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Sample records for suspension polymerization technique

  1. Comparison of techniques for the determination of conversion during suspension polymerization reactions

    Directory of Open Access Journals (Sweden)

    J. C. Santos

    2008-06-01

    Full Text Available The determination of conversion during suspension polymerization reactions is not an easy task due to the heterogeneity of the reaction medium and the tendency of particles to agglomerate rapidly when stirring is stopped. Usually, bulk polymerization in ampoules is employed to study the kinetics of suspension polymerization reactions. In this work, a comparison of different techniques for the determination of conversion during suspension polymerization reactions is presented. Results showed a good agreement between the conversion obtained by gravimetry during styrene suspension polymerization and on-line conversion monitoring data using fiber-optic based Raman Spectroscopy. Nevertheless, the polymerization rate of styrene bulk polymerization carried out in ampoules was higher than the real reaction rate of styrene suspension polymerization due to slightly higher reaction temperatures. Simulation results using the experimental temperature data in a mathematical model confirmed these results.

  2. Schlenk Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar; Zhao, Junpeng; Zhang, Hefeng; Hadjichristidis, Nikolaos; Mays, Jimmy

    2015-01-01

    Anionic polymerization-high vacuum techniques (HVTs) are doubtlessly the most prominent and reliable experimental tools to prepare polymer samples with well-defined and, in many cases, complex macromolecular architectures. Due to the high demands

  3. Stability Prediction of Polymeric Suspensions of some Fluoroquinolones

    OpenAIRE

    Subhashree Sahoo; Chandra Kanti Chakraborti; Pradipta Kumar Behera

    2014-01-01

    Considering the importance of physical stability, zeta potential values, percentage volume of sedimentation and redispersibility of polymeric suspensions of some fluoroquinolones like Ciprofloxacin (Cipro) and Ofloxacin (Oflox) were measured. These formulations were prepared using two grades of Carbopol polymer such as C934 and C940; and Hydroxypropyl methylcellulose (HPMC). Above mentioned values of each suspension was determined by following standard methods. The results of those experiment...

  4. Elastic Modulus at High Frequency of Polymerically Stabilized Suspensions

    NARCIS (Netherlands)

    Nommensen, P.A.; Duits, Michael H.G.; van den Ende, Henricus T.M.; Mellema, J.

    2000-01-01

    The elastic moduli of polymerically stabilized suspensions consisting of colloidal silica particles coated with endgrafted PDMS (Mn = 80 000) in heptane, were measured as a function of concentration. And the elastic modulus at high frequency G'.. was quantitatively described by model calculations

  5. Synthesis and characterization of Supeparamagnetics Microspheres (PMMA via suspension polymerization

    Directory of Open Access Journals (Sweden)

    Paulo Emilio Feuser

    2014-02-01

    Full Text Available Magnetics nanoparticles (NPMs has found many applications in biomedical and technological areas. The objective of this work is the preparation and characterization of PMMA microspheres containing NPMs coated with oleic acid (NPMs-AO. For the preparation of MNPs-AO was used the coprecipitation method in an aqueous medium. For the preparation of the superparamagnetic microspheres used in suspension polymerization technique. The microspheres showed a size distribution particles of approximately 150um and a spherical morphology. From the analysis of gel permeation chromatography (GPC determined the number average molecular weight (Mw of the magnetics microspheres and there was a variation in the Mw depending on the concentration of MNPs-AO in this reaction. To analyze the magnetic properties used the vibrating sample magnetometer (MAV. The microspheres showed superparamagnetic properties and a value of saturation magnetization (Ms of about 8 emu/g MNPs. Therefore you can conclude that it is possible to obtain superparamagnetics microspheres for a particular application, either, biomedical or technological.

  6. On the synthesis of peptide imprinted polymers by a combined suspension-Epitope polymerization method

    International Nuclear Information System (INIS)

    Kotrotsiou, O.; Chaitidou, S.; Kiparissides, C.

    2009-01-01

    In the past, molecularly imprinted polymers (MIPs), prepared by free-radical bulk polymerization, have been used for the selective recognition of small biomolecules (i.e., amino acids and amino acid derivatives). Presently, there is a need for the synthesis of MIPs capable of recognizing larger biomolecules (i.e., peptides and proteins). Moreover, it is highly desirable the production of MIP microparticles with well-defined morphological characteristics (e.g., particle size distribution, porosity, etc.) via particulate polymerization techniques. In the present study, the synthesis of molecularly imprinted microparticles, produced via the suspension and inverse suspension polymerization methods, using the 'epitope approach', is reported. The hydrophobic (i.e., Boc-Trp-Trp-Trp) or hydrophilic (i.e., His-Phe) oligo-peptides were employed as template molecules. The potential of the combined suspension polymerization method with the 'epitope approach' for the production of MIP microparticles is demonstrated, as well as the specificity and selectivity characteristics of the MIP microparticles towards hydrophobic and hydrophilic oligo-peptides. The proposed method appears to be a very promising and efficient technique for separation of proteins.

  7. Suspension polymerization a process for the production of beaded polymer supports and derived ion exchangers

    International Nuclear Information System (INIS)

    Malik, M.A.

    1995-01-01

    Suspension polymerization techniques for production of beaded polymers are discussed with special reference to styrene divinylbenzene copolymers. Methods to control particle size and size distribution of final copolymer beads are given. Mechanism of copolymerization and constituents of aqueous and oil phase are discussed. Mechanism of porous structure formation and control of porosity are also discussed. Chemical conversion of base copolymers into ion exchange resins is also discussed. (author) 16 figs

  8. Schlenk Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar

    2015-09-01

    Anionic polymerization-high vacuum techniques (HVTs) are doubtlessly the most prominent and reliable experimental tools to prepare polymer samples with well-defined and, in many cases, complex macromolecular architectures. Due to the high demands for time and skilled technical personnel, HVTs are currently used in only a few research laboratories worldwide. Instead, most researchers in this filed are attracted to more facile Schlenk techniques. The basic principle of this technique followed in all laboratories is substantially the same, i.e. the use of alternate vacuum and inert gas atmosphere in glass apparatus for the purification/charging of monomer, solvents, additives, and for the manipulation of air-sensitive compounds such as alkyl metal initiators, organometallic or organic catalysts. However, it is executed quite differently in each research group in terms of the structure of Schlenk apparatus (manifolds, connections, purification/storage flasks, reactors, etc.), the use of small supplementary devices (soft tubing, cannulas, stopcocks, etc.) and experimental procedures. The operational methods are partly purpose-oriented while also featured by a high flexibility, which makes it impossible to describe in detail each specific one. In this chapter we will briefly exemplify the application of Schlenk techniques for anionic polymerization by describing the performance of a few experiments from our own work.

  9. High Vacuum Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar; Hadjichristidis, Nikolaos; Mays, Jimmy

    2015-01-01

    Anionic polymerization high vacuum techniques (HVTs) are the most suitable for the preparation of polymer samples with well-defined complex macromolecular architectures. Though HVTs require glassblowing skill for designing and making polymerization

  10. molecular weight control of a batch suspension polymerization reactor

    International Nuclear Information System (INIS)

    Shahrokhi, M.; Fanaei, M. A.

    2002-01-01

    This paper concerns molecular weight control of a batch polymerization reactor where suspension polymerization of methyl methylacrylate (MMA) takes place. For this purpose, a cascade control structure with two control loops has been selected. The slave loop is used for temperature control using on-line temperature measurements, and the master loop controls the average molecular weights based on its estimated values. Two different control algorithms namely proportional-integral (PI) controller and globally linearizing controller (GLC) have been used for temperature control. An estimator, which has the structure of an extended Kalman filter(EKF), is used for estimating monomer conversion and average molecular weights of polymer using reactor temperature measurements. The performance of proposed control algorithm is evaluated through simulation and experimental studies. The results indicate that a constant average molecular weight cannot be achieved in case of strong gel effect. However, the polydispersity of product will be lower in comparison to isothermal operation. It is also shown that in case of mo dek mismatch, the performance of cascade control is superior compared to the case where only reactor temperature is controlled based on desired temperature trajectory obtained through cascade strategy

  11. High Vacuum Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar

    2015-09-01

    Anionic polymerization high vacuum techniques (HVTs) are the most suitable for the preparation of polymer samples with well-defined complex macromolecular architectures. Though HVTs require glassblowing skill for designing and making polymerization reactor, it is the best way to avoid any termination of living polymers during the number of steps for the synthesis of polymers with complex structure. In this chapter, we describe the different polymerization reactors and HVTs for the purification of monomers, solvents, and other reagents for anionic polymerization as well as few model reactions for the synthesis of polymers with simple to complex structure.

  12. IN VITRO ANTIBACTERIAL ACTIVITIES STUDY OF POLYMERIC CIPROFLOXACIN SUSPENSIONS

    OpenAIRE

    Sahoo Subhashree; Chakraborti Chandra Kanti; Behera Pradipta Kumar

    2012-01-01

    To study the in vitro antibacterial activities of mucoadhesive suspensions containing Ciprofloxacin, three different formulations were prepared by using three polymers, such as Hydroxypropyl methylcellulose (HPMC) (S1), Carbapol934 (S2) and Carbapol940 (S3), along with some common ingredients (bases). For the investigation, agar well diffusion method was performed taking Staphylococcus aureus (ATCC 25923), Bacillus subtilis and Escherichia coli (ATCC 25922). Apart from S. aureus, S1 and Cipro...

  13. Polymeric Nanogels Obtained by Radiation Technique

    Energy Technology Data Exchange (ETDEWEB)

    Ulanski, P.; Kadłubowski, A. K.; Olejnik,; Rokita, B.; Wach, R.; Rosiak, J. M. [Institute of Applied Radiation Chemistry, Technical University of Lodz, Lodz (Poland)

    2009-07-01

    Soft nanomaterials - polymeric nanogels and microgels - have made a fast and brilliant career, from an unwanted by-product of polymerization processes to an important and fashionable topic of interdisciplinary research in the fields of polymer chemistry and physics, materials science, pharmacy and medicine. Together with their larger analogues - macroscopic gels, most known in the form of water-swellable hydrogels - they have a broad field of actual and potential applications ranging from filler materials in coating industry to modern biomaterials.

  14. Polymeric Nanogels Obtained by Radiation Technique

    International Nuclear Information System (INIS)

    Ulanski, P.; Kadłubowski, A.K.; Olejnik; Rokita, B.; Wach, R.; Rosiak, J.M.

    2009-01-01

    Soft nanomaterials - polymeric nanogels and microgels - have made a fast and brilliant career, from an unwanted by-product of polymerization processes to an important and fashionable topic of interdisciplinary research in the fields of polymer chemistry and physics, materials science, pharmacy and medicine. Together with their larger analogues - macroscopic gels, most known in the form of water-swellable hydrogels - they have a broad field of actual and potential applications ranging from filler materials in coating industry to modern biomaterials

  15. Development and validation of an HPLC method to quantify camptothecin in polymeric nanocapsule suspensions.

    Science.gov (United States)

    Granada, Andréa; Murakami, Fabio S; Sartori, Tatiane; Lemos-Senna, Elenara; Silva, Marcos A S

    2008-01-01

    A simple, rapid, and sensitive reversed-phase column high-performance liquid chromatographic method was developed and validated to quantify camptothecin (CPT) in polymeric nanocapsule suspensions. The chromatographic separation was performed on a Supelcosil LC-18 column (15 cm x 4.6 mm id, 5 microm) using a mobile phase consisting of methanol-10 mM KH2PO4 (60 + 40, v/v; pH 2.8) at a flow rate of 1.0 mL/min and ultraviolet detection at 254 nm. The calibration graph was linear from 0.5 to 3.0 microg/mL with a correlation coefficient of 0.9979, and the limit of quantitation was 0.35 microg/mL. The assay recovery ranged from 97.3 to 105.0%. The intraday and interday relative standard deviation values were entrapment efficiency and drug content in polymeric nanocapsule suspensions during the early stage of formulation development.

  16. Gamma Radiation-Induced Template Polymerization Technique

    International Nuclear Information System (INIS)

    Siyam, T.

    2005-01-01

    Gamma radiation induced copolymerization of acrylamide sodiumacrylate (AM-AANa) in the presence and absence of the polymer additive was studied at low monomer concentration(1.4M/l). The results showed that the exponents of the dose rate for the polymerization rate was found to be 1.3 and 1.4 in the absence and in the presence of the polymer additive respectively. The molecular weight of the formed polymer increased by addition of the polymer to the system. In the presence of the polymer the comonomers polymerize on the added polymer. In the absence of the added polymer the comonomers polymerize according to the copolymerization process at the initial stage of the copolymerization. While at high conversion the residual comonomers polymerize on the formed macromolecular chains of the produced polymer. These studies showed that the copolymerization in the presence of added polymer is completely template copolymerization while in the absence of the polymer the copolymerization process is only template process with a high conversion

  17. Influence of Surfactant Sorbitan Monolaurate to Suspension Polymerization of Polyacrylic Acid Super absorbent

    International Nuclear Information System (INIS)

    Dewi Sondari; Nuri Astrini; Lik Anah; Agus Haryono

    2008-01-01

    A super absorbent polymer has been prepared by suspension polymerization reaction using acrylic acid, sodium hydroxide, cyclohexane, potassium persulfate as initiator and sorbitan monolaurate as surfactant. The effect of different weight ratio of acrylic acid/sorbitan monolaurate 20/1, 20/2 and 20/3 were investigated based on its swelling properties, chemical structure by using Fourier Transform-Infra Red (FTIR) Spectroscopy and the surface morphology by scanning electron microscopy (SEM). The molecular weight of polyacrylic acid super absorbent was determinate by intrinsic viscosity measurements in 2 M aqueous sodium hydroxide at 25 o C. The study showed sample with weight ratio of acrylic acid/sorbitan monolaurate = 20/2 have best swelling properties. (author)

  18. Chemical resistance of core-shell particles (PS/PMMA polymerized by seeded suspension

    Directory of Open Access Journals (Sweden)

    Luiz Fernando Belchior Ribeiro

    2017-09-01

    Full Text Available Abstract Core-shell particles were produced on seeded suspension polymerization by using polystyrene (PS as polymer core, or seed, and methyl methacrylate (MMA as the shell forming monomer. Two synthesis routes were evaluated by varying the PS seed conversion before MMA addition. The main purpose of this work was to investigate the influence of synthesis routes on the morphology and chemical resistance of the resulting particles. 1H NMR spectroscopy showed that the use of PS seeds with lower conversion led to the formation of higher amount of poly(styrene-co-MMA. The copolymer acted as a compatibilizer, decreasing the interfacial energy between both homopolymers. As a consequence, a larger amount of reduced PMMA cluster were formed, as was revealed by TEM measurements. Samples in this system showed enhanced resistance to cyclohexane attack compared with pure PS, with a PS extraction of only 37% after 54 hours test.

  19. Chemical resistance of core-shell particles (PS/PMMA) polymerized by seeded suspension

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Luiz Fernando Belchior; Machado, Ricardo Antonio Francisco, E-mail: ricardo.machado@ufsc.br [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Departamento de Engenharia de Materiais; Gonçalves, Odinei Hess [Universidade Técnológica Federal do Paraná(UTFPR), Campo Mourão, PR (Brazil); Marangoni, Cintia [Universidade Federal de Santa Catarina (UFSC), Blumenau, SC (Brazil); Motz, Günter [Lehrstuhl Keramische Werkstoffe, Universität Bayreuth (Germany)

    2017-07-01

    Core-shell particles were produced on seeded suspension polymerization by using polystyrene (PS) as polymer core, or seed, and methyl methacrylate (MMA) as the shell forming monomer. Two synthesis routes were evaluated by varying the PS seed conversion before MMA addition. The main purpose of this work was to investigate the influence of synthesis routes on the morphology and chemical resistance of the resulting particles. {sup 1}H NMR spectroscopy showed that the use of PS seeds with lower conversion led to the formation of higher amount of poly(styrene-co-MMA). The copolymer acted as a compatibilizer, decreasing the interfacial energy between both homopolymers. As a consequence, a larger amount of reduced PMMA cluster were formed, as was revealed by TEM measurements. Samples in this system showed enhanced resistance to cyclohexane attack compared with pure PS, with a PS extraction of only 37% after 54 hours test. (author)

  20. Preparation of Macroporous Poly (vinyl alcohol-co-triallyl isocyanurate) Beads Bearing Aminocarboxylic Acid as Functional Groups by Suspension Polymerization

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Macroporous poly (vinyl acetate-co-triallyl isocyanurate) beads were prepared with suspension polymerization method. The copolymer beads were then transformed into poly (vinyl alcohol-co-triallyl isocyanurate) by ester exchange reaction. Aminocarboxylic acids were immobilized on the copolymer beads by the esterification of hydroxyl groups with diethyl-lenetriaminepentaacetic bisanhydride. The weak acid exchange capacities, specific surface areas and mean pore diameters of the resultant resin beads were measured.

  1. Preparation of microspheres for slow release drug by radiation-induced suspension polymerization and their properties

    International Nuclear Information System (INIS)

    Yoshida, Masaru; Asano, Masaharu; Kaetsu, Isao

    1982-01-01

    The polymer microspheres containing drugs as drug delivery system were made by means of suspension-polymerization by radiation at low temperature by using glass-forming monomers which have stable supercooling properties and large polymerizability at low temperature. The particle distribution depended on the kind of monomer. It was found that the entrapping yield of drug in polymer microspheres increased with increasing viscosity of monomer and that the maximum value on the particle size distribution curve was also shifted to large particle diameter side. In the case of trimethylolpropane trimethacrylate monomer (43 cps), TMPT, the entrapping yield of drug reached 74% and the maximum value in particle size distribution curve appeared in the neighborhood of 105 to 210 mu m ranges. On the other hand, those values in neopentyl glycol dimethacrylate monomer (4 cps) were 12% in former and 44 -- 105 mu m in the latter. The release phenomenon of drugs from polymer microspheres was investigated. for example, the cumulative amount of mitomycin C (water soluble drug) released from TMPT polymer microsphere was about 90% after 30-day dissolution, while in the case of water-insoluble drug such as testosterone the amount of release was about 49% after 40-day dissolution. In all cases, the release rate is constant during the experimental period. Therefore, it was concluded that the release of drugs from polymer microspheres obtained in this study is possible over the long periods. (author)

  2. System and technique for ultrasonic characterization of settling suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Greenwood, Margaret S [Richland, WA; Panetta, Paul D [Richland, WA; Bamberger, Judith A [Richland, WA; Pappas, Richard A [Richland, WA

    2006-11-28

    A system for determining properties of settling suspensions includes a settling container, a mixer, and devices for ultrasonic interrogation transverse to the settling direction. A computer system controls operation of the mixer and the interrogation devices and records the response to the interrogating as a function of settling time, which is then used to determine suspension properties. Attenuation versus settling time for dilute suspensions, such as dilute wood pulp suspension, exhibits a peak at different settling times for suspensions having different properties, and the location of this peak is used as one mechanism for characterizing suspensions. Alternatively or in addition, a plurality of ultrasound receivers are arranged at different angles to a common transmitter to receive scattering responses at a variety of angles during particle settling. Angular differences in scattering as a function of settling time are also used to characterize the suspension.

  3. Preparations of spherical polymeric particles from Tanzanian ...

    African Journals Online (AJOL)

    Spherical Polymeric Particles (SPP) have been prepared from Tanzanian Cashew Nut Shell Liquid (CNSL) by suspension polymerization technique involving either step-growth or chain- growth polymerization mechanisms. The sizes of the SPP, which ranged from 0.1 to 2.0 mm were strongly influenced by the amounts of ...

  4. Synthesis and Evaluation of Molecularly Imprinted Polymeric Microspheres for Chloramphenicol by Aqueous Suspension Polymerization as a High Performance Liquid Chromatography Stationary Phase

    International Nuclear Information System (INIS)

    Zhang, Yan; Lei, Jiandu

    2013-01-01

    Molecularly imprinted microsphere for chloramphenicol (CAP) with high adsorption capacity and excellent selectivity is prepared by aqueous suspension polymerization, in which chloramphenicol is used as template molecule and ethyl acetate as porogen. The CAP-imprinted microspheres are used as high performance liquid chromatography (HPLC) stationary phase and packed into stainless steel column (150 mm Χ 4.6 mm i. d.) for selective separation of chloramphenicol. HPLC analysis suggests that chloramphenicol can be distinguished from not only its structural analogs but also other broad-spectrum antibiotic such as erythromycin and tetracycline. In addition, the binding experiments of CAP-imprinted microspheres are carried out in ethanol/water (1:4, V:V), the results indicate that the maximum apparent static binding capacity of molecularly imprinted microspheres is up to 66.64 mg g -1 according to scatchard model

  5. Studies on selected polymeric materials using the photoacoustic spectroscopic technique

    International Nuclear Information System (INIS)

    Singh, Hukum

    2011-01-01

    Polymethylmethacrylate—graft—polybisphenol—A-carbonate (PMMA-G-PC) with 50% grafting is synthesized. The graft co-polymerization of methylmethacrylate (0.036 mol · lit −1 ) onto polybisphenol—A-carbonate (0.5 g) in the presence of a redox couple formed from potassium persulphate (40 mol · lit −1 ) and thio-urea (30 mmol · lit −1 ) in aqueous nitric acid (0.18 M, 100 ml) in air at (45±2) °C for 3.0 h. Condensation of (PMMA-G-PC) with N- [p-(carboxyl phenyl amino acetic acid)] hydrazide (PCPH) affords polybisphenol-A-carbonate-graft-polymethylmethacrylate hydrazide (PCGH). The photoacoustic (PA) spectra of (PCGH) are recorded in a wavelength range from 200 nm to 800 nm at a modulation frequency of 22 Hz, and compared with those of pure polybisphenol-A-carbonate (PC), (PMMA-G-PC) and (PCPH). In the present work, a non-destructive and non-contact analytical method, namely the photoacoustic technique, is successfully implemented for optical and thermal characterization of selected polymeric materials. The indigenous PA spectrometer used in the present study consists of a 300-W xenon arc lamp, a lock-in amplifier, a chopper, a (1/8)-m monochromator controlled by computer and a home-made PA cell. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  6. Suspension tests on a larger scale. Report from the status seminar on magnetic suspension techniques. Testing of the electrodynamic system started

    Energy Technology Data Exchange (ETDEWEB)

    Rogg, D; Muckli, W

    1976-07-01

    A world record speed for electromagnetically suspended vehicles as well as successful suspension tests with forced-circulation cooled superconducting magnets were the outstanding success reports at the fifth status seminar 'Magnetic suspension techniques' on 31st March and 1st April in Bad Kissingen. The research work on magnetic suspension techniques in the railborne long-distance travel is supported by the Federal Ministry of Research and Technology (BMFT) within the frameworke of the programme 'Railway engineering - New technologies'.

  7. Rheological and electrical properties of polymeric nanoparticle solutions and their influence on RBC suspensions

    Czech Academy of Sciences Publication Activity Database

    Antonova, N.; Koseva, N.; Kowalczyk, A.; Říha, Pavel; Ivanov, I.

    2014-01-01

    Roč. 24, č. 3 (2014), s. 35190 ISSN 1430-6395 Institutional support: RVO:67985874 Keywords : nanoparticles and RBC suspensions * poly(acrylic acid) * rheology * electrical conductivity Subject RIV: BK - Fluid Dynamics Impact factor: 1.078, year: 2014 http://www.ar.ethz.ch/TMPPDF/24308140293.696/ApplRheol_24_35190.pdf

  8. [Use of polymeric suspensions as a viral sorbent to detect cattle serum antibodies].

    Science.gov (United States)

    Stanishevskiĭ, Ia M; Lobova, T P; Gritskova, I A; Belousova, R V; Prokopov, N I; Tret'iakova, I V; Tkalia, E E

    2006-01-01

    The paper shows it possible to use stained polymeric microspheres, 1.7 microm in diameter, that contain viruses onto the surface, in the latex agglutination test to detect antibodies to the bovine serum viruses of infective rhinotracheitis, parainfluenza-3, viral diarrhea, respiratory syncytial infection, and adenoviral infection.

  9. Online observation of emulsion polymerization by fluorescence technique

    CERN Document Server

    Rudschuck, S; Fuhrmann, J

    1999-01-01

    An online observation of local polarity via fluorescence spectroscopy was used to study the formation and growth of polymer particles during an emulsifier-free heterogeneous polymerization. The reaction mixture consisted of styrene dispersed in water and the polymerization was initiated by a macro-initiator (hydrolyzed propene-maleic acid copolymer with t-butyl perester groups). Pyrenyl probes were attached to the backbone of the initiator to analyze the heterogeneous reaction. The experimental results allow a clear distinction of different time regions during the heterogeneous polymerization. Information about the heating period, the latex formation, the particle growth and the final stage of the polymerization process (gel point) were obtained. (11 refs).

  10. Velocity and size distribution measurement of suspension droplets using PDPA technique

    Science.gov (United States)

    Amiri, Shahin; Akbarnozari, Ali; Moreau, Christian; Dolatabadi, Ali

    2015-11-01

    The creation of fine and uniform droplets from a bulk of liquid is a vital process in a variety of engineering applications, such as atomization in suspension plasma spray (SPS) in which the submicron coating materials are injected to the plasma gas through the suspension droplets. The size and velocity of these droplets has a great impact on the interaction of the suspension with the gas flow emanating from a plasma torch and can consequently affect the mechanical and chemical properties of the resultant coatings. In the current study, an aqueous suspension of small glass particles (2-8 μm) was atomized by utilizing an effervescent atomizer of 1 mm orifice diameter which involves bubbling gas (air) directly into the liquid stream. The gas to liquid ratio (GLR) was kept constant at 6% throughout this study. The mass concentration of glass particles varied in the range between 0.5 to 5% in order to investigate the effect of suspension viscosity and surface tension on the droplet characteristics, such as velocity and size distributions. These characteristics were simultaneously measured by using a non-intrusive optical technique, Phase Doppler Particle Anemometry (PDPA), which is based on the light signal scattered from the droplets moving in a measurement volume. The velocity and size distribution of suspension droplets were finally compared to those of distilled water under identical conditions. The results showed a different atomization behaviors due to the reduction in surface tension of the suspension spray.

  11. A study of factors affecting properties of AM/AMPS/NVP terpolymeric microspheres prepared by inverse suspension polymerization

    Science.gov (United States)

    Jiang, J. F.; Zhao, Q.; Lin, M. Q.; Wang, Y. F.; Dang, S. M.; Sun, F. F.

    2015-12-01

    Terpolymeric microspheres were synthesized by the inverse suspension polymerization of functional monomers including AMPS, NVP, and AM. The morphology and size of the obtained microspheres were measured by scanning electron microscopy (SEM) and optical microscopy. Furthermore, the swelling performances of the obtained microspheres were measured with alaser particle analyzer (LPA), and the thermal stability of the microspheres obtained was measured by differential thermal analysis (DSC-TG) and high temperature experiments involving microsphere/water dispersion. The results revealed that the extreme value of the microsphere size distribution decreased from 280 μm to 20 μm as the stirring rate increased from 175 rpm to 500 rpm. At temperatures below 25°C, the maximum achieved swelling ratio of the microspheres was 21, and the thermal stability of the terpolymer microspheres was significantly higher than that of the dipolymer microspheres. The terpolymer/water dispersions were kept at 120°C for 19d before any damage was observed.

  12. A plasma polymerization technique to overcome cerebrospinal fluid shunt infections

    Energy Technology Data Exchange (ETDEWEB)

    Coekeliler, D [Plasma Aided Bioengineering and Biotechnology Research Laboratory, Engineering Faculty, Hacettepe University, 06532, Ankara (Turkey); Caner, H [Department of Neurosurgery, School of Medicine, Baskent University, 06610, Ankara (Turkey); Zemek, J [Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, 162 53, Prague, Czech Republic (Czech Republic); Choukourov, A [Department of Macromolecular Physics, Charles University, V Holesovickach 2, 18000 Prague (Czech Republic); Biederman, H [Department of Macromolecular Physics, Charles University, V Holesovickach 2, 18000 Prague (Czech Republic); Mutlu, M [Plasma Aided Bioengineering and Biotechnology Research Laboratory, Engineering Faculty, Hacettepe University, 06532, Ankara (Turkey)

    2007-03-01

    Prosthetic devices, mainly shunts, are frequently used for temporary or permanent drainage of cerebrospinal fluid. The pathogenesis of shunt infection is a very important problem in modern medicine and generally this is characterized by staphylococcal adhesion to the cerebrospinal fluid shunt surfaces. In this paper, the prevention of the attachment of test microorganism Staphylococcus epidermidis on the cerebrospinal fluid shunt surfaces by 2-hydroxyethylmethacrylate (HEMA) precursor modification in the plasma polymerization system, is reported. Different plasma polymerization conditions (RF discharge power 10-20-30 W, exposure time 5-10-15 min) were employed during the surface modification. The surface chemistry and topology of unmodified and modified shunts was characterized by x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Also, static contact angle measurements were performed to state the change of surface hydrophilicity. All samples were tested in vitro with Staphylococcus epidermidis. A plasma-polymerized HEMA film (PP HEMA) was found to be an alternative simple method to decrease the microorganism attachment and create bacterial anti-fouling surfaces. The attachment of the model microorganism Staphylococcus epidermidis on the shunt surface modified by PP HEMA at 20 W and 15 min was reduced 62.3% if compared to the unmodified control surface of the shunt.

  13. Emulsion Polymerization of Etyl Acrylate: The Effect of Surfactant, Initiator Concentration and PolymerizationTechnique on Particle Size Distribution

    Directory of Open Access Journals (Sweden)

    Nitri Arinda

    2009-04-01

    Full Text Available Emulsion polymerization was conducted using ethyl acrylate monomer. Theeffect of sodium lauryl sulfate concentration, ammonium persulfate concentration, the various of polymerizationtechniques and feeding time to the conversion, particle size and its distribution were observed. The purpose of thisresearch is to obtain the optimum condition of ethyl acrylate homopolymer with particle size around 100 nm, to get theparticle size distribution monodisperse and to get solid content value of the experiment closed to its theoretical value.The optimum condition then could be applied in shell polymerization of core-shell polymers. The results of the researchshowed that semicontinuous technique obtained optimum sodium lauryl sulfate concentration at 20 CMC (criticalmicelle concentration and ammonium persulfate concentration is 3%. By using batch technique that the biggestparticle size is 123 nm with conversion 95.8% and monodisperse. The shorter of feeding time the more monomer ofethyl acrylate being polymerized, it is showed by the higher conversion up to 94.4% and the bigger particle size is107.9 nm.

  14. Simple analytical technique for liquid scintillation counting of environmental carbon-14 using gel suspension method

    International Nuclear Information System (INIS)

    Okai, Tomio; Wakabayashi, Genichiro; Nagao, Kenjiro; Matoba, Masaru; Ohura, Hirotaka; Momoshima, Noriyuki; Kawamura, Hidehisa

    2000-01-01

    A simple analytical technique for liquid scintillation counting of environmental 14 C was developed. Commercially available gelling agent, N-lauroyl-L -glutamic -α,γ-dibutylamide, was used for the gel-formation of the samples (gel suspension method) and for the subsequent liquid scintillation counting of 14 C in the form of CaCO 3 . Our procedure for sample preparation is much simpler than that of the conventional methods and requires no special equipment. Self absorption, stability and reproducibility of gel suspension samples were investigated in order to evaluate the characteristics of the gel suspension method for 14 C activity measurement. The self absorption factor is about 70% and slightly decrease as CaCO 3 weight increase. This is considered to be mainly due to the absorption of β-rays and scintillation light by the CaCO 3 sample itself. No change of the counting rate for the gel suspension sample was observed for more than 2 years after the sample preparation. Four samples were used for checking the reproducibility of the sample preparation method. The same values were obtained for the counting rate of 24 C activity within the counting error. No change of the counting rate was observed for the 're-gelated' sample. These results show that the gel suspension method is appropriate for the 14 C activity measurement by the liquid scintillation counting method and useful for a long-term preservation of the sample for repeated measurement. The above analytical technique was applied to actual environmental samples in Fukuoka prefecture, Japan. Results obtained were comparable with those by other researchers and appear to be reasonable. Therefore, the newly developed technique is useful for the routine monitoring of environmental 14 C. (author)

  15. Reliability of capturing foot parameters using digital scanning and the neutral suspension casting technique

    Science.gov (United States)

    2011-01-01

    Background A clinical study was conducted to determine the intra and inter-rater reliability of digital scanning and the neutral suspension casting technique to measure six foot parameters. The neutral suspension casting technique is a commonly utilised method for obtaining a negative impression of the foot prior to orthotic fabrication. Digital scanning offers an alternative to the traditional plaster of Paris techniques. Methods Twenty one healthy participants volunteered to take part in the study. Six casts and six digital scans were obtained from each participant by two raters of differing clinical experience. The foot parameters chosen for investigation were cast length (mm), forefoot width (mm), rearfoot width (mm), medial arch height (mm), lateral arch height (mm) and forefoot to rearfoot alignment (degrees). Intraclass correlation coefficients (ICC) with 95% confidence intervals (CI) were calculated to determine the intra and inter-rater reliability. Measurement error was assessed through the calculation of the standard error of the measurement (SEM) and smallest real difference (SRD). Results ICC values for all foot parameters using digital scanning ranged between 0.81-0.99 for both intra and inter-rater reliability. For neutral suspension casting technique inter-rater reliability values ranged from 0.57-0.99 and intra-rater reliability values ranging from 0.36-0.99 for rater 1 and 0.49-0.99 for rater 2. Conclusions The findings of this study indicate that digital scanning is a reliable technique, irrespective of clinical experience, with reduced measurement variability in all foot parameters investigated when compared to neutral suspension casting. PMID:21375757

  16. The synthesis of poly(vinylphosphonic acid-co-methacrylic acid) microbeads by suspension polymerization and the characterization of their indium adsorption properties

    International Nuclear Information System (INIS)

    Kwak, Noh-Seok; Baek, Youngmin; Hwang, Taek Sung

    2012-01-01

    Highlights: ► Microbeads were synthesized by suspension polymerization based on VPA, MAA and PEGDA. ► The best preparation condition was determined from the yield, water uptake and IEC. ► The adsorption isotherm of indium was fit to the Langmuir and Freundlich models. - Abstract: Poly(vinylphosphonic acid-co-methacrylic acid) microbeads were synthesized by suspension polymerization, and their indium adsorption properties were investigated. The obtained microbeads were characterized by Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). The microbeads were wrinkled spheres, irrespective of the components, and their sizes ranged from 100 to 200 μm. The microbeads were thermally stable up to 260 °C. As the vinylphosphonic acid (VPA) content was increased, the synthetic yields and ion-exchange capacities decreased and the water uptakes increased. The optimum synthetic yield, ion-exchange capacity and water uptake were obtained at a 0.5 mol ratio of VPA. In addition, the maximum adsorption predicted by the Langmuir adsorption isotherm model was greatest at a 0.5 mol ratio of VPA.

  17. The synthesis of poly(vinylphosphonic acid-co-methacrylic acid) microbeads by suspension polymerization and the characterization of their indium adsorption properties

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Noh-Seok; Baek, Youngmin [Department of Applied Chemistry and Biological Engineering, Chungnam National University, 79 Daehangno, Yuseong-gu, Daejeon 305-764 (Korea, Republic of); Hwang, Taek Sung, E-mail: tshwang@cnu.ac.kr [Department of Applied Chemistry and Biological Engineering, Chungnam National University, 79 Daehangno, Yuseong-gu, Daejeon 305-764 (Korea, Republic of)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Microbeads were synthesized by suspension polymerization based on VPA, MAA and PEGDA. Black-Right-Pointing-Pointer The best preparation condition was determined from the yield, water uptake and IEC. Black-Right-Pointing-Pointer The adsorption isotherm of indium was fit to the Langmuir and Freundlich models. - Abstract: Poly(vinylphosphonic acid-co-methacrylic acid) microbeads were synthesized by suspension polymerization, and their indium adsorption properties were investigated. The obtained microbeads were characterized by Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). The microbeads were wrinkled spheres, irrespective of the components, and their sizes ranged from 100 to 200 {mu}m. The microbeads were thermally stable up to 260 Degree-Sign C. As the vinylphosphonic acid (VPA) content was increased, the synthetic yields and ion-exchange capacities decreased and the water uptakes increased. The optimum synthetic yield, ion-exchange capacity and water uptake were obtained at a 0.5 mol ratio of VPA. In addition, the maximum adsorption predicted by the Langmuir adsorption isotherm model was greatest at a 0.5 mol ratio of VPA.

  18. Assessment of the impact strength of the denture base resin polymerized by various processing techniques

    Directory of Open Access Journals (Sweden)

    Rajashree Jadhav

    2013-01-01

    Full Text Available Aim : To measure the impact strength of denture base resins polymerized using short and long curing cycles by water bath, pressure cooker and microwave techniques. Materials and Methods: For impact strength testing, 60 samples were made. The sample dimensions were 60 mm × 12 mm × 3 mm, as standardized by the American Standards for Testing and Materials (ASTM. A digital caliper was used to locate the midpoint of sample. The impact strength was measured in IZOD type of impact tester using CEAST Impact tester. The pendulum struck the sample and it broke. The energy required to break the sample was measured in Joules. Data were analyzed using Student′s " t" test. Results: There was statistically significant difference in the impact strength of denture base resins polymerized by long curing cycle and short curing cycle in each technique, with the long curing processing being the best. Conclusion: The polymerization technique plays an important role in the influence of impact strength in the denture base resin. This research demonstrates that the denture base resin polymerized by microwave processing technique possessed the highest impact strength.

  19. Cotton fabric coated with nano TiO2-acrylate copolymer for photocatalytic self-cleaning by in-situ suspension polymerization

    International Nuclear Information System (INIS)

    Jiang Xue; Tian Xiuzhi; Gu Jian; Huang Dan; Yang Yiqi

    2011-01-01

    Two kinds of nano TiO 2 -polyacrylate hybrid dispersions, TBM-w and TBM-e were synthesized by in-situ suspension polymerization and solution polymerization respectively, in order to fix the nano TiO 2 on fabrics. The photocatalytic self-cleaning fabrics have received much attention in recent years for its water-saving and environment-protection advantages. However, the fixation of the photocatalyst on fabrics is still a key problem that inhibits industrialization of these eco-friendly fabrics. The cotton fabric was treated by the two hybrid dispersions. The photocatalytic self-cleaning property was characterized. Infrared spectroscopy, burning loss test and thermogravimetry showed that some copolymer chains entangled with the nano TiO 2 . Transmission electron microscope illustrated that there was a polymeric layer on the surface of nano TiO 2 . The average diameter of TBM-w was smaller than that of TBM-e based on size analysis. The photocatalytic decoloration of the grape syrup indicated that the fabric with TiO 2 -polymer hybrid had excellent self-cleaning property.

  20. Analysis of polymeric phenolics in red wines using different techniques combined with gel permeation chromatography fractionation.

    Science.gov (United States)

    Guadalupe, Zenaida; Soldevilla, Alberto; Sáenz-Navajas, María-Pilar; Ayestarán, Belén

    2006-04-21

    A multiple-step analytical method was developed to improve the analysis of polymeric phenolics in red wines. With a common initial step based on the fractionation of wine phenolics by gel permeation chromatography (GPC), different analytical techniques were used: high-performance liquid chromatography-diode array detection (HPLC-DAD), HPLC-mass spectrometry (MS), capillary zone electrophoresis (CZE) and spectrophotometry. This method proved to be valid for analyzing different families of phenolic compounds, such as monomeric phenolics and their derivatives, polymeric pigments and proanthocyanidins. The analytical characteristics of fractionation by GPC were studied and the method was fully validated, yielding satisfactory statistical results. GPC fractionation substantially improved the analysis of polymeric pigments by CZE, in terms of response, repeatability and reproducibility. It also represented an improvement in the traditional vanillin assay used for proanthocyanidin (PA) quantification. Astringent proanthocyanidins were also analyzed using a simple combined method that allowed these compounds, for which only general indexes were available, to be quantified.

  1. Fabrication of Polymeric Coatings with Controlled Microtopographies Using an Electrospraying Technique.

    Directory of Open Access Journals (Sweden)

    Qiongyu Guo

    Full Text Available Surface topography of medical implants provides an important biophysical cue on guiding cellular functions at the cell-implant interface. However, few techniques are available to produce polymeric coatings with controlled microtopographies onto surgical implants, especially onto implant devices of small dimension and with complex structures such as drug-eluting stents. Therefore, the main objective of this study was to develop a new strategy to fabricate polymeric coatings using an electrospraying technique based on the uniqueness of this technique in that it can be used to produce a mist of charged droplets with a precise control of their shape and dimension. We hypothesized that this technique would allow facile manipulation of coating morphology by controlling the shape and dimension of electrosprayed droplets. More specifically, we employed the electrospraying technique to coat a layer of biodegradable polyurethane with tailored microtopographies onto commercial coronary stents. The topography of such stent coatings was modulated by controlling the ratio of round to stretched droplets or the ratio of round to crumped droplets under high electric field before deposition. The shape of electrosprayed droplets was governed by the stability of these charged droplets right after ejection or during their flight in the air. Using the electrospraying technique, we achieved conformal polymeric coatings with tailored microtopographies onto conductive surgical implants. The approach offers potential for controlling the surface topography of surgical implant devices to modulate their integration with surrounding tissues.

  2. Inhaled corticosteroid metered-dose inhalers: how do variations in technique for solutions versus suspensions affect drug distribution?

    Science.gov (United States)

    Robinson, Christie A; Tsourounis, Candy

    2013-03-01

    To assess the literature that evaluates how variations in metered-dose inhaler (MDI) technique affect lung distribution for inhaled corticosteroids (ICSs) formulated as MDI suspensions and solutions. PubMed (up to November 2012) and Cochrane Library (up to November 2012) were searched using the terms metered-dose inhalers, HFA 134a, Asthma/*drug therapy, and inhaled corticosteroids. In addition, reference citations from publications identified were reviewed. All articles in English from the data sources that assessed MDI technique comparing total lung distribution (TLD) of MDI solutions or suspensions formulated with ICSs were included in the review. Five relevant studies were identified. Five controlled studies compared how variations in MDI technique affect TLD for ICS MDI solutions with suspensions. MDI solutions resulted in greater TLD compared with larger particle MDI suspensions. Delayed or early inspiration upon device actuation of MDI solutions resulted in less TLD than coordinated actuation, but with a 3- to 4-times greater TLD than MDI suspensions inhaled using a standard technique. A sixth study evaluated inspiratory flow rates (IFR) for small, medium, and large particles. Rapid and slow IFRs resulted in similar TLD for small particles, while far fewer particles reached the airways with medium and large particles at rapid, rather than slow, IFRs. Based on the literature evaluated, standard MDI technique should be used for ICS suspensions. ICS MDI solutions can provide a higher average TLD than larger-particle ICS suspensions using standard technique, discoordinated inspiration and medication actuation timing, or rapid and slow IFRs. ICS MDI solutions allow for a more forgiving technique, which makes them uniquely suitable options for patients with asthma who have difficultly with MDI technique.

  3. Technique of radiation polymerization in fine art conservation: a potentially new method of restoration and preservation

    International Nuclear Information System (INIS)

    Garnett, J.L.; Major, G.

    1982-01-01

    The technique of using radiation polymerization for the restoration and preservation of art treasures is considered. The processes discussed include both radiation grafting and rapid cure procedures, particularly reactions initiated by uv and eb. Representative examples where the technique has already been used are treated including typical applications with paintings, tapestries, leather and archival repair. The structure of the monomers and oligomers used in both grafting and rapid cure systems is outlined. The experimental conditions where grafting may occur during radiation rapid cure processing are discussed. Possible future developments of the technique are outlined. 1 figure, 8 tables

  4. Coating of calcia-doped ceria with amorphous silica shell by seeded polymerization technique

    International Nuclear Information System (INIS)

    El-Toni, Ahmed Mohamed; Yin, Shu; Yabe, Shinryo; Sato, Tsugio

    2005-01-01

    Calcia-doped ceria is of potential interest as an ultraviolet (UV) radiation blocking material in personal care products. However, its high catalytic ability for oxidation of organic materials makes it difficult to use as a sunscreen material. Therefore, calcia-doped ceria was coated with amorphous silica by means of seeded polymerization technique in order to depress its oxidation catalytic ability. The catalytic ability as well as UV-shielding ability was investigated for coated particles

  5. Preparation of high surface area and high conductivity polyaniline nanoparticles using chemical oxidation polymerization technique

    Science.gov (United States)

    Budi, S.; Yusmaniar; Juliana, A.; Cahyana, U.; Purwanto, A.; Imaduddin, A.; Handoko, E.

    2018-03-01

    In this work, polyaniline nanoparticles were synthesized using a chemical oxidation polymerization technique. The ammonium peroxydisulfate (APS)/aniline ratio, APS dropping time, and polymerization temperature were optimized to increase the surface area and conductivity of the polyaniline.The Fourier-transform infrared (FTIR) spectrum confirmed the formation of emeraldine salt polyaniline. X-ray diffraction (XRD) patterns indicated that amorphous and crystalline phases of the polyaniline were formed with crystallinity less than 40%. Scanning electron microscope (SEM) micrographs showed that the finest nanoparticles with uniform size distribution were obtained at the polymerization temperature of 0°C. A surface area analyzer (SAA) showed that the highest Brunauer-Emmett-Teller surface area (SBET ) of 42.14 m2/gwas obtained from an APS/aniline ratio of 0.75 with a dropping time of 0 s at a polymerization temperature of 0°C. A four-point probe measurement conducted at 75–300K indicated relatively high conductivity of the semiconductor characteristic of the polyaniline.

  6. Characteristics of low polymerization shrinkage flowable resin composites in newly-developed cavity base materials for bulk filling technique.

    Science.gov (United States)

    Nitta, Keiko; Nomoto, Rie; Tsubota, Yuji; Tsuchikawa, Masuji; Hayakawa, Tohru

    2017-11-29

    The purpose of this study was to evaluate polymerization shrinkage and other physical properties of newly-developed cavity base materials for bulk filling technique, with the brand name BULK BASE (BBS). Polymerization shrinkage was measured according to ISO/FDIS 17304. BBS showed the significantly lowest polymerization shrinkage and significantly higher depth of cure than conventional flowable resin composites (p<0.05). The Knoop hardness, flexural strength and elastic modulus of that were significantly lower than conventional flowable resin composites (p<0.05). BBS had the significantly greatest filler content (p<0.05). SEM images of the surface showed failure of fillers. The lowest polymerization shrinkage was due to the incorporation of a new type of low shrinkage monomer, which has urethane moieties. There were no clear correlations between inorganic filler contents and polymerization shrinkage, flexural strength and elastic modulus. In conclusion, the low polymerization shrinkage of BBS will be useful for cavity treatment in dental clinics.

  7. Outcomes of laryngohyoid suspension techniques in an ovine model of profound oropharyngeal dysphagia.

    Science.gov (United States)

    Johnson, Christopher M; Venkatesan, Naren N; Siddiqui, M Tausif; Cates, Daniel J; Kuhn, Maggie A; Postma, Gregory M; Belafsky, Peter C

    2017-12-01

    To evaluate the efficacy of various techniques of laryngohyoid suspension in the elimination of aspiration utilizing a cadaveric ovine model of profound oropharyngeal dysphagia. Animal study. The head and neck of a Dorper cross ewe was placed in the lateral fluoroscopic view. Five conditions were tested: baseline, thyroid cartilage to hyoid approximation (THA), thyroid cartilage to hyoid to mandible (laryngohyoid) suspension (LHS), LHS with cricopharyngeus muscle myotomy (LHS-CPM), and cricopharyngeus muscle myotomy (CPM) alone. Five 20-mL trials of barium sulfate were delivered into the oropharynx under fluoroscopy for each condition. Outcome measures included the penetration aspiration scale (PAS) and the National Institutes of Health (NIH) Swallow Safety Scale (NIH-SSS). Median baseline PAS and NIH-SSS scores were 8 and 6, respectively, indicating severe impairment. THA scores were not improved from baseline. LHS alone reduced the PAS to 1 (P = .025) and NIH-SSS to 2 (P = .025) from baseline. LHS-CPM reduced the PAS to 1 (P = .025) and NIH-SSS to 0 (P = .025) from baseline. CPM alone did not improve scores. LHS-CPM displayed improved NIH-SSS over LHS alone (P = .003). This cadaveric model represents end-stage profound oropharyngeal dysphagia such as what could result from severe neurological insult. CPM alone failed to improve fluoroscopic outcomes in this model. Thyrohyoid approximation also failed to improve outcomes. LHS significantly improved both PAS and NIH-SSS. The addition of CPM to LHS resulted in improvement over suspension alone. NA. Laryngoscope, 127:E422-E427, 2017. © 2017 The American Laryngological, Rhinological and Otological Society, Inc.

  8. Effect of temperature on hydration kinetics and polymerization of tricalcium silicate in stirred suspensions of CaO-saturated solutions

    International Nuclear Information System (INIS)

    Grant, Steven A.; Boitnott, Ginger E.; Korhonen, Charles J.; Sletten, Ronald S.

    2006-01-01

    Tricalcium silicate was hydrated at 274, 278, 283, 298, and 313 K in stirred suspensions of saturated CaO solutions under a nitrogen-gas atmosphere until the end of deceleratory period. The suspension conductivities and energy flows were measured continuously. The individual reaction rates for tricalcium silicate dissolution, calcium silicate hydrate precipitation, and calcium hydroxide precipitation were calculated from these measurements. The results suggest that the proportion of tricalcium silicate dissolved was determined by the rate of tricalcium silicate dissolution and the time to very rapid calcium hydroxide precipitation. The time to very rapid calcium hydroxide precipitation was more sensitive to changes in temperature than was the rate of tricalcium silicate dissolution, so that the proportion of tricalcium silicate hydration dissolved by the deceleratory period increased with decreasing temperature. The average chain length of the calcium silicate hydrate ascertained by magic-angle spinning nuclear magnetic resonance spectroscopy increased with increasing temperature

  9. A comparison of three dimensional change in maxillary complete dentures between conventional heat polymerizing and microwave polymerizing techniques

    Directory of Open Access Journals (Sweden)

    Shinsuke Sadamori

    2007-03-01

    Full Text Available The purpose of this study was to measure and compare two different polymerizing processes, heat polymerizing (HP and microwave polymerizing (MP, on the three dimensional changes in the fitting surface and artificial teeth of maxillary complete dentures. A threedimensional coordinate measurement system was used to record distortion of the specimens. The distortion of the fitting surface was measured from the reference plane on the fitting side from which a coordinate system was set, and the movement of the artificial teeth and the distortion of the polished surface was measured from the reference plane of the artificial tooth side, from which a coordinate system was set. It was clearly showed that various distortions of denture specimens after polymerization process can be measured with this three-coordinate measuring machine. The study showed that the overall distortion of the fitting surface in HP specimens was shown to be larger than in MP ones.

  10. Photonic devices based on patterning by two photon induced polymerization techniques

    Science.gov (United States)

    Fortunati, I.; Dainese, T.; Signorini, R.; Bozio, R.; Tagliazucca, V.; Dirè, S.; Lemercier, G.; Mulatier, J.-C.; Andraud, C.; Schiavuta, P.; Rinaldi, A.; Licoccia, S.; Bottazzo, J.; Franco Perez, A.; Guglielmi, M.; Brusatin, G.

    2008-04-01

    Two and three dimensional structures with micron and submicron resolution have been achieved in commercial resists, polymeric materials and sol-gel materials by several lithographic techniques. In this context, silicon-based sol-gel materials are particularly interesting because of their versatility, chemical and thermal stability, amount of embeddable active compounds. Compared with other micro- and nano-fabrication schemes, the Two Photon Induced Polymerization is unique in its 3D processing capability. The photopolymerization is performed with laser beam in the near-IR region, where samples show less absorption and less scattering, giving rise to a deeper penetration of the light. The use of ultrashort laser pulses allows the starting of nonlinear processes like multiphoton absorption at relatively low average power without thermally damaging the samples. In this work we report results on the photopolymerization process in hybrid organic-inorganic films based photopolymerizable methacrylate-containing Si-nanobuilding blocks. Films, obtained through sol-gel synthesis, are doped with a photo-initiator allowing a radical polymerization of methacrylic groups. The photo-initiator is activated by femtosecond laser source, at different input energies. The development of the unexposed regions is performed with a suitable solvent and the photopolymerized structures are characterized by microscopy techniques.

  11. Core-Shell-Structured Copolyaniline-Coated Polymeric Nanoparticle Suspension and Its Viscoelastic Response under Various Electric Fields

    Directory of Open Access Journals (Sweden)

    Il-Jae Moon

    2015-08-01

    Full Text Available Semi-conducting poly(n-methylaniline (PNMA-coated poly(methyl methacrylate (PMMA composite nanoparticles were synthesized using cross-linked and grafted PMMA particles as a core, and then, the PNMA shell was coated via chemical oxidative polymerization on the surface of modified PMMA nanoparticles. Their electroresponsive electrorheological characteristics when dispersed in silicone were confirmed under applied electric fields using a rotational rheometer, focusing on their viscoelastic response. Using a frequency sweep test, the frequency dependence of both the storage and loss moduli was confirmed to increase upon increasing the electric field, with a stable plateau regime over the entire angular frequency range.

  12. In-situ Polymerization of Polyaniline/Polypyrrole Copolymer using Different Techniques

    Science.gov (United States)

    Hammad, A. S.; Noby, H.; Elkady, M. F.; El-Shazly, A. H.

    2018-01-01

    The morphology and surface area of the poly(aniline-co-pyrrole) copolymer (PANPY) are important properties which improve the efficiency of the copolymer in various applications. In this investigation, different techniques were employed to produce PANPY in different morphologies. Aniline and pyrrole were used as monomers, and ammonium peroxydisulfate (APS) was used as an oxidizer with uniform molar ratio. Rapid mixing, drop-wise mixing, and supercritical carbon dioxide (ScCO2) polymerization techniques were appointed. The chemical structure, crystallinity, porosity, and morphology of the composite were distinguished by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Brunauer, Emmett and Teller (BET) analysis, and transmission electron microscopy (TEM) respectively. The characterization tests indicated that the polyaniline/polypyrrole copolymer was successfully prepared with different morphologies. Based on the obtained TEM, hollow nanospheres were formed using rapid mixing technique with acetic acid that have a diameter of 75 nm and thickness 26 nm approximately. Also, according to the XRD, the produced structures have a semi- crystalline structure. The synthesized copolymer with ScCO2-assisted polymerization technique showed improved surface area (38.1 m2/g) with HCl as dopant.

  13. Analysis of ultrasonic techniques for the characterization of microfiltration polymeric membranes

    International Nuclear Information System (INIS)

    Lucas, Carla S.; Baroni, Douglas B.; Costa, Antonio M.L.M.; Bittencourt, Marcelo S.Q.

    2009-01-01

    The use of polymeric membranes is extremely important in several industries such as nuclear, biotechnology, chemical and pharmaceutical. In the nuclear area, for instance, systems based on membrane separation technologies are currently being used in the treatment of radioactive liquid effluent, and new technologies using membranes are being developed at a great rate. The knowledge of the physical characteristics of these membranes, such as, pore size and the pore size distribution, is very important to the membranes separation processes. Only after these characteristics are known is it possible to determine the type and to choose a particular membrane for a specific application. In this work, two ultrasonic non destructive techniques were used to determine the porosity of membranes: pulse echo and transmission. A 25 MHz immersion transducer was used. Ultrasonic signals were acquired, for both techniques, after the ultrasonic waves passed through a microfiltration polymeric membrane of pore size of 0.45 μm and thickness of 180 μm. After the emitted ultrasonic signal crossed the membrane, the received signal brought several information on the influence of the membrane porosity in the standard signal of the ultrasonic wave. The ultrasonic signals were acquired in the time domain and changed to the frequency domain by application of the Fourier Fast Transform (FFT), thus generating the material frequency spectrum. For the pulse echo technique, the ultrasonic spectrum frequency changed after the ultrasonic wave crossed the membrane. With the transmission technique there was only a displacement of the ultrasonic signal at the time domain. (author)

  14. Synthesis and Characterization of Nanofibrous Polyaniline Thin Film Prepared by Novel Atmospheric Pressure Plasma Polymerization Technique.

    Science.gov (United States)

    Park, Choon-Sang; Kim, Dong Ha; Shin, Bhum Jae; Tae, Heung-Sik

    2016-01-11

    This work presents a study on the preparation of plasma-polymerized aniline (pPANI) nanofibers and nanoparticles by an intense plasma cloud type atmospheric pressure plasma jets (iPC-APPJ) device with a single bundle of three glass tubes. The nano size polymer was obtained at a sinusoidal wave with a peak value of 8 kV and a frequency of 26 kHz under ambient air. Discharge currents, photo-sensor amplifier, and optical emission spectrometer (OES) techniques were used to analyze the plasma produced from the iPC-APPJ device. Field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), gas chromatography-mass spectrometry (GC-MS), and gel permeation chromatography (GPC) techniques were used to analyze the pPANI. FE-SEM and TEM results show that pPANI has nanofibers, nanoparticles morphology, and polycrystalline characteristics. The FT-IR and GC-MS analysis show the characteristic polyaniline peaks with evidence that some quinone and benzene rings are broken by the discharge energy. GPC results show that pPANI has high molecular weight ( M w ), about 533 kDa with 1.9 polydispersity index (PDI). This study contributes to a better understanding on the novel growth process and synthesis of uniform polyaniline nanofibers and nanoparticles with high molecular weights using the simple atmospheric pressure plasma polymerization technique.

  15. Synthesis and Characterization of Nanofibrous Polyaniline Thin Film Prepared by Novel Atmospheric Pressure Plasma Polymerization Technique

    Directory of Open Access Journals (Sweden)

    Choon-Sang Park

    2016-01-01

    Full Text Available This work presents a study on the preparation of plasma-polymerized aniline (pPANI nanofibers and nanoparticles by an intense plasma cloud type atmospheric pressure plasma jets (iPC-APPJ device with a single bundle of three glass tubes. The nano size polymer was obtained at a sinusoidal wave with a peak value of 8 kV and a frequency of 26 kHz under ambient air. Discharge currents, photo-sensor amplifier, and optical emission spectrometer (OES techniques were used to analyze the plasma produced from the iPC-APPJ device. Field emission scanning electron microscopy (FE-SEM, transmission electron microscopy (TEM, Fourier transform infrared spectroscopy (FT-IR, gas chromatography-mass spectrometry (GC-MS, and gel permeation chromatography (GPC techniques were used to analyze the pPANI. FE-SEM and TEM results show that pPANI has nanofibers, nanoparticles morphology, and polycrystalline characteristics. The FT-IR and GC-MS analysis show the characteristic polyaniline peaks with evidence that some quinone and benzene rings are broken by the discharge energy. GPC results show that pPANI has high molecular weight (Mw, about 533 kDa with 1.9 polydispersity index (PDI. This study contributes to a better understanding on the novel growth process and synthesis of uniform polyaniline nanofibers and nanoparticles with high molecular weights using the simple atmospheric pressure plasma polymerization technique.

  16. Microcalorimetric measurements of heat production in human erythrocytes. IV. Comparison between different calorimetric techniques, suspension media, and preparation methods.

    Science.gov (United States)

    Monti, M; Wadsö, I

    1976-10-01

    Heat production in human erythrocytes from healthy subjects has been measured under different experimental conditions. Simultaneous measurements were made on the same samples using different types of microcalorimeters: a static ampoule calorimeter, an air perfusion calorimeter, and a flow calorimeter. Obtained heat effect values for specified standard conditions, P degrees, were within uncertainty limits the same for the different calorimeters. Cells were suspended either in autologous plasma or in a phosphate buffer. P degrees values for buffer suspensions were significantly higher than those for plasma suspensions. Erythrocyte samples prepared by the column adsorption technique gave higher P degrees values than those obtained by a conventional centrifugation procedure.

  17. Molecularly imprinted microspheres synthesized by a simple, fast, and universal suspension polymerization for selective extraction of the topical anesthetic benzocaine in human serum and fish tissues.

    Science.gov (United States)

    Sun, Hui; Lai, Jia-Ping; Chen, Fang; Zhu, De-Rong

    2015-02-01

    A simple, fast, and universal suspension polymerization method was used to synthesize the molecularly imprinted microspheres (MIMs) for the topical anesthetic benzocaine (BZC). The desired diameter (10-20 μm) and uniform morphology of the MIMs were obtained easily by changing one or more of the synthesis conditions, including type and amount of surfactant, stirring rate, and ratio of organic to water phase. The MIMs obtained were used as a molecular-imprinting solid-phase-extraction (MISPE) material for extraction of BZC in human serum and fish tissues. The MISPE results revealed that the BZC in these biosamples could be enriched effectively after the MISPE operation. The recoveries of BZC on MIMs cartridges were higher than 90% (n = 3). Finally, an MISPE-HPLC method with UV detection was developed for highly selective extraction and fast detection of trace BZC in human serum and fish tissues. The developed method could also be used for the enrichment and detection of BZC in other complex biosamples.

  18. Emulsion Polymerization of Etyl Acrylate: The Effect of Surfactant, Initiator Concentration and PolymerizationTechnique on Particle Size Distribution

    OpenAIRE

    Nitri Arinda; Emil Budianto; Helmiyati

    2009-01-01

    Emulsion polymerization was conducted using ethyl acrylate monomer. Theeffect of sodium lauryl sulfate concentration, ammonium persulfate concentration, the various of polymerizationtechniques and feeding time to the conversion, particle size and its distribution were observed. The purpose of thisresearch is to obtain the optimum condition of ethyl acrylate homopolymer with particle size around 100 nm, to get theparticle size distribution monodisperse and to get solid content value of the exp...

  19. Application of polymerization techniques to the treatment of woods gorged with water

    Energy Technology Data Exchange (ETDEWEB)

    Detanger, B; Ramiere, R; de Tassigny, C; Eymery, R; de Nadaillac, L

    1973-05-01

    From international conference on application of nuclear data in the field of work of art; Rome-Venice, Italy (24 May 1973). Wooden objects from stagnant or flowing waters have great value for the study of prehistory and protohistory. The preservation of these objects offers great difficulties as the elimination of the water causes them to crack, warp, or sag irreversibly. Ancient water-saturated woods were studied botanically, physicochemically, and biologically in order to develop techniques for their preservation in their original form. The studies showed that the simultaneous use of a technique of liquid-liquid extraction of the water and the polymerization under gamma radiation of the monomer introduced by substitution offers possibilities which merit a more in-depth study. (JSR)

  20. Reciclagem de poli(estireno-divinilbenzeno via processo de polimerização em massa-suspensão Recycling of styrene-divinylbenzene via mass-suspension polymerization process

    Directory of Open Access Journals (Sweden)

    Nathália M. Campelo

    2013-01-01

    Full Text Available O presente trabalho trata da reutilização de resinas de troca iônica a base de estireno-divinil benzeno (Sty-DVB na síntese de materiais poliméricos. Partículas micrométricas de poliestireno e poli(estireno-acrilato de etila foram obtidas via processo de polimerização sequencial do tipo massa-suspensão. A técnica experimental proposta mostrou-se bastante apropriada para uma boa dispersão da carga microparticulada de Sty-DVB na matriz polimérica termoplástica. O material final apresentou boa estabilidade térmica, e perfil de degradação similar ao do poliestireno puro. Observou-se também que partículas poliméricas com morfologia esférica podem ser obtidas. Além disso, a incorporação de acrilato de etila à cadeia polimérica do poliestireno minimiza o efeito indesejável de fratura nas partículas poliméricas, melhorando as propriedades mecânicas do material final.This work illustrates the reuse of ion exchange resins based on crosslinked styrene-divinyl benzene copolymer (Sty-DVB for the production of polymeric materials. Micro-sized particles of polystyrene and poly(styrene-ethyl acrylate were obtained by mass-suspension sequential polymerization process. With the proposed experimental technique it was possible to perform proper dispersion of the Sty-DVB in the thermoplastic matrix of polystyrene. The final material showed good thermal stability, and a degradation profile similar to that for pure polystyrene. It was also observed that polymer particles with spherical morphology can be obtained. In addition, the incorporation of ethyl acrylate into the polystyrene chains minimizes the undesirable effect of fracture in polymeric particles, improving the mechanical properties of the final material.

  1. Histamine-imprinted microspheres: Comparison between conventional and raft-mediated polymerization techniques

    International Nuclear Information System (INIS)

    Romano, Edwin F. Jr.; So, Regina C.; Holdsworth, Clovia I.

    2015-01-01

    Molecularly imprinted microspheres (MIM) were synthesized via conventional free radical polymerization (CTP) and RAFT-mediated controlled radical polymerization (CRP) method using histamine as the template molecule. Optimal polymerization conditions were achieved using 4%(w/w) monomer feed concentration with 80=90% EGDMA as crosslinker, and histamine: MAA ratio of 1:4 in acetonitrile at 60°C for 24 hours. The size of CTP-M90 and CTP-M80 imprinted microspheres are comparable with that of RAFT polymer CRP-M80 at 264.5 ±12 nm in the swollen (DLS-DMSO) and collapsed state (SEM). For the CTP method, the presence of the template allows for a bigger particle size compared to the non-imprinted counterpart (NIM). Further, controlled growth was observed for the CRP technique, where the size of the imprinted microsphere, CRP-M80, is comparable to CRP-N80. The binding studies of CTP and CRP microspheres toward histamine were studied at concentrations well below biding with buffer concentration of 25mM at pH7. Results showed that the binding isotherms were found to conform to the Freundlich model. Moreover, results revealed that the difference in binding capacity (N) between MIM and NIM imparted by the imprinting process is significantly higher in CTP-80 (26 μmol/g) than both CTP-90 and CRP-80 (9 μmol/g). Non-competitive and competitive binding assays with L-histidine, imidazole, and tryptamine using CTP-80 and CRP-80 were also carried out. MIMs were shown to exhibit binding preference towards the template. (author)

  2. Evaluation of internal adaptation of Class V resin composite restorations using three techniques of polymerization

    Directory of Open Access Journals (Sweden)

    José Carlos Pereira

    2007-02-01

    Full Text Available OBJECTIVE: The purpose of this in vitro study was to evaluate the internal adaptation of Class V composite restorations to the cavity walls using three different techniques of polymerization. METHODS: Standard cavities were prepared on the buccal and lingual surfaces of 24 extracted human third molars with margins located above and below the cementoenamel junction. Restorations were placed in one increment using two restorative systems: 3M Filtek A110/ Single Bond (M and 3M Filtek Z250/ Single Bond (H in the same tooth, randomly in the buccal and lingual surfaces. Resin composites were polymerized using three techniques: Group 1 - Conventional (60 s - 600 mW/cm²; Group 2 - Soft-start (20 s - 200 mW/cm² , 40 s - 600 mW/cm²; Group 3 - Pulse Activation (3 s - 200 mW/cm², 3-min hiatus, 57 s - 600 mW/cm². Buccolingual sections were polished, impressions taken and replicated. Specimens were assessed under scanning electron microscopy up to X1000 magnification. Scores were given for presence or absence of gaps (0 - no gap; 1 - gap in one wall; 2 - gap in two walls; 3 - gap in three walls. RESULTS: The mean scores of the groups were (±SD were: G1M-3.0 (± 0.0; G2M-2.43 (± 0.8; G3M- 1.71 (± 0.9; G1H- 2.14 (± 1.2; G2H- 2.00 (± 0.8; G3H- 1.67 (± 1.1. Data were analyzed using Kruskal-Wallis and Dunnet's tests. No statistically significant difference (p>0.05 was found among groups. Gaps were observed in all groups. CONCLUSIONS: The photocuring technique and the type of resin composite had no influence on the internal adaptation of the material to the cavity walls. A positive effect was observed when the slow polymerization techniques were used.

  3. Volume Recovery of Polymeric Glasses: Application of a Capacitance-based Measurement Technique

    Science.gov (United States)

    Sakib, Nazam; Simon, Sindee

    Glasses, including polymeric glasses, are inherently non-equilibrium materials. As a consequence, the volume and enthalpy of a glass evolve towards equilibrium in a process termed structural recovery. Several open questions and new controversies remain unanswered in the field. Specifically, the presence of intermediate plateaus during isothermal structural recovery has been reported in recent enthalpy work. In addition, the dependence of the relaxation time on state variables and thermal history is unclear. Dilatometry is particularly useful for structural recovery studies because volume is an absolute quantity and volumetric measurements can be done in-situ. A capillary dilatometer, fitted with a linear variable differential transducer, was used previously to measure volume recovery of polymeric glass formers in our laboratory. To improve on the limitations associated with that methodology, including competition between the range of measurements versus the sensitivity, a capacitance-based technique has been developed following the work of Richert, 2010. The modification is performed by converting the glass capillary dilatometer into a cylindrical capacitor. For precision in capacitance data acquisition, an Andeen-Hagerling ultra-precision capacitance bridge (2550A, 1 kHz) is used. The setup will be tested by performing the signatures of structural recovery as described by Kovacs, 1963. Experiments are also planned to address the open questions in the field.

  4. Influence Of Initiator Types And Emulsion Polymerization Techniques To Particle Size Of Copolymerization Styrene-Butyl Acrylate-Methyl Methacrylate

    Directory of Open Access Journals (Sweden)

    Ariyanti Sarwono

    2008-11-01

    Full Text Available Influence of initiator types and emulsion polymerization techniques to particle size of copolymerization styrene-butyl acrylate-methyl methacrylate. Copoly(styrene/butyl acrylic/methyl methacrylic was prepared by emulsion polymerization method. This paper describes effect of insiator types i.e. ammonium persulfate (APS, hydrogen peroxide, ters-butyl peroxide (TBHP, initiator redox (H2O2/ascorbic acid and polymerization techniques i.e. batch and semicontinue to particle size distribution of copoly(styrene/butyl acrylic/methyl methacrylic. Initiator TBHP and H2O2 could not initiate copolymerization properly, but initiator APS and redox initiate copolymerization with batch and semi continue techniques could well perform. The higher concentration of APS, the greater particle size of the copolymer, but the copolymer is polymodal. Initiator redox (H2O2/ascorbic acid produced greater particle size than initiator redox (ascorbic acid/ H2O2.

  5. A highly flexible polymerization technique to prepare fluorescent nanospheres for trace ammonia detection

    International Nuclear Information System (INIS)

    Waich, K.; Sandholzer, M.; Mayr, T.; Slugovc, C.; Klimant, I.

    2010-01-01

    The preparation of pH-sensitive nanospheres by emulsion polymerization for the detection of trace levels of ammonia is described. A fluorescent, polymerizable xanthene dye was copolymerized with styrene, crosslinkers and further copolymers aimed at enhancing the sensitivity to obtain materials for sensing of ammonia. A half-seeded technique was used to obtain stable emulsions of the monomers which were cured to obtain nanospheres with covalently attached active components. The nanospheres were embedded in a silicon matrix and the sensor films obtained were investigated regarding their response to ammonia at concentrations between 25 and 1,000 ppb. Sensors containing polystyrene nanospheres crosslinked with divinylbenzene showed the best performance in ammonia measurements exhibiting detection limits (LODs) of less than 25 ppb ammonia.

  6. Comparison of in situ polymerization and solution-dispersion techniques in the preparation of Polyimide/Montmorillonite (MMT) Nanocomposites.

    Science.gov (United States)

    Ahmad, Mansor Bin; Gharayebi, Yadollah; Salit, Mohd Sapuan; Hussein, Mohd Zobir; Shameli, Kamyar

    2011-01-01

    In this paper, Polyimide/Montmorillonite Nanocomposites (PI/MMT NCs), based on aromatic diamine (4-Aminophenyl sulfone) (APS) and aromatic dianhydride (3,3',4,4'-benzophenonetetracarboxylic dianhydride) (BTDA) were prepared using in situ polymerization and solution-dispersion techniques. The prepared PI/MMT NCs films were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The XRD results showed that at the content of 1.0 wt % Organo Montmorillonite (OMMT) for two techniques and 3.0 wt % OMMT for the in situ polymerization technique, the OMMT was well-intercalated, exfoliated and dispersed into polyimide matrix. The OMMT agglomerated when its amount exceeded 10 wt % and 3.0 wt % for solution-dispersion and in situ polymerization techniques respectively. These results were confirmed by the TEM images of the prepared PI/MMT NCs. The TGA thermograms indicated that thermal stability of prepared PI/MMT NCs were increased with the increase of loading that, the effect is higher for the samples prepared by in situ polymerization technique.

  7. Evaluation of shrinkage polymerization and temperature of different acrylic resins used to splinting transfer copings in indirect impression technique

    Science.gov (United States)

    Franco, Ana Paula G. O.; Karam, Leandro Z.; Galvão, José R.; Kalinowski, Hypolito J.

    2015-09-01

    The aim of the present study was evaluate the shrinkage polymerization and temperature of different acrylic resins used to splinting transfer copings in indirect impression technique. Two implants were placed in an artificial bone, with the two transfer copings joined with dental floss and acrylic resins; two dental resins are used. Measurements of deformation and temperature were performed with Fiber Braggs grating sensor for 17 minutes. The results revealed that one type of resin shows greater values of polymerization shrinkage than the other. Pattern resins did not present lower values of shrinkage, as usually reported by the manufacturer.

  8. Measure of pore size in micro filtration polymeric membrane using ultrasonic technique and artificial neural networks

    International Nuclear Information System (INIS)

    Lucas, Carla de Souza

    2009-01-01

    This work presents a study of the pore size in micro filtration polymeric membranes, used in the nuclear area for the filtration of radioactive liquid effluent, in the residual water treatment of the petrochemical industry, in the electronic industry for the ultrapure water production for the manufacture of conductors and laundering of microcircuits and in many other processes of separation. Diverse processes for measures of pores sizes in membranes exist, amongst these, electronic microscopy, of bubble point and mercury intrusion porosimetry, however the majority of these uses destructive techniques, of high cost or great time of analysis. The proposal of this work is to measure so great of pore being used ultrasonic technique in the time domain of the frequency and artificial neural networks. A receiving/generator of ultrasonic pulses, a immersion transducer of 25 MHz was used, a tank of immersion and microporous membranes of pores sizes of 0,2 μm, 0,4 μm, 0,6 μm, 8 μm, 10 μm and 12 μm. The ultrasonic signals after to cover the membrane, come back to the transducer (emitting/receiving) bringing information of the interaction of the signal with the membranes. These signals had been used for the training of neural networks, and these had supplied the necessary precision the distinction of the same ones. Soon after, technique with the one of electronic microscopy of sweepings was made the comparison of this. The experiment showed very resulted next to the results gotten with the MEV, what it indicated that the studied technique is ideal for measure of pore size in membranes for being not destructive and of this form to be able to be used also on-line of production. (author)

  9. Homogenization Effect on Nanostructure and Conductivity of Polyaniline Nanofibre Synthesis by Mini-Emulsion Polymerization Technique

    Science.gov (United States)

    Mohammad, M.; Kamarudin, S.; Mohamed, N. H.; Asim, N.; Sopian, K.

    2017-12-01

    Nanofibre polyaniline (n-PANI) was synthesized by mini-emulsion polymerization technique between aniline monomer and ammonium persulfate as an oxidant using homogenizer. The synthesis was performed by optimizing mixing speed from 10,000 to 30,000 rpm and time reaction between 0.5 to 24 hours at fixed monomer to oxidant molar ratio 4:1. An attempt has been made to investigate on how the speed of homogenizer affects the size and conductivity of n-PANI. The formation of n-PANI chain was confirmed by Fourier transform infrared spectroscopy (FTIR). The X-ray diffraction (XRD) spectra revealed PANI crystalline nature. Hall effect measurement used indicated that the electrical conductivity of n-PANI is increased with homogenizer speed from 5.2 to 17.5 Scm-1. The morphological properties of n-PANI performed by scanning electron microscopy (SEM) show the decreasing size of n-PANI from 50-60 nm to 20-30 nm with the increment homogenizer speed. This study indicated the optimum speed parameter of homogenizer play a role in reducing the nanostructured size and thus, increasing the electrical conductivity of n-PANI.

  10. Modelagem da polimerização simultânea de estireno em suspensão e emulsão Modeling styrene simultaneous suspension and emulsion polymerization systems

    Directory of Open Access Journals (Sweden)

    Marcelo K. Lenzi

    2004-06-01

    Full Text Available Apesar dos processos de polimerização em suspensão e emulsão serem processos heterogêneos, cada um origina características peculiares para a distribuição de tamanho de partículas, distribuição de pesos moleculares, taxa de nucleação das partículas de polímero, taxa de polimerização, entre outras. Neste trabalho, são realizadas polimerizações de estireno simultaneamente em suspensão e emulsão. A carga inicial do reator equivale à receita de uma polimerização em suspensão tradicional, enquanto os constituintes da emulsão são adicionados ao longo da batelada. Analisa-se como as propriedades finais do polímero e o curso da polimerização dependem do momento em que a carga característica da emulsão é adicionada à polimerização em suspensão. Apresenta-se, também, um modelo matemático para a descrição do sistema, sendo que o modelo proposto possui boa concordância com dados experimentais de conversão, pesos moleculares médios e curva de distribuição de pesos moleculares. A morfologia da partícula de polímero e os pesos moleculares médios mudam significativamente, dependendo do momento da adição da emulsão, podendo até mesmo ser obtidas curvas de distribuição de pesos moleculares bimodais. Verificou-se que as partículas apresentam características do tipo núcleo/casca, sendo o núcleo formado pelas partículas obtidas pela polimerização em suspensão e a casca formada pelas partículas do processo em emulsão.Although both emulsion and suspension polymerization processes are performed in heterogeneous media, each process presents its own typical characteristics, such as the particle size distribution, molecular weight distribution, polymer particle nucleation rates, rates of polymerization, and so on. In this work styrene polymerizations are carried out in suspension and emulsion processes simultaneously. The initial reactor charge resembles the recipe of standard styrene suspension

  11. Preparation of Dimethylaminoethylmethacrylate Grafted Polymeric Adsorbent by Using Radiation-Induced Grafting Technique for Removal of Anions

    International Nuclear Information System (INIS)

    Kavakli, P. A.

    2006-01-01

    The development of efficient separation and purification techniques is very important from industrial, environmental and economic points of view. Polymeric materials having polyfunctional groups such as carboxylic, amide, nitrile, iminodiacetic acid, amidoxime, and ammonium groups, etc., not only possess good hydrophilic properties, but also have good ion exchange properties which make them suitable for metal recovery from aqueous solutions. Radiation induced grafting is a powerful technique capable of controlling the introduction of various functional groups to the polymeric materials, keeping the original properties and especially the mechanical strength of the base material, and thus, allowing the synthesis of more stable polymeric adsorbents. The main objective of this study was to develop special polymeric adsorbents to remove NOx and PO 4 anions from aqueous systems. For this purpose, a novel nonwoven fabric was prepared by radiation-induced graft polymerization of imethylaminoethylmethacrylate (DMAEMA) onto polypropylene coated polyethylene nonwoven fabric. The trunk polymer was irradiated by electron beam at a voltage of 2 MeV and a current of 3 mA in a nitrogen atmosphere at dry-ice temperature at different doses. The degree of grafting was determined as a function of the total dose, monomer concentration, temperature, and reaction time. It was found that the degree of grafting of grafted polymer was greatly affected by reaction conditions. Grafting conditions were optimized, and about 150 % degree of grafting samples was used for further experiments. DMAEMA grafted polymer was later protonated by using acid solution to prepare adsorbent for the removal of anions. Adsorption experiments were performed in column mode for removal of phosphate. Approximately 2000 bed volumes of phosphate-free water can be produced from 10 ppb phosphate solution at high space velocity

  12. Technique of radiation polymerization in fine art conservation: a potentially new method of restoration and preservation. [Uv and electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Garnett, J.L. (Univ. of New South Wales, Kensington, Australia); Major, G.

    1982-01-01

    The technique of using radiation polymerization for the restoration and preservation of art treasures is considered. The processes discussed include both radiation grafting and rapid cure procedures, particularly reactions initiated by uv and eb. Representative examples where the technique has already been used are treated including typical applications with paintings, tapestries, leather and archival repair. The structure of the monomers and oligomers used in both grafting and rapid cure systems is outlined. The experimental conditions where grafting may occur during radiation rapid cure processing are discussed. Possible future developments of the technique are outlined. 1 figure, 8 tables.

  13. Surface-Initiated Atom Transfer Radical Polymerization and Electrografting Technique as a Means For Attaining Tailor-Made Polymer Coatings

    DEFF Research Database (Denmark)

    Chernyy, Sergey

    2012-01-01

    strategies for initiator grafting, physicochemical properties of polymer brushes and basic principles of quartz crystal microbalance technique (QCM) are discussed. In Chapter 2 various ATRP conditions are probed. The effects of solvent polarity, monomer concentration, initiator surface density, ligand nature......Atom transfer radical polymerization initiated from a surface of various substrates (SI-ATRP) has become a progressively popular technique for obtaining thin polymer films with predetermined properties. The present work addresses the main features of SI-ATRP with respect to the controllability...... and temperature on the kinetics of methyl methacrylate polymerization are elucidated. The strategy was based on the observation of dry polymer thickness versus time evolution by means of ellipsometry, profilometry and IR spectroscopy. An alternative approach, constituting Chapter 3, was based on optimization...

  14. Influence of Emulsion Polymerization Techniques to Particle Size of Copoly(styrene/butyl acrylate/methyl methacrylate

    Directory of Open Access Journals (Sweden)

    Tresye Utari

    2008-04-01

    Full Text Available In the majority of applications, particle size and particle size distribution are highly significant factors that determine the properties of a polymer dispersion, such as its flow behavior or its stability. For example, a coating material with small particle size will give smooth coating result, good adhesive strength, good water resistance and latex stability. This article describes influence of various emulsion polymerization techniques to particle size of copoly(styrene/butyl acrylate/methyl methacrylate with mix surfactant SDBS linear chain and nonyl fenol (EO10 and initiator ammonium persulphate. DSC data, solid content and IR spectrum showed that copoly(styrene/butyl acrylate/methyl methacrylate was produced. Batch emulsion polymerization technique gave the highest particle size i.e. 615 nm and also the highest % conversion of monomer i.e. 97%. The more concentration of monomer was seeded to initial charge gave greater particle size and greater poly dispersity index.

  15. Shear Rheology of a Suspension of Deformable Solids in Viscoelastic Fluid via Immersed Boundary Techniques

    Science.gov (United States)

    Guido, Christopher; Shaqfeh, Eric

    2017-11-01

    The simulation of fluids with suspended deformable solids is important to the design of microfluidic devices with soft particles and the examination of blood flow in complex channels. The fluids in these applications are often viscoelastic, motivating the development of a high-fidelity simulation tool with general constitutive model implementations for both the viscoelastic fluid and deformable solid. The Immersed Finite Element Method (IFEM) presented by Zhang et al. (2007) allows for distinct fluid and solid grids to be utilized reducing the need for costly re-meshing when particles translate. We discuss a modified version of the IFEM that allows for the simulation of deformable particles in viscoelastic flows. This simulation tool is validated for simple Newtonian shear flows with elastic particles that obey a Neo-Hookean Law. The tool is used to further explore the rheology of a dilute suspension of Neo-Hookean particles in a Giesekus fluid. The results show that dilute suspensions of soft particles have viscosities that decrease as the Capillary number becomes higher in both the case of a Newtonian and viscoelastic fluid. A discussion of multiple particle results will be included. NSF CBET-1066263 and 1066334.

  16. A Solvent-Free Surface Suspension Melt Technique for Making Biodegradable PCL Membrane Scaffolds for Tissue Engineering Applications

    Directory of Open Access Journals (Sweden)

    Ratima Suntornnond

    2016-03-01

    Full Text Available In tissue engineering, there is limited availability of a simple, fast and solvent-free process for fabricating micro-porous thin membrane scaffolds. This paper presents the first report of a novel surface suspension melt technique to fabricate a micro-porous thin membrane scaffolds without using any organic solvent. Briefly, a layer of polycaprolactone (PCL particles is directly spread on top of water in the form of a suspension. After that, with the use of heat, the powder layer is transformed into a melted layer, and following cooling, a thin membrane is obtained. Two different sizes of PCL powder particles (100 µm and 500 µm are used. Results show that membranes made from 100 µm powders have lower thickness, smaller pore size, smoother surface, higher value of stiffness but lower ultimate tensile load compared to membranes made from 500 µm powder. C2C12 cell culture results indicate that the membrane supports cell growth and differentiation. Thus, this novel membrane generation method holds great promise for tissue engineering.

  17. Copolymers containing phosphorescent iridium(III) complexes obtained by free and controlled radical polymerization techniques

    NARCIS (Netherlands)

    Ulbricht, C.; Becer, C.R.; Winter, A.; Veldman, D.; Schubert, U.S.

    2008-01-01

    A methacrylate-functionalized phosphorescent Ir(III)-complex has been synthesized, characterized, and applied as a monomer in radical copolymerizations. Together with methyl methacrylate, the complex has been copolymerized under free radical polymerization conditions. Aiming for host-guest-systems,

  18. Modification of glass fibers to improve reinforcement: a plasma polymerization technique

    Czech Academy of Sciences Publication Activity Database

    Çökeliler, D.; Erkut, S.; Zemek, Josef; Biederman, H.; Mutlu, M.

    2007-01-01

    Roč. 23, č. 3 (2007), s. 335-342 ISSN 0109-5641 Institutional research plan: CEZ:AV0Z10100521 Keywords : plasma polymerization * glos-discharge * E-glass fibros * ethylendiamine * 2-hydroxyethyl methacrystalate * triethyleneglycoldimethylether * fibre-reinforced composite ( FRC) Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.990, year: 2007

  19. Surface-initiated Atom Transfer Radical Polymerization - a Technique to Develop Biofunctional Coatings

    DEFF Research Database (Denmark)

    Fristrup, Charlotte Juel; Jankova Atanasova, Katja; Hvilsted, Søren

    2009-01-01

    The initial formation of initiating sites for atom transfer radical polymerization (ATRP) on various polymer surfaces and numerous inorganic and metallic surfaces is elaborated. The subsequent ATRP grafting of a multitude of monomers from such surfaces to generate thin covalently linked polymer...

  20. A novel approach to fabricate dye-encapsulated polymeric micro- and nanoparticles by thin film dewetting technique.

    Science.gov (United States)

    Chatterjee, Manosree; Hens, Abhiram; Mahato, Kuldeep; Jaiswal, Namita; Mahato, Nivedita; Nagahanumaiah; Chanda, Nripen

    2017-11-15

    A new method is reported for fabrication of polymeric micro- and nanoparticles from an intermediate patterned surface originated by dewetting of a polymeric thin film. Poly (d, l-lactide-co-glycolide) or PLGA, a biocompatible polymer is used to develop a thin film over a clean glass substrate which dewets spontaneously in the micro-/nano-patterned surface of size range 50nm to 3.5µm. Since another water-soluble polymer, poly vinyl alcohol (PVA) is coated on the same glass substrate before PLGA thin film formation, developed micro-/nano-patterns are easily extracted in water in the form of micro- and nanoparticle mixture of size range 50nm to 3.0µm. This simplified method is also used to effectively encapsulate a dye molecule, rhodamine B inside the PLGA micro-/nanoparticles. The developed dye-encapsulated nanoparticles, PLGA-rhodamine are separated from the mixture and tested for in-vitro delivery application of external molecules inside human lung cancer cells. For the first time, the use of thin film dewetting technique is reported as a potential route for the synthesis of polymeric micro-/nanoparticles and effective encapsulation of external species therein. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Preservation of archaeological artefacts by γ-ray induced polymerization technique

    International Nuclear Information System (INIS)

    Gueven, O.

    1983-01-01

    For the preservation and consolidation of archaeological artefacts irradiation of these objects with γ-rays seems to be a very promising method. In situ polymerization of monomers impregnated in the capillaries and cavities of the objects by γ-rays provides a simultaneous sterilization and consolidation effect. In the present work this method of preservation is applied to some XIIth century ceramic findings belonging to Seljuk period found in South-East Anatolia. Monomer impregnation is restricted to the surfaces of the objects. The colored figures and structures which are present but not perceptible on these objects became fully apparent upon polymerizing hydrophilic monomers on their surfaces. Crosslinking of the top polymer layer further provides a permanent protection of the substrate material. (author)

  2. Characterization of nylon 6/poly(propylene oxide) polymeric mixture by combined NMR techniques

    International Nuclear Information System (INIS)

    Costa, Dilma Alves; Oliveira, Clara Marize F.; Tavares, Maria Ines B.

    1995-01-01

    Polymeric mixtures aim to improve physical or chemical properties of materials. This mixtures can be compatible or not. The compatibility between polymers determine changes of properties. This work has presented a detailed study where nylon 6 and poly(propylene oxide) mixture was analysed by 13 C NMR in the solid state, and NMR spectra were shown and explained. The molecular mobility as well as the compatibility have been observed and discussed

  3. The influence of "C-factor" and light activation technique on polymerization contraction forces of resin composite

    Directory of Open Access Journals (Sweden)

    Sérgio Kiyoshi Ishikiriama

    2012-12-01

    Full Text Available OBJECTIVES: This study evaluated the influence of the cavity configuration factor ("C-Factor" and light activation technique on polymerization contraction forces of a Bis-GMA-based composite resin (Charisma, Heraeus Kulzer. MATERIAL AND METHODS: Three different pairs of steel moving bases were connected to a universal testing machine (emic DL 500: groups A and B - 2x2 mm (CF=0.33, groups C and D - 3x2 mm (CF=0.66, groups e and F - 6x2 mm (CF=1.5. After adjustment of the height between the pair of bases so that the resin had a volume of 12 mm³ in all groups, the material was inserted and polymerized by two different methods: pulse delay (100 mW/cm² for 5 s, 40 s interval, 600 mW/cm² for 20 s and continuous pulse (600 mW/cm² for 20 s. Each configuration was light cured with both techniques. Tensions generated during polymerization were recorded by 120 s. The values were expressed in curves (Force(N x Time(s and averages compared by statistical analysis (ANOVA and Tukey's test, p<0.05. RESULTS: For the 2x2 and 3x2 bases, with a reduced C-Factor, significant differences were found between the light curing methods. For 6x2 base, with high C-Factor, the light curing method did not influence the contraction forces of the composite resin. CONCLUSIONS: Pulse delay technique can determine less stress on tooth/restoration interface of adhesive restorations only when a reduced C-Factor is present.

  4. Preparation of antifouling ultrafiltration membranes via irradiation induced graft polymerization technique

    International Nuclear Information System (INIS)

    Deng Bo; Liu Zhognying; Lu Xiaofeng; Li Jingye; Yang Xuanxuan; Yu Ming; Zhang Bowu

    2010-01-01

    PVDF powders were irradiated in air at dose of 15 kGy by using gamma-rays. Macromolecular peroxides transformed from free radicals in the irradiated PVDF powders in air can be preserved for long-term at appropriate temperature stably. By mixing acrylic monomers with irradiated PVDF powders then the graft polymerization can be initiated by heating. Then a series of hydrophilic ultrafiltration (UF) membranes were fabricated by dissolving the PVDF-g-PAAc powders in the NMP under phase inversion method. The antifouling performances of UF membranes cast from virgin and grafted PVDF powders were compared. (authors)

  5. Two-photon polymerization technique for microfabrication of CAD-designed 3D scaffolds from commercially available photosensitive materials.

    Science.gov (United States)

    Ovsianikov, Aleksandr; Schlie, Sabrina; Ngezahayo, Anaclet; Haverich, Axel; Chichkov, Boris N

    2007-01-01

    We report on recent advances in the fabrication of three-dimensional (3D) scaffolds for tissue engineering and regenerative medicine constructs using a two-photon polymerization technique (2PP). 2PP is a novel CAD/CAM technology allowing the fabrication of any computer-designed 3D structure from a photosensitive polymeric material. The flexibility of this technology and the ability to precisely define 3D construct geometry allows issues associated with vascularization and patient-specific tissue fabrication to be directly addressed. The fabrication of reproducible scaffold structures by 2PP is important for systematic studies of cellular processes and better understanding of in vitro tissue formation. In this study, 2PP was applied for the generation of 3D scaffold-like structures, using the photosensitive organic-inorganic hybrid polymer ORMOCER (ORganically MOdified CERamics) and epoxy-based SU8 materials. By comparing the proliferation rates of cells grown on flat material surfaces and under control conditions, it was demonstrated that ORMOCER and SU8 are not cytotoxic. Additional tests show that the DNA strand breaking of GFSHR-17 granulosa cells was not affected by the presence of ORMOCER. Furthermore, gap junction conductance measurements revealed that ORMOCER did not alter the formation of cell-cell junctions, critical for functional tissue growth. The possibilities of seeding 3D structures with cells were analysed. These studies demonstrate the great potential of 2PP technique for the manufacturing of scaffolds with controlled topology and properties.

  6. Plasma-polymerized hexamethyldisilazane treated by nitrogen plasma immersion ion implantation technique

    Energy Technology Data Exchange (ETDEWEB)

    Honda, R Y; Mota, R P; Batocki, R G S; Santos, D C R; Nicoleti, T; Kostov, K G; Kayama, M E; Algatti, M A [Laboratorio de Plasma, Faculdade de Engenharia, UNESP, Av. Dr Ariberto Pereira da Cunha-333, 12516-410, Guaratingueta, SP (Brazil); Cruz, N C [Laboratorio de Plasmas Tecnologicos, Unidade Diferenciada, UNESP, Av. Tres de Marco-511, 18085-180, Sorocaba, SP (Brazil); Ruggiero, L, E-mail: honda@feg.unesp.b [Faculdade de Ciencias, UNESP, Av. Luis E. Carrijo Coube 14-1, 17033-360, Bauru, SP (Brazil)

    2009-05-01

    This paper describes the effect of nitrogen Plasma Immersion Ion Implantation (PIII) on chemical structure, refraction index and surface hardness of plasma-polymerized hexamethyldisilazane (PPHMDSN) thin films. Firstly, polymeric films were deposited at 13.56 MHz radiofrequency (RF) Plasma Enhanced Chemical Vapour Deposition (PECVD) and then, were treated by nitrogen PIII from 15 to 60 min. Fourier Transformed Infrared (FTIR) spectroscopy was employed to analyse the molecular structure of the samples, and it revealed that vibrations modes at 3350 cm{sup -1}, 2960 cm{sup -1}, 1650 cm{sup -1}, 1250 cm{sup -1} and 1050 cm{sup -1} were altered by nitrogen PIII. Visible-ultraviolet (vis-UV) spectroscopy was used to evaluate film refractive index and the results showed a slight increase from 1.6 to 1.8 following the implantation time. Nanoindentation revealed a surface hardness rise from 0.5 to 2.3 GPa as PIII treatment time increased. These results indicate nitrogen PIII is very promising in improving optical and mechanical properties of PPHMDSN films.

  7. Techniques for extreme attitude suspension of a wind tunnel model in a magnetic suspension and balance system. Ph.D. Thesis

    Science.gov (United States)

    Parker, David Huw

    1989-01-01

    Although small scale magnetic suspension and balance systems (MSBSs) for wind tunnel use have been in existence for many years, they have not found general application in the production testing of flight vehicles. One reason for this is thought to lie in the relatively limited range of attitudes over which a wind tunnel model may be suspended. Modifications to a small MSBS to permit the suspension and control of axisymmetric models over angles of attack from less than zero to over ninety degrees are reported. Previous work has shown that existing arrangement of ten electromagnets was unable to generate one of the force components needed for control at extreme attitudes. Examination of possible solutions resulted in a simple alteration to rectify this deficiency. To generate the feedback signals to control the suspended model, an optical position sensing system using collimated laser beams and photodiode arrays was installed and tested. An analytical basis was developed for distributing the demands for force and moment needed for model stabilization amonge the electromagnets over the full attitude range. This was implemented by an MSBS control program able to continually adjust the distribution for the instantaneous incidence in accordance with prescheduled data. Results presented demonstrate rotations of models from zero to ninety degrees at rates up to ninety degrees per second, with pitching rates rising to several hundred degrees per second in response to step-change demands. A study of a design for a large MSBS suggests that such a system could be given the capability to control a model in six degrees of freedom over an unlimited angle of attack range.

  8. An investigation on the effects of different polymerization techniques on dimensional changes ofAcropars, an Iranian autopolymerizing acrylic resin

    Directory of Open Access Journals (Sweden)

    Ebadian B

    2004-02-01

    Full Text Available Iranian product, Acropars autopolymerizing acrylic resin is nowadays widely used in"ndental prostheses. Dimensional change is a common problem among Iranian made acrylic resins in making"ncustom trays and record bases, seems to be more than the similar foreign products. In order to achieve a"ntechnique for making a record base with minimum dimensional changes, more research is necessary."nPurpose: The aim of the present study was to determine a curing technique for Iranian autopolymerizing"nacrylic resins leading to the least polymerization shrinkage and the most adaptation between record bases and"nstone casts."nMaterials and Methods: In this experimental study, 40 stone casts were divided into four 10- member group."nFor each group, polymerization shrinkage was determined at three points with one of the following"ntechniques: Bench curing, Curing under a coat of petroleum jelly , Curing in a monomer saturated"natmosphere, Curing in boiled water. Adaptation between bases and stone casts were measured at three points"n(the right and left crests of the ridge and the midpalatal region with a light-measuring microscope. To analyze"nthe data, Variance analysis was used."nResults: The monomer atmosphere technique showed the minimum dimensional changes and the samples in"nboiled water group had the maximum dimensional changes. No statistical differences were observed between"nother groups."nConclusion: More adaptation between record bases and stone casts was observed in monomer atmosphere"npolymerization technique. The differences between bench curing and curing under a coat of petroleum jelly"ntechniques with this method were not statistically significant. Therefore, it is suggested for making base"nrecords with maximum adaptation.

  9. Improvement of a separation method for the reduction of secondary waste from the water-jet abrasive suspension cutting technique

    International Nuclear Information System (INIS)

    Brandauer, M.; Gentes, S.; Heneka, A.; Krauss, C.O.; Geckeis, H.; Plaschke, M.; Schild, D.; Tobie, W.

    2017-01-01

    Full text of publication follows. Disassembling the reactor pressure vessel and its built-in components is a huge challenge in the deconstruction of a nuclear power plant. After being exposed to neutron irradiation for years, the activated components need to be disassembled and packed by remote controlled techniques. Underwater disassembling systems have the advantage of the shielding effect of water against radiation. To avoid the generation of aerosols, cold cutting processes are preferred. A cutting method that meets these requirements is the water-jet abrasive suspension cutting technique (WASS). This method provides high flexibility and is immune towards mechanical stress in the components. During the cutting process, a mixture of abrasive particles and radioactive steel particles from the cut components is generated. Depending on the operational conditions, the amount of this secondary waste increases substantially. Therefore, despite of its intrinsic technical benefits, WASS has a serious disadvantage towards other cutting techniques due to the huge disposal costs of secondary waste. During our previous joint research project between KIT and AREVA GmbH called NENAWAS ('New Disposal Methods for the Secondary Waste Treatment of the Water-jet Abrasive Suspension Cutting Technique', funded by the German ministry for education and research, BMBF), a prototype separation device for WASS secondary waste was developed and tested. Using a magnetic filter, steel particles could be successfully separated from the rest of the secondary waste. The separation process is examined using elemental analysis (ICP-OES) for quantification of the separation grade. Additionally, morphologies of particles and particle aggregates before and after the separation process were examined by scanning electron microscopy (SEM). In the abrasive particle fraction after separation of the steel particles a remaining contamination by tiny steel particles could be detected by elemental and

  10. Morphology-controlled SWCNT/polymeric microsphere arrays by a wet chemical self-assembly technique and their application for sensors

    International Nuclear Information System (INIS)

    Huang Xingjiu; Li Yue; Im, Hyung-Soon; Yarimaga, Oktay; Kim, Ju-Hyun; Jang, Doon-Yoon; Cho, Sung-Oh; Cai Weiping; Choi, Yang-Kyu

    2006-01-01

    Large-scale morphology-controlled SWCNT/polymeric microsphere arrays can be obtained by a wet chemical self-assembly technique. The loading of SWCNTs, the length of SWCNTs, and the size and nature of polymeric microspheres can easily be controlled. Similar results can also be reached using this method for MWCNTs. In both types of CNTs, they form an interesting interactive 'net' structure on spheres and sphere joints. The SWCNT/PS-modified Au electrode was used for detection of uric acid by cyclic voltammetry and single-potential time-based techniques. The preliminary results show that the modified electrode presents good sensitivity and stability to uric acid

  11. Preparation of slowly released male sex hormone drug by radiation polymerization technique and its evaluation in vivo

    International Nuclear Information System (INIS)

    Liu Rueizhi; Lei Shaoqiong; Li Ximing

    1992-01-01

    The radiation polymerization technique was used for immobilization testosterone propionate into crosslinked network of poly hydroxyethyl methacrylate to prepare slowly released male sex hormone drug which is used for testicular prosthesis. The testicular prosthesis was transplanted into the scrotum of male rabbit whose testes was excised 2 months before the transplantation. Then the level of male sex hormone in serum was measured by radioimmunoassay once a week after transplantation. The results of measurement in a period of 6 months were shown that the testicular prosthesis has a stable release of male sex hormone. The testosterone level in serum of the castrated male rabbits rises markedly and finally stabilizes at the level of 429 ± 36 ng/100 ml after transplantation. Macroscopic examination of biopsies taken from the tissues around the testicular prosthesis showed that tissue compatibility was revealed well

  12. Nano-suspension coating as a technique to modulate the drug release from controlled porosity osmotic pumps for a soluble agent.

    Science.gov (United States)

    Bahari, Leila Azharshekoufeh; Javadzadeh, Yousef; Jalali, Mohammad Barzegar; Johari, Peyvand; Nokhodchi, Ali; Shokri, Javad

    2017-05-01

    In controlled porosity osmotic pumps (CPOP), usually finding a single solvent with a capability to dissolve both film former (hydrophobic) and pore former (hydrophilic) is extremely challenging. Therefore, the aim of the present investigation was to tackle the issue associated with controlled porosity osmotic pump (CPOP) system using nano-suspension coating method. In the present study 4-Amino pyridine was used as a highly water soluble drug. In this method, a hydrophilic pore former (sucrose or mannitol) in nano range was suspended in polymeric coating solution using ball-mill. The performance of the prepared formulations was assessed in terms of D 12h (cumulative release percent after 12h), Dev zero (mean percent deviation of drug release from zero order kinetic), t L (lag time of the drug release) and RSQ zero . The results revealed that gelling agent amount (HPMC E 15LV ) in core and pore former concentration in SPM had crucial effect on SPM integrity. All the optimised formulations showed a burst drug release due to fast dissolving nature of the pore formers. Results obtained from scanning electron microscopy demonstrated the formation of nanopores in the membrane where the drug release takes place via these nanopores. Nano suspension coating method can be introduced as novel method in formulation of CPOPs. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Disk suspension method: a novel and safe technique for the retraction of the liver during laparoscopic surgery (with video).

    Science.gov (United States)

    Shibao, Kazunori; Higure, Aiichiro; Yamaguchi, Koji

    2011-08-01

    A good operative field is important for safe operations, but it is sometimes difficult to obtain a satisfactory operative field in laparoscopic upper abdominal surgery. We developed a novel and safe technique for the retraction of the liver and falciform ligament during laparoscopic surgery, and evaluated its technical feasibility and safety. Forty-three patients with gastric cancer were divided into two groups: disk suspension group (DS group; snake retractor and elastic band fixation with a silicon disk), and fixed retractor group (FR group; snake retractor and nonelastic band fixation without a silicon disk). To evaluate liver damage during retraction, we measured the aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels preoperatively and on postoperative day (POD) 1. In the DS group, all liver lobes were adequately retracted and the hepatoduodenal and gastrohepatic ligaments were fully exposed. This procedure took less than 3 min. On the other hand, 5 of 18 patients of the FR group had insufficient surgical fields for laparoscopic gastrectomy because of soft and/or large livers. Although the preoperative AST and ALT levels were not different between the two groups, the DS group did not display increases in both AST and ALT levels, whereas the FR group showed increases in both on POD 1 (AST: 50.2 ± 8.4 IU/l vs. 124.2 ± 37.7 IU/l, P = 0.07; and ALT: 35.6 ± 6.4 IU/l vs. 106.1 ± 36.2 IU/l, P = 0.07). No complications related to the liver retraction were observed in the DS group. However, liver congestion was evident in six patients and minor liver injury in two patients of the FR group during the esophagojejunostomy. The DS method is a simple and safe and provides a better surgical field during laparoscopic surgery of the upper abdomen without damaging the liver.

  14. Influência das condições reacionais nas características de copolímeros de metacrilato de metila e divinilbenzeno obtidos por polimerização em suspensão Influence from the reaction conditions on the characteristics of methyl methacrylate-divinylbenzene copolymers obtained by suspension polymerization

    Directory of Open Access Journals (Sweden)

    Anelise M. Cardoso

    2004-09-01

    Full Text Available Foram sintetizados copolímeros esféricos e porosos à base de metacrilato de metila e divinilbenzeno através de polimerização em suspensão aquosa utilizando metil-etil-cetona (MEK e ciclo-hexano (CH como diluentes. Diferentes estruturas morfológicas foram obtidas através da modificação dos parâmetros reacionais tais como teor de divinilbenzeno e razão MEK/CH. Os copolímeros foram caracterizados por porosimetria de mercúrio, análise de área específica, densidade aparente e microscopia ótica. Foram obtidas estruturas macroporosas com os teores mais altos do DVB e do diluente não-solvatante (CH.Spherical and porous copolymers based on methyl methacrylate and divinylbenzene were synthesized by aqueous suspension polymerization using methyl-ethyl-ketone (MEK and cyclohexane (CH as diluents. Different morphological structures were obtained by modifying the reaction parameters, such as divinylbenzene content and MEK/CH ratio. The copolymers were characterized by several techniques: mercury porosimetry, specific superficial area analyzer, apparent density and optical microcopy. Macroporous structures were obtained when using high content of DVB and of nonsolvatant diluent (CH.

  15. A novel fabrication technique for free-hanging homogeneous polymeric cantilever waveguides

    International Nuclear Information System (INIS)

    Nordström, Maria; Hübner, Jörg; Boisen, Anja; Calleja, Montserrat

    2008-01-01

    We present a novel bonding technique developed for the fabrication of a cantilever-based biosensing system with integrated optical read-out. The read-out mechanism is based on single-mode waveguides fabricated monolithically in SU-8. For optimal operation of the read-out mode, the cantilever waveguides should be homogenous and this bonding technique ensures free-hanging cantilevers that are surrounded by the same material for bottom and top claddings. The bonding step is necessary because SU-8 is a negative resist where free-hanging structures cannot be fabricated directly. This paper gives details on the processing aspects and the parameters of the fabrication steps

  16. A novel fabrication technique for free-hanging homogeneous polymeric cantilever waveguides

    DEFF Research Database (Denmark)

    Nordström, M.; Calleja, M.; Hübner, Jörg

    2008-01-01

    We present a novel bonding technique developed for the fabrication of a cantilever-based biosensing system with integrated optical read-out. The read-out mechanism is based on single-mode waveguides fabricated monolithically in SU-8. For optimal operation of the read-out mode, the cantilever...

  17. Atomic Force Microscopy Techniques for Nanomechanical Characterization: A Polymeric Case Study

    Science.gov (United States)

    Reggente, Melania; Rossi, Marco; Angeloni, Livia; Tamburri, Emanuela; Lucci, Massimiliano; Davoli, Ivan; Terranova, Maria Letizia; Passeri, Daniele

    2015-04-01

    Atomic force microscopy (AFM) is a versatile tool to perform mechanical characterization of surface samples at the nanoscale. In this work, we review two of such methods, namely contact resonance AFM (CR-AFM) and torsional harmonics AFM (TH-AFM). First, such techniques are illustrated and their applicability on materials with elastic moduli in different ranges are discussed, together with their main advantages and limitations. Then, a case study is presented in which we report the mechanical characterization using both CR-AFM and TH-AFM of polyaniline and polyaniniline doped with nanodiamond particles tablets prepared by a pressing process. We determined the indentation modulus values of their surfaces, which were found in fairly good agreement, thus demonstrating the accuracy of the techniques. Finally, the determined surface elastic moduli have been compared with the bulk ones measured through standard indentation testing.

  18. Mechanical and biodegradable properties of porous titanium filled with poly-L-lactic acid by modified in situ polymerization technique.

    Science.gov (United States)

    Nakai, Masaaki; Niinomi, Mitsuo; Ishii, Daisuke

    2011-10-01

    Porous titanium (pTi) can possess a low Young's modulus equal to that of human bone, depending on its porosity. However, the mechanical strength of pTi deteriorates greatly with increasing porosity. On the other hand, certain medical polymers exhibit biofunctionalities, which are not possessed intrinsically by metallic materials. Therefore, a biodegradable medical polymer, poly-L-lactic acid (PLLA), was used to fill in the pTi pores using a modified in-situ polymerization technique. The mechanical and biodegradable properties of pTi filled with PLLA (pTi/PLLA) as fabricated by this technique and the effects of the PLLA filling were evaluated in this study. The pTi pores are almost completely filled with PLLA by the developed process (i.e., technique). The tensile strength and tensile Young's modulus of pTi barely changes with the PLLA filling. However, the PLLA filling improves the compressive 0.2% proof stress of pTi having any porosity and increases the compressive Young's modulus of pTi having relatively high porosity. This difference between the tensile and compressive properties of pTi/PLLA is considered to be caused by the differing resistances of PLLA in the pores to tensile and compressive deformations. The PLLA filled into the pTi pores degrades during immersion in Hanks' solution at 310 K. The weight loss due to PLLA degradation increases with increasing immersion time. However, the rate of weight loss of pTi/PLLA during immersion decreases with increasing immersion time. Hydroxyapatite formation is observed on the surface of pTi/PLLA after immersion for ≥8 weeks. The decrease in the weight-loss rate may be caused by weight gain due to hydroxyapatite formation and/or the decrease in contact area with Hanks' solution caused by its formation on the surface of pTi/PLLA. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. The influence of polishing techniques on pre-polymerized CAD\\CAM acrylic resin denture bases.

    Science.gov (United States)

    Alammari, Manal Rahma

    2017-10-01

    Lately, computer-aided design and computer-aided manufacturing (CAD/CAM) has broadly been successfully employed in dentistry. The CAD/CAM systems have recently become commercially available for fabrication of complete dentures, and are considered as an alternative technique to conventionally processed acrylic resin bases. However, they have not yet been fully investigated. The purpose of this study was to inspect the effects of mechanical polishing and chemical polishing on the surface roughness (Ra) and contact angle (wettability) of heat-cured, auto-cured and CAD/CAM denture base acrylic resins. This study was conducted at the Advanced Dental Research Laboratory Center of King Abdulaziz University from March to June 2017. Three denture base materials were selected: heat cure poly-methylmethacrylate resin, thermoplastic (polyamide resin) and (CAD\\CAM) denture base resin. Sixty specimens were prepared and divided into three groups, twenty in each. Each group was divided according to the polishing techniques into (Mech P) and (Chem P), ten specimens in each; surface roughness and wettability were investigated. Data were analyzed by SPSS version 22, using one-way ANOVA and Pearson coefficient. One-way analysis of variance (ANOVA) and post hoc tests were used for comparing the surface roughness values between three groups which revealed a statistical significant difference between them (p 1 CAD\\CAM denture base material (group III) showed the least mean values (1.08±0.23, 1.39±0.31, Mech P and Chem P respectively). CAD/CAM showed the least contact angle in both polishing methods, which were statistically significant at 5% level (p=0.034 and pCAD\\CAM denture base resin with superior smooth surface compared to chemical polishing. Mechanical polishing is considered the best effective polishing technique. CAD/CAM denture base material should be considered as the material of choice for complete denture construction in the near future, especially for older dental

  20. Rational preparation of dibenzothiophene-imprinted polymers by surface imprinting technique combined with atom transfer radical polymerization

    International Nuclear Information System (INIS)

    Yang, Wenming; Liu, Lukuan; Zhou, Zhiping; Liu, Hong; Xie, Binze; Xu, Wanzhen

    2013-01-01

    A computational simulation method is introduced to simulate the dibenzothiophene-monomer pre-assembly system of molecular imprinted polymers. The interaction type and intensity between dibenzothiophene and monomer are discussed from the binding energy and spatial position distribution. The simulation and analysis results indicate that the amount of the function monomer is not the more the better in preparing molecular imprinted polymers. Based on the above results, a novel dibenzothiophene-imprinted polymers with the favorable specific adsorption effect was prepared by surface imprinting technique combined with atom transfer radical polymerization. This combined technologies are used for preparing a desulfurization adsorbent for the first time. Various measures were selected to characterize the structure and morphology of the prepared adsorbent. The characterization results show that the adsorbent has suitable features for further adsorption process. A series of static adsorption experiments were conducted to analyze its adsorption performance. The adsorption process follows Elovich model by the kinetic analysis and Sips equation by the isothermal analysis. The approach we described will provide another opportunity in the deep desulfurization field.

  1. Fabrication of hydroxyapatite-baghdadite nanocomposite scaffolds coated by PCL/Bioglass with polyurethane polymeric sponge technique

    Directory of Open Access Journals (Sweden)

    Ebrahim Karamian

    2017-07-01

    Full Text Available Objecttive (s: Silicate bioceramics like Baghdadite with chemical formula Ca3ZrSi2O9, has attracted the attention of researchers in biomedical field due to its remarkable in-vitro and in-vivo bioactivity and mechanical properties.Materials and Methods: Therefore, in the current study the baghdadite powder with Sol-Gel method was synthesized. Then, hydroxyapatite/Baghdadite (HA/Bagh scaffolds were prepared by the replacing the polyurethane polymeric sponge technique. Afterwhile, the ceramic scaffolds were sintered at 1150ºC for 3 h. The prepared scaffold was then coated by polycaprolactone/bioglass (PCL/BG polymer nanocomposite. Results: Bioactivity and biomineralization in the simulated body fluid (SBF revealed that the nanocomposite scaffolds coate with PCL/BG had significant bioactivity properties. The morophology and microstructure investigation of soaked samples in SBF indicate that bone-like apatite formed on the surfaces. Also, ion release in SBF containing the scaffolds was measured by inductively coupled plasma (ICP analysis. The nucleation positions of apatite crystals were areas with high silicon containing, Si+4 ion positions.Conclusion: The study indicates that scaffold containing 30 wt. % baghdadite had proper bioactivity behaviordue to its ability to form bone-like apatite on the surface of specimens.

  2. Comparison between two methods to evaluate temperature changes produced by composite light curing units and polymerization techniques.

    Science.gov (United States)

    Loureiro, F H F; Consani, S; Guiraldo, R D; Consani, R L X; Berger, S B; Carvalho, R V; Correr-Sobrinho, L; Sinhoreti, M A C

    2011-10-01

    This study evaluated the temperature change into the pulp chamber during the light curing of composite resin by direct (bovine tooth) and indirect (matrix) methods. Direct method: fifty standardized cavities (2x2x2 mm) were prepared in bovine incisors, which were randomly assigned to evaluation of the temperature changes in the pulp chamber. Indirect method: temperature changes were evaluated through a dentine slice of 1.0 mm thickness in a elastomer cubic mold (2x2x2 mm). Filtek Z250 composite resin (3M/ESPE) was photo-activated using three light curing units: quartz-tungsten-halogen (QTH) by continuous, soft-start or intermittent light modulations; light emitting diode (LED); and plasma arc-curing (PAC). Ten groups (N.=10) were established according to technique evaluation and photo-activation methods. All experiments were carried out in a controlled environment (37 °C and 50 ± 10% relative humidity). The temperature changes were recorded using a digital thermometer attached to a type-K thermocouple in contact with the dentin slice (indirect method) or in contact with the axial wall (dentin) of pulp chamber (direct method). The results were submitted to ANOVA and Tukey's test (α=0.05). Temperature changes were statistically higher for the matrix indirect method (2.56 ºC) than bovine teeth direct method (1.17ºC). The change temperature was statistically higher for the PAC (1.77 ºC) when compared to other photo-activation modes in bovine teeth direct method. The two methods of temperature evaluation were different, however indirect method detected the higher temperature increase. Higher energy density arising from the light curing units and polymerization techniques promoted higher temperature increase.

  3. Novas técnicas de reometria aplicadas a suspensões cerâmicas Novel rheometric techniques applied to ceramic suspensions

    Directory of Open Access Journals (Sweden)

    R. D. dos Anjos

    2005-06-01

    Full Text Available Suspensões cerâmicas com adequado comportamento reológico são imprescindíveis para a aplicação, adequação do processamento e otimização das propriedades finais dos produtos. No entanto, o uso de técnicas de reometria para análise de suspensões cerâmicas foi pouco explorado na literatura, quando comparado a outros sistemas, tais como polímeros fundidos. Desse modo, pretende-se demonstrar que o emprego de técnicas mais modernas de reometria permite uma nova compreensão desses materiais e das interações entre seus componentes. Neste trabalho foi estabelecida uma metodologia de análise para sistemas cerâmicos tendo como objeto de pesquisa uma suspensão de alumina e sol de sílica. Foi realizada uma série de medidas de viscosidade (eta, módulos de armazenamento (G' e de perda (G" e de força normal (Fn, cujos resultados servirão de base para estudos posteriores no mesmo sistema, visando aplicação em concretos refratários.Ceramic suspensions with suitable rheological properties are essential on application, process control and optimization of end products and properties. Nevertheless, the use of rheometric techniques to analyze such suspensions has been scarcely studied when compared to other systems, such as molten polymers. Therefore, in the present work, novel rheometric techniques will be presented which can allow a further understanding regarding these materials and the interaction among their components. A systematic study applying these techniques was established and the viscosity, storage modulus, loss modulus and normal force measurements were evaluated in a ceramic suspension containing alumina and silica sol. These results will be the fundaments for further studies, aiming their application on refractory castables.

  4. Ovarian Suspension With Adjustable Sutures: An Easy and Helpful Technique for Facilitating Laparoendoscopic Single-Site Gynecologic Surgery.

    Science.gov (United States)

    Chen, Kuo-Hu; Chen, Li-Ru; Seow, Kok-Min

    2015-01-01

    To describe a method of ovarian suspension with adjustable sutures (OSAS) for facilitating laparoendoscopic single-site gynecologic surgery (LESS) and to investigate the effect of OSAS on LESS. Prospective cohort study (Canadian Task Force classification: II-2). University teaching hospital. One hundred seventy-eight patients with benign 5- to 15-cm cystic ovarian tumors who underwent LESS with OSAS (suspension group, n = 90) and without OSAS (control group, n = 88). For patients who underwent OSAS (suspension group), 1 end of double-head straight needles with a polypropylene suture was inserted into the pelvic cavity through the abdominal skin to penetrate the cyst or ovarian parenchyma and puncture outside the abdominal skin. After cutting off the needles, both sides of the remaining suture were held together by a clamp, without knotting, so that the manipulator could "lift," "loosen," or "fix" the stitches to adjust the tension. The average time to create OSAS was 2.9 min. For the suspension and control groups, the average blood loss was 81.4 and 131.8 mL (p < .001), and the operative time was 42.0 and 61.3 min (p < .001), respectively. There were no significant differences in the incidence of complications (5.6% vs 9.1%; p = .365), but there were significant differences in conversions to standard non-single-site laparoscopy (5.6% vs 15.9%; p = .025) and laparotomy (1.1% vs 6.8%; p = .040). Logistic regression analysis revealed that the ratios of conversion to standard non-single-site laparoscopy (odds ratio [OR], 0.126; 95% confidence interval [CI], 0.311-0.508) and laparotomy (OR, 0.032; 95% CI, 0.002-0.479) were much lower in the suspension group; the risk of complications was comparable (OR, 0.346; 95% CI, 0.085-1.403). OSAS is an easy, safe, and feasible method that offers advantages during LESS. Although routine use of OSAS is not necessary, OSAS can be considered during LESS to facilitate the surgery. Copyright © 2015 AAGL. Published by Elsevier Inc. All

  5. Polymerization Using Phosphazene Bases

    KAUST Repository

    Zhao, Junpeng

    2015-09-01

    In the recent rise of metal-free polymerization techniques, organic phosphazene superbases have shown their remarkable strength as promoter/catalyst for the anionic polymerization of various types of monomers. Generally, the complexation of phosphazene base with the counterion (proton or lithium cation) significantly improves the nucleophilicity of the initiator/chain end resulting in highly enhanced polymerization rates, as compared with conventional metalbased initiating systems. In this chapter, the general features of phosphazenepromoted/catalyzed polymerizations and the applications in macromolecular engineering (synthesis of functionalized polymers, block copolymers, and macromolecular architectures) are discussed with challenges and perspectives being pointed out.

  6. A technique for simultaneous detection of individual vortex states of Laguerre-Gaussian beams transmitted through an aqueous suspension of microparticles

    Science.gov (United States)

    Khonina, S. N.; Karpeev, S. V.; Paranin, V. D.

    2018-06-01

    A technique for simultaneous detection of individual vortex states of the beams propagating in a randomly inhomogeneous medium is proposed. The developed optical system relies on the correlation method that is invariant to the beam wandering. The intensity distribution formed at the optical system output does not require digital processing. The proposed technique based on a multi-order phase diffractive optical element (DOE) is studied numerically and experimentally. The developed detection technique is used for the analysis of Laguerre-Gaussian vortex beams propagating under conditions of intense absorption, reflection, and scattering in transparent and opaque microparticles in aqueous suspensions. The performed experimental studies confirm the relevance of the vortex phase dependence of a laser beam under conditions of significant absorption, reflection, and scattering of the light.

  7. Density gradient multilayered polymerization (DGMP): a novel technique for creating multi-compartment, customizable scaffolds for tissue engineering.

    Science.gov (United States)

    Joshi-Barr, Shivanjali; Karpiak, Jerome V; Ner, Yogesh; Wen, Jessica H; Engler, Adam J; Almutairi, Adah

    2013-02-12

    Complex tissue culture matrices, in which types and concentrations of biological stimuli (e.g. growth factors, inhibitors, or small molecules) or matrix structure (e.g. composition, concentration, or stiffness of the matrix) vary over space, would enable a wide range of investigations concerning how these variables affect cell differentiation, migration, and other phenomena. The major challenge in creating layered matrices is maintaining the structural integrity of layer interfaces without diffusion of individual components from each layer. Current methodologies to achieve this include photopatterning, lithography, sequential functionalization5, freeze drying, microfluidics, or centrifugation, many of which require sophisticated instrumentation and technical skills. Others rely on sequential attachment of individual layers, which may lead to delamination of layers. DGMP overcomes these issues by using an inert density modifier such as iodixanol to create layers of varying densities. Since the density modifier can be mixed with any prepolymer or bioactive molecule, DGMP allows each scaffold layer to be customized. Simply varying the concentration of the density modifier prevents mixing of adjacent layers while they remain aqueous. Subsequent single step polymerization gives rise to a structurally continuous multilayered scaffold, in which each layer has distinct chemical and mechanical properties. The density modifier can be easily removed with sufficient rinsing without perturbation of the individual layers or their components. This technique is therefore well suited for creating hydrogels of various sizes, shapes, and materials. A protocol for fabricating a 2D-polyethylene glycol (PEG) gel, in which alternating layers incorporate RGDS-350, is outlined below. We use PEG because it is biocompatible and inert. RGDS, a cell adhesion peptide, is used to demonstrate spatial restriction of a biological cue, and the conjugation of a fluorophore (Alexa Fluor 350) enables

  8. PREDICTIVE CONTROL OF A BATCH POLYMERIZATION SYSTEM USING A FEEDFORWARD NEURAL NETWORK WITH ONLINE ADAPTATION BY GENETIC ALGORITHM

    OpenAIRE

    Cancelier, A.; Claumann, C. A.; Bolzan, A.; Machado, R. A. F.

    2016-01-01

    Abstract This study used a predictive controller based on an empirical nonlinear model comprising a three-layer feedforward neural network for temperature control of the suspension polymerization process. In addition to the offline training technique, an algorithm was also analyzed for online adaptation of its parameters. For the offline training, the network was statically trained and the genetic algorithm technique was used in combination with the least squares method. For online training, ...

  9. Particle interactions in concentrated suspensions

    International Nuclear Information System (INIS)

    Mondy, L.A.; Graham, A.L.; Abbott, J.R.; Brenner, H.

    1993-01-01

    An overview is presented of research that focuses on slow flows of suspensions in which colloidal and inertial effects are negligibly small. The authors describe nuclear magnetic resonance imaging experiments to quantitatively measure particle migration occurring in concentrated suspensions undergoing a flow with a nonuniform shear rate. These experiments address the issue of how the flow field affects the microstructure of suspensions. In order to understand the local viscosity in a suspension with such a flow-induced, spatially varying concentration, one must know how the viscosity of a homogeneous suspension depends on such variables as solids concentration and particle orientation. The authors suggest the technique of falling ball viscometry, using small balls, as a method to determine the effective viscosity of a suspension without affecting the original microstructure significantly. They also describe data from experiments in which the detailed fluctuations of a falling ball's velocity indicate the noncontinuum nature of the suspension and may lead to more insights into the effects of suspension microstructure on macroscopic properties. Finally, they briefly describe other experiments that can be performed in quiescent suspensions (in contrast to the use of conventional shear rotational viscometers) in order to learn more about boundary effects in concentrated suspensions

  10. Effect of Graphene Oxide on the Reaction Kinetics of Methyl Methacrylate In Situ Radical Polymerization via the Bulk or Solution Technique

    Directory of Open Access Journals (Sweden)

    Ioannis S. Tsagkalias

    2017-09-01

    Full Text Available The synthesis of nanocomposite materials based on poly(methyl methacrylate and graphene oxide (GO is presented using the in situ polymerization technique, starting from methyl methacrylate, graphite oxide, and an initiator, and carried out either with (solution or without (bulk in the presence of a suitable solvent. Reaction kinetics was followed gravimetrically and the appropriate characterization of the products took place using several experimental techniques. X-ray diffraction (XRD data showed that graphite oxide had been transformed to graphene oxide during polymerization, whereas FTIR spectra revealed no significant interactions between the polymer matrix and GO. It appears that during polymerization, the initiator efficiency was reduced by the presence of GO, resulting in a reduction of the reaction rate and a slight increase in the average molecular weight of the polymer formed, measured by gel permeation chromatography (GPC, along with an increase in the glass transition temperature obtained from differential scanning calorimetry (DSC. The presence of the solvent results in the suppression of the gel-effect in the reaction rate curves, the synthesis of polymers with lower average molecular weights and polydispersities of the Molecular Weight Distribution, and lower glass transition temperatures. Finally, from thermogravimetric analysis (TG, it was verified that the presence of GO slightly enhances the thermal stability of the nano-hybrids formed.

  11. Fully-polymeric pH sensor realized by means of a single-step soft embossing technique

    NARCIS (Netherlands)

    Fanzio, P.; Skolimowski, Maciej; Tanzi, Simone; Sasso, L.

    2017-01-01

    We present here an electrochemical sensor microsystem for the monitoring of pH. The all-polymeric device is comprised of a cyclic olefin copolymer substrate, a 200 nm-thin patterned layer of conductive polymer (PEDOT), and a 70 nm electropolymerized layer of a pH sensitive conductive polymer

  12. Evaluation of nano encapsulation techniques in different polymeric system for the delivery of anti-tuberculosis drugs (ATD)

    CSIR Research Space (South Africa)

    Swai, H

    2006-02-01

    Full Text Available In this study, isoniazid, one of the most potent anti-TB drugs, was successfully encapsulated in poly (D, L- lactide-co-glycolide) (PLG) and in alginate-chitosan polymeric systems using a double-emulsion method and a cation-induced gelation method...

  13. Combined Multi-criteria Evaluation Stage Technique as an Agro Waste Evaluation Indicator for Polymeric Composites: Date Palm Fibers as a Case Study

    Directory of Open Access Journals (Sweden)

    Faris M. AL-Oqla

    2014-06-01

    Full Text Available The final features of natural fiber composites (NFCs depend on the integrated characteristics of their constituents. In the industry today, natural agro waste fibers are evaluated using a limited number of criteria. In this work, a combined multi-criteria evaluation stage technique (CMCEST is introduced as a simple efficient systematic indicator to enhance evaluation of the available natural agro wastes for polymeric composites. In this proposed technique, criteria affecting the proper selection of natural agro waste fibers were combined and divided into sequence stages as follows: single-evaluation-criterion (SEC, combined-double-evaluation-criterion (CDEC, combined-triple-evaluation-criterion (CTEC, etc. These stages are based on combined physical, mechanical, and economic evaluation criteria and can be extended to several further stages to include other beneficial characteristics. The effectiveness of this technique was demonstrated by evaluating coir, date palm, jute, hemp, kenaf, and oil palm fibers simultaneously. This combined evaluation criteria can lead to more informative decisions regarding selection of the most suitable fiber type for polymeric composites. The CMCEST enhancements can reveal new potential fiber types through better evaluation schemes, help achieve clearer indications of the capabilities of available agro wastes to enhance composites, and determine proper ecological waste management practices. Utilizing the proposed technique, the date palm fiber type was found to be quite promising due to beneficial characteristics revealed in CTEC, which provides a reasonable, cheap, and eco-friendly alternative material suitable for different applications.

  14. Antitumor activity of docetaxel-loaded polymeric nanoparticles fabricated by Shirasu porous glass membrane-emulsification technique

    Directory of Open Access Journals (Sweden)

    Yu YN

    2013-07-01

    Full Text Available Yunni Yu,1,* Songwei Tan,1,2,* Shuang Zhao,1 Xiangting Zhuang,1 Qingle Song,1 Yuliang Wang,1 Qin Zhou,2,3 Zhiping Zhang1,2 1Tongji School of Pharmacy, 2National Engineering Research Center for Nanomedicine, 3College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, People’s Republic of China *These authors contributed equally to this work Abstract: Docetaxel (DTX has excellent efficiency against a wide spectrum of cancers. However, the current clinical formulation has limited its usage, as it causes some severe side effects. Various polymeric nanoparticles have thus been developed as alternative formulations of DTX, but they have been mostly fabricated on a laboratory scale. Previously, we synthesized a novel copolymer, poly(lactide-D-α-tocopheryl polyethylene glycol 1000 succinate (PLA-TPGS, and found that it exhibited great potential in drug delivery with improved properties. In this study, we applied the Shirasu porous glass (SPG membrane-emulsification technique to prepare the DTX-loaded PLA-TPGS nanoparticles on a pilot scale. The effect of several formulation variables on the DTX-loaded nanoparticle properties, including particle size, zeta potential, and drug-encapsulation efficiency, were investigated based on surfactant type and concentration in the aqueous phase, organic/aqueous phase volumetric ratio, membrane-pore size, transmembrane cycles, and operation pressure. The DTX-loaded nanoparticles were obtained with sizes of 306.8 ± 5.5 nm and 334.1 ± 2.7 nm (mean value ± standard deviation, and drug-encapsulation efficiency of 81.8% ± 4.5% and 64.5% ± 2.7% for PLA-TPGS and poly(lactic-co-glycolic acid (PLGA nanoparticles, respectively. In vivo pharmacokinetic study exhibited a significant advantage of PLA-TPGS nanoparticles over PLGA nanoparticles and Taxotere. Drug-loaded PLA-TPGS nanoparticles exhibited 1.78-, 6.34- and 3.35-fold higher values for area under the curve, half-life, and mean

  15. Synthesis of nanocrystalline Zn0.5Mn0.5Fe2O4 via in situ polymerization technique

    International Nuclear Information System (INIS)

    Liu Xianming; Fu Shaoyun

    2007-01-01

    Nanocrystalline Zn 0.5 Mn 0.5 Fe 2 O 4 was synthesized through the pyrolysis of polyacrylate salt precursors prepared via in situ polymerization of the metal salts and acrylic acid. The pyrolysis behavior of the polymeric precursors was studied by use of thermal analysis. The as-obtained product was characterized by powder X-ray diffraction (XRD), transmission electron microscope (TEM), electron diffraction (ED) pattern, scanning electron microscopy (SEM) and electron dispersive X-ray (EDX) analysis. The results revealed that the particle size is in the range of 15-25 nm for Zn-Mn ferrites with good crystallinity. Magnetic properties of the sample at 300 K were measured using a vibrating sample magnetometer, which showed that the sample exhibited characteristics of superparamagnetism

  16. Atom Transfer Radical Polymerization of Styrene in Presence of Mesoporous Silica Nanoparticles: Application of Reverse, Simultaneous Reverse and Normal Initiation Techniques

    Directory of Open Access Journals (Sweden)

    Khezrollah Khezri

    2014-04-01

    Full Text Available Atom transfer radical polymerization (ATRP of styrene in presence of mesoporous silica nanoparticles was carried out at 110 °C. Reverse atom transfer radical polymerization (RATRP and simultaneous reverse and normal initiation for atom transfer radical polymerization (SR&NI ATRP techniques were used as two appropriate introduced techniques for circumventing oxidation problems. Usage of metal catalyst in its higher oxidation state was the main feature of these initiation techniques in which deficiencies of normal ATRP were circumvented. Structure, surface area and pore diameter of synthesized mesoporous silica nanoparticles were evaluated using X–ray diffraction and nitrogen adsorption/desorption isotherm analysis. Average particle size was estimated around 600 nm by electron microscopy images. In addition, according to these images, nanoparticles revealed an appropriate size distribution. Particles size and their distribution were examined using scanning. Final monomer conversion was determined by using gas chromatography. The number and weight average molecular weights (Mn and Mw and polydispersity indexes (PDI were also evaluated by gel permeation chromatography. According to the results obtained, addition of mesoporous silica nanoparticles in both RATRP and SR&NI ATRP systems revealed similar effects: decrement of conversion and Mn and also increment of PDI values observed by increasing of mesoporous silica nanoparticles content. Improvement in thermal stability of the nanocomposites in comparison with neat polystyrene was demonstrated by thermogravimetric analysis (TGA. Moreover, in case of nanocomposites, thermal stability was obtained by higher loading of nanoparticles. A decrease in glass transition temperature by higher content of mesoporous silica nanoparticles has been demonstrated by differential scanning calorimetry analysis.

  17. Fabrication of mullite-bonded porous SiC ceramics from multilayer-coated SiC particles through sol-gel and in-situ polymerization techniques

    Science.gov (United States)

    Ebrahimpour, Omid

    In this work, mullite-bonded porous silicon carbide (SiC) ceramics were prepared via a reaction bonding technique with the assistance of a sol-gel technique or in-situ polymerization as well as a combination of these techniques. In a typical procedure, SiC particles were first coated by alumina using calcined powder and alumina sol via a sol-gel technique followed by drying and passing through a screen. Subsequently, they were coated with the desired amount of polyethylene via an in-situ polymerization technique in a slurry phase reactor using a Ziegler-Natta catalyst. Afterward, the coated powders were dried again and passed through a screen before being pressed into a rectangular mold to make a green body. During the heating process, the polyethylene was burnt out to form pores at a temperature of about 500°C. Increasing the temperature above 800°C led to the partial oxidation of SiC particles to silica. At higher temperatures (above 1400°C) derived silica reacted with alumina to form mullite, which bonds SiC particles together. The porous SiC specimens were characterized with various techniques. The first part of the project was devoted to investigating the oxidation of SiC particles using a Thermogravimetric analysis (TGA) apparatus. The effects of particle size (micro and nano) and oxidation temperature (910°C--1010°C) as well as the initial mass of SiC particles in TGA on the oxidation behaviour of SiC powders were evaluated. To illustrate the oxidation rate of SiC in the packed bed state, a new kinetic model, which takes into account all of the diffusion steps (bulk, inter and intra particle diffusion) and surface oxidation rate, was proposed. Furthermore, the oxidation of SiC particles was analyzed by the X-ray Diffraction (XRD) technique. The effect of different alumina sources (calcined Al2O 3, alumina sol or a combination of the two) on the mechanical, physical, and crystalline structure of mullite-bonded porous SiC ceramics was studied in the

  18. Administrative license suspension: Does length of suspension matter?

    Science.gov (United States)

    Fell, James C; Scherer, Michael

    2017-08-18

    Administrative license revocation (ALR) laws, which provide that the license of a driver with a blood alcohol concentration at or over the illegal limit is subject to an immediate suspension by the state department of motor vehicles, are an example of a traffic law in which the sanction rapidly follows the offense. The power of ALR laws has been attributed to how swiftly the sanction is applied, but does the length of suspension matter? Our objectives were to (a) determine the relationship of the ALR suspension length to the prevalence of drinking drivers relative to sober drivers in fatal crashes and (b) estimate the extent to which the relationship is associated to the general deterrent effect compared to the specific deterrent effect of the law. Data comparing the impact of ALR law implementation and ALR law suspension periods were analyzed using structural equation modeling techniques on the ratio of drinking drivers to nondrinking drivers in fatal crashes from the Fatality Analysis Reporting System (FARS). States with an ALR law with a short suspension period (1-30 days) had a significantly lower drinking driver ratio than states with no ALR law. States with a suspension period of 91-180 days had significantly lower ratios than states with shorter suspension periods, while the three states with suspension lengths of 181 days or longer had significantly lower ratios than states with shorter suspension periods. The implementation of any ALR law was associated with a 13.1% decrease in the drinking/nondrinking driver fatal crash ratio but only a 1.8% decrease in the intoxicated/nonintoxicated fatal crash ratio. The ALR laws and suspension lengths had a significant general deterrent effect, but no specific deterrent effect. States might want to keep (or adopt) ALR laws for their general deterrent effects and pursue alternatives for specific deterrent effects. States with short ALR suspension periods should consider lengthening them to 91 days or longer.

  19. Production and installation of equipments for radiation-induced graft polymerization in liquid phase and dipping techniques

    International Nuclear Information System (INIS)

    Seko, Noriaki; Kasai, Noboru; Tamada, Masao; Hasegawa, Shin; Katakai, Akio; Sugo, Takanobu

    2005-01-01

    Fibrous adsorbent which is synthesized by radiation induced graft polymerization on the trunk polymers such as polymer nonwoven fabrics and woven cloths exhibits an excellent selective adsorption against heavy metal ions and toxic gases at extremely low concentrations. Two equipments were installed to synthesize the metal-ion and gas adsorbents by means of the radiation-induced graft polymerization in the liquid phase and the dipping, respectively. In the reation chamber of the liquid phase reactor, the oxygen decreased to 100 ppm. The inside temperature was elevated at 80C. These characteristics satisfied the specification. The fabric transport can regulate the rate in the range from 1 to 10 m/min. The reactor for the dip grafting could reduce the inside oxygen to 100ppm and inside temperature could reach to 80C, also. The transport system is stable during the dip grafting reaction. The grafting of glycidyl methacrylate was carried out as a characteristic test. The degree of grafting was controlled in the range of 40-70%. The both equipments can graft the trunk polymer, 2000mm in maximum width and 1m in maximum diameter. This size is enough for confirmation practical scale synthesis. (author)

  20. Conformational and Structural Properties of High Functionality Dendrimer-like Star Polymers Synthesized from Living Polymerization Techniques; TOPICAL

    International Nuclear Information System (INIS)

    Pople, John A.

    2001-01-01

    The design, synthesis and solution properties of dendritic-linear hybrid macromolecules is described. The synthetic strategy employs living ring-opening polymerization in combination with selective and quantitative organic transformations for the preparation of new molecular architectures similar to classical star polymers and dendrimers. The polymers were constructed from high molecular weight poly(e-caprolactone) initiated from the surface hydroxyl groups of dendrimers derived from bis(hydroxymethyl) propionic acid (bis-MPA) in the presence of stannous 2-ethyl hexanoate (Sn(Oct)2). In this way, star and hyperstar poly(e-caprolactones) were elaborated depending on the generation of dendrimer employed. The ROP from these hydroxy groups was found to be a facile process leading to controlled molecular weight, low dispersity products (Mw/Mn) and lt; 1.15. In addition to the use of dendrimers as building blocks to star polymers, functional dendrons derived from bis-MPA were attached to chain ends of the star polymers, yielding structures that closely resemble that of the most advanced dendrimers. Measurements of the solution properties (hydrodynamic volume vs. molecular weight) on the dendritic-linear hybrids show a deviation from linearity, with a lower than expected hydrodynamic volume, analogous to the solution properties of dendrimers of high generation number. The onset of the deviation begins with the polymers initiated from the second generation dendrimer of bis-MPA and becomes more exaggerated with the higher generations. It was found that polymerization amplifies the nonlinear solution behavior of dendrimers. Small angle neutron scattering (SANS) measurements revealed that the radius of gyration scaled with arm functionality (f) as f 2/3, in accordance with the Daoud-Cotton model for many arm star polymer

  1. Optimal platform design using non-dominated sorting genetic algorithm II and technique for order of preference by similarity to ideal solution; application to automotive suspension system

    Science.gov (United States)

    Shojaeefard, Mohammad Hassan; Khalkhali, Abolfazl; Faghihian, Hamed; Dahmardeh, Masoud

    2018-03-01

    Unlike conventional approaches where optimization is performed on a unique component of a specific product, optimum design of a set of components for employing in a product family can cause significant reduction in costs. Increasing commonality and performance of the product platform simultaneously is a multi-objective optimization problem (MOP). Several optimization methods are reported to solve these MOPs. However, what is less discussed is how to find the trade-off points among the obtained non-dominated optimum points. This article investigates the optimal design of a product family using non-dominated sorting genetic algorithm II (NSGA-II) and proposes the employment of technique for order of preference by similarity to ideal solution (TOPSIS) method to find the trade-off points among the obtained non-dominated results while compromising all objective functions together. A case study for a family of suspension systems is presented, considering performance and commonality. The results indicate the effectiveness of the proposed method to obtain the trade-off points with the best possible performance while maximizing the common parts.

  2. Phosphazene-promoted anionic polymerization

    KAUST Repository

    Zhao, Junpeng

    2014-01-01

    In the recent surge of metal-free polymerization techniques, phosphazene bases have shown their remarkable potential as organic promoters/catalysts for the anionic polymerization of various types of monomers. By complexation with the counterion (e.g. proton or lithium cation), phosphazene base significantly improve the nucleophilicity of the initiator/chain-end resulting in rapid and usually controlled anionic/quasi-anionic polymerization. In this review, we will introduce the general mechanism, i.e. in situ activation (of initiating sites) and polymerization, and summarize the applications of such a mechanism on macromolecular engineering toward functionalized polymers, block copolymers and complex macromolecular architectures.

  3. Analysis of pushing exercises: muscle activity and spine load while contrasting techniques on stable surfaces with a labile suspension strap training system.

    Science.gov (United States)

    McGill, Stuart M; Cannon, Jordan; Andersen, Jordan T

    2014-01-01

    Labile surfaces in the form of suspension straps are increasingly being used as a tool in resistance training programs. Pushing is a common functional activity of daily living and inherently part of a well-rounded training program. This study examined pushing exercises performed on stable surfaces and unstable suspension straps, specifically muscle activation levels and spine loads were quantified together with the influence of employing technique coaching. There were several main questions that this study sought to answer: Which exercises challenged particular muscles? What was the magnitude of the resulting spine load? How did stable and unstable surfaces differ? Did coaching influence the results? Fourteen men were recruited as part of a convenience sample (mean age, 21.1 ± 2.0 years; height, 1.77 ± 0.06 m; mean weight, 74.6 ± 7.8 kg). Data were processed and input to a sophisticated and anatomically detailed 3D model that used muscle activity and body segment kinematics to estimate muscle force-in this way, the model was sensitive to the individuals choice of motor control for each task; muscle forces and linked segment joint loads were used to calculate spine loads. Exercises were performed using stable surfaces for hand/feet contact and repeated where possible with labile suspension straps. Speed of movement was standardized across participants with the use of a metronome for each exercise. There were gradations of muscle activity and spine load characteristics to every task. In general, the instability associated with the labile exercises required greater torso muscle activity than when performed on stable surfaces. Throughout the duration of an exercise, there was a range of compression; the TRX push-up ranged from 1,653 to 2,128.14 N, whereas the standard push-up had a range from 1,233.75 to 1,530.06 N. There was no significant effect of exercise on spine compression (F(4,60) = 0.86, p = 0.495). Interestingly, a standard push-up showed significantly

  4. Fully-Polymeric pH Sensor Realized by Means of a Single-Step Soft Embossing Technique

    Science.gov (United States)

    Fanzio, Paola; Chang, Chi-Tung; Skolimowski, Maciej; Tanzi, Simone; Sasso, Luigi

    2017-01-01

    We present here an electrochemical sensor microsystem for the monitoring of pH. The all-polymeric device is comprised of a cyclic olefin copolymer substrate, a 200 nm-thin patterned layer of conductive polymer (PEDOT), and a 70 nm electropolymerized layer of a pH sensitive conductive polymer (polyaniline). The patterning of the fluidic (microfluidic channels) and conductive (wiring and electrodes) functional elements was achieved with a single soft PDMS mold via a single embossing step process. A post-processing treatment with ethylene glycol assured the functional enhancement of the electrodes, as demonstrated via an electrical and electrochemical characterization. A surface modification of the electrodes was carried out, based on voltammetric electropolymerization, to obtain a thin layer of polyaniline. The mechanism for pH sensing is based on the redox reactions of the polyaniline layer caused by protonation. The sensing performance of the microsystem was finally validated by monitoring its potentiometric response upon exposure to a relevant range of pH. PMID:28531106

  5. Fully-Polymeric pH Sensor Realized by Means of a Single-Step Soft Embossing Technique

    Directory of Open Access Journals (Sweden)

    Paola Fanzio

    2017-05-01

    Full Text Available We present here an electrochemical sensor microsystem for the monitoring of pH. The all-polymeric device is comprised of a cyclic olefin copolymer substrate, a 200 nm-thin patterned layer of conductive polymer (PEDOT, and a 70 nm electropolymerized layer of a pH sensitive conductive polymer (polyaniline. The patterning of the fluidic (microfluidic channels and conductive (wiring and electrodes functional elements was achieved with a single soft PDMS mold via a single embossing step process. A post-processing treatment with ethylene glycol assured the functional enhancement of the electrodes, as demonstrated via an electrical and electrochemical characterization. A surface modification of the electrodes was carried out, based on voltammetric electropolymerization, to obtain a thin layer of polyaniline. The mechanism for pH sensing is based on the redox reactions of the polyaniline layer caused by protonation. The sensing performance of the microsystem was finally validated by monitoring its potentiometric response upon exposure to a relevant range of pH.

  6. Fully-Polymeric pH Sensor Realized by Means of a Single-Step Soft Embossing Technique.

    Science.gov (United States)

    Fanzio, Paola; Chang, Chi-Tung; Skolimowski, Maciej; Tanzi, Simone; Sasso, Luigi

    2017-05-20

    We present here an electrochemical sensor microsystem for the monitoring of pH. The all-polymeric device is comprised of a cyclic olefin copolymer substrate, a 200 nm-thin patterned layer of conductive polymer (PEDOT), and a 70 nm electropolymerized layer of a pH sensitive conductive polymer (polyaniline). The patterning of the fluidic (microfluidic channels) and conductive (wiring and electrodes) functional elements was achieved with a single soft PDMS mold via a single embossing step process. A post-processing treatment with ethylene glycol assured the functional enhancement of the electrodes, as demonstrated via an electrical and electrochemical characterization. A surface modification of the electrodes was carried out, based on voltammetric electropolymerization, to obtain a thin layer of polyaniline. The mechanism for pH sensing is based on the redox reactions of the polyaniline layer caused by protonation. The sensing performance of the microsystem was finally validated by monitoring its potentiometric response upon exposure to a relevant range of pH.

  7. Qualitative analysis of controlled release ciprofloxacin/carbopol 934 mucoadhesive suspension

    Directory of Open Access Journals (Sweden)

    Subhashree Sahoo

    2011-01-01

    Full Text Available Mucoadhesive polymeric (carbopol 934 suspension of ciprofloxacin was prepared by ultrasonication and optimized with the aim of developing an oral controlled release gastro-retentive dosage form. The qualitative analysis of the formulation was performed by fourier transform infrared spectroscopy (FTIR, Raman spectroscopy, X-ray powder diffraction (XRD, and scanning electron microscopy (SEM analyses. FTIR (400 cm-1 to 4000 cm-1 region and Raman (140 to 2400 cm-1 region Spectroscopic studies were carried out and the spectra were used for interpretation. XRD data of pure drug, polymer and the formulation were obtained using a powder diffractometer scanned from a Bragg′s angle (2q of 10° to 70°. The dispersion of the particle was observed using SEM techniques. The particle size distribution and aspect ratio of particles in the polymeric suspension were obtained from SEM image analysis. The results from FTIR and Raman spectroscopic analyses suggested that, in formulation, the carboxylic groups of ciprofloxacin and hydroxyl groups of C934 undergo a chemical interaction leading to esterification and hydrogen bonding. The XRD data suggested that the retention of crystalline nature of ciprofloxacin in the formulation would lead to increase in stability and drug loading; decrease in solubility; and delay in release of the drug from polymeric suspension with better bioavailability and penetration capacity. The SEM image analysis indicated that, in the formulation maximum particles were having aspect ratio from 2 to 4 and standard deviation was very less which provided supporting evidences for homogeneous, uniformly dispersed, stable controlled release ciprofloxacin suspension which would be pharmaceutically acceptable.

  8. Elektroaktive polymerer

    DEFF Research Database (Denmark)

    West, K.

    Traditionelt tænker vi på polymerer (plastik) som elektrisk isolerende materialer - det som er udenpå ledningerne. I dag kender vi imidlertid også polymerer med intrinsisk elektrisk ledningsevne, og plast er på vej ind i anvendelser, der tidligereudelukkende var baseret på metaller og uorganiske...... halvledere. Hertil kommer, at en del af de ledende polymerer kan stimuleres til at skifte mellem en ledende og en halvledende tilstand, hvorved de ændret både form og farve. I foredraget gives der enrække eksempler på anvendelse af polymerer som elektriske komponenter - rækkende fra polymer elektronik over...

  9. Enhancement of dissolution and oral bioavailability of lacidipine via pluronic P123/F127 mixed polymeric micelles: formulation, optimization using central composite design and in vivo bioavailability study.

    Science.gov (United States)

    Fares, Ahmed R; ElMeshad, Aliaa N; Kassem, Mohamed A A

    2018-11-01

    This study aims at preparing and optimizing lacidipine (LCDP) polymeric micelles using thin film hydration technique in order to overcome LCDP solubility-limited oral bioavailability. A two-factor three-level central composite face-centered design (CCFD) was employed to optimize the formulation variables to obtain LCDP polymeric micelles of high entrapment efficiency and small and uniform particle size (PS). Formulation variables were: Pluronic to drug ratio (A) and Pluronic P123 percentage (B). LCDP polymeric micelles were assessed for entrapment efficiency (EE%), PS and polydispersity index (PDI). The formula with the highest desirability (0.959) was chosen as the optimized formula. The values of the formulation variables (A and B) in the optimized polymeric micelles formula were 45% and 80%, respectively. Optimum LCDP polymeric micelles had entrapment efficiency of 99.23%, PS of 21.08 nm and PDI of 0.11. Optimum LCDP polymeric micelles formula was physically characterized using transmission electron microscopy. LCDP polymeric micelles showed saturation solubility approximately 450 times that of raw LCDP in addition to significantly enhanced dissolution rate. Bioavailability study of optimum LCDP polymeric micelles formula in rabbits revealed a 6.85-fold increase in LCDP bioavailability compared to LCDP oral suspension.

  10. The polymeric nanofilm of triazinedithiolsilane fabricated by self-assembled technique on copper surface. Part 2: Characterization of composition and morphology

    International Nuclear Information System (INIS)

    Wang, Yabin; Liu, Zhong; Huang, Yudong; Qi, Yutai

    2015-01-01

    Highlights: • The chemical reactions between copper and triazinedithiolsilane were revealed. • The structure of triazinedithiolsilane's polymeric nanofilm was demonstrated. • The morphology and microstructure of the polymeric nanofilm was observed. - Abstract: In the first part, a novel design route for metal protection against corrosion was proposed, and a class of triazinedithiolsilane compounds was conceived as protector for copper. The protective capability of the polymeric nanofilm, fabricated by self-assembling one representative (abbreviated as TESPA) of triazinedithiolsilane compounds onto copper surface, has been investigated and evaluated by electrochemical tests. The results show that the polymeric nanofilm significantly inhibits copper corrosion. This study, on the one hand, concentrates on the chemical composition of the TESPA polymeric nanofilm by means of X-ray photoelectron spectroscopy (XPS). The XPS results reveal that the chemical bonds between copper and TESPA monomers, three dimensional disulfide units and siloxane networks are responsible for the satisfactory protection of TESPA polymeric nanofilm against copper corrosion. On the other hand, scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS) are utilized to reveal the morphology and the uniformity of the TESPA polymeric nanofilm. The SEM-EDS results demonstrate that the copper surfaces are uniformly covered with TESPA self-assembled monolayer and the polymeric nanofilm. The TESPA-covered copper surfaces turn out to be smoother than that of the bare copper surface.

  11. Functionalization and Polymerization on the CNT Surfaces

    KAUST Repository

    Albuerne, Julio

    2013-07-01

    In this review we focus on the current status of using carbon nanotube (CNT) as a filler for polymer nanocomposites. Starting with the historical background of CNT, its distinct properties and the surface functionalization of the nanotube, the three different surface polymerization techniques, namely grafting "from", "to" and "through/in between" were discussed. Wider focus has been given on "grafting from" surface initiated polymerizations, including atom transfer radical polymerization (ATRP), reversible addition fragmentation chain-transfer (RAFT) Polymerization, nitroxide mediated polymerization (NMP), ring opening polymerization (ROP) and other miscellaneous polymerization methods. The grafting "to" and "through / in between" also discussed and compared with grafting from polymerization. The merits and shortcomings of all three grafting methods were discussed and the bottleneck issue in grafting from method has been highlighted. Furthermore the current and potential future industrial applications were deliberated. Finally the toxicity issue of CNTs in the final product has been reviewed with the limited available literature knowledge. © 2013 Bentham Science Publishers.

  12. Synthesis and polymerization of vinyl triazolium ionic liquids

    Science.gov (United States)

    Luebke, David; Nulwala, Hunaid; Matyjaszewski, Krzysztof; Adzima, Brian

    2018-05-15

    Herein, we describe polymerized ionic liquids, demonstrate the synthesis of polymerized ionic liquids, and demonstrate the polymerization of triazolium monomers. One embodiment shows the polymeriazation of the triazolium monomers with bis(trifluoromethanesulfonyl)imide anions. In another embodiment we show the feasibility of copolymerizing with commodity monomers such as styrene using free radical polymerization techniques.

  13. Click polymerization for the synthesis of reduction-responsive polymeric prodrug

    Science.gov (United States)

    Zhang, Xiaojin; Wang, Hongquan; Dai, Yu

    2018-05-01

    Click polymerization is a powerful polymerization technique for the construction of new macromolecules with well-defined structures and multifaceted functionalities. Here, we synthesize reduction-responsive polymeric prodrug PEG- b-(PSS- g-MTX)- b-PEG containing disulfide bonds and pendant methotrexate (MTX) via two-step click polymerization followed by conjugating MTX to pendant hydroxyl. MTX content in polymeric prodrug is 13.5%. Polymeric prodrug is able to form polymeric micelles by self-assembly in aqueous solution. Polymeric micelles are spherical nanoparticles with tens of nanometers in size. Of note, polymeric micelles are reduction-responsive due to disulfide bonds in the backbone of PEG- b-(PSS- g-MTX)- b-PEG and could release pendant drugs in the presence of the reducing agents such as dl-dithiothreitol (DTT).

  14. Design of colon targeting drug delivery systems using natural polymeric carriers and their evaluation by gamma scintigraphy technique

    International Nuclear Information System (INIS)

    Soni, P.S.; Sawarkar, S.P.; Deshpande, S.G.; Bajaj, A.N.

    2004-01-01

    Of late, there has been a great awareness in the concept of drug targeting and delivery to a specific site (organ, tissue or cell) in the body to maximize therapeutic effect and reduce toxicity. The various approaches of site-specific drug delivery are implantable pumps, adhesive patches impregnated with drugs, vesicle enclosed drugs and drug carriers. Colonic drug delivery is intended for local and systemic treatment in the diseases of colon like inflammatory bowel conditions. Several approaches using viz. pro-drugs, biodegradable polymers and pH sensitive polymer coatings have been used to achieve colonic delivery. Natural polysaccarides like guar gum and pectin are promising candidates because they are susceptible to degradation by colonic bacteria and thus can release the entrapped drug in the colonic region. These indigenous natural polymers are cheaply and readily available. They comprise of polygalactouronic acid and refractory to host enzymes present in the upper gastrointestinal tract and are degraded by the enzymes produced by the colonic microflora. They were evaluated as a colonic carrier using 5-amino salicylic acid (5-ASA) as a model drug. After successful in vitro testing, gamma scintigraphy technique was used to assess in-vivo behavior of the colon specific drug delivery after a coat of Guar gum and Pectin

  15. Improvement of Dispersion and Color Effect of Organic Pigments in Polymeric Films via Microencapsulation by the Miniemulsion Technique

    Directory of Open Access Journals (Sweden)

    Dongming Qi

    2013-01-01

    Full Text Available Three primary pigment/poly(n-butyl acrylate-co-styrene (P(BA+St nanocomposites were prepared via encapsulation of the corresponding organic pigments via the miniemulsion technique. The resulting latexes of the P(BA+St/pigment nanocomposites were filmed in a PTFE mould or printed onto cotton fabric. The morphology of the P(BA+St/pigment nanocomposites and the dispersion of pigment particles in the latex film and on the printed fabric surface, as well as the adhesion between pigment and adhesive film, were evaluated by transmission electron microscopy (TEM, field emission scanning electron microscopy (FESEM, 3D digital microscope system (3D-POM, and printing results tests. Attributing to the preprotection of adhesive polymer shell, the self-adhesive P(BA+St/pigment nanocomposites were homogeneously and firmly dispersed both in the thin latex film and in the adhesive layer on the fiber surface. As a result, the color strength, color fastness, and handle of the fabrics printed by the P(BA+St/pigment nanocomposites latex were significantly improved, compared to the fabrics printed by the conventional pigment blended latex.

  16. Cranioplasty with individual carbon fibre reinforced polymere (CFRP) medical grade implants based on CAD/CAM technique.

    Science.gov (United States)

    Saringer, W; Nöbauer-Huhmann, I; Knosp, E

    2002-11-01

    The authors present a new method for the reconstruction of large or complex-formed cranial bone defects using prefabricated, computer-generated, individual CFRP (carbon fibre reinforced plastics) medical grade implants. CFRP is a composite material containing carbon fibres embedded in an epoxy resin matrix. It is radiolucent, heat-resistant, extremely strong and light (its weight is 20% that of steel), has a modulus of elasticity close to that of bone, and an established biocompatibility. The utilisation of a CAD/CAM (computer aided design/computer aided manufacture) technique based on digitised computed tomography (CT) data, with stereolithographic modelling as intermediate step, enabled the production of individual, prefabricated CFRP medical grade implants with an arithmetical maximum aberration in extension of less than +/-0.25 mm. Between 1995 and February 2002, 29 patients (15 men and 14 women; mean age, 39.9 years; range, 16 to 67 years) underwent cranioplasty with CFRP medical grade implants at the neurosurgical department of the University of Vienna. Twenty-four patients were repaired secondarily (delayed cranioplasty) while 5 were repaired immediately following craniectomy (single stage cranioplasty). All cases were assessed for the accuracy of the intra-operative fit of the implant, restoration of the natural skull contour and aesthetics and adverse symptoms. The intra-operative fit was excellent in 93.1% and good in 6.9% of the implants. In two cases minor adjustments of the bony margin of the defect were required. The operating time for insertion ranged from 16 to 38 minutes, median 21 minutes. Postoperatively, 86.2% of the patients graded the restoration of their natural skull shape and symmetry as excellent while 13.8% termed it good. In one patient a non-space occupying subdural hygroma was found at the follow-up, but required no intervention. Two patients experienced atrophy of the frontal portion of the temporal muscle while one patient had a

  17. EDITORIAL: Colloidal suspensions Colloidal suspensions

    Science.gov (United States)

    Petukhov, Andrei; Kegel, Willem; van Duijneveldt, Jeroen

    2011-05-01

    Special issue in honour of Henk Lekkerkerker's 65th birthday Professor Henk N W Lekkerkerker is a world-leading authority in the field of experimental and theoretical soft condensed matter. On the occasion of his 65th birthday in the summer of 2011, this special issue celebrates his many contributions to science. Henk Lekkerkerker obtained his undergraduate degree in chemistry at the University of Utrecht (1968) and moved to Calgary where he received his PhD in 1971. He moved to Brussels as a NATO fellow at the Université Libre de Bruxelles and was appointed to an assistant professorship (1974), an associate professorship (1977) and a full professorship (1980) in physical chemistry at the Vrije Universiteit Brussel. In 1985 he returned to The Netherlands to take up a professorship at the Van 't Hoff Laboratory, where he has been ever since. He has received a series of awards during his career, including the Onsager Medal (1999) of the University of Trondheim, the Bakhuys Roozeboom Gold Medal (2003) of the Royal Dutch Academy of Arts and Sciences (KNAW), the ECIS-Rhodia European Colloid and Interface Prize (2003), and the Liquid Matter Prize of the European Physical Society (2008). He was elected a member of KNAW in 1996, was awarded an Academy Chair position in 2005, and has held several visiting lectureships. Henk's work focuses on phase transitions in soft condensed matter, and he has made seminal contributions to both the theoretical and experimental aspects of this field. Here we highlight three major themes running through his work, and a few selected publications. So-called depletion interactions may lead to phase separation in colloid-polymer mixtures, and Henk realised that the partitioning of polymer needs to be taken into account to describe the phase behaviour correctly [1]. Colloidal suspensions can be used as model fluids, with the time- and length-scales involved leading to novel opportunities, notably the direct observation of capillary waves at a

  18. Processing of high performance composites based on peek by aqueous suspension prepregging

    Directory of Open Access Journals (Sweden)

    Liliana Burakowski Nohara

    2010-06-01

    Full Text Available The use of polyamic acid (PAA precursor as interphase in polymer composites is one of the many applications of polyimides (PIs. In this work, composites based on poly(ether-ether-ketone (PEEK and carbon fibers were prepared using two manufacturing techniques for thermoplastic composites: hot compression molding, and aqueous polymeric suspension prepregging using PIs as interphase. Two PAAs were synthesized and used as interphases: 3,3'-4,4'-benzophenonetetracarboxylic dianhydride/oxydianiline (BTDA/ODA and pyromellitic dianhydride/oxydianiline (PMDA/ODA. The PAA/PI systems were analyzed by differential scanning calorimetry (DSC, thermogravimetry (TGA, Fourier transform infrared spectroscopy (FTIR and nuclear magnetic resonance (NMR. Results from these analyses confirmed the synthesis of these compounds. Aqueous polymeric suspension prepregging was more efficient than hot compression molding when the PMDA/ODA PAA/PI interphase was used; also, the interlaminar shear strength of composites produced using this technique was 14.5% higher than the one produced using hot compression molding.

  19. The polymeric nanofilm of triazinedithiolsilane fabricated by self-assembled technique on copper surface. Part 2: Characterization of composition and morphology

    Science.gov (United States)

    Wang, Yabin; Liu, Zhong; Huang, Yudong; Qi, Yutai

    2015-11-01

    In the first part, a novel design route for metal protection against corrosion was proposed, and a class of triazinedithiolsilane compounds was conceived as protector for copper. The protective capability of the polymeric nanofilm, fabricated by self-assembling one representative (abbreviated as TESPA) of triazinedithiolsilane compounds onto copper surface, has been investigated and evaluated by electrochemical tests. The results show that the polymeric nanofilm significantly inhibits copper corrosion. This study, on the one hand, concentrates on the chemical composition of the TESPA polymeric nanofilm by means of X-ray photoelectron spectroscopy (XPS). The XPS results reveal that the chemical bonds between copper and TESPA monomers, three dimensional disulfide units and siloxane networks are responsible for the satisfactory protection of TESPA polymeric nanofilm against copper corrosion. On the other hand, scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS) are utilized to reveal the morphology and the uniformity of the TESPA polymeric nanofilm. The SEM-EDS results demonstrate that the copper surfaces are uniformly covered with TESPA self-assembled monolayer and the polymeric nanofilm. The TESPA-covered copper surfaces turn out to be smoother than that of the bare copper surface.

  20. Interfacial Polymerization of Polyaniline Nanofibers Grafted to Au Surfaces

    National Research Council Canada - National Science Library

    Sawall, D

    2004-01-01

    .... The in-situ polymerization technique of these PANI nanofibers in the presence of sulfonated polystyrene allowed for the growth of PANI 2-D nanostructures embedded in the polymerized sulfonated host...

  1. Chelating polymeric membranes

    KAUST Repository

    Peinemann, Klaus-Viktor; Villalobos Vazquez de la Parra, Luis Francisco; Hilke, Roland

    2015-01-01

    microporous chelating polymeric membrane. Embodiments include, but are not limited to, microporous chelating polymeric membranes, device comprising the membranes, and methods of using and making the same.

  2. Comparison of the Emulsion Mixing and In Situ Polymerization Techniques for Synthesis of Water- Borne Reduced Graphene Oxide/Polymer Composites: Advantages and Drawbacks

    Czech Academy of Sciences Publication Activity Database

    Arzac, A.; Leal, G.L.; Fajgar, Radek; Tomovska, R.

    2014-01-01

    Roč. 31, č. 1 (2014), s. 143-151 ISSN 0934-0866 Grant - others:BG(ES) NanoIker 2012–2013; NATO(US) SfP 984399 Institutional support: RVO:67985858 Keywords : polymerization * composite films * latex blends Subject RIV: CA - Inorganic Chemistry Impact factor: 3.081, year: 2014

  3. The influence of the PDMS technique in the study of the induced modifications of polymers used in nuclear environment; Apport de la technique PDMS a l`etude des modifications induites dans des polymeres utilises en ambiance nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    Nsouli, B [Lyon-1 Univ., 69 - Villeurbanne (France). Inst. de Physique Nucleaire

    1995-07-20

    The PDMS technique (Particle Induced Desorption Mass Spectrometry) combined with a TOF detection (Time of Flight) is the main tool used in this study of polymer degradation in nuclear environment. Ar{sup 3+} ions with a 9 MeV energy have been used to induce the secondary ion emission, and the study was devoted to two stresses typical of this type of environment. The first part of the work concerned with the structural modifications induced by gamma irradiation on ion exchange resin, used for nuclear effluents reprocessing, namely the poly(4-vinylpyridine), or P-4PV. For such a material, the negative fragment emission is particularly sensitive to structural modifications. Difficult physical measurements in such an insoluble and infusible material (IR, UV - Vis, EPR, TGA, dielectric measurements) became consistent after the degradation mechanisms were elucidated. These effects, interpreted in terms of scissions and recombinations, enabled us to explicit different modes of energy deposition, and shed light on some discrepancies between SIMS and PDMS. The second part of the study is devoted to the thermal ageing of an elastomer, used in fabrication of valve gaskets submitted to high temperatures. First of all, we studied the constituents of the polymeric material, i. e. copolymer, homo polymers, and also additives. This last component proved useful to analyze, as a superficial lubricant layer can mask the conformational rearrangements which seem to occur after few hours of thermal treatment (PE blocks are prevailing at the surface). Here too, the PDMS information is important to account for static SIMS and ESCA results, as its probed layer thickness lies in-between. (author) 187 refs.

  4. Suspension trauma; Le traumatisme de suspension

    Energy Technology Data Exchange (ETDEWEB)

    Trudel, S. [Le Centre de sante et de services sociaux du rocher Perce, Chandler, PQ (Canada)

    2010-07-01

    This presentation discussed the precautions that should be taken to avoid falls from wind turbines or transmission towers. Suspension trauma was explained by a medical doctor in terms of physiology and the body's normal circulation and the elements that disturb normal physiology when in suspension. The trauma occurs following a fall, which carries the risk of 1or more disorders, such as massive hemorrhage, high cardiac pulse, and constriction of blood vessels. Nausea, vertigo, cardiac arrhythmia and sweating occur 15 to 20 minutes following the fall. The presentation emphasized the importance of having qualified personnel at the site and wearing proper harnesses and equipment that supports the neck. figs.

  5. Development of a polymeric matrix for composite material produced by the filament winding technique; Desenvolvimento de matriz polimerica visando a producao de material composito atraves da tecnica de enrolamento filamentar

    Energy Technology Data Exchange (ETDEWEB)

    Sobrinho, Ledjane Lima; Ferreira, Marisilvia; Bastian, Fernando Luiz [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia

    2005-07-01

    The study of the resin for composite materials to be produced by the filament winding technique is very important, since the good applicability of the technique is in part function of the characteristics of the resin. The objective of this work is the development of a polymeric matrix using vinyl ester resin for composite to be produced by the filament winding technique. Therefore, vinyl ester resin systems developed from Derakane 411-350 by varying the percentage of cure agent and activator. The system which presented the best behavior in tension (Yong's modulus 2,42 GPa, tensile strength = 47,67 MPa, elongation = 7,31 % and fracture toughness 2,67 J), adequate gel time and exothermic peak for the manufacture process was submitted to hygrothermal aging by immersion in water at 60 deg C for a maximum period of 64 days. (author)

  6. Radiation Induced Polymerization of Pyrrole

    International Nuclear Information System (INIS)

    Sarada Idris; Ratnam, C.T.; Ahmad Ashrif Abu Bakar

    2016-01-01

    We demonstrate the polymerization of pyrrole by gamma irradiation. The pyrrole films were exposed to gamma ray from cobalt 60 source at doses ranging from 0 to 150 kGy. The films were subjected to structural and morphological analyses by using FTIR, SEM and AFM techniques. Similar studies were also made on pristine pyrrole film which serve as control. Results revealed that pyrrole has been successfully polymerized through irradiation induced reactions. The SEM images depicted the formation of cauliflower shape upon gamma irradiation. The structural changes of pyrrole also evidenced by FTIR spectra. Surface topography and roughness of pyrrole before and after gamma irradiation found to show significant differences. (author)

  7. Chain Dynamics in Magnetorheological Suspensions

    Science.gov (United States)

    Gast, A. P.; Furst, E. M.

    1999-01-01

    fluctuating chains of dipolar particles. Resolving this issue would contribute greatly to the understanding of these interesting and important materials. We have begun to test the predictions of the HT model by both examining the dynamics of individual chains and by measuring the forces between dipolar chains directly to accurately and quantitatively assess the interactions that they experience. To do so, we employ optical trapping techniques and video-microscopy to manipulate and observe our samples on the microscopic level. With these techniques, it is possible to observe chains that are fluctuating freely in three-dimensions, independent of interfacial effects. More importantly, we are able to controllably observe the interactions of two chains at various separations to measure the force-distance profile. The techniques also allow us to study the mechanical properties of individual chains and chain clusters. Our work to this point has focused on reversibly-formed dipolar chains due to field induced dipoles where the combination of this chaining, the dipolar forces, and the hydrodynamic interactions that dictate the rheology of the suspensions. One can envision, however, many situations where optical, electronic, or rheological behavior may be optimized with magneto-responsive anisotropic particles. Chains of polarizable particles may have the best properties as they can coil and flex in the absence of a field and stiffen and orient when a field is applied. We have recently demonstrated a synthesis of stable, permanent paramagnetic chains by both covalently and physically linking paramagnetic colloidal particles. The method employed allows us to create monodisperse chains of controlled length. We observed the stability, field-alignment, and rigidity of this new class of materials. The chains may exhibit unique rheological properties in an applied magnetic field over isotropic suspensions of paramagnetic particles. They are also useful rheological models as bead

  8. Direct determination of the rate constant of propagation by pseudo-stationary polymerization technique: screening investigation for the (implicit) penultimate effect

    International Nuclear Information System (INIS)

    Schnoll-Bitai, I.; Friedrich Olaj, O.; Liu Song Yu

    1999-01-01

    The systems styrene-p-methylstyrene, styrene-p-chlorostyrene, methyl methacrylate-p-methylstyrene and methyl methacrylate-p-chlorostyrene were polymerized under pseudo-stationary conditions (rotating sector or pulsed laser) at 25 degree C, 40 degree C and 50 degree C. The respective molecular weight distributions measured by GPC were analysed in order to derive directly the phenomenological rate constant of propagation, κ sub ρ. Copolymer compositions as a function of monomer feed could be described by the terminal model, whereas the kinetic results could only be interpreted in terms of the restricted penultimate model

  9. Synthesis and silica coating of calcia-doped ceria/plate-like titanate (K0.8Li0.27Ti1.73O4) nanocomposite by seeded polymerization technique

    International Nuclear Information System (INIS)

    El-Toni, Ahmed Mohamed; Yin, Shu; Sato, Tsugio

    2007-01-01

    Calcia-doped ceria is of potential interest as an ultraviolet (UV) radiation blocking material in personal care products because of the excellent UV light absorption property and low catalytic ability for the oxidation of organic materials superior to undoped ceria. In order to reduce the oxidation catalytic activity further, calcia-doped ceria was coated with amorphous silica by means of seeded polymerization technique. Generally, nanoparticles of inorganic materials do not provide a good coverage for human skin because of the agglomeration of the particles. The plate-like particles are required to enhance the coverage ability of inorganic materials. This can be accomplished by synthesis of calcia-doped ceria/plate-like potassium lithium titanate (K 0.8 Li 0.27 Ti 1.73 O 4 ) nanocomposite with subsequent silica coating to control catalytic activity of calcia-doped ceria. Calcia-doped ceria/plate-like potassium lithium titanate nanocomposite was prepared by soft chemical method followed by silica coating via seeded polymerization technique. Silica coated calcia-doped ceria/plate-like potassium lithium titanate nanocomposite was characterized by X-ray diffraction, SEM, TEM, XPS and FT-IR

  10. "Click" i polymerer 2

    DEFF Research Database (Denmark)

    Hvilsted, Søren

    2012-01-01

    "Click"-reaktioner til fremstilling af ledende polymerer med funktionelle håndtag og bipolymermaterialer......"Click"-reaktioner til fremstilling af ledende polymerer med funktionelle håndtag og bipolymermaterialer...

  11. Conducting Polymeric Materials

    DEFF Research Database (Denmark)

    Hvilsted, Søren

    2016-01-01

    The overall objective of this collection is to provide the most recent developments within the various areas of conducting polymeric materials. The conductivity of polymeric materials is caused by electrically charged particles, ions, protons and electrons. Materials in which electrons...

  12. Nanoparticles from a controlled polymerization process

    International Nuclear Information System (INIS)

    Tirumala, V.R.; Caneba, G.T.; Dar, Y.; Wang, H.-H.; Mancini, D.C.

    2003-01-01

    Free-radical retrograde precipitation polymerization process in the past has shown excellent control characteristics over reaction rate, molecular weight, and in the entrapment of live radicals for the generation of block copolymers. The same principle has now been extended to study the reaction confinement to a nanoscale region. Nanosized polymer particles have been reported to form from block copolymers, conventional precipitation polymerization methods, or through emulsion polymerization approaches. In this work, we present a new method of generating nanosized polymer particles by polymerizing the monomer in an environment that precipitates the polymer above the lower critical solution temperature. The nanoparticles have been characterized by both tapping-mode atomic force microscopy observations and in situ synchrotron time-resolved small-angle X-ray scattering analysis. The results from both the techniques showed the formation of nanoparticles in the size range of 15-30 nm, directly from the polymerization process.

  13. Rheology of organoclay suspension

    CSIR Research Space (South Africa)

    Hato, MJ

    2011-05-01

    Full Text Available The authors have studied the rheological properties of clay suspensions in silicone oil, where clay surfaces were modified with three different types of surfactants. Dynamic oscillation measurements showed a plateau-like behavior for all...

  14. Hydropneumatic suspension systems

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Wolfgang

    2011-07-01

    Hydropneumatic suspensions systems combine the excellent properties of gas springs with the favourable damping properties of hydraulic fluids. The advantages of these systems are particularly appropriate for automotive applications, such as passenger cars, trucks and agricultural equipment. In this book, Dr. Bauer provides an extensive overview of hydropneumatic suspension systems. Starting with a comparison of different types of suspension systems, the author subsequently describes the theoretical background associated with spring and damping characteristics of hydropneumatic systems and furthermore explains the design of the most important system components. Additionally he gives an overview of level control systems and various special functions. Finally the technology is illustrated by design examples and the outlook for future hydropneumatic suspensions is discussed. (orig.)

  15. Suspension Trauma / Orthostatic Intolerance

    Science.gov (United States)

    ... Suspension Trauma/Orthostatic Intolerance Safety and Health Information Bulletin SHIB 03-24-2004, updated 2011 This Safety ... the harness, the environmental conditions, and the worker's psychological state all may increase the onset and severity ...

  16. The Mystical Suspension

    Directory of Open Access Journals (Sweden)

    Héctor Santiesteban Oliva

    2016-11-01

    Full Text Available Mistical suspension, silence, time, absolute, ontology, ineffability, aletheiaIn the mystical ecstasy there is a sensorial and intellectual suspension when contemplating the absolute, the ontological Being. Silence is not only significant: it is revealing. The greatest expression of experience inner silence . The word is insufficient when the ontological reality is revealed. Revelation or truth , the Greek concept of aletheia, takes on greater significance in that transcendental experience. It is also suspended phenomenological time and remains eternity open.

  17. Minimally invasive brow suspension for facial paralysis.

    Science.gov (United States)

    Costantino, Peter D; Hiltzik, David H; Moche, Jason; Preminger, Aviva

    2003-01-01

    To report a new technique for unilateral brow suspension for facial paralysis that is minimally invasive, limits supraciliary scar formation, does not require specialized endoscopic equipment or expertise, and has proved to be equal to direct brow suspension in durability and symmetry. Retrospective survey of a case series of 23 patients between January 1997 and December 2000. Metropolitan tertiary care center. Patients with head and neck tumors and brow ptosis caused by facial nerve paralysis. The results of the procedure were determined using the following 3-tier rating system: outstanding (excellent elevation and symmetry); acceptable (good elevation and fair symmetry); and unacceptable (loss of elevation). The results were considered outstanding in 12 patients, acceptable in 9 patients, and unacceptable in only 1 patient. One patient developed a hematoma, and 1 patient required a secondary adjustment. The technique has proved to be superior to standard brow suspension procedures with regard to scar formation and equal with respect to facial symmetry and suspension. These results have caused us to abandon direct brow suspension and to use this minimally invasive method in all cases of brow ptosis due to facial paralysis.

  18. Técnicas para avaliação da consolidação de suspensões cerâmicas com o uso de diferentes ligantes Techniques for setting evaluation of ceramic suspensions with different binders

    Directory of Open Access Journals (Sweden)

    I. R. Oliveira

    2007-06-01

    Full Text Available O desenvolvimento de concretos refratários avançados exige uma otimização simultânea das propriedades reológicas (fluidez e trabalhabilidade e do tempo de desmoldagem desses materiais. Geralmente, tais propriedades, bem como as variáveis que as influenciam, são avaliadas diretamente no concreto refratário por meio de medidas de fluidez e da resistência mecânica. Tal procedimento demanda tempo e limita a investigação sobre todas as possíveis combinações de variáveis que podem influenciar o mecanismo de consolidação a partir de diferentes agentes ligantes. Neste contexto, esse trabalho tem como objetivo apresentar técnicas alternativas que podem facilitar a avaliação da consolidação de suspensões cerâmicas com o uso de diferentes ligantes, correlacionando propriedades macroscópicas como trabalhabilidade e o tempo de desmoldagem de concretos refratários. Tais técnicas consistem em medidas de condutividade elétrica, da temperatura, dos módulos de armazenamento (G' e de perda (G" dos materiais (ensaios reológicos oscilatórios, e da resistência do material a uma deformação axial imposta (ensaios reológicos de força normal.The development of advanced refractory castables demands a simultaneous optimization of rheological properties (fluidity and workability and the time for demolding. Generally, such properties and the variables that influence them, (temperature and additives are directly evaluated in the refractory castable. Nevertheless, such procedure demands time and limits the investigation related to the variables that can influence the suspensions consolidation mechanism. In this context, the objective of this work is to present alternative techniques that could better evaluate the setting of ceramic suspensions containing different binders. The results obtained can be correlated with castable macroscopic properties such as workability and demolding time. These techniques comprise the measurements of

  19. Spray-dried HPMC microparticles of Indomethacin: Impact of drug-polymer ratio and viscosity of the polymeric solution on dissolution

    International Nuclear Information System (INIS)

    Alanazi, Fars K.; El-Badry, M.; Alsarra, Ibrahim A.

    2006-01-01

    Polymeric microparticles prepared by spray-drying techniques were investigated to enhance the dissolution rate of indomethacin (IM) in comparison with conventional microparticles prepared by co-precipitation solid dispersion method. Drug-polymer ratios and viscosity of polymeric solutions as potential factors were used in order to enhance the dissolution rate of IM. Spray-drying technique was used for preparing of microparticles using aqueous suspension of IM in hydroxypropyl methylcellulose (HPMC) polymer solution. The effect of drug-polymer ratios on dissolution rates of IM was studied in simulating intestinal medium. IM was analyzed spectrophotometrically at λ =320nm. For each drug-polymer ratios, low and high viscosity polymeric solutions were prepared and their impacts on the dissolution of IM were observed. Microparticles were morphologically characterized by optical microscopy. The interaction between IM and HPMC was studied by differential scanning caloremetry (DSC) and x-ray diffractometry (XRD). Spherical fluffy microparticles of IM were obtained using HPMC. It was observed that the prepared spray-dried microparticles significantly increase the dissolution rate of IM. The increase in dissolution rates was achieved with drug: polymer ratios 1: 1 as well as 1:2 and interestingly, the decrease in drug content in ratio exceeding 1:2 resulted in reduction in dissolution rates. Also, with all drug-polymer ratios, the low viscosity polymeric solutions gave the higher dissolution rates. In conclusion, HPMC microparticles loaded with IM were prepared by spray drying-technique and the potential of this technique to enhance the dissolution was studied. The findings indicate that the dissolution profile of IM microparticles prepared by spray -drying technique relied on drug-polymer ratios and viscosity of polymeric solutions. (author)

  20. Preparation of super absorbent by irradiation polymerization

    International Nuclear Information System (INIS)

    Hua Fengjun; Tan Chunhong; Qian Mengping

    1995-01-01

    A kind of absorbent is prepared by gamma-rays irradiated by reversed-phase suspension polymerization. Drying particles have 1400 (g/g) absorbency in de-ionic water. Effects of reactive conditions, e.g.: dose-rate, dose, monomer concentration, degree of monomer neutralization and crosslinking agents on absorbency in de-ionic water are discussed. The cause of absorbing de-ionic water by polymer is related to its network structure and ionic equilibrium in particle. Accordingly, a suit reactive condition is chosen for preparation of hydro gel spheres

  1. Advanced treatment technique for swine wastewater using two agents: Thermally polymerized amorphous silica and hydrated lime for color and phosphorus removal and sulfur for nitrogen removal.

    Science.gov (United States)

    Hasegawa, Teruaki; Kurose, Yohei; Tanaka, Yasuo

    2017-10-01

    The efficacy of advanced treatment of swine wastewater using thermally polymerized, modified amorphous silica and hydrated lime (M-CSH-lime) for color and phosphorus removal and sulfur for nitrogen removal was examined with a demonstration-scale treatment plant. The color removal rate was approximately 78% at M-CSH-lime addition rates of > 0.055 wt/v%. The PO43--P removal rate exceeded 99.9% with > 0.023 wt/v%. pH of the effluent from the M-CSH-lime reactor increased with the addition rate till a maximum value of 12.7, which was effective in disinfection. The recovered M-CSH-lime would be suitable as a phosphorus fertilizer because the total P 2 O 5 content was approximately 10%. The nitrogen oxide (NOx-N) removal rate by sulfur denitrification increased to approximately 80% when the NOx-N loading rate was around 0.1 kg-N/ton-S/day. It was suggested that the combination of the two processes would be effective in the advanced treatment of swine wastewater. © 2017 Japanese Society of Animal Science.

  2. A novel technique using potassium permanganate and reflectance confocal microscopy to image biofilm extracellular polymeric matrix reveals non-eDNA networks in Pseudomonas aeruginosa biofilms.

    Science.gov (United States)

    Swearingen, Matthew C; Mehta, Ajeet; Mehta, Amar; Nistico, Laura; Hill, Preston J; Falzarano, Anthony R; Wozniak, Daniel J; Hall-Stoodley, Luanne; Stoodley, Paul

    2016-02-01

    Biofilms are etiologically important in the development of chronic medical and dental infections. The biofilm extracellular polymeric substance (EPS) determines biofilm structure and allows bacteria in biofilms to adapt to changes in mechanical loads such as fluid shear. However, EPS components are difficult to visualize microscopically because of their low density and molecular complexity. Here, we tested potassium permanganate, KMnO4, for use as a non-specific EPS contrast-enhancing stain using confocal laser scanning microscopy in reflectance mode. We demonstrate that KMnO4 reacted with EPS components of various strains of Pseudomonas, Staphylococcus and Streptococcus, yielding brown MnO2 precipitate deposition on the EPS, which was quantifiable using data from the laser reflection detector. Furthermore, the MnO2 signal could be quantified in combination with fluorescent nucleic acid staining. COMSTAT image analysis indicated that KMnO4 staining increased the estimated biovolume over that determined by nucleic acid staining alone for all strains tested, and revealed non-eDNA EPS networks in Pseudomonas aeruginosa biofilm. In vitro and in vivo testing indicated that KMnO4 reacted with poly-N-acetylglucosamine and Pseudomonas Pel polysaccharide, but did not react strongly with DNA or alginate. KMnO4 staining may have application as a research tool and for diagnostic potential for biofilms in clinical samples. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  3. Cotton fibers encapsulated with homo- and block copolymers: synthesis by the atom transfer radical polymerization grafting-from technique and solid-state NMR dynamic investigations.

    Science.gov (United States)

    Castelvetro, Valter; Geppi, Marco; Giaiacopi, Simone; Mollica, Giulia

    2007-02-01

    Cotton fibers were modified by surface-initiated atom transfer radical polymerization of ethyl acrylate (EA) followed by copolymerization with styrene. Either ethyl 2-bromopropionate as a sacrificial free initiator or Cu(II) as a deactivator was used to optimize the EA grafting yield and to preserve the livingness of the chain ends for the subsequent growth of a poly(styrene) (PSty) block from the poly(ethyl acrylate) (PEA) grafts. The polymer-encapsulated cotton fibers were analyzed by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry (DSC), thermogravimetric analysis, and solid-state NMR (high-resolution 13C cross-polarization magic angle spinning, 1H spin-lattice relaxation times, and 1H free induction decay analysis NMR). The latter allowed the detection of the dynamic modifications associated with the presence of homo- and block copolymer grafts. In particular, the results of the DSC and NMR investigations suggest a heterogeneous morphology of the g-PEA-b-PSty grafted skin, which could be described as an inner layer of g-PEA sandwiched between the semicrystalline cellulose of the core fiber and the high glass transition temperature PSty of the covalently linked outer layer. Such morphology results in a reduced molecular mobility of the PEA chains.

  4. Hybrid superconducting magnetic suspensions

    International Nuclear Information System (INIS)

    Tixador, P.; Hiebel, P.; Brunet, Y.; Chaud, X.; Gautier-Picard, P.

    1996-01-01

    Superconductors, especially high T c ones, are the most attractive materials to design stable and fully passive magnetic suspensions which have to control five degrees of freedom. The hybrid superconducting magnetic suspensions present high performances and a simple cooling mode. They consist of a permanent magnet bearing, stabilized by a suitable magnet-superconductor structure. Several designs are given and compared in terms of forces and stiffnesses. The design of the magnet bearing plays an important part. The superconducting magnetic bearing participates less in levitation but must provide a high stabilizing stiffness. This is achieved by the magnet configuration, a good material in term of critical current density and field cooling. A hybrid superconducting suspension for a flywheel is presented. This system consists of a magnet thrust bearing stabilized by superconductors interacting with an alternating polarity magnet structure. First tests and results are reported. Superconducting materials are magnetically melt-textured YBaCuO

  5. Magnetic Suspension Technology Workshop

    International Nuclear Information System (INIS)

    Keckler, C.R.; Groom, N.J.; Britcher, C.P.

    1993-01-01

    In order to identify the state of magnetic suspension technology in such areas as rotating systems, pointing of experiments or subsystems, payload isolation, and superconducting materials, a workshop on Magnetic Suspension Technology was held at the Langley Research Center in Hampton, Virginia, on 2-4 Feb. 1988. The workshop included five technical sessions in which a total of 24 papers were presented. The technical sessions covered the areas of pointing, isolation, and measurement, rotating systems, modeling and control, and superconductors. A list of attendees is provided. Separate abstracts have been prepared for articles from this report

  6. Compressible Fluid Suspension Performance Testing

    National Research Council Canada - National Science Library

    Hoogterp, Francis

    2003-01-01

    ... compressible fluid suspension system that was designed and installed on the vehicle by DTI. The purpose of the tests was to evaluate the possible performance benefits of the compressible fluid suspension system...

  7. Multiobjective suspension control problem

    NARCIS (Netherlands)

    Jager, de A.G.

    1995-01-01

    The paper describes a (controller) design problem in the field of suspension systems for transport vehicles. A ten degrees-of-freedom model for a tractor-semitrailer vehicle is presented, using parameters derived from a real vehicle, which should be used for design and verification purposes. Road

  8. Preparation of conjugated polymer suspensions by using ultrasonic atomizer

    Energy Technology Data Exchange (ETDEWEB)

    Tada, Kazuya, E-mail: tada@eng.u-hyogo.ac.jp; Onoda, Mitsuyoshi

    2010-11-30

    The electrophoretic deposition is a method useful to prepare conjugated polymer films for electronic devices. This method provides high material recovery rate on the substrate from the suspension, in contrast to the conventional spin-coating in which most of the material placed on the substrate is blown away. Although manual reprecipitation technique successfully yields suspensions of various conjugated polymers including polyfluorene derivatives, it is favorable to control the preparation process of suspensions. In this context, this paper reports preliminary results on the preparation of suspension of conjugated polymer by using an ultrasonic atomizer. While the resultant films do not show particular difference due to the preparation methods of the suspension, the electric current profiles during the electrophoretic deposition suggests that the ultrasonic atomization of polymer solution prior to be mixed with poor solvent results in smaller and less uniform colloidal particles than the conventional manual pouring method.

  9. Reproducibility of measurement of the environmental carbon-14 samples prepared by the gel suspension method

    International Nuclear Information System (INIS)

    Ohura, Hirotaka; Wakabayashi, Genichiro; Nakamura, Kouji; Okai, Tomio; Matoba, Masaru; Kakiuchi, Hideki; Momoshima, Noriyuki; Kawamura, Hidehisa.

    1997-01-01

    Simple liquid scintillation counting technique for the assay of 14 C in the environment was developed. This technique was done by using gel suspension method, in which sample preparation is very simple and requires no special equipments. The reproducibility of this technique was considered and it was shown that the gel suspension method had enough reproducibility to monitor the environmental 14 C. (author)

  10. Designing of fluorescent and magnetic imprinted polymer for rapid, selective and sensitive detection of imidacloprid via activators regenerated by the electron transfer-atom transfer radical polymerization (ARGET-ATRP) technique

    Science.gov (United States)

    Kumar, Sunil; Karfa, Paramita; Madhuri, Rashmi; Sharma, Prashant K.

    2018-05-01

    In this work, we report on a dual-behavior electrochemical/optical sensor for sensitive determination of Imidacloprid by fluorescent dye (fluorescein, FL) and imprinted polymer modified europium doped superparamagnetic iron oxide nanoparticles (FL@SPIONs@MIP). The imidacloprid (IMD)-imprinted polymer was directly synthesized on the Eu-SPIONs surface via Activators regenerated by the electron transfer-atom transfer radical polymerization (ARGET-ATRP) technique. Preparation, characterization and application of the prepared FL@SPIONs@MIP were systematically investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), fluorescence spectroscopy and electrochemical techniques. The electrochemical experiments exhibited a remarkable selectivity of the prepared sensor towards IMD. Determination of IMD by the square wave stripping voltammetry method represented a wide linear range of 0.059-0.791 μg L-1 with a detection limit of 0.0125 μg L-1. In addition, the fluorescence method shows a linear range of 0.039-0.942 μg L-1 and LOD of 0.0108 μg L-1. The fluorescence property of prepared FL@SPIONs@MIP was used for rapid, on-spot but selective detection of IMD in real samples. The proposed electrode displayed excellent repeatability and long-term stability and was successfully applied for quantitative and trace level determination of IMD in several real samples.

  11. Applied bioactive polymeric materials

    CERN Document Server

    Carraher, Charles; Foster, Van

    1988-01-01

    The biological and biomedical applications of polymeric materials have increased greatly in the past few years. This book will detail some, but not all, of these recent developments. There would not be enough space in this book to cover, even lightly, all of the major advances that have occurred. Some earlier books and summaries are available by two of this book's Editors (Gebelein & Carraher) and these should be consul ted for additional information. The books are: "Bioactive Polymeric Systems" (Plenum, 1985); "Polymeric Materials In Medication" (Plenum, 1985); "Biological Acti vi ties of Polymers" (American Chemical Society, 1982). Of these three, "Bioacti ve Polymeric Systems" should be the most useful to a person who is new to this field because it only contains review articles written at an introductory level. The present book primarily consists of recent research results and applications, with only a few review or summary articles. Bioactive polymeric materials have existed from the creation of life...

  12. The tempered polymerization of human neuroserpin.

    Directory of Open Access Journals (Sweden)

    Rosina Noto

    Full Text Available Neuroserpin, a member of the serpin protein superfamily, is an inhibitor of proteolytic activity that is involved in pathologies such as ischemia, Alzheimer's disease, and Familial Encephalopathy with Neuroserpin Inclusion Bodies (FENIB. The latter belongs to a class of conformational diseases, known as serpinopathies, which are related to the aberrant polymerization of serpin mutants. Neuroserpin is known to polymerize, even in its wild type form, under thermal stress. Here, we study the mechanism of neuroserpin polymerization over a wide range of temperatures by different techniques. Our experiments show how the onset of polymerization is dependent on the formation of an intermediate monomeric conformer, which then associates with a native monomer to yield a dimeric species. After the formation of small polymers, the aggregation proceeds via monomer addition as well as polymer-polymer association. No further secondary mechanism takes place up to very high temperatures, thus resulting in the formation of neuroserpin linear polymeric chains. Most interesting, the overall aggregation is tuned by the co-occurrence of monomer inactivation (i.e. the formation of latent neuroserpin and by a mechanism of fragmentation. The polymerization kinetics exhibit a unique modulation of the average mass and size of polymers, which might suggest synchronization among the different processes involved. Thus, fragmentation would control and temper the aggregation process, instead of enhancing it, as typically observed (e.g. for amyloid fibrillation.

  13. Constraint Embedding for Vehicle Suspension Dynamics

    Directory of Open Access Journals (Sweden)

    Jain Abhinandan

    2016-06-01

    Full Text Available The goal of this research is to achieve close to real-time dynamics performance for allowing auto-pilot in-the-loop testing of unmanned ground vehicles (UGV for urban as well as off-road scenarios. The overall vehicle dynamics performance is governed by the multibody dynamics model for the vehicle, the wheel/terrain interaction dynamics and the onboard control system. The topic of this paper is the development of computationally efficient and accurate dynamics model for ground vehicles with complex suspension dynamics. A challenge is that typical vehicle suspensions involve closed-chain loops which require expensive DAE integration techniques. In this paper, we illustrate the use the alternative constraint embedding technique to reduce the cost and improve the accuracy of the dynamics model for the vehicle.

  14. Modelling nonlinear viscoelastic behaviours of loudspeaker suspensions-like structures

    Science.gov (United States)

    Maillou, Balbine; Lotton, Pierrick; Novak, Antonin; Simon, Laurent

    2018-03-01

    Mechanical properties of an electrodynamic loudspeaker are mainly determined by its suspensions (surround and spider) that behave nonlinearly and typically exhibit frequency dependent viscoelastic properties such as creep effect. The paper aims at characterizing the mechanical behaviour of electrodynamic loudspeaker suspensions at low frequencies using nonlinear identification techniques developed in recent years. A Generalized Hammerstein based model can take into account both frequency dependency and nonlinear properties. As shown in the paper, the model generalizes existing nonlinear or viscoelastic models commonly used for loudspeaker modelling. It is further experimentally shown that a possible input-dependent law may play a key role in suspension characterization.

  15. Biocompatible Polymeric Materials Intended for Drug Delivery and Therapeutic Applications

    DEFF Research Database (Denmark)

    Hvilsted, Søren; Javakhishvili, Irakli; Bednarek, Melania

    2007-01-01

    of polymer blocks by “click chemistry”. An all polymerization strategy would imply preparing polymers by living/controlled techniques in such a manner that one block after polymerization can be converted to a macroinitiator enabling the second block to polymerize. The coupling strategy invariably inserts...... a linking unit, 1,4-triazol, resulting from the catalyzed, irreversible 1,3-dipolar cycloaddition reaction between an alkyne and an azide. Thus, this strategy necessitates the proper end functionalization of the polymeric building blocks. Fortunately the 1,4-triazol unit is FDA approved already existing...

  16. Yield stress of alumina-zirconia suspensions

    International Nuclear Information System (INIS)

    Ramakrishnan, V.; Pradip; Malghan, S.G.

    1996-01-01

    The yield stress of concentrated suspensions of alumina, zirconia, and mixed alumina-zirconia powders was measured by the vane technique as a function of solids loading, relative amounts of alumina and zirconia, and pH. At the isoelectric point (IEP), the yield stress varied as the fourth power of the solids loading. The relative ratio of alumina and zirconia particles was important in determining the yield stress of the suspension at the IEP. The yield stress of single and mixed suspensions showed a marked variation with pH. The maximum value occurred at or near the IEP of the suspension. The effect of electrical double-layer forces on the yield stress can be described on the basis of the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. A normalized yield stress--that is, the ratio of the yield stress at a given pH to the yield stress at the IEP predicted by this model--showed good correlation with experimental data

  17. electrocatalytic reduction of oxygen at vapor phase polymerized poly ...

    African Journals Online (AJOL)

    Preferred Customer

    ABSTRACT. We successfully polymerized poly(3,4-ethylenedioxidethiophene) by vapor phase polymerization technique on rotating glassy carbon disk electrode. The catalytic activity of this electrode towards oxygen reduction reaction was investigated and showed remarkable activity. Rotating disk voltammetry was used to ...

  18. Electrocatalytic reduction of oxygen at vapor phase polymerized ...

    African Journals Online (AJOL)

    We successfully polymerized poly(3,4-ethylenedioxidethiophene) by vapor phase polymerization technique on rotating glassy carbon disk electrode. The catalytic activity of this electrode towards oxygen reduction reaction was investigated and showed remarkable activity. Rotating disk voltammetry was used to study the ...

  19. Optimal Vibration Control for Tracked Vehicle Suspension Systems

    Directory of Open Access Journals (Sweden)

    Yan-Jun Liang

    2013-01-01

    Full Text Available Technique of optimal vibration control with exponential decay rate and simulation for vehicle active suspension systems is developed. Mechanical model and dynamic system for a class of tracked vehicle suspension vibration control is established and the corresponding system of state space form is described. In order to prolong the working life of suspension system and improve ride comfort, based on the active suspension vibration control devices and using optimal control approach, an optimal vibration controller with exponential decay rate is designed. Numerical simulations are carried out, and the control effects of the ordinary optimal controller and the proposed controller are compared. Numerical simulation results illustrate the effectiveness of the proposed technique.

  20. Magnetic suspension - Today's marvel, tomorrow's tool

    Science.gov (United States)

    Lawing, Pierce L.

    1989-01-01

    NASA's Langley facility has through constant advocacy of magnetic suspension systems (MSSs) for wind-tunnel model positioning obtained a technology-development status for the requisite large magnets, computers, automatic control techniques, and apparatus configurations, to contemplate the construction of MSSs for large wind tunnels. Attention is presently given to the prospects for MSSs in wind tunnels employing superfluid helium atmospheres to obtain very high Reynolds numbers, where the MSS can yield substantial enhancements of wind tunnel productivity.

  1. A universal suspension test rig for electrohydraulic active and passive automotive suspension system

    Directory of Open Access Journals (Sweden)

    Mahmoud Omar

    2017-12-01

    Full Text Available A fully active electro-hydraulic and passive automotive quarter car suspensions with their experimental test-rigs are designed and implemented. Investigation of the active performance compared against the passive is performed experimentally and numerically utilizing SIMULINK's Simscape library. Both systems are modeled as single-degree-of-freedom in order to simplify the validation process. Economic considerations were considered during the rig's implementation. The rig consists of two identical platforms fixed side by side allowing testing two independent suspensions simultaneously. Position sensors for sprung and unsprung masses on both platforms are installed. The road input is introduced by a cam and a roller follower mechanism driven by 1.12 kW single phase induction motor with speed reduction assembly. The active hydraulic cylinder was the most viable choice due to its high power-to-weight ratio. The active control is of the proportional-integral-differential (PID type. Though this technique is quite simple and not new, yet the emphasis of this paper is the engineering, design and implementation of the experimental setup and controller. A successful validation process is performed. Ride comfort significantly improved with active suspension, as shown by the results; 24.8% sprung mass vibration attenuation is achieved. The details of the developed system with the analytical and experimental results are presented. Keywords: Active suspension, Passive suspension, Servo, Hydraulic, Control, PID

  2. Efeito das técnicas de inserção e ativação da resina composta sobre a microinfiltração e microdureza Effect of techniques of composite resin insertion and polymerization on microleakage and microhardness

    Directory of Open Access Journals (Sweden)

    Cristiane Mariote Amaral

    2002-09-01

    Full Text Available O objetivo deste trabalho foi avaliar a influência da técnica de ativação e de inserção da resina composta sobre a microinfiltração marginal e microdureza em restaurações classe II. Foram preparadas 180 cavidades que foram divididas em 6 grupos: G1 - incremento único + ativação convencional; G2 - incrementos vestíbulo-linguais + ativação convencional; G3 - incremento único + ativação "soft-start"; G4 - incrementos vestíbulo-linguais + ativação "soft-start"; G5 - incremento único + ativação progressiva; G6 - incrementos vestíbulo-linguais + ativação progressiva. Todas as cavidades foram restauradas com o sistema Z100/Single Bond (3M. Após 1.000 ciclos térmicos (5 e 55ºC, os espécimes foram imersos em solução aquosa de azul de metileno a 2%, por 4 horas e a microinfiltração foi avaliada. Metade dos espécimes foram incluídos em resina de poliestireno e a microdureza Knoop foi avaliada. Após o teste Kruskal-Wallis, não foi observada diferença significativa (p > 0,05 entre todas as técnicas de ativação e de inserção quanto à microinfiltração. Quanto à microdureza, após os testes análise de variância (2 fatores e Tukey, não houve diferença significativa entre as técnicas restauradoras empregadas (p > 0,05, porém a ativação progressiva (G5 e G6 apresentou menor dureza Knoop (p The aim of this study was to evaluate the influence of techniques of composite resin polymerization and insertion on microleakage and microhardness. One hundred and eighty class II cavities were prepared in bovine teeth and assigned to six groups: G1 - bulk filling + conventional polymerization; G2 - bucco-lingual increments + conventional polymerization; G3 - bulk filling + soft-start polymerization; G4 - bucco-lingual increments + soft-start polymerization; G5 - bulk filling + progressive polymerization; G6 - bucco-lingual increments + progressive polymerization. All cavities were restored with the Z100/Single Bond

  3. Polymeric bicontinuous microemulsions

    DEFF Research Database (Denmark)

    Bates, F.S.; Maurer, W.W.; Lipic, P.M.

    1997-01-01

    High molecular weight block copolymers can be viewed as macromolecular surfactants when blended with thermodynamically incompatible homopolymers. This Letter describes the formation of polymeric bicontinuous microemulsions in nurtures containing a model diblock copolymer and two homopolymers. Alt...

  4. Polymerization Using Phosphazene Bases

    KAUST Repository

    Zhao, Junpeng; Hadjichristidis, Nikolaos; Schlaad, Helmut

    2015-01-01

    . In this chapter, the general features of phosphazenepromoted/catalyzed polymerizations and the applications in macromolecular engineering (synthesis of functionalized polymers, block copolymers, and macromolecular architectures) are discussed with challenges

  5. Rheological Properties of Aqueous Nanometric Alumina Suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chuanping [Iowa State Univ., Ames, IA (United States)

    2004-01-01

    Colloidal processing is an effective and reliable approach in the fabrication of the advanced ceramic products. Successful colloidal processing of fine ceramic powders requires accurate control of the rheological properties. The accurate control relies on the understanding the influences of various colloidal parameters on the rheological properties. Almost all research done on the rheology paid less attention to the interactions of particle and solvent. However, the interactions of the particles are usually built up through the media in which the particles are suspended. Therefore, interactions of the particle with the media, the adsorbed layers on the particle surface, and chemical and physical properties of media themselves must influence the rheology of the suspension, especially for the dense suspensions containing nanosized particles. Relatively little research work has been reported in this area. This thesis addresses the rheological properties of nanometric alumina aqueous suspensions, and paying more attention to the interactions between particle and solvent, which in turn influence the particle-particle interactions. Dense nanometric alumina aqueous suspensions with low viscosity were achieved by environmentally-benign fructose additives. The rheology of nanometric alumina aqueous suspensions and its variation with the particle volume fraction and concentration of fructose were explored by rheometry. The adsorptions of solute (fructose) and solvent (water) on the nanometric alumina particle surfaces were measured and analyzed by TG/DSC, TOC, and NMR techniques. The mobility of water molecules in the suspensions and its variation with particle volume fractions and fructose additive were determined by the 17O NMR relaxation method. The interactions between the nanometric alumina particles in water and fructose solutions were investigated by AFM. The results indicated that a large number of water layers were physically bound on the particles

  6. Uso da fáscia temporal na suspensão frontal: descrição da técnica cirúrgica - Relato de caso Use of temporal fascia in frontalis suspension: description of the surgical technique - Case report

    Directory of Open Access Journals (Sweden)

    Tânia Pereira Nunes

    2004-04-01

    Full Text Available OBJETIVOS: Familiarizar o oftalmologista com a anatomia da região temporal, descrever a técnica cirúrgica da retirada da fáscia temporal e da suspensão frontal e analisar as vantagens e desvantagens da fáscia temporal na suspensão frontal. MÉTODOS: Revisão do prontuário de uma paciente com blefaroptose grave que foi submetida à suspensão frontal com fáscia temporal. Revisão da anatomia da fossa temporal e das técnicas cirúrgicas. RESULTADOS: Bom resultado estético e funcional foi conseguido no caso descrito. CONCLUSÃO: A fáscia temporal é boa opção na suspensão frontal com algumas vantagens: é um tecido autógeno, de fácil obtenção e mínima morbidade no pós-operatório.PURPOSE: To familiarize the ophthalmologist with the anatomy of the temporal region, to describe the surgical technique of temporal fascia harvest and frontalis suspension and to demonstrate advantages and disadvantages of temporal fascia in frontalis suspension. METHODS: Review of the clinical and surgical data of one case with severe blepharoptosis who underwent frontalis suspension using temporal fascia. Review of the anatomy of the temporal fossa and the surgical techniques. RESULTS: Good esthetic and functional results were obtained in this case. CONCLUSION: Temporal fascia is a good choice for frontalis suspension with some advantages: it is autogenous, it is easily harvested and it yields minimal post-operative morbidity.

  7. Radical-Mediated Enzymatic Polymerizations

    Science.gov (United States)

    Zavada, Scott R.; Battsengel, Tsatsral; Scott, Timothy F.

    2016-01-01

    Polymerization reactions are commonly effected by exposing monomer formulations to some initiation stimulus such as elevated temperature, light, or a chemical reactant. Increasingly, these polymerization reactions are mediated by enzymes―catalytic proteins―owing to their reaction efficiency under mild conditions as well as their environmental friendliness. The utilization of enzymes, particularly oxidases and peroxidases, for generating radicals via reduction-oxidation mechanisms is especially common for initiating radical-mediated polymerization reactions, including vinyl chain-growth polymerization, atom transfer radical polymerization, thiol–ene step-growth polymerization, and polymerization via oxidative coupling. While enzyme-mediated polymerization is useful for the production of materials intended for subsequent use, it is especially well-suited for in situ polymerizations, where the polymer is formed in the place where it will be utilized. Such polymerizations are especially useful for biomedical adhesives and for sensing applications. PMID:26848652

  8. Chelating polymeric membranes

    KAUST Repository

    Peinemann, Klaus-Viktor

    2015-01-22

    The present application offers a solution to the current problems associated with recovery and recycling of precious metals from scrap material, discard articles, and other items comprising one or more precious metals. The solution is premised on a microporous chelating polymeric membrane. Embodiments include, but are not limited to, microporous chelating polymeric membranes, device comprising the membranes, and methods of using and making the same.

  9. Use of magnetic beads for Gram staining of bacteria in aqueous suspension.

    Science.gov (United States)

    Yazdankhah, S P; Sørum, H; Larsen, H J; Gogstad, G

    2001-12-01

    A Gram staining technique was developed using monodisperse magnetic beads in concentrating bacteria in suspension for downstream application. The technique does not require heat fixation of organisms, electrical power, or a microscope. Gram-negative and Gram-positive bacteria were identified macroscopically based on the colour of the suspension. The bacteria concentrated on magnetic beads may also be identified microscopically.

  10. Characteristic emission in glutaraldehyde polymerized hemoglobin

    International Nuclear Information System (INIS)

    Ma Li; Wang Xiaojun

    2011-01-01

    Hemoglobin with different modifications has been investigated using spectroscopic techniques. A new emission at around 371 nm has been observed under excitation of 305 nm from glutaraldehyde polymerized human hemoglobin. Intensity and peak position of the emission are dependent on both oxidation state and ligand environment and the emission has been identified from the hemoglobin oligomer.

  11. Experimental study of living free radical polymerization using trifunctional initiator and polymerization mediated by nitroxide

    International Nuclear Information System (INIS)

    Galhardo, Eduardo; Lona, Liliane M.F.

    2009-01-01

    Controlled free radical polymerization or living free radical polymerization has received increasing attention as a technique for the production of polymers with microstructure highly controlled. In particular, narrow molecular weight distributions are obtained with polydispersity very close to one. In this research it was investigate the controlled polymerization mediated by nitroxide, using a cyclic trifunctional peroxide. As long as we know, there are only publications in literature dealing with NMRP using mono- and bi-functional initiators. It was believed that the trifunctional peroxide can increase the rate of polymerization, since more free radicals are generated, if compared with initiators with lower functionality. Furthermore, the fact of the initiator be cyclic means that branches are not generated in the chains, which theoretically prevents an increase in polydispersity of the polymer. The effect of the dissociation constant of the trifunctional initiator in the velocity of the reaction was analyzed. (author)

  12. Functional polypeptides obtained by living ring opening polymerizations of N-carboxyanhydrides

    NARCIS (Netherlands)

    Habraken, G.J.M.

    2011-01-01

    N-Carboxyanhydride ring opening polymerization (NCA ROP) is a method to prepare polypeptides with a high degree of polymerization in large quantities. The living polymerization technique of NCA ROP gave the opportunity to synthesize many polymer architectures with well-defined blocks and copolymers

  13. Characterization of Complex Colloidal Suspensions

    Science.gov (United States)

    Seaman, J. C.; Guerin, M.; Jackson, B. P.; Ranville, J. M.

    2003-04-01

    Surface chemical reactions play a major role in controlling contaminant fate and transport in the subsurface environment. Recent field and laboratory evidence suggests that mobile soil and groundwater colloids may facilitate the migration of sparingly soluble groundwater contaminants. Colloidal suspensions collected in the field or generated in laboratory column experiments tend to be fairly dilute in nature and comprised of relatively small particulates (reserved for studying ideal systems to the characterization of mobile colloids. However, many of these analytical techniques, including total/selective dissolution methods, dynamic light scattering, micro-electrophoresis, streaming potential, and even scanning electron microscopy (SEM), can be biased in of larger size fractions, and therefore, extremely sensitive to sampling, storage, and fractionation artifacts. In addition, surface modifiers such as sorbed oxides or organics can alter particulate appearance, composition, and behavior when compared to synthetic analogues or mineral standards. The current presentation will discuss the limitations and inherent biases associated with a number of analytical characterization techniques that are commonly applied to the study of mobile soil and groundwater colloids, including field flow fractionation (FFF) and acoustic based methods that have only recently become available.

  14. Heterofunctional Glycopolypeptides by Combination of Thiol-Ene Chemistry and NCA Polymerization.

    Science.gov (United States)

    Krannig, Kai-Steffen; Schlaad, Helmut

    2016-01-01

    Glycopolypeptides are prepared either by the polymerization of glycosylated amino acid N-carboxyanhydrides (NCAs) or by the post-polymerization functionalization of polypeptides with suitable functional groups. Here we present a method for the in-situ functionalization and (co-) polymerization of allylglycine N-carboxyanhydride in a facile one-pot procedure, combining radical thiol-ene photochemistry and nucleophilic ring-opening polymerization techniques, to yield well-defined heterofunctional glycopolypeptides.

  15. Tribology of polymeric nanocomposites friction and wear of bulk materials and coatings

    CERN Document Server

    Friedrich, Klaus

    2013-01-01

    Tribology of Polymeric Nanocomposites provides a comprehensive description of polymeric nanocomposites, both as bulk materials and as thin surface coatings, and provides rare, focused coverage of their tribological behavior and potential use in tribological applications. Providing engineers and designers with the preparation techniques, friction and wear mechanisms, property information and evaluation methodology needed to select the right polymeric nanocomposites for the job, this unique book also includes valuable real-world examples of polymeric nanocomposites in a

  16. Suspensions of colloidal particles and aggregates

    CERN Document Server

    Babick, Frank

    2016-01-01

    This book addresses the properties of particles in colloidal suspensions. It has a focus on particle aggregates and the dependency of their physical behaviour on morphological parameters. For this purpose, relevant theories and methodological tools are reviewed and applied to selected examples. The book is divided into four main chapters. The first of them introduces important measurement techniques for the determination of particle size and interfacial properties in colloidal suspensions. A further chapter is devoted to the physico-chemical properties of colloidal particles—highlighting the interfacial phenomena and the corresponding interactions between particles. The book’s central chapter examines the structure-property relations of colloidal aggregates. This comprises concepts to quantify size and structure of aggregates, models and numerical tools for calculating the (light) scattering and hydrodynamic properties of aggregates, and a discussion on van-der-Waals and double layer interactions between ...

  17. Characterization of alumina suspensions by electroacoustics

    Energy Technology Data Exchange (ETDEWEB)

    Galassi, C.; Roncari, E.; Greenwood, R.; Piancastelli, A. [CNR, Faenza (Italy). Research Inst. for Ceramics Technology

    1997-12-31

    Using the acoustophoresis technique three different dispersants were selected to investigate the effect of the volume fraction of the suspension on the minimum amount of dispersant required to give the maximum zeta potential. No effect was detected over a volume fraction range 0.11 to 0.35. The acoustosizer was used to screen many dispersants for alumina in a relatively short time. From the viewpoint that the most stable suspensions are those with the greatest zeta potentials, then the following dispersants can be recommended: Reotan LA (0.25 mg/m{sup 2}) Dolapix CA (0.20 mg/m{sup 2}) and Dolapix PC33 (0.30 mg/m{sup 2}). Vanisperse and Borresperse are poor. Polyacrylic acid and polymethacrylic acid were better than some commercially available products. (orig.) 2 refs.

  18. Radiation induced emulsion polymerization

    International Nuclear Information System (INIS)

    Stannett, V.T.; Stahel, E.P.

    1990-01-01

    High energy radiation is particularly favored for the initiation of emulsion polymerization. The yield of free radicals, for example, from the radiolysis of the aqueous phase, is high; G(radical) values of 5-7. In addition, the rather special kinetics associated with emulsion polymerization lead, in general, to very large kinetic chain lengths, even with 'non-ideal' monomers such as vinyl acetate. Together, high polymerization rates at low doses become possible. There are some important advantages of radiation polymerization compared with chemical initiators, such as potassium persulfate. Perhaps the most important among them is the temperature independence of the initiation step. This makes low temperature polymerization very accessible. With monomers such as vinyl acetate, where chain termination to monomer is predominant, low temperatures lead to often highly desirable higher molecular weights. With styrene, the classical ideally behaved monomer, there are the advantages such as, for example, the feasibility of using cationic monomers. These and some attendant disadvantages are discussed in detail, including pilot plant studies

  19. Electrospun polymeric nanofibers for transdermal drug delivery

    Directory of Open Access Journals (Sweden)

    Mahya Rahmani

    2017-04-01

    Full Text Available Conventional transdermal drug delivery systems (TDDS have been designed for drug delivery through the skin. These systems use the permeability property of stratum corneum, the outermost surface layer of the skin. Applying polymeric micro and nanofibers in drug delivery has recently attracted great attention and the electrospinning technique is the preferred method for polymeric micro-nanofibers fabrication with a great potential for drug delivery. More studies in the field of nanofibers containing drug are divided two categories: first, preparation and characterization of nanofibers containing drug and second, investigation of their therapeutic applications. Drugs used in electrospun nanofibers can be categorized into three main groups, including antibiotics and antimicrobial agents, anti-inflammatory agents and vitamins with therapeutic applications. In this paper, we review the application of electrospun polymeric scaffolds in TDDS and also introduce several pharmaceutical and therapeutic agents which have been used in polymer nanofibrous patches.

  20. Vinyl acetate polymerization by ionizing radiation

    International Nuclear Information System (INIS)

    Mesquita, Andrea Cercan

    2002-01-01

    The aim of this work is the synthesis and characterization of the poly(vinyl acetate) using the ionizing radiation. Six polymerizations of vinyl acetate were carried out using three techniques of polymerization: in bulk, emulsion and solution. In the technique of solution polymerization were used two solvents, the alcohol ethyl and the methylethylketone, in two proportions 1:0.5 and 1:1 related to the monomer. The solutions were irradiated with gamma rays from a 60 Co source, with dose rate between 5.25 kGy/h and 6.26 kGy/h. The polymers obtained were characterized by Fourier Transform Infrared Spectroscopy (FTIR). The glass transition temperature (Tg) was investigated by Differential Scanning Calorimeter (DSC). The molecular weight was analyzed by the technique of Gel Permeation Chromatography (GPC). Tests of density, hardness and Vicat softening temperature were carried out. The infrared spectroscopy and others results confirmed that the polymers obtained by polymerization of vinyl acetate in bulk, emulsion and solution, using ionizing radiation, really correspond at poly(vinyl acetate). (author)

  1. A novel task specific magnetic polymeric ionic liquid for selective preconcentration of potassium in oil samples using centrifuge-less dispersive liquid-liquid microextraction technique and its determination by flame atomic emission spectroscopy.

    Science.gov (United States)

    Beiraghi, Asadollah; Shokri, Masood

    2018-02-01

    In the present study a new centrifuge-less dispersive liquid-liquid microextraction technique based on application of a new task specific magnetic polymeric ionic liquid (TSMPIL) as a chelating and extraction solvent for selective preconcentration of trace amounts of potassium from oil samples is developed, for the first time. After extraction, the fine droplets of TSMPIL were transferred into an eppendorf tube and diluted to 500µL using distilled water. Then, the enriched analyte was determined by flame atomic emission spectroscopy (FAES). Several important factors affecting both the complexation and extraction efficiency including extraction time, rate of vortex agitator, amount of carbonyl iron powder, pH of sample solution, volume of ionic liquid as well as effects of interfering species were investigated and optimized. Under the optimal conditions, the limits of detection (LOD) and quantification (LOQ) were 0.5 and 1.6µgL -1 respectively with the preconcentration factor of 128. The precision (RSD %) for seven replicate determinations at 10µgL -1 of potassium was better than 3.9%. The relative recoveries for the spiked samples were in the acceptable range of 95-104%. The results demonstrated that no remarkable interferences are created by other various ions in the determination of potassium, so that the tolerance limits (W Ion /W K ) of major cations and anions were in the range of 2500-10,000. The purposed method was successfully applied for the analysis of potassium in some oil samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Study on irradiated polymerization of acrylonitrile by NMR

    International Nuclear Information System (INIS)

    Zhao Xin; Lin Hao

    1999-01-01

    Sup 13 C CP/MAS spectra and nuclear Overhauser effects (NOE) at room temperature have been measured for acrylonitrile (AN) in homophase irradiated polymerization. With the increase of radiation dose the chemical shift of cracking peaks and NOE are variation. This implies that the polymerized mechanism of AN were changed with the variation of irradiated doses and dose rate. There is the stronger affinity electron group (-CN) in acrylonitrile monomer. It may be polymerized by various ways and mechanism and be gained the polymer of difference structures and molecular weight of polyacrylonitrile (PAN). Starmicarbon and Starker obtained higher molecular weight of polyacrylonitrile by peroxysulfate-pyrosulfite in oxidation-reduction system. The superhigh molecular weight of PAN was synthesized chemically according to the method of Wu et. al. by suspension polymerization. In this paper we discussed that the relative concentrations of steric dyads and triads in the chain structure in PAN and the irradiation polymerized mechanism of acrylonitrile monomer in room temperature by different dose and dose rate

  3. Magnetorheological suspension electromagnetic brake

    International Nuclear Information System (INIS)

    Bica, Ioan

    2004-01-01

    The magnetorheological suspension (MRS) brake is of the monoblock type. The main part of the electromagnetic brake is an electromagnet, between whose poles two MRS disks are placed. For distances between disks of 0.65x10 -3 m±10%, revolutions of the electric motor, coupled to the electromagnetic brake, ranging between 200 and 1600 rev/min and braking powers of up to 85 W, there are no differences in revolutions between the disks of the electromagnetic brake. For fixed revolutions of the electric motor, the revolution of the parallel disk can be modified continuously by means of the intensity of the magnetic field. In all cases, the quantity of MRS is of 0.35x10 -3 kg

  4. Plasma polymerization by Softplasma

    DEFF Research Database (Denmark)

    Jiang, J.; Wu, Zhenning; Benter, Maike

    2008-01-01

    , external electrode, and electrodeless microwave or high frequency reactors. [3] Softplasma™ is an internal electrode plasma setup powered by low frequenc~ gower supply. It was developed in late 90s for surface treatment of silicone rubber. [ ]- 5] It is a low pressure, low electron density, 3D homogenous......In the late 19th century, the first depositions - known today as plasma polymers, were reported. In the last century, more and more research has been put into plasma polymers. Many different deposition systems have been developed. [1, 2] Shi F. F. broadly classified them into internal electrode...... plasma. In this study, we are presenting the surface modification"pf polymers by plasma polymerization using Softplasma™. Softplasma™ can be used for two major types of polymerization: polymerization of vinyl monomers, where plasma acts as initiator; chemical vapour deposition, where plasma acts...

  5. Enzymatically-Catalyzed Polymerization (ECP)- Derived Polymer Electrolyte for Rechargeable Li-Ion Batteries

    National Research Council Canada - National Science Library

    Chua, David

    1998-01-01

    Report developed under SBIR contract covers the syntheses and electrochemical characterizations of novel polymer electrolytes derived from compounds synthesized via enzyme-catalyzed polymerization(ECP) techniques...

  6. Inflation of a Polymeric Menbrane

    DEFF Research Database (Denmark)

    Kristensen, Susanne B.; Larsen, Johannes R.; Hassager, Ole

    1998-01-01

    We consider an axisymmetric polymeric membrane inflated by a uniform pressure difference acting across the membrane.......We consider an axisymmetric polymeric membrane inflated by a uniform pressure difference acting across the membrane....

  7. Boundary Effects and Shear Thickening of Colloidal Suspensions: A study based on measurement of Suspension Microstructure

    Science.gov (United States)

    Perera, M. Tharanga D.

    Microstructure is key to understanding rheological behaviors of flowing particulate suspensions. During the past decade, Stokesian Dynamics simulations have been the dominant method of determining suspension microstructure. Structure results obtained numerically reveal that an anisotropic structure is formed under high Peclet (Pe) number conditions. Researchers have used various experimental techniques such as small angle neutron scattering (SANS) and light scattering methods to validate microstructure. This work outlines an experimental technique based on confocal microscopy to study microstructure of a colloidal suspension in an index-matched fluid flowing in a microchannel. High resolution scans determining individual particle locations in suspensions 30-50 vol % yield quantitative results of the local microstructure in the form of the pair distribution function, g(r). From these experimentally determined g(r), the effect of shear rate, quantified by the Peclet number as a ratio of shear and Brownian stress, on the suspension viscosity and normal stress follow that seen in macroscopic rheological measurements and simulations. It is generally believed that shear thickening behavior of colloidal suspensions is driven by the formation of hydroclusters. From measurements of particle locations, hydroclusters are identified. The number of hydroclusters grows exponentially with increasing Pe, and the onset of shear thickening is driven by the increase in formation of clusters having 5-8 particles. At higher Pe, we notice the emergence of 12 or more particle clusters. The internal structure of these hydroclusters has been investigated, and there is some evidence that particles internal to hydroclusters preferentially align along the 45° and 135° axis. Beyond observations of bulk suspension behavior, the influence of boundaries on suspension microstructure is also investigated. Experiments were performed for suspensions flowing over smooth walls, made of glass

  8. Effects of ionizing radiations on reticulated polymers associated to nuclear wastes. The HSF-SIMS technique contribution; Effets des radiations ionisantes sur les polymeres reticules associes aux dechets nucleaires. Apport de la technique HSF-SIMS

    Energy Technology Data Exchange (ETDEWEB)

    Debre, O [Lyon-1 Univ., 69 - Villeurbanne (France). Inst. de Physique Nucleaire

    1997-06-30

    Among the materials used for confinement of nuclear wastes of low and medium level activity the epoxyde resins are known as matrices which preserve well their properties in an ionizing environment. This work is dedicated to the investigation of the modifications occurring in molecular structure of these materials as well as of the ion exchange resins they incorporate, irradiated in different conditions. The first part deals with the analysis of a commercial reticulated epoxyde resin submitted to a 2 MGy integral dose gamma irradiation under two different dose rate (51 and 900 Gy/h), and under two different environments (air and water). The results obtained with the techniques providing structure information (time-of-flight mass spectrometry (HSF-SIMS) and FT-IR spectrometry) confirm those obtained by techniques sensible to macroscopic properties of material (DMA, DSC), taking into account that no noticeable irradiation effect can be made evident inside the material. On the other hand, an irradiation carried out in air results in a superficial oxidation, due probably to the action of the air radiolysis products. The preliminary results of an ion irradiation followed by an in-situ HSF-SIMS analysis pointed out to a basic difference between the energy amount transferred by gamma photons and fast ions; the last ones being able to induce scissions of the nearby liaisons in the material. The second part of this work is concerned with the ion exchange resins of the type PS-DVB saturated in water and non-active ions, simulating real wastes, irradiated in the same conditions as the epoxyde resins. In contrast to the results on the last one, it appears that the irradiation of these materials results primarily in scissions of the functional groups on which the ions are attached. In addition to this finding it appears that the role of water as carrying outward the attached ions appears to be fundamental 175 refs.

  9. Armoring confined bubbles in concentrated colloidal suspensions

    Science.gov (United States)

    Yu, Yingxian; Khodaparast, Sepideh; Stone, Howard

    2016-11-01

    Encapsulation of a bubble with microparticles is known to significantly improve the stability of the bubble. This phenomenon has recently gained increasing attention due to its application in a variety of technologies such as foam stabilization, drug encapsulation and colloidosomes. Nevertheless, the production of such colloidal armored bubble with controlled size and particle coverage ratio is still a great challenge industrially. We study the coating process of a long air bubble by microparticles in a circular tube filled with a concentrated microparticles colloidal suspension. As the bubble proceeds in the suspension of particles, a monolayer of micro-particles forms on the interface of the bubble, which eventually results in a fully armored bubble. We investigate the phenomenon that triggers and controls the evolution of the particle accumulation on the bubble interface. Moreover, we examine the effects of the mean flow velocity, the size of the colloids and concentration of the suspension on the dynamics of the armored bubble. The results of this study can potentially be applied to production of particle-encapsulated bubbles, surface-cleaning techniques, and gas-assisted injection molding.

  10. Fabrication and manipulation of polymeric magnetic particles with magnetorheological fluid

    International Nuclear Information System (INIS)

    Rodríguez-López, Jaime; Shum, Ho Cheung; Elvira, Luis; Montero de Espinosa, Francisco; Weitz, David A.

    2013-01-01

    Polymeric magnetic microparticles have been created using a microfluidic device via ultraviolet (UV) polymerization of double emulsions, resulting in cores of magnetorheological (MR) fluids surrounded by polymeric shells. We demonstrate that the resultant particles can be manipulated magnetically to achieve triggered rupture of the capsules. This illustrates the great potential of our capsules for triggered release of active ingredients encapsulated in the polymeric magnetic microparticles. - Highlights: ► Polymeric microparticles encapsulating MR fluids have been fabricated. ► A double-emulsion-templated approach using microfluidic techniques has been used. ► The monodisperse microparticles obtained are easily manipulated under magnetic field. ► These microparticles have great potential for encapsulation-and-release applications.

  11. Structure and rheology of nanoparticle–polymer suspensions

    KAUST Repository

    Srivastava, Samanvaya

    2012-01-01

    Structure and rheology of oligomer-tethered nanoparticles suspended in low molecular weight polymeric host are investigated at various particle sizes and loadings. Strong curvature effects introduced by the small size of the nanoparticle cores are found to be important for understanding both the phase stability and rheology of the materials. Small angle X-ray scattering (SAXS) and transmission electron microscopy measurements indicate that PEG-SiO 2/PEG suspensions are more stable against phase separation and aggregation than expected from theory for interacting brushes. SAXS and rheology measurements also reveal that at high particle loadings, the stabilizing oligomer brush is significantly compressed and produces jamming in the suspensions. The jamming transition is accompanied by what appears to be a unique evolution in the transient suspension rheology, along with large increments in the zero-shear, Newtonian viscosity. The linear and nonlinear flow responses of the jammed suspensions are discussed in the framework of the Soft Glassy Rheology (SGR) model, which is shown to predict many features that are consistent with experimental observations, including a two-step relaxation following flow cessation and a facile method for determining the shear-thinning coefficient from linear viscoelastic measurements. Finally, we show that the small sizes of the particles have a significant effect on inter-particle interactions and rheology, leading to stronger deviations from expectations based on planar brushes and hard-sphere suspension theories. In particular, we find that in the high volume fraction limit, tethered nanoparticles interact in their host polymer through short-range forces, which are more analogous to those between soft particles than between spherical polymer brushes. © 2012 The Royal Society of Chemistry.

  12. Polymerized and functionalized triglycerides

    Science.gov (United States)

    Plant oils are useful sustainable raw materials for the development of new chemical products. As part of our research emphasis in sustainability and green polymer chemistry, we have explored a new method for polymerizing epoxidized triglycerides with the use of fluorosulfonic acid. Depending on the ...

  13. Polymerization by radiation. Application

    International Nuclear Information System (INIS)

    Romero, M.; Fernandez Miranda, J.

    1997-01-01

    Achieved results of the research work done in the field of radiation polymerization are summarized. Developing new chromatographic matrices, the radiation grafting of Glycidyl methacrylate on the surface of Low Density Polyethylene beads was studied. The dependence of both, the grafted degree and width of the grafted layer, with the radiation dose applied, is presented

  14. RAFT polymerization mediated bioconjugation strategies

    OpenAIRE

    Bulmuş, Volga

    2011-01-01

    This review aims to highlight the use of RAFT polymerization in the synthesis of polymer bioconjugates. It covers two main bioconjugation strategies using the RAFT process: (i) post-polymerization bioconjugations using pre-synthesized reactive polymers, and (ii) bioconjugations via in situ polymerization using biomolecule-modified monomers or chain transfer agents. © 2011 The Royal Society of Chemistry.

  15. An additive for a petroleum coke and water suspension

    Energy Technology Data Exchange (ETDEWEB)

    Khiguti, K.; Igarasi, T.; Isimura, Y.; Kharaguti, S.; Tsudzina, T.

    1983-03-04

    The patent covers an additive for a petroleum coke and watersuspension which contains soap of an aliphatic acid (AM) and or a salt of a maleic acid copolymer (SMK). The aliphatic acid soap is a salt of an alkaline earth metal of C6 to C22 aliphatic acid, an ammonium salt or a salt of a lower amine. The maleic acid copolymer is a salt (sodium, NH4) of a lower amine of a maleic anhydride copolymer with a copolymerizing vinyl additive. Capric acid, lauric acid, palmatic acid, aleic and other acids may be used as the aliphatic acid, while methylamine, trimethylamine, diethanolamine, morpholine and so on may be used as the lower amine salt. Ethylene, vinylchloride, methyl(meta)acrylate and so on are used as the polymerizing vinyl compound. The molar ratio of the maleic anhydride to the polymerizing vinyl compound is in a range from 1 to 1 to 1 to 10 (preferably 1 to 1 to 1 to 3). The maleic acid copolymer has a mean molecular mass within 1,000 to 5,000. The additive with the optimal composition contains a solvent, a thickener, an anticorrosion substance, anticoagulants, surfacants (PAV) and so on. A highly concentrated suspension of oil coke and water with a 50 to 75 percent concentration of powder form petroleum coke may be produced using the patented additive. Such a suspension is characterized by low viscosity, high stability and forms no foam during processing.

  16. Controlling active cabin suspensions in commercial vehicles

    NARCIS (Netherlands)

    Evers, W.J.E.; Besselink, I.J.M.; Teerhuis, A.P.; Knaap, van der A.C.M.; Nijmeijer, H.

    2009-01-01

    The field of automotive suspensions is changing. Semi-active and active suspensions are starting to become viable options for vehicle designers. Suspension design for commercial vehicles is especially interesting given its potential. An active cabin suspension for a heavy-duty truck is considered,

  17. "Point de suspension"

    CERN Multimedia

    2004-01-01

    CERN - Globe of Science and Innovation 20 and 21 October Acrobatics, mime, a cappella singing, projections of images, a magical setting... a host of different tools of a grandeur matching that of the Universe they relate. A camera makes a massive zoom out to reveal the multiple dimensions of Nature. Freeze the frame: half way between the infinitesimally small and the infinitesimally large, a man suspends his everyday life (hence the title "Point de Suspension", which refers to the three dots at the end of an uncompleted sentence) to take a glimpse of the place he occupies in the great history of the Universe. An unusual perspective on what it means to be a human being... This wondrous show in the Globe of Science and Innovation, specially created by the Miméscope* company for the official ceremony marking CERN's fiftieth anniversary, is a gift from the Government of the Republic and Canton of Geneva, which also wishes to share this moment of wonder with the local population. There will be three perfo...

  18. "Point de suspension"

    CERN Multimedia

    2004-01-01

    http://www.cern.ch/cern50/ CERN - Globe of Science and Innovation 20 and 21 October Acrobatics, mime, a cappella singing, projections of images, a magical setting... a host of different tools of a grandeur matching that of the Universe they relate. A camera makes a massive zoom out to reveal the multiple dimensions of Nature. Freeze the frame: half way between the infinitesimally small and the infinitesimally large, a man suspends his everyday life (hence the title "Point de Suspension", which refers to the three dots at the end of an uncompleted sentence) to take a glimpse of the place he occupies in the great history of the Universe. An unusual perspective on what it means to be a human being... This wondrous show in the Globe of Science and Innovation, specially created by the Miméscope* company for the official ceremony marking CERN's fiftieth anniversary, is a gift from the Government of the Republic and Canton of Geneva, which also wishes to share this moment of wonder with the local pop...

  19. "Point de suspension"

    CERN Multimedia

    2004-01-01

    CERN - Globe of Science and Innovation 20 and 21 October Acrobatics, mime, a cappella singing, projections of images, a magical setting... a host of different tools of a grandeur matching that of the Universe they relate. A camera makes a massive zoom out to reveal the multiple dimensions of Nature. Freeze the frame: half way between the infinitesimally small and the infinitesimally large, a man suspends his everyday life (hence the title "Point de Suspension", which refers to the three dots at the end of an uncompleted sentence) to take a glimpse of the place he occupies in the great history of the Universe. An unusual perspective on what it means to be a human being... This spectacle in the Globe of Science and Innovation, specially created by the Miméscope* company for the official ceremony marking CERN's fiftieth anniversary, is a gift from the Government of the Republic and Canton of Geneva, which also wishes to share this moment of wonder with the local population. There will be three performances for...

  20. The study of size and stability of n-butylcyanoacrylate nanocapsule suspensions encapsulating green grass fragrance

    Science.gov (United States)

    Zhu, G. Y.; Lin, C. T.; Chen, J. M.; Lei, D. M.; Zhu, G. X.

    2018-01-01

    Green grass fragrance has been widely used in many fields. However, fragrances are volatile compounds that do not last long. In order to prolong its odor, nanocapsules encapsulated green grass fragrance were prepared. The paper deals with the preparation of green grass fragrance nanocapsules by emulsion polymerization. N-butylcyanoacrylate (BCA) with excellent biocompatibility and biodegradability was used as encapsulant. The nanocapsule suspension systems were characterized and its stability was investigated. The physicochemical properties of polymeric nanocapsules (average diameter and polydispersity) were evaluated as a function of time to assess the system stability. The result showed that the system (containing 0.8% of green grass fragrance, with a polydispersity index (PDI) near 0.1 and an average diameter in the range of 20-30 nm) was an ideal state and relatively stable. Besides, the distinction of stability of three nanocapsule suspensions with different green grass fragrance content was also obvious from scanning electron microscopy (SEM).

  1. Preparation and evaluation of tilmicosin-loaded hydrogenated castor oil nanoparticle suspensions of different particle sizes.

    Science.gov (United States)

    Chen, Xiaojin; Wang, Ting; Lu, Mengmeng; Zhu, Luyan; Wang, Yan; Zhou, WenZhong

    2014-01-01

    Three tilmicosin-loaded hydrogenated castor oil nanoparticle (TMS-HCO-NP) suspensions of different particle sizes were prepared with different polyvinyl alcohol surfactant concentrations using a hot homogenization and ultrasonic technique. The in vitro release, in vitro antibacterial activity, mammalian cytotoxicity, acute toxicity in mice, and stability study were conducted to evaluate the characteristics of the suspensions. The in vitro tilmicosin release rate, antibacterial activity, mammalian cytotoxicity, acute toxicity in mice, and stability of the suspensions were evaluated. When prepared with polyvinyl alcohol concentrations of 0.2%, 1%, and 5%, the mean diameters of the nanoparticles in the three suspensions were 920±35 nm, 452±10 nm, and 151±4 nm, respectively. The three suspensions displayed biphasic release profiles similar to that of freeze-dried TMS-HCO-NP powders, with the exception of having a faster initial release. Moreover, suspensions of smaller-sized particles showed faster initial release, and lower minimum inhibitory concentrations and minimum bactericidal concentrations. Time-kill curves showed that within 12 hours, the suspension with the 151 nm particles had the most potent bactericidal activity, but later, the suspensions with larger-sized particles showed increased antibacterial activity. None of the three suspensions were cytotoxic at clinical dosage levels. At higher drug concentrations, all three suspensions showed similar concentration-dependent cytotoxicity. The suspension with the smallest-sized particle showed significantly more acute toxicity in mice, perhaps due to faster drug release. All three suspensions exhibited good stability at 4°C and at room temperature for at least 6 months. These results demonstrate that TMS-HCO-NP suspensions can be a promising formulation for tilmicosin, and that nanoparticle size can be an important consideration for formulation development.

  2. Radiation polymerization of tetrafluoroethylene

    International Nuclear Information System (INIS)

    Kadoi, H.; Lugao, A.B.; Oikawa, H.

    1984-01-01

    Tetrafluoroethylene (TFE) monomer was obtained by means of the pyrolysis of chlorodifluoromethane (R-22). The experiments were carried out in quartz tube with temperature between 700 0 and 800 0 C. The principal reaction of the pyrolysis is considered to be: 2CHClF2 ----> C 2 F 4 +2HCl. However, by-products such as HF, C 3 F 6 , C 2 HClF 4 , C 4 F 8 etc are also produced in the pyrolysis process. The conversions of R-22 varied from 30 to 50%, depending upon the temperature, pressure and flow rate of R-22 in the furnace. Finally the TFE monomer of purity higher than 99.98% was obtained by fractional distillation in low temperatures ranging from -10 0 to -30 0 C. The bulk polymerization of this monomer induced by γ-rays from 3000Ci cobalt-60 source was studied at various temperatures (room temperature, 0 0 , -23 0 and -78 0 C). The monomers were introduced into stainless steel vessels of 15 and 60 ml volume under vacuum. The control of polymerization reaction was rather hard at temperatures higher than -23 0 C due to the difficulty of removing the heat of reaction. However, the polymerization at -78 0 C was very easy to control. The white polymer particles were obtained in agglomerated state. The IR spectra of the polymers were consistent with those of commercial products. The melting points of samples were between 326 0 and 331 0 C. (Author) [pt

  3. ANALYSIS OF THERMAL AND AQUEOUS SUSPENSION STABILITIES OF CHITOSAN BASED NANOENCAPSULATED VITAMINS

    Directory of Open Access Journals (Sweden)

    Douglas de Britto

    Full Text Available The food nutritional content is reduced as result of vitamins degradation. In order to minimize such losses, the encapsulation technique into polymeric nanoparticles (NPs could offer an additional protection, extending the stability. The crosslinking formed by the ionic gelation process of chitosan and tripolyphosphate (Chi-TPP has been widely used as an encapsulating matrix for several chemical compounds. In this way, Chi-TPP was used for encapsulation of C, B9 and B12 vitamins. The stability of the vitamins in NPs was evaluated in aqueous suspension by UV-Visible spectroscopy under different conditions: stored in dark, light exposure and effect of oxygen bubbling. The results indicated that encapsulation had a positive effect in preserving the vitamins, mainly vitamin C. The encapsulation preserved 47% of the initial concentration of vitamin C by the tenth day and around 28% after 17 days. Conversely, in non-encapsulated controls (neutral and acidic medium the losses were higher, reaching 13% by the tenth day and almost 3% after 17 days of storage in both medium. When exposed to light and O2 the protection provided by the encapsulation was even greater. By thermogravimetric analysis, the pure and the encapsulated vitamins showed distinct thermal behavior confirming Chi-TPP as a potential encapsulation material.

  4. Bulk and interfacial stresses in suspensions of soft and hard colloids

    International Nuclear Information System (INIS)

    Truzzolillo, D; Roger, V; Dupas, C; Cipelletti, L; Mora, S

    2015-01-01

    We explore the influence of particle softness and internal structure on both the bulk and interfacial rheological properties of colloidal suspensions. We probe bulk stresses by conventional rheology, by measuring the flow curves, shear stress versus strain rate, for suspensions of soft, deformable microgel particles and suspensions of near hard-sphere-like silica particles. A similar behaviour is seen for both kinds of particles in suspensions at concentrations up to the random close packing volume fraction, in agreement with recent theoretical predictions for sub-micron colloids. Transient interfacial stresses are measured by analyzing the patterns formed by the interface between the suspensions and their solvent, due to a generalized Saffman–Taylor hydrodynamic instability. At odds with the bulk behaviour, we find that microgels and hard particle suspensions exhibit vastly different interfacial stress properties. We propose that this surprising behaviour results mainly from the difference in particle internal structure (polymeric network for microgels versus compact solid for the silica particles), rather than softness alone. (paper)

  5. The Research on Modeling and Simulation of TFE Polymerization Process

    Directory of Open Access Journals (Sweden)

    Jing Gao Sun

    2014-01-01

    Full Text Available PTFE (polytetrafluoroethylene is the fluorinated straight-chain polymer, made by the polymerization of tetrafluoroethylene monomer; it is used widely because of its excellent performance and can be obtained by the polymerization of body, solutions, suspensions, and emulsions. But only the last two are the main ways. This research paper makes simulation based on Polymer Plus. It uses the emulsion polymerization method at background to carry out a semibatch reactor system. Upon the actual production conditions, simulation process under the steady state conditions is used to analyze the effects of the changes on operating conditions; the corresponding dynamic model is created to analyze the impact of the changes of conditions on the entire system. Moreover, the amount of APS which plays an important part in this reaction is discussed for getting the most suitable amount of initiator. Because of less research work on this job, it is so difficult to find the related data from the literature. Therefore, this research will have a great significance for the process of the tetrafluoroethylene emulsion polymerization in the future.

  6. Radiation chemistry of polymeric system

    International Nuclear Information System (INIS)

    Machi, Sueo; Ishigaki, Isao

    1978-01-01

    Among wide application of radiation in the field of polymer chemistry, practices of polymerization, graft polymerization, bridging, etc. are introduced hereinafter. As for the radiation sources of radiation polymerization, in addition to the 60 Co-γ ray with long permeation distance which has been usually applied, electron beam accelerators with high energy, large current and high reliability have come to be produced, and the liquid phase polymerization by electron beam has attracted attention industrially. Concerning polymerizing reactions, explanations were given to electron beam polymerization under high dose rate, the polymerization in supercooling state or under high pressure, and emulsifying polymerization. As for radiation bridging, radiation is applied for the bridging of hydrogel, acceleration of bridging and improvement of radiation resistance. It is also utilized for reforming membranes by graft polymerization, and synthesis of polymers for medical use. Application of fixed enzymes in the medical field has been investigated by fixing various enzymes by low temperature γ-ray polymerization with glassy monomers such as HEMA. (Kobatake, H.)

  7. Ensemble-average versus suspension-scale Cauchy continuum-mechanical definitions of stress in polarized suspensions: Global homogenization of a dilute suspension of dipolar spherical particles

    International Nuclear Information System (INIS)

    Almog, Y.; Brenner, H.

    1999-01-01

    The macroscale rheological properties of a dilute suspension exposed to a uniform external field and composed of identical, rigid, inhomogeneous, dipolar, spherical particles dispersed in an incompressible Newtonian fluid and possessing the same mean density as the latter fluid are derived from knowledge of its microscale properties by applying a global ensemble-averaging technique. Each dipole, which is permanently embedded in the particle, is assumed to be generated by the presence of an inhomogeneous external body-force field in the particle interior resulting from the action of the uniform external field on an inhomogeneous distribution of interior matter. It is shown that although the ensemble-average stress tensor is symmetric, the suspension nevertheless behaves macroscopically as if it possessed an asymmetric stress tensor. This seeming contradiction can be traced to the fact that the average body force acting on the contents of any arbitrarily drawn volume lying in the interior of the suspension does not vanish despite the fact that each particle is 'neutrally buoyant'. That this force is not zero stems from the fact that some particles necessarily straddle the closed surface bounding that volume, and that the distribution of external body forces over the interiors of these particles is nonuniform. As such, that portion of the spherical particle lying outside of the surface enclosing the domain exerts a force on the remaining portion of the sphere lying within that domain. We then demonstrate that the natural macroscopic model, which is derived by equating the divergence of the suspension-scale stress appearing in that model to the ensemble-average external body-force field, and which predicts a symmetric stress tensor, is macroscopically deficient with respect to the more intuitive asymmetric stress model usually proposed by continuum mechanicians for such a suspension. It is shown that the latter, continuum-mechanical model recovers all the physically

  8. Packaging based on polymeric materials

    Directory of Open Access Journals (Sweden)

    Jovanović Slobodan M.

    2005-01-01

    Full Text Available In the past two years the consumption of common in the developed countries world wide (high tonnage polymers for packaging has approached a value of 50 wt.%. In the same period more than 50% of the packaging units on the world market were made of polymeric materials despite the fact that polymeric materials present 17 wt.% of all packaging materials. The basic properties of polymeric materials and their environmental and economical advantages, providing them such a position among packaging materials, are presented in this article. Recycling methods, as well as the development trends of polymeric packaging materials are also presented.

  9. Synthesis of magnetic polymeric microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Gervald, A Yu; Gritskova, Inessa A; Prokopov, Nikolai I [M.V. Lomonosov Moscow State Academy of Fine Chemical Technology, Moscow (Russian Federation)

    2010-05-13

    The key types of magnetic polymeric microspheres are considered. Methods of synthesis of different types of magnetic nanoparticles and of preparation of stable magnetic fluids on their basis are outlined. The overview of the methods for the manufacture of magnetic polymeric microspheres is presented. The effect of the synthesis conditions on the characteristics of magnetic polymeric microspheres such as the diameter and the particle size distribution and the content of magnetic material is discussed by particular examples. The application fields of magnetic polymeric microspheres are briefly surveyed.

  10. Synthesis of magnetic polymeric microspheres

    International Nuclear Information System (INIS)

    Gervald, A Yu; Gritskova, Inessa A; Prokopov, Nikolai I

    2010-01-01

    The key types of magnetic polymeric microspheres are considered. Methods of synthesis of different types of magnetic nanoparticles and of preparation of stable magnetic fluids on their basis are outlined. The overview of the methods for the manufacture of magnetic polymeric microspheres is presented. The effect of the synthesis conditions on the characteristics of magnetic polymeric microspheres such as the diameter and the particle size distribution and the content of magnetic material is discussed by particular examples. The application fields of magnetic polymeric microspheres are briefly surveyed.

  11. Uniform Suspension of the Clustered Triamcinolone Acetonide Particle

    Directory of Open Access Journals (Sweden)

    Masahiko Sugimoto

    2013-01-01

    Full Text Available Purpose. MaQaid (MaQ is a new triamcinolone acetonide commercialised in Japan to visualize the vitreous. Because MaQ is preservative-free, it has a lower risk of ocular toxicities. However, since MaQ is only available as a powder, it needs suspenssion. Suspension does not always result uniformally, which causes poor visibility. This study reports a new MaQ suspension for better visibility. Methods. After medium addition to a MaQ vial, various methods were used. These included the use of (1 vortex mixer, (2 two syringes and a three-way stopcock, and (3 ultrasonic washer. We calculated suspended MaQ concentration (. To evaluate the reproducibility, we estimated the coefficient of variance (CV, . We used this MaQ for pig eyes, and vitreous visualization was simulated. Subsequently, we used this MaQ suspension for humans. Results. MaQ suspensions were sucessfull, and the concentrations of single particles increased significantly (. The CV was 36.1% for the routine method and 9.03% ffor the new method. Administration of a suspended MaQ made it possible to clearly visualize the vitreous in both pig and human eyes. Conclusions. We devised new techniques for uniformal MaQ suspension. These new methods can compensate for the MaQ disadvantages and ensure a safety surgery.

  12. Multivectored Superficial Muscular Aponeurotic System Suspension for Facial Paralysis.

    Science.gov (United States)

    Leach, Garrison; Kurnik, Nicole; Joganic, Jessica; Joganic, Edward

    2017-06-01

    Facial paralysis is a devastating condition that may cause severe cosmetic and functional deformities. In this study we describe our technique for superficial muscular aponeurotic system (SMAS) suspension using barbed suture and compare the vectors of suspension in relation to the underlying musculature. This study also quantifies the improvements in postoperative symmetry using traditional anthropologic landmarks. The efficacy of this procedure for improving facial paralysis was determined by comparing anthropometric indices and using Procrustes distance between 4 groupings of homologous landmarks plotted on each patient's preoperative and postoperative photos. Geometric morphometrics was used to evaluate change in facial shape and improvement in symmetry postoperatively.To analyze the vector of suspension in relation to the underlying musculature, specific anthropologic landmarks were used to calculate the vector of the musculature in 3 facial hemispheres from cadaveric controls against the vector of repair in our patients. Ten patients were included in our study. Subjectively, great improvement in functional status was achieved. Geometric morphometric analysis demonstrated a statistically significant improvement in facial symmetry. Cadaveric dissection demonstrated that the suture should be placed in the SMAS in vectors parallel to the underlying musculature to achieve these results. There were no complications in our study to date. In conclusion, multivectored SMAS suture suspension is an effective method for restoring static suspension of the face after facial paralysis. This method has the benefit of producing quick, reliable results with improved function, low cost, and low morbidity.

  13. Active Control of Suspension Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    In this paper some recent research on active control of very long suspension bridges, is presented. The presentation is based on research work at Aalborg University, Denmark. The active control system is based on movable flaps attached to the bridge girder. Wind load on bridges with or without...... flaps attached to the girder is briefly presented. A simple active control system is discussed. Results from wind tunnel experiments with a bridge section show that flaps can be used effectively to control bridge girder vibrations. Flutter conditions for suspension bridges with and without flaps...

  14. Mechanocatalytic polymerization and cross-linking in a polymeric matrix

    NARCIS (Netherlands)

    Jakobs, R.T.M.; Ma, Shuang; Sijbesma, R.P.

    2013-01-01

    A latent olefin metathesis catalyst, bearing two polymeric NHC ligands, was embedded in a semicrystalline polymer matrix containing cyclic olefins. The catalyst was activated by straining the solid material under compression, resulting in polymerization and cross-linking reactions of the monomers in

  15. Studies on radiation-induced graft polymerization

    International Nuclear Information System (INIS)

    Omichi, Hideki

    1978-09-01

    Radiation-induced graft polymerization is used extensively to improve physical properties of polymers, but few processes are now commercialized. The reason for this is partly inadequate basic research on the reaction and partly the difficulty in developing the grafting process with large radiation source. Firstly, new techniques are proposed of studying kinetics of the graft polymerization in heterogeneous system. Based on the grafting yield, the molecular weight of graft chains, and the amount of radicals given by ESR and activation analysis, kinetic parameters are obtained and the reaction mechanism of grafting process is discussed. Secondly, the development of grafting process of poly (vinyl chloride)-butadiene is described. By study of the reaction, process design, construction and operation of the pilot plant, and economic analysis of the process, this process with 60 Co gamma ray sources is shown to be industrially promising. (author)

  16. RAFT polymerization and some of its applications.

    Science.gov (United States)

    Moad, Graeme; Rizzardo, Ezio; Thang, San H

    2013-08-01

    Reversible addition-fragmentation chain transfer (RAFT) is one of the most robust and versatile methods for controlling radical polymerization. With appropriate selection of the RAFT agent for the monomers and reaction conditions, it is applicable to the majority of monomers subject to radical polymerization. The process can be used in the synthesis of well-defined homo-, gradient, diblock, triblock, and star polymers and more complex architectures, which include microgels and polymer brushes. In this Focus Review we describe how the development of RAFT and RAFT application has been facilitated by the adoption of continuous flow techniques using tubular reactors and through the use of high-throughput methodology. Applications described include the use of RAFT in the preparation of polymers for optoelectronics, block copolymer therapeutics, and star polymer rheology control agents. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Four-Wheel Vehicle Suspension System

    Science.gov (United States)

    Bickler, Donald B.

    1990-01-01

    Four-wheel suspension system uses simple system of levers with no compliant components to provide three-point suspension of chassis of vehicle while maintaining four-point contact with uneven terrain. Provides stability against tipping of four-point rectangular base, without rocking contact to which rigid four-wheel frame susceptible. Similar to six-wheel suspension system described in "Articulated Suspension Without Springs" (NPO-17354).

  18. Heavy vehicle pitch dynamics and suspension tuning

    OpenAIRE

    Cao, Dongpu; Rakheja, Subhash; Su, Chun-Yi

    2008-01-01

    The influence of suspension tuning of passenger cars on bounce and pitch ride performance has been explored in a number of studies, while only minimal efforts have been made for establishing similar rules for heavy vehicles. This study aims to explore pitch dynamics and suspension tunings of a two-axle heavy vehicle with unconnected suspension, which could also provide valuable information for heavy vehicles with coupled suspensions. Based on a generalised pitch-plane model of a two-axle heav...

  19. Suspension-Firing of Biomass

    DEFF Research Database (Denmark)

    Shafique Bashir, Muhammad; Jensen, Peter Arendt; Frandsen, Flemming

    2012-01-01

    This paper is the second of two papers, describing probe measurements of deposit buildup and removal (shedding), conducted in a 350 MWth suspension-fired boiler, firing straw and wood. Investigations of deposit buildup and shedding have been made by use of an advanced online deposit probe and a s...

  20. Suspension-Firing of Biomass

    DEFF Research Database (Denmark)

    Bashir, Muhammad Shafique; Jensen, Peter Arendt; Frandsen, Flemming

    2012-01-01

    This paper is Part 1 in a series of two describing probe measurements of deposit build-up and removal (shedding) in a 350 MWth suspension boiler, firing straw and wood. The influence of fuel type (straw share in wood), probe exposure time, probe surface temperature (500, 550, and 600 °C), and flu...

  1. Nonlinear models of suspension bridges

    Czech Academy of Sciences Publication Activity Database

    Malík, Josef

    2006-01-01

    Roč. 321, č. 2 (2006), s. 828-850 ISSN 0022-247X Institutional research plan: CEZ:AV0Z30860518 Keywords : suspension bridges * principle of minimum energy Subject RIV: BA - General Mathematics Impact factor: 0.758, year: 2006

  2. Fracture in Kaolinite clay suspensions

    Science.gov (United States)

    Kosgodagan Acharige, Sebastien; Jerolmack, Douglas J.; Arratia, Paulo E.

    2017-11-01

    Clay minerals are involved in many natural (landslides, river channels) and industrial processes (ceramics, cosmetics, oil recovery). They are plate shaped charged colloids and exhibit different flow properties than simpler colloids when suspended in a liquid such as thixotropy and shear-banding. kaolinite platelets are non-swelling, meaning that the stacks formed by the platelets do not have water layers, and thus the suspension does not have a sol-gel transition. However, it has been shown that kaolinite suspensions possesses a non-zero yield stress even at low concentrations, indicating that the particles arrange themselves in a structure through attractive interactions. Here, we experimentally investigate the sedimentation of kaolinite suspensions in a Hele-Shaw cell. The sedimentation of these dilute suspensions can display solid behavior like fracture, revealed in cross-polarized light, which is linked to the failure of the weakly-bonded structure (typical yield stress 10-2 Pa). By changing the interaction potential of the particles (by sonication or introducing salts), we show through these sedimentation experiments, how the fracture pattern can be avoided. Research was sponsored by the Army Research Laboratory and was accomplished under Grant Number 569074.

  3. Numerical homogenization on approach for stokesian suspensions.

    Energy Technology Data Exchange (ETDEWEB)

    Haines, B. M.; Berlyand, L. V.; Karpeev, D. A. (Mathematics and Computer Science); (Department of Mathematics, Pennsylvania State Univ.)

    2012-01-20

    In this technical report we investigate efficient methods for numerical simulation of active suspensions. The prototypical system is a suspension of swimming bacteria in a Newtonian fluid. Rheological and other macroscopic properties of such suspensions can differ dramatically from the same properties of the suspending fluid alone or of suspensions of similar but inactive particles. Elongated bacteria, such as E. coli or B. subtilis, swim along their principal axis, propelling themselves with the help of flagella, attached at the anterior of the organism and pushing it forward in the manner of a propeller. They interact hydrodynamically with the surrounding fluid and, because of their asymmetrical shape, have the propensity to align with the local flow. This, along with the dipolar nature of bacteria (the two forces a bacterium exerts on a fluid - one due to self-propulsion and the other opposing drag - have equal magnitude and point in opposite directions), causes nearby bacteria to tend to align, resulting in a intermittent local ordering on the mesoscopic scale, which is between the microscopic scale of an individual bacterium and the macroscopic scale of the suspension (e.g., its container). The local ordering is sometimes called a collective mode or collective swimming. Thanks to self-propulsion, collective modes inject momentum into the fluid in a coherent way. This enhances the local strain rate without changing the macroscopic stress applied at the boundary of the container. The macroscopic effective viscosity of the suspension is defined roughly as the ratio of the applied stress to the bulk strain rate. If local alignment and therefore local strain-rate enhancement, are significant, the effective viscosity can be appreciably lower than that of the corresponding passive suspension or even of the surrounding fluid alone. Indeed, a sevenfold decrease in the effective viscosity was observed in experiments with B. subtilis. More generally, local collective

  4. Nuclear magnetic resonance applied to the study of polymeric nano composites

    International Nuclear Information System (INIS)

    Tavares, Maria Ines Bruno

    2011-01-01

    Polymers and nanoparticles based nano composites were prepared by intercalation by solution. The obtained nano composites were characterized mainly by the nuclear magnetic spectroscopy (NMR), applying the analysis of carbon-13 (polymeric matrix), silicon-29 (nanoparticle), and by determination of spin-lattice relaxation of the hydrogen nucleus (T 1 H) (polymeric matrix). The NMR have presented a promising technique in the characterization of the nano charge dispersion in the studied polymeric matrixes.

  5. 49 CFR 570.8 - Suspension systems.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 6 2010-10-01 2010-10-01 false Suspension systems. 570.8 Section 570.8 Transportation Other Regulations Relating to Transportation (Continued) NATIONAL HIGHWAY TRAFFIC SAFETY... Pounds or Less § 570.8 Suspension systems. (a) Suspension condition. Ball joint seals shall not be cut or...

  6. 49 CFR 570.61 - Suspension system.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 6 2010-10-01 2010-10-01 false Suspension system. 570.61 Section 570.61... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION VEHICLE IN USE INSPECTION STANDARDS Vehicles With GVWR of More Than 10,000 Pounds § 570.61 Suspension system. (a) Suspension condition. Ball joint seals shall not be cut...

  7. Thermal transport phenomena in nanoparticle suspensions

    International Nuclear Information System (INIS)

    Cardellini, Annalisa; Fasano, Matteo; Bozorg Bigdeli, Masoud; Chiavazzo, Eliodoro; Asinari, Pietro

    2016-01-01

    Nanoparticle suspensions in liquids have received great attention, as they may offer an approach to enhance thermophysical properties of base fluids. A good variety of applications in engineering and biomedicine has been investigated with the aim of exploiting the above potential. However, the multiscale nature of nanosuspensions raises several issues in defining a comprehensive modelling framework, incorporating relevant molecular details and much larger scale phenomena, such as particle aggregation and their dynamics. The objectives of the present topical review is to report and discuss the main heat and mass transport phenomena ruling macroscopic behaviour of nanosuspensions, arising from molecular details. Relevant experimental results are included and properly put in the context of recent observations and theoretical studies, which solved long-standing debates about thermophysical properties enhancement. Major transport phenomena are discussed and in-depth analysis is carried out for highlighting the role of geometrical (nanoparticle shape, size, aggregation, concentration), chemical (pH, surfactants, functionalization) and physical parameters (temperature, density). We finally overview several computational techniques available at different scales with the aim of drawing the attention on the need for truly multiscale predictive models. This may help the development of next-generation nanoparticle suspensions and their rational use in thermal applications. (topical review)

  8. Quadruple suspension design for Advanced LIGO

    International Nuclear Information System (INIS)

    Robertson, N A; Cagnoli, G; Crooks, D R M; Elliffe, E; Faller, J E; Fritschel, P; Gossler, S; Grant, A; Heptonstall, A; Hough, J; Lueck, H; Mittleman, R; Perreur-Lloyd, M; Plissi, M V; Rowan, S; Shoemaker, D H; Sneddon, P H; Strain, K A; Torrie, C I; Ward, H; Willems, P

    2002-01-01

    In this paper, we describe the conceptual design for the suspension system for the test masses for Advanced LIGO, the planned upgrade to LIGO, the US laser interferometric gravitational-wave observatory. The design is based on the triple pendulum design developed for GEO 600 - the German/UK interferometric gravitational wave detector. The GEO design incorporates fused silica fibres of circular cross-section attached to the fused silica mirror (test mass) in the lowest pendulum stage, in order to minimize the thermal noise from the pendulum modes. The damping of the low-frequency modes of the triple pendulum is achieved by using co-located sensors and actuators at the highest mass of the triple pendulum. Another feature of the design is that global control forces acting on the mirrors, used to maintain the output of the interferometer on a dark fringe, are applied via a triple reaction pendulum, so that these forces can be implemented via a seismically isolated platform. These techniques have been extended to meet the more stringent noise levels planned for in Advanced LIGO. In particular, the Advanced LIGO baseline design requires a quadruple pendulum with a final stage consisting of a 40 kg sapphire mirror, suspended on fused silica ribbons or fibres. The design is chosen to aim to reach a target noise contribution from the suspension corresponding to a displacement sensitivity of 10 -19 m Hz -1/2 at 10 Hz at each of the test masses

  9. PREDICTIVE CONTROL OF A BATCH POLYMERIZATION SYSTEM USING A FEEDFORWARD NEURAL NETWORK WITH ONLINE ADAPTATION BY GENETIC ALGORITHM

    Directory of Open Access Journals (Sweden)

    A. Cancelier

    Full Text Available Abstract This study used a predictive controller based on an empirical nonlinear model comprising a three-layer feedforward neural network for temperature control of the suspension polymerization process. In addition to the offline training technique, an algorithm was also analyzed for online adaptation of its parameters. For the offline training, the network was statically trained and the genetic algorithm technique was used in combination with the least squares method. For online training, the network was trained on a recurring basis and only the technique of genetic algorithms was used. In this case, only the weights and bias of the output layer neuron were modified, starting from the parameters obtained from the offline training. From the experimental results obtained in a pilot plant, a good performance was observed for the proposed control system, with superior performance for the control algorithm with online adaptation of the model, particularly with respect to the presence of off-set for the case of the fixed parameters model.

  10. Collaborative Research: Polymeric Multiferroics

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Shenqiang [Temple Univ., Philadelphia, PA (United States). College of Engineering

    2017-04-20

    The goal of this project is to investigate room temperature magnetism and magnetoelectric coupling of polymeric multiferroics. A new family of molecular charge-transfer crystals has been emerged as a fascinating opportunity for the development of all-organic electrics and spintronics due to its weak hyperfine interaction and low spin-orbit coupling; nevertheless, direct observations of room temperature magnetic spin ordering have yet to be accomplished in organic charge-transfer solids. Furthermore, room temperature magnetoelectric coupling effect hitherto known multiferroics, is anticipated in organic donor-acceptor complexes because of magnetic field effects on charge-transfer dipoles, yet this is also unexplored. The PI seeks to fundamental understanding of the control of organic crystals to demonstrate and explore room temperature multiferroicity. The experimental results have been verified through the theoretical modeling.

  11. Polymerization with freezing

    International Nuclear Information System (INIS)

    Ben-Naim, E; Krapivsky, P L

    2005-01-01

    Irreversible aggregation processes involving reactive and frozen clusters are investigated using the rate equation approach. In aggregation events, two clusters join irreversibly to form a larger cluster; additionally, reactive clusters may spontaneously freeze. Frozen clusters do not participate in merger events. Generally, freezing controls the nature of the aggregation process, as demonstrated by the final distribution of frozen clusters. The cluster mass distribution has a power-law tail, F k ∼k -γ , when the freezing process is sufficiently slow. Different exponents, γ = 1 and 3, are found for the constant and the product aggregation rates, respectively. For the latter case, the standard polymerization model, either no gels, or a single gel, or even multiple gels, may be produced

  12. Complex Macromolecular Architectures by Living Cationic Polymerization

    KAUST Repository

    Alghamdi, Reem D.

    2015-05-01

    Poly (vinyl ether)-based graft polymers have been synthesized by the combination of living cationic polymerization of vinyl ethers with other living or controlled/ living polymerization techniques (anionic and ATRP). The process involves the synthesis of well-defined homopolymers (PnBVE) and co/terpolymers [PnBVE-b-PCEVE-b-PSiDEGVE (ABC type) and PSiDEGVE-b-PnBVE-b-PSiDEGVE (CAC type)] by sequential living cationic polymerization of n-butyl vinyl ether (nBVE), 2-chloroethyl vinyl ether (CEVE) and tert-butyldimethylsilyl ethylene glycol vinyl ether (SiDEGVE), using mono-functional {[n-butoxyethyl acetate (nBEA)], [1-(2-chloroethoxy) ethyl acetate (CEEA)], [1-(2-(2-(t-butyldimethylsilyloxy)ethoxy) ethoxy) ethyl acetate (SiDEGEA)]} or di-functional [1,4-cyclohexanedimethanol di(1-ethyl acetate) (cHMDEA), (VEMOA)] initiators. The living cationic polymerizations of those monomers were conducted in hexane at -20 0C using Et3Al2Cl3 (catalyst) in the presence of 1 M AcOEt base.[1] The PCEVE segments of the synthesized block terpolymers were then used to react with living macroanions (PS-DPE-Li; poly styrene diphenyl ethylene lithium) to afford graft polymers. The quantitative desilylation of PSiDEGVE segments by n-Bu4N+F- in THF at 0 °C led to graft co- and terpolymers in which the polyalcohol is the outer block. These co-/terpolymers were subsequently subjected to “grafting-from” reactions by atom transfer radical polymerization (ATRP) of styrene to afford more complex macromolecular architectures. The base assisted living cationic polymerization of vinyl ethers were also used to synthesize well-defined α-hydroxyl polyvinylether (PnBVE-OH). The resulting polymers were then modified into an ATRP macro-initiator for the synthesis of well-defined block copolymers (PnBVE-b-PS). Bifunctional PnBVE with terminal malonate groups was also synthesized and used as a precursor for more complex architectures such as H-shaped block copolymer by “grafting-from” or

  13. Suspensions with reduced violin string modes

    International Nuclear Information System (INIS)

    Lee, B H; Ju, L; Blair, D G

    2006-01-01

    We discuss the possibility of significantly reducing the number and Q-factor of violin string modes in the mirror suspension. Simulations of a bar-flexure suspension and an orthogonal ribbon have shown a reduction in the number of violin string modes when compared to a normal ribbon suspension. By calculating the expected suspension thermal noise, we find that the orthogonal ribbon provides a promising suspension alternative. A lower number of violin modes oscillating in the direction of the laser and a reduction in violin mode peak values of at least 23dB can be achieved with a slight increase in thermal noise above 40Hz

  14. Suspensions with reduced violin string modes

    Energy Technology Data Exchange (ETDEWEB)

    Lee, B H; Ju, L; Blair, D G [School of Physics, University of Western Australia, Crawley 6009, WA (Australia)

    2006-03-02

    We discuss the possibility of significantly reducing the number and Q-factor of violin string modes in the mirror suspension. Simulations of a bar-flexure suspension and an orthogonal ribbon have shown a reduction in the number of violin string modes when compared to a normal ribbon suspension. By calculating the expected suspension thermal noise, we find that the orthogonal ribbon provides a promising suspension alternative. A lower number of violin modes oscillating in the direction of the laser and a reduction in violin mode peak values of at least 23dB can be achieved with a slight increase in thermal noise above 40Hz.

  15. Polymeric micelles for drug targeting.

    Science.gov (United States)

    Mahmud, Abdullah; Xiong, Xiao-Bing; Aliabadi, Hamidreza Montazeri; Lavasanifar, Afsaneh

    2007-11-01

    Polymeric micelles are nano-delivery systems formed through self-assembly of amphiphilic block copolymers in an aqueous environment. The nanoscopic dimension, stealth properties induced by the hydrophilic polymeric brush on the micellar surface, capacity for stabilized encapsulation of hydrophobic drugs offered by the hydrophobic and rigid micellar core, and finally a possibility for the chemical manipulation of the core/shell structure have made polymeric micelles one of the most promising carriers for drug targeting. To date, three generations of polymeric micellar delivery systems, i.e. polymeric micelles for passive, active and multifunctional drug targeting, have arisen from research efforts, with each subsequent generation displaying greater specificity for the diseased tissue and/or targeting efficiency. The present manuscript aims to review the research efforts made for the development of each generation and provide an assessment on the overall success of polymeric micellar delivery system in drug targeting. The emphasis is placed on the design and development of ligand modified, stimuli responsive and multifunctional polymeric micelles for drug targeting.

  16. Gyrospun antimicrobial nanoparticle loaded fibrous polymeric filters

    Energy Technology Data Exchange (ETDEWEB)

    Eranka Illangakoon, U.; Mahalingam, S.; Wang, K. [Department of Mechanical Engineering, University College London, London WC1E 7JE (United Kingdom); Cheong, Y.-K. [School of Engineering and Technology, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); Canales, E. [Department of Civil, Environmental and Geomatic Engineering, University College London, London WC1E 7JE (United Kingdom); Ren, G.G. [School of Engineering and Technology, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); Cloutman-Green, E. [Department of Microbiology, Virology, and Infection Prevention Control, Great Ormond Street Hospital NHS Foundation Trust, London WCIN 3JH (United Kingdom); Edirisinghe, M., E-mail: m.edirisinghe@ucl.ac.uk [Department of Mechanical Engineering, University College London, London WC1E 7JE (United Kingdom); Ciric, L. [Department of Civil, Environmental and Geomatic Engineering, University College London, London WC1E 7JE (United Kingdom)

    2017-05-01

    A one step approach to prepare hybrid nanoparticle embedded polymer fibres using pressurised gyration is presented. Two types of novel antimicrobial nanoparticles and poly(methylmethacrylate) polymer were used in this work. X-ray diffraction analysis of the nanoparticles revealed Ag, Cu and W are the main elements present in them. The concentration of the polymer solution and the nanoparticle concentration had a significant influence on the fibre diameter, pore size and morphology. Fibres with a diameter in the range of 6–20 μm were spun using 20 wt% polymer solutions containing 0.1, 0.25 and 0.5 wt% nanoparticles under 0.3 MPa working pressure and a rotational speed of 36,000 rpm. Continuous, bead-free fibre morphologies were obtained for each case. The pore size in the fibres varied between 36 and 300 nm. Successful incorporation of the nanoparticles in polymer fibres was confirmed by energy dispersive x-ray analysis. The fibres were also gyrospun on to metallic discs to prepare filters which were tested for their antibacterial activity on a suspension of Pseudomonas aeruginosa. Nanoparticle loaded fibres showed higher antibacterial efficacy than pure poly(methylmethacrylate) fibres. - Highlights: • Nanoparticles containing Ag, Cu and W were studied for antimicrobial activity. • Hybrid nanoparticle-polymeric fibres were prepared using pressurised gyration. • Fibre characteristics were tailored using material and forming process variables. • Nanoparticle loaded fibre mats show higher antibacterial efficacy.

  17. A qualitative chemometric study of resin composite polymerization

    Directory of Open Access Journals (Sweden)

    Regina Ferraz Mendes

    2008-01-01

    Full Text Available Objective: An experiment was carried out to assess the effect produced by different polymerization techniques on resin composite color after it has been immersed in coffee. Methods: Samples were manufactured using TPH Spectrum composite. It was polymerized for 10 or 40 seconds, with the light tip at one or zero millimeters from the resin surface, and afterwards the samples were immersed in coffee for 24 hours or 7 days. Ten different evaluators classified the samples according to their degree of staining. Results: The samples that were polymerized for 10 seconds were more susceptible to staining than the ones polymerized by 40 seconds. Samples immersed in coffee for 7 days were more susceptible to staining than the ones immersed for 24 hours. Conclusion: The variables polymerization time and immersion time were determinant in the staining susceptibility of the studied composite by coffee. However, there was no significant difference, irrespective of whether the resin was polymerized 10 or zero millimeters away from the resin surface.

  18. Particle Suspension Mechanisms - Supplemental Material

    Energy Technology Data Exchange (ETDEWEB)

    Dillon, M B

    2011-03-03

    This supplemental material provides a brief introduction to particle suspension mechanisms that cause exfoliated skin cells to become and remain airborne. The material presented here provides additional context to the primary manuscript and serves as background for designing possible future studies to assess the impact of skin cells as a source of infectious aerosols. This introduction is not intended to be comprehensive and interested readers are encouraged to consult the references cited.

  19. Robust Tensioned Kevlar Suspension Design

    Science.gov (United States)

    Young, Joseph B.; Naylor, Bret J.; Holmes, Warren A.

    2012-01-01

    One common but challenging problem in cryogenic engineering is to produce a mount that has excellent thermal isolation but is also rigid. Such mounts can be achieved by suspending the load from a network of fibers or strings held in tension. Kevlar fibers are often used for this purpose owing to their high strength and low thermal conductivity. A suite of compact design elements has been developed to improve the reliability of suspension systems made of Kevlar.

  20. Tricalcium Phosphate Containing Sodium Hexametaphosphate as Polymer Suspension Stabilizer

    Directory of Open Access Journals (Sweden)

    K. Rahbar Shamskar

    2008-12-01

    Full Text Available Tricalcium phosphate as hydroxyapatite is used as a suspension stabilizer in styrene polymerization process. Particle size of TCP plays an essential role in the particles’ size distribution and geometrical form of polystyrene products. As the particle size of TCP is reduced, there will be much better chance to engulf the styrene particles. The higher the number of TCP particles surrounding each styrene particle, the lesser will be their tendency to form a large particle after collision. Therefore, there will be higher percentages of spherical polystyrene with small particle size and narrower size distribution in the product. Experimental results have indicated that the addition of sodium hexametaphosphate (SHMP to the reaction mixture of lime and phosphoric acid, after drying the product by spray dryer, lead to decrease the size of TCP particles from ca. 5 μm (without SHMP to ca. 1.5 μm (with SHMP. In this study, the role of TCP containing SHMP as polymer suspension stabilizer and consequently the beads size of polystyrene is investigated in laboratory scale. The results show that despite addition of SHMP to the reaction mixture of lime and phosphoric acid decreases the TCP particles size and the mean bead size of the product of polystyrene become larger than the product prepared by TCP without SHMP.

  1. Polymorphism in Bacterial Flagella Suspensions

    Science.gov (United States)

    Schwenger, Walter J.

    Bacterial flagella are a type of biological polymer studied for its role in bacterial motility and the polymorphic transitions undertaken to facilitate the run and tumble behavior. The naturally rigid, helical shape of flagella gives rise to novel colloidal dynamics and material properties. This thesis studies methods in which the shape of bacterial flagella can be controlled using in vitro methods and the changes the shape of the flagella have on both single particle dynamics and bulk material properties. We observe individual flagellum in both the dilute and semidilute regimes to observe the effects of solvent condition on the shape of the filament as well as the effect the filament morphology has on reptation through a network of flagella. In addition, we present rheological measurements showing how the shape of filaments effects the bulk material properties of flagellar suspensions. We find that the individual particle dynamics in suspensions of flagella can vary with geometry from needing to reptate linearly via rotation for helical filaments to the prevention of long range diffusion for block copolymer filaments. Similarly, for bulk material properties of flagella suspensions, helical geometries show a dramatic enhancement in elasticity over straight filaments while block copolymers form an elastic gel without the aid of crosslinking agents.

  2. Organometallic Polymeric Conductors

    Science.gov (United States)

    Youngs, Wiley J.

    1997-01-01

    For aerospace applications, the use of polymers can result in tremendous weight savings over metals. Suitable polymeric materials for some applications like EMI shielding, spacecraft grounding, and charge dissipation must combine high electrical conductivity with long-term environmental stability, good processability, and good mechanical properties. Recently, other investigators have reported hybrid films made from an electrically conductive polymer combined with insulating polymers. In all of these instances, the films were prepared by infiltrating an insulating polymer with a precursor for a conductive polymer (either polypyrrole or polythiophene), and oxidatively polymerizing the precursor in situ. The resulting composite films have good electrical conductivity, while overcoming the brittleness inherent in most conductive polymers. Many aerospace applications require a combination of properties. Thus, hybrid films made from polyimides or other engineering resins are of primary interest, but only if conductivities on the same order as those obtained with a polystyrene base could be obtained. Hence, a series of experiments was performed to optimize the conductivity of polyimide-based composite films. The polyimide base chosen for this study was Kapton. 3-MethylThiophene (3MT) was used for the conductive phase. Three processing variables were identified for producing these composite films, namely time, temperature, and oxidant concentration for the in situ oxidation. Statistically designed experiments were used to examine the effects of these variables and synergistic/interactive effects among variables on the electrical conductivity and mechanical strength of the films. Multiple linear regression analysis of the tensile data revealed that temperature and time have the greatest effect on maximum stress. The response surface of maximum stress vs. temperature and time (for oxidant concentration at 1.2 M) is shown. Conductivity of the composite films was measured for

  3. Impact of lysozyme on stability mechanism of nanozirconia aqueous suspension

    Energy Technology Data Exchange (ETDEWEB)

    Szewczuk-Karpisz, Katarzyna, E-mail: k.szewczuk-karpisz@wp.pl; Wiśniewska, Małgorzata

    2016-08-30

    Highlights: • Adsorption and stabilization-destabilization properties of lysozyme (LSZ) in the nanozirconia-biopolymer solution system were determined. • The stability measurements were performed using turbidimetric method. • Lysozyme macromolecules undergo adsorption on the ZrO{sub 2} surface under electrostatic adsorbent-adsorbate attraction, i.e. at pH 6 and 9. • The biopolymer adsorption impact on the zirconia stability varies at different pH values. - Abstract: The effect of lysozyme (LSZ) presence on the zirconium(IV) oxide (ZrO{sub 2}) aqueous suspension stability was examined. The applied zirconia contains mesopores (with a diameter about 30 nm) and its mean particle size is about 100 nm. To determine the stability mechanism of ZrO{sub 2} suspension in the biopolymer presence, the adsorption and electrokinetic (surface charge density and zeta potential) measurements were performed in the pH range 3–10. The lysozyme adsorption on the nanozirconia surface proceeds mainly through electrostatic forces. Under solid-polymer repulsion conditions, there is no adsorption of lysozyme (pH < 6, C{sub NaCl} 0.01 mol/dm{sup 3}). The increase of solution ionic strength to 0.2 mol/dm{sup 3} causes screening of unfavourable forces and biopolymer adsorption becomes possible. The LSZ addition to the ZrO{sub 2} suspension influences its stability. At pH 3, 4.6 and 7.6, slight improvement of the system stability was obtained. In turn, at pH 9 considerable destabilization of nanozirconia particles covered by polymeric layers occurs.

  4. Dispersion of nanoparticulate suspensions using self-assembled surfactant aggregates

    Science.gov (United States)

    Singh, Pankaj Kumar

    The dispersion of particles is critical for several industrial applications such as paints, inks, coatings, and cosmetics. Several emerging applications such as abrasives for precision polishing, and drug delivery systems are increasingly relying on nanoparticulates to achieve the desired performance. In the case of nanoparticles, the dispersion becomes more challenging because of the lack of fundamental understanding of dispersant adsorption and interparticle force prediction. Additionally, many of these processes use severe processing environments such as high normal forces (>100 mN/m), high shear forces (>10,000 s -1), and high ionic strengths (>0.1 M). Under such processing conditions, traditionally used dispersants based on electrostatics, and steric force repulsion mechanism may not be adequate. Hence, the development of optimally performing dispersants requires a fundamental understanding of the dispersion mechanism at the atomic/molecular scale. This study explores the use of self-assembled surfactant aggregates at the solid-liquid interface for dispersing nanoparticles in severe processing environments. Surfactant molecules can provide a feasible alternative to polymeric or inorganic dispersants for stabilizing ultrafine particles. The barrier to aggregation in the presence of surfactant molecules was measured using atomic force microscopy. The barrier heights correlated to suspension stability. To understand the mechanism for nanoparticulate suspension stability in the presence of surfactant films, the interface was characterized using zeta potential, contact angle, adsorption, and FT-IR (adsorbed surfactant film structure measurements). The effect of solution conditions such as pH and ionic strength on the suspension stability, and the self-assembled surfactant films was also investigated. It was determined that a transition from a random to an ordered orientation of the surfactant molecules at the interface was responsible for stability of

  5. Nifedipine-loaded polymeric nanocapsules: validation of a stability-indicating HPLC method to evaluate the drug entrapment efficiency and in vitro release profiles.

    Science.gov (United States)

    Granada, Andréa; Tagliari, Monika Piazzon; Soldi, Valdir; Silva, Marcos António Segatto; Zanetti-Ramos, Betina Ghiel; Fernandes, Daniel; Stulzer, Hellen Karine

    2013-01-01

    A simple stability-indicating analytical method was developed and validated to quantify nifedipine in polymeric nanocapsule suspensions; an in vitro drug release study was then carried out. The analysis was performed using an RP C18 column, UV-Vis detection at 262 nm, and methanol-water (70 + 30, v/v) mobile phase at a flow rate of 1.2 mL/min. The method was validated in terms of specificity, linearity and range, LOQ, accuracy, precision, and robustness. The results obtained were within the acceptable ranges. The nanocapsules, made of poly(epsilon-caprolactone), were prepared by the solvent displacement technique and showed high entrapment efficiency. The entrapment efficiency was 97.6 and 98.2% for the nifedipine-loaded polymeric nanocapsules prepared from polyvinyl alcohol (PVA) and Pluronic F68 (PF68), respectively. The particle size and zeta potential of nanocapsules were found to be influenced by the nature of the stabilizer used. The mean diameter and zeta potential for nanocapsules with PVA and PF68 were 290.9 and 179.9 nm, and -17.7 mV and -32.7 mV, respectively. The two formulations prepared showed a drug release of up to 70% over 4 days. This behavior indicates the viability of this drug delivery system for use as a controlled-release system.

  6. Planar elongation of soft polymeric networks

    DEFF Research Database (Denmark)

    Jensen, Mette Krog; Hassager, Ole; Rasmussen, Henrik K.

    2010-01-01

    . To validate this new technique, soft polymeric networks of poly(propylene oxide) (PPO) were investigated during deformation. Particle tracking and video recording were used to detect to what extent the imposed strain rate and the sample perimeter remained constant. It was observed that, by using...... difference deviated more from the classical prediction due to the dynamic structures in the material. A modified Lodge model using characteristic parameters from linear viscoelastic measurements gave very good stress predictions at all Deborah numbers used in the quasi-linear regime....

  7. Optical Fiber Sensors Based on Polymeric Sensitive Coatings

    Directory of Open Access Journals (Sweden)

    Pedro J. Rivero

    2018-03-01

    Full Text Available Polymer technology is one of the fastest growing fields of contemporary research due to the possibility of using a wide variety of synthetic chemical routes for obtaining a polymeric network with a well-defined structure, resulting in materials with outstanding macroscopic properties. Surface engineering techniques based on the implementation of polymeric structures can be used as an interesting tool for the design of materials with functional properties. In this sense, the use of fabrication techniques for the design of nanostructured polymeric coatings is showing an important growth due to the intrinsic advantages of controlling the structure at a nanoscale level because physical, chemical, or optical properties can be considerably improved in comparison with the bulk materials. In addition, the presence of these sensitive polymeric coatings on optical fiber is a hot topic in the scientific community for its implementation in different market niches because a wide variety of parameters can be perfectly measured with a high selectivity, sensitivity, and fast response time. In this work, the two main roles that a polymeric sensitive matrix can play on an optical fiber for sensing applications are evaluated. In a first section, the polymers are used as a solid support for the immobilization of specific sensitive element, whereas in the second section the polymeric matrix is used as the chemical transducer itself. Additionally, potential applications of the optical fiber sensors in fields as diverse as biology, chemistry, engineering, environmental, industry or medicine will be presented in concordance with these two main roles of the polymeric sensitive matrices.

  8. Adjustment of a rapid method for quantification of Fusarium spp. spore suspensions in plant pathology.

    Science.gov (United States)

    Caligiore-Gei, Pablo F; Valdez, Jorge G

    2015-01-01

    The use of a Neubauer chamber is a broadly employed method when cell suspensions need to be quantified. However, this technique may take a long time and needs trained personnel. Spectrophotometry has proved to be a rapid, simple and accurate method to estimate the concentration of spore suspensions of isolates of the genus Fusarium. In this work we present a linear formula to relate absorbance measurements at 530nm with the number of microconidia/ml in a suspension. Copyright © 2014 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

  9. Quenching of Particle-Gas Combustible Mixtures Using Electric Particulate Suspension (EPS) and Dispersion Methods

    Science.gov (United States)

    Colver, Gerald M.; Goroshin, Samuel; Lee, John H. S.

    2001-01-01

    A cooperative study is being carried out between Iowa State University and McGill University. The new study concerns wall and particle quenching effects in particle-gas mixtures. The primary objective is to measure and interpret flame quenching distances, flammability limits, and burning velocities in particulate suspensions. A secondary objective is to measure particle slip velocities and particle velocity distribution as these influence flame propagation. Two suspension techniques will be utilized and compared: (1) electric particle suspension/EPS; and (2) flow dispersion. Microgravity tests will permit testing of larger particles and higher and more uniform dust concentrations than is possible in normal gravity.

  10. De fysica van polymere materialen

    NARCIS (Netherlands)

    Struik, L.C.E.

    1987-01-01

    Rede, uitgesproken ter gelegenheid van de aanvaarding van het ambt van buitengewoon hoogleraar in de fysica van polymere materialen aan de Universitelt Twente op donderdag 22 januarì 1987 door Dr.lr. L.C.E. Struik.

  11. Phosphazene-promoted anionic polymerization

    KAUST Repository

    Zhao, Junpeng; Hadjichristidis, Nikolaos; Gnanou, Yves

    2014-01-01

    .e. in situ activation (of initiating sites) and polymerization, and summarize the applications of such a mechanism on macromolecular engineering toward functionalized polymers, block copolymers and complex macromolecular architectures.

  12. Pulsed-laser polymerization in compartmentalized liquids. 1. Polymerization in vesicles

    NARCIS (Netherlands)

    Jung, M.; Casteren, van I.A.; Monteiro, M.J.; Herk, van A.M.; German, A.L.

    2000-01-01

    Polymerization in vesicles is a novel type of polymerization in heterogeneous media, leading to parachute-like vesicle-polymer hybrid morphologies. To explore the kinetics of vesicle polymerizations and to learn more about the actual locus of polymerization we applied the pulsed-laser polymerization

  13. Electrohydrodynamics of suspension of liquid drops in AC fields

    Science.gov (United States)

    Abdul Halim, Md.; Esmaeeli, Asghar

    2012-11-01

    Manipulation of liquid drops by an externally applied electric field is currently the focus of increased attention because of its relevance in a broad range of industrial processes. The effect of a uniform DC electric field on a solitary drop is well studied; however, less is know about the impact of electric field on suspension of liquid drops, and very little information is available on the impact of AC field on a single or a suspension of drops. Here we report the results of Direct Numerical Simulations of electrohydrodynamics of suspension of liquid drops. The governing equations are solved using a front tracking/finite difference technique, in conjunction with Taylor's leaky dielectric model. The imposed electric potential comprises of two parts, a time-independent base and a time-dependent part. The goal is to explore the relative importance of these two components in setting the statistically steady state behavior of the suspension. To this end, we report the results of three sets of simulations, where (i) the time-dependent part act as a perturbation on the base potential, (ii) the two components are of the same order, and (iii) the time-dependent part is much larger than the base potential. The problem is studied as a function of the governing nondimensional parameters.

  14. Optical limiting in suspension of detonation nanodiamonds in engine oil

    Science.gov (United States)

    Mikheev, Konstantin G.; Krivenkov, Roman Yu.; Mogileva, Tatyana N.; Puzyr, Alexey P.; Bondar, Vladimir S.; Bulatov, Denis L.; Mikheev, Gennady M.

    2017-07-01

    The optical limiting (OL) of detonation nanodiamond (DND) suspensions in engine oil was studied at a temperature range of 20°C to 100°C. Oil suspensions were prepared on the basis of the DNDs with an average nanoparticle cluster size in hydrosols (Daver) of 50 and 110 nm. Raman spectroscopy was used to characterize the samples. The OL investigation was carried out by the z-scan technique. The fundamental (1064 nm) and second (532 nm) harmonic radiations of YAG:Nd3+ laser with passive Q-switching as an excitation source were used. The OL thresholds for both suspensions at 532 and 1064 nm were determined. It is shown that a decrease in the average nanoparticle cluster size as well as an increase of the wavelength of the incident radiation leads to the OL threshold increase. It is established that the OL performance is not influenced by increasing the temperature from 20°C to 100°C. The results obtained show the possibility of using the DNDs suspensions in engine oil as an optical limiter in a wide temperature range.

  15. Plasma polymerized high energy density dielectric films for capacitors

    Science.gov (United States)

    Yamagishi, F. G.

    1983-01-01

    High energy density polymeric dielectric films were prepared by plasma polymerization of a variety of gaseous monomers. This technique gives thin, reproducible, pinhole free, conformable, adherent, and insoluble coatings and overcomes the processing problems found in the preparation of thin films with bulk polymers. Thus, devices are prepared completely in a vacuum environment. The plasma polymerized films prepared all showed dielectric strengths of greater than 1000 kV/cm and in some cases values of greater than 4000 kV/cm were observed. The dielectric loss of all films was generally less than 1% at frequencies below 10 kHz, but this value increased at higher frequencies. All films were self healing. The dielectric strength was a function of the polymerization technique, whereas the dielectric constant varied with the structure of the starting material. Because of the thin films used (thickness in the submicron range) surface smoothness of the metal electrodes was found to be critical in obtaining high dielectric strengths. High dielectric strength graft copolymers were also prepared. Plasma polymerized ethane was found to be thermally stable up to 150 C in the presence of air and 250 C in the absence of air. No glass transitions were observed for this material.

  16. Polyolefin nanocomposites in situ polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Galland, Griselda Barrera; Fim, Fabiana de C.; Milani, Marceo A.; Silva, Silene P. da; Forest, Tadeu; Radaelli, Gislaine, E-mail: griselda.barrera@ufrgs.br [Universidade Federal do Rio Grande de Sul - UFRGS, Porto Alegre, RS (Brazil); Basso, Nara R.S. [Pontificia Universidade Catolica do Rio Grande do Sul, Porto Alegre, RS (Brazil); Quijada, Raul [Universidad de Chile, Santiago (Chile)

    2011-07-01

    Polyethylene and polypropylene nanocomposites using grapheme nanosheets and treated chrysotile have been synthesized by in situ polymerization using metallocene catalysts. The fillers have been submitted to acid, thermal and/ou ultrasound treatments before to introduce them into the polymerization reactor. A complete characterization of the fillers has been done. The nanocomposites have been characterized by SEM, TEM, DRX and AFM. The thermal, mechanic -dynamic, mechanical and electrical properties of the nanocomposites are discussed. (author)

  17. Polyolefin nanocomposites in situ polymerization

    International Nuclear Information System (INIS)

    Galland, Griselda Barrera; Fim, Fabiana de C.; Milani, Marceo A.; Silva, Silene P. da; Forest, Tadeu; Radaelli, Gislaine; Basso, Nara R.S.; Quijada, Raul

    2011-01-01

    Polyethylene and polypropylene nanocomposites using grapheme nanosheets and treated chrysotile have been synthesized by in situ polymerization using metallocene catalysts. The fillers have been submitted to acid, thermal and/ou ultrasound treatments before to introduce them into the polymerization reactor. A complete characterization of the fillers has been done. The nanocomposites have been characterized by SEM, TEM, DRX and AFM. The thermal, mechanic -dynamic, mechanical and electrical properties of the nanocomposites are discussed. (author)

  18. Electroactivity in Polymeric Materials

    CERN Document Server

    2012-01-01

    Electroactivity in Polymeric Materials provides an in-depth view of the theory of electroactivity and explores exactly how and why various electroactive phenomena occur. The book explains the theory behind electroactive bending (including ion-polymer-metal-composites –IPMCs), dielectric elastomers, electroactive contraction, and electroactive contraction-expansion cycles.  The book also balances theory with applications – how electroactivity can be used – drawing inspiration from the manmade mechanical world and the natural world around us.  This book captures: A complete introduction to electroactive materials including examples and recent developments The theory and applications of numerous topics like electroactive bending of dielectric elastomers and electroactive contraction and expansion New topics, such as biomimetic applications and energy harvesting This is a must-read within the electroactive community, particularly for professionals and graduate students who are interested in the ...

  19. Size, velocity, and concentration in suspension measurements of spherical droplets and cylindrical jets.

    Science.gov (United States)

    Onofri, F; Bergougnoux, L; Firpo, J L; Misguich-Ripault, J

    1999-07-20

    The principle of an optical technique for simultaneous velocity, size, and concentration in suspension measurements of spherical droplets and cylindrical jets is proposed. This technique is based on phase Doppler anemometry working in the dual burst technique configuration. The particle size and velocity are deduced from the reflected signal phase and frequency, whereas the amplitude ratio between the refracted and the reflected signals is used for measuring the concentration of small scatterers inside the particles. Numerical simulations, based on geometrical optics and a Monte Carlo model, and an experimental validation test on cylindrical jets made of various suspensions, are used to validate the principle of the proposed technique. It is believed that this new technique could be useful in investigating processes in which liquid suspensions are sprayed for surface coating, drying, or combustion applications.

  20. Novel polymeric biochips for enhanced detection of infectious diseases

    CERN Document Server

    Hosseini, Samira

    2016-01-01

    This book focuses on the creation and development of polymeric platforms (different compositions) from a specific polymer system. This system can be used as an adaptive technique for producing sensitive analytical devices, or for simple integration into existing bioanalytical tools in order to enhance the detection signal.

  1. Polymeric microsieves via phase separation microfabrication: Process and design optimization

    NARCIS (Netherlands)

    Bikel, M.; Culfaz, P.Z.; Bolhuis-Versteeg, Lydia A.M.; Perez, J. Garduno; Lammertink, Rob G.H.; Wessling, Matthias

    2010-01-01

    Phase separation microfabrication (PSμF) is a fabrication method that allows the preparation of membranes having micropattern surface topologies. PSμF has been successfully used for manufacturing polymeric microsieves. The technique benefits from the vertical shrinkage of polymer solutions to ensure

  2. Selective enzymatic degradation of self-assembled particles from amphiphilic block copolymers obtained by the combination of N-carboxyanhydride and nitroxide-mediated polymerization

    NARCIS (Netherlands)

    Habraken, G.J.M.; Peeters, M.; Thornton, P.D.; Koning, C.E.; Heise, A.

    2011-01-01

    Combining controlled radical polymerizations and a controlled polypeptide synthetic technique, such as N-carboxyanhydride (NCA) ring-opening polymerization, enables the generation of well-defined block copolymers to be easily accessible. Here we combine NCA polymerization with the nitroxide-mediated

  3. Attractive and repulsive magnetic suspension systems overview

    Science.gov (United States)

    Cope, David B.; Fontana, Richard R.

    1992-01-01

    Magnetic suspension systems can be used in a wide variety of applications. The decision of whether to use an attractive or repulsive suspension system for a particular application is a fundamental one which must be made during the design process. As an aid to the designer, we compare and contrast attractive and repulsive magnetic suspension systems and indicate whether and under what conditions one or the other system is preferred.

  4. Introducing Dual Suspension System in Road Vehicles

    OpenAIRE

    Imtiaz Hussain; Jawaid Daudpoto; Ali Asghar Memon

    2013-01-01

    The main objective of suspension system is to reduce the motions of the vehicle body with respect to road disturbances. The conventional suspension systems in road vehicles use passive elements such as springs and dampers to suppress the vibrations induced by the irregularities in the road. But these conventional suspension systems can suppress vibrations to a certain limit. This paper presents a novel idea to improve the ride quality of roads vehicles without compromising vehicle?s stability...

  5. Time Varying Behavior of the Loudspeaker Suspension

    DEFF Research Database (Denmark)

    Pedersen, Bo Rohde; Agerkvist, Finn T.

    2007-01-01

    The suspension part of the electrodynamic loudspeaker is often modelled as a simple linear spring with viscous damping, however the dynamic behaviour of the suspension is much more complicated than predicted by such a simple model. At higher levels the compliance becomes non-linear and often chan...... changes during excitation at high levels. This paper investigates how the compliance of the suspension depends on the excitation, i.e. level and frequency content. The measurements are compared with other known measurement methods of the suspension....

  6. Introducing Dual Suspension System in Road Vehicles

    Directory of Open Access Journals (Sweden)

    Imtiaz Hussain

    2013-04-01

    Full Text Available The main objective of suspension system is to reduce the motions of the vehicle body with respect to road disturbances. The conventional suspension systems in road vehicles use passive elements such as springs and dampers to suppress the vibrations induced by the irregularities in the road. But these conventional suspension systems can suppress vibrations to a certain limit. This paper presents a novel idea to improve the ride quality of roads vehicles without compromising vehicle?s stability. The paper proposes the use of primary and secondary suspension to suppress the vibrations more effectively.

  7. Applications of positron annihilation spectroscopy to polymeric and biological systems

    International Nuclear Information System (INIS)

    Jean, Y.C.; Chen, Hongmin; Liu, Guang; Chakka, Lakshmi; Gadzia, Joseph E.

    2007-01-01

    Positron annihilation spectroscopy (PAS) is a novel radio-analytical technique which uses the positron (anti-electron) and is capable of probing the atomic and molecular scale (0.2-2 nm) free-volume and hole properties in polymeric and biological materials. Recently, we developed positron annihilation lifetime and Doppler broadening of energy spectroscopies coupled with a variable mono-energetic positron beam to measure the free-volume depth profile from the surface, interfaces, and to the bulk. This paper presents applications of PAS to determine multi-layer structures, glass transition temperatures in nano-scale polymeric films and to detect cancer in the human skin. (author)

  8. An Asymmetric Runaway Domain Swap Antithrombin Dimer as a Key Intermediate for Polymerization Revealed by Hydrogen/Deuterium-Exchange Mass Spectrometry

    DEFF Research Database (Denmark)

    Trelle, Morten Beck; Pedersen, Shona H; Østerlund, Eva Christina

    2017-01-01

    Antithrombin deficiency is associated with increased risk of venous thrombosis. In certain families, this condition is caused by pathogenic polymerization of mutated antithrombin in the blood. To facilitate future development of pharmaceuticals against antithrombin polymerization, an improved und...... strongly supports a β4A-β5A β-hairpin runaway domain swap mechanism for antithrombin polymerization. HDX-MS thus holds exceptional promise as an enabling analytical technique in the efforts toward future pharmacological intervention with protein polymerization and associated diseases....

  9. A study of the initiator concentration’s effect on styrene-divinylbenzene polymerization with iron particles

    Directory of Open Access Journals (Sweden)

    Bárbara M. da Conceição

    2011-01-01

    Full Text Available This paper describes the preparation of magnetic copolymer obtained from suspension polymerization of styrene (Sty and divinylbenzene (DVB in the presence of iron particles treated and not treated with oleic acid. The magnetic copolymers were characterized according to their morphology, particle size distribution and magnetic properties. The results show that incorporation of iron particles significantly changed the particles’ morphology. All samples presented higher saturation magnetization than the values reported in the literature and the particle size distribution was more monodisperse when the polymerization was conducted with 5%wt of benzoyl peroxide (BPO.

  10. Comparison of the compressive yield response of aggregated suspensions: Pressure filtration, centrifugation, and osmotic consolidation

    International Nuclear Information System (INIS)

    Miller, K.T.; Melant, R.M.; Zukoski, C.F.

    1996-01-01

    The compressive rheological responses of suspensions containing flocculated kaolin, alumina (average particle sizes of 0.2 and 0.5 microm), and hydrous zirconia (average particle sizes of 8, 57, and 139 nm) particles have been measured using three different techniques: pressure filtration, volume fraction profile during centrifugation, and sediment height during centrifugation at multiple spinning speeds. While the volume fraction profile technique appears to be experimentally most robust, equivalent responses are found using the different techniques, indicating that the compressive yield stress is a material property of a given suspension. The compressive yield stress of each suspension increases rapidly with volume fraction but cannot be generally described using simple power-law or exponential fits. The compressive yield stress also increases with the inverse square of particle size. The packing behavior of the suspensions undergoing osmotic consolidation is compared with the mechanical compressive yield response. Some suspensions exhibited the same packing behavior as in the mechanical techniques, while others consistently packed to higher densities during osmotic consolidation. Although equivalent osmotic and mechanical loads do not always result in the same volume fractions, the similar increases in volume fraction with applied driving force suggest that both the osmotic and mechanical techniques are controlled by the force needed to rearrange the particle network

  11. An isotropic suspension system for a biaxial accelerometer using electroplated thick metal with a HAR SU-8 mold

    International Nuclear Information System (INIS)

    Lee, Jin Seung; Lee, Seung S

    2008-01-01

    In this paper, a novel approach is developed to design an isotropic suspension system using thick metal freestanding micro-structures combining bulk micro-machining with electroplating based on a HAR SU-8 mold. An omega-shape isotropic suspension system composed of circular curved beams that have free switching of imaginary boundary conditions is proposed. This novel isotropic suspension design is not affected by geometric dimensional parameters and always achieves matching stiffness along the principle axes of elasticity. Using the finite element method, the isotropic suspension system was compared with an S-shaped meandering suspension system. In order to realize the suggested isotropic suspension system, a cost-effective fabrication process using electroplating with the SU-8 mold was developed to avoid expensive equipment and materials such as deep reactive-ion etching (DRIE) or a silicon-on-insulator (SOI) wafer. The fabricated isotropic suspension system was verified by electromagnetic actuation experiments. Finally, a biaxial accelerometer with isotropic suspension system was realized and tested using a vibration generator system. The proposed isotropic suspension system and the modified surface micro-machining technique based on electroplating with an SU-8 mold can contribute towards minimizing the system size, simplifying the system configuration, reducing the system price of and facilitating mass production of various types of low-cost sensors and actuators

  12. Recent advances on polymeric membranes for membrane reactors

    KAUST Repository

    Buonomenna, M. G.

    2012-06-24

    Membrane reactors are generally applied in high temperature reactions (>400 °C). In the field of fine chemical synthesis, however, much milder conditions are generally applicable and polymeric membranes were applied without their damage. The successful use of membranes in membrane reactors is primary the result of two developments concerning: (i) membrane materials and (ii) membrane structures. The selection of a suited material and preparation technique depends on the application the membrane is to be used in. In this chapter a review of up to date literature about polymers and configuration catalyst/ membranes used in some recent polymeric membrane reactors is given. The new emerging concept of polymeric microcapsules as catalytic microreactors has been proposed. © 2012 Bentham Science Publishers. All rights reserved.

  13. Gamma radiation-polymerized methacrylates used as heavy metals adsorbents

    International Nuclear Information System (INIS)

    Barrera D, C.; Roa M, G.; Balderas H, P.; Bilyeu, B.; Urena N, F.

    2009-01-01

    Heavy metal removal from aqueous solution is a priority research area since the actual methods are costly and a major drawback is the large amounts of sludge generated when applying traditional techniques. Adsorption is a physiochemical wastewater treatment process, which is gaining prominence as a means of producing high quality effluents, which are low in metal ion concentrations. The development of inexpensive adsorbents for the treatment of wastewater is an important area in environmental sciences. In this work we describe some of the physical and chemical phenomena that take place in the polymerization of methacrylates when gamma radiation is used. We explain how polymeric material characterization equipment are used for obtaining information regarding the material properties. Then we explain how the new polymeric material obtained can be use for the wastewater treatment. Finally, a comparison in the heavy metal removal from aqueous solution with other sorbent materials is presented. (Author)

  14. Applications of polymeric micelles with tumor targeted in chemotherapy

    International Nuclear Information System (INIS)

    Ding Hui; Wang Xiaojun; Zhang Song; Liu Xinli

    2012-01-01

    Polymeric micelles (PMs) have gained more progress as a carrier system with the quick development of biological and nanoparticle techniques. In particular, PMs with smart targeting can deliver anti-cancer drugs directly into tumor cells at a sustained rate. PMs with core–shell structure (with diameters of 10 ∼ 100 nm) have been prepared by a variety of biodegradable and biocompatible polymers via a self-assembly process. The preparation of polymeric micelles with stimuli-responsive block copolymers or modification of target molecules on polymeric micelles’ surface are able to significantly improve the efficiency of drug delivery. Polymeric micelles, which have been considered as a novel promising drug carrier for cancer therapeutics, are rapidly evolving and being introduced in an attempt to overcome several limitations of traditional chemotherapeutics, including water solubility, tumor-specific accumulation, anti-tumor efficacy, and non-specific toxicity. This review describes the preparation of polymeric micelles and the targeted modification which greatly enhance the effects of chemotherapeutic agents.

  15. Characterization of polymeric microneedle arrays for transdermal drug delivery.

    Directory of Open Access Journals (Sweden)

    Yusuf K Demir

    Full Text Available Microfabrication of dissolvable, swellable, and biodegradable polymeric microneedle arrays (MNs were extensively investigated based in a nano sensitive fabrication style known as micromilling that is then combined with conventional micromolding technique. The aim of this study was to describe the polymer selection, and optimize formulation compounding parameters for various polymeric MNs. Inverse replication of micromilled master MNs reproduced with polydimethylsiloxane (PDMS, where solid out of plane polymeric MNs were subsequently assembled, and physicochemically characterized. Dissolvable, swellable, and biodegradable MNs were constructed to depth of less than 1 mm with an aspect ratio of 3.6, and 1/2 mm of both inter needle tip and base spacing. Micromolding step also enabled to replicate the MNs very precisely and accurate. Polymeric microneedles (MN precision was ranging from ± 0.18 to ± 1.82% for microneedle height, ± 0.45 to ± 1.42% for base diameter, and ± 0.22 to ± 0.95% for interbase spacing. Although dissolvable sodium alginate MN showed less physical robustness than biodegradable polylactic-co-glycolic acid MN, their thermogravimetric analysis is of promise for constructing these polymeric types of matrix devices.

  16. Radiation initiated polymerization of trioxane and stabilization of polyoxymethylene

    International Nuclear Information System (INIS)

    Rao, M.H.; Ramanan, G.; Kunjappu, J.T.; Rao, K.N.

    1990-01-01

    Gamma ray induced polymerization of trioxane from an indigenous source (M/s. Nuchem Plastics, Faridabad) has been investigated by both in-source and post polymerization techniques. Impurity levels in the trioxane samples are determined and compared with those in an imported material. Critical evaluation of the results of its purification by different methods, viz. treatment with molecular sieves, crystallization from solvents and their variations, has been carried out prior to optimising the conditions of polymerization. A novel but simple purification procedure employing benzene as the solvent which is found to form a ternary azeotrope with trioxane and water has been developed. The effect of these purification methods on the polymerization efficiency and their dependence on the molecular weight of the polymer formed are also discussed. Experimental details of polymerizing trioxane in 10 kg scale are also described. To improve upon the thermal stabilty of the polyoxymethylene thus formed, protection of the free hydroxyl end groups (end-capping) has been achieved by an acetylation procedure using acetic anhydride in presence of catalytic amounts of sodium acetate. (author). 11 tabs., 4 figs

  17. Polymeric media for tritium fixation

    International Nuclear Information System (INIS)

    Franz, J.A.; Burger, L.L.

    1975-01-01

    The synthesis and leach testing of several polymeric media for tritium fixation are presented. Tritiated bakelite, poly(acrylonitrile) and polystyrene successfully fixed tritium. Tritium leach rates at the tracer level appear to be negligible. Advantages and disadvantages of the processes are discussed, and further bench-scale investigations underway are reported. Rough cost estimates are presented for the different media and are compared with alternate approaches such as deep-well injection and long-term tank storage. Polymeric media costs are high compared to deep-well storage and are of the same order of magnitude per liter of water as for isotopic enrichment. With this limitation, polymeric media can be economically feasible only for highly concentrated tritiated wastes. It is recommended that the bakelite and polystyrene processes be examined on a larger scale to permit more accurate cost analysis and process design. (auth)

  18. Olefin metathesis and metathesis polymerization

    CERN Document Server

    Ivin, K J

    1997-01-01

    This book is a follow-up to Ivins Olefin Metathesis, (Academic Press, 1983). Bringing the standard text in the field up to date, this Second Edition is a result of rapid growth in the field, sparked by the discovery of numerous well-defined metal carbene complexes that can act as very efficient initiators of all types of olefin metathesis reaction, including ring-closing metathesis of acyclic dienes, enynes, and dienynes; ring-opening metathesis polymerizationof cycloalkenes, acyclic diene metathesis polymerization; and polymerization of alkynes, as well as simple olefin metathesis. Olefin Metathesis and Metathesis Polymerization provides a broad, up-to-date account of the subject from its beginnings in 1957 to the latest applications in organic synthesis. The book follows the same format as the original, making it useful toteachers and to researchers, and will be of particular interest to those working in the fields of organic chemistry, polymer chemistry, organometallic chemistry, catalysis, materials scien...

  19. 36 CFR 296.10 - Suspension and revocation of permits.

    Science.gov (United States)

    2010-07-01

    ... AGRICULTURE PROTECTION OF ARCHAEOLOGICAL RESOURCES: UNIFORM REGULATIONS § 296.10 Suspension and revocation of... correct the situation which led to suspension of the permit. (b) Suspension or revocation for management...

  20. Design analysis of formula student race car suspension system

    Science.gov (United States)

    Wirawan, Julian Wisnu; Ubaidillah, Aditra, Rama; Alnursyah, Rafli; Rahman, Rizki Abdul; Cahyono, Sukmaji Indro

    2018-02-01

    Design analysis of suspension especially for racecar suspension is very crucial to achieve maximum performance and handling. Suspension design may vary depending on the road terrain and the vehicle purpose itself, such as high speed or off-road vehicle. This paper focused on the suspension which used for racecar vehicle. The suspension type used was unequal double wishbone. This model is used because of its stability for high-speed usage compared to another kind of suspension. The suspension parameter was calculated to achieve desired performance. The result is the motion ratio of the designed suspension geometry. The obtained value of motion ratio was 1:2 for front suspension and 1:1 for the rear suspension. These calculation result the front suspension is still too soft, which the optimal motion ratio should be kept around 1:1 for better handling. This problem caused by the lack of space for suspension linkage.

  1. 39 CFR 320.9 - Revocation or amendment of suspensions.

    Science.gov (United States)

    2010-07-01

    ... SUSPENSION OF THE PRIVATE EXPRESS STATUTES § 320.9 Revocation or amendment of suspensions. These suspensions... of operations (in dollar or volume terms, whichever is larger) lower than that antedating the...

  2. Effective flocculation of fine mineral suspensions using Moringa oleifera seeds

    Energy Technology Data Exchange (ETDEWEB)

    Pickett, T.M. [Bureau of Mines, Reno, NV (United States)

    1995-12-31

    The purpose of this research was to investigate the feasibility of using Moringa oleifera seeds, or the active components of the seeds, in the clarification of waters containing suspended mineral fines. In comparative testing using a hematite suspension, the flocculating activity of Moringa oleifera seeds was better than alum. Twenty milligrams of seed powder was sufficient to clarify the hematite to near zero turbidity, while the same amount of alum had a minimal effect on turbidity. Extracts were prepared from the seeds in an attempt to separate the proteins. A crude protein extract was enriched by lowering the pH to 6.0. Only 0.08 mg/L of the enriched extract was required to flocculate a minusil suspension. Environmentally friendly protein flocculants could theoretically be produced and enhanced with recombinant DNA techniques as an alternative to chemical flocculants currently used in water treatment.

  3. Optical detection of magnetic nanoparticles in colloidal suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Gimenez, Alejandro J.; Ramirez-Wong, Diana G.; Favela-Camacho, Sarai E. [Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional Unidad Querétaro, Querétaro, México (Mexico); Sanchez, Isaac C. [Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712 (United States); Yáñez-Limón, J.M.; Luna-Bárcenas, Gabriel [Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional Unidad Querétaro, Querétaro, México (Mexico)

    2016-03-15

    This study reports the change of light transmittance and light scattering dispersion by colloidal suspensions of magnetic nanoparticles. Optical changes were observed during the application of transversal magnetic fields to magnetic nanoparticles and nanowires at concentrations spanning from 20 µg/mL to 2 ng/mL. Results show that light scattering modulation is a simple, fast and inexpensive method for detection of magnetic nanoparticles at low concentrations. Frequency and time response of the optical modulation strongly depends on the geometry of the particles. In this regard, light transmittance and scattering measurements may prove useful in characterizing the morphology of suspended nanoparticles. - Highlights: • A simple route to characterize magnetic nanowire suspension is proposed. • Studied concentration as low as 2 ng/mL compares with more complex techniques. • Transmission and scattering modes allow full characterization of nanoparticles.

  4. Linear viscoelastic properties of aging suspensions

    NARCIS (Netherlands)

    Purnomo, E.H.; Purnomo, E.H; van den Ende, Henricus T.M.; Mellema, J.; Mugele, Friedrich Gunther

    2006-01-01

    We have examined the linear viscoelastic behavior of poly-N-isopropylacrylamide (PNIPAM) microgel suspensions in order to obtain insight in the aging processes in these densely packed suspensions at various temperatures below the volume transition temperature. The system is found to display a strong

  5. 49 CFR 393.207 - Suspension systems.

    Science.gov (United States)

    2010-10-01

    ... braking system. The vehicle shall be level (not tilting to the left or right). Air leakage shall not be... 49 Transportation 5 2010-10-01 2010-10-01 false Suspension systems. 393.207 Section 393.207... NECESSARY FOR SAFE OPERATION Frames, Cab and Body Components, Wheels, Steering, and Suspension Systems § 393...

  6. 41 CFR 105-74.670 - Suspension.

    Science.gov (United States)

    2010-07-01

    ... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Suspension. 105-74.670 Section 105-74.670 Public Contracts and Property Management Federal Property Management Regulations System...-GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Definitions § 105-74.670 Suspension...

  7. 36 CFR 25.3 - Supervision; suspensions.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Supervision; suspensions. 25.3 Section 25.3 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR NATIONAL MILITARY PARKS; LICENSED GUIDE SERVICE REGULATIONS § 25.3 Supervision; suspensions. (a) The guide service will operate under the direction...

  8. Resveratrol immobilization and release in polymeric hydrogels

    International Nuclear Information System (INIS)

    Momesso, Roberta Grazzielli Ramos Alves Passarelli

    2010-01-01

    Resveratrol (3, 4', 5-trihydroxystilbene) is a polyphenolic produced by a wide variety of plants in response to injury and found predominantly in grape skins. This active ingredient has been shown to possess benefits for the health, such as the antioxidant capacity which is related to the prevention of several types of cancer and skin aging. However, the oral bioavailability of resveratrol is poor and makes its topical application interesting. The purpose of this study was to immobilize resveratrol in polymeric hydrogels to obtain a release device for topical use. The polymeric matrices composed of poli(N-vinyl-2-pyrrolidone) (PVP), poly(ethyleneglycol) (PEG) and agar or PVP and glycerol irradiated at 20 kGy dose were physical-chemically characterized by gel fraction and swelling tests and its preliminary biocompatibility by in vitro test of cytotoxicity using the technique of neutral red uptake. Due to low solubility of resveratrol in water, the addition of 2% ethanol to the matrices was verified. All matrices showed a high crosslinking degree, capacity of swelling and the preliminary cytotoxicity test showed nontoxicity effect. The devices were obtained by resveratrol immobilization in polymeric matrices, carried out in a one-or-two-steps process, that is, before or after irradiation, respectively. The one step resveratrol devices were characterized by gel fraction, swelling tests and preliminary biocompatibility, and their properties were maintained even after the resveratrol incorporation. The devices containing 0,05% of resveratrol obtained by one-step process and 0,1% of resveratrol obtained by two-steps process were submitted to the release test during 24 h. Resveratrol quantification was done by high performance liquid chromatography (HPLC). The results obtained in the kinetics of release showed that only the devices obtained by two-step process release the resveratrol, which demonstrate antioxidant capacity after the release. (author)

  9. The molecular aggregation of pyronin Y in natural bentonite clay suspension

    International Nuclear Information System (INIS)

    Meral, Kadem; Yilmaz, Nuray; Kaya, Mehmet; Tabak, Ahmet; Onganer, Yavuz

    2011-01-01

    The molecular aggregation and spectroscopic properties of Pyronin Y (PyY) in the suspension containing natural bentonite clay were studied using molecular absorption, steady-state and time-resolved fluorescence spectroscopy techniques. Interaction between the clay particles and the cationic dye compounds in aqueous solution resulted in significant changes in spectral properties of PyY compared to its molecular behavior in deionized water at the same concentration. These changes were due to the formation of dimer and aggregate of PyY in the clay suspension as well as the presence of the dye monomer. The H-type aggregates of PyY in the clay suspension were identified by the observation of a blue-shifted absorption band of the dye compared to that of its monomer. In spite of diluted dye concentrations, the H-aggregate of PyY in the clay suspension was formed. The intensive aggregation in the clay suspension attributed to the localized high dye concentration on the negatively charged clay surfaces. Adsorption sites of PyY on the clay particles were discussed by deconvulated absorption and excitation spectra. Fluorescence spectroscopy studies revealed that the fluorescence intensity of PyY in the clay suspension is decreased by H-aggregates drastically. Moreover, the presence of H-aggregates in the clay suspension resulted in the decrease of fluorescence lifetime and quantum yield of PyY compared to those in deionized water. - Highlights: → Molecular behavior of PyY adsorbed on clay surface was followed spectroscopically. → H-aggregates of PyY in the clay suspension were formed at very low dye concentrations. → The intensive H-aggregate structure drastically reduced the fluorescence intensity of PyY. → The fluorescence lifetime and quantum yield of PyY in the clay suspension was discussed.

  10. Time response analysis in suspension system design of a high-speed car

    Science.gov (United States)

    Pagwiwoko, Cosmas Pandit

    2010-03-01

    A land speed record vehicle is designed to run on a flat surface like salt lake where the wheels are normally made from solid metal with a special suspension system. The suspension is designed to provide a stable platform to keep the wheel treads on tract, to insulate the car and the driver from the surface irregularities and to take part of good handling properties. The surface condition of the lake beds is basically flat without undulations but with inconsistent surface textures and ridges. Spring with nonlinear rate is used with the reason that the resistance builds up roughly proportional to the aerodynamic download for keeping the height more nearly constant. The objective of the work is to produce an efficient method for assisting the design of suspension system. At the initial step, the stiffness and the damping constants are determined based on RMS optimization by following the optimization strategy i.e. to minimize the absolute acceleration respect to the relative displacement of the suspension. Power bond graph technique is then used to model the nonlinearity of the components i.e. spring and dashpot of the suspension system. This technique also enables to incorporate the interactions of dynamic response of the vehicle's body with aerodynamic flow as a result of the base excitation of the ground to the wheels. The simulation is conducted on the platform of Simulink-MATLAB and the interactions amongst the components within the system are observed in time domain to evaluate the effectiveness of the suspension.

  11. Functional Based Adaptive and Fuzzy Sliding Controller for Non-Autonomous Active Suspension System

    Science.gov (United States)

    Huang, Shiuh-Jer; Chen, Hung-Yi

    In this paper, an adaptive sliding controller is developed for controlling a vehicle active suspension system. The functional approximation technique is employed to substitute the unknown non-autonomous functions of the suspension system and release the model-based requirement of sliding mode control algorithm. In order to improve the control performance and reduce the implementation problem, a fuzzy strategy with online learning ability is added to compensate the functional approximation error. The update laws of the functional approximation coefficients and the fuzzy tuning parameters are derived from the Lyapunov theorem to guarantee the system stability. The proposed controller is implemented on a quarter-car hydraulic actuating active suspension system test-rig. The experimental results show that the proposed controller suppresses the oscillation amplitude of the suspension system effectively.

  12. On-demand photoinitiated polymerization

    Science.gov (United States)

    Boydston, Andrew J; Grubbs, Robert H; Daeffler, Chris; Momcilovic, Nebojsa

    2013-12-10

    Compositions and methods for adjustable lenses are provided. In some embodiments, the lenses contain a lens matrix material, a masking compound, and a prepolymer. The lens matrix material provides structure to the lens. The masking compound is capable of blocking polymerization or crosslinking of the prepolymer, until photoisomerization of the compound is triggered, and the compound is converted from a first isomer to a second isomer having a different absorption profile. The prepolymer is a composition that can undergo a polymerization or crosslinking reaction upon photoinitiation to alter one or more of the properties of the lenses.

  13. Pentafluorosulfanyl Substituents in Polymerization Catalysis.

    Science.gov (United States)

    Kenyon, Philip; Mecking, Stefan

    2017-10-04

    Highly electron-withdrawing pentafluorosulfanyl groups were probed as substituents in an organometallic catalyst. In Ni(II) salicylaldiminato complexes as an example case, these highly electron-withdrawing substituents allow for polymerization of ethylene to higher molecular weights with reduced branching due to significant reductions in β-hydrogen elimination. Combined with the excellent functional group tolerance of neutral Ni(II) complexes, this suppression of β-hydrogen elimination allows for the direct polymerization of ethylene in water to nanocrystal dispersions of disentangled, ultrahigh-molecular-weight linear polyethylene.

  14. Osmotic consolidation of suspensions and gels

    International Nuclear Information System (INIS)

    Miller, K.T.; Zukoski, C.F.

    1994-01-01

    An osmotic method for the consolidation of suspensions of ceramic particles is demonstrated. Concentrated solutions of poly(ethylene oxide) are separated from a suspension of ceramic particles by a semipermeable membrane, creating a gradient in solvent chemical potential. Solvent passes from the suspension into the polymer solution, lowering its free energy and consolidating the suspension. Dispersions of stable 8-nm hydrous zirconia particles were consolidated to over 47% by volume. Suspensions of α-alumina in three states of aggregation (dispersed, weakly flocculated, and strongly flocculated) were consolidated to densities greater than or equal to those produced in conventional pressure filtration. Moreover, the as-consolidated alumina bodies were partially drained of fluid during the osmotic consolidation process, producing cohesive partially dried bodies with improved handling characteristics

  15. Clogging in constricted suspension flows

    Science.gov (United States)

    Marin, Alvaro; Lhuissier, Henri; Rossi, Massimiliano; Kähler, Christian J.

    2018-02-01

    The flow of a charged-stabilized suspension through a single constricted channel is studied experimentally by tracking the particles individually. Surprisingly, the behavior is found to be qualitatively similar to that of inertial dry granular systems: For small values of the neck-to-particle size ratio (D /d reported for granular systems and agree for moderate particle volume fraction (ϕ ≈20 % ) with a simple stochastic model for the number of particles at the neck. For larger neck sizes (D /d >3 ), even at the largest ϕ (≈60 %) achievable in the experiments, an uninterrupted particle flow is observed, which resembles that of an hourglass. This particularly small value of D /d (≃3 ) at the transition to a practically uninterrupted flow is attributed to the low effective friction between the particles, achieved by the particle's functionalization and lubrication.

  16. Next Generation Suspension Dynamics Algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Schunk, Peter Randall [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Higdon, Jonathon [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Chen, Steven [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-12-01

    This research project has the objective to extend the range of application, improve the efficiency and conduct simulations with the Fast Lubrication Dynamics (FLD) algorithm for concentrated particle suspensions in a Newtonian fluid solvent. The research involves a combination of mathematical development, new computational algorithms, and application to processing flows of relevance in materials processing. The mathematical developments clarify the underlying theory, facilitate verification against classic monographs in the field and provide the framework for a novel parallel implementation optimized for an OpenMP shared memory environment. The project considered application to consolidation flows of major interest in high throughput materials processing and identified hitherto unforeseen challenges in the use of FLD in these applications. Extensions to the algorithm have been developed to improve its accuracy in these applications.

  17. Graphite suspension in carbon dioxide

    International Nuclear Information System (INIS)

    Roche, R.

    1965-01-01

    Since 1963 the Atomic Division of SNECMA has been conducting, under a contract with the CEA, an experimental work with a two-component fluid comprised of carbon dioxide and small graphite particles. The primary purpose was the determination of basic engineering information pertaining to the stability and the flowability of the suspension. The final form of the experimental loop consists mainly of the following items: a light-phase compressor, a heavy-phase pump, an electrical-resistance type heater section, a cooling heat exchanger, a hairpin loop, a transparent test section and a separator. During the course of the testing, it was observed that the fluid could be circulated quite easily in a broad range of variation of the suspension density and velocity - density from 30 to 170 kg/m 3 and velocity from 2 to 24 m/s. The system could be restarted and circulation maintained without any difficulty, even with the heavy-phase pump alone. The graphite did not have a tendency to pack or agglomerate during operation. No graphite deposition was observed on the wall of the tubing. A long period run (250 hours) has shown the evolution of the particle dimensions. Starting with graphite of surface area around 20 m 2 /g (graphite particles about 1 μ), the powder surface area reaches an asymptotic value of 300 m 2 /g (all the particles less than 0.3 μ). Moisture effect on flow stability, flow distribution between two parallel channels, pressure drop in straight tubes, recompression ratio in diffusers were also investigated. (author) [fr

  18. Novel distributed strain sensing in polymeric materials

    International Nuclear Information System (INIS)

    Abot, Jandro L; Song, Yi; Medikonda, Sandeep; Rooy, Nathan; Schulz, Mark J

    2010-01-01

    Monitoring the state of strain throughout an entire structure is essential to determine its state of stress, detect potential residual stresses after fabrication, and also to help to establish its integrity. Several sensing technologies are presently available to determine the strain in the surface or inside a structure. Large sensor dimensions, complex signal conditioning equipment, and difficulty in achieving a widely distributed system have however hindered their development into robust structural health monitoring techniques. Recently, carbon nanotube forests were spun into a microscale thread that is electrically conductive, tough, and easily tailorable. The thread was integrated into polymeric materials and used for the first time as a piezoresistive sensor to monitor strain and also to detect damage in the material. It is revealed that the created self-sensing polymeric materials are sensitive to normal strains above 0.07% and that the sensor thread exhibits a perfectly linear delta resistance–strain response above 0.3%. The longitudinal gauge factors were determined to be in the 2–5 range. This low cost and simple built-in sensor thread may provide a new integrated and distributed sensor technology that enables robust real-time health monitoring of structures

  19. Naratriptan hydrochloride in extemporaneosly compounded oral suspensions.

    Science.gov (United States)

    Zhang, Y P; Trissel, L A; Fox, J L

    2000-01-01

    The purpose of this study was to determine the pharmaceutical acceptability and chemical stability of naratriptan hydrochloride in three extemporaneously compounded suspension formulations. The naratriptan-hydrochloride oral suspensions were prepared from 2.5-mg commercial tablets yielding a nominal naratriptan concentration of 0.5 mg/mL. The suspension vehicles selected for testing were Syrpalta, an equal-parts mixture of Ora-Plus and Ora-Sweet, and an equal-parts mixture of Ora-Plus and Ora-Sweet SF. The tablets were crushed and thoroughly triturated to a fine powder using a porcelain mortar and pestle. The powder was incorporated into a portion of the Syrpalta or Ora-Plus suspension vehicle and mixed until homogeneous. The mixtures were then brought to volume with Syrpalta, Ora-Sweet or Ora-Sweet SF, as appropriate. The suspensions were packaged in amber, plastic, screw-cap prescription bottles and stored at 23 deg C for seven days and 4 deg C for 90 days. An adequate suspension was never achieved in Syrpalta. The crushed-tablet powder did not produce a uniformly dispersed mixture and exhibited clumping and a high rate of sedimentation. A distinct layer of the solid tablet material settled immediately after shaking. Over the next four hours, a densely packed, yellow, caked layer formed at the bottom of the containers, making resuspension difficult. During storage, the caking became worse. Chemical analysis was not performed. The Ora-Plus and Ora-Sweet or Ora-Sweet SF suspensions had a slight greenish cast and were resuspended without difficulty by shaking for approximately ten seconds, yielding easily poured and homogeneous mixtures throughout the study. Visible settling and layering did not begin for four hours with the Ora-Sweet suspension and 24 hours for the Ora-Sweet SF suspension. High pressure liquid chromatographic analysis found that the naratriptan concentration in both suspension-vehicle combinations exhibited little or no loss for seven days at 23

  20. Novel polymeric materials from triglycerides

    Science.gov (United States)

    Triglycerides are good platforms for new polymeric products that can substitute for petroleum-based materials. As part of our research emphasis in sustainability and green polymer chemistry, we have explored a number of reactions in efforts to produce a wide range of value-added products. In this ...

  1. Novel solid state polymeric batteries

    Energy Technology Data Exchange (ETDEWEB)

    Patrick, A.; Glasse, M.; Latham, R.; Linford, R.

    1986-01-01

    AC conductivity measurements have been performed on a number of polymeric electrolytes containing Mg, Ca, Sr and Zn perchlorates and Mg and Ca thiocyanates. The electrolytes were characterized using DSC. Results are reported of preliminary tests of cells incorporating anodes of the above metals. 11 refs.

  2. Reactive surfactants in heterophase polymerization

    NARCIS (Netherlands)

    Guyot, A.; Tauer, K.; Asua, J.M.; Es, van J.J.G.S.; Gauthier, C.; Hellgren, A.C.; Sherrington, D.C.; Montoya-Goni, A.; Sjöberg, M.; Sindt, O.; Vidal, F.F.M.; Unzue, M.; Schoonbrood, H.A.S.; Schipper, E.T.W.M.; Lacroix-Desmazes, P.

    1999-01-01

    This paper summarizes the work carried out during 3 years in a Network of the program "Human Capital and Mobility" of the European Union CHRX 93-0159 entitled "Reactive surfactants in heterophase polymerization for high performance polymers". A series of about 25 original papers will be published in

  3. Biodegradable polymeric prodrugs of naltrexone

    NARCIS (Netherlands)

    Bennet, D.B.; Li, X.; Adams, N.W.; Kim, S.W.; Hoes, C.J.T.; Hoes, C.J.T.; Feijen, Jan

    1991-01-01

    The development of a biodegradable polymeric drug delivery system for the narcotic antagonist naltrexone may improve patient compliance in the treatment of opiate addiction. Random copolymers consisting of the ¿-amino acids N5-(3-hydroxypropyl--glutamine and -leucine were synthesized with equimolar

  4. Generating an Engineered Adipose Tissue Flap Using an External Suspension Device.

    Science.gov (United States)

    Wan, Jinlin; Dong, Ziqing; Lei, Chen; Lu, Feng

    2016-07-01

    The tissue-engineering chamber technique can generate large volumes of adipose tissue, which provides a potential solution for the complex reconstruction of large soft-tissue defects. However, major drawbacks of this technique are the foreign-body reaction and the volume limitation imposed by the chamber. In this study, the authors developed a novel tissue-engineering method using a specially designed external suspension device that generates an optimized volume of adipose flap and avoids the implantation of foreign material. The rabbits were processed using two different tissue-engineering methods, the external suspension device technique and the traditional tissue-engineering chamber technique. The adipose flaps generated by the external suspension device had a normal adipose tissue structure that was as good as that generated by the traditional tissue-engineering chamber, but the flap volume was much larger. The final volume of the engineered adipose flap grew between weeks 0 and 36 from 5.1 ml to 30.7 ml in the traditional tissue-engineering chamber group and to 80.5 ml in the external suspension device group. During the generation process, there were no marked differences between the two methods in terms of structural and cellular changes of the flap, except that the flaps in the traditional tissue-engineering chamber group had a thicker capsule at the early stage. In addition, the enlarged flaps generated by the external suspension device could be reshaped into specific shapes by the implant chamber. This minimally invasive external suspension device technique can generate large-volume adipose flaps. Combined with a reshaping method, this technique should facilitate clinical application of adipose tissue engineering.

  5. Self-powered suspension criterion and energy regeneration implementation scheme of motor-driven active suspension

    Science.gov (United States)

    Yan, Shuai; Sun, Weichao

    2017-09-01

    Active suspension systems have advantages on mitigating the effects of vehicle vibration caused by road roughness, which are one of the most important component parts in influencing the performances of vehicles. However, high amount of energy consumption restricts the application of active suspension systems. From the point of energy saving, this paper presents a self-powered criterion of the active suspension system to judge whether a motor-driven suspension can be self-powered or not, and then a motor parameter condition is developed as a reference to design a self-powered suspension. An energy regeneration implementation scheme is subsequently proposed to make the active suspension which has the potential to be self-powered achieve energy-saving target in the real application. In this implementation scheme, operating electric circuits are designed based on different working status of the actuator and power source and it is realizable to accumulate energy from road vibration and supply energy to the actuator by switching corresponding electric circuits. To apply the self-powered suspension criterion and energy regeneration implementation scheme, an active suspension system is designed with a constrained H∞ controller and calculation results indicate that it has the capability to be self-powered. Simulation results show that the performances of the self-powered active suspension are nearly the same as those of the active suspension with an external energy source and can achieve energy regeneration at the same time.

  6. Characterization of cell suspensions from solid tumors

    International Nuclear Information System (INIS)

    Pallavicini, M.

    1985-01-01

    The desirable features of cells in suspension will necessarily be dependent upon the use for which the cells were prepared. Adequate cell yield or recovery is defined by the measurement to be performed. Retention of cellular morphology is important for microscopic identification of cell types in a heterogenous cell suspension, and may be used to determine whether the cells in suspension are representative of those in the tumor in situ. Different dispersal protocols may yield cells with different degrees of clonogenicity, as well as altered biochemical features, such as loss of cellular proteins, surface antigens, nucleotide pools, etc. The quality of the cell suspension can be judged by the degree of cell clumping and level of cellular debris, both of which impact on flow cytometric measurements and studies in which the number of cells be known accurately. Finally, if the data measured on the cells in suspension are to be extrapolated to phenomena occurring in the tumor in situ, it is desirable that the cells in suspension are representative of those in the solid tumor in vivo. This report compares characteristics of tumor cell suspensions obtained by different types of selected disaggregation methods. 33 refs., 2 figs., 4 tabs

  7. Glycine Polymerization on Oxide Minerals

    Science.gov (United States)

    Kitadai, Norio; Oonishi, Hiroyuki; Umemoto, Koichiro; Usui, Tomohiro; Fukushi, Keisuke; Nakashima, Satoru

    2017-06-01

    It has long been suggested that mineral surfaces played an important role in peptide bond formation on the primitive Earth. However, it remains unclear which mineral species was key to the prebiotic processes. This is because great discrepancies exist among the reported catalytic efficiencies of minerals for amino acid polymerizations, owing to mutually different experimental conditions. This study examined polymerization of glycine (Gly) on nine oxide minerals (amorphous silica, quartz, α-alumina and γ-alumina, anatase, rutile, hematite, magnetite, and forsterite) using identical preparation, heating, and analytical procedures. Results showed that a rutile surface is the most effective site for Gly polymerization in terms of both amounts and lengths of Gly polymers synthesized. The catalytic efficiency decreased as rutile > anatase > γ-alumina > forsterite > α- alumina > magnetite > hematite > quartz > amorphous silica. Based on reported molecular-level information for adsorption of Gly on these minerals, polymerization activation was inferred to have arisen from deprotonation of the NH3 + group of adsorbed Gly to the nucleophilic NH2 group, and from withdrawal of electron density from the carboxyl carbon to the surface metal ions. The orientation of adsorbed Gly on minerals is also a factor influencing the Gly reactivity. The examination of Gly-mineral interactions under identical experimental conditions has enabled the direct comparison of various minerals' catalytic efficiencies and has made discussion of polymerization mechanisms and their relative influences possible Further systematic investigations using the approach reported herein (which are expected to be fruitful) combined with future microscopic surface analyses will elucidate the role of minerals in the process of abiotic peptide bond formation.

  8. Glycine Polymerization on Oxide Minerals.

    Science.gov (United States)

    Kitadai, Norio; Oonishi, Hiroyuki; Umemoto, Koichiro; Usui, Tomohiro; Fukushi, Keisuke; Nakashima, Satoru

    2017-06-01

    It has long been suggested that mineral surfaces played an important role in peptide bond formation on the primitive Earth. However, it remains unclear which mineral species was key to the prebiotic processes. This is because great discrepancies exist among the reported catalytic efficiencies of minerals for amino acid polymerizations, owing to mutually different experimental conditions. This study examined polymerization of glycine (Gly) on nine oxide minerals (amorphous silica, quartz, α-alumina and γ-alumina, anatase, rutile, hematite, magnetite, and forsterite) using identical preparation, heating, and analytical procedures. Results showed that a rutile surface is the most effective site for Gly polymerization in terms of both amounts and lengths of Gly polymers synthesized. The catalytic efficiency decreased as rutile > anatase > γ-alumina > forsterite > α- alumina > magnetite > hematite > quartz > amorphous silica. Based on reported molecular-level information for adsorption of Gly on these minerals, polymerization activation was inferred to have arisen from deprotonation of the NH 3 + group of adsorbed Gly to the nucleophilic NH 2 group, and from withdrawal of electron density from the carboxyl carbon to the surface metal ions. The orientation of adsorbed Gly on minerals is also a factor influencing the Gly reactivity. The examination of Gly-mineral interactions under identical experimental conditions has enabled the direct comparison of various minerals' catalytic efficiencies and has made discussion of polymerization mechanisms and their relative influences possible Further systematic investigations using the approach reported herein (which are expected to be fruitful) combined with future microscopic surface analyses will elucidate the role of minerals in the process of abiotic peptide bond formation.

  9. Sedimentation of athermal particles in clay suspensions

    Science.gov (United States)

    Clotet, Xavier; Kudrolli, Arshad

    2015-03-01

    We discuss sedimentation of athermal particles in dense clay suspensions which appear liquid-like to glass-like. These studies are motivated by the physics important to a diverse range of problems including remediation of oil sands after the extraction of hydrocarbons, and formation of filter cakes in bore wells. We approach this problem by first considering collective sedimentation of athermal spherical particles in a viscous liquid in quasi-two dimensional and three dimensional containers. We examine the system using optical and x-ray tomography techniques which gives particle level information besides global information on the evolution of the volume fraction. Unlike sediments in the dilute limit - which can be modeled as isolated particles that sediment with a constant velocity and slow down exponentially as they approach the bottom of the container - we find interaction between the particles through the viscous fluids leads to qualitatively differences. We find significant avalanching behavior and cooperative motion as the grains collectively settle, and non-exponential increase in settling time. We discuss the effect of stirring caused by the sedimenting particles on their viscosity and consequently the sedimentation rates as a function of particle concentration. Supported by Petroleum Research Fund Grant PRF # 54045-ND9.

  10. Static yield stress of a magnetorheological fluid containing Pickering emulsion polymerized Fe2O3/polystyrene composite particles.

    Science.gov (United States)

    Seo, Youngwook P; Kwak, Soonjong; Choi, Hyoung Jin; Seo, Yongsok

    2016-02-01

    The flow behaviors of magnetorheological (MR) suspensions containing Pickering emulsion polymerized Fe2O3/polystyrene (PS) composite particles were reanalyzed using the Seo-Seo model. The experimental shear stress data obtained experimentally from the magnetorheological fluid fit well to the Seo-Seo model, indicating that this model can describe the structural reformation process of the aligned fibers at various shear rates. Unlike the dynamic yield stress obtained from the Cho-Choi-Jhon (CCJ) model, the static yield stresses obtained from the Seo-Seo model exhibit the same quadratic dependence on the magnetic field strength for both pure Fe2O3 particle suspension and Fe2O3/PS particle suspensions, which is in agreement with the predictions of the polarization model. The static yield stress plausibly explains the difference in underlying mechanism of MR fluids. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Magnetic Levitation To Characterize the Kinetics of Free-Radical Polymerization.

    Science.gov (United States)

    Ge, Shencheng; Semenov, Sergey N; Nagarkar, Amit A; Milette, Jonathan; Christodouleas, Dionysios C; Yuan, Li; Whitesides, George M

    2017-12-27

    This work describes the development of magnetic levitation (MagLev) to characterize the kinetics of free-radical polymerization of water-insoluble, low-molecular-weight monomers that show a large change in density upon polymerization. Maglev measures density, and certain classes of monomers show a large change in density when monomers covalently join in polymer chains. MagLev characterized both the thermal polymerization of methacrylate-based monomers and the photopolymerization of methyl methacrylate and made it possible to determine the orders of reaction and the Arrhenius activation energy of polymerization. MagLev also made it possible to monitor polymerization in the presence of solids (aramid fibers, and carbon fibers, and glass fibers). MagLev offers a new analytical technique to materials and polymer scientists that complements other methods (even those based on density, such as dilatometry), and will be useful in investigating polymerizations, evaluating inhibition of polymerizations, and studying polymerization in the presence of included solid materials (e.g., for composite materials).

  12. Simulating Controlled Radical Polymerizations with mcPolymer—A Monte Carlo Approach

    Directory of Open Access Journals (Sweden)

    Georg Drache

    2012-07-01

    Full Text Available Utilizing model calculations may lead to a better understanding of the complex kinetics of the controlled radical polymerization. We developed a universal simulation tool (mcPolymer, which is based on the widely used Monte Carlo simulation technique. This article focuses on the software architecture of the program, including its data management and optimization approaches. We were able to simulate polymer chains as individual objects, allowing us to gain more detailed microstructural information of the polymeric products. For all given examples of controlled radical polymerization (nitroxide mediated radical polymerization (NMRP homo- and copolymerization, atom transfer radical polymerization (ATRP, reversible addition fragmentation chain transfer polymerization (RAFT, we present detailed performance analyses demonstrating the influence of the system size, concentrations of reactants, and the peculiarities of data. Different possibilities were exemplarily illustrated for finding an adequate balance between precision, memory consumption, and computation time of the simulation. Due to its flexible software architecture, the application of mcPolymer is not limited to the controlled radical polymerization, but can be adjusted in a straightforward manner to further polymerization models.

  13. Vehicle lateral dynamics stabilization using active suspension

    Directory of Open Access Journals (Sweden)

    Drobný V.

    2008-12-01

    Full Text Available The paper deals with the investigation of active nonlinear suspension control in order to stabilize the lateral vehicle motion in similar way as systems like ESP do. The lateral stabilization of vehicle based on braking forces can be alternatively provided by the different setting of suspension forces. The basis of this control is the nonlinear property of the tyres. The vehicle has at least four wheels and it gives one or more redundant vertical forces that can be used for the different distribution of vertical suspension forces in such a way that resulting lateral and/or longitudinal forces create the required correction moment for lateral dynamic vehicle stabilization.

  14. Suspension for the low frequency facility

    CERN Document Server

    Cella, G; Di Virgilio, A; Gaddi, A; Viceré, A

    2000-01-01

    We introduce the working principles of the VIRGO Low Frequency Facility (LFF), whose main aim is the measurement of the thermal noise in the VIRGO suspension system. We evaluate the displacement thermal noise of a mirror, which is an intermediate element of a double pendulum suspension system. This double pendulum will be suspended to the last stage of a VIRGO Super-Attenuator (SA), the prototype VIRGO suspension system being tested at the Pisa section of INFN. In the proposed configuration, we evaluate the spectrum of the thermal noise for different choices of the parameters: based on this study, we comment on the future directions to be undertaken in the LFF experiment.

  15. Nanostructured conductive polymeric materials

    Science.gov (United States)

    Al-Saleh, Mohammed H.

    Conductive polymer composites (CPCs) are a suitable alternative to metals in many applications due to their light-weight, corrosion resistance, low cost, ease of processing and design flexibility. CPCs have been formulated using different types of conductive fillers. In this PhD thesis, the focus is on CPCs for electrostatic discharge (ESD) protection and electromagnetic interference (EMI) attenuation. Despite the versatility of conductive fillers, carbon black (CB) has been the dominant filler to make CPCs for ESD protection applications because CB/polymer composites have a cost advantage over all other CPCs. For EMI shielding, stainless steel fibres and metal coated fibers are the preferred fillers, however CPCs made of those fibers are not the dominant EMI shielding materials. Metal coated and polymer plated polymers are the most widely used EMI shielding options. The limited use of CPCs in the EMI shielding market is because the high filler loading required to formulate a composite with an adequate level of shielding remarkably increases the composite price. In order to increase the competitiveness of CPCs, percolation threshold should be minimized as much as possible and composites with high EMI shielding capabilities at low filler loading should be formulated because all conductive fillers are expensive compared to polymers. In this thesis, two different methodologies to reduce percolation threshold in CPCs have been successfully developed and a CPC with exceptional EMI shielding capability has been formulated using copper nanowires as conductive filler. The first percolation threshold reduction technique is based on the selective localization of CB at the interface of immiscible polymer blend. The technique requires adding a copolymer that prefers the blend's interface and for which CB nanoparticles has the highest affinity. The second method is based on producing a CPC powder and then using this powder as a conductive filler to produce composite by dry

  16. Plasma etching of electrospun polymeric nanofibres

    Energy Technology Data Exchange (ETDEWEB)

    Verdonck, Patrick [LSI-PSI-EPUSP, Av. Prof. Luciano Gualberto trav 3, 158, 05508-900 Sao Paulo, SP (Brazil)]. E-mail: verdonck@imec.be; Braga Caliope, Priscila [LSI-PSI-EPUSP, Av. Prof. Luciano Gualberto trav 3, 158, 05508-900 Sao Paulo, SP (Brazil); Moral Hernandez, Emilio del [LSI-PSI-EPUSP, Av. Prof. Luciano Gualberto trav 3, 158, 05508-900 Sao Paulo, SP (Brazil); Silva, Ana Neilde R. da [LSI-PSI-EPUSP, Av. Prof. Luciano Gualberto trav 3, 158, 05508-900 Sao Paulo, SP (Brazil); FATEC-SP, Pca Fernando Prestes, 30 Sao Paulo, SP (Brazil)

    2006-10-25

    Electrospun polymeric nanofibres have several applications because of their high surface area to volume and high length to diameter ratios. This paper investigates the influence of plasma etching on these fibres and the etching mechanisms. For the characterization, SEM analysis was performed to determine the forms and shapes of the fibres and SEM photos were analysed by the technique of mathematical morphology, in order to determine the area on the sample occupied by the fibres and the frequency distribution of the nanofibre diameters. The results showed that the oxygen plasma etches the nanofibres much faster when ion bombardment is present. The form of the fibres is not altered by the etching, indicating the possibility of transport of oxygen atoms over the fibre surface. The most frequent diameter, somewhat surprisingly, is not significantly dependent on the etching process, and remains of the order of 80 nm, indicating that fibres with smaller diameters are etched at high rates.

  17. Investigating high-concentration monoclonal antibody powder suspension in nonaqueous suspension vehicles for subcutaneous injection.

    Science.gov (United States)

    Bowen, Mayumi; Armstrong, Nick; Maa, Yuh-Fun

    2012-12-01

    Developing high-concentration monoclonal antibody (mAb) liquid formulations for subcutaneous (s.c.) administration is challenging because increased viscosity makes injection difficult. To overcome this obstacle, we investigated a nonaqueous powder suspension approach. Three IgG1 mAbs were spray dried and suspended at different concentrations in Miglyol® 840, benzyl benzoate, or ethyl lactate. Suspensions were characterized for viscosity, particle size, and syringeability; physical stability was visually inspected. Suspensions generally outperformed liquid solutions for injectability despite higher viscosity at the same mAb concentrations. Powder formulations and properties had little effect on viscosity or injectability. Ethyl lactate suspensions had lowest viscosity (Miglyol® 840 improved overall performance in high mAb concentration suspensions. This study demonstrated the viability of high mAb concentration (>300 mg/mL) in suspension formulations for s.c. administration. Copyright © 2012 Wiley Periodicals, Inc.

  18. Development of a Fabrication Process Using Suspension Plasma Spray for Titanium Oxide Photovoltaic Device

    Directory of Open Access Journals (Sweden)

    Hsian Sagr Hadi A

    2017-03-01

    Full Text Available In order to reduce the high costs of conventional materials, and to reduce the power necessary for the deposition of titanium dioxide, titanium tetrabutoxide has been developed in the form of a suspension of TiO2 using water instead of expensive ethanol. To avoid sedimentation of hydroxide particles in the suspension, mechanical milling of the suspension was conducted in order to create diffusion in colloidal suspension before using it as feedstock. Consequently, through the creation of a colloidal suspension, coating deposition was able to be conducted without sedimentation of the hydroxide particles in the suspension during the deposition process. Though an amorphous as-deposited coating was able to be deposited, through post heat treatment at 630 °C for 60 min, the chemical structure became anatase rich. In addition, it was confirmed that the post heat treated anatase rich coating had enough photo-catalytic activity to decolor methylene-blue droplets. From these results, this technique was found to have high potential in the low cost photo-catalytic titanium coating production process.

  19. Preparation and encapsulation of white/yellow dual colored suspensions for electrophoretic displays

    Science.gov (United States)

    Han, Jingjing; Li, Xiaoxu; Feng, Yaqing; Zhang, Bao

    2014-11-01

    C.I. Pigment Yellow 181 (PY181) composite particles encapsulated by polyethylene (PE) were prepared by dispersion polymerization method, and C.I. Pigment Yellow 110 (PY110) composite particles encapsulated by polystyrene (PS) with mini-emulsion polymerization method were achieved, respectively. The modified pigments were characterized by fourier transform infrared spectroscopy, scanning electron microscope and transmission electron microscope. Compared with the PE-coated PY 181 pigments, the PS-coated PY-110 particles had a narrow particle size distribution, regular spherical and average particle size of 450 nm. Suspension 1 and suspension 3 were prepared by the two composite particles dispersed in isopar M. A chromatic electrophoretic display cell consisting of yellow particles was successfully fabricated using dispersions of yellow ink particles in a mixed dielectric solvent with white particles as contrast. The response behavior and the contrast ratio to the electric voltage were also examined. The contrast ratio of pigments modified by polystyrene was 1.48, as well as the response time was 2 s, which were better than those of pigments modified by polyethylene.

  20. Synchrotron SAXS/WAXD and rheological studies of clay suspensions in silicone fluid.

    Science.gov (United States)

    Zhang, Li-Ming; Jahns, Christopher; Hsiao, Benjamin S; Chu, Benjamin

    2003-10-15

    Suspensions of two commercial smectite clays, montmorillonite KSF and montmorillonite K10, in a low-viscosity silicone oil (Dow Corning 245 Fluid) were studied by simultaneous synchrotron small-angle X-ray scattering (SAXS)/wide-angle X-ray diffraction (WAXD) techniques and rheological measurements. In the 0.5% (w/v) KSF clay suspension and two K10 clay suspensions (0.5% and 1.0%), WAXD profiles below 2theta=10.0 degrees did not display any characteristic reflection peaks associated with the chosen montmorillonite clays, while corresponding SAXS profiles exhibited distinct scattering maxima, indicating that both clays were delaminated by the silicone oil. In spite of the large increase in viscosity, the clay suspensions exhibited no gel characteristics. Dynamic rheological experiments indicated that the clay/silicone oil suspensions exhibited the behavior of viscoelasticity, which could be influenced by the type and the concentration of the clay. For the K10 clay suspensions, the frequency-dependent loss modulus (G") was greater in magnitude than the storage modulus (G') in the concentration range from 0.5 to 12.0%. The increase in the clay concentration shifted the crossover point between G' and G" into the accessible frequency range, indicating that the system became more elastic. In contrast, the KSF clay suspension exhibited lower G' and G" values, indicating a weaker viscoelastic response. The larger viscoelasticity response in the K10 clay suspension may be due to the acid treatment generating a higher concentration of silanol groups on the clay surface.

  1. A Course in Fluid Mechanics of Suspensions.

    Science.gov (United States)

    Davis, Robert H.

    1989-01-01

    Discusses a course focusing on fluid mechanics and physical chemistry of suspensions. Describes the main themes of the lectures and includes a list of course outlines. Possible textbooks and many journal articles are listed. (YP)

  2. Heat and mass transfer in particulate suspensions

    CERN Document Server

    Michaelides, Efstathios E (Stathis)

    2013-01-01

    Heat and Mass Transfer in Particulate Suspensions is a critical review of the subject of heat and mass transfer related to particulate Suspensions, which include both fluid-particles and fluid-droplet Suspensions. Fundamentals, recent advances and industrial applications are examined. The subject of particulate heat and mass transfer is currently driven by two significant applications: energy transformations –primarily combustion – and heat transfer equipment. The first includes particle and droplet combustion processes in engineering Suspensions as diverse as the Fluidized Bed Reactors (FBR’s) and Internal Combustion Engines (ICE’s). On the heat transfer side, cooling with nanofluids, which include nanoparticles, has attracted a great deal of attention in the last decade both from the fundamental and the applied side and has produced several scientific publications. A monograph that combines the fundamentals of heat transfer with particulates as well as the modern applications of the subject would be...

  3. Experimental Evaluation of Mountain Bike Suspension Systems

    Directory of Open Access Journals (Sweden)

    J. Titlestad

    2003-01-01

    Full Text Available A significant distinction between competitive mountain bikes is whether they have a suspension system. Research studies indicate that a suspension system gives advantages, but it is difficult to quantify the benefits because they depend on so many variables, including the physiology and psychology of the cyclist, the roughness of the track and the design of the suspension system. A laboratory based test rig has been built that allows the number of variables in the system to be reduced and test conditions to be controlled. The test rig simulates regular impacts of the rear wheel with bumps in a rolling road. The physiological variables of oxygen consumption and heart rate were measured, together with speeds and forces at various points in the system. Physiological and mechanical test results both confirm a significant benefit in using a suspension system on the simulated rough track, with oxygen consumption reduced by around 30 % and power transmitted through the pedals reduced by 30 % to 60 %.

  4. Crust formation in drying colloidal suspensions

    KAUST Repository

    Style, R. W.; Peppin, S. S. L.

    2010-01-01

    and the equations of poroelasticity, while the equations of colloid physics govern processes in the suspension. We derive new equations describing this process, including unique boundary conditions coupling the two regions, yielding a moving-boundary model

  5. Increasing Possibilities of Nano suspension

    International Nuclear Information System (INIS)

    Sutradhar, K.B.; Khatun, S.; Luna, I.P.

    2013-01-01

    Nowadays, a very large proportion of new drug candidates emerging from drug discovery programmes are water insoluble and thus poorly bioavailable. To avoid this problem, nano technology for drug delivery has gained much interest as a way to improve the solubility problems. Nano refers to particles size range of 1-1000 nm. The reduction of drug particles into the submicron range leads to a significant increase in the dissolution rate and therefore enhances bioavailability. Nanosuspensions are part of nano technology. This interacts with the body at subcellular (i.e., molecular) scales with a high degree of specificity and can be potentially translated into targeted cellular and tissue-specific clinical applications designed to achieve maximal therapeutic efficacy with minimal side effects. Production of drugs as nanosuspensions can be developed for drug delivery systems as an oral formulation and no noral administration. Here, this review describes the methods of pharmaceutical nano suspension production including advantages and disadvantages, potential benefits, characterization tests, and pharmaceutical applications in drug delivery

  6. Suspension scheme for fuel pin

    International Nuclear Information System (INIS)

    Butts, C.E.; Gray, H.C.

    1975-01-01

    A description is presented of a nuclear fuel pin suspension arrangement comprising, in combination, a rod; a first beam member connected to said rod at one end; a plurality of parallel-spaced slidable fuel support plates attached to said first beam member, the longitudinal axis of first beam member being perpendicular to the longitudinal axis of each of said fuel support plates, a first coupling means disposed along the length of the first beam member for permitting slidable fuel support plates parallel movement with respect to the longitudinal axis of said first beam member, a second coupling means located at one end of each of slidable fuel plates for slidably engaging first coupling means of first beam member, a second beam member connected to the other end of each of parallel-spaced slidable fuel support plates and providing an extension, second beam member being provided with a third coupling means disposed along the length of second beam member at one end thereof; and a plurality of fuel pins provided with a fourth coupling means located at one end of each fuel pin for slidably engaging third coupling means of second beam member to permit each fuel pin parallel movement with respect to the longitudinal axis of second beam member. (U.S.)

  7. Polymeric Micelles as Novel Carriers for Poorly Soluble Drugs--A Review.

    Science.gov (United States)

    Reddy, B Pavan Kumar; Yadav, Hemant K S; Nagesha, Dattatri K; Raizaday, Abhay; Karim, Abdul

    2015-06-01

    Polymeric micelles are used as 'smart drug carriers' for targeting certain areas of the body by making them stimuli-sensitive or by attachment of a specific ligand molecule onto their surface. The main aim of using polymeric micelles is to deliver the poorly water soluble drugs. Now-a-days they are used especially in the areas of cancer therapy also. In this article we have reviewed several aspects of polymeric micelles concerning their mechanism of formation, chemical nature, preparation and characterization techniques, and their applications in the areas of drug delivery.

  8. Immobilization of microbial cells on cellulose-polymer surfaces by radiation polymerization

    International Nuclear Information System (INIS)

    Kumakura, M.; Kaetsu, I.

    1983-01-01

    Streptomyces phaeochromogens cells were immobilized on cellulose-polymer surfaces by radiation polymerization using hydrophilic monomers and paper. The enzyme activity of immobilized cell sheets was higher than that of immobilized cell composites obtained by the usual radiation polymerization technique. The enzyme activity of the sheets was affected by monomer concentration, the thickness of paper, and the degree of polymerization of paper. The copolymerization of hydroxyethyl methacrylate and methoxytetraethyleneglycol methacrylate in the sheets led to a further increase of the enzyme activity due to the increase of the hydrophilicity of the polymer matrix. The Michaelis constant of the sheets from low monomer concentration was close to that of intact cells

  9. Compressed Air Production Using Vehicle Suspension

    OpenAIRE

    Ninad Arun Malpure; Sanket Nandlal Bhansali

    2015-01-01

    Abstract Generally compressed air is produced using different types of air compressors which consumes lot of electric energy and is noisy. In this paper an innovative idea is put forth for production of compressed air using movement of vehicle suspension which normal is wasted. The conversion of the force energy into the compressed air is carried out by the mechanism which consists of the vehicle suspension system hydraulic cylinder Non-return valve air compressor and air receiver. We are co...

  10. SCATTERING FROM RAMIFIED POLYMERIC SYSTEMS

    Directory of Open Access Journals (Sweden)

    M.Benhamou

    2004-01-01

    Full Text Available Here, of great interest to us is a quantitative study of the scattering properties from ramified polymeric systems of arbitrary topology. We consider three types of systems, namely ramified polymers in solution, ramified polymer blends, or ternary mixtures made of two ramified polymers of different chemical nature immersed in a good solvent. To achieve the goal of the study, use is made of the Random Phase Approximation. First we determine the exact expression of the form factor of an ideal ramified polymer of any topology, from which we extract the exact expression of its gyration radius. Using the classical Zimm's formulae and the exact form factor, we determine all scattering properties of these three types of ramified polymeric systems. The main conclusion is that ramification of the chains induces drastic changes of the scattering properties.

  11. MODELING PARTICLE SIZE DISTRIBUTION IN HETEROGENEOUS POLYMERIZATION SYSTEMS USING MULTIMODAL LOGNORMAL FUNCTION

    Directory of Open Access Journals (Sweden)

    J. C. Ferrari

    Full Text Available Abstract This work evaluates the usage of the multimodal lognormal function to describe Particle Size Distributions (PSD of emulsion and suspension polymerization processes, including continuous reactions with particle re-nucleation leading to complex multimodal PSDs. A global optimization algorithm, namely Particle Swarm Optimization (PSO, was used for parameter estimation of the proposed model, minimizing the objective function defined by the mean squared errors. Statistical evaluation of the results indicated that the multimodal lognormal function could describe distinctive features of different types of PSDs with accuracy and consistency.

  12. Flow-induced structure in colloidal suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Vermant, J [Department of Chemical Engineering, K U Leuven, W de Croylaan 46, B-3001 Leuven (Belgium); Solomon, M J [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109-2136 (United States)

    2005-02-02

    We review the sequences of structural states that can be induced in colloidal suspensions by the application of flow. Structure formation during flow is strongly affected by the delicate balance among interparticle forces, Brownian motion and hydrodynamic interactions. The resulting non-equilibrium microstructure is in turn a principal determinant of the suspension rheology. Colloidal suspensions with near hard-sphere interactions develop an anisotropic, amorphous structure at low dimensionless shear rates. At high rates, clustering due to strong hydrodynamic forces leads to shear thickening rheology. Application of steady-shear flow to suspensions with repulsive interactions induces a rich sequence of transitions to one-, two-and three-dimensional order. Oscillatory-shear flow generates metastable ordering in suspensions with equilibrium liquid structure. On the other hand, short-range attractive interactions can lead to a fluid-to-gel transition under quiescent suspensions. Application of flow leads to orientation, breakup, densification and spatial reorganization of aggregates. Using a non-Newtonian suspending medium leads to additional possibilities for organization. We examine the extent to which theory and simulation have yielded mechanistic understanding of the microstructural transitions that have been observed. (topical review)

  13. Polymeric nanoparticles for optical sensing.

    Science.gov (United States)

    Canfarotta, Francesco; Whitcombe, Michael J; Piletsky, Sergey A

    2013-12-01

    Nanotechnology is a powerful tool for use in diagnostic applications. For these purposes a variety of functional nanoparticles containing fluorescent labels, gold and quantum dots at their cores have been produced, with the aim of enhanced sensitivity and multiplexing capabilities. This work will review progress in the application of polymeric nanoparticles in optical diagnostics, both for in vitro and in vivo detection, together with a discussion of their biodistribution and biocompatibility. © 2013.

  14. Synthesis of polystyrene with high melting temperature through BDE/CuCl catalyzed polymerization

    Institute of Scientific and Technical Information of China (English)

    WAN; Xiaolong

    2001-01-01

    Lecomte, P., Drapier, I., Dubios, P. et al., Controlled radical polymerization of methyl methacrylate in the presence of palladium acetate, triphenyl phosphine, and carbon tetrachloride, Macromolecules, 1997, 30: 7631.[12]Kotani, Y., Kamigaito, Y., Sawamoto, M., Re(V)-mediated living radical polymerization of styrene: ReO2I(PPh3)2/RI initiating system, Macromolecules, 1999, 32: 2420.[13]Makino, T., Tokunaga, E., Hogen-Esch, T. E., Controlled atom transfer radical polymerizations of methyl methacrylate under micellar conditions, Polym. Prep., 1998, 39(1): 288.[14]Gaynor, S. G., Qiu, J., Matyjaszewski, K., Controlled/"living" radical polymerization applied to water-borne system, Macromolecule, 1998, 31: 5951.[15]Qiu, J., Gaynor, S. G., Matyjaszewski, K., Controlled/"living" radical polymerization of n-butyl methacrylate by reverse atom transfer radical polymerization, Macromolecules, 1999, 32: 2872.[16]Shipp, D. A., McMurtry, G. P., Gaynor, S. G. et al., Water-borne block copolymer synthesis and a simple and effective one-pot synthesis of acrylate-methacrylate block copolymers by atom transfer radical polymerization, Polym. Prep., 1999, 40(2): 448.[17]Nishikawa, T., Kamigaito, M., Sawamoto, M., Living radical polymerization in water and alcohols: suspension polymerization of methyl methacrylate with RuCl2(PPh3)3 complex, Macromolecules, 1999, 32: 2204.[18]Wan, X. L., Ying, S. K., "Living" radical emulsion polymerization of styrene under Cu0/Bpy/CCl4 and CuCl2/Bpy/AIBN system, Chinese J. Polym. Sci., 2000, (1): 27.[19]Wan, X. L., Ying, S. K., Controlled radical polymerization catalyzed by Cu/BDE complex in water medium, 1. Polymerization of styrene and synthesis of poly(St-b-MMA), J. Appl. Polym. Sci., 2000, 75(1): 802.[20]Wan, X. L., Ying, S. K., Synthesis of block copolymers by emulsion "living"/controlled radical polymerization of vinyl monomers in sequence, Polym. Prep., 1999, 40: 1055.[21]Keller, R. N., Wycoff, H. D., The synthesis

  15. The Synthesis of Carborane-Oxetane Monomers and their Polymerization

    Science.gov (United States)

    1988-07-11

    polyether glycol was liter demonstrated.’ During this time, " modified cationic polymerization technique was developef’, which allowed the synthesis of...Migration of these chemicals in the propellant grain is a continuous and serious problem. We proposed that a urethane curable polyether glycol with a...Br CH3 g 3 Cl CH3 This scheme has the advantage that the leaving group is not on the oxetane. Oxetane is a neopentyl type system which is typically

  16. Polymeric Coatings for Combating Biocorrosion

    Science.gov (United States)

    Guo, Jing; Yuan, Shaojun; Jiang, Wei; Lv, Li; Liang, Bin; Pehkonen, Simo O.

    2018-03-01

    Biocorrosion has been considered as big trouble in many industries and marine environments due to causing great economic loss. The main disadvantages of present approaches to prevent corrosion include being limited by environmental factors, being expensive, inapplicable to field, and sometimes inefficient. Studies show that polymer coatings with anti-corrosion and anti-microbial properties have been widely accepted as a novel and effective approach to preventbiocorrosion. The main purpose of this review is to summarize up the progressive status of polymer coatings used for combating microbially-induced corrosion. Polymers used to synthesize protective coatings are generally divided into three categories: i) traditional polymers incorporated with biocides, ii) antibacterial polymers containing quaternary ammonium compounds, and iii) conductive polymers. The strategies to synthesize polymer coatings resort mainly to grafting anti-bacterial polymers from the metal substrate surface using novel surface-functionalization approaches, such as free radical polymerization, chemically oxidative polymerization and surface-initiated atom transfer radical polymerization, as opposed to the traditional approaches of dip coating or spin coating.

  17. Non-equilibrium supramolecular polymerization.

    Science.gov (United States)

    Sorrenti, Alessandro; Leira-Iglesias, Jorge; Markvoort, Albert J; de Greef, Tom F A; Hermans, Thomas M

    2017-09-18

    Supramolecular polymerization has been traditionally focused on the thermodynamic equilibrium state, where one-dimensional assemblies reside at the global minimum of the Gibbs free energy. The pathway and rate to reach the equilibrium state are irrelevant, and the resulting assemblies remain unchanged over time. In the past decade, the focus has shifted to kinetically trapped (non-dissipative non-equilibrium) structures that heavily depend on the method of preparation (i.e., pathway complexity), and where the assembly rates are of key importance. Kinetic models have greatly improved our understanding of competing pathways, and shown how to steer supramolecular polymerization in the desired direction (i.e., pathway selection). The most recent innovation in the field relies on energy or mass input that is dissipated to keep the system away from the thermodynamic equilibrium (or from other non-dissipative states). This tutorial review aims to provide the reader with a set of tools to identify different types of self-assembled states that have been explored so far. In particular, we aim to clarify the often unclear use of the term "non-equilibrium self-assembly" by subdividing systems into dissipative, and non-dissipative non-equilibrium states. Examples are given for each of the states, with a focus on non-dissipative non-equilibrium states found in one-dimensional supramolecular polymerization.

  18. Prevalence of pesticides in postconsumer agrochemical polymeric packaging.

    Science.gov (United States)

    Eras, J; Costa, J; Vilaró, F; Pelacho, A M; Canela-Garayoa, R; Martin-Closas, L

    2017-02-15

    Pesticide remains contained in agrochemical packaging waste are a source of uncontrolled risk for human health; they are also a quality feedstock for the plastic recycling industry. Many governments have recently started to establish laws and regulations to develop systems for recovering and recycling the polymeric packages used for pesticides. There is also a demand in having a procedure to control the suitability of the pesticide packages to be reused. We have developed a two-step operation process to assess the pesticide residues in agricultural containers made of a variety of polymeric matrices. The procedure is based on an extraction with a solvent mixture followed by UPLC-MS/MS determination. Solvents for neutral pesticides were selected considering the Hildebrand solubility (δ) of solvents and polymers together with those estimated for the pesticides. The proposed technique is effective in recovering imbibed pesticides in polymeric matrices. Also, a simplified extraction procedure has been tested to become a routine method for these wastes. We have found that in many cases a significant amount of pesticides remain into the polymeric matrix, even after a standardized cleaning; the impact of releasing these hazardous compounds into the environment is to be of further consideration. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. In situ polymerization of vinyl monomers in polyester yarns

    International Nuclear Information System (INIS)

    Avny, Y.; Rebenfeld, L.; Weigmann, H.D.

    1978-01-01

    The effects of a pretreatment of polyester (PET) yarns with a strongly interacting solvent such as dimethylformamide (DMF) on vinyl monomer incorporation were investigated. When the DMF pretreatment is carried out at high temperatures (above 120 0 C), the swollen PET structure is stabilized by solvent-induced secondary crystallization. This substrate is highly suitable for the incorporation of vinyl monomers. In situ polymerization of vinyl monomers in DMF-treated PET was investigated using chemical and γ-irradiation polymerization techniques, both in the presence and in the absence of excess monomer outside the PET fibers. When polymerization was carried out in a system in which a constant supply of free radicals was available from the outside of the PET fibers, lower initiator concentrations and smaller γ-irradiation doses were necessary. These results are attributed to a low efficiency of the initiator inside the PET fiber due to mobility restrictions. Water uptake and moisture regain of PET yarns containing poly(hydroxyethyl methacrylate) and poly(acrylic acid) were also investigated. When most of the vinyl polymer was inside the PET fiber, water absorption was limited. The changes in mechanical properties of the PET yarns resulting from the DMF pretreatment were partially reversed by in situ polymerization of vinyl monomers

  20. Polythiophene films obtained by polymerization under atmospheric pressure plasma conditions

    Energy Technology Data Exchange (ETDEWEB)

    Teslaru, T.; Topala, I., E-mail: ionut.topala@uaic.ro; Dobromir, M.; Pohoata, V.; Curecheriu, L.; Dumitrascu, N.

    2016-02-01

    The present work describes the experimental arrangement used to initiate polymerization reactions of thiophene monomer based on a dielectric barrier discharge with plane – parallel geometry, working at atmospheric pressure in argon, in turn to obtain conductive polymeric films for different applications. The resulting plasma polymerized polythiophene (pPTh) film was characterized by FT-IR, UV–Vis, XPS spectroscopy, AFM and contact angle measurements. Characterization of pPTh films showed a higher hydrophobic character and roughness, as compared with films obtained by chemical methods, and the thickness is depending on polymerization duration. Also it can conclude that our samples represent oxidised state of pPTh. As a possible application, it analysed in situ the iodine absorption phenomenon in the pPTh matrix and its time evolution by UV–Vis spectroscopy. The presence of iodine 3d{sub 5/2} and 3d{sub 3/2} peaks in the pPTh sample after absorption was identified by XPS spectroscopy. The hydrophobic pPTh film is transformed in a super hydrophilic film after absorption of iodine vapors. - Highlights: • We obtained polythiophene films (pPTh) by atmospheric pressure plasma technique. • The pPTh films showed a hydrophobic character and conducting properties. • The pPTh films were used as sensor for iodine vapors in biological environment.

  1. Polyethylene-waste tire dust composites via in situ polymerization

    International Nuclear Information System (INIS)

    Reyes A, Y. K.; Narro C, R. I.; Ramos A, M. E.; Neira V, M. G.; Diaz E, J.; Enriquez M, F.; Valencia L, L. A.; Saade C, H.; Diaz de L, R.

    2014-01-01

    Polyethylene/waste tire dust (WTD) composites were obtained by an in situ polymerization technique. The surface of the WTD was modified with deposition of polyethylene by using plasma polymerization. Ethylene polymerization was carried out using bis(cyclopentadienyl) titanium dichloride (Cp 2 TiCl 2 ) as homogeneous metallocenes catalyst, while diethylaluminum chloride (DEAC), ethyl aluminum sesquichloride (EASC) and methyl alumino xane (Mao) were used as co-catalysts at two different [Al]/[Ti] molar ratio. The main characteristics of the obtained polyethylenes were determined by size exclusion chromatography, thermogravimetric analysis, differential scanning calorimetry and wide-angle X-ray diffraction. The results showed that by using EASC and Mao the highest catalytic activities were presented at a [Al]/[Ti] molar ratio of 9.17 and 18.33 respectively. Even though it was possible to obtain polyethylene using WTD (modified or unmodified) the catalytic activity was lower than in the case in which no WTD was added in ethylene polymerization. Scanning transmission electronic microscopy images evidenced that the original morphology of the polyethylenes was not modified by the presence of WTD. (Author)

  2. Polyethylene-waste tire dust composites via in situ polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Reyes A, Y. K.; Narro C, R. I.; Ramos A, M. E. [Universidad Autonoma de Coahuila, Facultad de Ciencias Quimicas, Blvd. Venustiano Carranza s/n, 25280 Saltillo, Coahuila (Mexico); Neira V, M. G.; Diaz E, J.; Enriquez M, F.; Valencia L, L. A.; Saade C, H.; Diaz de L, R., E-mail: ramon.diazdeleon@ciqa.edu.mx [Centro de Investigacion en Quimica Aplicada, Blvd. Enrique Reyna Hermosillo No. 40, Col. San Jose de los Cerritos, 25293 Saltillo, Coahuila (Mexico)

    2014-10-01

    Polyethylene/waste tire dust (WTD) composites were obtained by an in situ polymerization technique. The surface of the WTD was modified with deposition of polyethylene by using plasma polymerization. Ethylene polymerization was carried out using bis(cyclopentadienyl) titanium dichloride (Cp{sub 2}TiCl{sub 2}) as homogeneous metallocenes catalyst, while diethylaluminum chloride (DEAC), ethyl aluminum sesquichloride (EASC) and methyl alumino xane (Mao) were used as co-catalysts at two different [Al]/[Ti] molar ratio. The main characteristics of the obtained polyethylenes were determined by size exclusion chromatography, thermogravimetric analysis, differential scanning calorimetry and wide-angle X-ray diffraction. The results showed that by using EASC and Mao the highest catalytic activities were presented at a [Al]/[Ti] molar ratio of 9.17 and 18.33 respectively. Even though it was possible to obtain polyethylene using WTD (modified or unmodified) the catalytic activity was lower than in the case in which no WTD was added in ethylene polymerization. Scanning transmission electronic microscopy images evidenced that the original morphology of the polyethylenes was not modified by the presence of WTD. (Author)

  3. X-ray initiated polymerization of wood impregnants

    Energy Technology Data Exchange (ETDEWEB)

    Cleland, Marshall R.; Galloway, Richard A. [IBA Industrial, Inc., Edgewood, NY (United States); Berejka, Anthony J. [Ionicorp, Huntington, NY 11743 (United States)], E-mail: berejka@msn.com; Montoney, Daniel [Strathmore Products, Syracuse, NY (United States); Driscoll, Mark; Smith, Leonard; Scott Larsen, L. [State University of New York, SUNY-ESF, Syracuse, NY (United States)

    2009-07-15

    X-rays, derived from a high energy, high-current electron beam (EB), initiated in-situ polymerization of a unique class of monomers that were found to penetrate the cell walls of wood. X-rays initiated an auto-catalytic acrylic polymerization and penetrated through thick pieces of wood. The final cured product having the polymerizate, a polymer, both in the wood cell lumens and in the cell walls is called wood impregnated with a wood-polymer penetrant (WPP). The controlled lower dose rate of X-rays overcame disproportionation encountered when using higher dose-rate electron beam initiation. With X-rays, the in-situ polymerization took place in one exposure of modest dose. With EB, multiple passes were needed to avoid excessive heat build-up and monomer volatilization. Having entered the cell walls of the wood and then being polymerized within the cell walls, these radiation-cured unique monomers imparted outstanding dimensional stability upon exposure of the impregnated wood to humidity cycling. The preferred monomer system was also chemically modified prior to impregnation with agents that would remain in the wood and prevent the growth of fungi and other microbials. This technique differs from historic uses of monomers that merely filled the lumens of the wood (historic wood-polymer composites), which are only suitable for indoor use. The WPP impregnated wood that was either X-ray cured or EB cured demonstrated enhanced structural properties, dimensional stability, and decay resistance.

  4. X-ray initiated polymerization of wood impregnants

    International Nuclear Information System (INIS)

    Cleland, Marshall R.; Galloway, Richard A.; Berejka, Anthony J.; Montoney, Daniel; Driscoll, Mark; Smith, Leonard; Scott Larsen, L.

    2009-01-01

    X-rays, derived from a high energy, high-current electron beam (EB), initiated in-situ polymerization of a unique class of monomers that were found to penetrate the cell walls of wood. X-rays initiated an auto-catalytic acrylic polymerization and penetrated through thick pieces of wood. The final cured product having the polymerizate, a polymer, both in the wood cell lumens and in the cell walls is called wood impregnated with a wood-polymer penetrant (WPP). The controlled lower dose rate of X-rays overcame disproportionation encountered when using higher dose-rate electron beam initiation. With X-rays, the in-situ polymerization took place in one exposure of modest dose. With EB, multiple passes were needed to avoid excessive heat build-up and monomer volatilization. Having entered the cell walls of the wood and then being polymerized within the cell walls, these radiation-cured unique monomers imparted outstanding dimensional stability upon exposure of the impregnated wood to humidity cycling. The preferred monomer system was also chemically modified prior to impregnation with agents that would remain in the wood and prevent the growth of fungi and other microbials. This technique differs from historic uses of monomers that merely filled the lumens of the wood (historic wood-polymer composites), which are only suitable for indoor use. The WPP impregnated wood that was either X-ray cured or EB cured demonstrated enhanced structural properties, dimensional stability, and decay resistance.

  5. Analysis of an industrial production suspension of Bacillus lentus subtilisin crystals by powder diffraction: a powerful quality-control tool

    DEFF Research Database (Denmark)

    Frankær, Christian Grundahl; Moroz, Olga V.; Turkenburg, Johan P.

    2014-01-01

    . A controlled crystallization experiment with a highly purified Savinase sample allowed the growth of single crystals of the form identified by XRPD; their structure was solved and refined to a resolution of 1.17 Å with an R of 9.2% and an Rfree of 11.8%. Thus, there are at least three polymorphs present...... in the production suspension, albeit with the 1ndq -like microcrystals predominating. It is shown how the two techniques can provide invaluable and complementary information for such a production suspension and it is proposed that XRPD provides an excellent quality-control tool for such suspensions....

  6. Inclusion polymerization of vinyl chloride monomer in deoxycholic acid host via γ-ray irradiation

    International Nuclear Information System (INIS)

    Chirachanchai, S.; Kumkrong, A.; Ishida, Hatsuo

    2000-01-01

    Inclusion polymerization of vinyl chloride monomer (VCM) was studied in the system of 3α, 12α -dihydroxy-5β-cholan-24-oic acid (deoxycholic acid, DCA). DCA-VCM inclusion compound system was originally prepared by guest intercalation technique in DCA guest free crystal. The inclusion polymerization of DCA-VCM by γ-irradiation at total dose 2 Mrad, gives a syndiotactic rich polyvinyl chloride (PVC) as can be confirmed by FT-IR and FT-NMR. (author)

  7. Inclusion polymerization of vinyl chloride monomer in deoxycholic acid host via {gamma}-ray irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Chirachanchai, S.; Kumkrong, A. [The Petroleum and Petrochemical College, Chulalongkorn University, Bangkok (Thailand); Ishida, Hatsuo [Department of Macromolecular Science, Case Western Reserve University, Cleveland, OH (United States)

    2000-03-01

    Inclusion polymerization of vinyl chloride monomer (VCM) was studied in the system of 3{alpha}, 12{alpha} -dihydroxy-5{beta}-cholan-24-oic acid (deoxycholic acid, DCA). DCA-VCM inclusion compound system was originally prepared by guest intercalation technique in DCA guest free crystal. The inclusion polymerization of DCA-VCM by {gamma}-irradiation at total dose 2 Mrad, gives a syndiotactic rich polyvinyl chloride (PVC) as can be confirmed by FT-IR and FT-NMR. (author)

  8. Formulation and Characterization of Pyrazinamide Polymeric Nanoparticles for Pulmonary Tuberculosis: Efficiency for Alveolar Macrophage Targeting

    OpenAIRE

    Varma, J. N. Ravi; Kumar, T. Santosh; Prasanthi, B.; Ratna, J. Vijaya

    2015-01-01

    Pyrazinamide, a highly specific agent against Mycobacterium tuberculosis is used as first-line drug to treat tuberculosis. The current work aims to formulate polymeric nanoparticles based drug delivery system to sustain the release profile and reduce the dosing frequency of pyrazinamide. Further aim was to target the macrophages within body fluid. These polymeric nanoparticles were prepared by simultaneous double-emulsion (W/O/W) solvent evaporation/diffusion technique. The prepared dispersio...

  9. Chitin nanofiber elucidates the elicitor activity of polymeric chitin in plants

    Directory of Open Access Journals (Sweden)

    Mayumi eEgusa

    2015-12-01

    Full Text Available Chitin, an N-acetyl-D-glucosamine polymer, is a component of fungal cell walls and a microbe/pathogen-associated molecular pattern that elicits plant defense responses. As polymeric chitin is difficult to handle due to its insolubility in water, many studies on chitin-induced immune responses have used water-soluble low-molecular weight chitin instead. Thus, it is unclear if polymeric chitin can induce resistance. Here, we examined the elicitor activity of chitin nanofiber (CNF of submicron thickness prepared from polymeric chitin. CNF showed a high dispersing ability in water and induced both reactive oxygen species (ROS production and chitin-induced defense-related gene expression in Arabidopsis thaliana seedlings. The Arabidopsis chitin elicitor receptor kinase 1 (Atcerk1 mutant, which is impaired in chitin perception, also failed to respond to CNF. CNF exposure triggered ROS generation in suspension-cultured cells from Oryza sativa. Furthermore, pre-treatment of Arabidopsis leaves with CNF effectively reduced pathogen infection by both the fungus Alternaria brassicicola and the bacterium Pseudomonas syringae pv. tomato DC3000. These results demonstrate that CNF has elicitor activity and will help define the role of polymeric chitin in plant immune responses.

  10. Facts and evidences on the lyophilization of polymeric nanoparticles for drug delivery.

    Science.gov (United States)

    Fonte, Pedro; Reis, Salette; Sarmento, Bruno

    2016-03-10

    Lyophilization has been used to improve the long-term stability of polymeric nanoparticles for drug delivery applications, avoiding their instability in suspension. However, this dehydration process may induce stresses to nanoparticles, mitigated by the use of some excipients such as cryo- and lyoprotectants. Still, the lyophilization of polymeric nanoparticles is frequently based in empirical principles, without considering the physical-chemical properties of formulations and the engineering principles of lyophilization. Therefore, the optimization of formulations and the lyophilization cycle is crucial to obtain a good lyophilizate, and guarantee the preservation of nanoparticle stability. The proper characterization of the lyophilizate and nanoparticles has a great importance in achieving these purposes. This review updates the fundaments involved in the optimization procedures for lyophilization of polymeric nanoparticles, with the aim of obtaining the maximum stability of formulations. Different characterization methods to obtain and guarantee a good lyophilized product are also discussed. A special focus is given to encapsulated therapeutic proteins. Overall, this review is a contribution for the understanding of the parameters involved in the lyophilization of polymeric nanoparticles. This may definitely help future works to obtain lyophilized nanoparticles with good quality and with improved therapeutic benefits. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Preparation of Water Suspensions of Nanocalcite for Cultural Heritage Applications

    Directory of Open Access Journals (Sweden)

    Maria-Beatrice Coltelli

    2018-04-01

    Full Text Available The consolidation of degraded carbonate stone used in ancient monuments is an important topic for European cultural heritage conservation. The products most frequently used as consolidants are based on tetraalkoxy- or alkylalkoxy-silanes (in particular tetraethyl-orthosilicate, TEOS, resulting in the formation of relatively stable amorphous silica or alkylated (hydrophobic silica inside the stone pores. However, silica is not chemically compatible with carbonate stones; in this respect, nanocalcite may be a suitable alternative. The present work concerns the preparation of water suspensions of calcite nanoparticles (CCNPs by controlled carbonation of slaked lime using a pilot-scale reactor. A simplified design of experiment was adopted for product optimization. Calcite nanoparticles of narrow size distribution averaging about 30 nm were successfully obtained, the concentration of the interfacial agent and the size of CaO being the most critical parameters. Primary nanoparticle aggregation causing flocculation could be substantially prevented by the addition of polymeric dispersants. Copolymer-based dispersants were produced in situ by controlled heterophase polymerisation mediated by an amphiphilic macro-RAFT (reversible addition-fragmentation transfer agent. The stabilized CCNP aqueous dispersions were then applied on carbonate and silicate substrates; Scanning Electron Microscopy (SEManalysis of cross-sections allowed the evaluation of pore penetration, interfacial binding, and bridging (gap-filling properties of these novel consolidants.

  12. DESIGN AND APPLICATION OF MAGNETIC BEARING SUSPENSION SYSTEM IN A THREE PHASE INDUCTION MOTOR

    Directory of Open Access Journals (Sweden)

    Osman GÜRDAL

    1998-03-01

    Full Text Available The current popularity of suspension and levitation stems no doubt the possibilities in high-speed ground transportation schemes. Although these are both challenging and exciting, there is considerable scope for application of suspension techniques to achieving frictionless bearing. The requirement in this case is often for close tolerances, low power consumption, small airgaps and ingeneral, compactness. Thus, magnetic suspension using DC electromagnets schemes have received more attention than the other techniques of repulsion levitation. Proposed prototype system consists of a conventional stator and its rotor without iron core, set of electromagnets for suspension of rotor shaft and set of compensation circuits feedbacked by optical-transducers. Prototyped system is aimed as a laboratory demonstration tool so there is no challenging to exceed the speeds of 1500 rev/min that is the speed of motor with mechanical bearings. Magnetic bearing suspension system provides a high impact visual demonstration of many principles in undergraduate educational programs in electrical education, e.g., electromagnetic design, PD controlled compensation of a unstable control system and power amplifier design. The system is capable of giving a good comparison between mechanical and magnetic bearing up to speeds 350 rev/min. Power losses without load show about 15% reduction with magnetic bearing. The noise of the motor is also decreased to a low level.

  13. Simultaneous measurement of polymerization stress and curing kinetics for photo-polymerized composites with high filler contents.

    Science.gov (United States)

    Wang, Zhengzhi; Landis, Forrest A; Giuseppetti, Anthony A M; Lin-Gibson, Sheng; Chiang, Martin Y M

    2014-12-01

    Photopolymerized composites are used in a broad range of applications with their performance largely directed by reaction kinetics and contraction accompanying polymerization. The present study was to demonstrate an instrument capable of simultaneously collecting multiple kinetics parameters for a wide range of photopolymerizable systems: degree of conversion (DC), reaction exotherm, and polymerization stress (PS). Our system consisted of a cantilever beam-based instrument (tensometer) that has been optimized to capture a large range of stress generated by lightly-filled to highly-filled composites. The sample configuration allows the tensometer to be coupled to a fast near infrared (NIR) spectrometer collecting spectra in transmission mode. Using our instrument design, simultaneous measurements of PS and DC are performed, for the first time, on a commercial composite with ≈80% (by mass) silica particle fillers. The in situ NIR spectrometer collects more than 10 spectra per second, allowing for thorough characterization of reaction kinetics. With increased instrument sensitivity coupled with the ability to collect real time reaction kinetics information, we show that the external constraint imposed by the cantilever beam during polymerization could affect the rate of cure and final degree of polymerization. The present simultaneous measurement technique is expected to provide new insights into kinetics and property relationships for photopolymerized composites with high filler content such as dental restorative composites. Published by Elsevier Ltd.

  14. 21 CFR 1301.36 - Suspension or revocation of registration; suspension of registration pending final order...

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Suspension or revocation of registration; suspension of registration pending final order; extension of registration pending final order. 1301.36... registration pending final order; extension of registration pending final order. (a) For any registration...

  15. Suspension, a Wake-Up Call: Rural Educators' Attitudes toward Suspension.

    Science.gov (United States)

    Henderson, Joan; Friedland, Billie

    Data from the West Virginia Department of Education reveals that from September 1991 to January 1992, school districts reported 18,915 out-of-school suspensions involving 12,997 students. In 1995, the West Virginia State Legislature enacted the Safe Schools Act, which specifically mandates suspension for no less than 12 consecutive months for…

  16. Nanoporous Polymeric Grating-Based Biosensors

    KAUST Repository

    Gao, Tieyu

    2012-05-02

    We demonstrate the utilization of an interferometrically created nanoporous polymeric gratings as a platform for biosensing applications. Aminopropyltriethoxysilane (APTES)-functionalized nanoporous polymeric gratings was fabricated by combining holographic interference patterning and APTES-functionalization of pre-polymer syrup. The successful detection of multiple biomolecules indicates that the biofunctionalized nanoporous polymeric gratings can act as biosensing platforms which are label-free, inexpensive, and applicable as high-throughput assays. Copyright © 2010 by ASME.

  17. Nanoporous Polymeric Grating-Based Biosensors

    KAUST Repository

    Gao, Tieyu; Hsiao, Vincent; Zheng, Yue Bing; Huang, Tony Jun

    2012-01-01

    We demonstrate the utilization of an interferometrically created nanoporous polymeric gratings as a platform for biosensing applications. Aminopropyltriethoxysilane (APTES)-functionalized nanoporous polymeric gratings was fabricated by combining holographic interference patterning and APTES-functionalization of pre-polymer syrup. The successful detection of multiple biomolecules indicates that the biofunctionalized nanoporous polymeric gratings can act as biosensing platforms which are label-free, inexpensive, and applicable as high-throughput assays. Copyright © 2010 by ASME.

  18. Volumetric polymerization shrinkage of contemporary composite resins

    OpenAIRE

    Nagem Filho, Halim; Nagem, Haline Drumond; Francisconi, Paulo Afonso Silveira; Franco, Eduardo Batista; Mondelli, Rafael Francisco Lia; Coutinho, Kennedy Queiroz

    2007-01-01

    The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill ...

  19. Surface modification of cation exchange membranes by graft polymerization of PAA-co-PANI/MWCNTs nanoparticles

    International Nuclear Information System (INIS)

    Nemati, Mahsa; Hosseini, Sayed Mohsen; Bagheripour, Ehsan; Madaeni, Sayed Siavash

    2016-01-01

    Surface modification of polyvinylchloride based heterogeneous cation exchange membrane was performed by graft polymerization of PAA and PAA-co-PANI/MWCNTs nanoparticles. The ion exchange membranes were prepared by solution casting technique. Spectra analysis confirmed graft polymerization clearly. SEM images illustrated that graft polymerization covers the membranes by simple gel network entanglement. The membrane water content was decreased by graft polymerization of PAA-co-PANI/MWCNTs nanoparticles on membrane surface. Membrane transport number and selectivity declined initially by PAA graft polymerization and then began to increase by utilizing of composite nanoparticles in modifier solution. The sodium and barium flux was improved sharply by PAA and PAAco- 0.01%wt PANI/MWCNTs graft polymerization on membrane surface and then decreased again by more increase of PANI/MWCNTs nanoparticles content ratio in modifier solution. The electrodialysis experiment results in laboratory scale showed higher dialytic rate in heavy metals removal for grafted-PAA and grafted-PAA-co-PANI/MWCNTs modified membrane compared to pristine one. Membrane areal electrical resistance was also decreased by introducing graft polymerization of PAA and PAA-co-PANI/MWCNTs NPs on membrane surface.

  20. Immobilization and continuous culture of cells with radiation polymerized supports for the uses of biomass conversion processes

    International Nuclear Information System (INIS)

    Kaetsu, I.; Kumakura, M.; Fujimura, T.; Tamada, M.; Kasai, N.

    1988-01-01

    A novel technique for immobilization and biofunctional components such as enzyme, antibody, protein, drug, hormone and organella by means of radiation polymerization was studied and developed. (E.G.) [pt

  1. Polymeric membrane materials for artificial organs.

    Science.gov (United States)

    Kawakami, Hiroyoshi

    2008-01-01

    Many polymeric materials have already been used in the field of artificial organs. However, the materials used in artificial organs are not necessarily created with the best material selectivity and materials design; therefore, the development of synthesized polymeric membrane materials for artificial organs based on well-defined designs is required. The approaches to the development of biocompatible polymeric materials fall into three categories: (1) control of physicochemical characteristics on material surfaces, (2) modification of material surfaces using biomolecules, and (3) construction of biomimetic membrane surfaces. This review will describe current issues regarding polymeric membrane materials for use in artificial organs.

  2. Numerical study of suspensions of deformable particles.

    Science.gov (United States)

    Brandt, Luca; Rosti, Marco Edoardo

    2017-11-01

    We consider a model non-Newtonian fluid consisting of a suspension of deformable particles in a Newtonian solvent. Einstein showed in his pioneering work that the relative increase in effective viscosity is a linear function of the particle volume fraction for dilute suspensions of rigid particles. Inertia has been shown to introduce deviations from the behaviour predicted by the different empirical fits, an effect that can be related to an increase of the effective volume fraction. We here focus on the effect of elasticity, i.e. visco-elastic deformable particles. To tackle the problem at hand, we perform three-dimensional Direct Numerical Simulation of a plane Couette flow with a suspension of neutrally buoyant deformable viscous hyper-elastic particles. We show that elasticity produces a shear-thinning effect in elastic suspensions (in comparison to rigid ones) and that it can be understood in terms of a reduction of the effective volume fraction of the suspension. The deformation modifies the particle motion reducing the level of mutual interaction. Normal stress differences will also be considered. European Research Council, Grant No. ERC-2013-CoG- 616186, TRITOS; SNIC (the Swedish National Infrastructure for Computing).

  3. Pitched Blade Turbine Efficiency at Particle Suspension

    Directory of Open Access Journals (Sweden)

    D. Ceres

    2010-01-01

    Full Text Available Mixing suspensions is a very important hydraulic operation. The pitched six-blade turbine is a widely-used axial-flow impeller. This paper deals with effect relative impeller size and particle content on theefficiency of a pitched six-blade turbine at particle suspension. Two pitched six-blade turbines were used in model measurements of just suspension impeller speed. The ratios of the vessel to agitator diameter D/d were 3 and 4.5. The measurements were carried out in a dish-bottomed vessel 300 mm in diameter. The just suspension impeller speeds were measured using an electrochemical method, and were checked visually. A 2.5 % NaCl water solution was used as the liquid phase, and glass particles with four equivalent diameters between 0.18 and 0.89 mmand volumetric concentration from 2.5 % to 40% were usedasthesolid phase. The criterion values πs=Po√Fr'3(d/D7 were calculated from the particle suspension and power consumption measurements. The dependencies of πs on particle content cv show that larger agitators are more efficient for higher particle content.

  4. CFD simulation of solids suspension in stirred tanks: Review

    Directory of Open Access Journals (Sweden)

    Ochieng Aoyi

    2010-01-01

    Full Text Available Many chemical reactions are carried out using stirred tanks, and the efficiency of such systems depends on the quality of mixing, which has been a subject of research for many years. For solid-liquid mixing, traditionally the research efforts were geared towards determining mixing features such as off-bottom solid suspension using experimental techniques. In a few studies that focused on the determination of solids concentration distribution, some methods that have been used have not been accurate enough to account for some small scale flow mal-distribution such as the existence of dead zones. The present review shows that computational fluid dynamic (CFD techniques can be used to simulate mixing features such as solids off-bottom suspension, solids concentration and particle size distribution and cloud height. Information on the effects of particle size and particle size distribution on the solids concentration distribution is still scarce. Advancement of the CFD modeling is towards coupling the physical and kinetic data to capture mixing and reaction at meso- and micro-scales. Solids residence time distribution is important for the design; however, the current CFD models do not predict this parameter. Some advances have been made in recent years to apply CFD simulation to systems that involve fermentation and anaerobic processes. In these systems, complex interaction between the biochemical process and the hydrodynamics is still not well understood. This is one of the areas that still need more attention.

  5. Immunocytochemical characterization of the cell walls of bean cell suspensions during habituation and dehabituation to dichlobenil

    DEFF Research Database (Denmark)

    Garcia-Angulo, P.; Willats, W. G. T.; Encina, A. E.

    2006-01-01

    The effects of the cellulose inhibitor dichlobenil on the cell wall composition and structure during the habituation/dehabituation process of suspension-cultured bean cells were assessed. A range of techniques were used including cell wall fractionation, sugar analysis, immunofluorescence...... and fluorochrome labelling of resin-embedded sections, and immunodot assays (IDAs) of cell wall fractions. The cell walls from bean cell suspensions with initial levels of habituation to dichlobenil had decreased levels of cellulose, but this effect lessened with increasing numbers of subcultures. All cell walls...

  6. Twin screw extruders as polymerization reactors for a free radical homo polymerization

    NARCIS (Netherlands)

    Ganzeveld, K.J.; Janssen, L.P.B.M.

    The bulk polymerization of n-butylmethacrylate was investigated in a counter-rotating twin screw extruder. It appeared that the gel effect, occurring with bulk polymerizations, affected the polymerization progress very strongly. Due to this effect the conversion of the reaction is independent of the

  7. Polymeric THz 2D Photonic Crystal Filters Fabricated by Fiber Drawing

    DEFF Research Database (Denmark)

    Stecher, Matthias; Jansen, Christian; Ahmadi-Boroujeni, Mehdi

    2012-01-01

    In this paper, we report on a new form of polymeric 2D photonic crystal filters for THz frequencies fabricated using a standard fiber drawing technique. The band stop filters were modeled and designed using the generalized multipole technique. The frequency and angle-dependent transmission...

  8. Thailand. Radiation-Polymerization in Thailand

    Energy Technology Data Exchange (ETDEWEB)

    Nilubol, M.L. Anong; Greethong, Somkiart [Office of Atomic Energy for Peace, Bangkok (Thailand)

    1968-10-15

    Wood-plastic composites produced by means of radiation-induced polymerization of monomers impregnated into the wood have been the subject of study in many laboratories throughout the world. In general the processes are similar, and the differences that occur are due to variations in technique applied to the particular species of wood available in each country. In Thailand, treatment to improve the quality of wood is being carried out by scientists at the Forest Products Research Division of the Royal Forest Department, Ministry of Agriculture, with the aim of obtaining products which can stand up to weathering and termite attack. On the basis of their experience, certain types of wood suitable for impregnation have been selected for our study. The Office of Atomic Energy for Peace began studying the impregnation-irradiation of certain types of Thai wood in the hope that it might result in better utilization of poor quality wood. The use of irradiated-impregnated wood in Thailand is not necessary at present, since many different varieties of hard wood are available. The production of plywood does not even meet the demand of the local market, thus the introduction of this new technique is not an attractive proposal for the time being.

  9. Modeling Suspension and Continuation of a Process

    Directory of Open Access Journals (Sweden)

    Oleg Svatos

    2012-04-01

    Full Text Available This work focuses on difficulties an analyst encounters when modeling suspension and continuation of a process in contemporary process modeling languages. As a basis there is introduced general lifecycle of an activity which is then compared to activity lifecycles supported by individual process modeling languages. The comparison shows that the contemporary process modeling languages cover the defined general lifecycle of an activity only partially. There are picked two popular process modeling languages and there is modeled real example, which reviews how the modeling languages can get along with their lack of native support of suspension and continuation of an activity. Upon the unsatisfying results of the contemporary process modeling languages in the modeled example, there is presented a new process modeling language which, as demonstrated, is capable of capturing suspension and continuation of an activity in much simpler and precise way.

  10. Phagocytosis in phosphate chromium (III) suspensions

    International Nuclear Information System (INIS)

    Cruz-Arencibia, Jorge; Fano Machín, Yoiz; Cruz-Morales, Ahmed; Tamayo Fuente, Radamés; Morín-Zorrilla, José

    2015-01-01

    Phagocytosis in vivo and in vitro of a suspension of chromic phosphate (III) labeled with 51 Cr and 32 P is studied. The radioactive particles dispersed in a media of 2 % gelatin in acetate buffer pH 4-4.5 have a predominant size of 0.8 μm and 5 μm. According with biodistribution experiments in rats after 30 minutes near the 80 % of radioactivity is registered in the liver, probably associated with phagocytosis of the particles by liver Kupffer cells. Is also showed that the suspension particles are phagocytized in vitro by mouse peritoneal macrophages. This facts indicate that the studied suspension have appropriate characteristics to be used in radiosynoviorthesis according to the principal action mechanism described for this procedure, particles phagocytosis by cells present in the inflamed synovium. (author)

  11. Crust formation in drying colloidal suspensions

    KAUST Repository

    Style, R. W.

    2010-06-30

    During the drying of colloidal suspensions, the desiccation process causes the suspension near the air interface to consolidate into a connected porous matrix or crust. Fluid transport in the porous medium is governed by Darcy\\'s law and the equations of poroelasticity, while the equations of colloid physics govern processes in the suspension. We derive new equations describing this process, including unique boundary conditions coupling the two regions, yielding a moving-boundary model of the concentration and stress profiles during drying. A solution is found for the steady-state growth of a nedimensional crust during constant evaporation rate from the surface. The solution is used to demonstrate the importance of the system boundary conditions on stress profiles and diffusivity in a drying crust. © 2011 The Royal Society.

  12. Aquaporin-Based Biomimetic Polymeric Membranes: Approaches and Challenges

    DEFF Research Database (Denmark)

    Habel, Joachim Erich Otto; Hansen, Michael; Kynde, Søren

    2015-01-01

    In recent years, aquaporin biomimetic membranes (ABMs) for water separation have gained considerable interest. Although the first ABMs are commercially available, there are still many challenges associated with further ABM development. Here, we discuss the interplay of the main components of ABMs...... thin film interfacial polymerization techniques. Finally, we describe some new developments in interfacial polymerization using polyhedral oligomeric silsesquioxane cages for increasing the physical and chemical durability of thin film composite membranes.......In recent years, aquaporin biomimetic membranes (ABMs) for water separation have gained considerable interest. Although the first ABMs are commercially available, there are still many challenges associated with further ABM development. Here, we discuss the interplay of the main components of ABMs...... for investigating AQP incorporation including freeze-fracture transmission electron microscopy, fluorescence correlation spectroscopy, stopped-flow light scattering, and small-angle X-ray scattering. Third, we focus on recent efforts in embedding reconstituted AQPs in membrane designs that are based on conventional...

  13. Radiolytic polymerization and some applications of obtained polymers

    International Nuclear Information System (INIS)

    Nizam El-Din, H.M.M.N.

    1996-01-01

    Hydrogles are considered as very interesting polymeric materials that find wide application in many fields. These fields include chromatography, biology and medicine, field of contact lenses, controlled release application and agriculture. However, most of the research work are devoted to synthesis these hydrogels using chemical techniques. In literature, a very limited information are available on radiation polymerization of corresponding monomer for hydrogel preparation. The present work is aim ming to synthesis a series of hydrogels based on ho moor co-polymer and to study the parameters affecting, these process. These parameters include radiation dose, type of monomer, type of solvent, concentration of crosslinking agent and liquor ratio. Besides, it is aimed to correlate the structure of these hydrogels with the efficiency for different metal ions recovery. Several chemicals and physical tools were used during this investigation including spectroscopic UV-Visible, Atomic absorption and IR), the mal analysis (TGA and DSc), magnetic and scanning electron microscope

  14. Radiolytic polymerization and some applications of obtained polymers

    International Nuclear Information System (INIS)

    Nizam El-Din, H.M.M.

    1996-01-01

    Hydrogels are considered as very interesting polymeric materials that find wide application in many fields. These fields include chromatography, biology and medicine, field of contact lenses, controlled release application and agriculture. However, most of the research work are devoted to synthesis these hydrogels using chemical techniques. In literature, a very limited information are available on radiation polymerization of corresponding monomer for hydrogel preparation. The present work is aiming to synthesis a series of hydrogels based on homoor co-polymer and to study the parameters affecting, these process. These parameters include radiation dose, type of monomer, type of solvent, concentration of crosslinking agent and liquor ratio. Besides, it is aimed to correlate the structure of these hydrogels with the efficiency for different metal ions recovery. Several chemicals and physical tools were used during this investigation including spectroscopic UV-Visible, Atomic absorption and IR), thermal analysis (TGA and DSC), magnetic and scanning electron microscope

  15. Development and characterization of polymeric membranes for water desalination

    International Nuclear Information System (INIS)

    Bresciani, Danusa; Guimaraes, Danilo H.; Santos, Diego K.M.; Brioude, Michel M.; Jose, Nadia M.; Prado, Luis A.S.A.

    2009-01-01

    This work reports a development of polymeric membranes for water desalination by reverse osmosis. The polyester was synthesized by the reaction between glycerol, and dicarboxylic acids, and was coded PAF. Cellulose acetate/PAF blends containing 10% and 30% of polyester PAF blends were prepared using compression molding. The materials were characterized by DRX, DSC, TGA and SEM techniques. The results blends showed good thermal resistance and thermal events due to the individual components of the blends. The membranes exhibited a good performance in comparison to the neat cellulose acetate membrane. The addition of PAF in the polyester composition of the polymeric blends caused a significant increase of the salt retention of the studied samples. (author)

  16. Aquaporin-Based Biomimetic Polymeric Membranes: Approaches and Challenges

    Science.gov (United States)

    Habel, Joachim; Hansen, Michael; Kynde, Søren; Larsen, Nanna; Midtgaard, Søren Roi; Jensen, Grethe Vestergaard; Bomholt, Julie; Ogbonna, Anayo; Almdal, Kristoffer; Schulz, Alexander; Hélix-Nielsen, Claus

    2015-01-01

    In recent years, aquaporin biomimetic membranes (ABMs) for water separation have gained considerable interest. Although the first ABMs are commercially available, there are still many challenges associated with further ABM development. Here, we discuss the interplay of the main components of ABMs: aquaporin proteins (AQPs), block copolymers for AQP reconstitution, and polymer-based supporting structures. First, we briefly cover challenges and review recent developments in understanding the interplay between AQP and block copolymers. Second, we review some experimental characterization methods for investigating AQP incorporation including freeze-fracture transmission electron microscopy, fluorescence correlation spectroscopy, stopped-flow light scattering, and small-angle X-ray scattering. Third, we focus on recent efforts in embedding reconstituted AQPs in membrane designs that are based on conventional thin film interfacial polymerization techniques. Finally, we describe some new developments in interfacial polymerization using polyhedral oligomeric silsesquioxane cages for increasing the physical and chemical durability of thin film composite membranes. PMID:26264033

  17. Micellar polymerization: Computer simulations by dissipative particle dynamics.

    Science.gov (United States)

    Shupanov, Ruslan; Chertovich, Alexander; Kos, Pavel

    2018-07-15

    Nowadays, micellar polymerization is widely used in different fields of industry and research, including modern living polymerization technique. However, this process has many variables and there is no comprehensive model to describe all features. This research presents simulation methodology which describes key properties of such reactions to take a guide through a variety of their modifications. Dissipative particle dynamics is used in addition to Monte Carlo scheme to simulate initiation, propagation, and termination events. Influence of initiation probability and different termination processes on final conversion and molecular-weight distribution are presented. We demonstrate that prolonged initiation leads to increasing in polymer average molecular weight, and surface termination events play major role in conversion limitation, in comparison with recombination. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

  18. Polyaniline-coated halloysite nanotubes via in-situ chemical polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Long [State Key Laboratory of Applied Organic Chemistry and Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Wang Tingmei [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Liu Peng [State Key Laboratory of Applied Organic Chemistry and Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China)], E-mail: pliu@lzu.edu.cn

    2008-12-30

    Polyaniline coated halloysite nanotubes (PANI/HNTs) were prepared by the in-situ soapless emulsion polymerization of the anilinium chloride adsorbed halloysite nanotubes (HNTs), obtained by the dispersion of HNTs in acidic aqueous solution of aniline with magnetic stirring and ultrasonic irradiation, by using ammonium persulfate (APS) as oxidant. The effect of the acidities of the polymerizing media on the crystal structure of the nanotubes was investigated with X-ray diffraction (XRD) technique. The surface conducting coatings of the hybrids were characterized with X-ray photoelectron spectroscopy (XPS). The morphological analyses showed that the polyaniline coated halloysite nanotubes via the in-situ chemical oxidation polymerization with ultrasonic irradiation had the better well-defined structures, by the transmission electron microscopy (TEM). The conductivities of the PANI/HNTs hybrids increased with the increasing of the amounts of HCl dopant added in the emulsion polymerization.

  19. Site-selective metallization of polymeric substrates by the hyperbranched polymer templates

    International Nuclear Information System (INIS)

    Li, Peiyuan; Yang, Fang; Li, Xiangcheng; He, Chunling; Su, Wei; Chen, Jinhao; Huo, Lini; Chen, Rui; Lu, Chensheng; Liang, Lifang

    2013-01-01

    We demonstrate a simple, cost-effective and universal technique for the fabrication of copper circuit pattern on flexible polymeric substrate. This method relies on a ternary polyethylenimine-poly(acrylic acid)-substrate film incorporating palladium catalysts, which are used as adhesive interlayers for the copper metallization of flexible polymeric substrates. We demonstrated the fabrication of patterned copper films on a variety of flexible polymers with minimum feature sizes of 200 μm. And the resulting copper circuit showed strong adhesion with underlying flexible polymeric substrates. The films were characterized by ATR FT-IR, contact angle, XPS, XRD, TEM and SEM. The direct patterning of metallic circuit on flexible polymeric substrate indicates great potential for the use in electronics industry.

  20. Site-selective metallization of polymeric substrates by the hyperbranched polymer templates

    Energy Technology Data Exchange (ETDEWEB)

    Li, Peiyuan, E-mail: lipearpear@163.com [College of Pharmacy, Guangxi University of Chinese Medicine, Nanning 530001 (China); Yang, Fang [College of Chemistry and Life Science, Guangxi Teachers Education University, Nanning 530001 (China); Li, Xiangcheng [School of Computer, Electronics and Information, Guangxi University, Nanning 530001 (China); He, Chunling [College of Pharmacy, Guangxi University of Chinese Medicine, Nanning 530001 (China); Su, Wei, E-mail: suwmail@163.com [College of Chemistry and Life Science, Guangxi Teachers Education University, Nanning 530001 (China); Chen, Jinhao [College of Chemistry and Life Science, Guangxi Teachers Education University, Nanning 530001 (China); Huo, Lini; Chen, Rui; Lu, Chensheng [College of Pharmacy, Guangxi University of Chinese Medicine, Nanning 530001 (China); Liang, Lifang [College of Chemistry and Life Science, Guangxi Teachers Education University, Nanning 530001 (China)

    2013-09-01

    We demonstrate a simple, cost-effective and universal technique for the fabrication of copper circuit pattern on flexible polymeric substrate. This method relies on a ternary polyethylenimine-poly(acrylic acid)-substrate film incorporating palladium catalysts, which are used as adhesive interlayers for the copper metallization of flexible polymeric substrates. We demonstrated the fabrication of patterned copper films on a variety of flexible polymers with minimum feature sizes of 200 μm. And the resulting copper circuit showed strong adhesion with underlying flexible polymeric substrates. The films were characterized by ATR FT-IR, contact angle, XPS, XRD, TEM and SEM. The direct patterning of metallic circuit on flexible polymeric substrate indicates great potential for the use in electronics industry.

  1. Polyaniline-coated halloysite nanotubes via in-situ chemical polymerization

    International Nuclear Information System (INIS)

    Zhang Long; Wang Tingmei; Liu Peng

    2008-01-01

    Polyaniline coated halloysite nanotubes (PANI/HNTs) were prepared by the in-situ soapless emulsion polymerization of the anilinium chloride adsorbed halloysite nanotubes (HNTs), obtained by the dispersion of HNTs in acidic aqueous solution of aniline with magnetic stirring and ultrasonic irradiation, by using ammonium persulfate (APS) as oxidant. The effect of the acidities of the polymerizing media on the crystal structure of the nanotubes was investigated with X-ray diffraction (XRD) technique. The surface conducting coatings of the hybrids were characterized with X-ray photoelectron spectroscopy (XPS). The morphological analyses showed that the polyaniline coated halloysite nanotubes via the in-situ chemical oxidation polymerization with ultrasonic irradiation had the better well-defined structures, by the transmission electron microscopy (TEM). The conductivities of the PANI/HNTs hybrids increased with the increasing of the amounts of HCl dopant added in the emulsion polymerization.

  2. A Self-Reporting Photocatalyst for Online Fluorescence Monitoring of High Throughput RAFT Polymerization.

    Science.gov (United States)

    Yeow, Jonathan; Joshi, Sanket; Chapman, Robert; Boyer, Cyrille Andre Jean Marie

    2018-04-25

    Translating controlled/living radical polymerization (CLRP) from batch to the high throughput production of polymer libraries presents several challenges in terms of both polymer synthesis and characterization. Although recently there have been significant advances in the field of low volume, high throughput CLRP, techniques able to simultaneously monitor multiple polymerizations in an "online" manner have not yet been developed. Here, we report our discovery that 5,10,15,20-tetraphenyl-21H,23H-porphine zinc (ZnTPP) is a self-reporting photocatalyst that can mediate PET-RAFT polymerization as well as report on monomer conversion via changes in its fluorescence properties. This enables the use of a microplate reader to conduct high throughput "online" monitoring of PET-RAFT polymerizations performed directly in 384-well, low volume microtiter plates. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Oligonucleotides as probes for studying polymerization reactions in dilute aqueous solution

    Science.gov (United States)

    Kolb, V.; Orgel, L. E.; Miller, S. L. (Principal Investigator)

    1994-01-01

    We have prepared a [32P]-labled oligonucleotide probe carrying a free primary amine at its 3'-terminus. This probe is used to initiate polymerization of aziridine (ethyleneimine) in aqueous solution. The nature of the oligomeric products and the kinetics of their formation are then monitored by gel electrophoresis. Our results are generally consistent with those obtained using conventional techniques. We have also investigated the effect of polyanionic templates on the rate of oligomerization of aziridine. We find that water-soluble polyanions generally accelerate the polymerization. The sodium salt of polymethacrylic acid is the most effective of the templates that we studied. The methods introduced in this paper should be applicable to a variety of polymerization reactions in aqueous solution. They should greatly simplify the screening of potentially prebiotic polymerization reactions.

  4. Micromechanical exfoliation of two-dimensional materials by a polymeric stamp

    International Nuclear Information System (INIS)

    Costa, M C Ferraz da; Ribeiro, H B; Kessler, F; Souza, E A T de; Fechine, G J M

    2016-01-01

    In this work, an alternative technique to the traditional micromechanical exfoliation of two-dimensional materials is proposed, consisting of isolated flakes of graphite and molybdenum disulphide onto polymeric surfaces films. The set made up of polymer and flakes is fabricated by using a hot-press machine called polymeric stamp. The polymeric stamp was used to allocate flakes and also to allow the exfoliation process to take place just in one face of isolated flake. Optical microscopy, Raman spectroscopy and photoluminescence spectroscopy results showed that multilayers, bilayers and single layers of graphene and MoS 2 were obtained by using a polymeric stamp as tool for micromechanical exfoliation. These crystals were more easily found because the exfoliation process concentrates them in well-defined locations. The results prove the effectiveness of the method by embedding two-dimensional materials into polymers to fabricate fewer layers crystals in a fast, economic and clean way. (paper)

  5. Micromechanical exfoliation of two-dimensional materials by a polymeric stamp

    Science.gov (United States)

    Ferraz da Costa, M. C.; Ribeiro, H. B.; Kessler, F.; de Souza, E. A. T.; Fechine, G. J. M.

    2016-02-01

    In this work, an alternative technique to the traditional micromechanical exfoliation of two-dimensional materials is proposed, consisting of isolated flakes of graphite and molybdenum disulphide onto polymeric surfaces films. The set made up of polymer and flakes is fabricated by using a hot-press machine called polymeric stamp. The polymeric stamp was used to allocate flakes and also to allow the exfoliation process to take place just in one face of isolated flake. Optical microscopy, Raman spectroscopy and photoluminescence spectroscopy results showed that multilayers, bilayers and single layers of graphene and MoS2 were obtained by using a polymeric stamp as tool for micromechanical exfoliation. These crystals were more easily found because the exfoliation process concentrates them in well-defined locations. The results prove the effectiveness of the method by embedding two-dimensional materials into polymers to fabricate fewer layers crystals in a fast, economic and clean way.

  6. Robust finite-time tracking control for nonlinear suspension systems via disturbance compensation

    Science.gov (United States)

    Pan, Huihui; Jing, Xingjian; Sun, Weichao

    2017-05-01

    This paper focuses on the finite-time tracking control with external disturbance for active suspension systems. In order to compensate unknown disturbance efficiently, a disturbance compensator with finite-time convergence property is studied. By analyzing the discontinuous phenomenon of classical disturbance compensation techniques, this study presents a simple approach to construct a continuous compensator satisfying the finite-time disturbance rejection performance. According to the finite-time separation principle, the design procedures of the nominal controller for the suspension system without disturbance and the disturbance compensator can be implemented in a completely independent manner. Therefore, the overall control law for the closed-loop system is continuous, which offers some distinct advantages over the existing discontinuous ones. From the perspective of practical implementation, the continuous controller can avoid effectively the unexpected chattering in active suspension control. Comparative experimental results are presented and discussed to illustrate the advantage and effectiveness of the proposed control strategy.

  7. Growing Arabidopsis in vitro: cell suspensions, in vitro culture, and regeneration.

    Science.gov (United States)

    Barkla, Bronwyn J; Vera-Estrella, Rosario; Pantoja, Omar

    2014-01-01

    An understanding of basic methods in Arabidopsis tissue culture is beneficial for any laboratory working on this model plant. Tissue culture refers to the aseptic growth of cells, organs, or plants in a controlled environment, in which physical, nutrient, and hormonal conditions can all be easily manipulated and monitored. The methodology facilitates the production of a large number of plants that are genetically identical over a relatively short growth period. Techniques, including callus production, cell suspension cultures, and plant regeneration, are all indispensable tools for the study of cellular biochemical and molecular processes. Plant regeneration is a key technology for successful stable plant transformation, while cell suspension cultures can be exploited for metabolite profiling and mining. In this chapter we report methods for the successful and highly efficient in vitro regeneration of plants and production of stable cell suspension lines from leaf explants of both Arabidopsis thaliana and Arabidopsis halleri.

  8. Imaging the Microscopic Structure of Shear Thinning and Thickening Colloidal Suspensions

    KAUST Repository

    Cheng, X.

    2011-09-01

    The viscosity of colloidal suspensions varies with shear rate, an important effect encountered in many natural and industrial processes. Although this non-Newtonian behavior is believed to arise from the arrangement of suspended particles and their mutual interactions, microscopic particle dynamics are difficult to measure. By combining fast confocal microscopy with simultaneous force measurements, we systematically investigate a suspension\\'s structure as it transitions through regimes of different flow signatures. Our measurements of the microscopic single-particle dynamics show that shear thinning results from the decreased relative contribution of entropic forces and that shear thickening arises from particle clustering induced by hydrodynamic lubrication forces. This combination of techniques illustrates an approach that complements current methods for determining the microscopic origins of non-Newtonian flow behavior in complex fluids.

  9. Performance Testing of Suspension Plasma Sprayed Thermal Barrier Coatings Produced with Varied Suspension Parameters

    Directory of Open Access Journals (Sweden)

    Nicholas Curry

    2015-07-01

    Full Text Available Suspension plasma spraying has become an emerging technology for the production of thermal barrier coatings for the gas turbine industry. Presently, though commercial systems for coating production are available, coatings remain in the development stage. Suitable suspension parameters for coating production remain an outstanding question and the influence of suspension properties on the final coatings is not well known. For this study, a number of suspensions were produced with varied solid loadings, powder size distributions and solvents. Suspensions were sprayed onto superalloy substrates coated with high velocity air fuel (HVAF -sprayed bond coats. Plasma spray parameters were selected to generate columnar structures based on previous experiments and were maintained at constant to discover the influence of the suspension behavior on coating microstructures. Testing of the produced thermal barrier coating (TBC systems has included thermal cyclic fatigue testing and thermal conductivity analysis. Pore size distribution has been characterized by mercury infiltration porosimetry. Results show a strong influence of suspension viscosity and surface tension on the microstructure of the produced coatings.

  10. Production of secondary metabolites trimethyl xanthina by Camellia sinensis L suspension culture

    Science.gov (United States)

    Sutini, Sodiq, Mochamad; Muslihatin, Wirdhatul; Indra, Mochamad Rasjad

    2017-06-01

    Bioactive trimethyl xanthina can be obtained from the plant Camellia sinensis L. To obtain bioactive plant of which there are several hurdles for instance to wait up to five years to be harvested, also it needs land at a certain height from the sea level. Therefore, the production of secondary metabolites trimethyl xanthina need to be developed with suspense culture techniques. The purpose of this study obtained the production of bioactive trimethyl xanthina way culturally suspense in large scale with a relatively short time, potentially as anti-oxidants. Research methods include: (1) initiation of callus from pieces of leaves, shoots the youngest of the plant Camellia sinensis L in the media MS with the optimization of the addition of growth regulators, (2) the subculture of callus on media and plant growth regulator that is equal to the stage of initiation, (3) initiation of suspension culture using explants of callus Camellia sinensis L, (4) Analysis of secondary metabolites trimethyl xanthina growth in suspension culture, (5) the isolation and identification of trimethyl xanthina qualitatively and quantitatively using thin layer chromatography/high performance chromatography column. The results of the study suspension cultures containing bioactive trimethyl xanthina candidates that can be used as an antioxidant.

  11. Suspension Hydrogen Reduction of Iron Oxide Concentrates

    Energy Technology Data Exchange (ETDEWEB)

    H.Y. Sohn

    2008-03-31

    The objective of the project is to develop a new ironmaking technology based on hydrogen and fine iron oxide concentrates in a suspension reduction process. The ultimate objective of the new technology is to replace the blast furnace and to drastically reduce CO2 emissions in the steel industry. The goals of this phase of development are; the performance of detailed material and energy balances, thermochemical and equilibrium calculations for sulfur and phosphorus impurities, the determination of the complete kinetics of hydrogen reduction and bench-scale testing of the suspension reduction process using a large laboratory flash reactor.

  12. Intelligent systems of the vehicles’ suspension

    Science.gov (United States)

    Yurlin, D.

    2018-02-01

    The article is devoted to the current condition of car’s active suspension system. It presents the tendencies in development of the active systems of suspension system, adjustable elements incorporated in them and the companies succeeded in designing such systems. It also mirrors the problem of impact of active systems on car’s safety and their importance for the driver. Advantages and disadvantages of the most common types of active elements are being described, analyzed and compared. The author concludes about the perspectives of these systems’ development.

  13. Unifying Suspension and Granular flows near Jamming

    Directory of Open Access Journals (Sweden)

    DeGiuli Eric

    2017-01-01

    Full Text Available Rheological properties of dense flows of hard particles are singular as one approaches the jamming threshold where flow ceases, both for granular flows dominated by inertia, and for over-damped suspensions. Concomitantly, the lengthscale characterizing velocity correlations appears to diverge at jamming. Here we review a theoretical framework that gives a scaling description of stationary flows of frictionless particles. Our analysis applies both to suspensions and inertial flows of hard particles. We report numerical results in support of the theory, and show the phase diagram that results when friction is added, delineating the regime of validity of the frictionless theory.

  14. Gravity Drainage Kinetics of Papermaking Fibrous Suspensions

    Directory of Open Access Journals (Sweden)

    Przybysz Piotr

    2014-12-01

    Full Text Available The study analyses application possibilities of filtration and thickening models in evaluation of papermaking suspension drainage rate. The authors proposed their own method to estimate the drainage rate on the basis of an existing Ergun capillary model of liquid flow through a granular material. The proposed model was less sensitive to porosity changes than the Ergun model. An empirical verification proved robustness of the proposed approach. Taking into account discrepancies in the published data concerning how the drainage velocity of papermaking suspension is defined, this study examines which of the commonly applied models matches experimental results the best.

  15. Tracer diffusion in colloidal suspensions under dilute and crowded conditions with hydrodynamic interactions

    DEFF Research Database (Denmark)

    Tomilov, A.; Videcoq, A.; Chartier, T.

    2012-01-01

    We consider tracer diffusion in colloidal suspensions under solid loading conditions, where hydrodynamic interactions play an important role. To this end, we carry out computer simulations based on the hybrid stochastic rotation dynamics-molecular dynamics (SRD-MD) technique. Many details of the ...... that hydrodynamic interactions are correctly included within the SRD-MD technique. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4731661]...

  16. Polymeric implant of methylprednisolone for spinal injury ...

    African Journals Online (AJOL)

    Polymeric implant of methylprednisolone for spinal injury: preparation and characterization. Bo Yin, Jian-Jun Ji, Ming Yang. Abstract. Purpose: To improve the effectiveness and reduce the systemic side effects of methylprednisolone in traumatic spinal injuries, its polymeric implants were prepared using chitosan and sodium ...

  17. Development of a falling ball rheometer with applications to opaque systems: measurements of the rheology of suspensions of rods

    International Nuclear Information System (INIS)

    Powell, R.L.; Mondy, L.A.; Stoker, G.G.; Milliken, W.J.; Graham, A.L.

    1989-01-01

    With falling ball rheometry, we have measured the apparent relative viscosity of suspensions of large, neutrally buoyant, rigid rods in a viscous Newtonian fluid, while approximately maintaining the rods in a randomly oriented configuration. A new technique for measuring the time of flight of a ball between two positions is used. This computerized technique, based upon an eddy current detector, enables us to determine the position of a metallic (nonmagnetic) ball falling through an opaque suspension, with high accuracy (less than 1.5% error). The rods for the suspensions had a nominal aspect ratio of 10 and experiments were carried out at a single volume fraction, 0.05. Two populations of rods were used to having nominal diameters of 1.5875 mm and 3.175 mm. To within the errors of these experiments, suspensions from both populations had the same relative viscosity, with the overall average being 1.457. This viscosity was significantly different from that of a similar suspension (volume fraction=0.05) of rods of nominal aspect ratio 20 and it agreed well with theoretical results for the viscosity of a dilute suspension of randomly oriented rods

  18. Metabolic cycles in primary metabolism of cell suspensions of Daucus carota L. analysed by C-NMR

    NARCIS (Netherlands)

    Krook, J.

    1999-01-01

    In the work described in this thesis, uptake and conversion of sugar by cells of batch-grown suspensions of Daucus carota L. were studied. Invasive techniques (measurements of enzyme activities and sugar and starch levels) and non-invasive techniques (

  19. Macrostructure of smectite-water systems. Influence of anionic poly-electrolytes on the organisation of montmorillonite suspensions

    International Nuclear Information System (INIS)

    Morvan, Mikel

    1993-01-01

    In its first part, this research thesis reports a bibliographical study which aimed at highlighting the main aspects of smectite swelling, discusses the organisation of smectite suspension, and briefly presents the knowledge on clay-polymer mixtures. Then, the author describes the method he used to characterise clay suspensions (relaxation, MNR, osmometric techniques, small-angle X-ray diffraction), and theoretical elements required to interpret results. He addresses more particularly the organisation of smectite-water systems with either a natural smectite (montmorillonite) or a synthetic one (laponite) which have different geometries. The last part addresses the interactions between a montmorillonite suspension and sodium polyacrylates. The author, based on the use of small-angle X-ray diffraction and the measurement of the polyelectrolyte osmotic pressure, proposes a new interpretation of the action mechanism of an anionic polyelectrolyte of low molecular mass within a montmorillonite suspension

  20. Spray-dried powders improve the controlled release of antifungal tioconazole-loaded polymeric nanocapsules compared to with lyophilized products

    International Nuclear Information System (INIS)

    Ribeiro, Roseane Fagundes; Motta, Mariana Heldt; Härter, Andréia Pisching Garcia; Flores, Fernanda Cramer; Beck, Ruy Carlos Ruver; Schaffazick, Scheila Rezende

    2016-01-01

    This work aimed to obtain solid formulations from polymeric nanocapsules and nanoemulsions containing tioconazole, a broad spectrum antifungal drug. Two dehydration methods were used: spray-drying and freeze-drying, using lactose as adjuvant (10%, w/v). The liquid formulations had a mean particle size around 206 nm and 182 nm for nanocapsules and nanoemulsions, respectively, and an adequate polydispersity index. Tioconazole content was close to the theoretical amount (1.0 mg/mL). After drying, the content ranged between 98 and 102% with a mean nanometric size of the dried products after redispersion. Scanning electron microscopy showed that the particles are rounded, sphere-shaped for the dried products obtained by spray-drying, and shapeless and irregular shapes for those obtained by freeze-drying. In the microbiological evaluation, all dried products remained active against the yeast Candida albicans when compared to the original systems. The dried products obtained by spray-drying from nanocapsules presented better control of the tioconazole release when compared to the freeze-drying products. - Highlights: • Polymeric nanocapsule suspensions containing tioconazole were submitted to spray-drying and freeze-drying. • Dried products from nanocapsule suspensions were stable for 30 days. • Release studies showed that the dried products presented greater control of drug release compared to the original suspension.

  1. Spray-dried powders improve the controlled release of antifungal tioconazole-loaded polymeric nanocapsules compared to with lyophilized products

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Roseane Fagundes [Programa de Pós-Graduação em Ciências Farmacêuticas, Universidade Federal de Santa Maria, Av. Roraima, 1000, Santa Maria, RS, 97105-900 (Brazil); Motta, Mariana Heldt [Curso de Farmácia, Centro de Ciências da Saúde, Universidade Federal de Santa Maria, Av. Roraima, 1000, Santa Maria, RS, 97105-900 (Brazil); Härter, Andréia Pisching Garcia; Flores, Fernanda Cramer [Programa de Pós-Graduação em Ciências Farmacêuticas, Universidade Federal de Santa Maria, Av. Roraima, 1000, Santa Maria, RS, 97105-900 (Brazil); Beck, Ruy Carlos Ruver [Programa de Pós-Graduação em Ciências Farmacêuticas, Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul, Av. Ipiranga, 2752, Porto Alegre, RS, 90610-000 (Brazil); Schaffazick, Scheila Rezende [Programa de Pós-Graduação em Ciências Farmacêuticas, Universidade Federal de Santa Maria, Av. Roraima, 1000, Santa Maria, RS, 97105-900 (Brazil); and others

    2016-02-01

    This work aimed to obtain solid formulations from polymeric nanocapsules and nanoemulsions containing tioconazole, a broad spectrum antifungal drug. Two dehydration methods were used: spray-drying and freeze-drying, using lactose as adjuvant (10%, w/v). The liquid formulations had a mean particle size around 206 nm and 182 nm for nanocapsules and nanoemulsions, respectively, and an adequate polydispersity index. Tioconazole content was close to the theoretical amount (1.0 mg/mL). After drying, the content ranged between 98 and 102% with a mean nanometric size of the dried products after redispersion. Scanning electron microscopy showed that the particles are rounded, sphere-shaped for the dried products obtained by spray-drying, and shapeless and irregular shapes for those obtained by freeze-drying. In the microbiological evaluation, all dried products remained active against the yeast Candida albicans when compared to the original systems. The dried products obtained by spray-drying from nanocapsules presented better control of the tioconazole release when compared to the freeze-drying products. - Highlights: • Polymeric nanocapsule suspensions containing tioconazole were submitted to spray-drying and freeze-drying. • Dried products from nanocapsule suspensions were stable for 30 days. • Release studies showed that the dried products presented greater control of drug release compared to the original suspension.

  2. A plasma polymerization technique to overcome cerebrospinal fluid shunt infections

    Czech Academy of Sciences Publication Activity Database

    Çökeliler, D.; Caner, H.; Zemek, Josef; Choukourov, A.; Biederman, H.; Mutlu, M.

    2007-01-01

    Roč. 2, č. 1 (2007), s. 39-47 ISSN 1748-6041 Grant - others:TUBITAK(TR) MISAG-COST 527 Institutional research plan: CEZ:AV0Z10100521 Keywords : shunt infections * cerebrospinal * PP HEMA * biomaterials Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.787, year: 2007

  3. Simple technique for characterization of ion-modified polymeric foils

    Czech Academy of Sciences Publication Activity Database

    Vacík, Jiří; Červená, Jarmila; Hnatowicz, Vladimír; Pošta, S.; Fink, D.; Klett, R.; Strauss, P.

    2000-01-01

    Roč. 123, - (2000), s. 97-100 ISSN 0257-8972 R&D Projects: GA ČR GA203/99/1626; GA AV ČR KSK1010601 Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.002, year: 2000

  4. Fluid Effects in Polymers and Polymeric Composites

    CERN Document Server

    Weitsman, Y Jack

    2012-01-01

    Fluid Effects in Polymers and Polymeric Composites, written by the late Dr. Y. Jack Weitsman, addresses the wide range of parameters that affect the interaction of fluids with polymers and polymeric composites. The book aims at broadening the scope of available data, mostly limited up to this time to weight-gain recordings of fluid ingress into polymers and composites, to the practical circumstances of fluctuating exposure. Various forms of experimental data are given, in conjunction with theoretical models derived from basic scientific principles, and correlated with severity of exposure conditions and interpreted by means of rationally based theoretical models. The practical implications of the effects of fluids are discussed. The issue of fluid effects on polymers and polymeric composites is of concern to engineers and scientists active in aerospace and naval structures, as an increasing portion of these structures are made of polymeric composites and employ polymeric adhesives as a joining device. While...

  5. Decoupling Suspension Controller Based on Magnetic Flux Feedback

    Directory of Open Access Journals (Sweden)

    Wenqing Zhang

    2013-01-01

    Full Text Available The suspension module control system model has been established based on MIMO (multiple input and multiple output state feedback linearization. We have completed decoupling between double suspension points, and the new decoupling method has been applied to CMS04 magnetic suspension vehicle in national mid-low-speed maglev experiment field of Tangshan city in China. Double suspension system model is very accurate for investigating stability property of maglev control system. When magnetic flux signal is taken back to the suspension control system, the suspension module’s antijamming capacity for resisting suspension load variety has been proved. Also, the external force interference has been enhanced. As a result, the robustness and stability properties of double-electromagnet suspension control system have been enhanced.

  6. On the Benefits of Semi-Active Suspensions with Inerters

    Directory of Open Access Journals (Sweden)

    Xin-Jie Zhang

    2012-01-01

    Full Text Available Inerters have become a hot topic in recent years especially in vehicle, train, building suspension systems, etc. Eight different layouts of suspensions were analyzed with a quarter-car model in this paper. Dimensionless root mean square (RMS responses of the sprung mass vertical acceleration, the suspension travel, and the tire deflection are derived which were used to evaluate the performance of the quarter-car model. The behaviour of semi-active suspensions with inerters using Groundhook, Skyhook, and Hybrid control has been evaluated and compared to the performance of passive suspensions with inerters. Sensitivity analysis was applied to the development of a high performance semi-active suspension with an inerter. Numerical simulations indicate that a semi-active suspension with an inerter has much better performance than the passive suspension with an inerter, especially with the Hybrid control method, which has the best compromise between comfort and road holding quality.

  7. Decoupling suspension controller based on magnetic flux feedback.

    Science.gov (United States)

    Zhang, Wenqing; Li, Jie; Zhang, Kun; Cui, Peng

    2013-01-01

    The suspension module control system model has been established based on MIMO (multiple input and multiple output) state feedback linearization. We have completed decoupling between double suspension points, and the new decoupling method has been applied to CMS04 magnetic suspension vehicle in national mid-low-speed maglev experiment field of Tangshan city in China. Double suspension system model is very accurate for investigating stability property of maglev control system. When magnetic flux signal is taken back to the suspension control system, the suspension module's antijamming capacity for resisting suspension load variety has been proved. Also, the external force interference has been enhanced. As a result, the robustness and stability properties of double-electromagnet suspension control system have been enhanced.

  8. Measurements on an electromagnetic active suspension system for automotive applications

    NARCIS (Netherlands)

    Gysen, B.L.J.; Paulides, J.J.H.; Lomonova, E.A.; Encica, L.; Gysen, B.L.J.; Jansen, J.W.; Krop, D.C.J.

    2008-01-01

    Abstract—This paper describes the specifications for active suspension systems and provides an electromagnetic solution. Electromagnetic actuation and preliminary control strategies are investigated in order to achieve a suspension system with the ability to absorb road irregularities and perform

  9. Fuzzy logic control of vehicle suspensions with dry friction nonlinearity

    Indian Academy of Sciences (India)

    Fuzzy logic control; active vehicle suspension; suspension space. 1. ... surface unevenness, stability and directional control during handling ..... Burton A W, Truscott A J, Wellstead P E 1995 Analysis, modeling and control of an advanced.

  10. A Novel Seeding Method of Interfacial Polymerization-Assisted Dip Coating for the Preparation of Zeolite NaA Membranes on Ceramic Hollow Fiber Supports.

    Science.gov (United States)

    Cao, Yue; Wang, Ming; Xu, Zhen-Liang; Ma, Xiao-Hua; Xue, Shuang-Mei

    2016-09-28

    A novel seeding method combining interfacial polymerization (IP) technique with dip-coating operation was designed for directly coating nanosized NaA seed crystals (150 nm) onto the micrometer-sized α-Al2O3 hollow fiber support, in which the polyamide (PA) produced by IP acted as an effective medium to freeze and fix seed crystals at the proper position so that the controlled seed layer could be accomplished. While a coating suspension with only 0.5 wt % seed content was used, a very thin seed layer with high quality and good adhesion was achieved through dip coating twice without drying between, and the whole seeding process was operated at ambient conditions. The resulting zeolite NaA membranes not only exhibited high pervaporation (PV) performance with an average separation factor above 10000 and flux nearly 9.0 kg/m(2)·h in dehydration of 90 wt % ethanol aqueous solution at 348 K but also demonstrated great reproducibility by testing more than eight batches of zeolite membranes. In addition, this seeding strategy could be readily extended to the preparation of other supported zeolite membranes for a wide range of separation applications.

  11. Synthesis and Characterization of the in Situ Bulk Polymerization of PMMA Containing Graphene Sheets Using Microwave Irradiation

    Directory of Open Access Journals (Sweden)

    Mohammad A. Aldosari

    2013-03-01

    Full Text Available Polymethylmethacrylate–graphene (PMMA/RGO nanocomposites were prepared via in situ bulk polymerization using two different preparation techniques. In the first approach, a mixture of graphite oxide (GO and methylmethacrylate monomers (MMA were polymerized using a bulk polymerization method with a free radical initiator. After the addition of the reducing agent hydrazine hydrate (HH, the product was reduced via microwave irradiation (MWI to obtain R-(GO-PMMA composites. In the second approach, a mixture of graphite sheets (RGO and MMA monomers were polymerized using a bulk polymerization method with a free radical initiator to obtain RGO-(PMMA composites. The composites were characterized by FTIR, 1H-NMR and Raman spectroscopy and XRD, SEM, TEM, TGA and DSC. The results indicate that the composite obtained using the first approach, which involved MWI, had a better morphology and dispersion with enhanced thermal stability compared with the composites prepared without MWI.

  12. In Situ Monitoring of RAFT Polymerization by Tetraphenylethylene-Containing Agents with Aggregation-Induced Emission Characteristics.

    Science.gov (United States)

    Liu, Shunjie; Cheng, Yanhua; Zhang, Haoke; Qiu, Zijie; Kwok, Ryan T K; Lam, Jacky W Y; Tang, Ben Zhong

    2018-05-22

    A facile and efficient approach is demonstrated to visualize the polymerization in situ. A group of tetraphenylethylene (TPE)-containing dithiocarbamates were synthesized and screened as agents for reversible addition fragmentation chain transfer (RAFT) polymerizations. The spatial-temporal control characteristics of photochemistry enabled the RAFT polymerizations to be ON and OFF on demand under alternating visible light irradiation. The emission of TPE is sensitive to the local viscosity change owing to its aggregation-induced emission characteristic. Quantitative information could be easily acquired by the naked eye without destroying the reaction system. Furthermore, the versatility of such a technique was well demonstrated by 12 different polymerization systems. The present approach thus demonstrated a powerful platform for understanding the controlled living radical polymerization process. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. "Restorative Practices" Offer Alternatives to Suspension

    Science.gov (United States)

    Shah, Nirvi

    2012-01-01

    At City Springs and many other schools across the country, restorative practices are about holding students accountable and getting them to right a wrong. The approach is getting more notice than ever as criticism grows of zero-tolerance disciplinary policies that often require out-of-school suspension and expulsion. Educators are turning to…

  14. Mesoscopic electrohydrodynamic simulations of binary colloidal suspensions

    NARCIS (Netherlands)

    Rivas, Nicolas; Frijters, Stefan; Pagonabarraga, Ignacio; Harting, Jens

    2018-01-01

    A model is presented for the solution of electrokinetic phenomena of colloidal suspensions in fluid mixtures. We solve the discrete Boltzmann equation with a Bhatnagar-Gross-Krook collision operator using the lattice Boltzmann method to simulate binary fluid flows. Solvent-solvent and solvent-solute

  15. 75 FR 68704 - Suspension of Community Eligibility

    Science.gov (United States)

    2010-11-09

    ... DEPARTMENT OF HOMELAND SECURITY Federal Emergency Management Agency 44 CFR Part 64 [Docket ID FEMA-2010-0003; Internal Agency Docket No. FEMA-8155] Suspension of Community Eligibility AGENCY: Federal.... Acadia Parish. Emerg; February 4, 1981, Reg; November 26, 2010, Susp. Iota, Town of, Acadia 220005...

  16. Suspension of Water Droplets on Individual Pillars

    DEFF Research Database (Denmark)

    Tóth, T.; Ferraro, D.; Chiarello, E.

    2011-01-01

    We report results of extensive experimental and numerical studies on the suspension of water drops deposited on cylindrical pillars having circular and square cross sections and different wettabilities. In the case of circular pillars, the drop contact line is pinned to the whole edge contour unt...

  17. ENHANCEMENT OF DURABILITY OF TRACTOR SUSPENSION AXLES

    Directory of Open Access Journals (Sweden)

    I. Doshchechkina

    2017-12-01

    Full Text Available The ‘soft’ nitriding of the suspension axle surface of the T150K tractor at the depth of 0.08 mm enables us to enhance its constructive strength, to increase its service life by 25 % and have a considerable economic effect.

  18. Pair-correlations in swimmer suspensions

    Science.gov (United States)

    Nambiar, Sankalp; Subramanian, Ganesh

    2017-11-01

    Suspensions of rear-actuated swimming microorganisms, such as E.coli, exhibit several interesting phenomena including spontaneous pattern formation above a critical concentration, novel rheological properties, shear-induced concentration banding etc. Explanations based on mean-field theory are only qualitative, since interactions between swimmers are important for typical experimental concentrations. We analytically characterize the hydrodynamic pair-interactions in a quiescent suspension of slender straight swimmers. The pair-correlation, calculated at leading order by integrating the swimmer velocity disturbances along straight trajectories, decays as 1/r2 for r >> L (L being the swimmer size). This allows us to characterize both polar and nematic correlations in an interacting swimmer suspension. In the absence of correlations, the velocity covariance asymptotes from a constant for r > L, the latter being characteristic of a suspension of non-interacting point force-dipoles. On including correlations, the slow decay of the pair-orientation correlation leads to an additional contribution to the velocity covariance that diverges logarithmically with system size.

  19. Baltimore District Tackles High Suspension Rates

    Science.gov (United States)

    Maxwell, Lesli A.

    2007-01-01

    This article reports on how the Baltimore District tackles its high suspension rates. Driven by an increasing belief that zero-tolerance disciplinary policies are ineffective, more educators are embracing strategies that do not exclude misbehaving students from school for offenses such as insubordination, disrespect, cutting class, tardiness, and…

  20. Absorption Spectra of Gold Nanoparticle Suspensions

    Science.gov (United States)

    Anan'eva, M. V.; Nurmukhametov, D. R.; Zverev, A. S.; Nelyubina, N. V.; Zvekov, A. A.; Russakov, D. M.; Kalenskii, A. V.; Eremenko, A. N.

    2018-02-01

    Three gold nanoparticle suspensions are obtained, and mean radii in distributions - (6.1 ± 0.2), (11.9 ± 0.3), and (17.3 ± 0.7) nm - are determined by the transmission electron microscopy method. The optical absorption spectra of suspensions are obtained and studied. Calculation of spectral dependences of the absorption index of suspensions at values of the gold complex refractive index taken from the literature showed a significant deviation of experimental and calculated data in the region of 450-800 nm. Spectral dependences of the absorption of suspensions are simulated within the framework of the Mie-Drude theory taking into account the interband absorption in the form of an additional term in the imaginary part of the dielectric permittivity of the Gaussian type. It is shown that to quantify the spectral dependences in the region of the plasmon absorption band of nanoparticles, correction of the parameters of the interband absorption is necessary in addition to the increase of the relaxation parameter of the Drude theory. Spectral dependences of the dielectric permittivity of gold in nanodimensional state are refined from the solution of the inverse problem. The results of the present work are important for predicting the special features of operation of photonic devices and optical detonators based on gold nanoparticles.

  1. Alternatives to School Disciplinary and Suspension Problems.

    Science.gov (United States)

    South Carolina State Dept. of Education, Columbia. Div. of Instruction.

    Policies and procedures for disciplining students should be designed to teach them responsibility, rather than simply punish them. Providing educational opportunities to behavioral deviants is a problem that does not have a simple solution. However, alternatives to suspension or expulsion must be attempted before these disciplinary actions are…

  2. Electrorheological suspensions of laponite in oil: rheometry studies.

    Science.gov (United States)

    Parmar, K P S; Méheust, Y; Schjelderupsen, Børge; Fossum, J O

    2008-03-04

    We have studied the effect of an external direct current (DC) electric field ( approximately 1 kV/mm) on the rheological properties of colloidal suspensions consisting of aggregates of laponite particles in a silicone oil. Microscopy observations show that, under application of an electric field greater than a triggering electric field Ec approximately 0.6 kV/mm, laponite aggregates assemble into chain- and/or columnlike structures in the oil. Without an applied electric field, the steady-state shear behavior of such suspensions is Newtonian-like. Under application of an electric field larger than Ec, it changes dramatically as a result of the changes in the microstructure: a significant yield stress is measured, and under continuous shear the fluid is shear-thinning. The rheological properties, in particular the dynamic and static shear stress, were studied as a function of particle volume fraction for various strengths (including null) of the applied electric field. The flow curves at constant shear rate can be scaled with respect to both the particle fraction and electric field strength onto a master curve. This scaling is consistent with simple scaling arguments. The shape of the master curve accounts for the system's complexity; it approaches a standard power-law model at high Mason numbers. Both dynamic and static yield stresses are observed to depend on the particle fraction Phi and electric field E as PhibetaEalpha, with alpha approximately 1.85 and beta approximately 1 and 1.70 for the dynamic and static yield stresses, respectively. The yield stress was also determined as the critical stress at which there occurs a bifurcation in the rheological behavior of suspensions that are submitted to a constant shear stress; a scaling law with alpha approximately 1.84 and beta approximately 1.70 was obtained. The effectiveness of the latter technique confirms that such electrorheological (ER) fluids can be studied in the framework of thixotropic fluids. The method

  3. Modeling liquid crystal polymeric devices

    Science.gov (United States)

    Gimenez Pinto, Vianney Karina

    The main focus of this work is the theoretical and numerical study of materials that combine liquid crystal and polymer. Liquid crystal elastomers are polymeric materials that exhibit both the ordered properties of the liquid crystals and the elastic properties of rubbers. Changing the order of the liquid crystal molecules within the polymer network can induce shape change. These materials are very valuable for applications such as actuators, sensors, artificial muscles, haptic displays, etc. In this work we apply finite element elastodynamics simulations to study the temperature induced shape deformation in nematic elastomers with complex director microstructure. In another topic, we propose a novel numerical method to model the director dynamics and microstructural evolution of three dimensional nematic and cholesteric liquid crystals. Numerical studies presented in this work are in agreement with experimental observations and provide insight into the design of application devices.

  4. Polymerization of lanthanide acrylonitrile complexes.

    Science.gov (United States)

    el-Mossalamy, El-Sayed H; Khalil, Ahmed A

    2002-01-01

    The molecular complexes of some lanthanides scandium (Sc3+), yttrium (Y3+), lanthanum (La3+), gadolinium (Gd3+), cerium (Ce3+) and ytterbium (Yb3) have been studies in dimethyl formamide (DMF) spectrophtometrically equilibrium constants (K), molar extintion coefficient (epsilon), energy of transition (E) and free energy (delta G*) were calculated. The polymerization of acrylonitrile has been studied and investigated in the presence of Sc3+, Y3+, La3+, Gd3+, Ce3+, and Yb3+ ions. The IR spectra of the formed AN-M (III) Br3 polymer complexes show the absence of the C identical to N band and the presence of two new bands corresponding to NH2 and OH groups. Magnetic moment values and the thermal stabilities of homopolymer and the polymer complexes were studied by means of thermogravimetric analysis and the activation energies for degradation were calculated.

  5. Electrostratic stabilization of suspensions in non-aqueous media

    NARCIS (Netherlands)

    Hoeven, van der P.C.

    1991-01-01

    Concentrated suspensions of detergent powder solids in a liquid nonionic surfactant are considered for practical application as liquid detergent products. If no precautions are taken, upon storage the viscosity of such suspensions increases and the pourability drops because the suspensions are

  6. Preview based control of suspension systems for commercial vehicles

    NARCIS (Netherlands)

    Muijderman, J.H.E.A.; Kok, J.J.; Huisman, R.G.M.; Veldpaus, F.E.; van Heck, J.G.A.M.

    1999-01-01

    An active suspension with preview is developed for the rear axle of a commercial vehicle. The obtained improvements are promising and justify further investigation of the more feasible semi-active suspensions with preview. The inherent non-linearity of semi-active suspensions with switching shock

  7. Professor Jesse W. Beams and the first practical magnetic suspension

    Science.gov (United States)

    Allaire, P. E.; Humphris, R. R.; Lewis, D. W.

    1992-01-01

    Dr. Jesse W. Beams developed the first practical magnetic suspension for high speed rotating devices. The devices included high speed rotating mirrors, ultracentrifuges, and high speed centrifugal field rotors. A brief biography of Dr. Beams is presented, and the following topics are discussed: (1) early axial magnetic suspension for ultracentrifuges; and (2) magnetic suspension for high centrifugal fields.

  8. Fuzzy logic control of vehicle suspensions with dry friction nonlinearity

    Indian Academy of Sciences (India)

    We design and investigate the performance of fuzzy logic-controlled (FLC) active suspensions on a nonlinear vehicle model with four degrees of freedom, without causing any degeneration in suspension working limits. Force actuators were mounted parallel to the suspensions. In this new approach, linear combinations of ...

  9. Behaviour of humic-bentonite aggregates in diluted suspensions ...

    African Journals Online (AJOL)

    Formation and disaggregation of micron-size aggregates in a diluted suspension made up of HSs and bentonite (B) were studied by tracing distribution of aggregate sizes and their counts in freshly prepared and aged suspensions, and at high (10 000) and low (1.0) [HS]/[B] ratios. Diluted HSB suspensions are unstable ...

  10. 15 CFR 2011.207 - Suspension of the certificate system.

    Science.gov (United States)

    2010-01-01

    ..., SYRUPS AND MOLASSES Specialty Sugar § 2011.207 Suspension of the certificate system. (a) Suspension. The.... Notice of such suspension and the effective date thereof shall be published in the Federal Register. (b... such reinstatement and the effective date thereof shall be published in the Federal Register. (c...

  11. 13 CFR 120.660 - Suspension or revocation.

    Science.gov (United States)

    2010-01-01

    ... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Suspension or revocation. 120.660 Section 120.660 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION BUSINESS LOANS Secondary Market Suspension Or Revocation of Participant in Secondary Market § 120.660 Suspension or revocation. (a...

  12. 39 CFR 3001.114 - Suspension pending review.

    Science.gov (United States)

    2010-07-01

    ... 39 Postal Service 1 2010-07-01 2010-07-01 false Suspension pending review. 3001.114 Section 3001... Suspension pending review. (a) Application. Application for suspension of a determination of the Postal Service to close or consolidate any post office pending the outcome of an appeal to the Postal Regulatory...

  13. 21 CFR 520.905a - Fenbendazole suspension.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Fenbendazole suspension. 520.905a Section 520.905a... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.905a Fenbendazole suspension. (a) Specifications. Each milliliter of suspension contains 100 milligrams (mg) fenbendazole. (b...

  14. Polymeric materials from renewable resources

    Energy Technology Data Exchange (ETDEWEB)

    Frollini, Elisabete; Rodrigues, Bruno V. M.; Silva, Cristina G. da; Castro, Daniele O.; Ramires, Elaine C.; Oliveira, Fernando de; Santos, Rachel P. O. [Macromolecular Materials and Lignocellulosic Fibers Group, Center for Research on Science and Technology of BioResources, Institute of Chemistry of São Carlos, University of São Paulo, CP 780, 13560-970 São Carlos, São Paulo (Brazil)

    2016-05-18

    The goals of our studies have been the use of renewable raw materials in the preparation of polymeric materials with diversified properties. In this context, lignosulfonate, which is produced in large scale around the world, but not widely used in the production of polymeric materials, was used to replace phenol and polyols in the preparation of phenolic- (Ligno-PH) and polyurethane-type (Ligno-PU) polymers, respectively. These polymers were used to prepare composites reinforced with sisal lignocellulosic fibers. The use of lignosulfonate in the formulation of both types of polymers was beneficial, because in general composites with improved properties, specially impact strength, were obtained. Composites were also prepared from the so called “biopolyethylene” (HDPE), curaua lignocellulosic fiber, and castor oil (CO). All composites HDBPE/CO/Fiber exhibited higher impact strength, when compared to those of the corresponding HDBPE/Fiber. These results, combined with others (eg SEM images of the fractured surfaces) indicated that, in addition to acting as a plasticizer, this oil may have acted as a compatibilizer of the hydrophilic fiber with the hydrophobic polymer. The set of results indicated that (i) mats with nano (diameter ≤ 100nm) and/or ultrafine (submicron scale) fibers were produced, (ii) hybrid fibers were produced (bio-based mats composites), (iii) cellulosic pulp (CP) and/or lignin (Lig) can be combined with PET matrices to control properties such as stiffness and hydrophilicity of the respective mats. Materials with diversified properties were prepared from high content of renewable raw materials, thus fulfilling the proposed targets.

  15. Polymeric materials from renewable resources

    Science.gov (United States)

    Frollini, Elisabete; Rodrigues, Bruno V. M.; da Silva, Cristina G.; Castro, Daniele O.; Ramires, Elaine C.; de Oliveira, Fernando; Santos, Rachel P. O.

    2016-05-01

    The goals of our studies have been the use of renewable raw materials in the preparation of polymeric materials with diversified properties. In this context, lignosulfonate, which is produced in large scale around the world, but not widely used in the production of polymeric materials, was used to replace phenol and polyols in the preparation of phenolic- (Ligno-PH) and polyurethane-type (Ligno-PU) polymers, respectively. These polymers were used to prepare composites reinforced with sisal lignocellulosic fibers. The use of lignosulfonate in the formulation of both types of polymers was beneficial, because in general composites with improved properties, specially impact strength, were obtained. Composites were also prepared from the so called "biopolyethylene" (HDPE), curaua lignocellulosic fiber, and castor oil (CO). All composites HDBPE/CO/Fiber exhibited higher impact strength, when compared to those of the corresponding HDBPE/Fiber. These results, combined with others (eg SEM images of the fractured surfaces) indicated that, in addition to acting as a plasticizer, this oil may have acted as a compatibilizer of the hydrophilic fiber with the hydrophobic polymer. The set of results indicated that (i) mats with nano (diameter ≤ 100nm) and/or ultrafine (submicron scale) fibers were produced, (ii) hybrid fibers were produced (bio-based mats composites), (iii) cellulosic pulp (CP) and/or lignin (Lig) can be combined with PET matrices to control properties such as stiffness and hydrophilicity of the respective mats. Materials with diversified properties were prepared from high content of renewable raw materials, thus fulfilling the proposed targets.

  16. Functionalization of nanochannels by radio-induced grafting polymerization on PET track-etched membranes

    International Nuclear Information System (INIS)

    Soto Espinoza, S.L.; Arbeitman, C.R.; Clochard, M.C.; Grasselli, M.

    2014-01-01

    The application of swift-heavy ion bombardment to polymers is a well-established technique to manufacture micro- and nanopores onto polymeric films to obtain porous membranes. A few years ago, it was realized that, during ion bombardment, the high energy deposition along the ion path through the polymer reached cylindrical damage regions corresponding to the core trace and the penumbra. After the etching procedure, there are still enough active sites left in the penumbra that can be used to initiate a polymerization process selectively inside the membrane pores. In this study, we report the grafting polymerization of glycidyl methacrylate onto etched PET foils to obtain functionalized nanochannels. Grafted polymers were labeled with a fluorescent tag and analyzed by different fluorescence techniques such as direct fluorescence, fluorescence microscopy and confocal microscopy. These techniques allowed identifying and quantifying the grafted regions on the polymeric foils. - Highlights: • Irradiated PET foils with swift-heavy ions were etched and grafted in a step-by-step process. • Grafting polymerization was performed on the remaining active sites after etching. • Track-etched PET membranes were fluorescently labeled by chemical functionalization. • Functionalized track-etched PET membranes were analyzed by fluorescence and confocal microscopy

  17. Compounding rifampin suspensions with improved injectability for nasogastric enteral feeding tube administration.

    Science.gov (United States)

    de Villiers, Melgardt M; Vogel, Laura; Bogenschutz, Monica C; Fingerhut, Bonnie J; D'Silva, Joseph B; Moore, Anne

    2010-01-01

    Often medications that have to be administered to patients via a nasogastric enteral feeding tubes are only available as tablets and capsules with no suitable commercial liquid alternatives. In such situations, pharmacists and nurses have to compound the tablets and capsule contents into liquid suspension formulations for dosing. The risk of occlusion of the enteral tubes during administration is reduced by employing liquid suspensions that are composed of small and uniform particles, not subject to rapid rates of settling, resistant to caking, and easily and uniformly re-suspended upon agitation. Present techniques often employ a manual process, such as a mortar and pestle, to accomplish the particle size reduction and subsequent incorporation into a suitable liquid diluent. A new compounding device has been invented that employs an automated wet-milling process in a single-use disposable plastic container to compound the suspensions. The two processes were compared using Rifampin capsules and various liquid diluents. A prototype version of the new device was employed in the experiments. The physical characteristics of the compounded suspensions were evaluated by determining sedimentation rate, sedimentation volume, and particle size and shape using laser light scattering, optical microscopy, and scanning electron microscopy techniques. The use characteristic of the compounded suspensions was evaluated using a nasogastric tube inject ability test. The results indicated that suspensions prepared using the new device were more resistant to sedimentation and caking and were easier to re-disperse into a uniform mixture by gentle shaking. The results were a consequence of the particles generated by the new device which were found to be smaller and more uniform in shape and size. The suspensions prepared using the new device did not cause blockage of the enteral feeding tubes in comparison to those prepared using a mortar and pastle. In conclusion, the results indicate

  18. Controlled Bioactive Molecules Delivery Strategies for Tendon and Ligament Tissue Engineering using Polymeric Nanofibers.

    Science.gov (United States)

    Hiong Teh, Thomas Kok; Hong Goh, James Cho; Toh, Siew Lok

    2015-01-01

    The interest in polymeric nanofibers has escalated over the past decade given its promise as tissue engineering scaffolds that can mimic the nanoscale structure of the native extracellular matrix. With functionalization of the polymeric nanofibers using bioactive molecules, localized signaling moieties can be established for the attached cells, to stimulate desired biological effects and direct cellular or tissue response. The inherently high surface area per unit mass of polymeric nanofibers can enhance cell adhesion, bioactive molecules loading and release efficiencies, and mass transfer properties. In this review article, the application of polymeric nanofibers for controlled bioactive molecules delivery will be discussed, with a focus on tendon and ligament tissue engineering. Various polymeric materials of different mechanical and degradation properties will be presented along with the nanofiber fabrication techniques explored. The bioactive molecules of interest for tendon and ligament tissue engineering, including growth factors and small molecules, will also be reviewed and compared in terms of their nanofiber incorporation strategies and release profiles. This article will also highlight and compare various innovative strategies to control the release of bioactive molecules spatiotemporally and explore an emerging tissue engineering strategy involving controlled multiple bioactive molecules sequential release. Finally, the review article concludes with challenges and future trends in the innovation and development of bioactive molecules delivery using polymeric nanofibers for tendon and ligament tissue engineering.

  19. Production methodologies of polymeric and hydrogel particles for drug delivery applications.

    Science.gov (United States)

    Lima, Ana Catarina; Sher, Praveen; Mano, João F

    2012-02-01

    Polymeric particles are ideal vehicles for controlled delivery applications due to their ability to encapsulate a variety of substances, namely low- and high-molecular mass therapeutics, antigens or DNA. Micro and nano scale spherical materials have been developed as carriers for therapies, using appropriated methodologies, in order to achieve a prolonged and controlled drug administration. This paper reviews the methodologies used for the production of polymeric micro/nanoparticles. Emulsions, phase separation, spray drying, ionic gelation, polyelectrolyte complexation and supercritical fluids precipitation are all widely used processes for polymeric micro/nanoencapsulation. This paper also discusses the recent developments and patents reported in this field. Other less conventional methodologies are also described, such as the use of superhydrophobic substrates to produce hydrogel and polymeric particulate biomaterials. Polymeric drug delivery systems have gained increased importance due to the need for improving the efficiency and versatility of existing therapies. This allows the development of innovative concepts that could create more efficient systems, which in turn may address many healthcare needs worldwide. The existing methods to produce polymeric release systems have some critical drawbacks, which compromise the efficiency of these techniques. Improvements and development of new methodologies could be achieved by using multidisciplinary approaches and tools taken from other subjects, including nanotechnologies, biomimetics, tissue engineering, polymer science or microfluidics.

  20. Exploring release and recovery of nanomaterials from commercial polymeric nanocomposites

    International Nuclear Information System (INIS)

    Busquets-Fité, Martí; Puntes, Víctor; Fernandez, Elisabet; Janer, Gemma; Vilar, Gemma; Vázquez-Campos, Socorro; Zanasca, R; Citterio, C; Mercante, L

    2013-01-01

    Much concern has been raised about the risks associated with the broad use of polymers containing nanomaterials. Much is known about degradation and aging of polymers and nanomaterials independently, but very few studies have been done in order to understand degradation of polymeric nanocomposites containing nanomaterials and the fate of these nanomaterials, which may occur in suffering many processes such as migration, release and physicochemical modifications. Throughout the UE funded FP7 project NANOPOLYTOX, studies on the migration, release and alteration of mechanical properties of commercial nanocomposites due to ageing and weathering have been performed along with studies on the feasibility of recovery and recycling of the nanomaterials. The project includes the use as model nanocomposites of Polyamide-6 (PA), Polypropylene (PP) and Ethyl Vinyl Acetate (EVA) as polymeric matrix filled with a 3% in mass of a set of selected broadly used nanomaterials; from inorganic metal oxides nanoparticles (SiO2, TiO2 and ZnO) to multi-walled carbon nanotubes (MWCNT) and Nanoclays. These model nanocomposites were then treated under accelerated ageing conditions in climatic chamber. To determine the degree of degradation of the whole nanocomposite and possible processes of migration, release and modification of the nanofillers, nanocomposites were characterized by different techniques. Additionally, recovery of the nanomaterials fro m the polymeric matrix was addressed, being successfully achieved for PA and PP based nanocomposites. In the case of PA, dissolution of the polymeric matrix using formic acid and further centrifugation steps was the chosen approach, while for PP based nanocomposites calcination was performed.

  1. Microstructural Dynamics and Rheology of Suspensions of Rigid Fibers

    Science.gov (United States)

    Butler, Jason E.; Snook, Braden

    2018-01-01

    The dynamics and rheology of suspensions of rigid, non-Brownian fibers in Newtonian fluids are reviewed. Experiments, theories, and computer simulations are considered, with an emphasis on suspensions at semidilute and concentrated conditions. In these suspensions, interactions between the particles strongly influence the microstructure and rheological properties of the suspension. The interactions can arise from hydrodynamic disturbances, giving multibody interactions at long ranges and pairwise lubrication forces over short distances. For concentrated suspensions, additional interactions due to excluded volume (contacts) and adhesive forces are addressed. The relative importance of the various interactions as a function of fiber concentration is assessed.

  2. Method for forming polymerized microfluidic devices

    Science.gov (United States)

    Sommer, Gregory J.; Hatch, Anson V.; Wang, Ying-Chih; Singh, Anup K.; Renzi, Ronald F.; Claudnic, Mark R.

    2013-03-12

    Methods for making a microfluidic device according to embodiments of the present invention include defining.about.cavity. Polymer precursor solution is positioned in the cavity, and exposed to light to begin the polymerization process and define a microchannel. In some embodiments, after the polymerization process is partially complete, a solvent rinse is performed, or fresh polymer precursor introduced into the microchannel. This may promote removal of unpolymerized material from the microchannel and enable smaller feature sizes. The polymer precursor solution may contain an iniferter. Polymerized features therefore may be capped with the iniferter, which is photoactive. The iniferter may aid later binding of a polyacrylamide gel to the microchannel surface.

  3. AZIDE-ALKYNE CLICK POLYMERIZATION: AN UPDATE

    Institute of Scientific and Technical Information of China (English)

    Hong-kun Li; Jing-zhi Sun; An-jun Qin; Ben Zhong Tang

    2012-01-01

    The great achievements of click chemistry have encouraged polymer scientists to use this reaction in their field.This review assembles an update of the advances of using azide-alkyne click polymerization to prepare functional polytriazoles (PTAs) with linear and hyperbranched structures.The Cu(Ⅰ)-mediated click polymerization furnishes 1,4-regioregular PTAs,whereas,the metal-free click polymerization of propiolates and azides produces PTAs with 1,4-regioisomer contents up to 90%.The PTAs display advanced functions,such as aggregation-induced emission,thermal stability,biocompatibility and optical nonlinearity.

  4. Hydroxyapatite induces spontaneous polymerization of model self-etch dental adhesives.

    Science.gov (United States)

    Zhang, Ying; Wu, Ningjing; Bai, Xinyan; Xu, Changqi; Liu, Yi; Wang, Yong

    2013-10-01

    The objective of this study is to report for the first time the spontaneous polymerization phenomenon of self-etch dental adhesives induced by hydroxylapatite (HAp). Model self-etch adhesives were prepared by using a monomer mixture of bis[2-(methacryloyloxy)ethyl] phosphate (2MP) with 2-hydroxyethyl methacrylate (HEMA). The initiator system consisted of camphorquinone (CQ, 0.022 mmol/g) and ethyl 4-dimethylaminobenzoate (4E, 0.022-0.088 mmol/g). HAp (2-8 wt.%) was added to the neat model adhesive. In a dark environment, the polymerization was monitored in-situ using ATR/FT-IR, and the mechanical properties of the polymerized adhesives were evaluated using nanoindentation technique. Results indicated that spontaneous polymerization was not observed in the absence of HAp. However, as different amounts of HAp were incorporated into the adhesives, spontaneous polymerization was induced. Higher HAp content led to higher degree of conversion (DC), higher rate of polymerization (RP) and shorter induction period (IP). In addition, higher 4E content also elevated DC and RP and reduced IP of the adhesives. Nanoindentation result suggested that the Young's modulus of the polymerized adhesives showed similar dependence on HAp and 4E contents. In summary, interaction with HAp could induce spontaneous polymerization of the model self-etch adhesives. This result provides important information for understanding the initiation mechanism of the self-etch adhesives, and may be of clinical significance to strengthen the adhesive/dentin interface based on the finding. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. High performance nature of biodegradable polymeric nanocomposites for oil-well drilling fluids

    Directory of Open Access Journals (Sweden)

    Tarek M. Madkour

    2016-06-01

    Full Text Available Multi-walled carbon nanotube (MWCNT and graphene nanoplatelet reinforced thermoplastic poly(lactic acid (PLA biodegradable nanocomposites were designed and prepared using solution casting techniques. The prepared biodegradable polymers are expected to provide an environmentally friendly alternative to petroleum-based polymers. Both nanocomposite systems exhibited better thermal stability and improved mechanical performance over the unreinforced polymer exhibiting excellent strength and degradability. The addition of graphene nanofiller in varied amounts was aimed to enhance the thermal and mechanical properties of the nanocomposites even further and incorporate the outstanding characteristics of graphene nanoplatelets into the nanocomposites. The polymeric nanocomposites showed also superior advantages for oil drilling relevances, automotive lubricating purposes, membrane technology and food packaging. Scanning electron microscopy images indicated a homogeneous dispersion of the nanofiller within the polymeric matrix at low filler loadings and a cluster formation at higher loadings that could be responsible for the polymeric matrix movement restrictions. The enthalpy of mixing (the polymer and the nanofiller measured could explain the cause of the repulsive interactions between the nanoparticles and the polymeric chains, which created an additional excluded volume that the polymeric segments were restricted to occupy, thus forcing the conformational characteristics of the polymeric chains to deviate away from those of the bulk chains. The prepared polymeric nano composites (poly lactic acid carbon nano tube and poly lactic acid graphene nanoplatelets were utilized in the formulation of oil-base mud as a viscosifier. The rheological, filtration properties and electrical stability of the oil based mud formulation with the new polymeric nanocomposite were studied and the result compared to the oil-based mud formulation with commercial viscosifier.

  6. NMR relaxation dispersion of Miglyol molecules confined inside polymeric micro-capsules.

    Science.gov (United States)

    Nechifor, Ruben; Ardelean, Ioan; Mattea, Carlos; Stapf, Siegfried; Bogdan, Mircea

    2011-11-01

    Frequency dependent NMR relaxation studies have been carried out on Miglyol molecules confined inside core shell polymeric capsules to obtain a correlation between capsule dimension and the measurable parameters. The polymeric capsules were prepared using an interfacial polymerization technique for three different concentrations of Miglyol. It was shown that the variation of Miglyol concentration influences the capsule dimension. Their average size was estimated using the pulsed field gradient diffusometry technique. The relaxation dispersion curves were obtained at room temperature by a combined use of a fast field cycling instrument and a high-field instrument. The frequency dependence of relaxation rate shows a transition from a diffusion-limited to a surface-limited relaxation regime. Copyright © 2011 John Wiley & Sons, Ltd.

  7. Study on kinematic and compliance test of suspension

    Science.gov (United States)

    Jing, Lixin; Wu, Liguang; Li, Xuepeng; Zhang, Yu

    2017-09-01

    Chassis performance development is a major difficulty in vehicle research and development, which is the main factor restricting the independent development of vehicles in China. These years, through a large number of studies, chassis engineers have found that the suspension K&C characteristics as a quasi-static characteristic of the suspension provides a technical route for the suspension performance R&D, and the suspension K&C test has become an important means of vehicle benchmarking, optimization and verification. However, the research on suspension K&C test is less in china, and the test conditions and setting requirements vary greatly from OEM to OEM. In this paper, the influence of different settings on the characteristics of the suspension is obtained through experiments, and the causes of the differences are analyzed; in order to fully reflect the suspension characteristics, the author recommends the appropriate test case and settings.

  8. Nonlinear Predictive Sliding Mode Control for Active Suspension System

    Directory of Open Access Journals (Sweden)

    Dazhuang Wang

    2018-01-01

    Full Text Available An active suspension system is important in meeting the requirements of the ride comfort and handling stability for vehicles. In this work, a nonlinear model of active suspension system and a corresponding nonlinear robust predictive sliding mode control are established for the control problem of active suspension. Firstly, a seven-degree-of-freedom active suspension model is established considering the nonlinear effects of springs and dampers; and secondly, the dynamic model is expanded in the time domain, and the corresponding predictive sliding mode control is established. The uncertainties in the controller are approximated by the fuzzy logic system, and the adaptive controller reduces the approximation error to increase the robustness of the control system. Finally, the simulation results show that the ride comfort and handling stability performance of the active suspension system is better than that of the passive suspension system and the Skyhook active suspension. Thus, the system can obviously improve the shock absorption performance of vehicles.

  9. In situ characterization of organo-modified and unmodified montmorillonite aqueous suspensions by UV-visible spectroscopy.

    Science.gov (United States)

    Alin, Jonas; Rubino, Maria; Auras, Rafael

    2015-10-15

    UV-visible (UV-Vis) spectroscopy (Tyndall spectra) was applied and tested for its ability to measure organo-modified and unmodified montmorillonite (MMT) clays in aqueous suspensions. A full factorial design of experiments was used to study the influence of pH, NaCl and clay concentrations on the average particle size of the clay agglomerates. The methodology was evaluated by observing results that were consistent with previous research about the unmodified clay's behavior in aqueous suspensions. The results from this evaluation corresponded to accepted theories about the unmodified clay's behavior, indicating that the methodology is precise enough to distinguish the effects of the studied factors on these clay suspensions. The effect of clay concentration was related to the amount of ions per clay particle for the unmodified clay, but was not significant for the organo-modified MMT. The average particle size of the organo-modified MMT in suspension was significantly larger than that of the unmodified clay. Size of the organo-modified MMT agglomerates in suspension decreased in the presence of NaCl and at both high and low pH; this behavior was opposite to that of the unmodified clay. These results demonstrate that the UV-Vis methodology is well-suited for characterizing clay particle size in aqueous suspensions. The technique also is simple, rapid, and low-cost. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Photo and radiation chemistry of polymeric systems and nanomaterials

    International Nuclear Information System (INIS)

    Mikhaylov, A.I.

    2004-01-01

    New approaches of analytical ESR-spectroscopy to studying of free-radical and electron-transport processes at radiation-chemical and photochemical modification both fictionalization of polymeric systems and nanomaterials were surveyed. Measuring techniques using of ESR-spectroscopy of paramagnetic centers were fulfilled. The radiation-chemical processes of modification, microencapsulation and kinetic stabilization of thermodynamically incompatible systems and interfaces for nanomaterials including fullerenes, nanotubes, nanofibres, etc. and composites on the basis of synthetic and natural polymers including plant fibers, fluoropolymers, polyolefins, etc. were developed

  11. Visible Light-Induced Metal Free Surface Initiated Atom Transfer Radical Polymerization of Methyl Methacrylate on SBA-15

    Directory of Open Access Journals (Sweden)

    Liang Ma

    2017-02-01

    Full Text Available Surface-initiated atom transfer radical polymerization (SI-ATRP is one of the most versatile techniques to modify the surface properties of materials. Recent developed metal-free SI-ATRP makes such techniques more widely applicable. Herein photo-induced metal-free SI-ATRP of methacrylates, such as methyl methacrylate, N-isopropanyl acrylamide, and N,N-dimethylaminoethyl methacrylate, on the surface of SBA-15 was reported to fabricate organic-inorganic hybrid materials. A SBA-15-based polymeric composite with an adjustable graft ratio was obtained. The structure evolution during the SI-ATRP modification of SBA-15 was monitored and verified by FT-IR, XPS, TGA, BET, and TEM. The obtained polymeric composite showed enhanced adsorption ability for the model compound toluene in aqueous conditions. This procedure provides a low-cost, readily available, and easy modification method to synthesize polymeric composites without the contamination of metal.

  12. Time varying behaviour of the loudspeaker suspension

    DEFF Research Database (Denmark)

    Agerkvist, Finn; Pedersen, Bo Rohde

    2009-01-01

    The compliance of the loudspeaker suspension is known to depend on the recent excitation level history. Previous investigations have shown that the electrical power as well as displacement and velocity plays a role. In this paper the hypothesis that the changes in compliance are caused mainly...... by how much the suspension has been stretched, i.e., the maximum displacement, is investigated. For this purpose the changes in compliance are measured when exposing the loudspeaker to different levels and types of electrical excitation signals, as well as mechanical excitation only. For sinusoidal...... excitation the change in compliance is shown to depend primarily on maximum displacement. But for square pulse excitation the duration of the excitation also plays an important role....

  13. Mesoscopic electrohydrodynamic simulations of binary colloidal suspensions

    Science.gov (United States)

    Rivas, Nicolas; Frijters, Stefan; Pagonabarraga, Ignacio; Harting, Jens

    2018-04-01

    A model is presented for the solution of electrokinetic phenomena of colloidal suspensions in fluid mixtures. We solve the discrete Boltzmann equation with a Bhatnagar-Gross-Krook collision operator using the lattice Boltzmann method to simulate binary fluid flows. Solvent-solvent and solvent-solute interactions are implemented using a pseudopotential model. The Nernst-Planck equation, describing the kinetics of dissolved ion species, is solved using a finite difference discretization based on the link-flux method. The colloids are resolved on the lattice and coupled to the hydrodynamics and electrokinetics through appropriate boundary conditions. We present the first full integration of these three elements. The model is validated by comparing with known analytic solutions of ionic distributions at fluid interfaces, dielectric droplet deformations, and the electrophoretic mobility of colloidal suspensions. Its possibilities are explored by considering various physical systems, such as breakup of charged and neutral droplets and colloidal dynamics at either planar or spherical fluid interfaces.

  14. Submerged cutting characteristics of abrasive suspension jet

    International Nuclear Information System (INIS)

    Shimizu, Seiji; Peng, Guoyi; Oguma, Yasuyuki; Nishikata, Hiroyuki

    2015-01-01

    An abrasive suspension jet (ASJ) formed by propelling abrasive suspension through a nozzle has a greater cutting capability than the conventional abrasive water jet. However the cutting capability of submerged ASJs decreases drastically with increasing the standoff distance and the pressure around the jet. A sheathed nozzle with ventilation for ASJs has been developed as a mean of extending the effective stand-off distance and improving the cutting capabilities under submerged condition. In the present investigation, cutting tests by ASJs in air and under submerged condition are conducted with specimens of aluminum alloy. Air coated ASJs are formed by using a sheathed nozzle with ventilation. The relative cutting depth is defined as the cutting depth under submerged condition divided by the cutting depth in air at the same standoff distance. The relative cutting depth is arranged effectually by the cavitation number based on the cavity pressure measured at the sheath. (author)

  15. Submerged cutting characteristics of abrasive suspension jet

    International Nuclear Information System (INIS)

    Shimizu, Seiji; Peng, Guoyi; Oguma, Yasuyuki; Nishikata, Hiroki

    2015-01-01

    An abrasive suspension jet (ASJ) formed by propelling abrasive suspension through a nozzle has a greater cutting capability than the conventional abrasive water jet. However the cutting capability of submerged ASJs decreases drastically with increasing the standoff distance and the pressure around the jet. A sheathed nozzle nozzle with ventilation for ASJs has been developed as a mean of extending the effective stand-off distance and improving the cutting capabilities under submerged condition. In the present investigation, cutting tests by ASJs in air and under submerged condition are conducted with specimens of aluminum alloy. Air coated ASJs are formed by using a sheathed nozzle with ventilation. The relative cutting depth is defined as the cutting depth is arranged effectually by the cavitation number based on the cavity pressure measured at the sheath. (author)

  16. Compressed Air Production Using Vehicle Suspension

    Directory of Open Access Journals (Sweden)

    Ninad Arun Malpure

    2015-08-01

    Full Text Available Abstract Generally compressed air is produced using different types of air compressors which consumes lot of electric energy and is noisy. In this paper an innovative idea is put forth for production of compressed air using movement of vehicle suspension which normal is wasted. The conversion of the force energy into the compressed air is carried out by the mechanism which consists of the vehicle suspension system hydraulic cylinder Non-return valve air compressor and air receiver. We are collecting air in the cylinder and store this energy into the tank by simply driving the vehicle. This method is non-conventional as no fuel input is required and is least polluting.

  17. Vibration Reduction System Using Magnetic Suspension Technology

    Directory of Open Access Journals (Sweden)

    Spychała Jarosław

    2015-01-01

    Full Text Available The article presents considerations concerning the construction of vibration reduction system using magnetic suspension technology. Presents the results of simulation, numerical and experimental the bearingless electric motor, for which successfully used this type of solution. Positive results of research and testing have become the basis for the development of the concept of building this type of active vibration reduction system , at the same time acting as a support for a technical object, which is a jet engine. Bearing failures are manifested by loss or distortion of their mass, which leads to a total destruction of the roller bearing, and thus reflected in the security. The article presents the concept of building active magnetic suspension to eliminate the bearing system of classical rolling bearing and replace it with magnetic bearing.

  18. Better flocculants by radiation induced polymerization

    International Nuclear Information System (INIS)

    Laizier, J.; Gaussens, G.

    1978-01-01

    The use of radiation induced polymerization should theoritically allow to prepare better flocculants. The testings of several products prepared by such a process shows that better properties are indeed obtained: better efficiencies, lower amounts needed, better overall properties [fr

  19. Compression Behavior of High Performance Polymeric Fibers

    National Research Council Canada - National Science Library

    Kumar, Satish

    2003-01-01

    Hydrogen bonding has proven to be effective in improving the compressive strength of rigid-rod polymeric fibers without resulting in a decrease in tensile strength while covalent crosslinking results in brittle fibers...

  20. Silicon dioxide obtained by Polymeric Precursor Method

    International Nuclear Information System (INIS)

    Oliveira, C.T.; Granado, S.R.; Lopes, S.A.; Cavalheiro, A.A.

    2011-01-01

    The Polymeric Precursor Method is able for obtaining several oxide material types with high surface area even obtained in particle form. Several MO 2 oxide types such as titanium, silicon and zirconium ones can be obtained by this methodology. In this work, the synthesis of silicon oxide was monitored by thermal analysis, XRD and surface area analysis in order to demonstrate the influence of the several synthesis and calcining parameters. Surface area values as higher as 370m2/g and increasing in the micropore volume nm were obtained when the material was synthesized by using ethylene glycol as polymerizing agent. XRD analysis showed that the material is amorphous when calcinated at 600°C in despite of the time of calcining, but the material morphology is strongly influenced by the polymeric resin composition. Using Glycerol as polymerizing agent, the pore size increase and the surface area goes down with the increasing in decomposition time, when compared to ethylene glycol. (author)

  1. Thermal polymerization of Moringa oleifera oil

    International Nuclear Information System (INIS)

    Melo, Tania M.S.; Novack, Katia M.; Leandro, Cristiano

    2011-01-01

    It is increasingly clear both for society and the scientific community, that is necessary to find alternatives to reduce the use of polymeric materials because of their damage to the environment. One way to minimize the environmental problems related to the use of polymers is try to make them quickly degradable. In this study it was obtained a material with polymeric appearance derived from heating of the vegetable oil extracted from seeds of Moringa oleifera. The resulting product is an interesting alternative to obtain polymeric materials that may have biodegradable characteristics, coming from a renewable source and low cost. Moringa oil can be used since it has a high content of unsaturated fatty acids, and its main constituent oleic acid. All samples were characterized by FTIR, NMR and GPC. It was obtained a polymeric material, malleable, high viscosity, with some elasticity, low crystallinity and no unpleasant odor. (author)

  2. Deformation and flow of polymeric materials

    CERN Document Server

    Münstedt, Helmut

    2014-01-01

    This book describes the properties of single polymer molecules and polymeric materials and the methods how to characterize them. Molar masses, molar mass distributions and branching structure are discussed in detail. These properties are decisive for a deeper understanding of structure/properties relationships of polymeric materials. This book therefore describes and discusses them in detail. The mechanical behavior as a function of time and temperature is a key subject of the book. The authors present it on the basis of many original results they have obtained in their long research careers. They present the temperature dependence of mechanical properties of various polymeric materials in a wide temperature range: from cryogenic temperatures to the melt. Besides an extensive data collection on the transitions of various different polymeric materials, they also carefully present the physical explanations of the observed phenomena. Glass transition and melting temperatures are discussed, particularly, with the...

  3. Polymerization of sodium methacrylate induced by irradiation

    International Nuclear Information System (INIS)

    Galvan S, A.

    1998-01-01

    This work has two objectives, first: it is pretended to localize the lines of carbon links in its IR spectra, and second: following the polymerization of sodium methacrylate according to that it is irradiated with gamma rays. (Author)

  4. Reverse-osmosis membranes by plasma polymerization

    Science.gov (United States)

    Hollahan, J. R.; Wydeven, T.

    1972-01-01

    Thin allyl amine polymer films were developed using plasma polymerization. Resulting dry composite membranes effectively reject sodium chloride during reverse osmosis. Films are 98% sodium chloride rejective, and 46% urea rejective.

  5. Bioadhesive polymeric platforms for transmucosal drug delivery ...

    African Journals Online (AJOL)

    Bioadhesive polymeric platforms for transmucosal drug delivery systems – a review. ... administration of certain classes of drugs, especially peptides and proteins. ... characteristics of desired bioadhesive polymers, this article then proceeds to ...

  6. Transformation kinetics of mixed polymeric substrates under ...

    African Journals Online (AJOL)

    bglucosidase and a-mannosidase were abundantly secreted in the growth medium. This research is the first report on mixed polymeric substrate biodegradation under sewer condition by A. niger, and could be considered as an open window on ...

  7. Low Reynolds number suspension gravity currents.

    Science.gov (United States)

    Saha, Sandeep; Salin, Dominique; Talon, Laurent

    2013-08-01

    The extension of a gravity current in a lock-exchange problem, proceeds as square root of time in the viscous-buoyancy phase, where there is a balance between gravitational and viscous forces. In the presence of particles however, this scenario is drastically altered, because sedimentation reduces the motive gravitational force and introduces a finite distance and time at which the gravity current halts. We investigate the spreading of low Reynolds number suspension gravity currents using a novel approach based on the Lattice-Boltzmann (LB) method. The suspension is modeled as a continuous medium with a concentration-dependent viscosity. The settling of particles is simulated using a drift flux function approach that enables us to capture sudden discontinuities in particle concentration that travel as kinematic shock waves. Thereafter a numerical investigation of lock-exchange flows between pure fluids of unequal viscosity, reveals the existence of wall layers which reduce the spreading rate substantially compared to the lubrication theory prediction. In suspension gravity currents, we observe that the settling of particles leads to the formation of two additional fronts: a horizontal front near the top that descends vertically and a sediment layer at the bottom which aggrandises due to deposition of particles. Three phases are identified in the spreading process: the final corresponding to the mutual approach of the two horizontal fronts while the laterally advancing front halts indicating that the suspension current stops even before all the particles have settled. The first two regimes represent a constant and a decreasing spreading rate respectively. Finally we conduct experiments to substantiate the conclusions of our numerical and theoretical investigation.

  8. The aqueous homogeneous suspension reactor project

    International Nuclear Information System (INIS)

    1975-01-01

    The power of the KSTR reactor has been increased up to 200 kW in the fourth quarter of 1974. A description is given of the behaviour of the reactor at increased power level, safety aspects concerned with this new level, the operation of the reactor, instrumental behavior and mechanical behavior. Irradiation investigation of two types of fuels are reported and results are presented. Progress made on the conceptual design of a 250 MWe suspension reactor is described

  9. A Model of Active Roll Vehicle Suspension

    Directory of Open Access Journals (Sweden)

    I. Čech

    2010-01-01

    Full Text Available This paper describes active suspension with active roll for four-wheel vehicle (bus by means of an in-series pump actuator with doubled hydropneumatic springs. It also gives full control law with no sky-craping. Lateral stiffness and solid axle geometry in the mechanical model are not neglected. Responses to lateral input as well as responses to statistical unevennesses show considerable improvement of passengers comfort and safety when cornering.

  10. Geometrical analysis of suspension flows near jamming

    Science.gov (United States)

    Wyart, Matthieu

    2012-02-01

    The viscosity of suspensions was computed early on by Einstein and Batchelor in the dilute regime. At high density however, their rheology remains mystifying. As the packing fraction increases, steric hindrance becomes dominant and particles move under stress in a more and more coordinated way. Eventually, the viscosity diverges as the suspension jams into an amorphous solid. Such a jamming transition is reminiscent of critical points: the rheology displays scaling and a diverging length scale. Jamming bear similarities with the glass transition where steric hindrance is enhanced under cooling, and where the dynamics is also observed to become more and more collective as it slows down. In all these examples, understanding the nature of the collective dynamics and the associated rheology remains a challenge. Recent progress has been made however on a related problem, the unjamming transition where a solid made of repulsive soft particles is isotropically decompressed toward vanishing pressure. In this situation various properties of the amorphous solid, such as elasticity, transport or force propagation, display scaling with the distance to threshold. Theoretically these observations can be shown to stem from the presence of soft modes in the vibrational spectrum, a result that can be extended to thermal colloidal glasses as well. Here we focus on particles driven by shear at zero temperature. We show that if hydrodynamical interactions are neglected an analogy can be made between the rheology of such a suspension and the elasticity of simple networks, building a link between the jamming and the unjamming transition. This analogy enables us to unify in a common framework key aspects of the elasticity of amorphous solids with the rheology of dense suspensions, and to relate features of the latter to the geometry of configurations visited under flow.

  11. Torsional asymmetry in suspension bridge systems

    Czech Academy of Sciences Publication Activity Database

    Malík, Josef

    2015-01-01

    Roč. 60, č. 6 (2015), s. 677-701 ISSN 0862-7940 R&D Projects: GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : suspension bridge * Hamilton principle * vertical and torsional oscillation * uniqueness * existence Subject RIV: BA - General Mathematics Impact factor: 0.507, year: 2015 http://link.springer.com/article/10.1007%2Fs10492-015-0117-3

  12. Compounded Apixaban Suspensions for Enteral Feeding Tubes.

    Science.gov (United States)

    Caraballo, Maria L; Donmez, Seda; Nathan, Kobi; Zhao, Fang

    2017-07-01

    Objective: There is limited information on compounded apixaban formulations for administration via enteral feeding tubes. This study was designed to identify a suitable apixaban suspension formulation that is easy to prepare in a pharmacy setting, is compatible with commonly used feeding tubes, and has a beyond-use date of 7 days. Methods: Apixaban suspensions were prepared from commercially available 5-mg Eliquis tablets. Several vehicles and compounding methods were screened for ease of preparation, dosage accuracy, and tube compatibility. Two tubing types, polyurethane and polyvinyl chloride, with varying lengths and diameters, were included in the study. They were mounted on a peg board during evaluation to mimic the patient body position. A 7-day stability study of the selected formulation was also conducted. Results: Vehicles containing 40% to 60% Ora-Plus in water all exhibited satisfactory flowability through the tubes. The mortar/pestle compounding method was found to produce more accurate and consistent apixaban suspensions than the pill crusher or crushing syringe method. The selected formulation, 0.25 mg/mL apixaban in 50:50 Ora-Plus:water, was compatible with both tubing types, retaining >98% drug in posttube samples. The stability study also confirmed that this formulation was stable physically and chemically over 7 days of storage at room temperature. Conclusions: A suitable apixaban suspension formulation was identified for administration via enteral feeding tubes. The formulation consisted of 0.25 mg/mL apixaban in 50:50 Ora-Plus:water. The stability study results supported a beyond-use date of 7 days at room temperature.

  13. Spectral analysis connected with suspension bridge systems

    Czech Academy of Sciences Publication Activity Database

    Malík, Josef

    2016-01-01

    Roč. 81, č. 1 (2016), s. 42-75 ISSN 0272-4960 R&D Projects: GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : suspension bridge * vertical and torsional oscillation * eigenvalue * eigenvector * flutter Subject RIV: JM - Building Engineering Impact factor: 0.945, year: 2016 http://imamat.oxfordjournals.org/content/early/2015/09/16/imamat.hxv027.short?rss=1

  14. Real time in situ spectroscopic characterization of radiation induced cationic polymerization of glycidyl ethers

    International Nuclear Information System (INIS)

    Mascioni, Matteo; Sands, James M.; Palmese, Giuseppe R.

    2003-01-01

    Radiation curable polymeric materials suffer from relatively poor mechanical properties. Moreover, the curing behavior of such systems (i.e. the exact relationship between chemical kinetics and key processing variables) is not fully understood. In order to design improved epoxy based electron beam (EB) curable systems, and in order to develop appropriate process models, a detailed knowledge of the kinetics of epoxy cationic polymerization induced by ultraviolet (UV) or EB irradiation is required. In this work, we present our development of a technique based on real time near infrared (RTIR) spectroscopy for performing in situ kinetic analysis of radiation induced cationic polymerization of epoxy systems. To our knowledge this is the first time such data have been collected and presented for high-energy EB (10 MeV) induced polymerization. A demonstration of the technique for deterministic evaluation of degree of cure is shown using model glycidyl ether (phenyl glycidyl ether and diglycidyl ether of bisphenol A) resins and isothermal curing conditions. The impact of initiation rate on polymerizations with UV and EB for the cationic initiator is directly evident by comparative analysis. The sensitivity of the RTIR method and ability to produce quantitative data evidence of reaction mechanisms is demonstrated. The type of data presented in this work forms the basis for cure models being developed

  15. Post polymerization cure shape memory polymers

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Thomas S.; Hearon, II, Michael Keith; Bearinger, Jane P.

    2017-01-10

    This invention relates to chemical polymer compositions, methods of synthesis, and fabrication methods for devices regarding polymers capable of displaying shape memory behavior (SMPs) and which can first be polymerized to a linear or branched polymeric structure, having thermoplastic properties, subsequently processed into a device through processes typical of polymer melts, solutions, and dispersions and then crossed linked to a shape memory thermoset polymer retaining the processed shape.

  16. Nucleotide Selectivity in Abiotic RNA Polymerization Reactions

    Science.gov (United States)

    Coari, Kristin M.; Martin, Rebecca C.; Jain, Kopal; McGown, Linda B.

    2017-09-01

    In order to establish an RNA world on early Earth, the nucleotides must form polymers through chemical rather than biochemical reactions. The polymerization products must be long enough to perform catalytic functions, including self-replication, and to preserve genetic information. These functions depend not only on the length of the polymers, but also on their sequences. To date, studies of abiotic RNA polymerization generally have focused on routes to polymerization of a single nucleotide and lengths of the homopolymer products. Less work has been done the selectivity of the reaction toward incorporation of some nucleotides over others in nucleotide mixtures. Such information is an essential step toward understanding the chemical evolution of RNA. To address this question, in the present work RNA polymerization reactions were performed in the presence of montmorillonite clay catalyst. The nucleotides included the monophosphates of adenosine, cytosine, guanosine, uridine and inosine. Experiments included reactions of mixtures of an imidazole-activated nucleotide (ImpX) with one or more unactivated nucleotides (XMP), of two or more ImpX, and of XMP that were activated in situ in the polymerization reaction itself. The reaction products were analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to identify the lengths and nucleotide compositions of the polymerization products. The results show that the extent of polymerization, the degree of heteropolymerization vs. homopolymerization, and the composition of the polymeric products all vary among the different nucleotides and depend upon which nucleotides and how many different nucleotides are present in the mixture.

  17. Nucleotide Selectivity in Abiotic RNA Polymerization Reactions.

    Science.gov (United States)

    Coari, Kristin M; Martin, Rebecca C; Jain, Kopal; McGown, Linda B

    2017-09-01

    In order to establish an RNA world on early Earth, the nucleotides must form polymers through chemical rather than biochemical reactions. The polymerization products must be long enough to perform catalytic functions, including self-replication, and to preserve genetic information. These functions depend not only on the length of the polymers, but also on their sequences. To date, studies of abiotic RNA polymerization generally have focused on routes to polymerization of a single nucleotide and lengths of the homopolymer products. Less work has been done the selectivity of the reaction toward incorporation of some nucleotides over others in nucleotide mixtures. Such information is an essential step toward understanding the chemical evolution of RNA. To address this question, in the present work RNA polymerization reactions were performed in the presence of montmorillonite clay catalyst. The nucleotides included the monophosphates of adenosine, cytosine, guanosine, uridine and inosine. Experiments included reactions of mixtures of an imidazole-activated nucleotide (ImpX) with one or more unactivated nucleotides (XMP), of two or more ImpX, and of XMP that were activated in situ in the polymerization reaction itself. The reaction products were analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to identify the lengths and nucleotide compositions of the polymerization products. The results show that the extent of polymerization, the degree of heteropolymerization vs. homopolymerization, and the composition of the polymeric products all vary among the different nucleotides and depend upon which nucleotides and how many different nucleotides are present in the mixture.

  18. Volumetric polymerization shrinkage of contemporary composite resins

    Directory of Open Access Journals (Sweden)

    Halim Nagem Filho

    2007-10-01

    Full Text Available The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill Magic, Alert, and Solitaire to determine whether there are differences among these materials. The tests were conducted with precision of 0.1 mg. The volumetric shrinkage was measured by hydrostatic weighing before and after polymerization and calculated by known mathematical equations. One-way ANOVA (a or = 0.05 was used to determine statistically significant differences in volumetric shrinkage among the tested composite resins. Suprafill (1.87±0.01 and Definite (1.89±0.01 shrank significantly less than the other composite resins. SureFil (2.01±0.06, Filtek Z250 (1.99±0.03, and Fill Magic (2.02±0.02 presented intermediate levels of polymerization shrinkage. Alert and Solitaire presented the highest degree of polymerization shrinkage. Knowing the polymerization shrinkage rates of the commercially available composite resins, the dentist would be able to choose between using composite resins with lower polymerization shrinkage rates or adopting technical or operational procedures to minimize the adverse effects deriving from resin contraction during light-activation.

  19. Post polymerization cure shape memory polymers

    Science.gov (United States)

    Wilson, Thomas S; Hearon, Michael Keith; Bearinger, Jane P

    2014-11-11

    This invention relates to chemical polymer compositions, methods of synthesis, and fabrication methods for devices regarding polymers capable of displaying shape memory behavior (SMPs) and which can first be polymerized to a linear or branched polymeric structure, having thermoplastic properties, subsequently processed into a device through processes typical of polymer melts, solutions, and dispersions and then crossed linked to a shape memory thermoset polymer retaining the processed shape.

  20. Design of a suspension system and determining suspension parameters of a medium downforce small Formula type car

    Directory of Open Access Journals (Sweden)

    Biswal Sadjyot

    2017-01-01

    Full Text Available The focus of the paper is on designing a suspension system for a medium downforce small Formula type race car. The paper not only focusses on step by step design for a double wishbone type suspension but will also show the use and role of kinematics software in determining the optimized suspension of the car. The paper will also focus on the use of tire data in determining suspension parameters and the design of the double wishbone suspension. Various parameters, their design importance and the process to optimize them according to suspension design goals will be covered. The easiest and best ways to change the suspension parameters to get the best results will also be covered.