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Sample records for active polymer gel

  1. Active Polymer Gel Actuators

    Directory of Open Access Journals (Sweden)

    Shuji Hashimoto

    2010-01-01

    Full Text Available Many kinds of stimuli-responsive polymer and gels have been developed and applied to biomimetic actuators or artificial muscles. Electroactive polymers that change shape when stimulated electrically seem to be particularly promising. In all cases, however, the mechanical motion is driven by external stimuli, for example, reversing the direction of electric field. On the other hand, many living organisms can generate an autonomous motion without external driving stimuli like self-beating of heart muscles. Here we show a novel biomimetic gel actuator that can walk spontaneously with a wormlike motion without switching of external stimuli. The self-oscillating motion is produced by dissipating chemical energy of oscillating reaction. Although the gel is completely composed of synthetic polymer, it shows autonomous motion as if it were alive.

  2. Active Polymer Gel Actuators

    OpenAIRE

    Shuji Hashimoto; Ryo Yoshida; Yusuke Hara; Shingo Maeda

    2010-01-01

    Many kinds of stimuli-responsive polymer and gels have been developed and applied to biomimetic actuators or artificial muscles. Electroactive polymers that change shape when stimulated electrically seem to be particularly promising. In all cases, however, the mechanical motion is driven by external stimuli, for example, reversing the direction of electric field. On the other hand, many living organisms can generate an autonomous motion without external driving stimuli like self-beating of he...

  3. Design of electro-active polymer gels as actuator materials

    Science.gov (United States)

    Popovic, Suzana

    Smart materials, alternatively called active or adaptive, differ from passive materials in their sensing and activation capability. These materials can sense changes in environment such as: electric field, magnetic field, UV light, pH, temperature. They are capable of responding in numerous ways. Some change their stiffness properties (electro-rheological fluids), other deform (piezos, shape memory alloys, electrostrictive materials) or change optic properties (electrochromic polymers). Polymer gels are one of such materials which can change the shape, volume and even optical properties upon different applied stimuli. Due to their low stiffness property they are capable of having up to 100% of strain in a short time, order of seconds. Their motion resembles the one of biosystems, and they are often seen as possible artificial muscle materials. Despite their delicate nature, appropriate design can make them being used as actuator materials which can form controllable surfaces and mechanical switches. In this study several different groups of polymer gel material were investigated: (a) acrylamide based gels are sensitive to pH and electric field and respond in volume change, (b) polyacrylonitrile (PAN) gel is sensitive to pH and electric field and responds in axial strain and bending, (c) polyvinylalcohol (PVA) gel is sensitive to electric field and responds in axial strain and bending and (d) perfluorinated sulfonic acid membrane, Nafion RTM, is sensitive to electric field and responds in bending. Electro-mechanical and chemo-mechanical behavior of these materials is a function of a variety of phenomena: polymer structure, affinity of polymer to the solvent, charge distribution within material, type of solvent, elasticity of polymer matrix, etc. Modeling of this behavior is a task aimed to identify what is driving mechanism for activation and express it in a quantitative way in terms of deformation of material. In this work behavior of the most promising material as

  4. "JCE" Classroom Activity Connections: NaCl or CaCl[subscript 2], Smart Polymer Gel Tells More

    Science.gov (United States)

    Chen, Yueh-Huey; Lin, Jia-Ying; Wang, Yu-Chen; Yaung, Jing-Fun

    2010-01-01

    This classroom activity connection demonstrates the differences between the effects of NaCl (a salt of monovalent metal ions) and CaCl[subscript 2] (a salt of polyvalent metal ions) on swollen superabsorbent polymer gels. Being ionic compounds, NaCl and CaCl[subscript 2] both collapse the swollen polymer gels. The gel contracted by NaCl reswells…

  5. Dynamics of self-oscillating cilia designed from active polymer gels

    Science.gov (United States)

    Dayal, Pratyush; Bhattacharya, Amitabh; Kuksenok, Olga; Balazs, Anna C.

    2012-02-01

    Using theory and simulations, we design active synthetic surfaces which are capable of replicating functionalities of biological cilia. In order to design such exquisite biomimetic systems we harness unique properties of polymer gels that undergo photosensitive Belousov-Zhabotinsky (BZ) reaction. Powered by internalized BZ reaction these polymer gels swell and de-swell autonomously by chemo-mechanical transduction and therefore are ideal materials for designing our system. In order to simulate the dynamics of the BZ cilia in surrounding fluid we have developed a nonlinear hybrid 3D model which captures elasto-dynamics of polymer gel and diffusive exchange of BZ reagents between the gel and the fluid. Here we show that the geometrical arrangement of cilia and the distribution of BZ activator in the fluid determine the dynamic response of the cilia. We further show that using light as an external stimulus we can sequentially modulate height of individual cilium and thereby create the ``piano effect''. Finally, we demonstrate that synchronized oscillations in the cilia result from the distribution of BZ-activator in the surrounding fluid. Our findings can be used to design active surfaces which can be remotely tuned depending upon the magnitude of external stimuli.

  6. Gel polymer electrolytes for batteries

    Science.gov (United States)

    Balsara, Nitash Pervez; Eitouni, Hany Basam; Gur, Ilan; Singh, Mohit; Hudson, William

    2014-11-18

    Nanostructured gel polymer electrolytes that have both high ionic conductivity and high mechanical strength are disclosed. The electrolytes have at least two domains--one domain contains an ionically-conductive gel polymer and the other domain contains a rigid polymer that provides structure for the electrolyte. The domains are formed by block copolymers. The first block provides a polymer matrix that may or may not be conductive on by itself, but that can soak up a liquid electrolyte, thereby making a gel. An exemplary nanostructured gel polymer electrolyte has an ionic conductivity of at least 1.times.10.sup.-4 S cm.sup.-1 at 25.degree. C.

  7. Sol-Gel Entrapped Levonorgestrel Antibodies: Activity and Structural Changes as a Function of Different Polymer Formats

    Directory of Open Access Journals (Sweden)

    Moran Shalev

    2011-02-01

    Full Text Available The paper describes development of a sol-gel based immunoaffinity method for the steroid hormone levonorgestrel (LNG and the effects of changes in the sol-gel matrix format on the activity of the entrapped antibodies (Abs and on matrix structure. The best sol-gel format for Ab entrapment was found to be a tetramethoxysilane (TMOS based matrix at a TMOS:water ratio of 1:8, containing 10% polyethylene glycol (PEG of MW 0.4 kDa. Addition of higher percentages of PEG or a higher MW PEG did not improve activity. No activity was obtained with a TMOS:water ratio of 1:12, most likely because of the very dense polymer that resulted from these polymerization conditions. Only minor differences in the non-specific binding were obtained with the various formats. TMOS was found to be more effective than tetrakis (2-hydroxyethylorthosilicate (THEOS for entrapment of anti-levonorgestrel (LNG Abs. However, aging the THEOS-based sol-gel for a few weeks at 4 °C stabilized the entrapped Abs and increased its binding capacity. Confocal fluorescent microscopy with fluorescein isothiocyanate (FITC labeled immunoglobulines (IgGs entrapped in the sol-gel matrix showed that the entrapped Abs were distributed homogenously within the gel. Scanning electron microscopy (SEM images have shown the diverse structures of the various sol-gel formats and precursors.

  8. Conductivity behaviour of polymer gel electrolytes: Role of polymer

    Indian Academy of Sciences (India)

    S S Sekhon

    2003-04-01

    Polymer is an important constituent of polymer gel electrolytes along with salt and solvent. The salt provides ions for conduction and the solvent helps in the dissolution of the salt and also provides the medium for ion conduction. Although the polymer added provides mechanical stability to the electrolytes yet its effect on the conductivity behaviour of gel electrolytes as well as the interaction of polymer with salt and solvent has not been conclusively established. The conductivity of lithium ion conducting polymer gel electrolytes decreases with the addition of polymer whereas in the case of proton conducting polymer gel electrolytes an increase in conductivity has been observed with polymer addition. This has been explained to be due to the role of polymer in increasing viscosity and carrier concentration in these gel electrolytes.

  9. Hybrid Materials of Polymer Gels with Surfactants

    Institute of Scientific and Technical Information of China (English)

    Hu Yan; Kaoru Tsujii

    2005-01-01

    @@ 1 Introduction Polymer gels have been extensively studied[1~17] since the discovery of volume phase-transition of a gel by Tanaka[1~5]. As a unique soft material, gels attract much attention and are tried to be applied for drug-delivery systgems[6], actuators or chemo-mechanical devices[7~9] and so on. In particular, controlled-release of small molecules from a gel is now a subject of special interest[10].

  10. Enhanced ultraviolet photocatalytic activity of Ag/ZnO nanoparticles synthesized by modified polymer-network gel method

    Science.gov (United States)

    Lu, Y. H.; Xu, M.; Xu, L. X.; Zhang, C. L.; Zhang, Q. P.; Xu, X. N.; Xu, S.; Ostrikov, K.

    2015-09-01

    Ag/ZnO nanoparticle (NP) heterostructures are synthesized through a modified polymer-network gel method in which glucose is added to the precursor solution to prevent the gel from drastically shrinking during drying of the aqueous solution. Structural and optical properties of the samples are characterized by a range of techniques including XRD, SEM, TEM, XPS, UV-Vis, and PL. The high-quality Ag-ZnO heterostructure is evidenced clearly by high-resolution TEM. The Ag/ZnO heterostructure nanocomposites exhibit a higher photocatalytic activity in the degradation of methyl orange than pure ZnO. Especially, Ag/ZnO NP heterostructures with the Ag/Zn molar ratio of 5:95 (sample ZA-5) show the highest degradation efficiency, which is 11 times higher compared with pure ZnO. The photoluminescence properties of the heterostructures and O defect states are studied to well explain the observed photocatalytic effects. ZA-5 also exhibits competitive photocatalytic activity for the degradation of other pollutant dyes such as Methylene blue and Rhodamine B compared with the recently reported techniques, while showing excellent catalyst photostability as well as offering simplicity and reliability.

  11. Enhanced ultraviolet photocatalytic activity of Ag/ZnO nanoparticles synthesized by modified polymer-network gel method

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Y. H.; Xu, M., E-mail: hsuming-2001@aliyun.com [Southwest University for Nationalities, Key Laboratory of Information Materials of Sichuan Province, School of Electrical and Information Engineering (China); Xu, L. X. [Nanyang Technological University, Plasma Sources and Applications Center, NIE (Singapore); Zhang, C. L.; Zhang, Q. P.; Xu, X. N. [Southwest University for Nationalities, Key Laboratory of Information Materials of Sichuan Province, School of Electrical and Information Engineering (China); Xu, S. [Nanyang Technological University, Plasma Sources and Applications Center, NIE (Singapore); Ostrikov, K., E-mail: kostya.ostrikov@qut.edu.au [Queensland University of Technology, Institute for Future Environments and School of Chemistry, Physics, and Mechanical Engineering (Australia)

    2015-09-15

    Ag/ZnO nanoparticle (NP) heterostructures are synthesized through a modified polymer-network gel method in which glucose is added to the precursor solution to prevent the gel from drastically shrinking during drying of the aqueous solution. Structural and optical properties of the samples are characterized by a range of techniques including XRD, SEM, TEM, XPS, UV–Vis, and PL. The high-quality Ag-ZnO heterostructure is evidenced clearly by high-resolution TEM. The Ag/ZnO heterostructure nanocomposites exhibit a higher photocatalytic activity in the degradation of methyl orange than pure ZnO. Especially, Ag/ZnO NP heterostructures with the Ag/Zn molar ratio of 5:95 (sample ZA-5) show the highest degradation efficiency, which is 11 times higher compared with pure ZnO. The photoluminescence properties of the heterostructures and O defect states are studied to well explain the observed photocatalytic effects. ZA-5 also exhibits competitive photocatalytic activity for the degradation of other pollutant dyes such as Methylene blue and Rhodamine B compared with the recently reported techniques, while showing excellent catalyst photostability as well as offering simplicity and reliability.

  12. Electrochemical Study of Conductive Gel Polymer

    Institute of Scientific and Technical Information of China (English)

    Zhaohui Li; Jing Jiang; Gangtie Lei

    2005-01-01

    @@ 1Introduction Conventional ion-conducting polymer consists of electrolyte salt and polymer matrix, so-called salt-inpolymer. It possesses lower conductivity because the migration of ions depends on the motion of polymer segmental. To increase the ionic conductivity, a kind of gel polymer film (GPF) was prepared by in situ polymerization of methyl methacrylate (MMA) monomer in room-temperature ionic liquid(RTIL), 1-butyl-3-methylimidazolium hexafluorophosphate (BMIPF6). Due to immeasurably low vapor pressure, high ionic conductivity, and greater thermal and electrochemical stability, BMIPF6 is suitable electrolyte salts for ion-conducting polymer.

  13. Conducting polymer electrodes for gel electrophoresis.

    Science.gov (United States)

    Bengtsson, Katarina; Nilsson, Sara; Robinson, Nathaniel D

    2014-01-01

    In nearly all cases, electrophoresis in gels is driven via the electrolysis of water at the electrodes, where the process consumes water and produces electrochemical by-products. We have previously demonstrated that π-conjugated polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT) can be placed between traditional metal electrodes and an electrolyte to mitigate electrolysis in liquid (capillary electroosmosis/electrophoresis) systems. In this report, we extend our previous result to gel electrophoresis, and show that electrodes containing PEDOT can be used with a commercial polyacrylamide gel electrophoresis system with minimal impact to the resulting gel image or the ionic transport measured during a separation.

  14. Conducting polymer electrodes for gel electrophoresis.

    Directory of Open Access Journals (Sweden)

    Katarina Bengtsson

    Full Text Available In nearly all cases, electrophoresis in gels is driven via the electrolysis of water at the electrodes, where the process consumes water and produces electrochemical by-products. We have previously demonstrated that π-conjugated polymers such as poly(3,4-ethylenedioxythiophene (PEDOT can be placed between traditional metal electrodes and an electrolyte to mitigate electrolysis in liquid (capillary electroosmosis/electrophoresis systems. In this report, we extend our previous result to gel electrophoresis, and show that electrodes containing PEDOT can be used with a commercial polyacrylamide gel electrophoresis system with minimal impact to the resulting gel image or the ionic transport measured during a separation.

  15. Actuator device utilizing a conductive polymer gel

    Science.gov (United States)

    Chinn, Douglas A.; Irvin, David J.

    2004-02-03

    A valve actuator based on a conductive polymer gel is disclosed. A nonconductive housing is provided having two separate chambers separated by a porous frit. The conductive polymer is held in one chamber and an electrolyte solution, used as a source of charged ions, is held in the second chamber. The ends of the housing a sealed with a flexible elastomer. The polymer gel is further provide with electrodes with which to apply an electrical potential across the gel in order to initiate an oxidation reaction which in turn drives anions across the porous frit and into the polymer gel, swelling the volume of the gel and simultaneously contracting the volume of the electrolyte solution. Because the two end chambers are sealed the flexible elastomer expands or contracts with the chamber volume change. By manipulating the potential across the gel the motion of the elastomer can be controlled to act as a "gate" to open or close a fluid channel and thereby control flow through that channel.

  16. Rheological properties of polymer micro-gel dispersions

    Institute of Scientific and Technical Information of China (English)

    Dong Zhaoxia; Li Yahua; Lin Meiqin; Li Mingyuan

    2009-01-01

    The influence of swelling time, temperature, NaCI concentration and polymer micro-gel concentration on rheological properties of polymer micro-gel dispersions was studied by using a HAAKE rheometer. The results showed that with increasing swelling time and NaCI concentration, the polymer micro-gel dispersions changed from a shear-thickening fluid to a Newtonian fluid. The polymer micro- gel dispersion show shear-thinning in non-saline water. At higher swelling temperature, the time of the polymer micro-gel dispersion showing shear-thickening was shorter. With increasing polymer micro-gel concentration, the dispersion changed from shear-thickening to shear-thinning.

  17. Drying and shrinkage of polymer gels

    Directory of Open Access Journals (Sweden)

    S. S. Waje

    2005-06-01

    Full Text Available The polymer hydrogel was synthesized by photo-polymerization process (UV light, 60 ºC in presence of Photo-initiator (IrgacureR and Cross-linker (NN'-methylene bisacrylamide; MBAM. In the present work, the drying of polymer hydrogel was carried out to study the effect of temperature, gel-sheet thickness, monomer ratio of acryl acid to acrylamide (AA/AM, concentration of MBAM and quantity of monomers. A correlation has been developed for modified sheet thickness as a function of contraction coefficient and degree of drying. Effective diffusivity was estimated from Fickian-diffusive model considering modified sheet thickness and was found to be in the range of 1.1 ´ 10-10-5.93 ´ 10-10 m²/s. The activation energy obtained using Arrhenius type equation was found to be in the range of 2979-10737 kJ/kmol H2O. The drying behavior shows an initial shoot-up in drying rate followed by constant rate and two falling rate periods.

  18. Porosity Governs Normal Stresses in Polymer Gels.

    Science.gov (United States)

    de Cagny, Henri C G; Vos, Bart E; Vahabi, Mahsa; Kurniawan, Nicholas A; Doi, Masao; Koenderink, Gijsje H; MacKintosh, F C; Bonn, Daniel

    2016-11-18

    When sheared, most elastic solids including metals, rubbers, and polymer gels dilate perpendicularly to the shear plane. This behavior, known as the Poynting effect, is characterized by a positive normal stress. Surprisingly, fibrous biopolymer gels exhibit a negative normal stress under shear. Here we show that this anomalous behavior originates from the open-network structure of biopolymer gels. Using fibrin networks with a controllable pore size as a model system, we show that the normal-stress response to an applied shear is positive at short times, but decreases to negative values with a characteristic time scale set by pore size. Using a two-fluid model, we develop a quantitative theory that unifies the opposite behaviors encountered in synthetic and biopolymer gels.

  19. Polymer and Polymer Gel of Liquid Crystalline Semiconductors

    Institute of Scientific and Technical Information of China (English)

    Teppei Shimakawa; Naoki Yoshimoto; Jun-ichi Hanna

    2004-01-01

    It prepared a polymer and polymer gel of a liquid crystalline (LC) semiconductor having a 2-phenylnaphthalene moiety and studied their charge carrier transport properties by the time-of-flight technique. It is found that polyacrylate having the mesogenic core moiety of 2-phenylnaphtalene (PNP-acrylate) exhibited a comparable mobility of 10-4cm2/Vs in smectic A phase to those in smectic A (SmA) phase of small molecular liquid crystals with the same core moiety, e.g., 6-(4'-octylphenyl)- 2-dodecyloxynaphthalene (8-PNP-O12), and an enhanced mobility up to 10-3cm2/Vs in the LC-glassy phase at room temperature, when mixed with a small amount of 8-PNP-O12. On the other hand, the polymer gel consisting of 20 wt %-hexamethylenediacrylate (HDA)-based cross-linked polymer and 8-PNP-O12 exhibited no degraded mobility when cross-linked at the mesophase. These results indicate that the polymer and polymer composite of liquid crystalline semiconductors provide us with an easy way to realize a quality organic semiconductor thin film for the immediate device applications.

  20. SURFACE DYNAMIC FRICTION OF POLYMER GELS

    Institute of Scientific and Technical Information of China (English)

    J.P.Gong; G.Kagata; Y.Iwasaki; Y.Osada

    2000-01-01

    The sliding friction of various kinds of hydrogels has been studied and it was found that the frictional behaviors of the hydrogels do not conform to Amonton's law F =μW which well describes the friction of solids. The frictional force and its dependence on the load are quite different depending on the chemical structures of the gels, surface properties of the opposing substrates, and the measurement condition. The gel friction is explained in terms of interfacial interaction, either attractive or repulsive, between the polymer chain and the solid surface. According to this model, the friction is ascribed to the viscous flow of solvent at the interface in the repulsive case. In the attractive case, the force to detach the adsorbing chain from the substrate appears as friction. The surface adhesion between glass particles and gels measured by AFM showed a good correlation with the friction, which supported the repulsion-adsorption model proposed by the authors.

  1. Active Gel Model of Amoeboid Cell Motility

    CERN Document Server

    Callan-Jones, A C

    2013-01-01

    We develop a model of amoeboid cell motility based on active gel theory. Modeling the motile apparatus of a eukaryotic cell as a confined layer of finite length of poroelastic active gel permeated by a solvent, we first show that, due to active stress and gel turnover, an initially static and homogeneous layer can undergo a contractile-type instability to a polarized moving state in which the rear is enriched in gel polymer. This agrees qualitatively with motile cells containing an actomyosin-rich uropod at their rear. We find that the gel layer settles into a steadily moving, inhomogeneous state at long times, sustained by a balance between contractility and filament turnover. In addition, our model predicts an optimal value of the gel-susbstrate adhesion leading to maximum layer speed, in agreement with cell motility assays. The model may be relevant to motility of cells translocating in complex, confining environments that can be mimicked experimentally by cell migration through microchannels.

  2. Soluble polymers in sol-gel silica

    Science.gov (United States)

    Beaudry, Christopher Laurent

    In the last few years, the inherent versatility of sol-gel processing has led to a significant research effort on inorganic/organic materials. One method of incorporating an organic phase into sol-gel silica is dissolving an organic polymer in a tetraethylorthosilicate (TEOS) solution, followed by in situ polymerization of silica in the presence of organic polymer. The first part of the study involved the development of a two-step (acid-base) synthesis procedure to allow systematic control of acidity in TEOS solutions. With this procedure, it was possible to increase the pH of the TEOS solution while correlating the acidity and properties. The properties were the gelation time, syneresis rate, drying behavior, and xerogel pore structure, as determined by nitrogen sorption. Furthermore, controlling the acidity was shown to control the silica xerogel pore structure. In the second part of the study, the two-step procedure was used to synthesize silica/poly(ethylene glycol) (PEG), and silica/poly(vinyl acetate) (PVAc) composite materials. The content of organic polymer and the molecular weight were varied. The gelation time, the syneresis rate, the drying behavior, and the pore structure were determined for compositions with 10% PEG (M.W. 2,000), 5, 10, and 15% PEG (M.W. 3,400), and 10 and 25% PVAc (M.W. 83,000). Other compositions and molecular weights of PEG lead to sedimentation. In the PEG compositions, the tendency to phase separate was correlated with the effects of the processing variables on the segregation strength and polymerization rate. The PVAc compositions did not show any visible phase separation during processing, giving the composite xerogels an appearance similar to pure silica. The property differences between gels with PEG and gels with PVAc show the relative strength of the interactions with silica. Both polymers exhibit hydrogen bonding between the phases. In the case of PEG, hydrogen bonding between the ether oxygens of the polymer and silanol

  3. Branched Polymers for Enhancing Polymer Gel Strength and Toughness

    Science.gov (United States)

    2013-02-01

    of the gel through different toughening mechanisms, each required complicated processing not amenable to scale up limiting their broad utility...100 Pa – 10 kPa) to structural resins (G’ ~ >10 MPa). In particular, this approach will address the prohibitively low fracture toughness of soft...Mrozek, R. A.; Lenhart, J. L.; Lambeth, R. H.; Andzelm, J. W. Novel branched additives for polymer toughening , Patent Disclosure [S/N 61/645,286

  4. Antioxidant effect of green tea on polymer gel dosimeter

    Science.gov (United States)

    Samuel, E. J. J.; Sathiyaraj, P.; Deena, T.; Kumar, D. S.

    2015-01-01

    Extract from Green Tea (GTE) acts as an antioxidant in acrylamide based polymer gel dosimeter. In this work, PAGAT gel was used for investigation of antioxidant effect of GTE.PAGAT was called PAGTEG (Polyacrylamide green tea extract gel dosimeter) after adding GTE. Free radicals in water cause pre polymerization of polymer gel before irradiation. Polyphenols from GTE are highly effective to absorb the free radicals in water. THPC is used as an antioxidant in polymer gel dosimeter but here we were replaced it by GTE and investigated its effect by spectrophotometer. GTE added PAGAT samples response was lower compared to THPC added sample. To increase the sensitivity of the PAGTEG, sugar was added. This study confirmed that THPC was a good antioxidant for polymer gel dosimeter. However, GTE also can be used as an antioxidant in polymer gel if use less quantity (GTE) and add sugar as sensitivity enhancer.

  5. Stimuli responsive polymer gels for sensing applications

    OpenAIRE

    Kavanagh, Andrew

    2012-01-01

    This chapter (3) is based on simplifying the design template of an optical sensor through the multifunctionality imparted on it by an IL. The IL simplified polymer gel is termed an optode within this chapter as (a) it is prepared the same manner as optodes, (b) the IL performs many of the same functions as previous materials used in optode design and (c) the analyte or ion movement between the aqueous and organic phases follows the same convention for optodes. The 2-component optode membr...

  6. CURRENT COLLOIDAL DISPERSION GELS ARE NOT SUPERIOR TO POLYMER FLOODING

    Institute of Scientific and Technical Information of China (English)

    Seright Randy; Han Peihui; Wang Dongmei

    2006-01-01

    The suggestion that the colloidal-dispersion-gel (CDG) process is superior to normal polymer flooding is misleading and generally incorrect. Colloidal dispersion gels, in their present state of technological development, should not be advocated as an improvement to, or substitute for, polymer flooding. Gels made from aluminum-citrate crosslinked polyacrylamides can act as conventional gels and provide effective conformance improvement in treating some types of excess water production problems if sound scientific and engineering principles are respected.

  7. Stabilization of polymer gels against divalent ion-induced syneresis

    Energy Technology Data Exchange (ETDEWEB)

    Albonico, Paola; Lockhart, Thomas P. [Eniricerche SpA, San Donato, Milan (Italy)

    1997-07-15

    Polymer solutions and polymer gels are unstable to extended ageing in divalent cation-rich brines at elevated temperature. This paper shows that low-molecular-weight compounds that complex strongly with Ca{sup 2+} and Mg{sup 2+} are capable of neutralizing their destabilizing influence on polymer solubility and of inhibiting the syneresis of crosslinked acrylamide polymer gels in hard brines. The solubility of the inhibitor-divalent ion complexes formed in hard brine at elevated temperature have also been examined. The results obtained offer the possibility to extend significantly the upper temperature limit for the use of polyacrylamides and acrylamide copolymers in brines in both polymer flooding and polymer gel treatments

  8. New polymer gel dosimeters consisting of less toxic monomers with radiation-crosslinked gel matrix

    Science.gov (United States)

    Hiroki, A.; Yamashita, S.; Sato, Y.; Nagasawa, N.; Taguchi, M.

    2013-06-01

    New polymer gel dosimeters consisting of less toxic methacrylate-type monomers such as 2-hydroxymethyl methacrylate (HEMA) and polyethylene glycol 400 dimethacrylate (9G) with hydroxypropyl cellulose (HPC) gel were prepared. The HPC gels were obtained by using a radiation-induced crosslinking technique to be applied in a matrix instead of a gelatin, which is conventionally used in earlier dosimeters, for the polymer gel dosimeters. The prepared polymer gel dosimeters showed cloudiness by exposing to 60Co γ-ray, in which the cloudiness increased with the dose up to 10 Gy. At the same dose, the increase in the cloudiness appeared with increasing concentration of 9G. As a result of the absorbance measurement, it was found that the dose response depended on the composition ratio between HEMA and 9G.

  9. Radiological properties of MAGIC normoxic polymer gel dosimetry

    Science.gov (United States)

    Aljamal, M.; Zakaria, A.; Shamsuddin, S.

    2013-04-01

    For a polymer gel dosimeter to be of use in radiation dosimetry, it should display water-equivalent radiological properties. In this study, the radiological properties of the MAGIC (Methacrylic and Ascorbic acid in Gelatin Initiated by Copper) normoxic polymer gels were investigated. The mass density (ρ) was determined based on Archimedes' principle. The weight fraction of elemental composition and the effective atomic number (Zeff) were calculated. The electron density was also measured with 90° scattering angle at room temperature. The linear attenuation coefficient (μ) of unirradiated gel, irradiated gel, and water were determined using Am-241 based on narrow beam geometry. Monte Carlo simulation was used to calculate the depth doses response of MAGIC gel and water for 6MV photon beam. The weight fractions of elements composition of MAGIC gel were close to that for water. The mass density was found to be 1027 ± 2 kg m-3, which is also very close to mass density of muscle tissue (1030 kg m-3) and 2.7% higher than that of water. The electron density (ρe) and atomic number (Zeff) were found to be 3.43 × 1029 e m-3 and 7.105, respectively. The electron density measured was 2.6% greater than that for water. The atomic number was very close to that for water. The prepared MAGIC gel was found to be water equivalent based on the study of element composition, mass density, electron density and atomic number. The linear attenuation coefficient of unirradiated gel was very close to that of water. The μ of irradiated gel was found to be linear with dose 2-40 Gy. The depth dose response for MAGIC gel from a 6 MV photon beam had a percentage dose difference to water of less than 1%. Therefore it satisfies the criteria to be a good polymer gel dosimeter for radiotherapy.

  10. Modelling of the inhomogeneous interior of polymer gels

    Science.gov (United States)

    Shew, Chwen-Yang; Iwaki, Takafumi

    2006-04-01

    A simple model has been investigated to elucidate the mean squared displacement (MSD) of probe molecules in cross-linked polymer gels. In the model, we assume that numerous cavities distribute in the inhomogeneous interior of a gel, and probe molecules are confined within these cavities. The individual probe molecules trapped in a gel are treated as Brownian particles confined to a spherical harmonic potential. The harmonic potential is chosen to model the effective potential experienced by the probe particle in the cavity of a gel. Each field strength is corresponding to the characteristic of one type of effective cavity. Since the statistical distribution of different effective cavity sizes is unknown, several distribution functions are examined. Meanwhile, the calculated averaged MSDs are compared to the experimental data by Nisato et al (2000 Phys. Rev. E 61 2879). We find that the theoretical results of the MSD are sensitive to the shape of the distribution function. For low cross-linked gels, the best fit is obtained when the interior cavities of a gel follow a bimodal distribution. Such a result may be attributed to the presence of at least two distinct classes of cavity in gels. For high cross-linked gels, the cavities in the gel can be depicted by a single-modal uniform distribution function, suggesting that the range of cavity sizes becomes smaller. These results manifest the voids inside a gel, and the shape of distribution functions may provide the insight into the inhomogeneous interior of a gel.

  11. Ionic conductivity through thermoresponsive polymer gel: ordering matters.

    Science.gov (United States)

    Soni, Saurabh S; Fadadu, Kishan B; Gibaud, Alain

    2012-01-10

    Thermoreversible polymer gel has been prepared using PEO-PPO-PEO block copolymer (Pluronic F77) which self-assembles into different microcrystalline phases like cubic, 2D-hexagonal, and lamellar. Addition of electrolyte (LiI/I(2)) converts the gel into a polymer gel electrolyte (PGE) which exhibits microphase-dependent ionic conductivity. The crystalline phases have been identified by SAXS as a function of the polymer concentration. It is found that the optimum value for the ionic conductivity (≈1 × 10(-3) S x cm(-1)) is achieved in the Im3m phase due to faster diffusion of ions through the 3D-interconnected micellar nanochannels. This fact is further supported by FTIR study, ionic transference number, and diffusion coefficient measurements.

  12. Morphology of Polyvinylidene Fluoride Based Gel Polymer Electrolytes

    Institute of Scientific and Technical Information of China (English)

    田立颖; 黄小彬; 唐小真

    2004-01-01

    Two series of polyvinylidene fluoride (PVDF) based gel polymer electrolytes, with different LiClO4 or propylene carbonate (PC) content, were prepared and analyzed by infrared spectrometer, differential scanning calorimetry, scanning electron microscope and complex impedance spectrometer. The results show that there are great interactions between PVDF, PC and lithium cations. Both LiClO4 and PC content lead to evident change of the morphology of the gel polymer electrolytes. The content of LiClO4 and PC also influences the ionic conductivity of the samples,and an ionic conductivity of above 10-3S·cm-1 can be reached at room temperature.

  13. PMMA-based Gel Polymer Electrolytes with Crosslinking Network

    Institute of Scientific and Technical Information of China (English)

    H.P. Zhang; Y. P. Wu; H. Q. Wu; M. Sun

    2005-01-01

    @@ 1Introduction The lithium-ion battery has a good rate capability and low-temperature performance, but its safety is relatively low due to the possibility of leakage of liquid electrolyte. The use of a solid or gel type electrolyte can lower the probability of leakage liquid electrolyte, and the electrochemical performance of gel electrolyte doesn't decrease so markedly as the solid electrolyte. Now, new types of advanced lithium-ion battery with gel polymer electrolytes are under developing which can be used in the future.

  14. Nonlinear dynamics of self-oscillating polymer gels

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Self-oscillating polymer gels driven by Belousov-Zhabotinsky (BZ) chemical reaction are a new class of functional gels that have a wide range of potential applications (e.g., autonomously functioning membranes, actuate artificial muscles). However, the precise control of these gels has been an issue due to limited investigations of the influences of key system parameters on the characteristics of BZ gels. To address this deficiency, we studied the self-oscillating behavior of BZ gels using the nonline-ar dynamics theory and an Oregonator-like model, with focus placed upon the influences of various system parameters. The analysis of the oscillation phase indicated that the dynamic response of BZ gels represents the classical limit cycle oscillation. We then investigated the characteristics of the limit cycle oscillation and quantified the influences of key parameters (i.e., ini-tial reactant concentration, oxidation and reduction rate of catalyst, and response coefficient) on the self-oscillating behavior of BZ gels. The results demonstrated that sustained limit cycle oscillation of BZ gels can be achieved only when these key pa-rameters meet certain requirements, and that the pattern, period and amplitude of the oscillation are significantly influenced by these parameters. The results obtained in this study could enable the controlled self-oscillation of BZ gels system. This has several potential applications such as controlled drug delivery, miniature peristaltic pumps and microactuators.

  15. Carbon beam dosimetry using VIP polymer gel and MRI

    DEFF Research Database (Denmark)

    Kantemiris, I; Petrokokkinos, L; Angelopoulos, A

    2009-01-01

    VIP polymer gel dosimeter was used for Carbon ion beam dosimetry using a 150 MeV/n beam with 10 Gy plateau dose and a SOBP irradiation scheme with 5 Gy Bragg peak dose. The results show a decrease by 8 mm in the expected from Monte Carlo simulation range in water, suggesting that the dosimeter...

  16. Rheology and Relaxation Timescales of ABA Triblock Polymer Gels

    Science.gov (United States)

    Peters, Andrew; Lodge, Timothy

    When dissolved in a midblock selective solvent, ABA polymers form gels composed of aggregated end block micelles bridged by the midblocks. While much effort has been devoted to the study of the structure of these systems, the dynamics of these systems has received less attention. We examine the underlying mechanism of shear relaxation of ABA triblock polymer gels, especially as a function of chain length, composition, and concentration. Recent work using time-resolved small-angle neutron scattering of polystyrene (PS)-block-poly(ethylene-alt-propylene) (PEP) in squalane has elucidated many aspects of the dynamics of diblock chain exchange. By using rheology to study bulk relaxation phenomena of the triblock equivalent, PS-PEP-PS, we apply the knowledge gained from the chain exchange studies to bridge the gap between the molecular and macroscopic relaxation phenomena in PS-PEP-PS triblock gels.

  17. Non-aqueous gel polymer electrolyte with phosphoric acid ester and its application for quasi solid-state supercapacitors

    OpenAIRE

    Latoszyńska, Anna A.; Zukowska, Grażyna Zofia; Rutkowska, Iwona A.; Taberna, Pierre-Louis; Simon, Patrice; Kulesza, Pawel J.; Wieczorek, Władysław

    2015-01-01

    International audience; A mechanically-stable non-aqueous proton-conducting gel polymer electrolyte that is based on methacrylate monomers, is considered here for application in solid-state type supercapacitors. An electrochemical cell using activated carbon as active materials and the new gel polymer electrolyte has been characterized at room temperature using cyclic voltammetry, galvanostatic charge–discharge cycle tests as well as impedance spectroscopy. The use of phosphoric acid ester (i...

  18. Correlation between ionic conductivity and fluidity of polymer gel electrolytes containing NH4CF3SO3

    Indian Academy of Sciences (India)

    Harinder Pal Singh; Rajiv Kumar; S S Sekhon

    2005-08-01

    Nonaqueous polymer gel electrolytes containing ammonium triflate (NH4CF3SO3) and dimethylacetamide (DMA) with polymethylmethacrylate (PMMA) as the gelling polymer have been synthesized which show high value of conductivity (∼ 10-2 S/cm) at 25°C. The conductivity of polymer gel electrolytes containing different concentrations of NH4CF3SO3 shows a small decrease with the addition of PMMA and this has been correlated with the variation of fluidity of these gel electrolytes. The small decrease in conductivity with PMMA addition shows that polymer plays the role of stiffener and this is supported by FTIR results which also indicates the absence of any active interaction between polymer and NH4CF3SO3 in these gel electrolytes.

  19. Structure and Properties of Polysaccharide Based BioPolymer Gels

    Science.gov (United States)

    Prud'Homme, Robert K.

    2000-03-01

    Nature uses the pyranose ring as the basic building unit for a wideclass of biopolymers. Because of their biological origin these biopolymers naturally find application as food additives, rheology modifiers. These polymers range from being rigid skeletal material, such as cellulose that resist dissolution in water, to water soluble polymers, such as guar or carrageenan. The flexibility of the basic pyranose ring structure to provide materials with such a wide range of properties comes from the specific interactions that can be engineered by nature into the structure. We will present several examples of specific interactions for these systems: hydrogen bonding, hydrophobic interactions, and specific ion interactions. The relationship between molecular interations and rheology will be emphasized. Hydrogen bonding mediated by steric interference is used to control of solubility of starch and the rheology of guar gels. A more interesting example is the hydrogen bonding induced by chemical modification in konjac glucomannan that results in a gel that melts upon cooling. Hydrogen bonding interactions in xanthan lead to gel formation at very low polymer concentrations which is a result of the fine tuning of the polymer persistence length and total contour length. Given the function of xanthan in nature its molecular architecture has been optimized. Hydrophobic interactions in methylcellulose show a reverse temperature dependence arising from solution entropy. Carrageenan gelation upon the addition of specific cations will be addressed to show the interplay of polymer secondary structure on chemical reactivity. And finally the cis-hydroxyls on galactomannans permit crosslinking by a variety of metal ions some of which lead to "living gels" and some of which lead to permanently crosslinked networks.

  20. Preparation of a Star Network PEG-based Gel Polymer Electrolyte and Its Application to Electrochromic Devices

    Institute of Scientific and Technical Information of China (English)

    GONG Yong-Feng; FU Xiang-Kai; ZHANG Shu-Peng; JIANG Qing-Long

    2007-01-01

    A star network polymer with a pentaerythritol core linking four PEG-block polymeric arms was synthesized,and its corresponding gel polymer electrolyte based on lithium perchlorate and plasticizers EC/PC with the character being colorless and highly transparent has been also prepared. The polymer host was characterized and confirmed to be of a star network and an amorphous structure by FTIR, 1H NMR and XRD studies. The polymer host hold good mechanical properties for pentaerythritol cross-linking. Maximum ionic conductivity of the prepared electrolyte showed that the thermal stability was up to at least 150 ℃. The gel polymer electrolyte was further evaluated in electrochromic devices fabricated by transparent PET-ITO and electrochromically active viologen derivative films, and its excellent performance promised the usage of the gel polymer electrolyte as ionic conductor material in electrochrornic devices.

  1. All-solid-state proton battery using gel polymer electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Kuldeep, E-mail: mishkuldeep@gmail.com [Department of Applied Science and Humanities, ABES Engineering College, Ghaziabad-201009, India and Department of Physics and Materials Science and Engineering, Jaypee Institute of Information Technology, Noida-201307 (India); Pundir, S. S.; Rai, D. K. [Department of Physics and Materials Science and Engineering, Jaypee Institute of Information Technology, Noida-201307 (India)

    2014-04-24

    A proton conducting gel polymer electrolyte system; PMMA+NH{sub 4}SCN+EC/PC, has been prepared. The highest ionic conductivity obtained from the system is 2.5 × 10−4 S cm{sup −1}. The optimized composition of the gel electrolyte has been used to fabricate a proton battery with Zn/ZnSO{sub 4}⋅7H{sub 2}O anode and MnO{sub 2} cathode. The open circuit voltage of the battery is 1.4 V and the highest energy density is 5.7 W h kg−1 for low current drain.

  2. Utilizing ATRP to Design Self-Regenerating Polymer Gels

    Science.gov (United States)

    Yong, Xin; Averick, Saadyah; Kuksenok, Olga; Matyjaszewski, Krzysztof; Balazs, Anna

    2014-03-01

    Using newly developed computational approaches, we design a gel system capable of re-growth after a substantial section of the material was cut away. Atom transfer radical polymerization (ATRP) is utilized to form gels with preserved ``living'' chain ends and residual unreacted cross-linking groups. When this ``living'' gel is cut, these active species are exposed to a solution containing monomer, crosslinker, initiator and catalyst. A ``repairing'' polymerization occurs from both the new initiators introduced in the outer solution and the reactive chain ends present at the cut site. This new polymerization results in a covalent linkage between the initial living gel and the new gel prepared in the outer solution, and the connection is promoted by the presence of residual cross-linking groups. By measuring the diffusion of the outer solution into the cut gel and characterizing the width and strength of the interface between the initial and new gels, we identify the optimum parameters that yield a strong interface between the gel layers. Our simulations results are in good agreement with our experimental studies. This strategy not only regenerates ``injured'' gels, but also offers a novel means to engineer multi-layered composite gels.

  3. Morphological changes of gel-type functional polymers after intermatrix synthesis of polymer stabilized silver nanoparticles

    OpenAIRE

    Bastos-Arrieta, Julio; Muñoz, Maria; Ruiz, Patricia; Muraviev, Dmitri N.

    2013-01-01

    This paper reports the results of intermatrix synthesis (IMS) of silver metal nanoparticles (Ag-MNPs) in Purolite C100E sulfonic ion exchange polymer of the gel-type structure. It has been shown that the surface morphology of the initial MNP-free polymer is absolutely smooth, but it dramatically changes after the kinetic loading of Ag on the polymer and then IMS of Ag-MNPs. These morphological changes can be explained by the interaction of Ag-NPs with the polymer chains, leading to a sort of ...

  4. Investigation on poly (vinylidene fluoride) based gel polymer electrolytes

    Indian Academy of Sciences (India)

    S Rajendran; P Sivakumar; Ravi Shanker Babu

    2006-12-01

    An investigation is carried out on gel polymer electrolytes consisting of poly (vinylidene fluoride) (PVdF) as a host polymer, lithium perchlorate (LiClO4), lithium triflate (LiCF3SO3) as salts and mixture of ethylene carbonate (EC) and propylene carbonate (PC) as plasticizers. Polymer thin films were prepared by solvent casting technique and the obtained films were subjected to different characterizations, to confirm their structure, complexation and thermal changes. X-ray diffraction revealed that the salts and plasticizers disrupted the crystalline nature of PVdF based polymer electrolytes and converted them into an amorphous phase. TG/DTA studies showed the thermal stability of the polymer electrolytes. The role of interaction between polymer hosts on conductivity is discussed using the results of a.c. impedance studies. Room temperature (28°C) conductivity of 2.786 × 10-3 Scm-1 was observed in PVdF (24)–EC/PC (68)–LiCF3SO3 (2)/LiClO4 (6) polymer system.

  5. Surface structure of polymer Gels and emerging functions

    CERN Document Server

    Kobiki, Y

    1999-01-01

    We report the surface structure of polymer gels on a submicrometer scale during the volume phase transition. Sponge-like domains with a mesoscopic scale were directly observed in water by using at atomic force microscope (AFM). The surface structure characterized by the domains is discussed in terms of the root-mean-square roughness and the auto-correlation function, which were calculated from the AFM images. In order to demonstrate the role of surface structure in determining the macroscopic properties of film-like poly (N-isopropylacrylamide: NIPA) gels. It was found that the temperature dependence, as well as the absolute values of the static contact angle, were strongly dependent on the bulk network inhomogeneities. The relation between the mesoscopic structure and the macroscopic properties is qualitatively discussed in terms of not only the changes in the chemical, but also in the physical, surface properties of the NIPA gels in response to a temperature change.

  6. Structural and cooperative length scales in polymer gels.

    Science.gov (United States)

    Géraud, Baudouin; Jørgensen, Loren; Ybert, Christophe; Delanoë-Ayari, Hélène; Barentin, Catherine

    2017-01-01

    Understanding the relationship between the material structural details, the geometrical confining constraints, the local dynamical events and the global rheological response is at the core of present investigations on complex fluid properties. In the present article, this problem is addressed on a model yield stress fluid made of highly entangled polymer gels of Carbopol which follows at the macroscopic scale the well-known Herschel-Bulkley rheological law. First, performing local rheology measurements up to high shear rates ([Formula: see text] s(-1))and under confinement, we evidence unambiguously the breakdown of bulk rheology associated with cooperative processes under flow. Moreover, we show that these behaviors are fully captured with a unique cooperativity length [Formula: see text] over the whole range of experimental conditions. Second, we introduce an original optical microscopy method to access structural properties of the entangled polymer gel in the direct space. Performing image correlation spectroscopy of fluorophore-loaded gels, the characteristic size D of carbopol gels microstructure is determined as a function of preparation protocol. Combining both dynamical and structural information shows that the measured cooperative length [Formula: see text] corresponds to 2-5 times the underlying structural size D, thus providing a strong grounding to the "Shear Transformation Zones" modeling approach.

  7. Fracturing Fluid (Guar Polymer Gel Degradation Study by using Oxidative and Enzyme Breaker

    Directory of Open Access Journals (Sweden)

    Aung Kyaw

    2012-06-01

    Full Text Available Oxidative and enzyme breakers are used in this research project with the main objective to study on the degradation pattern of fracturing fluid (i.e., guar polymer gel as a function of time, temperature and breaker concentration itself. The fracturing fluid used in hydraulic fracturing or frac pack contain a chemical breakers to reduce the viscosity of the fluid intermingled with the proppant. Chemical breakers reduce viscosity of the guar polymer by cleaving the polymer into small-molecular-weight fragments. The reduction of viscosity will facilitate the flow-back of residual polymer providing rapid recovery of polymer from proppant pack. Ineffective breakers or misapplication of breakers can result in screen-outs or flow-back of viscous fluids both of which can significantly decrease the well productivity. Breaker activity of low to medium temperature range oxidative and enzyme breaker systems was evaluated. ViCon NF an oxidative breaker (Halliburton product and GBW 12- CD an enzyme breaker (BJ Services product were used in this research project with the main objective to study on the degradation pattern of fracturing fluid (guar polymer gel as a function of (time, temperature and breaker concentration itself. This study provides focuses on the way to mix the fracturing fluid, compositions of the fracturing fluid and how to conduct the crosslink and break test. Crosslink test indicate the optimum cross-linker concentration to produce good crosslink gel and the break test gave the characteristic of the gel during degradation process and also the break time. Besides relying on the laboratory experiment, information obtained from research on SPE and US Pattern papers were used to make a comparison study on oxidative and enzyme breakers properties. Degradation pattern observed from the break test showed that reduction in gel viscosity depends on time, temperature and breaker concentration. Observations from experiment also revealed that small

  8. Gel-based composite polymer electrolytes with novel hierarchical mesoporous silica network for lithium batteries

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xiaoliang; Cai Qiang [Department of Materials Science and Engineering, and State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University, Beijing 100084 (China); Fan Lizhen [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Hua Tao; Lin Yuanhua [Department of Materials Science and Engineering, and State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University, Beijing 100084 (China); Nan Cewen [Department of Materials Science and Engineering, and State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University, Beijing 100084 (China)], E-mail: cwnan@tsinghua.edu.cn

    2008-11-15

    In the present work, novel gel-based composite polymer electrolytes for lithium batteries were prepared by introducing a hierarchical mesoporous silica network to the poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP)-based gel electrolytes. As compared with the PVDF-HFP-based gel electrolytes with/without conventional nano-sized silica fillers, the novel electrolytes have shown more homogeneous microstructure, higher ionic conductivity and better mechanical stability, which could be caused by the strong silica network and the effective interactions among the polymer, the liquid electrolytes and the silica. Moreover, the cell with this kind of electrolytes could achieve a discharge capacity as much as 150 mAh g{sup -1} at room temperature (LiCoO{sub 2} as the cathode active material), with high Coulomb efficiency.

  9. Gel-based composite polymer electrolytes with novel hierarchical mesoporous silica network for lithium batteries

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiao-Liang; Cai, Qiang; Hua, Tao; Lin, Yuan-Hua; Nan, Ce-Wen [Department of Materials Science and Engineering, and State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University, Beijing 100084 (China); Fan, Li-Zhen [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

    2008-11-15

    In the present work, novel gel-based composite polymer electrolytes for lithium batteries were prepared by introducing a hierarchical mesoporous silica network to the poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP)-based gel electrolytes. As compared with the PVDF-HFP-based gel electrolytes with/without conventional nano-sized silica fillers, the novel electrolytes have shown more homogeneous microstructure, higher ionic conductivity and better mechanical stability, which could be caused by the strong silica network and the effective interactions among the polymer, the liquid electrolytes and the silica. Moreover, the cell with this kind of electrolytes could achieve a discharge capacity as much as 150 mAh g{sup -1} at room temperature (LiCoO{sub 2} as the cathode active material), with high Coulomb efficiency. (author)

  10. Polymer sol-gel composite inverse opal structures.

    Science.gov (United States)

    Zhang, Xiaoran; Blanchard, G J

    2015-03-25

    We report on the formation of composite inverse opal structures where the matrix used to form the inverse opal contains both silica, formed using sol-gel chemistry, and poly(ethylene glycol), PEG. We find that the morphology of the inverse opal structure depends on both the amount of PEG incorporated into the matrix and its molecular weight. The extent of organization in the inverse opal structure, which is characterized by scanning electron microscopy and optical reflectance data, is mediated by the chemical bonding interactions between the silica and PEG constituents in the hybrid matrix. Both polymer chain terminus Si-O-C bonding and hydrogen bonding between the polymer backbone oxygens and silanol functionalities can contribute, with the polymer mediating the extent to which Si-O-Si bonds can form within the silica regions of the matrix due to hydrogen-bonding interactions.

  11. Motility initiation in active gels

    CERN Document Server

    Recho, Pierre; Truskinovsky, Lev

    2015-01-01

    Motility initiation in crawling cells requires a symmetry breaking mechanism which transforms a symmetric state into a polarized state. Experiments on keratocytes suggest that polarization is triggered by increased contractility of motor proteins. In this paper we argue that contraction can be responsible not only for the symmetry breaking transition but also for the incipient translocation of the segment of an active gel mimicking the crawling cell. Our model suggests that when the contractility increases sufficiently far beyond the motility initiation threshold, the cell can stop and re-symmetrizes. The proposed theory reproduces the motility initiation pattern in fish keratocytes and the behavior of keratocytes prior to cell division.

  12. Uptake and Recovery of Lead by Agarose Gel Polymers

    Directory of Open Access Journals (Sweden)

    Anurag Pandey

    2009-01-01

    Full Text Available Problem statement: The uptake and recovery of lead ions were investigated by using agarose gel polymers. Approach: The experimental results showed that the agarose gel were effective in removing Pb (II from solution. Biosorption equilibrium was approached within 4 h. Pseudo second-order was applicable to all the sorption data over the entire time range. Results: The sorption data conformed well to both the Langmuir and the Freundlich isotherm model. The maximum adsorption capacity (qmax onto agarose gel was 115 mg g-1 for Pb (II. The maximum uptake of metal ions was obtained at pH 2.0. At temperature 35°C, the biosorption of metal ions was found to be highest, with increase or decrease in temperature resulted in a decrease in the metal ions uptake capacity. Conclusion: Elution experiments were carried out to remove Pb (II ions from loaded agarose gel and the bound metal ions could be eluted successfully using 0.1 M EDTA solution. The results suggest that agarose gel can be used as a biosorbent for an efficient removal of Pb(II ions from aqueous solution.

  13. Active nematic gels as active relaxing solids

    OpenAIRE

    Turzi, Stefano S

    2017-01-01

    I put forward a continuum theory for active nematic gels, defined as fluids or suspensions of orientable rodlike objects endowed with active dynamics, that is based on symmetry arguments and compatibility with thermodynamics. The starting point is our recent theory that models (passive) nematic liquid crystals as relaxing nematic elastomers. The interplay between viscoelastic response and active dynamics of the microscopic constituents is naturally taken into account. By contrast with standar...

  14. Self-Pumping Active Gel

    Science.gov (United States)

    Wu, Kun-Ta; Hishamunda, Jean Bernard; Fraden, Seth; Dogic, Zvonimir

    Isotropic active gels are the network which is consist of cross-linked building blocks and the structure of which changes randomly and isotropically with time. Dogic et. al. show that pairs of anti-parallel microtubules form extensile bundles, which merge, extend, and buckle. In an unconfined system, the dynamics of these bundles causes spontaneous turbulent-like flow driven by motion of microscopic molecular motors. We found that confining these active gels in a millimeter sized toroids causes a transition into a new dynamical state characterized by circulation currents persisting for hours until ATP is depleted. We show how toroid dimensions impact the properties of self-organized circular currents, how directions of circulation can be designed by engineering ratchet-shaped boundaries, and how circulations of connected toroids can be either synchronized or antisynchronized. Furthermore, we demonstrate that the flow rate in the circulation is independent of curvature and length of flow path. The flow rate persists for centimeters without decay, disregarding conventional pipe flow resistance. Such findings pave the path to self-pumping pipe transport and performing physical work with biological system.

  15. Mechanical stability of end-linked polymer gel

    Energy Technology Data Exchange (ETDEWEB)

    Roy Majumder, Shashwati [Theoretical Chemistry Section, Radiation Chemistry and Chemical Dynamics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Bandyopadhyay, Tusar [Theoretical Chemistry Section, Radiation Chemistry and Chemical Dynamics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)]. E-mail: btusar@barc.ernet.in; Ghosh, Swapan K. [Theoretical Chemistry Section, Radiation Chemistry and Chemical Dynamics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

    2005-11-01

    The mechanical stability of end-linked polymer network (gel) at large deformation has been studied with the aid of a simplified model. The model consists of square network of end-linked Hookean spring, each representing an ideal polymer chain. To mimic the structure prevailing at the gel point, the square network of springs was self-similarly repeated to generate a deterministic fractal structure having fractal dimensions, d{sub f}=1.56-1.8. For any given d{sub f}, the distribution of pores (measured by lacunarity of the network) in the structure also serves as an important parameter that characterizes the morphology of the network. Our preliminary results show that the present minimalist model qualitatively reproduces the non-monotonous structure-stability relationship, as observed in radiation-induced cross-linked polymer networks. Structures with highest lacunarity for a given fractal network have also been found to exhibit highest mechanical stability against an external deforming force before it is finally crumpled and found to form a wrinkled network.

  16. Fracture energy of polymer gels with controlled network structures

    Science.gov (United States)

    Akagi, Yuki; Sakurai, Hayato; Gong, Jian Ping; Chung, Ung-il; Sakai, Takamasa

    2013-10-01

    We have investigated the fracture behaviors of tetra-arm polyethylene glycol (Tetra-PEG) gels with controlled network structures. Tetra-PEG gels were prepared by AB-type crosslink-coupling of mutually reactive tetra-arm prepolymers with different concentrations and molecular weights. This series of controlled network structures, for the first time, enabled us to quantitatively examine the Lake-Thomas model, which is the most popular model predicting fracture energies of elastomers. The experimental data showed good agreement with the Lake-Thomas model, and indicated a new molecular interpretation for the displacement length (L), the area around a crack tip within which the network strands are fully stretched. L corresponded to the three times of end-to-end distance of network strands, regardless of all parameters examined. We conclude that the Lake-Thomas model can quantitatively predict the fracture energy of polymer network without trapped entanglements, with the enhancement factor being near 3.

  17. Electrolyte transport in neutral polymer gels embedded with charged inclusions

    Science.gov (United States)

    Hill, Reghan

    2005-11-01

    Ion permeable membranes are the basis of a variety of molecular separation technologies, including ion exchange, gel electrophoresis and dialysis. This work presents a theoretical model of electrolyte transport in membranes comprised of a continuous polymer gel embedded with charged spherical inclusions, e.g., biological cells and synthetic colloids. The microstructure mimics immobilized cell cultures, where electric fields have been used to promote nutrient transport. Because several important characteristics can, in principle, be carefully controlled, the theory provides a quantitative framework to help tailor the bulk properties for enhanced molecular transport, microfluidic pumping, and physicochemical sensing applications. This talk focuses on the electroosmotic flow driven by weak electric fields and electrolyte concentration gradients. Also of importance is the influence of charge on the effective ion diffusion coefficients, bulk electrical conductivity, and membrane diffusion potential.

  18. Thermostable gel polymer electrolyte based on succinonitrile and ionic liquid for high-performance solid-state supercapacitors

    Science.gov (United States)

    Pandey, Gaind P.; Liu, Tao; Hancock, Cody; Li, Yonghui; Sun, Xiuzhi Susan; Li, Jun

    2016-10-01

    A flexible, free-standing, thermostable gel polymer electrolyte based on plastic crystalline succinonitrile (SN) and ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate (BMImBF4) entrapped in copolymer poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) is prepared and optimized for application in solvent-free solid-state supercapacitors. The synthesized gel polymer electrolyte exhibits a high ionic conductivity over a wide temperature range (from ∼5 × 10-4 S cm-1 at -30 °C up to ∼1.5 × 10-2 S cm-1 at 80 °C) with good electrochemical stability window (-2.9 to 2.5 V). Thermal studies confirm that the SN containing gel polymer electrolyte remains stable in the same gel phase over a wide temperature range from -30 to 90 °C. The electric double layer capacitors (EDLCs) have been fabricated using activated carbon as active materials and new gel polymer electrolytes. Electrochemical performance of the EDLCs is assessed through cyclic voltammetry, galvanostatic charge-discharge cycling and impedance spectroscopy. The EDLC cells with the proper SN-containing gel polymer electrolyte has been found to give high specific capacitance 176 F g-1 at 0.18 A g-1 and 138 F g-1 at 8 A g-1. These solid-state EDLC cells show good cycling stability and the capability to retain ∼80% of the initial capacitance after 10,000 cycles.

  19. Gelation Behavior of Poly (Vinylidene Fluoride )-based Gel Polymer Electrolyte

    Institute of Scientific and Technical Information of China (English)

    WANG Biao-bing; GU Li-xia

    2006-01-01

    Poly ( vinylidene fluoride ) ( PVdF )-based gel polymer electrolytes with various compositions were prepared by solution casting technique. The kinetics of gelation was analyzed via the correlation between the apparent gelation rate and concentration of PVdF at a given temperature.Combination the results of the kinetics of gelation and the DSC study, it revealed that the phase separation was the major behavior and the fibrils were the major junction joints of the three-dimensional network even in the ease the concentration of PVdF was higher than 25 wt%. The porous surface observed by ESEM also reflected that the phase separation took place during the gelation.

  20. Autonomous Oscillation of Nonthermoresponsive Polymers and Gels Induced by the Belousov–Zhabotinsky Reaction

    Directory of Open Access Journals (Sweden)

    Yusuke Hara

    2013-09-01

    Full Text Available This review introduces the self-oscillating behavior of two types of nonthermoresponsive polymer systems with Ru catalyst moieties for the Belousov-Zhabotinsky (BZ reaction: one with a poly-vinylpyrrolidone (PVP main chain, and the other with a poly(2-propenamide (polyacrylamide (PAM main chain. The amplitude of the VP-based self-oscillating polymer chain and the activation energy for self-oscillation are hardly affected by the initial concentrations of the BZ substrates. The influences of the initial concentrations of the BZ substrates and the temperature on the period of the swelling-deswelling self-oscillation are examined in detail. Logarithmic plots of the period against the initial concentration of one BZ substrate, when the concentrations of the other two BZ substrates are fixed, show good linear relationships. The period of the swelling-deswelling self-oscillation decreases with increasing temperature, in accordance with the Arrhenius equation. The maximum frequency (0.5 Hz of the poly(VP-co-Ru(bpy3 gel is 20 times that of the poly(NIPAAm-co-Ru(bpy3 gel. It is also demonstrated that the amplitude of the volume self-oscillation for the gel has a tradeoff with the self-oscillation period. In addition, this review reports the self-oscillating behavior of an AM-based self-oscillating polymer chain as compared to that of the VP-based polymer chain.

  1. Energy dependence of polymer gels in the orthovoltage energy range

    Directory of Open Access Journals (Sweden)

    Yvonne Roed

    2014-03-01

    Full Text Available Purpose: Ortho-voltage energies are often used for treatment of patients’ superficial lesions, and also for small- animal irradiations. Polymer-Gel dosimeters such as MAGAT (Methacrylic acid Gel and THPC are finding increasing use for 3-dimensional verification of radiation doses in a given treatment geometry. For mega-voltage beams, energy dependence of MAGAT has been quoted as nearly energy-independent. In the kilo-voltage range, there is hardly any literature to shade light on its energy dependence.Methods: MAGAT was used to measure depth-dose for 250 kVp beam. Comparison with ion-chamber data showed a discrepancy increasing significantly with depth. An over-response as much as 25% was observed at a depth of 6 cm.Results and Conclusion: Investigation concluded that 6 cm water in the beam resulted in a half-value-layer (HVL change from 1.05 to 1.32 mm Cu. This amounts to an effective-energy change from 81.3 to 89.5 keV. Response measurements of MAGAT at these two energies explained the observed discrepancy in depth-dose measurements. Dose-calibration curves of MAGAT for (i 250 kVp beam, and (ii 250 kVp beam through 6 cm of water column are presented showing significant energy dependence.-------------------Cite this article as: Roed Y, Tailor R, Pinksy L, Ibbott G. Energy dependence of polymer gels in the orthovoltage energy range. Int J Cancer Ther Oncol 2014; 2(2:020232. DOI: 10.14319/ijcto.0202.32 

  2. PREPARATION OF STAR NETWORK PEG-BASED GEL POLYMER ELECTROLYTES FOR ELECTROCHROMIC DEVICES

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    An amorphous,colorless,and highly transparent star network polymer with a pentaerythritol core linking four PEG-block polymeric arms was synthesized from the poly(ethylene glycol)(PEG),pentaerythritol,and dichloromethane by Williamson reaction.FTIR and 1H-NMR measurement demonstrated that the polymer repeating units were C[CH2-OCH2O-(CH2CH2O)m-CH2O-(CH2CH2O)n-CH2O]4.The polymer host held well mechanical properties for pentaerythritol cross-linking.The gel polymer electrolytes based on Lithium perchlorate(LiClO4)and ethylene carbonate/propylene carbonate(EC/PC)were prepared and characterized by AC impedance spectroscopy and thermogravimetry(TG),the results showed thermal stability up to at least 150℃ and ionic conductivity reaching 8.83×fabricated by transparent PET-ITO and electrochromic active viologen derivative films,and its excellent performance promised the usage of the gel polymer electrolytes as ionic conductor material in ECD.

  3. Designing Solvent Exchange-Induced In Situ Forming Gel from Aqueous Insoluble Polymers as Matrix Base for Periodontitis Treatment.

    Science.gov (United States)

    Srichan, Tharatree; Phaechamud, Thawatchai

    2017-01-01

    An in situ forming gel is a dosage form which is promised for site-specific therapy such as periodontal pocket of periodontitis treatment. Ethylcellulose, bleached shellac, and Eudragit RS were applied in this study as a polymeric matrix for in situ forming gel employing N-methyl pyrrolidone (NMP) as solvent. Solutions comprising ethylcellulose, bleached shellac, and Eudragit RS in NMP were evaluated for viscosity, rheology, and rate of water penetration. Ease of administration by injection was determined as the force required to expel polymeric solutions through a needle using texture analyzer. In vitro gel formation and in vitro gel degradation were conducted after injection into phosphate buffer solution pH 6.8. Ethylcellulose, bleached shellac, and Eudragit RS could form the in situ gel, in vitro. Gel viscosity and pH value depended on percentage amount of the polymer, whereas the water diffusion at early period likely relied on types of polymer. Furthermore, the solutions containing higher polymer concentration exhibited the lower degree of degradation. All the preparations were acceptable as injectable dosage forms because the applied force was lower than 50 N. All of them inhibited Staphylococcus aureus, Escherichia coli, Candida albicans, Streptococcus mutans, and Porphyrommonas gingivalis growth owing to antimicrobial activity of NMP which exhibited a potential use for periodontitis treatment. Moreover, the developed systems presented as the solvent exchange induced in situ forming gel and showed capability to be incorporated with the suitable antimicrobial active compounds for periodontitis treatment which should be further studied.

  4. Langevin dynamcis simulations of driven polymer translocation into a cross-linked gel.

    Science.gov (United States)

    Sean, David; Slater, Gary W

    2017-03-01

    We investigate the dynamics of driving a polyelectrolyte such as DNA through a nanopore and into a cross-linked gel. Placing the gel on the trans-side of the nanopore can increase the translocation time while not negatively affecting the capture rates. Thus, this setup combines the mechanics of gel electrophoresis with nanopore translocation. However, contrary to typical gel electrophoresis scenarios, the effect of the field is localized in the immediate vicinity of the nanopore and becomes negligible inside the gel matrix. Thus, we investigate the process by which a semiflexible polymer can be pushed into a gel matrix via a localized field and we describe how the dynamics of gel penetration depends upon the field intensity, polymer stiffness, and gel pore size. Our simulation results show that a semiflexible polymer enters the gel region with two distinct mechanisms depending upon the ratio between the bending length scale and the gel pore size. In both regimes, the gel fibers cause a net increase in the mean translocation time. Interestingly, the translocation rate is found to be constant (a potentially useful feature for many applications) during the predominant part of the translocation process when the polymer is stiff over a length scale comparable to the gel pore size.

  5. Tubular array, dielectric, conductivity and electrochemical properties of biodegradable gel polymer electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Sudhakar, Y.N. [Department of Chemistry, Manipal Institute of Technology, Manipal, Karnataka (India); Selvakumar, M., E-mail: chemselva78@gmail.com [Department of Chemistry, Manipal Institute of Technology, Manipal, Karnataka (India); Bhat, D. Krishna [Department of Chemistry, National Institute of Technology Karnataka, Surathkal, Mangalore (India)

    2014-02-15

    Highlights: • A new finding of tubular array of 10–20 μm in length and 1–2 μm in thickness of gel polymer electrolyte (GPE) having 2.2 × 10{sup −3} S cm{sup −1} conductivity is reported. • Thermal and electrochemical characterizations of GPEs show good interaction among the polymer, plasticizer and salt. • GPE based supercapacitor demonstrates high capacitance of 186 F g{sup −1}. • Low temperature studies did not influence much on capacitance values obtained from AC impedance studies. • Charge–discharge exhibits high capacity with excellent cyclic stability and energy density. -- Abstract: A supercapacitor based on a biodegradable gel polymer electrolyte (GPE) has been fabricated using guar gum (GG) as the polymer matrix, LiClO{sub 4} as the doping salt and glycerol as the plasticizer. The scanning electron microscopy (SEM) images of the gel polymer showed an unusual tubular array type surface morphology. FTIR, DSC and TGA results of the GPE indicated good interaction between the components used. Highest ionic conductivity and lowest activation energy values were 2.2 × 10{sup −3} S cm{sup −1} and 0.18 eV, respectively. Dielectric studies revealed ionic behavior and good capacitance with varying frequency of the GPE system. The fabricated supercapacitor showed a maximum specific capacitance value of 186 F g{sup −1} using cyclic voltammetry. Variation of temperature from 273 K to 293 K did not significantly influence the capacitance values obtained from AC impedance studies. Galvanostatic charge–discharge study of supercapacitor indicated that the device has good stability, high energy density and power density.

  6. The application of polymer gel dosimeters to dosimetry for targeted radionuclide therapy

    Energy Technology Data Exchange (ETDEWEB)

    Gear, J I [Joint Department of Physics, Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Sutton, Surrey (United Kingdom); Flux, G D [Joint Department of Physics, Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Sutton, Surrey (United Kingdom); Charles-Edwards, E [Clinical Magnetic Research Group, Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Sutton, Surrey (United Kingdom); Partridge, M [Joint Department of Physics, Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Sutton, Surrey (United Kingdom); Cook, G [Department of Nuclear Medicine, Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Sutton, Surrey (United Kingdom); Ott, R J [Joint Department of Physics, Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Sutton, Surrey (United Kingdom)

    2006-07-21

    There is a lack of standardized methodology to perform dose calculations for targeted radionuclide therapy and at present no method exists to objectively evaluate the various approaches employed. The aim of the work described here was to investigate the practicality and accuracy of calibrating polymer gel dosimeters such that dose measurements resulting from complex activity distributions can be verified. Twelve vials of the polymer gel dosimeter, 'MAGIC', were uniformly mixed with varying concentrations of P-32 such that absorbed doses ranged from 0 to 30 Gy after a period of 360 h before being imaged on a magnetic resonance scanner. In addition, nine vials were prepared and irradiated using an external 6 MV x-ray beam. Magnetic resonance transverse relaxation time, T{sub 2}, maps were obtained using a multi-echo spin echo sequence and converted to R{sub 2} maps (where T{sub 2} = 1/R{sub 2}). Absorbed doses for P-32 irradiated gel were calculated according to the medical internal radiation dose schema using EGSnrc Monte Carlo simulations. Here the energy deposited in cylinders representing the irradiated vials was scored. A relationship between dose and R{sub 2} was determined. Effects from oxygen contamination were present in the internally irradiated vials. An increase in O{sub 2} sensitivity over those gels irradiated externally was thought to be a result of the longer irradiation period. However, below the region of contamination dose response appeared homogenous. Due do a drop-off of dose at the periphery of the internally irradiated vials, magnetic resonance ringing artefacts were observed. The ringing did not greatly affect the accuracy of calibration, which was comparable for both methods. The largest errors in calculated dose originated from the initial activity measurements, and were approximately 10%. Measured R{sub 2} values ranged from 5-35 s{sup -1} with an average standard deviation of 1%. A clear relationship between R{sub 2} and dose was

  7. Composite gel polymer electrolyte for lithium ion batteries

    Science.gov (United States)

    Naderi, Roya

    Composite gel polymer electrolyte (CGPE) films, consisting of poly (vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) as the membrane, DMF and PC as solvent and plasticizing agent, mixture of charge modified TiO2 and SiO 2 nano particles as ionic conductors, and LiClO4+LiPF 6 as lithium salts were fabricated. Following the work done by Li et al., CGPE was coated on an O2-plasma treated trilayer polypropylene-polyethylene-polypropylene membrane separator using solution casting technique in order to improve the adhesive properties of gel polymer electrolyte to the separator membrane and its respective ionic conductivity due to decreasing the bulk resistance. In acidic CGPE with, the mixture of acid treated TiO2 and neutral SiO2 nano particles played the role of the charge modified nano fillers with enhanced hydroxyl groups. Likely, the mixture of neutral TiO 2 nano particles with basic SiO2 prepared through the hydrolization of tetraethyl orthosilicate (TEOS) provided a more basic environment due to the residues of NH4OH (Ammonium hydroxide) catalyst. The O2 plasma treated separator was coated with the solution of PVDF-HFP: modified nano fillers: Organic solvents with the mixture ratio of 0.1:0.01:1. After the evaporation of the organic solvents, the dried coated separator was soaked in PC-LiClO4+LiPF6 in EC: DMC:DEC (4:2:4 in volume) solution (300% wt. of PVDF-HFP) to form the final CGPE. Lim et al. has reported the enhanced ionic conductivity of 9.78*10-5 Scm-1 in an acidic composite polystyrene-Al2O3 solid electrolyte system with compared to that of basic and neutral in which the ionic conductivity undergoes an ion hopping process in solid interface rather than a segmental movement of ions through the plasticized polymer chain . Half-cells with graphite anode and Li metal as reference electrode were then assembled and the electrochemical measurements and morphology examinations were successfully carried out. Half cells demonstrated a considerable change in their

  8. Ionic conductivity of polymer gels deriving from alkali metal ionic liquids and negatively charged polyelectrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Ogihara, Wataru; Yoshizawa, Masahiro; Ohno Hiroyuki [Tokyo University of Agriculture and Technology (Japan). Dept. of Biotechnology; Sun, Jiazeng; Forsyth, M. [Monash University, Clayton (Australia). School of Materials Engineering; MacFarlane, D.R. [Monash University, Clayton (Australia). School of Chemistry

    2004-04-30

    We have prepared polymer gel electrolytes with alkali metal ionic liquids (AMILs) that inherently contain alkali metal ions. The AMIL consisted of sulfate anion, imidazolium cation, and alkali metal cation. AMILs were mixed directly with poly(3-sulfopropyl acrylate) lithium salt or poly(2-acrylamido-2-methylpropanesulfonic acid) lithium salt to form polymer gels. The ionic conductivity of these gels decreased with increasing polymer fraction, as in general ionic liquid/polymer mixed systems. At low polymer concentrations, these gels displayed excellent ionic conductivity of 10{sup -4} to 10{sup -3} S cm{sup -1} at room temperature. Gelation was found to cause little change in the {sup 7}Li diffusion coefficient of the ionic liquid, as measured by pulse-field-gradient NMR. These data strongly suggest that the lithium cation migrates in successive pathways provided by the ionic liquids. (author)

  9. Technical considerations for implementation of x-ray CT polymer gel dosimetry

    Science.gov (United States)

    Hilts, M.; Jirasek, A.; Duzenli, C.

    2005-04-01

    Gel dosimetry is the most promising 3D dosimetry technique in current radiation therapy practice. X-ray CT has been shown to be a feasible method of reading out polymer gel dosimeters and, with the high accessibility of CT scanners to cancer hospitals, presents an exciting possibility for clinical implementation of gel dosimetry. In this study we report on technical considerations for implementation of x-ray CT polymer gel dosimetry. Specifically phantom design, CT imaging methods, imaging time requirements and gel dose response are investigated. Where possible, recommendations are made for optimizing parameters to enhance system performance. The dose resolution achievable with an optimized system is calculated given voxel size and imaging time constraints. Results are compared with MRI and optical CT polymer gel dosimetry results available in the literature.

  10. Study of the relative dose-response of BANG-3® polymer gel dosimeters in epithermal neutron irradiation

    Science.gov (United States)

    Uusi-Simola, J.; Savolainen, S.; Kangasmäki, A.; Heikkinen, S.; Perkiö, J.; Abo Ramadan, U.; Seppälä, T.; Karila, J.; Serén, T.; Kotiluoto, P.; Sorvari, P.; Auterinen, I.

    2003-09-01

    Polymer gels have been reported as a new, potential tool for dosimetry in mixed neutron-gamma radiation fields. In this work, BANG-3 (MGS Research Inc.) gel vials from three production batches were irradiated with 6 MV photons of a Varian Clinac 2100 C linear accelerator and with the epithermal neutron beam of the Finnish boron neutron capture therapy (BNCT) facility at the FiR 1 nuclear reactor. The gel is tissue equivalent in main elemental composition and density and its T2 relaxation time is dependent on the absorbed dose. The T2 relaxation time map of the irradiated gel vials was measured with a 1.5 T magnetic resonance (MR) scanner using spin echo sequence. The absorbed doses of neutron irradiation were calculated using DORT computer code, and the accuracy of the calculational model was verified by measuring gamma ray dose rate with thermoluminescent dosimeters and 55Mn(n,gamma) activation reaction rate with activation detectors. The response of the BANG-3 gel dosimeter for total absorbed dose in the neutron irradiation was linear, and the magnitude of the response relative to the response in the photon irradiation was observed to vary between different gel batches. The results support the potential of polymer gels in BNCT dosimetry, especially for the verification of two- or three-dimensional dose distributions.

  11. Ionic Liquid-Doped Gel Polymer Electrolyte for Flexible Lithium-Ion Polymer Batteries

    Science.gov (United States)

    Zhang, Ruisi; Chen, Yuanfen; Montazami, Reza

    2015-01-01

    Application of gel polymer electrolytes (GPE) in lithium-ion polymer batteries can address many shortcomings associated with liquid electrolyte lithium-ion batteries. Due to their physical structure, GPEs exhibit lower ion conductivity compared to their liquid counterparts. In this work, we have investigated and report improved ion conductivity in GPEs doped with ionic liquid. Samples containing ionic liquid at a variety of volume percentages (vol %) were characterized for their electrochemical and ionic properties. It is concluded that excess ionic liquid can damage internal structure of the batteries and result in unwanted electrochemical reactions; however, samples containing 40–50 vol % ionic liquid exhibit superior ionic properties and lower internal resistance compared to those containing less or more ionic liquids.

  12. Evaluation of interactive effects on the ionic conduction properties of polymer gel electrolytes.

    Science.gov (United States)

    Saito, Yuria; Okano, Miki; Kubota, Keigo; Sakai, Tetsuo; Fujioka, Junji; Kawakami, Tomohiro

    2012-08-23

    Ionic mobility of electrolyte materials is essentially determined by the nanoscale interactions, the ion-ion interactions and ion-solvent interactions. We quantitatively evaluated the interactive situation of the lithium polymer gel electrolytes through the measurements of ionic conductivity and diffusion coefficients of the mobile species of the lithium polymer electrolytes. The interactive force between the cation and anion in the gel depended on the mixing ratio of the binary solvent, ethylene carbonate plus dimethyl carbonate (EC/DMC). The gel with the solvent (3:7 EC:DMC) showed minimal cation-anion interaction, which is the cause of the highest ionic mobility compared with those of the other gels with different solvents. This suggests that the cation-anion interaction does not simply depend on the dielectric constant of the solvent but is associated with the solvation condition of the lithium. In the case of the gel with the 3:7 EC/DMC solvent, most of the EC species strongly coordinate to a lithium ion, forming the stable solvated lithium, Li(EC)(3)(+), and there are no residual EC species for exchange with them. As a result, the solvating EC species would be a barrier that restricts the anion attack to the lithium leading to the smallest cation-anion interaction. On the other hand, interaction between the cation and polar sites, hydroxyl and oxygen groups of ether of the polyvinyl butyral (PVB) and polyethylene oxide (PEO) polymer, respectively, in the gels was another dominant factor responsible for cation mobility. It increased with increasing polar site concentration per lithium. In case of the PVB gels, cation-anion interaction increased with an increasing polymer fraction of the gel contrary to the independent feature of PEO gels with the change of the polymer fraction. This indicates that the cation-anion interaction is associated with the polymer structure of the gel characterized by the kind and configuration of polar groups, molecular weight, and

  13. Polymer gels with associating side chains and their interaction with surfactants

    Science.gov (United States)

    Gordievskaya, Yulia D.; Rumyantsev, Artem M.; Kramarenko, Elena Yu.

    2016-05-01

    Conformational behaviour of hydrophobically modified (HM) polymer gels in solutions of nonionic surfactants is studied theoretically. A HM gel contains hydrophobic side chains (stickers) grafted to its subchains. Hydrophobic stickers are capable to aggregate into joint micelles with surfactant molecules. Micelles containing more than one sticker serve as additional physical cross-links of the network, and their formation causes gel shrinking. In the proposed theoretical model, the interior of the gel/surfactant complex is treated as an array of densely packed spherical polymer brushes consisting of gel subchains tethered to the surface of the spherical sticker/surfactant micelles. Effect of stickers length and grafting density, surfactant concentration and hydrophobicity on gel swelling as well as on hydrophobic association inside it is analyzed. It is shown that increasing surfactant concentration can result in a gel collapse, which is caused by surfactant-induced hydrophobic aggregation of stickers, and a successive gel reswelling. The latter should be attributed to a growing fraction of surfactants in joint aggregates and, hence, increasing number of micelles containing only one sticker and not participating in gel physical cross-linking. In polyelectrolyte (PE) gels hydrophobic aggregation is opposed by osmotic pressure of mobile counterions, so that at some critical ionization degree hydrophobic association is completely suppressed. Hydrophobic modification of polymers is shown to open new ways for controlling gel responsiveness. In particular, it is discussed that incorporation of photosensitive groups into gel subchains and/or surfactant tail could give a possibility to vary the gel volume by light. Since hydrophobic aggregation regularities in gels and solutions are common, we hope our findings will be useful for design of polymer based self-healing materials as well.

  14. Effect of Oxygen and Bacteria on the Property of Polymer Gel

    Institute of Scientific and Technical Information of China (English)

    Weidong Jiang; Xiangguo Lu; Xinxia Xu

    2007-01-01

    The viscosity property of Cr3+, Al3+, and compound ion cross-linked polymer gel solution in the anaerobic and aerobic environment was investigated aiming at meeting the practical demand of the oil field. The viscosity reserving effect after adding the biocide and the gelation in the anaerobic and aerobic environments was also studied in the paper. The results indicate that the viscosity of the cross-linked polymer gel solution caused by the water produced in aerobic environment is higher than that in anaerobic environment, and that the viscosity value of the cross-linked polymer gel solutions after adding biocides has improved to some extent and polymer gel has gelated well in anaerobic environment.

  15. Crosslinked polymer gel electrolytes based on polyethylene glycol methacrylate and ionic liquid for lithium battery applications

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Chen [ORNL; Sun, Xiao-Guang [ORNL; Dai, Sheng [ORNL

    2013-01-01

    Gel polymer electrolytes were synthesized by copolymerization polyethylene glycol methyl ether methacrylate with polyethylene glycol dimethacrylate in the presence of a room temperature ionic liquid, methylpropylpyrrolidinium bis(trifluoromethanesulfonyl)imide (MPPY TFSI). The physical properties of gel polymer electrolytes were characterized by thermal analysis, impedance spectroscopy, and electrochemical tests. The ionic conductivities of the gel polymer electrolytes increased linearly with the amount of MPPY TFSI and were mainly attributed to the increased ion mobility as evidenced by the decreased glass transition temperatures. Li||LiFePO4 cells were assembled using the gel polymer electrolytes containing 80 wt% MPPY TFSI via an in situ polymerization method. A reversible cell capacity of 90 mAh g 1 was maintained under the current density of C/10 at room temperature, which was increased to 130 mAh g 1 by using a thinner membrane and cycling at 50 C.

  16. Multiple-phase behavior and memory effect of polymer gel

    CERN Document Server

    Annaka, M; Nakahira, T; Sugiyama, M; Hara, K; Matsuura, T

    2002-01-01

    A poly(4-acrylamidosalicylic acid) gel (PASA gel) exhibits multiple phases as characterized by distinct degrees of swelling; the gel can take one of four different swelling values, but none of the intermediate values. The gel has remarkable memory: the phase behavior of the gel depends on whether the gel has experienced the most swollen phase or the most collapsed phase in the immediate past. The information is stored and reversibly erased in the form of a macroscopic phase transition behavior. The structure factors corresponding to these four phases were obtained by SANS, which indicated the presence of characteristic structures depending on pH and temperature, particularly in the shrunken state. (orig.)

  17. In situ synthesis of polymer-clay nanocomposites from silicate gels.

    Energy Technology Data Exchange (ETDEWEB)

    Carrado, K. A.; Xu, L.; Chemistry

    1998-01-01

    Polymer-containing silicate gels were hydrothermally crystallized to form layered magnesium silicate hectorite clays containing polymers that are incorporated in situ. Gels consist of silica sol, magnesium hydroxide sol, lithium fluoride, and the polymer of choice. Dilute solutions of gel in water are refluxed for various lengths of time and then isolated via centrifugation, washed, and air-dried. Polymer loadings up to 86% were attained by adding more polymer to the solutions after 2-day reaction times, reacting for another 24 h, and continuing this process prior to isolation. Polyaniline (PANI)- and polyacrylonitrile (PACN)-clay samples contain up to 57% and 76% polymer, respectively, after just one sequential addition at high polymer loading. Series of PANI-, PACN-, poly(vinylpyrrolidone) (PVP)-, and hydroxypropylmethylcellulose (HPMC)-clays also were prepared by several sequential additions of lower polymer loading to the silicate gel during crystallization. Final polymer loadings were determined by thermal analysis. Basal spacings between clay interlayers were measured by X-ray powder diffraction for all samples. Increases in polymer loadings and basal spacings were observed for all the neutral polymers studied, until or unless delamination occurred. Delamination was evident for PACN- and PANI-clay nanocomposites. The highest loadings were observed for the PACN-clays, up to 86%. For the cationic polymer polydimethyldiallylammonium chloride, however, the loading could not be increased beyond about 20%. This is due to electrostatic interactions that balance the negatively charged sites on the silicate lattice with those on the cationic polymer chain. Beyond charge compensation, there is no driving force for further incorporation. Charge compensation in the case of the neutral polymers is attained by interlayer lithium(I) cations.

  18. Novel Stable Gel Polymer Electrolyte: Toward a High Safety and Long Life Li-Air Battery.

    Science.gov (United States)

    Yi, Jin; Liu, Xizheng; Guo, Shaohua; Zhu, Kai; Xue, Hailong; Zhou, Haoshen

    2015-10-28

    Nonaqueous Li-air battery, as a promising electrochemical energy storage device, has attracted substantial interest, while the safety issues derived from the intrinsic instability of organic liquid electrolytes may become a possible bottleneck for the future application of Li-air battery. Herein, through elaborate design, a novel stable composite gel polymer electrolyte is first proposed and explored for Li-air battery. By use of the composite gel polymer electrolyte, the Li-air polymer batteries composed of a lithium foil anode and Super P cathode are assembled and operated in ambient air and their cycling performance is evaluated. The batteries exhibit enhanced cycling stability and safety, where 100 cycles are achieved in ambient air at room temperature. The feasibility study demonstrates that the gel polymer electrolyte-based polymer Li-air battery is highly advantageous and could be used as a useful alternative strategy for the development of Li-air battery upon further application.

  19. A study on PVDF-HFP gel polymer electrolyte for lithium-ion batteries

    Science.gov (United States)

    Liu, W.; Zhang, X. K.; Wu, F.; Xiang, Y.

    2017-06-01

    In this paper, poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) gel polymer electrolyte was fabricated via solvent casting method in order to improve the performance of the lithium-ion batteries. By comparing the physical and electrochemical properties of PVDF-HFP gel polymer electrolyte with three different proportions, the optimization of the PVDF-HFP gel polymer electrolyte was obtained: 10wt% PVDF-HFP - 80wt% tetrahydrofuran (THF) / acetone - 10wt% 1mol L-1 lithium perchlorate (LiClO4) in elthylene carbonate (EC) and diethyl carbonate (DEC). The optimized PVDF-HFP gel polymer electrolyte displayed a high conductivity of 1.06×10-3 S cm-1 at room temperature, a high lithium transference number of 0.36 and a good thermal stability within 100°C. Moreover, the discharge specific capacity was 135.1 mAh g-1, and the charge / discharge efficiency was 99.1% at 0.1C rate. Therefore, the fabricated PVDF-HFP gel polymer electrolyte was an effective gel polymer electrolyte to be applied on lithium-ion batteries.

  20. MAGIC polymer gel for dosimetric verification in boron neutron capture therapy.

    Science.gov (United States)

    Uusi-Simola, Jouni; Heikkinen, Sami; Kotiluoto, Petri; Serén, Tom; Seppälä, Tiina; Auterinen, Iiro; Savolainen, Sauli

    2007-04-30

    Radiation sensitive polymer gels are among the most promising three-dimensional dose verification tools developed to date. Polymer gel dosimeter known by the acronym MAGIC has been tested for evaluation of its use in boron neutron capture (BNCT) dosimetry. We irradiated a large (diameter 10 cm, length 20 cm) cylindrical gel phantom in the epithermal neutron beam of the Finnish BNCT facility at the FiR 1 nuclear reactor. Neutron irradiation was simulated with a Monte Carlo radiation transport code MCNP. Gel samples from the same production batch were also irradiated with 6 MV photons from a medical linear accelerator to compare dose response in the two different types of beams. Irradiated gel phantoms were imaged using MRI to determine their relaxation rate R2 maps. The measured and normalized dose distribution in the epithermal neutron beam was compared to the dose distribution calculated by computer simulation. The results support the feasibility MAGIC gel in BNCT dosimetry.

  1. Gel formation in systems composed of drug containing catanionic vesicles and oppositely charged hydrophobically modified polymer.

    Science.gov (United States)

    Dew, Noel; Edwards, Katarina; Edsman, Katarina

    2009-05-01

    The aim of this study was to explore if mixtures of drug containing catanionic vesicles and polymers give rise to gel formation, and if so, if drug release from these gels could be prolonged. Catanionic vesicles formed from the drug substances alprenolol or tetracaine, and the oppositely charged surfactant sodium dodecyl sulphate were mixed with polymers. Three polymers with different properties were employed: one bearing hydrophobic modifications, one positively charged and one positively charged polymer bearing hydrophobic modifications. The structure of the vesicles before and after addition of polymer was investigated by using cryo-TEM. Gel formation was confirmed by using rheological measurements. Drug release was studied using a modified USP paddle method. Gels were observed to form only in the case when catanionic vesicles, most likely with a net negative charge, were mixed with positively charged polymer bearing lipophilic modifications. The release of drug substance from these systems, where the vesicles are not trapped within the gel but constitute a founding part of it, could be significantly prolonged. The drug release rate was found to depend on vesicle concentration to a higher extent than on polymer concentration.

  2. Filmogen organic-inorganic hybrids obtained by sol-gel in the presence of cationic polymer

    NARCIS (Netherlands)

    Donescu, Dan; Serban, Sever; Uricanu, Violeta; Duits, Michel; Perichaud, Alain; Olteanu, Mihaela; Spiroiu, Manuela; Vasilescu, Marilena

    2007-01-01

    Self-standing and coated-on-glass films were prepared from polymer-inorganic ormosils, using the cationic polymer poly(methacrylamide propyl quaternarydimethyldodecyl bromide). The inorganic compound was grown in sol-gel reactions based on methyltriethoxysilane (MeTES), with or without addition of t

  3. Macroporous Titania Monolith Prepared via Sol-gel Process with Polymer Foam as the Template

    Institute of Scientific and Technical Information of China (English)

    REN, Jian; DU, Zhong-Jie; ZHANG, Chen; LI, Hang-Quan

    2006-01-01

    Macroporous titania monoliths were prepared via sol-gel method using polymer foam as templates. The polymer foam polymerized via concentrated emulsion polymerization was immerged in a solution of titanium(Ⅳ) isopropoxide in 2-propanol, which underwent a sol-gel process. The organic components were subsequently removed by calcination. The effects of various parameters, including the nature of the monomer, the volume fraction of dispersed phase of the concentrated emulsion, and concentration of the sol-gel solution were investigated. The SEM micrographs of the macroporous titania monoliths thus obtained showed that the porous structure of the final material was effectively controllable.

  4. Light-scattering-induced artifacts in a complex polymer gel dosimetry phantom.

    Science.gov (United States)

    Bosi, Stephen G; Naseri, Pourandokht; Baldock, Clive

    2009-05-01

    Certain polymer gels become turbid on exposure to ionizing radiation, a property exploited in medical dosimetry to produce three-dimensional dose maps for radiotherapy. These maps can be read using optical computed tomography (CT). A test phantom of complex shape ("layered tube") was developed to investigate the optical properties of polymer gel dosimeters when read using optical CT. Extinction coefficient profiles from tomographically reconstructed slices of the phantom exhibited several artifacts. A simple model invoking scattered light in the gel was able to account for all artifacts, which in a real dosimeter may have been mistaken for other phenomena, resulting in incorrect readings of dose.

  5. Associative polymers and physical gels derived from natural biopolymers; Polymeres associes et gels physiques derives de biopolymeres naturels

    Energy Technology Data Exchange (ETDEWEB)

    Muller, G.; Huguet, J.; Merle, L.; Grisel, M.; Picton, L.; Bataille, I.; Charpentier, D.; Glinel, K. [CNRS, Polymeres, Biopolymeres et Membranes, Universite de Rouen, 76 - Mont-Saint-Aignan (France)

    1997-04-01

    Polymers are largely used in oil-field operations where the control of rheology of aqueous phases ids of primary importance. Polymers systems showing high viscosity present many advantages as candidates for drilling muds. Associating polymers, i.e. polymers the hydrophilic main chains of which have been properly modified by introducing hydrophobic groups and weak physical ges are good examples of such systems. The different systems chosen to be studied are derived from natural biopolymers. They are: Alkyl derivatives issued from neutral (HEC) and ionic (CMC) cellulosic ether derivatives; alkyl and fluoro alkyl derivatives from neutral (Pull) and ionic (CMP) bacterial polysaccharide pullulane; weak physical gels resulting from complex formation between borate ions and the neutral fungal polysaccharide schizophyllan. The different results are given in tables and figures. (N.C.)

  6. Polymer composite principles applied to hair styling gels.

    Science.gov (United States)

    Wade Rafferty, Denise; Zellia, Joseph; Hasman, Daniel; Mullay, John

    2008-01-01

    A novel approach is taken to understand the mechanical performance of fixative-treated hair tresses. Polymer composite principles are applied to explain the performance. Examples are given for polyacrylate-2 crosspolymer that show that the choice of neutralizer affects the film properties of anionic acrylic polymers by plasticization or by hardening through ionic (physical) crosslinking. The effect of these changes in the polymer film on the composite properties was determined by mechanical stiffness and high-humidity curl retention testing. It is shown that both adhesion to the hair and polymer cohesion are important in determining fixative polymer performance. The implications of the results for the formulation of fixative systems are discussed.

  7. Nanostructure investigation of polymer solutions, polymer gels, and polymer thin films

    Science.gov (United States)

    Lee, Wonjoo

    This thesis discusses two systems. One is structured hydrogels which are hydrogel systems based on crosslinked poly((2-dimethylamino)ethyl methacrylate) (PDMAEMA) containing micelles which form nanoscale pores within the PDMAEMA hydrogel. The other is nanoporous block copolymer thin films where solvent selectivity is exploited to create nanopores in PS-b-P4VP thin films. Both of these are multicomponent polymer systems which have nanoscale porous structures. 1. Small angle neutron scattering of micellization of anionic surfactants in water, polymer solutions and hydrogels. Nanoporous materials have been broadly investigated due to the potential for a wide range of applications, including nano-reactors, low-K materials, and membranes. Among those, molecularly imprinted polymers (MIP) have attracted a large amount of interest because these materials resemble the "lock and key" paradigm of enzymes. MIPs are created by crosslinking either polymers or monomers in the presence of template molecules, usually in water. Initially, functional groups on the polymer or the monomer are bound either covalently or noncovalently to the template, and crosslinking results in a highly crosslinked hydrogel. The MIPs containing templates are immersed in a solvent (usually water), and the large difference in the osmotic pressure between the hydrogel and solvent removes the template molecules from the MIP, leaving pores in the polymer network containing functionalized groups. A broad range of different templates have been used ranging from molecules to nanoscale structures inclucing stereoisomers, virus, and micelles. When micelles are used as templates, the size and shape before and after crosslinking is an important variable as micelles are thermodynamic objects whose structure depends on the surfactant concentration of the solution, temperature, electrolyte concentration and polymer concentration. In our research, the first goal is to understand the micellization of anionic

  8. Network confinement and heterogeneity slows nanoparticle diffusion in polymer gels

    Science.gov (United States)

    Parrish, Emmabeth; Caporizzo, Matthew A.; Composto, Russell J.

    2017-05-01

    Nanoparticle (NP) diffusion was measured in polyacrylamide gels (PAGs) with a mesh size comparable to the NP size, 21 nm. The confinement ratio (CR), NP diameter/mesh size, increased from 0.4 to 3.8 by increasing crosslinker density and from 0.4 to 2.1 by adding acetone, which collapsed the PAGs. In all gels, NPs either became localized, moving less than 200 nm, diffused microns, or exhibited a combination of these behaviors, as measured by single particle tracking. Mean squared displacements (MSDs) of mobile NPs decreased as CR increased. In collapsed gels, the localized NP population increased and MSD of mobile NPs decreased compared to crosslinked PAGs. For all CRs, van Hove distributions exhibited non-Gaussian displacements, consistent with intermittent localization of NPs. The non-Gaussian parameter increased from a maximum of 1.5 for crosslinked PAG to 5 for collapsed PAG, consistent with greater network heterogeneity in these gels. Diffusion coefficients decreased exponentially as CR increased for crosslinked gels; however, in collapsed gels, the diffusion coefficients decreased more strongly, which was attributed to network heterogeneity. Collapsing the gel resulted in an increasingly tortuous pathway for NPs, slowing diffusion at a given CR. Understanding how gel structure affects NP mobility will allow the design and enhanced performance of gels that separate and release molecules in membranes and drug delivery platforms.

  9. A HYBRID POLYMER GEL AND ITS STATIC NONERGODICIT

    Institute of Scientific and Technical Information of China (English)

    Yue Zhao; Chi Wu

    2002-01-01

    We used a thermally reversible hybrid gel made of billions of physically jam-packed swollen thermally sensitive poly(N-isopropyl-acrylamide) chemical microgels. Laser light scattering study on a series of such hybrid gels formed at different gelling rates and temperatures revealed that the position-dependence of the scattering speckle pattern (static nonergodicity) came from large voids formed during the sol-gel transition. With a proper preparation, such a nonergodicity could be completely removed, indicating that the static nonergodicity generally observed in a gel is not intrinsic, but comes from the clustering "island" structure formed during the gelation process.

  10. Three-dimensional dosimetry using magnetic resonance imaging of polymer gel

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Young Taek; Kang, Hae Jin; Kim, Mi Wha; Chun, Mi Son; Kang, Seung Hee [Ajou University School of Medicine, Suwon (Korea, Republic of); Suh, Chang Ok; Chu, Seong Sil; Seong, Jin Sil; Kim, Gwi Eon [Yonsei University College of Medicine, Seoul (Korea, Republic of)

    2002-09-15

    Three-dimensional radiation dosimetry using magnetic resonance imaging of polymer gel was recently introduced. This dosimetry system is based on radiation induced chain polymerization of acrylic monomers in a muscle equivalent gel and provide accurate 3 dimensional dose distribution. We planned this study to evaluate the clinical value of this 3-dimensional dosimetry. The polymer gel poured into a cylindrical glass flask and a spherical glass flask. The cylindrical test tubes were for dose response evaluation and the spherical flasks, which is comparable to the human head, were for isodose curves. T2 maps from MR images were calculated using software, IDL. Dose distributions have been displayed for dosimetry. The same spherical flask of gel and the same irradiation technique was used for film and TLD dosimetry and compared with each other. The R2 of the gel respond linearly with radiation doses in the range of 2 to 15 Gy. The repeated dosimetry of spherical gel showed the same isodose curves. The isodose curves were identical to dose distributions from treatment planning system especially high dose range. In addition, the gel dosimetry system showed comparable or superior results with the film and TLD dosimetry. The 3-dimensional dosimetry for conformal radiation therapy using MRI of polymer gel showed stable and accurate results. Although more studies are needed for convenient clinical application, it appears to be a useful tool for conformal radiation therapy.

  11. Honeycomb-like porous gel polymer electrolyte membrane for lithium ion batteries with enhanced safety

    Science.gov (United States)

    Zhang, Jinqiang; Sun, Bing; Huang, Xiaodan; Chen, Shuangqiang; Wang, Guoxiu

    2014-08-01

    Lithium ion batteries have shown great potential in applications as power sources for electric vehicles and large-scale energy storage. However, the direct uses of flammable organic liquid electrolyte with commercial separator induce serious safety problems including the risk of fire and explosion. Herein, we report the development of poly(vinylidene difluoride-co-hexafluoropropylene) polymer membranes with multi-sized honeycomb-like porous architectures. The as-prepared polymer electrolyte membranes contain porosity as high as 78%, which leads to the high electrolyte uptake of 86.2 wt%. The PVDF-HFP gel polymer electrolyte membranes exhibited a high ionic conductivity of 1.03 mS cm-1 at room temperature, which is much higher than that of commercial polymer membranes. Moreover, the as-obtained gel polymer membranes are also thermally stable up to 350°C and non-combustible in fire (fire-proof). When applied in lithium ion batteries with LiFePO4 as cathode materials, the gel polymer electrolyte demonstrated excellent electrochemical performances. This investigation indicates that PVDF-HFP gel polymer membranes could be potentially applicable for high power lithium ion batteries with the features of high safety, low cost and good performance.

  12. A thermal and electrochemical properties research on gel polymer electrolyte membrane of lithium ion battery

    Science.gov (United States)

    Li, Libo; Ma, Yue; Wang, Wentao; Xu, Yanping; You, Jun; Zhang, Yonghong

    2016-12-01

    N-methyl-N-propyl-piperidin-bis(trifluoromethylsulfonyl)imide/bis(trifluoromethylsulfonyl) imide lithium base/polymethyl methacrylate(PP13TFSI/LiTFSI/PMMA) gel polymer electrolyte (GPE) membrane was prepared by in situ polymerization. The physical and chemical properties were comprehensively discussed. The decomposition characteristics were emphasized by thermogravimetric (TG-DTG) method in the nitrogen atmosphere at the different heating rates of 5, 10, 15 and 20 °C min-1, respectively. The activation energy was calculated with the iso-conversional methods of Ozawa and Kissinger, Friedman, respectively, and the Coats-Redfern methods were adopted to employ the detailed mechanism of the electrolyte membrane. The equation f(α)=3/2[(1-α)1/3-1] was quite an appropriate kinetic mechanisms to describe the thermal decomposition process with an activation energy (Eα) of 184 kJ/mol and a pre-exponential factor (A) of 1.894×1011 were obtained.

  13. Influence of the Ionic Liquid Type on the Gel Polymer Electrolytes Properties.

    Science.gov (United States)

    Tafur, Juan P; Santos, Florencio; Romero, Antonio J Fernández

    2015-11-19

    Gel Polymer Electrolytes (GPEs) composed by ZnTf₂ salt, poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP), and different ionic liquids are synthesized using n-methyl-2-pyrrolidone (NMP) as solvent. Three different imidazolium-based ionic liquids containing diverse cations and anions have been explored. Structural and electrical properties of the GPEs varying the ZnTf₂ concentration are analyzed by ATR-FTIR, DSC, TG, and cyclic voltammetry. Free salt IL-GPEs present distinct behavior because they are influenced by the different IL cations and anions composition. However, inclusion of ZnTf₂ salt inside the polymers provide GPEs with very similar characteristics, pointing out that ionic transport properties are principally caused by Zn(2+) and triflate movement. Whatever the IL used, the presence of NMP solvent inside the polymer's matrix turns out to be a key factor for improving the Zn(2+) transport inside the GPE due to the interaction between Zn(2+) cations and carbonyl groups of the NMP. High values of ionic conductivity, low activation energy values, and good voltammetric reversibility obtained regardless of the ionic liquid used enable these GPEs to be applied in Zn batteries. Capacities of 110-120 mAh·g(-1) have been obtained for Zn/IL-GPE/MnO₂ batteries discharged at -1 mA·cm(-2).

  14. AN EXPERIMENTAL STUDY ON THE SOL/GEL PHASE TRANSITION OF LINEAR POLYMER IN THE PRESENCE OF CROSSLINKERS

    Institute of Scientific and Technical Information of China (English)

    HAN Ming; SHI Lianghe; YE Meiling; MULLER Guy

    1996-01-01

    The sol/gel phase diagrams were studied for two systems: polyacrylamide/Cr (Ⅲ) and polyacrylamide/glyoxal. Sol or gel phase could be distinguished according to the concentrations of polymer and crosslinker. The boundary polymer concentration did not depend on the types of gelation and decreased with increasing polymer dimension (molecular weight and conformation). The gelation, which is basically interchain bonding, requires the occurrence of entanglement. The overlap concentration is thus considered as the minimum polymer concentration required for gelation.

  15. Multi-Stimuli-Responsive Polymer Materials: Particles, Films, and Bulk Gels.

    Science.gov (United States)

    Cao, Zi-Quan; Wang, Guo-Jie

    2016-06-01

    Stimuli-responsive polymers have received tremendous attention from scientists and engineers for several decades due to the wide applications of these smart materials in biotechnology and nanotechnology. Driven by the complex functions of living systems, multi-stimuli-responsive polymer materials have been designed and developed in recent years. Compared with conventional single- or dual-stimuli-based polymer materials, multi-stimuli-responsive polymer materials would be more intriguing since more functions and finer modulations can be achieved through more parameters. This critical review highlights the recent advances in this area and focuses on three types of multi-stimuli-responsive polymer materials, namely, multi-stimuli-responsive particles (micelles, micro/nanogels, vesicles, and hybrid particles), multi-stimuli-responsive films (polymer brushes, layer-by-layer polymer films, and porous membranes), and multi-stimuli-responsive bulk gels (hydrogels, organogels, and metallogels) from recent publications. Various stimuli, such as light, temperature, pH, reduction/oxidation, enzymes, ions, glucose, ultrasound, magnetic fields, mechanical stress, solvent, voltage, and electrochemistry, have been combined to switch the functions of polymers. The polymer design, preparation, and function of multi-stimuli-responsive particles, films, and bulk gels are comprehensively discussed here.

  16. A flexible Li polymer primary cell with a novel gel electrolyte based on poly(acrylonitrile)

    Science.gov (United States)

    Akashi, Hiroyuki; Tanaka, Ko-ichi; Sekai, Koji

    The performance of a Li polymer primary cell with fire-retardant poly(acrylonitrile) (PAN)-based gel electrolytes is reported. By optimizing electrodes, electrolytes, the packaging material, and the structural design of the polymer cell, we succeeded in developing a "film-like" Li polymer primary cell with sufficient performance for practical use. The cell is flexible and less than 0.5 mm thick, which makes it suitable for a power source for some smart devices, such as an IC card. Fast cation conduction in the gel electrolyte minimizes the drop of the discharge capacity even at -20 °C. The high chemical stability of the gel electrolytes and the new packaging material allow the self-discharge rate to be limited to under 4.3%, which is equivalent to that of conventional coin-shaped or cylindrical Li-MnO 2 cells.

  17. Stable Lithium Deposition Generated from Ceramic-Cross-Linked Gel Polymer Electrolytes for Lithium Anode.

    Science.gov (United States)

    Tsao, Chih-Hao; Hsiao, Yang-Hung; Hsu, Chun-Han; Kuo, Ping-Lin

    2016-06-22

    In this work, a composite gel electrolyte comprising ceramic cross-linker and poly(ethylene oxide) (PEO) matrix is shown to have superior resistance to lithium dendrite growth and be applicable to gel polymer lithium batteries. In contrast to pristine gel electrolyte, these nanocomposite gel electrolytes show good compatibility with liquid electrolytes, wider electrochemical window, and a superior rate and cycling performance. These silica cross-linkers allow the PEO to form the lithium ion pathway and reduce anion mobility. Therefore, the gel not only features lower polarization and interfacial resistance, but also suppresses electrolyte decomposition and lithium corrosion. Further, these nanocomposite gel electrolytes increase the lithium transference number to 0.5, and exhibit superior electrochemical stability up to 5.0 V. Moreover, the lithium cells feature long-term stability and a Coulombic efficiency that can reach 97% after 100 cycles. The SEM image of the lithium metal surface after the cycling test shows that the composite gel electrolyte with 20% silica cross-linker forms a uniform passivation layer on the lithium surface. Accordingly, these features allow this gel polymer electrolyte with ceramic cross-linker to function as a high-performance lithium-ionic conductor and reliable separator for lithium metal batteries.

  18. Novel Amphiphilic Polymer Gel Electrolytes Based on PEG-b-GMA-co-MMA

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    1 Results Gel polymer electrolytes for lithium battery have been widely investigated recently because of their high ion conductivity at room temperature. We synthesized and characterized novel gel electrolytes based on amphiphilic copolymethacrylates containing different lengths of ethylene oxide (EO) chain as ionophilic units and methyl methacrylate (MMA) chain as ionophobic units[1]. Their electrochemical properties were also measured.1H NMR and FTIR analysis results elucidated that PEG-b-glycidyl met...

  19. Mixed Pyridine-phenol Boron Complex Encapsulated in Polymer/Silica Hybrid Sol-gel Matrix

    Institute of Scientific and Technical Information of China (English)

    DONG Wei; TANG Jun; WANG Yue

    2008-01-01

    A novel pyridine-phenol boron complex[(dppy)BF]was encapsulated into polymer/silica composite matrix by sol-gel process.UV-Vis absorption spectra show that this process can control the aggregation structure of complex(dppy)BF.The results of photoluminescence of(dppy)BF in sol-gel composite film indicate that both fluorescence intensity and photostability are markedly increased using this method compared with other methods,which increases the practical significance of such composite film.

  20. Gel Formation in Polymers Undergoing Radiation-Induced Crosslinking and Scission

    DEFF Research Database (Denmark)

    Handlos, V. N.; Singer, Klaus Albert Julius

    1976-01-01

    A study was made of the solubility of irradiated polyethylene. The experimental data were treated according to the Saito-Inokuti theory for gel formation in polymers exposed to ionizing radiation. Among other things, this theory is based upon the molecular weight distribution of the unirradiated...... polymer; in the present work, the actual distributions were determined by high-temperature gel permeation chromatography and corrected for long-chain branching. Under these circumstances, good agreement between theory and experimental data was obtained, which allowed the determination of the radiation...

  1. A Demonstration of Polymer Crosslinking and Gel Formation Without Heating

    Science.gov (United States)

    Ross, Joseph H.

    1977-01-01

    Describes an undergraduate experiment in which Gantrez AN polymer chains are crosslinked at the anhydride groups by the addition of the hydroxyl groups of triethanolamine, which also acts as a basic catalyst. (MLH)

  2. Dosimetric Evaluation of Linac Photon Small Fields using MAGIC Polymer Gels

    Directory of Open Access Journals (Sweden)

    Hossein Hasani

    2011-09-01

    Full Text Available Introduction: In radiotherapy, methods of treatment planning are becoming increasingly more complicated. This requires verification of the doses delivered to increasingly smaller and more precise regions. Radiotherapy techniques are continuously employing smaller and smaller field sizes to deliver tighter radiation doses with higher therapeutic ratios, generating interest among researchers to provide reliable dosimetry for beams and treatment plans collimated to small field sizes. In this study, the dosimetry of these fields was evaluated in clinical applications by using polymer gel dosimetry. Material and Methods: The MAGIC polymer gel was used in this study. The gel samples were manufactured and poured into phantoms and calibration vials and were irradiated with a 6 MV x-ray beam. The R2 maps of the dose distributions were obtained from the gel MR images. The depth dose distributions and dose profile measurements were measured in different fields at a depth of 5 cm in gel, and were compared against another technique using a pinpoint chamber. Results: Comparison of the results of gel and pinpoint chamber measurements showed largest differences between the dose profile measurements in the low dose regions (near the edges. In these regions, the pinpoint-chamber measured penumbra width was at most 3.2 mm wider than those given by gel dosimeters. For a 30 × 30 mm2 field, maximum difference between gel and pinpoint chamber was 2 mm within the depth of maximum dose region, and were 2 mm, 3 mm and 2 mm for 20 × 20 mm2, 10 × 10 mm2 and 5 × 5 mm2 fields, respectively. The maximum differences within the buildup region for 30 × 30 mm2, 20 × 20 mm2, 10 × 10 mm2 and 5 × 5 mm2 fields were 9%, 4.5%, 2% and 9%, respectively. Discussion and Conclusion: The differences in the depth dose distributions and dose profile measurements between MAGIC polymer gel and pinpoint chamber are attributable to different factors. The dosimetry of these fields using

  3. Polymer Physics Prize: Designing ''Materials that Compute'': Exploiting the Properties of Self-oscillating Polymer Gels

    Science.gov (United States)

    Balazs, Anna

    Lightweight, deformable materials that can sense and respond to human touch and motion can be the basis of future wearable computers, where the material itself will be capable of performing computations. To facilitate the creation of ''materials that compute'', we draw from two emerging modalities for computation: chemical computing, which relies on reaction-diffusion mechanisms to perform operations, and oscillatory computing, which performs pattern recognition through synchronization of coupled oscillators. Chemical computing systems, however, suffer from the fact that the reacting species are coupled only locally; the coupling is limited by diffusion as the chemical waves propagate throughout the system. Additionally, oscillatory computing systems have not utilized a potentially wearable material. To address both these limitations, we develop the first model for coupling self-oscillating polymer gels to a piezoelectric (PZ) micro-electro-mechanical system (MEMS). The resulting transduction between chemo-mechanical and electrical energy creates signals that can be propagated quickly over long distances and thus, permits remote, non-diffusively coupled oscillators to communicate and synchronize. The oscillators can be organized into arbitrary topologies because the electrical connections lift the limitations of diffusive coupling. Using our model, we predict the synchronization behavior that can be used for computational tasks, ultimately enabling ''materials that compute''.

  4. Hemoglobin-imprinted polymer gel prepared using modified glucosamine as functional monomer

    Institute of Scientific and Technical Information of China (English)

    Hai Li Zhao; Tian Ying Guo; Yong Qing Xia; Mou Dao Song

    2008-01-01

    A new functional glycomonomer was obtained from modified glucosamine.Hemoglobin-imprinted polymer gel was prepared with allyl-bromide modified glucosamine as functional monomer,poly(ethylene-glycol)diaorylate(PEGDA)as cross-linker and ammonium persulfate[(NH4)2S2O8]/sodium hydrogen sulfite(NaHSO3)as initiators in a phosphate buffer.The adsorption capacity and selective adsorption of the molecular imprinting polymer(MIP)were also discussed.

  5. Comparison of non-electrophoresis grade with electrophoresis grade BIS in NIPAM polymer gel preparation.

    Science.gov (United States)

    Khodadadi, Roghayeh; Khajeali, Azim; Farajollahi, Ali Reza; Hajalioghli, Parisa; Raeisi, Noorallah

    2015-01-01

    The main objective of this study was to investigate the possibility of replacing electrophoresis cross-linker with non-electrophoresis N, N'-methylenebisacrylamide (BIS) in N-isopropyl acrylamide (NIPAM) polymer gel and its possible effect on dose response. NIPAM polymer gel was prepared from non-electrophoresis grade BIS and the relaxation rate (R2) was measured by MR imaging after exposing the gel to gamma radiation from Co-60 source. To compare the response of this gel with the one that contains electrophoresis grade BIS, two sets of NIPAM gel were prepared using electrophoresis and non-electrophoresis BIS and irradiated to different gamma doses. It was found that the dose-response of NIPAM gel made from the non-electrophoresis grade BIS is coincident with that of electrophoresis grade BIS. Taken all, it can be concluded that the non-electrophoresis grade BIS not only is a suitable alternative for the electrophoresis grade BIS but also reduces the cost of gel due to its lower price.

  6. DEVELOPMENT OF POLYMER GEL SYSTEMS TO IMPROVE VOLUMETRIC SWEEP AND REDUCE PRODUCING WATER/OIL RATIOS

    Energy Technology Data Exchange (ETDEWEB)

    G. Paul Willhite; Stan McCool; Don W. Green; Min Cheng; Rajeev Jain; Tuan Nguyen

    2003-11-01

    Gelled polymer treatments are applied to oil reservoirs to increase oil production and to reduce water production by altering the fluid movement within the reservoir. This report describes the results of the first year of a three-year research program that is aimed at the understanding of the chemistry of gelation and the fundamental mechanisms that alter the flows of oil and water in reservoir rocks after a gel treatment. Work has focused on a widely-applied system in field applications, the partially hydrolyzed polyacrylamide-chromium acetate gel. Gelation occurs by network formation through the crosslinking of polyacrylamide molecules as a result of reaction with chromium acetate. The initial reaction between chromium acetate and one polymer is referred to as the uptake reaction. The uptake reaction was studied as functions of chromium and polymer concentrations and pH values. Experimental data were regressed to determine a rate equation that describes the uptake reaction of chromium by polyacrylamide. Pre-gel aggregates form and grow as the reactions between chromium acetate and polyacrylamide proceed. A statistical model that describes the growth of pre-gel aggregates was developed using the theory of branching processes. The model gives molecular weight averages that are expressed as functions of the conversion of the reactive sites on chromium acetate or on the polymer molecule. Results of the application of the model correlate well with experimental data of viscosity and weight-average molecular weight and gives insights into the gelation process. A third study addresses the flow of water and oil in rock material after a gel treatment. Previous works have shown that gel treatments usually reduce the permeability to water to a greater extent than the permeability to oil is reduced. This phenomenon is referred to as disproportionate permeability reduction (DPR). Flow experiments were conducted to determine the effect of polymer and chromium concentrations on

  7. Enhancement in dose sensitivity of polymer gel dosimeters composed of radiation-crosslinked gel matrix and less toxic monomers

    Science.gov (United States)

    Hiroki, A.; Yamashita, S.; Taguchi, M.

    2015-01-01

    Polymer gel dosimeters based on radiation-crosslinked hydroxypropyl cellulose gel were prepared, which comprised 2-hydroxyethyl methacrylate (HEMA) and polyethylene glycol #400 dimethacrylate (9G) as less toxic monomers and tetrakis (hydroxymethyl) phosphonium chloride (THPC) as an antioxidant. The dosimeters exposed to 60Co γ-rays became cloudy at only 1 Gy. The irradiated dosimeters were optically analyzed by using a UV- vis spectrophotometer to evaluate dose response. Absorbance of the dosimeters linearly increased in the dose range from 0 to 10 Gy, in which dose sensitivity increased with increasing 9G concentration. The dose sensitivity of the dosimeters with 2 wt% HEMA and 3 wt% 9G was also enhanced by increment in THPC.

  8. High efficiency dye-sensitized nanocrystalline solar cells based on ionic liquid polymer gel electrolyte.

    Science.gov (United States)

    Wang, Peng; Zakeeruddin, Shaik M; Exnar, Ivan; Grätzel, Michael

    2002-12-21

    An ionic liquid polymer gel containing 1-methyl-3-propylimidazolium iodide (MPII) and poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) has been employed as quasi-solid-state electrolyte in dye-sensitized nanocrystalline TiO2 solar cells with an overall conversion efficiency of 5.3% at AM 1.5 illumination.

  9. Influence of the Ionic Liquid Type on the Gel Polymer Electrolytes Properties

    Directory of Open Access Journals (Sweden)

    Juan P. Tafur

    2015-11-01

    Full Text Available Gel Polymer Electrolytes (GPEs composed by ZnTf2 salt, poly(vinylidene fluoride-co-hexafluoropropylene (PVdF-HFP, and different ionic liquids are synthesized using n-methyl-2-pyrrolidone (NMP as solvent. Three different imidazolium-based ionic liquids containing diverse cations and anions have been explored. Structural and electrical properties of the GPEs varying the ZnTf2 concentration are analyzed by ATR-FTIR, DSC, TG, and cyclic voltammetry. Free salt IL-GPEs present distinct behavior because they are influenced by the different IL cations and anions composition. However, inclusion of ZnTf2 salt inside the polymers provide GPEs with very similar characteristics, pointing out that ionic transport properties are principally caused by Zn2+ and triflate movement. Whatever the IL used, the presence of NMP solvent inside the polymer’s matrix turns out to be a key factor for improving the Zn2+ transport inside the GPE due to the interaction between Zn2+ cations and carbonyl groups of the NMP. High values of ionic conductivity, low activation energy values, and good voltammetric reversibility obtained regardless of the ionic liquid used enable these GPEs to be applied in Zn batteries. Capacities of 110–120 mAh·g−1 have been obtained for Zn/IL-GPE/MnO2 batteries discharged at −1 mA·cm−2.

  10. Novel composition of polymer gel dosimeters based on N-(Hydroxymethyl)acrylamide for radiation therapy

    Science.gov (United States)

    Basfar, Ahmed A.; Moftah, Belal; Rabaeh, Khalid A.; Almousa, Akram A.

    2015-07-01

    A new composition of polymer gel dosimeters is developed based on radiation induced polymerization of N-(Hydroxymethyl)acrylamide (NHMA) for radiotherapy treatment planning. The dosimeters were irradiated by 10 MV photon beam of a medical linear accelerator at a constant dose rate of 600 cGy/min with doses up to 20 Gy. The polymerization occurs and increases with increasing absorbed dose. The dose response of polymer gel dosimeters was studied using nuclear magnetic imaging (NMR) for relaxation rate (R2) of water proton. Dose rate, energy of radiation and the stability of the polymerization after irradiation were investigated. No appreciable effects of these parameters on the performance of the novel gel dosimeters were observed.

  11. New normoxic N-(Hydroxymethyl)acrylamide based polymer gel for 3D dosimetry in radiation therapy.

    Science.gov (United States)

    Rabaeh, Khalid A; Basfar, Ahmed A; Almousa, Akram A; Devic, Slobodan; Moftah, Belal

    2017-01-01

    A novel composition of normoxic polymer gel dosimeters based on radiation-induced polymerization of N-(Hydroxymethyl)acrylamide (NHMA) is introduced in this study for 3D dosimetry for Quality Assurance (QA) in radiation therapy. Dosimeters were irradiated by 6, 10 and 18MV photon beams of a medical linear accelerator at various dose rates to doses of up to 20Gy. The dose response of polymer gel dosimeters was studied using nuclear magnetic resonance (NMR) spin-spin relaxation rate (R2) of hydrogen protons within the water molecule. Also, we measured gel response using absorption spectroscopy and found that this novel gel can be successfully utilized for both MRI- and OCT- (Optical Computed Tomography) based 3D dosimetry. We investigated dosimetric properties of six different compositions of the new NHMA-based gel in terms of dose rate, radiation beam quality and stability of dose-dependent polymerization after irradiation. We found no significant effects of these parameters on the novel gel dosimeter performance in both relaxation rate and absorbance measurements.

  12. Design and construction of an optical computed tomography scanner for polymer gel dosimetry application.

    Science.gov (United States)

    Zakariaee, Seyed Salman; Mesbahi, Asghar; Keshtkar, Ahmad; Azimirad, Vahid

    2014-04-01

    Polymer gel dosimeter is the only accurate three dimensional (3D) dosimeter that can measure the absorbed dose distribution in a perfect 3D setting. Gel dosimetry by using optical computed tomography (OCT) has been promoted by several researches. In the current study, we designed and constructed a prototype OCT system for gel dosimetry. First, the electrical system for optical scanning of the gel container using a Helium-Neon laser and a photocell was designed and constructed. Then, the mechanical part for two rotational and translational motions was designed and step motors were assembled to it. The data coming from photocell was grabbed by the home-built interface and sent to a personal computer. Data processing was carried out using MATLAB software. To calibrate the system and tune up the functionality of it, different objects was designed and scanned. Furthermore, the spatial and contrast resolution of the system was determined. The system was able to scan the gel dosimeter container with a diameter up to 11 cm inside the water phantom. The standard deviation of the pixels within water flask image was considered as the criteria for image uniformity. The uniformity of the system was about ±0.05%. The spatial resolution of the system was approximately 1 mm and contrast resolution was about 0.2%. Our primary results showed that this system is able to obtain two-dimensional, cross-sectional images from polymer gel samples.

  13. DEVELOPMENT OF POLYMER GEL SYSTEMS TO IMPROVE VOLUMETRIC SWEEP AND REDUCE PRODUCING WATER/OIL RATIOS

    Energy Technology Data Exchange (ETDEWEB)

    G. Paul Willhite; Don W. Green; Stan McCool; Min Cheng; Feiyan Chen

    2004-02-01

    The objectives of the research are to improve the effectiveness of polymer gels to increase volumetric sweep efficiency of fluid displacement processes and to reduce water production in production wells. The research is based on experimental data and conceptual and mathematical models developed from interpretation of experimental data. This report describes two types of mathematical models that were developed. One model type simulates the chemical reactions where polymer molecules are crosslinked to form a 3-dimensional network or gel. The model is based on statistical probabilities of reactions and yields molecular weights averages and distributions as functions of conversion. The second model type simulates the transport of chromium acetate, a common polymer crosslinker, through porous dolomite rock and includes the mechanisms of dolomite dissolution and chromium precipitation. The chromium transport model reasonably agreed with experimental data.

  14. Lipophilic polyelectrolyte gels as super-absorbent polymers for nonpolar organic solvents.

    Science.gov (United States)

    Ono, Toshikazu; Sugimoto, Takahiro; Shinkai, Seiji; Sada, Kazuki

    2007-06-01

    Polyelectrolyte gels that are known as super-absorbent polymers swell and absorb water up to several hundred times their dried weights and have become ubiquitous and indispensable materials in many applications. Their superior swelling abilities originate from the electrostatic repulsion between the charges on the polymer chains and the osmotic imbalance between the interior and exterior of the gels. However, no super-absorbent polymers for volatile organic compounds (VOCs), and especially for nonpolar organic solvents (epsilonpolymer networks. This expands the potential of polyelectrolytes that have been used only in aqueous solutions or highly polar solvents, and provides soft materials that swell in a variety of media. These materials could find applications as protective barriers for VOCs spilled in the environment and as absorbents for waste oil.

  15. On the mechanical characterization and modeling of polymer gel brain substitute under dynamic rotational loading.

    Science.gov (United States)

    Fontenier, B; Hault-Dubrulle, A; Drazetic, P; Fontaine, C; Naceur, H

    2016-10-01

    The use of highly sensitive soft materials has become increasingly apparent in the last few years in numerous industrial fields, due to their viscous and damping nature. Unfortunately these materials remain difficult to characterize using conventional techniques, mainly because of the very low internal forces supported by these materials especially under high strain-rates of deformation. The aim of this work is to investigate the dynamic response of a polymer gel brain analog material under specific rotational-impact experiments. The selected polymer gel commercially known as Sylgard 527 has been studied using a specific procedure for its experimental characterization and numerical modeling. At first an indentation experiment was conducted at several loading rates to study the strain rate sensitivity of the Sylgard 527 gel. During the unloading several relaxation tests were performed after indentation, to assess the viscous behavior of the material. A specific numerical procedure based on moving least square approximation and response surface method was then performed to determine adequate robust material parameters of the Sylgard 527 gel. A sensitivity analysis was assessed to confirm the robustness of the obtained material parameters. For the validation of the obtained material model, a second experiment was conducted using a dynamic rotational loading apparatus. It consists of a metallic cylindrical cup filled with the polymer gel and subjected to an eccentric transient rotational impact. Complete kinematics of the cup and the large strains induced in the Sylgard 527 gel, have been recorded at several patterns by means of optical measurement. The whole apparatus was modeled by the Finite Element Method using explicit dynamic time integration available within Ls-dyna(®) software. Comparison between the physical and the numerical models of the Sylgard 527 gel behavior under rotational choc shows excellent agreements.

  16. Effect of poly(ethylene oxide) on ionic conductivity and electrochemical properties of poly(vinylidenefluoride) based polymer gel electrolytes prepared by electrospinning for lithium ion batteries

    Science.gov (United States)

    Prasanth, Raghavan; Shubha, Nageswaran; Hng, Huey Hoon; Srinivasan, Madhavi

    2014-01-01

    Effect of poly(ethylene oxide) on the electrochemical properties of polymer electrolyte based on electrospun, non-woven membrane of PVdF is demonstrated. Electrospinning process parameters are controlled to get a fibrous membrane consisting of bead-free, uniformly dispersed thin fibers with diameter in the range of 1.5-1.9 μm. The membrane with good mechanical strength and porosity exhibits high uptake when activated with the liquid electrolyte of lithium salt in a mixture of organic solvents. The polymer gel electrolyte shows ionic conductivity of 4.9 × 10-3 S cm-1 at room temperature. Electrochemical performance of the polymer gel electrolyte is evaluated in Li/polymer electrolyte/LiFePO4 coin cell. Good performance with low capacity fading on charge-discharge cycling is demonstrated.

  17. Flow of oil and water through elastic polymer gels; Ecoulement de petrole et d'eau a travers des gels de polymere elastiques

    Energy Technology Data Exchange (ETDEWEB)

    Al-Sharji, H.H.; Grattoni, C.A.; Zimmerman, R.W. [T.H. Huxley School of Environment, Earth Sciences and Engineering, Imperial College of Science, Technology and Medecine, London (United Kingdom); Dawe, R.A. [West Indies Univ., Dept. of Chemical Engineering, Mona (Jamaica)

    2001-07-01

    High water production is one of the major problems faced by the petroleum industry. One method of controlling water production is to inject polymer gels into the near-wellbore formation. Unfortunately, polymer gel injections are not always successful, in part because the exact mechanisms by which they reduce water permeability more than oil permeability (i.e., Disproportionate Permeability Reduction. DPR) are not understood. We have conducted a series of experiments on flow of water and oil through bulk polymer gels and through polymer- filled micro-models to elucidate the fundamental mechanisms involved in DPR. Flow experiments of oil and water through weak polyacrylamide-based gels have been per,formed to obtain the gel permeabilities under different test conditions. Oil and water permeabilities through the gel were each found to vary with flow rate according to a power-law, but with different pre-factors and exponents. The micro-scale flow experiments were conducted in transparent glass models to visualize clearly the flow events. Our observations enabled us to discount many previously-proposed explanations, and identify the fact that the oil and water can travel through the same pore channels, but in ways that differ, particularly at the pore scale. Water flows through the gel matrix as if flowing by diffusive flow through a porous medium, whereas the oil pushes its way In the form of immiscible drops or filaments. This difference in flow regime gives rise to the measured disproportionate permeability reduction. (authors)

  18. Electrochemical characterization of poly(ethylene-co-methyl acrylate)-based gel polymer electrolytes for lithim-ion polymer batteries

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Won [Samsung Advanced Inst. of Technology, Daejon (Korea). Electrochemistry Lab.

    2000-04-01

    Gel polymer electrolytes (GPE) composed of poly(ethylene-co-methyl acrylate) copolymer, LiBF{sub 4}-EC/EMC/PC, and silanized fumed silica are prepared. The ionic conductivity reaches 5.8x10{sup -4} S cm{sup -1} in the GPE containing 22% poly(ethylene-co-methyl acrylate), 65% LiBF{sub 4}-EC/EMC/PC and 13% silanized fumed silica at room temperature. GPEs are free-standing films and are used to prepare thin films for rechargeable lithium-ion polymer cells. Lithium-ion polymer cells, which consist of mesophase carbon fibre anode, poly(ethylene-co-methyl acrylate)-based GPE and LiCoO{sub 2} cathode, are assembled, and their charge-discharge cycling characteristics are investigated. (orig.)

  19. Synthesis and characterization of polymer-silica hybrid latexes and sol-gel-derived films

    Science.gov (United States)

    Petcu, Cristian; Purcar, Violeta; Ianchiş, Raluca; Spătaru, Cătălin-Ilie; Ghiurea, Marius; Nicolae, Cristian Andi; Stroescu, Hermine; Atanase, Leonard-Ionuţ; Frone, Adriana Nicoleta; Trică, Bogdan; Donescu, Dan

    2016-12-01

    Sol-gel derived organic-inorganic hybrid systems were obtained by applying alkaline-catalyzed co-hydrolysis and copolycondensation reactions of tetraethoxysilane (TEOS), methyltriethoxysilane (MTES), isobutyltriethoxysilane (IBTES), diethoxydimethylsilane (DMDES), and vinyltriethoxysilane (VTES), respectively, into a polymer latex functionalized with vinyltriethoxysilane (VTES). The properties of the latex hybrid materials were analyzed by FTIR, water contact angle, environmental scanning electron microscopy (ESEM), TEM and AFM analysis, respectively. FT-IR spectra confirmed that the chemical structures of the sol-gel derived organic-inorganic materials are changed as function of inorganic precursor and Sisbnd Osbnd Si networks are formed during the co-hydrolysis and copolycondensation reactions. The water contact angle on the sol-gel latex film containing TEOS + VTES increased to 135° ± 2 compared to 65° ± 5 for the blank latex, due VTES incorporation into latex material. TGA curves of hybrid sample modifies against neat polymer, the thermal stability being influenced by the presence of the inorganic partner. ESEM analysis showed that the latex hybrid films prepared with different inorganic precursors were formed and the Si-based polymers were distributed on the surface of the dried sol-gel hybrid films. TEM and AFM photos revealed that the latex emulsion morphology was modified due to the VTES incorporation into system.

  20. Responsive Hydrogels and Ion Gels by Self-Assembly of ABA and ABC Triblock Polymers

    Science.gov (United States)

    Lodge, Timothy

    2014-03-01

    Gels - polymeric networks swollen with a substantial amount of solvent - represent a fascinating class of soft materials, with wide-ranging applications in fields as diverse as biomedicine, pharmaceutics, personal care products, foods, sensors, actuators, flexible electronics, oil recovery, and adhesives. Physical gels are held together by non-covalent interactions, which may be as specific as hydrogen bonds, or as general as solvophobic association of insoluble blocks. Among the attractive features of physical gels are reversibility, stimuli-responsiveness, and tunability of macroscopic properties. In this talk two classes of physical gels will be highlighted. In one, the ability of ABC block terpolymers to form novel structures will be demonstrated, where blocks A and C are mutually immiscible and solvophobic, while B is solvophilic. In particular, the formation of gels by sequential association (first A, then C) leads to a remarkably sharp gelation transition, at a relatively low polymer concentration, compared to analogous gels formed from ABA systems. In the second class, gels formed by self-assembly of a variety of ABA systems in ionic liquids will be described, and in particular how gelation can be controlled through factors such as block chemistry, temperature, choice of ionic liquid, and application of light.

  1. In-phantom dosimetry for BNCT with Fricke and normoxic-polymer gels

    Science.gov (United States)

    Gambarini, G.; Agosteo, S.; Carrara, M.; Gay, S.; Mariani, M.; Pirola, L.; Vanossi, E.

    2006-05-01

    Measurements of in-phantom dose distributions and images are important for Boron Neutron Capture Therapy treatment planning. The method for spatial determination of absorbed doses in thermal or epithermal neutron fields, based on Fricke-xylenol-orange-infused gel dosimeters in form of layers, has revealed to be very reliable, as gel layer dosimeters give the possibility of obtaining spatial dose distributions and measurements of each dose contribution in neutron fields, by means of a properly studied procedure. Quite recently, BNCT has been applied to treat liver metastases; in this work the results of in-phantom dosimetry for explanted liver in BNCT treatments are described. Moreover, polyacrylamide gel (PAG) dosimeters in which a polymerization process appears as a consequence of absorbed dose, have been recently tested, because of their characteristic absence of diffusion. In fact, due to the diffusion of ferric ions, Fricke-gel dosimeters require prompt analysis after exposure to avoid spatial information loss. In this work the preliminary results of a study about the reliability of polymer gel in BNCT dosimetry are also discussed. Gel layers have been irradiated in a phantom exposed in the thermal column of the TRIGA MARK II reactor (Pavia). The results obtained with the two kinds of gel dosimeter have been compared.

  2. Photon and neutron kerma coefficients for polymer gel dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    El-Khayatt, A.M., E-mail: Ahmed_el_khayatt@yahoo.com [Physics Department, College of Science, Al Imam Mohammad Ibn Saud Islamic University (IMSIU) (Saudi Arabia); Reactor Physics Department, Nuclear Research Centre, Atomic Energy Authority, 13759 Cairo (Egypt); Vega-Carrillo, Hector Rene [Unidad Academica de Estudios Nucleares, Universidad Autonoma de Zacatecas, C. Cipres 10, Fracc. La Peñuela, 98068 Zacatecas, Zac. (Mexico)

    2015-08-21

    Neutron and gamma ray kerma coefficients were calculated for 17 3D dosimeters, for the neutron and gamma ray energy ranges extend from 2.53×10{sup −8} to 29 MeV and from 1.0×10{sup −3} to 20 MeV, respectively. The calculated kermas given here for discrete energies and the kerma coefficients are referred to as “point-wise data”. Curves of gamma ray kermas showed slight dips at about 60 keV for most 3D dosimeters. Also, a noticeable departure between thermal and epithermal neutrons kerma sets for water and polymers has been observed. Finally, the obtained results could be useful for dose estimation in the studied 3D dosimeters. - Highlights: • Neutron and gamma ray kerma coefficients were calculated in 17 3D dosimeters. • Curves of gamma-ray kermas showed slight dips at about 60 keV. • Disagreement between neutron kermas for water and polymers has been observed. • The obtained results could be useful for dose estimation in the studied dosimeters.

  3. Structural and electrochemical properties of succinonitrile-based gel polymer electrolytes: role of ionic liquid addition.

    Science.gov (United States)

    Suleman, Mohd; Kumar, Yogesh; Hashmi, S A

    2013-06-20

    Experimental studies on the novel compositions of gel polymer electrolytes, comprised of plastic crystal succinonitrile (SN) dispersed with pyrrolidinium and imidazolium-based ionic liquids (ILs) entrapped in a host polymer poly(vinylidine fluoride-co-hexafluoropropylene) (PVdF-HFP), are reported. The gel electrolytes are in the form of free-standing films with excellent mechanical, thermal, and electrochemical stability. The introduction of even a small content (~1 wt %) of ionic liquid (1-butyl-1-methylpyrrolidinium bis(trifluoromethyl-sulfonyl)imide (BMPTFSI) or 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMITf) in the PVdF-HFP/SN system (1:4 w/w) enhances the electrical conductivity by 4 orders of magnitude, that is, from ~10(-7) to ~10(-3) S cm(-1) at room temperature. The structural changes due to the entrapment of SN or SN/ILs mixtures and ion-SN-polymer interactions are examined by Fourier transform infrared (FTIR)/Raman spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimmetry (DSC). Various physicochemical properties and fast ion conduction in the gel polymer membranes show their promising characteristics as electrolytes in different ionic devices including supercapacitors.

  4. Effect of conductive additives to gel electrolytes on activated carbon-based supercapacitors

    Directory of Open Access Journals (Sweden)

    Farshad Barzegar

    2015-09-01

    Full Text Available This article is focused on polymer based gel electrolyte due to the fact that polymers are cheap and can be used to achieve extended potential window for improved energy density of the supercapacitor devices when compared to aqueous electrolytes. Electrochemical characterization of a symmetric supercapacitor devices based on activated carbon in different polyvinyl alcohol (PVA based gel electrolytes was carried out. The device exhibited a maximum energy density of 24 Wh kg−1 when carbon black was added to the gel electrolyte as conductive additive. The good energy density was correlated with the improved conductivity of the electrolyte medium which is favorable for fast ion transport in this relatively viscous environment. Most importantly, the device remained stable with no capacitance lost after 10,000 cycles.

  5. Highly compliant shape memory polymer gels for tunable damping and reversible adhesion

    Science.gov (United States)

    Mrozek, Randy A.; Berg, Michael C.; Gold, Christopher S.; Leighliter, Brad; Morton, Jeffrey T.; Lenhart, Joseph L.

    2016-02-01

    Materials that can dynamically change their properties to better adapt to the local environment have potential utility in robotics, aerospace, and coatings. For some of these applications, most notably robotics, it is advantageous for these responsive materials to be highly compliant in an effort to provide dynamic changes in adhesion and mechanical damping within a broad temperature operational environment. In this report, non-aqueous, highly compliant shape-memory polymer gels are developed by incorporating a low density of chemical cross-links into a physically cross-linked thermoplastic elastomer gel. Chemical cross-linkers were evaluated by varying there size and degree of functionality to determine the impact on the mechanical and adhesive properties. As a result of the chemical cross-linking, the gels exhibit modulus plateaus around room temperature and at elevated temperatures above 100 °C, where the thermoplastic elastomer gel typically melts. The materials were designed so that moduli in the plateaued regions were above and below the Dahlquist criteria of 4 × 104 Pa, respectively, where materials with a modulus below this value typically exhibit an increase in adhesion. The shape memory polymer gels were also integrated into fiber-reinforced composites to determine the temperature-dependent changes in mechanical damping. It is anticipated that this work will provide insight into materials design to provide dynamic changes in adhesion and damping to improve robotic appendage manipulation and platform mobility.

  6. A Comprehensive Evaluation of NIPAM Polymer Gel Dosimeters on Three Orthogonal Planes and Temporal Stability Analysis.

    Directory of Open Access Journals (Sweden)

    Kai-Yuan Cheng

    Full Text Available Polymer gel dosimeters have been proven useful for dose evaluation in radiotherapy treatments. Previous studies have demonstrated that using a polymer gel dosimeter requires a 24 h reaction time to stabilize and further evaluate the measured dose distribution in two-dimensional dosimetry. In this study, the short-term stability within 24 h and feasibility of N-isopropylacrylamide (NIPAM polymer gel dosimeters for use in three-dimensional dosimetry were evaluated using magnetic resonance imaging (MRI. NIPAM gels were used to measure the dose volume in a clinical case of intensity-modulated radiation therapy (IMRT. For dose readouts, MR images of irradiated NIPAM gel phantoms were acquired at 2, 5, 12, and 24 h after dose delivery. The mean standard errors of dose conversion from using dose calibration curves (DRC were calculated. The measured dose volumes at the four time points were compared with those calculated using a treatment planning system (TPS. The mean standard errors of the dose conversion from using the DRCs were lower than 1 Gy. Mean pass rates of 2, 5, 12, and 24 h axial dose maps calculated using gamma evaluation with 3% dose difference and 3 mm distance-to-agreement criteria were 83.5% ± 0.9%, 85.9% ± 0.6%, 98.7% ± 0.3%, and 98.5% ± 0.9%, respectively. Compared with the dose volume histogram of the TPS, the absolute mean relative volume differences of the 2, 5, 12, and 24 h measured dose volumes were lower than 1% for the irradiated region with an absorbed dose higher than 2.8 Gy. It was concluded that a 12 h reaction time was sufficient to acquire accurate dose volume using the NIPAM gels with MR readouts.

  7. Effect of Polymers (PEG and PVP on Sol-Gel Synthesis of Microsized Zinc Oxide

    Directory of Open Access Journals (Sweden)

    Thilagavathi Thirugnanam

    2013-01-01

    Full Text Available Fibers irregular and seed-like microcrystalline ZnO were synthesized by using a cost-effective and low temperature aqueous sol-gel method. Various polymers, namely, polyethylene glycol 6000 (PEG 6000 and polyvinyl pyrrolidone (PVP, were used as structure directing agents. The samples were characterized by X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, and scanning electron microscopy (SEM. The X-ray diffraction pattern revealed the formation of phase-pure ZnO micropowders. It is observed that the polymers play an important role in modifying the surface morphology and the size of the crystallites. A compact granular morphology is observed for the ZnO samples without polymer. The samples exhibit microparticles of size 100 nm for PVP and for PEG-mediated growth, whereas microporous corrugated morphology is observed for added PEG-mediated micropowder. FTIR study is used to confirm the structural modifications occurring in the polymers.

  8. Fluidization and Active Thinning by Molecular Kinetics in Active Gels.

    Science.gov (United States)

    Oriola, David; Alert, Ricard; Casademunt, Jaume

    2017-02-24

    We derive the constitutive equations of an active polar gel from a model for the dynamics of elastic molecules that link polar elements. Molecular binding kinetics induces the fluidization of the material, giving rise to Maxwell viscoelasticity and, provided that detailed balance is broken, to the generation of active stresses. We give explicit expressions for the transport coefficients of active gels in terms of molecular properties, including nonlinear contributions on the departure from equilibrium. In particular, when activity favors linker unbinding, we predict a decrease of viscosity with activity-active thinning-of kinetic origin, which could explain some experimental results on the cell cortex. By bridging the molecular and hydrodynamic scales, our results could help understand the interplay between molecular perturbations and the mechanics of cells and tissues.

  9. Study on the Ion Association in PVdF-based Gel Polymer Electrolyte

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Gel polymer electrolytes based on the poly (vinylidene fluoride) (PVdF) and the electrolyte of LiClO4 in propylene carbonate (PC) were prepared by the solution casting technique. The ionic conductivity of the gel electrolytes was concentration of lithium salt. Because of the strong coulombiq attractions, the dissolved salt ions might aggregate into ion pairs and multiple ion aggregates. The analysis of DSC and X-ray diffraction revealed that the ions association occurred at higher concentration of lithium salt.

  10. Electron Beam Dosimetry in Heterogeneous Phantoms Using a MAGIC Normoxic Polymer Gel

    Directory of Open Access Journals (Sweden)

    Ruhollah Ghahraman Asl

    2010-03-01

    Full Text Available Introduction: Nowadays radiosensitive polymer gels are used as a reliable dosimetry tool for verification of 3D dose distributions. Special characteristics of these dosimeters have made them useful for verification of complex dose distributions in clinical situations. The aim of this work was to evaluate the capability of a normoxic polymer gel to determine electron dose distributions in different slab phantoms in presence of small heterogeneities. Materials and Methods: Different cylindrical phantoms consisting gel were used under slab phantoms during each irradiation. MR images of irradiated gel phantoms were obtained to determine their R2 relaxation maps. 1D and 2D lateral dose profiles were acquired at depths of 1 cm for an 8 MeV beam and 1 and 4 cm for the 15 MeV energy, and then compared with the lateral dose profiles measured using a diode detector. In addition, 3D dose distributions around these heterogeneities for the same energies and depths were measured using a gel dosimeter. Results: Dose resolution for MR gel images at the range of 0-10 Gy was less than 1.55 Gy. Mean dose difference and distance to agreement (DTA for dose profiles were 2.6% and 2.2 mm, respectively. The results of the MAGIC-type polymer gel for bone heterogeneity at 8 MeV showed a reduction in dose of approximately 50%, and 30% and 10% at depths 1 and 4 cm at 15 MeV. However, for air heterogeneity increases in dose of approximately 50% at depth 1 cm under the heterogeneity at 8 MeV and 20% and 45% respectively at 15 MeV were observed. Discussion and Conclusion: Generally, electron beam distributions are significantly altered in the presence of tissue inhomogeneities such as bone and air cavities, this being related to mass stopping and mass scattering powers of heterogeneous materials. At the same time, hot and cold scatter lobes under heterogeneity regions due to scatter edge effects were also seen. However, these effects (increased dose, reduced dose, hot and

  11. Ionic conductivity and battery characteristic studies of a new PAN-based Na+ ion conducting gel polymer electrolyte system

    Science.gov (United States)

    Krishna Jyothi, N.; Vijaya Kumar, K.; Sunita Sundari, G.; Narayana Murthy, P.

    2016-03-01

    Sodium ion conducting gel polymer electrolytes based on polyacrylonitrile (PAN) with ethylene carbonate and dimethyl formamide as plasticizing solvents are prepared by the solution cast technique. These electrolyte films are free standing, transparent and dimensionally stable. Na+ ions are derived from NaI. The structural properties of pure and complex formations have been examined by X-ray diffraction, Fourier transform infrared spectroscopic studies and differential scanning calorimetric studies. The variation of the conductivity with salt concentration ranging from 10 to 40 wt% is studied. The sample containing 30 wt% of NaI exhibits the highest conductivity of 2.35 × 10-4 S cm-1 at room temperature (303 K) and 1 × 10-3 S cm-1 at 373 K. The conductivity-temperature dependence of polymer electrolyte films obeys Arrhenius behavior with activation energy in the range of 0.25-0.46 eV. The transport numbers both electronic ( t e) and ionic ( t i) are evaluated using Wagner's polarization technique. It is revealed that the conducting species are predominantly due to ions. The ionic transport number of highest conducting film is found to be 0.991. Solid-state battery with configuration Na/(PAN + NaI)/(I2 + C + electrolyte) is developed using the highest conducting gel polymer electrolyte system and the discharge characteristics of the cell are evaluated over the load of 100 KΩ.

  12. Development of a piezo-cantilever transducer and measuring method for evaluation of a temperature-sensitive polymer gel membrane

    Science.gov (United States)

    Li, Fenlan; Jiang, Zhongwei

    2007-06-01

    This paper is concerned with the development of a cantilever transducer patched with a piezoelectric element for evaluating the characteristics of a temperature-sensitive polymer gel membrane. The transducer consists of an aluminum cantilever beam patched with a piezoelectric ceramic and a probe coated by a polymer gel membrane. The probe can be easily attached to the cantilever transducer with double-sided sticky tape. The piezo-cantilever transducer is first simulated with the aid of a finite element method and the relation between the natural frequency change of the transducer and the absorbed mass on the polymer gel membrane is obtained theoretically. For measuring the temperature characteristics of the polymer gel membrane, the experiments are conducted in liquid and out of liquid. The temperature-sensitive poly(N-isopropylacrylamide) gel membrane hydrophilic-hydrophobic characteristics can be explained clearly by the results. Furthermore, two kinds of membrane coating method were proposed. The results indicate that the coating gel membrane has a better effect than the pasted gel membrane. The results also show that the piezo-cantilever transducer has a potential application for detecting polymer gel membrane characteristics conveniently and accurately.

  13. Lithium ion conductivity of gel polymer electrolytes containing insoluble lithium tetrakis(pentafluorobenzenethiolato) borate

    Energy Technology Data Exchange (ETDEWEB)

    Aoki, Takahiro; Ohta, Takayuki; Fujinami, Tatsuo [Department of Materials Science and Chemical Engineering, Faculty of Engineering, Shizuoka University, 3-5-1, Johoku, Hamamatsu 432-8561 (Japan)

    2006-06-01

    Lithium ion conducting gel polymer electrolytes composed of insoluble lithium tetrakis(pentafluorobenzenethiolato) borate (LiTPSB), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and ethylene carbonate-propylene carbonate mixed solvent (EC-PC) were prepared and their ionic conductivities and electrochemical stabilities were investigated. Ionic conductivity was largely dependent on the contents of EC-PC and LiTPSB. Gel polymer electrolyte containing optimized content of 50 (LiTPSB)-50 (PVDF-HFP/EC-PC (13:87wt.%)) exhibited ionic conductivity of 4x10{sup -4}Scm{sup -1} at 30{sup o}C, lithium ion transference number of 0.33 and anodic oxidation potential of 4.2V. (author)

  14. Lithium ion conductivity of gel polymer electrolytes containing insoluble lithium tetrakis(pentafluorobenzenethiolato) borate

    Science.gov (United States)

    Aoki, Takahiro; Ohta, Takayuki; Fujinami, Tatsuo

    Lithium ion conducting gel polymer electrolytes composed of insoluble lithium tetrakis(pentafluorobenzenethiolato) borate (LiTPSB), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and ethylene carbonate-propylene carbonate mixed solvent (EC-PC) were prepared and their ionic conductivities and electrochemical stabilities were investigated. Ionic conductivity was largely dependent on the contents of EC-PC and LiTPSB. Gel polymer electrolyte containing optimized content of 50 (LiTPSB)-50 (PVDF-HFP/EC-PC (13:87 wt.%)) exhibited ionic conductivity of 4 × 10 -4 S cm -1 at 30 °C, lithium ion transference number of 0.33 and anodic oxidation potential of 4.2 V.

  15. Li Ion Conducting Polymer Gel Electrolytes Based on Ionic Liquid/PVDF-HFP Blends.

    Science.gov (United States)

    Ye, Hui; Huang, Jian; Xu, Jun John; Khalfan, Amish; Greenbaum, Steve G

    2007-09-21

    Ionic liquids thermodynamically compatible with Li metal are very promising for applications to rechargeable lithium batteries. 1-methyl-3-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P(13)TFSI) is screened out as a particularly promising ionic liquid in this study. Dimensionally stable, elastic, flexible, nonvolatile polymer gel electrolytes (PGEs) with high electrochemical stabilities, high ionic conductivities and other desirable properties have been synthesized by dissolving Li imide salt (LiTFSI) in P(13)TFSI ionic liquid and then mixing the electrolyte solution with poly(vinylidene-co-hexafluoropropylene) (PVDF-HFP) copolymer. Adding small amounts of ethylene carbonate to the polymer gel electrolytes dramatically improves the ionic conductivity, net Li ion transport concentration, and Li ion transport kinetics of these electrolytes. They are thus favorable and offer good prospects in the application to rechargeable Li batteries including open systems like Li/air batteries, as well as more "conventional" rechargeable lithium and lithium ion batteries.

  16. Li Ion Conducting Polymer Gel Electrolytes Based on Ionic Liquid/PVDF-HFP Blends

    Science.gov (United States)

    Ye, Hui; Huang, Jian; Xu, Jun John; Khalfan, Amish; Greenbaum, Steve G.

    2009-01-01

    Ionic liquids thermodynamically compatible with Li metal are very promising for applications to rechargeable lithium batteries. 1-methyl-3-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P13TFSI) is screened out as a particularly promising ionic liquid in this study. Dimensionally stable, elastic, flexible, nonvolatile polymer gel electrolytes (PGEs) with high electrochemical stabilities, high ionic conductivities and other desirable properties have been synthesized by dissolving Li imide salt (LiTFSI) in P13TFSI ionic liquid and then mixing the electrolyte solution with poly(vinylidene-co-hexafluoropropylene) (PVDF-HFP) copolymer. Adding small amounts of ethylene carbonate to the polymer gel electrolytes dramatically improves the ionic conductivity, net Li ion transport concentration, and Li ion transport kinetics of these electrolytes. They are thus favorable and offer good prospects in the application to rechargeable Li batteries including open systems like Li/air batteries, as well as more “conventional” rechargeable lithium and lithium ion batteries. PMID:20354587

  17. Active Polymers Confer Fast Reorganization Kinetics

    CERN Document Server

    Swanson, Douglas

    2011-01-01

    Many cytoskeletal biopolymers are "active," consuming energy in large quantities. In this Letter, we identify a fundamental difference between active polymers and passive, equilibrium polymers: for equal mean lengths, active polymers can reorganize faster than equilibrium polymers. We show that equilibrium polymers are intrinsically limited to linear scaling between mean lifetime and mean length, MFPT ~ , by analogy to 1-d Potts models. By contrast, we present a simple active-polymer model that improves upon this scaling, such that MFPT ~ ^{1/2}. Since to be biologically useful, structural biopolymers must typically be many monomers long, yet respond dynamically to the needs of the cell, the difference in reorganization kinetics may help to justify active polymers' greater energy cost. PACS numbers: 87.10.Ed, 87.16.ad, 87.16.Ln

  18. Li Ion Conducting Polymer Gel Electrolytes Based on Ionic Liquid/PVDF-HFP Blends

    OpenAIRE

    Ye, Hui; Huang, Jian; Xu, Jun John; Khalfan, Amish; Greenbaum, Steve G.

    2007-01-01

    Ionic liquids thermodynamically compatible with Li metal are very promising for applications to rechargeable lithium batteries. 1-methyl-3-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P13TFSI) is screened out as a particularly promising ionic liquid in this study. Dimensionally stable, elastic, flexible, nonvolatile polymer gel electrolytes (PGEs) with high electrochemical stabilities, high ionic conductivities and other desirable properties have been synthesized by dissolving Li i...

  19. TiO2–Polymer Nano–Composites by Sol–Gel

    OpenAIRE

    A. C. Pierre; Campet, G.; Han, S.D.; Huang, S.Y.; E. DUGUET; Portier, J.

    1995-01-01

    Sol-gel processes make it possible to develop new hybrid electrolyte materials of the type ceramic-polymer, known as Nano-Crystallite-Insertion-Material (NCIM). They can be used in reversible alkali electrochemical cells after insertion with cations such as Li+. In the present study, TiO2-polyethylene oxide hybrid materials were synthesized from TiCl4 and from Ti ethoxide. Their structure is analyzed in relation with the processing parameters. A primary evaluation of the nanoscale co...

  20. Ordered zigzag stripes of polymer gel/metal nanoparticle composites for highly stretchable conductive electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Hyun, Dong Choon; Park, Minwoo; Park, ChooJin; Kim, Bongsoo; Jeong, Unyong [Department of Materials Science and Engineering, Yonsei University, 134 Shinchon-dong, Seoul (Korea, Republic of); Xia, Younan [Department of Materials Science and Engineering, Yonsei University, 134 Shinchon-dong, Seoul (Korea, Republic of); Department of Biomedical Engineering, Washington University, St. Louis, MO 63130 (United States); Hur, Jae Hyun; Kim, Jong Min; Park, Jong Jin [Samsung Advanced Institute of Technology, Mt.14-1, Nongseo-Dong, Giheung-Gu, Yongin-Si, Gyeonggi-Do 446-712 (Korea, Republic of)

    2011-07-12

    Highly stretchable conductive composite lines with an ordered zigzag structure are prepared. The high stretchability arises from the interpenetrating network between the polymer gel and Ag nanoparticles, as well as the ordered zigzag morphology. Double transfer of the structures in a perpendicular configuration allows for the fabrication of 2D stretchable electrodes. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Effect of polymer aggregation on the open circuit voltage in organic photovoltaic cells: aggregation-induced conjugated polymer gel and its application for preventing open circuit voltage drop.

    Science.gov (United States)

    Kim, Bong-Gi; Jeong, Eun Jeong; Park, Hui Joon; Bilby, David; Guo, L Jay; Kim, Jinsang

    2011-03-01

    To investigate the structure-dependent aggregation behavior of conjugated polymers and the effect of aggregation on the device performance of conjugated polymer photovoltaic cells, new conjugated polymers (PVTT and CN-PVTT) having the same regioregularity but different intermolecular packing were prepared and characterized by means of UV-vis spectroscopy and atomic force microscopy (AFM). Photovoltaic devices were prepared with these polymers under different polymer-aggregate conditions. Polymer aggregation induced by thermal annealing increases the short circuit current but provides no advantage in the overall power conversion efficiency because of a decrease in the open circuit voltage. The device fabricated from a pre-aggregated polymer suspension, acquired from ultrasonic agitation of a conjugated polymer gel, showed enhanced performance because of better phase separation and reduced recombination between polymer/PCBM.

  2. An x-ray CT polymer gel dosimetry prototype: I. Remnant artefact removal.

    Science.gov (United States)

    Jirasek, A; Carrick, J; Hilts, M

    2012-05-21

    In this study a new x-ray CT polymer gel dosimetry (PGD) filtering technique is presented for the removal of (i) remnant ring and streak artefacts, and (ii) 'structured' noise in the form of minute, intrinsic gel density fluctuations. It is shown that the noise present within x-ray CT PGD images is not purely stochastic (pixel by pixel) in nature, but rather is 'structured', and hence purely stochastic-based noise-removal filters fail in removing this significant, unwanted noise component. The remnant artefact removal (RAR) technique is based on a class of signal stripping (i.e. baseline-estimation) algorithms typically used in the estimation of unwanted non-uniform baselines underlying spectral data. Here the traditional signal removal algorithm is recast, whereby the 'signal' that is removed is the structured noise and remnant artefacts, leaving the desired polymer gel dose distribution. The algorithm is extended to 2D and input parameters are optimized for PGD images. RAR filter results are tested on (i) synthetic images with measured gel background images added, in order to accurately represent actual noise present in PGD images, and (ii) PGD images of a three-field gel irradiation. RAR results are compared to a top-performing noise filter (adaptive mean, AM), used in previous x-ray CT PGD studies. It is shown that, in all cases, the RAR filter outperforms the AM filter, particularly in cases where either (i) a low-dose gel image has been acquired or (ii) the signal-to-noise ratio of the PG image is low, as in the case when a low number of image averages are acquired within a given experiment. Guidelines for the implementation of the RAR filter are given.

  3. Development of Polymer Gel Systems to Improve Volumetric Sweep and Reduce Producing Water/Oil Ratios

    Energy Technology Data Exchange (ETDEWEB)

    G. Paul Willhite; Stan McCool; Don W. Green; Min Cheng; Feiyan Chen

    2005-12-31

    Gelled polymer treatments are applied to oil reservoirs to increase oil production and to reduce water production by altering the fluid movement within the reservoir. This report describes the results of a 42-month research program that focused on the understanding of gelation chemistry and the fundamental mechanisms that alter the flows of oil and water in reservoir rocks after a gel treatment. Work was conducted on a widely applied system in the field, the partially hydrolyzed polyacrylamide-chromium acetate gel. Gelation occurs by network formation through the crosslinking of polyacrylamide molecules as a result of reaction with chromium acetate. Pre-gel aggregates form and grow as reactions between chromium acetate and polyacrylamide proceed. A rate equation that describes the reaction between chromium acetate and polymer molecules was regressed from experimental data. A mathematical model that describes the crosslinking reaction between two polymer molecules as a function of time was derived. The model was based on probability concepts and provides molecular-weight averages and molecular-weight distributions of the pre-gel aggregates as a function of time and initial system conditions. Average molecular weights of pre-gel aggregates were measured as a function of time and were comparable to model simulations. Experimental methods to determine molecular weight distributions of pre-gel aggregates were unsuccessful. Dissolution of carbonate minerals during the injection of gelants causes the pH of the gelant to increase. Chromium precipitates from solution at the higher pH values robbing the gelant of crosslinker. Experimental data on the transport of chromium acetate solutions through dolomite cores were obtained. A mathematical model that describes the transport of brine and chromium acetate solutions through rocks containing carbonate minerals was used to simulate the experimental results and data from literature. Gel treatments usually reduce the permeability

  4. Thiourea incorporated poly(ethylene oxide) as transparent gel polymer electrolyte for dye sensitized solar cell applications

    Science.gov (United States)

    Pavithra, Nagaraj; Velayutham, David; Sorrentino, Andrea; Anandan, Sambandam

    2017-06-01

    A new series of transparent gel polymer electrolytes are prepared by adding various weight percent of thiourea coupled with poly(ethylene oxide) for the application of dye-sensitized solar cells. Coupling of thiourea in the presence of iodine undergoes dimerization reaction to produce formamidine disulfide. Fourier Transform Infrared spectroscopy shows that the interactions of thiourea and formamidine disulfide with electronegative ether linkage of poly(ethylene oxide) results in conformational changes of gel polymer electrolytes. Electrochemical impedance spectroscopy and linear sweep voltammetry experiments reveal an increment in ionic conductivity and tri-iodide diffusion coefficient, for thiourea modified gel polymer electrolytes. Finally, the prepared electrolytes are used as a redox mediator in dye-sensitized solar cells and the photovoltaic properties were studied. Apart from transparency, the gel polymer electrolytes with thiorurea show higher photovoltaic properties compared to bare gel polymer electrolyte and a maximum photocurrent efficiency of 7.17% is achieved for gel polymer electrolyte containing 1 wt% of thiourea with a short circuit current of 11.79 mA cm-2 and open circuit voltage of 834 mV. Finally, under rear illumination, almost 90% efficiency is retained upon compared to front illumination.

  5. Thermal stability, complexing behavior, and ionic transport of polymeric gel membranes based on polymer PVdF-HFP and ionic liquid, [BMIM][BF4].

    Science.gov (United States)

    Shalu; Chaurasia, S K; Singh, R K; Chandra, S

    2013-01-24

    PVdF-HFP + IL(1-butyl-3-methylimidazolium tetrafluoroborate; [BMIM][BF(4)]) polymeric gel membranes containing different amounts of ionic liquid have been synthesized and characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared (FTIR), differential scanning calorimetry, thermogravimetric analysis (TGA), and complex impedance spectroscopic techniques. Incorporation of IL in PVdF-HFP polymer changes different physicochemical properties such as melting temperature (T(m)), thermal stability, structural morphology, amorphicity, and ionic transport. It is shown by FTIR, TGA (also first derivative of TGA, "DTGA") that IL partly complexes with the polymer PVdF-HFP and partly remains dispersed in the matrix. The ionic conductivity of polymeric gel membranes has been found to increase with increasing concentration of IL and attains a maximum value of 1.6 × 10(-2) S·cm(-1) for polymer gel membrane containing 90 wt % IL at room temperature. Interestingly, the values of conductivity of membranes with 80 and 90 wt % of IL were higher than that of pure IL (100 wt %). The polymer chain breathing model has been suggested to explain it. The variation of ionic conductivity with temperature of these gel polymeric membranes follows Arrhenius type thermally activated behavior.

  6. Nanostructured Conductive Polymer Gels as a General Framework Material To Improve Electrochemical Performance of Cathode Materials in Li-Ion Batteries.

    Science.gov (United States)

    Shi, Ye; Zhou, Xingyi; Zhang, Jun; Bruck, Andrea M; Bond, Andrew C; Marschilok, Amy C; Takeuchi, Kenneth J; Takeuchi, Esther S; Yu, Guihua

    2017-03-08

    Controlling architecture of electrode composites is of particular importance to optimize both electronic and ionic conduction within the entire electrode and improve the dispersion of active particles, thus achieving the best energy delivery from a battery. Electrodes based on conventional binder systems that consist of carbon additives and nonconductive binder polymers suffer from aggregation of particles and poor physical connections, leading to decreased effective electronic and ionic conductivities. Here we developed a three-dimensional (3D) nanostructured hybrid inorganic-gel framework electrode by in situ polymerization of conductive polymer gel onto commercial lithium iron phosphate particles. This framework electrode exhibits greatly improved rate and cyclic performance because the highly conductive and hierarchically porous network of the hybrid gel framework promotes both electronic and ionic transport. In addition, both inorganic and organic components are uniformly distributed within the electrode because the polymer coating prevents active particles from aggregation, enabling full access to each particle. The robust framework further provides mechanical strength to support active electrode materials and improves the long-term electrochemical stability. The multifunctional conductive gel framework can be generalized for other high-capacity inorganic electrode materials to enable high-performance lithium ion batteries.

  7. Preconcentration and Determination of Mefenamic Acid in Pharmaceutical and Biological Fluid Samples by Polymer-grafted Silica Gel Solid-phase Extraction Following High Performance Liquid Chromatography

    Science.gov (United States)

    Bagheri Sadeghi, Hayedeh; Panahi, Homayon Ahmad; Mahabadi, Mahsa; Moniri, Elham

    2015-01-01

    Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) that has analgesic, anti-infammatory and antipyretic actions. It is used to relieve mild to moderate pains. Solid-phase extraction of mefenamic acid by a polymer grafted to silica gel is reported. Poly allyl glycidyl ether/iminodiacetic acid-co-N, N-dimethylacrylamide was synthesized and grafted to silica gel and was used as an adsorbent for extraction of trace mefenamic acid in pharmaceutical and biological samples. Different factors affecting the extraction method were investigated and optimum conditions were obtained. The optimum pH value for sorption of mefenamic acid was 4.0. The sorption capacity of grafted adsorbent was 7.0 mg/g. The best eluent solvent was found to be trifluoroacetic acid-acetic acid in methanol with a recovery of 99.6%. The equilibrium adsorption data of mefenamic acid by grafted silica gel was analyzed by Langmuir model. The conformation of obtained data to Langmuir isotherm model reveals the homogeneous binding sites of grafted silica gel surface. Kinetic study of the mefenamic acid sorption by grafted silica gel indicates the good accessibility of the active sites in the grafted polymer. The sorption rate of the investigated mefenamic acid on the grafted silica gel was less than 5 min. This novel synthesized adsorbent can be successfully applied for the extraction of trace mefenamic acid in human plasma, urine and pharmaceutical samples. PMID:26330865

  8. FORMULATION AND EVALUATION OF POLYHERBAL GEL FOR ANTI - INFLAMMATORY ACTIVITY

    Directory of Open Access Journals (Sweden)

    Gouri Dixit*, Ganesh Misal, Vijay Gulkari and Kanchan Upadhye

    2013-03-01

    Full Text Available ABSTRACT: In the present study, three medicinal plants Cynodon dactylon (L. Pers, Cassia tora Linn. and Cassia alata Linn having significant anti-inflammatory potential were selected to be formulated as polyherbal gels. The gels were prepared using the dried methanolic extract of Cassia tora Linn, Cassia alata Linn and Cynodon dactylon (L. Pers. Polyherbal gel formulations were evaluated for its pH, appearance and homogeneity, viscosity, spreadability and skin irritation studies. Assessment of Anti-inflammatory activity was done by carrageenan induced rat paw edema and formalin- induced rat paw edema. Individual and polyherbal gel of Cassia alata Linn,Cassia tora Linn. and Cynodon dactylon (L. Pers were found to possess anti-inflammatory effect in acute and chronic models. Polyherbal gel also showed synergistic effect as compared to individual gels which can be useful for the treatment of local inflammation.

  9. Structure and Hydrogen Bonding of Water in Polyacrylate Gels: Effects of Polymer Hydrophilicity and Water Concentration.

    Science.gov (United States)

    Mani, Sriramvignesh; Khabaz, Fardin; Godbole, Rutvik V; Hedden, Ronald C; Khare, Rajesh

    2015-12-10

    The ability to tune the hydrophilicity of polyacrylate copolymers by altering their composition makes these materials attractive candidates for membranes used to separate alcohol-water mixtures. The separation behavior of these polyacrylate membranes is governed by a complex interplay of factors such as water and alcohol concentrations, water structure in the membrane, polymer hydrophilicity, and temperature. We use molecular dynamics simulations to investigate the effect of polymer hydrophilicity and water concentration on the structure and dynamics of water molecules in the polymer matrix. Samples of poly(n-butyl acrylate) (PBA), poly(2-hydroxyethyl acrylate) (PHEA), and a 50/50 copolymer of BA and HEA were synthesized in laboratory, and their properties were measured. Model structures of these systems were validated by comparing the simulated values of their volumetric properties with the experimental values. Molecular simulations of polyacrylate gels swollen in water and ethanol mixtures showed that water exhibits very different affinities toward the different (carbonyl, alkoxy, and hydroxyl) functional groups of the polymers. Water molecules are well dispersed in the system at low concentrations and predominantly form hydrogen bonds with the polymer. However, water forms large clusters at high concentrations along with the predominant formation of water-water hydrogen bonds and the acceleration of hydrogen bond dynamics.

  10. Chaotic behavior of ion exchange phenomena in polymer gel electrolytes through irradiated polymeric membrane

    Energy Technology Data Exchange (ETDEWEB)

    Rawat, Sangeeta; Saha, Barnamala; Prasad, Awadhesh [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Chandra, Amita, E-mail: achandra@physics.du.ac.in [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)

    2012-05-14

    A desktop experiment has been done to show the nonlinearity in the I–V characteristics of an ion conducting electrochemical micro-system. Its chaotic dynamics is being reported for the first time which has been captured by an electronic circuit. Polyvinylidene fluoride-co-hexafluoropropene (PVdF-HFP) gel electrolyte comprising of a combination of plasticizers (ethylene carbonate and propylene carbonate) and salts have been prepared to study the exchange of ions through porous polyethylene terephthalate (PET) membranes. The nonlinearity of this system is due to the ion exchange of the polymer gel electrolytes (PGEs) through a porous membrane. The different regimes of spiking and non-spiking chaotic motions are being presented. The possible applications are highlighted. -- Highlights: ► For the first time, the nonlinear dynamics of an electrochemical micro-system has been reported. ► The nonlinearity generates due to the ion exchange of polymer gel electrolytes through irradiated polymeric membrane. ► The nonlinearity can be tailored by changing the pore size of irradiated membrane. ► Sprott's circuit has been modified to capture the phenomena of ion transport through membrane. ► Attractor formation and Lyapunov exponent confirms the chaotic behavior of presently investigated system.

  11. Self-assembling semiconducting polymers--rods and gels from electronic materials.

    Science.gov (United States)

    Clark, Andrew P-Z; Shi, Chenjun; Ng, Benny C; Wilking, James N; Ayzner, Alexander L; Stieg, Adam Z; Schwartz, Benjamin J; Mason, Thomas G; Rubin, Yves; Tolbert, Sarah H

    2013-02-26

    In an effort to favor the formation of straight polymer chains without crystalline grain boundaries, we have synthesized an amphiphilic conjugated polyelectrolyte, poly(fluorene-alt-thiophene) (PFT), which self-assembles in aqueous solutions to form cylindrical micelles. In contrast to many diblock copolymer assemblies, the semiconducting backbone runs parallel, not perpendicular, to the long axis of the cylindrical micelle. Solution-phase micelle formation is observed by X-ray and visible light scattering. The micelles can be cast as thin films, and the cylindrical morphology is preserved in the solid state. The effects of self-assembly are also observed through spectral shifts in optical absorption and photoluminescence. Solutions of higher-molecular-weight PFT micelles form gel networks at sufficiently high aqueous concentrations. Rheological characterization of the PFT gels reveals solid-like behavior and strain hardening below the yield point, properties similar to those found in entangled gels formed from surfactant-based micelles. Finally, electrical measurements on diode test structures indicate that, despite a complete lack of crystallinity in these self-assembled polymers, they effectively conduct electricity.

  12. Experimental investigations of an ionic-liquid-based, magnesium ion conducting, polymer gel electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, G.P.; Hashmi, S.A. [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)

    2009-02-15

    Studies on a novel magnesium ion conducting gel polymer electrolyte based on a room temperature ionic liquid (RTIL) is reported. It comprises a Mg-salt, Mg(CF{sub 3}SO{sub 3}){sub 2} [or magnesium triflate, Mg(Tf){sub 2}] solution in an ionic liquid, 1-ethyl-3-methylimidazolium trifluoro-methanesulfonate (EMITf), immobilized with poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP), which is a freestanding, semitransparent and flexible film with excellent mechanical strength. Physical and electrochemical analyses demonstrate promising characteristics of these films, suitable as electrolytes in rechargeable magnesium batteries. The material offers a maximum electrical conductivity of {proportional_to}4.8 x 10{sup -3} S cm{sup -1} at room temperature (20 C) with excellent thermal and electrochemical stabilities. Possible conformational changes in the polymer host PVdF-HFP due to ionic liquid solution entrapment and ion-polymer interaction are investigated by Fourier transform infra-red (FTIR), X-ray diffraction (XRD) and scanning electron microscopic (SEM) methods. The Mg{sup 2+} ion transport in the gel film is confirmed from cyclic voltammetry, impedance and transport number measurements. The Mg{sup 2+} ion transport number (t{sub +}) is {proportional_to}0.26, which indicates a substantial contribution of triflate anion transport along with ionic conduction due to the component ions of the ionic liquid. (author)

  13. Magnesium ion-conducting gel polymer electrolytes dispersed with nanosized magnesium oxide

    Science.gov (United States)

    Pandey, G. P.; Agrawal, R. C.; Hashmi, S. A.

    Experimental investigations are performed on novel magnesium ion-conducting gel polymer electrolyte nanocomposites based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP), dispersed with nanosized magnesium oxide (MgO) particles. The nanocomposite materials are in the form of free-standing films. Various physical and electrochemical analyses demonstrate promising characteristics of these films, suitable as electrolytes in rechargeable magnesium batteries. The optimized material with 3 wt.% MgO offers a maximum electrical conductivity of ∼8 × 10 -3 S cm -1 at room temperature (∼25 °C) with good thermal and electrochemical stabilities. The ion/filler-polymer interactions and possible conformational changes in host polymer PVdF-HFP due to the liquid electrolyte entrapment and dispersion of nanosized MgO are examined by Fourier transform infrared (FTIR), X-ray diffraction (XRD) and scanning electron microscopic (SEM) methods. The Mg 2+ ion conduction in the gel film is confirmed from the cyclic voltammetry, impedance spectroscopy and transport number measurements. The Mg 2+ ion transport number (t +) is enhanced substantially and found to have a maximum of ∼0.44 for the addition of 10 wt.% MgO nanoparticles. The enhancement in t + is explained on the basis of the formation of space-charge regions due to the presence of MgO:Mg 2+-like species, that supports Mg 2+ ion motion.

  14. Experimental investigations of an ionic-liquid-based, magnesium ion conducting, polymer gel electrolyte

    Science.gov (United States)

    Pandey, G. P.; Hashmi, S. A.

    Studies on a novel magnesium ion conducting gel polymer electrolyte based on a room temperature ionic liquid (RTIL) is reported. It comprises a Mg-salt, Mg(CF 3SO 3) 2 [or magnesium triflate, Mg(Tf) 2] solution in an ionic liquid, 1-ethyl-3-methylimidazolium trifluoro-methanesulfonate (EMITf), immobilized with poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP), which is a freestanding, semitransparent and flexible film with excellent mechanical strength. Physical and electrochemical analyses demonstrate promising characteristics of these films, suitable as electrolytes in rechargeable magnesium batteries. The material offers a maximum electrical conductivity of ∼4.8 × 10 -3 S cm -1 at room temperature (20 °C) with excellent thermal and electrochemical stabilities. Possible conformational changes in the polymer host PVdF-HFP due to ionic liquid solution entrapment and ion-polymer interaction are investigated by Fourier transform infra-red (FTIR), X-ray diffraction (XRD) and scanning electron microscopic (SEM) methods. The Mg 2+ ion transport in the gel film is confirmed from cyclic voltammetry, impedance and transport number measurements. The Mg 2+ ion transport number (t +) is ∼0.26, which indicates a substantial contribution of triflate anion transport along with ionic conduction due to the component ions of the ionic liquid.

  15. Electrical and electrochemical studies on sodium ion-based gel polymer electrolytes

    Science.gov (United States)

    Isa, K. B. Md; Othman, L.; Hambali, D.; Osman, Z.

    2017-09-01

    Gel polymer electrolytes (GPEs) have captured great attention because of their unique properties such as good mechanical stability, high flexibility and high conductivity approachable to that of the liquid electrolytes. In this work, we have prepared sodium ion conducting gel polymer electrolyte (GPE) films consisting of polyvinylidenefluoride-co-hexafluoropropylene (PVdF-HFP) as a polymer host using the solution casting technique. Sodium trifluoromethane- sulfonate (NaCF3SO3) was used as an ionic salt and the mixture of ethylene carbonate (EC) and propylene carbonate (PC) as a plasticizing solvent. Impedance spectroscopy measurements were carried out to determine the ionic conductivity of the GPE films. The sample containing 20 wt.% of NaCF3SO3 salt exhibits the highest room temperature ionic conductivity of 2.50 × 10-3 S cm-1. The conductivity of the GPE films was found to depend on the salt concentration that added to the films. The ionic and cationic transference numbers of GPE films were estimated by DC polarization and the combination of AC and DC polarization method, respectively. The results had shown that both ionic and cationic transference numbers are consistent with the conductivity studies. The electrochemical stability of the GPE films was tested using linear sweep voltammetry (LSV) and the value of working voltage range appears to be high enough to be used as an electrolyte in sodium batteries. The cyclic voltammetry (CV) studies confirmed the sodium ion conduction in the GPE films.

  16. Theory of DNA electrophoresis in physical gels and entangled polymer solutions

    Science.gov (United States)

    Duke, Thomas; Viovy, Jean Louis

    1994-03-01

    A scaling theory is presented for the electrophoretic mobility of DNA in sieving media that form dynamically evolving meshworks, such as physical gels and solutions of entangled polymers. In such media, the topological constraints on the DNA's motion are perpetually changing as cross links break and rejoin or as the polymers diffuse. It is shown that if the rate of constraint release falls within a certain range (which depends on the field strength), fractionation can be extended to higher molecular weights than would be feasible using a permanent gel of equivalent pore size. This improvement is a consequence of the disruptive effect that constraint release has on the mechanism of molecular orientation. Numerical simulations support the predictions of the theory. The possibility of realizing such a system in practice, with the aim of improving on current electrophoresis methods, is commented upon. It is suggested that semidilute polymer solutions may be a versatile medium for the rapid separation of long single-stranded DNA molecules, and the particular quality of solution required is identified.

  17. Blade-coated sol-gel indium-gallium-zinc-oxide for inverted polymer solar cell

    Directory of Open Access Journals (Sweden)

    Yan-Huei Lee

    2016-11-01

    Full Text Available The inverted organic solar cell was fabricated by using sol-gel indium-gallium-zinc-oxide (IGZO as the electron-transport layer. The IGZO precursor solution was deposited by blade coating with simultaneous substrate heating at 120 °C from the bottom and hot wind from above. Uniform IGZO film of around 30 nm was formed after annealing at 400 °C. Using the blend of low band-gap polymer poly[(4,8-bis-(2-ethylhexyloxy-benzo(1,2-b:4,5-b’dithiophene-2,6-diyl-alt- (4-(2-ethylhexanoyl-thieno [3,4-b]thiophene--2-6-diyl] (PBDTTT-C-T and [6,6]-Phenyl C71 butyric acid methyl ester ([70]PCBM as the active layer for the inverted organic solar cell, an efficiency of 6.2% was achieved with a blade speed of 180 mm/s for the IGZO. The efficiency of the inverted organic solar cells was found to depend on the coating speed of the IGZO films, which was attributed to the change in the concentration of surface OH groups. Compared to organic solar cells of conventional structure using PBDTTT-C-T: [70]PCBM as active layer, the inverted organic solar cells showed significant improvement in thermal stability. In addition, the chemical composition, as well as the work function of the IGZO film at the surface and inside can be tuned by the blade speed, which may find applications in other areas like thin-film transistors.

  18. Blade-coated sol-gel indium-gallium-zinc-oxide for inverted polymer solar cell

    Science.gov (United States)

    Lee, Yan-Huei; Tsai, Pei-Ting; Chang, Chia-Ju; Meng, Hsin-Fei; Horng, Sheng-Fu; Zan, Hsiao-Wen; Lin, Hung-Cheng; Liu, Hung-Chuan; Tseng, Mei-Rurng; Yeh, Han-Cheng

    2016-11-01

    The inverted organic solar cell was fabricated by using sol-gel indium-gallium-zinc-oxide (IGZO) as the electron-transport layer. The IGZO precursor solution was deposited by blade coating with simultaneous substrate heating at 120 °C from the bottom and hot wind from above. Uniform IGZO film of around 30 nm was formed after annealing at 400 °C. Using the blend of low band-gap polymer poly[(4,8-bis-(2-ethylhexyloxy)-benzo(1,2-b:4,5-b')dithiophene)-2,6-diyl-alt- (4-(2-ethylhexanoyl)-thieno [3,4-b]thiophene-)-2-6-diyl)] (PBDTTT-C-T) and [6,6]-Phenyl C71 butyric acid methyl ester ([70]PCBM) as the active layer for the inverted organic solar cell, an efficiency of 6.2% was achieved with a blade speed of 180 mm/s for the IGZO. The efficiency of the inverted organic solar cells was found to depend on the coating speed of the IGZO films, which was attributed to the change in the concentration of surface OH groups. Compared to organic solar cells of conventional structure using PBDTTT-C-T: [70]PCBM as active layer, the inverted organic solar cells showed significant improvement in thermal stability. In addition, the chemical composition, as well as the work function of the IGZO film at the surface and inside can be tuned by the blade speed, which may find applications in other areas like thin-film transistors.

  19. Mesoporous sol-gel silica cladding for hybrid TiO2/electro-optic polymer waveguide modulators.

    Science.gov (United States)

    Enami, Yasufumi; Kayaba, Yasuhisa; Luo, Jingdong; Jen, Alex K-Y

    2014-06-30

    We report the efficient poling of an electro-optic (EO) polymer in a hybrid TiO(2)/electro-optic polymer multilayer waveguide modulator on mesoporous sol-gel silica cladding. The mesoporous sol-gel silica has nanometer-sized pores and a low refractive index of 1.24, which improves mode confinement in the 400-nm-thick EO polymer film in the modulators and prevents optical absorption from the lower Au electrode, thereby resulting in a lower half-wave voltage of the modulators. The half-wave voltage (Vπ) of the hybrid modulator fabricated on the mesoporous sol-gel silica cladding is 6.0 V for an electrode length (Le) of 5 mm at a wavelength of 1550 nm (VπLe product of 3.0 V·cm) using a low-index guest-host EO polymer (in-device EO coefficient of 75 pm/V).

  20. Insulin release from islets of Langerhans entrapped in a poly(N-isopropylacrylamide-co-acrylic acid) polymer gel.

    Science.gov (United States)

    Vernon, B; Kim, S W; Bae, Y H

    1999-01-01

    A copolymer of N-isopropylacrylamide (98 mol% in feed) and acrylic acid, poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAAm-co-AAc)), was prepared by free radical polymerization for development of a thermally reversible polymer to entrap islets of Langerhans for a refillable biohybrid artificial pancreas. A 5 wt% solution of the polymer in Hanks' balanced salt solution forms a gel at 37 degrees C that exhibits no syneresis. Diffusion of fluorescein isothiocyanate (FITC) dextrans having molecular weights of 4400 and 70000 were used to evaluate mass transport in the gel at 37 degrees C. Insulin secretion from islets in the polymer gel was also investigated in both static and dynamic systems. The polymer gel exhibited excellent diffusion of FITC dextran 4400 and FITC dextran 70000 with diffusion ratios, D/D0 (ratio of diffusion in the gel to diffusion in water), of 0.20+/-0.04 and 0.35+/-0.17, respectively. Human islets entrapped in the polymer gel showed prolonged insulin secretion in response to basal (5.5 mM) glucose concentration compared to free human islets. Rat islets showed prolonged insulin secretion in response to high (16.5 mM) glucose concentrations compared to free rat islets. Rat islets in the polymer gel maintained insulin secretion in response to the higher glucose concentration for over 26 days. Rat islets entrapped by the polymer also released higher quantities of insulin more rapidly in response to changes in concentrations of glucose and other stimulants than rat islets entrapped in an alginate control. These results suggest that this material would provide adequate diffusion for rapid insulin release in an application as a synthetic extracellular matrix for a biohybrid artificial pancreas.

  1. A circular polymer chain in a gel - the reduction of the state space

    CERN Document Server

    Krawczyk, Malgorzata J

    2012-01-01

    The state space of a polymer molecule is analysed. We show how the size of the state space can be reduced on the basis of symmetry. In the reduced state space, the probability of a new state (termed below as class) is equal to the number of old states represented by the new state multiplied by the probability of each old state. As an application, the electrophoretic motion of the molecule in gel is considered. We discuss the influence of the gel medium and of external field on the molecule states, with absorbing states of hooked molecules playing a major role. We show that in the case of strong fields both the velocity and the diffusion coefficient decrease with field. Finally, we evaluate the time of relaxation to and from the absorbing states. This is done with a continuous version of the exact enumeration method for weighted networks.

  2. Small field dose delivery evaluations using cone beam optical computed tomography-based polymer gel dosimetry

    Directory of Open Access Journals (Sweden)

    Timothy Olding

    2011-01-01

    Full Text Available This paper explores the combination of cone beam optical computed tomography with an N-isopropylacrylamide (NIPAM-based polymer gel dosimeter for three-dimensional dose imaging of small field deliveries. Initial investigations indicate that cone beam optical imaging of polymer gels is complicated by scattered stray light perturbation. This can lead to significant dosimetry failures in comparison to dose readout by magnetic resonance imaging (MRI. For example, only 60% of the voxels from an optical CT dose readout of a 1 l dosimeter passed a two-dimensional Low′s gamma test (at a 3%, 3 mm criteria, relative to a treatment plan for a well-characterized pencil beam delivery. When the same dosimeter was probed by MRI, a 93% pass rate was observed. The optical dose measurement was improved after modifications to the dosimeter preparation, matching its performance with the imaging capabilities of the scanner. With the new dosimeter preparation, 99.7% of the optical CT voxels passed a Low′s gamma test at the 3%, 3 mm criteria and 92.7% at a 2%, 2 mm criteria. The fitted interjar dose responses of a small sample set of modified dosimeters prepared (a from the same gel batch and (b from different gel batches prepared on the same day were found to be in agreement to within 3.6% and 3.8%, respectively, over the full dose range. Without drawing any statistical conclusions, this experiment gives a preliminary indication that intrabatch or interbatch NIPAM dosimeters prepared on the same day should be suitable for dose sensitivity calibration.

  3. Determine the Dose Distribution Using Ultrasound Parameters in MAGIC-f Polymer Gels

    Directory of Open Access Journals (Sweden)

    Hossein Masoumi

    2016-02-01

    Full Text Available In this study, using methacrylic and ascorbic acid in gelatin initiated by copper (MAGIC-f polymer gel after megavoltage energy exposure, the sensitivity of the ultrasound velocity and attenuation coefficient dose-dependent parameters was evaluated. The MAGIC-f polymer gel was irradiated under 1.25 MeV cobalt-60, ranging from 0 to 60 Gy in 2-Gy steps, and received dose uniformity and accuracy of ±2%. After calibration of the ultrasonic systems with a frequency of 500 kHz, the parameters of ultrasound velocity and attenuation coefficient of the irradiated gel samples were measured. According to the dose–response curve, the ability of ultrasonic parameters was evaluated in dose rate readings. Based on a 4-order polynomial curve, fitted on the dose–response parameters of ultrasound velocity and attenuation coefficient and observed at 24 hours after irradiation, ultrasonic parameters had more sensitivity. The sensitivity of the dose–velocity and dose-attenuation coefficient curves was observed as 50 m/s/Gy and 0.06 dB/MHz/Gy over the linear range of 4 to 44 Gy, respectively. The ultrasonic parameters at 5°C, 15°C, and 25°C on the gel dosimeter after 0 to 60 Gy irradiation showed that readings at 25°C have higher sensitivity compared to 15°C and 5°C. Maximum sensitivity time and temperature readings of the MAGIC-f ultrasonic parameters were concluded 24 hours after irradiation and at a temperature of 25°C.

  4. Room temperature lithium metal batteries based on a new Gel Polymer Electrolyte membrane

    Science.gov (United States)

    Sannier, L.; Bouchet, R.; Grugeon, S.; Naudin, E.; Vidal, E.; Tarascon, J.-M.

    A new effective Gel Polymer Electrolyte membrane based on two polymers, the polyethylene oxide (PEO), a poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) copolymer and a plasticizer, the dibutylphtalate (DBP), was realized. This separator membrane was made by adjunction, through lamination, of an industrially made DBP/PVdF-HFP film and a homemade DBP/PEO thin film. Once the plasticizer was removed and the separator gelled by the electrolyte, the PEO enables the formation of a good interface with the lithium while the PVdF-HFP film brings the mechanical strength to the membrane. The electrochemical behavior of lithium batteries based on this bi-layer separator was investigated versus temperature, cycling potential and cycling rate. Owing to the promising results obtained with laboratory cells, a 1 Ah prototype was successfully assembled, and its cycling and rate performances were reported.

  5. Initial study of 3D dose verification of multi-field proton therapy treatment along match line with polymer gel detectors

    Energy Technology Data Exchange (ETDEWEB)

    Avery, S; Freeman, C; Shahnazi, K, E-mail: avery@uphs.upenn.ed [Department of Radiation Oncology, University of Pennsylvania Medical Center, Philadelphia (United States)

    2010-11-01

    This paper is intended as an initial study for quality assurance benefits from polymer gel detectors to proton therapy treatments. Several gel types were explored for stability from batch to batch. The depth dose distributions in the gels were examined with regard to dose dependences and compared to baseline measurements. The results indicate polymer gel detectors may be able to verify dose in three dimensions along match line for proton therapy treatments

  6. Characteristics of a novel polymer gel dosimeter formula for MRI scanning: Dosimetry, toxicity and temporal stability of response.

    Science.gov (United States)

    Abtahi, S M

    2016-09-01

    The present study intended to investigate the composition of a new polymer gel dosimeter. The new composition would be more suitable for a wide range of applications in comparison to polyacrylamide gel dosimeter since its extremely toxic acrylamide has been replaced with less harmful monomer i.e. 2-Acrylamido-2-MethylPropane Sulfonic acid (AMPS). To this end, the PAGAT gel dosimeter formula was used as a basis to test the new formulation of polymer gel dosimeter with a different monomer (AMPS) instead of acrylamide by using the %6T and %50C to the formula. The new formulation was named PAMPSGAT (Poly AMPS, Gelatin and THPC) polymer gel dosimeter. Moreover, the MRI response (R2) of dosimeters was analyzed in terms of different dose range as well as post-irradiation time. The results indicated that the dose-response (R2) of AMPS/Bis had a linear trend over a wide dose range. Furthermore, the results showed an acceptable temporal stability for the new polymer gel dosimeter.

  7. Sensitivity calibration procedures in optical-CT scanning of BANG 3 polymer gel dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Y.; Wuu, Cheng-Shie; Maryanski, Marek J. [Department of Radiation Oncology, Columbia University, New York, New York 10032 (United States); Department of Radiation Oncology, Columbia University, New York, New York 10032 and MGS Research Inc., Madison, Connecticut 06443 (United States)

    2010-02-15

    The dose response of the BANG 3 polymer gel dosimeter (MGS Research Inc., Madison, CT) was studied using the OCTOPUS laser CT scanner (MGS Research Inc., Madison, CT). Six 17 cm diameter and 12 cm high Barex cylinders, and 18 small glass vials were used to house the gel. The gel phantoms were irradiated with 6 and 10 MV photons, as well as 12 and 16 MeV electrons using a Varian Clinac 2100EX. Three calibration methods were used to obtain the dose response curves: (a) Optical density measurements on the 18 glass vials irradiated with graded doses from 0 to 4 Gy using 6 or 10 MV large field irradiations; (b) optical-CT scanning of Barex cylinders irradiated with graded doses (0.5, 1, 1.5, and 2 Gy) from four adjacent 4x4 cm{sup 2} photon fields or 6x6 cm{sup 2} electron fields; and (c) percent depth dose (PDD) comparison of optical-CT scans with ion chamber measurements for 6x6 cm{sup 2}, 12 and 16 MeV electron fields. The dose response of the BANG 3 gel was found to be linear and energy independent within the uncertainties of the experimental methods (about 3%). The slopes of the linearly fitted dose response curves (dose sensitivities) from the four field irradiations (0.0752{+-}3%, 0.0756{+-}3%, 0.0767{+-}3%, and 0.0759{+-}3% cm{sup -1} Gy{sup -1}) and the PDD matching methods (0.0768{+-}3% and 0.0761{+-}3% cm{sup -1} Gy{sup -1}) agree within 2.2%, indicating a good reproducibility of the gel dose response within phantoms of the same geometry. The dose sensitivities from the glass vial approach are different from those of the cylindrical Barex phantoms by more than 30%, owing probably to the difference in temperature inside the two types of phantoms during gel formation and irradiation, and possible oxygen contamination of the glass vial walls. The dose response curve obtained from the PDD matching approach with 16 MeV electron field was used to calibrate the gel phantom irradiated with the 12 MeV, 6x6 cm{sup 2} electron field. Three-dimensional dose distributions

  8. Light-activated, in situ forming gel for sustained suprachoroidal delivery of bevacizumab.

    Science.gov (United States)

    Tyagi, Puneet; Barros, Matthew; Stansbury, Jeffrey W; Kompella, Uday B

    2013-08-05

    A light-activated polycaprolactone dimethacrylate (PCM) and hydroxyethyl methacrylate (HEMA) based gel network was developed to sustain the release of stable, active bevacizumab (an anti-VEGF antibody used to treat choroidal neovascularization) and used to assess sustained ex vivo delivery in rabbit eyes and in vivo delivery in rat eyes following in situ gel formation in the suprachoroidal space. PCM was synthesized from polycaprolactone diol (PCD) and evaluated using NMR spectroscopy. PCM was used to cross-link HEMA in the presence of 365 nm UV light and 2,2-dimethoxy-2-phenylacetophenone (DMPA) as a photoinitiator. Bevacizumab was entrapped in the gel using three different cross-linking durations of 3, 7, and 10 min. In vitro release of bevacizumab in PBS pH 7.4 at 37 °C during a 4 month study was quantified using a VEGF-binding based ELISA. The stability of released bevacizumab was monitored by size exclusion chromatography (SEC) and circular dichroism. Alexa Fluor 488 dye conjugated bevacizumab mixed with polymers was injected suprachoroidally in rabbit eyes to study the effect of different cross-linking durations on the spread of the dye conjugated bevacizumab. In vivo delivery was assessed in Sprague-Dawley (SD) rats by injecting Alexa Fluor 488 dye conjugated bevacizumab mixed with polymers followed by cross-linking for 10 min. Spread in the rabbit eyes and in vivo delivery in rat eyes was monitored noninvasively using a fundus camera and Fluorotron Master. The formation of PCM was confirmed by the disappearance of hydroxyl peak in NMR spectra. A cross-linking duration of 10 min resulted in a burst release of 21% of bevacizumab. Other cross-linking durations had ≥62% burst release. Bevacizumab release from 10 min cross-linked gel was sustained for ∼4 months. Release samples contained ≥96.1% of bevacizumab in the monomeric form as observed in SEC chromatograms. Circular dichroism confirmed that secondary β-sheet structure of bevacizumab was maintained

  9. Light activated, In situ Forming Gel for Sustained Suprachoroidal Delivery of Bevacizumab

    Science.gov (United States)

    Tyagi, Puneet; Barros, Matthew; Stansbury, Jeffrey W.; Kompella, Uday B.

    2014-01-01

    Purpose To develop a light activated polycaprolactone dimethacrylate and hydroxyethyl methacrylate based gel network that sustains the release of stable, active bevacizumab (an anti-VEGF antibody used to treat choroidal neovascularization) and to assess sustained ex vivo delivery in rabbit eyes and in vivo delivery in rat eyes following in situ gel formation in the suprachoroidal space. Methods Polycaprolactone dimethacrylate (PCM) was synthesized from polycaprolactone diol (PCD) and evaluated using NMR spectroscopy. PCM was used to cross-link hydroxyethyl methacrylate (HEMA) in the presence of 365 nm UV light and 2, 2-dimethoxy-2-phenylacetophenone (DMPA) as a photoinitiator. Bevacizumab was entrapped in the gel using 3 different cross-linking durations of 3, 7, and 10 minutes. In vitro release of bevacizumab in PBS pH 7.4 at 37°C during a 4 months study was quantified using a VEGF-binding based ELISA. Stability of released bevacizumab was monitored by size exclusion chromatography (SEC) and circular dichroism. Alexa Fluor® 488 dye conjugated bevacizumab mixed with polymers was injected suprachoroidally in rabbit eyes to study the effect of different cross-linking durations on the spread of the dye conjugated bevacizumab. In vivo delivery was assessed in Sprague Dawley (SD) rats by injecting Alexa Fluor® 488 dye conjugated bevacizumab mixed with polymers followed by cross-linking for 10 minutes. Spread in the rabbit eyes and in vivo delivery in rat eyes was monitored noninvasively using a fundus camera and Fluorotron Master™. Results Formation of PCM was confirmed by the disappearance of hydroxyl peak in NMR spectra. Cross-linking duration of 10 minutes resulted in a burst release of 21 % of bevacizumab. Other cross-linking durations had ≥ 62 % burst release. Bevacizumab release from 10 minute cross-linked gel was sustained for ∼ 4 months. Release samples contained ≥ 96.1 % of bevacizumab in the monomeric form as observed in SEC chromatograms. Circular

  10. Preparation and characterization of PAN–KI complexed gel polymer electrolytes for solid-state battery applications

    Indian Academy of Sciences (India)

    N KRISHNA JYOTHI; K K VENKATARATNAM; P NARAYANA MURTY; K VIJAYA KUMAR

    2016-08-01

    The free standing and dimensionally stable gel polymer electrolyte films of polyacrylonitrile (PAN): potassium iodide (KI) of different compositions, using ethylene carbonate as a plasticizer and dimethyl formamide as solvent, are prepared by adopting ‘solution casting technique’ and these films are examined for their conductivities. The structural, miscibility and the chemical rapport between PAN and KI are investigated using X-ray diffraction, Fourier transform infrared spectroscopy and differential scanning calorimetry methods. The conductivity is enhanced with the increase in KI concentration and temperature. The maximum conductivity at 30$^{\\circ}$C is found to be $2.089 \\times 10^{−5}$ S cm$^{−1}$ for PAN:KI (70:30) wt%, which is nine orders greater than that of pure PAN (${\\lt}10^{−14}$ S cm$^{−1}$). The conductivity-temperature dependence of these polymer electrolyte films obeys Arrhenius behaviour with activation energy ranging from 0.358 to 0.478 eV. The conducting carriers of charge transport in these polymer electrolyte films are identified by Wagner’s polarization technique and it is found that the charge transport is predominantlydue to ions. The better conducting sample is used to fabricate the battery with configuration K/PAN $+$ KI/I$_2$ $+$ C $+$ electrolyte and good discharge characteristics of battery are observed.

  11. Diced electrophoresis gel assay for screening enzymes with specified activities.

    Science.gov (United States)

    Komatsu, Toru; Hanaoka, Kenjiro; Adibekian, Alexander; Yoshioka, Kentaro; Terai, Takuya; Ueno, Tasuku; Kawaguchi, Mitsuyasu; Cravatt, Benjamin F; Nagano, Tetsuo

    2013-04-24

    We have established the diced electrophoresis gel (DEG) assay as a proteome-wide screening tool to identify enzymes with activities of interest using turnover-based fluorescent substrates. The method utilizes the combination of native polyacrylamide gel electrophoresis (PAGE) with a multiwell-plate-based fluorometric assay to find protein spots with the specified activity. By developing fluorescent substrates that mimic the structure of neutrophil chemoattractants, we could identify enzymes involved in metabolic inactivation of the chemoattractants.

  12. On the development of a VIPARnd radiotherapy 3D polymer gel dosimeter

    Science.gov (United States)

    Kozicki, Marek; Jaszczak, Malwina; Maras, Piotr; Dudek, Mariusz; Cłapa, Marian

    2017-02-01

    This work presents an improvement of the VIPARnd (‘nd’ stands for ‘normoxic, double’, or VIP) polymer gel dosimeter. The gel composition was altered by increasing the concentration of the monomeric components, N-vinylpyrrolidone (NVP) and N,N‧-methylenebisacrylamide (MBA), in co-solvent solutions. The optimal composition (VIPARCT, where ‘CT’ stands for computed tomography, or VIC) comprised: 17% NVP, 8% MBA, 12% t-BuOH, 7.5% gelatine, 0.007% ascorbic acid, 0.0008% CuSO4  ×  5H2O and 0.02% hydroquinone. The following characteristics of VIC were achieved: (i) linear dose range of 0.9_30 Gy, (ii) saturation for radiation doses of over 50 Gy, (iii) threshold dose of about 0.5 Gy, (iv) dose sensitivity of 0.171 Gy-1 s-1, which is roughly 2.2 times higher than that of VIP (for nuclear magnetic resonance measurements). It was also found that VIC is dose- rate-independent, and its dose response does not alter if the radiation source is changed from electrons to photons for external beam radiotherapy. The gel responded similarly to irradiation with small changes in radiation energy but was sensitive to larger energy changes. The VIC gel retained temporal stability from 20 h until at least 10 d after irradiation, whereas spatial stability was retained from 20 h until at least 6 d after irradiation. The scheme adopted for VIC manufacturing yields repeatable gels in terms of radiation dose response. The VIC was also shown to perform better than VIP using x-ray computed tomography as a readout method; the dose sensitivity of VIC (0.397 HU Gy-1) was 1.5 times higher than that of VIP. Also, the dose resolution of VIC was better than that of VIP in the whole dose range examined.

  13. C1-inhibitor polymers activate the FXII-dependent kallikrein-kinin system

    DEFF Research Database (Denmark)

    Elenius Madsen, Daniel; Sidelmann, Johannes Jakobsen; Biltoft, Daniel

    2015-01-01

    attacks. HAE is caused by mutations in the C1-inh encoding gene, and we recently demonstrated that some mutations give rise to the presence of polymerized C1-inh in the plasma of HAE patients. METHODS: C1-inh polymers corresponding to the size of polymers observed in vivo were produced using heat...... denaturation and gel filtration. The ability of these polymers to facilitate FXII activation was assessed in vitro in an FXII activation bandshift assay. After spiking of plasma with C1-inh polymers, kallikrein generation was analyzed in a global kallikrein generation method. Prekallikrein consumption...... in the entire Danish HAE cohort was analyzed using an ELISA method. RESULTS: C1-inh polymers mediated FXII activation, and a dose dependent kallikrein generation in plasma spiked with C1-inh polymers. An increased (pre)kallikrein consumption was observed in plasma samples from HAE patients presenting with C1...

  14. Cross-linked Composite Gel Polymer Electrolyte using Mesoporous Methacrylate-Functionalized SiO2 Nanoparticles for Lithium-Ion Polymer Batteries

    Science.gov (United States)

    Shin, Won-Kyung; Cho, Jinhyun; Kannan, Aravindaraj G.; Lee, Yoon-Sung; Kim, Dong-Won

    2016-05-01

    Liquid electrolytes composed of lithium salt in a mixture of organic solvents have been widely used for lithium-ion batteries. However, the high flammability of the organic solvents can lead to thermal runaway and explosions if the system is accidentally subjected to a short circuit or experiences local overheating. In this work, a cross-linked composite gel polymer electrolyte was prepared and applied to lithium-ion polymer cells as a safer and more reliable electrolyte. Mesoporous SiO2 nanoparticles containing reactive methacrylate groups as cross-linking sites were synthesized and dispersed into the fibrous polyacrylonitrile membrane. They directly reacted with gel electrolyte precursors containing tri(ethylene glycol) diacrylate, resulting in the formation of a cross-linked composite gel polymer electrolyte with high ionic conductivity and favorable interfacial characteristics. The mesoporous SiO2 particles also served as HF scavengers to reduce the HF content in the electrolyte at high temperature. As a result, the cycling performance of the lithium-ion polymer cells with cross-linked composite gel polymer electrolytes employing methacrylate-functionalized mesoporous SiO2 nanoparticles was remarkably improved at elevated temperatures.

  15. Cross-linked Composite Gel Polymer Electrolyte using Mesoporous Methacrylate-Functionalized SiO2 Nanoparticles for Lithium-Ion Polymer Batteries.

    Science.gov (United States)

    Shin, Won-Kyung; Cho, Jinhyun; Kannan, Aravindaraj G; Lee, Yoon-Sung; Kim, Dong-Won

    2016-05-18

    Liquid electrolytes composed of lithium salt in a mixture of organic solvents have been widely used for lithium-ion batteries. However, the high flammability of the organic solvents can lead to thermal runaway and explosions if the system is accidentally subjected to a short circuit or experiences local overheating. In this work, a cross-linked composite gel polymer electrolyte was prepared and applied to lithium-ion polymer cells as a safer and more reliable electrolyte. Mesoporous SiO2 nanoparticles containing reactive methacrylate groups as cross-linking sites were synthesized and dispersed into the fibrous polyacrylonitrile membrane. They directly reacted with gel electrolyte precursors containing tri(ethylene glycol) diacrylate, resulting in the formation of a cross-linked composite gel polymer electrolyte with high ionic conductivity and favorable interfacial characteristics. The mesoporous SiO2 particles also served as HF scavengers to reduce the HF content in the electrolyte at high temperature. As a result, the cycling performance of the lithium-ion polymer cells with cross-linked composite gel polymer electrolytes employing methacrylate-functionalized mesoporous SiO2 nanoparticles was remarkably improved at elevated temperatures.

  16. Cross-linked Composite Gel Polymer Electrolyte using Mesoporous Methacrylate-Functionalized SiO2 Nanoparticles for Lithium-Ion Polymer Batteries

    Science.gov (United States)

    Shin, Won-Kyung; Cho, Jinhyun; Kannan, Aravindaraj G.; Lee, Yoon-Sung; Kim, Dong-Won

    2016-01-01

    Liquid electrolytes composed of lithium salt in a mixture of organic solvents have been widely used for lithium-ion batteries. However, the high flammability of the organic solvents can lead to thermal runaway and explosions if the system is accidentally subjected to a short circuit or experiences local overheating. In this work, a cross-linked composite gel polymer electrolyte was prepared and applied to lithium-ion polymer cells as a safer and more reliable electrolyte. Mesoporous SiO2 nanoparticles containing reactive methacrylate groups as cross-linking sites were synthesized and dispersed into the fibrous polyacrylonitrile membrane. They directly reacted with gel electrolyte precursors containing tri(ethylene glycol) diacrylate, resulting in the formation of a cross-linked composite gel polymer electrolyte with high ionic conductivity and favorable interfacial characteristics. The mesoporous SiO2 particles also served as HF scavengers to reduce the HF content in the electrolyte at high temperature. As a result, the cycling performance of the lithium-ion polymer cells with cross-linked composite gel polymer electrolytes employing methacrylate-functionalized mesoporous SiO2 nanoparticles was remarkably improved at elevated temperatures. PMID:27189842

  17. Multifunctional Free-Standing Gel Polymer Electrolyte with Carbon Nanofiber Interlayers for High-Performance Lithium-Sulfur Batteries.

    Science.gov (United States)

    Choi, Sinho; Song, Jianjun; Wang, Chengyin; Park, Soojin; Wang, Guoxiu

    2017-07-04

    Free-standing trimethylolpropane ethoxylate triacrylate gel polymer electrolyte is synthesized by a chemical cross-linking process and used as an electrolyte and separator membrane in lithium-sulfur batteries. The cross linked gel polymer electrolyte also exhibited a stable geometric size retention of 95 % at the high temperature of 130 °C. The as-prepared gel polymer electrolyte membrane with carbon nanofibers interlayer can effectively prevent polysulfide dissolution and shuttle effect, leading to significantly enhanced electrochemical properties, including high capacity and cycling stability, with an enhanced specific capacity of 790 mA h g(-1) after 100 cycles. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Verification of the 3D dose distribution in spinal radiosurgery by using a BANG3 polymer gel dosimeter

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dae-Hong; Kim, Hee-Joung [Yonsei University, Wonju (Korea, Republic of); Lee, Dong-Joon [Inje University, Goyang (Korea, Republic of)

    2012-01-15

    In intensity-modulated radiosurgery (IMRS) treatment, radiation delivery techniques require the ability to accurately verify complex three-dimensional (3D) dose distributions. This study was designed to evaluate and verify dosimetry generated from gels, films, and treatment planning systems. In this study, commercially available BANG3 polymer gel was used to confirm the accuracy of the treatment plan and to assess the dosimetric uncertainty of the radiosurgery procedure. BANG3 gels that are read with R{sub 2} magnetic resonance (MR) imaging mapping are useful options. The gel is a tissue equivalent, and the relaxation ratio measured using MR imaging is proportional to the dose absorbed in the gel. A cylindrical container (5 inch deep, 7 inch high) filled with BANG3 gel was mounted in a cubic phantom (The EASY CUBE, Euromechanics, Schwarzenbruck, Germany). We then carried out the same process using the gel and gafchromic film as would be used for a patient with metastatic T-spine cancer by using a Novalis Radiosurgery system (Brain LAB Inc., Germany). Our experimental results provided the dose distribution and the radiation delivery precision. Comparisons of the measured and the calculated relative dose distributions showed good agreement in the high-dose region with differences of 2 mm. BANG3 polymer gel dosimetry can be useful for the verification of clinical treatment radiosurgery plans.

  19. A novel polymer gel for the delivery of local therapies to intracranial tumors: In vivo safety evaluation.

    Science.gov (United States)

    Gerber, David E; Gallia, Gary L; Tyler, Betty M; Eberhart, Charles G; Royer, Gar; Grossman, Stuart A

    2011-12-01

    The treatment of intracranial malignancies is limited by the ability of systemically administered therapies to cross the blood-brain barrier. Royer resorbable matrix, or R-Gel, is a dextran polymer administered in liquid form via needle injection. Within minutes of preparation, the polymer forms a gel and subsequently solidifies, thereby conforming to the dimensions of the injection cavity. R-Gel can accommodate a wide variety of therapeutic agents that may provide new options for local treatment delivery. This preclinical study evaluates the neurotoxicity of R-Gel implanted in the rat brain. Fifteen rats underwent intracranial administration of R-Gel (N = 9) or saline (N = 6) were monitored for systemic and neurotoxicity, and sacrificed at pre-determined time points. Animals that received the R-Gel injection demonstrated no behavioral changes or weight loss. Histopathologic analysis revealed an inflammatory response in both groups on day 3 and day 7 after implantation, which resolved by day 42. These results suggest that intracranial R-Gel is well tolerated. Therapeutic studies of chemotherapy-complexed R-Gel are underway. Copyright © 2011 Wiley Periodicals, Inc.

  20. Cheap glass fiber mats as a matrix of gel polymer electrolytes for lithium ion batteries.

    Science.gov (United States)

    Zhu, Yusong; Wang, Faxing; Liu, Lili; Xiao, Shiyin; Yang, Yaqiong; Wu, Yuping

    2013-11-12

    Lithium ion batteries (LIBs) are going to play more important roles in electric vehicles and smart grids. The safety of the current LIBs of large capacity has been remaining a challenge due to the existence of large amounts of organic liquid electrolytes. Gel polymer electrolytes (GPEs) have been tried to replace the organic electrolyte to improve their safety. However, the application of GPEs is handicapped by their poor mechanical strength and high cost. Here, we report an economic gel-type composite membrane with high safety and good mechanical strength based on glass fiber mats, which are separator for lead-acid batteries. The gelled membrane exhibits high ionic conductivity (1.13 mS cm(-1)), high Li(+) ion transference number (0.56) and wide electrochemical window. Its electrochemical performance is evaluated by LiFePO4 cathode with good cycling. The results show this gel-type composite membrane has great attraction to the large-capacity LIBs requiring high safety with low cost.

  1. Cheap glass fiber mats as a matrix of gel polymer electrolytes for lithium ion batteries

    Science.gov (United States)

    Zhu, Yusong; Wang, Faxing; Liu, Lili; Xiao, Shiyin; Yang, Yaqiong; Wu, Yuping

    2013-11-01

    Lithium ion batteries (LIBs) are going to play more important roles in electric vehicles and smart grids. The safety of the current LIBs of large capacity has been remaining a challenge due to the existence of large amounts of organic liquid electrolytes. Gel polymer electrolytes (GPEs) have been tried to replace the organic electrolyte to improve their safety. However, the application of GPEs is handicapped by their poor mechanical strength and high cost. Here, we report an economic gel-type composite membrane with high safety and good mechanical strength based on glass fiber mats, which are separator for lead-acid batteries. The gelled membrane exhibits high ionic conductivity (1.13 mS cm-1), high Li+ ion transference number (0.56) and wide electrochemical window. Its electrochemical performance is evaluated by LiFePO4 cathode with good cycling. The results show this gel-type composite membrane has great attraction to the large-capacity LIBs requiring high safety with low cost.

  2. Electrical and electrochemical properties of magnesium ion conducting composite gel polymer electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, G P; Hashmi, S A [Department of Physics and Astrophysics, University of Delhi, Delhi-110007 (India); Agrawal, R C, E-mail: sahashmi@physics.du.ac.i [School of Studies in Physics, Pt. Ravishankar Shukla University, Raipur-492010, Chhattisgarh (India)

    2010-06-30

    The effect of micro- and nano-sized MgO and nano-sized SiO{sub 2} dispersion on the electrical and electrochemical properties of poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) based Mg{sup 2+} ion conducting gel polymer electrolyte has been investigated. The gel electrolytes have been characterized using electrical conductivity, cationic transport number (t{sub +}) measurements and cyclic voltammetry. A two-maxima feature has been observed in the 'conductivity versus composition' curve at {approx}3 wt% and 10-15 wt% of the filler contents. The highest conductivity has been obtained for the SiO{sub 2} dispersed gel electrolyte of {approx}1 x 10{sup -2} S cm{sup -1} for 3 wt% and {approx}9 x 10{sup -3} S cm{sup -1} at 15 wt% content. The value of 't{sub +}' is found to be enhanced substantially with increasing amount of MgO (both micro- and nanoparticles), whereas in the case of SiO{sub 2} dispersion the value does not increase substantially. The highest 't{sub +}' value of {approx}0.44 has been obtained for the addition of 10 wt% MgO nanoparticles. The enhancement in 't{sub +}' is explained on the basis of the formation of space-charge regions due to the presence of MgO : Mg{sup 2+}-like species, which supports Mg{sup 2+} ion motion. A substantial increase in the amount of anodic and cathodic peak currents is observed due to the addition of nano-sized MgO particles in the gel polymer electrolyte, whereas in the cases of micrometre-sized MgO and nano-sized SiO{sub 2} the enhancement is not significant. The enhancement in conductivity in SiO{sub 2} dispersed nanocomposite gel electrolyte is predominantly due to anionic motion.

  3. Magnesium ion-conducting gel polymer electrolytes dispersed with nanosized magnesium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, G.P. [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Solid State Ionics Research Laboratory, School of Studies in Physics, Pt. Ravishankar Shukla University, Raipur 492010, C.G. (India); Agrawal, R.C. [Solid State Ionics Research Laboratory, School of Studies in Physics, Pt. Ravishankar Shukla University, Raipur 492010, C.G. (India); Hashmi, S.A. [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)

    2009-05-15

    Experimental investigations are performed on novel magnesium ion-conducting gel polymer electrolyte nanocomposites based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP), dispersed with nanosized magnesium oxide (MgO) particles. The nanocomposite materials are in the form of free-standing films. Various physical and electrochemical analyses demonstrate promising characteristics of these films, suitable as electrolytes in rechargeable magnesium batteries. The optimized material with 3 wt.% MgO offers a maximum electrical conductivity of {proportional_to}8 x 10{sup -3} S cm{sup -1} at room temperature ({proportional_to}25 C) with good thermal and electrochemical stabilities. The ion/filler-polymer interactions and possible conformational changes in host polymer PVdF-HFP due to the liquid electrolyte entrapment and dispersion of nanosized MgO are examined by Fourier transform infrared (FTIR), X-ray diffraction (XRD) and scanning electron microscopic (SEM) methods. The Mg{sup 2+} ion conduction in the gel film is confirmed from the cyclic voltammetry, impedance spectroscopy and transport number measurements. The Mg{sup 2+} ion transport number (t{sub +}) is enhanced substantially and found to have a maximum of {proportional_to}0.44 for the addition of 10 wt.% MgO nanoparticles. The enhancement in t{sub +} is explained on the basis of the formation of space-charge regions due to the presence of MgO:Mg{sup 2+}-like species, that supports Mg{sup 2+} ion motion. (author)

  4. Electrochemical performances of electric double layer capacitor with UV-cured gel polymer electrolyte based on poly[(ethylene glycol)diacrylate]-poly(vinylidene fluoride) blend

    Energy Technology Data Exchange (ETDEWEB)

    Chunmo Yang; Joongkee Lee; Wonil Cho; Byungwon Cho [Korea Inst. of Science and Technology, Eco-Nano Research Center, Seoul (Korea); Jehbeck Ju [Hongik Univ., Dept. of Chemical Engineering, Seoul (Korea)

    2005-03-01

    Poly[(ethylene glycol)diacrylate]-poly(vinylidene fluoride), a gel polymer blend with ethylene carbonate:dimethyl carbonate:ethylmethyl carbonate (EC:DMC:EMC, 1:1:1 volume ratio) and containing 1.0 M of lithium hexafluoro phosphate (LiPF{sub 6}) as liquid components, is employed as a gel polymer electrolyte for an electric double layer capacitor (EDLC). Its electrochemical characteristics is compared with that of liquid organic electrolyte mixture of ethylene carbonate, dimethyl carbonate and ethylmethyl carbonate in a 1:1:1 volume ratio containing 1.0 M LiPF{sub 6} salt. The specific surface area of the activated carbon powder as an active material is 1908 m{sup 2}/g. Liquid poly[(ethylene glycol)diacrylate] (PEGDA) oligomer with a high retention capability of liquid electrolytes is cured by UV irradiation and poly(vinylidene fluoride)-hexafluoropropylene (PVdF-HFP) copolymer with a porous structure endows polymer matrix with high mechanical strength. The specific capacitance of EDLC using the gel polymer electrolyte (GPE-EDLC) shows 120 F/g, which is better than the liquid organic electrolyte. Good cycling efficiency is observed for a GPE-EDLC with high retention capability of liquid components. The high specific capacitance and good cycling efficiency are most likely due to the polarization resistance of EDLC with the gel polymer electrolyte, which is lower than the liquid organic electrolyte. This may result from the distinguished adhesion between the activated carbon electrode and the gel polymer electrolyte, as well as high retention capability of liquid components. Power densities of GPE-EDLC and LOE-EDLC shows 1.88 kW/kg and 1.21 kW/kg, respectively. However, the energy densities are low in both electrolytes. The GPE-EDLC exhibits rectangular cyclic voltammogram similar to an ideal EDLC within operating voltage range of 0 V-2.5 V. It should be noted that a region of electric double layer means a wide voltage and a rapid formation. Redox currents of both

  5. Electrochemical performances of electric double layer capacitor with UV-cured gel polymer electrolyte based on poly[(ethylene glycol)diacrylate]-poly(vinylidene fluoride) blend

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Chun-Mo [Eco-Nano Research Center, Korea Institute of Science and Technology, Seoul 130-650 (Korea, Republic of)]. E-mail: ycm@kist.re.kr; Ju, Jeh Beck [Department of Chemical Engineering, Hongik University, Seoul 121-791 (Korea, Republic of); Lee, Joong Kee [Eco-Nano Research Center, Korea Institute of Science and Technology, Seoul 130-650 (Korea, Republic of); Cho, Won Il [Eco-Nano Research Center, Korea Institute of Science and Technology, Seoul 130-650 (Korea, Republic of); Cho, Byung Won [Eco-Nano Research Center, Korea Institute of Science and Technology, Seoul 130-650 (Korea, Republic of)

    2005-03-01

    Poly[(ethylene glycol)diacrylate]-poly(vinylidene fluoride), a gel polymer blend with ethylene carbonate:dimethyl carbonate:ethylmethyl carbonate (EC:DMC:EMC, 1:1:1 volume ratio) and containing 1.0 M of lithium hexafluoro phosphate (LiPF{sub 6}) as liquid components, is employed as a gel polymer electrolyte for an electric double layer capacitor (EDLC). Its electrochemical characteristics is compared with that of liquid organic electrolyte mixture of ethylene carbonate, dimethyl carbonate and ethylmethyl carbonate in a 1:1:1 volume ratio containing 1.0 M LiPF{sub 6} salt. The specific surface area of the activated carbon powder as an active material is 1908 m{sup 2}/g. Liquid poly[(ethylene glycol)diacrylate] (PEGDA) oligomer with a high retention capability of liquid electrolytes is cured by UV irradiation and poly(vinylidene fluoride)-hexafluoropropylene (PVdF-HFP) copolymer with a porous structure endows polymer matrix with high mechanical strength. The specific capacitance of EDLC using the gel polymer electrolyte (GPE-EDLC) shows 120 F/g, which is better than the liquid organic electrolyte. Good cycling efficiency is observed for a GPE-EDLC with high retention capability of liquid components. The high specific capacitance and good cycling efficiency are most likely due to the polarization resistance of EDLC with the gel polymer electrolyte, which is lower than the liquid organic electrolyte. This may result from the distinguished adhesion between the activated carbon electrode and the gel polymer electrolyte, as well as high retention capability of liquid components. Power densities of GPE-EDLC and LOE-EDLC shows 1.88 kW/kg and 1.21 kW/kg, respectively. However, the energy densities are low in both electrolytes. The GPE-EDLC exhibits rectangular cyclic voltammogram similar to an ideal EDLC within operating voltage range of 0 V-2.5 V. It should be noted that a region of electric double layer means a wide voltage and a rapid formation. Redox currents of both

  6. Giant Volume Change of Active Gels under Continuous Flow

    Science.gov (United States)

    2014-04-21

    communication17 of BZ droplets and chemical self-organiza- tion,18 the properties and potential of self-oscillating gels in a microfluidic system have yet to be...active gels driven by the Belousov−Zhabotinsky reaction. These results demon- strate that microfluidics offers a useful and facile experimental...soft materials and microfluidic systems. ■ INTRODUCTION This paper reports the use of a continuous reactant flow in a microfluidic system to achieve

  7. Organic silicone sol-gel polymer as a noncovalent carrier of receptor proteins for label-free optical biosensor application.

    Science.gov (United States)

    Ren, Jun; Wang, Linghua; Han, Xiuyou; Cheng, Jianfang; Lv, Huanlin; Wang, Jinyan; Jian, Xigao; Zhao, Mingshan; Jia, Lingyun

    2013-01-23

    Optical biosensing techniques have become of key importance for label-free monitoring of biomolecular interactions in the current proteomics era. Together with an increasing emphasis on high-throughput applications in functional proteomics and drug discovery, there has been demand for facile and generally applicable methods for the immobilization of a wide range of receptor proteins. Here, we developed a polymer platform for microring resonator biosensors, which allows the immobilization of receptor proteins on the surface of waveguide directly without any additional modification. A sol-gel process based on a mixture of three precursors was employed to prepare a liquid hybrid polysiloxane, which was photopatternable for the photocuring process and UV imprint. Waveguide films were prepared on silicon substrates by spin coating and characterized by atomic force microscopy for roughness, and protein adsorption. The results showed that the surface of the polymer film was smooth (rms = 0.658 nm), and exhibited a moderate hydrophobicity with the water contact angle of 97°. Such a hydrophobic extent could provide a necessary binding strength for stable immobilization of proteins on the material surface in various sensing conditions. Biological activity of the immobilized Staphylococcal protein A and its corresponding biosensing performance were demonstrated by its specific recognition of human Immunoglobulin G. This study showed the potential of preparing dense, homogeneous, specific, and stable biosensing surfaces by immobilizing receptor proteins on polymer-based optical devices through the direct physical adsorption method. We expect that such polymer waveguide could be of special interest in developing low-cost and robust optical biosensing platform for multidimensional arrays.

  8. A novel high-performance gel polymer electrolyte membrane basing on electrospinning technique for lithium rechargeable batteries

    Science.gov (United States)

    Wu, Na; Cao, Qi; Wang, Xianyou; Li, Xiaoyun; Deng, Huayang

    2011-10-01

    Nonwoven films of composites of thermoplastic polyurethane (TPU) with different proportion of poly(vinylidene fluoride) (PVdF) (80, 50 and 20%, w/w) are prepared by electrospinning 9 wt% polymer solution at room temperature. Then the gel polymer electrolytes (GPEs) are prepared by soaking the electrospun TPU-PVdF blending membranes in 1 M LiClO4/ethylene carbonate (EC)/propylene carbonate (PC) for 1 h. The gel polymer electrolyte (GPE) shows a maximum ionic conductivity of 3.2 × 10-3 S cm-1 at room temperature and electrochemical stability up to 5.0 V versus Li+/Li for the 50:50 blend ratio of TPU:PVdF system. At the first cycle, it shows a first charge-discharge capacity of 168.9 mAh g-1 when the gel polymer electrolyte (GPE) is evaluated in a Li/PE/lithium iron phosphate (LiFePO4) cell at 0.1 C-rate at 25 °C. TPU-PVdF (50:50, w/w) based gel polymer electrolyte is observed much more suitable than the composite films with other ratios for high-performance lithium rechargeable batteries.

  9. Dynamics of Fractal Cluster Gels with Embedded Active Colloids

    Science.gov (United States)

    Szakasits, Megan E.; Zhang, Wenxuan; Solomon, Michael J.

    2017-08-01

    We find that embedded active colloids increase the ensemble-averaged mean squared displacement of particles in otherwise passively fluctuating fractal cluster gels. The enhancement in dynamics occurs by a mechanism in which the active colloids contribute to the average dynamics both directly through their own active motion and indirectly through their excitation of neighboring passive colloids in the fractal network. Fractal cluster gels are synthesized by addition of magnesium chloride to an initially stable suspension of 1.0 μ m polystyrene colloids in which a dilute concentration of platinum coated Janus colloids has been dispersed. The Janus colloids are thereby incorporated into the fractal network. We measure the ensemble-averaged mean squared displacement of all colloids in the gel before and after the addition of hydrogen peroxide, a fuel that drives diffusiophoretic motion of the Janus particles. The gel mean squared displacement increases by up to a factor of 3 for an active to passive particle ratio of 1 ∶20 and inputted active energy—defined based on the hydrogen peroxide's effect on colloid swim speed and run length—that is up to 9.5 times thermal energy, on a per particle basis. We model the enhancement in gel particle dynamics as the sum of a direct contribution from the displacement of the Janus particles themselves and an indirect contribution from the strain field that the active colloids induce in the surrounding passive particles.

  10. Molecular motors robustly drive active gels to a critically connected state

    CERN Document Server

    Alvarado, Jose; Sharma, Abhinav; MacKintosh, Fred C; Koenderink, Gijsje H

    2013-01-01

    Living systems often exhibit internal driving: active, molecular processes drive nonequilibrium phenomena such as metabolism or migration. Active gels constitute a fascinating class of internally driven matter, where molecular motors exert localized stresses inside polymer networks. There is evidence that network crosslinking is required to allow motors to induce macroscopic contraction. Yet a quantitative understanding of how network connectivity enables contraction is lacking. Here we show experimentally that myosin motors contract crosslinked actin polymer networks to clusters with a scale-free size distribution. This critical behavior occurs over an unexpectedly broad range of crosslink concentrations. To understand this robustness, we develop a quantitative model of contractile networks that takes into account network restructuring: motors reduce connectivity by forcing crosslinks to unbind. Paradoxically, to coordinate global contractions, motor activity should be low. Otherwise, motors drive initially ...

  11. Protocol and cell responses in three-dimensional conductive collagen gel scaffolds with conductive polymer nanofibres for tissue regeneration.

    Science.gov (United States)

    Sirivisoot, Sirinrath; Pareta, Rajesh; Harrison, Benjamin S

    2014-02-06

    It has been established that nerves and skeletal muscles respond and communicate via electrical signals. In regenerative medicine, there is current emphasis on using conductive nanomaterials to enhance electrical conduction through tissue-engineered scaffolds to increase cell differentiation and tissue regeneration. We investigated the role of chemically synthesized polyaniline (PANI) and poly(3,4-ethylenedioxythiophene) (PEDOT) conductive polymer nanofibres for conductive gels. To mimic a naturally derived extracellular matrix for cell growth, type I collagen gels were reconstituted with conductive polymer nanofibres and cells. Cell viability and proliferation of PC-12 cells and human skeletal muscle cells on these three-dimensional conductive collagen gels were evaluated in vitro. PANI and PEDOT nanofibres were found to be cytocompatible with both cell types and the best results (i.e. cell growth and gel electrical conductivity) were obtained with a low concentration (0.5 wt%) of PANI. After 7 days of culture in the conductive gels, the densities of both cell types were similar and comparable to collagen positive controls. Moreover, PC-12 cells were found to differentiate in the conductive hydrogels without the addition of nerve growth factor or electrical stimulation better than collagen control. Importantly, electrical conductivity of the three-dimensional gel scaffolds increased by more than 400% compared with control. The increased conductivity and injectability of the cell-laden collagen gels to injury sites in order to create an electrically conductive extracellular matrix makes these biomaterials very conducive for the regeneration of tissues.

  12. The Antimicrobial Activity of Porphyrin Attached Polymers

    Science.gov (United States)

    Thompson, Lesley

    2008-03-01

    We are interested in testing the antimicrobial activity of a porphyrin that is attached to a polymer. The porphyrin (5-(4-carboxyphenyl)-10,15,20-tris-(4-pryridyl)) was synthesized from methyl 4-formyl benzoate, 4-pyridinecarboxaldehyde, and pyrrole and attached to a copolymer of polystyrene/poly(vinyl benzyl chloride), which was synthesized by free radical polymerization. The antimicrobial activity of the polymer-attached porphyrin was then determined for gram-negative E. Coli grown to 0.80 OD. In this procedure, glass slides were coated with polymer-attached porphyrin via dip-coating, and the E. Coli bacteria were plated in Luria Broth media. The plates were subsequently exposed to light overnight before they were incubated as porphyrins act as photo-sensitizers when irradiated with light. The polymer-attached porphyrin did exhibit antimicrobial activity and parameters that affect its efficiency will be discussed.

  13. Effects of mechanical stress on the volume phase transition of poly(N-isopropylacrylamide) based polymer gels

    Science.gov (United States)

    Takigawa, T.; Araki, H.; Takahashi, K.; Masuda, T.

    2000-11-01

    The effects of mechanical stress on the volume phase transition of a poly(N-isopropylacrylamide) (PNIPA) gel as well as a copolymer gel composed of N-isopropylacrylamide (NIPA) and sodium acrylate (SA) were investigated in the relatively low stress region. The PNIPA gel without elongational stress showed the behavior close to the second order phase transition. The character of the first order transition became clear under tension, and the transition temperature increased with increasing applied stress. Similar behavior was observed for the NIPA-SA copolymer gel, but the copolymer gel showed the first order transition in the whole stress range investigated. The thermodynamical linear region, where the transition temperature varies linearly with applied stress, was narrower than the mechanical linear region determined by the stress-strain relation of the gels. The change in the transition behavior by the application of the mechanical stress originated chiefly from the volume change in the gels by the applied mechanical stress. It was found that the curve of the transition temperature against applied stress corresponds to the phase boundary between the swollen and collapsed phases for the gels. On the basis of the experimental data, a phenomenological model describing the volume phase transition of the polymer gels is proposed in the frame of the Landau-type free energy expression.

  14. Effect of thiolated polymers to textural and mucoadhesive properties of vaginal gel formulations prepared with polycarbophil and chitosan.

    Science.gov (United States)

    Cevher, Erdal; Sensoy, Demet; Taha, Mohamed A M; Araman, Ahmet

    2008-01-01

    The aim of this study was to design and evaluate of mucoadhesive gel formulations for the vaginal application of clomiphene citrate (CLM) for local treatment of human papilloma virus (HPV) infections. Chitosan (CHI) and polycarbophil (PC) were covalently modified using the thioglycolic acid and L-cysteine, respectively. The formation of thiol conjugates of chitosan (CHI-TG) and polycarbophil (PC-CYS) were confirmed by FT-IR analysis and PC-CYS and CHI-TG were found to have 148.42 +/- 4.16 and 41.17 +/- 2.34 micromol of thiol groups per gram of polymer, respectively. One percent CLM gels were prepared by combination of various concentrations of PC and CHI with thiolated conjugates of these polymers. Hardness, compressibility, elasticity, adhesiveness and cohesiveness of the gels were measured by Texture profile analysis and the vaginal mucoadhesion was investigated by mucoadhesion test. The increasing in the amount of the thiol conjugates was found to enhance the elasticity, cohesiveness, adhesiveness and mucoadhesion of the gel formulations but not their hardness and compressibility when compared to gels prepared using their respective parent formulations. Slower release rate of CLM from gels was achieved when the polymer concentrations were increased in the gel formulations. PC and its thiol conjugate were found to prolong the release of CLM longer than 70 h unlike gel formulations prepared using CHI and its thiol conjugate which were able to release CLM up to 12 h. Stability of CLM was preserved during the 3 month stability analysis under controlled room temperature and accelerated conditions.

  15. Ionic transport and electrochemical stability of PVDF-HFP based gel polymer electrolytes

    Science.gov (United States)

    Rosdi, A.; Zainol, N. H.; Osman, Z.

    2016-02-01

    The gel polymer electrolytes (GPEs) samples consisting of polyvinylidenefluoride-co-hexafluoropropylene (PVDF-HFP), ethylene carbonate (EC) and propylene carbonate (PC) with different concentrations of magnesium triflate salt, Mg(CF3SO3)2 were prepared using the solution casting technique. The ionic conductivity of the GPEs was studied by using a.c impedance spectroscopy and the sample containing 20 wt% salt exhibited the highest conductivity of 5.11 × l0-3 Scm-1. Ionic transport number of the GPEs shows that the samples contain ionic species as main charge carrier while cationic transport number for the highest conducting sample was found to be 0.27. The electrochemical properties of the GPEs were studied using Linear Sweep Voltammetry (LSV) and Cyclic Voltammetry (CV). The GPEs show high electrochemical stability ˜3.5V (versus Mg2+/Mg) where the highest conducting sample exhibited the highest stability.

  16. Microencapsulation of probiotic bacteria using thermo-sensitive sol-gel polymers for powdered infant formula.

    Science.gov (United States)

    Penhasi, Adel

    2015-01-01

    In this study the application of thermo-sensitive sol-gel polymers in microencapsulation formulation of probiotic bacteria, Bifidobacterium animalis spp lactis, for powdered infant formula (PIF), which is reconstituted at 70 °C, has been assessed. A double-layered microcapsule containing hydroxypropyl methyl cellulose (HPMC) as an inner layer and an outer layer, as the smart coating layer, based on a combination of hydroxypropyl cellulose (HPC) and poloxamer was designed. Generally, this specific microencapsulation provided superior protection against the reconstitution temperature. A high molecular weight of HPC and a greater thickness of the smart coating layer resulted in a delayed release of the bacteria from the microcapsules especially in the PIF composition. However, this was compensated by a high stability of the bacteria at 70 °C. Both the surface texture and particle size distribution of microcapsules have been respectively characterised by scanning electron microscopy and particle size analysis.

  17. Rheological and textural properties of microemulsion-based polymer gels with indomethacin.

    Science.gov (United States)

    Froelich, Anna; Osmałek, Tomasz; Kunstman, Paweł; Roszak, Rafał; Białas, Wojciech

    2016-01-01

    In this paper, we present novel microemulsion (ME)-based semisolid polymer gels designed for topical administration of poorly water soluble non-steroidal anti-inflammatory drugs. Indomethacin (IND) was used as a model compound. The ME consisted of castor oil, water, Tween®80 as a surfactant and ethanol as cosurfactant. To obtain the desired consistency of the formulations Carbopol®960 was applied as a thickening agent. The aim of the study was to analyze in detail the mechanical properties of the obtained systems, with special attention paid to the features crucial for topical application. The rheological and textural experiments performed for samples with and without the incorporated drug clearly indicate that flow characteristics, viscoelastic properties and texture profiles were affected by the presence of IND. Novel semisolid formulations with IND described for the first time in this paper can be considered as an alternative for commercially available conventional topical dosage forms.

  18. STUDY OF THE DIGESTED SLUDGE DEWATERING EFFECTIVENESS USING POLYELECTROLYTE GEL BASED ON ORGANIC POLYMERS

    Directory of Open Access Journals (Sweden)

    Marcin Głodniok

    2016-02-01

    Full Text Available The paper addresses the problems connected with sewage sludge dewatering. The premise of the study was the analysis of whether there are opportunities to increase the efficiency of dewatering sludge, a relatively low-cost involving the use of innovative polymers. The authors analyzed the impact of the new type of polyelectrolyte gel on the effectiveness of dewatering sludge. Laboratory studies were carried out at polyelectrolyte dose selection and laboratory testing on the press chamber designed to simulate the actual operation of sludge dewatering system. Two different doses of polyelectrolyte were tested for dose I – 4 ml/m3 and dose II – 8 ml/m3. The conducted analysis on laboratory press showed an increase of sludge dewatering efficiency by about 2% for dose no. I and by about 13% for dose no. II, in comparison to the test without polyelectrolyte.

  19. Thermal and aqua-reserve characteristics of an aqua-reserver using a super-absorbent polymer gel; Kokyusuisei jushi wo mochiita hosuizai no hosui netsutokusei

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Z. [Tokyo Metropolitan Univ., Tokyo (Japan); Asako, Y.; Yamaguchi, Y.; Yoshida, H. [Tokyo Metropolitan Univ., Tokyo (Japan). Faculty of Technology

    1997-09-25

    This paper describes thermal and aqua-reserve characteristics of a super-absorbent polymer gel which absorbs an aqueous solution of calcium chloride as a heat absorbent in a firewall during fire. Only gels which absorbed 10 to 40 mass% of the solutions were tested. The absorbency of the polymer and latent heat of the gel were measured using a thermal analyzer of TG/DTA. To obtain the aqua-reserve characteristics, changes in weight of the gel which was left in a room under controlled temperature was measured. Also, an equilibrium concentration of the calcium chloride solution in the gel was obtained. 8 refs., 12 figs., 3 tabs.

  20. Efficacy of Entomopathogenic Nematodes and Sprayable Polymer Gel Against Crucifer Flea Beetle (Coleoptera: Chrysomelidae) on Canola.

    Science.gov (United States)

    Antwi, Frank B; Reddy, Gadi V P

    2016-08-01

    The crucifer flea beetle, Phyllotreta cruciferae (Goeze), is a key pest of canola (Brassica napus L.) in the northern Great Plains of North America. The efficacies of entomopathogenic nematodes (Steinernema spp. and Heterorhabditis spp.), a sprayable polymer gel, and a combination of both were assessed on canola for flea beetle management. Plots were treated soon after colonization by adult flea beetles, when canola was in the cotyledon to one-leaf stage. Ten plants along a 3.6-m section of row were selected and rated at pre-treatment and 7 and 14 d post treatment using the damage-rating scheme advanced by the European Plant Protection Organization, where 1 = 0%, 2 = 2%, 3 = 5%, 4 = 10%, and 5 = 25% leaf area injury. Under moderate flea beetle feeding pressure (1-3.3% leaf area damaged), seeds treated with Gaucho 600 (Bayer CropScience LP Raleigh, NC) (imidacloprid) produced the highest yield (843.2 kg/ha). Meanwhile, Barricade (Barricade International, Inc. Hobe Sound, FL) (polymer gel; 1%) + Scanmask (BioLogic Company Inc, Willow Hill, PA) (Steinernema feltiae) resulted in the highest yields: 1020.8 kg/ha under high (2.0-5.3% leaf area damaged), and 670.2 kg/ha at extremely high (4.3-8.6 % leaf area damaged) feeding pressure. Our results suggest that Barricade (1%) + Scanmask (S. feltiae) can serve as an alternative to the conventional chemical seed treatment. Moreover, Scanmask (S. feltiae) can be used to complement the effects of seed treatment after its protection has run out.

  1. Whisker formation of $\\pi$-stacking long polymers: Gel transition in absence of mechanically percolating structures

    CERN Document Server

    Villalobos, Gabriel

    2016-01-01

    We present numerical evidence showing a gel transition occurring in the absence of mechanically percolating structures. The system under consideration consists of long slender laths who interact mostly in the direction perpendicular to their areas; self-assembling into ordered aggregates. An example of such system, which inspired this project, is the poly 3 hexylthiophene (P3HT); a polymer used in the construction of solar cells. In this context, the ordered aggregates are known as whiskers. In order to do the numerical oscillatory shear experiments, we have developed a Brownian dynamics model, in which the potential depends on the orientation of the particles, Brownian Orientational Lath moDel (BOLd). It is characterized by a potential energy that depends both on the angle between orientation vectors, along the long axis of the laths, as well as the vectors normal to the plane of the laths; and which has only one energetic parameter. The storage and loss modulus measured here shown the gel transition, even t...

  2. Molecularly imprinted polymer for 2, 4-dichlorophenoxyacetic acid prepared by a sol-gel method

    Indian Academy of Sciences (India)

    Yanli Sun

    2014-07-01

    Based on a sol-gel procedure, a molecularly imprinted polymer (MIP) for 2, 4-dichlorophenoxyacetic acid (2, 4-D) was synthesized, using phenyltrimethoxysilane (PTMOS), aminopropyltriethoxysilane (APTES) as monomers and tetraethoxysilane (TEOS) as cross-linking agent. In addition to the amount of the template, some factors in the sol-gel process: TEOS/APTES/PTMOS molar ratio, H2O/Si molar ratio, CH3CH2OH/Si molar ratio, etc. were investigated in detail. Results show that the optimum conditions for the preparation of the MIPs were 20:1.5:1 (TEOS: APTES: PTMOS), ca. 4 (H2O/Si), ca. 4 (CH3CH2OH/Si), respectively. Effects of various parameters involved in the adsorption process of 2, 4-D on MIP such as incubation time, pH, etc. were also evaluated. It is found that the adsorption attained equilibrium within 3 h, the optimum pH for adsorption was about 7 and the adsorption obeyed Langmuir model. Test results also demonstrated that the present MIP for 2, 4-D had large adsorption capacity (the maximum adsorption concluded from Langmuir model reached 243.3 mg/g) and good selectivity.

  3. Phthaloylchitosan-Based Gel Polymer Electrolytes for Efficient Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    S. N. F. Yusuf

    2014-01-01

    Full Text Available Phthaloylchitosan-based gel polymer electrolytes were prepared with tetrapropylammonium iodide, Pr4NI, as the salt and optimized for conductivity. The electrolyte with the composition of 15.7 wt.% phthaloylchitosan, 31.7 wt.% ethylene carbonate (EC, 3.17 wt.% propylene carbonate (PC, 19.0 wt.% of Pr4NI, and 1.9 wt.% iodine exhibits the highest room temperature ionic conductivity of 5.27 × 10−3 S cm−1. The dye-sensitized solar cell (DSSC fabricated with this electrolyte exhibits an efficiency of 3.5% with JSC of 7.38 mA cm−2, VOC of 0.72 V, and fill factor of 0.66. When various amounts of lithium iodide (LiI were added to the optimized gel electrolyte, the overall conductivity is observed to decrease. However, the efficiency of the DSSC increases to a maximum value of 3.71% when salt ratio of Pr4NI : LiI is 2 : 1. This cell has JSC, VOC and fill factor of 7.25 mA cm−2, 0.77 V and 0.67, respectively.

  4. Mechanochemically-Active Polymer Composites

    Science.gov (United States)

    2013-09-13

    Kelly M. Wiggins, Christopher W. Bielawski. A Mechanochemical Approach to Deracemization, Angewandte Chemie International Edition , (02 2012): 0. doi...design and study of mechanophores, Polymer International , (01 2013): 2. doi: 10.1002/pi.4350 08/28/2008 2.00 S.L. Potisek, D.A. Davis, N.R. Sottos, S.R...Proton-Coupled Mechanochemical Transduction – Mechanogenerating Acids” Fourth International Conference on Self-Healing Materials, Ghent, Belgium, Jun

  5. Effects of Lewis-acid polymer on the electrochemical properties of alkylphosphate-based non-flammable gel electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Lalia, Boor Singh; Yoshimoto, Nobuko; Egashira, Minato; Morita, Masayuki [Department of Applied Chemistry, Graduate School of Science and Engineering, Yamaguchi University, 2-16-1 Tokiwadai, Ube 755-8611 (Japan)

    2009-10-20

    Non-flammable polymer gel electrolytes (NPGE) consisting of 1.0 mol dm{sup -3} (=M) LiBF{sub 4}/EC + DEC + TEP (55:25:20 volume ratio) + PVdF-HFP (EC: ethylene carbonate, DEC: diethyl carbonate, TEP: triethylphosphate, PVdF-HFP: poly(vinyledenefluoride-co-hexafluoropropylene)) have been developed for rechargeable lithium batteries. The effects of addition of Lewis-acid polymer (LAP) with different mole ratio in NPGE have been studied. The addition of LAP improved physico-chemical properties of NPGE, viz ionic conductivity and lithium ion transport number, as well as mechanical and thermal properties. The ionic conductivity of the gel electrolyte containing LAP reached that of the base solution electrolyte (1.0 M LiBF{sub 4}/EC + DEC + TEP (55:25:20)) along with better mechanical properties. Interfacial resistance at Li-metal electrode/NPGE was also improved by introducing LAP in the gel. (author)

  6. Effects of Lewis-acid polymer on the electrochemical properties of alkylphosphate-based non-flammable gel electrolyte

    Science.gov (United States)

    Lalia, Boor Singh; Yoshimoto, Nobuko; Egashira, Minato; Morita, Masayuki

    Non-flammable polymer gel electrolytes (NPGE) consisting of 1.0 mol dm -3 (=M) LiBF 4/EC + DEC + TEP (55:25:20 volume ratio) + PVdF-HFP (EC: ethylene carbonate, DEC: diethyl carbonate, TEP: triethylphosphate, PVdF-HFP: poly(vinyledenefluoride-co-hexafluoropropylene)) have been developed for rechargeable lithium batteries. The effects of addition of Lewis-acid polymer (LAP) with different mole ratio in NPGE have been studied. The addition of LAP improved physico-chemical properties of NPGE, viz ionic conductivity and lithium ion transport number, as well as mechanical and thermal properties. The ionic conductivity of the gel electrolyte containing LAP reached that of the base solution electrolyte (1.0 M LiBF 4/EC + DEC + TEP (55:25:20)) along with better mechanical properties. Interfacial resistance at Li-metal electrode/NPGE was also improved by introducing LAP in the gel.

  7. Molecular structure effects on the post irradiation diffusion in polymer gel dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Mattea, F.; Romero, M.; Strumia, M. [Instituto Multidisciplinario de Biologia Vegetal / CONICET, Universidad Nacional de Cordoba, Departamento de Quimica Organica, Ciudad Universitaria, 5000 Cordoba (Argentina); Vedelago, J. [Laboratorio de Investigaciones e Instrumentacion en Fisica Aplicada a la Medicina e Imagenes por Rayos X, Laboratorio 448 FaMAF - UNC, Ciudad Universitaria, 5000 Cordoba (Argentina); Quiroga, A. [Centro de Investigacion y Estudios de Matematica / CONICET, Oficina 318 FaMAF - UNC, Ciudad Universitaria, 5000 Cordoba (Argentina); Valente, M., E-mail: fmattea@gmail.com [Instituto de Fisica E. Gaviola / CONICET, LIIFAMIRx, Oficina 102 FaMAF - UNC, 5000 Cordoba (Argentina)

    2014-08-15

    Polymer gel dosimeters have specific advantages for recording 3D radiation dose distribution representing a key factor for most of the therapeutic and diagnostic radiation techniques. Radiation-induced polymerization and crosslinking reactions that take place in the dosimeter have been studied for different monomers like acrylamide and N,N-methylene-bis acrylamide (Bis) and most recently for less toxic monomers like N-isopropylacrylamide and Bis. In this work a novel system based on itaconic acid and Bis is proposed, the radical polymerization or gel formation of these monomers has been already studied for the formation of an hydrogel for non dosimetric applications and their reactivity are comparable with the already mentioned systems. Although the 3D structure is maintained after the dosimeter has been irradiated, it is not possible to eliminate the diffusion of the reacted and monomer species in regions of dose gradients within the gel after irradiation. As a consequence the dose information of the dosimeters loose quality over time. The mobility within the gelatin structure of the already mentioned species is related to their chemical structure, and nature. In this work the effect of changes in the chemical structure of the monomers over the dosimetric sensitivity and over the post-irradiation diffusion of species is studied. One of the acrylic acid groups of the itaconic acid molecule is modified to obtain molecules with similar reactivity but different molecular sizes. Dosimetric systems with these modified species, Bis, an antioxidant to avoid oxygen polymerization inhibition, water and gelatin are irradiated in an X-ray tomography at different doses, and the resulting dosimeters are characterized by Raman spectroscopy and optical absorbance to study their feasibility and capabilities as dosimetric systems, and by optical-CT to analyze the diffusion degree after being irradiated. (Author)

  8. Dye-sensitized solar cells assembled with composite gel polymer electrolytes containing nanosized Al2O3 particles.

    Science.gov (United States)

    Jeon, Nawon; Kim, Dong-Won

    2013-12-01

    Polymeric ionic liquid, poly(1-methyl 3-(2-acryloyloxy propyl) imidazolium iodide) (PMAPII) containing iodide ions is synthesized and used as a matrix polymer for preparing the composite polymer electrolytes. The composite gel polymer electrolytes are prepared by utilizing PMAPII, organic solvent containing redox couple and aluminum oxide nanoparticle for application in dye-sensitized solar cells (DSSCs). PMAPII is highly compatible with organic solvents and thus there is no phase separation between the PMAPII and organic solvents. This makes it be possible to directly solidify the liquid electrolyte in the cell and maintain good interfacial contacts between the electrolyte and electrodes. The addition of 10 wt.% Al2O3 nanoparticle to gel polymer electrolyte provides the most desirable environment for ionic transport, resulting in the improvement of the photovoltaic performance of DSSC. The quasi-solid-state DSSC assembled with optimized composite gel polymer electrolyte containing 10 wt.% Al2O3 nanoparticle exhibits a relatively high conversion efficiency of 6.51% under AM 1.5 illumination at 100 mA cm(-2) and better stability than DSSC with liquid electrolyte.

  9. Conducting-polymer-driven actively shaped propellers and screws

    Science.gov (United States)

    Madden, John D.; Schmid, Bryan; Lafontaine, Serge R.; Madden, Peter G. A.; Hover, Franz S.; McLetchie, Karl; Hunter, Ian W.

    2003-07-01

    Conducting polymer actuators are employed to create actively shaped hydrodynamic foils. The active foils are designed to allow control over camber, much like the ailerons of an airplane wing. Control of camber promises to enable variable thrust in propellers and screws, increased maneuverability, and improved stealth. The design and fabrication of the active foils are presented, the forces are measured and operation is demonstrated both in still air and water. The foils have a "wing" span of 240 mm, and an average chord length (width) of 70 mm. The trailing 30 mm of the foil is composed of a thin polypyrrole actuator that curls chordwise to achieve variable camber. The actuator consists of two 30 μm thick sheets of hexafluorophosphate doped polypyrrole separated from each other by a gel electrolyte. A polymer layer encapsulates the entire structure. Potentials are applied between the polymer layers to induce reversible bending by approximately 35 degrees, and generating forces of 0.15 N. These forces and displacements are expected to enable operation in water at flow rates of > 1 m/s and ~ 30 m/s in air.

  10. Ionic liquid-polymer gel electrolytes based on morpholinium salt and PVdF(HFP) copolymer

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki-Sub; Park, Seung-Yeob; Choi, Sukjeong; Lee, Huen [Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

    2006-04-21

    New ionic liquid-polymer gel electrolytes (IPGEs) are prepared from N-ethyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide (Mor{sub 1,2}TFSI) and poly(vinylidene fluoride)-hexafluoropropylene copolymer (PVdF(HFP)). To investigate the effect of propylene carbonate (PC) on the ionic conductivity of the IPGEs, the preparation methods are roughly divided into two groups according to the presence or absence of PC. The ionic conductivity for each IPGE is measured with increasing temperature and changing weight ratio of Mor{sub 1,2}TFSI. The results show that the ionic conductivity increases as the temperature and weight ratio of the Mor{sub 1,2}TFSI increase, and that the added PC improves the ionic conductivity of the IPGEs. In addition, thermogravimetric analysis and the data from infrared spectroscopy demonstrate the thermal stability of each IPGE and the presence of PC in the polymer network. Although the IPGEs that contain PC display high conductivity ({approx}1.1x10{sup -2}Scm{sup -1}) at 60{sup o}C, they are thermally unstable. (author)

  11. Sol-gel molecularly imprinted polymer for selective solid phase microextraction of organophosphorous pesticides.

    Science.gov (United States)

    Wang, Yu-Long; Gao, Yuan-Li; Wang, Pei-Pei; Shang, Huan; Pan, Si-Yi; Li, Xiu-Juan

    2013-10-15

    A sol-gel technique was applied for the preparation of water-compatible molecularly imprinted polymer (MIP) for solid phase microextraction (SPME) using diazinon as template and polyethylene glycol as functional monomer. The MIP-coated fiber demonstrated much better selectivity to diazinon and its structural analogs in aqueous cucumber sample than in distilled water, indicating its potential in real samples. Thanks to its specific adsorption as well as rough and porous surface, the coating revealed rather larger extraction capability than the non-imprinted polymer and commercial fibers. In addition, the fiber exhibited excellent thermal (about 350°C) and chemical stability (organic and inorganic). After optimization of several parameters affecting extraction efficiency, a method based on MIP-SPME combined with gas chromatography was developed for the determination of organophosphorus pesticides (OPPs) in vegetable samples. The limits of detection for the tested OPPs were in the range of 0.017-0.77 μg kg(-1). The proposed method was applied to evaluate OPPs in spiked cucumber, green pepper, Chinese cabbage, eggplant and lettuce samples, and recoveries of 81.2-113.5% were obtained by the standard addition method with three spiking levels in each kind of vegetable.

  12. Gel Polymer Electrolytes Containing Anion-Trapping Boron Moieties for Lithium-Ion Battery Applications.

    Science.gov (United States)

    Shim, Jimin; Lee, Ji Su; Lee, Jin Hong; Kim, Hee Joong; Lee, Jong-Chan

    2016-10-04

    Gel polymer electrolytes (GPEs) based on semi-interpenetrating polymer network (IPN) structure for lithium-ion batteries were prepared by mixing boron-containing crosslinker (BC) composed of ion-conducting ethylene oxide (EO) chains, crosslinkable methacrylate group, and anion-trapping boron moiety with poly(vinylidene fluoride) (PVDF) followed by ultraviolet light-induced curing process. Various physical and electrochemical properties of the GPEs were systematically investigated by varying the EO chain length and boron content. Dimensional stability at high temperature without thermal shrinkage, if any, was observed due to the presence of thermally stable PVDF in the GPEs. GPE having 80 wt% of BC and 20 wt% of PVDF exhibited an ionic conductivity of 4.2 mS cm(-1) at 30 (o)C which is one order of magnitude larger than that of the liquid electrolyte system containing the commercial Celgard separator (0.4 mS cm(-1)) owing to the facile electrolyte uptake ability of EO chain and anion-trapping ability of boron moiety. As a result, lithium-ion battery cell prepared using the GPE with BC showed an excellent cycle performance at 1.0 C maintaining 87 % of capacity during 100 cycles.

  13. Dye-sensitized solar cell with natural gel polymer electrolytes and f-MWCNT as counter-electrode

    Science.gov (United States)

    Nwanya, A. C.; Amaechi, C. I.; Ekwealor, A. B. C.; Osuji, R. U.; Maaza, M.; Ezema, F. I.

    2015-05-01

    Samples of DSSCs were made with gel polymer electrolytes using agar, gelatin and DNA as the polymer hosts. Anthocyanine dye from Hildegardia barteri flower is used to sensitize the TiO2 electrode, and the spectrum of the dye indicates strong absorptions in the blue region of the solar spectrum. The XRD pattern of the TiO2 shows that the adsorption of the dye did not affect the crystallinity of the electrode. The f-MWCNT indicates graphite structure of the MWCNTs were acid oxidized without significant damage. Efficiencies of 3.38 and 0.1% were obtained using gelatin and DNA gel polymer electrolytes, respectively, for the fabricated dye-sensitized solar cells.

  14. Open-circuit voltage enhancement on the basis of polymer gel electrolyte for a highly stable dye-sensitized solar cell.

    Science.gov (United States)

    Wu, Congcong; Jia, Lichao; Guo, Siyao; Han, Song; Chi, Bo; Pu, Jian; Jian, Li

    2013-08-28

    Dye-sensitized solar cells (DSSC) have received considerable attention owing to their low preparation cost and easy fabrication process. However, one of the drawbacks that limits the further application of DSSC is their poor stability, arising from the leakage and volatilization of the liquid organic solvent in the electrolyte. Therefore, to improve the long-term stability of DSSC, polymer gel electrolyte was studied to replace the conventional liquid electrolyte in this work. The results show that compared to liquid electrolyte, DSSC with polymer gel electrolyte has a smaller short-circuit current (Jsc), which decreases with the increase of the polymer gelator. Nevertheless, with the employment of the polymer gel electrolyte, there is a significant enhancement of open-circuit voltage (Voc), and it increases with the increase of the polymer gelator content. The highest Voc, up to 0.873 V, can be obtained for DSSC with a 30% polymer gelator content. The impact of the polymer gel electrolyte on the photovoltaic performance of DSSC, especially on Voc, was studied by analyzing the charge-transfer kinetics in the polymer gel electrolyte. Furthermore, the influence of the polymer gel electrolyte on the long-term stability of DSSC was also investigated.

  15. Integration of active and passive polymer optics

    DEFF Research Database (Denmark)

    Christiansen, Mads Brøkner; Schøler, Mikkel; Kristensen, Anders

    2007-01-01

    protrusions and an integrated metal shadow mask. In the CNP process, a combined UV mask and nanoimprint stamp is embossed into the resist, which is softened by heating, and UV exposed. Hereby the mm to m m sized features are defined by the UV exposure through the metal mask, while nm-scale features are formed......We demonstrate a wafer scale fabrication process for integration of active and passive polymer optics: Polymer DFB lasers and waveguides. Polymer dye DFB lasers are fabricated by combined nanoimprint and photolithography (CNP). The CNP fabrication relies on an UV transparent stamp with nm sized...... by mechanical deformation (nanoimprinting). The lasers are integrated with undoped SU-8 polymer waveguides. The waferscale fabrication process has a yield above 90% and the emission wavelengths are reproduced within 2 nm. Confinement of the light on the chip is demonstrated, and the influence on the laser...

  16. Hierarchical Sol-Gel Transition Induced by Thermosensitive Self-Assembly of an ABC Triblock Polymer in an Ionic Liquid

    Energy Technology Data Exchange (ETDEWEB)

    Kitazawa, Yuzo; Ueki, Takeshi; McIntosh, Lucas D.; Tamura, Saki; Niitsuma, Kazuyuki; Imaizumi, Satoru; Lodge, Timothy P.; Watanabe, Masayoshi (U of Tokyo); (UMM); (Yokohama)

    2016-04-29

    Here we investigate a hierarchical morphology change and accompanying sol–gel transition using a doubly thermosensitive ABC-triblock copolymer in an ionic liquid (IL). The triblock copolymer contains two different lower critical solution temperature (LCST) thermosensitive polymers, poly(benzyl methacrylate) (PBnMA) and poly(2-phenylethyl methacrylate) (PPhEtMA), as the end blocks and poly(methyl methacrylate) (PMMA) as the middle block (PBnMA-b-PMMA-b-PPhEtMA: BMP). BMP undergoes a hierarchical phase transition corresponding to the self-assembly of each of the thermosensitive blocks in the IL, and a sol–gel transition was observed in concentrated, above 10 wt %, polymer solutions. The gelation behavior was affected by polymer concentration, and at 20 wt %, the BMP/IL composite showed a phase transition, with increasing temperature, from solution through a jammed micelle suspension to a physically cross-linked gel. For each phase was formed reversibly and rapidly over the corresponding temperature range. Finally, the jammed micelle and cross-linked gel states were characterized using viscoelastic measurements and small-angle X-ray scattering (SAXS).

  17. Evaluation of the Effects of Inhomogeneities on Dose Profiles Using Polymer Gel Dosimeter and Monte Carlo Simulation in Gamma Knife

    Directory of Open Access Journals (Sweden)

    Tayeb Allahverdi Pourfallah

    2012-03-01

    Full Text Available Introduction Polymer gel dosimeters offer a practical solution to 3D dose verification for conventional radiotherapy as well as intensity-modulated and stereotactic radiotherapy. In this study, EGSnrc calculated and PAGAT polymer gel dosimeter measured dose profiles from single shot irradiation with 18 mm collimator of Gamma Knife in homogeneous and inhomogeneous phantoms were compared with each other. Materials and Methods The head phantom was a custom-built 16 cm diameter plexiglas sphere. Inside the phantom, there were two cubic cutouts for inserting the gel vials and inhomogeneities. Following irradiation with the Gamma Knife unit, the polymer gel dosimeters were scanned with a 1.5 T MRI scanner. For the purpose of simulation the simplified channel of 60Co source of Gamma Knife BEAMnrc and for extracting the 3D dose distribution in the phantom, DOSXYZnrc codes were used. Results Within high isodose levels (>80%, there are dose differences higher than 7%, especially between air inserted and PTFE inserted phantoms, which were obtained using both simulation and experiment. This means that these values exceed the acceptance criterion of conformal radiotherapy and stereotactic radiosurgery (i.e., within some isodose levels, less than 93% of prescription dose are delivered to the target. Conclusion The discrepancies observed between the results obtained from heterogeneous and homogeneous phantoms suggest that Leksell Gamma Knife planning system (LGP predictions which assume the target as a homogeneous material must be corrected in order to take care of the air- and bone-tissue inhomogeneities.

  18. Development and manufacture of printable next-generation gel polymer ionic liquid electrolyte for Zn/MnO2 batteries

    Science.gov (United States)

    Winslow, R.; Wu, C. H.; Wang, Z.; Kim, B.; Keif, M.; Evans, J.; Wright, P.

    2013-12-01

    While much energy storage research focuses on the performance of individual components, such as the electrolyte or a single electrode, few investigate the electrochemical system as a whole. This research reports on the design, composition, and performance of a Zn/MnO2 battery as affected by the manufacturing method and next-generation gel polymer electrolyte composed of the ionic liquid [BMIM][Otf], ZnOtf salt, and PVDF-HFP polymer binder. Materials and manufacturing tests are discussed with a focus on water concentration, surface features as produced by printing processes, and the effect of including a gel polymer phase. Cells produced for this research generated open circuit voltages from 1.0 to 1.3 V. A dry [BMIM][Otf] electrolyte was found to have 87.3 ppm of H2O, while an electrolyte produced in ambient conditions contained 12400 ppm of H2O. Cells produced in a dry, Ar environment had an average discharge capacity of 0.0137 mAh/cm2, while one produced in an ambient environment exhibited a discharge capacity at 0.05 mAh/cm2. Surface features varied significantly by printing method, where a doctor blade produced the most consistent features. The preliminary results herein suggest that water, surface roughness, and the gel polymer play important roles in affecting the performance of printed energy storage.

  19. Boundaries steer the contraction of active gels

    Science.gov (United States)

    Schuppler, Matthias; Keber, Felix C.; Kröger, Martin; Bausch, Andreas R.

    2016-01-01

    Cells set up contractile actin arrays to drive various shape changes and to exert forces to their environment. To understand their assembly process, we present here a reconstituted contractile system, comprising F-actin and myosin II filaments, where we can control the local activation of myosin by light. By stimulating different symmetries, we show that the force balancing at the boundaries determine the shape changes as well as the dynamics of the global contraction. Spatially anisotropic attachment of initially isotropic networks leads to a self-organization of highly aligned contractile fibres, being reminiscent of the order formation in muscles or stress fibres. The observed shape changes and dynamics are fully recovered by a minimal physical model. PMID:27739426

  20. Boundaries steer the contraction of active gels

    Science.gov (United States)

    Schuppler, Matthias; Keber, Felix C.; Kröger, Martin; Bausch, Andreas R.

    2016-10-01

    Cells set up contractile actin arrays to drive various shape changes and to exert forces to their environment. To understand their assembly process, we present here a reconstituted contractile system, comprising F-actin and myosin II filaments, where we can control the local activation of myosin by light. By stimulating different symmetries, we show that the force balancing at the boundaries determine the shape changes as well as the dynamics of the global contraction. Spatially anisotropic attachment of initially isotropic networks leads to a self-organization of highly aligned contractile fibres, being reminiscent of the order formation in muscles or stress fibres. The observed shape changes and dynamics are fully recovered by a minimal physical model.

  1. Novel configuration of poly(vinylidenedifluoride)-based gel polymer electrolyte for application in lithium-ion batteries

    Science.gov (United States)

    Fasciani, Chiara; Panero, Stefania; Hassoun, Jusef; Scrosati, Bruno

    2015-10-01

    Herein we propose a novel poly(vinylidene difluoride) (PVdF)-based gel polymer electrolyte (GPE) for application in lithium-ion batteries, LIBs. The GPE is prepared under air as a dry, flexible film and directly gelled during LIB assembly with a conventional liquid organic electrolyte. The dry-gel here originally reported maintains its structural integrity due to the presence of crystallized EC-solvent within its matrix that avoids structural collapse, as demonstrated by TGA analysis. By avoiding the use of controlled atmosphere, the GPE is easy to handle and suitable for roll-to-roll scaling-up, i.e. characteristics missed by the common gel membranes. Scanning Electron Microscopy (SEM) evidences a micrometric polymer network of the dry membrane precursor acting as the support matrix for the gelation. Electrochemical impedance spectroscopy (EIS) measurements and galvanostatic tests suggest a good stability of the lithium electrode/gel electrolyte interface and a satisfactory lithium transference number. Cycling tests of gel-electrolyte-based lithium half-cells using lithium iron phosphate (LiFePO4, LFP) and graphite (C), respectively, as counter electrodes, as well as of a full C/LFP lithium-ion battery confirm the suitability of the GPE developed in this work for application in stable, low cost and environmentally friendly energy storage systems.

  2. Final Technical Report for 'Investigations of the Role of Protozoa in Transformations of Marine Biopolymers using Phaeocytis Polymer Gels as a Model'

    Energy Technology Data Exchange (ETDEWEB)

    Lessard, Evelyn

    2003-04-01

    OAK B188 Biopolymers and biopolymer gels are major components of the organic carbon and nitrogen pools in the ocean. The overall goal of this project was to better understand the chemical and physical transformations of polymers and polymer gels in coastal waters that are mediated by protists and bacteria. Bacteria are thought to be the major consumers of marine biopolymers, but direct consumption by protists, and the interactions of bacteria and protists, may also be important but largely unexplored pathways of biopolymer cycling. Phaeocystis is a colonial prymnesiophyte alga that produces large amounts of polymer gels that have similar properties to those found in the dissolved organic carbon (DOC) pool namely, they are tangled networks of polymers held together by calcium bridges. We used the polymers and polymer gels produced by two species of Phaeocystis (from the North Atlantic and Antarctica) as models to examine the consumption, degradation and alteration of algal polymer gels by protists and bacteria. We developed several novel methods and approaches to examine polymer gel transformations. One tool was an immunoassay (ELISA) using a polyclonal antibody specific to Phaeocystis polymers that allowed us to track the polymer gels in situ and in laboratory experiments. We successfully tested the ability of the immunoassay to detect and quantify Phaeocystis polymer carbon in water from the Ross Sea, Gulf of Alaska and North Water (Greenland). This exciting new approach demonstrates the usefulness of antibodies for detecting and quantifying a specific component of the DOM pool in natural samples and provides a method for following the sources and sinks of that component. We also developed a fluorescent immunoassay procedure with the antibody to visualize and quantify ingested polymers in single protist cells. In experiments with polymer gels as the sole organic source (no prey), prey plus polymer gels, and prey without polymer gels, we determined that some

  3. Gel polymer electrolyte lithium-ion cells with improved low temperature performance

    Science.gov (United States)

    Smart, M. C.; Ratnakumar, B. V.; Behar, A.; Whitcanack, L. D.; Yu, J.-S.; Alamgir, M.

    For a number of NASA's future planetary and terrestrial applications, high energy density rechargeable lithium batteries that can operate at very low temperature are desired. In the pursuit of developing Li-ion batteries with improved low temperature performance, we have also focused on assessing the viability of using gel polymer systems, due to their desirable form factor and enhanced safety characteristics. In the present study we have evaluated three classes of promising liquid low-temperature electrolytes that have been impregnated into gel polymer electrolyte carbon-LiMn 2O 4-based Li-ion cells (manufactured by LG Chem. Inc.), consisting of: (a) binary EC + EMC mixtures with very low EC-content (10%), (b) quaternary carbonate mixtures with low EC-content (16-20%), and (c) ternary electrolytes with very low EC-content (10%) and high proportions of ester co-solvents (i.e., 80%). These electrolytes have been compared with a baseline formulation (i.e., 1.0 M LiPF 6 in EC + DEC + DMC (1:1:1%, v/v/v), where EC, ethylene carbonate, DEC, diethyl carbonate, and DMC, dimethyl carbonate). We have performed a number of characterization tests on these cells, including: determining the rate capacity as a function of temperature (with preceding charge at room temperature and also at low temperature), the cycle life performance (both 100% DOD and 30% DOD low earth orbit cycling), the pulse capability, and the impedance characteristics at different temperatures. We have obtained excellent performance at low temperatures with ester-based electrolytes, including the demonstration of >80% of the room temperature capacity at -60 °C using a C/20 discharge rate with cells containing 1.0 M LiPF 6 in EC + EMC + MB (1:1:8%, v/v/v) (MB, methyl butyrate) and 1.0 M LiPF 6 in EC + EMC + EB (1:1:8%, v/v/v) (EB, ethyl butyrate) electrolytes. In addition, cells containing the ester-based electrolytes were observed to support 5 C pulses at -40 °C, while still maintaining a voltage >2.5 V at

  4. Three-Dimensional Nanoporous Cellulose Gels as a Flexible Reinforcement Matrix for Polymer Nanocomposites.

    Science.gov (United States)

    Shi, Zhuqun; Huang, Junchao; Liu, Chuanjun; Ding, Beibei; Kuga, Shigenori; Cai, Jie; Zhang, Lina

    2015-10-21

    With the world's focus on utilization of sustainable natural resources, the conversion of wood and plant fibers into cellulose nanowhiskers/nanofibers is essential for application of cellulose in polymer nanocomposites. Here, we present a novel fabrication method of polymer nanocomposites by in-situ polymerization of monomers in three-dimensionally nanoporous cellulose gels (NCG) prepared from aqueous alkali hydroxide/urea solution. The NCG have interconnected nanofibrillar cellulose network structure, resulting in high mechanical strength and size stability. Polymerization of the monomer gave P(MMA/BMA)/NCG, P(MMA/BA)/NCG nanocomposites with a volume fraction of NCG ranging from 15% to 78%. SEM, TEM, and XRD analyses show that the NCG are finely distributed and preserved well in the nanocomposites after polymerization. DMA analysis demonstrates a significant improvement in tensile storage modulus E' above the glass transition temperature; for instance, at 95 °C, E' is increased by over 4 orders of magnitude from 0.03 MPa of the P(MMA/BMA) up to 350 MPa of nanocomposites containing 15% v/v NCG. This reinforcement effect can be explained by the percolation model. The nanocomposites also show remarkable improvement in solvent resistance (swelling ratio of 1.3-2.2 in chloroform, acetone, and toluene), thermal stability (do not melt or decompose up to 300 °C), and low coefficients of thermal expansion (in-plane CTE of 15 ppm·K(-1)). These nanocomposites will have great promising applications in flexible display, packing, biomedical implants, and many others.

  5. SEM, XRD and electrical conductivity studies of PVDF-HFP-LiBF4 -EC plasticized gel polymer electrolyte

    Science.gov (United States)

    Sangeetha, M.; Mallikarjun, A.; Jaipal Reddy, M.; Siva Kumar, J.

    2017-07-01

    Micro porous gel type polymer electrolytes composed of 80 Wt% PVDF-HFP polymer - 20 Wt% LiBF4 salt in different concentrations of EC plasticizer (10Wt% - 70 Wt %) plasticizer have been synthesized by Solution cast technique. The effect of plasticizer in polymer-salt matrix, structural, morphological and ionic conductivity is studied. Structural and morphological studies showed increase in amorphous nature and recrystallization after a certain limit of EC plasticizer. The highest ionic conductivity of 1.510 × 10-3 Cm-1 is found for 40 Wt% of EC plasticizer at 303K. Addition of plasticizer increase free volume enables segmental motion of polymer and free mobility of ions. Also it provides more number of charge carriers in turn enhances the ionic conductivity up to certain limit of 40 Wt% of EC plasticizer. Further increase of plasticizer content creates ion-pair aggregation and recrystallization which reduces the ionic conductivity. The ionic conductivity obeys the VTF relationship for Gel type polymer electrolyte system.

  6. Stabilizing the Performance of High-Capacity Sulfur Composite Electrodes by a New Gel Polymer Electrolyte Configuration.

    Science.gov (United States)

    Agostini, Marco; Lim, Du Hyun; Sadd, Matthew; Fasciani, Chiara; Navarra, Maria Assunta; Panero, Stefania; Brutti, Sergio; Matic, Aleksandar; Scrosati, Bruno

    2017-09-11

    Increased pollution and the resulting increase in global warming are drawing attention to boosting the use of renewable energy sources such as solar or wind. However, the production of energy from most renewable sources is intermittent and thus relies on the availability of electrical energy-storage systems with high capacity and at competitive cost. Lithium-sulfur batteries are among the most promising technologies in this respect due to a very high theoretical energy density (1675 mAh g(-1) ) and that the active material, sulfur, is abundant and inexpensive. However, a so far limited practical energy density, life time, and the scaleup of materials and production processes prevent their introduction into commercial applications. In this work, we report on a simple strategy to address these issues by using a new gel polymer electrolyte (GPE) that enables stable performance close to the theoretical capacity of a low cost sulfur-carbon composite with high loading of active material, that is, 70 % sulfur. We show that the GPE prevents sulfur dissolution and reduces migration of polysulfide species to the anode. This functional mechanism of the GPE membranes is revealed by investigating both its morphology and the Li-anode/GPE interface at various states of discharge/charge using Raman spectroscopy. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Nylon-3 polymers with selective antifungal activity.

    Science.gov (United States)

    Liu, Runhui; Chen, Xinyu; Hayouka, Zvi; Chakraborty, Saswata; Falk, Shaun P; Weisblum, Bernard; Masters, Kristyn S; Gellman, Samuel H

    2013-04-10

    Host-defense peptides inhibit bacterial growth but show little toxicity toward mammalian cells. A variety of synthetic polymers have been reported to mimic this antibacterial selectivity; however, achieving comparable selectivity for fungi is more difficult because these pathogens are eukaryotes. Here we report nylon-3 polymers based on a novel subunit that display potent antifungal activity (MIC = 3.1 μg/mL for Candida albicans ) and favorable selectivity (IC10 > 400 μg/mL for 3T3 fibroblast toxicity; HC10 > 400 μg/mL for hemolysis).

  8. Hydroxypropyl Cellulose Based Non-Volatile Gel Polymer Electrolytes for Dye-Sensitized Solar Cell Applications using 1-methyl-3-propylimidazolium iodide ionic liquid

    Science.gov (United States)

    Khanmirzaei, Mohammad Hassan; Ramesh, S.; Ramesh, K.

    2015-12-01

    Gel polymer electrolytes using imidazolium based ionic liquids have attracted much attention in dye-sensitized solar cell applications. Hydroxypropyl cellulose (HPC), sodium iodide (NaI), 1-methyl-3-propylimidazolium iodide (MPII) as ionic liquid (IL), ethylene carbonate (EC) and propylene carbonate (PC) are used for preparation of non-volatile gel polymer electrolyte (GPE) system (HPC:EC:PC:NaI:MPII) for dye-sensitized solar cell (DSSC) applications. The highest ionic conductivity of 7.37 × 10-3 S cm-1 is achieved after introducing 100% of MPII with respect to the weight of HPC. Temperature-dependent ionic conductivity of gel polymer electrolytes is studied in this work. XRD patterns of gel polymer electrolytes are studied to confirm complexation between HPC polymer, NaI and MPII. Thermal behavior of the GPEs is studied using simultaneous thermal analyzer (STA) and differential scanning calorimetry (DSC). DSSCs are fabricated using gel polymer electrolytes and J-V centeracteristics of fabricated dye sensitized solar cells were analyzed. The gel polymer electrolyte with 100 wt.% of MPII ionic liquid shows the best performance and energy conversion efficiency of 5.79%, with short-circuit current density, open-circuit voltage and fill factor of 13.73 mA cm-2, 610 mV and 69.1%, respectively.

  9. Hydroxypropyl Cellulose Based Non-Volatile Gel Polymer Electrolytes for Dye-Sensitized Solar Cell Applications using 1-methyl-3-propylimidazolium iodide ionic liquid.

    Science.gov (United States)

    Khanmirzaei, Mohammad Hassan; Ramesh, S; Ramesh, K

    2015-12-11

    Gel polymer electrolytes using imidazolium based ionic liquids have attracted much attention in dye-sensitized solar cell applications. Hydroxypropyl cellulose (HPC), sodium iodide (NaI), 1-methyl-3-propylimidazolium iodide (MPII) as ionic liquid (IL), ethylene carbonate (EC) and propylene carbonate (PC) are used for preparation of non-volatile gel polymer electrolyte (GPE) system (HPC:EC:PC:NaI:MPII) for dye-sensitized solar cell (DSSC) applications. The highest ionic conductivity of 7.37 × 10(-3) S cm(-1) is achieved after introducing 100% of MPII with respect to the weight of HPC. Temperature-dependent ionic conductivity of gel polymer electrolytes is studied in this work. XRD patterns of gel polymer electrolytes are studied to confirm complexation between HPC polymer, NaI and MPII. Thermal behavior of the GPEs is studied using simultaneous thermal analyzer (STA) and differential scanning calorimetry (DSC). DSSCs are fabricated using gel polymer electrolytes and J-V centeracteristics of fabricated dye sensitized solar cells were analyzed. The gel polymer electrolyte with 100 wt.% of MPII ionic liquid shows the best performance and energy conversion efficiency of 5.79%, with short-circuit current density, open-circuit voltage and fill factor of 13.73 mA cm(-2), 610 mV and 69.1%, respectively.

  10. Rheological and DSC study of sol-gel transition in aqueous dispersions of industrially important polymers and colloids

    Energy Technology Data Exchange (ETDEWEB)

    Nishinari, K. [Osaka City Univ. (Japan). Dept. of Food and Nutrition

    1997-12-01

    Gelation kinetics, mechanical spectra, thermal scanning rheology (TSR), and differential scanning calorimetry (DSC) in aqueous solutions of gelling polymers and colloids such as seaweed polysaccharides (agarose, carrageenans), microbial polysaccharides (gellan, curdlan), plant polysaccharides (methylcellulose), globular proteins (casein, glycinin, {beta}-conglycinin), fibrous proteins (gelatin, fibrin), and polyvinyl alcohol, which are related to foods, cosmetics, biomedical and pharmaceutical applications, are described. Some gelation processes at a constant temperature have been treated successfully by an equation of first order kinetics or by other modified equations, and the molecular mechanism of gel formation is discussed briefly. For water-soluble polymers, the criterion of the gel or sol based on the frequency dependence of storage and loss moduli gives valuable informations. TSR and DSC are complementary, and the combination of these methods has been proved to be useful. (orig.) 81 refs.

  11. AC ionic conductivity and DC polarization method of lithium ion transport in PMMA-LiBF4 gel polymer electrolytes

    Science.gov (United States)

    Osman, Z.; Mohd Ghazali, M. I.; Othman, L.; Md Isa, K. B.

    2012-01-01

    Polymethylmethacrylate (PMMA)-based gel polymer electrolytes comprising ethylene carbonate-propylene carbonate (EC/PC) mixed solvent plasticizer and various concentrations of lithium tetrafluoroborate (LiBF4) salt are prepared using a solvent casting technique. Electrical conductivity and transference number measurements were carried out to investigate conductivity and charge transport in the gel polymer electrolytes. The conductivity results show that the ionic conductivity of the samples increases when the amount of salt is increased, however decreases after reaching the optimum value. This result is consistent with the transference number measurements. The conductivity-frequency dependence plots show two distinct regions; i.e. at lower frequencies the conductivity increases with increasing frequency and the frequency independent plateau region at higher frequencies. The temperature-dependence conductivity of the films seems to obey the Arrhenius rule.

  12. Ionic transport studies in PVDF-HFP-PMMA-(PC+DEC)-LiClO4 gel polymer electrolyte

    Science.gov (United States)

    Gohel, Khushbu; Kanchan, D. K.

    2017-05-01

    Poly(vinylidene fluoride-hexafluropropylene)(PVdF-HFP) and Polymethylmethacrylate(PMMA) based gel polymer electrolytes comprising Propylene Carbonate and Diethyl Carbonate mixed plasticizers and different concentrations of Lithium Perchlorate (LiClO4) salt have been prepared using a solvent casting technique. Electrical conductivity and transference number measurements have been carried out by Electrochemical Impedance Spectroscopy in the temperature range 303 K to 363 K and Wagner's Polarization method respectively. The maximum room temperature conductivity of 2.83 ×10-4 S cm-1 has been observed for the gel polymer electrolytes at 7.5 wt% LiClO4. The variation of ac conductivity with frequency has been discussed.

  13. Fast Switching Electrochromic Devices Containing Optimized BEMA/PEGMA Gel Polymer Electrolytes

    Directory of Open Access Journals (Sweden)

    N. Garino

    2013-01-01

    Full Text Available An optimized thermoset gel polymer electrolyte based on Bisphenol A ethoxylate dimethacrylate and Poly(ethylene glycol methyl ether methacrylate (BEMA/PEGMA was prepared by facile photo-induced free radical polymerisation technique and tested for the first time in electrochromic devices (ECD combining WO3 sputtered on ITO as cathodes and V2O5 electrodeposited on ITO as anodes. The behaviour of the prepared ECD was investigated electrochemically and electro-optically. The ECD transmission spectrum was monitored in the visible and near-infrared region by varying applied potential. A switching time of ca. 2 s for Li+ insertion (coloring and of ca. 1 s for Li+ de-insertion (bleaching were found. UV-VIS spectroelectrochemical measurements evidenced a considerable contrast between bleached and colored state along with a good stability over repeated cycles. The reported electrochromic devices showed a considerable enhancement of switching time with respect to the previously reported polymeric ECD indicating that they are good candidates for the implementation of intelligent windows and smart displays.

  14. Gel polymer electrolytes based on nanofibrous polyacrylonitrile–acrylate for lithium batteries

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dul-Sun [Department of Chemical and Biological Engineering, Research Institute for Green Energy Convergence Technology, Gyeongsang National University, 900 Gajwa-dong, Jinju 660-701 (Korea, Republic of); Woo, Jang Chang [Department of Textile Engineering, Inha University, 100 Inharo, Nam-gu Incheon 402-751 (Korea, Republic of); Youk, Ji Ho, E-mail: youk@inha.ac.kr [Department of Textile Engineering, Inha University, 100 Inharo, Nam-gu Incheon 402-751 (Korea, Republic of); Manuel, James [Department of Chemical and Biological Engineering, Research Institute for Green Energy Convergence Technology, Gyeongsang National University, 900 Gajwa-dong, Jinju 660-701 (Korea, Republic of); Ahn, Jou-Hyeon, E-mail: jhahn@gnu.ac.kr [Department of Chemical and Biological Engineering, Research Institute for Green Energy Convergence Technology, Gyeongsang National University, 900 Gajwa-dong, Jinju 660-701 (Korea, Republic of); Department of Materials Engineering and Convergence Technology, Gyeongsang National University, 900 Gajwa-dong, Jinju 660-701 (Korea, Republic of)

    2014-10-15

    Graphical abstract: - Highlights: • Nanofibrous polyacrylonitrile–acrylate membranes were prepared by electrospinning. • Trimethylolpropane triacrylate was used as a crosslinking agent of fibers. • The GPE based on PAN–acrylate (1/0.5) showed good electrochemical properties. - Abstract: Nanofibrous membranes for gel polymer electrolytes (GPEs) were prepared by electrospinning a mixture of polyacrylonitrile (PAN) and trimethylolpropane triacrylate (TMPTA) at weight ratios of 1/0.5 and 1/1. TMPTA is used to achieve crosslinking of fibers thereby improving mechanical strength. The average fiber diameters increased with increasing TMPTA concentration and the mechanical strength was also improved due to the enhanced crosslinking of fibers. GPEs based on electrospun membranes were prepared by soaking them in a liquid electrolyte of 1 M LiPF{sub 6} in ethylene carbonate (EC)/dimethyl carbonate (DMC) (1:1, v/v). The electrolyte uptake and ionic conductivity of GPEs based on PAN and PAN–acrylate (weight ratio; 1/1 and 1/0.5) were investigated. Ionic conductivity of GPEs based on PAN–acrylate was the highest for PAN/acrylate (1/0.5) due to the proper swelling of fibers and good affinity with liquid electrolyte. Both GPEs based on PAN and PAN–acrylate membranes show good oxidation stability, >5.0 V vs. Li/Li{sup +}. Cells with GPEs based on PAN–acrylate (1/0.5) showed remarkable cycle performance with high initial discharge capacity and low capacity fading.

  15. ZnTe Semiconductor-Polymer Gel Composited Electrolyte for Conversion of Solar Energy

    Directory of Open Access Journals (Sweden)

    Wonchai Promnopas

    2014-01-01

    Full Text Available Nanostructured cubic p-type ZnTe for dye sensitized solar cells (DSSCs was synthesized from 1 : 1 molar ratio of Zn : Te by 600 W and 900 W microwave plasma for 30 min. In this research, their green emissions were detected at the same wavelengths of 563 nm, the energy gap (Eg at 2.24 eV, and three Raman shifts at 205, 410, and 620 cm−1. The nanocomposited electrolyte of quasisolid state ZnO-DSSCs was in correlation with the increase in the JSC, VOC, fill factor (ff, and efficiency (η by increasing the wt% of ZnTe-GPE (gel polymer electrolyte to an optimum value and decreased afterwards. The optimal ZnO-DSSC performance was achieved for 0.20 wt% ZnTe-GPE with the highest photoelectronic energy conversion efficiency at 174.7% with respect to that of the GPE without doping of p-type ZnTe.

  16. Water-based thixotropic polymer gel electrolyte for dye-sensitized solar cells.

    Science.gov (United States)

    Park, Se Jeong; Yoo, Kichoen; Kim, Jae-Yup; Kim, Jin Young; Lee, Doh-Kwon; Kim, Bongsoo; Kim, Honggon; Kim, Jong Hak; Cho, Jinhan; Ko, Min Jae

    2013-05-28

    For the practical application of dye-sensitized solar cells (DSSCs), it is important to replace the conventional organic solvents based electrolyte with environmentally friendly and stable ones, due to the toxicity and leakage problems. Here we report a noble water-based thixotropic polymer gel electrolyte containing xanthan gum, which satisfies both the environmentally friendliness and stability against leakage and water intrusion. For application in DSSCs, it was possible to infiltrate the prepared electrolyte into the mesoporous TiO2 electrode at the fluidic state, resulting in sufficient penetration. As a result, this electrolyte exhibited similar conversion efficiency (4.78% at 100 mW cm(-2)) and an enhanced long-term stability compared to a water-based liquid electrolyte. The effects of water on the photovoltaic properties were examined elaborately from the cyclic voltammetry curves and impedance spectra. Despite the positive shift in the conduction band potential of the TiO2 electrode, the open-circuit voltage was enhanced by addition of water in the electrolyte due to the greater positive shift in the I(-)/I3(-) redox potential. However, due to the dye desorption and decreased diffusion coefficient caused by the water content, the short-circuit photocurrent density was reduced. These results will provide great insight into the development of efficient and stable water-based electrolytes.

  17. Three-dimensional dosimetry of TomoTherapy by MRI-based polymer gel technique.

    Science.gov (United States)

    Watanabe, Yoichi; Gopishankar, N

    2010-09-14

    Verification of the dose calculation model and the software used for treatment planning is an important step for accurate radiation delivery in radiation therapy. Using BANG3 polymer gel dosimeter with a 3 Tesla magnetic resonance imaging (MRI) scanner, we examined the accuracy of TomoTherapy treatment planning and radiation delivery. We evaluated one prostate treatment case and found the calculated three-dimensional (3D) dose distributions agree with the measured 3D dose distributions with an exception in the regions where the dose was much smaller (25% or less) than the maximum dose (2.5 Gy). The analysis using the gamma-index (3% dose difference and 3 mm distance-to-agreement) for a volume of 12 cm × 11 cm × 9 cm containing the planning target volume showed that the gamma values were smaller than unity for 53% of the voxels. Our measurement protocol and analysis tools can be easily applied to the evaluation of other newer complex radiation delivery techniques, such as intensity-modulated arc therapy, with a reasonably low financial investment.

  18. Interpenetrating Polymer Network Hydrogels Based on VP/MMA Gel and PLGA Diacrylate Macromers

    Science.gov (United States)

    Lee, J. Hannah; Radzi, Zamri; Swan, Marc; Bucknall, David; Czernuszka, Jan

    2010-03-01

    Hydrogels have been widely used in biomedical applications due to their biocompatibility, similar physical properties to human tissue and appropriate mechanical properties. A thorough understanding of their swelling behavior is necessary to be able to choose the most suitable hydrogel and to applying it optimally. The long term goal of our research is to develop hydrogel systems with controllable swelling behavior for medical/surgical use. For this purpose, interpenetrating polymer network (IPN) hydrogels have been prepared based on the N-vinyl-2-pyrrolidone (VP)/methyl methacrylate (MMA) copolymeric gel and poly(DL-lactic-co-glycolic acid) (PLGA) diacrylate macromers as well as semi-IPN VP/MMA and PLGA hydrogels. The thermal, morphological, mechanical and physical properties of the hydrogels have been characterized and the potential for surgical use verified. This presentation will concentrate on the studies of the swelling kinetics and equilibrium swelling ratios of the hydrogels. In addition, very recent results will be presented on how additions of PLGA can be used to manipulate the swelling behavior of the hydrogel system.

  19. Highly branched and loop-rich gels via formation of metal-organic cages linked by polymers.

    Science.gov (United States)

    Zhukhovitskiy, Aleksandr V; Zhong, Mingjiang; Keeler, Eric G; Michaelis, Vladimir K; Sun, Jessie E P; Hore, Michael J A; Pochan, Darrin J; Griffin, Robert G; Willard, Adam P; Johnson, Jeremiah A

    2016-01-01

    Gels formed via metal-ligand coordination typically have very low branch functionality, f, as they consist of ∼2-3 polymer chains linked to single metal ions that serve as junctions. Thus, these materials are very soft and unable to withstand network defects such as dangling ends and loops. We report here a new class of gels assembled from polymeric ligands and metal-organic cages (MOCs) as junctions. The resulting 'polyMOC' gels are precisely tunable and may feature increased branch functionality. We show two examples of such polyMOCs: a gel with a low f based on a M2L4 paddlewheel cluster junction and a compositionally isomeric one of higher f based on a M12L24 cage. The latter features large shear moduli, but also a very large number of elastically inactive loop defects that we subsequently exchanged for functional ligands, with no impact on the gel's shear modulus. Such a ligand substitution is not possible in gels of low f, including the M2L4-based polyMOC.

  20. Comparison of Energy Dependence of PAGAT Polymer Gel Dosimeter with Electron and Photon Beams using Magnetic Resonance Imaging

    Directory of Open Access Journals (Sweden)

    B. Azadbakht

    2012-02-01

    Full Text Available The purpose of this study was to evaluate dependence of PAGAT polymer gel dosimeter 1/T2 on different electron and photon energies for a standard clinically used 60Co therapy unit and an electa linear accelerator.Using MRI, the formulation to give the maximum change in the transverse relaxation rate R2(1/T2 was determined to be 4.5% N,N'-methylen-bis-acrylamide(bis, 4.5% acrylamid(AA, 5% gelatine, 5 mM tetrakis (hydroxymethyl phosphonium chloride (THPC, 0.01 mM hydroquinone (HQ and 86% HPLC(Water. When the preparation of final polymer gel solution is completed, it is transferred into phantoms and allowed to set by storage in a refrigerator at about 4°C. The optimal post-manufacture irradiation and post imaging times were both determined to be 24 h. The sensitivity of PAGAT polymer gel dosimeter with irradiation of photon and electron beams was represented by the slope of calibration curve in the linear region measured for each modality. The response of PAGAT gel with photon and electron beams is very similar in the lower dose region. The R2-dose response was linear up to 30 Gy and the R2-dose response of the PAGAT polymer gel dosimeter is linear between 10 to 30 Gy. In electron beams the R2-dose response for doses less than 3 Gy is not exact, but in photon beams the R2-dose response for doses less than 2Gy is not exact. Dosimeter energy dependence was studied for electron energies of 4, 12 and 18MeV and photon energies of 1.25, 4, 6 and 18 MV. Evaluation of dosimeters were performed on Siemens Symphony, Germany 1.5T Scanner in the head coil. In this study no trend in polymer-gel dosimeter 1/T2 dependence was found on mean energy for electron and photon beams.

  1. Tailoring Wettability Through the Surface Modification of Electro-spun Polymers by Plasma and Sol-gel Treatments

    Science.gov (United States)

    2014-11-01

    water repellency of electrospun materials, two polymers with different surface energies were used: polyurethane containing urethane and phenyl...study concluded that for water repellency , thin beaded fibres were superior to thicker non-beaded fibres if the bead density was sufficiently high and...hydrophobic due to the roughness imparted by electrospinning. Sol-gel coating increased the water repellency to superhydrophobic ranges, achieving contact

  2. Two distinct lithium diffusive species for polymer gel electrolytes containing LiBF₄, propylene carbonate (PC) and PVDF

    OpenAIRE

    Richardson, PM; Voice, AM; Ward, IM

    2014-01-01

    Polymer gel electrolytes have been prepared using lithium tetrafluoroborate (LiBF₄), propylene carbonate (PC) and polyvinylidene fluoride (PVDF) at 20% and 30% concentration by mass. Self diffusion coefficients have been measured using pulse field gradient nuclear magnetic resonance (PFG-NMR) for the cation and anion using ⁷Li and ¹⁹F resonant frequencies respectively. It was found that lithium ion diffusion was slow compared to the much larger fluorine anion likely resulting from a large sol...

  3. Anomalous discontinuity at the percolation critical point of active gels.

    Science.gov (United States)

    Sheinman, M; Sharma, A; Alvarado, J; Koenderink, G H; MacKintosh, F C

    2015-03-06

    We develop a percolation model motivated by recent experimental studies of gels with active network remodeling by molecular motors. This remodeling was found to lead to a critical state reminiscent of random percolation (RP), but with a cluster distribution inconsistent with RP. Our model not only can account for these experiments, but also exhibits an unusual type of mixed phase transition: We find that the transition is characterized by signatures of criticality, but with a discontinuity in the order parameter.

  4. Antibacterial Activity of Copaiba Oil Gel on Dental Biofilm

    OpenAIRE

    Simões, Cláudia A.C.G.; Conde, Nikeila C. de Oliveira; Venâncio, Gisely N.; Milério, Patrícia S.L.L.; Bandeira, Maria F.C.L.; da Veiga Júnior, Valdir F.

    2016-01-01

    Amazonian biodiversity products that have been used for years in folk medicine, have emerged as feasible and promising alternatives for the inhibition of microorganisms in dental biofilm. Copaiba oil, a phytotherapic agent widely used by the Amazonian populations, is known for its antibacterial, anti-inflammatory, anesthetic, healing and antitumor medicinal properties. Objective: The aim of this study was to evaluate the in vitro antibacterial activity of copaiba oil (Copaifera multijuga) gel...

  5. Tracer diffusion in a polymer gel: simulations of static and dynamic 3D networks using spherical boundary conditions

    Science.gov (United States)

    Kamerlin, Natasha; Elvingson, Christer

    2016-11-01

    We have investigated an alternative to the standard periodic boundary conditions for simulating the diffusion of tracer particles in a polymer gel by performing Brownian dynamics simulations using spherical boundary conditions. The gel network is constructed by randomly distributing tetravalent cross-linking nodes and connecting nearest pairs. The final gel structure is characterised by the radial distribution functions, chain lengths and end-to-end distances, and the pore size distribution. We have looked at the diffusion of tracer particles with a wide range of sizes, diffusing in both static and dynamic networks of two different volume fractions. It is quantitatively shown that the dynamical effect of the network becomes more important in facilitating the diffusional transport for larger particle sizes, and that one obtains a finite diffusion also for particle sizes well above the maximum in the pore size distribution.

  6. Electrochemical impedimetric sensor based on molecularly imprinted polymers/sol-gel chemistry for methidathion organophosphorous insecticide recognition.

    Science.gov (United States)

    Bakas, Idriss; Hayat, Akhtar; Piletsky, Sergey; Piletska, Elena; Chehimi, Mohamed M; Noguer, Thierry; Rouillon, Régis

    2014-12-01

    We report here a novel method to detect methidathion organophosphorous insecticides. The sensing platform was architected by the combination of molecularly imprinted polymers and sol-gel technique on inexpensive, portable and disposable screen printed carbon electrodes. Electrochemical impedimetric detection technique was employed to perform the label free detection of the target analyte on the designed MIP/sol-gel integrated platform. The selection of the target specific monomer by electrochemical impedimetric methods was consistent with the results obtained by the computational modelling method. The prepared electrochemical MIP/sol-gel based sensor exhibited a high recognition capability toward methidathion, as well as a broad linear range and a low detection limit under the optimized conditions. Satisfactory results were also obtained for the methidathion determination in waste water samples.

  7. Immobilization of activated sludge using improved polyvinyl alcohol (PVA) gel

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The microbial immobilization method using polyvinyl alcohol (PVA) gel as an immobilizing material was improved and used for entrapment of activated sludge. The OUR (oxygen uptake rate) was used to characterize the biological activity of immobilized activated sludge. Three kinds of PVA-immobilized particles of activated sludge, that is, PVA-boric acid beads, PVA-sodium nitrate beads and PVA-orthophosphate beads was prepared, and their biological activity was compared by measuring the OUR value. The bioactivity of both autotrophic and heterotrophic microorganisms of activated sludge was determined using different synthetic wastewater media (containing 250 mg/L COD and 25 mg/L NH4+-N). The experimental results showed that the bioactivity and stability of the three kinds of immobilized activated sludge was greatly improved after activation. With respect of the bioactivity and the mechanical stability, the PVA-orthophosphate method may be a promising and economical technique for microbial immobilization.

  8. Natural macromolecule based carboxymethyl cellulose as a gel polymer electrolyte with adjustable porosity for lithium ion batteries

    Science.gov (United States)

    Zhu, Y. S.; Xiao, S. Y.; Li, M. X.; Chang, Z.; Wang, F. X.; Gao, J.; Wu, Y. P.

    2015-08-01

    A porous membrane of carboxymethyl cellulose (CMC) from natural macromolecule as a host of a gel polymer electrolyte for lithium ion batteries is reported. It is prepared, for the first time, by a simple non-solvent evaporation method and its porous structure is fine-adjusted by varying the composition ratio of the solvent and non-solvent mixture. The electrolyte uptake of the porous membrane based on CMC is 75.9%. The ionic conductivity of the as-prepared gel membrane saturated with 1 mol L-1 LiPF6 electrolyte at room temperature can be up to 0.48 mS cm-1. Moreover, the lithium ion transference in the gel membrane at room temperature is as high as 0.46, much higher than 0.27 for the commercial separator Celgard 2730. When evaluated by using LiFePO4 cathode, the prepared gel membrane exhibits very good electrochemical performance including higher reversible capacity, better rate capability and good cycling behaviour. The obtained results suggest that this porous polymer membrane shows great attraction to the lithium ion batteries requiring high safety, low cost and environmental friendliness.

  9. Oxidation increases mucin polymer cross-links to stiffen airway mucus gels.

    Science.gov (United States)

    Yuan, Shaopeng; Hollinger, Martin; Lachowicz-Scroggins, Marrah E; Kerr, Sheena C; Dunican, Eleanor M; Daniel, Brian M; Ghosh, Sudakshina; Erzurum, Serpel C; Willard, Belinda; Hazen, Stanley L; Huang, Xiaozhu; Carrington, Stephen D; Oscarson, Stefan; Fahy, John V

    2015-02-25

    Airway mucus in cystic fibrosis (CF) is highly elastic, but the mechanism behind this pathology is unclear. We hypothesized that the biophysical properties of CF mucus are altered because of neutrophilic oxidative stress. Using confocal imaging, rheology, and biochemical measures of inflammation and oxidation, we found that CF airway mucus gels have a molecular architecture characterized by a core of mucin covered by a web of DNA and a rheological profile characterized by high elasticity that can be normalized by chemical reduction. We also found that high levels of reactive oxygen species in CF mucus correlated positively and significantly with high concentrations of the oxidized products of cysteine (disulfide cross-links). To directly determine whether oxidation can cross-link mucins to increase mucus elasticity, we exposed induced sputum from healthy subjects to oxidizing stimuli and found a marked and thiol-dependent increase in sputum elasticity. Targeting mucin disulfide cross-links using current thiol-amino structures such as N-acetylcysteine (NAC) requires high drug concentrations to have mucolytic effects. We therefore synthesized a thiol-carbohydrate structure (methyl 6-thio-6-deoxy-α-D-galactopyranoside) and found that it had stronger reducing activity than NAC and more potent and fast-acting mucolytic activity in CF sputum. Thus, oxidation arising from airway inflammation or environmental exposure contributes to pathologic mucus gel formation in the lung, which suggests that it can be targeted by thiol-modified carbohydrates.

  10. Preparation of porous, chemically cross-linked, PVdF-based gel polymer electrolytes for rechargeable lithium batteries

    Science.gov (United States)

    Cheng, C. L.; Wan, C. C.; Wang, Y. Y.

    This study reports the development of a new system of porous, chemically cross-linked, gel polymer electrolytes based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) copolymer as a polymer matrix, polyethylene glycol (PEG) as a plasticizer, and polyethylene glycol dimethacrylate (PEGDMA) as a chemical cross-linking oligomer. The electrolytes are prepared by a combination of controlled evaporation and thermal polymerization of PEGDMA. PVdF-HFP/PEG/PEGDMA gel polymer electrolytes with a composition of 5/3/2 exhibit both high ambient ionic conductivity, viz., >1 mS cm -1, and a high tensile modulus of 52 MPa, because of their porous and network structures. All the blends of electrolytes are electrochemically stable up to 5 V versus Li/Li + in the presence of 1 M LiPF 6/ethylene carbonate-diethyl carbonate (EC-DEC). With these polymer electrolytes, rechargeable lithium batteries composed of carbon anode and LiCoO 2 cathode have acceptable cycleability and a good rate capability.

  11. Polymer particles filled with multiple colloidal silica via in situ sol-gel process and their thermal property

    Science.gov (United States)

    Byun, Hongsik; Hu, Jiayun; Pakawanit, Phakkhananan; Srisombat, Laongnuan; Kim, Jun-Hyun

    2017-01-01

    The in situ formation of dielectric silica (SiO2) particles was carried out in the presence of temperature-responsive poly(N-isopropylacrylamide) particles. Unlike the typical sol-gel method used to prepare various SiO2 particles, the highly uniform growth of SiO2 particles was achieved within the cross-linked polymer particles (i.e., the polymer particles were filled with the SiO2 particles) simply by utilizing interfacial interactions, including the van der Waals attractive force and hydrogen bonding in nanoscale environments. The structural and morphological features as well as the thermal behaviors of these composites were thoroughly examined by electron microscopes, dynamic light scattering, and thermal analyzers. In particular, the thermal properties of these composites were completely different from the bare polymer, SiO2 particles, and their mixtures, which clearly suggested the successful incorporation of multiple SiO2 particles within the cross-linked polymer particles. Similarly, titanium oxide (TiO2) particles were easily embedded within the polymer particle template which exhibited improved overall properties. As a whole, understanding in situ formation of nanoscale inorganic particles within polymer particle templates can allow for designing novel composite materials possessing enhanced chemical and physical properties.

  12. Nano-composite polymer gel electrolytes containing ortho-nitro benzoic acid: role of dielectric constant of solvent and fumed silica

    Science.gov (United States)

    Kumar, R.

    2015-03-01

    In this paper, nano-composite polymer gel electrolytes containing polymethylmethacrylate, dimethylacetamide, diethyl carbonate, fumed silica and ortho-nitro benzoic acid have been synthesized. Electrical conductivity, viscosity, pH and thermal behavior of these electrolytes have been studied. The effect of acid, polymer, fumed silica concentration on conductivity, pH and viscosity has been discussed. The effect of dielectric constant of solvent on conductivity behavior of composite polymer gel electrolytes has also been studied. Two maxima in conductivity behavior have been observed with fumed silica concentration for composite polymer gel electrolytes, which have been explained on the basis of double percolation threshold model. Maximum conductivity of 3.20 × 10-4 and 2.46 × 10-6 S/cm at room temperature has been observed for nano-composite polymer gel electrolytes containing 10 wt% polymethylmethacrylate in 1 M solution of o-nitro benzoic acid in dimethylacetamide and diethyl carbonate respectively. The intensity of first maximum observed in conductivity at low concentration of fumed silica has been found to decrease with the decrease in acid concentration for composite polymer gel electrolytes, while the intensity of second maximum at higher fumed silica concentration remains unaffected. The conductivity of composite gels does not show much change in the temperature range of 20-100 °C and also remains constant with time, making them suitable for use as electrolytes in various devices like fuel cells, proton batteries, electrochromic window applications etc.

  13. Nanocrystalline nickel ferrite particles synthesized by non-hydrolytic sol-gel method and their composite with biodegradable polymer.

    Science.gov (United States)

    Yin, H; Casey, P S; Chow, G M

    2012-11-01

    Targeted drug delivery has been one of the most important biomedical applications for magnetic particles. Such applications require magnetic particles to have functionalized surfaces/surface coatings that facilitate their incorporation into a polymer matrix to produce a polymer composite. In this paper, nanocrystalline nickel ferrite particles with an oleic acid surface coating were synthesized using a non-hydrolytic sol-gel method and incorporated into a biodegradable polymer matrix, poly(D,L-lactide) PLA prepared using a double emulsion method. As-synthesized nickel ferrite particles had a multi-crystalline structure with chemically adsorbed oleic acid on their surface. After forming the PLA composite, nickel ferrite particles were encapsulated in PLA microspheres. At low nickel ferrite concentrations, composites showed very similar surface charges to that of PLA. The composites were magnetically responsive and increasing the nickel ferrite concentration was found to increase magnetization of the composite.

  14. Gelation Behavior Study of a Resorcinol–Hexamethyleneteramine Crosslinked Polymer Gel for Water Shut-Off Treatment in Low Temperature and High Salinity Reservoirs

    Directory of Open Access Journals (Sweden)

    Yongpeng Sun

    2017-07-01

    Full Text Available Mature oilfields usually encounter the problem of high watercut. It is practical to use chemical methods for water-shutoff in production wells, however conventional water-shutoff agents have problems of long gelation time, low gel strength, and poor stability under low temperature and high salinity conditions. In this work a novel polymer gel for low temperature and high salinity reservoirs was developed. This water-shutoff agent had controllable gelation time, adjustable gel strength and good stability performance. The crosslinking process of this polymer gel was studied by rheological experiments. The process could be divided into an induction period, a fast crosslinking period, and a stable period. Its gelation behaviors were investigated in detail. According to the Gel Strength Code (GSC and vacuum breakthrough method, the gel strength was displayed in contour maps. The composition of the polymer gel was optimized to 0.25~0.3% YG100 + 0.6~0.9% resorcinol + 0.2~0.4% hexamethylenetetramine (HMTA + 0.08~0.27% conditioner (oxalic acid. With the concentration increase of the polymer gel and temperature, the decrease of pH, the induction period became shorter and the crosslinking was more efficient, resulting in better stability performance. Various factors of the gelation behavior which have an impact on the crosslinking reaction process were examined. The relationships between each impact factor and the initial crosslinking time were described with mathematical equations.

  15. Adsorption characteristics, recognition properties, and preliminary application of nordihydroguaiaretic acid molecularly imprinted polymers prepared by sol–gel surface imprinting technology

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Sen; Zhang, Wen; Long, Wei; Hou, Dan; Yang, Xuechun; Tan, Ni, E-mail: tannii@21cn.com

    2016-02-28

    Graphical abstract: - Highlights: • Nordihydroguaiaretic acid imprinted polymer with imprinting factor 2.12 was prepared for the first time through hydrogen bonding and hydrophobic interaction between the template molecules and the bifunctional monomers. • The obtained surface molecularly imprinting polymers exhibited high affinity and selectivity to the template molecules. • The prepared surface molecularly imprinted polymers were used in separation the natural active component nordihydroguaiaretic acid from medicinal plants. - Abstract: In this paper, a new core-shell composite of nordihydroguaiaretic acid (NDGA) molecularly imprinted polymers layer-coated silica gel (MIP@SiO{sub 2}) was prepared through sol–gel technique and applied as a material for extraction of NDGA from Ephedra. It was synthesized using NDGA as the template molecule, γ-aminopropyltriethoxysilane (APTS) and methyltriethoxysilane (MTEOS) as the functional monomers, tetraethyl orthosilicate (TEOS) as the cross-linker and ethanol as the porogenic solvent in the surface of silica. The non-imprinted polymers layer-coated silica gel (NIP@SiO{sub 2}) were prepared with the same procedure, but with the absence of template molecule. In addition, the optimum adsorption affinity occurred when the molar ratio of NDGA:APTS:MTEOS:TEOS was 1:6:2:80. The prepared MIP@SiO{sub 2} and NIP@SiO{sub 2} were analyzed by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Fourier transform-infrared spectroscopy (FT-IR). Their affinity properties to NDGA were evaluated through dynamic adsorption, static adsorption, and selective recognition experiments, and the results showed the saturated adsorption capacity of MIP@SiO{sub 2} could reach to 5.90 mg g{sup −1}, which was two times more than that of NIP@SiO{sub 2}. High performance liquid chromatography (HPLC) was used to evaluate the extraction of NDGA from the medicinal plant ephedra by the above prepared materials, and the results

  16. A novel method of estimating dose responses for polymer gels using texture analysis of scanning electron microscopy images.

    Directory of Open Access Journals (Sweden)

    Cheng-Ting Shih

    Full Text Available Polymer gels are regarded as a potential dosimeter for independent validation of absorbed doses in clinical radiotherapy. Several imaging modalities have been used to convert radiation-induced polymerization to absorbed doses from a macro-scale viewpoint. This study developed a novel dose conversion mechanism by texture analysis of scanning electron microscopy (SEM images. The modified N-isopropyl-acrylamide (NIPAM gels were prepared under normoxic conditions, and were administered radiation doses from 5 to 20 Gy. After freeze drying, the gel samples were sliced for SEM scanning with 50×, 500×, and 3500× magnifications. Four texture indices were calculated based on the gray level co-occurrence matrix (GLCM. The results showed that entropy and homogeneity were more suitable than contrast and energy as dose indices for higher linearity and sensitivity of the dose response curves. After parameter optimization, an R (2 value of 0.993 can be achieved for homogeneity using 500× magnified SEM images with 27 pixel offsets and no outlier exclusion. For dose verification, the percentage errors between the prescribed dose and the measured dose for 5, 10, 15, and 20 Gy were -7.60%, 5.80%, 2.53%, and -0.95%, respectively. We conclude that texture analysis can be applied to the SEM images of gel dosimeters to accurately convert micro-scale structural features to absorbed doses. The proposed method may extend the feasibility of applying gel dosimeters in the fields of diagnostic radiology and radiation protection.

  17. A novel method of estimating dose responses for polymer gels using texture analysis of scanning electron microscopy images.

    Science.gov (United States)

    Shih, Cheng-Ting; Hsu, Jui-Ting; Han, Rou-Ping; Hsieh, Bor-Tsung; Chang, Shu-Jun; Wu, Jay

    2013-01-01

    Polymer gels are regarded as a potential dosimeter for independent validation of absorbed doses in clinical radiotherapy. Several imaging modalities have been used to convert radiation-induced polymerization to absorbed doses from a macro-scale viewpoint. This study developed a novel dose conversion mechanism by texture analysis of scanning electron microscopy (SEM) images. The modified N-isopropyl-acrylamide (NIPAM) gels were prepared under normoxic conditions, and were administered radiation doses from 5 to 20 Gy. After freeze drying, the gel samples were sliced for SEM scanning with 50×, 500×, and 3500× magnifications. Four texture indices were calculated based on the gray level co-occurrence matrix (GLCM). The results showed that entropy and homogeneity were more suitable than contrast and energy as dose indices for higher linearity and sensitivity of the dose response curves. After parameter optimization, an R (2) value of 0.993 can be achieved for homogeneity using 500× magnified SEM images with 27 pixel offsets and no outlier exclusion. For dose verification, the percentage errors between the prescribed dose and the measured dose for 5, 10, 15, and 20 Gy were -7.60%, 5.80%, 2.53%, and -0.95%, respectively. We conclude that texture analysis can be applied to the SEM images of gel dosimeters to accurately convert micro-scale structural features to absorbed doses. The proposed method may extend the feasibility of applying gel dosimeters in the fields of diagnostic radiology and radiation protection.

  18. Assessment and characterization of the total geometric uncertainty in Gamma Knife radiosurgery using polymer gels.

    Science.gov (United States)

    Moutsatsos, A; Karaiskos, P; Petrokokkinos, L; Sakelliou, L; Pantelis, E; Georgiou, E; Torrens, M; Seimenis, I

    2013-03-01

    This work proposes and implements an experimental methodology, based on polymer gels, for assessing the total geometric uncertainty and characterizing its contributors in Gamma Knife (GK) radiosurgery. A treatment plan consisting of 26, 4-mm GK single shot dose distributions, covering an extended region of the Leksell stereotactic space, was prepared and delivered to a polymer gel filled polymethyl methacrylate (PMMA) head phantom (16 cm diameter) used to accurately reproduce every link in the GK treatment chain. The center of each shot served as a "control point" in the assessment of the GK total geometric uncertainty, which depends on (a) the spatial dose delivery uncertainty of the PERFEXION GK unit used in this work, (b) the spatial distortions inherent in MR images commonly used for target delineation, and (c) the geometric uncertainty contributor associated with the image registration procedure performed by the Leksell GammaPlan (LGP) treatment planning system (TPS), in the case that registration is directly based on the apparent fiducial locations depicted in each MR image by the N-shaped rods on the Leksell localization box. The irradiated phantom was MR imaged at 1.5 T employing a T2-weighted pulse sequence. Four image series were acquired by alternating the frequency encoding axis and reversing the read gradient polarity, thus allowing the characterization of the MR-related spatial distortions. MR spatial distortions stemming from main field (B0) inhomogeneity as well as from susceptibility and chemical shift phenomena (also known as sequence dependent distortions) were found to be of the order of 0.5 mm, while those owing to gradient nonlinearities (also known as sequence independent distortions) were found to increase with distance from the MR scanner isocenter extending up to 0.47 mm at an Euclidean distance of 69.6 mm. Regarding the LGP image registration procedure, the corresponding average contribution to the total geometric uncertainty ranged from

  19. High-Performance and Stable Gel-State Dye-Sensitized Solar Cells Using Anodic TiO2 Nanotube Arrays and Polymer-Based Gel Electrolytes.

    Science.gov (United States)

    Seidalilir, Zahra; Malekfar, Rasoul; Wu, Hui-Ping; Shiu, Jia-Wei; Diau, Eric Wei-Guang

    2015-06-17

    Highly ordered and vertically oriented TiO2 nanotube (NT) arrays were synthesized with potentiostatic anodization of Ti foil and applied to fabricate gel-state dye-sensitized solar cells (DSSCs). The open structure of the TiO2 NT facilitates the infiltration of the gel-state electrolyte; their one-dimensional structural feature provides effective charge transport. TiO2 NTs of length L=15-35 μm were produced on anodization for periods of t=5-15 h at a constant voltage of 60 V, and sensitized with N719 for photovoltaic characterization. A commercially available copolymer, poly(methyl methacrylate-co-ethyl acrylate) (PMMA-EA), served as a gelling agent to prepare a polymer-gel electrolyte (PGE) for DSSC applications. The PGE as prepared exhibited a maximum conductivity of 4.58 mS cm(-1) with PMMA-EA (7 wt %). The phase transition temperature (Tp) of the PGE containing PMMA-EA at varied concentrations was determined on the basis of the viscosities measured at varied temperatures. Tp increased with increasing concentration of PMMA-EA. An NT-DSSC with L=30 μm assembled using a PGE containing PMMA-EA (7 wt %) exhibited an overall power conversion efficiency (PCE) of 6.9%, which is comparable with that of a corresponding liquid-type device, PCE=7.1%. Moreover, the gel-state NT-DSSC exhibited excellent thermal and light-soaking enduring stability: the best device retained ∼90% of its initial efficiency after 1000 h under 1 sun of illumination at 50 °C, whereas its liquid-state counterpart decayed appreciably after light soaking for 500 h.

  20. Evaluation of Dose Distribution Accuracy in HDR Brachytherapy of Esophagus Cancer Based on MRI Normoxic Polymer Gel Dosimetry

    Directory of Open Access Journals (Sweden)

    Mohammad Taghi Bahreyni Toossi

    2010-03-01

    Full Text Available Introduction: The purpose of this work was to study the ability of MRI normoxic polymer gel dosimetry for evaluating the dose distribution in HDR brachytherapy of esophagial cancer at Imam Reza brachytherapy center (Mashhad, Iran. Materials and Methods: Initially, 2liters of normoxic gel (MAGIC was fabricated and then poured into 12 calibration test tubes and placed in a perspex walled phantom. The gel phantom was irradiated with a brachytherapy remote-afterloader unit using a cobalt-60 brachytherapy source and the test tubes were irradiated with a range of known doses with a cobalt-60 teletherapy unit. Imaging was performed with a multi-spin-echo protocol and a T2 quantitative technique using a Siemens 1.5 T MRI machine. The MRI images were transferred to a computer and then image processing was performed in the MATLAB environment to extract R2 maps of the irradiated area. Results: In this study and at the reference point, the dose deviation between the gel dosimetry and the calculated data was 4.5%. The distance to agreement (DTA for dose profiles was 2.7 mm. Also, dose sensitivity of the MAGIC gel dosimeter was 0.693 S-1Gy-1 (R2 =0.9376. Conclusion: In this work, the data obtained from TPS calculations were found in very good agreement with the measured results provided by gel dosimetry. It was evaluated using a comparison of isodoses and dose at the reference point, and dose profile verification. It is also concluded that the gel dosimetry systems have proven to be a useful tool for dosimetry in clinical radiotherapy applications.

  1. Configurational Molecular Glue: One Optically Active Polymer Attracts Two Oppositely Configured Optically Active Polymers.

    Science.gov (United States)

    Tsuji, Hideto; Noda, Soma; Kimura, Takayuki; Sobue, Tadashi; Arakawa, Yuki

    2017-03-24

    D-configured poly(D-lactic acid) (D-PLA) and poly(D-2-hydroxy-3-methylbutanoic acid) (D-P2H3MB) crystallized separately into their homo-crystallites when crystallized by precipitation or solvent evaporation, whereas incorporation of L-configured poly(L-2-hydroxybutanoic acid) (L-P2HB) in D-configured D-PLA and D-P2H3MB induced co-crystallization or ternary stereocomplex formation between D-configured D-PLA and D-P2H3MB and L-configured L-P2HB. However, incorporation of D-configured poly(D-2-hydroxybutanoic acid) (D-P2HB) in D-configured D-PLA and D-P2H3MB did not cause co-crystallization between D-configured D-PLA and D-P2H3MB and D-configured D-P2HB but separate crystallization of each polymer occurred. These findings strongly suggest that an optically active polymer (L-configured or D-configured polymer) like unsubstituted or substituted optically active poly(lactic acid)s can act as "a configurational or helical molecular glue" for two oppositely configured optically active polymers (two D-configured polymers or two L-configured polymers) to allow their co-crystallization. The increased degree of freedom in polymer combination is expected to assist to pave the way for designing polymeric composites having a wide variety of physical properties, biodegradation rate and behavior in the case of biodegradable polymers.

  2. Auto-Origami and Soft Programmable Transformers: Simulation Studies of Liquid Crystal Elastomers and Swelling Polymer Gels

    Science.gov (United States)

    Konya, Andrew; Santangelo, Christian; Selinger, Robin

    2014-03-01

    When the underlying microstructure of an actuatable material varies in space, simple sheets can transform into complex shapes. Using nonlinear finite element elastodynamic simulations, we explore the design space of two such materials: liquid crystal elastomers and swelling polymer gels. Liquid crystal elastomers (LCE) undergo shape transformations induced by stimuli such as heating/cooling or illumination; complex deformations may be programmed by ``blueprinting'' a non-uniform director field in the sample when the polymer is cross-linked. Similarly, swellable gels can undergo shape change when they are swollen anisotropically as programmed by recently developed halftone gel lithography techniques. For each of these materials we design and test programmable motifs which give rise to complex deformation trajectories including folded structures, soft swimmers, apertures that open and close, bas relief patterns, and other shape transformations inspired by art and nature. In order to accommodate the large computational needs required to model these materials, our 3-d nonlinear finite element elastodynamics simulation algorithm is implemented in CUDA, running on a single GPU-enabled workstation.

  3. A colourimetric method for the determination of the degree of chemical cross-linking in aspartic acid-based polymer gels

    Directory of Open Access Journals (Sweden)

    B. Gyarmati

    2015-02-01

    Full Text Available A 2,4,6-trinitrobenzenesulphonic acid (TNBS-based assay is developed to determine the degree of chemical cross-linking in aspartic acid-based polymer gels. The conventional colourimetric method for the quantitative determination of amine groups is difficult to use in polymer networks; thus, an improved method is developed to analyse polymer gels swollen in dimethyl sulfoxide (DMSO. Reaction products of the derivatizing reaction are examined by NMR. The chemical stability of the reagent is increased in DMSO, and the method shows satisfactory linearity and accuracy. The degree of chemical cross-linking in the investigated gels is close to its theoretical maximum, but the conversion of the pendant amine groups to cross-linking points is strongly dependent on the feed composition of the gels.

  4. The effect of multifunctional polymer-based gels on wound healing in full thickness bacteria-contaminated mouse skin wound models.

    Science.gov (United States)

    Yates, Cecelia C; Whaley, Diana; Babu, Ranjith; Zhang, Jianying; Krishna, Priya; Beckman, Eric; Pasculle, A William; Wells, Alan

    2007-09-01

    We determined whether a two-part space-conforming polyethylene glycol/dopa polymer-based gel promoted healing of contaminated wounds in mice. This silver-catalysed gel was previously developed to be broadly microbiocidal in vitro while being biocompatible with human wound cell functioning. Full-thickness wounds were created on the backs of mice. The wounds were inoculated with 10(4) CFU of each of four common skin wound contaminants, Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumanii and Clostridium perfringens. The wounds were then treated with our multifunctional polymer-based gel, the commercially available NewSkin product, or left to heal untreated. The untreated wounds were overtly infected, and presented detectable bacterial loads over the entire 21-day healing period, while the gel and NewSkin groups presented significantly smaller rises in bacterial levels and were cleared of detectable colonies by the third week, with the gel group clearing the bacteria earlier. While all three groups healed their wounds, the polymer-based gel-treated group demonstrated significantly earlier re-epithelialization and dermal maturation (Phealing wound. These preclinical studies show that the anti-microbial polymer gel not only supports but also accelerates healing of bacterially contaminated wounds.

  5. High-performance gel electrolytes with tetra-armed polymer network for Li ion batteries

    Science.gov (United States)

    Hazama, Taisuke; Fujii, Kenta; Sakai, Takamasa; Aoki, Masahiro; Mimura, Hideyuki; Eguchi, Hisao; Todorov, Yanko; Yoshimoto, Nobuko; Morita, Masayuki

    2015-07-01

    An organo gel with only 6 wt % tetra-armed poly(ethylene glycol), TetraPEG, was prepared and applied as a novel gel electrolyte for Li ion batteries (LIBs). The TetraPEG gel electrolyte containing 1.0 M LiPF6 in binary or ternary mixtures, i.e., EC + DEC and EC + DEC + TFEP (EC: ethylene carbonate, DEC: diethyl carbonate and TFEP: tris(2,2,2-trifluoroethyl)phosphate showed high ionic conductivity required for the use in LIB systems. The TetraPEG gel based on ternary EC + DEC + TFEP system acts as a nonflammable gel electrolyte at the TFEP content higher than 20 vol%. In cyclic voltammetry and charge/discharge cycling tests, the TetraPEG gel electrolytes showed good reversibility for a graphite negative electrode.

  6. Simultaneous immunoblotting analysis with activity gel electrophoresis and 2-D gel electrophoresis.

    Science.gov (United States)

    Lee, Der-Yen; Chang, Geen-Dong

    2015-01-01

    Diffusion blotting method can couple immunoblotting analysis with another biochemical technique in a single polyacrylamide gel, however, with lower transfer efficiency as compared to the conventional electroblotting method. Thus, with diffusion blotting, protein blots can be obtained from an SDS polyacrylamide gel for zymography assay, from a native polyacrylamide gel for electrophoretic mobility shift assay (EMSA) or from a 2-D polyacrylamide gel for large-scale screening and identification of a protein marker. Thereafter, a particular signal in zymography, electrophoretic mobility shift assay, and 2-dimensional gel can be confirmed or identified by simultaneous immunoblotting analysis with a corresponding antiserum. These advantages make diffusion blotting desirable when partial loss of transfer efficiency can be tolerated or be compensated by a more sensitive immunodetection reaction using enhanced chemiluminescence detection.

  7. Electrical and electrochemical studies of poly(vinylidene fluoride)-clay nanocomposite gel polymer electrolytes for Li-ion batteries

    Science.gov (United States)

    Deka, M.; Kumar, A.

    A study is conducted on the electrical and electrochemical properties of nanocomposite polymer electrolytes based on intercalation of poly(vinylidene fluoride) (PVdF) polymer into the galleries of organically modified montmorillonite (MMT) clay. A solution intercalation technique is employed for nanocomposite formation with varying clay loading from 0 to 4 wt.%. X-ray diffraction results show the β phase formation of PVdF on intercalation. Transmission electron microscopy reveals the formation of partially exfoliated nanocomposites. The nanocomposites are soaked with 1 M LiClO 4 in a 1:1 (v/v) solution of propylene carbonate (PC) and diethyl carbonate (DEC) to obtain the required gel electrolytes. The structural conformation of the nanocomposite electrolytes is examined by Fourier transform infrared spectroscopy analysis. Examination with a.c. impedance spectroscopy reveals that the ionic conductivity of the nanocomposite gel polymer electrolytes increases with increase in clay loading and attains a maximum value of 2.3 × 10 -3 S cm -1 for a 4 wt.% clay loading at room temperature. The same composition exhibits enhancement in the electrochemical and interfacial properties as compared with that of a clay-free electrolyte system.

  8. A Review on Polymers Used In In-Situ Gel Drug Delivery Systems

    OpenAIRE

    Shaikh RG; Shah SV; Patel KN; Patel BA; Patel PA

    2012-01-01

    In situ gel drug delivery systems are used in sol form before administration in the body, but onceadministered, undergo gelation in situ, to form a gel. The formation of gel depends on factors liketemperature modulation, pH change, presence of ions and ultraviolet irradiation, electrical sensitivity,enzyme sensitive from which drug get released in a sustained and controlled manner. Typically, aqueoussolutions of hydrogels used in biomedical applications are liquid at ambient temperature and g...

  9. Preparation of organic/inorganic composite membranes using two types of polymer matrix via a sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Park, Seung-Hee [School of Chemical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea); Polymer Electrolyte Fuel Cell Research Center, Hydrogen and Fuel Cell Department, Korea Institute of Energy Research (KIER), 71-2 Jang-dong, Yuseong-gu, Daejeon 305-343 (Korea); Park, Jin-Soo; Yim, Sung-Dae; Park, Seok-Hee; Kim, Chang-Soo [Polymer Electrolyte Fuel Cell Research Center, Hydrogen and Fuel Cell Department, Korea Institute of Energy Research (KIER), 71-2 Jang-dong, Yuseong-gu, Daejeon 305-343 (Korea); Lee, Young-Moo [School of Chemical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea)

    2008-07-01

    Organic/inorganic composite membranes were prepared using two different polymers. BPO{sub 4} particles were introduced into polymers via an in situ sol-gel process. Pre-/post-sulfonated polymers were used to prepare composite membranes as matrix. Pre-sulfonated poly(aryl ether ketone) (SPAEK-6F) copolymer was synthesized via nucleophilic aromatic substitution. Degree of sulfonation was adjusted by the percentage of sulfonated monomer. Post-sulfonated poly(ether ether ketone) (SPEEK) was prepared using concentrated sulfuric acid as sulfonation agent. The membranes were characterized in terms of the ion-exchange capacity (IEC), proton conductivity, water uptake, AFM, SEM and their thermal properties. The SPAEK-6F plain membranes showed higher proton conductivity than that of the SPEEK plain membranes at similar water uptake or IEC due to their structural difference. SEM images of the composite membranes showed that the BPO{sub 4} particles were homogenously dispersed in the polymer matrices and BPO{sub 4} particle size was greatly influenced by polymer matrix. The SPAEK-6F/BPO{sub 4} composite membranes had much smaller BPO{sub 4} particle size than the SPEEK/BPO{sub 4} composite membranes due to well dispersion of BPO{sub 4} sol-like particulates in SPAEK-6F polymer solutions forming more hydrophobic/hydrophilic nanophase than SPEEK polymer solutions. The latter containing a few micrometer-scale BPO{sub 4} particles showed higher proton conductivity than the former containing hundreds nanometer-scale BPO{sub 4} particles at similar water uptake due to the increase in freezable water and effect of particle size. (author)

  10. Preparation of organic/inorganic composite membranes using two types of polymer matrix via a sol-gel process

    Science.gov (United States)

    Park, Seung-Hee; Park, Jin-Soo; Yim, Sung-Dae; Park, Seok-Hee; Lee, Young-Moo; Kim, Chang-Soo

    Organic/inorganic composite membranes were prepared using two different polymers. BPO 4 particles were introduced into polymers via an in situ sol-gel process. Pre-/post-sulfonated polymers were used to prepare composite membranes as matrix. Pre-sulfonated poly(aryl ether ketone) (SPAEK-6F) copolymer was synthesized via nucleophilic aromatic substitution. Degree of sulfonation was adjusted by the percentage of sulfonated monomer. Post-sulfonated poly(ether ether ketone) (SPEEK) was prepared using concentrated sulfuric acid as sulfonation agent. The membranes were characterized in terms of the ion-exchange capacity (IEC), proton conductivity, water uptake, AFM, SEM and their thermal properties. The SPAEK-6F plain membranes showed higher proton conductivity than that of the SPEEK plain membranes at similar water uptake or IEC due to their structural difference. SEM images of the composite membranes showed that the BPO 4 particles were homogenously dispersed in the polymer matrices and BPO 4 particle size was greatly influenced by polymer matrix. The SPAEK-6F/BPO 4 composite membranes had much smaller BPO 4 particle size than the SPEEK/BPO 4 composite membranes due to well dispersion of BPO 4 sol-like particulates in SPAEK-6F polymer solutions forming more hydrophobic/hydrophilic nanophase than SPEEK polymer solutions. The latter containing a few micrometer-scale BPO 4 particles showed higher proton conductivity than the former containing hundreds nanometer-scale BPO 4 particles at similar water uptake due to the increase in freezable water and effect of particle size.

  11. Role of precursors and coating polymers in sol-gel chemistry toward enhanced selectivity and efficiency in solid phase microextraction.

    Science.gov (United States)

    Bagheri, Habib; Piri-Moghadam, Hamed; Ahdi, Tayebeh

    2012-09-12

    To evaluate the selectivity and efficiency of solid phase microextraction (SPME) fiber coatings, synthesized by sol-gel technology, roles of precursors and coating polymers were extensively investigated. An on-line combination of capillary microextraction (CME) technique and high performance liquid chromatography (HPLC) was set up to perform the investigation. Ten different fiber coatings were synthesized in which five of them contained only the precursor and the rests were prepared using both the precursor and coating polymer. All the coatings were chemically bonded to the inner surface of copper tubes, intended to be used as the CME device and already functionalized by self-assembly monolayers of 3-(mercaptopropyl)trimethoxysilane (3MPTMOS). The selected precursors included tetramethoxysilane (TMOS), 3-(trimethoxysilyl)propylmethacrylate (TMSPMA), 3-(triethoxysilyl)-propylamine (TMSPA), 3MPTMOS, [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane (EPPTMOS) while poly(ethyleneglycol) (PEG) was chosen as the coating polymer. The effects of different precursors on the extraction efficiency and selectivity, was studied by selecting a list of compounds ranging from non-polar to polar ones, i.e. polycyclic aromatic hydrocarbon, herbicides, estrogens and triazines. The results from CME-HPLC analysis revealed that there is no significant difference between precursors, except TMOS, in which has the lowest extraction efficiency. Most of the selected precursors have rather similar interactions toward the selected analytes which include Van der Walls, dipole-dipole and hydrogen bond while TMOS has only dipole-dipole interaction and therefore the least efficiency. TMOS is silica but the other sorbents are organically modified silica (ORMOSIL). Our investigation revealed that it is rather impossible to prepare a selective coating using conventional sol-gel methodologies. The comparison study performed among the fiber coatings contained only a precursor and those synthesized by a

  12. Evaluation of MRI-based Polymer Gel Dosimetry for Measurement of CT Dose Index (CTDI on 64 slices CT Scanners

    Directory of Open Access Journals (Sweden)

    Leaila Karimi-Afshar

    2009-06-01

    Full Text Available Introduction: Computed tomography (CT has numerous applications in clinical procedures but its main problem is its high radiation dose to the patients compared to other imaging modalities using x-ray. CT delivers approximately high doses to the nearby tissues due to the scattering effect, fan beam (beam divergence and limited collimator efficiency. The radiation dose from multi-slice scanners is greater than the single-slice scanners and since multi-slice scanners increasingly employ a wide beam, 100 mm ion chambers currently used in measuring the CTDI100, are not capable of accurately measuring the total dose profile of the slice width. Therefore, the CT dose is underestimated by using them. The purpose of this study is to measure the Computed Tomography Dose Index (CTDI of a GE multi-slice CT scanner (64-slice using polymer gel dosimetry based on MRI imaging (MRPD. CTDI is the sum of point doses along the central axis and estimates the average patient dose during CT scanning. Materials and Methods: For measuring CTDI, after designing and fabricating the phantom and preparing the MAGIC gel, MRI imaging using a 1.5 T Siemens MRI scanner was performed with the imaging parameters of ST = 2 mm, NEX = 1, TE = 20-640 ms and TR = 2000 ms. CTDI was measured with a 100 mm ion chamber (CTDI100 and also the MAGIC gel with MRPD method for 10 mm and 40 mm CT scan nominal widths. Results: Following the measurement of the CTDI100 for 10 mm and 40 mm nominal slice widths of the multi-slice scanner using both ion chamber and MAGIC gel, the results showed that the ion chamber underestimates CTDI100 by 28.71% and 14.03% compared to gel for 10 mm and 40 mm respectively. Discussion and Conclusion: It was concluded from this study that gel dosimeters have the capability to measure CTDI in wide beams of multi-slice CT scanners whereas 100 mm standard ion chamber due to its limited length is not reliable even for a 10 mm beam width. In addition, due to the 3

  13. Three Gel States of Colloidal Composites Consisting of Polymer-Brush-Afforded Silica Particles and a Nematic Liquid Crystal with Distinct Viscoelastic and Optical Properties.

    Science.gov (United States)

    Kawata, Yuki; Yamamoto, Takahiro; Kihara, Hideyuki; Yamamura, Yasuhisa; Saito, Kazuya; Ohno, Kohji

    2016-11-02

    Colloidal composites consisting of polymer-brush-afforded silica particles (P-SiPs) and a nematic liquid crystal (LC) exhibited three gel states with distinct viscoelastic and/or optical properties depending on temperature: (1) opaque hard gel, (2) translucent hard gel, and (3) translucent soft gel. We demonstrated that the transitions of the optical property and the hardness of the gels were due to the phase transition of the LC matrix and the glass transition of the grafted polymers of P-SiPs, respectively. We then revealed that the gelation (the formation of the translucent soft gel) was caused by the phase separation of P-SiPs and LC matrix in an isotropic phase based on spinodal decomposition. In addition, the particle concentration and molecular weight of the grafted polymer of P-SiPs were observed to significantly affect the elastic moduli and thermal stability of the composite gels. By the addition of an azobenzene derivative into an LC matrix, we achieved photochemical switching of the transparency of the composites based on the photoinduced phase transition of LCs, while keeping self-supporting ability of the composite gel.

  14. Technical Note: Preliminary investigations into the use of a functionalised polymer to reduce diffusion in Fricke gel dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Smith, S. T., E-mail: s164.smith@qut.edu.au; Masters, K.-S.; Hosokawa, K.; Blinco, J. P.; Trapp, J. V. [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane 4000 (Australia); Crowe, S. B. [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane 4000, Australia and Cancer Care Services, Royal Brisbane and Women’s Hospital, Brisbane 4006 (Australia); Kairn, T. [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane 4000, Australia and Genesis Cancer Care Queensland, Brisbane 4066 (Australia)

    2015-12-15

    Purpose: A modification of the existing PVA-FX hydrogel has been made to investigate the use of a functionalised polymer in a Fricke gel dosimetry system to decrease Fe{sup 3+} diffusion. Methods: The chelating agent, xylenol orange, was chemically bonded to the gelling agent, polyvinyl alcohol (PVA) to create xylenol orange functionalised PVA (XO-PVA). A gel was created from the XO-PVA (20% w/v) with ferrous sulfate (0.4 mM) and sulfuric acid (50 mM). Results: This resulted in an optical density dose sensitivity of 0.014 Gy{sup −1}, an auto-oxidation rate of 0.0005 h{sup −1}, and a diffusion rate of 0.129 mm{sup 2} h{sup −1}; an 8% reduction compared to the original PVA-FX gel, which in practical terms adds approximately 1 h to the time span between irradiation and accurate read-out. Conclusions: Because this initial method of chemically bonding xylenol orange to polyvinyl alcohol has inherently low conversion, the improvement on existing gel systems is minimal when compared to the drawbacks. More efficient methods of functionalising polyvinyl alcohol with xylenol orange must be developed for this system to gain clinical relevance.

  15. Polymer Basics: Classroom Activities Manipulating Paper Clips to Introduce the Structures and Properties of Polymers

    Science.gov (United States)

    Umar, Yunusa

    2014-01-01

    A simple and effective hands-on classroom activity designed to illustrate basic polymer concepts is presented. In this activity, students build primary structures of homopolymers and different arrangements of monomers in copolymer using paper clips as monomers. The activity supports formation of a basic understanding of polymer structures,…

  16. Polymer Basics: Classroom Activities Manipulating Paper Clips to Introduce the Structures and Properties of Polymers

    Science.gov (United States)

    Umar, Yunusa

    2014-01-01

    A simple and effective hands-on classroom activity designed to illustrate basic polymer concepts is presented. In this activity, students build primary structures of homopolymers and different arrangements of monomers in copolymer using paper clips as monomers. The activity supports formation of a basic understanding of polymer structures,…

  17. Does nitrogen gas bubbled through a low density polymer gel dosimeter solution affect the polymerization process?

    Directory of Open Access Journals (Sweden)

    Daryoush Shahbazi-Gahrouei

    2015-01-01

    Conclusion: It appeared that reactions between gelatin-free radicals and monomers, due to an increase in the gel temperature during rotation in the household mixer, led to a higher R 2 -background response. In the second type of gel, it seemed that the collapse of the nitrogen bubbles was the main factor that affected the R 2 -responses.

  18. Artificial Neural Network and Response Surface Methodology Modeling in Ionic Conductivity Predictions of Phthaloylchitosan-Based Gel Polymer Electrolyte

    Directory of Open Access Journals (Sweden)

    Ahmad Danial Azzahari

    2016-01-01

    Full Text Available A gel polymer electrolyte system based on phthaloylchitosan was prepared. The effects of process variables, such as lithium iodide, caesium iodide, and 1-butyl-3-methylimidazolium iodide were investigated using a distance-based ternary mixture experimental design. A comparative approach was made between response surface methodology (RSM and artificial neural network (ANN to predict the ionic conductivity. The predictive capabilities of the two methodologies were compared in terms of coefficient of determination R2 based on the validation data set. It was shown that the developed ANN model had better predictive outcome as compared to the RSM model.

  19. Quasi-solid-state nanocrystalline TiO2 solar cells using gel network polymer electrolytes based on polysiloxanes

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A quasi-solid-state dye-sensitized nanocrystalline porous TiO2 film solar cell was fabricated using a novel gel network polymer electrolyte based on polysiloxanes with both polyethylene oxide internal plasticized side chains and quaternary ammonium groups. The cell exhibited better photoelectrical conversion performance under 60 mW/cm2 irradiation. The short photocurrent (Isc) of 5.0 mA/cm2 and open voltage (Voc) of 0.68 V were achieved, and the energy conversion efficiency (η) and fill factor (ff) were 3.4% and 0.60, respectively.

  20. Preliminary study of MAGAT polymer gel dosimetry for boron-neutron capture therapy

    Science.gov (United States)

    Hayashi, Shin-ichiro; Sakurai, Yoshinori; Uchida, Ryohei; Suzuki, Minoru; Usui, Shuji; Tominaga, Takahiro

    2015-01-01

    MAGAT gel dosimeter with boron is irradiated in Heavy Water Neutron Irradiation Facility (HWNIF) of Kyoto University Research Reactor (KUR). The cylindrical gel phantoms are exposed to neutron beams of three different energy spectra (thermal neutron rich, epithermal and fast neutron rich and the mixed modes) in air. Preliminary results corresponding to depth-dose responses are obtained as the transverse relaxation rate (R2=1/T2) from magnetic resonance imaging data. As the results MAGAT gel dosimeter has the higher sensitivity on thermal neutron than on epi-thermal and fast neutron, and the gel with boron showed an enhancement and a change in the depth-R2 response explicitly. From these results, it is suggested that MAGAT gel dosimeter can be an effective tool in BNCT dosimetry.

  1. A composite membrane based on a biocompatible cellulose as a host of gel polymer electrolyte for lithium ion batteries

    Science.gov (United States)

    Xiao, S. Y.; Yang, Y. Q.; Li, M. X.; Wang, F. X.; Chang, Z.; Wu, Y. P.; Liu, X.

    2014-12-01

    A composite polymer membrane is prepared by coating poly(vinylidene fluoride) (PVDF) on the surface of a membrane based on methyl cellulose (MC) which is environmentally friendly and cheap. Its characteristics are investigated by scanning electron microscopy, FT-IR, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The outer PVDF layers are porous which results in high electrolyte uptake and the lithium ion transference number is much larger than that of the pure MC. Moreover, the cell based on Li//LiFePO4 delivers high discharge capacity and good rate behavior in the range of 4.2-2.5 V when the composite membrane is used as the separator and the host of a gel polymer electrolyte, lithium as the counter and reference electrode, and LiFePO4 as cathode. The obtained results suggest that this unique composite membrane shows great attraction in the lithium ion batteries with high safety and low cost.

  2. Colloidal interactions of inorganic nanoparticles grafted with zwitterionic polymer brushes and gels by surface-mediated seeded polymerization.

    Science.gov (United States)

    An, Soyoun; Choi, Sang Koo; Cho, Jang Woo; Kim, Hyun Tae; Kim, Jin Woong

    2014-08-01

    A robust and straightforward approach is introduced to synthesize inorganic nanoparticles chemically grafted with a zwitterionic poly(2-methacryroyloxyethylphosphorylcholine) (PMPC) thin layers. The synthesis method is based on the surface-mediated seeded polymerization. In order to observe how the polymer chain architectures affect colloidal interactions, the zinc oxide nanoparticles are grafted with linear brushes and with a thin hydrogel layer, respectively. The thickness of PMPC shell layers spans a few nanometers. The studies on suspension rheology for the nanoparticles show that the nanoparticles with PMPC brushes show the stronger repulsive force than those with the PMPC gel shell due to the entropic stabilization. When the shear force is applied to the Pickering emulsion produced by assembly of the nanoparticles, it is noticeable that the presence of PMPC brushes on the particles rather enhances the drop-to-drop attraction, which presumably stems from the entanglement of polymer chains between the contacted interfacial planes of the emulsion droplets during shearing.

  3. Emulsification-Induced Homohelicity in Racemic Helical Polymer for Preparing Optically Active Helical Polymer Nanoparticles.

    Science.gov (United States)

    Zhao, Biao; Deng, Jinrui; Deng, Jianping

    2016-04-01

    Optically active nano- and microparticles have constituted a significant category of advanced functional materials. However, constructing optically active particles derived from synthetic helical polymers still remains as a big challenge. In the present study, it is attempted to induce a racemic helical polymer (containing right- and left-handed helices in equal amount) to prefer one predominant helicity in aqueous media by using emulsifier in the presence of chiral additive (emulsification process). Excitingly, the emulsification process promotes the racemic helical polymer to unify the helicity and directly provides optically active nanoparticles constructed by chirally helical polymer. A possible mechanism is proposed to explain the emulsification-induced homohelicity effect. The present study establishes a novel strategy for preparing chirally helical polymer-derived optically active nanoparticles based on racemic helical polymers.

  4. Adsorption characteristics, recognition properties, and preliminary application of nordihydroguaiaretic acid molecularly imprinted polymers prepared by sol-gel surface imprinting technology

    Science.gov (United States)

    Liao, Sen; Zhang, Wen; Long, Wei; Hou, Dan; Yang, Xuechun; Tan, Ni

    2016-02-01

    In this paper, a new core-shell composite of nordihydroguaiaretic acid (NDGA) molecularly imprinted polymers layer-coated silica gel (MIP@SiO2) was prepared through sol-gel technique and applied as a material for extraction of NDGA from Ephedra. It was synthesized using NDGA as the template molecule, γ-aminopropyltriethoxysilane (APTS) and methyltriethoxysilane (MTEOS) as the functional monomers, tetraethyl orthosilicate (TEOS) as the cross-linker and ethanol as the porogenic solvent in the surface of silica. The non-imprinted polymers layer-coated silica gel (NIP@SiO2) were prepared with the same procedure, but with the absence of template molecule. In addition, the optimum adsorption affinity occurred when the molar ratio of NDGA:APTS:MTEOS:TEOS was 1:6:2:80. The prepared MIP@SiO2 and NIP@SiO2 were analyzed by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Fourier transform-infrared spectroscopy (FT-IR). Their affinity properties to NDGA were evaluated through dynamic adsorption, static adsorption, and selective recognition experiments, and the results showed the saturated adsorption capacity of MIP@SiO2 could reach to 5.90 mg g-1, which was two times more than that of NIP@SiO2. High performance liquid chromatography (HPLC) was used to evaluate the extraction of NDGA from the medicinal plant ephedra by the above prepared materials, and the results indicated that the MIP@SiO2 had potential application in separation of the natural active component NDGA from medicinal plants.

  5. A novel gel based on an ionic complex from a dendronized polymer and ciprofloxacin: Evaluation of its use for controlled topical drug release.

    Science.gov (United States)

    García, Mónica C; Cuggino, Julio C; Rosset, Clarisa I; Páez, Paulina L; Strumia, Miriam C; Manzo, Ruben H; Alovero, Fabiana L; Alvarez Igarzabal, Cecilia I; Jimenez-Kairuz, Alvaro F

    2016-12-01

    The development and characterization of a novel, gel-type material based on a dendronized polymer (DP) loaded with ciprofloxacin (CIP), and the evaluation of its possible use for controlled drug release, are presented in this work. DP showed biocompatible and non-toxic behaviors in cultured cells, both of which are considered optimal properties for the design of a final material for biomedical applications. These results were encouraging for the use of the polymer loaded with CIP (as a drug model), under gel form, in the development of a new controlled-release system to be evaluated for topical administration. First, DP-CIP ionic complexes were obtained by an acid-base reaction using the high density of carboxylic acid groups of the DP and the amine groups of the CIP. The complexes obtained in the solid state were broadly characterized using FTIR spectroscopy, XRP diffraction, DSC-TG analysis and optical microscopy techniques. Gels based on the DP-CIP complexes were easily prepared and presented excellent mechanical behaviors. In addition, optimal properties for application on mucosal membranes and skin were achieved due to their high biocompatibility and acute skin non-irritation. Slow and sustained release of CIP toward simulated physiological fluids was observed in the assays (in vitro), attributed to ion exchange phenomenon and to the drug reservoir effect. An in vitro bacterial growth inhibition assay showed significant CIP activity, corresponding to 38 and 58% of that exhibited by a CIP hydrochloride solution at similar CIP concentrations, against Staphylococcus aureus and Pseudomonas aeruginosa, respectively. However, CIP delivery was appropriate, both in terms of magnitude and velocity to allow for a bactericidal effect. In conclusion, the final product showed promising behavior, which could be exploited for the treatment of topical and mucosal opportunistic infections in human or veterinary applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Pharmacodynamic activity of Dapivirine and Maraviroc single entity and combination topical gels for HIV-1 prevention

    Science.gov (United States)

    Dezzutti, Charlene S.; Yandura, Sarah; Wang, Lin; Moncla, Bernard; Teeple, Elizabeth A.; Devlin, Brid; Nuttall, Jeremy; Brown, Elizabeth R.; Rohan, Lisa C.

    2015-01-01

    Purpose Dapivirine (DPV), a non-nucleoside reverse transcriptase inhibitor, and maraviroc (MVC), a CCR5 antagonist, were formulated into aqueous gels designed to prevent mucosal HIV transmission. Methods 0.05% DPV, 0.1% MVC, 0.05% DPV/0.1% MVC and placebo gels were evaluated for pH, viscosity, osmolality, and in vitro release. In vitro assays and mucosal tissues were used to evaluate anti-HIV activity. Viability (Lactobacilli only) and epithelial integrity in cell lines and mucosal tissues defined safety. Results The gels were acidic and viscous. DPV gel had an osmolality of 893 mOsm/kg while the other gels had an osmolality of <100 mOsm/kg. MVC release was similar from the single and combination gels (~5 μg/cm2/min1/2), while DPV release was 10-fold less from the single as compared to the combination gel (0.4331 μg/cm2/min1/2). Titrations of the gels showed 10-fold more drug was needed to protect ectocervical than colonic tissue. The combination gel showed ~10- and 100-fold improved activity as compared to DPV and MVC gel, respectively. All gels were safe. Conclusions The DPV/MVC gel showed a benefit blocking HIV infection of mucosal tissue compared to the single entity gels. Combination products with drugs affecting unique steps in the viral replication cycle would be advantageous for HIV prevention. PMID:26078001

  7. Bioorganically doped sol-gel materials containing amyloglucosidase activity

    Directory of Open Access Journals (Sweden)

    Vlad-Oros Beatrice

    2006-01-01

    Full Text Available Amyloglucosidase (AMG from Aspergillus niger was encapsulated in various matrices derived from tetraethoxysilane, methyltriethoxysilane, phenyltriethoxysilane and vinyltriacetoxysilane by different methods of immobilization. The immobilized enzyme was prepared by entrapment in two steps, in one-step and entrapment/deposition, respectively. The activities of the immobilized AMG were assayed and compared with that of the native enzyme. The effects of the organosilaneprecursors and their molar ratios, the immobilization method, the inorganic support (white ceramic, red ceramic, purolite, alumina, TiO2, celite, zeolite and enzyme loading upon the immobilized enzyme activity were tested. The efficiency of the sol-gel biocomposites can be improved through combination of the fundamental immobilization techniques and selection of the precursors.

  8. Organic-inorganic Polymer Nano-hybrids Based on Sol-gel Reaction

    Institute of Scientific and Technical Information of China (English)

    Yoshiki; Chujo

    2007-01-01

    1 Results Nano-ordered composite materials consisting of organic polymers and inorganic materials have been attracting attention for the purpose of the creation of high-performance or high-functional polymeric materials. Especially,the word of "polymer hybrid" claims the blends of organic and inorganic components at nano-level dispersion. By using this idea,an enhancement of mechanical strength of organic polymers with silica particles is possible.High transparency of this material is another important ...

  9. Synergetic effect of green tea on polymer gel dosimeter and determination of optimal wavelength to choose light source for optical computed tomography

    Directory of Open Access Journals (Sweden)

    Sathiya Raj

    2016-03-01

    Full Text Available Purpose: The ultimate aim of this study is to observe the effect of Green tea as a co-antioxidant in PAGAT gel dosimeter and evaluate the appropriate light source for scanning the PAGAT and NIPAM polymer gel.Methods: Both PAGAT (Poly Acrylamide Gelatin Tetrakis hydroxyl phosphonium chloride and NIPAM (N-Isopropyl acrylamide gel were prepared in normoxic condition. The green tea extract (GTE was prepared and tested only on PAGAT. Co-60 teletherapy machine has been used for irradiation purpose, and the gel samples were scanned using UV-Visible spectrophotometer. Water equivalency of the gel has been tested in terms of their electron density, effective atomic number and Ratio of oxygen and hydrogen (O/H. We have used NIST XCOM database to test the water equivalency.Results: In this study we found that the GTE added to the gel do not respond to the given doses. By adding sugar we can enhance the sensitivity of the gel. Further investigations are required to use Green tea as a co antioxidant concentration of THPC (Tetrakis hydroxymethyl phosphonium chloride. The optimal wavelength with different region for scanning the PAGAT is 450 to 480 nm (Blue region, for NIPAM it is 540 nm and 570 nm (Green and yellow region. The PAGAT and NIPAM showed better sensitivity at 510 nm. Both gels have their effective atomic number closer to water (NIPAM-7.2, PAGAT-7.379.Conclusion: As per our results, we concluded that GTE alone is not an effective co-antioxidant for polymer gels. When the GTE is combined with sugar and THPC, it protects the gel from pre-polymerization. This study strongly suggests that the blue light is an optimal source for scanning the PAGAT and green to yellow light for NIPAM gel. Though both gels were considered as water equivalent, the PAGAT is equivalent to water and the temporal stability of this gel is higher than NIPAM.

  10. The influence of polymer content on early gel-layer formation in HPMC matrices: The use of CLSM visualisation to identify the percolation threshold.

    Science.gov (United States)

    Mason, Laura Michelle; Campiñez, María Dolores; Pygall, Samuel R; Burley, Jonathan C; Gupta, Pranav; Storey, David E; Caraballo, Isidoro; Melia, Colin D

    2015-08-01

    Percolation theory has been used for several years in the design of HPMC hydrophilic matrices. This theory predicts that a minimum threshold content of polymer is required to provide extended release of drug, and that matrices with a lower polymer content will exhibit more rapid drug release as a result of percolation pathways facilitating the faster penetration of the aqueous medium. At present, percolation thresholds in HPMC matrices have been estimated solely through the mathematical modelling of dissolution data. This paper examines whether they can be also identified in a novel way: through the use of confocal laser scanning fluorescence microscopy (CLSM) to observe the morphology of the emerging gel layer during the initial period of polymer hydration and early gel formation at the matrix surface. In this study, matrices have been prepared with a polymer content of 5-30% w/w HPMC 2208 (Methocel K4M), with a mix of other excipients (a soluble drug (caffeine), lactose, microcrystalline cellulose and magnesium stearate) to provide a typical industrially realistic formulation. Dissolution studies, undertaken in water using USP apparatus 2 (paddle) at 50rpm, provided data for the calculation of the percolation threshold through relating dissolution kinetic parameters to the excipient volumetric fraction of the dry matrix. The HPMC percolation threshold estimated this way was found to be 12.8% v/v, which was equivalent to a matrix polymer content of 11.5% w/w. The pattern of polymer hydration and gel layer growth during early gel layer formation was examined by confocal laser scanning fluorescence microscopy (CLSM). Clear differences in gel layer formation were observed. At polymer contents above the estimated threshold a continuous gel layer was formed within 15min, whereas matrices with polymer contents below the threshold were characterised by irregular gel layer formation with little evidence of HPMC particle coalescence. According to percolation theory, this

  11. Development of dye-sensitized solar cells composed of liquid crystal embedded, electrospun poly(vinylidene fluoride-co-hexafluoropropylene) nanofibers as polymer gel electrolytes.

    Science.gov (United States)

    Ahn, Sung Kwang; Ban, Taewon; Sakthivel, P; Lee, Jae Wook; Gal, Yeong-Soon; Lee, Jin-Kook; Kim, Mi-Ra; Jin, Sung-Ho

    2012-04-01

    In order to overcome the problems associated with the use of liquid electrolytes in dye-sensitized solar cells (DSSCs), a new system composed of liquid crystal embedded, polymer electrolytes has been developed. For this purpose, three types of DSSCs have been fabricated. The cells contain electrospun poly(vinylidene fluoride-co-hexafluoropropylene) (e-PVdF-co-HFP) polymer gel electrolyte, with and without doping with the liquid crystal E7 and with a liquid electrolyte. The morphologies of the newly prepared DSSCs were explored using field emission scanning electron microscopy (FE-SEM). Analysis of the FE-SEM images indicate that the DSSC composed of E7 embedded on e-PVdF-co-HFP polymer gel electrolyte has a greatly regular morphology with an average diameter. The ionic conductivity of E7 embedded on e-PVdF-co-HFP polymer gel electrolyte was found to be 2.9 × 10(-3) S/cm at room temperature, a value that is 37% higher than that of e-PVdF-co-HFP polymer gel electrolyte. The DCCS containing the E7 embedded, e-PVdF-co-HFP polymer gel electrolyte was observed to possess a much higher power conversion efficiency (PCE = 6.82%) than that of an e-PVdF-co-HFP nanofiber (6.35%). In addition, DSSCs parameters of the E7 embedded, e-PVdF-co-HFP polymer gel electrolyte (V(oc) = 0.72 V, J(sc) = 14.62 mA/cm(2), FF = 64.8%, and PCE = 6.82% at 1 sun intensity) are comparable to those of a liquid electrolyte (V(oc) = 0.75 V, J(sc) = 14.71 mA/cm(2), FF = 64.9%, and PCE = 7.17%, both at a 1 sun intensity).

  12. Dosimetric properties of N-isopropylacrylamide polymer gel using nonelectrophoresis grade BIS in preparation

    Directory of Open Access Journals (Sweden)

    Roghayeh Khodadadi

    2015-01-01

    Conclusion: Substitution non-electrophoresis grade BIS not only reduces the cost of gel preparation without any adverse effect on its dose response, but also its lower background increases the dynamic range of dose linearity.

  13. SYNTHESIS AND OPTICAL PROPERTIES OF A NOVEL ORGANIC/INORGANIC HYBRID NONLINEAR OPTICAL POLYMER VIA SOL-GEL PROCESS

    Institute of Scientific and Technical Information of China (English)

    Hong-xia Xi; Zhong Li; Zhao-xi Liang

    2001-01-01

    A new organic/inorganic hybrid nonlinear optical (NLO) material was developed by the sol-gel process of an alkoxysilane dye with tetraethoxysilane. A NLO moiety based on 4-nitro-4′-hydroxy azobenzene was covalently bonded to the triethoxysilane derivative, i.e. γ-isocyanatopropyl triethoxysilane. The preparation process and properties of the sol-gel derived NLO polymer were studied and characterized by SEM, FTIR, 1H-NMR, UV-Vis, DSC and second harmonic generation (SHG) measurement. The results indicated that the chemical bonding of the chromophores to the inorganic SiO2 networks induces Iow dipole alignment relaxation and preferable orientational stability. The SHG measurements also showed that the bonded polymer film containing 75 wt% of the akoxysilane dye has a high electro-optic coefficient (r33) of7. 1 pm/V at 1.1 μm wavelength, and exhibit good SHG stability, the r33 values can maintain about 92.7% of its initial value at room temperature for 90 days, and can maintain about 59.3% at 100℃ for 300 min.``

  14. Enhancement of Dose Response and Nuclear Magnetic Resonance Image of PAGAT Polymer Gel Dosimeter by Adding Silver Nanoparticles

    Science.gov (United States)

    Sabbaghizadeh, Rahim; Shamsudin, Roslinda; Deyhimihaghighi, Najmeh; Sedghi, Arman

    2017-01-01

    In the present study, the normoxic polyacrylamide gelatin and tetrakis hydroxy methyl phosphoniun chloride (PAGAT) polymer gel dosimeters were synthesized with and without the presence of silver (Ag) nanoparticles. The amount of Ag nanoparticles varied from 1 to 3 ml with concentration 3.14 g/l, thus forming two types of PAGAT polymer gel dosimeters before irradiating them with 6 to 25 Gy produced by 1.25-MeV 60Co gamma rays. In this range, the predominant gamma ray interaction with matter is by Compton scattering effect, as the photoelectric absorption effect diminishes. MRI was employed when evaluating the polymerization of the dosimeters and the gray scale of the MRI film was determined via an optical densitometer. Subsequent analyses of optical densities revealed that the extent of polymerization increased with the increase in the absorbed dose, while the increase of penetration depth within the dosimeters has a reverse effect. Moreover, a significant increase in the optical density-dose response (11.82%) was noted for dosimeters containing 2 ml Ag nanoparticles. PMID:28060829

  15. Ion- and pH-activated novel in-situ gel system for sustained ocular drug delivery.

    Science.gov (United States)

    Gupta, Himanshu; Velpandian, T; Jain, Sanyog

    2010-08-01

    Poor bioavailability (situ gel system activated by dual physiological mechanisms. Chitosan (a pH-sensitive polymer) in combination with gellan gum (an ion-activated polymer) were used as gelling agent. Timolol maleate, the drug which is frequently used for glaucoma therapy was used as model drug to check the efficacy of the formulation. The developed formulation was characterized for various in vitro parameters, for example, clarity, gelation pH, isotonicity, sterility, viscosity, transcorneal permeation profile, and ocular irritation. Ocular retention was studied by gamma scintigraphy and a significant increase in retention time was observed. The formulation was also found to be nonirritant and well tolerable. The developed system can be a viable alternative to conventional eye drops for the treatment of various ocular diseases and is suitable for clinical application.

  16. Topical anti-inflammatory activity of pinda thailam, a herbal gel formulation.

    Science.gov (United States)

    Periyanayagam, K; Venkatarathnakumar, T; Nagaveni, A; Subitha, V G; Sundari, P; Vaijorohini, M; Umamaheswari, V

    2004-07-01

    The present study aims to evaluate the topical anti-inflammatory activity of "Pinda thailam", a herbal gel formulation containing aqueous extract of roots of Rubia cordifolia (Rubiaceae) and Hemidesmus indicus (Asclepiadaceae) which are known for their anti-inflammatory activity using the technique of carrageenin induced paw oedema in albino rats. The herbal gel formulation showed significant anti-inflammatory activity comparable to the reference standard Diclofenac sodium gel.

  17. Study of hafnium (IV) oxide nanoparticles synthesized by polymerized complex and polymer precursor derived sol-gel methods

    KAUST Repository

    Ramos-González, R.

    2010-03-01

    This work reports the preparation and characterization of hafnium (IV) oxide (HfO2) nanoparticles grown by derived sol-gel routes that involves the formation of an organic polymeric network. A comparison between polymerized complex (PC) and polymer precursor (PP) methods is presented. For the PC method, citric acid (CA) and ethylene glycol (EG) are used as the chelating and polymerizable reagents, respectively. In the case of PP method, poly(acrylic acid) (PAA) is used as the chelating reagent. In both cases, different precursor gels were prepared and the hafnium (IV) chloride (HfCl4) molar ratio was varied from 0.1 to 1.0 for the PC method and from 0.05 to 0.5 for the PP method. In order to obtain the nanoparticles, the precursors were heat treated at 500 and 800 °C. The thermal characterization of the precursor gels was carried out by thermogravimetric analysis (TGA) and the structural and morphological characterization by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD patterns of the samples obtained by both methods shows the formation of HfO2 at 500 °C with monoclinic crystalline phase. The PC method exhibited also the cubic phase. Finally, the HfO2 nanoparticles size (4 to 11 nm) was determined by TEM and XRD patterns. © (2010) Trans Tech Publications.

  18. MRI-based polymer gel dosimetry for validating plans with multiple matrices in Gamma Knife stereotactic radiosurgery.

    Science.gov (United States)

    Gopishankar, N; Watanabe, Yoichi; Subbiah, Vivekanandhan

    2011-01-31

    One of treatment planning techniques with Leksell GammaPlan (LGP) for Gamma Knife stereotactic radiosurgery (GKSRS) uses multiple matrices with multiple dose prescriptions. Computational complexity increases when shots are placed in multiple matrices with different grid sizes. Hence, the experimental validation of LGP calculated dose distributions is needed for those cases. For the current study, we used BANG3 polymer gel contained in a head-sized glass bottle to simulate the entire treatment process of GKSRS. A treatment plan with three 18 mm shots and one 8 mm shot in separate matrices was created with LGP. The prescribed maximum dose was 8 Gy to three shots and 16 Gy to one of the 18 mm shots. The 3D dose distribution recorded in the gel dosimeter was read using a Siemens 3T MRI scanner. The scanning parameters of a CPMG pulse sequence with 32 equidistant echoes were as follows: TR = 7 s, echo step = 13.6 ms, field-of-view = 256 mm × 256 mm, and pixel size = 1 mm × 1 mm. Interleaved acquisition mode was used to obtain 15 to 45 2-mm-thick slices. Using a calibration relationship between absorbed dose and the spin-spin relaxation rate (R2), we converted R2 images to dose images. MATLAB-based in-house programs were used for R2 estimation and dose comparison. Gamma-index analysis for the 3D data showed gamma values less than unity for 86% of the voxels. Through this study we accomplished the first application of polymer gel dosimetry for a true comparison between measured 3D dose distributions and LGP calculations for plans using multiple matrices for multiple targets.

  19. Extracellular polymers of ozonized waste activated sludge.

    Science.gov (United States)

    Liu, J C; Lee, C H; Lai, J Y; Wang, K C; Hsu, Y C; Chang, B V

    2001-01-01

    Effect of ozonation on characteristics of waste activated sludge was investigated in the current study. Concentrations of cell-bound extracellular polymers (washed ECPs) did not change much upon ozonation, whereas the sum of cell-bound and soluble extracellular polymers (unwashed ECPs) increased with increasing ozone dose. Washed ECPs in original sludge as divided by molecular weight distribution was 39% 10,000 Da (high MW). It was observed that the low-MW fraction decreased, and the high-MW fraction increased in ozonized sludge. The unwashed ECPs were characterized as 44% in low MW, 30% in medium MW, and 26% in high MW. Both low-MW and medium-MW fractions of unwashed ECPs decreased while high-MW fraction increased in ozonized sludge. The dewaterability of ozonized sludge, assessed by capillary suction time (CST) and specific resistance to filtration (SRF), deteriorated with ozone dose. The optimal dose of cationic polyelectrolyte increased with increasing ozone dose. The production rate and the accumulated amount of methane gas of ozonized sludge were also higher.

  20. Solid-state electric double layer capacitors fabricated with plastic crystal based flexible gel polymer electrolytes: Effective role of electrolyte anions

    Energy Technology Data Exchange (ETDEWEB)

    Suleman, Mohd; Kumar, Yogesh; Hashmi, S.A., E-mail: sahashmi@physics.du.ac.in

    2015-08-01

    Flexible gel polymer electrolyte (GPE) thick films incorporated with solutions of lithium trifluoromethanesulfonate (Li-triflate or LiTf) and lithium bis trifluoromethane-sulfonimide (LiTFSI) in a plastic crystal succinonitrile (SN), entrapped in poly(vinylidine fluoride-co-hexafluoropropylene) (PVdF-HFP) have been prepared and characterized. The films have been used as electrolytes in the electrical double layer capacitors (EDLCs). Coconut-shell derived activated carbon with high specific surface area (∼2100 m{sup 2} g{sup −1}) and mixed (micro- and meso-) porosity has been used as EDLC electrodes. The structural, thermal, and electrochemical characterization of the GPEs have been performed using scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), impedance measurements and cyclic voltammetry. The high ionic conductivity (∼10{sup −3} S cm{sup −1} at 25 °C), good electrochemical stability window (>4.0 V) and flexible nature of the free-standing films of GPEs show their competence in the fabrication of EDLCs. The EDLCs have been tested using electrochemical impedance spectroscopy, cyclic voltammetry, and charge–discharge studies. The EDLCs using LiTf based electrolyte have been found to give higher values of specific capacitance, specific energy, power density (240–280 F g{sup −1}, ∼39 Wh kg{sup −1} and ∼19 kW kg{sup −1}, respectively) than the EDLC cell with LiTFSI based gel electrolyte. EDLCs have been found to show stable performance for ∼10{sup 4} charge–discharge cycles. The comparative studies indicate the effective role of electrolyte anions on the capacitive performance of the solid-state EDLCs. - Graphical abstract: Display Omitted - Highlights: • Flexible EDLCs with succinonitrile based gel electrolyte membranes are reported. • Anionic size of salts in gel electrolytes plays important role on capacitive performance. • Li-triflate incorporated gel electrolyte shows better

  1. Preconcentration and Determination of Mefenamic Acid in Pharmaceutical and Biological Fluid Samples by Polymer-grafted Silica Gel Solid-phase Extraction Following High Performance Liquid Chromatography

    OpenAIRE

    Bagheri Sadeghi, Hayedeh; Panahi, Homayon Ahmad; Mahabadi, Mahsa; Moniri, Elham

    2015-01-01

    Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) that has analgesic, anti-infammatory and antipyretic actions. It is used to relieve mild to moderate pains. Solid-phase extraction of mefenamic acid by a polymer grafted to silica gel is reported. Poly allyl glycidyl ether/iminodiacetic acid-co-N, N-dimethylacrylamide was synthesized and grafted to silica gel and was used as an adsorbent for extraction of trace mefenamic acid in pharmaceutical and biological samples. Different fa...

  2. High-temperature solvent stability of sol-gel germania triblock polymer coatings in capillary microextraction on-line coupled to high-performance liquid chromatography.

    Science.gov (United States)

    Segro, Scott S; Malik, Abdul

    2010-09-10

    Germania-based sol-gel organic-inorganic hybrid coatings were prepared for on-line coupling of capillary microextraction with high-performance liquid chromatography. For this, a germania-based sol-gel precursor, tetra-n-butoxygermane and a hydroxy-terminated triblock copolymer, poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) were used. These sol-gel germania triblock polymer coatings were chemically anchored to the inner walls of a fused silica capillary (0.25 mm I.D.) in course of its evolution from the sol solution. Scanning electron microscopy images of the sol-gel germania triblock polymer coating were obtained to estimate the coating thickness. For the first time, the analyte distribution constants between a sol-gel germania organic-inorganic hybrid coating and the samples (K(cs)) were determined. For a variety of analytes from different chemical classes, including polycyclic aromatic hydrocarbons (PAHs), ketones, alcohols, phenols and amines, the K(cs) values ranged from 8.1 x 10(1) to 5.6 x 10(4). Also, for the first time, the stability of the sol-gel germania-based coating in high-temperature reversed-phase solvent environment was evaluated. The sol-gel germania triblock polymer coatings were capable of surviving exposure to high-temperature solvent conditions (200 degrees C) with little change in extraction capabilities. This demonstrates that sol-gel germania triblock polymer hybrid materials might be suitable for further applications in high-temperature HPLC. The reproducibility of the method for preparation of the sol-gel germania triblock polymer coatings was also evaluated, and the capillary-to-capillary RSD values ranged from 5.3 to 6.5%. The use of higher flow rates in extraction was found to significantly reduce the time required (from 30-40 to 10-15 min) to reach equilibrium between the sol-gel germania triblock polymer coating and the analytes in the sample solution.

  3. Enhanced conductivity of sol-gel silica cladding for efficient poling in electro-optic polymer/TiO2 vertical slot waveguide modulators.

    Science.gov (United States)

    Enami, Yasufumi; Jouane, Youssef; Luo, Jingdong; Jen, Alex K-Y

    2014-12-01

    We report the enhanced conductivity of sol-gel silica under-cladding for efficient poling of electro-optic (EO) polymer in a hybrid EO polymer/TiO2 vertical slot waveguide modulator. The electrical volume conductivity of sol-gel silica cladding increases approximately 30 times when the calcining time of the cladding layer is critically reduced to 45 minutes, which increases the in-device EO coefficient of the 600-nm-thick EO polymer film in modulators and reduces the lower halfwave voltage (Vπ) of the modulators. The lowest driving voltage (Vπ) of the TiO2 slot waveguide modulator is 2.0 V for an electrode length (Le) of 10 mm and wavelength of 1550 nm (VπLe = 2.0 V·cm) for the low-index guest-host EO polymer SEO125. The optical propagation loss is reduced to 7 dB/cm.

  4. Hydrophobic surface modification of chitosan gels by stearyl for improving the activity of immobilized lipase

    Institute of Scientific and Technical Information of China (English)

    Hong Tao Deng; Juan Juan Wang; Miao Ma; Zhong Yang Liu; Fei Zheng

    2009-01-01

    The hydrophobic surface modification of chitosan gels was carded out using the amidating reaction of amido groups on a gel surface with steafic acid activated by 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC) and N-hydroxy-succinimide (NHS). Lipases from Candida rugosa were adsorbed on the nascent chitosan gels (CS) and stearyl-modified gels (SCS) with different degrees of amidation. The increased surface hydrophobicity of chitosan gels improved the adsorption capacity and activity of the immobilized lipase. SCS with 31.46% amidation showed the maximum activity retention (83.43%). The experimental results suggest that the moderate surface hydrophilicity/hydropbobicity of chitosan gels is necessary for the improvement of the activity of immobilized lipase.

  5. Electrochemical characterizations on MnO2 supercapacitors with potassium polyacrylate and potassium polyacrylate-co-polyacrylamide gel polymer electrolytes

    KAUST Repository

    Lee, Kuang-Tsin

    2009-11-01

    MnO2·nH2O supercapacitors with potassium polyacrylate (PAAK) and potassium polyacrylate-co-polyacrylamide (PAAK-co-PAAM) gel polymer electrolytes (GPEs) having the weight compositions of polymer:KCl:H2O = 9%:6.7%:84.3% have been characterized for their electrochemical performance. Compared with the liquid electrolyte (LE) counterpart, the GPE cells exhibit remarkable (∼50-130%) enhancement in specific capacitance of the oxide electrode, and the extent of the enhancement increases with increasing amount of the carboxylate groups in the polymers as well as with increasing oxide/electrolyte interfacial area. In situ X-ray absorption near-edge structure (XANES) analysis indicates that the oxide electrodes of the GPE cells possess higher Mn-ion valences and are subjected to greater extent of valence variation than that of the LE cell upon charging/discharging over the same potential range. Copolymerization of PAAK with PAAM greatly improves the cycling stability of the MnO2·nH2O electrode, and the improvement is attributable to the alkaline nature of the amino groups. Both GPEs exhibit ionic conductivities greater than 1.0 × 10-1 S cm-1 and are promising for high-rate applications. © 2009 Elsevier Ltd. All rights reserved.

  6. Note: Utilization of polymer gel as a bolus compensator and a dosimeter in the near-surface buildup region for breast-conserving therapy

    Energy Technology Data Exchange (ETDEWEB)

    Fuse, Hiraku, E-mail: fuseh@ipu.ac.jp; Inohira, Masaya; Kawamura, Hiraku; Fujisaki, Tatsuya [Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, Inashiki-gun, Ibaraki 300-0331 (Japan); Shinoda, Kazuya [Graduate School of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, Ibaraki (Japan); Department of Radiological Technology, Tsukuba Medical Center Hospital, Tsukuba (Japan); Miyamoto, Katsumi [Department of Radiological Technology, Tsukuba Medical Center Hospital, Tsukuba (Japan); Sakae, Takeji [Faculty of Medicine, University of Tsukuba, Tsukuba (Japan)

    2015-09-15

    Tangential beam radiotherapy is routinely used for radiation therapy after breast conserving surgery. A tissue-equivalent bolus placed on the irradiated area shifts the depth of the dose distribution; this bolus provides uniform dose distribution to the breast. The gel bolus made by the BANG-Pro{sup ®} polymer gel and in an oxygen non-transmission pack was applicable as a dosimeter to measure dose distribution in near-surface buildup region. We validated the use of the gel bolus to improve in the whole-breast/chest wall, including the near-surface buildup region.

  7. UV-cured methacrylic membranes as novel gel-polymer electrolyte for Li-ion batteries

    Science.gov (United States)

    Nair, J. R.; Gerbaldi, C.; Meligrana, G.; Bongiovanni, R.; Bodoardo, S.; Penazzi, N.; Reale, P.; Gentili, V.

    In this paper, we report the synthesis and characterisation of novel methacrylic based polymer electrolyte membranes for lithium batteries. The method adopted for preparing the solid polymer electrolyte was the UV-curing process, which is well known for being easy, low cost, fast and reliable. It consists of a free radical photo polymerisation of poly-functional monomers: Bisphenol A ethoxylate (15 EO/phenol) dimethacrylate (BEMA) was chosen, as it can readily form flexible 3D networks and has long poly-ethoxy chains which can enhance the movement of Li +-ions inside the polymer matrix. The preliminary results reported here refer to systems where LiPF 6 solutions swelled the preformed polymer membranes. The tests on the conductivity, stability and cyclability of the membranes put in evidence the importance of the polymerisation in presence of mono-methacrylates acting as reactive diluents. Good values of ionic conductivity have been found, especially at ambient temperature. Much better results can be expected by choosing an appropriate mono-methacrylate to modify the polymeric membrane properties and by modifying the methodology of Li +-ions incorporation inside the polymer matrix.

  8. Multiple patterns of polymer gels in microspheres due to the interplay among phase separation, wetting, and gelation.

    Science.gov (United States)

    Yanagisawa, Miho; Nigorikawa, Shinpei; Sakaue, Takahiro; Fujiwara, Kei; Tokita, Masayuki

    2014-11-11

    We report the spontaneous patterning of polymer microgels by confining a polymer blend within microspheres. A poly(ethylene glycol) (PEG) and gelatin solution was confined inside water-in-oil (W/O) microdroplets coated with a layer of zwitterionic lipids: dioleoylphosphatidylethanolamine (PE) and dioleoylphosphatidylcholine (PC). The droplet confinement affected the kinetics of the phase separation, wetting, and gelation after a temperature quench, which determined the final microgel pattern. The gelatin-rich phase completely wetted to the PE membrane and formed a hollow microcapsule as a stable state in the PE droplets. Gelation during phase separation varied the relation between the droplet size and thickness of the capsule wall. In the case of the PC droplets, phase separation was completed only for the smaller droplets, wherein the microgel partially wetted the PC membrane and had a hemisphere shape. In addition, the temperature decrease below the gelation point increased the interfacial tension between the PEG/gelatin phases and triggered a dewetting transition. Interestingly, the accompanying shape deformation to minimize the interfacial area was only observed for the smaller PC droplets. The critical size decreased as the gelatin concentration increased, indicating the role of the gel elasticity as an inhibitor of the deformation. Furthermore, variously patterned microgels with spherically asymmetric shapes, such as discs and stars, were produced as kinetically trapped states by regulating the incubation time, polymer composition, and droplet size. These findings demonstrate a way to regulate the complex shapes of microgels using the interplay among phase separation, wetting, and gelation of confined polymer blends in microdroplets.

  9. RapidArc treatment verification in 3D using polymer gel dosimetry and Monte Carlo simulation

    DEFF Research Database (Denmark)

    Ceberg, Sofie; Gagne, Isabel; Gustafsson, Helen

    2010-01-01

    arc rotation and a target dose of 3.3 Gy. Magnetic resonance imaging of the gel was carried out using a 1.5 T scanner. The MC dose distributions were calculated using the VIMC-Arc code. The relative absorbed dose differences were calculated voxel-by-voxel, within the volume enclosed by the 90% isodose...

  10. Tomotherapy dose distribution verification using MAGIC-f polymer gel dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Pavoni, J. F.; Pike, T. L.; Snow, J.; DeWerd, L.; Baffa, O. [Departamento de Fisica, Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto-Universidade de Sao Paulo, Av. Bandeirantes, 3900 - CEP 14040-901 - Bairro Monte Alegre - Ribeirao Preto, SP (Brazil); Medical Radiation Research Center, Department of Medical Physics, University of Wisconsin, 1111 Highland Avenue, B1002 WIMR, Madison, Wisconsin 53705-2275 (United States); Departamento de Fisica, Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto-Universidade de Sao Paulo, Av. Bandeirantes, 3900 - CEP 14040-901 - Bairro Monte Alegre - Ribeirao Preto, SP (Brazil)

    2012-05-15

    Purpose: This paper presents the application of MAGIC-f gel in a three-dimensional dose distribution measurement and its ability to accurately measure the dose distribution from a tomotherapy unit. Methods: A prostate intensity-modulated radiation therapy (IMRT) irradiation was simulated in the gel phantom and the treatment was delivered by a TomoTherapy equipment. Dose distribution was evaluated by the R2 distribution measured in magnetic resonance imaging. Results: A high similarity was found by overlapping of isodoses of the dose distribution measured with the gel and expected by the treatment planning system (TPS). Another analysis was done by comparing the relative absorbed dose profiles in the measured and in the expected dose distributions extracted along indicated lines of the volume and the results were also in agreement. The gamma index analysis was also applied to the data and a high pass rate was achieved (88.4% for analysis using 3%/3 mm and of 96.5% using 4%/4 mm). The real three-dimensional analysis compared the dose-volume histograms measured for the planning volumes and expected by the treatment planning, being the results also in good agreement by the overlapping of the curves. Conclusions: These results show that MAGIC-f gel is a promise for tridimensional dose distribution measurements.

  11. Graphene tailored polymer gel electrolytes for 9.1%-efficiency quasi-solid-state dye-sensitized solar cells

    Science.gov (United States)

    Zheng, Jingjing

    2017-04-01

    Pursuit of technological implementation with enhanced photoelectric conversion efficiency and power generation ability in the dark is a persistent objective for dye-sensitized solar cells (DSSCs). We launch here three strategies of designing graphene tailored polymer gel electrolytes (PGEs) with an electron-conducting feature, aiming at reserving I-/I3- redox couples into three-dimensional (3D) PGE framework, reducing I3- species within the PGE and shortening the diffusion length of redox couples. The 3D PGE provides framework for I-/I3- diffusion like in a liquid system, whereas graphene experiences to form interconnected channels along polyelectrolyte backbones. The results demonstrate that a power conversion efficiency of 9.1% is yielded on the resultant quasi-solid-state DSSCs by optimizing synthesis strategies.

  12. Gel polymer electrolyte based on LiBOB and PAN for the application in dye-sensitized solar cells

    Science.gov (United States)

    Arof, A. K.; Jun, H. K.; Sim, L. N.; Kufian, M. Z.; Sahraoui, B.

    2013-11-01

    Dye-sensitized solar cells (DSSCs) have been fabricated using metal complex N3 dye coupled with LiBOB and PAN-based gel polymer electrolyte (GPE). Conductivity of the GPE at room temperature was 1.2 × 10-2 S cm-1. The deconvoluted vibration spectra at different temperatures between 1000 and 970 cm-1 show the existence of ion pairs and free ions. Overall efficiency and fill factor of the DSSC with LiBOB-BMII-PAN-I2 GPE system is 0.65% and 48% respectively. The cell with LiBOB-BMII-PAN-I2 GPE system appears to be stable under varied light intensity attributed to the presence of redox couple mediator in the GPE. Impedance measurements show that the DSSC with LiBOB-BMII-PAN-I2 GPE has longer electron lifetime which suggests a lower electron recombination rate.

  13. A pH-responsive supramolecular polymer gel as an enteric elastomer for use in gastric devices.

    Science.gov (United States)

    Zhang, Shiyi; Bellinger, Andrew M; Glettig, Dean L; Barman, Ross; Lee, Young-Ah Lucy; Zhu, Jiahua; Cleveland, Cody; Montgomery, Veronica A; Gu, Li; Nash, Landon D; Maitland, Duncan J; Langer, Robert; Traverso, Giovanni

    2015-10-01

    Devices resident in the stomach-used for a variety of clinical applications including nutritional modulation for bariatrics, ingestible electronics for diagnosis and monitoring, and gastric-retentive dosage forms for prolonged drug delivery-typically incorporate elastic polymers to compress the devices during delivery through the oesophagus and other narrow orifices in the digestive system. However, in the event of accidental device fracture or migration, the non-degradable nature of these materials risks intestinal obstruction. Here, we show that an elastic, pH-responsive supramolecular gel remains stable and elastic in the acidic environment of the stomach but can be dissolved in the neutral-pH environment of the small and large intestines. In a large animal model, prototype devices with these materials as the key component demonstrated prolonged gastric retention and safe passage. These enteric elastomers should increase the safety profile for a wide range of gastric-retentive devices.

  14. ACTIVE INTERMEDIATES IN PHOTORADICAL AGING OF POLYMERS

    Institute of Scientific and Technical Information of China (English)

    M.Ya. Mel'nikov

    2001-01-01

    The data referring to the mechanism and efficiency of electronically excited macroradical and radical anion reactions, the important role of photochemical chain reactions in polymers are presented. It was found that by varying photon energy, temperature, photolysis time and competition between thermal and photochemical reactions, it is possible to change the functional composition and molecular weight distribution of polymers.

  15. Performance Characterization of a Lithium-ion Gel Polymer Battery Power Supply System for an Unmanned Aerial Vehicle

    Science.gov (United States)

    Reid, Concha M.; Manzo, Michelle A.; Logan, Michael J.

    2004-01-01

    Unmanned aerial vehicles (UAVs) are currently under development for NASA missions, earth sciences, aeronautics, the military, and commercial applications. The design of an all electric power and propulsion system for small UAVs was the focus of a detailed study. Currently, many of these small vehicles are powered by primary (nonrechargeable) lithium-based batteries. While this type of battery is capable of satisfying some of the mission needs, a secondary (rechargeable) battery power supply system that can provide the same functionality as the current system at the same or lower system mass and volume is desired. A study of commercially available secondary battery cell technologies that could provide the desired performance characteristics was performed. Due to the strict mass limitations and wide operating temperature requirements of small UAVs, the only viable cell chemistries were determined to be lithium-ion liquid electrolyte systems and lithium-ion gel polymer electrolyte systems. Two lithium-ion gel polymer cell designs were selected as candidates and were tested using potential load profiles for UAV applications. Because lithium primary batteries have a higher specific energy and energy density, for the same mass and volume allocation, the secondary batteries resulted in shorter flight times than the primary batteries typically provide. When the batteries were operated at lower ambient temperatures (0 to -20 C), flight times were even further reduced. Despite the reduced flight times demonstrated, for certain UAV applications, the secondary batteries operated within the acceptable range of flight times at room temperature and above. The results of this testing indicate that a secondary battery power supply system can provide some benefits over the primary battery power supply system. A UAV can be operated for hundreds of flights using a secondary battery power supply system that provides the combined benefits of rechargeability and an inherently safer

  16. Investigation of a 2D two-point maximum entropy regularization method for signal-to-noise ratio enhancement: application to CT polymer gel dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Jirasek, A [Department of Physics and Astronomy, University of Victoria, Victoria BC V8W 3P6 (Canada); Matthews, Q [Department of Physics and Astronomy, University of Victoria, Victoria BC V8W 3P6 (Canada); Hilts, M [Medical Physics, BC Cancer Agency-Vancouver Island Centre, Victoria BC V8R 6V5 (Canada); Schulze, G [Michael Smith Laboratories, University of British Columbia, Vancouver BC V6T 1Z4 (Canada); Blades, M W [Department of Chemistry, University of British Columbia, Vancouver BC V6T 1Z1 (Canada); Turner, R F B [Michael Smith Laboratories, University of British Columbia, Vancouver BC V6T 1Z4 (Canada); Department of Chemistry, University of British Columbia, Vancouver BC V6T 1Z1 (Canada); Department of Electrical and Computer Engineering, University of British Columbia, Vancouver BC V6T 1Z4 (Canada)

    2006-05-21

    This study presents a new method of image signal-to-noise ratio (SNR) enhancement by utilizing a newly developed 2D two-point maximum entropy regularization method (TPMEM). When utilized as an image filter, it is shown that 2D TPMEM offers unsurpassed flexibility in its ability to balance the complementary requirements of image smoothness and fidelity. The technique is evaluated for use in the enhancement of x-ray computed tomography (CT) images of irradiated polymer gels used in radiation dosimetry. We utilize a range of statistical parameters (e.g. root-mean square error, correlation coefficient, error histograms, Fourier data) to characterize the performance of TPMEM applied to a series of synthetic images of varying initial SNR. These images are designed to mimic a range of dose intensity patterns that would occur in x-ray CT polymer gel radiation dosimetry. Analysis is extended to a CT image of a polymer gel dosimeter irradiated with a stereotactic radiation therapy dose distribution. Results indicate that TPMEM performs strikingly well on radiation dosimetry data, significantly enhancing the SNR of noise-corrupted images (SNR enhancement factors >15 are possible) while minimally distorting the original image detail (as shown by the error histograms and Fourier data). It is also noted that application of this new TPMEM filter is not restricted exclusively to x-ray CT polymer gel dosimetry image data but can in future be extended to a wide range of radiation dosimetry data.

  17. Investigation of a 2D two-point maximum entropy regularization method for signal-to-noise ratio enhancement: application to CT polymer gel dosimetry.

    Science.gov (United States)

    Jirasek, A; Matthews, Q; Hilts, M; Schulze, G; Blades, M W; Turner, R F B

    2006-05-21

    This study presents a new method of image signal-to-noise ratio (SNR) enhancement by utilizing a newly developed 2D two-point maximum entropy regularization method (TPMEM). When utilized as an image filter, it is shown that 2D TPMEM offers unsurpassed flexibility in its ability to balance the complementary requirements of image smoothness and fidelity. The technique is evaluated for use in the enhancement of x-ray computed tomography (CT) images of irradiated polymer gels used in radiation dosimetry. We utilize a range of statistical parameters (e.g. root-mean square error, correlation coefficient, error histograms, Fourier data) to characterize the performance of TPMEM applied to a series of synthetic images of varying initial SNR. These images are designed to mimic a range of dose intensity patterns that would occur in x-ray CT polymer gel radiation dosimetry. Analysis is extended to a CT image of a polymer gel dosimeter irradiated with a stereotactic radiation therapy dose distribution. Results indicate that TPMEM performs strikingly well on radiation dosimetry data, significantly enhancing the SNR of noise-corrupted images (SNR enhancement factors >15 are possible) while minimally distorting the original image detail (as shown by the error histograms and Fourier data). It is also noted that application of this new TPMEM filter is not restricted exclusively to x-ray CT polymer gel dosimetry image data but can in future be extended to a wide range of radiation dosimetry data.

  18. Effective Infiltration of Gel Polymer Electrolyte into Silicon-Coated Vertically Aligned Carbon Nanofibers as Anodes for Solid-State Lithium-Ion Batteries.

    Science.gov (United States)

    Pandey, Gaind P; Klankowski, Steven A; Li, Yonghui; Sun, Xiuzhi Susan; Wu, Judy; Rojeski, Ronald A; Li, Jun

    2015-09-23

    This study demonstrates the full infiltration of gel polymer electrolyte into silicon-coated vertically aligned carbon nanofibers (Si-VACNFs), a high-capacity 3D nanostructured anode, and the electrochemical characterization of its properties as an effective electrolyte/separator for future all-solid-state lithium-ion batteries. Two fabrication methods have been employed to form a stable interface between the gel polymer electrolyte and the Si-VACNF anode. In the first method, the drop-casted gel polymer electrolyte is able to fully infiltrate into the open space between the vertically aligned core-shell nanofibers and encapsulate/stabilize each individual nanofiber in the polymer matrix. The 3D nanostructured Si-VACNF anode shows a very high capacity of 3450 mAh g(-1) at C/10.5 (or 0.36 A g(-1)) rate and 1732 mAh g(-1) at 1C (or 3.8 A g(-1)) rate. In the second method, a preformed gel electrolyte film is sandwiched between an Si-VACNF electrode and a Li foil to form a half-cell. Most of the vertical core-shell nanofibers of the Si-VACNF anode are able to penetrate into the gel polymer film while retaining their structural integrity. The slightly lower capacity of 2800 mAh g(-1) at C/11 rate and ∼1070 mAh g(-1) at C/1.5 (or 2.6 A g(-1)) rate have been obtained, with almost no capacity fade for up to 100 cycles. Electrochemical impedance spectroscopy does not show noticeable changes after 110 cycles, further revealing the stable interface between the gel polymer electrolyte and the Si-VACNFs anode. These results show that the infiltrated flexible gel polymer electrolyte can effectively accommodate the stress/strain of the Si shell due to the large volume expansion/contraction during the charge-discharge processes, which is particularly useful for developing future flexible solid-state lithium-ion batteries incorporating Si-anodes.

  19. An ion-imprinted polymer supported by attapulgite with a chitosan incorporated sol-gel process for selective separation of Ce(Ⅲ)

    Institute of Scientific and Technical Information of China (English)

    Chun Xiang Li; Jian Ming Pan; Jie Gao; Yong Sheng Yan; Gan Qing Zhao

    2009-01-01

    The surface ion-imprinting concept and chitosan incorporated sol-gel process were applied to the synthesis of a new attapulgite-supported polymer for selective separation of Ce(Ⅲ) from aqueous solution. The imprinting mechanism of prepared ion-imprinted polymer were discussed with the Characteristics of FT-IR and SEM. Results from the experiments of adsorption capacity and selectivity suggested that ion-imprinted polymer offered a fast kinetics for the adsorption of Ce(Ⅲ) under the optimum conditions. Its maximum adsorption capacity was 38.02 mg/g, and the selective recognition towards Ce(Ⅲ) was much higher than that of the non-imprinted polymer and attapulgite. The prepared functional polymer was shown to be promising for selective separation and enrichment of trace Ce(Ⅲ) in environmental samples.

  20. Sol-Gel Material-Enabled Electro-Optic Polymer Modulators.

    Science.gov (United States)

    Himmelhuber, Roland; Norwood, Robert A; Enami, Yasufumi; Peyghambarian, Nasser

    2015-07-27

    Sol-gels are an important material class, as they provide easy modification of material properties, good processability and are easy to synthesize. In general, an electro-optic (EO) modulator transforms an electrical signal into an optical signal. The incoming electrical signal is most commonly information encoded in a voltage change. This voltage change is then transformed into either a phase change or an intensity change in the light signal. The less voltage needed to drive the modulator and the lower the optical loss, the higher the link gain and, therefore, the better the performance of the modulator. In this review, we will show how sol-gels can be used to enhance the performance of electro-optic modulators by allowing for designs with low optical loss, increased poling efficiency and manipulation of the electric field used for driving the modulator. The optical loss is influenced by the propagation loss in the device, as well as the losses occurring during fiber coupling in and out of the device. In both cases, the use of sol-gel materials can be beneficial due to the wide range of available refractive indices and low optical attenuation. The influence of material properties and synthesis conditions on the device performance will be discussed.

  1. Sol-Gel Material-Enabled Electro-Optic Polymer Modulators

    Directory of Open Access Journals (Sweden)

    Roland Himmelhuber

    2015-07-01

    Full Text Available Sol-gels are an important material class, as they provide easy modification of material properties, good processability and are easy to synthesize. In general, an electro-optic (EO modulator transforms an electrical signal into an optical signal. The incoming electrical signal is most commonly information encoded in a voltage change. This voltage change is then transformed into either a phase change or an intensity change in the light signal. The less voltage needed to drive the modulator and the lower the optical loss, the higher the link gain and, therefore, the better the performance of the modulator. In this review, we will show how sol-gels can be used to enhance the performance of electro-optic modulators by allowing for designs with low optical loss, increased poling efficiency and manipulation of the electric field used for driving the modulator. The optical loss is influenced by the propagation loss in the device, as well as the losses occurring during fiber coupling in and out of the device. In both cases, the use of sol-gel materials can be beneficial due to the wide range of available refractive indices and low optical attenuation. The influence of material properties and synthesis conditions on the device performance will be discussed.

  2. 3-V Solid-State Flexible Supercapacitors with Ionic-Liquid-Based Polymer Gel Electrolyte for AC Line Filtering.

    Science.gov (United States)

    Kang, Yu Jin; Yoo, Yongju; Kim, Woong

    2016-06-08

    State-of-the-art solid-state flexible supercapacitors with sufficiently fast response speed for AC line filtering application suffer from limited energy density. One of the main causes of the low energy density is the low cell voltage (1 V), which is limited by aqueous-solution-based gel electrolytes. In this work, we demonstrate for the first time a 3-V flexible supercapacitor for AC line filtering based on an ionic-liquid-based polymer gel electrolyte and carbon nanotube electrode material. The flexible supercapacitor exhibits an areal energy density that is more than 20 times higher than that of the previously demonstrated 1-V flexible supercapacitor (0.66 vs 0.03 μWh/cm(2)) while maintaining excellent capacitive behavior at 120 Hz. The supercapacitor shows a maximum areal power density of 1.5 W/cm(2) and a time constant of 1 ms. The improvement of the cell voltage while maintaining the fast-response capability greatly improves the potential of supercapacitors for high-frequency applications in wearable and/or portable electronics.

  3. Composite Gel Polymer Electrolyte Based on Poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) with Modified Aluminum-Doped Lithium Lanthanum Titanate (A-LLTO) for High-Performance Lithium Rechargeable Batteries.

    Science.gov (United States)

    Le, Hang T T; Ngo, Duc Tung; Kalubarme, Ramchandra S; Cao, Guozhong; Park, Choong-Nyeon; Park, Chan-Jin

    2016-08-17

    A composite gel polymer electrolyte (CGPE) based on poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) polymer that includes Al-doped Li0.33La0.56TiO3 (A-LLTO) particles covered with a modified SiO2 (m-SiO2) layer was fabricated through a simple solution-casting method followed by activation in a liquid electrolyte. The obtained CGPE possessed high ionic conductivity, a large electrochemical stability window, and interfacial stability-all superior to that of the pure gel polymer electrolyte (GPE). In addition, under a highly polarized condition, the CGPE effectively suppressed the growth of Li dendrites due to the improved hardness of the GPE by the addition of inorganic A-LLTO/m-SiO2 particles. Accordingly, the Li-ion polymer and Li-O2 cells employing the CGPE exhibited remarkably improved cyclability compared to cells without CGPE. In particular, the CGPE as a protection layer for the Li metal electrode in a Li-O2 cell was effective in blocking the contamination of the Li electrode by oxygen gas or impurities diffused from the cathode side while suppressing the Li dendrites.

  4. Preparation and adsorption behavior of berberine hydrochloride imprinted polymers by using silica gel as sacrificed support material

    Science.gov (United States)

    Li, Hui; Li, Yuzhuo; Li, Zhiping; Peng, Xiyang; Li, Yanan; Li, Gui; Tan, Xianzhou; Chen, Gongxi

    2012-03-01

    Preparation of berberine hydrochloride (B-Cl) imprinted polymers (MIPs) based on surface imprinting technique with silica gel as sacrificial support material was performed successfully by using B-Cl as template, methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) as functional monomer and cross-linker, respectively. The prepared polymers were characterized by Fourier transmission infrared spectrometry (FTIR) and scanning electron microscopy (SEM). Adsorption behavior of the MIPs for the template and its structural analogues was investigated. Sites distribution on the surface of MIPs was explored by using different isotherm adsorption models and thermodynamic parameters for the adsorption of B-Cl on the MIPs determined. Sample application and reusability for the MIPs was also evaluated. Results indicated the strong adsorption and high selectivity of the MIPs for B-Cl. Saturated adsorption capacity reached 27.2 μmol g-1 and the selectivity coefficient of the MIPs for B-Cl relative to jatrorrhizine hydrochloride (J-Cl) and palmatine palmatus hydrochloride (P-Cl) are 3.70 and 6.03, respectively. In addition, the MIPs were shown with good reusability and selectively retention ability in sample application.

  5. Preparation and adsorption behavior of berberine hydrochloride imprinted polymers by using silica gel as sacrificed support material

    Energy Technology Data Exchange (ETDEWEB)

    Li Hui, E-mail: lihuijsdx@163.com [Key Laboratory of Plant Resource Conservation and Utilization, Jishou University, Hunan Jishou, 416000 (China); Li Yuzhuo [Key Laboratory of Plant Resource Conservation and Utilization, Jishou University, Hunan Jishou, 416000 (China); Li Zhiping [College of Chemistry and Chemical Engineering, Jishou University, Hunan Jishou, 416000 (China); Peng Xiyang; Li Yanan; Li Gui; Tan Xianzhou; Chen Gongxi [Key Laboratory of Plant Resource Conservation and Utilization, Jishou University, Hunan Jishou, 416000 (China)

    2012-03-01

    Preparation of berberine hydrochloride (B-Cl) imprinted polymers (MIPs) based on surface imprinting technique with silica gel as sacrificial support material was performed successfully by using B-Cl as template, methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) as functional monomer and cross-linker, respectively. The prepared polymers were characterized by Fourier transmission infrared spectrometry (FTIR) and scanning electron microscopy (SEM). Adsorption behavior of the MIPs for the template and its structural analogues was investigated. Sites distribution on the surface of MIPs was explored by using different isotherm adsorption models and thermodynamic parameters for the adsorption of B-Cl on the MIPs determined. Sample application and reusability for the MIPs was also evaluated. Results indicated the strong adsorption and high selectivity of the MIPs for B-Cl. Saturated adsorption capacity reached 27.2 {mu}mol g{sup -1} and the selectivity coefficient of the MIPs for B-Cl relative to jatrorrhizine hydrochloride (J-Cl) and palmatine palmatus hydrochloride (P-Cl) are 3.70 and 6.03, respectively. In addition, the MIPs were shown with good reusability and selectively retention ability in sample application.

  6. A novel lithium/sulfur battery based on sulfur/graphene nanosheet composite cathode and gel polymer electrolyte.

    Science.gov (United States)

    Zhang, Yongguang; Zhao, Yan; Bakenov, Zhumabay

    2014-03-21

    A novel sulfur/graphene nanosheet (S/GNS) composite was prepared via a simple ball milling of sulfur with commercial multi-layer graphene nanosheet, followed by a heat treatment. High-resolution transmission and scanning electronic microscopy observations showed the formation of irregularly interlaced nanosheet-like structure consisting of graphene with uniform sulfur coating on its surface. The electrochemical properties of the resulting composite cathode were investigated in a lithium cell with a gel polymer electrolyte (GPE) prepared by trapping 1 mol dm-3 solution of lithium bistrifluoromethanesulfonamide in tetraethylene glycol dimethyl ether in a polymer matrix composed of poly(vinylidene fluoride-co-hexafluoropropylene)/poly(methylmethacrylate)/silicon dioxide (PVDF-HFP/PMMA/SiO2). The GPE battery delivered reversible discharge capacities of 809 and 413 mAh g-1 at the 1st and 50th cycles at 0.2C, respectively, along with a high coulombic efficiency over 50 cycles. This performance enhancement of the cell was attributed to the suppression of the polysulfide shuttle effect by a collective effect of S/GNS composite cathode and GPE, providing a higher sulfur utilization.

  7. A novel lithium/sulfur battery based on sulfur/graphene nanosheet composite cathode and gel polymer electrolyte

    Science.gov (United States)

    Zhang, Yongguang; Zhao, Yan; Bakenov, Zhumabay

    2014-03-01

    A novel sulfur/graphene nanosheet (S/GNS) composite was prepared via a simple ball milling of sulfur with commercial multi-layer graphene nanosheet, followed by a heat treatment. High-resolution transmission and scanning electronic microscopy observations showed the formation of irregularly interlaced nanosheet-like structure consisting of graphene with uniform sulfur coating on its surface. The electrochemical properties of the resulting composite cathode were investigated in a lithium cell with a gel polymer electrolyte (GPE) prepared by trapping 1 mol dm-3 solution of lithium bistrifluoromethanesulfonamide in tetraethylene glycol dimethyl ether in a polymer matrix composed of poly(vinylidene fluoride-co-hexafluoropropylene)/poly(methylmethacrylate)/silicon dioxide (PVDF-HFP/PMMA/SiO2). The GPE battery delivered reversible discharge capacities of 809 and 413 mAh g-1 at the 1st and 50th cycles at 0.2C, respectively, along with a high coulombic efficiency over 50 cycles. This performance enhancement of the cell was attributed to the suppression of the polysulfide shuttle effect by a collective effect of S/GNS composite cathode and GPE, providing a higher sulfur utilization. PACS: 82.47.Aa; 82.45.Gj; 62.23.Kn

  8. Improvement of N-phthaloylchitosan based gel polymer electrolyte in dye-sensitized solar cells using a binary salt system.

    Science.gov (United States)

    Yusuf, S N F; Azzahari, A D; Selvanathan, V; Yahya, R; Careem, M A; Arof, A K

    2017-02-10

    A binary salt system utilizing lithium iodide (LiI) as the auxiliary component has been introduced to the N-phthaloylchitosan (PhCh) based gel polymer electrolyte consisting of ethylene carbonate (EC), dimethylformamide (DMF), tetrapropylammonium iodide (TPAI), and iodine (I2) in order to improve the performance of dye-sensitized solar cell (DSSC) with efficiency of 6.36%, photocurrent density, JSC of 17.29mAcm(-2), open circuit voltage, VOC of 0.59V and fill factor, FF of 0.62. This efficiency value is an improvement from the 5.00% performance obtained by the DSSC consisting of only TPAI single salt system. The presence of the LiI in addition to the TPAI improves the charge injection rates and increases the iodide contribution to the total conductivity and both factors contribute to the increase in efficiency of the DSSC. The interaction behavior between polymer-plasticizer-salt was thoroughly investigated using EIS, FTIR spectroscopy and XRD.

  9. Synthesis of Silica Nanoparticles by Sol-Gel: Size-Dependent Properties, Surface Modification, and Applications in Silica-Polymer Nanocomposites—A Review

    Directory of Open Access Journals (Sweden)

    Ismail Ab Rahman

    2012-01-01

    Full Text Available Application of silica nanoparticles as fillers in the preparation of nanocomposite of polymers has drawn much attention, due to the increased demand for new materials with improved thermal, mechanical, physical, and chemical properties. Recent developments in the synthesis of monodispersed, narrow-size distribution of nanoparticles by sol-gel method provide significant boost to development of silica-polymer nanocomposites. This paper is written by emphasizing on the synthesis of silica nanoparticles, characterization on size-dependent properties, and surface modification for the preparation of homogeneous nanocomposites, generally by sol-gel technique. The effect of nanosilica on the properties of various types of silica-polymer composites is also summarized.

  10. SU-E-T-318: Dosimetric Evaluation of ArcCHECK and 3DVH System Using Customized Polymer Gel Dosimeter

    Energy Technology Data Exchange (ETDEWEB)

    Ono, K; Fujimoto, S; Akagi, Y; Hirokawa, Y [Hiroshima Heiwa Clinic, Hiroshima, JP (Japan); Hayashi, S [Hiroshima International University, Hiroshima, JP (Japan); Miyazawa, M [R-TECH.INC, Tokyo, JP (Japan)

    2015-06-15

    Purpose: ArcCHECK and 3DVH system (Sun Nuclear) can reconstruct the three-dimensional (3D) dose distribution and provide the DVH analysis in a patient. The aim of this study was to evaluate dosimetric accuracy of this system using customized polymer gel dosimeter, and also Gafchromic EBT3 films. Methods: Polyacrylamide-based gel contained magnesium chloride as a sensitizer (iPAGAT) was used in this study. Volumetric-modulated arc therapy (VMAT) plan was performed for the C-shape structure by the Eclipse treatment planning system (Varian) and used to irradiate the ArcCHECK by the Novalis Tx linear accelerator (Varian/BrainLAB). The cubic phantom filled with iPAGAT and EBT3 films placed in three orthogonal planes (axial, sagittal, and coronal) inserted into the I’mRT Phantom (IBA Dosimetry) simulated a patient were irradiated with the same VMAT plan. The measurement-guided 3D dose distribution was reconstructed using 3DVH software from the measured data of the ArcCHECK. The 3D dose distribution in iPAGAT was read out by Signa 1.5 T MRI system (GE), and 2D dose distribution on EBT3 was read out by color scanner (Epson). The comparison of all the dose distributions was performed with dose profiles and gamma index analysis in orthogonal planes using in-house developed software. Results: A good agreement was observed by overlaying the dose profiles of 3DVH, EBT3, and iPAGAT. The mean pass rates by gamma index analysis with 3%/3 mm criteria in orthogonal planes were 94.3% (3DVH vs EBT3), 91.1% (3DVH vs iPAGAT), and 96.4% (iPAGAT vs EBT3), respectively. Conclusion: 3D dose distribution reconstructed by ArcCHECK and 3DVH system was estimated accurately in a patient. However, slightly differences were observed between 3DVH and iPAGAT because of MRI noise, therefore further study is required to improve the accuracy of MRI based polymer gel dosimetry for the DVH analysis.

  11. Electromechanically active polymer transducers: research in Europe

    Science.gov (United States)

    Carpi, Federico; Graz, Ingrid; Jager, Edwin; Ladegaard Skov, Anne; Vidal, Frédéric

    2013-10-01

    Smart materials and structures based on electromechanically active polymers (EAPs) represent a fast growing and stimulating field of research and development. EAPs are materials capable of changing dimensions and/or shape in response to suitable electrical stimuli. They are commonly classified in two major families: ionic EAPs (activated by an electrically induced transport of ions and/or solvent) and electronic EAPs (activated by electrostatic forces). These polymers show interesting properties, such as sizable active strains and/or stresses in response to electrical driving, high mechanical flexibility, low density, structural simplicity, ease of processing and scalability, no acoustic noise and, in most cases, low costs. Since many of these characteristics can also describe natural muscle tissues from an engineering standpoint, it is not surprising that EAP transducers are sometimes also referred to as 'muscle-like smart materials' or 'artificial muscles'. They are used not only to generate motion, but also to sense or harvest energy from it. In particular, EAP electromechanical transducers are studied for applications that can benefit from their 'biomimetic' characteristics, with possible usages from the micro- to the macro-scale, spanning several disciplines, such as mechatronics, robotics, automation, biotechnology and biomedical engineering, haptics, fluidics, optics and acoustics. Currently, the EAP field is just undergoing its initial transition from academic research into commercialization, with companies starting to invest in this technology and the first products appearing on the market. This focus issue is intentionally aimed at gathering contributions from the most influential European groups working in the EAP field. In fact, today Europe hosts the broadest EAP community worldwide. The rapid expansion of the EAP field in Europe, where it historically has strong roots, has stimulated the creation of the 'European Scientific Network for Artificial

  12. Design of Autonomous Gel Actuators

    Directory of Open Access Journals (Sweden)

    Shuji Hashimoto

    2011-01-01

    Full Text Available In this paper, we introduce autonomous gel actuators driven by chemical energy. The polymer gels prepared here have cyclic chemical reaction networks. With a cyclic reaction, the polymer gels generate periodical motion. The periodic motion of the gel is produced by the chemical energy of the oscillatory Belouzov-Zhabotinsky (BZ reaction. We have succeeded in making synthetic polymer gel move autonomously like a living organism. This experimental fact represents the great possibility of the chemical robot.

  13. RESEARCH PROGRESS OF GEL POLYMER ELECTROLYTES FOR LITHIUM ION BATTERIES%锂离子电池凝胶聚合物电解质研究进展

    Institute of Scientific and Technical Information of China (English)

    张鹏; 李琳琳; 何丹农; 吴宇平; 清水真

    2011-01-01

    In recent decades,gel polymer electrolytes (GPEs) have received renewed attention in several areas such as lithium-ion batteries,solar cells and super capacitors due to their promising application. GPEs,swollen in a liquid electrolyte becoming plasticized or a gelled polymer electrolyte, have attracted particular attention because they may provide lighter and safer batteries with longer shelf life,leak proof construction andeasy fabrication into desired shape and size. However, GPEs still show poor mechanical strength due to the need for impregnation with the liquid electrolytes. This significant drawback of GPEs binders their practical application. To overcome these problems, in this review, the up-to-date technologies such as composite gel polymer electrolyte (CGPEs) and porous polymer electrolytes (PPEs) based on the gel concept have been summarized. In the CGPEs, the role of a filler in the membrane is to provide surface groups as physical crosslinking centers for the polymer segments, and thus reduce the polymer reorganization tendency which establishes additional conducting pathways on the filler surface. As a result, the nanosized particles not only lead to better ionic conductivity but also interact with the polymer hosts to enhance the mechanical strength. In PGPEs,due to the existence of the porous structure,the lithium ions can migrate not only in gel electrolyte butalso in liquid electrolyte stored in the pores, leading to higher ionic conductivity. In addition, the main characteristics of these gel polymer electrolytes were mentioned. Finally, the future directions are also pointed out.%使用聚合物电解质可以避免传统液态锂离子电池的漏液问题,提高电池的安全性能和能量密度,并可实现电池的薄型化、轻便化和形状可变等优点.目前,聚合物电解质的研究集中在凝胶型的复合和多孔聚合物电解质两大类.本文对各类凝胶聚合物电解质的特点、功能及研究情况逐一进

  14. Formulation and evaluation of antimicrobial activity of Morus alba sol-gel against periodontal pathogens

    Directory of Open Access Journals (Sweden)

    Shilpa Gunjal

    2015-01-01

    Full Text Available Background: Periodontitis has a multifactorial etiology, with primary etiologic agents being pathogenic bacteria that reside in the subgingival area. Recent advances in the field of alternative medicine introduced various herbal products for the treatment of periodontitis. Aim: To assess and compare the antimicrobial activity of Morus alba sol-gel with chlorhexidine sol-gel against ATCC standard strains of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Tannerella forsythia. Materials and Methods: Crude extract of Morus alba leaves was prepared by Soxhlet method by using ethanol as a solvent. Phytochemical screening of the crude extract of M. alba was performed to check the various chemical constituents. M. alba sol-gel and chlorhexidine sol-gel were formulated using Pluronic f127 and Pluronic f108 and compared for their antimicrobial activity. The minimum inhibitory concentration of both the gels was performed using agar well diffusion technique. Results: The minimum inhibitory concentration of M. alba sol-gel and chlorhexidine sol-gel against A. actinomycetemcomitans is 19 and 17 mm, T. forsythia is 12 and 21 mm, and P. gingivalis is 16 and 18 mm, respectively. Conclusion: Both M. alba and chlorhexidine sol-gel exhibited potent antimicrobial activity against periodontal pathogens.

  15. A technique for detecting antifungal activity of proteins separated by polyacrylamide gel electrophoresis.

    Science.gov (United States)

    De Bolle, M F; Goderis, I J; Terras, F R; Cammue, B P; Broekaert, W F

    1991-06-01

    A technique was developed for the detection of antifungal activity of proteins after discontinuous polyacrylamide gel electrophoresis under native conditions. The antifungal activity is detected as growth inhibition zones in a homogeneous fungal lawn, grown in an agar layer spread on top of the polyacrylamide gel. The position of proteins with antifungal activity can be determined on a diffusion blot prepared from the same gel. The technique is illustrated for three antifungal plant proteins, i.e. alpha-purothionin, Urtica dioica agglutinin, and tobacco chitinase.

  16. The history and principles of chemical dosimetry for 3-D radiation fields: gels, polymers and plastics.

    Science.gov (United States)

    Doran, Simon J

    2009-03-01

    Over recent decades, modern protocols of external beam radiotherapy have been developed that involve very steep dose gradients and are thus extremely sensitive to errors in treatment delivery. A recent credentialling study by the Radiological Physics Center at the MD Anderson Cancer Center (Texas, USA) has noted potentially significant inaccuracies in test treatments at a variety of institutions. 3-D radiation dosimetry (often referred to as "gel dosimetry") may have an important role in commissioning new treatment protocols, to help prevent this type of error. This article discusses the various techniques of 3-D radiation dosimetry, with a focus on the types of radiosensitive samples used and on the optical computed tomography readout technique.

  17. Dual phase polymer gel electrolyte based on non-woven poly(vinylidenefluoride-co-hexafluoropropylene)–layered clay nanocomposite fibrous membranes for lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Shubha, Nageswaran [School of Materials Science and Engineering, Nanyang Technological University, Block N4.1, 50 Nanyang Avenue, Singapore 639798 (Singapore); Prasanth, Raghavan [School of Materials Science and Engineering, Nanyang Technological University, Block N4.1, 50 Nanyang Avenue, Singapore 639798 (Singapore); Energy Research Institute - NTU (ERI-N) Research Techno Plaza, 50 Nanyang Drive, Singapore 637553 (Singapore); TUM-CREATE Center for Electromobility, Nanyang Technological University, Singapore 637553 (Singapore); Hoon, Hng Huey [School of Materials Science and Engineering, Nanyang Technological University, Block N4.1, 50 Nanyang Avenue, Singapore 639798 (Singapore); Srinivasan, Madhavi, E-mail: madhavi@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, Block N4.1, 50 Nanyang Avenue, Singapore 639798 (Singapore); Energy Research Institute - NTU (ERI-N) Research Techno Plaza, 50 Nanyang Drive, Singapore 637553 (Singapore); TUM-CREATE Center for Electromobility, Nanyang Technological University, Singapore 637553 (Singapore)

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► P(VdF-co-HFP)–clay nanocomposite based electrospun membranes are prepared. ► The membranes are used as polymer gel electrolyte (PGE) in lithium ion batteries. ► The composite PGE shows ionic conductivity of 5.5 mS cm{sup −1} at room temperature. ► Li/PGE/LiFePO{sub 4} cell delivers initial discharge capacity of 160 mAh g{sup −1}. ► The use of prepared electrolyte significantly improved the cell performance. -- Abstract: A new approach for fabricating polymer gel electrolytes (PGEs) based on electrospun poly(vinylidenefluoride-co-hexafluoropropylene) (P(VdF-co-HFP)) incorporated with layered nanoclay has been employed to enhance the ionic conductivity and electrochemical properties of P(VdF-co-HFP) without compromising its mechanical strength. The effect of layered nanoclay on properties of membranes has been evaluated by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Surface morphology of the membranes has been studied using field-emission scanning electron microscopy (FE-SEM). Polymer gel electrolytes are prepared by soaking the fibrous membrane into 1 M LiPF{sub 6} in EC/DEC. The electrochemical studies show that incorporation of layered nanoclay into the polymer matrix greatly enhanced the ionic conductivity and compatibility with lithium electrodes. The charge–discharge properties and cycling performance of Li/LiFePO{sub 4} cells comprising nanocomposite polymer gel electrolytes have been evaluated at room temperature.

  18. Shape memory polymers for active cell culture.

    Science.gov (United States)

    Davis, Kevin A; Luo, Xiaofan; Mather, Patrick T; Henderson, James H

    2011-07-04

    Shape memory polymers (SMPs) are a class of "smart" materials that have the ability to change from a fixed, temporary shape to a pre-determined permanent shape upon the application of a stimulus such as heat(1-5). In a typical shape memory cycle, the SMP is first deformed at an elevated temperature that is higher than its transition temperature, T(trans;) [either the melting temperature (T(m;)) or the glass transition temperature (T(g;))]. The deformation is elastic in nature and mainly leads to a reduction in conformational entropy of the constituent network chains (following the rubber elasticity theory). The deformed SMP is then cooled to a temperature below its T(trans;) while maintaining the external strain or stress constant. During cooling, the material transitions to a more rigid state (semi-crystalline or glassy), which kinetically traps or "freezes" the material in this low-entropy state leading to macroscopic shape fixing. Shape recovery is triggered by continuously heating the material through T(trans;) under a stress-free (unconstrained) condition. By allowing the network chains (with regained mobility) to relax to their thermodynamically favored, maximal-entropy state, the material changes from the temporary shape to the permanent shape. Cells are capable of surveying the mechanical properties of their surrounding environment(6). The mechanisms through which mechanical interactions between cells and their physical environment control cell behavior are areas of active research. Substrates of defined topography have emerged as powerful tools in the investigation of these mechanisms. Mesoscale, microscale, and nanoscale patterns of substrate topography have been shown to direct cell alignment, cell adhesion, and cell traction forces(7-14). These findings have underscored the potential for substrate topography to control and assay the mechanical interactions between cells and their physical environment during cell culture, but the substrates used to date

  19. A Polymer "Pollution Solution" Classroom Activity.

    Science.gov (United States)

    Helser, Terry L.

    1996-01-01

    Explains an approach to presenting polymer chemistry to nonmajors that employs polystyrene foam, foam peanuts made from water soluble starch, and water soluble plastic bags. Students are presented with a pollution scenario and are guided to the discovery of solutions. (DDR)

  20. In vivo evaluation of the delivery and efficacy of a sirolimus-laden polymer gel for inhibition of hyperplasia in a porcine model of arteriovenous hemodialysis graft stenosis.

    Science.gov (United States)

    Li, Li; Li, Huan; Zhuplatov, Ilya; Blumenthal, Donald K.; Kim, Seong-Eun; Owen, Shawn C.; Kholmovski, Eugene G.; Fowers, Kirk D.; Rathi, Ramesh; Cheung, Alfred K.

    2012-01-01

    Synthetic arteriovenous (AV) hemodialysis grafts are plagued by hyperplasia resulting in occlusion and graft failure yet there are no clinically available preventative treatments. Here the delivery and degradation of a sirolimus-laden polymer gel was monitored in vivo by magnetic resonance imaging (MRI) and its efficacy for inhibiting hyperplasia was evaluated in a porcine model of AV graft stenosis. Synthetic grafts were placed between the carotid artery and ipsilateral jugular vein of swine. A biodegradable polymer gel loaded with sirolimus (2.5 mg/mL) was immediately applied perivascularly to the venous anastomosis, and reapplied by ultrasound-guided injections at one, two and three weeks. Control grafts received neither sirolimus nor polymer. The lumen cross-sectional area at the graft-vein anastomosis was assessed in vivo by non-invasive MRI. The explanted tissues also underwent histological analysis. A specifically developed MRI pulse sequence provided a high contrast-to-noise ratio (CNR) between the polymer and surrounding tissue that allowed confirmation of gel location after injection. Polymer signal decreased up to 80% at three to four weeks after injection, slightly faster than its degradation kinetics in vitro. The MR image of the polymer was confirmed by visual assessment at necropsy. On histological assessment, the mean hyperplasia surface area of the treated graft was 52% lower than that of the control grafts (0.43 mm2 vs. 0.89 mm2; p hyperplasia development and an increase in lumen area at the venous anastomosis of AV grafts. PMID:22465391

  1. Plasminogen activator activity and plasma-coagulum lysis measured by use of optimized fibrin gel structure preformed in microtiter plates

    DEFF Research Database (Denmark)

    Sidelmann, Johannes Jakobsen; Jespersen, J; Gram, J

    1995-01-01

    gel, and the absorbance of the gel was recorded at 405 nm. After incubation for 17 h at 25 degrees C, the absorbance was measured again. The difference in absorbance was proportional to the concentration of plasminogen activator, such that the dose-response curves were linear when the difference...

  2. The transition from stress softening to stress hardening under cyclic loading induced by magnetic field for magneto-sensitive polymer gels

    Science.gov (United States)

    Xu, Yangguang; Liao, Guojiang; Zhang, Canyang; Wan, Qiang; Liu, Taixiang

    2016-04-01

    Magneto-sensitive polymer gel (MSPG) is a kind of ferromagnetic particle filled smart polymer composite, whose magneto-mechanical coupling mechanism has attracted increasing attention in recent years. In this work, the magneto-induced rheological response of MSPG under cyclic shear loading was investigated. It was found that magnetic field is the critical reason for the transition from stress softening to stress hardening under cyclic loading. Besides, the particle concentration and temperature are the controlling factors in the structure optimization of MSPG in the presence of magnetic field. The magneto-induced hardening mechanism was further proposed based on the related experimental results.

  3. Sampling tritiated water vapor from the atmosphere by an active system using silica gel

    Energy Technology Data Exchange (ETDEWEB)

    Herranz, M. [Department of Nuclear Engineering and Fluid Mechanics, E.T.S.I. de Bilbao, University of the Basque Country (UPV/EHU), Alameda de Urquijo, s/n 48013 Bilbao (Spain); Alegria, N., E-mail: natalia.alegria@ehu.es [Department of Nuclear Engineering and Fluid Mechanics, E.T.S.I. de Bilbao, University of the Basque Country (UPV/EHU), Alameda de Urquijo, s/n 48013 Bilbao (Spain); Idoeta, R.; Legarda, F. [Department of Nuclear Engineering and Fluid Mechanics, E.T.S.I. de Bilbao, University of the Basque Country (UPV/EHU), Alameda de Urquijo, s/n 48013 Bilbao (Spain)

    2011-11-15

    Among the different methods used to collect the tritiated water vapor (HTO) contained in the atmosphere, one of the most worldwide used is its collection using an air pump, which forces the air to pass through a dry silica gel trap. The silica gel is then distilled to remove the water collected, which is measured in a liquid scintillation counting system. In this paper, an analysis of the water collection efficiency of the silica gel has been done as a function of the temperatures involved, the dimensions of the pipe driving the air into the silica gel traps, the air volume passing through the trap and the flow rates used. Among the obtained conclusions, it can be pointed out that placing the traps inside a cooled container, the amount of silica gel needed to collect all the water contained in the air passing through these traps can be estimated using a weather forecast and a psychometric chart. To do this, and as thermal equilibrium between incoming and open air should be established, a suitable design of the sampling system is proposed. - Highlights: > To recollect the atmosphere air tritiated water vapor, an active system was used. > The system is an air pump and three traps with silica gel connected by a rubber pipe. > The silica gel retention depends on the meteorological conditions and the flow rate. > The amount of water collected and the mass of silica gel need were calculated, F.

  4. 3D polymer gel dosimetry and Geant4 Monte Carlo characterization of novel needle based X-ray source

    Science.gov (United States)

    Liu, Y.; Sozontov, E.; Safronov, V.; Gutman, G.; Strumban, E.; Jiang, Q.; Li, S.

    2010-11-01

    In the recent years, there have been a few attempts to develop a low energy x-ray radiation sources alternative to conventional radioisotopes used in brachytherapy. So far, all efforts have been centered around the intent to design an interstitial miniaturized x-ray tube. Though direct irradiation of tumors looks very promising, the known insertable miniature x-ray tubes have many limitations: (a) difficulties with focusing and steering the electron beam to the target; (b)necessity to cool the target to increase x-ray production efficiency; (c)impracticability to reduce the diameter of the miniaturized x-ray tube below 4mm (the requirement to decrease the diameter of the x-ray tube and the need to have a cooling system for the target have are mutually exclusive); (c) significant limitations in changing shape and energy of the emitted radiation. The specific aim of this study is to demonstrate the feasibility of a new concept for an insertable low-energy needle x-ray device based on simulation with Geant4 Monte Carlo code and to measure the dose rate distribution for low energy (17.5 keV) x-ray radiation with the 3D polymer gel dosimetry.

  5. Fabrication of ceramic oxide-coated SWNT composites by sol-gel process with a polymer glue

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Cheng; Gao Lei; Chen Yongming, E-mail: ymchen@iccas.ac.cn [Institute of Chemistry, Chinese Academy of Sciences, Laboratory of Polymer Physics and Chemistry (China)

    2011-09-15

    The functional copolymer bearing alkoxysilyl and pyrene groups, poly[3-(triethoxysilyl)propyl methacrylate]-co-[(1-pyrene-methyl) methacrylate] (TEPM{sub 13}-co-PyMMA{sub 3}), was synthesized via atom transfer radical polymerization. Attributing the {pi}-{pi} interaction of pyrene units with the walls of single-walled carbon nanotubes (SWNTs), this polymer could disperse and exfoliate SWNTs in different solvents through physical interaction as demonstrated by TEM, UV/Vis absorption, and FT-IR analysis. The alkoxysilyl groups functionalized SWNTs were reacted with different inorganic precursors via sol-gel reaction, and, as a results, silica, titania, and alumina were coated onto the surface of SWNTs, respectively via copolymers as a molecular glue. The nanocomposites of ceramic oxides/SWNTs were characterized by SEM analysis. Dependent upon the feed, the thickness of inorganic coating can be tuned easily. This study supplies a facile and general way to coat SWNTs with ceramic oxides without deteriorating the properties of pristine SWNTs.

  6. Novel polymer gel electrolyte with organic solvents for quasi-solid-state dye-sensitized solar cells.

    Science.gov (United States)

    Shen, Sheng-Yen; Dong, Rui-Xuan; Shih, Po-Ta; Ramamurthy, Vittal; Lin, Jiang-Jen; Ho, Kuo-Chuan

    2014-11-12

    A cross-linked copolymer was previously synthesized from poly(oxyethylene) diamine (POE-amine) and an aromatic anhydride and cured to generate an amide-imide cross-linking structure. The copolymer containing several chemical groups such as POE, amido acids, and imide, enabled to absorb liquid electrolytes in methoxypropionitrile (MPN) for suitable uses in dye-sensitized solar cells. To establish the advantages of polymer gel electrolytes (PGE), the same copolymer was studied by using different electrolyte solvents including propylene carbonate (PC), dimethylformamide, and N-methyl-2-pyrrolidone, and shown their long-term stability. The morphology of the copolymer after absorbing liquid electrolytes in these solvents was proven the same as a 3D interconnected nanochannels, evidenced field emission-scanning electron microscopy. Among these solvents, PC was selected as the optimized PGE, which demostrated a higher power conversion efficiency (8.31%) than that of the liquid electrolyte (7.89%). In particular, the long-term stability of only a 5% decrease in the cell efficiency after 1000 h of testing was achieved. It was proven the developed copolymer as PGE was versatile for different solvents showing high efficiency and long-term durability.

  7. Prevention of bovine mastitis by a postmilking teat disinfectant containing chlorous acid and chlorine dioxide in a soluble polymer gel.

    Science.gov (United States)

    Oliver, S P; King, S H; Torre, P M; Shull, E P; Dowlen, H H; Lewis, M J; Sordillo, L M

    1989-11-01

    A natural exposure study was conducted in a herd of 150 lactating dairy cows for 18 mo to determine the effectiveness of chlorous acid and chlorine dioxide in a soluble polymer gel as a postmilking teat disinfectant for the prevention of bovine mastitis. Right quarters of cows were dipped in the experimental teat dip after milking machine removal. Left quarters were not dipped and served as within-cow negative controls. The experimental teat dip reduced Staphylococcus aureus infections 67.4%, Streptococcus dysgalactiae infections 63.8%, and Streptococcus uberis infections 27.8%. Overall efficacy of the chlorous acid and chlorine dioxide teat dip against major mastitis pathogens was 52.2%. The experimental teat dip reduced Corynebacterium bovis infections and coagulase-negative staphylococcal infections also by 45.8 and 38.7%, respectively. Overall efficacy against minor mastitis pathogens was 43.4%. Under conditions of this trial, the experimental teat dip containing chlorous acid and chlorine dioxide was effective in preventing new intramammary infections against a variety of mastitis pathogens.

  8. Activation energy for mullitization of gel fibres obtained from aluminum isopropoxide

    Indian Academy of Sciences (India)

    Hongbin Tan; Yaping Ding; Haihong Zhang; Jianfeng Yang; Guanjun Qiao

    2012-10-01

    Gel fibres of mullite precursor were prepared from an aqueous solution of aluminum nitrate (AN), aluminum isopropoxide (AIP) and tetraethylorthosilicate (TEOS). A 4:1 molar ratio of aluminum isopropoxide and aluminum nitrate was optimized to obtain spinnable precursor sol for synthesis of fibres. Thermogravimetry–differential scanning calorimetry (TG–DSC), Fourier transform infrared (FTIR) spectra and X-ray diffraction (XRD) analyses were used to characterize properties of the gel and ceramic fibres. The precursor gel completely transformed to mullite at 1200 °C. The activation energy of mullite crystallization was 993.5 kJ/mol by the Kissinger equation.

  9. Probing the microenvironment of an oligo-(p-phenylene vinylene) derivative encapsulated in polymer-impregnated sol-gel silica matrix

    Institute of Scientific and Technical Information of China (English)

    TANG Jun; DU Chuang; YU Xiaoqiang; ZHANG Guo; WANG Ce

    2004-01-01

    Polymer-impregnated silica sol-gel composite materials are hosts for organics in advanced optics application. An oligo-phenylene vinylene derivative 4,4'-(1,4-phenylene dithenylene)-bis-(N-methyl pyridinium iodide)(OPVD) was introduced to poly(hydroxyethyl methacrylate)(PHEMA)-impregnated silica composite film by the sol-gel process. By comparing the X-ray diffraction, UV-visible spectra, steady-state and time-resolved fluorescence spectra of OPVD in three solid matrices (PHEMA/silica composite film, pure PHEMA film, and pure silica film), the similar results of PHEMA/silica composite film and pure PHEMA film demonstrate that the OPVD is primarily surrounded by a PHEMA-like environment in the composite matrix. The model of such structure is presented, which is useful for further understanding and optimizing of properties of doped sol-gel materials.

  10. Enhancement of thermal transport in Gel Polymer Electrolytes with embedded BN/Al2O3 nano- and micro-particles

    Science.gov (United States)

    Vishwakarma, Vivek; Jain, Ankur

    2017-09-01

    While Gel Polymer Electrolytes (GPEs) have been widely investigated for use in next-generation Li-ion cells due to the potential for improved thermal safety, thermal transport within a GPE is still poorly understood. Among all materials in a Li-ion cell, the GPE has the lowest thermal conductivity, and hence determines the overall rate of heat flow in a Li-ion cell. This makes it critical to measure and understand thermal transport in a GPE and investigate trade-offs between thermal and ionic transport. This paper presents measurements of thermal and ionic conductivities in a PVdF-based GPE. The effect of incorporating BN/Al2O3 ceramic nano/microparticles in the GPE on thermal and ionic transport is characterized. Measurements indicate up to 2.5X improvement in thermal conductivity of activated GPE membranes, with relatively minor effect on electrochemical performance of GPE-based single-layer cells. The measured enhancement in thermal conductivity is in very good agreement with theoretical calculations based on the effective medium theory that accounts for thermal transport in a dispersed, two-phase medium such as a GPE. The fundamental insights gained in this work on thermal transport in a GPE and the role of nano/microparticle inclusions may facilitate thermal-electrochemical optimization and design of GPEs for safe, high-performance Li-ion cells.

  11. Improved photovoltaic performance of inverted polymer solar cells through a sol-gel processed Al-doped ZnO electron extraction layer.

    Science.gov (United States)

    Kim, Jun Young; Cho, Eunae; Kim, Jaehoon; Shin, Hyeonwoo; Roh, Jeongkyun; Thambidurai, Mariyappan; Kang, Chan-mo; Song, Hyung-Jun; Kim, SeongMin; Kim, Hyeok; Lee, Changhee

    2015-09-21

    We demonstrate that nanocrystalline Al-doped zinc oxide (n-AZO) thin film used as an electron-extraction layer can significantly enhance the performance of inverted polymer solar cells based on the bulk heterojunction of poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl] (PCDTBT) and [6,6]-phenyl C(71)-butyric acid methyl ester (PC(70)BM). A synergistic study with both simulation and experiment on n-AZO was carried out to offer a rational guidance for the efficiency improvement. As a result, An n-AZO film with an average grain size of 13 to 22 nm was prepared by a sol-gel spin-coating method, and a minimum resistivity of 2.1 × 10(-3) Ω·cm was obtained for an Al-doping concentration of 5.83 at.%. When an n-AZO film with a 5.83 at.% Al concentration was inserted between the ITO electrode and the active layer (PCDTBT:PC(70)BM), the power conversion efficiency increased from 3.7 to 5.6%.

  12. Toward highly stable solid-state unconventional thin-film battery-supercapacitor hybrid devices: Interfacing vertical core-shell array electrodes with a gel polymer electrolyte

    Science.gov (United States)

    Pandey, Gaind P.; Klankowski, Steven A.; Liu, Tao; Wu, Judy; Li, Jun

    2017-02-01

    A novel solid-state battery-supercapacitor hybrid device is fabricated for high-performance electrical energy storage using a Si anode and a TiO2 cathode in conjunction with a flexible, solid-like gel polymer electrolyte film as the electrolyte and separator. The electrodes were fabricated as three-dimensional nanostructured vertical arrays by sputtering active materials as conformal shells on vertically aligned carbon nanofibers (VACNFs) which serve as the current collector and structural template. Such nanostructured vertical core-shell array-electrodes enable short Li-ion diffusion path and large pseudocapacitive contribution by fast surface reactions, leading to the hybrid features of batteries and supercapacitors that can provide high specific energy over a wide range of power rates. Due to the improved mechanical stability of the infiltrated composite structure, the hybrid cell shows excellent cycling stability and is able to retain more than 95% of the original capacity after 3500 cycles. More importantly, this solid-state device can stably operate in a temperature range from -20 to 60 °C with a very low self-discharge rate and an excellent shelf life. This solid-state architecture is promising for the development of highly stable thin-film hybrid energy storage devices for unconventional applications requiring largely varied power, wider operation temperature, long shelf-life and higher safety standards.

  13. The potential of incorporation of binary salts and ionic liquid in P(VP-co-VAc) gel polymer electrolyte in electrochemical and photovoltaic performances

    Science.gov (United States)

    Ming, Ng Hon; Ramesh, S.; Ramesh, K.

    2016-06-01

    In this study, dye-sensitized solar cells (DSSCs) has been assembled with poly(1-vinylpyrrolidone-co-vinyl acetate) (P(VP-co-VAc)) gel polymer electrolytes (GPEs) which have been incorporated with binary salt and an ionic liquid. The potential of this combination was studied and reported. The binary salt system GPEs was having ionic conductivity and power conversion efficiency (PCE) that could reach up to 1.90 × 10‑3 S cm‑1 and 5.53%, respectively. Interestingly, upon the addition of the ionic liquid, MPII into the binary salt system the ionic conductivity and PCE had risen steadily up to 4.09 × 10‑3 S cm‑1 and 5.94%, respectively. In order to know more about this phenomenon, the electrochemical impedance studies (EIS) of the GPE samples have been done and reported. Fourier transform infrared studies (FTIR) and thermogravimetric analysis (TGA) have also been studied to understand more on the structural and thermal properties of the GPEs. The Nyquist plot and Bodes plot studies have been done in order to understand the electrochemical properties of the GPE based DSSCs and Tafel polarization studies were done to determine the electrocatalytic activity of the GPE samples.

  14. Ion activated in situ gel system for ophthalmic delivery of moxifloxacin hydrochloride

    OpenAIRE

    Mali, Mahesh N.; Ashok A. Hajare

    2010-01-01

    Rapid precorneal elimination of drug is a major limitation of conventional ophthalmic formulations. An ion activated in situ gel forming systems of an antibacterial agent moxifloxacin hydrochloride for instillation as drops into eye undergoing a sol to gel transition in the cul-de-sac was formulated. Sodium alginate was used as the gelling agent in combination with hydroxypropylmethyl cellulose. Formulations were evaluated for gelling capacity, pH, in vitro release, rheological study, Draize ...

  15. Shape Memory Polymers for Active Cell Culture

    OpenAIRE

    Davis, Kevin A.; Luo, Xiaofan; Mather, Patrick T.; Henderson, James H.

    2011-01-01

    Shape memory polymers (SMPs) are a class of "smart" materials that have the ability to change from a fixed, temporary shape to a pre-determined permanent shape upon the application of a stimulus such as heat1-5. In a typical shape memory cycle, the SMP is first deformed at an elevated temperature that is higher than its transition temperature, Ttrans [either the melting temperature (Tm) or the glass transition temperature (Tg)]. The deformation is elastic in nature and mainly leads to a reduc...

  16. A Gel-Polymer Sn-C/LiMn0.5Fe0.5PO4 Battery Using a Fluorine-Free Salt.

    Science.gov (United States)

    Di Lecce, Daniele; Fasciani, Chiara; Scrosati, Bruno; Hassoun, Jusef

    2015-09-30

    Safety and environmental issues, because of the contemporary use of common liquid electrolytes, fluorinated salts, and LiCoO2-based cathodes in commercial Li-ion batteries, might be efficiently mitigated by employing alternative gel-polymer battery configurations and new electrode materials. Herein we study a lithium-ion polymer cell formed by combining a LiMn0.5Fe0.5PO4 olivine cathode, prepared by simple solvothermal pathway, a nanostructured Sn-C anode, and a LiBOB-containing PVdF-based gel electrolyte. The polymer electrolyte, here analyzed in terms of electrochemical stability by impedance spectroscopy (EIS) and voltammetry, reveals full compatibility for cell application. The LiBOB electrolyte salt and the electrochemically delithiaded Mn0.5Fe0.5PO4 have a higher thermal stability compared to conventional LiPF6 and Li0.5CoO2, as confirmed by thermogravimetric analysis (TGA) and by galvanostatic cycling at high temperature. LiMn0.5Fe0.5PO4 and Sn-C, showing in lithium half-cell a capacity of about 120 and 350 mAh g(-1), respectively, within the gelled electrolyte configuration are combined in a full Li-ion polymer battery delivering a stable capacity of about 110 mAh g(-1), with working voltage ranging from 2.8 to 3.6 V.

  17. Hydrolytic Activity of Esterase-Antibody Complexes Retained Within Gel Capsules After Complex Isolation.

    Science.gov (United States)

    Shimazaki, Youji; Miyatsuka, Rino

    2017-01-09

    Delipidation in biological samples is important for some diagnostic tests and protein analyses. Lipids in the samples can be hydrolyzed by native esterases (ESs) within gel capsules after ES, and ES-antibody complexes are specifically trapped, extracted, and separated. Acrylamide and agarose gel capsules containing complexes of ES antibody were produced after the complexes were extracted using protein A-immobilized membranes, separated by non-denaturing electrophoresis, and stained by colloidal silver using glucose as a reductant. ES activity of ES-antibody complexes within the gel capsule was significantly higher than that in the complexes with the control antibodies upon isolation, separation, and detection of the complex. In addition, lipids bound to human serum albumin decreased after human plasma was treated with gel capsules containing ES-antibody complexes. We demonstrate that the gel capsule containing ES-antibody complexes can be successfully isolated using techniques described in this study. Furthermore, delipidation of human plasma is obtained by incubation with the gel capsule. These results indicate that surplus materials such as lipids in biological samples can be removed or reduced by gel capsule containing enzymes.

  18. In situ ceramic fillers of electrospun thermoplastic polyurethane/poly(vinylidene fluoride) based gel polymer electrolytes for Li-ion batteries

    Science.gov (United States)

    Wu, Na; Cao, Qi; Wang, Xianyou; Li, Sheng; Li, Xiaoyun; Deng, Huayang

    Gel polymer electrolyte films based on thermoplastic polyurethane (TPU)/poly(vinylidene fluoride) (PVdF) with and without in situ ceramic fillers (SiO 2 and TiO 2) are prepared by electrospinning 9 wt% polymer solution at room temperature. The electrospun TPU-PVdF blending membrane with 3% in situ TiO 2 shows a highest ionic conductivity of 4.8 × 10 -3 S cm -1 with electrochemical stability up to 5.4 V versus Li +/Li at room temperature and has a high tensile strength (8.7 ± 0.3 MPa) and % elongation at break (110.3 ± 0.2). With the superior electrochemical and mechanical performance, it is very suitable for application in polymer lithium ion batteries.

  19. Assessment of Anti HSV-1 Activity of Aloe Vera Gel Extract: an In Vitro Study

    Science.gov (United States)

    Rezazadeh, Fahimeh; Moshaverinia, Maryam; Motamedifar, Mohammad; Alyaseri, Montazer

    2016-01-01

    Statement of the Problem Herpes simplex virus (HSV) infection is one of the most common and debilitating oral diseases; yet, there is no standard topical treatment to control it. The extract of Aloe vera leaves has been previously reported to have anti-inflammatory, antibacterial, and also antiviral effects. There is no data on anti-Herpes simplex virus type 1 (HSV-1) activity of Aloe vera gel. Purpose This study aimed to evaluate the anti-HSV-1 activity of Aloe vera gel in Vero cell line. Materials and Method In this study, gel extraction and cytotoxicity of various increasing concentrations of Aloe vera gel (0.2, 0.5, 1, 2, and 5%) was evaluated in Dulbecco’s Modified Eagle Medium (DMEM) containing 2% fetal bovine serum (FBS). Having been washed with phosphate buffered saline, 50 plaque-forming units (PFU) of HSV-1 was added to each well. After 1 hour of incubation at 37°C, cell monolayers in 24 well plates were exposed to different increasing concentrations of Aloe vera gel. The anti-HSV-1 activity of Aloe vera gel in different concentrations was assessed by plaque reduction assays. Data were analyzed by using One-way ANOVA. Results The cytotoxicity assay showed that Aloe vera in prearranged concentrations was cell-compatible. The inhibitory effect of various concentrations of Aloe vera was observed one hour after the Vero cell was infected with HSV-1. However, there was no significant difference between two serial concentrations (p> 0.05). One-way ANOVA also revealed no significant difference between the groups. The findings indicated a dose-dependent antiviral effect of Aloe vera. Conclusion The findings showed significant inhibitory effect of 0.2-5% Aloe vera gel on HSV-1 growth in Vero cell line. Therefore, this gel could be a useful topical treatment for oral HSV-1 infections without any significant toxicity. PMID:26966709

  20. Assessment of Anti HSV-1 Activity of Aloe Vera Gel Extract: an In Vitro Study.

    Science.gov (United States)

    Rezazadeh, Fahimeh; Moshaverinia, Maryam; Motamedifar, Mohammad; Alyaseri, Montazer

    2016-03-01

    Herpes simplex virus (HSV) infection is one of the most common and debilitating oral diseases; yet, there is no standard topical treatment to control it. The extract of Aloe vera leaves has been previously reported to have anti-inflammatory, antibacterial, and also antiviral effects. There is no data on anti-Herpes simplex virus type 1 (HSV-1) activity of Aloe vera gel. This study aimed to evaluate the anti-HSV-1 activity of Aloe vera gel in Vero cell line. In this study, gel extraction and cytotoxicity of various increasing concentrations of Aloe vera gel (0.2, 0.5, 1, 2, and 5%) was evaluated in Dulbecco's Modified Eagle Medium (DMEM) containing 2% fetal bovine serum (FBS). Having been washed with phosphate buffered saline, 50 plaque-forming units (PFU) of HSV-1 was added to each well. After 1 hour of incubation at 37°C, cell monolayers in 24 well plates were exposed to different increasing concentrations of Aloe vera gel. The anti-HSV-1 activity of Aloe vera gel in different concentrations was assessed by plaque reduction assays. Data were analyzed by using One-way ANOVA. The cytotoxicity assay showed that Aloe vera in prearranged concentrations was cell-compatible. The inhibitory effect of various concentrations of Aloe vera was observed one hour after the Vero cell was infected with HSV-1. However, there was no significant difference between two serial concentrations (p> 0.05). One-way ANOVA also revealed no significant difference between the groups. The findings indicated a dose-dependent antiviral effect of Aloe vera. The findings showed significant inhibitory effect of 0.2-5% Aloe vera gel on HSV-1 growth in Vero cell line. Therefore, this gel could be a useful topical treatment for oral HSV-1 infections without any significant toxicity.

  1. Fabrication of TiO{sub 2} {mu}-donuts by sol-gel spin coating using a polymer mask

    Energy Technology Data Exchange (ETDEWEB)

    Saleema, N. [Atmospheric Icing Engineering of Power Networks (CIGELE) and Atmospheric Icing of Power Network Equipment (INGIVRE), Universite du Quebec a Chicoutimi, 555 Blvd. University, Quebec, G7H 2B1 (Canada)], E-mail: snoormoh@uqac.ca; Farzaneh, M. [Atmospheric Icing Engineering of Power Networks (CIGELE) and Atmospheric Icing of Power Network Equipment (INGIVRE), Universite du Quebec a Chicoutimi, 555 Blvd. University, Quebec, G7H 2B1 (Canada); Paynter, R.W. [INRS, Centre Energie Materiaux Telecommunications, 1650 Boulevard Lionel-Boulet, Varennes, Quebec, J3X 1S2 (Canada)

    2009-03-15

    TiO{sub 2} {mu}-donuts have been fabricated on glass and silicon substrates using polymer masks in combination with a sol-gel technique. Cylindrical poly(methyl methacrylate) (PMMA) nanopillars have been created using a composite polymer of polystyrene (PS) and PMMA followed by careful removal of the PS. Atomic force microscopy (AFM) analyses show that the height and diameter of the PMMA cylinders used as the mask are 440 {+-} 5 nm and 2.1 {+-} 0.2 {mu}m, respectively. The cylindrical PMMA nanopillars have been coated with the sol of the TiO{sub 2} precursor by a spin coating technique and annealed in air at elevated temperature to remove the PMMA mask. Removal of the PMMA mask has resulted in the formation of well ordered {mu}-donuts of TiO{sub 2} on silicon surfaces. The interior and exterior heights of the TiO{sub 2} {mu}-donuts are found to be 373 {+-} 152 nm and 457 {+-} 136 nm, respectively; and the interior and exterior diameters of the TiO{sub 2} {mu}-donuts are found to be 1.33 {+-} 0.63 {mu}m and 2.82 {+-} 0.50 {mu}m, respectively. X-ray photoelectron spectroscopy (XPS) spectra of the TiO{sub 2} {mu}-donuts as well as the smooth TiO{sub 2} thin film showed signals from Ti and O confirming the presence of TiO{sub 2} with Ti 2p{sub 3/2} and O 1s peaks at 458.8 eV and 530.4 eV, respectively. The O 1s peak of the TiO{sub 2} {mu}-donuts shows another peak at binding energy 532.0 eV due to SiO{sub 2}, as during annealing, the PMMA evaporates and the Si substrate is exposed. The X-ray diffractometer (XRD) pattern of the smooth TiO{sub 2} thin film indicates that the anatase phase is present, with the characteristic peaks observed at 2{theta} values of 25.4{sup o}, 37.4{sup o}, and 48{sup o} corresponding to (1 0 1), (0 0 4), and (2 0 0) planes, respectively. UV-vis absorption spectra of TiO{sub 2} {mu}-donuts on glass showed an unusual absorption of light in the visible region at {approx}524 nm in addition to the usual UV absorption at {approx}337 nm.

  2. Active fluidization of polymer networks through molecular motors.

    Science.gov (United States)

    Humphrey, D; Duggan, C; Saha, D; Smith, D; Käs, J

    2002-03-28

    Entangled polymer solutions and melts exhibit elastic, solid-like resistance to quick deformations and a viscous, fluid-like response to slow deformations. This viscoelastic behaviour reflects the dynamics of individual polymer chains driven by brownian motion: since individual chains can only move in a snake-like fashion through the mesh of surrounding polymer molecules, their diffusive transport, described by reptation, is so slow that the relaxation of suddenly imposed stress is delayed. Entangled polymer solutions and melts therefore elastically resist deforming motions that occur faster than the stress relaxation time. Here we show that the protein myosin II permits active control over the viscoelastic behaviour of actin filament solutions. We find that when each actin filament in a polymerized actin solution interacts with at least one myosin minifilament, the stress relaxation time of the polymer solution is significantly shortened. We attribute this effect to myosin's action as a 'molecular motor', which allows it to interact with randomly oriented actin filaments and push them through the solution, thus enhancing longitudinal filament motion. By superseding reptation with sliding motion, the molecular motors thus overcome a fundamental principle of complex fluids: that only depolymerization makes an entangled, isotropic polymer solution fluid for quick deformations.

  3. Inhibitory activity of Aloe vera gel on some clinically isolated cariogenic and periodontopathic bacteria.

    Science.gov (United States)

    Fani, Mohammadmehdi; Kohanteb, Jamshid

    2012-03-01

    Aloe vera is a medicinal plant with anti-inflammatory, antimicrobial, antidiabetic and immune-boosting properties. In the present study we investigated the inhibitory activities of Aloe vera gel on some cariogenic (Streptococcus mutans), periodontopathic (Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis) and an opportunistic periodontopathogen (Bacteroides fragilis) isolated from patients with dental caries and periodontal diseases. Twenty isolates of each of these bacteria were investigated for their sensitivity to Aloe vera gel using the disk diffusion and microdilution methods. S. mutans was the species most sensitive to Aloe vera gel with a MIC of 12.5 µg/ml, while A. actinomycetemcomitans, P. gingivalis, and B. fragilis were less sensitive, with a MIC of 25-50 µg/ml (P Aloe vera gel at optimum concentration could be used as an antiseptic for prevention of dental caries and periodontal diseases.

  4. Spectrum of antimicrobial activity and user acceptability of the hand disinfectant agent Sterillium Gel.

    Science.gov (United States)

    Kampf, G; Rudolf, M; Labadie, J-C; Barrett, S P

    2002-10-01

    The antimicrobial efficacy of alcohol-based hand gels has been shown to be significantly less than liquid hand rubs probably because of a lower concentration of alcohol. Sterillium Gel is the first hand gel with 85% ethanol. Its antimicrobial efficacy and user acceptability was studied. Bactericidal activity was tested according to prEN 12054 against Staphylococcus aureus, Enterococcus hirae, Pseudomonas aeruginosa and Escherichia coli (suspension test) and EN 1500 (15 volunteers; four replicates), fungicidal activity according to EN 1275 against Candida albicans and spores of Aspergillus niger (suspension test) and tuberculocidal activity against Mycobacterium terrae using the DGHM suspension test. Virucidal activity was determined in suspension tests based on reduction of infectivity with and without interfering substances (10% fetal calf serum; 0.3% erythrocytes and 0.3% bovine serum albumin). Ninety-six healthcare workers in hospitals in France and the UK used the gel for four weeks and assessed it by filling out a questionnaire. The gel was bactericidal (a reduction factor of > 10(5)-fold), tuberculocidal (reduction factor > 10(5)) and fungicidal (reduction factor > 10(4)) in 30 s. Irrespective of interfering substances the gel inactivated orthopoxvirus and herpes simplex virus type 1 and 2 in 15 s, adenovirus in 2 min, poliovirus in 3 min and papovavirus in 15 min by a factor of > 10(4)-fold. Rotavirus and human immunodeficiency virus were inactivated in 30 s (without interfering substances). Under practical use conditions it was as effective in 30 s as the reference alcohol in 60 s. Most users described the tackiness, aggregation, skin feeling after use and smell as positive or acceptable. A total of 65.6% assessed the new gel to be better than a comparator irrespective of its type (gel or liquid). Overall Sterillium Gel had a unique spectrum of antimicrobial activity. It is probably the first alcohol-based hand gel to pass EN 1500 in 30 s. Due to the

  5. Extended release microparticle-in-gel formulation of octreotide: Effect of polymer type on acylation of peptide during in vitro release.

    Science.gov (United States)

    Vaishya, Ravi D; Mandal, Abhirup; Patel, Sulabh; Mitra, Ashim K

    2015-12-30

    Polymeric microparticles (MPs)-in-gel formulations for extended delivery of octreotide were developed. We investigated influence of polymer composition on acylation of octreotide and kinetics of release during in vitro release from biodegradable polymeric formulations. Polycaprolactone (PCL), polylactic acid (PLA), polyglycolic acid (PGA) and polyethylene glycol (PEG) based triblock (TB≈PCL10k-PEG2k-PCL10k) and pentablock (PBA≈PLA3k-PCL7k-PEG2k-PCL7k-PLA3k and PBB≈PGA3k-PCL7k-PEG2k-PCL7k-PGA3k) polymers were investigated. Octreotide was encapsulated in MPs using methanol-oil/water emulsion solvent evaporation method. The particles were characterized for size, morphology, encapsulation efficiency, drug loading and in vitro release. Release samples were subjected to HPLC analysis for quantitation and HPLC-MS analysis for identification of native and chemically modified octreotide adducts. Entrapment efficiency of methanol-oil/water method with TB, PBA and PBB polymers were 45%, 60%, and 82%, respectively. A significant fraction of released octreotide was acylated from lactide and glycolide based PBA (53%) and PBB (92%) polymers. Substantial amount of peptide was not released from PBB polymers after 330 days of incubation. Complete release of octreotide was achieved from TB polymer over a period of 3 months with minimal acylation of peptide (13%). PCL based polymers resulted in minimal acylation of peptide and hence may be suitable for extended peptide and protein delivery. Conversely, polymers having PLA and PGA blocks may not be appropriate for peptide delivery due to acylation and incomplete release.

  6. Study on properties of gel polymer electrolytes of PVDF-HFP%凝胶聚合物PVDF-HFP电解质膜的性能研究

    Institute of Scientific and Technical Information of China (English)

    芮含笑; 乔庆东; 李琪

    2012-01-01

    The lithium ion batteries are commercialized due to their shape versatility, flexibility, and lightness and can meet the demands of microelectronic industries. Poly (vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) is one of the most popular polymers for gel polymer electrolytes (GPE) because of its high ionic conductivity, good mechanical, thermal, interfacial, and electrochemical stabilities. In this paper, the progress and the composition of solid polymer electrolyte based on PVDF-HFP was reviewed briefly and the preparation technology of the polymer electrolyte was introduced. The influences on the properties of the polymer electrolyte were analyzed. The progress of modified the polymer electrolyte were discussed, including the modification of filler, plasticizer, polymer, . Copolymerization and blending technologies. The development of polymer electrolyte in the future was also suggested.%锂离子电池由于形状多样化、灵活性及轻便等优点而用于商业化生产,满足微型电子工业的需要,而偏氟乙烯和六氟丙烯的共聚物PVDF-HFP由于较高的电导率,较好的机械强度和热稳定性,优良的界面特性和电化学性能而被认为是最受欢迎的一种聚合物电解质.主要综述了PVDF-HFP固体电解质的组成、制备方法和进展,讨论了PVDF-HFP电解质的改性措施:填料改性、增塑剂改性、共聚共混改性及聚合物改性.对今后的发展方向作了简单展望.

  7. Release-Modulated Antioxidant Activity of a Composite Curcumin-Chitosan Polymer.

    Science.gov (United States)

    O'Toole, Martin G; Soucy, Patricia A; Chauhan, Rajat; Raju, Mandapati V Ramakrishnam; Patel, Dhruvina N; Nunn, Betty M; Keynton, Megan A; Ehringer, William D; Nantz, Michael H; Keynton, Robert S; Gobin, Andrea S

    2016-04-11

    Curcumin is known to have immense therapeutic potential but is hindered by poor solubility and rapid degradation in solution. To overcome these shortcomings, curcumin has been conjugated to chitosan through a pendant glutaric anhydride linker using amide bond coupling chemistry. The hybrid polymer has been characterized by UV-visible, fluorescence, and infrared spectroscopies as well as zeta potential measurements and SEM imaging. The conjugation reactivity was confirmed through gel permeation chromatography and quantification of unconjugated curcumin. An analogous reaction of curcumin with glucosamine, a small molecule analogue for chitosan, was performed and the purified product characterized by mass spectrometry, UV-visible, fluorescence, and infrared spectroscopies. Conjugation of curcumin to chitosan has greatly improved curcumin aqueous solubility and stability, with no significant curcumin degradation detected after one month in solution. The absorbance and fluorescence properties of curcumin are minimally perturbed (λmax shifts of 2 and 5 nm, respectively) by the conjugation reaction. This conjugation strategy required use of one out of two curcumin phenols (one of the main antioxidant functional groups) for covalent linkage to chitosan, thus temporarily attenuating its antioxidant capacity. Hydrolysis-based release of curcumin from the polymer, however, is accompanied by full restoration of curcumin's antioxidant potential. Antioxidant assays show that curcumin radical scavenging potential is reduced by 40% after conjugation, but that full antioxidant potential is restored upon hydrolytic release from chitosan. Release studies show that curcumin is released over 19 days from the polymer and maintains a concentration of 0.23 ± 0.12 μM curcumin/mg polymer/mL solution based on 1% curcumin loading on the polymer. Release studies in the presence of carbonic anhydrase, an enzyme with known phenolic esterase activity, show no significant difference from

  8. Transport Phenomena in Gel

    Directory of Open Access Journals (Sweden)

    Masayuki Tokita

    2016-05-01

    Full Text Available Gel becomes an important class of soft materials since it can be seen in a wide variety of the chemical and the biological systems. The unique properties of gel arise from the structure, namely, the three-dimensional polymer network that is swollen by a huge amount of solvent. Despite the small volume fraction of the polymer network, which is usually only a few percent or less, gel shows the typical properties that belong to solids such as the elasticity. Gel is, therefore, regarded as a dilute solid because its elasticity is much smaller than that of typical solids. Because of the diluted structure, small molecules can pass along the open space of the polymer network. In addition to the viscous resistance of gel fluid, however, the substance experiences resistance due to the polymer network of gel during the transport process. It is, therefore, of importance to study the diffusion of the small molecules in gel as well as the flow of gel fluid itself through the polymer network of gel. It may be natural to assume that the effects of the resistance due to the polymer network of gel depends strongly on the network structure. Therefore, detailed study on the transport processes in and through gel may open a new insight into the relationship between the structure and the transport properties of gel. The two typical transport processes in and through gel, that is, the diffusion of small molecules due to the thermal fluctuations and the flow of gel fluid that is caused by the mechanical pressure gradient will be reviewed.

  9. Antiinflammatory activity of tenoxicam gel on carrageenan-induced paw oedema in rats

    Directory of Open Access Journals (Sweden)

    Gupta G

    2006-01-01

    Full Text Available Tenoxicam is a nonsteroidal antiinflammatory drug, used in the treatment of inflammatory and degenerative disorders of the musculoskeletal system. It is from the oxicam group of nonsteroidal antiinflammatory agents. It is widely prescribed for the treatment of osteoarthritis, rheumatoid arthritis, ankylosing spondylitis, gout, extra-articular disorders, bursitis, tendonitis, and nonarticular rheumatic condition. Tenoxicam has some side effects when taken orally, viz., epigastric pain, heartburn, nausea, diarrhoea, vomiting, peptic ulcer, and hepatic impairment. The aim of this study was to formulate topical gel containing 1% of tenoxicam in 1% carbopol-940 and PEG-4000 and to evaluate it for antiinflammatory activity using carrageenan-induced paw oedema in rats. The studies were conducted on Wistar rats of either sex (160-180 g. The change in oedema volume of the rat hind paw was measured using mercury plethysmometer. The readings were measured in terms of volume displaced in millimetre using a micropipette that has mark to 10 divisions in 1 ml. The carbopol gel formulation of tenoxicam containing 15% of ethanol and 5% of sodium lauryl sulphate was significantly more effective against oedema formation than the other formulation of tenoxicam gel and compared to the marketed product of piroxicam gel. Results suggest that the 1% tenoxicam gel in carbopol-940 inhibited 52% of carrageenan-induced oedema formation as compared with the 44% inhibition obtained with marketed product of piroxicam gel.

  10. Structure and properties of Li-ion conducting polymer gel electrolytes based on ionic liquids of the pyrrolidinium cation and the bis(trifluoromethanesulfonyl)imide anion

    Science.gov (United States)

    Pitawala, Jagath; Navarra, Maria Assunta; Scrosati, Bruno; Jacobsson, Per; Matic, Aleksandar

    2014-01-01

    We have investigated the structure and physical properties of Li-ion conducting polymer gel electrolytes functionalized with ionic liquid/lithium salt mixtures. The membranes are based on poly(vinylidene fluoride-co-hexafluoropropylene) copolymer, PVdF-HFP, and two ionic liquids: pyrrolidinium cations, N-butyl-N-methylpyrrolidinium (PyR14+), N-butyl-N-ethylpyrrolidinium (PyR24+), and bis(trifluoromethanesulfonyl)imide anion (TFSI). The ionic liquids where doped with 0.2 mol kg--1 LiTFSI. The resulting membranes are freestanding, flexible, and nonvolatile. The structure of the polymer and the interactions between the polymer and the ionic liquid electrolyte have been studied using Raman spectroscopy. The ionic conductivity of the membranes has been studied using dielectric spectroscopy whereas the thermal properties were investigated using differential scanning caloriometry (DSC). These results show that there is a weak, but noticeable, influence on the physical properties of the ionic liquid by the confinement in the membrane. We observe a change in the Li-ion coordination, conformation of the anion, the fragility and a slight increase of the glass transition temperatures for IL/LiTFSI mixtures in the membranes compared to the neat mixtures. The effect can be related to the confinement of the liquid in the membrane and/or to interactions with the PVdF-HFP polymer matrix where the crystallinity is decreased compared to the starting polymer powder.

  11. Molecularly imprinted polymers on the surface of silica microspheres via sol-gel method for the selective extraction of streptomycin in aqueous samples.

    Science.gov (United States)

    Junjie, Li; Mei, Yang; Danqun, Huo; Changjun, Hou; Xianliang, Li; Guomin, Wang; Dan, Feng

    2013-03-01

    Streptomycin-imprinted silica microspheres were prepared by combining a surface molecular-imprinting technique with the sol-gel method. A mixture of tetrahydrofuran, ethanol, and water (6:1:1, v/v/v) was selected as dispersing solvent while 3-aminopropyltriethoxysilane and triethoxyphenylsilane acted as functional monomers, and tetraethyl orthosilicate as a cross-linker. Characterization of the molecularly imprinted polymers was conducted using scanning electron microscope and dynamic binding experiments. As compared to the nonimprinted polymers, the imprinted polymers exhibited a higher degree of saturated adsorption volume up to 26.3 mg/g, and better selectivity even in an aqueous solution with interfering compounds, including dihydrostreptomycin, neomycin, and tetracycline. The adsorption ability and selectivity were observed to be influenced by the mole ratio of 3-aminopropyltriethoxysilane and triethoxyphenylsilane. Feasibility of the polymers to be used for actual application was also evaluated with spiked samples, indicating great potential for large-scale applications. Moreover, the streptomycin-imprinted polymers can be repeatedly used for 12 cycles without losing original performance, which is beneficial for commercial use.

  12. Water-compatible silica sol-gel molecularly imprinted polymer as a potential delivery system for the controlled release of salicylic acid.

    Science.gov (United States)

    Li, Bin; Xu, Jingjing; Hall, Andrew J; Haupt, Karsten; Tse Sum Bui, Bernadette

    2014-09-01

    Molecularly imprinted polymers (MIPs) for salicylic acid were synthesized and evaluated in aqueous environments in the aim to apply them as drug delivery carriers. One organic MIP and one inorganic MIP based on the sol-gel process were synthesized. The organic MIP was prepared by radical polymerization using the stoichiometric functional monomer, 1-(4-vinylphenyl)-3-(3,5-bis(trifluoromethyl)phenyl)urea, which can establish strong electrostatic interactions with the -COOH of salicylic acid. The sol-gel MIP was prepared with 3-(aminopropyl)triethoxysilane and trimethoxyphenylsilane, as functional monomers and tetraethyl orthosilicate as the crosslinker. While the organic MIPs bound the target specifically in acetonitrile, they exhibited lower binding in the presence of water, although the imprinting factor increased under these conditions, due to reduced non-specific binding. The sol-gel MIP has a high specificity and capacity for the drug in ethanol, a solvent compatible with drug formulation and biomedical applications. In vitro release profiles of the polymers in water were evaluated, and the results were modelled by Fick's law of diffusion and the power law. Analysis shows that the release mechanism was predominantly diffusion-controlled.

  13. Research progress of modifying P(VDF-HFP)based gel polymer electrolyte%改性P(VDF-HFP)基凝胶聚合物电解质研究进展

    Institute of Scientific and Technical Information of China (English)

    梁子雷; 李琪; 孙悦; 乔庆东

    2009-01-01

    Gel polymer electrolyte is one of the priority materials for advanced lithium ion battery research. It plays an important role in lithium ion battery's development. The research progress in recent years in modifying P(VDF-HFP) based gel polymer electrolytes for polymer Li-ion battery was reviewed. The preparation and ionic conductivity of hybrid gel polymer electrolyte (HGPE) and nanocomposites gel polymer electrolyte (NGPE) was comprehensively introduced. The application prospect of P (VDF-HFP) based gel polymer electrolyte for Li-ion battery was put forward.%凝胶聚合物电解质是先进锂离子电池材料研究的重点之一,对其未来的发展起到至关重要的作用.总结了国内外近年来聚合物锂离子电池改性P(VDF-HFP);凝胶聚合物电解质的研究成果;重点介绍了共混凝胶聚合物电解质和纳米复合凝胶聚合物电解质的制备方法及其离子导电性;并对P(VDF-HFP)基凝胶聚合物电解质在锂离子电池中的应用做出了展望.

  14. A new redox-active coordination polymer with cobalticinium dicarboxylate.

    Science.gov (United States)

    Kondo, Mitsuru; Hayakawa, Yuri; Miyazawa, Makoto; Oyama, Aiko; Unoura, Kei; Kawaguchi, Hiroyuki; Naito, Tetsuyoshi; Maeda, Kenji; Uchida, Fumio

    2004-09-20

    A new two-dimensional coordination polymer with cobalticinium 1,1'-dicarboxylate (ccdc) incorporated in the framework has been prepared, the ccdc functioning as unique monoanionic dicarboxylate ligands. The compound shows a high redox activity based on the ccdc units.

  15. Synthesis, characterization, and antiplasmodial activity of polymer-incorporated aminoquinolines

    CSIR Research Space (South Africa)

    Aderibigbe, BA

    2014-01-01

    Full Text Available Journal of Biomedical Materials Research Part A Vol. 102(A) Synthesis, characterization, and antiplasmodial activity of polymer-incorporated aminoquinolines B. A. Aderibigbe,1 E. W. Neuse,2 E. R. Sadiku,1 S. Shina Ray,3 P. J. Smith4 1Department...

  16. Study of a novel porous gel polymer electrolyte based on thermoplastic polyurethane/poly(vinylidene fluoride-co-hexafluoropropylene) by electrospinning technique

    Science.gov (United States)

    Zhou, Ling; Cao, Qi; Jing, Bo; Wang, Xianyou; Tang, Xiaoli; Wu, Na

    2014-10-01

    A novel electrospun gel polymer electrolyte (GPE) consisting of thermoplastic polyurethane (TPU) and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) is prepared and investigated. Its characteristics are investigated by scanning electron microscopy (SEM), thermal analysis (TGA). The GPE shows a maximum ionic conductivity of 4.1 × 10-3 S cm-1 with electrochemical stability up to 5.5 V versus Li+/Li at room temperature. In addition, it shows a first charge-discharge capacity of 168.8 mAh g-1 when the gel polymer electrolyte (GPE) is evaluated in a Li/PE/LiFePO4 cell under 0.1 C-rate at the first cycle. What's more, there is microscale attenuation (1%) in the 30 cycles of charge and discharge tests. The TPU/PVDF-HFP membrane has a high tensile strength (8.4 ± 0.3 MPa) and elongation at break (118.7 ± 0.2)%. With the outstanding electrochemical and mechanical performance, it is very suitable for application in polymer lithium ion batteries.

  17. Thermodynamic analysis of sol-gel transition of gelatin in terms of water activity in various solutions.

    Science.gov (United States)

    Miyawaki, Osato; Omote, Chiaki; Matsuhira, Keiko

    2015-12-01

    Sol-gel transition of gelatin was analyzed as a multisite stoichiometric reaction of a gelatin molecule with water and solute molecules. The equilibrium sol-gel transition temperature, Tt , was estimated from the average of gelation and melting temperature measured by differential scanning calorimetry. From Tt and the melting enthalpy, ΔHsol , the equilibrium sol-to-gel ratio was estimated by the van't Hoff equation. The reciprocal form of the Wyman-Tanford equation, which describes the sol-to-gel ratio as a function of water activity, was successfully applied to obtain a good linear relationship. From this analysis, the role of water activity on the sol-gel transition of gelatin was clearly explained and the contributions of hydration and solute binding to gelatin molecules were separately discussed in sol-gel transition. The general solution for the free energy for gel-stabilization in various solutions was obtained as a simple function of solute concentration.

  18. Simulation of magnetic active polymers for versatile microfluidic devices

    CERN Document Server

    Gusenbauer, Markus; Fischbacher, Johann; Reichel, Franz; Exl, Lukas; Bance, Simon; Kataeva, Nadezhda; Binder, Claudia; Brückl, Hubert; Schrefl, Thomas

    2013-01-01

    We propose to use a compound of magnetic nanoparticles (20-100 nm) embedded in a flexible polymer (Polydimethylsiloxane PDMS) to filter circulating tumor cells (CTCs). The analysis of CTCs is an emerging tool for cancer biology research and clinical cancer management including the detection, diagnosis and monitoring of cancer. The combination of experiments and simulations lead to a versatile microfluidic lab-on-chip device. Simulations are essential to understand the influence of the embedded nanoparticles in the elastic PDMS when applying a magnetic gradient field. It combines finite element calculations of the polymer, magnetic simulations of the embedded nanoparticles and the fluid dynamic calculations of blood plasma and blood cells. With the use of magnetic active polymers a wide range of tunable microfluidic structures can be created. The method can help to increase the yield of needed isolated CTCs.

  19. Sol-gel germania triblock polymer coatings of exceptional pH stability in capillary microextraction online-coupled to high-performance liquid chromatography.

    Science.gov (United States)

    Segro, Scott S; Triplett, Judy; Malik, Abdul

    2010-05-15

    For the first time, a germania-based sol-gel coating was used in capillary microextraction (CME) in combination with high-performance liquid chromatography (HPLC). A hydroxy-terminated triblock copolymer, poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide), was covalently bonded into a sol-gel germania matrix in the course of its creation from an alkoxide precursor via hydrolytic polycondensation reactions. A thin layer of this in situ-created sol-gel hybrid material was covalently anchored to the inner walls of a 0.25 mm i.d. fused silica capillary to produce a sol-gel germania triblock polymeric sorbent in the form of a highly stable surface coating. Such a coating served as an effective extracting phase for the preconcentration of a wide range of polar and nonpolar analytes (e.g., alcohols, amines, ketones, phenols, and polycyclic aromatic hydrocarbons) with nanomolar and picomolar detection limits. Most significantly, the sol-gel germania triblock polymer coating demonstrated impressive resistance to extreme pH conditions, surviving 5 days of continuous exposure to 1.0 M HCl (pH approximately 0.0) or 1.0 M NaOH (pH approximately 14.0), practically without any changes in performance. This shows the suitability of sol-gel germania hybrid organic-inorganic hybrid materials for use as sorbents or stationary phases under extreme pH conditions, often needed in a variety of separation and sample preparation techniques and applications, including ion chromatography, hydrophobic interaction chromatography, proteomics, HPLC with electrochemical detection, isoelectric focusing, and extraction of acidic and basic analytes.

  20. Encapsulation of Polymer Colloids in a Sol-Gel Matrix. Direct-Writing of Coassembling Organic-Inorganic Hybrid Photonic Crystals.

    Science.gov (United States)

    Mikosch, Annabel; Kuehne, Alexander J C

    2016-03-22

    The spontaneous self-assembly of polymer colloids into ordered arrangements provides a facile strategy for the creation of photonic crystals. However, these structures often suffer from defects and insufficient cohesion, which result in flaking and delamination from the substrate. A coassembly process has been developed for convective assembly, resulting in large-area encapsulated colloidal crystals. However, to generate patterns or discrete deposits in designated places, convective assembly is not suitable. Here we experimentally develop conditions for direct-writing of coassembling monodisperse dye-doped polystyrene particles with a sol-gel precursor to form solid encapsulated photonic crystals. In a simple procedure the colloids are formulated in a sol-gel precursor solution, drop-cast on a flat substrate, and dried. We here establish the optimal parameters to form reproducible highly ordered photonic crystals with good optical performance. The obtained photonic crystals interact with light in the visible spectrum with a narrow optical stop-gap.

  1. Optical Control of Living Cells Electrical Activity by Conjugated Polymers.

    Science.gov (United States)

    Martino, Nicola; Bossio, Caterina; Vaquero Morata, Susana; Lanzani, Guglielmo; Antognazza, Maria Rosa

    2016-01-28

    Hybrid interfaces between organic semiconductors and living tissues represent a new tool for in-vitro and in-vivo applications. In particular, conjugated polymers display several optimal properties as substrates for biological systems, such as good biocompatibility, excellent mechanical properties, cheap and easy processing technology, and possibility of deposition on light, thin and flexible substrates. These materials have been employed for cellular interfaces like neural probes, transistors for excitation and recording of neural activity, biosensors and actuators for drug release. Recent experiments have also demonstrated the possibility to use conjugated polymers for all-optical modulation of the electrical activity of cells. Several in-vitro study cases have been reported, including primary neuronal networks, astrocytes and secondary line cells. Moreover, signal photo-transduction mediated by organic polymers has been shown to restore light sensitivity in degenerated retinas, suggesting that these devices may be used for artificial retinal prosthesis in the future. All in all, light sensitive conjugated polymers represent a new approach for optical modulation of cellular activity. In this work, all the steps required to fabricate a bio-polymer interface for optical excitation of living cells are described. The function of the active interface is to transduce the light stimulus into a modulation of the cell membrane potential. As a study case, useful for in-vitro studies, a polythiophene thin film is used as the functional, light absorbing layer, and Human Embryonic Kidney (HEK-293) cells are employed as the biological component of the interface. Practical examples of successful control of the cell membrane potential upon stimulation with light pulses of different duration are provided. In particular, it is shown that both depolarizing and hyperpolarizing effects on the cell membrane can be achieved depending on the duration of the light stimulus. The reported

  2. Tumor-tracking radiotherapy of moving targets; verification using 3D polymer gel, 2D ion-chamber array and biplanar diode array

    Energy Technology Data Exchange (ETDEWEB)

    Ceberg, Sofie; Falk, Marianne; Af Rosenschoeld, Per Munck; Cattell, Herbert; Gustafsson, Helen; Keall, Paul; Korreman, Stine S; Medin, Joakim; Nordstroem, Fredrik; Persson, Gitte; Sawant, Amit; Svatos, Michelle; Zimmerman, Jens; Baeck, Sven AJ, E-mail: sofie.ceberg@med.lu.s

    2010-11-01

    The aim of this study was to carry out a dosimetric verification of a dynamic multileaf collimator (DMLC)-based tumor-tracking delivery during respiratory-like motion. The advantage of tumor-tracking radiation delivery is the ability to allow a tighter margin around the target by continuously following and adapting the dose delivery to its motion. However, there are geometric and dosimetric uncertainties associated with beam delivery system constraints and output variations, and several investigations have to be accomplished before a clinical integration of this tracking technique. Two types of delivery were investigated in this study I) a single beam perpendicular to a target with a one dimensional motion parallel to the MLC moving direction, and II) an intensity modulated arc delivery (RapidArc (registered)) with a target motion diagonal to the MLC moving direction. The feasibility study (I) was made using an 2D ionisation chamber array and a true 3D polymer gel. The arc delivery (II) was verified using polymer gel and a biplanar diode array. Good agreement in absorbed dose was found between delivery to a static target and to a moving target with DMLC tracking using all three detector systems. However, due to the limited spatial resolution of the 2D array a detailed comparison was not possible. The RapidArc (registered) plan delivery was successfully verified using the biplanar diode array and true 3D polymer gel, and both detector systems could verify that the DMLC-based tumor-tracking delivery system has a very good ability to account for respiratory target motion.

  3. Influence of the polymer amount on bioactivity and biocompatibility of SiO{sub 2}/PEG hybrid materials synthesized by sol–gel technique

    Energy Technology Data Exchange (ETDEWEB)

    Catauro, M., E-mail: michelina.catauro@unina2.it [Department of Industrial and Information Engineering, Second University of Naples, Via Roma 29, 81031 Aversa (Italy); Bollino, F.; Papale, F. [Department of Industrial and Information Engineering, Second University of Naples, Via Roma 29, 81031 Aversa (Italy); Gallicchio, M.; Pacifico, S. [Department of Environmental Biological and Pharmaceutical Sciences and Technologies, Second University of Naples, Via Vivaldi 43, 81100 Caserta (Italy)

    2015-03-01

    SiO{sub 2}/PEG organic–inorganic hybrid materials, which differ in polyethylene glycol (PEG) content, were synthesized by sol–gel technique and the characterization of their structure and biological properties was carried out in order to evaluate the possible use in biomedical field. FT-IR spectroscopy detected that the two components of the hybrids (SiO{sub 2} and PEG) are linked by hydrogen bonds between the Si–OH groups of the inorganic phase and the terminal alcoholic groups and/or the ethereal oxygen atoms in the repeating units of polymer. X-ray diffraction analysis ascertained the amorphous nature of the gels and the observation of their morphology by SEM microscopy confirmed that the interpenetration of the two phases (organic and inorganic) occurs on nanometric scale. The biological characterization was carried out as a function of the polymer amount to study its influence on material behavior. The results showed that the synthesized materials were bioactive and biocompatible. The formation of a hydroxyapatite layer, indeed, was observed on their surface by SEM/EDX analysis after soaking in simulated body fluid. Moreover, the biocompatibility of SiO{sub 2}/PEG hybrids was assessed performing MTT and SRB cytotoxicity tests on fibroblast cell NIH 3T3 after 24 and 48 h of exposure, as well as Trypan Blue dye exclusion test. The response to the presence of the investigated materials was positive. The cell growth and proliferation showed dependence on polymer amount and time of exposure to the material extracts. Therefore, the obtained results are encouraging for the use of the obtained hybrids in dental or orthopedic applications. - Highlights: • SiO{sub 2}/PEG hybrid biomaterials synthesized by sol–gel method at various PEG percentages • Chemical and morphological characterization of hybrid materials • Chemical interactions between inorganic and organic components • Biological characterizations with MTT and SRB cytotoxicity tests

  4. Influence of superabsorbent polymers on the chemical composition of strawberry (Fragaria × ananassa Duch. and biological activity in the soil

    Directory of Open Access Journals (Sweden)

    Mikiciuk Grzegorz

    2015-06-01

    Full Text Available By improving the air and water properties of soils, superabsorbent polymers can affect the increase and improvement of the quality of the yield of berry plants, including strawberries. Their presence in the soil has an influence on its biological activity as related to microorganisms. The aim of the research was to assess the influence of superabsorbent polymers added to the soil on the content of macroelements and sodium in the leaves and fruit of strawberry of the ‘Elsanta’ cultivar and changes in the number of soil bacteria, actinomycetes and fungi. The superabsorbent polymer (AgroHydroGel was used in two doses: 1.8 and 3.6 g dm-3 of soil. The content of phosphorus, potassium, calcium, magnesium and sodium was assessed using the ASA method, while the content of nitrogen and sulphur was assessed by the elemental analysis method (CHNS analyser. The number of microorganisms was assessed with a BacTrac analyser and the coefficient of microorganism development extent (SR was also determined. AgroHydroGel increased the content of nitrogen and potassium in leaves and fruit but did not affect the content of phosphorus, sulphur and sodium. The addition of the superabsorbent at a dose of 3.6 g dm-3 of soil reduced the magnesium content both in the leaves and fruit of the strawberry. AgroHydroGel decreased the content of calcium in the fruit. The use of AgroHydroGel contributed to the expansion of the K ion ratio to other ions, both in the leaves and fruits. We observed a significant increase in the amount of soil bacteria (1.8 g dm-3 dose and no significant influence on actinomycetes and fungi (irrespective of dose used.

  5. Plasmas and atom beam activation of the surface of polymers

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Santos, C; Yubero, F; Cotrino, J; Barranco, A; Gonzalez-Elipe, A R [Instituto de Ciencia de Materiales de Sevilla (CSIC-Univ. Sevilla), Avda Americo Vespucio 49, E-41092 Sevilla (Spain)], E-mail: arge@icmse.csic.es

    2008-11-21

    Wetting properties of polyethylene terephthalate (PET) and low-density polyethylene polymers have been investigated after treatment with a microwave (MW) plasma discharge at low pressure and a dielectric barrier discharge at atmospheric pressure. Experiments have also been carried out in situ with an atom source installed in an x-ray photoemission spectrometer (XPS). The water contact angle measured on both polymers experienced a significant decrease after activation, but a progressive recovery up to different values after ageing. Standard chemical analysis by XPS showed that the plasma and oxygen beam treatments produced an increase in the concentration of -C(O){sub x} functional groups at the outermost surface layers of the treated polymers. Besides, the oxygen distribution between the topmost surface layer and the bulk has been obtained by non-destructive XPS peak shape analysis. Atomic force microscopy analysis of the surface topography showed that, except for PET treated with the MW plasma and the atom beam, the surface roughness increased after the plasma treatments. Wetting angle variations, oxygen content and distribution, surface roughness and evolution of these properties with time are comparatively discussed by taking into account the basic processes that each type of activation procedure induces in the outmost surface layers of the treated polymers.

  6. Separation of hydrolytically active components of cellulase from Myrothecium verrucaria by starch gel electrophoresis

    NARCIS (Netherlands)

    Ritter, F.J.; Prins-van der Meulen, P.Y.F.; Marel, T. van der

    1968-01-01

    Using starch gel electrophoresis according to Smithies, desalted crude cellulase from Myrothecium verrucqria was separated into at least 12 protein zones. These were tested on their activity towards p-nitrophenyl-β-D-glucoside, sodium carboxymethylcellulose and α-cellulose. They were all hydrolytica

  7. In vitro activity of Aloe vera inner gel against microorganisms grown in planktonic and sessile phases.

    Science.gov (United States)

    Cataldi, V; Di Bartolomeo, S; Di Campli, E; Nostro, A; Cellini, L; Di Giulio, M

    2015-12-01

    The failure of traditional antimicrobial treatments is becoming a worldwide problem. The use of Aloe vera is of particular interest for its role as curative agent and its efficacy in complementary therapies for a variety of illnesses. This study evaluated the antimicrobial activity of A. vera inner gel against a panel of microorganisms, Gram-positive and -negative bacteria, and Candida albicans. In addition to A. vera inner gel being used in the treatment of peptic ulcers, in dermatological treatments, and wound healing, it was also tested on the sessile phase of clinical Helicobacter pylori strains (including multi-drug-resistant strains) and on planktonic and sessile phase of Staphylococcus aureus/Pseudomonas aeruginosa clinical isolates from venous leg ulcers.A. vera inner gel expresses its prevalent activity against Gram-negative bacteria and C. albicans in respect to Gram-positive bacteria. The results of the A. vera antibiofilm activity showed a decrease of the produced biomass in a concentration-dependent-way, in each analyzed microorganism. The data obtained show that A. vera inner gel has both an antimicrobial and antibiofilm activity suggesting its potential use for the treatment of microbial infections, in particular for H. pylori gastric infection, especially in case of multi-drug-resistance, as well as for an effective wound dressing.

  8. Gel nanostructure in alkali-activated binders based on slag and fly ash, and effects of accelerated carbonation

    Energy Technology Data Exchange (ETDEWEB)

    Bernal, Susan A., E-mail: s.bernal@sheffield.ac.uk [Department of Chemical and Biomolecular Engineering, The University of Melbourne, Victoria 3010 (Australia); Department of Materials Science and Engineering, The University of Sheffield, Sheffield S1 3JD (United Kingdom); Provis, John L., E-mail: j.provis@sheffield.ac.uk [Department of Chemical and Biomolecular Engineering, The University of Melbourne, Victoria 3010 (Australia); Department of Materials Science and Engineering, The University of Sheffield, Sheffield S1 3JD (United Kingdom); Walkley, Brant; San Nicolas, Rackel [Department of Chemical and Biomolecular Engineering, The University of Melbourne, Victoria 3010 (Australia); Gehman, John D. [School of Chemistry and Bio21 Institute, The University of Melbourne, Victoria 3010 (Australia); Brice, David G.; Kilcullen, Adam R. [Department of Chemical and Biomolecular Engineering, The University of Melbourne, Victoria 3010 (Australia); Zeobond Pty Ltd, P.O. Box 23450, Docklands, Victoria 8012 (Australia); Duxson, Peter [Zeobond Pty Ltd, P.O. Box 23450, Docklands, Victoria 8012 (Australia); Deventer, Jannie S.J. van [Department of Chemical and Biomolecular Engineering, The University of Melbourne, Victoria 3010 (Australia); Zeobond Pty Ltd, P.O. Box 23450, Docklands, Victoria 8012 (Australia)

    2013-11-15

    Binders formed through alkali-activation of slags and fly ashes, including ‘fly ash geopolymers’, provide appealing properties as binders for low-emissions concrete production. However, the changes in pH and pore solution chemistry induced during accelerated carbonation testing provide unrealistically low predictions of in-service carbonation resistance. The aluminosilicate gel remaining in an alkali-activated slag system after accelerated carbonation is highly polymerised, consistent with a decalcification mechanism, while fly ash-based binders mainly carbonate through precipitation of alkali salts (bicarbonates at elevated CO{sub 2} concentrations, or carbonates under natural exposure) from the pore solution, with little change in the binder gel identifiable by nuclear magnetic resonance spectroscopy. In activated fly ash/slag blends, two distinct gels (C–A–S–H and N–A–S–H) are formed; under accelerated carbonation, the N–A–S–H gel behaves comparably to fly ash-based systems, while the C–A–S–H gel is decalcified similarly to alkali-activated slag. This provides new scope for durability optimisation, and for developing appropriate testing methodologies. -- Highlights: •C-A-S-H gel in alkali-activated slag decalcifies during accelerated carbonation. •Alkali-activated fly ash gel changes much less under CO{sub 2} exposure. •Blended slag-fly ash binder contains two coexisting gel types. •These two gels respond differently to carbonation. •Understanding of carbonation mechanisms is essential in developing test methods.

  9. Mullite fibres preparation by aqueous sol-gel process and activation energy of mullitization

    Energy Technology Data Exchange (ETDEWEB)

    Tan Hongbin, E-mail: hb-t@163.co [State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University Xi' an 710049 (China) and School of Materials Science and Engineering, Shaanxi University of Technology, Hanzhong, Shaanxi 723003 (China); Ding Yaping; Yang Jianfeng [State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University Xi' an 710049 (China)

    2010-03-04

    Mullite fibres were prepared by sol-gel process using aluminum carboxylates (ACs) and silica sol. ACs was synthesized from dissolving aluminum powder in a mixture of formic acid and oxalic acid using aluminum chloride hexahydrate as catalyst. A molar ratio of 1:2:1 for aluminum, formic acid and oxalic acid was optimized to obtain clear solution and viscous ACs sol for fibres synthesis. Thermogravimetry-differential scanning calorimetry (TG-DSC), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM) analysis were used to characterize the properties of the gel and ceramic fibres. The gel fibres completely transformed to mullite at 1200 {sup o}C, with a smooth surface and uniform diameter. The activation energy for mullite formation in precursor gel fibres was determined by means of differential thermal analysis. The value obtained, E{sub a} = 741.4 kJ/mol, was lower than most data reported in the literatures, which was attributed to the silica-alumina micro-phase separation when organic acids decomposed during gel fibres heating.

  10. Effects of laxative and nonlaxative hydrophilic polymers on canine small intestinal motor activity.

    Science.gov (United States)

    Russell, J; Bass, P

    1986-03-01

    Bulk-forming laxatives increase fecal volume and elicit aborally directed colonic motility patterns. Recently, it was demonstrated that test meals of the bulk-laxative fibers (cellulose and bran) elicited organized jejunal motor activity while nonlaxative fiber meals (guar) elicited unorganized jejunal motor activity. However, whether bulk-forming laxatives, as a class of compounds, differentially affect small intestinal motility has not been studied. Therefore, a study was made of the effects of the bulk laxatives psyllium and polycarbophil and the nonlaxative pectin on canine jejunal motor activity. Psyllium and pectin are examples of dietary fiber, while polycarbophil is a synthetic polymer. Pectin and psyllium test meals presented as viscous gels. In contrast, polycarbophil meals presented as a combination of discrete particles plus meal water. After each meal, measurements were made of the jejunal motility index, the time of reappearance of interdigestive burst activity, and overall motility patterns. Pectin and psyllium meals increased in viscosity as meal fiber content increased. As meal content and hence viscosity increased, both the laxative (psyllium) and nonlaxative (pectin) fiber meals elicited increasing jejunal motor activity and delays in the reappearance of the burst interval. For both fiber types, motor activity presented as randomly appearing contractions. In contrast, meals of the laxative polycarbophil elicited no more motor activity than the saline control meal. However, this control-level amount of activity presented as propagated clusters of contractions, ie, the "laxative-induced pattern." Polycarbophil did not delay the reappearance of burst activity.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. Measurement of Infinite Diluted Activity Coefficient of Solvents in Polymer by Inverse Gas Chromatography Method

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@1 INTRODUCTION Due to its short experimental time, little sample needed, suitable for broad temperature range, inverse gas chromatography (IGC) has been widely used to measure variety of properties of polymer systems, such as the intinite diluted activity coefficients of solvent in polymer, the glass transition temperature of polymer and the surface properties of polymer[1-5], etc. Those data have been used to develop the group contribution method for the prediction of thermodynamic proper-ties of polymer solution[6].

  12. Electro active polymers : novel bio-electrodes and implants for urinary continence

    Energy Technology Data Exchange (ETDEWEB)

    Rajagopalan, S.; Sawan, M.; Savadogo, O. [Ecole Polytechnique, Montreal, PQ (Canada). Laboratoire de nouveaux materiaux pour les systemes electrochimiques et energetiques

    2006-07-01

    This paper presented a technical solution to spinal cord injuries that result in urinary bladder dysfunction. It involves miniaturized implants based on polypyrrole, an electroactive polymer, as smart drug-eluting electrodes for neural stimulation to restore bladder function. The nerve-electrode interface is the most vulnerable point in the design and operation of neuro-electronic implants. The main disadvantages are decreased impedance and protein build-up at the stimulation site due to an inflammatory reaction. Polypyrrole is a naturally conducting polymer having both electron-conducting properties as well as actuating properties, rendering it suitable as a drug-eluting electrode for a neurostimulator. Polypyrrole electrochemically coated on platinum increases biocompatibility and reduces electric impedance by increasing the surface area of the electrode. When electrically stimulated, polypyrrole also serves as a matrix to release a negatively-charged anti-inflammatory drug fosfosal. This technology may prove useful in reconstructing a severely damaged bladder through electroactive biomaterials. Polyelectrolyte gels, such as poly(sodium) acrylate, reversibly contract and relax when activated electrically or under the influx of divalent ions. These artificial muscles can be connected to a polypyrrole strain sensor to alert the microcontroller to activate the sphincter muscle, thereby creating an artificial bladder.

  13. Grafting MAP peptide to dental polymer inhibits MMP-8 activity.

    Science.gov (United States)

    Dixit, Namrata; Settle, Jenifer K; Ye, Qiang; Berrie, Cindy L; Spencer, Paulette; Laurence, Jennifer S

    2015-02-01

    Matrix metalloproteinases (MMPs) are a class of zinc and calcium-dependent endopeptidases responsible for degrading extracellular matrix (ECM) components. Their activity is critical for both normal biological function and pathological processes (Dejonckheere et al., Cytokine Growth Factor Rev 2011;22:73-81). In dental restorations, the release and subsequent acid activation of MMPs contributes to premature failure. In particular, MMP-8 accelerates degradation by cleaving the collagen matrix within the dentin substrate in incompletely infiltrated aged bonded dentin (Buzalaf et al., Adv Dent Res 2012;24:72-76), hastening the need for replacement of restorations. Therefore, development of a dental adhesive that better resists MMP-8 activity is of significant interest. We hypothesize that modification of the polymer surface with an inhibitor would disable MMP-8 activity. Here, we identify the metal abstraction peptide (MAP) as an inhibitor of MMP-8 and demonstrate that tethering MAP to methacrylate polymers effectively inhibits catalysis. Our findings indicate complete inhibition of MMP-8 is achievable using a grafting approach. This strategy has potential to improve longevity of dental adhesives and other polymers and enable rational design of a new generation of biocompatible materials.

  14. Native gel electrophoresis of human telomerase distinguishes active complexes with or without dyskerin

    Science.gov (United States)

    Gardano, Laura; Holland, Linda; Oulton, Rena; Le Bihan, Thierry; Harrington, Lea

    2012-01-01

    Telomeres, the ends of linear chromosomes, safeguard against genome instability. The enzyme responsible for extension of the telomere 3′ terminus is the ribonucleoprotein telomerase. Whereas telomerase activity can be reconstituted in vitro with only the telomerase RNA (hTR) and telomerase reverse transcriptase (TERT), additional components are required in vivo for enzyme assembly, stability and telomere extension activity. One such associated protein, dyskerin, promotes hTR stability in vivo and is the only component to co-purify with active, endogenous human telomerase. We used oligonucleotide-based affinity purification of hTR followed by native gel electrophoresis and in-gel telomerase activity detection to query the composition of telomerase at different purification stringencies. At low salt concentrations (0.1 M NaCl), affinity-purified telomerase was ‘supershifted’ with an anti-dyskerin antibody, however the association with dyskerin was lost after purification at 0.6 M NaCl, despite the retention of telomerase activity and a comparable yield of hTR. The interaction of purified hTR and dyskerin in vitro displayed a similar salt-sensitive interaction. These results demonstrate that endogenous human telomerase, once assembled and active, does not require dyskerin for catalytic activity. Native gel electrophoresis may prove useful in the characterization of telomerase complexes under various physiological conditions. PMID:22187156

  15. Modeling the dynamics of a tracer particle in an elastic active gel.

    Science.gov (United States)

    Ben-Isaac, E; Fodor, É; Visco, P; van Wijland, F; Gov, Nir S

    2015-07-01

    The internal dynamics of active gels both in artificial (in vitro) model systems and inside the cytoskeleton of living cells has been extensively studied with experiments of recent years. These dynamics are probed using tracer particles embedded in the network of biopolymers together with molecular motors, and distinct nonthermal behavior is observed. We present a theoretical model of the dynamics of a trapped active particle, which allows us to quantify the deviations from equilibrium behavior, using both analytic and numerical calculations. We map the different regimes of dynamics in this system and highlight the different manifestations of activity: breakdown of the virial theorem and equipartition, different elasticity-dependent "effective temperatures," and distinct non-Gaussian distributions. Our results shed light on puzzling observations in active gel experiments and provide physical interpretation of existing observations, as well as predictions for future studies.

  16. Synthesis, characterization, and antiplasmodial activity of polymer-incorporated aminoquinolines.

    Science.gov (United States)

    Aderibigbe, B A; Neuse, E W; Sadiku, E R; Ray, S Shina; Smith, P J

    2014-06-01

    In this research, aminoquinoline compounds were synthesized, characterized, and incorporated into water-soluble polymers to form conjugates. The conjugates were characterized by X-ray diffraction, thermal gravimetric analysis, scanning electron microscope, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy to confirm the successful incorporation of the aminoquinoline compound on to the polymer. The synthesized conjugates were screened for in vitro antiplasmodial activity in triplet test against chloroquine-sensitive strain of Plasmodium falciparum and chloroquine drug was used as a reference drug in all the experiments. A full dose-response was performed to determine the concentration inhibiting 50% of parasite growth (IC50 value). Polymeric conjugates containing 3-diethylamino-1-propylamine solubilizing units were found to be most active against the chloroquine-sensitive strain of P. falciparum.

  17. Polymer application for separation/filtration of biological active compounds

    Science.gov (United States)

    Tylkowski, B.; Tsibranska, I.

    2017-06-01

    Membrane technology is an important part of the engineer's toolbox. This is especially true for industries that process food and other products with their primary source from nature. This review is focused on ongoing development work using membrane technologies for concentration and separation of biologically active compounds, such as polyphenols and flavonoids. We provide the readers not only with the last results achieve in this field but also, we deliver detailed information about the membrane types and polymers used for their preparation.

  18. Development of Curcumin loaded chitosan polymer based nanoemulsion gel: In vitro, ex vivo evaluation and in vivo wound healing studies.

    Science.gov (United States)

    Thomas, Lydia; Zakir, Foziyah; Mirza, Mohd Aamir; Anwer, Md Khalid; Ahmad, Farhan Jalees; Iqbal, Zeenat

    2017-03-16

    In the present study, various nanoemulsions were prepared using Labrafac PG+Triacetin as oil, Tween 80 as a surfactant and polyethylene glycol (PEG 400) as a co-surfactant. The developed nanoemulsions (NE1-NE5) were evaluated for physicochemical characterizations and ex-vivo for skin permeation and deposition studies. The highest skin deposition was observed for NE2 with 46.07% deposition amongst all developed nanoemulsions (NE1-NE5). Optimized nanoemulsion (NE2) had vesicle size of 84.032±0.023nm, viscosity 78.23±22.2 cps, refractive index 1.404. Nanoemulsion gel were developed by incorporation of optimized nanoemulsion (NE2) into 1-3% chitosan and characterized by physical evaluation and rheological studies. Chitosan gel (2%) was found to be suitable for gelation of nanoemulsion based on its consistency, feel and ease of spreadability. The flux of nanoemulsion gel was found 68.88μg/cm(2)/h as compared to NE2 (76.05μg/cm(2)/h) is significantly lower suggesting limited skin permeation of curcumin form gel. However, the retained amount of curcumin on skin by gel formulation (980.75±88μg) is significantly higher than NE2 (771.25±67μg). Enhanced skin permeation of NE2 (46.07%) was observed when compared to nanoemulsion gel (31.25%) and plain gel (11.47%). The outcome of this study evidently points out the potential of curcumin entrapped nanoemulsion gel in wound healing.

  19. Li/LiFePO4 batteries with gel polymer electrolytes incorporating a guanidinium-based ionic liquid cycled at room temperature and 50 °C

    Science.gov (United States)

    Li, Mingtao; Yang, Li; Fang, Shaohua; Dong, Siming; Jin, Yide; Hirano, Shin-ichi; Tachibana, Kazuhiro

    2011-08-01

    Gel polymer electrolytes composed of PVdF-HFP microporous membrane incorporating a guanidinium-based ionic liquid with 0.8 mol kg-1 lithium bis(trifluoromethanesulfonylimide) are characterized as the electrolytes in Li/LiFePO4 batteries. The ionic conductivity of these gel polymer electrolytes is 3.16 × 10-4 and 8.32 × 10-4 S cm-1 at 25 and 50 °C, respectively. The electrolytes show good interfacial stability towards lithium metal and high oxidation stability, and the decomposition potential reaches 5.3 and 4.6 V (vs. Li/Li+) at 25 and 50 °C, respectively. Li/LiFePO4 cells using the PVdF-HFP/1g13TFSI-LiTFSI electrolytes show good discharge capacity and cycle stability, and no significant loss in discharge capacity of the battery is observed over 100 cycles. The cells deliver the capacity of 142 and 150 mAh g-1 at the 100th cycling at 25 and 50 °C, respectively.

  20. Transformation of metal-organic framework to polymer gel by cross-linking the organic ligands preorganized in metal-organic framework.

    Science.gov (United States)

    Ishiwata, Takumi; Furukawa, Yuki; Sugikawa, Kouta; Kokado, Kenta; Sada, Kazuki

    2013-04-10

    Until now, seamless fusion of metal-organic frameworks (MOFs) and covalently cross-linked polymer gels (PG) at molecular level has been extremely rare, since these two matters have been regarded as opposite, that is, hard versus soft. In this report, we demonstrate transformation of cubic MOF crystals to PG via inner cross-linking of the organic linkers in the void space of MOF, followed by decomposition of the metal coordination. The obtained PG behaved as a polyelectrolyte gel, indicating the high content of ionic groups inside. Metal ions were well adsorbed in the PG due to its densely packed carboxylate groups. A chimera-type hybrid material consisting of MOF and PG was obtained by partial hydrolysis of resulting cross-linked MOF. The shape of resulting PG network well reflected the crystal structure of MOF employed as a template. Our results will connect the two different network materials that have been ever studied in the two different fields to provide new soft and hard hybrid materials, and the unique copolymerization in the large void space of the MOF will open a new horizon toward "ideal network polymers" never prepared before now.

  1. In vitro activity of Aloe vera inner gel against Helicobacter pylori strains.

    Science.gov (United States)

    Cellini, L; Di Bartolomeo, S; Di Campli, E; Genovese, S; Locatelli, M; Di Giulio, M

    2014-07-01

    Aloe barbadensis Miller (Aloe vera) is a herbal remedy widely used for a variety of illnesses; A. vera leaf extracts have been promoted for detoxification, cure constipation, help flush out toxins and wastes from the body, promote digestion and are used in the treatment of peptic ulcer for cytoprotective action. The aim of this study was to evaluate the antibacterial activity of A. vera inner gel against both susceptible and resistant Helicobacter pylori strains isolated in Abruzzo region, Italy. The inner gel of leaves of a 5-year-old plant of A. vera was extracted, homogenized and tested from 800 to 1.56 mg ml(-1) against 14 clinical strains and one reference strain of H. pylori using the broth microdilution methodology. Furthermore, the sample of A. vera was investigated for the chemical fingerprint of anthraquinones. The inhibitory concentrations of A. vera inner gel were similar to the bactericidal ones, with values ranging from 6.25 to 800 mg ml(-1) . Fifty per cent of the detected strains, independently of their susceptibility profile, were inhibited in their growth at 100 mg ml(-1) . Aloe vera inner gel expresses antibacterial properties against H. pylori and, therefore, in combination with antibiotics, could represent a novel strategy for the treatment of the infection of H. pylori, especially in cases of multiresistance. The study demonstrates that the Aloe vera inner gel expresses antibacterial properties against both susceptible and resistant Helicobacter pylori strains. These findings may impact on the antimicrobial resistance phenomenon of H. pylori, proposing the A. vera inner gel as a novel effective natural agent for combination with antibiotics for the treatment of H. pylori gastric infection. © 2014 The Society for Applied Microbiology.

  2. Comprehensive bactericidal activity of an ethanol-based hand gel in 15 seconds.

    Science.gov (United States)

    Kampf, Günter; Hollingsworth, Angela

    2008-01-22

    Some studies indicate that the commonly recommended 30 s application time for the post contamination treatment of hands may not be necessary as the same effect may be achieved with some formulations in a shorter application time such as 15 s. We evaluated the bactericidal activity of an ethanol-based hand gel (Sterillium Comfort Gel) within 15 s in a time-kill-test against 11 Gram-positive, 16 Gram-negative bacteria and 11 emerging bacterial pathogens. Each strain was evaluated in quadruplicate. The hand gel (85% ethanol, w/w) was found to reduce all 11 Gram-positive and all 16 Gram-negative bacteria by more than 5 log10 steps within 15 s, not only against the ATCC test strains but also against corresponding clinical isolates. In addition, a log10 reduction > 5 was observed against all tested emerging bacterial pathogens. The ethanol-based hand gel was found to have a broad spectrum of bactericidal activity in only 15 s which includes the most common species causing nosocomial infections and the relevant emerging pathogens. Future research will hopefully help to find out if a shorter application time for the post contamination treatment of hands provides more benefits or more risks.

  3. Comprehensive bactericidal activity of an ethanol-based hand gel in 15 seconds

    Directory of Open Access Journals (Sweden)

    Kampf Günter

    2008-01-01

    Full Text Available Abstract Background Some studies indicate that the commonly recommended 30 s application time for the post contamination treatment of hands may not be necessary as the same effect may be achieved with some formulations in a shorter application time such as 15 s. Method We evaluated the bactericidal activity of an ethanol-based hand gel (Sterillium® Comfort Gel within 15 s in a time-kill-test against 11 Gram-positive, 16 Gram-negative bacteria and 11 emerging bacterial pathogens. Each strain was evaluated in quadruplicate. Results The hand gel (85% ethanol, w/w was found to reduce all 11 Gram-positive and all 16 Gram-negative bacteria by more than 5 log10 steps within 15 s, not only against the ATCC test strains but also against corresponding clinical isolates. In addition, a log10 reduction > 5 was observed against all tested emerging bacterial pathogens. Conclusion The ethanol-based hand gel was found to have a broad spectrum of bactericidal activity in only 15 s which includes the most common species causing nosocomial infections and the relevant emerging pathogens. Future research will hopefully help to find out if a shorter application time for the post contamination treatment of hands provides more benefits or more risks.

  4. Effect of The Addition of PEG and PVA Polymer for Gel Electrolytes in Dye-Sensitized Solar Cell (DSSC) with Chlorophyll as Dye Sensitizer

    Science.gov (United States)

    Seni, Ramadhanti S.; Puspitasari, Nurrisma; Endarko

    2017-07-01

    Dye-sensitized Solar Cell (DSSC) is a third-generation solar cell that consists of a working electrode, electrolyte and counter electrode. One of the most important parts of DSSC is an electrolyte that roles as a medium and regenerates the electron transport of electrons in the dye. However, the liquid electrolyte has a lack of stability in long-term use and easily evaporate or leak in DSSC. Therefore, this study aims to investigate an effect of the addition of polymer material such as PEG 1000, 4000 and PVA 60000 for fabricating a gel electrolyte to solve the problems of liquid electrolyte. The synthesized TiO2 nanoparticles used in this study was prepared using co-precipitation (CPT) method which produces TiO2 anatase phase with a crystal size of 11.1 nm. DSSC has been successfully conducted and analyzed to evaluate its performance. The results showed that the efficiency of DSSC cells using gel electrolyte prepared with PVA 60000 was better than a liquid electrolyte, PEG 1000, 4000, with the efficiency could be obtained at 0.083, 0.018, 0.033, and 0.054%, respectively. The results demonstrated that the addition PEG and/or PVA could be enhanced the performance of DSSC due to gel electrolyte produced current and voltage more stable compared to the liquid electrolyte.

  5. Performance evaluation of an improved optical computed tomography polymer gel dosimeter system for 3D dose verification of static and dynamic phantom deliveries.

    Science.gov (United States)

    Lopatiuk-Tirpak, O; Langen, K M; Meeks, S L; Kupelian, P A; Zeidan, O A; Maryanski, M J

    2008-09-01

    The performance of a next-generation optical computed tomography scanner (OCTOPUS-5X) is characterized in the context of three-dimensional gel dosimetry. Large-volume (2.2 L), muscle-equivalent, radiation-sensitive polymer gel dosimeters (BANG-3) were used. Improvements in scanner design leading to shorter acquisition times are discussed. The spatial resolution, detectable absorbance range, and reproducibility are assessed. An efficient method for calibrating gel dosimeters using the depth-dose relationship is applied, with photon- and electron-based deliveries yielding equivalent results. A procedure involving a preirradiation scan was used to reduce the edge artifacts in reconstructed images, thereby increasing the useful cross-sectional area of the dosimeter by nearly a factor of 2. Dose distributions derived from optical density measurements using the calibration coefficient show good agreement with the treatment planning system simulations and radiographic film measurements. The feasibility of use for motion (four-dimensional) dosimetry is demonstrated on an example comparing dose distributions from static and dynamic delivery of a single-field photon plan. The capability to visualize three-dimensional dose distributions is also illustrated.

  6. High performance solid-state electric double layer capacitor from redox mediated gel polymer electrolyte and renewable tamarind fruit shell derived porous carbon.

    Science.gov (United States)

    Senthilkumar, S T; Selvan, R Kalai; Melo, J S; Sanjeeviraja, C

    2013-11-13

    The activated carbon was derived from tamarind fruit shell and utilized as electrodes in a solid state electrochemical double layer capacitor (SSEDLC). The fabricated SSEDLC with PVA (polyvinyl alcohol)/H2SO4 gel electrolyte delivered high specific capacitance and energy density of 412 F g(-1) and 9.166 W h kg(-1), respectively, at 1.56 A g(-1). Subsequently, Na2MoO4 (sodium molybdate) added PVA/H2SO4 gel electrolyte was also prepared and applied for SSEDLC, to improve the performance. Surprisingly, 57.2% of specific capacitance (648 F g(-1)) and of energy density (14.4 Wh kg(-1)) was increased while introducing Na2MoO4 as the redox mediator in PVA/H2SO4 gel electrolyte. This improved performance is owed to the redox reaction between Mo(VI)/Mo(V) and Mo(VI)/Mo(IV) redox couples in Na2MoO4/PVA/H2SO4 gel electrolyte. Similarly, the fabricated device shows the excellent capacitance retention of 93% for over 3000 cycles. The present work suggests that the Na2MoO4 added PVA/H2SO4 gel is a potential electrolyte to improve the performance instead of pristine PVA/H2SO4 gel electrolyte. Based on the overall performance, it is strongly believed that the combination of tamarind fruit shell derived activated carbon and Na2MoO4/PVA/H2SO4 gel electrolyte is more attractive in the near future for high performance SSEDLCs.

  7. Transbuccal permeation, anti-inflammatory activity and clinical efficacy of piroxicam formulated in different gels.

    Science.gov (United States)

    Attia, M A; El-Gibaly, I; Shaltout, S E; Fetih, G N

    2004-05-19

    In attempts to avoid the systemic side effects of piroxicam (PC) (e.g. gastrotoxicity), several buccal gel formulations containing PC were prepared and their effects on the characteristics of the drug permeation through rabbit buccal mucosa in-vitro were evaluated using a Franz-type diffusion cell. The general rank order of the total flux of 0.5% PC from gels was found to be: hydroxypropylmethylcellulose (HPMC, 2.5%) > hydroxypropylcellulose (HPC, 2.5%) >or= sodium alginate (Na alg., 7%) > methylcellulose (MC, 3%) > hydroxyethylcellulose (HEC, 1.5%) > carbopol 934 (Carb. 934, 1%) >or= sodium carboxymethylcellulose (NaCMC, 2%) > pluronic F-127 (PF-127, 20%) > polyvinyl alcohol (PVA, 10%). The effect of various penetration enhancers 1% sodium lauryl sulphate (NaLS), 3% sodium deoxycholate (NaDC), 3% sodium tauroglycocholate (NaTGC) on the rate of permeation across the excised buccal mucosa (of 0.5% PC in gels prepared using 3% MC, 2.5% HPMC or 7% Na alg. base) and histology of the buccal epithelium was also investigated. Pharmacodynamic evaluation of the anti-inflammatory activity of PC in these gel formulations (containing 3% NaDC as an enhancer) was carried out using the kaolin-induced rat paw oedema method. The results obtained indicated that PC administered in 7% Na alg. or 2.5% HPMC gel bases was significantly more effective than the 3% MC gel and oral drug solution in suppressing oedema formation in rats. Comparative clinical studies were conducted in patients with post-operative dental pain and oedema following maxillofacial operations. The results revealed that 7% Na alg. and 2.5% HPMC gel formulations applied to the buccal mucosa were slightly better than or equally effective to the orally administered commercial product (Feldene Flash) tablet) in reducing pain level, swelling and tenderness within a period of 4 days. These findings suggest that PC (0.5%) administered in the buccal gel may present a potential therapeutical use as a strong anti

  8. A Novel Brucine Gel Transdermal Delivery System Designed for Anti-Inflammatory and Analgesic Activities

    Directory of Open Access Journals (Sweden)

    Ping Wu

    2017-04-01

    Full Text Available The seeds of Strychnos nux-vomica L., as a traditional Chinese medicine, have good anti-inflammatory and analgesic activities. However, it usually leads to gastrointestinal irritation and systemic toxicity via oral administration. In the study, it was discovered that a novel gel transdermal delivery system contained brucine, the main effective component extracted from Strychnos nux-vomica. Results showed that the brucine gel system inhibited arthritis symptoms and the proliferation of the synoviocytes in the rat adjuvant arthritis model, which indicated its curative effect for rheumatoid arthritis. Meanwhile, it significantly relieved the xylene-induced ear edema in the mouse ear swelling test, which manifested its anti-inflammatory property. Moreover, the brucine gel eased the pain of paw formalin injection in the formalin test, which demonstrated its analgesic effects. In addition, the brucine significantly inhibited lipopolysaccharide (LPS-induced Prostaglandin E2 (PGE2 production without affecting the viability of cell in vitro anti-inflammatory test, which proved that its anti-inflammatory and analgesic actions were related to inhibition of prostaglandin synthesis. It is suggested that the brucine gel is a promising vehicle for transdermal delivery on the treatment of inflammatory disease.

  9. Enhanced catalytic activity of gold nanoparticles doped in a mesoporous organic gel based on polymeric phloroglucinol carboxylic acid-formaldehyde.

    Science.gov (United States)

    Yang, Han; Nagai, Keiji; Abe, Toshiyuki; Homma, Hirofumi; Norimatsu, Takayoshi; Ramaraj, Ramasamy

    2009-09-01

    Gold nanoparticles were supported by a phloroglucinolcarboxylic acid-formaldehyde (PF) gel, a new organic gel with a 30 nm spheroid-like structure. The surface area of the PF gel with gold nanoparticles was 550 m(2)/g. Gold nanoparticles supported on a PF gel exhibited catalytic activity in the reduction of 4-nitrophenol with a reaction rate constant of 7.4 x 10(-3) s(-1), which is high in the reported heterogeneous reaction system. The adsorption behavior of 4-nitrophenol into the gel support was observed by ultraviolet-visible absorption spectroscopy. Gold nanoparticles in the PF network were characterized by scanning electron microscopy, atomic force microscopy, and transmission electron microscopy observation. The high reduction rate would be attributed to the extraction and diffusion of the reactant through the pores of a PF gel support to encounter the highly dispersed gold nanoparticles on the surface and inside the material.

  10. {sup 7}Li NMR spectroscopy and ion conduction mechanism of composite gel polymer electrolyte: A comparative study with variation of salt and plasticizer with filler

    Energy Technology Data Exchange (ETDEWEB)

    Saikia, D. [Department of Chemistry, Center for Nanotechnology and R and D Center for Membrane Technology, Chung Yuan Christian University, Chung Li 32023, Taiwan (China); Chen-Yang, Y.W. [Department of Chemistry, Center for Nanotechnology and R and D Center for Membrane Technology, Chung Yuan Christian University, Chung Li 32023, Taiwan (China)], E-mail: yuiwhei@cycu.edu.tw; Chen, Y.T.; Li, Y.K.; Lin, S.I. [Department of Chemistry, Center for Nanotechnology and R and D Center for Membrane Technology, Chung Yuan Christian University, Chung Li 32023, Taiwan (China)

    2009-01-30

    Microporous composite gel polymer electrolyte (CGPE) has been prepared by incorporating the home-made silica aerogel (SAG) particles into the poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) copolymer/LiClO{sub 4} matrix. The ionic transport behavior of the electrolyte is studied with various experimental techniques such as AC impedance, X-ray diffraction (XRD), infrared (IR) spectra, nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA), etc. The results reveal that the SAG particles are well dispersed in the electrolytes and incorporate with the other components of the CGPEs. The solid-state {sup 7}Li NMR study has confirmed the interactions of lithium ion with SAG, polymer and plasticizers, causing to form the microporous structure and reduce the glass transition temperature and crystallinity, resulting in an increase in ionic conductivity of the CGPE. The best ionic conductivity (1.04 x 10{sup -2} S/cm at room temperature) is obtained from the composite polymer electrolyte containing 4 wt% of SAG, which is approximately four times higher than the ionic conductivity of the electrolyte without the filler.

  11. Low-voltage large-current ion gel gated polymer transistors fabricated by a "cut and bond" process.

    Science.gov (United States)

    Shao, Xianyi; Bao, Bei; Zhao, Jiaqing; Tang, Wei; Wang, Shun; Guo, Xiaojun

    2015-03-04

    A "cut and bond" process using a commercial die bonder was developed for fabricating ion gel gated organic thin-film transistors (OTFTs). It addresses the issues of damaging or contaminating the channel layer when depositing the ion gel layer on top in conventional fabrication processes. The formed isolated dielectric regions can help to eliminate possible lateral electric field coupling through the dielectric layer when several devices are integrated to construct functional circuits. The fabricated OTFTs provide mA-level ON current, and an ON/OFF current ratio higher than 10(5) with the gate swing voltage of less than 3 V. With the developed process, the ion gel OTFTs are integrated with inorganic light emitting diodes (LEDs) of different colors on plastic substrate using the same die bonder, and the light emission of the LEDs can be modulated in a wide range from dark to high brightness with change of the gate voltage less than 3 V.

  12. Improved detection of amylase activity by sodium dodecyl sulfate-polyacrylamide gel electrophoresis with copolymerized starch.

    Science.gov (United States)

    Martínez, T F; Alarcón, F J; Díaz-López, M; Moyano, F J

    2000-08-01

    An improved method, based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for detection of amylase activity is described. This method will allow better characterization of certain amylases than that obtained by the Davis technique. The main features of the technique are: (i) identification of amylase bands and molecular mass determination are possible in the same gel; (ii) the hydrolysis of copolymerized substrate during electrophoretic separation is prevented using very low temperatures instead of inactivating agents such as chelating agents; and (iii) the technique is applicable to reveal amylase activity in a wide range of biological samples. The method is not useful for enzymes sensitive to SDS and for high molecular mass amylases.

  13. In vitro and in vivo antioxidant activities of polysaccharide purified from aloe vera (Aloe barbadensis) gel.

    Science.gov (United States)

    Kang, Min-Cheol; Kim, Seo Young; Kim, Yoon Taek; Kim, Eun-A; Lee, Seung-Hong; Ko, Seok-Chun; Wijesinghe, W A J P; Samarakoon, Kalpa W; Kim, Young-Sun; Cho, Jin Hun; Jang, Hyeang-Su; Jeon, You-Jin

    2014-01-01

    The in vitro and in vivo antioxidant potentials of a polysaccharide isolated from aloe vera gel were investigated. Enzymatic extracts were prepared from aloe vera gel by using ten digestive enzymes including five carbohydrases and five proteases. Among them, the highest yield was obtained with the Viscozyme extract and the same extract showed the best radical scavenging activity. An active polysaccharide was purified from the Viscozyme extract using ethanol-added separation and anion exchange chromatography. Purified aloe vera polysaccharide (APS) strongly scavenged radicals including DPPH, hydroxyl and alkyl radicals. In addition, APS showed a protective effect against AAPH-induced oxidative stress and cell death in Vero cells as well as in the in vivo zebrafish model. In this study, it is proved that both the in vitro and in vivo antioxidant potentials of APS could be further utilized in relevant industrial applications.

  14. Fucoidan is the active component of fucus vesiculosus that promotes contraction of fibroblast-populated collagen gels.

    Science.gov (United States)

    Fujimura, T; Shibuya, Y; Moriwaki, S; Tsukahara, K; Kitahara, T; Sano, T; Nishizawa, Y; Takema, Y

    2000-10-01

    The fibroblast-populated collagen gel culture method has been evaluated as a dermal model of wound contraction and granulation in tissues during the wound healing process and as an in vitro model of dermal tissue. We previously reported that an extract of Fucus vesiculosus promoted fibroblast-populated collagen gel contraction and that the promotion of the gel contraction was due to the increased expression of integrin alpha2beta1 on the surface of the fibroblasts. In this study, we investigated the active component of the extract of this alga using extraction and fractionation techniques. Water extraction of the alga was followed by precipitation with excess ethanol and then gel filtration with the boundary molecular weight of 30,000. The high molecular weight fraction obtained from gel filtration was fractionated by ion exchange chromatography on diethylaminoethyl cellulose column to give active fractions that have more polar properties. These polar, high molecular weight fractions which contained molecules with fucose and sulfate groups showed significant gel contraction-promoting activity and integrin expression-enhancing activity, and were estimated to be the sulfated-polysaccharide fucoidan. Commercially available fucoidan showed similar activities to the above-described fraction of this alga. Although it remains necessary to precisely identify the specific active component, the above results indicate that fucoidan is the active component which promotes collagen gel contraction, and also indicate the possibility that it dose so by enhancing the integrin alpha2beta1 expression.

  15. Anti-HIV-1 activity of anionic polymers: a comparative study of candidate microbicides

    Directory of Open Access Journals (Sweden)

    Li Yun-Yao

    2002-11-01

    Full Text Available Abstract Background Cellulose acetate phthalate (CAP in soluble form blocks coreceptor binding sites on the virus envelope glycoprotein gp120 and elicits gp41 six-helix bundle formation, processes involved in virus inactivation. CAP is not soluble at pH Methods Enzyme linked immunosorbent assays (ELISA were used to (1 study HIV-1 IIIB and BaL binding to micronized CAP; (2 detect virus disintegration; and (3 measure gp41 six-helix bundle formation. Cells containing integrated HIV-1 LTR linked to the β-gal gene and expressing CD4 and coreceptors CXCR4 or CCR5 were used to measure virus infectivity. Results 1 HIV-1 IIIB and BaL, respectively, effectively bound to micronized CAP. 2 The interaction between HIV-1 and micronized CAP led to: (a gp41 six-helix bundle formation; (b virus disintegration and shedding of envelope glycoproteins; and (c rapid loss of infectivity. Polymers other than CAP, except Carbomer 974P, elicited gp41 six-helix bundle formation in HIV-1 IIIB but only poly(napthalene sulfonate, in addition to CAP, had this effect on HIV-1 BaL. These polymers differed with respect to their virucidal activities, the differences being more pronounced for HIV-1 BaL. Conclusions Micronized CAP is the only candidate topical microbicide with the capacity to remove rapidly by adsorption from physiological fluids HIV-1 of both the X4 and R5 biotypes and is likely to prevent virus contact with target cells. The interaction between micronized CAP and HIV-1 leads to rapid virus inactivation. Among other anionic polymers, cellulose sulfate, BufferGel and aryl sulfonates appear most effective in this respect.

  16. Photocatalytic activity of titania coatings synthesised by a combined laser/sol–gel technique

    Energy Technology Data Exchange (ETDEWEB)

    Adraider, Y. [School of Science and Engineering, Teesside University, Middlesbrough TS1 3BA (United Kingdom); Pang, Y.X., E-mail: F6098038@tees.ac.uk [School of Science and Engineering, Teesside University, Middlesbrough TS1 3BA (United Kingdom); Nabhani, F.; Hodgson, S.N. [School of Science and Engineering, Teesside University, Middlesbrough TS1 3BA (United Kingdom); Sharp, M.C.; Al-Waidh, A. [General Engineering Research Institute, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF (United Kingdom)

    2014-06-01

    Highlights: • Sol–gel method was used to prepare titania coatings. • Titania thin films were coated on substrate surface by dip coating. • Fibre laser was employed to irradiate the titania coated surfaces. • Photocatalytic efficiency of titania coatings was significantly improved after laser processing. - Abstract: Titania coatings were prepared using sol–gel method and then applied on the substrate surface by dip coating. Fibre laser (λ = 1064 nm) in continuous wave mode was used to irradiate the titania coated surfaces at different specific energies. The ATR-FTIR, XRD, SEM, EDS and contact angle measurement were employed to analyse surface morphology, phase composition and crystalline structure of laser-irradiated titania coatings, whilst the photocatalytic activity was evaluated by measuring the decomposition of methylene blue (MB) after exposure to the visible light for various illumination times. Results showed that the laser-irradiated titania coatings demonstrate significant different composition and microstructure in comparison with the as-coated from the same sol–gel titania. Photocatalytic efficiency of titania coatings was significantly improved after laser processing. The photocatalytic activity of laser-irradiated titania coatings was higher than that of the as-coated titania. The titania coating processed at laser specific energy of 6.5 J/mm{sup 2} exhibited the highest photocatalytic activity among all titania samples.

  17. AC Electric Field Activated Shape Memory Polymer Composite

    Science.gov (United States)

    Kang, Jin Ho; Siochi, Emilie J.; Penner, Ronald K.; Turner, Travis L.

    2011-01-01

    Shape memory materials have drawn interest for applications like intelligent medical devices, deployable space structures and morphing structures. Compared to other shape memory materials like shape memory alloys (SMAs) or shape memory ceramics (SMCs), shape memory polymers (SMPs) have high elastic deformation that is amenable to tailored of mechanical properties, have lower density, and are easily processed. However, SMPs have low recovery stress and long response times. A new shape memory thermosetting polymer nanocomposite (LaRC-SMPC) was synthesized with conductive fillers to enhance its thermo-mechanical characteristics. A new composition of shape memory thermosetting polymer nanocomposite (LaRC-SMPC) was synthesized with conductive functionalized graphene sheets (FGS) to enhance its thermo-mechanical characteristics. The elastic modulus of LaRC-SMPC is approximately 2.7 GPa at room temperature and 4.3 MPa above its glass transition temperature. Conductive FGSs-doped LaRC-SMPC exhibited higher conductivity compared to pristine LaRC SMP. Applying an electric field at between 0.1 Hz and 1 kHz induced faster heating to activate the LaRC-SMPC s shape memory effect relative to applying DC electric field or AC electric field at frequencies exceeding1 kHz.

  18. SU-E-CAMPUS-T-05: Validation of High-Resolution 3D Patient QA for Proton Pencil Beam Scanning and IMPT by Polymer Gel Dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Cardin, A; Avery, S; Ding, X; Kassaee, A; Lin, L [University of Pennsylvania, Philadelphia, PA (United States); Maryanski, M [MGS Research, Inc., Madison, CT (United States)

    2014-06-15

    Purpose: Validation of high-resolution 3D patient QA for proton pencil beam scanning and IMPT by polymer gel dosimetry. Methods: Four BANG3Pro polymer gel dosimeters (manufactured by MGS Research Inc, Madison, CT) were used for patient QA at the Robert's Proton Therapy Center (RPTC, Philadelphia, PA). All dosimeters were sealed in identical thin-wall Pyrex glass spheres. Each dosimeter contained a set of markers for 3D registration purposes. The dosimeters were mounted in a consistent and reproducible manner using a custom build holder. Two proton pencil beam scanning plans were designed using Varian Eclipse™ treatment planning system: 1) A two-field intensity modulated proton therapy (IMPT) plan and 2) one single field uniform dose (SFUD) plan. The IMPT fields were evaluated as a composite plan and individual fields, the SFUD plan was delivered as a single field plan.Laser CT scanning was performed using the manufacturer's OCTOPUS-IQ axial transmission laser CT scanner using a 1 mm slice thickness. 3D registration, analysis, and OD/cm to absorbed dose calibrations were perfomed using DICOM RT-Dose and CT files, and software developed by the manufacturer. 3D delta index, a metric equivalent to the gamma tool, was used for dose comparison. Results: Very good agreement with single IMPT fields and with SFUD was obtained. Composite IMPT fields had a less satisfactory agreement. The single fields had 3D delta index passing rates (3% dose difference, 3 mm DTA) of 98.98% and 94.91%. The composite 3D delta index passing rate was 80.80%. The SFUD passing rate was 93.77%. Required shifts of the dose distributions were less than 4 mm. Conclusion: A formulation of the BANG3Pro polymer gel dosimeter, suitable for 3D QA of proton patient plans is established and validated. Likewise, the mailed QA analysis service provided by the manufacturer is a practical option when required resources are unavailable. We fully disclose that the subject of this research regards a

  19. Redox Active Polymers as Soluble Nanomaterials for Energy Storage.

    Science.gov (United States)

    Burgess, Mark; Moore, Jeffrey S; Rodríguez-López, Joaquín

    2016-11-15

    It is an exciting time for exploring the synergism between the chemical and dimensional properties of redox nanomaterials for addressing the manifold performance demands faced by energy storage technologies. The call for widespread adoption of alternative energy sources requires the combination of emerging chemical concepts with redesigned battery formats. Our groups are interested in the development and implementation of a new strategy for nonaqueous flow batteries (NRFBs) for grid energy storage. Our motivation is to solve major challenges in NRFBs, such as the lack of membranes that simultaneously allow fast ion transport while minimizing redox active species crossover between anolyte (negative electrolyte) and catholyte (positive electrolyte) compartments. This pervasive crossover leads to deleterious capacity fade and materials underutilization. In this Account, we highlight redox active polymers (RAPs) and related polymer colloids as soluble nanoscopic energy storing units that enable the simple but powerful size-exclusion concept for NRFBs. Crossover of the redox component is suppressed by matching high molecular weight RAPs with simple and inexpensive nanoporous commercial separators. In contrast to the vast literature on the redox chemistry of electrode-confined polymer films, studies on the electrochemistry of solubilized RAPs are incipient. This is due in part to challenges in finding suitable solvents that enable systematic studies on high polymers. Here, viologen-, ferrocene- and nitrostyrene-based polymers in various formats exhibit properties that make amenable their electrochemical exploration as solution-phase redox couples. A main finding is that RAP solutions store energy efficiently and reversibly while offering chemical modularity and size versatility. Beyond the practicality toward their use in NRFBs, the fundamental electrochemistry exhibited by RAPs is fascinating, showing clear distinctions in behavior from that of small molecules. Whereas

  20. Protein composition of wheat gluten polymer fractions determined by quantitative two-dimensional gel electrophoresis and tandem mass spectrometry

    Science.gov (United States)

    Flour proteins from the US bread wheat Butte 86 were extracted in 0.5% SDS using a two-step procedure with and without sonication and further separated by size exclusion chromatography into monomeric and polymeric fractions. Proteins in each fraction were analyzed by quantitative two-dimensional gel...

  1. Lipophilic super-absorbent polymer gels as surface cleaners for oil and grease from metal and non-metal surfaces

    Science.gov (United States)

    The objective of this research is to develop a new cleaning technology based on lipophilic super-absorbent swelling gels for the removal of oil, grease and particulate matters from metal and non-metal surfaces. It is desired that the cleaner is in solid form and is VOC-exempt, HAP-free, non-toxic, n...

  2. Increasing the activity and enantioselectivity of lipases by sol-gel immobilization: further advancements of practical interest.

    Science.gov (United States)

    Tielmann, Patrick; Kierkels, Hans; Zonta, Albin; Ilie, Adriana; Reetz, Manfred T

    2014-06-21

    The entrapment of lipases in hydrophobic silicate matrices formed by sol-gel mediated hydrolysis of RSi(OCH3)3/Si(OCH3)4 as originally reported in 1996 has been improved over the years by a number of modifications. In the production of second-generation sol-gel lipase immobilizates, a variety of additives during the sol-gel process leads to increased activity and enhanced stereoselectivity in esterifying kinetic resolution. Recent advances in this type of lipase immobilization are reviewed here, in addition to new results regarding the sol-gel entrapment of the lipase from Burkholderia cepacia. It constitutes an excellent heterogeneous biocatalyst in the acylating kinetic resolution of two synthetically and industrially important chiral alcohols, rac-sulcatol and rac-trans-2-methoxycyclohexanol. The observation that the catalyst can be used 10 times in recycling experiments without losing its significant activity or enantioselectivity demonstrates the practical viability of the sol-gel approach.

  3. Gel Polymer Electrolytes for Lithium Ion Batteries%锂离子电池用凝胶聚合物电解质研究进展

    Institute of Scientific and Technical Information of China (English)

    关红艳; 连芳; 仇卫华; 孙加林

    2012-01-01

    凝胶聚合物电解质既具有固态聚合物电解质良好的力学加工性能和安全性能,又具有传统液态电解质较高的室温离子电导率。但凝胶聚合物电解质由于室温离子电导率低、力学强度较差的缺点限制了其在锂离子电池上的应用。结合目前研究的最新进展,文中针对几种常用凝胶聚合物电解质体系聚氧化乙烯、聚丙烯腈、聚甲基丙烯酸甲酯、聚偏氟乙烯-六氟丙烯和聚乙烯醇缩醛进行了综述,对其制备方法以及通过聚合物调控、加入无机填料和复合离子液体进行改性处理做了较全面的介绍,并探讨了凝胶聚合物电解质的应用前景。%Gel polymer electrolytes (GPEs) possess both good processibility and safety performance of solid polymer electrolyte and a high conductivity of liquid electrolyte. However, the low conductivity at room temperature and poor mechanical strength restrict their applications in lithium-ion batteries. In this paper, the up-to-date research progress of some attractive gel polymer electrolytes have been reviewed, including poly(ethylene oxide) (PEO), poly (acrylonitrile) (PAN), poly ( methyl methacrylate) (PMMA), poly ( vinylidene fluoride-hexafluoro propylene) (PVdF-HFP) and poly(vinyl acetal) s (PVAc). Additionally, their preparation methods have been summarized. And the improvements of their properties are focused on, by modifying polymer structure, reinforcing with inorganic fillers and blending with ionic liquids. Finally, the prospects of their application in lithium-ion batteries are also discussed here.

  4. Energy Harvesting Cycles of Dielectric ElectroActive Polymer Generators

    DEFF Research Database (Denmark)

    Dimopoulos, Emmanouil; Trintis, Ionut; Munk-Nielsen, Stig

    2012-01-01

    Energy harvesting via Dielectric ElectroActive Polymer (DEAP) generators has attracted much of the scientific interest over the past few years, mainly due to the advantages that these smart materials offer against competing technologies, as electromagnetic generators and piezoelectrics....... Their higher energy density, superior low-speed performance, light-weighted nature as well as their shapely structure have rendered DEAPs candidate solutions for various actuation and energy harvesting applications. In this paper, a thoroughly analysis of all energy harvesting operational cycles of a DEAP...

  5. Energy harvesting with Di-Electro Active Polymers

    DEFF Research Database (Denmark)

    Due, Jens; Munk-Nielsen, Stig; Nielsen, Rasmus Ørndrup

    2010-01-01

    This article presents a way of using Di-Electro Active Polymers (D-EAPs) for harvesting mechanical energy sources. The article describes the basics of energy harvesting with D-EAPs, and an electrical model of a D-EAP is suggested. This leads to a converter design which is able to extract...... the electrical energy harvested by the D-EAP. This converter is simulated and realized. Through experimental results both the model of the DEAP and the converter are verified. It is found that it is possible to harvest energy with a D-EAP and build a converter that can extract the harvested energy....

  6. In vitro antimicrobial activity of Zingiber cassumunar (Plai) oil and a 5% Plai oil gel.

    Science.gov (United States)

    Pithayanukul, P; Tubprasert, J; Wuthi-Udomlert, M

    2007-02-01

    The essential oil of Zingiber cassumunar (Plai oil) exhibits antimicrobial activity against a wide range of Gram-positive and Gram-negative bacteria, dermatophytes and yeasts. Dermatophytes were found to be the most susceptible microorganisms followed by yeasts, whereas bacteria were the least susceptible. The mean diameter of the inhibition zone determined by the disc diffusion screening method increased with increasing Plai oil concentration between 6.25 and 50 vol %. The minimum bactericidal concentration (MBC) determined by the broth macrodilution method ranged from 0.62 to 2.5 vol % for Plai oil and from 52 to 79 mg/mL for the 5 wt % Plai oil gel, whereas the minimum fungicidal concentration (MFC) ranged from 0.31 to 1.25 vol % for Plai oil and from 13.8 to 39.5 mg/mL for the 5% Plai oil gel. Copyright (c) 2006 John Wiley & Sons, Ltd.

  7. Preparation, characterization and photocatalytic activity of manganese doped TiO(2) immobilized on silica gel.

    Science.gov (United States)

    Xu, Yuehua; Lei, Bo; Guo, Laiqiu; Zhou, Wuyi; Liu, Youqin

    2008-12-15

    A series of Mn-TiO(2)/SiO(2) (silica gel loaded with manganese doped TiO(2)) photocatalysts have been prepared by sol-gel method, and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Photocatalytic activities were enhanced in photocatalytic degradation of methyl orange over Mn-TiO(2)/SiO(2). XPS analysis shows that a Ti-O-Si or Ti-O-Mn bond is formed on the surface of photocatalyst. Mn is doped as a mixture of Mn(2+) and Mn(3+) on the surface of 1.0mol% Mn-TiO(2)/SiO(2). Mn(3+) appears to trap electrons and prohibit the electron-hole recombination. The electrons trapped in Mn(3+) site are subsequently transferred to the adsorbed O(2). As a result, the combination of the electron-hole pair was reduced.

  8. Improved Mobility Control for Carbon Dioxide (CO{sub 2}) Enhanced Oil Recovery Using Silica-Polymer-Initiator (SPI) Gels

    Energy Technology Data Exchange (ETDEWEB)

    Oglesby, Kenneth

    2014-01-31

    SPI gels are multi-component silicate based gels for improving (areal and vertical) conformance in oilfield enhanced recovery operations, including water-floods and carbon dioxide (CO{sub 2}) floods, as well as other applications. SPI mixtures are like-water when pumped, but form light up to very thick, paste-like gels in contact with CO{sub 2}. When formed they are 3 to 10 times stronger than any gelled polyacrylamide gel now available, however, they are not as strong as cement or epoxy, allowing them to be washed / jetted out of the wellbore without drilling. This DOE funded project allowed 8 SPI field treatments to be performed in 6 wells (5 injection wells and 1 production well) in 2 different fields with different operators, in 2 different basins (Gulf Coast and Permian) and in 2 different rock types (sandstone and dolomite). Field A was in a central Mississippi sandstone that injected CO{sub 2} as an immiscible process. Field B was in the west Texas San Andres dolomite formation with a mature water-alternating-gas miscible CO{sub 2} flood. Field A treatments are now over 1 year old while Field B treatments have only 4 months data available under variable WAG conditions. Both fields had other operational events and well work occurring before/ during / after the treatments making definitive evaluation difficult. Laboratory static beaker and dynamic sand pack tests were performed with Ottawa sand and both fields’ core material, brines and crude oils to improve SPI chemistry, optimize SPI formulations, ensure SPI mix compatibility with field rocks and fluids, optimize SPI treatment field treatment volumes and methods, and ensure that strong gels set in the reservoir. Field quality control procedures were designed and utilized. Pre-treatment well (surface) injectivities ranged from 0.39 to 7.9 MMCF/psi. The SPI treatment volumes ranged from 20.7 cubic meters (m{sup 3}, 5460 gallons/ 130 bbls) to 691 m{sup 3} (182,658 gallons/ 4349 bbls). Various size and types

  9. Performance of electrical double layer capacitors fabricated with gel polymer electrolytes containing Li{sup +} and K{sup +}-salts: A comparison

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Manoj K., E-mail: mmanoj.ssi@gmail.com; Hashmi, S. A. [Department of Physics & Astrophysics, University of Delhi, Delhi-110007 (India)

    2015-06-24

    The comparative performance of the solid-state electrical double layer capacitors (EDLCs) based on the multiwalled carbon nanotube (MWCNT) electrodes and poly (vinaylidinefluoride-co-hexafluoropropyline) (PVdF-HFP) based gel polymer electrolytes (GPEs) containing potassium and lithium salts have been studied. The room temperature ionic conductivity of the GPEs have been found to be ∼3.8×10{sup −3} and 5.9×10{sup −3} S cm{sup −1} for lithium and potassium based systems. The performance of EDLC cells studied by impedance spectroscopy, cyclic voltammetry and constant current charge-discharge techniques, indicate that the EDLC with potassium salt containing GPE shows excellent performance almost equivalent to the EDLC with Li-salt-based GPE.

  10. Characterization of TiO{sub 2}-Al{sub 2}O{sub 3} composite fibers formed by electrospinning a sol-gel and polymer mixture

    Energy Technology Data Exchange (ETDEWEB)

    Lotus, A.F. [Department of Chemical and Biomolecular Engineering, University of Akron, 185 E Mill Street, Akron, OH 44325 (United States); Feaver, R.K. [Physics Department, John Carroll University, University Heights, OH 44118 (United States); Britton, L.A. [Department of Chemistry, University of Akron, Akron, OH 44325 (United States); Bender, E.T. [Department of Medical Physics, University of Wisconsin-Madison, Madison, WI 53705 (United States); Perhay, D.A. [Physics Department, John Carroll University, University Heights, OH 44118 (United States); Stojilovic, N. [Department of Physics and Astronomy, University of Wisconsin Oshkosh, Oshkosh, WI 54901 (United States); Ramsier, R.D. [Department of Chemistry, University of Akron, Akron, OH 44325 (United States); Department of Physics, University of Akron, Akron, OH 44325 (United States); Office of the Provost, University of Akron, Akron, OH 44325 (United States); Chase, G.G., E-mail: gchase@uakron.ed [Department of Chemical and Biomolecular Engineering, University of Akron, 185 E Mill Street, Akron, OH 44325 (United States)

    2010-02-25

    Composite fibers of TiO{sub 2}-Al{sub 2}O{sub 3} were prepared by electrospinning a sol-gel and polymer mixture to form template polymeric fibers followed by calcination. The resulting fibers were characterized using thermogravimetric analysis (TGA), X-ray diffraction (XRD), diffuse reflectance ultraviolet-visible (UV-vis) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray energy dispersive spectroscopy (XEDS), and X-ray photoelectron spectroscopy (XPS). Calcination at 973 K resulted in mixture of anatase (A) titania and gamma (gamma) alumina phases. We calculated a band gap energy of 3.3 eV and found the average diameter of the resulting fibers in the 150-400 nm range. Both XEDS and XPS reveal that fibers are predominantly made of titania.

  11. Poly(Capro-Lactone) Networks as Actively Moving Polymers

    Science.gov (United States)

    Meng, Yuan

    Shape-memory polymers (SMPs), as a subset of actively moving polymers, form an exciting class of materials that can store and recover elastic deformation energy upon application of an external stimulus. Although engineering of SMPs nowadays has lead to robust materials that can memorize multiple temporary shapes, and can be triggered by various stimuli such as heat, light, moisture, or applied magnetic fields, further commercialization of SMPs is still constrained by the material's incapability to store large elastic energy, as well as its inherent one-way shape-change nature. This thesis develops a series of model semi-crystalline shape-memory networks that exhibit ultra-high energy storage capacity, with accurately tunable triggering temperature; by introducing a second competing network, or reconfiguring the existing network under strained state, configurational chain bias can be effectively locked-in, and give rise to two-way shape-actuators that, in the absence of an external load, elongates upon cooling and reversibly contracts upon heating. We found that well-defined network architecture plays essential role on strain-induced crystallization and on the performance of cold-drawn shape-memory polymers. Model networks with uniform molecular weight between crosslinks, and specified functionality of each net-point, results in tougher, more elastic materials with a high degree of crystallinity and outstanding shape-memory properties. The thermal behavior of the model networks can be finely modified by introducing non-crystalline small molecule linkers that effectively frustrates the crystallization of the network strands. This resulted in shape-memory networks that are ultra-sensitive to heat, as deformed materials can be efficiently triggered to revert to its permanent state upon only exposure to body temperature. We also coupled the same reaction adopted to create the model network with conventional free-radical polymerization to prepare a dual-cure "double

  12. MO-F-CAMPUS-T-02: Dosimetric Accuracy of the CrystalBallâ„¢: New Reusable Radiochromic Polymer Gel Dosimeter for Patient QA in Proton Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Avery, S; Kraus, J; Lin, L; Kassaee, A [University of Pennsylvania, Philadelphia, PA (United States); Maryanski, M [MGS Research, Inc., Madison, CT (United States)

    2015-06-15

    Purpose: To evaluate the accuracy of monoexponential normalization in a new class of commercial, reusable, human-soft-tissue-equivalent, radiochromic polymer gel dosimeters for patient-specific QA in proton therapy. Methods: Eight formulations of the dosimeter (sealed in glass spheres of 166 mm OD), were exposed to a 150 MeV proton beam (5 cm x 5 cm square field, range 15 cm, modulation10 cm), with max dose ranging from 2.5 Gy to 20 Gy, depending on formulation. Exposed dosimeters were promptly placed in the commercial OCTOPUS™ laser CT scanner which was programmed to scan the central slice every 5 minutes for 20 hours (15 seconds per slice scan). This procedure was repeated several times. Reconstructed data were analyzed using the log-lin scale to determine the time range over which a monoexponential relaxation model could be applied. Next, a simple test plan was devised and delivered to each dosimeter. The OCTOPUS™ was programmed to rescan the central slice at the end of each volume scan, for signal relaxation reference. Monoexponential normalization was applied to sinograms before FBP reconstruction. Dose calibration was based on a volume-lookup table built within the central spherical volume of 12 cm diameter. 3D gamma and sigma passing rates were measured at 3%/3mm criteria down to 50% isodose. Results: Approximately monoexponential signal relaxation time ranges from 25 minutes to 3.5 hours, depending on formulation, followed by a slower-relaxation component. Noise in reconstructed OD/cm images is less than 0.5%. Dose calibration accuracy is better than 99%. Measured proton PDDs demonstrate absence of Bragg-peak quenching. Estimated number of useful cycles is at least 20, with a theoretical limit above 100. 3D gamma and sigma passing rates exceed 95%. Conclusion: Monoexponential normalization was found to yield adequate dosimetric accuracy in the new class of commercial radiochromic polymer gel dosimeters for patient QA in proton therapy.

  13. A hybrid enrichment process combining conjugated polymer extraction and silica gel adsorption for high purity semiconducting single-walled carbon nanotubes (SWCNT)

    Science.gov (United States)

    Ding, Jianfu; Li, Zhao; Lefebvre, Jacques; Cheng, Fuyong; Dunford, Jeffrey L.; Malenfant, Patrick R. L.; Humes, Jefford; Kroeger, Jens

    2015-09-01

    A novel purification process for the enrichment of sc-SWCNTs that combines selective conjugated polymer extraction (CPE) with selective adsorption using silica gel, termed hybrid-CPE (h-CPE), has been developed, providing a high purity sc-SWCNT material with a significant improvement in process efficiency and yield. Using the h-CPE protocol, a greater than 5 fold improvement in yield can be obtained compared to traditional CPE while obtaining sc-SWCNT with a purity >99.9% as assessed by absorption spectroscopy and Raman mapping. Thin film transistor devices using the h-CPE derived sc-SWCNTs as the semiconductor possess mobility values ranging from 10-30 cm2 V-1 s-1 and current ON/OFF ratio of 104-105 for channel lengths between 2.5 and 20 μm.A novel purification process for the enrichment of sc-SWCNTs that combines selective conjugated polymer extraction (CPE) with selective adsorption using silica gel, termed hybrid-CPE (h-CPE), has been developed, providing a high purity sc-SWCNT material with a significant improvement in process efficiency and yield. Using the h-CPE protocol, a greater than 5 fold improvement in yield can be obtained compared to traditional CPE while obtaining sc-SWCNT with a purity >99.9% as assessed by absorption spectroscopy and Raman mapping. Thin film transistor devices using the h-CPE derived sc-SWCNTs as the semiconductor possess mobility values ranging from 10-30 cm2 V-1 s-1 and current ON/OFF ratio of 104-105 for channel lengths between 2.5 and 20 μm. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04851f

  14. SU-E-T-102: Determination of Dose Distributions and Water-Equivalence of MAGIC-F Polymer Gel for 60Co and 192Ir Brachytherapy Sources

    Energy Technology Data Exchange (ETDEWEB)

    Quevedo, A; Nicolucci, P [University of Sao Paulo, Ribeirao Preto, SP (Brazil)

    2014-06-01

    Purpose: Analyse the water-equivalence of MAGIC-f polymer gel for {sup 60}Co and {sup 192}Ir clinical brachytherapy sources, through dose distributions simulated with PENELOPE Monte Carlo code. Methods: The real geometry of {sup 60} (BEBIG, modelo Co0.A86) and {sup 192}192Ir (Varian, model GammaMed Plus) clinical brachytherapy sources were modelled on PENELOPE Monte Carlo simulation code. The most probable emission lines of photons were used for both sources: 17 emission lines for {sup 192}Ir and 12 lines for {sup 60}. The dose distributions were obtained in a cubic water or gel homogeneous phantom (30 × 30 × 30 cm{sup 3}), with the source positioned in the middle of the phantom. In all cases the number of simulation showers remained constant at 10{sup 9} particles. A specific material for gel was constructed in PENELOPE using weight fraction components of MAGIC-f: wH = 0,1062, wC = 0,0751, wN = 0,0139, wO = 0,8021, wS = 2,58×10{sup −6} e wCu = 5,08 × 10{sup −6}. The voxel size in the dose distributions was 0.6 mm. Dose distribution maps on the longitudinal and radial direction through the centre of the source were used to analyse the water-equivalence of MAGIC-f. Results: For the {sup 60} source, the maximum diferences in relative doses obtained in the gel and water were 0,65% and 1,90%, for radial and longitudinal direction, respectively. For {sup 192}Ir, the maximum difereces in relative doses were 0,30% and 1,05%, for radial and longitudinal direction, respectively. The materials equivalence can also be verified through the effective atomic number and density of each material: Zef-MAGIC-f = 7,07 e .MAGIC-f = 1,060 g/cm{sup 3} and Zef-water = 7,22. Conclusion: The results showed that MAGIC-f is water equivalent, consequently being suitable to simulate soft tissue, for Cobalt and Iridium energies. Hence, gel can be used as a dosimeter in clinical applications. Further investigation to its use in a clinical protocol is needed.

  15. An application of optical coherence tomography and a smart polymer gel to construct an enzyme-free sugar sensor

    Science.gov (United States)

    Ouiganon, Sirirat; Thammakhet, Chongdee; Thavarungkul, Panote; Kanatharana, Proespichaya; Buranachai, Chittanon

    2016-06-01

    This work reports a novel enzyme-free sugar sensor development based on optical coherence tomography (OCT) and a 3-acrylamidophenylboronic acid-acrylamide copolymer gel that swells when it binds sugar molecules. Utilizing OCT to measure the gel swelling in the presence of glucose and fructose, selected as model targets, the sensor provided a linear range of 2.5-20.0 mM for glucose and 0.01-0.20 mM for fructose detections with a good sensitivity for both sugars under optimal conditions. With some further improvements, the sensor could be used in harsh conditions that are not suitable for enzyme-based sugar sensors and for highly visible light-absorbing solutions.

  16. DMA and Conductivity Studies in PVA:NH4SCN:DMSO:MWNT Nanocomposite Polymer Dried Gel Electrolytes

    Directory of Open Access Journals (Sweden)

    S. L. Agrawal

    2015-01-01

    Full Text Available This paper deals with findings on dynamic mechanical analysis (DMA and ion-conduction behavior of MWNTs (multiwall carbon nanotubes doped PVA:NH4SCN:DMSO dried gel electrolyte system prepared for four filler concentrations (2, 4, 6 & 8 wt% by solution cast technique. XRD measurements reveal enhancement in amorphous behavior of composite gel electrolyte upon incorporation of filler particles. Better mechanical stability is noticed in the composite system upon dispersal of MWNT along with presence of dynamic Tg during DMA measurements. Enhancement in ionic conductivity has been noticed with an optimum value of 4.5 × 10−3 Scm−1 for 6 wt% MWNTs filled composite electrolyte. Composite system exhibits combination of Arrhenius and Vogel-Tammam-Fulcher (VTF behavior in temperature dependent conductivity study. The a.c. conductivity response seems to follow universal power law.

  17. All-solid-state supercapacitors with poly(3,4-ethylenedioxythiophene)-coated carbon fiber paper electrodes and ionic liquid gel polymer electrolyte

    Science.gov (United States)

    Pandey, G. P.; Rastogi, A. C.; Westgate, Charles R.

    2014-01-01

    All-solid-state thin supercapacitors have been fabricated using current pulse polymerized poly(3,4-ethylenedioxythiophene) (PEDOT) over carbon fiber paper and ionic liquid based gel polymer electrolyte. The PEDOT-coated carbon paper electrodes were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) which confirm the porous morphology of PEDOT at the nanoscale and a high degree of ClO4- dopant ion conjugation. The performance characteristics of the supercapacitor cells have been evaluated by ac impedance spectroscopy, cyclic voltammetry and galvanostatic charge-discharge techniques. The PEDOT electrode shows specific capacitance of ∼154.5 F g-1, which correspond to the cell area-normalized capacitance of 85 mF cm-2. The maximum specific energy and specific power of the solid-state supercapacitor cell, calculated from charge-discharge characteristics, are 6.5 Wh kg-1 and 11.3 kW kg-1, respectively. The solid-state supercapacitor shows good cycle durability and time stability. The thin, lightweight, gel electrolyte based supercapacitor shows considerable potential for low-cost, high-performance energy storage applications.

  18. Properties of collagen gels cross-linked by N-hydroxysuccinimide activated adipic acid deriviate.

    Science.gov (United States)

    Duan, Lian; Liu, Wentao; Tian, Zhenhua; Li, Conghu; Li, Guoying

    2014-08-01

    In order to improve the properties of collagen gel, N-hydroxysuccinimide activated adipic acid derivative (NHS-AA) was introduced into the formation of collagen fibrils. NHS-AA with different [NHS-AA]/[NH2] ratios (0.1-1.5, calculated by [ester group] of NHS-AA and [NH2] of lysine and hydroxylysine residues of collagen) was added after, simultaneously with or before the formation of collagen fibrils (abbreviated CAF, CSF and CBF, respectively) to obtain different collagen gels. With the same dose of NHS-AA, the cross-linking degree for CAF was lower than those for CSF and CBF. The formation of collagen fibrils was restrained by NHS-AA for CSF and CBF while that for CAF was unaffected. When the dose of NHS-AA increased from 0.1 to 1.5, the water contents of CSF and CBF increased while that of CAF had no obvious change. With lower dose of NHS-AA (0.1), CAF possessed higher value of G' (87.3Pa) and the best thermal stability (47.6°C). As the ratio of [NHS-AA]/[NH2] increased to 1.5, CSF had the maximum value of G' (288.8Pa) and CAF had the best thermal stability (52.9°C). These results showed collagen gels with different properties could be prepared by adding NHS-AA with different adding sequence and dose.

  19. Rapid Detection of Glycogen Synthase Kinase-3 Activity in Mouse Sperm Using Fluorescent Gel Shift Electrophoresis

    Directory of Open Access Journals (Sweden)

    Hoseok Choi

    2016-04-01

    Full Text Available Assaying the glycogen synthase kinase-3 (GSK3 activity in sperm is of great importance because it is closely implicated in sperm motility and male infertility. While a number of studies on GSK3 activity have relied on labor-intensive immunoblotting to identify phosphorylated GSK3, here we report the simple and rapid detection of GSK3 activity in mouse sperm using conventional agarose gel electrophoresis and a fluorescent peptide substrate. When a dye-tethered and prephosphorylated (primed peptide substrate for GSK3 was employed, a distinct mobility shift in the fluorescent bands on the agarose was observed by GSK3-induced phosphorylation of the primed peptides. The GSK3 activity in mouse testes and sperm were quantifiable by gel shift assay with low sample consumption and were significantly correlated with the expression levels of GSK3 and p-GSK3. We suggest that our assay can be used for reliable and rapid detection of GSK3 activity in cells and tissue extracts.

  20. Wood-Based Nanocomposite Derived by in Situ Formation of Organic-Inorganic Hybrid Polymer within Wood via a Sol-Gel Method.

    Science.gov (United States)

    Dong, Xiaoying; Zhuo, Xiao; Wei, Jie; Zhang, Gang; Li, Yongfeng

    2017-03-15

    Solid wood materials and wood-plastic composites as two kinds of lightweight materials are attracting great interest from academia and industry due to their green and recycling nature. However, the relatively lower specific strength limits their wider applications. In particular, solid wood is vulnerable to moisture and decay fungi in nature, resulting in its poor durability for effectively long-term utilization. Inspired from the porous structure of wood, we propose a new design to build a wood-based nanocomposite with higher specific strength and satisfactory durability by in situ generation of organic-inorganic hybrid polymer within wood via a sol-gel method. The derived composite has 50-1200% improvement of impact toughness, 56-192% improvement of tensile strength, and 110-291% improvement of flexural strength over those of typical wood-plastic composites, respectively; and even 34% improvement of specific tensile strength than that of 36A steel; 208% enhancement of hardness; and 156% enhancement of compression strength than those of compared solid wood, respectively; as well as significantly improved dimensional stability and decay resistance over those of untreated natural wood. Such materials could be potentially utilized as lightweight and high-strength materials for applications in construction and automotive industries. This method could be extended to constitute other inorganic nanomaterials for novel organic-inorganic hybrid polymer within wood.

  1. Antibacterial Activity of Two Chemomechanical Caries Removal Gels on Carious Dentin of Primary Teeth: An in vitro Study.

    Science.gov (United States)

    Gulzar, Shabnam; Arora, Ruchi; Shah, Altaf H; Bhardwaj, Bhupendra; Abusalim, Ghadah; Khalil, Hesham S; Wyne, Amjad H

    2016-12-01

    Chemomechanical caries removal (CMCR) is an effective method of caries removal especially for primary teeth as they cause less discomfort when compared with conventional caries removal. The most significant thing about caries removal is the elimination of cariogenic bacteria. This study compares the antibacterial activity of two CMCR gels. A total of 40 primary molar teeth with carious dentin were split along the long axis in a laboratory. Total viable count (TVC) was taken for the teeth before splitting as a measure of colony-forming units per milliliter (CFU/mL). Each half was treated with either Carisolv or Carie-Care CMCR gels. Clean dentin samples were evaluated for Streptococcus mutans (SM) and Lactobacillus acidophilus (LB) after removal of carious tissue using the caries removal gels using serial dilutions and incubating on specific agar plates. The results showed significant reduction in mean TVC after use of both the CMCR gels. Both gels reduced the CFU/mL of SM and LB to a significant level (p carious primary dentin. Both CMCR gels had a similar antibacterial activity on the carious dentin of primary teeth. The CMCR gels tested have a significant antibacterial activity and can be effectively used for elimination of caries-causing bacteria in primary teeth.

  2. Electrocatalytic properties and stability of titanium anodes activated by the inorganic sol–gel procedure

    Directory of Open Access Journals (Sweden)

    VLADIMIR V. PANIC

    2008-10-01

    Full Text Available The properties of activated titanium anodes, RuO2–TiO2/Ti and RuO2–TiO2–IrO2/Ti, prepared from oxide sols by the sol–gel procedure, are reviewed. RuO2 and TiO2 sols were synthesized by forced hydrolysis of the corresponding chlorides in acid medium. The morphology of the prepared sols was investigated by transmission electron microscopy. The chemical composition of the RuO2 sol was determined by X-ray diffraction and thermogravimetric analysis. The loss of electrocatalytic activity of a RuO2–TiO2/Ti anode during an accelerated stability test was investigated by examination of the changes in the electrochemical characteristics in the potential region of the chlorine and oxygen evolution reaction, as well as on the open circuit potential. These electrochemical characteristics were investigated by cyclic voltammetry, electrochemical impedance spectroscopy and polarization measurements. The changes in electrochemical characteristics of the anode prepared by the sol–gel procedure were compared to the changes registered for an anode prepared by the traditional thermal decomposition of metal chlorides. The comparison indicated that the main cause for the activity loss of the sol–gel prepared anode was the electrochemical dissolution of RuO2, while in the case of thermally prepared anode the loss was mainly caused by the formation of an insulating TiO2 layer in the coating/Ti substrate interphase. The results of an accelerated stability test on RuO2–TiO2/Ti and RuO2–TiO2–IrO2/Ti anodes showed that the ternary coating is considerably more stable than the binary one, which is the consequence of the greater stability of IrO2 in comparison to RuO2.

  3. Achieving synchronization with active hybrid materials: Coupling self-oscillating gels and piezoelectric films.

    Science.gov (United States)

    Yashin, Victor V; Levitan, Steven P; Balazs, Anna C

    2015-06-24

    Lightweight, deformable materials that can sense and respond to human touch and motion can be the basis of future wearable computers, where the material itself will be capable of performing computations. To facilitate the creation of "materials that compute", we draw from two emerging modalities for computation: chemical computing, which relies on reaction-diffusion mechanisms to perform operations, and oscillatory computing, which performs pattern recognition through synchronization of coupled oscillators. Chemical computing systems, however, suffer from the fact that the reacting species are coupled only locally; the coupling is limited by diffusion as the chemical waves propagate throughout the system. Additionally, oscillatory computing systems have not utilized a potentially wearable material. To address both these limitations, we develop the first model for coupling self-oscillating polymer gels to a piezoelectric (PZ) micro-electro-mechanical system (MEMS). The resulting transduction between chemo-mechanical and electrical energy creates signals that can be propagated quickly over long distances and thus, permits remote, non-diffusively coupled oscillators to communicate and synchronize. Moreover, the oscillators can be organized into arbitrary topologies because the electrical connections lift the limitations of diffusive coupling. Using our model, we predict the synchronization behavior that can be used for computational tasks, ultimately enabling "materials that compute".

  4. Photocatalytic Activity of Nanosized ZnWO4 Prepared by the Sol-gel Method

    Institute of Scientific and Technical Information of China (English)

    WU Yan; ZHANG Shi-cheng; ZHANG Li-wu; ZHU Yong-fa

    2007-01-01

    Nanosized ZnWO4 photocatalysts were successfully synthesized via the sol-gel process in a temperature range of 450-800 ℃. The grain size, crystal size, and crystallinity of ZnWO4 particles increased with the increase of calcination temperature and prolonging calcination time. The photocatalytic activity was measured for the degradation of an aqueous Rhodamine-B(RhB) solution and gaseous formaldehyde(FAD). With the increase of calcination temperature and time, the activities increased to a maximum and then decreased. ZnWO4 photocatalyst prepared at 550 ℃ for 10 h showed the highest activity, which is similar to the photocatalytic activity of P25TiO2 for the degradation of gaseous FAD. High crystallinity, large surface area, and good dispersion are responsible for the high photocatalytic performance of the prepared ZnWO4.

  5. Photocatalytic and antibacterial activity of ZnO powders prepared via sol-gel method

    Directory of Open Access Journals (Sweden)

    Weerachai Sangchay

    2016-02-01

    Full Text Available We report on synthesis of ZnO powders via sol-gel method. The prepared powders were calcined at the temperature of 300, 500 and 700°C for 1 h with the heating rate of 10°C/min. The microstructures of the fabricated powders were characterized by SEM and XRD techniques, and the results show that all samples were the agglomeration and spherical shape and reveal only the wurtzite phase. The photocatalytic activities of the powders were also tested via the degradation of methylene blue (MB solution under UV irradiation. Finally, antibacterial activity efficiency was evaluated by the inactivation of E. coli. It was observed that higher calcined at the temperature gives better photocatalytic and antibacterial activity. With the highest calcined at the temperature investigated in this experiment (T700 condition the powders show photocatalytic and antibacterial activities of 80.06 and 99.00%, respectively.

  6. Effect of Thiolated Polymers to Textural and Mucoadhesive Properties of Vaginal Gel Formulations Prepared with Polycarbophil and Chitosan

    OpenAIRE

    Cevher, Erdal; Sensoy, Demet; Taha, Mohamed A. M.; Araman, Ahmet

    2008-01-01

    The aim of this study was to design and evaluate of mucoadhesive gel formulations for the vaginal application of clomiphene citrate (CLM) for local treatment of human papilloma virus (HPV) infections. Chitosan (CHI) and polycarbophil (PC) were covalently modified using the thioglycolic acid and L-cysteine, respectively. The formation of thiol conjugates of chitosan (CHI-TG) and polycarbophil (PC-CYS) were confirmed by FT-IR analysis and PC-CYS and CHI-TG were found to have 148.42 ± 4.16 and 4...

  7. Thermoresponsive Gels

    Directory of Open Access Journals (Sweden)

    M. Joan Taylor

    2017-01-01

    Full Text Available Thermoresponsive gelling materials constructed from natural and synthetic polymers can be used to provide triggered action and therefore customised products such as drug delivery and regenerative medicine types as well as for other industries. Some materials give Arrhenius-type viscosity changes based on coil to globule transitions. Others produce more counterintuitive responses to temperature change because of agglomeration induced by enthalpic or entropic drivers. Extensive covalent crosslinking superimposes complexity of response and the upper and lower critical solution temperatures can translate to critical volume temperatures for these swellable but insoluble gels. Their structure and volume response confer advantages for actuation though they lack robustness. Dynamic covalent bonding has created an intermediate category where shape moulding and self-healing variants are useful for several platforms. Developing synthesis methodology—for example, Reversible Addition Fragmentation chain Transfer (RAFT and Atomic Transfer Radical Polymerisation (ATRP—provides an almost infinite range of materials that can be used for many of these gelling systems. For those that self-assemble into micelle systems that can gel, the upper and lower critical solution temperatures (UCST and LCST are analogous to those for simpler dispersible polymers. However, the tuned hydrophobic-hydrophilic balance plus the introduction of additional pH-sensitivity and, for instance, thermochromic response, open the potential for coupled mechanisms to create complex drug targeting effects at the cellular level.

  8. Quantitative structure-activity relationships for green algae growth inhibition by polymer particles.

    Science.gov (United States)

    Nolte, Tom M; Peijnenburg, Willie J G M; Hendriks, A Jan; van de Meent, Dik

    2017-03-19

    After use and disposal of chemical products, many types of polymer particles end up in the aquatic environment with potential toxic effects to primary producers like green algae. In this study, we have developed Quantitative Structure-Activity Relationships (QSARs) for a set of highly structural diverse polymers which are capable to estimate green algae growth inhibition (EC50). The model (N = 43, R(2) = 0.73, RMSE = 0.28) is a regression-based decision tree using one structural descriptor for each of three polymer classes separated based on charge. The QSAR is applicable to linear homo polymers as well as copolymers and does not require information on the size of the polymer particle or underlying core material. Highly branched polymers, non-nitrogen cationic polymers and polymeric surfactants are not included in the model and thus cannot be evaluated. The model works best for cationic and non-ionic polymers for which cellular adsorption, disruption of the cell wall and photosynthesis inhibition were the mechanisms of action. For anionic polymers, specific properties of the polymer and test characteristics need to be known for detailed assessment. The data and QSAR results for anionic polymers, when combined with molecular dynamics simulations indicated that nutrient depletion is likely the dominant mode of toxicity. Nutrient depletion in turn, is determined by the non-linear interplay between polymer charge density and backbone flexibility.

  9. Nonequilibrium structure and dynamics in a microscopic model of thin-film active gels

    Science.gov (United States)

    Head, D. A.; Briels, W. J.; Gompper, Gerhard

    2014-03-01

    In the presence of adenosine triphosphate, molecular motors generate active force dipoles that drive suspensions of protein filaments far from thermodynamic equilibrium, leading to exotic dynamics and pattern formation. Microscopic modeling can help to quantify the relationship between individual motors plus filaments to organization and dynamics on molecular and supramolecular length scales. Here, we present results of extensive numerical simulations of active gels where the motors and filaments are confined between two infinite parallel plates. Thermal fluctuations and excluded-volume interactions between filaments are included. A systematic variation of rates for motor motion, attachment, and detachment, including a differential detachment rate from filament ends, reveals a range of nonequilibrium behavior. Strong motor binding produces structured filament aggregates that we refer to as asters, bundles, or layers, whose stability depends on motor speed and differential end detachment. The gross features of the dependence of the observed structures on the motor rate and the filament concentration can be captured by a simple one-filament model. Loosely bound aggregates exhibit superdiffusive mass transport, where filament translocation scales with lag time with nonunique exponents that depend on motor kinetics. An empirical data collapse of filament speed as a function of motor speed and end detachment is found, suggesting a dimensional reduction of the relevant parameter space. We conclude by discussing the perspectives of microscopic modeling in the field of active gels.

  10. Molecularly imprinted polymer grafted on polysaccharide microsphere surface by the sol-gel process for protein recognition.

    Science.gov (United States)

    Li, Feng; Li, Jing; Zhang, Shusheng

    2008-02-15

    An interfacial organic-inorganic hybridization concept was applied to the preparation of a new spherical imprinted material for protein recognition. The functional biopolymer chitosan (CS), shaped as microsphere and high-density cross-linked, constituted of the polysaccharide core for surface imprinting. After the model template protein, bovine serum albumin, was covalently immobilized by forming imine bonds with the functional amine groups of CS, two kinds of organic siloxane (3-aminopropyltrimethoxysiloxane: APTMS, and tetraethoxysiloxane: TEOS) assembled and polymerized on the polysaccharide-protein surface via sol-gel process in aqueous solution at room temperature. After template removal, the protein-imprinted sol-gel surface exhibited a prevalent preference for the template protein in adsorption experiments, as compared with four contrastive proteins. Bioinformatics methods were also employed to investigate the imprinting process and the recognition effect. The influence of siloxane type, pH, siloxane/water ratio on template removal and recognition selectivity was assessed. Under optimized imprinting conditions, a large quantity of well-distributed pores was observed on the immobilized-template imprinted surface. The surface-imprinted adsorbent offered a fast kinetics for template re-adsorption and could be reused. Compared with the imprinted material prepared with free-template, material prepared with immobilized-template possessed higher adsorption capacity towards template protein. Easy preparation of the described imprinted material, high affinity and good reusability make this approach attractive and broadly applicable in biotechnology for down-stream processing and biosensor.

  11. Pengaruh Natrium Hialuronat terhadap Penetrasi Kofein Sebagai Antiselulit dalam Sediaan Hidrogel, Hidroalkoholik Gel, dan Emulsi Gel

    Directory of Open Access Journals (Sweden)

    Joshita Djajadisastra

    2014-04-01

    Full Text Available Anticellulite topical gel preparation with caffeine as an active ingredient needs a penetration enhancer to reach subcutaneous layer. Sodium hyaluronate (NaHA, the sodium salt of hyaluronic acid, is a hydrophilic polysaccharide derivative polymer. It has an ability to enhance percutaneous penetration by loosening the dense of the compact substance of stratum corneum. The aim of this research was to observe the effects of NaHA on caffeine penetration as an anticellulite active agent in three types of gel preparation: hydrogel, hydroalcoholic gel, and gel emulsion. Each gel type contained caffeine 1,5% and was varied into three formulas. Formula 1 contained HPMC 2% as gel basis; formula 2 contained HPMC 2% and NaHA 0,5% as gel basis; formula 3 contained NaHA 2% as gel basis. Caffeine penetration properties were analyzed by Franz diffusion cell in vitro test using rat skin as membrane. Percent caffeine penetration of hydrogel formula 1, 2, 3 were 9,41 ± 0,01%; 11,74 ± 0,13%; 16,32 ± 0,03%, respectively. Percent caffeine penetration of hydroalcoholic gel formula 1, 2, 3 were 19,54 ± 0,02%; 22,99 ± 0,23%; 7,42 ± 0,08%, respectively. Percent caffeine penetration of gel emulsion formula 1, 2, 3 were 10,47 ± 0,19%; 13,41 ± 0,12%; 18,42 ± 0,06%, respectively. The result showed that NaHA enhanced the caffeine percutaneous penetration properties in various gel preparations, except hidroalkoholic gel formula 3.

  12. CONFORMANCE IMPROVEMENT USING GELS

    Energy Technology Data Exchange (ETDEWEB)

    Randall S. Seright

    2003-09-01

    flow capacity of fractures (with widths from 1 to 4 mm) during brine and oil flow after placement. Regardless of gel age before placement, very little gel washed out from the fractures during brine or oil flow. However, increased brine or oil flow rate and cyclic injection of oil and water significantly decreased the level of permeability reduction. A particular need exists for gels that can plug large apertures (e.g., wide fractures and vugs). Improved mechanical strength and stability were demonstrated (in 1- to 4-mm-wide fractures) for a gel that contained a combination of high- and low-molecular weight polymers. This gel reduced the flow capacity of 2- and 4-mm-wide fractures by 260,000. In a 1-mm-wide fracture, it withstood 26 psi/ft without allowing any brine flow through the fracture. Cr(III)-acetate-HPAM gels exhibited disproportionate permeability reduction in fractures. The effect was most pronounced when the gel was placed as gelant or partially formed gels. The effect occurred to a modest extent with concentrated gels and with gels that were ''fully formed'' when placed. The effect was not evident in tubes. We explored swelling polymers for plugging fractures. Polymer suspensions were quickly prepared and injected. In concept, the partially dissolved polymer would lodge and swell to plug the fracture. For three types of swelling polymers, behavior was promising. However, additional development is needed before their performance will be superior to that of conventional gels.

  13. Fabricating porous materials using interpenetrating inorganic-organic composite gels

    Science.gov (United States)

    Seo, Dong-Kyun; Volosin, Alex

    2016-06-14

    Porous materials are fabricated using interpenetrating inorganic-organic composite gels. A mixture or precursor solution including an inorganic gel precursor, an organic polymer gel precursor, and a solvent is treated to form an inorganic wet gel including the organic polymer gel precursor and the solvent. The inorganic wet gel is then treated to form a composite wet gel including an organic polymer network in the body of the inorganic wet gel, producing an interpenetrating inorganic-organic composite gel. The composite wet gel is dried to form a composite material including the organic polymer network and an inorganic network component. The composite material can be treated further to form a porous composite material, a porous polymer or polymer composite, a porous metal oxide, and other porous materials.

  14. Detection of enzymes active on various beta-1,3-glucans after denaturing polyacrylamide gel electrophoresis.

    Science.gov (United States)

    Trudel, J; Grenier, J; Asselin, A

    1998-07-01

    Enzymes were assayed for glucanase activity after denaturing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in gels containing beta-1,3-glucans embedded as substrate. Lentinan, curdlan, paramylon, baker's yeast alkali-insoluble glucan, baker's yeast alkali-soluble glucan and carboxymethyl (CM)-pachyman were compared to oligomeric laminarin, which is the usual substrate for assaying beta-1,3-glucanase activities. Detecting enzyme activities by aniline blue fluorescent staining was also compared with the staining of released reducing sugars by 2,3,5-triphenyltetrazolium chloride (TTC). For the nonreduced proteins, the Driselase extract exhibited one major band at 32.5 kDa and one less intense band at 23 kDa for most substrates with the two detection procedures. No Lyticase enzyme was detected in either detection procedures for all tested substrates. For barley enzymes, no activity was revealed after aniline blue staining while one undescribed 19 kDa glucanase activity was best shown after TTC staining with curdlan, paramylon and CM-pachyman as substrates. In the case of reduced proteins, the Lyticase extract yielded three bands (33, 36 and 46 kDa) on several substrates with both detection procedures. This was the same for the barley leaf extract (32, 36 and 39 kDa). The Driselase extract showed one 42 kDa band. Many enzymes active on beta-1,3-glucans are thus best revealed when proteins are denatured and reduced and when protein renaturation after SDS-PAGE involves a pH 8.0 treatment and the inclusion of 1 mM cysteine in buffers. However, some enzymes are only detected when proteins are denatured without reduction. Finally, the use of various polymeric beta-1,3-glucan substrates different from oligomeric laminarin is necessary to detect new types of enzymes such as the 19 kDa barley glucanase.

  15. Sol-gel prepared active ternary oxide coating on titanium in cathodic protection

    Directory of Open Access Journals (Sweden)

    VLADIMIR V. PANIC

    2007-12-01

    Full Text Available The characteristics of a ternary oxide coating, on titanium, which consisted of TiO2, RuO2 and IrO2 in the molar ratio 0.6:0.3:0.1, calculated on the metal atom, were investigated for potential application for cathodic protection in a seawater environment. The oxide coatings on titanium were prepared by the sol gel procedure from a mixture of inorganic oxide sols, which were obtained by forced hydrolysis of metal chlorides. The morphology of the coating was examined by scanning electron microscopy. The electrochemical properties of activated titanium anodes were investigated by cyclic voltammetry and polarization measurements in a H2SO4- and NaCl-containing electrolyte, as well as in seawater sampled on the Adriatic coast in Tivat, Montenegro. The anode stability during operation in seawater was investigated by the galvanostatic accelerated corrosion stability test. The morphology and electrochemical characteristics of the ternary coating are compared to that of a sol-gel-prepared binary Ti0.6Ru0.4O2 coating. The activity of the ternary coating was similar to that of the binary Ti0.6Ru0.4O2 coating in the investigated solutions. However, the corrosion stability in seawater is found to be considerably greater for the ternary coating.

  16. In vitro wound healing and cytotoxic activity of the gel and whole-leaf materials from selected aloe species.

    Science.gov (United States)

    Fox, Lizelle T; Mazumder, Anisha; Dwivedi, Anupma; Gerber, Minja; du Plessis, Jeanetta; Hamman, Josias H

    2017-03-22

    Aloe vera is one of the most important medicinal plants in the world with applications in the cosmetic industry and also in the tonic or health drink product market. Different parts of Aloe ferox and Aloe marlothii are used as traditional medicines for different applications. Although wound healing has been shown for certain aloe gel materials (e.g. A. vera ) previously, there are conflicting reports on this medicinal application of aloe leaf gel materials. The present study aimed at determining the wound healing properties of the gel and whole-leaf materials of Aloe vera, Aloe ferox and Aloe marlothii, as well as their cytotoxic effects on normal human keratinocyte cells (HaCaT). Nuclear magnetic resonance spectroscopy was used to chemically fingerprint the aloe gel and whole-leaf materials by identifying characteristic marker molecules of aloe gel and whole-leaf materials. An MTT assay was performed to determine the cytotoxicity of the various aloe whole-leaf and gel materials on HaCaT cells. Wound healing and in vitro cell migration were investigated with HaCaT cells by means of the CytoSelect™ assay kit. The in vitro wound healing assay suggested that all the aloe gel and whole-leaf materials examined, exhibited faster wound healing activity than the untreated control group. After 48h, all the aloe gel and whole-leaf materials almost completely caused full wound closure, displaying 98.07% (A. marlothii whole-leaf), 98.00% (A. vera gel), 97.20% (A. marlothii gel), 96.00% (A. vera whole-leaf), 94.00% (A. ferox gel) and 81.30% (A. ferox whole-leaf) wound closure, respectively. It was noteworthy that the gel materials of all the three aloe species exhibited significantly faster (pvera, A. ferox and A. marlothii have shown the ability to heal wounds at a faster rate and to a larger extent than untreated keratinocytes. The MTT assay results suggested that the gel and whole-leaf materials of all the selected Aloe species showed negligible toxicity towards the Ha

  17. 2010 POLYMER PHYSICS - JUNE 27 - JULY 2, 2010

    Energy Technology Data Exchange (ETDEWEB)

    Karen Winey

    2010-07-02

    The 2010 Gordon Research Conference on Polymer Physics will provide outstanding lectures and discussions in this critical field that impacts every industrial sector from electronics to transportation to medicine to textiles to energy generation and storage. Fundamental topics range from mechanical properties of soft gels to new understanding in polymer crystallization to energy conversion and transmission to simulating polymer dynamics at the nanoscale. This international conference will feature 22 invited lectures, wherein the opening 10 minutes are specifically designed for a general polymer physics audience. In addition, poster sessions and informal activities provide ample opportunity to discuss the latest advances in polymer physics. The technical content of the meeting will include new twists on traditional polymer physics topics, recent advances in previously underrepresented topics, and emerging technologies enabled by polymer physics. Here is a partially listing of targeted topics: (1) electrically-active and light-responsive polymers and polymer-based materials used in energy conversion and storage; (2) polymers with hierarchical structures including supramolecular assemblies, ion-containing polymers, and self-assembled block polymers; (3) mechanical and rheological properties of soft materials, such as hydrogels, and of heterogeneous materials, particularly microphase separated polymers and polymer nanocomposites; and (4) crystallization of polymers in dilute solutions, polymer melts, and miscible polymer blends.

  18. Improving the quality of reconstructed X-ray CT images of polymer gel dosimeters: zero-scan coupled with adaptive mean filtering.

    Science.gov (United States)

    Kakakhel, M B; Jirasek, A; Johnston, H; Kairn, T; Trapp, J V

    2017-02-06

    This study evaluated the feasibility of combining the 'zero-scan' (ZS) X-ray computed tomography (CT) based polymer gel dosimeter (PGD) readout with adaptive mean (AM) filtering for improving the signal to noise ratio (SNR), and to compare these results with available average scan (AS) X-ray CT readout techniques. NIPAM PGD were manufactured, irradiated with 6 MV photons, CT imaged and processed in Matlab. AM filter for two iterations, with 3 × 3 and 5 × 5 pixels (kernel size), was used in two scenarios (a) the CT images were subjected to AM filtering (pre-processing) and these were further employed to generate AS and ZS gel images, and (b) the AS and ZS images were first reconstructed from the CT images and then AM filtering was carried out (post-processing). SNR was computed in an ROI of 30 × 30 for different pre and post processing cases. Results showed that the ZS technique combined with AM filtering resulted in improved SNR. Using the previously-recommended 25 images for reconstruction the ZS pre-processed protocol can give an increase of 44% and 80% in SNR for 3 × 3 and 5 × 5 kernel sizes respectively. However, post processing using both techniques and filter sizes introduced blur and a reduction in the spatial resolution. Based on this work, it is possible to recommend that the ZS method may be combined with pre-processed AM filtering using appropriate kernel size, to produce a large increase in the SNR of the reconstructed PGD images.

  19. Non-equilibrium structure and dynamics in a microscopic model of thin film active gels

    CERN Document Server

    Head, D A; Gompper, G

    2013-01-01

    In the presence of ATP, molecular motors generate active force dipoles that drive suspensions of protein filaments far from thermodynamic equilibrium, leading to exotic dynamics and pattern formation. Microscopic modelling can help to quantify the relationship between individual motors plus filaments to the large-wavelength properties represented by "hydrodynamic" models. Here we present results of extensive numerical simulations of active gels where the motors and filaments are confined between two infinite parallel plates. Thermal fluctuations and excluded-volume interactions between filaments are included. A systematic variation of rates for motor motion, attachment and detachment, including a differential detachment rate from filament ends, reveals a range of non-equilibrium behaviour. Strong motor binding produces structured filament aggregates that we refer to as asters, bundles or layers, whose stability depends on motor speed and differential end-detachment. The gross features of the dependence of the...

  20. Microbicidal activity of TiO2 nanoparticles synthesised by sol-gel method.

    Science.gov (United States)

    Priyanka, Karathan Parakkandi; Sukirtha, Thiruvangium Henry; Balakrishna, Kagalagodu Manjunthiah; Varghese, Thomas

    2016-04-01

    In this study, the authors investigated antimicrobial activity of TiO2 nanoparticles (NPs) synthesised by sol-gel method. As synthesised TiO2 NPs were characterised by X-ray diffraction, scanning electron microscopy and ultraviolet-visible absorption spectroscopy. The antimicrobial activity of calcined TiO2 nanoparticle samples was examined in day light on Gram positive bacteria (Staphylococcus aureus, Streptococcus pneumonia and Bacillus subtilis), Gram negative bacteria (Proteus vulgaris, Pseudomonas aeruginosa and Escherichia coli) and fungal test pathogen Candida albicans. The synthesised TiO2 NPs were found to be effective in visible light against Streptococcus pneumonia, Staphylococcus aureus, Proteus vulgaris, Pseudomonas aeruginosa and Candida albicans.

  1. Performance improvement of gel- and solid-state dye-sensitized solar cells by utilization the blending effect of poly (vinylidene fluoride-co-hexafluropropylene) and poly (acrylonitrile-co-vinyl acetate) co-polymers

    Science.gov (United States)

    Venkatesan, Shanmugam; Obadja, Nesia; Chang, Ting-Wei; Chen, Li-Tung; Lee, Yuh-Lang

    2014-12-01

    Poly (vinylidene fluoride-co-hexafluropropylene) (PVDF-HFP) and poly (acrylonitrile-co-vinyl acetate) (PAN-VA) are used as gelator to prepare gel- and solid-state polymer electrolytes for dye sensitized solar cells (DSSCs) applications. The electrolytes prepared using PVDF-HFP have higher conductivities than those prepared using PAN-VA. In blended polymers, the conductivities of the electrolytes increase with increasing composition of PVDF-HFP; at 75% PVDF-HFP, conductivity of the blended polymer surpassed that of pure polymers. It is also found that the viscosity of the electrolyte prepared by PAN-VA (1.2 kPaS) is much lower than that by PVDF-HFP (11 kPaS). Therefore, increasing PAN-VA composition can decrease the viscosity of the electrolyte, improving the penetration of electrolytes in the TiO2 matrix. By controlling the ratio of PVDF-HFP/PAN-VA, the conductivity and viscosity of the electrolyte can be regulated and an optimal ratio based on the conversion efficiency of the gel- and solid state DSSCs is obtained at the ratio of 3/1. The highest efficiency achieved by the gel- and solid-state cells using the blending polymers are 6.3% and 4.88%, respectively, which are higher than those prepared using pure polymers (5.53% and 4.56%, respectively). The introduction of TiO2 fillers to the solid electrolyte can further increase the cell efficiency to 5.34%.

  2. 聚合物锂离子蓄电池用凝胶聚合物电解质%Gel polymeric electrolytes for polymer lithium-ion battery

    Institute of Scientific and Technical Information of China (English)

    汪国杰; 周震涛; 潘慧铭

    2001-01-01

    Polymer and plasticizer were two main components of gel polymeric electrolyte(GPE)for polymer lithi-um-ion battery, and the components structure and properties of GPE were introduced in details. Attention wasdevoted to reviewing the structure of components, interactions among them and how these factors affected the properties of GPE. Three methods for improving mechanical properties of GPE were reviewed-cross-linking, adding filler and using structure with two phases. Finally, introduced the main properties, current development and tendency of plastic Li-ion battery composed of GPE.%较详细地介绍了聚合物锂离子蓄电池用凝胶聚合物电解质的两种主要组成:聚合物和增塑剂,着重阐述了其各组分的结构和组分间相互作用对其性能的影响。综述了凝胶聚合物电解质的几个主要性能--离子传递性能,电化学稳定性,热稳定性和力学性能等,以及影响其有关性能的结构因素。还详述了改善凝胶聚合物电解质力学性能的三种方法:交联,添加填料和采用两相结构。最后介绍了由其制备的聚合物锂离子电池的性能、特点、研制现状和前景展望。

  3. Efficiency enhancement in dye sensitized solar cells using gel polymer electrolytes based on a tetrahexylammonium iodide and MgI2 binary iodide system.

    Science.gov (United States)

    Bandara, T M W J; Dissanayake, M A K L; Jayasundara, W J M J S R; Albinsson, I; Mellander, B-E

    2012-06-28

    Quasi-solid-state dye-sensitized solar cells have drawn the attention of scientists and technologists as a potential candidate to supplement future energy needs. The conduction of iodide ions in quasi-solid-state polymer electrolytes and the performance of dye sensitized solar cells containing such electrolytes can be enhanced by incorporating iodides having appropriate cations. Gel-type electrolytes, based on PAN host polymers and mixture of salts tetrahexylammonium iodide (Hex4N(+)I(-)) and MgI2, were prepared by incorporating ethylene carbonate and propylene carbonate as plasticizers. The salt composition in the binary mixture was varied in order to optimize the performance of solar cells. The electrolyte containing 120% Hex4N(+)I(-) with respect to weight of PAN and without MgI2 showed the highest conductivity out of the compositions studied, 2.5 × 10(-3) S cm(-1) at 25 °C, and a glass transition at -102.4 °C. However, the electrolyte containing 100% Hex4N(+)I(-) and 20% MgI2 showed the best solar cell performance highlighting the influence of the cation on the performance of the cell. The predominantly ionic behaviour of the electrolytes was established from the dc polarization data and all the electrolytes exhibit iodide ion transport. Seven different solar cells were fabricated employing different electrolyte compositions. The best cell using the electrolyte with 100% Hex4N(+)I(-) and 20% MgI2 with respect to PAN weight showed 3.5% energy conversion efficiency and 8.6 mA cm(-2) short circuit current density.

  4. Antimicrobial activity of thin solid films of silver doped hydroxyapatite prepared by sol-gel method.

    Science.gov (United States)

    Iconaru, Simona Liliana; Chapon, Patrick; Le Coustumer, Philippe; Predoi, Daniela

    2014-01-01

    In this work, the preparation and characterization of silver doped hydroxyapatite thin films were reported and their antimicrobial activity was characterized. Silver doped hydroxyapatite (Ag:HAp) thin films coatings substrate was prepared on commercially pure Si disks by sol-gel method. The silver doped hydroxyapatite thin films were characterized by various techniques such as Scanning electron microscopy (SEM) with energy Dispersive X-ray attachment (X-EDS), Fourier transform infrared spectroscopy (FT-IR), and glow discharge optical emission spectroscopy (GDOES). These techniques have permitted the structural and chemical characterisation of the silver doped hydroxyapatite thin films. The antimicrobial effect of the Ag:HAp thin films on Escherichia coli and Staphylococcus aureus bacteria was then investigated. This is the first study on the antimicrobial effect of Ag:HAp thin films obtained by sol-gel method. The results of this study have shown that the Ag:HAp thin films with x(Ag) = 0.5 are effective against E. coli and S. aureus after 24 h.

  5. Antimicrobial Activity of Thin Solid Films of Silver Doped Hydroxyapatite Prepared by Sol-Gel Method

    Directory of Open Access Journals (Sweden)

    Simona Liliana Iconaru

    2014-01-01

    Full Text Available In this work, the preparation and characterization of silver doped hydroxyapatite thin films were reported and their antimicrobial activity was characterized. Silver doped hydroxyapatite (Ag:HAp thin films coatings substrate was prepared on commercially pure Si disks by sol-gel method. The silver doped hydroxyapatite thin films were characterized by various techniques such as Scanning electron microscopy (SEM with energy Dispersive X-ray attachment (X-EDS, Fourier transform infrared spectroscopy (FT-IR, and glow discharge optical emission spectroscopy (GDOES. These techniques have permitted the structural and chemical characterisation of the silver doped hydroxyapatite thin films. The antimicrobial effect of the Ag:HAp thin films on Escherichia coli and Staphylococcus aureus bacteria was then investigated. This is the first study on the antimicrobial effect of Ag:HAp thin films obtained by sol-gel method. The results of this study have shown that the Ag:HAp thin films with xAg=0.5 are effective against E. coli and S. aureus after 24 h.

  6. Gel electrolytes and electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Fleischmann, Sven; Bunte, Christine; Mikhaylik, Yuriy V.; Viner, Veronika G.

    2017-09-05

    Gel electrolytes, especially gel electrolytes for electrochemical cells, are generally described. In some embodiments, the gel electrolyte layers comprise components a) to c). Component a) may be at least one layer of at least one polymer comprising polymerized units of: a1) at least one monomer containing an ethylenically unsaturated unit and an amido group and a2) at least one crosslinker. Component b) may be at least one conducting salt and component c) may be at least one solvent. Electrodes may comprise the components a), d) and e), wherein component a) may be at least one layer of at least one polymer as described herein. Component d) may be at least one electroactive layer and component e) may be at least one ceramic layer. Furthermore, electrochemical cells comprising component a) which may be at least one layer of at least one polymer as described herein, are also provided.

  7. Porous bodies of hydroxyapatite produced by a combination of the gel-casting and polymer sponge methods.

    Science.gov (United States)

    González Ocampo, Jazmín I; Escobar Sierra, Diana M; Ossa Orozco, Claudia P

    2016-03-01

    A combination of gel-casting and polymeric foam infiltration methods is used in this study to prepare porous bodies of hydroxyapatite (HA), to provide a better control over the microstructures of samples. These scaffolds were prepared by impregnating a body of porous polyurethane foam with slurry containing HA powder, and using a percentage of solids between 40% and 50% w/v, and three different types of monomers to provide a better performance. X-Ray Diffraction (XRD), and Fourier Transformed Infrared (FTIR) and Scanning Electron Microscopy (SEM) were employed to evaluate both the powder hydroxyapatite and the scaffolds obtained. In addition, porosity and interconnectivity measurements were taken in accordance with the international norm. Bioactivity was checked using immersion tests in Simulated Body Fluids (SBF). After the sintering process of the porous bodies, the XRD results showed peaks characteristic of a pure and crystalline HA (JCPDS 9-432) as a single phase. SEM images indicate open and interconnected pores inside the material, with pore sizes between 50 and 600 μm. Also, SEM images demonstrate the relatively good bioactivity of the HA scaffolds after immersion in SBF. All results for the porous HA bodies suggest that these materials have great potential for use in tissue engineering.

  8. Anti-biofilm activity of chitosan gels formulated with silver nanoparticles and their cytotoxic effect on human fibroblasts

    Energy Technology Data Exchange (ETDEWEB)

    Pérez-Díaz, M.; Alvarado-Gomez, E. [Facultad de Ciencias Quimicas, Universidad Autonoma de San Luis Potosi (Mexico); Magaña-Aquino, M. [Servicio de Epidemiologia del Hospital Central “Dr. Ignacio Morones Prieto”, San Luis Potosi (Mexico); Sánchez-Sánchez, R.; Velasquillo, C. [Laboratorio de Biotecnologia, Instituto Nacional de Rehabilitacion, Mexico, D.F. (Mexico); Gonzalez, C. [Facultad de Ciencias Quimicas, Universidad Autonoma de San Luis Potosi (Mexico); Ganem-Rondero, A. [Division de Estudios de Posgrado (Tecnologia Farmaceutica), Facultad de Estudios Superiores Cuautitlan, Universidad Nacional Autonoma de Mexico, Cuautitlan Izcalli, Estado de Mexico (Mexico); Martínez-Castañon, G.; Zavala-Alonso, N. [Doctorado en Ciencias Odontológicas Facultad de Estomatologia, UASLP (Mexico); Martinez-Gutierrez, F. [Facultad de Ciencias Quimicas, Universidad Autonoma de San Luis Potosi (Mexico)

    2016-03-01

    The development of multi-species biofilms in chronic wounds is a serious health problem that primarily generates strong resistance mechanisms to antimicrobial therapy. The use of silver nanoparticles (AgNPs) as a broad-spectrum antimicrobial agent has been studied previously. However, their cytotoxic effects limit its use within the medical area. The purpose of this study was to evaluate the anti-biofilm capacity of chitosan gel formulations loaded with AgNPs, using silver sulfadiazine (SSD) as a standard treatment, on strains of clinical isolates, as well as their cytotoxic effect on human primary fibroblasts. Multi-species biofilm of Staphylococcus aureus oxacillin resistant (MRSA) and Pseudomonas aeruginosa obtained from a patient with chronic wound infection were carried out using a standard Drip Flow Reactor (DFR) under conditions that mimic the flow of nutrients in the human skin. Anti-biofilm activity of chitosan gels and SSD showed a log-reduction of 6.0 for MRSA when chitosan gel with AgNPs at a concentration of 100 ppm was used, however it was necessary to increase the concentration of the chitosan gel with AgNPs to 1000 ppm to get a log-reduction of 3.3, while the SSD showed a total reduction of both bacteria in comparison with the negative control. The biocompatibility evaluation on primary fibroblasts showed better results when the chitosan gels with AgNPs were tested even in the high concentration, in contrast with SSD, which killed all the primary fibroblasts. In conclusion, chitosan gel formulations loaded with AgNPs effectively prevent the formation of biofilm and kill bacteria in established biofilm, which suggest that chitosan gels with AgNPs could be used for prevention and treatment of infections in chronic wounds. The statistic significance of the biocompatibility of chitosan gel formulations loaded with AgNPs represents an advance; however further research and development are necessary to translate this technology into therapeutic and

  9. Active screen plasma nitriding enhances cell attachment to polymer surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kaklamani, Georgia, E-mail: g.kaklamani@bham.ac.uk [University of Birmingham, College of Engineering and Physical Sciences, School of Metallurgy and Materials, Edgbaston, Birmingham B15 2TT (United Kingdom); Bowen, James; Mehrban, Nazia [University of Birmingham, College of Engineering and Physical Sciences, School of Chemical Engineering, Edgbaston, Birmingham B15 2TT (United Kingdom); Dong, Hanshan [University of Birmingham, College of Engineering and Physical Sciences, School of Metallurgy and Materials, Edgbaston, Birmingham B15 2TT (United Kingdom); Grover, Liam M. [University of Birmingham, College of Engineering and Physical Sciences, School of Chemical Engineering, Edgbaston, Birmingham B15 2TT (United Kingdom); Stamboulis, Artemis [University of Birmingham, College of Engineering and Physical Sciences, School of Metallurgy and Materials, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2013-05-15

    Active screen plasma nitriding (ASPN) is a well-established technique used for the surface modification of materials, the result of which is often a product with enhanced functional performance. Here we report the modification of the chemical and mechanical properties of ultra-high molecular weight poly(ethylene) (UHMWPE) using 80:20 (v/v) N{sub 2}/H{sub 2} ASPN, followed by growth of 3T3 fibroblasts on the treated and untreated polymer surfaces. ASPN-treated UHMWPE showed extensive fibroblast attachment within 3 h of seeding, whereas fibroblasts did not successfully attach to untreated UHMWPE. Fibroblast-coated surfaces were maintained for up to 28 days, monitoring their metabolic activity and morphology throughout. The chemical properties of the ASPN-treated UHMWPE surface were studied using X-ray photoelectron spectroscopy, revealing the presence of C-N, C=N, and C≡N chemical bonds. The elastic modulus, surface topography, and adhesion properties of the ASPN-treated UHMWPE surface were studied over 28 days during sample storage under ambient conditions and during immersion in two commonly used cell culture media.

  10. Polymer fractionation

    Energy Technology Data Exchange (ETDEWEB)

    Hadermann, A. F.

    1985-04-09

    Soluble polymers are fractionated according to molecular weight by cryogenically comminuting the polymer and introducing the polymer particles, while still in the active state induced by cryogenic grinding, into a liquid having a solvent power selected to produce a coacervate fraction containing high molecular weight polymer species and a dilute polymer solution containing lower molecular weight polymer species. The coacervate may be physically separated from the solution and finds use in the production of antimisting jet fuels and the like.

  11. Sol-gel derived multiwalled carbon nanotubes ceramic electrode modified with molecularly imprinted polymer for ultra trace sensing of dopamine in real samples

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, Bhim Bali, E-mail: prof.bbpd@yahoo.com [Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221 005 (India); Kumar, Deepak; Madhuri, Rashmi; Tiwari, Mahavir Prasad [Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221 005 (India)

    2011-08-01

    Highlights: > MWCNTs-CE was prepared by silane acrylate which provides a nanometer thin MIP film. > The sensor was modified by iniferter and MIP using 'surface grafting-from approach'. > A comparative study was performed between differentially designed ceramic electrodes. > The sensor can detect dopamine in real samples with LODs (0.143-0.154 ng mL{sup -1}). - Abstract: A new class of composite electrodes made of sol-gel derived ceramic-multiwalled carbon nanotubes is used for the growth of a nanometer thin film adopting 'surface grafting-from approach'. For this the multiwalled carbon nanotubes-ceramic electrode surface is first modified with an iniferter (benzyl N,N-diethyldithiocarbamate) and then dopamine imprinted polymer, under UV irradiation, for differential pulse anodic stripping voltammetric sensing of dopamine in aqueous, blood serum, cerebrospinal fluid, and pharmaceutical samples (detection limit 0.143-0.154 ng mL{sup -1}, 3{sigma}), without any cross reactivity, interferences and false-positive contributions. Such composite electrodes offer higher stability, electron kinetics, and renewable porous surface of larger electroactive area (with insignificant capacitance) than carbon ceramic electrodes. Additional cyclic voltammetry (stripping mode) and chronocoulometry experiments were performed to explore electrodics and kinetics of electro-oxidation of dopamine.

  12. A method for the quantitative analysis of Intensity-Modulated Radiation Therapy (IMRT) treatment plan verification with radiographic film and polymer gel dosimeters

    Science.gov (United States)

    Witten, Matthew Roy

    The clinical implementation of intensity-modulated radiotherapy has necessitated the development of sophisticated quality assurance techniques to ensure that the radiation dose distribution calculated by the computerized radiotherapy treatment planning system is reproduced with an acceptable degree of fidelity during treatment delivery. The index of agreement is introduced as a quantitative quality assurance tool capable of comparing the planned dose distribution with the dose distribution measured with a radiation dosimeter. The index of agreement method begins with solving a constrained optimization problem for each pixel (or voxel) of the planned dose distribution. Each pixel (or voxel) of the planned distribution is then assigned a score based upon the solution of the constrained optimization problem. The index of agreement is then calculated by dividing the number of pixels (or voxels) that are clinically relevant and for which the score function is equal to zero by the total number of clinically relevant pixels (or voxels). Data acquired with radiographic film and polymer gel indicate that the index of agreement is a stable quality assurance parameter.

  13. Separation and recovery of nucleic acids with improved biological activity by acid-degradable polyacrylamide gel electrophoresis.

    Science.gov (United States)

    Kim, Yoon Kyung; Kwon, Young Jik

    2010-05-01

    One of the fundamental challenges in studying biomacromolecules (e.g. nucleic acids and proteins) and their complexes in a biological system is isolating them in their structurally and functionally intact forms. Electrophoresis offers convenient and efficient separation and analysis of biomacromolecules but recovery of separated biomacromolecules is a significant challenge. In this study, DNAs of various sizes were separated by electrophoresis in an acid-degradable polyacrylamide gel. Almost 100% of the nucleic acids were recovered after the identified gel bands were hydrolyzed under a mildly acidic condition and purified using anion exchange resin. Further concentration by centrifugal filtration and a second purification using ion exchange column chromatography yielded 44-84% of DNA. The second conventional (non-degradable) gel electrophoresis confirmed that the nucleic acids recovered from acid-degradable gel bands preserved their electrophoretic properties through acidic gel hydrolysis, purification, and concentration processes. The plasmid DNA recovered from acid-degradable gel transfected cells significantly more efficiently than the starting plasmid DNA (i.e. improved biological activity via acid-degradable PAGE). Separation of other types of nucleic acids such as small interfering RNA using this convenient and efficient technique was also demonstrated.

  14. Photocatalytic properties of TiO2 bonded active carbon composites prepared by SOL-GEL

    Institute of Scientific and Technical Information of China (English)

    李佑稷; 李效东; 李君文; 尹静

    2004-01-01

    Photocatalyst of TiO2 bonded active carbon (TiO2/AC), was prepared via sol-gel method from a mixture of TiO2 sol with active carbon. Post heat treatment was performed at 250 ℃ for 2 h in air and then kept at 400 ℃ to 600 ℃ under a flow of nitrogen for 2 h. The TiO2/AC composites obtained were characterized by SEM, XRD, UV-vis and BET. The photocatalytic activities of the TiO2/AC composites were studied in comparison with TiO2, AC,P-25 and a mixture of TiO2 and AC, respectively. The Ramnant rate of Rhodamine B absorbed by the active carbon is found to be almost 70% and the remnant rates of the Rhodamine B decolorized by TiO2 and the mixture of TiO2 and the active carbon are 30% and 25%, respectively. However, nearly complete removal of Rhodamine B is observed for a TiO2/AC composite after 200 min under UV irradiation, which will take the P-25 commercial product 5 h. Therefore, the TiO2/AC composite is much more effective in decolorization of aqueous Rhodamine B. In addition, the composite can be easily separated from solutions.

  15. Scale dependence of mechanics and dynamics of active gels with increasing motor concentration

    CERN Document Server

    Sonn-Segev, Adar; Roichman, Yael

    2016-01-01

    The cytoskeleton protein actin assembles into large bundles when supporting stresses in the cell, but grows into a fine branched network to induce cell motion. Such self-organization processes are studied in artificial networks of cytoskeleton proteins with thick actin bundles and large motor protein aggregates to enable optical observation. The effect of motor aggregate size on the cytoskeleton mechanical properties is studied here in networks comprised of much smaller motor assemblies. Large motor protein clusters are known to increase the stiffness of actin based networks by introducing tension and additional cross-linking cites. We find that these effects are universal to actin gels regardless of actin bundle thickness and motor aggregate size and are relevant, therefore, to a wide range of cytoskeleton based cellular processes. In contrast, motor induced active fluctuations depend significantly on motor assembly size, featuring unique non-Gaussian statistics at high concentrations of small assemblies.

  16. 溶胶-凝胶法制备链霉素分子表面印迹聚合物及其性能表征%Preparation and characterization of streptomycin imprinted polymers by sol-gel method

    Institute of Scientific and Technical Information of China (English)

    李贤良; 侯长军; 郗存显; 王国明; 杨眉; 张雷; 李俊杰

    2013-01-01

    以四氢呋喃、乙醇和水的混合溶液(体积比6∶1∶1)为分散剂,3-氨基丙基三乙氧基硅烷和苯基三乙氧基硅烷为功能单体,正硅酸乙酯为交联剂,氨水为催化剂,通过溶胶-凝胶法在二氧化硅微球表面制备了分子印迹聚合物.用分子对接的方法初步分析了链霉素与功能单体和交联剂之间的相互作用,验证了它们形成氢键的可能性.活化时间会影响分子印迹微球的形貌.吸附实验表明,分子印迹微球比非印迹聚合物微球对链霉素具有更优越的吸附性能和选择性.%A mixed solution of tetrahydrofuran, ethanol and water (volume ratio is 6: 1:1) was chosen as dispersion agent, 3-aminopropyltriethoxysilane and phenyltriethoxysilane as functional monomers, and tet-raethyl orthosilicate as cross-linker, while ammonia solution served as catalyst, the preparation of molecu-larly imprinted polymers on the surface of silica microspheres by sol-gel method. Preliminary analysis of the interaction between the streptomycin and functional monomer and crosslinker with the molecular docking, verifying the forming hydrogen bond possibility. The activation time will affect the morphology of the molecularly imprinted microspheres. The absorption capacity and selectivity of the obtained molecularly imprinted polymers (MIPs) were also evaluated for streptomycin and its analogue compounds in water samples.

  17. A general approach toward enhancement of pseudocapacitive performance of conducting polymers by redox-active electrolytes

    KAUST Repository

    Chen, Wei

    2014-12-01

    A general approach is demonstrated where the pseudocapacitive performance of different conducting polymers is enhanced in redox-active electrolytes. The concept is demonstrated using several electroactive conducting polymers, including polyaniline, polypyrrole, and poly(3,4-ethylenedioxythiophene). As compared to conventional electrolytes, the redox-active electrolytes, prepared by simply adding a redox mediator to the conventional electrolyte, can significantly improve the energy storage capacity of pseudocapacitors with different conducting polymers. The results show that the specific capacitance of conducting polymer based pseudocapacitors can be increased by a factor of two by utilization of the redox-active electrolytes. In fact, this approach gives some of the highest reported specific capacitance values for electroactive conducting polymers. Moreover, our findings present a general and effective approach for the enhancement of energy storage performance of pseudocapacitors using a variety of polymeric electrode materials. © 2014 Elsevier B.V. All rights reserved.

  18. High Pressure Homogenization of Porcine Pepsin Protease: Effects on Enzyme Activity, Stability, Milk Coagulation Profile and Gel Development.

    Directory of Open Access Journals (Sweden)

    Bruno Ricardo de Castro Leite Júnior

    Full Text Available This study investigated the effect of high pressure homogenization (HPH (up to 190 MPa on porcine pepsin (proteolytic and milk-clotting activities, and the consequences of using the processed enzyme in milk coagulation and gel formation (rheological profile, proteolysis, syneresis, and microstructure. Although the proteolytic activity (PA was not altered immediately after the HPH process, it reduced during enzyme storage, with a 5% decrease after 60 days of storage for samples obtained with the enzyme processed at 50, 100 and 150 MPa. HPH increased the milk-clotting activity (MCA of the enzyme processed at 150 MPa, being 15% higher than the MCA of non-processed samples after 60 days of storage. The enzyme processed at 150 MPa produced faster aggregation and a more consistent milk gel (G' value 92% higher after 90 minutes when compared with the non-processed enzyme. In addition, the gels produced with the enzyme processed at 150 MPa showed greater syneresis after 40 minutes of coagulation (forming a more compact protein network and lower porosity (evidenced by confocal microscopy. These effects on the milk gel can be associated with the increment in MCA and reduction in PA caused by the effects of HPH on pepsin during storage. According to the results, HPH stands out as a process capable of changing the proteolytic characteristics of porcine pepsin, with improvements on the milk coagulation step and gel characteristics. Therefore, the porcine pepsin submitted to HPH process can be a suitable alternative for the production of cheese.

  19. High Pressure Homogenization of Porcine Pepsin Protease: Effects on Enzyme Activity, Stability, Milk Coagulation Profile and Gel Development.

    Science.gov (United States)

    Leite Júnior, Bruno Ricardo de Castro; Tribst, Alline Artigiani Lima; Cristianini, Marcelo

    2015-01-01

    This study investigated the effect of high pressure homogenization (HPH) (up to 190 MPa) on porcine pepsin (proteolytic and milk-clotting activities), and the consequences of using the processed enzyme in milk coagulation and gel formation (rheological profile, proteolysis, syneresis, and microstructure). Although the proteolytic activity (PA) was not altered immediately after the HPH process, it reduced during enzyme storage, with a 5% decrease after 60 days of storage for samples obtained with the enzyme processed at 50, 100 and 150 MPa. HPH increased the milk-clotting activity (MCA) of the enzyme processed at 150 MPa, being 15% higher than the MCA of non-processed samples after 60 days of storage. The enzyme processed at 150 MPa produced faster aggregation and a more consistent milk gel (G' value 92% higher after 90 minutes) when compared with the non-processed enzyme. In addition, the gels produced with the enzyme processed at 150 MPa showed greater syneresis after 40 minutes of coagulation (forming a more compact protein network) and lower porosity (evidenced by confocal microscopy). These effects on the milk gel can be associated with the increment in MCA and reduction in PA caused by the effects of HPH on pepsin during storage. According to the results, HPH stands out as a process capable of changing the proteolytic characteristics of porcine pepsin, with improvements on the milk coagulation step and gel characteristics. Therefore, the porcine pepsin submitted to HPH process can be a suitable alternative for the production of cheese.

  20. "JCE" Classroom Activity #106. Sequestration of Divalent Metal Ion by Superabsorbent Polymer in Diapers

    Science.gov (United States)

    Chen, Yueh-Huey; Lin, Jia-Ying; Lin, Li-Pin; Liang, Han; Yaung, Jing-Fun

    2010-01-01

    This activity explores an alternative use of a superabsorbent polymer known as a water absorbing material. A dilute solution of CuCl[subscript 2] is treated with a small piece of unused disposable diaper containing superabsorbent sodium polyacrylates. The polymer is used for the removal of Cu[superscript 2+] ions from the solution. The…