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Sample records for gelled polymer systems

  1. In situ permeability modification using gelled polymer systems. Annual report, April 11, 1997--April 10, 1998

    Energy Technology Data Exchange (ETDEWEB)

    Green, D.W.; Willhite, G.P.; McCool, C.S.; Heppert, J.A.; Vossoughi, S.; Michnick, M.J.

    1998-09-01

    Results from a research program on the application of gelled polymer technology for in situ permeability modification are presented in this report. The objective of this technology when used with displacement processes such as waterflooding is to reduce the permeability in fractures and/or high permeability matrix zones to improve volumetric sweep efficiency of the displacement process. In production wells, the objective is to reduce water influx. The research program focused on five areas: Gel treatment in fractured systems; Gel treatment in carbonate rocks; In-depth placement of gels; Gel systems for application in carbon dioxide flooding; and Gel treatment in production wells. The research program is primarily an experimental program directed toward improving the understanding of gelled polymer systems and how these systems can be used to increase oil recovery from petroleum reservoirs. A summary of progress for research conducted in the second 12 month period of a 28 month program is described.

  2. In situ permeability modification using gelled polymer systems. Topical report, June 10, 1996--April 10, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Green, D.W.; Willhite, G.P.; McCool, C.S.; Heppert, J.A.; Vossoughi, S.

    1997-10-01

    Results from a research program on the application of gelled polymer technology for in situ permeability modification are presented in this report. The objective of this technology when used with displacement processes such as waterflooding is to reduce the permeability in fractures and/or high permeability matrix zones to improve volumetric sweep efficiency of the displacement process. In production wells, the objective is to reduce water influx. The research program is focused on five areas: gel treatment in fractured systems; gel treatment in carbonate rocks; in-depth placement of gels; gel systems for application in carbon dioxide flooding; and gel treatment in production wells. The research program is primarily an experimental program directed at improving the understanding of gelled polymer systems and how these systems can be used to increase oil recovery from petroleum reservoirs. A summary of progress for research conducted in the first 10 months of a 28 month program is described in the following sections.

  3. Improving reservoir conformance using gelled polymer systems. Eleventh quarterly report, April 1, 1995--June 30, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Green, D.W.; Willhite, G.P.; Buller, C.; McCool, S.; Vossoughi, S.; Michnick, M.

    1995-07-24

    The general objectives are to (1) to identify and develop gelled polymer systems which have potential to improve reservoir conformance of fluid displacement processes, (2) to determine the performance of these systems in bulk and in porous media, and (3) to develop methods to predict the capability of these systems to recover oil from petroleum reservoirs. This work focuses on three types of gel systems -- an aqueous polysaccharide (KUSP1) system that gels as a function of pH, the chromium(III)-polyacrylamide system and the aluminum citrate-polyacrylamide system. Laboratory research is directed at the fundamental understanding of the physics and chemistry of the gelation process in bulk form and in porous media. This knowledge will be used to develop conceptual and mathematical models of the gelation process. Mathematical models will then be extended to predict the performance of gelled polymer treatments in oil reservoirs. Technical progress is described for the following tasks: physical and chemical characterization of gel systems; mechanisms of in situ gelation; and mathematical modelling of the gel systems.

  4. Improving reservoir conformance using gelled polymer systems. Annual report, September 25, 1992--September 24, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Green, D.W.; Willhite, G.P.

    1994-08-01

    The general objectives of the research program are to (1) identify and develop gelled polymer systems which have potential to improve reservoir conformance of fluid displacement processes, (2) determine the performance of these systems in bulk and in porous media, and (3) develop methods to predict their performance in field applications. The research focuses on three types of gel systems-an aqueous polysaccharide (KUSPI) that gels as a function of pH, polyacrylamide or xanthan crosslinked by CR(III) and a polyacrylamide-aluminum citrate system. Work to date has focused primarily on development of a database, selection of systems, and work to characterize the gel/polymer physical properties and kinetics. The use of ester hydrolysis to control the rate of pH change of a gel system has been investigated and this approach to gel-time control shows promise. Extensive kinetic data were taken on the uptake of CR(III) oligomers by polyacrylamide. A model was developed which describes very well the monomer uptake rates. The model described the dimer uptake data less well and the trimer uptake data poorly. Studies of the flow and gelation in rock materials have been initiated. A mathematical model of rock-fluid interaction during flow of high pH solutions has been developed.

  5. Improving reservoir conformance using gelled polymer systems. Annual report, September 15, 1993--September 24, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Green, D.W.; Willhite, G.P.

    1995-07-01

    The objectives of the research program are to (1) identify and develop polymer systems which have potential to improve reservoir conformance of fluid displacement processes, (2) determine the performance of these systems in bulk and in porous media, and (3) develop methods to predict their performance in field applications. The research focuses on three types of aqueous gel systems - a polysaccharide (KUSP1) that gels as a function of pH, a polyacrylamide-chromium(III) system and a polyacrylamide-aluminum citrate system. This report describes work conducted during the second year of a three-year program. Progress was made in the utilization of KUSP1 as a gelling agent. It was shown that gels can be formed in situ in porous media using CO{sub 2} or ester hydrolysis to lower pH. An ester was identified that could be used in field-scale operations. It was determined that KUSP1 will form strong gels when ortho boric acid is added to the system. It was also determined, in cooperation with Abbott Laboratories, that KUSP1 can be produced on a commercial scale. Rheological studies showed that shear rate significantly affects gelation time and gel strength. The effect of rock-fluid interactions at alkaline conditions was examined experimentally and through mathematical modeling. A model was developed that treats non-equilibrium conditions and this is an improvement over previously published models.

  6. Improving reservoir conformance using gelled polymer systems. Annual report, September 25, 1994--September 24, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Green, D.W.; Willhite, G.P.

    1996-05-01

    The objectives of the research program are to (1) identify and develop polymer systems which have potential to improve reservoir conformance of fluid displacement processes, (2) determine the performance of these systems in bulk and in porous media, and (3) develop methods to predict their performance in field applications. The research focused on four types of gel systems -- KUSP1 systems which contain an aqueous polysaccharide designated KUSP1, phenolic-aldehyde systems composed of resorcinol and formaldehyde, colloidal-dispersion systems composed of polyacrylamide and aluminum citrate, and a chromium-based system where polyacrylamide is crosslinked by chromium(III). Gelation behavior of the resorcinol-formaldehyde systems and the KUSP1-borate system was examined. Size distributions of aggregates that form in the polyacrylamide-aluminum colloidal-dispersion gel system were determined. Permeabilities to brine of several rock materials were significantly reduced by gel treatments using the KUSP1 polymer-ester (monoethylphthalate) system, the KUSP1 polymer-boric acid system, and the sulfomethylated resorcinol-formaldehyde system. The KUSP1 polymer-ester system and the sulfomethylated resorcinol-formaldehyde system were also shown to significantly reduce the permeability to super-critical carbon dioxide. A mathematical model was developed to simulate the behavior of a chromium redox-polyacrylamide gel system that is injected through a wellbore into a multi-layer reservoir in which crossflow between layers is allowed. The model describes gelation kinetics and filtration of pre-gel aggregates in the reservoir. Studies using the model demonstrated the effect filtration of gel aggregates has on the placement of gel systems in layered reservoirs.

  7. Improving reservoir conformance using gelled polymer systems. Final report, September 25, 1992--July 31, 1996

    Energy Technology Data Exchange (ETDEWEB)

    Green, D.W.; Willhite, G.P.; Buller, C.; McCool, S.; Vossoughi, S.; Michnick, M.

    1997-06-01

    The objectives of the research program were to (1) identify and develop polymer systems which have potential to improve reservoir conformance of fluid displacement processes, (2) determine the performance of these systems in bulk and in porous media, and (3) develop methods to predict their performance in field applications. The research focused on four types of gel systems--KUSP1 systems that contain an aqueous polysaccharide designated KUSP1, phenolic-aldehyde systems composed of resorcinol and formaldehyde, colloidal-dispersion systems composed of polyacrylamide and aluminum citrate, and a chromium-based system where polyacrylamide is crosslinked by chromium(III). Gelation behavior of the resorcinol-formaldehyde systems and the KUSP1-borate system was examined. Size distributions of aggregates that form in the polyacrylamide-aluminum colloidal-dispersion gel system were determined. Permeabilities to brine of several rock materials were significantly reduced by gel treatments using the KUSP1 polymer-ester (monoethyl phthalate) system, the KUSP1 polymer-boric acid system, and the sulfomethylated resorcinol-formaldehyde system were also shown to significantly reduce the permeability to supercritical carbon dioxide. A mathematical model was developed to simulate the behavior of a chromium redox-polyacrylamide gel system that is injected through a wellbore into a multi-layer reservoir in which crossflow between layers is allowed. The model describes gelation kinetics and filtration of pre-gel aggregates in the reservoir. Studies using the model demonstrated the effect filtration of gel aggregates has on the placement of gel systems in layered reservoirs.

  8. In-situ gelling polymers for biomedical applications

    CERN Document Server

    2015-01-01

    This book presents the research involving in situ gelling polymers and can be used as a guidebook for academics, industrialists and postgraduates interested in this area. This work summaries the academic contributions from the top authorities in the field and explore the fundamental principles of in situ gelling polymeric networks, along with examples of their major applications. This book aims to provide an up-to-date resource of in situ gelling polymer research.

  9. A microbial trigger for gelled polymers

    Energy Technology Data Exchange (ETDEWEB)

    Bailey, S.; Bryant, R.; Zhu, T.

    1995-12-31

    A process using a microbially gelled biopolymer was developed and used to modify permeability in coreflood experiments. Alkaline-soluble curdlan biopolymer was mixed with microbial nutrients and acid-producing alkaliphilic bacteria, and injected into Berea sandstone cores. Concurrent bottle tests with the polymer solution were incubated beside the core. Polymer in the bottle tests formed rigid gel in 2-5 days at 27{degree}C. After 7 days incubation, 25-35 psi fluid pressure was required to begin flow through the cores. Permeability of the cores was decreased from 852 md to 2.99 md and from 904 md to 4.86 md, respectively, giving residual resistance factors of 334 and 186.

  10. Rheological properties of reversible thermo-setting in situ gelling solutions with the methylcellulose-polyethylene glycol-citric acid ternary system (2): Effects of various water-soluble polymers and salts on the gelling temperature.

    Science.gov (United States)

    Shimokawa, Ken-ichi; Saegusa, Katsuhiko; Ishii, Fumiyoshi

    2009-11-01

    The influences of various salts and water-soluble polymers on the phase transition temperature of thermo-setting gels prepared by combining methylcellulose (MC)-sodium citrate (SC)-polyethylene glycol (PEG) at appropriate ratios (the MC-SC-PEG system) were investigated. Concerning cations, comparison of the phase transition temperature between SC and tripotassium citrate (PC) showed a rapid increase in the viscosity of SC between 20 degrees C and 25 degrees C and an increase in the viscosity of PC between 30 degrees C and 35 degrees C. Concerning the valency of anions, comparisons among SC, disodium tartrate dihydrate (ST), disodium maleate hemihydrates (SM), and sodium sulfate (SS) showed a rapid increase in the viscosity of trivalent SC between 20 degrees C and 25 degrees C and changes in the viscosity of the three bivalent sodium salts (ST, SM, and SS) at > or =30 degrees C. Thus the phase transition temperature decreased with an increase in the valency of anions. Subsequently, the influences of various water-soluble polymers on the gelling temperature were compared. Using polyvinylpyrrolidone (PVP) instead of PEG, the gelling temperature decreased with an increase in the PVP concentration even without the addition of SC. Unlike PVP, the addition of xanthan gum as a viscosity-increasing polysaccharide did not reduce the gelling temperature irrespective of its concentration. Temperature-associated changes in viscosity were observed at a fixed SC concentration with changes in the concentration of PVP or PEG. The gel phase transition temperature increased from 46 degrees C to 50 degrees C in gels not containing PVP or PEG. The viscosity did not differ between the addition of PVP or PEG at a low concentration and its absence. However, the viscosity clearly changed after the addition of each agent at a high concentration.

  11. Effect of polymer composition on rheological and degradation properties of temperature-responsive gelling systems composed of acyl-capped PCLA-PEG-PCLA.

    Science.gov (United States)

    Petit, Audrey; Müller, Benno; Meijboom, Ronald; Bruin, Peter; van de Manakker, Frank; Versluijs-Helder, Marjan; de Leede, Leo G J; Doornbos, Albert; Landin, Mariana; Hennink, Wim E; Vermonden, Tina

    2013-09-09

    In this study, the ability to modulate the rheological and degradation properties of temperature-responsive gelling systems composed of acyl-capped poly(ε-caprolactone-co-lactide)-b-poly(ethylene glycol)-b-poly(ε-caprolactone-co-lactide) (PCLA-PEG-PCLA) triblock copolymers was investigated. Eight polymers with varying molecular weight of PCLA, caproyl/lactoyl ratio (CL/LA) and capped with either acetyl- or propionyl-groups were synthesized by ring-opening polymerization of L-lactide and ε-caprolactone in toluene using PEG as initiator and tin(II) 2-ethylhexanoate as catalyst, and subsequently reacted in solution with an excess of acyl chloride to yield fully acyl-capped PCLA-PEG-PCLA. The microstructure of the polymers was determined by (1)H NMR, and the thermal properties and crystallinity of the polymers in dry state and in 25 wt % aqueous systems were studied by differential scanning calorimetry and X-ray diffraction. Rheological and degradation/dissolution properties of aqueous systems composed of the polymers in 25 wt % aqueous systems were studied. (1)H NMR analysis revealed that the monomer sequence in the PCLA blocks was not fully random, resulting in relatively long CL sequences, even though transesterification was demonstrated by the enrichment with lactoyl units and the presence of PEG-OH end groups. Except the most hydrophilic polymer composed of acetyl-capped PCLA1400-PEG1500-PCLA1400 having a CL/LA molar ratio of 2.5, the polymers at 25 wt % in buffer were sols below room temperature and transformed into gels between room temperature and 37 °C, which makes them suitable as temperature-responsive gelling systems for drug delivery. Over a period of weeks at 37 °C, the systems containing polymers with long CL sequences (~8 CL) and propionyl end-groups became semicrystalline as shown by X-ray diffraction analysis. Degradation of the gels by dissolution at 37 °C took 100-150 days for the amorphous gels and 250-300 days for the semicrystalline gels

  12. In situ gelling systems of ofloxacin: Comparative performance of in vivo precorneal drainage and pharmacokinetic study

    OpenAIRE

    Vrushali S Kashikar; Indrajeet D Gonjari

    2013-01-01

    Our present work describes the formulation and evaluation of an ocular deliver system of ofloxacin based on the concept of temperature-and ion-activated in situ gelling system. A combination of Pluronic F-127 and Pluronic F-68 along with chitosan, (pH-sensitive polymer also acts as a permeation enhancer) was used in temperature and pH-triggered in situ gelling systems while gellan alone was used in ion-activated in situ gelling system. The formulation allows its easy instillation into the eye...

  13. In situ gelling systems of ofloxacin: Comparative performance of in vivo precorneal drainage and pharmacokinetic study

    Directory of Open Access Journals (Sweden)

    Vrushali S Kashikar

    2013-01-01

    Full Text Available Our present work describes the formulation and evaluation of an ocular deliver system of ofloxacin based on the concept of temperature-and ion-activated in situ gelling system. A combination of Pluronic F-127 and Pluronic F-68 along with chitosan, (pH-sensitive polymer also acts as a permeation enhancer was used in temperature and pH-triggered in situ gelling systems while gellan alone was used in ion-activated in situ gelling system. The formulation allows its easy instillation into the eye as a liquid (drops, forms transparent gel, and spreads over the corneal surface. At the formulation pH, transcorneal permeation profile of ofloxacin was comparable to that of in vitro release profile. In situ gel-forming ability of the developed systems significantly controls precorneal drainage as studied by gamma scintigraphy. Thus, increased residence time in the eye would help to increase the ocular bioavailability. The formulation was also found to be nonirritant and well tolerable. Cmax of in situ gelling formulation was found to be 1.5 times higher than marketed eye drops solution at the similar Tmax of 1 h.

  14. Increased Oil Recovery from Mature Oil Fields Using Gelled Polymer Treatments

    Energy Technology Data Exchange (ETDEWEB)

    Willhite, G.P.; Green, D.W.; McCool, C.S.

    2001-01-22

    This report describes the progress of the first year of a three-year research program. This program is aimed at reducing barriers to the widespread use of gelled polymer treatments by (1) developing methods to predict gel behavior during placement in matrix rock and fractures, (2) determining the persistence of permeability reduction after gel placement, and (3) developing methods to design production well treatments to control water production.

  15. INCREASED OIL RECOVERY FROM MATURE OIL FIELDS USING GELLED POLYMER TREATMENTS

    Energy Technology Data Exchange (ETDEWEB)

    G.P. Willhite; D.W. Green; C.S. McCool

    2003-05-01

    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 a three-year research program aimed at reducing barriers to the widespread use of gelled polymer treatments by (1) developing methods to predict gel behavior during placement in matrix rock and fractures, (2) determining the persistence of permeability reduction after gel placement, and (3) developing methods to design production well treatments to control water production. The work focused on the gel system composed of polyacrylamide and chromium acetate. The molar mass of the polymer was about six million. Chromium(III) acetate reacted and formed crosslinks between polymer molecules. The crosslinked polymer molecules, or pre-gel aggregates, combine and grow to eventually form a 3-dimensional gel. A fundamental study to characterize the formation and growth of pre-gel aggregates was conducted. Two methods, flow field-flow fractionation (FFFF) and multi-angle laser light scattering (MALLS) were used. Studies using FFFF were inconclusive. Data taken using MALLS showed that at the gel time the average molar mass of gel aggregates increased by a factor of about three while the average size increase was approximately 50%. Increased acetate concentration in the gelant increases the gel time. The in situ performance of an added-acetate system was investigated to determine the applicability for in-depth treatments. Increased acetate concentrations delayed the development of increased flow resistance during gelant injection in short sandpacks. The development of increased flow resistance (in situ gelation) was extended from 2 to 34 days by increasing the acetate-to-chromium ratio from 38 to 153. In situ gelation occurred at a time that was approximately 22% of the bulk gelation time. When carbonate rocks are treated with gel, chromium retention in the rock may limit in

  16. Increased Oil Recovery from Mature Oil Fields Using Gelled Polymer Treatments

    Energy Technology Data Exchange (ETDEWEB)

    Willhite, G.P.; Green, D.W.; McCool, S.

    2001-03-28

    Gelled polymer treatments were applied to oil reservoirs to increase oil production and to reduce water production by altering the fluid movement within the reservoir. This report is aimed at reducing barriers to the widespread use of these treatments by developing methods to predict gel behavior during placement in matrix rock and fractures, determining the persistence of permeability reduction after gel placement, and by developing methods to design production well treatments to control water production. Procedures were developed to determine the weight-average molecular weight and average size of polyacrylamide samples in aqueous solutions. Sample preparation techniques were key to achieving reproducible results.

  17. Layered double hydroxides as an effective additive in polymer gelled electrolyte based dye-sensitized solar cells.

    Science.gov (United States)

    Ho, Hsu-Wen; Cheng, Wei-Yun; Lo, Yu-Chun; Wei, Tzu-Chien; Lu, Shih-Yuan

    2014-10-22

    Layered double hydroxides (LDH), a class of anionic clay materials, were developed as an effective additive for polymer gelled electrolytes for use in dye-sensitized solar cells (DSSC). Carbonate and chloride intercalated Zn-Al LDHs, ZnAl-CO3 LDH, and ZnAl-Cl LDH were prepared with coprecipitation methods. The addition of the two LDHs significantly improved, in terms of power conversion efficiency (PCE), over the plain poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) gelled electrolyte and competed favorably with the liquid electrolyte based DSSCs, 8.13% for the liquid electrolyte, 7.48% for the plain PVDF-HFP gelled electrolyte, 8.11% for the ZnAl-CO3 LDH/PVDF-HFP gelled electrolyte, and 8.00% for the ZnAl-Cl LDH/PVDF-HFP gelled electrolyte based DSSCs. The good performance in PCEs achieved by the LDH-loaded DSSCs came mainly from the significant boost in open circuit voltages (Voc), from 0.74 V for both the liquid electrolyte and PVDF-HFP gelled electrolyte based DSSCs to 0.79 V for both the ZnAl-CO3 LDH/PVDF-HFP and ZnAl-Cl LDH/PVDF-HFP gelled electrolyte based DSSCs. The boost in Voc was contributed mainly by the positive shift in redox potential of the redox couple, I(-)/I3(-), as revealed from cyclic voltammetry analyses. As for the long-term stability, PCE retention rates of 96 and 99% after 504 h were achieved by the ZnAl-CO3 LDH/PVDF-HFP and ZnAl-Cl LDH/PVDF-HFP gelled electrolyte based DSSCs, respectively, appreciably better than 92% achieved by the liquid electrolyte based one after 480 h.

  18. Increased Oil Recovery from Mature Oil Fields Using Gelled Polymer Treatments, Annual Report, June 16,2000-June 15, 2001

    Energy Technology Data Exchange (ETDEWEB)

    Willhite, G.P.; Green, D.W.; McCool, C.S.

    2002-05-22

    This program was aimed at reducing barriers to the widespread use of gelled polymer treatments by (1) developing methods to predict gel behavior during placement in matrix rock and fractures, (2) determining the persistence of permeability reduction after gel placement, and (3) developing methods to design production well treatments to control water production.

  19. FORMULATION AND ASSESSMENT OF GEMIFLOXACIN MESYLATE OCULAR IN SITU GELLING SYSTEM

    Directory of Open Access Journals (Sweden)

    Rajalakshmi R

    2013-10-01

    Full Text Available In situ gels are one of the most successful means of delivering the drug at ocular site with maximum bioavailability, which undergoes gelation upon instillation as drops into the eye due to physicochemical changes inherent to the biological fluids. The main aim of the present investigation was to obtain an ophthalmic drug delivery system with improved mucoadhesive and mechanical properties that could provide extended retention time for the treatment of ocular infections. For this in situ gels of Gemifloxacin Mesylate comprised of the combination of a thermosetting polymer, polaxamer with a mucoadhesive agent chitosan was developed. Fourier Transform Infrared Spectroscopy (FTIR and Differential Scanning Calorimetry techniques (DSC were performed to know the compatibilities between drug and polymer. FTIR spectra and DSC thermograph of Gemifloxacin Mesylate formulations showed that there is no chemical interaction between drug and polymer and confirmed the stability of the drug. The gels were evaluated for pH, Gel strength, Gelling capacity, Rheology, Drug content uniformity and Ocular irritancy studies. In vitro drug release studies reveal that all the formulations showed sustained release of the drug in the range of 70.82 to 76.43 % for a period of 8 h. The optimized formulation was tested for ocular irritation study on male albino rabbit and the result indicated that the formulation was well tolerated, non-irritating and therapeutically efficacious. In conclusion in situ gelling systems containing polaxamer / chitosan solution are viable alternative to enhance bioavailability thus leads to an excellent potential alternative ophthalmic sustained-release formulation of Gemifloxacin Mesylate in ocular infections.

  20. Thiolated poly(aspartic acid) as potential in situ gelling, ocular mucoadhesive drug delivery system.

    Science.gov (United States)

    Horvát, Gabriella; Gyarmati, Benjámin; Berkó, Szilvia; Szabó-Révész, Piroska; Szilágyi, Barnabás Áron; Szilágyi, András; Soós, Judit; Sandri, Giuseppina; Bonferoni, Maria Cristina; Rossi, Silvia; Ferrari, Franca; Caramella, Carla; Csányi, Erzsébet; Budai-Szűcs, Mária

    2015-01-25

    The ophthalmic formulations on the market suffer from poor bioavailability, and it would therefore be useful to design a new formulation which is able to prolong the residence time and reduce the administration frequency. Polymer matrices which exhibit strong mucoadhesion are promising platforms in ocular drug delivery from the aspect of improved bioavailability. In the present study, an in situ gelling, mucoadhesive drug delivery system was fabricated from thiolated poly(aspartic acid) (ThioPASP). The thiol groups of ThioPASP are able to form disulphide linkages with the mucin glycoproteins and prolong the residence time on the eye. The effects of the thiol groups on the structure, swelling behaviour and mucoadhesive character of the gel and on the drug release profile were determined. The gel structure was characterized by means of rheology. The ThioPASP gel was demonstrated by rheology, tensile test and 'wash away' measurements to display strong mucoadhesion. The drug release from the ThioPASP gel was studied on a vertical Franz diffusion cell: a burst release of sodium diclofenac occurred in the first hour, followed by sustained release of the encapsulated drug for up to 24h. The results proved the importance of the presence of the thiol groups and suggested that a ThioPASP formulation can be useful as an in situ gelling, ocular dosage form. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Food gels: gelling process and new applications.

    Science.gov (United States)

    Banerjee, Soumya; Bhattacharya, Suvendu

    2012-01-01

    Food gels are viscoelastic substances and several gelled products are manufactured throughout the world. The gelling agents in foods are usually polysaccharides and proteins. In food gels, the polymer molecules are not cross-linked by covalent bonds with the exception of disulphide bonds in some protein gels. Instead, the molecules are held together by a combination of weak inter-molecular forces like hydrogen bonds, electrostatic forces, Van der Waals forces, and hydrophobic interactions. Polysaccharides including hydrocolloids are strongly hydrated in aqueous medium but they tend to have less ordered structures. The mechanism of gelation depends on the nature of the gelling agent(s) and on the conditions of gel formation like the temperature, the presence of ions, the pH, and the concentration of gelling agents, etc. Characterization of gels can be performed in several ways of which rheological measurements are frequently practiced. Multi-component or mixed gel system is an important area of interest in which two or more gelling components are simultaneously used to achieve certain specific structural and functional characteristics. We here discuss about the different gels and gelling agents, the characterization of gels, and the mechanism of gelation with an emphasis on mixed or multi-component gels that would have significant commercial applications.

  2. PCL-based thermo-gelling polymers for in vivo delivery of chemotherapeutics to tumors.

    Science.gov (United States)

    Zheng, Chaohui; Gao, Hongzhi; Yang, Da-Peng; Liu, Minghuan; Cheng, Hongwei; Wu, Yun-Long; Loh, Xian Jun

    2017-05-01

    The synthesis of a multiblock poly(ether ester urethane)s comprising poly(ε-caprolactone), poly(ethylene glycol), and poly(propylene glycol) segments is described. We found that this polymer possessed a critical thermo-gelation concentration of 4wt%. Molecular characterization of the polymer was performed in terms of molecular weight determination, chemical composition elucidation and functional group determination using GPC, NMR, and FTIR. We carried out in vitro paclitaxel and doxorubicin release studies and demonstrated that sustained therapeutic release of about 2weeks can be obtained with this system. A nude mice model of tumor was developed and intratumoral injection of therapeutic-loaded thermo-gel demonstrated that PTX-loaded thermo-gel effectively inhibited the growth of tumors.

  3. Nanoparticles laden in situ gelling system for ocular drug targeting

    Directory of Open Access Journals (Sweden)

    Divya Kumar

    2013-01-01

    Full Text Available Designing an ophthalmic drug delivery system is one of the most difficult challenges for the researchers. The anatomy and physiology of eye create barriers like blinking which leads to the poor retention time and penetration of drug moiety. Some conventional ocular drug delivery systems show shortcomings such as enhanced pre-corneal elimination, high variability in efficiency, and blurred vision. To overcome these problems, several novel drug delivery systems such as liposomes, nanoparticles, hydrogels, and in situ gels have been developed. In situ-forming hydrogels are liquid upon instillation and undergo phase transition in the ocular cul-de-sac to form viscoelastic gel and this provides a response to environmental changes. In the past few years, an impressive number of novel temperature, pH, and ion-induced in situ-forming systems have been reported for sustain ophthalmic drug delivery. Each system has its own advantages and drawbacks. Thus, a combination of two drug delivery systems, i.e., nanoparticles and in situ gel, has been developed which is known as nanoparticle laden in situ gel. This review describes every aspects of this novel formulation, which present the readers an exhaustive detail and might contribute to research and development.

  4. Formulation and evaluation of microemulsion-based in situ ion-sensitive gelling systems for intranasal administration of curcumin.

    Science.gov (United States)

    Wang, Shuang; Chen, Ping; Zhang, Lin; Yang, Chunfen; Zhai, Guangxi

    2012-12-01

    The purpose of our study was to develop a microemulsion-based in situ ion-sensitive gelling system for intranasal administration of curcumin. A new microemulsion composition for curcumin was optimized with the simple lattice design. And the microemulsion-based in situ ion-sensitive gelling system consisted of Capryol 90 as oil phase, Solutol HS15 as surfactant, Transcutol HP as cosurfactant and 0.3% DGG solution as water phase. The physicochemical properties such as morphology, droplet size distribution, zeta value and the in vitro release were investigated. In addition, the histological section studies on the reaction between the obtained formulation and nasal mucosa showed that the microemulsion-based in situ ion-sensitive gelling system could not produce obvious damage to nasal mucosa. The pharmacokinetics results showed that the absolute bioavailability of curcumin in the microemulsion-based in situ ion-sensitive gelling system was 55.82% by intranasal administration. And the brain targeting index (BTI) was 6.50, and in the tissue distribution experiment, the value of (AUC(brain)/AUC(blood)) following intranasal administration was higher than that following intravenous administration, suggesting that the obvious brain targeting property by nasal delivery be attributed to a direct nose-to-brain drug transport. It can be concluded that the microemulsion-based in situ gelling as an effective and safe vehicle could greatly enhance the in vivo absorption and facilitate the delivery of curcumin to brain by intranasal administration.

  5. Comparison of ion-activated in situ gelling systems for ocular drug delivery. Part 1: physicochemical characterisation and in vitro release.

    Science.gov (United States)

    Rupenthal, Ilva D; Green, Colin R; Alany, Raid G

    2011-06-15

    Conventional eye drops can result in poor drug bioavailability due to the unique ocular anatomy and physiology. Ion-activated in situ gelling systems are able to crosslink with cations present in the tear fluid, therefore forming a gel on the ocular surface, which results in prolonged corneal contact time. The present study compared a number of anionic polysaccharides (gellan gum, xanthan gum, carrageenan and alginate) to an uncharged (HPMC) and a positively charged (chitosan) polymer system with emphasis on the gelling behaviour, rheological and textural properties, gel microstructure, contact angle and in vitro release characteristics. All systems exhibited physically entangled polymer networks that were able to disentangle upon shear stress and significantly prolonged the in vitro release of a model hydrophilic drug compared to a solution. While systems based on HPMC and chitosan showed no structural changes upon addition of cations, formulations based on gellan gum and carrageenan demonstrated a remarkable increase in viscosity, pseudoplasticity and hardness upon addition of Ca(2+) and K(+) respectively. This renders them favourable for ocular use as they would gel once in contact with the cations of the tear fluid, thus reducing nasolacrimal drainage, but would thin upon shearing, preventing ocular irritation and therefore induced lacrimation.

  6. Modulating rheological and degradation properties of temperature-responsive gelling systems composed of blends of PCLA-PEG-PCLA triblock copolymers and their fully hexanoyl-capped derivatives.

    Science.gov (United States)

    Petit, Audrey; Müller, Benno; Bruin, Peter; Meyboom, Ronald; Piest, Martin; Kroon-Batenburg, Loes M J; de Leede, Leo G J; Hennink, Wim E; Vermonden, Tina

    2012-12-01

    In this study, the ability to modulate rheological and degradation properties of temperature-responsive gelling systems composed of aqueous blends of poly(ε-caprolactone-co-lactide)-b-poly(ethylene glycol)-b-poly(ε-caprolactone-co-lactide) (PCLA-PEG-PCLA) triblock copolymers (i.e. uncapped) and their fully capped derivatives was investigated. Uncapped and capped PCLA-PEG-PCLA triblock copolymers, abbreviated as degree of modification 0 and 2 (DM0 and DM2, respectively), were composed of identical PCLA and PEG blocks but different end groups: namely hydroxyl and hexanoyl end groups. DM0 was synthesized by ring opening polymerization of l-lactide and ε-caprolactone in toluene using PEG as initiator and tin(II) 2-ethylhexanoate as the catalyst. A portion of DM0 was subsequently reacted with an excess of hexanoyl chloride in solution to yield DM2. The cloud point and phase behaviour of DM0 and DM2 in buffer as well as that of their blends were determined by light scattering in a diluted state and by vial tilting and rheological measurements in a concentrated state. Degradation/dissolution properties of temperature-responsive gelling systems were studied in vitro at pH 7.4 and 37°C. The cloud points of DM0/DM2 blends were ratio-dependent and could be tailored from 15 to 40°C for blends containing 15 to 100wt.% DM0. Vial tilting and rheological experiments showed that, with solid contents between 20 and 30wt.%, DM0/DM2 blends (15/85 to 25/75w/w) had a sol-to-gel transition temperature at 10-20°C, whereas blends with less than 15wt.% DM0 formed gels below 4°C and the ones with more than 25wt.% DM0 did not show a sol-to-gel transition up to 50°C. Complete degradation of temperature-responsive gelling systems took ∼100days, independent of the DM0 fraction and the initial solid content. Analysis of residual gels in time by GPC and (1)H-NMR showed no chemical polymer degradation, but indicated gel degradation by dissolution. Preferential dissolution of lactoyl

  7. Formulation and evaluation of in situ gelling systems for intranasal administration of gastrodin.

    Science.gov (United States)

    Cai, Zheng; Song, Xiangrong; Sun, Feng; Yang, Zhaoxiang; Hou, Shixiang; Liu, Zhongqiu

    2011-12-01

    Gastrodin is the major bioactive constituent of the traditional Chinese drug "Tianma." It is used in the treatment of some nervous system diseases and can be transported to the brain via intranasal administration. In the current paper, the development of a novel ion-activated in situ gelling system for the nasal delivery of gastrodin is discussed. An in situ perfusion model was used to determine the absorption-rate constant of gastrodin through rat nasal mucosa. The optimal formulation was determined by measuring the critical cation concentration, anti-dilution capacity, gel expansion coefficient, water-holding capacity, and adhesive capacity. The best formulation consisted of 10% gastrodin, 0.5% deacetylated gellan gum as the gelatinizer, and 0.03% ethylparaben as the preservative. The rheological properties of gastrodin nasal in situ gels were also investigated. The viscosity and elasticity sharply increased at temperatures below 25°C. When physiological concentrations of cations were added into the preparation, the mixture gelled into a semi-solid. The results of an accelerated stability test show that gastrodin nasal in situ gels can be stable for more than 2 years. Mucociliary toxicity was evaluated using the in situ toad palate model and the rat nasal mucociliary method; both models demonstrated no measurable ciliotoxicity. Pharmacodynamic studies suggest that similar acesodyne and sedative effects were induced following intranasal administration of 50 mg/kg gastrodin nasal in situ gels or oral administration of 100 mg/kg gastrodin solution. The in situ gel preparation is a safe and effective nasal delivery system for gastrodin.

  8. Applications of Optical Sensors to the Detection of Light Scattered from Gelling Systems

    Science.gov (United States)

    Bulone, Donatella; Manno, Mauro; San Biagio, Pier Luigi; Martorana, Vincenzo

    Visible light, scattered within an angle of few degrees, (Small Angle Light Scattering, SALS) yields information on the spatial correlations and dynamical properties on the scale of the micrometers. In this way a quick and non-invasive characterization of a variety of samples is feasible. Lately the SALS instruments have been built around multielement optical sensors (CCD, CMOS), allowing the simultaneous measurement of the complete structure factor even during fast kinetics. An assessment of some sensor matrices of different technology will be presented. The omolecular assemblies produced by polysaccharides or proteins can be functional or dysfunctional, their properties being either desirable or detrimental. Anyhow, their morphology often depends, in a very delicate way, on the presence of cosolutes, on the thermal history, on the biopolymer concentration etc. We present some applications of low angle dynamic and static light scattering to the study of gelling systems (agarose, pectin, insulin).

  9. Study and Application of Gelling Water Shutoff and Profile Control Agents

    Institute of Scientific and Technical Information of China (English)

    Wang Hongguan; Yu Liancheng; Tian Hongkun; Xu Yanxing

    1997-01-01

    @@ Oilfield Chemistry Department, Research Institute of Petroleum Exploration and Development, has made great efforts to study and develop oil chemicals since 1976.For many years, the systematic research has been done on the styles of polymers,crosslinking agents and addtional agents, which are primary components of the gelling systems,the chemical reaction process, the physical and chemical performance of final gelling forms,and the compatibility of chemicals with the different strata. The gelling systems adaptable to the different formations have been formed through these studies.

  10. Comparative study of polymer matrices for gelled electrolytes of lithium batteries; Etude comparative de matrices polymeres pour electrolytes gelifies de batteries au lithium

    Energy Technology Data Exchange (ETDEWEB)

    Du Pasquier, A.; Sarrazin, C.; Fauvarque, J.F. [CNAM, 75 - Paris (France); Andrieu, X. [Alcatel Alsthom Recherche, 91 - Marcoussis (France)

    1996-12-31

    A solid electrolyte for lithium batteries requires several properties: a good ionic conductivity of about 10{sup -3} S/cm at 298 deg. K, a high cationic transport number (greater than 0.5), a redox stability window higher than 4.5 V, a good stability of the interface with the lithium electrode, and a sufficient mechanical stability. The family of gelled or hybrid electrolytes seems to meet all these requirements. Thus, a systematic study of the gelling of an ethylene carbonate and lithium bistrifluorosulfonimide (LiTFSI) based electrolyte has been carried out. The polymers used for gel or pseudo-gel synthesis are POE, PMMA and PAN which represent 3 different cases of interaction with the electrolyte. All the properties mentioned above have been studied according to the nature of the polymer and to the concentration of lithium salt, showing the advantages and drawbacks of each polymer. The possibility of using some of these gels in lithium-ion batteries has been tested by lithium intercalation tests in UF2 graphite at the C/10 regime and by the cycling of LiCoO{sub 2}/UF{sub 2} batteries at the C/5 regime. Interesting performances have been obtained on Li/PPy batteries which can operate at the 7.5 C regime. (J.S.)

  11. Gelled Electrolytes For Lithium Batteries

    Science.gov (United States)

    Nagasubramanian, Ganesan; Attia, Alan; Halpert, Gerald

    1993-01-01

    Gelled polymer electrolyte consists of polyacrylonitrile (PAN), LiBF4, and propylene carbonate (PC). Thin films of electrolyte found to exhibit stable bulk conductivities of order of 10 to the negative 3rd power S/cm at room temperature. Used in thinfilm rechargeable lithium batteries having energy densities near 150 W h/kg.

  12. Electrospray formation of gelled nano-aluminum microspheres with superior reactivity.

    Science.gov (United States)

    Wang, Haiyang; Jian, Guoqiang; Yan, Shi; DeLisio, Jeffery B; Huang, Chuan; Zachariah, Michael R

    2013-08-14

    Nanometallic fuels with high combustion enthalpy, such as aluminum, have been proposed as a potential fuel replacement for conventional metallic fuel to improve propellant performance in a variety of propulsive systems. Nevertheless, nanometallic fuels suffer from the processing challenges in polymer formulations such as increased viscosity and large agglomeration, which hinder their implementation. In this letter, we employ electrospray as a means to create a gel within a droplet, via a rapid, solvent evaporation-induced aggregation of aluminum nanoparticles, containing a small mass fraction of an energetic binder. The gelled aluminum microspheres were characterized and tested for their burning behavior by rapid wire heating ignition experiments. The gelled aluminum microspheres show enhanced combustion behavior compared to nanoaluminum, which possibly benefits from the nitrocellulose coating and the gelled microstructure, and is far superior to the corresponding dense micrometer-sized aluminum.

  13. Osteogenic efficiency of in situ gelling poloxamine systems with and without bone morphogenetic protein-2

    Directory of Open Access Journals (Sweden)

    A Rey-Rico

    2011-04-01

    Full Text Available In situ gelling solutions for minimally invasive local application of bone growth factors are attracting increasing attention as efficient and patient-friendly alternative to bone grafts and solid scaffolds for repairing bone defects. Poloxamines, i.e., X-shaped poly(ethylene oxide-poly(propylene oxide block copolymers with an ethylenediamine core (Tetronic®, were evaluated both as an active osteogenic component and as a vehicle for rhBMP-2 injectable implants. After cytotoxicity screening of various poloxamine varieties, Tetronic 908, 1107, 1301 and 1307 solutions were chosen as the most cytocompatible and their sol-to-gel transitions were rheologically characterized. Viscoelastic gels, formed at 37 ºC, sustained protein release under physiological-like conditions. Formulations of rhBMP-2 led to differentiation of mesenchymal stem cells to osteoblasts, quantified as alkaline phosphatase activity with a maximum at day 7, and to mineralized nodules. Interestingly, poloxamine solely gels led to an initial proliferation of the mesenchymal stem cells (first week, followed by differentiation to osteoblasts (second to third week. Histochemical analysis revealed that Tetronic 908 is only osteoinductive; Tetronic 1107 is mostly osteoinductive, although its use leads to a minor differentiation to adipocytes; Tetronic 1307, solely or loaded with rhBMP-2, causes differentiation of both osteoblasts and adipocytes. Enhanced expression levels of CBFA-1 and collagen type I were observed for Tetronic 908, 1107 and 1307, both solely and combined with rhBMP-2. The intrinsic osteogenic activity of poloxamines (not observed for Pluronic F127 offers novel perspectives for bone regeneration using minimally invasive procedures (i.e., injectable scaffolds and overcoming the safety and the cost/effectiveness concerns associated with large scale clinical use of recombinant growth factors.

  14. Tunable Optical Polymer Systems

    Science.gov (United States)

    2007-11-02

    outperforms almost all other organic polymer systems reported thus far, the introduction of the first multiple color LBL electrochrome , and development...thin films outperform previously reported LBL assembled films and approach integration capability for a number of electrochromic , sensing and...Zacharia, N; Hammond, P. T. “ Electrochromism of LBL assembled thin polymer films containing metal oxide nanoparticles,” American Chemical Society

  15. Thermosensitive and pH induced in situ ophthalmic gelling system for ciprofloxacin hydrochloride: hydroxypropyl-beta-cyclodextrin complex.

    Science.gov (United States)

    Başaran, Berrin; Bozkir, Asuman

    2012-01-01

    The prolonged residence of drug formulation in the ocular cavity is important for ocular drug delivery. The purpose of the present study was to develop ophthalmic in situ gelling systems of ciprofloxacin hydrochloride with reduced pre-corneal elimination in order to improve the bioavailability and therapeutic response. Hydroxypropyl-beta-cyclodextrin was used in order to increase the stability of ciprofloxacin hydrochloride. In situ gels were prepared based on the concept of thermosensitive and pH induced in situ gelation. The inclusion complex of ciprofloxacin hydrochloride with hydroxypropyl-beta-cyclodextrin was prepared at a 1:1 molar ratio. The complex formation was thoroughly confirmed using various techniques, including (1)H NMR spectroscopy, FTIR spectrophotometry and differential scanning calorimetry. Both pure ciprofloxacin HCI and the inclusion complex were individually used in the formulations. Formulations were successfully prepared which were liquid at room temperature and exhibited viscosity increase and gelation at ophthalmic temperature. As a result of antimicrobial efficacy and in vitro release experiments, the developed formulations were found therapeutically efficient and provided sustained release of the drug over an 8 h period. These systems can be more advantageous than conventional eye drops.

  16. The dual temperature/pH-sensitive multiphase behavior of poly(N-isopropylacrylamide-co-acrylic acid) microgels for potential application in in situ gelling system.

    Science.gov (United States)

    Xiong, Wei; Gao, Xiang; Zhao, Yanbing; Xu, Huibi; Yang, Xiangliang

    2011-05-01

    Poly(N-isopropylacrylamide-co-acrylic acid) microgels (PNA) may be an excellent formulation for in situ gelling system due to their high sensitivity and fast response rate. Four monodispersed PNA microgels with various contents of acrylic acid (AA) were synthesized by emulsion polymerization in this paper. Their hydrodynamic diameters decreased reversibly with both decreasing pH and increasing temperature. The dual temperature/pH-sensitivity was influenced by many factors such as AA content, cross-link density and ion strength. In addition, high concentration PNA dispersions underwent multiple phase transition according to different temperatures, pHs and concentrations, which were summarized in a 3D sol-gel phase diagram in this study. According to the sol-gel phase transition, 8% PNA-025 dispersion maintained a relatively low viscosity and favorable fluidity at pH 5.0 in the temperature range of 25-40°C, but it rapidly increased in viscosity at pH 7.4 and gelled at 37°C. This feature enabled the dual temperature/pH-sensitive microgels to overcome the troubles in syringing of temperature sensitive materials during the injection. Apart from this, PNA could form gel well in in vitro (e.g., medium and serum) and in in vivo with low cytotoxicity. Therefore, it is promising for PNA to be applied in the in situ gelling system.

  17. Supramolecular polymers in inhomogeneous systems

    NARCIS (Netherlands)

    Zweistra, H.J.A.

    2007-01-01

    This thesis describes theoretical results of supramolecular polymers in inhomogeneous systems. Supramolecular polymers are linear assemblies of which the monomers are joined by reversible bonds. Many types of supramolecular polymers have been synthesized in recent years. Moreover, there are numerous

  18. Gelled Complex Fluids: Combining Unique Structures with Mechanical Stability.

    Science.gov (United States)

    Stubenrauch, Cosima; Gießelmann, Frank

    2016-03-01

    Gelled complex fluids are soft materials in which the microstructure of the complex fluid is combined with the mechanical stability of a gel. To obtain a gelled complex fluid one either adds a gelator to a complex fluid or replaces the solvent in a gel by a complex fluid. The most prominent example of a "natural" gelled complex fluid is the cell. There are various strategies by which one can form a gelled complex fluid; one such strategy is orthogonal self-assembly, that is, the independent but simultaneous formation of two coexisting self-assembled structures within one system. The aim of this Review is to describe the structure and potential applications of various man-made gelled complex fluids and to clarify whether or not the respective system is formed by orthogonal self-assembly.

  19. Poly(ethylene oxide/propylene oxide) copolymer thermo-reversible gelling system for the enhancement of intranasal zidovudine delivery to the brain.

    Science.gov (United States)

    Ved, Parag M; Kim, Kwonho

    2011-06-15

    The purpose of this study was to investigate the olfactory transfer of zidovudine (ZDV) after intranasal (IN) administration and to assess the effect of thermoreversible gelling system on its absorption and brain uptake. The nasal formulation was prepared by dissolving ZDV in pH 5.5 phosphate buffer solution comprising of 20% polyethylene oxide/propylene oxide (Poloxamer 407, PLX) as thermoreversible gelling agent and 0.1% n-tridecyl-β-D-maltoside (TDM) as permeation enhancer. This formulation exhibited a sufficient stability and an optimum gelation profile at 27-30 °C. The in vitro permeation studies across the freshly excised rabbit nasal mucosa showed a 53% increase in the permeability of ZDV from the formulation. For in vivo evaluation, the drug concentrations in the plasma, cerebrospinal fluid (CSF) and six different regions of the brain tissues, i.e. olfactory bulb (OB), olfactory tract (OT), anterior, middle and posterior segments of cerebrum (CB), and cerebellum (CL) were determined by LC/MS method following IV and IN administration in rabbits at a dose of 1mg/kg. The IN administration of Poloxamer 407 and TDM based formulation showed a systemic bioavailability of 29.4% while exhibiting a 4 times slower absorption process (t(max) = 20 min) than control solution (t(max) = 5 min). The CSF and brain ZDV levels achieved after IN administration of the gelling formulation were approximately 4.7-56 times greater than those attained after IV injection. The pharmacokinetic and brain distribution studies revealed that a polar antiviral compound, ZDV could preferentially transfer into the CSF and brain tissue via an alternative pathway, possibly olfactory route after intranasal administration.

  20. Gelling nature of aluminum soaps in oils.

    Science.gov (United States)

    Wang, Xiaorong; Rackaitis, Mindaugas

    2009-03-15

    Aluminum soaps are notable for their ability to form soap-hydrocarbon gels of high viscosity. For more than half a century, it has been believed that the gelling mechanism is due to a formation of polymeric chains of aluminum molecules with the aluminum atoms linking along the axis and with the fatty acid chain extended sideways. Here we report results from an investigation using high-resolution electron microscopy and rheology measurements that clearly resolve the ambiguity. Our results reveal that the gelling mechanism stems from the formation of spherical nano-sized micelles from aluminum soap molecules, and those colloidal micelle particles then aggregate into networks of highly fractal and jammed structures. The earlier proposed polymer chain-like structure is definitely incorrect. The discovery of aluminum soap particles could expand application of these materials to new technologies.

  1. Aqueous two-phase system cold-set gelation using natural and recombinant probiotic lactic acid bacteria as a gelling agent.

    Science.gov (United States)

    Léonard, Lucie; Husson, Florence; Langella, Philippe; Châtel, Jean-Marc; Saurel, Rémi

    2016-05-01

    The present study aimed to entrap probiotic lactic acid bacteria (LAB) in a sodium alginate and sodium caseinate aqueous two-phase gel system. The natural acidifying properties of two therapeutic probiotic LAB were exploited to liberate calcium ions progressively from calcium carbonate (CaCO3), which caused the gelation of the co-existing phases. Bi-biopolymeric matrix gelation of GDL/CaCO3 or LAB/CaCO3 was monitored by dynamic rheological measurements, and the final gels were characterized by frequency dependence measurements and confocal laser scanning microscopy. Weak to strong gels were formed with an elastic modulus G' from 10 to 1.000Pa, respectively. After cold-set gelation of our system, confocal laser scanning microscopy showed spherical protein microdomains trapped within a calcium alginate network. LAB cells were stained to study their partition in the self-gelling matrices. Our LAB strains showed two different behaviors, which may relate to the exopolysaccharide production: (i) Lactobacillus plantarum CNRZ1997 cells were found mainly in continuous alginate networks, whereas (ii) Lactococcus lactis cells were localized in protein microdomains. This alginate-caseinate phase-separated system that was self-gelled by LAB cells may be an innovative approach for immobilizing and protecting LAB cells.

  2. Emulsifying and gelling properties of weakfish myofibrillar proteins as affected by squid mantle myofibrillar proteins in a model system

    Directory of Open Access Journals (Sweden)

    Daniela Mariel Suarez

    2014-03-01

    Full Text Available The aim of the present work was to investigate the physicochemical, biochemical and functional characteristics of both the myofibrils (MF and actomyosin (AM of squid mantle (Illex argentinus and weakfish (Cynoscion guatucupa muscles, and evaluate the influence of the addition of myofibrilar proteins from the squid mantle on the physicochemical and functional properties of those of the weakfish. After extraction, purification and characterization of the MF and AM of both species, emulsions of each protein fraction from each muscle were formulated. Mixtures of the MF or AM of both species were also analyzed. The emulsifying properties were monitoring using the Emulsifying Activity Index (EAI and Emulsion Stability (ES. In addition, gel pastes were formulated from the squid mantle, weakfish muscle and the mixture of both species, and the following functional properties of the gels assessed: water holding capacity, colour, textural profile analysis (TPA (hardness, elasticity, cohesiveness, gumminess and gel strength. The EAI values of emulsions formulated with the MF of the mantle were significantly (p<0.05 higher than those formulated from those of weakfish. The incorporation of squid MF in the mixture increased the EAI values. Conversely, the highest ES values were obtained with weakfish MF, and the incorporation of MF weakfish in the mixture increased the ES values. Similar EAI and ES behaviours were observed for the AM of the corresponding species. Irrespective of the thermal treatment, the gel strength of the gelled paste of squid muscle was significantly (p<0.05 lower than that of weakfish muscle and of those obtained with the different mixtures. The behaviours of the expressible moisture (EM from the gelled pastes were similar to those of gel strength. Irrespective of the thermal treatment, the pastes formulated with a high weakfish: mantle ratio showed less water loss. The gelled pastes of squid mantle showed the highest values for whiteness

  3. High Energy, Low Temperature Gelled Bi-Propellant Formulation for Long-Duration In-Space Propulsion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Development of a candidate bi-propellant system consisting of a gelled hydrocarbon fuel coupled with a highly energetic gelled oxidizer suitable for outer planetary...

  4. Moxifloxacin-Gelrite in situ ophthalmic gelling system against photodynamic therapy for treatment of bacterial corneal inflammation.

    Science.gov (United States)

    El-Laithy, Hanan M; Nesseem, Demiana I; El-Adly, Amira A; Shoukry, Meriana

    2011-10-01

    In this study, six in situ gelling formulations based on Gelrite were prepared and evaluated for the retained ophthalmic delivery of Moxifloxacin (Mox). The effectiveness of the best developed formula G5 was compared with photodynamic therapy (PDT), the recent expanding approach for the treatment of ophthalmologic disorders after the assessment of optimum photodynamic inactivation parameters that permit efficient pathogens eradication. It was found that, Staphylococcus aureus (S. aureus) (Gram-positive) was more susceptible to effective lethal photosensitization that reaches 93.5% reduction in viable count than Escherichia coli (E. coli) (Gramnegative) of 76.1% using 3 mg/mL Hematoporphyrin (HP), illuminated by 630 nm Light Emitting Diode (LED) at 9 J/cm(2) and incubated for 15 min. Following topical instillation of G5 to rabbits corneas, higher amount of Mox was retained in the aqueous humor up to 24 h with significant 6-fold increase in the C(max) and AUC((0-∞)) compared to vigamox commercial eye drops. After post corneal infection with S. aureus, both approaches were effectively treating the infection without causing ocular irritation or collateral damage to corneal tissue where G5 showed remarkable improvement after four days compared to seven days of PDT treatment.

  5. An in situ gelling liquid crystalline system based on monoglycerides and polyethylenimine for local delivery of siRNAs

    NARCIS (Netherlands)

    Borgheti-Cardoso, Lívia Neves; Depieri, Lívia Vieira; Kooijmans, Sander A A; Diniz, Henrique; Calzzani, Ricardo Alexandre Junqueira; De Carvalho Vicentini, Fabiana Testa Moura; Van Der Meel, Roy; De Abreu Fantini, Márcia Carvalho; Iyomasa, Mamie Mizusaki; Schiffelers, Raymond M.; Bentley, Maria Vitória Lopes Badra; Schiffelers, Raymond

    2015-01-01

    The development of delivery systems able to complex and release siRNA into the cytosol is essential for therapeutic use of siRNA. Among the delivery systems, local delivery has advantages over systemic administration. In this study, we developed and characterized non-viral carriers to deliver siRNA

  6. An in situ gelling liquid crystalline system based on monoglycerides and polyethylenimine for local delivery of siRNAs

    NARCIS (Netherlands)

    Borgheti-Cardoso, Lívia Neves; Depieri, Lívia Vieira; Kooijmans, Sander; Diniz, Henrique; Calzzani, Ricardo Alexandre Junqueira; De Carvalho Vicentini, Fabiana Testa Moura; van der Meel, Roy; De Abreu Fantini, Márcia Carvalho; Iyomasa, Mamie Mizusaki; Schiffelers, Raymond; Bentley, Maria Vitória Lopes Badra

    2015-01-01

    The development of delivery systems able to complex and release siRNA into the cytosol is essential for therapeutic use of siRNA. Among the delivery systems, local delivery has advantages over systemic administration. In this study, we developed and characterized non-viral carriers to deliver siRNA

  7. 'Living' controlled in situ gelling systems: thiol-disulfide exchange method toward tailor-made biodegradable hydrogels.

    Science.gov (United States)

    Wu, De-Cheng; Loh, Xian Jun; Wu, Yun-Long; Lay, Chee Leng; Liu, Ye

    2010-11-03

    A 'living' controlled hydrogel formation method was first reported to create loose and compact in situ biodegradable hydrogels. The method executed under mild reaction conditions can conveniently tailor the hydrogel properties, and it has the potential to develop into a powerful tool for the design, synthesis, and self-assembly of novel tailor-made biomaterials and drug delivery systems.

  8. Stochastic Models of Polymer Systems

    Science.gov (United States)

    2016-01-01

    field limit of a dynamical model for polymer systems, Science China Mathematics , (11 2012): 0. doi: TOTAL: 1 Number of Non Peer-Reviewed Conference...4.0 (4.0 max scale): Number of graduating undergraduates funded by a DoD funded Center of Excellence grant for Education , Research and Engineering...undergraduates funded by your agreement who graduated during this period and will receive scholarships or fellowships for further studies in science

  9. Nanosuspension based in situ gelling nasal spray of carvedilol: development, in vitro and in vivo characterization.

    Science.gov (United States)

    Saindane, Nilesh S; Pagar, Kunal P; Vavia, Pradeep R

    2013-03-01

    The objective of the present investigation was to develop in situ gelling nasal spray formulation of carvedilol (CRV) nanosuspension to improve the bioavailability and therapeutic efficiency. Solvent precipitation-ultrasonication method was opted for the preparation of CRV nanosuspension which further incorporated into the in situ gelling polymer phase. Optimized formulation was extensively characterized for various physical parameters like in situ gelation, rheological properties and in vitro drug release. Formation of in situ gel upon contact with nasal fluid was conferred via the use of ion-activated gellan gum as carrier. In vivo studies in rabbits were performed comparing the nasal bioavailability of CRV after oral, nasal, and intravenous administration. Optimized CRV nanosuspension prepared by combination of poloxamer 407 and oleic acid showed good particle size [d (0.9); 0.19 μm], zeta potential (+10.2 mV) and polydispersity (span; 0.63). The formulation containing 0.5% w/v gellan gum demonstrated good gelation ability and desired sustained drug release over period of 12 h. In vivo pharmacokinetic study revealed that the absolute bioavailability of in situ nasal spray formulation (69.38%) was significantly increased as compared to orally administered CRV (25.96%) with mean residence time 8.65 h. Hence, such in situ gel system containing drug nanosuspension is a promising approach for the intranasal delivery in order to increase nasal mucosal permeability and in vivo residence time which altogether improves drug bioavailability.

  10. Improvement in the in situ gelling properties of deacetylated gellan gum by the immobilization of thiol groups.

    Science.gov (United States)

    Krauland, Alexander H; Leitner, Verena M; Bernkop-Schnürch, Andreas

    2003-06-01

    The rheological properties of an in situ crosslinking thiolated deacetylated gellan gum were examined in vitro. Mediated by a carbodiimide, L-cysteine was covalently bound to deacetylated gellan gum (DGG). The deacetylated gellan gum-cysteine (DGG-Cys) conjugate displayed 216.53 +/- 59.54 micromol thiol groups per gram polymer (means +/- SD, n = 3). The thiolated polymer was capable of forming inter- and/or intramolecular disulfide bonds in aqueous solution (1.5%; m/m) at pH 7. After 6 h of incubation at room temperature, storage modulus, loss modulus, and complex viscosity increased 300-, 6.4-, and 26.6-fold, respectively, relative to the unthiolated polymer. Loss tangent of DGG-Cys was gel, whereas the corresponding unmodified polymer had a loss tangent of >1, indicating a fluid. Frequency sweep measurements demonstrated an increase in crosslinking of the thiolated polymer as a function of time. DGG-Cys appeared to be superior to the unmodified polymer also in the presence of physiological cation concentrations found (e.g., in tear fluid and nasal secretion), which is referred to rheological properties. The polymer generated within this study represents a promising novel excipient for various drug delivery systems in which in situ gelling properties are favorable.

  11. Gelled Propellants for Reduced Temperature Operation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal is responsive to NASA 2004 SBIR objectives (under Topic X6.05) seeking gelled propellant formulations "for long-duration missions involving low-power...

  12. New Polymer Electrolyte Cell Systems

    Science.gov (United States)

    Smyrl, William H.; Owens, Boone B.; Mann, Kent; Pappenfus, T.; Henderson, W.

    2004-01-01

    PAPERS PUBLISHED: 1. Pappenfus, Ted M.; Henderson, Wesley A.; Owens, Boone B.; Mann, Kent R.; Smyrl, William H. Complexes of Lithium Imide Salts with Tetraglyme and Their Polyelectrolyte Composite Materials. Journal of the Electrochemical Society (2004), 15 1 (2), A209-A2 15. 2. Pappenfus, Ted M.; Henderson, Wesley A.; Owens, Boone B.; Mann, Kent R.; Smyrl, William H. Ionic-liquidlpolymer electrolyte composite materials for electrochemical device applications. Polymeric Materials Science and Engineering (2003), 88 302. 3. Pappenfus, Ted R.; Henderson, Wesley A.; Owens, Boone B.; Mann, Kent R.; and Smyrl, William H. Ionic Conductivity of a poly(vinylpyridinium)/Silver Iodide Solid Polymer Electrolyte System. Solid State Ionics (in press 2004). 4. Pappenfus Ted M.; Mann, Kent R; Smyrl, William H. Polyelectrolyte Composite Materials with LiPFs and Tetraglyme. Electrochemical and Solid State Letters, (2004), 7(8), A254.

  13. Smart materials: in situ gel-forming systems for nasal delivery.

    Science.gov (United States)

    Karavasili, Christina; Fatouros, Dimitrios G

    2016-01-01

    In the last decade in situ gelling systems have emerged as a novel approach in intranasal delivery of therapeutics, capturing the interest of scientific community. Considerable advances have been currently made in the development of novel formulations containing both natural and synthetic polymers. In this paper we present recent developments on in situ gelling systems for nasal delivery, highlighting the mechanisms that govern their formation.

  14. Experimental Study on the Combustion and Microexplosion of Freely Falling Gelled Unsymmetrical Dimethylhydrazine (UDMH Fuel Droplets

    Directory of Open Access Journals (Sweden)

    Jianjun Wu

    2012-08-01

    Full Text Available The increasing demand for high energy density fuels and the concern for their safety have propelled research in the field of gelled propellants, where understanding the combustion of single gelled fuel droplets is the first stage to predict the spray combustion characteristics. The experiments utilized single-isolated freely falling gelled unsymmetrical dimethylhydrazine (UDMH droplets instead of the conventional suspended droplet approach, in order to eliminate the perturbation associated with the suspension mechanism. Morphological transformations of the gelled droplet involved in the combustion processes were monitored by employing a high-speed digital camera, while the effects of ambient pressure and oxygen concentration on burning rate constants were also studied. The experimental results show that four main phenomena (droplet deformation, bubble formation and growth, vapor jetting and luminous jetting flame with “horn” shape and three distinct phases were identified in the droplet combustion process; the high yield stress and polymer chain structure of polymer gellant are responsible for the appearance of bubbles with almost the same order of magnitude as the droplets. Increasing the ambient pressure can increase the burning rate, postpone the appearance of microexplosions, and weaken microexplosion intensity; while increasing the ambient oxygen concentration can promote the appearance of microexplosions, strengthen microexplosion intensity and increase the burning rate.

  15. Statistical thermodynamics of polymer quantum systems

    CERN Document Server

    Chacón-Acosta, Guillermo; Dagdug, Leonardo; Morales-Técotl, Hugo A

    2011-01-01

    Polymer quantum systems are mechanical models quantized similarly as loop quantum gravity. It is actually in quantizing gravity that the polymer term holds proper as the quantum geometry excitations yield a reminiscent of a polymer material. In such an approach both non-singular cosmological models and a microscopic basis for the entropy of some black holes have arisen. Also important physical questions for these systems involve thermodynamics. With this motivation, in this work, we study the statistical thermodynamics of two one dimensional {\\em polymer} quantum systems: an ensemble of oscillators that describe a solid and a bunch of non-interacting particles in a box, which thus form an ideal gas. We first study the spectra of these polymer systems. It turns out useful for the analysis to consider the length scale required by the quantization and which we shall refer to as polymer length. The dynamics of the polymer oscillator can be given the form of that for the standard quantum pendulum. Depending on the...

  16. Gelled membranes for Li and Li-ion batteries prepared by electrospinning

    Science.gov (United States)

    Bansal, D.; Meyer, B.; Salomon, M.

    Composite polymer gelled membranes have been prepared an electrospinning technique. Electrospinning of polymer fibers or electrospraying of particles is typically accomplished by applying a strong electric field (ca. 1-25 kV cm -1) to a polymer solution or slurry of solids in an appropriate solvent. The fibers are collected as a mat (membrane) on a grounded target such as Al, Cu, Ni, etc. Typical membranes (mats) consist of nanometer size fibers and have porosities of 65-85%. In the present paper, we describe the fabrication of electrospun membranes for use as gelled electrolytes in Li and Li-ion batteries. The electrospun polymer membranes used in this work are based on the polyimides (PIs) Matrimid and Ultem 1000. Pure PI membranes have been prepared, and blends of Matrimid and Ultem with PVdF-HFP and PAN have been studied in 250 mAh and 7 Ah Li-ion cells. Fully imidized polyimides such as Matrimid and Ultem 1000 do not form gels, and are used as a host matrix of high mechanical strength to immobilize the gelling constituents PVdF or PAN.

  17. Gelled membranes for Li and Li-ion batteries prepared by electrospinning

    Energy Technology Data Exchange (ETDEWEB)

    Bansal, D.; Meyer, B.; Salomon, M. [MaxPower, Inc., 141 Christopher Lane, Harleysville, PA 19438 (United States)

    2008-04-01

    Composite polymer gelled membranes have been prepared an electrospinning technique. Electrospinning of polymer fibers or electrospraying of particles is typically accomplished by applying a strong electric field (ca. 1-25 kV cm{sup -1}) to a polymer solution or slurry of solids in an appropriate solvent. The fibers are collected as a mat (membrane) on a grounded target such as Al, Cu, Ni, etc. Typical membranes (mats) consist of nanometer size fibers and have porosities of 65-85%. In the present paper, we describe the fabrication of electrospun membranes for use as gelled electrolytes in Li and Li-ion batteries. The electrospun polymer membranes used in this work are based on the polyimides (PIs) Matrimid and Ultem 1000. Pure PI membranes have been prepared, and blends of Matrimid and Ultem with PVdF-HFP and PAN have been studied in 250 mAh and 7 Ah Li-ion cells. Fully imidized polyimides such as Matrimid and Ultem 1000 do not form gels, and are used as a host matrix of high mechanical strength to immobilize the gelling constituents PVdF or PAN. (author)

  18. Biodegradable in situ gelling delivery systems containing pilocarpine as new antiglaucoma formulations: effect of a mercaptoacetic acid/N-isopropylacrylamide molar ratio

    Directory of Open Access Journals (Sweden)

    Lai JY

    2013-10-01

    Full Text Available Jui-Yang Lai Institute of Biochemical and Biomedical Engineering, Biomedical Engineering Research Center, Molecular Medicine Research Center, Chang Gung University, Taoyuan, Taiwan Abstract: Ocular drug delivery is one of the most commonly used treatment modalities in the management of glaucoma. We have recently proposed the use of gelatin and poly(N-isopropylacrylamide (PNIPAAm graft copolymers as biodegradable in situ forming delivery systems for the intracameral administration of antiglaucoma medications. In this study, we further investigated the influence of carrier characteristics on drug delivery performance. The carboxyl-terminated PNIPAAm samples with different molecular weights were synthesized by varying the molar ratio of mercaptoacetic acid (MAA/N-isopropylacrylamide (NIPAAm from 0.05 to 1.25, and were determined by end-group titration. The preparation of gelatin-g-PNIPAAm (GN copolymers from these thermoresponsive polymers was achieved using carbodiimide chemistry. Our results showed that the carboxylic end-capped PNIPAAm of high molecular weight may lead to the lower thermal phase transition temperature and slower degradation rate of GN vehicles than its low molecular weight counterparts. With a decreasing MAA/NIPAAm molar ratio, the drug encapsulation efficiency of copolymers was increased due to fast temperature-triggered capture of pilocarpine nitrate. The degradation of the gelatin network could greatly affect the drug release profiles. All of the GN copolymeric carriers demonstrated good corneal endothelial cell and tissue compatibility. It is concluded that different types of GN-based delivery systems exhibit noticeably distinct intraocular pressure-lowering effect and miosis action, thereby reflecting the potential value of a MAA/NIPAAm molar ratio in the development of new antiglaucoma formulations. Keywords: gelatin, poly(N-isopropylacrylamide, glaucoma, chain transfer agent, ocular drug delivery

  19. Polymer Energy Rechargeable System Battery Being Developed

    Science.gov (United States)

    Manzo, Michelle A.

    2003-01-01

    Long description. Illustrations of discotic liquid crystals, rod-coil polymers, lithium-ion conducting channel dilithium phthalocyanine (Li2Pc) from top and side, novel star polyethylene oxide structures, composite polyethylene oxide materials (showing polyethylene oxide + lithium salt, carbon atoms and oxygen atoms), homopolyrotaxanes, and diblock copolymers In fiscal year 2000, NASA established a program to develop the next generation, lithium-based, polymer electrolyte batteries for aerospace applications. The goal of this program, known as Polymer Energy Rechargeable Systems (PERS), is to develop a space-qualified, advanced battery system embodying polymer electrolyte and lithium-based electrode technologies and to establish world-class domestic manufacturing capabilities for advanced batteries with improved performance characteristics that address NASA s future aerospace battery requirements.

  20. Murray Gell-Mann, A Short Appreciation

    CERN Document Server

    Hartle, James B

    2015-01-01

    On September 25, 2014 Murray Gell-Mann was presented with the Helmholz Medal of the Berlin Brandenburg Academy of Sciences and Humanities in a ceremony at the Santa Fe Institute. The author, among others, was asked to speak for fifteen minutes on Murray and his accomplishments. The following is an edited transcription of the author's speaking text.

  1. Gelled colloidal crystals as tunable optical filters for spectrophotometers

    Science.gov (United States)

    Sugao, Yukihiro; Onda, Sachiko; Toyotama, Akiko; Takiguchi, Yoshihiro; Sawada, Tsutomu; Hara, Shigeo; Nishikawa, Suguru; Yamanaka, Junpei

    2016-08-01

    We examined the performance of charged colloidal crystals immobilized in a polymer gel as tunable optical filters. The colloidal crystals of charged silica particles (particle diameter = 121 nm; particle concentration = 3.5 vol %; and Bragg wavelength λB = 630-720 nm) were produced by unidirectional crystallization under a temperature gradient. Photocurable gelation reagents were dissolved in the sample beforehand; this enabled gel immobilization of the crystals under ultraviolet illumination. The crystals had dimensions of more than 25 mm2 in area and 1 mm in thickness, and spatial λB variations of less than 1%. Upon mechanical compression, λB values shifted linearly and reversibly over almost the entire visible spectrum. Using the gelled crystals as tunable optical filters, we measured the transmittance spectra of various samples and found them to be in close agreement with those determined using a spectrophotometer equipped with optical gratings.

  2. Formulation & Storage Studies on Hydrazine-Based Gelled Propellants.

    Directory of Open Access Journals (Sweden)

    Mohan Verma

    1996-12-01

    Full Text Available The current trend in the area of high energy storable liquid rocket propellant research is to develop gelled/metallized systems and to explore the feasibility of their application in rocket motors. The idea stems from the fact that the conversion of a conventional liquid propellant to a gelled state and its subsequent metallization has the potential to significantly enhance the performance and density specific impulse. However, it is mandatory that the gelation of the liquid propellant be brought about with a minimum concentration of gellant and the gel formed should show a shear-thinning behaviour and good storage life. Keeping this in view, an experimental program to prepare thixotropic gels of hydrazine and its methyl substitutedderivatives like monomethyl hydrazineand unsymmetrical dimethyl hydrazinewas conducted under ambient conditions. The gellants investigated included particulate, chemical and synthetic materials. The gelation of the liquid fuels ..ould be brought about with gellant concentration as low as I wt per cent in some cases. Metallized gels using up to 40 wt per cent of AlIMg metal powders could be formulated. These heterogeneous systems showed a reduction in critical gellant concentration with degree of metallization. Further, less gelation time is observed if the gellant concentration is kept fixed and metal content is increased. The storage studies on gelled systems conducted over a period of three months showed good stability. The metallized systems, however, showed the settling of metal powders in meagre concentration which does not pose a major problem as these gels could be re-homogenized with stirring.

  3. Flow visualization of a rocket injector spray using gelled propellant simulants

    Science.gov (United States)

    Green, James M.; Rapp, Douglas C.; Roncace, James

    1991-01-01

    A study was conducted at NASA-Lewis to compare the atomization characteristics of gelled and nongelled propellant simulants. A gelled propellant simulant composed of water, sodium hydroxide, and an acrylic acid polymer resin (as the gelling agent) was used to simulate the viscosity of an aluminum/PR-1 metallized fuel gel. Water was used as a comparison fluid to isolate the rheological effects of the water-gel and to simulate nongelled RP-1. The water-gel was injected through the central orifice of a triplet injector element and the central post of a coaxial injector element. Nitrogen gas flowed through the outer orifices of the triplet injector element and through the annulus of the coaxial injector element and atomized the gelled and nongelled liquids. Photographs of the water-gel spray patterns at different operating conditions were compared with images obtained using water and nitrogen. A laser light was used for illumination of the sprays. The results of the testing showed that the water sprays produced a finer and more uniform atomization than the water-gel sprays. Rheological analysis of the water-gel showed poor atomization caused by high viscosity of water-gel delaying the transition to turbulence.

  4. Polymer hybrid materials for planar optronic systems

    Science.gov (United States)

    Körner, Martin; Prucker, Oswald; Rühe, Jürgen

    2015-09-01

    Planar optronic systems made entirely from polymeric functional materials on polymeric foils are interesting architectures for monitoring and sensing applications. Key components in this regard are polymer hybrid materials with adjustable optical properties. These materials can then be processed into optical components such as waveguides for example by using embossing techniques. However, the resulting microstructures have often low mechanical or thermal stability which quickly leads to a degradation of the microstructures accompanied often by a complete loss of function. A simple and versatile way to increase the thermal and mechanical stability of polymers is to connect the individual chains to a polymer network by using thermally or photochemically reactive groups. Upon excitation, these groups form reactive intermediates such as radicals or nitrenes which then crosslink with adjacent C-H-groups through a C,H insertion reaction (CHic = C,H insertion based crosslinking). To generate waveguide structures a PDMS stamp is filled with the waveguide core material e.g. poly(methylmethacrylate) (PMMA), which is modified with a few mol% of the thermal crosslinker and hot embossed onto a foil substrate e.g. PMMA. In this one-step hot embossing process polymer ridge waveguides are formed and simultaneously the polymer becomes crosslinked. Due to the reaction across the boundary between waveguide and substrate it is also possible to combine initially incompatible polymers for the waveguide and the substrate foil. The thermomechanical properties of the obtained materials are studied.

  5. Polymer hydrogels as optimized delivery systems

    Energy Technology Data Exchange (ETDEWEB)

    Batista, Jorge G.S.; Varca, Gustavo H.C.; Ferraz, Caroline C.; Garrido, Gabriela P.; Diniz, Bruna M.; Carvalho, Vinicius S.; Lugao, Ademar B., E-mail: jorgegabriel@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    Hydrogels are formed by polymers capable of absorbing large quantities of water. They consist of one or more three-dimensionally structured polymer networks formed by macromolecular chains linked by covalent bonds-crosslinks - and physical interactions. The application of hydrogels, has been widely studied. Biodegradable synthetic or natural polymers such as chitosan, starch and poly-lactic-co-glycolic acid, have properties that allow the development of biodegradable systems for drug and nutraceutics delivery. This study aimed to develop polymeric hydrogels based on polyvinyl alcohol, polyacrylamide and polyvinylpyrrolidone using ionizing radiation in order to develop hydrogels for improved loading and release of compounds. Polymer solutions were solubilized in water and poured into thermoformed packages. After sealing, the material was subjected to γ-irradiation at 25kGy. The samples were assayed by means of mechanical properties, gel fraction and swelling degree. Nanostructure characterization was performed using Flory's equation to determine crosslinking density. The systems developed showed swelling degree and adequate mechanical resistance. The nanostructure evaluation showed different results for each system demonstrating the need of choosing the polymer based on the specific properties of each material. (author)

  6. Rivastigmine-loaded in situ gelling nanostructured lipid carriers for nose to brain delivery.

    Science.gov (United States)

    Wavikar, Preeti R; Vavia, Pradeep R

    2015-01-01

    In the current research work, rivastigmine (RV)-loaded in situ gelling nanostructured lipid carriers (NLCs) were developed for nose to brain delivery. NLCs were fabricated by ethanol injection method using glyceryl monosterate, Capmul MCM C8, Lecithin and Tween 80. NLCs showed average particle size of 123.2 ± 2.3 nm with entrapment efficiency of 68.34 ± 3.4%. DSC, XRD and IR studies showed complete amorphization and incorporation of the drug into nanoparticles. NLCs were incorporated into an in situ gelling system using 0.8% gellan gum and 15% Lutrol F 127. RV in situ gel showed excellent elasticity, rheology, mucoadhesion and adhesiveness to facilitate its adhesion to the upper nasal mucosa. NLC-based in situ gel showed a 2-fold increase in nasal permeation of the drug over plain RV solution. In situ gelling NLCs showed a 3-fold increase in enzyme inhibition efficacy.

  7. Evaluation of biocompatible stabilised gelled soya bean oil nanoparticles as new hydrophobic reservoirs.

    Science.gov (United States)

    Boudier, Ariane; Kirilov, Plamen; Franceschi-Messant, Sophie; Belkhelfa, Haouaria; Hadioui, Laila; Roques, Christine; Perez, Emile; Rico-Lattes, Isabelle

    2010-01-01

    Based on the organogel concept, in which an oil is trapped in a network of low-molecular-mass organic gelator fibres creating a gel, a formulation of gelled soya bean oil nanoparticles was evaluated for its capacity to form biocompatible hydrophobic reservoirs. The aqueous dispersions of nanoparticles were prepared by hot emulsification (T° > Tgel) and cooling at room temperature in the presence of polyethyleneimine (PEI). The dispersions were stabilised by the electrostatic interactions between the positively charged amino groups of the PEI and the negatively charged carboxylates of the gelator fibres present at the surface of the particles. The aqueous dispersions were highly stable (several months) and the gelled particles were able to entrap a hydrophobic fluorescent model molecule (Nile red), allowing testing in cells. The gelled oil nanoparticles were found to be biocompatible with the tested cells (keratinocytes) and had the ability to become rapidly internalised. Thus, organogel-based nanoparticles are a promising hydrophobic drug delivery system.

  8. Monitoring collagen gelling by elastic scattering spectroscopy (ESS)

    OpenAIRE

    Jawad, H.; Austwick, M.; MacRobert, S.; Kuraishi, A.; Tully, F.; Alkseeva, T.; Brown, R.

    2011-01-01

    Collagen is being used extensively in tissue engineering and on a larger scale in the field of cosmetic surgery. It is either used as a gel or plastically compressed sheet. The fundamental science behind collagen gelling has been studied but little is known about the precise timing of gelling and the variables that affect gelling in the first 30 minutes. Critically, before collagen can be engineered as a predictable functional material we must be able to control fibril aggregation and gel for...

  9. 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

  10. A new approach to model strain change of gelled waxy crude oil under constant stress

    DEFF Research Database (Denmark)

    Hou, Lei; Song, Changyu; Yan, Wei

    2014-01-01

    Deformation of gelled waxy crude oil with loaded stress is worthy of research for the flow assurance of pipelining system. A dispersion parameter was introduced to characterize the disruption degree of wax crystal structure in crude oil with shear action. Based on fractional calculus theory, a rh...

  11. Numerical solution of the polymer system

    Energy Technology Data Exchange (ETDEWEB)

    Haugse, V.; Karlsen, K.H.; Lie, K.-A.; Natvig, J.R.

    1999-05-01

    The paper describes the application of front tracking to the polymer system, an example of a nonstrictly hyperbolic system. Front tracking computes piecewise constant approximations based on approximate Remain solutions and exact tracking of waves. It is well known that the front tracking method may introduce a blow-up of the initial total variation for initial data along the curve where the two eigenvalues of the hyperbolic system are identical. It is demonstrated by numerical examples that the method converges to the correct solution after a finite time that decreases with the discretization parameter. For multidimensional problems, front tracking is combined with dimensional splitting and numerical experiments indicate that large splitting steps can be used without loss of accuracy. Typical CFL numbers are in the range of 10 to 20 and comparisons with the Riemann free, high-resolution method confirm the high efficiency of front tracking. The polymer system, coupled with an elliptic pressure equation, models two-phase, tree-component polymer flooding in an oil reservoir. Two examples are presented where this model is solved by a sequential time stepping procedure. Because of the approximate Riemann solver, the method is non-conservative and CFL members must be chosen only moderately larger than unity to avoid substantial material balance errors generated in near-well regions after water breakthrough. Moreover, it is demonstrated that dimensional splitting may introduce severe grid orientation effects for unstable displacements that are accentuated for decreasing discretization parameters. 9 figs., 2 tabs., 26 refs.

  12. Structure-property evaluation of thermally and chemically gelling injectable hydrogels for tissue engineering.

    Science.gov (United States)

    Ekenseair, Adam K; Boere, Kristel W M; Tzouanas, Stephanie N; Vo, Tiffany N; Kasper, F Kurtis; Mikos, Antonios G

    2012-09-10

    The impact of synthesis and solution formulation parameters on the swelling and mechanical properties of a novel class of thermally and chemically gelling hydrogels combining poly(N-isopropylacrylamide)-based thermogelling macromers containing pendant epoxy rings with polyamidoamine-based hydrophilic and degradable diamine cross-linking macromers was evaluated. Through variation of network hydrophilicity and capacity for chain rearrangement, the often problematic tendency of thermogelling hydrogels to undergo significant syneresis was addressed. The demonstrated ability to tune postformation dimensional stability easily at both the synthesis and formulation stages represents a significant novel contribution toward efforts to utilize poly(N-isopropylacrylamide)-based polymers as injectable biomaterials. Furthermore, the cytocompatibility of the hydrogel system under relevant conditions was established while demonstrating time- and dose-dependent cytotoxicity at high solution osmolality. Such injectable in situ forming degradable hydrogels with tunable water content are promising candidates for many tissue-engineering applications, particularly for cell delivery to promote rapid tissue regeneration in non-load-bearing defects.

  13. Enzymatically degradable temperature-sensitive polypeptide as a new in-situ gelling biomaterial.

    Science.gov (United States)

    Jeong, Yuri; Joo, Min Kyung; Bahk, Kyung Hyun; Choi, Yun Young; Kim, Ho-Tae; Kim, Won-Ki; Lee, Hwa Jeong; Sohn, Youn Soo; Jeong, Byeongmoon

    2009-07-01

    We are reporting a poly (ethylene glycol)-block-poly(alanine-co-phenyl alanine) (PEG-PAF) aqueous solution that undergoes sol-to-gel transition as the temperature increases. The sol-to-gel transition was observed at as low a concentration as 3.0-7.0 wt.%. Micellar aggregation accompanying small conformational changes of the peptide from random coils to beta-sheets is suggested as the sol-to-gel transition mechanism of the PEG-PAF aqueous solution. The PEG-PAF is stable in phosphate buffered saline, however, it degraded in the subcutaneous layer of rats. In vitro study showed that proteolytic enzymes such as cathepsin B, cathepsin C, and elastase that are present in the subcutaneous layer of the mammalian tissue might be responsible for the degradation of the polymer in rats. As a feasibility study of this material, a single shot of an aqueous insulin formulation (13.8 mg insulin/kg) showed a hypoglycemic effect over 18 days in rats. The current functional polypeptide may be very promising as an in-situ gelling system for tissue engineering, cell/stem cell therapy, and drug delivery.

  14. Polymers for hydrogen infrastructure and vehicle fuel systems :

    Energy Technology Data Exchange (ETDEWEB)

    Barth, Rachel Reina; Simmons, Kevin L.; San Marchi, Christopher W.

    2013-10-01

    This document addresses polymer materials for use in hydrogen service. Section 1 summarizes the applications of polymers in hydrogen infrastructure and vehicle fuel systems and identifies polymers used in these applications. Section 2 reviews the properties of polymer materials exposed to hydrogen and/or high-pressure environments, using information obtained from published, peer-reviewed literature. The effect of high pressure on physical and mechanical properties of polymers is emphasized in this section along with a summary of hydrogen transport through polymers. Section 3 identifies areas in which fuller characterization is needed in order to assess material suitability for hydrogen service.

  15. Heather Gell and Music Education in the Community

    Science.gov (United States)

    Nash, Sandra

    2014-01-01

    Kindergartener and Dalcroze teacher, Heather Gell (1896-1988), brought music to thousands of Australian children and adults. The community touched by Gell was vast: it included her classes in studios and teacher training colleges, "listeners in" to her radio programs, viewers of her television programs, Dalcroze trainees, and people in…

  16. The Peroxidase/H2O2 System as a Free Radical-Generating Agent for Gelling Maize Bran Arabinoxylans: Rheological and Structural Properties

    Directory of Open Access Journals (Sweden)

    Erika Salas-Muñoz

    2011-10-01

    Full Text Available The oxidative gelation of maize bran arabinoxylans (MBAX using a peroxidase/H2O2 system as a free radical-generating agent was investigated. The peroxidase/H2O2 system led to the formation of dimers and trimer of ferulic acid as covalent cross-link structures in the MBAX network. MBAX gels at 4% (w/v presented a storage modulus of 180 Pa. The structural parameters of MBAX gels were calculated from swelling experiments. MBAX gels presented a molecular weight between two cross-links (Mc, a cross-linking density (ρc and a mesh size (x of 49 × 103 g/mol, 30 × 10−6 mol/cm3 and 193 nm, respectively.

  17. Development of in situ gelling and bio adhesive 5-Fluorouracil enema.

    Science.gov (United States)

    Wang, Lu-Lu; Zheng, Wen-Sheng; Chen, Shao-Hua; Fang, Xia-Qin

    2013-01-01

    In this study, a novel 5-Fluorouracil (5-FU) enema with good bio adhesion and temperature sensitivity was developed using in situ gelling technology. The preparation was formulated as a free-flowing liquid before use, while a layer of gel film was quickly formed when administered in the rectum, with a large contact surface area. It also demonstrated good biocompatibility, appropriate gel strength and bio adhesive force with excellent adhesion to rectal mucosa and prolonged action time, allowing more effective drug absorption and diffusion to surrounding tissues. Poloxamer 407 and poloxamer 188 were applied to adjust the gelling temperature. With the addition of carbopol and polycarbophil (bio adhesive substances), the solubility of 5-FU and gel strength increased, the temperature of gelation and the surface area of drug contact on mucous epithelium decreased. Decreased adhesive force between the preparation and the mucous membrane of the rectum was demonstrated with improving carbopol and polycarbophil's concentration. In vitro release demonstrated that 5-FU in situ gelling enema with different bases had a rapid and almost complete drug release. We used an optimized formulation of P407/P188/polycarbophil/5-FU (17/2.5/0.2/1.0) for animal experiments. The result showed that the drug evenly covered the surface of the rectum and there was no leakage in 6 hours. The in situ gelling enema showed significantly higher rectal tissue levels of 5-FU compared with suppository and intravenous administration, indicating that 5-FU could be well absorbed due to the enlarged releasing area, longer retention time and larger amount of dissolved active ingredients. Systemically, 5-FU levels in the enema group were similar to those in the suppository group and significantly lower than the intravenous group. The enema was not associated with morphological damage to rectal tissue. These results suggest that the bio adhesive and in situ gelling enema could be a more effective rectal

  18. Development of in situ gelling and bio adhesive 5-Fluorouracil enema.

    Directory of Open Access Journals (Sweden)

    Lu-Lu Wang

    Full Text Available In this study, a novel 5-Fluorouracil (5-FU enema with good bio adhesion and temperature sensitivity was developed using in situ gelling technology. The preparation was formulated as a free-flowing liquid before use, while a layer of gel film was quickly formed when administered in the rectum, with a large contact surface area. It also demonstrated good biocompatibility, appropriate gel strength and bio adhesive force with excellent adhesion to rectal mucosa and prolonged action time, allowing more effective drug absorption and diffusion to surrounding tissues. Poloxamer 407 and poloxamer 188 were applied to adjust the gelling temperature. With the addition of carbopol and polycarbophil (bio adhesive substances, the solubility of 5-FU and gel strength increased, the temperature of gelation and the surface area of drug contact on mucous epithelium decreased. Decreased adhesive force between the preparation and the mucous membrane of the rectum was demonstrated with improving carbopol and polycarbophil's concentration. In vitro release demonstrated that 5-FU in situ gelling enema with different bases had a rapid and almost complete drug release. We used an optimized formulation of P407/P188/polycarbophil/5-FU (17/2.5/0.2/1.0 for animal experiments. The result showed that the drug evenly covered the surface of the rectum and there was no leakage in 6 hours. The in situ gelling enema showed significantly higher rectal tissue levels of 5-FU compared with suppository and intravenous administration, indicating that 5-FU could be well absorbed due to the enlarged releasing area, longer retention time and larger amount of dissolved active ingredients. Systemically, 5-FU levels in the enema group were similar to those in the suppository group and significantly lower than the intravenous group. The enema was not associated with morphological damage to rectal tissue. These results suggest that the bio adhesive and in situ gelling enema could be a more

  19. A Novel Pectin Material: Extraction, Characterization and Gelling Properties

    Directory of Open Access Journals (Sweden)

    Agustin Rascón-Chu

    2010-09-01

    Full Text Available A novel pectin was acid extracted from chickpea husk (CHP. CHP presented a 67% (w/w of galacturonic acid, an intrinsic viscosity of 374 mL/g and a viscosimetric molecular weight of 110 kDa. Fourier transform infrared spectroscopy spectrum of CHP indicated a degree of esterification of about 10%. The CHP-calcium system formed ionic gels with a storage (G’ modulus of 40 Pa and gel set time (G’ > G’’ of 3 min at 1% (w/v, and a G’ of 131 Pa and gel set time of 1 min at 2% (w/v. The G’ of CHP gels was not greatly affected by temperature. The results attained suggest that chickpea husk can be a potential source of a gelling pectin material.

  20. A novel pectin material: extraction, characterization and gelling properties.

    Science.gov (United States)

    Urias-Orona, Vania; Rascón-Chu, Agustin; Lizardi-Mendoza, Jaime; Carvajal-Millán, Elizabeth; Gardea, Alfonso A; Ramírez-Wong, Benjamín

    2010-09-28

    A novel pectin was acid extracted from chickpea husk (CHP). CHP presented a 67% (w/w) of galacturonic acid, an intrinsic viscosity of 374 mL/g and a viscosimetric molecular weight of 110 kDa. Fourier transform infrared spectroscopy spectrum of CHP indicated a degree of esterification of about 10%. The CHP-calcium system formed ionic gels with a storage (G') modulus of 40 Pa and gel set time (G' > G″) of 3 min at 1% (w/v), and a G' of 131 Pa and gel set time of 1 min at 2% (w/v). The G' of CHP gels was not greatly affected by temperature. The results attained suggest that chickpea husk can be a potential source of a gelling pectin material.

  1. Identification and Development of a Gelled Fuel through the Use of Liquid Gelling Agents

    Science.gov (United States)

    2008-02-01

    polyacrylic acid polymer (solid) that can be used to transform many liquid products into a gel. It is suggested for use as an all-purpose thickener and...Benzene and polystyrene • Aluminum soaps (e.g., aluminum stearate) • Alcohols plus laundry detergent (aluminum soaps) Although all systems above

  2. Nanostructures for all-polymer microfluidic systems

    DEFF Research Database (Denmark)

    Matschuk, Maria; Bruus, Henrik; Larsen, Niels Bent

    2010-01-01

    We present a process for fabricating nanostructured surfaces with feature sizes down to at least 50 nm and aspect ratios of 1:1 by injection molding. We explored the effects of mold coatings and injection molding conditions on the final nanostructure quality. A plasma-polymerized fluorocarbon based...... antistiction coating was found to improve the replication fidelity (shape and depth) of nanoscale features substantially. Arrays of holes of 50 nm diameter/35 nm depth and 100 nm/100 nm diameter, respectively, were mass-produced in cyclic olefin copolymer (Topas 5013) by injection molding. Polymer microfluidic...... channel chip parts resulted from a separate injection molding process. The microfluidic chip part and the nanostructured chip part were successfully bonded to form a sealed microfluidic system using air plasma assisted thermal bonding....

  3. Structural health monitoring system/method using electroactive polymer fibers

    Science.gov (United States)

    Scott-Carnell, Lisa A. (Inventor); Siochi, Emilie J. (Inventor)

    2013-01-01

    A method for monitoring the structural health of a structure of interest by coupling one or more electroactive polymer fibers to the structure and monitoring the electroactive responses of the polymer fiber(s). Load changes that are experienced by the structure cause changes in the baseline responses of the polymer fiber(s). A system for monitoring the structural health of the structure is also provided.

  4. Gelling properties of microparticulated whey proteins.

    Science.gov (United States)

    Dissanayake, Muditha; Kelly, Alan L; Vasiljevic, Todor

    2010-06-09

    Subjecting whey proteins to high-pressure shearing with or without heating, commonly termed microparticulation, results in novel ingredients with modulated functionalities. Gelling properties of microparticulated whey proteins (MWP) were specifically assessed in this study. MWP powders were produced from commercial cheese whey retentate, standardized to 10% (w/w) protein, and subjected to microfluidization (MFZ) at 140 MPa either with or without prior heat-induced denaturation, followed by spray-drying. Gels were created from aqueous MWP dispersions either by heating at 90 degrees C for 20 min or by allowing gels to form at ambient temperature through addition of glucano-delta-lactone and/or NaCl. MWP powders produced from unheated WP dispersions created firm gels upon heating, whereas those produced from denatured WP gave only cold-set gels. Covalent and noncovalent protein-protein interactions were involved during both heat- and cold-induced gelation. Hydrophobic interactions were more pronounced during aggregation of bovine serum albumin. In conclusion, microparticulation of WP resulted in heat- and cold-set gels with different molecular and physical characteristics from those of untreated controls.

  5. Design and Characterization of Bioadhesive In-Situ Gelling Ocular Inserts of Gatifloxacin Sesquihydrate

    Directory of Open Access Journals (Sweden)

    Mishra D.N.

    2008-03-01

    Full Text Available Background and purpose of the study: Several polymeric systems have been used to fabricate ocular inserts for better ocular bioavailability and retention to drug of which gelling systems have shown advantages of convenient administration and increased contact time. The purpose of the present study was to develop a bioadhesive in-situe gelling ocular insert of Gatifloxacin using polymeric system of sodium alginate as gelling and chitosan as bioadhesive agent.Materials and methods: Polymeric ocular inserts of Gatifloxacin sesquehydrate (GS were composed using sodium alginate and chitosan with glycerin as plasticizer by solvent casting method. The ocular inserts were investigated for physicochemical properties (thickness, weight variation, folding endurance and surface pH, mechanical strength (tensile strength, elongation at break, swelling index, and bioadhesion parameters. In vitro release studies were carried using a fabricated donor-receptor compartment model. Results: Cumulative drug released from the formulation ranged from 95-99% within 8-12h. The formulation D (2% sodium alginate and 1% chitosan sustained the drug release for the longest period of time (12h. Zero-order release of the drug was from optimized formulation D. A high correlation coefficient (r=0.9845 was recorded between in vitro and in vivo drug release.Conclusion: Gatifloxacin sesquehydrate inserts have appreciable film forming properties and were found to posses good antimicrobial efficacy.

  6. Thiolated polymers as mucoadhesive drug delivery systems.

    Science.gov (United States)

    Duggan, Sarah; Cummins, Wayne; O' Donovan, Orla; Hughes, Helen; Owens, Eleanor

    2017-03-30

    Mucoadhesion is the process of binding a material to the mucosal layer of the body. Utilising both natural and synthetic polymers, mucoadhesive drug delivery is a method of controlled drug release which allows for intimate contact between the polymer and a target tissue. It has the potential to increase bioavailability, decrease potential side effects and offer protection to more sensitive drugs such as proteins and peptide based drugs. The thiolation of polymers has, in the last number of years, come to the fore of mucoadhesive drug delivery, markedly improving mucoadhesion due to the introduction of free thiol groups onto the polymer backbone while also offering a more cohesive polymeric matrix for the slower and more controlled release of drug. This review explores the concept of mucoadhesion and the recent advances in both the polymers and the methods of thiolation used in the synthesis of mucoadhesive drug delivery devices. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Gelling process of sodium alginate with bivalent ions rich microsphere: Nature of bivalent ions

    Science.gov (United States)

    Mauri, Marco; Vicini, Silvia; Castellano, Maila

    2016-05-01

    In the paper we present a new approach for obtaining a controlled gelling process of sodium alginate, based on the quantity of bivalent ions rich alginate micro-beads added as crosslinkers. Typically, calcium ions are used in gelation of alginate solutions. In this study we present different gelling systems realized with alginate microspheres, made by electrospinning methodology, enriched with different bivalent ions (Ca2+, Ba2+ and Mg2+). The microspheres were characterized under the point of view of the morphology by OM and as the ions content. Realized gels were characterized in light of the amount of the ions added to the alginate solution, and in light of the different dimensions of the micro-beads, using rheological measurements to assess the variation in the storage modulus (G'), loss modulus (G″) and complex viscosity (η*).

  8. The flow and spray characteristics of gelled fluids; Die Stroemungs- und Verspruehungseigenschaften gelfoermiger Fluide

    Energy Technology Data Exchange (ETDEWEB)

    Madlener, K.

    2008-07-01

    In the present study gelled fluids are investigated concerning their application as propellants in storable and thrust controllable rocket propulsion systems. The correlations between the non-Newtonian viscosity properties and the flow and spray characteristics are discussed. Based on the proposed viscosity model Herschel-Bulkley-Extended (HBE) the laminar pipe flow is calculated for the investigated propellants. With the introduction of a generalized form of the Reynolds number and the presentation of a possibility to determine the critical values of this number it is possible to calculate the laminar-turbulent transition in a pipe flow. The theoretical results are evaluated with experimental data. The spray characteristics of various gelled fluids are examined using an experimental setup with impinging-jet-injectors. (orig.)

  9. Study of hydroxy propyl guar derivative for its gelling property and it's use in the formulation of tenoxicam gels.

    Science.gov (United States)

    Swamy, N G N; Dharmarajan, T S; Paranjothi, K L K

    2007-01-01

    Gels of tenoxicam 1% w/w were formulated using 2% w/w hydroxy propyl guar derivative and 3% w/w sodium carboxy methyl cellulose as gelling agents. A detailed rheological investigation was carried out to study the influence of preservative, drug and preservative, solvent system and the preservative, drug, solvent system and the preservative on the pseudoplastic behaviour of polymers. Hydroxy propyl guar derivative in 2% w/w strength resulted in gels with a higher pseudoplastic index value of 3.383 in contrast to an index value of 1.797 for a 3% w/w sodium carboxy methyl cellulose gels of a similar composition. The gels were stored at different temperatures and variations in pH values were recorded. Hydroxy propyl guar derivative based gels revealed variations in pH values over a narrow range in contrast to sodium carboxy methyl cellulose gels. The gels were subjected to short term stability studies by storing gels at refrigerated temperature, lab temperature, at 37 degrees C and at 45 degrees C. Gels based on hydroxy propyl guar derivative revealed better drug keeping qualities in contrast to sodium carboxy methyl cellulose stabilized gels. Release studies of tenoxicam from formulations across hairless albino mice skin revealed a zero order drug release pattern from both the formulations.

  10. Phase Diagrams for Systems Containing Hyperbranched Polymers

    Directory of Open Access Journals (Sweden)

    Tim Zeiner

    2012-01-01

    Full Text Available Hyperbranched polymers show an outstanding potential for applications ranging from chemistry over nanotechnology to pharmacy. In order to take advantage of this potential, the underlying phase behaviour must be known. From the thermodynamic point of view, the modelling of these phase diagrams is quite challenging, because the thermodynamic properties depend on the architecture of the hyperbranched polymer as well as on the number and kind of present functional end groups. The influence of architecture can be taken into account via the lattice cluster theory (LCT as an extension of the well-known Flory–Huggins theory. Whereas the Flory–Huggins theory is limited to linear polymer chains, the LCT can be applied to an arbitrary chain architecture. The number and the kind of functional groups can be handled via the Wertheim perturbation theory, applicable for directed forces between the functional groups and the surrounding solvent molecules. The combination of the LCT and the Wertheim theory can be established for the modelling or even prediction of the liquid-liquid equilibria (LLE of polymer solutions in a single solvent or in a solvent mixture or polymer blends, where the polymer can have an arbitrary structure. The applied theory predicts large demixing regions for mixtures of linear polymers and hyperbranched polymers, as well as for mixtures made from two hyperbranched polymers. The introduction of empty lattice sites permits the theoretical investigation of pressure effects on phase behaviour. The calculated phase diagrams were compared with own experimental data or to experimental data taken from literature.

  11. Development of controlled drug release systems based on thiolated polymers.

    Science.gov (United States)

    Bernkop-Schnürch, A; Scholler, S; Biebel, R G

    2000-05-03

    The purpose of the present study was to generate mucoadhesive matrix-tablets based on thiolated polymers. Mediated by a carbodiimide, L-cysteine was thereby covalently linked to polycarbophil (PCP) and sodium carboxymethylcellulose (CMC). The resulting thiolated polymers displayed 100+/-8 and 1280+/-84 micromol thiol groups per gram, respectively (means+/-S.D.; n=6-8). In aqueous solutions these modified polymers were capable of forming inter- and/or intramolecular disulfide bonds. The velocity of this process augmented with increase of the polymer- and decrease of the proton-concentration. The oxidation proceeded more rapidly within thiolated PCP than within thiolated CMC. Due to the formation of disulfide bonds within thiol-containing polymers, the stability of matrix-tablets based on such polymers could be strongly improved. Whereas tablets based on the corresponding unmodified polymer disintegrated within 2 h, the swollen carrier matrix of thiolated CMC and PCP remained stable for 6.2 h (mean, n=4) and more than 48 h, respectively. Release studies of the model drug rifampicin demonstrated that a controlled release can be provided by thiolated polymer tablets. The combination of high stability, controlled drug release and mucoadhesive properties renders matrix-tablets based on thiolated polymers useful as novel drug delivery systems.

  12. Compositions, methods, and systems comprising fluorous-soluble polymers

    Science.gov (United States)

    Swager, Timothy M.; Lim, Jeewoo; Takeda, Yohei

    2015-10-13

    The present invention generally relates to compositions, methods, and systems comprising polymers that are fluorous-soluble and/or organize at interfaces between a fluorous phase and a non-fluorous phase. In some embodiments, emulsions or films are provided comprising a polymer. The polymers, emulsions, and films can be used in many applications, including for determining, treating, and/or imaging a condition and/or disease in a subject. The polymer may also be incorporated into various optoelectronic device such as photovoltaic cells, organic light-emitting diodes, organic field effect transistors, or the like. In some embodiments, the polymers comprise pi-conjugated backbones, and in some cases, are highly emissive.

  13. 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

  14. Applications of polymers in intraocular drug delivery systems

    Science.gov (United States)

    Alhalafi, Ali Mohammed

    2017-01-01

    We are entering a new era of ophthalmic pharmacology where new drugs are rapidly being developed for the treatment of anterior and posterior segment of the eye disease. The pharmacokinetics of drug delivery to the eye remains a very active area of ophthalmic research. Intraocular drug delivery systems allow the release of the drug, bypassing the blood-ocular barrier. The main advantage of these preparations is that they can release the drug over a long time with one single administration. These pharmaceutical systems are of great important in the treatment of the posterior segment diseases, and they can be prepared from biodegradable or nonbiodegradable polymers. Biodegradable polymers have the advantage of disappearing from the site of action after releasing the drug. The majority of intraocular devices are prepared from nonbiodegradable polymers, and they can release controlled amounts of drugs for months. Nonbiodegradable polymers include silicone, polyvinyl alcohol, and ethylene-vinyl acetate. The polymers usually employed to prepare nanoparticles for the topical ophthalmic route are poly (acrylic acid) derivatives (polyalquilcyanocrylates), albumin, poly-ε-caprolactone, and chitosan. Dendrimers are a recent class of polymeric materials with unique nanostructure which has been studied to discover their role in the delivery of therapeutics and imaging agents. Hydrogels are polymers that can swell in aqueous solvent system, and they hold the solvents in a swollen cross-linked gel for delivery. This review exhibits the current literature regarding applications of polymers in ophthalmic drug delivery systems including pharmacokinetics, advantages, disadvantages, and indications aimed to obtain successful eye therapy. Method of Literature Search: A systematic literature review was performed using PubMed databases into two steps. The first step was oriented to classification of intraocular polymers implants focusing on their advantages and disadvantages. The second

  15. Applications of polymers in intraocular drug delivery systems

    Directory of Open Access Journals (Sweden)

    Ali Mohammed Alhalafi

    2017-01-01

    Full Text Available We are entering a new era of ophthalmic pharmacology where new drugs are rapidly being developed for the treatment of anterior and posterior segment of the eye disease. The pharmacokinetics of drug delivery to the eye remains a very active area of ophthalmic research. Intraocular drug delivery systems allow the release of the drug, bypassing the blood–ocular barrier. The main advantage of these preparations is that they can release the drug over a long time with one single administration. These pharmaceutical systems are of great important in the treatment of the posterior segment diseases, and they can be prepared from biodegradable or nonbiodegradable polymers. Biodegradable polymers have the advantage of disappearing from the site of action after releasing the drug. The majority of intraocular devices are prepared from nonbiodegradable polymers, and they can release controlled amounts of drugs for months. Nonbiodegradable polymers include silicone, polyvinyl alcohol, and ethylene-vinyl acetate. The polymers usually employed to prepare nanoparticles for the topical ophthalmic route are poly (acrylic acid derivatives (polyalquilcyanocrylates, albumin, poly-μ-caprolactone, and chitosan. Dendrimers are a recent class of polymeric materials with unique nanostructure which has been studied to discover their role in the delivery of therapeutics and imaging agents. Hydrogels are polymers that can swell in aqueous solvent system, and they hold the solvents in a swollen cross-linked gel for delivery. This review exhibits the current literature regarding applications of polymers in ophthalmic drug delivery systems including pharmacokinetics, advantages, disadvantages, and indications aimed to obtain successful eye therapy. Method of Literature Search: A systematic literature review was performed using PubMed databases into two steps. The first step was oriented to classification of intraocular polymers implants focusing on their advantages and

  16. Dynamic response of a polymer and polymer composite systems: Experimental studies

    NARCIS (Netherlands)

    Fan, J.

    2015-01-01

    Recently, research on the impact resistance of transparent hybrid glass-polymer systems (layered and particle-matrix systems) has been conducted at the Netherlands Organisation for Applied Scientific Research (TNO), showing the potential of these materials for the application in protection concepts.

  17. Dynamic response of a polymer and polymer composite systems: Experimental studies

    NARCIS (Netherlands)

    Fan, J.

    2015-01-01

    Recently, research on the impact resistance of transparent hybrid glass-polymer systems (layered and particle-matrix systems) has been conducted at the Netherlands Organisation for Applied Scientific Research (TNO), showing the potential of these materials for the application in protection concepts.

  18. Polymer Matrix Composites for Propulsion Systems

    Science.gov (United States)

    Nettles, Alan T.

    2003-01-01

    The Access-to-Space study identified the requirement for lightweight structures to achieve orbit with a single-stage vehicle. Thus a task was undertaken to examine the use of polymer matrix composites for propulsion components. It was determined that the effort of this task would be to extend previous efforts with polymer matrix composite feedlines and demonstrate the feasibility of manufacturing large diameter feedlines with a complex shape and integral flanges, (i.e. all one piece with a 90 deg bend), and assess their performance under a cryogenic atmosphere.

  19. Applications of self-consistent field theory in polymer systems

    Institute of Scientific and Technical Information of China (English)

    YANG; Yuliang; QIU; Feng; TANG; Ping; ZHANG; Hongdong

    2006-01-01

    The self-consistent field theory (SCFT) based upon coarse-grained model is especially suitable for investigating thermodynamic equilibrium morphology and the phase diagram of inhomogeneous polymer systems subjected to phase separation. The advantage of this model is that the details of the chain such as the architecture of the chain and the sequence of blocks can be considered. We present here an overview of SCFT approach and its applications in polymeric systems. In particular, we wish to focus on our group's achievements in applications of SCFT in such fields: simulation of microphase separation morphologies of multiblock copolymers with a complex molecular architecture, interactions between brush-coated sheets in a polymer matrix, mixtures of flexible polymers and small molecular liquid crystals at the interface, shapes of polymer-chain-anchored fluid vesicles, self-assembled morphologies of block copolymers in dilute solution, and so on. Finally, the further developments as well as the perspective applications of SCFT are discussed.

  20. Nanoparticles as strengthening agents in polymer systems

    Science.gov (United States)

    Shahid, Naureen

    2005-11-01

    Carboxylate-substituted alumina nanoparticles are produced solvent free using mechanical shear. The general nature of this method has been demonstrated for L-lysine-, stearate, and p-hydroxybenzoate-derived materials. The reaction rate and particle size is controlled by a combination of temperature and shear rate. The nanoparticles are spectroscopically equivalent to those reported from aqueous syntheses, however, the average particle size can be decreased and the particle size distribution narrowed depending on the reaction conditions. Lysine and p-hydroxybenzoato alumoxanes have been introduced in carbon fiber reinforced epoxide resin composites. Different preparation conditions have been studied to obtain composite with enhanced performances that are ideal for the motor sports and aerospace industries. A new composite material has been fabricated utilizing surface-modified carboxylate alumoxane nanoparticles and the biodegradable polymer poly(propylene fumarate)/poly(propylene fumarate)-diacrylate (PPF/PPF-DA). For this study, composites were prepared using various functional groups including: a surfactant alumoxane to enhance nanoparticle dispersion into the polymer; an activated-alumoxane to enhance nanoparticle interaction with the polymer matrix; a mixed alumoxane containing both activated and surfactant groups. Nanocomposites prepared with all types of alumoxane, as well as blank polymer resin and unmodified boehmite, underwent mechanical testing and were characterized by SEM and microprobe analysis. A nanocomposite composed of mixed alumoxane nanoparticles dispersed in PPF/PPF-DA exhibited increased flexural modulus compared to polymer resin alone, and a significant enhancement over both the activated and surfacted alumoxanes. Boric acid is used as the cross-linking agent in oil well drilling industry even though the efficacy of the borate ion, [B(OH)4]- , as a cross-linking agent is poor. The reaction product of boric acid and the polysaccharide guaran

  1. Dynamics Research on the Gelling Course of Silica Sol

    Institute of Scientific and Technical Information of China (English)

    LUYi-chun; LIZai-geng

    1995-01-01

    Dreipping electrolytes into silica sol ,gelling reaction will occur,The research indicates:this is a complicated physicemistry course,which consists of a pre-reaction and a polymerizaion,The former controls the whole course,and in which electronic layers of the sol's particles be-come more and more thiner,but with incresing of the sol concentration,its control force will be diminished ,till the fast-coagulation ,the gelling couse becomes o-controlled,The latter is an in-finite polymeric chani-reaction.The result of gelatination is to produce a very big plymeric molecule-gel,which involves in all space,includes all water ,and its molecular weight is in-definite big.The researh also indicates:the dy-namic course of the gelling could be described quantitaively by an experience formula:lgt=-nlgc+B,All of the characteristic values have definite physical meaning,Electronic value of the contrary-inos is the biggest influential factor ,the natures of the contrary-ions and the natures of the same-electronic-inos have a few influential forces on the characteristic values,The temperature increasing makes the gelling reaction fast.

  2. A molecular dynamics study of polymer/graphene interfacial systems

    Energy Technology Data Exchange (ETDEWEB)

    Rissanou, Anastassia N.; Harmandaris, Vagelis [Department of Mathematics and Applied Mathematics, University of Crete, GR-71409, Heraklion, Crete, Greece and Institute of Applied and Computational Mathematics (IACM), Foundation for Research and Technology Hellas (FORTH), GR-71110, Heraklion, Cret (Greece)

    2014-05-15

    Graphene based polymer nanocomposites are hybrid materials with a very broad range of technological applications. In this work, we study three hybrid polymer/graphene interfacial systems (polystyrene/graphene, poly(methyl methacrylate)/graphene and polyethylene/graphene) through detailed atomistic molecular dynamics (MD) simulations. Density profiles, structural characteristics and mobility aspects are being examined at the molecular level for all model systems. In addition, we compare the properties of the hybrid systems to the properties of the corresponding bulk ones, as well as to theoretical predictions.

  3. Alternative High Performance Polymers for Ablative Thermal Protection Systems

    Science.gov (United States)

    Boghozian, Tane; Stackpoole, Mairead; Gonzales, Greg

    2015-01-01

    Ablative thermal protection systems are commonly used as protection from the intense heat during re-entry of a space vehicle and have been used successfully on many missions including Stardust and Mars Science Laboratory both of which used PICA - a phenolic based ablator. Historically, phenolic resin has served as the ablative polymer for many TPS systems. However, it has limitations in both processing and properties such as char yield, glass transition temperature and char stability. Therefore alternative high performance polymers are being considered including cyanate ester resin, polyimide, and polybenzoxazine. Thermal and mechanical properties of these resin systems were characterized and compared with phenolic resin.

  4. Recent Trends of Polymer Mediated Liposomal Gene Delivery System

    Directory of Open Access Journals (Sweden)

    Shyamal Kumar Kundu

    2014-01-01

    Full Text Available Advancement in the gene delivery system have resulted in clinical successes in gene therapy for patients with several genetic diseases, such as immunodeficiency diseases, X-linked adrenoleukodystrophy (X-ALD blindness, thalassemia, and many more. Among various delivery systems, liposomal mediated gene delivery route is offering great promises for gene therapy. This review is an attempt to depict a portrait about the polymer based liposomal gene delivery systems and their future applications. Herein, we have discussed in detail the characteristics of liposome, importance of polymer for liposome formulation, gene delivery, and future direction of liposome based gene delivery as a whole.

  5. Aerosol assisted depositions of polymers using an atomiser delivery system.

    Science.gov (United States)

    Crick, Colin R; Clausen-Thue, Victoria; Parkin, Ivan P

    2011-09-01

    The hydrophobicity, robustness and anti-microbial properties of Sylgard 184 polymer films deposited via AACVD were optimised by using aerosol droplets from an atomiser delivery system, polymer coating substrates and the swell encapsulation of methylene blue. By using an atomiser deposition system (average droplet size 0.35 microm) rather than a misting aerosol system (45 microm) lead to a surface with smaller surface features, which improved hydrophobicity (water contact angle 165 degrees) in addition to increasing the films transparency from ca 10 to 65%. Pre-treating the substrates with the same Sylgard 184 elastomer lead to a highly consistent surface hydrophobicity and an increase in average water contact angle measured (169 degrees). This paper shows the first example of dye incorporation in a CVD derived polymer film-these films have potential as antimicrobial surfaces.

  6. Nonlinear Response of Strong Nonlinear System Arisen in Polymer Cushion

    Directory of Open Access Journals (Sweden)

    Jun Wang

    2013-01-01

    Full Text Available A dynamic model is proposed for a polymer foam-based nonlinear cushioning system. An accurate analytical solution for the nonlinear free vibration of the system is derived by applying He's variational iteration method, and conditions for resonance are obtained, which should be avoided in the cushioning design.

  7. Characterization of ionic, dipolar and molecular mobility in polymer systems

    Science.gov (United States)

    Guo, Zhenrong

    Changes in the ionic and dipolar molecular mobility in a polymer system are the basis for the changes in the dielectric mechanical properties of polymer materials. Frequency Dependent Dielectric Measurements (FDEMS) and Ion Time-of-Flight (ITOF) are two important techniques to investigate ionic and dipolar molecular mobility in polymer systems. The results can be related to the macro- and molecular dielectric, electrical and dynamic properties of polymeric materials. The combination of these two methods provides a full view of electric, dielectric and dynamic behavior for the systems as they undergo chemical and/or physical changes during polymerization crystallization, vitrification, and/or phase separation. The research on microscopic mass mobility in polymer systems was done on three aspects: (1) ion mobility in an epoxy-amine reaction system; (2) dipolar mobility and relaxation during dimethacrylate resin cure and (3) dye molecule migration and diffusion in polymer films. In the ion mobility study, we separately monitor the changes in the ion mobility and the number of charge carriers during the epoxy-amine polymerization with FDEMS and ITOF measurements. The isolation of the number of carriers and their mobility allows significant improvement in monitoring changes in the state and structure of a material as it cures. For the dipolar mobility and relaxation study, FDEMS measurements were used to detect structural evolution and spatial heterogeneity formation during the polymerization process of dimethacrylate resins. The dielectric spectra, glass transition (Tg) profiles and dynamic mechanical measurements were used to investigate the existence of two cooperative regions of sufficient size to create two alpha-relaxation processes representing oligomer rich and polymer microgel regions during the polymerization. For the dye migration research, we tried to develop a visually color changing paper (VCP) due to dye molecule migration in polymer films. The mobility

  8. Interpenetrating Polymer Networks as Innovative Drug Delivery Systems

    Directory of Open Access Journals (Sweden)

    Alka Lohani

    2014-01-01

    Full Text Available Polymers have always been valuable excipients in conventional dosage forms, also have shown excellent performance into the parenteral arena, and are now capable of offering advanced and sophisticated functions such as controlled drug release and drug targeting. Advances in polymer science have led to the development of several novel drug delivery systems. Interpenetrating polymer networks (IPNs have shown superior performances over the conventional individual polymers and, consequently, the ranges of applications have grown rapidly for such class of materials. The advanced properties of IPNs like swelling capacity, stability, biocompatibility, nontoxicity and biodegradability have attracted considerable attention in pharmaceutical field especially in delivering bioactive molecules to the target site. In the past few years various research reports on the IPN based delivery systems showed that these carriers have emerged as a novel carrier in controlled drug delivery. The present review encompasses IPNs, their types, method of synthesis, factors which affects the morphology of IPNs, extensively studied IPN based drug delivery systems, and some natural polymers widely used for IPNs.

  9. DIFFUSION COEFFICIENTS IN POLYMER-SOLVENT SYSTEMS FOR HIGHLY CONCENTRATED POLYMER SOLUTIONS

    Directory of Open Access Journals (Sweden)

    R.A. Reis

    2001-12-01

    Full Text Available The Vrentas/Duda proposal for the diffusion of polymer-solvent systems, which is based on the free-volume theory, was employed in correlating and predicting mutual diffusion coefficients in highly concentrated polymer solutions. It has been observed that the predictive version of the model is capable of qualitatively representing the experimental data, while the use of an adjustable parameter greatly improves the performance of the model. The systems studied were poly(vinyl acetate-toluene and Neoprene-acetone, and a comparison between experimental data and calculated values from the Vrentas/Duda model is reported. A new experimental apparatus based on the sorption technique was built to provide reliable diffusivity data on the Neoprene-acetone system.

  10. Phases of polymer systems in solution studied via molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Joshua Allen [Iowa State Univ., Ames, IA (United States)

    2009-05-01

    Polymers are amazingly versatile molecules with a tremendous range of applications. Our lives would be very different without them. There would be no multitudes of plastic encased electronic gizmos, no latex paint on the walls and no rubber tires, just to name a few of the many commonplace polymer materials. In fact, life as we know it wouldn’t exist without polymers as two of the most essential types of molecules central to cellular life, Proteins and DNA, are both polymers! [1] With their wide range of application to a variety of uses, polymers are still a very active field in basic research. Of particular current interest is the idea of combining polymers with inorganic particles to form novel composite materials. [2] As computers are becoming faster, they are becoming all the more powerful tools for modeling and simulating real systems. With recent advances in computing on graphics processing units (GPUs) [3–7], questions can now be answered via simulation that could not even be asked before. This thesis focuses on the use of computer simulations to model novel polymerinorganic composite systems in order to predict what possible phases can form and under what conditions. The goal is to provide some direction for future experiments and to gain a deeper understanding of the fundamental physics involved. Along the way, there are some interesting and essential side-tracks in the areas of equilibrating complicated phases and accelerating the available computer power with GPU computing, both of which are necessary steps to enable the study of polymer nanocomposites.

  11. Experimental comparative study of doublet and triplet impinging atomization of gelled fuel based on PIV

    Science.gov (United States)

    Yang, Jian-lu; Li, Ning; Weng, Chun-sheng

    2016-10-01

    Gelled propellant is promising for future aerospace application because of its combination of the advantages of solid propellants and liquid propellants. An effort was made to reveal the atomization properties of gelled fuel by particle image velocimetry (PIV) system. The gelled fuel which was formed by gasoline and Nano-silica was atomized using a like-doublet impingement injector and an axisymmetric like-triplet impingement injector. The orifice diameter and length of the nozzle used in this work were of 0.8mm, 4.8mm, respectively. In the impinging spray process, the impingement angles were set at 90° and 120°, and the injection pressures were of 0.50MPa and 1.00MPa. The distance from the exit of the orifice to the impingement point was fixed at 9.6mm. In this study, high-speed visualization and temporal resolution particle image velocimetry techniques were employed to investigate the impingement atomization characteristics. The experimental investigation demonstrated that a long narrow high speed droplets belt formed around the axis of symmetry in the like-doublet impinging atomization area. However, there was no obvious high-speed belt with impingement angle 2θ = 90° and two high-speed belts appeared with impingement angle 2θ = 120° in the like-doublet impingement spray field. The high droplet velocity zone of the like-doublet impingement atomization symmetrically distributed around the central axis, and that of the like-triplet impingement spray deflected to the left of the central axis - opposite of injector. Although the droplets velocity distribution was asymmetry of like-triplet impingement atomization, the injectors were arranged like axisymmetric conical shape, and the cross section of spray area was similar to a circle rather than a narrow rectangle like the like-doublet impingement atomization.

  12. In situ gelling, bioadhesive nasal inserts for extended drug delivery: in vitro characterization of a new nasal dosage form.

    Science.gov (United States)

    Bertram, Ulrike; Bodmeier, Roland

    2006-01-01

    The purpose of this study was the preparation and characterization of sponge-like, in situ gelling inserts based on bioadhesive polymers. Hydrophilic polymers (carrageenan, Carbopol, chitosan, hydroxypropyl methylcellulose (HPMC) K15M and E5, sodium alginate, sodium carboxy methylcellulose (NaCMC), polyvinyl pyrrolidone (PVP) 90, xanthan gum) were dissolved with/without the model drug oxymetazoline HCl in demineralized water and lyophilized into small inserts. The drug release, water uptake, mechanical properties, X-ray diffraction and bioadhesion potential of the nasal inserts were investigated. A sponge-like structure of nasal inserts was formed with amorphous, but not with crystalline polymers during the freeze-drying process. The insert hardness increased with the glass transition temperature of the polymer (PVP25HPMC E5, Na-alginate, PVP90). The drug release from inserts prepared from high molecular weight polymers (carrageenan, Carbopol, chitosan, HPMC K15M, NaCMC, xanthan gum) was a complex interplay of osmotic forces, water uptake and electrostatic interactions between drug and polymer. The drug release decreased with higher polymer content and increased drug loading of the insert. Bioadhesive nasal inserts have a high potential as new nasal dosage form for extended drug delivery.

  13. Hybrid energy harvesting systems, using piezoelectric elements and dielectric polymers

    Science.gov (United States)

    Cornogolub, Alexandru; Cottinet, Pierre-Jean; Petit, Lionel

    2016-09-01

    Interest in energy harvesting applications has increased a lot during recent years. This is especially true for systems using electroactive materials like dielectric polymers or piezoelectric materials. Unfortunately, these materials despite multiple advantages, present some important drawbacks. For example, many dielectric polymers demonstrated high energy densities; they are cheap, easy to process and can be easily integrated in many different structures. But at the same time, dielectric polymer generators require an external energy supply which could greatly compromise their autonomy. Piezoelectric systems, on the other hand, are completely autonomous and can be easily miniaturized. However, most common piezoelectric materials present a high rigidity and are brittle by nature and therefore their integration could be difficult. This paper investigates the possibility of using hybrid systems combining piezoelectric elements and dielectric polymers for mechanical energy harvesting applications and it is focused mainly on the problem of electrical energy transfer. Our objective is to show that such systems can be interesting and that it is possible to benefit from the advantages of both materials. For this, different configurations were considered and the problem of their optimization was addressed. The experimental work enabled us to prove the concept and identify the main practical limitations.

  14. 一种胶体电解液胶凝时间的测定方法%The method measuring the gelling time of gelled electrolyte

    Institute of Scientific and Technical Information of China (English)

    代少振; 王亚斌; 徐丹; 万南红; 刘孝伟

    2015-01-01

    The turbidimetry method measuring the gelling time of gelled electrolyte has been established in this paper. The gelling time of gelled electrolyte can be measured simply, intuitively and accurately by this method, which provides the support of experimental method for development of gelled lead-acid battery.%本文建立了浊度法测定胶体电解液胶凝时间的方法。该方法能简便、直观、准确地测定胶体电解液的胶凝时间,为胶体电池的电解液研制提供实验方法支持。

  15. The agency of Gell in the anthropology of art

    Directory of Open Access Journals (Sweden)

    Caleb Faria Alves

    2008-01-01

    Full Text Available While delineating the parameters for an anthropology of art, Alfred Gell's famous book, Art and Agency, overlooked, for the most part, anthropological tradition. This raises questions as embarrassing as they are ignored: is it possible to produce good theory with no references to achieved knowledge in this particular field? Are the subjects within anthropology so differently pursued that it is not possible to refer to a common way of approaching them? What exactly do we lose with such a self-centered narrative? My point of view is that theory cannot be treated like a list of sentences that can be added to one another, according to their isolated importance. This article proposes an analysis of Alfred Gell's narrative, of how he connects its propositions. I will examine, overall, his readings, the authors he quotes like Peirce, Sally Price and others, and how he fits them along his argumentation. The objective of this exercise is to put in evidence, beyond Gell's definitions, some conceptions about art contained in his formulations, and to enlarge the range of potential references available for an anthropology of art.

  16. Printed polymer photonic devices for optical interconnect systems

    Science.gov (United States)

    Subbaraman, Harish; Pan, Zeyu; Zhang, Cheng; Li, Qiaochu; Guo, L. J.; Chen, Ray T.

    2016-03-01

    Polymer photonic device fabrication usually relies on the utilization of clean-room processes, including photolithography, e-beam lithography, reactive ion etching (RIE) and lift-off methods etc, which are expensive and are limited to areas as large as a wafer. Utilizing a novel and a scalable printing process involving ink-jet printing and imprinting, we have fabricated polymer based photonic interconnect components, such as electro-optic polymer based modulators and ring resonator switches, and thermo-optic polymer switch based delay networks and demonstrated their operation. Specifically, a modulator operating at 15MHz and a 2-bit delay network providing up to 35.4ps are presented. In this paper, we also discuss the manufacturing challenges that need to be overcome in order to make roll-to-roll manufacturing practically viable. We discuss a few manufacturing challenges, such as inspection and quality control, registration, and web control, that need to be overcome in order to realize true implementation of roll-to-roll manufacturing of flexible polymer photonic systems. We have overcome these challenges, and currently utilizing our inhouse developed hardware and software tools, communication, sensing, medicine, security, imaging, energy, lighting etc.

  17. Light scattering from macromolecular systems: Molecular crystals and polymers

    Science.gov (United States)

    Bernstein, E. R.

    1981-11-01

    The research objectives were to: (1) characterize phase transitions theoretically and experimentally in molecular crystal systems; (2) use the above understanding gained by light scattering studies and theoretical interpretation to apply to the more complex system of lyotropic liquid crystals; and (3) then apply knowledge gained on the model systems of increasing complexity to polymer liquid crystals and solid polymers as observed by laser light scattering techniques. Systems experimentally and theoretically discussed are: trioxane, triazine, benzil, and chloranil. Studies of lyotropic liquid crystals (sodium decyl sulfate, sodium sulfate, decanol, water) have progressed. The major findings are: a number of phase transitions occur between 20 and 60 C; these transitions evidence strong critical behavior and long correlation times for fluctuations; and liquid crystals can be studied by light scattering. Spectra of solid powders, ribbons, and liquid crystals of PBT and solid PBO were obtained.

  18. Modeling of rheological properties for entangled polymer systems

    Science.gov (United States)

    Banerjee, Nilanjana

    The study of entangled polymer rheology both in the field of medicine and polymer processing has their major importance. Mechanical properties of biomolecules are studied in order to better understand cellular behavior. Similarly, industrial processing of polymers needs thorough understanding of rheology so as to improve process techniques. Work in this dissertation has been organized into three major sections. Firstly, numerical/analytical models are reviewed for describing rheological properties and mechanical behaviors of cytoskeleton. The cytoskeleton models are classified into categories according to the length scales of the phenomena of interest. The main principles and characteristics of each model are summarized and discussed by comparison with each other, thus providing a systematic understanding of biopolymer network modeling. Secondly, a new constitutive "toy" Mead-Banerjee-Park (MBP) model is developed for monodisperse entangled polymer systems, by introducing the idea of a configuration dependent friction coefficient (CDFC) and entanglement dynamics (ED) into the MLD "toy" model. The model is tested against experimental data in steady and transient extensional and shear flows. The model simultaneously captures the monotonic thinning of the extensional flow curve of polystyrene (PS) melts and the extension hardening found in PS solutions. Thirdly, the monodisperse MBP model is accordingly modified into polydisperse MBP "toy" constitutive model to predict the nonlinear viscoelastic material properties of model polydisperse systems. The polydisperse MBP toy model accurately predicts the material properties in the forward direction for transient uniaxial extension and transient shear flow.

  19. Use of olive oil-in-water gelled emulsions in model turkey breast emulsions

    Science.gov (United States)

    Serdaroğlu, M.; Öztürk, B.

    2017-09-01

    Today, gelled emulsion systems offer a novel possibility in lipid modification of meat products. In this study, we aimed to investigate the quality characteristics of model turkey emulsions that were prepared with olive oil-in-water gelled emulsion (GE) as partial or total beef fat replacer. The results indicated that while most of the GE treatments showed equivalent emulsion characteristics in terms of emulsion stability, water-holding capacity and cook yield, utilization of 100% GE as the lipid source could increase total expressible fluid of the model turkey emulsion and thus negatively affect the quality. Utilization of GE was effective in total fat reduction, as the model turkey emulsions formulated with more than 50% GE had significantly lower fat content compared to full-beef fat control model emulsion. However, beef fat replacement with GE produced considerable changes in colour parameters. Finally, it was concluded that utilization of GE as a partial beef fat replacer has good potential to enhance stability and reduce total fat in turkey meat emulsion products.

  20. Effect of attractive interactions between polymers on the effective force acting between colloids immersed in a polymer system: Analytic liquid-state theory.

    Science.gov (United States)

    Chervanyov, A I

    2016-12-28

    By making use of the polymer reference interaction site model, we analytically study the effect of attractive interactions between polymers on the effective forces acting between colloids immersed in a polymer system. The performed theoretical analysis has no restrictions with respect to the polymer density and relative sizes of the colloids and polymers. The polymer mediated (PM) potential acting between colloids is shown to significantly depend on the strength and range of the polymer-polymer interactions. In the nano-particle limit, where the colloid radius is much smaller than the polymer gyration radius, the presence of attractive polymer-polymer interactions causes only quantitative changes to the PM potential. In the opposite limit of relatively large colloids, the polymer-polymer interactions revert the sign of the total effective force acting between colloids so that this force becomes attractive at sufficiently large polymer densities. With the objective to study an intricate interplay between the attractive PM forces and steric repulsion in different polymer density regimes, we calculate the second virial coefficient B of the total effective potential acting between colloids. The dependence of B on the polymer density is discussed in detail, revealing several novel features of the PM interactions caused by the presence of attractive polymer-polymer interactions.

  1. Polymer waveguide systems for nonlinear and electro-optic applications

    Science.gov (United States)

    Pantelis, Philip; Hill, Julian R.; Kashyap, Raman

    1991-12-01

    Waveguides with photochromic or electro-optic properties have been fabricated by a new technique using spin coating of polymers, or guest/host-polymer systems, on to grooves etched in an indium phosphide wafer. Monomoded waveguides at 633 nm, and at 1320 and 1550 nm (wavelengths of telecommunications interest) have been fabricated. These guides have good quality cleaved ends which allow efficient coupling of light from monomoded standard lensed silica fibers. An example of an electro-optic application is given in the form of a phase modulator. This device uses a side-chain polymer as the waveguide core that develops linear electro-optic properties following an electric field alignment process. It was found to have a switching voltage of 30 V, for a (pi) phase change, and had a total insertion loss of 9.4 dB. Waveguides with photochromic properties have also been produced using Aberchrome 670 (a commercially available fulgide) as a guest in a poly(methyl methacrylate) polymer host. Refractive index, optical loss, photochromic activity, and film forming properties of differing concentrations of guest (up to 20% concentration by weight) have been measured and are reported.

  2. Oral pulsatile delivery systems based on swellable hydrophilic polymers.

    Science.gov (United States)

    Gazzaniga, Andrea; Palugan, Luca; Foppoli, Anastasia; Sangalli, Maria Edvige

    2008-01-01

    Upon contact with aqueous fluids, swellable hydrophilic polymers undergo typical chain relaxation phenomena that coincide with a glassy-rubbery transition. In the rubbery phase, these polymers may be subject to swelling, dissolution and erosion processes or, alternatively, form an enduring gel barrier when cross-linked networks (hydrogels) are dealt with. Because of the peculiar hydration and biocompatibility properties, such materials are widely exploited in the pharmaceutical field, particularly as far as hydrophilic cellulose derivatives are concerned. In oral delivery, they have for long been employed in the manufacturing of prolonged release matrices and, more recently, for pulsatile (delayed) release devices as well. Pulsatile delivery, which is meant as the liberation of drugs following programmed lag phases, has drawn increasing interest especially in view of emerging chronotherapeutic approaches. In pursuit of pulsatile release, various design strategies have been proposed, chiefly including reservoir, capsular and osmotic formulations. In most cases, water-swellable polymers play a key role in the overall delivery mechanism after being activated by physiological media. Based on these premises, the aim of the present review is to survey the main oral pulsatile delivery systems, for which swelling, dissolution and/or erosion of hydrophilic polymers are primarily involved in the control of release.

  3. Multifunctional non-viral delivery systems based on conjugated polymers.

    Science.gov (United States)

    Yang, Gaomai; Lv, Fengting; Wang, Bing; Liu, Libing; Yang, Qiong; Wang, Shu

    2012-12-01

    Multifunctional nanomaterials with simultaneous therapeutic and imaging functions explore new strategies for the treatment of various diseases. Conjugated polymers (CPs) are considered as novel candidates to serve as multifunctional delivery systems due to their high fluorescence quantum yield, good photostability, and low cytotoxicity. Highly sensitive sensing and imaging properties of CPs are well reviewed, while the applications of CPs as delivery systems are rarely covered. This feature article mainly focuses on CP-based multifunctional non-viral delivery systems for drug, protein, gene, and cell delivery. Promising directions for the further development of CP-based delivery systems are also discussed.

  4. One-step polymer surface modification for minimizing drug, protein, and DNA adsorption in microanalytical systems

    DEFF Research Database (Denmark)

    Larsen, Esben Kjær Unmack; Larsen, Niels Bent

    2013-01-01

    The non-specific adsorption of dissolved analytes strongly reduces the sensitivity and reliability in polymer microanalytical systems. Here, a one-step aqueous phase procedure modifies polymer material surfaces to strongly reduce their non-specific adsorption of a broad range of organic analytes ...... systems, including polystyrene (PS), cyclic olefin copolymer (COC), liquid crystalline polymer (LCP), and polyimide (PI)....

  5. Polymers for Pharmaceutical Packaging and Delivery Systems

    DEFF Research Database (Denmark)

    Fristrup, Charlotte Juel

    -bromoisobutyrate initiating sites. Each modification step of PEEK as well as grafting of poly(ethylene glycol) methacrylate (PEGMA) was followed and confirmed by Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy, water contact angle (WCA) measurements, and Thermal Gravimetric Analysis....... X-ray Photoelectron Spectroscopy also confirmed the presence of the poly(PEGMA) grafts on the PEEK surface by comparing the C/O ratio and the chemical composition after each modification step. The surface topography was evaluated by Atomic Force Microscopy. Polypropylene (PP) is one of the polymeric...... materials of interest for pharmaceutical packaging and delivery systems. Confocal fluorescence microscopy studies and stability studies with insulin aspart (AspB28 insulin) were conducted to evaluate the impact of modified PP compared to unmodified PP. In contrast to PEEK, PP did not contain any functional...

  6. Viscosity of the oil-in-water Pickering emulsion stabilized by surfactant-polymer and nanoparticle-surfactant-polymer system

    Science.gov (United States)

    Sharma, Tushar; Kumar, G. Suresh; Chon, Bo Hyun; Sangwai, Jitendra S.

    2014-11-01

    Information on the viscosity of Pickering emulsion is required for their successful application in upstream oil and gas industry to understand their stability at extreme environment. In this work, a novel formulation of oil-in-water (o/w) Pickering emulsion stabilized using nanoparticle-surfactant-polymer (polyacrylamide) system as formulated in our earlier work (Sharma et al., Journal of Industrial and Engineering Chemistry, 2014) is investigated for rheological stability at high pressure and high temperature (HPHT) conditions using a controlled-strain rheometer. The nanoparticle (SiO2 and clay) concentration is varied from 1.0 to 5.0 wt%. The results are compared with the rheological behavior of simple o/w emulsion stabilized by surfactant-polymer system. Both the emulsions exhibit non-Newtonian shear thinning behavior. A positive shift in this behavior is observed for surfactant-polymer stabilized emulsion at high pressure conditions. Yield stress is observed to increase with pressure for surfactant-polymer emulsion. In addition, increase in temperature has an adverse effect on the viscosity of emulsion stabilized by surfactant-polymer system. In case of nanoparticle-surfactant-polymer stabilized o/w emulsion system, the viscosity and yield stress are predominantly constant for varying pressure and temperature conditions. The viscosity data for both o/w emulsion systems are fitted by the Herschel-Bulkley model and found to be satisfactory. In general, the study indicates that the Pickering emulsion stabilized by nanoparticle-surfactant-polymer system shows improved and stable rheological properties as compared to conventional emulsion stabilized by surfactant-polymer system indicating their successful application for HPHT environment in upstream oil and gas industry.

  7. Processing of Polymer Nanofibers Through Electrospinning as Drug Delivery Systems

    Science.gov (United States)

    Kenawy, E.; Abdel-Hay, F. I.; El-Newehy, M. H.; Wnek, G. E.

    The use of electrospun fibers as drug carriers could be promising in the future for biomedical applications, especially postoperative local chemotherapy. In this research, electrospun fibers were developed as a new system for the delivery of ketoprofen as non-steroidal anti-inflammatory drug (NSAID). The fibers were made either from polycaprolactone (PCL) as a biodegradable polymer or polyurethane (PU) as a non-biodegradable polymer, or from the blends of the two. The release of the ketoprofen was followed by UV—VIS spectroscopy in phosphate buffer of pH 7.4 at 37°C and 20°C. The results showed that the release rates from the polycaprolactone, polyurethane and their blend were similar. However, the blend of the polycaprolactone with polyurethane improved its visual mechanical properties. Release profiles from the electrospun mats were compared to cast films of the various formulations.

  8. A agência de Gell na antropologia da arte

    Directory of Open Access Journals (Sweden)

    Caleb Faria Alves

    2008-06-01

    Full Text Available Ao delinear os parâmetros para uma antropologia da arte, o famigerado livro de Alfred Gell, Art and Agency, deixou de lado boa parte da antropologia, o que coloca algumas questões tão embaraçosas quanto pouco tratadas: pode-se fazer boa teoria sem contar com o acúmulo de conhecimento nessa área? Ou os temas recebem tratamento tão díspar que realmente não faz sentido falar mais em princípios teóricos comuns que podem e devem ser aplicados a qualquer objeto? O que perdemos com uma narrativa tão autocentrada? Partindo do pressuposto de que não é possível tratar teoria enquanto um conjunto de máximas que se somam ou se substituem, ou como um tabuleiro de peças que se acomodam umas às outras segundo sua validade isolada, este artigo procede a um exame da narrativa contida no livro de Gell, das articulações que realiza entre suas proposições. Examinarei, sobretudo, a leitura que faz dos autores que cita, como Peirce, Sally Price, e outros, e como os encaixa na sua argumentação. O objetivo desse exercício é evidenciar, para além de suas próprias definições, certas concepções sobre arte contidas na abordagem que Gell sugere e ampliar as referências para uma antropologia da arte.While delineating the parameters for anthropology of art, the famous Alfred Gell's book, Art and Agency, left apart most of the anthropology authors, what arises some embarrassing and rarely dealt with questions: is it possible to produce good theory with no references to achieved knowledge in this particular field? The subjects within anthropology are so differently undertaken that doesn't make any sense to refer to common ways of approaching them? What exactly we loose which a narrative so self centered? Is my point of view that theory cannot be treated like a list of sentences that can be added to one another according to its isolated importance. This article proposes an analysis of Alfred Gell's narrative, of how he connects its propositions

  9. Progress in the development of gelling agents for improved culturability of microorganisms

    Directory of Open Access Journals (Sweden)

    Nabajit eDas

    2015-07-01

    Full Text Available Gelling agents are required for formulating both solid and semisolid media, vital for the isolation of microorganisms. Gelatin was the first gelling agent to be discovered but it soon paved the way for agar, which has far superior material qualities. Source depletion, issues with polymerase-chain-reaction and inability to sustain extermophiles etc., necessitate the need of other gelling agents. Many new gelling agents, such as xantham gum, gellan gum, carrageenan, isubgol and guar gum have been formulated, raising the hopes for the growth of previously unculturable microorganisms. We evaluate the progress in the development of gelling agents, with the hope that our synthesis would help accelerate research in the field.

  10. Ferritin nanocontainers that self-direct in synthetic polymer systems

    Science.gov (United States)

    Sengonul, Merih C.

    Currently, there are many approaches to introduce functionality into synthetic polymers. Among these, for example, are copolymerization, grafting, and blending methods. However, modifications made by such methods also change the thermodynamics and rheological properties of the polymer system of interest, and each new modification often requires a costly reoptimization of polymer processing. Such a reoptimalization would not be necessary if new functionality could be introduced via a container whose external surface is chemically and physically tuned to interact with the parent polymer. The contents of the container could then be changed without changing other important properties of the parent polymer. In this context this thesis project explores an innovative nanocontainer platform which can be introduced into phase-separating homopolymer blends. Ferritin is a naturally existing nanocontainer that can be used synthetically to package and selectively transport functional moieties to a particular phase that is either in the bulk or on the surface of a homopolymer blend system. The principal focus of this work centers on modifying the surface of wild ferritin to: (1) render modified ferritin soluble in a non-aqueous solvent; and (2) impart it with self-directing properties when exposed to a homopolymer blend surface or incorporated into the bulk of a homopolymer blend. Wild ferritin is water soluble, and this research project successfully modified wild ferritin by grafting either amine-functional poly(ethylene glycol) (PEG) or short-chain alkanes to carbodiimide activated carboxylate groups on ferritin's surface. Such modified ferritin is soluble in dichloromethane (DCM). Modification was confirmed by ion-exchange chromatography, zeta-potential measurements, and electrospray mass spectroscopy. FT-IR was used to quantify the extent of PEGylation of the reaction products through area ratios of the -C-O-C asymmetric stretching vibration of the grafted PEG chains to the

  11. Selected gelling agents in canned dog food affect nutrient digestibilities and fecal characteristics of ileal cannulated dogs

    NARCIS (Netherlands)

    Karr-Lilienthal, L.K.; Merchen, N.R.; Grieshop, C.M.; Smeets-Petersen, M.J.E.; Fahey, G.C.

    2002-01-01

    Little is known about the effects of gelling agents in canned dog food on nutrient digestibilities and fecal characteristics. Dogs were fed canned diets with either no gelling agent (control) or one of three gelling agents, wheat starch, a guar gum/carrageenan mixture (50:50), and a locust bean meal

  12. Integrated polymer waveguides for absorbance detection in chemical analysis systems

    DEFF Research Database (Denmark)

    Mogensen, Klaus Bo; El-Ali, Jamil; Wolff, Anders

    2003-01-01

    . The emphasis of this paper is on the signal-to-noise ratio of the detection and its relation to the sensitivity. Two absorbance cells with an optical path length of 100 μm and 1000 μm were characterized and compared in terms of sensitivity, limit of detection and effective path length for measurements......A chemical analysis system for absorbance detection with integrated polymer waveguides is reported for the first time. The fabrication procedure relies on structuring of a single layer of the photoresist SU-8, so both the microfluidic channel network and the optical components, which include planar...

  13. From Gelation and Glass Transition of Colloidal Systems to Polymers

    Science.gov (United States)

    Han, Charles; Yuan, Guangcui; Cheng, He

    Charles C. Han, Guangcui Yuan and He Cheng Joint Laboratory of Polymer Science and Materials, ICCAS, Beijing, China and Institute for Advanced Study, Shenzhen University, Shenzhen, China Aggregation and gelation behavior of mixed suspensions of polystyrene microspheres and poly(N-isopropylacrylamide) microgels have been studied. In dilute microsphere suspensions, with increasing concentration of microgel (MG), microspheres (MS) first aggregated with each other through the bridging of the microgels, then dispersed individually when saturated adsorption was achieved, and finally depletion clusters formed at even higher concentrations of microgel. In concentrated microsphere suspensions, with saturated MG adsorption, a state transition from attractive glass to repulsive glass can be observed. This type of system can be viewed as a molecular model system which has a long range repulsive interaction potential and a short range attractive potential. A comparison between the glass transition of the colloidal systems and the glass transition of polymeric systems can be made.

  14. Anisotropy in Thermo-Optic Coefficient of Different Polymer Systems by Attenuated Total Reflection Configuration

    Institute of Scientific and Technical Information of China (English)

    LI Xiang; CAO Zhuang-Qi; SHEN Qi-Shun; MENG Qing-Hua; HUANG De-Ying; GUO Kun-Peng; QIU Ling; SHEN Yu-Quan

    2006-01-01

    @@ Thermo-optic coefficient dn/dT as well as volume expansion coefficients β of different polymer systems are measured for both TE and TM polarizations in an attenuated total reflection (ATR) configuration. Experimental results indicate that cross-linked polymer systems exhibit the thermal expansion coefficients smaller than those of the original side-chain systems. Moreover, the anisotropies in thermo-optic coefficients of the polymer systems with small birefringence exhibit linear relationship with the anisotropies in volume expansion coefficients, but the polymer systems with larger birefringence exhibit more complicated relationship.

  15. Polymer biomaterial constructs for regenerative medicine and functional biological systems

    Science.gov (United States)

    Meng, Linghui

    The use of collagen as a biomaterial is currently undergoing a renaissance in the tissue engineering field. The excellent biocompatibility and safety due to its biological characteristics, such as biodegradability and weak antigenicity, make collagen a primary material resource in medical applications. Described herein is work towards the development of novel collagen-based matrices, with additional multi-functionality imparted through a novel in-situ crosslinking approach. The process of electrospinning has become a widely used technique for the creation of fibrous scaffolds for tissue engineering applications due to its ability to rapidly create structures composed of nano-scale polymer fibers closely resembling the architecture of the extracellular matrix (ECM). Collagen-PCL sheath-core bicomponent fibrous scaffolds were fabricated using a novel variation on traditional electrospinning, known as co-axial electrospinning. The results showed that the addition of a synthetic polymer core into collagen nanofibers remarkably increased the mechanical strength of collagen matrices spun from the benign solvent system. A novel single-step, in-situ collagen crosslink approach was developed in order to solve the problems dominating traditional collagen crosslinking methods, such as dimensional shrinking and loss of porous morphology, and to simplify the crosslinking procedure for electrospun collagen scaffolds. The excess amount of NHS present in the crosslinking mixture was found to delay the EDC/collagen coupling reaction in a controlled fashion. Fundamental investigations into the development and characterization of in-situ crosslinked collagen matrices such as fibrous scaffolds, gels and sponges, as well as their biomedical applications including cell culture substrates, wound dressings, drug delivery matrices and bone regeneration substitutes, were performed. The preliminary mice studies indicated that the in-situ crosslinked collagen matrices could be good candidates

  16. Smart polymers in nasal drug delivery

    Directory of Open Access Journals (Sweden)

    Ankita Chonkar

    2015-01-01

    Full Text Available Nasal drug delivery has now been recognized as a promising route for drug delivery due to its capability of transporting a drug to systemic circulation and central nervous system. Though nasal mucosa offers improved bioavailability and quick onset of action of the drug, main disadvantage associated with nasal drug delivery is mucocilliary clearance due to which drug particles get cleared from the nose before complete absorption through nasal mucosa. Therefore, mucoadhesive polymeric approach can be successfully used to enhance the retention of the drug on nasal mucosal surface. Here, some of the aspects of the stimuli responsive polymers have been discussed which possess liquid state at the room temperature and in response to nasal temperature, pH and ions present in mucous, can undergo in situ gelation in nasal cavity. In this review, several temperature responsive, pH responsive and ion responsive polymers used in nasal delivery, their gelling mechanisms have been discussed. Smart polymers not only able to enhance the retention of the drug in nasal cavity but also provide controlled release, ease of administration, enhanced permeation of the drug and protection of the drug from mucosal enzymes. Thus smart polymeric approach can be effectively used for nasal delivery of peptide drugs, central nervous system dugs and hormones.

  17. On the behaviour of gelled fibre suspensions in steady shear

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, Bettina [Unilever Corporate Research, Bedford (United Kingdom); University of Nottingham, Division of Food Sciences, Loughborough (United Kingdom); White, Duncan; Melrose, John R.; Frith, William J. [Unilever Corporate Research, Bedford (United Kingdom)

    2007-03-15

    The shear rheological properties of suspensions of gelled agar fibres in a low viscosity Newtonian matrix fluid were investigated. Two classes of fibres, low aspect ratio fibres and high aspect ratio fibres with an aspect ratio of the order of 10 and 100 respectively were included in the investigations. For all fibre phase volumes investigated, from as low as 0.01 upwards, the flow curves are characterised by an apparent yield stress followed by shear-thinning which was independent of the fibre aspect ratio. Based on our analysis of the flow curves, we conclude that the high aspect ratio fibres behave like flexible threads in contrast to the low aspect ratio fibres whose high shear relative viscosity is successfully described by a relation for long rigid rods. These findings are supported by flow visualisation using an optical shearing stage coupled to a light microscope. (orig.)

  18. All-polymer microfluidic systems for droplet based sample analysis

    DEFF Research Database (Denmark)

    Poulsen, Carl Esben

    In this PhD project, I pursued to develop an all-polymer injection moulded microfluidic platform with integrated droplet based single cell interrogation. To allow for a proper ”one device - one experiment” methodology and to ensure a high relevancy to non-academic settings, the systems presented...... bonded by ultrasonic welding. In the sub-projects of this PhD, improvements have been made to multiple aspects of fabricating and conducting droplet (or multiphase) microfluidics: • Design phase: Numerical prediction of the capillary burst pressure of a multiphase system. • Fabrication: Two new types...... here were fabricated exclusive using commercially relevant fabrication methods such as injection moulding and ultrasonic welding. Further, to reduce the complexity of the final system, I have worked towards an all-in-one device which includes sample loading, priming (removal of air), droplet formation...

  19. Smart branched polymer drug conjugates as nano-sized drug delivery systems.

    Science.gov (United States)

    Duro-Castano, A; Movellan, J; Vicent, M J

    2015-10-15

    Polymer-drug conjugates represent excellent nanopharmaceutical candidates, as they offer multiple advantages related to their intrinsic characteristics. Many of the said characteristics are provided by the covalent bonding between the drug and the polymer. However, their clinical development has been slow and only one polymer-drug conjugate has reached the market, thus there remains an urgent need for the development of new and smart polymeric systems. Desirable characteristics of these new systems include higher molecular weight and degree of homogeneity, predictable conformations in solution, multivalency, and increased drug loading capacity, amongst others. With these aims in mind, branched polymers are ideal candidates due to their unique rheological, mechanical, and biomedical properties derived from their structure, inaccessible for linear polymers. Within this review, the synthetic strategies developed and the main efforts towards branched polymer implementation as carriers for polymer-drug conjugates will be addressed.

  20. Hydrogen-fueled polymer electrolyte fuel cell systems for transportation.

    Energy Technology Data Exchange (ETDEWEB)

    Ahluwalia, R.; Doss, E.D.; Kumar, R.

    1998-10-19

    The performance of a polymer electrolyte fuel cell (PEFC) system that is fueled directly by hydrogen has been evaluated for transportation vehicles. The performance was simulated using a systems analysis code and a vehicle analysis code. The results indicate that, at the design point for a 50-kW PEFC system, the system efficiency is above 50%. The efficiency improves at partial load and approaches 60% at 40% load, as the fuel cell operating point moves to lower current densities on the voltage-current characteristic curve. At much lower loads, the system efficiency drops because of the deterioration in the performance of the compressor, expander, and, eventually, the fuel cell. The results also indicate that the PEFC system can start rapidly from ambient temperatures. Depending on the specific weight of the fuel cell (1.6 kg/kW in this case), the system takes up to 180s to reach its design operating conditions. The PEFC system has been evaluated for three mid-size vehicles: the 1995 Chrysler Sedan, the near-term Ford AIV (Aluminum Intensive Vehicle) Sable, and the future P2000 vehicle. The results show that the PEFC system can meet the demands of the Federal Urban Driving Schedule and the Highway driving cycles, for both warm and cold start-up conditions. The results also indicate that the P2000 vehicle can meet the fuel economy goal of 80 miles per gallon of gasoline (equivalent).

  1. Tuning of electrostatic vs. depletion interaction in deciding the phase behavior of nanoparticle-polymer system

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Sugam, E-mail: sugam@barc.gov.in; Aswal, V. K. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Kohlbrecher, J. [Laboratory for Neutron Scattering, Paul Scherrer Institut, H-5232 PSI Villigen (Switzerland)

    2015-06-24

    Nanoparticle-polymer system interestingly show a re-entrant phase behavior where charge stabilized silica nanoparticles (phase I) undergo particle clustering (phase II) and then back to individual particles (phase I) as a function of polymer concentration. Such phase behavior arises as a result of dominance of various interactions (i) nanoparticle-nanoparticle electrostatic repulsion (ii) polymer induced attractive depletion between nanoparticles and (iii) polymer-polymer repulsion, at different concentration regimes. Small-angle neutron scattering (SANS) has been used to study the evolution of interaction during this re-entrant phase behavior of nanoparticles by contrast-marching the polymer. The SANS data have been modeled using a two-Yukawa potential accounting for both attractive and repulsive parts of the interaction between nanoparticles. The degree of both of these parts has been separately tuned by varying the polymer concentration and ionic strength of the solution. Both of these parts are found to have long-range nature. At low polymer concentrations, the electrostatic repulsion dominates over the depletion attraction. The magnitude and the range of the depletion interaction increase with the polymer concentration leading to nanoparticle clustering. At higher polymer concentrations, the increased polymer-polymer repulsion reduces the strength of depletion leading to re-entrant phase behavior. The clusters formed under depletion attraction are found to have surface fractal morphology.

  2. 75 FR 53277 - Notice of Workshop on Polymers for Photovoltaic Systems

    Science.gov (United States)

    2010-08-31

    ... National Institute of Standards and Technology Notice of Workshop on Polymers for Photovoltaic Systems... Photovoltaic Systems. DATES: The workshop will be held over two days, Thursday, September 23, 8:30 a.m. to 5 p... polymeric materials used in photovoltaic systems; testing, performance, and reliability of polymers...

  3. Conducting polymer actuators: From basic concepts to proprioceptive systems

    Science.gov (United States)

    Martinez Gil, Jose Gabriel

    Designers and engineers have been dreaming for decades of motors sensing, by themselves, working and surrounding conditions, as biological muscles do originating proprioception. Here bilayer full polymeric artificial muscles were checked up to very high cathodic potential limits (-2.5 V) in aqueous solution by cyclic voltammetry. The electrochemical driven exchange of ions from the conducting polymer film, and the concomitant Faradaic bending movement of the muscle, takes place in the full studied potential range. The presence of trapped counterion after deep reduction was corroborated by EDX determinations giving quite high electronic conductivity to the device. The large bending movement was used as a tool to quantify the amount of water exchanged per reaction unit (exchanged electron or ion). The potential evolutions of self-supported films of conducting polymers or conducting polymers (polypyrrole, polyaniline) coating different microfibers, during its oxidation/reduction senses working mechanical, thermal, chemical or electrical variables. The evolution of the muscle potential from electrochemical artificial muscles based on electroactive materials such as intrinsically conducting polymers and driven by constant currents senses, while working, any variation of the mechanical (trailed mass, obstacles, pressure, strain or stress), thermal or chemical conditions of work. One physically uniform artificial muscle includes one electrochemical motor and several sensors working simultaneously under the same driving reaction. Actuating (current and charge) and sensing (potential and energy) magnitudes are present, simultaneously, in the only two connecting wires and can be read by the computer at any time. From basic polymeric, mechanical and electrochemical principles a physicochemical equation describing artificial proprioception has been developed. It includes and describes, simultaneously, the evolution of the muscle potential during actuation as a function of the

  4. INVESTIGATION OF STRUCTURE AND PROPERTIES FOR POLYMER SYSTEMS BASED ON DYNAMIC RHEOLOGICAL APPROACHES

    Institute of Scientific and Technical Information of China (English)

    Qiang Zheng; Min Zuo

    2005-01-01

    The dynamic rheological measurements have been a preferred approach to the characterization of the structure and properties for multi-component or multi-phase polymer systems, due to its sensitive response to changes of structure for these heterogeneous polymers. In the present article, recent progresses in the studies on dynamic theology for heterogeneous polymer systems including polymeric composites filled with inorganic particles, thermo-oxidized polyolefins, phaseseparated polymeric blends and functional polymers with the scaling and percolation behavior are reviewed, mainly depending on the results by the authors' group. By means of rheological measurements, not only some new fingerprints responsible for the evolution of morphology and structure concerning these polymer systems are obtained, the corresponding results are also significant for the design and preparation of novel polymer-based composites and functional materials.

  5. Use of psyllium (isubgol) husk as an alternative gelling agent for the ...

    African Journals Online (AJOL)

    SERVER

    2008-04-17

    Apr 17, 2008 ... microalgae (Cyanobacteria) Chroococcus limneticus and eukaryotic green ... psyllium husk were far lower than 722000 cells mL-1 on agar gelled ..... Evidence for the recognition of a secondary structure of carrageenan.

  6. Studies of efficiency in a perforated rotating disc contactor using a polymer-polymer aqueous two-phase systems

    Directory of Open Access Journals (Sweden)

    L. A. Sarubbo

    2005-09-01

    Full Text Available The mass transfer process in a perforated rotating disc contactor (PRDC using a polymer-polymer aqueous two-phase system was investigated. The results show that the efficiency did not show a regular trend with the increase of the dispersed phase velocity and increased with the rotation velocity. The separation efficiency was higher for three rotating discs than for four discs. The increase in tie-line length decreased the efficiency. The separation efficiency reached high values, about 96% under conditions studied in this work.

  7. Evaluation of gelling agents on anther culture : response of two soybean cultivars

    OpenAIRE

    Milena Barcelos Cardoso; Maria Helena Bodanese-Zanettini; Elsa Cristina de Mundstock; Eliane Kaltchuk-Santos

    2007-01-01

    Anthers of two soybean cultivars were cultured in B5 long basal culture media gelled with agarose or PhytagelTM. Cytological examinations of the anthers were carried out during the first 45 days of culture to assay the viability and developmental stage of microspores. Frequency of callus formation was recorded at 45 days of culture. The analysis of variance of the microspore viability assay showed significant Cultivar X Gelling Agent X Day of Culture interactions. The frequencies of viable mi...

  8. METAL-POLYMER SOLAR COLLECTORS WITH MULTICHANNEL ABSORBER FOR MULTIFUNCTIONAL MULTIPURPOSE ENERGY SYSTEMS

    Directory of Open Access Journals (Sweden)

    Doroshenko A.

    2012-08-01

    Full Text Available New modification of liquid-metal-polymer solar collector for solar heating and for creation of multifunctional energy systems on its basis, particularly solar refrigeration systems was developed. A comparative study of several modifications of polymer collectors involving data of a set of foreign researchers was made and high efficiency of the new elaboration was proven.

  9. Electronic excited states and relaxation dynamics in polymer heterojunction systems

    Science.gov (United States)

    Ramon, John Glenn Santos

    The potential for using conducting polymers as the active material in optoelectronic devices has come to fruition in the past few years. Understanding the fundamental photophysics behind their operations points to the significant role played by the polymer interface in their performance. Current device architectures involve the use of bulk heterojunctions which intimately blend the donor and acceptor polymers to significantly increase not only their interfacial surface area but also the probability of exciton formation within the vicinity of the interface. In this dissertation, we detail the role played by the interface on the behavior and performance of bulk heterojunction systems. First, we explore the relation between the exciton binding energy to the band offset in determining device characteristics. As a general rule, when the exciton binding energy is greater than the band offset, the exciton remains the lowest energy excited state leading to efficient light-emitting properties. On the other hand, if the offset is greater than the binding energy, charge separation becomes favorable leading to better photovoltaic behavior. Here, we use a Wannier function, configuration interaction based approach to examine the essential excited states and predict the vibronic absorption and emission spectra of the PPV/BBL, TFB/F8BT and PFB/F8BT heterojunctions. Our results underscore the role of vibrational relaxation in the formation of charge-transfer states following photoexcitation. In addition, we look at the relaxation dynamics that occur upon photoexcitation. For this, we adopt the Marcus-Hush semiclassical method to account for lattice reorganization in the calculation of the interconversion rates in TFB/F8BT and PFB/F8BT. We find that, while a tightly bound charge-transfer state (exciplex) remains the lowest excited state, a regeneration pathway to the optically active lowest excitonic state in TFB/F8BT is possible via thermal repopulation from the exciplex. Finally

  10. Optimal system size for emergence of self-replicating polymer system

    CERN Document Server

    Matsubara, Yoshiya J

    2015-01-01

    A biological system consists of a variety of polymers that are synthesized from monomers, by catalysis that exists only for some long polymers. It is important to elucidate the emergence and sustenance of such autocatalytic polymerization. We analyze here the stochastic polymerization reaction dynamics, to investigate the transition time from a state with almost no catalysts to a state with sufficient catalysts. We found an optimal volume that minimizes this transition time, which agrees with the inverse of the catalyst concentration at the unstable fixed point that separates the two states, as is theoretically explained. Relevance to the origin of life is also discussed.

  11. Norbornylene-based polymer systems for dielectric applications

    Science.gov (United States)

    Dirk, Shawn M [Albuquerque, NM; Wheeler, David R [Albuquerque, NM

    2012-07-17

    A capacitor having at least one electrode pair being separated by a dielectric component, with the dielectric component being made of a polymer such as a norbornylene-containing polymer with a dielectric constant greater than 3 and a dissipation factor less than 0.1 where the capacitor has an operating temperature greater than 100.degree. C. and less than 170.degree. C.

  12. Temperature-responsive compounds as in situ gelling biomedical materials.

    Science.gov (United States)

    Moon, Hyo Jung; Ko, Du Young; Park, Min Hee; Joo, Min Kyung; Jeong, Byeongmoon

    2012-07-21

    Aqueous solutions that undergo sol-to-gel transition as the temperature increases have been extensively studied during the last decade. The material can be designed by controlling the hydrophilic and hydrophobic balance of the material. Basically, the molecular weight of the hydrophilic block and hydrophobic block of a compound should be fine-tuned from the synthetic point of view. In addition, stereochemistry, microsequence, topology, and nanostructures of the compound also affect the transition temperature, gel window, phase diagram, and modulus of the gel. From a practical point of view, biodegradability, biocompatibility, and interactions between the material and drug or cell should be considered in designing a thermogelling material. The interactions are particularly important in that they control drug release profile and initial burst release of the drug in the drug delivery system, and affect cell proliferation, differentiation, and biomarker expression in three-dimensional cell culture and tissue engineering application. This review provides an in-depth summary of the recent progress of thermogelling systems including polymers, low molecular compounds, and nanoemulsions. Their biomedical applications were also comparatively discussed. In addition, perspectives on future material design of a new thermogelling material and its application are suggested.

  13. Novel pH-sensitive biodegradable polymeric drug delivery systems based on ketal polymers.

    Science.gov (United States)

    Chen, Daquan; Wang, Hongbo

    2014-01-01

    This article reviews the recent developments on novel pH-sensitive ketal-based biodegradable polymeric drug delivery systems. Due to the degradation of ketal derivatives, neutral alcohols and ketones, ketal derivatives can be used to fabricate pH-degradable polymer with pH-degradable ketal linkages in new drug delivery systems by avoiding inflammatory problems. Due to the novelty of ketal polymers, there were few reports about ketal polymers. The review starts with a brief introduction to the pH-sensitive drug delivery system, followed by the structure, preparation and characterization techniques of ketal polymers. Thereafter, the promising applications in various diseases in relation to micro/nano drug carriers based on ketal polymers are summarized and discussed.

  14. Chemically Methylated and Reduced Pectins: Preparation and Characterisation by 1H-NMR Spectroscopy, Enzymatic Degradation and Gelling Properties

    DEFF Research Database (Denmark)

    Rosenbohm, Christoph; Lundt, Inge; Christensen, T.M.I.E.;

    2003-01-01

    The gelling properties of pectin are known to be closely related to the degree of methylation (DM) and the distribution of the ester groups. In order to investigate this dependency, a natural citrus pectin (DM=64%) has been methylated to pectins with higher DM’s or saponified to achieve pectins...... than with unmodified pectin. The new reduced pectins exhibit high gelling properties. Keywords: Pectin; Methylation; Deesterification; Reduction; DM and DR by 1H-NMR spectroscopy; Reduced Pectin; Pectinases; Gelling properties....

  15. Optimization of a gelled emulsion intended to supply ω-3 fatty acids into meat products by means of response surface methodology.

    Science.gov (United States)

    Poyato, Candelaria; Ansorena, Diana; Berasategi, Izaskun; Navarro-Blasco, Iñigo; Astiasarán, Iciar

    2014-12-01

    The optimization of a gelled oil-in-water emulsion was performed for use as fat replacer in the formulation of ω-3 PUFA-enriched cooked meat products. The linseed oil content, carrageenan concentration and surfactant-oil ratio were properly combined in a surface response design for maximizing the hardness and minimizing the syneresis of the PUFA delivery system. The optimal formulation resulted in a gelled emulsion containing 40% of oil and 1.5% of carrageenan, keeping a surfactant-oil ratio of 0.003. The gel was applied as a partial fat replacer in a Bologna-type sausage and compared to the use of an O/W emulsion also enriched in ω-3. Both experimental sausages contributed with higher ω-3 PUFA content than the control. No sensory differences were found among formulations. The selected optimized gelled oil-in-water emulsion was demonstrated to be a suitable lipophilic delivery system for ω-3 PUFA compounds and applicable in food formulations as fat replacer.

  16. Effects of carbon nanoparticles on properties of thermoset polymer systems

    Science.gov (United States)

    Movva, Siva Subramanyam

    Polymer nanocomposites are novel materials in which at least one of the dimensions of the reinforcing material is on the order of 100 nm or less. While thermoplastic nanocomposites have been studied very widely, there are fewer studies concerning the effect of nanoparticles on thermoset systems. Low temperature cure thermoset systems are very important for many important applications. In this study, the processing, mechanical and thermal properties and reaction kinetics of carbon nanofiber (CNF) and/or carbon nanotubes (CNT) reinforced low temperature vinyl ester and epoxy nanocomposites were studied. In the first part, the processing challenge of incorporating CNFs into conventional fiber reinforced composites made by Vacuum infusion resin transfer molding (VARTM) was addressed by a new technique. The CNFs are pre-bound on the long fiber mats, instead of mixing them in the polymer resin, thereby eliminating several processing drawbacks. The resulting hybrid nanocomposites showed significant improvements in tensile, flexural and thermal properties. The effect of CNFs on the mold filling in VARTM was also studied and shown to follow the Darcy's law. In the second part, the effect of CNFs on the low temperature cure kinetics of vinyl ester and epoxy resins is studied using a thermal analysis technique, namely Differential scanning calorimetry (DSC). The effect of CNFs on the free radical polymerization of vinyl esters was found to be very complex as the CNFs interact with the various curing ingredients in the formulation. Specifically, the interaction effects of CNFs and the inhibitor were studied and a reaction mechanism was proposed to explain the observed phenomenon. The effect of surface modification of the carbon nanoparticles on the cure kinetics of wind-blade epoxy was studied. The surface functionalization reduced the activation energy of the epoxy reaction and was found to have an acceleration effect on the cure kinetics of epoxy resin at room temperature

  17. Experimental beam system studies of plasma-polymer interactions

    Science.gov (United States)

    Nest, Dustin George

    Since the invention of the integrated circuit, the semiconductor industry has relied on the shrinking of device dimensions to increase device performance and decrease manufacturing costs. However, the high degree of roughening observed during plasma etching of current generation photoresist (PR) polymers can result in poor pattern transfer and ultimately decreased device performance or failure. Plasma-surface interactions are inherently difficult to study due to the highly coupled nature of the plasma enviroment. To better understand these interactions, a beam system approach is employed where polymers are exposed to beams of ions and vacuum ultraviolet (VUV) photons. Through the use of the beam system approach, simultaneous VUV radiation, ion bombardment, and moderate substrate heating have been identified as key elements, acting synergistically, as being responsible for roughening of current generation 193 nm PR during plasma processing. Sequential exposure is not adequate for the development of surface roughness, as observed through AFM and SEM. Ion bombardment results in the formation of a graphitized near-surface region with a depth of a few nanometers, the expected ion penetration depth of 150 eV argon ions. In contrast, VUV radiation results in the loss of carbon-oxygen bonds in the bulk PR as observed through Transmission FTIR. Based on the differing penetration depth of either ions or photons, their resulting chemical modifications, and the temperature dependence of the observed roughening, a mechanism is proposed based on stress relaxation resulting in surface buckling. The surface roughness of poly(4-methyl styrene) (P4MS) and poly(alpha-methyl styrene) (PalphaMS) have also been investigated under exposure to ions and VUV photons. PaMS degrades during VUV radiation above its ceiling temperature of ˜60°C. Despite having the same chemical composition as PalphaMS, P4MS does not degrade during VUV exposure at 70°C due to its relatively high ceiling

  18. Exploration of the nature of a unique natural polymer-based thermosensitive hydrogel.

    Science.gov (United States)

    Lu, Shanling; Yang, Yuhong; Yao, Jinrong; Shao, Zhengzhong; Chen, Xin

    2016-01-14

    The chitosan (CS)/β-glycerol phosphate (GP) system is a heat induced gelling system with a promising potential application, such as an injectable biomedical material. Unlike most thermosensitive gelling systems, the CS/GP system is only partially reversible. That is once the hydrogel is fully matured, it only softens but cannot go back to its initial liquid state when cooled down. Here, we perform both the small and large amplitude oscillatory shear (SAOS and LAOS) tests on the fully matured CS/GP hydrogel samples at a variety of temperatures within the cooling process. The purpose of such tests is to investigate the structural change of the hydrogel network and thus to understand the possible gelation mechanism of this unique thermosensitive hydrogel. From the LAOS results and the further analysis with the Chebyshev expansion method, it shows that the CS/GP hydrogel is composed of a colloidal network dominated by hydrophobic interactions at high temperature, and gradually turns into a flexible network dominated by hydrogen bonding when the temperature goes down. Therefore, we may conclude that LOAS is a powerful tool to study the nonlinear behaviour of a polymer system that is closely related to its structure, and as a practical example, we achieve a clearer vision on the gelation mechanism of the unique CS/GP thermosensitive hydrogel on the basis of considerable previous studies and assumptions in this laboratory and other research groups.

  19. Correlation between rheological behavior and structure of multi-component polymer systems

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Rheological measurement has been an effective method to characterize the structure and properties for multiphase/multi-component polymers, owing to its sensitivity to the structure change of hetero geneous systems. In this article, recent progress in the studies on the morphology/structure and rheological properties of heterogeneous systems is summarized, mainly reporting the findings of the authors and their collaborators, involving the correlation between the morphology and viscoelastic relaxation of LCST-type polymer blends, the microstructure and linear/nonlinear viscoelastic behavior of block copolymers, time scaling of shear-induced crystallization and rheological response of polyolefins, and the relationship between the structure/properties and rheological behavior of filled polymer blends. It is suggested that a thorough understanding of the characteristic rheological response to the morphology/structure evolution of multiphase/multi-component polymers facilitates researchers' optimizing the morphology/structure and ultimate mechanical properties of polymer materials.

  20. Correlation between rheological behavior and structure of multi-component polymer systems

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Rheological measurement has been an effective method to characterize the structure and properties for multiphase/multi-component polymers, owing to its sensitivity to the structure change of hetero- geneous systems. In this article, recent progress in the studies on the morphology/structure and rheological properties of heterogeneous systems is summarized, mainly reporting the findings of the authors and their collaborators, involving the correlation between the morphology and viscoelastic relaxation of LCST-type polymer blends, the microstructure and linear/nonlinear viscoelastic behavior of block copolymers, time scaling of shear-induced crystallization and rheological response of poly- olefins, and the relationship between the structure/properties and rheological behavior of filled polymer blends. It is suggested that a thorough understanding of the characteristic rheological response to the morphology/structure evolution of multiphase/multi-component polymers facilitates researchers’ op- timizing the morphology/structure and ultimate mechanical properties of polymer materials.

  1. Intramolecular Flexibility of Relatively Rigid Polymers, and Intermolecular Interactions in Ordered Polymer Systems. Part II.

    Science.gov (United States)

    1981-01-26

    rials, the ordering of the chains, and the mechanical strenth of the resulting films or fibers . The basic goals are thus a molecular understanding of...polymers, cis and trans polybenzoxazoles (PBO) and polybenzothiazoles (PBT), form such phases, and energy calculations were therefore carried out to...Phys., 18, 000 (1981). 2. Phenylene Group Rotations and Nonplanar Conformations in Some Cis and Trans Polybenzoxazoles and Polybenzothiazoles, W. J

  2. Evaluation of bioadhesive polymers as delivery systems for nose to brain delivery: in vitro characterisation studies.

    Science.gov (United States)

    Charlton, S T; Davis, S S; Illum, L

    2007-04-01

    There is an increasing need for nasal drug delivery systems that could improve the efficiency of the direct nose to brain pathway especially for drugs for treatment of central nervous system disorders. Novel approaches that are able to combine active targeting of a formulation to the olfactory region with controlled release bioadhesive characteristics, for maintaining the drug on the absorption site are suggested. If necessary an absorption enhancer could be incorporated. Low methylated pectins have been shown to gel and be retained in the nasal cavity after deposition. Chitosan is known to be bioadhesive and also to work as an absorption enhancer. Consequently, two types of pectins, LM-5 and LM-12, together with chitosan G210, were selected for characterisation in terms of molecular weight, gelling ability and viscosity. Furthermore, studies on the in vitro release of model drugs from candidate formulations and the transport of drugs across MDCK1 cell monolayers in the presence of pectin and chitosan were also performed. Bioadhesive formulations providing controlled release with increased or decreased epithelial transport were developed. Due to their promising characteristics 3% LM-5, 1% LM-12 pectin and 1% chitosan G210 formulations were selected for further biological evaluation in animal models.

  3. Injectable pectin hydrogels produced by internal gelation: pH dependence of gelling and rheological properties.

    Science.gov (United States)

    Moreira, Helena R; Munarin, Fabiola; Gentilini, Roberta; Visai, Livia; Granja, Pedro L; Tanzi, Maria Cristina; Petrini, Paola

    2014-03-15

    The production of injectable pectin hydrogels by internal gelation with calcium carbonate is proposed. The pH of pectin was increased with NaOH or NaHCO3 to reach physiological values. The determination of the equivalence point provided evidence that the pH can be more precisely modulated with NaHCO3 than with NaOH. Degradation and inability to gel was observed for pectin solutions with pH 5.35 or higher. Therefore, pectin solutions with pH values varying from 3.2 (native pH) to 3.8 were chosen to produce the gels. The increase of the pH for the crosslinked hydrogels, as well as the reduction of the gelling time and their thickening, was dependent upon the amount of calcium carbonate, as confirmed by rheology. Hydrogel extracts were not cytotoxic for L-929 fibroblasts. On the overall, the investigated formulations represent interesting injectable systems providing an adequate microenvironment for cell, drug or bioactive molecules delivery.

  4. From short to long distances with Gell-Mann--Low Renormalization group

    Science.gov (United States)

    Dunjko, Vanja; Olshanii, Maxim

    2004-05-01

    Computing correlation functions is an important and formidable problem of many-body physics. For 1D gapless systems, Haldane's theory gives exponents of large distance expansions, model details entering through speed of sound. The prefactors depend on high-energy cutoffs, and it is unclear which model-dependent parameters set them. ..We present a method very well-suited for the approximate computation of the leading order prefactor, with short-distance expansion as an input. Our basis is the Gell-Mann--Low Renormalization Group, and optimism about sufficient analyticity of correlation functions. In the test case of Tonks-Girardeau gas, a rare model where both short and long-distance expansions are known, already the first non-zero subleading term of the short-distance expansion gives the long-distance prefactor to within 15%. ..While Wilson's Renormalization Group makes high energy cutoffs irrelevant, we actually determine them for Haldane model. A byproduct of our method is an interpolation between short and long-distance behaviors, which we use to treat interaction-induced decoherence in atom interferometers.

  5. Evaluation of guar gum derivatives as gelling agents for microbial culture media.

    Science.gov (United States)

    Gangotri, Waikhom; Jain-Raina, Ruchi; Babbar, Shashi B

    2012-05-01

    Guar gum, a galactomannan, has been reported to be an inexpensive substitute of agar for microbial culture media. However, its use is restricted probably because of (1) its highly viscous nature even at high temperatures, making dispensing of the media to Petri plates difficult and (2) lesser clarity of the guar gum gelled media than agar media due to impurities present in guar gum. To overcome these problems, three guar gum derivatives, carboxymethyl guar, carboxymethyl hydroxypropyl guar and hydroxypropyl guar, were tested as gelling agents for microbial growth and differentiation. These were also evaluated for their suitability for other routine microbiological methods, such as, enumeration, use of selective and differential media, and antibiotic sensitivity test. For evaluation purpose, growth and differentiation of eight fungi and eight bacteria grown on the media gelled with agar (1.5%), guar gum (4%) or one of the guar gum derivatives (4%), were compared. All fungi and bacteria exhibited normal growth and differentiation on all these media. Generally, growth of most of the fungi was better on guar gum derivatives gelled medium than on agar medium. The enumeration carried out for Serratia sp. and Pseudomonas aeruginosa by serial dilution and pour plate method yielded similar counts in all the treatments. Likewise, the selective succinate medium, specific for P. aeruginosa, did not allow growth of co-inoculated Bacillus sp. even if gelled with guar gum derivatives. The differential medium, Congo red mannitol agar could not differentiate between Agrobacterium tumefaciens and Rhizobium meliloti on color basis, if gelled with guar gum or any of its derivatives However, for antibiotic sensitivity tests for both Gram-positive and -negative bacteria, guar gum and its derivatives were as effective as agar.

  6. Gelling and curing behaviors of benzoxazine/epoxy formulations containing 4,4 Prime -thiodiphenol accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Chow, W.S., E-mail: chowwenshyang@yahoo.com [Institut fuer Verbundwerkstoffe GmbH (Institute for Composite Materials), Kaiserslautern University of Technology, D-67663 Kaiserslautern (Germany); School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, Nibong Tebal 14300, Penang (Malaysia); Grishchuk, S.; Burkhart, T. [Institut fuer Verbundwerkstoffe GmbH (Institute for Composite Materials), Kaiserslautern University of Technology, D-67663 Kaiserslautern (Germany); Karger-Kocsis, J. [Polymer Technology, Faculty of Engineering and the Built Environment, Tshwane University of Technology, Pretoria 0001 (South Africa); Department of Polymer Engineering, Faculty of Mechanical Engineering, Budapest University of Technology and Economics, H-1111 Budapest (Hungary)

    2012-09-10

    Highlights: Black-Right-Pointing-Pointer Gelling and curing behaviors of benzoxazine/epoxy with accelerator were studied. Black-Right-Pointing-Pointer The activation energy of gelling was assessed by Arrhenius equation. Black-Right-Pointing-Pointer The activation energy of curing was determined from dynamic DSC scans. Black-Right-Pointing-Pointer 4,4 Prime -Thiodiphenol can act as co-reactive accelerator for benzoxazine/epoxy blends. Black-Right-Pointing-Pointer 4,4 Prime -Thiodiphenol markedly reduced the gel time and the activation energy. - Abstract: Benzoxazine (BOX)/diglycidyl ether of bisphenol A (DGEBA) based epoxy resins (BOX/DGEBA = 100/0, 75/25 and 50/50 wt.%) with and without 4,4 Prime -thiodiphenol accelerator (DT300) were prepared. The gelling and curing behaviors of the BOX and BOX/DGEBA mixtures in presence and absence of DT300 (10 parts per hundred resin, phr) were investigated using plate-plate rheometry and differential scanning calorimetry (DSC). The gel time was determined in isothermal scans at three different temperatures (T = 180, 200, and 220 Degree-Sign C). Dynamic DSC scans were registered at four heating rates ({beta} = 5, 10, 15, and 20 Degree-Sign C min{sup -1}, respectively). The activation energy of gelling was assessed by an Arrhenius, whereas that of the curing by the Kissinger and Ozawa methods. Combination of BOX with DGEBA delayed the gel formation and increased the activation energy of both gelling and curing processes compared to neat BOX resin. By contrast, addition of 4,4 Prime -thiodiphenol as co-reactive accelerator markedly reduced the gel time and the activation energy of both gelling and curing of BOX and BOX/DGEBA formulations.

  7. Development of a polymer based fiberoptic magnetostrictive metal detector system.

    Science.gov (United States)

    Hua, Wei Shu; Hooks, Joshua Rosenberg; Wu, Wen Jong; Wang, Wei Chih

    2010-10-01

    This paper presents a new metal detector using a fiberoptic magnetostriction sensor. The metal sensor uses a fiber-optic Mach-Zehnder interferometer with a newly developed ferromagnetic polymer as the magnetostrictive sensing material. This polymeric magnetostrictive fiberoptic metal sensor is simple to fabricate, small in size, and resistant to RF interference (which is common in typical electromagnetic type metal detectors). Metal detection is based on disruption of the magnetic flux density across the magnetostriction sensor. In this paper, characteristics of the material being sensed and magnetic properties of the ferromagnetic polymers will be discussed.

  8. Integrated lasers for polymer Lab-on-a-Chip systems

    DEFF Research Database (Denmark)

    Mappes, Timo; Vannahme, Christoph; Grosmann, Tobias

    2012-01-01

    We develop optical Lab-on-a-Chips on different platforms for marker-based and label-free biophotonic sensor applications. Our chips are based on polymers and fabricated by mass production technologies to integrate microfluidic channels, optical waveguides and miniaturized lasers.......We develop optical Lab-on-a-Chips on different platforms for marker-based and label-free biophotonic sensor applications. Our chips are based on polymers and fabricated by mass production technologies to integrate microfluidic channels, optical waveguides and miniaturized lasers....

  9. Polymer multilevel lab-on-chip systems for electrochemical sensing

    DEFF Research Database (Denmark)

    Matteucci, Marco; Larsen, Simon Tylsgaard; Garau, Alessandro

    2013-01-01

    with depths as small as tens of nanometers and as big as hundreds of microns on the same polymer chip. The authors also describe in detail the fabrication procedure of polymer substrates with embedded Au and pedot:tosylate electrodes for electrochemical applications. The electrode fabrication process...... is simple and fit for integration in a production scheme. The electrode–substrates are then bonded to injection molded counterparts to be used for electrochemical applications. A dimensional and functional characterization of the electrodes is also presented here....

  10. Papaya pulp gelling: is it premature ripening or problems of water accumulation in the apoplast?

    Directory of Open Access Journals (Sweden)

    Jurandi Gonçalves de Oliveira

    Full Text Available Gelled aspect in papaya fruit is typically confused with premature ripening. This research reports the characterization of this physiological disorder in the pulp of papaya fruit by measuring electrolyte leakage, Pi content, lipid peroxidation, pulp firmness, mineral contents (Ca, Mg and K - in pulp and seed tissues, and histological analysis of pulp tissue. The results showed that the gelled aspect of the papaya fruit pulp is not associated with tissue premature ripening. Data indicate a reduction of the vacuole water intake as the principal cause of the loss of cellular turgor; while the waterlogged aspect of the tissue may be due to water accumulation in the apoplast.

  11. Exploring a direct injection method for microfluidic generation of polymer microgels.

    Science.gov (United States)

    Wang, Yihe; Tumarkin, Ethan; Velasco, Diego; Abolhasani, Milad; Lau, Willie; Kumacheva, Eugenia

    2013-07-07

    Microfluidics (MFs) offers a promising method for the preparation of polymer microgels with exquisite control over their dimensions, shapes and morphologies. A challenging task in this process is the generation of droplets (precursors for microgels) from highly viscous polymer solutions. Spatial separation of MF emulsification and gelation of the precursor droplets on chip can address this challenge. In the present work, we explored the application of the "direct injection" method for the preparation of microgels by adding a highly concentrated polymer solution or a gelling agent directly into the precursor droplets. In the first system, primary droplets were generated from a dilute aqueous solution of agarose, followed by the injection of the concentrated agarose solution directly in the primary droplets. The secondary droplets served as precursors for microgels. In the second system, primary droplets were generated from the low-viscous solution of methyl-β-cyclodextrin and poly(ethylene glycol) end-terminated with octadecyl hydrophobic groups. Addition of surfactant directly into the primary droplets led to the binding of methyl-β-cyclodextrin to the surfactant, thereby releasing hydrophobized poly(ethylene glycol) to form polymer microgels. Our results show that, when optimized, the direct injection method can be used for microgel preparation from highly viscous liquids and thus this method expands the range of polymers used for MF generation of microgels.

  12. Morphological and Thermal Studies of Plasticized Poly (methyl methacrylate) Polymer Electrolyte Systems

    Science.gov (United States)

    Osman, Z.; Chew, K. W.; Othman, L.; Isa, K. B. M.

    2010-03-01

    In the present study, six systems of poly(methylmethacrylate) (PMMA)-based polymer electrolyte films have been prepared using solution casting technique. They are; the pure PMMA system, the plasticized-PMMA systems (PMMA+EC and PMMA+PC), the salted-PMMA system (PMMA+LiBF4) and the plasticized-salted PMMA systems (PMMA+EC+LiBF4 and PMMA+PC+LiBF4). The effect of adding the plasticizers and the salt to the PMMA based polymer electrolyte films on the morphology and thermal properties will be investigated using Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Differential Scanning Calorimetry (DSC). The phase structure and the complexation for each system that has the highest conductivity are characterized using the XRD. The FTIR results confirmed the complexation has taken place between the plasticizers and the polymer, the salt and the polymer, and the plasticizers and the salt. These results are supported by SEM analysis. The glass transition temperature, Tg of polymer electrolyte films will be determined by DSC analysis. The Tg value of the highest conducting film in the (PMMA+EC) system, the (PMMA+PC) system and the (PMMA+LiBF4) system is 117.2° C, 118.8° C and 122.1° C, respectively. The Tg value is decreased with the increased of the amorphous phase.

  13. Precision manufacturing of polymer micro-nano fluidic systems

    DEFF Research Database (Denmark)

    Garnæs, Jørgen; Calaon, Matteo; Tosello, Guido

    2015-01-01

    Lab-on-a-Chip (LoC) technologies require the possibility of fabricating devices which include micro down to sub-micrometre features with high production rate and low cost. In the present study precision injection moulding is performed using a COC Topas 5013 L10 polymer to produce LoC devices...

  14. Ceramic/polymer functionally graded material (FGM) lightweight armor system

    Energy Technology Data Exchange (ETDEWEB)

    Petrovic, J.J.; McClellan, K.J.

    1998-12-31

    This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Functionally graded material is an enabling technology for lightweight body armor improvements. The objective was to demonstrate the ability to produce functionally graded ceramic-polymer and ceramic-metal lightweight armor materials. This objective involved two aspects. The first and key aspect was the development of graded-porosity boron-carbide ceramic microstructures. The second aspect was the development of techniques for liquid infiltration of lightweight metals and polymers into the graded-porosity ceramic. The authors were successful in synthesizing boron-carbide ceramic microstructures with graded porosity. These graded-porosity boron-carbide hot-pressed pieces were then successfully liquid-infiltrated in vacuum with molten aluminum at 1,300 C, and with liquid polymers at room temperature. Thus, they were able to demonstrate the feasibility of producing boron carbide-aluminum and boron carbide-polymer functionally graded materials.

  15. Ceramic/polymer functionally graded material (FGM) lightweight armor system

    Energy Technology Data Exchange (ETDEWEB)

    Petrovic, J.J.; McClellan, K.J.

    1998-12-31

    This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Functionally graded material is an enabling technology for lightweight body armor improvements. The objective was to demonstrate the ability to produce functionally graded ceramic-polymer and ceramic-metal lightweight armor materials. This objective involved two aspects. The first and key aspect was the development of graded-porosity boron-carbide ceramic microstructures. The second aspect was the development of techniques for liquid infiltration of lightweight metals and polymers into the graded-porosity ceramic. The authors were successful in synthesizing boron-carbide ceramic microstructures with graded porosity. These graded-porosity boron-carbide hot-pressed pieces were then successfully liquid-infiltrated in vacuum with molten aluminum at 1,300 C, and with liquid polymers at room temperature. Thus, they were able to demonstrate the feasibility of producing boron carbide-aluminum and boron carbide-polymer functionally graded materials.

  16. Polydiacetylenes: An Ideal Color System for Teaching Polymer Science.

    Science.gov (United States)

    Patel, Gordhan N.; Yang, Nan-Loh

    1983-01-01

    Describes 14 experiments that illustrate, via color changes, a broad scope of fundamental phenomena in polymer science. The experiments, suitable for high school through graduate level, require only test tubes, filter paper, heat source (hot plate or hair drier), and ultra-violet light source. (JN)

  17. Solvent activities of the fluorinated solid polymer electrolyte/water system in fuel cells

    Science.gov (United States)

    Kim, Tae Hwan; Bae, Young Chan

    We modified the lattice fluid equation-of-state by the introducing Debye-Hückel equation. A thermodynamic model taking into account the specific interaction and ionic strength between the polymer and the solvent is proposed. The proposed model successfully predicts the vapor/liquid equilibria (VLE) of solvents and the solid polymer electrolyte (SPE). A generalized lattice fluid model is modified to describe the change of water activity in solid polymer electrolyte (SPE)/water systems. The calculated activity curves using the proposed model agree remarkably well with the experimental data.

  18. Ionotropically gelled novel hydrogel beads: Preparation, characterization and in vitro evaluation

    OpenAIRE

    2011-01-01

    Prolonged release drug delivery system of stavudine was made by ionotropic gelation and polyelectrolyte complexation technique. Cross-linking reinforced chitosan-gellan complex beads were prepared by gelation of anionic gellan gum, the primary polymer, with oppositely charged counter ion to form beads which were further complexed with chitosan as a polyelectrolyte. The effect of this polymer on release profile of drug was studied. Beads without chitosan complexation were also made. The reacti...

  19. PNIPAM Poly (N-isopropylacrylamide: A Thermoresponsive “Smart” Polymer in Novel Drug Delivery Systems

    Directory of Open Access Journals (Sweden)

    Hardik R Mody

    2012-07-01

    Full Text Available Over the past years, extensive research has been carried out in designing and optimizing various drug delivery systems in order to maximize therapeutic effect and minimize unwanted effects of drugs. Many drug carrier systems have been developed on the basis of nanotechnology including systems based on polymeric nanoparticles. Polymeric drug delivery research has been extended to targeting of the drug at the specific site by utilizing various stimuli responsive systems which depend upon physiological conditions of the body such as pH of biological fluids and temperature of the human body. Thermoresponsive polymers with Lower Critical Solution Temperature (LCST have been investigated for various biomedical and pharmaceutical formulations. One such polymer of considerable focus is PNIPAM Poly (N-isopropylacrylamide. PNIPAM is a thermosensitive polymer which has been utilized in many drug delivery systems including for cancer therapeutics. The present article deals with the properties of PNIPAM and their applications in different drug delivery systems.

  20. Development of the computer-aided process planning (CAPP) system for polymer injection molds manufacturing

    OpenAIRE

    J. Tepić; V. Todić; Lukić, D.; Milošević, M.; Borojević, S.

    2011-01-01

    Beginning of production and selling of polymer products largely depends on mold manufacturing. The costs of mold manufacturing have significant share in the final price of a product. The best way to improve and rationalize polymer injection molds production process is by doing mold design automation and manufacturing process planning automation. This paper reviews development of a dedicated process planning system for manufacturing of the mold for injection molding, which integrates computer-...

  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. Molecular engineering of dendritic polymers and their application as drug and gene delivery systems.

    Science.gov (United States)

    Paleos, Constantinos M; Tsiourvas, Dimitris; Sideratou, Zili

    2007-01-01

    This review discusses the development of functional and multifunctional dendrimeric and hyperbranched polymers, collectively called dendritic polymers, with the objective of being applied as drug and gene delivery systems. In particular, using as starting materials known and well-characterized basic dendritic polymers, the review deals with the type of structural modifications to which these dendritic polymers were subjected for the development of drug carriers with low toxicity, high encapsulating capacity, a specificity for certain biological cells, and the ability to be transported through their membranes. Proceeding from functional to multifunctional dendritic polymers, one is able to prepare products that fulfill one or more of these requirements, which an effective drug carrier should exhibit. A common feature of the dendritic polymers is the exhibition of polyvalent interactions, while for multifunctional derivatives, a number of targeting ligands determine specificity, another type of group secures stability in biological milieu and prolonged circulation, while others facilitate their transport through cell membranes. Furthermore, dendritic polymers employed for gene delivery should be or become cationic in the biological environment for the formation of complexes with the negatively charged genetic material.

  3. Synthesis and characterization of an electrolyte system based on a biodegradable polymer

    Directory of Open Access Journals (Sweden)

    K. Sownthari

    2013-06-01

    Full Text Available A polymer electrolyte system has been developed using a biodegradable polymer namely poly-ε-caprolactone (PCL in combination with zinc triflate [Zn(CF3SO32] in different weight percentages and characterized during this investigation. Free-standing thin films of varying compositions were prepared by solution casting technique. The successful doping of the polymer has been confirmed by means of Fourier transform infrared spectroscopy (FTIR by analyzing the carbonyl (C=O stretching region of the polymer. The maximum ionic conductivity obtained at room temperature (25°C was found to be 8.8x10–6 S/cm in the case of PCL complexed with 25 wt% Zn(CF3SO32 which is five orders of magnitude higher than that of the pure polymer host material. The increase in amorphous phase with an increase in salt concentration of the prepared polymer electrolyte has also been confirmed from the concordant results obtained from X-ray diffraction (XRD, differential scanning calorimetry (DSC and scanning electron microscopic (SEM analyses. Furthermore, the electrochemical stability window of the prepared polymer electrolyte was found to be 3.7 V. An electrochemical cell has been fabricated based on Zn/MnO2 electrode couple as an application area and its discharge characteristics were evaluated.

  4. Multicomponent semiconducting polymer systems with low crystallization-induced percolation threshold

    DEFF Research Database (Denmark)

    Goffri, S.; Müller, C.; Stingelin-Stutzmann, N.;

    2006-01-01

    Blends and other multicomponent systems are used in various polymer applications to meet multiple requirements that cannot be fulfilled by a single material1, 2, 3. In polymer optoelectronic devices it is often desirable to combine the semiconducting properties of the conjugated species with the ......Blends and other multicomponent systems are used in various polymer applications to meet multiple requirements that cannot be fulfilled by a single material1, 2, 3. In polymer optoelectronic devices it is often desirable to combine the semiconducting properties of the conjugated species...... of the two components, during which the semiconductor is predominantly expelled to the surfaces of cast films, we can obtain vertically stratified structures in a one-step process. Incorporating these as active layers in polymer field-effect transistors, we find that the concentration of the semiconductor......–crystalline/semiconducting–insulating multicomponent systems offer expanded flexibility for realizing high-performance semiconducting architectures at drastically reduced materials cost with improved mechanical properties and environmental stability, without the need to design all performance requirements into the active semiconducting polymer...

  5. Gelling ability and crystal morphology of sunflower wax in soybean oil

    Science.gov (United States)

    Plant waxes can effectively form organogels with vegetable oils and these organogels have drawn considerable interests as alternatives to solid fats containing trans fats and saturated fats in margarines and spreads. Among them sunflower wax showed the most pronounced gelling ability. In an attempt ...

  6. Cassava starch as an alternative cheap gelling agent for the in vitro ...

    African Journals Online (AJOL)

    SERVER

    2007-07-03

    Jul 3, 2007 ... Potato transplants from the liquid medium and cassava starch gelled medium had .... cant interactions during the three generations of sub- .... biodegradable and poses no threat to the environment on ... provision of potato genotypes and facilities for the ... BSc Dissertation University of Malawi, Bunda.

  7. Effect of various gelling cations on the physical properties of "wet" alginate films.

    Science.gov (United States)

    Harper, B Allison; Barbut, Shai; Lim, Loong-Tak; Marcone, Massimo F

    2014-04-01

    In this study, the physical properties of "wet" alginate films gelled with various divalent cations (Ba(2+) , Ca(2+) , Mg(2+) , Sr(2+) , and Zn(2+) ) were explored. Additionally, the effect of adding NaCl to the alginate film-forming solution prior to gelling was evaluated. Aside from Mg(2+) , all of the divalent cations were able to produce workable "wet" alginate films. Films gelled with BaCl2 (without added NaCl) had the highest (P alginate and Sr-alginate films had the highest elongation at break values. Adding NaCl to the alginate film-forming solution increased the viscosity of the solution. Films with added NaCl were less transparent and had lower tensile strength, elongation, and puncture strength than films formed without NaCl in the film-forming solution. ATR-FTIR results showed a slight shift in the asymmetric COO(-) vibrational peak of the alginate when the "wet" alginate films were gelled with Zn(2+) .

  8. Effect of molecular characteristics of Konjac glucomannan on gelling and rheological properties of Tilapia myofibrillar protein.

    Science.gov (United States)

    Jian, Wenjie; Wu, Huayi; Wu, Lanlan; Wu, Yunhui; Jia, Lina; Pang, Jie; Sun, Yuan-Ming

    2016-10-05

    Konjac glucomannan (KGM) is an important gelling agent in composite gels. This study aimed to investigate the effects of KGM molecular characteristics (molecular weight, size and conformation) on gelling properties of Tilapia myofibrillar protein (TMP). In this work, TMP composite gels were prepared under neutral pH with varying KGM (native KGM, 10kGy-KGM, 20kGy-KGM, and 100kGy-KGM) of different molecular characteristics. Native KGM, 10kGy-KGM, and 20kGy-KGM exerted negative effect on gel strength or whiteness of TMP gels. Interestingly 100kGy-KGM improved gelling properties and whiteness of TMP gels. Such effects presented by varying KGM were attributed the physical filling behaviors and the interaction between KGM and TMP. These behaviors or interactions are resulted from different molecular size and conformation. Smaller molecular size (root-mean square radius, Rz 20.2nm) and approximated spherical conformation in 100kGy-KGM enhanced its interaction with TMP and maintained its compact and smooth structure, but the larger molecular size (Rz≥40.2nm) and random coil conformation in other KGMs inhibited part of actins from gelling and deteriorated the network structure. Our study provided principle knowledge to understand the structure-functions relationships of KGM-TMP composite gels. These results can be used to provide theoretical guidance for surimi gel processing. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Strategy to identify and quantify polysaccharide gums in gelled food concentrates

    NARCIS (Netherlands)

    Grün, C.H.; Sanders, P.; Burg, van der M.; Schuurbiers, E.; Adrichem, van L.; Velzen, van E.J.J.; Roo, de N.; Brunt, K.; Westphal, Y.; Schols, H.A.

    2015-01-01

    A strategy for the unambiguous identification and selective quantification of xanthan gum and locust bean gum (LBG) in gelled food concentrates is presented. DNA detection by polymerase chain reaction (PCR) showed to be a fast, sensitive, and selective method that can be used as a first screening to

  10. Understanding the differences in gelling properties between lupin protein isolate and soy protein isolate

    NARCIS (Netherlands)

    Berghout, J.A.M.; Boom, R.M.; Goot, van der A.J.

    2015-01-01

    The gelling properties of lupin protein isolate (LPI) were compared with those of soy protein isolate (SPI). It was found that LPI behaves fundamentally different than SPI, evidenced by the formation of weaker and deformable gels. Further investigation shows that both protein isolates can be conside

  11. Metallized Gelled Propellants: Oxygen/RP-1/Aluminum Rocket Heat Transfer and Combustion Measurements

    Science.gov (United States)

    Palaszewski, Bryan; Zakany, James S.

    1996-01-01

    A series of rocket engine heat transfer experiments using metallized gelled liquid propellants was conducted. These experiments used a small 20- to 40-lb/f thrust engine composed of a modular injector, igniter, chamber and nozzle. The fuels used were traditional liquid RP-1 and gelled RP-1 with 0-, 5-, and 55-percentage by weight loadings of aluminum particles. Gaseous oxygen was used as the oxidizer. Three different injectors were used during the testing: one for the baseline O(2)/RP-1 tests and two for the gelled and metallized gelled fuel firings. Heat transfer measurements were made with a rocket engine calorimeter chamber and nozzle with a total of 31 cooling channels. Each chamber used a water flow to carry heat away from the chamber and the attached thermocouples and flow meters allowed heat flux estimates at each of the 31 stations. The rocket engine Cstar efficiency for the RP-1 fuel was in the 65-69 percent range, while the gelled 0 percent by weight RP-1 and the 5-percent by weight RP-1 exhibited a Cstar efficiency range of 60 to 62% and 65 to 67%, respectively. The 55-percent by weight RP-1 fuel delivered a 42-47% Cstar efficiency. Comparisons of the heat flux and temperature profiles of the RP-1 and the metallized gelled RP-1/A1 fuels show that the peak nozzle heat fluxes with the metallized gelled O2/RP-1/A1 propellants are substantially higher than the baseline O2/RP-1: up to double the flux for the 55 percent by weight RP-1/A1 over the RP-1 fuel. Analyses showed that the heat transfer to the wall was significantly different for the RP-1/A1 at 55-percent by weight versus the RP-1 fuel. Also, a gellant and an aluminum combustion delay was inferred in the 0 percent and 5-percent by weight RP-1/A1 cases from the decrease in heat flux in the first part of the chamber. A large decrease in heat flux in the last half of the chamber was caused by fuel deposition in the chamber and nozzle. The engine combustion occurred well downstream of the injector face

  12. STUDY ON ION-POLYMER INTERACTION AND MORPHOLOGIC STRUCTURE OF POLYURETHANE/SALT SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    朱卫华; 杨兵; 王新灵; 唐小真

    2001-01-01

    A poly(ethylene oxide) urethane and a model-compound of hard segment(HD) were prepared in this study. Solid polymer electrolytes were got from the blends of polyurethane, HD and NaClO4. The samples were characterized by mean of FT-IR and AFM. Effects of salt concentration on ion-polymer interaction and further on morphologic structure of the composites were investigated and some interesting results were obtained. The results show that HD and concentration of NaClO4 have an important effect on ion-polymer interaction and morphologic structure of the complex. It is also found that in AFM pictures of the samples there is a transition point and ion-polymer interaction of the polyurethane/salt systems play an extremely important role on morphologic structure.

  13. Manufacturing routes for disposable polymer blood diagnostic microfluidic systems

    DEFF Research Database (Denmark)

    Tosello, Guido; Griffiths, Christian; Azcarate, Sabino

    2008-01-01

    -cost and disposable µTBC devices, the micro injection moulding process was selected and therefore a micro tool was required. To overcome the limitations of current existing micro tooling capabilities, a new generation of micro hybrid tooling technologies for micro replication was developed. A metrological approach...... was applied to standardize the different tooling methods employed. The micro tools were then tested with different polymers on different injection moulding machines. The paper provides a comparison of these technologies with a particular focus on the obtainable feature sizes, surface finish, and aspect ratios...

  14. Terminology of Polymers and Polymerization Processes in Dispersed Systems (IUPAC Recommendations 2011

    Directory of Open Access Journals (Sweden)

    Rogošić, M.

    2012-07-01

    Full Text Available A large group of industrially important polymerization processes is carried out in dispersed systems. These processes differ with respect to their physical nature, mechanism of particle formation, particle morphology, size, charge, types of interparticle interactions, and many other aspects. Polymer dispersions, and polymers derived from polymerization in dispersed systems,are used in diverse areas such as paints, adhesives, microelectronics, medicine, cosmetics, biotechnology, and others. Frequently, the same names are used for different processes and products or different names are used for the same processes and products. The document contains a list of recommended terms and definitions necessary for the unambiguous description of processes, products, parameters, and characteristic features relevant to polymers in dispersed systems.

  15. Mechanism and Durability of Repair Systems in Polymer-Modified Cement Mortars

    Directory of Open Access Journals (Sweden)

    Ru Wang

    2015-01-01

    Full Text Available This paper investigated the mechanism and durability of repair systems made of ordinary cement-based repair mortar and three kinds of polymer-modified repair mortars with old concrete, SBR dispersion, SAE dispersion, and SAE powder. By comparing the bonding properties of mortars before and after erosion, it was found that polymers could effectively improve the durability of the repair system and SAE powder had the best improvement. Micromorphology study of the repair mortar and the interface of repair mortar with old concrete through SEM showed that the polymer film formed from SAE powder whatever in the mortar or at the interface was dense and tough, the film formed from SAE dispersion was loose and weak, while the film formed from SBR dispersion was in between them, which explained the difference in the tensile bond strength and the durability of the repair systems.

  16. Surface imprinted thin polymer film systems with selective recognition for bovine serum albumin.

    Science.gov (United States)

    Kryscio, David R; Peppas, Nicholas A

    2012-03-09

    Molecularly imprinted polymers are synthetic antibody mimics formed by the crosslinking of organic or inorganic polymers in the presence of an analyte which yields recognitive polymer networks with specific binding pockets for that biomolecule. Surface imprinted polymers were synthesized via a novel technique for the specific recognition of bovine serum albumin (BSA). Thin films of recognitive networks based on 2-(dimethylamino)ethyl methacrylate (DMAEMA) as the functional monomer and varying amounts of either N,N'-methylenebisacrylamide (MBA) or poly(ethylene glycol) (400) dimethacrylate (PEG400DMA) as the crosslinking agent were synthesized via UV free-radical polymerization and characterized. A clear and reproducible increase in recognition of the template BSA was demonstrated for these systems at 1.6-2.5 times more BSA recognized by the MIP sample relative to the control polymers. Additionally, these polymers exhibited selective recognition of the template relative to competing proteins with up to 2.9 times more BSA adsorbed than either glucose oxidase or bovine hemoglobin. These synthetic antibody mimics hold significant promise as the next generation of robust recognition elements in a wide range of bioassay and biosensor applications.

  17. A review study of (bio)sensor systems based on conducting polymers.

    Science.gov (United States)

    Ates, Murat

    2013-05-01

    This review article concentrates on the electrochemical biosensor systems with conducting polymers. The area of electro-active polymers confined to different electrode surfaces has attracted great attention. Polymer modified carbon substrate electrodes can be designed through polymer screening to provide tremendous improvements in sensitivity, selectivity, stability and reproducibility of the electrode response to detect a variety of analytes. The electro-active films have been used to entrap different enzymes and/or proteins at the electrode surface, but without obvious loss of their bioactivity for the development of biosensors. Electropolymerization is a well-known technique used to immobilize biomaterials to the modified electrode surface. Polymers might be covalently bonding to enzymes or proteins; therefore, thickness, permeation and charge transport characteristics of the polymeric films can be easily and precisely controlled by modulating the electrochemical parameters for various electrochemical techniques, such as chronoamperometry, chronopotentiometry, cyclic voltammetry, and differential pulse voltammetry. This review article is divided into three main parts as given in the table of contents related to the immobilization process of some important conducting polymers, polypyrrole, polythiophene, poly(3,4-ethylenedioxythiophene), polycarbazole, polyaniline, polyphenol, poly(o-phenylenediamine), polyacetylene, polyfuran and their derivatives. A total of 216 references are cited in this review article. The literature reviewed covers a 7 year period beginning from 2005.

  18. Recent progress of the characterization of oppositely charged polymer/surfactant complex in dilution deposition system.

    Science.gov (United States)

    Miyake, M

    2017-01-01

    A mixture of oppositely charged polymer and surfactants changes the solubilized state, having a complex precipitation region at the composition of electric neutralization. This complex behavior has been applied to surface modification in the fields of health care and cosmetic products such as conditioning shampoos, as a dilution-deposition system in which the polymer/surfactant mixture at the higher surfactant concentration precipitates the insoluble complex by dilution. A large number of studies over many years have revealed the basic coacervation behavior and physicochemical properties of complexes. However, the mechanism by which a precipitated complex performs surface modification is not well understood. The precipitation region and the morphology of precipitated complex that are changed by molecular structure and additives affect the performance. Hydrophilic groups such as the EO unit in polymers and surfactants, the mixing of nonionic or amphoteric surfactant and nonionic polymer, and the addition of low polar solvent influence the complex precipitation region. Furthermore, the morphology of precipitated complex is formed by crosslinking and aggregating among polymers in the dilution process, and characterizes the performance of products. The polymer chain density in precipitated complex is determined by the charges of both the polymer and surfactant micelle and the conformation of polymer. As a result, the morphology of precipitated complexes is changed from a closely packed film to looser meshes, and/or to small particles, and it is possible for the morphology to control the rheological properties and the amount of adsorbed silicone. In the future, further investigation of the relationships between the morphology and performance is needed.

  19. Rheological techniques for determining degradation of polylactic acid in bioresorbable medical polymer systems

    Science.gov (United States)

    Choong, Gabriel Y. H.; Parsons, Andrew J.; Grant, David M.; De Focatiis, Davide S. A.

    2015-05-01

    A method developed in the 1980s for the conversion of linear rheological data to molar mass distribution is revisited in the context of degradable polymers. The method is first applied using linear rheology for a linear polystyrene, for which all conversion parameters are known. A proof of principle is then carried out on four polycarbonate grades. Finally, preliminary results are shown on degradable polylactides. The application of this method to degrading polymer systems, and to systems containing nanofillers, is also discussed. This work forms part of a wider study of bioresorbable nanocomposites using polylactides, novel hydroxyapatite nanoparticles and tailored dispersants for medical applications.

  20. Hybrid Materials Prepared from Polymers and Self-assembled Systems by Physical Processes

    Institute of Scientific and Technical Information of China (English)

    Jean-Michel; Guenet

    2007-01-01

    1 Results A new type of hybrid materails prepared from ternary systems polymer/bicopper organic complex/solvent is presented.Each binary system displays differing types of behaviour: The polymer solutions produce thermoreversible gels while the bicopper organic complex (designated as CuS8) forms randomly-dispersed,self-assembling threads in organic solvents (See Fig.1(a),(b)).Fig.1 The CuS8 and ips thermoreversible gels Thermoreversible gels possess a fibrillar morphology with a typical mesh size ra...

  1. Conductive polymers for controlled release and treatment of central nervous system injury

    Science.gov (United States)

    Saigal, Rajiv

    As one of the most devastating forms of neurotrauma, spinal cord injury remains a challenging clinical problem. The difficulties in treatment could potentially be resolved by better technologies for therapeutic delivery. In order to develop new approaches to treating central nervous system injury, this dissertation focused on using electrically-conductive polymers, controlled drug release, and stem cell transplantation. We first sought to enhance the therapeutic potential of neural stem cells by electrically increasing their production of neurotrophic factors (NTFs), important molecules for neuronal cell survival, differentiation, synaptic development, plasticity, and growth. We fabricated a new cell culture device for growing neural stem cells on a biocompatible, conductive polymer. Electrical stimulation via the polymer led to upregulation of NTF production by neural stem cells. This approach has the potential to enhance stem cell function while avoiding the pitfalls of genetic manipulation, possibly making stem cells more viable as a clinical therapy. Seeing the therapeutic potential of conductive polymers, we extended our studies to an in vivo model of spinal cord injury (SCI). Using a novel fabrication and extraction technique, a conductive polymer was fabricated to fit to the characteristic pathology that follows contusive SCI. Assessed via quantitative analysis of MR images, the conductive polymer significantly reduced compression of the injured spinal cord. Further characterizing astroglial and neuronal response of injured host tissue, we found significant neuronal sparing as a result of this treatment. The in vivo studies also demonstrated improved locomotor recovery mediated by a conductive polymer scaffold over a non-conductive control. We next sought to take advantage of conductive polymers for local, electronically-controlled release of drugs. Seeking to overcome reported limitations in drug delivery via polypyrrole, we first embedded drugs in poly

  2. Ionic conductivities of solid polymer electrolyte/salt systems: Group-contribution method

    Energy Technology Data Exchange (ETDEWEB)

    Joo, Jae Ho; Bae, Young Chan [Division of Chemical Engineering and Molecular Thermodynamics Laboratory, Hanyang University, Seoul 133791 (Korea, Republic of)

    2006-06-19

    We establish a new group-contribution model based on the Nernst-Einstein equation in which the diffusion coefficient is derived from the modified double-lattice (MDL) model and the Debye-Huckel (DH) theory. The model includes the combinatorial energy contribution that is responsible for the revised Flory-Huggins entropy of mixing, the van der Waals energy contribution from dispersion, and the polar force and the specific energy contribution from hydrogen bonding. The Nernst-Einstein equation takes into account the mobility of the salt and the motion of the polymer host. To describe the segmental motion of the polymer chain, which is the well known conduction mechanism for solid polymer electrolyte (SPE) systems, the effective co-ordinated unit parameter is introduced. Our results show that good agreement is obtained upon comparison with experimental data of various PEO and salt systems in the interested ranges. (author)

  3. Soft Polymers for Building up Small and Smallest Blood Supplying Systems by Stereolithography.

    Science.gov (United States)

    Meyer, Wolfdietrich; Engelhardt, Sascha; Novosel, Esther; Elling, Burkhard; Wegener, Michael; Krüger, Hartmut

    2012-03-29

    Synthesis of a homologous series of photo-polymerizable α,w-polytetrahydrofuranether-diacrylate (PTHF-DA) resins is described with characterization by NMR, GPC, DSC, soaking and rheometrical measurements. The curing speeds of the resins are determined under UV light exposure. Young's modulus and tensile strength of fully cured resins show flexible to soft material attributes dependent on the molar mass of the used linear PTHF-diacrylates. Structuring the materials by stereo lithography (SL) and multiphoton polymerization (MPP) leads to tubes and bifurcated tube systems with a diameter smaller than 2 mm aimed at small to smallest supplying systems with capillary dimensions. WST-1 biocompatibility tests ofm polymer extracts show nontoxic characteristics of the adapted polymers after a washing process. Some polymers show shape memory effect (SME).

  4. Soft Polymers for Building up Small and Smallest Blood Supplying Systems by Stereolithography

    Directory of Open Access Journals (Sweden)

    Michael Wegener

    2012-03-01

    Full Text Available Synthesis of a homologous series of photo-polymerizable α,w-polytetrahydrofuranether-diacrylate (PTHF-DA resins is described with characterization by NMR, GPC, DSC, soaking and rheometrical measurements. The curing speeds of the resins are determined under UV light exposure. Young’s modulus and tensile strength of fully cured resins show flexible to soft material attributes dependent on the molar mass of the used linear PTHF-diacrylates. Structuring the materials by stereo lithography (SL and multiphoton polymerization (MPP leads to tubes and bifurcated tube systems with a diameter smaller than 2 mm aimed at small to smallest supplying systems with capillary dimensions. WST-1 biocompatibility tests ofm polymer extracts show nontoxic characteristics of the adapted polymers after a washing process. Some polymers show shape memory effect (SME.

  5. Theory of optical transitions in conjugated polymers. I. Ideal systems

    Energy Technology Data Exchange (ETDEWEB)

    Barford, William, E-mail: william.barford@chem.ox.ac.uk [Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ (United Kingdom); Marcus, Max [Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ (United Kingdom); Magdalen College, University of Oxford, Oxford OX1 4AU (United Kingdom)

    2014-10-28

    We describe a theory of linear optical transitions in conjugated polymers. The theory is based on three assumptions. The first is that the low-lying excited states of conjugated polymers are Frenkel excitons coupled to local normal modes, described by the Frenkel-Holstein model. Second, we assume that the relevant parameter regime is ℏω ≪ J, i.e., the adiabatic regime, and thus the Born-Oppenheimer factorization of the electronic and nuclear degrees of freedom is generally applicable. Finally, we assume that the Condon approximation is valid, i.e., the exciton-polaron wavefunction is essentially independent of the normal modes. Using these assumptions we derive an expression for an effective Huang-Rhys parameter for a chain (or chromophore) of N monomers, given by S(N) = S(1)/IPR, where S(1) is the Huang-Rhys parameter for an isolated monomer. IPR is the inverse participation ratio, defined by IPR = (∑{sub n}|Ψ{sub n}|{sup 4}){sup −1}, where Ψ{sub n} is the exciton center-of-mass wavefunction. Since the IPR is proportional to the spread of the exciton center-of-mass wavefunction, this is a key result, as it shows that S(N) decreases with chain length. As in molecules, in a polymer S(N) has two interpretations. First, ℏωS(N) is the relaxation energy of an excited state caused by its coupling to the normal modes. Second, S(N) appears in the definition of an effective Franck-Condon factor, F{sub 0v}(N) = S(N){sup v}exp ( − S(N))/v! for the vth vibronic manifold. We show that the 0 − 0 and 0 − 1 optical intensities are proportional to F{sub 00}(N) and F{sub 01}(N), respectively, and thus the ratio of the 0 − 1 to 0 − 0 absorption and emission intensities are proportional to S(N). These analytical results are checked by extensive DMRG calculations and found to be generally valid, particularly for emission. However, for large chain lengths higher-lying quasimomentum exciton states become degenerate with the lowest vibrational excitation of the

  6. Origin of organic matter in the early solar system. VII - The organic polymer in carbonaceous chondrites

    Science.gov (United States)

    Hayatsu, R.; Matsuoka, S.; Anders, E.; Scott, R. G.; Studier, M. H.

    1977-01-01

    Degradation techniques, including pyrolysis, depolymerization, and oxidation, were used to study the insoluble polymer from the Murchison C2 chondrite. Oxidation with Cr2O7(2-) or O2/UV led to the identification of 15 aromatic ring systems. Of 11 aliphatic acids identified, three dicarboxylic acids presumably came from hydroaromatic portions of the polymer, whereas eight monocarboxylic acids probably derive from bridging groups or ring substituents. Depolymerization with CF3COO4 yielded some of the same ring systems, as well as alkanes (C1 through C8) and alkenes (C2 through C8), alkyl (C1 through C5) benzenes and naphthalenes, and methyl- or dimethyl -indene, -indane, -phenol, -pyrrole, and -pyridine. All these compounds were detected below 200 C, and are therefore probably indigenous constituents. The properties of the meteoritic polymer were compared with the properties of a synthetic polymer produced by the Fischer-Tropsch reaction. It is suggested that the meteoritic polymer was also produced by surface catalysis.

  7. High Energy, Low Temperature Gelled Bi-Propellant Formulation for Long-Duration In-Space Propulsion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The use of gelled propellants for deep space planetary missions may enable adoption of high performance (Isp-vac>360 sec) propellant combinations that do not...

  8. Effect of gelling agents on shoot growth and multiple shoot formation of mangosteen

    Directory of Open Access Journals (Sweden)

    Sompong Te-chato

    2005-12-01

    Full Text Available Apomict seeds of mangosteen were cultured as a whole or half seed on MS medium supplemented with 5 mg/l 6-benzyladenine (BA. The medium was solidified with various gelling agents. After culture for 2 months, multiple shoot formation, morphological and physiological characters of the shoot were investigated. The results revealed that 1.5% agarose gave the highest seed forming shoot (98% and number of shoots per culture seed (20.7. Wounding the seed by sectioning into half promoted higher callus formation (47-88% in all gelling agents. Phytagel (0.17% resulted in the highest callus formation (100% and hyperhydric shoots (11-31%. Those shoots produced translucent, thin and brittle leaves and stems, and malformed stoma. Those leaves had the lowest content of chlorophyll a, b and total chlorophyll.

  9. Stabilization of green bodies via sacrificial gelling agent during electrophoretic deposition

    Science.gov (United States)

    Worsley, Marcus A.; Kuntz, Joshua D.; Rose, Klint A.

    2016-03-22

    In one embodiment, a method for electrophoretic deposition of a three-dimensionally patterned green body includes suspending a first material in a gelling agent above a patterned electrode of an electrophoretic deposition (EPD) chamber, and gelling the suspension while applying a first electric field to the suspension to cause desired patterning of the first material in a resulting gelation. In another embodiment, a ceramic, metal, or cermet includes a plurality of layers, wherein each layer includes a gradient in composition, microstructure, and/or density in an x-y plane oriented parallel to a plane of deposition of the plurality of layers along a predetermined distance in a z-direction perpendicular to the plane of deposition.

  10. Correlation of the protein structure and gelling properties in dried egg white products.

    Science.gov (United States)

    Handa, A; Hayashi, K; Shidara, H; Kuroda, N

    2001-08-01

    The relationship between protein structure and aggregation, as well as heat-induced gelling properties, of seven dried egg white (DEW) products was investigated. Strong correlations were found between average molecular weight and hydrophobicity plus surface SH groups of DEW-soluble protein aggregate (SPA). This suggests that hydrophobic interactions and disulfide bond formation between protein molecules were involved in the aggregation. The average molecular weight of DEW products with alkaline pHs was relatively higher than those with neutral pHs and the same degree of protein unfolding, probably because of more disulfide bond formation between protein molecules. In addition, strong correlations were found between hydrophobicity, surface SH groups plus average molecular weight of DEW-SPA, and physical properties of the gels from DEW products. These data indicated that controlling the aggregation of DEW proteins in the dry state is crucial to controlling the gelling properties of DEW.

  11. Optical coupling of bare optoelectronic components and flexographically printed polymer waveguides in planar optronic systems

    Science.gov (United States)

    Wang, Yixiao; Wolfer, Tim; Lange, Alex; Overmeyer, Ludger

    2016-05-01

    Large scale, planar optronic systems allowing spatially distributed functionalities can be well used in diverse sensor networks, such as for monitoring the environment by measuring various physical quantities in medicine or aeronautics. In these systems, mechanically flexible and optically transparent polymeric foils, e.g. polymethyl methacrylate (PMMA) and polyethylene terephthalate (PET), are employed as carrier materials. A benefit of using these materials is their low cost. The optical interconnections from light sources to light transmission structures in planar optronic systems occupy a pivotal position for the sensing functions. As light sources, we employ the optoelectronic components, such as edgeemitting laser diodes, in form of bare chips, since their extremely small structures facilitate a high integration compactness and ensure sufficient system flexibility. Flexographically printed polymer optical waveguides are deployed as light guiding structures for short-distance communication in planar optronic systems. Printing processes are utilized for this generation of waveguides to achieve a cost-efficient large scale and high-throughput production. In order to attain a high-functional optronic system for sensing applications, one of the most essential prerequisites is the high coupling efficiency between the light sources and the waveguides. Therefore, in this work, we focus on the multimode polymer waveguide with a parabolic cross-section and investigate its optical coupling with the bare laser diode. We establish the geometrical model of the alignment based on the previous works on the optodic bonding of bare laser diodes and the fabrication process of polymer waveguides with consideration of various parameters, such as the beam profile of the laser diode, the employed polymer properties of the waveguides as well as the carrier substrates etc. Accordingly, the optical coupling of the bare laser diodes and the polymer waveguides was simulated

  12. Rheological profiling of organogels prepared at critical gelling concentrations of natural waxes in a triacylglycerol solvent

    OpenAIRE

    Patel, Ashok; Babaahmadifooladi, Mehrnoosh; Lesaffer, Ans; Dewettinck, Koen

    2015-01-01

    The aim of this study was to use a detailed rheological characterization to gain new insights into the gelation behavior of natural waxes. To make a comprehensive case, six natural waxes (differing in the relative proportion of chemical components: hydrocarbons, fatty alcohols, fatty acids, and wax esters) were selected as organogelators to gel high-oleic sunflower oil. Flow and dynamic rheological properties of organogels prepared at critical gelling concentrations (Cg) of waxes were studied...

  13. Integrated lasers for biophotonic Lab-on-a-Chip systems in polymer

    DEFF Research Database (Denmark)

    Mappes, Timo; Vannahme, Christoph; Grossmann, Tobias

    2011-01-01

    Lab-on-a-Chip (LoC) systems enable biomedical or chemical testing for point-of-care analysis at the patient's bedside or in the field. Our work is focused on developing optical LoCs based on polymers by integrating microfluidic channels, optical waveguides, and miniaturized lasers on different pl...

  14. Compressive response of a glass-polymer system at various strain rates

    NARCIS (Netherlands)

    Fan, J.T.; Weerheijm, J.; Sluys, L.J.

    2016-01-01

    A glass-polymer system of a polyurethane elastomeric matrix with a single 3 mm-diameter glass particle was investigated using a split Hopkinson pressure bar (SHPB) setup for revealing the dynamic compressive mechanical response. This study produced the characteristics of the dynamic stress-strain re

  15. Novel routes to liquid-based self-healing polymer systems

    NARCIS (Netherlands)

    Mookhoek, S.D.

    2010-01-01

    Inspired by the current state-of-the-art and the progressing advancements in the field of self-healing materials, this thesis addresses several novel routes to advance the concept of liquid-based self-healing polymer systems. This thesis presents the concept and characterisation of a one-component s

  16. Order-disorder transitions in comb-like polymer-surfactant systems involving hydrogen bonds

    NARCIS (Netherlands)

    ten Brinke, G.; Huh, J; Ruokolainen, J.; Torkkeli, M.; Serimaa, R.; Ikkala, O.

    Conditions to obtain micro-phase separated morphologies in polymer-surfactant systems involving hydrogen bonds have been investigated using poly(4-vinyl pyridine) (P4VP) and surfactants capable of forming hydrogen bonds of different strength with the basic nitrogen of P4VP. Depending on the tail

  17. Novel routes to liquid-based self-healing polymer systems

    NARCIS (Netherlands)

    Mookhoek, S.D.

    2010-01-01

    Inspired by the current state-of-the-art and the progressing advancements in the field of self-healing materials, this thesis addresses several novel routes to advance the concept of liquid-based self-healing polymer systems. This thesis presents the concept and characterisation of a one-component

  18. Integrated lasers for biophotonic Lab-on-a-Chip systems in polymer

    DEFF Research Database (Denmark)

    Mappes, Timo; Vannahme, Christoph; Grossmann, Tobias

    2011-01-01

    Lab-on-a-Chip (LoC) systems enable biomedical or chemical testing for point-of-care analysis at the patient's bedside or in the field. Our work is focused on developing optical LoCs based on polymers by integrating microfluidic channels, optical waveguides, and miniaturized lasers on different pl...

  19. High temperature polymer fuel cells and their Interplay with fuel processing systems

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf; Qingfeng, Li; He, R.

    2003-01-01

    This paper reports recent results from our group on polymer electrolyte membrane fuel cells (PEMFC) based on the temperature resistant polymer polybenzimidazole (PBI), which allow working temperatures up to 200°C. The membrane has a water drag number near zero and need no water management at all....... The high working temperature allows for utilization of the excess heat for fuel processing. Moreover, it provides an excellent CO tolerance of several percent, and the system needs no purification of hydrogen from a reformer. Continuous service for over 6 months at 150°C has been demonstrated....

  20. Development of the computer-aided process planning (CAPP system for polymer injection molds manufacturing

    Directory of Open Access Journals (Sweden)

    J. Tepić

    2011-10-01

    Full Text Available Beginning of production and selling of polymer products largely depends on mold manufacturing. The costs of mold manufacturing have significant share in the final price of a product. The best way to improve and rationalize polymer injection molds production process is by doing mold design automation and manufacturing process planning automation. This paper reviews development of a dedicated process planning system for manufacturing of the mold for injection molding, which integrates computer-aided design (CAD, computer-aided process planning (CAPP and computer-aided manufacturing (CAM technologies.

  1. Cross-Linked Liquid Crystalline Systems From Rigid Polymer Networks to Elastomers

    CERN Document Server

    Broer, Dirk

    2011-01-01

    With rapidly expanding interest in liquid crystalline polymers and elastomers among the liquid crystal community, researchers are currently exploring the wide range of possible application areas for these unique materials, including optical elements on displays, tunable lasers, strain gauges, micro-structures, and artificial muscles. Written by respected scientists from academia and industry around the world, who are not only active in the field but also well-known in more traditional areas of research, "Cross-Linked Liquid Crystalline Systems: From Rigid Polymer Networks to Elastomers&qu

  2. Creep-Fatigue Relationsihps in Electroactive Polymer Systems and Predicted Effects in an Actuator Design

    Science.gov (United States)

    Vinogradov, Aleksandra M.; Ihlefeld, Curtis M.; Henslee, Issac

    2009-01-01

    The paper concerns the time-dependent behavior of electroactive polymers (EAP) and their use in advanced intelligent structures for space exploration. Innovative actuator design for low weight and low power valves required in small plants planned for use on the moon for chemical analysis is discussed. It is shown that in-depth understanding of cyclic loading effects observed through accelerated creep rates due to creep-fatigue interaction in polymers is critical in terms of proper functioning of EAP based actuator devices. In the paper, an overview of experimental results concerning the creep properties and cyclic creep response of a thin film piezoelectric polymer polyvinylidene fluoride (PVDF) is presented. The development of a constitutive creep-fatigue interaction model to predict the durability and service life of electroactive polymers is discussed. A novel method is proposed to predict damage accumulation and fatigue life of polymers under oyclic loading conditions in the presence of creep. The study provides a basis for ongoing research initiatives at the NASA Kennedy Space Center in the pursuit of new technologies using EAP as active elements for lunar exploration systems.

  3. Performance characteristics of a gelled-electrolyte valve-regulated lead-acid battery

    Indian Academy of Sciences (India)

    S K Martha; B Hariprakash; S A Gaffoor; A K Shukla

    2003-08-01

    12 V/25 AH gelled-electrolyte valve-regulated lead-acid batteries have been assembled in-house and their performance studied in relation to the absorptive glass-microfibre valve-regulated and flooded-electrolyte counterparts at various discharge rates and temperatures between –40°C and 40°C. Although the performance of the gelled-electrolyte valve-regulated battery is similar to both the absorptive glass-microfibre valve-regulated and flooded-electrolyte lead-acid batteries at temperatures above 0°C, it is superior to both the flooded-electrolyte and absorptive glass-microfibre valve-regulated lead-acid batteries at temperatures between 0°C and -40°C. The latter characteristic is attractive for expanding the application regime of valve-regulated lead-acid batteries. The corrosion rate for the positive grids in the gelled-electrolyte is also lower than both the flooded-electrolyte and absorptive glass-microfibre configurations.

  4. Molecular modeling in confined polymer and biomembrane systems

    Directory of Open Access Journals (Sweden)

    Jayeeta Ghosh

    2009-07-01

    Full Text Available The computational study of soft materials under confinement for bio- and nanotechnology still poses significantchallenges but has come a long way in the last decade. It is possible to realistically model and understand the fundamentalmechanisms which are at play if soft materials are confined to nanometer dimensions. Here, we present several recentexamples of such studies. Thin polymer films are abundantly used as friction modifiers or steric stabilizers. We show howsystematic modeling can shed light on the interplay between entropic and energetic interactions. Thin glassy films arecritical for the success of nanolithography. For that we have to understand the effect of confinement on the glass transitionbehavior in order to guarantee the stability and integrity of the lithographic masks. Simulations aim to understand the fundamental differences in the densities of states of glass formers in bulk and under confinement. With the advent of bionanotechnology the structure and phase behavior of lipid membranes as models for cellular membranes at the nano scale length is of importance due to implications in understanding the role of the lipids in biochemical membrane processes.

  5. DEVELOPMENT OF FAMOTIDINE FLOATING DRUG DELIVERY SYSTEM USING NATURAL POLYMERS

    Directory of Open Access Journals (Sweden)

    Mohammed Muqtader et al.

    2012-03-01

    Full Text Available In the present study,FDDS of Famotidine, a copmpetative inhibitor of histamine H2 receptors were prepared by using natural gums viz. xanthan gum and guar gum at different drug to gum ratio using sodium bicarbonate and citric acid as gas generating agents and lactose as diluent.FDDS tablets were prepared by wet granulation technique using PVP K30 as granulating agent. The prepared FDDS tablets were evaluated for its pre compression characteristics like bulk density, angle of repose, true density and compresibility index and post compression parameters such as hardness, friability, uniformity of drug content, in vitro floating studies, in vitro dissolution studies. The physical evaluation of all the formulations showed values within the prescribed limits for tests like hardness, friability and weight variation which indicate that the prepared tablets are of standard quality. The floating lag time of all the formulations was less than 10 minutes,All the formulations showed good matrix integrity and retarded the release of drug for 10 hours. Formulation X3 containg drug: xantahne gum ratio of 1:3 showed zero order kinetics, the IR spectroscopic studies indicated that the drug was compatible with the polymer and co-excipients and therefore can be a promising alternative to the existing dosage form.

  6. Further Improvement and System Integration of High Temperature Polymer Electrolyte Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Li, Qingfeng; Jensen, Jens Oluf

    with these compatible subunits. The main goal of the project is a 2kWel HT-PEMFC stack operating in a temperature range of 150-200°C, with a single cell performance target of 0.7 A/cm² at a cell voltage around 0.6 V. The target durability is more than 5,000 hours. A hydrocarbon reformer and a catalytic burner...... are to be developed and integrated with the stack. The key issue of the project is development and improvement of the temperature-resistant polymer membranes with respect to durability, conductivity, mechanical and other properties. For this purpose, basic polymers will be first synthesized and optimized. Different...... routes to functionalize the polymers will be explored to increate proton conductivity. By the development of advanced materials, demonstration of the high temperature PEMFC stack and integration of such a system, FURIM is expected to sufficiently promote the commercialisation of the fuel cell technology...

  7. Formulation of gastroretentive floating drug delivery system using hydrophilic polymers and its in vitro characterization

    Directory of Open Access Journals (Sweden)

    Venkata Srikanth Meka

    2014-04-01

    Full Text Available The aim of the present research is to formulate and evaluate the gastroretentive floating drug delivery system of antihypertensive drug, propranolol HCl. Gastroretentive floating tablets (GRFT were prepared by using a synthetic hydrophilic polymer polyethylene oxide of different grades such as PEO WSR N-12 K and PEO 18 NF as release retarding polymers and calcium carbonate as gas generating agent. The GRFT were compressed by direct compression strategy and the tablets were evaluated for physico-chemical properties, in vitro buoyancy, swelling studies, in vitro dissolution studies and release mechanism studies. From the dissolution and buoyancy studies, F 9 was selected as an optimized formulation. The optimized formulation followed zero order rate kinetics with non-Fickian diffusion mechanism. The optimized formulation was characterised with FTIR studies and observed no interaction between the drug and the polymers.

  8. Synthesis of End Functional Polymers via Atom Transfer Radical Polymerization in Immobilized Catalytic System

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Cross-linked polystyrene with azo-crown ether functional side chain (PSt-1, 10-dicarbonyl-3,6,9-trizaocylcodecane) was prepared under microwave irradiation and the structure was characterized through FT-IR and element analysis. The functionalized cross-linked polystyrene (cross-link degree, 3.5%) combining with immobilized catalyst system (CuBr and ethyl α-bromo-isobutyrate) can catalyze atom transfer radical polymerization of Styrene. Neat polymer products can be obtained then. Complex of La and the polymer end group (EBiB) was synthesized. The third order nonlinear optical property of the polymer-La complex was investigated and the structure was also characterized by FT-IR and XPS.

  9. Polymer Chemistry

    Science.gov (United States)

    Williams, Martha; Roberson, Luke; Caraccio, Anne

    2010-01-01

    This viewgraph presentation describes new technologies in polymer and material chemistry that benefits NASA programs and missions. The topics include: 1) What are Polymers?; 2) History of Polymer Chemistry; 3) Composites/Materials Development at KSC; 4) Why Wiring; 5) Next Generation Wiring Materials; 6) Wire System Materials and Integration; 7) Self-Healing Wire Repair; 8) Smart Wiring Summary; 9) Fire and Polymers; 10) Aerogel Technology; 11) Aerogel Composites; 12) Aerogels for Oil Remediation; 13) KSC's Solution; 14) Chemochromic Hydrogen Sensors; 15) STS-130 and 131 Operations; 16) HyperPigment; 17) Antimicrobial Materials; 18) Conductive Inks Formulations for Multiple Applications; and 19) Testing and Processing Equipment.

  10. Development of expert system for biobased polymer material selection: food packaging application.

    Science.gov (United States)

    Sanyang, M L; Sapuan, S M

    2015-10-01

    Biobased food packaging materials are gaining more attention owing to their intrinsic biodegradable nature and renewability. Selection of suitable biobased polymers for food packaging applications could be a tedious task with potential mistakes in choosing the best materials. In this paper, an expert system was developed using Exsys Corvid software to select suitable biobased polymer materials for packaging fruits, dry food and dairy products. If - Then rule based system was utilized to accomplish the material selection process whereas a score system was formulated to facilitate the ranking of selected materials. The expert system selected materials that satisfied all constraints and selection results were presented in suitability sequence depending on their scores. The expert system selected polylactic acid (PLA) as the most suitable material.

  11. Total phosphorus recovery in flowback fluids after gelled hydrocarbon fracturing fluid treatments

    Energy Technology Data Exchange (ETDEWEB)

    Fyten, G.; Houle, P.; Taylor, R.S. [Halliburton Energy Services, Calgary, AB (Canada); Stemler, P.S. [Petro-Canada Oil and Gas Inc., Calgary, AB (Canada); Lemieux, A. [Omnicon Consultants Inc., Calgary, AB (Canada)

    2006-07-01

    in the flowback fluid. The total phosphorus introduced by the gelled oil fracturing-fluid treatment could be present in the production fluid for significant periods of time depending on well production rates and hydraulic fracturing fluid treatment volume. Phosphonate ester oil gellants offer a notably lower ratio of volatile phosphorus to total phosphorus than phosphate esters. However, the ratio remains constant for both systems during flowback. The only exception is during initial flowback where a positive mass balance occurs and the ratio of volatile to total phosphorus doubles. 6 refs., 1 tab., 14 figs.

  12. A foaming process to prepare porous polymer membrane for lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Li, Z.H. [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan 411105 (China); New Energy and Materials Laboratory (NEML), Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433 (China)], E-mail: lzh69@xtu.edu.cn; Cheng, C.; Zhan, X.Y. [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan 411105 (China); Wu, Y.P. [New Energy and Materials Laboratory (NEML), Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433 (China)], E-mail: wuyp@fudan.edu.cn; Zhou, X.D. [State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237 (China)

    2009-07-15

    A foaming process was used to prepare porous polymer membranes (PPMs) based on poly(vinylidene diflouride-co-hexafluoropropylene) copolymer for lithium ion batteries. In this simple process, urea, the foaming agent, was decomposed into gases and was removed at an elevated temperature to get the porous structure within the polymer matrix. When the weight ratio of urea to P(VDF-HFP) is 5:6, the PPM presents the highest porosity, 70.2%, and the prepared gelled polymer electrolyte shows an ionic conductivity up to 1.43 x 10{sup -3} S cm{sup -1} at room temperature. This provides another way to prepare gelled polymer electrolytes easily for application in rechargeable lithium batteries.

  13. Optical manipulation with two beam traps in microfluidic polymer systems

    DEFF Research Database (Denmark)

    Khoury Arvelo, Maria; Matteucci, Marco; Sørensen, Kristian Tølbøl

    2015-01-01

    An optical trapping system with two opposing laser beams, also known as the optical stretcher, are naturally constructed inside a microfluidic lab-on-chip system. We present and compare two approaches to combine a simple microfluidic system with either waveguides directly written in the microflui...

  14. A study of the distribution of polymer/surfactant coacervate between solution and foam in archetypal shampoo systems.

    Science.gov (United States)

    Wilgus, Leigh Ann; Davis, Kathleen; Labeaud, Lauren; Gandolfi, Lisa; Lochhead, Robert Y

    2011-01-01

    The research reported here attempted to answer the question, "is the foam important in delivering coacervates from shampoos." In order to answer this question, we have measured the amount of polymer in the foam and in the liquid phases of several cationic polymer/anionic surfactant systems by gravimetry and by FTIR techniques. In all cases studied, we discovered that the concentration of solids and, especially the polymer, in the liquid phase and in the foam phase were essentially the same. We conclude that the foam is unlikely to be an important factor in the topical delivery of polymer/surfactant coacervates.

  15. Stiffness and Strength of Fiber Reinforced Polymer Composite Bridge Deck Systems

    OpenAIRE

    2002-01-01

    This research investigates two principal characteristics that are of primary importance in Fiber Reinforced Polymer (FRP) bridge deck applications: STIFFNESS and STRENGTH. The research was undertaken by investigating the stiffness and strength characteristics of the multi-cellular FRP bridge deck systems consisting of pultruded FRP shapes. A systematic analysis procedure was developed for the stiffness analysis of multi-cellular FRP deck systems. This procedure uses the Method of Elasti...

  16. Electrospinning of nanofibers from non-polymeric systems: polymer-free nanofibers from cyclodextrin derivatives.

    Science.gov (United States)

    Celebioglu, Asli; Uyar, Tamer

    2012-01-21

    High molecular weight polymers and high polymer concentrations are desirable for the electrospinning of nanofibers since polymer chain entanglements and overlapping are important for uniform fiber formation. Hence, the electrospinning of nanofibers from non-polymeric systems such as cyclodextrins (CDs) is quite a challenge since CDs are cyclic oligosaccharides. Nevertheless, in this study, we have successfully achieved the electrospinning of nanofibers from chemically modified CDs without using a carrier polymer matrix. Polymer-free nanofibers were electrospun from three different CD derivatives, hydroxypropyl-β-cyclodextrin (HPβCD), hydroxypropyl-γ-cyclodextrin (HPγCD) and methyl-β-cyclodextrin (MβCD) in three different solvent systems, water, dimethylformamide (DMF) and dimethylacetamide (DMAc). We observed that the electrospinning of these CDs is quite similar to polymeric systems in which the solvent type, the solution concentration and the solution conductivity are some of the key factors for obtaining uniform nanofibers. Dynamic light scattering (DLS) measurements indicated that the presence of considerable CD aggregates and the very high solution viscosity were playing a key role for attaining nanofibers from CD derivatives without the use of any polymeric carrier. The electrospinning of CD solutions containing urea yielded no fibers but only beads or splashes since urea caused a notable destruction of the self-associated CD aggregates in their concentrated solutions. The structural, thermal and mechanical characteristics of the CD nanofibers were also investigated. Although the CD derivatives are amorphous small molecules, interestingly, we observed that these electrospun CD nanofibers/nanowebs have shown some mechanical integrity by which they can be easily handled and folded as a free standing material.

  17. Electrospinning of nanofibers from non-polymeric systems: polymer-free nanofibers from cyclodextrin derivatives

    Science.gov (United States)

    Celebioglu, Asli; Uyar, Tamer

    2012-01-01

    High molecular weight polymers and high polymer concentrations are desirable for the electrospinning of nanofibers since polymer chain entanglements and overlapping are important for uniform fiber formation. Hence, the electrospinning of nanofibers from non-polymeric systems such as cyclodextrins (CDs) is quite a challenge since CDs are cyclic oligosaccharides. Nevertheless, in this study, we have successfully achieved the electrospinning of nanofibers from chemically modified CDs without using a carrier polymer matrix. Polymer-free nanofibers were electrospun from three different CD derivatives, hydroxypropyl-β-cyclodextrin (HPβCD), hydroxypropyl-γ-cyclodextrin (HPγCD) and methyl-β-cyclodextrin (MβCD) in three different solvent systems, water, dimethylformamide (DMF) and dimethylacetamide (DMAc). We observed that the electrospinning of these CDs is quite similar to polymeric systems in which the solvent type, the solution concentration and the solution conductivity are some of the key factors for obtaining uniform nanofibers. Dynamic light scattering (DLS) measurements indicated that the presence of considerable CD aggregates and the very high solution viscosity were playing a key role for attaining nanofibers from CD derivatives without the use of any polymeric carrier. The electrospinning of CD solutions containing urea yielded no fibers but only beads or splashes since urea caused a notable destruction of the self-associated CD aggregates in their concentrated solutions. The structural, thermal and mechanical characteristics of the CD nanofibers were also investigated. Although the CD derivatives are amorphous small molecules, interestingly, we observed that these electrospun CD nanofibers/nanowebs have shown some mechanical integrity by which they can be easily handled and folded as a free standing material.

  18. COMBINED MICROBIAL SURFACTANT-POLYMER SYSTEM FOR IMPROVED OIL MOBILITY AND CONFORMANCE CONTROL

    Energy Technology Data Exchange (ETDEWEB)

    Jorge Gabitto; Maria Barrufet

    2004-08-01

    Many domestic oil fields are facing abandonment even though they still contain two-thirds of their original oil. A significant number of these fields can yield additional oil using advanced oil recovery (AOR) technologies. To maintain domestic oil production at current levels, AOR technologies are needed that are affordable and can be implemented by independent oil producers of the future. Microbial enhanced oil recovery (MEOR) technologies have become established as cost-effective solutions for declining oil production. MEOR technologies are affordable for independent producers operating stripper wells and can be used to extend the life of marginal fields. The demonstrated versatility of microorganisms can be used to design advanced microbial systems to treat multiple production problems in complex, heterogeneous reservoirs. The proposed research presents the concept of a combined microbial surfactant-polymer system for advanced oil recovery. The surfactant-polymer system utilizes bacteria that are capable of both biosurfactant production and metabolically-controlled biopolymer production. This novel technology combines complementary mechanisms to extend the life of marginal fields and is applicable to a large number of domestic reservoirs. The research project described in this report is performed jointly by, Bio-Engineering Inc., a woman owned small business, Texas A&M University and Prairie View A&M University, a Historically Black College and University. This report describes the results of our laboratory work to grow microbial cultures and the work done on recovery experiments on core rocks. We have selected two bacterial strains capable of producing both surfactant and polymers. We have conducted laboratory experiments to determine under what conditions surfactants and polymers can be produced from one single strain. We have conduct recovery experiments to determine the performance of these strains under different conditions. Our results do not show a

  19. Flexible High-Energy Polymer-Electrolyte-Based Rechargeable Zinc-Air Batteries.

    Science.gov (United States)

    Fu, Jing; Lee, Dong Un; Hassan, Fathy Mohamed; Yang, Lin; Bai, Zhengyu; Park, Moon Gyu; Chen, Zhongwei

    2015-10-07

    A thin-film, flexible, and rechargeable zinc-air battery having high energy density is reported particularly for emerging portable and wearable electronic applications. This freeform battery design is the first demonstrated by sandwiching a porous-gelled polymer electrolyte with a freestanding zinc film and a bifunctional catalytic electrode film. The flexibility of both the electrode films and polymer electrolyte membrane gives great freedom in tailoring the battery geometry and performance.

  20. Self-healing polymer systems: Properties, synthesis and applications

    NARCIS (Netherlands)

    Garcia, S.J.; Fischer, H.R.

    2014-01-01

    After millions of years of evolution, nature has developed materials and systems based on the concept of damage management (healing) in order to extend survival possibilities. In the last 20 years, the dream of implementing this concept to engineering systems to extend service lifetime has become a

  1. Polymer-based stimuli-responsive recyclable catalytic systems for organic synthesis.

    Science.gov (United States)

    Zhang, Jingli; Zhang, Mingxi; Tang, Kangjian; Verpoort, Francis; Sun, Taolei

    2014-01-15

    The introduction of stimuli-responsive polymers into the study of organic catalysis leads to the generation of a new kind of polymer-based stimuli-responsive recyclable catalytic system. Owing to their reversible switching properties in response to external stimuli, these systems are capable of improving the mass transports of reactants/products in aqueous solution, modulating the chemical reaction rates, and switching the catalytic process on and off. Furthermore, their stimuli-responsive properties facilitate the separation and recovery of the active catalysts from the reaction mixtures. As a fascinating approach of the controllable catalysis, these stimuli-responsive catalytic systems including thermoresponsive, pH-responsive, chemo-mechano-chemical, ionic strength-responsive, and dual-responsive, are reviewed in terms of their nanoreactors and mechanisms.

  2. A polymer visualization system with accurate heating and cooling control and high-speed imaging.

    Science.gov (United States)

    Wong, Anson; Guo, Yanting; Park, Chul B; Zhou, Nan Q

    2015-04-23

    A visualization system to observe crystal and bubble formation in polymers under high temperature and pressure has been developed. Using this system, polymer can be subjected to a programmable thermal treatment to simulate the process in high pressure differential scanning calorimetry (HPDSC). With a high-temperature/high-pressure view-cell unit, this system enables in situ observation of crystal formation in semi-crystalline polymers to complement thermal analyses with HPDSC. The high-speed recording capability of the camera not only allows detailed recording of crystal formation, it also enables in situ capture of plastic foaming processes with a high temporal resolution. To demonstrate the system's capability, crystal formation and foaming processes of polypropylene/carbon dioxide systems were examined. It was observed that crystals nucleated and grew into spherulites, and they grew at faster rates as temperature decreased. This observation agrees with the crystallinity measurement obtained with the HPDSC. Cell nucleation first occurred at crystals' boundaries due to CO₂ exclusion from crystal growth fronts. Subsequently, cells were nucleated around the existing ones due to tensile stresses generated in the constrained amorphous regions between networks of crystals.

  3. Percolation phenomena in diffusion-controlled polymer matrix systems

    Institute of Scientific and Technical Information of China (English)

    徐铜文; 何炳林

    1997-01-01

    The controlled release of two kinds of drugs,5-fluorouracil (5-FU) and hydrocortisonum (Hydro.) loaded in poly(ethylene-vinylalcohol) (EVAL) was dealt with,of which 5-FU/EVAL and Hydro /EVAL matrix systems are composed.The results were analyzed using the pseudo-steady-diffusion models coupled with the fundamental concepts of percolation theory.The percolation thresholds for the two systems were calculated,which could indicate the contributions of pore diffusion and matrix diffusion.

  4. Preliminary Evaluations of Polymer-based Lithium Battery Electrolytes Under Development for the Polymer Electrolyte Rechargeable Systems Program

    Science.gov (United States)

    Manzo, Michelle A.; Bennett, William R.

    2003-01-01

    A component screening facility has been established at The NASA Glenn Research Center (GRC) to evaluate candidate materials for next generation, lithium-based, polymer electrolyte batteries for aerospace applications. Procedures have been implemented to provide standardized measurements of critical electrolyte properties. These include ionic conductivity, electronic resistivity, electrochemical stability window, cation transference number, salt diffusion coefficient and lithium plating efficiency. Preliminary results for poly(ethy1ene oxide)-based polymer electrolyte and commercial liquid electrolyte are presented.

  5. Economics of Direct Hydrogen Polymer Electrolyte Membrane Fuel Cell Systems

    Energy Technology Data Exchange (ETDEWEB)

    Mahadevan, Kathyayani

    2011-10-04

    Battelle's Economic Analysis of PEM Fuel Cell Systems project was initiated in 2003 to evaluate the technology and markets that are near-term and potentially could support the transition to fuel cells in automotive markets. The objective of Battelle?s project was to assist the DOE in developing fuel cell systems for pre-automotive applications by analyzing the technical, economic, and market drivers of direct hydrogen PEM fuel cell adoption. The project was executed over a 6-year period (2003 to 2010) and a variety of analyses were completed in that period. The analyses presented in the final report include: Commercialization scenarios for stationary generation through 2015 (2004); Stakeholder feedback on technology status and performance status of fuel cell systems (2004); Development of manufacturing costs of stationary PEM fuel cell systems for backup power markets (2004); Identification of near-term and mid-term markets for PEM fuel cells (2006); Development of the value proposition and market opportunity of PEM fuel cells in near-term markets by assessing the lifecycle cost of PEM fuel cells as compared to conventional alternatives used in the marketplace and modeling market penetration (2006); Development of the value proposition of PEM fuel cells in government markets (2007); Development of the value proposition and opportunity for large fuel cell system application at data centers and wastewater treatment plants (2008); Update of the manufacturing costs of PEM fuel cells for backup power applications (2009).

  6. Ion beam irradiation as a tool to improve the ionic conductivity in solid polymer electrolyte systems

    Energy Technology Data Exchange (ETDEWEB)

    Manjunatha, H., E-mail: h-manjunath@blr.amrita.edu; Kumaraswamy, G. N. [Department of Physics, Amrita Vishwa Vidyapeetham, Bengaluru-560 035 (India); Damle, R. [Department of Physics, Bangalore University, Bengaluru-560 056 (India)

    2016-05-06

    Solid polymer electrolytes (SPEs) have potential applications in solid state electronic and energy devices. The optimum conductivity of SPEs required for such applications is about 10{sup −1} – 10{sup −3} Scm{sup −1}, which is hard to achieve in these systems. It is observed that ionic conductivity of SPEs continuously increase with increasing concentration of inorganic salt in the host polymer. However, there is a critical concentration of the salt beyond which the conductivity of SPEs decreases due to the formation of ion pairs. In the present study, solid polymer thin films based on poly (ethylene oxide) (PEO) complexed with NaBr salt with different concentrations have been prepared and the concentration at which ion pair formation occurs in PEO{sub x}NaBr is identified. The microstructure of the SPE with highest ionic conductivity is modified by irradiating it with low energy O{sup +1} ion (100 keV) of different fluencies. It is observed that the ionic conductivity of irradiated SPEs increases by one order in magnitude. The increase in ionic conductivity may be attributed to the enhanced segmental motion of the polymer chains due to radiation induced micro structural modification.

  7. Novel smart yolk/shell polymer microspheres as a multiply responsive cargo delivery system.

    Science.gov (United States)

    Du, Pengcheng; Liu, Peng

    2014-03-25

    An effective strategy was developed to fabricate the novel dually thermo- and pH-responsive yolk/shell polymer microspheres as a drug delivery system (DDS) for the controlled release of anticancer drugs via two-stage distillation precipitation polymerization and seed precipitation polymerization. Their pH-induced thermally responsive polymer shells act as a smart "valve" to adjust the diffusion of the loaded drugs in/out of the polymer containers according to the body environments, while the movable P(MAA-co-EGDMA) cores enhance the drug loading capacity for the anticancer drug doxorubicin hydrochloride (DOX). The yolk/shell polymer microspheres show a low leakage at high pH values but significantly enhanced release at lower pH values equivalent to the tumor body fluid environments at human body temperature, exhibiting the apparent tumor-environment-responsive controlled "on-off" drug release characteristics. Meanwhile, the yolk/shell microspheres expressed very low in vitro cytotoxicity on HepG2 cells. Consequently, their precise tumor-environment-responsive drug delivery performance and high drug loading capacity offer promise for tumor therapy.

  8. A multiple unit floating drug delivery system of piroxicam using eudragit polymer

    Directory of Open Access Journals (Sweden)

    Kale R

    2007-01-01

    Full Text Available A floating drug delivery system of piroxicam in the form of microspheres was prepared using an enteric polymer and emulsification solvent-evaporation method. The microspheres remained buoyant continuously over the surface of acidic media containing surfactant for a period of 8-12 h in vitro . Differential scanning calorimetry and X-ray diffraction studies showed that drug incorporated in the outer shell of the polymer was completely amorphous. Scanning electron micrographs indicated that the microsphere is perfect sphere with an internal hollow cavity enclosed by a rigid shell of polymer. The micromeritic properties of microspheres were found to be much improved compared with original drug crystals. The in vitro drug release behavior of the floating microspheres was characterized as an enteric property. Polymer being soluble above pH 7.0, the drug release rates from microspheres changed dramatically above and below pH 7.0. At intestinal pH the drug release was faster and continuous as compared to the amount released at gastric pH.

  9. Ion beam irradiation as a tool to improve the ionic conductivity in solid polymer electrolyte systems

    Science.gov (United States)

    Manjunatha, H.; Damle, R.; Kumaraswamy, G. N.

    2016-05-01

    Solid polymer electrolytes (SPEs) have potential applications in solid state electronic and energy devices. The optimum conductivity of SPEs required for such applications is about 10-1 - 10-3 Scm-1, which is hard to achieve in these systems. It is observed that ionic conductivity of SPEs continuously increase with increasing concentration of inorganic salt in the host polymer. However, there is a critical concentration of the salt beyond which the conductivity of SPEs decreases due to the formation of ion pairs. In the present study, solid polymer thin films based on poly (ethylene oxide) (PEO) complexed with NaBr salt with different concentrations have been prepared and the concentration at which ion pair formation occurs in PEOxNaBr is identified. The microstructure of the SPE with highest ionic conductivity is modified by irradiating it with low energy O+1 ion (100 keV) of different fluencies. It is observed that the ionic conductivity of irradiated SPEs increases by one order in magnitude. The increase in ionic conductivity may be attributed to the enhanced segmental motion of the polymer chains due to radiation induced micro structural modification.

  10. High-density cell systems incorporating polymer microspheres as microenvironmental regulators in engineered cartilage tissues.

    Science.gov (United States)

    Solorio, Loran D; Vieregge, Eran L; Dhami, Chirag D; Alsberg, Eben

    2013-06-01

    To address the significant clinical need for tissue-engineered therapies for the repair and regeneration of articular cartilage, many systems have recently been developed using bioactive polymer microspheres as regulators of the chondrogenic microenvironment within high-density cell cultures. In this review, we highlight various densely cellular systems utilizing polymer microspheres as three-dimensional (3D) structural elements within developing engineered cartilage tissue, carriers for cell expansion and delivery, vehicles for spatiotemporally controlled growth factor delivery, and directors of cell behavior via regulation of cell-biomaterial interactions. The diverse systems described herein represent a shift from the more traditional tissue engineering approach of combining cells and growth factors within a biomaterial scaffold, to the design of modular systems that rely on the assembly of cells and bioactive polymer microspheres as building blocks to guide the creation of articular cartilage. Cell-based assembly of 3D microsphere-incorporated structures represents a promising avenue for the future of tissue engineering.

  11. Classification of stimuli-responsive polymers as anticancer drug delivery systems.

    Science.gov (United States)

    Taghizadeh, Bita; Taranejoo, Shahrouz; Monemian, Seyed Ali; Salehi Moghaddam, Zoha; Daliri, Karim; Derakhshankhah, Hossein; Derakhshani, Zaynab

    2015-02-01

    Although several anticancer drugs have been introduced as chemotherapeutic agents, the effective treatment of cancer remains a challenge. Major limitations in the application of anticancer drugs include their nonspecificity, wide biodistribution, short half-life, low concentration in tumor tissue and systemic toxicity. Drug delivery to the tumor site has become feasible in recent years, and recent advances in the development of new drug delivery systems for controlled drug release in tumor tissues with reduced side effects show great promise. In this field, the use of biodegradable polymers as drug carriers has attracted the most attention. However, drug release is still difficult to control even when a polymeric drug carrier is used. The design of pharmaceutical polymers that respond to external stimuli (known as stimuli-responsive polymers) such as temperature, pH, electric or magnetic field, enzymes, ultrasound waves, etc. appears to be a successful approach. In these systems, drug release is triggered by different stimuli. The purpose of this review is to summarize different types of polymeric drug carriers and stimuli, in addition to the combination use of stimuli in order to achieve a better controlled drug release, and it discusses their potential strengths and applications. A survey of the recent literature on various stimuli-responsive drug delivery systems is also provided and perspectives on possible future developments in controlled drug release at tumor site have been discussed.

  12. A Polymer Visualization System with Accurate Heating and Cooling Control and High-Speed Imaging

    Directory of Open Access Journals (Sweden)

    Anson Wong

    2015-04-01

    Full Text Available A visualization system to observe crystal and bubble formation in polymers under high temperature and pressure has been developed. Using this system, polymer can be subjected to a programmable thermal treatment to simulate the process in high pressure differential scanning calorimetry (HPDSC. With a high-temperature/high-pressure view-cell unit, this system enables in situ observation of crystal formation in semi-crystalline polymers to complement thermal analyses with HPDSC. The high-speed recording capability of the camera not only allows detailed recording of crystal formation, it also enables in situ capture of plastic foaming processes with a high temporal resolution. To demonstrate the system’s capability, crystal formation and foaming processes of polypropylene/carbon dioxide systems were examined. It was observed that crystals nucleated and grew into spherulites, and they grew at faster rates as temperature decreased. This observation agrees with the crystallinity measurement obtained with the HPDSC. Cell nucleation first occurred at crystals’ boundaries due to CO2 exclusion from crystal growth fronts. Subsequently, cells were nucleated around the existing ones due to tensile stresses generated in the constrained amorphous regions between networks of crystals.

  13. Manufacturing routes for disposable polymer blood diagnostic microfluidic systems

    DEFF Research Database (Denmark)

    Tosello, Guido; Griffiths, Christian; Azcarate, Sabino

    2008-01-01

    The future vision of multi - analysis point of care testing (POCT) shows a hand-held device that patients can use with an ease similar to current blood sugar test systems. Additionally the mobile instrument would require transfer of the measured test results wirelessly to the doctor’s office, thus...

  14. Ensete ventricosum (WELW. CHEESMAN: A CHEAP AND ALTERNATIVE GELLING AGENT FOR PINEAPPLE (Ananas comosus VAR. SMOOTH CAYENNE IN VITRO PROPAGATION

    Directory of Open Access Journals (Sweden)

    Biruk Ayenew

    2012-10-01

    Full Text Available Different mechanisms are tried so far to reduce the production cost of plant tissue culture through increasing multiplication rate and/or substituting expensive components for wider usage of the technology. Subsequently, replacing the most common gelling agent, agar, took an attention since higher proportion of media cost comes from it. Up to now different alternatives were tried though they have drawbacks due to their inherent chemical characteristics. Therefore the search for new alternatives like Enset ventricosum is important. Enset flour, ‘Bulla’, has been tried in this study for the first time to substitute agar and showed no significant difference for shoots number, root number, shoot height, leaf number and an associated fresh weight of the plantlets besides good gelling ability than Agar. Subsequently, ‘Bulla’ at 80g L-1 gelled well and gave 11.8 shoots with 0.95g and 13.33 roots having 1.37 cm length. This rate can also save up to 76 % cost of gelling though significant difference was found for root length of 3.23 cm with Agar, 8 g L-1. This indicates further study on biochemical and/ or hormonal activity and across crop genotypes to use ‘Bulla’ as a cheap alternative commercial gelling agent.

  15. Dissipated work in driven harmonic diffusive systems: General solution and application to stretching Rouse polymers

    Science.gov (United States)

    Speck, T.; Seifert, U.

    2005-02-01

    We study n-dimensional diffusive motion in an externally driven harmonic potential. For these systems the probability distribution of the applied work is a Gaussian. We give explicit expressions for its mean and variance, which are determined by a non-local integral kernel relating the time-derivatives of the applied forces. As illustrations, we specialize our results to dragging a colloidal particle through a viscous fluid and to stretching a Rouse polymer with different protocols.

  16. Experimental and theoretical aspects of studying themodynamics and mass transport in polymer-solvent systems

    Science.gov (United States)

    Davis, Peter Kennedy

    Mass transport and thermodynamics in polymer-solvent systems are two key areas of importance to the polymer industry. Numerous processes including polymerization reactors, membrane separations, foam production, devolatilization processes, film and coating drying, supercritical extractions, drug delivery, and even nano-technology require fundamental phase equilibria and diffusion information. Although such information is vital in equipment design and optimization, acquisition and modeling of these data are still in the research and development stages. This thesis is rather diverse as it addresses many realms of this broad research area. From high pressure to low pressure, experimental to theoretical, and infinite dilution to finite concentration, the thesis covers a wide range of topics that are of current importance to the industrial and academic polymer community. Chapter 1 discusses advances in the development of a new volumetric sorption pressure decay technique to make phase equilibrium and diffusion measurements in severe temperature-pressure environments. Chapter 2 provides the derivations and results of a new completely predictive Group Contribution Lattice Fluid Equation of State for multi-component polymer-solvent systems. The remaining four chapters demonstrate advances in the modeling of inverse gas chromatography (IGC) experiments. IGC has been used extensively of the last 50 years to make low pressure sorption and diffusion measurements at infinitely dilute and finite solvent concentrations. Chapter 3 proposes a new IGC experiment capable of obtaining ternary vapor-liquid equilibria in polymer-solvent-solvent systems. Also in that chapter, an extensive derivation is provided for a continuum model capable of describing the results of such an experiment. Chapter 4 presents new data collected on a packed column IGC experiment and a new model that can be used with those experimental data to obtain diffusion and partition coefficients. Chapter 5 addresses a

  17. COMBINED MICROBIAL SURFACTANT-POLYMER SYSTEM FOR IMPROVED OIL MOBILITY AND CONFORMANCE CONTROL

    Energy Technology Data Exchange (ETDEWEB)

    Jorge Gabitto; Maria Barrufet

    2005-08-01

    Many domestic oil fields are facing abandonment even though they still contain two-thirds of their original oil. A significant number of these fields can yield additional oil using advanced oil recovery (AOR) technologies. To maintain domestic oil production at current levels, AOR technologies are needed that are affordable and can be implemented by the independent oil producers of the future. Microbial enhanced oil recovery (MEOR) technologies have become established as cost-effective solutions for declining oil production. MEOR technologies are affordable for independent producers operating stripper wells and can be used to extend the life of marginal fields. The demonstrated versatility of microorganisms can be used to design advanced microbial systems to treat multiple production problems in complex, heterogeneous reservoirs. The proposed research presents the concept of a combined microbial surfactant-polymer system for advanced oil recovery. The surfactant-polymer system utilizes bacteria that are capable of both biosurfactant production and metabolically-controlled biopolymer production. This novel technology combines complementary mechanisms to extend the life of marginal fields and is applicable to a large number of domestic reservoirs. The research project described in this report was performed by Bio-Engineering Inc., a woman owned small business, Texas A&M University and Prairie View A&M University, a Historically Black College and University. This report describes the results of our laboratory work to grow microbial cultures, the work done on recovery experiments on core rocks, and computer simulations. We have selected two bacterial strains capable of producing both surfactant and polymers. We have conducted laboratory experiments to determine under what conditions surfactants and polymers can be produced from one single strain. We have conduct recovery experiments to determine the performance of these strains under different conditions. Our results

  18. Microcosmos the world of elementary particles : fictional discussions between Einstein, Newton, and Gell-Mann

    CERN Document Server

    Fritzsch, Harald

    2014-01-01

    This book provides a broad introduction into the field of particle physics for the general reader through virtual discussions among prominent physicists, Albert Einstein, Murray Gell-Mann, Issac Newton and a modern physicists. Matter is composed of quarks and electrons. The electrons interact with the atomic nuclei by the exchange of photons. The forces between the quarks are generated by the exchange of gluons, which leads to the confinement of the quarks. The weak bosons provide the weak forces among the leptons and quarks. The book is suitable for non-experts in physics. Readership: General readers, students and researchers in physics.

  19. Hydroponics gel as a new electrolyte gelling agent for alkaline zinc-air cells

    Science.gov (United States)

    Othman, R.; Basirun, W. J.; Yahaya, A. H.; Arof, A. K.

    The viability of hydroponics gel as a new alkaline electrolyte gelling agent is investigated. Zinc-air cells are fabricated employing 12 wt.% KOH electrolyte immobilised with hydroponics gel. The cells are discharged at constant currents of 5, 50 and 100 mA. XRD and SEM analysis of the anode plates after discharge show that the failure mode is due to the formation of zinc oxide insulating layers and not due to any side reactions between the gel and the plate or the electrolyte.

  20. Gelling preparation of starting materials for dry and wet syntheses of silicate minerals

    OpenAIRE

    Ikeda, Ko

    1985-01-01

    Gelling technique on the preparation of starting materials of silicates for both dry and wet (hydrothermal) syntheses has been fundamentally reinvestigated on the following components, SiO_2, Al_2O_3, Fe_2O_3, Cr_20_3, MgO, FeO, NiO and CaO by precipitating with excess ammonia water in ethyl alcohol solutions. On the basis of solubilities at each pH for each component, a general procedure for the preparation of starting materials including Na_2O and K_2O has been proposed.

  1. Influence of the concentration of locust bean gum on the gelling ability of whey peptic hydrolysates

    OpenAIRE

    Rocha, Cristina M. R.; Hilliou, L.; Teixeira, J. A.; M. P. Gonçalves

    2008-01-01

    The gelling ability of whey proteins can be changed by limited hydrolysis and by the presence of other components such as polysaccharides; depending on the environmental conditions it can either be improved or impaired. In this work the effect of LBG on the heat-set gelation of aqueous whey protein hydrolysates (10 % w/w) from pepsin was assessed at pH 7.0 by small deformation rheology. Whey protein concentrate (WPC) and hydrolysates with a degree of hydrolysis (DH) of 1.5, ...

  2. Quantum chemistry investigation of fluorinated polymer systems of industrial interest.

    Science.gov (United States)

    Mavroudakis, Evangelos; Cuccato, Danilo; Dossi, Marco; Comino, Giovanni; Moscatelli, Davide

    2014-01-09

    In this work, the free-radical polymerization (FRP) of widely used fluorinated monomers was investigated. Computational studies were conducted to assess the FRP kinetics of each binary copolymerization between vinylidene fluoride (VDF), hexafluoropropylene (HFP), and tetrafluoroethylene (TFE). More specifically, all calculations were performed using density functional theory (DFT), and the B3LYP level of theory was used to optimize structures and determine absolute minimum energy geometries, whereas the electronic energies were estimated using B3LYP/6-31G(d,p) as well as a higher level of theory, MPWB1K/6-31G(d,p). Transition state theory was employed to determine kinetic parameters according to the terminal model of copolymerization. The homopolymerization of VDF and all of its corresponding copolymerizations were investigated by taking into account every possible propagation reaction (head to head, head to tail, tail to tail, head to monomer, tail to monomer, etc.) to estimate the Arrhenius parameters for each system. This study provides the estimation of a large set of rate coefficients, which gives detailed pictures of the specific copolymerization systems examined and is highly valuable to generate a comprehensive overview of the polymerization kinetics of relevant fluorinated monomers.

  3. Cure Reaction Kinetics of Low Pressure Sheet Molding Compound System Thickened by Crystalline Polymer

    Institute of Scientific and Technical Information of China (English)

    QIN Yan; LIU Haihua; HUANG Zhixiong; MEI Qilin

    2007-01-01

    Several kinetic models for unsaturated polyester cure reaction and some existing parameter estimation techniques of these models were introduced. Correlated kinetic parameters and kinetic equations of the autocatalytic empirical kinetic model of LPSMC system were determined by using isothermal DSC to scan the system which was thickened by crystalline polymer (PEG-MAH). Through using a serial curing degree of the system to validate the model, the experimental results were basically identical with the predictions of the autocatalytic empirical kinetic model. This model could provide a theoretical reference to the determination of molding techniques of low pressure SMC.

  4. Polymer electrolytes, problems, prospects, and promises

    Energy Technology Data Exchange (ETDEWEB)

    Nagasubramanian, G.; Boone, D.

    1995-07-01

    Ionically conducting polymer electrolytes have generated, in recent years, wide-spread interest as candidate materials for a number of applications including high energy density and power lithium batteries. In the early 70s the first measurements of ionic conductivity in polyethylene oxide (PEO)-salt complexes were carried out. However, Armand was the first one to realize potential of these complexes (polymer-salt complexes) as practical ionically conducting materials for use as electrolytes in lithium batteries. Subsequent research efforts identified the limitations and constraints of the polymer electrolytes. These limitations include poor ionic conductivity at RT (< 10{sup {minus}8} S/cm), low cation transport number (<0.2) etc. Several different approaches have been made to improving the ionic conductivity of the polymer electrolytes while retaining the flexibility, processibility, ease of handling and relatively low impact on the environment that polymers inherently possess. This paper- reviews evolution of polymer electrolytes from conventional PEO-LiX slat complexes to the more conducting polyphosphazene and copolymers, gelled electrolytes etc. We also review the various chemical approaches including modifying PEO to synthesizing complicated polymer architecture. In addition, we discuss effect of various lithium salts on the conductivity of PEO-based polymers. Charge/discharge and cycle life data of polymer cells containing oxide and chalcogenide cathodes and lithium (Li) anode are reviewed. Finally, future research directions to improve the electrolyte properties are discussed.

  5. Novel colon targeted drug delivery system using natural polymers

    Directory of Open Access Journals (Sweden)

    Ravi V

    2008-01-01

    Full Text Available A novel colon targeted tablet formulation was developed using pectin as carrier and diltiazem HCl and indomethacin as model drugs. The tablets were coated with inulin followed by shellac and were evaluated for average weight, hardness and coat thickness. In vitro release studies for prepared tablets were carried out for 2 h in pH 1.2 HCl buffer, 3 h in pH 7.4 phosphate buffer and 6 h in simulated colonic fluid. The drug release from the coated systems was monitored using UV/Vis spectroscopy. In vitro studies revealed that the tablets coated with inulin and shellac have limited the drug release in stomach and small intestinal environment and released maximum amount of drug in the colonic environment. The study revealed that polysaccharides as carriers and inulin and shellac as a coating material can be used effectively for colon targeting of both water soluble and insoluble drugs.

  6. THE USE OF POLYMERS IN RADIOACTIVE WASTE PROCESSING SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Skidmore, E.; Fondeur, F.

    2013-04-15

    The Savannah River Site (SRS), one of the largest U.S. Department of Energy (DOE) sites, has operated since the early 1950s. The early mission of the site was to produce critical nuclear materials for national defense. Many facilities have been constructed at the SRS over the years to process, stabilize and/or store radioactive waste and related materials. The primary materials of construction used in such facilities are inorganic (metals, concrete), but polymeric materials are inevitably used in various applications. The effects of aging, radiation, chemicals, heat and other environmental variables must therefore be understood to maximize service life of polymeric components. In particular, the potential for dose rate effects and synergistic effects on polymeric materials in multivariable environments can complicate compatibility reviews and life predictions. The selection and performance of polymeric materials in radioactive waste processing systems at the SRS are discussed.

  7. The chemical and mechanical behaviors of polymer / reactive metal systems under high strain rates

    Science.gov (United States)

    Shen, Yubin

    As one category of energetic materials, impact-initiated reactive materials are able to release a high amount of stored chemical energy under high strain rate impact loading, and are used extensively in civil and military applications. In general, polymers are introduced as binder materials to trap the reactive metal powders inside, and also act as an oxidizing agent for the metal ingredient. Since critical attention has been paid on the metal / metal reaction, only a few types of polymer / reactive metal interactions have been studied in the literature. With the higher requirement of materials resistant to different thermal and mechanical environments, the understanding and characterization of polymer / reactive metal interactions are in great demand. In this study, PTFE (Polytetrafluoroethylene) 7A / Ti (Titanium) composites were studied under high strain rates by utilizing the Taylor impact and SHPB tests. Taylor impact tests with different impact velocities, sample dimensions and sample configurations were conducted on the composite, equipped with a high-speed camera for tracking transient images during the sudden process. SHPB and Instron tests were carried out to obtain the stress vs. strain curves of the composite under a wide range of strain rates, the result of which were also utilized for fitting the constitutive relations of the composite based on the modified Johnson-Cook strength model. Thermal analyses by DTA tests under different flow rates accompanied with XRD identification were conducted to study the reaction mechanism between PTFE 7A and Ti when only heat was provided. Numerical simulations on Taylor impact tests and microstructural deformations were also performed to validate the constitutive model built for the composite system, and to investigate the possible reaction mechanism between two components. The results obtained from the high strain rate tests, thermal analyses and numerical simulations were combined to provide a systematic study on

  8. Wetting and dispersion in ceramic/polymer melt injection molding systems: Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Sacks, M.D.; Williams, J.W.; Batich, C.D.

    1986-11-01

    Research progress is reported in the areas of rheological characterization, mixing/deagglomeration, ceramic/polymer interface modification, polymer matrix chemistry, and microstructure characterization. (DLC)

  9. Interdigitated silver-polymer-based antibacterial surface system activated by oligodynamic iontophoresis - an empirical characterization study.

    Science.gov (United States)

    Shirwaiker, Rohan A; Wysk, Richard A; Kariyawasam, Subhashinie; Voigt, Robert C; Carrion, Hector; Nembhard, Harriet Black

    2014-02-01

    There is a pressing need to control the occurrences of nosocomial infections due to their detrimental effects on patient well-being and the rising treatment costs. To prevent the contact transmission of such infections via health-critical surfaces, a prophylactic surface system that consists of an interdigitated array of oppositely charged silver electrodes with polymer separations and utilizes oligodynamic iontophoresis has been recently developed. This paper presents a systematic study that empirically characterizes the effects of the surface system parameters on its antibacterial efficacy, and validates the system's effectiveness. In the first part of the study, a fractional factorial design of experiments (DOE) was conducted to identify the statistically significant system parameters. The data were used to develop a first-order response surface model to predict the system's antibacterial efficacy based on the input parameters. In the second part of the study, the effectiveness of the surface system was validated by evaluating it against four bacterial species responsible for several nosocomial infections - Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Enterococcus faecalis - alongside non-antibacterial polymer (acrylic) control surfaces. The system demonstrated statistically significant efficacy against all four bacteria. The results indicate that given a constant total effective surface area, the system designed with micro-scale features (minimum feature width: 20 μm) and activated by 15 μA direct current will provide the most effective antibacterial prophylaxis.

  10. Oxygen Compatibility of Brass-Filled PTFE Compared to Commonly Used Fluorinated Polymers for Oxygen Systems

    Science.gov (United States)

    Herald, Stephen D.; Frisby, Paul M.; Davis, Samuel Eddie

    2009-01-01

    Safe and reliable seal materials for high-pressure oxygen systems sometimes appear to be extinct species when sought out by oxygen systems designers. Materials that seal well are easy to find, but these materials are typically incompatible with oxygen, especially in cryogenic liquid form. This incompatibility can result in seals that leak, or much worse, seals that easily ignite and burn during use. Materials that are compatible with oxygen are easy to find, such as the long list of compatible metals, but these metallic materials are limiting as seal materials. A material that seals well and is oxygen compatible has been the big game in the designer's safari. Scientists at the Materials Combustion Research Facility (MCRF), part of NASA/Marshall Space Flight Center (MSFC), are constantly searching for better materials and processes to improve the safety of oxygen systems. One focus of this effort is improving the characteristics of polymers used in the presence of an oxygen enriched environment. Very few systems can be built which contain no polymeric materials; therefore, materials which have good impact resistance, low heat of combustion, high auto-ignition temperature and that maintain good mechanical properties are essential. The scientists and engineers at the Materials Combustion Research Facility, in cooperation with seal suppliers, are currently testing a new formulation of polytetrafluoroethylene (PTFE) with Brass filler. This Brass-filled PTFE is showing great promise as a seal and seat material for high pressure oxygen systems. Early research has demonstrated very encouraging results, which could rank this material as one of the best fluorinated polymers ever tested. This paper will compare the data obtained for Brass-filled PTFE with other fluorinated polymers, such as TFE-Teflon (PTFE) , Kel-F 81, Viton A, Viton A-500, Fluorel , and Algoflon . A similar metal filled fluorinated polymer, Salox-M , was tested in comparison to Brass-filled PTFE to

  11. Enrichment of membrane proteins by partitioning in detergent/polymer aqueous two-phase systems.

    Science.gov (United States)

    Everberg, Henrik; Gustavasson, Niklas; Tjerned, Folke

    2008-01-01

    Methods that combine efficient solubilization with enrichment of proteins and intact protein complexes are of central interest in current membrane proteomics. We have developed methods based on nondenaturing detergent extraction of yeast mitochondrial membrane proteins followed by enrichment of hydrophobic proteins in aqueous two-phase system. Combining the zwitterionic detergent Zwittergent 3-10 and the nonionic detergent Triton X-114 results in a complementary solubilization of proteins, which is similar to that of the anionic detergent sodium dodecyl sulfate (SDS) but with the important advantage of being nondenaturing. Detergent/polymer two-phase system partitioning offers removal of soluble proteins that can be further improved by manipulation of the driving forces governing protein distribution between the phases. Integral and peripheral membrane protein subunits from intact membrane protein complexes partition to the detergent phase while soluble proteins are found in the polymer phase. An optimized solubilization protocol is presented in combination with detergent/polymer two-phase partitioning as a mild and efficient method for initial enrichment of membrane proteins and membrane protein complexes in proteomic studies.

  12. Prediction of intracellular storage polymers using quantitative image analysis in enhanced biological phosphorus removal systems.

    Science.gov (United States)

    Mesquita, Daniela P; Leal, Cristiano; Cunha, Jorge R; Oehmen, Adrian; Amaral, A Luís; Reis, Maria A M; Ferreira, Eugénio C

    2013-04-03

    The present study focuses on predicting the concentration of intracellular storage polymers in enhanced biological phosphorus removal (EBPR) systems. For that purpose, quantitative image analysis techniques were developed for determining the intracellular concentrations of PHA (PHB and PHV) with Nile blue and glycogen with aniline blue staining. Partial least squares (PLS) were used to predict the standard analytical values of these polymers by the proposed methodology. Identification of the aerobic and anaerobic stages proved to be crucial for improving the assessment of PHA, PHB and PHV intracellular concentrations. Current Nile blue based methodology can be seen as a feasible starting point for further enhancement. Glycogen detection based on the developed aniline blue staining methodology combined with the image analysis data proved to be a promising technique, toward the elimination of the need for analytical off-line measurements. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. High-stability polymer optical fiber with Rhodamine-doped cladding for fiber light systems

    Science.gov (United States)

    Jaramillo-Ochoa, L.; Narro-García, R.; Ocampo, M. A.; Quintero-Torres, R.

    2016-09-01

    In this work, the photodegradation of a polymer optical fiber with Rhodamine doped cladding as a function of illumination time and excitation intensity is presented. To show the effect of photodegradation on different bulk geometries and environments, the photodegradation from a dye doped preform and a PMMA thick film is also evaluated. The reversible and the irreversible degradation of the florescent material were quantified under an established excitation scheme. To this purpose, a four-level system to model the photodegradation rates and its relation with the population of the states is presented and it is used to justify a possible underlying mechanism. The obtained results suggest an increase of one order of magnitude in the stability (lifetime) of the polymer optical fiber with respect to the preform or the thick film geometry stability.

  14. Stimulation of immune systems by conjugated polymers and their potential as an alternative vaccine adjuvant

    Science.gov (United States)

    Gong, Hua; Xiang, Jian; Xu, Ligeng; Song, Xuejiao; Dong, Ziliang; Peng, Rui; Liu, Zhuang

    2015-11-01

    Recently, conjugated polymers have been widely explored in the field of nanomedicine. Careful evaluations of their biological effects are thus urgently needed. Hereby, we systematically evaluated the biological effects of different types of conjugated polymers on macrophages and dendritic cells (DCs), which play critical roles in the innate and adaptive immune systems, respectively. While naked poly-(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) exhibits a high level of cytotoxicity, polyethylene glycol (PEG) modified PEDOT:PSS (PEDOT:PSS-PEG) shows greatly reduced toxicity to various types of cells. To our surprise, PEGylation of PEDOT:PSS could obviously enhance the cellular uptake of these nanoparticles, leading to subsequent immune stimulations of both macrophages and DCs. In contrast, another type of conjugated polymer, polypyrrole (PPy), is found to be an inert material with neither significant cytotoxicity nor noticeable immune-stimulation activity. Interestingly, utilizing ovalbumin (OVA) as a model antigen, it is further uncovered in our ex vivo experiment that PEDOT:PSS-PEG may serve as an adjuvant to greatly enhance the immunogenicity of OVA upon simple mixing. Our study on the one hand suggests the promise of developing novel nano-adjuvants based on conjugated polymers, and on the other hand highlights the importance of careful evaluations of the impacts of any new nanomaterials developed for nanomedicine on the immune systems.Recently, conjugated polymers have been widely explored in the field of nanomedicine. Careful evaluations of their biological effects are thus urgently needed. Hereby, we systematically evaluated the biological effects of different types of conjugated polymers on macrophages and dendritic cells (DCs), which play critical roles in the innate and adaptive immune systems, respectively. While naked poly-(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) exhibits a high level of cytotoxicity

  15. Modeling and Simulation of Ballistic Penetration of Ceramic-Polymer-Metal Layered Systems

    Directory of Open Access Journals (Sweden)

    J. D. Clayton

    2015-01-01

    Full Text Available Numerical simulations and analysis of ballistic impact and penetration by tungsten alloy rods into composite targets consisting of layers of aluminum nitride ceramic tile(s, polymer laminae, and aluminum backing are conducted over a range of impact velocities on the order of 1.0 to 1.2 km/s. Computational results for ballistic efficiency are compared with experimental data from the literature. Simulations and experiments both demonstrate a trend of decreasing ballistic efficiency with increasing impact velocity. Predicted absolute residual penetration depths often exceed corresponding experimental values. The closest agreement between model and experiment is obtained when polymer interfaces are not explicitly represented in the numerical calculations, suggesting that the current model representation of such interfaces may be overly compliant. The present results emphasize the importance of proper resolution of geometry and constitutive properties of thin layers and interfaces between structural constituents for accurate numerical evaluation of performance of modern composite protection systems.

  16. Poloxamer thermogel systems as medium for crystallization.

    Science.gov (United States)

    Cespi, Marco; Bonacucina, Giulia; Casettari, Luca; Mencarelli, Giovanna; Palmieri, Giovanni Filippo

    2012-03-01

    To prepare a thermoreversible gel system able to work as a medium for crystallization at around 20°C, allowing easy retrieval of crystals by simply decreasing the gel temperature. Lactose was selected has model substance for crystallization. Water solutions with different% of poloxamer 407, α-Lactose monohydrate, and ethanol were prepared and analysed by rheology to understand how the different components alter the gelling temperature. The systems with the required characteristics for lactose crystallization were prepared and the crystals recovered by cooling and then filtering the dispersion. Rheological analysis showed interaction between the poloxamer and lactose. Increasing the quantity of poloxamer or lactose lowered the gelation temperature while the addition of small amounts of ethanol had a modest effect on the same property. These data were used to identify the ideal concentration of the components in order to prepare a system matching the features of our purpose. Such system yielded high quality crystals, with well-defined geometry and narrow particle size distribution. Poloxamer is a very interesting polymer in that it is able to generate a reversible gelling medium from which crystals can be harvested by filtering, without the addition of any chemicals to promote the sol-gel transition.

  17. Development status of solid polymer electrolyte water electrolysis for manned spacecraft life support systems

    Science.gov (United States)

    Nuttall, L. J.; Titterington, W. A.

    1974-01-01

    Details of the design and system verification test results are presented for a six-man-rated oxygen generation system. The system configuration incorporates components and instrumentation for computer-controlled operation with automatic start-up/shutdown sequencing, fault detection and isolation, and with self-contained sensors and controls for automatic safe emergency shutdown. All fluid and electrical components, sensors, and electronic controls are designed to be easily maintainable under zero-gravity conditions. On-board component spares are utilized in the system concept to sustain long-term operation (six months minimum) in a manned spacecraft application. The system is centered on a 27-cell solid polymer electrolyte water electrolysis module which, combined with the associated system components and controls, forms a total system envelope 40 in. high, 40 in. wide, and 30 in. deep.

  18. The Gell-Mann - Okubo Mass Relation among Baryons from Fully-Dynamical, Mixed-Action Lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Konstantinos Orginos; Silas Beane; Martin Savage

    2007-10-01

    We explore the Gell-Mann - Okubo mass relation among the octet baryons using fully-dynamical, mixed-action (domain-wall on rooted-staggered) lattice QCD calculations at a lattice spacing of b {approx} 0.125 fm and pion masses of m{sub pi} {approx} 290 MeV, 350 MeV, 490 MeV and 590 MeV. Deviations from the Gell-Mann - Okubo mass relation are found to be small at each quark mass.

  19. Investigation of in situ gelling alginate formulations as a sustained release vehicle for co-precipitates of dextromethrophan and Eudragit S 100

    Directory of Open Access Journals (Sweden)

    Maghraby Gamal Mohamed El

    2014-03-01

    Full Text Available Alginate vehicles are capable of forming a gel matrix in situ when they come into contact with gastric medium in the presence of calcium ions. However, the gel structure is pH dependent and can break after gastric emptying, leading to dose dumping. The aim of this work was to develop modified in situ gelling alginate formulations capable of sustaining dextromethorphan release throughout the gastrointestinal tract. Alginate solution (2 %, m/m was used as a vehicle for the tested formulations. Solid matrix of the drug and Eudragit S 100 was prepared by dissolving the drug and polymer in acetone. The organic solvent was then evaporated and the deposited solid matrix was micronized, sieved and dispersed in alginate solution to obtain candidate formulations. The release behavior of dextromethorphan was monitored and evaluated in a medium simulating the gastric and intestinal pH. Drug-polymer compatibility and possible solid-state interactions suggested physical interaction through hydrogen bonding between the drug and the polymer. A significant decrease in the rate and extent of dextromethorphan release was observed with increasing Eudragit S 100 concentration in the prepared particles. Most formulations showed sustained release profiles similar to that of a commercial sustained-release liquid based on ion exchange resin. The release pattern indicated strict control of drug release both under gastric and intestinal conditions, suggesting the potential advantage of using a solid dispersion of drug-Eudragit S 100 to overcome the problem of dose dumping after the rupture of the pH dependent alginate gels

  20. Investigation of in situ gelling alginate formulations as a sustained release vehicle for co-precipitates of dextromethrophan and Eudragit S 100.

    Science.gov (United States)

    El Maghraby, Gamal Mohamed; Elzayat, Ehab Mostafa; Alanazi, Fars Kaed

    2014-03-01

    Alginate vehicles are capable of forming a gel matrix in situ when they come into contact with gastric medium in the presence of calcium ions. However, the gel structure is pH dependent and can break after gastric emptying, leading to dose dumping. The aim of this work was to develop modified in situ gelling alginate formulations capable of sustaining dextromethorphan release throughout the gastrointestinal tract. Alginate solution (2 %, m/m) was used as a vehicle for the tested formulations. Solid matrix of the drug and Eudragit S 100 was prepared by dissolving the drug and polymer in acetone. The organic solvent was then evaporated and the deposited solid matrix was micronized, sieved and dispersed in alginate solution to obtain candidate formulations. The release behavior of dextromethorphan was monitored and evaluated in a medium simulating the gastric and intestinal pH. Drug-polymer compatibility and possible solid-state interactions suggested physical interaction through hydrogen bonding between the drug and the polymer. A significant decrease in the rate and extent of dextromethorphan release was observed with increasing Eudragit S 100 concentration in the prepared particles. Most formulations showed sustained release profiles similar to that of a commercial sustained-release liquid based on ion exchange resin. The release pattern indicated strict control of drug release both under gastric and intestinal conditions, suggesting the potential advantage of using a solid dispersion of drug-Eudragit S 100 to overcome the problem of dose dumping after the rupture of the pH dependent alginate gels.

  1. Extraction, characterization and gelling behavior enhancement of pectins from the cladodes of Opuntia ficus indica.

    Science.gov (United States)

    Lefsih, Khalef; Delattre, Cédric; Pierre, Guillaume; Michaud, Philippe; Aminabhavi, Tejraj M; Dahmoune, Farid; Madani, Khodir

    2016-01-01

    Total Pectins Fraction (TPF) was extracted at room temperature from dried cladodes of Opuntia ficus indica. TPF is constituted of three pectic fractions WSP, CSP and ASP, which are made up of 66.6%, 44.3% and 81.1% (w/w) of galacturonic acid, respectively. The antioxidant ability of TPF increased with the concentration increasing. It scavenged hydroxyl radical by 90% and chelated 90% of ferrous ions at 5 g/L. FTIR study was carried out. Strong characteristic absorption peaks at 1,618 cm(-1) assigned to the vibration of COO(-) group of galacturonic acid. In the fingerprint region, we noticed three well-defined peaks at 1054, 1085, and 1,154 cm(-1) characteristic of pectic polysaccharides. TPF are non-gelling pectins. The co-crosslinking of TPF with carrageenan was carried out and the gelling behavior was successfully improved. Thermo-sensitive hydrogel was obtained with 82% of TPF and 18% of carrageenan (w/w).

  2. Evaluation of gelling agents on anther culture: response of two soybean cultivars

    Directory of Open Access Journals (Sweden)

    Milena Barcelos Cardoso

    2007-11-01

    Full Text Available Anthers of two soybean cultivars were cultured in B5 long basal culture media gelled with agarose or PhytagelTM. Cytological examinations of the anthers were carried out during the first 45 days of culture to assay the viability and developmental stage of microspores. Frequency of callus formation was recorded at 45 days of culture. The analysis of variance of the microspore viability assay showed significant Cultivar X Gelling Agent X Day of Culture interactions. The frequencies of viable microspores decreased significantly with time of culture, within each cultivar and gelling agent tested. The interaction Day X Cultivar was significant for the frequencies of binucleate symmetrical grains and multinucleate/multicellular structures. The effect of gelling agents on the frequency of binucleate symmetrical pollens grains and multinucleate/multicellular structures was not significant. About the frequencies of calli and embryogenic calli formed, a significant difference was detected between the cultivars (IAS5= 14.8% and BRS 133=6.6%. Gelling agents showed no effect over these frequencies.Anteras de duas cultivares de soja foram cultivadas em meio de cultura basal B5 longo gelificado com agarose ou Phytagel®. Análises citológicas das anteras foram conduzidas durante os primeiros 45 dias de cultura para avaliar a viabilidade e o estágio de desenvolvimento dos micrósporos. A freqüência de formação de calos foi analisada após 45 dias do início da cultura. A análise da variância da viabilidade do micrósporo mostrou interações significativas de Cultivar X Agente Gelificante X Dias de Cultura. As freqüências de grãos de pólen viáveis diminuíram significativamente com o tempo de cultura, dentro de cada cultivar e agente gelificante testado. A interação Dia X Cultivar foi significante para as freqüências de grãos de pólen binucleados simétricos e estruturas multinucleados/multicelulares. O efeito do agente gelificante na freq

  3. 10 Mb/s visible light transmission system using a polymer light-emitting diode with orthogonal frequency division multiplexing.

    Science.gov (United States)

    Le, Son T; Kanesan, T; Bausi, F; Haigh, P A; Rajbhandari, S; Ghassemlooy, Z; Papakonstantinou, I; Popoola, W O; Burton, A; Le Minh, H; Cacialli, F; Ellis, A D

    2014-07-01

    We present a newly designed polymer light-emitting diode with a bandwidth of ~350  kHz for high-speed visible light communications. Using this new polymer light-emitting diode as a transmitter, we have achieved a record transmission speed of 10  Mb/s for a polymer light-emitting diode-based optical communication system with an orthogonal frequency division multiplexing technique, matching the performance of single carrier formats using multitap equalization. For achieving such a high data-rate, a power pre-emphasis technique was adopted.

  4. Further Improvement and System Integration of High Temperature Polymer Electrolyte Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf; Li, Qingfeng

    and power management system, that are compatible with the HT-PEMFC; and (3) integration of the HT-PEMFC stack with these compatible subunits. The main goal of the project is a 2kWel HT-PEMFC stack operating in a temperature range of 120-220°C, with a single cell performance target of 0.7 A/cm² at a cell...... voltage around 0.6 V. The target durability is more than 5,000 hours. A hydrocarbon reformer and a catalytic burner are to be developed and integrated with the stack. The key issue of the project is development and improvement of the temperature-resistant polymer membranes with respect to durability......, conductivity, mechanical and other properties. For this purpose, basic polymers will be first synthesized and optimized. Different routes to functionalize the polymers will be explored to increate proton conductivity. By the development of advanced materials, demonstration of the high temperature PEMFC stack...

  5. Application of stochastic system identification to the study of the compliance of electroactive polymers.

    Science.gov (United States)

    Pillai, Priam V; Hunter, Ian W; Hernandez, Emanuel

    2011-02-01

    Electroactive polymers have shown promising applications as transducers that can mimic biological muscle. The modulus or the compliance of many of these devices can change significantly as they are actuated making these materials attractive for applications that require tunable stiffness. We have developed a dynamic mechanical analyzer that is capable of making in situ measurements of the dynamic compliance transfer function of conducting polymers as a function of an electrochemical stimulus. We do this by simultaneously applying a stochastic stress waveform over a potential waveform and calculating the compliance as it changes over the course of electrochemical excitation. Using these signals we can calculate the compliance transfer function between 0.1 and 100 Hz and the impulse response function with up to 3% variation in its parameters. These functions are then computed as charge is injected into the polymer and it is shown that the low frequency gain of the transfer function can change by 30%-40% in the electrochemical system tested.

  6. Strategies for interfacing inorganic nanocrystals with biological systems based on polymer-coating.

    Science.gov (United States)

    Palui, Goutam; Aldeek, Fadi; Wang, Wentao; Mattoussi, Hedi

    2015-01-01

    Interfacing inorganic nanoparticles and biological systems with the aim of developing novel imaging and sensing platforms has generated great interest and much activity. However, the effectiveness of this approach hinges on the ability of the surface ligands to promote water-dispersion of the nanoparticles with long term colloidal stability in buffer media. These surface ligands protect the nanostructures from the harsh biological environment, while allowing coupling to target molecules, which can be biological in nature (e.g., proteins and peptides) or exhibit specific photo-physical characteristics (e.g., a dye or a redox-active molecule). Amphiphilic block polymers have provided researchers with versatile molecular platforms with tunable size, composition and chemical properties. Hence, several groups have developed a wide range of polymers as ligands or micelle capsules to promote the transfer of a variety of inorganic nanomaterials to buffer media (including magnetic nanoparticles and semiconductor nanocrystals) and render them biocompatible. In this review, we first summarize the established synthetic routes to grow high quality nanocrystals of semiconductors, metals and metal oxides. We then provide a critical evaluation of the recent developments in the design, optimization and use of various amphiphilic copolymers to surface functionalize the above nanocrystals, along with the strategies used to conjugate them to target biomolecules. We finally conclude by providing a summary of the most promising applications of these polymer-coated inorganic platforms in sensor design, and imaging of cells and tissues.

  7. Lowest of AC-DC power output for electrostrictive polymers energy harvesting systems

    Science.gov (United States)

    Meddad, Mounir; Eddiai, Adil; Hajjaji, Abdelowahed; Guyomar, Daniel; Belkhiat, Saad; Boughaleb, Yahia; Chérif, Aida

    2013-11-01

    Advances in technology led to the development of electronic circuits and sensors with extremely low electricity consumption. At the same time, structural health monitoring, technology and intelligent integrated systems created a need for wireless sensors in hard to reach places in aerospace vehicles and large civil engineering structures. Powering sensors with energy harvesters eliminates the need to replace batteries on a regular basis. Scientists have been forced to search for new power source that are able to harvested energy from their surrounding environment (sunlight, temperature gradients etc.). Electrostrictive polymer belonging to the family of electro-active polymers, offer unique properties for the electromechanical transducer technology has been of particular interest over the last few years in order to replace conventional techniques such as those based on piezoelectric or electromagnetic, these materials are highly attractive for their low-density, with large strain capability that can be as high as two orders of magnitude greater than the striction-limited, rigid and fragile electroactive ceramics. Electrostrictive polymers sensors respond to vibration with an ac output signal, one of the most important objectives of the electronic interface is to realize the required AC-DC conversion. The goal of this paper is to design an active, high efficiency power doubler converter for electrostrictive polymers exclusively uses a fraction of the harvested energy to supply its active devices. The simulation results show that it is possible to obtain a maximum efficiency of the AC-DC converter equal to 80%. Premiliminary experimental measurements were performed and the results obtained are in good agreement with simulations.

  8. Nontemplate-driven polymers: clues to a minimal form of organization closure at the early stages of living systems.

    Science.gov (United States)

    Freire, Miguel Ángel

    2015-06-01

    The emergence of the first polymers played an essential role in the transition from the physicochemical to the biological domain, a perception that embodied many different world paradigms relying on only one primal polymer. However, biological complexity would have appeared with an increasing set of associated chemistries and molecular interactions of many different macromolecules. In agreement with this notion, here, the purpose is to focus specific attention on current knowledge of modern biochemistry of a set of widespread polymers likely present in the Last Universal Common Ancestor synthesized by nontemplate-driven reactions with references to their abiotic synthesis. The proposed overview describes the manner in which these polymers could have organized around two polymerization reaction cycles and integrated into a minimal organizational closure at the early stages of living systems, independently of template replication processes. This hypothesis could provide an alternative conceptual framework to evaluate a plausible scenario addressing the transition from nonliving to protocellular systems.

  9. Synthetic polyacrylate polymers as particulate intranasal vaccine delivery systems for the induction of mucosal immune response.

    Science.gov (United States)

    Zaman, Mehfuz; Simerska, Pavla; Toth, Istvan

    2010-04-01

    The nasal route as a site of vaccine delivery for both local and systemic effect is currently of considerable interest. The administration of vaccines to mucosal surfaces such as the nasopharynx associated lymphoid tissues confers many advantages since the nasal mucosa is a primary site through which most inhaled antigens are encountered. However, the success of intranasally delivered mucosal vaccines is limited by lack of effective vaccine formulations or delivery systems suitable for use in humans. This review provides a brief overview of the mucosal immune system at the nasal surface, enhancement techniques for induction of mucosal immune response after intranasal administration of particulate systems and an explanation of the inherent properties of polyacrylate polymer-based particulate systems that may facilitate mucosal immune responses.

  10. Automated sorting of polymer flakes: fluorescence labeling and development of a measurement system prototype.

    Science.gov (United States)

    Brunner, S; Fomin, P; Kargel, Ch

    2015-04-01

    The extensive demand and use of plastics in modern life is associated with a significant economical impact and a serious ecological footprint. The production of plastics involves a high energy consumption and CO2 emission as well as the large need for (limited) fossil resources. Due to the high durability of plastics, large amounts of plastic garbage is mounting in overflowing landfills (plus 9.6 million tons in Europe in the year 2012) and plastic debris is floating in the world oceans or waste-to-energy combustion releases even more CO2 plus toxic substances (dioxins, heavy metals) to the atmosphere. The recycling of plastic products after their life cycle can obviously contribute a great deal to the reduction of the environmental and economical impacts. In order to produce high-quality recycling products, mono-fractional compositions of waste polymers are required. However, existing measurement technologies such as near infrared spectroscopy show limitations in the sorting of complex mixtures and different grades of polymers, especially when black plastics are involved. More recently invented technologies based on mid-infrared, Raman spectroscopy or laser-aided spectroscopy are still under development and expected to be rather expensive. A promising approach to put high sorting purities into practice is to label plastic resins with unique combinations of fluorescence markers (tracers). These are incorporated into virgin resins during the manufacturing process at the ppm (or sub ppm) concentration level, just large enough that the fluorescence emissions can be detected with sensitive instrumentation but neither affect the visual appearance nor the mechanical properties of the polymers. In this paper we present the prototype of a measurement and classification system that identifies polymer flakes (mill material of a few millimeters size) located on a conveyor belt in real time based on the emitted fluorescence of incorporated markers. Classification performance

  11. Studies on a Foam System of Ultralow Interfacial Tension Applied in Daqing Oilfield after Polymer Flooding

    Directory of Open Access Journals (Sweden)

    Hong-sheng Liu

    2013-01-01

    Full Text Available In order to study the effects of oil displacement by a foam system of ultralow interfacial tension, the interfacial activities and foam properties of a nonionic gemini surfactant (DWS were investigated under Daqing Oilfield reservoir conditions. Injection methods and alternate cycle of the foam system were discussed here on the basis of results from core flow experiments. It was obtained that the surface tension of DWS was approximately 25 mN/m, and ultralow interfacial tension was reached between oil and DWS with a surfactant concentration between 0.05wt% and 0.4wt%. The binary system showed splendid foam performances, and the preferential surfactant concentration was 0.3wt% with a polymer concentration of 0.2wt%. When gas and liquid were injected simultaneously, flow control capability of the foam reached its peak at the gas-liquid ratio of 3 : 1. Enhanced oil recovery factor of the binary foam system exceeded 10% in a parallel natural cores displacement after polymer flooding.

  12. Polymers and formulation strategies of nanofibrous systems for drug delivery application and tissue engineering.

    Science.gov (United States)

    Sebe, I; Kállai-Szabó, B; Zelkó, R; Szabó, D

    2015-01-01

    During the last decade, the formulation of nanofibrous materials loaded with different drugs for biomedical applications has evoked considerable interest. The large specific surface area, the special micro- and macrostructure of fiber mats, the possibility for gradual release and site-specific local delivery of the active compounds lead to cytotoxicity decrease and enhancement of the therapeutic effect of drugs and implants. The present review details the different spinning techniques applied for the design of micro- and nanofibrous drug delivery systems. It furthermore deals with the use of various polymers that are capable for the formation of fiber scaffolds of various biomedical applications.

  13. Voltage-controlled accommodating IOL system using an ion polymer metal composite actuator.

    Science.gov (United States)

    Horiuchi, Tetsuya; Mihashi, Toshifumi; Fujikado, Takashi; Oshika, Tetsuro; Asaka, Kinji

    2016-10-03

    Surgeons treat cataracts by replacing the clouded lens with an intraocular lens (IOL), but patients are required to wear reading glasses for tasks requiring near vision. We suggest a new voltage-controlled accommodating IOL made of an ionic polymer metal composite (IPMC) actuator to change focus. An in vitro experiment was conducted where an actuator was placed inside the eye and moved with applied voltage. The lens attached to the actuator was deformed by its movement to change the patient's focus. The results showed that this system can accommodate a change of approximately 0.8 diopters under an applied voltage of ± 1.3 V.

  14. Conjugated-polymer-based energy-transfer systems for antimicrobial and anticancer applications.

    Science.gov (United States)

    Yuan, Huanxiang; Wang, Bing; Lv, Fengting; Liu, Libing; Wang, Shu

    2014-10-29

    Conjugated polymers (CPs) attract a lot of attention in sensing, imaging, and biomedical applications because of recent achievements that are highlighted in this Research News article. A brief review of recent progress in the application of CP-based energy-transfer systems in antimicrobial and anticancer treatments is provided. The transfer of excitation energy from CPs to photosensitizers leads to the generation of reactive oxygen species (ROS) that are able to efficiently kill pathogenic microorganisms and cancer cells in the surroundings. Both fluorescence resonance energy transfer (FRET) and bioluminescence energy transfer (BRET) modes are discussed.

  15. Gelucire Based In Situ Gelling Emulsions: A Potential Carrier for Sustained Stomach Specific Delivery of Gastric Irritant Drugs

    Directory of Open Access Journals (Sweden)

    Ashwin Saxena

    2013-01-01

    Full Text Available Non steroidal anti-inflammatory drugs (NSAIDs are commonly prescribed medications to the geriatric patients for the treatment of arthritis and other painful disorders. The major side effects of NSAIDs are related to their effects on the stomach and bowels. The present study concerns assessment of the potential of liquid in situ gelling emulsion formulations (emulgels as patient compliant stomach specific sustained release carrier for the delivery of highly gastric irritant drug, Piroxicam. Emulgels were prepared, without using any emulgent, by mixing different concentrations of molten Gelucire 39/01 with low viscosity sodium alginate solution prepared in deionized water at 50°C. CaCO3 was used as buoyancy imparting as well as crosslinking agent. Emulgels so prepared were homogenous, physically stable, and rapidly formed into buoyant gelled mass when exposed to simulated gastric fluid (SGF, pH 1.2. Drug release studies carried out in SGF revealed significant retardation (P<0.05 of Piroxicam release from emulgels compared to conventional in situ gelling formulations prepared without Gelucire 39/01. Pharmacodynamic studies carried out in albino rats revealed significantly increased analgesic/anti-inflammatory response from in situ emulgels compared to conventional in situ gelling formulations. Further, in vivo toxicity studies carried out in albino rats revealed no signs of gastric ulceration upon prolonged dosing.

  16. Deformation and fracture of emulsion-filled gels: Effect of gelling agent concentration and oil droplet size

    NARCIS (Netherlands)

    Sala, G.; Vliet, van T.; Cohen Stuart, M.A.; Velde, van de F.; Aken, van G.A.

    2009-01-01

    The effect of the ratio between the modulus of the oil droplets and that of the gel matrix (varied by changing gelling agent concentration and oil droplet size) on the large deformation properties of gelatine, ¿-carrageenan and whey protein isolate (WPI) gels was studied at different compression spe

  17. RCLED Optimization and Nonlinearity Compensation in a Polymer Optical Fiber DMT System

    Directory of Open Access Journals (Sweden)

    Pu Miao

    2016-09-01

    Full Text Available In polymer optical fiber (POF systems, the nonlinear transfer function of the resonant cavity light emitting diode (RCLED drastically degrades the communication performance. After investigating the characteristics of the RCLED nonlinear behavior, an improved digital look-up-table (LUT pre-distorter, based on an adaptive iterative algorithm, is proposed. Additionally, the system parameters, including the bias current, the average electrical power, the LUT size and the step factor are also jointly optimized to achieve a trade-off between the system linearity, reliability and the computational complexity. With the proposed methodology, both the operating point and efficiency of RCLED are enhanced. Moreover, in the practical 50 m POF communication system with the discrete multi-tone (DMT modulation, the bit error rate performance is improved by over 12 dB when RCLED is operating in the nonlinear region. Therefore, the proposed pre-distorter can both resist the nonlinearity and improve the operating point of RCLED.

  18. An oral oligonucleotide delivery system based on a thiolated polymer: Development and in vitro evaluation.

    Science.gov (United States)

    Martien, Ronny; Hoyer, Herbert; Perera, Glen; Schnürch, Andreas Bernkop

    2011-08-01

    The purpose of this study was to develop and evaluate an oral oligonucleotide delivery system based on a thiolated polymer/reduced glutathione (GSH) system providing a protective effect toward nucleases and permeation enhancement. A polycarbophil-cysteine conjugate (PCP-Cys) was synthesized. Enzymatic degradation of a model oligonucleotide by DNase I and within freshly collected intestinal fluid was investigated in the absence and presence of PCP-Cys. Permeation studies with PCP-Cys/GSH versus control were performed in vitro on Caco-2 cell monolayers and ex vivo on rat intestinal mucosa. PCP-Cys displayed 223 ± 13.8 μmol thiol groups per gram polymer. After 4h, 61% of the free oligonucleotides were degraded by DNase I and 80% within intestinal fluid. In contrast, less than 41% (DNase I) and 60% (intestinal fluid) were degraded in the presence of 0.02% (m/v) PCP-Cys. Permeation studies revealed an 8-fold (Caco-2) and 10-fold (intestinal mucosa) increase in apparent permeability compared to buffer control. Hence, this PCP-Cys/GSH system might be a promising tool for the oral administration of oligonucleotides as it allows a significant protection toward degrading enzymes and facilitates their transport across intestinal membranes.

  19. Cell microencapsulation with synthetic polymers.

    Science.gov (United States)

    Olabisi, Ronke M

    2015-02-01

    The encapsulation of cells into polymeric microspheres or microcapsules has permitted the transplantation of cells into human and animal subjects without the need for immunosuppressants. Cell-based therapies use donor cells to provide sustained release of a therapeutic product, such as insulin, and have shown promise in treating a variety of diseases. Immunoisolation of these cells via microencapsulation is a hotly investigated field, and the preferred material of choice has been alginate, a natural polymer derived from seaweed due to its gelling conditions. Although many natural polymers tend to gel in conditions favorable to mammalian cell encapsulation, there remain challenges such as batch to batch variability and residual components from the original source that can lead to an immune response when implanted into a recipient. Synthetic materials have the potential to avoid these issues; however, historically they have required harsh polymerization conditions that are not favorable to mammalian cells. As research into microencapsulation grows, more investigators are exploring methods to microencapsulate cells into synthetic polymers. This review describes a variety of synthetic polymers used to microencapsulate cells. © 2014 The Authors. Journal of Biomedical Materials Research Part A Published by Wiley Periodicals, Inc.

  20. Thermally responsive polymer systems for self-healing, reversible adhesion and shape memory applications

    Science.gov (United States)

    Luo, Xiaofan

    Responsive polymers are "smart" materials that are capable of performing prescribed, dynamic functions under an applied stimulus. In this dissertation, we explore several novel design strategies to develop thermally responsive polymers and polymer composites for self-healing, reversible adhesion and shape memory applications. In the first case described in Chapters 2 and 3, a thermally triggered self-healing material was prepared by blending a high-temperature epoxy resin with a thermoplastic polymer, poly(epsilon-caprolactone) (PCL). The initially miscible system undergoes polymerization induced phase separation (PIPS) during the curing of epoxy and yields a variety of compositionally dependent morphologies. At a particular PCL loading, the cured blend displays a "bricks-and-mortar" morphology in which epoxy exists as interconnected spheres ("bricks") within a continuous PCL matrix ("mortar"). A heat induced "bleeding" phenomenon was observed in the form of spontaneous wetting of all free surfaces by the molten PCL, and is attributed to the volumetric thermal expansion of PCL above its melting point in excess of epoxy brick expansion, which we term differential expansive bleeding (DEB). This DEB is capable of healing damage such as cracks. In controlled self-healing experiments, heating of a cracked specimen led to PCL bleeding from the bulk that yields a liquid layer bridging the crack gap. Upon cooling, a "scar" composed of PCL crystals was formed at the site of the crack, restoring a significant portion of mechanical strength. We further utilized DEB to enable strong and thermally-reversible adhesion of the material to itself and to metallic substrates, without any requirement for macroscopic softening or flow. After that, Chapters 4--6 present a novel composite strategy for the design and fabrication of shape memory polymer composites. The basic approach involves physically combining two or more functional components into an interpenetrating fiber

  1. COMIC AGENTS: FROM A POETIC TO AN ANTHROPOLOGICAL PARADIGM OF COMEDY (ARISTOTLE AND ALFRED GELL

    Directory of Open Access Journals (Sweden)

    ANNA KAWALEC

    2016-05-01

    Full Text Available Aristotle was concerned with the comedy genre as a kind of poetry. Its creators, the comic poets, interested him only marginally. This genological approach to its subject-matter dominated the theory and philosophy of art for subsequent centuries as evidenced by the subsequent elaborations of interpretations of Aristotle’s catharsis. The alternative approach focused instead on subjects as creators of art. As a consequence of the long-term development of anthropocentrism in the humanities, however, this approach took over. The “ performative turn” represents its more recent version. It allows one to interpret Poetics and other classical works not in the context of an object (comedy, but in the context of the acting subject. I claim that social anthropology further explores the concept of comedy and itself presumes it in its conceptual foundations and research approach. I elaborate the argument on the basis of the concept of the “spirit of comedy” coined by Alfred Gell .

  2. In situ gelling stimuli-sensitive block copolymer hydrogels for drug delivery.

    Science.gov (United States)

    He, Chaoliang; Kim, Sung Wan; Lee, Doo Sung

    2008-05-08

    Stimuli-sensitive block copolymer hydrogels, which are reversible polymer networks formed by physical interactions and exhibit a sol-gel phase-transition in response to external stimuli, have great potential in biomedical and pharmaceutical applications, especially in site-specific controlled drug-delivery systems. The drug may be mixed with a polymer solution in vitro and the drug-loaded hydrogel can form in situ after the in vivo administration, such as injection; therefore, stimuli-sensitive block copolymer hydrogels have many advantages, such as simple drug formulation and administration procedures, no organic solvent, site-specificity, a sustained drug release behavior, less systemic toxicity and ability to deliver both hydrophilic and hydrophobic drugs. Among the stimuli in the biomedical applications, temperature and pH are the most popular physical and chemical stimuli, respectively. The temperature- and/or pH-sensitive block copolymer hydrogels for biomedical applications have been extensively developed in the past decade. This review focuses on recent development of the preparation and application for drug delivery of the block copolymer hydrogels that respond to temperature, pH or both stimuli, including poly(N-substituted acrylamide)-based block copolymers, poloxamers and their derivatives, poly(ethylene glycol)-polyester block copolymers, polyelectrolyte-based block copolymers and the polyelectrolyte-modified thermo-sensitive block copolymers. In addition, the hydrogels based on other stimuli-sensitive block copolymers are discussed.

  3. Solid polymer electrolyte water electrolysis system development. [to generate oxygen for manned space station applications

    Science.gov (United States)

    1975-01-01

    Solid polymer electrolyte technology used in a water electrolysis system (WES) to generate oxygen and hydrogen for manned space station applications was investigated. A four-man rated, low pressure breadboard water electrolysis system with the necessary instrumentation and controls was fabricated and tested. A six man rated, high pressure, high temperature, advanced preprototype WES was developed. This configuration included the design and development of an advanced water electrolysis module, capable of operation at 400 psig and 200 F, and a dynamic phase separator/pump in place of a passive phase separator design. Evaluation of this system demonstrated the goal of safe, unattended automated operation at high pressure and high temperature with an accumulated gas generation time of over 1000 hours.

  4. Nanospray technology for an in situ gelling nanoparticulate powder as a wound dressing.

    Science.gov (United States)

    De Cicco, Felicetta; Porta, Amalia; Sansone, Francesca; Aquino, Rita P; Del Gaudio, Pasquale

    2014-10-01

    In the current study the feasibility of the novel nano spray drying technique for the production of stable nanoparticulate dry powder, able to gel when administered locally on a wound, is explored. Gentamicin sulphate (GS) was loaded into alginate/pectin nanoparticles as highly soluble (hygroscopic) model drug with wide range antibacterial agent for wound dressing. The influence of process variables, mainly spray mesh size and feed concentration, on particle size and morphology, powder wound fluid uptake ability and gelling rate, as well as hydrogel water vapour transmission at wound site were studied. Particles morphology was spherical with few exceptions as slightly corrugated particles when the larger nozzle was used. Production of spherical nanoparticles (d50 ∼ 350 nm) in good yield (82-92%) required 4 μm spray mesh whereas 7 μm mesh produced larger wrinkled particles. Nano spray-dried particles showed high encapsulation efficiency (∼ 80%), good flowability, high fluid uptake, fast gel formation (15 min) and proper adhesiveness to fill the wound site and to remove easily the formulation after use. Moreover, moisture transmission of the in situ formed hydrogel was between 95 and 90 g/m(2)/h, an optimum range to avoid wound dehydration or occlusion phenomena. Release of the encapsulated GS, monitored as permeation rate using Franz cells in simulated wound fluid (SWF) was related to particle size and gelling rate. Sustained permeation profiles were obtained achieving total permeation of the drug between 3 and 6 days. However, all nano spray-dried formulations presented a burst effect, suitable to prevent infection spreading at the beginning of the therapy. Antimicrobial tests against Staphylococcus aureus and Pseudomonas aeruginosa showed stronger and prolonged antimicrobial effect of the nanoparticles compared to pure GS both shortly after administration and over time (till 12 days).

  5. New formulation of in situ gelling Metolose-based liquid suppository.

    Science.gov (United States)

    Pásztor, E; Makó, A; Csóka, G; Fenyvesi, Zs; Benko, R; Prosszer, M; Marton, S; Antal, I; Klebovich, I

    2011-01-01

    An in situ gelling liquid suppository is liquid at room temperature but forms a gel at body temperature. In our work, Metolose® SM-4000 (methylcellulose) is studied that basically shows thermal gelation at 68°C (2%, w/w). The objective was to study the potency of different factors (concentration, pH, additives) to change the value of thermal gelation temperature (T (t)) for Metolose® to form an in situ gelling liquid suppository. We studied the effect of Metolose® concentration, pH, and salts (sodium chloride, potassium chloride, sodium hydrogen carbonate, and sodium monohydrogen phosphate) on T (t) by viscosimetry. To choose the appropriate compound, in vitro drug release was examined. Rectal safety test was performed on rats in vivo after 12-hour application. Increasing the Metolose® concentrations (0.5-4%, w/w), T (t) can be decreased, but it also altered the consistency of gel. pH does not affect the T (t). The water-soluble salts allowed reducing the gelation temperature to 37°C. Sodium monohydrogen phosphate in 4.5% concentration was found to be the most appropriate. The impact of examined factors on in vitro drug release of piroxicam from the in situ-formed gel was characterized according to Fickian diffusion. Metolose® and the chosen salt did not cause any morphological damage on the rectal tissues. According to our study, Metolose® has the physical and chemical potential to be used as base for liquid suppositories.

  6. Technical note: PaGELL v.1.5: A flexible parametric program for the Bayesian analysis of longevity data within the context of animal breeding.

    Science.gov (United States)

    Casellas, J; Brito, L C

    2017-10-01

    This technical note presents the program PaGELL v.1.5 (Parametric Genetic Evaluation of Lifespan in Livestock), a flexible software program to analyze (right-censored) longevity data in livestock populations, with a special emphasis on the genetic evaluation of the breeding stock. This software relies on a parametric generalization of the proportional hazard model; more specifically, the baseline hazard function follows a Weibull process and flexibility is gained by including an additional time-dependent effect with the number of change points defined by the user. The program can accommodate 3 different sources of variation (i.e., systematic, permanent environmental, and additive genetic effects) and both fixed and time-dependent patterns (only for systematic and permanent environmental effects). Analyses are performed within a Bayesian context by sampling from the joint posterior distribution of the model, and model fit can be easily determined by the calculation of the deviance information criterion. Although this software has already been used on field data sets, its performance has been double-checked on simulated data set, and results are presented in this technical note. PaGELL v.1.5 was written in Fortran 95 language and, after compiling with the GNU Fortran Compiler v.4.7 and later, it has been tested in Windows, Linux, and MacOS operating systems (both 32- and 64-bit platforms). This program is available at http://www.casellas.info/files/pageII.zip. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  7. A Tailor-Made Synthetic Polymer for Cell Encapsulation: Design Rationale, Synthesis, Chemical-Physics and Biological Characterizations.

    Science.gov (United States)

    Gerges, Irini; Tamplenizza, Margherita; Rossi, Eleonora; Tocchio, Alessandro; Martello, Federico; Recordati, Camilla; Kumar, Deepak; Forsyth, Nicholas R; Liu, Yang; Lenardi, Cristina

    2016-06-01

    This study presents a custom-made in situ gelling polymeric precursor for cell encapsulation. Composed of poly((2-hydroxyethyl)methacrylate-co-(3-aminopropyl)methacrylamide) (P(HEMA-co-APM) mother backbone and RGD-mimicking poly(amidoamine) (PAA) moiteis, the comb-like structured polymeric precursor is tailored to gather the advantages of the two families of synthetic polymers, i.e., the good mechanical integrity of PHEMA-based polymers and the biocompatibility and biodegradability of PAAs. The role of P(HEMA-co-APM) in the regulation of the chemico-physical properties of P(HEMA-co-APM)/PAA hydrogels is thoroughly investigated. On the basis of obtained results, namely the capability of maintaining vital NIH3T3 cell line in vitro for 2 d in a 3D cell culture, the in vivo biocompatibility in murine model for 16 d, and the ability of finely tuning mechanical properties and degradation kinetics, it can be assessed that P(HEMA-co-APM)/PAAs offer a cost-effective valid alternative to the so far studied natural polymer-based systems for cell encapsulation.

  8. Molecular systems under shock compression into the dense plasma regime: carbon dioxide and hydrocarbon polymers

    Science.gov (United States)

    Mattsson, Thomas R.; Cochrane, Kyle R.; Root, Seth; Carpenter, John H.

    2013-10-01

    Density Functional Theory (DFT) has proven remarkably accurate in predicting properties of matter under shock compression into the dense plasma regime. Materials where chemistry plays a role are of interest for many applications, including planetary science and inertial confinement fusion (ICF). As examples of systems where chemical reactions are important, and demonstration of the high fidelity possible for these both structurally and chemically complex systems, we will discuss shock- and re-shock of liquid carbon dioxide (CO2) in the range 100 to 800 GPa and shock compression of hydrocarbon polymers, including GDP (glow discharge polymer) which is used as an ablator in laser ICF experiments. Experimental results from Sandia's Z machine validate the DFT simulations at extreme conditions and the combination of experiment and DFT provide reliable data for evaluating existing and constructing future wide-range equations of state models for molecular compounds. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  9. Intranasal delivery of Norwalk virus-like particles formulated in an in situ gelling, dry powder vaccine.

    Science.gov (United States)

    Velasquez, Lissette S; Shira, Samantha; Berta, Alice N; Kilbourne, Jacquelyn; Medi, Babu M; Tizard, Ian; Ni, Yawei; Arntzen, Charles J; Herbst-Kralovetz, Melissa M

    2011-07-18

    The development of a vaccine to prevent norovirus infections has been focused on immunization at a mucosal surface, but has been limited by the low immunogenicity of self-assembling Norwalk virus-like particles (NV VLPs) delivered enterically or at nasal surfaces. Nasal immunization, which offers the advantage of ease of immunization, faces obstacles imposed by the normal process of mucociliary clearance, which limits residence time of applied antigens. Herein, we describe the use of a dry powder formulation (GelVac) of an inert in situ gelling polysaccharide (GelSite) extracted from Aloe vera for nasal delivery of NV VLP antigen. Powder formulations, with or without NV VLP antigen, were similar in structure in dry form or when rehydrated in simulated nasal fluids. Immunogenicity of the dry powder VLP formulation was compared to equivalent antigen/adjuvant liquid formulations in animals. For the GelVac powder, we observed superior NV-specific serum and mucosal (aerodigestive and reproductive tracts) antibody responses relative to liquid formulations. Incorporation of the TLR7 agonist gardiquimod in dry powder formulations did not enhance antibody responses, although its inclusion in liquid formulations did enhance VLP immunogenicity irrespective of the presence or absence of GelSite. We interpret these data as showing that GelSite-based dry powder formulations (1) stabilize the immunogenic structural properties of VLPs and (2) induce systemic and mucosal antibody titers which are equal or greater than those achieved by VLPs plus adjuvant in a liquid formulation. We conclude that in situ gelation of the GelVac dry powder formulation at nasal mucosal surfaces delays mucociliary clearance and thereby prolongs VLP antigen exposure to immune effector sites.

  10. 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.

  11. A comparative simulation study on three lattice systems for the phase separation of polymer-dispersed liquid crystals

    Indian Academy of Sciences (India)

    Y J Jeon; M Jamil; Hyo-Dong Lee; J T Rhee

    2008-09-01

    This article reports a comparative study of the phase separation process in a polymer-dispersed liquid crystal, based on a Metropolis Monte Carlo simulation study of three lattice systems. We propose a model for the different processes occurring in the formation of polymer-dispersed liquid crystals (PDLCs). The mechanism of PDLC is studied as a function of quench temperature, concentration and degree of polymerization of liquid crystals and polymers. The obtained resultant phase diagrams of the three systems are approximated and compared with the Flory–Huggins theory, and show a good agreement. It has been observed in the simulation results that among all the three systems, the 40 × 40 × 40 lattice showed the most accurate, reliable and stable results.

  12. Polymer-drug compatibility: a guide to the development of delivery systems for the anticancer agent, ellipticine.

    Science.gov (United States)

    Liu, Jubo; Xiao, Yuehua; Allen, Christine

    2004-01-01

    To establish a method for predicting polymer-drug compatibility as a means to guide formulation development, we carried out physicochemical analyses of polymer-drug pairs and compared the difference in total and partial solubility parameters of polymer and drug. For these studies, we employed a range of biodegradable polymers and the anticancer agent Ellipticine as the model drug. The partial and total solubility parameters for the polymer and drug were calculated using the group contribution method. Drug-polymer pairs with different enthalpy of mixing values were analyzed by physicochemical techniques including X-ray diffraction and Fourier transform infrared. Polymers identified to be compatible [i.e., polycaprolactone (PCL) and poly-beta-benzyl-L-aspartate (PBLA)] and incompatible [i.e., poly (d,l-lactide (PLA)], by the above mentioned methods, were used to formulate Ellipticine. Specifically, Ellipticine was loaded into PBLA, PCL, and PLA films using a solvent casting method to produce a local drug formulation; while, polyethylene oxide (PEO)-b-polycaprolactone (PCL) and PEO-b-poly (d,l-lactide) (PLA) copolymer micelles were prepared by both dialysis and dry down methods resulting in a formulation for systemic administration. The drug release profiles for all formulations and the drug loading efficiency for the micelle formulations were also measured. In this way, we compared formulation characteristics with predictions from physicochemical analyses and comparison of total and partial solubility parameters. Overall, a good correlation was obtained between drug formulation characteristics and findings from our polymer-drug compatibility studies. Further optimization of the PEO-b-PCL micelle formulation for Ellipticine was also performed.

  13. Mutual diffusion coefficient models for polymer-solvent systems based on the Chapman-Enskog theory

    Directory of Open Access Journals (Sweden)

    R. A. Reis

    2004-12-01

    Full Text Available There are numerous examples of the importance of small molecule migration in polymeric materials, such as in drying polymeric packing, controlled drug delivery, formation of films, and membrane separation, etc. The Chapman-Enskog kinetic theory of hard-sphere fluids with the Weeks-Chandler-Andersen effective hard-sphere diameter (Enskog-WCA has been the most fruitful in diffusion studies of simple fluids and mixtures. In this work, the ability of the Enskog-WCA model to describe the temperature and concentration dependence of the mutual diffusion coefficient, D, for a polystyrene-toluene system was evaluated. Using experimental diffusion data, two polymer model approaches and three mixing rules for the effective hard-sphere diameter were tested. Some procedures tested resulted in models that are capable of correlating the experimental data with the refereed system well for a solvent mass fraction greater than 0.3.

  14. Development of a multilayered association polymer system for sequential drug delivery

    Science.gov (United States)

    Chinnakavanam Sundararaj, Sharath kumar

    As all the physiological processes in our body are controlled by multiple biomolecules, comprehensive treatment of certain disease conditions may be more effectively achieved by administration of more than one type of drug. Thus, the primary objective of this research was to develop a multilayered, polymer-based system for sequential delivery of multiple drugs. This particular device was designed aimed at the treatment of periodontitis, a highly prevalent oral inflammatory disease that affects 90% of the world population. This condition is caused by bacterial biofilm on the teeth, resulting in a chronic inflammatory response that leads to loss of alveolar bone and, ultimately, the tooth. Current treatment methods for periodontitis address specific parts of the disease, with no individual treatment serving as a complete therapy. The polymers used for the fabrication of this multilayered device consists of cellulose acetate phthalate (CAP) complexed with Pluronic F-127 (P). After evaluating morphology of the resulting CAPP system, in vitro release of small molecule drugs and a model protein was studied from both single and multilayered devices. Drug release from single-layered CAPP films followed zero-order kinetics related to surface erosion property of the association polymer. Release studies from multilayered CAPP devices showed the possibility of achieving intermittent release of one type of drug as well as sequential release of more than one type of drug. Mathematical modeling accurately predicted the release profiles for both single layer and multilayered devices. After the initial characterization of the CAPP system, the device was specifically modified to achieve sequential release of drugs aimed at the treatment of periodontitis. The four types of drugs used were metronidazole, ketoprofen, doxycycline, and simvastatin to eliminate infection, inhibit inflammation, prevent tissue destruction, and aid bone regeneration, respectively. To obtain different erosion

  15. Development of polymer MEMS process technology as an approach to a sustainable production system

    Science.gov (United States)

    Sugiyama, Susumu; Amaya, Satoshi; Viet Dao, Dzung

    2012-03-01

    Polymethyl methacrylate (PMMA) has been proposed as a material for micro-electromechanical systems (MEMS) to initiate the research on environmentally friendly micro-nano machining technology using polymer materials. A polymer MEMS process has been developed using hot embossing and precision machining. MEMS structures less than 2 μm were successfully embossed. The PMMA layer that remained after hot embossing was removed by a polishing process to release the movable parts. A PMMA electrostatic comb-drive microactuator was fabricated. Both finger width and gap between fingers were 5 μm, and thickness was larger than 70 μm. An operated displacement of 11 μm at a drive voltage of 100 V was obtained. It was 20 times larger than that of an identical silicon device. A torsional micro mirror device driving with vertical comb actuator was fabricated. The size of the mirror was 1×1 mm2. The maximum tilt angle of 5.6 was obtained with driving voltage of 100 V and frequency up to 100 Hz. A chevron-shaped PMMA thermal actuator with a thickness of about 50 μm has been fabricated and tested successfully. The displacement was about 5 times larger than that of a Si counterpart at the same power consumption.

  16. Visualizing the Peripheral Primo Vascular System in Mice Skin by Using the Polymer Mercox

    Directory of Open Access Journals (Sweden)

    Miroslav Stefanov

    2015-09-01

    Full Text Available Objectives: As the peripheral part of the primo vascular system (PVS is difficult to visualize, we used a vascular casting material Mercox injected directly into the skin to take advantage of a simple procedure to visualize PVS structures as primo vessels (PVs and primo nodes (PNs in the skin. Methods: Two colors of the polymer Mercox were injected into mouse skin. After a partial maceration of the whole body with potassium hydroperoxide solution, we anatomized it under a stereomicroscope to trace the Mercox that had been injected into the PVS. Results: Injection of Mercox directly into the skin allowed the PVs and the PNs to be visualized. This approach can fill the PVS when the material is ejected out of the PVs or PNs. The shapes, sizes, and topographic positions of the nodes and the vessels are the hallmarks used to identify the PVS in skin when Mercox is used as a tracer. Conclusion: The direct injection of the casting material Mercox into skin, with modified partial maceration procedures, is a promising method for visualizing the PVs and the PNs in the peripheral part of the PVS in skin. The polymer Mercox can penetrate through the primo pores of the primo vascular wall and fill the PVs and the PNs. The data prove that PVs and PNs exist on the hypodermal layer of the skin.

  17. Design and test status for life support applications of SPE oxygen generation systems. [Solid Polymer Electrolyte

    Science.gov (United States)

    Titterington, W. A.; Erickson, A. C.

    1975-01-01

    An advanced six-man rated oxygen generation system has been fabricated and tested as part of a NASA/JSC technology development program for a long lived, manned spacecraft life support system. Details of the design and tests results are presented. The system is based on the Solid Polymer Electrolyte (SPE) water electrolysis technology and its nominal operating conditions are 2760 kN/sq m (400 psia) and 355 K (180 F) with an electrolysis module current density capability up to 350 mA/sq cm (326 ASF). The system is centered on a 13-cell SPE water electrolysis module having a single cell active area of 214 sq cm (33 sq in) and it incorporates instrumentation and controls for single pushbutton automatic startup/shutdown, component fault detection and isolation, and self-contained sensors and controls for automatic safe emergency shutdown. The system has been tested in both the orbital cyclic and continuous mode of operation. Various parametric tests have been completed to define the system capability for potential application in spacecraft environmental systems.

  18. Polymer films

    Science.gov (United States)

    Granick, Steve; Sukhishvili, Svetlana A.

    2004-05-25

    A film contains a first polymer having a plurality of hydrogen bond donating moieties, and a second polymer having a plurality of hydrogen bond accepting moieties. The second polymer is hydrogen bonded to the first polymer.

  19. Polymer films

    Science.gov (United States)

    Granick, Steve; Sukhishvili, Svetlana A.

    2008-12-30

    A film contains a first polymer having a plurality of hydrogen bond donating moieties, and a second polymer having a plurality of hydrogen bond accepting moieties. The second polymer is hydrogen bonded to the first polymer.

  20. Open Source Laser Polymer Welding System: Design and Characterization of Linear Low-Density Polyethylene Multilayer Welds

    Directory of Open Access Journals (Sweden)

    John J. Laureto

    2016-07-01

    Full Text Available The use of lasers to weld polymer sheets provides a means of highly-adaptive and custom additive manufacturing for a wide array of industrial, medical, and end user/consumer applications. This paper provides an open source design for a laser polymer welding system, which can be fabricated with low-cost fused filament fabrication and off-the-shelf mechanical and electrical parts. The system is controlled with free and open source software and firmware. The operation of the machine is validated and the performance of the system is quantified for the mechanical properties (peak load and weld width of linear low density polyethylene (LLDPE lap welds manufactured with the system as a function of linear energy density. The results provide incident laser power and machine parameters that enable both dual (two layers and multilayer (three layers while welding only two sheets polymer welded systems. The application of these parameter sets provides users of the open source laser polymer welder with the fundamental requirements to produce mechanically stable LLDPE multi-layer welded products, such as heat exchangers.

  1. Self-monitoring fiber reinforced polymer strengthening system for civil engineering infrastructures

    Science.gov (United States)

    Jiang, Guoliang; Dawood, Mina; Peters, Kara; Rizkalla, Sami

    2008-03-01

    Fiber reinforced polymer (FRP) materials are currently used for strengthening civil engineering infrastructures. The strengthening system is dependant on the bond characteristics of the FRP to the external surface of the structure to be effective in resisting the applied loads. This paper presents an innovative self-monitoring FRP strengthening system. The system consists of two components which can be embedded in FRP materials to monitor the global and local behavior of the strengthened structure respectively. The first component of the system is designed to evaluate the applied load acting on a structure based on elongation of the FRP layer along the entire span of the structure. Success of the global system has been demonstrated using a full-scale prestressed concrete bridge girder which was loaded up to failure. The test results indicate that this type of sensor can be used to accurately determine the load prior to failure within 15 percent of the measured value. The second sensor component consists of fiber Bragg grating sensors. The sensors were used to monitor the behavior of steel double-lap shear splices tested under tensile loading up to failure. The measurements were used to identify abnormal structural behavior such as epoxy cracking and FRP debonding. Test results were also compared to numerical values obtained from a three dimensional shear-lag model which was developed to predict the sensor response.

  2. Advanced polymer PV system: PVMaT 4A1 annual report, September 1995--September 1996

    Energy Technology Data Exchange (ETDEWEB)

    Hanoka, J; Chleboski, R; Farber, M; Fava, J; Kane, P; Martz, J [Evergreen Solar, Inc., Waltham, MA (United States)

    1997-06-01

    Purpose of this subcontract was to produce lower module and systems costs through the innovative use of polymeric materials. The Innovative Mounting System (IMS) was developed and testing begun during the first year of this contract. IMS reduces the cost of installed PV systems by reducing labor and materials costs both in the factory and in field installation. It incorporates several advances in polymers, processing methods and product design. An advanced backskin material permits elimination of the conventional Al perimeter frame by protecting and sealing the edge and by direct bonding of multifunctional mounting bars. Electrical interconnection is easier and more reliable with a new junction box. Feasibility of a non-vacuum, high-throughput lamination method was also demonstrated, involving a novel transparent encapsulant with UV stabilization package that can be laminated in air and which should lead to longer field life than conventional designs. The first-year program culminated in the fielding of prototype products with the new encapsulant, backskin, junction box, frameless edge seal, and IMS. Feedback and marketing information from potential customers were solicited. Result promises a $0.50/watt manufacturing and system cost reductions as well as increased system lifetime. The second year will complete refinement and test of the encapsulant and backskin, complete the new lamination method, and refine product designs.

  3. A New, Scalable and Low Cost Multi-Channel Monitoring System for Polymer Electrolyte Fuel Cells.

    Science.gov (United States)

    Calderón, Antonio José; González, Isaías; Calderón, Manuel; Segura, Francisca; Andújar, José Manuel

    2016-03-09

    In this work a new, scalable and low cost multi-channel monitoring system for Polymer Electrolyte Fuel Cells (PEFCs) has been designed, constructed and experimentally validated. This developed monitoring system performs non-intrusive voltage measurement of each individual cell of a PEFC stack and it is scalable, in the sense that it is capable to carry out measurements in stacks from 1 to 120 cells (from watts to kilowatts). The developed system comprises two main subsystems: hardware devoted to data acquisition (DAQ) and software devoted to real-time monitoring. The DAQ subsystem is based on the low-cost open-source platform Arduino and the real-time monitoring subsystem has been developed using the high-level graphical language NI LabVIEW. Such integration can be considered a novelty in scientific literature for PEFC monitoring systems. An original amplifying and multiplexing board has been designed to increase the Arduino input port availability. Data storage and real-time monitoring have been performed with an easy-to-use interface. Graphical and numerical visualization allows a continuous tracking of cell voltage. Scalability, flexibility, easy-to-use, versatility and low cost are the main features of the proposed approach. The system is described and experimental results are presented. These results demonstrate its suitability to monitor the voltage in a PEFC at cell level.

  4. 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...

  5. Quasi-homogenous approximation for description of the properties of dispersed systems. The basic approaches to model hardening processes in nanodispersed silica systems. Part 1. Statical polymer method

    Directory of Open Access Journals (Sweden)

    KUDRYAVTSEV Pavel Gennadievich

    2015-02-01

    Full Text Available The paper deals with possibilities to use quasi-homogenous approximation for discription of properties of dispersed systems. The authors applied statistical polymer method based on consideration of average structures of all possible macromolecules of the same weight. The equiations which allow evaluating many additive parameters of macromolecules and the systems with them were deduced. Statistical polymer method makes it possible to model branched, cross-linked macromolecules and the systems with them which are in equilibrium or non-equilibrium state. Fractal analysis of statistical polymer allows modeling different types of random fractal and other objects examined with the mehods of fractal theory. The method of fractal polymer can be also applied not only to polymers but also to composites, gels, associates in polar liquids and other packaged systems. There is also a description of the states of colloid solutions of silica oxide from the point of view of statistical physics. This approach is based on the idea that colloid solution of silica dioxide – sol of silica dioxide – consists of enormous number of interacting particles which are always in move. The paper is devoted to the research of ideal system of colliding but not interacting particles of sol. The analysis of behavior of silica sol was performed according to distribution Maxwell-Boltzmann and free path length was calculated. Using this data the number of the particles which can overcome the potential barrier in collision was calculated. To model kinetics of sol-gel transition different approaches were studied.

  6. Fiber-optic liquid level monitoring system using microstructured polymer fiber Bragg grating array sensors: performance analysis

    DEFF Research Database (Denmark)

    Marques, C. A. F.; Pospori, A.; Saez-Rodriguez, D.

    2015-01-01

    A highly sensitive liquid level monitoring system based on microstructured polymer optical fiber Bragg grating (mPOFBG) array sensors is reported for the first time. The configuration is based on five mPOFBGs inscribed in the same fiber in the 850 nm spectral region, showing the potential to inte...

  7. Polymer-grafted superparamagnetic iron oxide nanoparticles as a potential stable system for magnetic resonance imaging and doxorubicin delivery

    NARCIS (Netherlands)

    Asadi, H.; Khoee, S.; Deckers, R.

    2016-01-01

    Currently, there is high interest in developing multifunctional theranostic platforms with both imaging and therapeutic functions. Herein, we report a facile approach to develop polymer-grafted superparamagnetic iron oxide nanoparticles (SPIONs) as a promising system for imaging and drug delivery. A

  8. Development of a solid polymer electrolyte electrolysis cell module and ancillary components for a breadboard water electrolysis system

    Science.gov (United States)

    Porter, F. J., Jr.

    1972-01-01

    Solid polymer electrolyte technology in a water electrolysis system along with ancillary components to generate oxygen and hydrogen for a manned space station application are considered. Standard commercial components are utilized wherever possible. Presented are the results of investigations, surveys, tests, conclusions and recommendations for future development efforts.

  9. Theoretical and experimental research on the self-assembled system of molecularly imprinted polymers formed by salbutamol and methacrylic acid.

    Science.gov (United States)

    Jun-Bo, Liu; Yang, Shi; Shan-Shan, Tang; Rui-Fa, Jin

    2015-03-01

    The quantum chemical method was applied for screening functional monomers in the rational design of salbutamol-imprinted polymers. Salbutamol was the template molecule, and methacrylic acid was the single functional monomer. The LC-WPBE/6-31G(d,p) method was used to investigate the geometry optimization, active sites, natural bond orbital charges, binding energies of the imprinted molecule, and solvation energy. The mechanism of action between salbutamol and methacrylic acid was also discussed. The theoretical results show that salbutamol interacts with functional monomers by hydrogen bonds, and the salbutamol-imprinted polymers with a ratio of 1:4 (salbutamol/methacrylic acid) in acetonitrile had the highest stability. The salbutamol-imprinted polymers were prepared by precipitation polymerization. The experimental results indicated that the maximum adsorption capacity for salbutamol toward molecularly imprinted polymers was 7.33 mg/g, and the molecularly imprinted polymers had a higher selectivity for salbutamol than for norepinephrine and terbutaline sulfate. Herein, the studies can provide theoretical and experimental references for the salbutamol molecular imprinted system.

  10. A multi-objective optimisation model for a general polymer electrolyte membrane fuel cell system

    Science.gov (United States)

    Ang, Sheila Mae C.; Brett, Daniel J. L.; Fraga, Eric S.

    This paper presents an optimisation model for a general polymer electrolyte membrane (PEM) fuel cell system suitable for efficiency and size trade-offs investigation. Simulation of the model for a base case shows that for a given output power, a more efficient system is bigger and vice versa. Using the weighting method to perform a multi-objective optimisation, the Pareto sets were generated for different stack output powers. A Pareto set, presented as a plot of the optimal efficiency and area of the membrane electrode assembly (MEA), gives a quantitative description of the compromise between efficiency and size. Overall, our results indicate that, to make the most of the size-efficiency trade-off behaviour, the system must be operated at an efficiency of at least 40% but not more than 47%. Furthermore, the MEA area should be at least 3 cm 2 W -1 for the efficiency to be practically useful. Subject to the constraints imposed on the model, which are based on technical practicalities, a PEM fuel cell system such as the one presented in this work cannot operate at an efficiency above 54%. The results of this work, specifically the multi-objective model, will form a useful and practical basis for subsequent techno-economic studies for specific applications.

  11. Low Leachable Container System Consisting of a Polymer-Based Syringe with Chlorinated Isoprene Isobutene Rubber Plunger Stopper.

    Science.gov (United States)

    Kiminami, Hideaki; Takeuchi, Katsuyuki; Nakamura, Koji; Abe, Yoshihiko; Lauwers, Philippe; Dierick, William; Yoshino, Keisuke; Suzuki, Shigeru

    2015-01-01

    A 36 month leachable study on water for injection in direct contact within a polymer-based prefillable syringe consisting of a cyclo olefin polymer barrel, a chlorinated isoprene isobutene rubber plunger stopper, a polymer label attached on the barrel, and a secondary packaging was conducted at 25 ± 2 °C and 60 ± 5% relative humidity. Through the various comparison studies, no difference in the leachable amounts was observed between this polymer-based prefilled syringe and a glass bottle as a blank sample reference by 36 months. No influence on the leachables study outcome was noted from the printed label and/or label adhesive or from the secondary packaging. In an additional study, no acrylic acid used as the label adhesive leachable was detected by an extended storage for 45 months at 25 ± 2 °C and 60 ± 5% relative humidity as a worst case. To obtain more details, a comparison extractable study was conducted between a cyclo olefin polymer barrel and a glass barrel. In addition, chlorinated isoprene isobutene rubber and bromo isoprene isobutene rubber were compared. As a result, no remarkable difference was found in the organic extractables for syringe barrels. On the other hand, in the case of element extractable analysis, the values for the cyclo olefin polymer barrel were lower than that for the glass barrel. For the plunger stoppers, the chlorinated isoprene isobutene rubber applied in this study was showing a lower extractable profile as compared to the bromo isoprene isobutene rubber, both for organic and element extractables. In conclusion, the proposed polymer-based prefillable syringe system has great potential and represents a novel alternative that can achieve very low level extractable profiles and can bring additional value to the highly sensitive biotech drug market. A 36 month leachable study on water for injection in direct contact within a cyclo olefin polymer barrel and chlorinated isoprene isobutene rubber plunger stopper that has a

  12. Dielectric spectroscopy investigation of ion-containing and intermolecular hydrogen-bonded polymer systems

    Science.gov (United States)

    Atorngitjawat, Pornpen

    Ion-containing and intermolecular hydrogen-bonded polymers are used widely in a variety of industrial and commercial applications, from food packaging to battery electrolytes to pharmaceuticals. Yet the dynamics of these polymers, which are both complex and important to the application, are poorly understood. This thesis provides the first systematic study of the dynamics of several ion-containing and intermolecular hydrogen-bonded polymers by broadband dielectric relaxation spectroscopy. The systems under consideration include sulfonated polystyrene (SPS) in acid (SPS-H) and neutralized forms, and mixtures of poly(2-vinylpyridine) (P2VPy) with lithium perchlorate (LiClO4) and low molecular weight phenolic molecules. Dynamic mechanical analysis, Fourier transform infrared spectroscopy, differential scanning calorimetry, small-angle X-ray scattering and wide-angle X-ray diffraction were employed in a complementary role. Multiple relaxations were generally observed at high temperatures. For SPS ionomers, the segmental process, Maxwell-Wagner-Sillars interfacial polarization, and electrode polarization were detected. Three relaxations were also found in spectra of SPS-H, attributed to the segmental process, hydrogen bond association/dissociation, and electrode polarization. Three dielectric relaxations above the segmental process were observed for P2VPy-LiClO4 mixtures: ion-mode relaxation, slow hindered segmental relaxation and electrode polarization. However, only electrode polarization was observed above the segmental relaxation for all P2VPy--small phenolic molecule mixtures, except P2VPy + 10 mol% 2,3,3,4,4,5-hexahydroxybenzophenone. This mixture exhibited an additional relaxation due to Maxwell-Wagner-Sillars interfacial polarization, arising from the existence of phase-separated complexes within the P2VPy matrix. Sub-Tg local relaxations were suppressed by ionic intermolecular interactions for SPS ionomers and P2VPy-LiClO4 mixtures. Intermolecular hydrogen

  13. Control and experimental characterization of a methanol reformer for a 350 W high temperature polymer electrolyte membrane fuel cell system

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen; Sahlin, Simon Lennart

    2013-01-01

    This work presents a control strategy for controlling the methanol reformer temperature of a 350 W high temperature polymer electrolyte membrane fuel cell system, by using a cascade control structure for reliable system operation. The primary states affecting the methanol catalyst bed temperature...... is the water and methanol mixture fuel flow and the burner fuel/air ratio and combined flow. An experimental setup is presented capable of testing the methanol reformer used in the Serenergy H3 350 Mobile Battery Charger; a high temperature polymer electrolyte membrane (HTPEM) fuel cell system....... The experimental system consists of a fuel evaporator utilizing the high temperature waste gas from the cathode air cooled 45 cell HTPEM fuel cell stack. The fuel cells used are BASF P1000 MEAs which use phosphoric acid doped polybenzimidazole membranes. The resulting reformate gas output of the reformer system...

  14. Linseed oil gelled emulsion: A successful fat replacer in dry fermented sausages.

    Science.gov (United States)

    Alejandre, Marta; Poyato, Candelaria; Ansorena, Diana; Astiasarán, Iciar

    2016-11-01

    Different levels of animal fat replacement by a high omega-3 content carrageenan gelled emulsion in dry fermented sausages were studied in order to improve their fatty acid composition. Percentages of fat replacement were 26.3% (SUB1), 32.8% (SUB2) and 39.5% (SUB3). α-linolenic acid (ALA) content increased up to 1.81, 2.19 and 2.39g/100g (SUB1, SUB2, and SUB3 products) as compared to the Control (0.35g/100g), implying an increment in polyunsaturated fatty acids (PUFA) supply (up to 10.3%) and reductions in omega-6/ omega-3 ratio (75, 82 and 84%, respectively). Peroxides and TBARs values were not affected (P>0.05) by the fat modification and a slight low formation of volatile aldehydes derived from lipid oxidation was detected. Fat replacement did not cause relevant modifications on the instrumental color properties and no sensory differences (P>0.05) were found between Control and SUB2 products (32.8%) for taste and juiciness, pointing out the viability of this formulation for human consumption.

  15. Gelling process for sodium alginate: New technical approach by using calcium rich micro-spheres.

    Science.gov (United States)

    Vicini, Silvia; Castellano, Maila; Mauri, Marco; Marsano, Enrico

    2015-12-10

    Alginate based materials have become an important class of products in many fields from the pharmaceutical industry to tissue engineering, because of their ability to create stimuli responsive hydrogels. We present a new technical approach for obtaining a controlled gelling process, based on the quantities of Ca(2+) rich alginate micro-beads added as crosslinkers. The gels have been evaluated in light of the amount of Ca(2+) added to the alginate solution, and in light of the different dimensions of the micro-beads, using rheological measurements to assess the variation in the storage modulus (G'), loss modulus (G'') and complex viscosity (η(*)) as well as swelling and deswelling tests. The methodology was developed to obtain a material with specific characteristics for application in the field of conservation. The material had to be able to create a stable gel after being applied on the artwork surface and to confine the solvent action at the interface during cleaning operations. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Extraction and Characterization of Highly Gelling Low Methoxy Pectin from Cashew Apple Pomace

    Directory of Open Access Journals (Sweden)

    Beda M. Yapo

    2013-12-01

    Full Text Available Investigation on the pectic substances of cashew (Anacardium occidentale L. apple under different acid-extraction conditions (pH 1.0, 1.5, and 2.0 showed that more than 10%–25% of A. occidentale pectins (AOP could be extracted, depending on the extractant strength. The extracted AOP contained high amounts of galacturonic acid (GalA: 69.9%–84.5% with some neutral sugars of which rhamnose (Rha: 1.3%–2.5%, arabinose (Ara: 2.6%–5.4%, and galactose (Gal: 4.7%–8.6% were the main constituents. The degree of methoxylation (DM was in the range of 28%–46% and was only slightly affected by the extractant strength, thereby indicating isolation of naturally low methoxy pectins (LMP. In terms of gelling capability, AOP yielded firmer Ca2+-mediated LMP gels than commercial citrus LMP with comparable DM. Cashew apple pomace, therefore, appears to be a potentially viable source for possible production of “non-chemically or enzymatically-tailored” LMP.

  17. Art-matrix theory and cognitive distance: Farago, Preziosi, and Gell on art and enchantment

    Directory of Open Access Journals (Sweden)

    Jakub Stejskal

    2015-12-01

    Full Text Available Theories that treat art objects primarily as agents embedded in a causal nexus of agent–patient relationships, as opposed to studying them as expressions or symbols encoding meanings, tend to identify art’s agency with its power to enchant recipients. I focus on two such approaches, the art-matrix theory of Claire Farago and Donald Preziosi and the art-nexus theory of Alfred Gell. Their authors stress the potential of art to make its enchanting power the topic of our experience with it, that is, to disenchant its own enchantment. This raises the following question: If artworks are to be understood as agents enchanting their recipients, how can they become forces of disenchantment? I argue that the shift in perspective from perceiving art objects as indices of agency within a matrix/nexus to approaching them as possible means of gaining cognitive distance is inadequately addressed by both theories; this is due to features inherent to their respective theoretical outlooks.

  18. Successful disinfection protocol for orchid seeds and influence of gelling agent on germination and growth

    Directory of Open Access Journals (Sweden)

    Tomaž JEVŠNIK

    2015-11-01

    Full Text Available Artificial propagation of endangered orchid species is one of the most important actions of conservationists often jeopardized by low numbers of acquired seed, its contamination and viability. Disinfection and chemical composition of media are two of the most important factors contributing to better germination in temperate orchid species. The article deals with three world genera (Epidendrum nocturnum, Prosthechea garciana, Maxillaria rufescens and one commercial hybrid (Zygopetalum and describes an effective method of orchid seed disinfection carried out in a centrifuge. Germination percentages of all three genera and one hybrid were between 60 and 90 % from which we concluded that the risk of physical damage to the seeds by centrifugation is not significant. The time needed for disinfected seeds (E. nocturnum, P. garciana, M. rufescens to swell-form protocorms was 10 days shorter compared to undisinfected seeds (Zygopetalum hybrid - green capsule method and some other studies. Adequate wetting and stratification of the seed is very important for successful germination, which resembles processes in natural environment. Additionally, this method solves the problems of collecting and transferring the seeds after disinfection. It is also important that the time needed for disinfection is shorter, which is desirable for some sensitive species. Our study also focuses on importance of gelling agent, namely Gellan gum and agar, since we noticed an obvious superiority of the former in all phases of in vitro development.

  19. Generalized isospin, generalized mass groups, and generalized Gell-Mann--Okubo formalism

    CERN Document Server

    Beaudoin, N; Sandapen, R

    2013-01-01

    The current concepts of isospin and baryon mass groups are only well-adapted to deal with baryon multiplets involving both the u and d quarks, and some other quark k. In this paper, we generalize isospin and mass groups to accommodate baryon multiplets involving quarks of any flavor, and the Gell-Mann--Okubo (GMO) formalism is generalized accordingly. Generalized isospin proves to be a simple and valuable framework when working in non-udk baryon multiplets, and provides new quantum numbers that allows us to distinguish \\Lambda-like baryons from \\Sigma-like baryons in the non-udk multiplets. The generalized GMO formalism allows us to quantify the quality of flavor symmetries seen in baryon multiplets, and also allows us to predict the masses of all observable J^P = 1/2^+ and 3/2^+ baryons with an estimated accuracy on the order of 50 MeV in the worst cases, on mass scales that span anywhere from 1000 MeV to 15000 MeV.

  20. Generation of a Focused Poly(amino ether Library: Polymer-mediated Transgene Delivery and Gold-Nanorod based Theranostic Systems

    Directory of Open Access Journals (Sweden)

    Lucas Vu, James Ramos, Thrimoorthy Potta, Kaushal Rege

    2012-01-01

    Full Text Available A focused library of twenty-one cationic poly(amino ethers was synthesized following ring-opening polymerization of two diglycidyl ethers by different oligoamines. The polymers were screened in parallel for plasmid DNA (pDNA delivery, and transgene expression efficacies of individual polymers were compared to those of 25 kDa polyethylenimine (PEI, a current standard for polymer-mediated transgene delivery. Seven lead polymers that demonstrated higher transgene expression than PEI in pancreatic and prostate cancer cells lines were identified from the screen. All seven lead polymers showed highest transgene expression at a polymer:pDNA weight ratio of 5:1 in the MIA PaCa-2 pancreatic cancer cell line. Among the conditions studied, transgene expression efficacy correlated with minimal polymer cytotoxicity but not polyplex sizes. In addition, this study indicated that methylene spacing between amine centers in the monomers, amine content, and molecular weight of the polymers are all significant factors and should be considered when designing polymers for transgene delivery. A lead effective polymer was employed for coating gold nanorods, leading to theranostic nanoassemblies that possess combined transgene delivery and optical imaging capabilities, leading to potential theranostic systems.

  1. Potentiometric Multisensory Systems with Novel Ion-Exchange Polymer-Based Sensors for Analysis of Drugs

    Directory of Open Access Journals (Sweden)

    Olga V. Bobreshova

    2012-01-01

    Full Text Available This paper examines potentiometric multisensory systems that consist of novel cross-sensitive PD-sensors (Potential Donnan-sensors. The analytical signal of PD-sensors is the Donnan potential at the ion-exchange polymer/electrolyte test solution interface. The use of novel sensors for the quantitative analysis of multicomponent aqueous solutions of amino acids, vitamins and medical substances is based on protolytic and ion-exchange reactions at the interfaces of ion-exchangers and test solutions. The potentiometric sensor arrays consist of PD-sensors and ion-selective electrodes. Such systems were developed for the multicomponent quantitative analysis of lysine monohydrochloride, thiamine chloride and novocaine hydrochloride solutions that contained salts of alkaline and alkaline-earth metals, as well as for mixed solutions of nicotinic acid and pyridoxine hydrochloride. Multivariate methods of analysis were used for sensor calibration and the analysis of the total response of sensor arrays. The errors of measurement of the electrolytes in aqueous solutions did not exceed 10%. The developed multisensory systems were used to determine the composition of a therapeutic “Mineral salt with low content of sodium chloride” and to determine concentrations of novocaine in sewage samples from a dental clinic.

  2. Rapid prototyping of microfluidic systems using a PDMS/polymer tape composite.

    Science.gov (United States)

    Kim, Jungkyu; Surapaneni, Rajesh; Gale, Bruce K

    2009-05-01

    Rapid prototyping of microfluidic systems using a combination of double-sided tape and PDMS (polydimethylsiloxane) is introduced. PDMS is typically difficult to bond using adhesive tapes due to its hydrophobic nature and low surface energy. For this reason, PDMS is not compatible with the xurography method, which uses a knife plotter and various adhesive coated polymer tapes. To solve these problems, a PDMS/tape composite was developed and demonstrated in microfluidic applications. The PDMS/tape composite was created by spinning it to make a thin layer of PDMS over double-sided tape. Then the PDMS/tape composite was patterned to create channels using xurography, and bonded to a PDMS slab. After removing the backing paper from the tape, a complete microfluidic system could be created by placing the construct onto nearly any substrate; including glass, plastic or metal-coated glass/silicon substrates. The bond strength was shown to be sufficient for the pressures that occur in typical microfluidic channels used for chemical or biological analysis. This method was demonstrated in three applications: standard microfluidic channels and reactors, a microfluidic system with an integrated membrane, and an electrochemical biosensor. The PDMS/tape composite rapid prototyping technique provides a fast and cost effective fabrication method and can provide easy integration of microfluidic channels with sensors and other components without the need for a cleanroom facility.

  3. Biostable glucose permeable polymer

    DEFF Research Database (Denmark)

    2017-01-01

    A new biostable glucose permeable polymer has been developed which is useful, for example, in implantable glucose sensors. This biostable glucose permeable polymer has a number of advantageous characteristics and, for example, does not undergo hydrolytic cleavage and degradation, thereby providing...... a composition that facilitates long term sensor stability in vivo. The versatile characteristics of this polymer allow it to be used in a variety of contexts, for example to form the body of an implantable glucose sensor. The invention includes the polymer composition, sensor systems formed from this polymer...

  4. Wetting and dispersion in ceramic/polymer melt injection molding systems

    Energy Technology Data Exchange (ETDEWEB)

    Sacks, M.D. (Florida Univ., Gainesville, FL (United States). Dept. of Materials Science and Engineering); Williams, J.W. (Florida Univ., Gainesville, FL (United States). Dept. of Materials Science and Engineering 3M Co., St. Paul, MN (United States))

    1993-01-01

    This program had two major areas of emphasis: (1) factors influencing state of particulate dispersion and rheological properties of ceramic powder/polymer melt mixtures, and (2) effect of interfacial bonding strength on mechanical and rheological properties of ceramic particle/polymer composites. Alumina and silica in various polyethylenes were used.

  5. Wetting and dispersion in ceramic/polymer melt injection molding systems. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Sacks, M.D. [Florida Univ., Gainesville, FL (United States). Dept. of Materials Science and Engineering; Williams, J.W. [Florida Univ., Gainesville, FL (United States). Dept. of Materials Science and Engineering]|[3M Co., St. Paul, MN (United States)

    1993-05-01

    This program had two major areas of emphasis: (1) factors influencing state of particulate dispersion and rheological properties of ceramic powder/polymer melt mixtures, and (2) effect of interfacial bonding strength on mechanical and rheological properties of ceramic particle/polymer composites. Alumina and silica in various polyethylenes were used.

  6. Multi-scale optical metrology for the quality control of polymer microfluidic systems

    DEFF Research Database (Denmark)

    Tosello, Guido; Marinello, Francesco; Hansen, Hans Nørgaard

    2009-01-01

    Micro injection moulding is a replication technology enabling large scale production of polymer-based micro products. To this respect, optical measuring technologies were selected to perform the quality control of a polymer micro-component: an optical coordinate measuring machine (CMM) and a whit...

  7. Inference of Polymer Adsorption from Electrical Double Layer Measurements : the Silver Iodide-Polyvinyl Alcohol System

    NARCIS (Netherlands)

    Koopal, L.K.

    1978-01-01

    The purpose of this study was to investigate how the double layer properties of charged particles are modified by the presence of adsorbed polymer molecules and to obtain information on the conformation of the polymer layer from the observed alterations in the double layer properties.In chapter 1. t

  8. Multi-scale optical metrology for the quality control of polymer microfluidic systems

    DEFF Research Database (Denmark)

    Tosello, Guido; Marinello, Francesco; Hansen, Hans Nørgaard

    2009-01-01

    Micro injection moulding is a replication technology enabling large scale production of polymer-based micro products. To this respect, optical measuring technologies were selected to perform the quality control of a polymer micro-component: an optical coordinate measuring machine (CMM) and a whit...

  9. Variable diameter CO2 laser ring-cutting system adapted to a zoom microscope for applications on polymer tapes.

    Science.gov (United States)

    Förster, Erik; Bohnert, Patrick; Kraus, Matthias; Kilper, Roland; Müller, Ute; Buchmann, Martin; Brunner, Robert

    2016-11-20

    This paper presents the conception and implementation of a variable diameter ring-cutting system for a CO2 laser with a working wavelength of 10.6 μm. The laser-cutting system is adapted to an observation zoom microscope for combined use and is applicable for the extraction of small circular areas from polymer films, such as forensic adhesive tapes in a single shot. As an important characteristic for our application, the variable diameter ring-cutting system provides telecentricity in the target area. Ring diameters are continuously tunable between 500 μm and 2 mm. A minimum width of less than 20 μm was found for the ring profile edge. The basic characteristics of the system, including telecentricity, were experimentally evaluated and demonstrated by cutting experiments on different polymer tapes and further exemplary samples.

  10. Performance of a Polymer Flood with Shear-Thinning Fluid in Heterogeneous Layered Systems with Crossflow

    Directory of Open Access Journals (Sweden)

    Kun Sang Lee

    2011-08-01

    Full Text Available Assessment of the potential of a polymer flood for mobility control requires an accurate model on the viscosities of displacement fluids involved in the process. Because most polymers used in EOR exhibit shear-thinning behavior, the effective viscosity of a polymer solution is a highly nonlinear function of shear rate. A reservoir simulator including the model for the shear-rate dependence of viscosity was used to investigate shear-thinning effects of polymer solution on the performance of the layered reservoir in a five-spot pattern operating under polymer flood followed by waterflood. The model can be used as a quantitative tool to evaluate the comparative studies of different polymer flooding scenarios with respect to shear-rate dependence of fluids’ viscosities. Results of cumulative oil recovery and water-oil ratio are presented for parameters of shear-rate dependencies, permeability heterogeneity, and crossflow. The results of this work have proven the importance of taking non-Newtonian behavior of polymer solution into account for the successful evaluation of polymer flood processes. Horizontal and vertical permeabilities of each layer are shown to impact the predicted performance substantially. In reservoirs with a severe permeability contrast between horizontal layers, decrease in oil recovery and sudden increase in WOR are obtained by the low sweep efficiency and early water breakthrough through highly permeable layer, especially for shear-thinning fluids. An increase in the degree of crossflow resulting from sufficient vertical permeability is responsible for the enhanced sweep of the low permeability layers, which results in increased oil recovery. It was observed that a thinning fluid coefficient would increase injectivity significantly from simulations with various injection rates. A thorough understanding of polymer rheology in the reservoir and accurate numerical modeling are of fundamental importance for the exact estimation

  11. Design and evaluation of a gastroretentive drug delivery system for metformin HCl using synthetic and semi-synthetic polymers.

    Science.gov (United States)

    Meka, Venkata Srikanth; Gorajana, Adinaravyana; Dharmanlingam, Senthil Rajan; Kolapalli, Venkata Ramana Murthy

    2013-12-01

    The aim of the present research was to prepare and evaluate a gastroretentive drug delivery system for metformin HCl, using synthetic and semi-synthetic polymers. The floating approach was applied for preparing gastroretentive tablets (GRT) and these tablets were manufactured by the direct compression method. The drug delivery system comprises of synthetic and semi-synthetic polymers such as polyethylene oxide and Carboxymethyl ethyl cellulose (CMEC) as release-retarding polymers. GRT were evaluated for physico-chemical properties like weight variation, hardness, assay friability, in vitro floating behaviour, swelling studies, in vitro dissolution studies and rate order kinetics. Based upon the drug release and floating properties, two formulations (MP04 & MC03) were selected as optimized formulations. The optimized formulations MP04 and MC03 followed zero order rate kinetics, with non-Fickian diffusion and first order rate kinetics with erosion mechanism, respectively. The optimized formulation was characterised with FTIR studies and it was observed that there was no interaction between the drug and polymers.

  12. Temperature range extension of an organically crosslinked polymer system and its successful field application for water and gas shutoff

    Energy Technology Data Exchange (ETDEWEB)

    Vasquez, Julio; Eoff, Larry; Dalrymple, Dwyann [Halliburton, Rio de Janeiro. RJ (Brazil)

    2008-07-01

    Excessive water production from hydrocarbon reservoirs is one of the most serious problems in the oil industry. Water production greatly affects the economic life of producing wells and brings along secondary problems such as sand production, corrosion, and tubular scale. Remediation techniques for controlling water production, generally referred to as conformance control, include the use of polymer systems to reduce or plug permeability to water. This paper presents the laboratory evaluation of an organically crosslinked polymer (OCP) system used as a sealant for water control problems in hydrocarbon wells. Originally, the OCP system had a limited working temperature range (140 deg to 260 deg F). Recently, an alternative base polymer (for low temperatures) and a retarder (for high temperatures) have been introduced to expand the temperature range of applicability of the OCP system from 70 deg F to 350 deg F without compromising its effectiveness or thermal stability. More than 400 jobs have been performed with the OCP system around the world to address conformance problems such as water coning/cresting, high-permeability streaks, gravel pack isolation, fracture shutoff, and casing leak repairs. This paper presents an overview of case histories that used the OCP system in various regions of the world for a wide variety of applications. (author)

  13. Light-responsive polymer microcapsules as delivery systems for natural active agents

    Energy Technology Data Exchange (ETDEWEB)

    Bizzarro, Valentina; Carfagna, Cosimo; Cerruti, Pierfrancesco [Institute for Polymers, Composites and Biomaterials (IPCB-CNR), Via Campi Flegrei, 34, 80078 Pozzuoli, NA (Italy); Marturano, Valentina; Ambrogi, Veronica [Department of Chemical, Materials and Production Engineering (DICMAPI), University of Naples “Federico II”, P. le Tecchio, 80, 80125 Napoli (Italy); Institute for Polymers, Composites and Biomaterials (IPCB-CNR), Via Campi Flegrei, 34, 80078 Pozzuoli, NA (Italy)

    2016-05-18

    In this work we report the preparation and the release behavior of UV-responsive polymeric microcapsules containing essential oils as a core. The oil acted also as a monomer solvent during polymerization. Accordingly, the potentially toxic organic solvent traditionally used was replaced with a natural active substance, resulting in a more sustainable functional system. Polymer shell was based on a lightly cross-linked polyamide containing UV-sensitive azobenzene moieties in the main chain. The micro-sized capsules were obtained via interfacial polycondensation in o/w emulsion, and their mean size was measured via Dynamic Light Scattering. Shape and morphology were analyzed through Scanning Electron and Optical Microscopy. UV-responsive behavior was evaluated via spectrofluorimetry, by assessing the release kinetics of a fluorescent probe molecule upon UV light irradiation (λ{sub max}=360 nm). The irradiated samples showed an increase in fluorescence intensity, in accordance with the increase of the probe molecule concentration in the release medium. As for the un-irradiated sample, no changes could be detected demonstrating the effectiveness of the obtained releasing system.

  14. Antimicrobial polymers.

    Science.gov (United States)

    Jain, Anjali; Duvvuri, L Sailaja; Farah, Shady; Beyth, Nurit; Domb, Abraham J; Khan, Wahid

    2014-12-01

    Better health is basic requirement of human being, but the rapid growth of harmful pathogens and their serious health effects pose a significant challenge to modern science. Infections by pathogenic microorganisms are of great concern in many fields such as medical devices, drugs, hospital surfaces/furniture, dental restoration, surgery equipment, health care products, and hygienic applications (e.g., water purification systems, textiles, food packaging and storage, major or domestic appliances etc.) Antimicrobial polymers are the materials having the capability to kill/inhibit the growth of microbes on their surface or surrounding environment. Recently, they gained considerable interest for both academic research and industry and were found to be better than their small molecular counterparts in terms of enhanced efficacy, reduced toxicity, minimized environmental problems, resistance, and prolonged lifetime. Hence, efforts have focused on the development of antimicrobial polymers with all desired characters for optimum activity. In this Review, an overview of different antimicrobial polymers, their mechanism of action, factors affecting antimicrobial activity, and application in various fields are given. Recent advances and the current clinical status of these polymers are also discussed.

  15. A strategy for tuning achiral main-chain polymers into helical assemblies and chiral memory systems.

    Science.gov (United States)

    Yang, Dong; Zhao, Yin; Lv, Kai; Wang, Xiufeng; Zhang, Wei; Zhang, Li; Liu, Minghua

    2016-01-28

    A general strategy to tune the achiral main chain polymers into helical nanoassemblies was proposed based on the co-gelation approach. As an example, two achiral main chain polymers, PCz8 and PSi8, were selected, and their co-assembly with an amphiphilic l- or d-glutamide gelator was investigated. Although the polymers could not form gels individually, they could form co-gels with the gelator and the resultant gels exhibited macroscopic supramolecular chirality, which could be confirmed by CD spectra and SEM observations. Moreover, the supramolecular chirality can be memorized even after the gelator molecules were removed. Remarkably, either the gelator-containing or gelator-free chiral polymer assemblies showed circularly polarized luminescence (CPL), which is usually inherent to intrinsic chiral polymers. It was suggested that during the co-gelation, the chirality of the gelator was transferred to and memorized by the achiral polymers. The approach seems to be general and we provided the first example to tune the achiral polymers into helical assemblies through the co-gelation.

  16. Drug carrier systems based on water-soluble cationic beta-cyclodextrin polymers.

    Science.gov (United States)

    Li, Jianshu; Xiao, Huining; Li, Jiehua; Zhong, YinPing

    2004-07-08

    This study was designed to synthesize, characterize and investigate the drug inclusion property of a series of novel cationic beta-cyclodextrin polymers (CPbetaCDs). Proposed water-soluble polymers were synthesized from beta-cyclodextrin (beta-CD), epichlorohydrin (EP) and choline chloride (CC) through a one-step polymerization procedure by varying molar ratio of EP and CC to beta-CD. Physicochemical properties of the polymers were characterized with colloidal titration, nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC) and aqueous solubility determination. The formation of naproxen/CPbetaCDs inclusion complexes was confirmed by NMR and fourier transform infrared spectroscopy (FT-IR). Cationic beta-CD polymers showed better hemolytic activities than parent beta-CD and neutral beta-CD polymer in hemolysis test. The morphological study of erythrocytes revealed a cell membrane invagination induced by the cationic groups. The effects of molecular weight and charge density of the polymers on their inclusion and release performance of naproxen were also investigated through phase-solubility and dissolution studies. It was found that the cationic beta-CD polymers with high molecular weight or low charge density exhibited better drug inclusion and dissolution abilities.

  17. Towards a portable microchip system with integrated thermal control and polymer waveguides for real-time PCR

    DEFF Research Database (Denmark)

    Wang, Zhenyu; Sekulovic, Andrea; Kutter, Jörg Peter

    2006-01-01

    performed with a dilution series of C. jejuni DNA template (2 to 200 pg/mu l) could be quantitatively detected and compared with a conventional post-PCR analysis (DNA gel electrophoresis). The presented approach provided reliable real-time quantitative information of the PCR amplification of the targeted......A novel real-time PCR microchip platform with integrated thermal system and polymer waveguides has been developed. The integrated polymer optical system for real-time monitoring of PCR was fabricated in the same SU-8 layer as the PCR chamber, without additional masking steps. Two suitable DNA...... binding dyes, SYTOX Orange and TO-PRO-3, were selected and tested for the real-time PCR processes. As a model, cadF gene of Campylobacter jejuni has been amplified on the microchip. Using the integrated optical system of the real-time PCR microchip, the measured cycle threshold values of the real-time PCR...

  18. 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.

  19. Rheological profiling of organogels prepared at critical gelling concentrations of natural waxes in a triacylglycerol solvent.

    Science.gov (United States)

    Patel, Ashok R; Babaahmadi, Mehrnoosh; Lesaffer, Ans; Dewettinck, Koen

    2015-05-20

    The aim of this study was to use a detailed rheological characterization to gain new insights into the gelation behavior of natural waxes. To make a comprehensive case, six natural waxes (differing in the relative proportion of chemical components: hydrocarbons, fatty alcohols, fatty acids, and wax esters) were selected as organogelators to gel high-oleic sunflower oil. Flow and dynamic rheological properties of organogels prepared at critical gelling concentrations (Cg) of waxes were studied and compared using drag (stress ramp and steady flow) and oscillatory shear (stress and frequency sweeps) tests. Although, none of the organogels satisfied the rheological definition of a "strong gel" (G″/G' (ω) ≤ 0.1), on comparing the samples, the strongest gel (highest critical stress and dynamic, apparent, and static yield stresses) was obtained not with wax containing the highest proportion of wax esters alone (sunflower wax, SFW) but with wax containing wax esters along with a higher proportion of fatty alcohols (carnauba wax, CRW) although at a comparatively higher Cg (4%wt for latter compared to 0.5%wt for former). As expected, gel formation by waxes containing a high proportion of lower melting fatty acids (berry, BW, and fruit wax, FW) required a comparatively higher Cg (6 and 7%wt, respectively), and in addition, these gels showed the lowest values for plateau elastic modulus (G'LVR) and a prominent crossover point at higher frequency. The gelation temperatures (TG'=G″) for all the studied gels were lower than room temperature, except for SFW and CRW. The yielding-type behavior of gels was evident, with most gels showing strong shear sensitivity and a weak thixotropic recovery. The rheological behavior was combined with the results of thermal analysis and microstructure studies (optical, polarized, and cryo-scanning electron microscopy) to explain the gelation properties of these waxes.

  20. Design of a multi-dopamine-modified polymer ligand optimally suited for interfacing magnetic nanoparticles with biological systems.

    Science.gov (United States)

    Wang, Wentao; Ji, Xin; Na, Hyon Bin; Safi, Malak; Smith, Alexandra; Palui, Goutam; Perez, J Manuel; Mattoussi, Hedi

    2014-06-03

    We have designed a set of multifunctional and multicoordinating polymer ligands that are optimally suited for surface functionalizing iron oxide and potentially other magnetic nanoparticles (NPs) and promoting their integration into biological systems. The amphiphilic polymers are prepared by coupling (via nucleophilic addition) several amine-terminated dopamine anchoring groups, poly(ethylene glycol) moieties, and reactive groups onto a poly(isobutylene-alt-maleic anhydride) (PIMA) chain. This design greatly benefits from the highly efficient and reagent-free one-step reaction of maleic anhydride groups with amine-containing molecules. The availability of several dopamine groups in the same ligand greatly enhances the ligand affinity, via multiple coordination, to the magnetic NPs, while the hydrophilic and reactive groups promote colloidal stability in buffer media and allow subsequent conjugation with target biomolecules. Iron oxide nanoparticles ligand exchanged with these polymer ligands have a compact hydrodynamic size and exhibit enhanced long-term colloidal stability over the pH range of 4-12 and in the presence of excess electrolytes. Nanoparticles ligated with terminally reactive polymers have been easily coupled to target dyes and tested in live cell imaging with no measurable cytotoxicity. Finally, the resulting hydrophilic nanoparticles exhibit large and size-dependent r2 relaxivity values.

  1. Development and evaluation of gastroretentive raft forming systems incorporating curcumin-Eudragit® EPO solid dispersions for gastric ulcer treatment.

    Science.gov (United States)

    Kerdsakundee, Nattha; Mahattanadul, Sirima; Wiwattanapatapee, Ruedeekorn

    2015-08-01

    Novel raft forming systems incorporating curcumin-Eudragit® EPO solid dispersions were developed to prolong the gastric residence time and provide for a controlled release therapy of curcumin to treat gastric ulcers. The solid dispersions of curcumin with Eudragit® EPO were prepared by the solvent evaporation method at various ratios to improve the solubility and the dissolution of curcumin. The optimum weight ratio of 1:5 for curcumin to Eudragit® EPO was used to incorporate into the raft forming systems. The raft forming formulations were composed of curcumin-Eudragit® EPO solid dispersions, sodium alginate as a gelling polymer and calcium carbonate for generating divalent Ca(2+) ions and carbon dioxide to form a floating raft. All formulations formed a gelled raft in 1min and sustained buoyancy on the 0.1N hydrochloric acid (pH 1.2) surface with a 60-85% release of curcumin within 8h. The curative effect on the acetic acid-induced chronic gastric ulcer in rats was determined. The curcumin raft forming formulations at 40mg/kg once daily showed a superior curative effect on the gastric ulcer in terms of the ulcer index and healing index than the standard antisecretory agent: lansoprazole (1mg/kg, twice daily) and a curcumin suspension (40mg/kg, twice daily). These studies demonstrated that the new raft forming systems containing curcumin solid dispersions are promising carriers for a stomach-specific delivery of poorly soluble lipophilic compounds.

  2. STUDY ON CO-CURING REACTION IN CHAIN PROLONGED BISMALEIMIDE-UNSATURATED POLYMER RESIN SYSTEM

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The curing process of chemical reacton between flexible unsaturated polymer resin and diphenylmethane bismaleimides which have been chain-prolonged by diaminodiphenylmethane is presented, also the kinetics parameters and curing technology are investigated.

  3. Polymer Derived Rare Earth Silicate Nanocomposite Protective Coatings for Nuclear Thermal Propulsion Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this Phase I SBIR program is to develop polymer derived rare earth silicate nanocomposite environmental barrier coatings (EBC) for providing...

  4. Polymer Derived Rare Earth Silicate Nanocomposite Protective Coatings for Nuclear Thermal Propulsion Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Leveraging a rapidly evolving state-of-the-art technical base empowered by Phase I NASA SBIR funding, NanoSonic's polymer derived rare earth silicate EBCs will...

  5. Anisotropic ferromagnetic polymer: A first step for their implementation in microfluidic systems

    Directory of Open Access Journals (Sweden)

    Damien Le Roy

    2016-05-01

    Full Text Available Here we report on the influence of anisotropic microstructure on the performances of magnetically soft micro-patterns intended to integrate microfluidic systems. These micro-patterns are made of a composite obtained by mixing carbonyl iron particles with polydimethylsiloxane, which offers practical integration advantages. We investigated a wide range of magnetic particle loadings, from 10wt% to 83wt%, reaching magnetization as high as 630 kA/m. A homogeneous field was applied during the polymer’s cross-linking phase so that to obtain a 1D arrangement of the particles in the solidified polymer, along the field direction. Here we present the results obtained for square-based micro-pillars prepared under a magnetic field applied along one of its diagonal. We assessed the magnetic anisotropy owing to the particles’ spatial arrangement by comparing the magnetization processes along the two diagonals of the micro-pillar’s base. The magnetic susceptibilities along the two directions differ from a factor greater than three. The results can be described in terms of high aspect ratio and porous magnetic agglomerates.

  6. Inulin-based polymer coated SPIONs as potential drug delivery systems for targeted cancer therapy.

    Science.gov (United States)

    Scialabba, C; Licciardi, M; Mauro, N; Rocco, F; Ceruti, M; Giammona, G

    2014-11-01

    This paper deal with the synthesis and characterization of PEGylated squalene-grafted-inulin amphiphile capable of self-assembling and self-organizing into nanocarriers once placed in aqueous media. It was exploited as coating agent for obtaining doxorubicin loaded superparamagnetic iron oxide nanoparticles (SPIONs) endowed with stealth like behavior and excellent physicochemical stability. Inulin was firstly modified in the side chain with primary amine groups, followed in turn by conjugation with squalenoyl derivatives through common amidic coupling agents and PEGylation by imine linkage. Polymer coated SPIONs were so obtained by spontaneous self-assembling of inulin copolymer onto magnetite surface involving hydrophobic-hydrophobic interactions between the metallic core and the squalene moieties. The system was characterized in terms of hydrodynamic radius, zeta potential, shape and drug loading capacity. On the whole, the stealth-like shell stabilized the suspension in aqueous media, though allowing the release of the doxorubicin loaded in therapeutic range. The cytotoxicity profile on cancer (HCT116) cell line and in vitro drug uptake were evaluated both with and without an external magnetic field used as targeting agent and uptake promoter, displaying that magnetic targeting implies advantageous therapeutic effects, that is amplified drug uptake and increased anticancer activity throughout the tumor mass.

  7. A review of integrating electroactive polymers as responsive systems for specialized drug delivery applications.

    Science.gov (United States)

    Pillay, Viness; Tsai, Tong-Sheng; Choonara, Yahya E; du Toit, Lisa C; Kumar, Pradeep; Modi, Girish; Naidoo, Dinesh; Tomar, Lomas K; Tyagi, Charu; Ndesendo, Valence M K

    2014-06-01

    Electroactive polymers (EAPs) are promising candidate materials for the design of drug delivery technologies, especially in conditions where an "on-off" drug release mechanism is required. To achieve this, EAPs such as polyaniline, polypyrrole, polythiophene, ethylene vinyl acetate, and polyethylene may be blended into responsive hydrogels in conjunction with the desired drug to obtain a patient-controlled drug release system. The "on-off" drug release mechanism can be achieved through the environmental-responsive nature of the interpenetrating hydrogel-EAP complex via (i) charged ions initiated diffusion of drug molecules; (ii) conformational changes that occur during redox switching of EAPs; or (iii) electroerosion. These release mechanisms are not exhaustive and new release mechanisms are still under investigation. Therefore, this review seeks to provide a concise incursion and critical overview of EAPs and responsive hydrogels as a strategy for advanced drug delivery, for example, controlled release of neurotransmitters, sulfosalicyclic acid from cross-linked hydrogel, and vaccine delivery. The review further discusses techniques such as linear sweep voltammetry, cyclic voltammetry, impedance spectroscopy, and chronoamperometry for the determination of the redox capability of EAPs. The future implications of the hydrogel-EAP composites include, but not limited to, application toward biosensors, DNA hybridizations, microsurgical tools, and miniature bioreactors and may be utilized to their full potential in the form of injectable devices as nanorobots or nanobiosensors.

  8. Using surface interactions to tune adhesion and morphology in polymer systems

    Science.gov (United States)

    Asoo, Beverly Yoshiko

    Surface interactions govern physical behavior at polymer interfaces. The first part of this dissertation focuses on surface interactions and the adhesion between PET and gelatin, two surfaces that would not normally adhere with each other. However, by plasma-treating the PET, the two materials can be joined. The fracture energy of this PET/gelatin interface was measured using the asymmetric double cantilever beam (ACDB) technique and it was determined that increasing the treatment time and power of the plasma on PET increased the fracture energy of the interface. Additionally, due to the hydroscopic nature of gelatin, higher relative humidity during testing also increased the interfacial fracture energy. The second part of the dissertation examines surface interactions in polymer blends. Thermoplastic blends enjoy large-scale commercial appeal for both engineering and economic reasons. Blends can be tuned to improve various materials properties, such as elastic modulus or impact resistance. Although blends offer many advantageous benefits, the thermodynamics of these blends are not fully understood, since each particular blend has its own behavior and morphology based on processing conditions. Even more complicated morphologies could be obtained by adding filler particles. The main interest of this area of research is the formation of co-continuous morphologies by adding particles in a blend of two homopolymers. In our system, one of the homopolymers coated the particles. At very high particle concentrations, the colloidal particles facilitated the transport of aqueous solutions. This research explored the role of particle concentration in the blends, as well as the role of concentration of the homopolymer that wets the particles. In order to study the morphology and determine the percolation threshold, the resulting microstructures were imaged in real space using techniques such as transmission electron microscopy, scanning electron microscopy, and confocal

  9. 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.

  10. Biodegradable Polymers

    OpenAIRE

    Isabelle Vroman; Lan Tighzert

    2013-01-01

    Biodegradable materials are used in packaging, agriculture, medicine and other areas. In recent years there has been an increase in interest in biodegradable polymers. Two classes of biodegradable polymers can be distinguished: synthetic or natural polymers. There are polymers produced from feedstocks derived either from petroleum resources (non renewable resources) or from biological resources (renewable resources). In general natural polymers offer fewer advantages than synthetic polymers. ...

  11. Wetting and dispersion in ceramic/polymer melt injection molding systems

    Energy Technology Data Exchange (ETDEWEB)

    Sacks, M.D.; Williams, J.W.; Batich, C.D.

    1985-11-01

    The major goal of this program is to achieve an improved understanding of the factors influencing dispersion of ceramic particles in polymer melts. In general, there are three requirements in the dispersion of a powder in a liquid medium (e.g., a polymer melt): (1) wetting of the powder by the liquid; (2) breaking up powder agglomerates; and (3) maintaining the dispersed state (e.g., avoiding particle coagulation). Work has been initiated in each of these areas. Preliminary results are described.

  12. Influence of D/A ratio on photovoltaic performance of a highly efficient polymer solar cell system.

    Science.gov (United States)

    Guo, Xia; Zhang, Maojie; Tan, Jiahui; Zhang, Shaoqing; Huo, Lijun; Hu, Wenping; Li, Yongfang; Hou, Jianhui

    2012-12-18

    A new copolymer PIDTDTQx based on indacenodithiophene and quinoxaline is synthesized and characterized. The correlation between the D/A ratio, mobility, and photovoltaic properties, as well as morphology of the D/A blend based on a PIDTDTQx:PC(70) BM system is investigated. The power conversion efficiency of the polymer solar cells based on PIDTDTQx/PC(70) BM (1:4, w/w) reaches 7.51%.

  13. EFFECT OF PERMEABLE VESSEL CLOSURE AND GELLING AGENT ON REDUCTION OF HYPERHYDRICITY IN IN VITRO CULTURE OF CARNATION

    Directory of Open Access Journals (Sweden)

    B. Winarto

    2016-10-01

    Full Text Available Hyperhydricity, an abnormal morphological appearance and physiologicalfunction, is an important problem in carnation tissue culture. The problem causes premature flowering, high occurrence of abnormal shoots, difficulty in transferring hyperhydric plantlets to soil, and low survival rate of plantlets. High relative humidity and the water potential are considered as the key factors involved in the abnormality. Furthermore, permeable culture vessel and gelling agent were assured to be high potential treatment to eliminate it. Objective of this research was to reduce  hyperhydricity in regenerants of carnation using different permeable vessel closures and gelling agents and to assess the multiplication and  acclimatization abilities of recovered shoots. Experiment was arranged in randomized complete block design with four replications. First factor was different types of closure, i.e. cotton wool, plastic wrap, parafilm and aluminium foil, while second one was gelling agents, i.e. bacto agar, phytagel, swallow agar, and Type 900 agar. The recovered shoots were then multiplied, rooted, and acclimatized. The results showed that hyperhydricity was successfully reduced by applying permeable closure (cotton wool and plastic wrap in combination with Type 900 agar. The combination of plastic wrap and Type 900 agar was the most appropriate treatment in reducing hyperhydricity and producing good quality shoots. The treatment reduced the problem down to 23% of total condition of hyperhydricity (100% and increased leaf chlorophyll content from 0.0883 to 0.1288 mg mg-1. The plastic wrap was easily applied and cheaper material compared to cotton wool. The recovered shoots were able to produce 1-3 healthy axillary shoots and easily rooted on half-strength MS. The recovered plantlets were simply acclimatized with survival rate up to 100% on kossas peat + soil (1:1, v/v and flowered 4-5 months after acclimatization with decreasing in number and size of flower.

  14. The effect of water-swelling polymer composition on radiocesium transfer in 'water - soil - plant' system

    Energy Technology Data Exchange (ETDEWEB)

    Tavakalyan, N.; Sergeeva, S.; Voskanyan, P. [Yerevan Institute ' Plastpolymer' Yerevan, 0007, 127 Arshacunats (Armenia); Tadevosyan, A.; Pyuskyulyan, K. [Institute of Hydroponics Problems NAS RA, Yerevan, 0082, 108 Noragyugh (Armenia); Mihranyan, A. [Division of Materials Science, Luleaa University of Technology, LuleAa SE-971 87 (Sweden); Tsuruoka, S. [Research Center for Exotic Nanocarbons, Shinshu University, Nagano,380-8553,4-17-1 Wakasato (Japan)

    2014-07-01

    Due to the relatively long half-life (T{sub 1/2} = 30 years) and high solubility {sup 137}Cs presents a serious threat to the environment. The study on radioactive cesium transfer into plants and its distribution in different parts of plants (roots, stems and leaves) is among the tasks of agricultural radioecology. The problem has become especially urgent in connection with the accident at Fukushima nuclear power plant. The present work describes potential countermeasures to regulate radiocesium transfer from soil to agricultural plants. As countermeasure the use polymer hydrogels is offered. Water-swelling polymers are of great interest for their practical application as effective absorbents of humidity at growth of agricultural plants. Composite polymer hydrogels containing an inorganic phase are of special interest, as numerous inorganic fillers exhibit the ability to absorb radionuclides. Optimal samples of hydrogels based on ammonium acrylate with good water-swelling and water-retention were obtained. Samples with the same polymer matrix - ammonium acrylate - and such fillers as silica gel, synthetic aluminosilicate, bentonite and zeolite from Armenian deposits were used. Developed gels with and without fillers are applicable for multiple uses in the processes of water sorption and desorption. For preliminary assessment of radiocesium migration in 'water - soil- plant' system we studied sorption of {sup 137}Cs and {sup 134}Cs from water. In the experiments, water with the specific radioactivity (1.86-4.38)x10{sup 4} Bq/L was used for {sup 137}Cs, while for {sup 134}Cs we used (2.175- 3.41)x10{sup 4} Bq/L water. Low-background gamma spectrometer with pure Ge detector and supporting 'GENIE' software were used for measurements. Non-filled gels of ammonium acrylate actually did not absorb radiocesium from water. Cesium sorption by filled gels of ammonium acrylate depended on the filler type and quantity. The optimal quantity of filler was

  15. Molecularly imprinted polymer based micromechanical cantilever sensor system for the selective determination of ciprofloxacin.

    Science.gov (United States)

    Okan, Meltem; Sari, Esma; Duman, Memed

    2017-02-15

    The main objective of this study is to develop molecularly imprinted polymer (MIP) based micromechanical cantilever sensor system that has high specificity, fast response time and is easily applicable by user for the detection of ciprofloxacin (CPX) molecule in water resources. Highly specific CPX imprinted nanoparticles were synthesized by miniemulsion polymerization technique. The average size of the synthesized nanoparticles was measured about 160nm with high monodispersivity. Covalent and monolayer binding of the MIP nanoparticles on cantilevers was provided by EDC/NHS activation. Validation of the developed cantilever nanosensor was performed in air with dip-and-dry technique by employing the dynamic sensing mode. According to the results obtained, micromechanical cantilever sensor system worked linearly for the concentration range of 1.5-150.9μM. This concentration range resulted with 18.4-48.9pg mass load on the MIP modified cantilever. The sensitivity of the developed sensor was calculated as 2.6Hz/pg. To control the specificity of MIPs, a different antibiotic enrofloxacin (ENF), with a similar physical and chemical structure with CPX, was used, which showed 7 folds low binding affinity. The developed highly specific microcantilever sensor has a response time of approximately 2min and is reusable up to 4 times. The results indicate that the MIP based AFM nanosensor has high sensitivity for the CPX molecule. This combination of MIP nanoparticles with micromechanical sensors is one of the pioneer studies in the mass sensing applications. This fast, low cost and highly sensitive CPX specific MIP nanoparticle based nanosensor developed in this research have the potential to pave the way for further studies. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Low velocity impact response and damage evolution in unreinforced resin systems and self-repairing polymer matrix composites

    Science.gov (United States)

    Motuku, Molefi

    The low velocity impact response and damage evolution in unreinforced polymer matrices, conventional polymer matrix composites, and self-repairing polymer matrix composites was investigated. The impact response study of unreinforced matrices and conventional laminates was undertaken because the failure initiation energies, threshold energy levels, failure characteristics and damage evolution in both the matrix material (unreinforced resin plaques) and the composite are intrinsic to proper design of a self-repairing composite. The self-repairing concept was investigated due to its attractive potential to alleviate damage problems in polymer matrix composites. Self-repairing composites, which fall under the category of passive smart polymer composites, have the potential to self repair both micro- and macro-damage resulting from impacts as well as non-impact loading. The self-repairing mechanism is achieved through the incorporation of hollow fibers in addition to the normal solid reinforcing fibers. The hollow fibers store the damage-repairing solution or chemicals that are released into the matrix or damaged zone upon fiber failure to repair and/or arrest damage progression. The room temperature low velocity impact response and damage evolution in DERAKANE 411-350 and 411-C50 vinyl ester unreinforced resin systems was investigated as a function of impact energy level, sample thickness, matrix material and catalyst system. The low velocity impact response of conventional and self-repairing glass reinforced polymer composites was investigated by addressing the fabrication and some of the parameters that influence their response to low velocity impact loading. Specific issues addressed by this study include developing a process to fabricate self-repairing laminates, processing quality; selection of storage material for the repairing solution; release and transportation of repairing solution; the effect of the number, type and spatial distribution of the repairing

  17. Downstream processing of polymer-based amorphous solid dispersions to generate tablet formulations.

    Science.gov (United States)

    Démuth, B; Nagy, Z K; Balogh, A; Vigh, T; Marosi, G; Verreck, G; Van Assche, I; Brewster, M E

    2015-01-01

    Application of amorphous solid dispersions (ASDs) is considered one of the most promising approaches to increase the dissolution rate and extent of bioavailability of poorly water soluble drugs. Such intervention is often required for new drug candidates in that enablement, bioavailability is not sufficient to generate a useful product. Importantly, tableting of ASDs is often complicated by a number of pharmaceutical and technological challenges including poor flowability and compressibility of the powders, compression-induced phase changes or phase separation and slow disintegration due to the formation of a gelling polymer network (GPN). The design principles of an ASD-based system include its ability to generate supersaturated systems of the drug of interest during dissolution. These metastable solutions can be prone to precipitation and crystallization reducing the biopharmaceutical performance of the dosage form. The main aim of the research in this area is to maintain the supersaturated state and optimally enhance bioavailability, meaning that crystallization should be delayed or inhibited during dissolution, as well as in solid phase (e.g., during manufacturing and storage). Based on the expanding use of ASD technology as well as their downstream processing, there is an acute need to summarize the results achieved to this point to better understand progress and future risks. The aim of this review is to focus on the conversion of ASDs into tablets highlighting results from various viewpoints.

  18. Experiment of detonation characteristics of gelled gasolines in pulse detonation engine%凝胶汽油在脉冲爆轰发动机中的爆轰特性实验

    Institute of Scientific and Technical Information of China (English)

    胡洪波; 翁春生; 白桥栋; 杨建鲁

    2014-01-01

    An experimental system of pulse detonation rocket engine using gelled fuels was established to explore the feasibility of application of gelled fuels on pulse detonation engines.The hot state tests were accomplished on multi-cycle pulse detonation rock-et engine at different oxygen concentration and supply conditions of gelled fuels.The influences of oxygen concentration and fuel sup-ply conditions on pressure and wave propagation velocity of detonation wave were analyzed. The experimental results indicate that pulse detonation rocket engine can work stably with gelled fuels.With 42% oxygen in filling gases and injection pressure coefficients of fuel and atomizing air at 2.5 and 1,the average value of detonation pressure and wave velocity were 2.02 MPa and 1 124 m/s re-spectively.The pressure and wave velocity of detonation increase with oxygen addition under the same fuel supply conditions.The re-sults have some significant references for application investigation on gelled fuels and pulse detonation engines.%为探索凝胶燃料在脉冲爆轰发动机中应用的可行性,设计了凝胶汽油脉冲爆轰火箭发动机实验系统。对不同氧含量和凝胶汽油供给工况下的多循环脉冲爆轰发动机进行了热态实验,分析了氧含量和燃料供给工况对爆轰段爆轰压力和波传播速度的影响。实验结果表明,使用凝胶汽油的脉冲爆轰火箭发动机能稳定工作;在氧气质量百分比为42%、凝胶汽油/雾化空气喷射压力系数为2.5/1工况下,距离发动机点火位置770 mm处的爆轰压力均值为2.02 MPa,爆轰波速度均值为1124 m/s。在相同凝胶汽油供给条件下,增加氧含量能够获得更大的爆轰压力和爆轰波速度。研究结果对凝胶燃料和脉冲爆轰发动机应用研究具有参考意义。

  19. Floating drug delivery of a locally acting H2-antagonist: an approach using an in situ gelling liquid formulation.

    Science.gov (United States)

    Rohith, Ganapati; Sridhar, Bhimagoni Keshavamurthy; Srinatha, Anegundha

    2009-09-01

    In the present work, a gastroretentive in situ gelling liquid formulation for controlled delivery of ranitidine was formulated using sodium alginate (low, medium and high viscosity grades), calcium carbonate (source of cations) and ranitidine. Prepared formulations were evaluated for viscosity, buoyancy lag time and buoyancy duration, drug content and in vitro drug release. Formulation variables such as concentration of sodium alginate, calcium carbonate and drug significantly affected the formulation viscosity, floating behavior and in vitro drug release. Analysis of the release pattern showed that the drug release from in situ gel followed a diffusion mechanism.

  20. Banquet Speech at the Singapore Conference in Honour of Murray Gell-Mann on His 80th Birthday

    Science.gov (United States)

    Yang, Chen Ning

    2013-05-01

    It was about 60 years ago in 1951 that I first met in Princeton, at the Institute for Advanced Study, our Honoree tonight, Murray Gell-Mann. In the intervening 60 years, man's understanding of the fundamental structure of matter has made great historic advances. At this wonderful Conference, we have the opportunity to review some of these historic advances. It is a little like looking over an old album of memorable photographs in one's lifetime. In many of these photographs, Murray appears either in the foreground, or as the photographer snapping the picture. We know he is pleased with the album...

  1. Effect of acrylic polymers on physical parameters of spheronized pellets using an aqueous coating system

    Directory of Open Access Journals (Sweden)

    Akhter Afsana

    2009-01-01

    Full Text Available The aim of this study was to develop ambroxol hydrochloride sustained release pellets by an extrusion-spheronization technique and subsequent coating with acrylic polymers. Acrylic polymers like Eudragit RL 30 D, Eudragit RS 30 D and Eudragit NE 30 D were used as release retarding coating polymers. The release retarding capability of these polymers was also investigated. In each case, 10% polymer on dry basis was loaded. The flow property, surface roughness as well as the drug release behavior of the pellets was found to be the subject of types of polymers. About 35% drug was released at the first hour in 0.1N HCl media (pH 1.2 from Eudragit RL 30 D-coated pellets but from Eudragit RS 30 D and Eudragit NE 30 D-coated pellets, only 13.75 and 2.43% drug was released, respectively. In buffer media (pH 6.8, about 54% drug was released at the first hour from Eudragit RL 30 D-coated pellets but only 64% drug was released at 10 h. From Eudragit RL 30 D- and Eudragit NE 30 D-coated pellets only 7.28 and 1.14% drug was released at 1 h, respectively, but about 5.14 and 5.86 h was required for 50% drug release from these two polymers and about 80% drug was released at 10 h. The functional groups present in the polymeric films played a significant role on in vitro release kinetics of the drug from the coated pellets. Different kinetic models like zero order, first order and Higuchi were used for fitting the drug release pattern. The Higuchi model was the best fitted for ambroxol release from the coated pellets. The drug release mechanism was derived with Korsmeyer equation.

  2. Control and experimental characterization of a methanol reformer for a 350W high temperature polymer electrolyte membrane fuel cell system

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen; Jensen, Hans-Christian Becker

    High temperature polymer electrolyte membrane(HTPEM) fuel cells offer many advantages due to their increased operating tempera-tures compared to similar Nafion-based membrane tech-nologies, that rely on the conductive abilities of liquid water. The polybenzimidazole (PBI) membranes are especially...... suited for reformer systems, where high CO tolerance is required. This enables the use fuels based on e.g. liquid alcohols. This work presents the control strategies of a methanol refoermer for a 350W HTPEM FC system. The system examined is the Serenergy H3-350 Mobile Battery Charger, an integrated...

  3. Modeling the vapor-liquid equilibria of polymer-solvent mixtures: Systems with complex hydrogen bonding behavior

    DEFF Research Database (Denmark)

    Tsivintzelis, Ioannis; Kontogeorgis, Georgios

    2009-01-01

    The vapor–liquid equilibria of binary polymer–solvent systems was modeled using the Non-Random Hydrogen Bonding (NRHB) model. Mixtures of poly(ethylene glycol), poly(propylene glycol), poly(vinyl alcohol) and poly(vinyl acetate) with various solvents were investigated, while emphasis was put...... on hydrogen bonding systems, in which functional groups of the polymer chain can self-associate or cross-associate with the solvent molecules. Effort has been made to explicitly account for all hydrogen bonding interactions. The results reveal that the NRHB model offers a flexible approach to account...... the complexity of the examined systems....

  4. INFLUENCE OF MEDIA GELLING AGENTS ON ROOT BIOMASS AND IN VITRO VA-MYCORRfflZAL SYMBIOSIS OF CARROT WITH GIGASPORA MARGARITA

    Directory of Open Access Journals (Sweden)

    ANJALI VERMA

    1997-01-01

    Full Text Available An in vitro study with Ri-TDNA transformed roots of carrot (Daucus carota was carried out to evaluate the role of macro-elements contributed as impurities in the gelling agent (phytagel over and above those present in the minimal (M medium. Production of root biomass was taken as a measure to quantify the influence of macro-elements added to the minimal medium. The levels of phosphorus when adjusted to 1.19 mg/1 and 1.09 mg/l, lead to dry root biomass production at par with the control. Attempts made to lower the amount of impurities in phytagel by de-ionization using different alkalies, proved NaOH to give the best results in terms of relatively high amount of root biomass. In an in vitro dual culture system with carrot as host and Gigaspora margarita as the vesicular-arbuscular mycorrhizal fungus, phytagel impurities helped to produce maximum number of infection units and auxiliary cells when phytagel was added to the minimal medium.

  5. Stiffness and strength of fiber reinforced polymer composite bridge deck systems

    Science.gov (United States)

    Zhou, Aixi

    This research investigates two principal characteristics that are of primary importance in Fiber Reinforced Polymer (FRP) bridge deck applications: STIFFNESS and STRENGTH. The research was undertaken by investigating the stiffness and strength characteristics of the multi-cellular FRP bridge deck systems consisting of pultruded FRP shapes. A systematic analysis procedure was developed for the stiffness analysis of multi-cellular FRP deck systems. This procedure uses the Method of Elastic Equivalence to model the cellular deck as an equivalent orthotropic plate. The procedure provides a practical method to predict the equivalent orthotropic plate properties of cellular FRP decks. Analytical solutions for the bending analysis of single span decks were developed using classical laminated plate theory. The analysis procedures can be extended to analyze continuous FRP decks. It can also be further developed using higher order plate theories. Several failure modes of the cellular FRP deck systems were recorded and analyzed through laboratory and field tests and Finite Element Analysis (FEA). Two schemes of loading patches were used in the laboratory test: a steel patch made according to the ASSHTO's bridge testing specifications; and a tire patch made from a real truck tire reinforced with silicon rubber. The tire patch was specially designed to simulate service loading conditions by modifying real contact loading from a tire. Our research shows that the effects of the stiffness and contact conditions of loading patches are significant in the stiffness and strength testing of FRP decks. Due to the localization of load, a simulated tire patch yields larger deflection than the steel patch under the same loading level. The tire patch produces significantly different failure compared to the steel patch: a local bending mode with less damage for the tire patch; and a local punching-shear mode for the steel patch. A deck failure function method is proposed for predicting the

  6. Experimental research on characteristic of start-up pressure wave propagation in gelled crude oil by large-scale flow loop

    Institute of Scientific and Technical Information of China (English)

    崔秀国; 艾慕阳; 姜保良; 霍连风; 张立新

    2008-01-01

    In order to research start-up pressure wave propagation mechanism and determine pressure wave speed in gelled crude oil pipelines accurately,experiment of Large-scale flow loop was carried out.In the experiment,start-up pressure wave speeds under various operation conditions were measured,and effects of correlative factors on pressure wave were analyzed.The experimental and theoretical analysis shows that thermal shrinkage and structural properties of gelled crude oils are key factors influencing on start-up pressure wave propagation.The quantitative analysis for these effects can be done by using volume expansion coefficient and structural property parameter of gelled crude oil.A new calculation model of pressure wave speed was developed on the basis of Large-scale flow loop experiment and theoretical analysis.

  7. Shape memory polymer medical device

    Science.gov (United States)

    Maitland, Duncan; Benett, William J.; Bearinger, Jane P.; Wilson, Thomas S.; Small, IV, Ward; Schumann, Daniel L.; Jensen, Wayne A.; Ortega, Jason M.; Marion, III, John E.; Loge, Jeffrey M.

    2010-06-29

    A system for removing matter from a conduit. The system includes the steps of passing a transport vehicle and a shape memory polymer material through the conduit, transmitting energy to the shape memory polymer material for moving the shape memory polymer material from a first shape to a second and different shape, and withdrawing the transport vehicle and the shape memory polymer material through the conduit carrying the matter.

  8. Using Selected Chemical and Physical Factors to Cross-link a BioCo Polymer Binder - Mineral Matrix System

    Directory of Open Access Journals (Sweden)

    B. Grabowska

    2013-04-01

    Full Text Available This publication describes research on the course of the process of cross-linking new BioCo polymer binders - in the form of water-based polymer compositions of poly(acrylic acid or poly(sodium acrylate/modified polysaccharide - using selected physical and chemical factors. It has been shown that the type of cross-linking factor used influences the strength parameters of the moulding sand. The crosslinking factors selected during basic research make it possible to obtain sand strengths similar to those of samples of sands bonded with commercial binders. Microwave radiation turned out to be the most effective cross-linking factor in a binder-matrix system. It was proven that adsorption in the microwave radiation field leads to the formation of polymer lattices with hydrogen bonds which play a major role in maintaining the formed cross-linked structures in the binder-matrix system. As a result, the process improves the strength parameters of the sand, whereas the hardening process in a microwave field significantly shortens the setting time.

  9. On the molecular anisotropy of liquid crystalline and flexible polymer systems

    Science.gov (United States)

    van Horn, Brett L.

    The demand for products of ever increasing quality or for novel applications has required increasing attention to or manipulation of the anisotropy of manufactured parts. Oriented plastics are used everywhere from recording film to automotive body parts to monofilament fishing line. Liquid crystals are also used in a wide array of applications including their dominance in the flat panel display industry, color changing temperature sensors, and woven bullet resistant fabrics. Anisotropy can also be detrimental, for instance sometimes leading to poor fracture resistance or low yield stress along specific directions. Controlling and measuring anisotropy of materials has become increasingly important, but doing so is wrought with challenges. Measuring physical properties of isotropic liquids, such as water or most oils can be done in a straightforward fashion. Their viscosities and densities, for example, have unique values under a given set of conditions. With anisotropic fluids, like liquid crystals, the viscosity, for instance, will not only depend upon temperature, concentration, etc. but also upon the direction of observation, degree of anisotropy, source of anisotropy, and so forth. This added degree of complexity complicates our ability to define the state of the material at which the measurements are made and generally necessitates the use of more sophisticated measurement strategies or techniques. This work presents techniques and tools for investigating anisotropy in liquid crystalline and stretched polymeric systems. Included are the use of conoscopy for the determination of birefringence and orientation of nematic liquid crystals and stretched polymers, the shear response of flow aligning nematic liquid crystal monodomains, and the design of a novel linear rheometer that allows for in situ optical or scattering investigations.

  10. Natural-Synthetic Hybrid Polymers Developed via Electrospinning: The Effect of PET in Chitosan/Starch System

    Directory of Open Access Journals (Sweden)

    Carlos Velasco-Santos

    2011-03-01

    Full Text Available Chitosan is an amino polysaccharide found in nature, which is biodegradable, nontoxic and biocompatible. It has versatile features and can be used in a variety of applications including films, packaging, and also in medical surgery. Recently a possibility to diversify chitosan properties has emerged by combining it with synthetic materials to produce novel natural-synthetic hybrid polymers. We have studied structural and thermophysical properties of chitosan + starch + poly(ethylene terephthalate (Ch + S + PET fibers developed via electrospinning. Properties of these hybrids polymers are compared with extant chitosan containing hybrids synthesized by electrospinning. Molecular interactions and orientation in the fibers are analyzed by infrared and Raman spectroscopies respectively, morphology by scanning electron microscopy and thermophysical properties by thermogravimetric analysis and differential scanning calorimetry. Addition of PET to Ch + S systems results in improved thermal stability at elevated temperatures.

  11. Natural-synthetic hybrid polymers developed via electrospinning: the effect of PET in chitosan/starch system.

    Science.gov (United States)

    Espíndola-González, Adolfo; Martínez-Hernández, Ana Laura; Fernández-Escobar, Francisco; Castaño, Victor Manuel; Brostow, Witold; Datashvili, Tea; Velasco-Santos, Carlos

    2011-01-01

    Chitosan is an amino polysaccharide found in nature, which is biodegradable, nontoxic and biocompatible. It has versatile features and can be used in a variety of applications including films, packaging, and also in medical surgery. Recently a possibility to diversify chitosan properties has emerged by combining it with synthetic materials to produce novel natural-synthetic hybrid polymers. We have studied structural and thermophysical properties of chitosan + starch + poly(ethylene terephthalate) (Ch + S + PET) fibers developed via electrospinning. Properties of these hybrids polymers are compared with extant chitosan containing hybrids synthesized by electrospinning. Molecular interactions and orientation in the fibers are analyzed by infrared and Raman spectroscopies respectively, morphology by scanning electron microscopy and thermophysical properties by thermogravimetric analysis and differential scanning calorimetry. Addition of PET to Ch + S systems results in improved thermal stability at elevated temperatures.

  12. Biodegradable Polymers

    Directory of Open Access Journals (Sweden)

    Isabelle Vroman

    2009-04-01

    Full Text Available Biodegradable materials are used in packaging, agriculture, medicine and other areas. In recent years there has been an increase in interest in biodegradable polymers. Two classes of biodegradable polymers can be distinguished: synthetic or natural polymers. There are polymers produced from feedstocks derived either from petroleum resources (non renewable resources or from biological resources (renewable resources. In general natural polymers offer fewer advantages than synthetic polymers. The following review presents an overview of the different biodegradable polymers that are currently being used and their properties, as well as new developments in their synthesis and applications.

  13. Polymer electronics

    CERN Document Server

    Hsin-Fei, Meng

    2013-01-01

    Polymer semiconductor is the only semiconductor that can be processed in solution. Electronics made by these flexible materials have many advantages such as large-area solution process, low cost, and high performance. Researchers and companies are increasingly dedicating time and money in polymer electronics. This book focuses on the fundamental materials and device physics of polymer electronics. It describes polymer light-emitting diodes, polymer field-effect transistors, organic vertical transistors, polymer solar cells, and many applications based on polymer electronics. The book also disc

  14. 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.

  15. All-Polymer Microfluidic Systems with integrated Nanostructures for Cell Handling

    DEFF Research Database (Denmark)

    Matschuk, Maria

    There is an increasing need for mass-production of nanostructures with high precision at polymer surfaces, for example to reduce the reflection of light, to reduce the adhesion of smudge, for optical data storage (e.g. Blu-ray discs), and for biological applications. In this project the effects...... of the polymer melt, interfacial effects like wetting and friction play a major role in injection molding of high aspect ratio nanostructures. The interfacial energy between mold and polymer needs to allow filling as well as demolding which are opposing properties: On the one hand, insufficient wetting...... lithography was found to improve the replication quality substantially. Large scale defects of the overall patterned surface were fully removed while regular nanoscale defects decreased significantly. Optimized injection molding conditions allowed the replication of highly ordered nanostructures of controlled...

  16. Further Improvement and System Integration of High Temperature Polymer Electrolyte Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Li, Qingfeng; Jensen, Jens Oluf

    ) integration of the HT-PEMFC stack with these compatible subunits. The main goal of the project is a 2kWel HT-PEMFC stack operating in a temperature range of 150-200°C, with a single cell performance target of 0.7 A/cm² at a cell voltage around 0.6 V. The target durability is more than 5,000 hours....... A hydrocarbon reformer and a catalytic burner are to be developed and integrated with the stack. The key issue of the project is development and improvement of the temperature-resistant polymer membranes with respect to durability, conductivity, mechanical and other properties. For this purpose, basic polymers...... will be first synthesized and optimized. Different routes to functionalize the polymers will be explored to increate proton conductivity....

  17. Sustainable design and manufacturing of multifunctional polymer nanocomposite coatings: A multiscale systems approach

    Science.gov (United States)

    Xiao, Jie

    Polymer nanocomposites have a great potential to be a dominant coating material in a wide range of applications in the automotive, aerospace, ship-making, construction, and pharmaceutical industries. However, how to realize design sustainability of this type of nanostructured materials and how to ensure the true optimality of the product quality and process performance in coating manufacturing remain as a mountaintop area. The major challenges arise from the intrinsic multiscale nature of the material-process-product system and the need to manipulate the high levels of complexity and uncertainty in design and manufacturing processes. This research centers on the development of a comprehensive multiscale computational methodology and a computer-aided tool set that can facilitate multifunctional nanocoating design and application from novel function envisioning and idea refinement, to knowledge discovery and design solution derivation, and further to performance testing in industrial applications and life cycle analysis. The principal idea is to achieve exceptional system performance through concurrent characterization and optimization of materials, product and associated manufacturing processes covering a wide range of length and time scales. Multiscale modeling and simulation techniques ranging from microscopic molecular modeling to classical continuum modeling are seamlessly coupled. The tight integration of different methods and theories at individual scales allows the prediction of macroscopic coating performance from the fundamental molecular behavior. Goal-oriented design is also pursued by integrating additional methods for bio-inspired dynamic optimization and computational task management that can be implemented in a hierarchical computing architecture. Furthermore, multiscale systems methodologies are developed to achieve the best possible material application towards sustainable manufacturing. Automotive coating manufacturing, that involves paint spay and

  18. A quasi-direct methanol fuel cell system based on blend polymer membrane electrolytes

    DEFF Research Database (Denmark)

    Li, Qingfeng; Hjuler, Hans Aage; Hasiotis, C.

    2002-01-01

    , compared to less than 100 ppm CO for the Nafion-based technology at 80degrees C. The high CO tolerance makes it possible to use the reformed hydrogen directly from a simple methanol reformer without further CO removal. That both the fuel cell and the methanol reformer operate at temperatures around 200......On the basis of blend polymer electrolytes of polybenzimidazole and sulfonated polysulfone, a polymer electrolyte membrane fuel cell was developed with an operational temperature up to 200degrees C. Due to the high operational temperature, the fuel cell can tolerate 1.0-3.0 vol % CO in the fuel...

  19. Investigation of a polymer-dispersed liquid crystal system by NMR diffusometry and relaxometry

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Mingxue

    2013-02-26

    Polymer-dispersed liquid crystals (PDLCs) are polymer composites containing a dispersion of liquid crystal droplets in polymer networks. PDLCs have attracted much attention due to their unique properties and potential usage. The properties of PDLCs depend on the degree of phase separation and the size of liquid crystal droplets. To investigate the structure will help us to better understand and optimize PDLCs.The main aim of this PhD thesis was to investigate PDLCs by NMR techniques. Diffusion constants and spin-lattice relaxation times in the laboratory (T{sub 1}) and rotating frame (T{sub 1{rho}}) were measured for PDLCs as well as precursor mixtures based on the trifunctional monomer trimethylolpropane triacrylate (TMPTA) and the commercial nematic mixture E7. The variation of the main dipolar splitting of {sup 1}H spectra with increasing temperature was analyzed to obtain the nematic-to-isotropic phase transition temperature and the nematic order parameter of E7 and, for comparison, the nematic liquid crystal 5CB.Diffusion constants in TMPTA/E7 mixtures, measured by pulsed-field gradient NMR, increase for both E7 and TMPTA as the mass fraction of E7 increases, due to the lower viscosity of E7. E7 in the PDLC diffuses more slowly than in the bulk because of the hindrance by the polymer matrix. T{sub 1} and T{sub 1{rho}} relaxation times in the liquid or liquid-crystalline phases of TMPTA and bulk E7 are higher than in the PDLC and the pure polymer, due to the lower mobility in the polymer samples. T{sub 1{rho}} in the PDLC is even shorter than in the pure polymer, indicating an anti-softening effect caused by E7 molecules. In bulk E7, the well-ordered rod-like molecules exhibit a unique H-C dipolar coupling, which leads to oscillations in the cross-polarization curve. However, in the PDLC, the anchoring effect at the boundary between the polymer and LC droplets disturbs the molecular order resulting in a smooth cross polarization curve.

  20. Silver-containing polymer composition used in spacecraft and semiconductor optoelectronics control systems

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, A. A., E-mail: alexchemtsu@rambler.ru; Tuev, V. I., E-mail: tvi-retem@main.tusur.ru [Tomsk State University of Control Systems and Radioelectronics, Tomsk, 634050 (Russian Federation)

    2015-10-27

    The copolymer of the vinyl chloride-maleic anhydride and silver nano- and microparticle (70 wt %) composition is offered as a conductive adhesive for fixing various chips on the dielectric substrate. The wiring volume resistivity is up to 3.1×10{sup −8} Ohm×m. The adhesive strength of the silver-containing polymer composition (70% of Ag) applied under a shear on the dielectric substrate is 106 N/mm{sup 2}. Adhesive layers obtained from these substances have a high thermal conductivity up to λ = 199.93 W/m×K that depends on the amount of Ag in the polymer composition.

  1. Silver-containing polymer composition used in spacecraft and semiconductor optoelectronics control systems

    Science.gov (United States)

    Ivanov, A. A.; Tuev, V. I.

    2015-10-01

    The copolymer of the vinyl chloride-maleic anhydride and silver nano- and microparticle (70 wt %) composition is offered as a conductive adhesive for fixing various chips on the dielectric substrate. The wiring volume resistivity is up to 3.1×10-8 Ohm×m. The adhesive strength of the silver-containing polymer composition (70% of Ag) applied under a shear on the dielectric substrate is 106 N/mm2. Adhesive layers obtained from these substances have a high thermal conductivity up to λ = 199.93 W/m×K that depends on the amount of Ag in the polymer composition.

  2. Influence of gelling additives in the green properties of Al{sub 2}O{sub 3} bodies obtained by aqueous gel casting

    Energy Technology Data Exchange (ETDEWEB)

    Millan, A.J. [IUT, Caracas (Venezuela). Dept. Materiales; Baudin, C.; Moreno, R.; Nieto, M.I. [Consejo Nacional de Investigaciones Cientificas, Madrid (Spain). Ist. de Ceramica y Vidrio

    2002-07-01

    The use of gelling additives, as polysaccharides, in colloidal processing provides adequate mechanical properties to the green bodies to be handled. In this work, Al{sub 2}O{sub 3} gel casting is studied by using agar, agarose and carrageenan as gelling additives. The rheological behaviour of the gel casting slurries on cooling is studied. The green characteristics of the gel cast bodies prepared at different conditions are characterised in terms of density, microstructure and mechanical behaviour (bend strength, elastic modulus) at room temperature. A correlation between the obtained results is established and the best compositions and processing conditions are discussed. (orig.)

  3. Development of rectal delivered thermo-reversible gelling film encapsulating a 5-fluorouracil hydroxypropyl-β-cyclodextrin complex.

    Science.gov (United States)

    Wang, Lu-Lu; Zheng, Wen-Sheng; Chen, Shao-Hua; Han, Yan-Xing; Jiang, Jian-Dong

    2016-02-10

    We have developed a novel 5-Fluorouracil (5FU) formulation for rectal application to improve its therapeutic efficiency in colorectal cancer. The results indicated that 5FU formed an inclusion complex with Hydroxypropyl-β-Cyclodextrin (HP-β-CD). The stoichiometry of the complex was 1:1, with apparent stability constant of 100.4M(-1). After investigating physicochemical properties of the 5FU-HP-β-CD complex encapsulated with thermo-reversible gelling film, the optimized formulation P407/P188/HPMC/5FU-HP-β-CD (18.5/2.5/0.2/15%) was selected and evaluated. The result showed that the 5FU-HP-β-CD complex increased the solubility of 5FU, prolonged and enhanced its releasing. As compared to the raw drug, the transport efficiency of the 5FU-HP-β-CD complex itself or entrapped in thermo-reversible gelling film were respectively 7.3- and 6.8-fold increased, and the cellular uptake of 5-FU 4.9- and 5.4-fold elevated. There was no irritation or damage to rectal sites in the 10h treatment period. Therefore, this HP-β-CD based formulation might improve the therapeutic effect of 5FU on colon-rectal cancer.

  4. Preparation of a Novel Calcium Phosphate Cement Using N-methylene Phosphonic Chitosan as a Gelling Agent

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A modified chitosan ( N-methylene phosphonic Chitosan, NMPC ) was synthesized to improve solubility and ability to bind calcium ion. The properties of the raw material chitosan and its derivative NMPC were characterized using FTIR, 1 H-NMR. The aim of this study was to enhance the compressive CPC by reinforcing with NMPC. A formulation consisting of CPC powder, buffer solution and gelling agent was used for preparation of the CPC. CPC powder consisted of tetracalcium phosphate (TTCP) and dicalcium phosphate anhydrous ( DCPA ). NMPC which acted as the gelling agent was dissolved iuto KH2 PO4 -Na2 HPO4 buffer solution. Each specimen in the mold was sandwiched between two fritted glass sides and kept for 24 hours. Compressive strengths were determined, the setting product was identified using X-ray diffraction and scanning electron microscopy was used to investigate the hydroxyapatite particles size and porosity. The experimental results showed that the dominating influence on the compressive strengths of CPC-NMPC was the HA particle size, its uniformity and appropriate porosity.

  5. Thermoresponsive gelling behavior of concentrated alumina suspensions containing poly(acrylic acid) and PEO-PPO-PEO copolymer.

    Science.gov (United States)

    Kondo, Akira; Xu, Hui; Abe, Hiroya; Naito, Makio

    2012-05-01

    Thermoresponsive gelling behavior of concentrated alumina suspensions with poly(acrylic acid) (PAA) and triblock copolymer (PEO(101)-PPO(56)-PEO(101), Pluronic F127) was investigated as a function of PAA concentration (0.4-1.2 mass%) for ceramic solid free forming. The copolymer species assemble into micelles at temperatures above 15°C, yielding aqueous physical gel. In this study, the concentrated alumina aqueous suspensions (φ=35 vol%) were first prepared using the anionic dispersant of PAA, and then the copolymer species (10 mass%) were dissolved at a cooled temperature at 10°C. The addition of the copolymer species had a negligible influence on the adsorption state of PAA onto the alumina surfaces. The PAA concentration needed for the saturation adsorption on the alumina surfaces was ~0.6 mass%. When the PAA concentration was this value or slightly less, the suspension became gel state at 30°C from low viscous state at 10°C. The thermally induced alumina gel had excellent viscoelastic properties, and thereby the three dimensional periodic ceramic structures were successfully fabricated by a direct colloidal printing method that using the gels as "solid" inks at the room temperature. On the other hand, when it exceeded the saturation adsorption limit, the gelling behavior was not observed, indicating that the non-adsorbing PAA species may partly suppress the micellization of the copolymer on the heating.

  6. A novel in-situ-gelling liquid suppository for site-targeting delivery of anti-colorectal cancer drugs.

    Science.gov (United States)

    Lin, Hong-Ru; Tseng, Chao-Chih; Lin, Yiu-Jiuan; Ling, Ming-Hung

    2012-01-01

    In order to avoid anti-cancer drugs undergoing a first-pass effect and reduce their toxicity, and to solve conventional suppositories defects, we developed an in-situ-gelling and injectable Pluronic-poly(acrylic acid) (Pluronic-PAA) liquid suppository, which could gel fast in the physiological state and had suitable gel strength and bioadhesive force. The liquid suppositories were inserted into the rectum of rabbits without difficulty and leakage, and retained in the rectum for at least 6 h and while releasing the drug. The toxicity and cytotoxic tests indicated that Pluronic and PAA were non-toxic materials and could inhibit colon cancer cells when oxaliplatin was incorporated. C max and AUC0→12h values of oxaliplatin after rectal administration of a oxaliplatin suppository were higher than those for an oxaliplatin solution administered orally. These results suggest that an in-situ-gelling and injectable liquid suppository for humans can be further developed as a more convenient and effective rectal dosage form.

  7. The effect of pressure on phase behaviors of solid polymer electrolyte/salt systems in lithium battery

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Yong Su; Bae, Young Chan [Division of Chemical Engineering and Molecular Thermodynamics Laboratory, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2003-03-01

    A molecular thermodynamic model based on the theory of melting point depression and the modified double lattice model with the free-volume effect is developed to interpret phase behaviors of solid polymer electrolyte (SPE)/salt systems with various pressures. To account for the free-volume effects, we employ the hole-theory proposed by Kleintjens. Quantitative description according to the proposed model is in good agreement with the experimentally observed transition temperatures for given systems. Our results show that eutectic points move toward higher T{sub m} and lower weight fraction region of salt with increasing pressure.

  8. Multilayer systems of alternating chalcogenide As Se and polymer thin films prepared using thermal evaporation and spin-coating techniques

    Science.gov (United States)

    Kohoutek, T.; Wagner, T.; Orava, J.; Krbal, M.; Ilavsky, J.; Vesely, D.; Frumar, M.

    2007-05-01

    We describe preparation and characterization of multilayer planar systems based on alternating chalcogenide As Se and polymer polyamide-imide (PAI) or polyvinyl-butyral (PVB) thin films. We deposited films of thermally evaporated As33Se67 chalcogenide glass periodically alternating with PAI or PVB films. Fifteen layers of As Se+PAI system and 17 layers of As Se+PVB system were deposited. The film thicknesses were approximately 100 nm for all of the film types. Polymer film thicknesses were calculated from profilometric measurements performed by an atomic force microscopy. Optical properties of prepared multilayers and also As Se, PAI and PVB single layers were established using UV vis NIR and ellipsometric spectroscopies. Both, As Se+PAI and As Se+PVB multilayer systems, exhibited the reflection (stop) bands centered near 830 nm. The bandwidth of reflection band of As Se+PAI multilayer was 90 nm while bandwidth of As Se+PVB system increased to 150 nm because PVB films had about 0.2 lower refractive index. A new possibility for the application of chalcogenide thin films appeared as high refractive index materials suitable for fabrication of optical elements (reflectors) for near-infrared region. Changing the films composition and thickness, multilayer systems with tailored position of stop band could be designed and prepared.

  9. Precise Synthesis of Block Polymers Composed of Three or More Blocks by Specially Designed Linking Methodologies in Conjunction with Living Anionic Polymerization System

    Directory of Open Access Journals (Sweden)

    Akira Hirao

    2013-07-01

    Full Text Available This article reviews the successful development of two specially designed linking methodologies in conjunction with a living anionic polymerization system for the synthesis of novel multiblock polymers, composed of three or more blocks, difficult to be synthesized by sequential polymerization. The first methodology with the use of a new heterofunctional linking agent, 2-(4-chloromethylphenylethyldimethylchlorosilane (1, was developed for the synthesis of multiblock polymers containing poly(dimethylsiloxane (PDMS blocks. This methodology is based on the selective reaction of the chain-end silanolate anion of living PDMS, with the silyl chloride function of 1, and subsequent linking reaction of the resulting ω-chain-end-benzyl chloride-functionalized polymer with either a living anionic polymer or living anionic block copolymer. With this methodology, various multiblock polymers containing PDMS blocks, up to the pentablock quintopolymer, were successfully synthesized. The second methodology using an α-phenylacrylate (PA reaction site was developed for the synthesis of multiblock polymers composed of all-vinyl polymer blocks. In this methodology, an α-chain-end-PA-functionalized polymer or block copolymer, via the living anionic polymerization, was first prepared and, then, reacted with appropriate living anionic polymer or block copolymer to link the two polymer chains. As a result, ACB (BCA, BAC (CAB, (ABn, (ACn, ABA, ACA, BCB, and ABCA multiblock polymers, where A, B, and C were polystyrene, poly(2-vinylpyridine, and poly(methyl methacrylate segments, could be successfully synthesized. The synthesis of triblock copolymers, BAB, CAC, and CBC, having molecular asymmetry in both side blocks, was also achieved. Furthermore, the use of living anionic polymers, derived from many other monomers, categorized as either of styrene, 2-vinylpyridine, or methyl methacrylate in monomer reactivity, in the linking methodology enabled the number of

  10. Design and fabrication of polymer based dry adhesives inspired by the gecko adhesive system

    Science.gov (United States)

    Jin, Kejia

    There has been significant interest in developing dry adhesives mimicking the gecko adhesive system, which offers several advantages compared to conventional pressure sensitive adhesives. Specifically, gecko adhesive pads have anisotropic adhesion properties: the adhesive pads (spatulae) stick strongly when sheared in one direction but are non-adherent when sheared in the opposite direction. This anisotropy property is attributed to the complex topography of the array of fine tilted and curved columnar structures (setae) that bear the spatulae. In this thesis, easy, scalable methods, relying on conventional and unconventional techniques are presented to incorporate tilt in the fabrication of synthetic polymer-based dry adhesives mimicking the gecko adhesive system, which provide anisotropic adhesion properties. In the first part of the study, the anisotropic adhesion and friction properties of samples with various tilt angles to test the validity of a nanoscale tape-peeling model of spatular function are measured. Consistent with the Peel Zone model, samples with lower tilt angles yielded larger adhesion forces. Contact mechanics of the synthetic array were highly anisotropic, consistent with the frictional adhesion model and gecko-like. Based on the original design, a new design of gecko-like dry adhesives was developed which showed superior tribological properties and furthermore showed anisotropic adhesive properties without the need for tilt in the structures. These adhesives can be used to reversibly suspend weights from vertical surfaces (e.g., walls) and, for the first time to our knowledge, horizontal surfaces (e.g., ceilings) by simultaneously and judiciously activating anisotropic friction and adhesion forces. Furthermore, adhesion properties between artificial gecko-inspired dry adhesives and rough substrates with varying roughness are studied. The results suggest that both adhesion and friction forces on a rough substrate depends significantly on the

  11. Stable polymer micelle systems as anti-cancer drug delivery carriers

    Science.gov (United States)

    Zeng, Yi

    2005-07-01

    Several temporarily stable polymer micelle systems that might be used as ultrasonic-activated drug delivery carriers were synthesized and investigated. These polymeric micelle systems were PlurogelRTM, Tetronic RTM, poly(ethylene oxide)-b-poly(N-isopropylacrylamide) and poly(ethylene oxide)-b-poly(N-isopropylacrylamide-co-2-hydroxyethyl methacrylate-lactate n). In previous work in our lab, Pruitt et al. developed a stabilized drug carrier named PlurogelRTM [5, 6]. Unfortunately, the rate of the successful PlurogelRTM synthesis was only about 30% by simply following Pruitt's process. In this work, this rate was improved to 60% by combining the process of adding 0.15 M NaCl and/or 10 mul/ml n-butanol and by preheating the solution before polymerization. TetronicsRTM were proved not to be good candidates to form temporarily stable polymeric micelle system by polymerizing interpenetrating networks inside their micelle cores. Tetronic micelle systems treated by this process still were not stable at concentrations below their critical micelle concentration (CMC). Poly(ethylene oxide)-b-poly(N-isopropylacrylamide)-N,N-bis(acryloyl)cystamine micelle-like nanoparticles were developed and characterized. When the N,N-bis(acryloyl)cystamine (BAC) was from 0.2 wt% to 0.75 wt% of the mass of poly(N-isopropylacrylamide), diameters of the nanoparticles at 40°C were less than 150 nm. The cores of the nanoparticles were hydrophobic enough to sequester 1,6-diphenylhexatriene (DPH) and the anti-cancer drug doxorubicin (DOX). Nanoparticles with 0.5 wt% BAC stored at room temperature in 0.002 mg/ml solutions were stable for up to two weeks. Poly(ethylene oxide)-b-poly(N-isopropylacrylamide-co-2-hydroxyethyl methacrylate-lactate n) micelle systems were synthesized and characterized. The degree of polymerization of lactate side group, n, was 3 or 5. The copolymers with N-isopropylacrylamide:2-hydroxyethyl methacrylate-lactate3: poly(ethylene oxide) (NIPAAm:HEMA-lactate 3:PEO) ratios of

  12. Critical interaction strength for surfactant-induced mesomorphic structures in polymer-surfactant systems

    NARCIS (Netherlands)

    Ruokolainen, J.; Torkkeli, M.; Serimaa, R.; Vahvaselka, S.; Saariaho, M.; ten Brinke, G.; Ikkala, O.; Vahvaselkä, Sakari

    1996-01-01

    The critical interaction strength to induce mesomorphic structures in flexible polymers by complexing with surfactants is determined by using surfactants with different hydrogen-bonding strengths;. Two essential requirements have to be satisfied: (i) the association has to be strong enough, otherwis

  13. Molecular Design of Doped Polymers for Thermoelectric Systems-Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Chabinyc, Michael L. [University of California, Santa Barbara; Hawker, Craig J. [University of California, Santa Barbara

    2013-10-09

    The self-assembly of organic semiconducting molecules and polymers is critical for their electrical properties. This project addressed the design of organic semiconductors with novel synthetic building blocks for proton-dopable conducting materials and the molecular order and microstructure of high performance semiconducting polymers blended with charge transfer dopants. Novel azulene donor-acceptor materials were designed and synthesized with unique electronic effects upon protonation to generate charged species in solution. The microstructure and optical properties of these derivatives were examined to develop structure-property relationships. Studies of the microstructure of blends of charge transfer doped semiconducting polymers revealed highly ordered conductive phases in blends. The molecular packing of one blend was studied in detail using a combination of solid-state NMR and x-ray scattering revealing that dopant incorporation is unlikely to be random as assumed in transport models. Studies of the electrical properties of these highly ordered blends revealed a universal trend between the thermopower and electrical conductivity of semiconducting polymers that is independent of the doping mechanism.

  14. Single molecule force spectroscopy of complementary hydrogen-bonded supramolecular systems: dimers, polymers and solvent effects

    NARCIS (Netherlands)

    Embrechts, Anika

    2011-01-01

    The work described in this Thesis aimed at a better understanding of the structure-property relationships of supramolecular assemblies with a specific focus on hydrogen-bond dimers and polymers. The hydrogen-bond strength of (supra)molecular complexes in different solvents is usually determined by m

  15. Hydrophobic polymer monoliths as novel phase separators: Application in continuous liquid-liquid extraction systems

    NARCIS (Netherlands)

    Peroni, D.; Vanhoutte, D.; Vilaplana, F.; Schoenmakers, P.; de Koning, S.; Janssen, H.-G.

    2012-01-01

    Hydrophobic macroporous polymer monoliths are shown to be interesting materials for the construction of "selective solvent gates". With the appropriate surface chemistry and porous properties the monoliths can be made permeable only for apolar organic solvents and not for water. Different poly(butyl

  16. Development of Resonant Soft X-ray Scattering for Polymer Systems at Advanced Light Source

    Science.gov (United States)

    Wang, Cheng; Hexemer, Alexander; Nasiatka, James; Chan, Elaine; Padmore, Howard

    2010-03-01

    It is envisioned that many polymer applications will rely on the heterogeneous morphologies of polymer blends or block copolymers to yield specific functional properties, such as organic light-emitting diodes and photovoltaics. Over the past few years, it has been strongly demonstrated that scattering at soft x-ray energies near the carbon K-edge yields chemically specific and enhanced contrast, thereby enabling structural studies of heterogeneous polymer films with thicknesses of only tens of nanometers. Resonant soft x-ray scattering (RSoXS) will provide the capability for a high-resolution chemical probe with interfacial sensitivity. We will discuss here the development of a dedicated RSoXS setup at the ALS Beamline 11.0.1, which is an elliptically polarized undulator beamline that covers the energy range of 200-1300 eV. It can accommodate a large variety of thin film samples and scattering geometries, including transmission, specular and off-specular reflection, as well as grazing incidence geometries, that will enable users to study both laterally- and depth-resolved structures. The generality, strength, and ease of RSoXS will have significant and immediate impacts in many areas of polymer science and technology. This will be achieved through systematic, collaborative studies of materials with potentially high impact applications.

  17. Synthetic approaches towards new polymer systems by the combination of living carbocationic and anionic polymerizations

    DEFF Research Database (Denmark)

    Feldthusen, Jesper; Ivan, Bela; Muller, Axel. H.E.

    1996-01-01

    to incomplete lithiation of this chain end.In another approach a new functionalization method was developed by end-quenching living polyisobutylene with 1,1-diphenylethylene. After transformation of the groups into 2,2-diphenylvinyl end groups and lithiation polymers were synthesized from protected acrylate...

  18. High rate deposition system for metal-cluster/SiO x C y H z -polymer nanocomposite thin films

    Science.gov (United States)

    Peter, T.; Rehders, S.; Schürmann, U.; Strunskus, T.; Zaporojtchenko, V.; Faupel, F.

    2013-06-01

    A system for deposition of nanocomposite materials consisting of a SiO x C y H z -polymer matrix and Ag nanoclusters is presented. Ag nanoclusters with sizes between 2 and 20 nm are produced in a gas aggregation cluster source and are deposited through a focused beam at a high rate. This cluster source is presented in detail and the characteristics of the produced nanoclusters are shown. Simultaneously, a SiO x C y H z -polymer matrix is grown from the precursor hexamethyldisiloxane in an RF plasma. The beam of clusters is deposited into the growing polymer, forming the composite material. This process allows the rapid deposition of composite material with varying metal nanocluster concentrations and properties. Since the cluster generation is separated from the matrix growth, the properties of both can be controlled independently. In this study, we present two types of nanocomposite samples, in the first the Ag nanoclusters are homogeneously distributed in the matrix, in the second type the Ag nanoclusters form a layer which is covered by the matrix. These samples are investigated using transmission electron micrography to determine the morphology. Furthermore, the optical properties are probed using optical transmission spectroscopy and the plasmonic resonance behavior is discussed.

  19. 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.

  20. In Tube Integrated Electronic Nose System on a Flexible Polymer Substrate

    Directory of Open Access Journals (Sweden)

    Gerhard Tröster

    2012-10-01

    Full Text Available The fabrication of electronic devices, such as gas sensors on flexible polymer substrates, enables the use of electronics in applications where conventional devices on stiff substrates could not be used. We demonstrate the development of a new intra-tube electronic-nose (e-nose gas sensor device with multiple sensors fabricated and integrated on a flexible substrate. For this purpose, we developed a new method of fabricating a sensor array of four gas sensors on a flexible polymer substrate. The method allowed the use of lithography techniques to pattern different polymers with a broad range of solubility parameters. Conductive polymer composites were used as a gas sensitive layer due to the high stretchability of the material. Each of the 30 e-nose devices on one substrate was designed to fit on a polymer strip with a width of 2 mm. A single e-nose strip was successfully integrated into the inlet tube of a gas-measurement apparatus with an inner-tube diameter of 3 mm. Using the e-nose, we were able to differentiate between four different volatile solvent vapors. The tube-integrated e-nose outperformed a chamber-integrated e-nose of the same type in terms of response time and flow-rate influences. The sensor array inside the tube showed a faster response time and detected short pulses of analyte exposure compared to the same sensor array outside of the tube. We measured gas flow rates from 1,000 to 30 sccm without significant changes in sensor performance using this intra-tube e-nose prototype. The tube could be bent to radii < 15 mm with a sensor performance similar to an unbent sensor.

  1. In tube integrated electronic nose system on a flexible polymer substrate.

    Science.gov (United States)

    Kinkeldei, Thomas; Zysset, Christoph; Münzenrieder, Niko; Petti, Luisa; Tröster, Gerhard

    2012-10-12

    The fabrication of electronic devices, such as gas sensors on flexible polymer substrates, enables the use of electronics in applications where conventional devices on stiff substrates could not be used. We demonstrate the development of a new intra-tube electronic-nose (e-nose) gas sensor device with multiple sensors fabricated and integrated on a flexible substrate. For this purpose, we developed a new method of fabricating a sensor array of four gas sensors on a flexible polymer substrate. The method allowed the use of lithography techniques to pattern different polymers with a broad range of solubility parameters. Conductive polymer composites were used as a gas sensitive layer due to the high stretchability of the material. Each of the 30 e-nose devices on one substrate was designed to fit on a polymer strip with a width of 2 mm. A single e-nose strip was successfully integrated into the inlet tube of a gas-measurement apparatus with an inner-tube diameter of 3 mm. Using the e-nose, we were able to differentiate between four different volatile solvent vapors. The tube-integrated e-nose outperformed a chamber-integrated e-nose of the same type in terms of response time and flow-rate influences. The sensor array inside the tube showed a faster response time and detected short pulses of analyte exposure compared to the same sensor array outside of the tube. We measured gas flow rates from 1,000 to 30 sccm without significant changes in sensor performance using this intra-tube e-nose prototype. The tube could be bent to radii sensor performance similar to an unbent sensor.

  2. Polymer dynamics from synthetic polymers to proteins

    Indian Academy of Sciences (India)

    D Richter; R Biehl; M Monkenbush; B Hoffmann; R Merkel

    2008-10-01

    Starting from the standard model of polymer motion - the Rouse model - we briefly present some key experimental results on the mesoscopic dynamics of polymer systems. We touch the role of topological confinement as expressed in the reptation model and discuss in some more detail processes limiting the confinement. In the second part we relate to some new developments concerning the measurement of large-scale internal dynamics of proteins by neutron spin echo.

  3. Three-dimensional dynamic modelling of Polymer-Electrolyte-Membrane-Fuel-Cell-Systems; Dreidimensionale dynamische Modellierung und Berechnung von Polymer-Elektrolyt-Membran-Brennstoffzellen

    Energy Technology Data Exchange (ETDEWEB)

    Vath, Andreas

    2008-12-15

    This thesis deals with dynamic and multi-dimensional modelling of Polymer- Electrolyte-Membrane-Fuel-Cells (PEMFC). The developed models include all the different layers of the fuel cell e.g. flow field, gas diffusion layer, catalyst layer and membrane with their particular physical, chemical and electrical characteristics. The simulation results have been verified by detailed measurements performed at the research centre for hydrogen and solar energy in Ulm (ZSW Ulm). The developed three dimensional model describes the time- and spatial-dependent charge and mass transport in a fuel cell. Additionally, this model allows the analysis of critical operating conditions. For example, the current density distribution for different membranes is shown during insufficient humidification which results in local overstraining and degradation. The model also allows to analyse extreme critical operating conditions, e.g. short time breakdown of the humidification. Furthermore, the model shows the available potential of improvement opportunities in power density and efficiency of PEMFC due to optimisation of the gas diffusion layer, the catalyst and membrane. In the second part of the work the application of PEMFC systems for combined heat and power units is described by one-dimensional models for an electrical power range between 1 kW and 5 kW. This model contains the necessary components, e.g. gas processing, humidification, gas supply, fuel cell stack, heat storage, pumps, auxiliary burner, power inverter und additional aggregates. As a main result, it is possible to distinctly reduce the energy demand and the carbon dioxide exhaust for different load profiles. Today the costs for fuel cell systems are considerably higher than that of the conventional electrical energy supply. (orig.)

  4. Impedance studies of a green blend polymer electrolyte based on PVA and Aloe-vera

    Science.gov (United States)

    Selvalakshmi, S.; Mathavan, T.; Vijaya, N.; Selvasekarapandian, Premalatha, M.; Monisha, S.

    2016-05-01

    The development of polymer electrolyte materials for energy generating and energy storage devices is a challenge today. A new type of blended green electrolyte based on Poly-vinyl alcohol (PVA) and Aloe-vera has been prepared by solution casting technique. The blending of polymers may lead to the increase in stability due to one polymer portraying itself as a mechanical stiffener and the other as a gelled matrix supported by the other. The prepared blend electrolytes were subjected to Ac impedance studies. It has been found out that the polymer film in which 1 gm of PVA was dissolved in 40 ml of Aloe-vera extract exhibits highest conductivity and its value is 3.08 × 10-4 S cm-1.

  5. 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.

  6. FORMULATION AND EVALUATION OF ZIDOVUDINE CONTROLLED RELEASE GAS POWERED SYSTEM USING HYDROPHILLIC POLYMER

    Directory of Open Access Journals (Sweden)

    N. G. Raghavendra Rao

    2011-03-01

    Full Text Available Zidovudine is the first approved compound for the treatment of AIDS; however the main limitation to therapeutic effectiveness of zidovudine is its dose-dependent toxicity, short biological half-life and poor bioavailability. The present research work an attempt has been made to develop the Zidovudine gas powered drug delivery system for controlled release. The Zidovudine gas powered tablets were prepared by direct compression method by using the different grades of hydrophilic polymer like HPMC. The sodium bicarbonates and citric acid were also used as a gas generating agent. The power blend was subjected for pre-compressional parameters. The prepared gas powered tablets are evaluated to post-compressional analysis of parameter such as hardness, friability, weight variation , thickness, drug content, lag time subsequently buoyancy time and in-vitro dissolution studies and swelling index. All the pre and post-compressional parameter are evaluated the results were within acceptable limits. The results of in-vitro buoyancy time and lag time study, the values of in-vitro buoyancy time ranges from 38 to 960 min where as floating lag time ranges from 3.5 to 60 min. The formulation F4 shows the lag time 3.5 min and buoyancy time 960 min. The results of in-vitro buoyancy time and lag time study revealed that as the concentration of sodium bicarbonate increases there is increase in total buoyancy time and decrease in lag time. It is evident from the in-vitro dissolution data that increase in citric acid concentration increased the release rate but reduced the floating time, probably due to of excess carbon dioxide, disturbing the monolithic tablet. The citric acid level in the formulations greatly influenced the drug release. The formulation, F-4 shows maximum drug release at the end of 12 hrs. Form this study, it is concluded that, the formulation retained for longer periods of time in the stomach and provides controlled release of the drug. Hence it

  7. XNBR-grafted halloysite nanotube core-shell as a potential compatibilizer for immiscible polymer systems

    Energy Technology Data Exchange (ETDEWEB)

    Paran, S.M.R.; Naderi, G., E-mail: g.naderi@ippi.ac.ir; Ghoreishy, M.H.R.

    2016-09-30

    Highlights: • Attached an utilitarian silane coupling agent to the HNT via a sol-gel method. • Developed and analyzed the HNT/XNBR core-shell particles via sol-gel technique. • Enhanced the reactivity of the surface of HNT through XNBR grafting. • The act of HNT/XNBR as a compatibilizer in PA6/NBR TPEs. • Immiscible Polymer System with a good balanced physical and mechanical properties. - Abstract: Halloysite nanotubes (HNTs) grafted with carboxylated nitrile byutadiene rubber (XNBR) were synthesized via a sol-gel method. The HNTs as an inorganic cores were pre-treated with 3-Glycidoxypropyl trimethoxysilane, then successfully coated with the XNBR as an organic shell. The properties of XNBR-grafted HNTs were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results suggested that the XNBR grafted to the surfaces of HNTs successfully. Then the TPE nanocomposites based on polyamide-6 (PA6) and nitrile butadiene rubber (NBR) containing various XNBR-grafted and pristine HNTs were prepared via a direct melt mixing method. The morphology, mechanical, dynamic mechanical and rheological properties of the prepared TPE nanocomposites were investigated. The results show that the XNBR-grafted HNTs can effectively improve the morphology and mechanical properties of the PA6/NBR TPEs. The morphology study of the prepared nanocomposites show that the effect of XNBR-grafted HNTs on the size reduction of NBR phase is markedly more effective than the pristine HNTs and rose by 50% in the same concentrations. Mechanical measurements show that the Young’s modulus of the TPE nanocomposites rose by 60% in just 7 wt% of XNBR-grafted HNT loading. The results indicate that the introduction of HNT/XNBR core-shells into the PA6/NBR TPEs can enhances the interfacial interactions

  8. Amphipathic DNA polymers exhibit antiviral activity against systemic Murine Cytomegalovirus infection

    Directory of Open Access Journals (Sweden)

    Juteau Jean-Marc

    2009-12-01

    Full Text Available Abstract Background Phosphorothioated oligonucleotides (PS-ONs have a sequence-independent, broad spectrum antiviral activity as amphipathic polymers (APs and exhibit potent in vitro antiviral activity against a broad spectrum of herpesviruses: HSV-1, HSV-2, HCMV, VZV, EBV, and HHV-6A/B, and in vivo activity in a murine microbiocide model of genital HSV-2 infection. The activity of these agents against animal cytomegalovirus (CMV infections in vitro and in vivo was therefore investigated. Results In vitro, a 40 mer degenerate AP (REP 9 inhibited both murine CMV (MCMV and guinea pig CMV (GPCMV with an IC50 of 0.045 μM and 0.16 μM, respectively, and a 40 mer poly C AP (REP 9C inhibited MCMV with an IC50 of 0.05 μM. Addition of REP 9 to plaque assays during the first two hours of infection inhibited 78% of plaque formation whereas addition of REP 9 after 10 hours of infection did not significantly reduce the number of plaques, indicating that REP 9 antiviral activity against MCMV occurs at early times after infection. In a murine model of CMV infection, systemic treatment for 5 days significantly reduced virus replication in the spleens and livers of infected mice compared to saline-treated control mice. REP 9 and REP 9C were administered intraperitoneally for 5 consecutive days at 10 mg/kg, starting 2 days prior to MCMV infection. Splenomegaly was observed in infected mice treated with REP 9 but not in control mice or in REP 9 treated, uninfected mice, consistent with mild CpG-like activity. When REP 9C (which lacks CpG motifs was compared to REP 9, it exhibited comparable antiviral activity as REP 9 but was not associated with splenomegaly. This suggests that the direct antiviral activity of APs is the predominant therapeutic mechanism in vivo. Moreover, REP 9C, which is acid stable, was effective when administered orally in combination with known permeation enhancers. Conclusion These studies indicate that APs exhibit potent, well tolerated

  9. Polymer-solvent molecular compounds

    CERN Document Server

    Guenet, Jean-Michel

    2010-01-01

    Crystallisable polymers represent a large share of the polymers used for manufacturing a wide variety of objects, and consequently have received continuous attention from scientists these past 60 years. Molecular compounds from crystallisable polymers, particularly from synthetic polymers, are receiving growing interest due to their potential application in the making of new materials such as multiporous membranes capable of capturing large particles as well as small pollutant molecules. The present book gives a detailed description of these promising systems. The first chapter

  10. A polymer-based drug delivery system for the antineoplastic agent bis(maltolato)oxovanadium in mice.

    Science.gov (United States)

    Jackson, J. K.; Min, W.; Cruz, T. F.; Cindric, S.; Arsenault, L.; Von Hoff, D. D.; Degan, D.; Hunter, W. L.; Burt, H. M.

    1997-01-01

    Using vanadyl sulphate, sodium orthovanadate or bis(maltolato)oxovanadium (BMOV), Cruz TF, Morgan A, Min W (1995, Mol Cell Biochem 153: 161-166) have recently demonstrated the antineoplastic effects of vanadium in mice. In this study, the antineoplastic effects of BMOV against human tumour cell lines was confirmed, and this effect was shown to depend on the prolonged exposure of the cells to the drug. We have investigated a polymeric drug delivery system for the sustained delivery of BMOV as an antineoplastic agent in mice. The objective was to design and evaluate an injectable polymer-BMOV paste that would act as a drug implant for the slow but sustained release of BMOV in the mice. In vitro studies showed that the biodegradable polymer poly (Ghlr epsilon epsilon-caprolactone) (PCL) released BMOV in a sustained manner with rates of drug release increasing with increased loading of the drug in the polymer. In vivo studies showed that PCL-BMOV paste implants produced a concentration-dependent inhibition of MDAY-D2 tumour growth via systemic drug delivery. Further in vivo studies showed that 5% BMOV-loaded PCL (containing 20% methoxypolyethylene glycol) was effective in preventing tumour regrowth of resected RIF tumour masses in mice when the PCL-BMOV paste was applied to the resected site for localized drug delivery. The results confirm the potential of vanadium as an antineoplastic agent and show that the injectable PCL-BMOV formulation releases a chemotherapeutic dose of vanadium for the systemic treatment of whole tumours as well as the localized treatment of resected RIF tumours. Images Figure 3 PMID:9083337

  11. 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

  12. Isocyanate-Functionalized Chitin and Chitosan as Gelling Agents of Castor Oil

    Directory of Open Access Journals (Sweden)

    José M. Franco

    2013-06-01

    Full Text Available The main objective of this work was the incorporation of reactive isocyanate groups into chitin and chitosan in order to effectively use the products as reactive thickening agents in castor oil. The resulting gel-like dispersions could be potentially used as biodegradable lubricating greases. Three different NCO–functionalized polymers were obtained: two of them by promoting the reaction of chitosan with 1,6-hexamethylene diisocyanate (HMDI, and the other by using chitin instead of chitosan. These polymers were characterized through 1H-NMR, FTIR and thermogravimetric analysis (TGA. Thermal and rheological behaviours of the oleogels prepared by dispersing these polymers in castor oil were studied by means of TGA and small-amplitude oscillatory shear (SAOS measurements. The evolution and values of the linear viscoelasticity functions with frequency for –NCO–functionalized chitosan- and chitin-based oleogels are quite similar to those found for standard lubricating greases. In relation to long-term stability of these oleogels, no phase separation was observed and the values of viscoelastic functions increase significantly during the first seven days of ageing, and then remain almost constant. TGA analysis showed that the degradation temperature of the resulting oleogels is higher than that found for traditional lubricating greases.

  13. Isocyanate-functionalized chitin and chitosan as gelling agents of castor oil.

    Science.gov (United States)

    Gallego, Rocío; Arteaga, Jesús F; Valencia, Concepción; Franco, José M

    2013-06-03

    The main objective of this work was the incorporation of reactive isocyanate groups into chitin and chitosan in order to effectively use the products as reactive thickening agents in castor oil. The resulting gel-like dispersions could be potentially used as biodegradable lubricating greases. Three different NCO-functionalized polymers were obtained: two of them by promoting the reaction of chitosan with 1,6-hexamethylene diisocyanate (HMDI), and the other by using chitin instead of chitosan. These polymers were characterized through 1H-NMR, FTIR and thermogravimetric analysis (TGA). Thermal and rheological behaviours of the oleogels prepared by dispersing these polymers in castor oil were studied by means of TGA and small-amplitude oscillatory shear (SAOS) measurements. The evolution and values of the linear viscoelasticity functions with frequency for -NCO-functionalized chitosan- and chitin-based oleogels are quite similar to those found for standard lubricating greases. In relation to long-term stability of these oleogels, no phase separation was observed and the values of viscoelastic functions increase significantly during the first seven days of ageing, and then remain almost constant. TGA analysis showed that the degradation temperature of the resulting oleogels is higher than that found for traditional lubricating greases.

  14. Microcontact imprinting of algae for biofuel systems: the effects of the polymer concentration.

    Science.gov (United States)

    Lee, Mei-Hwa; Thomas, James L; Lai, Ming-Yuan; Shih, Ching-Ping; Lin, Hung-Yin

    2014-11-25

    Microcontact imprinting of cells often involves the deposition of a polymer solution onto a monolayer cell stamp, followed by solvent evaporation. Thus, the concentration of the polymer may play an important role in the final morphology and efficacy of the imprinted film. In this work, various concentrations of poly(ethylene-co-vinyl alcohol) (EVAL) were dissolved in dimethyl sulfoxide (DMSO) for the microcontact imprinting of algae on an electrode. Scanning electron microscopy and fluorescence spectrometry were used to characterize the surface morphology and recognition capacity of algae to the algae-imprinted cavities. The readsorption of algae onto algae-imprinted EVAL thin films was quantified to obtain the EVAL concentration that maximized algal binding. Finally, the power and current density of an algal biofuel cell with the algae-imprinted EVAL-coated electrode were measured and found to be approximately double those of such a cell with a Pt/indium tin oxide (ITO)/poly(ethylene terephthalate) (PET) electrode.

  15. Physics in Cell Biology: Actin as a Model System for Polymer Physics

    Science.gov (United States)

    Frey, Erwin

    Living cells are soft bodies of a characteristic form, but endowed with a capacity for a steady turnover of their structures. Both of these material properties, i.e. recovery of the shape after an external stress has been imposed and dynamic structural reorganization, are essential for many cellular phenomena. The structural element responsible for the extraordinary mechanical and dynamical properties of eukaryotic cells is a three-dimensional assembly of protein fibers, the cytoskeleton. These fibers are semiflexible polymers with a stiffness intermediate between rigid rods and freely jointed chains. We discuss the statistical mechanics of individual semiflexible polymers and analyze the viscoelastic properties of solutions and cross linked networks of these biopolymers.

  16. "Thunderstruck": Plasma-Polymer-Coated Porous Silicon Microparticles As a Controlled Drug Delivery System.

    Science.gov (United States)

    McInnes, Steven J P; Michl, Thomas D; Delalat, Bahman; Al-Bataineh, Sameer A; Coad, Bryan R; Vasilev, Krasimir; Griesser, Hans J; Voelcker, Nicolas H

    2016-02-01

    Controlling the release kinetics from a drug carrier is crucial to maintain a drug's therapeutic window. We report the use of biodegradable porous silicon microparticles (pSi MPs) loaded with the anticancer drug camphothecin, followed by a plasma polymer overcoating using a loudspeaker plasma reactor. Homogenous "Teflon-like" coatings were achieved by tumbling the particles by playing AC/DC's song "Thunderstruck". The overcoating resulted in a markedly slower release of the cytotoxic drug, and this effect correlated positively with the plasma polymer coating times, ranging from 2-fold up to more than 100-fold. Ultimately, upon characterizing and verifying pSi MP production, loading, and coating with analytical methods such as time-of-flight secondary ion mass spectrometry, scanning electron microscopy, thermal gravimetry, water contact angle measurements, and fluorescence microscopy, human neuroblastoma cells were challenged with pSi MPs in an in vitro assay, revealing a significant time delay in cell death onset.

  17. Engineered Organometallic Polymer and Hybrid Systems Containing Nanoparticles and/or Poly(ferrocenylsilanes)

    Science.gov (United States)

    Roskov, Kristen Ekiert

    Formation of polymer nanocomposites is becoming an increasingly attractive and facile means by which to combine the desirable properties of metals and metal oxides (e.g., electrical, magnetic, optical, and thermal) with those of polymers (e.g., flexible, lightweight and tough). Incorporation of nanoscale objects such as spheroidal nanoparticles or elongated nanorods into electrospun polymer nano/microfibers measuring from 50 nm to 1 mum in diameter yields functional nanomaterials that can be used in various applications ranging from data storage and conductive nanowires to nonwoven sensors, magnetic filters and drug delivery patches. By aligning nanoscale objects in one-dimensional constructs, we expect that desirable attributes arising from highly anisotropic electronic, optical, thermal, magnetic, and catalytic properties can be realized. The objective of this study is to gain a better fundamental understanding of how to controllably align and position nanoparticles and nanorods within polymer nano/microfibers to generate unique properties. To achieve this objective, we focus on four specific process strategies. In the first, superparamagnetic iron oxide nanoparticles (SPIONs) are aligned into one-dimensional nanoarrays through the use of magnetic field-assisted electrospinning. In this case, an electromagnet is positioned near the Taylor cone of the suspension to be electrospun so that the magnetic field is oriented perpendicular to the electric field. Transmission electron microscopy (TEM) is utilized to ascertain the morphology of the resultant nanocomposite fibers and reveals that the SPION nanoarrays persist intact beyond 1 mum. Since the magnetic field can be pulsed, the length of the nanoarrays can be judiciously controlled. Magnetization hysteresis curves measured on a superconducting quantum interference device yield saturation magnetization and mean magnetic moment values. Secondly, gold nanorods (GNRs) varying in aspect ratio have been flow-aligned in

  18. THE ROTATION BARRIER OF ELECTRON SPIN PROBE IN THE STUDY OF POLYMER SYSTEM

    Institute of Scientific and Technical Information of China (English)

    YU Tongyin; GUO Shiqing; GE Mingtao

    1984-01-01

    In the study of molecular motion of polymer by means of ESR in combination with spin probe,owing to that the ESR spectrum depicts only the behavior of spin probe, the information obtained is of indirect nature. Hence the relationship between them must first be investigated before any conclusion could be drawn. In this paper, two parameters TR and CR are introduced to characterize the changing of tumbling rate of spin probe, and the concept of rotation barrier of spin probe is proposed. It is considered that the magnitude of the rotation barrier is determined by the internal cavity size and distribution in polymer. When the temperature is raised, the size and distribution of the cavities change accordingly, thus the tumbling of spin probe changes gradually from a slower to a higher rate.

  19. 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.

  20. Influence of D/A ratio on photovoltaic performance of a highly efficient polymer solar cell system

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Xia [State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Zhang, Maojie; Zhang, Shaoqing; Huo, Lijun; Hou, Jianhui [State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Tan, Jiahui; Hu, Wenping; Li, Yongfang [Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2012-12-18

    A new copolymer PIDTDTQx based on indacenodithiophene and quinoxaline is synthesized and characterized. The correlation between the D/A ratio, mobility, and photovoltaic properties, as well as morphology of the D/A blend based on a PIDTDTQx:PC{sub 70}BM system is investigated. The power conversion efficiency of the polymer solar cells based on PIDTDTQx/PC{sub 70}BM (1:4, w/w) reaches 7.51%. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Olfaction Presentation System Using Odor Scanner and Odor-Emitting Apparatus Coupled with Chemical Capsules of Alginic Acid Polymer

    Science.gov (United States)

    Sakairi, Minoru; Nishimura, Ayako; Suzuki, Daisuke

    For the purpose of the application of odor to information technology, we have developed an odor-emitting apparatus coupled with chemical capsules made of alginic acid polymer. This apparatus consists of a chemical capsule cartridge including chemical capsules of odor ingredients, valves to control odor emission, and a temperature control unit. Different odors can be easily emitted by using the apparatus. We have developed an integrated system of vision, audio and olfactory information in which odor strength can be controlled coinciding with on-screen moving images based on analytical results from the odor scanner.

  2. Calculation of liquid-liquid phase separation in a ternary system of a polymer in a mixture of a solvent and a nonsolvent

    NARCIS (Netherlands)

    Altena, Frank W.; Smolders, C.A.

    1982-01-01

    A numerical method for the calculation of the binodal of liquid-liquid phase separation in a ternary system is described. The Flory-Huggins theory for three-component systems is used. Binodals are calculated for polymer/solvent/nonsolvent systems which are used in the preparation of asymmetric ultra

  3. Lax-Phillips evolution as an evolution of Gell-Mann-Hartle-Griffiths histories and emergence of the Schr\\"oedinger equation for a stable history

    CERN Document Server

    Bar, D

    2002-01-01

    Using the Gell-Mann-Hartle-Griffiths formalism in the framework of the Flesia-Piron form of the Lax-Phillips theory we show that the Schr\\"oedinger equation may be derived as a condition of stability of histories. This mechanism is realized in a mathematical structure closely related to the Zeno effect.

  4. Visit of the ATLAS cavern by Prof. Murray Gell-Mann, Physics Nobel 1969. With Dr Peter Jenni and Dr Alison Lister

    CERN Multimedia

    Maximilien Brice

    2012-01-01

    Murray Gell-Mann, well known for proposing the quark model and as a recipient of the Nobel Prize in Physics in 1969, came to CERN on 23 January. During his visit he gave a theoretical physics seminar on decoherent histories in quantum mechanics.

  5. Informed Materials Discovery: Designing New Engineering Polymer Systems Using High Throughput Modeling Techniques

    Science.gov (United States)

    2016-10-27

    for equations of state, in: Journal de Physique IV (Proceedings), Vol. 110, EDP sciences , 2003, pp. 809–814. [11] J. P. Foreman, D. Porter, S. Behzadi...The compression yield behaviour of polymethyl methacrylate over a wide range of temperatures and strain-rates, Journal of Materials Science 8 (7...materials science , group interaction modeling, polymers, materials discovery 16.  SECURITY CLASSIFICATION OF: 17.  LIMITATION OF ABSTRACT SAR 18.  NUMBER OF

  6. A predictive group-contribution simplified PC-SAFT equation of state: Application to polymer systems

    DEFF Research Database (Denmark)

    Tihic, Amra; Kontogeorgis, Georgios; von Solms, Nicolas

    2008-01-01

    A group-contribution (GC) method is coupled with the molecular-based perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state (EoS) to predict its characteristic pure compound parameters. The estimation of group contributions for the parameters is based on a parameter...... are the molecular structure of the polymer of interest in terms of functional groups and a single binary interaction parameter for accurate mixture calculations....

  7. PHOTOREFRACTIVE POLYMERS

    NARCIS (Netherlands)

    Morichere, D; Malliaras, G.G; Krasnikov, V.V.; Bolink, H.J; Hadziioannou, G

    1995-01-01

    The use of polymers as photorefractive materials offers many advantages : flexibility in synthesis, doping, processing and low cost. The required functionalities responsible for photorefractivity, namely charge generation, transport, trapping and linear electrooptic effect are given in the polymer w

  8. PHOTOREFRACTIVE POLYMERS

    NARCIS (Netherlands)

    Morichere, D; Malliaras, G.G; Krasnikov, V.V.; Bolink, H.J; Hadziioannou, G

    1995-01-01

    The use of polymers as photorefractive materials offers many advantages : flexibility in synthesis, doping, processing and low cost. The required functionalities responsible for photorefractivity, namely charge generation, transport, trapping and linear electrooptic effect are given in the polymer w

  9. Cationic β-cyclodextrin polymer applied to a dual cyclodextrin polyelectrolyte multilayer system.

    Science.gov (United States)

    Junthip, Jatupol; Tabary, Nicolas; Leclercq, Laurent; Martel, Bernard

    2015-08-01

    A polyelectrolyte multilayer film (PEM) based on cationic and anionic β-cyclodextrin polyelectrolytes was coated onto a textile substrate for future drug delivery purposes. We firstly synthesized a novel cationic β-cyclodextrin polymer (polyEPG-CD) by crosslinking β-cyclodextrin (βCD) with epichlorohydrin (EP) under basic conditions, in the presence of glycidyltrimetrylammonium chloride (GTMAC) as cationizing group. The influence of preparation conditions has been investigated in order to preferably obtain a water soluble fraction whose charge density and molecular weights were optimal for the layer-by-layer (LbL) deposition process. The different cationic cyclodextrin polymers obtained were characterized by FTIR, NMR, colloidal titration, conductimetry, thermogravimetric analysis and size exclusion chromatography. Besides, the counterpart polyelectrolyte was a β-cyclodextrin polymer crosslinked with citric acid, polyCTR-CD, whose synthesis and characterization have been previously reported. Finally we realized the Layer by Layer (LbL) build-up of the PEM coating onto the textile support, using the dip coating method, by alternatively soaking it in cationic polyEPG-CD and anionic polyCTR-CD solutions. This multilayer self-assembly was monitored by SEM, gravimetry and OWLS in function of both polyelectrolytes concentrations and ratios. Solutions parameters such as pH, ionic strenght were also discussed.

  10. Colorimetric biomimetic sensor systems based on molecularly imprinted polymer membranes for highly-selective detection of phenol in environmental samples

    Directory of Open Access Journals (Sweden)

    Sergeyeva T. A.

    2014-05-01

    Full Text Available Aim. Development of an easy-to-use colorimetric sensor system for fast and accurate detection of phenol in envi- ronmental samples. Methods. Technique of molecular imprinting, method of in situ polymerization of molecularly imprinted polymer membranes. Results. The proposed sensor is based on free-standing molecularly imprinted polymer (MIP membranes, synthesized by in situ polymerization, and having in their structure artificial binding sites capable of selective phenol recognition. The quantitative detection of phenol, selectively adsorbed by the MIP membranes, is based on its reaction with 4-aminoantipyrine, which gives a pink-colored product. The intensity of staining of the MIP membrane is proportional to phenol concentration in the analyzed sample. Phenol can be detected within the range 50 nM–10 mM with limit of detection 50 nM, which corresponds to the concentrations that have to be detected in natural and waste waters in accordance with environmental protection standards. Stability of the MIP-membrane-based sensors was assessed during 12 months storage at room temperature. Conclusions. The sensor system provides highly-selective and sensitive detection of phenol in both mo- del and real (drinking, natural, and waste water samples. As compared to traditional methods of phenol detection, the proposed system is characterized by simplicity of operation and can be used in non-laboratory conditions.

  11. Water-absorbent polymer as a carrier for a discrete deposit of antisense oligodeoxynucleotides in the central nervous system.

    Science.gov (United States)

    Bannai, M; Ichikawa, M; Nishimura, F; Nishihara, M; Takahashi, M

    1998-09-01

    One of the problems of introducing antisense oligodeoxynucleotides (ODN) into the central nervous system (CNS) is their rapid disappearance from the target site due to their dispersion and diffusion, which results in poor uptake and/or retention in cells (M. Morris, A.B. Lucion, Antisense oligonucleotides in the study of neuroendocrine systems, J. Neuroendocrinol. 7 (1995) 493-500; S. Ogawa, H.E. Brown, H.J. Okano, D.W. Pfaff, Cellular uptake of intracerebrally administrated oligodeoxynucleotides in mouse brain, Regul. Pept. 59 (1995) 143-149) [2,5]. Recently, we adapted a new method using water-absorbent polymer (WAP; internally cross-linked starch-grafted-polyacrylates) as a carrier for antisense ODN. The polymer forms a hydro-gel after absorbing water which is chemically and biologically inert. In these studies, the polymer (powder-form) is fully swollen by physiological saline containing antisense ODN (0.2 micromol/ml) to make 80-fold volume gel. Hydro-gel (1 microliter) is injected into the target site, and water solutes are assumed to be diffused stoichiometrically into CNS from the surface of the gel. Histological studies indicate that 24 h after the injection, antisense ODN (5'biotinylated-S-oligos of 15 mer) are distributed to within 800 micrometer from the edge of the area where the gel is located and then gradually disappear from this area within days, but still remain within 300-micrometer distance 7 days later. Antisense ODN are effectively incorporated by all the cell types examined, i.e., neurons, astrocytes and microglias, and suppress the synthesis of the target protein. This method can be adapted to slow delivery of antisense ODN and other water soluble substances into the CNS.

  12. Design of highly active binary catalyst systems for CO2/epoxide copolymerization: polymer selectivity, enantioselectivity, and stereochemistry control.

    Science.gov (United States)

    Lu, Xiao-Bing; Shi, Lei; Wang, Yi-Ming; Zhang, Rong; Zhang, Ying-Ju; Peng, Xiao-Jun; Zhang, Zhi-Chao; Li, Bo

    2006-02-01

    Asymmetric, regio- and stereoselective alternating copolymerization of CO(2) and racemic aliphatic epoxides proceeds effectively under mild temperature and pressure by using a binary catalyst system of a chiral tetradentate Schiff base cobalt complex [SalenCo(III)X] as the electrophile in conjunction with an ionic organic ammonium salt or a sterically hindered strong organic base as the nucleophile. The substituent groups on the aromatic rings, chiral diamine backbone, and axial X group of the electrophile, as well as the nucleophilicity, leaving ability, and coordination ability of the nucleophile, all significantly affect the catalyst activity, polymer selectivity, enantioselectivity, and stereochemistry. A bulky chiral cyclohexenediimine backbone complex [SalcyCo(III)X] with an axial X group of poor leaving ability as the electrophile, combined with a bulky nuclephile with poor leaving ability and low coordination ability, is an ideal binary catalyst system for the copolymerization of CO(2) and a racemic aliphatic epoxide to selectively produce polycarbonates with relatively high enantioselectivity, >95% head-to-tail connectivity, and >99% carbonate linkages. A fast copolymerization of CO(2) and epoxides was observed when the concentration of the electrophile or/and the nucleophile was increased, and the number of polycarbonate chains was proportional to the concentration of the nucleophile. Electrospray ionization mass spectrometry, in combination with a kinetic study, showed that the copolymerization involved the coordination activation of the monomer by the electrophile and polymer chain growth predominately occurring in the nucleophile. Both the enantiomorphic site effect resulting from the chiral electrophile and the polymer chain end effect mainly from the bulky nucleophile cooperatively control the stereochemistry of the CO(2)/epoxide copolymerization.

  13. Polymer Brushes

    NARCIS (Netherlands)

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

    2010-01-01

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

  14. Triclosan antimicrobial polymers

    Directory of Open Access Journals (Sweden)

    Richard C. Petersen

    2016-03-01

    Full Text Available Triclosan antimicrobial molecular fluctuating energies of nonbonding electron pairs for the oxygen atom by ether bond rotations are reviewed with conformational computational chemistry analyses. Subsequent understanding of triclosan alternating ether bond rotations is able to help explain several material properties in Polymer Science. Unique bond rotation entanglements between triclosan and the polymer chains increase both the mechanical properties of polymer toughness and strength that are enhanced even better through secondary bonding relationships. Further, polymer blend compatibilization is considered due to similar molecular relationships and polarities. With compatibilization of triclosan in polymers a more uniform stability for nonpolar triclosan in the polymer solid state is retained by the antimicrobial for extremely low release with minimum solubility into aqueous solution. As a result, triclosan is projected for long extended lifetimes as an antimicrobial polymer additive. Further, triclosan rapid alternating ether bond rotations disrupt secondary bonding between chain monomers in the resin state to reduce viscosity and enhance polymer blending. Thus, triclosan is considered for a polymer additive with multiple properties to be an antimicrobial with additional benefits as a nonpolar toughening agent and a hydrophobic wetting agent. The triclosan material relationships with alternating ether bond rotations are described through a complete different form of medium by comparisons with known antimicrobial properties that upset bacterial cell membranes through rapid fluctuating mechanomolecular energies. Also, triclosan bond entanglements with secondary bonding can produce structural defects in weak bacterial lipid membranes requiring pliability that can then interfere with cell division. Regarding applications with polymers, triclosan can be incorporated by mixing into a resin system before cure, melt mixed with thermoplastic polymers

  15. Triclosan antimicrobial polymers

    Science.gov (United States)

    Petersen, Richard C.

    2016-01-01

    Triclosan antimicrobial molecular fluctuating energies of nonbonding electron pairs for the oxygen atom by ether bond rotations are reviewed with conformational computational chemistry analyses. Subsequent understanding of triclosan alternating ether bond rotations is able to help explain several material properties in Polymer Science. Unique bond rotation entanglements between triclosan and the polymer chains increase both the mechanical properties of polymer toughness and strength that are enhanced even better through secondary bonding relationships. Further, polymer blend compatibilization is considered due to similar molecular relationships and polarities. With compatibilization of triclosan in polymers a more uniform stability for nonpolar triclosan in the polymer solid state is retained by the antimicrobial for extremely low release with minimum solubility into aqueous solution. As a result, triclosan is projected for long extended lifetimes as an antimicrobial polymer additive. Further, triclosan rapid alternating ether bond rotations disrupt secondary bonding between chain monomers in the resin state to reduce viscosity and enhance polymer blending. Thus, triclosan is considered for a polymer additive with multiple properties to be an antimicrobial with additional benefits as a nonpolar toughening agent and a hydrophobic wetting agent. The triclosan material relationships with alternating ether bond rotations are described through a complete different form of medium by comparisons with known antimicrobial properties that upset bacterial cell membranes through rapid fluctuating mechanomolecular energies. Also, triclosan bond entanglements with secondary bonding can produce structural defects in weak bacterial lipid membranes requiring pliability that can then interfere with cell division. Regarding applications with polymers, triclosan can be incorporated by mixing into a resin system before cure, melt mixed with thermoplastic polymers that set on cooling

  16. Calculations of influence of electric field on proton magnetic shielding in molecule, by means of Gell-Mann-Feynman theorem

    Energy Technology Data Exchange (ETDEWEB)

    Volodicheva, M.I.; Rebane, T.K.

    1986-01-01

    A method is proposed for calculating the electric-field-linear contribution to the processional magnetic shielding of the nucleus, based on application on the Gell-Mann-Feyman theorem, using the Pade approximant. Calculational formulas have been derived for the first derivatives of the precessional magnetic shielding of the nucleus with respect to the electric field strength, these formulas containing either experimentally determinable characteristics of the molecules or characteristics obtained by interpolation of the observed properties of isoelectronic molecules. No calculations of wavefunctions are required. For hydrogen and hydrogen halide molecules, values have been calculated for the derivatives, with respect to electric field strength, of the precessional sigma/sub H//sup (1)/ prec and total sigma/sub H//sup (1)/ proton magnetic shielding. The results are in good agreement with experimental data.

  17. Restart of circulation of gelled drilling fluids; Estudo do inicio da recirculacao de fluidos de perfuracao gelificados

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Gabriel M. de [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil); Rocha, Leandro L.V. da; Franco, Admilson T.; Negrao, Cezar O.R. [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil). Programa de Pos Graduacao em Engenharia Mecanica e de Materiais; Martins, Andre L. [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES)

    2008-07-01

    This paper describes a mathematical model that simulates the start-up flow of gelled drilling fluids in annular spaces with the purpose to predict pressure peaks at the beginning of the flow. The model comprises the one-dimensional conservation equations of mass and momentum, which are discretized by Finite Volume Method. Fully implicit and up-wind discretization schemes are used and the resultant algebraic equations are solved iteratively by developing a FORTRAN algorithm. The model has the potentiality to be easily adapted to a flow inside a tube. Cases studies are conducted to evaluate the temporal variation of velocity and pressure fields inside both the annular space and a tube. One observed that increasing fluid compressibility or viscosity leads to a reduction of the pressure peaks. (author)

  18. Integration of polystyrene microlenses with both convex and concave profiles in a polymer-based microfluidic system

    KAUST Repository

    Fan, Yiqiang

    2013-12-20

    This paper reports a new technique of fabricating polystyrene microlenses with both convex and concave profiles that are integrated in polymer-based microfluidic system. The polystyrene microlenses, or microlens array, are fabricated using the free-surface thermal compression molding method. The laser fabricated poly(methyl methacrylate) (PMMA) sheet is used as the mold for the thermal compression molding process. With different surface treatment methods of the PMMA mold, microlenses with either convex or concave profiles could be achieved during the thermal molding process. By integrating the microlenses in the microfluidic systems, observing the flow inside the microchannels is easier. This new technique is rapid, low cost, and it does not require cleanroom facilities. Microlenses with both convex and concave profiles can be easily fabricated and integrated in microfluidic system with this technique. © 2013 Springer-Verlag Berlin Heidelberg.

  19. The Workshop on Conductive Polymers: Final Report

    Science.gov (United States)

    1985-10-01

    Reports are made by groups on: polyacetylene, polyphenylene, polyaniline, and related systems; molecular, crystallographic, and defect structures in conducting polymers; heterocyclic polymers; synthesis of new and improved conducting polymers; future applications possibilities for conducting polymers; and challenges for improved understanding of properties. (DLC)

  20. Water Soluble Polymers for Pharmaceutical Applications

    Directory of Open Access Journals (Sweden)

    Veeran Gowda Kadajji

    2011-11-01

    Full Text Available Advances in polymer science have led to the development of novel drug delivery systems. Some polymers are obtained from natural resources and then chemically modified for various applications, while others are chemically synthesized and used. A large number of natural and synthetic polymers are available. In the present paper, only water soluble polymers are described. They have been explained in two categories (1 synthetic and (2 natural. Drug polymer conjugates, block copolymers, hydrogels and other water soluble drug polymer complexes have also been explained. The general properties and applications of different water soluble polymers in the formulation of different dosage forms, novel delivery systems and biomedical applications will be discussed.

  1. A Wearable and Wireless Gas-Sensing System Using Flexible Polymer/Multi-Walled Carbon Nanotube Composite Films

    Directory of Open Access Journals (Sweden)

    Jin-Chern Chiou

    2017-09-01

    Full Text Available In this study, an integrated flexible gas sensor was developed based on a polymer/multi-walled carbon nanotube composite film by using Bluetooth wireless communication/interface technology. Polymer/multi-walled carbon nanotube composite films were deposited over a polyimide flexible substrate for building a gas sensor array by using a drop-casting method. Sensor response was acquired through interdigitated electrodes and multi-channel sensor boards, which were linked to a Bluetooth wireless transceiver. Additionally, a double-spiral-shaped heater was built into the backside of the gas sensor array as a thermostat to protect it from the influence of ambient temperature. Multi-channel sensing responses were read on a display screen via a smartphone application (app. The advantages of this system include light weight, low cost, highly integrated sensors, wireless telecommunication, and real-time functioning. Thus, it is a promising candidate for deployment in a wearable gas-sensing system used to study air pollution.

  2. Development and characterization of an intraocular biodegradable polymer system containing cyclosporine-A for the treatment of posterior uveitis

    Directory of Open Access Journals (Sweden)

    Juliana Barbosa Saliba

    2008-06-01

    Full Text Available The aim of this study was to synthesize and characterize the biodegradable intraocular implants based on poly (D,L-lactide-co-glycolide (PLGA 75:25 with Cyclosporine-A (CyA and to evaluate their in vitro drug delivery profile. Thermal analysis was conducted by using Thermogravimetry (TG and Differential Scanning Calorimetry (DSC. Phase analysis and crystallinity of the polymer-CyA samples were assessed through X ray diffraction (XRD and Fourier transform infrared spectroscopy (FTIR. Finally, microstructure and morphology of the systems were investigated by Scanning Electron Microscopy (SEM. The results showed that CyA was successfully incorporated into PLGA network with drug loading of approximately 31.6%. Also, based on FTIR and thermal analyses (TGA/DSC no significant physical-chemical interaction was detected at the micro-nanoscale level between polymer/drug. SEM micrographs have indicated a uniform drug distribution in PLGA matrix. XRD patterns have showed that the incorporated semi-crystalline structure of CyA has not significantly altered the polymeric mainly amorphous network. In addition, the results have confirmed the chemical and biological drug stability, the drug distribution into the polymeric matrix and the possibility of cyclosporine prolonged delivery system profile.

  3. 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.

  4. Physicochemical characterization and toxicological evaluation of plant-based anionic polymers and their nanoparticulated system for ocular delivery.

    Science.gov (United States)

    Pathak, Deepa; Kumar, Prashant; Kuppusamy, Gowthamarajan; Gupta, Ankur; Kamble, Bhagyashree; Wadhwani, Ashish

    2014-12-01

    The water-soluble fractions of mucilages and gum from the seeds of fenugreek, isphagula and mango bark exudate were isolated, purified and characterized using X-ray diffraction (XRD) spectrometry, Fourier transform infrared spectroscopy (FT-IR), maldi/GC-MS, elemental analysis, 1D ((1)H and (13)C) and 2D (HMQC, COSY) nuclear magnetic resonance spectroscopy (NMR). The fenugreek mucilage was identified to be a galactomannan chain consisting of 4 units of galactose attached to the backbone of 6 mannose units in 1:1.5 ratio. The isphagula mucilage was identified to be an arabinoxylan polysaccharide chain consisting of 4 units of arabinofuranose attached to the backbone of 9 xylopyrannose units in 1:3 ratio. The mango gum showed the presence of amylose, α-arabinofuranosyl and β-galactopyranosyl, respectively. The characterized mucilages and gum were individually formulated into nanoparticulate system using their complementarily charged polymer chitosan. The particles were observed to be spherical in shape in the range of 61.5-90 nm having zetapotential between 31 and 34 mV and PDI of 0.097-0.241. The prepared nanoparticles were observed to be nonirritant and nontoxic in vitro and in vivo upto 2000 μg/ml. Therefore, these mucilages and gum can be the alternatives of anionic polymers for the ocular drug delivery system.

  5. Understanding the ion dynamics and relaxation behavior from impedance spectroscopy of NaI doped Zwitterionic polymer system

    Science.gov (United States)

    Kumar, Manindra; Tiwari, Tuhina; Chauhan, Jagdish Kumar; Srivastava, Neelam

    2014-12-01

    The ion dynamics and relaxation behavior of a novel polymer electrolyte system is studied by presenting impedance spectroscopy data in a different formalism. The prepared system has conductivity of the order of 10-3 Scm-1 at 303 K, and the RH % = 55. Depressed Nyquist plots and broadened M˝ curves (as a function of ω) indicated the distribution of the relaxation time, which is further confirmed by the fractional value of the Kohlrausch-William-Watts (KWW) function (β ˜ 0.75). The hopping and caged movement of the ions are observed in the experimental frequency range (˜MHz), which is confirmed by the conductivity and dielectric representations. The scaling of the conductivity data, with reference to salt concentration and temperature, are successfully observed by fitting the conductivity data exclusively in the Jonscher Power Law (JPL) region. An inverse relation between τcon and σ indicated a strong correlation between the ion and polymer segment motion. An additional high frequency relaxation phenomenon is observed at 50% of the salt concentration, which is correlated with the self-diffusion of the ion and proposed that such phenomenon is observed when ions have multiplet forming tendency.

  6. Rational design of a thermalresponsive-polymer-switchable FRET system for enhancing the temperature sensitivity of upconversion nanophosphors

    Science.gov (United States)

    Xiao, Qingbo; Li, Yanfang; Li, Fujin; Zhang, Mengxin; Zhang, Zhijun; Lin, Hongzhen

    2014-08-01

    Here we propose a thermoresponsive polymer PNIPAM modulated fluorescence resonance energy transfer (FRET) system to enhance the temperature sensitivity of upconversion nanophosphors (UCNPs). By utilizing red/near-infrared dual emitting NaLuF4:Mn2+,Ln3+ (Ln3+ = Yb3+, Er3+, Tm3+) UCNPs as the energy donor and Au nanoparticles as the acceptor, the temperature resolution of the UCNPs is significantly increased from 3.1 °C to 0.9 °C in the physiological temperature range. Conjugating the UCNPs and acceptors into discrete nanocomposites in our samples facilitates reversible regulation of the emission intensity of UCNPs, which thus would extend their application range in biosensing, especially for probing the dynamic changes of local micro-environments in biological tissues. As there are a broad variety of stimuli to which smart polymers can reversibly respond, our experiments are also extendable to various external conditions in local micro-environments, such as pH values, metal ions, glucose, and tissue-specific enzymes.Here we propose a thermoresponsive polymer PNIPAM modulated fluorescence resonance energy transfer (FRET) system to enhance the temperature sensitivity of upconversion nanophosphors (UCNPs). By utilizing red/near-infrared dual emitting NaLuF4:Mn2+,Ln3+ (Ln3+ = Yb3+, Er3+, Tm3+) UCNPs as the energy donor and Au nanoparticles as the acceptor, the temperature resolution of the UCNPs is significantly increased from 3.1 °C to 0.9 °C in the physiological temperature range. Conjugating the UCNPs and acceptors into discrete nanocomposites in our samples facilitates reversible regulation of the emission intensity of UCNPs, which thus would extend their application range in biosensing, especially for probing the dynamic changes of local micro-environments in biological tissues. As there are a broad variety of stimuli to which smart polymers can reversibly respond, our experiments are also extendable to various external conditions in local micro

  7. The effect of phase morphology on the nature of long-lived charges in semiconductor polymer:fullerene systems

    KAUST Repository

    Dou, Fei

    2015-01-01

    In this work, we investigate the effect of phase morphology on the nature of charges in poly(2,5-bis(3-tetradecyl-thiophen-2-yl)thieno[3,2,-b]thiophene) (pBTTT-C16) and phenyl-C61-butyric acid methyl ester (PC61BM) blends over timescales greater than hundreds of microseconds by quasi-steady-state photoinduced absorption spectroscopy. Specifically, we compare an essentially fully intermixed, one-phase system based on a 1 : 1 (by weight) pBTTT-C16 : PC61BM blend, known to form a co-crystal structure, with a two-phase morphology composed of relatively material-pure domains of the neat polymer and neat fullerene. The co-crystal occurs at a composition of up to 50 wt% PC61BM, because pBTTT-C16 is capable of hosting fullerene derivatives such as PC61BM in the cavities between its side chains. In contrast, the predominantly two-phase system can be obtained by manipulating a 1 : 1 polymer : fullerene blend with the assistance of a fatty acid methyl ester (dodecanoic acid methyl ester, Me12) as additive, which hinders co-crystal formation. We find that triplet excitons and polarons are generated in both phase morphologies. However, polarons are generated in the predominantly two-phase system at higher photon energy than for the structure based on the co-crystal phase. By means of a quasi-steady-state solution of a mesoscopic rate model, we demonstrate that the steady-state polaron generation efficiency and recombination rates are higher in the finely intermixed, one-phase system compared to the predominantly phase-pure, two-phase morphology. We suggest that the polarons generated in highly intermixed structures, such as the co-crystal investigated here, are localised polarons while those generated in the phase-separated polymer and fullerene systems are delocalised polarons. We expect this picture to apply generally to other organic-based heterojunctions of complex phase morphologies including donor:acceptor systems that form, for instance, molecularly mixed amorphous solid

  8. Polymer nanoassemblies for cancer treatment and imaging.

    Science.gov (United States)

    Lee, Hyun Jin; Ponta, Andrei; Bae, Younsoo

    2010-12-01

    Amphiphilic polymers represented by block copolymers self-assemble into well-defined nanostructures capable of incorporating therapeutics. Polymer nanoassemblies currently developed for cancer treatment and imaging are reviewed in this article. Particular attention is paid to three representative polymer nanoassemblies: polymer micelles, polymer micellar aggregates and polymer vesicles. Rationales, design and performance of these polymer nanoassemblies are addressed, focusing on increasing the solubility and chemical stability of drugs. Also discussed are polymer nanoassembly formation, the distribution of polymer materials in the human body and applications of polymer nanoassemblies for combined therapy and imaging of cancer. Updates on tumor-targeting approaches, based on preclinical and clinical results are provided, as well as solutions for current issues that drug-delivery systems have, such as in vivo stability, tissue penetration and therapeutic efficacy. These are discussed to provide insights on the future development of more effective polymer nanoassemblies for the delivery of therapeutics in the body.

  9. Novel colloidal system: Magnetite-polymer particles/lyotropic liquid crystal under magnetic field

    Science.gov (United States)

    Mănăilă-Maximean, D.; Cîrtoaje, C.; Dănilă, O.; Donescu, D.

    2017-09-01

    We obtained a new highly ordered colloidal composite using specially manufactured magnetite-polymer nanoparticles and lyotropic liquid crystal. A good compatibility between the components was ensured by the functionalization of the particles during their synthesis. We studied the laser light transmission for the mixtures filled in sandwich-glass cells with homeotropic and planar treatment of the surfaces under external magnetic field. The Fréedericksz transition critical field was estimated, and its' behavior was compared to our new theoretical model based on the Brochard-de Gennes one.

  10. Liquid Crystal Polymer (LCP) based antenna for flexible system on package (SoP) applications

    KAUST Repository

    Marnat, Loic

    2012-06-01

    The design, fabrication and measurement of a bowtie antenna on a flexible Liquid Crystal Polymer (LCP) substrate is reported in this paper. The antenna is fed by a balun transition which helps improve the gain up to 5.1 dB. The antenna performance is analyzed for both planar and curved substrates. The comparison between simulation and measurements shows a good agreement. This structure can either be used to sense the bending of the substrate or use the bending to tilt the beam. © 2012 IEEE.

  11. Effect of casting solvent and polymer on permeability of propranolol hydrochloride through membrane controlled transdermal drug delivery system

    Directory of Open Access Journals (Sweden)

    Murthy T.E.G.K

    2007-01-01

    Full Text Available In the present work, cellulose acetate and ethyl cellulose films were prepared and evaluated as rate controlling membrane for transdermal drug delivery systems. In each case films were prepared using solutions of the polymer in various solvents to evaluate the influence of the solvent used on the mechanical and permeability properties of the films. Acetone-methanol (8:2, chloroform-methanol (8:2, dichloromethane-methanol (8:2 and ethyl acetate-methanol (8:2 were used as solvents in the preparation of cellulose acetate and ethyl cellulose films. Dibutyl phthalate or propylene glycol at a concentration of 40% w/w of the polymer was used as a plasticizer in the preparation films. The method of moulding was found to be giving thin uniform films. The dry films were evaluated for physical appearance, thickness uniformity, folding endurance, water vapour transmission, drug diffusion and permeability coefficient. Both water vapour transmission and Drug diffusion rate followed zero order kinetics. The mechanism of drug release was governed by Peppas model. The diffusion exponent of release profiles (slope has a value of 1.0360-1.3147 (n>1, which indicates non anomalous transport diffusion. The results obtained in the present study thus indicated that the polymers and solvents used in the preparation of films have shown significant influence on the water vapour transmission, drug diffusion and permeability of the films. Area of patches ranging from 1.29- 4.53 cm 2 were found to yield the desired release rate of propranolol hydrochloride. Cellulose acetate films employed with ethyl acetate:methanol in 8:2 ratio as casting solvent yielded low area (1.29 cm 2 of patch with desired release rate.

  12. Influence of 6-Benzyladenine and gelling agent on the reduction of hyperhydricity in Tectona grandis L.

    Directory of Open Access Journals (Sweden)

    Elisa Quiala

    2014-06-01

    Full Text Available Running title: Controlling hyperhydricity in teakInfluencia de la 6-Bencilaminopurina y el agente gelificante en la reducción de la hiperhidricidad en Tectona grandis L. Abstract:  The influence of different factors on shoot proliferation and the occurrence of hyperhydricity in teak (Tectona grandis L. have been studied. Four concentrations of BA (2.22, 4.44, 6.66 and 8.88 µM and a control treatment with 0 BA were examined. Aiming at reducing the costs during commercial propagation by using gelrite in stead of agar, the use of both gelling agent in the proliferation and hyperhydricity was tested. In order to evaluate if hyperhydricity can be reduced by increasing the gelrite concentration in the culture medium, three concentrations (2.0, 2.5 and 3.0 g l-1 were tested in combination with 4.44 µM BA.  The proliferation and occurrence of hyperhydricity during 21 successive subcultures were evaluated. The highest proliferation was achieved in the treatments with 6.66 or 8.88 µM BA. They yielded 5.22 and 5.56 shoots/explant, respectively. But also, the highest percent of hyperhydric shoots was achieved in this treatment. Gelrite resulted in a higher proliferation, but also an almost two times higher hyperhydricity as compared to agar-solidified media. Satisfactory reduction in hyperhydricity (18% was achieved with 3.0 g l-1 gelrite. However, the successive subcultures onto proliferation in this treatment favored hyperhydricity compromising shoot quality and its competence to proliferate. In vitro teak plants were ex vitro rooted and then transferred to greenhouse conditions for acclimatization; ten weeks after transfer they were ready for field plantation.Key words: cytokinin; forestry; micropropagation; morpho-physiological disorder; teakAbbreviations: BA- 6-Benzyladenine, MS- Murashige and Skoog basal medium, IBA- Indole-3-butyric acid, ANA-Naphtalene acetic acidResumen: Se estudió la influencia de diferentes factores en la proliferaci

  13. Approaches in biotechnological applications of natural polymers

    Directory of Open Access Journals (Sweden)

    José A. Teixeira

    2016-08-01

    Full Text Available Natural polymers, such as gums and mucilage, are biocompatible, cheap, easily available and non-toxic materials of native origin. These polymers are increasingly preferred over synthetic materials for industrial applications due to their intrinsic properties, as well as they are considered alternative sources of raw materials since they present characteristics of sustainability, biodegradability and biosafety. As definition, gums and mucilages are polysaccharides or complex carbohydrates consisting of one or more monosaccharides or their derivatives linked in bewildering variety of linkages and structures. Natural gums are considered polysaccharides naturally occurring in varieties of plant seeds and exudates, tree or shrub exudates, seaweed extracts, fungi, bacteria, and animal sources. Water-soluble gums, also known as hydrocolloids, are considered exudates and are pathological products; therefore, they do not form a part of cell wall. On the other hand, mucilages are part of cell and physiological products. It is important to highlight that gums represent the largest amounts of polymer materials derived from plants. Gums have enormously large and broad applications in both food and non-food industries, being commonly used as thickening, binding, emulsifying, suspending, stabilizing agents and matrices for drug release in pharmaceutical and cosmetic industries. In the food industry, their gelling properties and the ability to mold edible films and coatings are extensively studied. The use of gums depends on the intrinsic properties that they provide, often at costs below those of synthetic polymers. For upgrading the value of gums, they are being processed into various forms, including the most recent nanomaterials, for various biotechnological applications. Thus, the main natural polymers including galactomannans, cellulose, chitin, agar, carrageenan, alginate, cashew gum, pectin and starch, in addition to the current researches about them

  14. Laser self-mixing interferometry in VCSELs - an ultra-compact and massproduceable deflection detection system for nanomechanical polymer cantilever sensors

    DEFF Research Database (Denmark)

    Larsson, David; Yvind, Kresten; Hvam, Jørn Märcher;

    2008-01-01

    We have realised an ultra-compact deflection detection system based on laser self-mixing interferometry in a Vertical-Cavity Surface-Emitting Laser (VCSEL). The system can be used together with polymer nanomechanical cantilevers to form chemical sensors capable of detecting less than 1nm deflection....

  15. Optimizing Polymer Infusion Process for Thin Ply Textile Composites with Novel Matrix System

    Directory of Open Access Journals (Sweden)

    Somen K. Bhudolia

    2017-03-01

    Full Text Available For mass production of structural composites, use of different textile patterns, custom preforming, room temperature cure high performance polymers and simplistic manufacturing approaches are desired. Woven fabrics are widely used for infusion processes owing to their high permeability but their localised mechanical performance is affected due to inherent associated crimps. The current investigation deals with manufacturing low-weight textile carbon non-crimp fabrics (NCFs composites with a room temperature cure epoxy and a novel liquid Methyl methacrylate (MMA thermoplastic matrix, Elium®. Vacuum assisted resin infusion (VARI process is chosen as a cost effective manufacturing technique. Process parameters optimisation is required for thin NCFs due to intrinsic resistance it offers to the polymer flow. Cycles of repetitive manufacturing studies were carried out to optimise the NCF-thermoset (TS and NCF with novel reactive thermoplastic (TP resin. It was noticed that the controlled and optimised usage of flow mesh, vacuum level and flow speed during the resin infusion plays a significant part in deciding the final quality of the fabricated composites. The material selections, the challenges met during the manufacturing and the methods to overcome these are deliberated in this paper. An optimal three stage vacuum technique developed to manufacture the TP and TS composites with high fibre volume and lower void content is established and presented.

  16. In situ synthesis of nano clay filled polyethylene using polymer support metallocenes catalyst system

    Energy Technology Data Exchange (ETDEWEB)

    Murthy, Z.V.P.; Parikh, Parimal A., E-mail: zvpm@ched.svnit.ac.in [Sardar Vallabhbhai National Institute of Technology, Gujarat (India). Chemical Engineering Department; Rajesh, Smitha [Sardar Vallabhbhai National Institute of Technology, Gujarat (India). Sardar Vallabhbhai National Institute of Technology. Chemical Engineering Department

    2011-07-01

    In situ ethylene polymerizations were performed using bis(cyclopentadiene)titanium dichloride supported on poly ethersulfone as catalyst. The bis(cyclopentadiene)titanium dichloride supported on poly ethersulfone catalyst activity estimated by ethylene polymerization was 360 kg PE/mol Ti/h. During polymerization the fillers used were montmorillonite nano clays having surface modifications with 35-45 wt % dimethyl dialkyl(14-18)amine (FA) and 25-30 wt % trimethyl stearyl ammonium (FB). These fillers were pretreated with methylaluminoxine (MAO; co catalyst) for better dispersion onto the polymer matrix. The formation of polyethylene within the whole matrix was confirmed by FTIR studies. It was found that the nature of nano filler did not have any remarkable effect on the melting characteristics of the polymer. TGA study indicates that nano clay FB filled polyethylene has higher thermal stability than nano clay FA filled polyethylene. The melting temperature of the obtained polyethylenes was 142 degree C, which corresponds to that synthesized by the polyether sulfone supported catalyst. (author)

  17. Optimizing Polymer Infusion Process for Thin Ply Textile Composites with Novel Matrix System

    Science.gov (United States)

    Bhudolia, Somen K.; Perrotey, Pavel; Joshi, Sunil C.

    2017-01-01

    For mass production of structural composites, use of different textile patterns, custom preforming, room temperature cure high performance polymers and simplistic manufacturing approaches are desired. Woven fabrics are widely used for infusion processes owing to their high permeability but their localised mechanical performance is affected due to inherent associated crimps. The current investigation deals with manufacturing low-weight textile carbon non-crimp fabrics (NCFs) composites with a room temperature cure epoxy and a novel liquid Methyl methacrylate (MMA) thermoplastic matrix, Elium®. Vacuum assisted resin infusion (VARI) process is chosen as a cost effective manufacturing technique. Process parameters optimisation is required for thin NCFs due to intrinsic resistance it offers to the polymer flow. Cycles of repetitive manufacturing studies were carried out to optimise the NCF-thermoset (TS) and NCF with novel reactive thermoplastic (TP) resin. It was noticed that the controlled and optimised usage of flow mesh, vacuum level and flow speed during the resin infusion plays a significant part in deciding the final quality of the fabricated composites. The material selections, the challenges met during the manufacturing and the methods to overcome these are deliberated in this paper. An optimal three stage vacuum technique developed to manufacture the TP and TS composites with high fibre volume and lower void content is established and presented. PMID:28772654

  18. Orientation-enhanced nonlinear optical properties and phase-conjugate reflective system of a novel Azobenzene doped polymer film

    Institute of Scientific and Technical Information of China (English)

    Xie Ru-Sheng; Fan Wen-Bin; Lu Ming; Zhao You-Yuan

    2007-01-01

    This paper reports that the nonlinear refractive index of a novel organic optical storage film doped azodiphenylamine polymer is measured by using the Z-scan technique. The nonlinear refractive index up to 3.7 ×10-6 cm2/W induced by thermo-optical effect is obtained. It indicates that the sample has excellent optical nonlinear properties. The physical mechanism of the great nonlinear optical effect is analysed and the optical conjugate characteristic is also discussed with degenerate four-wave-mixing. The phase conjugate wave diffracted from the formative refractive index grating in the sample is acquired and its equivalent reflectivity reaches about 22%. On this basis,the reflective wave phase-conjugated mirror system was designed, and the image aberration experienced in propagation in the storage experiment is corrected by using the system.

  19. Combination of Polymer Technology and Carbon Nanotube Array for the Development of an Effective Drug Delivery System at Cellular Level

    Directory of Open Access Journals (Sweden)

    Riggio Cristina

    2009-01-01

    Full Text Available Abstract In this article, a carbon nanotube (CNT array-based system combined with a polymer thin film is proposed as an effective drug release device directly at cellular level. The polymeric film embedded in the CNT array is described and characterized in terms of release kinetics, while in vitro assays on PC12 cell line have been performed in order to assess the efficiency and functionality of the entrapped agent (neural growth factor, NGF. PC12 cell differentiation, following incubation on the CNT array embedding the alginate delivery film, demonstrated the effectiveness of the proposed solution. The achieved results indicate that polymeric technology could be efficiently embedded in CNT array acting as drug delivery system at cellular level. The implication of this study opens several perspectives in particular in the field of neurointerfaces, combining several functions into a single platform.

  20. Surface Grafting of Polymers onto Nano-Sized Particles in Solvent-Free Dry-System and in Ionic Liquid

    Institute of Scientific and Technical Information of China (English)

    Norio TSUBOKAWA

    2005-01-01

    @@ 1Introduction We have reported the grafting of various polymers onto the surface of inorganic nano-sized particles, such as silica, titanium oxide, and carbon black[1]. The polymer-grafted nano-sized particles are known to have excellent properties, such as a good dispersibility in solvents and polymer matrices[1,2]. However, scale-up production of polymer-grafted nano-sized particles was hardly achieved, because complicated procedures, such as centrifugation, filtration, and solvent extraction, are needed for the production of polymer-grafted nano-sized particles, and a lot of abolishing solvent comes out.

  1. 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 ...

  2. A rheological study of hydrophobic-surface-active polymer systems structuration; Etude rheologique de la structuration de systemes polymere hydrophobe-tensioactif

    Energy Technology Data Exchange (ETDEWEB)

    Heinrich, E.

    1997-01-29

    This work deals with the study of the rheology and the structuration of hydrophobic polymer and surfactant systems. The used associative polymers are acrylamide/nonyl methacrylate copolymers and the surfactant is nonionic. They are particularly used for hydrocarbons extraction techniques as drilling (drilling fluids) or wells cementation. The studied materials are first characterized by different analytic techniques. This preliminary stage of the work gives a good insight of the physico-chemical parameters of the systems. The effect of surfactant was shown by studying the variation of Newtonian viscosity as a function of surfactant concentration. This yields bell curves, whose maximum determines the critical aggregation concentration (cac). The hydrophobic effect is analysed in different polymer concentration regimes, in quasi-static conditions, and under shear. The study of the dynamic visco-elasticity of semi-dilute solutions allows to observe the effect of the hydrophobic associations on the relaxation time of the chains. The system can be described as a superposition of two networks of junctions: the network of physical entanglements and a second one formed by the hydrophobic links. Phenomena of structuration have been observed at room temperature for surfactant concentrations close to the cac. The increase of viscosity or elastic modulus can be 3 to 4 orders of magnitude. The effect of the temperature on the structure of the systems is studied as well. The rheological characterization of the Sol-Gel transition is developed and the rheological behavior of the solutions in a structured state shows a critical stress for rupture of the structure. Microscopic observations of the birefringence of the solutions display the existence of lamellar vesicles, which leads to the following assumption: the formation of big spherulites create a rigidification of the macromolecular network. (author) 190 refs.

  3. Extraction of natural red colorants from the fermented broth of Penicillium purpurogenum using aqueous two-phase polymer systems.

    Science.gov (United States)

    Santos-Ebinuma, Valéria Carvalho; Lopes, André Moreni; Pessoa, Adalberto; Teixeira, Maria Francisca Simas

    2015-01-01

    Safety concerns related to the increasing and widespread application of synthetic coloring agents have increased the demand for natural colorants. Fungi have been employed in the production of novel and safer colorants. In order to obtain the colorants from fermented broth, suitable extraction systems must be developed. Aqueous two-phase polymer systems (ATPPS) offer a favorable chemical environment and provide a promising alternative for extracting and solubilizing these molecules. The aim of this study was to investigate the partitioning of red colorants from the fermented broth of Penicillium purpurogenum using an ATPPS composed of poly(ethylene glycol) (PEG) and sodium polyacrylate (NaPA). Red colorants partitioned preferentially to the top (PEG-rich phase). In systems composed of PEG 6,000 g/mol/NaPA 8,000 g/mol, optimum colorant partition coefficient (KC ) was obtained in the presence of NaCl 0.1 M (KC  = 10.30) while the PEG 10,000 g/mol/NaPA 8,000 g/mol system in the presence of Na2 SO4 0.5 M showed the highest KC (14.78). For both polymers, the mass balance (%MB) and yield in the PEG phase (%ηTOP ) were close to 100 and 79%, respectively. The protein selectivity in all conditions evaluated ranged from 2.0-3.0, which shows a suitable separation of the red colorants and proteins present in the fermented broth. The results suggest that the partitioning of the red colorants is dependent on both the PEG molecular size and salt type. Furthermore, the results obtained support the potential application of ATPPS as the first step of a purification process to recover colorants from fermented broth of microorganisms.

  4. In vitro-in vivo evaluation of in situ gelling and thermosensitive ketoprofen liquid suppositories.

    Science.gov (United States)

    Ozgüney, Işık; Kardhiqi, Anita; Yıldız, Gülbeyaz; Ertan, Gökhan

    2014-12-01

    The main objective of this study was to investigate the release and pharmacokinetic profiles of ketoprofen (KP) from developed thermosensitive and mucoadhesive liquid suppositories. Thermosensitive liquid suppositories were prepared using KP, poloxamer 407 (P 407), poloxamer 188 (P 188) and various amounts of different mucoadhesive polymers. In vitro release studies was monitored by the USP XXVI paddle method. The results thus obtained were evaluated kinetically and mechanism of release was analyzed. Identification of poloxamer gel localization in vivo was conducted using white male rabbits by adding 1 % methylene blue. For in vivo studies, twenty-four white male rabbits were randomly divided into three groups. The rabbits in each group were administered with liquid suppository F1 [P407/P188/KP (4/20/2.5 %)], F5 [P407/P188/KP/C (4/20/2.5/0.8 %)] or conventional suppository (F-C) into the rectum. The plasma concentration of KP was analyzed by high performance liquid chromatography (HPLC). C max, AUC, MRT and T max were evaluated. The release of KP was variously affected by the mucoadhesive polymers. In vitro release studies showed that Carbopol 934 P(C) has significant effect on release rate among the mucoadhesive polymers. When the formulations were evaluated kinetically, different kinetic models were obtained. Formulation F6 [P407/P188/KP/C (4/20/2.5/1.6 %)] which contains the highest C concentration and very high viscosity, shows a significantly better fit with Higuchi kinetic model. n value of this formulation was also found approximately 0.5. n exponent results of the other formulations showed that KP might be released from the suppositories by non-Fickian diffusion. Identification of poloxamer gel localization in vivo showed that the suppositories remain in the rectum without leakage after administration. With regard to the results of in vivo studies, the AUC6→14 values of KP in liquid suppository containing C are significantly higher than those in

  5. Poly(vinylidene fluoride)-based, co-polymer separator electrolyte membranes for lithium-ion battery systems

    Science.gov (United States)

    Costa, C. M.; Gomez Ribelles, J. L.; Lanceros-Méndez, S.; Appetecchi, G. B.; Scrosati, B.

    2014-01-01

    In the present paper we report and discuss the physicochemical properties of novel electrolyte membranes, based on poly(vinylidenefluoride-co-trifluoroethylene), PVdF-TrFE, and poly(vinylidenefluoride-co-hexafluoropropylene), PVdF-HFP, co-polymer hosts and the PVdF-TrFE/poly(ethylene oxide (PEO) blend as separators for lithium battery systems. The results have shown that the examined separator membranes, particularly those based on the PVdF co-polymers, are able to uptake large liquid amounts leading to high ionic conductivity values. Tests performed on Li/LiFePO4 and Li/Sn-C cells have revealed very good cycling performance even at high current rates and 100% of DOD, approaching the results achieved in liquid electrolytes. A capacity fading lower than 0.002% per cycle was observed. Particularly, the Li/LiFePO4 cathode cells have exhibited excellent rate capability, being still able to deliver at 2C above 89% of the capacity discharged at 0.1C. These results, in conjunction with the about 100% coulombic efficiency, suggest very good electrolyte/electrode compatibility, which results from the high purity and stability of the electrolyte and electrode materials and the cell manufacturing.

  6. The direct link model for polymer rings using topological field theory and the second topological moment in dense systems

    Energy Technology Data Exchange (ETDEWEB)

    Otto, Matthias [Institut fuer Theoretische Physik, Universitaet Goettingen, Goettingen (Germany)

    2001-03-30

    Polymer rings in solution are either permanently entangled or are not. Permanent topological restrictions give rise to additional entropic interactions apart from the ones arising due to mere chain flexibility or excluded volume. Conversely, entangled polymer rings systems may be formed by closing randomly entangled flexible linear chains. The dependence of linking numbers between randomly entangled rings on the chain length, more specifically the second topological moment , i.e. the average squared linking number, may be determined. In this paper, an approach recently discussed in mathematical physics and called Abelian BF theory, is presented which allows one to express the linking constraint in its simplest form, the Gauss integral, in terms of two gauge fields. The model of Brereton and Shah for a single ring entangled with many other surrounding rings is rederived. The latter model is finally used to calculate the second topological moment, in agreement with a recent result by Ferrari, Kleinert, and Lazzizzera obtained using n-component {phi}{sup 4} theory for the limit n{yields}0. (author)

  7. Ultrasonically enhanced delivery and degradation of PAHs in a polymer-liquid partitioning system by a microbial consortium.

    Science.gov (United States)

    Isaza, Pedro A; Daugulis, Andrew J

    2009-09-01

    The current study examined the effects of ultrasonic irradiation on mass transfer and degradation of PAHs, by an enriched consortium, when delivered from polymeric matrices. Rates of release into methanol under sonicated conditions, relative to unmixed cases, for phenanthrene, fluoranthene, pyrene, and benzo[a]pyrene were increased approximately fivefold, when delivered from Desmopan 9370 A (polyurethane). Similar effects were observed in Hytrel and Kraton D4150 K polymers as well as recycled Bridgestone tires. Enhancements were also displayed as shifts to higher release equilibria under sonicated conditions, relative to non-sonicated cases, agreeing with current knowledge in sonochemistry and attributed to cavitation. Ultrasonic effects on microbial activity were also investigated and cell damage was found to be non- permanent with consortium re-growth being observed after sonic deactivation. Finally, the lumped effect of sonication on degradation of phenanthrene delivered from Desmopan was examined under the absence and presence of sonication. Rates of degradation were found to be increased by a factor of four demonstrating the possibility of using ultrasonic irradiation for improved mass transport in solid-liquid systems. Cellular inactivation effects were not evident, and this was attributed to the attenuation of sonic energy arising from the presence of solid polymer materials in the medium. The findings of the study demonstrate that sonication can be used to improve mass transport of poorly soluble compounds in microbial degradations, and alleviate limiting steps of soil remediation processes proposed in previous research.

  8. Mathematical modeling of degradation for bulk-erosive polymers: applications in tissue engineering scaffolds and drug delivery systems.

    Science.gov (United States)

    Chen, Yuhang; Zhou, Shiwei; Li, Qing

    2011-03-01

    The degradation of polymeric biomaterials, which are widely exploited in tissue engineering and drug delivery systems, has drawn significant attention in recent years. This paper aims to develop a mathematical model that combines stochastic hydrolysis and mass transport to simulate the polymeric degradation and erosion process. The hydrolysis reaction is modeled in a discrete fashion by a fundamental stochastic process and an additional autocatalytic effect induced by the local carboxylic acid concentration in terms of the continuous diffusion equation. Illustrative examples of microparticles and tissue scaffolds demonstrate the applicability of the model. It is found that diffusive transport plays a critical role in determining the degradation pathway, whilst autocatalysis makes the degradation size dependent. The modeling results show good agreement with experimental data in the literature, in which the hydrolysis rate, polymer architecture and matrix size actually work together to determine the characteristics of the degradation and erosion processes of bulk-erosive polymer devices. The proposed degradation model exhibits great potential for the design optimization of drug carriers and tissue scaffolds.

  9. The universal trend of the non-exponential Rouse mode relaxation in polymer systems: a theoretical interpretation based on a generalized Langevin equation.

    Science.gov (United States)

    Colmenero, J

    2015-07-28

    We show that the universal behavior of the Rouse-mode relaxation in polymer systems - which has been recently reported from experimental data [S. Arrese-Igor, et al., Phys. Rev. Lett., 2014, 113, 078302] - can be quantitatively explained in the framework of a theoretical approach based on: (i) a generalized Langevin equation formalism and (ii) a memory function which takes into account the coupling between intra-chain dynamics and collective dynamics. This approach opens the way for generalizing the magnitudes probing chain dynamics in polymer systems.

  10. Polymer artificial muscles

    Directory of Open Access Journals (Sweden)

    Tissaphern Mirfakhrai

    2007-04-01

    Full Text Available The various types of natural muscle are incredible material systems that enable the production of large deformations by repetitive molecular motions. Polymer artificial muscle technologies are being developed that produce similar strains and higher stresses using electrostatic forces, electrostriction, ion insertion, and molecular conformational changes. Materials used include elastomers, conducting polymers, ionically conducting polymers, and carbon nanotubes. The mechanisms, performance, and remaining challenges associated with these technologies are described. Initial applications are being developed, but further work by the materials community should help make these technologies applicable in a wide range of devices where muscle-like motion is desirable.

  11. Rheology of Supramolecular Polymers

    DEFF Research Database (Denmark)

    Shabbir, Aamir

    efficient processes or biomedical areas. Design and development of supramolecular polymers using ionic, hydrogen bonding or transition metal complexes with tailored properties requires deep understanding of dynamics both in linear and non-linear deformations. While linear rheology is important to understand......) hydrogen bonding polymers, and (b) ionic bonding polymers (hereafter termed as ionomers). We study linear and non-linear rheology fora model system of entangled pure poly(n-butyl acrylate), PnBA, homopolymer andfour poly(acrylic acid), PnBA-PAA, copolymers with varying AA side groups synthesizedvia...

  12. Long-Term Anti-Corrosion Performance of a Conducting Polymer-Based Coating System for Steels

    Science.gov (United States)

    Pan, Tongyan; Yu, Qifeng

    2016-06-01

    The long-term durability of a two-layer coating system was evaluated by two accelerated corrosion tests, i.e., the ASTM B117 Salt spray test and the ASTM D5894 Cyclic salt fog/UV exposure test, and a series of surface analyses. The coating system was developed for protecting structural steels from corrosion, including a functional primer made of intrinsically conducting polymer (ICP) and a protective topcoat. The standard pull-off test per ASTM D4541 was employed for characterizing the adhesion of the coating systems to substrate, aided by visual examination of the surface deterioration of the samples. The ICP-based systems demonstrated superior long-term anti-corrosion capacity when a polyurethane topcoat is used. The ICP-based primer made of a waterborne epoxy gave poorer anti-corrosion performance than the ICP-based primer made of regular non-waterborne epoxy, which can be attributed to the lower adhesion the waterborne epoxy demonstrated to the substrate surface. The zinc-rich control systems showed good anti-corrosion durability; however, they may produce excessive oxidative products of zinc to cause coating delamination. Based on the test results, the two-layer coating system consisting of an ICP-based primer and a polyurethane topcoat outperforms the conventional zinc-rich coating systems for corrosion protection of steels.

  13. Dynamics of Polaron at Polymer/Polymer Interface

    Institute of Scientific and Technical Information of China (English)

    DI Bing; MENG Yan; AN Zhong; LI You-Cheng

    2008-01-01

    The migration of a polaron at polymer/polymer interface is believed to be of fundamental importance for the transport and light-emitting properties of conjugated polymer-based light emitting diodes.Based on the onedimensional tight-binding Su-Schrieffer-Heeger(SSH)model,we have investigated polaron dynamics in a onedimensional polymer/polymer system by using a nonadiabatic evolution method.In particular,we focus on how a polaron migrates through the conjugated polymer/polymer interface in the presence of external electric field.The results show that the migration of polaron at the interface depends sensitively on the hopping integrals,the potential barrier induced by the energy mismatch,and the strength of applied electric field which increases the polaron kinetic energy.

  14. Responsive Hydrogels from Associative Block Copolymers: Physical Gelling through Polyion Complexation

    Directory of Open Access Journals (Sweden)

    Christine M. Papadakis

    2017-01-01

    Full Text Available The present review article highlights a specific class of responsive polymer-based hydrogels which are formed through association of oppositely charged polyion segments. The underpinning temporary three-dimensional network is constituted of hydrophilic chains (either ionic or neutral physically crosslinked by ion pair formation arising from intermolecular polyionic complexation of oppositely charged repeating units (polyacid/polybase ionic interactions. Two types of hydrogels are presented: (i hydrogels formed by triblock copolymers bearing oppositely charged blocks (block copolyampholytes, forming self-assembled networks; and (ii hydrogels formed by co-assembly of oppositely charged polyelectrolyte segments belonging to different macromolecules (either block copolymers or homopolyelectrolytes. Due to the weak nature of the involved polyions, these hydrogels respond to pH and are sensitive to the presence of salts. Discussing and evaluating their solution, rheological and structural properties in dependence on pH and ionic strength, it comes out that the hydrogel properties are tunable towards potential applications.

  15. Structure-property relationships in carbon nanotube-polymer systems: Influence of noncovalent stabilization techniques

    Science.gov (United States)

    Liu, Lei

    A variety of experiments were carried out to study the dispersion and microstructure of carbon nanotubes in aqueous suspensions and polymer composites with the goal to improve the electrical conductivity of the composites containing nanotubes. Epoxy composites containing covalently and noncovalently functionalized nanotubes were compared in terms of electrical and mechanical behavior. Covalent functionalization of nanotubes is based on chemical attachments of polyethylenimine (PEI) whereas noncovalent functionalization takes place through physical mixing of nanotubes and PEI. The electrical conductivity is reduced in composites containing covalently functionalized nanotubes due to damage of the tube's conjugated surface that reduces intrinsic conductivity. Conversely, the mechanical properties are always better for epoxy composites containing covalently functionalized nanotubes. Clay particles were used as a rigid dispersing aid for nanotubes in aqueous suspensions and epoxy composites. When both nanotubes and clay were introduced into water by sonication, the suspension is stable for weeks, whereas the nanotubes precipitate almost instantly for the suspension without clay. In epoxy composites, nanotubes form separated clusters of aggregation, whereas a continuous three-dimensional nanotube network is achieved when clay is introduced. Electrical conductivity of the epoxy composite is shown to significantly improve with a small addition of clay and the percolation threshold is simultaneously decreased (from 0.05 wt% nanotubes, when there is no clay, to 0.01 wt% when 2 wt% clay is introduced). The addition of clay can also improve the mechanical properties of the composites, especially at higher clay concentration. Weak polyelectrolytes (i.e., pH-responsive polymers) were also studied for their interaction with nanotubes and the electrical properties of the dried composite films. When dispersed by sonication, Nanotubes show pH-dependent dispersion and stability in

  16. Simultaneous separation/enrichment and detection of trace ciprofloxacin and lomefloxacin in food samples using thermosensitive smart polymers aqueous two-phase flotation system combined with HPLC.

    Science.gov (United States)

    Lu, Yang; Chen, Bo; Yu, Miao; Han, Juan; Wang, Yun; Tan, Zhenjiang; Yan, Yongsheng

    2016-11-01

    Smart polymer aqueous two phase flotation system (SPATPF) is a new separation and enrichment technology that integrated the advantages of the three technologies, i.e., aqueous two phase system, smart polymer and flotation sublation. Ethylene oxide and propylene oxide copolymer (EOPO)-(NH4)2SO4 SPATPF is a pretreatment technique, and it is coupled with high-performance liquid chromatography to analyze the trace ciprofloxacin and lomefloxacin in real food samples. The optimized conditions of experiment were determined in the multi-factor experiment by using response surface methodology. The flotation efficiency of lomefloxacin and ciprofloxacin was 94.50% and 98.23% under the optimized conditions. The recycling experimentsshowed that the smart polymer EOPO could use repeatedly, which will reduce the cost in the future application. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Assessment of microcapsule—catalyst particles healing system in high performance fibre reinforced polymer composite

    Science.gov (United States)

    Bolimowski, P. A.; Wass, D. F.; Bond, I. P.

    2016-08-01

    Autonomous self-healing in carbon fibre reinforced polymer (CFRP) is demonstrated using epoxy resin filled microcapsules and a solid-state catalyst. Microcapsules filled with oligomeric epoxy resin (20-450 μm) and particles of Sc(OTf)3 are embedded in an interleave region of a unidirectional CFRP laminate and tested under mode I loading. Double cantilever beam (DCB) test specimens containing variable concentrations of microcapsules and catalyst were prepared, tested and compared to those healed by manual injection with corresponding healing resin formulation. The healing efficiency was evaluated by comparing the maximum peak load recorded on load-displacement curves for pristine and healed specimens. A 44% maximum recovery was observed for specimens containing 10 wt% of solid phase catalyst and 11 wt% of epoxy microcapsules. However, a significant (80%) decrease in initial strain energy release rate (G IC) was observed for specimens with the embedded healing chemistries.

  18. Silicone Polymer Composites for Thermal Protection System: Fiber Reinforcements and Microstructures

    Science.gov (United States)

    2010-01-01

    R1 R3 R2 O Si R1 R2 O Si R1 R2 R3 n Homopolymer n=10,000 R1=R2= methyl , ethyl or vinyl Si R4 R4 HO O Si R5 R5 O Si R6 R6 O H n n=10,000 R4=R5=R6... methyl , ethyl , vinyl or phenyl Copolymer Figure 1. Chemical structures of ‘SM8000’ silicone polymer. 4 Journal of Composite Materials 0(0) A resin...and has been used extensively in our previous studies.29–31,34–37,41–44 The SSRM is a small-scale, liquid-fueled rocket motor burning kerosene oxygen

  19. Biomimetic insulin-imprinted polymer nanoparticles as a potential oral drug delivery system

    Directory of Open Access Journals (Sweden)

    Paul Pijush Kumar

    2017-06-01

    Full Text Available In this study, we investigate molecularly imprinted polymers (MIPs, which form a three-dimensional image of the region at and around the active binding sites of pharmaceutically active insulin or are analogous to b cells bound to insulin. This approach was employed to create a welldefined structure within the nanospace cavities that make up functional monomers by cross-linking. The obtained MIPs exhibited a high adsorption capacity for the target insulin, which showed a significantly higher release of insulin in solution at pH 7.4 than at pH 1.2. In vivo studies on diabetic Wistar rats showed that the fast onset within 2 h is similar to subcutaneous injection with a maximum at 4 h, giving an engaged function responsible for the duration of glucose reduction for up to 24 h. These MIPs, prepared as nanosized material, may open a new horizon for oral insulin delivery.

  20. A Compact Ionic Polymer Metal Composite (IPMC System with Inductive Sensor for Closed Loop Feedback

    Directory of Open Access Journals (Sweden)

    Jiaqi Wang

    2015-05-01

    Full Text Available Ionic polymer metal composite (IPMC, of which a low actuating voltage (<5 V, high power efficiency and biocompatibility makes it a proven candidate for low power devices. However, due to its inherent nonlinear behaviour and time-variance, feedback control, as well as reliable sensing means, are required for accurate operations. This paper presents an IPMC actuator implemented with an inductive sensor to enhance the reliability and compactness of the overall device. A practical, low cost and importantly, compact inductive sensor fabricated on a printed circuit board (PCB is proposed here. Target material selections and coil design considerations are discussed. It is experimentally determined that the inductive sensor has comparable performance to a laser sensor. Based on a proportional-integral-derivative (PID control results the inductive sensor has demonstrated to be an alternative to a laser sensor allowing devices using IPMC actuators to be compact.