 3 (NHE3) occurs through changes in NHE3 trafficking and complex formation and is Src dependent

PubMed Central

Li, Xuhang; Zhang, Huiping; Cheong, Alice; Yueping Chen, Sharon Leu; Elowsky, Christian G; Donowitz, Mark

2004-01-01

The epithelial brush border membrane (BBM) Na+–H+ exchanger 3 (NHE3) is the major transport protein responsible for ileal electroneutral Na+ absorption. We have previously shown that ileal BBM NHE3 activity is rapidly inhibited by carbachol, an agonist that mimics cholinergic activation in digestion. In this study, we investigated the mechanisms involved in this NHE3 inhibition. Carbachol decreased the amount of ileal Na+ absorptive cell BBM NHE3 within 10 min of exposure. Based on OptiPrep gradient centrifugation, carbachol increased the amount of NHE3 in early endosomes and decreased the amount of NHE3 in BBM, consistent with effects on NHE3 trafficking. The decrease in BBM NHE3 occurred in the detergent-soluble BBM fraction with no change in the amount of NHE3 in the BBM detergent-resistant membranes. The size of BBM NHE3 complexes increased in carbachol-exposed ileum, as studied with sucrose gradient centrifugation. The NHE3 complex size increased in the total BBM, but did not change in the detergent-soluble fraction. This suggests that carbachol treatment enhanced the association of proteins with NHE3 complexes specifically in the detergent-resistant fraction of ileal BBM. NHERF2, α-actinin-4 and protein kinase C were among those NHE3-associated proteins because they were more efficiently coimmunoprecipitated from total BBM after carbachol treatment. Moreover, Src was involved in the carbachol-mediated inhibition since: (1) c-Src was rapidly activated in the detergent-resistant membranes by carbachol; and (2) carbachol inhibition of ileal Na+ absorption was completely abolished by the Src family inhibitor 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP2). Moreover, the carbachol-induced increase in the size of NHE3-containing complexes was reversed by PP2. These data demonstrate that regulation of NHE3 activity by carbachol can be achieved at several interrelated levels: (1) the subcellular level, at which NHE3 is rapidly endocytosed

Increasing operational life of brush-contact device in the turbine generator due to using lubricating molybdenum disulphide brushes

NASA Astrophysics Data System (ADS)

Izotov, A. I.; Fominykh, A. A.; Nikulin, S. V.; Prokoshev, D. K.; Legoti, A. B.; Timina, N. V.

2018-01-01

A way of reducing irregular current distribution in multi-brush systems of sliding current transfer with its wear reduction due to installing lubricating molybdenum disulphide brushes on slip rings to ensure a greasing nano-sized cover on the slip ring surface is proposed. The authors give the results of industrial tests estimated on the performance effectiveness of lubricating brushes on slip rings of the TBB-320-2UZ-type turbine generator. The results showed that the lubricating brushes reduce a) the wear of 6110 OM+M and EG2AF+M brushes by 1.2 and 2.1 times respectively, b) current distribution irregularity in parallel operating brushes due to stabilizing the contact arc, and c) the temperature of the electrical brush-contact device due to the friction reduction in brushes.

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

PubMed

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

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

PubMed

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.

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

PubMed Central

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

Social ranking effects on tooth-brushing behaviour.

PubMed

Maltby, John; Paterson, Kevin; Day, Liz; Jones, Ceri; Kinnear, Hayley; Buchanan, Heather

2016-05-01

A tooth-brushing social rank hypothesis is tested suggesting tooth-brushing duration is influenced when individuals position their behaviour in a rank when comparing their behaviour with other individuals. Study 1 used a correlation design, Study 2 used a semi-experimental design, and Study 3 used a randomized intervention design to examine the tooth-brushing social rank hypothesis in terms of self-reported attitudes, cognitions, and behaviour towards tooth-brushing duration. Study 1 surveyed participants to examine whether the perceived health benefits of tooth-brushing duration could be predicted from the ranking of each person's tooth-brushing duration. Study 2 tested whether manipulating the rank position of the tooth-brushing duration influenced participant-perceived health benefits of tooth-brushing duration. Study 3 used a longitudinal intervention method to examine whether messages relating to the rank positions of tooth-brushing durations causally influenced the self-report tooth-brushing duration. Study 1 demonstrates that perceptions of the health benefits from tooth-brushing duration are predicted by the perceptions of how that behaviour ranks in comparison to other people's behaviour. Study 2 demonstrates that the perceptions of the health benefits of tooth-brushing duration can be manipulated experimentally by changing the ranked position of a person's tooth-brushing duration. Study 3 experimentally demonstrates the possibility of increasing the length of time for which individuals clean their teeth by focusing on how they rank among their peers in terms of tooth-brushing duration. The effectiveness of interventions using social-ranking methods relative to those that emphasize comparisons made against group averages or normative guidelines are discussed. What is already known on this subject? Individual make judgements based on social rank information. Social rank information has been shown to influence positive health behaviours such as exercise

Nanostructured bio-functional polymer brushes.

PubMed

Padeste, Celestino; Farquet, Patrick; Potzner, Christian; Solak, Harun H

2006-01-01

Structured poly(glycidyl methracrylate) (poly-GMA) brushes have been grafted onto flexible fluoro-polymer films using a radiation grafting process. The reactive epoxide of poly-GMA provides the basis for a versatile biofunctionalization of the grafted brushes. Structure definition by extreme ultraviolet (EUV) exposure allowed nanometer-scale resolution of periodic patterns. By variation of the exposure dose the height of the grafted structures can be adapted in a wide range. Derivatization of the grafted brushes included reaction with various amines with different side chains, hydrolysis of the epoxide to diols to increase protein resistance and introduction of ionic groups to yield poly-electrolytes. As an example for biofunctionalization, biotin was linked to the grafted brush and biofunctionality was demonstrated in a competitive biotin-streptavidin assay. In this article we also present a brief review of other approaches to obtain structured biofunctional polymer brushes.

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

PubMed

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

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. Copyright © 2016 Elsevier B.V. All rights reserved.

Vaccination of sheep against haemonchosis with H11, a gut membrane-derived protective antigen from the adult parasite: prevention of the periparturient rise and colostral transfer of protective immunity.

PubMed

Andrews, S J; Hole, N J; Munn, E A; Rolph, T P

1995-07-01

Pregnant ewes were immunised with a fraction highly enriched in the membrane glycoprotein antigen H11, isolated from the intestinal brush border of adult Haemonchus contortus. Immunity induced by immunisation was able to abolish almost completely (98-99%) the worm egg output from pregnant ewes challenged with ca. 10,000 infective larvae of H. contortus during the last trimester. Furthermore, lambs born and reared on vaccinated ewes had substantial antibody levels to H11 derived from maternal transfer. This antibody conferred moderate protection against a bolus challenge of ca. 3000 infective larvae of H. contortus in 5-week-old lambs.

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

PubMed

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.

Brush seal numerical simulation: Concepts and advances

NASA Technical Reports Server (NTRS)

Braun, M. J.; Kudriavtsev, V. V.

1994-01-01

The development of the brush seal is considered to be most promising among the advanced type seals that are presently in use in the high speed turbomachinery. The brush is usually mounted on the stationary portions of the engine and has direct contact with the rotating element, in the process of limiting the 'unwanted' leakage flows between stages, or various engine cavities. This type of sealing technology is providing high (in comparison with conventional seals) pressure drops due mainly to the high packing density (around 100 bristles/sq mm), and brush compliance with the rotor motions. In the design of modern aerospace turbomachinery leakage flows between the stages must be minimal, thus contributing to the higher efficiency of the engine. Use of the brush seal instead of the labyrinth seal reduces the leakage flow by one order of magnitude. Brush seals also have been found to enhance dynamic performance, cost less, and are lighter than labyrinth seals. Even though industrial brush seals have been successfully developed through extensive experimentation, there is no comprehensive numerical methodology for the design or prediction of their performance. The existing analytical/numerical approaches are based on bulk flow models and do not allow the investigation of the effects of brush morphology (bristle arrangement), or brushes arrangement (number of brushes, spacing between them), on the pressure drops and flow leakage. An increase in the brush seal efficiency is clearly a complex problem that is closely related to the brush geometry and arrangement, and can be solved most likely only by means of a numerically distributed model.

Application of tooth brushing behavior to active rest.

PubMed

Sadachi, Hidetoshi; Murakami, Yoshinori; Tonomura, Manabu; Yada, Yukihiro; Simoyama, Ichiro

2010-01-01

We evaluated the usefulness of tooth brushing with toothpaste as active rest using the flicker value as a physiological parameter and a subjective questionnaire as a psychological parameter. Seventeen healthy, right-handed subjects (12 males and 5 females) aged 22.5 +/- 1.5 yr (mean +/- standard deviation) were randomly divided into tooth brushing with toothpaste (N=9) and non-tooth brushing groups (N=8). The subjects performed a serial calculation task for 20 min using personal computers. Subsequently, the tooth brushing group brushed their teeth, and the flicker value and mood were compared before and after the tooth brushing. The flicker value significantly increased in the tooth brushing group compared with the non-tooth brushing group (p<0.05). Concerning the mood, in the tooth brushing group, the incidence of a "feeling of being refreshed" significantly increased (p<0.05), that of "concentration power" or a "feeling of clear-headedness" tended to increase (p<0.1), and that of "lassitude" or "sleepiness" significantly decreased (p<0.01). Somatosensory stimulation and intraoral tactile stimulation during tooth brushing activated cerebral activity, producing refreshing effects. These results suggest the applicability of tooth brushing to active rest.

Brush Seals for Improved Steam Turbine Performance

NASA Technical Reports Server (NTRS)

Turnquist, Norman; Chupp, Ray; Baily, Fred; Burnett, Mark; Rivas, Flor; Bowsher, Aaron; Crudgington, Peter

2006-01-01

GE Energy has retrofitted brush seals into more than 19 operating steam turbines. Brush seals offer superior leakage control compared to labyrinth seals, owing to their compliant nature and ability to maintain very tight clearances to the rotating shaft. Seal designs have been established for steam turbines ranging in size from 12 MW to over 1200 MW, including fossil, nuclear, combined-cycle and industrial applications. Steam turbines present unique design challenges that must be addressed to ensure that the potential performance benefits of brush seals are realized. Brush seals can have important effects on the overall turbine system that must be taken into account to assure reliable operation. Subscale rig tests are instrumental to understanding seal behavior under simulated steam-turbine operating conditions, prior to installing brush seals in the field. This presentation discusses the technical challenges of designing brush seals for steam turbines; subscale testing; performance benefits of brush seals; overall system effects; and field applications.

Saccharomyces boulardii upgrades cellular adaptation after proximal enterectomy in rats

PubMed Central

Buts, J; De Keyser, N; Marandi, S; Hermans, D; Sokal, E; Chae, Y; Lambotte, L; Chanteux, H; Tulkens, P

1999-01-01

BACKGROUND—Saccharomyces boulardii is a non-pathogenic yeast which exerts trophic effects on human and rat small intestinal mucosa.
AIMS—To examine the effects of S boulardii on ileal adaptation after proximal enterectomy in rats.
METHODS—Wistar rats, aged eight weeks, underwent 60% proximal resection or transection and received by orogastric intubation either 1 mg/g body wt per day lyophilised S boulardii or the vehicle for seven days. The effects on ileal mucosal adaptation were assessed eight days after surgery.
RESULTS—Compared with transection, resection resulted in mucosal hyperplasia with significant decreases in the specific and total activities of sucrase, lactase, and maltase. Treatment of resected animals with S boulardii had no effect on mucosal hyperplasia but did upgrade disaccharidase activities to the levels of the transected group. Enzyme stimulation by S boulardii was associated with significant increases in diamine oxidase activity and mucosal polyamine concentrations. Likewise, sodium dependent D-glucose uptake by brush border membrane vesicles, measured as a function of time and glucose concentration in the incubation medium, was significantly (p<0.05) increased by 81% and three times respectively in the resected group treated with S boulardii. In agreement with this, expression of the sodium/glucose cotransporter-1 in brush border membranes of resected rats treated with S boulardii was enhanced twofold compared with resected controls.
CONCLUSION—Oral administration of S boulardii soon after proximal enterectomy improves functional adaptation of the remnant ileum.


Keywords: Saccharomyces boulardii; intestine; adaptation; polyamines; brush border membrane enzymes; glucose uptake PMID:10369710

Proton conduction of polyAMPS brushes on titanate nanotubes

PubMed Central

Feng, Jun; Huang, Yaqin; Tu, Zhengkai; Zhang, Haining; Pan, Mu; Tang, Haolin

2014-01-01

Proton conducting materials having reasonable proton conductivity at low humidification conditions are critical for decrease in system complexity and improvement of power density for polymer electrolyte membrane fuel cells. This study shows that polyelectrolyte brushes on titanate nanotubes formed through surface-initiated free radical polymerization exhibit less humidity-dependent proton conduction because of the high grafting density of polymer electrolyte chains and well-distribution of ionic groups. The results described in this study provide an idea for design of new proton conductors with effective ion transport served at relatively low humidification levels. PMID:25169431

The in ovo feeding administration (gallus gallus)-an emerging in vivo approach to assess bioactive compounds with potential nutritional benefits

USDA-ARS?s Scientific Manuscript database

In recent years, the in ovo feeding in fertilized broiler (Gallus gallus) eggs approach was further developed and currently is widely applied in the evaluation process of the effects of functional foods (primarily plant origin compounds) on the functionality of the intestinal brush border membrane, ...

Bacillus thuringiensis pore-forming toxins trigger massive shedding of GPI-anchored aminopeptidase N from gypsy moth midgut epithelial cells

Treesearch

Algimantas P. Valaitis

2008-01-01

The insecticidal Cry proteins produced by Bacillus thuringiensis strains are pore-forming toxins (PFTs) that bind to the midgut brush border membrane and cause extensive damage to the midgut epithelial cells of susceptible insect larvae. Force-feeding B. thuringiensis PFTs to Lymantria dispar larvae elicited...

Polymer absorption in dense polymer brushes vs. polymer adsorption on the brush-solvent interface

NASA Astrophysics Data System (ADS)

Milchev, Andrey; Binder, Kurt

2014-06-01

Molecular-dynamics simulations of a coarse-grained model of a dense brush of flexible polymers (of type A) interacting with a long flexible macromolecule (of type B) are presented, considering the case of an attractive AB interaction, while effective interactions between AA and BB pairs of monomers are repulsive. Varying the strength \\varepsilon_{AB} of the attraction between unlike monomers, an adsorption transition at some critical value \\varepsilon^c_{AB} is found, where the B-chain is bound to the brush-solvent interface, similar to the adsorption on a planar solid substrate. However, when \\varepsilon_{AB} is much higher than \\varepsilon^c_{AB} , the long macromolecule is gradually “sucked in” the brush, developing many pieces that are locally stretched in the z-direction perpendicular to the substrate, in order to fit between the brush chains. The resulting hairpin-like structures of the absorbed chain shows up via oscillatory decay of the bond vector autocorrelation function. Chain relaxation is only possible via reptation.

Structure of Weakly Charged Polyelectrolyte Brushes: Monomer Density Profiles

NASA Astrophysics Data System (ADS)

Borisov, O. V.; Zhulina, E. B.

1997-03-01

The internal structure (the monomer density profiles) of weakly charged polyelectrolyte brushes of different morphologies has been analyzed on the basis of the self-consistent-field approach. In contrast to previous studies based on the local electroneutrality approximation valid for sufficiently strongly charged or densely grafted (“osmotic") brushes we consider the opposite limit of sparse brushes which are unable to retain the counterions inside the brush. We have shown that an exact analytical solution of the SCF-equations is available in the case of a planar brush. In contrast to Gaussian monomer density profile known for “osmotic" polyelectrolyte brushes we have found that weakly charged brushes are characterized by constant monomer density. At the same time free ends of grafted polyions are distributed throughout the brush. Thus, the structural cross-over between polyelectrolyte “mushrooms" and dense brush regimes is established.

Anthrax Cases Associated with Animal-Hair Shaving Brushes.

PubMed

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.

Friction between Polymer Brushes

NASA Astrophysics Data System (ADS)

Sokoloff, Jeffrey

2006-03-01

A polymer brush consists of a surface with a fairly concentrated coating of polymer chains, each one of which has one of its ends tightly bound to the surface. They serve as extremely effective lubricant, producing friction coefficients as low as 0.001 or less! Polymer brushes are a promising way to reduce friction to extremely low values. They have the disadvantage, however, that they must be immersed in a liquid solvent in order to function as a lubricant. The presence of a solvent is believed to result in osmotic pressure which partially supports the load. The density profile of a polymer brush (i.e., the density of monomers as a function of distance from the surface to which the polymers are attached) is well established. What is not understood is how the interaction of polymer brush coated surfaces in contact with each other is able to account for the details of the observed low friction. For example, molecular dynamics studies generally do not predict static friction, whereas surface force apparatus measurements due to Tadmor, et. al., find that there is static friction. This is the topic of the present presentation.

Interaction between two polyelectrolyte brushes.

PubMed

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.

Phase behavior of ternary polymer brushes

DOE PAGES

Simocko, Chester K.; Frischknecht, Amalie L.; Huber, Dale L.

2016-01-07

Ternary polymer brushes consisting of polystyrene, poly(methyl methacrylate), and poly(4-vinylpyridine) have been synthesized. These brushes laterally phase separate into several distinct phases and can be tailored by altering the relative polymer composition. Self-consistent field theory has been used to predict the phase diagram and model both the horizontal and vertical phase behavior of the polymer brushes. As a result, all phase behaviors observed experimentally correlate well with the theoretical model.

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

PubMed

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.

Brush seals for turbine engine fuel conservation

NASA Astrophysics Data System (ADS)

Sousa, Mike

1994-07-01

The program objective is to demonstrate brush seals for replacing labyrinth seals in turboprop engines. The approach taken was to design and procure brush seals with assistance from Sealol, modify and instrument an existing T407 low pressure turbine test rig, replace inner balance piston and outer balance piston labyrinth seals with brush seals, conduct cyclic tests to evaluate seal leakage at operating pressures and temperatures, and evaluate effect of seal pack width and rotor eccentricity. Results are presented in viewgraph format and show that brush seals offer performance advantages over labyrinth seals.

Nanopatterned polymer brushes: conformation, fabrication and applications.

PubMed

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

2016-01-14

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.

Nanopatterned polymer brushes: conformation, fabrication and applications

NASA Astrophysics Data System (ADS)

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.

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.

PubMed

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 < 0.001) reductions in gingivitis and plaque measures relative to baseline. The oscillating-rotating,brush with the novel brush head demonstrated statistically significantly (P < 0.05) greater reductions in all 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.

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

USGS Publications Warehouse

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.

Nonlinearity in the rotational dynamics of Haidinger's brushes

NASA Astrophysics Data System (ADS)

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.

Bidirectional Brush Seals

NASA Technical Reports Server (NTRS)

Hendricks, Robert C.; Wilson, Jack; Wu, Tom; Flower, Ralph

1997-01-01

Presented is a study of the use of a set of I.D./O.D. bidirectional press seals to reduce the leakage losses in a wave rotor. Relative to the baseline configuration, data indicate the use of brush seals enhanced wave rotor efficiency from 36 to 45 percent at low leakages (small rotor endwall gap spacings) and from 15 to 33 percent at high leakages (larger endwall gap spacings). These brush seals are capable of sealing positive or negative pressure drops with respect to the axial direction. Surface tribology for these tests suggested little evidence of grooving although the bristles appeared polished.

Elasticity of biomembranes studied by dynamic light scattering

NASA Astrophysics Data System (ADS)

Fujime, Satoru; Miyamoto, Shigeaki

1991-05-01

Combination of osmotic swelling and dynamic light scattering makes it possible to measure the elastic modulus of biomembranes. By this technique we have observed a drastic increase in membrane flexibility on activation of Na/glucose cotransporters in membrane vesicles prepared from brush-borders of rat small intestine and on activation by micromolar [Ca2] of exocytosis in secretory granules isolated from rat pancreatic acinar cells and bovine adrenal chromaffin cells. 1 .

Surface friction of hydrogels with well-defined polyelectrolyte brushes.

PubMed

Ohsedo, Yutaka; Takashina, Rikiya; Gong, Jian Ping; Osada, Yoshihito

2004-08-03

Hydrogels of poly(2-hydroxyethyl methacrylate) (PHEMA) with well-defined polyelectrolyte brushes of poly(sodium 4-styrenesulfonate) (PNaSS) of various molecular weights were synthesized, keeping the distance between the polymer brushes constant at ca. 20 nm. The effect of polyelectrolyte brush length on the sliding friction against a glass plate, an electrorepulsive solid substrate, was investigated in water in a velocity range of 7.5 x 10(-5) to 7.5 x 10(-2) m/s. It is found that the presence of polymer brush can dramatically reduce the friction when the polymer brushes are short. With an increase in the length of the polymer brush, this drag reduction effect only works at a low sliding velocity, and the gel with long polymer brushes even shows a higher friction than that of a normal network gel at a high sliding velocity. The strong polymer length and sliding velocity dependence indicate a dynamic mechanism of the polymer brush effect.

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

Treesearch

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...

Biological Activity of Bacillus thuringiensis and Associated Toxins against the Asian Longhorned Beetle (Coleoptera: Cerambycidae)

Treesearch

Vincent D' amico; John D. Podgwaite; Sara Duke; Sara Duke

2004-01-01

Bacillus thuringiensis Berliner var. tenebrionis and B. thuringiensis toxins were assayed against larval and adult Asian longhorned beetles, Anoplophora glabripennis (A. glabripennis). Preliminary in vitro assays showed some toxins to be active on whole midgut preparations in voltage clamp assays and in assays on brush border membrane vesicles formed from midgut...

Nanostructured polymer brushes.

PubMed

Schmelmer, Ursula; Paul, Anne; Küller, Alexander; Steenackers, Marin; Ulman, Abraham; Grunze, Michael; Gölzhäuser, Armin; Jordan, Rainer

2007-03-01

Nanopatterned polymer brushes with sub-50-nm resolution were prepared by a combination of electron-beam chemical lithography (EBCL) of self-assembled monolayers (SAMs) and surface-initiated photopolymerization (SIPP). As a further development of our previous work, selective EBCL was performed with a highly focused electron beam and not via a mask, to region-selectively convert a SAM of 4'-nitro-1,1'-biphenyl-4-thiol to defined areas of crosslinked 4'-amino-1,1'-biphenyl-4-thiol. These "written" structures were then used to prepare surface-bonded, asymmetric, azo initiator sites of 4'-azomethylmalonodinitrile-1,1'-biphenyl-4-thiol. In the presence of bulk styrene, SIPP amplified the primary structures of line widths from 500 to 10 nm to polystyrene structures of line widths 530 nm down to approximately 45 nm at a brush height of 10 or 7 nm, respectively, as measured by scanning electron microscopy and atomic force microscopy (AFM). The relative position of individual structures was within a tolerance of a few nanometers, as verified by AFM. At line-to-line spacings down to 50-70 nm, individual polymer brush structures are still observable. Below this threshold, neighboring structures merge due to chain overlap.

Some metallographic results for brush bristles and brush segments of a shroud ring brush seal tested in a T-700 engine

NASA Technical Reports Server (NTRS)

Hendricks, Robert C.; Griffin, Thomas A.; Bobula, George A.; Bill, Robert C.; Hull, David R.; Csavina, Kristine R.

1994-01-01

Post-test investigation of a T-700 engine brush seal found regions void of bristles ('yanked out'), regions of bent-over bristles near the inlet, some 'snapped' bristles near the fence, and a more uniform smeared bristle interface between the first and last axial rows of bristles. Several bristles and four brush segments were cut from the brush seal, wax mounted, polished, and analyzed. Metallographic analysis of the bristle near the rub tip showed tungsten-rich phases uniformly distributed throughout the bristle, no apparent change within 1 mu m of the interface, and possibly a small amount of titanium, which would represent a transfer from the rotor. Analysis of the bristle wear face showed nonuniform tungsten, which is indicative of material resolidification. The cut end contained oxides and internal fractures; the worn end was covered with oxide scale. Material losses due to wear and elastoplastic deformation within the shear zone and third-body lubrication effects in the contact zone are discussed.

Tooth-brushing behaviour in 6-12 year olds.

PubMed

Sandström, Anna; Cressey, Janet; Stecksén-Blicks, Christina

2011-01-01

A common clinical finding is that many schoolchildren display a nonacceptable oral hygiene. To evaluate the tooth-brushing behaviour in children aged 6-12 years. The study used a cross-sectional descriptive design. Children aged 6, 8, 10, and 12 years in an elementary school in a middle class area in Umeå, a city in northern Sweden, were invited and 82 (82%) consented. Visible plaque on buccal surfaces of incisors and canines was recorded from photographs of the participant's teeth before and after brushing using the scores of the Green and Vermillion Oral Hygiene Index. Brushing technique was recorded with a video camera. A questionnaire was used to collect data about oral hygiene habits at home. The ratio between the sum of plaque scores after and before brushing was statistically significantly higher in the 6-year-old group compared with the 10-year olds, (P < 0.05). There was a negative correlation between time spent for brushing and the ratio between the sum of plaque scores after and before brushing (r = -0.31, P < 0.01). The lowest correlation was displayed in the youngest age group (r = 0.07, P > 0.05). Six-year olds spent statistically significantly less time for brushing than older children (P < 0.05). Plaque removal from buccal surfaces from brushing was poor and averaged 19% for 6-year olds and 30% for older children. The results of brushing for children aged 8-12 years could benefit from increasing tooth-brushing time. Children could be given an increasing responsibility from 7 to 8 year of age but parental help is motivated up to 10 years of age. © 2010 The Authors. International Journal of Paediatric Dentistry © 2010 BSPD, IAPD and Blackwell Publishing Ltd.

Voltage-induced swelling and deswelling of weak polybase brushes.

PubMed

Weir, Michael P; Heriot, Sasha Y; Martin, Simon J; Parnell, Andrew J; Holt, Stephen A; Webster, John R P; Jones, Richard A L

2011-09-06

We have investigated a novel method of remotely switching the conformation of a weak polybase brush using an applied voltage. Surface-grafted polyelectrolyte brushes exhibit rich responsive behavior and show great promise as "smart surfaces", but existing switching methods involve physically or chemically changing the solution in contact with the brush. In this study, high grafting density poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes were grown from silicon surfaces using atom transfer radical polymerization. Optical ellipsometry and neutron reflectivity were used to measure changes in the profiles of the brushes in response to DC voltages applied between the brush substrate and a parallel electrode some distance away in the surrounding liquid (water or D(2)O). Positive voltages were shown to cause swelling, while negative voltages in some cases caused deswelling. Neutron reflectometry experiments were carried out on the INTER reflectometer (ISIS, Rutherford Appleton Laboratory, UK) allowing time-resolved measurements of polymer brush structure. The PDMAEMA brushes were shown to have a polymer volume fraction profile described by a Gaussian-terminated parabola both in the equilibrium and in the partially swollen states. At very high positive voltages (in this study, positive bias means positive voltage to the brush-bearing substrate), the brush chains were shown to be stretched to an extent comparable to their contour length, before being physically removed from the interface. Voltage-induced swelling was shown to exhibit a wider range of brush swelling states in comparison to pH switching, with the additional advantages that the stimulus is remotely controlled and may be fully automated. © 2011 American Chemical Society

Sugar uptake by intestinal basolateral membrane vesicles.

PubMed

Wright, E M; van Os, C H; Mircheff, A K

1980-03-27

A high yield of membrane vesicles was prepared from the basolateral surface of rat intestinal cells using an N2 cavitation bomb and density gradient centrifugation. The membranes were enriched 10-fold and were free of significatn contamination by brush border membranes and mitochondria. The rate of D-E114C]glucose and L-E13H]glucose uptake into the vesicle was measured using a rapid filtration technique. D-Glucose equilibrated within the vesicles with a half-time 1/25th that for L-glucose. The stereospecific uptake exhibited saturation kinetics with a Km of approx. 44 mM and a V of approx. 110 nmol . mg-1 min-1 at 10 degrees C. The activation energy for the process was 14 kcal . mol-1 below 15 degrees C and it approached 3 kcal . mol-1 above 22 degrees C. Carrier-mediated uptake was eliminated in the presence of 1 mM HgCl2 and 0.5 mM phloretin. The rate of transport was unaffected by the absence or presence of sodium concentration gradients. Competition studies demonstrated that all sugars with the D-glucose pyranose ring chair conformation shared the transport system, and that, with the possible exception of the -OH group at carbon No. 1, there were no specific requirements for an equatorial -OH group at any position in the pyranose ring. In the case of alpha-methyl-D-glucoside its inability to share the D-glucose transport system may be due to steric hindrance posed by the -OCH3 group rather than by a specific requirement for a free hydroxyl group at the position in the ring. It is concluded that sugars are transported across the basolateral membrane of the intestinal epithelium by a facilitated diffusion system reminiscent of that in human red blood cells.

Characterization of Small DC Brushed and Brushless Motors

DTIC Science & Technology

2013-03-01

8 Figure 6. Torque vs. RPM for a SS7 -1.7-1 brushed motor...9 Figure 7. Efficiency vs. motor power output for SS7 -1.7-1 brushed motor...10 Figure 8. Efficiency vs. RPM for SS7 -1.7-1 brushed motor. ........................................................10 Figure 9

Tooth brushing inhibits oral bacteria in dogs.

PubMed

Watanabe, Kazuhiro; Hayashi, Kotaro; Kijima, Saku; Nonaka, Chie; Yamazoe, Kazuaki

2015-10-01

In this study, scaling, polishing and daily tooth brushing were performed in 20 beagle dogs, and the number of oral bacteria was determined using a bacterial counter. The dogs were randomized into the scaling (S), scaling + polishing (SP), scaling + tooth daily brushing (SB) and scaling + polishing + tooth daily brushing (SPB) groups. Samples were collected from the buccal surface of the maxillary fourth premolars of the dogs immediately after scaling and every week thereafter from weeks 1 to 8. Throughout the study, the number of bacteria was significantly lower in the SB and SPB groups compared with the S group. The findings suggest that daily tooth brushing inhibited oral bacterial growth in the dogs.

Water driven turbine/brush pipe cleaner

NASA Technical Reports Server (NTRS)

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.

Dual wound dc brush motor gearhead

NASA Technical Reports Server (NTRS)

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.

Design and Testing of High Performance Brushes.

DTIC Science & Technology

1982-03-01

specific types, namely metal fiber brushes and met- al foil brushes, have been constructed and tested, and a theory has been developed which accounts for...combining electric- al measurements with mechanical investigations and optical observations. Since we now have reason to rely confidently on the theory of...reasonable requirements. packing densities between a few % and up to 20%, have been made of various materi- Brushes with gold, platinum, niobium als by the

Bidirectional Brush Seals: Post-Test Analysis

NASA Technical Reports Server (NTRS)

Hendricks, Robert C.; Wilson, Jack; Wu, Tom Y.; Flower, Ralph; Mullen, Robert L.

1997-01-01

A post-test analysis of a set of inside-diameter/outside-diameter (ID/OD) bidirectional brush seals used in three-port wave rotor tests was undertaken to determine brush bristle and configuration wear, pullout, and rotor coating wear. The results suggest that sharp changes in the pressure profiles were not well reflected in bristle tip configuration patterns or wear. Also, positive-to-negative changes in axial pressure gradients appeared to have little effect on the backing plates. Although the brushes had similar porosities, they had very different unpacked arrays. This difference could explain the departure of experimental data from computational fluid dynamics flow predictions for well-packed arrays at higher pressure drops. The rotor wear led to "car-track" scars (upper and lower wear bands) with a whipped surface between the bands. Those bands may have resulted from bristle stiffening at the fence and gap plates during alternate portions of the rotor cycle. Within the bristle response range the wear surface reflected the pressure distribution effect on bristle motion. No sacrificial metallurgical data were taken. The bristles did wear, with correspondingly more wear on the ID brush configurations than on the OD configurations; the complexity in constructing the ID brush was a factor.

Binary Polymer Brushes of Strongly Immiscible Polymers.

PubMed

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.

Tooth brushing habits in uninstructed adults--frequency, technique, duration and force.

PubMed

Ganss, C; Schlueter, N; Preiss, S; Klimek, J

2009-06-01

Professional recommendations for individual oral hygiene mostly include tooth brushing at least twice daily for 2-3 min with gentle force using the Bass technique or modifications of it. This study evaluated whether habitual tooth brushing actually meets these standards. Uninstructed adults (n = 103; mean age 31 +/- 6 years; 61 female, 42 male) with habitual manual tooth brushing were given a self-administered questionnaire about the frequency of brushing and a computer system recorded their brushing technique, duration and force. The majority (79.6%) of participants brushed twice daily. The mean brushing duration was 96.6 +/- 36.0 s, the mean brushing force was 2.3 +/- 0.7 N (max. 4.1 N), and no significant differences were found for quadrants. Most subjects (73.8%) brushed with circling, 8.7% with horizontal/scrubbing, 13.6% with horizontal/circling and 3.9% with vertical/sweeping movements. Modified Bass technique was not observed. When appropriate brushing habits were defined as brushing at least twice daily for 120 s with a brushing force of less than 3 N and with circling or vertical sweeping movements, only 25.2% of the participants fulfilled all criteria, emphasising the ongoing need for oral hygiene education.

Proper Brushing

MedlinePlus

... bristles along the gumline at a 45-degree angle. Bristles should contact both the tooth surface and the gumline. Gently ... A rolling motion is when the brush makes contact with the gumline and ... a 45-degree angle with bristles contacting the tooth surface and gumline. ...

Regulation of protein expression and function of octn2 in forskolin-induced syncytialization in BeWo Cells.

PubMed

Huang, F-D; Kung, F-L; Tseng, Y-C; Chen, M-R; Chan, H-S; Lin, C-J

2009-02-01

Placental OCTN2 is a high-affinity carnitine transporter that can interact with a number of therapeutic agents. The process of syncytialization is associated with the expression of a variety of genes. However, the association between syncytialization and OCTN2 expression is not yet clear. Given that forskolin induces BeWo cells to undergo biochemical and morphological differentiation, the purpose of the present study was to investigate whether the function and expression of OCTN2 are influenced by forskolin treatment during syncytialization. The forskolin-induced differentiation of BeWo cells was validated by secretion of beta-human chorionic gonadotropin (beta-hCG) and syncytin expression. Cellular localization of OCTN2 was analyzed by confocal microscopy. Expression of OCTN2 and the modular proteins PDZK1, PDZK2, NHERF1 and NHERF2 was analyzed by Western blotting and carnitine uptake by BeWo cells was estimated and the kinetic properties of uptake measured. The results showed that forskolin treatment increased beta-hCG secretion and syncytin expression, suggesting induction of syncytialization. Confocal images of BeWo cells showed the localization of OCTN2 in the brush-border membrane. OCTN2 protein expression was upregulated in isolated brush-border membranes by long-term forskolin treatment, but the V(m) for carnitine uptake was unchanged, although the K(m) increased. PDZK1, NHERF1 and NHERF2 protein expression in the brush-border membrane was downregulated by forskolin treatment, whereas PDZK2 levels remained unchanged. In conclusion, protein expression and function of OCTN2 in BeWo cells can be regulated by forskolin treatment. While the presence of forskolin results in an increase in OCTN2 protein expression, the increase in uptake capacity may be compensated by the decreased expression of PDZK1, NHERF1 or NHERF2.

Comparing solvophobic and multivalent induced collapse in polyelectrolyte brushes

DOE PAGES

Jackson, Nicholas E.; Brettmann, Blair K.; Vishwanath, Venkatram; ...

2017-02-03

Here, coarse-grained molecular dynamics enhanced by free-energy sampling methods is used to examine the roles of solvophobicity and multivalent salts on polyelectrolyte brush collapse. Specifically, we demonstrate that while ostensibly similar, solvophobic collapsed brushes and multivalent-ion collapsed brushes exhibit distinct mechanistic and structural features. Notably, multivalent-induced heterogeneous brush collapse is observed under good solvent polymer backbone conditions, demonstrating that the mechanism of multivalent collapse is not contingent upon a solvophobic backbone. Umbrella sampling of the potential of mean-force (PMF) between two individual brush strands confirms this analysis, revealing starkly different PMFs under solvophobic and multivalent conditions, suggesting the role ofmore » multivalent “bridging” as the discriminating feature in trivalent collapse. Structurally, multivalent ions show a propensity for nucleating order within collapsed brushes, whereas poor-solvent collapsed brushes are more disordered; this difference is traced to the existence of a metastable PMF minimum for poor solvent conditions, and a global PMF minimum for trivalent systems, under experimentally relevant conditions.« less

Comparing solvophobic and multivalent induced collapse in polyelectrolyte brushes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jackson, Nicholas E.; Brettmann, Blair K.; Vishwanath, Venkatram

Here, coarse-grained molecular dynamics enhanced by free-energy sampling methods is used to examine the roles of solvophobicity and multivalent salts on polyelectrolyte brush collapse. Specifically, we demonstrate that while ostensibly similar, solvophobic collapsed brushes and multivalent-ion collapsed brushes exhibit distinct mechanistic and structural features. Notably, multivalent-induced heterogeneous brush collapse is observed under good solvent polymer backbone conditions, demonstrating that the mechanism of multivalent collapse is not contingent upon a solvophobic backbone. Umbrella sampling of the potential of mean-force (PMF) between two individual brush strands confirms this analysis, revealing starkly different PMFs under solvophobic and multivalent conditions, suggesting the role ofmore » multivalent “bridging” as the discriminating feature in trivalent collapse. Structurally, multivalent ions show a propensity for nucleating order within collapsed brushes, whereas poor-solvent collapsed brushes are more disordered; this difference is traced to the existence of a metastable PMF minimum for poor solvent conditions, and a global PMF minimum for trivalent systems, under experimentally relevant conditions.« less

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

PubMed

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.

Localization of the action of cholera toxin on adenyl cyclase in mucosal epithelial cells of rabbit intestine

PubMed Central

Parkinson, David K.; Ebel, Hans; DiBona, Donald R.; Sharp, Geoffrey W. G.

1972-01-01

Brush borders and plasma membranes have been purified from mucosal epithelial cells of rabbit ileum under control conditions and after treatment for 3 hr with cholera toxin in vivo. The activity of several enzymes in these preparations was measured. It was concluded that adenyl cyclase, like NaK-ATPase, seems not to be a normal constituent of brush borders. Both these enzymes are present in plasma membrane preparations derived largely from the basal and lateral margins of the epithelial cells, both may be phospholipid dependent enzymes and both are affected by cholera toxin. Adenyl cyclase activity is increased while NaK-ATPase is decreased. The activities of alkaline phosphatase, leucineaminopeptidase, 5′-nucleotidase, glucose-6-phosphatase, and Mg-ATPase were not found to be affected by the toxin. Cholera toxin, which makes contact with the luminal side of the epithelial cells, in the natural disease and in the experimental model, would appear to exert its pathologic effect on adenyl cyclase at the opposite (basal and lateral) side of the cells. Images PMID:4344729

[Brushing abrasion of the enamel surface after erosion].

PubMed

Lipei, Chen; Xiangke, Ci; Xiaoyan, Ou

2017-08-01

Objective A study was conducted to compare the effect of different enamel remineralization periods after erosion on the depth of brushing abrasion. Methods Ten volunteers were selected for a 4-day experiment. A total of 60 enamels were randomly assigned into six groups (A-F) and placed in intraoral palatal devices. On the first day, the palatal devices were placed in oral cavity (24 h) . On the following three days, brushing experiments were performed extraorally, two times per day. The specific experimental method of brushing follows these next steps. First, the group F specimens were covered with a film of wax, and then acid etched for 2 min. Subsequently, the film of wax was detached. The groups from A to D were brushed after remineralization at the following time intervals: group A, 0 min; group B, 20 min; group C, 40 min; group D, 60 min. Erosion and remineralization were performed on group E, but without brushing. Remineralization was performed on group F, but without acid etching and brushing. The depth of enamel abrasion was determined by a mechanical profilometer. The surface morphology of the enamel blocks was observed using a scanning electron microscope. Results 1) The depth of abrasion was different in varied enamel remineralization time after acid etching. The statistical significant differences between groups were as follows. 2) When the time of enamel remineralization after acid etching was short, the surface depression in the electron microscope was deep, and the surface morphology was rough. Conclusion Brushing immediately after acid etching would cause much serious abrasion to the enamel surface. Brushing after 60 min can effectively reduce the abrasion of acid etching enamel.

Method for making a high current fiber brush collector

NASA Astrophysics Data System (ADS)

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.

Tribological properties of hydrophilic polymer brushes under wet conditions.

PubMed

Kobayashi, Motoyasu; Takahara, Atsushi

2010-08-01

This article demonstrates a water-lubrication system using high-density hydrophilic polymer brushes consisting of 2,3-dehydroxypropyl methacrylate (DHMA), vinyl alcohol, oligo(ethylene glycol)methyl ether methacrylate, 2-(methacryloyloxy)ethyltrimethylammonium chloride (MTAC), 3-sulfopropyl methacrylate potassium salt (SPMK), and 2-methacryloyloxyethyl phosphorylcholine (MPC) prepared by surface-initiated controlled radical polymerization. Macroscopic frictional properties of brush surfaces were characterized by sliding a glass ball probe in water using a ball-on-plate type tribotester under the load of 0.1-0.49 N at the sliding velocity of 10(-5)-10(-1) m s(-1) at 298 K. A poly(DHMA) brush showed a relatively larger friction coefficient in water, whereas the polyelectrolyte brushes, such as poly(SPMK) and poly(MPC), revealed significantly low friction coefficients below 0.02 in water and in humid air conditions. A drastic reduction in the friction coefficient of polyelectrolyte brushes in aqueous solution was observed at around 10(-3)-10(-2) m s(-1) owing to the hydrodynamic lubrication effect, however, an increase in salt concentration in the aqueous solution led to the increase in the friction coefficients of poly(MTAC) and poly(SPMK) brushes. The poly(SPMK) brush showed a stable and low friction coefficient in water even after sliding over 450 friction cycles, indicating a good wear resistance of the brush film. Copyright 2010 The Japan Chemical Journal Forum and Wiley Periodicals, Inc.

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

PubMed

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.

Structure of Polyelectrolyte Brushes in the Presence of Multivalent Counterions

DOE PAGES

Yu, Jing; Mao, Jun; Yuan, Guangcui; ...

2016-07-20

Polyelectrolyte brushes are of great importance to a wide range of fields, ranging from colloidal stabilization to responsive and tunable materials to lubrication. Here, we synthesized high-density polystyrenesulfonate (PSS) brushes using surface initiated atom transfer radical polymerization and performed neutron reflectivity (NR) and surface force measurements using a surface forces apparatus (SFA) to investigate the effect of monovalent Na +, divalent Ca 2+, Mg 2+, and Ba 2+, and trivalent Y 3+ counterions on the structure of the PSS brushes. NR and SFA results demonstrate that in monovalent salt solution the behavior of the PSS brushes agrees with scaling theorymore » well, exhibiting two distinct regimes: the osmotic and salted brush regimes. Introducing trivalent Y 3+ cations causes an abrupt shrinkage of the PSS brush due to the uptake of Y 3+ counterions. The uptake of Y 3+ counterions and shrinkage of the brush are reversible upon increasing the concentration of monovalent salt. Divalent cations, Mg 2+, Ca 2+, and Ba 2+, while all significantly affecting the structure of PSS brushes, show strong ion specific effects that are related to the specific interactions between the divalent cations and the sulfonate groups. Our results demonstrate that the presence of multivalent counterions, even at relatively low concentrations, can strongly affect the structure of polyelectrolyte brushes. Finally, the results also highlight the importance of ion specificity to the structure of polyelectrolyte brushes in solution.« less

Study on brush of moving electrode type electrostatic precipitator (MEEP)

NASA Astrophysics Data System (ADS)

Zhao, Haibao; He, Yuzhong; Yao, Yuping

2018-02-01

MEEP was an efficient particle removal technology for coal plant and sintering machine. As the stability of brush in MEEP was relatively poor, the experiments was designed for the brush which was made by 0Cr18Ni9 stainless steel wire to find the failure mode and cause. Combining the results of the experiments, the failure models of brushes were different under different conditions and the brushes were suitable for being used in the condition of small diameter particles. And the life span of brushes can be more than 6 years.

Identification of Escherichia coli F4ac-binding proteins in porcine milk fat globule membrane

PubMed Central

Novakovic, Predrag; Huang, Yanyun Y.; Lockerbie, Betty; Shahriar, Farshid; Kelly, John; Gordon, John R.; Middleton, Dorothy M.; Loewen, Matthew E.; Kidney, Beverly A.; Simko, Elemir

2015-01-01

F4ac-positive enterotoxigenic Escherichia coli (ETEC) must attach to the intestinal mucosa to cause diarrhea in piglets. Prevention of bacterial attachment to the intestinal mucosa is the most effective defense against ETEC-induced diarrhea. Porcine milk fat globule membranes (MFGM) were shown to be able to inhibit attachment of ETEC to the intestinal brush border; however, the specific components of porcine MFGM that inhibited attachment of ETEC to enterocytes were not identified. Accordingly, the purpose of this study was to identify F4ac-binding MFGM proteins by overlay Western blot and affinity chromatography. The proteome of porcine MFGM was characterized and the following F4ac-binding proteins were detected by overlay Western blot and affinity chromatography: lactadherin, butyrophilin, adipophilin, acyl-CoA synthetase 3, and fatty acid-binding protein 3. The biological function of these proteins was not investigated but it is possible that their interaction with F4ac fimbria interferes with bacterial attachment and colonization. PMID:25852227

Role of human placental apical membrane transporters in the efflux of glyburide, rosiglitazone, and metformin

PubMed Central

HEMAUER, Sarah J.; PATRIKEEVA, Svetlana L.; NANOVSKAYA, Tatiana N.; HANKINS, Gary D.V.; AHMED, Mahmoud S.

2010-01-01

Objective Substrates of placental efflux transporters could compete for a single transporter, which could result in an increase in the transfer of each substrate to the fetal circulation. Our aim was to determine the role of placental transporters in the biodisposition of oral hypoglycemic drugs that could be used as monotherapy or in combination therapy for gestational diabetes. Study design Inside-out brush border membrane vesicles from term placentas were used to determine the efflux of glyburide, rosiglitazone, and metformin by P-gp, Breast Cancer Resistance Protein (BCRP), and Multidrug Resistance Protein (MRP1). Results Glyburide was transported by MRP1 (43 ± 4%); BCRP (25 ± 5%); and P-gp (9 ± 5%). Rosiglitazone was transported predominantly by P-gp (71 ± 26%). Metformin was transported by P-gp (58 ± 20%) and BCRP (25 ± 14%). Conclusion Multiple placental transporters contribute to efflux of glyburide, rosiglitazone, and metformin. Administration of drug combinations could lead to their competition for efflux transporters. PMID:20350646

A Brush Seals Program Modeling and Developments

NASA Technical Reports Server (NTRS)

Hendricks, Robert C.; Flower, Ralph; Howe, Harold

1996-01-01

Some events of a U.S. Army/NASA Lewis Research Center brush seals program are reviewed, and the development of ceramic brush seals is described. Some preliminary room-temperature flow data are modeled and compare favorably to the results of Ergun.

Role of Sphingolipids in Infant Gut Health and Immunity.

PubMed

Nilsson, Åke

2016-06-01

Sphingomyelin (SM), glycosphingolipids, and gangliosides are important polar lipids in the milk fat globule membrane but are not found in standard milk replacement formulas. Because digestion and absorption of SM and glycosphingolipids generate the bioactive metabolites ceramide, sphingosine, and sphingosine-1-phosphate (S1P), and because intact gangliosides may have beneficial effects in the gut, this may be important for gut integrity and immune maturation in the neonate. The brush border enzymes that hydrolyze milk SM, alkaline sphingomyelinase (nucleotide phosphodiesterase pyrophosphatase 7), and neutral ceramidase are expressed at birth in both term and preterm infants. Released sphingosine is absorbed, phosphorylated to S1P, and converted to palmitic acid via S1P-lyase in the gut mucosa. Hypothetically, S1P also may be released from absorptive cells and exert important paracrine actions favoring epithelial integrity and renewal, as well as immune function, including secretory IgA production and migration of T lymphocyte subpopulations. Gluco-, galacto-, and lactosylceramide are hydrolyzed to ceramide by lactase-phlorizin hydrolase, which also hydrolyzes lactose. Gangliosides may adhere to the brush border and is internalized, modified, and possibly transported into blood, and may exert protective functions by their interactions with bacteria, bacterial toxins, and the brush border. Copyright © 2016 Elsevier Inc. All rights reserved.

75 FR 21347 - Natural Bristle Paint Brushes From China

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-23

... Brushes From China AGENCY: United States International Trade Commission. ACTION: Scheduling of a full five-year review concerning the antidumping duty order on natural bristle paint brushes from China. SUMMARY... antidumping duty order on natural bristle paint brushes from China would be likely to lead to continuation or...

Synthesis and Biomedical Applications of Poly((meth)acrylic acid) Brushes.

PubMed

Qu, Zhenyuan; Xu, Hong; Gu, Hongchen

2015-07-15

Poly((meth)acrylic acid) (P(M)AA) brushes possess a number of distinctive properties that are particularly attractive for biomedical applications. This minireview summarizes recent advances in the synthesis and biomedical applications of P(M)AA brushes and brushes containing P(M)AA segments. First, we review different surface-initiated polymerization (SIP) methods, with a focus on recent progress in the surface-initiated controlled/living radical polymerization (SI-CLRP) techniques used to generate P(M)AA brushes with a tailored structure. Next, we discuss biomolecule immobilization methods for P(M)AA brushes, including physical adsorption, covalent binding, and affinity interactions. Finally, typical biomedical applications of P(M)AA brushes are reviewed, and their performance is discussed based on their unique properties. We conclude that P(M)AA brushes are promising biomaterials, and more potential biomedical applications are expected to emerge with the further development of synthetic techniques and increased understanding of their interactions with biological systems.

Lateral Structure Formation in Polyelectrolyte Brushes Induced by Multivalent Ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brettmann, Blair; Pincus, Philip; Tirrell, Matthew

2017-01-13

We provide a theoretical model for the collapse of polyelectrolyte brushes in the presence of multivalent ions, focusing on the formation of lateral inhomogeneties in the collapsed state. Polyelectrolyte brushes are important in a variety of applications, including stabilizing colloidal particles and lubricating surfaces. Many uses rely on the extension of the densely grafted polymer chains from the surface in the extended brush morphology. In the presence Extended Brush of multivalent ions, brushes are significantly shorter than in monovalent ionic solutions, which greatly affects their properties. We base our theoretical analysis on an analogous collapse of polyelectrolyte brushes in amore » poor solvent, providing an energy balance representation for pinned micelles and cylindrical bundles. The equilibrium brush heights predicted for these structures are of a similar magnitude to those measured experimentally. The formation of lateral structures can open new avenues for stimuli-responsive applications that rely on nanoscale pattern formation on surfaces.« less

The border-to-border distribution method for analysis of cytoplasmic particles and organelles.

PubMed

Yacovone, Shalane K; Ornelles, David A; Lyles, Douglas S

2016-02-01

Comparing the distribution of cytoplasmic particles and organelles between different experimental conditions can be challenging due to the heterogeneous nature of cell morphologies. The border-to-border distribution method was created to enable the quantitative analysis of fluorescently labeled cytoplasmic particles and organelles of multiple cells from images obtained by confocal microscopy. The method consists of four steps: (1) imaging of fluorescently labeled cells, (2) division of the image of the cytoplasm into radial segments, (3) selection of segments of interest, and (4) population analysis of fluorescence intensities at the pixel level either as a function of distance along the selected radial segments or as a function of angle around an annulus. The method was validated using the well-characterized effect of brefeldin A (BFA) on the distribution of the vesicular stomatitis virus G protein, in which intensely labeled Golgi membranes are redistributed within the cytoplasm. Surprisingly, in untreated cells, the distribution of fluorescence in Golgi membrane-containing radial segments was similar to the distribution of fluorescence in other G protein-containing segments, indicating that the presence of Golgi membranes did not shift the distribution of G protein towards the nucleus compared to the distribution of G protein in other regions of the cell. Treatment with BFA caused only a slight shift in the distribution of the brightest G protein-containing segments which had a distribution similar to that in untreated cells. Instead, the major effect of BFA was to alter the annular distribution of G protein in the perinuclear region.

Computer Simulations of Bottle Brushes: From Melts to Soft Networks

DOE PAGES

Cao, Zhen; Carrillo, Jan-Michael Y.; Sheiko, Sergei S.; ...

2015-07-13

We use a combination of Molecular dynamics simulations and analytical calculations, and study dens bottle-brush systems in a melt and network State. Analysis of our simulation results shows that bottle-brush macromolecules in melt behave as ideal chains with effective Kuhn length b K. Simulations show that the bottle-brush-induced bending rigidity is due to an entropy decrease caused by redistribution of the side chains upon backbone bending. The Kuhn length of the bottle:brushes increases with increasing the side-chain degree of polymerization n sc as b K proportional to n sc 0.46. Moreover, this model of bottle brush macromolecules is extended tomore » describe mechanical properties of bottle brush networks in linear and nonlinear deformation regimes. In the linear deformation regime, the network shear modulus scales with the degree of polymerization of the side chains as G 0 proportional to (n sc + 1) -1 as long as the ratio of the Kuhn length, b K, to the size of the fully extended bottle-brush backbone between cross-links, R-max, is smaller than unity, b K/R max << 1. Bottle-brush networks With b K/R max proportional to 1 demonstrate behavior similar to that of networks Of semiflexible chains with G 0 proportional to n sc -0.5. Finally, in the nonlinear network deformation regime, the deformation-dependent shear modulus is a universal function of the first strain invariant I 1 and bottle-brush backbone deformation ratio beta describing stretching ability of the bottle-brush backbone between cross-links.« less

[Clinical relevance of tooth brushing in relation to dental caries].

PubMed

Pita-Fernández, Salvador; Pombo-Sánchez, Antonio; Suárez-Quintanilla, Juan; Novio-Mallón, Silvia; Rivas-Mundiña, Berta; Pértega-Díaz, Sonia

2010-07-01

To determine the impact and clinical relevance of tooth brushing on oral health. Prevalence study. Fontiñas Health Centre. (Santiago de Compostela, Spain). Prevalence study (n=281 children aged 5-14 years. Odontological examination according to WHO methodology, to determine the frequency of tooth brushing, frequency of sweet consumption and their impact on the prevalence of caries. Logistic regression and estimation of the relative prevalence difference (RPD) and the Number Needed to Treat in order to prevent one additional bad outcome (NNT). The children who never brush their teeth have a 40% (95% CI: 24.3%-57.8%) of early caries, while those who brush their teeth several times a day have 15.3% (95% CI: 9.4%-23.7%). An association between not brushing the teeth and caries in primary teeth (OR=2.3; 95% CI:1.05-5.3) was observed after adjusting for age, sweet consumption and visits to the dentist. The same occurred with final teeth (OR=3.9; 95% CI:1.4-10.3). The RPD was 62%(95% CI: 30%-79%), meaning that prevalence of caries is 62% lower in children who brush their teeth several times a day as compared to those who never brush their teeth. The NNT is 4 (95% CI: 2.4-14), so for every 4 children who brush their teeth several times a day, there is one less case of caries, compared to those who never brush their teeth. There is a dose-response relationship between prevalence of caries and brushing frequency. The same effect was observed with definitive caries: RPD=55% (95% CI:16%-76%), NNT=5 (95% CI:2.8-53.3). Tooth brushing is related to oral health, with a major clinical impact. The positive effect of tooth brushing was superior to that of a correct diet. 2009 Elsevier España, S.L. All rights reserved.

Quantitative evaluation of toothbrush and arm-joint motion during tooth brushing.

PubMed

Inada, Emi; Saitoh, Issei; Yu, Yong; Tomiyama, Daisuke; Murakami, Daisuke; Takemoto, Yoshihiko; Morizono, Ken; Iwasaki, Tomonori; Iwase, Yoko; Yamasaki, Youichi

2015-07-01

It is very difficult for dental professionals to objectively assess tooth brushing skill of patients, because an obvious index to assess the brushing motion of patients has not been established. The purpose of this study was to quantitatively evaluate toothbrush and arm-joint motion during tooth brushing. Tooth brushing motion, performed by dental hygienists for 15 s, was captured using a motion-capture system that continuously calculates the three-dimensional coordinates of object's motion relative to the floor. The dental hygienists performed the tooth brushing on the buccal and palatal sides of their right and left upper molars. The frequencies and power spectra of toothbrush motion and joint angles of the shoulder, elbow, and wrist were calculated and analyzed statistically. The frequency of toothbrush motion was higher on the left side (both buccal and palatal areas) than on the right side. There were no significant differences among joint angle frequencies within each brushing area. The inter- and intra-individual variations of the power spectrum of the elbow flexion angle when brushing were smaller than for any of the other angles. This study quantitatively confirmed that dental hygienists have individual distinctive rhythms during tooth brushing. All arm joints moved synchronously during brushing, and tooth brushing motion was controlled by coordinated movement of the joints. The elbow generated an individual's frequency through a stabilizing movement. The shoulder and wrist control the hand motion, and the elbow generates the cyclic rhythm during tooth brushing.

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

PubMed

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.

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

PubMed

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.

Evaluation of Internal Brushing on Pinch Weld Quality

DOE Office of Scientific and Technical Information (OSTI.GOV)

Korinko, P

2005-12-01

Post machining operations such as borescope inspection can cause linear indications down the length of the bore of fill stems. Often these indications are removed or obscured using rotary wire brushing. This study evaluated the effect this mechanical operation may have on pinch weld quality when relatively cold welds were made. A total of four stems with two levels of brushing of both Type 304L and 21-6-9 stainless steels were tested. In addition, two each of the Type 304L stems were Nitradd cleaned and the other two were aqueously cleaned; all four 21-6-9 stems were aqueously cleaned. All of themore » brushed stem areas exhibited more surface anomalies based on borescope evaluation. On average, the bond rating was a higher value (worse) for the brushed areas than the unadulterated areas for both Type 304L and 21-6-9 stems. The test method used may have biased the results towards a lesser quality bond for the brushed areas so additional testing is recommended.« less

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

PubMed

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.

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

NASA Astrophysics Data System (ADS)

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.

Self-Assembling Brush Polymers Bearing Multisaccharides.

PubMed

Lee, Jongchan; Kim, Jin Chul; Lee, Hoyeol; Song, Sungjin; Kim, Heesoo; Ree, Moonhor

2017-06-01

Three different series of brush polymers bearing glucosyl, maltosyl, or maltotriosyl moiety at the bristle end are successfully prepared by using cationic ring-opening polymerization and two sequential postmodification reactions. All brush polymers, except for the polymer containing 100 mol% maltotriosyl moiety, demonstrate the formation of multibilayer structure in films, always providing saccharide-enriched surface. These self-assembling features are remarkable, regarding the bulkiness of saccharide moieties and the kink in the bristle due to the triazole linker. The saccharide-enriched film surfaces reveal exceptionally high specific binding affinity to concanavalin A but suppress nonspecific binding of plasma proteins severely. Overall, the brush polymers bearing saccharide moieties of various kinds in this study are highly suitable materials for biomedical applications including biosensors. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Mueller matrix model of Haidinger's brushes.

PubMed

Misson, Gary P

2003-09-01

Stokes vectors and Mueller matrices are used to model the polarisation properties (birefringence, dichroism and depolarisation) of any optical system, in particular the human eye. An explanation of the form and behaviour of the entoptic phenomenon of Haidinger's brushes is derived that complements and expands upon a previous study. The relationship between the appearance of Haidinger's brushes and intrinsic ocular retardation is quantified and the model allows prediction of the effect of any retarder of any orientation placed between a source of polarised light and the eye. The simple relationship of minimum contrast of Haidinger's brushes to the cosine of total retardation is derived.

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

PubMed Central

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

Ceramic brush seals development

NASA Technical Reports Server (NTRS)

Howe, Harold

1994-01-01

The following topics are discussed in this viewgraph presentation: ceramic brush seals, research and development, manufacturing, brazed assembly development, controlling braze flow, fiber selection, and braze results.

From Comb-like Polymers to Bottle-Brushes

NASA Astrophysics Data System (ADS)

Liang, Heyi; Cao, Zhen; Dobrynin, Andrey; Sheiko, Sergei

We use a combination of the coarse-grained molecular dynamics simulations and scaling analysis to study conformations of bottle-brushes and comb-like polymers in a melt. Our analysis show that bottle-brushes and comb-like polymers can be in four different conformation regimes depending on the number of monomers between grafted side chains and side chain degree of polymerization. In loosely-grafted comb regime (LC) the degree of polymerization between side chains is longer than side chain degree of polymerization, such that the side chains belonging to the same macromolecule do not overlap. Crossover to a new densely-grafted comb regime (DC) takes place when side chains begin to overlap reducing interpenetration of side chains belonging to different macromolecules. In these two regimes both side-chains and backbone behave as unperturbed linear chains with the effective Kuhn length of the backbone being close to that of linear chain. Further decrease spacer degree of polymerization results in crossover to loosely-grafted bottle-brush regime (LB). In this regime, the bottle-brush backbone is stretched while the side-chains still maintain ideal chain conformation. Finally, for even shorter spacer between grafted side chains, which corresponds to densely-grafted bottle-brush regime (DB), the backbone adopts a fully extended chain conformation, and side-chains begin to stretch to maintain a constant monomer density. NSF DMR-1409710, DMR-1407645, DMR-1624569, DMR-1436201.

Tension amplification in tethered layers of bottle-brush polymers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leuty, Gary M.; Tsige, Mesfin; Grest, Gary S.

2016-02-26

In this paper, molecular dynamics simulations of a coarse-grained bead–spring model have been used to study the effects of molecular crowding on the accumulation of tension in the backbone of bottle-brush polymers tethered to a flat substrate. The number of bottle-brushes per unit surface area, Σ, as well as the lengths of the bottle-brush backbones N bb (50 ≤ N bb ≤ 200) and side chains N sc (50 ≤ N sc ≤ 200) were varied to determine how the dimensions and degree of crowding of bottle-brushes give rise to bond tension amplification along the backbone, especially near the substrate.more » From these simulations, we have identified three separate regimes of tension. For low Σ, the tension is due solely to intramolecular interactions and is dominated by the side chain repulsion that governs the lateral brush dimensions. With increasing Σ, the interactions between bottle-brush polymers induce compression of the side chains, transmitting increasing tension to the backbone. For large Σ, intermolecular side chain repulsion increases, forcing side chain extension and reorientation in the direction normal to the surface and transmitting considerable tension to the backbone.« less

Importance of filament diameter when using bass brushing technique.

PubMed

Vowles, A D; Wade, A B

1977-08-01

A comparative study using a crossover experimental construction was made of the effectiveness of brushes containing 6/10 nylon filaments of 0.132 mm mean diameter using a Bass technique with those containing filaments of the same type of nylon but 0.280 mm diameter. Each type of brush was used for a 2-week period. Even though the finer filament brushes contained more than three times as many filaments, they were inferior in cleaning achievement to the brushes with the broader filaments. The difference was particularly marked on the facial aspect, but was largely nullified lingually. The effectiveness of the Bass technique in the gingival zone demonstrated in a previous investigation when brushes containing filaments of 0.18 and 0.20 mm were used, was not found in this investigation. It is concluded that filament diameter is critical in achieving effective cleaning using the Bass technique.

Modulation of ileal bile acid transporter (ASBT) activity by depletion of plasma membrane cholesterol: association with lipid rafts

PubMed Central

Annaba, Fadi; Sarwar, Zaheer; Kumar, Pradeep; Saksena, Seema; Turner, Jerrold R.; Dudeja, Pradeep K.; Gill, Ravinder K.; Alrefai, Waddah A.

2016-01-01

Apical sodium-dependent bile acid transporter (ASBT) represents a highly efficient conservation mechanism of bile acids via mediation of their active transport across the luminal membrane of terminal ileum. To gain insight into the cellular regulation of ASBT, we investigated the association of ASBT with cholesterol and sphingolipid-enriched specialized plasma membrane microdomains known as lipid rafts and examined the role of membrane cholesterol in maintaining ASBT function. Human embryonic kidney (HEK)-293 cells stably transfected with human ASBT, human ileal brush-border membrane vesicles, and human intestinal epithelial Caco-2 cells were utilized for these studies. Floatation experiments on Optiprep density gradients demonstrated the association of ASBT protein with lipid rafts. Disruption of lipid rafts by depletion of membrane cholesterol with methyl-β-cyclodextrin (MβCD) significantly reduced the association of ASBT with lipid rafts, which was paralleled by a decrease in ASBT activity in Caco-2 and HEK-293 cells treated with MβCD. The inhibition in ASBT activity by MβCD was blocked in the cells treated with MβCD-cholesterol complexes. Kinetic analysis revealed that MβCD treatment decreased the Vmax of the transporter, which was not associated with alteration in the plasma membrane expression of ASBT. Our study illustrates that cholesterol content of lipid rafts is essential for the optimal activity of ASBT and support the association of ASBT with lipid rafts. These findings suggest a novel mechanism by which ASBT activity may be rapidly modulated by alterations in cholesterol content of plasma membrane and thus have important implications in processes related to maintenance of bile acid and cholesterol homeostasis. PMID:18063707

CALCIUM TRANSPORT PROCESSES OF LOBSTER HEPATOPANCREATIC BRUSH BORDER MEMBRANE VESICLES. (R823068)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

A switchable polymer layer: Chain folding in end-charged polymer brushes

NASA Astrophysics Data System (ADS)

Heine, David; Wu, David T.

2001-03-01

We use a self-consistent field approximation to model the configurations of end-charged homopolymer and block copolymer brushes in response to an external electric field due to charges on the grafting surface. By varying the charge density on the grafting surface, we can cause the chains either to extend outward, greatly increasing the brush height, or to loop back to the grafting surface. We show that such a copolymer brush can present one block at the exposed surface in the extended state and present the other block in the retracted state. This occurs for both a solvated brush and a dry brush. We also compare these results to those of a modified Alexander-de Gennes model for the end-charged homopolymer brush.

Cloning strategy for producing brush-forming protein-based polymers.

PubMed

Henderson, Douglas B; Davis, Richey M; Ducker, William A; Van Cott, Kevin E

2005-01-01

Brush-forming polymers are being used in a variety of applications, and by using recombinant DNA technology, there exists the potential to produce protein-based polymers that incorporate unique structures and functions in these brush layers. Despite this potential, production of protein-based brush-forming polymers is not routinely performed. For the design and production of new protein-based polymers with optimal brush-forming properties, it would be desirable to have a cloning strategy that allows an iterative approach wherein the protein based-polymer product can be produced and evaluated, and then if necessary, it can be sequentially modified in a controlled manner to obtain optimal surface density and brush extension. In this work, we report on the development of a cloning strategy intended for the production of protein-based brush-forming polymers. This strategy is based on the assembly of modules of DNA that encode for blocks of protein-based polymers into a commercially available expression vector; there is no need for custom-modified vectors and no need for intermediate cloning vectors. Additionally, because the design of new protein-based biopolymers can be an iterative process, our method enables sequential modification of a protein-based polymer product. With at least 21 bacterial expression vectors and 11 yeast expression vectors compatible with this strategy, there are a number of options available for production of protein-based polymers. It is our intent that this strategy will aid in advancing the production of protein-based brush-forming polymers.

Polymer Brushes: Synthesis, Characterization, Applications

NASA Astrophysics Data System (ADS)

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".

Attraction between Opposing Planar Dipolar Polymer Brushes

DOE PAGES

Mahalik, J. P.; Sumpter, Bobby G.; Kumar, Rajeev

2017-08-01

In this paper, we use a field theory approach to study the effects of permanent dipoles on interpenetration and free energy changes as a function of distance between two identical planar polymer brushes. Melts (i.e., solvent-free) and solvated brushes made up of polymers grafted on nonadsorbing substrates are studied. In particular, the weak coupling limit of the dipolar interactions is considered, which leads to concentration-dependent pairwise interactions, and the effects of orientational order are neglected. It is predicted that a gradual increase in the dipole moment of the polymer segments can lead to attractive interactions between the brushes at intermediatemore » separation distances. Finally, because classical theory of polymer brushes based on the strong stretching limit (SSL) and the standard self-consistent field theory (SCFT) simulations using the Flory’s χ parameter always predicts repulsive interactions at all separations, our work highlights the importance of dipolar interactions in tailoring and accurately predicting forces between polar polymeric interfaces in contact with each other.« less

Tandem catalysis for the preparation of cylindrical polypeptide brushes.

PubMed

Rhodes, Allison J; Deming, Timothy J

2012-11-28

Here, we report a method for synthesis of cylindrical copolypeptide brushes via N-carboxyanhydride (NCA) polymerization utilizing a new tandem catalysis approach that allows preparation of brushes with controlled segment lengths in a straightforward, one-pot procedure requiring no intermediate isolation or purification steps. To obtain high-density brush copolypeptides, we used a "grafting from" approach where alloc-α-aminoamide groups were installed onto the side chains of NCAs to serve as masked initiators. These groups were inert during cobalt-initiated NCA polymerization and gave allyloxycarbonyl-α-aminoamide-substituted polypeptide main chains. The alloc-α-aminoamide groups were then activated in situ using nickel to generate initiators for growth of side-chain brush segments. This use of stepwise tandem cobalt and nickel catalysis was found to be an efficient method for preparation of high-chain-density, cylindrical copolypeptide brushes, where both the main chains and side chains can be prepared with controlled segment lengths.

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

Treesearch

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...

Nanotribology of charged polymer brushes

NASA Astrophysics Data System (ADS)

Klein, Jacob

Polymers at surfaces, whose modern understanding may be traced back to early work by Sam Edwards1, have become a paradigm for modification of surface properties, both as steric stabilizers and as remarkable boundary lubricants2. Charged polymer brushes are of particular interest, with both technological implications and especially biological relevance where most macromolecules are charged. In the context of biolubrication, relevant in areas from dry eye syndrome to osteoarthritis, charged polymer surface phases and their complexes with other macromolecules may play a central role. The hydration lubrication paradigm, where tenaciously-held yet fluid hydration shells surrounding ions or zwitterions serve as highly-efficient friction-reducing elements, has been invoked to understand the excellent lubrication provided both by ionized3 and by zwitterionic4 brushes. In this talk we describe recent advances in our understanding of the nanotribology of such charged brush systems. We consider interactions between charged end-grafted polymers, and how one may disentangle the steric from the electrostatic surface forces5. We examine the limits of lubrication by ionized brushes, both synthetic and of biological origins, and how highly-hydrated zwitterionic chains may provide extremely effective boundary lubrication6. Finally we describe how the lubrication of articular cartilage in the major joints, a tribosystem presenting some of the greatest challenges and opportunities, may be understood in terms of a supramolecular synergy between charged surface-attached polymers and zwitterionic groups7. Work supported by European Research Council (HydrationLube), Israel Science Foundation (ISF), Petroleum Research Fund of the American Chemical Society, ISF-NSF China Joint Program.

The effect of amino acids and dipeptides on sodium-ion transport in rat enterocytes.

PubMed

Cheeseman, C I; Devlin, D

1985-02-14

Sodium efflux from isolated intestinal epithelial cells was measured during incubation with several different free amino acids and dipeptides. L-Leucine, which is cotransported with sodium across the brush border membrane, significantly stimulated the total sodium efflux and almost all of this increase involved the ouabain-sensitive flux, i.e., the active component. In contrast, glycyl-L-leucine had little or no effect on active sodium efflux either in the presence or absence of 0.1 mM bestatin, a peptide hydrolase inhibitor. A second dipeptide L-carnosine (beta-alanyl-L-histidine) which is poorly hydrolysed by enterocytes also had no effect upon sodium efflux. However, glycylglycine, which has been shown to be cotransported with sodium, did stimulate the ionic efflux. In addition, measurement of sodium uptake by sheets of small intestine showed that glycyl-L-leucine, carnosine and glycyl-L-proline failed to increase the uptake of the ion, while glycylglycine did significantly stimulate sodium uptake. These data indicate that some dipeptides are not cotransported with sodium, while others are. This suggests that there may well be multiple peptide transporters with very different characteristics in the brush border membrane of enterocytes.

A Laterally-Mobile Mixed Polymer/Polyelectrolyte Brush Undergoes a Macroscopic Phase Separation

NASA Astrophysics Data System (ADS)

Lee, Hoyoung; Park, Hae-Woong; Tsouris, Vasilios; Choi, Je; Mustafa, Rafid; Lim, Yunho; Meron, Mati; Lin, Binhua; Won, You-Yeon

2013-03-01

We studied mixed PEO and PDMAEMA brushes. The question we attempted to answer was: When the chain grafting points are laterally mobile, how will this lateral mobility influence the structure and phase behavior of the mixed brush? Two different model mixed PEO/PDMAEMA brush systems were prepared: a mobile mixed brush by spreading a mixture of two diblock copolymers, PEO-PnBA and PDMAEMA-PnBA, onto the air-water interface, and an inseparable mixed brush using a PEO-PnBA-PDMAEMA triblock copolymer having respective brush molecular weights matched to those of the diblock copolymers. These two systems were investigated by surface pressure-area isotherm, X-ray reflectivity and AFM imaging measurements. The results suggest that the mobile mixed brush undergoes a lateral macroscopic phase separation at high chain grafting densities, whereas the inseparable system is only microscopically phase separated under comparable brush density conditions. We also conducted an SCF analysis of the phase behavior of the mixed brush system. This analysis further supported the experimental findings. The macroscopic phase separation observed in the mobile system is in contrast to the microphase separation behavior commonly observed in two-dimensional laterally-mobile small molecule mixtures.

Fundamental and Applied Studies of Polymer Membranes

NASA Astrophysics Data System (ADS)

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

Polyelectrolyte brushes in mixed ionic medium studied via intermolecular forces

NASA Astrophysics Data System (ADS)

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).

Membrane peptidases in the pig choroid plexus and on other cell surfaces in contact with the cerebrospinal fluid.

PubMed Central

Bourne, A; Barnes, K; Taylor, B A; Turner, A J; Kenny, A J

1989-01-01

A comprehensive survey of 11 peptidases, all of which are markers for renal microvillar membranes, has been made in membrane fractions prepared from pig choroid plexus. Two fractionation schemes were explored, both depending on a MgCl2-precipitation step, the preferred one having advantages in speed and yield of the activities. The specific activities of the peptidases in the choroid-plexus membranes were, with the exception of carboxypeptidase M, lower than in renal microvillar membranes: those of aminopeptidase N, peptidyl dipeptidase A ('angiotensin-converting enzyme') and gamma-glutamyltransferase were 3-5-fold lower, those of aminopeptidase A and endopeptidase-24.11 were 12-15 fold lower, and those of dipeptidyl peptidase IV and aminopeptidase W were 50-70-fold lower. Carboxypeptidase M had a similar activity in both membranes. Alkaline phosphatase and (Na+ + K+)-activated ATPase were more active in the choroid-plexus membranes. No activity for microsomal dipeptidase, aminopeptidase P and carboxypeptidase P could be detected. Six of the peptidases and (Na+ + K+)-activated ATPase were also studied by immunoperoxidase histochemistry at light- and electron-microscopic levels. Endopeptidase-24.11 and (Na+ + K+)-activated ATPase were uniquely located on the brush border, and the other two peptidases appeared to be much more abundant on the endothelial lining of microvessels. Dipeptidyl peptidase IV and aminopeptidase W were also detected in microvasculature. Pial membranes associated with the brain and spinal cord also stained positively for endopeptidase-24.11, aminopeptidase N and peptidyl dipeptidase A. The immunohistochemical studies indicated the subcellular fractionation did not discriminate between membranes derived from epithelial cells (i.e. microvilli) and those from endothelial cells. The possible significance of these studies in relation to neuropeptide metabolism and the control of cerebrospinal fluid production is discussed. Images Fig. 1. Fig. 2. Fig

Brushing force of manual and sonic toothbrushes affects dental hard tissue abrasion.

PubMed

Wiegand, Annette; Burkhard, John Patrik Matthias; Eggmann, Florin; Attin, Thomas

2013-04-01

This study aimed to determine the brushing forces applied during in vivo toothbrushing with manual and sonic toothbrushes and to analyse the effect of these brushing forces on abrasion of sound and eroded enamel and dentin in vitro. Brushing forces of a manual and two sonic toothbrushes (low and high frequency mode) were measured in 27 adults before and after instruction of the respective brushing technique and statistically analysed by repeated measures analysis of variance (ANOVA). In the in vitro experiment, sound and eroded enamel and dentin specimens (each subgroup n = 12) were brushed in an automatic brushing machine with the respective brushing forces using a fluoridated toothpaste slurry. Abrasion was determined by profilometry and statistically analysed by one-way ANOVA. Average brushing force of the manual toothbrush (1.6 ± 0.3 N) was significantly higher than for the sonic toothbrushes (0.9 ± 0.2 N), which were not significantly different from each other. Brushing force prior and after instruction of the brushing technique was not significantly different. The manual toothbrush caused highest abrasion of sound and eroded dentin, but lowest on sound enamel. No significant differences were detected on eroded enamel. Brushing forces of manual and sonic toothbrushes are different and affect their abrasive capacity. Patients with severe tooth wear and exposed and/or eroded dentin surfaces should use sonic toothbrushes to reduce abrasion, while patients without tooth wear or with erosive lesions confining only to enamel do not benefit from sonic toothbrushes with regard to abrasion.

Effective teaching of tooth-brushing to preschool children.

PubMed

Makuch, Almut; Reschke, Konrad; Rupf, Stefan

2011-01-01

The purpose of the present study was to compare artificial tooth-brushing models (TBM) and individual modeling regarding their efficacy in teaching the correct brushing movements to younger preschool children. A total of 141 30- to 50-month-old preschool children who had not been previously instructed on tooth-brushing were enrolled in the present trial. Four different model types/groups were compared: (1) giant TBM; (2) animal TBM puppet; (3) child him/herself in front of the mirror; (4) another person with the child in the mirror. Parameters of imitational learning were investigated by means of single-person monitoring on the basis of a standardized observational method. The subjects were randomly assigned to 4 experimental groups, which were comparable regarding gender and age. Statistical analysis was performed using the chi-square test. This study demonstrated that behavioral modeling types 3 and 4 were more suitable as a methodological basis than TBM. Correct tooth-brushing position and movement were correlated with the attractiveness of the model and its similarity to the child. It was shown that human models achieved greatest learning success. It is important to find a "helper" and an attractive model person assisting in guiding the brush with a feedback in a mirror.

Brushing Your Child's Teeth

MedlinePlus

... gov/ency/patientinstructions/000769.htm Brushing Your Child's Teeth To use the sharing features on this page, ... age. Taking care of your child's gums and teeth every day helps prevent tooth decay and gum ...

Wildlife responses to brush management: a contemporary evaluation

USDA-ARS?s Scientific Manuscript database

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...

[Effect of a tooth-brushing education program on oral health of preschool children].

PubMed

Kang, Bok-Hee; Park, Sun-Nam; Sohng, Kyeong-Yae; Moon, Jung-Soon

2008-12-01

To examine the effect of tooth-brushing education on the oral health of preschoolers. A quasi-experimental design with a non-equivalent control group was used. Two kindergartens were selected and 39 preschoolers from one kindergarten were assigned to the experimental group with tooth-brushing education and 39 from the other kindergarten to the control group. The tooth-brushing education program included 1 session on oral health education, individual tooth-brushing instruction for 1 week and supervised tooth-brushing after lunch for 4 weeks. Oral health behavior including use of tooth paste, tooth-brushing time and method of tooth-brushing, plague, streptococcus mutans, lactobacillus and dental caries were measured before and after the education. Fisher's exact test, t-test and paired t-test with the Window SAS 9.1 program were used to analyze the data. A significant increase in the use of tooth paste, tooth-brushing time and the practice of correct tooth-brushing and a decrease in plague and development of dental caries were observed in the experimental group. This tooth-brushing education was partially effective in improving oral health of preschoolers.

Polymer brush coatings for DNA: fundamental polymer physics and nanofabrication applications

NASA Astrophysics Data System (ADS)

de Vries, Renko

Recombinant DNA technology allows for the production of precisely defined self-assembling protein-based polymers. So far, the major applications for such protein-based polymers have been self-assembling hydrogels and micellar structures with biomedical application. Inspired by minimal models for the self-ssembly of rod-shaped viruses such as the tobacco mosaic virus, I have developed protein-polymers that co-assemble with DNA into rod-shaped virus-like particles, and protein-polymers that provide brush coatings around single DNA molecules. In this presentation I will focus on the latter, showing that on the one hand brush coated DNA is a rich model system for exploring the physics of bottle-brush polymers, while on the other hand brush coatings of DNA can also play an important practical role in nanofabrication. A key problem in the physics of bottle-brush polymers that I will address is the scale-dependence of bottle-brush elasticity. For long-wavelength thermal deformations probed by AFM imaging I will demonstrate that there is significant stiffening due to the brush coating, while for short wavelength thermal deformations probed by force spectroscopy, we find that stiffening due to the brush coating disappears completely. DNA brush coatings can also play an important practical role in nanofabrication by acting as a compatibilizer between chemically different building blocks. I will explore the example of DNA origami in combination with gold nanoparticles: while Mg2+ ions and high concentrations of monovalent salts are crucial for the stability of DNA origami, such solution conditions are typically incompatible with the colloidal stability of gold nanoparticles.I will show how DNA brush coatings can dramatically enhance the yield of formation of isolated DNA-gold nanoparticle composite nanostructures.

Unique Tuft Test Facility Dramatically Reduces Brush Seal Development Costs

NASA Technical Reports Server (NTRS)

Fellenstein, James A.

1997-01-01

Brush seals have been incorporated in the latest turbine engines to reduce leakage and improve efficiency. However, the life of these seals is limited by wear. Studies have shown that optimal sealing characteristics for a brush seal occur before the interference fit between the brush and shaft is excessively worn. Research to develop improved tribopairs (brush and coating) with reduced wear and lower friction has been hindered by the lack of an accurate, low-cost, efficient test methodology. Estimated costs for evaluating a new material combination in an engine company seal test program are on the order of $100,000. To address this need, the NASA Lewis Research Center designed, built, and validated a unique, innovative brush seal tuft tester that slides a single tuft of brush seal wire against a rotating shaft under controlled loads, speeds, and temperatures comparable to those in turbine engines. As an initial screening tool, the brush seal tuft tester can tribologicaly evaluate candidate seal materials for 1/10th the cost of full-scale seal tests. Previous to the development of the brush seal tuft tester facility, most relevant tribological data had been obtained from full-scale seal tests conducted primarily to determine seal leakage characteristics. However, from a tribological point of view, these tests included the confounding effects of varying contact pressures, bristle flaring, high-temperature oxidation, and varying bristle contact angles. These confounding effects are overcome in tuft testing. The interface contact pressures can be either constant or varying depending on the tuft mounting device, and bristle wear can be measured optically with inscribed witness marks. In a recent cooperative program with a U.S. turbine engine manufacturer, five metallic wire candidates were tested against a plasma-sprayed Nichrome-bonded chrome carbide. The wire materials used during this collaboration were either nickel-chrome- or cobaltchrome-based superalloys. These

Impact of brushing force on abrasion of acid-softened and sound enamel.

PubMed

Wiegand, A; Köwing, L; Attin, T

2007-11-01

The study aimed to analyse the effects of different brushing loads on abrasion of acid-softened and sound enamel surfaces. Sound and acid-softened surfaces of each 10 human enamel samples were submitted to brushing abrasion in an automatic brushing machine at 1.5 N (A), 2.5 N (B), 3.5 N (C) or 4.5 N (D) brushing load. Prior to abrasion, demineralisation of half of each enamel surface was performed by storage in hydrochloric acid (pH 2.0) for 60s. Brushing was carried out (1000 strokes) using a manual toothbrush and toothpaste slurry in a ratio of 1:3. Enamel loss was measured after 10, 20, 50, 100, 150, 200, 250, 300, 350 and 1000 brushing strokes (BS). Pre- and post-brushing values of Knoop indentation length (5 indentations each sample) were measured and mean enamel loss was calculated from the change in indentation depth. Within- and between-group comparisons were performed by ANOVA and t-test followed by Bonferroni-correction. Enamel loss of acid-softened surfaces was significantly influenced by the brushing load applied and was mostly significantly higher in group D (10-1000 BS: 225-462 nm) compared to A (10-1000 BS: 164-384), B (10-1000 BS: 175-370 nm) and C (10-1000 BS: 191-396 nm). Abrasion of acid-softened enamel was fourfold higher compared to sound surfaces. Sound enamel was significantly influenced by the brushing force at 20-200 brushing strokes only, but revealed no significant differences between groups A-D. Brushing load influences abrasion of briefly eroded enamel, but might be of minor importance for abrasion of sound enamel surfaces.

Stereoregular polyacrylamide and its copolymer brushes: Preparation and surface characters

NASA Astrophysics Data System (ADS)

Jiang, Jianguo; Wang, Xiaoshu; Lu, Xiaoyan; Lu, Yun

2008-12-01

Two kinds of polymer brushes, the single one with stereospecific polyacrylamide (PAAM) chains and the dual-component one with random poly(methyl methacrylate) (PMMA) segments grafting from stereospecific PAAM chains, were prepared on silicon wafer for the first time by combining the immobilization of initiator and the stereospecific living radical in situ polymerization. With the addition of the Lewis acid AlCl 3 into the polymerization system, the PAAM brushes obtained exhibited an increased stereospecificity as well as a decreased hydrophilicity, which might attribute to the reduced thickness of PAAM brushes on the silicon wafer and the handicap of the free rotation of the stereospecific molecular chain. The smoother surface morphology of the stereospecific PAAM brushes shown in AFM images was in good agreement with the experimental data of water contact angle. Also, block amphiphilic copolymer brushes were prepared with the stereospecific PAAM formed first on silicon wafer as the anchored-initiator and revealed a novel surface self-assembly behavior after being treated with different solvent such as toluene or water. The stereospecificity of PAAM chains in the polymer brushes could be modulated by adjusting reaction conditions according to the requirement of applications for surface hydrophilicity.

A Brush-Creeper

ERIC Educational Resources Information Center

Mak, Se-yuen; Wong, Siu-ling

2006-01-01

In this note, we introduce a simple homemade toy called the brush-creeper, which can glide forward with no propellers, limbs, wheels, and seemingly no movement of any kind that can push forward against the ground. The toy arouses pupils' interest and their incentive to ask "Why?" in lessons related to friction.

Efficient Energy Conversion by Grafting Nanochannels with End-charged Stimuli-responsive Polyelectrolyte Brush

NASA Astrophysics Data System (ADS)

Chen, Guang; Das, Siddhartha

2017-11-01

Polyelectrolyte (PE) brushes have aroused increasing attention in applications in energy conversion and chemical sensing due to the environmentally-responsive and designable nature. PE brushes are charged polymer chains densely grafted on solid-liquid interfaces. By designing copolymeric systems, one can localize the ionizable sites at the brush tip in order to get end-charged PE brushes. Such brushes demonstrate anomalous shrinking/swelling behaviors with tunable environmental parameters such as pH and salt concentration. In this study, we probe the conformation and electrostatics of such PE brush systems with various size, grafting density and charge distribution, and exploit the electrochemomechanical energy conversion capabilities of nanochannels grafted with such PE brush systems. Our results indicate that the presence of the end-charged PE brush layer can massively enhance the streaming potential mediated energy conversion efficiency, and the improvement is more significant in strongly ionic solution.

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

PubMed

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.

Inhibitory effect of hydrophilic polymer brushes on surface-induced platelet activation and adhesion.

PubMed

Zou, Yuquan; Lai, Benjamin F L; Kizhakkedathu, Jayachandran N; Brooks, Donald E

2010-12-08

Poly(N,N-dimethylacrylamide) (PDMA) brushes are successfully grown from unplasticized poly(vinyl chloride) (uPVC) by well-controlled surface-initiated atom transfer radical polymerization (SI-ATRP). Molecular weights of the grafted PDMA brushes vary from ≈ 35,000 to 2,170000 Da, while the graft density ranges from 0.08 to 1.13 chains · nm(-2). The polydispersity of the grafted PDMA brushes is controlled within 1.20 to 1.80. Platelet activation (expression of CD62) and adhesion studies reveal that the graft densities of the PDMA brushes play an important role in controlling interfacial properties. PDMA brushes with graft densities between 0.35 and 0.50 chains · nm(-2) induce a significantly reduced platelet activation compared to unmodified uPVC. Moreover, the surface adhesion of platelets on uPVC is significantly reduced by the densely grafted PDMA brushes. PDMA brushes that have high molecular weights lead to a relatively lower platelet activation compared to low-molecular-weight brushes. However, the graft density of the brush is more important than molecular weight in controlling platelet interactions with PVC. PDMA brushes do not produce any significant platelet consumption in platelet rich plasma. Up to a seven-fold decrease in the number of platelets adhered on high graft density brushes is observed compared to the bare PVC surface. Unlike the bare PVC, platelets do not form pseudopodes or change morphology on PDMA brush-coated surfaces. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Critique of the Brushing for Life Programme

ERIC Educational Resources Information Center

Downer, Martin C.; Drugan, Caroline S.; Blinkhorn, Anthony S.

2006-01-01

Background and objective: Brushing for Life is intended to promote regular brushing of children's teeth with fluoride toothpaste. The programme is delivered by health visitors who provide toothbrushes, toothpaste and dental health education material at children's 8, 18 and 36 month development checks. The purpose of the present paper was to…

Short communication: use of a mechanical brush by Holstein dairy cattle around parturition.

PubMed

Newby, Nathalie C; Duffield, Todd F; Pearl, David L; Leslie, Ken E; LeBlanc, Stephen J; von Keyserlingk, Marina A G

2013-04-01

Grooming is a normal behavior that may contribute to relief of stress. The purpose of this study was to investigate the effect of access to a mechanical brush on auto-grooming behavior in parturient cows. The hypothesis was that cows would increase the total time spent scratching using the brush if they had access to a brush around the time of calving, whereas auto-grooming would be lower for the brush group compared with the no-brush group. The use of a mechanical brush was analyzed both in a group-housed pen (72 to 48 h before calving) and in an individual maternity pen (6h before to 6h after calving) in 16 multiparous Holstein cows. In the maternity pen, cows were randomly assigned to have access to the brush or not. The provision of a mechanical brush in the individual maternity pen did not change the amount of time spent auto-grooming but cows did use the brush before calving and after the calf was removed. Despite being housed in pens containing a brush, cows failed to use it when the calf was present. However, cows with access to a brush spent more time licking their calves in the first hour postcalving (β=8.7 min; 95% confidence interval: 1.5, 15.8) than cows that did not have access to a brush. Regardless of treatment, cows increased the time spent auto-grooming and scratching following separation of their newborn calf (β=1.4 min; 95% confidence interval: 0.46, 2.3 and β=0.07 min; 95% confidence interval: 0.02, 0.12, respectively). Further research is warranted to investigate possible benefits of mechanical brush devices at the time of calving, particularly for cows that experience difficult calving and require manual or mechanical assistance. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Comparison between observed children's tooth brushing habits and those reported by mothers.

PubMed

Martins, Carolina C; Oliveira, Maria J; Pordeus, Isabela A; Paiva, Saul M

2011-09-03

Information bias can occur in epidemiological studies and compromise scientific outcomes, especially when evaluating information given by a patient regarding their own health. The oral habits of children reported by their mothers are commonly used to evaluate tooth brushing practices and to estimate fluoride intake by children. The aim of the present study was to compare observed tooth-brushing habits of young children using fluoridated toothpaste with those reported by mothers. A sample of 201 mothers and their children (aged 24-48 months) from Montes Claros, Brazil, took part in a cross-sectional study. At day-care centres, the mothers answered a self-administered questionnaire on their child's tooth-brushing habits. The structured questionnaire had six items with two to three possible answers. An appointment was then made with each mother/child pair at day-care centres. The participants were asked to demonstrate the tooth-brushing practice as usually performed at home. A trained examiner observed and documented the procedure. Observed tooth brushing and that reported by mothers were compared for overall agreement using Cohen's Kappa coefficient and the McNemar test. Cohen's Kappa values comparing mothers' reports and tooth brushing observed by the examiner ranged from poor-to-good (0.00-0.75). There were statistically significant differences between observed tooth brushing habits and those reported by mothers (p < 0.001). When observed by the examiner, the frequencies of dentifrice dispersed on all bristles (35.9%), children who brushed their teeth alone (33.8%) and those who did not rinse their mouths during brushing (42.0%) were higher than those reported by the mothers (12.1%, 18.9% and 6.5%, respectively; p < 0.001). In general, there was low agreement between observed tooth brushing and mothers' reports. Moreover, the different methods of estimation resulted in differences in the frequencies of tooth brushing habits, indicative of reporting bias. Data

Comparison between observed children's tooth brushing habits and those reported by mothers

PubMed Central

2011-01-01

Background Information bias can occur in epidemiological studies and compromise scientific outcomes, especially when evaluating information given by a patient regarding their own health. The oral habits of children reported by their mothers are commonly used to evaluate tooth brushing practices and to estimate fluoride intake by children. The aim of the present study was to compare observed tooth-brushing habits of young children using fluoridated toothpaste with those reported by mothers. Methods A sample of 201 mothers and their children (aged 24-48 months) from Montes Claros, Brazil, took part in a cross-sectional study. At day-care centres, the mothers answered a self-administered questionnaire on their child's tooth-brushing habits. The structured questionnaire had six items with two to three possible answers. An appointment was then made with each mother/child pair at day-care centres. The participants were asked to demonstrate the tooth-brushing practice as usually performed at home. A trained examiner observed and documented the procedure. Observed tooth brushing and that reported by mothers were compared for overall agreement using Cohen's Kappa coefficient and the McNemar test. Results Cohen's Kappa values comparing mothers' reports and tooth brushing observed by the examiner ranged from poor-to-good (0.00-0.75). There were statistically significant differences between observed tooth brushing habits and those reported by mothers (p < 0.001). When observed by the examiner, the frequencies of dentifrice dispersed on all bristles (35.9%), children who brushed their teeth alone (33.8%) and those who did not rinse their mouths during brushing (42.0%) were higher than those reported by the mothers (12.1%, 18.9% and 6.5%, respectively; p < 0.001). Conclusions In general, there was low agreement between observed tooth brushing and mothers' reports. Moreover, the different methods of estimation resulted in differences in the frequencies of tooth brushing habits

Alcohol versus brush PRK: visual outcomes and adverse effects.

PubMed

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.

Ordered quasi-two-dimensional structure of nanoparticles in semiflexible ring polymer brushes under compression

NASA Astrophysics Data System (ADS)

Hua, Yunfeng; Deng, Zhenyu; Jiang, Yangwei; Zhang, Linxi

2017-06-01

Molecular dynamics simulations of a coarse-grained bead-spring model of ring polymer brushes under compression are presented. Flexible polymer brushes are always disordered during compression, whereas semiflexible polymer brushes tend to be ordered under sufficiently strong compression. Further, the polymer monomer density of the semiflexible polymer brush is very high near the brush surface, inducing a peak value of the free energy near the surface. Therefore, when nanoparticles are compressed in semiflexible ring polymer brushes, they tend to exhibit a closely packed single-layer structure between the brush surface and the impenetrable wall, and a quasi-two-dimensional ordered structure near the brush surface is formed under strong compression. These findings provide a new approach to designing responsive applications.

Tension Amplification in Molecular Brushes in Solutions and on Substrates

PubMed Central

Panyukov, Sergey; Zhulina, Ekaterina B.; Sheiko, Sergei S.; Randall, Greg C.; Brock, James; Rubinstein, Michael

2009-01-01

Molecular bottle-brushes are highly branched macromolecules with side chains densely grafted to a long polymer backbone. The brush-like architecture allows focusing of the side-chain tension to the backbone and its amplification from the picoNewton to nanoNewton range. The backbone tension depends on the overall molecular conformation and the surrounding environment. Here we study the relation between the tension and conformation of the molecular brushes in solutions, melts, and on substrates. In solutions, we find that the backbone tension in dense brushes with side chains attached to every backbone monomer is on the order of f0N3/8 in athermal solvents, f0N1/3 in θ-solvents, and f0 in poor solvents and melts, where N is the degree of polymerization of side chains, f0≃ kBT/b is the maximum tension in side chains, b is the Kuhn length, kB is Boltzmann constant, and T is absolute temperature. Depending on the side chain length and solvent quality, molecular brushes in solutions develop tension on the order of 10–100 picoNewtons, which is sufficient to break hydrogen bonds. Significant amplification of tension occurs upon adsorption of brushes onto a substrate. On a strongly attractive substrate, maximum tension in the brush backbone is ~ f0N, reaching values on the order of several nanoNewtons which exceed the strength of a typical covalent bond. At low grafting density and high spreading parameter the cross-sectional profile of adsorbed molecular brush is approximately rectangular with thicknes ~bA/S, where A is the Hamaker constant and S is the spreading parameter. At a very high spreading parameter (S > A), the brush thickness saturates at monolayer ~ b. At a low spreading parameter, the cross-sectional profile of adsorbed molecular brush has triangular tent-like shape. In the cross-over between these two opposite cases, covering a wide range of parameter space, the adsorbed molecular brush consists of two layers. Side chains in the lower layer gain surface

Effect of dielectric discontinuity on a spherical polyelectrolyte brush

NASA Astrophysics Data System (ADS)

Tergolina, Vinicius B.; dos Santos, Alexandre P.

2017-09-01

In this paper we perform molecular dynamics simulations of a spherical polyelectrolyte brush and counterions in a salt-free medium. The dielectric discontinuity on the grafted nanoparticle surface is taken into account by the method of image charges. Properties of the polyelectrolyte brush are obtained for different parameters, including valency of the counterions, radius of the nanoparticle, and the brush total charge. The monovalent counterions density profiles are obtained and compared with a simple mean-field theoretical approach. The theory allows us to obtain osmotic properties of the system.

Evaluation of the tooth brushing skills in children aged 6-12 years.

PubMed

Pujar, P; Subbareddy, V V

2013-08-01

To evaluate the tooth brushing skills in children aged between 6 and 12 years and its relation with age, type of grip used, duration of brushing and gender. A total of 105 children aged between 6 and 12 years were divided into seven groups and their plaque scores, type of grip used and duration of brushing were assessed. The most preferred grip was the distal oblique (58.1 %). Oblique, distal oblique and power grips were more efficient (plaque reduction up to 70 %). Plaque removal efficacy improved with age (57 % in 6-year-olds and 82 % in 12-year-old children). Plaque reduction was greater when the duration of brushing was longer (82 % plaque reduction when the brushing time was >2.5 min). Overall, the mean duration of tooth brushing in children aged 6-12 years was 1.71 min (103 s). Tooth brushing skills improved with age and the duration of tooth brushing made a significant difference to the oral hygiene status of the child. The type of grip used and gender did not influence tooth brushing ability in this group of children. Tooth brushing skills were low in children younger than 10 years of age. Hence, parental supervision is considered necessary and recommended until 10 years of age.

Synthesis and characterization of poly(3-sulfopropylmethacrylate) brushes for potential antibacterial applications.

PubMed

Ramstedt, Madeleine; Cheng, Nan; Azzaroni, Omar; Mossialos, Dimitris; Mathieu, Hans Jörg; Huck, Wilhelm T S

2007-03-13

This article describes the aqueous atom transfer radical polymerization synthesis of poly(3-sulfopropylmethacrylate) brushes onto gold and Si/SiO2 surfaces in a controlled manner. The effect of Cu(I)/Cu(II) ratio was examined, and a quartz crystal microbalance was used to study the kinetics of the brush synthesis. The synthesized brushes displayed a thickness from a few nanometers to several hundred nanometers and were characterized using atomic force microscopy, ellipsometry, Fourier transform infrared spectroscopy (FTIR), contact angle measurements, and X-ray photoelectron spectroscopy (XPS). The as-synthesized sulfonate brushes had very good ion-exchange properties for the ions tested in this study, i.e., Na+, K+, Cu2+, and Ag+. FTIR and XPS show that the metal ions are coordinating to sulfonate moieties inside the brushes. The brushes were easily loaded with silver ions, and the effect of silver ion concentration on silver loading of the brush was examined. The silver-loaded brushes were shown to be antibacterial toward both gram negative and gram positive bacteria. The silver leaching was studied through leaching experiments into water, NaNO3, and NaCl (physiological medium). The results from these leaching experiments are compared and discussed in the article.

Comparison of Saudi child versus parent-report of child tooth-brushing practices.

PubMed

Salama, F; Abobakr, I; Al-Khodair, N; Al-Wakeel, M

2016-01-01

This cross-sectional study compared Saudi children's tooth-brushing practices as reported by children and parents and then matched the agreement of reports. A sample of 100 Saudi parents and their children of ages 8-12 years participated in this cross-sectional investigation. A self-administered structured questionnaire regarding the current tooth-brushing practice and habits at home was filled by the child. The same questionnaire was filled independently by parents. Mothers were more likely to teach children about tooth-brushing and fathers were minimally helping children during tooth-brushing. Mothers were the first to teach the children and approximately 33% of the children started brushing their teeth by age 5. Children and parents reported that children clean their teeth using a tooth-brush (73.74% and 76.77%), miswak (5.05% and 5.05%), or both (21.21% and 18.18%), respectively. There was some agreement between reported tooth-brushing practice of children and their parents. It is important to question both the child and parent regarding oral hygiene practice and compare their answers to get more broad knowledge about their practices. Approximately, one-third of the children started brushing their teeth by age 5, which differs from recommended oral hygiene practices.

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

NASA Technical Reports Server (NTRS)

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.

Physical characteristics of some northern California brush fuels

Treesearch

Clive M. Countryman

1982-01-01

Brush species make up much of the fuel load in forested wildlands. Basic physical and chemical characteristics of these species influence ease of ignition, rate of fire spread, burning time, and fire intensity. Quantitative knowledge of the variations in brush characteristics is essential to progress in fire control and effective use of fire in wildland management....

Chemical control of brush in ponderosa pine forests of central Oregon.

Treesearch

Walter G. Dahms

1961-01-01

The many acres of forest land that are occupied by brush in central Oregon represent a large-scale waste of timber-growing capacity and a major economic loss to the area. Although large brushfields devoid of tree growth present the most spectacular examples of loss, less obvious but equally important brush problems are common in established timber stands. Brush...

75 FR 39706 - Natural Bristle Paint Brushes From China

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-12

... INTERNATIONAL TRADE COMMISSION [Investigation No. 731-TA-244 (Third Review)] Natural Bristle Paint Brushes From China AGENCY: United States International Trade Commission. ACTION: Revised schedule for the... natural bristle paint brushes from China (75 FR 21347, April 23, 2010). On April 23, 2010, the domestic...

Design and Testing of High Performance Brushes.

DTIC Science & Technology

1983-05-01

brushes. Foil brushes were first develop- by P. Haney in his M.S. thesis research. David, before leaving for a position in industry as a research...inclusions [1, 31. However, well hclos the statlic yield stress. Even though neither the process wh Iich leads% to tlse nucleation of the Stres...Phenomenologicall) it has been cstalished [1.2] tic, deformattion, failurc ~cctur-; after some 10’ cycles. that. as a first step prior to fatigue crack nucleation

What information can frictional properties of polymer brushes tell us?

NASA Astrophysics Data System (ADS)

Zhang, Zhenyu; Moxey, Mark; Morse, Andrew; Armes, Steven; Lewis, Andrew; Geoghegan, Mark; Leggett, Graham

2013-03-01

We have used friction force microscopy (FFM) to quantitatively examine surface grown zwitterionic polymer brushes: poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC), and to establish the correlation between its frictional behaviour to other intrinsic properties. In a good solvent, it was found that the coefficient of friction (μ) decreased with increasing film thickness. We conclude that the amount of bound solvent increases as the brush length increases, causing the osmotic pressure to increase and yielding a reduced tendency for the brush layer to deform under applied load. When measured in a series of alcohol/water mixtures, a significant increase in μ was observed for ethanol/water mixtures at a volume fraction of 90%. This is attributed to brush collapse due to co-nonsolvency, leading to loss of hydration of the brush chains and hence substantially reduced lubrication. We show that single asperity contact mechanics is strongly dependent on solvent quality. Friction-load relationship was found linear in methanol (good solvent), but sub-linear in water and ethanol (moderate solvent).

Using goats to control brush regrowth on fuelbreaks

Treesearch

Lisle R. Green; Leonard A. Newell

1982-01-01

On fuelbreaks, herbicides have been the primary tool for controlling brush regrowth. Vegetation of low volume and low growth is maintained on these wide strips as an aid to firefighting safety. Goats are a promising alternative to herbicides, and may be the best tool available for controlling brush regrowth on fuelbreaks. They eat a wider variety of plants, and more...

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

PubMed

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.

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

NASA Astrophysics Data System (ADS)

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.

Macroion induced dehydration of weak polyelectrolyte brushes

NASA Astrophysics Data System (ADS)

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.

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

NASA Astrophysics Data System (ADS)

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.

Stimuli Responsive Morphological Changes of Pnipa Polymer Brushes Synthesized on Silicon Substrate

NASA Astrophysics Data System (ADS)

Huda, Muhammad Nurul; Kabir, A. N. M. Hamidul

2013-08-01

High-density polymer brushes were grown from the silicon surface by atom transfer radical polymerization of Poly(N-isopropylacrylamide) (PNIPA) at different polymerization conditions. PNIPA brushes were prepared using Copper (I) Chloride/tris(2-(dimetylamino)ethyl)amine (Me6TREN) as a catalytic system in DMSO at 20°C. Free polymer formed during the brush formation was characterized by gel permeation chromatography. The grafting densities up to 0.52 chains/nm2 were obtained. The layer thickness of polymer brush increases with the increase of conversion of the monomer conversion as well as polymerization time. Atomic force microscopy and air bubble contact angle under pH solution were employed to study the surface morphology, reversible conformational changes of and stimulus-response behavior. PNIPA brushes exhibited a different nanomorphology after treatment with different pH solution. It also revealed a unique reversible wetting behavior with pH. The reversible properties of the PNIPA brushes can be used to regulate the adsorption of the sulfonated PS nanoparticles.

Dendritic brushes under theta and poor solvent conditions

NASA Astrophysics Data System (ADS)

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.

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

PubMed

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.

Gingival condition and tooth-brushing behavior after alcohol consumption.

PubMed

Mizutani, S; Ekuni, D; Tomofuji, T; Yamane, M; Azuma, T; Iwasaki, Y; Morita, M

2015-08-01

Various studies have reported the relationship between alcohol consumption and gingival condition. However, they focus on the direct effects of alcohol consumption or alcohol sensitivity on gingival condition, and it is unclear how oral health behaviors relate these relationships. The aims of this study were to assess the inter-relationships between gingival condition, tooth-brushing behavior after drinking alcohol and alcohol sensitivity in university students who drink more than once per week on average. A total of 808 students (541 males, 267 females) that habitually consume alcohol were analyzed. The disease activity of gingival condition was assessed as the percentage of bleeding on probing (%BOP). Additional information regarding alcohol sensitivity and oral health behaviors, including tooth-brushing behavior after drinking, were also collected. Thirteen percent of the current participants reported neglecting tooth-brushing after drinking, and their alcohol consumption was higher than those who did not neglect tooth-brushing. Logistic regression analysis showed that high %BOP (%BOP ≥ 20) was associated with male (OR = 1.53; 95% CI, 1.01-2.33), neglect of tooth-brushing after drinking (OR = 2.60; 95% CI, 1.20-5.61) and debris index (OR = 8.38; 95% CI, 4.24-16.60) in participants with low alcohol sensitivity. In participants with high alcohol sensitivity, high %BOP was associated with debris index (OR = 7.60; 95% CI, 3.12-18.51), but not with any oral health behaviors. The study revealed that alcohol consumption was indirectly related to gingival disease activity through the neglect of tooth-brushing after drinking alcohol in university students with low alcohol sensitivity. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Computer simulations of the mechanical response of brushes on the surface of cancerous epithelial cells

NASA Astrophysics Data System (ADS)

Goicochea, A. Gama; Guardado, S. J. Alas

2015-08-01

We report a model for atomic force microscopy by means of computer simulations of molecular brushes on surfaces of biological interest such as normal and cancerous cervical epithelial cells. Our model predicts that the force needed to produce a given indentation on brushes that can move on the surface of the cell (called “liquid” brushes) is the same as that required for brushes whose ends are fixed on the cell’s surface (called “solid” brushes), as long as the tip of the microscope covers the entire area of the brush. Additionally, we find that cancerous cells are softer than normal ones, in agreement with various experiments. Moreover, soft brushes are found to display larger resistance to compression than stiff ones. This phenomenon is the consequence of the larger equilibrium length of the soft brushes and the cooperative association of solvent molecules trapped within the brushes, which leads to an increase in the osmotic pressure. Our results show that a careful characterization of the brushes on epithelial cells is indispensable when determining the mechanical response of cancerous cells.

Gingival abrasion and recession in manual and oscillating–rotating power brush users

PubMed Central

Rosema, NAM; Adam, R; Grender, JM; Van der Sluijs, E; Supranoto, SC; Van der Weijden, GA

2014-01-01

Objective To assess gingival recession (GR) in manual and power toothbrush users and evaluate the relationship between GR and gingival abrasion scores (GA). Methods 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. Results 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). Conclusions 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. PMID:24871587

Kidney and Phosphate Metabolism

PubMed Central

2008-01-01

The serum phosphorus level is maintained through a complex interplay between intestinal absorption, exchange intracellular and bone storage pools, and renal tubular reabsorption. The kidney plays a major role in regulation of phosphorus homeostasis by renal tubular reabsorption. Type IIa and type IIc Na+/Pi transporters are important renal Na+-dependent inorganic phosphate (Pi) transporters, which are expressed in the brush border membrane of proximal tubular cells. Both are regulated by dietary Pi intake, vitamin D, fibroblast growth factor 23 (FGF23) and parathyroid hormone. The expression of type IIa Na+/Pi transporter result from hypophosphatemia quickly. However, type IIc appears to act more slowly. Physiological and pathophysiological alteration in renal Pi reabsorption are related to altered brush border membrane expression/content of the type II Na+/Pi cotransporter. Many studies of genetic and acquired renal phosphate wasting disorders have led to the identification of novel genes. Two novel Pi regulating genes, PHEX and FGF23, play a role in the pathophysiology of genetic and acquired renal phosphate wasting disorders and studies are underway to define their mechanism on renal Pi regulation. In recent studies, sodium-hydrogen exchanger regulatory factor 1 (NHERF1) is reported as another new regulator for Pi reabsorption mechanism. PMID:24459526

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

PubMed Central

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

The Effects of a Brushing Procedure on Stereotypical Behavior

ERIC Educational Resources Information Center

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…

Monomer volume fraction profiles in pH responsive planar polyelectrolyte brushes

DOE PAGES

Mahalik, Jyoti P.; Yang, Yubo; Deodhar, Chaitra V.; ...

2016-03-06

Spatial dependencies of monomer volume fraction profiles of pH responsive polyelectrolyte brushes were investigated using field theories and neutron reflectivity experiments. In particular, planar polyelectrolyte brushes in good solvent were studied and direct comparisons between predictions of the theories and experimental measurements are presented. The comparisons between the theories and the experimental data reveal that solvent entropy and ion-pairs resulting from adsorption of counterions from the added salt play key roles in affecting the monomer distribution and must be taken into account in modeling polyelectrolyte brushes. Furthermore, the utility of this physics-based approach based on these theories for the predictionmore » and interpretation of neutron reflectivity profiles in the context of pH responsive planar polyelectrolyte brushes such as polybasic poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and polyacidic poly(methacrylic acid) (PMAA) brushes is demonstrated. The approach provides a quantitative way of estimating molecular weights of the polymers polymerized using surface-initiated atom transfer radical polymerization.« less

[Daily living activities and oral condition among care facility residents with severe intellectual disabilities. Comparative analyses between residents receiving tooth-brushing assistance and those not receiving tooth-brushing assistance].

PubMed

Chiwata, Kaoru; Takeda, Fumi

2007-06-01

To clarify 1) differences in daily living activities and oral condition among care facility residents with severe intellectual disabilities and 2) chronological changes in daily living activities and oral condition for residents receiving tooth-brushing assistance and those never receiving tooth-brushing assistance. Subjects were 44 residents at a care facility for individuals with severe intellectual disabilities, who underwent dental screening in July 1994 and October 2003. At each time point, daily living activities, behavior during oral health guidance, behavior during dental health screening and oral condition were compared between residents receiving tooth-brushing assistance (assistance group) and those not receiving tooth-brushing assistance (independent group). Furthermore, chronological changes were analyzed for residents requiring assistance at both screenings, those requiring assistance only at the second screening, and those not requiring assistance at either screening. 1) In the assistance group, 100% and 36.4% of residents were unable to brush their teeth independently in 1994 and 2003, respectively. Significant differences between the assistance and independent groups were observed in all items of behavior during dental health screening in 1994, but not in 2003. No significant intergroup differences in oral condition were observed in 1994, but differences were seen in 2003; when compared to the assistance group, the number of lost teeth was significantly higher in the independent group, while the number of remaining teeth was lower. 2) Regarding changes over the nine-year period, a significantly greater proportion of residents not requiring assistance at either screening and those requiring assistance only at the second screening finally required assistance in bathing. As for oral condition, no significant changes in healthy teeth were observed in residents requiring assistance at both screening time points, while significant increases in dental

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.

PubMed

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 <20,000. For the pit valve hypothesis, we formed pit valves in the intervessel pits in the short stem segments and measured the maximum liquid pressure up to which gases in bordered pits were retained. The threshold pressure ranged from 0.025 to 0.10 MPa. These values matched the theoretical value calculated from the geometry of the pit chamber (0.0692-0.101 MPa). Our results suggest that gas in the pits is retained by surface tension, even under substantial positive pressure to resolve gases in the refilling vessel, whereas the molecule size required for the pit membrane 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.

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

NASA Technical Reports Server (NTRS)

Kim, Rhyn H.

1994-01-01

Recently, a fluid turbine which has a brush attached to it has been designed and tested with water as fluid. The purpose of the turbine-brush is to clean up fouling in a tube. The Montreal Protocol prohibits the use of CFC products from refrigeration industry or from industry in general as a cleanser in 1996. Alternatives for the cleansers, devices or a combination of alternative devices with a cleanser should be found. One of the methods is to develop a device which cleans fouling with a cleaning medium. In this paper, we describe a turbine connected with a brush. However, the turbine with the brush should be simple and easy to install. This device is a combined small liquid turbine with a brush. The turbine is activated by the liquid flowing through the tube. Then the turbine turns the brush cleaning fouling along the tube. Based on the energy conservation and the Bernoulli equation along with an empirical relationship of drag force obtained from an experimental apparatus, a relationship of the rotational speed, the number of blades, and geometric variables of the turbine-brush was obtained. The predicted rotational speeds were compared with the experimental observations. Further work was recommended for improvements.

Monitoring the degrafting of polyelectrolyte brushes by using surface gradients

NASA Astrophysics Data System (ADS)

Ko, Yeongun; Genzer, Jan

Polymer brushes comprise densely grafted polymer chains on surfaces, which possess high stability and high concentration of reactive centers per unit area compared to physisorbed polymer film. Polymer brushes are employed in many applications, including anti-fouling surfaces, cell adhesive surfaces, responsive surfaces, low-friction surfaces, etc. Recently, researchers reported that charged (or chargeable) polymer brushes can be degrafted from substrate while incubated in buffer solutions. Based on previous experiments conducted in our group and by others, we assume that chain degrafting results from the hydrolysis of Si-O groups in head-group of the initiator and/or the ester groups in main body of the initiator. The kinetic of hydrolysis is affected by mechanical forces acting on the initiator. Those forces depend on the molecular weight and the grafting density of the brush, and the concentration and distribution of charges along the macromolecule (tuned by pH - for weak electrolytes - and concentration of external salt). In this work, we study the stability of poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) brushes in two solvents (ethanol and water) at various pH values in water and under different levels of external salt concentration. National Science Foundation.

Iran-Iraq Border Quake Region Imaged by NASA Satellite

NASA Image and Video Library

2017-11-15

On Sunday, Nov. 12, 2017, a magnitude 7.3 earthquake struck along the Iran-Iraq border near Halabjah, Iraq. The earthquake was felt as far away as Kuwait, Qatar, Turkey, Lebanon and Israel. Extensive damage and numerous casualties were reported in the area near the epicenter (yellow star on image). The earthquake occurred along the boundary between the Arabian and Eurasian tectonic plates. This is an earthquake-prone area, and has experienced many deadly earthquakes in the past. In this perspective-view image, bright red areas are crops in fields, pale red on mountain ridges are shrubs and trees, dark gray areas are traces of earlier brush fires, and gray and tan colors are different rock types. The image was acquired Sept. 8, 2017, and the star marks the earthquake epicenter at 34.9 degrees north, 45.9 degrees east. https://photojournal.jpl.nasa.gov/catalog/PIA22112

Impaired organic ion transport in proximal tubules of rats with Heymann nephritis.

PubMed

Park, E K; Hong, S K; Goldinger, J; Andres, G; Noble, B

1985-10-01

Organic ion transport across the basolateral membrane of proximal tubules was measured by means of the tissue slice technique in each of the four different stages of Heymann nephritis. Impairment of both organic anion and cation transport was detected early in Stage 2, and became more severe in Stage 3 of Heymann nephritis. The decreased transport function was associated with extensive damage to proximal tubule cells, including loss of brush border microvilli and basal infoldings. Despite these abnormalities of structure and function, oxygen consumption of proximal tubule cells remained essentially normal. Partial recovery of organic cation transport was noted late in Heymann nephritis (Stage 4). Recovery of the cation transport function was associated with a partial restoration of brush border microvilli and basal infoldings to proximal tubule cells. However, organic anion transport remained depressed throughout the entire course of disease. Impairment of organic ion transport in rats with Heymann nephritis appeared to result from damage to basolateral membrane transport elements rather than general deterioration of the metabolic machinery of proximal tubule cells. Decreased organic cation transport appeared to be the consequence of a reduction in the number of carrier sites, a phenomenon that could have resulted from decreased membrane surface area. However, the depression of organic anion transport was associated with decreased substrate affinity of the anion carrier, indicating that qualitative, rather than quantitative changes, were primarily responsible for that defect. Specific antibody-mediated damage to the anion transport elements in basolateral membranes of proximal tubules is postulated to occur in Heymann nephritis.

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

PubMed

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.

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

PubMed

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

Compression induced phase transition of nematic brush: A mean-field theory study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Jiuzhou; Zhang, Xinghua, E-mail: zhangxh@bjtu.edu.cn; Yan, Dadong, E-mail: yandd@bnu.edu.cn

2015-11-28

Responsive behavior of polymer brush to the external compression is one of the most important characters for its application. For the flexible polymer brush, in the case of low grafting density, which is widely studied by the Gaussian chain model based theory, the compression leads to a uniform deformation of the chain. However, in the case of high grafting density, the brush becomes anisotropic and the nematic phase will be formed. The normal compression tends to destroy the nematic order, which leads to a complex responsive behaviors. Under weak compression, chains in the nematic brush are buckled, and the bendingmore » energy and Onsager interaction give rise to the elasticity. Under deep compression, the responsive behaviors of the nematic polymer brush depend on the chain rigidity. For the compressed rigid polymer brush, the chains incline to re-orientate randomly to maximize the orientational entropy and its nematic order is destroyed. For the compressed flexible polymer brush, the chains incline to fold back to keep the nematic order. A buckling-folding transition takes place during the compressing process. For the compressed semiflexible brush, the chains are collectively tilted to a certain direction, which leads to the breaking of the rotational symmetry in the lateral plane. These responsive behaviors of nematic brush relate to the properties of highly frustrated worm-like chain, which is hard to be studied by the traditional self-consistent field theory due to the difficulty to solve the modified diffusion equation. To overcome this difficulty, a single chain in mean-field theory incorporating Monte Carlo simulation and mean-field theory for the worm-like chain model is developed in present work. This method shows high performance for entire region of chain rigidity in the confined condition.« less

Factors Affecting Oral Hygiene and Tooth Brushing in Preschool Children, Shiraz/Iran.

PubMed

S, Shaghaghian; M, Zeraatkar

2017-06-01

Inadequate tooth brushing and inappropriate oral hygiene can lead to dental caries, the most common chronic diseases of childhood with several side effects. To evaluate factors affecting on preschool children's oral hygiene and tooth brushing in Shiraz, Iran. In this cross-sectional study, we selected 453 children registered in Shiraz kindergartens in 2013 by randomized cluster sampling. The children's tooth brushing and oral hygiene were assessed using a reliable and valid questionnaire and Simplified Debris Index (DI-S), respectively. A dental student examined all the children in each kindergarten to determine their DI-S. The relationship between the children's demographic variables and their oral hygiene and tooth brushing status were evaluated. Tooth brushing for 272 children (71.2%) had been started after the age of 2 years. The teeth in 96 children (24.2%) had been brushed lower than once daily. The mean of the children's DI-S was 1.19 ± (0.77). The DI-S of only 126 children (31.8%) was found to be good and very good. After controlling the effect of confounding factors, we found that the children's tooth brushing frequency was significantly associated with the number of children in the family and mothers' employment status. The age at which tooth brushing had been started was significantly associated with the fathers' education. Furthermore, the DI-S was associated with children's age, number of the children in the family, and their mothers' education. Oral hygiene and tooth brushing of the preschool children were not in a desirable status. Interventional procedures, especially educational programs, are recommended for children and their parents. These programs seem to be more necessary for older children, low socioeconomic families, and families with more than one child.

Factors Affecting Oral Hygiene and Tooth Brushing in Preschool Children, Shiraz/Iran

PubMed Central

S, Shaghaghian; M, Zeraatkar

2017-01-01

Statement of Problem: Inadequate tooth brushing and inappropriate oral hygiene can lead to dental caries, the most common chronic diseases of childhood with several side effects. Objectives: To evaluate factors affecting on preschool children’s oral hygiene and tooth brushing in Shiraz, Iran Materials and Methods: In this cross-sectional study, we selected 453 children registered in Shiraz kindergartens in 2013 by randomized cluster sampling. The children’s tooth brushing and oral hygiene were assessed using a reliable and valid questionnaire and Simplified Debris Index (DI-S), respectively. A dental student examined all the children in each kindergarten to determine their DI-S. The relationship between the children’s demographic variables and their oral hygiene and tooth brushing status were evaluated. Results: Tooth brushing for 272 children (71.2%) had been started after the age of 2 years. The teeth in 96 children (24.2%) had been brushed lower than once daily. The mean of the children’s DI-S was 1.19 ± (0.77). The DI-S of only 126 children (31.8%) was found to be good and very good. After controlling the effect of confounding factors, we found that the children’s tooth brushing frequency was significantly associated with the number of children in the family and mothers’ employment status. The age at which tooth brushing had been started was significantly associated with the fathers’ education. Furthermore, the DI-S was associated with children’s age, number of the children in the family, and their mothers’ education. Conclusions: Oral hygiene and tooth brushing of the preschool children were not in a desirable status. Interventional procedures, especially educational programs, are recommended for children and their parents. These programs seem to be more necessary for older children, low socioeconomic families, and families with more than one child. PMID:28959771

Removal of metal ions and humic acids through polyetherimide membrane with grafted bentonite clay.

PubMed

Hebbar, Raghavendra S; Isloor, Arun M; Prabhu, Balakrishna; Inamuddin; Asiri, Abdullah M; Ismail, A F

2018-03-16

Functional surfaces and polymers with branched structures have a major impact on physicochemical properties and performance of membrane materials. With the aim of greener approach for enhancement of permeation, fouling resistance and detrimental heavy metal ion rejection capacity of polyetherimide membrane, novel grafting of poly (4-styrenesulfonate) brushes on low cost, natural bentonite was carried out via distillation-precipitation polymerisation method and employed as a performance modifier. It has been demonstrated that, modified bentonite clay exhibited significant improvement in the hydrophilicity, porosity, and water uptake capacity with 3 wt. % of additive dosage. SEM and AFM analysis showed the increase in macrovoides and surface roughness with increased additive concentration. Moreover, the inclusion of modified bentonite displayed an increase in permeation rate and high anti-irreversible fouling properties with reversible fouling ratio of 75.6%. The humic acid rejection study revealed that, PEM-3 membrane having rejection efficiency up to 87.6% and foulants can be easily removed by simple hydraulic cleaning. Further, nanocomposite membranes can be significantly employed for the removal of hazardous heavy metal ions with a rejection rate of 80% and its tentative mechanism was discussed. Conspicuously, bentonite clay-bearing poly (4-styrenesulfonate) brushes are having a synergistic effect on physicochemical properties of nanocomposite membrane to enhance the performance in real field applications.

PRDA-2 and 3 Brush Seal Development Programs at EG and G

NASA Technical Reports Server (NTRS)

Loewenthal, Robert G.

1996-01-01

EG&G Mechanical Components Technology Group R&D completed a Brush Seal Development Program under PRDA-2 in late 1992. We started the Advanced Brush Seal Development program, under PRDA-3, in 1993 and will complete it in 1996. Both programs have been funded by the United States Air Force. In the first program, we made significant gains in the area of tribopairs (bristle materials vs. shaft coatings) and the 'Low Hysteresis' design for brush seals. These were reported in two AIAA Propulsion Conference papers, and the 'Low Hysteresis' design has been patented. Seals were delivered for test in an Air Force demonstrator at Allison. In PRDA-3, goals are to increase the pressure sealing capability, and the surface speeds and temperatures at which brush seals can be used. We have conducted part of the design and testing and have tested brush seals successfully at more severe conditions than in the previous program. We are continuing with the program, and will complete it in time to furnish brush seals for an Air Force Demonstrator test in 1997.

Endoscopic transpapillary brush cytology and forceps biopsy in patients with hilar cholangiocarcinoma.

PubMed

Weber, Andreas; von Weyhern, Claus; Fend, Falko; Schneider, Jochen; Neu, Bruno; Meining, Alexander; Weidenbach, Hans; Schmid, Roland M; Prinz, Christian

2008-02-21

To evaluate the sensitivity of brush cytology and forceps biopsy in a homogeneous patient group with hilar cholangiocarcinoma. Brush cytology and forceps biopsy were routinely performed in patients with suspected malignant biliary strictures. Fifty-eight consecutive patients undergoing endoscopic retrograde cholangio-pancreatography (ERCP) including forceps biopsy and brush cytology in patients with hilar cholangiocarcinoma between 1995-2005. Positive results for malignancy were obtained in 24/58 patients (41.4%) by brush cytology and in 31/58 patients (53.4%) by forceps biopsy. The combination of both techniques brush cytology and forceps biopsy resulted only in a minor increase in diagnostic sensitivity to 60.3% (35/58 patients). In 20/58 patients (34.5%), diagnosis were obtained by both positive cytology and positive histology, in 11/58 (19%) by positive histology (negative cytology) and only 4/58 patients (6.9%) were confirmed by positive cytology (negative histology). Brush cytology and forceps biopsy have only limited sensitivity for the diagnosis of malignant hilar tumors. In our eyes, additional diagnostic techniques should be evaluated and should become routine in patients with negative cytological and histological findings.

Macroscopic lateral heterogeneity observed in a laterally mobile immiscible mixed polyelectrolyte-neutral polymer brush

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Hoyoung; Tsouris, Vasilios; Lim, Yunho

We studied mixed poly(ethylene oxide) (PEO) and poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes. The question we attempted to answer was: when the chain grafting points are laterally mobile, how will this lateral mobility influence the structure and phase behavior of the mixed brush? Three different model mixed PEO/PDMAEMA brush systems were prepared: (1) a laterally mobile mixed brush by spreading onto the air–water interface a mixture of poly(ethylene oxide)–poly(n-butyl acrylate) (PEO–PnBA) and poly(2-(dimethylamino)ethyl methacrylate)–poly(n-butyl acrylate) (PDMAEMA–PnBA) diblock copolymers (the specific diblock copolymers used will be denoted as PEO 113–PnBA 100 and PDMAEMA 118–PnBA 100, where the subscripts refer to the number-average degreesmore » of polymerization of the individual blocks), (2) a mobility-restricted (inseparable) version of the above mixed brush prepared using a PEO–PnBA–PDMAEMA triblock copolymer (denoted as PEO 113–PnBA 89–PDMAEMA 120) having respective brush molecular weights matched with those of the diblock copolymers, and (3) a different laterally mobile mixed PEO and PDMAEMA brush prepared from a PEO 113–PnBA 100 and PDMAEMA 200–PnBA 103 diblock copolymer combination, which represents a further more height-mismatched mixed brush situation than described in (1). These three mixed brush systems were investigated by surface pressure–area isotherm and X-ray (XR) reflectivity measurements. These experimental data were analyzed within the theoretical framework of a continuum self-consistent field (SCF) polymer brush model. The combined experimental and theoretical results suggest that the mobile mixed brush derived using the PEO 113–PnBA 100 and PDMAEMA 118–PnBA 100 combination (i.e., mixed brush System #1) undergoes a lateral macroscopic phase separation at high chain grafting densities, whereas the more height-mismatched system (System #3) is only microscopically phase separated under

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

PubMed

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.

Hydrologic Effects of Brush Management in Central Texas

NASA Astrophysics Data System (ADS)

Banta, J. R.; Slattery, R.

2011-12-01

Encroachment of woody vegetation into traditional savanna grassland ecosystems in central Texas has largely been attributed to land use practices of settlers, most notably overgrazing and fire suppression. Implementing brush management practices (removing the woody vegetation and allowing native grasses to reestablish in the area), could potentially change the hydrology in a watershed. The U.S. Geological Survey, in cooperation with several local, State, and Federal cooperators, studied the hydrologic effects of ashe juniper (Juniperus ashei) removal as a brush management conservation practice in the Honey Creek State Natural Area in Comal County, Tex. Two adjacent watersheds of 104 and 159 hectares were used in a paired study. Rainfall, streamflow, evapotranspiration (Bowen ratio method), and water quality data were collected in both watersheds. Using a hydrologic mass balance approach, rainfall was allocated to surface-water runoff, evapotranspiration, and groundwater recharge. Groundwater recharge was not directly measured, but estimated as the residual of the hydrologic mass balance. After hydrologic data were collected in both watersheds for 3 years, approximately 80 percent of the woody vegetation (ashe juniper) was selectively removed from the 159 hectare watershed (treatment watershed). Brush management was not implemented in the other (reference) watershed. Hydrologic data were collected in both watersheds for six years after brush management implementation. The resulting data were examined for differences in the hydrologic budget between the reference and treatment watersheds as well as between pre- and post-brush management periods to assess effects of the treatment. Preliminary results indicate there are differences in the hydrologic budget as well as water quality between the watersheds during pre- and post-treatment periods.

Effect of Salt Concentration on the pH Responses of Strong and Weak Polyelectrolyte Brushes.

PubMed

Zhang, Jian; Kou, Ran; Liu, Guangming

2017-07-11

Strong polyelectrolyte brushes (SPB) and weak polyelectrolyte brushes (WPB) have different origins with response to pH, which makes their pH-responsive properties sensitive to salt concentration in different ways. Herein, we have employed poly[2-(methacryloyloxy)ethyl trimethylammonium chloride] (PMETAC) and poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) brushes as model systems for SPB and WPB, respectively, to investigate the effect of salt concentration on the pH responses of SPB and WPB using several surface-sensitive techniques. The pH-responsive properties of the PMETAC brushes are governed by the reorganization of the interchain hydrogen bonds between the grafted chains, whereas the pH response of the PDMAEMA brushes is controlled by the charge of the grafted chains. The response of the properties of the PMETAC brushes including hydration, conformation, and surface wettability becomes weaker with increasing salt concentration induced by the competitive adsorption of counterions to the brushes between OH - and Cl - . The weakening of the pH response of the PMETAC brushes is more remarkable at the relatively high pH values. The pH response of the PDMAEMA brushes also exhibits a salt-concentration dependence. As the salt concentration increases, the weakening of the pH response of the PDMAEMA brushes is attributed to the decrease in osmotic pressure within the brushes at relatively low pH values.

Control of brushing variables for the in vitro assessment of toothpaste abrasivity using a novel laboratory model.

PubMed

Parry, Jason; Harrington, Edward; Rees, Gareth D; McNab, Rod; Smith, Anthony J

2008-02-01

Design and construct a tooth-brushing simulator incorporating control of brushing variables including brushing force, speed and temperature, thereby facilitating greater understanding of their importance in toothpaste abrasion testing methodologies. A thermostable orbital shaker was selected as a base unit and 16- and 24-specimen brushing rigs were constructed to fit inside, consisting of: a square bath partitioned horizontally to provide brushing channels, specimen holders for 25 mm diameter mounted specimens to fit the brushing channels and individually weighted brushing arms, able to support four toothbrush holders suspended over the brushing channels. Brush head holders consisted of individually weighted blocks of Delrin, or PTFE onto which toothbrush heads were fixed. Investigating effects of key design criteria involved measuring abrasion depths of polished human enamel and dentine. The brushing simulator demonstrated good reproducibility of abrasion on enamel and dentine across consecutive brushing procedures. Varying brushing parameters had a significant impact on wear results: increased brushing force demonstrated a trend towards increased wear, with increased reproducibility for greater abrasion levels, highlighting the importance of achieving sufficient wear to optimise accuracy; increasing brushing temperature demonstrated increased enamel abrasion for silica and calcium carbonate systems, which may be related to slurry viscosities and particle suspension; varying brushing speed showed a small effect on abrasion of enamel at lower brushing speed, which may indicate the importance of maintenance of the abrasive in suspension. Adjusting key brushing variables significantly affected wear behaviour. The brushing simulator design provides a valuable model system for in vitro assessment of toothpaste abrasivity and the influence of variables in a controlled manner. Control of these variables will allow more reproducible study of in vitro tooth wear processes.

Surface Modification of Nonwoven fabrics by Atmospheric Brush Plasma

NASA Astrophysics Data System (ADS)

Oksuz, Lutfi; Uygun, Emre; Bozduman, Ferhat; Yurdabak Karaca, Gozde; Asan, Orkun Nuri; Uygun Oksuz, Aysegul

2017-10-01

Polypropylene nonwoven fabrics (PPNF) are used in disposable absorbent articles, such as diapers, feminine care products, wipes. PPNF need to be wettable by water or aqueous-based liquid. Plasma surface treatment/modification has turned out to be a well-accepted method since it offers superior surface property enhancement than other chemical methods. 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 application. The purpose of this study was to reveal the effectiveness of non-thermal atmospheric plasma brush in surface wettability and modification of two different nonwoven surfaces.

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

NASA Astrophysics Data System (ADS)

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.

Cytologic detection of amyloid in duodenal and ureteral brushings.

PubMed

Korat, O; Yachnis, A T; Ernst, C S

1988-01-01

Two cases of amyloidosis diagnosed on cytology brush specimens are described. Gastrointestinal involvement in a patient with primary amyloidosis and renal involvement in a patient with multiple myeloma were diagnosed on duodenal and ureteral brush specimens, respectively. Familiarity with the staining characteristics of amyloid should increase it as a consideration in the differential diagnosis of certain specimen types.

Buckling Instabilities in Polymer Brush Surfaces via Postpolymerization Modification

DOE PAGES

Guo, Wei; Reese, Cassandra M.; Xiong, Li; ...

2017-10-30

We report a simple route to engineer ultrathin polymer brush surfaces with wrinkled morphologies using postpolymerization modification (PPM), where the length scale of the buckled features can be tuned using PPM reaction time. Here, we show that partial crosslinking of the outer layer of the polymer brush under poor solvent conditions is critical to obtain wrinkled morphologies upon swelling.

Black Lipid Membranes at Bifaces

PubMed Central

Ti Tien, H.

1968-01-01

Black lipid membranes (BLM) less than 90 A thick have been shown to be the most realistic approach to biological membrane models. This paper describes the formation characteristics, optical properties, and thermodynamics of BLM at water/oil/water bifaces. In particular, the nature of the Plateau-Gibbs border which supports the black membrane is analyzed in some detail. The formation of BLM at the biface involves a spontaneous reduction of the free energy of the system. As long as the integrity of the membrane is maintained, the limiting structure of the BLM represents the lowest free energy configuration. PMID:19873618

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

PubMed

Holstein, Bjørn E; Bast, Lotus Sofie; Brixval, Carina Sjöberg; Damsgaard, Mogens Trab

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. © 2015 S. Karger AG, Basel.

Discriminatory bio-adhesion over nano-patterned polymer brushes

NASA Astrophysics Data System (ADS)

Gon, Saugata

Surfaces functionalized with bio-molecular targeting agents are conventionally used for highly-specific protein and cell adhesion. This thesis explores an alternative approach: Small non-biological adhesive elements are placed on a surface randomly, with the rest of the surface rendered repulsive towards biomolecules and cells. While the adhesive elements themselves, for instance in solution, typically exhibit no selectivity for various compounds within an analyte suspension, selective adhesion of targeted objects or molecules results from their placement on the repulsive surface. The mechanism of selectivity relies on recognition of length scales of the surface distribution of adhesive elements relative to species in the analyte solution, along with the competition between attractions and repulsions between various species in the suspension and different parts of the collecting surface. The resulting binding selectivity can be exquisitely sharp; however, complex mixtures generally require the use of multiple surfaces to isolate the various species: Different components will be adhered, sharply, with changes in collector composition. The key feature of these surface designs is their lack of reliance on biomolecular fragments for specificity, focusing entirely on physicochemical principles at the lengthscales from 1 - 100 nm. This, along with a lack of formal patterning, provides the advantages of simplicity and cost effectiveness. This PhD thesis demonstrates these principles using a system in which cationic poly-L-lysine (PLL) patches (10 nm) are deposited randomly on a silica substrate and the remaining surface is passivated with a bio-compatible PEG brush. TIRF microscopy revealed that the patches were randomly arranged, not clustered. By precisely controlling the number of patches per unit area, the interfaces provide sharp selectivity for adhesion of proteins and bacterial cells. For instance, it was found that a critical density of patches (on the order of

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

NASA Astrophysics Data System (ADS)

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.

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

PubMed

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.

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

PubMed

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.

Molecular Design of Antifouling Polymer Brushes Using Sequence-Specific Peptoids

DOE PAGES

Lau, King Hang Aaron; Sileika, Tadas S.; Park, Sung Hyun; ...

2014-11-26

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 prevents nonspecific 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 platformmore » 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 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 are found to give rise to distinct but subtle differences in properties. In conclusion, the results also point to the dominant roles of the grafted chain density and chain length in determining the performance of antifouling polymer brushes.« less

Grafting density effects, optoelectrical properties and nano-patterning of poly(para-phenylene) brushes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Jihua; Alonzo, Jose; Yu, Xiang

2013-09-24

Well-defined conjugated polymers in confined geometries are challenging to synthesize and characterize, yet they are potentially useful in a broad range of organic optoelectronic devices such as transistors, light emitting diodes, solar cells, sensors, and nanocircuits. We report a systematic study of optoelectrical properties, grafting density effects, and nanopatterning of a model, end-tethered conjugated polymer system. Specifically, poly(para-phenylene) (PPP) brushes of various grafting density are created in situ by aromatizing well-defined, end-tethered poly(1,3-cyclohexadiene) (PCHD) “precursor brushes”. Furthermore, this novel precursor brush approach provides a convenient way to make and systematically control the grafting density of high molecular weight conjugated polymermore » brushes that would otherwise be insoluble. Finally, this allows us to examine how grafting density impacts the effective conjugation length of the conjugated PPP brushes and to adapt the fabrication method to develop spatially patterned conjugated brush systems, which is important for practical applications of conjugated polymer brushes.« less

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

PubMed

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.

Life at the border: Adaptation of proteins to anisotropic membrane environment

PubMed Central

Pogozheva, Irina D; Mosberg, Henry I; Lomize, Andrei L

2014-01-01

This review discusses main features of transmembrane (TM) proteins which distinguish them from water-soluble proteins and allow their adaptation to the anisotropic membrane environment. We overview the structural limitations on membrane protein architecture, spatial arrangement of proteins in membranes and their intrinsic hydrophobic thickness, co-translational and post-translational folding and insertion into lipid bilayers, topogenesis, high propensity to form oligomers, and large-scale conformational transitions during membrane insertion and transport function. Special attention is paid to the polarity of TM protein surfaces described by profiles of dipolarity/polarizability and hydrogen-bonding capacity parameters that match polarity of the lipid environment. Analysis of distributions of Trp resides on surfaces of TM proteins from different biological membranes indicates that interfacial membrane regions with preferential accumulation of Trp indole rings correspond to the outer part of the lipid acyl chain region—between double bonds and carbonyl groups of lipids. These “midpolar” regions are not always symmetric in proteins from natural membranes. We also examined the hydrophobic effect that drives insertion of proteins into lipid bilayer and different free energy contributions to TM protein stability, including attractive van der Waals forces and hydrogen bonds, side-chain conformational entropy, the hydrophobic mismatch, membrane deformations, and specific protein–lipid binding. PMID:24947665

Preparation of plasmonic vesicles from amphiphilic gold nanocrystals grafted with polymer brushes

PubMed Central

Song, Jibin; Huang, Peng; Chen, Xiaoyuan

2016-01-01

Gold nanovesicles contain multiple nanocrystals within a polymeric coating. The strong plasmonic coupling between adjacent nanoparticles in their vesicular shell makes ultrasensitive biosensing and bioimaging possible. In our laboratory, multifunctional plasmonic vesicles are assembled from amphiphilic gold nanocrystals (such as gold nanoparticles and gold nanorods) coated with mixed hydrophilic and hydrophobic polymer brushes or amphiphilic diblock co-polymer brushes. To fulfill the different requirements of biomedical applications, different polymers that are either pH=responsive, photoactive or biodegradable can be used to form the hydrophobic brush, while the hydrophilicity is maintained by polyethylene glycol (PEG). This protocol covers the preparation, surface functionalization and self-assembly of amphiphilic gold nanocrystals grafted covalently with polymer brushes. The protocol can be completed within 2 d. The preparation of amphiphilic gold nanocrystals, coated with amphiphilic diblock polymer brushes using a ‘grafting to’ method or mixed hydrophilic and hydrophobic polymer brushes using tandem ‘grafting to’ and ‘grafting from’ methods, is described. We also provide detailed procedures for the preparation and characterization of pH-responsive plasmonic gold nanovesicles from amphiphilic gold nanocrystals using a film-rehydration method that can be completed within ~3 d. PMID:27763624

Endoscopic transpapillary brush cytology and forceps biopsy in patients with hilar cholangiocarcinoma

PubMed Central

Weber, Andreas; von Weyhern, Claus; Fend, Falko; Schneider, Jochen; Neu, Bruno; Meining, Alexander; Weidenbach, Hans; Schmid, Roland M; Prinz, Christian

2008-01-01

AIM: To evaluate the sensitivity of brush cytology and forceps biopsy in a homogeneous patient group with hilar cholangiocarcinoma. METHODS: Brush cytology and forceps biopsy were routinely performed in patients with suspected malignant biliary strictures. Fifty-eight consecutive patients undergoing endoscopic retrograde cholangiopancreatography (ERCP) including forceps biopsy and brush cytology in patients with hilar cholangiocarcinoma between 1995-2005. RESULTS: Positive results for malignancy were obtained in 24/58 patients (41.4%) by brush cytology and in 31/58 patients (53.4%) by forceps biopsy. The combination of both techniques brush cytology and forceps biopsy resulted only in a minor increase in diagnostic sensitivity to 60.3% (35/58 patients). In 20/58 patients (34.5%), diagnosis were obtained by both positive cytology and positive histology, in 11/58 (19%) by positive histology (negative cytology) and only 4/58 patients (6.9%) were confirmed by positive cytology (negative histology). CONCLUSION: Brush cytology and forceps biopsy have only limited sensitivity for the diagnosis of malignant hilar tumors. In our eyes, additional diagnostic techniques should be evaluated and should become routine in patients with negative cytological and histological findings. PMID:18286693

Teach children to brush (image)

MedlinePlus

... child's overall good health. Without proper dental care tooth decay and gum disease can lead to serious problems such as cavities and gingivitis, swollen and bleeding gums. Regular visits to the dentist, brushing twice each day, and flossing, are ways to ...

Improved Steam Turbine Leakage Control with a Brush Seal Design

NASA Astrophysics Data System (ADS)

Turnquist, Norman; Chupp, Raymond E.; Pastrana, Ryan; Wolfe, Chris; Burnett, Mark

2002-10-01

This paper presents an improved steam turbine leakage control system with a brush seal design. The contents include: 1) Typical Design Characteristics; 2) Typical Brush Seal Locations; 3) Reduced Leakage Rates; 4) Performance Benefits; 5) System Considerations; 6) Rotor Dynamics; 7) Laboratory Tests and 8) Field Experience.

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

Code of Federal Regulations, 2010 CFR

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...

Brush potential curve tracer

DOEpatents

Finch, H.A.

1985-06-21

A device for analyzing commutating characteristics of a motor or generator includes a holder for supporting a plurality of probes adjacent a brush of the motor or generator. Measurements of electrical current characteristics of the probes provides information useful in analyzing operation of the machine. Methods for employing a device in accordance with the invention are also disclosed.

Quantifying the brush structure and assembly of mixed brush nanoparticles in solution

NASA Astrophysics Data System (ADS)

Koski, Jason; Frischknecht, Amalie

The arrangement of nanoparticles in a polymer melt or solution is critical to the resulting material properties. A common strategy to control the distribution of nanoparticles is to graft polymer chains onto the surface of the nanoparticles. An emerging strategy to further control the arrangement of nanoparticles is to graft polymer chains of different types and/or different lengths onto the surface of the nanoparticle, though this considerably increases the parameter space needed to describe the system. Theoretical models that are capable of predicting the assembly of nanoparticles in a melt or solution are thus desirable to guide experiments. In this talk, I will describe a recently developed non-equilibrium method that is appealing in its ability to tractably account for fluctuations and that can directly relate to experiments. To showcase the utility of this method, I apply it to mixed brush grafted nanoparticles in solution where fluctuations are prominent. Specifically, I investigate the role of experimentally relevant parameters on the structure of the brush and the corresponding effects on the assembly of the nanoparticles in solution. These results can be directly linked to experiments to help narrow the relevant parameter space for optimizing these materials.

The Effects of Tooth Brushing on Whole Salivary Flow Rate in Older Adults

PubMed Central

Trottier, K.; Garrick, R.; Mascarenhas, T.; Jang, Y.

2018-01-01

Objectives (1) To determine whether manual (MTB), or electric, tooth brushing (ETB) modulates whole salivary flow rate in older adults who are free of systemic disease. (2) To determine the duration of the brushing-related modulation of salivary flow rate. (3) To compare salivary flow rate modulation associated with MTB and ETB. Method Twenty-one adults aged 60 years and older participated in two experimental sessions during which they used a manual, or electric, toothbrush to brush their teeth, tongue, and palate. Whole salivary flow rates were determined using the draining method before, during, and after brushing. Differences in salivary flow rates across time periods, and between conditions, were examined using paired samples t-tests applying a Holm-Bonferroni sequential procedure (pcorr < 0.0045). The relationship between tooth brushing and age with respect to maximum salivary flow rate increase was examined using Pearson's correlation coefficient (p < 0.05). Results/Conclusion Whole salivary flow rates increased during, and for up to 5 minutes following, tooth brushing in adults aged 60 years and older who were free of systemic disease. The salivary effects of MTB and ETB were not significantly different. A moderate, positive correlation was observed between tooth-brushing-related maximum salivary flow rate increase and age. PMID:29682540

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

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 4 2011-10-01 2011-10-01 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 classified locations must meet N.F.P.A. 496-1974 “Standard for Purged and Pressurized Enclosures for...

Plastin 1 Binds to Keratin and Is Required for Terminal Web Assembly in the Intestinal Epithelium

PubMed Central

Grimm-Günter, Eva-Maria S.; Revenu, Céline; Ramos, Sonia; Hurbain, Ilse; Smyth, Neil; Ferrary, Evelyne; Louvard, Daniel; Robine, Sylvie

2009-01-01

Plastin 1 (I-plastin, fimbrin) along with villin and espin is a prominent actin-bundling protein of the intestinal brush border microvilli. We demonstrate here that plastin 1 accumulates in the terminal web and interacts with keratin 19, possibly contributing to anchoring the rootlets to the keratin network. This prompted us to investigate the importance of plastin 1 in brush border assembly. Although in vivo neither villin nor espin is required for brush border structure, plastin 1-deficient mice have conspicuous ultrastructural alterations: microvilli are shorter and constricted at their base, and, strikingly, their core actin bundles lack true rootlets. The composition of the microvilli themselves is apparently normal, whereas that of the terminal web is profoundly altered. Although the plastin 1 knockout mice do not show any overt gross phenotype and present a normal intestinal microanatomy, the alterations result in increased fragility of the epithelium. This is seen as an increased sensitivity of the brush border to biochemical manipulations, decreased transepithelial resistance, and increased sensitivity to dextran sodium sulfate-induced colitis. Plastin 1 thus emerges as an important regulator of brush border morphology and stability through a novel role in the organization of the terminal web, possibly by connecting actin filaments to the underlying intermediate filament network. PMID:19321664

Vision, healing brush, and fiber bundles

NASA Astrophysics Data System (ADS)

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.

Brush Plating of Nickel-Tungsten Alloy for Engineering Application

DTIC Science & Technology

2012-08-01

ASETS Defense ‘12 1 Brush Plating of Nickel-Tungsten Alloy for Engineering Application Zhimin Zhong & Sid Clouser Report Documentation Page Form...COVERED 00-00-2012 to 00-00-2012 4. TITLE AND SUBTITLE Brush Plating of Nickel-Tungsten Alloy for Engineering Application 5a. CONTRACT NUMBER...6 Surface morphology Visual appearance, scanning electron and optical microscope images. Smooth, fine grained, micro- cracked surface morphology

Potential effects of tooth-brushing on human dentin wear following exposure to acidic soft drinks.

PubMed

Choi, S; Park, K-H; Cheong, Y; Moon, S W; Park, Y-G; Park, H-K

2012-08-01

This study used scanning electron microscopy and atomic force microscopy to examine the short-term potential effects of brushing time and the start-time of tooth-brushing after demineralization on primary dentin wear in vitro. Thirty-six noncarious primary central incisors were assigned to 12 experimental groups. Exposure to cola drinks was used to initiate the demineralization process. Three brushing times (5, 15 and 30 s) and four start-times of brushing (0, 30, 60 and 120 min) after an erosive attack were used for the abrasion process. Tooth-brushing the softened dentin surface led to increases in the open tubular fraction and microstructural changes on the dentin surface. Brushing immediately after exposure to cola resulted in the greatest irreversible dentin loss, whereas brushing 60 or 120 min after pretreatment resulted in the least irreversible dentin loss. However, brushing time had no effect on the irreversible loss of dentin wear. Based on these experimental results, tooth-brushing should be performed at least 60 min after consuming a cola drink to achieve the desired tooth cleaning and avoid the introduction of surface lesions on dentin. © 2012 The Authors Journal of Microscopy © 2012 Wadsworth Center, New York State Department of Health.

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

PubMed

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.

Supporting awareness through collaborative brushing and linking of tabular data.

PubMed

Hajizadeh, Amir Hossein; Tory, Melanie; Leung, Rock

2013-12-01

Maintaining an awareness of collaborators' actions is critical during collaborative work, including during collaborative visualization activities. Particularly when collaborators are located at a distance, it is important to know what everyone is working on in order to avoid duplication of effort, share relevant results in a timely manner and build upon each other's results. Can a person's brushing actions provide an indication of their queries and interests in a data set? Can these actions be revealed to a collaborator without substantially disrupting their own independent work? We designed a study to answer these questions in the context of distributed collaborative visualization of tabular data. Participants in our study worked independently to answer questions about a tabular data set, while simultaneously viewing brushing actions of a fictitious collaborator, shown directly within a shared workspace. We compared three methods of presenting the collaborator's actions: brushing & linking (i.e. highlighting exactly what the collaborator would see), selection (i.e. showing only a selected item), and persistent selection (i.e. showing only selected items but having them persist for some time). Our results demonstrated that persistent selection enabled some awareness of the collaborator's activities while causing minimal interference with independent work. Other techniques were less effective at providing awareness, and brushing & linking caused substantial interference. These findings suggest promise for the idea of exploiting natural brushing actions to provide awareness in collaborative work.

Self-perceived oral health influences tooth brushing in preschool children.

PubMed

Agostini, Bernardo Antonio; Machry, Rômulo Vaz; Teixeira, Carlos Roberto da Silva; Piovesan, Chaiana; Oliveira, Marta Dutra Machado; Bresolin, Carmela Rampazzo; Ardenghi, Thiago Machado

2014-01-01

This study assessed the influence of socioeconomic and clinical factors, as well as parent's perception of child's oral health on the toothbrushing frequency of 0-5-year-old children. The study was carried out in Santa Maria, RS, Brazil, during the National Children's Vaccination Day, and 478 children aged 0-5 years were included. Data were collected by clinical examinations and a structured questionnaire, conducted by 15 calibrated examiners and 30 supports. A questionnaire was filled out by the parents with information about several socioeconomic indicators, perception of child's oral health and frequency of tooth brushing. The main outcome was collected by the question: "How many times a day do you brush your child's teeth?". Multivariable Poisson regression model taking into account the cluster sample was performed to assess the association between the predictors and outcome. Children whose parents related worse perception of child's oral health showed less tooth brushing frequency (PR 1.23; 1.06 - 1.43). Young children brush their teeth less than the older ones (PR 0.90; 0.84 - 0.96); and lack of visit to a dentist was predictor for less tooth brushing frequency (PR 1.29; 1.05 - 1.59). Parent's perception of child oral health influence children's healthy behaviors, supporting the evidence that psychosocial factors are strong predictors of children's oral health.

Molecular Velcro constructed from polymer loop brushes showing enhanced adhesion force

NASA Astrophysics Data System (ADS)

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.

Surface changes of enamel after brushing with charcoal toothpaste

NASA Astrophysics Data System (ADS)

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 (p<0.05) after brushing for an equivalent of one month and an equivalent of three months. Using toothpaste containing charcoal can increase the surface roughness of tooth enamel.

Effects of desensitizing toothpastes on the permeability of dentin after different brushing times: An in vitro study.

PubMed

Yang, Meng; Lin, Hong; Jiang, Ruodan; Zheng, Gang

2016-12-01

To investigate the effects of three commercially available desensitizing toothpastes on dentin permeability, and compare the efficacy of each product for reducing dentin permeability in the short term according to the frequency and duration of usage. 100 dentin discs with no caries were prepared from freshly extracted human third molar teeth. The dentin discs were brushed with three desensitizing toothpastes or with a non-desensitizing toothpaste and distilled water, which served as control. The 100 dentin slices were randomly divided into two groups (n= 50): one group underwent continuous brushing (brushed for 3 minutes continuously), and the other group underwent discontinuous brushing (brushed three times, each time for 1 minute). Then, the two groups were divided into five subgroups (n = 10) for the five brushing applications. Dentin permeability was measured with a hydraulic permeability system before and after brushing. All desensitizing toothpastes reduced dentin permeability significantly after treatment. Sensodyne Repair and Protect (calcium sodium phosphosilicate) and discontinuous brushing reduced dentin permeability significantly compared with continuous brushing. Dentin permeability values showed no significant difference between the three toothpastes after 3 minutes of continuous brushing. When comparing the three toothpastes under discontinuous brushing conditions after 3 minutes, Sensodyne Repair and Protect (calcium sodium phosphosilicate) reduced dentin permeability significantly. Sensodyne Repair and Protect (calcium sodium phosphosilicate) and discontinuous brushing reduced dentin permeability significantly compared with continuous brushing. Moreover, brushing with Sensodyne Repair and Protect (calcium sodium phosphosilicate) resulted in the lowest dentin permeability compared with those of the other two toothpastes. These results indicated that Sensodyne Repair and Protect may relieve dentin hypersensitivity.

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

PubMed

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.

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

PubMed

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.

Brush potential curve tracer

DOEpatents

Finch, Hilvan A.

1987-01-01

A device for analyzing commutating characteristics of a motor or generator includes a holder for supporting a plurality of probes adjacent a brush of the motor or generator. Measurements of electrical current characteristics in each of the probes provides information useful in analyzing operation of the machine. Methods for employing a device in accordance with the invention are also disclosed.

Assessment of parental tooth-brushing following instruction with single-headed and triple-headed toothbrushes.

PubMed

Telishevesky, Yoel S; Levin, Liran; Ashkenazi, Malka

2012-01-01

The purpose of this study was to evaluate the effect of toothbrush design on the ability of parents to effectively brush their children's teeth. Parents of children (mean age=5.1±0.75 years old) from 4 kindergarten schools were randomly assigned to receive instruction in brushing their children's teeth using a manual single-headed toothbrush (2 schools) or a triple-headed toothbrush (2 schools). The parents' ability to brush their children's teeth was evaluated according to a novel toothbrush performing skill index (Ashkenazi Index), based on 2 criteria: (1) placement of the toothbrush on each tooth segment to be brushed ("reach"); and (2) completion of enough strokes on each segment ("stay"). One month after instruction, tooth-brushing ability was re-evaluated and plaque index of the children's teeth was assessed. One month after instruction, parents using the triple-headed toothbrush received significantly higher scores on the tooth-brushing performance index (~86%), than did those in the single-headed group (~61%; P=.001). The plaque index was significantly higher in the single-headed group (0.97±0.38) vs the triple-headed group (0.72±0.29; P<.01). The tooth-brushing performance index correlated negatively with the plaque index (P<.01). A triple-headed toothbrush promotes more consistent tooth-brushing by parents than does a single-headed toothbrush.

Salt dependence of compression normal forces of quenched polyelectrolyte brushes

NASA Astrophysics Data System (ADS)

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.

The Conformation of Thermoresponsive Polymer Brushes Probed by Optical Reflectivity.

PubMed

Varma, Siddhartha; Bureau, Lionel; Débarre, Delphine

2016-04-05

We describe a microscope-based optical setup that allows us to perform space- and time-resolved measurements of the spectral reflectance of transparent substrates coated with ultrathin films. This technique is applied to investigate the behavior in water of thermosensitive polymer brushes made of poly(N-isopropylacrylamide) grafted on glass. We show that spectral reflectance measurements yield quantitative information about the conformation and axial structure of the brushes as a function of temperature. We study how parameters such as grafting density and chain length affect the hydration state of a brush, and provide one of the few experimental evidences for the occurrence of vertical phase separation in the vicinity of the lower critical solution temperature of the polymer. The origin of the hysteretic behavior of poly(N-isopropylacrylamide) brushes upon cycling the temperature is also clarified. We thus demonstrate that our optical technique allows for in-depth characterization of stimuli-responsive polymer layers, which is crucial for the rational design of smart polymer coatings in actuation, gating, or sensing applications.

The effect of multivalent counterions to the structure of highly dense polystyrene sulfonate brushes

DOE PAGES

Yu, Jing; Mao, Jun; Yuan, Guangcui; ...

2016-02-23

Surface tethered polyelectrolyte brushes are scientifically interesting and technologically relevant to many applications, ranging from colloidal stabilization to responsive and tunable materials to lubrication. Many applications operate in environments containing multi-valent ions, media in which our scientific understanding is not yet well-developed. In this paper, we synthesized high-density polystyrene sulfonate (PSS) brushes via surface initiated atom-transfer radical polymerization, and performed neutron reflectivity (NR) measurements to investigate and compare the effects of mono-valent Rb + and tri-valent Y 3+ counterions to the structure of the densely tethered PSS brushes. Our NR results show that in mono-valent RbNO 3 solution, the densemore » PSS brush retained its full thickness up to a salt concentration of 1 M, whereas it immediately collapsed upon adding 1.67 mM of tri-valent Y 3+. Increasing the concentration of Y 3+ beyond this level did not lead to any significant further structure change of the PSS brush. Finally, our findings demonstrate that the presence of multi-valent counterions can significantly alter the structure of polyelectrolyte brushes, in a manner different from mono-valent ions, which has implications for the functionality of the brushes.« less

"Border Sexualities, Border Families in Schools": Queering Education

ERIC Educational Resources Information Center

Ryan, John

2012-01-01

This essay reviews Maria Pallotta-Chiarolli's (2010) Lambda Award-winning monograph "Border Sexualities, Border Families in Schools", in which queer and mestizage pedagogies frame a groundbreaking and highly accessible exploration of the issues that sexual border dwellers experience. Her particular focus areas are bisexual "sexually fluid"…

21 CFR 884.1100 - Endometrial brush.

Code of Federal Regulations, 2010 CFR

2010-04-01

... endometrium (the mucosal lining of the uterus) by brushing its surface. This device is used to study... perforation, or a recent cesarean section, and (3) Design and testing: (i) The sampling component is covered...

21 CFR 884.1100 - Endometrial brush.

Code of Federal Regulations, 2011 CFR

2011-04-01

... endometrium (the mucosal lining of the uterus) by brushing its surface. This device is used to study... perforation, or a recent cesarean section, and (3) Design and testing: (i) The sampling component is covered...

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

NASA Astrophysics Data System (ADS)

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.

Enzyme-mimicking polymer brush-functionalized surface for combating biomaterial-associated infections

NASA Astrophysics Data System (ADS)

Jiang, Rujian; Xin, Zhirong; Xu, Shiai; Shi, Hengchong; Yang, Huawei; Song, Lingjie; Yan, Shunjie; Luan, Shifang; Yin, Jinghua; Khan, Ather Farooq; Li, Yonggang

2017-11-01

Biomaterial-associated infections critically compromise the functionality and performance of the medical devices, and pose a serious threat to human healthcare. Recently, natural DNase enzyme has been recognized as a potent material to prevent bacterial adhesion and biofilm formation. However, the vulnerability of DNase dramatically limits its long-term performance in antibacterial applications. In this work, DNase-mimicking polymer brushes were constructed to mimic the DNA-cleavage activity as well as the macromolecular scaffold of the natural DNase. The bacteria repellent efficacy of DNase-mimicking polymer brush-functionalized surface was comparable to that of the DNase-functionalized surface. More importantly, due to their inherent stability, DNase-mimicking polymer brushes presented the much better performance in inhibiting bacterial biofilm development for prolonged periods of time, as compared to the natural DNase. The as-developed DNase-mimicking polymer brush-functionalized surface presents a promising approach to combat biomaterial-associated infections.

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

PubMed

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.

Role of rat sodium/phosphate cotransporters in the cell membrane transport of arsenate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Villa-Bellosta, Ricardo; Sorribas, Victor

2008-10-01

Inorganic arsenate (As{sup V}) is a common contaminant of underground water. Following oral exposure, it is assumed that As{sup V} is distributed and crosses cell membranes through inorganic phosphate (Pi) transporters. We have tested this hypothesis by studying the inhibition of rat Na/Pi cotransporters by As{sup V} in Xenopus laevis oocytes and in several rat tissues. The ubiquitously expressed type III Pi transporters (PiT-1 and PiT-2) showed a low affinity for As{sup V} (K{sub i} {approx} 3.8 mM), similar to the Pi transport system in aortic vascular smooth muscle cells (K{sub i} 1.5 mM). The type II renal isoforms, NaPi-IIamore » and NaPi-IIc, were also poorly inhibited by As{sup V} (K{sub i} {approx} 1 mM), similar to the Pi transport from kidney cortex brush-border membrane (BBM) vesicles. Conversely, the high-affinity intestinal transporter, NaPi-IIb, was very efficiently inhibited with a K{sub i} of 51 {mu}M, similar to the Pi transport from intestinal BBM vesicles. Taking into account the 1.1 mM Pi in blood and renal ultrafiltrate, and the nanomolar range of As{sup V} exposures, we have determined that the contribution by Na/Pi cotransporters to As{sup V} membrane transport is negligible, given that 10-15 mM As{sup V} would be necessary in these fluids to be significantly transported. Intestinal transport is an exception, because Pi competition is weak, thereby considering that its concentration in lumen mainly depends on low Pi levels from ingested fresh water, and because As{sup V} very efficiently inhibits Pi intestinal transport. Our data agree with current toxicokinetic knowledge, and they explain the asymmetric excretion of trivalent and pentavalent arsenic species into bile and urine.« less

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

PubMed

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.

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

PubMed

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.

Expression analysis of extracellular matrix components in brush biopsies of oral lesions.

PubMed

Driemel, Oliver; Kosmehl, Hartwig; Rosenhahn, Julia; Berndt, Alexander; Reichert, Torsten E; Zardi, Luciano; Dahse, Regine

2007-01-01

Oral brush biopsies have proved to be a promising new non-invasive methodology in the diagnosis of oral lesions. The extracellular matrix (ECM) molecules gamma2 chain of laminin-5 (L5gamma2), tenascin-c (Tn-C) and the fibronectin isoform containing EDB (EDB-fn) are involved in matrix remodeling during malignant transformation in oral carcinoma. Expression of L5gamma2, Tn-C and EDB-fn was analysed in brush biopsy-obtained cells of benign inflammatory or hyperproliferative lesions and primary oral squamous cell carcinoma (OSCC) using the Roche LightCycler 2.0 System. Oral carcinoma are detectable with mRNA resynthesis of the ECM molecules L5gamma2 and Tn-C in oral brush biopsies. EDB-fn mRNA was not detected--the stroma myofibroblasts are apparently a preferential source of EDB-fn and sampling by oral brush biopsy harvests epithelial cells and does not reach the cells which do express EDB-fn. The performance of gene expression analysis in brush biopsies is limited by a high RNase activity in the oral cavity.

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

NASA Astrophysics Data System (ADS)

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.

Smoking, tooth brushing and oral cleanliness among 15-year-olds in Tehran, Iran.

PubMed

Yazdani, Reza; Vehkalahti, Miira M; Nouri, Mahtab; Murtomaa, Heikki

2008-01-01

To assess smoking, tooth brushing and oral cleanliness and their relationships among 15-year-olds in Tehran, Iran. A cross-sectional study based on World Health Organization criteria and the methods of the Second International Collaborative Study was carried out in autumn 2004 among 15-year-olds (n=502) in Tehran. Data were based on a self-administered questionnaire and a clinical dental examination. Smokers comprised 5% of the boys and 2% of the girls (p = 0.02). Smoking was more common among students of less-educated parents (50% vs. 30%, p < 0.05). Of all students, 26% reported twice-daily tooth brushing; those of higher socio-economic backgrounds and girls did so more frequently. Of the smokers, 11% reported no tooth brushing compared to 6% of the non-smokers. Oral cleanliness was good for 13%, moderate for 32%, and poor for 55%; the rates associated positively with female gender (p = 0.002), having higher-educated parents (p = 0.03), and reporting a higher frequency of tooth brushing (p < 0.001). Those students reporting twice-daily tooth brushing had less dental plaque and gingival bleeding (p < or = 0.01) on both anterior and posterior teeth. In multivariable analyses, the best predictors for a good level of oral cleanliness were female gender (OR = 2.0) or twice-daily tooth brushing (OR = 1.7). Oral cleanliness and tooth brushing among 15-year-olds were at poor levels, particularly among boys. Such poor levels call for intensive attempts to enhance rates of twice-daily tooth brushing and to improve its quality. For this age group, anti-smoking purposes should be combined into school-based oral health promotion programmes as well.

Charged Polymer Brushes: Counterion Incorporation and Scaling Relations

NASA Astrophysics Data System (ADS)

Ahrens, Heiko; Förster, Stephan; Helm, Christiane A.

1998-11-01

Amphiphilic block copolymers consisting of a fluid hydrophobic and a polyelectrolyte part form monolayers at the air/water interface. With x-ray reflectivity it is shown that the hydrophobic block is a nm-thick melt, while the polyelectrolyte forms an osmotically swollen brush of constant thickness, independent of grafting density and with stochiometric counter ion incorporation. Only at high salt conditions (above 0.1 M), the brush shrinks and the thickness scales with the molecular area and the salt concentration (corrected for excluded volume interactions) with an exponent -1/3.

Metabolism of neuropeptides. Hydrolysis of the angiotensins, bradykinin, substance P and oxytocin by pig kidney microvillar membranes.

PubMed Central

Stephenson, S L; Kenny, A J

1987-01-01

Microvillar membranes derived from the brush border of the renal proximal tubule are very rich in peptidases. Pig kidney microvilli contain endopeptidase-24.11 associated with a battery of exopeptidases. The manner by which some neuropeptides are degraded by the combined attack of the peptidases of this membrane has been investigated. The contribution of individual peptidases was assessed by including inhibitors (phosphoramidon, captopril, amastatin and di-isopropyl fluorophosphate) with the membrane fraction when incubated with the peptides. Substance P, bradykinin and angiotensins I, II and III and insulin B-chain were rapidly hydrolysed by kidney microvilli. Oxytocin was hydrolysed much more slowly, but no products were detected from [Arg8]vasopressin or insulin under the conditions used for other peptides. The peptide bonds hydrolysed were identified and the contributions of the different peptidases were quantified. For each of the susceptible peptides, the main contribution came from endopeptidase-24.11 (inhibited by phosphoramidon). Peptidyl dipeptidase A (angiotensin-I-converting enzyme) was of less importance, even in respect of angiotensin I and bradykinin. When [2,3-Pro3,4-3H]bradykinin was also investigated at a lower concentration (20 nM), the conclusions in regard to the contributions of the two peptidases were unchanged. The possibility that endopeptidase-24.11 might attack within the six-residue disulphide-bridged rings of oxytocin and vasopressin was examined by dansyl(5-dimethylaminonaphthalene-1-sulphonyl)ation and by reduction and carboxymethylation of the products after incubation. Additional peptides were only observed after prolonged incubation, consistent with hydrolysis at the Tyr2-Ile3 and Tyr2-Phe3 bonds respectively. These results show that a range of neuropeptides are efficiently degraded by microvillar membranes and that endopeptidase-24.11 plays a key role in this process. PMID:2436610

Evaluation of Brushing as a Lunar Dust Mitigation Strategy for Thermal Control Surfaces

NASA Technical Reports Server (NTRS)

Gaier, James R.; Journey, Hhrissaundra; Christopher, Steven; Davis, Shanon

2011-01-01

Evaluation of brushing to remove lunar simulant dust from thermal control surfaces is described. First, strip brushes made with nylon, PTFE, or Thunderon bristles were used to remove JSC-1AF dust from AZ93 thermal control paint or aluminized FEP (AlFEP) thermal control surface under ambient laboratory conditions. Nylon and PTFE bristles removed a promising amount of dust from AZ93, and nylon and Thunderon bristles from AlFEP. But when these were tested under simulated lunar conditions in the lunar dust adhesion bell jar (LDAB), they were not effective. In a third effort, seven brushes made up of three different materials, two different geometries, and different bristle lengths and thicknesses were tested under laboratory conditions against AZ93 and AlFEP. Two of these brushes, the Zephyr fiberglass fingerprint brush and the Escoda nylon fan brush, removed over 90 percent of the dust, and so were tested in the fourth effort in the LDAB. They also performed well under these conditions recovering 80 percent or more of the original thermal performance (solar absorptance/thermal emittance) of both AZ93 and AgFEP after 20 strokes, and 90 or more percent after 200 strokes.

Development of the Upgraded DC Brush Gear Motor for Spacebus Platforms

NASA Technical Reports Server (NTRS)

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.

EPA blocks TNF-α-induced inhibition of sugar uptake in Caco-2 cells via GPR120 and AMPK.

PubMed

Castilla-Madrigal, Rosa; Barrenetxe, Jaione; Moreno-Aliaga, María J; Lostao, María Pilar

2018-03-01

The aim of the present work was to investigate in Caco-2 cells whether eicosapentaenoic acid (EPA), an omega-3 polyunsaturated fatty acid, could block the inhibitory effect of tumor necrosis factor-α (TNF-α) on sugar transport, and identify the intracellular signaling pathways involved. After pre-incubation of the Caco-2 cells with TNF-α and EPA for 1 hr, EPA prevented the inhibitory effect of the cytokine on α-methyl-d-glucose (αMG) uptake (15 min) and on SGLT1 expression at the brush border membrane, measured by Western blot. The ERK1/2 inhibitor PD98059 and the AMPK activator AICAR also prevented the inhibitory effect of TNF-α on both αMG uptake and SGLT1 expression. Interestingly, the AMPK inhibitor, Compound C, abolished the ability of EPA to prevent TNF-α-induced reduction of sugar uptake and transporter expression. The GPR120 antagonist, AH7614, also blocked the preventive effect of EPA on TNF-α-induced decrease of αMG uptake and AMPK phosphorylation. In summary, TNF-α inhibits αMG uptake by decreasing SGLT1 expression in the brush border membrane through the activation of ERK1/2 pathway. EPA prevents the inhibitory effect of TNF-α through the involvement of GPR120 and AMPK activation. © 2017 Wiley Periodicals, Inc.

Tooth brushing frequency in Mexican schoolchildren and associated socio-demographic, socioeconomic, and dental variables

PubMed Central

Casanova-Rosado, Alejandro José; Medina-Solís, Carlo Eduardo; Casanova-Rosado, Juan Fernando; Vallejos-Sánchez, Ana Alicia; Minaya-Sánchez, Mirna; Mendoza-Rodríguez, Martha; Márquez-Rodríguez, Sonia; Maupomé, Gerardo

2014-01-01

Background Tooth brushing (with fluoridated toothpaste) is the most cost-effective intervention in dentistry and it is widely recommended to preserve good oral health. We aimed to determine the frequency of tooth brushing and the variables associated with this practice in schoolchildren living in southeast Mexico. Material/Methods A cross-sectional study was carried out in 1644 schoolchildren, 6 to 13 years old. Questionnaires with socio-demographic, socioeconomic, and dental variables were administered to mothers/guardians of children. The dependent variable was the frequency of tooth brushing, which was categorized as 0 = tooth brushing less than once a day and 1 = tooth brushing at least once a day. A logistic regression model was used to evaluate the final results. Results Mean age was 9.06±2.02 years and 49.1% were girls. The prevalence of tooth brushing at least once a day was 49.8%. In the multivariate model, characteristics related to tooth brushing frequency (p<0.05) were: older age (OR=1.11), being female (OR=1.64), having a larger family (OR=0.87), having had a visit to a dentist during the year preceding the study (OR=1.37), and having had fluoride applications by a professional (OR=1.39). Conclusions The results suggested that different variables (demographic, socioeconomic and dental) are associated with the frequency of tooth brushing. Family size (proxy variable for socioeconomic status) may indicate certain oral health inequalities in this population. PMID:24907713

Tooth brushing frequency in Mexican schoolchildren and associated socio-demographic, socioeconomic, and dental variables.

PubMed

Casanova-Rosado, Alejandro José; Medina-Solís, Carlo Eduardo; Casanova-Rosado, Juan Fernando; Vallejos-Sánchez, Ana Alicia; Minaya-Sánchez, Mirna; Mendoza-Rodríguez, Martha; Márquez-Rodríguez, Sonia; Maupomé, Gerardo

2014-06-07

Tooth brushing (with fluoridated toothpaste) is the most cost-effective intervention in dentistry and it is widely recommended to preserve good oral health. We aimed to determine the frequency of tooth brushing and the variables associated with this practice in schoolchildren living in southeast Mexico. A cross-sectional study was carried out in 1644 schoolchildren, 6 to 13 years old. Questionnaires with socio-demographic, socioeconomic, and dental variables were administered to mothers/guardians of children. The dependent variable was the frequency of tooth brushing, which was categorized as 0 = tooth brushing less than once a day and 1 = tooth brushing at least once a day. A logistic regression model was used to evaluate the final results. Mean age was 9.06±2.02 years and 49.1% were girls. The prevalence of tooth brushing at least once a day was 49.8%. In the multivariate model, characteristics related to tooth brushing frequency (p<0.05) were: older age (OR=1.11), being female (OR=1.64), having a larger family (OR=0.87), having had a visit to a dentist during the year preceding the study (OR=1.37), and having had fluoride applications by a professional (OR=1.39). The results suggested that different variables (demographic, socioeconomic and dental) are associated with the frequency of tooth brushing. Family size (proxy variable for socioeconomic status) may indicate certain oral health inequalities in this population.

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.

PubMed

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.

Facilitators and barriers to twice daily tooth brushing among children with special health care needs

PubMed Central

Campanaro, Maria; Huebner, Colleen E.; Davis, Beth Ellen

2015-01-01

Purpose The oral hygiene routines of preschool-age children with special health care needs (CSHCN) were examined to identify caregiver behaviors and beliefs associated with twice daily tooth brushing. Methods Ninety caregivers of CSHCN, ages 23 to 62 months, were interviewed to determine supports or barriers to tooth brushing. Results Ninety-eight percent of caregivers had begun brushing their child’s teeth and half reported brushing twice daily. Caregivers’ brushing skills and the availability of child-friendly supplies were associated with twice daily versus less frequent brushing (p = .02). Conclusions This study adds insight into the challenges of establishing daily oral health care for children who must rely on others for their care. The facilitators and barriers to tooth brushing by caregivers of CSHCN are similar to those noted previously among parents of typically developing children. Efforts to improve all caregivers’ oral hygiene skills are needed. For caregivers of CSHCN, oral health teaching opportunities may exist among professionals who provide ongoing medical care, special services and therapies. PMID:24252060

Facilitators and barriers to twice daily tooth brushing among children with special health care needs.

PubMed

Campanaro, Maria; Huebner, Colleen E; Davis, Beth Ellen

2014-01-01

The oral hygiene routines of preschool-age children with special health care needs (CSHCN) were examined to identify caregiver behaviors and beliefs associated with twice daily tooth brushing. Ninety caregivers of CSHCN, ages 23 to 62 months, were interviewed to determine supports or barriers to tooth brushing. Ninety-eight percent of caregivers had begun brushing their child's teeth and half reported brushing twice daily. Caregivers' brushing skills and the availability of child-friendly supplies were associated with twice daily versus less frequent brushing (p = .02). This study adds insight into the challenges of establishing daily oral health care for children who must rely on others for their care. The facilitators and barriers to tooth brushing by caregivers of CSHCN are similar to those noted previously among parents of typically developing children. Efforts to improve all caregivers' oral hygiene skills are needed. For caregivers of CSHCN, oral health teaching opportunities may exist among professionals who provide ongoing medical care, special services and therapies. © 2014 Special Care Dentistry Association and Wiley Periodicals, Inc.

Friction, wear, and noise of slip ring and brush contacts for synchronous satellite use.

NASA Technical Reports Server (NTRS)

Lewis, N. E.; Cole, S. R.; Glossbrenner, E. W.; Vest, C. E.

1973-01-01

A program is being conducted for testing of slip rings for synchronous orbit application. Instrumentation systems necessary for monitoring electrical noise, friction, and brush wear at atmospheric pressure and at less than 50 nanotorr have been developed. A multiplex scheme necessary for the simultaneous recording of brush displacement, friction, and electrical noise has also been developed. Composite brushes consisting of silver-molybdenum disulfide-graphite and silver-niobium diselenide-graphite have been employed on rings of coin silver and rhodium plate. Brush property measurements made included measurement of density, electrical resistivity, shear strength, and microstructure.

Polyelectrolyte brushes grafted from cellulose nanocrystals using Cu-mediated surface-initiated controlled radical polymerization.

PubMed

Majoinen, Johanna; Walther, Andreas; McKee, Jason R; Kontturi, Eero; Aseyev, Vladimir; Malho, Jani Markus; Ruokolainen, Janne; Ikkala, Olli

2011-08-08

Herein we report the synthesis of cellulose nanocrystals (CNCs) grafted with poly(acrylic acid) (PAA) chains of different lengths using Cu-mediated surface initiated-controlled radical polymerization (SI-CRP). First, poly(tert-butylacrylate) (PtBA) brushes were synthesized; then, subsequent acid hydrolysis was used to furnish PAA brushes tethered onto the CNC surfaces. The CNCs were chemically modified to create initiator moieties on the CNC surfaces using chemical vapor deposition (CVD) and continued in solvent phase in DMF. A density of initiator groups of 4.6 bromine ester groups/nm(2) on the CNC surface was reached, suggesting a dense functionalization and a promising starting point for the controlled/living radical polymerization. The SI-CRP of tert-butylacrylate proceeded in a well-controlled manner with the aid of added sacrificial initiator, yielding polymer brushes with polydispersity values typically well below 1.12. We calculated the polymer brush grafting density to almost 0.3 chains/nm(2), corresponding to high grafting densities and dense polymer brush formation on the nanocrystals. Successful rapid acid hydrolysis to remove the tert-butyl groups yielded pH-responsive PAA-polyelectrolyte brushes bound to the CNC surface. Individually dispersed rod-like nanoparticles with brushes of PtBA or PAA were clearly visualized by AFM and TEM imaging.

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

NASA Astrophysics Data System (ADS)

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

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.

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

PubMed

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.

Protocol for measurement of enamel loss from brushing with an anti-erosive toothpaste after an acidic episode.

PubMed

Dehghan, Mojdeh; Vieira Ozorio, Jose Estevam; Chanin, Simon; Tantbirojn, Daranee; Versluis, Antheunis; Garcia-Godoy, Franklin

2017-01-01

Tooth erosion from an acidic insult may be exacerbated by toothbrushing. The purposes of this study were to develop an in vitro methodology to measure enamel loss after brushing immediately following an acidic episode and to investigate the effect of brushing with an anti-erosive toothpaste. The null hypotheses tested were that tooth erosion after brushing with the toothpaste would not be different from brushing with water and that a 1-hour delay before brushing would not reduce tooth erosion. Forty bovine enamel slabs were embedded, polished, and subjected to baseline profilometry. Specimens were bathed in hydrochloric acid for 10 minutes to simulate stomach acid exposure before post-acid profilometry. Toothbrushing was then simulated with a cross-brushing machine and followed by postbrushing profilometry. Group 1 was brushed with water; group 2 was brushed with a 50:50 toothpaste-water slurry; and groups 3 and 4 were immersed in artificial saliva for 1 hour before brushing with water or the toothpaste slurry, respectively. The depth of enamel loss was analyzed and compared using 1-way analysis of variance and post hoc testing (α = 0.05). Greater enamel loss was measured in groups brushed with toothpaste than in groups brushed with water. One-hour immersion in artificial saliva significantly reduced enamel loss when teeth were brushed with water (group 3; P < 0.05) but not with toothpaste (group 4). This study established a protocol for measuring enamel loss resulting from erosion followed by toothbrush abrasion. The results confirmed the abrasive action of toothpaste on acid-softened enamel.

Assembly and Characterization of Well Defined High Molecular Weight Poly(p-phenylene) Polymer Brushes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alonzo Calderon, Jose E; Kilbey, II, S Michael; Ankner, John Francis

2011-01-01

The assembly and characterization of well-defined, end-tethered poly(p-phenylene) (PPP) brushes having high molecular weight, low polydispersity and high 1,4-stereoregularity are presented. The PPP brushes are formed using a precursor route that relies on either self-assembly or spin coating of high molecular weight (degrees of polymerizations 54, 146, and 238) end-functionalized poly(1,3-cyclohexadiene) (PCHD) chains from benzene solutions onto silicon or quartz substrates, followed by aromatization of the end-attached PCHD chains on the surface. The approach allows the thickness (grafting density) of the brushes to be easily varied. The dry brushes before and after aromatization are characterized by ellipsometry, atomic force microscopy,more » grazing angle attenuated total reflectance Fourier transform infrared spectroscopy, and UV-Vis spectroscopy. The properties of the PPP brushes are compared with those of films made using oligo-paraphenylenes and with ab initio density functional theory simulations of optical properties. Our results suggest conversion to fully aromatized, end-tethered PPP polymer brushes having effective conjugation lengths of 5 phenyl units.« less

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

NASA Astrophysics Data System (ADS)

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

Early response of ponderosa pine to spacing and brush: observations on a 12-year-old plantation

Treesearch

William W. Oliver

1979-01-01

Ponderosa pine (Pinus ponderosa Laws.) was planted at five different spacings, from 6 by 6 to 18 by 18 feet, on a productive site in northern California. Spacing and brush effects on tree growth were evaluated both on plots where brush was allowed to develop and on plots kept free of brush. Competition between trees in brush-free plots began during...

The effect of brushing with toothpaste containing nano calcium carbonate upon nanofill composite resin surface roughness

NASA Astrophysics Data System (ADS)

Ramadhani, A. M.; Herda, E.; Triaminingsih, S.

2017-08-01

This study aims to determine the effect of brushing with toothpaste containing nanocalcium carbonate on the roughness of nanofill composite resin surface. Brushing was conducted with 3 types of materials for 3 consecutive brushing periods of 10 minutes each. Surface roughness was measured using a surface-roughness tester and the results were analyzed using the repeated ANOVA and the one-way ANOVA test. The surface morphology was observed using SEM after 3 months’ worth of brushing with the 3 materials. It was found that the nanofill composite resin surface-roughness value increased significantly (p<0.005) after brushing with toothpaste containing nano calcium carbonate for 3 months, but the value was not as high as that obtained when brushing with other types of toothpaste.

Evaluation of Brushing as a Lunar Dust Mitigation Strategy for Thermal Control Surfaces

NASA Technical Reports Server (NTRS)

Gaier, James R.; Journey, Khrissaundra; Christopher, Steven; Davis, Shanon

2011-01-01

Evaluation of brushing to remove lunar simulant dust from thermal control surfaces is described. First, strip brushes made with nylon, PTFE, or Thunderon (Nihon Sanmo Dyeing Company Ltd.) bristles were used to remove JSC-1AF dust from AZ93 thermal control paint or aluminized FEP (AlFEP) thermal control surface under ambient laboratory conditions. Nylon and PTFE bristles removed a promising amount of dust from AZ93, and nylon and Thunderon bristles from AlFEP. But when these were tested under simulated lunar conditions in the lunar dust adhesion bell jar (LDAB), they were not effective. In a third effort, seven brushes made up of three different materials, two different geometries, and different bristle lengths and thicknesses were tested under laboratory conditions against AZ93 and AlFEP. Two of these brushes, the Zephyr fiberglass fingerprint brush and the Escoda nylon fan brush, removed over 90 percent of the dust, and so were tested in the fourth effort in the LDAB. They also performed well under these conditions recovering 80 percent or more of the original thermal performance (solar absorptance/thermal emittance) of both AZ93 and AgFEP after 20 strokes, and 90 or more percent after 200 strokes

Evaluation of tablet PC as a tool for teaching tooth brushing to children.

PubMed

Salama, F; Abobakr, I; Al-Khodair, N; Al-Wakeel, M

2016-12-01

This study evaluated the effect of a single time tooth brushing instruction using video on a tablet PC (Apple iPad) compared to operator presentation using jaw model for plaque removal. This cross-sectional study included a convenience sample of 100 children divided into two groups. For Group 1 brushing was demonstrated to the child by the operator with the use of a jaw model. This demonstration was videotaped for subsequent use in Group 2 using a tablet PC (Apple iPad). Plaque index was recorded before and after demonstration of the assigned method of teaching tooth brushing. The results showed a significant difference using the two methods. The difference between the mean plaque index values with the jaw model and tablet PC at baseline and after tooth brushing represented 17.27% (50% improvement) and 11.56% (34% improvement) respectively. Boys showed a 18.3%. higher improvement in tooth brushing compared to girls. Seventy-five percent of the children reported using tablet computers in their daily life. CONCLUSION Teaching children by using a jaw model was more effective in improving plaque index score than using video on tablet PC by 16%. Both methods of tooth brushing teaching were fully accepted by all children.

Influence of cutting time on brush response: implications for herbivory in linear (transportation) corridors.

PubMed

Rea, Roy V; Child, Kenneth N; Spata, David P; MacDonald, Douglas

2007-08-01

An experiment was conducted to determine the influence the time of brush-cutting can have on plant regrowth and attractiveness to herbivores that browse in linear corridors. The influence of cutting time on leaf flush and senescence, shoot morphometry, and biomass was measured for 3 consecutive years after initial brush-cutting. Results indicate that morphological and phenological attributes of three woody deciduous plants were influenced by the timing of brush-cutting for up to 3 years after initial cutting. Brush-cutting generally stimulated plants to produce larger than normal shoots and delay leaf senescence. The degree to which plants were affected, however, varied with the timing of initial cutting and the species in question. Generally, plants cut later in the year resprouted more vigorously and were taller in the third year after cutting but produced less overall biomass than when cut earlier. In the years following brush-cutting, plants cut earlier flushed leaves earlier in the spring but delayed leaf senescence in the fall when compared to uncut controls. Results of these trials suggest that brush-cutting time influences plant response and several plant attributes known to influence plant attractiveness to moose and other herbivores. We therefore recommend that roadside and railside vegetation management plans consider the influence of cutting time on plant regrowth. Such considerations can ensure that brush is cut to reduce the attractiveness of plant regrowth in these linear corridors, reduce the utilization of such brush by herbivores, and, as such, mitigate collision risk between motorists and herbivores such as moose.

Polymer Brush-Functionalized Chitosan Hydrogels as Antifouling Implant Coatings.

PubMed

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.

DREW-UCLA Breast Cancer Research and Training Program: Molecular/Cellular Pathogenesis Model

DTIC Science & Technology

2007-03-01

system in bovine renal brush- border [13] and in a bovine renal epithelial cell line NBL -1 [14]. In order to highlight the substrate difference with an... NBL -1 expresses a broad specificity Na(+)-dependent neu- tral amino acid transport system (System B0) similar to that in bovine renal brush border

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

PubMed Central

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

In Vitro Assessment of the Abrasion Resistance of Two Types of Artificial Teeth Submitted to Brushing.

PubMed

Policastro, Vivian Barnabé; Giro, Gabriela; Leite, Andressa Rosa Perin; Mendoza-Marin, Danny Omar; Paleari, André Gustavo; Compagnoni, Marco Antonio; Pero, Ana Carolina

2016-08-01

To assess the effect of brushing with different solutions on the abrasion resistance of two types of acrylic resin teeth. Maxillary premolars from two types of acrylic teeth (Biotone and Biotone IPN) were divided into six groups (n = 12), according to the solution used during brushing: distilled water (control), coconut soap, or dentifrice. A mechanical brushing machine was used to simulate approximately 1 year of brushing (11,000 strokes). The weight loss (WL) of teeth was obtained from the difference between the initial (IW) and final weight (FW) of each specimen, and the mean of percentage of weight loss (PWL) was calculated for each group. Data were analyzed using the Kruskal-Wallis test, followed by Bonferroni's post-test comparison (α = 0.05). A statistically significant difference was found for the factor solution (p < 0.001). Brushing using dentifrice caused the highest values of weight loss (-0.50%), in comparison with the groups brushed with coconut soap (0.00%) or distilled water (0.00%). For both types of artificial teeth, brushing with dentifrice produced higher abrasion than brushing with coconut soap or water. © 2016 by the American College of Prosthodontists.

The efficacy of oral brush biopsy with computer-assisted analysis in identifying precancerous and cancerous lesions

PubMed Central

2011-01-01

Background Cancer of the oral cavity is the sixth most common malignancy reported worldwide and one with the highest mortality rate among all malignancies. There is a paucity of reliable diagnostic methods to detect early malignancies. This study was performed to evaluate the sensitivity and specificity of brush biopsy in identifying oral premalignant and malignant lesions. Methods Oral brush and scalpel biopsies were performed on 85 consecutive patients presenting with an oral lesion deemed to be minimally suspicious by clinical examination and the results were compared. Results Of 79 patients with adequate brush biopsy samples with matching scalpel biopsies, 27 revealed histopathologic evidence of dysplasia or carcinoma, 26 of which were independently identified with the oral brush biopsy (sensitivity: 96.3% - 95% CI, 87%-100%). 52 oral lesions did not reveal any histopathologic evidence of dysplasia or carcinoma and of these, brush biopsy reported 47 as "negative" and 5 as "atypical"(specificity of "positive" brush biopsy result is 100%- 95% CI, 93%-100%; specificity for "atypical" brush biopsy result is 90.4%- 95% CI, 82%-97%. The positive predictive value of an abnormal oral brush biopsy was 84% and the negative predictive value was 98%. Conclusion Our study demonstrated that the oral brush biopsy is an accurate test in identifying oral premalignant and malignant lesions, even if minimally suspicious. PMID:21864339

Fluoroscopic percutaneous brush cytology, forceps biopsy and both in tandem for diagnosis of malignant biliary obstruction.

PubMed

Boos, Johannes; Yoo, Raphael J; Steinkeler, Jennifer; Ayata, Gamze; Ahmed, Muneeb; Sarwar, Ammar; Weinstein, Jeffrey; Faintuch, Salomao; Brook, Olga R

2018-02-01

To evaluate percutaneous brush cytology, forceps biopsy and a tandem procedure consisting of both, in the diagnosis of malignant biliary obstruction. A retrospective review of consecutive patients who underwent biliary brush cytology and/or forceps biopsy between 01/2010 and 09/2014 was performed. The cytology and pathology results were compared to the composite outcome (including radiological, pathological and clinical data). Cost for tandem procedure compared to brush cytology and forceps biopsy alone was calculated. A total of 232 interventions in 129 patients (70.8 ± 11.0 years) were included. Composite outcome showed malignancy in 94/129 (72.9%) patients. Sensitivity for brush cytology, forceps biopsy and tandem procedure was 40.6% (95% CI 32.6-48.7%), 42.7% (32.4-53.0%) and 55.8% (44.7-66.9%) with 100% specificity, respectively. There were 9/43 (20.9%) additional cancers diagnosed when forceps biopsy was performed in addition to brush cytology, while there were 13/43 (30.2%) more cancers diagnosed when brush cytology was performed in addition to forceps biopsy. Additional costs per additionally diagnosed malignancy if tandem approach is to be utilised in all cases was $704.96. Using brush cytology and forceps biopsy in tandem improves sensitivity compared to brush cytology and forceps biopsy alone in the diagnosis of malignant biliary obstruction. • Tandem procedure improves sensitivity compared to brush cytology and forceps biopsy. • Brush cytology may help to overcome "crush artefacts" from forceps biopsy. • The cost per diagnosed malignancy may warrant tandem procedure in all patients.

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

PubMed Central

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

2014-01-01

Objective 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. Basic Research Design Secondary data analyses were conducted on two waves of data from the Aban Aya Youth Project and the Iowa Fluoride Study. Participants 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. Main Outcome Measures In both studies, reported daily tooth brushing frequency was assessed twice six months apart. Results 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. Conclusions 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. PMID:25300146

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

PubMed

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.

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

PubMed

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.

Segment density profiles of polyelectrolyte brushes determined by Fourier transform ellipsometry

NASA Astrophysics Data System (ADS)

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.

Toothbrush abrasivity in a long-term simulation on human dentin depends on brushing mode and bristle arrangement.

PubMed

Bizhang, Mozhgan; Schmidt, Ilka; Chun, Yong-Hee Patricia; Arnold, Wolfgang H; Zimmer, Stefan

2017-01-01

The aim of this study was to evaluate the susceptibility of dentin to brushing abrasion using four different toothbrushes (rotating-oscillating, sonic and two types of manual toothbrushes) with the same brushing forces. Dentin samples (n = 72) were selected from 72 impacted third molars. Half of the surface of dentin samples was covered with an adhesive tape, creating a protected and a freely exposed area in the same specimen. Brushing was performed with either a: sonic (Sonicare PowerUp, Philips GmbH, Hamburg, Germany), b: oscillating-rotating (Oral B Vitality Precisions Clean, Procter & Gamble, Schwalbach am Taunus, Germany) or two different manual toothbrushes c: flat trim brush head toothbrush (Dr. Best: Original, Glaxo-Smith-Kline, Bühl, Germany) and d: rippled-shaped brush head toothbrush (Blend-a-Dent, Complete V-Interdental, Blend-a-med, Schwalbach, Germany) in a custom made automatic brushing machine. The brushing force was set to 2 N and a whitening toothpaste (RDA = 150) was used. The simulation period was performed over a calculated period to mimic a brushing behavior of two times a day brushing for eight years and six months. Dentin loss was quantitatively determined by profilometry and statistically analyzed by Wilcoxon and Mann-Whitney-U Test (p < 0.05). The mean (standard deviation) surface loss was 21.03 (±1.26) μm for the sonic toothbrush, 15.71 (±0.85) μm for the oscillating-rotating toothbrush, 6.13 (±1.24) μm for the manual toothbrush with flat trim brush head and 2.50 (±0.43) μm for the manual toothbrush with rippled-shaped brush head. Differences between all groups were statistically significant at p<0.05. Using the same brushing force and a highly abrasive toothpaste, manual toothbrushes are significantly less abrasive compared to power toothbrushes for an 8.5-year simulation.

Friendship Network and Dental Brushing Behavior among Middle School Students: An Agent Based Modeling Approach.

PubMed

Sadeghipour, Maryam; Khoshnevisan, Mohammad Hossein; Jafari, Afshin; Shariatpanahi, Seyed Peyman

2017-01-01

By using a standard questionnaire, the level of dental brushing frequency was assessed among 201 adolescent female middle school students in Tehran. The initial assessment was repeated after 5 months, in order to observe the dynamics in dental health behavior level. Logistic Regression model was used to evaluate the correlation among individuals' dental health behavior in their social network. A significant correlation on dental brushing habits was detected among groups of friends. This correlation was further spread over the network within the 5 months period. Moreover, it was identified that the average brushing level was improved within the 5 months period. Given that there was a significant correlation between social network's nodes' in-degree value, and brushing level, it was suggested that the observed improvement was partially due to more popularity of individuals with better tooth brushing habit. Agent Based Modeling (ABM) was used to demonstrate the dynamics of dental brushing frequency within a sample of friendship network. Two models with static and dynamic assumptions for the network structure were proposed. The model with dynamic network structure successfully described the dynamics of dental health behavior. Based on this model, on average, every 43 weeks a student changes her brushing habit due to learning from her friends. Finally, three training scenarios were tested by these models in order to evaluate their effectiveness. When training more popular students, considerable improvement in total students' brushing frequency was demonstrated by simulation results.

A Low Cost Brush Deflection System for Bank Stabilization and Revegetation

Treesearch

Mary Elizabeth Meyer

1989-01-01

A series of brush deflectors were installed along an eroding, undercut streambank on Lindo Channel in Chico, California. Pieces of brush were wired to sets of metal fenceposts driven into the bank perpendicular to stream flow and at strategic points upstream. Dormant cuttings of riparian plants were added for revegetation and long-term bank protection. To date (two...

Structural analysis of paintings based on brush strokes

NASA Astrophysics Data System (ADS)

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.

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

NASA Astrophysics Data System (ADS)

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.

Tooth brushing frequency and risk of new carious lesions.

PubMed

Holmes, Richard D

2016-12-01

Data sourcesMedline, Embase, CINHAL and the Cochrane databases.Study selectionTwo reviewers selected studies, and case-control, prospective cohort, retrospective cohort and experimental trials evaluating the effect of toothbrushing frequency on the incidence or increment of new carious lesions were considered.Data extraction and synthesisTwo reviewers undertook data abstraction independently using pre-piloted forms. Study quality was assessed using a quality assessment tool for quantitative studies developed by the Effective Public Health Practice Project (EPHPP). Meta-analysis of caries outcomes was carried out using RefMan and meta-regressions undertaken to assess the influence of sample size, follow-up period, caries diagnosis level and study methodological quality.ResultsThirty-three studies were included of which 13 were considered to be methodologically strong, 14 moderate and six weak. Twenty-five studies contributed to the quantitative analysis. Compared with frequent brushers, self-reported infrequent brushers demonstrated a higher incidence of carious lesions, OR=1.50 (95%CI: 1.34 -1.69). The odds of having carious lesions differed little when subgroup analysis was conducted to compare the incidence between ≥2 times/d vs <2 times/d; OR=1.45; (95%CI; 1.21 - 1.74) and ≥1 time/d vs <1 time/d brushers OR=1.56; (95%CI; 1.37 - 1.78). Brushing <2 times/day significantly caused an increment of carious lesions compared with ≥2/day brushing, standardised mean difference [SMD] =0.34; (95%CI; 0.18 - 0.49). Overall, infrequent brushing was associated with an increment of carious lesions, SMD= 0.28; (95%CI; 0.13 - 0.44). Meta-analysis conducted with the type of dentition as subgroups found the effect of infrequent brushing on incidence and increment of carious lesions was higher in deciduous, OR=1.75; (95%CI; 1.49 - 2.06) than permanent dentition OR=1.39; (95% CI: 1.29 -1.49). Meta-regression indicated that none of the included variables influenced the effect

Comparison of the tooth brushing habits of primary school age children and their parents.

PubMed

Ozbek, Ceren Damla; Eser, Didem; Bektas-Kayhan, Kivanc; Unur, Meral

2015-01-01

As they grow, children develop their attitude and behavior related to tooth brushing by taking their parents' oral-dental health behavior as an example. The purpose of this study was to assess whether there was a similarity in tooth brushing between primary school-age children and their parents presenting to the Department of Oral, Dental and Jaw Diseases and Surgery and the Department of Pedodontics, School of Dental Medicine, Istanbul University. The study included 126 children and their parents, as totally 252 subjects. The data on oral hygiene of the subjects were obtained using a questionnaire form including questions on the qualitative-quantitative tooth brushing habits of the children and their parents and the socio-demographic characteristics of their families. In most of the cases, there was a similarity between children and their parents in terms of the frequency of dentist visits, the therapy they underwent in their last dentist visit, the cause of caries, the frequency of tooth brushing, the material used for oral hygiene, the duration of tooth brushing, method of tooth brushing, and tooth sites most brushed, which showed a significant association between children and their parents (p<0.01). Correct knowledge given to the children by their families will positively affect the oral-dental health of the children. Thus, firstly, correct knowledge should be given to the parents so that they can successfully carry out their responsibility in being the correct model for their children in oral-dental health.

Eccentricity effects on leakage of a brush seal at low speeds

NASA Technical Reports Server (NTRS)

Schlumberger, Julie A.; Proctor, Margaret P.; Hendricks, Robert C.

1991-01-01

The effects of eccentricity on brush seal leakage at low rotational speeds were investigated. Included are the leakage results for ambient temperature air and nearly saturated streams at three different rotor eccentricities at both 0 and 400 rpm. A brush seal with a nominal bore diameter of 13.647 cm. (5.3730 in.) was used. It had a radial concentric interference of 0.071 cm (0.0028 in.) and a fence height of 0.0927 cm (0.0365 in.). There were 1060 bristles per centimeter of circumference (2690 bristles per inch of circumference). Rotor eccentricities of 0.003, 0.010, 0.038, and 0.043 cm (0.001, 0.004, 0.015, and 0.017 in.) were achieved by using bushings with different offsets. The results were compared with an annular seal model (FLOWCAL) for air and to a standard labyrinth seal model for steam. The annular seal model was also compared with a bulk flow model of a concentric brush seal in air. Large eccentricities did not damage the brush seals or their Haynes 25 bristles. However, the 304 stainless steel rotor did not show wear, indicating a harder surface is needed. Only the stream data showed hysteresis and were affected by shaft rotation. The brush seal had lower leakage rates than those predicted for comparable annular and labyrinth seals (conventional) because of the large clearances those seals require to accommodate large shaft excursions.

Vertical Phase Segregation Induced by Dipolar Interactions in Planar Polymer Brushes

DOE PAGES

Mahalik, Jyoti P.; Sumpter, Bobby G.; Kumar, Rajeev

2016-09-13

In this paper, we present a generalized theory for studying structural properties of a planar dipolar polymer brush immersed in a polar solvent. We show that an explicit treatment of the dipolar interactions yields a macroscopic concentration dependent effective “chi” (the Flory–Huggins-like interaction) parameter. Furthermore, it is shown that the concentration dependent chi parameter promotes phase segregation in polymer solutions and brushes so that the polymer-poor phase consists of a finite/nonzero polymer concentration. Such a destabilization of the homogeneous phase by the dipolar interactions appears as vertical phase segregation in a planar polymer brush. In a vertically phase segregated polymermore » brush, the polymer-rich phase near the grafting surface coexists with the polymer-poor phase at the other end. Predictions of the theory are directly compared with prior reported experimental results for dipolar polymers in polar solvents. Excellent agreements with the experimental results are found, hinting that the dipolar interactions play a significant role in vertical phase segregation of planar polymer brushes. We also compare our field theoretical approach with the two-state and other models invoking ad hoc concentration dependence of the chi parameter. Interplay between the short-ranged excluded volume interactions and long-ranged dipolar interactions is shown to play an important role in affecting the vertical phase separation. Finally, effects of mismatch between the dipole moments of the polymer segments and the solvent molecules are investigated in detail.« less

Brush Seal Performance and Durability Issues Based on T-700 Engine Test Results

NASA Technical Reports Server (NTRS)

Hendricks, R. C.

1994-01-01

The integrity and performance of brush seals have been established. Severe bench and engine tests have shown high initial wear or run-in rates, material smearing at the interface, and bristle and rub-runner wear, but the brush seals did not fail. Short-duration (46 hr) experimental T-700 engine testing of the compressor discharge seal established over 1-percent engine performance gain (brush versus labyrinth). Long-term gains were established only as leakage comparisons, with the brush at least 20 percent better at controlling leakage. Long-term materials issues, such as wear and ultimately seal life, remain to be resolved. Future needs are cited for materials and analysis tools that account for heat generation, thermomechanical behavior, and tribological pairing to enable original equipment manufacturers to design high-temperature, high-surface-speed seals with confidence.

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

PubMed

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.

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

NASA Astrophysics Data System (ADS)

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.

Nanoscale evaluation of lubricity on well-defined polymer brush surfaces using QCM-D and AFM.

PubMed

Kitano, Kazuhiko; Inoue, Yuuki; Matsuno, Ryosuke; Takai, Madoka; Ishihara, Kazuhiko

2009-11-01

For preparing a "highly lubricated biointerface", which has both excellent lubricity and biocompatibility, we investigated the factors responsible for resistance to friction during polymer grafting. We prepared poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), poly(2-hydroxyethyl methacrylate) (PHEMA), and poly(methyl methacrylate) (PMMA) brush layers with high graft density and well-controlled thickness using atom transfer radical polymerization (ATRP). We measured the water absorptivity in the polymer brush layers and the viscoelasticity of the polymer-hydrated layers using a quartz crystal microbalance with dissipation monitoring (QCM-D) measurements. The PMPC brush layer had the highest water absorptivity, while the PMPC-hydrated layer had the highest fluidity. The friction properties of the polymer brush layers were determined in air, water, and toluene by atomic force microscopy (AFM). The friction on each polymer brush decreased only when a good solvent was chosen for each polymer. In conclusion, the brush layer possessing high water absorptivity and fluidity in water contributes to reduce friction. PMPC grafting is an effective and promising method for obtaining highly lubricated biointerfaces.

Covariates of Tooth-brushing Frequency in Low-income African Americans From Grades 5 to 8

PubMed Central

Koerber, A.; Graumlich, S.; Punwani, I.C.; Berbaum, M.L.; Burns, J.L.; Levy, S.R.; Cowell, J.M.; Flay, B.R.

2009-01-01

Purpose The purpose of this study was to examine tooth-brushing frequency in 575 urban and nearby suburban African American children as part of a comprehensive risk-reduction study for students at high risk for violence, drugs, school delinquency, and unsafe sexual behaviors to determine which covariates predicted tooth-brushing frequency. Methods Students were surveyed 5 times, from the beginning of grade 5 and the end of each year through grade 8, and parents were surveyed at the beginning of grade 5. Peer influence, importance of being liked, self-esteem, attitudes towards tooth-brushing, oral health knowledge, self-efficacy, parental attitudes, and other covariates were examined for the ability to predict self-reporting of tooth-brushing frequency. Results In the fifth grade, peer influence, the importance of being liked, and physical self-esteem were the significant predictors, and peer influence continued to predict tooth-brushing in the eighth grade. Oral health knowledge and parental influence were not significant. Conclusion Peer influence is an important factor in tooth-brushing behavior in metropolitan African American preadolescent children. PMID:17249434

Covariates of tooth-brushing frequency in low-income African Americans from grades 5 to 8.

PubMed

Koerber, A; Graumlich, S; Punwani, I C; Berbaum, M L; Burns, J L; Levy, S R; Cowell, J M; Flay, B R

2006-01-01

The purpose of this study was to examine tooth-brushing frequency in 575 urban and nearby suburban African American children as part of a comprehensive risk-reduction study for students at high risk for violence, drugs, school delinquency, and unsafe sexual behaviors to determine which covariates predicted tooth-brushing frequency. Students were surveyed 5 times, from the beginning of grade 5 and the end of each year through grade 8, and parents were surveyed at the beginning of grade 5. Peer influence, importance of being liked, self-esteem, attitudes towards tooth-brushing, oral health knowledge, self-efficacy, parental attitudes, and other covariates were examined for the ability to predict self-reporting of tooth-brushing frequency. In the fifth grade, peer influence, the importance of being liked, and physical self-esteem were the significant predictors, and peer influence continued to predict tooth-brushing in the eighth grade. Oral health knowledge and parental influence were not significant. Peer influence is an important factor in tooth-brushing behavior in metropolitan African American preadolescent children.

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

PubMed

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.

21 CFR 884.1100 - Endometrial brush.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 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...

21 CFR 884.1100 - Endometrial brush.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 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...

21 CFR 884.1100 - Endometrial brush.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 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...

Frequency of tooth brushing and associated factors in Mexican schoolchildren six to nine years of age.

PubMed

Casanova-Rosado, J F; Vallejos-Sánchez, A A; Minaya-Sánchez, M; Medina-Solís, C E; De La Rosa-Santillana, R; Márquez-Corona, M de L; Maupomé, G

2013-01-01

To determine the prevalence of daily tooth brushing and evaluate some variables associated. A cross-sectional study was carried out in 320 schoolchildren six to nine years old in Campeche, Mexico. Information on sociodemographic and socio-economic variables, oral hygiene practices and attitudes were collected through a questionnaire. The frequency of tooth brushing was categorized as "0" = fewer than seven times/week, "1" = at least once a day. In the analysis, nonparametric tests were used. Mean age was 6.99 +/- 1.00 years, 52.5% were boys. The prevalence of daily tooth brushing was 81.6%. In bivariate analysis, the prevalence of tooth brushing was higher (p < 0.05) among the children of mothers with higher schooling (9.80 years vs 8.47 years, p < 0.05), and in younger children (84.6% in 6-7-year olds vs 71.2% in 8-9-year olds, p < 0.05). A slight, non-significant association (p < 0.10) was noted between the current frequency of tooth brushing and an earlier age when the child first started brushing with toothpaste. There were no statistically significant differences (p > 0.05) in the frequency of tooth brushing by gender or by the mother's attitude toward the oral health of her child. The prevalence of daily tooth brushing was high compared to other studies. Mother's maximum level of schooling (as an indicator of socio-economic position) was associated with higher frequency of tooth brushing. Maternal characteristics are associated with the oral health behaviour of their children.

Parental Attitudes and Tooth Brushing Habits in Preschool Children in Mangalore, Karnataka: A Cross-sectional Study.

PubMed

Pullishery, Fawaz; Shenoy Panchmal, Ganesh; Shenoy, Rekha

2013-09-01

Adoption of consistent behavioral habits in childhood takes place at home, with the parents especially the mother, being the primary model for behavior. Tooth brushing habits which is learnt during early years of life, is deeply ingrained in the child's mind and it is expected that this leads to an adaptation of good oral hygiene in their later life. To assess the tooth brushing habits of preschool children and to determine the role and amount of supervision given to them by parents. A pretested self-designed questionnaire was used to collect information from parents of 130 preschool children in Anganwadi and Kindergarten in Mangalore. Statistical analysis was done and Chi-square test was used. Tooth brushing habits in these children was started at a mean age of 22.4 months (SD 8.4).62% of the preschool children used toothbrush and toothpaste for cleaning teeth and brushing habits were mainly (84%) introduced by mothers. Seventy-one percent of the children were cooperative when they were introduced to tooth brushing. Preschool children of Mangalore were introduced to tooth brushing at a mean age of 22.4 months. Mothers played a vital role in introducing and teaching the child how to brush. In children less than 10 months of age tooth brushing was not started at all. How to cite this article: Pullishery F, Panchmal GS, Shenoy R. Parental Attitudes and Tooth Brushing Habits in Preschool Children in Mangalore, Karnataka: A Cross-sectional Study. Int J Clin Pediatr Dent 2013;6(3):156-160.

Parental Attitudes and Tooth Brushing Habits in Preschool Children in Mangalore, Karnataka: A Cross-sectional Study

PubMed Central

Shenoy Panchmal, Ganesh; Shenoy, Rekha

2013-01-01

ABSTRACT Background: Adoption of consistent behavioral habits in childhood takes place at home, with the parents especially the mother, being the primary model for behavior. Tooth brushing habits which is learnt during early years of life, is deeply ingrained in the child's mind and it is expected that this leads to an adaptation of good oral hygiene in their later life. Objectives: To assess the tooth brushing habits of preschool children and to determine the role and amount of supervision given to them by parents. Study design: A pretested self-designed questionnaire was used to collect information from parents of 130 preschool children in Anganwadi and Kindergarten in Mangalore. Statistical analysis was done and Chi-square test was used. Results: Tooth brushing habits in these children was started at a mean age of 22.4 months (SD 8.4).62% of the preschool children used toothbrush and toothpaste for cleaning teeth and brushing habits were mainly (84%) introduced by mothers. Seventy-one percent of the children were cooperative when they were introduced to tooth brushing. Conclusion: Preschool children of Mangalore were introduced to tooth brushing at a mean age of 22.4 months. Mothers played a vital role in introducing and teaching the child how to brush. In children less than 10 months of age tooth brushing was not started at all. How to cite this article: Pullishery F, Panchmal GS, Shenoy R. Parental Attitudes and Tooth Brushing Habits in Preschool Children in Mangalore, Karnataka: A Cross-sectional Study. Int J Clin Pediatr Dent 2013;6(3):156-160. PMID:25206214

Use of a disclosed plaque visualization technique improved the self-performed, tooth brushing ability of primary schoolchildren.

PubMed

Chounchaisithi, Napa; Santiwong, Busayarat; Sutthavong, Sirikarn; Asvanit, Pompun

2014-02-01

Disclosing agents have a long history of use as an aid in children's tooth brushing instruction. However, their benefit when used to improve self-performed tooth brushing ability without any tooth brushing instruction has not been investigated. To evaluate the effect of disclosed plaque visualization on improving the self-performed, tooth brushing ability of primary school children. A cluster-randomized, crossover study was conducted in Nakhon Nayok province, Thailand. A total of 122 second-grade schoolchildren, aged 8-10 years old, from 12 schools were randomly divided into 2 groups. The first group was assigned to brush with disclosed plaque visualization, while the other group brushed without disclosed plaque visualization. One month later the groups switched procedures. Tooth brushing ability was evaluated by the subjects' reduction in patient hygiene performance (PHP) scores. The data were analyzed using repeated-measures analysis of variance, with significance set at p<0.05. Disclosed plaque visualization had a significant effect on improving the children's self-performed, tooth brushing ability in all areas of the mouth (p<0.001), particularly for anterior teeth, mandibular teeth, buccal surfaces, and areas adjacent to the gingival margin (p<0.001). Disclosed plaque visualization is a viable technique to improve children's self-performed tooth brushing ability, and could be used in school-based oral health promotion programs.

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

PubMed Central

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

Toothbrush abrasivity in a long-term simulation on human dentin depends on brushing mode and bristle arrangement

PubMed Central

2017-01-01

Objective The aim of this study was to evaluate the susceptibility of dentin to brushing abrasion using four different toothbrushes (rotating-oscillating, sonic and two types of manual toothbrushes) with the same brushing forces. Methods Dentin samples (n = 72) were selected from 72 impacted third molars. Half of the surface of dentin samples was covered with an adhesive tape, creating a protected and a freely exposed area in the same specimen. Brushing was performed with either a: sonic (Sonicare PowerUp, Philips GmbH, Hamburg, Germany), b: oscillating-rotating (Oral B Vitality Precisions Clean, Procter & Gamble, Schwalbach am Taunus, Germany) or two different manual toothbrushes c: flat trim brush head toothbrush (Dr. Best: Original, Glaxo-Smith-Kline, Bühl, Germany) and d: rippled-shaped brush head toothbrush (Blend-a-Dent, Complete V-Interdental, Blend-a-med, Schwalbach, Germany) in a custom made automatic brushing machine. The brushing force was set to 2 N and a whitening toothpaste (RDA = 150) was used. The simulation period was performed over a calculated period to mimic a brushing behavior of two times a day brushing for eight years and six months. Dentin loss was quantitatively determined by profilometry and statistically analyzed by Wilcoxon and Mann-Whitney-U Test (p < 0.05). Results The mean (standard deviation) surface loss was 21.03 (±1.26) μm for the sonic toothbrush, 15.71 (±0.85) μm for the oscillating-rotating toothbrush, 6.13 (±1.24) μm for the manual toothbrush with flat trim brush head and 2.50 (±0.43) μm for the manual toothbrush with rippled-shaped brush head. Differences between all groups were statistically significant at p<0.05. Conclusion Using the same brushing force and a highly abrasive toothpaste, manual toothbrushes are significantly less abrasive compared to power toothbrushes for an 8.5—year simulation. PMID:28222156

Single molecule spectroscopy reveals heterogeneous transport mechanisms for molecular ions in a polyelectrolyte polymer brush.

PubMed

Reznik, Carmen; Estillore, Nicel; Advincula, Rigoberto C; Landes, Christy F

2009-11-05

Single molecule polarization and fluorescence correlation spectroscopy were used to evaluate heterogeneous transport mechanisms of molecular ions within supported polyelectrolyte brushes. Modes of diffusive transport include periods of significantly restricted rotational motion, often maintained over tens of milliseconds; periods of fast molecular rotation; and occasional adsorption of fluorescent probe molecules in the brush. The studies reveal rapid switching between orientational states during each observed mode of motion. Through quantitative analysis of state occupation times, the rate constants for transitions from weakly associated to strongly associated states were extracted. Additionally, the pH dependence of the ion transport rates in the brush exhibits an abrupt, rather than continuous, trend. These single molecule studies demonstrate the presence of dynamic anisotropic interactions between the charged molecular probe and the polymer brush and provide experimental evidence of stimuli responsive switchable transport functionality in the polyelectrolyte brush.

Isolation of the Lateral Border Recycling Compartment using a diaminobenzidine-induced density shift

PubMed Central

Sullivan, David P.; Rüffer, Claas; Muller, William A.

2014-01-01

The migration of leukocytes across the endothelium and into tissue is critical to mounting an inflammatory response. The Lateral Border Recycling Compartment (LBRC), a complex vesicular-tubule invagination of the plasma membrane found at endothelial cell borders, plays an important role in the this process. Although a few proteins have been shown to be present in the LBRC, no unique marker is known. Here we detail methods that can be used to characterize a subcellular compartment that lacks an identifying marker. Initial characterization of the LBRC was performed using standard subcellular fractionation with sucrose gradients and took advantage of the observation that the compartment migrated at a lower density than other membrane compartments. To isolate larger quantities of the compartment, we modified a classic technique known as a diaminobenzidine (DAB)-induced density shift. The DAB-induced density shift allowed for specific isolation of membranes labeled with HRP conjugated antibody. Because the LBRC could be differentially labeled at 4°C and 37°C, we were able to identify proteins that are enriched in the compartment, despite lacking a unique marker. These methods serve as a model to others studying poorly characterized compartments and organelles and are applicable to a wide variety of biological systems. PMID:24915828

Experimental and theoretical rotordynamic stiffness coefficients for a three-stage brush seal

NASA Astrophysics Data System (ADS)

Pugachev, A. O.; Deckner, M.

2012-08-01

Experimental and theoretical results are presented for a multistage brush seal. Experimental stiffness is obtained from integrating circumferential pressure distribution measured in seal cavities. A CFD analysis is used to predict seal performance. Bristle packs are modeled by the porous medium approach. Leakage is predicted well by the CFD method. Theoretical stiffness coefficients are in reasonable agreement with the measurements. Experimental results are also compared with a three-teeth-on-stator labyrinth seal. The multistage brush seal gives about 60% leakage reduction over the labyrinth seal. Rotordynamic stiffness coefficients are also improved: the brush seal has positive direct stiffness and smaller cross-coupled stiffness.

Polymer Brushes Containing Sulfonated Sugar Repeat Units: Synthesis, Characterization and In Vitro Testing of Blood Coagulation Activation

PubMed Central

Ayres, N.; Holt, D. J.; Jones, C.F.; Corum, L. E.; Grainger, D. W.

2009-01-01

A new polymer brush chemistry containing sulfonated carbohydrate repeat units has been synthesized from silicon substrates using ATRP methods and characterized both in bulk and using surface analysis. The polymer brush was designed to act as a mimic for the naturally occurring sulfonated glycosaminoglycan, heparin, commonly used for modifying blood-contacting surfaces both in vitro and in vivo. Surface analysis showed conversion of brush saccharide precursor chemistry to the desired sulfonated polymer product. The sulfonated polymer brush surface was further analyzed using three conventional in vitro tests for blood compatibility -- plasma recalcification times, complement activation, and thrombin generation. The sulfonated polymer brush films on silicon oxide wafers exhibited better assay performance in these blood component assays than the unsulfonated sugar functionalized polymer brush in all tests performed. PMID:19859552

A 12-week clinical comparison of an oscillating-rotating power brush versus a marketed sonic brush with self-adjusting technology in reducing plaque and gingivitis.

PubMed

Klukowska, Malgorzata; Grender, Julie M; Conde, Erinn; Goyal, C Ram

2013-01-01

The aim of this investigation was to assess the comparative gingivitis and plaque reduction efficacy of a leading oscillating-rotating power toothbrush and a recently introduced sonic toothbrush in adults with gingivitis. This was a 12-week, randomized and controlled, parallel group, examiner-blind, single-center clinical study of 130 adults with pre-existing gingivitis and plaque. At baseline, the Modified Gingival Index (MGI), Gingival Bleeding Index (GBI), and total number of bleeding sites were assessed, along with plaque levels (whole mouth, gingival margin, and interproximal) via the Rustogi Modified Navy Plaque Index (RMNPI). Qualified subjects were randomly assigned to one of two power toothbrush test groups: the Oral-B Triumph with SmartGuide (marketed in the United States as the Oral-B Professional Care SmartSeries 5000 [D34]) oscillating-rotating brush, or the Colgate ProClinical A1500 (also marketed as elmex ProClinical) sonic brush. Subjects brushed at home for two minutes twice daily with their assigned power toothbrush and a marketed sodium fluoride dentifrice, and were reevaluated for gingivitis at Week 4 and Week 12 via the MGI, GBI, and total number of bleeding sites, and for plaque reduction via the RMNPI. Ninety-seven percent (97%) of the 130 enrolled subjects completed the trial and 62 and 65 subjects in the oscillating-rotating and sonic brush groups, respectively, had evaluable data for analysis. Statistically significant mean reductions in all three gingivitis parameters and plaque relative to baseline were seen at both Weeks 4 and 12 with unsupervised use of both test toothbrushes (p < 0.001). The oscillating-rotating power brush provided statistically significantly superior reductions compared to the sonic brush in mean adjusted MGI (31% and 29% at Weeks 4 and 12, respectively; p < 0.001), GBI (17% at Week 12; p = 0.047), and total number of bleeding sites (48% and 30% at Weeks 4 and 12, respectively; p = 0.002), and produced statistically

Chain Conformation of Phosphorycholine-based Zwitterionic Polymer Brushes in Aqueous Solutions

NASA Astrophysics Data System (ADS)

Mao, Jun; Yu, Jing; Lee, Sungsik; Yuan, Guangcui; Satija, Sushil; Chen, Wei; Tirrell, Matthew

Polyzwitterionic brushes are resistant to nonspecific accumulation of proteins and microorganisms, making them excellent candidates for antifouling applications. It is well-known that polyzwitterions exhibit the so-called antipolyelectrolyte effect: Polyzwitterionic brushes would adopt a collapsed conformation at a low ionic strength due to the electrostatic inter/intra-chain association; whereas at a high ionic strength, they would exhibit an extended conformation because the electrostatic inter/intra-chain dipole-dipole interaction is weakened. However, poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) is a unique member in polyzwitterionic families. Its ultrahigh affinity to water leads to no detectable shrinks in aqueous solutions even at low ionic strengths. In this study, we synthesized highly dense PMPC brushes via surface initiated radical polymerization and systematically investigate their conformational behaviors at solid-liquid interfaces in the presence of multivalent counterions, combining X-ray and neutron scattering and force measurements. We have demonstrated that despite no obvious changes of the entire lengths of extended PMPC brushes in aqueous solutions, the chain conformations including, but not limited to, polyzwitterion distribution and charge correlation, varied, dependent on salt types, ionic strengths and ion valences.

Evidence to Support Tooth Brushing in Critically Ill Patients

PubMed Central

Ames, Nancy J.

2012-01-01

Tooth brushing in critically ill patients has been advocated by many as a standard of care despite the limited evidence to support this practice. Attention has been focused on oral care as the evidence accumulates to support an association between the bacteria in the oral microbiome and those respiratory pathogens that cause pneumonia. It is plausible to assume that respiratory pathogens originating in the oral cavity are aspirated into the lungs, causing infection. A recent study of the effects of a powered toothbrush on the incidence of ventilator-associated pneumonia was stopped early because of a lack of effect in the treatment group. This review summarizes the evidence that supports the effectiveness of tooth brushing in critically ill adults and children receiving mechanical ventilation. Possible reasons for the lack of benefit of tooth brushing demonstrated in clinical trials are discussed. Recommendations for future trials in critically ill patients are suggested. With increased emphasis being placed on oral care, the evidence that supports this intervention must be evaluated carefully. PMID:21532045

Evidence to support tooth brushing in critically ill patients.

PubMed

Ames, Nancy J

2011-05-01

Tooth brushing in critically ill patients has been advocated by many as a standard of care despite the limited evidence to support this practice. Attention has been focused on oral care as the evidence accumulates to support an association between the bacteria in the oral microbiome and those respiratory pathogens that cause pneumonia. It is plausible to assume that respiratory pathogens originating in the oral cavity are aspirated into the lungs, causing infection. A recent study of the effects of a powered toothbrush on the incidence of ventilator-associated pneumonia was stopped early because of a lack of effect in the treatment group. This review summarizes the evidence that supports the effectiveness of tooth brushing in critically ill adults and children receiving mechanical ventilation. Possible reasons for the lack of benefit of tooth brushing demonstrated in clinical trials are discussed. Recommendations for future trials in critically ill patients are suggested. With increased emphasis being placed on oral care, the evidence that supports this intervention must be evaluated carefully.

Interproximal plaque mass and fluoride retention after brushing and flossing--a comparative study of powered toothbrushing, manual toothbrushing and flossing.

PubMed

Sjögren, Karin; Lundberg, Ann-Britt; Birkhed, Dowen; Dudgeon, Douglas J; Johnson, Matthew R

2004-01-01

To determine differences in interproximal plaque mass and fluoride retention with different modes of toothbrushing and flossing. Forty-seven subjects in good health used four treatments in a four-period, randomized, crossover design: 1) manual brushing only; 2) manual brushing and daily flossing; 3) electric brushing using a rotational oscillation toothbrush; and 4) electric brushing using a sonic toothbrush. Subjects used a standard sodium fluoride dentifrice during the eight-day experimental periods and a fluoride-free dentifrice during the seven-day washout periods between treatments. Interproximal plaque samples were taken on Day 1 and on Day 8, weighed, and analyzed for fluoride content. The amount of interproximal plaque was lowest with sonic brushing, which left 43-65% less plaque than all other treatments. Manual brushing and flossing yielded less plaque than manual brushing alone and rotational oscillation brushing. Differences were statistically significant (p < 0.05) for treatment; there was no time effect on plaque mass. For fluoride retention, at Day 1 sonic brushing gave at least 54% more fluoride in the interproximal plaque than all other treatments, which was significant. All treatments demonstrated a significant increase in fluoride concentration with time except manual brushing and flossing, which showed a significant decrease. At Day 8, the fluoride concentration was significantly higher for sonic brushing than for manual brushing or rotational oscillation brushing by over 40%, and all treatments exhibited significantly greater fluoride than the manual brushing and flossing combination. The mode of toothbrushing may impact the amount of plaque retained interproximally and its fluoride concentration.

Effects of herbicides on some important brush species in southwestern Oregon.

Treesearch

H. Gratkowski

1959-01-01

A series of screening tests were established during 1955 to determine the effects of six commercial and experimental herbicides on brush in southwestern Oregon. The herbicides were tested as foliage sprays on 13 of the most abundant species and varieties of brush on forest lands in this area. Low volatile esters of 2, 4-D and 2,4, 5-T proved to be the most effective...

Does tooth brushing influence the development and progression of non-inflammatory gingival recession? A systematic review.

PubMed

Rajapakse, P Sunethra; McCracken, Giles I; Gwynnett, Erika; Steen, Nick D; Guentsch, Arndt; Heasman, Peter A

2007-12-01

The aim of this systematic review was to produce the best available evidence and pool appropriate data to evaluate the effect of tooth brushing on the initiation and progression of non-inflammatory gingival recession. A protocol was developed a priori for the question: "Do factors associated with tooth brushing predict the development and progression of non-inflammatory gingival recession in adults?" The search covered six electronic databases between January 1966 and July 2005. Hand searching included searches of the Journal of Clinical Periodontology, Journal of Periodontal Research and the Journal of Periodontology. Bibliographies of narrative reviews, conference proceedings and relevant texts known to the authors were also searched. Inclusion of titles, abstracts and ultimately full texts was based on consensus between three reviewers. The full texts of 29 papers were read and 18 texts were eligible for inclusion. One abstract from EuroPerio 5 reported a randomized-controlled clinical trial [Level I evidence] in which the authors concluded that the toothbrushes significantly reduced recessions on buccal tooth surfaces over 18 months. Of the remaining 17 observational studies, two concluded that there appeared to be no relationship between tooth brushing frequency and gingival recession. Eight studies reported a positive association between tooth brushing frequency and recession. Other potential risk factors were duration of tooth brushing, brushing force, frequency of changing the toothbrush, brush (bristle) hardness and tooth brushing technique. None of the observational studies satisfied all the specified criteria for quality appraisal and a valid appraisal of the quality of the randomized-controlled trial was not possible. The data to support or refute the association between tooth brushing and gingival recession are inconclusive.

Construction of Hierarchical Fouling Resistance Surfaces onto Poly(vinylidene fluoride) Membranes for Combating Membrane Biofouling.

PubMed

Li, Xue; Hu, Xuefeng; Cai, Tao

2017-05-09

Owing to the highly hydrophobic nature, fluoropolymer membranes usually suffer from serious fouling problem, and therefore largely limited their practical applications. Also, the development of environmentally benign and nonreleasing antifouling coatings onto the inert fluoropolymer membranes remains a great challenge and is of prime importance for various scientific interests and industrial applications. In the present work, a facile and effective approach for the construction of hierarchical fouling resistance surfaces onto the poly(vinylidene fluoride) (PVDF) membranes was developed. Graft copolymers of PVDF with poly(hyperbranched polyglycerol methacrylamide) side chains (PVDF-g-PHPGMA copolymers) were synthesized via reversible addition-fragmentation chain transfer (RAFT) graft copolymerization of pentafluorophenyl methacrylate (PFMA) with the ozone-preactivated PVDF, followed by activated ester-amine reaction of PPFMA chains with amino-terminated hyperbranched polyglycerol (HPG-NH 2 ). The copolymers could be simply processed into microfiltration (MF) membranes with surface-tethered PHPGMA side chains on the membrane and pore surfaces by nonsolvent induced phase inversion. Furthermore, the PVDF-g-PHPGMA-g-PSBMA membrane was prepared via surface-initiated atom transfer radical polymerization (SI-ATRP) of zwitterionic monomer, N-(3-sulfopropyl)-N-(methacryloxyethyl)-N,N-dimethylammonium betaine (SBMA) from the PVDF-g-PHPGMA membrane and pore surfaces. Arise from a synergistic effect of the dendritic architecture of PHPGMA branches and "superhydrophilic" nature of PSBMA brushes, the PVDF-g-PHPGMA-g-PSBMA membranes exhibit superior resistance to protein and bacteria adhesion with insignificant cytotoxicity effects, making the membranes potentially useful for water treatment and biomedical applications. One may find the present study a general and effective method for the fabrication of antifouling fluoropolymer membranes in a controllable and green manner.

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

NASA Astrophysics Data System (ADS)

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

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.

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

NASA Astrophysics Data System (ADS)

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

Metabolic stability of some tachykinin analogues to cell-surface peptidases: roles for endopeptidase-24.11 and aminopeptidase N.

PubMed

Medeiros, M D; Turner, A J

1995-01-01

The metabolism of several tachykinin antagonists by membrane peptidases has been examined. [beta Ala8]NKA(4-10) was not stabilized against degradation by endopeptidase-24.11 and this was the major activity in renal brush border membranes hydrolyzing this peptide. The antagonist MEN 10263 was much more resistant to hydrolysis by endopeptidase-24.11, although hydrolysis of the C-terminal Leu-Phe bond was detectable. Three other tachykinin receptor antagonists (MEN 10208, MEN 10207, and MEN 10376), by virtue of D-Trp substitutions, were rendered resistant to endopeptidase-24.11 but were still susceptible to aminopeptidase action. These studies provide further insight into design features necessary to produce metabolically stable peptide analogues.

Schoolchildren's tooth brushing characteristics and oral hygiene habits assessed with video-recorded sessions at school and a questionnaire.

PubMed

Martignon, Stefania; González, María Clara; Tellez, Marisol; Guzmán, Adriana; Quintero, Ingrid K; Sáenz, Viviana; Martínez, Miguel; Mora, Angelica; Espinosa, Luis Fernando; Castiblanco, Gina A

2012-01-01

Tooth brushing habits become established during the first years of childhood and last throughout lifetime. To assess tooth-brushing characteristics, the procedure was videotaped at school and a questionnaire on oral hygiene knowledge, attitudes and practices was completed. A total 146 5- to 8-year-old low-SES schoolchildren from Bogotá participated. The median total tooth brushing time was 115 sec (75% Q3-178 sec; 25% Q1-83 sec). The median time the toothbrush was in the child's mouth was 89 sec (75% Q3-145 sec; 25% Q1-65 sec). Most children brushed their maxillary (97%), mandibular (95%), anterior (96%) and posterior (81%) teeth. The surfaces most often brushed were the buccal-anterior-maxillary (96%) and mandibular (94%) surfaces. The amount of toothpaste dispensed was 2/3 of toothbrush head in 51% of children. Most children spat (93%), used the mirror (78%), and rinsed their mouth (72%). The majority (97%) was confident that the toothbrushing session was effective. The questionnaire revealed the following: none of the children brush their teeth at school; only 34% is supervised by an adult during the tooth brushing procedure, and only 30% brush twice a day. The study shows overall positive findings of tooth brushing while being observed, in terms of time and use of toothpaste. These results, together with the poor oral-health status and toothbrushing habits reported at home, highly recommend incorporating daily-supervised school-based tooth brushing sessions with fluoride toothpaste.

Assembly and Characterization ofWell-DefinedHigh-Molecular-Weight Poly(p-phenylene) Polymer Brushes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Jihua; Dadmun, Mark D; Mays, Jimmy

2011-01-01

The assembly and characterization of well-de ned, end-tethered poly- (p-phenylene) (PPP) brushes having high molecular weight, low polydispersity and high 1,4-stereoregularity are presented. The PPP brushes are formed using a precursor route that relies on either self-assembly or spin coating of high molecular weight (degrees of poly- merizations 54, 146, and 238) end-functionalized poly(1,3-cyclohexadiene) (PCHD) chains from benzene solutions onto silicon or quartz substrates, followed by aromatization of the end-attached PCHD chains on the surface. The approach allows the thickness (grafting density) of the brushes to be easily varied. The dry brushes before and after aromatization are characterized by ellipsometry,more » atomic force microscopy, grazing angle attenuated total re ectance Fourier transform infrared spectroscopy, and UV-Vis spectros- copy. The properties of the PPP brushes are compared with those of lms made using oligo- paraphenylenes and with ab initio density functional theory simulations of optical proper- ties. Our results suggest conversion to fully aromatized, end-tetheredPPPpolymerbrusheshaving eective conjugation lengths of 5 phenyl units.« less

U.S.-MEXICO BORDER PROGRAM ARIZONA BORDER STUDY

EPA Science Inventory

The Arizona Border Study, which measured levels of metals, pesticides, polynuclear aromatic hydrocarbons (PAHs), and volatile organic compounds (VOCs) in the Arizona counties bordering Mexico, is an extension of the Arizona National Human Exposure Assessment Survey (NHEXAS) Phase...

Disrupted apical exocytosis of cargo vesicles causes enteropathy in FHL5 patients with Munc18-2 mutations.

PubMed

Vogel, Georg F; van Rijn, Jorik M; Krainer, Iris M; Janecke, Andreas R; Posovszky, Carsten; Cohen, Marta; Searle, Claire; Jantchou, Prevost; Escher, Johanna C; Patey, Natalie; Cutz, Ernest; Müller, Thomas; Middendorp, Sabine; Hess, Michael W; Huber, Lukas A

2017-07-20

Familial hemophagocytic lymphohistiocytosis 5 (FHL5) is an autosomal recessive disease caused by mutations in STXBP2, coding for Munc18-2, which is required for SNARE-mediated membrane fusion. FHL5 causes hematologic and gastrointestinal symptoms characterized by chronic enteropathy that is reminiscent of microvillus inclusion disease (MVID). However, the molecular pathophysiology of FHL5-associated diarrhea is poorly understood. Five FHL5 patients, including four previously unreported patients, were studied. Morphology of duodenal sections was analyzed by electron and fluorescence microscopy. Small intestinal enterocytes and organoid-derived monolayers displayed the subcellular characteristics of MVID. For the analyses of Munc18-2-dependent SNARE-protein interactions, a Munc18-2 CaCo2-KO model cell line was generated by applying CRISPR/Cas9 technology. Munc18-2 is required for Slp4a/Stx3 interaction in fusion of cargo vesicles with the apical plasma membrane. Cargo trafficking was investigated in patient biopsies, patient-derived organoids, and the genome-edited model cell line. Loss of Munc18-2 selectively disrupts trafficking of certain apical brush-border proteins (NHE3 and GLUT5), while transport of DPPIV remained unaffected. Here, we describe the molecular mechanism how the loss of function of Munc18-2 leads to cargo-selective mislocalization of brush-border components and a subapical accumulation of cargo vesicles, as it is known from the loss of polarity phenotype in MVID.

Protein-Linked Glycan Degradation in Infants Fed Human Milk

PubMed Central

Dallas, David C.; Sela, David; Underwood, Mark A.; German, J. Bruce; Lebrilla, Carlito

2014-01-01

Many human milk proteins are glycosylated. Glycosylation is important in protecting bioactive proteins and peptide fragments from digestion. Protein-linked glycans have a variety of functions; however, there is a paucity of information on protein-linked glycan degradation in either the infant or the adult digestive system. Human digestive enzymes can break down dietary disaccharides and starches, but most of the digestive enzymes required for complex protein-linked glycan degradation are absent from both human digestive secretions and the external brush border membrane of the intestinal lining. Indeed, complex carbohydrates remain intact throughout their transit through the stomach and small intestine, and are undegraded by in vitro incubation with either adult pancreatic secretions or intact intestinal brush border membranes. Human gastrointestinal bacteria, however, produce a wide variety of glycosidases with regio- and anomeric specificities matching those of protein-linked glycan structures. These bacteria degrade a wide array of complex carbohydrates including various protein-linked glycans. That bacteria possess glycan degradation capabilities, whereas the human digestive system, perse, does not, suggests that most dietary protein-linked glycan breakdown will be of bacterial origin. In addition to providing a food source for specific bacteria in the colon, protein-linked glycans from human milk may act as decoys for pathogenic bacteria to prevent invasion and infection of the host. The composition of the intestinal microbiome may be particularly important in the most vulnerable humans-the elderly, the immunocompromised, and infants (particularly premature infants). PMID:24533224

Interspace/interdental brushes for oral hygiene in orthodontic patients with fixed appliances.

PubMed

Goh, H H

2007-07-18

Accumulation of plaque on tooth surfaces that have fixed orthodontic appliances is increased. Effective removal is essential to maintain oral health but it is unclear whether the use of interdental or interspace brushes is useful. To compare the effectiveness of standard toothbrushes with combined standard toothbrushes and interdental/interspace brushes used by patients during fixed orthodontic appliances therapy in relation to plaque removal, the health of dental and supporting tissues, dependability, cost and adverse effects. We searched the Cochrane Oral Health Group's Trials Register, CENTRAL, MEDLINE, EMBASE and CINAHL. Schools of dental hygiene were contacted for additional data. No language restrictions were applied. Handsearching of the relevant journals was carried out. Most recent search: January 2006. Randomised controlled trials (RCTs) including the following criteria: participants - patients with fixed orthodontic appliances and uncompromised manual dexterity; intervention - unsupervised toothbrushing with standard toothbrush alone versus standard toothbrush and interdental/interspace brush. Primary outcomes were differences in plaque control, gingival health and decalcification. Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were to be conducted in duplicate and independently. Trials were to be grouped in terms of their interventions and outcome measures. Results were to be expressed as random-effects models using standardised mean differences for continuous outcomes and risk ratios for dichotomous outcomes with 95% confidence intervals. Heterogeneity was to be investigated. No studies were identified to support or contest the null hypothesis. The present practice of recommending the use of interdental/interspace brushes in addition to standard toothbrushes is not supported by clinical investigations. Interdental brushes and normal toothbrushes wear is increased during orthodontic treatment

Poly(acrylic acid) brushes pattern as a 3D functional biosensor surface for microchips

NASA Astrophysics Data System (ADS)

Wang, Yan-Mei; Cui, Yi; Cheng, Zhi-Qiang; Song, Lu-Sheng; Wang, Zhi-You; Han, Bao-Hang; Zhu, Jin-Song

2013-02-01

Poly(acrylic acid) (PAA) brushes, a novel three dimensional (3D) precursor layer of biosensor or protein microarrays, possess high protein loading level and low non-specific protein adsorption. In this article, we describe a simple and convenient way to fabricate 3D PAA brushes pattern by microcontact printing (μCP) and characterize it with FT-IR and optical microscopy. The carboxyl groups of PAA brushes can be applied to covalently immobilize protein for immunoassay. Thriving 3D space made by patterning PAA brushes thin film is available to enhance protein immobilization, which is confirmed by measuring model protein interaction between human immunoglobulin G (H-IgG) and goat anti-H-IgG (G-H-IgG) with fluorescence microscopy and surface plasmon resonance imaging (SPRi). As expected, the SPRi signals of H-IgG coating on 3D PAA brushes pattern and further measuring specific binding with G-H-IgG are all larger than that of 3D PAA brushes without pattern and 2D bare gold surface. We further revealed that this surface can be used for high-throughput screening and clinical diagnosis by label-free assaying of Hepatitis-B-Virus surface antibody (HBsAb) with Hepatitis-B-Virus surface antigen (HBsAg) concentration array chip. The linearity range for HBsAb assay is wider than that of conventional ELISA method.

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

PubMed

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.

Structure zone diagram and particle incorporation of nickel brush plated composite coatings

PubMed Central

Isern, L.; Impey, S.; Almond, H.; Clouser, S. J.; Endrino, J. L.

2017-01-01

This work studies the deposition of aluminium-incorporated nickel coatings by brush electroplating, focusing on the electroplating setup and processing parameters. The setup was optimised in order to increase the volume of particle incorporation. The optimised design focused on increasing the plating solution flow to avoid sedimentation, and as a result the particle transport experienced a three-fold increase when compared with the traditional setup. The influence of bath load, current density and the brush material used was investigated. Both current density and brush material have a significant impact on the morphology and composition of the coatings. Higher current densities and non-abrasive brushes produce rough, particle-rich samples. Different combinations of these two parameters influence the surface characteristics differently, as illustrated in a Structure Zone Diagram. Finally, surfaces featuring crevices and peaks incorporate between 3.5 and 20 times more particles than smoother coatings. The presence of such features has been quantified using average surface roughness Ra and Abbott-Firestone curves. The combination of optimised setup and rough surface increased the particle content of the composite to 28 at.%. PMID:28300159

Structure zone diagram and particle incorporation of nickel brush plated composite coatings

NASA Astrophysics Data System (ADS)

Isern, L.; Impey, S.; Almond, H.; Clouser, S. J.; Endrino, J. L.

2017-03-01

This work studies the deposition of aluminium-incorporated nickel coatings by brush electroplating, focusing on the electroplating setup and processing parameters. The setup was optimised in order to increase the volume of particle incorporation. The optimised design focused on increasing the plating solution flow to avoid sedimentation, and as a result the particle transport experienced a three-fold increase when compared with the traditional setup. The influence of bath load, current density and the brush material used was investigated. Both current density and brush material have a significant impact on the morphology and composition of the coatings. Higher current densities and non-abrasive brushes produce rough, particle-rich samples. Different combinations of these two parameters influence the surface characteristics differently, as illustrated in a Structure Zone Diagram. Finally, surfaces featuring crevices and peaks incorporate between 3.5 and 20 times more particles than smoother coatings. The presence of such features has been quantified using average surface roughness Ra and Abbott-Firestone curves. The combination of optimised setup and rough surface increased the particle content of the composite to 28 at.%.

Structure zone diagram and particle incorporation of nickel brush plated composite coatings.

PubMed

Isern, L; Impey, S; Almond, H; Clouser, S J; Endrino, J L

2017-03-16

This work studies the deposition of aluminium-incorporated nickel coatings by brush electroplating, focusing on the electroplating setup and processing parameters. The setup was optimised in order to increase the volume of particle incorporation. The optimised design focused on increasing the plating solution flow to avoid sedimentation, and as a result the particle transport experienced a three-fold increase when compared with the traditional setup. The influence of bath load, current density and the brush material used was investigated. Both current density and brush material have a significant impact on the morphology and composition of the coatings. Higher current densities and non-abrasive brushes produce rough, particle-rich samples. Different combinations of these two parameters influence the surface characteristics differently, as illustrated in a Structure Zone Diagram. Finally, surfaces featuring crevices and peaks incorporate between 3.5 and 20 times more particles than smoother coatings. The presence of such features has been quantified using average surface roughness Ra and Abbott-Firestone curves. The combination of optimised setup and rough surface increased the particle content of the composite to 28 at.%.

A New Tribological Test for Candidate Brush Seal Materials Evaluation

NASA Technical Reports Server (NTRS)

Fellenstein, James A.; Dellacorte, Christopher

1994-01-01

A new tribological test for candidate brush seal materials evaluation has been developed. The sliding contact between the brush seal wires and their mating counterface journal is simulated by testing a small tuft of wire against the outside diameter of a high speed rotating shaft. The test configuration is similar to a standard block on ring geometry. The new tester provides the capability to measure both the friction and wear of candidate wire and counterface materials under controlled loading conditions in the gram to kilogram range. A wide test condition latitude of speeds (1 to 27 m/s), temperatures (25 to 700 C), and loads (0.5 to 10 N) enables the simulation of many of the important tribological parameters found in turbine engine brush seals. This paper describes the new test rig and specimen configuration and presents initial data for candidate seal materials comparing tuft test results and wear surface morphology to field tested seal components.

Children's toothbrushing frequency: the influence of parents' rationale for brushing, habits and family routines.

PubMed

Trubey, Rob J; Moore, Simon C; Chestnutt, Ivor G

2015-01-01

To assess the relationship between parental and family factors and children's toothbrushing frequency at different times of day. A cross-sectional questionnaire survey of predominantly low-socio-economic status parents of children aged 3-6 years (n = 296) in South Wales, UK. Data were collected on the child's weekly toothbrushing frequency (morning and evening), the parents' rationale for brushing their child's teeth in the morning and evening, the strength of a parent's habit for brushing a child's teeth in the morning and evening, and the extent to which the family's daily routines were stable from day to day. Socio-demographic details were also collected. Reported weekly brushing frequency was significantly (p < 0.001) higher in the morning (mean ± SD: 6.57 ± 1.37) than the evening (mean ± SD: 5.99 ± 2.15). Parents had significantly (p < 0.001) more interest in the cosmetic benefits of toothbrushing in the morning compared to the evening. Multivariate analysis showed that an increasing focus on the cosmetic benefits of toothbrushing was associated with significantly (p < 0.05) less weekly brushing in the evening. The extent to which brushing a child's teeth was 'habitual' was significantly (p < 0.001) associated with weekly toothbrushing frequency at both times of day. Parents' rationale for brushing their children's teeth can vary at both an individual level and at different times of day. Understanding these variations is important in designing interventions to improve brushing frequency for at-risk children. The results also demonstrate habituation as being an important factor in understanding toothbrushing frequency. Further research is required to understand the mechanisms involved in habit formation and maintenance with children's oral hygiene behaviour.

USAXS analysis of concentration-dependent self-assembling of polymer-brush-modified nanoparticles in ionic liquid: [I] concentrated-brush regime

NASA Astrophysics Data System (ADS)

Nakanishi, Yohei; Ishige, Ryohei; Ogawa, Hiroki; Sakakibara, Keita; Ohno, Kohji; Morinaga, Takashi; Sato, Takaya; Kanaya, Toshiji; Tsujii, Yoshinobu

2018-03-01

Using ultra-small angle X-ray scattering (USAXS), we analyzed the higher-order structures of nanoparticles with a concentrated brush of an ionic liquid (IL)-type polymer (concentrated-polymer-brush-modified silica particle; PSiP) in an IL and the structure of the swollen shell layer of PSiP. Homogeneous mixtures of PSiP and IL were successfully prepared by the solvent-casting method involving the slow evaporation of a volatile solvent, which enabled a systematic study over an exceptionally wide range of compositions. Different diffraction patterns as a function of PSiP concentration were observed in the USAXS images of the mixtures. At suitably low PSiP concentrations, the USAXS intensity profile was analyzed using the Percus-Yevick model by matching the contrast between the shell layer and IL, and the swollen structure of the shell and "effective diameter" of the PSiP were evaluated. This result confirms that under sufficiently low pressures below and near the liquid/crystal-threshold concentration, the studied PSiP can be well described using the "hard sphere" model in colloidal science. Above the threshold concentration, the PSiP forms higher-order structures. The analysis of diffraction patterns revealed structural changes from disorder to random hexagonal-closed-packing and then face-centered-cubic as the PSiP concentration increased. These results are discussed in terms of thermodynamically stable "hard" and/or "semi-soft" colloidal crystals, wherein the swollen layer of the concentrated polymer brush and its structure play an important role.

Experience of maintaining tooth brushing for children born with a cleft lip and/or palate.

PubMed

Lin, Yin-Ling; Davies, Karen; Callery, Peter

2017-08-24

Children with a Cleft Lip and/or Palate (CL/P) have been reported to have poorer oral health than those without the condition. The consequences for these children can be particularly problematic due to implications for future treatments. Tooth brushing is an important behaviour contributing to children's oral health, but is under researched in the CL/P population. The aim of the study is to explore the experience of maintaining tooth brushing among children in the United Kingdom (UK) with a CL/P and their parents. Semi-structured interviews were carried out with twenty-two parents and sixteen children with a CL/P (5-11 years), recruited at a cleft centre in the UK. Thematic analysis was used for data analysis. Three key themes were drawn from the qualitative data: first, parents of children with a CL/P generally had strong motivation to look after their children's teeth but children's motivation was inconsistent. Second, parents were primary enablers of children's tooth brushing behaviour, often employing approaches adapted to their child's characteristics to encourage tooth brushing. Third, a range of obstacles were encountered by parents and children in maintaining regular tooth brushing behaviours. They reported obstacles such as issues related to CL/P, 'forgetting' and childhood illness. The paper suggests that parents of children with a CL/P need support to enact their intention to maintain regular tooth brushing and prioritise tooth brushing within the context of demanding and dynamic family life.

21 CFR 886.1090 - Haidinger brush.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Haidinger brush. 886.1090 Section 886.1090 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL... viewed by the patient through a Nicol prism and intended to evaluate visual function. It may include a...

Grafted Polystyrene Monolayer Brush as Both Negative and Positive Tone Electron Beam Resist.

PubMed

Aydinoglu, Ferhat; Yamada, Hirotaka; Dey, Ripon K; Cui, Bo

2017-05-23

Although spin coating is the most widely used electron-beam resist coating technique in nanolithography, it cannot typically be applied for nonflat or irregular surfaces. Here, we demonstrate that monolayer polystyrene brush can be grafted on substrates and used as both positive and negative electron-beam resist, which can be applied for such unconventional surfaces. Polystyrene is a popular negative resist when using solvent developer but solvent cannot be used for grafted polystyrene brush that is firmly bonded to the substrate. Instead, we employed two unconventional development methods to lead polystyrene brush to positive or negative tone behavior. Negative tone was achieved by thermal development at 300 °C because exposed thus cross-linked polystyrene brush is more thermally stable against vaporization than unexposed linear one. Surprisingly, positive tone behavior occurred when the brush was grafted onto an aluminum (Al) layer and the film stack was developed using diluted hydrofluoric acid (HF) that etched the underlying Al layer. By transferring the patterns into the silicon (Si) substrates using the thin Al layer as a sacrificial hard mask for dry etch, well-defined structures in Si were obtained in two different electron-beam resist tones as well as in nonflat surfaces.

A versatile platform for precise synthesis of asymmetric molecular brush in one shot.

PubMed

Xu, Binbin; Feng, Chun; Huang, Xiaoyu

2017-08-24

Asymmetric molecular brushes emerge as a unique class of nanostructured polymers, while their versatile synthesis keeps a challenge for chemists. Here we show the synthesis of well-defined asymmetric molecular double-brushes comprising two different side chains linked to the same repeat unit along the backbone by one-pot concurrent atom transfer radical polymerization (ATRP) and Cu-catalyzed azide/alkyne cycloaddition (CuAAC) reaction. The double-brushes are based on a poly(Br-acrylate-alkyne) homopolymer possessing an alkynyl for CuAAC reaction and a 2-bromopropionate initiating group for ATRP in each repeat unit. The versatility of this one-shot approach is demonstrated by CuAAC reaction of alkynyl/poly(ethylene oxide)-N 3 and ATRP of various monomers. We also show the quantitative conversion of pentafluorophenyl ester groups to amide groups in side chains, allowing for the further fabrication of diverse building blocks. This work provides a versatile platform for facile synthesis of Janus-type double-brushes with structural and functional control, in a minimum number of reactions.Producing well-defined polymer compositions and structures facilitates their use in many different applications. Here the authors show the synthesis of well-defined asymmetric double-brushes by a one-pot concurrent atom transfer radical polymerization and Cu-catalyzed Click reaction.

Ponderosa pine response to fertilization: influence of brush removal and soil type

Treesearch

Robert F. Powers; Grant D. Jackson

1978-01-01

First-year results of fertilization in a young ponderosa pine plantation on two contrasting soils were analyzed. Trees testing low in foliar nitrogen responded strongly to fertilization where brush had been removed, but failed to respond if brush remained. Height growth was doubled by certain treatment combinations on the less fertile Mariposa soil, but was not...

Early brush control promotes growth of ponderosa pine planted on bulldozed site

Treesearch

Jay R. Bentley; Stanley B. Carpenter; David A. Blakeman

1971-01-01

Test plots in a brushfield near Mount Shasta, California, were cleared by bulldozing in 1961, and planted with ponderosa pine seedlings in 1962. Brush regrowth was subjected to varying levels of control by spraying with herbicides. In the first 5 years, brush control definitely promoted the growth of pine seedlings. And this early control also promises to reduce the...

Molecular dynamics study of the adsorption of anionic surfactant in a nonionic polymer brush.

PubMed

Wang, Hua; Zhang, Heng; Yuan, Shiling; Liu, Chengbu; Xu, Zhen

2014-06-01

The adsorption of the anionic surfactant, sodium dodecylsulfate (SDS) in poly(ethylene oxide) (PEO) brush was studied by molecular dynamics simulations. Our simulations revealed that surfactant can adsorb in polymer brush as micellar aggregates and the polymer would reside at the hydrocarbon-water interface of SDS micelles. This association between surfactant and polymer was mainly driven by the hydrophobic interaction between the polymer and surfactant tails. In the simulation, with the increasing of surfactant concentration, a plateau value representing saturated adsorption was observed. The height of polymer brush was mainly affected by the adsorbed surfactant at low grafting density of polymer; however, it was primarily controlled by the grafting density at high grafting density. Our conclusions at the molecular level were in close agreement with experiment about the adsorption of surfactant in polymer brushes.

Friction, wear and noise of slip ring and brush contacts for synchronous satellite use.

NASA Technical Reports Server (NTRS)

Lewis, N. E.; Cole, S. R.; Glossbrenner, E. W.; Vest, C. E.

1972-01-01

A program is being conducted for testing of slip rings for synchronous orbit application. Instrumentation systems necessary for monitoring electrical noise, friction, and brush wear at atmospheric pressure and at less than 50 ntorr have been developed. A multiplex scheme necessary for the simultaneous recording of brush displacement, friction, and electrical noise has also been developed. Composite brushes consisting of silver-molybdenum disulfide-graphite and silver-niobium diselenide-graphite have been employed on rings of coin silver and rhodium plate. Four contact combinations have been tested during an ambient condition run-in at 150 rpm and a humidity sequence at 0.1 rpm. The first six months of the two year vacuum test at 0.1 rpm have been completed. Electrical noise, friction and brush wear data recorded during these periods have been analyzed.

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

PubMed

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.

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

PubMed

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.

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

PubMed Central

2017-01-01

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. PMID:28691078

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

PubMed

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.

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

PubMed

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.

Regression modeling and prediction of road sweeping brush load characteristics from finite element analysis and experimental results.

PubMed

Wang, Chong; Sun, Qun; Wahab, Magd Abdel; Zhang, Xingyu; Xu, Limin

2015-09-01

Rotary cup brushes mounted on each side of a road sweeper undertake heavy debris removal tasks but the characteristics have not been well known until recently. A Finite Element (FE) model that can analyze brush deformation and predict brush characteristics have been developed to investigate the sweeping efficiency and to assist the controller design. However, the FE model requires large amount of CPU time to simulate each brush design and operating scenario, which may affect its applications in a real-time system. This study develops a mathematical regression model to summarize the FE modeled results. The complex brush load characteristic curves were statistically analyzed to quantify the effects of cross-section, length, mounting angle, displacement and rotational speed etc. The data were then fitted by a multiple variable regression model using the maximum likelihood method. The fitted results showed good agreement with the FE analysis results and experimental results, suggesting that the mathematical regression model may be directly used in a real-time system to predict characteristics of different brushes under varying operating conditions. The methodology may also be used in the design and optimization of rotary brush tools. Copyright © 2015 Elsevier Ltd. All rights reserved.

Cholinergic urethral brush cells are widespread throughout placental mammals.

PubMed

Deckmann, Klaus; Krasteva-Christ, Gabriela; Rafiq, Amir; Herden, Christine; Wichmann, Judy; Knauf, Sascha; Nassenstein, Christina; Grevelding, Christoph G; Dorresteijn, Adriaan; Chubanov, Vladimir; Gudermann, Thomas; Bschleipfer, Thomas; Kummer, Wolfgang

2015-11-01

We previously identified a population of cholinergic epithelial cells in murine, human and rat urethrae that exhibits a structural marker of brush cells (villin) and expresses components of the canonical taste transduction signaling cascade (α-gustducin, phospholipase Cβ2 (PLCβ2), transient receptor potential cation channel melanostatin 5 (TRPM5)). These cells serve as sentinels, monitoring the chemical composition of the luminal content for potentially hazardous compounds such as bacteria, and initiate protective reflexes counteracting further ingression. In order to elucidate cross-species conservation of the urethral chemosensory pathway we investigated the occurrence and molecular make-up of urethral brush cells in placental mammals. We screened 11 additional species, at least one in each of the five mammalian taxonomic units primates, carnivora, perissodactyla, artiodactyla and rodentia, for immunohistochemical labeling of the acetylcholine synthesizing enzyme, choline acetyltransferase (ChAT), villin, and taste cascade components (α-gustducin, PLCβ2, TRPM5). Corresponding to findings in previously investigated species, urethral epithelial cells with brush cell shape were immunolabeled in all 11 mammals. In 8 species, immunoreactivities against all marker proteins and ChAT were observed, and double-labeling immunofluorescence confirmed the cholinergic nature of villin-positive and chemosensory (TRPM5-positive) cells. In cat and horse, these cells were not labeled by the ChAT antiserum used in this study, and unspecific reactions of the secondary antiserum precluded conclusions about ChAT-expression in the bovine epithelium. These data indicate that urethral brush cells are widespread throughout the mammalian kingdom and evolved not later than about 64.5millionyears ago. Copyright © 2015 Elsevier B.V. All rights reserved.

Poor oral health, that is, decreased frequency of tooth brushing, is associated with endothelial dysfunction.

PubMed

Kajikawa, Masato; Nakashima, Ayumu; Maruhashi, Tatsuya; Iwamoto, Yumiko; Iwamoto, Akimichi; Matsumoto, Takeshi; Hidaka, Takayuki; Kihara, Yasuki; Chayama, Kazuaki; Goto, Chikara; Taguchi, Akira; Noma, Kensuke; Higashi, Yukihito

2014-01-01

 Poor oral health is an independent predictor of cardiovascular outcome. Endothelial dysfunction is the initial step of atherosclerosis, resulting in cardiovascular outcomes; but there is no information on the association between oral health and endothelial function. The purpose of this study was to determine the relationships between oral health and endothelial function.  A total of 190 subjects who underwent health examinations (mean age, 57±18 years), including patients with cardiovascular disease, completed a questionnaire on oral health and frequency of tooth brushing, and underwent measurement of vascular function, flow-mediated vasodilation (FMD) and nitroglycerine-induced vasodilation. The subjects were divided into 2 groups according to frequency of tooth brushing (≥twice/day and brushing group as compared to the ≥twice/day tooth brushing group (3.3±2.2% vs. 5.0±3.0%, P<0.001). There was no significant difference in nitroglycerine-induced vasodilation between the 2 groups. On multiple logistic regression analysis, tooth brushing brushing, is associated with endothelial dysfunction.  

Metallographic Analysis of Brush Bristle and Integrity Testing of Brush Seal in Shroud Ring of T-700 Engine

NASA Technical Reports Server (NTRS)

Hendricks, Robert C.; Griffin, Thomas A.; Bobula, George A.; Bill, Robert C.; Hull, David R.; Csavina, Kristine R.

1995-01-01

Post-test investigation of a T-700 engine brush seal found regions void of bristles ('yanked out'), regions of bent-over bristles near the inlet, some 'snapped' bristles near the fence, and a more uniform 'smeared' bristle interface between the first and last axial rows of bristles. Several bristles were cut from the brush seal, wax mounted, polished, and analyzed. Metallographic analysis of the bristles near the rub tip showed tungsten-rich phases uniformly distributed throughout the bristle with no apparent change within 1 to 2 micron of the interface except for possibly a small amount of titanium, which would represent a transfer from the rotor. Analysis of the bristle wear face showed nonuniform tungsten, which is indicative of material resolidification. The cut end contained oxides and internal fractures; the worn end was covered with oxide scale. Material losses due to wear and elastoplastic deformation within the shear zone and third-body lubrication effects in the contact zone are discussed.

In Situ Infrared Ellipsometry for Protein Adsorption Studies on Ultrathin Smart Polymer Brushes in Aqueous Environment

DOE PAGES

Kroning, Annika; Furchner, Andreas; Aulich, Dennis; ...

2015-02-10

The protein-adsorbing and -repelling properties of various smart nanometer-thin polymer brushes with high potential for biosensing and biomedical applications are studied by in-situ infrared-spectroscopic ellipsometry (IRSE). IRSE as a highly sensitive non-destructive technique allows us to investigate protein adsorption on polymer brushes in aqueous environment in dependence of external stimuli like temperature and pH. These stimuli are, for instance, relevant in switchable mixed brushes containing poly(N-isopropyl acrylamide) and poly(acrylic acid), respectively. We use such brushes as model surfaces for controlling protein adsorption of human serum albumin and human fibrinogen. IRSE can distinguish between polymer-specific vibrational bands, which yield insights intomore » the hydration state of the brushes, and changes in the protein-specific amide bands, which are related to changes of the protein secondary structure.« less

Simulation and modelling of slip flow over surfaces grafted with polymer brushes and glycocalyx fibres

PubMed Central

Deng, Mingge; Li, Xuejin; Liang, Haojun; Caswell, Bruce; Karniadakis, George Em

2013-01-01

Fabrication of functionalized surfaces using polymer brushes is a relatively simple process and parallels the presence of glycocalyx filaments coating the luminal surface of our vasculature. In this paper, we perform atomistic-like simulations based on dissipative particle dynamics (DPD) to study both polymer brushes and glycocalyx filaments subject to shear flow, and we apply mean-field theory to extract useful scaling arguments on their response. For polymer brushes, a weak shear flow has no effect on the brush density profile or its height, while the slip length is independent of the shear rate and is of the order of the brush mesh size as a result of screening by hydrodynamic interactions. However, for strong shear flow, the polymer brush is penetrated deeper and is deformed, with a corresponding decrease of the brush height and an increase of the slip length. The transition from the weak to the strong shear regime can be described by a simple ‘blob’ argument, leading to the scaling γ̇0 ∝ σ3/2, where γ̇0 is the critical transition shear rate and σ is the grafting density. Furthermore, in the strong shear regime, we observe a cyclic dynamic motion of individual polymers, causing a reversal in the direction of surface flow. To study the glycocalyx layer, we first assume a homogeneous flow that ignores the discrete effects of blood cells, and we simulate microchannel flows at different flow rates. Surprisingly, we find that, at low Reynolds number, the slip length decreases with the mean flow velocity, unlike the behaviour of polymer brushes, for which the slip length remains constant under similar conditions. (The slip length and brush height are measured with respect to polymer mesh size and polymer contour length, respectively.) We also performed additional DPD simulations of blood flow in a tube with walls having a glycocalyx layer and with the deformable red blood cells modelled accurately at the spectrin level. In this case, a plasma cell

The dynamics of complex formation between amylose brushes on gold and fatty acids by QCM-D.

PubMed

Cao, Zheng; Tsoufis, Theodoros; Svaldo-Lanero, Tiziana; Duwez, Anne-Sophie; Rudolf, Petra; Loos, Katja

2013-10-14

Amylose brushes were synthesized by enzymatic polymerization with glucose-1-phosphate as monomer and rabbit muscle phosphorylase b as catalyst on gold-covered surfaces of a quartz crystal microbalance. Fourier transform infrared (FT-IR) spectra confirmed the presence of the characteristic absorption peaks of amylose between 3100 cm(-1) and 3500 cm(-1). The thickness of the amylose brushes-measured by Spectroscopic Ellipsometry--can be tailored from 4 to 20 nm, depending on the reaction time. The contour length of the stretched amylose chains on gold surfaces has been evaluated by single molecule force spectroscopy, and a total chain length of about 20 nm for 16.2 nm thick amylose brushes was estimated. X-ray photoelectron spectroscopy (XPS) was employed to characterize the amylose brushes before and after the adsorption of fatty acids. The dynamics of inclusion complex formation between amylose brushes and two fatty acids (octanoic acid and myristic acid) with different chain length was investigated as a function of time using a quartz crystal microbalance with dissipation monitoring (QCM-D) immersed in the liquid phase. QCM-D signals including the frequency and dissipation shifts elucidated the effects of the fatty acid concentration, the solvent types, the chain length of the fatty acids and the thickness of the amylose brushes on the dynamics of fatty acid molecule adsorption on the amylose brush-modified sensor surfaces.

Decreased frequency and duration of tooth brushing is a risk factor for endothelial dysfunction.

PubMed

Matsui, Shogo; Kajikawa, Masato; Maruhashi, Tatsuya; Iwamoto, Yumiko; Iwamoto, Akimichi; Oda, Nozomu; Kishimoto, Shinji; Hidaka, Takayuki; Kihara, Yasuki; Chayama, Kazuaki; Goto, Chikara; Aibara, Yoshiki; Nakashima, Ayumu; Noma, Kensuke; Taguchi, Akira; Higashi, Yukihito

2017-08-15

Periodontal disease is associated with endothelial dysfunction, leading to cardiovascular disease. The effect of detailed tooth brushing behavior, not only frequency but also duration of tooth brushing, on endothelial function is unclear. The purpose of this study was to evaluate the relationships of detailed methods of tooth brushing with vascular function. We evaluated flow-mediated vasodilation (FMD), nitroglycerine-induced vasodilation, and frequency and duration of tooth brushing in 896 subjects. We divided the subjects into three groups according to the frequency and duration of tooth brushing: low frequency and short duration group (brushing group was significantly associated with an increased odds ratio of a low FMD tertile after adjustment for conventional risk factors (OR: 2.25, 95% CI: 1.39-3.59; P<0.001). These findings suggest that low frequency and short duration of tooth brushing are associated with endothelial dysfunction. URL for clinical trial: http://UMIN; registration number for clinical trial: UMIN000003409. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

Grafting of PMMA brushes layer on Cu surface to create a stable superhydrophobic surface

NASA Astrophysics Data System (ADS)

Zhang, Junhong; Cai, Junyan; Li, Ming

2016-11-01

In this paper, poly(methyl methacrylate) (PMMA) brushes were grafted on Cu micro-cone structured substrate by a simple one-step cathodic electro-initiated polymerization method which was carried out in aqueous solution at room temperature in the open air. The PMMA brushes were continuous, uniform and thickness-controllable, and it covalently bonded to the Cu surface. In the brushes, nitrophenyl moieties acted as cross-linker between PMMA chains. After removed from the solution followed by treated with water, the PMMA brushes (basically a hydrophilic material)/micro-cone structured Cu surface was hydrophilic with water contact angle (CA) of 74.4°. However, it exhibited superhydrophobicity by treating it in the acetone. The conversion from hydrophilic surface to superhydrophobic one may due to rearrangement of nitrophenyl moieties and PMMA chains at the topmost of the brushes. In addition, its water CA increased with grafting time of the brushes from 145° to about 166°, because there was no available space in thinner film for group reorientation. The surface was conversed to hydrophilic again after treated with hot water, but it was still superhydrophobic after treated in water at room temperature. This revealed that the group reorientation also easily occurred in hot water like in the acetone. More importantly, the surface retained good superhydrophobic stability in acidic environment and in long-time storage. Furthermore, the superhydrophobic surface had excellent resistance that can provide effective protection for the bare Cu substrate.

Temperature and pH Dual-Responsive Core-Brush Nanocomposite for Enrichment of Glycoproteins.

PubMed

Jiang, Lingdong; Messing, Maria E; Ye, Lei

2017-03-15

In this report, we present a novel modular approach to the immobilization of a high density of boronic acid ligands on thermoresponsive block copolymer brushes for effective enrichment of glycoproteins via their synergistic multiple covalent binding with the immobilized boronic acids. Specifically, a two-step, consecutive surface-initiated atom transfer radical polymerization (SI-ATRP) was employed to graft a flexible block copolymer brush, pNIPAm-b-pGMA, from an initiator-functionalized nanosilica surface, followed by postpolymerization modification of the pGMA moiety with sodium azide. Subsequently, an alkyne-tagged boronic acid (PCAPBA) was conjugated to the polymer brush via a Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) click reaction, leading to a silica-supported polymeric hybrid material, Si@pNIPAm-b-pBA, with a potent glycol binding affinity. The obtained core-brush nanocomposite was systematically characterized with regard to particle size, morphology, organic content, brush density, and number of immobilized boronic acids. We also studied the characteristics of glycoprotein binding of the nanocomposite under different conditions. The nanocomposite showed high binding capacities for ovalbumin (OVA) (98.0 mg g -1 ) and horseradish peroxidase (HRP) (26.8 mg g -1 ) in a basic buffer (pH 9.0) at 20 °C. More importantly, by adjusting the pH and temperature, the binding capacities of the nanocomposite can be tuned, which is meaningful for the separation of biological molecules. In general, the synthetic approach developed for the fabrication of block copolymer brushes in the nanocomposite opened new opportunities for the design of more functional hybrid materials that will be useful in bioseparation and biomedical applications.

Surface grafted glycopolymer brushes to enhance selective adhesion of HepG2 cells.

PubMed

Chernyy, Sergey; Jensen, Bettina E B; Shimizu, Kyoko; Ceccato, Marcel; Pedersen, Steen Uttrup; Zelikin, Alexander N; Daasbjerg, Kim; Iruthayaraj, Joseph

2013-08-15

This work demonstrates the application of carbohydrate based methacrylate polymer brush, poly(2-lactobionamidoethyl methacrylate), for the purpose of cell adhesion studies. The first part of the work illustrates the effects of the structure of the aminosilane based ATRP initiator layer 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 of the cell periphery. On the other hand the cells on bare glass substrate display spheroid morphology. Further analysis using ToF-SIMS imaging shows that the HepG2 cells on glycopolymer surfaces is enriched with protein fragment along the cell periphery which is absent in the case of cells on bare glass substrate. It is suggested that the interaction of the galactose units of the polymer brush with the asialoglycoprotein receptor (ASGPR) of HepG2 cells has resulted in the protein enrichment along the cell periphery. Copyright © 2013 Elsevier Inc. All rights reserved.

Poly(ethylene oxide) Chains Are Not ``Hydrophilic'' When They Exist As Polymer Brush Chains

NASA Astrophysics Data System (ADS)

Lee, Hoyoung; Kim, Dae Hwan; Witte, Kevin N.; Ohn, Kimberly; Choi, Je; Kim, Kyungil; Meron, Mati; Lin, Binhua; Akgun, Bulent; Satija, Sushil; Won, You-Yeon

2012-02-01

By using a combined experimental and theoretical approach, a model poly(ethylene oxide) (PEO) brush system, prepared by spreading a poly(ethylene oxide)-poly(n-butyl acrylate) (PEO-PnBA) amphiphilic diblock copolymer onto an air-water interface, was investigated. The polymer segment density profiles of the PEO brush in the direction normal to the air-water interface under various grafting density conditions were determined from combined X-ray and neutron reflectivity data. In order to achieve a theoretically sound analysis of the reflectivity data, we developed a new data analysis method that uses the self-consistent field theoretical modeling as a tool for predicting expected reflectivity results for comparison with the experimental data. Using this new data analysis method, we discovered that the effective Flory-Huggins interaction parameter of the PEO brush chains is significantly greater than that corresponding to the theta condition, suggesting that contrary to what is more commonly observed for PEO in normal situations, the PEO chains are actually not ``hydrophilic'' when they exist as polymer brush chains, because of the many body interactions forced to be effective in the brush situation.

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

PubMed

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.

Border Security: The Role of the U.S. Border Patrol

DTIC Science & Technology

2010-08-11

officials have jointly administered this program to return at least 82,558 Mexican nationals from the Arizona- Sonora desert to the interior of Mexico ...international borders with Mexico and Canada and the coastal waters around Florida and Puerto Rico. However, there are significant geographic...political, and immigration-related differences between the northern border with Canada and the Southwest border with Mexico . Accordingly, the USBP deploys

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

PubMed

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.

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

PubMed

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.

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

PubMed

Munirathinam, Rajesh; Ricciardi, Roberto; Egberink, Richard J M; Huskens, Jurriaan; Holtkamp, Michael; Wormeester, Herbert; Karst, Uwe; Verboom, Willem

2013-01-01

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

An, Sung Yup; Ahn, Kwangseok; Kim, Doris Yangsoo

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 desorptionmore » 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.« less

A theoretical study of colloidal forces near an amphiphilic polymer brush

NASA Astrophysics Data System (ADS)

Wu, Jianzhong