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Sample records for brushes electricity

  1. Numerical investigation of the contraction of neutral-charged diblock copolymer brushes in electric fields.

    Science.gov (United States)

    Chen, Yuwei; Li, Haiming; Zhu, Yuejin; Tong, Chaohui

    2016-03-31

    Using self-consistent field theory (SCFT), the contraction of neutral-charged A-B diblock copolymer brushes in electric fields generated by opposite surface charges on two parallel electrodes has been numerically investigated. The diblock copolymer chains were grafted with the free end of the neutral block to one electrode and immersed in a salt-free solution sandwiched between the two electrodes. The numerical results reveal that the charged monomers, A-B joint segment and the tail exhibit bimodal distributions under external electric fields, which are absent for homopolymer polyelectrolyte brushes. The dependences of the relative populations and peak positions of the two modes on various parameters such as block ratio, grafting density, chain length and strength of the applied electric field were systematically examined and the underlining mechanisms were elucidated. It was found in this study that, if the total amount of surface charges on the grafting electrode is no more than that of the counter-ions in the system, overall charge neutrality is generally maintained inside the brushes when including the contribution of surface charges on the grafting electrode. In such a case, the counter-ions expelled from the brushes are highly enriched in the immediate vicinity of the second electrode and an approximate charge balance between these expelled counter-ions and the opposite surface charges on the second electrode is achieved. PMID:26912335

  2. Residual stress induced wetting variation on electric brush-plated Cu film

    International Nuclear Information System (INIS)

    Nanocrystalline Cu film with a mirror surface finishing is prepared by the electric brush-plating technique. The as-prepared Cu film exhibits a superhydrophilic behavior with an apparent water contact angle smaller than 10°. A subsequent increase in the water contact angle and a final wetting transition from inherent hydrophilicity with water contact angle smaller than 90° to apparent hydrophobicity with water contact angle larger than 90° are observed when the Cu film is subjected to natural aging. Analysis based on the measurement of hardness with nanoindentation and the theory of the bond-order-length-strength correlation reveals that this wetting variation on the Cu film is attributed to the relaxation of residual stress generated during brush-plating deposition and a surface hydrophobization role associated with the broken bond polarization induced by surface nanostructure

  3. Effect of strain rate on tensile properties of electric brush-plated nanocrystalline copper

    International Nuclear Information System (INIS)

    Tensile properties of an electric brush-plated nanocrystalline Cu with an average grain size of 59 nm were investigated at different strain rates. This nanocrystalline Cu exhibits an excellent combination of strength and ductility with its ultimate tensile strength increasing from 635 MPa to 1000 MPa and total elongation decreasing from 15.8% to 9.9% as strain rate increases from 10−4s−1 to 1s−1. Analysis based on the characterization results of transmission electron microscopy (TEM), scanning electron microscopy (SEM) and general area detector diffraction detection system (GADDS) on the as-brush-plated and deformed NC specimens revealed that the excellent combination of strength and ductility arises from the enhanced dislocation strain hardening ability and the improved deformation accommodation role played by GB sliding

  4. Electric Double Layer electrostatics of spherical polyelectrolyte brushes with pH-dependent charge density

    Science.gov (United States)

    Li, Hao; Chen, Guang; Sinha, Shayandev; Das, Siddhartha; Soft Matter, Interfaces,; Energy Laboratory (Smiel) Team

    Understanding the electric double layer (EDL) electrostatics of spherical polyelectrolyte (PE) brushes, which are spherical particles grafted with PE layers, is essential for appropriate use of PE-grfated micro-nanoparticles for targeted drug delivery, oil recovery, water harvesting, emulsion stabilization, emulsion breaking, etc. Here we elucidate the EDL electrostatics of spherical PE brushes for the case where the PE exhibits pH-dependent charge density. This pH-dependence necessitates the consideration of explicit hydrogen ion concentration, which in turn dictates the distribution of monomers along the length of the grafted PE. This monomer distribution is shown to be a function of the nature of the sphere (metallic or a charged or uncharged dielectric or a liquid-filled sphere). All the calculations are performed for the case where the PE electrostatics can be decoupled from the PE elastic and excluded volume effects. Initial predictions are also provided for the case where such decoupling is not possible.

  5. Polyaniline-Doped Spherical Polyelectrolyte Brush Nanocomposites with Enhanced Electrical Conductivity, Thermal Stability, and Solubility Property

    Directory of Open Access Journals (Sweden)

    Na Su

    2015-09-01

    Full Text Available The synthesis procedure and dopant are crucial to the electrical conductivity, thermal stability, and solubility properties of polyaniline (PANI. In this paper, high-performance PANI was synthesized by means of chemical oxidative polymerization using anionic spherical polyelectrolyte brushes (ASPB as dopant. The bonding structure, crystallographic structure, morphology, and thermal stability of the conductive nanocomposite were analyzed by Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD, scanning electron microscopy (SEM, and thermo-gravimetric analysis (TGA respectively. Meanwhile, investigation on the electrical conductivity suggested that the room-temperature electrical conductivity of PANI doped with ASPB (PANI/ASPB was 19.3 S/cm, which was higher than that of PANI (7.0 S/cm, PANI doped with poly(sodium-p-styrenesulfonate (PSS (PANI/PSS (14.6 S/cm, PANI doped with SiO2 (PANI/SiO2 (18.2 S/cm, and PANI doped with canonic spherical polyelectrolyte brushes (CSPB (PANI/CSPB (8.0 S/cm. Meanwhile, the addition of ASPB improved the thermal stability and solubility properties of PANI. ASPB played the role of template. Conductive mechanism of PANI/ASPB nanocomposite can be explained by the theoretical models of three-dimensional variable range-hopping (3D VRH.

  6. Numerical self-consistent field theory study of the response of strong polyelectrolyte brushes to external electric fields

    International Nuclear Information System (INIS)

    The response of strong polyelectrolyte (PE) brushes grafted on an electrode to electric fields generated by opposite surface charges on the PE-grafted electrode and a second parallel electrode has been numerically investigated by self-consistent field theory. The influences of grafting density, average charge fraction, salt concentration, and mobile ion size on the variation of the brush height against an applied voltage bias were investigated. In agreement with molecular dynamics simulation results, a higher grafting density requires a larger magnitude of voltage bias to achieve the same amount of relative change in the brush height. In the experimentally relevant parameter regime of the applied voltage, the brush height becomes insensitive to the voltage bias when the grafting density is high. Including the contribution of surface charges on the grafting electrode, overall charge neutrality inside the PE brushes is generally maintained, especially for PE brushes with high grafting density and high average charge fraction. Our numerical study further reveals that the electric field across the two electrodes is highly non-uniform because of the complex interplay between the surface charges on the electrodes, the charges on the grafted PE chains, and counterions

  7. Numerical self-consistent field theory study of the response of strong polyelectrolyte brushes to external electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Chaohui, E-mail: tongchaohui@nbu.edu.cn [Department of Physics, Ningbo University, Ningbo, Zhejiang 315211 (China)

    2015-08-07

    The response of strong polyelectrolyte (PE) brushes grafted on an electrode to electric fields generated by opposite surface charges on the PE-grafted electrode and a second parallel electrode has been numerically investigated by self-consistent field theory. The influences of grafting density, average charge fraction, salt concentration, and mobile ion size on the variation of the brush height against an applied voltage bias were investigated. In agreement with molecular dynamics simulation results, a higher grafting density requires a larger magnitude of voltage bias to achieve the same amount of relative change in the brush height. In the experimentally relevant parameter regime of the applied voltage, the brush height becomes insensitive to the voltage bias when the grafting density is high. Including the contribution of surface charges on the grafting electrode, overall charge neutrality inside the PE brushes is generally maintained, especially for PE brushes with high grafting density and high average charge fraction. Our numerical study further reveals that the electric field across the two electrodes is highly non-uniform because of the complex interplay between the surface charges on the electrodes, the charges on the grafted PE chains, and counterions.

  8. Water Soluble Responsive Polymer Brushes

    Directory of Open Access Journals (Sweden)

    Andrew J. Parnell

    2011-12-01

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

  9. Anti-NMDA-R encephalitis: Should we consider extreme delta brush as electrical status epilepticus?

    Science.gov (United States)

    Chanson, Eve; Bicilli, Élodie; Lauxerois, Michel; Kauffmann, Sophie; Chabanne, Russell; Ducray, François; Honnorat, Jérome; Clavelou, Pierre; Rosenberg, Sarah

    2016-02-01

    Seizures are common clinical manifestations in anti-N-methyl-d-aspartate receptor (anti-NMDA-R) encephalitis, among other neurological and psychiatric symptoms. During the course of the disease, some specific EEG patterns have been described: generalized rhythmic delta activity (GRDA) and extreme delta brush (EDB). In comatose patients, the association of these EEG abnormalities with subtle motor manifestations can suggest ongoing non-convulsive status epilepticus (NCSE). We report the case of a 28-year-old woman admitted for a clinical presentation typical of anti-NMDA-R encephalitis, which was confirmed by CSF analysis. She was rapidly intubated because of severe dysautonomia and disturbed consciousness. Clinical examination revealed subtle paroxysmal and intermittent myoclonic and tonic movements, correlated on video-EEG with GRDA and/or EDB. NCSE was then suspected, but electroclinical manifestations persisted despite many anti-epileptic drugs combinations, or reappeared when barbiturate anesthesia was decreased. In order to confirm or dismiss the diagnosis, intracranial pressure (ICP) and surface video-EEG monitoring were performed simultaneously and revealed no ICP increase, thus being strongly against a diagnosis of seizures. Sedation was progressively weaned, and clinical condition as well as EEG appearance progressively improved. Literature review revealed 11 similar cases, including 2 with focal NCSE. Of the nine other cases, NCSE diagnosis was finally excluded in 5 cases. NCSE diagnosis in association with anti-NMDA-R encephalitis is sometimes very difficult and its occurrence might be overestimated. Video-EEG is highly recommended and more invasive techniques may sometimes be necessary. PMID:26922283

  10. Ureteral retrograde brush biopsy

    Science.gov (United States)

    Biopsy - brush - urinary tract; Retrograde ureteral brush biopsy cytology; Cytology - ureteral retrograde brush biopsy ... to be biopsied is rubbed with the brush. Biopsy forceps may be used instead to collect a ...

  11. Brushing your infant's teeth

    Science.gov (United States)

    ... gov/ency/patientinstructions/000769.htm Brushing Your Child’s Teeth To use the sharing features on this page, ... how to brush their teeth on their own. Tooth and Gum Care for Young Children You should ...

  12. Friction between Polymer Brushes

    OpenAIRE

    Sokoloff, J. B.

    2006-01-01

    By solving the equilibrium equations for a polymer in a neutral polymer brush, the degree of interpenetration of two polymer brushes in contact and near contact is calculated. These results are used to calculate values of the force of static friction in agreement with recent friction measurements for polymer brush lubricated surfaces. It is shown that at sufficiently light loads polymer brush coated surfaces can slide, with the load supported entirely by osmotic pressure, at a sufficiently la...

  13. Two-stage eutectic metal brushes

    Science.gov (United States)

    Hsu, John S [Oak Ridge, TN

    2009-07-14

    A two-stage eutectic metal brush assembly having a slip ring rigidly coupled to a shaft, the slip ring being electrically coupled to first voltage polarity. At least one brush is rigidly coupled to a second ring and slidingly engaged to the slip ring. Eutectic metal at least partially fills an annulus between the second ring and a stationary ring. At least one conductor is rigidly coupled to the stationary ring and electrically coupled to a second voltage polarity. Electrical continuity is maintained between the first voltage polarity and the second voltage polarity. Periodic rotational motion is present between the stationary ring and the second ring. Periodic rotational motion is also present between the brush and the slip ring.

  14. Rotating Brush Seal

    Science.gov (United States)

    Lattime, S. B.; Braun, M. J.; Choy. F. K.; Hendricks, R. C.; Steinetz, B. M.

    2006-01-01

    The proven technology of brush seals has been extended to the mitigation of problems arising from friction and wear at the bristle-rotor interface at high surface speeds. In prototype testing, the brush is mounted on, and free to rotate with the shaft, thus providing a complaint primary seal. A face seal positioned between the backing plate of the brush seal and the housing provides a secondary seal. The purpose of this paper is to demonstrate the interaction between the brush bristles and the shaft at high surface speeds as well as introduce a numerical model to simulate the bristle behavior. A test facility was constructed to study the effects of centrifugal forces on bristle deflection in a single rotating brush seal. The bristle-rotor interface was observed through a video camera, which utilized a high magnification borescope and a high frequency strobe light source. Rotational speeds of the rotor and the brush seal were measured by a magnetic and optical speed sensor, respectively. Preliminary results with speeds up to 11,000 rpm show no speed differential between the brush seal and rotor, or any instability problems associated with the brush seal. Bristle liftoff from the rotor is successfully captured on video.

  15. Charge Transport Properties in Polymer Brushes

    Science.gov (United States)

    Moog, Mark; Tsui, Frank; Vonwald, Ian; You, Wei

    Electrical transport properties in poly(3-methyl)thiophene (P3MT) brushes have been studied. The P3MT brushes correspond to a new type of surface-tethered, vertically oriented conjugated molecular wires, sandwiched between two metallic electrodes to form the electrode-molecule-electrode (EME) devices. P3MT is a highly conjugated polymer, a ''workhorse'' material for organic electronics and photonics. The P3MT brushes were grown on ITO surfaces with controlled length (between 2 and 100 nm). The top electrodes were transfer-printed Au films with lateral dimensions between 200 nm and 50 μm. I-V and differential conductance measurements were performed using conductive AFM and 4-terminal techniques. Tunneling and field-emission measurements in EME devices with molecular lengths mobility and the interplay between intra- and intermolecular transport have been investigated.

  16. Lubrication by glycoprotein brushes.

    Science.gov (United States)

    Zappone, Bruno; Ruths, Marina; Greene, George W.; Israelachvili, Jacob

    2006-03-01

    Grafted polyelectrolyte brushes show excellent lubricating properties under water and have been proposed as a model to study boundary lubrication in biological system. Lubricin, a glycoprotein of the synovial fluid, is considered the major boundary lubricant of articular joints. Using the Surface Force Apparatus, we have measured normal and friction forces between model surfaces (negatively charged mica, positively charged poly-lysine and aminothiol, hydrophobic alkanethiol) bearing adsorbed layers of lubricin. Lubricin layers acts like a versatile anti-adhesive, adsorbing on all the surfaces considered and creating a repulsion similar to the force between end-grafted polymer brushes. Analogies with polymer brushes also appear from bridging experiment, where proteins molecules are end-adsorbed on two opposing surfaces at the same time. Lubricin `brushes' show good lubricating ability at low applied pressures (P<0.5MPa), especially on negatively charged surfaces like mica. At higher load, the adsorbed layers wears and fails lubricating the surfaces, while still protecting the underlying substrate from wearing. Lubricin might thus be a first example of biological polyelectrolytes providing `brush-like' lubrication and wear-protection.

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-07-01

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

  19. Friction between Ring Polymer Brushes

    OpenAIRE

    2015-01-01

    Friction between ring-polymer brushes at melt densities sliding past each other are studied using extensive course-grained molecular dynamics simulations and scaling arguments, and the results are compared to the friction between linear-polymer brushes. We show that for a velocity range spanning over three decades, the frictional forces measured for ring-polymer brushes are half the corresponding friction in case of linear brushes. In the linear-force regime, the weak inter-digitation of two ...

  20. Endobiliary brush biopsy

    DEFF Research Database (Denmark)

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

    2006-01-01

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

  1. Smart photonic carbon brush

    Science.gov (United States)

    Morozov, Oleg G.; Kuznetsov, Artem A.; Morozov, Gennady A.; Nureev, Ilnur I.; Sakhabutdinov, Airat Z.; Faskhutdinov, Lenar M.; Artemev, Vadim I.

    2016-03-01

    Aspects of the paper relate to a wear monitoring system for smart photonic carbon brush. There are many applications in which regular inspection is not feasible because of a number of factors including, for example, time, labor, cost and disruptions due to down time. Thus, there is a need for a system that can monitor the wear of a component while the component is in operation or without having to remove the component from its operational position. We propose a new smart photonic method for characterization of carbon brush wear. It is based on the usage of advantages of the multiplicative response of FBG and LPFG sensors and its double-frequency probing. Additional measuring parameters are the wear rate, the brush temperature, the engine rotation speed, the hangs control, and rotor speed. Sensor is embedded in brush. Firstly the change of sensor length is used to measure wear value and its central wavelength shift for temperature ones. The results of modeling and experiments are presented.

  2. Friction between ring polymer brushes.

    Science.gov (United States)

    Erbaş, Aykut; Paturej, Jarosław

    2015-04-28

    Friction between ring polymer brush bilayers sliding past each other at melt densities is studied using extensive coarse-grained molecular dynamics simulations and scaling arguments, and the results are compared to the friction between bilayers of linear polymer brushes. We show that for a velocity range spanning over three decades, the frictional forces measured for ring polymer brushes are half of the corresponding friction in the case of linear brushes. In the linear-force regime, the weak inter-digitation between ring brush layers as compared to linear brushes leads also to a lower number of binary collisions between the monomers from opposing brushes. At high velocities, where the thickness of the inter-digitation between bilayers is on the order of monomer size regardless of brush topology, stretched segments of ring polymers adopt the double-stranded conformation. As a result, monomers of the double-stranded segments collide on average less with the monomers of the opposing ring brush even though a similar number of monomers occupies the inter-digitation layer for ring and linear brush bilayers. The numerical data obtained from our simulations are consistent with the proposed scaling analysis. Conformation-dependent friction reduction observed in ring brushes can have important consequences in non-equilibrium bulk systems. PMID:25747253

  3. Antifouling polymer brushes for biofunctional interfaces

    Czech Academy of Sciences Publication Activity Database

    Brynda, Eduard; Rodriguez-Emmenegger, Cesar Adolfo; Riedel, Tomáš; Houska, Milan

    Nice: European Materials Research Society, 2011. P.XV-4. [E- MRS 2011 Spring Meeting IUMRS ICAM 2011 & E- MRS / MRS Bilateral Conference on Energy. 09.05.2011-13.05.2011, Nice] R&D Projects: GA AV ČR KAN200670701 Institutional research plan: CEZ:AV0Z40500505 Keywords : surface modification * polymer brushes * protein resistant Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

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

    KAUST Repository

    Zhang, Ning

    2009-07-28

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

  5. The Unusual Conformational Behavior of Polyzwitterionic Brushes in Aqueous Solutions

    Science.gov (United States)

    Mao, Jun; Chen, Wei; Yuan, Guangcui; Yu, Jing; Tirrell, Matthew

    Polyzwitterions constitute a peculiar class of polyelectrolytes, which are electrically neutral polymers containing both a positive and a negative charge on each repeating unit. Surfaces coated with polyzwitterionic brushes are resistant to the nonspecific accumulation of proteins and microorganisms, making them excellent candidates for a wide range of antifouling applications, from biocompatible medical devices to marine coatings. The surrounding environment can dramatically influence the conformational behavior of polyzwitterionic brushes. High-density polyzwitterionic brushes poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) were synthesized using surface initiated atom-transfer radical polymerization, and neutron reflectivity (NR) measurements were performed to investigate the ionic strength dependence of the conformational behaviors of PMPC brushes in monovalent salt solutions. Despite the numerous observations of normal pure polyelectrolyte brushes, NR results showed that both the densely concentrated layer near the substrate surface and the relatively swollen layer into the solution have been observed in different q range in a single neutron reflectivity profile. These results will definitely help us to better understand the relationship between the solution behaviors of zwitterionic polymer brushes and their antifouling properties.

  6. Forces between asymmetric polymer brushes

    OpenAIRE

    Shim, D.F.K.; Cates, M. E.

    1990-01-01

    We study the equilibrium compression of asymmetric polymer brushes grafted on flat plates, under athermal and theta solvent conditions, using a lattice self-consistent field (SCF) approach. We find that the separation d between two plates coated asymmetrically with brushes of type 1 and 2, as a function of the force F, obeys the "bisection rule", d(F) = (d1(F) + d 2(F)) /2 where d1(F)and d 2(F) are the corresponding separations for the symmetric brushes of type 1 and 2 respectively.The bisect...

  7. Water Soluble Responsive Polymer Brushes

    OpenAIRE

    Parnell, Andrew J.; Weir, Michael P

    2011-01-01

    Responsive polymer brushes possess many interesting properties that enable them to control a range of important interfacial behaviours, including adhesion, wettability, surface adsorption, friction, flow and motility. The ability to design a macromolecular response to a wide variety of external stimuli makes polymer brushes an exciting class of functional materials, and has been made possible by advances in modern controlled polymerization techniques. In this review we discuss the physics of ...

  8. Scaling Laws for liquid and ion transport in nanochannels grafted with polyelectrolyte brushes

    Science.gov (United States)

    Chen, Guang; Sinha, Shayandev; Das, Siddhartha; Soft Matter, Interfaces,; Energy Laboratory (Smiel) Team

    Grafting nanochannels with polyelectrolyte (PE) brushes renders tremendous functionality to the nanochannels, making them capable of applications such as ion manipulation, ion sensing, current rectification, nanofluidic diode fabrication, and flow control. PE brush is a special case of polymers at interfaces; such brush-like structure is possible only when the grafting density (σ) is beyond a critical value. In this study, we shall propose scaling laws that identify σ-N(N is the size of the PE molecule) combination that simultaneously ensure that the grafted PE molecules adopt ''brush''-like configuration and the height of the PE brushes are smaller than the nanochannel half height. Secondly, we pinpoint the scaling conditions where the electrostatic effects associated with the PE brushes can be decoupled from the corresponding PE excluded volume and elastic effects; such de-coupling has tremendous connotation in context of modeling of electrostatics and transport at PE-brush-covered interfaces. Thirdly, we provide scaling arguments to quantify the dependence of the flow penetration depth into the PE brush as a function of the σ-N combination. Finally, our scaling estimates pinpoint the conditions where the flow or electric field induced deformation of the grafted nanochannel PE brushes can be neglected while modeling the pressure-driven or electroosmotic transport or ionic current in such nanochannels.

  9. Charge transferred in brush discharges

    Science.gov (United States)

    Talarek, M.; Kacprzyk, R.

    2015-10-01

    Electrostatic discharges from surfaces of plastic materials can be a source of ignition, when appear in explosive atmospheres. Incendivity of electrostatic discharges can be estimated using the transferred charge test. In the case of brush discharges not all the energy stored at the tested sample is released and the effective surface charge density (or surface potential) crater is observed after the discharge. Simplified model, enabling calculation of a charge transferred during electrostatic brush discharge, was presented. Comparison of the results obtained from the simplified model and from direct measurements of transferred charge are presented in the paper.

  10. Loop polymer brushes from polymer single crystals

    Science.gov (United States)

    Zhou, Tian; Li, Christopher

    2014-03-01

    Loop polymer brushes represent a category of polymer brushes with both chain ends being tethered to a surface or interface with sufficiently high density. Due to this morphological difference, loop brushes exhibit distinct properties compared with traditional polymer brushes with single chain end being tethered. In our study, α, ω-functionalized polycaprolactone (PCL) single crystals were prepared as templates for polymer brush synthesis. By carefully controlling crystallization condition and immobilization, looped polymer brushes were successfully prepared. Comprehensive studies on the morphology and physical properties of these polymer brushes were carried out using Atomic Force Microscopy and FTIR. Advantages of using this method include exclusive loop morphology, high grafting density, controlled tethering sites and tunable loop size.

  11. Brush seals and common issues in brush seal applications

    OpenAIRE

    Akşit, Mahmut Faruk; Aksit, Mahmut Faruk

    2012-01-01

    Brush seals are receiving wider acceptance with growing number of successful turbomachinery sealing applications over the past couple of decades. Due to their complaint nature these seals can recover from large transient rotor interference occurrences without any appreciable sustained damage or permanent performance loss. They are formed by a multitude of flexible fine bristles tightly clamped between two metal plates. When subjected to operating pressures and rotor interference, the friction...

  12. Nanotribology of charged polymer brushes

    Science.gov (United States)

    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.

  13. Anomalous Shrinking-Swelling of Nanoconfined End-Charged Polyelectrolyte Brushes: Interplay of Confinement and Electrostatic Effects.

    Science.gov (United States)

    Chen, Guang; Das, Siddhartha

    2016-07-14

    In this article, we model the structure and configuration of the end-charged polyelectrolyte (PE) brushes grafted on the inner walls of a nanochannel. When the confinement effect is weak, that is, d0 electrostatic effects and h is the nanochannel half-height), d electrostatic effects), that is, the brushes shrink due to the electrostatic effects. Furthermore, for this case, an increase in salt concentration increases d. On the contrary, for the case in which the confinement effect is strong (i.e., d0 > h/2), d > d0 (i.e., the electrostatic effects swell the brushes), and an increase in salt concentration decreases the brush height. These findings reveal that the behavior of the end-charged brushes shows three unique differences when compared to that of the standard PE brushes with charges along their entire backbone. These differences are (a) the presence of a distinct role of the confinement in dictating how the electrostatic effects mediated by the electric double layer govern the height of end-charged brushes, (b) electrostatic-effect-driven shrinking of end-charged brushes for d0 electrostatic effects always swell the brushes), and (c) swelling of end-charged brushes with an increase in salt concentration for d0 electrostatics on PE brushes have not been reported previously, and we anticipate that these findings will shed new light on the structure and properties of PE-brush-functionalized nanochannels with implications in applications such as fabrication of functionalized-nanochannel-based nanofluidic diodes, valves, biosensors, current rectifiers, and so forth. PMID:27322913

  14. Comparing the efficiency of Denture brush and Ordinary brush in complete Denture cleaning

    OpenAIRE

    Amir Fayaz; Mohaddeseh Shakerian; Ghassem Ansari

    2013-01-01

    Please cite this article as: Fayaz A, Shakerian M, Ansari GH. Comparing the Efficiency of Denture brush and Ordinary brush in complete Denture cleaning. Novel Biomed 2013;1(2):62-65.Background & objective: Denture cleansing is a key element in retaining mucosa free of any inflammation. However, many denture users usually ignore this important factor. This investigation was designed to compare the efficacy of a denture brush and an ordinary brush in cleansing process of complete dentures.M...

  15. Nanopatterned polymer brushes: conformation, fabrication and applications

    Science.gov (United States)

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

    2015-12-01

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

  16. Dual wound dc brush motor gearhead

    Science.gov (United States)

    Henson, Barrie W.

    1986-01-01

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

  17. Interfacial properties of bottle-brush polyelectrolytes

    DEFF Research Database (Denmark)

    Claesson, P. M.; Naderi, A.; Iruthayaraj, J.; Pettersson, T.; Vareikis, A.; Makuska, R.; Iruthayaraj, Joseph

    This article is focused on interfacial properties of bottle brush polyelectrolytes, where side-chains are attached along a polymer backbone. This class of polymer has been much less studied than block copolymers, which is particularly true for bottle brush polyelectrolytes with a high graft density...

  18. Salt-induced contraction of polyelectrolyte brushes

    International Nuclear Information System (INIS)

    We present an experimental study dedicated to understanding the behaviour of polyelectrolyte chains when salt goes into a polyelectrolyte brush. We use the ability of asymmetric neutral-charged diblock copolymers to anchor to a selective interface or to self-assemble in water, to examine polyelectrolyte brushes both in planar and in spherical geometries. Using neutron reflectivity, the monomer profile of planar brushes has been found to switch from a Gaussian profile to a parabolic profile, showing that at large spatial scale a salted planar brush behaves like a neutral one in good solvent. Using small angle neutron scattering, it is found that spherical brushes exhibit the same behaviour at a large spatial scale although polyelectrolyte chains remain rod-like at a small spatial scale whatever the salinity is. The charged chains inside a polyelectrolyte brush could be viewed as 'surveyor's chains', which fold their rod-like segments of persistence length lp. In the last part, spherical polyelectrolyte brushes in contact have been examined. Their behaviour is discussed in terms of interdigitation or contraction of the brushes

  19. BSA adsorption on bimodal PEO brushes

    NARCIS (Netherlands)

    Bosker, W.T.E.; Iakovlev, P.A.; Norde, W.; Cohen Stuart, M.A.

    2005-01-01

    BSA adsorption onto bimodal PEO brushes at a solid surface was measured using optical reflectometry. Bimodal brushes consist of long (N=770) and short (N=48) PEO chains and were prepared on PS surfaces, applying mixtures of PS 29-PEO48 and PS37-PEO770 block copolymers and using the Langmuir-Blodgett

  20. BSA adsorption on bimodal PEO brushes

    NARCIS (Netherlands)

    Bosker, WTE; Iakovlev, PA; Norde, W; Stuart, MAC

    2005-01-01

    BSA adsorption onto bimodal PEO brushes at a solid surface was measured using optical reflectometry. Bimodal brushes consist of long (N = 770) and short (N = 48) PEO chains and were prepared on PS surfaces, applying mixtures of PS29-PEO48 and PS37-PEO770 block copolymers and using the Langmuir-Blodg

  1. Brush-Wheel Samplers for Planetary Exploration

    Science.gov (United States)

    Rivellini, Tommaso

    2003-01-01

    A report proposes brush-wheel mechanisms for acquiring samples of soils from remote planets. In simplest terms, such a mechanism would contain brush wheels that would be counter-rotated at relatively high speed. The mechanism would be lowered to the ground from a spacecraft or other exploratory vehicle. Upon contact with the ground, the counter-rotating brush wheels would kick soil up into a collection chamber. Thus, in form and function, the mechanism would partly resemble traditional street and carpet sweepers. The main advantage of using of brush wheels (in contradistinction to cutting wheels or other, more complex mechanisms) is that upon encountering soil harder than expected, the brushes could simply deflect and the motor(s) could continue to turn. That is, sufficiently flexible brushes would afford resistance to jamming and to overloading of the motors used to rotate the brushes, and so the motors could be made correspondingly lighter and less power hungry. Of course, one could select the brush stiffnesses and motor torques and speeds for greatest effectiveness in sampling soil of a specific anticipated degree of hardness.

  2. Semiflexible polymer brushes and the brush-mushroom crossover.

    Science.gov (United States)

    Egorov, Sergei A; Hsu, Hsiao-Ping; Milchev, Andrey; Binder, Kurt

    2015-04-01

    Semiflexible polymers end-grafted to a repulsive planar substrate under good solvent conditions are studied by scaling arguments, computer simulations, and self-consistent field theory. Varying the chain length N, persistence length lp, and grafting density σg, the chain linear dimensions and distribution functions of all monomers and of the free chain ends are studied. Particular attention is paid to the limit of very small σg, where the grafted chains behave as "mushrooms" no longer interacting with each other. Unlike a flexible mushroom, which has a self-similar structure from the size (a) of an effective monomer up to the mushroom height (h/a ∝ N(v), ν ≈ 3/5), a semiflexible mushroom (like a free semiflexible chain) exhibits three different scaling regimes, h/a ∝ N for contour length L = Na volume, h/a ∝ (lp/a)(1/5)N(ν). The semiflexible brush is predicted to scale as h/a ∝ (lpaσg)(1/3)N in the excluded volume regime, and h/a ∝ (lpa(3)σ(2))(1/4)N in the Gaussian regime. Since in the volume taken by a semiflexible mushroom excluded-volume interactions are much weaker in comparison to a flexible mushroom, there occurs an additional regime where semiflexible mushrooms overlap without significant chain stretching. Moreover, since the size of a semiflexible mushroom is much larger than the size of a flexible mushroom with the same N, the crossover from mushroom to brush behavior is predicted to take place at much smaller densities than for fully flexible chains. The numerical results, however, confirm the scaling predictions only qualitatively; for chain lengths that are relevant for experiments, often intermediate effective exponents are observed due to extended crossovers. PMID:25687784

  3. PIEZOELECTRIC PROPERTIES OF SINGLE-STRAND DNA MOLECULAR BRUSH BIOLAYERS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The paper is devoted to investigations on nanomechanical behaviors of biochips in label-free biodetections. The chip consists of Si-layer, Ti-layer, Au-layer and single-strand DNA (ssDNA) molecular brush biolayer immobilized by self-assembly technology of thiol group. Unlike previous viewpoints, such as force-bending, entropy-bending and curvature electricity effect, etc.,the piezoelectric effect of the biopolymer brush layer is viewed as the main factor that induces nanomechanical bending of biochips, and a classical macroscopic piezoelectric constitutive relation is used to describe the piezoelectric effect. A new laminated cantilever beam model with a piezoelectric biolayer in continuum mechanics, the linearized Poisson-Boltzmann equation in statistical mechanics and the scaling method in polyelectrolyte brush theory are combined to establish a relationship between the nanomechanical deflection of DNA chips and the factors such as nanoscopic structural features of ssDNA molecules, buffer salt concentration, macroscopic mechanical/piezoelectric parameters of DNA chips etc. Curve fitting of experimental data shows that the sign of the piezoelectric constant of the biolayer may control the deflection direction of DNA chips during the packaging process.

  4. Interfacial Friction and Adhesion of Polymer Brushes

    KAUST Repository

    Landherr, Lucas J. T.

    2011-08-02

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

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

    Science.gov (United States)

    Braun, David; Noon, Don

    1998-01-01

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

  6. Effectiveness of oscillatory gutter brushes in removing street sweeping waste.

    Science.gov (United States)

    Vanegas-Useche, Libardo V; Abdel-Wahab, Magd M; Parker, Graham A

    2015-09-01

    In this paper, the novel concept of oscillatory gutter brushes of road sweepers is studied experimentally. Their effectiveness in removing different debris types is studied by means of a brushing test rig. The debris types dealt with are medium-size gravel, small and fine particles, wet thin debris, and compacted debris. The performance of two types of brushes, cutting and F128, under diverse operating conditions is investigated. The purpose of the tests is to ascertain whether brush oscillations superimposed onto brush rotation improve sweeping effectiveness. According to the results, brush oscillations seem to be useful for increasing brushing effectiveness in the case of bonded particles and wet thin debris, especially for bonded debris, but they seem to be of no value for other loosed debris. Also, appropriate values of brush penetration, sweeper speed, brush angle of attack, rotational speed, and frequency of brush speed oscillations, for the debris types studied are provided. PMID:26026947

  7. Comparing the efficiency of Denture brush and Ordinary brush in complete Denture cleaning

    Directory of Open Access Journals (Sweden)

    Amir Fayaz

    2013-11-01

    Full Text Available Please cite this article as: Fayaz A, Shakerian M, Ansari GH. Comparing the Efficiency of Denture brush and Ordinary brush in complete Denture cleaning. Novel Biomed 2013;1(2:62-65.Background & objective: Denture cleansing is a key element in retaining mucosa free of any inflammation. However, many denture users usually ignore this important factor. This investigation was designed to compare the efficacy of a denture brush and an ordinary brush in cleansing process of complete dentures.Materials & Methods: A group of 31 individuals aged 44-76 years were included in this study. Each patient was then instructed to use the denture brush for a period of 4 weeks while an ordinary brush was to be used for the following 4 weeks. Dentures were photographed and evaluated at every two week intervals using a computer photographic software assessment method. Pictures were compared using the image tool for plaque remaining on the denture surfaces. Student t-test was used to analyse data collected.Results: Comparison of the brush type efficacy at 2 and 4 weeks did not show any significant difference ( P>0.05 , however , clinical evaluation indicated that denture brush leaves much less plaque bio-film compare to the ordinary one, with mean plaque traced at 6.88 to 9.24 in 4 weeks.Conclusion: There were no significant differences found between the two brushes’ efficacy, with clinical evaluation significantly in favor of denture brush.

  8. Gingival abrasion and plaque removal with manual versus electric toothbrushing.

    Science.gov (United States)

    Niemi, M L; Ainamo, J; Etemadzadeh, H

    1986-08-01

    A clinical trial was designed to test the relative numbers of gingival lesions caused during standardized brushing of the teeth of 22 volunteer dental nurse students with a manual soft multitufted, a manual soft V-shaped, and an electric toothbrush. First, the left or the right side of the jaws of each subject was brushed by a dental hygienist using the manual V-shaped or the electric brush, and the other side using the manual multitufted brush. At the 2nd brushing 1 week later, the same hygienist used the multitufted brush for brushing the side contralateral to the one in which it was used the 1st week and the V-shaped manual brush instead of the electric and vice versa. After each brushing, the number of new gingival lesions was recorded and the cleansing effect evaluated by assessment of the amount of remaining plaque. This examiner was unaware of the type of brush used. The V-shaped manual toothbrush was found to have caused more gingival abrasion than the electric toothbrush (P less than 0.005) and a similar difference was found between the multitufted manual and the electric toothbrush (P less than 0.05). There was no clinically significant difference between the plaque removing effects of the 3 brushes tested. PMID:3463575

  9. Motor Brush Testing for Mars and Vacuum

    Science.gov (United States)

    Noon, Don E.

    1999-01-01

    Brush motors have been qualified and flown successfully on Mars missions, but upcoming missions require longer life and higher power. A test program was therefore undertaken to identify the best brush material for operation in the Mars atmosphere. Six different brush materials were used in 18 identical motors and operated under various load conditions for a period of four weeks in low-pressure CO2. All motors performed acceptably, with accumulated motor revolutions between 98 and 144 million revolutions, depending on load. A proprietary silver-graphite material from Superior Carbon (SG54-27) appears to be the best choice for long life, but even the stock copper-graphite brushes performed reliably with acceptable wear. The motors from the CO2 test were then cleaned and run in vacuum for 2 weeks. The difference in results was dramatic, with 5 motors failing catastrophically and wear rates increasing by orders of magnitude for the SG54-27 material. Three brush materials survived the test with no failures: SG54-27 with a proprietary Ball Aerospace impregnation, a silver-graphite-molybdenum disulfide material from Superior Carbon (SG59), and a copper sulfide-graphite material also from Superior Carbon (BG91).

  10. Dimeric assembly of enterocyte brush border enzymes

    DEFF Research Database (Denmark)

    Danielsen, E M

    1994-01-01

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

  11. Phototriggered functionalization of hierarchically structured polymer brushes.

    Science.gov (United States)

    de los Santos Pereira, Andres; Kostina, Nina Yu; Bruns, Michael; Rodriguez-Emmenegger, Cesar; Barner-Kowollik, Christopher

    2015-06-01

    The precise design of bioactive surfaces, essential for the advancement of many biomedical applications, depends on achieving control of the surface architecture as well as on the ability to attach bioreceptors to antifouling surfaces. Herein, we report a facile avenue toward hierarchically structured antifouling polymer brushes of oligo(ethylene glycol) methacrylates via surface-initiated atom transfer radical polymerization (SI-ATRP) presenting photoactive tetrazole moieties, which permitted their functionalization via nitrile imine-mediated tetrazole-ene cyclocloaddition (NITEC). A maleimide-functional ATRP initiator was photoclicked to the side chains of a brush enabling a subsequent polymerization of carboxybetaine acrylamide to generate a micropatterned graft-on-graft polymer architecture as evidenced by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Furthermore, the spatially resolved biofunctionalization of the tetrazole-presenting brushes was accessed by the photoligation of biotin-maleimide and subsequent binding of streptavidin. The functionalized brushes bearing streptavidin were able to resist the fouling from blood plasma (90% reduction with respect to bare gold). Moreover, they were employed to demonstrate a model biosensor by immobilization of a biotinylated antibody and subsequent capture of an antigen as monitored in real time by surface plasmon resonance. PMID:25961109

  12. Curvature elasticity of a grafted polyelectrolyte brush

    Science.gov (United States)

    Lei, Zhen; Miao, Bing; Yang, Shuang; Chen, Er-Qiang

    2015-06-01

    The curvature elasticity of a polyelectrolyte brush monolayer attached to curved surface is investigated theoretically. An analytical method based on the strong-stretching theory for a Gaussian chain is developed to calculate the elastic modulus induced by a polyelectrolyte brush. In particular, the scaling relations for the bending or Gaussian modulus with respect to system parameters related to the electrostatic interaction (degree of ionization and salt concentration) are derived. Using the numerical self-consistent-field theory, the inner structural, free-energy, and elastic moduli are computed for the polyelectrolyte brush with excluded-volume interactions. Compared to the analytical result, the curvature elasticity has a weaker dependence on the system parameters, which is attributed to the linearization for the Poisson-Boltzmann equation in the analytical treatment. Furthermore, our results are compared to the curvature elasticity of a bare charged surface, wherefrom the unique polyelectrolyte brush effect on the surface elasticity is clarified clearly. The scaling relations derived in our paper can serve as a guide to experimental studies on the related systems.

  13. Spherical Polyelectrolyte Brushes and Their Films

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Nano-sized spherical polyelectrolyte brushes (SPB), which consist of a solid polystyrene core and linear poly(acrylic acid) (PAA) chains covalently attached on the core surface by one end with different lengths and grafting densities, were prepared by photo-emulsion polymerization and thermo- controlled emulsion polymerization.

  14. Chinese Brush Calligraphy Character Retrieval and Learning

    Science.gov (United States)

    Zhuang, Yueting; Zhang, Xiafen; Lu, Weiming; Wu, Fei

    2007-01-01

    Chinese brush calligraphy is a valuable civilization legacy and a high art of scholarship. It is still popular in Chinese banners, newspaper mastheads, university names, and celebration gifts. There are Web sites that try to help people enjoy and learn Chinese calligraphy. However, there lacks advanced services such as content-based retrieval or…

  15. Conjugated Polymer Brushes (Poly(3-hexylthiophene) brushes): new electro- and photo-active molecular architectures

    OpenAIRE

    Khanduyeva, Natalya

    2009-01-01

    The aim of the present work was to screen the main methods for the synthesis of conjugated polymers for their suitability in the preparation of conductive polymer brushes. The main focus was put on the grafting of intrinsically soluble substituted regioregular polyalkylthiophenes because of their excellent optoelectronic properties. The resulting polymer films were characterized and their optoelectrical properties studied. For the first time, a synthesis of conductive polymer brushes on solid...

  16. Electric drives

    CERN Document Server

    Boldea, Ion

    2005-01-01

    ENERGY CONVERSION IN ELECTRIC DRIVESElectric Drives: A DefinitionApplication Range of Electric DrivesEnergy Savings Pay Off RapidlyGlobal Energy Savings Through PEC DrivesMotor/Mechanical Load MatchMotion/Time Profile MatchLoad Dynamics and StabilityMultiquadrant OperationPerformance IndexesProblemsELECTRIC MOTORS FOR DRIVESElectric Drives: A Typical ConfigurationElectric Motors for DrivesDC Brush MotorsConventional AC MotorsPower Electronic Converter Dependent MotorsEnergy Conversion in Electric Motors/GeneratorsPOWER ELECTRONIC CONVERTERS (PECs) FOR DRIVESPower Electronic Switches (PESs)The

  17. Synthesis and characterization of metal oxide nanorod brushes

    Indian Academy of Sciences (India)

    Kalyan Raidongia; M Eswaramoorthy

    2008-02-01

    Nanorod brushes of -Al2O3, MoO3 and ZnO have been synthesized using amorphous carbon nanotube (-CNT) brushes as the starting material. The brushes of -Al2O3 and MoO3 are made up of single crystalline nanorods. In the case of ZnO brushes, the nanorod bristles are made by the fusion of 15–25 nm size nanoparticles and are porous in nature. Metal oxide nanorod brushes thus obtained have been characterized by XRD, FESEM, TEM and Raman spectroscopy. Single crystalline ruby nanorods were obtained by introducing chromium ions during the synthesis of alumina rods.

  18. Fouling-resistant polymer brush coatings

    KAUST Repository

    Thérien-Aubin, Héloïse

    2011-11-01

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

  19. Novel Hyperbranched Polyurethane Brushes for Biomedical Applications

    Institute of Scientific and Technical Information of China (English)

    Ton; Loontjens; Bart; Plum

    2007-01-01

    1 Results The objective was to make hyperbranched (HB) polyurethane brushes with reactive end groups, to coat biomedical devices and to enable the introduction of various functionalities that are needed to fulfill biomedical tasks.Biomedical materials should fulfill at least three requirements: (1) good mechanical properties, (2) good biocompatibility and (3) provided with functionalities to perform the required tasks. Since polyurethanes are able to fulfill the first 2 requirements we focused in this w...

  20. Antifouling polymer brushes displaying antithrombogenic surface properties

    Czech Academy of Sciences Publication Activity Database

    de los Santos Pereira, Andres; Sheikh, S.; Blaszykowski, C.; Pop-Georgievski, Ognen; Fedorov, K.; Thompson, M.; Rodriguez-Emmenegger, Cesar

    2016-01-01

    Roč. 17, č. 3 (2016), s. 1179-1185. ISSN 1525-7797 R&D Projects: GA ČR(CZ) GJ15-09368Y; GA MŠk(CZ) ED1.1.00/02.0109 Grant ostatní: OPPK(XE) CZ.2.16/3.1.00/21545 Institutional support: RVO:61389013 Keywords : polymer brushes * surface characterization * antifouling surfaces Subject RIV: BO - Biophysics Impact factor: 5.750, year: 2014

  1. Phototriggered functionalization of hierarchically structured polymer brushes

    Czech Academy of Sciences Publication Activity Database

    de los Santos Pereira, Andres; Kostina, Nina Yu.; Bruns, M.; Rodriguez-Emmenegger, Cesar; Barner-Kowollik, C.

    2015-01-01

    Roč. 31, č. 21 (2015), s. 5899-5907. ISSN 0743-7463 R&D Projects: GA ČR(CZ) GJ15-09368Y; GA MŠk(CZ) ED1.1.00/02.0109 Grant ostatní: OPPK(XE) CZ.2.16/3.1.00/21545 Institutional support: RVO:61389013 Keywords : polymer brushes * antifouling * click chemistry Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.457, year: 2014

  2. Hierarchical antifouling brushes for biosensing applications

    Czech Academy of Sciences Publication Activity Database

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

    2014-01-01

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

  3. Optical brush: Imaging through permuted probes

    Science.gov (United States)

    Heshmat, Barmak; Lee, Ik Hyun; Raskar, Ramesh

    2016-02-01

    The combination of computational techniques and ultrafast imaging have enabled sensing through unconventional settings such as around corners, and through diffusive media. We exploit time of flight (ToF) measurements to enable a flexible interface for imaging through permuted set of fibers. The fibers are randomly distributed in the scene and are packed on the camera end, thus making a brush-like structure. The scene is illuminated by two off-axis optical pulses. Temporal signatures of fiber tips in the scene are used to localize each fiber. Finally, by combining the position and measured intensity of each fiber, the original input is reconstructed. Unlike conventional fiber bundles with packed set of fibers that are limited by a narrow field of view (FOV), lack of flexibility, and extended coaxial precalibration, the proposed optical brush is flexible and uses off-axis calibration method based on ToF. The enabled brush form can couple to other types of ToF imaging systems. This can impact probe-based applications such as, endoscopy, tomography, and industrial imaging and sensing.

  4. Antifouling Polymer Brushes Displaying Antithrombogenic Surface Properties.

    Science.gov (United States)

    de Los Santos Pereira, Andres; Sheikh, Sonia; Blaszykowski, Christophe; Pop-Georgievski, Ognen; Fedorov, Kiril; Thompson, Michael; Rodriguez-Emmenegger, Cesar

    2016-03-14

    The contact of blood with artificial materials generally leads to immediate protein adsorption (fouling), which mediates subsequent biological processes such as platelet adhesion and activation leading to thrombosis. Recent progress in the preparation of surfaces able to prevent protein fouling offers a potential avenue to mitigate this undesirable effect. In the present contribution, we have prepared several types of state-of-the-art antifouling polymer brushes on polycarbonate plastic substrate, and investigated their ability to prevent platelet adhesion and thrombus formation under dynamic flow conditions using human blood. Moreover, we compared the ability of such brushes-grafted on quartz via an adlayer analogous to that used on polycarbonate-to prevent protein adsorption from human blood plasma, assessed for the first time by means of an ultrahigh frequency acoustic wave sensor. Results show that the prevention of such a phenomenon constitutes one promising route toward enhanced resistance to thrombus formation, and suggest that antifouling polymer brushes could be of service in biomedical applications requiring extensive blood-material surface contact. PMID:26882214

  5. Pancreaticobiliary Tuberculosis Diagnosed by Endoscopic Brushings

    Directory of Open Access Journals (Sweden)

    Atul Sachdev

    2006-11-01

    Full Text Available Context Isolated pancreaticobiliaryinvolvement with tuberculosis is extremely unusual. Clinical manifestations includeabdominal discomfort, weight loss, obstructive jaundice or pancreatitis. Mass/ cystic lesions are seen on imaging studies and are often mistaken for pancreatic malignancy. Diagnosis is by demonstration of caseation necrosis or the presence of acid-fast bacilli on Ziehl Neelson staining in the aspirated or biopsied specimen.Case report A 35-year-old man presented with pain in the upper abdomen of two-month duration associated with significant weight loss. Investigation showed elevated alkaline phosphatase. Imaging studies revealed a mass in the region of the head of the pancreas with dilated intra-hepatic biliary radicles. The diagnosis of pancreaticobiliary tuberculosis was confirmed by cytology from biliary brushing. Biliary brushings taken during endoscopic retrograde cholangiopancreatography have never previously confirmed the diagnosis of pancreaticobiliary tuberculosis.Conclusions To the best of our knowledge, this is the first case report where the diagnosis was made on the basis of biliary brushings.

  6. New propulsion components for electric vehicles

    Science.gov (United States)

    Secunde, R. R.

    1983-01-01

    Improved component technology is described. This includes electronically commutated permanent magnet motors of both drum and disk configurations, an unconventional brush commutated motor, ac induction motors, various controllers, transmissions and complete systems. One or more of these approaches to electric vehicle propulsion may eventually displace presently used controllers and brush commutated dc motors. Previously announced in STAR as N83-25982

  7. Polymer-brush lubrication: a review of recent theoretical advances.

    Science.gov (United States)

    Kreer, T

    2016-04-13

    This review compiles recent theoretical advances to describe compressive and shear forces of polymer-brush bilayers, which consist of two opposing brushes in contact. Such model systems for polymer-brush lubrication are frequently used as a benchmark to gain insight into biological problems, e.g., synovial joint lubrication. Based on scaling theory, I derive conformational and collective properties of polymer-brush bilayers in equilibrium and out-of-equilibrium situations, such as shear forces in the linear and nonlinear response regimes of stationary shear and under non-stationary shear. Furthermore, I discuss the influence of macromolecular inclusions and electrostatic interactions on polymer-brush lubrication. Comparisons to alternative analytical approaches, experiments and numerical results are performed. Special emphasis is given to methods for simulating polymer-brush bilayers using molecular dynamics simulations. PMID:27029521

  8. Non-metallic brush seals for gas turbine bearings

    OpenAIRE

    Bhate, Nitin; Thermos, Anthony C.; Akşit, Mahmut Faruk; Aksit, Mahmut Faruk; Demiroğlu, Mehmet; Demiroglu, Mehmet; Kizil, Huseyin

    2004-01-01

    A non-metallic brush seal has been developed as an oil seal for use in turbomachinary. Traditionally labyrinth-type seals with larger clearances have been used in such applications. Labyrinth seals have higher leakage rates and can undergo excessive wear in case of rotor instability. Brush seals reduce leakage by up to an order of magnitude and provide compliance against rotor instabilities. Brush seals are compact and are much less prone to degradation associated with oil sealing. This pa...

  9. Entanglements of End Grafted Polymer Brushes in a Polymeric Matrix

    Science.gov (United States)

    Grest, Gary S.; Hoy, Robert S.

    2007-03-01

    The entanglement of a polymer brush immersed in a melt of mobile polymer chains is studied by molecular dynamics simulations. A primitive path analysis (PPA) is carried out to identify the brush/brush, brush/melt and melt/melt entanglements as a function of distance from the substrate. The PPA characterizes the microscopic state of conformations of the polymer chain and is ideally suited to identify chain/chain entanglements. We use a new thin-chain PPA technique to eliminate spurious non-entangled inter chain contacts arising from excluded volume. As the grafting density of the brush increases we find that the entanglements of the brush with the melt decrease as the system crosses over from the wet to dry brush regime. Results are compared to brush/brush entanglements in an implicit solvent of varying solvent quality. Sandia is a multiprogram laboratory operated by Sandia Corp., a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  10. REGIONAL COST SHARE NECESSARY FOR RANCHER PARTICIPATION IN BRUSH CONTROL

    OpenAIRE

    Lee, A.; Conner, J.; Mjelde, J.; Richardson, J; Stuth, J

    2001-01-01

    Large-scale brush-control programs are being proposed in Texas to increase off-site water yields. Biophysical and economic simulation models are combined to estimate the effects of brush control on representative ranches in four ecological regions of the Edwards Plateau area of Texas. Net present values of representative ranches in three of four regions decrease with brush control. Cost shares necessary for ranches from the three regions to break even range from 7% to 31% of total brush-contr...

  11. EFFICACY OF BIOFILM DISCLOSING AGENT AND OF THREE BRUSHES IN THE CONTROL OF COMPLETE DENTURE CLEANSING

    OpenAIRE

    Cláudia Helena Lovato da Silva; Helena de Freitas Oliveira Paranhos

    2006-01-01

    OBJECTIVE: This report evaluated the efficacy of three brushes and one biofilm disclosing agent in complete denture cleansing. METHODS: Twenty-seven wearers of maxillary dentures were distributed into three groups and received different brushes: Oral B40, conventional toothbrush (Oral B); Denture, denture-specific brush (Condor); Johnson & Johnson, denture-specific brush (Johnson & Johnson). The 60-day experimental period was divided into two techniques: I - brushing (brush associated with a ...

  12. An anionic spherical polyelectrolyte brushes-driven approach to synthesize conductive composites

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yu; Zhan, Zhan [Wuhan University, School of Printing and Packaging (China); Zhang, Xiongzhi [Wuhan University, College of Chemistry and Molecular Sciences (China); Li, Houbin, E-mail: lhb@whu.edu.cn [Wuhan University, School of Printing and Packaging (China); Huang, Chi [Wuhan University, College of Chemistry and Molecular Sciences (China)

    2015-08-15

    The composites of anionic spherical polyelectrolyte brushes/conducing polymer (ASPB/CP) have been successfully prepared by chemical oxidative polymerization of aniline and pyrrole monomers in an acidic medium containing anionic spherical polyelectrolyte brushes. These composites were characterized by field emission scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectrometry, zeta potentials, X-ray photoelectron spectroscopy, and four probe methods. It was found that the poly(aniline-co-pyrrole) was uniformly coated on the surface of ASPB. Besides, the ASPB/CP composites had higher doping level than the pure copolymer after doping with ASPB. Moreover, these composites also showed better solubility and storage stability than pure copolymer. The electrical conductivity of the ASPB/CP composites at room temperature was 7.2 S/cm, while it was 2.4 S/cm for the pure copolymer under the same circumstances.

  13. Conformational properties of bottle-brush polymers

    Science.gov (United States)

    Denesyuk, N. A.

    2003-05-01

    General and renormalized perturbation theories are used to study the conformational properties of a bottle-brush molecule, composed of multiarmed polymer stars grafted regularly onto a flexible backbone. The end-to-end distances of the backbone and of an arm of the middle star are calculated within the first order of perturbation theory. For the high grafting densities of stars, the calculated expressions are generalized with the help of the scaling arguments to give the equivalent power laws. According to these laws, the molecule may adopt a sequence of three different conformations (star-rod-coil) as the length of the backbone grows.

  14. Conformational properties of bottle-brush polymers.

    Science.gov (United States)

    Denesyuk, N A

    2003-05-01

    General and renormalized perturbation theories are used to study the conformational properties of a bottle-brush molecule, composed of multiarmed polymer stars grafted regularly onto a flexible backbone. The end-to-end distances of the backbone and of an arm of the middle star are calculated within the first order of perturbation theory. For the high grafting densities of stars, the calculated expressions are generalized with the help of the scaling arguments to give the equivalent power laws. According to these laws, the molecule may adopt a sequence of three different conformations (star-rod-coil) as the length of the backbone grows. PMID:12786171

  15. Monte Carlo simulation of block copolymer brushes

    International Nuclear Information System (INIS)

    We studied a simplified model of a polymer brush formed by linear chains, which were restricted to a simple cubic lattice. The chain macromolecules consisted of a sequence of two kinds of segment, arranged in a specific sequence. The chains were grafted to an impenetrable surface, i.e. they were terminally attached to the surface at one end. The number of chains was varied from low to high grafting density. The model system was studied under different solvent quality, from good to poor solvent. The properties of this model system were studied by means of Monte Carlo simulations. The sampling algorithm was based on local changes of the chain's conformations

  16. In vitro tooth cleaning efficacy of electric toothbrushes around brackets

    OpenAIRE

    Schätzle, M; Sener, B.; Schmidlin, P.R; Imfeld, T; Attin, T.

    2010-01-01

    This in vitro study assessed the cleaning efficacy of different electric toothbrushes around upper incisor brackets. Standard and Mini Diamond™ brackets were fixed on black-stained teeth. The teeth were coated with white titanium oxide and brushed in a machine twice for 1 minute each. Twelve different brush heads with either a wiping or an oscillating-rotating action were tested. After brushing, the teeth were scanned, the black surfaces were assessed planimetrically and a modified plaque ind...

  17. 16 CFR Figure 8 to Part 1610 - Brush

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Brush 8 Figure 8 to Part 1610 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FLAMMABLE FABRICS ACT REGULATIONS STANDARD FOR THE FLAMMABILITY OF CLOTHING TEXTILES Pt.1610, Fig. 8 Figure 8 to Part 1610—Brush ER25MR08.007...

  18. Nanopatterned polymer brushes by reactive writing

    Science.gov (United States)

    Nawroth, Jonas F.; Neisser, Claudia; Erbe, Artur; Jordan, Rainer

    2016-03-01

    Polymer brush patterns were prepared by a combination of electron beam induced damage in self-assembled monolayers (SAMs), creating a stable carbonaceous deposit, and consecutive self-initiated photografting and photopolymerization (SIPGP). This newly applied technique, reactive writing (RW), is investigated with 1H,1H,2H,2H-perfluorooctyltriethoxysilane SAM (PF-SAM) on silicon oxide, which, when modified by RW, can be selectively functionalized by SIPGP. With the monomer N,N-dimethylaminoethyl methacrylate (DMAEMA), we demonstrate the straightforward formation of polymer brush gradients and single polymer lines of sub-100 nm lateral dimensions, with high contrast to the PF-SAM background. The lithography parameters acceleration voltage, irradiation dose, beam current and dwell time were systematically varied to identify the optimal conditions for the maximum conversion of the SAM into a carbonaceous deposit. The results of this approach were compared to patterns prepared by carbon templating (CT) under analogous conditions, revealing a dwell time dependency, which differs from earlier reports. This new technique expands the range of CT by giving the opportunity to not only vary the chemistry of the created polymer patterns with monomer choice but also vary the chemistry of the surrounding substrate.

  19. Virtual hairy brush for digital painting and calligraphy

    Institute of Scientific and Technical Information of China (English)

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

    2005-01-01

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

  20. 75 FR 34097 - Natural Bristle Paint Brushes and Brush Heads From the People's Republic of China: Notice of...

    Science.gov (United States)

    2010-06-16

    ... Results of Antidumping Duty Changed Circumstances Review and Intent Not to Revoke, In Part, 73 FR 60214... Brushes and Paint Brush Heads from the People's Republic of China, 51 FR 5580 (Feb. 14, 1986) and Amended... China, 51 FR 8342 (March 11, 1986) (``Order''). The domestic industry submitted a letter to...

  1. Study of Hardness and Electrical Properties of Prepared

    OpenAIRE

    Mohammed I. Mohammed; Raheek I. Ibrahim

    2013-01-01

    In electric motors, electrical energy is transformed to mechanical energy or vice versa. Electrical energy has to be transformed from a stationary component into moving one, which is done by  copper commentator in sliding  contact with graphite brushes.       This study includes  a technical  method to prepare metal – graphite  composite brushes. The prepared brushes are tested and found to have mechanical and electrical properties agree with standards.

  2. A norbornene polymer brush for electro-optic applications

    International Nuclear Information System (INIS)

    Norbornene-dicarboximide derived polymer brushes containing Disperse Red 1 appended chromophores have been prepared by sequencial ring opening metathesis polymerization and atom transfer radical polymerization. This brush was then employed as an electro-optic polymer host for high molecular hyperpolarizability phenyl vinylene thiophene vinylene (FTC) bridge chromophores in a binary chromophore system. The r33 of the polymer brush/bi-chromophore network was evaluated via in situ poling and was measured as 94 pm/V compared to the benchmark polymethylmethacrylate (PMMA) system of 76 pm/V with an identical chromophore. Furthermore, our polymer brush/bi-chromophore network exhibited an enhanced poling efficiency of 1.37 (nm/V)2 as compared to a simple PMMA - FTC host - guest 0.70 (nm/V)2. - Highlights: • Synthesis of a norbornene polymer brush. • Use of this polymer brush as a host for electro-optic materials. • The polymer brush enables a large electro-optic coefficient r33

  3. A norbornene polymer brush for electro-optic applications

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Yue; Spring, Andrew M.; Yu, Feng; Yamamoto, Kazuhiro [Institute for Materials Chemistry and Engineering, Kyushu University, 6–1 Kasuga Fukuoka 816–8580 (Japan); Aoki, Isao; Otomo, Akira [National Institute of Information and Communications Technology, 588–2 Iwaoka, Nishi-ku, Kobe 651–2492 (Japan); Yokoyama, Shiyoshi, E-mail: s_yokoyama@cm.kyushu-u.ac.jp [Institute for Materials Chemistry and Engineering, Kyushu University, 6–1 Kasuga Fukuoka 816–8580 (Japan)

    2014-03-03

    Norbornene-dicarboximide derived polymer brushes containing Disperse Red 1 appended chromophores have been prepared by sequencial ring opening metathesis polymerization and atom transfer radical polymerization. This brush was then employed as an electro-optic polymer host for high molecular hyperpolarizability phenyl vinylene thiophene vinylene (FTC) bridge chromophores in a binary chromophore system. The r{sub 33} of the polymer brush/bi-chromophore network was evaluated via in situ poling and was measured as 94 pm/V compared to the benchmark polymethylmethacrylate (PMMA) system of 76 pm/V with an identical chromophore. Furthermore, our polymer brush/bi-chromophore network exhibited an enhanced poling efficiency of 1.37 (nm/V){sup 2} as compared to a simple PMMA - FTC host - guest 0.70 (nm/V){sup 2}. - Highlights: • Synthesis of a norbornene polymer brush. • Use of this polymer brush as a host for electro-optic materials. • The polymer brush enables a large electro-optic coefficient r{sub 33}.

  4. Effectiveness of gutter brushes in removing street sweeping waste.

    Science.gov (United States)

    Vanegas Useche, Libardo V; Wahab, Magd M Abdel; Parker, Graham A

    2010-02-01

    Litter on roadways has to be removed for hygiene and to reduce pollution, amongst other reasons. Therefore, the effective operation of street sweepers is important in the collection of solid waste. In this article, the effectiveness of gutter brushes of street sweepers in removing different debris types, namely medium-size gravel, small and fine particles, and wet thin debris is studied by means of sweeping tests using a brushing test rig. Two types of gutter brushes, cutting and F128, are tested under a variety of operating conditions. The experimental tests provide a means of identifying suitable ranges of brush penetration for the different debris types under defined operating parameters such as brush angle of attack, brush rotational speed, and sweeper velocity. These ranges may provide sufficiently high removal forces and avoid the occurrence of sweeping problems such as backward sweeping and inappropriate bristle-surface contact. Optimum operating parameters for the three debris types studied, as well as a mixture of all of them, are determined. Lastly, the results indicate that, as far as the sweeping effectiveness is concerned, the F128 brush is the preferred one for the cases studied. PMID:19879125

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

    Directory of Open Access Journals (Sweden)

    Fresia Canales Carmona

    2013-10-01

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

  6. Materials evaluation for use as plasma brush electrodes with hybrid armatures

    Energy Technology Data Exchange (ETDEWEB)

    Hawke, R.S.; Morrison, J.J.; Susoeff, A.R. [Lawrence Livermore National Lab., CA (United States)

    1995-01-01

    There is a strong motivation to develop a railgun armature which will function as a non-arc, solid contact armature throughout the complete projectile acceleration to launch process. Solid contact armatures are more efficient in converting electrical to kinetic energy and generally cause less erosion of the rail. Considerable effort is being directed towards designing armatures capable of reaching 3+km/s while avoiding transition from a solid to an arcing contact. While nearly 2 km/s has been achieved in a non-arcing contact, it may be inevitable that an arcing contact will be unavoidable during the final acceleration to full desired velocities. At present most solid armatures are fabricated from aluminum or copper. While aluminum or copper might be good choices for solid contacts, this paper introduces the possibility that a different material will better serve as an electrode in an arcing contact. For example upon transition, the conduction of current through a plasma brush results in rapid erosion of aluminum armatures. When transition to an arcing contact occurs, the authors have found that magnetic pressure can be used to minimize the length of the plasma brush, which helps minimize the mass of the armature and improves the overall efficiency of energy transfer to the projectile payload. However, short length brushes result in high current density, and high erosion rates. The authors have measured the erosion of aluminum surfaces when used as a cathode and as an anode while magnetically containing the brushes. They have also measured the erosion of a thoriated tungsten (W-Th) cathode when used in the same manner. The erosion of the W-Th was more about a factor of 11 less than the A{ell}. This paper presents these results and a discussion of electron emission for Al, Cu, W and W-Th.

  7. Macroion Interaction at Polyelectrolyte Brush Interfaces

    Science.gov (United States)

    Qu, Chen

    2015-03-01

    The effect of macroions, including synthetic polyelectrolytes, DNA and proteins, on the structure and surface properties of charged polymer thin films remains inadequately understood partially due to the complexity involving the hydrophobic effect and the conformational change of polymeric macroions. In this work, we explore a group of inorganic nanocluster based macroions, hydrophilic polyoxometalates (POMs) of robust nanocluster structure and carrying high surface charges (~ 2-42 negative charges) to investigate their interaction with surface tethered poly-2-vinylpyridine (P2VP) brush-like thin films immersed in aqueous solution. We observe the collapse of swollen P2VP chains by adding POM macroions of increased concentration by AFM, QCM and contact goniometer measurements, in sharp contrast to the increased chain stretching by adding monovalent salts. A careful comparison is made between distinct POMs based on their charge, size and chemical nature. These findings serve as a good reference for theoretical model modification and design of new mesoporous composite membranes.

  8. Sterilization effects of atmospheric cold plasma brush

    International Nuclear Information System (INIS)

    This study investigated the sterilization effects of a brush-shaped plasma created at one atmospheric pressure. A population of 1.0x104-1.0x105 Escherichia coli or Micrococcus luteus bacteria was seeded in filter paper media and then subjected to Ar and/or Ar+O2 plasmas. A complete kill of the Micrococcus luteus required about 3 min argon plasma exposures. With oxygen addition into the argon plasma gas streams, a complete kill of the bacteria needed only less than 1 min plasma exposure for Micrococcus luteus and about 2 min exposure for Escherichia coli. The plasma treatment effects on the different bacteria cell structures were examined using scanning electron microscopy

  9. Control of Electric Vehicle

    OpenAIRE

    Huang, Qi; Chen, Yong; Li, Jian

    2010-01-01

    In this chapter, the modeling of electric vehicle is discussed in detail. Then, the control of electric vehicle driven by different motors is discussed. Both brushed and brushless DC (Direct Current) motors are discussed. And for AC (Alternative Current) motors, the discussion is focused on induction motor and permanent magnet synchronous motor. The design of controllers for different motor-driven electric vehicle is discussed in-depth, and the tested high-performance control strategies for d...

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

    DEFF Research Database (Denmark)

    Bast, L. S.; Nordahl, H.; Christensen, L. B.;

    2015-01-01

    OBJECTIVE: Regular tooth brushing in adolescence predicts stable tooth brushing habits later in life. Differences in tooth brushing habits by ethnic background and socioeconomic position have been suggested. We investigated migration status and social class in relation to infrequent tooth brushing...

  11. Brushes and soap : Grafted polymers and their interactions with nanocolloids

    OpenAIRE

    Currie, E.P.K.

    2000-01-01

    Layers of polymer chains end-attached to a grafting plane at high densities, so-called brushes, are a curious state of matter. The (average) monomer density within the brush is as high as in a semi-dilute polymer solution, resulting in a high osmotic pressure in the brush. Due to the grafting, however, this isotropic osmotic pressure results in an anisotropic stretching of the chains normal to the surface. This degree of stretching can be quite extensive; in this thesis PEO-chains of 700 mono...

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

    DEFF Research Database (Denmark)

    Chernyy, Sergey; Järn, Mikael; Shimizu, Kyoko;

    2014-01-01

    This work demonstrates the feasibility of superhydrophilic polyelectrolyte brush coatings for anti-icing applications. Five different types of ionic and nonionic polymer brush coatings of 25-100 nm thickness were formed on glass substrates using silane chemistry for surface premodification followed...... by polymerization via the SI-ATRP route. The cationic [2-(methacryloyloxy)ethyl]trimethylammonium chloride] and the anionic [poly(3-sulfopropyl methacrylate), poly(sodium methacrylate)] polyelectrolyte brushes were further exchanged with H(+), Li(+), Na(+), K(+), Ag(+), Ca(2+), La(3+), C16N(+), F......(-), Cl(-), BF4(-), SO4(2-), and C12SO3(-) ions. By consecutive measurements of the strength of ice adhesion toward ion-incorporated polymer brushes on glass it was found that Li(+) ions reduce ice adhesion by 40% at -18 °C and 70% at -10 °C. Ag(+) ions reduce ice adhesion by 80% at -10 °C relative to...

  13. Surface wave excitations and backflow effect over dense polymer brushes

    Science.gov (United States)

    Biagi, Sofia; Rovigatti, Lorenzo; Sciortino, Francesco; Misbah, Chaouqi

    2016-03-01

    Polymer brushes are being increasingly used to tailor surface physicochemistry for diverse applications such as wetting, adhesion of biological objects, implantable devices and much more. Here we perform Dissipative Particle Dynamics simulations to study the behaviour of dense polymer brushes under flow in a slit-pore channel. We discover that the system displays flow inversion at the brush interface for several disconnected ranges of the imposed flow. We associate such phenomenon to collective polymer dynamics: a wave propagating on the brush surface. The relation between the wavelength, the amplitude and the propagation speed of the flow-generated wave is consistent with the solution of the Stokes equations when an imposed traveling wave is assumed as the boundary condition (the famous Taylor’s swimmer).

  14. Surface wave excitations and backflow effect over dense polymer brushes.

    Science.gov (United States)

    Biagi, Sofia; Rovigatti, Lorenzo; Sciortino, Francesco; Misbah, Chaouqi

    2016-01-01

    Polymer brushes are being increasingly used to tailor surface physicochemistry for diverse applications such as wetting, adhesion of biological objects, implantable devices and much more. Here we perform Dissipative Particle Dynamics simulations to study the behaviour of dense polymer brushes under flow in a slit-pore channel. We discover that the system displays flow inversion at the brush interface for several disconnected ranges of the imposed flow. We associate such phenomenon to collective polymer dynamics: a wave propagating on the brush surface. The relation between the wavelength, the amplitude and the propagation speed of the flow-generated wave is consistent with the solution of the Stokes equations when an imposed traveling wave is assumed as the boundary condition (the famous Taylor's swimmer). PMID:26975329

  15. Efficient polymer solar cells fabricated by simple brush painting

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S.S.; Na, S.I.; Jo, J.; Tae, G.; Kim, D.Y. [Heeger Center for Advanced Materials, Department of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju (Korea)

    2007-12-17

    We demonstrate a brushing technique as a promising method for the mass production of efficient and flexible solar cells even on a non-flat surface such as roofing tiles. Higher device efficiency could be obtained compared to the spin-coated devices, resulting from the improved organization of polymer chains and domains induced by more effective application of shear stress to the polymer chains during the brushing process. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  16. Role of gastric brush cytology in the diagnosis of giardiasis

    OpenAIRE

    Varma Deepali; Jain Shyama; Khurana Nita

    2008-01-01

    Background: Giardiasis, common in developing countries, has mostly nonspecific clinical symptoms, resulting in a limited role for preliminary tests. Aims: The present study aims to highlight the utility of endoscopic brush cytology (EBC) in the diagnosis of giardiasis in clinically unsuspected cases. Materials and Methods: Endoscopic brush smears (EBS) are routinely obtained in all patients presenting with gastric symptoms. The present study is a retrospective analysis of EBS, consis...

  17. Poly(HEMA) brushes emerging as a new platform for direct detection of food pathogen in milk samples

    Czech Academy of Sciences Publication Activity Database

    Rodriguez-Emmenegger, Cesar Adolfo; Avramenko, Oxana; Brynda, Eduard; Škvor, J.; Bologna Alles, A.

    2011-01-01

    Roč. 26, č. 11 (2011), s. 4545-4551. ISSN 0956-5663 R&D Projects: GA AV ČR KAN200670701; GA ČR GAP503/10/0664 Institutional research plan: CEZ:AV0Z40500505 Keywords : surface plasmon resonance * food-borne pathogens * polymer brushes Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 5.602, year: 2011

  18. Surface characterization of electron-beam irradiated polymer brushes

    International Nuclear Information System (INIS)

    Polymer brushes out of PS, P2VP, PNIPAMM and PAA were used to modify and control the surface potential of Si-wafers. The polymers brushes formed layers of thickness of less than 20 nm and significantly changed the surface potential of the substrate, which was investigated with contact angle measurements. Their chemical composition was studied by XPS. Electron irradiation was employed to modify the brushes by different radiation doses. With XPS and Zetapotential measurements we were able to specify the surface composition after electron beam treatment. Changes in surface composition and the structure of the grafted polymer brushes allowed to qualify cross-linkages and degradation processes. By varying the dose we could adjust on the one hand the decomposition of the polymer and on the other hand the amount of hydrophilic groups. We know that the adsorption of proteins on polymers highly depends on the surface potential. This work could be used to control the surface potential of the polymer brush as well as the adsorption of proteins, only by varying the radiation dose. The chosen substrate silicon is also attractive for lab-on-chip applications of those modified brushes. (orig.)

  19. Polyelectrolyte brushes at the air/water interface

    International Nuclear Information System (INIS)

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

  20. Insertion of nanoparticles into polymer brush under variable solvent conditions

    Science.gov (United States)

    Egorov, S. A.

    2012-10-01

    In this work, two-dimensional lattice-based self-consistent field theory is used to study the free energy cost associated with the insertion of a nanoparticle into a polymer brush. The nanoparticle is modeled as a cylinder and the self-consistent field equations are formulated on a cylindrical lattice. The use of two-dimensional formalism makes it possible to take into account the distortion of the brush density profile due to the embedded nanoinclusion. The insertion free energy penalty is analyzed as a function of the particle size, the brush grafting density, and the solvent quality. In agreement with the earlier simulation work, we find that the insertion free energy cost increases both with the particle size and the brush grafting density and decreases with deteriorating solvent quality. For nanoparticles located deep inside the brush, the insertion free energy is shown to scale with either squared (good solvent) or cubed (poor solvent) monomer volume fraction profile, in agreement with the earlier theoretical results. For shallow nanoinclusions located close to the brush surface, the insertion free energy is shown to scale linearly with the monomer volume fraction profile under both good and theta solvent conditions, again in agreement with the earlier work.

  1. Brush development for underwater ship hull coating maintenance

    Science.gov (United States)

    Tribou, Melissa Eileen

    Ship hull grooming has been proposed as an environmentally friendly method of maintaining ship hull coatings in a fouling-free condition. It is defined as the frequent and gentle cleaning of a ship hull coating to prevent the establishment of fouling. This research investigated the grooming tool properties and operational requirements needed to implement the method. The grooming tool needs to provide sufficient force to remove incipient fouling without damaging the surface and consume minimal energy. Research showed that a vertical rotating brush design containing brushes filled with angled polypropylene bristles provided an effective method. This brush system was able to successfully prevent incipient fouling from becoming established on a copper ablative and two silicone fouling release coatings when groomed on a weekly basis; however, biofilm was not completely controlled. Brush design and operational parameters in relation to brush normal forces were investigated and models were developed to understand the relationship between bristle stiffness, dimensions, and angular velocity. A preliminary look at wear found that bristle stiffness has an effect on the degree of marring of the surface of a silicone fouling release coating. The knowledge gained by this research may be used to optimize grooming brush design and operational parameters that can be applied to the design and deployment of low power autonomous underwater vehicles that will groom the ship while in port.

  2. Carbon-brush collector maintenance on turbine-generators

    Energy Technology Data Exchange (ETDEWEB)

    Maughan, C.V. [Maughan Engineering Consultants, Schenectady, NY (United States)

    2005-07-01

    Carbon-brush collectors are small components in turbine generators that perform the function of transferring current from excitation power sources to the rotating fields of synchronous generators. Collectors operate at 100 to 700 volts DC in a noisy and windy atmosphere and are one of the most frequent causes of generator forced outages. As such, their condition must be monitored regularly through visual inspection. While the inspection and maintenance effort is relatively minor, it is often overlooked or done improperly. The key to reliable collector performance consists of making daily direct observations, recognizing the warning signals of impending failure, and taking timely corrective maintenance action. Dependable brush-to-collector current transfer relies on the following 3 conditions, which must be satisfied simultaneously: collector surface film; brush contact pressure; and continuous brush-to-ring contact. Causes of collector outages include planned outages to resurface the collector, or forced outages due to collector flashover. This paper presented suggestions on how to identify an impending failure, along with guidelines for corrective maintenance to avoid a turbine/generator forced outage. Information was provided on retrofit or fixed brush holders with removable brush holders. A checklist for daily inspection and weekly maintenance was presented along with measures to perform at each shutdown. 1 tab., 12 figs.

  3. Cues to Action as Motivators for Children's Brushing.

    Science.gov (United States)

    Walker, Kimberly K; Steinfort, Erin L; Keyler, Maria J

    2015-01-01

    Dental caries is the most common chronic childhood disease. Home self-care procedures are the most important strategies to prevent tooth decay. Brushing is the most important single intervention for the prevention of tooth decay, yet compliance is not practiced and there is limited understanding of children's behavioral decisions. Guided by the Health Belief Model, this study consisted of eight focus groups with children in the second through fifth grades at three different socioeconomic-level school districts to determine the cues to action that are motivating or can motivate their brushing behavior. Results indicated children are primarily motivated to brush for aesthetic reasons, mainly due to viewed media pictures of "perfect" teeth. Other less commonly expressed motivations for brushing stemmed from interpersonal connections, such as relatives with dentures. Social media, on the other hand, played a key role in some children's understanding of more advanced oral health connections such as links between cardiovascular and oral disease, and smoking and oral cancer. These links were viewed as threatening to children to motivate better brushing. Additionally, the study found that home computers can be used as an external motivator to deliver tailored messages to encourage better brushing. PMID:25204365

  4. Poly(HEMA) brushes prepared by surface-initiated atom transfer radical polymerization for the detection of Cronobacter in milk and powdered infant formulas

    Czech Academy of Sciences Publication Activity Database

    Avramenko, Oxana; Rodriguez-Emmenegger, Cesar Adolfo; Brynda, Eduard

    Prague : Charles University, 2010. P6.8. [Conference of the European Colloid and Interface Society /24./. 05.09.2010-10.09.2010, Prague] Institutional research plan: CEZ:AV0Z40500505 Keywords : polymer brush * Cronobacter Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  5. Direct observation of polyelectrolyte brushes under wet and dry conditions by atmospheric scanning electron microscopy.

    Science.gov (United States)

    Higuchi, Takeshi; Konyuba, Yuji; Nishiyama, Hidetoshi; Suga, Mitsuo; Takahara, Atsushi; Jinnai, Hiroshi

    2016-04-01

    Polyelectrolyte brushes are polyelectrolyte polymers with one end fixed to a substrate. In this study, direct nano-scale visualization of polyelectrolyte brushes was carried out under 'aqueous conditions' by atmospheric scanning electron microscopy. The thickness of the polyelectrolyte brush layer was measured under both dry and aqueous conditions, experimentally confirming the swollen state of the brushes. These experimental findings qualitatively agreed with the results from previous neutron reflectivity experiments using similar polyelectrolyte brushes. Such direct visualization of polymer brushes in real space opens up a new route for better understanding their surface properties, such as friction, adhesion and wettability. PMID:26581481

  6. Effects of Geometry on Leakage Flow Characteristics of Brush Seal

    Institute of Scientific and Technical Information of China (English)

    Yuan Wei; Zhaobo Chen∗; Yinghou Jiao

    2015-01-01

    In order to better application of brush seal in rotating machinery, the leakage flow characteristics of the brush seal considering geometry effects are numerically analyzed using Reynolds⁃Averaged Navier⁃Stokes ( RANS) model coupling with a non⁃Darcian porous medium model. The reliability of the present numerical method is proved, which is in agreement with the experimental and numerical results from literatures. Three different bristle pack thicknesses, fence heights and initial clearances under different pressure ratios, rotational velocities and other operating conditions are utilized to investigate the effects of geometry modification on the brush seal leakage flow behaviors. It discusses the effectiveness of various geometry configurations outlining important flow features. The results indicate that the increase of fence height and clearance would lead to the increase of leakage rate. But the leakage is not linearly with respect to the bristle pack thickness, and the effect of rotational velocity is not obvious. Moreover, the detailed leakage flow fields and pressure distributions along the rotor surface, free bristle height, and fence height of the brush seals are also presented. The static pressure drop amplitude through the bristle pack and the pressure rise amplitude through the cavity would increase while the pressure differential increases. And the axial pressure is the main reason of bristle blow down. The results provide theoretical support for the brush seal structure optimal design.

  7. What information can frictional properties of polymer brushes tell us?

    Science.gov (United States)

    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).

  8. Specific ion modulated thermoresponse of poly(N-isopropylacrylamide) brushes.

    Science.gov (United States)

    Humphreys, Ben A; Willott, Joshua D; Murdoch, Timothy J; Webber, Grant B; Wanless, Erica J

    2016-02-17

    The influence of specific anions on the equilibrium thermoresponse of poly(N-isopropylacrylamide) (pNIPAM) brushes has been studied using in situ ellipsometry, quartz crystal microbalance with dissipation (QCM-D) and static contact angle measurements between 20 and 45 °C in the presence of up to 250 mM acetate and thiocyanate anions in water. The thickness and changes in dissipation exhibited a broad swelling transition spanning approximately 15 °C from collapsed (high temperatures) to swollen conformation (low temperatures) while the brush surface wettability changed over approximately 2 °C. In the presence of the kosmotropic acetate anions, the measured lower critical solution temperature (LCST) by the three techniques was very similar and decreased linearly as a function of ionic strength. Conversely, increasing the concentration of the chaotropic thiocyanate anions raised the LCST of the pNIPAM brushes with variation in the measured LCST between the three techniques increasing with ionic strength. The thickness of the pNIPAM brush was seen to progressively increase with increasing thiocyanate concentration at all temperatures. It is proposed that specific ion binding of the chaotropic thiocyanate anion with pNIPAM amide moieties increases the electrostatic intra- and intermolecular repulsion within and between pNIPAM chains. This allows the brush to begin to swell at higher temperatures and to an overall greater extent. PMID:26840183

  9. Excluded volume effects in compressed polymer brushes: A density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Cangyi; Tang, Ping, E-mail: pingtang@fudan.edu.cn, E-mail: fengqiu@fudan.edu.cn; Qiu, Feng, E-mail: pingtang@fudan.edu.cn, E-mail: fengqiu@fudan.edu.cn [The State Key Laboratory of Molecular Engineering of Polymers, Key Laboratory of Computational Physical Sciences, Department of Macromolecular Science, Fudan University, Shanghai 200433 (China); Shi, An-Chang [Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1 (Canada)

    2015-03-28

    A classical density functional theory (DFT) is applied to investigate the behavior of compressed polymer brushes composed of hard-sphere chains. The excluded volume interactions among the chain segments are explicitly treated. Two compression systems are used to study the behavior of brush-wall and brush-brush interactions. For the brush-brush systems, an obvious interpenetration zone has been observed. The extent of the interpenetration depends strongly on the grafting density. Furthermore, the repulsive force between the brush and wall or between the two brushes has been obtained as a function of the compression distance. Compared to the prediction of the analytic self-consistent field theory, such force increases more rapidly in the brush-wall compression with high polymer grafting densities or at higher compressions. In the brush-brush compression system, the interpenetration between the two compressed brushes creates a “softer” interaction. The influence of hard-sphere solvents on the behavior of compressed brushes is also discussed.

  10. Macromolecular Brushes as Stabilizers of Hydrophobic Solute Nanoparticles.

    Science.gov (United States)

    Luo, Hanying; Raciti, David; Wang, Chao; Herrera-Alonso, Margarita

    2016-06-01

    Macromolecular brushes bearing poly(ethylene glycol) and poly(d,l-lactide) side chains were used to stabilize hydrophobic solute nanoparticles formed by a rapid change in solvent quality. Unlike linear diblock copolymers with the same hydrophilic and hydrophobic block chemistries, the brush copolymer enabled the formation of ellipsoidal β-carotene nanoparticles, which in cosolvent mixtures developed into rod-like structures, resulting from a combination of Ostwald ripening and particle aggregation. The stabilizing ability of the copolymer was highly dependent on the mobility of the hydrophobic component, influenced by its molecular weight. As shown here, asymmetric amphiphilic macromolecular brushes of this type may be used as hydrophobic drug stabilizers and potentially assist the shape control of nonspherical aggregate morphologies. PMID:27035279

  11. Numerical simulations of plasma brush behavior in hybrid armatures

    Science.gov (United States)

    Hawke, R. S.; Pincosy, P. A.

    1993-01-01

    Hybrid armatures used to accelerate projectiles in railguns are often the consequence of using a solid armature or in some cases the preferred armature type. Although hybrid armatures are often used, their design has been empirical and their performance sporadic. As a first step towards understanding hybrid design and performance, we have begun a combined numerical simulation and experimental verification effort. This paper will describe numerical simulations performed with a quasi 1-D MHD code (CONFUSE) which has been applied to simulate the behavior of plasma brushes used in hybrid armatures. The simulations have provided estimates of the plasma brush length, resistive voltage drop and temperatures corresponding to a range of; 1) brush gap size, 2) fuse thickness, and 3) magnetic pressure. The results of these simulations is presented and discussed.

  12. Numerical simulations of plasma brush behavior in hybrid armatures

    Energy Technology Data Exchange (ETDEWEB)

    Hawke, R.S.; Pincosy, P.A.

    1992-04-01

    Hybrid armatures used to accelerate projectiles in railguns are often the consequence of using a solid armature or in some cases the preferred armature type. Although hybrid armatures are often used, their design has been empirical and their performance sporadic. As a first step towards understanding hybrid design and performance, we have begun a combined numerical simulation and experimental verification effort This paper will describe numerical simulations performed with liquid 1-D MHD code (CONFUSE) which has been applied to simulate the behavior of plasma brushes used in hybrid armatures. The simulations have provided estimates of the plasma brush length, resistive voltage drop and temperatures corresponding to a range of; (1) brush gap size, (2) fuse thickness, and (3) magnetic pressure. The results of these simulations will be presented and discussed.

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

    DEFF Research Database (Denmark)

    Danielsen, E M; van Deurs, B

    1997-01-01

    lacking a N-terminal signal peptide for membrane translocation, was discovered in these complexes as well, and in gradient centrifugation brush border enzymes and galectin-4 formed distinct soluble high molecular weight clusters. Immunoperoxidase cytochemistry and immunogold electron microscopy showed......Detergent-insoluble complexes prepared from pig small intestine are highly enriched in several transmembrane brush border enzymes including aminopeptidase N and sucrase-isomaltase, indicating that they reside in a glycolipid-rich environment in vivo. In the present work galectin-4, an animal lectin...... that galectin-4 is indeed an intestinal brush border protein; we also localized galectin-4 throughout the cell, mainly associated with membraneous structures, including small vesicles, and to the rootlets of microvillar actin filaments. This was confirmed by subcellular fractionation, showing about...

  14. Surface and interface structure of diblock copolymer brushes

    Science.gov (United States)

    Akgun, Bulent

    The main objective of the work presented in this thesis is to understand the surface and interface structure and dynamics of diblock copolymer brushes (DCBs). DCBs are stimuli-responsive materials and the surface properties of a DCB can be changed from those characteristic of one polymer block to those characteristic of the other one by treating the DCB with a solvent selective for one of its blocks. For this purpose, polystyrene- block-polyacrylate or polyacrylate-block-polystyrene brushes were synthesized using the "grafting from" technique in combination with atom transfer radical polymerization (ATRP). In the first part of this project the internal structure of DCBs after the synthesis and surface rearrangement were investigated using neutron reflectivity (NR) and grazing incidence small angle X-ray scattering (GISAXS). It was found that the internal brush structure depends strongly on the synthesis sequence of polymer blocks and the value of chiN. For small values of chiN (chiN ≤ 11), a model of two layers with an interfacial region of finite width provides a good description of the data. The interface width is found to be larger for DCBs which have the polymer block with the lower surface energy synthesized next to the substrate. A three layer model must be used to describe the structure of DCBs of larger chiN values (chiN ≤ 23) and of sufficiently asymmetric composition. The necessity of including a third layer is consistent with the presence of a lateral ordering of some type in the center of the brush, as evidenced by correlation peaks in the GISAXS data. The spacing of the in-plane ordering varies with the thickness of the poly(methyl acrylate) (PMA) block. After a DCB is treated with a selective solvent, Bragg rods appear in the GISAXS pattern. The appearance of Bragg rods indicates the formation of a new 2D structure which has a lateral spacing on the order of the total thickness of the brush. The Bragg rods disappear upon heating to 80

  15. Colloidal lithography for fabricating patterned polymer-brush microstructures

    Directory of Open Access Journals (Sweden)

    Tao Chen

    2012-05-01

    Full Text Available We exploit a series of robust, but simple and convenient colloidal lithography (CL approaches, using a microsphere array as a mask or as a guiding template, and combine this with surface-initiated atom-transfer radical polymerization (SI-ATRP to fabricate patterned polymer-brush microstructures. The advantages of the CL technique over other lithographic approaches for the fabrication of patterned polymer brushes are (i that it can be carried out with commercially available colloidal particles at a relatively low cost, (ii that no complex equipment is required to create the patterned templates with micro- and nanoscale features, and (iii that polymer brush features are controlled simply by changing the size or chemical functionality of the microspheres or the substrate.

  16. Synthesis and characterization of polypyrrole doped with anionic spherical polyelectrolyte brushes

    Directory of Open Access Journals (Sweden)

    N. Su

    2012-09-01

    Full Text Available The procedures for the synthesis of polypyrrole (PPy doped with anionic spherical polyelectrolyte brushes (ASPB (PPy/ASPB nanocomposite by means of in situ chemical oxidative polymerization were presented. Fourier transform infrared spectroscopy (FTIR and Raman spectroscopic analysis suggested the bonding structure of PPy/ASPB nanocomposite. Scanning electron microscopy (SEM was used to confirm the morphologies of samples. The crystallographic structure, chemical nature and thermal stability of conducting polymers were analyzed by X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS and Thermo-gravimetric analysis (TGA respectively. Investigation of the electrical conductivity at room temperature showed that the electrical conductivity of PPy/ASPB nanocomposite was 20 S/cm, which was higher than that of PPy (3.6 S/cm.

  17. An Overview of Non-Metallic Brush Seal Technology

    Science.gov (United States)

    Ruggiero, Eric J.

    2009-01-01

    Non-metallic brush seals are ultra-low flow sealing elements ideal for low pressure differentials (seal is advantageous in terms of sealing capability during transients. However, if not designed properly, the bristle pack compliance can be detrimental to the performance of the seal. GE GLobal Research has investigated the stiffness and heat generation properties of non-metallic brush seals made from Kevlar and Carbon Fiber. The presentation will review the progress made on the design points of the seals, as well as highlight some current commercial applications of the technology.

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

    Directory of Open Access Journals (Sweden)

    Stephanie Christau

    2014-06-01

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

  19. Immunoelectrophoretic studies on pig intestinal brush border proteins

    DEFF Research Database (Denmark)

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

    1977-01-01

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

  20. Suppressing Pseudomonas aeruginosa adhesion via non-fouling polymer brushes

    Czech Academy of Sciences Publication Activity Database

    Rodriguez-Emmenegger, Cesar; Decker, A.; Surman, František; Preuss, C. M.; Sedláková, Zdeňka; Zydziak, N.; Barner-Kowollik, C.; Schwartz, T.; Barner, L.

    2014-01-01

    Roč. 4, č. 110 (2014), s. 64781-64790. ISSN 2046-2069 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0109; GA ČR GAP106/12/1451 Institutional support: RVO:61389013 Keywords : polymer brushes * tissue engineering * biology Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.840, year: 2014

  1. Keep Kids' Mouths Healthy: Brush 2min2X

    Science.gov (United States)

    ... More about BRUSHING Visit a Dentist Visit a Dentist Take your kids to see a dentist no ... and freshen breath. Visit a dentist Visit a Dentist Kids and parents – it’s important to visit ...

  2. Spatially resolved functionalization of hierarchically structured antifouling polymer brushes

    Czech Academy of Sciences Publication Activity Database

    de los Santos Pereira, Andres; Kostina, Nina Yu.; Bruns, M.; Rodriguez-Emmenegger, Cesar; Barner-Kowollik, C.

    Prague : Institute of Macromolecular Chemistry AS CR, 2015. s. 77. ISBN 978-80-85009-82-8. [Functional Polymers at Bio -Material Interfaces - 79th Prague Meeting on Macromolecules. 28.06.2015-02.07.2015, Prague] Institutional support: RVO:61389013 Keywords : polymer brushes * surface characterization Subject RIV: CD - Macromolecular Chemistry

  3. Multifocal Rhizopus microsporus lung infection following brush clearing

    Directory of Open Access Journals (Sweden)

    Artsiom V. Tsyrkunou

    2014-10-01

    Full Text Available We report a case of pulmonary Rhizopus microsporus infection in a patient with untreated diabetes following brush clearing. The patient was successfully treated with a combined medical and surgical approach with complete resolution of the lung lesions and remains asymptomatic at 11-month follow-up.

  4. Conformational switching of modified guest chains in polymer brushes

    Science.gov (United States)

    Romeis, D.; Sommer, J.-U.

    2013-07-01

    Using a numerical quasi off-lattice self-consistent field method which describes heterogeneous chains of spherical monomers we study the case of a densely grafted polymer brush with a fraction of free chain ends being replaced by a modified end-group differing in size and solvent selectivity. We can confirm the observation from molecular dynamics simulations that upon changing the solvent conditions, a switching in location of end-groups which are bigger than monomers from a state "exposed" to the solvent (on the top of the brush) to a "hidden" state (inside the brush) takes place. Our numerical method allows a detailed study of the switching effect as a function of the relevant parameters, such as grafting density, chain length, size of end-groups and their volume fraction. We find that the switching effect is enhanced for long chains, low fractions of modified chains, and big end-groups. We consider the case of low fraction of modified chains in more detail using a test chain method. Here, we explore the optimal grafting density as a function of the size of the end-groups, where the switching is most sensitive. These values can be in the experimental range for end-groups which are at least 3-4 times bigger than the monomers. The end-groups can be realized by attaching nano-particles to the last monomer of a brush-chain.

  5. Self-organization of multivalent counterions in polyelectrolyte brushes

    Science.gov (United States)

    Wu, Jianzhong

    2013-03-01

    The structure and interfacial properties of a polyelectrolyte brush (PEB) depend on a broad range of parameters such as the polymer charge and grafting density, counterion valence, salt concentration, and solvent conditions. These properties are of fundamental importance in technological applications of PEBs including colloid stabilization, surface modification and lubrication, and in functioning of biological systems such as genome packaging in single-strand DNA/RNA viruses. Despite intensive studies by experiments, molecular simulations, and myriad analytical methods including scaling analyses, self-consistent-field theory, and most recently density functional theory, the behavior of PEBs in the presence of multivalent counterions remains poorly understood. In this talk, I will present a density functional method for polyelectrolyte brushes and discuss self-organization of multivalent counterions within highly charged polyelectrolyte brushes. The counterion-mediated attraction between polyions leads to a first-order phase transition similar to that for a neutral brush in a poor solvent. The self-organization of multivalent counterions results in a wavelike electrostatic potential and charge density that oscillate between positive and negative values.

  6. Electric toothbrushes--for whom are they designed?

    Science.gov (United States)

    Ciancio, Sebastian

    2002-05-01

    Powered toothbrushes were first introduced on a large scale in the early 1960s. However, because of a clear lack of superiority compared with manual brushes, and problems with mechanical breakdowns, their sales decreased significantly. However, recommendation for their use continued in special populations with dexterity and cognition problems. The 1990s ushered in an era of new technology, and studies began to suggest superiority of some powered brushes, particularly those using oscillating-rotating or counter-rotational actions. Some studies have shown interproximal cleansing abilities superior to those of manual brushes and yielding results similar to those achieved with the use of a manual brush and floss. Both controlled and open-labeled studies have suggested that electric brushes improve gingival health with patients who routinely used manual brushes prior to using these new powered brushes, and safety has been clearly established. In recommending powered toothbrushes, practitioners should familiarize themselves with the products available, with the clinical studies supporting their benefits compared with manual brushes, their safety and ease of use, and the patient's economic status. PMID:12161387

  7. Controlled Synthesis of Polymer Brushes via Polymer Single Crystal Templates

    Science.gov (United States)

    Zhou, Tian

    A novel synthetic method of polymer brushes using polymer single crystals (PSCs) as solid-state templates is introduced in this study. PSC has a quasi-2D lamellae structure with polymer chains fold back-and-forth perpendicular to the lamellae surfaces. During crystallization, the chain ends are excluded from the unit cell onto the lamellae surfaces, which makes the material extremely versatile in its functionality. Such structure holds the unique capability to harvest nanoparticles, or being immobilized onto macroscopic flat surfaces. After dissolving PSCs in good solvent, polymer brushes are chemically tethered on either nanoparticles or flat macroscopic surfaces. Because the chain-folding structure can be conveniently tailored by changing the molecular weight of polymer and the crystallization temperature, the thickness, grafting density and morphology of resulted polymer brushes can be precisely controlled. As a model system, poly(?-caprolactone) with thiol or alkoxysilane terminal groups was used, and polymer brushes were successfully prepared on both nanoparticles and glass/Au flat surfaces. The structure-property relationships of the as-prepared polymer brushes were studied in detail using multiple characterization techniques. First of all, when functionalizing nanoparticles, by engineering the chain-folding structure of the PSCs, interesting complex nanostructures can be formed by nanoparticles including Janus nanoparticles and nanoparticle dimers. These unique structures render hybrid nanoparticles very interesting responsive behavior which have been studied in detail in this dissertation. When grafted onto a flat surface on the other hand, not only the molecular weight and grafting density can be precisely controlled, the tethering points of a single polymer chain can also be conveniently tailored, resulting polymer brushes with either tail or loop structures. Such difference in brush structure can significantly alter the properties of functional surface

  8. [Gingival abrasion and plaque removal with manual vs. electric toothbrushes].

    Science.gov (United States)

    Niemi, M L; Ainamo, J; Etemadzadeh, H

    1988-03-01

    In a clinical study, the relative incidence of gingival injuries after standardized tooth brushing was tested by 22 volunteer dental assistants whose teeth were brushed with a soft multi-tufted toothbrush, a manual V-form toothbrush, and an electric toothbrush. At the beginning of the study, a dental hygienist cleaned the right or left side of the jaw of each subject with a manual V-form toothbrush or an electric toothbrush; the other side was manually cleaned with a multi-tufted toothbrush. At the second cleansing one week later, the same dental hygienist cleaned the side contralateral to that brushed in the first test week with the multi-tufted brush; the manual V-form brush was used instead of the electric toothbrush and vice versa. The number of new gingival lesions was recorded after each brushing. The cleansing effect was established by determining the amount of residual plaque. The subjects did not know which type of toothbrush was used to cleanse the evaluated side of the jaw. The results showed that the manual V-form toothbrush abraded the gingiva more than the electric toothbrush (p less than 0.005). A similar difference was found between the manual multi-tufted and the electric toothbrush (p less than 0.05). No significant differences could be established with respect to the plaque-removing properties of the three types of toothbrush tested. PMID:3273776

  9. Brush-eating device promises reforestation, wood energy aid

    Energy Technology Data Exchange (ETDEWEB)

    Blackman, T.

    1981-01-01

    An invention which began as a low-ground-pressure skidder developed into a machine which clears brush, thins plantations, and can harvest wood for energy. First came the notion of an extra-low-ground-pressure log skidder. A swinging chopper was added to the front to clear the skid roads. Working in manzanita brush 10 to 12 foot tall, and with stems up to 18 inches in diameter, the Shar 20 can clear one to two and a half acres an hour. The 30 will be able to clear two to five acres an hour. The big machine will have two chopper heads rotating in opposite directions to force the chopped wood into a chipper built into the machine. Chips will be blown to a van following the harvester so they can be used for hog fuel or as feedstock for methanol production. The head spins at a relatively slow 450 rpm - a safety factor. Surrounding brush catches most of the cut material, but an occasional chunk of wood does fly several yards. Companies are paying more attention to reforestation. Clearing the land will leave a mulch-like debris on the ground. This offers some shade and helps retain soil moisture. Even when brush is harvested for energy, about 10% of the material is left on the ground. California's Department of Forestry wants to start a five-year clearing cycle for the chaparral stands, ''mowing'' a million acres a year and returning every fifth year to reclear the brush. California alone has 27 million acres of brushland not suitable for timber. A brushy acre averages from 30 to 200 tons of wood at 10% moisture content. The machines are designed to run at up to 12 mph when moving.

  10. Hydrologic Effects of Brush Management in Central Texas

    Science.gov (United States)

    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.

  11. Electric vehicle motors and controllers

    Science.gov (United States)

    Secunde, R. R.

    1981-01-01

    Improved and advanced components being developed include electronically commutated permanent magnet motors of both drum and disk configuration, an unconventional brush commutated motor, and ac induction motors and various controllers. Test results on developmental motors, controllers, and combinations thereof indicate that efficiencies of 90% and higher for individual components, and 80% to 90% for motor/controller combinations can be obtained at rated power. The simplicity of the developmental motors and the potential for ultimately low cost electronics indicate that one or more of these approaches to electric vehicle propulsion may eventually displace presently used controllers and brush commutated dc motors.

  12. Droplet:A Virtual Brush Model to Simulate Chinese Calligraphy and Painting

    Institute of Scientific and Technical Information of China (English)

    XiaoFeng Mi; Min Tang; Jin-Xiang Dong

    2004-01-01

    This paper proposes a virtual brush model based on droplet operation to simulate Chinese calligraphy and traditional Chinese painting in real time. Two ways of applying droplet model to virtual calligraphy and painting are discussed in detail. The second droplet model is more elaborated and can produce more vivid results while being slightly more time-consuming. The novel feature of the proposed droplet virtual brush model successfully enables the simulation painting system to overcome the poor expressional ability of virtual brush based on particle system and avoids the complex evaluation of physical brush with solid model. The model,derived from the actual calligraphy and painting experience, due to the simplicity of the droplet operation and its powerful expressive ability, considerably improves the performance of the simulation system and maintains painting effect comparable with real brush by supporting special Chinese brush effect such as dry brush, feng and stroke diffusion.

  13. Impact of self-tongue brushing on taste perception in Thai older adults: A pilot study.

    Science.gov (United States)

    Madiloggovit, Jirakate; Chotechuang, Nattida; Trachootham, Dunyaporn

    2016-01-01

    Oral hygiene influences taste, affecting appetite and nutrition in older adults. However, the impact of self-administered tongue brushing on their taste perceptions was unclear. This pilot study (N = 44) was aimed to observe the changes in taste thresholds using Filter Paper Disc after tongue brushing in Thai older adults. Based on the results, continuous tongue brushing for 3 months reduced tongue coat (p taste in 74% of participants. Sweet and salty recognition thresholds were reduced in both anterior and posterior tongue, while sour and bitter thresholds were reduced only in posterior tongue. No changes in umami (savory) were observed. Daily brushing was more effective than weekly brushing in improving the sweet and bitter tastes. The data suggested that tongue brushing could improve perception of multiple tastes and daily tongue brushing was recommended as routine personal care for older adults. This study supports further investigation in a randomized-controlled setting. PMID:26747405

  14. A PET activation study of brush-evoked allodynia in patients with nerve injury pain

    DEFF Research Database (Denmark)

    Witting, Nanna; Kupers, Ron; Svensson, Peter; Jensen, Troels Staehelin

    2006-01-01

    . A direct post hoc comparison of brush -and allodynia-induced rCBF changes showed that allodynia was associated with significantly stronger activations in orbitofrontal cortex and ipsilateral insula whereas non-painful brushing more strongly activated SI and BA 5/7. These findings indicate that...... allodynia. Nine patients with peripheral nerve injury were scanned during rest, brush-evoked allodynia, and brushing of normal contralateral skin. PET data were analyzed for the whole group and for single subjects. Allodynic stimulation activated the contralateral orbitofrontal cortex (BA 11) in every...... patient. Whereas normal brushing activated most strongly the contralateral insular cortex, allodynic brushing produced an ipsilateral activation in this area. Another important difference between normal and allodynic brushing was the absence of a contralateral primary somatosensory cortex (SI) activation...

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

    KAUST Repository

    Lanas, Vanessa

    2013-11-01

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

  16. Assessment of Pain Response in Capsaicin-Induced Dynamic Mechanical Allodynia Using a Novel and Fully Automated Brushing Device

    OpenAIRE

    du Jardin, Kristian G; Gregersen, Lise S; Røsland, Turid; Uggerhøj, Kathrine H; Petersen, Lars J.; Arendt-Nielsen, Lars; Gazerani, Parisa

    2013-01-01

    BACKGROUND: Dynamic mechanical allodynia is traditionally induced by manual brushing of the skin. Brushing force and speed have been shown to influence the intensity of brush-evoked pain. There are still limited data available with respect to the optimal stroke number, length, force, angle and speed. Therefore, an automated brushing device (ABD) was developed, for which brushing angle and speed could be controlled to enable quantitative assessment of dynamic mechanical allodynia.OBJECTIVES: T...

  17. Research On Permanent Magnet BLDC for small electric vehicle

    OpenAIRE

    Gupta, Uma

    2014-01-01

    In this paper, different electric motors are studied and compared to see the benefits of each motor and the one that is more suitable to be used in the electric vehicle applications. There are five main electric motor types, DC, induction, permanent magnet synchronous, switched reluctance and brush-less DC motors are studied.

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

    Science.gov (United States)

    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.

  19. pH-Responsive Behavior of Poly(acrylic acid) Brushes of Varying Thickness

    Science.gov (United States)

    Yadav, Vivek; Robertson, Megan; Conrad, Jacinta

    2015-03-01

    We have investigated the pH-dependent response of polyelectrolyte brushes of varying thickness. Our model system consists of poly(acrylic acid) brushes, which change from hydrophobic and neutral at low pH to hydrophilic and negatively charged at high pH, synthesized using a grafting-from approach at constant grafting density. As the polymer brush thickness increased, the brushes exhibited greater hysteresis in static water contact angle as a function of pH. We extracted the pKa of the polymer brushes from contact angle measurements. The relationship between the pKa and brush thickness depended on the order in which the brushes were exposed to solutions of varying pH: pKa decreased on increasing brush thickness when going from basic to acidic medium whereas pKa increased on increasing brush thickness when going from acidic to basic medium. We speculate that the origin of hysteresis can be explained by pH-dependent conformational changes in these polyelectrolyte brushes.

  20. Wettability and antifouling behavior on the surfaces of superhydrophilic polymer brushes.

    Science.gov (United States)

    Kobayashi, Motoyasu; Terayama, Yuki; Yamaguchi, Hiroki; Terada, Masami; Murakami, Daiki; Ishihara, Kazuhiko; Takahara, Atsushi

    2012-05-01

    The surface wettabilities of polymer brushes with hydrophobic and hydrophilic functional groups were discussed on the basis of conventional static and dynamic contact angle measurements of water and hexadecane in air and captive bubble measurements in water. Various types of high-density polymer brushes with nonionic and ionic functional groups were prepared on a silicon wafer by surface-initiated atom-transfer radical polymerization. The surface free energies of the brushes were estimated by Owens-Wendt equation using the contact angles of various probe liquids with different polarities. The decrease in the water contact angle corresponded to the polarity of fluoroalkyl, hydroxy, ethylene oxide, amino, carboxylic acid, ammonium salt, sulfonate, carboxybetaine, sulfobetaine, and phosphobetaine functional groups. The poly(2-perfluorooctylethyl acrylate) brush had a low surface free energy of approximately 8.7 mN/m, but the polyelectrolyte brushes revealed much higher surface free energies of 70-74 mN/m, close to the value for water. Polyelectrolyte brushes repelled both air bubbles and hexadecane in water. Even when the silicone oil was spread on the polyelectrolyte brush surfaces in air, once they were immersed in water, the oil quickly rolled up and detached from the brush surface. The oil detachment behavior observed on the superhydrophilic polyelectrolyte brush in water was explained by the low adhesion force between the brush and the oil, which could contribute to its excellent antifouling and self-cleaning properties. PMID:22500465

  1. CORRELATION OF FINE NEEDLE ASPIRATION CYTOLOGY WITH BRONCHOALVEOLAR LAVAGE AND BRUSH SMEAR CYTOLOGY IN PULMONARY LESIONS

    Directory of Open Access Journals (Sweden)

    Surabhi

    2014-06-01

    Full Text Available BACKGROUND: Fine Needle Aspiration Cytology (FNAC, Bronchoalveolar Lavage (BAL and Brush Cytology are important diagnostic tools for evaluation of pulmonary lesions. Considering the limitations of these procedures correlation of these cytological techniques may help in improving accuracy and increasing the diagnostic yield. AIM: To determine the role of FNAC, Brush and BAL Cytology in pulmonary lesions and to correlate the efficacy of FNAC with Brush and BAL Cytology. MATERIALS AND METHODS: This prospective study was conducted on 78 patients with radiologically demonstrable pulmonary lesions in the department of pathology and Dr ML Chest Hospital, GSVM Medical College, Kanpur over a period from nov2011-july2013. The cases selected had to give consent for the procedure. Bronchoalveolar lavage, bronchial brush sample were taken and FNAC was done in the cases. RESULTS: In present study 78 cases of pulmonary lesions were subjected to FNAC and/ or Bronchoalveolar lavage and brush cytology. Among them 49 cases were selected in which all three procedures were done. The sensitivity and specificity for detecting lung tumors by FNAC was 96.29% and 95.45% which was more than that of BAL cytology (84.61%, 91.30% and Brush cytology (81.48%, 95.45%. FNA correlates with Brush and BAL cytology in 78.57% of malignant lesions. Among malignant lesions 84.61% of BAL and Brush cytology correlates with FNA for diagnosis of squamous cell carcinoma. FNA correlates with 66.67% of brush and 83.37% of BAL fluid cytology for diagnosis of adenocarcinoma. BAL and Brush both correlates with FNA in 83.33% cases of small cell carcinoma. Overall 85.71% of BAL and 82.14% of brush smear cytology correlates with FNA cytology for diagnosis of lung cancers. CONCLUSIONS: FNA, BAL and Brush cytology provide a high yield for evaluation of pulmonary lesions. BAL fluid and brush cytology correlated well with FNAC for diagnosis of lung cancers.

  2. Usage of polymer brushes as substrates of bone cells

    Institute of Scientific and Technical Information of China (English)

    Sabine A.LETSCHE; Annina M.STEINBACH; Manuela PLUNTKE; Othmar MARTI; Anita IGNATIUS; Dirk VOLKMER

    2009-01-01

    Implant methcal research and hssue eagmeer-ing both target the design of novel biomaterials for the improvement of human health and clinical applications. In order to develop improved surface coatings for hard tissue (bone)replacement materials and implant devices,we are developing micropartemed coatings consisting of polymer brushes. These are used as organic templates for the mineralization of calcium phosphate in oraer to improve adhesion of bone cells. First we give a shortaccount of the current state-of-the-art in this particular field of blomaterial development,while in the second part the preliminary results of cell culture experiments are presented,in which the biocompatibility of polymer brushes are tested on human mesenchvmal stem cells.

  3. Design of new responsive materials based on functional polymer brushes

    OpenAIRE

    Bittrich, Eva

    2010-01-01

    For the development of smart surfaces high attention is focused on stimuli-responsive polymers. Since type and rate of response to environmental stimuli can be regulated by chain length, composition, architecture and topology, polymer films offer a variety of opportunities to develop such stimuli-responsive surfaces. Here polymer brush surfaces designed for a controlled adsorption of proteins and a switchable activity of immobilized enzymes are presented. The work is focused on temperature as...

  4. Antifouling functionalizable surfaces based on block copolymer brushes for biosensors

    Czech Academy of Sciences Publication Activity Database

    de los Santos Pereira, Andres; Rodriguez-Emmenegger, Cesar; Bologna Alles, A.; Brynda, Eduard

    Strasbourg: European Materials Research Society, 2013. RP.1-1. [E- MRS 2013 Spring Meeting. 27.05.2013-31.05.2013, Strasbourg] R&D Projects: GA ČR GAP205/12/1702; GA ČR GAP106/12/1451; GA ČR GBP205/12/G118 Institutional support: RVO:61389013 Keywords : non-fouling * blood plasma * polymer brushes Subject RIV: BO - Biophysics

  5. Evaluation of brush seals for oil sealing applications

    OpenAIRE

    Akşit, Mahmut Faruk; Aksit, Mahmut Faruk

    2012-01-01

    After proven performance in gas turbine secondary flow and hot gas path sealing applications, brush seals are being considered for oil and oil mist applications in aero-engines and industrial turbines. In oil sealing applications shear heating and oil coking are major concerns. The field experience indicates that shear heating and oil coking issues can be managed if seal is designed properly. When seal stiffness is well controlled, combined with proper fiber material selection and leakage coo...

  6. A study of brush seal porous media resistance coefficients

    OpenAIRE

    Görgün, Erdem; Gorgun, Erdem

    2014-01-01

    Developments in turbine technologies lead to higher operating temperature and pressure conditions. Parasitic leakage flows around the turbine account for considerable efficiency losses that increase fuel cost dramatically. Brush seal has recently emerged as an improved sealing technology to provide better leakage performance and to replace classical labyrinth seals. In order to optimize efficiency, comprehensive study of the factors causing the leakage is required. The leakage performance of ...

  7. Brush Wellman公司的先进Cu/W技术

    Institute of Scientific and Technical Information of China (English)

    JuanSeputveda; 李学芳; 龙建国

    1999-01-01

    Brush Weltman陶瓷产品分公司已经用粉末冶金技术开发出了一种生产Cu/W复合材料的新型、低成本方法。这些材料有一系列的用途,包括用作微电子工业的基片和散热片,Juan Sepulveda和Lisa Valenzuela介绍了这种技术。

  8. Role of gastric brush cytology in the diagnosis of giardiasis

    Directory of Open Access Journals (Sweden)

    Varma Deepali

    2008-01-01

    Full Text Available Background: Giardiasis, common in developing countries, has mostly nonspecific clinical symptoms, resulting in a limited role for preliminary tests. Aims: The present study aims to highlight the utility of endoscopic brush cytology (EBC in the diagnosis of giardiasis in clinically unsuspected cases. Materials and Methods: Endoscopic brush smears (EBS are routinely obtained in all patients presenting with gastric symptoms. The present study is a retrospective analysis of EBS, consisting of 12 cases whose smears had revealed trophozoites of Giardia lamblia . Biopsy correlation was available in five cases. Results: The patients ranged in age from 15 to 78 years (mean age: 34.08 years with a 1:1 sex ratio. Stool examination in all 12 cases yielded negative results for giardiasis. Upper gastrointestinal endoscopy was normal in all these cases. EBS from these cases revealed Giardia trophozoites, which were identified by their typical morphology. Conclusions: Endoscopic brush cytology can be used as a reliable screening tool in the diagnosis of gastro-duodenal giardiasis in clinically unsuspected cases, especially in developing countries where parasitic infections are common.

  9. A Nanosecond Pulsed Plasma Brush for Surface Decontamination

    Science.gov (United States)

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

    2015-11-01

    This work optimizes a non-thermal, atmospheric pressure plasma brush for surface decontamination. The generated plasma plumes with a maximum length of 2 cm are arranged in a 5 cm long, brush-like array. The plasma was generated in ambient air with power are in the range of 1-3 mJ and 0.5-1.5 W, respectively. Helium containing varying concentrations of water vapor was evaluated as the carrier gas and was fed into the plasma chamber at a rate varying between 1 to 7 SLPM. Optimization of the cold plasma brush for surface decontamination was tested in a study of the plasma inactivation of two common pathogens, Staphylococcus aureus and Acinetobacter baumannii. Laminate surfaces inoculated with over-night cultured bacteria were subject to the plasma treatment for varying water concentrations in He, flow rates and discharge voltages. It was found that increasing the water content of the feed gas greatly enhanced the bactericidal effect. Emission spectroscopy was performed to identify the reactive plasma species that contribute to this variation. Additional affiliation: Frank Reidy Research Center for Bioelectrics

  10. Electrokinetic Transport in Nanochannels Grafted with Polyelectrolyte Brushes with End-Charging

    Science.gov (United States)

    Das, Siddhartha; Chen, Guang

    2015-11-01

    Electrokinetic transport in nanochannels grafted with polyelectrolyte (PE) brushes is important for applications such as ion transport, ion manipulation, flow valving, etc. We discuss here a semi-analytical mean field theory approach to study electrokinetic transport in nanochannels grafted with polyelectrolyte brushes with end-charging. The model first probes the thermodynamics and the electrostatics of the PE brushes by appropriately accounting for the entropic (elastic), excluded volume, and electrostatic effects. The resulting knowledge on the electrostatic potential and the PE configuration is next used to obtain the electroosmotic transport. Results demonstrate the role of surface charges (at the end of the PE brushes) in modifying (shrinking or swelling) the brush height. This, in turn, alters the electroosmotic body force and the PE brush layer induced drag force on the fluid flow; therefore, the flow field eventually evolves from a non-trivial interplay of the PE electrostatic, entropic, and excluded volume effects.

  11. Modeling helical polymer brushes using self-consistent field theory (SCFT)

    Science.gov (United States)

    Mahalik, Jyoti; Sumpter, Bobby; Kumar, Rajeev

    We investigate structure of helical polymer brushes in terms of segment density distribution and local helical ordering using SCFT. A flexible chain model with vector potential was used to model liquid crystalline-like ordering in the brushes. The effects of surface grafting density, polymer molecular weight and the solvent quality on the brush structure were investigated. For densely grafted polymer brushes or the brushes made up of high molecular weight polymers, immersed in good quality solvent, stronger orientational ordering was found near the edge of the brushes (i.e., far from the grafting surface). Furthermore, an increase in the orientational ordering near the grafted end was found with decrease in solvent quality or decrease in molecular weight and decrease in surface grafting density. Computer Science and Mathematics Division, Oak Ridge National Laboratory.

  12. Discriminatory bio-adhesion over nano-patterned polymer brushes

    Science.gov (United States)

    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

  13. Is osmotic pressure relevant in the confinement of a polymer brush

    International Nuclear Information System (INIS)

    Polymer brushes are highly dense arrays of polymers grafted to an interface and are powerful ways to control the forces of adhesion, lubrication and friction. A key property of the brush that governs its behavior is how the structure of the brush responds to external forces and to confinement. We have developed a unique new setup that combines a surface force type apparatus with neutron reflection. Using this device, we measured the structure of polymer brushes under confinement. The brushes consisted of either the neutral poly(ethylene oxide), PEO, or the weakly charged poly(acrylic acid), PAA. Without confinement, both PEO and PAA brushes are found to be highly swollen with water, yielding the expected parabolic brush structure. Compression of the PEO brushes with as little as 0.5 bar of confining pressure is enough to reduce the brush to a polymer block of uniform density that is significantly dehydrated (<12% v/v of water). For the charged PAA brush (at pH 9), we observe the same transition from parabolic profile to nearly dehydrated block profile, but it occurs between 1 and 5 bars of confining pressure. These experimental results are compared against a theoretical model based on numerical selfconsistent field (nSCF) theory. Whilst the nSCF model correctly predicts the observed transition from a brush to a block profile, it predicts that we should need a confining pressure a factor of 100 greater than observed in our experiments. Looking also at SFA and AFM data, we will discuss further the role of osmotic pressure in a confined polymer brush.

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

    Directory of Open Access Journals (Sweden)

    Clement C. Azodo

    2010-08-01

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

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

    OpenAIRE

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

    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-function...

  16. Piperazine-containing polymer brush layer as supported base catalyst in a glass microreactor

    OpenAIRE

    Munirathinam, Rajesh; Huskens, Jurriaan; Verboom, Willem

    2014-01-01

    The covalent attachment of piperazine onto the inner walls of a microreactor using glycidyl methacrylate polymer brushes has been demonstrated. The piperazine-containing polymer brushes were first grown on a flat silicon oxide surface and were characterized by contact angle, Fourier transform infrared (FT-IR), ellipsometry, and X-ray photoelectron spectroscopy (XPS). The applicability of the catalytic polymer brushes in a microreactor was demonstrated for the Knoevenagel and nitroaldol conden...

  17. Protein microarrays based on polymer brushes prepared via surface-initiated atom transfer radical polymerization.

    Science.gov (United States)

    Barbey, Raphael; Kauffmann, Ekkehard; Ehrat, Markus; Klok, Harm-Anton

    2010-12-13

    Polymer brushes represent an interesting platform for the development of high-capacity protein binding surfaces. Whereas the protein binding properties of polymer brushes have been investigated before, this manuscript evaluates the feasibility of poly(glycidyl methacrylate) (PGMA) and PGMA-co-poly(2-(diethylamino)ethyl methacrylate) (PGMA-co-PDEAEMA) (co)polymer brushes grown via surface-initiated atom transfer radical polymerization (SI-ATRP) as protein reactive substrates in a commercially available microarray system using tantalum-pentoxide-coated optical waveguide-based chips. The performance of the polymer-brush-based protein microarray chips is assessed using commercially available dodecylphosphate (DDP)-modified chips as the benchmark. In contrast to the 2D planar, DDP-coated chips, the polymer-brush-covered chips represent a 3D sampling volume. This was reflected in the results of protein immobilization studies, which indicated that the polymer-brush-based coatings had a higher protein binding capacity as compared to the reference substrates. The protein binding capacity of the polymer-brush-based coatings was found to increase with increasing brush thickness and could also be enhanced by copolymerization of 2-(diethylamino)ethyl methacrylate (DEAEMA), which catalyzes epoxide ring-opening of the glycidyl methacrylate (GMA) units. The performance of the polymer-brush-based microarray chips was evaluated in two proof-of-concept microarray experiments, which involved the detection of biotin-streptavidin binding as well as a model TNFα reverse assay. These experiments revealed that the use of polymer-brush-modified microarray chips resulted not only in the highest absolute fluorescence readouts, reflecting the 3D nature and enhanced sampling volume provided by the brush coating, but also in significantly enhanced signal-to-noise ratios. These characteristics make the proposed polymer brushes an attractive alternative to commercially available, 2D microarray

  18. Modeling of an oscillatory freely-rotating cutting brush for street sweeping

    OpenAIRE

    Vanegas-Useche, Libardo V; ABDEL-WAHAB, MAGD M.; Graham A. Parker

    2012-01-01

    A dynamic model of a novel oscillatory cutting brush for street sweeping in free rotation is developed. The bristles are modelled as cantilever beams. The equation of motion is determined through the theory of forced transverse vibrations of beams, and the solution is based on the normal-mode method. A sinusoidal angular speed function and a novel function, named VAP, are studied. The model is validated through finite element analyses. The effects of brush parameters on brush dynamics are ide...

  19. Pericellular Brush and Mechanics of Guinea Pig Fibroblast Cells Studied with AFM.

    Science.gov (United States)

    Dokukin, Maxim; Ablaeva, Yulija; Kalaparthi, Vivekanand; Seluanov, Andrei; Gorbunova, Vera; Sokolov, Igor

    2016-07-12

    The atomic force microscopy (AFM) indentation method combined with the brush model can be used to separate the mechanical response of the cell body from deformation of the pericellular layer surrounding biological cells. Although self-consistency of the brush model to derive the elastic modulus of the cell body has been demonstrated, the model ability to characterize the pericellular layer has not been explicitly verified. Here we demonstrate it by using enzymatic removal of hyaluronic content of the pericellular brush for guinea pig fibroblast cells. The effect of this removal is clearly seen in the AFM force-separation curves associated with the pericellular brush layer. We further extend the brush model for brushes larger than the height of the AFM probe, which seems to be the case for fibroblast cells. In addition, we demonstrate that an extension of the brush model (i.e., double-brush model) is capable of detecting the hierarchical structure of the pericellular brush, which, for example, may consist of the pericellular coat and the membrane corrugation (microridges and microvilli). It allows us to quantitatively segregate the large soft polysaccharide pericellular coat from a relatively rigid and dense membrane corrugation layer. This was verified by comparison of the parameters of the membrane corrugation layer derived from the force curves collected on untreated cells (when this corrugation membrane part is hidden inside the pericellular brush layer) and on treated cells after the enzymatic removal of the pericellular coat part (when the corrugations are exposed to the AFM probe). We conclude that the brush model is capable of not only measuring the mechanics of the cell body but also the parameters of the pericellular brush layer, including quantitative characterization of the pericellular layer structure. PMID:27410750

  20. The importance of grounding brushes to the safe operation of large turbine generators

    Energy Technology Data Exchange (ETDEWEB)

    Buckley, G.W.; Corkins, R.J.; Stephens, R.W. (The Detroit Edison Co., 2000 Second Avenue, Detroit, MI (US))

    1988-09-01

    Four sources of voltage on the shafts of large turbine generators are identified. Techniques for measuring these voltages are outlined. The consequences of not providing effective shaft grounding brushes to reduce shaft potential, the magnitude of shaft potentials, and specific components which are at risk are discussed. Recommendations for basic installation and maintenance procedures for shaft grounding brushes are made. Finally two recent unusual experiences attributed to grounding brushes are discussed.

  1. 3-D analysis of high density brush stiffness with friction-pressure coupling

    OpenAIRE

    Akşit, Mahmut Faruk; Aksit, Mahmut Faruk

    2008-01-01

    Achieving efficient sealing around high speed rotating bodies poses real engineering challenges. In recent years, dense brush structures found common use in turbomachinery sealing applications. As they maintain their flexibility at elevated temperatures, which are typical in gas turbines, high density brush seals made of super-alloy bristles found popularity among engine designers. Inherent flexibility of brush seals allows fibers to compact under pressure load. Due to the frictional interact...

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

    OpenAIRE

    Rosema, N.A.M.; Adam, R; Grender, J.M.; Sluijs, van der, E.; Supranoto, S.C.; Weijden, van der, W.J.

    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...

  3. Anion-specific effects on the behavior of pH-sensitive polybasic brushes.

    Science.gov (United States)

    Willott, Joshua D; Murdoch, Timothy J; Humphreys, Ben A; Edmondson, Steve; Wanless, Erica J; Webber, Grant B

    2015-03-31

    The anion-specific solvation and conformational behavior of weakly basic poly(2-dimethylamino)ethyl methacrylate (poly(DMA)), poly(2-diethylamino)ethyl methacrylate (poly(DEA)), and poly(2-diisopropylamino)ethyl methacrylate (poly(DPA)) brushes, with correspondingly increasing inherent hydrophobicity, have been investigated using in situ ellipsometric and quartz crystal microbalance with dissipation (QCM-D) measurements. In the osmotic brush regime, as the initial low concentration of salt is increased, the brushes osmotically swell by the uptake of solvent as they become charged and the attractive hydrophobic inter- and intrachain interactions are overcome. With increased ionic strength, the brushes move into the salted brush regime where they desolvate and collapse as their electrostatic charge is screened. Here, as the brushes collapse, they transition to more uniform and rigid conformations, which dissipate less energy, than similarly solvated brushes at lower ionic strength. Significantly, in these distinct regimes brush behavior is not only ionic strength dependent but is also influenced by the nature of the added salt based on its position in the well-known Hofmeister or lyotropic series, with potassium acetate, nitrate, and thiocyanate investigated. The strongly kosmotropic acetate anions display low affinity for the hydrophobic polymers, and largely unscreened electrosteric repulsions allow the brushes to remain highly solvated at higher acetate concentrations. The mildly chaotropic nitrate and strongly chaotropic thiocyanate anions exhibit a polymer hydrophobicity-dependent affinity for the brushes. Increasing thiocyanate concentration causes the brushes to collapse at lower ionic strength than for the other two anions. This study of weak polybasic brushes demonstrates the importance of all ion, solvent, and polymer interactions. PMID:25768282

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

    KAUST Repository

    Hutchinson, Adam J.

    2011-11-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hoyoung; Tsouris, Vasilios; Lim, Yunho; Mustafa, Rafid; Choi, Je; Choi, Yun Hwa; Park, Hae-Woong; Meron, Mati; Lin, Binhua; Won, You-Yeon [Purdue; (UC)

    2014-07-11

    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 PEO113–PnBA100 and PDMAEMA118–PnBA100, where the subscripts refer to the number-average degrees 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 PEO113–PnBA89–PDMAEMA120) 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 PEO113–PnBA100 and PDMAEMA200–PnBA103 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 PEO113–PnBA100 and PDMAEMA118–PnBA100 combination (i.e., mixed brush System #1) undergoes a lateral macroscopic phase separation

  6. Molecular interaction forces generated during protein adsorption to well-defined polymer brush surfaces.

    Science.gov (United States)

    Sakata, Sho; Inoue, Yuuki; Ishihara, Kazuhiko

    2015-03-17

    The molecular interaction forces generated during the adsorption of proteins to surfaces were examined by the force-versus-distance (f-d) curve measurements of atomic force microscopy using probes modified with appropriate molecules. Various substrates with polymer brush layers bearing zwitterionic, cationic, anionic, and hydrophobic groups were systematically prepared by surface-initiated atom transfer radical polymerization. Surface interaction forces on these substrates were analyzed by the f-d curve measurements using probes with the same polymer brush layer as the substrate. Repulsive forces, which decreased depending on the ionic strength, were generated between cationic or anionic polyelectrolyte brush layers; these were considered to be electrostatic interaction forces. A strong adhesive force was detected between hydrophobic polymer brush layers during retraction; this corresponded to the hydrophobic interaction between two hydrophobic polymer layers. In contrast, no significant interaction forces were detected between zwitterionic polymer brush layers. Direct interaction forces between proteins and polymer brush layers were then quantitatively evaluated by the f-d curve measurements using protein-immobilized probes consisting of negatively charged albumin and positively charged lysozyme under physiological conditions. In addition, the amount of protein adsorbed on the polymer brush layer was quantified by surface plasmon resonance measurements. Relatively large amounts of protein adsorbed to the polyelectrolyte brush layers with opposite charges. It was considered that the detachment of the protein after contact with the polymer brush layer hardly occurred due to salt formation at the interface. Both proteins adsorbed significantly on the hydrophobic polymer brush layer, which was due to hydrophobic interactions at the interface. In contrast, the zwitterionic polymer brush layer exhibited no significant interaction force with proteins and suppressed

  7. EUS-Guided Pancreatic Cyst Brushing: A Comparative Study in a Tertiary Referral Centre

    Directory of Open Access Journals (Sweden)

    Titus Thomas

    2010-03-01

    Full Text Available Context Fluid analysis obtained by EUS guided FNA is used to aid in diagnosis and management of cystic lesions in the pancreas. Complementing fluid aspiration with brushing of cyst wall may increase the cellular yield. Objective To compare cellular yield of pancreatic cyst FNA with and without wall brushing. Design Comparative study. Setting Tertiary referral centre. Patients Fifty-one patients with cystic pancreatic lesions referred for EUS-guided aspiration/sampling were included (median age 69 years; interquartile range: 49-77 years. Main outcome measures Comparing adequacy of cellular yield between EUS-guided aspiration alone vs. EUS-guided aspiration and cyst wall brushing. Intervention EUS-guided FNA and/or wall brushing (aspiration only: No. 27; brushing: No. 24. Results There was no significant difference in age (P=0.496 cyst size (P=0.084 or cyst location (P=0.227 between groups. Overall 29.5%; (15/51 of samples were acellular/insufficient with no significant difference between the two groups (22.2% in the aspiration only group vs. 37.5% in the brushing group; P=0.356. The remaining samples were adequate for cytological evaluation (77.8% vs. 62.5%; aspiration only vs. brushing groups. Seventeen cases were neoplastic (8 benign, 9 malignant. The diagnostic accuracy was 61.9% and 55.0% in aspiration only and brushing groups, respectively. Two out of 4 (50.0% patents were diagnosed as having cancer in the brushings group compared to 1/5 (20.0% in the FNA only group (P=0.524. Limitations Non-randomised series. Conclusions The cellular yield was similar in FNA and brushing group. Greater proportion of patients with malignant cystic pancreatic lesions diagnosed by EUS sampling was in the brushing group, but this did not reach statistical significance.

  8. Testing of the LORI stiff brush skimmer sweep system

    International Nuclear Information System (INIS)

    A new concept utilizing a sweep system in conjunction with stiff cylindrical brushes mounted on an endless chain has been developed for recovering heavy oils and emulsions from water surfaces. One such system, the LORI Side Collector system, was quantitatively tested in an indoor wave tank using diesel, crude oil, emulsified crude, and bunker oil. The skimmer was tested in 4 degree C water at current velocities in the 0.15-0.65 m/s range, in calm water conditions, and in waves of 5-7 cm height. The brush speed was varied between 6 and 30 cm/s. The skimmer was evaluated in terms of fluid recovery rate and oil recovery rate. The maximum capacity of the skimmer may not have been reached due to current velocity limitations of the tank. The effect of brush speed and oil encounter rate were determined. Skimmer performance increased with increasing oil viscosity. Higher current speeds and waves also enhanced recovery. Following the tank trials, the system was installed on a 8.5 m sea truck and trials were conducted on the St. Lawrence River. These tests assessed the stability, maneuverability, sea keeping, and operation of the system. Oil was not used in these tests, but the system was evaluated as to its ability to deal with debris and to direct an oil-substitute towards and into the skimmer entrance. In general, the skimmer did not adversely hamper the maneuverability of the sea truck. The oil-substitute was satisfactorily recovered at velocities up to 1.5-2 m/s. 13 figs., 4 tabs

  9. Electrotechnics - AC motors. Asynchronous and brush-less motors - Lecture and exercises with solutions; Electrotechnique - Moteurs a courant alternatif. Moteurs asynchrones et brushless - Cours et problemes resolus

    Energy Technology Data Exchange (ETDEWEB)

    Jacob, D.

    2005-07-01

    This book proposes a presentation of AC electric motors essentially based on physics and technology. Its originality consists in avoiding to use mathematical formulations (like Park's transformation). The modeling retained, which only uses magnetic momentum, magnetic fields and reluctance concepts, leads simply and naturally to the vectorial control principle. The book develops some lecture elements which includes some topics rarely considered like the dimensioning of an asynchronous motor or of a single-phase brush-less motor. Experimental results illustrate the physical phenomena described and many original problems are resolved and commented at the end of each chapter. Content: signals and systems in electrotechnics, torque and rotating magnetic fields generation, asynchronous machine in permanent regime, speed variation of the asynchronous motor, special asynchronous motors, synchronous machine in permanent regime, brush-less motor, note about step motors, note about inverters, index. (J.S.)

  10. Electrochemical redox responsive polymeric micelles formed from amphiphilic supramolecular brushes.

    Science.gov (United States)

    Feng, Anchao; Yan, Qiang; Zhang, Huijuan; Peng, Liao; Yuan, Jinying

    2014-05-11

    The end-decorated homopolymer poly(ε-caprolactone)-ferrocene threaded onto a β-cyclodextrin-functionalized main-chain polymer can form a class of amphiphilic noncovalent graft copolymers based on the host-guest interactions of the terminal groups on the side chains. These new supramolecular polymer brushes can further self-assemble into micellar aggregates that exhibit reversible assembly and disassembly behavior under an electrochemical redox trigger, which opens up a new route to building dynamic block copolymer topologies. PMID:24681929

  11. Parents experiences of tooth brushing with children: a qualitative study

    OpenAIRE

    Marshmann, Z; Ahern, SM; McEachen, RRC; Rogers, HJ.; Gray-Burrows, KA; Day, PF

    2016-01-01

    Globally, dental caries is one of the most prevalent diseases and is more common in children living in deprived areas. Dental caries is preventable, and guidance in the United Kingdom recommends parental supervised brushing (PSB): a collection of behaviors—including twice-daily toothbrushing with fluoridated toothpaste—that should begin upon eruption of the first tooth (approximately 6 to 12 mo of age) and for which children need to be helped or supervised by an adult until at least 7 y of ag...

  12. A Modified Tactile Brush Algorithm for Complex Touch Gestures

    Energy Technology Data Exchange (ETDEWEB)

    Ragan, Eric [Texas A& M University

    2015-01-01

    Several researchers have investigated phantom tactile sensation (i.e., the perception of a nonexistent actuator between two real actuators) and apparent tactile motion (i.e., the perception of a moving actuator due to time delays between onsets of multiple actuations). Prior work has focused primarily on determining appropriate Durations of Stimulation (DOS) and Stimulus Onset Asynchronies (SOA) for simple touch gestures, such as a single finger stroke. To expand upon this knowledge, we investigated complex touch gestures involving multiple, simultaneous points of contact, such as a whole hand touching the arm. To implement complex touch gestures, we modified the Tactile Brush algorithm to support rectangular areas of tactile stimulation.

  13. Investigation of brush seals for application in steam turbines

    International Nuclear Information System (INIS)

    Brush seals have high potential for efficiency increase compared to conventional labyrinth seals in steam turbines. Due to less experience in operation today there is a lot of scepticism with customers of steam turbine manufacturers. Therefore this thesis is investigating characteristics of this type of seal. Experiments and numerical models will be presented, which lead to better knowledge about leakages and influence of flow through seal onto dynamics of rotor in comparison to labyrinth seals. This thesis is increasing area of experience and one more positive reference.

  14. Piperazine-containing polymer brush layer as supported base catalyst in a glass microreactor

    NARCIS (Netherlands)

    Munirathinam, Rajesh; Huskens, Jurriaan; Verboom, Willem

    2014-01-01

    The covalent attachment of piperazine onto the inner walls of a microreactor using glycidyl methacrylate polymer brushes has been demonstrated. The piperazine-containing polymer brushes were first grown on a flat silicon oxide surface and were characterized by contact angle, Fourier transform infrar

  15. A Colorimetric Interdental Probe as a Standard Method to Evaluate Interdental Efficiency of Interdental Brush

    Science.gov (United States)

    Bourgeois, D.; Carrouel, F.; Llodra, J.C.; Bravo, M.; Viennot, S.

    2015-01-01

    The aim of this study is to evaluate the concordance between the empirical choice of interdental brushes of different diameters compared to the gold standard, the IAP CURAPROX© calibrating colorimetric probe. It is carried out with the aim of facilitating the consensus development of best practices. All the subjects’ interproximal spaces were evaluated using the reference technique (colorimetric probe), then after a time lapse of 1.2 ± 0.2 hours, using the empirical clinical technique (brushes) by the same examiner. Each examiner explored 3 subjects. The order the patients were examined with the colorimetric interdental probe (CIP) was random. 446 sites were selected in the study out of 468 potential sites. The correspondence of scores between interdental bushes vs. colorimetric probe is 43.0% [95%-CI: 38.5-47.6]. In 33.41% of the 446 sites, the brush is inferior to the probe; in 23.54% of cases, the brush is superior to the probe. Among the discrepancies there is thus a tendency for the subjects to use brushes with smaller diameter than that recommended by the colorimetric probe. This review has found very high-quality evidence that colorimetric probes plus interdental brushing is more beneficial than interdental brushing alone for increase the concordance between the empirical choice of interdental brushes of different diameters compared to the gold standard. Uncertainties remain and further research is required to provide detailed data on user satisfaction. PMID:26966470

  16. Preparation and Friction Force Microscopy Measurements of Immiscible, Opposing Polymer Brushes

    NARCIS (Netherlands)

    Beer, de S.; Kutnyanszky, E.; Müser, M.H.; Vancso, G.J.

    2014-01-01

    Solvated polymer brushes are well known to lubricate high-pressure contacts, because they can sustain a positive normal load while maintaining low friction at the interface. Nevertheless, these systems can be sensitive to wear due to interdigitation of the opposing brushes. In a recent publication,

  17. Elastic repulsion from polymer brush layers exhibiting high protein repellency.

    Science.gov (United States)

    Inoue, Yuuki; Nakanishi, Tomoaki; Ishihara, Kazuhiko

    2013-08-27

    Hydrophilic poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) and poly(2-hydroxyethyl methacrylate) (PHEMA) brush layers with different thicknesses and graft densities were prepared to construct a model surface to elucidate protein-surface interactions. In particular, we focused on the steric repulsion of hydrophilic polymer layers as one of the surface properties that strongly influence protein adsorption and employed force-versus-distance (f-d) curve measurements obtained via atomic force microscopy to quantitatively evaluate the steric repulsion force, which is also referred to as the "elastic repulsion energy." We also analyzed direct interactions between the surface and proteins via the f-d curve, because these interactions trigger the protein-adsorption phenomenon. Protein-surface interactions were extremely suppressed at surfaces with high elastic repulsion energies and highly dense polymer brush structures, which is in contrast to those at surfaces with low elastic repulsion energies and low density of the grafted polymer layers. These results indicate that the elastic repulsion from the grafted polymer layer at the surface is an important parameter for controlling protein-surface interactions and protein adsorption phenomenon. PMID:23898820

  18. Graphene transistors with multifunctional polymer brushes for biosensing applications.

    Science.gov (United States)

    Hess, Lucas H; Lyuleeva, Alina; Blaschke, Benno M; Sachsenhauser, Matthias; Seifert, Max; Garrido, Jose A; Deubel, Frank

    2014-06-25

    Exhibiting a combination of exceptional structural and electronic properties, graphene has a great potential for the development of highly sensitive sensors. To date, many challenging chemical, biochemical, and biologic sensing tasks have been realized based on graphene. However, many of these sensors are rather unspecific. To overcome this problem, for instance, the sensor surface can be modified with analyte-specific transducers such as enzymes. One problem associated with the covalent attachment of such biomolecular systems is the introduction of crystal defects that have a deleterious impact on the electronic properties of the sensor. In this work, we present a versatile platform for biosensing applications based on polymer-modified CVD-grown graphene transistors. The functionalization method of graphene presented here allows one to integrate several functional groups within surface-bound polymer brushes without the introduction of additional defects. To demonstrate the potential of this polymer brush functionalization scaffold, we modified solution-gated graphene field-effect transistors with the enzyme acetylcholinesterase and a transducing group, allowing the detection of the neurotransmitter acetylcholine. Taking advantage of the transducing capability of graphene transistors and the versatility of polymer chemistry and enzyme biochemistry, this study presents a novel route for the fabrication of highly sensitive, multipurpose transistor sensors that can find application for a multitude of biologically relevant analytes. PMID:24866105

  19. Lectin binding studies on a glycopolymer brush flow-through biosensor by localized surface plasmon resonance.

    Science.gov (United States)

    Rosencrantz, Ruben R; Nguyen, Vu Hoa; Park, Hyunji; Schulte, Christine; Böker, Alexander; Schnakenberg, Uwe; Elling, Lothar

    2016-08-01

    A localized surface plasmon resonance biosensor in a flow-through configuration was applied for investigating kinetics of lectin binding to surface-grafted glycopolymer brushes. Polycarbonate filter membranes with pore sizes of 400 nm were coated with a 114-nm thick gold layer and used as substrate for surface-initiated atom-transfer radical polymerization of a glycomonomer. These grafted from glycopolymer brushes were further modified with two subsequent enzymatic reactions on the surface to yield an immobilized trisaccharide presenting brush. Specific binding of lectins including Clostridium difficile toxin A receptor domain to the glycopolymer brush surface could be investigated in a microfluidic setup with flow-through of the analytes and transmission surface plasmon resonance spectroscopy. Graphical abstract Glycopolymer brushes serve as high affinity ligands for lectin and toxin interactions in a sensitive, disposable flow-through LSPR biosensor. PMID:27277814

  20. Tooth brushing pattern classification using three-axis accelerometer and magnetic sensor for smart toothbrush.

    Science.gov (United States)

    Lee, Kang-Hwi; Lee, Jeong-Whan; Kim, Kyeong-Seop; Kim, Dong-Jun; Kim, Kyungho; Yang, Heui-Kyung; Jeong, Keesam; Lee, Byungchae

    2007-01-01

    The concept of intelligent toothbrush, capable of monitoring brushing motion, orientation through the grip axis, during toothbrushing was suggested in our previous study. In this study, we describe a tooth brushing pattern classification algorithm using three-axis accelerometer and three-axis magnetic sensor. We have found that inappropriate tooth brushing pattern showed specific moving patterns. In order to trace the position and orientation of toothbrush in a mouth, we need to know absolute coordinate information of toothbrush. By applying tilt-compensated azimuth (heading) calculation algorithm, which is generally used in small telematics devices, we could find the inclination and orientation information of toothbrush. To assess the feasibility of the proposed algorithm, 8 brushing patterns were preformed by 6 individual healthy subjects. The proposed algorithm showed the detection ratio of 98%. This study showed that the proposed monitoring system was conceived to aid dental care personnel in patient education and instruction in oral hygiene regarding brushing style. PMID:18002931

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

    DEFF Research Database (Denmark)

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

    2009-01-01

    The small intestinal brush border functions as the body's main portal for uptake of dietary nutrients and simultaneously acts as the largest permeability barrier against pathogens. To enable this, the digestive enzymes of the brush border are organized in lipid raft microdomains stabilized by cross...... incorporated into the brush border, and by 15 min faint but distinct punctae were detectable about 1 m beneath the brush border, indicative of a constitutive endocytosis. The punctae represented a subpopulation of early endosomes confined to the actomyosin-rich terminal web region, and their number...... localized deeper into the cytoplasm of the enterocytes. Two major raft-associated brush border enzymes, alkaline phosphatase and aminopeptidase N, were excluded from endocytosis. We propose that the terminal web cytoskeleton, by inhibiting traffic from apical early endosomes further into the cell...

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

    Directory of Open Access Journals (Sweden)

    Pordeus Isabela A

    2011-09-01

    Full Text Available Abstract 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 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, indicative of reporting bias. Data regarding children's tooth-brushing habits as reported by mothers should be considered with caution in epidemiological surveys on fluoridated dentifrice use and the risk of dental fluorosis.

  3. Tooth brushing skills for the children aged 3-11 years

    Directory of Open Access Journals (Sweden)

    Das U

    2009-06-01

    Full Text Available Objectives: The objective of this study was to evaluate tooth brushing management and ability of children in relation to age and gender. Materials and Methods: The study population consisted of 45 children, who attended Department of Pedodontics and Preventive Dentistry at V.S Dental College and Hospital Bangalore. Children were divided into three groups according to age: Group I: 3-5 years, Group II: 6-8 years, and Group III: 9-11 years. Each child selected his/her favorite toothbrush and brushed his/her teeth under supervision of one instructor. The grip type during tooth brushing was recorded on a videotape and duration of tooth brushing also was noted. The data were analyzed in relation to the age and gender using the chi-square test. ANOVA was used to find if there is any significant difference between the mean brushing times in the different groups. Results: The results of statistical analysis showed that in all cases P> 0.05 for grip preferences and P < 0.001 between age groups 3-5 years and 9-11 years with respect to the mean brushing time. Conclusion: The required manual dexterity for tooth brushing was present in younger age groups.

  4. Enhanced stability of low fouling zwitterionic polymer brushes in seawater with diblock architecture.

    Science.gov (United States)

    Quintana, Robert; Gosa, Maria; Jańczewski, Dominik; Kutnyanszky, Edit; Vancso, G Julius

    2013-08-27

    The successful implementation of zwitterionic polymeric brushes as antifouling materials for marine applications is conditioned by the stability of the polymer chain and the brush-anchoring segment in seawater. Here we demonstrate that robust, antifouling, hydrophilic polysulfobetaine-based brushes with diblock architecture can be fabricated by atom-transfer radical polymerization (ATRP) using initiator-modified surfaces. Sequential living-type polymerization of hydrophobic styrene or methyl methacrylate and commercially available hydrophilic sulfobetaine methacrylamide (SBMAm) monomer is employed. Stability enhancement is accomplished by protecting the siloxane anchoring bond of brushes on the substrate, grafted from silicon oxide surfaces. The degradation of unprotected PSBMAm brushes is clearly evident after a 3 month immersion challenge in sterilized artificial seawater. Ellipsometry and atomic force microscopy (AFM) measurements are used to follow changes in coating thickness and surface morphology. Comparative stability results indicate that surface-tethered poly(methyl methacrylate) and polystyrene hydrophobic blocks substantially improve the stability of zwitterionic brushes in an artificial marine environment. In addition, differences between the hydration of zwitterionic brushes in fresh and salt water are discussed to provide a better understanding of hydration and degradation processes with the benefit of improved design of polyzwitterionic coatings. PMID:23876125

  5. The effectivity of toothpick tooth brushing method on plaque control

    Directory of Open Access Journals (Sweden)

    Chiquita Prahasanti

    2011-06-01

    Full Text Available Background: Periodontal diseases are associated with bacteria species which present in biofilms that colonize on dental surfaces. Several tooth brushing methods had been known and proved to be effective in maintaining oral hygiene. Among them, tooth pick technique was a relatively new method and its superiority in removing interproximal plaque was better than other methods. Purpose: The purpose of this study was to examine the effectivity of toothpick tooth brushing method to conventional method on periodontal health. Methods: This research was designed as an analytical observational study. Thirty samples selected from five hundred and twelve males Indonesian Air-force members in Malang, aged 18–40 yrs, with periodontal pockets (≤ 5 mm in upper or lower teeth, without crowding, gingival index minimal > 1 (moderate gingivitis, OHI-S score minimal ≥ 1.3 (moderate, without systemic diseases, do not undergone medical therapy/drug prescriptions, without using mouth rinse during study, and without prosthesis. There were thirty samples in this research and devided to two groups, fifteen samples easch. The groups were toothpick tooth brusing method and conventional method (control group. In this study oral hygiene index simplified (OHI-S, gingival index (GI, bleeding on probing (BOP and pocket depth were examined. Results: There were significant differences (p = .001 in OHI-S, GI, BOP, and PD before and after conducting each toothbrushing method, as well as differences between means (quarrel means, that were p = .003; p = .001; p = .001 and p = .001 consecutively. Conclusion: Toothpick brushing method was more effective in plaque control compared to conventional method.Latar belakang: Penyakit periodontal berhubungan dengan bakteri yang berkoloni dalam biofilm yang terdapat di permukaan gigi. Saat ini telah dikenal berbagai macam metode menyikat gigi tetapi masih belum ada penelitian tentang efek metode tersebut terhadap OHI-S. Penelitian in ingin

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

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Jiuzhou [Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Zhang, Xinghua, E-mail: zhangxh@bjtu.edu.cn [School of Science, Beijing Jiaotong University, Beijing 100044 (China); Yan, Dadong, E-mail: yandd@bnu.edu.cn [Department of Physics, Beijing Normal University, Beijing 100875 (China)

    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 bending 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.

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

    Science.gov (United States)

    Berning, Robert H.; Viout, Olivier

    2010-01-01

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

  8. Positron annihilation spectroscopy: a new frontier for understanding nanoparticle-loaded polymer brushes

    Science.gov (United States)

    Panzarasa, Guido; Aghion, Stefano; Soliveri, Guido; Consolati, Giovanni; Ferragut, Rafael

    2016-01-01

    Nanoparticle-loaded polymer brushes are powerful tools for the development of innovative devices. However, their characterization is challenging and arrays of different techniques are typically required to gain sufficient insight. Here we demonstrate for the first time the suitability of positron annihilation spectroscopy (PAS) to investigate, with unprecedented detail and without making the least damage to samples, the physico-chemical changes experienced by pH-responsive polymer brushes after protonation and after loading of silver nanoparticles. One of the most important findings is the depth profiling of silver nanoparticles inside the brushes. These results open up a completely new way to understand the structure and behavior of such complex systems.

  9. Wire grill brush bristle as an unusual foreign body: report of two pediatric cases.

    Science.gov (United States)

    Arganbright, Jill M; Bruegger, Daniel E; Sykes, Kevin J; Wei, Julie L

    2012-03-01

    Wire grill brushes are commonly used for cleaning grill grates. Accidental ingestion of a wire bristle from a grill-cleaning brush is a rarely reported foreign body, with only three prior case reports. Although scarce in the literature, we encountered two pediatric cases at the regional children's hospital within 1 year. By presenting these two cases, our goal was to raise awareness of this potentially hazardous foreign body. Additionally, we raise a consumer safety issue associated with the use of wire grill-cleaning brushes as there are currently no ingestion hazard warnings on these products. Laryngoscope,, 2011. PMID:22231656

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    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...

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

    Directory of Open Access Journals (Sweden)

    Indriasti Indah Wardhany

    2013-07-01

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

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

    Science.gov (United States)

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

    2009-03-01

    Though brushes are no longer used on the hands and forearms during the surgical scrub, they are still widely used on the nails. The aim of this study was to determine whether nail picks and nail brushes are effective in providing additional decontamination during a surgical hand scrub. A total of 164 operating department staff were randomised to undertake one of the following three surgical hand-scrub protocols: chlorhexidine only; chlorhexidine and a nail pick; or chlorhexidine and a nail brush. Bacterial hand sampling was conducted before and 1h after scrubbing using a modified version of the glove juice method. No statistically significant differences in bacterial numbers were found between any two of the three intervention groups. Nail brushes and nail picks used during surgical hand scrubs do not decrease bacterial numbers and are unnecessary. PMID:19162371

  13. Annealing-free fabrication of P3HT:PCBM solar cells via simple brush painting

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seok-Soon [Department of Nano and Chemical Engineering, Kunsan National University, 1170 University Avenue, Kunsan, Jeollabuk-do, 753-701 (Korea); Na, Seok-In; Kang, Seok-Ju; Kim, Dong-Yu. [Heeger Center for Advanced Materials, Department of Materials Science and Engineering, Gwangju Institute of Science and Technology, 1 Oryoung-dong, Gwangju 500-712 (Korea)

    2010-02-15

    We report on the fabrication of efficient annealing-free polymer solar cells via simple brush painting considered as a promising method for the mass production of organic devices based on the high-speed roll-to-roll system. Higher device efficiency could be obtained compared to the spin-coated devices, resulting from the improved organization of polymer chains and better balanced carrier transport induced by more effective application of shear stress to the polymer chains during the brushing process. In addition, fully brush painted solar cells, including the brush-painted PEDOT:PSS and photoactive layer, presented a high power conversion efficiency of 3.6% without any annealing treatment and processing additives. (author)

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

    Directory of Open Access Journals (Sweden)

    Rajesh Munirathinam

    2013-08-01

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

  15. Efficacy of plaque-removal using interdental brushes and waxed dental floss.

    Science.gov (United States)

    Bergenholtz, A; Olsson, A

    1984-06-01

    The plaque-removing efficacy when using waxed dental floss and three interdental brushes was compared in an intraindividual clinical trial. Nine adult patients treated for periodontal disease, with a reduced but healthy periodontium and large interdental spaces were subjects in the study. Each subject tested the four interdental cleaning aids in random sequence over a 2-wk period. The duration of the study was 8 wk. The results indicated that the use of interdental brushes is preferable to that of dental floss in cleaning interdental areas where the papilla is missing. No difference in achieved cleanliness was noted after use of the different interdental brushes tested. No gingival damage or damage to the hard tissue of the teeth was observed after use of interdental brushes or dental floss. PMID:6589735

  16. Brush in the bath of active particles: Anomalous stretching of chains and distribution of particles

    Science.gov (United States)

    Li, Hui-shu; Zhang, Bo-kai; Li, Jian; Tian, Wen-de; Chen, Kang

    2015-12-01

    The interaction between polymer brush and colloidal particles has been intensively studied in the last two decades. Here, we consider a flat chain-grafted substrate immersed in a bath of active particles. Simulations show that an increase in the self-propelling force causes an increase in the number of particles that penetrate into the brush. Anomalously, the particle density inside the main body of the brush eventually becomes higher than that outside the brush at very large self-propelling force. The grafted chains are further stretched due to the steric repulsion from the intruded particles. Upon the increase of the self-propelling force, distinct stretching behaviors of the chains were observed for low and high grafting densities. Surprisingly, we find a weak descent of the average end-to-end distance of chains at high grafting density and very large force which is reminiscent of the compression effect of a chain in the active bath.

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

    Directory of Open Access Journals (Sweden)

    Dikran Kesal

    2016-04-01

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

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

    OpenAIRE

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

    2012-01-01

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

  19. New Development of Monte Carlo Techniques for Studying Bottle-brush Polymers

    OpenAIRE

    Hsu, Hsiao-Ping

    2011-01-01

    Due to the complex characteristics of bottle-brush polymers, it became a challenge to develop an efficient algorithm for studying such macromolecules under various solvent conditions or some constraints in the space by using computer simulations. In the limit of a bottle-brush polymer with a rather stiff backbone (straight rigid backbone), we generalize the variant of the biased chain growth algorithm, the pruned-enriched Rosenbluth method, for simulating polymers with complex architecture, f...

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

    DEFF Research Database (Denmark)

    Danielsen, E M

    1989-01-01

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

  1. Flow and thermal analysis of oil brush seals, and investigation of shear heating phenomenon

    OpenAIRE

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

    2012-01-01

    Due to their superior performance and stable leakage characteristics, brush seal is one of the emerging seals to be used in oil and oil mist applications in aero-engines and turbines. The viscous medium between the high speed rotor surface and bearing surfaces formed by brush seal bristles generates a hydrodynamic lifting force that determines seal clearance and leakage rate in oil sealing applications. The analytical solution to bristle lifting force can be found by using Reynolds formulatio...

  2. Effect of shear heat on hydrodynamic lift of brush seals in oil sealing

    OpenAIRE

    Duran, Ertuğrul Tolga; Duran, Ertugrul Tolga; Akşit, Mahmut Faruk; Aksit, Mahmut Faruk; Doğu, Yahya; Dogu, Yahya

    2006-01-01

    Due to their superior performance and stable leakage characteristics, brush seals are one of the dynamic seals used in oil and oil mist applications in aero-engines and turbines. The viscous medium between the high speed rotor surface and bearing surfaces formed by brush seal bristles generates a hydrodynamic lifting force that determines seal clearance and leakage rate in oil sealing applications. The analytical solution to bristle lifting force can be found by using Reynolds formulation. Fo...

  3. A study of brush seal oil pressure profile including temperature-viscosity effects

    OpenAIRE

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

    2008-01-01

    After proven performance in air applications, brush seals are being considered for oil and oil mist sealing in aero-engines, turbines and generators. The viscous medium between the high speed rotor surface and bearing surfaces formed by brush seal bristle tips generates a hydrodynamic lifting force that determines seal clearance and leakage rate in oil sealing applications. Hydrodynamic lift force and seal clearance have strong dependence on oil temperature and viscosity. In a previous study,...

  4. Association of anionic surfactant and physisorbed branched brush layers probed by neutron and optical reflectometry

    OpenAIRE

    Liu, Xiaoyan; Dédinaité, Andra; Nylander, Tommy; Dabkowska, Aleksandra P.; Skoda, Maximilian; Makuska, Ricardas; Claesson, Per Martin

    2015-01-01

    Pre-adsorbed branched brush layers were formed on silica surfaces by adsorption of a diblock copolymer consisting of a linear cationic block and an uncharged bottle-brush block. The charge of the silica surface was found to affect the adsorption, with lower amounts of the cationic polyelectrolyte depositing on less charged silica. Cleaning under basic conditions rendered surfaces more negatively charged (more negative zeta-potential) than acid cleaning and was therefore used to increase polye...

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

    OpenAIRE

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

    2011-01-01

    Abstract 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 mo...

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

    KAUST Repository

    Zhang, Hefeng

    2014-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    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.

  8. EUV Radiation Grafting of Nanostructured Polymer Brushes by Raft-Mediated Polymerization

    International Nuclear Information System (INIS)

    EUV (extreme ultraviolet) interference lithographic exposure of polymer substrates followed by graft polymerization of a second polymer is a powerful technique to form periodic patterns of polymer brushes with nanometer scale resolution. In this work EUV interference exposures were used to create periodic patterns of radicals at the surface of fluoropolymer films serving as initiators for the reverse addition-fragmentation chain transfer (RAFT)-mediated graft polymerization of nanostructured polymer brushes with the help of dithiobenzoates as chain transfer agents (CTAs). The RAFT-mediated polymerization scheme allows us to get monodisperse brushes and to tune their molecular weight. Nanostructured polymer brushes down to 100 nm period were achieved. Nanostructured polymer brushes with 'living' ends were used as macro-CTAs to tailor block-copolymers. We observed difference in heights, shapes and morphologies between grafted brushes and the grafted block-copolymers with atomic force microscopy (AFM) and scanning electron microscopy (SEM). The lithographic RAFT-mediated grafting process can be transferred to many combinations of polymer supports and grafted monomers, enabling the preparation of a huge variety of grafted polymers, block-copolymers and functional polymer structures with selected properties

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

    Science.gov (United States)

    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

  10. Novel temperature-responsive polymer brushes with carbohydrate residues facilitate selective adhesion and collection of hepatocytes

    Directory of Open Access Journals (Sweden)

    Naokazu Idota, Mitsuhiro Ebara, Yohei Kotsuchibashi, Ravin Narain and Takao Aoyagi

    2012-01-01

    Full Text Available Temperature-responsive glycopolymer brushes were designed to investigate the effects of grafting architectures of the copolymers on the selective adhesion and collection of hypatocytes. Homo, random and block sequences of N-isopropylacrylamide and 2-lactobionamidoethyl methacrylate were grafted on glass substrates via surface-initiated atom transfer radical polymerization. The galactose/lactose-specific lectin RCA120 and HepG2 cells were used to test for specific recognition of the polymer brushes containing galactose residues over the lower critical solution temperatures (LCSTs. RCA120 showed a specific binding to the brush surfaces at 37 °C. These brush surfaces also facilitated the adhesion of HepG2 cells at 37 °C under nonserum conditions, whereas no adhesion was observed for NIH-3T3 fibroblasts. When the temperature was decreased to 25 °C, almost all the HepG2 cells detached from the block copolymer brush, whereas the random copolymer brush did not release the cells. The difference in releasing kinetics of cells from the surfaces with different grafting architectures can be explained by the correlated effects of significant changes in LCST, mobility, hydrophilicity and mechanical properties of the grafted polymer chains. These findings are important for designing 'on–off' cell capture/release substrates for various biomedical applications such as selective cell separation.

  11. Putative interaction of brush cells with bicarbonate secreting cells in the proximal corpus mucosa

    Directory of Open Access Journals (Sweden)

    Julia Anna-Maria Eberle

    2013-07-01

    Full Text Available The gastric epithelium is protected from the highly acidic luminal content by alkaline mucus which is secreted from specialized epithelial cells. In the stomach of mice strong secretion of alkaline fluid was observed at the gastric groove, the border between corpus and fundus mucosa. Since this region is characterized by numerous brush cells it was proposed that these cells might secrete alkaline solution as suggested for brush cells in the bile duct. In fact, it was found that in this region multiple cells express elements which are relevant for the secretion of bicarbonate, including carbonic anhydrase (CAII, the cystic fibrosis transmembrane conductance regulator (CFTR and the Na+/H+ exchanger (NHE1. However, this cell population was distinct from brush cells which express the TRP-channel TRPM5 and are considered as putative sensory cells. The location of both cell populations in close proximity implies the possibility for a paracrine interaction. This view was substantiated by the finding that brush cells express prostaglandin synthase-1 (COX-1 and the neighbouring cells a specific receptor type for prostaglandins. The notion that brush cells may be able to sense a local acidification was supported by the observation that they express the channel PKD1L3 which contributes to the acid responsiveness of gustatory sensory cells. The results support the concept that brush cells may sense the luminal content and influence via prostaglandins the secretion of alkaline solution.

  12. Membrane-enhanced surface acoustic wave analysis of grafted polymer brushes

    Science.gov (United States)

    Brass, David A.; Shull, Kenneth R.

    2008-04-01

    An analysis is developed for the frequency response of a quartz crystal resonator (often referred to as a quartz crystal microbalance) that is modified with a grafted solvent-swollen polymer brush and placed in contact with a membrane capping layer. The shear wave generated at the resonator surface couples into the membrane layer with an efficiency that is strongly dependent on the thickness of the swollen brush layer. As a result, the resonant frequency changes by a maximum amount that is closely approximated by the Sauerbrey shift for the capping layer. The calculated shift substantially decreases for increases in the brush thickness of approximately 10nm, which gives a net frequency response that is extremely sensitive to the degree of swelling of the polymer brush. An optimum capping layer thickness is determined by balancing the Sauerbrey shift against dissipative effects that weaken the crystal resonance. This optimum membrane thickness depends only weakly on the properties of the membrane material and is in the micron range. Detailed multilayer calculations are presented for the specific case of a poly(ethylene glycol) brush swollen with water and brought into contact with an elastomeric water-permeable membrane. These calculations confirm that the method is sensitive to the properties of the brush layer in the experimentally relevant thickness regime. Connections are also made to conceptually simpler two and three layer models of the acoustic impedance of the material systems that are brought into contact with the resonator.

  13. Preparation and friction force microscopy measurements of immiscible, opposing polymer brushes.

    Science.gov (United States)

    de Beer, Sissi; Kutnyanszky, Edit; Müser, Martin H; Vancso, G Julius

    2014-01-01

    Solvated polymer brushes are well known to lubricate high-pressure contacts, because they can sustain a positive normal load while maintaining low friction at the interface. Nevertheless, these systems can be sensitive to wear due to interdigitation of the opposing brushes. In a recent publication, we have shown via molecular dynamics simulations and atomic force microscopy experiments, that using an immiscible polymer brush system terminating the substrate and the slider surfaces, respectively, can eliminate such interdigitation. As a consequence, wear in the contacts is reduced. Moreover, the friction force is two orders of magnitude lower compared to traditional miscible polymer brush systems. This newly proposed system therefore holds great potential for application in industry. Here, the methodology to construct an immiscible polymer brush system of two different brushes each solvated by their own preferred solvent is presented. The procedure how to graft poly(N-isopropylacrylamide) (PNIPAM) from a flat surface and poly(methyl methacrylate) (PMMA) from an atomic force microscopy (AFM) colloidal probe is described. PNIPAM is solvated in water and PMMA in acetophenone. Via friction force AFM measurements, it is shown that the friction for this system is indeed reduced by two orders of magnitude compared to the miscible system of PMMA on PMMA solvated in acetophenone. PMID:25590429

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

    Science.gov (United States)

    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.

  15. Polarizing intestinal epithelial cells electrically through Ror2

    OpenAIRE

    Cao, L; McCaig, CD; Scott, RH; Zhao, S.; G. Milne; Clevers, H; Zhao, M; Pu, J

    2014-01-01

    ABSTRACT The apicobasal polarity of enterocytes determines where the brush border membrane (apical membrane) will form, but how this apical membrane faces the lumen is not well understood. The electrical signal across the epithelium could serve as a coordinating cue, orienting and polarizing enterocytes. Here, we show that applying a physiological electric field to intestinal epithelial cells, to mimic the natural electric field created by the transepithelial potential difference, polarized p...

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

    International Nuclear Information System (INIS)

    A purified fraction of proximal tubule brush border membranes (BBM) was prepared from dog kidney and used to immunize mice. The standard technique of hybridoma production was followed as described by Kohler and Milstein. Production of antibodies was detected by indirect immunofluorescence on dog kidney slices and by immunodot against the purified fraction on nitrocellulose. Five hybrids exhibited anti BBM activity. These were cloned twice and yielded stable cell lines producing IgG type monoclonal antibodies against BBM. They were designated A1, C7, D3, D7 and H4. As a family these five monoclonals have broad tissue specificity, i.e. positive staining of the surface mucosa of intestinal kidney proximal tubules. D3 exhibits even broader specificity for epithelium reacting with bile canaliculi and choroid plexus. The authors have verified that at least 4/5 antibodies are directed against BBM protein as revealed by immunoprecipitation of solubilized BBM and detected by Coomassie blue staining or autoradiography of lactoperoxidase labelled BBM. Most interestingly all antibodies bind to the surface of LL CPK1 cells, a continuous pig kidney cell line of undefined origin but exhibiting many characteristics of proximal tubule cells. The library of monoclonal antibodies obtained provide important probes with which to study membrane biogenesis and polarization in epithelial cells

  17. Tuning ice nucleation with counterions on polyelectrolyte brush surfaces

    Science.gov (United States)

    He, Zhiyuan; Xie, Wen Jun; Liu, Zhenqi; Liu, Guangming; Wang, Zuowei; Gao, Yi Qin; Wang, Jianjun

    2016-01-01

    Heterogeneous ice nucleation (HIN) on ionic surfaces is ubiquitous in a wide range of atmospheric aerosols and at biological interfaces. Despite its great importance in cirrus cloud formation and cryopreservation of cells, organs, and tissues, it remains unclear whether the ion-specific effect on ice nucleation exists. Benefiting from the fact that ions at the polyelectrolyte brush (PB)/water interface can be reversibly exchanged, we report the effect of ions on HIN on the PB surface, and we discover that the distinct efficiency of ions in tuning HIN follows the Hofmeister series. Moreover, a large HIN temperature window of up to 7.8°C is demonstrated. By establishing a correlation between the fraction of ice-like water molecules and the kinetics of structural transformation from liquid- to ice-like water molecules at the PB/water interface with different counterions, we show that our molecular dynamics simulation analysis is consistent with the experimental observation of the ion-specific effect on HIN. PMID:27386581

  18. Application of polymer brush prepared by RIGP to enzyme immobilization

    International Nuclear Information System (INIS)

    A diethylamino-group-containing polymer brush was grafted onto a porous hollow-fiber membrane by radiation-induced graft polymerization (RIGP) of an epoxy group-containing vinyl monomer, followed by a reaction of the epoxy group with diethylamine. Anion-exchange porous hollow-fiber membranes with a thickness of about 1.2 mm and a pore size of about 0.3 μm were used as a supporting matrix to immobilize cycloisomaltooligosaccharide glucanotransferase (CITase). CTTase was immobilized to the membrane via anion-exchange adsorption and by subsequent enzymatic cross-linking with transglutaminase, the amount of which ranged from 3 to 110 mg per g of the membrane. The degree of enzyme multilayer binding was equivalent to 0.3 to 9.8. Dextran, as the substrate, was converted into seven- to nine-glucose-membered cycloisomaltooligosaccharides (CI-7, -8 and -9) at a maximum yield of 28% in weight at a space velocity of 10 per hour during the permeation of 2.0 (w/w)% dextran solution across the CITase-immobilized porous hollow-fiber membrane. The yield of CIs increased with increasing degree of CITase multilayering. (author)

  19. Efficient drug delivery mechanisms of liposomes with tethered biopolymer brushes in aqueous solution using dissipative particle dynamics simulations

    CERN Document Server

    Goicochea, A Gama; Klapp, J; Pastorino, C

    2013-01-01

    We undertake the investigation of model liposomes covered with polyethylene glycol brushes as a case study for the mechanisms of efficient drug delivery in biologically relevant situations.Extensive non- equilibrium, coarse grained dissipative particle dynamics simulations of polymer brushes of various lengths and shear rates are performed, having in mind polymer brushes covering the surfaces of drug carrying liposomes in the human circulatory system.In particular, we calculate the viscosity and the friction coefficient for polymer brushes as functions of the shear rate and polymerization degree under theta solvent conditions, and find that the liposome brushes experience considerable shear thinning at large shear rates. The viscosity is shown to obey a scaling law at high shear rate irrespective of the brushes degree of polymerization. A new general scaling relation is obtained for the viscosity at high shear rates. These results reproduce very well trends in recent drug delivering experiments.

  20. Access to Interdental Brushing in Periodontal Healthy Young Adults: A Cross-Sectional Study

    Science.gov (United States)

    Santamaria, Julie; Bravo, Manuel; Bourgeois, Denis

    2016-01-01

    Purpose Interdental diameter space is largely undefined in adults, which compromises the decision support for daily interdental cleaning during routine practice in individual oral prophylaxis. This study assesses the distribution of diameter access of interdental spaces in an 18- to 25-year-old adult population free of periodontal disease. Methods In March-April 2015, a cross-sectional study using random sampling was performed at the University Lyon 1, France. The interproximal dental spaces of 99 individuals were examined using a colorimetric calibrated probe associated with the corresponding calibrated interdental brush (IDB). Results Of the 2,408 out of 2,608 sites, the overall accessibility prevalence of any interdental brushing was 92.3%. In total, 80.6% of the sites required interdental brushes with smaller diameters (0.6–0.7 mm). In anterior sites, the diameter of the interdental brushes used was smaller (55.8% of IDB with 0.6 mm) than the diameter of the interdental brushes used in posterior sites (26.1% of IDB with 0.6 mm) (p < 0.01). The adjusted ORs indicate a significant association with the location of the sites (approximately doubling the risk of bleeding, i.e., OR = 1.9, in posterior sites). Conclusions Most interdental sites can be cleaned using interdental brushes. Even in healthy people, interdental hygiene requirements are very high. Strengthening the oral hygiene capacity by specifically using interdental brushes can have an effect on the health of the entire population. Screening of the accessibility of the interdental space should be a component of a routine examination for all patients. PMID:27192409

  1. Quantitative evaluation of interaction force between functional groups in protein and polymer brush surfaces.

    Science.gov (United States)

    Sakata, Sho; Inoue, Yuuki; Ishihara, Kazuhiko

    2014-03-18

    To understand interactions between polymer surfaces and different functional groups in proteins, interaction forces were quantitatively evaluated by force-versus-distance curve measurements using atomic force microscopy with a functional-group-functionalized cantilever. Various polymer brush surfaces were systematically prepared by surface-initiated atom transfer radical polymerization as well-defined model surfaces to understand protein adsorption behavior. The polymer brush layers consisted of phosphorylcholine groups (zwitterionic/hydrophilic), trimethylammonium groups (cationic/hydrophilic), sulfonate groups (anionic/hydrophilic), hydroxyl groups (nonionic/hydrophilic), and n-butyl groups (nonionic/hydrophobic) in their side chains. The interaction forces between these polymer brush surfaces and different functional groups (carboxyl groups, amino groups, and methyl groups, which are typical functional groups existing in proteins) were quantitatively evaluated by force-versus-distance curve measurements using atomic force microscopy with a functional-group-functionalized cantilever. Furthermore, the amount of adsorbed protein on the polymer brush surfaces was quantified by surface plasmon resonance using albumin with a negative net charge and lysozyme with a positive net charge under physiological conditions. The amount of proteins adsorbed on the polymer brush surfaces corresponded to the interaction forces generated between the functional groups on the cantilever and the polymer brush surfaces. The weakest interaction force and least amount of protein adsorbed were observed in the case of the polymer brush surface with phosphorylcholine groups in the side chain. On the other hand, positive and negative surfaces generated strong forces against the oppositely charged functional groups. In addition, they showed significant adsorption with albumin and lysozyme, respectively. These results indicated that the interaction force at the functional group level might be

  2. Effect of toothbrushes and denture brushes on heat-polymerized acrylic resins.

    Science.gov (United States)

    de Freitas Pontes, Karina Matthes; de Holanda, Janaína Câncio; Fonteles, Cristiane Sa Roriz; Pontes, Cassio de Barros; Lovato da Silva, Cláudia Helena; Paranhos, Helena de Freitas Oliveira

    2016-01-01

    It is important to choose an appropriate brush for denture cleaning to prevent damage to the surface properties of prosthetic devices. The purpose of this study was to evaluate the abrasiveness of toothbrushes and denture brushes on boiled and microwave-processed acrylic resins. Specimens of 4 resin brands were prepared (n = 30). Five brands of brushes (n = 6) were used in a toothbrushing machine, first for 17,800 strokes and then for an additional 35,600 strokes (total of 53,400), at a load of 200 g. An analytical balance and a profilometer were used to assess the weight and surface roughness, respectively, before and after 17,800 and 53,400 strokes. Analysis of variance and Tukey tests were used for data analysis (α = 0.05). Weight loss increased with time, while surface roughness remained the same. There were no statistically significant differences among toothbrushes and denture brushes in the resulting weight loss (17,800 strokes, 1.83 mg; 53,400 strokes, 3.78 mg) or surface roughness (17,800 or 53,400 strokes, 0.14 µm). The weight loss values after 53,400 brush strokes indicated that Clássico (2.28 mg) and VIPI Wave (2.75 mg) presented significantly greater abrasion resistance than Lucitone 550 (3.36 mg) and Onda-Cryl (2.85 mg) (P < 0.05). The type of brush and the polymerization method did not influence resin wear after brushing. PMID:26742168

  3. Wear property of high-resistivity carbon brushes made with and without MoS2 in variable humidity

    Institute of Scientific and Technical Information of China (English)

    HU Zhong-liang; CHEN Zhen-hua; XIA Jin-tong; DING Guo-yun

    2008-01-01

    Four kinds of high-resistivity carbon brushes with MoS2 contents of 0%, 2%, 4% and 6% (mass fraction) were prepared, respectively. Wear tests of brushes were conducted on an alternate current(AC) motor. Scanning electron microscopy(SEM) and energy dispersive X-ray analysis(EDS) were used to analyze the worn surface of brushes, and a thermocouple was used to measure the bulk temperature of the brush. The results show that wear rate of brush made without MoS2 in 10% relative humidity(RH) is two times larger than that in 50% RH, whereas the wear rates change little for the brushes made with MoS2. The wear of brushes has much to do with the surface film. In low humidity, the surface film can not be formed for the former brush while a sulfur layer can be formed for the latter brushes,which can reduce sparks, frictional heat and wear rate, and play a role like the water film in high humidity.

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

    KAUST Repository

    Lanas, Vanessa

    2014-02-01

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

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

    Directory of Open Access Journals (Sweden)

    Anton Rahardjo

    2015-05-01

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

  6. Electric motors for robotics; Moteurs electriques pour la robotique

    Energy Technology Data Exchange (ETDEWEB)

    Maye, P.

    2000-07-01

    This book presents the technology of DC motors, DC brush-less motors and step by step motors as used in robotics. It describes also the speed and positioning servo-systems with their electronic circuits, the overheating problems and the selection criteria for a given electric motor. (J.S.)

  7. Amiloride transport in rabbit renal brush-border membrane vesicles

    International Nuclear Information System (INIS)

    Rabbit renal brush-border membrane vesicles (BBMV) were used to study amiloride transport across the luminal membrane of proximal tubular cells. An outwardly directed H+ gradient (pHi 6.0; pHo 7.5) stimulated 8 microM [14C]-amiloride uptake into BBMV and supported a transient active accumulation of substrate consistent with the presence of an amiloride-H+ exchange process. Uptake was inhibited, in the presence or absence of a pH gradient, by 1 mM unlabeled amiloride or 20 mM tetraethylammonium (TEA). Amiloride transport was not directly affected by the presence of 100 mM Na+ in the extravesicular medium, suggesting that Na-H exchange did not mediate amiloride flux. Amiloride transport was a saturable process with a maximal flux (under pH gradient conditions) of 3 nmol.mg-1.min-1 and an apparent Kt of 8 microM. TEA acted as a competitive inhibitor of this process with an apparent Ki of approximately 80 microM, similar to the Kt of TEA transport via the TEA-H+ exchanger. Likewise, amiloride acted as a competitive inhibitor of TEA uptake with an apparent Ki of approximately 11 microM. Preloading BBMV with 1-2 mM TEA stimulated the rate of amiloride uptake and supported a transient active accumulation of amiloride. We conclude that amiloride and TEA are transported by a common pathway in BBMV, which involves a carrier-mediated exchange with H+ and which may play a role in the tubular secretion of these compounds

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-11-30

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

  9. Role of brush cytology in the diagnosis of Barrett's esophagus: an analysis of eight cases.

    Science.gov (United States)

    Padmavathy, Femila; Siddaraju, Neelaiah; Sistla, Sarath Chandra

    2011-01-01

    Although debatable, role of cytology in diagnosing Barrett's esophagus has been stressed by some authors. Our brief report analyses the role of brush cytology (BC) in its diagnosis. Eight patients who presented with upper gastrointestinal (GI) manifestations and subsequently diagnosed to have Barrett's esophagus with or without adenocarcinoma on brush cytology (BC) or, endoscopic biopsy (EB) or, a combination of both the techniques were included in the study. In all the cases routine cytologic smears and histologic sections with relevant special stains (when essential) were studied. On cytology, the diagnosis of "Barrett's esophagus" was made when the esophageal brushings obtained from a region beyond 3 cm from the gastroesophageal junction showed closely intermingled clusters of squamous and columnar cells, or when there was evidence of intestinal metaplasia. Adenocarcinoma in Barrett's esophagus was diagnosed by the usual criteria for malignancy with features of adenocarcinoma. Cytologic diagnoses were correlated with the histologic diagnoses. Of the eight cases, seven had histopathologic correlation of which six had evidence of BE on BC; four had cytohistologic concordance, of which three cases revealed adenocarcinoma arising in BE. Two endoscopic biopsies were nonrepresentative. In one case, cytology missed Barrett's esophagus. For two cases in which cytology detected Barrett's mucosa, biopsies were nonrepresentative. Our study showed brush cytology (BC) to be a fairly reliable test for detecting Barrett's esophagus. Owing to its inherent advantage of sampling a wider and circumferential area, a technically well performed brushing procedure is likely to be more representative and superior than multiple endoscopic biopsies. PMID:21162095

  10. Profilometric analysis of two composite resins′ surface repolished after tooth brush abrasion with three polishing systems

    Directory of Open Access Journals (Sweden)

    Mudit Uppal

    2013-01-01

    Full Text Available Aim: To evaluate the effect of three polishing protocols that could be implemented at recall on the surface roughness of two direct esthetic restorative materials. Materials and Methods: Specimens (n = 40 measuring 8 mm (length × 5 mm (width × 4 mm (height were fabricated in an acrylic mold using two light-cured resin-based materials (microfilled composite and microhybrid composite. After photopolymerization, all specimens were finished and polished with one of three polishing protocols (Enhance, One Gloss, and Sof-Lex polishing systems. The average surface roughness of each treated specimen was determined using 3D optical profilometer. Next all specimens were brushed 60,000 times with nylon bristles at 7200 rpm using crosshead brushing device with equal parts of toothpaste and water used as abrasive medium. The surface roughness of each specimen was measured after brushing followed by repolishing with one of three polishing protocols, and then, the final surface roughness values were determined. Results: The data were analyzed using one-way and two-factor analysis of variance (ANOVA and Tukey′s honestly significant difference (HSD. Significant difference (P < 0.05 in surface roughness was observed. Simulated brushing following initial polishing procedure significantly roughened the surface of restorative material (P < 0.05. Conclusion: Polishing protocols can be used to restore a smooth surface on esthetic restorative materials following simulated tooth brushing.

  11. Glassy dynamics of poly(2-vinyl-pyridine) brushes with varying grafting density.

    Science.gov (United States)

    Neubauer, Nils; Winkler, René; Tress, Martin; Uhlmann, Petra; Reiche, Martin; Kipnusu, Wycliffe Kiprop; Kremer, Friedrich

    2015-04-21

    The molecular dynamics of poly(2-vinyl-pyridine) (P2VP) brushes is measured by Broadband Dielectric Spectroscopy (BDS) in a wide temperature (250 K to 440 K) and broad spectral (0.1 Hz to 1 MHz) range. This is realized using nanostructured, highly conductive silicon electrodes being separated by silica spacers as small as 35 nm. A "grafting-to"-method is applied to prepare the P2VP-brushes with five different grafting densities (0.030 nm(-2) to 0.117 nm(-2)), covering the "true-brush" regime with highly stretched coils and the "mushroom-to-brush" transition regime. The film thickness ranges between 1.8 to 7.1 (±0.2) nm. Two relaxations are observed, an Arrhenius-like process being attributed to fluctuations in the poly(glycidyl-methacrylate) (PGMA) linker used for the grafting reaction and the segmental dynamics (dynamic glass transition) of the P2VP brushes. The latter is characterized by a Vogel-Fulcher-Tammann dependence similar to bulk P2VP. The results can be comprehended considering the length scale on which the dynamic glass transition (≤1 nm) takes place. PMID:25740018

  12. Structure of bottle brush polymers on surfaces: weak versus strong adsorption.

    Science.gov (United States)

    Hsu, Hsiao-Ping; Paul, Wolfgang; Binder, Kurt

    2011-12-01

    Large-scale Monte Carlo simulations are presented for a coarse-grained model of cylindrical molecular brushes adsorbed on a flat structureless substrate, varying both the chain length N of the side chains and the backbone chain length N(b). For the case of good solvent conditions, both the cases of weak adsorption (only 10 to 15% of the monomers being bound to the surface) and strong adsorption (~40% of the monomers being bound to the surface, forcing the bottle brush into an almost 2D conformation) are studied. We focus on the scaling of the total linear dimensions of the cylindrical brush with both chain lengths N and N(b), demonstrating a crossover from rod-like behavior (for not very large N(b)) to the scaling of 2D self-avoiding walks. Despite the fact that snapshot pictures suggest a "worm-like" picture as a coarse-grained description of such cylindrical brushes, the Kratky-Porod worm-like chain model fails because there is no regime where Gaussian statistics applies. We compare the stiffness (orientational correlations of backbone bonds, persistence length estimates, etc.) of the adsorbed bottle brush polymers with their corresponding 3D nonadsorbed counterparts. Consequences for the discussion of pertinent experiments are briefly discussed. PMID:21751800

  13. Brushes of semiflexible polymers in equilibrium and under flow in super-hydrophobic regime

    CERN Document Server

    Speyer, Kevin

    2015-01-01

    We performed molecular dynamics simulations to study equilibrium and flow properties of a liquid in a nano-channel with confining surfaces coated with a layer of grafted semiflexible polymers. The coverage spans a wide range of grafting densities from essentially isolated chains to dense brushes. The end-grafted polymers were described by a bead spring model with an harmonic potential to include the bond stiffness of the chains. We varied the rigidity of the chains, from fully flexible polymers to rigid rods, in which the configurational entropy of the chains is negligible. The brush-liquid interaction was tuned to obtain a super-hydrophobic channel, in which the liquid did not penetrate the polymer brush, giving rise to a Cassie-Baxter state. Equilibrium properties such us brush height and bending energy were measured, varying the grafting density and the stiffness of the polymers. We studied also the characteristics of the brush-liquid interface and the morphology of the polymers chains supporting the liqui...

  14. Particles Bridge the Gap -- Relevance of Polymer Graft Architecture on the Properties of Particle Brush Assemblies

    Science.gov (United States)

    Bockstaller, Michael

    2011-03-01

    Current interest in the assembly of ligand-coated nanoparticles into 2D and 3D array structures is driven by the opportunities for novel material technologies that derive from the interactions within nanoparticle superlattice structures. A common challenge in the solution-based assembly of particle superlattice structures is the propensity of hard-sphere type particle assemblies to crack formation and brittle fracture during solvent evaporation. Recent progress in controlled radical polymerization offers novel opportunities for polymer-stabilized particle systems (particle brushes) as building blocks of particle superlattice structures. This contribution will discuss synthetic strategies to realize particle brush systems with well defined polymer graft-architecture in the dense or semi-dilute brush regime and discuss the effect of polymer grafting on the structure formation and cohesive interactions in particle brush assemblies. In particular, it will be demonstrated chain entanglements between surface-grafted chains give rise to fracture through polymer-like crazing thus dramatically increasing the toughness and flexibility of the particle assembly. The modulus and toughness of polymer nanocomposites synthesized by self-assembly of particle brush systems will be shown to exceed those of ``conventional'' particle-filled polymer composites -- a result that will be interpreted as a consequence of the particular conformational constraints of surface grafted chains. The author acknowledges financial support by AFOSR and DTRA.

  15. Novel graphene papers with sporadic alkyl brushes on the basal plane as a high-capacity flexible anode for lithium ion batteries

    International Nuclear Information System (INIS)

    Graphene paper that exhibits an excellent stabilized capacity, as high as 1300 mAh g−1 at a current rate of 60 mA g−1, as a lithium ion battery anode is fabricated and evaluated. The few-layer graphene used to make the graphene paper is prepared via the thermal reduction of graphite oxide. The graphene is then modified by a novel method utilizing inherent defects, namely epoxy groups, on the graphene as active sites for a reaction with methanol, 1-butanol, 1-hexanol, and 1-octanol. The density values and X-ray diffraction patterns obtained for the graphene paper demonstrate that the alkyl brushes on the graphene sheets expand the d-spacing and hinder close restacking of the sheets, thereby inducing the formation of extra cavities within the paper. This loose packing due to the alkyl brushes increases sensitively as the alkyl chain length of the alcohol becomes longer. The lithium ion insertion capacity of a graphene paper electrode at the first cycle also increases with the alkyl chain length. However, fading of the capacity at early charge/discharge cycles is accelerated by the modification process because of electrolyte penetration into the gallery and the acceleration of protective solid electrolyte interface film formation due to looser packing. The paper composed of graphene modified with 1-butanol rather than shorter or longer alcohols exhibits the best reversible storage capacity, more than two-fold higher when compared to that of pristine graphene paper, due to a compromise between two conflicting effects on the reversible storage capacity by long alkyl brushes. The tensile properties and electrical conductivity of the graphene papers are also examined

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

    DEFF Research Database (Denmark)

    Danielsen, E M

    1995-01-01

    A number of transmembrane digestive enzymes of the porcine small intestinal brush border membrane were found to be partially Triton X-100-insoluble at 0 degree C and colocalized in gradient centrifugation experiments with the GPI-anchored alkaline phosphatase in low-density, detergent......%), and lactase-phlorizin hydrolase (EC 3.2.1.23-62) was essentially fully soluble in detergent. In radioactively labeled, mucosal explants, the newly synthesized brush border enzymes began to associate with detergent-insoluble complexes while still in their transient, high mannose-glycosylated form, and...... their insolubility increased to that of the steady-state level soon after they achieved their mature, complex glycosylation, i.e., after passage through the Golgi complex. Detergent-insoluble complexes isolated by density gradient centrifugation were highly enriched in brush border enzymes, and the...

  17. Streaming Potential and Energy Conversion in Nanochannel Grafted With Poly-Zwitterion Brushes

    Science.gov (United States)

    Patwary, Jahin; Chen, Guang; Das, Siddhartha

    2015-11-01

    Here we study the streaming potential and electrochemomechanical energy conversion in nanochannels grafted with poly-zwitterion (PZ) brushes. PZs are polymer molecules consisting of negative and positive charge centres simultaneously; depending on the bulk pH, the extent of dissociation differs at each of these charge centres, yielding a particular net charge on the PZ molecule. This PZ charge, therefore, develops a pH dependent electrostatics of the PZ brushes grafted at the naochannel walls. We develop a self-consistent field theory model to calculate this electrostatics by appropriately accounting for the explicit hydrogen ion concentration. Secondly, we use this electrostatics to calculate the streaming potential and the resulting electrochemomechanical energy conversion in nanochannels grafted with poly-zwitterion (PZ) brushes. Our results indicate distinct influences of pH, bulk ion concentration, and the ionization parameters of the PZs in regulating the nanochannel energy conversion. Bridge to the Doctorate Fellowship - LSAMP Committee.

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

    Directory of Open Access Journals (Sweden)

    Matsuoka Hideki

    2013-08-01

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

  19. Core-shell-corona-structured polyelectrolyte brushes-grafting magnetic nanoparticles for water harvesting.

    Science.gov (United States)

    Liu, Guoqiang; Cai, Meirong; Wang, Xiaolong; Zhou, Feng; Liu, Weimin

    2014-07-23

    A novel superhydrophilic material, charged polymer brushes-grafted magnetic core-shell-corona composite nanoparticles (Fe3O4@SiO2@PSPMA), was developed to harvest water through the hydration effect. Because of both the strong hydration capability and the good swelling performance, the negatively charged polymer brushes, PSPMA brushes, endow the composite nanoparticles with superhydrophilicity and a good water-absorbing performance like a sponge, while the magnetic Fe3O4 cores allow easy separation of Fe3O4@SiO2@PSPMA nanoparticles with absorbed water from oil/water mixture under an external magnetic field. The functional particles have the capability of harvesting water droplets whether floating on an oil surface or in the oil. This water-absorbing material uses selective wettability to harvest water and achieve oil-water separation and may be useful in finding novel approaches for recycling water from sewage and removing water in the petroleum industry. PMID:24955817

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

    DEFF Research Database (Denmark)

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

    2011-01-01

    Free fatty acids released during intralumenal digestion of dietary fat must pass through the enterocyte brush border membrane before triacylglycerol reassembly and subsequent chylomicron delivery to the lymph system. In the present work fluorescent BODIPY fatty acid analogs were used to study this......-linked enzyme is the membrane protein in the brush border with the highest affinity for lipid rafts, this implies that free fatty acids selectively insert stably into these membrane microdomains. We have previously shown that absorption of dietary lipids transiently induce a selective endocytosis of AP from the...... brush border, and from work by others it is known that fat absorption is accompanied by a rise in serum AP and secretion of surfactant-like particles from enterocytes. We propose that these physiological processes may be triggered by the sequestering of dietary free fatty acids in lipid raft...

  1. A brush-shaped air plasma jet operated in glow discharge mode at atmospheric pressure

    Science.gov (United States)

    Li, Xuechen; Bao, Wenting; Jia, Pengying; Di, Cong

    2014-07-01

    Using ambient air as working gas, a direct-current plasma jet is developed to generate a brush-shaped plasma plume with fairly large volume. Although a direct-current power supply is used, the discharge shows a pulsed characteristic. Based on the voltage-current curve and fast photography, the brush-shaped plume, like the gliding arc plasma, is in fact a temporal superposition of a moving discharge filament in an arched shape. During it moves away from the nozzle, the discharge evolves from a low-current arc into a normal glow in one discharge cycle. The emission profile is explained qualitatively based on the dynamics of the plasma brush.

  2. Highly efficient antibacterial surface grafted with a triclosan-decorated poly(N-hydroxyethylacrylamide) brush.

    Science.gov (United States)

    Wu, Hai-Xia; Tan, Lei; Tang, Zhao-Wen; Yang, Mei-Yan; Xiao, Jian-Yun; Liu, Chuan-Jun; Zhuo, Ren-Xi

    2015-04-01

    This work presented a highly efficient antibacterial Ti-surface which was grafted with poly(N-hydroxyethylacrylamide) (PHEAA) brush and further decorated with triclosan (TCS). The modified surfaces were characterized using contact angle measurements, X-ray photoelectron spectroscopy, and attenuated total reflectance Fourier transform infrared. The antibacterial performance of the modified surfaces was evaluated using the Streptococcus mutans and Actinomyces naeslundii attachment test. The Ti surface with PHEAA brush (Ti-PHEAA) was able to resist the adhesion of the bacteria, while the TCS-decorated Ti surface (Ti-TCS) showed the capability of killing the bacteria adhered on the surface. As we coupled the TCS to the PHEAA brush, the surface showed highly efficient antibacterial performance due to the combination of the resistance to the bacteria adhesion and its activity of killing bacteria. PMID:25756367

  3. A 30 mm Wide DC-Driven Brush-Shaped Cold Air Plasma Without Airflow Supplement

    International Nuclear Information System (INIS)

    This paper reports a cold atmospheric pressure DC-driven air plasma brush. Three stainless steel needles are symmetrically mounted on a slot shaped PVC slab to act as the electrodes. The brush driven by a direct current (DC) power supply can generate an air plasma glow up to 30 mm wide with no inert gas addition and no air flow supplement. The plasma glow appears uniform no matter what kinds of material are processed. The measured current and the simulated current all show that each pulsed discharge including two peaks always occurs for different gaps between electrodes. Emission spectra measurement result shows that the obtained rotational temperatures are 300 K and the vibrational temperatures are 2250 K. Some reactive species are presented in the plasma glow, which suggest that the proposed plasma brush is beneficial to practical applications. (low temperature plasma)

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

    International Nuclear Information System (INIS)

    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 into 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 Ca2+-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 [32P]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

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

    Energy Technology Data Exchange (ETDEWEB)

    Donowitz, M.; Emmer, E.; McCullen, J.; Reinlib, L.; Cohen, M.E.; Rood, R.P.; Madara, J.; Sharp, G.W.G.; Murer, H.; Malmstrom, K.

    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 into 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.

  6. Molecular model of the microvillar cytoskeleton and organization of the brush border.

    Directory of Open Access Journals (Sweden)

    Jeffrey W Brown

    Full Text Available BACKGROUND: Brush border microvilli are approximately 1-microm long finger-like projections emanating from the apical surfaces of certain, specialized absorptive epithelial cells. A highly symmetric hexagonal array of thousands of these uniformly sized structures form the brush border, which in addition to aiding in nutrient absorption also defends the large surface area against pathogens. Here, we present a molecular model of the protein cytoskeleton responsible for this dramatic cellular morphology. METHODOLOGY/PRINCIPAL FINDINGS: The model is constructed from published crystallographic and microscopic structures reported by several groups over the last 30+ years. Our efforts resulted in a single, unique, self-consistent arrangement of actin, fimbrin, villin, brush border myosin (Myo1A, calmodulin, and brush border spectrin. The central actin core bundle that supports the microvillus is nearly saturated with fimbrin and villin cross-linkers and has a density similar to that found in protein crystals. The proposed model accounts for all major proteinaceous components, reproduces the experimentally determined stoichiometry, and is consistent with the size and morphology of the biological brush border membrane. CONCLUSIONS/SIGNIFICANCE: The model presented here will serve as a structural framework to explain many of the dynamic cellular processes occurring over several time scales, such as protein diffusion, association, and turnover, lipid raft sorting, membrane deformation, cytoskeletal-membrane interactions, and even effacement of the brush border by invading pathogens. In addition, this model provides a structural basis for evaluating the equilibrium processes that result in the uniform size and structure of the highly dynamic microvilli.

  7. Examining Scientific and Technical Writing Strategies in the 11th Century Chinese Science Book "Brush Talks from Dream Brook"

    Science.gov (United States)

    Zhang, Yuejiao

    2013-01-01

    This article examines the influential Chinese science book "Brush Talks from Dream Brook," written by Shen Kuo in the 11th century. I suggest that "Brush Talks" reveals a tension between institutionalized science and science in the public, and a gap between the making of scientific knowledge and the communication of such…

  8. Development and Implementation of Brush less DC Motor Controllers Based on Intelligent Control

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jin Hyun [Pusan Junior College, Pusan (Korea, Republic of); Choi, Young Kiu [Pusan National University, Pusan (Korea, Republic of)

    1997-06-01

    This paper proposes an intelligent controller for brush less DC motor and load with unknown nonlinear dynamics. The proposed intelligent control system consists of a plant identifier and PID controller with varying gains. The identifier is constructed using an Auto Regressive Moving Average(ARMA) model. In order to tune the parameters of the identifier and the gains of the PID controller efficiently, we also propose a modified Evolution Strategy. Experimental results show that the proposed intelligent controller for brush less DC motor has good control performance under unknown disturbance. (author). 13 refs., 7 figs., 1 tab.

  9. Bottle-brush polymers as an intermediate between star and cylindrical polymers

    Science.gov (United States)

    Denesyuk, N. A.

    2003-09-01

    We present a theoretical study of a single bottle-brush molecule, which consists of multiarmed polymer stars grafted densely onto a stiff backbone. Mean-field approximation and a variational approach are used to calculate the dominant trajectories of the grafted chains, the shape of the molecule, and the segment density distribution around the backbone. All these properties are calculated for an arbitrary relationship between the size of the backbone and that of a grafted star. Hence cylindrical comb copolymer brushes and spherically symmetric polymer stars are considered as the limiting cases of the present problem.

  10. Bottle-brush polymers as an intermediate between star and cylindrical polymers.

    Science.gov (United States)

    Denesyuk, N A

    2003-09-01

    We present a theoretical study of a single bottle-brush molecule, which consists of multiarmed polymer stars grafted densely onto a stiff backbone. Mean-field approximation and a variational approach are used to calculate the dominant trajectories of the grafted chains, the shape of the molecule, and the segment density distribution around the backbone. All these properties are calculated for an arbitrary relationship between the size of the backbone and that of a grafted star. Hence cylindrical comb copolymer brushes and spherically symmetric polymer stars are considered as the limiting cases of the present problem. PMID:14524794

  11. A corrosion resistant cerium oxide based coating on aluminum alloy 2024 prepared by brush plating

    International Nuclear Information System (INIS)

    Cerium oxide based coatings were prepared on AA2024 Al alloy by brush plating. The characteristic of this technology is that hydrogen peroxide, which usually causes the plating solution to be unstable, is not necessary in the plating electrolyte. The coating showed laminated structures and good adhesive strength with the substrate. X-ray diffraction and X-ray photoelectron spectroscopy analysis showed that the coatings were composed of Ce(III) and Ce(IV) oxides. The brush plated coatings on Al alloys improved corrosion resistance. The influence of plating parameters on structure and corrosion resistance of the cerium oxide based coating was studied.

  12. Electrophysiological, morphological and topological properties of two histochemically distinct subpopulations of cerebellar unipolar brush cells

    OpenAIRE

    Kim, Jin-Ah; Sekerková, Gabriella; Mugnaini, Enrico; Martina, Marco

    2012-01-01

    Unipolar brush cells (UBCs) are excitatory cerebellar granular layer interneurons whose brush-like dendrites receive one-to-one mossy fiber inputs. Subclasses of UBCs differ primarily by expressing metabotropic glutamate receptor (mGluR) 1α or calretinin. We used GENSAT Tg(Grp-EGFP) BAC-transgenic mice, which selectively express EGFP in mGluR1α-positive UBCs to compare the functional properties of the two subclasses. Compared to EGFP-negative UBCs, which include the calretinin-positive cells,...

  13. A corrosion resistant cerium oxide based coating on aluminum alloy 2024 prepared by brush plating

    Energy Technology Data Exchange (ETDEWEB)

    Tang Junlei; Han Zhongzhi [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Zuo Yu, E-mail: zuoy@mail.buct.edu.cn [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Tang Yuming [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)

    2011-01-15

    Cerium oxide based coatings were prepared on AA2024 Al alloy by brush plating. The characteristic of this technology is that hydrogen peroxide, which usually causes the plating solution to be unstable, is not necessary in the plating electrolyte. The coating showed laminated structures and good adhesive strength with the substrate. X-ray diffraction and X-ray photoelectron spectroscopy analysis showed that the coatings were composed of Ce(III) and Ce(IV) oxides. The brush plated coatings on Al alloys improved corrosion resistance. The influence of plating parameters on structure and corrosion resistance of the cerium oxide based coating was studied.

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-04-21

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

  16. Preparation and characterization of macromolecular “hedge” brushes grafted from Au nanowires

    NARCIS (Netherlands)

    Zapotoczny, Szczepan; Benetti, Edmondo M.; Vancso, G. Julius

    2007-01-01

    Linear polymer brush structures of poly(methacrylic acid) chains, exhibiting a width from several hundred to 20–30 nm and a controllable height (nano-“hedge”), were grafted from designer substrates by photopolymerization using thiol-based iniferters assembled on Au nano-lines. The Au nano-lines were

  17. Magnetite/Polymer Brush Nanocomposites with Switchable Uptake Behavior Toward Methylene Blue.

    Science.gov (United States)

    Dolatkhah, Asghar; Wilson, Lee D

    2016-03-01

    The grafting from approach was used to prepare pH-responsive polyacid brushes using poly(itaconic acid) (PIA) and poly(acrylic acid) (PAA) at the amine functional groups of chitosan. Hybrid materials consisting of polymer brushes and magnetite nanoparticles (MNPs) were also prepared. The products were structurally characterized and displayed reversible pH-responsive behavior and controlled adsorption/desorption of methylene blue (MB). Switchable binding of MB involves cooperative effects due to conformational changes of brushes and swelling phenomena in solution which arise from response to changes in pH. Above the pKa, magnetic nanocomposites (MNCs) are deprotonated and display enhanced electrostatic interactions with high MB removal efficiency (>99%). Below the pKa, MNCs undergo self-assembly and release the cationic dye. The switchable binding of MB and the structure of the polymer brush between collapsed and extended forms relate to changes in osmotic pressure due to reversible ionization of acid groups at variable pH. Reversible adsorption-desorption with variable binding affinity and regeneration ability was demonstrated after five cycles. PMID:26751742

  18. A novel shortened electrospun nanofiber modified with a 'concentrated' polymer brush

    International Nuclear Information System (INIS)

    We report the fabrication of shortened electrospun polymer fibers with a well-defined concentrated polymer brush. We first prepared electrospun nanofibers from a random copolymer of styrene and 4-vinylbenzyl 2-bromopropionate, with number-average molecular weight Mn=105 200 and weight-average molecular weight Mw=296 700 (Mw/Mn=2.82). The fibers had a diameter of 593±74 nm and contained initiating sites for surface-initiated atom transfer radical polymerization (SI-ATRP). Then, SI-ATRP of hydrophilic styrene sodium sulfonate (SSNa) was carried out in the presence of a free initiator and the hydrophobic fibers. Gel permeation chromatography confirmed that Mn and Mw/Mn values were almost the same for free polymers and graft polymers. Mn agreed well with the theoretical prediction, and Mw/Mn was relatively low (n, we calculated the graft density σ as 0.22 chains nm-2. This value was nearly equal to the density obtained on silicon wafers (σ=0.24 chains nm-2), which is categorized into the concentrated brush regime. Finally, we mechanically cut the fibers with a concentrated poly(SSNa) brush by a homogenizer. With increasing cutting time, the fiber length became shorter and more homogenous (11±17 μm after 3 h). The shortened fibers exhibited excellent water dispersibility owing to the hydrophilic poly(SSNa) brush layer.

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

    International Nuclear Information System (INIS)

    A brush border preparation from rat intestine was incubated with rat intrinsic factor-vitamin B12 complex in 0.01M Tris-HCl buffer, pH 7.4. The 57Co-B12 uptake to brush borders was proportional to the amount of protein or to alkaline phosphatase activity in the preparations. The uptake increased with time of incubation. At 370C, the uptake after incubation for 15 min. was 80-85% of that for one hr. The uptake at 4 0C was approximately 70% of that at 37 0C. There was no difference as a result of adding glucose to the incubation medium. The uptake was observed in the alkaline environment above pH 6.3. Maximum uptake occurred at pH 8.0. Brush borders washed with Krebs-Ringer bicarbonate buffer (pH 7.4) exhibited no difference in B12 uptake, whether in the presence of absence of calcium ion. But brush borders washed with ethylenediaminetetraacetate exhibited no uptake when incubated in calcium-free medium. The uptake reached a maximum by addition of calcium ion at a concentration of 0.3 mM, and was not alter up to 10 mM. Addition of magnesium ion exhibited no uptake. Calcium-dependent B12 uptake was markedly inhibited by manganese ion. Magnesium ion seemed to slightly inhibit the calcium-dependent uptake. (auth.)

  20. Aluminum hydroxide coating thickness measurements and brushing tests on K West Basin fuel elements

    International Nuclear Information System (INIS)

    Aluminum hydroxide coating thicknesses were measured on fuel elements stored in aluminum canisters in K West Basin using specially developed eddy current probes . The results were used to estimate coating inventories for MCO fuel,loading. Brushing tests successfully demonstrated the ability to remove the coating if deemed necessary prior to MCO loading

  1. RAFT vs. ATRP polymerization of N-(Tris(hydroxymethyl)methyl)-acrylamide for new nonfouling polymer brushes

    Czech Academy of Sciences Publication Activity Database

    Surman, František; Rodriguez-Emmenegger, Cesar; de los Santos Pereira, Andres; Šubr, Vladimír; Houska, Milan; Kaňková, Dana; Sedláková, Zdeňka

    Pisa : European Polymer Federation, 2013. O3-84. [European Polymer Congress - EPF 2013. 16.06.2013-21.06.2013, Pisa] R&D Projects: GA ČR GAP106/12/1451; GA ČR GAP205/12/1702 Institutional support: RVO:61389013 Keywords : non-fouling polymer brushe * RAFT polymerization Subject RIV: CD - Macromolecular Chemistry

  2. The efficacy of interdental brushes on plaque and parameters of periodontal inflammation: a systematic review

    NARCIS (Netherlands)

    D.E. Slot; C.E. Dörfer; G.A. van der Weijden

    2008-01-01

    Aim: The aim of the study was to asses the effect of the use of interdental brushes (IDB) in patients as an adjunct to toothbrushing compared with toothbrushing alone or other interdental oral hygiene devices on plaque and the clinical parameters of periodontal inflammation. Material and methods: ME

  3. New Development of Monte Carlo Techniques for Studying Bottle-brush Polymers

    Science.gov (United States)

    Hsu, Hsiao-Ping

    Due to the complex characteristics of bottle-brush polymers, it became a challenge to develop an e_cient algorithm for studying such macromolecules under various solvent conditions or some constraints in the space by using computer simulations. In the limit of a bottle-brush polymer with a rather sti_ backbone (straight rigid backbone), we generalize the variant of the biased chain growth algorithm, the pruned-enriched Rosenbluth method, for simulating polymers with complex architecture, from star polymers to bottle-brush polymers, on the simple cubic lattice. With the high statistics of our Monte Carlo results, we check the theoretical predictions of side chain behavior and radial monomer density profile. For the comparison of the experimental data for bottle-brush polymers with a flexible backbone and flexible side chains, based on the bond fluctuation model we propose another fast Monte Carlo algorithm combining the local moves, the pivot move, and an adjustable simulation lattice box. By monitoring the autocorrelation functions of gyration radii for the side chains and for the backbone, we see that for fixed side chain length there is no change in the behavior of these two functions as the backbone length increases. Our extensive results cover the range which is accessible for the comparison to experimental data and for the checking of the theoretically predicted scaling laws.

  4. Controlled growth of protein resistant PHEMA brushes via S-RAFT polymerization

    Czech Academy of Sciences Publication Activity Database

    Zamfir, M.; Rodriguez-Emmenegger, Cesar; Bauer, S.; Barner, L.; Rosenhahn, A.; Barner-Kowollik, C.

    2013-01-01

    Roč. 1, č. 44 (2013), s. 6027-6034. ISSN 2050-750X R&D Projects: GA ČR GAP205/12/1702; GA ČR GAP106/12/1451 Institutional support: RVO:61389013 Keywords : surface RAFT * polymer brushes * antifouling Subject RIV: CD - Macromolecular Chemistry

  5. Brush border myosin Ia inactivation in gastric but not endometrial tumors

    NARCIS (Netherlands)

    Mazzolini, Rocco; Rodrigues, Paulo; Bazzocco, Sarah; Dopeso, Higinio; Ferreira, Ana M.; Mateo-Lozano, Silvia; Andretta, Elena; Woerner, Stefan M.; Alazzouzi, Hafid; Landolfi, Stefania; Hernandez-Losa, Javier; Macaya, Irati; Suzuki, Hiromu; Ramon y Cajal, Santiago; Mooseker, Mark S.; Mariadason, John M.; Gebert, Johannes; Hofstra, Robert M. W.; Reventos, Jaume; Yamamoto, Hiroyuki; Schwartz, Simo; Arango, Diego

    2013-01-01

    Brush border Myosin Ia (MYO1A) has been shown to be frequently mutated in colorectal tumors with microsatellite instability (MSI) and to have tumor suppressor activity in intestinal tumors. Here, we investigated the frequency of frameshift mutations in the A8 microsatellite in exon 28 of MYO1A in MS

  6. Organic thin film transistors with polymer brush gate dielectrics synthesized by atom transfer radical polymerization

    DEFF Research Database (Denmark)

    Pinto, J.C.; Whiting, G.L.; Khodabakhsh, S.;

    2008-01-01

    Low operating voltage is an important requirement that must be met for industrial adoption of organic field-effect transistors (OFETs). We report here solution fabricated polymer brush gate insulators with good uniformity, low surface roughness and high capacitance. These ultra thin polymer films...

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

    DEFF Research Database (Denmark)

    Danielsen, E M; Hansen, Gert Helge

    2008-01-01

    The enterocyte brush border of the small intestine is a highly specialized membrane designed to function both as a high capacity digestive/absorptive surface of dietary nutrients and a permeability barrier towards lumenal pathogens. It is characterized by an unusually high content of glycolipids...

  8. Brush seal leakage performance with gaseous working fluids at static and low rotor speed conditions

    Science.gov (United States)

    Carlile, Julie A.; Hendricks, Robert C.; Yoder, Dennis A.

    1992-01-01

    The leakage performance of a brush seal with gaseous working fluids at static and low rotor speed conditions was studied. The leakage results included for air, helium, and carbon dioxide at several bristle/rotor interferences. Also, the effects of packing a lubricant into the bristles and also of reversing the pressure drop across the seal were studied. Results were compared to that of an annular seal at similar operating conditions. In order to generalize the results, they were correlated using corresponding state theory. The brush seal tested had a bore diameter of 3.792 cm (1.4930 in.), a fence height of 0.0635 cm (0.025 in.), and 1800 bristles/cm circumference (4500 bristles/in. circumference). Various bristle/rotor radial interferences were achieved by using a tapered rotor. The brush seal reduced the leakage in comparison to the annular seal, up to 9.5 times. Reversing the pressure drop across the brush seal produced leakage rates approximately the same as that of the annular seal. Addition of a lubricant reduced the leakage by 2.5 times. The air and carbon dioxide data were successfully correlated using corresponding state theory. However, the helium data followed a different curve than the air and carbon dioxide data.

  9. Clinical evaluation of an ionic tooth brush on oral hygiene status, gingival status, and microbial parameter

    Directory of Open Access Journals (Sweden)

    Deshmukh J

    2006-01-01

    Full Text Available It has long been recognised that the presence of dental plaque leads to gingivitis and periodontal disease, as well as dental caries. Today tooth brushing is the most widely accepted method of removing plaque. Hence this present clinical study was undertaken to evaluate the effectiveness of an ionic toothbrush on oral hygiene status. For this study, 20 dental students in the age group of 18-20 years were included. All the subjects after undergoing dental prophylaxis were then provided with ionic toothbrushes, either active (equipped with lithium battery or inactive (without lithium battery. Plaque index and gingival bleeding index were examined at 7th, 14th, and 21st day. Microbial assessment was done for detection of colony forming units (CFU from the plaque samples which were collected on 0 day and 21st day, both before brushing and after brushing. Results shown a significant reduction in all the parameters and the reduction was more significant in active and inactive ionic toothbrush users. It was concluded that both active and inactive ionic toothbrushes reduced the plaque index and gingival bleeding index scores significantly and active ionic tooth brushes were more effective as compared to inactive ionic toothbrushes. There was no soft tissue trauma following the use of both type of toothbrushes, which showed that ionic toothbrushes were equally safe for regular long-term use.

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

    KAUST Repository

    Rahaman, Md. Saifur

    2014-01-01

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

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

    NARCIS (Netherlands)

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

    2012-01-01

    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 with

  12. Effects of Chairside Polishing and Brushing on Surface Roughness of Acrylic Denture Base Resins

    Institute of Scientific and Technical Information of China (English)

    Seung-Kyun Kim; Ju-Mi Park; Min-Ho Lee; Jae-Youn Jung; Shipu Li; Xinyu Wang

    2009-01-01

    The effects of 3 chairside polishing kits and mechanical brushing on the surface roughness of 3 different acrylic denture base resins were compared. Acrylic denture base resins (auto-polymerizing, heat-polymerizing, injected heat-polymerizing resins) were examined after a tungsten carbide bur, and after chairside polishing using 3 polishing kits and pumice. The specimens were subjected to mechanical brushing using a wear tester to simulate 30 000 strokes of brushing. The surface roughness of the acrylic denture base resin specimens was measured using a contact pro-filometer. After the test, the random polished acrylic resins were evaluated by scanning electron mi-croscopy (SEM) and atomic force microscopy (AFM). Acrylic denture base resins polished using the 3 types of polishing kits had a smoother surface than those finished with the tungsten carbide bur (p <0.05). The surface of the resin polished by a TC cutter exceeded the Ra of 0.2 μm (p<0.05). The auto-polymerizing resin showed a significantly higher surface roughness than the heat-polymerizing resin and injected heat-polymerizing resin (p>0.05). In the case of polishing step wise, there was almost no change in surface roughness after brushing (p>0.05).

  13. EVALUATING THE IMPACT OF BRUSH CLEARING ON RECHARGE TO A KARST AQUIFER

    Science.gov (United States)

    My hypothesis is that brush removal will increase recharge, and this will be reflected in drip rate and drip water chemistry in the cave below. The results from this study should contribute to the understanding of how environmental variables affect karst hydrology. This stu...

  14. Four DNA methylation biomarkers in biliary brush samples accurately identify the presence of cholangiocarcinoma

    Science.gov (United States)

    Andresen, Kim; Boberg, Kirsten Muri; Vedeld, Hege Marie; Honne, Hilde; Jebsen, Peter; Hektoen, Merete; Wadsworth, Christopher A.; Clausen, Ole Petter; Lundin, Knut E.A.; Paulsen, Vemund; Foss, Aksel; Mathisen, Øystein; Aabakken, Lars; Schrumpf, Erik; Lothe, Ragnhild A.

    2015-01-01

    Early detection of the highly aggressive malignancy cholangiocarcinoma (CCA) remains a challenge but has the potential to render the tumor curable by surgical removal. This study evaluates a biomarker panel for the diagnosis of CCA by DNA methylation analyses of biliary brush samples. The methylation status of 13 candidate genes (CDO1, CNRIP1, DCLK1, FBN1, INA, MAL, SEPT9, SFRP1, SNCA, SPG20, TMEFF2, VIM, and ZSCAN18) was investigated in 93 tissue samples (39 CCAs and 54 nonmalignant controls) using quantitative methylation‐specific polymerase chain reaction. The 13 genes were further analyzed in a test series of biliary brush samples (15 CCAs and 20 nonmalignant primary sclerosing cholangitis controls), and the methylation status of the four best performing markers was validated (34 CCAs and 34 primary sclerosing cholangitis controls). Receiver operating characteristic curve analyses were used to evaluate the performance of individual biomarkers and the combination of biomarkers. The 13 candidate genes displayed a methylation frequency of 26%‐82% in tissue samples. The four best‐performing genes (CDO1, CNRIP1, SEPT9, and VIM) displayed individual methylation frequencies of 45%‐77% in biliary brushes from CCA patients. Across the test and validation biliary brush series, this four‐gene biomarker panel achieved a sensitivity of 85% and a specificity of 98%, with an area under the receiver operating characteristic curve of 0.944. Conclusion: We report a straightforward biomarker assay with high sensitivity and specificity for CCA, outperforming standard brush cytology, and suggest that the biomarker panel, potentially in combination with cytological evaluation, may improve CCA detection, particularly among primary sclerosing cholangitis patients. (Hepatology 2015;61:1651–1659) PMID:25644509

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

    Science.gov (United States)

    Varin, Kari J Moses; Cohen, Yoram

    2014-12-15

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

  16. Evaluation of a brushing machine for estimating density of spider mites on grape leaves.

    Science.gov (United States)

    Macmillan, Craig D; Costello, Michael J

    2015-12-01

    Direct visual inspection and enumeration for estimating field population density of economically important arthropods, such as spider mites, provide more information than alternative methods, such as binomial sampling, but is laborious and time consuming. A brushing machine can reduce sampling time and perhaps improve accuracy. Although brushing technology has been investigated and recommended as a useful tool for researchers and integrated pest management practitioners, little work to demonstrate the validity of this technique has been performed since the 1950's. We investigated the brushing machine manufactured by Leedom Enterprises (Mi-Wuk Village, CA, USA) for studies on spider mites. We evaluated (1) the mite recovery efficiency relative to the number of passes of a leaf through the brushes, (2) mite counts as generated by the machine compared to visual counts under a microscope, (3) the lateral distribution of mites on the collection plate and (4) the accuracy and precision of a 10% sub-sample using a double-transect counting grid. We found that about 95% of mites on a leaf were recovered after five passes, and 99% after nine passes, and mite counts from brushing were consistently higher than those from visual inspection. Lateral distribution of mites was not uniform, being highest in concentration at the center and lowest at the periphery. The 10% double-transect pattern did not result in a significant correlation with the total plate count at low mite density, but accuracy and precision improved at medium and high density. We suggest that a more accurate and precise sample may be achieved using a modified pattern which concentrates on the center plus some of the adjacent area. PMID:26459377

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

    International Nuclear Information System (INIS)

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

  18. Increased photocatalytic activity of tube-brush-like ZnO nanostructures fabricated by using PVP nanofibers as templates

    International Nuclear Information System (INIS)

    Highlights: • We obtained the tube-brush-like ZnO nanostructures. • We used polyvinylpyrrolidone (PVP) nanofibers used as templates by ALD and hydrothermal method to prepare tube-brush-like ZnO nanostructure. • The tube-brush-like ZnO nanostructures showed higher photocatalytic activity, the degradation of Rhodamine B (RhB) was up to 98% after 2 h of irradiation. - Abstract: The tube-brush-like ZnO nanostructures were synthesized by hydrothermal method using electrospinning polyvinylpyrrolidone (PVP) nanofibers as templates. The photocatalytic activity of as-grown samples was investigated by photo-degradation of Rhodamine B (RhB). The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV/visible absorption spectroscopy (UV–vis) and photoluminescence (PL) spectroscopy. It was found that the morphologies of the prepared ZnO were tube-brush-like nanostructures. With the grown time increasing, the crystal and the optical properties were improved. In the photocatalytic experiment, the tube-brush-like ZnO nanostructures photocatalytic activity was enhanced the degradation of RhB was up to 98% after 2 h of irradiation. The tube-brush-like ZnO nanostructures showed higher photocatalytic activity because of the special surface morphology

  19. Photo-induced in situ crosslinking of polymer brushes with dimethyl maleimide moieties for dynamically stimulating stem cell differentiation.

    Science.gov (United States)

    Arisaka, Yoshinori; Nishijima, Yuka; Yusa, Shin-Ichi; Takeda, Naoya

    2016-09-01

    We designed photo-crosslinkable polymer brushes with dimethylmaleimide moieties, in order to demonstrate dynamic stimulation of cell differentiation in mesenchymal stem cells (MSCs). The polymer brushes were synthesized by surface-initiated reversible addition fragmentation chain transfer polymerization using dimethylmaleimide ethyl methacrylate and methyl methacrylate on a chain transfer agent-immobilized glass surface. The polymer brushes were crosslinked by photodimerization of the dimethylmaleimide moieties within polymer chains with stem cells present on the surface. In order to evaluate the effects of in situ photo-induced crosslinking of the polymer brushes on gene expression of stem cells, human bone marrow MSCs were cultured under static and dynamic culture conditions for 7 days. Expression of the osteocalcin (Ocn) gene in MSCs was used as an indicator of osteoblast differentiation under dynamic culture conditions. Structural conversion from non-crosslinked polymer brushes to crosslinked polymer brushes increased the expression of Ocn by 1.4-fold in the presence of adhered cells, compared with non-crosslinked polymer brushes under static culture conditions. These results suggest that MSCs recognized surface conversion from non-crosslinked to crosslinked structures, which resulted in altered differentiation lineages. Therefore, photo-crosslinkable surfaces with dimethyl maleimide moieties are potential novel materials for dynamically stimulating MSC differentiation. PMID:27255343

  20. A comparative study of the efficacy of four different bristle designs of tooth brushes in plaque removal

    Directory of Open Access Journals (Sweden)

    Sripriya N

    2007-06-01

    Full Text Available Background : The aim of the study was to compare the efficacy of four most commonly used bristle designs of toothbrushes in plaque removal. Materials and Methods : The study was a randomized 4 cell, examiner blind cross-over design assessing the plaque removal efficacy of all four brushes on a single occasion. Sixteen subjects aged 14-15 years participated in the study. On day 1 of each test period, the subjects were rendered plaque free and were asked to suspend oral hygiene practices for 24 hours. On day 2, the subjects were scored for plaque prior to brushing using the Turesky-Gilmore modification of Quigley-Hein plaque index. The subjects then brushed with the allocated toothbrush for 2 minutes and the post-brushing plaque scores were assessed. A wash-out period of 4 days was allowed between the test periods. Results : All the brushes showed a significant reduction in the post-brushing plaque scores ( p < 0.001. The mean reduction in the plaque scores for all the brushes was around 53%. The percentage plaque reduction was greater in the anterior surface than the posterior surface (59.6 ± 7.45% vs. 49.83 ± 4.35%. The percentage plaque reductions in the upper, lower, buccal and lingual surfaces were similar. No significant difference in the reduction of plaque scores between the four brushes was seen. Conclusion : The data derived from the study supports the contention of many researchers that there is no single superior design of manual toothbrush. Though minor and some site differences in favor of the brushes were seen, they were not statistically significant.

  1. Physicochemical Properties of 'Particle Brush'-Based Materials: Using Polymer Graft Modification to Tailor Particle Interactions

    Science.gov (United States)

    Schmitt, Michael D.

    The advent of surface-initiated controlled radical polymerization techniques has allowed a new class of hybrid polymer-grafted nanoparticles, known as eparticle brushes,f to be realized. By grafting polymers from the surface, interactions between particles can be tuned using the precise control over graft architecture (i.e. chain length, dispersity, particle size, and grafting density) afforded by controlled radical polymerizations. Previously, a transition from particle-like to polymer-like interactions in small particles with increasing graft length has been observed. In the limit of long graft lengths, the polymer chains impart new interactions between particles, such as entanglements. These results outline a rich, but largely unexplored parameter space. The present thesis further elucidates the extent to which polymer graft modification facilitates new interaction types between particles and the dependence of those interactions on chain conformation. Specifically, the mechanical properties, processability, phase separation, and vibrational modes of particle brushes are examined. A dependence of the mechanical properties of particle brush assemblies on particle size is accurately captured by accounting for differences in chain conformation between particles of different sizes using a simple scaling model. Further tailoring of mechanical characteristics in weak particle brush assemblies can be achieved using appropriate homopolymer additives to form two-component systems. Improved mechanical properties are accompanied by a significant enhancement in particle processability that allows application of previously unusable processing methods. Considering more complex systems, mesoscale phase separation of nanoparticles is demonstrated for the first time by blending of particle brushes with different graft polymers. Polymer graft modification is seen to not only strengthen and introduce new interactions, but also tune particle properties. Vibrational modes of

  2. Chemical bath deposition of textured and compact zinc oxide thin films on vinyl-terminated polystyrene brushes

    Science.gov (United States)

    Blumenstein, Nina J; Hofmeister, Caroline G; Lindemann, Peter; Huang, Cheng; Baier, Johannes; Leineweber, Andreas; Wöll, Christof; Schimmel, Thomas

    2016-01-01

    Summary In this study we investigated the influence of an organic polystyrene brush on the deposition of ZnO thin films under moderate conditions. On a non-modified SiOx surface, island growth is observed, whereas the polymer brush induces homogeneous film growth. A chemical modification of the polystyrene brushes during the mineralization process occurs, which enables stronger interaction between the then polar template and polar ZnO crystallites in solution. This may lead to oriented attachment of the crystallites so that the observed (002) texture arises. Characterization of the templates and the resulting ZnO films were performed with ζ-potential and contact angle measurements as well as scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD). Infrared spectroscopy (IR) measurements were used to investigate the polystyrene brushes before and after modification. PMID:26925358

  3. Mechanism of nanoparticle actuation by responsive polymer brushes: from reconfigurable composite surfaces to plasmonic effects

    Science.gov (United States)

    Roiter, Yuri; Minko, Iryna; Nykypanchuk, Dmytro; Tokarev, Ihor; Minko, Sergiy

    2011-12-01

    The mechanism of nanoparticle actuation by stimuli-responsive polymer brushes triggered by changes in the solution pH was discovered and investigated in detail in this study. The finding explains the high spectral sensitivity of the composite ultrathin film composed of a poly(2-vinylpyridine) (P2VP) brush that tunes the spacing between two kinds of nanoparticles--gold nanoislands immobilized on a transparent support and gold colloidal particles adsorbed on the brush. The optical response of the film relies on the phenomenon of localized surface plasmon resonances in the noble metal nanoparticles, giving rise to an extinction band in visible spectra, and a plasmon coupling between the particles and the islands that has a strong effect on the band position and intensity. Since the coupling is controlled by the interparticle spacing, the pH-triggered swelling-shrinking transition in the P2VP brush leads to pronounced changes in the transmission spectra of the hybrid film. It was not established in the previous publications how the actuation of gold nanoparticles within a 10-15 nm interparticle distance could result in the 50-60 nm shift in the absorbance maximum in contrast to the model experiments and theoretical estimations of several nanometer shifts. In this work, the extinction band was deconvoluted into four spectrally separated and overlapping contributions that were attributed to different modes of interactions between the particles and the islands. These modes came into existence due to variations in the thickness of the grafted polymeric layer on the profiled surface of the islands. In situ atomic force microscopy measurements allowed us to explore the behavior of the Au particles as the P2VP brush switched between the swollen and collapsed states. In particular, we identified an interesting, previously unanticipated regime when a particle position in a polymer brush was switched between two distinct states: the particle exposed to the surface of the

  4. Changes in the permeability and morphology of dentine surfaces after brushing with a Thai herbal toothpaste: A preliminary study

    OpenAIRE

    Vajrabhaya, La-Ongthong; Korsuwannawong, Suwanna; Harnirattisai, Choltacha; Teinchai, Chayada

    2016-01-01

    Objectives: The aim of this study was to evaluate dentine permeability after brushing with Twin Lotus®, Thai herbal toothpaste by comparing with Sensodyne Rapid Relief®, a commercial desensitizing toothpaste, and also after artificial saliva (AS) immersion or citric acid challenge. Materials and Methods: Dentine discs from human mandibular third molars were divided into three groups (n = 20) and brushed with either experimental toothpaste or water (control) for 2 min with an automated toothbr...

  5. Video Processing SoC for Low-Latency Real-Time Interactive Real-Brush Painting System

    OpenAIRE

    Claesen, Luc; Vandoren, Peter; Van Laerhoven, Tom; Motten, Andy; Nowicki, Domien; Van Reeth, Frank

    2010-01-01

    To reduce the learning curve and enhance expressiveness, Human Computer Interfaces continuously improve to mimic object interaction in the real environment. A novel digital painting system has been developed that provides the artist with the expressiveness of virtual painting by using real and wet brushes. The kernel of the system is an interactive canvas powered by an SoC-based real-time video processing of the detailed wet brush-canvas contact image. To enable realistic and fast painting in...

  6. Treatment of enterococcus faecalis bacteria by a helium atmospheric cold plasma brush with oxygen addition

    International Nuclear Information System (INIS)

    An atmospheric cold plasma brush suitable for large area and low-temperature plasma-based sterilization is designed. Results demonstrate that the He/O2 plasma more effectively kills Enterococcus faecalis than the pure He plasma. In addition, the sterilization efficiency values of the He/O2 plasma depend on the oxygen fraction in Helium gas. The atmospheric cold plasma brush using a proper ratio of He/O2 (2.5%) reaches the optimum sterilization efficiency. After plasma treatment, the cell structure and morphology changes can be observed by the scanning electron microscopy. Optical emission measurements indicate that reactive species such as O and OH play a significant role in the sterilization process.

  7. Self-Healing Superhydrophobic Fluoropolymer Brushes as Highly Protein-Repellent Coatings.

    Science.gov (United States)

    Wang, Zhanhua; Zuilhof, Han

    2016-06-28

    Superhydrophobic surfaces with micro/nanostructures are widely used to prevent nonspecific adsorption of commercial polymeric and/or biological materials. Herein, a self-healing superhydrophobic and highly protein-repellent fluoropolymer brush was grafted onto nanostructured silicon by surface-initiated atom transfer radical polymerization (ATRP). Both the superhydrophobicity and antifouling properties (as indicated for isolated protein solutions and for 10% blood plasma) are well repaired upon serious chemical degradation (by e.g. air plasma). This brush still maintains excellent superhydrophobicity and good antifouling properties even after 5 damage-repair cycles, which opens a new door to fabricate long-term antifouling coatings on various substrates that can be used in harsh environments. PMID:27305351

  8. Stable Poly(methacrylic acid Brush Decorated Silica Nano-Particles by ARGET ATRP for Bioconjugation

    Directory of Open Access Journals (Sweden)

    Marcello Iacono

    2015-08-01

    Full Text Available The synthesis of polymer brush decorated silica nano-particles is demonstrated by activator regeneration by electron transfer atom transfer radical polymerization (ARGET ATRP grafting of poly(tert-butyl methacrylate. ATRP initiator decorated silica nano-particles were obtained using a novel trimethylsiloxane derivatised ATRP initiator obtained by click chemistry. Comparison of de-grafted polymers with polymer obtained from a sacrificial initiator demonstrated good agreement up to 55% monomer conversion. Subsequent mild deprotection of the tert-butyl ester groups using phosphoric acid yielded highly colloidal and pH stable hydrophilic nano-particles comprising approximately 50% methacrylic acid groups. The successful bio-conjugation was achieved by immobilization of Horseradish Peroxidase to the polymer brush decorated nano-particles and the enzyme activity demonstrated in a conversion of o-phenylene diamine dihydrochloride assay.

  9. Thermoswitchable Janus Gold Nanoparticles with Stimuli-Responsive Hydrophilic Polymer Brushes.

    Science.gov (United States)

    Niu, Xiaoqin; Ran, Fen; Chen, Limei; Lu, Gabriella Jia-En; Hu, Peiguang; Deming, Christopher P; Peng, Yi; Rojas-Andrade, Mauricio D; Chen, Shaowei

    2016-05-01

    Well-defined thermoswitchable Janus gold nanoparticles with stimuli-responsive hydrophilic polymer brushes were fabricated by combining ligand exchange reactions and the Langmuir technique. Stimuli-responsive polydi(ethylene glycol) methyl ether methacrylate was prepared by addition-fragmentation chain-transfer polymerization. The polymer brushes were then anchored onto the nanoparticle surface by interfacial ligand exchange reactions with hexanethiolate-protected gold nanoparticles, leading to the formation of a hydrophilic (polymer) hemisphere and a hydrophobic (hexanethiolate) one. The resulting Janus nanoparticles showed temperature-switchable wettability, hydrophobicity at high temperatures, and hydrophilicity at low temperatures, due to thermally induced conformational transition of the polymer ligands. The results further highlight the importance of interfacial engineering in the deliberate functionalization of nanoparticle materials. PMID:27064754

  10. Synthesis and conformational characterization of functional di-block copolymer brushes for microarray technology

    International Nuclear Information System (INIS)

    Surface initiated polymerization (SIP) coupled with reversible addition-fragmentation chain transfer polymerization (RAFT) was used to functionalize microarray glass slides with block polymer brushes. N,N-dimethylacrylamide (DMA) and N-acryloyloxysuccinimide (NAS) (graft-poly[DMA-b-(DMA-co-NAS)]) brushes, with di-block architecture, were prepared from a novel RAFT chain transfer agent bearing a silanating moiety (RAFT silane) directly anchored onto the glass surfaces. Conformational characterization of the coatings was performed by Self Spectral Interference Fluorescence Microscopy (SSFM), an innovative technique that describes the location of a fluorescent DNA molecule relative to a surface with sub-nanometer accuracy. X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscopy (SEM) were used to characterize the coatings composition and morphology.

  11. Synthesis and conformational characterization of functional di-block copolymer brushes for microarray technology

    Science.gov (United States)

    Di Carlo, Gabriele; Damin, Francesco; Armelao, Lidia; Maccato, Chiara; Unlu, Selim; Spuhler, Philipp S.; Chiari, Marcella

    2012-02-01

    Surface initiated polymerization (SIP) coupled with reversible addition-fragmentation chain transfer polymerization (RAFT) was used to functionalize microarray glass slides with block polymer brushes. N,N-dimethylacrylamide (DMA) and N-acryloyloxysuccinimide (NAS) (graft-poly[DMA-b-(DMA-co-NAS)]) brushes, with di-block architecture, were prepared from a novel RAFT chain transfer agent bearing a silanating moiety (RAFT silane) directly anchored onto the glass surfaces. Conformational characterization of the coatings was performed by Self Spectral Interference Fluorescence Microscopy (SSFM), an innovative technique that describes the location of a fluorescent DNA molecule relative to a surface with sub-nanometer accuracy. X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscopy (SEM) were used to characterize the coatings composition and morphology.

  12. Properties and Strengthening Mechanism of Brush Plated Nanoparticle Reinforced Composite Coatings

    Institute of Scientific and Technical Information of China (English)

    DONG Shi-yun; XU Bin-shi; MA Shi-ning; TU Wei-yi

    2004-01-01

    Nanoparticle reinforced nickel matrix composite coatings, such as n-Al2O3/Ni, n-SiO2/Ni, n-SiC/Ni and n-TiO2/Ni, were fabricated by brush plating technique. Hardness, wear resistance and contact-fatigue resistance of the composite coatings were determined, and strengthening mechanism of the composite coatings was discussed. Results showed that the composite coatings had superior properties to the Ni metal coating. Compared with properties of brush plated Ni metal coating, the composite coatings had hardness over 1.5 times and wear resistance capability of about 2.5 times. The strengthening mechanism of the composite coatings mainly included fine-crystal grain effect, nanoparticle dispersion effect and dislocation effect.

  13. Assessing the Risk of Secondary Transfer Via Fingerprint Brush Contamination Using Enhanced Sensitivity DNA Analysis Methods.

    Science.gov (United States)

    Bolivar, Paula-Andrea; Tracey, Martin; McCord, Bruce

    2016-01-01

    Experiments were performed to determine the extent of cross-contamination of DNA resulting from secondary transfer due to fingerprint brushes used on multiple items of evidence. Analysis of both standard and low copy number (LCN) STR was performed. Two different procedures were used to enhance sensitivity, post-PCR cleanup and increased cycle number. Under standard STR typing procedures, some additional alleles were produced that were not present in the controls or blanks; however, there was insufficient data to include the contaminant donor as a contributor. Inclusion of the contaminant donor did occur for one sample using post-PCR cleanup. Detection of the contaminant donor occurred for every replicate of the 31 cycle amplifications; however, using LCN interpretation recommendations for consensus profiles, only one sample would include the contaminant donor. Our results indicate that detection of secondary transfer of DNA can occur through fingerprint brush contamination and is enhanced using LCN-DNA methods. PMID:26300550

  14. Tailored Poly(2-oxazoline) Polymer Brushes to Control Protein Adsorption and Cell Adhesion

    KAUST Repository

    Zhang, Ning

    2012-05-18

    POx bottle-brush brushes (BBBs) are synthesized by SIPGP of 2-isopropenyl-2-oxazoline and consecutive LCROP of 2-oxazolines on 3-aminopropyltrimethoxysilane-modified silicon substrates. The side chain hydrophilicity and polarity are varied. The impact of the chemical composition and architecture of the BBB upon protein (fibronectin) adsorption and endothelial cell adhesion are investigated and prove extremely low protein adsorption and cell adhesion on BBBs with hydrophilic side chains such as poly(2-methyl-2-oxazoline) and poly(2-ethyl-2-oxazoline). The influence of the POx side chain terminal function upon adsorption and adhesion is minor but the side chain length has a significant effect on bioadsorption. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    DEFF Research Database (Denmark)

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

    2007-01-01

    explants. By immunofluorescence microscopy, fat absorption caused a translocation of IAP from the enterocyte brush border to the interior of the cell, whereas other brush-border enzymes were unaffected. By electron microscopy, the translocation occurred by a rapid (5 min) induction of endocytosis via...... clathrin-coated pits. By 60 min, IAP was seen in subapical endosomes and along membranes surrounding fat droplets. IAP is a well-known lipid raft-associated protein, and fat absorption was accompanied by a marked change in the density and morphology of the detergent-resistant membranes harboring IAP. A...... IAP and may contribute to the appearance of the enzyme in serum and surfactant-like particles....

  16. Treatment of enterococcus faecalis bacteria by a helium atmospheric cold plasma brush with oxygen addition

    Science.gov (United States)

    Chen, Wei; Huang, Jun; Du, Ning; Liu, Xiao-Di; Wang, Xing-Quan; Lv, Guo-Hua; Zhang, Guo-Ping; Guo, Li-Hong; Yang, Si-Ze

    2012-07-01

    An atmospheric cold plasma brush suitable for large area and low-temperature plasma-based sterilization is designed. Results demonstrate that the He/O2 plasma more effectively kills Enterococcus faecalis than the pure He plasma. In addition, the sterilization efficiency values of the He/O2 plasma depend on the oxygen fraction in Helium gas. The atmospheric cold plasma brush using a proper ratio of He/O2 (2.5%) reaches the optimum sterilization efficiency. After plasma treatment, the cell structure and morphology changes can be observed by the scanning electron microscopy. Optical emission measurements indicate that reactive species such as O and OH play a significant role in the sterilization process.

  17. Treatment of enterococcus faecalis bacteria by a helium atmospheric cold plasma brush with oxygen addition

    Energy Technology Data Exchange (ETDEWEB)

    Chen Wei; Huang Jun; Wang Xingquan; Lv Guohua; Zhang Guoping [Key Laboratory of Soft Matter Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, 100190 Beijing (China); Du Ning; Liu Xiaodi; Guo Lihong [Department of Oral Biology, Peking University School and Hospital of Stomatology, 100080 Beijing (China); Yang Size [Key Laboratory of Soft Matter Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, 100190 Beijing (China); Fujian Key Laboratory for Plasma and Magnetic Resonance, Department of Aeronautics, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen 361005 (China)

    2012-07-01

    An atmospheric cold plasma brush suitable for large area and low-temperature plasma-based sterilization is designed. Results demonstrate that the He/O{sub 2} plasma more effectively kills Enterococcus faecalis than the pure He plasma. In addition, the sterilization efficiency values of the He/O{sub 2} plasma depend on the oxygen fraction in Helium gas. The atmospheric cold plasma brush using a proper ratio of He/O{sub 2} (2.5%) reaches the optimum sterilization efficiency. After plasma treatment, the cell structure and morphology changes can be observed by the scanning electron microscopy. Optical emission measurements indicate that reactive species such as O and OH play a significant role in the sterilization process.

  18. Response Of Bi-Level And Random Copolymer Brushes Based On Poly(N-Isopropylacrylamide) And Poly(Methacrylic Acid)

    International Nuclear Information System (INIS)

    Because conformations and interactions are intimately linked, the rich phase behavior exhibited by multicomponent polymer-modified interfaces, and in particular multicomponent polymer brushes, offers new opportunities for manipulating interfacial properties. Despite the widespread use of a variety of grafting to and grafting from approaches for making polymer brushes, there are few reports of synthesis and responsive behavior of stratified block copolymer brushes. In this presentation we describe our efforts to create bi-level and random copolymer brushes consisting of poly(N-isopropylacrylamide) and poly(methacrylic acid) using surface initiated, photoiniferter-mediated photopolymerization. Pre-addition of a source of deactivating radicals combined with judicious choice of photopolymerization conditions enables the formation of bi-level brushes. In situ, multi-angle ellipsometry measurements show that the blocks of the bi-level brushes actuate independently to changes in pH and temperature, but respond in concert to changes in ionic strength. Efforts to examine the nanoscale structure of these systems as a function of pH and temperature using neutron reflectometry will also be highlighted.

  19. Enhancement of charge-transport characteristics in polymeric films using polymer brushes

    DEFF Research Database (Denmark)

    Whiting, G.L.; Snaith, H.J.; Khodabakhsh, S.;

    2006-01-01

    We show that charge-transporting polymer chains in the brush conformation can be synthesized from a variety of substrates of interest, displaying a high degree of stretching and showing up to a 3 orders of magnitude increase in current density normal to the substrate as compared with a spin-coate......-coated film. These nanostructured polymeric films may prove to be suitable for electronic devices based on molecular semiconductors as current fabrication techniques often provide little control over film structure....

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

    DEFF Research Database (Denmark)

    Halberg, Kenneth A; Rainey, Stephanie M; Veland, Iben R; Neuert, Helen; Dornan, Anthony J; Klämbt, Christian; Davies, Shireen-Anne; Dow, Julian A T

    2016-01-01

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

  1. Receptors for short-chain fatty acids in brush cells at the gastric groove

    Directory of Open Access Journals (Sweden)

    Julia Anna-Maria Eberle

    2014-04-01

    Full Text Available In the stomach of rodents clusters of brush cells are arranged at the gastric groove, immediately at the transition zone from the non-glandular reservoir compartment to the glandular digestive compartment. Based on their taste cell-like molecular phenotype it has been speculated that the cells may be capable to sense constituents of the ingested food, however, searches for nutrient receptors have not been successful. In this study, it was hypothesized that the cells may express receptors for short-chain fatty acids, metabolites generated by microorganisms during the storage of ingested food in the murine forestomach, which lacks the acidic milieu of more posterior regions of the stomach and is colonized with numerous microbiota. Experimental approaches, including RT-PCR analysis and immunohistochemical studies, revealed that the majority of these brush cells express the G-protein coupled receptor types GPR41 (FFAR3 and GPR43 (FFAR2, which are activated by short-chain fatty acids. Both, the GPR41 receptor proteins as well as an appropriate G-protein, α-gustducin, were found to be segregated at the apical brush border of the cells, indicating a direct contact with the luminal content of this gastric region. The exposure of microvillar processes with appropriate receptors and signaling elements to the gastric lumen suggests that the brush cells may in fact be capable to sense the short-chain fatty acids which originate from fermentation processes during the retention of ingested food in the anterior part of the stomach.

  2. Uptake and kinetics of 226Ra, 210Pb and 210Po in big sage brush

    International Nuclear Information System (INIS)

    Root uptake of 226Pb and 210Po by mature sage brush was studied using a soil injection method for spiking the soil with minimal root disturbance. The main objective was to measure vegetation concentrations and determine concentration ratios (CR's) due to root uptake as a function of time in mature big sage brush. Concentration ratios obtained in mature vegetation and in steady-state situations may be valuable in assessing the impact of uranium mining and milling. The vegetation was sampled approximately every 3 mo for A 2 y period. Significant levels of activity were detected in the vegetation beginning at the first sampling (81 d after soil injection for 226Ra, 28 d for 210Pb and 210Po). There was an exponential decrease in concentration to an apparent steady state value. Mean values (geometric) of the data pooled over the second year period indicated that steady-state Cr's for 226Ra, 210Pb and 210Po, as determined in mature sage brush, were 0.04, 0.009, and 0.08, respectively. Investigations were also carried out to verify the suitability of soil injection for uptake studies and to evaluate the time dependence of 226Ra leaching from sage brush leaves. The soil injection method was determined to produce, on the average, uptake equivalent to that produce by a uniform soil distribution, however, the variety of uptake for plants growing in injected soil was higher than for plants growing in uniformly contaminated soil. A three compartment mathematical model was formulated to help understand mechanisms of plant uptake and to predict, if possible, the concentration of 226Ra, 210Po in vegetation as a function of time after soil spiking

  3. Implementation of Brushed DC Motor Control in LabVIEW FPGA

    OpenAIRE

    K. Lamár; A. G. Kocsis

    2013-01-01

    The paper introduces the fundamentals of motor control. It explains the basic equations and introduces the control diagram of the brushed DC motor. It introduces the four quadrant DC chopper circuit and the basic methods to operate it. After that, it explains the fundamentals of the current control of DC motors and its two basic methods: the pulse width modulation and the hysteresis current control. Finally it gives a short example of the practical implementation of the hysteresis current con...

  4. Natural Selection at the Brush-Border: Adaptations to Carbohydrate Diets in Humans and Other Mammals

    OpenAIRE

    Pontremoli, Chiara; Mozzi, Alessandra; Forni, Diego; Cagliani, Rachele; Pozzoli, Uberto; Menozzi, Giorgia; Vertemara, Jacopo; Bresolin, Nereo; Clerici, Mario; Sironi, Manuela

    2015-01-01

    Dietary shifts can drive molecular evolution in mammals and a major transition in human history, the agricultural revolution, favored carbohydrate consumption. We investigated the evolutionary history of nine genes encoding brush-border proteins involved in carbohydrate digestion/absorption. Results indicated widespread adaptive evolution in mammals, with several branches experiencing episodic selection, particularly strong in bats. Many positively selected sites map to functional protein reg...

  5. Captures of Boll Weevils (Coleoptera: Curculionidae) in Relation to Trap Orientation and Distance From Brush Lines.

    Science.gov (United States)

    Spurgeon, Dale W

    2016-04-01

    Eradication programs for the boll weevil (Anthonomus grandis grandis Boheman) rely on pheromone-baited traps to trigger insecticide treatments and monitor program progress. A key objective of monitoring in these programs is the timely detection of incipient weevil populations to limit or prevent re-infestation. Therefore, improvements in the effectiveness of trapping would enhance efforts to achieve and maintain eradication. Association of pheromone traps with woodlots and other prominent vegetation are reported to increase captures of weevils, but the spatial scale over which this effect occurs is unknown. The influences of trap distance (0, 10, and 20 m) and orientation (leeward or windward) to brush lines on boll weevil captures were examined during three noncropping seasons (October to February) in the Rio Grande Valley of Texas. Differences in numbers of captured weevils and in the probability of capture between traps at 10 or 20 m from brush, although often statistically significant, were generally small and variable. Variations in boll weevil population levels, wind directions, and wind speeds apparently contributed to this variability. In contrast, traps closely associated with brush (0 m) generally captured larger numbers of weevils, and offered a higher probability of weevil capture compared with traps away from brush. These increases in the probability of weevil capture were as high as 30%. Such increases in the ability of traps to detect low-level boll weevil populations indicate trap placement with respect to prominent vegetation is an important consideration in maximizing the effectiveness of trap-based monitoring for the boll weevil. PMID:26719592

  6. Comparison of two pig intestinal brush border peptidases with the corresponding renal enzymes

    DEFF Research Database (Denmark)

    Norén, O; Sjöström, H; Danielsen, Erik Michael; Staun, M; Jeppesen, L; Svensson, B

    1979-01-01

    -glutamyl-transferase was found to be identical to that of the kidney enzyme. The electrophoretic mobilities of dipeptidyl peptidase IV from the two organs differed greatly. The difference was almost abolished by treatment with neuraminidase, suggesting that the variation in mobility was due to different contents of sialic...... acid. It is suggested that the intestinal brush border peptidases, dipeptidyl peptidase IV and gamma-glutamyltransferase, are closely related to the corresponding enzymes obtained from the kidney....

  7. A novel shortened electrospun nanofiber modified with a 'concentrated' polymer brush

    Directory of Open Access Journals (Sweden)

    Chiaki Yoshikawa, Kun Zhang, Ewelina Zawadzak and Hisatoshi Kobayashi

    2011-01-01

    Full Text Available We report the fabrication of shortened electrospun polymer fibers with a well-defined concentrated polymer brush. We first prepared electrospun nanofibers from a random copolymer of styrene and 4-vinylbenzyl 2-bromopropionate, with number-average molecular weight Mn=105 200 and weight-average molecular weight Mw=296 700 (Mw/Mn=2.82. The fibers had a diameter of 593±74 nm and contained initiating sites for surface-initiated atom transfer radical polymerization (SI-ATRP. Then, SI-ATRP of hydrophilic styrene sodium sulfonate (SSNa was carried out in the presence of a free initiator and the hydrophobic fibers. Gel permeation chromatography confirmed that Mn and Mw/Mn values were almost the same for free polymers and graft polymers. Mn agreed well with the theoretical prediction, and Mw/Mn was relatively low (<1.3 in all the examined cases, indicating that this polymerization proceeded in a living manner. Using the values of the graft amount measured by Fourier transform infrared spectroscopy, the surface area, and Mn, we calculated the graft density σ as 0.22 chains nm−2. This value was nearly equal to the density obtained on silicon wafers (σ=0.24 chains nm−2, which is categorized into the concentrated brush regime. Finally, we mechanically cut the fibers with a concentrated poly(SSNa brush by a homogenizer. With increasing cutting time, the fiber length became shorter and more homogenous (11±17 μm after 3 h. The shortened fibers exhibited excellent water dispersibility owing to the hydrophilic poly(SSNa brush layer.

  8. "Bottle Brush Sign"-Spinal Meningeal Disease on 18F-FDG PET-CT Scan.

    Science.gov (United States)

    Riaz, Saima; Naz, Fozia; Bashir, Humayun; Niazi, Imran Khalid

    2016-09-01

    A 30-year-old man with a history of stage IV AE diffuse large cell lymphoma of left proximal humerus presented with new onset lower limb weakness at completion of chemotherapy. The F-FDG PET-CT scan showed increased intraspinal uptake from T12 to S1 vertebrae with unique "bottle brush" appearance in keeping with spinal meningeal disease. The leptomeningeal disease was further confirmed on correlative MRI scan. PMID:27405033

  9. Synthesis and Characterization of Brush Copolymer Poly (propylene oxide)-graft-Poly(N,N-dimethylaminoethyl methacrylate)

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wen-qian

    2016-01-01

    In this paper, a amphiphilic brush copolymer poly (propylene oxide)-graft -poly (N,N-dimethylaminoethyl methacrylate) (PPO-g-PDMAEMA) was successfully prepared via the combine of anionic ring opening polymerization and atom transfer radical polymerization(ATRP). The target products were confirmed by GPC and 1H NMR. This well-defined copolymer can supply a promising material as drug and gene carriers and protective materials.

  10. Entropic interaction chromatography: separating proteins on the basis of size using end-grafted polymer brushes.

    Science.gov (United States)

    Pang, Peter; Koska, Jürgen; Coad, Bryan R; Brooks, Donald E; Haynes, Charles A

    2005-04-01

    Partitioning of a macromolecule into the interfacial volume occupied by a grafted polymer brush decreases the configurational entropy (DeltaSbrush(c)) of the terminally attached linear polymer chains due to a loss of free volume. Self-consistent field theory (SCF) calculations are used to show that DeltaSbrush(c) is a strong function of both the size (MWp) of the partitioning macromolecule and the depth of penetration into the brush volume. We further demonstrate that the strong dependence of DeltaSbrush(c) on MWp provides a novel and powerful platform, which we call entropic interaction chromatography (EIC), for efficiently separating mixtures of proteins on the basis of size. Two EIC columns, differing primarily in polymer grafting density, were prepared by growing a brush of poly(methoxyethyl acrylamide) chains on the surface of a wide-pore (1,000-A pores, 64-microm diameter rigid beads) resin (Toyopearl AF-650M) bearing surface aldehyde groups. Semipreparative 0.1-L columns packed with either EIC resin provide reduced-plate heights of 2 or less for efficient separation of globular protein mixtures over at least three molecular-weight decades. Protein partitioning within these wide-pore EIC columns is shown to be effectively modeled as a thermodynamically controlled process, allowing partition coefficients (K(P)) and elution chromatograms to be accurately predicted using a column model that combines SCF calculation of K(P) values with an equilibrium-dispersion type model of solute transport through the column. This model is used to explore the dependence of column separation efficiency on brush properties, predicting that optimal separation of proteins over a broad MWp range is achieved at low to moderate grafting densities and intermediate chain lengths. PMID:15706591

  11. Synthesis of PMMA-co-PMAA copolymer brush on multi-wall carbon nanotubes

    Czech Academy of Sciences Publication Activity Database

    Slobodian, P.; Svoboda, P.; Říha, Pavel; Bořuta, R.; Sáha, P.

    2012-01-01

    Roč. 2, č. 3 (2012), s. 221-226. ISSN 2161-4881 Grant ostatní: OP VaVpI(XE) CZ.1.05/2.1.00/03.0111; UTB Zlín(CZ) IGA/FT/2012/ 022 Institutional research plan: CEZ:AV0Z20600510 Keywords : car bon nanotubes * functionalization * PMMA * PMAA * polymer brush Subject RIV: JI - Composite Materials

  12. Perfluorocarbon thin films and polymer brushes on stainless steel 316L for control of interfacial properties

    OpenAIRE

    Kruszewski, Kristen M; Gawalt, Ellen S.

    2011-01-01

    Perfluorocarbon thin films and polymer brushes were formed on stainless steel 316L (SS316L) to control the surface properties of the metal oxide. Substrates modified with the films were characterized using diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), contact angle analysis, atomic force microscopy (AFM), and cyclic voltammetry (CV). Perfluorooctadecanoic acid (PFOA) was used to form thin films by self-assembly on the surface of SS316L. Polypentafluorostyrene (PFS) poly...

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

    Science.gov (United States)

    Faust, James J.

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

  14. Deactivation of Enterococcus Faecalis Bacteria by an Atmospheric Cold Plasma Brush

    Science.gov (United States)

    Chen, Wei; Huang, Jun; Du, Ning; Liu, Xiao-Di; Lv, Guo-Hua; Wang, Xing-Quan; Zhang, Guo-Ping; Guo, Li-Hong; Yang, Si-Ze

    2012-07-01

    An atmospheric cold plasma brush suitable for large area and low-temperature plasma-based sterilization is designed and used to treat enterococcus faecalis bacteria. The results show that the efficiency of the inactivation process by helium plasma is dependent on applied power and exposure time. After plasma treatments, the cell structure and morphology changes can be observed by scanning electron microscopy. Optical emission measurements indicate that reactive species such as O and OH play a significant role in the sterilization process.

  15. CT brush and CancerZap!: two video games for computed tomography dose minimization

    OpenAIRE

    Alvare, Graham; Gordon, Richard

    2015-01-01

    Background X-ray dose from computed tomography (CT) scanners has become a significant public health concern. All CT scanners spray x-ray photons across a patient, including those using compressive sensing algorithms. New technologies make it possible to aim x-ray beams where they are most needed to form a diagnostic or screening image. We have designed a computer game, CT Brush, that takes advantage of this new flexibility. It uses a standard MART algorithm (Multiplicative Algebraic Reconstru...

  16. Quantifying bacterial adhesion on antifouling polymer brushes via single-cell force spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Rodriguez-Emmenegger, Cesar; Janel, S.; de los Santos Pereira, Andres; Bruns, M.; Lafont, F.

    2015-01-01

    Roč. 6, č. 31 (2015), s. 5740-5751. ISSN 1759-9954 R&D Projects: GA ČR(CZ) GJ15-09368Y; GA MŠk(CZ) ED1.1.00/02.0109 Grant ostatní: OPPK(XE) CZ.2.16/3.1.00/21545 Institutional support: RVO:61389013 Keywords : antifouling polymer brushes * single-cell force spectroscopy * bacterial adhesion Subject RIV: BO - Biophysics Impact factor: 5.520, year: 2014

  17. Cimetidine transport in isolated brush border membrane vesicles from bovine choroid plexus

    International Nuclear Information System (INIS)

    The purpose of this study was to elucidate the mechanisms involved in the transport of cimetidine across the brush border membrane of choroid plexus epithelium. Brush border membrane vesicles were prepared from bovine choroid plexus and the uptake of [3H]cimetidine was studied using the methods of rapid vacuum filtration and scintillation counting. Cimetidine accumulated in the vesicles with time reaching equilibrium within 2 hr. The amount of cimetidine taken up by the vesicles at equilibrium decreased with increasing extravesicular media osmolarity suggesting that cimetidine accumulates in an osmotically reactive intravesicular space. Binding of cimetidine to the membrane was estimated to be less than 18%. Michaelis-Menten studies demonstrated that cimetidine transport involved both a saturable and a nonsaturable component. The Vmax and Km (mean +/- S.E.) were 16.7 +/- 5.9 pmol/sec/mg protein and 58.1 +/- 3.1 microM, respectively, suggesting that cimetidine is transported across the choroid plexus brush border membrane with a lower affinity and a higher capacity than across the renal brush border membrane. The organic cation, quinidine (0.1 mM), and the amino acid, histidine (20 mM), both significantly reduced the initial, but not the equilibrium, uptake of cimetidine. However, high concentrations (5 mM) of more polar organic cations including tetraethylammonium, as well as of several organic anions including salicylate did not inhibit cimetidine transport. Studies with unlabeled cimetidine revealed a countertransport phenomenon. Attempts to drive the concentrative uptake of cimetidine with various ion gradients were unsuccessful. Of note was the fact that an outwardly directed proton gradient could significantly accelerate the uptake of cimetidine

  18. Performance and erosion of a tungsten brush limiter exposed at the TEXTOR tokamak

    International Nuclear Information System (INIS)

    To examine the performance of a castellated structure under plasma loading, a hemispherical solid tungsten brush limiter was exposed to the plasma in the TEXTOR-94 tokamak. Due to the thermally isolated column of W segments, IR camera showed a non-uniform temperature distribution. The maximum incident power density was calculated to be about 35-40 MW/m2. Concerning impurity generation, the structure did not show any particular effects. During plasma exposure, only some minor cracks developed in one of the columns, however, the crack propagation was interrupted by a groove. It can be concluded that the W brush limiter had comparable performance and superior mechanical behaviour compared to a solid W limiter. To study erosion and long-range transport of W atoms, a graphite limiter was exposed simultaneously with the brush limiter. As a result, the deposited W atoms via long-range transportation were estimated to be 1015 cm-2 shot-1 at 46.5 cm from the plasma centre of TEXTOR

  19. Gradation of proteins and cells attached to the surface of bio-inert zwitterionic polymer brush.

    Science.gov (United States)

    Li, Lifu; Nakaji-Hirabayashi, Tadashi; Kitano, Hiromi; Ohno, Kohji; Kishioka, Takahiro; Usui, Yuki

    2016-08-01

    A self-assembled monolayer (SAM) of a 2-bromoisobutyryl end group-carrying initiator for atom transfer radical polymerization (ATRP) was constructed on the surface of silicon wafer or glass substrates via a silane-coupling reaction. When the initiator SAM was irradiated with UV light at 254nm, the surface density of bromine atoms was reduced by the scission of CBr bonds as observed by XPS. With the surface-initiated ATRP of the zwitterionic vinyl monomer, carboxymethyl betaine (CMB), the surface density of PCMB brushes could be easily varied by changing the irradiation period of UV light prior to the polymerization. Furthermore, by using a UV-cut shutter sliding above the initiator SAM-modified substrate at a constant speed, the degree of bromine atom removal could be linearly varied along the direction of movement of the shutter. Consequently, the amount of both proteins adsorbed and cells adhered to the PCMB brush-covered substrate could easily be controlled by the gradation of the surface density of PCMB brushes, which suppressed protein adsorption and cell adhesion. Such a technique is very simple and useful for the regulation of the surface density of adsorbed proteins and adhered cells on an originally bio-inert surface. PMID:27085477

  20. Characterization of Swollen States of Polyelectrolyte Brushes in Salt Solution by Neutron Reflectivity

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Motoyasu; Mitamura, Koji; Takahara, Atsushi [Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Terada, Masami [JST, ERATO (Japan); Yamada, Norifumi L, E-mail: takahara@cstf.kyushu-u.ac.jp [High Energy Accelerator Research Organization (KEK) (Japan)

    2011-01-01

    Cationic and zwitterionic polyelectrolyte brushes on quartz substrate were synthesized by surface-initiated atom transfer radical polymerization of 2-(methacryloyloxy)-ethyltrimethylammonium chloride (MTAC) and 2-(methacryloyloxy)ethyl phosphorylcholine (MPC). The effects of ionic strength on brush structure are investigated by neutron reflectivity (NR) in NaCl deuterium oxide (D{sub 2}O) solutions. We observed that poly(MTAC) chains were drastically shrunk at concentrations above 0.1 M NaCl/D{sub 2}O, which may be the change in charge-screening effect against ions on poly(MTAC). On the other hand, effect of salt concentration on a swollen state of poly(MPC) brush was negligible, even at the high concentration (5.0 M) close to saturation. The behaviour of poly(MPC) in salt aqueous solution is completely different from that of poly(MTAC), which may arise from the unique interaction properties, neutral nature, and hydrated water structure of phosphorylcholine units.

  1. Spherical brushes within spherical cavities: a self-consistent field and Monte Carlo study.

    Science.gov (United States)

    Cerdà, Juan J; Sintes, Tomás; Toral, Raúl

    2009-10-01

    We present an extensive numerical study on the behavior of spherical brushes confined into a spherical cavity. Self-consistent field (SCF) and off-lattice Monte Carlo (MC) techniques are used in order to determine the monomer and end-chain density profiles and the cavity pressure as a function of the brush properties. A comparison of the results obtained via SCF, MC, and the Flory theory for polymer solutions reveals SCF calculations to be a valuable alternative to MC simulations in the case of free and softly compressed brushes, while the Flory's theory accounts remarkably well for the pressure in the strongly compressed regime. In the range of high compressions, we have found the cavity pressure P to follow a scale relationship with the monomer volume fraction v, P approximately v(alpha). SCF calculations give alpha=2.15+/-0.05, whereas MC simulations lead to alpha=2.73+/-0.04. The underestimation of alpha by the SCF method is explained in terms of the inappropriate account of the monomer density correlations when a mean field approach is used. PMID:19814569

  2. Cylindrical polymer brushes with dendritic side chains by iterative anionic reactions

    KAUST Repository

    Zhang, Hefeng

    2015-05-01

    We report in this paper an easy method for the synthesis of cylindrical polymer brushes with dendritic side chains through anionic reaction. The synthesis is accomplished by iteratively grafting a living block copolymer, polyisoprene-. b-polystyrenyllithium (PI-. b-PSLi), to the main chain and subsequently to the branches in a divergent way. PI segment is short and serves as a precursor for multifunctional branching unit. The grafting reaction involves two successive steps: i) epoxidation of internal double bonds of PI segments, either in main chain or side chains; ii) ring-opening addition to the resulting epoxy group by the living PI-. b-PSLi. Repeating the two steps affords a series of cylindrical polymer brushes with up to 3rd generation and extremely high molecular weight. The branching multiplicity depends on the average number of oxirane groups per PI segment, usually ca. 8 in the present work. The high branching multiplicity leads to tremendous increase in molecular weights of the cylindrical products with generation growth. Several series of cylindrical polymer brushes with tunable aspect ratios are prepared using backbones and branches with controlled lengths. Shape anisotropy is investigated in dilute solution using light scattering technique. Worm-like single molecular morphology with large persistence length is observed on different substrates by atomic force microscopy.

  3. Calcium uptake by brush-border and basolateral membrane vesicles in chick duodenum

    Energy Technology Data Exchange (ETDEWEB)

    Takito, J.; Shinki, T.; Sasaki, T.; Suda, T. (Showa Univ., Tokyo (Japan))

    1990-01-01

    Calcium uptake was compared between duodenal brush-border membrane vesicles (BBMV) and basolateral membrane vesicles (BLMV) isolated from vitamin D-deficient chicks and those injected with 625 ng of 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25(OH)2D3). The uptake by BBMV in the 1 alpha,25-(OH)2D3-treated birds attained a maximum (280% of the control) at 12 h and was maintained at an elevated level (210%) at 24 h after the injection of the vitamin. In contrast, ATP-dependent calcium uptake by BLMV reached a maximum (185% of the control) at 6 h and decreased to the control level at 24 h. The kinetic analysis revealed that 1 alpha,25(OH)2D3 increased Vmax values without any changes in apparent Km values in both BBMV and BLMV. The activity of ATP-dependent calcium uptake was localized exclusively in the basolateral membrane, and the activity was inhibited by vanadate (IC50, 1 microM), but not by oligomycin, theophylline, calmodulin, trifluoperazine, or calbindin D28K. These results indicate that calcium transport through both the brush-border and basolateral membranes is involved in the 1 alpha,25(OH)2D3-dependent intestinal calcium absorption. The initiation of calcium absorption by 1 alpha,25(OH)2D3 appears to be due to an increase in the rate of calcium efflux at the basolateral membrane rather than the rate at the brush-border membrane.

  4. Preparation of polystyrene brush film by radical chain-transfer polymerization and micromechanical properties

    Science.gov (United States)

    Zhao, Jing; Chen, Miao; An, Yanqing; Liu, Jianxi; Yan, Fengyuan

    2008-12-01

    A radical chain-transfer polymerization technique has been applied to graft-polymerize brushes of polystyrene (PSt) on single-crystal silicon substrates. 3-Mercapto-propyltrimethoxysilane (MPTMS), as a chain-transfer agent for grafting, was immobilized on the silicon surface by a self-assembling process. The structure and morphology of the graft-functionalized silicon surfaces were characterized by the means of contact-angle measurement, ellipsometric thickness measurement, Fourier transformation infrared (FTIR) spectroscopy, and atomic force microscopy (AFM). The nanotribological and micromechanical properties of the as-prepared polymer brush films were investigated by frictional force microscopy (FFM), force-volume analysis and scratch test. The results indicate that the friction properties of the grafted polymer films can be improved significantly by the treatment of toluene, and the chemically bonded polystyrene film exhibits superior scratch resistance behavior compared with the spin-coated polystyrene film. The resultant polystyrene brush film is expected to develop as a potential lubrication coating for microelectromechanical systems (MEMS).

  5. High temperature brush seal tuft testing of metallic bristles versus chrome carbide

    Science.gov (United States)

    Fellenstein, James A.; DellaCorte, Christopher; Moore, Kenneth D.; Boyes, Esther

    1996-01-01

    The tribology of brush seals is of considerable interest to turbine engine designers because bristle wear continues to limit long term seal performance and life. To provide better materials characterization and foster the development of improved seals, NASA Lewis has developed a brush seal tuft tester. In this test, a 'paintbrush' sample tuft is loaded under constant contact pressure against the outside diameter of a rotating journal. With this configuration a direct measurement of load and friction is made. Accurate wear rate measurements are possible due to the known contact pressure. Previously reported baseline research using this facility showed good data repeatability and wear morphology similar to published seal data. This paper extends and expands the database for candidate brush seal materials. A series of tuft tests were completed to evaluate the performance of five high temperature superalloy wires sliding against plasma sprayed nichrome-bonded chrome carbide. Wire materials were either nickel-chrome or cobalt-chrome based superalloys. Good corroboration of the tuft results with dynamic seal rig tests was observed; giving additional confidence in the tuft test as a screening and development tool.

  6. High Temperature Brush Seal Tuft Testing of Selected Nickel-Chrome and Cobalt-Chrome Superalloys

    Science.gov (United States)

    Fellenstein, James A.; DellaCorte, Christopher; Moore, Kenneth D.; Boyes, Esther

    1997-01-01

    The tribology of brush seals is of considerable interest to turbine engine designers because bristle wear continues to limit long term seal performance and life. To provide better materials characterization and foster the development of improved seals, NASA Lewis has developed a brush seal tuft tester. In this test, a 'paintbrush' sample tuft is loaded under constant contact pressure against the outside diameter of a rotating journal. With this configuration, load and friction are directly measured and accurate wear measurements are possible. Previously reported research using this facility showed excellent data repeatability and wear morphology similar to published seal data and dynamic rig tests. This paper is an update of the ongoing research into the tribology of brush seals. The effects of wire materials processing on seal wear and the tribological results for three journal coatings are discussed. Included in the materials processing were two nickel-chrome superalloys each processed to two different yield strengths. The results suggest that seal wear is dependent more on material composition than processing conditions.

  7. Isolation of epithelial cells from tooth brush and gender identification by amplification of SRY gene

    Directory of Open Access Journals (Sweden)

    A Vikram Simha Reddy

    2011-01-01

    Full Text Available Introduction: This study determines the importance of tooth brush from which DNA can be isolated and used for sex determination in forensic analysis. Materials and Methods: A total of 30 samples were collected and stored at room temperature for different periods of time interval. The epithelial cells adhered to the bristles of tooth brush were collected and genomic DNA was extracted and quantified using Nanodrop 1000 spectrophotometer. Results: Gender identification was done by amplification of sex determining region on Y chromosome (SRY gene using real-time polymerase chain reaction and minimal amount of DNA (in pico grams with 100% sensitivity and 73.3% specificity, i.e., all male samples showed positive results and out of 15 female samples 4 showed false positive results, i.e wrongly identified as males. Conclusion: With this study, we conclude that PCR is a valuable and sensitive procedure where minute contamination may cause alteration in the result, i.e, 4 females showed false positive result. Minute amount of DNA in picograms, which was collected at different intervals is enough for amplification of SRY gene and tooth brush can be used as one of the very valuable sources of gender identification.

  8. Role of hydrogen bonding in solubility of poly(N-isopropylacrylamide) brushes in sodium halide solutions

    Science.gov (United States)

    Xin-Jun, Zhao; Zhi-Fu, Gao

    2016-07-01

    By employing molecular theory, we systematically investigate the shift of solubility of poly(N-isopropylacrylamide) (PNIPAM) brushes in sodium halide solutions. After considering PNIPAM–water hydrogen bonds, water–anion hydrogen bonds, and PNIPAM–anion bonds and their explicit coupling to the PNIPAM conformations, we find that increasing temperature lowers the solubility of PNIPAM, and results in a collapse of the layer at high enough temperatures. The combination of the three types of bonds would yield a decrease in the solubility of PNIPAM following the Hofmeister series: NaCl>NaBr>NaI. PNIPAM–water hydrogen bonds are affected by water–anion hydrogen bonds and PNIPAM–anion bonds. The coupling of polymer conformations and the competition among the three types of bonds are essential for describing correctly a decrease in the solubility of PNIPAM brushes, which is determined by the free energy associated with the formation of the three types of bonds. Our results agree well with the experimental observations, and would be very important for understanding the shift of the lower critical solution temperature of PNIPAM brushes following the Hofmeister series. Project supported by the National Natural Science Foundation of China (Grant Nos. 21264016, 11464047, and 21364016) and the Joint Funds of Xinjiang Natural Science Foundation, China (Grant No. 2015211C298).

  9. Tea stains-inspired initiator primer for surface grafting of antifouling and antimicrobial polymer brush coatings.

    Science.gov (United States)

    Pranantyo, Dicky; Xu, Li Qun; Neoh, Koon-Gee; Kang, En-Tang; Ng, Ying Xian; Teo, Serena Lay-Ming

    2015-03-01

    Inspired by tea stains, plant polyphenolic tannic acid (TA) was beneficially employed as the primer anchor for functional polymer brushes. The brominated TA (TABr) initiator primer was synthesized by partial modification of TA with alkyl bromide functionalities. TABr with trihydroxyphenyl moieties can readily anchor on a wide range of substrates, including metal, metal oxide, polymer, glass, and silicon. Concomitantly, the alkyl bromide terminals serve as initiation sites for atom transfer radical polymerization (ATRP). Cationic [2-(methacryloyloxy)ethyl]trimethylammonium chloride (META) and zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC) and N-(3-sulfopropyl)-N-(methacryloxyethyl)-N,N-dimethylammonium betaine (SBMA) were graft-polymerized from the TABr-anchored stainless steel (SS) surface. The cationic polymer brushes on the modified surfaces are bactericidal, while the zwitterionic coatings exhibit resistance against bacterial adhesion. In addition, microalgal attachment (microfouling) and barnacle cyprid settlement (macrofouling) on the functional polymer-grafted surfaces were significantly reduced, in comparison to the pristine SS surface. Thus, the bifunctional TABr initiator primer provides a unique surface anchor for the preparation of functional polymer brushes for inhibiting both microfouling and macrofouling. PMID:25650890

  10. Calcium uptake by brush-border and basolateral membrane vesicles in chick duodenum

    International Nuclear Information System (INIS)

    Calcium uptake was compared between duodenal brush-border membrane vesicles (BBMV) and basolateral membrane vesicles (BLMV) isolated from vitamin D-deficient chicks and those injected with 625 ng of 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25(OH)2D3]. The uptake by BBMV in the 1 alpha,25-(OH)2D3-treated birds attained a maximum (280% of the control) at 12 h and was maintained at an elevated level (210%) at 24 h after the injection of the vitamin. In contrast, ATP-dependent calcium uptake by BLMV reached a maximum (185% of the control) at 6 h and decreased to the control level at 24 h. The kinetic analysis revealed that 1 alpha,25(OH)2D3 increased Vmax values without any changes in apparent Km values in both BBMV and BLMV. The activity of ATP-dependent calcium uptake was localized exclusively in the basolateral membrane, and the activity was inhibited by vanadate (IC50, 1 microM), but not by oligomycin, theophylline, calmodulin, trifluoperazine, or calbindin D28K. These results indicate that calcium transport through both the brush-border and basolateral membranes is involved in the 1 alpha,25(OH)2D3-dependent intestinal calcium absorption. The initiation of calcium absorption by 1 alpha,25(OH)2D3 appears to be due to an increase in the rate of calcium efflux at the basolateral membrane rather than the rate at the brush-border membrane

  11. Toward Infection-Resistant Surfaces: Achieving High Antimicrobial Peptide Potency by Modulating the Functionality of Polymer Brush and Peptide.

    Science.gov (United States)

    Yu, Kai; Lo, Joey C Y; Mei, Yan; Haney, Evan F; Siren, Erika; Kalathottukaren, Manu Thomas; Hancock, Robert E W; Lange, Dirk; Kizhakkedathu, Jayachandran N

    2015-12-30

    Bacterial infection associated with indwelling medical devices and implants is a major clinical issue, and the prevention or treatment of such infections is challenging. Antimicrobial coatings offer a significant step toward addressing this important clinical problem. Antimicrobial coatings based on tethered antimicrobial peptides (AMPs) on hydrophilic polymer brushes have been shown to be one of the most promising strategies to avoid bacterial colonization and have demonstrated broad spectrum activity. Optimal combinations of the functionality of the polymer-brush-tethered AMPs are essential to maintaining long-term AMP activity on the surface. However, there is limited knowledge currently available on this topic. Here we report the development of potent antimicrobial coatings on implant surfaces by elucidating the roles of polymer brush chemistry and peptide structure on the overall antimicrobial activity of the coatings. We screened several combinations of polymer brush coatings and AMPs constructed on nanoparticles, titanium surfaces, and quartz slides on their antimicrobial activity and bacterial adhesion against Gram-positive and Gram-negative bacteria. Highly efficient killing of planktonic bacteria by the antimicrobial coatings on nanoparticle surfaces, as well as potent killing of adhered bacteria in the case of coatings on titanium surfaces, was observed. Remarkably, the antimicrobial activity of AMP-conjugated brush coatings demonstrated a clear dependence on the polymer brush chemistry and peptide structure, and optimization of these parameters is critical to achieving infection-resistant surfaces. By analyzing the interaction of polymer-brush-tethered AMPs with model lipid membranes using circular dichroism spectroscopy, we determined that the polymer brush chemistry has an influence on the extent of secondary structure change of tethered peptides before and after interaction with biomembranes. The peptide structure also has an influence on the density

  12. Synthesis of novel glycopolymer brushes via a combination of RAFT-mediated polymerisation and ATRP

    Directory of Open Access Journals (Sweden)

    Eric T.A. van den Dungen

    2011-03-01

    Full Text Available Glycopolymers (synthetic sugar-containing polymers have become increasingly attractive to polymer chemists because of their role as biomimetic analogues and their potential for commercial applications. Glycopolymers of different structures confer high hydrophilicity and water solubility and can therefore be used for specialised applications, such as artificial materials for a number of biological, pharmaceutical and biomedical uses. The synthesis and characterisation of a series of novel glycopolymer brushes, namely poly(2-(2-bromoisobutyryloxy ethyl methacrylate-g-poly(methyl 6-O-methacryloyl-α-D-glucoside (P(BIEM-g-P(6-O-MMAGIc, poly(2-(2-bromoisobutyryloxy ethyl methacrylate-co-methyl methacrylate-g-poly(methyl 6-O-methacryloyl-α-D-glucoside P(BIEM-co-MMA-g-P(6-O-MMAGIc, poly(2-(2-bromoisobutyryloxy ethyl methacrylate-b-methyl methacrylate-g-poly(methyl 6-O-methacryloyl-α-D-glucoside P(BIEM-b-MMA-g-P(6-O-MMAGIc and poly(4-vinylbenzyl chloride-alt-maleic anhydride-g-poly(methyl 6-O-methacryloyl-α-D-glucoside (P(Sd-alt-MAnh-g-P(6-O-MMAGIc are described in this paper. Reversible addition-fragmentation chain transfer (RAFT-mediated polymerisation was used to synthesise four well-defined atom transfer radical polymerisation (ATRP macroinitiators (the backbone of the glycopolymer brushes. These ATRP macroinitiators were subsequently used in the ‘grafting from’ approach (in which side chains are grown from the backbone to prepare high molar mass and low polydispersity index glycopolymer brushes with different grafting densities along the backbone. The number average molar mass of the glycopolymer brushes was determined using size exclusion chromatography with a multi-angle laser light

  13. Brush-Coated Nanoparticle Polymer Thin Films: structure-mechanical-optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Green, Peter F. [Materials Science and Engineering

    2015-01-13

    understanding of physical phenomena associated with the structure of PNC systems and the glass transition and dynamics [7-11], including surface dynamics [12, 13]; designed PNCs to understand the connection between structure and specific optical responses of the material [14, 15]; electrorheological phenomena [16-18]; coarsening/aggregation phenomena [19, 20]; directed assembly [21] and elastic mechanical properties of thin supported films [22]. We established procedures to design and control the spatial distribution of gold nanoparticles (Au-NP), onto which polystyrene (PS) chains were end-grafted, within thin film PS hosts.[1-3] We explained how enthalpic and entropic interactions between the grafted layers and the polymer host chains, the nanoparticle (NP) sizes and shapes determine the spatial distribution of NPs within the host (i.e.: the morphology). In brief, the chemistries of the grafted chains and the polymer hosts, the degrees of polymerization of grafted and host chains (N and P, respectively), and the surface grafting densities Σ influence the thermodynamic interactions. Thin films are unique: the external interfaces (substrate and free surface) profoundly influence the spatial distribution of NPs within the PNC. For example, thin films are thermodynamically less stable than their bulk analogs due to the preferential attraction between the brush-coated nanoparticles and the external interfaces (i.e.: the free surface/polymer interface and the polymer/substrate interface). We investigated the organization of the brush-coated nanoparticles within a host composed on block copolymer micelles in a homopolymer [4, 5]. Block copolymers, composed of a polymer of type A that is bonded covalently to another polymer of type B (A-b-B) are known to form micelles within homopolymers A or B. A micelle is composed of an inner core of the A component of the copolymer and an outer corona of the B-component, that resides within homopolymer B, which serves as the host. If the host is

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-12-01

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

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

    Directory of Open Access Journals (Sweden)

    E Michael Danielsen

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

  16. Potential Hydrological Responses, and Carbon and Nitrogen Pools of a Two Distinct Watersheds to Rainfall and Brush Management

    Science.gov (United States)

    Ray, R. L.; Fares, A.; Awal, R.; Johnson, A. B.

    2014-12-01

    Investigating the effects of brush management on hydrologic fluxes, in the parts of the Texas where brush is a dominant component of the landscape is essential for the State of Texas's water management strategy and planning. The main goal of this study is to test the performance of brush management as an effective approach for protecting soil quality (carbon and nitrogen pools), and water resources management and planning. Specifically, this work reports on the potential i) hydrological response and ii) carbon and nitrogen pools of two watersheds, one in Colorado River Basin (arid) and the second one in Neches River Basin (humid), to brush management (uniform thinning vs. clear cutting) simulated using Regional Hydro-ecological Simulation System (RHESSys) model and site specific input data. The selected watersheds have similar potential evapotranspiration level, but their average elevations are 600 m and 250 m for the arid and humid watersheds, respectively. Results are showing that light thinning alone may not be enough to significantly impact water yield and soil quality. They further indicate that the streamflow response to brush reduction is a non-linear positive response.

  17. Engineering of spin injection and spin transport in organic spin valves using π-conjugated polymer brushes

    Science.gov (United States)

    Geng, Rugang; Roy, Anandi; Subedi, Ram; Locklin, Jason; Nguyen, Tho; Zhao, Wenbo; Li, Xiaoguang

    Charge transport in amorphous organic semiconductors is governed by carriers hopping between localized states with small spin diffusion length. Furthermore, the spin interfacial resistance of organic spin valves (OSVs) is poorly controlled resulting in controversial reports of the magnetoresistance response. Here, we used surface initiated Kumada transfer polycondensation to covalently graft π-conjugated poly(3-methylthiophene) brushes from the La0.67Sr0.33MnO3 (LSMO) bottom electrode. The covalent attachment along with the brush morphology allows for more control over the LSMO/brush interfacial resistance and large spacer mobility. Remarkably, with 15 nm brush spacer layer, we observed an optimum magnetoresistance (MR) effect of 70% at cryogenic temperatures and a MR of 2.7% at 280K. The temperature dependence of the MR is nearly an order of magnitude weaker than that found in control OSVs made from spin-coated poly(3-hexylthiophene). Using a variety of different brush layer thicknesses, the thickness dependent MR at 20K was investigated. A spin diffusion length of 20 nm at 5 mV junction voltage rapidly increases to 55 nm at -280 mV. We acknowledge NSF (CHE 1412714 and DMR 0953112) (J.L.), the UGA start-up funds and Faculty Research Grant (T.N.), NSFC and NBRPC (2012CB922003 and 2015CB921201, X.G.L.) for funding this work.

  18. Phase behaviour of two-component bottle-brush polymers with flexible backbones under poor solvent conditions

    International Nuclear Information System (INIS)

    The phase behaviour of two-component bottle-brush polymers with fully flexible backbones under poor solvent conditions is studied via molecular-dynamics simulations, using a coarse-grained bead-spring model and side chains of up to N = 40 effective monomers. We consider a symmetric model where side chains of type A and B are grafted alternately onto a flexible backbone. The aim of this study is to explore the phase behaviour of two-component bottle-brushes depending on parameters, such as as the grafting density σ, the backbone length Nb, the side-chain length N, and the temperature T. Based on a cluster analysis, we identify for our range of parameters the regimes of fully phase separated systems, i.e., A-type side chains form one cluster and B-type chains another, while the interface that separates these two clusters contains the backbone monomers. We find that pearl-necklace or Janus-like structures, which normally occur for bottle-brush polymers with rigid backbones under poor solvent conditions, are fully attributed to the backbone rigidity, and, therefore, such structures are unlikely in the case of bottle brushes with fully flexible backbones. Also, a comparative discussion with earlier work on the phase behaviour of single-component bottle-brush polymers with flexible backbones is performed. (paper)

  19. Changes in the permeability and morphology of dentine surfaces after brushing with a Thai herbal toothpaste: A preliminary study

    Science.gov (United States)

    Vajrabhaya, La-ongthong; Korsuwannawong, Suwanna; Harnirattisai, Choltacha; Teinchai, Chayada

    2016-01-01

    Objectives: The aim of this study was to evaluate dentine permeability after brushing with Twin Lotus®, Thai herbal toothpaste by comparing with Sensodyne Rapid Relief®, a commercial desensitizing toothpaste, and also after artificial saliva (AS) immersion or citric acid challenge. Materials and Methods: Dentine discs from human mandibular third molars were divided into three groups (n = 20) and brushed with either experimental toothpaste or water (control) for 2 min with an automated toothbrush. Then, 10 discs were immersed in AS, and the other 10 discs were immersed in 6% citric acid to simulate the conditions of the oral environment. The dentine permeability of each specimen was measured before brushing and after each treatment using a fluid filtration system. Morphological changes in the dentine were observed using scanning electron microscopy (SEM). Results: Both toothpastes significantly reduced dentine permeability, and a crystalline precipitate was observed on the dentine surface under SEM observation. No significant difference was found between the two toothpaste groups with regard to dentine permeability after brushing and AS or acid immersion. Conclusions: The dentine permeability reduction caused by the two toothpastes did not differ after brushing or after AS or citric acid immersion. PMID:27095904

  20. Artificial cilia as autonomous nanoactuators: Design of a gradient self-oscillating polymer brush with controlled unidirectional motion.

    Science.gov (United States)

    Masuda, Tsukuru; Akimoto, Aya Mizutani; Nagase, Kenichi; Okano, Teruo; Yoshida, Ryo

    2016-08-01

    A gradient self-oscillating polymer brush surface with ordered, autonomous, and unidirectional ciliary motion has been designed. The self-oscillating polymer is a random copolymer composed of N-isopropylacrylamide and ruthenium tris(2,2'-bipyridine) [Ru(bpy)3], which acts as a catalyst for an oscillating chemical reaction, the Belousov-Zhabotinsky reaction. The target polymer brush surface was designed to have a thickness gradient by using sacrificial-anode atom transfer radical polymerization. The gradient structure of the polymer brush was confirmed by x-ray photoelectron spectroscopy, atomic force microscopy, and ultraviolet-visible spectroscopy. These analyses revealed that the thickness of the polymer brush was in the range of several tens of nanometers, and the amount of Ru(bpy)3 increased as the thickness increased. The gradient polymer brush induced a unidirectional propagation of the chemical wave from the region with small Ru(bpy)3 amounts to the region with large Ru(bpy)3 amounts. This spatiotemporal control of the ciliary motion would be useful in potential applications to functional surface such as autonomous mass transport systems. PMID:27602405

  1. Novel lubricated surface of titanium alloy based on porous structure and hydrophilic polymer brushes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Kun; Xiong, Dangsheng, E-mail: xiongds@163.com; Niu, Yuxiang

    2014-10-30

    Graphical abstract: - Highlights: • Lubricated Ti6Al4V was fabricated by anodic oxidation and hydrophilic polymer grafting. • Surface composition and tribological properties were estimated. • Proper surface micropores formed at optimum voltage of 100 V. • Combined effect of porous structure and polymer brushes decreased friction coefficient and wear. • Hydrated lubricating layer and hydrodynamic lubrication contributed to lubricated surface. - Abstract: On the purpose of improving the tribological properties of titanium alloy through mimicking natural articular cartilage, porous structure was prepared on the surface of Ti6Al4V alloy by anodic oxidation method, and then hydrophilic polymer brushes were grafted onto its surface. Surface morphology of porous oxidized film was investigated by metalloscope and scanning electron microscope (SEM). The composition and structure of modified surface were characterized by Fourier-transform infrared spectroscopy with attenuated total reflection (FTIR/ATR), and the wettability was also evaluated. Friction and wear properties of modified alloys sliding against ultra-high molecular weight polyethylene (UHMWPE) were tested by a pin-on-disc tribometer in physiological saline. The results showed that, the optimum porous structure treated by anodic oxidation formed when the voltage reached as high as 100 V. Hydrophilic monomers [Acrylic acid (AA) and 3-dimethyl-(3-(N-methacrylamido) propyl) ammonium propane sulfonate (DMMPPS)] were successfully grafted onto porous Ti6Al4V surface to form polymer brushes by UV radiation. The change of contact angle showed that wettability of modified Ti6Al4V was improved significantly. The friction coefficient of modified Ti6Al4V was much lower and more stable than untreated ones. The lowest friction coefficient was obtained when the sample was anodized at 100 V and grafted with DMMPPS, and the value was 0.132. The wear of modified samples was also obviously improved.

  2. Non-thermal atmospheric plasma brush induces HEMA grafting onto dentin collagen

    Science.gov (United States)

    Chen, Mingsheng; Zhang, Ying; Dusevich, Vladimir; Liu, Yi; Yu, Qingsong; Wang, Yong

    2014-01-01

    Objective Non-thermal atmospheric plasma (NTAP) brush has been regarded as a promising technique to enhance dental interfacial bonding. However, the principal enhancement mechanisms have not been well identified. In this study, the effect of non-thermal plasmas on grafting of HEMA, a typical dental monomer, onto dentin collagen thin films was investigated. Methods Human dentin was sectioned into 10-um-thick films. After total demineralization in 0.5 M EDTA solution for 30 min, the dentin collagen films were water-rinsed, air-dried, treated with 35 wt% HEMA aqueous solution. The films were then subject to plasma-exposure under a NTAP brush with different time (1–8 min) / input power (5–15 w). For comparison, the dentin collagen films were also treated with the above HEMA solution containing photo-initiators, then subject to light-curing. After plasma-exposure or light-curing, the HEMA-collagen films were rinsed in deionized water, and then examined by FTIR spectroscopy and TEM. Results The FITR results indicated that plasma-exposure could induce significant HEMA grafting onto dentin collagen thin films. In contrast, light-curing led to no detectable interaction of HEMA with dentin collagen. Quantitative IR spectral analysis (i.e., 1720/3075 or 749/3075, HEMA/collagen ratios) further suggested that the grafting efficacy of HEMA onto the plasma-exposed collagen thin films strongly depended on the treatment time and input power of plasmas. TEM results indicated that plasma treatment did not alter collagen’s banding structure. Significance The current study provides deeper insight into the mechanism of dental adhesion enhancement induced by non-thermal plasmas treatment. The NTAP brush could be a promising method to create chemical bond between resin monomers and dentin collagen. PMID:25458523

  3. Monte Carlo simulations of the static friction between two grafted polymer brushes.

    Science.gov (United States)

    Mendonça, Ana C F; Goujon, Florent; Malfreyt, Patrice; Tildesley, Dominic J

    2016-02-17

    A configurational bias Monte Carlo method has been developed to study the static friction between grafted polymers immersed in a good solvent. Simple models using the soft quadratic potential from a dissipative particle dynamics study have been used to model polyzwitterionic brushes at physiological pressures (up to 7.5 MPa). Three models of decreasing rigidity have been used to model the friction between the brushes by calculating the tangential component of the pressure induced by a mismatch in the registry of the two grafting surfaces. The static friction coefficient can be calculated for three model systems and the slip between the layers occurs at a much lower values of shear force for the more flexible polymer layer. A moderate increase in the flexibility of the chains reduces the friction coefficient by a factor of ca. 20. Tilting the layer directors of the brushes also increases the static friction between the layer when the top, tilted layer is displaced in the direction away from the tilt. Non-equilibrium dynamics techniques for the same model were performed using dissipative particle dynamics and the limiting extremes of the Stribeck curve corresponding to the boundary lubrication regime and the hydrodynamic lubrication regime were observed for these flat surfaces. As expected, μk is significantly lower than μs for the same system. The dynamical friction coefficients in the model are in good agreement with those observed in the experiment and the ratio of μk/μs of between 0.11 and 0.5 observed in the simulations is in reasonable agreement with the value of 0.5 normally observed for these seen for these systems. PMID:26847471

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

    Czech Academy of Sciences Publication Activity Database

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

    2007-01-01

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

  5. Prevention of dentine erosion by brushing with anti-erosive toothpastes

    OpenAIRE

    Aykut-Yetkiner, Arzu; Attin, Thomas; Wiegand, Annette

    2014-01-01

    OBJECTIVE This in vitro study aimed to investigate the preventive effect of brushing with anti-erosive toothpastes compared to a conventional fluoride toothpaste on dentine erosion. MATERIALS AND METHODS Bovine dentine specimens (n=12 per subgroup) were eroded in an artificial mouth (6 days, 6×30 s/day) using either citric acid (pH:2.5) or a hydrochloric acid/pepsin solution (pH:1.6), simulating extrinsic or intrinsic erosive conditions, respectively. In between, the specimens were rinsed ...

  6. EFFICACY OF THREE DENTURE BRUSHES ON BIOFILM REMOVAL FROM COMPLETE DENTURES

    OpenAIRE

    Roseana Aparecida Gomes Fermandes; Cláudia Helena Lovato - Silva; Helena de Freitas Oliveira Paranhos; Izabel Yoko Ito

    2007-01-01

    The aim of this study was to compare the efficacy of three denture brushes (Bitufo-B; Medic Denture-MD; Colgate-C) on biofilm removal from upper and lower dentures using a specific dentifrice (Corega Brite). The correlation between biofilm levels on the internal and external surfaces of the upper and lower dentures was also evaluated. A microbiological assay was performed to assess the growth of colony-formed units (cfu) of Candida yeasts on denture surface. Thirty-three patients were enrolle...

  7. Effect of a chlorhexidine-containing brush-on gel on peri-implant mucositis

    DEFF Research Database (Denmark)

    Hallström, H; Lindgren, S; Twetman, S

    2016-01-01

    OBJECTIVE: The aim was to evaluate the effect of a chlorhexidine-containing brush-on gel when used as supplement to oral hygiene instructions and mechanical debridement, on peri-implant mucositis in adults. MATERIALS AND METHODS: The study group consisted of 38 adults (48-87 years.) with peri......-implant mucositis that were consecutively enrolled in three private clinics after informed consent. The study employed a double-blind controlled design with two parallel arms. After baseline registrations, oral hygiene reinforcement and mechanical debridement, the patients were randomly allocated to either a test...

  8. Experimental investigation of the flow near the ram element in the brush turbine

    Directory of Open Access Journals (Sweden)

    Schmirler M.

    2015-01-01

    Full Text Available The paper focuses on the investigating of the parameters of the fluid flow around the brush turbine ram element. The flow field was evaluated qualitatively by observing changes in density using a Schlieren method. It was also evaluated the influence of the element geometry on the total aerodynamic force of the element. The aerodynamic force was measured directly using a special aerodynamic balance. The aim of the project was to find the simplest element geometry with a maximum force effect and achieve an increase in overall efficiency and reduce the manufacturing costs.

  9. Tooth brushing skills for the children aged 3-11 years

    OpenAIRE

    Das U; Singhal P

    2009-01-01

    Objectives: The objective of this study was to evaluate tooth brushing management and ability of children in relation to age and gender. Materials and Methods: The study population consisted of 45 children, who attended Department of Pedodontics and Preventive Dentistry at V.S Dental College and Hospital Bangalore. Children were divided into three groups according to age: Group I: 3-5 years, Group II: 6-8 years, and Group III: 9-11 years. Each child selected his/her favorite toothbrush and...

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

    DEFF Research Database (Denmark)

    Danielsen, E Michael; Hansen, Gert H

    2003-01-01

    -linked and transmembrane digestive enzymes, most likely as an economizing effort to secure and prolong their digestive capability at the microvillar surface. However, in addition to microvilli, the brush border surface also consists of membrane invaginations between adjacent microvilli, which are the only part...... of the apical surface sterically accessible for membrane fusion/budding events. Many of these invaginations appear as pleiomorphic, deep apical tubules that extend up to 0.5-1 microm into the underlying terminal web region. Their sensitivity to methyl-beta-cyclodextrin suggests them to contain cholesterol...

  11. Ultrathin, freestanding, stimuli-responsive, porous membranes from polymer hydrogel-brushes

    Science.gov (United States)

    Kang, Chengjun; Ramakrishna, Shivaprakash N.; Nelson, Adrienne; Cremmel, Clement V. M.; Vom Stein, Helena; Spencer, Nicholas D.; Isa, Lucio; Benetti, Edmondo M.

    2015-07-01

    The fabrication of freestanding, sub-100 nm-thick, pH-responsive hydrogel membranes with controlled nano-morphology, based on modified poly(hydroxyethyl methacrylate) (PHEMA) is presented. Polymer hydrogel-brush films were first synthesized by surface-initiated atom transfer radical polymerization (SI-ATRP) and subsequently detached from silicon substrates by UV-induced photo-cleavage of a specially designed linker within the initiator groups. The detachment was also assisted by pH-induced osmotic forces generated within the films in the swollen state. The mechanical properties and morphology of the freestanding films were studied by atomic force microscopy (AFM). Inclusion of nanopores of controlled diameter was accomplished by performing SI-ATRP from initiator-coated surfaces that had previously been patterned with polystyrene nanoparticles. Assembly parameters and particle sizes could be varied, in order to fabricate nanoporous hydrogel-brush membranes with tunable pore coverage and characteristics. Additionally, due to the presence of weak polyacid functions within the hydrogel, the membranes exhibited pH-dependent thickness in water and reversible opening/closing of the pores.The fabrication of freestanding, sub-100 nm-thick, pH-responsive hydrogel membranes with controlled nano-morphology, based on modified poly(hydroxyethyl methacrylate) (PHEMA) is presented. Polymer hydrogel-brush films were first synthesized by surface-initiated atom transfer radical polymerization (SI-ATRP) and subsequently detached from silicon substrates by UV-induced photo-cleavage of a specially designed linker within the initiator groups. The detachment was also assisted by pH-induced osmotic forces generated within the films in the swollen state. The mechanical properties and morphology of the freestanding films were studied by atomic force microscopy (AFM). Inclusion of nanopores of controlled diameter was accomplished by performing SI-ATRP from initiator-coated surfaces that had

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

    Directory of Open Access Journals (Sweden)

    Katyal R

    2002-01-01

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

  13. Neutron reflectivity measurement of polymer monolayer and brush at the air/water interface

    International Nuclear Information System (INIS)

    We have been studied on amphiphilic polymer monolayer structure at the air/water interface by X-ray and neutron reflectometry. By complemently use of X-ray and neutron reflectometry, we have found (1) the existence of carpet layer in ionic polymer brush in monolayer system and (2) characteristic structural change in polymer/subphase interface. Furthermore, interesting experiment on small ion distribution was carried out by NR with contrast variation method. With our experimental examples, characteristic points in the neutron reflectivity measurement at the air/water interface and further possibility in this research area are discussed. (author)

  14. Caries-preventive effectiveness of fluoride varnish as adjunct to oral health promotion and supervised tooth brushing in preschool children

    DEFF Research Database (Denmark)

    Agouropoulos, A; Twetman, S; Pandis, N;

    2014-01-01

    OBJECTIVES: To evaluate the effect of biannual fluoride varnish applications in preschool children as an adjunct to school-based oral health promotion and supervised tooth brushing with 1000ppm fluoride toothpaste. METHODS: 424 preschool children, 2-5 year of age, from 10 different pre schools...... in Athens were invited to this double-blind randomized controlled trial and 328 children completed the 2-year programme. All children received oral health education with hygiene instructions twice yearly and attended supervised tooth brushing once daily. The test group was treated with fluoride varnish (0...... by the varnish treatments. CONCLUSIONS: Under the present conditions, biannual fluoride varnish applications in preschool children did not show significant caries-preventive benefits when provided as an adjunct to school-based supervised tooth brushing with 1000ppm fluoride toothpaste. CLINICAL SIGNIFICANCE...

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

    DEFF Research Database (Denmark)

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

    2003-01-01

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

  16. Effect of polymer brushes on the Self Assembly of 3D Poly(Styrene-Methylmethacrylate) thin films

    Science.gov (United States)

    Lwoya, Baraka; Albert, Julie

    2015-03-01

    It would be instrumental to understand the self-assembly capabilities of polymers especially given their industrial capabilities of templating and membrane application .The ability of block copolymers to self assemble into different morphologies is determined by several factor including type of polymer blocks, volume fraction, substrate preference to a polymer and chain architecture . In this paper Poly(Styrene-Methylmethacrylate) (PS-PMMA) was chosen was chosen to further understand the effect polymer brushes on the substrate had on the self assembly of 3D structured PS-PMMA spin coated thin films (30-150 nm). The polymer brushes were grown using surface initiated atomic transfer radical polymerization (SI-ATRP) with the optimal chain length being confirmed by gel permeation chromatography. By using ellipsometer and contact angle measurement the uniformity of the polymer brushes are characterized, while the morphology of the spin coated thin films after thermal annealing would be characterized using atomic force microscopy (AFM).

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

    DEFF Research Database (Denmark)

    Danielsen, E Michael; Hansen, Gert H

    2013-01-01

    multiple deleterious agents present in the gut lumen, such as bile salts, digestive enzymes of the pancreas, and a plethora of pathogens. In the present work, we studied the constitutive endocytosis from the brush border of cultured jejunal explants of the pig, and the results indicate that this process...... functions to enrich the contents of lipid raft components in the brush border. The lipophilic fluorescent marker FM, taken up into early endosomes in the terminal web region (TWEEs), was absent from detergent resistant membranes (DRMs), implying an association with non-raft membrane. Furthermore, neither...... major lipid raft-associated brush border enzymes nor glycolipids were detected by immunofluorescence microscopy in subapical punctae resembling TWEEs. Finally, two model raft lipids, BODIPY-lactosylceramide and BODIPY-GM1, were not endocytosed except when cholera toxin subunit B (CTB) was present. In...

  18. Structural properties of polymer-brush-grafted gold nanoparticles at the oil-water interface: insights from coarse-grained simulations.

    Science.gov (United States)

    Quan, Xuebo; Peng, ChunWang; Dong, Jiaqi; Zhou, Jian

    2016-04-14

    In this work, the structural properties of amphiphilic polymer-brush-grafted gold nanoparticles (AuNPs) at the oil-water interface were investigated by coarse-grained simulations. The effects of grafting architecture (diblock, mixed and Janus brush-grafted AuNPs) and hydrophilicity of polymer brushes are discussed. Simulation results indicate that functionalized AuNPs present abundant morphologies including typical core-shell, Janus-type, jellyfish-like, etc., in a water or oil-water solvent environment. It is found that hydrophobic/weak hydrophilic polymer-brush-grafted AuNPs have better phase transfer performance, especially for AuNPs modified with hydrophobic chains as outer blocks and weak hydrophilic chains as inner blocks. This kind of AuNP can cross the interface region and move into the oil phase completely. For hydrophobic/strong hydrophilic polymer-brush-grafted AuNPs, they are trapped in the interface region instead of moving into any phase. The mechanism of phase transfer is ascribed to the flexibility and mobility of outer blocks. Besides, we study the desorption energy by PMF analysis. The results demonstrate that Janus brush-grafted AuNPs show the highest interfacial stability and activity, which can be further strengthened by increasing the hydrophilicity of grafted polymer brushes. This work will promote the industrial applications of polymer-brush-grafted NPs such as phase transfer catalysis and Pickering emulsion catalysis. PMID:26954721

  19. Research on the Working Mechanism and Virtual Design for Cleaning Element in Brush Shape of the Sugarcane Harvester

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The cleaning element is the key part to the small w ho le-stall sugarcane harvester, which is suitable to the highland. And it is the bottleneck of the design of the small sugarcane harvester. The working mechanism of centrifugal cleaning method of the cleaning element in brush shape is based on the high speed rotating cleaning element that push, scrub, and strike the sta lk to separate the leaves from the sugarcane. The paper elaborated the worki ng mechanism of cleaning element in brush shape of the ...

  20. Evidence for vertical phase separation in densely grafted, high-molecular-weight poly(N-isopropylacrylamide) brushes in water

    International Nuclear Information System (INIS)

    The detailed conformational change of poly(N-isopropylacrylamide) (PNIPAM) brushes at high grafting density in D2O was investigated as a function of temperature using neutron reflection. PNIPAM chains were grafted at high surface density from gold and silicon oxide surfaces by atom transfer radical polymerization. Whereas single layer profiles were observed for temperatures below and above the transition region, bilayer profiles were observed for a narrow range of temperatures near the transition. This nonmonotonic change in the concentration profile with temperature is discussed in the context of theoretical models of vertical phase separation within a brush

  1. Effect of Sugar-Free Gum in Addition to Tooth Brushing on Dental Plaque and Interdental Debris

    OpenAIRE

    Kakodkar, Pradnya; Mulay, Soniya

    2010-01-01

    Background: Chewing-gum may serve as an effective oral hygiene device when brushing may not be possible. The aim of the present study was to evaluate the effect of chewing sugar-free gum twice a day after meals in addition to tooth brushing on dental plaque and interdental debris. Methods Twenty four (12 males and 12 females aged 20-21 years) healthy third-year dental students participated in the study. It was a prospective single blind and non-randomized before and after study. The control g...

  2. Effect of sugar-free gum in addition to tooth brushing on dental plaque and interdental debris

    OpenAIRE

    Pradnya Kakodkar; Soniya Mulay

    2010-01-01

    Background: Chewing-gum may serve as an effective oral hygiene device when brushing may not be possible. The aim of the present study was to evaluate the effect of chewing sugar-free gum twice a day after meals in addition to tooth brushing on dental plaque and interdental debris. Methods : Twenty four (12 males and 12 females aged 20-21 years) healthy third-year dental students participated in the study. It was a prospective single blind and non-randomized before and after study. The co...

  3. Novel lubricated surface of titanium alloy based on porous structure and hydrophilic polymer brushes

    Science.gov (United States)

    Wang, Kun; Xiong, Dangsheng; Niu, Yuxiang

    2014-10-01

    On the purpose of improving the tribological properties of titanium alloy through mimicking natural articular cartilage, porous structure was prepared on the surface of Ti6Al4V alloy by anodic oxidation method, and then hydrophilic polymer brushes were grafted onto its surface. Surface morphology of porous oxidized film was investigated by metalloscope and scanning electron microscope (SEM). The composition and structure of modified surface were characterized by Fourier-transform infrared spectroscopy with attenuated total reflection (FTIR/ATR), and the wettability was also evaluated. Friction and wear properties of modified alloys sliding against ultra-high molecular weight polyethylene (UHMWPE) were tested by a pin-on-disc tribometer in physiological saline. The results showed that, the optimum porous structure treated by anodic oxidation formed when the voltage reached as high as 100 V. Hydrophilic monomers [Acrylic acid (AA) and 3-dimethyl-(3-(N-methacrylamido) propyl) ammonium propane sulfonate (DMMPPS)] were successfully grafted onto porous Ti6Al4V surface to form polymer brushes by UV radiation. The change of contact angle showed that wettability of modified Ti6Al4V was improved significantly. The friction coefficient of modified Ti6Al4V was much lower and more stable than untreated ones. The lowest friction coefficient was obtained when the sample was anodized at 100 V and grafted with DMMPPS, and the value was 0.132. The wear of modified samples was also obviously improved.

  4. Block copolymer assembly on nanoscale patterns of polymer brushes formed by electrohydrodynamic jet printing.

    Science.gov (United States)

    Onses, M Serdar; Ramírez-Hernández, Abelardo; Hur, Su-Mi; Sutanto, Erick; Williamson, Lance; Alleyne, Andrew G; Nealey, Paul F; de Pablo, Juan J; Rogers, John A

    2014-07-22

    Fundamental understanding of the self-assembly of domains in block copolymers (BCPs) and capabilities in control of these processes are important for their use as nanoscale templates in various applications. This paper focuses on the self-assembly of spin-cast and printed poly(styrene-block-methyl methacrylate) BCPs on patterned surface wetting layers formed by electrohydrodynamic jet printing of random copolymer brushes. Here, end-grafted brushes that present groups of styrene and methyl methacrylate in geometries with nanoscale resolution deterministically define the morphologies of BCP nanostructures. The materials and methods can also be integrated with lithographically defined templates for directed self-assembly of BCPs at multiple length scales. The results provide not only engineering routes to controlled formation of complex patterns but also vehicles for experimental and simulation studies of the effects of chemical transitions on the processes of self-assembly. In particular, we show that the methodology developed here provides the means to explore exotic phenomena displayed by the wetting behavior of BCPs, where 3-D soft confinement, chain elasticity, interfacial energies, and substrate's surface energy cooperate to yield nonclassical wetting behavior. PMID:24882265

  5. Thermally Tunable Metallodielectric Photonic Crystals from Self-assembly of Brush Block Copolymers and Gold Nanoparticles

    Science.gov (United States)

    Song, Dongpo; Li, Cheng; Colella, Nicholas; Lu, Xuemin; Watkins, James

    2015-03-01

    Photonic crystals (PCs) based on the self-assembly of block copolymers (BCPs) are under intense investigations, providing new opportunities for simple fabrication of flexible photonic devices or coatings in an inexpensive and scalable way. The precise control and selective incorporation of inorganic nanoparticles (NPs) into specific domains of the microphase separated BCPs can be used to tune the optical constant of the target domains and create hybrid materials with unique optical properties. In this work, we demonstrate a simple strategy for rapid fabrication of well-ordered metallodielectric 1-D PCs using PS- b-PEO brush BCPs as the templates and H-bonding as the driving force for selective incorporation of phenol-coated gold nanoparticles (NPs) into PEO domains. By varying gold NP loading or molecular weight of the brush BCP, periodic layered metallodielectric structures with the domain spacing controlled from 120 nm to 261 nm were readily created resulting in reflection of light widely tunable from the visible to near IR regions (458-1010 nm). The control over size as well as the distribution of the gold NPs in the well-ordered structure was realized through simple thermal treatment, showing significant effects on the optical properties. This work was supported by the NSF Center for Hierarchical Manufacturing at the University of Massachusetts (CMMI-1025020).

  6. Synthesis and suspension rheology of titania nanoparticles grafted with zwitterionic polymer brushes.

    Science.gov (United States)

    Shao, Zhen; Yang, Youngjun; Lee, Hyunsuk; Kim, Jin Woong; Osuji, Chinedum O

    2012-11-15

    Titania nanoparticles were modified by free-radical graft polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) at the particle surface, resulting in the formation of a 1-2 nm thick polymer brush. The zwitterionic nature of the polymer layer suggests that the suspension stability is a delicate function of pH, as well as volume fraction, salt concentration and the presence of charged or un-charged additives which may act as depletants or to screen charge interactions in the system. In this context, we characterized the suspension rheology as a function of volume fraction, pH, ionic strength and the concentration of surfactants in the suspension. Near-neutral pH, the brush layer is effective in stabilizing particles against aggregation with Newtonian behavior observed for volume fractions approaching 14%. Flocculation of particles and an onset of shear-thinning behavior was observed on decreasing pH from near-neutral. Conversely, suspension stability was maintained on increasing pH from near-neutral. Likewise, flocculation could be quickly induced by the addition of salt and cationic surfactant in small amounts, but the suspensions displayed greater stability to anionic and non-ionic surfactant additives. These results have important implications for the successful formulation of complex fluids employing zwitterionic colloids. PMID:22909963

  7. Na+ and H+ transport in human jejunal brush-border membrane vesicles

    International Nuclear Information System (INIS)

    The authors have examined pH gradient-driven Na+ uptake and Na+-driven H+ transport in brush-border membrane vesicles prepared from jejunal tissue obtained from organ donors by measuring the influx of 22Na and the fluorescence quenching of acridine orange (AO). Vesicle preparation by either Ca2+ or Mg2+ precipitation showed no difference in 22Na uptake or AO fluorescence quenching and dissipation. An outward H+ gradient induced a Na+ uptake overshoot of threefold over equilibrium, whereas the absence of an H+ gradient did not produce an overshoot. The initial rate of pH-driven Na+ uptake in voltage-clamped vesicles was related to [Na+o]. Amiloride inhibited this uptake in voltage-clamped vesicles. Dissipation of AO fluorescence quench in vesicles with a preformed internal acid gradient was hastened by Na+o as well as voltage clamping in the absence of Na+. In vesicles without a pH gradient, internal Na+, as well as a diffusion potential in the absence of Na+, induced AO quenching. External Na+ and Li+, but not choline, acted to dissipate AO quenching induced by a diffusion potential, and the rate of dissipation was unaffected by the presence of Cl-. Li+ and NH+4, but not Cs+, K+, Rb+, or choline+, inhibited pH gradient-driven 22Na uptake. They conclude that human jejunal brush-border membrane vesicles contain conductive pathways for both Na+ and H+ and an Na+-H+ exchanger

  8. Thermally controlled permeation of ionic molecules through synthetic nanopores functionalized with amine-terminated polymer brushes

    Science.gov (United States)

    Nasir, Saima; Ali, Mubarak; Ensinger, Wolfgang

    2012-06-01

    We present temperature-dependent ionic transport through an array of nanopores (cylindrical and conical) and a single conical nanopore functionalized with amine-terminated poly(N-isopropylacrylamide) [PNIPAAM-NH2] brushes. For this purpose, nanopores are fabricated in heavy ion irradiated polyethylene terephthlate (PET) membranes by a controlled chemical track-etching technique, which leads to the generation of carboxyl (COOH) groups on the pore surface. End-functionalized polymer chains are immobilized onto the inner pore walls via a ‘grafting-to’ approach through the covalent linkage of surface COOH moieties with the terminal amine groups of the PNIPAAM molecules by using carbodiimide coupling chemistry. The success of the chemical modification reaction is corroborated by measuring the permeation flux of charged analytes across the multipore membranes in an aqueous solution, and for the case of single conical pore by measuring the current-voltage (I-V) characteristics, which are dictated by the electrostatic interaction of the charged pore surface with the mobile ions in an electrolyte solution. The effective nanopore diameter is tuned by manipulating the environmental temperature due to the swelling/shrinking behaviour of polymer brushes attached to the inner nanopore walls, leading to a decrease/increase in the ionic transport across the membrane. This process should permit the thermal gating and controlled release of ionic drug molecules through the nanopores modified with thermoresponsive polymer chains across the membrane.

  9. Thermally controlled permeation of ionic molecules through synthetic nanopores functionalized with amine-terminated polymer brushes

    International Nuclear Information System (INIS)

    We present temperature-dependent ionic transport through an array of nanopores (cylindrical and conical) and a single conical nanopore functionalized with amine-terminated poly(N-isopropylacrylamide) [PNIPAAM-NH2] brushes. For this purpose, nanopores are fabricated in heavy ion irradiated polyethylene terephthlate (PET) membranes by a controlled chemical track-etching technique, which leads to the generation of carboxyl (COOH) groups on the pore surface. End-functionalized polymer chains are immobilized onto the inner pore walls via a ‘grafting-to’ approach through the covalent linkage of surface COOH moieties with the terminal amine groups of the PNIPAAM molecules by using carbodiimide coupling chemistry. The success of the chemical modification reaction is corroborated by measuring the permeation flux of charged analytes across the multipore membranes in an aqueous solution, and for the case of single conical pore by measuring the current–voltage (I–V) characteristics, which are dictated by the electrostatic interaction of the charged pore surface with the mobile ions in an electrolyte solution. The effective nanopore diameter is tuned by manipulating the environmental temperature due to the swelling/shrinking behaviour of polymer brushes attached to the inner nanopore walls, leading to a decrease/increase in the ionic transport across the membrane. This process should permit the thermal gating and controlled release of ionic drug molecules through the nanopores modified with thermoresponsive polymer chains across the membrane. (paper)

  10. Penanganan Gingivitis dengan Metoda "Toothpick Brushing" (Laporan kasus pada wanita pengguna kontrasepsi oral

    Directory of Open Access Journals (Sweden)

    Armasastra Bahar

    2015-10-01

    Full Text Available Gingivitis sebagai salah satu kelainan jaringan penyangga gigi telah diketahui disebabkan karena kebersihan mulut yang tidak baik dan berkaitan dengan kebiasaan dan cara menyikat gigi yang tidak memadai. Di samping itu telah banyak pula laporan yang mengatakan bahwa terjadinya gingivitis juga berhubungan dengan peningkatan hormon kelamin steroid darah seperti pada kehamilan, menstruasi dan pada pengguna kontrasepsi hormonal.Dalam pemeriksaan yang dilakukan pada beberapa wanita pengguna kontrasepsi oral di Puskesmas Serpong ditemukan kelainan gingivitis.Pada penderita tersebut dilakukan pemeriksaan intraoral dan Occult Blood Test untuk memperkuat pemeriksaan apakah keadaan gingivitisnya memerlukan terapi lebih lanjut. Setelah dilakukan penambalan gigi yang merupakan keluhan utama penderita datang ke BKIA, dilakukan usaha untuk menanggulangi gingivitis yang ada berupa penerangan tentang faktor-faktor yang menjadi penyebab gingivitis dan instruksi cara menyikat gigi dengan metoda "Toothpick brushing". Evaluasi yang dilakukan pada minggu II dan III, memperlihatkan hasil yang baik, nilai PI, PBI dan OBT menurun dibandingkan dengan nilai awal yang telah dilakukan.Pada kunjungan pada minggu III dilakukan pembersihan karang gigi. Menyikat gigi dengan metoda "Toothpick brushing" memperlihatkan hasil yang baik dalam memperbaiki kelainan gingivitis.

  11. Bronchial brush biopsies for studies of epithelial inflammation in stable asthma and nonobstructive chronic bronchitis.

    Science.gov (United States)

    Riise, G C; Andersson, B; Ahlstedt, S; Enander, I; Söderberg, M; Löwhagen, O; Larsson, S

    1996-08-01

    Recently, bronchial brush biopsy (BBB) has been introduced as a complimentary method to bronchial forceps biopsy for the study of bronchial epithelial cells. We wanted to determine whether epithelial inflammatory cells in bronchial brush biopsies can reflect mucosal inflammation assessed indirectly by levels of cellular activation markers in bronchial lavage fluid. We studied 15 healthy controls, 11 asthmatics with regular steroid inhalation therapy, 13 asthmatics without steroids, and 10 smokers with nonobstructive chronic bronchitis. Differential counts of epithelial and inflammatory cells were made from the BBB material. Bronchial lavage levels of eosinophil cationic protein (ECP), myeloperoxidase (MPO), tryptase, hyaluronan and interleukin-8 (IL-8) were measured as indirect markers for inflammatory cell activation. We found an increased percentage of eosinophil granulocytes in the BBB from the steroid-untreated asthmatic patients (1.16%) in comparison to the other groups (0.11%, 0.09% and 0.02%, respectively; pairways disease. These changes appear to relate to the degree of inflammatory activity and disease severity in asthma. PMID:8866592

  12. Oil-Soluble Polymer Brush Grafted Nanoparticles as Effective Lubricant Additives for Friction and Wear Reduction.

    Science.gov (United States)

    Wright, Roger A E; Wang, Kewei; Qu, Jun; Zhao, Bin

    2016-07-18

    The development of high performance lubricants has been driven by increasingly growing industrial demands and environmental concerns. Herein, we demonstrate oil-soluble polymer brush-grafted inorganic nanoparticles (hairy NPs) as highly effective lubricant additives for friction and wear reduction. A series of oil-miscible poly(lauryl methacrylate) brush-grafted silica and titania NPs were synthesized by surface-initiated atom transfer radical polymerization. These hairy NPs showed exceptional stability in poly(alphaolefin) (PAO) base oil; no change in transparency was observed after being kept at -20, 22, and 100 °C for ≥55 days. High-contact stress ball-on-flat reciprocating sliding tribological tests at 100 °C showed that addition of 1 wt % of hairy NPs into PAO led to significant reductions in coefficient of friction (up to ≈40 %) and wear volume (up to ≈90 %). The excellent lubricating properties of hairy NPs were further elucidated by the characterization of the tribofilm formed on the flat. These hairy NPs represent a new type of lubricating oil additives with high efficiency in friction and wear reduction. PMID:27265613

  13. Thicker is better? Synthesis and evaluation of well-defined polymer brushes with controllable catalytic loadings.

    Science.gov (United States)

    Fernandes, Antony E; Dirani, Ali; d'Haese, Cécile; Deumer, Gladys; Guo, Weiming; Hensenne, Peter; Nahra, Fady; Laloyaux, Xavier; Haufroid, Vincent; Nysten, Bernard; Riant, Olivier; Jonas, Alain M

    2012-12-01

    Polymer brushes (PBs) have been used as supports for the immobilization of palladium complexes on silicon surfaces. The polymers were grown by surface-initiated atom-transfer radical polymerization (SI-ATRP) and postdecorated with dipyridylamine (dpa) ligands. The pendant dpa units were in turn complexed with [Pd(OAc)(2)] to afford hybrid catalytic surfaces. A series of catalytic samples of various thicknesses (ca. 20-160 nm) and associated palladium loadings (ca. 10-45 nmol  cm(-2)) were obtained by adjusting the SI-ATRP reaction time and characterized by ellipsometry, X-ray reflectivity, X-ray photoelectron spectroscopy, and inductively coupled plasma mass spectrometry (ICP-MS). ICP-MS revealed a near-linear relationship between thickness of the polymer brush and palladium content, which confirmed the robustness of the preparation and postmodification sequence presented herein, rendering possible the creation of functional architectures with predefined catalytic potential. The activities of the catalytic PBs were determined by systematically exploring a full range of substrate-to-catalyst ratios in a model palladium(0)-catalyzed reaction. Quantitative transformations were observed for loadings down to 0.03 mol % and a maximum turnover number (TON) of around 3500 was established for the system. Comparison of the catalytic performances evidenced a singular influence of the thickness on conversions and TONs. The limited recyclability of the hairy catalysts has been attributed to palladium leaching. PMID:23032959

  14. Reorganization of hydrogen bond network makes strong polyelectrolyte brushes pH-responsive

    Science.gov (United States)

    Wu, Bo; Wang, Xiaowen; Yang, Jun; Hua, Zan; Tian, Kangzhen; Kou, Ran; Zhang, Jian; Ye, Shuji; Luo, Yi; Craig, Vincent S. J.; Zhang, Guangzhao; Liu, Guangming

    2016-01-01

    Weak polyelectrolytes have found extensive practical applications owing to their rich pH-responsive properties. In contrast, strong polyelectrolytes have long been regarded as pH-insensitive based on the well-established fact that the average degree of charging of strong polyelectrolyte chains is independent of pH. The possible applications of strong polyelectrolytes in smart materials have, thus, been severely limited. However, we demonstrate that almost all important properties of strong polyelectrolyte brushes (SPBs), such as chain conformation, hydration, stiffness, surface wettability, lubricity, adhesion, and protein adsorption are sensitive to pH. The pH response originates from the reorganization of the interchain hydrogen bond network between the grafted chains, triggered by the pH-mediated adsorption-desorption equilibrium of hydronium or hydroxide with the brushes. The reorganization process is firmly identified by advanced sum-frequency generation vibrational spectroscopy. Our findings not only provide a new understanding of the fundamental properties of SPBs but also uncover an extensive family of building blocks for constructing pH-responsive materials.

  15. Characterization of stable brush-shaped large-volume plasma generated at ambient air

    International Nuclear Information System (INIS)

    A brush-shaped, large-volume plasma was generated at ambient pressure with a dc power supply and flowing argon gas, as well as a narrow outlet slit. Based on the V-I curve and emission profiles obtained in our experiment, the plasma shows some typical glow discharge characteristics. The electron density in the positive column close to the anode is about 1.4x1014cm-3 high, which is desirable for generating abundant amounts of reactive species in the plasma. Emission spectroscopy diagnosis indicates that many reactive species, such as excited argon atoms, excited oxygen atoms, excited nitrogen molecules, OH and C2 radicals, etc., generated within the plasma are distributed symmetrically and uniformly, which is preferable to some chemical reactions in practical applications. Spectral measurement also shows that the concentration of some excited argon atoms increases with the argon flow rate when the applied voltage is unvaried, while that of these excited argon atoms declines with the discharge current in the normal/subnormal glow discharge mode with the argon flow rate fixed. The plasma size is about 15 mm x 1 mm x 19 mm (L, W, H), when 38-W of discharge power is used. Such a laminar brush-shaped large-volume plasma device ensures not only efficient utilization of the plasma gas, but also effective processing of objects with large volume and complicated structure that are susceptible to high temperatures.

  16. The Impact of Dietary and Tooth-Brushing Habits to Dental Caries of Special School Children with Disability

    Science.gov (United States)

    Liu, Hsiu-Yueh; Chen, Chun-Chih; Hu, Wen-Chia; Tang, Ru-Ching; Chen, Cheng-Chin; Tsai, Chi-Cheng; Huang, Shun-Te

    2010-01-01

    The daily oral activities may severely influence oral health of children with disabilities. In this survey, we analyzed the impact of dietary and tooth-brushing habits to dental caries in special school children with disabilities. This cross-sectional survey investigated 535 special school children with disabilities aged 6-12 years, 60.93% males,…

  17. Poster: Brush, Lasso, or Magic Wand? Picking the Right Tool for Large-Scale Multiple Object Selection Tasks

    DEFF Research Database (Denmark)

    Stenholt, Rasmus; Madsen, Claus B.

    2012-01-01

    , a spherical brush and a box-shaped lasso for multiple object selection (MOS), and compare them to a new MOS technique, which we have named the magic wand. This new technique automates a lot the work, which the user would normally have to do manually. The comparison is made through a user study...

  18. Potential fatigue strength improvement of AA 5083-H111 notched parts by wire brush hammering: Experimental analysis and numerical simulation

    International Nuclear Information System (INIS)

    Highlights: • Wire brush hammering increases by 20% the AA 5083-H111 notched parts fatigue limit. • Improvement of fatigue strength is related to the fatigue cracks nucleation. • Fatigue strength prediction accounts for wire brush hammering effects. - Abstract: The effects of milling as machining process and a post-machining treatment by wire-brush hammering, on the near surface layer characteristics of AA 5083-H111 were investigated. Surface texture, work-hardening and residual stress profiles were determined by roughness measurement, scanning electron microscope (SEM) examinations, microhardness and X-ray diffraction (XRD) measurements. The effects of surface preparation on the fatigue strength were assessed by bending fatigue tests performed on notched samples for two loading stress ratios R0.1 and R0.5. It is found that the bending fatigue limit at R0.1 and 107 cycles is 20% increased, with respect to the machined surface, by wire-brush hammering. This improvement was discussed on the basis of the role of surface topography, stabilized residual stress and work-hardening on the fatigue-crack network nucleation and growth. The effects biaxial residual stress field and surface work-hardening were taken into account in the finite element model. A multi-axial fatigue criterion was proposed to predict the fatigue strength of aluminum alloy notched parts for both machined and treated states

  19. A Facile Method to Form a Densely Grafted PEO-b-P4VP Brush on Gold Surface

    Institute of Scientific and Technical Information of China (English)

    杨倩; 周常明; 陈旺; 方佳节; 陈道勇

    2012-01-01

    Here we report a facile method for the preparation of a PEO113-b-P4VP93 brush on gold surface with a grafting density as high as 1.32 chains/nm2; the P4VP blocks were physically adsorbed on gold surface forming an inner layer while the PEO blocks stretched towards the solution forming PEO brush. PEOl13-b-P4VPq3 micelles with P4VP core and PEO shell formed in methanol/water mixed solvents were used as the precursor. By adsorbing PEOII3-b-P4VP93 micelles from pure water, in which the density of the micelles is the largest, maximum amount of the micelles was adsorbed onto gold surface, and the adsorbed micelles existed as individual domains on the surface To prepare the polymer brush with a density as high as possible, we annealed the adsorbed micelles by metha- nol/water mixed solvent at the volume fraction of methanol (VF) of 20%, which was the proper proportion at which the core-forming P4VP chains began to be flexible but the integrity of the micelles was remained. At this volume fraction, almost all the adsorbed micelles originally existing as individual domains were transformed into a dense polymer brush.

  20. Comparison of the detection of periodontal pathogens in bacteraemia after tooth brushing by culture and molecular techniques

    Science.gov (United States)

    Figuero, Elena; González, Itziar; O´Connor, Ana; Diz, Pedro; Álvarez, Maximiliano; Herrera, David; Sanz, Mariano

    2016-01-01

    Background The prevalence and amounts of periodontal pathogens detected in bacteraemia samples after tooth brushing-induced by means of four diagnostic technique, three based on culture and one in a molecular-based technique, have been compared in this study. Material and Methods Blood samples were collected from thirty-six subjects with different periodontal status (17 were healthy, 10 with gingivitis and 9 with periodontitis) at baseline and 2 minutes after tooth brushing. Each sample was analyzed by three culture-based methods [direct anaerobic culturing (DAC), hemo-culture (BACTEC), and lysis-centrifugation (LC)] and one molecular-based technique [quantitative polymerase chain reaction (qPCR)]. With culture any bacterial isolate was detected and quantified, while with qPCR only Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans were detected and quantified. Descriptive analyses, ANOVA and Chi-squared tests, were performed. Results Neither BACTEC nor qPCR detected any type of bacteria in the blood samples. Only LC (2.7%) and DAC (8.3%) detected bacteraemia, although not in the same patients. Fusobacterium nucleatum was the most frequently detected bacterial species. Conclusions The disparity in the results when the same samples were analyzed with four different microbiological detection methods highlights the need for a proper validation of the methodology to detect periodontal pathogens in bacteraemia samples, mainly when the presence of periodontal pathogens in blood samples after tooth brushing was very seldom. Key words:Bacteraemia, periodontitis, culture, PCR, tooth brushing. PMID:26946197

  1. Adsorption of molecular brushes with polyelectrolyte backbones onto oppositely charged surfaces: A self-consistent field theory

    NARCIS (Netherlands)

    Feuz, L.; Leermakers, F.A.M.; Textor, M.; Borisov, O.V.

    2008-01-01

    The two-gradient version of the Scheutjens¿Fleer self-consistent field (SF-SCF) theory is employed to model the interaction between a molecular bottle brush with a polyelectrolyte backbone and neutral hydrophilic side chains and an oppositely charged surface. Our system mimics graft-copolymers with

  2. Tooth brushing and cardiometabolic risk factors in adolescents: Is there an association? the caspian-iii study

    Directory of Open Access Journals (Sweden)

    Roya Kelishadi

    2013-01-01

    Conclusions: Our findings suggest an independent and protective role of teeth brushing frequency for some cardiometabolic risk factors in adolescents. Increasing both the general health awareness and improving oral health should be considered in primordial and primary prevention of non-communicable diseases.

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

    DEFF Research Database (Denmark)

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

    2005-01-01

    The pig small intestinal brush border is a glycoprotein- and glycolipid-rich membrane that functions as a digestive/absorptive surface for dietary nutrients as well as a permeability barrier for pathogens. The present work was performed to identify carbohydrate-binding (lectinlike) proteins...

  4. Comparison of different approaches of interdental oral hygiene: interdental brushes versus dental floss.

    Science.gov (United States)

    Christou, V; Timmerman, M F; Van der Velden, U; Van der Weijden, F A

    1998-07-01

    The purpose of the present study was to compare in untreated patients suffering from moderate to severe periodontitis the efficacy of dental floss (DF) and interdental brushes (IDB) in the reduction of plaque, gingival inflammation, and probing depth in a 6-week period prior to subgingival debridement. Twenty-six patients (12 female, 14 male; mean age 37.4 years; range 27 to 72 years) were instructed to use DF for one side of the dentition and IDB for the other side as an adjunct to the daily toothbrushing for 6 weeks. Oral hygiene instructions for toothbrushing and the use of the two devices were given at baseline and at week 3. Measurements were carried out at baseline and at 6 weeks including plaque scores, probing depth, and 2 bleeding scores (periodontal pocket bleeding index and angulated bleeding index). With the IDB, the approximal plaque score at baseline of 3.09 reduced to 2.15 at 6 weeks and with DF from 3.10 to 2.47, respectively. IDB proved to remove significantly more plaque than DF. Baseline probing depth of 5.84 mm for IDB sites and 5.59 mm for DF sites was reduced to 5.01 mm at 6 weeks for both regimens. Analysis showed that the use of IDB resulted in a greater pocket reduction. Both bleeding indices were slightly reduced with IDB and DF, but no differences between devices were found. In relation to patient acceptance, more problems were observed with DF, and IDB were felt to be more efficacious. In conclusion, the results of the present study indicate that in combination with a manual toothbrush, the use of interdental brushes is more effective in removal of plaque and results in a larger reduction of probing depth than the use of dental floss. Although the differences were small, they indicate, in combination with patient preferences, that interdental brushes are to be considered preferable to floss for interdental plaque removal in patients suffering from moderate to severe periodontitis. PMID:9706852

  5. Effect of sugar-free gum in addition to tooth brushing on dental plaque and interdental debris

    Directory of Open Access Journals (Sweden)

    Pradnya Kakodkar

    2010-01-01

    Full Text Available Background: Chewing-gum may serve as an effective oral hygiene device when brushing may not be possible. The aim of the present study was to evaluate the effect of chewing sugar-free gum twice a day after meals in addition to tooth brushing on dental plaque and interdental debris. Methods : Twenty four (12 males and 12 females aged 20-21 years healthy third-year dental students participated in the study. It was a prospective single blind and non-randomized before and after study. The control group followed tooth brushing habit twice a day plus water rinsing after meals at noon and night for 10 days. The study group followed tooth brushing habit twice a day plus chewing one pellet of sugar-free gum after meals at noon and night for 30 minutes for 3 weeks. Personal hygiene performance index (PHP-M was used to assess the dental plaque and self-designed interdental debris index for interdental debris. ANOVA, Tukey and ′t′ tests were used for data analysis. The level of significance was fixed at α = 0.05. Results: The baseline percentages of cumulative plaque and interdental debris were 63.12% and 76.44%, respectively. There was no significant difference in the plaque scores following either water rinsing (61.73% or gum chewing (59.44% after meals, but a statistically significant reduction of 14.18% in interdental debris was observed among those who chewed the gum (P < 0.05. Conclusion: After meal, gum chewing in addition to daily tooth brushing reduced interdental debris, but had no effect on established buccal and lingual dental plaques.

  6. The impact of brush cytology from endoscopic retrograde cholangiopancreatography (ERCP) on patient management at a UK teaching hospital

    Science.gov (United States)

    Sethi, Rajiv; Singh, Kaushiki; Warner, Ben; Mahadeva, Ula; Wilkinson, Mark

    2016-01-01

    Introduction Patients with suspected pancreaticobiliary cancers frequently undergo endoscopic retrograde cholangiopancreatography (ERCP) to obtain brush cytology for confirmatory diagnosis. The outcome of this often leads to the management of the patient and can avoid more invasive investigations. There is a wide range of sensitivities and specificities reported in the literature. Aims To determine the accuracy of the brush cytology obtained at ERCP by performing a retrospective audit of all patients admitted to Guy's and St. Thomas’ Hospital for ERCP during 2008–2013. Also, to evaluate the impact of cytology results on patient care following ERCP. Method Data were collected from 4 January 2008 to 27 December 2013. This involved analysing EndoSoft (the in-house software for endoscopic data entry), Pathnet (the pathology database) and Electronic Patient Records. Results 162 patients underwent brush cytology during ERCP. 58 patients had positive cytology. With intention-to-treat analysis, sensitivity was 54.7%, specificity was 100.0% and negative predictive value was 53.9% with a positive predictive value of 100%. Patients with a positive brush cytology result required fewer investigations compared with patients with a negative cytology result. Conclusions Our results compare favourably with previous studies in the field. Brush cytology has been ignored in recent times due to perceived poor results and efficacy. Our audit shows that it can reduce the number of investigations required to reach a diagnosis of malignancy and so is a valuable tool in the diagnosis of pancreaticobiliary malignancies. However, better guidance on preparation of samples for cytology is needed to reduce the number of insufficient samples. PMID:27103983

  7. Cascade enzymatic catalysis in poly(acrylic acid) brushes-nanospherical silica for glucose detection.

    Science.gov (United States)

    Zhao, Yan; Wang, Ying; Zhang, Xiaobin; Kong, Rongmei; Xia, Lian; Qu, Fengli

    2016-08-01

    The ultrasensitive monitoring of glucose with a fast and accurate method is significant in potential therapeutics and optimizes protein biosynthesis. Incorporation of enzyme into matrix is considered as promising candidates for constructing highly sensitive glucose-responsive systems. In this study, three-dimensional poly(acrylic acid) brushes-nanospherical silica (PAA-nano silica) with high amplification capability and stability were used to covalently immobilize bienzymes for cascade enzymatic catalysis. The major advantages of PAA-nano silica-bienzyme co-incorporation is that the enzymes are proximity distribution, and such close confinement both minimized the diffusion of intermediates among the enzymes in the consecutive reaction and improve the utilization efficiency of enzymes, thereby enhancing the overall reaction efficiency and specificity. Thus, this present bienzymatic biosensor shows robust signal amplification and ultrasensitivity of glucose-responsive properties with a detection limit of 0.04μM. PMID:27216683

  8. Adaptive Input-Output Linearization Technique for Robust Speed Control of Brush less DC Motor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyeong Hwa; Baik, In Cheol; Kim, Hyun Soo; Youn, Myung Joong [Korea Advance Institute of Science and Technology, Taejon (Korea, Republic of)

    1997-06-01

    An adaptive input-output linearization technique for a robust speed control of a brush less DC (BLDC) motor is presented. By using this technique, the nonlinear motor model can be effectively linearized in Brunovski canonical form, and the desired speed dynamics can be obtained based on the linearized model. This control technique, however, gives an undesirable output performance under the mismatch of the system parameters and load conditions caused by the incomplete linearization. For the robust output response, the controller parameters will be estimated by a model reference adaptive technique where the disturbance torque and flux linkage are estimated. The adaptation laws are derived by the Popov`s hyper stability theory and positivity concept. The proposed control scheme is implemented on a BLDC motor using the software of DSP TMS320C30 and the effectiveness is verified through the comparative simulations and experiments. (author). 14 refs., 12 figs., 1 tab.

  9. X-ray Photon Correlation Spectroscopy of Silica Particles Grafted with Polymer Brush in Polystyrene Matrix

    Energy Technology Data Exchange (ETDEWEB)

    Hoshino, Taiki; Kikuchi, Moriya; Murakami, Daiki; Mitamura, Koji; Harada, Yoshiko; Takahara, Atsushi [JST, ERATO, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Ito, Kiminori; Tanaka, Yoshihito; Sasaki, Sono; Takata, Masaki, E-mail: t-hoshino@cstf.kyushu-u.ac.jp [RIKEN SPring-8 Center, Harima Institute (Japan)

    2011-01-01

    X-ray photon correlation spectroscopy system was setup at SPring-8, BL19LXU, and the partial coherence scattering data from the silica particles grafted with polymer brush in polystyrene matrix were measured. Firstly, the static speckle patterns were checked. Below the glass transition temperature of polystyrene (T{sub g}), speckles were clearly observed, on the other hand, above T{sub g}, the scattering patterns became smooth and speckles were hardly observed. These variances of the speckle patterns result from the particle motion. Secondly, from the time variance of the speckle data, time autocorrelation functions g{sub 2}(q,t) are calculated. While the flat behaviour of g{sub 2}(q,t) without relaxation were observed below T{sub g}, the relaxation behavior with relaxation time{approx}10{sup 0}-10{sup 1} were observed above T{sub g}

  10. POLYSACCHARIDES AND eDNA AID BACTERIAL ATTACHMENT TO POLYMER BRUSH COATINGS (PLL-g-PEG)

    DEFF Research Database (Denmark)

    Zeng, Guanghong; Ogaki, Ryosuke; Regina, Viduthalai R.; Meyer, Rikke Louise

    Polymer brush coatings of poly(ethylene glycol) are considered the gold standard for nonfouling surfaces, but nevertheless, a few bacteria manage to attach and initiate biofilm formation on these coatings. To achieve robust resistance against bacterial adhesion and biofilm formation, grafting...... in complete absence of bacterial colonization from Pseudomonas aeruginosa, Staphylococcus aureus and Staphylococcus epidermis, whereas the conventional PLL-g-PEG coatings only resisted colonization by P. aeruginosa and S. aureus, but not S. epidermidis. Colonization patterns were also reflected in...... of the conventional coating. These results explain why S. epidermidis, which produces polysaccharides and extracellular DNA, could successfully colonize the conventional PLL-g-PEG coatings. The ability of high-density PLL-g-PEG to resist polysaccharides, DNA, and bacterial adhesion of all strains is...

  11. Synthesis and characterization of a brush-like copolymer of polylactide grafted onto chitosan.

    Science.gov (United States)

    Liu, Y; Tian, F; Hu, K A

    2004-03-15

    A brush-like poly(DL)-lactide grafted onto chitosan as the backbone was investigated. The graft copolymerization was carried out with triethylaluminum as catalyst in toluene at 70 degrees C. It was found that a greater lactide content in the feeding ratio results in a higher grafting percentage. FTIR spectrometry, (1)H NMR, DSC scanning, and wide-angle X-ray scattering, respectively, are used to characterize these branch copolymers. A copolymer has a definite melting point when the molar feeding ratio of lactide to chitosan is more than 10:1, and the deltaH of the copolymers increases with the feed ratio of lactide to chitosan in feeding. PMID:14980828

  12. Phylogeography of the Buarremon brush-finch complex (Aves, Emberizidae) in Mesoamerica.

    Science.gov (United States)

    Navarro-Sigüenza, Adolfo G; Townsend Peterson, A; Nyari, Arpad; García-Deras, Gabriela M; García-Moreno, Jaime

    2008-04-01

    The Buarremon brush-finches represent a complex suite of populations distributed in the montane New World Tropics from Mexico south to South America. Traditional taxonomic arrangements have separated populations of this genus into three species, based on plumage variation, although plumage patterns are well known to exhibit homoplasy. We present a first detailed phylogeographic and phylogenetic study, focused on Mesoamerican populations, and signal the existence of strong differentiation among populations with a clear geographic structure. We find well differentiated clades for (1) the Sierra Madre Oriental and Sierra Madre del Sur in Oaxaca, (2) western Mexican populations, including the B. brunneinucha populations in the Sierra Madre del Sur and B. virenticeps, (3) Sierra Madre Oriental and Sierra de los Tuxtlas, (4) northern Central America, (5) southern Central America, (6) middle Central America, and (7) South America. We demonstrate a lack of concordance with plumage patterns, and argue for several additional species to be recognized in the complex. PMID:18272405

  13. Design optimization of brushed permanent magnet D C motor by genetic algorithm

    International Nuclear Information System (INIS)

    Because of field winding replacement with permanent magnet in brushed permanent magnet D C (PMDC) motors, field losses are eliminated and the structure of the motor is more simple. Efficiency of these motors is therefore increased and the manufacturing process is simplified. Hence, these motors are commonly used in low power applications and their design and optimization is an important consideration. Genetic algorithms are proposed for design optimization of PMD motors because of their independence to objective function structure and its derivative. In this paper genetic algorithms are evaluated for PMDC motor design optimization. an introduction is first presented about PMDC motors, general design procedure and elements of their optimization. Genetic algorithms are then briefly described. Finally results of optimization by genetic algorithms are compared with the one obtained using a conventional method

  14. Grafting polymer brushes on biomimetic structural surfaces for anti-algae fouling and foul release.

    Science.gov (United States)

    Wan, Fei; Pei, Xiaowei; Yu, Bo; Ye, Qian; Zhou, Feng; Xue, Qunji

    2012-09-26

    Sylgard-184 silicone elastomer negative replica and resorcinol-formaldehyde (RF) positive replica were made by biomimicking the patterns of natural Trifolium and three other kinds of leaves using the micromolding lithography. An effective antifouling (AF) polymer, poly(3-sulfopropyl methacrylate) (PSPMA), was then grafted on these replica surfaces via the surface-initiated atom transfer radical polymerization (SI-ATRP). The AF property of the modified biomimetic surfaces was tested via the settlement assay with two microalgae in different sizes, and their fouling-release (FR) property was evaluated by the removal assay. The results indicate that the structure of microspines on Trifolium leaf can inhibit settlement of microalgae and facilitate the cell release. The AF property was improved by modification with PSPMA brushes. PMID:22931043

  15. Chemical coding and chemosensory properties of cholinergic brush cells in the mouse gastrointestinal and biliary tract

    Directory of Open Access Journals (Sweden)

    Burkhard eSchütz

    2015-03-01

    Full Text Available The mouse gastro-intestinal and biliary tract mucosal epithelia harbor choline acetyltransferase (ChAT-positive brush cells with taste cell-like traits. With the aid of two transgenic mouse lines that express green fluorescent protein (EGFP under the control of the ChAT promoter (EGFPChAT and by using in situ hybridization and immunohistochemistry we found that EGFPChAT cells were clustered in the epithelium lining the gastric groove. EGFPChAT cells were numerous in the gall bladder and bile duct, and found scattered as solitary cells along the small and large intestine. While all EGFPChAT cells were also ChAT-positive, expression of the high-affinity choline transporter (ChT1 was never detected. Except for the proximal colon, EGFPChAT cells also lacked detectable expression of the vesicular acetylcholine transporter (VAChT. EGFPChAT cells were found to be separate from enteroendocrine cells, however they were all immunoreactive for cytokeratin 18 (CK18, transient receptor potential melastatin-like subtype 5 channel (TRPM5, and for cyclooxygenases 1 (COX1 and 2 (COX2. The ex vivo stimulation of colonic EGFPChAT cells with the bitter substance denatonium resulted in a strong increase in intracellular calcium, while in other epithelial cells such an increase was significantly weaker and also timely delayed. Subsequent stimulation with cycloheximide was ineffective in both cell populations. Given their chemical coding and chemosensory properties, EGFPChAT brush cells thus may have integrative functions and participate in induction of protective reflexes and inflammatory events by utilizing ACh and prostaglandins for paracrine signaling.

  16. Influence of surface PMPC brushes on tribological and biocompatibility properties of UHMWPE

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Wettability and blood compatibility of PMPC-grafted UHMWPE were improved. • The friction properties including the short and long term under high contact stress were investigated. • The PMPC brushes were sheared off from the surface with the increase of sliding cycles. - Abstract: Extremely efficient lubrication has been observed between natural joint surfaces and the friction coefficients can reach as low as 0.001. However, attaining the ultra-low friction coefficients between articulating cartilage surfaces in any artificial joints remains a challenge for bio-tribologists. In order to obtain the ultra-low friction coefficients as in natural joints, a biomimetic zwitterionic monomer 2-methacryloyloxyethyl phosphorylcholine (MPC) was grafted on the ultra high molecular weight polyethylene (UHMWPE) by UV radiation and self-polymerized to form brush-like structure. The results of total reflection (FT-IR/ATR) spectra and X-ray photoelectron spectroscopy (XPS) spectra indicated successful grafting of PMPC on to the UHMWPE surface (Polymerization of 2-methacryloyloxyethyl phosphorylcholine). The water contact angle of UHMWPE decreased from 80° to 15° after grafting PMPC for 45 min. Tribological properties were tested under high contact stress for a longer duration of time. The friction coefficient of the sample grafted with PMPC was found to be much lower than that of untreated UHMWPE at initial stage which increased gradually with the increase of the cycle till it attained the same level as that observed for untreated UHMWPE. The wear rate of modified samples was decreased by 37% and 46% in distilled water and saline, respectively. The highly hydrated PMPC layer provided efficient lubrication at the interface between the sliding couple leading to wear reduction of UHMWPE. Furthermore, blood compatibility of modified artificial joint materials was improved significantly, which has been attributed to the properties and

  17. Influence of surface PMPC brushes on tribological and biocompatibility properties of UHMWPE

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Dangsheng, E-mail: xiongds@163.com; Deng, Yaling; Wang, Nan; Yang, Yuanyuan

    2014-04-01

    Graphical abstract: - Highlights: • Wettability and blood compatibility of PMPC-grafted UHMWPE were improved. • The friction properties including the short and long term under high contact stress were investigated. • The PMPC brushes were sheared off from the surface with the increase of sliding cycles. - Abstract: Extremely efficient lubrication has been observed between natural joint surfaces and the friction coefficients can reach as low as 0.001. However, attaining the ultra-low friction coefficients between articulating cartilage surfaces in any artificial joints remains a challenge for bio-tribologists. In order to obtain the ultra-low friction coefficients as in natural joints, a biomimetic zwitterionic monomer 2-methacryloyloxyethyl phosphorylcholine (MPC) was grafted on the ultra high molecular weight polyethylene (UHMWPE) by UV radiation and self-polymerized to form brush-like structure. The results of total reflection (FT-IR/ATR) spectra and X-ray photoelectron spectroscopy (XPS) spectra indicated successful grafting of PMPC on to the UHMWPE surface (Polymerization of 2-methacryloyloxyethyl phosphorylcholine). The water contact angle of UHMWPE decreased from 80° to 15° after grafting PMPC for 45 min. Tribological properties were tested under high contact stress for a longer duration of time. The friction coefficient of the sample grafted with PMPC was found to be much lower than that of untreated UHMWPE at initial stage which increased gradually with the increase of the cycle till it attained the same level as that observed for untreated UHMWPE. The wear rate of modified samples was decreased by 37% and 46% in distilled water and saline, respectively. The highly hydrated PMPC layer provided efficient lubrication at the interface between the sliding couple leading to wear reduction of UHMWPE. Furthermore, blood compatibility of modified artificial joint materials was improved significantly, which has been attributed to the properties and

  18. Probing biofouling resistant polymer brush surfaces by atomic force microscopy based force spectroscopy.

    Science.gov (United States)

    Schön, Peter; Kutnyanszky, Edit; ten Donkelaar, Bas; Santonicola, M Gabriella; Tecim, Tugba; Aldred, Nick; Clare, Anthony S; Vancso, G Julius

    2013-02-01

    The protein repellency and biofouling resistance of zwitterionic poly(sulfobetaine methacrylate)(pSBMA) brushes grafted via surface initiated polymerization (SIP) from silicon and glass substrata was assessed using atomic force microscopy (AFM) adherence experiments. Laboratory settlement assays were conducted with cypris larvae of the barnacle Balanus amphitrite. AFM adherence includes the determination of contact rupture forces when AFM probe tips are withdrawn from the substratum. When the surface of the AFM tip is modified, adherence can be assessed with chemical specifity using a method known as chemical force microscopy (CFM). In this study, AFM tips were chemically functionalized with (a) fibronectin- here used as model for a nonspecifically adhering protein - and (b) arginine-glycine-aspartic acid (RGD) peptide motifs covalently attached to poly(methacrylic acid) (PMAA) brushes as biomimics of cellular adhesion receptors. Fibronectin functionalized tips showed significantly reduced nonspecific adhesion to pSBMA-modified substrata compared to bare gold (2.3±0.75 nN) and octadecanethiol (ODT) self-assembled monolayers (1.3±0.75 nN). PMAA and PMAA-RGD modified probes showed no significant adhesion to pSBMA modified silicon substrata. The results gathered through AFM protein adherence studies were complemented by laboratory fouling studies, which showed no adhesion of cypris larvae of Balanus amphitrite on pSBMA. With regard to its unusually high non-specific adsorption to a wide variety of materials the behavior of fibronectin is analogous to the barnacle cyprid temporary adhesive that also binds well to surfaces differing in polarity, charge and free energy. The antifouling efficacy of pSBMA may, therefore, be directly related to the ability of this surface to resist nonspecific protein adsorption. PMID:23138001

  19. The comparison between the effectiveness of six different tooth brushing methods on removing dental bacterial plaque

    Directory of Open Access Journals (Sweden)

    Saghazadeh M.

    2004-07-01

    Full Text Available Statement of Problem: There are different tooth brushing methods for removing dental plaque from tooth surfaces. The effectiveness of these methods, and the time needed for instruction, learning and using seem to be different. Also, it is possible that the effectiveness of each method reduces with time, based on its difficulty level and the reduction of the patient s attention in following the given instructions. Purpose: The aim of this research was to compare the effectiveness of six different accepted tooth brushing methods on total and specific teeth, as well as on special tooth surfaces. The research also compared the time needed for instruction, learning and using the methods. Materials and Methods: The study was designed as a single blind randomised controlled trial protocol to compare the six accepted tooth brushing methods: Roll, Bass, Charters (C, Modified Stillman (MS, and Modified Bass in two ways (MB1-MB2. 15 volunteers were selected from the basic science level dental students at Tehran University of Medical Sciences. All the six methods were instructed to each volunteer, using a randomly selected sequence. Each participant should, therefore, pass six consequent courses, by the same sequences as follow: 1st Visit: After polishing the teeth, the participant was asked to abstain any kind of tooth cleaning. - 2nd visit (48-72 hours later: O Leary Plaque Index (PI was recorded and then the randomised selected method was instructed. Then, the participant brushed his/her teeth and PI was registered again. The time needed for instruction and using the method was registered too. The participant was then asked to use this newly learned tooth brushing method twice a day for 7±1 days. - 3rd visit (7±1 days later: PI was recorded. The teeth were polished. The participant was asked to abstain any kind of tooth cleaning for 48-72 hours, as washout period of the previous method and preparation period for the next method (2nd visit of the next

  20. Efficacy and safety of BrushPicks, a new cleaning aid, compared to the use of Glide floss.

    Science.gov (United States)

    Yankell, Samuel L; Shi, Xiuren; Emling, Robert C

    2002-01-01

    The objective of this double-blind, four-week clinical study was to evaluate the efficacy of BrushPicks, a new cleaning aid, and Glide floss on the reduction of plaque area, gingivitis and bleeding on probing, and to monitor safety when these products were used in addition to toothbrushing with an ADA-Accepted toothbrush (Oral-B P35) and an ADA-Accepted fluoride-containing dentifrice (Crest Regular). No special instructions on or supervision of product use was conducted, other than requesting twice-a-day (morning and evening) use of the assigned products. Following a baseline examination, 63 qualifying adult male and female subjects from the Philadelphia, Pennsylvania area were randomized into two groups. Subjects were also told to use their assigned dental aid after each toothbrushing. Examinations for efficacy and safety were repeated after two and four weeks' use of the products. Sixty-two subjects completed all aspects of the study. There were no untoward side effects attributed to product use, reported or observed, at the two- or four-week examination times. At baseline, there were no significant differences in plaque, gingivitis or bleeding on probing mean scores between the BrushPicks and Glide floss groups. At the two- and four-week evaluation times, both the BrushPicks and Glide floss had numerically lower plaque scores compared to baseline levels. The only statistically significant reduction (p .01) was in the BrushPicks group, comparing the week two mean with the baseline value. Gingivitis (GI) at four weeks was statistically (p .05) lower in the BrushPicks group as compared to the Glide floss mean value. When the changes in scores from baseline to two weeks and to four weeks were assessed, the mean GI score for the Glide floss group was significantly lower at two weeks (p .01) compared to baseline, and also from two weeks to four weeks (p .001). The change in mean GI score for the Glide floss group from baseline to four weeks was also significant

  1. Development of Initiation Strategies for the Optimization and Stabilization of Brushes Formed by Surface-Initiated Radical Polymerization

    Science.gov (United States)

    Bain, Erich D.

    Three challenges facing the continued development of the surface-initiated (SI) polymerization field are addressed. The first challenge is that surface-initiated free radical polymerization (SI-FRP) is currently under-represented in literature reports, despite the fact that SI-FRP offers several important advantages over surface-initiated controlled radical polymerization (SI-CRP) and represents a complementary approach. Recognizing that simple, efficient, and safer approaches to synthesizing effective surface free radical initiators are needed, we present a novel synthetic route to an azo type free radical initiator that forms self-assembled monolayers on oxide coated surfaces such as silicon and glass. The yield of the novel synthetic approach is approximately double that of the previous method, and the usage of cyanide is reduced dramatically. We characterize the decomposition kinetics of the initiator using differential scanning calorimetry, comparing it with other similar initiators. We characterize the surface properties of initiator layers on silicon using ellipsometry, water contact angle measurements, and x-ray photoelectron spectroscopy (XPS). We demonstrate the use of the initiator for SI-FRP as well as SI-CRP mechanisms including reverse atom transfer radical polymerization (RATRP) and reversible addition-fragmentation transfer (RAFT) polymerization. A second challenge facing the field of SI polymerization involves the stability of grafted polymer brushes in aqueous environments and under tension, both of which are commonly encountered in many applications. We hypothesize that the mechanism of brush degrafting involves hydrolysis of ester backbone units in the initiator, which are ubiquitous in surface-bound polymerization initiator systems. The novel initiator described herein is unique in that its backbone consists of a chemically stable alkane chain, free of esters or other easily hydrolysable groups. We present results of experiments demonstrating

  2. Damage of target edges in brush-like geometry in the course of ELM-like plasma pulses in QSPA Kh-50

    International Nuclear Information System (INIS)

    Castellated edges of macro-brush armour elements of ITER divertor can be a source of molten/solid dust particles which are injected into the plasma. The targets that combined in brush-like geometry have been irradiated under different inclination angles in QSPA Kh-50. The cubic brushes element has typical size of 1 cm. The titanium was used to investigate dynamics of mountains’ formation. The onset of dust particles ejection from the exposed castellated targets has been studied. Formation of resolidified bridges through the gaps of brush-like targets due to the melt motion is studied in dynamics. With following plasma impacts such resolidified bridges became additional source of dust

  3. Damage of target edges in brush-like geometry in the course of ELM-like plasma pulses in QSPA Kh-50

    Energy Technology Data Exchange (ETDEWEB)

    Makhlaj, V.A., E-mail: makhlay@ipp.kharkov.ua [Institute of Plasma Physics of the NSC KIPT, 61108 Kharkov (Ukraine); Garkusha, I.E.; Aksenov, N.N. [Institute of Plasma Physics of the NSC KIPT, 61108 Kharkov (Ukraine); Bazylev, B. [Karlsruhe Institute of Technology (KIT), IHM, 76344 Karlsruhe (Germany); Byrka, O.V.; Chebotarev, V.V. [Institute of Plasma Physics of the NSC KIPT, 61108 Kharkov (Ukraine); Landman, I. [Karlsruhe Institute of Technology (KIT), IHM, 76344 Karlsruhe (Germany); Herashchenko, S.S.; Staltsov, V.V. [Institute of Plasma Physics of the NSC KIPT, 61108 Kharkov (Ukraine)

    2015-08-15

    Castellated edges of macro-brush armour elements of ITER divertor can be a source of molten/solid dust particles which are injected into the plasma. The targets that combined in brush-like geometry have been irradiated under different inclination angles in QSPA Kh-50. The cubic brushes element has typical size of 1 cm. The titanium was used to investigate dynamics of mountains’ formation. The onset of dust particles ejection from the exposed castellated targets has been studied. Formation of resolidified bridges through the gaps of brush-like targets due to the melt motion is studied in dynamics. With following plasma impacts such resolidified bridges became additional source of dust.

  4. Electrically evoked itch in humans.

    Science.gov (United States)

    Ikoma, Akihiko; Handwerker, Hermann; Miyachi, Yoshiki; Schmelz, Martin

    2005-01-01

    We compared itch sensations and axon reflex flare induced by transcutaneous electrical (0.08-8 ms, 2-200 Hz) and chemical (histamine iontophoresis; 100 microC) stimulation. Stimuli were applied to non-lesional volar wrist skin in 20 healthy human subjects and 10 patients with atopic dermatitis. Intensity of evoked itch and pain sensations were rated on a numerical rating scale (NRS) of 0 (no sensation) to 10 (the maximum sensation imaginable). The axon reflex erythema was measured by laser Doppler imager and areas of alloknesis (itch evoked by light brushing) and hyperknesis (itch evoked by pricking) were assessed psychophysically. Electrical stimulation was most effective for stimulus durations >or=2 ms and frequencies >or=50 Hz. It evoked pure itch as threshold sensation in 80% of the subjects that was perceived with a delay of approximately 1 s. Itch intensities of up to 7/10 were not accompanied by an axon reflex flare. In contrast, histamine provoked a massive increase of axon reflex erythema and maximum itch ratings of 3.1+/-0.2. The extention of alloknesis areas (2.3+/-0.5 cm) evoked by electrical stimulation clearly exceeded those induced by histamine (0.7+/-0.3 cm). Healthy subjects and patients with atopic dermatitis did not differ significantly in their response to either stimulation. We conclude that C-fiber activation underlies the electrically evoked itch sensation. The low electrical thresholds and the absence of an axon reflex flare suggest that these fibers are not identical with the previously described mechano-insensitive histamine responsive C fibers, but represent a separate peripheral neuronal system for the induction of itch. PMID:15621375

  5. “TO STUDY THE RELATIONSHIP OF ORAL HYGIENE AND GING IVITIS WITH THE INFLUENCE OF TOOTH BRUSHING HABITS IN CHIL DREN OF MEERUT DISTRICT”

    Directory of Open Access Journals (Sweden)

    Natasha

    2012-12-01

    Full Text Available ABSTRACT: Oral hygiene as a means and an end is a relatively novel concept which has only attained tactic public recognition as a desirable co smetic endeavor during this last century. Numerous factors may affect the distribution of plaq ue and gingivitis in the mouth. Of considerable importance must be the oral hygiene hab its of each person, which will be influenced by compliance and dexterity with tooth cl eaning methods. Most people exercise some measure of oral hygiene, and tooth brushing se ems to be the method of choice providing thorough and regular cleaning. AIMS & OBJECTIVES: This present study was conducted to investigate the effect of different brushing habits on dental plaque accumulation and gingival health of children of Meerut district. RESULTS: The results of the study revealed that plaque index and modified gingival index was not affected by sex and residing status of the children. Toothbrush was observed to be the best brushing aid , followed by name datum and then finger. Further , it was found that children who used tooth paste as a dentifrice showed lesser degree of plaque and gingivitis as compared to children who use d toothpowder and those who used no dentifrice. The scores were the highest in children who were using raakh as a dentifrice. Brushing once or twice daily proved to be the best f requency of brushing, followed by alternate days, occasionally and the highest for children who did not brush. It was observed that plaque was found to be directly related to gingivitis irre spective of the sex, residing status, type of brushing aid, dentifrice used and frequency of brus hing. Therefore, it can be concluded that more school dental health education programs should be carried out, focusing on the need of tooth brushing using a suitable dentifrice at least once a day to maintain good oral hygiene.

  6. Theranostic Unimolecular Micelles Based on Brush-Shaped Amphiphilic Block Copolymers for Tumor-Targeted Drug Delivery and Positron Emission Tomography Imaging

    OpenAIRE

    Guo, Jintang; Hong, Hao; Chen, Guojun; Shi, Sixiang; Nayak, Tapas R.; Theuer, Charles P.; Barnhart, Todd E.; Cai, Weibo; Gong, Shaoqin

    2014-01-01

    Brush-shaped amphiphilic block copolymers were conjugated with a monoclonal antibody against CD105 (i.e., TRC105) and a macrocyclic chelator for 64Cu-labeling to generate multifunctional theranostic unimolecular micelles. The backbone of the brush-shaped amphiphilic block copolymer was poly(2-hydroxyethyl methacrylate) (PHEMA) and the side chains were poly(l-lactide)-poly(ethylene glycol) (PLLA-PEG). The doxorubicin (DOX)-loaded unimolecular micelles showed a pH-dependent drug release profile...

  7. Testing of a cathode fabricated by painting with a brush pen for anode-supported tubular solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Renzhu; Zhao, Chunhua; Li, Junliang; Wang, Shaorong; Wen, Zhaoyin; Wen, Tinglian [CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS), 1295 Dingxi Road, Shanghai 200050 (China)

    2010-01-15

    We have studied the properties of a cathode fabricated by painting with a brush pen for use with anode-supported tubular solid oxide fuel cells (SOFCs). The porous cathode connects well with the electrolyte. A preliminary examination of a single tubular cell, consisting of a Ni-YSZ anode support tube, a Ni-ScSZ anode functional layer, a ScSZ electrolyte film, and a LSM-ScSZ cathode fabricated by painting with a brush pen, has been carried out, and an improved performance is obtained. The ohmic resistance of the cathode side clearly decreases, falling to a value only 37% of that of the comparable cathode made by dip-coating at 850 C. The single cell with the painted cathode generates a maximum power density of 405 mW cm{sup -2} at 850 C, when operating with humidified hydrogen. (author)

  8. Scalable air cathode microbial fuel cells using glass fiber separators, plastic mesh supporters, and graphite fiber brush anodes

    KAUST Repository

    Zhang, Xiaoyuan

    2011-01-01

    The combined use of brush anodes and glass fiber (GF1) separators, and plastic mesh supporters were used here for the first time to create a scalable microbial fuel cell architecture. Separators prevented short circuiting of closely-spaced electrodes, and cathode supporters were used to avoid water gaps between the separator and cathode that can reduce power production. The maximum power density with a separator and supporter and a single cathode was 75±1W/m3. Removing the separator decreased power by 8%. Adding a second cathode increased power to 154±1W/m3. Current was increased by connecting two MFCs connected in parallel. These results show that brush anodes, combined with a glass fiber separator and a plastic mesh supporter, produce a useful MFC architecture that is inherently scalable due to good insulation between the electrodes and a compact architecture. © 2010 Elsevier Ltd.

  9. Dissipative particle dynamics study of solvent mediated transitions in pores decorated with tethered polymer brushes in the form of stripes

    Directory of Open Access Journals (Sweden)

    J.M. Ilnytskyi

    2013-03-01

    Full Text Available We study self-assembly of a binary mixture of components A and B confined in a slit-like pore with the walls modified by the stripes of tethered brushes made of beads of a sort A. The emphasis is on solvent mediated transitions between morphologies when the composition of the mixture varies. For certain limiting cases of the pore geometry we found that an effective reduction of the dimensionality may lead to a quasi one- and two-dimensional demixing. The change of the environment for the chains upon changing the composition of the mixture from polymer melt to a good solvent conditions provides explanation for the mechanism of development of several solvent mediated morphologies and, in some cases, for switching between them. We found solvent mediated lamellar, meander and in-lined cylinder phases. Quantitative analysis of morphology structure is performed considering brush overlap integrals and gyration tensor components.

  10. Electrophysiological, morphological, and topological properties of two histochemically distinct subpopulations of cerebellar unipolar brush cells.

    Science.gov (United States)

    Kim, Jin-Ah; Sekerková, Gabriella; Mugnaini, Enrico; Martina, Marco

    2012-12-01

    Unipolar brush cells (UBCs) are excitatory cerebellar granular layer interneurons whose brush-like dendrites receive one-to-one mossy fiber inputs. Subclasses of UBCs differ primarily by expressing metabotropic glutamate receptor (mGluR) 1α or calretinin. We used GENSAT Tg(Grp-EGFP) BAC transgenic mice, which selectively express enhanced green fluorescent protein (EGFP) in mGluR1α-positive UBCs to compare the functional properties of the two subclasses. Compared to EGFP-negative UBCs, which include the calretinin-positive cells, EGFP-positive UBCs had smaller somata (area 48 vs 63 μm(2)), lower specific membrane resistance (6.4 vs. 13.7 KΩ cm(2)), were less prone to intrinsic firing, and showed more irregular firing (in cell-attached ~49 % were firing vs. ~88 %, and the CV was 0.53 vs. 0.32 for EGFP-negative cells). Some of these differences are attributable to higher density of background K(+) currents in EGFP-positive cells (at -120 mV, the barium-sensitive current was 94 vs. 37 pA in EGFP-negative cells); Ih, on the contrary, was more abundantly expressed in EGFP-negative cells (at -140 mV, it was -122 vs. -54 pA in EGFP-positive neurons); furthermore, while group II mGluR modulation of the background potassium current in EGFP-negative UBCs was maintained after intracellular dialysis, mGluR modulation in EGFP-positive UBCs was lost in whole-cell recordings. Finally, cell-attached firing was reversibly abolished by the GABA(B) activation in EGFP-positive, but not in EGFP-negative UBCs. Immunohistochemistry showed that EGFP-negative UBCs express GIRK2 at high density, while mGluR1α UBCs are GIRK2 negative, suggesting that GIRK2 mediates the mGluR-sensitive current in EGFP-negative UBCs. These data suggest that the two subclasses perform different functions in the cerebellar microcircuits. PMID:22528965

  11. RESEARCH ON THE POWER CONSUMPTION IN SANDING PROCESS WITH ABRASIVE BRUSHES, COMPARED TO THE WIDE BELT SANDING

    OpenAIRE

    Loredana Anne-Marie BĂDESCU; Octavia ZELENIUC; Ruxandra Loredana MĂDAN; Gheorghe-Cosmin SPÎRCHEZ

    2015-01-01

    This paper presents the modelling of over-finishing grinding with abrasive brushes and also a comparative study between the absorbed power when over-finishing grinding the beech, the spruce and the MDF with this kind of tools as compared to the absorbed power when over-finishing grinding under similar conditions using the wide belt sanding (grinding) technology, presenting the advantages of reconsidering such a technological process.

  12. Dentin surface treatment using a non-thermal argon plasma brush for interfacial bonding improvement in composite restoration

    OpenAIRE

    Ritts, Andy Charles; Li, Hao; Yu, Qingsong; Xu, Changqi; Yao, Xiaomei; Hong, Liang; Wang, Yong

    2010-01-01

    The objective of this study is to investigate the treatment effects of non-thermal atmospheric gas plasmas on dentin surfaces for composite restoration. Extracted unerupted human third molars were used by removing the crowns and etching the exposed dentin surfaces with 35% phosphoric acid gel. The dentin surfaces were treated by using a non-thermal atmospheric argon plasma brush for various durations. The molecular changes of the dentin surfaces were analyzed using FTIR/ATR and an increase in...

  13. Apical Invasion of Intestinal Epithelial Cells by Salmonella typhimurium Requires Villin to Remodel the Brush Border Actin Cytoskeleton

    OpenAIRE

    Lhocine, Nouara; Arena, Ellen T.; Bomme, Perrine; Ubelmann, Florent; Prévost, Marie-Christine; Robine, Sylvie; Sansonetti, Philippe J.

    2015-01-01

    Summary Salmonella invasion of intestinal epithelial cells requires extensive, though transient, actin modifications at the site of bacterial entry. The actin-modifying protein villin is present in the brush border where it participates in the constitution of microvilli and in epithelial restitution after damage through its actin-severing activity. We investigated a possible role for villin in Salmonella invasion. The absence of villin, which is normally located at the bacterial entry site, l...

  14. Synthesis of non-fouling poly[N-(2-hydroxypropyl) methacrylamide] brushes by photoinduced SET-LRP

    Czech Academy of Sciences Publication Activity Database

    Vorobii, Mariia; de los Santos Pereira, Andres; Pop-Georgievski, Ognen; Kostina, Nina Yu.; Rodriguez-Emmenegger, Cesar; Percec, V.

    2015-01-01

    Roč. 6, č. 23 (2015), s. 4210-4220. ISSN 1759-9954 R&D Projects: GA ČR(CZ) GJ15-09368Y; GA MŠk(CZ) LH13178; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:61389013 Keywords : polymer brushes * surface characterization * antifouling surfaces Subject RIV: CD - Macromolecular Chemistry Impact factor: 5.520, year: 2014

  15. Controlled RAFT polymerization of N-(tris(hydroxymethyl)methyl)acrylamide: towards new non-fouling polymer brushes

    Czech Academy of Sciences Publication Activity Database

    Surman, František; Rodriguez-Emmenegger, Cesar; de los Santos Pereira, Andres; Šubr, Vladimír; Kaňková, Dana; Sedláková, Zdeňka

    Ghent : Ghent University, 2012. s. 107. [Belgian-German [Macro]Molecular Meeting - Macro BeGe2012. 03.12.2012-04.12.2012, Houffalize] R&D Projects: GA ČR GAP106/12/1451; GA ČR GAP205/12/1702 Institutional support: RVO:61389013 Keywords : non-fouling polymer brush * RAFT polymerization Subject RIV: CD - Macromolecular Chemistry

  16. Effect of monoassociation with probiotic strain Bifidobacterium bifidum on enterocyte brush-border enzymes in gnotobiotic mice

    Czech Academy of Sciences Publication Activity Database

    Kozáková, Hana; Řeháková, Zuzana; Kolínská, Jiřina; Tlaskalová, Helena

    2002-01-01

    Roč. 88, č. 1 (2002), s. 113. ISSN 0007-1145. [ Probiotic s and Health /2001./. London, 13.09.2002-14.09.2002] R&D Projects: GA ČR GA306/99/1383; GA ČR GA310/01/0933; GA AV ČR IAA5020101 Keywords : enterocyte * brush * border Subject RIV: EE - Microbiology, Virology Impact factor: 2.491, year: 2002

  17. Treatment of carbon fiber brush anodes for improving power generation in air–cathode microbial fuel cells

    KAUST Repository

    Feng, Yujie

    2010-04-02

    Carbon brush electrodes have been used to provide high surface areas for bacterial growth and high power densities in microbial fuel cells (MFCs). A high-temperature ammonia gas treatment has been used to enhance power generation, but less energy-intensive methods are needed for treating these electrodes in practice. Three different treatment methods are examined here for enhancing power generation of carbon fiber brushes: acid soaking (CF-A), heating (CF-H), and a combination of both processes (CF-AH). The combined heat and acid treatment improve power production to 1370 mW m-2, which is 34% larger than the untreated control (CF-C, 1020 mW m-2). This power density is 25% higher than using only acid treatment (1100 mW m-2) and 7% higher than that using only heat treatment (1280 mW m-2). XPS analysis of the treated and untreated anode materials indicates that power increases are related to higher N1s/C1s ratios and a lower C-O composition. These findings demonstrate efficient and simple methods for improving power generation using graphite fiber brushes, and provide insight into reasons for improving performance that may help to further increase power through other graphite fiber modifications. © 2009 Elsevier B.V. All rights reserved.

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

    International Nuclear Information System (INIS)

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

  19. Affinity Separation of Lectins Using Porous Membranes Immobilized with Glycopolymer Brushes Containing Mannose or N-Acetyl-D-Glucosamine

    Directory of Open Access Journals (Sweden)

    Yoshiko Miura

    2013-07-01

    Full Text Available Porous membranes with glycopolymer brushes were prepared as biomaterials for affinity separation. Glycopolymer brushes contained acrylic acid and D-mannose or N-acetyl-D-glucosamine, and were formed on substrates by surface-initiated atom transfer radical polymerization. The presence of glycopolymer brush was confirmed by X-ray photoelectron spectroscopy, contact angle, and ellipsometry measurements. The interaction between lectin and the glycopolymer immobilized on glass slides was confirmed using fluorescent-labeled proteins. Glycopolymer-immobilized surfaces exhibited specific adsorption of the corresponding lectin, compared with bovine serum albumin. Lectins were continuously rejected by the glycopolymer-immobilized membranes. When the protein solution was permeated through the glycopolymer-immobilized membrane, bovine serum albumin was not adsorbed on the membrane surface. In contrast, concanavalin A and wheat germ agglutinin were rejected by membranes incorporating D-mannose or N-acetyl-D-glucosamine, respectively. The amounts of adsorbed concanavalin A and wheat germ agglutinin was increased five- and two-fold that of adsorbed bovine serum albumin, respectively.

  20. Diagnosis of pancreatic cancer by cytology and telomerase activity in exfoliated cells obtained by pancreatic duct brushing during endoscopy

    Institute of Scientific and Technical Information of China (English)

    Guo-Xiong Zhou; Jie-Fei Huang; Hong Zhang; Jian-Ping Chen

    2007-01-01

    BACKGROUND:Telomerase activity is reported to be speciifc and frequent in human pancreatic cancer. We conducted this study to assess the usefulness of monitoring telomerase activity in exfoliated cells obtained by pancreatic duct brushing during endoscopic retrograde cholangiopancreatography (ERCP) for the diagnosis of pancreatic cancer. METHODS:Exfoliated cells obtained by pancreatic duct brushing during ERCP from 21 patients (18 with pancreatic cancer, 3 with chronic pancreatitis) were examined. Telomerase activity was detected by polymerase chain reaction and telomeric repeat ampliifcation protocol assay (PCR-TRAP-ELISA). RESULTS:D450 values of telomerase activity were 0.446± 0.2700 in pancreatic cancer and 0.041±0.0111 in chronic pancreatitis. 77.8% (14/18) of patients with pancreatic cancer had cells with telomerase activity. None of the samples from patients with chronic pancreatitis showed telomerase activity, when the cutoff value of telomerase activity was set at 2.0. Cytological examination showed cancer cells in 66.7%(12/18) of the patients. CONCLUSIONS:Telomerase activity may be an early malignant event in pancreatic cancer development. Cytology and telomerase activity in cells obtained by pancreatic duct brushing may complement each other for the diagnosis of pancreatic cancer.

  1. Biological treatment of para-chlorophenol containing synthetic wastewater using rotating brush biofilm reactor

    International Nuclear Information System (INIS)

    A novel rotating brush biofilm reactor (RBBR) was used for para-chlorophenol (4-chlorophenol, 4-CP), COD and toxicity removal from synthetic wastewater containing different concentrations of 4-CP. Effects of major operating variables such as the feed 4-CP and COD concentrations and A/Q (biofilm surface area/feed flow rate) ratio on the performance of the biofilm reactor were investigated. A Box-Wilson statistical experiment design method was used by considering the feed 4-CP (0-1000 mg l-1), COD (2000-6000 mg l-1) and A/Q ratio (73-293 m2 day m-3) as the independent variables while the 4-CP, COD and toxicity removals were the objective functions. The results were correlated by a response function and the coefficients were determined by regression analysis. Percent 4-CP, COD and toxicity removals determined from the response functions were in good agreement with the experimental results. 4-CP, COD and toxicity removals increased with decreasing feed 4-CP and increasing A/Q ratio. Optimum conditions resulting in maximum COD, 4-CP and toxicity removals were found to be A/Q ratio of nearly 180 m2 day m-3, feed COD of nearly 4000 mg l-1 and feed 4-CP of less than 205 mg l-1

  2. Charged hydrophilic polymer brushes and their relevance for understanding marine biofouling.

    Science.gov (United States)

    Yandi, Wetra; Mieszkin, Sophie; di Fino, Alessio; Martin-Tanchereau, Pierre; Callow, Maureen E; Callow, James A; Tyson, Lyndsey; Clare, Anthony S; Ederth, Thomas

    2016-07-01

    The resistance of charged polymers to biofouling was investigated by subjecting cationic (PDMAEMA), anionic (PSPMA), neutral (PHEMA-co-PEG10MA), and zwitterionic (PSBMA) brushes to assays testing protein adsorption; attachment of the marine bacterium Cobetia marina; settlement and adhesion strength of zoospores of the green alga Ulva linza; settlement of barnacle (Balanus amphitrite and B. improvisus) cypris larvae; and field immersion tests. Several results go beyond the expected dependence on direct electrostatic attraction; PSPMA showed good resistance towards attachment of C. marina, low settlement and adhesion of U. linza zoospores, and significantly lower biofouling than on PHEMA-co-PEG10MA or PSBMA after a field test for one week. PDMAEMA showed potential as a contact-active anti-algal coating due to its capacity to damage attached spores. However, after field testing for eight weeks, there were no significant differences in biofouling coverage among the surfaces. While charged polymers are unsuitable as antifouling coatings in the natural environment, they provide valuable insights into fouling processes, and are relevant for studies due to charging of nominally neutral surfaces. PMID:27125564

  3. Natural Selection at the Brush-Border: Adaptations to Carbohydrate Diets in Humans and Other Mammals.

    Science.gov (United States)

    Pontremoli, Chiara; Mozzi, Alessandra; Forni, Diego; Cagliani, Rachele; Pozzoli, Uberto; Menozzi, Giorgia; Vertemara, Jacopo; Bresolin, Nereo; Clerici, Mario; Sironi, Manuela

    2015-09-01

    Dietary shifts can drive molecular evolution in mammals and a major transition in human history, the agricultural revolution, favored carbohydrate consumption. We investigated the evolutionary history of nine genes encoding brush-border proteins involved in carbohydrate digestion/absorption. Results indicated widespread adaptive evolution in mammals, with several branches experiencing episodic selection, particularly strong in bats. Many positively selected sites map to functional protein regions (e.g., within glucosidase catalytic crevices), with parallel evolution at SI (sucrase-isomaltase) and MGAM (maltase-glucoamylase). In human populations, five genes were targeted by positive selection acting on noncoding variants within regulatory elements. Analysis of ancient DNA samples indicated that most derived alleles were already present in the Paleolithic. Positively selected variants at SLC2A5 (fructose transporter) were an exception and possibly spread following the domestication of specific fruit crops. We conclude that agriculture determined no major selective event at carbohydrate metabolism genes in humans, with implications for susceptibility to metabolic disorders. PMID:26319403

  4. Natural Selection at the Brush-Border: Adaptations to Carbohydrate Diets in Humans and Other Mammals

    Science.gov (United States)

    Pontremoli, Chiara; Mozzi, Alessandra; Forni, Diego; Cagliani, Rachele; Pozzoli, Uberto; Menozzi, Giorgia; Vertemara, Jacopo; Bresolin, Nereo; Clerici, Mario; Sironi, Manuela

    2015-01-01

    Dietary shifts can drive molecular evolution in mammals and a major transition in human history, the agricultural revolution, favored carbohydrate consumption. We investigated the evolutionary history of nine genes encoding brush-border proteins involved in carbohydrate digestion/absorption. Results indicated widespread adaptive evolution in mammals, with several branches experiencing episodic selection, particularly strong in bats. Many positively selected sites map to functional protein regions (e.g., within glucosidase catalytic crevices), with parallel evolution at SI (sucrase-isomaltase) and MGAM (maltase-glucoamylase). In human populations, five genes were targeted by positive selection acting on noncoding variants within regulatory elements. Analysis of ancient DNA samples indicated that most derived alleles were already present in the Paleolithic. Positively selected variants at SLC2A5 (fructose transporter) were an exception and possibly spread following the domestication of specific fruit crops. We conclude that agriculture determined no major selective event at carbohydrate metabolism genes in humans, with implications for susceptibility to metabolic disorders. PMID:26319403

  5. Brush border membrane vesicles from dipteran midgut: a tool for studies on nutrient absorption

    Directory of Open Access Journals (Sweden)

    MG Leonardi

    2006-12-01

    Full Text Available Brush border membrane vesicles (BBMV from insects midgut can be successfully used to study several membrane phenomena, including nutrient absorption, ions permeability and insecticides mode of action. Midgut BBMV, purified from Musca domestica whole larvae, were used for the functional characterization of leucine transport. The amino acid uptake was accelerated in the presence of sodium or potassium and increased significantly when the extravesicular pH was 5.0, in agreement with the luminal pH in vivo. Radiolabelled leucine uptake was significantly reduced by an excess of cold leucine, histidine, serine and glycine, suggesting that the amino acid transporter is a broad scope carrier that does not recognize proline, glutamine and the dibasic amino acids lysine and arginine.Midgut BBMV were also obtained from homogenization of M. domestica and Bactrocera oleae adults. The final preparations showed a high enrichment in the specific activity of the BBM marker enzymes aminopeptidase N and γ-glutamyl transpeptidase, and were poorly contaminated by basolateral membranes, as indicated by the low specific activities of their marker enzyme Na+/K+ ATPase. Electron microscopy of B. oleae BBM fraction showed the presence of closed vesicles. Similar SDS-PAGE patterns, with numerous distinct bands, were detected for both B. oleae and M. domestica BBMV.

  6. Nanospherical Brush as Catalase Container for Enhancing the Detection Sensitivity of Competitive Plasmonic ELISA.

    Science.gov (United States)

    Huang, Xiaolin; Chen, Rui; Xu, Hengyi; Lai, Weihua; Xiong, Yonghua

    2016-02-01

    Plasmonic enzyme-linked immunosorbent assay (pELISA) based on catalase (CAT)-mediated gold nanoparticle growth shows great potential for the determination of disease-related biomarkers at ultralow concentrations by using sandwich formats. However, the relatively low sensitivity of this strategy using competitive formats limits its adoption for hapten detection. Herein, we present an improved competitive pELISA for ultrasensitive detection of ochratoxin A (OTA), where silica nanoparticles carrying poly(acrylic acid) brushes (SiO2@PAA) were used to decrease the affinity of competing antigens to anti-OTA monoclonal antibodies and amplify the signal as a "CAT container" (SiO2@PAA@CAT). The developed competitive pELISA exhibits extremely high sensitivity for OTA with detection limits of 10(-18) and 5 × 10(-20) g/mL by the naked eye and microplate reader, respectively. These values are at least 7 orders of magnitude lower than that of competitive CAT-based pELISA (10(-11) g/mL by the naked eye) and 8 orders of magnitude lower than that of horseradish peroxidase-based conventional ELISA (10(-11) g/mL by the microplate reader), respectively. Reliability and robustness of the proposed method were evaluated using actual agricultural products and human serum samples. This study demonstrated the potential of this modified method in practical applications involving the ultrasensitive detection of mycotoxins or other haptens. PMID:26719076

  7. TELOMERASE ACTIVITY OF FIBROBRONCHOSCOPIC BRUSHING CELLS IN NON-SMALL CELL LUNG CANCER

    Institute of Scientific and Technical Information of China (English)

    吴晓红; 应可净; 张行

    2003-01-01

    Objective: To evaluate the clinical significance of telomerase activity particularly in terms of prognostic impact in non-small cell lung cancer (NSCLC). Methods: The exfoliated cells from fibrobronchoscopic brushing were studied using polymerase chain reaction based on a telomerase repeat amplification protocal assay. Samples were taken from 60 NSCLC and 20 pulmonary infection cases. Results: Telomerase activity was detected in 53 of 60(88.3%) NSCLC specimens from the lesion side and in 5 of 25(20.0%) from the contralateral side but only in 2 of 20 pulmonary infection samples (P<0.05). The telomerase activity levels in NSCLC (medium 0.109) were significantly higher than those in pulmonary infection (medium 0.018, U=4.95, P<0.05). The telomerase activity levels in tumor staged IIIb-IV (medium 0.173) were higher than those in staged I-IIIa (medium 0.132, U=1.899, P<0.05). Conclusion: Telomerase activity is one of the most important marker in patients with NSCLC. Telomerase activity increases with the advance of tumor stage and can be used as a prognostic indicator of advanced NSCLC.

  8. Ion transport and selectivity in biomimetic nanopores with pH-tunable zwitterionic polyelectrolyte brushes

    Science.gov (United States)

    Zeng, Zhenping; Yeh, Li-Hsien; Zhang, Mingkan; Qian, Shizhi

    2015-10-01

    Inspired by nature, functionalized nanopores with biomimetic structures have attracted growing interests in using them as novel platforms for applications of regulating ion and nanoparticle transport. To improve these emerging applications, we study theoretically for the first time the ion transport and selectivity in short nanopores functionalized with pH tunable, zwitterionic polyelectrolyte (PE) brushes. In addition to background salt ions, the study takes into account the presence of H+ and OH- ions along with the chemistry reactions between functional groups on PE chains and protons. Due to ion concentration polarization, the charge density of PE layers is not homogeneously distributed and depends significantly on the background salt concentration, pH, grafting density of PE chains, and applied voltage bias, thereby resulting in many interesting and unexpected ion transport phenomena in the nanopore. For example, the ion selectivity of the biomimetic nanopore can be regulated from anion-selective (cation-selective) to cation-selective (anion-selective) by diminishing (raising) the solution pH when a sufficiently small grafting density of PE chains, large voltage bias, and low background salt concentration are applied.

  9. Cellulose nanocrystal-poly(oligo(ethylene glycol) methacrylate) brushes with tunable LCSTs.

    Science.gov (United States)

    Grishkewich, Nathan; Akhlaghi, Seyedeh Parinaz; Zhaoling, Yao; Berry, Richard; Tam, Kam C

    2016-06-25

    This paper reports on the synthesis of poly(oligoethylene glycol) methyl ether acrylate (POEGMA) grafted cellulose nanocrystals (CNCs) via surface initiated atom transfer radical polymerization (ATRP). An ATRP initiator (α-Bromoisobutyryl bromide) was covalently bonded to the surface of CNCs, followed by copolymerizing di(ethylene glycol) methyl ether methacrylate (MEO2MA) and oligoethylene glycol methyl ether methacrylate (OEGMA300) monomers from the surface using Cu(I)Br/2,2-dipyridal. Multiple POEGMA-g-CNC systems with varying MEO2MA/OEGMA300 content were synthesized, and they displayed a range of lower critical solution temperatures (LCSTs) in aqueous medium. μDSC endotherms and microstructural analysis indicated the collapse of POEGMA chains, followed by the aggregation of nanoparticles above their LCSTs. Cloud point measurements demonstrated a hysteresis in the heating and cooling of the POEGMA-g-CNC systems. It was found that the LCST of the nanoparticles could be tuned to between 23.8 to 63.8°C by adjusting the OEGMA300 content of the POEGMA brushes. PMID:27083811

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

    International Nuclear Information System (INIS)

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

  11. Preparation and characterization of nonfouling polymer brushes on poly(ethylene terephthalate) film surfaces.

    Science.gov (United States)

    Li, Jiehua; Tan, Dongsheng; Zhang, Xiaoqing; Tan, Hong; Ding, Mingming; Wan, Changxiu; Fu, Qiang

    2010-07-01

    In this study, a surface grafting of nonfouling poly(ethylene glycol) methyl ether acrylate (PEGMA) on poly(ethylene terephthalate) (PET) was carried out via surface-initiated atom-transfer radical polymerization (SI-ATRP) to improve hemocompatibility of polymer based biomaterials. To do this, the coupling agent with hydroxyl groups for the ATRP initiator was first anchored on the surface of PET films using photochemical method, and then these hydroxyl groups were esterified by bromoisobutyryl bromide, from which PET with various main chain lengths of PEGMA was prepared. The structures and properties of modified PET surfaces were investigated using water contact angle (WAC), ATR-FTIR, X-ray photoelectron spectroscopy (XPS) and Atomic force microscopy (AFM). The molecular weights of the free polymer from solution were determined by gel permeation chromatography (GPC). These results indicated that grafting of PEGMA on PET film is a simple way to change its surface properties. The protein adsorption resistance on the surfaces of PET was primarily evaluated by an enzyme-linked immunosorbent assay (ELISA). The result demonstrated that the protein adsorption could be well suppressed by poly(PEGMA) brush structure on the surface of PET. This work provides a new approach for polymers to enhance their biocompatibility. PMID:20399623

  12. Effects of Krenite? brush control agent (fosamine ammonium) on embryonic development in mallards and bobwhite

    Science.gov (United States)

    Hoffman, D.J.

    1988-01-01

    Fosamine ammonium (Krenite) is a highly water-soluble carbamoylphosphonate herbicide used to control woody brush. It has been reported to be teratogenic to avian embryos following spray application of the eggs. The embryotoxic and teratogenic potential of Krenite was examined in mallards (Anas platyrhynchos) and bobwhite (Colinus virginianus). At 96 h of development, eggs were briefly immersed in distilled water or in Krenite formulation in distilled water at concentrations of 1.5, 6.5, or 30% fosamine ammonium. At 6.5% active ingredient (a.i.), Krenite reduced hatching success in bobwhite and mallards to 85 and 33% of that in the distilled-water controls. At 30% a.i., Krenite caused 95 to 100% mortality in both species by the time of hatching. Early embryonic growth was impaired by 30% Krenite in both species. There was no evidence of teratogenesis of the axial skeleton, as reported previously in chickens and Japanese quail (Coturnix japonica). Most abnormal embryos had severe edema and some stunting. Mallard hatchlings from the 1.5 and 6.5% Krenite groups weighed significantly less than controls and had lower plasma alanine aminotransferase and aspartate aminotransferase activities, with elevated plasma glucose and cholesterol concentrations. Brain acetylcholinesterase activity was unaffected by Krenite in embryos and hatchlings.

  13. THEORETICAL INVESTIGATION OF THE INNOVATIVE BRUSH-GRATER DEVICE FOR EXTRACTING FOREST SEEDS FROM PERICARP

    Directory of Open Access Journals (Sweden)

    Sviridov L. T.

    2015-04-01

    Full Text Available Protective forest plantations, shelter belts and plantings along the highways of Central - Black Earth region and southern Russia are badly damaged, and in some areas destroyed. Therefore, they can not perform their functions and require major reconstruction or restoration. The most resistant and applicable trees and shrubs to create protective forest plantings are: maple, ash, elm species and three-thorned acacia, honey-locust, white and yellow acacia, and other legumes breeds with high drought tolerance, disease resistance, technogenic pollution and pest damage. For the creation and restoration of protective forest plantations we require seeds of these species containing pericarp. In Voronezh State Forestry Academy we have carried out a scientific research for creation of a machine for extracting seeds from the legumes. Analysis of the results of scientific research of prototyping machines showed that they were made without considered technological and mechanical properties of the legumes theoretical researches workflow machines for extracting seeds from the legumes and scientific basis of design parameters and operating modes. In this article we have a presentation of the experimental sample of the machine for extracting seeds from the legumes and theoretical investigation of the workflow in the batch hopper. According to the results of the study, we have obtained a mathematical expression, which allows you to define the parameters and modes of operation of a brush-grater device

  14. Disinfection of Streptococcus mutans Biofilm by a Non-Thermal Atmospheric Plasma Brush

    Science.gov (United States)

    Hong, Qing; Dong, Xiaoqing; Chen, Meng; Xu, Yuanxi; Sun, Hongmin; Hong, Liang; Yu, Qingsong

    2015-09-01

    This study investigated the argon plasma treatment effect on disinfecting dental biofilm by using an atmospheric pressure plasma brush. S. mutans biofilms were developed for 3 days on the surfaces of hydroxyapatite discs, which were used to simulate human tooth enamel. After plasma treatment, cell viability in the S. mutans biofilms was characterized by using MTT assay and confocal laser scanning microscopy (CLSM). Compared with the untreated control group, about 90% and 95% bacterial reduction in the biofilms was observed after 1 and 5 min plasma treatment, respectively. Scanning electron microscopy examination indicated severe cell damages occurred on the top surface of the plasma treated biofilms. CLSM showed that plasma treatment was effective as deep as 20 μm into the biofilms. When combined with 0.2% chlorhexidine digluconate solution, the plasma treatment became more effective and over 96% bacterial reduction was observed with 1 min plasma treatment. These results indicate that plasma treatment is effective and promising in dental biofilm disinfection.

  15. Neutral wetting brush layers for block copolymer thin films using homopolymer blends

    Science.gov (United States)

    Antonioli, Diego; Sparnacci, Katia; Laus, Michele; Lupi, Federico Ferrarese; Giammaria, Tommaso Jacopo; Seguini, Gabriele; Ceresoli, Monica; Perego, Michele; Gianotti, Valentina

    2016-05-01

    Binary homopolymer blends of two hydroxyl-terminated polystyrene (PS-OH) and polymethylmethacrylate (PMMA-OH) homopolymers (Mn ~ 16000 g mol-1) were grafted on SiO2 substrates by high-temperature (T > 150 °C), short-time (t blend composition and the processing parameters, an efficient surface neutralization path was identified, enabling the formation, in the block copolymer film, of homogeneous textures of lamellae or cylinders perpendicularly oriented with respect to the substrate. A critical interplay between the phase segregation of the homopolymer blends and their grafting process on the SiO2 was observed. In fact, the polar SiO2 is preferential for the PMMA-rich phase that forms a homogeneous layer on the substrate, while the PS-rich phase is located at the polymer-air interface. During the thermal treatment, phase segregation and grafting proceed simultaneously. Complete wetting of the PS rich phase on the PMMA rich phase leads to the formation of a PS/PMMA bilayer. In this case, the progressive diffusion of PS chains toward the polymer-SiO2 interface during the thermal treatment allows tuning of the brush layer composition

  16. Prospective evaluation of the protected specimen brush for the diagnosis of pulmonary infections in ventilated newborns.

    Science.gov (United States)

    Rigal, E; Roze, J C; Villers, D; Derriennic, M; David-Melon, V; Lacroix-Mechinaud, F; Mouzard, A

    1990-01-01

    The precise diagnosis of lower respiratory tract infection in the critically ill newborn remains a difficult challenge. The bronchoscopic protected specimen brush (PSB) is a reliable method in intubated adults. Because the bronchoscopic procedure is not generally available for young children, Zucker proposed a blind technique for introducing the PSB into the distal airways. His results were promising but were not compared with any bacteriologic reference method. Therefore, we wanted to evaluate this technique in comparison with the open lung biopsy (OLB) when it could be ethically accomplished. Eleven PSB were collected simultaneously with an OLB. The sensitivity of the PSB procedure was 100%, its specificity 88%, its positive predictive value 66%, and its negative predictive value 100%. There were no complications secondary to the PSB procedure. In this short study, the PSB procedure using a blind technique is safe and feasible to obtain uncontaminated specimens in intubated and ventilated newborns, and is largely accurate in identifying the bacterial etiologic agent of lower respiratory tract infection. PMID:2371075

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

    International Nuclear Information System (INIS)

    To investigate the pathogenetic mechanisms of interferon nephrotoxicity, we studied the effect of recombinant interferon alfa-2b on the uptake of 14C-D-glucose and 14C-L-alanine by rat renal brush-border-membrane vesicles. Interferon significantly inhibited 20 sec. sodium-dependent and 5 and 10 min. equilibrium uptake of both glucose and alanine. The inhibitory effect was dose dependent with maximum effect achieved at interferon concentration of 5 x 10-8M in the uptake media. The half-maximal inhibitory concentrations, IC50, of interferon on glucose uptake was 1.8 x 10-8M, and 5.4 x 10-9M on alanine uptake. Dixon plot analysis of uptake data was consistent with pure non-competitive inhibition. The inhibition constants, Ki, 1.5 x 10-8M for glucose uptake, and 7.3 x 10-9M for alanine uptake, derived from Dixon plots were in close agreement with the IC50s calculated from the semilog dose response curves. These observations reveal that direct interactions at the proximal tubule cell membrane are involved in the pathogenesis of interferon nephrotoxicity, and that its mechanism of nephrotoxicity is similar to that of other low molecular weight proteins

  18. Heparin blocks /sup 125/I-calmodulin internalization by isolated rat renal brush border membrane vesicles

    Energy Technology Data Exchange (ETDEWEB)

    Meezan, E.; Elgavish, A.; Roden, L.; Wallace, R.W.

    1986-03-05

    /sup 125/I-Calmodulin is internalized by isolated rat renal brush border membrane vesicles (BBV) in a time, temperature and calcium dependent manner. Internalization of /sup 125/I-calmodulin into the osmotically sensitive space of BBV was distinguished from binding of the ligand to the outer BBV surface by examining the interaction of ligand and BBV at different medium osmolarities (300-1100 mosm), uptake was inversely proportional to medium osmolarity. Internalized /sup 125/I-calmodulin was intact and Western blots of solubilized BBV with /sup 125/I-calmodulin demonstrated the presence of several calmodulin-binding proteins of 143, 118, 50, 47.5, 46.5 and 35 kilodaltons which could represent potential intravesicular binding sites for the ligand. Heparin and the related glycosaminoglycan heparin sulfate both showed a dose-dependent inhibition (0.5-50 ..mu..g/ml) of /sup 125/I-calmodulin uptake by BBV, but other sulfated and nonsulfated glycosaminoglycans including chondroitin sulfates, keratan sulfate and hyaluronic acid showed little or no inhibitory effect. Desulfation of heparin virtually abolished the inhibition of uptake while depolymerization reduced it. Heparin did not block the binding of /sup 125/I-calmodulin to BBV proteins as assessed by Western blotting technique suggesting its effect was on internalization of the ligand rather than on its association with internal membrane proteins.

  19. Disinfection of Streptococcus mutans biofilm by a non-thermal atmospheric plasma brush

    Science.gov (United States)

    Hong, Qing; Dong, Xiaoqing; Chen, Meng; Xu, Yuanxi; Sun, Hongmin; Hong, Liang; Wang, Yong; Yu, Qingsong

    2016-07-01

    This study investigated the argon plasma treatment effect on disinfecting dental biofilm by using an atmospheric pressure plasma brush. Streptococcus mutans biofilms were developed for 3 days on the surfaces of hydroxyapatite (HA) discs, which were used to simulate human tooth enamel. After plasma treatment, cell viability in the S. mutans biofilms was characterized by using 3-(4,5-dimethylazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay and confocal laser scanning microscopy (CLSM). Compared with the untreated control group, about 90% bacterial reduction in the biofilms was observed after 1 min plasma treatment. Scanning electron microscopy (SEM) examination indicated severe cell damages occurred on the top surface of the plasma treated biofilms. Confocal laser scanning microscopy (CLSM) showed that plasma treatment was effective as deep as 20 µm into the biofilms. When combined with antibiotic treatment using 0.2% chlorhexidine digluconate solution, the plasma treatment became more effective and over 96% bacterial reduction was observed with 1 min plasma treatment.

  20. Integrated Multilayer Nanogenerator Fabricated Using Paired Nanotip-to-Nanowire Brushes

    KAUST Repository

    Xu, Sheng

    2008-11-12

    We present a new approach to a nanogenerator (NG) that is composed of integrated, paired nanobrushes made of pyramid-shaped metal-coated ZnO nanotip (NTP) arrays and hexagonal-prism-shaped ZnO nanowire (NW) arrays, which were synthesized using a chemical approach at <100 °C on the two surfaces of a common substrate, respectively. The operation of the NGs relies on mechanical deflection/bending of the NWs, in which resonance of NWs is not required to activate the NG. This largely expands the application of the NGs from low frequency (approximately the hertz range) to a relatively high frequency (approximately the megahertz range) for effectively harvesting mechanical energies in our living environment. With one piece of such a structure stacked in close proximity over another to form a layer-by-layer matched brush architecture, direct current is generated by exciting the architecture using ultrasonic waves. A four-layer integrated NG is demonstrated to generate an output power density of 0.11 μW/cm 2 at 62 mV. The layer-by-layer assembly provides a feasible technology for building three-dimensional NGs for applications where force or pressure variations are available, such as a shoe pad, an underskin layer for airplanes, and next to a vibration source such as a car engine or tire. © 2008 American Chemical Society.

  1. Electricity Theory

    International Nuclear Information System (INIS)

    The text book composed of five parts, which are summary of this book, arrangement of electricity theory including electricity nad magnetism, a direct current, and alternating current. It has two dictionary electricity terms for a synonym. The last is an appendix. It is for preparing for test of officer, electricity engineer and fire fighting engineer.

  2. Synthesis and Multi-Stimuli-Responsive Behavior of Poly(N,N-dimethylaminoethyl methacrylate) Spherical Brushes under Different Modes of Confinement in Solution.

    Science.gov (United States)

    Dong, Zhixin; Mao, Jun; Wang, Dapeng; Yang, Muquan; Ji, Xiangling

    2015-08-18

    We report the synthesis and solution behavior of photo-, temperature-, pH-, and ion-responsive weak polyelectrolyte spherical brushes under different modes of confinement. The spherical brushes were prepared by copolymerization of N,N-dimethylaminoethyl methacrylate (DMAEMA) and 7-(2-methacryloyloxyethoxy)-4-methylcoumarin anchored to silica nanoparticles via surface-initiated atom transfer radical polymerization. The photo-cross-linking and reversibility of the nanoparticle-attached coumarin entities are detected by UV-visible spectroscopy and dynamic light scattering (DLS). The cross-linking density of poly(DMAEMA) (i.e., PDMAEMA) brushes could be easily controlled by alternating irradiation at wavelengths of 365 and 254 nm. Moreover, solution behavior under different pH levels and ionic strengths is systematically investigated in the PDMAEMA brush-polyelectrolyte chains confined only by a hard core, the cross-linked PDMAEMA brush-polyelectrolyte chains confined by a hard core and cross-linking points, and the corresponding hollow nanocapsules after removal of silica by etching-polyelectrolyte chains confined only by cross-linking points. These three models represent the different modes of confinement. DLS results indicate that the volume phase transition temperatures of the three models shift to lower temperatures with the increase in pH. The highest temperature is afforded to phase transition for hollow nanocapsules in solution, followed by the cross-linked PDMAEMA brushes. The hydrodynamic radius of the polyelectrolyte brush systems obviously decreases with the increase in ionic strength of the solution when adjusted by NaCl. PMID:26212408

  3. A study of usefulness of washes and brush cytology with respect to histopathology in diagnosis of lung malignancy by using fiberoptic bronchoscopy

    Directory of Open Access Journals (Sweden)

    Abhishek Bandyopadhyay

    2016-01-01

    Full Text Available Background: Examination of specimens obtained through flexible fiberoptic bronchoscope is important and often the initial diagnostic technique performed in patients with suspected malignant lung lesion. Aims: To evaluate the usefulness of cytological findings of bronchial washings (pre-and post-bronchoscopy and bronchial brushing in the diagnosis of lung malignancy with histopathology of bronchial biopsy, taking the latter as the confirmatory diagnostic test. Settings and Design: It was a cross-sectional observational study conducted in a tertiary care center. Subjects and Methods: A total of fifty patients with suspected lung malignancy (clinically and radiologically were included in this nonrandomized cross-sectional study. Bronchial brushings were obtained from all fifty cases. Prebiopsy bronchial washing (washing collected before the brushing and biopsy procedure and postbiopsy washing (washing at the end of the procedure were collected. Results: Prebiopsy (prebrushing and postbiopsy washing showed high specificity of 92.31%, but a very low sensitivity of 32.43% and 35.14%, respectively. Sensitivity and specificity of brushing were found to be 74.36% and 81.82%, respectively. Positive predictive value of prebiopsy (prebrushing washing, postbiopsy washing and brushing are 92.31%, 93.55%, and 92.86%, respectively. There was no significant difference in sensitivity between prebiopsy (prebrushing and postbiopsy washing (Fisher exact probability test; PA= 0.99. However, there was statistically significant difference between sensitivity of brushing with prebiopsy (prebrushing washing (Fisher exact probability test; PA = 0.0012793 and postbiopsy washing (Fisher exact probability test; PA = 0.00310282. Conclusions: Bronchial washing cytology in combination with brush cytology aids in the early diagnosis of lung malignancy in addition to histopathology.

  4. Influence of surface PMPC brushes on tribological and biocompatibility properties of UHMWPE

    Science.gov (United States)

    Xiong, Dangsheng; Deng, Yaling; Wang, Nan; Yang, Yuanyuan

    2014-04-01

    Extremely efficient lubrication has been observed between natural joint surfaces and the friction coefficients can reach as low as 0.001. However, attaining the ultra-low friction coefficients between articulating cartilage surfaces in any artificial joints remains a challenge for bio-tribologists. In order to obtain the ultra-low friction coefficients as in natural joints, a biomimetic zwitterionic monomer 2-methacryloyloxyethyl phosphorylcholine (MPC) was grafted on the ultra high molecular weight polyethylene (UHMWPE) by UV radiation and self-polymerized to form brush-like structure. The results of total reflection (FT-IR/ATR) spectra and X-ray photoelectron spectroscopy (XPS) spectra indicated successful grafting of PMPC on to the UHMWPE surface (Polymerization of 2-methacryloyloxyethyl phosphorylcholine). The water contact angle of UHMWPE decreased from 80° to 15° after grafting PMPC for 45 min. Tribological properties were tested under high contact stress for a longer duration of time. The friction coefficient of the sample grafted with PMPC was found to be much lower than that of untreated UHMWPE at initial stage which increased gradually with the increase of the cycle till it attained the same level as that observed for untreated UHMWPE. The wear rate of modified samples was decreased by 37% and 46% in distilled water and saline, respectively. The highly hydrated PMPC layer provided efficient lubrication at the interface between the sliding couple leading to wear reduction of UHMWPE. Furthermore, blood compatibility of modified artificial joint materials was improved significantly, which has been attributed to the properties and structures of PMPC grafted on the UHMWPE surface.

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

    Science.gov (United States)

    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. PMID:15027071

  6. Effect of a new pre-brushing rinse on dental plaque removal.

    Science.gov (United States)

    Vouros, J; Sakellari, D; Konstantinidis, A

    1994-11-01

    Non-prescription prebrushing rinses to facilitate dental plaque removal have been advertised in recent years. The purpose of the present study was to determine the plaque removal effectiveness of Plax (Colgate) prebrushing rinse by comparing it to a placebo solution. 19 dental students volunteered for this double blind study which consisted of 2 experimental periods. The following procedure was followed: 3 weeks after scaling and polishing, the participants abstained from oral hygiene for 3 days to allow dental plaque to accumulate. After plaque disclosing, the 4 mandibular incisors were photographed using a strictly defined technique, as described by Quirynen et al. Then the volunteers mouthrinsed for 30 s with 15 ml of a solution provided to them. Neither the volunteers nor the examiners knew which solution (test or control) was used. After mouthrinsing, the participants were allowed to brush their teeth and the remaining plaque was photographed again. During the 2nd experimental period, the same procedure was followed, and the 2nd solution was used for mouthrinsing. The effectiveness of the solutions was evaluated by comparing the proportion of dental plaque removed during the 2 experimental periods. The area of dental plaque was measured by an electronic high-precision device (planimeter). The proportion of plaque removed after rinsing with Plax was 0.40 +/- 0.23 and after rising with placebo 0.42 +/- 0.24, of the tooth surface (p = 0.962). Analysis of data by means of paired t-test between the 2 experimental periods revealed no beneficial effect regarding plaque removal when Plax was used. PMID:7852615

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

    Science.gov (United States)

    Nakano, Takanari; Inoue, Ikuo; Takenaka, Yasuhiro; Ono, Hiraku; Katayama, Shigehiro; Awata, Takuya; Murakoshi, Takayuki

    2016-01-01

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

  8. Modeling and Control of a Flux-Modulated Compound-Structure Permanent-Magnet Synchronous Machine for Hybrid Electric Vehicles

    OpenAIRE

    Zheng, Ping; Tong, Chengde; Bai, Jingang; Zhao, Jing; Sui, Yi; Song, Zhiyi

    2012-01-01

    The compound-structure permanent-magnet synchronous machine (CS-PMSM), comprising a double rotor machine (DRM) and a permanent-magnet (PM) motor, is a promising electronic-continuously variable transmission (e-CVT) concept for hybrid electric vehicles (HEVs). By CS-PMSM, independent speed and torque control of the vehicle engine is realized without a planetary gear unit. However, the slip rings and brushes of the conventional CS-PMSM are considered a major drawback for vehicle application. In...

  9. Analysis and Experiment of a Novel Brushless Double Rotor Machine for Power-Split Hybrid Electrical Vehicle Applications

    OpenAIRE

    Zhiyi Song; Chengde Tong; Jingang Bai; Qian Wu; Ping Zheng

    2013-01-01

    A novel brushless double rotor machine (BDRM) is proposed in this paper. The BDRM is an important component in the brushless compound-structure permanent-magnet synchronous machine (CS-PMSM) system, which is a promising technology for power-split hybrid electric vehicle (HEV) applications. Compared with common double rotor machines, the brushes and slip rings required by rotating winding have been omitted in the BDRM, thus there are no such problems as maintenance, friction losses and so fort...

  10. Effects of Grafting Density and Film Thickness on the Adhesion of Staphylococcus epidermidis to Poly(2-hydroxy ethyl methacrylate) and Poly(poly(ethylene glycol)methacrylate) Brushes.

    Science.gov (United States)

    Ibanescu, Sorin-Alexandru; Nowakowska, Justyna; Khanna, Nina; Landmann, Regine; Klok, Harm-Anton

    2016-05-01

    Thin polymer films that prevent the adhesion of bacteria are of interest as coatings for the development of infection-resistant biomaterials. This study investigates the influence of grafting density and film thickness on the adhesion of Staphylococcus epidermidis to poly(poly(ethylene glycol)methacrylate) (PPEGMA) and poly(2-hydroxyethyl methacrylate) (PHEMA) brushes prepared via surface-initiated atom transfer radical polymerization (SI-ATRP). These brushes are compared with poly(ethylene glycol) (PEG) brushes, which are obtained by grafting PEG onto an epoxide-modified substrate. Except for very low grafting densities (ρ = 1%), crystal violet staining experiments show that the PHEMA and PPEGMA brushes are equally effective as the PEG-modified surfaces in preventing S. epidermis adhesion and do not reveal any significant variations as a function of film thickness or grafting density. These results indicate that brushes generated by SI-ATRP are an attractive alternative to grafted-onto PEG films for the preparation of surface coatings that resist bacterial adhesion. PMID:26757483

  11. Electricity economics

    CERN Document Server

    Hu, Zhaoguang

    2013-01-01

    Systematically analyzing for the first time the production output from electricity consumption for enterprises, sectors, and industries, this study uses the function of EAI (electricity as input), and includes national E-GDP figures for more than 20 countries.

  12. Electric Power

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ China Council for the Promotion of International Trade Electric Power Industry Office (CCPIT Electric Power), one of the pro-fessional industrial branches of China Council for the Promotion of International Trade (CCPIT), was established in 2006.

  13. Effect of overhead spray and brush roller treatment on the survival of Pectobacterium and Salmonella on tomato surfaces.

    Science.gov (United States)

    Balaguero, Alina N; Sreedharan, Aswathy; Schneider, Keith R

    2015-01-01

    Overhead spray and brush roller (OSBR) treatment has been shown to remove significantly more Salmonella from tomato surfaces than flume treatment. However, OSBR is not widely used in tomato packing facilities compared with other commodities, and little is known about whether brushing causes microabrasions or other physical damage. Bacteria such as Pectobacterium, a soft rot-producing plant pathogen, and Salmonella, a human pathogen, show increased survival and growth on damaged tomato surfaces. This study evaluated whether OSBR treatment had a negative effect on the safety and/or marketability of tomatoes by examining its effect on Pectobacterium and Salmonella survival. Pectobacterium survival was evaluated on inoculated tomatoes that were OSBR treated with water or sanitizer (100 ppm of NaOCl, 5 ppm of ClO2, or 80 ppm of peracetic acid). A 15-s OSBR treatment using water or sanitizer achieved a 3-log CFU/ml reduction in Pectobacterium levels. Survival of Pectobacterium and Salmonella on OSBR-treated, untreated, and puncture-wounded tomatoes stored at 25°C and 75 to 85 % relative humidity for 7 days was also assessed. Both Pectobacterium and Salmonella populations declined rapidly on OSBR-treated and untreated tomatoes, indicating that brushing does not damage tomato fruit to the extent of promoting better pathogen survival. In contrast, the survival of both organisms was significantly (P ≤ 0.05) higher on artificially wounded fruit. These results indicate that OSBR treatment does not increase the survival and growth of Pectobacterium or Salmonella on tomato surfaces and that it is effective in reducing Pectobacterium levels on the surface of inoculated tomatoes. These results suggest that, if used properly, an OSBR system in packinghouses is effective in removing surface contamination and does not affect tomato quality or safety. PMID:25581177

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1989-02-01

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

  15. Squalamine, a novel cationic steroid, specifically inhibits the brush-border Na+/H+ exchanger isoform NHE3.

    Science.gov (United States)

    Akhter, S; Nath, S K; Tse, C M; Williams, J; Zasloff, M; Donowitz, M

    1999-01-01

    Squalamine, an endogenous molecule found in the liver and other tissues of Squalus acanthias, has antibiotic properties and causes changes in endothelial cell shape. The latter suggested that its potential targets might include transport proteins that control cell volume or cell shape. The effect of purified squalamine was examined on cloned Na+/H+ exchanger isoforms NHE1, NHE2, and NHE3 stably transfected in PS120 fibroblasts. Squalamine (1-h pretreatment) decreased the maximal velocity of rabbit NHE3 in a concentration-dependent manner (13, 47, and 57% inhibition with 3, 5, and 7 micrograms/ml, respectively) and also increased K'[H+]i. Squalamine did not affect rabbit NHE1 or NHE2 function. The inhibitory effect of squalamine was 1) time dependent, with no effect of immediate addition and maximum effect with 1 h of exposure, and 2) fully reversible. Squalamine pretreatment of the ileum for 60 min inhibited brush-border membrane vesicle Na+/H+ activity by 51%. Further investigation into the mechanism of squalamine's effects showed that squalamine required the COOH-terminal 76 amino acids of NHE3. Squalamine had no cytotoxic effect at the concentrations studied, as indicated by monitoring lactate dehydrogenase release. These results indicate that squalamine 1) is a specific inhibitor of the brush-border NHE isoform NHE3 and not NHE1 or NHE2, 2) acts in a nontoxic and fully reversible manner, and 3) has a delayed effect, indicating that it may influence brush-border Na+/H+ exchanger function indirectly, through an intracellular signaling pathway or by acting as an intracellular modulator. PMID:9886929

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

    International Nuclear Information System (INIS)

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

  17. An extended fluorescence in situ hybridization approach for the cytogenetic study of cholangiocarcinoma on endoscopic retrograde cholangiopancreatography brushing cytology preparations.

    Science.gov (United States)

    Vasilieva, Larisa E; Papadhimitriou, Stefanos I; Alexopoulou, Alexandra; Pavlidis, Dimitris; Kostopoulos, Ioannis; Georgiakaki, Maria; Xinopoulos, Dimitrios; Romanos, Andreas; Dourakis, Spyridon P

    2013-10-01

    The cytological diagnosis of cholangiocarcinoma has been significantly aided by applying a 4-probe fluorescence in situ hybridization system on endoscopic retrograde cholangiopancreatography brushing smears, aiming mainly at the detection of hyperdiploidy. However, this approach adds little to our understanding of the genetic background of the disease. With the prospect of obtaining additional data on chromosomal aberrations, we have extended the fluorescence in situ hybridization study, with the application of 4 independent 2-probe systems in 35 patients with documented cholangiocarcinoma. Fluorescence in situ hybridization assays were performed on endoscopic retrograde cholangiopancreatography brushing smears, with probes for the 7q31, 11q13 (CCND1), 17p53 (TP53), and 9p21 (INK4 locus) bands, together with the respective centromeric probe. Hyperdiploidy, involving at least 2 of the 4 chromosomes targeted, was found in 31 patients. 17p13 deletion was detected in 3, and 9p21 deletion, in 5 of the hyperdiploid cases, with the 2 aberrations concurrent in 1. CCND1 amplification was found in 1 case as the sole abnormality and in another together with hyperdiploidy, but in apparently unrelated clones. This work indicates that interphase fluorescence in situ hybridization is a practical and useful tool for the cytogenetic study of cholangiocarcinoma on endoscopic retrograde cholangiopancreatography brushing smears, which is often the only available tissue specimen of the tumor. Apart from hyperdiploidy, it provides additional data on the genetic profile of cholangiocarcinoma, especially regarding structural chromosomal aberrations and clonal diversity. This line of investigation may prove useful in the delineation of oncogenesis and the interpretation of the diverse clinical features of the disease. PMID:23845469

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

    International Nuclear Information System (INIS)

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

  19. Adaptive Speed Control Design for Brushed Permanent Magnet DC Motor Based on Worst-Case Analysis Approach

    Directory of Open Access Journals (Sweden)

    Sheng Zeng

    2013-01-01

    Full Text Available This paper presents the adaptive controller design for brushed permanent magnet DC motor used in velocity-tracking applications based on worst-case approach. We first formulate the robust adaptive control problem as a nonlinear H∞-control problem under imperfect state measurement, and then solve it using game-theoretic approach. The controller guarantees the boundedness of closed-loop signals with bounded exogenous disturbances, and achieves desired disturbance attenuation level with respect to the unmeasured exogenous disturbance inputs and the measured disturbance inputs. The strong robustness properties are illustrated by a simulation example.

  20. Non-Invasive Cytology Brush PCR for the Diagnosis and Causative Species Identification of American Cutaneous Leishmaniasis in Peru

    Science.gov (United States)

    Alba, Milena; Adaui, Vanessa; Arevalo, Jorge; Low, Donald E.; Llanos-Cuentas, Alejandro; Boggild, Andrea K.

    2012-01-01

    Background Traditional methods of detecting Leishmania from cutaneous lesions involve invasive diagnostic procedures, such as scrapings, which cause discomfort, require technical expertise, and carry risks of invasive procedures. We compared the performance of 2 novel, molecular-based non-invasive methods for the diagnosis of cutaneous leishmaniasis (CL). Methods Consecutive patients presenting to the Leishmania Clinic at the Hospital Nacional Cayetano Heredia were enrolled. PCR was performed on filter paper lesion impressions (FPLIs), cytology brushes, and lancets for detection of Leishmania DNA. Smears from lesion scrapings and leishmanin skin test were also performed. Outcome measures were sensitivity and specificity. Composite reference standard was any 2 of 5 tests positive. Species identification was performed by PCR assays of positive specimens. Results Ninety patients with 129 lesions were enrolled, 117 of which fulfilled reference criteria for a diagnosis of CL. Of these 117 lesions, 113 were positive by PCR of lancets used for lesion scrapings versus 116 by PCR of FPLIs (p = 0.930) or 116 by PCR of cytology brushes (p = 0.930). Sensitivity and specificity of PCR on lancets were 96.6% [95% CI 93.3–99.9%] and 100%, respectively. Sensitivity and specificity of FPLI PCR were 99.1% [95% CI 97.4–100%] and 100%, respectively. Sensitivity and specificity of cytology brush PCR were 99.1% [95% CI 97.4–100%] and 100%, respectively. Giemsa-stained lesion smear and leishmanin skin test had inferior sensitivities at 47.9% [95% CI 38.9–57.0%] and 82.3% [95% CI 73.9–90.7%], respectively, compared to PCR of invasive or non-invasive specimens (p<0.001). Conclusions Cytology brush PCR constitutes a sensitive and specific alternative to traditional diagnostic assays performed on invasive specimens such as lesion scrapings. It performs comparatively to non-invasive FPLI PCR. This novel, rapid, and well-tolerated method has the potential for widespread use in

  1. Influence of rare earths addition on residual stress of Fe-based coating prepared by brush plating technology

    Institute of Scientific and Technical Information of China (English)

    JIN Guo; LU Bingwen; HOU Dingding; CUI Xiufang; SONG Jiahui; LIU Erbao

    2016-01-01

    The effect of rare earths (La, Ce and Pr) addition on residual stress in iron coatings prepared by brush plating was investi-gated. The results showed that the addition of rare earth transformed the residual stress in the coating from tensile to compressive. To relieve the residual stress, on the one hand, RE elements segregated at the grain boundaries which restricted the coalescence of the grains and provided more capability of grain deformation. On the other hand, RE elements could purify detrimental element and ab-sorb hydrogen atoms in the coating. Among the three rare earths, elements lanthanum showed the most significant effect on surface morphology and residual stress.

  2. Electric motors for robotics; Moteurs electriques pour la robotique

    Energy Technology Data Exchange (ETDEWEB)

    Maye, P.

    2001-07-01

    Thanks to the recent progresses made in the domain of small motors and of their electronic control systems, the electrical actuators have become preponderant among the actuators used in robotics and automation. This book presents the knowledge necessary to deal with the domain of electric actuators. The three main types of motors encountered today are described with their characteristics: DC motors, brush-less DC motors and step-by-step motors. The mechanisms and their influence on the choice of a motor, the speed and position servo-controls and the overheating phenomena are detailed. An important part is devoted to the electronic circuits, responsible for a large part of the performances of actuators. Content: general considerations; principle and technology of DC motors; operation regimes; electronic power supplies; brush-less DC motors and their power supplies; step-by-step motors and their power supplies; servomechanisms; motors overheating; measurement of motors parameters; speed and position control; appendixes; dictionary, bibliography, index. (J.S.)

  3. Morphology and tribological properties of Ni/n-SiO2 composite coatings by pulse-reverse current brush-plating

    Institute of Scientific and Technical Information of China (English)

    TAN Jun; GUO Wen-cai; YANG Hong-jun; ZHOU Liang

    2005-01-01

    Ni/n-SiO2 composite coating was electrodeposited by brush-plating with pulse-reverse current(RC). The morphology, hardness, and tririological properties of the coating were investigated and compared with those of Ni and composite coatings electrodeposited with direct current (DC). The results indicate that Ni/n-SiO2 composite coating electrodeposited by RC, because of RC and the nano powders, has denser coating, finer crystal grains, high er hardness(HV650. 0, nearly 1.5 times higher than that of Ni coating electrodeposited by DC) and lower friction coefficient(nearly 0.62), as a result, in the wearing experiment, the Ni/n-SiO2 composite coating electrodeposited by RC has the least worn loss. So this kind of coating has better wear resistance. And RC electro brush-plating can be used as a new technology of brush-plating in the area of wear resistance.

  4. Electrical contracting

    CERN Document Server

    Neidle, Michael

    2013-01-01

    Electrical Contracting, Second Edition is a nine-chapter text guide for the greater efficiency in planning and completing installations for the design, installation and control of electrical contracts. This book starts with a general overview of the efficient cabling and techniques that must be employed for safe wiring design, as well as the cost estimation of the complete electrical contract. The subsequent chapters are devoted to other electrical contracting requirements, including electronic motor control, lighting, and electricity tariffs. A chapter focuses on the IEE Wiring Regulations an

  5. Electric vehicles

    Science.gov (United States)

    1990-03-01

    Quiet, clean, and efficient, electric vehicles (EVs) may someday become a practical mode of transportation for the general public. Electric vehicles can provide many advantages for the nation's environment and energy supply because they run on electricity, which can be produced from many sources of energy such as coal, natural gas, uranium, and hydropower. These vehicles offer fuel versatility to the transportation sector, which depends almost solely on oil for its energy needs. Electric vehicles are any mode of transportation operated by a motor that receives electricity from a battery or fuel cell. EVs come in all shapes and sizes and may be used for different tasks. Some EVs are small and simple, such as golf carts and electric wheel chairs. Others are larger and more complex, such as automobile and vans. Some EVs, such as fork lifts, are used in industries. In this fact sheet, we will discuss mostly automobiles and vans. There are also variations on electric vehicles, such as hybrid vehicles and solar-powered vehicles. Hybrid vehicles use electricity as their primary source of energy, however, they also use a backup source of energy, such as gasoline, methanol or ethanol. Solar-powered vehicles are electric vehicles that use photovoltaic cells (cells that convert solar energy to electricity) rather than utility-supplied electricity to recharge the batteries. These concepts are discussed.

  6. 虚拟毛笔建模研究现状与展望%Research and prospect of virtual brush modeling

    Institute of Scientific and Technical Information of China (English)

    侯增选; 杨广卿; 郭超; 郑栓柱

    2015-01-01

    Virtual brush modeling is a key technology in virtual painting.In order to truly reflect the characteristics of the real brush,enhance the reality of virtual painting,this paper reviewed the current research of virtual brush modeling.It summarised the basic idea,merits and demerits of typical modeling methods.It also discussed simulation effects of empirical-based modeling method and physical-based modeling method.Then,it briefly analyzed the interaction between brush and paper,paper and ink, human and computer,which had effects on virtual brush modeling.Finally,it analyzed the main difficulties and problems in vir-tual painting,and put forward the future research directions concerned with the virtual brush modeling.%为了真实地体现实际毛笔的特点,增强虚拟绘制真实感,通过对虚拟毛笔建模现状综述,归纳了典型建模方法的基本思想和优缺点,探讨了基于经验方法和基于物理方法的模拟效果;还简要分析了笔纸交互、纸墨交互及人机交互设备对虚拟毛笔建模的影响。最后分析了目前虚拟绘制中存在的主要难点和问题,指出了今后虚拟毛笔建模的研究方向。

  7. Brushed permanent magnet DC MLC motor operation in an external magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Yun, J.; St Aubin, J.; Rathee, S.; Fallone, B. G. [Department of Physics, University of Alberta, 11322-89 Avenue, Edmonton, Alberta T6G 2G7 (Canada) and Department of Oncology, Medical Physics Division, University of Alberta, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada); Department of Medical Physics, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada) and Department of Oncology, Medical Physics Division, University of Alberta, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada); Department of Physics, University of Alberta, 11322-89 Avenue, Edmonton, Alberta T6G 2G7 (Canada); Department of Medical Physics, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada) and Department of Oncology, Medical Physics Division, University of Alberta, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada)

    2010-05-15

    Purpose: Linac-MR systems for real-time image-guided radiotherapy will utilize the multileaf collimators (MLCs) to perform conformal radiotherapy and tumor tracking. The MLCs would be exposed to the external fringe magnetic fields of the linac-MR hybrid systems. Therefore, an experimental investigation of the effect of an external magnetic field on the brushed permanent magnet DC motors used in some MLC systems was performed. Methods: The changes in motor speed and current were measured for varying external magnetic field strengths up to 2000 G generated by an EEV electromagnet. These changes in motor characteristics were measured for three orientations of the motor in the external magnetic field, mimicking changes in motor orientations due to installation and/or collimator rotations. In addition, the functionality of the associated magnetic motor encoder was tested. The tested motors are used with the Varian 120 leaf Millennium MLC (Maxon Motor half leaf and full leaf motors) and the Varian 52 leaf MKII MLC (MicroMo Electronics leaf motor) including a carriage motor (MicroMo Electronics). Results: In most cases, the magnetic encoder of the motors failed prior to any damage to the gearbox or the permanent magnet motor itself. This sets an upper limit of the external magnetic field strength on the motor function. The measured limits of the external magnetic fields were found to vary by the motor type. The leaf motor used with a Varian 52 leaf MKII MLC system tolerated up to 450{+-}10 G. The carriage motor tolerated up to 2000{+-}10 G field. The motors used with the Varian 120 leaf Millennium MLC system were found to tolerate a maximum of 600{+-}10 G. Conclusions: The current Varian MLC system motors can be used for real-time image-guided radiotherapy coupled to a linac-MR system, provided the fringe magnetic fields at their locations are below the determined tolerance levels. With the fringe magnetic fields of linac-MR systems expected to be larger than the

  8. Brushed permanent magnet DC MLC motor operation in an external magnetic field

    International Nuclear Information System (INIS)

    Purpose: Linac-MR systems for real-time image-guided radiotherapy will utilize the multileaf collimators (MLCs) to perform conformal radiotherapy and tumor tracking. The MLCs would be exposed to the external fringe magnetic fields of the linac-MR hybrid systems. Therefore, an experimental investigation of the effect of an external magnetic field on the brushed permanent magnet DC motors used in some MLC systems was performed. Methods: The changes in motor speed and current were measured for varying external magnetic field strengths up to 2000 G generated by an EEV electromagnet. These changes in motor characteristics were measured for three orientations of the motor in the external magnetic field, mimicking changes in motor orientations due to installation and/or collimator rotations. In addition, the functionality of the associated magnetic motor encoder was tested. The tested motors are used with the Varian 120 leaf Millennium MLC (Maxon Motor half leaf and full leaf motors) and the Varian 52 leaf MKII MLC (MicroMo Electronics leaf motor) including a carriage motor (MicroMo Electronics). Results: In most cases, the magnetic encoder of the motors failed prior to any damage to the gearbox or the permanent magnet motor itself. This sets an upper limit of the external magnetic field strength on the motor function. The measured limits of the external magnetic fields were found to vary by the motor type. The leaf motor used with a Varian 52 leaf MKII MLC system tolerated up to 450±10 G. The carriage motor tolerated up to 2000±10 G field. The motors used with the Varian 120 leaf Millennium MLC system were found to tolerate a maximum of 600±10 G. Conclusions: The current Varian MLC system motors can be used for real-time image-guided radiotherapy coupled to a linac-MR system, provided the fringe magnetic fields at their locations are below the determined tolerance levels. With the fringe magnetic fields of linac-MR systems expected to be larger than the tolerance

  9. Effectiveness of oral hygiene after supervised tooth-brushing education in six-year-old children at a primary school in Vietnam

    OpenAIRE

    Lindmark, Ulrika; Do, Thi Thu Hien; Do, Quang Trung; Bengtsson, Ann

    2012-01-01

    Background: The prevalence of dental caries is very high among Vietnamese children why methods and techniques for good oral hygiene behaviours therefore is very important in caries prevention. Aim: To assess oral hygiene before and after supervised tooth-brushing education in six-yearold children. Design: A pilot study with a pre-post-test design was used. Forty children, six years of age, at a primary school in Hanoi, participated in the study. The modified Bass tooth-brushing method were ta...

  10. Reversible Swelling of Chitosan and Quaternary Ammonium Modified Chitosan Brush Layers: Effect of pH and Counter Anion Size and Functionality

    OpenAIRE

    Lee, Hyun-Su; Yee, Michael Q.; Eckmann, Yonaton Y.; Hickok, Noreen J.; Eckmann, David M.; Composto, Russell J.

    2012-01-01

    This study investigates the swelling of grafted polycationic brushes as a function of pH and anion type. The brushes are chitosan (CH) and chitosans with 27% and 51% degree of substitution (DS) of quaternary ammonium salt, denoted as CH-Q25 and CH-Q50, respectively. The water content and swelling behaviors are monitored using in situ quartz-crystal microbalance with dissipation (QCM-D). The pH varies from ~3.5 to 8.5, and the counter anion types include chloride, acetate, and citrate. At fixe...

  11. In vitro evaluation of human dental enamel surface roughness bleached with 35% carbamide peroxide and submitted to abrasive dentifrice brushing Avaliação in vitro da rugosidade superficial do esmalte dental humano clareado com peróxido de carbamida a 35% e submetido à escovação com dentifrícios abrasivos

    OpenAIRE

    Claudia Cia Worschech; José Augusto Rodrigues; Luis Roberto Marcondes Martins; Gláucia Maria Bovi Ambrosano

    2003-01-01

    The aim of this in vitro study was to evaluate the surface roughness of human enamel bleached with 35% carbamide peroxide at different times and submitted to different superficial cleaning treatments: G1 - not brushed; G2 - brushed with fluoride abrasive dentifrice; G3 - brushed with a non-fluoride abrasive dentifrice; G4 - brushed without dentifrice. Sixty fragments of human molar teeth with 4 x 4 mm were obtained using a diamond disc. The specimens were polished with sandpaper and abrasive ...

  12. Assembly and organization of poly(3-hexylthiophene) brushes and their potential use as novel anode buffer layers for organic photovoltaics.

    Science.gov (United States)

    Alonzo, José; Kochemba, W Michael; Pickel, Deanna L; Ramanathan, Muruganathan; Sun, Zhenzhong; Li, Dawen; Chen, Jihua; Sumpter, Bobby G; Heller, William T; Kilbey, S Michael

    2013-10-01

    Buffer layers that control electrochemical reactions and physical interactions at electrode/film interfaces are key components of an organic photovoltaic cell. Here the structure and properties of layers of semi-rigid poly(3-hexylthiophene) (P3HT) chains tethered at a surface are investigated, and these functional systems are applied in an organic photovoltaic device. Areal density of P3HT chains is readily tuned through the choice of polymer molecular weight and annealing conditions, and insights from optical absorption spectroscopy and semiempirical quantum calculation methods suggest that tethering causes intrachain defects that affect co-facial π-stacking of brush chains. Because of their ability to modify oxide surfaces, P3HT brushes are utilized as an anode buffer layer in a P3HT-PCBM (phenyl-C₆₁-butyric acid methyl ester) bulk heterojunction device. Current-voltage characterization shows a significant enhancement in short circuit current, suggesting the potential of these novel nanostructured buffer layers to replace the PEDOT:PSS buffer layer typically applied in traditional P3HT-PCBM solar cells. PMID:23955069

  13. High flux, positively charged loose nanofiltration membrane by blending with poly (ionic liquid) brushes grafted silica spheres

    International Nuclear Information System (INIS)

    Highlights: • SiO2 spheres were modified by poly (ionic liquid) brushes via RATRP. • Positively charged NF membranes were fabricated by incorporation of SiO2-PIL. • The membranes exhibited higher rejection for dyes and superior penetration for salts. - Abstract: Silica spheres modified by poly (ionic liquid) brushes, a novel positively charged nanomaterial is prepared by atom transfer radical polymerization (ATRP). A high flux positively charged loose nanofiltration membrane is fabricated via “blending-phase inversion” method. The morphology structures, hydrophilicity, thermal and mechanical properties, permeation performance of these membranes are investigated in detail. The results reveal that the hybrid membranes have enhanced surface hydrophilicity, water permeability, thermal stability, and mechanical properties. Characterization of membrane separation properties shows that the hybrid membranes possess higher salt permeability and relatively higher rejection for reactive dyes, which may open opportunities for the recycling of reactive dyes wastewater. Moreover, such hybrid membranes have an outstanding operational stability and salts concentration showed little effect on the separation properties

  14. High flux, positively charged loose nanofiltration membrane by blending with poly (ionic liquid) brushes grafted silica spheres

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Liang [School of Chemical Engineering and Energy, Zhengzhou University, Zhengzhou 450001 (China); Zhang, Yatao, E-mail: zhangyatao@zzu.edu.cn [School of Chemical Engineering and Energy, Zhengzhou University, Zhengzhou 450001 (China); UNESCO Center for Membrane Science and Technology, School of Chemical Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Wang, Yuanming; Zhang, Haoqin [School of Chemical Engineering and Energy, Zhengzhou University, Zhengzhou 450001 (China); Liu, Jindun, E-mail: liujindun@zzu.edu.cn [School of Chemical Engineering and Energy, Zhengzhou University, Zhengzhou 450001 (China)

    2015-04-28

    Highlights: • SiO{sub 2} spheres were modified by poly (ionic liquid) brushes via RATRP. • Positively charged NF membranes were fabricated by incorporation of SiO{sub 2}-PIL. • The membranes exhibited higher rejection for dyes and superior penetration for salts. - Abstract: Silica spheres modified by poly (ionic liquid) brushes, a novel positively charged nanomaterial is prepared by atom transfer radical polymerization (ATRP). A high flux positively charged loose nanofiltration membrane is fabricated via “blending-phase inversion” method. The morphology structures, hydrophilicity, thermal and mechanical properties, permeation performance of these membranes are investigated in detail. The results reveal that the hybrid membranes have enhanced surface hydrophilicity, water permeability, thermal stability, and mechanical properties. Characterization of membrane separation properties shows that the hybrid membranes possess higher salt permeability and relatively higher rejection for reactive dyes, which may open opportunities for the recycling of reactive dyes wastewater. Moreover, such hybrid membranes have an outstanding operational stability and salts concentration showed little effect on the separation properties.

  15. Rapid fabrication of poly(DL-lactide) nanofiber scaffolds with tunable degradation for tissue engineering applications by air-brushing.

    Science.gov (United States)

    Behrens, Adam M; Kim, Jeffrey; Hotaling, Nathan; Seppala, Jonathan E; Kofinas, Peter; Tutak, Wojtek

    2016-01-01

    Polymer nanofiber based materials have been widely investigated for use as tissue engineering scaffolds. While promising, these materials are typically fabricated through techniques that require significant time or cost. Here we report a rapid and cost effective air-brushing method for fabricating nanofiber scaffolds using a simple handheld apparatus, compressed air, and a polymer solution. Air-brushing also facilities control over the scaffold degradation rate without adversely impacting architecture. This was accomplished through a one step blending process of high (M w  ≈  100 000 g mol(-1)) and low (M w  ≈  25 000 g mol(-1)) molecular weight poly(DL-lactide) (PDLLA) polymers at various ratios (100:0, 70:30 and 50:50). Through this approach, we were able to control fiber scaffold degradation rate while maintaining similar fiber morphology, scaffold porosity, and bulk mechanical properties across all of the tested compositions. The impact of altered degradation rates was biologically evaluated in human bone marrow stromal cell (hBMSC) cultures for up to 16 days and demonstrated degradation rate dependence of both total DNA concentration and gene regulation. PMID:27121660

  16. Rapid fabrication of poly(DL-lactide) nanofiber scaffolds with tunable degradation for tissue engineering applications by air-brushing

    Science.gov (United States)

    Behrens, Adam M; Kim, Jeffrey; Hotaling, Nathan; Seppala, Jonathan E; Kofinas, Peter; Tutak, Wojtek

    2016-01-01

    Polymer nanofiber based materials have been widely investigated for use as tissue engineering scaffolds. While promising, these materials are typically fabricated through techniques that require significant time or cost. Here we report a rapid and cost effective air-brushing method for fabricating nanofiber scaffolds using a simple handheld apparatus, compressed air, and a polymer solution. Air-brushing also facilities control over the scaffold degradation rate without adversely impacting architecture. This was accomplished through a one step blending process of high (Mw ≈ 100 000 g mol−1) and low (Mw ≈ 25 000 g mol−1) molecular weight poly(DL-lactide) (PDLLA) polymers at various ratios (100:0, 70:30 and 50:50). Through this approach, we were able to control fiber scaffold degradation rate while maintaining similar fiber morphology, scaffold porosity, and bulk mechanical properties across all of the tested compositions. The impact of altered degradation rates was biologically evaluated in human bone marrow stromal cell (hBMSC) cultures for up to 16 days and demonstrated degradation rate dependence of both total DNA concentration and gene regulation. PMID:27121660

  17. Atmospheric electricity

    CERN Document Server

    Chalmers, J Alan

    1957-01-01

    Atmospheric Electricity brings together numerous studies on various aspects of atmospheric electricity. This book is composed of 13 chapters that cover the main problems in the field, including the maintenance of the negative charge on the earth and the origin of the charges in thunderstorms. After a brief overview of the historical developments of atmospheric electricity, this book goes on dealing with the general principles, results, methods, and the MKS system of the field. The succeeding chapters are devoted to some aspects of electricity in the atmosphere, such as the occurrence and d

  18. 化学机械抛光后板刷撩洗清洗%Post CMP Cleaning Using Chemically Enhanced Brush Scrubbing

    Institute of Scientific and Technical Information of China (English)

    赵岳星

    2004-01-01

    板刷擦洗是一种在化学机械抛光后清洗中常用的方法.它可以非常有效地把研磨剂颗粒从已抛光的晶圆表面去除掉.在氧化硅化学机械抛光的清洗工艺中,去离子水(或者稀释的氢氧化氨)是刷洗过程中常用的化学品起到的作用及刷洗的机械力对去除氧化硅研磨剂颗粒时所起的作用.%Brush scrubbing is widely used in post-CMP cleaning applications. It is highly effective in removing slurry abrasive particles from the polished wafer surfaces. In oxide CMP cleaning, DIW is commonly used during brush scrubbing. The role of mechanic force from the brushes in removing oxide slurry particles is studied in this work.The rest of this paper focuses on the effects of chemicals used in-situ with mechanical brush scrubbing. The chemical requirement for various post-CMP cleaning applications will be detailed in this paper.It is shown that the combined mechanical and chemical actions often give the best cleaning performance.

  19. Effects of brush management on the hydrologic budget and water quality in and adjacent to Honey Creek State Natural Area, Comal County, Texas, 2001--10

    Science.gov (United States)

    Banta, J. Ryan; Slattery, Richard N.

    2012-01-01

    Woody vegetation, including ashe juniper (Juniperus ashei), has encroached on some areas in central Texas that were historically oak grassland savannah. Encroachment of woody vegetation is generally attributed to overgrazing and fire suppression. Removing the ashe juniper and allowing native grasses to reestablish in the area as a brush management conservation practice (hereinafter referred to as "brush management") might change the hydrology in the watershed. These hydrologic changes might include changes to surface-water runoff, evapotranspiration, or groundwater recharge. The U.S. Geological Survey (USGS), in cooperation with Federal, State, and local partners, examined the hydrologic effects of brush management in two adjacent watersheds in Comal County, Tex. Hydrologic data were collected in the watersheds for 3-4 years (pre-treatment) depending on the type of data, after which brush management occurred on one watershed (treatment watershed) and the other was left in its original condition (reference watershed). Hydrologic data were collected in the study area for another 6 years (post-treatment). These hydrologic data included rainfall, streamflow, evapotranspiration, and water quality. Groundwater recharge was not directly measured, but potential groundwater recharge was calculated by using a simplified mass balance approach. This fact sheet summarizes highlights of the study from the USGS Scientific Investigations Report on which it is based.

  20. Clinical correlative study on early detection of oral cancer and precancerous lesions by modified oral brush biopsy and cytology followed by histopathology

    Directory of Open Access Journals (Sweden)

    Swati Gupta

    2014-01-01

    Conclusion: The results demonstrate that modified oral brush biopsy has higher efficacy than routine cytology and can be used as a potentially practical oral cancer screening tool in resource challenged settings. However, clinical judgment is of prime importance. Immediate biopsy is mandatory in highly suspicious lesions proposed under the diagnostic criteria of "clinically diagnosed carcinoma in situ".

  1. Microbial adhesion to surface-grafted polyacrylamide brushes after long-term exposure to PBS and reconstituted freeze-dried saliva

    NARCIS (Netherlands)

    Fundeanu, Irina; van der Mei, Henny C.; Schouten, Arend J.; Busscher, Henk J.

    2010-01-01

    Polyacrylamide (PAAm) brushes, covalently grafted from silicon wafer surfaces were examined for their ability to inhibit microbial adhesion after long-term exposure to PBS or reconstituted freeze-dried saliva for time intervals from 48 h up to 1 month at 37 degrees C. Microbial adhesion after exposu

  2. Effects of mechanical cleaning by manual brushing and abrasive blasting on lime render coatings on Architectural Heritage

    Directory of Open Access Journals (Sweden)

    Iglesias-Campos, M. A.

    2014-12-01

    Full Text Available This research studies the effects of mechanical cleaning by brushing and by abrasive blasting on the lime render coating of a façade. After analysing the properties of the material, the deposits to be removed and their possible influence on the treatment, different cleaning tests were made by manual brushing and by blasting with three varieties of abrasives at 45° and 75° angles, keeping the other parameters constant. Taking the restorer’s perspective as a starting point, and in order to fulfil the practical requirements of an intervention, tests were evaluated with macro-photography, USB digital microscope and stereomicroscope with 3D visualization and measurement. From the results can be concluded that abrasives with low friability and greater grain size than the space between mortar aggregates blasted at a 75° angle reduce the differential erosion compared to other abrasives; although manual brushing has less impact on the surface.En este trabajo se estudian los efectos de las limpiezas mecánicas con cepillado y con proyección de abrasivos sobre un revestimiento exterior de cal. Tras documentar las propiedades del material, de los depósitos superficiales y de su posible influencia en el tratamiento, se realizaron diferentes catas de limpieza con cepillado manual y con proyección de tres abrasivos con ángulos de 45° y 75° manteniendo constantes el resto de parámetros. Partiendo de la visión del conservador-restaurador y de un carácter práctico según las necesidades reales de intervención, los ensayos se evaluaron con macrofotografía, microscopio digital USB y microscopio estereoscópico con visualización y medición en 3D. De los resultados se determina que los abrasivos de baja friabilidad y granulometría mayor que el espacio entre los áridos del mortero proyectados con un ángulo de 75° reducen la erosión diferencial en comparación a otros abrasivos, aunque el cepillado manual altera menos la superficie.

  3. Reversible Swelling of Chitosan and Quaternary Ammonium Modified Chitosan Brush Layers: Effect of pH and Counter Anion Size and Functionality.

    Science.gov (United States)

    Lee, Hyun-Su; Yee, Michael Q; Eckmann, Yonaton Y; Hickok, Noreen J; Eckmann, David M; Composto, Russell J

    2012-10-01

    This study investigates the swelling of grafted polycationic brushes as a function of pH and anion type. The brushes are chitosan (CH) and chitosans with 27% and 51% degree of substitution (DS) of quaternary ammonium salt, denoted as CH-Q(25) and CH-Q(50), respectively. The water content and swelling behaviors are monitored using in situ quartz-crystal microbalance with dissipation (QCM-D). The pH varies from ~3.5 to 8.5, and the counter anion types include chloride, acetate, and citrate. At fixed pH, the water content and brush swelling increase as the DS increases. Whereas the CH-Q(50) brush layer shows symmetric swelling with a minimum near pH = 4.5, the swelling of CH and CH-Q(25) is relatively constant as pH decreases from 8.2 to 5.5, and then begins to increase near pH 4. These studies indicate that the symmetric swelling of CH-Q(50) is likely attributed to increasing protonation of primary amines for pH values below pH 6.5 and the quaternary ammonium salts above pH 6.5. At pH 4, the swelling of the CH brush increases upon exchanging the smaller chloridewith a bulkier acetate anion, which is less effective at screening intra/inter molecular repulsion. In contrast, upon exchanging the acetate with trifunctional citrate, CH and CH-Q(25) brushes collapse by 53 and 42%, respectively, because the citrate forms ionic cross-links. To test antibacterial properties, silicon oxide, CH and CH-Q(50) brush layers are exposed to 10(7)-10(8) cfu/ml of S. aureus for two days at 37 °C and exposed to stepped shear stresses in 2 min intervals. Whereas an S. aureus biofilm adheres strongly to silicon oxide and CH for stresses up to 12 dyne/cm(2), biofilms on CH-Q(50) detach at a relatively low shear stress, 1.5 dyne/cm(2). Due to their high degree of swelling that can be tuned via pH, counterion size and type, chitosan and quaternary modified chitosans have potential as responsive coatings for applications including MEMS/NEMS devices and drug eluting implants. PMID:23209343

  4. Immobilization of poly(MPC) brushes onto titanium surface by combining dopamine self-polymerization and ATRP: Preparation, characterization and evaluation of hemocompatibility in vitro

    International Nuclear Information System (INIS)

    Graphical abstract: The functional surface containing rich amino and hydroxyl groups was obtained by simple and easily dopamine self-polymerization. Poly (MPC) brushes were successfully immobilized on titanium surface by combining acylation reaction and ATRP. This chemical and biomimetic modified titanium surface effectively inhibits platelet adhesion and activation. - Highlights: • Polydopamine coating provides amino and hydroxyl groups for second reactivity. • Poly(MPC) brushes covalently immobilized on coating by surface initiated ATRP. • In vitro hemocompatibility of biomimetic modified Ti was better than unmodified. - Abstract: Poly(2-methacryloyloxyethyl phosphorylcholine(MPC)) has been studied in many biomedical fields because of good biocompatibility, such as hemocompatibility, inhibiting protein adhesion, antifouling, and so on. To achieve good hemocompatibility of titanium (Ti) surface, bio-inspired poly(MPC) brushes were grafted from Ti substrate covalently. In this work, the surface of Ti was first coated with polydopamine, and got a surface bearing −NH2 and −OH groups which could be bridged with poly(MPC) via atom transfer radical polymerization. Water contact angle decreased to 51.3° when titanium grafted with poly(MPC) brushes. The data of Infrared Spectroscopy and X-ray photoelectron spectroscopy (XPS) indicated that poly(MPC) was successfully grafted onto the surface of titanium. Platelet-rich plasma (PRP) adhesion test and lactate dehydrogenase (LDH) assay showed that the number of platelets adhered on the surface of modified-titanium was much less than that of unmodified titanium and platelets did not aggregate and distort. Thus, the simple and chemical method of immobilization of poly(MPC) brushes has potential application for improving hemocompatibility for cardiovascular stent and some other biomaterials

  5. Evaluation of boronate-containing polymer brushes and gels as substrates for carbohydrate-mediated adhesion and cultivation of animal cells.

    Science.gov (United States)

    Ivanov, Alexander E; Kumar, Ashok; Nilsang, Suthasinee; Aguilar, Maria-Rosa; Mikhalovska, Lyubov I; Savina, Irina N; Nilsson, Lars; Scheblykin, Ivan G; Kuzimenkova, Marina V; Galaev, Igor Yu

    2010-02-01

    Boronate-containing thin polyacrylamide gels (B-Gel), polymer brushes (B-Brush) and chemisorbed organosilane layers (B-COSL) were prepared on the surface of glass slides and studied as substrates for carbohydrate-mediated cell adhesion. B-COSL- and B-Brush-modified glass samples exhibited multiple submicron structures densely and irregularly distributed on the glass surface, as found by scanning electron microscopy and atomic force microscopy. B-Gel was ca. 0.1 mm thick and contained pores with effective size of 1-2 microm in the middle and of 5-20 microm on the edges of the gel sample as found by confocal laser scanning microscopy. Evidence for the presence of phenylboronic acid in the samples was given by time-of-flight secondary ion mass-spectrometry (ToF SIMS), contact angle measurements performed in the presence of fructose, and staining with Alizarin Red S dye capable of formation specific, fluorescent complexes with boronic acids. A comparative study of adhesion and cultivation of animal cells on the above substrates was carried out using murine hybridoma M2139 cell line as a model. M2139 cells adhered to the substrates in the culture medium without glucose or sodium pyruvate at pH 8.0, and then were cultivated in the same medium at pH 7.2 for 4 days. It was found that the substrates of B-Brush type were superior both regarding cell adhesion and viability of the adhered cells, among the substrates studied. MTT assay confirmed proliferation of M2139 cells on B-Brush substrates. Some cell adhesion was also registered in the macropores of B-Gel substrate. The effects of surface microstructure of the boronate-containing polymers on cell adhesion are discussed. Transparent glass substrates grafted with boronate-containing copolymers offer good prospects for cell adhesion studies and development of cell-based assays. PMID:19837569

  6. Characterization of the airborne bacteria community at different distances from the rotating brushes in a wastewater treatment plant by 16S rRNA gene clone libraries

    Institute of Scientific and Technical Information of China (English)

    Yunping Han; Lin Li; Junxin Liu

    2013-01-01

    Biological risks of bioaerosols emitted from wastewater treatment processes have attracted wide attention in the recent years.However,the culture-based analysis method has been mostly adopted for detecting the bacterial community in bioaerosols,which may result in the underestimation of total microorganism concentration as not all microorganisms are cultivable.In this study,oligonucleotide fingerprinting of 16S rRNA genes was applied to reveal the composition and structure of the bacterial community in bioaerosols from an Orbal oxidation ditch in a Beijing wastewater treatment plant (WWTP).Bioaerosols were collected at different distances from the aerosol source,rotating brushes,and the sampling height was 1.5 m which is the common respiratory height of a human being.The bacterial communities of bioaerosols were diverse,and the lowest bacterial diversity was found at the sampling site just after the rotating brush rotating brush.A large proportion of bacteria in bioaerosols were affiliated with Proteobacteria and Bacteroidetes.Numerous bacteria present in the bioaerosols also emerged in water,indicating that the bacterial community in the bioaerosols was related to that of the aerosols' sources.The forced aeration of rotating brushes brought about observably distinct bacterial communities between sampling sites situated before and after the rotating brush.Isolation sources of closest relatives in bioaerosols done libraries were associated with the aqueous environment in the WWTP.Common potential pathogens in bioaerosols as well as those not reported in previous research were also analyzed in this study.Measures should be adopted to reduce the emission of bioaerosols and prevent their exposure to workers.

  7. Characterization of the airborne bacteria community at different distances from the rotating brushes in a wastewater treatment plant by 16S rRNA gene clone libraries.

    Science.gov (United States)

    Han, Yunping; Li, Lin; Liu, Junxin

    2013-01-01

    Biological risks of bioaerosols emitted from wastewater treatment processes have attracted wide attention in the recent years. However, the culture-based analysis method has been mostly adopted for detecting the bacterial community in bioaerosols, which may result in the underestimation of total microorganism concentration as not all microorganisms are cultivable. In this study, oligonucleotide fingerprinting of 16S rRNA genes was applied to reveal the composition and structure of the bacterial community in bioaerosols from an Orbal oxidation ditch in a Beijing wastewater treatment plant (WWTP). Bioaerosols were collected at different distances from the aerosol source, rotating brushes, and the sampling height was 1.5 in which is the common respiratory height of a human being. The bacterial communities of bioaerosols were diverse, and the lowest bacterial diversity was found at the sampling site just after the rotating brush rotating brush. A large proportion of bacteria in bioaerosols were affiliated with Proteobacteria and Bacteroidetes. Numerous bacteria present in the bioaerosols also emerged in water, indicating that the bacterial community in the bioaerosols was related to that of the aerosols' sources. The forced aeration of rotating brushes brought about observably distinct bacterial communities between sampling sites situated before and after the rotating brush. Isolation sources of closest relatives in bioaerosols clone libraries were associated with the aqueous environment in the WWTP. Common potential pathogens in bioaerosols as well as those not reported in previous research were also analyzed in this study. Measures should be adopted to reduce the emission of bioaerosols and prevent their exposure to workers. PMID:23586294

  8. Immobilization of poly(MPC) brushes onto titanium surface by combining dopamine self-polymerization and ATRP: Preparation, characterization and evaluation of hemocompatibility in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Wenyong; Yang, Ping; Li, Jingan; Li, Shiqi; Li, Peichuang; Zhao, Yuancong, E-mail: Zhaoyc7320@163.com; Huang, Nan

    2015-09-15

    Graphical abstract: The functional surface containing rich amino and hydroxyl groups was obtained by simple and easily dopamine self-polymerization. Poly (MPC) brushes were successfully immobilized on titanium surface by combining acylation reaction and ATRP. This chemical and biomimetic modified titanium surface effectively inhibits platelet adhesion and activation. - Highlights: • Polydopamine coating provides amino and hydroxyl groups for second reactivity. • Poly(MPC) brushes covalently immobilized on coating by surface initiated ATRP. • In vitro hemocompatibility of biomimetic modified Ti was better than unmodified. - Abstract: Poly(2-methacryloyloxyethyl phosphorylcholine(MPC)) has been studied in many biomedical fields because of good biocompatibility, such as hemocompatibility, inhibiting protein adhesion, antifouling, and so on. To achieve good hemocompatibility of titanium (Ti) surface, bio-inspired poly(MPC) brushes were grafted from Ti substrate covalently. In this work, the surface of Ti was first coated with polydopamine, and got a surface bearing −NH{sub 2} and −OH groups which could be bridged with poly(MPC) via atom transfer radical polymerization. Water contact angle decreased to 51.3° when titanium grafted with poly(MPC) brushes. The data of Infrared Spectroscopy and X-ray photoelectron spectroscopy (XPS) indicated that poly(MPC) was successfully grafted onto the surface of titanium. Platelet-rich plasma (PRP) adhesion test and lactate dehydrogenase (LDH) assay showed that the number of platelets adhered on the surface of modified-titanium was much less than that of unmodified titanium and platelets did not aggregate and distort. Thus, the simple and chemical method of immobilization of poly(MPC) brushes has potential application for improving hemocompatibility for cardiovascular stent and some other biomaterials.

  9. Microbial sphingomyelinase induces RhoA-mediated reorganization of the apical brush border membrane and is protective against invasion.

    Science.gov (United States)

    Saslowsky, David E; Thiagarajah, Jay R; McCormick, Beth A; Lee, Jean C; Lencer, Wayne I

    2016-04-01

    The apical brush border membrane (BBM) of intestinal epithelial cells forms a highly structured and dynamic environmental interface that serves to regulate cellular physiology and block invasion by intestinal microbes and their products. How the BBM dynamically responds to pathogenic and commensal bacterial signals can define intestinal homeostasis and immune function. We previously found that in model intestinal epithelium, the conversion of apical membrane sphingomyelin to ceramide by exogenous bacterial sphingomyelinase (SMase) protected against the endocytosis and toxicity of cholera toxin. Here we elucidate a mechanism of action by showing that SMase induces a dramatic, reversible, RhoA-dependent alteration of the apical cortical F-actin network. Accumulation of apical membrane ceramide is necessary and sufficient to induce the actin phenotype, and this coincides with altered membrane structure and augmented innate immune function as evidenced by resistance to invasion by Salmonella. PMID:26864627

  10. Preparation and characterization of optical-functional diblock copolymer brushes on hollow sphere surface via atom transfer radical polymerization

    International Nuclear Information System (INIS)

    The optical-functional poly(methyl methacrylate)-block-Tb complex diblock copolymer brushes grafted from hollow sphere surface via atom transfer radical polymerization were investigated in this work. A sufficient amount of azo initiator was introduced onto hollow sphere surface firstly. Then the monomer methyl methacrylate was polymerized via surface-initiated reverse atom transfer radical polymerization using azo group modified hollow sphere as initiator. Following, the poly(methyl methacrylate) modified hollow sphere was used as maroinitiator for surface-initiated atom transfer radical polymerization of Tb complex. The samples were characterized by Fourier transform infrared spectroscopy, hydrogen nuclear magnetic resonance, gel permeation chromatographer and transmission electron microscopy, respectively. The results indicated that the poly(methyl methacrylate) had grafted from hollow sphere surface and the average diameter of hollow core was about 1 μm. The optical properties of the poly(methyl methacrylate)-block-Tb copolymer modified hollow sphere were also reported.

  11. Nanostructure of polymer monolayer and polyelectrolyte brush at air/water interface by X-ray and neutron reflectometry

    CERN Document Server

    Matsuoka, H; Matsumoto, K

    2003-01-01

    The nanostructure of amphiphilic diblock copolymer monolayer on water was directly investigated by in situ X-ray and neutron reflectivity techniques. The diblock copolymer consists of polysilacyclobutane, which is very flexible, as a hydrophobic block and polymethacrylic acid, an anionic polymer, as a hydrophilic block. The polymers with shorter hydrophilic segment formed a very smooth and uniform monolayer with hydrophobic layer on water and dense hydrophilic layer under the water. But the longer hydrophilic segment polymer formed three-layered monolayer with polyelectrolyte brush in addition to hydrophobic and dense hydrophilic layers. The dense hydrophilic layer is thought to be formed to avoid a contact between hydrophobic polymer layer and water. Its role is something like a 'carpet'. An additional interesting information is that the thickness of the 'carpet layer' is almost 15A, independent the surface pressure and hydrophilic polymer length. Highly quantitative information was obtained about the nanost...

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

    Science.gov (United States)

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

    2013-12-01

    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. PMID:24129356

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

    DEFF Research Database (Denmark)

    Danielsen, E M

    1992-01-01

    enzymes. In pulse-labeled mucosal explants, complete synthesis of the polypeptide chains of aminopeptidase N and sucrase-isomaltase required about 2 and 4 min, respectively, whereas maximal antiserum precipitation was acquired with half-times of 4-5 and 8 min, respectively. Fructose, which induces a...... posttranslational process. In the presence of fructose, not only the malglycosylated forms but also the electrophoretically normal, high-mannose-glycosylated form of the brush border enzymes were retained in the endoplasmic reticulum and proteolytically degraded. The results obtained demonstrate an intimate...... interrelationship between glycosylation and polypeptide folding in the synthesis of membrane glycoproteins and, more specifically, indicate that the timing of these two early biosynthetic events is essential for correct polypeptide folding....

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

    Directory of Open Access Journals (Sweden)

    Sarah V Consonni

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

  15. Fluorometric Measurement of Individual Stomata Activity and Transpiration via a “Brush-on”, Water-Responsive Polymer

    Science.gov (United States)

    Seo, Minjeong; Park, Dong-Hoon; Lee, Chan Woo; Jaworski, Justyn; Kim, Jong-Man

    2016-01-01

    Much of atmospheric water originates from transpiration, the process by which plants release H2O from pores, known as stomata, that simultaneously intake CO2 for photosynthesis. Controlling stomatal aperture can regulate the extent of water transport in response to dynamic environmental factors including osmotic stress, temperature, light, and wind. While larger leaf regions are often examined, the extent of water vapor release from individual stomata remains unexplored. Using a “brush-on” sensing material, we can now assess transpiration using a water-responsive, polydiacetylene-based coating on the leaves surfaces. By eliciting a fluorometric signal to passing water vapor, we obtained information regarding the activity of individual stomata. In this demonstration, our results prove that this coating can identify the proportion of active stomata and the extent of transpirational diffusion of water in response to different conditions. PMID:27578430

  16. Fluorometric Measurement of Individual Stomata Activity and Transpiration via a "Brush-on", Water-Responsive Polymer.

    Science.gov (United States)

    Seo, Minjeong; Park, Dong-Hoon; Lee, Chan Woo; Jaworski, Justyn; Kim, Jong-Man

    2016-01-01

    Much of atmospheric water originates from transpiration, the process by which plants release H2O from pores, known as stomata, that simultaneously intake CO2 for photosynthesis. Controlling stomatal aperture can regulate the extent of water transport in response to dynamic environmental factors including osmotic stress, temperature, light, and wind. While larger leaf regions are often examined, the extent of water vapor release from individual stomata remains unexplored. Using a "brush-on" sensing material, we can now assess transpiration using a water-responsive, polydiacetylene-based coating on the leaves surfaces. By eliciting a fluorometric signal to passing water vapor, we obtained information regarding the activity of individual stomata. In this demonstration, our results prove that this coating can identify the proportion of active stomata and the extent of transpirational diffusion of water in response to different conditions. PMID:27578430

  17. Chain dimensions in free and immobilized brush states of polysulfobetaine in aqueous solution at various salt concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Terayama, Y; Arita, H; Ishikawa, T; Takahara, A [Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0385 (Japan); Kikuchi, M; Mitamura, K; Kobayashi, M [JST, ERATO Takahara Soft Interfaces Project, 744 Motooka, Nishi-ku, Fukuoka 819-0385 (Japan); Yamada, N L, E-mail: takahara@cstf.kyushu-u.ac.jp [Neutron Science Laboratory, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)

    2011-01-01

    The chain dimensions of free and immobilized polysulfobetaine in aqueous solution at various salt concentrations were investigated by size-exclusion chromatography with multiangle light scattering and neutron reflectivity measurement, respectively. The dependence of the z-average mean square radius of gyration ({sub z}{sup 1/2}) on the weight-average molecular weight (M{sub w}) of free poly(3-(N-2-methacryloyloxyethyl-N,N-dimethyl)ammonatopropanesulfo-nate) (MAPS) in aqueous solution at salt concentrations of 74, 100, 200, and 500 mM was described by the perturbed wormlike chain model using the chain stiffness parameter {lambda}{sup -1} the molar mass per unit contour length ML, and the excluded volume effect B. B increased from 0 to 1.8 nm with increasing salt concentration to 500 mM due to the screening of attractive electrostatic interaction between ammonium cations and sulfonyl anions by salt ions. The swollen structure of the poly(MAPS) brush in D{sub 2}O changed from a shrunken state to a relatively extended state with increasing salt concentration from 0 to 500 mM NaCl/D{sub 2}O solution. The thickness of the swollen poly(MAPS) brush in 500 mM NaCl/D{sub 2}O was 9.0 times greater than 2{sub z}{sup 1/2} of free poly(MAPS) due to high osmotic pressure generated by the excluded volume effect of densely grafted polymer chains.

  18. Electricity derivatives

    CERN Document Server

    Aïd, René

    2015-01-01

    Offering a concise but complete survey of the common features of the microstructure of electricity markets, this book describes the state of the art in the different proposed electricity price models for pricing derivatives and in the numerical methods used to price and hedge the most prominent derivatives in electricity markets, namely power plants and swings. The mathematical content of the book has intentionally been made light in order to concentrate on the main subject matter, avoiding fastidious computations. Wherever possible, the models are illustrated by diagrams. The book should allow prospective researchers in the field of electricity derivatives to focus on the actual difficulties associated with the subject. It should also offer a brief but exhaustive overview of the latest techniques used by financial engineers in energy utilities and energy trading desks.

  19. Electricity futures

    OpenAIRE

    Falbo P; Felletti, D; S. De Stefani

    2016-01-01

    This chapter describes forwards and futures for electricity currently traded in Europe and other markets. Due to the non-storability of electricity, spot prices are highly dependent on local supply and demand conditions, business activity, and weather conditions. Seasonality is also very strong during the day (peak versus off-peak hours), during the week, and during cold and hot seasons. As a consequence, liquidity is low and the day-to-day volatility is much higher than in financial ma...

  20. Synthesis of densely grafted copolymers with tert-butyl methacrylate/2-(dimethylamino ethyl) methacrylate side chains as precursors for brush polyelectrolytes and polyampholytes

    Energy Technology Data Exchange (ETDEWEB)

    Gromadzki, Daniel, E-mail: d_grom@interia.pl [Department of Polymer Chemistry, Vilnius University, Naugarduko 24, LT-03225 Vilnius (Lithuania); Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, 162 06 Prague (Czech Republic); Stepanek, Petr [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, 162 06 Prague (Czech Republic); Makuska, Ricardas [Department of Polymer Chemistry, Vilnius University, Naugarduko 24, LT-03225 Vilnius (Lithuania)

    2013-01-15

    Methacrylate-based densely grafted copolymers were synthesized by atom transfer radical polymerization (ATRP) and activators generated by electron transfer for atom transfer radical polymerization (AGET ATRP) techniques. The linear poly(2-(2-bromoisobutyryloxy)ethyl methacrylate) PBIEM prepared by ATRP served as a macroinitiator backbone. The 'grafting from' strategy was used to initiate polymerization of tert-butyl methacrylate (tBuMA) from PBIEM under ATRP and/or AGET ATRP conditions yielding densely grafted copolymers PBIEM-graft-P(tBuMA). The low polydispersity indices (PDI) of the synthesized brushes evidenced by SEC analysis were consistent with a controlled/living radical polymerization (CLRP) mechanism. The chlorine-terminated PBIEM-graft-P(tBuMA)-Cl macroinitiators were subsequently employed for chain extension with 2-(dimethylamino ethyl) methacrylate (DMAEMA) yielding densely grafted copolymers with diblock copolymer side chains PBIEM-graft-P(tBuMA)-block-PDMAEMA. Further, PBIEM macroinitiator was used to initiate the copolymerization of a binary mixture of tBuMA and DMAEMA through both ATRP and AGET ATRP initiating systems, yielding densely grafted copolymers with statistical distribution of the side chains. The reactivity ratios for random graft copolymerization of tBuMA and DMAEMA from PBIEM backbone established by three different methods (Finemann-Ross, Kelen-Tuedoes and Error-in-Variable) did not substantially differ from literature values for conventional free-radical copolymerization of the same monomers. Polyampholyte brushes with PMAA-stat-PDMAEMA side chains were eventually synthesized by hydrolysis of the shielding tert-butyl groups. -- Graphical abstract: Synthesis of dense polyampholyte brushes by ATRP. A: synthesis of macroinitiator PBIEM; B: graft copolymerization of tBuMA and DMAEMA from PBIEM and hydrolysis of tBuMA units. Highlights: Black-Right-Pointing-Pointer tBuMA/DMAEMA based densely grafted brushes were prepared by ATRP